面向轿车方案设计决策的OLAP和DM应用研究

结合工程应用从支持轿车方案设计决策的角度深入研究了OLAP关键的分析操作，建立了联机分析数据结构模型。提出了决策树和关联分析两种数据挖掘方法，并给出了两种数据挖掘方法在轿车方案设计决策的应用示例。     

Expansion characteristics of an anaerobic fluidized bed reactor with internal biogas production

More realistic dynamic bed‐expansion experiments using a three‐phase anaerobic fluidized bed reactor (AFBR) with and without internal biogas production were conducted for the establishment of correlation equations for the mean volume ratio of wakes to bubbles (k). A predictive model was also developed for the expansion characteristics of the three‐phase AFBR with internal biogas production. The predicted bed‐expansion heights (H_GLS) deviated by only ±10% from the experimental measurements for the three‐phase AFBR. According to the modeling results, if a three‐phase AFBR is loaded into a carrier with low specific gravity (dry density of carrier, ρ_md = 1.37 g cm^?3; wet density of carrier, ρ_mw = 1.57 g cm^?3) and operated at a high superficial liquid velocity (u_l = 4.0 cm s^?1), the ratio of H_GLS to H_LS at a high superficial gas velocity (u_g = 1.5 cm s^?1) can reach as high as 271%. A higher fluidized‐bed height has a greater effect on the bed‐expansion behavior because of the decrease in liquid pressure (surrounding gas bubbles) along the fluidized‐bed height. From parametric sensitivity analyses, H_GLS is most sensitive to the parameter reactor width (X), especially within a small ΔX/X₀ range of ±10%; sensitive to ρ_mw, diameter of the carrier, ρ_md and total mass of carrier and least sensitive to u_l, biofilm thickness and u_g. Copyright © 2005 Society of Chemical Industry     

Penicillin G acylase purification with the aid of high-throughput screening approach

Penicillin G acylase (PGA) is one of the most important enzymes for the production of semi-synthetic β-lactam antibiotics and their key intermediates. Purification of penicillin G acylase from fermentation broth with the aid of high-throughput screening (HTS) process has been examined in this study. We used a microtiter-plate based on screening method to find appropriate purification conditions for the target protein. The screening method is based on a 96-well plate format, and different matrices and conditions (pH, salt concentration and type) were tested. Through analyses of all pooled fractions (flow-through and elution) we gained appropriate information to choose the best performing matrix and buffer conditions for upscaling. After an upscaled purification step the second unit operation is screened in the similar way and parameters for this operation can be chosen. The purification parameter of purified PGA at the small-screen and upscaling levels were measured, respectively. The results indicate that high-throughput progress based on a 96-well plate is a flexible and efficient paradigm for recombinant protein purification.     

聚醚润滑剂的特点及应用

概括了聚醚润滑的主要性能，简要叙述了各种聚醚的主要应用实例和国内外研究发展现状，聚醚的应用领域将逐步扩大。     

基于OMAP5912视频监控终端的软件设计

视频信息的采集、压缩、传输是视频监控系统的核心环节,它决定了视频监控系统的各个性能指标。采用数字化的传感器和高性能的视频压缩算法可以克服传输过程中的干扰,增大系统的容量,提高监控服务器的安全性。阐述了基于TI公司OMAP5912平台的视频监控系统终端的软件设计。     

低能入射Si与Si(001)2×1重构表面相互作用过程的分子动力学模拟

利用Tersoff势函数,对300K时初始入射动能为0.03eV的单个Si原子从6个不同位置轰击Si(001)2×1重构表面的动力学过程进行了模拟.分析了入射Si原子的动能变化、势能变化以及其运动轨迹.结果表明:入射原子与表面原子相互作用几个皮秒后即可进入稳定位置,其与基底原子的结合能最大可以达到2.99eV;从位置1,2,3,4入射的原子不能使基底表面的二聚体键断开,而从位置5和位置6入射时,表面二聚体键的断开在入射原子与基底表面原子发生相互作用几十飞秒后即可完成.     

一种基于认知无线电的动态频谱接入MAC方案

在传统的无线通信系统中,频谱的分配是固定的。但是由于通信过程的突发性,这些频谱的使用率很低。另一方面,随着无线通信和多媒体的高速发展和广泛应用,无线频谱资源日趋紧张。如何提高频谱利用率已经成为迫切需要解决的问题。一种可行的思路是把这些授权频谱向未授权用户开放,未授权用户采用动态频谱接入技术,在不对授权用户造成干扰的前提下使用频谱。本文以认知无线电技术(Cognitive Radio,CR)为基础,提出了一种基于CR的动态频谱接入MAC方案(CR-Ad Hoc-MAC)。该方案允许未授权用户自适应地选取可用带宽,实现了动态频谱接入,有效地提高了频谱利用率。     

Improvement of the high energy ball-milling preparation procedure of CO tolerant Pt and Ru containing catalysts for polymer electrolyte fuel cells

Ball-milling has been used to prepare performing CO tolerant polymer electrolyte fuel cell anode catalysts that contain Pt and Ru. The catalyst precursors are obtained by milling together Pt, Ru and a dispersing agent in the atomic ratio 0.5, 0.5 and 4.0. This precursor is not easily recovered after milling because it sticks to the walls of the vial and on the grinding balls. However, the precursor is recovered as a powder when a process control agent (PCA) is added during the milling step. Various PCAs have been used. The PCA should not interfere with the electrocatalytic activity of the catalysts obtained by leaching the precursor. The best preparation of catalyst precursors are obtained by milling: (i) Pt, Ru and Al (dispersing agent) in the atomic ratio 0.5, 0.5, 4.0 + 10 wt% NaF (PCA) or (ii) Pt , Ru and MgH₂ in the 0.5, 0.5, 4.0 atomic or molecular ratio. In this case, MgH₂ plays at the same time the role of a dispersing agent and that of a PCA. The catalysts are obtained by leaching Al and NaF in (i) or MgH₂ in (ii). The CO tolerance of these catalysts is equivalent to that of Pt_0.5Ru_0.5 Black from Johnson Matthey. The ball-milled catalysts have a surface area comprised between 30 and 44 m² g^–1. As-prepared catalysts are mainly made of metallic Pt and metallic plus oxidized Ru. After fuel cell tests, Pt is completely metallic while the oxidized Ru content decreases but does not disappear. These catalysts are composed of particles with crystallites of two different sizes: in (i) nanocrystallites (4 nm) that contain essentially Pt alloyed with Al and perhaps some Ru, and larger (30 nm) crystallites that contain essentially Ru; in (ii) Pt nanocrystalline particles that may contain some Ru and larger particles that contain essentially either Ru or Pt.     

客车车身的模态分析

以某客车企业开发的城市客车车身骨架为研究对象,利用试验模态分析理论研究客车车身振动,采用锤击法对其进行模态测试,获得结构的模态频率、阻尼、振型等模态参数,为改进该客车的车身结构设计提供试验依据和改进思路。