bluuebunny/crossref_metadata_2025 huggingface dataset:
Research of Street Lighting System Based on Piezoelectric Energy Generator
Authors: Wei Xi Wen , Shi Li Ping , Wei Yan Bo , Huang Jie
Published: April 2014

The paper do some research on the positive piezoelectric effect of piezoelectric ceramic stack. Piezoelectric energy generator is laid on the highway surface, and using the stress which is generated by piezoelectric device to generate electric energy when the vehicle is passing. The generated electric energy is stored in the lithium battery package for street lighting at night after the circuit adjustment. The experimental demonstration and theoretical analysis show that the electric energy generated in piezoelectric stack can be stored in 12V-12Ah lithium battery package within 12h by the circuit of 3F ultracapacitor and LM2575HVT-12V regulator when the output voltage of LM2575HVT-12V is 12V. 12V-12Ah lithium battery package supply energy to the 12V, 12W high power LED lighting for 12h, and meeting the street lighting standards.
Effect of Wrinkled Microstructure on Surface Wettability of Ginkgo Leaves
Authors: Zhao Xiao Li , An Wei Wei , Liu Zhan Shan , Yu Hai Chao
Published: April 2014

In this work, the effect of wrinkled microstructures on surface wettbility of ginkgo leaf was investigated. The upper and lower layers of the ginkgo leaf were comparatively measured by Scanning Electron Microscopy (SEM) for contrast of morphological characters. Measurement results show that the upper epidermis is mainly composed of regularly long-rangle stripes of cellular structures with gently smooth cell wall. On the other hand, the lower one is made up of chaotically isolated cellular structures with wrinkled cell wall. The comparative measurement of contact angle (CA) and roll-off angle in the upper and lower epidermis with deionized water was conducted. Wetting behaviors indicate that the lower has stronger hydrophobicity and weaker adhesion than the upper. Through theoretical analysis, the difference in wettability and adhesion was the result of isolated micro-bumps made by hierarchical wrinkles on the lower epidermis, leading to form solid-air-liquid interface between water and wrinkled surface. This research explains the difference of ginkgo leaf in wettability, and has important reference value in the design and preparation of the surface for the biomimetic materials.
A Transdermal Miniature Syringe Design Based on Port Ontology for Drug Delivery
Authors: Cao Dong Xing , Cao Yi Tong , Li Hui , Wang Xiu Hong , Lei Li Zhu
Published: April 2014

In clinic practice, a strong appeal for painless transdermal injection is pursued, especially for patient drug delivery that cannot be administered orally. A new disposable painless syringe with MEMS technology is presented. The mode of micro needle array and a flexible PDMS container of hemisphere shape are given, and the behavior of the drug liquid flow through the needles is described based on port ontology to model miniature syringe and explains the phenomena of clog formation. The analysis and formulas have theoretically been derived, and the performances and the clog phenomena have been simulated. Therefore, micro needles inserted into the human skin can realize painless injection based on port ontology modeling.
Experiment and Simulation of Hard Cutting System Dynamic Characteristics
Authors: Yue Cai Xu , Yang Yong Heng , Zhong Zhao Nan , Feng Hui Ze
Published: April 2014

Tool wear is an inevitable and continuously aggravated process in precision hard cutting. Interaction between tool wear and dynamic characteristics in cutting system makes machining accuracy and quality of machined surface declining, which effects dynamic characteristics of cutting system significantly. Based on this, cutter dynamic modal parameters of a specific cutting system are measured in this paper. Cutting force and change law of acceleration power spectrum are studied by experiments. Influence mechanism of tool wear on system frequency energy distribution was obtained, and tool wear effects on the system frequency distribution mechanism is obtained. The cutting system dynamic characteristics are quantified by establishing simulation model. Root locus plot of non-uniform load distribution is obtained and the minimum stiffness ratio in the root locus plot is determined. The effect of tool flank wear on cutting system stability in quantitatively stable is researched. Study results provide theoretical basis for selection of stable precision cutting conditions in different tool wear conditions.
Simulation of Nanoimprint Based on PSQ-L Polymer
Authors: Guo Xin , Sun Ming Zhu , Zhao Ming Shan , Zhao Xin
Published: April 2014

A method of simulating nanoimprint process dynamically is proposed and a software program has been made to complete the simulation process automatically. Finite element method (FEM) is used to reveal mechanism of how the liquid flow in the imprint process by every static state. By means of static model iteration,we make a software to simulate the flow process dynamically and it can be used to forecast the result of the nanoimprint. The simulation system is used to predict residual layer thickness in the waveguide fabrication process.
RF Performances of MEMS Suspended Inductor under High Overload Environments
Authors: Lu Chong Ying , Li Jian Hua , Xu Li Xin , Wang Zhi Gang
Published: April 2014

The radio frequency (RF) performances of MEMS suspended spiral inductor under high overload environments are studied. Firstly, a suspended spiral inductor and its MEMS surface micromachining process which is compatible with CMOS process are developed. Then, the mechanical responses and RF performances of the inductor are simulated by ANSYS and HFSS, respectively. The simulation results show that, as the overload increases, the inductance and quality factor decrease significantly when the frequency band is closed to the resonant frequency but have no significant change when the frequency band is much lower than resonant frequency; the resonant frequency of the suspended inductor decreases monotonically with the increase of overload. A modified lumped parameter model is utilized to illustrate the simulation results, which theoretically indicates that the substrate loss is more severe than the ohmic loss as the overload increases.
Experimental Research on WEDM Machining for Metal Components with Micro/Meso-Scale
Authors: Song Man Cang , Du Li Qun , Liu Chong , Liu Jun Shan , Liu Ying
Published: April 2014

In order to meet the machining demand of the metal components with micro/meso-scale, a kind of micro-fabrication method is explored by Wire-cut Electric Discharge Machining (WEDM). To find solutions for the problems of machining, a series of WEDM experiments for the micro/meso-scale structure of a thin nickel plate are carried out based on the analysis of technology regularity of WEDM. Experimental results indicate that the reasonable constraint on the discharge energy is the key to finish the machining of the metal components with micro/meso-scale. The stable machining can be achieved by adjusting discharge parameters to lower levels. The micro/meso-scale machining defects of cantilever distortion and sharp corners bending can be solved by segmented and multiple cutting accordingly. At last, some examples of complex structures machined are shown.
Directly Writing Nanodots on Silicon Surface by Combined-Dynamic Dip-Pen Nanolithography
Authors: Yang Li Jun , Cui Jian Lei , Wang Yang , Guo Shou Wu , Xie Hui , Sun Li Ning
Published: April 2014

Dip-pen nanolithography (DPN), based on atomic force microscope (AFM) system, is an effective method for nanoscale science and engineering, and the potential applications of DPN will be shown in the field of nanomechanics, nanomaterials, nanobiotechnology, nanomedicine. And the novel combined-dynamic mode DPN (CDDPN), rather than mostly used contact mode DPN or tapping mode DPN, becomes the important tool for the fabrication of nanodots with the direct-writing method of depositing the ink onto the hard silicon surface at the predetermined position, which is presented in the corresponding experiments. In addition, the size of nanodots gradually decreases in the diameter with the increase of the number of nanodots in the case of AFM tip dipping in ink once. However, the size in height does not monotonically reduce as the reduction of the ink, which is affected by the interaction among the relative humidity, AFM tip, substrate material, surface roughness, etc. For the better nanolithography quality of the nanodot, the nanolithography process, under the optimized process parameters, is accomplished once without the intermediate scan imaging process as much as possible.
Design and Fabrication of BaTiO3 Crystal Thin-Film Waveguides
Authors: Zhang Jing , Fu Xiu Hua , Guo Li Jun , Zhou Jian Hong , Liu Dong Mei , Sun Deg Gui
Published: April 2014

BaTiO3 crystal film has the very high electro-optic effect, so it has important research value for thin film waveguide electro-optic modulators. In this work, BPM software is used to simulate the single-mode condition of ridge waveguide at first, then BaTiO3 film waveguide structure is designed with suitable film thickness.BaTiO3 waveguide thin films are grown by pulsed laser deposition on single crystal MgO substrate. The BaTiO3 thin-film crystalline structures grown at different temperature sand different laser powers were analyzed by using X ray diffraction , which showed the BaTiO3 films have a priority crystallization direction and good crystallization quality at 750°C grown temperature. For the optimally-designed waveguide structures, the PECVD technique and ICP plasma etching method are employed to coat and etch Si3N4 films, respectively. Through the optimization of main process parameters, 60 sccm reaction gas flow and 150 nm/min etching speed are finally selected to create the ridge waveguides, and consequently, the surface roughness of Si3N4 film waveguide reaches 2.3 nm.
Effects of Electrolyte Composition on the Properties of Micro-Arc Oxidation Coatings Formed on 6063 Alloy
Authors: Wu Xin , Liu Qing Min , Li Hong Xia
Published: April 2014

Micro-arc oxidation (MAO) coating was prepared in different electrolyte compositions on 6063 alloy and its characterizations were detected by X-ray diffractometer (XRD), scanning electric microscope (SEM), energy dispersive X-ray spectrometer (EDX) and Vickers hardness tester. Friction and wear behaviors of the coatings were tested without lubrication and the abrasion loss was measured after the friction test. The results showed that the MAO coatings, presenting rough and porous surface and high hardness, mainly consisted of α-Al2O3 and γ-Al2O3 phases. The composition of electrolytic solution had great influence on the coating morphology and its mechanical performance. Compared with the coating prepared in silicate and borate solutions, the coating prepared in aluminate solution had not only denser and smoother surface but also higher micro-hardness value and better abrasion resistance.
Fabrication of Bi2Te3 Nanowires Applied in Thermoelectric Generators
Authors: Ren Da Hai , Yang Zhen Heng , Chang Yi Na , Dai Zhen Yu , You Zheng
Published: April 2014

Compared with block and quantum well thin-film materials, nanowire materials can have better thermoelectric properties and higher merit of ZT values. Electro-chemistry method was used to deposit nanowires in the highly ordered holes of AAO (Anodic Aluminum Oxide). Several conditions were discussed and experimented to determine an appropriate condition for the co-deposition of Bi and Te. Some optimization measures are proposed to obtain more stable fabrication results. Analysis demonstrates that the nanowire grew along the pores from the bottom to the top.
Study on the Photocatalytic Degradation of Diesel Pollutants in Seawater by a Prepared Nano Ag-Droped Zinc Oxide
Authors: Yu Xiao Cai , Hu Dong Dong , Chen Jin Fang , Jin Xiao Jie , Zheng Xu
Published: April 2014

ZnO and Ag-droped ZnO photocatalysts with different Ag loadings (0.5, 1.0, 1.5, 2.0at%) and different calcination temperature (300, 400, 500, 600, 700°C) were synthesized by a sonochemical method. The morphology and crystal pattern of some prepared catalysts were characterized by XRD and SEM techniques which demonstrated that the prepared catalysts were of hexagonal wurtzite structure. Ag loadings, calcination temperature and other factors, dosage of photocatalyst, reaction time and pH value of seawater, were also taken into consideration in the procedure of photocatalytic degradation reaction under UV light. An orthogonal experiment was carried out to investigate the best combination of factors which can reach the best diesel pollution removal rate and the influence order of factors. Reaction time and dosage of catalyst were the most influential factors in this experiment, and the factor of calcination temperature was the weakest influential factor. The removal rate of diesel can up to 78% when the experiment was undertaken under the very conditions: the dosage of catalyst 2.0g/L, reaction time 2.0h, Ag loading of catalyst 1.0 at%, calcinations temperature 400°C and pH value 8.5.
Comparable Studies on Photocatalytic Activities of Ag3PO4 Microspheres and Polyhedrons
Authors: Wang Bo , Gu Xiu Quan
Published: April 2014

In this study, spherical and cubic Ag3PO4 microcrystals were prepared by a facile liquid chemical method and characterized by the XRD, SEM and UV-visible spectrometry. It was found that the as-prepared Ag3PO4 cubes showed the higher photocatalytic activity and stability than the sphere under visible-light irradiation in degrading Rhodamine B (RhB). The enhanced photocatalytic activity of the Ag3PO4 polyhedron might be attributed to a higher active surface energy of the former one.
Synthesis and Luminescent Properties of Eu3+ Doped Lu2O3 Powders Using Micro-Emulsion
Authors: Zhong Yu Rong , Zhao Man , Xu Bao Long
Published: April 2014

Europium-doped lutetium (Lu2O3:Eu3+ ) powders were prepared by micro-emulsion method. A small amount of an aqueous solution of Lu(NO3)3, Eu(NO3)3 and aqueous ammonia was slowly dropped into the water-in-oil micro-emulsion system (water / cetyl trimethyl ammonium bromide (CTAB) / n-butyl alcohol and cyclohexane) under vigorous stirring at 80 °C. The precipitates were obtained by Ostwald’s ripening at 250 °C for 6 h, which were then heated at 400 °C, 600 °C and 800 °C. The SEM morphology showed that the powders were rods of about few hundred nanometers in length and 40 nm in diameter. The spectrograms of X-ray diffraction (XRD) demonstrated that the Lu2O3:Eu3+ crystallinity was enhanced with the increasing of temperature. The photoluminescence results revealed that the intense emission bands centered at 612 nm. This method provides a new way to obtain different morphology and luminescent properties of Lu2O3:Eu3+ powder.
Equivalent Mechanical Properties of Graphene Predicted by an Improved Molecular Structural Mechanics Model
Authors: Cheng Yuan Zheng , Shi Guang Yu
Published: April 2014

Based on molecular mechanics and the stick-spiral model, this paper first presents the analytical analysis of the effective in-plane mechanical properties of both zigzag and armchair monolayer graphene sheets. We find that the equivalent in-plane elastic constants of monolayer graphene sheets are the same in the two principal directions of graphene. The effective in-plane mechanical properties of graphene are then evaluated numerically using an improved molecular structural mechanics (MSM) model, in which the flexible connections are used to characterize the bond angle variations of graphene. Furthermore, the effective bending rigidity of the beam representing a C-C bond in this improved MSM model is determined from the energy equivalence over the basic cell of graphene and the force constants given by molecular mechanics. A rigidly connected frame model with the bending stiffness of the equivalent beams for C-C bonds different from the existing structural mechanics model is also used to evaluate the mechanical properties of graphene. The flexibly connected frame model gives very good results of Youngs modulus and Poisson ratio of monolayer graphene sheet. The new rigidly connected frame model presented here also gives improved results than the existing rigidly connected frame model of graphene.
A Study of Abrasive Rotating Velocity Effect on Monocrystalline Silicon in Ultra-Precision Mechanical Polishing via Molecular Dynamic Simulation
Authors: Yang Yi Han , Zhao Hong Wei , Liu Hong Da , Zhang Lin
Published: April 2014

A three-dimensional molecular dynamics (MD) simulation is conducted to investigate the effect of the abrasive rotating velocity on monocrystalline silicon specimen by mechanical polishing at atomistic scale. By monitoring relative positions of atoms in the monocrystalline silicon specimen, the microstructure of monocrystalline silicon is clearly identified and analyzed. The simulation results show that better machined surface quality is obtained and more phase transformation atoms occur with small abrasive rotating velocity. When the abrasive rotating is high, the surface quality deteriorates and amorphous layer thickens.These results provide us an effective approach to analyze the mechanism of material deformation and the formation of the machined surface after ultra-precision polishing.
Research on Multi-Walled Carbon Nanotubes by Fiber Laser Irradiation
Authors: Su Quan Shuang , Chen Ji Min , Liu Fu Rong
Published: April 2014

In this paper we report Multi-walled carbon nanotubes (MWCNTs) have been joined together by continuous wave fiber laser operating at 1064 nm. The SEM image clearly shows that there are obvious melting - solidified phenomenon between the jointed Multi-walled carbon nanotubes. MWCNTs wall was complete and smooth without destruction phenomenon. The new graphite layers were found in the connection with transmission electron microscopy (TEM). Besides, we observed that the present multi-walled carbon nanotubes showed the trend of melting connecting to destruction as the laser irradiation time increased in the case of a certain power density. In the end, there were recrystallization phenomena during MWCNTs joining with the Raman spectra. The crystallinity and length to diameter ratio decreased following the increasing irradiation time.
Change the Magnetic Properties of Electroplated Core Films to Improve Micro-Fluxgate Performance
Authors: Guo Bo , Liu Shi Bin , Yang Shang Lin , Feng Wen Guang , Li Ju Ping
Published: April 2014

It is very important for micro-fluxgate to reduce its power consumption because higher power consumption causing serious cooling problem which will lead series of questions. In this paper the influence of core film magnetic properties (coercive force Hc and saturation field Hs) on optimum excitation current (OEC) and sensitivity are investigated theoretically. The expressions of optimum excitation magnetic and maximum sensitivity were given. In the field of magnetic material, lower Hc means better soft magnetic properties, but when analyze the effect of Hs and Hc on the OEC and corresponded sensitivity we find that low Hs and high Hc bring low OEC and high sensitivity. Applied magnetic fields at different angles during electroplating and annealing are introduced to improve magnetic properties of electroplated core films. In subsequent experiment we test the OEC, sensitivity, linear range and magnetic noise of fluxgate utilize these core films. Plating with θ=0° (θ is the angle between applied magnetic field and long edge of the core) samples obtain lowest OEC and highest sensitivity, plating with θ=90° and annealed samples obtain large linear range, annealed samples obtain lowest magnetic noise.
Study on Preparation of Chitosan Microspheres Loaded with Levofloxacin
Authors: Guan Jing , Cheng Peng , Huang Shu Jie , Li Zhi Hong , Zhang Xi Zheng , Wu Ji Min , Guo Yong , Li Rui Xin
Published: April 2014

Chitosan (CS) microspheres loaded with levofloxacin (LOF) were prepared by emulsion crosslinking technique and the experimental parameters were optimized by orthogonal tests. The influences of various factors on the combination properties of chitosan microspheres were discussed. The optimal preparation condition was 98000 chitosan molecular weight, 30mg/ml chitosan concentration, 5:1 volume ratio of oil to water, 1:1 molar ratio of amino group of chitosan to aldehyde group of glutaraldehyde (GA), 1500 rpm stirring rate, 2:1 mass ratio of chitosan to levofloxacin and 1 h crosslinking time. The CS microspheres prepared under optimal parameters had spherical morphology with 1.59 μm of average geometric diameter and 0.99 of span, its loading capacity (LC) and association efficiency (AE) values were 21.71% and 80.49% respectively. In vitro release profile showed the levofloxacin released fast initially, and then slowly from the microspheres with T90 occurring at 188.5h and its delivery behavior conformed to First-Order release kinetics model.
Investigation on Dissolving Process of Secondary Phases and Austenitic Grain Growth in a Microalloyed Steel
Authors: Hao Bin , Zhang Xiao Juan , Yuan Shao Qiang , Liang Guo Li
Published: April 2014

The secondary phases such as carbonitrides in the microalloyed steel play very important roles in retarding the austenitic grains growth during reheating. The dissolving process of carbonitrides containing Nb, Ti, Mo will affect the austenitic grain sizes directly. In the present work, the dissolving behaviors of secondary phases in low carbon microalloyed steel during isothermal holding at different temperatures were investigated by electrolytic experiment, carbon extraction replicas, TEM and EDX analysis. Meanwhile, the austenitic grain sizes were measured corresponding to the temperatures. The experimental results indicate that there are two types of carbonitrides in as-forged steel. One is the coarsened Ti-rich precipitates originated from solidification, and the other is the finer Nb-rich particles attributed to strain-induced process. The strain-induced precipitates disappear after being held for 1 h at 1000°C. At 1000~1220 °C, the austenitic grains grow obviously due to rapid dissolving of the carbonitrides containing Nb and Mo. However, some undissolved Nb, Ti carbidenitrides still hinder the grain boundary migration. When the reheating temperature rises to 1270°C, the grain size grows abnormally after being held for 2h. At the holding temperature, few Nb-bearing TiN precipitates can be stable while the pinning effect weakens markedly.
Smoothness Control of Wet Etched Si{100} Surfaces in TMAH+Triton
Authors: Tang Bin , Yao Ming Qiu , Tan Gang , Pal Prem , Sato Kazuo , Su Wei
Published: April 2014

The effect of galvanic interaction between the evolving facets of the etch front on the Si {100} surface smoothness during wet anisotropic etching in surfactant-added tetramethylammonium hydroxide (TMAH) is studied by etching different mask patterns. Triton X-100, with formula C14H22O(C2H4O)n, where n=9-10, is used as the surfactant. The different smoothness of wet etched Si {100} surfaces, evaluated by atomic force microscope (AFM) and optical microscope, indicates that the wet etched Si {100} surfaces could become extremely smooth after the onset of the electrochemical etching contribution. A model to account for the galvanic interaction between the evolving facets is proposed, demonstrating that the chemical etching can be significantly surpassed by the electrochemical etching when the relative area of the exposed {100} surfaces are relatively small in comparison to that of the developed {111} sidewalls. Additionally, silicon beams with smooth surfaces are presented in the fabrication of a sandwich micro accelerometer to avoid the risk of device invalidation. This study is useful for engineering applications where the fabrication of microstructures for high quality devices should contain smooth surfaces.
The Fabrication of High Resistance-Temperature-Coefficient Vanadium Oxide Film by Magnetron Sputtering Method
Authors: Qiao Ya , Ling Yong Shun , Lu Yuan , Yang Hua
Published: April 2014

Direct current (DC) magnetron sputtering method was used to deposit vanadium oxide thin films on ordinary glass substrates from a vanadium metal target and a five factors four levels orthogonal experimental method was used to find the best combination of sputtering pressure, sputtering power, oxygen/argon flow ratio, substrate temperature and deposition time for fabricating high temperature coefficient of resistance (TCR) vanadium oxide film. The results indicate that a good combination of these parameters should be 1Pa, 160W, 1.5/25, 280°C and 60 minutes. And the film fabricated using this parameters combination is mainly composed of V2O5and has a resistance range of 80.3kΩ to 40kΩ while its temperature changed from 20°C to 80°C.
The Research of Gypsum Investment Mould Used as Forming Micro-Castings
Authors: Wang Guo Tian , Ren Ming Xing , Li Bang Sheng , Fu Heng Zhi
Published: April 2014

By applying ultrasonic solidification, gypsum based micro casting mold with different chemical compositions were sintered at different temperatures. The influence of processing parameters and sintering temperature on the microstructure and surface roughness were investigated. Meanwhile, the effect of sintering temperature on the bending strength was studied. The result showed that the nucleation rate of gypsum can be significantly improved under high temperature and pressure, which was caused by the effect of ultrasonic cavitation. Under the frequency of 100 KHz and the power of 200 W, 20 min, the morphology of gypsum transfers from flake and needle into near spherical after 20 min, and the grain size can be refined to around 500 nm. The value node of surface roughness occurs at the sintering temperature of 600 °C. The surface roughness is the lowest when the gypsum content is 60% and under the sintering temperature of 600 °C, which can reach Ra ~ 0.22 um. The bending strength of mold roughly increased with the increase of content of gypsum. There is no obvious rule for the mold strength with the change of sintering temperature. The mold strength reaches the highest value when the sintering temperature is 600°C.
Size Distributions of Mesophase Microbeads Obtained from Heterogeneous and Homogeneous Systems
Authors: Zhang Wen Wen , Liu Xiu Jun , Li Tong Qi , Fan Zhen
Published: April 2014

Mesophase microbeads were prepared by thermal condensation in the presence of heterogeneous and homogeneous systems. Morphologies and sizes of mesophase microbeads are characterized by scanning electronic microcopy (SEM), polarized light optical microphotography (PLOM) and laser particle size analyzer. SEM and PLOM results exhibit that mesophase microbeads have a narrow size distribution and many large particle in heterogeneous system. In homogeneous system, there are a great deal of smaller mesophase microbeads and a very little of larger mesophase microbeads. The laser particle size analysis results show that size distribution of mesophase microbeads in heterogeneous system is quite different from that in homogeneous system. There are multi-peaks on volume distribution curve in heterogeneous system. Larger mesophase microbeads are mainly in tens micron peak of size distribution curve. In homogeneous system, particle size of mesophase microbeads has a wide distribution and only single peak on size distribution curve. Moreover, sulfur concentration in reaction system makes the size of mesophase microbeads increase and the size distribution curve move to larger particle diameter. But sulfur concentration can not affect the curve pattern of size distribution.
Effect of Joule Heat on Hydrophily of Microchannel
Authors: Han Xiao Wei , Liu Xiao Wei , Tian Li , Zhang He , Liu Yao , Mao Zhi Gang
Published: April 2014

We discuss the effect of joule heat which comes from eletroosmosis flow on the microfluidic chip. Our microfluidic chips are fabricated from polymethyl methacrylate (PMMA). As everyone knows, PMMA is a poor conductor of heat, and its transfer coefficient is only 0.19W/m·K in room temperature. So, the heat is generated by eletroosmosis canʼt conduct outside the microchannels of microfluidic chip easily. We research the effect joule heat on walls of microchannels which are made of PMMA. During our study, interior surface of microchannelsʼ hydrophobicity is changed by effect of joule heat.
Effects of Wall Slip on Filling Flow for Polymer Melt in Micro Injection Molding
Authors: Zhuang Jian , Zhang Ya Jun , Wu Da Ming , Liu Li Zhu , Sun Cheng Jun , Wang Wei , Liu Shui Xing
Published: April 2014

Effect of wall slip on melt filling flow behaviors in micro injection molding are investigated based on analysis of wall slip mechanism for polymer melt flowing at filling stage. By means of comparisons, slip coefficients in different microchannels are confirmed. With finite element method, the relationship between slip velocity and inlet flow rate or length-diameter ratio is analyzed. The results indicate that the wall slip happen for polymeric melt in microchannels, and slip coefficients are related with the size characteristics of microchannels. Moreover, wall slip velocity has the size effect and increase with the decrease of the section size of microchannels, which cause melt velocity distribution to smooth. At the same time, slip velocity is proportional to length-diameter ratio of microchannel, namely when wall shear stress is uniform, the slip velocity rises with increasing length-diameter ratio of microchannel.
Effect of Electrolytic Temperature on Nano-Hydroapatite Deposition on ASD Bioceramic Films
Authors: Ma Xiao Ni , Zhang Li Hua , Zheng Li Xue , Yang Zhan Hua , Gao Qing , Li Ying , Liu Xiao Hua , Li Feng , Han Ji Qin , Xu Xin
Published: April 2014

Anodic spark deposition (ASD) is a novel technique to deposit bioceramic films on the surface of titanium (Ti) and its alloys, and the films prepared with nano/micro scale pores are characterized by high-quality performance for dental implant. Among the process parameters, electrolyte provides a leading role owing to its vital influence not only on the films chemistry but also on the electrical conductivity of the circuit, which affects the film properties. In this study, titania porous films were synthesized by ASD and the effect of electrolytic temperature on microstructure and chemical composition of the films was studied. The results show that the electrolytic temperature could significantly influence the surface topography, thickness and chemical composition of the oxidation films produced by ASD and, therefore, determined the layered hydroapatite (HA) deposition as the other process parameters were fixed.
A Test Droplets Dispensing Solution for Digital Microfluidic Biochip Parallel Testing
Authors: Zhang Ling , Mei Jun Jin , Yan Bo Wu , Gao Qin
Published: April 2014

Digital microfluidic Biochips are widely used on safety-critical biomedical applications, and dependability is an essential attribute for them. To reduce dispensing time, a new test droplets dispensing solution for digital microfluidic biochip parallel testing is proposed in the paper, where multiple test droplets are allotted to the limited test dispensing sources to transmit them to the corresponding test target. The goal is minimizing the dispensing time, and then reduces the system testing time. Even thought the problem is shown to be NP-complete, it can be solved exactly for practical instances using integer linear programming (ILP). The experimental results demonstrate that optimal solutions to the test droplets dispensing problem in microfluidic biochip parallel testing are indeed feasible.
Numerical Simulation of the LCP Hele-Shaw Flow Based on the Injection Molding Process
Authors: Liu Chun Bo , Sun Jian Ye
Published: April 2014

In order to broaden the application range of LCP, the simulation of the LCP Hele-Shaw flow in the square cavity was conducted. The temperature of the cavity was constant 300°C. In the simulation the Leslie-Ericksen and TIF theories were used. With this simulation results, we can predict the position of the flow front at any time during the whole injection process and grasp the change of the pressure field and the velocity field. The change of the pressure and the velocity fields were very slow, there was no distortion point in the whole flow field. In the layer near the wall, the directors arranged evenly according to the direction of the flow and in the center layer it was decided by the shear rate in the X-Y plane.
Noncircular Tool Fabrication by WEDG Using Electrode Jump Motion and Noncircular Array Holes Drilling
Authors: Wang Yan Qing , Bai Ji Cheng , Zhu Guo Zheng
Published: April 2014

Electrode jump motion strategy was adopted to fabricate noncircular tool using wire electrical discharge grinding (WEDG). The machining procedure and electrode jump motion strategy for noncircular tool fabrication were determined through experiments. This approach has been verified by successfully machining of rectangular electrode (38μm×38μm, 700μm length) and D-shaped electrode (diameter 45μm, height 42μm, 500μm length). D-shaped array holes of 6×6 matrix were drilled using corresponding single noncircular tool which was manufactured by the adopted machining approach. The array holes have tight diameter tolerance and height tolerance which are both less than 2μm, and positioning errors are both less than 1μm in the direction of the X, Y-axes.
Research on Fabrication and Electronic Characteristics of Dual-Extended Nano Structure Memristor
Authors: Bai Xiao Hui , Wen Dian Zhong , Con Celal , Jian Zhang , Yavuz Mustafa , Bo Cui
Published: April 2014

This paper proposes a novel dual-extended nanostructure memristor model compared to HP memristor can be called Single-extended memristor. Oxygen ions and oxygen vacancies all are effective carriers in this memristor as the structure are made of TiO2-x/TiO2/TiO2+xthree nanolayers between Pt electrodes.The sample of dual-extended memristors arrays were fabricated by ways which these cost-effective methods can be exploited to produce memristors with nanoscale electrode width. Dual-extended nanostructure memristor model will be represented and the mechanism will be discussed. Fabrication methods of the memristor device are introduced and the electronic characteristics are measured and plotted. The results are discussed will experimentally demonstrated that higher switching speed and lower power will be gained by using dual-extended memristors to design IC.
Fabrication of the Silicon-Based Three-Dimension Neural Probe Arrays
Authors: Zhuang Yi Wei , Cheng Zheng Xi , Zhang Xue Min , Yuan Hong Hui
Published: April 2014

The neural probe array is an important tool for getting the neural signals. Giving consideration to the biological compatibility and the demand of integrating in circuit, new fabrication process of a silicon-based three-dimension neural probe array was reported. The idea about milling in mechanical process and the method of structure for transfer were introduced in the fabrication. The 10*10 scale silicon-based three-dimension probe arrays integrated in the readout circuit directly were fabricated by means of flip chip and multi-blade mixing dicing techniques. In the entire fabrication process, no any high-temperature process and silicon wet etching process, which would damage the circuit, were included. Using the fabrication process above, the 10*10 scale silicon-based probe arrays with centre-to-centre separation of 400 μm were achieved. In the probe arrays, whose good rate was more than 95%, the width of a single probe was 100 μm, the tip angle was 25o, and the height was more than 1.4 mm. Through the fabrication process, it was not only reducing the pin count greatly, but also simplifying the interface effectively. By the in vivo experiment of the Sprague Dawley rat, the corresponding nerve signal was obtained.
Design of Intelligent Meteorological System Based on MEMS
Authors: Wang Hao , Nie Meng , Huang Qing An
Published: April 2014

Intelligent weather station system based on MEMS sensors is designed. The automatic meteorological system includes a MEMS temperature sensor, MEMS humidity sensor, MEMS pressure sensor, MEMS wind speed sensor and the sensor intelligent control system, etc. The intelligent control system has functions such as precise timing, multiple sensor data automatic acquisition, storage and uploading, which realizes the intelligent control of this weather station system.
Study on Shock Resistance of MEMS Devices with Different Stoppers
Authors: Jiang Tao , Wei Yun , Yao Sai , Zhou Jian
Published: April 2014

The shock resistance of the MEMS device can be improved by simplifying its structure, but it will reduce accuracy. A commonly implemented solution that strengthens the shock resistance is the use of stopper. However, the collision between MEMS structure and stopper in shock environment may lead to the failure of the device. Hence, stopper should have a fine protection performance. In this study, the design method and principle of the MEMS device in the shock environment were analyzed. It was pointed out that the reliability design methodology of the MEMS device based on statics theory was insufficient. Next, the response of MEMS device to shock was studied and the shock dynamics model was established. Based on the model, the shock response of the traditional design and designs with different stoppers were analyzed. At last, experiments were carried out and the protection performance of different stoppers was evaluated. Results show that the use of stopper can obviously improve the shock resistance of the device. Elastic stopper can strengthen the shock resistance of the device greatly because of the excellent protection ability, while hard stopper may cause the emergence of the sharp stress wave.
Corner Effect of Micro-Comb Capacitive Structure
Authors: Liu Hai Peng , Gao Shi Qiao , Jin Lei , He Yun Li
Published: April 2014

The comb-shaped capacitive micro-machined gyroscope employing an electrostatic comb drive and capacitive sensing structure is a typical type of MEMS sensor. Because of design and processing limitation and other factors, there are problems related to parallelism, dimensional accuracy and shape accuracy of the fabricated comb capacitor. These problems induce error into the calculation of the capacitance of the comb capacitor. The capacitance of the comb capacitor can be better calculated by the modeling the corner effect with various equipotential lines.
Study on MEMS Capacitive Differential Pressure Sensor
Authors: Hou Zhi Hao , Huang Zhen , Jia Shi Xing
Published: April 2014

The design and fabrication of MEMS capacitive differential pressure sensor is reported. Silicon membrane is used as movable electrode. Gold metal film on glass is used as fixed electrode. Anodic bonding is used to bond together the silicon and glass to form the capacitive pressure sensor. The measurement capacitance of the sensors is 5.37 pF at an applied pressure of 0 kPa and 7.26 pF and the full operating range of 40 kPa.The ratio of changed to initial capacitance was 0.35. The error of the MEMS capacitive pressure sensor is less than 4‰ full-scale(FS) by using quadratic curve fitting which can meet most application requirements.
A Wireless Power-Free Pressure Sensor for Real-Time In Vivo Gastrointestinal Pressure Monitoring
Authors: Shi Qiang , Chen De Yong , Wang Jun Bo , Bao Kai Kai , Liu Li Juan
Published: April 2014

A wireless and power-free pressure sensor system capable of real time in vivo gastrointestinal pressure monitoring has been developed. This system contains a sensor unit and a detection unit. Based on mutual inductance detection mechanism, the sensor is featured with simple device structure and therefore low cost. The packaged sensor unit was tested. Results obtained from experiment demonstrated that this sensor has a sensitivity of 0.2115 kHz / kPa within a pressure range-10~30 kPa. The in vivo testing result not only indicates a period of 2 contractions per minute peristalsis of rabbit stomach but also validates the feasibility of this real time wireless gastrointestinal pressure monitoring system.
Case Studies of Steel and their Welded Joint Failures Caused by LME
Authors: Bernasovský Peter
Published: April 2014

Liquid metal embrittlement ( LME ) is a phenomenon , where liquid (molten ) metal is mostly intergranulary (but not only ) penetrated into solid metal and causes its brittle fracture. The LME is usually related to low melting metals (zink, tin , cadmium ...) ,which are in the contact with higher molten ones ( steels, Ni alloys...). Cases of LME as a Cu penetration into pipeline welded joint of 15G2S steel ,a hot temperature corrosion in the cement works shell plate made of AISI 310 stainless steel attacted by Ni3S2 (Ts= 644°C) and a vanadium corrosion in the boiler vessel (10CrMo9-10 steel) due to V2O5 + Na2SO4 eutecticum (~600°C ) are concerned.
Metallography of CB2 Steel Used for Cast Turbine Components
Authors: Kasl Josef , Jandová Dagmar
Published: April 2014

Steel CB2 developed in frame of the COST actions belongs to the most promising steel for production of cast turbine components working at ultra-supercritical steam conditions. VZÚ Plzeň has participated on assessment of original trial melt CB2 as well as on testing of samples coming from one of pilot valves produced of steel CB2 in full scale. Recently VZÚ Plzeň has cooperated with Doosan Škoda Power in development of weld processes of advanced power energy steels including steel CB2. This contribution deals with a comparison of properties of the steel CB2 produced by four various steelmakers from point of view of their microstructure in relation with their mechanical and creep resistant properties. Evaluation is focused on chemical heterogeneity, porosity, content of non-metallic inclusions, in particular on an occurrence of coarse NB, microstructure and substructure using methods of light and electron microscopy.
Microstructural Investigations on Vespa Scooter Gear Parts over a Production Period of 50 Years
Authors: Meyer Michael , Strobl Susanne , Haubner Roland
Published: April 2014

Vespa scooters have been produced since the end of the 50th, and mechanical parts are produced in license and several reproductions are available. Service centres should know the material properties of the various spare parts for repairing gears. 6 cogwheels and 7 changing gear crosses from various productions were selected (VBA - end of 50th, GL150 - 1961, PE - end of 70th, PX200E - 1998, LML 125 - 2008, MEC-EUR - 2010). The analytical investigations showed that 16NiCr4 steel was used mainly for the cogwheels and 18NiCrMo14-6 steel for the changing gear crosses. The samples show negligible differences for elemental composition, impurities and defect distribution. Depending on the various parts the carbon and the hardness gradients from the surface to the core are different. The hardened steel samples showed typical martensitic-bainitic microstructures.
The material properties of the different gear parts were compared to find optimal solutions for servicing Vespa gears.
Magnetic and Martensitic Transformations in Ni46Mn41.5-xFexSn12.5 Melt Spun Ribbons
Authors: Maziarz Wojciech , Czaja Paweł , Dutkiewicz Jan , Wróblewski Rafał , Leonowicz Marcin
Published: April 2014

Four alloys with nominal compositions Ni46Mn41.5-xFexSn12.5 (x=0, 2, 4, 6 at.%) were cast in an induction vacuum furnace and homogenized. Then they were melted in quartz tubes and ejected onto a rotating copper wheel to produce ribbons. The X-Ray phase analyses of as melt spun ribbons have shown that in both, the ternary as well as in the quaternary alloys a single phase of the Heusler L21 type ordered structure was found. The characteristic temperatures of magnetic (TC) and martensitic (Ms) transformations were determined by a vibrating sample magnetometer (VSM). Both the Ms and TC increase with the increase of Fe content in all alloys, which is in accordance with the theory of valence electron concentration (e/a) influence on Ms. The phase structures, chemical compositions, grains sizes and type of microsegregation were characterized by transmission electron microscope (TEM). The equi-axed grains of size from 0.95 to 1.7 μm were observed in all ribbons. The grains posses the L21 structure at room temperature, however in the alloys with higher Fe content the different type of martensite was observed at the grain boundaries of L21 phase. Appearance of this martensite was explained in relation to microsegregation of particular elements during melt spinning process and simultaneous change in the e/a ratio.
Star Cracks in Continuously Cast Deep-Drawing Tin Steel Slab
Authors: Duška Jaroslav , Grimplini Gabriel , Molnár Marek , Hrabčáková Lucia , Drotár Atila
Published: April 2014

The final quality of flat products is directly related to surface and internal quality of continuously cast slabs. This aspect is very important especially in case of IF and deep-drawing tin grades, in which even the smallest defects can cause problem in the final processing of the material, especially during forming by stamping, when the material fails. This work is devoted to the analysis of the surface defect of star crack type. The presence of defect was visually detected after scarfing process during removal of surface layer on the small radius side of the slab. This type of defect occurs particularly in cases, when steel is contaminated by copper in the process of continuous slab casting. In view of the copper melting point (1083°C) and the surface temperature of the cast slab shell at the mold exit (about 1200°C) in the process of steel cooling at continuous casting, Cu penetrates along the boundaries of primary austenitic grain, or separate particles are precipitated at the grain boundaries. Initial cracks are formed in the area of primary cooling in the mold. Thermal and mechanical stresses acting in the surface area of slab shell when the slab passes thorough the rollers of secondary cooling cause gradual expansion of crack defects along boundaries of grains contaminated by copper.
Surface Defect on Hot Rolled Steel Sheet with Cu Content
Authors: Hrabčáková Lucia , Duška Jaroslav , Mašlejová Alica
Published: April 2014

Structural steel grades S235JRCCu+N and S355JRCCu+N with 0.25 – 0.35% copper content are intended for products with increased corrosion resistance. They are used for railcar and container bodies. The low copper alloying strongly increases the material life-time in the conditions of atmospheric corrosion. Sheets with fine sharp needle-type bodies on both sheet surfaces were delivered for the analysis. As per the customer information, they were present on almost whole length of on cast strips. Considering the steel copper content, it was assumed that the improper steel alloying was the reason of imperfection. Chemical composition results didn’t confirm this expectation. Metallographic analysis should determine the imperfection origin and decide if copper presence was the primary factor of it. The analyses using SEM coupled with EDS analyzer have shown that the sliver-type defects, few millimeters long bands of ductile iron oxides, were present in very small material depth of about 50 – 150 μm in the analyzed material The bands were formed in more layers parallel to the sheet surface; their thickness was similar to the thickness of surface scales. Oxidic material under the sliver had the same micro-morphology and chemical composition like the scales on the sheet surface. Very fine globular copper particles were randomly and very sporadically present in the layer of ductile oxides in slivers and also in surface scale. Besides this, the material in defect area was chemically homogeneous and no particles were found in the layer boundaries. Copper particles were not detected in the steel basic material; the copper was dissolved in the matrix. The nature of imperfection was typical for V-shaped slivers, caused by overheating sheet surface in reheat furnace. After revising technical conditions of reheat furnace operation, this imperfection type was suppressed.