一种适于企业群体模糊综合评价的改进模型

从模糊综合评价初始模型入手，分析了初始模型的缺陷及前人对其进行的改进，认为改进后的模型仍不能很好地适应群体评价的需要．本文以改进的方法为理论依据，提出了一种适于企业群体综合评价的新模型，并举例说明．     

In Vitro Characterizations of PLLA/β-TCP Porous Matrix Materials and RMSC-PLLA-β-TCP Composite Scaffolds

To develop a novel degradable poly (L-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) bioactive materials for bone tissue engineering, β-TCP powder was produced by a new wet process. Porous scaffolds were prepared by three steps, I.e. Solvent casting, compression molding and leaching stage. Factors influencing the compressive strength and the degradation behavior of the porous scaffold, e.g. Weight fraction of pore forming agent-sodium chloride (NaCl), weight ratio of PLLA: β-TCP, the particle size ofβ-TCP and the porosity, were discussed in details. Rat marrow stromal cells (RMSC) were incorporated into the composite by tissue engineering approach. Biological and osteogenesis potential of the composite scaffold were determined with MTT assay, alkaline phosphatase (ALP) activity and bone osteocalcin (OCN) content evaluation. Results show that PLLA/β-TCP bioactive porous scaffold has good mechanical and pore structure with adjustable compressive strength needed for surgery. RMSCs seeding on porous PLLA/β-TCP composite behaves good seeding efficacy, biocompatibility and osteoinductive potential. Osteoprogenitor cells could well penetrate into the material matrix and begin cell proliferation and osteogenic differentiation. Osseous matrix could be formed on the surface of the composite after culturing in vitro. It is expected that the PLLA/β-TCP porous composites are promising scaffolds for bone tissue engineering in prosthesis surgery.     

人工神经网络实现专家系统中的自动知识获取

神经网络适宜于处理具有残缺结果和含有错误成分的模式,能够在信源信息含糊、不确定、不完整,存在矛盾及假相等复杂环境中进行处理.网络所具有的自学习能力使得传统专家系统技术应用最为困难的知识获取工作转换为网络的变结构调节过程,从而大大方便了知识库中知识的记忆和提取.本文用人工神经网络中BP网络实现了专家系统中自动获取知识的功能.     

机械合金化制备β-FeSi2热电材料的研究

采用MA(Mechanical Alloying)法进行β-FeSi2热电材料的合成研究.以Fe粉(Fe>98%),Si粉(Si>99.9%)为原料,将Fe、Si 元素粉末按原子分数Fe33Si67混合,并将混合料放入高能星型球磨机进行长时间球磨.经不同的工艺进行机械合金化并取样,借助XRD、DSC等手段进行分析.研究结果表明在机械合金化大约20h以上开始形成ε-FeSi相,至机械合金化大约40h有β-FeSi2形成,随时间的延长β-FeSi2相增多.     

Vibration Control of Wind-Excited Tall Buildings Using Sliding Mode Fuzzy Control

A sliding mode fuzzy control (SMFC) is proposed to design a controller for the third-generation benchmark problem on wind-excited buildings. A distinctive feature in vibration control of large civil infrastructure is the existence of large disturbances, such as wind, earthquake, and sea wave forces. Those disturbances govern the behavior of the structure; however, they cannot be precisely measured, especially for the case of wind excitations. Since the structural accelerations are measured only at a limited number of locations without the measurement of the wind forces, the structure of the conventional control may have the feedback loop only. The general structure of the SMFC, proposed herein, is composed of a compensation part and a convergent part. The compensation part prevents the system from diverging, and the convergent part directs the system to the sliding surface. The compensation part uses not only the structural response measurement but also the disturbance measurement, so the SMFC has a feedback loop and a feedforward loop. To realize the virtual feedforward loop for the wind-induced vibration control, a disturbance estimation filter is introduced. The structure of the filter is constructed based on an autoregressive model for the stochastic wind force. This filter estimates the wind force at each time instance based on the measured structural responses and the stochastic information of the wind force. For verification of the proposed algorithm, numerical simulation is carried out on the benchmark problem for wind-excited buildings. The results indicate that the present control algorithm is efficient for reducing the wind-induced vibration.     

可编程自动化控制器(PAC)--新一代的PLC

本文介绍了新一代的可编程自动化控制器(PACs)的概念、产生背景及现状，分析了其构成方式、技术优势，最后阐述了其应用前景及发展趋势。     

Active leave behavior of members in a fault-tolerant group

With the fast development of network applications, there are more asynchronous distributed systems and more requirements for fault tolerance. Asynchrony means there is no upper bound for either message transfer or operation execution. Active replication is an effective means to enhance fault tolerant capability in distributed systems. A key component in a system is replicated and all the replicas make up of a fault-tolerant group. Members in such a group execute all client requests and then re…     

生物质谱作为SNP分型检测方法的研究

利用改良的 Miller法从人血中提取人类基因组 DNA。采用聚合酶链式反应 ( Polymerase chain reac-tion,PCR) ,对含有单核苷酸多态性 ( SNP)点的 DNA片段进行扩增 ,然后用 CIP和 Eox I去除掉 PCR体系中剩余的脱氧核糖核苷三磷酸 ( d NTP)和引物 ,最后用单碱基延伸反应获得 SNP位点处碱基类型。用基质辅助激光解吸电离 -飞行时间质谱 ( MALDI-TOFMS)或电喷雾电离 -四极杆飞行时间质谱 ( ESI-Qq TOFMS)检测延伸产物与未延伸引物间的分子量差异 ,确定该点处碱基。对不同的生物质谱检方法以及生物质谱检测方法与其它检测方法的优缺点进行了分析比较     

砂带磨削的发展及关键技术

介绍了发展砂带磨削技术的意义及砂带磨削技术的发展趋势,通过比较国内外砂带磨削技术的差距,提出了促进我国砂带磨削技术发展的关键技术,包括新型砂带研制、高端精密高效砂带磨床研制、砂带磨床标准制定等方面。     

通用异步串行通讯测试系统

介绍了一种通用异步串行接口的测试系统,该系统利用USB2.0接口与控制计算机进行通讯,设计特定的信号源向异步串行通信接口提供信源数据,同时通过产生的取数时钟取回接口回传的PCM码流数据还可送回控制计算机进行分析.