Advances in Mechanical Engineering The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Analysis of the Influence of Microcellular Injection Molding on the Environmental Impact of an Industrial Component Wed, 17 Sep 2014 05:47:21 +0000 Microcellular injection molding is a process that offers numerous benefits due to the internal structure generated; thus, many applications are currently being developed in different fields, especially home appliances. In spite of the advantages, when changing the manufacturing process from conventional to microcellular injection molding, it is necessary to analyze its new mechanical properties and the environmental impact of the component. This paper presents a deep study of the environmental behavior of a manufactured component by both conventional and microcellular injection molding. Environmental impact will be evaluated performing a life cycle assessment. Functionality of the component will be also evaluated with samples obtained from manufactured components, to make sure that the mechanical requirements are fulfilled when using microcellular injection molding. For this purpose a special device has been developed to measure the flexural modulus. With a 16% weight reduction, the variation of flexural properties in the microcellular injected components is only 6.8%. Although the energy consumption of the microcellular injection process slightly increases, there is an overall reduction of the environmental burden of 14.9% in ReCiPe and 15% in carbon footprint. Therefore, MuCell technology can be considered as a green manufacturing technology for components working mainly under flexural load. Daniel Elduque, Isabel Clavería, Ángel Fernández, Carlos Javierre, Carmelo Pina, and Jorge Santolaria Copyright © 2014 Daniel Elduque et al. All rights reserved. Design and Analysis of a Split Deswirl Vane in a Two-Stage Refrigeration Centrifugal Compressor Sun, 14 Sep 2014 11:30:33 +0000 This study numerically investigated the influence of using the second row of a double-row deswirl vane as the inlet guide vane of the second stage on the performance of the first stage in a two-stage refrigeration centrifugal compressor. The working fluid was R134a, and the turbulence model was the Spalart-Allmaras model. The parameters discussed included the cutting position of the deswirl vane, the staggered angle of two rows of vane, and the rotation angle of the second row. The results showed that the performance of staggered angle 7.5° was better than that of 15° or 22.5°. When the staggered angle was 7.5°, the performance of cutting at 1/3 and 1/2 of the original deswirl vane length was slightly different from that of the original vane but obviously better than that of cutting at 2/3. When the staggered angle was 15°, the cutting position influenced the performance slightly. At a low flow rate prone to surge, when the second row at a staggered angle 7.5° cutting at the half of vane rotated 10°, the efficiency was reduced by only about 0.6%, and 10% of the swirl remained as the preswirl of the second stage, which is generally better than other designs. Jeng-Min Huang and Yue-Hann Tsai Copyright © 2014 Jeng-Min Huang and Yue-Hann Tsai. All rights reserved. Generation Planning Methodology Based on Load Factor for Hydroelectric Power Plants Thu, 11 Sep 2014 08:27:49 +0000 Major parameters affecting the generation capacity of hydroelectric plants are resource regime, reservoir geometry, and water head together with flow rate and efficiency. For the same resource regime and flow rate, water head can be altered depending on generation planning. By means of holding water in the reservoir and consequent increase in head can lead to boost power generation. In this paper, a method to compare two different operational styles has been identified; a plant operating with a low fixed head has been compared to a plant with an increased water head by means of holding water. In order to achieve this objective, an economical model including annual power revenues and net income increase depending on the operational strategy has been developed. Parameters affecting net income gain of the developed model are power generation boost and loss during peak and nonpeak durations, and electricity prices during peak and nonpeak durations. Depending on this model, strategies that would increase the plant revenue streams with increasing reservoir head have been presented in the results section of the paper. Süleyman Hakan Sevilgen and Hasan Hüseyin Erdem Copyright © 2014 Süleyman Hakan Sevilgen and Hasan Hüseyin Erdem. All rights reserved. Adaptive Algorithm for the Quality Control of Braided Sleeving Thu, 11 Sep 2014 07:05:04 +0000 We describe the development and application of a robot vision based adaptive algorithm for the quality control of the braided sleeving of high pressure hydraulic pipes. With our approach, we can successfully overcome the limitations, such as low reliability and repeatability of braided quality, which result from the visual observation of the braided pipe surface. The braids to be analyzed come in different dimensions, colors, and braiding densities with different types of errors to be detected, as presented in this paper. Therefore, our machine vision system, consisting of a mathematical algorithm for the automatic adaptation to different types of braids and dimensions of pipes, enables the accurate quality control of braided pipe sleevings and offers the potential to be used in the production of braiding lines of pipes. The principles of the measuring method and the required equipment are given in the paper, also containing the mathematical adaptive algorithm formulation. The paper describes the experiments conducted to verify the accuracy of the algorithm. The developed machine vision adaptive control system was successfully tested and is ready for the implementation in industrial applications, thus eliminating human subjectivity. Miha Pipan, Andrej Kos, and Niko Herakovic Copyright © 2014 Miha Pipan et al. All rights reserved. Ride Quality Assessment of Bus Suspension System through Modal Frequency Response Approach Thu, 11 Sep 2014 06:32:51 +0000 The ride dynamic characteristics of an urban bus were investigated through simulations with suspension component characteristics and were validated through field measurements. It was performed on highway road at a constant forward speed. A random vibration bus model with two parallel tracks of terrain profile was synthesized with superposition between the left and right sides as well as time delay between front and rear. The bus frequency response model was introduced with embedded modal extraction data to enhance computation efficiency. The simulation results of the bus model were derived in terms of acceleration PSD and frequency-weighted root mean square acceleration along the vertical axes at three locations, namely, driver side, middle, and rear passenger side, to obtain the overall bus ride performance. Another two sets of new leaf spring design were proposed as suspension parameter analysis. The simulation approach provides reasonably good results in evaluating passenger perception on ride and shows that the proposed new spring design can significantly improve the ride quality of the driver and passengers. Y. S. Kong, M. Z. Omar, L. B. Chua, and S. Abdullah Copyright © 2014 Y. S. Kong et al. All rights reserved. An Adaptive Vision-Based Method for Automated Inspection in Manufacturing Thu, 11 Sep 2014 05:50:36 +0000 This study proposes a new adaptive vision-based method combining discrete wavelet transform- (DWT-) based feature extraction and support vector machine (SVM) classification for automated inspection in manufacturing. This method involves transforming input optical images into a gray-level space and adaptively segmenting them by using region growing combined with DWT-based feature extraction based on support vector machines (SVMs). A multiclassifier SVM is first used to solve multicase problems in inspection. The SVM can be used to effectively classify samples based on the segmented images combined with the image features and perform superior multiclass classification. The proposed algorithm can select the most suitable features for the inspection from many features. The method achieves high-performance inspections and produces more favorable results than existing methods do. Tsun-Kuo Lin Copyright © 2014 Tsun-Kuo Lin. All rights reserved. Influence of Compression Ratio on the Performance and Emission Characteristics of Annona Methyl Ester Operated DI Diesel Engine Thu, 11 Sep 2014 00:00:00 +0000 This study aims to find the optimum performance and emission characteristics of single cylinder variable compression ratio (VCR) engine with different blends of Annona methyl ester (AME) as fuel. The performance parameters such as specific fuel consumption (SFC), brake thermal efficiency (BTE), and emission levels of HC, CO, Smoke, and NOx were compared with the diesel fuel. It is found that, at compression ratio of 17 : 1 for A20 blended fuel (20% AME + 80% Diesel) shows better performance and lower emission level which is very close to neat diesel fuel. The engine was operated with different values of compression ratio (15, 16, and 17) to find out best possible combination for operating engine with blends of AME. It is also found that the increase of compression ratio increases the BTE and reduces SFC and has lower emission without any engine in design modifications. Senthil Ramalingam, Paramasivam Chinnaia, and Silambarasan Rajendran Copyright © 2014 Senthil Ramalingam et al. All rights reserved. Vehicle Impact Analysis of Flexible Barriers Supported by Different Shaped Posts in Sloping Ground Thu, 11 Sep 2014 00:00:00 +0000 A roadside guardrail may be constructed near slopes. The desired safety behavior is ensured not only by the guardrail structure itself, but also by the interaction between soil and guardrail post. In the case of horizontal ground, the elastic Winkler spring model and the - curve approach can be used to estimate the soil-post interaction by the finite element method. However, it is difficult to apply those models with the sloping ground cases unless sufficient experimental data are given through the single post impact tests. This paper evaluates, using LS-DYNA software, the vehicle impact performance of flexible barriers made of steel W-Beam guardrails in sloping ground that are also supported over three different types of post configurations. The dynamic performance is tested in terms of maximum deflection, absorbing impact energy, and occupant risk index according to post types. Dong W. Lee, Jae S. Ahn, and Kwang S. Woo Copyright © 2014 Dong W. Lee et al. All rights reserved. Optimal Process Conditions for the Manufacture of Aluminum Alloy Bicycle Pedals Wed, 10 Sep 2014 00:00:00 +0000 Numerous forms and manufacturing methods of bicycle pedals exist in current markets. The purpose of this study was primarily to design an innovative forging die for a bicycle pedal company through a simulative analysis, using commercial finite element package software. A series of simulation analyses adopted workpiece temperature, mold temperature, forging speed, friction factor, and size of the mold as variables to evaluate the methods of lightweight in the bicycle pedal forging press. The study involved modifying professional bicycle pedal sizes. The effective strain, effective stress, and die radius load distribution of the pedals were analyzed under various forging conditions. Aluminum (A6061 and A7075) was used to analyze the simulative data. The optimal control parameters were subsequently obtained using the Taguchi methods and a genetic algorithm. The results of the simulation analyses indicated that the design of an experimental forging die can lower the deformation behavior of a bicycle pedal. Dyi-Cheng Chen, Jheng-Guang Lin, Wen-Hsuan Ku, and Jiun-Ru Shiu Copyright © 2014 Dyi-Cheng Chen et al. All rights reserved. A Comparison of a Standard Genetic Algorithm with a Hybrid Genetic Algorithm Applied to Cell Formation Problem Sun, 07 Sep 2014 11:00:17 +0000 Though there are a number of benefits associated with cellular manufacturing systems, its implementation (identification of part families and corresponding machine groups) for real life problems is still a challenging task. To handle the complexity of optimizing multiple objectives and larger size of the problem, most of the researchers in the past two decades or so have focused on developing genetic algorithm (GA) based techniques. Recently this trend has shifted from standard GA to hybrid GA (HGA) based approaches in the quest for greater effectiveness as far as convergence on to the optimum solution is concerned. In order to prove the point, that HGAs possess better convergence abilities than standard GAs, a methodology, initially based on standard GA and later on hybridized with a local search heuristic (LSH), has been developed during this research. Computational experience shows that HGA maintains its accuracy level with increase in problem size, whereas standard GA looses its effectiveness as the problem size grows. Waqas Javaid, Adnan Tariq, and Iftikhar Hussain Copyright © 2014 Waqas Javaid et al. All rights reserved. Numerical Computation and Optimization of Turbine Blade Film Cooling Thu, 04 Sep 2014 00:00:00 +0000 The effect of film cooling parameters on the cooling effectiveness of an actual turbine blade is studied numerically. Film cooling parameters such as the hole shape, holes distribution, blowing ratio, streamwise angle, and spanwise angle are investigated to select the appropriate cooling parameters. Unstructured finite volume technique is used to solve the steady, three-dimensional, and compressible Navier-Stokes equations. Using one cooling holes array indicates that the average overall film cooling effectiveness is enhanced by decreasing the streamwise angle for high blowing ratio on the suction side of the turbine blade. The film cooling effectiveness is enhanced on the pressure side for a blowing ratio of unity. In addition, the cooling effectiveness increases by increasing the lateral and forward diffusion angles. The computations reveal that the efficiency of cooling is decreased at the leading edge due to the large surface curvature of the blade. The presence of compound shape (spanwise angle) enhanced the film cooling effectiveness on the two sides. Multistagger cooling hole arrays are investigated and the results indicate that five-stagger cooling arrays on the pressure side and three-stagger cooling arrays on the suction side with LFDCA-9.3-14.6 hole shape are enough to have good cooling of the two sides using 2.17% bleed air of the engine. Ahmed M. Elsayed, Farouk M. Owis, and M. Madbouli Abdel Rahman Copyright © 2014 Ahmed M. Elsayed et al. All rights reserved. Improving Vehicle Safety: A New Methodology for Vehicle Steering System Inspection by Means of Forces Measure Wed, 03 Sep 2014 00:00:00 +0000 Some mechanical systems, such as steering, brakes, and suspension, critically affect the safety of the vehicle. These systems are subject to wear through use and time, changing their status throughout the lifetime of a vehicle. It is, therefore, essential to develop adequate components and procedures of inspection that ensure the correct operation of these systems. Moreover, the steering inspection must guarantee certain requirements, such as, being able to test any vehicle steering system and being low priced. In addition, one of the most important requirements for any inspection procedure is to provide the measurements in a short time. This fact conditions the measurement process and sensors to be employed. The current steering system that measures the steering angles is time consuming. The aim of this research is to introduce a steering system inspection based on forces measured by means of a dynamometer plate. The main features of the proposed system ensure minimum testing time, and simple operation and avoid manipulation of the vehicle. In addition, precise and objective limits for acceptance and rejection have been established. Therefore, the proposed procedure meets all the requirements for the periodic motor vehicle inspection (PMVI). D. García-Pozuelo, V. Díaz, and M. J. L. Boada Copyright © 2014 D. García-Pozuelo et al. All rights reserved. Characteristics of Large-Scale Structures in Supersonic Planar Mixing Layer with Finite Thickness Tue, 02 Sep 2014 12:16:12 +0000 Nanoparticle-based planar laser scattering (NPLS) experiments and large eddy simulation (LES) were launched to get the fine structure of the supersonic planar mixing layer with finite thickness in the present study. Different from the turbulent development of supersonic planar mixing layer with thin thickness, the development of supersonic planar mixing layer with finite thickness is rapidly. The large-scale structures of mixing layer that possess the characters of quick movement and slow changes transmit to downriver at invariable speed. The transverse results show that the mixing layer is strip of right and dim and possess 3D characteristics. Meanwhile the vortices roll up from two sides to the center. Results indicate that the higher the pressure of the high speed side is, the thicker the mixing layer is. The development of mixing layer is restrained when the pressure of lower speed side is higher. The momentum thickness goes higher with the increase of the clapboard thickness. Through increasing the temperature to change the compression can affect the development of the vortices. The present study can make a contribution to the mixing enhancement and provide initial data for the later investigations. Hailong Zhang, Jiping Wu, Jian Chen, and Weidong Liu Copyright © 2014 Hailong Zhang et al. All rights reserved. Numerical Study on the Effect of Tube Rows on the Heat Transfer Characteristic of Dimpled Fin Tue, 02 Sep 2014 09:51:10 +0000 The dimpled fin has excellent heat transfer performance and has attracted a lot of attention to apply on the fin and tube heat exchanger. A study presents to investigate the effects of number of tube rows on the air-side heat transfer characteristics of dimpled fin for velocity ranging from 1 to 3 m/s. The and are used to evaluate the heat transfer performance of the heat exchanger. The results show that the dimpled arrangement can change the mainstream direction, increase the disturbance, and enhance the heat transfer. With the increase of the number of tube rows, the average Nusselt number decreases and and increase gradually. Compared with the multipipe tube rows, the performance of two-row tube is better. Xuehong Wu, Lihua Feng, Dandan Liu, Hao Meng, and Yanli Lu Copyright © 2014 Xuehong Wu et al. All rights reserved. Using of Multiwall Carbon Nanotube Based Nanofluid in the Heat Pipe to Get Better Thermal Performance Mon, 01 Sep 2014 12:14:55 +0000 Thermal performance of a cylindrical heat pipe is investigated numerically. Three different types of water based nanofluids, namely, Al2O3 + Water, Diamond + Water, and Multi-Wall Carbon Nano tube (MWCNT) + Water, have been used. The influence of using the simple nanofluids and MWCNT nanofluid on the heat pipe characteristics such as liquid velocity, pressure profile, temperature profile, thermal resistance, and heat transfer coefficient of heat pipe has been studied. A new correlation developed by Bakhshan and Saljooghi (2014) for viscosity of nanofluids has been implemented. The results show, a good agreement with the available analytical and experimental data. Also the results show, that the MWCNT based nanofluid has lower thermal resistance, higher heat transfer coefficient, and lower temperature difference between evaporator and condenser sections, so it has good thermal specifications as a working fluid for use in heat pipes. The prepared code has capability for parametric studies also. Y. Bakhshan, S. Motadayen Aval, F. Kamel, and A. Hajhossini Copyright © 2014 Y. Bakhshan et al. All rights reserved. Sequence Planning and Tool Selection for Bending Processes of 2.5D Sheet Metals Mon, 01 Sep 2014 12:14:11 +0000 Planning of an appropriate bending sequence is one of the most important aspects in the processing of sheet metals as the appropriateness of the plan affects correct selection of bending tools and feasibility of bending processes. This study aims to propose a set of principles to be followed for the planning of bending sequences and selection of bending tools for 2.5D sheet metals. To this end, we first define basic bending patterns by characterizing each pattern with a set of operation rules. The sheet metal is then decomposed into a series of bending patterns that is in turn used in the planning of bending sequences. In order to select the bending tools, we combine the contours of each bending operation, choose appropriate bending punches from the bending-tool database, and then undertake an interference check with the bending contours. Alan C. Lin and Chao-Fan Chen Copyright © 2014 Alan C. Lin and Chao-Fan Chen. All rights reserved. CFD Numerical Simulation of the Complex Turbulent Flow Field in an Axial-Flow Water Pump Mon, 01 Sep 2014 12:04:48 +0000 Further optimal design of an axial-flow water pump calls for a thorough recognition of the characteristics of the complex turbulent flow field in the pump, which is however extremely difficult to be measured using the up-to-date experimental techniques. In this study, a numerical simulation procedure based on computational fluid dynamics (CFD) was elaborated in order to obtain the fully three-dimensional unsteady turbulent flow field in an axial-flow water pump. The shear stress transport (SST) k-ω model was employed in the CFD calculation to study the unsteady internal flow of the axial-flow pump. Upon the numerical simulation results, the characteristics of the velocity field and pressure field inside the impeller region were discussed in detail. The established model procedure in this study may provide guidance to the numerical simulations of turbomachines during the design phase or the investigation of flow and pressure field characteristics and performance. The presented information can be of reference value in further optimal design of the axial-flow pump. Wan-You Li, Xiang-Yuan Zhang, Zhi-Jun Shuai, Chen-Xing Jiang, and Feng-Chen Li Copyright © 2014 Wan-You Li et al. All rights reserved. Safety Control on the Chocking Process of Supercritical Carbon Dioxide Pipeline Mon, 01 Sep 2014 08:47:52 +0000 Transportation safety of supercritical CO2 pipeline is a key aspect of carbon capture and storage (CCS). For reducing the high pressure in supercritical pipeline when accidental cases arise, man-made release will be applied using chocking process. The downstream parameters of chocking process can be predicted based on the adiabatic process assumption. In the critical chocking process, the critical velocity at outlet is sonic. A chocking pipe can be designed for buffering between different chocking orifices according to the length of turbulence area produced by jetting momentum. For the effect of noise hazard produced by large jetting velocity, a muffler can be applied at the outlet of final stage orifice to atmosphere. For the influence of impurities on the chocking process of anthropogenic CO2 pipeline, the presence of SO2 as an impurity is helpful for increasing the downstream temperatures through the chocking device to prevent the frozen hazard, whereas the presence of N2 as an impurity indicates a lower downstream temperature. The higher initial temperature can prevent the dry ice formation at the outlet of vent pipe when the multistage chocking is applied. Qing Zhao, Yuxing Li, and Shunli Li Copyright © 2014 Qing Zhao et al. All rights reserved. Pump and Pumping System Mon, 01 Sep 2014 08:34:19 +0000 Weidong Shi, Wang Zheng-Wei, Li Ren-Nian, Leqin Wang, and Shibo Kuang Copyright © 2014 Weidong Shi et al. All rights reserved. Collaborative Synchronization Digital Control for Double Hydraulic Cylinders Mon, 01 Sep 2014 07:23:59 +0000 By researching the synchronization motion of double hydraulic cylinders controlled by high-speed on-off valve, the paper aims to solve the shortage of current hydraulic synchronization system with low synchronization precision. The flow characteristic of high-speed on-off valve with pulse width-frequency modulation is researched compared with pulse width modulation. The mathematical equations of the double hydraulic cylinders are formulated with bulk-cavity-node method in MATLAB/Simulink. The collaborative synchronization control is analyzed and the compound algorithm of collaborative synchronization control and pulse width-frequency modulation is simulated compared with collaborative synchronization control. The hydraulic loop is set up to verify the simulation result with the proposed control algorithm on the FESTO platform. The research finds that (1) the pulse width-frequency modulation control can be linear to the flow of high-speed on-off valve on the duty bound of 0~100%; (2) the collaborative synchronization control is effective to eliminate the displacement error between the double cylinders which results from the different load environment and other disturbance. Zhi-hao Liu, Qin-he Gao, Chuan-qiang Yu, Xiang-yang Li, Wen-liang Guan, and Gang-feng Deng Copyright © 2014 Zhi-hao Liu et al. All rights reserved. Thermal Performance Analysis and Empirical Correlations for Laminar Forced Convection over 30° V-Baffled Square Channel Mon, 01 Sep 2014 06:19:32 +0000 Thermal performance analysis for laminar forced convection in an isothermal wall square channel with 30° V-baffle is presented numerically. The parameters of the V-baffle, blockage ratio (b/H, BR), pitch ratio (P/H, PR), flow direction (V-Downstream and V-Upstream), and arrangement (in-line and staggered), are studied and compared with the previous works, 20° and 45° V-baffle. The Reynolds number based on the hydraulic diameter of the channel (), Re = 100–2000, is used in range study. The results show that the flow configurations of 30° V-baffle are found similar as 20° and 45° V-baffle. The fully developed periodic flow and heat transfer are created around 7th-8th module, while the periodic flow and heat transfer profiles are found at 2nd module in all cases. Except for the periodic concept, the 30° V-baffle can help to reduce the pressure loss around 2.3 times in comparison with the 45° V-baffle at the maximum value (BR = 0.3, PR = 1, V-Downstream). The optimum thermal enhancement factor for the 30° V-baffle is found around 4.25 at BR = 0.15, PR = 1, and Re = 2000 for V-Downstream case with in-line arrangement. Amnart Boonloi and Withada Jedsadaratanachai Copyright © 2014 Amnart Boonloi and Withada Jedsadaratanachai. All rights reserved. CFD and Experimental Analysis of a Falling Film outside Smooth and Helically Grooved Tubes Sun, 31 Aug 2014 07:21:29 +0000 Simultaneous heat and mass transfer are investigated in a falling film outside grooved and smooth tubes. A numerical analysis of the helically trapezoidal-grooved and reference smooth tube was performed in the computational fluid dynamics program “Ansys Fluent 14.” The three-dimensional model drawings in the , , and coordinates are used, and the effects of the falling film outside the helically grooved tube on the surface temperature and surface heat transfer coefficient are determined. The average surface temperature, heat transfer coefficient, and Nu values are determined experimentally for a constant heat flux. An uncertainty analysis and Nu correlation for the grooved tube are also provided in this study. The Reynolds number varied between 50 and 350 for the falling film and between 1500 and 3500 for air. Using a computational fluid dynamics (CFD) analysis for the reference smooth tube, the experimental results are validated within 2–12% difference. The experimental results are also within 6–13% of the grooved tubes. Cenk Onan, Derya Burcu Ozkan, and Serkan Erdem Copyright © 2014 Cenk Onan et al. All rights reserved. Study on Detection and Localization Algorithm of Traffic Signs from Natural Scenes Sun, 31 Aug 2014 07:15:01 +0000 Automatic detection and location of traffic signs is an important part of intelligent transportation, especially for unmanned vehicle technology research. For the morphological feature of China road traffic signs, we propose a traffic sign detection method based on color segmentation and shape analysis. Firstly, in order to solve the problems of traffic signs color cast, distortion, and cross-color in natural scenes, the images are processed by white balance, Retinex color enhancement, and affine transformation. Then, the type of traffic signs is discriminated and detected, according to the color and shape characteristics of traffic signs. The experimental results show that this method can effectively detect and recognize traffic signs. Xian-Zhong Han, Chen Chen, Ke-Jian Wang, Yingchun Yuan, and Yulong Song Copyright © 2014 Xian-Zhong Han et al. All rights reserved. Defect Characterization Based on Eddy Current Technique: Technical Review Thu, 28 Aug 2014 12:31:27 +0000 Eddy current testing is widely used for nondestructive evaluation of metallic structures in characterizing numerous types of defects occurring in various locations. It offers remarkable advantages over other nondestructive techniques because of its ease of implementation. This paper presents a technical review of Eddy current technique in various scope of defect detection. The first part presents Eddy current evaluation on various defects location and orientation such as steam generator tubes, stress crack corrosion, and fatigue cracks. The next section analyzes the use of pulsed Eddy current and pulsed Eddy current thermography as an alternative method for monitoring the growth of cracks with the aid of computational techniques for postsignal analysis. Ruzlaini Ghoni, Mahmood Dollah, Aizat Sulaiman, and Fadhil Mamat Ibrahim Copyright © 2014 Ruzlaini Ghoni et al. All rights reserved. Formalization of Matrix Theory in HOL4 Thu, 28 Aug 2014 12:12:20 +0000 Matrix theory plays an important role in modeling linear systems in engineering and science. To model and analyze the intricate behavior of complex systems, it is imperative to formalize matrix theory in a metalogic setting. This paper presents the higher-order logic (HOL) formalization of the vector space and matrix theory in the HOL4 theorem proving system. Formalized theories include formal definitions of real vectors and matrices, algebraic properties, and determinants, which are verified in HOL4. Two case studies, modeling and verifying composite two-port networks and state transfer equations, are presented to demonstrate the applicability and effectiveness of our work. Zhiping Shi, Yan Zhang, Zhenke Liu, Xinan Kang, Yong Guan, Jie Zhang, and Xiaoyu Song Copyright © 2014 Zhiping Shi et al. All rights reserved. Shift Performance Test and Analysis of Multipurpose Vehicle Thu, 28 Aug 2014 11:20:32 +0000 This paper presented an analysis of the gear shifting performances of a multipurpose vehicle transmission in driving condition by Ricardo’s Gear Shift Quality Assessment (GSQA) system. The performances of the transmission included the travel and effort of the gear shift lever and synchronizing time. The mathematic models of the transmission including the gear shift mechanism and synchronizer were developed in MATLAB. The model of the gear shift mechanism was developed to analyze the travel map of the gear shift lever and the model of the synchronizer was developed to obtain the force-time curve of the synchronizer during the slipping time. The model of the synchronizer was used to investigate the relationship between the performances of the transmission and the variation of parameters during gear shifting. The mathematic models of the gear shift mechanism and the synchronizer provided a rapid design and verification method for the transmission with ring spring. Can Yang, Lin Hua, Zhou Wang, and Yaohua He Copyright © 2014 Can Yang et al. All rights reserved. Research on the Vibration Characteristics of the New Type of Passive Super Static Vibratory Platform Based on the Multiobjective Parameter Optimization Thu, 28 Aug 2014 11:10:55 +0000 In order to reduce impact on payload due to vibration, the new type of passive super static vibratory platform and its dynamic mathematical model were established. In order to obtain the best performance of this platform, the method of multiobjective parameter optimization was applied to decide the parameters such as stiffness coefficient and damping coefficient. Then studying the dynamics inherent characteristic of the platform, the result shows the new type of passive super static vibratory platform has relatively low natural frequency and can effectively reduce the vibration of the high frequency range that means this new type of passive super static vibratory platform was suitable for the satellite payload work environment. Based on the simulation, the experimental platform was manufactured and tested on the platform with random forced vibration; the result shows the new type of passive super static vibratory platform has an obvious vibration damping effect. Jiaqiang E, Cheng Qian, Teng Liu, and Guanlin Liu Copyright © 2014 Jiaqiang E et al. All rights reserved. Responses of a Highly Accelerated Life Test System to Impacts from Different Designs of Hammers Thu, 28 Aug 2014 09:44:51 +0000 The response of a table to the impact of its driving hammer in the highly accelerated life test (HALT) system depends on, among other things, the location of the hammer, the presence of multiple hammers, and the angle at which the hammer is mounted to the table. The present study investigated the response of a table to a variety of impacts from different combinations of hammers. It began with a theoretical analysis of the forces of impact exerted by hammers which led to the calculation of the corresponding displacement. These theoretical calculations revealed the mechanics of the HALT system to help explain the working principles behind this complex system. Then a simulation model was built to check the accuracy of the theoretical results. Finally, the accelerations of a table in a real HALT system were measured. These data showed good agreement with the experimental results and computer simulation. The responses of HALT systems have not been investigated thoroughly to date. The current study can help equipment designers and end users better understand the working principles of this kind of systems. It can be considered a breakthrough in terms of improving the performance of reliability testing with this kind of system. Yeong-Shu Chen and Le Hong Chuong Copyright © 2014 Yeong-Shu Chen and Le Hong Chuong. All rights reserved. Numerical Study of Natural Supercavitation Influenced by Rheological Properties of Turbulent Drag-Reducing Additives Thu, 28 Aug 2014 06:27:54 +0000 Natural supercavitations in water and turbulent drag-reducing solution were numerically simulated using unsteady Reynolds averaged Navier-Stokes (RANS) scheme with mixture-multiphase model. The Cross viscosity equation was adopted to represent the fluid property of aqueous solution of drag-reducing additives. The characteristics of natural supercavity configuration and overall resistance of the navigating body were presented, respectively. The numerical simulation results indicated that, at the same cavitation number, the length and diameter of supercavity in drag-reducing solution are larger than those in water, and the drag coefficient of navigating body in solution is smaller than that in water; the surface tension plays an important role in incepting and maintaining the cavity. Turbulent drag-reducing additives have the potential in enhancement of supercavitation, drag reduction, and decrease of turbulent vortex structures. Numerical simulation results are consistent with the available experimental data. Chen-Xing Jiang and Feng-Chen Li Copyright © 2014 Chen-Xing Jiang and Feng-Chen Li. All rights reserved. Comparisons of Hydraulic Performance in Permanent Maglev Pump for Water-Jet Propulsion Thu, 28 Aug 2014 05:56:25 +0000 The operation of water-jet propulsion can generate nonuniform inflow that may be detrimental to the performance of the water-jets. To reduce disadvantages of the nonuniform inflow, a rim-driven water-jet propulsion was designed depending on the technology of passive magnetic levitation. Insufficient understanding of large performance deviations between the normal water-jets (shaft) and permanent maglev water-jets (shaftless) is a major problem in this paper. CFD was directly adopted in the feasibility and superiority of permanent maglev water-jets. Comparison and discussion of the hydraulic performance were carried out. The shaftless duct firstly has a drop in hydraulic losses (), since it effectively avoids the formation and evolution of the instability secondary vortex by the normalized helicity analysis. Then, the shaftless intake duct improves the inflow field of the water-jet pump, with consequencing the drop in the backflow and blocking on the blade shroud. So that the shaftless water-jet pump delivers higher flow rate and head to the propulsion than the shaft. Eventually, not only can the shaftless model increase the thrust and efficiency, but it has the ability to extend the working range and broaden the high efficiency region as well. Puyu Cao, Yang Wang, K. X. Qian, and Guidong Li Copyright © 2014 Puyu Cao et al. All rights reserved.