Study of different effect on foaming process of biodegradable bionolle in supercritical carbon dioxide

Microcellular foaming of biodegradable Bionolle in supercritical CO₂ has been produced. The effects of a series of variable factors, such as saturation temperature, saturation pressure, and depressurization time and step on the foam structures and density, were studied through measurement of density and SEM observation. The experimental results show that higher saturation temperatures lead to an increase in bulk densities; and different depressurization time and step result in different product cell morphology. In addition, at some saturation temperature, the orientation of the cells can be found in the product morphology. XRD experimental results show that the foaming treatment with SC CO₂ increased the crystallinity of Bionolle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2901–2906, 2006     

Approximate K-Median of Location Streams with Redundancy and Inconsistency

Data streams produced by positioning systems such as Global Positioning System (GPS) or RFID readers can be considered as location streams[12]. Location streams are usually generated in a distributed fashion by a large scale distributed system covering a wide range of areas. Computing on distributed location streams is both practically useful and theoretically challenging. The results of computation could be used to schedule the traffic in a metropolis to avoid traffic jam, dispatch taxis to serve the passengers more quickly and display the current position of goods in supply chain management, etc. Since location streams are usually generated with very high rate in uncertain ways over hostile environments, the collected updates of location are probably redundant and inconsistent in a wide positioning system. To process distributed location streams with redundancy and inconsistency, this paper proposes a novel method based on min-wise hash. With this method, redundant updates of distributed location streams can be effiectively filtered out, while the true location could be derived from inconsistent ones. Consequently, globally uniform samples can be obtained. Based on the uniform samples, an algorithm for computing the approximate k-median of huge number of moving objects is presented in this paper. Furthermore, it is demonstrated that sketch-based methods are not necessarily effiective in processing location streams with redundancy and inconsistency. In addition to theoretical analysis, some extensive experiments are conducted to validate the efficiency and effiectiveness of the proposed approach.     

富镁Mg_（70）（Ni_3RE）_（30）非晶合金的玻璃形成能力研究

玻璃形成能力（GFA）是判断合金非晶态结构形成的重要指标。利用甩带快冷技术制备了Mg70（Ni3RE）30（RE=La、Ce、Pr、Nd、Y）非晶合金条带（宽5 mm,厚0.2 mm）,通过差示扫描量热技术（DSC）表征了合金条带的非晶结构转变及其热稳定性。从原子尺度,对合金的原子尺寸参数（δ）、电负性差（Δx）以及原子结构参数（λ）进行了计算和分析。实验数据和理论分析结果表明：RE=Pr时,相应合金的玻璃形成能力最大,RE=Y的最小,其大小次序为：Mg70（Ni3Pr）30〉Mg70（Ni3la）30〉Mg70（Ni3Ce）30〉Mg70（Ni3Nd）30〉Mg70（Ni3Y）30,影响Mg70（Ni3RE）30非晶合金玻璃形成能力的主要因素是电负性差,原子尺寸参数和原子结构参数的作用次之。     

Longitudinal surface cracks of thin slabs

Based on the production practice of medium carbon thin slabs in the CSP plant,the reasons and influencing factors for the formation of longitudinal cracks were investigated,and some industrial measures were taken to eliminate the cracks.The results show that the efficient solutions to reduce longitudinal cracks are improving the performance of the mold powder,stabilizing the mold heat flux,and maintaining a proper taper of the mold during casting.Proper pouring temperature and secondary cooling also play...     

高速公路收费站车辆能耗研究

车辆通过高速公路收费站时,需要减速或停车缴费,当车辆较多时,容易形成排队,产生大量延误,大大削弱了车辆的运行效率,增加了车辆的能耗,同时使得车辆尾气的排放量增加,严重污染了环境。本文使用排队论知识对收费站车辆排队与疏散情况进行分析,减少车辆的排队等候时间和驶离站口所需时间,以达到减少行车能耗的目的。最后,通过一个实例给出几种收费方式下的能耗,并给出了相应的分析和建议,可为高速公路收费方式和能耗研究提供一定的参考。     

Antibacterial and corrosive properties of copper implanted austenitic stainless steel

Copper ions were implanted into austenitic stainless steel (SS) by metal vapor vacuum arc with a energy of 100 keV and an ions dose range of (0.5-8.0)×1017 cm-2. The Cu-implanted SS was annealed in an Ar atmosphere furnace. Glancing X-ray diffrac-tion (GXRD), transmission electron microscopy (TEM) and Auger electron spectroscopy (AES) were used to reveal the phase compositions, microstructures, and concentration profiles of copper ions in the implanted layer. The results show that the antibacterial property...     

简论《周易》对《汉书·艺文志》的影响

班固的《汉书·艺文志》源于刘向及其子刘歆的《七略》,是我国现存最早的目录学文献。《汉书·艺文志》中多处引用《周易》,并尊《周易》为“五经之原”,充分体现了汉初《周易》在学术界及思想界的重要地位,从中还可看出《周易》在汉初已成为儒家立论言说的理论基础及辨章学术,考镜源流的“万方之略”。     

五流大方坯中间包流场优化

针对某钢厂五流大方坯中间包3流铸坯探伤不合格率较高的问题,采用数值模拟方法,研究不同结构中间包钢液的流场。结果表明,该钢厂现使用的中间包结构不合理,近流有短路流出现,且各流差异较大,不利于去除钢液中的夹杂物和提高各流间钢液的均匀性;采用大冲击区,挡墙中墙不开孔、侧墙开4个孔,设置2个坝的中间包结构最佳;中间包结构优化后,消除了近流的短路流,中间包钢液平均停留时间达652.9 s,各流示踪剂浓度的标准差仅为0.011 9,死区体积分数也仅为21.96%,既有利于夹杂物上浮去除,也保证了各流间钢液的均匀性。     

熔体接枝与共混改性调控等规聚丙烯聚集态结构与性能

聚丙烯在应力与温度等因素作用下晶型转变而引起的物理力学性能的变化尚未得到学术界与工程界的应有重视。通过熔体自由基接枝多功能团单体、添加高熔点的聚合物和α成核剂调控其聚集态结构,有效抑制了聚丙烯在应力作用下的晶型转变,改善了聚丙烯的疲劳稳定性,有助于增加其在工程应用中的使用寿命。     

人工神经网络在改善报警系统性能中的应用

介绍了一种利用BP人工神经网络降低报警系统误报警率的有效方法。以STC89C52RC处理器为平台,在嵌入式系统中应用BP网络先对报警信息进行分析和预处理,再控制报警系统动作。该方法大大降低了报警系统因自然因素导致的误报警概率。采集了100个典型数据对BP网络进行训练,得到了适合应用目标的网络模型,现场实测误报警率几乎为0。该方法的硬件价格便宜,电路简单,是一种降低报警系统误报警率的有效方法。