An approach to estimate body dimensions through constant body ratio benchmarks

Building a new anthropometric database is a difficult and costly job that requires considerable manpower and time. However, most designers and engineers do not know how to convert old anthropometric data into applicable new data with minimal errors and costs (Wang et al., 1999). To simplify the process of converting old anthropometric data into useful new data, this study analyzed the available data in paired body dimensions in an attempt to determine constant body ratio (CBR) benchmarks that are independent of gender and age. In total, 483 CBR benchmarks were identified and verified from 35,245 ratios analyzed. Additionally, 197 estimation formulae, taking as inputs 19 easily measured body dimensions, were built using 483 CBR benchmarks. Based on the results for 30 recruited participants, this study determined that the described approach is more accurate and cost-effective than alternative techniques.     

Formaldehyde-, Benzene-, and Xylene-Sensing Characterizations of Zn–W–O Nanocomposite Ceramics

Zn–W–O nanocomposite ceramics with the whole concentration range ( W at.%=0%, 1%, 5%, 25%, 50%, 75%, 95%, 99%, and 100%) have been fabricated by the sol–gel method, starting from zinc acetate dihydrate, ammonium tungstate, monoethanolamine (MEA), and anhydrous ethanol. Nanocomposites, that were sintered at 650°C in a conventional oven for 120 min were ultrasonically emulsified and coated on alumina ceramic tubes by dip coating. The microstructure and morphology of nanocomposites were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM), respectively. The resistance and sensitivities to poisonous volatile organic compounds (PVOCS) were investigated on the static testing chamber. The XRD analysis of nanocomposites revealed the appearance of ZnWO₄ with a monoclinic structure in the whole concentration range (1–99 at.%). The FESEM results showed that as-prepared nanocomposites were composed of almost spherical particles with size range from 200 to 300 nm. Gas-sensing properties of Zn–W–O nanocomposites ceramics, to formaldehyde, benzene, and xylene, were detected. The results showed that the ZnWO₄ phase with high resistance almost did not respond to PVOCS. The appropriate amounts of ZnWO₄ in ZnO-rich samples and in WO₃-rich samples lend themselves to enhancement of gas-sensing properties to PVOCS. The effect of ZnO, WO₃, and ZnWO₄ with a scheelite structure as solid acidic/alkaline catalysts on gas-sensing property is also discussed.     

模具行业信息

<正>新兴战略性产业将牵引中国模具产业增长在当前"后危机时代",世界各主要发达国家和经济体均选择了不同的新兴产业作为突破口。奥巴马政府将新兴产业重点放在新能源和环保产业上,欧盟重在将"绿色技术"和其他高端技术提升至全球领先水平,日本把重点产业放在新型汽车、低碳产业、新能源(太阳能)等新兴产业,韩国将绿色技术、尖端产业融合、高附加值服务等三大领域共17项新兴产业确定为重点产业。尽管各国的政治经济体制不同,但无论是以市场经济为主导的欧美国家,还是以政府主导型经济为主的东亚国家和地区,政府大多对未来需要重点发展的新兴产业给予必要的培育和扶持。如今,中国政府已     

基于模板匹配的二维图自动生成算法研究

基于模板匹配的思想,对二维图的自动生成算法进行了研究。首先将模板和待标注三维模型的点、线、面信息以及几何结构和拓扑结构以属性图的数据结构方式进行存储,通过面的广度优先搜索和边的广度优先搜索对存储的2个属性图进行匹配,再读取模板二维图上的标注等信息,利用二维图和三维模型的关联性和属性图匹配结果,对待标注三维模型进行自动标注,包括尺寸标注、表面粗糙度标注、形位公差标注等信息。     

MA-SPS-HIP技术制备钒合金的工艺探索

探索了机械合金化-放电等离子体烧结-热等静压(MA-SPS-HIP)技术制备V-4Cr-4Ti-1.8YH2合金的工艺流程,并对其在1000~1200℃下真空退火后的性能进行了测试。XRD和SEM分析表明,球磨50 h以上基本上可以达到机械合金化的目的。材料的拉伸测试表明V-4Cr-4Ti-1.8YH2合金有良好的力学性能,并且在退火温度为1100℃真空退火后综合力学性能达到最佳。合金材料微观组织分析表明,V合金的晶粒尺寸大多在0.5μm以下,YH2在烧结过程中转变成了Y2O3,以小于50 nm的粒子弥散分布在基相之中。     

Study on the surface roughness of ceramic shells and castings in the ceramic shell casting process based on expandable pattern

A method to form a thin smooth film of wax on the surface of the foam pattern was proposed by introducing the molten wax in this work. Organic smoothing coatings for the foam pattern were also prepared and their effects on the surface roughness of the foam patterns, shells and castings were investigated. Effects of the facecoat slurry used to fabricate ceramic shells on the surface roughness of the shells and castings were studied. The analysis of results indicates that the surface smoothing coatings and the wax smoothing film both greatly decreased the surface roughness of ceramic shells and castings from 3.2-6.3 μm to 0.8-2.5 μm (Ra), and the surface roughness of shells and castings would be improved if the facecoat slurry is prepared with finer filler materials.     

The effect of top and bottom lids on natural convection inside a vertical cylinder

Natural convection experiments inside a vertical cylindrical cavity were performed for Rayleigh numbers of 1.08 × 10¹⁰–2.11 × 10¹³ and for four different geometrical arrangements: both-open (pipe-shape), bottom-closed (cup-shape), top-closed (cap), and both-closed (cavity) cylinders. A copper electroplating system was employed for the measurements of heat transfer rates using analogy concept. The lids used to close top or bottom were adiabatic; i.e. inactive surfaces in the electrodeposition experiments. The bottom-closed cavity showed the highest heat transfer rates and then followed both-closed, both-open, top-closed ones in both laminar and turbulent flows. The results were in satisfactory agreements with the existing correlations developed for similar geometrical configurations and the empirical correlations were derived. The numerical simulations were carried out using the FLUENT 6.2 to explain the measured results. The analysis of the streamline and the local Nusselt number gave explanations for the observation.     

Enhanced electrochemical performance of solution impregnated La0.8Sr0.2Co0.8Ni0.2O3−δ cathode for intermediate temperature solid oxide fuel cells

Solution impregnated La_0.8Sr_0.2Co_0.8Ni_0.2O₃ + Gd-doped CeO₂ (LSCN + GDC) cathodes for intermediate temperature solid oxide fuel cells (IT-SOFC) are prepared and their electrochemical properties are evaluated and compared with the conventional LSCN cathodes. The results indicate that the cathode performance can be enhanced by the presence of the nanosized microstructure produced with the solution impregnation method. It is determined that the amount of LSCN loading in the LSCN + GDC composite cathode needs to be higher than 35 wt% in order to achieve a performance superior to that of the conventional LSCN cathode. The optimum amount of LSCN loading is in the range of 45-55 wt% with an activation energy near 1.32 eV for oxygen reduction. At temperatures between 600 and 750 °C, the polarization resistance of the 55 wt% LSCN loaded LSCN + GDC cathode is in the range of 1.07 and 0.08 Ω cm², which is only about one half of that for the conventional cathode.