bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis and Compensation for Gear Accuracy with Setting Error in Form Grinding
Authors: Fang Chenggang , Gong Jianming , Guo Erkuo , Zhang Hu , Huang Xiaodiao
Published: March 2015

In the process of form grinding, gear setting error was the main factor that influenced the form grinding accuracy; we proposed an effective method to improve form grinding accuracy that corrected the error by controlling the machine operations. Based on establishing the geometry model of form grinding and representing the gear setting errors as homogeneous coordinate, tooth mathematic model was obtained and simplified under the gear setting error. Then, according to the gear standard of ISO1328-1: 1997 and the ANSI/AGMA 2015-1-A01: 2002, the relationship was investigated by changing the gear setting errors with respect to tooth profile deviation, helix deviation, and cumulative pitch deviation, respectively, under the condition of gear eccentricity error, gear inclination error, and gear resultant error. An error compensation method was proposed based on solving sensitivity coefficient matrix of setting error in a five-axis CNC form grinding machine; simulation and experimental results demonstrated that the method can effectively correct the gear setting error, as well as further improving the forming grinding accuracy.
Research of Automatic Progress Report Generation for Railway Construction Projects in China
Authors: Li Qing , Liu Rengkui , Sun Quanxin , Wang Futian
Published: March 2015

The rapid construction of railways in China has posed tremendous challenges for managing railway construction projects, especially their progress. Frequently changed schedule, complicated contents, and error-prone data have practically hampered the efforts to automatically generate progress reports on railway construction projects within the country. In this paper, we set out to explore the linkages among current data from Chinese railway construction units on inspection lots, construction drawings, and construction schedules, which are used to establish an engineering quantity computation model and automatic project progress report model. An automatic progress report generation system for railway construction projects was developed to generate a wide range of standard progress reports. Practical applications showed that the proposed system offers an alternative to hardware-based methods of progress report generation and can significantly improve the accuracy of data and the quality of management regarding project progress.
Fatigue Damage for Sweep-Sine and Random Accelerated Vibration Testing
Authors: Kos Vanja Pahor , Slavič Janko , Boltežar Miha
Published: March 2015

The vibration testing of components in the automotive industry requires long testing times and the use of expensive facilities. To shorten these testing times an accelerated vibration-testing approach is usually applied. This research tries to shorten these testing times by considering the parameters that define vibration-testing techniques. With special attention to the excitation types sweep-sine and random, a damage-based approach is applied. The phenomenon of fatigue damage is closely observed from the frequency-domain point of view but also by considering the relationship between the time and the frequency domains. The Palmgren-Miner cumulative rule is applied to calculate the fatigue life. Two case studies of measured responses are used to compare the times to failure. The results show that proposed predictions can be used to compare different testing techniques, but they are not so accurate when predicting the actual times to failure.
An Effective Computational Approach for the Numerical Simulation of Elasto-/Viscoplastic Solid Materials
Authors: De Angelis Fabio
Published: March 2015

The effects of different loading programs on the elasto-/viscoplastic behavior of rate-sensitive materials are analyzed with specific numerical examples. An appropriate solution scheme and a consistent tangent operator are applied which are capable of being adopted for general computational procedures. Numerical computations and results are reported which illustrate the rate-dependence of the elasto-/viscoplastic constitutive model in use. In the numerical analysis the loading is applied by increasing the pressure and accordingly a nondimensional loading program parameter is introduced. In the numerical results the significance of the loading program is thus emphasized with reference to the nonlinear response of the elasto-/viscoplastic material behavior of solids.
Unified Singularity Modeling and Reconfiguration of 3rTPS Metamorphic Parallel Mechanisms with Parallel Constraint Screws
Authors: Zhuang Yufeng , Gan Dongming
Published: March 2015

This paper presents a unified singularity modeling and reconfiguration analysis of variable topologies of a class of metamorphic parallel mechanisms with parallel constraint screws. The new parallel mechanisms consist of three reconfigurable rT PS limbs that have two working phases stemming from the reconfigurable Hooke (rT) joint. While one phase has full mobility, the other supplies a constraint force to the platform. Based on these, the platform constraint screw systems show that the new metamorphic parallel mechanisms have four topologies by altering the limb phases with mobility change among 1R2T (one rotation with two translations), 2R2T, and 3R2T and mobility 6. Geometric conditions of the mechanism design are investigated with some special topologies illustrated considering the limb arrangement. Following this and the actuation scheme analysis, a unified Jacobian matrix is formed using screw theory to include the change between geometric constraints and actuation constraints in the topology reconfiguration. Various singular configurations are identified by analyzing screw dependency in the Jacobian matrix. The work in this paper provides basis for singularity-free workspace analysis and optimal design of the class of metamorphic parallel mechanisms with parallel constraint screws which shows simple geometric constraints with potential simple kinematics and dynamics properties.
Noncooperative Dynamic Game Model between Drivers and Crossing Pedestrians
Authors: Cheng Guozhu , Liu Botong , Wu Lixin , Fang Qingheng , Yu Ke
Published: March 2015

In China, unsignalized crosswalks lead to the increasing ofconflicts between vehicles and crossing pedestrians. In this paper, the relationships of risks perceived by drivers, crossing pedestrians, and vehicle speed were revealed through a decision-making risk experiment. The model of collision risk probability was established by using probability theory. Then the strategy spaces, the payoff function, and payoff matrix were given. The model of dynamic noncooperative game between the drivers and crossing pedestrians was established. In addition, the equilibrium solutions of the model were analyzed as well. The results of analysis shows that the crossing state is the best decision for pedestrians and drivers should keep uniform speed or accelerate when vehicle speed is low. At medium speed, there is no clear difference between waiting and crossing state for pedestrians. Actually, the crossing state is better than waiting state. For drivers, there is no evident difference among acceleration, deceleration, and keeping uniform speed of vehicles, but the better choice is keeping uniform speed of vehicles. At high speed, pedestrians should not cross because of there are high risks. Therefore, the best solution is that the drivers keep uniform speed of vehicles.
Application of Gene Structure and Mitosis Concepts to the Study and Design of Folding Mechanisms
Authors: Yang Fei , Deng Zongquan , Tao Jianguo , Jiang Shengyuan , Yue Honghao
Published: March 2015

The goal of this study was to develop a novel approach to the study and design of metamorphic mechanisms, based on a consideration of gene structure, mitosis, and cell fusion. In this study, we treat kinematic pairs as basic connection units that function similarly to the base pairs in DNA molecules and present expressions for the configuration of each kinematic pair in a mechanism. We also develop some methods to describe changes in the number of links, number of kinematic pairs, and pair features (type and configuration) during the folding process. Finally, we propose a method based on mitosis and cell fusion for studying the folding process and innovating mechanism design. In this method, a mechanism is first decomposed into some basic kinematic chains, and then these chains (with folding function) are fused into one complete mechanism. Two examples are presented to demonstrate the use of the methods proposed in this study. Overall, we found that, for innovation in mechanism design, it is useful to consider gene connection and mutation as well as mitosis and cell fusion.
CFD Study of Drag and Lift of Sepak Takraw Ball at Different Face Orientations
Authors: Mubin Abdul Syakir Abdul , Ahmad Norhafizan , Mamat Azuddin , Taha Zahari , Hasanuddin Iskandar
Published: March 2015

There have been a significant number of researches on computational fluid dynamic (CFD) analysis of balls used in sports such as golf balls, tennis balls, and soccer balls. Sepak takraw is a high speed court game predominantly played in Southeast Asia using mainly the legs and head. The sepak takraw ball is unique because it is not enclosed and made of woven plastic. Hence a study of its aerodynamicswould give insight into its behaviour under different conditions of play. In this study the dynamics of the fluid around a static sepak takraw ball was investigated at different wind speeds for three different orientations using CFD. It was found that although the drag did not differ very much, increasing the wind velocity causes an increase in drag. The lift coefficientvaries as the velocity increases and does not show a regular pattern. The drag and lift coefficients are influenced by the orientation of the sepak takraw ball.
Investigation and Optimization of Disk-Laser Welding of 1 mm Thick Ti-6Al-4V Titanium Alloy Sheets
Authors: Caiazzo Fabrizia , Alfieri Vittorio , Fierro Ilaria , Sergi Vincenzo
Published: March 2015

Ti-6Al-4V joints are employed in nuclear engineering, civil industry, military, and space vehicles. Laser beam welding has been proven to be promising, thanks to increased penetration depth and reduction of possible defects of the welding bead; moreover, a smaller grain size in the fusion zone is better in comparison to either TIG or plasma arc welding, thus providing an increase in tensile strength of any welded structures. In this frame, the regression models for a number of crucial responses are discussed in this paper. The study has been conducted on 1 mm thick Ti-6Al-4V plates in square butt welding configuration; a disk-laser source has been used. A three-level Box-Behnken experimental design is considered. An optimum condition is then suggested via numerical optimization with the response surface method using desirability functions with proper weights and importance of constraints. Eventually, Vickers microhardness testing has been conducted to discuss structural changes in fusion and heat affected zone due to welding thermal cycles.
Study on Tension-Compression Fatigue Properties of Hard Machined Components
Authors: Chen Tao , Liu Xianli , Li Suyan , Li Kai
Published: March 2015

Hard turning and fatigue tests are conducted to study the influence of cutting process on the fatigue properties of hard machined components in this work. The specimens are machined under various cutting speeds and tool wear condition. Tension-compression fatigue tests of the specimens are performed. The typical fatigue fracture patterns are observed and discussed. The fatigue life of the specimens is recorded and compared. The mechanism of the influence of white layer on fatigue properties is proposed, and the effects of white layer on the fatigue life are obtained. The changing process of tensile and compressive residual stresses is discussed. The effects of surface residual stress and maximum residual stress on the fatigue life are clarified.
Dempster-Shafer Multifeature Fusion for Pedestrian Detection
Authors: Cui Hua , Peng Lingling , Song Huansheng , Wang Guofeng , Li Jiancheng , Guo Lu , Yuan Chao
Published: March 2015

Pedestrian detection is of great importance for ensuring traffic safety. In recent years, many works employing image-based shape features to recognize pedestrians have been reported. However, previous pedestrian detectors were in many cases not sufficient to achieve satisfactory results under complex weather conditions and complex scenarios. As a solution this paper exploits two video-based motion feature descriptors and applies such motion features to the detection task in addition to four classical shape features with the aim of significantly improving the detection performance. Our motion features are defined as the trajectory smoothness degree and motion vector field, which are derived from our proposed point tracking strategy beyond tough target segmentation. And then the appealing Dempster-Shafer theory of evidence (D-S theory) is applied to fuse these features, due to the fact that D-S theory is better than the classical Bayesian approach in handling the information with lack of prior probabilities. The proposed automatic pedestrian detection algorithm is evaluated on real data and in real traffic scenes under various weather conditions. Theoretical analysis and experiment results consistently show that the proposed method outperforms SVM-based multifeature fusion approach for pedestrian detection in terms of recognition ability and robustness in various real traffic scenes.
Performance Analysis of Functionally Graded Coatings in Contact with Cylindrical Rollers
Authors: Jahedi Reza , Adibnazari Saeed , Farrahi Gholam Hossein
Published: March 2015

This work presents finite element analysis (FEA) and results for rolling contact of a cylindrical roller on an elastic substrate coated by functionally graded material (FGM). The rolling process and the graded coating material property and layers arrangement are modeled using finite element codes which lead to a new methodology. This novel methodology provides a trend in determining surface contact stresses, deformations, contact zones, and energy dissipation through the contact area. Effects of stiffness ratio, friction, and exponentially variation of material property on the contact stresses and deformations are studied. Some of the results are verified with analytical solutions. The study results may be beneficial in graded coated cylindrical components analysis against rolling contact failure and wear.
Numerical Investigation of Wall Cooling and Suction Effects on Supersonic Flat-Plate Boundary Layer Transition Using Large Eddy Simulation
Authors: Wang Suozhu , Lei Juanmian , Zhen Huaping , Lee Chunhian
Published: March 2015

Reducing friction resistance and aerodynamic heating has important engineering significance to improve the performances of super/hypersonic aircraft, so the purpose of transition control and turbulent drag reduction becomes one of the cutting edges in turbulence research. In order to investigate the influences of wall cooling and suction on the transition process and fully developed turbulence, the large eddy simulation of spatially evolving supersonic boundary layer transition over a flat-plate with freestream Mach number 4.5 at different wall temperature and suction intensity is performed in the present work. It is found that the wall cooling and suction are capable of changing the mean velocity profile within the boundary layer and improving the stability of the flow field, thus delaying the onset of the spatial transition process. The transition control will become more effective as the wall temperature decreases, while there is an optimal wall suction intensity under the given conditions. Moreover, the development of large-scale coherent structures can be suppressed effectively via wall cooling, but wall suction has no influence.
Evaluation Index Development for Intelligent Transportation System in Smart Community Based on Big Data
Authors: Li Ruimin , Kido Ai , Wang Shi
Published: March 2015

A scientific evaluation index system for intelligent transportation system (ITS) can play an important role in guiding the development of ITS for decision makers in smart communities. This study aims to develop a set of performance indicators for the effective evaluation of the transportation system in a smart community in China. The main goals of the developed evaluation index are determined after a careful review of the various index systems implemented by various agencies worldwide. A set of indicators divided into the following six categories are then presented: transport structure, traffic information service, traffic efficiency, traffic safety, energy and pollution reduction, and social inclusion. To further discuss the practical application of the index system, a number of indicators are defined in detail and applied in arterial and public transportation efficiency evaluations based on the available dataset. Results from the index calculation show that the index proposed in this study can be adopted in evaluating the transportation system performance in smart communities based on big data.
Exploring Driver Injury Severity at Intersection: An Ordered Probit Analysis
Authors: Zhang Yaping , Fu Chuanyun , Cheng Shaowu
Published: March 2015

It is well known that intersections are the most hazardous locations; however, only little is known about driver injury severity in intersection crashes. Hence, the main goal of this study was to further examine the different factors contributing to driver injury severity involved in fatal crashes at intersections. Data used for the present analysis was from the US DOT-Fatality Analysis Reporting System (FARS) crash database from the year 2011. An ordered probit model was employed to fit the fatal crash data and analyze the factors impacting each injury severity level. The analysis results displayed that driver injury severity is significantly affected by many factors. They include driver age and gender, driver ethnicity, vehicle type and age (years of use), crash type, driving drunk, speeding, violating stop sign, cognitively distracted driving, and seat belt usage. These findings from the current study are beneficial to form a solid basis for adopting corresponding measures to effectively drop injury severity suffering from intersection crash. More insights into the effects of risk factors on driver injury severity could be acquired using more advanced statistical models.
Fabrication of Microglass Nozzle for Microdroplet Jetting
Authors: Xie Dan , Chang Xuefeng , Shu Xiayun , Xiao Junfeng , Zhang Honghai
Published: March 2015

An ejection aperture nozzle is the essential part for all microdrop generation techniques. The diameter size, the flow channel geometry, and fluid impedance are the key factors affecting the ejection capacity. A novel low-cost fabrication method of microglass nozzle involving four steps is developed in this work. In the first heating step, the glass pipette is melted and pulled. Then, the second heating step is to determine the tip cone angle and modify the flow channel geometry. The desired included angle is usually of 30~45 degrees. Fine grind can determine the exact diameter of the hole. Postheating step is the final process and it can reduce the sharpness of the edges of the hole. Micronozzles with hole diameters varying from 30 to 100 µm are fabricated by the homemade inexpensive and easy-to-operate setup. Hydrophobic treating method of microglass nozzle to ensure stable and accurate injection is also introduced in this work. According to the jetting results of aqueous solution, UV curing adhesive, and solder, the fabricated microglass nozzle can satisfy the need of microdroplet jetting of multimaterials.
Integrated Measurement System of Performance Parameters of Piezoelectric Ceramic Material
Authors: Lu Qian , Ge Youhua , Chen Xifu
Published: March 2015

The traditional measurement system of piezoelectric ceramic material could only measure a few electrical parameters with low accuracy, while some other important parameters could not be measured. The plane vibration of the piezoelectric vibrator was taken as an object, and the measurement principles of all performance parameters were also analyzed in detail. The hardware and the software of the integrated measurement system were both pointed out, so that the integrated measurement system could measure most of all performance parameters, and other parameters could be obtained by calculation. The experiment results show that all parameters are measured or calculated with high accuracy, and all error rates of all parameters are below 3%. The integrated measurement system simplifies the measurement methods and improves the measurement efficiency, and it would be of great significance to evaluate the performance of the piezoelectric ceramic material.
Mean Velocity Prediction Information Feedback Strategy in Two-Route Systems under ATIS
Authors: Wang Jianqiang , Liu Yingdong
Published: March 2015

Feedback contents of previous information feedback strategies in advanced traveler information systems are almost real-time traffic information. Compared with real-time information, prediction traffic information obtained by a reliable and effective prediction algorithm has many undisputable advantages. In prediction information environment, a traveler is prone to making a more rational route-choice. For these considerations, a mean velocity prediction information feedback strategy (MVPFS) is presented. The approach adopts the autoregressive-integrated moving average model (ARIMA) to forecast short-term traffic flow. Furthermore, prediction results of mean velocity are taken as feedback contents and displayed on a variable message sign to guide travelers' route-choice. Meanwhile, discrete choice model (Logit model) is selected to imitate more appropriately travelers' route-choice behavior. In order to investigate the performance of MVPFS, a cellular automaton model with ARIMA is adopted to simulate a two-route scenario. The simulation shows that such innovative prediction feedback strategy is feasible and efficient. Even more importantly, this study demonstrates the excellence of prediction feedback ideology.
Performance Assessment in a Heat Exchanger Tube with Opposite/Parallel Wing Twisted Tapes
Authors: Eiamsa-ard S. , Pimsarn M. , Thianpong C.
Published: March 2015

The thermohydraulic performance in a tube containing a modified twisted tape with alternate-axes and wing arrangements is reported. This work aims to investigate the effects of wing arrangements (opposite (O) and parallel (P) wings) at different wing shapes (triangle (Tri), rectangular (Rec), and trapezoidal (Tra) wings) and on the thermohydraulic performance characteristics. The obtained results show that wing twisted tapes with all wing shape arrangements (O-Tri/O-Rec/O-Tra/P-Tri/P-Rec/P-Tra) give superior thermohydraulic performance and heat transfer rate to the typical twisted tape. In addition, the tapes with opposite wing arrangement of O-Tra, O-Rec, and O-Tri give superior thermohydraulic performances to those with parallel wing arrangement of P-Tra, P-Rec, and P-Tri around 2.7%, 3.5%, and 3.2%, respectively.
Understanding of the Interaction between Clearance Leakage Flow and Main Passage Flow in a VGT Turbine
Authors: Zhao Ben , Yang Ce , Hu Liangjun , Sun Harold , Yi James , Eric Curtis , Shi Xin , Engeda Abraham
Published: March 2015

The clearance flow between the nozzle and endwall in a variable geometry turbine (VGT) has been numerically investigated to understand the clearance effect on the VGT performance and internal flow. It was found that the flow rate through turbine increases but the turbine efficiency decreases with height of clearance. Detailed flow field analyses indicated that most of the efficiency loss resulting from the leakage flow occurs at the upstream of the rotor area, that is, in the nozzle endwall clearance and between the nozzle vanes. There are two main mechanisms associated with this efficiency loss. One is due to the formation of the local vortex flow structure between the clearance flow and the main flow. The other is due to the impact of the clearance flow on the main flow after the nozzle throat. This impact reduces the span of shockwave with increased shockwave magnitude by changing the trajectory of the main flow.
Vibration Analysis of Randomly Oriented Carbon Nanotube Based on FGM Beam Using Timoshenko Theory
Authors: Rashidifar Mohammad Amin , Ahmadi Darvish
Published: March 2015

The carbon nanotube (CNT) reinforced functionally graded materials (FGM) are expected to be the new generation materials having wide range of unexplored potential applications in various technological areas such as aerospace and structural and chemical industry. The present work deals with the finite element modeling and free vibration analysis of CNT based functionally graded beam using three-dimensional Timoshenko beam theory. It has been assumed that the material properties of CNT based FG beam vary only along the thickness and these properties are evaluated by rule of mixture. The extended Hamilton principle has been applied to find out the governing equations of CNT based FG beam. Finite element method is used to solve governing equation with the exact shape functions. Initial analysis deals with CNTs assumed to be oriented along the length direction only. But practically it is not possible. So, further work deals with the free vibration analysis of functionally graded nanocomposite beams reinforced by randomly oriented straight single walled carbon nanotubes (SWCNTs). The Eshelby-Mori-Tanaka approach based on an equivalent fiber is used to investigate the material properties of the beam. Results are presented in tabular and graphical forms to show the effects of carbon nanotube orientations, slenderness ratios, and boundary conditions on the dynamic behavior of the beam.
Numerical Analysis and Optimization on Flow Distribution and Heat Transfer of a U-Type Parallel Channel Heat Sink
Authors: Hao Xiaohong , Wu Zongxiang , Chen Xuefeng , Xie Gongnan
Published: March 2015

The issue of uniform flow distribution has recently received growing attention for heat sinks design. In order to improve the flow uniformity and heat transfer capacity of a U-type heat sink, a multiobjective optimization design is presented based on the orthogonal experiment design method. Therefore, a computational fluid dynamics model is established, and then the flow fields and temperature fields are investigated. The results show that the distribution of the fluid into each parallel channel not only is a function of the flow conditions in the header but also is affected by the geometric size of the header and the parallel channels and that the optimum U-type heat sink based on orthogonal experiment design method can give uniform flow distribution.
Lightweight Medium-Sized Parts Made of Foamed HDPE Processed via Extrusion Blow Moulding: Analysis of Parison Formation
Authors: Peinado Victor , García Lidia , Fernández Ángel , Castell Pere
Published: March 2015

The manufacturing of medium-sized hollow parts using a foamed high density polyethylene was studied using a conventional accumulator blow extrusion machine and a systematic capture of pictures during the parison formation. To fully monitor the parison formation, several experiments were carried out varying the chemical foaming agent content from 0 wt.% to 2 wt.% and increasing the push extrusion speed. Results pointed out greater wall thickness, diameter, and length of parisons with higher weight percentage of blowing agent and extrusion speed. A full experimental characterisation of parison dimensions was essential to assure a proper prediction of the blowing step. Information was used as input for modelling and simulations of the blowing phase of an industrial container. To validate the proposed methodology, a blow moulding process of a generic container was simulated using Ansys Polyflow v13 software and its finite element analysis which provided an accurate approximation of the wall thickness expected. Further real tests on the simulated container also demonstrated that, in those parisons with a 1 wt.% CFA concentration and higher blowing pressure, there was remarkable improvement on their packaging properties such as decreasing of the total weight of the container and an enhancement of its surface quality.
Heat Transfer Characteristics of Multinozzle Air Impingement Jet during Die Steel Plate Cooling Progress
Authors: Zhu Dong-mei , Wang Yan-tao , Zhu Jian-hua
Published: March 2015

Aiming at the new die steel quenching equipment, using Fluent software, the effects of the nozzle spacing, height, injection pressure, and comprehensive factors on the heat transfer characteristics are studied. The results show that when the nozzle spacing and injection pressure are given, the heat transfer coefficient increases first and then decreases with the injection height increase, and the cooling uniformity is better; when the injection pressure is given, the injection height increases with the nozzle spacing increase under the maximum heat exchanger capability; when the nozzle spacing is given, the injection height increases with the injection pressure under the maximum heat exchanger capability; for the nozzle arrangement in the paper, there is a relationship between the injection height and nozzle spacing when the heat transfer is uniform, H ≈ 8 S. The results have important reference value for optimization design of the equipment and actual production process.
Numerical Effectiveness of the Simulation of an Automotive Body Part Stamping
Authors: Stadnicki Jacek , Wróbel Ireneusz
Published: March 2015

The simulation of advanced high-strength steel sheet (AHSS) stamping processes by means of dedicated computer-aided engineering (CAE) software requires the use of appropriate material models, the use of complex FEM models, and the use of advanced methods for solving nonlinear problems of their analysis. In practice, the engineering design of automotive body parts often leads to the formulation of problems, the solution of which requires ample computer resources and is very time-consuming. The paper describes a methodology to simulate stamping on the example of a car body part, with special attention being paid to the numerical efficiency of the FEM model and methods of solving it. The simulations of stamping of a sample stamped part—the automotive body part—in DynaForm and AutoForm programs are compared, focusing on the numerical effectiveness and consistency of the simulation results with the reality.
The Dynamic Similitude Design of a Thin-Wall Cylindrical Shell with Sealing Teeth and Its Geometrically Distorted Model
Authors: Luo Zhong , Zhu Yunpeng , Han Qingkai , Wang Deyou
Published: March 2015

This study investigates a method of designing a simplified cylindrical shell model. This model accurately predicts the dynamic characteristics of a prototype cylindrical shell with sealing teeth accurately. The significance of this study is that it provides an acceptable process which guides the design of test models. Firstly, an equivalent cylindrical shell with rectangular rings is designed by combining the energy equation and numerical analysis. Then the transfer matrixes of the stiffened cylindrical shell and the cylindrical shell are employed to calculate the equivalent thickness of the simplified cylindrical shell commonly used in model tests. Further, the equivalent thicknesses are normalized by introducing an average equivalent thickness. The distorted scaling laws and size applicable intervals are investigated to reduce the errors caused by the normalization. Finally, a 42CrMo cylindrical shell with sealing teeth is used as a prototype and a number 45 steel scaled-down cylindrical shell is used as a distorted test model. The accuracy of the prediction is verified by using experimental data, and the results indicate that the distorted model can predict the characteristics of the stiffened cylindrical shell prototype with good accuracy.
Numerical Study and Structural Optimization of a Top Combustion Hot Blast Stove
Authors: Qi Fengsheng , Liu Zhongqiu , Yao Chaoyi , Li Baokuan
Published: March 2015

The hot blast stove is one of the most important equipment devices in the blast furnace iron making process. The temperature and duration of hot air are the crucial parameters to assess the performance of the hot blast stove. In order to sustain the desired high temperature air, it requires rapid completed combustion reaction, stable flue gas flow structure, and uniform temperature distribution throughout the regenerator. In the present work, a 3D numerical model with all essential turbulence, heat transfer, and combustion considerations has been developed to assess the performance of a typical hot air stove. The flow field of the whole domain and temperature distribution within the regenerator were simulated using the model. The predicted results show that the velocity at each nozzle varies substantially due to the uneven pressure distribution in cavity of the traditional hot blast stove, generating the eccentric vortex that leads to nonuniform temperature distribution in the regenerator. In order to solve this problem, a new structure design of top combustion regenerative hot blast stove is proposed. Numerical simulations were then carried out to compare based on the performance of the new hot blast stove design against the traditional hot blast stove.
Output Torque for Electromagnetic Harmonic Drive
Authors: Xu Lizhong , Liang Yongli
Published: March 2015

The operation principle of an electromagnetic harmonic drive is analyzed and its speed ratio equation is given. The equations of the displacements of the flexible ring under magnetic forces and the equations of the output torque between the flexible ring and rigid one are deduced. Using these equations, the displacement distribution of the flexible ring is investigated, and the effects of the system parameters on output torque are discussed. The results show that the current intensity of the coils, the airgap, the iron core length, and the position of the rigid ring have effects on the output torque for the drive system. The current intensity can be taken as the main control parameter of the output torque.
Online Adaptive Bearings Condition Assessment Using Continuous Hidden Markov Models
Authors: Cartella Francesco , Sahli Hichem
Published: March 2015

Condition assessment (CA) of bearings can be performed by using left-right hidden Markov models, because of the monotonically increasing pattern of the bearings degradation. Classical CA approaches assume that all possible system states are fixed and known a priori. The training of the system is performed offline at once with data from all of the system states. These assumptions significantly impede condition assessment applications in case that all the possible states of the system are not known in advance, or changes in environmental or operative conditions occur during the tool's usage. To overcome these limitations, we propose combining left-right continuous HMMs (CHMM) with a change point detection algorithm for (i) estimating, from historical observations, the initial number of the CHMM states and the initial guess of its model parameters and (ii) updating the state space as well as the model parameters during monitoring. Moreover, to deal with multidimensional sensor measurements, we propose using kernel principal component analysis for dimensionality reduction. Qualitative and quantitative evaluations of the proposed methodology have been performed using both simulated and real data from the NASA benchmark repository. Compared to state of the art techniques, the proposed methodology results in (i) an improvement of the HMM training phase in terms of iterations number; (ii) the detection of unknown states at an early stage; and (iii) an effective change of the CHMM's structure to represent the degradation processes more accurately in presence of unknown conditions.
Benchmark Numerical Simulations of Viscoelastic Fluid Flows with an Efficient Integrated Lattice Boltzmann and Finite Volume Scheme
Authors: Zou Shun , Xu Xinhai , Chen Juan , Guo Xiaowei , Wang Qian
Published: March 2015

An efficient IBLF-dts scheme is proposed to integrate the bounce-back LBM and FVM scheme to solve the Navier-Stokes equations and the constitutive equation, respectively, for the simulation of viscoelastic fluid flows. In order to improve the efficiency, the bounce-back boundary treatment for LBM is introduced in to improve the grid mapping of LBM and FVM, and the two processes are also decoupled in different time scales according to the relaxation time of polymer and the time scale of solvent Newtonian effect. Critical numerical simulations have been carried out to validate the integrated scheme in various benchmark flows at vanishingly low Reynolds number with open source CFD toolkits. The results show that the numerical solution with IBLF-dts scheme agrees well with the exact solution and the numerical solution with FVM PISO scheme and the efficiency and scalability could be remarkably improved under equivalent configurations.
Investigation of the Fluid-Solid Thermal Coupling for Rolling Bearing under Oil-Air Lubrication
Authors: Tong Baohong , Wang Guangyu , Sun Xiaoqian
Published: March 2015

An excellent oil-air lubrication system helps to improve rolling bearing's working conditions and thus extend its service life span. Flowing and heat dissipating characteristics of oil-air media inside bearing chamber are very complicated due to the fluid-solid thermal coupling. Effects of fluid-solid thermal coupling are neglected in all previous simulation efforts. A numerical model for simulating the flowing inside bearing chamber is developed here based on an analytical fluid-solid thermal coupling method under oil-air lubrication. The effects of the coupling of air-oil flowing and heat dissipating in bearing chamber are predicted. The simulation results indicate that the coupling is influential in the performances of the flowing in rolling bearing under oil-air lubrication. With consideration of the coupling, the turbulence intensity, the turbulent kinetic energy, and the temperature of the rollers are predicted to be lower because part of the heat is carried out by the flow due to the heat transfer. On the contrary, the turbulent dissipation rate gets higher when considering the coupling effects. It is also interesting that the coupling effects have little influence on the flow pressure and the velocity, which is manifested by a little higher predicted value when considering the coupling.
Effect of Cylinder Liner Oil Grooves Shape on Two-Stroke Marine Diesel Engine's Piston Ring Friction Force
Authors: Mohamad Salaheldin A. , Lu Xiqun , Zheng Qun
Published: March 2015

The dimensions, area densities, and geometry of macroscale surface textures may affect the performance of hydrodynamic lubrication interface. Reported in this paper are the investigations of the effect of surface textures bottom shapes on the friction forces between piston ring and cylinder liner for two-stroke marine diesel engine, using numerically generated textures and average Reynolds equation. These textures are on the cylinder liner surface in the form of circumferential oil grooves with different aspect ratios and different area densities. The hydrodynamic pressure distribution is also calculated using Reynolds boundary condition. The results revealed that the bottom shape could positively affect the friction between moving surfaces, as it could provide a microwedge or microstep bearing that tends to enhance the lubrication condition between piston ring and cylinder liner.
Identification of Dynamic Parameters for Robots with Elastic Joints
Authors: Zollo Loredana , Lopez Edoardo , Spedaliere Luca , Garcia Aracil Nicolas , Guglielmelli Eugenio
Published: March 2015

This paper presents a novel method for identifying dynamic parameters of robot manipulators with elastic joints. A procedure based on the Lagrangianm formulation of the dynamic model is proposed. Each term is inspected to search for a linear relationship with the dynamic parameters, thus enabling the linearization of robot dynamic model. Hence, the torque vector is expressed as the product of a regressor matrix, suitably defined by the vector of dynamic parameters. A parametric identification based on a least-squares technique is applied to determine dynamic parameters of robots with elastic joints. The correctness of the proposed procedure has been tested in simulation on two robotic structures with elastic joints of different complexity, that is, a 2-degree-of-freedom (dof) and a 6-dof manipulator, controlled with a PD control in the joint space.
Bionic Research on Bird Feather for Drag Reduction
Authors: Feng Beibei , Chen Darong , Wang Jiadao , Yang Xingtuan
Published: March 2015

To reduce friction drag with bionic method in a more feasible way, the surface microstructure of bird feather was analyzed attempting to reveal the biologic features responding to skin friction drag reduction. Then comparative bionic surface mimicking bird feather was fabricated through hot-rolling technology for drag reduction. The microriblet film was formed on a PVC substrate through a self-developed hot-rolling equipment. The bionic surface with micron-scale riblets formed spontaneously due to the elastic-plastic deformation of PVC in high temperature and high pressure environment. Comparative experiments between micro-structured bionic surface and smooth surface were performed in a wind tunnel to evaluate the effect of bionic surface on drag reduction, and significant drag reduction efficiency was obtained. Numerical simulation results show that microvortex induced in the solid-gas interface of bionic surface has the effect of shear stress reduction and the small level of an additional pressure drag resulting from pressure distribution deviation on bird feather like surface, hence reducing the skin friction drag significantly. Therefore, with remarkable drag reduction performance and simple fabrication technology, the proposed drag reduction technique shows the promise for practical applications.
Modeling the Speed Choice Behaviors of Drivers on Mountainous Roads with Complicated Shapes
Authors: Shao Yiming , Xu Jin , Li Benwang , Yang Kui
Published: March 2015

Roadway geometric features and pavement conditions can significantly affect driver behavior, particularly with regard to vehicle speed. This paper presents the development of an algorithm for speed selection for use in automated passenger car travel (without driver input) on mountainous roads with complicated shapes. The relationship between favorable driving speed and the geometric features of horizontal curves was established on the basis of driving experiments and spot speed observation data, and speed control models were established for driving on curves, curve approaches/departures, and tangents. The models developed can be used to calculate a driver's desired speed on any roadway with a defined geometry. The model considers the driver's behavior type and the vehicle's dynamic properties. This paper presents the results of simulation experiments on roads with small curve radii and narrow widths. The algorithms developed may be used for assisted and automated driving. Under automated driving conditions, speed control and speed change based on the algorithms developed make drivers feel natural as if they drive the car themselves.
An Alternative Algorithm for Optimal Design of Plate Heat Exchangers
Authors: Javid Seyyed Morteza , Farshidianfar Anoushiravan , Golparvar Seyyed Behzad
Published: March 2015

Due to the complex geometry of plate heat exchangers and thus a large number of variables affecting the performance of the exchangers, the design of these types of exchangers is quiet difficult. However, unlike the shell and tube heat exchangers which contain available data of design procedures, the design of plate heat exchanger is a monopoly of some certain manufacturing companies that make the problem even worse. In this paper, the objective is to minimize the number of plates in plate heat exchanger; in order to achieve that, a simple and yet efficient mathematical model is introduced for determination of the pressure drop and heat capacity of a plate heat exchanger in single- and multipass state and also a program was defined for determination of optimal solution based on this simple mathematical model for given operational constraints and plate type. In the end, the optimal solution will be compared to the answer of CAS200 commercial software and also it is shown that the effect of the start and end plates and transverse distribution in optimal solution is considerable.
Numerical Analysis of Flow Phenomena in a Residual Heat Removal Pump
Authors: Yuan Jianping , Hong Feng , Zhou Banglun , Zhang Fan
Published: March 2015

The hydraulic performances as well as the cavitation phenomena in a scaled residual heat removal pump were investigated by experimental and numerical methods, respectively. In particular, a 3D numerical model of cavitation was adopted to simulate the internal cavitating flow through the model pump. The hydraulic performances of the model pump predicted by numerical simulations were in good agreement with the corresponding experimental data. The main generation and evolution of attached cavitation throughout the blade channels at different cavitating conditions have been investigated using the vapor fraction ISO surface and in-plane velocity vectors. Results show that the low static pressure at the impeller inlet is the main reason for leading edge cavitation by correlation analysis of static pressure on the midspan of impeller. Cavitation proved to occur over a wide range of flow rates, producing a characteristic creeping shape of the head-drop curve and developing in the form of nonaxisymmetric cavities at design flow rate. Moreover, the occurrence of these cavities, attached to the suction surface of blades, was found to depend on the NPSHA value. Numerical and experimental results in this paper can provide better understanding of the origin of leading edge cavitation in residual heat removal pumps.
The Electrochemical Machining Analysis of Aeroengine Blade Based on Isogeometric Method
Authors: Wan Neng , Du Ke , Mo Rong , Chen Tao
Published: March 2015

Electrochemical machining is an important method for the blade in aeroengine. Analysis of electric field in machining gap is the basis of cathode design. For solving the low precision problem for sensitive boundary which is caused by traditional numerical analysis method, this paper proposed a method of promoting the analysis precision by using the isogeometric analysis. The NURBS basis functions are used to replace the Lagrange basis function for establishing the solving equations of the electrochemical machining gap. The problem of the noninterpolation feature belonging to the NURBS basis functions, which could bring the error for imposing Dirichlet boundary condition, is settled. At last, the superiority, including precision and the rate of convergence, of the isogeometric analysis is proved by the comparison test.