双分型面注射模具设计研究

分析注射模具的分型面作用,将双分型面注射模具设计分为:点浇口结构双分型面注射模具、侧抽芯结构双分型面注射模具、顺序分型结构双分型面注射模具等3类.结合生产实例分析双分型面注射模具中移动板的移动距离控制、移动的动力来源及分型面开模顺序等关键技术,以优化注射模具结构,提高经济效益.     

Catalytic conversion of palm oil to fuels and chemicals

The conversion of palm oil to hydrocarbons using a shape selective zeolite catalyst is reported in this work. Palm oil was passed over HZSM-5 catalyst in a fixed bed micro-reactor and the reactor was operated at atmospheric pressure, a temperature range of 360 to 420°C and weight hourly space velocity (WHSV) of 2 to 4 h^?1. The main objective was to study the effect of reaction temperature and oil space velocity on the conversion and selectivity of gasoline range hydrocarbons. The results show that 40 to 70wt% of the palm oil can be converted to aromatics and hydrocarbons in the gasoline, diesel and kerosene range, light gases, coke and water. The maximum gasoline range hydrocarbons yield of 40wt% of total product formed was obtained at 400°C and 2 h^?1 space velocity.     

Effects of alkylated-chitosan–DNA nanoparticles on the function of macrophages

Chitosan could form nanoparticles with DNA through electrostatic interaction, and hence protect the DNA from enzymatic degradation. Numerous studies have been working on modifying chitosan aiming at improving its transgenic efficacy. While the modification of chitosan with alkyl group has been shown to significantly improve the cell transfection efficiency, little is known about its impact on its biocompatibility. The current study was performed to investigate the impact of alkylated-chitosan/DNA nanoparticles on the function of the murine macrophage through observing its phagocytic activity and production of pro-inflammatory cytokines (IL-1β, IL-6, IL-10, IL-12 and TNF-α). Our results demonstrated that the alkylated-chitosan/DNA nanoparticles at the concentration of 20 μg/ml DNA content had no significant impact on the production of cytokines and phagocytic activity of the macrophages as compared with the unmodified chitosan/DNA nanoparticles and negative control even after 24 h co-incubation. It suggested that the modification of chitosan with alkyl group should not have negative impact on the function of the macrophages.     

Investigation of strain transfer to a sensor protection system embedded in concrete using finite element analysis

Optical fibre-based sensor systems are being used increasingly in civil engineering applications where structural integrity monitoring is of interest or concern. This paper reports on an optimisation scheme for an optical fibre-based sensor protection system designed to protect and enhance the strain-transfer characteristic when it is embedded in concrete. The sensor protection system consisted of a stainless steel tube with specified flange designs. Three flange designs were considered: disc, cone and inverted cone. Non-linear finite element analysis incorporating contact logic was performed to select and optimise the shape and dimensions of the flange. The analysis showed high stress concentrations in the vicinity of the flanges. However, this effect was localised and was not transmitted to the intended location of the sensor. The results showed that all three flange designs were effective but the 5 mm diameter disc-shaped flange gave the best results in terms of the magnitude and symmetry of the shear stress at the tube-concrete interface.     

磁过滤真空弧源沉积C/C多层复合膜的结构和力学性能研究

采用磁过滤直流阴极真空弧源沉积技术在不锈钢基体表面制备了C/C多层复合膜,通过X射线光电子能谱、Raman光谱对薄膜的结构进行表征;C/C多层膜大气下的摩擦损性能在销盘式摩擦磨损试验机上进行;用洛氏压痕法研究了薄膜与基体的结合强度.结果表明：C/C多层复合膜为类金刚石结构.它与SiC球大气下的摩擦系数为0.10左右,其摩损性能由于多层膜的引入而显著提高.Ti过渡层的引入显著提高了膜基结合力.     

Analysis and design of ribbon cables for high‐speed digital applications

Ribbon cables have been widely used as subsystem interconnections in a large number of digital systems, because they can convey numerous bits of a digital signal simultaneously. In this article, finite difference and finite difference time domain (FDTD) methods are used to analyze and optimize the electrostatic analysis design of ribbon cables, and measurements are used to verify the numerical results. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 148–158, 2002.     

Trans fatty acids in adipose tissue of French women in relation to their dietary sources

This study reports the fatty acid composition of subcutaneous adipose tissue in French women with special emphasis on the content of trans fatty acids originating from two main dietary sources, ruminant fats and partially hydrogenated vegetable oils (PHVO). Adipose tissue trans fatty acid levels from 71 women, recruited between 1997 and 1998, were determined using a combination of capillary gas chromatography and silver nitrate thin-layer chromatography. Results indicate that on average cis monounsaturates accounted for 47.9% of total fatty acids, saturates for 32.2%, and linoleic acid for 14.4%. Cis n−3 polyunsaturates represented only 0.7%. Total content of trans fatty acids was 2.32±0.50%, consisting of trans 18∶1 (1.97±0.49%), trans 18∶2 (0.28±0.08%), and trans 16∶1 (0.06±0.03%). Trans 18∶3 isomers were not detectable. The level of trans fatty acids found in adipose tissue of French women was lower than those reported for Canada, the United States, and Northern European countries but higher than that determined in Spain. Therefore, trans fatty acid consumption in France appears to be intermediate between that of the United States or North Europe and that of Spain. Based on the equation of Enig et al., we estimated the mean daily trans 18∶1 acid intake of French women at 1.9 g per person. The major trans 18∶1 isomer in adipose tissue was Δ11trans, as in ruminant fats. Estimates of relative contribution of trans fatty acid intake were 55% from ruminant fats and 45% from PHVO. This pattern contrasts sharply with those established for Canada and the United States where PHVO is reported to be the major dietary source of trans fatty acids.     

氧化铜矿浮选研究进展

详细评述了氧化铜矿的浮选方法与工艺及浮选药剂研究进展,指出强化硫化过程、硫化质量和寻找具有高度选择性的捕收剂是其重要的研究方向     

Linear and nonlinear optical properties of RF sputtered (Pb,La)(Zr,Ti)O<Subscript>3</Subscript> ferroelectric thin films

Linear and nonlinear optical properties of (Pb,La)(Zr,Ti)O₃ (PLZT) ferroelectric thin films were presented in this paper. The PLZT ferroelectric thin films have been in situ grown on quartz substrates by radio-frequency (RF) magnetron sputtering at 650 °C. Their crystalline structure and surface morphologies were examined by X-ray diffraction and atomic force microscopy, respectively. It can be found that the PLZT thin films exhibit well-crystallized perovskite structure and good surface morphology. The fundamental optical constants (the band gap energy, linear refractive index, and linear absorption coefficient) were obtained through the optical transmittance measurements. A Z-scan technique was used to investigate the optical nonlinearity of the PLZT thin films on quartz substrates. The films display the strong third-order nonlinear optical effect. A large and negative nonlinear refractive index n ₂ is determined to be 1.21 × 10⁻⁶ esu for the PLZT thin films. All results show that the PLZT ferroelectric thin films have potential applications in optical limiting, switching, and modulated-type optical devices.     

Retrieval of daily evolution of soil moisture from satellite-derived land surface temperature and net surface shortwave radiation

Soil moisture is a key parameter in water balance, and it serves as the core and link in atmosphere–vegetation–soil–groundwater systems. Soil moisture directly affects the accuracy of the simulation and prediction conducted by hydrological and atmospheric models. This article aims to develop a new model to retrieve the daily evolution of soil moisture with time series of land surface temperature (LST) and net surface shortwave radiation (NSSR). First, for the time series of soil moisture, LST and NSSR daytime data were simulated by the common land model (CoLM) with different soil types in bare soil areas. Based on these data, the variations between soil moisture and LST-NSSR during the daytime with different soil types were analysed, and a plane function was used to fit the daily evolution of soil moisture and the time series of LST and NSSR data. Further study proved that the coefficients of the soil moisture retrieval model are not sensitive to soil type. Then, a relationship model between the daily evolution of soil moisture and the time series of LST-NSSR was developed and validated using the data simulated by CoLM with different soil types and different atmospheric conditions. To demonstrate the feasibility of the soil moisture retrieval method proposed in this study, it was applied to the African continent with data from the METEOSAT Second Generation Spinning Enhanced Visible and Infrared Imager (MSG–SEVIRI) geostationary satellite. The results show that the variation of soil moisture content can be quantitatively estimated directly by the method at the regional scale with some reasonable assumptions. This study can provide a new method for monitoring the variation of soil moisture, and it also indicates a new direction for deriving the daily variation of soil moisture using the information from the time series of the land surface variables.