Physics and engineering.

Chair: S. Kant Vajpayee, University of Southern Mississippi

Vice-chair: Erdem Topsakal, Mississippi State University 

THURSDAY MORNING

Bost Theater

8:00 SURPRISED! SURPRISED! CT SCANS IN MANUFACTURING PLANTS

S. Kant Vajpayee, University of Southern Mississippi, Hattiesburg, MS 39406

We associate the term CT scans usually with hospitals, physicians, and the like. Recently, CT scans have begun to enter manufacturing. They are evolving to help production engineers for the same reasons they help physicians. Like all technologies, manufacturing had to wait for CT scans until these became affordable. The CT scan technology is proving extremely useful since it fits in nicely with the modern philosophy of preventing defects, rather than inspecting it at the end of the production. The defects are identified and quantified; the associated data are used for taking timely corrective actions. X-ray computed tomography (CT) is one of the several non-destructive testing tools. However, it is the only one which can measure internal features non-destructively. It complements other inspection tools such as coordinate measuring machines (CMMs) and non-contact optical scanners that are suitable for external features. CT scans helps seeing inside a part to identify porosity, blockage, cracks, inclusions, voids, and mechanical fit. CT uses X-rays to produce cross-sectional views of the part under inspection. The CT data help create a 3-dimensional volumetric image of the part using X, Y, and Z coordinates. The CT slices yield a volume stereo lithography model (STL file) of both the internal and external features. The STL file is compared with the CAD data--the output the design process. Currently, CT technology is being used for first-part inspection and in medical-implant applications to benchmark processes. But its future lies in using the CT data as negative feedback to correct for the errors of production while the part is on the production machine. CT technology can achieve measurement accuracy as high as one-thousandth of an inch.

8:15 COMPARISON OF GENETIC ALGORITHM VERSUS PARTICLE SWARM OPTIMIZATION IN THE ADAPTIVE NULLING OF PHASED ARRAY ANTENNAS

Andy Harrison*, deciBel Research, Inc., Huntsville, AL 35806

When operating a system in the presence of one or more strong interfering sources, low sidelobe levels may not be enough to ensure adequate reception of the desired signal. A method for overcoming this problem is adaptive nulling. In this method, the amplitude and phase coefficients of each element in the phased array are adjusted in such a fashion as to place a null in the antenna pattern in the direction of the interfering sources. Many adaptive nulling algorithms calculate the adaptive weighting coefficients for each antenna element by multiplying the original coefficients by the inverse of the covariance matrix. While this method is computationally fast, quantization of the phase will result in errors in null placement. Also, it is necessary to have receiver hardware at each element of the phased array as well as an elaborate calibration technique. Genetic algorithm and particle swarm techniques are global search methods that place very deep nulls in the desired directions, while maintaining the characteristics of the antenna main beam. Since the solution space is predefined by the quantized amplitude and phase coefficients of the particular antenna system, these global methods do not require continuous amplitude and phase shifts. Additionally, these methods deal with the coherent output power of the antenna array and therefore do not require receiver hardware at each element in the antenna array.

8:30 WHY WE NEED STRING THEORY FOR THE UNIVERSE?

Amin Haque, Alcorn State University, Lorman, MS 39096

The current unsolved mysteries in physics are the birth of the Universe, the beginning of time, the cause of the Universe inflation, dark matter, dark energy, and the black holes. According to Hubble's law and other evidence, the Universe was born with a Big Bang about 14.5 billion years ago. A fraction of microsecond later, it started expanding at an extremely high rate for a brief period of time. Within billion years the galaxies began to form with the aid of dark matter, which is believed to hold them together. A mysterious force, called dark energy, is believed to be responsible for the continuous expansion of the Universe at an accelerating rate. We want to go deeper to understand why things happened the way they did. Einstein's general theory of relativity describes only large objects ? the solar system, galaxies, and the Universe. Physicists discovered new building blocks of matter and laws that govern their behavior. The standard model of particle physics was developed, which is an expansion of quantum theory and describes the behavior of elementary particles very satisfactorily. Having two different theories for one Universe is not satisfactory. It should be possible to unify the standard model and general theory of relativity into one complete and comprehensive theory that should describe the behavior of atoms as well as stars. String theory promises new insights and offers hope that answers to at least some of these puzzles may be on the horizon.

8:45 SUPERSTRING THEORY AND THE UNIVERSE

Amin Haque, Alcorn State University, Lorman, MS 39096

String theory attempts to unify all four forces of the nature--gravity, electromagnetic, weak, and strong. According to string theory, all the particles of the Universe and all the force carriers are different modes of vibration of extremely tiny fibers or strings. The observed particle properties (mass, charge, spin) are determined by the strings' oscillatory patterns. Force carriers--graviton, photons, weak gauge bosons, and gluons--are yet other patters of vibration. The units of mass, quarks and electrons (leptons) that form protons and neutrons, are actually made of still more fundamental units--Strings. According to superstring theory, to describe the motion of a string we need eleven dimensions, plus antiparticles and a mirror image of particles, called superparticles. The hidden dark matter and dark energy also may shape our Universe from these dimensions. Superstring theory also predicts that for every known matter particle to have as-yet-undiscovered corresponding "super" force carrier particle and every known force carrier particle to have corresponding "super" matter particle. The superpartners (Squark, Selectron, Sneutrino etc) are thought to be more massive than their partners (quark, electron, neutrino etc). String theory can explore what happened at the instant of the big bang, and what was before the big bang. We now believe a multiverse of universes has existed since before the big bang. At this point no experiments are possible which could prove or disprove if string theory is real or just a mathematical concept.

9:00 EFFECTS OF NONPLANARITY ON SECONDARY FLOWS IN THE SMALL BRONCHIAL TUBES 

Bela Soni*, Charla Lindley, and David Thompson, Mississippi State University, Mississippi State, MS 39762

Laminar flow in the small bronchial tubes, characterized by a Reynolds number range of approximately 100 to 1000, is quite complex due to the presence of vortex-dominated secondary flows that play a critical but poorly understood role in the filtration of entrained particles from inhaled air. Contributing to the complexity of the problem is the geometry of the bronchial network, which contains nonplanar, multi-generational branching. The out-of-plane branch angles are randomly distributed in a manner that allows the bronchial network to fill the space available in the chest cavity without intersections. In this paper, we present the results of computational fluid dynamics simulations for steady-state inhalation flow in four three-generation geometries. Since the branching angles are randomly distributed in, we limit this study to only cases for which the branching occurs in the plane perpendicular to the previous branch or the plane of the previous branch. Various fluid dynamical properties are employed to describe the differences between the flows.

9:15 PARTICIPATING IN DoD RESIDENTIAL PROTON EXCANGE MEMBRANE (PEM) FUEL CELL(FC) PROJECT BY ALCORN STATE UNIVERSITY AND THE PARAMETRIC STUDY OF PEM-FC OPERATION

Sam Aceil*, Alcorn State University, Lorman, MS 39096

Distributed electric power generation is considered as a possible substitute for the current centralized power generation for certain usage. Starting 2001, the Department of Defense (DoD) funded a numbers of PEM fuel cells at various military sites with different climates. The Alcorn State University (ASU) Reserve Officers' Training Corps (ROTC) building was selected as one those sites during the 2004 Fiscal Year (FY04). The 5KW Plugpower GenSys PEM Fuel Cell arrived on campus on January of 2006 and the installation completed by March 2006 at ROTC building. The DoD contractor closely monitors the operation of the FC system remotely for one year as part of their contract with DoD. The data is also avail to ASU for their investigations. Parameters under investigation include electric and cogeneration power and efficiency, availability, unscheduled down-time, capacity factor, fuel consumption, total KWh, available KWh, electric efficiency. This paper discusses the results of the operation obtained so far.

9:30 MECHANISM OF DYNAMIC RECRYSTALLIZATION DURING THE FRICTION STIR WELD PROCESS

Lei Dong*, and Judy Schneider, Mississippi State University, Mississippi State, MS 39762

Friction Stir welding (FSW) is becoming an increasingly popular, solid state method for joining materials which are difficult to join by conventional fusion weld methods. Based on microstructural characterization of the FSW, three distinct zones can been identified: heat-affected zone (HAZ), thermo-mechanically affected zone (TMAZ), and refined zone (NZ). Many researchers attribute the formation of the ultrafine grains in the NZ to dynamic recrytallization (DRX). Although this mechanism is postulated, recovery rather than recrytallization is normally observed in alloys such aluminum with high stacking fault energy (SFE). Based on a review of the literature, there does not appear to be a consensus regarding the mechanism of grain refinement mechanism in the NZ. In our experiments, the use of metal cutting theory is being used to describe the thermo-mechanical processes the metal experiences during the FSW process. Using this analogy, a shear zone is expected to form around the weld tool. If the resulting microstructure found in machine chips can be correlated with the microstructure of the FSW in NZ, then this approach may help to quantify the thermo-mechanical conditions required for grain refinement.

9:45 Break

10:00 THE DIPOLE VORTEX

Henk Arnoldus*, Mississippi State University, Mississippi State, MS 39762

When light is observed by for instance the human eye, a camera or a photomultiplier in a laboratory, the distance between the detector and the source of the light is largely irrelevant. Light emanating from a source appears to travel in rays, e.g., it seems to propagate along straight lines from the source to the detector. This picture changes dramatically when we consider the spatial structure of the energy flow on a scale of an optical wavelength. We shall show that the light emitted by a point dipole, which is the most common source of electromagnetic radiation, emerges from the dipole in a peculiar way. The flow lines of the emitted energy form an optical vortex in the sense that the energy flow lines first swirls around the axis of the dipole before turning into an optical ray. We shall also consider the effect of such an optical vortex on the induced electrical current in a nearby interface with a conducting material. The current density, which is generated by the dipole, can have a very intricate structure, depending on the orientation of the dipole with respect to the boundary, and depending on whether it is an electric or a magnetic dipole.

10:15 SIMULATION AND PERFORMANCE EVALUATION OF BEST HOPPING SEQUENCE SELECTION PROTOCOL FOR INCREASING BATTERY LIFE OF UNMANNED AIRBONE VEHICLES

Amer Magableh*, Ibrahim Y. Abualhaol, Mustafa M. Matalgah, Atef Z. Elsherbeni, University of Mississippi, University, MS 38677

Frequency hopping (FH) is one of two basic spreading techniques used in spread spectrum communication to minimize the effectiveness of electronic warfare or jamming. The concept of FH is used in Unmanned Airborne Vehicle (UAV) transmission mainly to extend the battery life. We propose a new technique for FH, which is based on assigning multiple subchannel hops to handle the transmission. The number of subchannels and their selection are based on the required data rate and the signal-to-interference-plus-noise ratio (SINR) for each sub-channel. In our model, we assume the UAV uses adaptive modulation and coding techniques, and the transmission is carried over 16 sub-channels, each with 5 MHz bandwidth and span 80 MHz of bandwidth at the 2.4 GHz spectrum. The proposed new technique namely. Best Hopping Sequence Selection Protocol (BHSSP) is based on selecting a partial set of sub-channels based on a pre-defined minimum transmission data rate. The objective is to find a minimum number of sub-channels to be assigned to the link satisfying the minimum required data rate. Therefore, the sub-channels data rates should be determined, which are associated with the estimated SINRs. The BHSSP is implemented in simulink software package to simulate the system and evaluate its performance before going to real time implementation. The proposed simulink model for this new protocol contains a real-time estimator for the SINR of the 16 sub-channels. The BHSSP provides input to the communication system about which frequency hopping sequence to use in order to minimize power consumption and therefore increase battery life.

10:30 CIRCUIT MODEL AND FULL WAVE ANALYSIS OF A COMPACT WIDEBAND QUARDARTUE HYBRID

Adarsh Jaiswal* and Ahmed A. Kishk, University of Mississippi, University, MS 38677

A printed, compact and wideband quadrature hybrid is designed by utilizing the multi-section technique for bandwidth enhancement and equivalent transmission line technique for size reduction. The compact quadrature hybrid has a size reduction of 50% as compared with the conventional quadrature hybrid. The compact hybrid achieves over 50% bandwidth at a centre frequency of 2 GHz. A circuit model and a full wave model are introduced and analyzed using Agilent Advanced Design System. Excellent agreement between the simulated and the fabricated hybrid is achieved which indicates that the circuit and full wave models are indeed good representation of the fabricated compact wideband quadrature hybrid.

10:45 LASER-INDUCED FLUORESCENCE SPECTROSCOPY INVESTIGATION OF URANYL COMPOUNDS

Guangjun Wang*, Yi Su, and David Monts*, Mississippi State University, Mississippi State, MS 39762

Uranyl (U[O.sub.2]) compounds exhibit a characteristic fluorescence spectrum in the 450-600 nm spectral region when excited by wavelengths in the ultraviolet or in the short-wavelength portion of the visible spectrum. We report a parametric study of the effects of excitation wavelength (including 532 nm, 409 nm, 355 nm, and 266 nm), excitation laser power, and concentration on the laser-induced fluorescence (LIF) spectra of simple uranium compounds. The uranium compounds investigated include uranium dioxide, triuranium octaoxide, uranyl acetate, uranyl formate, uranyl nitrate, uranyl sulfate, and uranyl phosphate.

11:00 A PARTITIONED LOOP ANTENNA WITH OMNIDIRECTIONAL PERFORMANCE AT 5.8 GHZ

Roger Hasse*, Darko Kajfez, Veysel Demir, and Atef Z. Elsherbeni, University of Mississippi, University, MS 38677

When the dimensions of a loop antenna are on the order of the operational wavelength or larger, the current flowing in the loop exhibits phase changes that degrade the radiation efficiency. In this study a center-driven square loop antenna is designed at 5.8 GHz by partitioning the loop geometry with capacitive elements at strategic locations in order to maintain a nearly constant phase of current flow and enhance the radiation performance. A thin-wire loop antenna of radius 0.5 mm and side s = & lambda/4 mm is simulated using the AWAS software package, with an input impedance close to 50 & Omega and return loss of -35 dB at 5.8 GHz. Five capacitive elements ranging from 0.04-0.07 p Fare used to achieve optimal current flow. The calculated radiation pattern in the plane of the loop is close to omnidirectional with directive gain of 1.5 dB. The simulated performance of the wire antenna and the equivalent printed structure is validated using a finite difference time domain (FDTD) package. Introduction of capacitive elements is investigated by using proximity coupling of conductor strips, and by alternating top- and bottom-layer conductors whose regions of overlap function as physical capacitors due to the intermediate dielectric medium. Such a partitioned antenna can serve as an alternative to the more complicated designs for producing omnidirectional pattern due to its simplicity of fabrication.

11:15 MODAL ANALYSIS OF METAMATERIAL SLAB WAVEGUIDES

Hafeez Olanigan* and Alexander B Yakovlev, University of Mississippi, University, MS 38677

Metamaterial slab waveguides obtained by homogenization of realistic metamaterial structures composed of periodic lattices of split-ring resonators are investigated in this work. These waveguides allow backward waves to propagate, such that phase and group velocities have opposite directions. Metamaterial slab waveguides represent isotropic magneto-dielectric slabs, wherein frequency-dependent permittivity and permeability are both negative within certain frequency band. In this work, we characterize the behavior of transverse electric (TE) and transverse magnetic (TM) electromagnetic surface waves on a metamaterial grounded slab and compare to the modal behavior of TE and TM surface waves on conventional dielectric slabs. In particular, it is shown that the modal spectrum consists of proper (bound) and improper (with fields growing in the cover region), propagating and evanescent, and real and complex modes. It is important to note that leaky modes do not exist on double-negative metamaterial slabs (they are classified as complex propagating surface wave modes). Dispersion behavior and field distribution of TE and TM surface waves are studied for metamaterial slabs of different thickness and compared to those for conventional dielectric slab waveguides.

11:30 POWER GENERATION WITH A LOW TEMPERATURE DIFFERENCE STIRLING ENGINE

Christopher Peters*, and Richard Raspet, University of Mississippi, University, MS 38677

Classroom demonstration Stirling engines will drive a rotating disc with temperature differences as low as the difference between body temperature and room temperature. This led us to wonder if the demonstration engine could be used to produce power from waste heat, and if so, what efficiency could be achieved. In this study, we converted the mechanical energy produced from a low AT Stirling engine into electrical energy using magnets mounted on the rotating disc and an induction coil. The study included the application of thermodynamic principles such as convection and conduction to evaluate the thermodynamic efficiency. We will present data on the electrical output of this engine and compare the efficiency to thermoelectric devices that convert waste heat to electricity directly.

11:45 THE STATISTICS OF ACOUSTIC BACKSCATTER FROM THE SEAFLOOR

Jerald Caruthers, University of Southern Mississippi, Hattiesburg, MS 39406

Acoustic backscatter from the seafloor is a random process the statistical details of which provide information about the composition and geomorphology of the bottom interface and volume inhomogeneities below. Frequencies above about 50 kHz reveal information mostly about the seafloor at or just below its surface, while lower frequencies provide information from greater depths. Often with such data we seek to classify the seafloor into regimes such as sedimentary materials, e.g., sand or soft sediments, or forms such as sand ripples, shell-bit inclusions, subbottom layering, or other inhomogeneities. Generally, within some area of interest, the nature of the bottom changes from one region to another. So we are interested in developing algorithms for the most effective and expeditious means of "seafloor classification" and "change detection" based on data we collect at various frequencies. We will discuss the statistical character of seafloor backscatter data we have collected with a specially modified side-scan sonar operating at 150 and 300 kHz for the analyses of seafloor surface features and the design and planning for a new Multibeam SubBottom Profiler operating at 12 kHz that USM is presently building

THURSDAY AFTERNOON

Bost Theater

1:15 DESIGN OF SINGLE AND DUAL BAND CIRCULARLY POLARIZED MICROSTRIP PATCH ANTENNAS

Tejaswi Makineni*, Fan Yang, and Atef Z. Elsherbeni, The University of Mississippi, University, MS 38677

In this paper, different feeding mechanisms are considered to design circularly polarized microstrip patch antennas. The first is a single feed circularly polarized (CP) microstrip patch antenna. This design is achieved by embedding two tuning stubs on opposite sides of the patch antenna and placing a coaxial feed at the diagonal of the square patch. The second is a dual microstrip line feeding structure to create circularly polarized microstrip antenna. Since high impedance microstrip lines are difficult to fabricate, the antenna is feed through vias that are connected to 100 Ohm microstrip lines on the other side of the ground plane. The radiation performance of these two designs is compared with each other. Based on the above single band CP designs, a dual band CP microstrip patch antenna will be developed. Simulation and experimental study for sample designs are to be provided during the presentation.

1:30 PERMITTIVITY MEASUREMENT IN CUSTOM-SIZED WAVEGUIDE FIXTURES

Ravi K. Challa*, Veysel Demir, Darko Kajfez, Joseph R. Gladden, and Atef Z. Elsherbeni, University of Mississippi, University, MS 38677

The complex permittivity measurement is typically performed by utilizing the standard-sized waveguides, which come with associated coaxial to waveguide transitions, matched loads and possibly other specialized attachments like a moving short. We would like to present a novel procedure for extraction of complex permittivity using custom-sized square waveguide, without the need of a matched load. We propose to measure the two-port S-parameters using the TRL calibration method. With the measured S-parameters, the real part of the permittivity will be extracted from all four S-parameters using both forward and inverse techniques. The imaginary part is obtained by recomputing the value of the reflection coefficient for the short-circuited sample, and then determining the value of the unloaded Q factor by data fitting (software QZERO). The loss tangent is then equal to the inverse of the Q factor. It was found that, by using this procedure we can measure the imaginary part of permittivity accurately.

1:45 WIDEBAND DESIGNS OF ARTIFICIAL MAGNETIC CONDUCTORS USING FREQUENCY SELECTIVE SURFACES FOR LOW PROFILE ANTENNA APPLICATIONS

Gopinath Gampala* and Alexander B Yakovlev, University of Mississippi, University, MS 38677

Artificial Magnetic Conductor (AMC) ground planes have an in phase reflection property (AMC ground planes reflects the incident wave with a zero degree phase shift) applied to the design of low profile antennas. AMC is realized using periodic arrays of conducting elements called Frequency Selective Surface (FSS). In this work, new designs of wideband AMC ground planes realized by FSS structures printed on a metal backed grounded dielectric slab are presented. The bandwidth is defined between the frequencies for which the phase of the reflection coefficient at the surface of AMC ground plane lies between -90[degrees] to +90[degrees] for a plane wave of normal incidence. Three new designs of FSS structures are proposed. A nested L-loop structure, a new cross structure with unconnected arms and a near fractal structure combined with the new cross are proposed as the wideband elements for the design of AMC ground planes. Apart from the design of the periodic unit cell of the FSS structure, the bandwidth of the AMC ground planes depends on the thickness and the permittivity of the dielectric substrate. The bandwidth increases with the thickness of the substrate while it decreases for high dielectric permittivity. The proposed designs yield bandwidths of 40% to 60% for an electrical thickness of 0.1[lambda] to 0.14[lambda].

2:00 STUDY OF ARRAY CHARACTERISTICS OF A 2D PHASED ARRAY ANTENNA USING DIGITAL PHASE SHIFTERS

Suresh Kumar Yada* and Ahmed A. Kishk, University of Mississippi, University, MS 38677

Study of array factor of a two Dimensional (2D) array with rectangular lattice using different digital phase shifters is considered. Now-a-days digital phase shifters are widely used in phased array antennas as they are more immune to noise. Digital phase shifters provide discrete set of phase states depending on the number of bits used. The present work studies the effect of using specific digital phase shifters with certain number of bits on planar arrays. A study case of a planar array of a 32 by 32 element is considered with half wavelength element spacing. The numbers of bits considered are 1bit, 2 bit, 3bit, 4bit and 5bit. These results are compared to an analogue phase shifter. The array factor mainly depends on the element spacing and number of bits used along with other factors. The effect of element spacing is also considered. The factors like scan angle deviation, maximum side lobe level and directivity loss are calculated. A variation of array factors against frequency for phase shifters with different number of bits is presented. The types of phase shifters considered are true time delay lines, switched line phase shifters and constant-phase phase shifters. Different array geometries in 2D with different lattices and different number of elements are considered.

2:15 COMPETITIVE GROWTH PROCESSES AND ITS APPLICATIONS

Poonam Verma (1*) Mark A. Novotny (1), and Alice Kolokowska (2), (1) Mississippi State University, Mississippi State, MS 39762 and (2) Prudue University, Hammond, IN 46323

Our study is motivated by both applications to nonequilibrium materials growth and to algorithms for simulations on thousands of processors. We investigate some different growth processes and their corresponding universality classes and exponents. In particular, we simulate competitive two-component growth on a one dimensional substrate of L sites, which mixes Random Deposition (RD) which is uncorrelated in nature with a correlated growth process Ballistic Deposition (BD) which occurs with probability p. We find that the only effects of RD are that it stretches the time evolution of the surface roughness, but leaves the KPZ correlations intact. We identify that as p -->0 the initial phase becomes infinitely long as this is the limit of RD growth.

2:30 COMPACT ARTIFICIAL MAGNETIC CONDUCTOR DESIGN USING SPIRAL GEOMETRIES

Yanghyo Kim*, Fan Yang, and Atef. Z. Elsherbeni, University of Mississippi, University, MS, 38677

When plane waves illuminate on an electromagnetic band-gap (EBG) structure, the reflection phase continuously changes from 180[degrees] to -180[degrees]. Especially in a certain frequency where the reflection phase is 0[degrees], the surface shows the same property as a perfect magnetic conductor (PMC). The PMC material does not exist in nature, but an artificial magnetic conductor (AMC) can be realized by properly designing the EBG structure. The objective of this research is to design compact AMC structures for wireless communication and RFID applications. Spiral geometry is investigated because it can increase the equivalent inductance, resulting in a lower resonant frequency. Single and double spiral structures are first introduced and examined by the finite difference time domain (FDTD) algorithm developed by the authors. It is observed that the reflection magnitude exhibits a large cross polarization over a high frequency range, 11 GHz to 30 GHz, which should be avoided in an AMC design. To eliminate the cross polarization, a four arm spiral element has been designed, which cancels the cross polarized fields in an opposite direction. The resonant frequency is 43.2 % lower than a traditional EBG structure. The proposed spiral AMC material is a good candidate for various antenna applications.

2:45 Break

3:00 TAGUCHI'S METHOD FOR OPTIMIZING MICROWAVE FILTERS

Wei-Chung Weng*, Fan Yang, and Atef Z. Elsherbeni, University of Mississippi, University, MS 38677

A new global optimization technique based on Taguchi's method is presented for microstrip filters designs. Taguchi's method effectively reduces the number of steps required in an optimization process due to the implementation of the orthogonal array thus a fast convergence speed can be obtained, which demonstrates a great potential for being a leading candidate for electromagnetic optimization tools. Microwave filters are widely used in telecommunication equipments. Filters suppress the noises coming from environment, prevent spurious signals interfering with other systems, and allow wanted signals to pass through within a specific frequency band. Although filters built with lumped elements can realize the desired frequency response, it is difficult to control the lumped elements' properties in the microwave band. Therefore passive planar printed types of filters are usually used for microwave applications. These planar filters are composed of several stubs of microstrip lines, and need to be accurately modeled due to the high frequency effects such as dispersion and dielectric/conduct loss. Therefore, an optimization technique and a full wave EM simulator are necessary tools for an optimum design of such filters. In this study, a full wave commercial simulator, IE3D along with our external Taguchi's based optimizer are used to optimize a microstrip band stop filter and a microstrip band pass filter. The desired frequency responses of the designed filters are successfully achieved with less number of iterations relative to other recently used optimizers for such applications. These application examples show the validity and efficiency of the proposed Taguchi's method for electromagnetic applications.

3:15 DETERMINATION OF WALKING HUMAN BACK FREQUENCY USING BAYESIAN PARAMETER ESTIAMTION

Asif Mehmood (1*), Paul M. Goggans (1), James M. Sabatier (2), and Alexander E. Ekimov (2), (1) University of Mississippi, University, MS 38677 and (2) National Center for Physical Acoustics, University, MS 38677

To distinguish a walking human from other moving or stationary objects in near real-time is of great interset in military as well as civilian applications. We intend to solve this problem using Bayesian parameter estimation and data obtained from an ultrasonic Doppler vibrometer (UDV). Here we describe our initial experimental and analyticalwork to develop an automated non-invasive model-based approach for recognizing people based on their measured velocity signal while walking. Our experimental set up uses an ultrasonic Doppler vibrometer as a non-contact means for obtaining data related to the velocity of the moving body components. The main advantages of using an ultrasonic vibrational measurement system is high resolution, low cost, and ease of installation. In the UDV an ultrasonic transducer directs a 50 kHz acoustic wave to the moving body surface. The returned acoustic signal, frequency modulated by the velocity of the back vibration of walking human, is received by a co-located transducer whose output is sampled to produce the output data time series. Our experiment is laboratory based and intended to determine basic capabilities. The presence of a characteristic and approximately sinusoidal back motion component in the observed velocity of a walking human is used as a basis for distinguishing a walking human from other moving objects. In this paper we present parameters estimation results for the walking human model and discuss our simulated and experimental results.

3:30 RADIATING CHARACTERISTICS OF DIPOLE ANTENNAS IN THE PRESENCE OF OBSTACLES USING THE ITERATIVE MULTRI-REGION TECHNIQUE

Mohamed Al Sharkawy*, Veysel Demir, and Atef Z. Elsherbeni, University of Mississippi, University, MS, 38677

This work presents an efficient algorithm to the solution of large scale electromagnetic radiation problems from dipole antennas and other local sources. The advantage of using the iterative multi-region technique in conjunction with some proposed enhancement procedures, involving the use of the incomplete LU preconditioning and the multiprocessors, is presented to provide a robust solution to selected antenna applications. As a starting point for further applications, the solution to the problem of a dipole antenna radiating in the presence of obstacles is investigated. Furthermore, the solution of a linear antenna arrays is evaluated with the least memory consumption and CPU time. This work is considered as a bench mark for providing a robust technique used in solving real life, large scale open boundary electromagnetic problems within significant time and memory savings.

3:45 SCATTERING OF OBLIQUELY INCIDENT PLANE WAVE FROM AN ARRAY OF CIRCULAR DIELECTRIC CYLINDERS

Bassem Henin*, Atef Z. Elsherbeni, and Mohamed Al Sharkawy, University of Mississippi, University, MS 38677

A rigorous semi-analytical solution is presented for electromagnetic scattering from an array of circular cylinders of arbitrary radii and positions due to an obliquely incident plane wave. The cylinders are illuminated by either [TM.sub.z] or [TE.sub.z]. incident plane wave. The analysis begins by representing each field component by an infinite series of cylindrical harmonic functions with unknown coefficients. Then equations based on the boundary conditions applied on the surface of each cylinder are used to deduce the values of the unknown coefficients. Two different methods are presented to check the validity of this technique. First, the principle of equal volume model is used to represent one cylinder by an array of circular cylinders and sample numerical results are given to compare the known echo width of the scattered field from one cylinder to that of an array of circular cylinders. Second, the near field is calculated to prove the validity of the boundary conditions on the surface of each cylinder. The results in both cases show excellent agreement between the calculated field and the known results from pervious work for special cases. The presented scattering technique can be extended for other types of cylinders.

4:00 THE QWEAK EXPERIMENT AND SEARCH FOR PHYSICS BEYOND THE STANDARD MODEL

Dipangkar Dutta, Mississippi State University, Mississippi State, MS 39762

Three of the four fundamental forces in nature (weak, strong and electromagnetic) have been combined (unified) into one mathematically consistent quantum field theory known as the Standard Model (SM). The SM predicts or is consistent with all known aspects of the elementary particles and their interactions over an impressive range of probes and scales. The Medium Energy Physics group at MSU is involved in several experiments that aims to challenge the predictions of the SM and look for physics beyond the SM. One of these experiments (The Q Weak experiment) proposed for Jefferson Lab in Newport News, VA utilizes parity violating electron scattering from the proton to perform a precision measurement of the weak charge of the proton. This experiment will test the SM prediction at the 10 & sigma level. Any deviation from the SM prediction would be a signal of "New physics", whereas agreement would place new and significant constraints on possible SM extensions. I will describe the Q Weak experiment and talk about the diamond micro-strip detector which will be built at MSU for this experiment.

4:15 SPECTROSCOPIC METHODS FOR IDENTIFYING BACTERIA CELLS

Vidhu Tiwari*, Fang Y. Yueh, Lakshmi Pulakat, and Jagdish P. Singh, Mississippi State University, Mississippi State, MS 39762

The spectroscopic methods were used for studying Azotobacter vinelandii--a genus of free-living diazotrophic soil bacteria. These methods include Raman and Laser Induced Fluorescence (LIF) spectroscopy. Azotobacter has generated a great deal of interest owing to their unique mode of metabolism. It is a large, obligately aerobic soil bacterium, which has one of the highest respiratory rates known among living organisms and is able to grow on a wide variety of carbohydrates, alcohols and organic acids. The Raman Scattering of Azotobacter, incubated with gold nanoparticles, was examined with 532-nm and 785-nm as an excitation laser wavelength. The basic instrumentation for characterizing the bacteria by Raman spectroscopy employed laser and miniaturized fiber optic Raman Probe. The surface enhancement effects allowed the observation of Raman spectra of such bacterial cells, and were excited in the visible/NIR region of wavelength at low incident power for minimum sample degradation. LIF spectra of Azotobacter were collected with a 410-nm diode laser as an excitation source, and a reflection probe to deliver laser beam on the sample and collect the LIF signal from the sample. Spectral contrast observed in bacteria from nitrogen fixing and non-nitrogen fixing condition was analyzed for distinguishing the bacteria cells from their respective host media.

6:00 Poster Session

Location: Bost Auditorium North

Posters may be set up between 4:00p and 4:30p

INVESTIGATION OF RFID SYSTEM PERFORMANCE IN MULTIPLE-TAG ENVIRONMENTS

Atef Z. Elsherbeni, Fan Yang, Ahmed A. Kishk, and Chasidy West*, University of Mississippi, University, MS 38677

Many corporations are working to implement radio frequency identification (RFID) systems in order to improve the tracking of inventory, reduce items that are out-of-stock, and decrease shipment delays. There are different methods of implanting RFID tags. Some are adhesive and others are woven into fabric. The effective detection range of RFID tags is affected by the system setup as well as the interaction between the RFID tags. The objective of this research is to investigate the RFID system performance under different setups and multiple tags environment. The RFID system includes a reader unit, transmitter and receiver antennas, and RFID tags. In the first setup, two transceivers and two receiver antennas were placed on opposite sides of testing room at a distance of eleven feet. Each RFID tag has its own hexadecimal identification number and was placed on a cardboard medium. Two packaging tests were performed: a single box and a multiple box scan. For the multiple-box test, subject testing includes an outer "Relay" box that contains four smaller boxes labeled A-D. Each box was assigned six tags, one for each side. The IDs of the tags were scanned and analyzed to identify the successful reading zones and reveal the interaction effect between the tags. In the second system setup, only one transmitter antenna and one receiver antenna are implemented. The "Relay" box was then elevated above the ground to identify the effective reading zones of this simplified RFID setup. This research work provides a useful reference for future RFID applications.

DYNAMIC FOCUSING OF AWARENESS IN ADAPTIVE FUZZY CONTROL SYSTEMS

Ognjen Kuljaca, Alcorn State University, Lorman, MS 39096

Adaptive fuzzy logic (FL) control architecture is described in the paper. A detailed stability proof is given using Lyapunov-like stability criteria. It is shown that the fuzzy logic control system is focusing on a different region of the state-space depending on these varying factors. The proposed FL control algorithm does not require any assumptions on the initial parameters of FL controller for the system to be stable. The performance of the FL controller is studied in detail using simulation studies. Effects of changes in initial FL parameters, plant nonlinearity, and different reference trajectories on the final FL membership functions (MF) were investigated with the intention of drawing conclusions on how the learned MFs adapt to changing environments. It was observed that input layer MFs are changing in such a way that the whole state space in which plant states are contained is covered by MFs, but also that MFs are trying to put more weight on approximating plant states at their steady trajectories after the transient is finished if the excitation is persistently excited (PE). Simulations were also performed for the step reference input. It was noted that in the case of step reference although the fuzzy controller kept the system stable, the learning was very slow. Also, the final trajectories (only a point in this case), were just barely covered by the final MFs. The conclusion was that no meaningful learning process occurred due to lack of information in step reference signal.

SEARCH FOR WOBBLING AND TRIAXIAL STRONGLY DEFORMED(TSD) STRUCTURES IN [.sup.171.Hf] AND [.sup.172.Hf]

Yanci Zhang (1*), W.C. Ma (1), D.G. Roux (1), J.A. Winger (1), R. Yadav (1), M.P. Carpenter (2), R.V.F. Janssens (2), T.L. Khoo (2), and G.B. Hagemann (3), (1) Mississippi State University, Mississippi State, MS 39762, (2) Argonne National Laboratory, Argonne, IL 60439 and (3) Neils Bohr Institute, Copenhagen, Denmark

Wobbling mode, characterized by a sequence of rotational bands with increasing number of wobbling quanta, is a low-lying collective excitation mode uniquely related to the excitation of nuclei with triaxial deformation. Theoretical calculations predicted potential energy minima with large quadrupole deformation ([member of][e.sub.2] ~ 0.4) and substantial triaxiality ([gamma]? ~ [+ or -]20[degrees]) for nuclei near Z ~ 72 and N ~ 94. In the past several years wobbling bands have been established in 161,163,165,167Lu. A number of strongly deformed (SD) bands were also observed in neighboring nuclei 168,170,173,174,175Hf. However, the wobbling mode has not been observed in any Hf nuclei. We performed an experiment searching for wobbling mode and TSD structure in 171,172Hf at Argonne National Laboratory with Gammasphere detector array. Totally 2.1 x 109 events with multiplicity [greater than or equal to]= 3 were collected. Data was sorted into database, and further analyzed using 3-dimensional cube and 4-dimensional hypercube. Five candidates of SD bands in 172Hf and two in 171Hf were identified. Detailed results will be presented.

MULTISCALE ANALYSIS OF A MAGNESIUM CORVETTE ENGINE CRADLE

David Oglesby* and Mark Horstemeyer, Mississippi State University, Mississippi State, MS 39762

A multiscale analysis was performed to develop a monotonic microstructure-mechanical property model originally developed for a cast A356-T6 aluminum to include several types of microstructural inclusions found in popular magnesium alloys used in the automotive sector. These microstructure property material models can be used for finite element analyses in which the deformation history, temperature dependence, and strain rate dependence vary. Internal state variables are used in the monotonic material model to reflect void/crack nucleation, void growth and void coalescence from the casting microstructural features such as casting porosity, shrinkage, and intermetallics. In order to determine the pertinent effects of the microstructural features, several different length scale analyses were performed. Once the pertinent effects of the microstructural features were determined and included in the microstructural mechanical property model, load-to-failure analyses were performed on an AE44 magnesium Corvette engine cradle and a failure location was predicted. Monotonic, load-to-failure experiments were then performed on several cradles and the predictive capabilities of the model were verified through the accurate prediction of the failure location.

DESIGN AND FABRICATION OF A MICROSTRIP TRL CALIBRATION KIT FOR MEASUREMENT OF RF COMPONENTS

Dalia Elsherbeni*, Lisa Jordan, W. Elliott Hutchcraft, Richard K. Gordon, Darko Kajfez, University of Mississippi, University MS, 38677

In this paper, rather than the traditional short-open-load-thru (SOLT) method, a newer calibration technique called the thru-reflect-line (TRL) is studied for use in testing packaged transistors and passive surface mount components that are typically used on microstrip. TRL is a two-port calibration procedure that uses at least three standards to define the calibrated reference plane. For non-coaxial measurements it is difficult to fabricate and characterize standards such as an open circuit or a short circuit. In addition, the device under test must be physically connected to the network analyzer by some kind of transition. As a solution, we propose the development of a TRL calibration kit in which only microstrip TRL standards are used for S-parameter characterization of non-coaxial devices. Microstrip TRL standards for the thru, reflect, and line are designed, fabricated and tested for a frequency range from 200 MHz--12 GHz. A split fixture design is built which contains microstrip to coaxial transitions to aid in measuring these devices. With this microstrip TRL calibration kit, accurate and repeatable calibrations over a broad frequency range will be verified and measurement results of several components such as transistors, inductors, capacitors, and other surface mount components will be verified.

DESIGN AND MEASUREMENT OF MICROWAVE CIRCUITS FOR A 2.45 GHZ RECEIVER

Maxwell Woolsey, John Ashmore*, Joshua Cassity*, Lorenzo Bennett, and W. Elliott Hutchcraft, University of Mississippi, University, MS 38677

Passive and active microwave receiver components were designed and measured. Microstrip technology was used at a design frequency of 2.45 GHz, which is commonly used by such technologies as wireless LAN and Bluetooth. The development of the devices, including power dividers/combiners, a directional coupler, amplifiers, and phase shifters, was examined in detail. The design phase began with initial hand calculations which were then modeled using Advanced Design System (ADS), a microwave circuit simulator. Parameter optimization was employed to fine tune the elements within the schematic analysis. Layouts were then generated from the schematic diagrams, and the device layouts were examined using full wave analysis of the ADS Momentum package. Further device tuning was often required due to the Momentum solution taking into account electromagnetic phenomena not modeled in the schematic analysis. The amplifier stages required a hybrid analysis technique, since the transistor was modeled using imported measured data. The technique involved interfacing elements in the ADS schematic utility with the microstrip circuit layout modeled in ADS Momentum in order to provide a more accurate simulation than the schematic analysis alone. When the device simulations produced acceptable results, the layouts were milled onto substrates. The devices were then measured using a network analyzer to ensure that the simulations accurately modeled the actual devices.

THE USE OF GRAPHICS PROCESSING UNITS TO ACCELERATE LINEAR ALGEBRA OPERATIONS FOR ELECTROMGNETICS SIMULATION

Maxwell Woolsey*, W. Elliott Hutchcraft, and Richard K. Gordon, University of Mississippi, University, MS 38677

The use of graphics hardware for general purpose computation has recently gained interest due to the high processing speed and inherent data parallelization of current generation graphics processing units (GPU\'s). The difficulty of realizing GPU accelerated scientific programs is abstracting the graphics processes into a collection of liner algebra routines, providing a library of parallelized functions that could speed up matrix operations such as those used in electromagnetics simulation. Early attempts at general purpose GPU computations required extensive knowledge of the graphics processes and hardware assembly language. Higher level languages from nVidia, OpenGL, and Microsoft allow programmers to write graphics programs--shaders--without focusing on assembly language. General purpose computation, however, would still involve setting up 3D environments, passing data to the GPU as texture maps, loading the shader into the GPU, and rendering the 3D scene into a buffer to run the computation--iterating as necessary. Computation on graphics hardware has been abstracted further in two experimental languages: BrookGPU from Stanford, and Accelerator from Microsoft Research. These libraries attempt, with limited success, to provide completely abstracted GPU access. Both libraries were employed to solve electromagnetics problems using the finite element method. The resulting performance levels depended greatly on the computational size, demonstrating a huge data transfer bottleneck that could only be offset with the parallel-computation of large data sets.

PERMITTIVITY AND LOSS TANGENT EXTRACTION OF COMPOSITE MATERIALS USING OPTIMIZATION TECHNIQUES

Lorenzo Bennett*, W. Elliott Hutchcraft, Richard K. Gordon, Ellen Lackey, James G. Vaughn, and Reid Averill, University of Mississippi, University, MS 38677

There are many methods for reconstructing the electric properties of materials from the scattering parameters such as the Nicholas-Ross-Weir (NRW) or Stuchly-Matuszewsky equations. It is shown that optimizing the permittivity in Advanced Design System (ADS) is also a viable option for obtaining the permittivity or loss tangent of a certain type of material. Different types of composite materials were measured in this experiment. It was assumed that the materials did not have any magnetic properties. The composite materials were placed in a rectangular waveguide(X-Band), and the S-parameters were measured in the 7 to 13 GHz range. ADS was then used to reconstruct the permittivity and loss tangent of the material from the measured data using several types of optimization techniques, such as the genetic, random, and gradient algorithms. In the results it was shown that the modeled S-parameters in ADS did converge to the measured S-parameters resulting in a unique permittivity. The permittivity results from ADS were compared to results using the NRW equations to show agreement. From the results, it is shown that this method can be a viable approach to use when measuring the electromagnetic properties of a material, and is comparable to other extraction methods.

DESIGN, FABRICATION AND TESTING OF AN RF POWER AMPLIFIER 

Lisa Jordan*, Dalia Elsherbeni, W. Elliott Hutchcraft, Darko Kajfez, Richard K. Gordon, University of Mississippi, University, MS, 38677

An RF amplifier using a Silicon Carbide (SiC) transistor was designed for power gain. The SiC transistor can support a high power density and has high thermal conductivity, making it a good choice for a power amplifier. It is a small device with large power output capability. Agilent's Advanced Design System (ADS) was used for the majority of the simulations. This particular amplifier is optimized in the range of 1.9-2.6 GHz, as this is the optimal performance range of the transistor used. The transistor used in the design is a CREE device, CRF-24010, a 10 Watt RF power Metal-Semiconductor Field-Effect Transistor (MESFET). The design of the amplifier includes a stabilization network, matching networks at the input and output, and a DC biasing network. The stabilization network ensures that the transistor will not oscillate at any frequency under any passive load or source termination. Once the transistor was stabilized, matching networks were incorporated at the input and the output of the transistor. These networks minimized the reflection and therefore optimized the gain of the system. Lastly the DC biasing network was designed to hold the desired Q-point constant while not interrupting the RF signal path. Once the design was complete, it was fabricated and tested. Measured results were encouraging with slightly less gain than the simulated results.

CAN FLOW CONTROL DEVICES SIGNIFICANTLY REDUCE DRAG?

Sumontro Lal Sinha, Sinhatech, Oxford, MS 38655

This project's aim is to determine if aerodynamic drag of non-streamlined vans and trucks could be significantly reduced by sticking tape-like devices on them. These devices only marginally modify the flow next to the surface which they are mounted. They reduce skin-friction drag on streamlined objects, especially when the tape incorporates a flexible skin to interact with and attenuate boundary-layer turbulence. It was hypothesized that such a "Deturbulator tape" could attenuate turbulent mixing in the large separated wakes of vans and trucks. The Deturbulator transforms the wakes into stagnant air masses attached to the vehicles, providing a virtual streamlining extension. This streamlining reduces drag and improves highway fuel economy. Wind tunnel tests demonstrated 80% and 25% drag reductions on a van and truck with a 36% r eduction in wake velocity fluctuations when the Deturbulator tapes were stuck at the right places on the model. Repeated measurements of highway mileage of a minivan and truck also showed 19% and 15% improvement respectively, when treated with deturbulator tape. Traditional methods for reducing vehicle drag rely on minimizing the size of the wake through promotion of turbulent mixing requiring major redesign to obtain a 5% increase in gas mileage. The present project can help reduce an estimated consumption of $33 billion in gasoline and diesel fuel costs per year, and a corresponding reduction in the emission of pollutants and carbon dioxide 225 million vehicles are treated with deturbulator tape.

THE ROLE OF MACROMOLECULES AND FIBRILS IN TENDON MECHANICS

Deborah Davis* and Lakiesha Williams, Mississippi State University, Mississippi State, MS 39762

This study examined various manuscripts investigating the contributions of macromolecules and fibrils to tendon mechanics with a goal of clarifying their roles in the tendon's overall behavior. Literature has shown the important roles that macromolecules and fibrils serve in assisting the tendon's structural integrity and function. One major role of collagen fibrils is providing stiffness and tensile strength to the tendon (Robinson et al., 2004). Redaelli et al. (2003) showed that as fibril length and diameter increase, elastic modulus, stiffness, and ultimate tensile strength increase. Redaelli et al. also observed that the macromolecules, glycosaminoglycan (GAGs), serve as bridges between contiguous fibrils, connecting adjacent fibrils. They concluded increasing fibril length increases interacting links and thus increases tendon mechanical properties. Robinson et al., 2004 indicated that the macromolecules, proteoglycans (PGs) and GAGs, transmit interfibrillar forces. Scott et al. (1981) examined the connections between collagen fibrils and PGs, showing that the connections provided fibril stabilization and organization (Kadler et al., 1996). A coupling of functions has been shown to occur between macromolecules and fibrils. This coupling has been demonstrated through microscopy and computational analysis, but not mechanically. This review will justify the need of mechanical studies that couple the roles of both macromolecules and fibrils. The future objective of this study is to determine the mechanical properties of both tendon fibrils and macromolecules and their overall impact on the mechanics of the tendon.

FRIDAY MORNING

Bost Theater

8:00 QUANTITATIVE DESCRIPTION AND PERFORMANCE ANALYSIS OF A RECTANGULAR LOOP NANOWIRE ANTENNA

Tanya Aranchuk* and Mustafa M. Matalgah, University of Mississippi, University, MS 38677

Recent advances in engineering made it possible to synthesize nanotubes with length comparable to the wavelength of microwaves (~ 1 cm). The possible use of these nanotubes as antennas has received wide attention among researchers, with applications in the areas of biochemistry, communications, engineering and many others. Attempts have been made to quantitatively analyze the performance of nanotube antennas. Thin-wire antenna geometry has been considered in the literature for this purpose. In this paper, we consider the performance analysis of a rectangular loop nanowire antenna. This type of antenna geometry enjoys a better signal-to-noise ratio (SNR) as compared to thin-wire antenna. We develop the circuit model of this type of nanotube antenna, in which quantum capacitance and kinetic inductance are incorporated, along with magnetic inductance and electrostatic capacitance. Hallen's-type integral equation is derived to examine and describe the performance of such an antenna. Performance parameters, such as antenna efficiency, radiation resistance, input resistance and reactance are calculated. The models for far-field and near-field antenna patterns are also developed.

8:15 NANO-BIO OPTICAL FIBER SENSORS FOR HUMAN BREAST CANCER CELLS AND DNA DETECTION BASED ON LASER INTUCED FLUORESCENCE

Chan Kyu Kim (1*), Rajamohan R. Kalluru (1), Fang Y. Yueh (1), Jagdish P. Singh (1), Scott T. Willard (1), Alicia N. Musselwhite (1), and Paresh C. Ray (2), (1) Mississippi State University, Mississippi State, MS 39762 and (2) Jackson State University, Jackson, MS 39217

Two different optical bio-sensors are being developed for human breast cancer cells and DNA detection. First biosensor employs laser induced fluorescence (LIF) technique to obtain standard Human breast cancer cell LIF spectrum. The LIF spectra of the cancer cell treated with 4-hydroxytamoxifen are also collected and compared with the standard LIF spectra of breast cancer cell lines to study the reaction of cell by chemical treatment. The bio-sensors have the capability to distinguish from the standard LIF spectra of human breast cancer cells to the LIF spectra of the cancer cell by treated 4-hydroxytamoxifen. Second bio-sensor used LIF quenching technique by gold nanoparticles for the detection of single-strand (ss) DNA hybridization. In this work, the fabrication of a miniaturized, inexpensive and battery operated ultra-sensitive LIF optical fiber sensor was developed. Fluorescence was induced by a battery operated laser pointer in the second case. Compact architecture of the designed sensor along with the carefully aligned optics, offers a cost effective solution to detect single base-mismatch DNA. A unique data processing technique has been developed to analyze the recorded data for identification and differentiation in both configurations.

8:30 SLURRY PRODUCT ANALYSIS WITH LASER INDUCED BREAKDOWN SPECTROSCOPY

Seong Yong Oh*, Fang Y. Yueh, and Jagdish P. Singh, Mississippi State University, Mississippi State, MS 39762

Laser-induced breakdown spectroscopy (LIBS) is an analytical tool that has the ability to provide simultaneous multi-elemental composition for solids, liquids and gases sample. LIBS technique exploits high-energy laser pluses to create the micro-plasma plume on the surface of material. Atomic emission spectra directly collected from micro-plasma plume is utilized for determining the elemental composition of the sample. Integration with the optical fiber, no sample preparation, and quick on-line elemental analysis are the main advantages of the LIBS probe, which make it practicable to apply in the inaccessible place. However, it is a challenging work to apply LIBS technique to slurry analysis due to its sedimentation, splashing by the laser induced shock on the slurry's sample surface and fluctuation in lens-to-sample distance (LSTD). To overcome those technical problems associated with LIBS measurement of the slurry sample, a slurry circulation system was newly designed. LIBS measurements of slurry samples were optimized by varying the experimental parameters such as the pulse repetition rates of laser and the detector gate time delay and width. The calibration curves for different elements were obtained and studied towards improving the LIBS analysis result. The configuration design of slurry circulation system for LIBS measurement and other results will be presented in the paper.

8:45 TEMPERATURE SENSING USING FIBER GRATING LOOP RINGDOWN TECHNIQUE

Armstrong Mbi* and Chuji Wang, Mississippi State University, Mississippi State, MS 39762

A new method to develop fiber optic temperature sensors with an off-the-shelf fiber grating, using Fiber Grating Loop Ringdown (FGLRD) technique is presented. The prototype sensor consists of a diode laser source, a photodetector, an electronic control portion, and a fiber grating written in a section of a single mode fused silica fiber loop. With this novel method, temperature measurements are converted to a characteristic measuring time constant called the ringdown time. Two types of sensors are developed; the Type I sensor using a bare fiber Bragg grating (FBG) as the sensing element demonstrates a measurement resolution of 0.18[degrees]C (3- & sigma), and the Type II sensor using a long period grating (LPG) as the sensing element exhibits a thermal response up to 1000[degrees]C and excellent operation in 21-450[degrees]C. Additionally, a theoretical model of a Double Fiber Loop Ringdown (DFLRD) Temperature Sensor for simultaneous temperature sensing in separate locations is introduced. This work demonstrates a new generation of optical fiber sensors for remote sensing in harshest environments. This research is supported in part by US Department of Energy, National Energy Technology Laboratory, Grant # DE-RQ26-05NT500832 and National Science Foundation, Grant # ATM-0352926.

9:00 SOOT MEASUREMENT IN A HYDROCARBON ROCKET ENGINE WITH LASER INDUCED INCANDESCENCE

Kemal Eseller (1*), Fang Y. Yueh (2), Rajamohan R. Kalluru (2), Jagdish P. Singh (2), Olin P. Norton (2), and Robert L. Cook (3), (1) Mississippi State University, Mississippi State, MS 39762, (2) Institute for Clean Energy Technology (ICET), Starkville, MS, and (3) Center for Advanced Energy Conversion (CAEC), Starkville, MS 39759

This research project is focused on a technique which can provide non-intrusive quantitative measurement of soot on a large-scale rocket engine plume and provides a unique diagnostic tool to characterize engine performance. Laser Induced Incandescence (LII) imaging is developed, and applied on soot particles to measure the particle size and density. LII sensor, as an analytical model, is useful for developing various rocket engines, understanding of soot formation and the oxidation process in the combustion. LII system has been set up to detect LII signals which are emitted by soot particles. LII signal was produced by a frequency-doubled pulsed Big Sky Model CFR 400, Nd:YAG laser (532 nm, 200 mJ, 9-mm diameter), and it was detected by a 0.5m spectrograph (Spex 500M, 2400 1/mm grating) through a UV grade optical fiber and photomultiplier tube. The effects of experimental parameters such as laser fluence, gate delay, gate width and the effect of the focusing laser beam on the LII signal were investigated to determine the optimum LII experimental condition.

9:15 ADAPTIVE POWER CONTROL PROTOCOL FOR MULTI-CARRIER WIRELESS COMMUNICATION SYSTEMS

Ibrahim Y. Abualhaol*, Mustafa M. Matalgah, and Atef Z. Elsherbeni, University of Mississippi, University, MS 38677

The transmission power in any communication system is a valuable and limited resource. In many scenarios, the received instantaneous signal-to-interference-plus-noise ratio (SINR) might be less or more than a required value to achieve certain quality of service (QoS). In adaptive modulation and coding wireless communication systems, multi-rate transmission is supported depending on the received SINR. To achieve a certain transmission rate, SINR has to be within a predefined interval of service. Near-SINR-threshold based adaptive power control protocol (APCP) is suggested to be used in adaptive modulation and coding multi-carrier wireless communication system to maximize the system throughput and/or save the transmission power. The main idea of this protocol is to change the transmitted power over each sub-channel such that the received SINR lies near the lower threshold of the interval of service. When the SINR is near the upper threshold of the interval of service, it is obvious that we can save some power by decreasing the transmitted power down to just above the lower threshold. The excess power can be saved if the target is to increase the battery life. If the application needs higher transmission rate we increase the transmission power over some other sub-channels in order to operate with a higher modulation/coding order.

9:30 PASSIVE MICROSTRIP RESONATOR FOR CHIP-LESS RFID TAGS

Chye Hwa Loo*, Atef Z. Elsherbeni, and Fan Yang, University of Mississippi, University, MS 38677

This work presents an implementation of a completely passive chipless radio frequency identification (RFID) tags as low-cost alternatives to chip-based RFID tags. In view of the fact that microstrip resonators exhibit electromagnetic resonance behavior, capturing a frequency response of a material structure with a microstrip resonator can be accomplished with very little transmitted energy. The proposed design uses microstrip planar structures with multiple variation resonant frequencies to accumulate digital information into the resonant structures. As an example, such resonant structures can be designed to handle the 96-bits electronic product code (EPC) which replaces the barcode on goods in supermarkets. The tag is interrogated by the tag reader, and the electromagnetic response of the tag is detected as voltages or currents induced in the tag reader antenna. The frequency response of the tag contains features that are relatively easy to extract and can be collected by a variety of simple electronic hardware. The information is observed and processed in the frequency-domain. Nevertheless, the primary potential benefit of the proposed chipless tag is that it can be printed directly on products and packaging cheaply. Novel approaches of design theory including a circuit model for a multiple-resonant structure will be presented.

9:45 Break

10:00 SUPERHEAVY NUCLEI: A SEARCH FOR ISLAND OF STABILITY

Anatoli Afanasjev, Mississippi State University, Mississippi State, MS 39762

Recent discovery of the element 118 (proton number 118) by the group of Russian and American scientists considerably increased the interest to the properties of superheavy nuclei (nuclei with proton number larger than 100). These nuclei are stabilized only by the quantum effects. In my presentation, I will consider these nuclei in the framework of the relativistic mean field theory. In this theory, the nucleus is described as a system of nucleons interacting by the exchange of different mesons. Special attention will be paid to self-consistency effects in these nuclei and to the differences in theoretical predictions.

10:15 SMALL WORLD CARBON NANOMATERIALS: DENSITY FUNCTIONAL THEORY SIMULATIONS

Jeremy Yancey*, Mark A. Novotny, and Steven R. Gwaltney, Mississippi State University, Mississippi State, MS 39762

The possible existence of small, pure carbon molecules based on physical small-world networks is addressed using density functional theory calculations. A ring of atoms with one or more small-world connections between pairs of non-nearest-neighbor sites was chosen for the network topology. The small-world connections are made with and without additional carbon atoms placed along the link. The energy per atom of these small-world carbon systems is compared with benchmark carbon clusters such as the [C.sub.20] ring, bowl, and cage isomers, the [C.sub.60] Buckyball, monocyclic pure carbon rings ranging from [C.sub.4] to [C.sub.48], bare linear carbon chains ranging from [C.sub.2] to [C.sub.48], fullerenes ranging from [C.sub.20] to [C.sub.60], and various all-carbon graphitic fragments. The energy per atom results for these materials provide an indication that some of these pure-carbon small-world nanomaterials are reasonable for real world synthesis.

10:30 PROBABILITY OF ERROR BASED CHANNEL STATE DETECTION PROTOCOL FOR UPDATING CHANNEL STATE INFORMATION IN WIRELESS COMMUNICATION SYSTEMS

Ibrahim Y. Abualhaol* and Mustafa M. Matalgah, University of Mississippi, University, MS 38677

The signal-to-interference-plus-noise ratio (SINR) or the channel state information (CSI) is important for the transmitter and receiver to monitor the quality of the received signal and to determine the appropriate transmission power and modulation/coding order in adaptive wireless communication systems. The CSI is used to improve the performance of the system in terms of probability of error (PER) and probability of outage. In this work, we develop a protocol based on probability of error and called channel state detection protocol (CSDP), This CSDP uses a predefined trial sequence to estimate the CSI. The received trial sequence is compared with the same known sequence at the receiver end, then the instantaneous PER is calculated. The CSDP protocol maps the calculated PER for certain modulation into the corresponding SINR which represents the instantaneous CSI. The advantage of evaluating SINR using this technique is that it does not require any analog devices to measure the power of the received signal nor does it require specifying pilots to measure the received power. This protocol works for any wireless communication system over any fading environment.

10:45 THE SEARCH FOR A COSMOLOGICAL STANDARD CLOCK IN GAMMA-RAY BURST TIME PROFILES

John Patrick Lestrade*, Jane Harvill, Ionna Banicescu, and Ricolindo Carino, Mississippi State, MS 39762

Of the more than 3,000 gamma-ray bursts detected over the past 35 years by various experiments flown in space, redshifts have been measured for a little more than two dozen. These redshift data indicate that the sources of these explosions are spread out over distances of many billions of lightyears. At these distances, we would expect the Hubble flow to impress a (1+z) stretching on the temporal properties of bursts. Unfortunately, due to the very large dynamic range of grb time profiles (durations range from 10's of milliseconds to 10's of minutes), it has been very difficult to detect any relativistic time dilations in the grb observations. Two of the early attempts were Lestrade et al. (1993, Astron. & Astrop Supp. Ser., 97, 79) and Norris et al. (1994, Astrop. J, 424, 540). In this paper we fit a nonparametric family of autoregressive models to the time profiles in the search for a more reliable standard clock.

11:00 SMALL-SIZE DOUBLE SIDED ROUNDED BOWTIE ANTENNA ARRAYS FOR UWB APPLICATIONS

Tutku Karacolak* and ErdemTopsakal, Mississippi State University, Mississippi State, MS 39762

UWB systems require compact and extremely wide band antenna design covering the spectrum from 3.1 GHz to 10.6 GHz. High gain and phase linearity are also desired in such systems. Compared to a single antenna, antenna array systems significantly enhance the overall system performance, in terms of capacity and spectrum efficiency achieving high data rate service. Improved directivity and beam scanning are added advantages of array systems. In this study, double sided rounded bow-tie antenna arrays are considered. Each array element has two identical symmetric patches with one patch located on the front side of the substrate and the other on the back side. The antenna covers the UWB spectrum, and has also omni-directional radiation characteristics with reasonable gain values over the same frequency band. Different array configurations are presented in order to improve the pattern stability. The coupling effect between elements is investigated since coupling is a significant parameter in the array performance. Two, four, and six element linear arrays are designed with feeding networks for various steering angles. The maximum radiation is steered in different directions to form a scanning array by controlling the progressive phase difference between the elements. Measurements and simulations regarding antenna parameters such as S-parameters, radiation pattern, and gain will be presented. Results for different angles of phase shift between the elements will be also presented.

11:15 LASER RAMAN OPTICAL SENSOR FOR MONITORING QUALITY OF LIQUID OXYGEN

Appolinaire Luanje (1*), Rajamohan R. Kalluru (2), Fang Y. Yueh (1), Jagdish P. Singh (1), (1) Mississippi State University, Mississippi State, MS 39762 and (2) Mississippi Ethanol LLC, Winona, MS 38967

An integrated fiber optical Raman sensor is designed for real-time non-intrusive detection of liquid nitrogen in liquid oxygen (LOX) at high pressure and high flow to monitor the quality of LOX used during the testing of the rocket engine. This sensor can also be used to monitor the chemical composition in large chemical reactors to provide data to optimize the efficiency of the processing plant and to control the chemical process in the plant. The integrated sensor employed a hight power (3W) solid state pumped Nd:YAG frequency doubled 532nm laser, InPohotonics Raman probe inbulit Raman signal filter optics, high resolution miniature spectrometer, and Photomultipler tube with selected band pass filters to collect N2 and 02 Raman signals respectively. We report the improved performance of the sensor in estimating the ratios of nitrogen and oxygen in gas and liquid mixtures.

11:30 METALLIC PHASES IN ONE DIMENSIONAL MOLECULAR CONDUCTORS

Rahul Hardikar* and R. Torsten Clay, Mississippi State University, Mississippi State, MS 39762

In many organic conductors and superconductors internal vibrations (phonons) of the molecules making up the crystal are strongly coupled to the conduction electrons and have large effects on the electronic properties of the materials. The crystal structures of many of this class of materials are very anisotropic with conduction along essential a one-dimensional (1D) crystal axis. One great challenge in theoretical description of such materials is to describe why metallic or superconducting phases are often found close to insulating phases with unusual magnetic, electronic, or structural properties. We present a numerical study of the Hubbard-Holstein Model (HHM), one of the simplest models to incorporate the interaction of the vibrations with the conduction electrons. Previous theoretical studies of the HHM at half filling (one conduction electron per molecule in the crystal) predict that only insulating phases are possible. Our numerical results show that there exists an intermediate metallic phase whose size is dependent on the vibrational frequency of the phonons. This gives one possible mechanism that can explain why superconductivity is typically found adjacent to ordered insulating phases.

11:45 PERFORMANCE ANALYSIS OF WIDEBAND MULTI-STANDARD SOFTWARE DEFINED RADIO BASE STATION RECEIVERS WITH INTER MODULATION DISTORTION

AbdulKhaleq Mohammed* and Mustafa M. Matalgah, University of Mississippi, University, MS 38677

Software defined radio (SDR) base stations are designed to provide improved mobile communications with global roaming. In order to achieve this goal, SDR base station must be able to support multiple mobile communication systems standards. It is expected that the dynamic range of the signal received at the SDR base station is very high. This high dynamic range of the signal has huge impact on various performance metrics such as signal-to-noise ratio (SNR) and Spurious Free Dynamic Range (SFDR). Most recent work has focused either on improving the resolution of Analog to Digital Converter (ADC) or evaluating the performance metrics mentioned above to implement SDR base station practically. SDR receiver deals with a wideband signal with high dynamic range. One parameter that can influence the performance of SDR base stations is Intermodulation Distortion (IMD) which arises due to the presence of large number of uncorrelated carriers in a wide band signal. The IMD is an In-Band Distortion to the system and is characterized by a parameter called Noise Power Ratio (NPR). Previous works have shown to relax the rigorous resolution requirements of SDR base station ADC by using methods such as the Adaptive Prediction and Digitization Cancellation (APCD) technique. These methods have overlooked the gravity of a wideband distortion like the IMD which can be very significant in SDR. In the present work we quantitatively analyze the performance of APCD-based receivers taking into account the IMD, and hence quantitatively measure the deterioration in performance.

FRIDAY AFTERNOON

Bost Theater

1:00 EFFECTS OF MECHANICAL STRAIN ON RAT BONE MARROW CELLS GROWN ON TITANIUM VERSUS THERMANOX

Marcia Lee* and Joel Bumgardner, Mississippi State University, Mississippi State, MS 39762

Metal alloys are widely used in orthopedic applications. Tissue culture models have been used with different material substrates to study the response of bone cells subjected to mechanical strains in order to gain insight into the cellular event sequence leading to osseointegration of an implant to the surrounding bone tissue. Our hypothesis was the response of osteoblast cells subjected to mechanical strain is affected by the culture substrate. For cells mechanically strained under the same conditions, we expected to find different rates of cell proliferation and extracellular matrix synthesis for cells cultured on titanium versus cells cultured on tissue culture plastic (Thermanox). To test this hypothesis, rat bone marrow derived osteoblast-like cells were grown on titanium or Thermanox and subjected to mechanical strains of 400 or 1000 microstrains of tension. The response of the cells on the different substrates to mechanical strain was determined by measuring alkaline phosphatase (ALP) expression, calcium deposition, DNA quantification and total protein synthesis over a twenty-day period. This study demonstrated no significant differences in the rate of cell proliferation and synthesis of extracellular matrix on cells strained under the same conditions and grown on titanium or tissue culture plastic (Thermanox). Furthermore, the two strain levels did not have a significant effect on cell proliferation and extracellular synthesis as compared to the controls. Over the twenty-day period, ALP, total protein and calcium levels increased in strained and unstrained cells. DNA did not increase significantly in any of the three groups during this same time period.

1:15 VERY SMALL ULTRA-WIDEBAND DOUBLE-SIDED EXPONENTIALLY TAPERED SLOT ANTENNA ARRAYS

Aaron Hood* and Erdem Topsakal, Mississippi State University, Mississippi State, MS 39762

The double-sided dual exponentially tapered slot antenna (DETSA), sometimes referred to as an antipodal Vivaldi antenna, has demonstrated a measured bandwidth of more than 40 GHz in past studies. While the antennas used to achieve these results are typically greater than 10 cm in length, our research has determined that antennas fabricated with dimensions less than 4cm x 4cm can easily exceed the range required for emerging ultra-wideband technologies (3.1-10.6 GHz). The antennas maintain approximately 4 dB of gain across the entire band with patterns directed along the main axis. By creating an array of these elements, the efficiency of the antenna is improved, and features such as beam scanning are possible with a two-element configuration improving the gain by a minimum of 2 dB. Coupling between the elements is an important consideration in array design as high coupling levels may result in unsatisfactory performance. A two-element DETSA array has been found to have an average coupling of -25 dB across the UWB spectrum. Various configurations of two and four elements are considered with feeding networks designed to provide different steering angles by controlling the phase difference between the elements. Simulated results are confirmed through careful measurements of the antenna parameters including S-parameters, radiation pattern, and gain.

1:30 SEAWULF: DESIGN OF A BEOWULF CLUSTER FOR THE PROCESSING OF SEISMIC DATA

Maxwell Woolsey* and Thomas M. McGee, University of Mississippi, University, MS 38677

A Beowulf cluster nicknamed "Seawulf" was designed for the processing of seismic data from an undersea gas-hydrates monitoring station. The project is funded by a grant from the Department of Interior, Minerals Management Service. Seismic data, by nature, can be processed in a data parallel manner. It consists of traces of acoustic data which may be divided among a number of processing nodes. The design of the Seawulf is typical of a Beowulf cluster in that it has a master node which generally controls operation of the cluster as well as external communication, and a number of nodes that each process a data subset. Common layouts for clusters include large racks of computers in tower cases as well as compact commercial units which enclose processing nodes in a small space. The former configuration produces a physically large cluster, in which each node has an enclosure and a power supply. The latter can provide an extremely dense unit, often taking advantage of proprietary hardware including shared power supplies and high-speed networking connectivity. This performance, however, comes at a high price. The Seawulf is a hybrid consisting of off-the-shelf hardware in a custom designed enclosure with external recirculating air-cooling system and shared ATX power supplies. The Seawulf is expandable to 64 micro-ATX processing nodes combining the best of both standard topologies.

1:45 STUDY ON THE WALL INSULATION IN INVERTER-FED DRIVE

Pavel Trnka, University of West Bohemia, Czech Republic and Mississippi State University, Mississippi State, MS 39762

The voltage waveforms generated by power frequency converters affect significantly the reliability of drive wall insulation. A power inverter produces modulated voltage on its output which contains square-shaped voltage impulses with fast rise times. The problem is to predict the machine wall insulation lifetime, when it operates as a part of the power inverter fed drive. The main goal of the research project was to provide quantification of the wall insulation reliability decrease. Four the insulation systems were aged both by the AC 50 Hz voltage and high frequency pulse voltage. The life time curves have been evaluated and simple mathematical models have been employed to show the wall insulation reliability decrease. Two different shapes of the wall insulation samples were tested. The results obtained during measurement on flat samples and "dog-bone shape" samples were compared. The results of the test showed great difference between the two applied voltage shapes. Significant decreases in the times to breakdown of all four materials by the high frequency pulse voltage aging were observed. The tests proved that the resistance of the stress grading coatings has to be changed when used in power inverter fed drive. The comparison of the result obtained by the testing of different shaped samples proved the possibility to use flat samples. This shape of samples has the advantage during the measurements. The results from this research project are now used for the creation of the on-line monitoring system of the wall insulation in power inverter fed drive.

2:00 SIMULATION AND PERFORMANCE EVALUATION OF PATH LOSS RECOVERY PROTOCOL FOR UNMANNED AIRBONE VEHICLE

Omar Hammouri*, Ibrahim Y. Abualhaol, Mustafa M. Matalgah, and Atef Z. Elsherbeni, University of Mississippi, University, MS 38677

During the design of any transportation system, path planning is usually a recognized problem. It becomes significant when recovering the path of autonomous unmanned airborne vehicles (UAV). Path loss could be defined as the failure of a UAV to communicate with the ground control unit (GCU). In most cases, communication loss occurs due to the insufficiency in the UAV resources to satisfy the required minimum transmission rate. This could be the result of environmental and/or interference conditions, which decrease the received signal-to-interference-plus-noise ratio (SINR). The solution to these problems can be based on the path loss recovery protocol (PLRP) which is a mechanism to deviate the UAV from its current un-recognized trace in order to recover its communication with the GCU. The new subsequent trace-point is sought to experience better SINR, through either being on a line of sight or within less range from the GCU. In this research, the PLRP, applied to an adaptive modulation and coding system, is modeled and simulated using the Simulink software package. The performance of the PLRP is evaluated by assuming a certain mission path with scattering attenuation (simulated weather conditions), as well as instantaneous co-channel interference (neighboring UAVs). The out-of-service percentage, bandwidth, power consumption, and data rate are the main metrics used to assess the enhancement gained by the PLRP.

2:15 DEVELOPMENT AND TESTING OF MEAM POTENTIAL FOR AL-MG ALLOYS

Bohumir Jelinek (1*), Jeffery Houze (1), Sungho Kim (1), Seong-Gon Kim (1), Mark Horstemeyer (1), and Michael Baskes (2), (1) Mississippi State University, Mississippi State, MS 39762 and (2) Los Alamos National Laboratory, Los Alamos, NM 87545

A MEAM potential for Al-Mg alloys was developed based on the elastic and structural properties determined from ab-initio calculations. Transferability of the new potential was tested by comparing various bulk, surface, and point defect properties with ab-initio simulations. Volume-energy dependence of Al and Mg in fcc, hcp, bcc and simple cubic crystal structures from MEAM and ab-initio simulations was determined. Heat of formation for A1-Mg crystals in C1, C3, C9, C15, D[0.sub.3], D[0.sub.9], A12, A15, L[1.sub.2], B1, B2, and B3 was calculated using both methods. Surface formation, stacking faults, and adsorption energies were compared. For point defects calculations, a close agreement of vacancy formation energies, interstitial and substitutional point defect energies was found.

2:30 LIGHT FROM A DOPPLER-BROADENED GAS OF ATOMS

John T. Foley, Mississippi State University, Mississippi State, MS 39762

In a gas of atoms at low pressure, the light emitted by each atom has its frequency shifted by the Doppler effect. In this talk computer simulations of the components of the total electric field vector from such a gas of atoms are presented. It is shown that at an observation point far from the atoms, each electric field component is a succession of wavepackets whose amplitudes and phases fluctuate on a time scale of the order of the reciprocal of the bandwidth of the light. It is also shown that the polarization of the light fluctuates on this same time scale.

2:45 MOLECULAR DYNAMICS SIMULATIONS OF CRACK NUCLEATION NEAR NANOPARTICLE INCLUSIONS

Jeffery Houze*, Bohumir Jelinek, and Seong-Gon Kim, Mississippi State University, Mississippi State, MS 39762

We studied nucleation of cracks near a nanoparticle embedded in a matrix under tension with molecular dynamic simulations using Modified Embedded Atom Method (MEAM) potentials for Al and Mg. Uniaxial tension was applied to an Al(fcc) matrix containing an embedded Mg(hcp) nanoparticle. The same study was performed with an Al nanoparticle embedded in a Mg matrix. Animations showing the damage evolution in both alloying situations and the effect of the materials different tensile strengths on crack nucleation will be presented.

3:00 Break

3:15 GAMMA RAY BURST HARDNESS AS A FUNCTION OF TIME AND INTENSITY

Phillip Durst* and John Patrick Lestrade, Mississippi State University, Mississippi State, MS, 39762

Gamma Ray Bursts (grb) are high-energy explosions happening at cosmological distances. While the cause of GRBs is still largely a mystery, numerous experiments have been undertaken to explore their intrinsic properties. In this study we present our analysis of the evolution of burst hardness. Here hardness in a burst is defined to be the number ratio of high energy (> 100 kev) photons to total photons received. We divide each GRB time profile into variable size time bins based on the standard deviation (sigma) of the gamma-ray background. The width of each bin is the minimum width that contains an accumulated countrate of at least 100 sigma. This ensures good statistics as well as a finer time resolution when the burst is brightest. Zone hardness can then be presented as a function of intensity and time relative to burst trigger. Our preliminary results show that hardness decreases with time during a burst pulse and drops below that of the ambient gamma-ray background for a short interval. This latter effect is primarily due to the well-known time lag between hard and soft grb photons. In the case of hardness versus average zone intensity, our early results show a significant positive correlation. These latter results are in agreement with Borgonovo and Ryde (2001, Astrop. J, 548, 770).

3:30 HIGH-K BANDS AND GAMMA-RAY DIRECTIONAL ANGULAR CORRELATION MEASUREMENTS IN [.sup.168.Hf]

Ram Yadav (1*), Wenchao Ma (1), H. Amro (1), P.G. Varmette (1), G.B. Hagemann (2), B. Herskind (2), G. Sletten (2), R.V.F. Janssens (3), B. Million (4), and H. Hubel (5), (1) Mississippi State University, Mississippi State, MS 39762, (2) Niels Bohr Institute, Copenhagen, Denmark, (3) Argonne National Laboratory, Argonne, IL 60439, (4) Universita di Milano, Milan, Italy and (5) University of Bonn, Bonn, Germany

[.sup.168.Hf] is the first nucleus where triaxial superdeformed structures were found. We have now further observed three High-K bands in it employing the [.sup.96.Zr]([.sup.76.Ge],4n) reaction. Two data sets were obtained from experiments at Argonne National Laboratory. The decay [gamma]-rays were measured with the Gammasphere Compton-suppressed Ge spectrometer array. A self-supporting [.sup.96.Zr] foil (thin target) was used in the first experiment, while in the second experiment the [.sup.96.Zr] target material was evaporated onto a thick Au backing (backed target or thick target). Three-and four-dimensional histograms (cube and hypercube) were constructed for [gamma]-ray coincidence analysis. Coincident spectra were studied using the software package RADWARE. Three previously unknown High-K bands were identified and placed in the level scheme. Spins and parities of levels in the High-K bands were proposed according to measured directional angular correlations of decay [gamma]-rays. Based on our Cranked shell model calculations and a systematic comparison with neighboring nuclei, possible intrinsic configurations were suggested for the High-K bands and have been confirmed from gyromagnetic ratios measurement. The lifetime measurements for [.sup.168.Hf] is in progress to establish the deformations. Work supported by U.S. DOE under grant DE-FG02-95ER40939.

3:45 IMPROVING THE VARABILITY-LUMINOSITY CORRELATION FOR GAMMA-RAY BURSTS

Shane Creel* and John Patrick Lestrade, Mississippi State University, Mississippi State, MS 39762

Gamma-ray bursts (grb) are the most luminous explosions since the Big Bang. However, other than saying that they are extragalactic, it has been practically impossible to determine the distances to their sources. Recently, Li and Paczynski (2006, Astrop. J, 366, 219), using the data from the two dozen grb whose luminosities and distances are known, have shown that grb time-profile variability is correlated with burst luminosity, implying that grb might be standard candles. The hope is that if indeed burst luminosity can be deduced from the variability, that plus the apparent brightness yields the distance. The \"variability\" of a burst profile, its twinkling, can be defined in many ways. While the method they use works for two dozen bursts, perhaps there is a more robust definition that will work for the larger database. In this paper, we present new methods of calculating the variability of grbs in order to improve the tightness of the correlation.

4:00 MOLECULAR DYNAMICS SIMULATION OF SINTERING OF NANOPOWDERS

Amitava Moitra*, Sungho Kim, and Seong-Gon Kim, Mississippi State University, Mississippi State, MS 39762

Nanopowder metallurgy is an emerging technology that fabricates sophisticated metal parts by sintering of nano-scale metal powders. Consolidated nanopowders are known to have enhanced mechanical properties compared to conventional micron-size powders. Nanopowders also offer the promise of improving the sintering process since, due to their higher surface area to volume ratio; they can be densified more fully and much quicker resulting lower sintering temperature and higher fracture toughness. To understand the fundamental mechanisms of sintering of nanopowders, molecular dynamics simulations of tungsten nano-particles were performed using the Modified Embedded Atom Method (MEAM). The effects of various heating cycles on sintering process as a function of size of the nanopowders will be presented.

4:15 DC PROTECTION FOR NAVAL SHIPBOARD POWER SYSTEMS

Hymiar Hamilton* and Noel Schulz, Mississippi State University, Mississippi State, MS, 39762

The need for DC power at continuous uninterrupted rates is a reality for ship survival during highly intense combat and regular travel. One newly proposed distribution system on the all electric ship is designed using a DC distribution method (zones) in which the use of transformers and frequency issues/manipulation can be eliminated with the use of power electronics. These power electronic devices can simplify the system providing more space, possible cost reduction, and variable control. Our main key objective is ensure that the DC buses/systems and converters/rectifiers are protected from faults, transients, and other malicious events that can cause unwanted interferences, shutdown, and possible damage or destruction. DC faults can have a detrimental impact on the ship performance. DC protection should allow for high speed and high sensitive detection of faults enhancing reliability in the supply of electric power. The simulations have shown our developed method of zero crossing can detect a DC fault and perform a shutdown on the line/bus without having to open a circuit breaker and return to normal operating conditions once the fault is removed. The use of power electronics and DC fault detection methods can be employed to solve how to protect the system's stability and longevity.

4:30 DEVELOPMENT OF AN ADAPTIVE PROTECTION SCHEME FOR NAVAL SHIPBOARD POWER SYSTEMS

Oluwaseun Amoda* and Noel Schulz, Mississippi State University, Mississippi State, MS 39762

Future naval ships will be all-electric, with an integrated power systems that combines the propulsion power system with the rest of the ship's electrical distribution system. Reconfigurations schemes are being developed for the Shipboard Power System to increase fight-through and survivability of these electric ships. An adaptive protection scheme named, X Adaptive Protection (XAP) is being developed for the DDX power system. XAP will use the status of breakers to determine the configuration of the system in real time. XAP will then perform fault analysis on the determined configuration. It will then use the result of the fault analysis and power flow levels to set the protection levels of the system.

4:45 INTELLIGENT PLACEMENT OF METERS FOR SHIPBOARD SYSTEM ANALYSIS

Sandhya Sankar* and Noel Schulz, Mississippi State University, Mississippi State, MS 39762

Real time monitoring of the shipboard power system is a complex task to address. Unlike the terrestrial power system, the shipboard power system is a comparatively smaller system but with more complexity in terms of its system operation. This requires the power system to be continuously monitored to detect any type of fluctuations or disturbances. Planning metering systems in the power system of a ship is a challenging task not only due to the dimensionality of the problem, but also due to the need for reducing redundancy while improving network observability and for efficient data collection for reliable state estimation purposes.

The research is geared towards the use of a genetic algorithm for intelligent placement of meters in a shipboard system for real time power system monitoring taking into account different system topologies and critical parameters to be measured from the system. The algorithm predicts the type and location of meters for identification and collection of critical measurements. The algorithm is tested with different system topologies. The results have shown that genetic algorithm is a useful tool for planning the metering system in an electric ship.

5:00 Divisional Business Meeting