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The finite element analysis was carried out on the piston of WWD - 0.8/10 type air compressor under the action of mechanical load stress and deformation.Using three-dimensional modeling software Solidworks to establish a simplified geometric model of piston in air compressor ,Transform the model built in the three dimensional finite element analysis software into the finite element model for analysis,Determine the method of the piston by the mechanical load and boundary conditions,Completed the stress analysis and deformation analysis of the piston under the mechanical load ,The results of analysis of the piston design optimization has important reference value.

Based on the side hole and no flange and one-step drawing part forming analysis and comparison of the process, the compound die that can complete 4 procedures -blanking, drawing , punching and trimming at in the same forming-position was synchronously designed. Production testing confirmed that there were different levels of improvements in the product quality, production efficiency and economic efficiency. This paper describes die structure, die working process, design and manufacture of main pans of die.

Error analysis of measuring instruments is a significant part in the process of measuring instruments design with which primary error factors influencing measuring accuracy can be obtained. In order to correctly analyze and evaluate the sensors errors, the influence on final measurement result caused by error factors of all parts should be taken into account. Electric error consist zero voltage error and power errors including amplitude errors, phase errors and frequency errors. It will be difficult and cost much to improve accuracy of measurement with hardware method. So error correction technology is employed to ensure system accuracy. This method not only improves accuracy effectively but also reduces manufacturing cost of measuring instruments. In addition, errors suppression technology based on error separation, error correction of the Ordinary Least Square (OLS) and negative feedback model is proposed. Improving Time­-grating displacement sensor’s measurement accuracy plays an important role in the mass production of Time-grating displacement sensor.

A kind of conductive composite material for the bipolar plate of proton-exchange membrane fuel cells (PEMFC) was fabricated by the hot-pressure molding with graphite powders and polyphenylene sulfide (PPS) resin powders. The influencing factors including PPS resin content, molding pressure and molding temperature, and temperature holding time on the conductivity, flexural strength and density of the composite were investigated. It was found that the perfect conditions for the fabrication of bipolar plate were that the PPS resin content was 25%wt, the forming pressure was 20 MPa, the mold temperature was 320°C and the holding time was 25 min.

This paper studied the effect of temperature, single surface-active agent and anionic/non-ionic surface-active agents to the viscosity of sludge-sump oil, and ditermined the optimum process conditions by orthogonal experiment. The result showed that the viscosity of sludge-sump iol reduced with the increase of temperature when below 50°C, then the viscosity decreased slowly when the temperature is above 50°C. The optimum conditions obtained by orthogonal experiment were: OP-10 0.6%, sodium dodecyl benzene sulfonate (SDBS) 0.3% and water content 35%. The viscosity reduction rate was about 98.80%.

Radiometric calibration of synthetic aperture radar (SAR) is an important work related to pixel values and the backscattering coefficient of ground targets. With a consideration of the difference between near space and spaceborne, airborne platforms, this paper proposes the radiometric calibration method which is applicable to near space platform. A radiometric calibration model of near space SAR is established, and it is analyzed and validated by experimental data.

Ceramics with the formula Ca_1-xSr_xZr₄(PO₄)₆ (x=0.4, 0.45, 0.5, 0.55) have been synthesized by coprecipitation method, an. their structures, phase transitions, thermal expansion properties have been studied by differential sanning calorimetry, scanning electron microscope, X-ray diffraction and dilatometer. The results show that Ca_1-xSr_xZr₄(PO₄)₆ ceramics sintered at 1400°C had good sintering condition. Unit cell volume basically had no change with substitution of Ca by Sr. The coprecipitation method saved energy and time. It was introduced to increase the relative density of Ca_0.5Sr_0.5Zr₄(PO₄)₆ ceramic. The coefficient of thermal expansion was about 1.447×10^-6/°C.

The determination method for analyzing trace copper in vanadium alloy by flame atomic absorption spectrometry was investigated in the paper. The sample digestion method, digestion acidity, determination conditions, matrix interferences, method precision, recovery of standard addition were investigated in detail. The method precision in RSD% was 8.6%, and the average recoveries of standard addition were from 93.9% to 95.6%. The experimental results indicated that the proposed method for determination of trace copper in vanadium alloy was simple, fast, accurate, and easy to operate, which was suitable for quality control of vanadium alloy.

The characterization in microstructure, morphology and oxidation behavior of three iron-based coatings by Supersonic Arc Spraying (HVAS), were investigated by XRD, FESEM, EDS and thermal exposure in furnace in this paper. It is indicated that the three coatings are typical layer and compact structure. The coatings are composed of Fe (s.s) phase and kinds of ferric oxides, chrome carbides and/ or intermetallic phase distributing along the interface of lamellar layers. More Cr and Ti, Al elements can alternate the diameter and morphologies of the holes, resulting from the formation of oxides, carbides and intermetallic phase. The results indicate that SXTiAlC coating shows the most excellent oxidation resistance with 2.70 mg·cm^-2 in mass gain, while that are 88.08 mg·cm^-2 and 16.64 mg·cm^-2 after 100 h thermal exposure at 800°C for LX88A and SXHCrA coatings, respectively. The oxidation behavior is discussed.

In this paper, an optimized p⁺ shielding 4H-SiC trench-gate metal-oxide-semiconductor field effect transistors (UMOSFETs) structure with floating regions is proposed. The p⁺ shielding region is moved down to gain a low device on-resistance and the floating regions are designed to improve the breakdown voltage in the proposed structure. Specific on-resistances of the proposed 4H-SiC UMOSFETs is 2.62 mΩ.cm² at V_GS=18 V and V_DS=10 V, compared with 4.77 mΩ.cm² for the conventional p+ shielding UMOSFETs structure with same breakdown voltage. The on-resistance and figure of merit (FOM = V_BR²/R_on) improve by 45.1% and 94.2%, respectively.