Advances in Mechanical Engineering http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. A Two-DOF Fast Tool Servo for Optical Freeform Surfaces Diamond Turning Wed, 22 Oct 2014 07:38:42 +0000 http://www.hindawi.com/journals/ame/2014/527975/ Fast tool servo (FTS) technology is considered as the most popular technology to fabricate freeform optical lenses and micro- and nano-structured surfaces. Aiming at the disadvantages of existing single DOF FTS systems, this paper described a two-DOF FTS. Cross shape flexure hinges are designed as the guide mechanism, and two voice coil motors (VCMs) are selected to drive the tool motion. The FTS offline performance is tested, and the following error is about less than 0.1 μm; the motion resolution is 0.05 μm. A sinusoidal surface is machined to verify the cutting performance of the novel FTS, and the surface roughness is Ra 27 nm. The test results show that the two-DOF FTS system works well on the fabrication of optical freeform surfaces. Qiang Liu, Xiaoqin Zhou, Pengzi Xu, and Xu Zhang Copyright © 2014 Qiang Liu et al. All rights reserved. A Model to Determine Mesh Characteristics in a Gear Pair with Tooth Profile Error Tue, 21 Oct 2014 08:44:40 +0000 http://www.hindawi.com/journals/ame/2014/751476/ A method to determine the gear mesh stiffness, loaded transmission error, and tooth contact stress is presented with tooth profile error. The single tooth stiffness is calculated by the potential energy method. Contact stress is studied by the classic Hertzian elastic contact theory. Then two cases are presented for validation of the gear mesh stiffness model. It is demonstrated that the gear mesh stiffness model is effective for the gear pair with or without lead crown relief and tip and root relief. Finally, the effects of tooth lead crown relief and applied torque on the gear mesh stiffness are analyzed. The results show that mesh stiffness decreases and loaded transmission error and the maximum tooth contact stress grow with increasing the tooth lead crown relief. And mesh stiffness, loaded transmission error, and the maximum contact stress increase in a certain range as the applied torque increases for the tooth with lead crown relief. Qibin Wang, Peng Hu, Yimin Zhang, Yi Wang, Xu Pang, and Cao Tong Copyright © 2014 Qibin Wang et al. All rights reserved. Thermomechanical Fatigue Life Prediction for a Marine Diesel Engine Piston considering Ring Dynamics Sun, 19 Oct 2014 11:20:37 +0000 http://www.hindawi.com/journals/ame/2014/429637/ A newly designed marine diesel engine piston was modeled using a precise finite element analysis (FEA). The high cycle fatigue (HCF) safety factor prediction procedure designed in this study incorporated lubrication, thermal, and structure analysis. The piston ring dynamics calculation determined the predicted thickness of lubrication oil film. The film thickness influenced the calculated magnitude of the heat transfer coefficient (HTC) used in the thermal loads analysis. Moreover, the gas pressure of ring lands and ring grooves used in mechanical analysis is predicted based on the piston ring dynamics model. Tao He, Xiqun Lu, Dequan Zou, Yibin Guo, Wanyou Li, and Minli Huang Copyright © 2014 Tao He et al. All rights reserved. Experimental Investigation on Characteristics of Flow Instabilities in Centrifugal Pump Impeller under Part-Load Conditions Sun, 19 Oct 2014 08:21:33 +0000 http://www.hindawi.com/journals/ame/2014/604812/ This paper presents an experimental investigation of large-scale flow-field instabilities in a centrifugal pump impeller of low specific speed. Measurements of pump hydraulic performance and flow-field in the impeller passages were made with a hydraulic test rig and a Particle Image Velocimetry (PIV) system separately. Analyses of data and flow structures in the impeller passages were performed. Results showed that an unstable area existed in the range from 0.1 to 0.6 and had a close relationship with vortices in the impeller passages. With decreasing of flow rates, vortices experienced onset to expansion from 0.6 to 0.1 in visualization. was directly influenced by vortices between 0.1 and 0.6; and were significantly influenced by vortices from pressure side to the middle; however the slight impact was observed from the middle to suction side. Thus the experimental results could provide important evidence for the influence of flow instabilities on pump hydraulic performance. Denghao Wu, Yun Ren, Houlin Liu, Jiegang Mu, and Lanfang Jiang Copyright © 2014 Denghao Wu et al. All rights reserved. Improvement of Swirl Chamber Structure of Swirl-Chamber Diesel Engine Based on Flow Field Characteristics Thu, 16 Oct 2014 05:50:28 +0000 http://www.hindawi.com/journals/ame/2014/637813/ In order to improve combustion characteristic of swirl chamber diesel engine, a simulation model about a traditional cylindrical flat-bottom swirl chamber turbulent combustion diesel engine was established within the timeframe of the piston motion from the bottom dead centre (BDC) to the top dead centre (TDC) with the fluent dynamic mesh technique and flow field vector of gas in swirl chamber and cylinder; the pressure variation and temperature variation were obtained and a new type of swirl chamber structure was proposed. The results reveal that the piston will move from BDC; air in the cylinder is compressed into the swirl chamber by the piston to develop a swirl inside the chamber, with the ongoing of compression; the pressure and temperature are also rising gradually. Under this condition, the demand of diesel oil mixing and combusting will be better satisfied. Moreover, the new structure will no longer forma small fluid retention zone at the lower end outside the chamber and will be more beneficial to the mixing of fuel oil and air, which has presented a new idea and theoretical foundation for the design and optimization of swirl chamber structure and is thus of good significance of guiding in this regard. Wenhua Yuan, Yi Ma, Jun Fu, and Wei Chen Copyright © 2014 Wenhua Yuan et al. All rights reserved. Study on Optimizing Operation of Preheating Commissioning for Waxy Crude Oil Pipelines Wed, 15 Oct 2014 14:22:01 +0000 http://www.hindawi.com/journals/ame/2014/894256/ A mathematical model is established for the preheating commissioning process of waxy crude oil pipelines. The governing equations are solved by the finite volume method and the finite difference method. Accordingly, numerical computations are made for the Niger crude oil pipeline and the Daqing-Tieling 3rd pipeline. The computational results agree well with the field test data. On this basis, fluid temperature in the process of the preheating commissioning is studied for single station-to-station pipeline. By comparing different preheating modes, it is found that the effect of forward preheating is the best. Under different preheating commissioning conditions, the optimal combination of outlet temperature and flow rate is given. Jian Zhang, Yi Wang, Xinran Wang, Handu Dong, Jinping Huang, and Bo Yu Copyright © 2014 Jian Zhang et al. All rights reserved. Structure Design and Numerical Simulation of a High Performance Slit in Soft X-Ray Interference Lithography Beamline at SSRF Wed, 15 Oct 2014 06:43:58 +0000 http://www.hindawi.com/journals/ame/2014/981631/ A high precision slit in ultra-high vacuum is designed to develop a good performance soft X-ray interference lithography (XIL) beamline at Shanghai Synchrotron Radiation Facility (SSRF). In order to define the secondary source and enhance the performance of the beamline, many technical difficulties need resolving to design the precision slit. Therefore, to obtain reasonable design scheme, it is necessary to analyze the structural characteristics, the movement situation, the force state, the thermal load state, and the cooling state of the precision slit deeply by numerical simulation. The simulation results and the testing results demonstrate that the mechanical precision of the slit is at a high level and satisfies the requirements of the beamline. Xuepeng Gong, Qipeng Lu, and Zhongqi Peng Copyright © 2014 Xuepeng Gong et al. All rights reserved. Optimization of Process Parameters with Minimum Thrust Force and Torque in Drilling Operation Using Taguchi Method Tue, 14 Oct 2014 10:04:58 +0000 http://www.hindawi.com/journals/ame/2014/925382/ This research outlines the Taguchi optimization methodology, which is applied to optimize cutting parameters in drilling of AISI 1040 steel. The drilling parameters evaluated are cutting speed, feed rate, and helix angle. Series of experiments are conducted to relate the cutting parameters on the thrust force and torque. orthogonal array, signal-to-noise ratio is employed to analyze the influence of these parameters on thrust force and torque during drilling. Analysis of variance (ANOVA) is used to study the effect of process parameters on machining process. The study shows that the Taguchi method is suitable to solve the stated problem with the minimum number of trials. The main objective is to find the important factors and combination of factors that influence the machining process to achieve low thrust force and torque. The analysis of the Taguchi method indicates that the feed rate is the most significant factor affecting the thrust force, while the cutting speed contributes the most to the torque. Suleyman Neseli Copyright © 2014 Suleyman Neseli. All rights reserved. A Numerical Study of the Spring-Back Phenomenon in Bending with a Rebar Bending Machine Mon, 13 Oct 2014 09:04:16 +0000 http://www.hindawi.com/journals/ame/2014/959207/ Recently, the rebar bending methodology started to change from field processing to utilizing rebar bending machines at plant sites prior to transport to the construction locations. Computerized control of rebar plant bending machines provides more accurate and faster bending of rebars than the low quality inefficient field processing alternative. The bending process involves plastic deformation of rebars, where bending stress beyond the yield point of the material is applied. When the bending stress is removed, spring back is caused by the elastic restoring stress. Therefore, an accurate numerical analysis of the spring-back process is required to reduce the bending process errors. The most sensitive factors affecting the spring-back process are the bending radius, the bending angle, the diameter of the rebar, the friction coefficient, and the yielding strength of material. In this paper, we suggest a numerical modeling method using these factors. The finite element modeling of the dynamic mechanical behavior of the material during bending is performed using a commercial dynamic analysis program “DAFUL.” We use the least squares approach to derive the spring-back deflection as a function of the rebar bending parameters. Chang Hwan Choi, Lawrence Kulinsky, Joon Soo Jun, and Jin Ho Kim Copyright © 2014 Chang Hwan Choi et al. All rights reserved. A Model for Analyzing Temperature Profiles in Pipe Walls and Fluids Using Mathematical Experimentation Mon, 22 Sep 2014 08:59:40 +0000 http://www.hindawi.com/journals/ame/2014/490302/ Temperature profiling in both fluid and pipe walls had not been explained theoretically. The equations of energy balance and heat conductivity were queried by introducing known parameters to solve heat transfer using virtual mathematical experimentation. This was achieved by remodeling Poiseuille’s equation. Distribution of temperature profiles between pipe wall, fluid flow, and surrounding air was investigated and validated upon comparison with experimental results. A new dimensionless parameter (unified number (U)) was introduced with the aim of solving known errors of the Reynolds and Nusselts number. Moses E. Emetere Copyright © 2014 Moses E. Emetere. All rights reserved. Supersonic Shear Wave Imaging to Assess Arterial Nonlinear Behavior and Anisotropy: Proof of Principle via Ex Vivo Testing of the Horse Aorta Mon, 22 Sep 2014 05:26:08 +0000 http://www.hindawi.com/journals/ame/2014/272586/ Supersonic shear wave imaging (SSI) is a noninvasive, ultrasound-based technique to quantify the mechanical properties of bulk tissues by measuring the propagation speed of shear waves (SW) induced in the tissue with an ultrasound transducer. The technique has been successfully validated in liver and breast (tumor) diagnostics and is potentially useful for the assessment of the stiffness of arteries. However, SW propagation in arteries is subjected to different wave phenomena potentially affecting the measurement accuracy. Therefore, we assessed SSI in a less complex ex vivo setup, that is, a thick-walled and rectangular slab of an excised equine aorta. Dynamic uniaxial mechanical testing was performed during the SSI measurements, to dispose of a reference material assessment. An ultrasound probe was fixed in an angle position controller with respect to the tissue to investigate the effect of arterial anisotropy on SSI results. Results indicated that SSI was able to pick up stretch-induced stiffening of the aorta. SW velocities were significantly higher along the specimen’s circumferential direction than in the axial direction, consistent with the circumferential orientation of collagen fibers. Hence, we established a first step in studying SW propagation in anisotropic tissues to gain more insight into the feasibility of SSI-based measurements in arteries. D. A. Shcherbakova, C. Papadacci, A. Swillens, A. Caenen, S. De Bock, V. Saey, K. Chiers, M. Tanter, S. E. Greenwald, M. Pernot, and P. Segers Copyright © 2014 D. A. Shcherbakova et al. All rights reserved. Semiactive Self-Tuning Fuzzy Logic Control of Full Vehicle Model with MR Damper Sun, 21 Sep 2014 09:05:03 +0000 http://www.hindawi.com/journals/ame/2014/816813/ Intelligent controllers are studied for vibration reduction of a vehicle consisting in a semiactive suspension system with a magnetorheological (MR) damper. The vehicle is modeled with seven degrees of freedom as a full vehicle model. The semiactive suspension system consists of a linear spring and an MR damper. MR damper is modeled using Bouc-Wen hysteresis phenomenon and applied to a full vehicle model. Fuzzy Logic based controllers are designed to determine the MR damper voltage. Fuzzy Logic and Self-Tuning Fuzzy Logic controllers are applied to the semiactive suspension system. Results of the system are investigated by simulation studies in MATLAB-Simulink environment. The performance of the semiactive suspension system is analyzed with and without control. Simulation results showed that both Fuzzy Logic and Self-Tuning Fuzzy Logic controllers perform better compared to uncontrolled case. Furthermore, Self-Tuning Fuzzy Logic controller displayed a greater improvement in vibration reduction performance compared to Fuzzy Logic controller. Mahmut Paksoy, Rahmi Guclu, and Saban Cetin Copyright © 2014 Mahmut Paksoy et al. All rights reserved. Surface and Wear Analysis of Zinc Phosphate Coated Engine Oil Ring and Cylinder Liner Tested with Commercial Lubricant Thu, 18 Sep 2014 07:18:26 +0000 http://www.hindawi.com/journals/ame/2014/150968/ The objective of this study was to evaluate the tribological performance through investigating protective additive layer and friction coefficient and implementing the quantitative wear measurements on the rubbed surface of the sliding pairs. The specimens of oil ring were rubbed against cast iron engine cylinder liner under boundary lubrication conditions. The ring and liner surfaces were examined by optical, scanning electron microscope and atomic force microscopy. The elemental analysis of surfaces was performed by using energy dispersive X-ray spectroscopy. Surface observations showed that coating was removed from the ring surface. Higher levels of Ca, Zn, P, and S elemental ratios (0.93%, 0.45%, 1.55%, and 1.60% as atomic percent) were detected on the cylinder liner surface. Wear width, length, and depth measurements were performed by optical and atomic force microscopies on the ring and cylinder liner surface. The results showed that wear widths for oil ring were 1.59 μm and 1.65 μm; wear widths for cylinder liner were 3.20 μm and 3.18 μm; wear depths for oil ring were 100 nm; and wear depths for cylinder liner were 482 nm. Wear data were taken mostly from the additive layer points detected by SEM and X-ray measurements. Doğuş Özkan and Hakan Kaleli Copyright © 2014 Doğuş Özkan and Hakan Kaleli. 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 http://www.hindawi.com/journals/ame/2014/793269/ 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 http://www.hindawi.com/journals/ame/2014/130925/ 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 http://www.hindawi.com/journals/ame/2014/282513/ 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 http://www.hindawi.com/journals/ame/2014/812060/ 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 http://www.hindawi.com/journals/ame/2014/269721/ 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 http://www.hindawi.com/journals/ame/2014/616341/ 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 http://www.hindawi.com/journals/ame/2014/832470/ 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 http://www.hindawi.com/journals/ame/2014/705629/ 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 http://www.hindawi.com/journals/ame/2014/601253/ 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 http://www.hindawi.com/journals/ame/2014/301751/ 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 http://www.hindawi.com/journals/ame/2014/528031/ 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 http://www.hindawi.com/journals/ame/2014/870349/ 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 http://www.hindawi.com/journals/ame/2014/878679/ 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 http://www.hindawi.com/journals/ame/2014/637052/ 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 http://www.hindawi.com/journals/ame/2014/407218/ 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 http://www.hindawi.com/journals/ame/2014/204930/ 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 http://www.hindawi.com/journals/ame/2014/521706/ 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.