bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Database for Checking Fixtures for Automotive Parts
Authors: Abdullah Zulkeflee , Imran Shahrul , Amran Mohd , Hasib Hazman , Muhammad Nor Salim , Jaafar Rosidah
Published: May 2015

The purpose of this study is to develop a database for checking fixtures for automotive parts. The parts used in the fixture checking process were automotive parts such as clamper, stand and toggle. The goal of this project is to implement a database of checking fixtures parts. The project started with identifying the current problems that were faced by the designer at a design department, in a support service for automotive industries. Idle time has been the major problem that designer have to faced. All the data and information related to this project has been sought and explored in the literature review. Catia software is used as the CAD software to construct three-dimensional models for the design of all the parts in the parts library. All the parts are organized in three different sizes which are determined by the size of car body panel. Referring to the result, new libraries were developed and created using the Catia software to aid designers in the checking fixture design process. The validation of the new libraries had been conducted with the company’s design engineer to test the effectiveness, usability and relevancy. In summary, this database and method can potentially accelerate the checking fixtures design process to be faster and more efficient.
Mechanical Properties of Oil Palm Empty Fruit Bunch Fibers-Cast Alloy Composite Using Three Point Bending Test
Authors: Hafizudin Mohammad , Sahroni Taufik Roni , Muhamad Mohd Razali , Farah Nurul , Kamal M.R.
Published: May 2015

This paper presents the mechanical properties of oil palm empty fruit bunch (OPEFB) fiber/epoxy resin reinforced cast LM6 (aluminum based) alloy composites. The metal matrix composite was fabricated by incorporating OPEFB/epoxy resin using mono filaments concept in the as cast LM6 alloys. Three different diameters (10, 12 and 14 mm) of the maximum force of metal matrix composite materials along with controlled sample (cast LM6 alloy + OPEFB/epoxy resin) were determined from three point bend testing. Test results showed that maximum force of mixture between OPEFB fibers composite and cast LM6 alloy for metal matrix composite are higher than that of cast LM6 alloy. Thus the utilization of OPEFB/epoxy composite as mono filaments in metal matrix composite can be significant in improving the strength of the cast LM6 alloy. Beside that increasing the diameter size of OPEFB/epoxy composite will reduce the weight of metal matrix composite (cast LM6 + OPEFB/epoxy composite).
Effects of Layer Thickness on the Microstructures of TiN/AlTiN Multilayer Coatings
Authors: Kadhim Kamil J. , Abd Rahman Nizam , Salleh Mohd Rizal , Mohd Zukee Khairul Izani
Published: May 2015

TiN/AlTiN multilayer coatings were deposited on tungsten carbide cutting tool by applying a direct current on a pulsed bias arc ion plating system. The effect of pulsed bias layer thickness on sample properties was investigated. The amount of grain size decreased with increasing layer thickness. The crystal structure of the coatings was determined using a D8 Advance Bruker X-ray diffractometer with CuKa (λ = 1.5405 Å) radiation. TiN/AlTiN multilayer coatings were crystallized with orientations in the (111), (200), (222), and (311) crystallographic planes, and the microstructure was enhanced with preferred orientation in the (111) plane. Compared with the substrate, all the specimens coated with TiN/AlTiN multilayer coatings exhibited better X-ray diffraction properties.
Effect of Different Coolant Medium on Warpage Deflection Using Moldflow Insight Analysis
Authors: Ali Mohd Amran , Salmah Siti , Abdullah Zulkeflee , Liew Pay Jun , Muhamad Mohd Razali , Izamshah Raja , Hadzley Mohd , Abdullah Abu , Marjom Zolkarnain
Published: May 2015

The effect of mould temperature on warpage using water and oil as coolant fluid was studied using flow software analysis. Mould temperature was controlled using two types of coolants; where cold mould was controlled by water and hot mould was controlled by oil. The simulation analysis was performed using flow software analysis Moldflow Plastics Insight (MPI). Taguchi method was used to design the planning matrix and to find the optimum levels of input variables. Then, to find the percentage contribution of input variables on output variables, analysis of variance (ANOVA) was used. It is found that mould temperature controlled by water shows less warpage analysis compared to oil. The minimum and maximum percentage of warpage analysis between cold mould and hot mould are 3.1% and 7.1% respectively. In addition, ANOVA analysis shows that the most significant parameters affected the warpage analysis for both moulds using oil and water are melt temperature (255°C) followed by mould temperature (water 15°C and oil 70°C) and cooling time (water 8s and oil 6s). Thus, it shows that coolant medium used in mould cooling system contributes the quality of plastic parts.
Effect of Nitrogen-to-Total Gas Flow Ratio on the Nanocomposite TiAlBN Coating
Authors: Rosli Zulkifli , Kwan Wai Loon , Rashid Mohd Warikh Abdul , Mohd Juoi Jariah , Nayan Nafarizal
Published: May 2015

A nanocomposite TiAlBN (n-TiAlBN) coating has been successfully deposited via RF magnetron sputtering by varying the nitrogen-to-total gas flow ratio (RN) at a substrate temperature of 300 °C. The coating was deposited on AISI 316 substrates using a single Ti-Al-BN hot-pressed target. The crystal phases, grain size and chemical composition of the coatings were measured using the glancing angle X-ray diffraction analysis (GAXRD) and X-ray photoelectron spectroscopy (XPS). The grains size of the n-TiAlBN coating was found to be within the range of 3.5 to 5.7 nm calculated using Scherrer’s formula. The n-TiAlBN coating reached a nitride saturated state at a higher RN (e.g >15%) with the amount of boron concentration to be around 9 at. %. Further, reducing the RN (e.g. 5%) has increased the boron concentration to 16.17 at. %. This paper shows that by carefully control the nitrogen-to-total gas flow ratio (RN) in the n-TiAlBN coating, it indeed gives a significant effect on its crystallographic structure, grain size, and chemical compositions.
Cyclic Voltammetry Analysis of Carbon Based Electrochemical Capacitor in Aqueous Electrolytes
Authors: Raja Seman Raja Noor Amalina , Munawar Rose Farahiyan , Abd Razak Jeeferie , Zulkapli Nor Najihah , Bistamam Mohd Shahril Amin , Talib Elyas , Tunku Kudin Tunku Ishak , Abdul Manaf Nor Syafira , Azam Mohd Asyadi
Published: May 2015

In this study, a mixture of activated carbon (AC) and graphene (G) was coated onto the stainless steel (SS) mesh to produce an electrode for the electrochemical capacitor (EC). Different materials, such as carbon nanotube (CNT) mixed with G, were also used in this experiment to compare the electrochemical properties of both electrodes. The electrochemical properties of the electrode were determined by using cyclic voltammetry (CV). The CV curves of the AC/G electrodes showed good capacitive behaviour, and the highest capacitance values obtained for AC/G and CNT/G electrodes in 1M H2SO4 at 1 mVs-1 were 13 Fg-1 and 4.34 Fg-1, respectively. Meanwhile, the highest capacitance values obtained in 6M KOH at 1 mVs-1 were 14 Fg-1 and 12.07 Fg-1 for AC/G and CNT/G electrodes, respectively.
Influence of Heat Treatment on Impact, Hardness and Fatigue Strength of 6061 Aluminium Alloy
Authors: Zaiedah Nasir Nurulhilmi , Mohd Daud Mohd Ahadlin , Bapokutty Omar , Talib bin Din Abdul , Selamat Mohd Zulkefli
Published: May 2015

This paper presents effects of heat treatment on toughness, hardness and fatigue strength of aluminum alloy 6061. The alloy specimens were heat treated in the furnace at different temperature levels and holding times; and then cooled in different media (water and oil). The mechanical properties such as hardness, impact and fatigue were examined using standard method. Result shows that mechanical properties of aluminum alloy can be improved by the heat treatment. It was found that through ageing processes at temperature 160 °C for one, three and five hours, decreased the hardness, while increased the toughness. The fatigue strength was decreased when the number of cycles increased. The fracture surfaces between specimens have a different appearance before and after heat treatment.
Binder Application in Durian Peels Briquette as a Solid Biofuel
Authors: Mitan Nona Merry Merpati , Azmi Akmal Hakim , Nur Fathiah M.N. , Se Sian Meng
Published: May 2015

A research on the application of calcium hydroxide as a binder for briquetting of durian peels has been performed. The main aim of the present research is to improve the structure of the briquette and to observe basic fuel properties of durian peels in the presence of calcium hydroxide. The carbonization of durian peels was carried out at 370 °C for one hour. Durian peels briquette was characterized by the proximate analysis, calorific value, compressive tests and Fourier transform infrared (FTIR). The briquette was formed by the cyclindricalmould and hydraulic press.The comparison of the compressive strength between durian peels briquette with and without calcium hydroxide as a binder was in the range of 11.41 MPa to 17.38 Mpa. The calorific value of the durian peels briquettevaries from 4968 to 5883 cal/g. The calorific value results show that the durian peels briquette has strong potential to be applied as solid biofuel.
Green Magnetic Composite Sheet from Durian Shell and Nano-Magnetite Particles
Authors: Shahril Mohd Khairul , Munawar Rose Farahiyan , Mohamed Muhd Hafez , Arif Afraha Baiti , Mohamad Noraiham , Abd Manaf Mohd Edeerozey , Abd Razak Jeeferie , Maulod Hairul Effendy Ab
Published: May 2015

Biomass-derived materials such as kenaf pulp and wood chips are a perfect candidate to produce magnetic paper. Furthermore, by using biomass waste, such as paddy straw, sugarcane, bagasse and durian shell, the cost of producing magnetic paper can be further reduced while giving added value to the waste. This paper investigates the potential of producing magnetic sheet from durian shell. Initially, durian shells were dried before undergoing the pulping process. The resulted sheet was then combined with magnetic particles, the nanomagnetite using either lumen loading or in-situ co-precipitation to produce a magnetic composite sheet. After being loaded with magnetic particles, the composite sheets were tested in terms of the homogeneity of the magnetic particles in the samples, degree of loading of the magnetic particles and the magnetic properties of the samples. Results obtained show a great success in producing the magnetic sheet from durian shell waste and nanomagnetite particles. It was also found that the lumen loading method gives better magnetic properties compared to the in-situ co-precipitation method.
Tensile Behavior of Polypropylene Reinforced with Comminutes Extracted from Out-of-Condition Aerospace Grade Carbon Fiber Prepreg Waste
Authors: Mohamad Noraiham , Abd Latiff Anisah , Drahman Mohamad Azrul , Shamsuri Siti Rahmah , Abdil Razak Jeeferie , Othman Intan Sharhida , Karjanto Juffrizal , Abdollah Mohd Fadzli , Ab Maulod Hairul Effendy
Published: May 2015

Carbon fiber reinforced thermoplastics are in demand for high performance composites, particularly for the aircraft industry. Waste disposal of carbon fiber in the form of off-cuts, out of life of prepreg and end-of-life components lead to the environmental pollution. This study focuses on the processing and characterization of carbon fiber prepreg comminutes reinforced polypropylene (PP) produced by melt compounding using an internal mixer. In this study, end-of-life carbon fiber prepreg were crushed into fine fibers and dried in oven at 220°C for one hour. It was divided into two types; (1) partially cured carbon fiber prepreg (c-CFP) and, (2) fully cured carbon fiber prepreg (c-CF). The composites were prepared by melt compounding in a Haake internal mixer at 180°C, 50 rpm for 10 minutes. Samples were tested for tensile properties (ASTM D638) and the morphology of fractured surface was observed using Scanning Electron Microscopy (SEM). Increasing carbon fiber in polypropylene was found to increase the Young’s modulus of the composites, but decreased the tensile strength. However, the tensile strength of composites with c-CFP were observed to surpass the neat PP at every loading level. Whereas for composites with c-CF the tensile strength was comparable to the neat PP only within the range of 3 – 5 wt.%.
Harnessing Buoyancy Force to Operate Mini Cost-Saving Water Treatment Plant for River Inlets
Authors: Kher V.K. , Talib bin Din Abdul , Tan Chee Fai
Published: May 2015

River pollution has been a global issue and the consequences of polluted rivers are significantly affecting human health and well-being. Meanwhile, water treatment plants (WTP) are often related to high energy cost. Nevertheless, there is an abundance of hydraulic energy stored in the flowing water, which can be converted into mechanical energy to operate the WTP. The focus of this paper is to describe an innovative method of harnessing buoyancy force to save the energy cost of commonly used motorized equipment in the conventional WTP. The benefit of this product is to create a green environment by utilizing a readily available hydraulic energy and restoring river water quality. This study has shown that a cost-saving water treatment plant operating based on buoyancy force is feasible. This product enables electricity cost to be minimized while treating river water at the same time.
Simulation-Assisted Ship Design Method for Maximizing Profit
Authors: Hiekata Kazuo , Moser Bryan
Published: May 2015

In ship building, the design objective is based on the performance, in terms of technological aspects such as fuel oil consumption rate, maximum speed or combination of those. The proposed method simulates the detailed cost breakdown based on the developed ship performance model and estimates the operational condition to maximize the profit in the market. The operation condition determines the service speeds at full and empty ship, and the market includes the oil price and the freight market. By considering only the technological indicators and assuming technological systems and the fluctuation of economic situations, the designs give different results. This manuscript illustrates how the proposed method works in a case to determine a propeller of a large tanker.
Human System Modeling Technique for Semiconductor Assembly and Test
Authors: Abdullah R. , Abd Rahman Md Nizam , Khalil Siti Nurhaida
Published: May 2015

Global competitions are putting pressure on the manufacturing companies to produce products cheaper and faster. Thus, manufacturing operations are urgently exploring methods to reduce cost through improved efficiency in managing the resources. In recent years, there has been growing interest to study human system due to the lack of focus as compared to other resources such as equipment and material. This paper presents the overview and evaluation of the various human issues affecting manufacturing system dynamics and performance. Furthermore, the gap in the current models will be discussed before presenting the development of a proposed model to study human system in semiconductor assembly and test.
Working Posture Assessment in a Small and Medium Industry (SMI): Automotive Repair Facility
Authors: Syed Mohamed M.S. , Basiri Muhammad Nur Hakam
Published: May 2015

In automotive repair facilities worldwide, technicians are exposed to various ergonomic risk factors such as excessive exertions, awkward and static postures. The exposure of several ergonomic risk factors can lead to work related musculoskeletal complaints. This study was set out to examine working postures encountered by automotive service technicians in a small medium industry automotive workshop. A total of 240 observations (n=240) were made, and five types of working positions were identified, namely the “Underneath Vehicle” (vehicle on floor),“Side of Vehicle” (vehicle on floor), “Under the Hood”, “Side of Vehicle” (vehicle on lift), and “Underneath Vehicle” (vehicle on lift). Two positions, which were the “Underneath Vehicle” (vehicle on floor), and the “Side of Vehicle” (vehicle on floor) recorded 69 and 60 occurrences respectively. These two positions posed a significant ergonomic injury risk since the upper limbs, shoulders, spinal flexion combined with static holding were present in those two positions.
The Effects of Roller Conveyor on Muscle Activity in Workpiece Loading on CNC Machining Centre: A Preliminary Study
Authors: Hafiz Zani M. , Isa Halim , Muhammad Syafiq S.M. , Rawaida O. , Nuradilah Z. , Fatihah Ros Ahmad
Published: May 2015

In the recent years, Advance Manufacturing Technology (AMT) has been widely used in manufacturing industry to increase manufacturing process capability. However, Computer Numerical Control (CNC) machine designs have only focused on its operational capability. The harmonious coordination between users and CNC machines is often neglected, which can contribute to hazardous working practices that can affect the health of users. Bending posture while loading the work piece to the machine can cause fatigue and discomfort to the users. Thus, the focus of this preliminary study is to analyse the effect of CNC machine work piece loading on muscle activity levels and to determine the effectiveness of roller conveyor in reducing muscle activity levels. Muscle activity has been analysed using surface electromyography (sEMG) technique. Erector spinae, biceps and trapezius muscles were concurrently measured during the work piece loading. Five male subjects (n=5) participated in the pre-intervention study and two subjects (n=2) in the post-intervention study (roller conveyor implementation) participated to test the effectiveness of the roller conveyor. Result pre-intervention study found that muscle activity level of biceps was the highest followed by trapezius and erector spinae. Based on the post-intervention study involving the roller conveyor, muscle activity of the erector spinae was reduced meanwhile the muscle activity of biceps and trapezius increased for both subjects.
Fatigue on Upper Quadrant Human Body: The Psychophysical Experience among Drivers
Authors: Fatihah Ros Ahmad , Seri Rahayu K. , Bani Hashim Ahmad Yusairi , Nuradilah Z. , Rawaida O. , Hafiz Zani M.
Published: May 2015

Upper body discomfort has become one of the issues to drivers nowadays. In this modern era, majority of Malaysian workers drive to work daily. This paper aims to find the most uncomfortable upper body part, as well as the effect of time, body mass index (BMI) and length of arm towards upper body discomfort for drivers. Sixteen volunteers were requested to complete the questionnaire soon after they completed driving the car simulator for three duration of times (30 minutes, 60 minutes and 90 minutes). Time is proven to be the main factor affecting the upper body comfort level, with the upper arm and lower arm being the most affected part during driving, [F(2,237) =14.37, p<0.01] compared to BMI and length of arm. It can be concluded that the upper body discomfort can be caused by driving for a long time. Nevertheless, the BMI and length of arm is not the issue for upper body discomfort.
Application of Quality Function Deployment to Design a Liquefied Petroleum Gas Trolley
Authors: Sultan Al Amin Mohamed , Isa Halim , Febrian Idral , Taufik Taufik , Nuradilah Z. , Nor A.M.
Published: May 2015

In Malaysia, the liquefied petroleum gas (LPG) is widely used for domestic purposes. The delivery men who are in charge of delivering the LPG cylinders to the customers are exposed to the ergonomic risk factors associated with excessive force due to the heavy steel cylinders. There are devices used to assist the delivery task, however, the devices are not efficient to be used in non-elevated apartments. Due to this reason, this study aims to design an LPG cylinder trolley. Quality Function Deployment was integrated to design the LPG cylinder trolley, so that it can fulfill the delivery man's requirements, thus, an effective device to assist the delivery task is produced. Based on the findings, it can be concluded that the integration of QFD is an effective solution in designing an effective LPG cylinder trolley.
Investigation of Cutting Parameter and Machine Tool Vibration Effects Using Regression Analysis to Enhance Part Dimensional Accuracy
Authors: Rahman M.A. , Md Sadan Nur Atiqah , Minhat Mohammad , Isa Halim , Baharudin Abu Bakar
Published: May 2015

Dimensional accuracy plays important criteria in producing high quality machined parts. This is a big challenge to manufacturers of precision components to produce good quality parts with minimum manufacturing error. The focus of this paper is to study the influence of the machine tool rigidity and cutting parameters on dimensional accuracy in turning operation. A method was prepared for identifying the factors effecting dimensional accuracy in a turning process. Experimental setup involved computerized numerical control (CNC) lathe machine, with VBMT 160404 carbide insert and mild steel, as cutting tool and workpiece respectively. The statistical analysis was used for analyzing and determining the accuracy of experimental data through Minitab statistical software. The regressions model was developed. The developed regression model could be used to predict the dimensional precision of the parts based on machine tool vibration and machining parameters during turning process. This is the aspect to be seriously considered and be applied in attaining sustainable machine tool development during design and development stage and its usage. This finding provides useful guidelines for manufacturers to produce high quality machined parts at minimum manufacturing cost. It was found that the cutting speed, feed rate, final part length, vibration x and vibration z have significant effects on dimensional accuracy of the machined parts.
Impact of Cross-Section and Size on Vibration of Silicon Nanowires
Authors: Zhang Peng , Chen Hong Bo , Yu Hong
Published: May 2015

In this article, impact of cross-section and size on vibration of silicon nanowires is simulated by the molecular dynamics method based on molecular dynamics software Material Studio. The comparison of fundamental frequencies of the silicon nanowires with triangle, diamond, and hexagon cross sections is carried out. The orientations of these silicon nanowires are all in <111> direction. Then we change the length and the width of silicon nanowires to investigate the impact of size on vibration of silicon nanowires. The results show that with the influence of surface effect, the vibration frequency of silicon nanowires strongly depends on cross-section and size.
Growth and Magnetic Properties of Three-Dimensional Firtree-Like Cobalt Microcrystals with Hierarchical Dendritic Superstructures
Authors: Yang Xi , Fu Zhi Bing , Yuan Lei , Wang Chao Yang , Chen Qian Wang
Published: May 2015

Novel ordered three-dimensional (3D) firtree-like hexagonal cobalt microcrystals with hierarchical dendritic superstructures have been obtained by using cobalt bis (4-pyridine carboxylate) tetrahydrate as the precursor of Co. The 3D dendrite has a main axis and the leaves arrange layer by layer in parallel along the axis, which exhibit the radiate hexagonal arrangement from the axis in a layer. The main axis of the dendrite grows along the [001] direction of hexagonal Co and the leaves grow parallel to the (001) plane. The hysteresis loop of the sample shows a ferromagnetic behavior with the saturation magnetization of 134.0 emu/g and the coercivity of 184.9 Oe. It is noted that the coercivity is relatively low compared with that of the cobalt dendritic crystallites reported previously, which may result from the lower total morphology anisotropy of our sample.
Design of Micromachining System Based on Nanosecond Pulsed Laser
Authors: Xu Dong , Yao Yao , Fu Xing , Wang Chao
Published: May 2015

In recent years, pulsed laser processing technology is widely used in MEMS device manufacturing, aerospace technology, precision instrument manufacturing and circuit board processing. According to the characteristics of nanosecond laser, this paper designs a novel nanosecond pulsed laser micromachining system with PMAC card as its core unit. The system can achieve automation control of laser parameters and movement pattern of motion system by software, which can easily realize automatic processing of point, line, and plane structure in micron scale. In this paper, several groups of experiments are taken to test the reliability and accuracy of the machining system and find the group to obtain the best processing result.
Design and Simulation of MEMS Mirror Based 3D Shape Measurement System
Authors: Zhang Chi
Published: May 2015

A 3D shape measurement system based on a laser rangefinder and a two-dimensional MEMS mirror is presented in this paper. According to the requirement of surface profile measurement, the 3D shape measurement system is mainly composed of a laser module, a two-dimensional MEMS mirror, a ranging module, an orientation module and an image composition module. Based on the MEMS scanning technology and phase shift ranging method, the surface profile of the target can be acquired by the measurement system. For the coupled scanning mode, the scanning pattern is simulated in Lissajous figure and the condition of covering all the field of view is analyzed. The simulation results show that the 3D shape measurement system based on the laser rangefinder and the two-dimensional MEMS mirror can realize the measurement the surface profile of the target in all the field of view.
Frequency Characteristics Research for the Negative Resistance Oscillations Phenomenon of a Silicon Magnetic Sensitivity Transistor
Authors: Zhao Xiao Feng , Li Yi Fan , Lv Mei Wei , Wen Dian Zhong , Zhang Hong Quan
Published: May 2015

A silicon magnetic sensitivity transistor (SMST) with negative resistance oscillations phenomenon is presented in this paper, which is constituted by emitter (E), base (B) and collector (C). The SMST chip is fabricated on <100> orientation high resistivity C-type silicon cup by using MEMS technology. Experiment results show, when external magnetic fieldB=0 T, base injection currentIbis the scope of 1.5mA to 1.7mA andVCEis greater than 4.0V, the collector currentIcappears negative resistance oscillation phenomenon, the oscillation frequency will increase with the increase of theVCE.Icchanges with external magnetic fieldB, whereVCEandIbare constant. With the condition of theIb=1.5 mA andVCE=9.0 V, the oscillation frequency ofB=0 mTand B=-150 mT are 5.88 kHz and 7.60 kHz, respectively.
Fabrication of a Pendulous Resonant Micro-Machined Biosensor for Direct Liquid Detection
Authors: Huang Gang , Li Yu Xin , Qian Li , Li Qi
Published: May 2015

This paper presents a pendulous resonant MEMS biosensor for liquid detection based on SOI-MEMS technology. The biosensor consists of two electromagnetically driven and sensed resonant paddles working in the torsional mode. The differential output consisted by the two paddles provides the sensor reading. 1um thick SiNx is deposited on the electrodes by plasma enhanced chemical vapor deposition (PECVD), making the biosensor capable of working in liquid directly. In device fabrication, SOI-MEMS fabrication processes were utilized, where a new modified buffered hydrofluoric acid (BHF) solution was used to remove the buried oxide layer and release the paddles. High-current drive circuit and energy compensation circuit are designed to improve the Q-factor of the paddle in liquid. Experimental experiments show that the biosensor can distinguish the density of some liquid effectively．
Analysis and Simulation of a Planar Microelectrode Structure for Dielectrophoretic Manipulation of a Single Cell and Cell Cluster
Authors: Chen Ping , Ma Xue Liang , Zhang Hua , Han Mei Jie , Wang Yong Cun , Li Bin Bin , Zhu Hai Xin
Published: May 2015

In this paper, we proposed a four-electrode microdevice for precise isolating and trapping of a single cell using negative dielectrophoresis (nDEP) forces. To generate appropriate nDEP forces, sinusoidal alternating currents (AC) signals with various phase shifting were applied to the microelectrodes, and the finite element analysis (FEA) techniques were used to analyze the resulted electric field distribution. The simulation results implied that effective trapping and rotation forces can be realized by the proposed device structure under specific excitation condition. The geometry effect on the electric field distributions of electrodes was further studied in details. For the electrodes with 50 μm width, the maximum value of the gradient of the squared field strength could reach 106V2/m3, which is higher than that for electrodes with 20 μm width. The influences of applied voltage to electric field gradient were also simulated and the result shows that the dielectrophoresis (DEP) force increased significantly with the magnitude of applied voltage. These preliminary results may provide useful insight and design guidelines for the future DEP microstructure design and fabrication.
Synthesis of Silica Modified Large-Sized Hydroxyapatite Whiskers by a Hydrothermal Co-Precipitation Method
Authors: Yin Yan Ting , Chen Qing Hua , Yan Ting Ting , Chen Qing Hua
Published: May 2015

The objective of this study was to develop a novel silica modified large-sized hydroxyapatite whiskers with improved properties for use in bone repair applications. Large-sized whiskers with a mean length of 250μm were obtained by a hydrothermal co-precipitation method at 150°C, 7.5Mpa in high-pressure reactor. Silica modified hydroxyapatite whiskers were prepared by dissolving TEOS in ethanol solution, then sintering with hydroxyapatite. The compositional and morphological properties of prepared whiskers were studied by means of x-ray diffraction (XRD), Fouier transform infrared (FT-IR), scanning electron microscopy (SEM). The results indicated the evidence of nanosilicon dioxide particles on the surface of HAP whiskers. The size of nanosilicon dioxide particles depends on dropping and stirring rate. Hence, this new type of silica modified large-sized hydroxyapatite whiskers is a valuable candidate for biomedical applications.Key words: hydroxyapatite, hydrothermal co-precipitation, surface modified, whiskers
Flow Field Analysis for Plant Vessel and Bionic Structural Microfluidic Chip
Authors: Zheng Chong , Guo Cui Yan , Xue Jing Wei , Liu Shi Bing , Chen Tao
Published: May 2015

Microfluidic chips have been widely used in various of areas, such as biology, chemistry, medical science and so on. As one of the key techniques of microfluidic chips, the technique of micro driven of the water has been studied by experts all around the world for years. Of all kinds of the driven methods, the power costed by bionic driven is lowest. Moreover, as xylem is the main channel to transport the water in a tree, the mechanism of water transportation has been always an important issue in the study of physiological plant ecology. In this paper, the models of a single vessel element with different pit numbers (5 pits, 10 pits and 20 pits) or diameters(4µm and 7µm) were established according to the xylem and the pits’ structure. The 3-dimensional flow distribution was analyzed by ANSYS 12.0 calculating by realizable κ-ε algorithm. The pressure distribution contours and the velocity distribution contours of a single vessel element could be obtained after calculated by the software. According to the results, the flow field in a single vessel element of the xylem was studied. In addition, the influence of pits on the pressure and velocity were analyzed. The results showed that the influence on pressure and velocity is less when the diameter is smaller. As the number of pits on the vessel increased, the influence on the distribution of pressure and velocity is greater. Based on the result of numerical simulation of vessel element, a bionic structural microfluidic chip was designed and then analyzed by ANSYS 12.0.
Preparation of Strongly Hydrophobic Film with Large Area and Flexibility Based on Micro Fabrication
Authors: Zeng Yi Bo , Wang Ting Ting , Wang Jian Yan , Guo Hang
Published: May 2015

In order to gain strongly hydrophobic film with large area and flexibility conveniently and effectively, how to prepare film with combination of technologies including micro fabrication, chemical grafting and micro molding is discussed. Firstly, micro channel arrays that the width is 5μm on the silicon wafer are prepared by micro fabrication. Then after spraying PVDF (Polyvinylidene Fluoride) lotion and pouring PDMS (Polydimethylsiloxane) glue solution onto the silicon wafer as the mould successively, the mixture need to be precured, which constructs rough structures in micro and nanoscale on the low surface energy film. Finally chemical grafting for film is carried out under the condition of O2 and 130°C so that the modification layer easy to adhesive on the boundary between PVDF and PDMS can be formed. Through the above technical routes, the strongly hydrophobic film that the general contact angle exceeds above 145o, the area is 180mm×64mm, the thickness is 0.9mm and the composite layer is firmly combined is gained. Compared to other hydrophobic materials the film is available in large area and has an advantage of flexibility. Meanwhile, the way that the film prepared by micro molding and in virtue of the silicon wafer with micro channel arrays as the mould contributes to large scale production.
Size Effect of Piezoelectricity in ZnO Nanowires: A First-Principles Study
Authors: Qin Chuan Qion , Gu You Song , Sun Xu , Li Chen , Zhang Yue
Published: May 2015

Piezoelectric properties of ZnO nanowires orientated along [0001] are investigated via density functional theory (DFT). A new method to calculate the volume of nanowires was proposed, which is crucial to the value of piezoelectric coefficients. Results show that the axial effective piezoelectric coefficients are 29.99 Cm-2, 25.93 Cm-2, 22.82 Cm-2 for ZnO nanowires with diameters of about 0.6 nm, 1.2 nm, 1.8 nm, which are considerably larger than that of the bulk (20.19Cm-2). It is found that the change in volume during the strain played a dominated role in size effects. This work helps to gain a deeper understanding of the piezoelectric size effects in ZnO nanowires.
The Simulation and Analysis of Current Crowding and Joule Heat in Flip Chip Solder Bumps
Authors: Liu Pei Sheng , Yang Long Long , Hang Jin Xin , Lu Ying
Published: May 2015

Electro-migration has become a critical reliability issue for high density solder joints in flip chip technology, especially for current crowding and joule heat. Electro-migration force and mean time to failure of flip chip are introduced in this paper. This study employs two-dimensional simulation to investigate the distribution of current density and Joule heating in the flip chip joint. It is found that current crowding and Joule heat effect are very serious in the solder bump. The Joule heat may play important role in the void formation and thermo-migration in solder bump. And the factors that impact the distribution of current density and Joule heat are studied. The results show that the thickness of Al and UBM has great influence on the distribution of current density and Joule heat.
Nanopore in C-S-H Gel Stability Analysis of Hardened Cement Pastes
Authors: Wu Lang , Xiong Na , Yu Fang Yan
Published: May 2015

Based on capillary tension, surface free energy and elasticity theory, a collapse model of nanopore in C-S-H gel was created in hardened cement pastes. The stability of pore was analyzed by Gibbs free energy theory. The results show that, the capillary is more stable while the capillary is grater and rounder in the case of the aperture changing in the nanometer scope. When the aperture is changing in the scope of micrometer, the collapse possibility of the capillary is tiny. If the capillary size is fixed, the capillary is more stable while the elastic modulus of hydrated products is higher.
Micro Laser Joining between Dissimilar Materials of 200μm Thick TiNi Alloy and Stainless Steel and the Joint’s Electrochemical Behavior
Authors: Chen Yu Hua , Xie Ji Lin , Gong Wei Huai
Published: May 2015

Dissimilar materials between TiNi shape memory alloy (SMA) and stainless steel of 200μm mm thick were butt welded by micro impulse laser and the electrochemical behavior of the weld joints was studied. The results show that the crack sensitivity of the welded joint is very high and good joining between TiNi SMA and stainless steel can be realized with pure Ni wire as filler material presented between TiNi SMA and stainless steel. The tensile strength of the welded joint with pure Ni wire as filler material is 580MPa. The electrochemical tests of the welded joints in different concentrations of NaCl solutions and different pH value solutions show that, the maximum of the corrosion potential Ecorr in the three typical corrosion systems (0.9%NaCl, pH=7.3; 3.5%NaCl, pH=7.3; 0.9%NaCl, pH=4) is the weld seam, which indicates that the corrosion tendency of the weld is smaller than that of TiNi alloy and stainless steel in the three corrosion systems. The pitting corrosion potential of TiNi alloy, stainless steel and the weld gradually decreased with the increase of Cl-concentration; the pitting corrosion potential decreased with the increase of H+ concentration, while TiNi alloy decreased faster than that of the weld and stainless steel, the surface stability of TiNi alloy is low when pH value dropped below 7.
Electrokinetic Research on the Dispersion Behavior of Nano-Ceria Particles in Concentrated Suspensions
Authors: Gao Wei , Wei Qi Long , Ding Ling , Li Xiao Yuan , Wang Chao , Tang Guang Ping , He Jian Guo
Published: May 2015

A multi-scale method was developed, which utilized intrinsic relationships among zeta potential of particles, rheological properties of suspensions and particle size distribution (PSD), to analyze dispersion behavior of nanoparticles in concentrated suspensions. It was found that PSD of a kind of nanoceria particles by dynamic light scattering (DLS) method in solution A with concentration 5 wt% accorded well with that by direct TEM analysis, which meant the particles had been dispersed well. However, there had a significant difference when the concentration was increased to 20 wt%. When particles concentration increased from 5 wt% to 20 wt%, zeta potential in solution A changed from-150 mV to-100 mV, while zeta potential in solution B changed from-35mV to-45 mV. Variations of zeta potential of particles accorded well with rheological properties of suspensions too, from phenomenological models. When the suspensions composed by solution A and the nanoparticles with concentration about 20 wt% was diluted with its original solution to 5 wt%, the PSD of nanoceria could be measured indirectly, which accorded well with both that of a suspension prepared directly with near concentration and that from TEM images. Then a method to measure PSD of nanoparticles in concentrated suspension was brought forward.
Electronic and Magnetic Properties of Rare-Earth Atoms Absorbed on Graphene Sheet: A Theoretical Study
Authors: Zhou Qing Xiao , Fu Zhi Bing , Wang Chao Yang , Yang Xi , Yuan Lei , Tang Yong Jian
Published: May 2015

The electronic and magnetic properties of graphene functionalized by 4f-orbital RE-metal atoms (Ce, Nd, Sm and Eu) were investigated by the density functional theory (DFT) calculations. The results of binding energy and geometry parameters showed that the hollow site, the center of a carbon hexagon, was the most stable adsorption structure. Furthermore, the PDOS results suggested that the electronic hybridization between the RE-adatoms and C atoms was mainly contributed by the 5d orbitals, whereas the 4f-orbital of the metal adatoms dominated the net magnetic moments of the systems significantly.
Threshold Model of Micro-Fluidic Inertial Switch Based on Orthogonal Regression Design
Authors: Liu Ting Ting , Su Wei , Wang Chao , Yang Tao
Published: May 2015

The micro-fluidic inertial switch with liquid metal droplet moving under the action of acceleration has overcome the disadvantages of contact bounce, arcing and welding, as are found in the traditional inertial switch. Micro-fluidic inertial switches have no moving parts, a small contact resistance, a long service life and a large current capability. In this paper, we present a micro-fluidic inertial switch that is composed of two-stage micro-valves. This design facilitates tuning of the threshold by adjusting the mercury volume, and so provides better switching performance. Numerical simulation of an orthogonal experiment is used to identify the semi-analytical model of the switch threshold. Results show that the identified model is in accordance with simulation results. Switch prototypes are fabricated by micro-machining techniques including ICP dry etching, sputtering technology and anodic bonding. Centripetal test results show that the switch threshold can be tuned by the careful adjustment of mercury volume.
Study on a Planar Interdigitated MEMS Supercapacitor Using Modeling and Simulation Method
Authors: Dai Ke Ren , Wang Xiao Feng , Lv Wu Shuang , You Zheng
Published: May 2015

In this paper, a modeling and simulation method for planar interdigitated ruthenium oxide MEMS supercapacitor was proposed based on the electrochemical reaction mechanism of supercapacitor. The study simulated the planar interdigitated ruthenium oxide MEMS super capacitor using Comsol software. The highly accurate charge and discharge curves of the super capacitor, electric potential distribution graph and the concentration distribution graph were got through simulation. The effects of two structure-parameters were discussed in the research.
The Influence of Die-Attach Adhesives on the Packaging of MEMS Accelerometer
Authors: Peng Peng , He Xiao Ping , Du Lian Ming , Zhou Wu , Yu Hui Jun , Peng Bei
Published: May 2015

The attachment of the micromechanical silicon die to the substrate is one of the most critical steps in the packaging of highly accurate MEMS (microelectro-mechanical systems) accelerometer. The stress and strains, induced during die-attach process because of TCE (thermal coefficient of expansion) mismatches between different materials, will adversely affect the output characteristics of the accelerometer sensor. In this paper, three different materials: OE138, DG-3S and H70E are selected as the die-attach adhesives of a MEMS comb capacitive accelerometer. The stress and deformation of the silicon die, after the accelerometer model is cured from 80 °C to 20 °C, are evaluated with the aid of finite element analysis (FEA). As the results show, Young’s modulus and the thickness of the adhesives are the most significant factors influencing the stress and deformation of the silicon die. Soft adhesive material (OE138) have better stress absorption, and the stress and deformation of the silicon die decrease with the increasing thickness of the adhesive. Consequently, a soft and thick adhesive is recommended for the die-attach packaging of MEMS accelerometer.
High-Precision Quadrature Signal Generator for Digital Demodulation of MEMS Gyroscope
Authors: Chen Dan Hua , Chen Li , Zhou Hui , Tian Ying
Published: May 2015

A new quadrature signal generator based on Direct Digital Synthesis (DDS) algorithm for digital demodulation of MEMS gyroscope was proposed in this paper. To avoid quantization error, the dual-accumulator with signal-ROM structure was adopted. This signal generator was realized in FPGA chip, which could be quit compact to realize all digital demodulation in one chip. Simulations and tests of the generator were carried out. The test results demonstrate that the signal generator achieves high stability. The standard deviation of the frequency is 0.075Hz and the standard deviation of the amplitude is 0.037mV.
FPGA-Based Test Equipment for System-Level MEMS Switch Series
Authors: Liu Peng , Lou Wen Zhong , Lu Yu Fei , Feng Xin Yu
Published: May 2015

A high-performance, low-cost test equipment system for characterization of MEMS switch is to be proposed in this paper, and the purpose is set to master the fundament of the embedded algorithms of the wafer and system production testing. The team has implemented the real-time analysis for MEMS switch, proving the feasibility of the design, based on the original data collected during the dedicated tests, applying the microsystem hardware designed and assembled by the research team, as well as the embedded software. At the end, the framework of the system platform in the future is described.
Design and Analysis of Capacitive Micromachined Ultrasonic Transducers Based on SU-8
Authors: Li Yu Ping , He Chang De , Zhang Juan Ting , Song Jin Long , Zhang Wen Dong , Xue Chen Yang
Published: May 2015

In this paper, a new capacitive micromachined ultrasonic transducer (CMUT) is designed by using SU-8 material, and the theory of elastic thin plate is used to deduce the relationship between the pressure and capacitance of the structure. Simulation has been done about SU-8 CMUT by finite element method software ANSYS. The deformation of CMUT under acoustic pressure, the relationship between frequency, thickness and sensitivity, as well as the acoustic impedance and reflection coefficient of SU-8 material also have been studied through the simulation. The results turn out that SU-8 has the advantages of big dynamic range, high sensitivity and small acoustic impedance, so it has broad application in the ultrasonic field.
Statistical Analysis and Yield Enhancement of MEMS Devices by Considering Multi-Process Variations
Authors: Gao Li Li , Li Wei Hua , Huang Qing An
Published: May 2015

A methodology is developed statistically to make MEMS devices robust to process variations to improve manufacturability and yield. Two approaches are applied to discuss the effects of multi-process variations. Comparisons have been made between the proposed method and Monte Carlo simulations, which confirm the robustness of the proposed one with performance error less than 4%. Experiments on beams and comb-drive resonator verified the effectiveness of the methodology and it is useful for practical device designs to be more robust to process variations and yield enhancement realization.
A 16 Bits 500 kHz Sigma-Delta DAC for Silicon Micro Gyroscope
Authors: Zhao Ying Kai , Yin Liang , Liu Zhao Tong , Chen Wei Ping , Liu Xiao Wei
Published: May 2015

In this paper, a 16 Bits 500 kHz Sigma-Delta DAC for Silicon Micro Gyroscope is proposedin order to enhance the precision of the digital to analog converter level.The interpolation filterhas achieved 64 times interpolation function,using three cascaded manner, it employs three level cascaded of FIR filterstructure. It achieves a 64 times oversampling feature. The signalbandwidth of the designs interpolation filter is 100 kHz, SNR reach 106dB. Fifth-order single-loop structure CIFB achieve noise shaping modulator function to verify the stability of the system, after the completion of CSD coefficient coding, signal to noise ratio reached 119.7dB, effective bits reached 19.59. The switched capacitor technology actualize analog reconstruction filter module, and using a typically switched capacitor DAC achieved high jump "0, 1" digital signal is converted into an analog signal, the digital-analog conversion achieved.