塑料电泳芯片微结构模压的试验研究

塑料电泳芯片具有绝缘性、透光性好,材料价格便宜,成型容易,批量生产成本低等优点,是一种新型微型分析装置。研究塑料电泳芯片微通道模压的工艺过程和工艺参数,通过试验建立微通道尺寸与模板微凸起尺寸和模压工艺参数的关系,在此基础上提出了一种新的模压工艺,对于完善塑料电泳芯片结构设计和制作的基本理论和基本技术均有较大意义。

微孔模压小炭块的开发与应用

根据高炉炉底炉缸的破损机理,选用优质电煅烧无烟煤为主要原料,煤沥青或沥青和酚醛树脂为粘结剂,并加入特殊添加剂,采用高压模压成型、高温烧成、精磨加工工艺生产的微孔模压小炭块具有优良的理化性能。中小型高炉使用微孔模压小炭块,有望解决炉底炉缸大炭块“环状断裂”和“蒜头状”异常侵蚀问题,可使高炉一代寿命达到10～15年。

薄板微成形工艺的研究现状及发展趋势

薄板微成形是一种比较重要的制造板料的方法,它在实际中的应用非常广泛,可以形成结构不同和角度不同的各种复杂的零件。现在薄板的微成形在集成电路行业和和电行业的应用特别多,塑料成形有关的领域正在大力支持研究薄板的微成形技术。在薄板微成形方面,主要进行薄板的微拉深、微冲裁和微弯曲等。本文结合前人研究,对薄板微成形工艺的研究现状及发展趋势问题进行探析。

微孔模压小炭块的开发应用

根据高炉炉底炉缸的破损机理，我们选用优质电煅烧无烟煤为主要原料，煤沥青或改性沥青为粘结剂，加入特殊添加剂，采用高压模压成型，高温烧成。精磨加工工艺而生产的微孔模压小炭块，具有严格的尺寸公差和优良的理化性能，以期解决炉底炉缸环状断裂和蒜头状异常侵蚀问题，使高炉一代寿命到达10－15年，该产品已用于杭钢1号高炉炉缸，三钢2号高炉炉底，昆钢5号高炉炉缸，效果良好。

超微贴片模压电感的研发

随着微电子技术、半导体器件技术的快速发展,要求功率元件的性能需要不断提升,模压电感作为未来高性能的磁性元件发展方向之一,被广泛使用在1C供电和DC-DC模块。本文较详细介绍了超微模压电感的设计开发和制造工艺,并和同行的产品进行对比分析,相同尺寸同等规格下,饱和电流性能提升约15%。

Near-net shaped Al/SiCP composites via vacuum-pressure infiltration combined with gelcasting

To solve the problem of difficult machining, the near-net shaped Al/SiCP composites with high volume fraction of SiC particles were fabricated by vacuum-pressure infiltration. The SiCP preform with a complex shape was prepared by gelcasting. Pure Al, Al4Mg, and Al4Mg2Si were used as the matrices, respectively. The results indicate that the optimal parameters of SiCP suspension in gelcasting process are pH value of 10, TMAH content of 0.5 wt.%, and solid loading of 52 vol.%. The Al matrix alloyed with Mg contributes to improving the interfacial wettability of the matrix and SiC particles, which increases the relative density of the composite. The Al matrix alloyed with Si is beneficial to inhibiting the formation of the detrimental Al4C3 phases. The Al4Mg2Si/SiCP composite exhibits high relative density of 99.2%, good thermal conductivity of 150 W·m^-1·K^-1, low coefficient of thermal expansion of 10.1×10^-6 K^-1, and excellent bending strength of 489 MPa.

Simulation study on fluctuant flow stress scale effect

Crystal plasticity theory was used to simulate upsetting tests of different dimensions and grain size micro copper cylinders in this study on the fluctuant flow stress scale effect. Results showed that with the decrease of billet grain quantity, flow stress fluctuation is not always increased, but there is a maximum. Through this study, the fluctuant flow stress scale effect can be understood deeper, and relevant necessary information was obtained for further prediction and control of this scale effect and to design the microforming process and die.

An extrusion-shear-expanding process for manufacturing AZ31 magnesium alloy tube

A new severe plastic deformation method for manufacturing tubes made of AZ31 magnesium alloy with a large diameter was developed,which is called the TCESE(tube continuous extrusion−shear−expanding)process.The process combines direct extrusion with a two-step shear−expanding process.The influences of expanding ratios,extrusion temperatures on the deformation of finite element meshes,strain evolution and flow velocity of tube blanks during the TCESE process were researched based on numerical simulations by using DEFORM-3D software.Simulation results show that the maximum expanding ratio is 3.0 in the TCESE process.The deformation of finite element meshes of tube blanks is inhomogeneous in the shear−expanding zone,and the equivalent strains increase significantly during the TCESE process of the AZ31 magnesium alloy.A extrusion temperature of 380°C and expanding ratio of 2.0 were selected as the optimized process parameters from the numerical simulation results.The average grain size of tubes fabricated by the TCESE process is approximately 10μm.The TCESE process can refine grains of magnesium alloy tubes with the occurrence of dynamic recrystallization.The(0001)basal texture intensities of the magnesium alloy tube blanks decrease due to continuous plastic deformation during the TCESE process.The average hardness of the extruded tubes is approximately HV 75,which is obviously improved.

Influence of dynamic recrystallization on microstructure and mechanical properties of welding zone in Al-Mg-Si aluminum profile during porthole die extrusion

The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and simulation.The grain morphology was observed by means of electron backscatter diffraction(EBSD)technology.The results show that,at low ram speeds,increasing the ram speed caused an increase in DRX fraction due to the increase of temperature and strain rate.In contrast,at high ram speeds,further increasing ram speed had much less effect on the temperature,and the DRX faction decreased due to high stain rates.The microhardness and fraction of low angle boundaries in the welding zones were lower than those in the matrix zones.The grain size in the welding zone was smaller than that in the matrix zone due to lower DRX fraction.The decrease of grain size and increase of extrudate temperature were beneficial to the improvement of microhardness.

A data-driven early micro-leakage detection and localization approach of hydraulic systems

Leakage is one of the most important reasons for failure of hydraulic systems.The accurate positioning of leakage is of great significance to ensure the safe and reliable operation of hydraulic systems.For early stage of leakage,the pressure of the hydraulic circuit does not change obviously and therefore cannot be monitored by pressure sensors.Meanwhile,the pressure of the hydraulic circuit changes frequently due to the influence of load and state of the switch,which further reduces the accuracy of leakage localization.In the work,a novel Bayesian networks(BNs)-based data-driven early leakage localization approach for multi-valve systems is proposed.Wavelet transform is used for signal noise reduction and BNs-based leak localization model is used to identify the location of leakage.A normalization model is developed to improve the robustness of the leakage localization model.A hydraulic system with eight valves is used to demonstrate the application of the proposed early micro-leakage detection and localization approach.

Numerical and physical simulation of new SPD method combining extrusion and equal channel angular pressing for AZ31 magnesium alloy

A new serve plastic deformation(SPD) including initial forward extrusion and subsequent shearing process(ES) was proposed.The influence of the ES forming on the grain refinement of the microstructure was researched.The components of ES forming die were manufactured and installed to Gleeble1500D thermo-mechanical simulator.The microstructure observations were carried out on the as-extruded rods(as-received) and ES formed rods.From the simulation results,ES forming can increase the cumulative strain enormously and the volume fraction of dynamic recrystallization.From the physical modeling results,the microstructures can be refined.

Progress in Pressure Swing Adsorption Models During the Recent 30 Years

The pressure swing adsorption (PSA) models discussed here are divided into three categories: partialdifferential equation model, electrical analogue model and neural network model. The partial differential equationmodel, including equilibrium and kinetic models, has provided an elementary viewpoint for PSA processes. Usingthe simplest equilibrium models, some influential factors, such as pressurization with product, incomplete purge,beds with dead volume and heat effects, are discussed respectively. With several approximate assumptions i.e.,concentration profile in adsorbent, 'frozen' column, symmetry and heat effects of bed wall, the more complexkinetic models can be simplified to a certain degree at the expense of a limited application. It has also been foundthat the electrical analogue model has great flexibility to handle more realistic PSA processes without any additionalhypothesis.

Parametric analysis of mixed lubrication characteristics in work zone of strip rolling

A theoretical model for mixed lubrication with more accurate contact length has been developed based on the average volume flow model and asperity flattening model,and the lubricant volume flow rate and outlet speed ratio are determined by integrating differential equations based on rolling parameters.The lubrication characteristics at the roll-strip interface with different surface roughness,rolling speed,reduction and lubricant viscosity are analyzed respectively.Additionally,the average volume flow rates of lubricant under different rolling conditions are calculated and used to explain the change rule of lubrication characteristics.The developed scheme is able to determine the total pressure,lubricant pressure,film thickness and real contact area at any point within the work zone.The prediction and analysis of mixed lubrication characteristics at the interface is meaningful to better control the surface quality and optimize the rolling process.

High-Speed Numeral Filter in Impulse Voltage Measurement

Since the CPU of embed system has some limitation in operating speed, a new filter was put forward which implemented mountain template convolution by performing rectangle template convolution two times. It can obtain time and frequency localization with computational complexity greatly reduced. This algorithm was applied to lightning waveforms (include chopped waveforms) parameter calculation. It simplifies the computation and the results pretreated by this algorithm are in accord with IEC1083-2 completely. It was applied in embed system successfully. Its capability in frequency restraining was researched. The validity of the algorithm was proved in theory when processing lightning waves. The standard sources and the processing results are consistent completely.

Settlement monitoring system of pile-group foundation

In order to realize information construction on settlement of pile-group foundation of Sutong Bridge, the monitoring instruments of high-precision micro-pressure sensor and hydrostatic leveling and settlement profiler were integrated synthetically. A set of practical multi-scale monitoring system on settlement of super-large pile-group foundation in deep water was put forward. The reliable settlement results are obtained by means of multi-sensor data fusion. Finite element model of pile-group foundation is established. By analysis of finite element simulated calculation of pile-group foundation, rules of settlement and uneven settlement obtained by monitoring and calculation results are coincident and the absolute error of settlement between them is 4.7 mm. The research shows that it is reasonable and feasible to monitor settlement of pile-group foundation with the system, and it can provide a method for the same type pile-group foundation in deep water.

Effects of microcracks on the poroelastic behaviors of a single osteon

It has been suggested that microcracks do play a key role in the triggering of the bone remodeling process.In order to evaluate the influence of microcracks on the poroelastic behaviors of an osteon,a finite element model is established and investigated by using the Comsol Multiphysics software.The findings show that the presence of a microcrack in the osteon wall strongly modifies(enlarges)its local fluid pressure and velocity.Especially,the pressure and velocity amplitudes produced in the microcracked region are larger than those of the non-cracked region.Thus,this study can also be used for proposing a likely mechanism that bone can sense the changes of surrounding mechanical environments.

Finite element analysis of micropipette aspiration considering finite size and compressibility of cells

Micropipette aspiration(MA) is widely applied in cell mechanics, however, at small deformations a common model corresponding to the MA is the half-space model wherein the finite cell size and cell compressibility are neglected. This study extends the half-space model by accounting for the influence of cell geometry and compressibility(sphere model). Using a finite element analysis of cell aspiration into a micropipette, an elastic approximation formula of the aspirated length was derived for the sphere model. The approximation formula includes the geometry parameter of the sphere model(ζ = R/a, R is the radius of the cell, and a is the inner radius of the micropipette) and the Poisson's ratio v of the cell. The results indicate that the parameter and Poisson's ratio v markedly affect the aspirated length, particularly for small and v. When ζ→∞ and v→0.5,the approximation formula tends to the analytical solution for the half-space model. In the incompressible case(v = 0.5), within the general experimental range(ζ varying from 2 to 4), the difference between the analytical solution and the approximate one is significant, and is up to 29% of the approximation solution when ζ= 2. Additionally, parametere was introduced to evaluate the error of elastic moduli between the half-space model and sphere model. Based on the approximation formula, the ζ thresholds, beyond which e becomes larger than 10% and 20%, were derived.