bluuebunny/crossref_metadata_2025 huggingface dataset:
Plantar Pressure Improvement after Correction of Hallux Valgus Condition — Static and Dynamic Approach
Authors: Stoia Dan Ioan , Toth-Taşcău Mirela , Pasca Oana , Vigaru Cosmina
Published: September 2013

The paper proposes a protocol used for data processing, designed to handling the foot pressure data recorded in human walking. This protocol represents a stage of a global protocol that deals with identification of some biomechanical parameters used in diagnosis and prediction. In order to validate the functionality of the data processing protocol, a lot of 10 patients suffering of Hallux Valgus deformity were recorded both before and after the surgery. The patients were divided into three age groups: 20-30, 40-50, 51-60. The measurements consist in recording of plantar pressure data in both dynamic (gait) and static way. This is an additional investigation to the clinical usual examinations in hallux valgus patients. The recorded data were averaged per each subject and then per whole lot. Based on determining the ground reaction force (GRF) variation in time and observing the foot pressures on static measurements, we can conclude that the static approach of evaluation of Hallux Valgus condition is no very reliable.
Biomechanical Modeling of Human Finger
Authors: Radu Panaitescu Liess
Published: September 2013

Many of the studies in the biomechanics of the human body made globally focused primarily on hand-arm. This segment of the human body is considered a "gateway" of vibrations to other parts of the body or to internal organs. A long-term exposure to these mechanical vibration (caused by vibrating hand equipment: drill, grinder, etc.) affects the soft tissues and may lead to a dangerous syndrome, that is particularly vibration white finger (VWF), which is narrowing of blood vessels, a phenomenon that in time and untreated can even cause gangrene. This article focuses on a dynamic model with three degrees of freedom of the human finger. Some dynamic characteristics, such as centre of gravity, stiffness and damping, using both a rigid body structure system and computer simulations can be determined after measuring the vibrations.
Corrective Analysis of the Parametric Values from Dynamic Testing on Stand of the Antiseismic Elastomeric Isolators in Correlation with the Real Structural Supporting Layout
Authors: Bratu Polidor
Published: September 2013

The paper presents the result of experimental research of the viscoelastic behavior of the antiseismic elastomeric isolators on stand, in laboratory, where the excitation is given only through harmonic instantaneous displacements. Based on the dynamic response under the form of the elastic and dissipation forces, in the time domain, the hysteresis loops and the stiffness, damping and durability to imposed repeated cycles parameters are determined. In this case, the order I dynamic system is free of added mass which makes the evaluation of its own damping to be estimated as equivalent damping with that of a complete system of 2ndorder with viscous damping.Using elastomeric isolators on site, for a base isolation project, either building or viaduct, imposes corrections of the experimental laboratory values considering the real conditions, function of the dynamic inertial excitation (earthquake, wind gusts, etc.) and of the response in instantaneous displacements.
Experimental Evaluation of the Hysteretic Damping of Elastomeric Systems at Low-Cyclic Harmonic Kinematic Displacements
Authors: Ovidiu Vasile
Published: September 2013

The paper presents the experimental results regarding the hysteretic behavior of elastomeric systems made in conformity with the European Standards SR EN 1337-3 and SR EN 15129. It is also mentioned that the hysteretic damping was determined by experimentally raising the hysteresis loop in a low-cycle harmonic regime, with a kinematic exterior excitation defined by a harmonic displacement law.
In this context, it is mentioned that the area of the hysteretic loops was determined instrumentally (in analogical representation of the signals) as well as under digital form, through a sampling of the physical signal, which allows a high precision of the determination.
Experimental Evaluation of the Damping Variation of an Elastomeric Device Harmonically Excited
Authors: Ovidiu Vasile
Published: September 2013

The results of the experimental tests, in dynamic regime, on antiseismic elastomeric devices, evidenced the fact that the internal damping represents a significant parameter tightly related to the specific shearing deformation of the elastomeric elements. Consequently, based on the final obtained results, correlation curves were raised meant to represent the variation of the equivalent critical damping ration (dynamic system of order I).
Strength Reduction Factors: A Unified Analytic Expression for Narrowband and Broadband Ground Motion Records
Authors: Craifaleanu Iolanda Gabriela
Published: September 2013

Strength reduction factors are an important component of the force modification factors used in the calculation of seismic code forces, as they account for the effect of the nonlinear hysteretic behavior of the structure. They are expressed as the ratio between the elastic strength demand and the inelastic strength demand induced in a structure by the earthquake. The evaluation of strength reduction factors has applications in the substantiation of seismic force modification factors in building design codes and in the direct application of the capacity spectrum method. The paper presents a study performed on two sets of accelerograms having different spectral content types, i.e. narrow frequency band records and broad frequency band records. Based on constantductility spectra of strength reduction factors, computed with 50% and 10% probability of exceedance, a unified analytic formula is developed, to describe the variation with ductility and vibration period of these factors. By modifying the values of the coefficients of the variables, the formula can be adapted for each type of spectral content. The formula is further refined, by determining a new set of coefficients, to also account for the influence of the predominant period of the ground motion in the case of narrow frequency band records.
Damage Identification of Cantilever-Type Structures by Using Only the First Natural Frequency and Mode Shape
Authors: Chun Young Soo , Chang Kug Kwan
Published: September 2013

Damage detection of a structure has drawn much attention in the aspect of maintenance and safety. In these aspects, vibration characteristics of a building have been constantly used in order to obtain a damage index of the whole building, but practical methodologies have not been presented yet. This study proposes a practical methodology to detect damage of a structure by using only the first natural frequency and mode shape of a building. The validity of the proposed methodology has been verified by experiments and numerical analyses. A result of verification confirms degree and location of damage may be detected with a relatively small error by the proposed methodology.
Non-Oscillatory Finite Compact Scheme for the Equations of Ideal Magnetohydrodynamics
Authors: Liu Li , Shen Yi Qing
Published: September 2013

Although the equations of ideal Magnetohydrodynamics (MHD) is a non-strictly hyperbolic system, they have a wave-like structure analogous to that of the hydrodynamics equations, various numerical schemes for hydrodynamics equations have been extended to solve the MHD equations. The finite compact (FC) scheme treats the discontinuity as the internal boundary and avoids the global dependence of the traditional compact schemes. By using a parameter-free shock detecting method, the computational domain is divided into a series of smooth regions and shock wave regions. In the shock wave regions, the shock capturing scheme is used to construct the numerical flux, and in the smooth regions the compact scheme is used, the flux of shock wave region is automatically the boundary formulation of the compact scheme. Hence, the FC scheme can resolve shock essentially non-oscillatory and achieve high order of accuracy in smooth region. This paper develops the non-oscillation finite compact scheme for the ideal MHD equations.
Research on Velocity and Inducted Magnetic Field of Conducting Flow in 2D
Authors: Liu Yang , You Ya Ge , Zhang Ya Qun , Cao Xue Ling
Published: September 2013

The purpose of this paper is to present the results of velocity and inducted magnetic field based on thedimensionlessgoverning equations of the incompressible, viscous, instant fluid from equation (1) to equation (6).We assumed a full developed and steady flow so that we can get the exact solutions. Firstly, we considered the situation of low magnetic Reynolds number and inducted magnetic field being ignored. Then secondly, we considered the situation of large magnetic Reynolds number. By comparing these two situations, we found two results: (1). theelectromagnetic force produced by the magnetic field changes the original velocity field a lot (Fig.2 and Fig.3); (2). the inducted magnetic field decreases with the decrease of magnetic Reynolds number. The results also prove that the inducted magnetic field can be ignored when the magnetic Reynolds number is less than or equal to 1 (Fig.5).
Preparation and Characteristics of the Micro/Nano Fibrils from the Wheat-Straw Treated by Enzyme
Authors: Liu Cong , Zhang Yang , Su Yong
Published: September 2013

Single-factor experiment was applied to get the optimum enzyme treatment condition: water bath in the oscillation trough at the frequency of 80 in 50°C with enzyme usage 35 IU/g for 48h. Transmission electron microscope (TEM), laser granularity distributing machine, Fourier transform infrared spectrometer (FTIR) and X-ray diffractor (XRD) were used to analyze the product with enzyme treatment. Observing by TEM, we could see large volume of micro/nanofibrils had gathered together, while fibre was 100-300 nm long and far less than 100nm radial, meeting the requirement of micro/nanofibrils. Being analyzed with laser granularity distributing machine, part of the product had reached the micro/nanolevel. Analyzing by FTIR, we can conclude that after enzyme treatment and ultrasonic dispersion cellulose had no change in functional groups. From the crystallinity atlas, we find the crystallinity of wheat-straw micro/nanofibrils improved from 65.55% to 72.99%, showing that cellulose enzyme destroyed the non-crystallizing field effectively
Implementation and Verification of High-Order Accurate Discontinuous Galerkin Method on 2-D Unstructured Grids
Authors: Zhao Wen Geng , Zheng Hong Wei
Published: September 2013

In this paper, the discontinuous Galerkin method (DG) is applied to solve the 2D Euler equation. DG can be easily used in the unstructured girds, which has advantages in dealing with problems with complex boundaries. High order accuracy is achieved by higher order polynomial approximations within elements. In order to capture the shock without oscillation, the limiter is also applied. The performance of DG is illustrated by three numerical experimental tests, which show the potential of DG in engineering applications. The vortex propagation problem is to verify high-order accuracy of DG, while Sob problem and forward step problem are used to illustrate the ability to capture shock.
Software and Hardware Design of a Acoustic Fault Detecting Instrument
Authors: Wang Hong Wei , Wang Xiao Ni , Tian Xu , Du Gai Hong , Tian Yang Meng , Rong Qi Mu Su , Zhang Wen Kai
Published: September 2013

This paper is about a kind of instrument which can detect the fault object by acoustic sensor detecting the object Surface acoustic signals, through the analysis of the acoustic signal of the intensity and frequency content, so determining the object if abnormal conditions occur. Design by using Piezoelectricity material as the sensing head, the signal processing circuit is based on SH79F32 microcontroller as the core, the single-chip microcomputer, integration with ADC, the analog signal from the sensor to convert them into digital signals, in the procedure, carries on processing to the signal frequency components, filter out low-frequency components, acoustic signal was finally measured on a screen display. including hardware design, production, processing, software programming, to obtain the acoustic fault detector, and to test its performance, results show successful.
Analysis of the Quality of Rapid Manufacturing Technology Based on the Silicone Rubber Mold
Authors: Chen Xue Fang , Du Jian Hong , Li Hong Wei
Published: September 2013

The rapid manufacturing processes include making prototype mold, making silicone rubber mold and pouring parts. According to the study of rapid manufacturing based on silicone rubber mold, factors that impact the characteristics of products, the quality of surface and the accuracy of dimension are discovered. The curing temperature and time affect the properties of products. The smoothness of prototype surface, gate position, exhaust port position, channel distribution and pouring speed affect the quality of the products surface. The shrinkage of the material affects the accuracy of products dimension. Moreover, some measures and methods that improve the products quality also be illustrated.
3-Phase 4-Wire VIENNA Rectifier Used in the Resistance Spot Welding Inverter Power Supply
Authors: Zhang Yong , Teng Hui , Ma Tie Jun , Xie Hong Xia , Wan Peng
Published: September 2013

Considering the distortion factor, the large power resistance spot welding (RSW) inverter power supplys actual power factor (PF) is very low. In this paper, the 3-phase 4-wire three-phase/switch/level (VIENNA) rectifier is proposed to realize the power factors correction (PFC). Firstly, an equivalent load model of the back-stage in the RSW inverter power supply is established, thus the real load of this PFC circuit can be archived. Then, the 3-phase 4-wire VIENNA rectifier PFC circuit is analyzed with the simulation software of Pspice. Finally, an experimental circuit power of 3kW is designed. Experimental results show that the PF of this system can be increased to 98.6% that demonstrates the practicability of the 3-phase 4-wire VIENNA rectifier in RSW inverter power supply.
Subsystems Risk Assessment of the CNC Machine Tools
Authors: Zhu Xiao Cui , Chen Fei , Wang Ji Li , Yang Zhao Jun , Wang Li Ding , Jia Yu Hui
Published: September 2013

The subsystems risk assessment is an important problem for reliability study of the CNC machine tools. A novel method based on reliability different function for assessing the subsystem risk was proposed. Firstly, failure data and subsystem could be described. Secondly, the subsystem reliability of the CNC machine tools was estimated using the mean rank method, since the failure data of subsystem is the less. At the same time, Weibull distribution parameters were estimated using the Maximum Likelihood Estimation (MLE) .Thirdly, the reliability different function set of the CNC machine tools was attained by assuming that each subsystem was between absolutely reliable and non-absolutely reliable, and the comparative analysis of subsystem reliability was conducted for assessing the subsystems risk. Finally, a case example analysis proved that the proposed method could assess subsystem risk of the CNC machine tools rapidly and accurately.
Analysis of Human Hand Kinematics: Reaching Upward Movement
Authors: Rahman Hisyam Abdul , How Goh Chok , Fai Yeong Che , Ming Eileen Su Lee
Published: September 2013

Reaching movement is one of the important training for stroke patient to recover the impairment arm as this movement is critical for activities of daily living. A studied conducted to investigate the minimal requirement that a rehabilitation robot should have in order to train reaching movement in upward after the impairment arm start to overcome gravity. Result show some convex, linear and concave trajectory during reaching movement in upward direction depended on the level of the target distance. This study can be applied for designing a new simpler or improvement of the existing rehabilitation robot to train the upper limb for stroke patient.
A Lightweight Message Encrypt Protocol for Electronic Commerce
Authors: Zhong Xiao Jun , Yao Lu
Published: September 2013

In this paper, we propose a publicly verifiable batch encryption scheme. It allows a trusted entity to verify that two or more cipher texts hind the same message without revealing it. The message can also be verified by running a single PVE scheme with the same public value for each cipher text. However, it requires more computation than our scheme. According to our analysis, our scheme can reduce the overhead of computations by 66%. Furthermore, our scheme can be applied to voting and network testing to prove the fairness.
Study on the Optimize Strategies of Gene Expression Programming
Authors: Gao Xin Wen , Guan Ben Bo , Guan Xing Jian
Published: September 2013

The purpose of this paper is to improve the efficiency of the Gene Expression Programming (GEP) algorithm. The GEP algorithm is an evolutionary computation. It inherits the characteristics of Genetic Algorithm and Genetic Programming. Through its own characteristics, the GEP algorithm can get the optimal solution of the complicated problem. So, the GEP algorithm has achieved good results in many areas. However, there are also some inevitable drawbacks about the GEP algorithm itself. This paper proposes 5 deficiencies aspects of the GEP algorithm (expression meaning, fitness calculation, local convergence, variable selection, genetic operations, selection of genetic operation rates), and gives the corresponding solutions.
The Asymmetric PCF Control Technology of Gated Service Based on Continuous-Time
Authors: Zhao Guang Lan , Ding Hong Wei , Guo Ying Ying , Zhao Yi Fan , Hao Ya Nan
Published: September 2013

The paper starts with building system mathematical models and defining system parameters and working conditions to analyze the system model and performance, using the embedded Markov chain and probability generating function. The paper also deduces the accurate closed expression of the mean queue length and cycle time, gets approximate analysis expression of the mean waiting time well, and also verifies the correct theoretical analysis by simulation.
Part Features Oriented Optimizing of Manufacturing Resources for Cloud Manufacturing
Authors: Dong Zhao Yang , Zhang Lin
Published: September 2013

The research is targeted at the bottleneck technology of manufacturing resources optimizing configuration in cloud manufacturing, namely, the modeling of manufacturing resource and manufacturing task, the intelligent searching of manufacturing resource, and the optimizing of executive processing routes. Manufacturing resources are classified by manufacturing features. The framework of ontology concept is constructed, and the relationship among various concepts is made clear. Then the ontology model of manufacturing resources is constructed. The part features of manufacturing tasks are extracted, and the part features are expanded to include the information of manufacturing methods. Then the ontology model of manufacturing task is constructed. The concept tree method is adopted to compute the semantic similarity between manufacturing resource concept tree and manufacturing task concept tree, so to realize the mapping of manufacturing resource ontology to manufacturing task ontology, and the intelligent searching of manufacturing resources is accomplished. The best manufacturing resources are chosen from candidate resources for each job in processing route during the optimizing of executable processing routes. This problem belongs to a complicated multi objectives, multi choices, and multi constraints knapsack problem. A compromise based parallel multiple objective genetic algorithm is proposed to solve it. Finally, the compromised solution is obtained for the decision-maker.
An Experimental Research on Abrasive Water Jet Polishing of the Hard Brittle Ceramics
Authors: Lv Zhe , Huang Chuan Zhen , Wang Jun , Zhu Hong Tao , Yao Peng , Liu Zeng Wen
Published: September 2013

Abrasive water jet (AWJ) technology, due to its potential advantages, is a promising machining method for precision machining brittle materials. In this research, the AlN ceramics was polished using an AWJ machining system. A considerable processing quality has been achieved and a reduction up to 62% of the surface roughness has been obtained. Effects of different process parameters on the surface roughness of the polished workpiece were analyzed. Under the current conditions of the experiments, using a lower impact angle, smaller abrasives and a lower nozzle traverse speed may be appropriate for polishing AlN ceramics.
Experimental Investigation on Drilling Force and Hole Quality when Drilling of T800S/250F CFRP Laminate
Authors: An Qing Long , Xu Jin Yang , Cai Xiao Jiang , Chen Ming
Published: September 2013

High-strength carbon fiber reinforced plastic (CFRP) T800S/250F is used as the large commercial aircraft material for manufacturing the main load-bearing structural components. Drilling is the mostly used in final machining process of CFRP laminates, while the delamination and burrs occur frequently at the drill exit in the CFRP laminate. In this paper, the machinability of T800S/250F was investigated in term of drilling force and hole quality by using a twist drill and a dagger drill. The experimental results indicated that high spindle speed and low feed rate favor the reduction of thrust force for both drill bits. High spindle speed is a preference to gain the good hole quality at drill exit especially for the dagger drill, which also shows excellent drilling performance than the twist drill and was more suitable for drilling of T800S/250F CFRP laminate.
Effects of Cutting Conditions on the Machinability of Stainless Steel Formed by Laser Cladding
Authors: Wang Bing , Liu Zhan Qiang , Su Lun Chang , Zhang Lin Qing
Published: September 2013

The paper investigates the effects of cutting conditions on the machinability of stainless steel coatings manufactured onto AISI 1045 steel by laser cladding technology. Two kinds of CBN (cubic boron nitride) tools with different corner radius and two different depths of cut were adopted in the experiments. Cutting force during machining, surface roughness and microhardness of machined surface were measured and analyzed. The results show that both the cutting force and surface roughness increase with the increase of depth of cut. When the other cutting parameters are identical, the surface roughness decreases with the increase of tools corner radius while the variations of different cutting force components present different tendencies. The microhardness of the machined surface and its varied gradient in the direction of depth of cut increase with the increase of tools corner radius. The experiment results will provide valuable suggestions for optimization of cutting performance for laser cladding coatings in order to obtain excellent surface quality.
Microstructure and Mechanical Properties of Al2O3-TaCw Ceramic Cutting Tool Materials
Authors: Zhao Guo Long , Huang Chuan Zhen , Liu Han Lian , Zou Bin , Zhu Hong Tao , Wang Jun
Published: September 2013

Three kinds of in-situ growth TaC whiskers toughening Al2O3 matrix ceramic cutting tool materials were prepared by two steps, which were in-situ synthesis of TaC whiskers in Al2O3 matrix powder by carbothermal reduction process and hot pressing of the composites respectively. The preparation process, microstructure, mechanical properties and toughening mechanisms of the composites were investigated. The in-situ synthesized TaC whiskers had a diameter of 0.1-0.5μm and an aspect ratio of 10-30. The composite containing 20vol.% TaC had the optimal comprehensive mechanical properties with flexural strength of 638MPa, fracture toughness of 6.5MPa·m1/2 and hardness of 17.4GPa. The improvement of the mechanical properties was attributed to the TaC particles and whiskers which induced the toughening and strengthening effects such as crack deflection, crack branching, grain and whisker fracture, interface debonding and whisker pullout. The fracture mode of the composites was the combination of intergranular and transgranular fracture which also improved the mechanical properties of the composites.
An Indicative End-Milling Condition Decision Support System Using Data-Mining for Difficult-to-Cut Materials Based on Comparison with Irregular Pitch and Lead End-Mill and General Purpose End-Mill
Authors: Kodama Hiroyuki , Hirogaki Toshiki , Aoyama Eiichi , Ogawa Keiji
Published: September 2013

Data-mining methods using hierarchical and non-hierarchical clustering are proposed that will help engineers determine appropriate end-milling conditions. We have constructed a system that uses clustering techniques and tool catalog data to support the determination of end-milling conditions for different types of difficult-to-cut materials such as austenitic stainless steel, Ni-base superalloy, and titanium alloy. Variable cluster analysis and the K-means method were used together to identify tool shape parameters that have a linear relationship with the end-milling conditions listed in the catalogs. The response surface method and significant tool shape parameters obtained by clustering were used to derive end-milling condition decision equations, which were used to determine the indicative end-milling conditions for each material. Comparison with the conditions recommended by toolmakers demonstrated that our proposed system can be used to determine the cutting speeds for various difficult-to-cut materials.
Cutting Edge Preparation of PCBN Inserts
Authors: Denkena Berend , Köhler Jens , Ventura C.E.H.
Published: September 2013

In order to increase tool life and workpiece surface quality, cutting processes with geometrically defined cutting edges demand inserts with a targeted prepared edge. For example, chamfers are largely used in many processes to provide edge strengthening without damaging the chip flow. In order to achieve a stable and reliable cutting process, small and uniform chamfers are necessary. In this context, the influence of grinding parameters on the edge quality and on the chamfer width deviations is investigated. It was found that larger abrasive grains increase edge chipping and that elastic deformation during chamfer grinding at insert corner radius is the main responsible for chamfer width deviation.
Numerical Investigation on Effect of Rounded Cutting Edge Radius in Milling of Ultra-High-Strength Steel 30Cr3SiNiMoVA
Authors: Wang Chang Ying , Tian Jia Jin , An Qing Long , Chen Ming
Published: September 2013

Ultra-high-strength steel 30Cr3SiNiMoVA (30Cr3) which has excellent mechanical properties is usually used to manufacture the key parts in aviation industry. Precision hard milling is an efficiency way to machine 30Cr3 instead of grinding. Rounded cutting edge radius has important influence on the machining process due to small depth of cut. In order to better understanding the influence of rounded cutting edge radius, cutting forces, cutting temperature, critical depth of cut, etc., is analyzed by using finite element method (FEM). The results show that cutting forces in theydirection are more sensitively to the rounded cutting edge radii. Ploughing effect is also observed at the end of the climb milling process and it has significant influence on the quality of the machined surface. Simulation reveals that the increment of rounded cutting edge radius can lead to the increment of critical depth of cut correspondingly and the proportionality factor is about 14%.
Predicted Model of Cutting Force for Single Diamond Fast Milling Hard-Brittle Materials
Authors: Hu Shan Shan , Chen Cheng Gang , Hu Ying Ning , Zheng Dong Rui
Published: September 2013

t is known that cutting force is the key to reasonably select cutting parameters, and the base to study the cutting mechanism. Genetic Algorithm and multiple regression analysis were adopted to achieve cutting force predicted model of multi-diamonds fast milling hard-brittle materials with defined diamond grains pattern by single diamond fast milling hard-brittle materials experiments. Results show that cutting force predicted model by genetic algorithm has higher precision than that model by multiple regression, and the cutting force prediction method based on genetic algorithm is more suitable for those hard-brittle materials which components are relatively soft and simple. Predicted model can afford another study direction for processing analysis of diamond tools, tools making and processing parameters selection from the view of diamond grain practice cutting.
Study on Thermal Influence of Grinding Process on LiTaO3
Authors: Hang Wei , Zhou Li Bo , Shimizu Jun , Yuan Ju Long
Published: September 2013

As a typical multi-functional single crystal material, Lithium tantalate (LiTaO3 or LT) exhibits its excellent electro-optical, pyroelectric and piezoelectric properties, and has now been widely applied into many applications, especially in the telecommunication field. However, the most critical issue in the process is its pyroelectric effect and piezoelectric effect which potentially leads to crack initiation during grinding. Because it is rich in plasticity, LT demands larger specific energy for material removal. As the most machining energy is eventually converted into heat, LT undergoes a rapid rise in temperature during the grinding process, thus highly risks in thermal shock. In order to clarify the thermal influence on the grinding process of LiTaO3, the effects of coolant temperature, diamond grinding wheel geometry and material of substrate are investigated in this research. The experimental results show that the increasing rate of grinding torque (or force) and surface roughness are two major factors dominating the crack initiation during grinding of LT wafers. Via a DOE (design of experiment) analysis, coolant temperature and wheel type stand out as the main factors influencing on the increasing rate and wafer surface roughness.
Study of Cluster Magnetorheological-Chemical Mechanical Polishing Technology for the Atomic Scale Ultra-Smooth Surface Planarization of SiC
Authors: Zhu Jiang Ting , Lu Jia Bin , Pan Ji Sheng , Yan Qiu Sheng , Xu Xi Peng
Published: September 2013

The growth of epitaxial layer of SiC wafer requires the surface of SiC substrate to reach an atomic scale accuracy. To solve the problems of low machining efficiency and low surface accuracy in the polishing process of SiC wafer, a novel ultra-precision machining method based on the synergistic effect of chemical reaction and flexible mechanical removal of the magnetorheological (MR) effect, the MR-chemical mechanical polishing (MRCMP) is proposed. In this technique, magnetic particles, abrasives and chemical additives are used as MR-chemical polishing fluid to form a cluster MR-effect flexible polishing platen under an applied magnetic field, and it is expected to realize an atomic scale ultra-smooth surface planarization with good controllability and high material removal rate by using the flexible polishing platen. Polishing experimental results of C surface of 6H-SiC crystal substrate indicate that an atomic scale zero-defect surface can be obtained. The surface roughness of C surface of SiC wafer decreased from 50.86nm to 0.42nm and the material removal rate was 98nm/min when SiC wafer was polished for 60 minutes.
A Model of the Fluid Convective Cooling in Grinding Process
Authors: Zhang Lei , Morgan Michael N.
Published: September 2013

The grinding process has particular interest in that contact temperatures have great significance for quality and integrity of machined surfaces. Hardened surfaces may be damaged by softening and or being stressed, being hardened or re-hardened, burned or cracked. It is important in grinding for the fluid to remove heat from the grinding contact zone to avoid thermal damage to the workpiece surface and/or sub-surface layers. The cooling effect of grinding fluid can be quantified by the convective heat transfer coefficient (CHTC) acting in the grinding zone. This paper presents values of the CHTC based on measured grinding temperatures. The paper also presents a new convective heat transfer model based on principles of applied fluid dynamics and heat transfer. Predicted values for the CHTC calculated from the model are compared with results from experiment obtained under a range of grinding conditions and with experimental data. The results demonstrate that the new CHTC model improves the accuracy of prediction and helps explain the variation in the value of CHTC under varying process conditions. Results also show that convection efficiency strongly depends on the grinding wheel speed, grinding arc length and fluid properties.
Effect of Contact Stiffness of Grinding Wheel on Ground Surface Roughness and Residual Stock Removal of Workpiece
Authors: Yamada Taisei , Lee Hwa Soo , Miura Kohichi
Published: September 2013

In the grinding operation, grinding wheels are deformed by grinding forces, so that residual stock removal of the workpiece takes place. Since this residual stock removal of the workpiece causes low machining efficiency and deterioration of machining accuracy, high hardness grinding wheels may be selected in order to obtain high machining efficiency and/or high quality machining accuracy. On the other hand, when grinding operations used by low hardness grinding wheels are carried out, it is well known that ground surface roughness is smaller than in case of higher hardness grinding wheels. From such a viewpoint, this study aims to investigate experimentally the effect of the contact stiffness of grinding wheel on the ground surface roughness and the residual stock removal of the workpiece. Grinding operations were carried out using three grinding wheels which are different hardness type, and ground surface roughness and residual stock removal of the workpiece were measured. The contact stiffness of grinding wheel was calculated by a support stiffness of single abrasive grain and a contact area between grinding wheel and workpiece. Comparing the contact stiffness of grinding wheel with the ground surface roughness and the residual stock removal of the workpiece, it was known that ground surface roughness increases and residual stock removal of workpiece decreases with increaseing the contact stiffness of grinding wheel. From these results, since elastic deformation of the grinding wheel changed depending on the suppot stiffness of single abrasive grain, it was clarified that the ground surface roughness and the residual stock removal of the workpiece were changed by the contact stiffness of grinding wheel.
Development of CMM Auxiliary Equipment for Tiny Hole Measuring
Authors: Chen Feng , Bing Zhi Gang , Li Shang Hui , Cheng Li , Zhang Zhi Quan , Chen Jia , Yang Yi
Published: September 2013

According to the limited measurement range of specific coordinate measuring machine (CMM), a reverse test method was put forward, and an auxiliary measuring equipment for tiny hole was developed. A measuring method for tiny hole was formulated, which using gauge head trigger signal of CMM as the test signal. The principle which was the tiny hole moving but not moving gauge head was used and the corresponding measurement software was designed so that the small measurement range was expanded. The measurement precision influence factors were analyzed and the measurement scheme was optimized. The results indicate that: then the measurement range of tiny hole is expanded to 1.0mm based on the combination of auxiliary equipment and CMM. The precision error is 0.004 mm which meets the measurement requirements.
Optimization Design for Gun-Receiver Materials Belt Grinding Based on Orthogonal Experimental Method and Grey Relational Analysis
Authors: Chen Yu Hui , Huang Yun , Huang Yao
Published: September 2013

In order to change the current situation of gun-receiver manual polishing, the paper presents a new process for abrasive belt grinding of gun-receiver material (C50 steel). Orthogonal test were conducted with abrasive belt grinding of C50 steel to do research on material removal rate and surface roughness. The best parameter combination to the optimization design which can guarantee high material removal rate and low surface roughness was obtained by using grey relational analysis method and verified by experiments. The above mentioned research not only can improve the removal rate of C50 steel, but also do help to prolong the service life of the belt. Whats more, it can guide a theoretical significance and practical value to the production practice.
The Dynamic Analysis of Micro-Scale Edge in the Process of Micromilling
Authors: Gong Ya Dong , Zhang Jin Feng , Cheng Jun , Wen Xue Long , Wang Chao , Yin Guo Qiang
Published: September 2013

The micro-processing technology has gradually become a hot topic problem, especially in micro-scale milling chatter prevention with the development of the information age. In allusion to the actual case of micro-milling, the dynamic theoretical research is analyzed in-depth about the Fourier method and the average tooth angle method. Compared to two ways, the former is close to the actual processing requirements. The lobes are obtained use the two ways. Micro milling parameters are selected in the stable area and unstable region. Stable and non-stable curve and surface quality of machined parts are obtained after micro-milling test. The chatter points, non-chatter point and uncertain point are obtained in the high spindle speed, which are consistent with theoretical analysis. In contrast, the distribution of chatter points in the low-speed spindle speed. The reason is that the damping effect is produced in the micro-scale milling process. The research of micro-scale milling chatter, which has a certain significance to improve parts of precision machined parts, reduce the wear and tear of the micro-milling blade and extend micro-tool life.
Surface Layer Damage of Silicon Wafers Sliced by Wire Saw Process
Authors: Kang Ren Ke , Zeng Yan Fen , Gao Shang , Dong Zhi Gang , Guo Dong Ming
Published: September 2013

Wire saw process is widely used in the machining of hard and brittle materials with low surface damage and high efficiency. Cutting of silicon wafers in integrated circuit (IC), semiconductor and photovoltaic solar industries is also generally using wire saw process. However, the surface layer damage induced by wire saw process will seriously decrease the wafer quality and increase the process time and production costs of the post grinding and polishing. The surface layer qualities of the silicon wafers sawed by the different wire saw processes was investigated in this paper. The characteristics of surface roughness, surface topography and subsurface damage of silicon wafers sliced by the fixed abrasive and the loose abrasive wire sawing respectively were compared and the corresponding reasons were analyzed.
Research on ELID Grinding Performance of GCr15 Steel
Authors: Guan Jia Liang , Ma Xin Qiang , Zhang Xiao Hui , Zhu Li Li , Wang Zhi Wei
Published: September 2013

The electrolytic in-process dressing (ELID) grinding technology was adopted for ultra-precision grinding experiments of GCr15 bearing steel. The experiments show that: grinding depth, electrolysis gap and wheel peripheral velocity are the main factors to affect the surface quality. With the electrolysis gap of 0.5mm, the grinding depth of 0.1μm, and the wheel peripheral velocity of 18m/s, the grinding effect can achieve optimal and the machined surface roughness can obtain Ra0.006μm.
Experimental Investigation of Material Removal Mechanism in Grinding of Alumina by Single Grain Scratch Test
Authors: Tawakoli Taghi , Kitzig H. , Lohner R. D.
Published: September 2013

Alumina is a material that is frequently used in high performance applications. Grinding of alumina is usually associated with micro-cracks which deteriorate surface quality. In order to get a deeper knowledge of the characteristics of material removal mechanisms in alumina during grinding with and without ultrasonic vibration of the workpiece, single grit scratch tests were performed in this research. The effect of the ultrasonic vibrations and cutting speed on the material removal mechanism of alumina was investigated in the chip thickness range of 0.53 μm which is common in precision grinding operations. It was shown that the material pile-up decrease with higher cutting speed. On the other hand, the transition from ductile to brittle mode of material removal occurs earlier in higher cutting speeds. The ultrasonic vibrations showed great influence in the cutting speed 30 m/s in reducing the pile-up values.
Using the Superficial Resonant Peak and PCA for Determining the Gold Nanoparticle Diameter
Authors: Martínez-Espinosa Juan Carlos , Cordova-Fraga Teodoro , Reyes-Pablo Aldelmo , Vargas-Luna Miguel
Published: September 2013

A model resulting from principal component analysis and assessment based on surface resonant peak of UV-VIS spectrum to determine the diameter of gold nanoparticles is presented in this paper. Six different diameters were analyzed by using the absorption spectra in the range from 400 nm to 700 nm. Commercial TED-PELLA gold colloid nanoparticles with diameters between 20 nm and 80 nm were measured. Preliminary results suggest the usefulness that this model may have on the characterization of nanostructured materials in colloidal suspension, as well as its application in manufacturing protocols standardization of nanoparticles.
Synthesis and Characterization of Reactive Michler's Ketones
Authors: Huang Qing Hua , Dou Xiao Qing , Bai Xiong Xiong , Hu Zhong Yu , Cheng Chuan Jie
Published: September 2013

Two novel reactive Michlers ketones were designed and easily synthesized in moderate yields. UV-absorption spectra showed that the reactive Michlers ketones absorbed light more efficiently than their bromide reactants. In practice, the Michlers ketones can act as both a photoinitiator and a co-photoinitiator to produce UV-cured cardanol resin in the absence of any other photoinitiators and co-photoinitiators.
Crystal Field Analysis of the Magnetization Curves of HoFe11Ti under High Pressure
Authors: Su Gang
Published: September 2013

The crystalline electric field parameters Anmfor HoFe11Ti under different pressures were evaluated by fitting calculations to the magnetization curves measured on the single crystals at several temperatures. It was found that magneto-crystalline anisotropy has been changed by high pressure and the Anmfor HoFe11Ti under high pressures are strikingly different from Anmfor the corresponding HoFe11Ti H with interstitial hydrogen atom.
Functional Efficacy of Omu-Aran 132/33kV Electricity Transmission Substation-Network Arrangement
Authors: Melodi Adegoke Oladipo , Aremu S.O.
Published: September 2013

This is one in a series of need driven studies to evaluate the efficacy of power delivery of radial 132/33 kV substation-network arrangements under prevailing load conditions, which represents communities expansions and social developments. The specific condition of Omu-Aran 132/33 kV substation-network arrangement (SNA), which supplies electricity to 5 load-communities in 4 respective States with similar demand cultures, was examined. Outgoing 33kV Network lines (NLs) were designated according to the names of their respective termini-cities. The description of network elements obtained from the network control centres, and network parameters were evaluated using standard formulas. From time series logged data (2007-2010) at the SNA, the maximum power statistics were evaluated to define the peak load conditions on the NLs. The SNA was modelled mathematically for load flow computational experiments using, predominantly, Bus Admittance Matrix method. Efficacy of power delivery was analysed using, mainly, voltage and thermal capacity criteria. An analysis of the results established substantial and inadmissible voltage and power losses between substation and load-communities on the existing 33 kV network lines; efficient normal mode use of these lines requires implementation of drastic load shedding, network reconstruction or reinforcement by voltage and power saving requirements.
Prepaid Meter in Nigeria: The Story so Far and the Way Forward
Authors: Orukpe P.E. , Agbontaen F.O.
Published: September 2013

The prepaid meter was introduced in Nigeria to aid revenue collection and generation by Power Holding Company of Nigeria (PHCN) in 2006 as well as abolished meter reading and estimated billing. Since its introduction there are still some challenges being faced by consumers and the power network operator. In this paper, we examined the Nigeria power sector, prepayment meter, advantages and disadvantages of the prepaid meter and smart meter in Nigeria. Finally, we make some recommendations.
Assessing Service Quality in a Telecommunication Firm in Upper East Region of Ghana
Authors: Oyetunji Elkanah , Bae Jacob
Published: September 2013

Service quality is crucial to the continued and successful functioning of any business. The purpose of this paper is to assess the service quality delivered by a telecommunication firm (located in Navrongo, upper east region of Ghana) to its customers. The survey questionnaire which was based on a universally accepted perceived service quality survey model (called SERVQUAL) for measuring service quality was used to collect data from the firms subscribers. The SERVQUAL consists of twenty two items measuring the five essential dimensions of service quality (Tangibles, Reliability, Responsiveness, Assurance and Empathy). A total of 100 subscribers of the telecommunication firm were conveniently sampled. The data obtained were analyzed using the Statistical Package for Social Science (SPSS) version 17.0. Using the gap analysis technique (which measures the difference between the subscribers perceptions and expectations of the service rendered by the firm), the results shows that the firm needs to improve their service in all the five dimensions of service quality covered in this study (a negative value of service quality was obtained in all the five dimensions).
Estimating the Power Requirement of a Design of Fish Robot Based on Teleost Specie of Fish - Mackerel
Authors: Afolayan M.O. , Yawas D.S. , Folayan C.O. , Aku S.Y.
Published: September 2013

The energy required to propel a biologically inspired robot in the form of a fish (mackerel) model using rubber (as the biomimetic material) for its joints is presented in this paper. It was found that the design will need approximately 0.81W of energy to handle the maximum dynamic torque of 0.0592850Nm that will be generated when using Futaba S3003 remote control servo motor to drive the peduncle. The fish robot designed was tested by making it to swim in a stationary body of water. It was found to be capable of swimming for about 30minutes compare to the calculated 2.7hrs hours using 4 built in 900mAh Li-Po battery (connected in parallel) while cruising at the speed of 0.985m/s.