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Ergonomics in poor hand tools design and muscoskeletal disorders of workers during various working environment.

INTRODUCTION

Human factor & ergonomics which involves employability of occupational health, safety & productivity in industry. It involves various concepts starting from safe furniture, easy use of machines, equipment, body positive, Design and Legal station etc.,. If employer is fit, their involvement in work leads to high productivity. This paper will discuss about handling of poor tools cause of various work- related injuries and muscoskeletal disorders, strain injuries & disorder to workers during the workplace are measured. Measurement of body segments orientation and pressure distribution of human body and muscle reactions forces and vibration forces will measure and avoid the workers from various fatigue factor and injuries with help of ergonomics design considerations

II Literature survey based on Ergonomics in hand tools design & Muscoskeletal disorders of workers during various working environment:

Thomas W. Mcdowell et. al discussed measuring grip strength of the instrument. This study utilized a recent grip dynamometer design along with the Jamar dynamometer to further examine these relationships. The objective of this study was to compare how changes in grip size affects grip strength measured with each dynamometer style. Results confirm that handle size significantly affects the applied grip strength measured with both types of grip dynamometer. [1]

Raymond W. McGorry et. al discussed about with how the handle affect on muscle oxygenation and blood volume in the extensor carpi radialis and the flexor digitorum super ficialis during rhythmic isometric gripping tasks. Power grip contractions were performed at 15% of maximum voluntary contraction (MVC) at a work rest cycle of 10-5-s, with three different handles (30, 40, and 50 mm) for a period of 15-min. Significant interactions between handle diameter and muscle groups in TOI and cHb, were also observed, implying differential contributions of the flexor and extensor muscles. The results suggest that for the hand-handle interface it is not only important to consider handle diameter, but also perfusion of both flexor and extensor muscles. [2]

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Mahmut Eksioglua and Kemal Kizilaslan discussed about the study of steering- wheel grip force male and female drivers driving an automobile on two different road conditions (smooth and rough asphalt) at two different speeds .from this study was conducted to collect steering-wheel grip force data from everyday drivers while driving in different road conditions and speeds. A custom-made capacitive pressure distribution pad wrapped around the steering wheel was used as the measuring device with custom written software. The results of this experiment showed that the males apply significantly higher absolute and net steering-wheel grip forces. However, both genders, on the average, apply similar relative grip forces for the all driving conditions studied. [3]

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Zulquernain Mallick discussed about Hand-arm vibration syndrome (HAVS) is very common among workers operating power tools and performing similar work for extended period of time. In this study the influence of handle-hand interaction of a grass trimming machine (GTM) is evaluated based on different hand positions of operator during operation. Besides, several operating parameters (length of nylon cutting thread, engine speed and sway angle) are investigated in terms of HAV. Three handle-hand positions (HHPs) are studied that are generally adopted by the GTM operators during their work. Experiments are carried out for measuring hand vibration using a tri-axial accelerometer conforming the effectiveness of this approach. Through this study not only the optimal operating parameter levels for GTM are obtained, but also the main process parameters that affect the HAV are determined. [4]

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Ming-Lun Lu et. al discussed the study evaluated thumb, hand forces, wrist, forearm and shoulder postures used for pipetting with three selected mechanical pipettes. Twelve pipette users in a large university health system participated in pipetting simulation in their own laboratories to investigate the effects of pipette type, body posture (standing/seated), sample volume (200/1000 ml) and pipetting task on the physical risk factors. Wrist and forearm postures were measured with an electrogoniometer and a torsi meter. The study results showed several advantages of using the non-axial pipette over the traditional axial ones. The non-axial pipette was associated with approximately 2-6 times less thumb and hand force than the traditional axial pipettes. This study may provide useful information regarding design of pipettes for reducing physical risk factors associated with pipetting. [5]

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Ignacio Ainsa et. al discussed about investigate which factors cause uncertainty in hand arm vibration evaluation and how much they contribute to the total uncertainty of the measurements The experiments were performed with handles belonging to real machines while being

Hand held by an operator. The results of this investigation show that the fixing method and the accelerometer behavior are the two main sources of uncertainty. The total uncertainty of the measurements in this work, considering both instrumentation and fixing method, reaches up to 8% of the values measured [6]. Yong-Ku Kong and Brian D. Lowe discussed and deals about The effects of gender, handle diameter (25-50 mm), and handle orientation (horizontal and vertical) on the perceived comfort, torque, total finger force, and efficiency of flexor and extensor muscle activity were examined in a maximum torque task. A 16-force sensor glove system was applied to measure finger and phalangeal forces, and a surface EMG was recorded to investigate muscle activities in the torque task. Output for the handle diameters (i.e., the efficiency increased when the handle diameter increased). 35-45mm handles were rated as the most comfortable for maximum torque exertions. According to a polynomial regression, 37-44mm and 41-48mm diameter handles (23.3% of the user's hand length) maximized perceived comfort and were thus recommended for females and males, respectively in this study [7].

Y. Aldiena et. al discussed about the distribution of localized pressure peaks and the resulting contact forces over the hand surface is investigated through measurements performed under applications of different combinations of hand grip and push forces in the 0-75N range. Three different cylindrical handles of 30, 40 and 48mm are used to measure the hand-induced forces and distributed pressures using a capacitive pressure-sensing mat wrapped around the handle. The peak pressures occurring in different regions of the hand surface are also derived and examined in view of the reported pressure-discomfort and pressure- pain threshold limits. The results show that contact pressures of considerable magnitudes develop within the hand-handle interface, while the magnitudes of peak pressures strongly depend upon the handle size, grip and push forces. The results also suggest that the mean peak interface pressure for a given handle size can be expressed as a linear combination of grip and push forces [8]. D. Welcome et. al discussed about study was conducted to develop a methodology for measurement of the contact force at the tool handle hand interface, and to identify the relationship between the contact force and the hand grip and push forces. A simulated tool handle fixture was realized in the laboratory to measure the grip and push forces using compression/extension force sensors integrated within the handle and a force plate, respectively. The hand-handle interface pressure data were analyzed to derive the contact force, as functions of the constant magnitudes of the grip and push forces, and the handle size. The results suggest that the hand-handle contact force is strongly dependent upon not only the grip and push forces but also the handle diameter [9].

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Jim R. Potvin et. al discussed about the purpose of this study was to compare the ergonomic demands associated with air and DC pistol grip hand tool use. Seven channels of EMG data were collected from 15 male and 15 female subjects to estimate the muscular demands on the forearms, biceps, shoulders and neck. An accelerometer was also used to estimate the torque reaction transmitted to the hand. Finally result shows for horizontal drilling, between waist and chest height, with torques not exceeding 7 Nm, pistol grip DC tools do not pose an additional risk of musculoskeletal injury to the upper limbs, when compared to pistol grip Air tools. In fact, for these conditions, the risk of upper limb disorders may be reduced through the use of pistol grip DC tools [10].

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Chih-Hung Chang and Mao-Jiun J. Wang discussed about study is to evaluate the influences of activation mode, torque and horizontal operating distance on hand-arm response while operating in-line pneumatic screwdrivers. Hand-arm response was investigated in terms of finger force exertion, flexor digitorum electromyography, and hand-transmitted vibration. Two activation modes (push to- start, and trigger-to-start), two torque levels (low, and high) and three horizontal operating distance (far, middle, and near) were evaluated. The results indicate that the use of push to-start mode, not only required a greater holding force involving forearm muscular exertion and middle, ring and small finger forces, but also incurred a greater hand-transmitted vibration than the use of trigger-to-start mode [11].

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Charlotte hall discussed about an interaction between hand size and strength of hand size, pressure-pain threshold (PPT) and hand strength were measured on 15 subjects. External pressure on the hand was measured, using small capacitive pressure sensors, while grasping cylinders (10-100 mm) and handling tools. Subjective ratings of cylinder preference, pressure, discomfort and pain were recorded. The result indicates that hand size is critical when the external force requirement is constant, while there is an interaction between hand size and strength when it varies. When gripping a cylindrical object, the fingers were exposed to the largest pressure. The gripping action was dependent on cylinder diameter, and the subjects strongly preferred cylinders with 30-40 mm diameter [12]. Jia-Hua Lin and Raymond W. McGorry ability to find out Powered hand tools have the potential to produce reaction forces that may be associated with upper extremity musculoskeletal disorders. In this study, subjective ratings of discomfort and acceptability of reaction forces were collected in an attempt to identify their associations with factors such as work location, and response covariates such as grip force and tool handle displacement The results indicate that normalized grip force during the torque buildup period was a significant factor for both subjective ratings. For the unacceptable torque reactions across the three tool configurations, the ratio of hand moment impulse over tool torque impulse was significantly greater than for the acceptable reactions. These models can further be used to establish exposure limits based on handle displacement and grip force [13]. Heecheon You et. al discussed the study evaluated two design modifications (rubber grip and torsion spring) to the conventional manual Cleco pliers by electromyography (EMG), hand discomfort, and design satisfaction. This study also surveyed workers' satisfaction with selected design features of the pliers for ergonomic improvement. The hand discomfort and design satisfaction evaluations identified that the grip span (max =14.0 cm) and grip force requirement (peak = 220.5 N) of the current pliers need ergonomic modification. The present study shows the needs of both the ergonomic design of a hand tool and the training of a proper work method to control work-related musculoskeletal disorders at the work place [14]

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Yuh-Chuan Shih to investigate the influence of splints without the volar parts as well as of forearm and wrist postures on grip performances including maximal volitional contraction (MVC), maximum acceptable sustained time (MAST), cumulated exertion output (CEO), and normalized exertion level (NEL). The results indicate that forearm posture is shown to be significant only on MVC. In addition, the effect of wrist posture cannot shift all responses, nor can the effect of splints. In general, a splint without volar part seems to be recommended while performing infrequent and forceful gripping tasks under the consideration of prevention [15].

Raymond W. McGorry discussed and describes a device for measuring gripping forces and the moments generated by a hand tool The device, configured as a boning knife, was sensitive to differences in grip forces and applied moments in a simulated meat cutting task requiring distinct levels of precision. Significant individual variation in the efficiency of grip force was also observed. Quantification of the forces applied with or by hand tools can be measured. However, there is sufficient knowledge of the primary physical risk factors to guide assessment and design of tasks assumed to pose excessive risk [16].

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Jouni Freund et. al discussed the effects of two ergonomic aids on the usability of an in-line screwdriver drove screws into horizontal plywood plates with four combinations of a screwdriver and an ergonomic aid. The activities of four forearm muscles (EMG) and the force acting on the screw were measured. The hand support and the sleeve had positive effects on the subjective perception of exertion and the surface texture, respectively. Differences in EMG and thrust force along the shaft of the screwdriver handle were found to be too small for reliable deductions in the effects of the ergonomic aids [17]. John Z. Wu et. al discussed about we hypothesize that the vibration power absorption density (VPAD) is a good measure for the vibration exposure intensity of the soft tissues of the fingers. In order to calculate the VPAD at a fingertip, we proposed a hybrid modeling approach, which combines a 2D finite element (FE) model with a lumped parameter model. This study that the proposed modeling approach can effectively take into account both local and global responses, such that the vibration-induced tissue stress, strain, and power absorption density in the fingertip, as well as the global driving point biodynamic can be predicted. The static stress and strain due to the static compression of the fingertip can also be predicted using this model. The proposed method is a practical and efficient approach to simulate the detailed biodynamic responses of a complex biological system in vibration [18].

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Jennie H. Donga and Ren G. Dong discussed the study it was hypothesized that the vibration-induced injuries or disorders in a substructure of human hand-arm system are primarily associated with the vibration power absorption distributed in that substructure the major objective of this study is to develop a method for analyzing the vibration power flow and the distribution of vibration power absorptions in the major substructures (fingers, palm-hand-wrist, forearm and upper arm, and shoulder) of the system exposed to hand-transmitted vibration. The result found that this study found that vibration power absorption is primarily distributed in the arm and shoulder when operating low-frequency tools such as rammers, while a high concentration of vibration power absorption in the fingers and hand is observed when operating high-frequency tools, such as grinders [19]

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Yuh-Chuan Shih and Mao-Jiun J. Wang investigate the various four handle shapes of the hand tools using in industries and also various glove materials and various handle diameters (circular, triangular, square and hexagonal), seven handle sizes, (25.4, 31.8, 38.1, 44.5, 50.8, 57.2 and 63.5 mm), and five types of gloves (surgical, single cotton, double cottons, leather and rubber) were tested for their effects on maximum volitional torque exertion (MVTE) for supination. The results can be applied to the design and selection of suitable hand tools for the purpose of reducing injuries and increasing productivity in industry [20]. Lawrence J.H. Schulze et al investigated the effects of pneumatic screwdriver characteristics and work piece orientation on operator productivity. Operators used four pneumatic screwdrivers (two pistol and two straight grip) representing two different clutch types (positive and automatic air shut-off). The two grip types represented both fast (1700 RPM) and slow (1000 RPM) motor speeds. The pneumatic screwdrivers were used at each of three different workstations representing different work piece orientations (horizontal work piece at a fixed height, horizontal work piece with an adjustable height, and angled work piece with adjustable height). The results of the study indicate that operators took longer to complete the required tasks and made more errors when the straight grip screwdrivers were used than when the pistol grip screwdrivers were used. These differences were more pronounced at the end of the task than at the beginning of the task [21]. David R. Burnett and Naira H. Campbell-Kyureghyan discussed and to identify and quantify scan-specific risk- factors for upper extremity work-related musculoskeletal pain in sonography. Seven subjects participated in the study which used a combination of self-reported and measured job analyses to specifically address risk-factors related to diagnostic medical sonography. 86% of sonographers reported upper extremity musculoskeletal pain. Ergonomic evaluation revealed that changes should be made soon. Finally determining the risk of musculoskeletal pain and in designing interventions to prevent or reduce the incidence of injury among sonographers [22]. Sukwon Kim et. al discussed the study was to quantify the lower extremity muscle strength characteristics of three age groups (young, middle, and the elderly) A commercial dynamometer was used to evaluate isokinetic and isometric strength at ankle and knee joints. This is especially true for the lower extremity strength measures in dynamic conditions.. The main objective of the study was to examine three different age groups' leg strengths, and, particularly, the study was interested in identifying differences in leg strength between a middle age adult group and a younger adult group. Additionally, leg strength of an older adult group was evaluated in order to emphasize the values in leg strength found in the middle-age group; the author thought that comparing older adults' leg strengths with middle-age group's leg strength would draw attention to the risk of injuries of middle-age workers. finally the These results suggested that, overall middle-age workers in the present study could be at a higher risk of musculoskeletal injuries [23].

Rebecca L. Brookham et. al discussed and study was to investigate the effects of a light hand tool exertion task on shoulder muscle activation during different postures of shoulder flexion and humeral rotation. The use of hand tools is linked with many cumulative trauma disorders of the upper extremity. results suggest that in order to reduce risky levels of inferior trapezius activation, light hand tool tasks (such as drilling) should be performed at neutral elevation and 45[degrees] internal rotation, or for slightly higher activations (but still low risk) at 60[degrees] shoulder flexion and 45[degrees] internal rotation. Relevance to industry. Identification of muscle activation patterns with respect to posture and hand and Identification of muscle activation patterns with respect to posture and hand forces during light hand tool tasks helps establish work layout geometries in job design and will provide the worker increased work endurance with lower risk exposures during task performance [24]. M. Grujicic et. al discussed about the long-distance driving fatigue experienced by vehicle drivers are investigated computationally using musculoskeletal modeling and simulation methods. A rigid-body model of a prototypical adjustable car seat is constructed as a part of the present work and combined with a public-domain musculoskeletal model of a seated human. Seated-human/car-seat interactions associated with typical seating postures of the vehicle driver are analyzed using the inverse-dynamics approach while the "minimum-fatigue" criterion is utilized to deal with the muscle redundancy problem. The results obtained show that various seat adjustments (e.g., back-rest inclination, seat-pan horizontal track position, etc.), driver's back supports (e.g., presence/absence of lumbar support) and the nature of seat upholstery (e.g., fabric vs. vinyl) can have complex influence on the muscle activation, joint forces, soft-tissue contact normal and shear stresses, all of which not only affect the comfort perception of the driver but also their feel of fatigue [25]. Magdalena Jaworek et. al deals about the study tested the hypothesis that burnout syndrome mediates effects of work-related factors, factors such as work demands and work stimuli, on the frequency of musculoskeletal complaints among hospital nurses. The sample was composed of 237 nurses from various wards across 4 hospitals located in southwestern Poland. Data was collected through three questionnaires. One of the questionnaires measured work- related factors and contained elements that afforded factor analysis. Results of structural equation modeling with a mediating effect showed that work demands were positively related to burnout syndrome and musculoskeletal complaints, higher work stimuli were associated with lower burnout, but with higher musculoskeletal complaints, and burnout was positively associated with musculoskeletal complaints [26].

Conclusion:

This present study shows the needs of both the ergonomic design of a hand tool and the training of a proper work method to control work-related musculoskeletal disorders at the work place. Conducted to develop a methodology for measurement of the contact force at the tool handle hand interface, and to identify the relationship between the contact force and the hand grip. Study was to investigate the effects of a hand tool exertion task on shoulder muscle activation and hand arm vibration during different postures of shoulder flexion and humeral rotation.. Using the ergonomical guide lines can be applied to the design and selection of suitable hand tools for the purpose of reducing injuries and increasing productivity in industry.

REFERENCES

[1.] Thomas, W. McDowell, Bryan M. Wimer, Daniel E. Welcome, Christopher Warren and Ren G. Dong, 2012. Effects of handle size and shape on measured grip strength. International Journal of Industrial Ergonomics. 42: 199-205.

[2.] Raymond W. McGorry, Rammohan V. Maikala, Jia-Hua Lin, Amanda Rivard, 2009. Oxygenation kinetics of forearm muscles as a function of handle diameter during a repetitive power grip force task. International Journal of Industrial Ergonomics., 39: 465-470.

[3.] Mahmut Eksioglua and Kemal Kizilaslan, 2008. Steering-wheel grip force characteristics of drivers as a function of gender, speed, and road condition. International Journal of Industrial Ergonomics, 38: 354-361.

[4.] Zulquernain Mallick, 2008. Optimization of operating parameters for a back- pack type grass trimmer. International Journal of Industrial Ergonomics, 38: 101-110.

[5.] Ming-Lun Lu, Tamara James, Brian Lowea, Marisol Barrero, Yong-Ku Kong, 2008. An investigation of hand forces and postures for using selected mechanical pipettes International Journal of Industrial Ergonomics, 38: 18-29.

[6.] Ignacio Ainsa, David Gonzalez, Miguel Lizaranzu and Carlos Bernad, 2011, Experimental evaluation of uncertainty in hand arm vibration measurements. International Journal of Industrial Ergonomics, 41: 167-179.

[7.] Yong-Ku Kong and Brian D. Lowe, 2005. Evaluation of handle diameters and orientations in a maximum torque task. International Journal of Industrial Ergonomics, 35: 1073-1084.

[8.] Aldien, Y., D. Welcome, S. Rakhejaa, R. Dongb and P.-E. Boileauc, 2005. Contact pressure distribution at hand-handle interface role of hand forces and handle size.. International Journal of Industrial Ergonomics, 35: 267-286.

[9.] Welcomea, D., S. Rakhejab, R. Donga, J.Z. Wua and A.W. Schopper, 2004. An investigation on the relationship between grip, push and contact forces applied to a tool handle. International Journal of Industrial Ergonomics, 34: 507-518.

[10.] Jim R. Potvin, Michael J. Agnew and Cherrie ver woert, 2004. An ergonomic comparison of pneumatic and electrical pistol grip hand tools. International Journal of Industrial Ergonomics, 34: 467-478.

[11.] Chih-Hung Chang and Mao-Jiun J. Wang, 2001. Evaluating the effects of activation mode, torque and horizontal operating distance on hand-arm response while operating pneumatic screw drivers. International Journal of Industrial Ergonomics, 28: 171-179.

[12.] Charlotte hall., 1997. External pressure at the hand during object handling work with tools. International Journal of Industrial Ergonomics, 20: 191-206.

[13.] Jia-Hua Lin and Raymond W. McGorry, 2009. Predicting subjective perceptions of powered tool torque reactions. International Journal of Industrial Ergonomics, 40: 47-55.

[14.] Heecheon You, Anil Kumar, Ronda Young, Prabaharan Veluswamy and Don E. Malzahn, 2005. An ergonomic evaluation of manual Cleco plier designs: Effects of rubber grip, spring recoil, and work surface angle. Applied Ergonomics, 36: 575-583.

[15.] Yuh-Chuan Shih., 2005. Effect of a splint on measures of sustained grip exertion under different forearm and wrist postures. Applied Ergonomics, 36: 293-299.

[16.] Raymond W. McGorry, 2001. A system for the measurement of grip forces and applied moments during hand tool use. Applied Ergonomics, 32: 271-279.

[17.] Jouni Freund, Esa-Pekka Takala and Risto Toivonen, 2000. Effects of two ergonomic aids on the usability of an in-line screw driver. Applied Ergonomics, 31: 371-376.

[18.] John Z. Wu, Ren G. Dong, Daniel, E. Welcome and Xueyan S. Xu, 2010. A method for analyzing vibration power absorption density in human fingertip. International journal of Sound and Vibration, 329: 5600-5614.

[19.] Jennie, H., Dong, Ren G. Dong, Subhash Rakheja, Daniel E. Welcome, Thomas W. McDowell and John Z. Wu, 2008. A method for analyzing absorbed power distribution in the hand and arm substructures when operating vibrating tools. International journal of Sound and Vibration, 311: 1286-1304.

[20.] Yuh-Chuan Shih and Mao-Jiun J. Wang, 1996. Hand/tool interface effects on human torque capacity. International Journal of industrial Ergonomics, 18: 205-213.

[21.] Lawrence, J.H., Schulze, Jerome J. Congleton, Rodger J. Koppa and R. Dale Huchingson, 1995. Effects of pneumatic screwdrivers and workstations on inexperienced and experienced operator performance. International journal of Industrial Ergonomics, 16: 175-189.

[22.] David, R. Burnett and Naira H. Campbell-Kyureghyan, 2010. Quantification of scan-specific ergonomic risk-factors in medical sonography. International journal of Industrial Ergonomics, 40: 306-314.

[23.] Sukwon Kim, Thurmon Lockhart and Chang S. Nam, 2010. Leg strength comparison between younger and middle-age adults. International journal of Industrial Ergonomics, 40: 315-320.

[24.] Rebecca, L., Brookham, Joanna M. Wong and Clark R. Dickerson, 2010. Upper limb posture and submaximal hand tasks influence shoulder muscle activity.. International journal of Industrial Ergonomics, 40: 337-344.

[25.] Grujicic, M., B. Pandurangan, X. Xie, A.K. Gramopadhye, D. Wagner and M. Ozen, 2010. Musculoskeletal computational analysis of the influence of car-seat design/adjustments on long- distance driving fatigue. International journal of Industrial Ergonomics, 40: 345-355. Ergonomics, Universities Gadjah Mada, Yogyakarta.

[26.] Magdalena Jaworek, Tadeusz Marek, Waldemar Karwowski, Chris Andrzejczak and Ash M. Genaidy, 2010. Burnout syndrome as a mediator for the effect of work-related factors on musculoskeletal complaints among hospital nurses. International journal of Industrial Ergonomics, 40: 368- 375.

(1) Sasikumar R and (2) Dr. K. Lenin

(1) Assistant Professor, Department of Mechanical Engineering, VMKV Engineering College, Salem. India

(2) Associate Professor, Jayaram College of Engineering and Technology, Thuraiyur, Tamilnadu, India.

Received 25 April 2016; Accepted 28 May 2016; Available 5 June 2016

Address For Correspondence:

Sasikumar R, Assistant Professor, Department of Mechanical Engineering, VMKV Engineering College, Salem. India E-mail: srisasikumar@gmail.com
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Author:Sasikumar, R.; Lenin, K.
Publication:Advances in Natural and Applied Sciences
Date:May 30, 2016
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