bluuebunny/crossref_metadata_2025 huggingface dataset:
International Development Partnerships and Diffusion of Renewable Energy Powered Lighting Technologies in Off-Grid Communities in Developing Countries
Authors: Platonova Inna
Published: April 2012

Worldwide, 1.4 billion people virtually live in darkness after sunset. New lighting technologies, such as light emitting diodes (LED), powered by renewable energy allow non-electrified communities to access for the first time in their lives clean, durable, affordable, and higher quality lighting service. The international NGOs play an important intermediary role in diffusion of these technologies to off-grid communities and commonly operate via development partnerships. With the goal of providing insights into the nature of these partnerships and factors that influence their effectiveness, the exploratory case study was conducted which examined and compared development partnerships promoting renewable energy powered lighting technologies in off-grid indigenous communities in Talamanca, Costa Rica. The study acknowledged the catalytic role of the international NGOs and emphasized the centrality of locally embedded organizations and their capacities in successful implementation of development interventions. A set of factors was identified that contribute to the effectiveness of the development partnership in renewable energy in off-grid communities.
Local Innovation System in Emerging Economies
Authors: Boiola Jorge
Published: April 2012

Systems of innovation are highly dependent on local conditions, where national boundaries give the general platform to it, but local systems play a key role in the path to development. In the developing world this is even more important. Córdoba, Argentina, is the case of a developing region in a developing country. The study goes in the direction of gathering and interpreting data from the three mayor players of its innovation system: government, universities, and private companies, assessing the links among them and establishing conclusions about how they work as a system. Finally, it makes a proposal for the improvement of the local system of innovation to the different forces and the policymakers of the province. The study shares a common ground with similar regions around the world, and its lessons are applicable to them.
Internationalization Strategies of Chinese Pharmaceutical Firms
Authors: Zhao Jingyuan
Published: April 2012

China’s pharmaceutical market value is about USD 110 billion in 2009, and it has become the world’s second largest market. Chinese pharmaceutical firms are becoming a growing player in the global pharmaceutical chain. Through empirical research, this chapter summarizes the internationalization experience of Chinese pharmaceutical firms, finds that the effective strategies of international market entry are product upgrading along the industrial chain, international certification and cooperation, outsourcing and licensing, and other paths of overseas expansion, and presents that pharmaceutical firms in emerging markets should choose suitable entry paths and strategies according to their own advantages, learn the experience of internationalization from leading firms in emerging market, and gradually enter the standard market.
On the Latest Times and Float Times of Activities in a Fuzzy Project Network with LR Fuzzy Numbers
Authors: Sireesha V. , Shankar N. Ravi , Rao K. Srinivasa , Rao P. Phani Bushan
Published: April 2012

In this paper, the authors propose a new method to compute the fuzzy latest times and float times of activities for a project scheduling problem with fuzzy activity times. The authors have considered LR fuzzy numbers to represent the activity times. As the data of the problem are LR fuzzy numbers, the authors have shown that the results are also in terms of LR fuzzy numbers. Total float time of each activity can be found by this method without using the forward pass and backward pass computations. The authors use an example to illustrate the method. This paper shows the advantages of this method over the existing methods with great clarity. The proposed method illustrates its application to fuzzy critical path problems occurring in real life situations.
Emergency Preparedness
Authors: Russo Marianne Robin , Bryan Valerie C. , Penney Gerri
Published: April 2012

Since 9-11, emergency preparedness has been the focus on federal, state, tribal, and local levels. Although current research describes emergency management response, many barriers may exist that effect response systems, including the role of first responders, social vulnerability, and the way technology interfaces with these variables. Several factors determine the success of emergency preparedness and its ultimate impact on the health and safety of the community, including social media response, Community Response Grid (CRG) and social networks for older adults, emergency Internet and Community Technology (ICT) training within tribal communities and graduate schools, and programs and innovative emergency management policies for ethnically and racially diverse populations. Negotiating these issues, the character and incidence of emergency technology benefits the adult experiencing an emergency by: a) obscuring the constructs of social and class hegemony; b) mitigating future emergency problems when new procedures and policies that depend on ICT are rendered; c) examining barriers that could hinder lifesaving emergency procedures; and d) creating a community identification and a community collaborative bond so disadvantaged communities are responded to in an expedient manner.
Analysing the Intellectual Structure of E-Service Research
Authors: Di Guardo Maria Chiara , Galvagno Marco , Cabiddu Francesca
Published: April 2012

Despite the importance that e-service is gaining among firms and public administrations, academic research on this topic is still in its infancy (Santos, 2003), and relatively little work has been carried out. Although prior analyses have examined the rise and fall of specific theories or research topics within the e-service research field (Rust & Lemon, 2001; Rust & Kannan, 2002; Javalgi et al., 2004; Scupola et al., 2009), they have rarely focused on fundamental questions such as: what types of articles have been influential in e-service research? Does the e-service research field have different subfields, and what is the relationship, if any, among them? The purpose of this study is to answer the above-mentioned questions by using a bibliometric approach. The analysis, by identifying relevant concepts and theories that have emerged in the field of e-service, may help interested researchers identify how they can contribute to the field of e-service – by adding and enriching emerging groups or acting as bridges across groups.
An Australian University Implementing E-Learning System
Authors: Sandhu Kamaljeet
Published: April 2012

User learning experience may be considered as one of the prominent factors shaping the adoption of web-based systems. Web-based learners interfacing with large amounts of information the rationale is to deduce the effect in the current web-based task environment. Understanding Web-based learner perception on the basis of the prior experience with information may provide insights into what constitutes in driving those perceptions and their effect in the current and future web-based learning process. The paper demonstrates theoretical context of user learning experience with information and proceeds in an attempt to distinguish factors in using web-based systems.
Emerging Markets and Digital Economy
Authors: Al-Khouri Ali M.
Published: April 2012

This article provides an overview of the literature surrounding emerging markets and the global paradigm shift taking place towards the development of digital economies. It provides a review of recent practices in the government sector. The article promotes the concept of developing a government based identity management infrastructure to support the progress en route for building the digital economy. In light of increasing information security threats in today’s interconnected world, the article emphasizes that only through identification and authentication capabilities, emerging markets can maintain sustainability.
Hajj Crowd Tracking System in a Pervasive Environment
Authors: Mantoro Teddy , Ayu Media , Mahmud Murni
Published: April 2012

Hajj is a huge congregation of Muslims from all over the world which happens annually in Makkah, Kingdom of Saudi Arabia (KSA). It is one of the pillars of Islam and every able Muslim must perform this act at least once in their lifetime. Many challenges are faced by the organizers as well as the pilgrims during this massive religious gathering. Cases of missing Hajj pilgrims are not uncommon and although several tracking and navigation devices have been introduced, there is still a need for a better solution in overcoming the issue. There are several factors that prevent widespread use of the system, such as the operational costs, availability of the connections and the use in uncommon platform. This paper proposes a framework for tracking Hajj pilgrims in a crowded pervasive environment using a system called HajjLocator. A discussion on the prototype of HajjLocator, as a system to track and monitor pilgrims while performing Hajj and to save lives, with an SOS mechanism, is also presented in this paper.
What is Technology?
Authors: Woodhead Roy
Published: April 2012

This paper, a personal view rather than an official HP view, questions what counts as technology given that it has played a significant role throughout human history. It uses a non-technological ‘human’ situation as a datum point from which technology is explored in terms of how people become subservient to it. It briefly surveys the literature before differentiating between particular instances of technology, such as an airplane, and the collective effect of all technologies. These are termed a “Technology-Instance” and the “Technology-Collective”. The collective effect of all Technology-Instances produces emergent properties at the Technology-Collective layer, leading technology to create needs in the form of feedback loops that stimulate the development of more technology. Interdependencies between technological needs create choices available to humans and brings in to question whether notions of being free thinkers is constrained. Technology controls people because people do not acknowledge a systemic effect at the Technology-Collective level of abstract. People’s attention focuses on the control of a Technology-Instance but not on the Technology-Collective and the biases that influence people’s ways of characterising options. The author concludes by arguing people can, and need to, control the Technology-Collective.
The Research of Linear Rotation-Axis Control Machining CNC Rotary Cam Surface Transformation
Authors: Ding Feng Qin , Yu Yi , Miao Zhi Yi
Published: April 2012

General CNC milling machine for special transformation in the middle and low numerical control system of internal control software does not change under the premise of achieving the original system does not have the linear movement and rotary movement of the operating linkage function. The numerical control system of linear movement into rotary movement of the operation, and expansion of two straight line linkage CNC system functions, cleverly converted to a straight line movement control of a rotary movement of the linkage, thereby achieving the surface of the cylinder rotating cam track surface CNC machining. CNC Milling through the difficult parts of the application examples to explain the design principles of transformation CNC milling machine, design approach,As well as the design parameters in the programming of data conversion. And data conversion processing errors resulting from the measures and the elimination of error analysis.
Development of KM-Based Multi-Criteria Decision-Making Method for Evaluation of 4-Axis CNC Machine Tool
Authors: Tsai Jo Peng , Cheng Hsin Yu , Wu Jen Her , Lee Rong Shean
Published: April 2012

Facing the increasing competitive environment of globalization, companies are forced to make careful decisions so as to get the competitive advantage. The analytic hierarchy process (AHP) method has be proposed and popularly applied in many disciplines over three decades. In the past, many scholars also developed various improved methods such as Delphi AHP , fuzzy AHP, or Analytic Network Process (ANP) to enhance the decision quality. However, all the current AHP related methods have no function to provide enough reference information and a friendly environment to support the decision makers. Recently, Knowledge Management (KM) has attracted a great deal of interest in industry and academy. Therefore, in this paper, we proposed a KM-based AHP decision-making method to provide the questionnaire designer a guideline or reference and developed a decision-support web questionnaire system based on the knowledge chain model. A case study of selecting a 4-axis machine tool was illustrated the implementation and applicability of this method, a mold manufacturing company was invited as the survey objective. The method proposed in this research provides a different research direction and it is general in form to be applied for the other multi-criteria decision making cases.
The Design of 8-Link Mechanism of Horse Leg-Like Moving
Authors: Tso Pei Lum , Lu Chung Yi
Published: April 2012

In this thesis, an 8-link mechanism was design to simulate a real horse running leg. The 8-link type has been decided first, than the solution plane method has been used to the linkage synthesis. A computer software has been developed to solve the given loop equations. This software can give the profile of the mechanism and the information of the link length and the moving curve of the decided touch-ground point quickly. Several 8-link mechanisms were presented according to the designers choice. The results show that this method as well as software is able to develop complicate 8-link mechanism freely and correctly.
Research on Automatic Design of Extendable TrussBased on CAD Software
Authors: Sun Ru , Wang Chun Jie , Liu Peng
Published: April 2012

This paper provides a method of automatic design for extendable truss based on CAD software. The method mainly consists of parametrical design, automatic assembly, interference checking and extraction of model properties. With Visual C + + as programming language, secondary development was done on automatic assembly and other related modules of CAD software, which can achieve parametrically automatic assembly, interference checking and automatically extracting properties of extendable truss model. Thus, this method can guide the design staff performing program design, improve the correctness and accuracy of design, shorten the design cycle of extendable truss and also has reference value on rapid design and development for other products.
Effect of Friction on Dynamics of Gear System Featuring Confluence Transmission
Authors: Gao Hao Dong , Zhang Yi Du , Gao Xiang Sheng
Published: April 2012

In order to investigate the effect of friction on gear system featuring confluence transmission, a non-linear dynamic model of three-gear system having two gear pairs was built. The influence of gear systems dynamic characteristics caused by changing of friction coefcient was researched. With the changing of friction coefcient, left-right gear pairs show dynamic behavior with coexist of same periodic motion, coexist of different periodic motion and chaos. With the increase of friction coefcient, the jump phenomenon of amplitude occurred, the impact of gear system became larger.
QFD&DFMA Application on an Oil/Water Separation Product
Authors: Lu Ti , Zhang Yi Du
Published: April 2012

When oil fields become old, the proportion of water in crude oil will get higher and higher. Using a traditional bulk separator to extract the water from crude oil has many disadvantages: e.g. high pressure loss, low separation speed, heavy equipment and sensitive to direction. Caltec Ltd. has developed Wx-12, an innovative separator for the oil and gas industry. The device has been tested on offshore platforms and has shown high performance. Currently however, the manufacturing cost of the device is too high making it unlikely to be accepted by market. This project first used QFD to transform the user requirements of Wx-12 into engineering specifications. Then DFA & DFM methods were applied to Wx-12 in order to make it compact and reduce the manufacturing cost. An alternative design for Wx-12 unit was generated according to the results from QFD, DFA and DFM. Alternative materials were also considered to support the alternative designs. Finally alternative designs and alternative materials were verified with the engineers from Caltec Ltd..
The Application of Thermoelectric Cooling Module in the Vehicle's Braking System
Authors: Hsueh M.H.
Published: April 2012

The research is presented a kind of cooling device for a vehicles brake cooling system, which comprises a thermoelectric cooling (TEC) chip and a heat exchange system. The disc-brake and drum-brake systems are discussed in the research. After inputting electric power, the TEC chip provides one cooling surface which is stick on the brake system and absorbs the heat from the brake pads or shoes. The other surface releases heat which is absorbed by a recycle water-cooling system to discharge the heat by water-cooled radiator to the surrounding. It decreased the working temperature of the brake system about 30% at most after using this cooling device and increased the braking force about 30% at least. There is a temperature control device for the device which can start the TEC chip when the temperature of the brake pads or shoes exceeded 50, which is the lowest temperature that the brake pads or shoes can maintain the most performance of the braking force. The device can efficiently keep the braking force when the driver uses the brake to reduce the vehicles speed for a long time and provide the safety for the driver.
Research on Machining Method of Complex Surface Face Gears
Authors: Wang Yan Zhong , Hou Liang Wei , Liu Yan Qiang , Shen Rong , Wu Can Hui , Ge Hong Xia , Zhang Zu Zhi , Zou Wu , Li Yuan
Published: April 2012

This paper describes the machining method of complex surface face gear used CNC machine tools and hob cutter, Based on surface characteristics and gear hob principle. A coordinate transformation process is explained in detail in the five axes CNC machining of complex parts. A CNC hob method is proposed about surface orthogonal gear. An experiment is done for validating the method.
Dynamic Modeling for the Impact of Compliant Legged Robot
Authors: Bi Shu Sheng , Zhou Xiao Dong , Zhang Li Ge
Published: April 2012

Compliant elements play an important role in running and hopping legged robots for improving their speed and energy efficiency. The dynamic model of the compliant legged robot was developed by taking into account the slipping, vibration and distributed compliance of the legs. The parameter variations of the system after impacts were researched for different dropping height and angles by numerical method. Meanwhile, the effectiveness of the model was verified through explicit dynamics analysis software. All these results will provide a theoretical guide for the energy efficiency analysis and mechanical design of the compliant legged robots.
Curvature Analysis of Conjugate Surfaces via a Tensor Approach
Authors: Wang Peng , Zhang Yi Du , Deng Jie
Published: April 2012

A novel invariant approach is proposed for derivation of curvature relationship between conjugate surfaces of line contact. Unlike other approaches found in the literature, tensor analysis is applied to the derivation process in which rigid-body motion is represented by rotation tensor and the local geometry of surface is expressed by curvature tensor, and the final result is given in a clear and compact form. An example of helical gear is provided to illustrate the application of the proposed approach.
Dynamic Modeling of Compliant Mechanisms Based on 2R Pseudo-Rigid-Body Model
Authors: Wang Wen Jing , Bi Shu Sheng , Zhang Li Ge
Published: April 2012

Compliant mechanism is a kind of new type mechanism and its analysis is very complex because flexible links often under large deflections which introduce geometry nonlinearities. A new model (2R PRBM) can simulate accurately both the deflection path and angle of the flexible link. A new dynamic model of compliant mechanism is developed using the 2R PRBM. The dynamic equation of planar compliant mechanism is derived. The dynamic analysis on the natural frequency of compliant mechanism is obtained in the example of a planar compliant parallel-guiding mechanism. The numerical results show the advantage of the proposed method for the dynamic analysis of compliant mechanisms.
Simulation on Static and Dynamic Characteristics of Servovalve
Authors: Li Meng , Pan Xu Dong , Wang Guang Lin , Song Bo Yan
Published: April 2012

In this paper, we build a simulation model of the two stage flapper-nozzle electro hydraulic servovalve with the hydraulic component design libraries and the AMESet secondary development of modeling in AMESim simulation environment. By adjusting the parameters of the model, the performance of the servovalve were analyzed. At the same time, we can get the characteristic curve of the servovalve. These characteristic curves can describe the static and dynamic characteristics of the valve which can greatly guide for the study of the servovalve.
Position Error Research of Four-Legged Walking Robot's Swing Leg
Authors: Wang Liang Wen , Chen Wei Hong , Wang Cai Dong
Published: April 2012

In the moving process of four-legged walking robot, the robot uses the random 3 foots to support its body, and the rest 1 foot to swing. This process is carried on alternately to complete the robot moved forward. If the robot's foothold position, the independent drive joint variables and the length of leg linkage are inaccurate, the robot's swing leg would deviate from the desired position, which led to the robot will deviate from the target track. The robot's swing leg trajectory is analyzed in this paper. On this basis, the swing leg trajectory accuracy is discussed under the condition that the errors of the robot's foothold position, drive joint variables and leg's linkage length are given. The analysis process is illustrated by an example. The error analysis has significant meaning for four-legged walking robot control .
Structure Analysis and Design of Coal Mine Refuge Chamber
Authors: Zhang Hai , Li Sen , Cao Shu Juan
Published: April 2012

Removable steel refuge chamber is a very important device for lifesaving in coal mine disasters, such as fire, gas explosion, roof fall, and so on. So the chamber body should have good stiffness, strength, and tightness under disaster conditions. The stiffener structure in refuge chamber body has been investigated with FEM, and a kind of design was suggested.
The Effects of Bony Structure Simplification Methods on the Biomechanics of Tibiofemoral Joint in Series of Flexion Angles
Authors: Zheng Hai Dong , Huang Rong Ying , Zheng Hong Guang , Guo Yun Fei
Published: April 2012

To investigate the effects of bony structure simplification methods on the biomechanics of tibiofemoral joint under compression and torsion effects in series of flexion angles, the MRI images of the normal human knee at flexion angles of 0°/25°/60°/80° were developed through SONATA MAESTRO 1.5T, then through the technology of threshold segmentation and registration assembly, bone tissue distinguished models and single material models were built based on these images. The results show that: (1) at the flexion angles of 0°/60°/80°, the maximum equivalent stress on femur and femoral cartilage significantly were slightly higher than single material models, only at 25 °, the maximum equivalent stress of the femoral cartilage in single material model was obviously larger; (2) difference of maximum equivalent stress on tibia and tibial cartilage between two kinds of models was not significant, and stress increased with the increase of flexion angle, only at 80 °, the stress on tibia of bone tissue distinguished models reduced; (3) The skeletal load was borne mainly by the cortical bone.
Dynamic Simulation of the Six Axis Machining Robot for Trajectory Planning in CATIA-LMS
Authors: Luo Yi , Gibaru Olivier , Olabi Adel
Published: April 2012

Nowadays six axis machining robots are widely used in many fields of industry. Compared to machine tools, industrial robots offer a cheaper yet more flexible alternative to the machine-tools in the cleaning and pre-machining applications of aluminum castings. But the low stiffness has limited the application of industrial robots to the machining tasks with very low precision requirement. This paper presents a practical approach to improve the robot-machining accuracy by developing an off line simulation tool. Firstly we will complete the dynamic simulation of the 6-axis stiff model in CATIA-LMS for trajectory planning. Secondly we will set flexible joints and balancing system for the industry machining robot in LMS. Finally we will make some compare with the position trajectories generated by flexible joint and stiff joint, and then adjust the parameters under the references of the simulation result before the industry machining.
The Classification of Disposable Mechanical Elements
Authors: Li Yue Feng , Pan Xu Dong , Wang Guang Lin
Published: April 2012

Disposable mechanical elements with extremely short lives are widely used in the aerospace and defense fields. To reliably evaluate the life of disposable mechanical elements, many attentions were concentrated in the fatigue properties of disposable mechanical elements. According to the different meanings of static strength for metals, disposable mechanical elements are divided into two groups with different fatigue properties: extremely low cycle fatigue module for Type I with ultimate strength as design stress and low cycle fatigue module for Type II with yield strength as design stress. The Kuroda model and a cumulative damage model consisting of the Miners rule and the sequential law are used in the fatigue design process of the Type I. To the Type II, the Manson-Coffin model is suitable for conventional applications but more attempts are still conducted to further improve stress levels. The Type II with increasing load sequences are specially treated, since the cyclic yield strength of certain materials under pulsating stress closing to the yield strength increase with the deepening of fatigue damage. Consequently, under the increasing pulsating cyclic loading, the later load whose amplitude is higher than the initial yield strength will be permitted.
Dynamic Analysis of Extendible Support Structure Deployment
Authors: Song Shun Guang , Wang Chun Jie , Wang Han , Lin Qiu Hong
Published: April 2012

To study the dynamic behavior of the extendible support structure deployment, a digital simulation using the multibody system dynamics methodology is conducted. Floating frame of reference formulations are used to establish the flexible dynamics model, in which the deformation vector of each flexible part is modeled with the component mode synthesis technique based on the Craig-Bampton method. Modal truncation is implemented through modal participation factors to reduce the computational burden. Angular displacements results of antenna panels as well as those of truss rods are then obtained and show that all parts of the structure have reached accurate positions and keep stable after deployment as expected. Start torque of the driving motor is also acquired and proved acceptable according to the design requirements. Impact forces acting on the hinges at locking moment are finally extracted to evaluate performances of locking processes.
Experiment and Discussion on Ultrasonic Vibration-Assisted Single Point Diamond Turning of Die Steels
Authors: Xie Xiao Dan , Li Yong , Duong Cam Vinh , Al-Zahrani Ahmed
Published: April 2012

Traditionally, single point diamond turning (SPDT) can not process ferreous metals because of acute tool wear. Ultrasonic vibration-assisted cutting(UVC) provides a promising solution for the problem. In this paper, for the aim of directly obtaining mirror surface on die steels, UVC method was used combining with SPDT process. Experiments were carried out on an ultra precision turning machine, cutting parameters and vibration parameters were well-chosen, and two kind of feed rates, two kinds of prevailing die steels were experimented. Mirror surfaces were successfully achieved on face turning, with the best roughness of Ra16.6nm. And the surface roughness, surface texture and tool wear in machining process were discussed.
Influence of Cup Wheel Grinding and Etching Pretreatment on Residual Stress and Surface Topography for Coated Cemented Carbide Tools
Authors: Song Tie Jun , Zhou Zhi Xiong , Li Wei , Tang Ai Min
Published: April 2012

Cup wheel grinding and etching pretreatment are widely used in complex coated cemented carbide cutting tools machining process. The two processes determine different surface properties due to various mechanical and thermal loads in grinding and complex chemical reaction in etching pretreatment. In this paper, the effect of the grinding wheel speed, the grinding feed rate and the etching time with the Murakami and acid solution on the residual stress and surface topography of coated cemented carbide cutting tools are investigated. After each process, the samples are characterized by scanning electron microscopy and X-ray diffraction. It is found that the grinding wheel speed has a significant influence on residual stress measured in the WC phase. Etching by Murakami generated smooth surface, which partly removed the near-surface residual stress quickly but cannot eliminate.
Effects of Process Parameters on Surface Gloss in Rapid Heat Cycle Molding Process
Authors: Li Ji Quan , Chen Chuan , Jiang Shao Fei , Chai Guo Zhong , Lian Zhi Biao
Published: April 2012

process parameters; surface gloss; Rapid Heat Cycle Molding Abstract: Rapid Heat Cycle Molding is a novel injection molding, which may improve product surface quality effectively. In this paper, one-factor experimental design and Taguchi method were used and the influence of different process parameters (mold heating temperature, melt temperature, injection rate, injection pressure, and packing pressure) on surface gloss of injection product was studied. The results showed that temperature is the significant factor to the surface gloss. Mold heating temperature is principal factor in mold process parameters, while the melt temperature is the secondary factor and injection pressure is the least. The surface gloss increases with increasing mold heating temperature, melt temperature, injection rate through whole processing, while it increases to top then decreases with increasing injecting and packing pressure
The Acoustic Micro Integrated Detection Technique for Silicon Wafer Processing
Authors: Sun An Yu , Ju Bing Feng
Published: April 2012

This document presents an integrated detection method for the whole cycle of silicon wafer processing based on Scanning Acoustic Microscope (SAM). It can be used for thickness and chamfering measurement, surface and subsurface testing, internal defects detection and identification. A SAM system was designed for silicon processing and silicon-based devices fabrication. It has more favorable measuring accuracy and quantitative analysis ability than the traditional inspection equipments using for wafer process such as infrared detector.
Plasma Chemical Vaporization Machining of Silicon Carbide Wafer Using Flat-Bar Electrode with Multiple Gas Nozzles
Authors: Sano Yasuhisa , Aida Kohei , Nishikawa Hiroaki , Yamamura Kazuya , Matsuyama Satoshi , Yamauchi Kazuto
Published: April 2012

Silicon carbide (SiC) power devices have received much attention in recent years because they enable the fabrication of devices with a low power consumption. To reduce the on-resistance in vertical power transistors, backside thinning is required after device processing. However, it is difficult to thin a SiC wafer with a high removal rate by conventional mechanical machining because its high hardness and brittleness cause cracking and chipping during thinning. We have attempted to thin a SiC wafer by plasma chemical vaporization machining (PCVM), which is plasma etching using atmospheric-pressure plasma. In this paper, we describe a machining property using a newly developed flat-bar electrode with multiple gas nozzles for thinning a SiC wafer.
New Researches for Fabrication of Micro-Pin in Micro-ECM
Authors: Wang Ming Huan , Wang Tao , Peng Wei
Published: April 2012

Micro-electrode preparation is the key technology in micro-machining of micro- mechanics and micro-parts. In this research, the machining method of micro-pin using micro-electrochemical machining (micro-ECM) was proposed. The principle of micro-pin fabrication is introduced and the studies are focused on the effects of varies parameters on the shape of the micro-pin. The theoretic model between the shape of micro-pin and the parameters including power, voltage, duty ratio of pulse power, immerge depth of electrode is built up and then verified by experimentations. Experimental results denote that the micro-electrode with desirable shape and size could be prepared by controlling applied parameters. When the immersing depth is deeper, the pulse power, low voltage and duty ratio is proper selected. On the contrary, the DC power or pulse power with higher voltage and duty ratio should be applied. Finally, micro-pin with diameter of 5μm and 60μm long was fabricated when the DC power of 1.8V voltage and immersing depth of 1mm is applied.
Ultra-Wide Car Lens Optimization Based on Low-Tg Aspheric Glass
Authors: Zhu Yong Jian , Na Jing Xin , Sun Jian Feng , Yin Shao Hui
Published: April 2012

Car camera lens is widely used for the safety system of all kinds of vehicles. The car lens should have very wide field angle, strong ability to endure vibration and thermo-mechanical instability as well as erosion. According to these requirements, a new car lens is designed based on the aspheric glass lenses. The whole structure of car lens contains six separated glass lenses including two aspheric lenses. To reduce the cost, the aspheric lenses are made from low-Tg glass which is adaptable for mass production by glass molding press. The total track of lens is less than 30mm. For the enhancement of night vision, the F-number is set to be 2.4. The full FOV (field of view) of 160 is wide enough to capture all the dangerous information around the car. The imaging resolution is designed to be 3 Mega pixels. The designed result proves that the new car lens features high imaging quality. Its MTF (modulation transfer function) value is not less than 0.15 at the Nyquist frequency as for the field angle of 160. At the half Nyquist frequency, the MTF values of the most field angles are not less than 0.5. Therefore, the new lens could be used in the front of car to monitoring the dangerous cases around the corner.
Finite Element Analysis on Non-Isothermal Glass Molding
Authors: Zhu Ke Jun , Yin Shao Hui , Yu Jian Wu , Zhu Yong Jian , Jin Song , Wang Yu Fang , He Jian Jie
Published: April 2012

Glass molding is a high-volume fabrication method for producing optical components. Non-isothermal glass molding press (NGM) was proposed to fabricate optical glass, and its characteristics were studied by finite element method (FEM) simulation. The coupled thermo-mechanical analysis was carried out to analyze the key factors such as temperature distribution, stress distribution and strain distribution. The non-isothermal and isothermal glass molding (IGM) was studied, and optimal temperature match between glass and mold was obtained.
Study on Material Removal Rate of CMP 6H-SiC Crystal Substrate (0001) C Surface Based on Abrasive Alumina (Al2O3)
Authors: Su Jian Xiu , Du Jia Xi , Liu Xing Long , Liu Hai Na
Published: April 2012

SiC crystal substrate has been widely used in the area of microelectronics, photonics and new materials, such as semiconductor lighting, integrated circuits, and so on. In this paper, the influences of the polishing slurry composition, such as the pH value, the abrasive size and its concentration, the dispersant and the oxidants, the rotational speed of the polishing platen and the workpiece and the polishing pressure on the material removal rate (MRR) of SiC crystal substrate (0001) C surface based on the alumina abrasive in chemical mechanical polishing (CMP). This study results will provide the reference for developing the slurry, optimizing the process parameters and researching the material removal mechanism in CMP of SiC crystal substrate.
Research on Process Parameters Intellectual Decision Support System for High Efficiency and Precision CMP Function Ceramics
Authors: Hu Zi Hua , Gao Man Ke , Yuan Ju Long , Yang Xiang Jun
Published: April 2012

Based on the hybrid combination of case-based reasoning and BP-neural network, process parameters intellectual decision strategy of function ceramics with high efficiency and precision chemical mechanical polishing (CMP) was proposed in this paper firstly. And then, referring to the technical manuals, experiences of engineering workers and experimental data, the process parameters database for function ceramics in CMP has been built with Microsoft software Access. On the basis of the above efforts, the process parameters intellectual decision support system for high efficiency and precision CMP of function ceramics has been developed by applying PowerBuilder software, which can realize the process parameters optimization, the surface roughness prediction and process parameters intellectual decision. Examples show that the prediction results are coincident with the experiments well.
Experimental Study of Material Removal Rate for Rotary Curved Surface Workpieces of Si3N4 in Chemical-Mechanical Polishing Using Taguchi Technique
Authors: Wan Lin Lin , Deng Zhao Hui , Li Sheng Chao , Long Piao
Published: April 2012

By applying chemical-mechanical polishing (CMP) technique to high precision processing of rotary surface workpieces of silicon nitride (Si3N4) ceramic, a CMP experimental device was established on a numerical control (NC) jig grinder. The polyurethane wheel and nonwoven cloth wheel was adoped. The CeO2abrasive was applied to configure the water base polishing solution. Using Taguchi robust design method, through S/N ratios and analysis of variance, the influence of slurry concentration, polishing wheel speed and polishing wheel feed rate on material removal rate (MRR) were analyzed. With the increase of polishing wheel speed and polishing wheel feed rate, the MRR decreased. There was a balance concentration leading to the largest MRR. The best process parameters were selected: the slurry concentration of 20%, polishing wheel speed of 6000r/min, polishing wheel feed rate of 2.29mm/min, The result showed the descending order of selected process parameters impacting on MRR was polishing wheel speed, polishing wheel feed rate and slurry concentration.
Research on Tool Wear and Surface Characteristics in Ultrasonic Milling Carbon Fibre Reinforced Carbon Composite
Authors: Gao Guo Fu , Zhao Yan Yan , Ma Xing Hui
Published: April 2012

The experimental research on ultrasonic vibration assisted milling non-ablating carbon fibre reinforced carbon composite was carried out by employing uncoated tungsten carbide milling cutter, in order to reduce the machining cost and improve the surface quality of workpiece. According to the experimental results, the tool wear was reduced and the surface quality of milled carbon fibre reinforced carbon composite was improved. Compared to traditional milling method, the flank wear land was narrowed and it dominated by abrasive particles wear mechanism. The wear trace was even and wide, with width of 7-8μm; while the rake face was worn in the mode of adhesion wear mechanism. Most of carbon fibres were cut off directly and there were little fracture, pull-out and delamination; the matrix phase was removed nearly in hybrid of brittle and ductile regime and surface damage was small.
CAD/CAM System of Micro-WEDM for a Micro-Air Journal Bearing Fabrication
Authors: Zeng Zhao Qi , Wang Yu Kui , He Xiao Long , Wang Zhen Long
Published: April 2012

The fabrication of a micro air journal bearing for micro gas turbine engine is investigated based on CAD/CAE and CAM in this paper. Numerical simulation of the aerodynamic micro air bearing is conducted to investigate the bearing load capacity. Then, a removal analysis and contouring strategy of accurate micro-WEDM processing for the air bearing is conducted based on CAM postprocessor. The extended and trimmed tool path is adopted for micro-WEDM. The inner and outer diameter of the bearing is 1.068mm and 1.165mm, respectively. The radius of the bearing corner is 15.9µm, and the height is 53µm.The satisfactory workpiece shape illustrates that the CAD/CAM integrated system is accurate and useful in micro-structures machining.
Simulation on Hydraulic Performance of Two Kinds of Coring Diamond Bits with Different Crown
Authors: Chen Yan , Liu Zhi Yi , Duan Long Chen
Published: April 2012

The software CFDesign was used for the analysis of flow field simulation of two different kinds of drilling bit. The results showed that, if the waterway design of drilling bit was unreasonable, it could result in the following phenomenon: the local position of drilling bit could get severe erode of drilling fluid; the return of flow and eddy currents could be observed in the bottom of drilling well; negative pressure could be detected and might result in cavitation corrosion; the direction vector of flow field were diffused and resulted in cross flow. The waterway structure of arc-bottom bit was more reasonable comparing that of flat-bottom bit.
Path Optimization of the Drilling Hole Based on Genetic Algorithm
Authors: Chen Jia Ming , Guo Wei Gang
Published: April 2012

To improve the efficiency of holes drilling, the genetic algorithm was employed to optimum the air travel of holes drilling in this article. The implementation of genetic algorithm was described in detail, and the performance of the genetic algorithm was demonstrated using an example. Results showed that the optimization for holes drilling using genetic algorithm can improve the efficiency of drilling by reducing the cost of air travel.
Gasify Micro-Oil Ignition Technology Based on Level Set Methods
Authors: Wang Bei , Xie Yi , Xiong Jian Guo
Published: April 2012

In order to improve the Micro-oil ignition and low fuel load stable combustion in the thermal power system, the standard k-ε model is used in the analysis of flow field for studying the character of the mixture of coal particles, oil and gas mixture. The trajectories of two-phase flow are simulated by the Level Set Methods (LSM). The results describe the velocity distribution of the X-axis of the two-phase flow, concentration and track of coal particles, the thermal distribution of mixed fluid in the combustion chamber. It provides a theoretical basis for the further study of Micro-oil ignition technology
The Performances of Different Coated Carbide Drills when Drilling a Cast Nickel-Based Alloy
Authors: Xue C. , Chen W.Y.
Published: April 2012

The performances of different coated carbide drills when drilling cast GH625 nickel-based alloy were evaluated in terms of tool wear and cutting force. Wear pattern observation and cutting force measurement were conducted under different cutting conditions. It was found that the drill coated with TiAlN/TiN showed the best overall performance among all the drill types tested. This drill type gave the longest tool life in terms of number of holes partly due to the excellent wear resistance of TiAlN/TiN multilayer. Besides, the thrust force and torque produced with this drill type were lower, which could be attributed to its good adhesion resistance and chip-ejection ability.
Fabrication and Cutting Performance of CVD Diamond Coated Inserts with Different Coating Thickness in Dry Turning Aluminum Alloy
Authors: Zhang Jian Guo , Wang Liang , Shen Bin , Sun Fang Hong
Published: April 2012

CVD diamond coated inserts with different coating thickness are fabricated using hot filament chemical vapor deposition (HFCVD) method. Scanning electron microscope (SEM) and Raman spectroscopy are introduced to characterize the diamond films. The cutting performance of as-fabricated CVD diamond coated inserts is evaluated in dry turning aluminum alloy. The uncoated WC-Co tool is also adopted in the cutting tests for the sake of comparability. The testing results show that diamond coated tools exhibit much better cutting performance. Coating thickness affects the characteristics of diamond coated cutting tools, the thicker of coating, the more adhesive chips, but the better delamination resistant. The uncoated WC-Co tool suffers adhesive wear for the built-up edge (BUE) breaking.
Cutting Performance and Failure Mechanisms of Coated Carbide Tools in Face Milling Powder Metallurgy Nickel-Based Superalloy
Authors: Qiao Yang , Fu Xiu Li , Yang Xue Feng
Published: April 2012

Powder metallurgy (PM) nickel-based superalloy is regarded as one of the most important aerospace industry materials, which has been widely used in advanced turbo-engines. This work presents an orthogonal design experiments to study the cutting force and cutting temperature variations in the face milling of PM nickel-based superalloy with PVD coated carbide tools. Experimental results show that with the increase of feed rate and depth of cut, there is a growing tendency in cutting force, with the increase of cutting speed, cutting force decreases. Among the cutting parameters, feed rate has the greatest influence on cutting force, especially when cutting speed exceeds 60m/min. With the increase of all the cutting parameters, cutting temperature increases. However the cutting temperature increases slightly as the increasing of feed rate. Tool failure mechanisms in face milling of PM nickel-based superalloy are analyzed. It is shown that the breakage and spalling on the cutting edge are the most dominate failure mechanisms, which dominates the deterioration and final failure of the coated carbide tools.
Study on Dynamic Characteristics of a Hydrostatic and Hydrodynamic Journal Bearings for Small Diameter Grinding Spindle
Authors: Hou Zhi Quan , Xiong Wan Li , Yang Xue Bing , Yuan Ju Long
Published: April 2012

The dynamic characteristics of a hydrostatic and hydrodynamic journal bearing with two arrays of eight holes have been investigated theoretically by the three-dimensional Computational Fluid Dynamics (CFD) models with respect to equilibrium position. The various dynamic coefficients for design parameters, such as orifice diameter, length to diameter ratio, eccentricity ratio, supply pressure, and rotational speed, are analyzed systematically under the action of displacement disturbance and velocity disturbance which are considered by the User Definition Function (UDF) programs. Results show that the dynamic coefficients greatly affected by design parameters. The cross stiffness coefficients increase rapidly more than direct stiffness with an increase of length to diameter ratio and rotational speed. Conversely, the direct stiffness coefficients are larger than cross stiffness with an increase of supply pressure and eccentricity ratio. It indicates that the journal bearing with two arrays of eight holes is suitable for their applications to small diameter grinding spindle by the means of optimizing the operating parameters and the structural parameters in order to obtain a better dynamic characteristic.