响应面法优化固定化荧光假单胞菌磷脂酶B的研究

以脱胶油磷含量为响应值,采用响应面法和Central-Composite设计对制备固定化荧光假单胞菌磷脂酶B(PfPLB)主要工艺参数(海藻酸钠浓度、壳聚糖浓度和加酶量)进行了优化,并且采用回归分析拟合了三个固定化因子与响应值(磷含量)的回归模型.该模型预测最佳的固定化Pf-PLB条件为:海藻酸钠3%,壳聚糖1.14%,加酶量1000 U/kg.研究固定化Pf-PLB的酶学性质,结果表明其最适反应温度为40℃,比游离酶提高15℃;最适反应pH为5.5,比游离酶降低1个pH单位.固定化Pf-PLB具有较好的酶活稳定性,连续反应6次,其相对活性为初始值的51.6%,显示出良好的应用前景.     

A SINGLE CHANNEL ON/OFF MODEL WITH TCP-LIKE CONTROL

We model behavior of a TCP-like source transmitting over a single channel to a server that processes work at a constant rate τ. Transmission by the source follows an on/off mechanism. When the overall load in the system is below a critical constant γ, transmission rates increase linearly but when the load exceeds γ, then transmission rates decrease geometrically fast. We study the system by means of an embedded Markov chain, which gives the buffer content at the start of transmissions. Attention is paid to the time necessary to transmit a file of size L and both the tail behavior and expectation of the distribution of file transmission time are considered.     

Reliability of Supply Between Production Lines

ABSTRACT

We compare four strategies for ensuring a reliable just-in-time supply from a seat production line, which is prone to machine failure, to a car assembly line, which is assumed to operate at a constant speed over single shifts. The strategies are as follows: holding buffer stock; duplication of the least reliable machine; duplication of the production line as a stand-by; and running two production lines concurrently. Times between machine failures are assumed to have independent exponential distributions. A general distribution of repair times is allowed for by using phase-type representations. We show the stationary distribution for these models, and compare stationary distributions with average times within levels over shifts conditional on all machines working at the start of a shift. We compute moments of sojourn times within an arbitrary subset of states, which are relevant when cost is a non-linear function of downtime. We use first passage time results to obtain probabilities of line failure within a shift, and use these results to compare the four strategies.     

A minimum asymptotic mean squared error controller for an IMA(1,1) noise process with a starting offset, and its resetting design

In a discrete-part manufacturing process, the noise is often described by an IMA(1,1) process and the pure unit delay transfer function is used as the feedback controller to adjust it. The optimal controller for this process is the well-known minimum mean square error (MMSE) controller. The starting level of the IMA(1,1) model is assumed to be on target when it starts. Considering such an impractical assumption, we adopt the starting offset. Since the starting offset is not observable, the MMSE controller does not exist. An alternative to the MMSE controller is the minimum asymptotic mean square error controller, which makes the long-run mean square error minimum.Another concern in this article is the un-stability of the controller, which may produce high adjustment costs and/or may exceed the physical bounds of the process adjustment. These practical barriers will prevent the controller to adjust the process properly. To avoid this dilemma, a resetting design is proposed. That is, the resetting procedure in use of the controller is to adjust the process according to the controller when it remains within the reset limit, and to reset the process, otherwise.The total cost for the manufacturing process is affected by the off-target cost, the adjustment cost, and the reset cost. Proper values for the reset limit are selected to minimize the average cost per reset interval (ACR) considering various process parameters and cost parameters. A time non-homogeneous Markov chain approach is used for calculating the ACR. The effect of adopting the starting offset is also studied here.     

基于B/S高职院校实验教学系统的分析与设计

针对传统实验教学模式存在的弊端,提出将计算机信息技术应用于高职实验教学之中,建立一种自主性、个性化的开放式实验教学模式,在此基础上分析和设计基于B／S的开放式实验教学系统,并对其进行评价和效果分析。     

作为体制的艺术——浅析比格尔的《先锋派理论》

比格尔以马克思在《〈政治经济学批判〉导言》中所揭示的两种方法为基础,从艺术体制角度对艺术自律这个范畴进行了批判性的考察。他认为,艺术自律乃是资产阶级社会的范畴,其普遍有效性是动态地、历史地形成的。它属于观念性艺术体制的一种表现形式。唯美主义将艺术自律推到高峰,而先锋派艺术则试图通过推翻艺术体制来重新组织新的生活实践。实际上,比格尔继承了法兰克福学派的批判传统:批判工具理性、商品拜物教、技术至上对现实生活的异化。所以,从某种程度上来说,唯美主义和先锋派所拒绝的并不是生活本身,而是资产阶级社会庸常的异化生活。悖谬的是:先锋派的艺术实践最终也被资产阶级意识形态所同化。     

我国B股市场弱式有效的实证检验

运用国内学者对我国证券进行实证检验时最常用的游程检验,自相关检验以及方差比检验方法,对B股市场是否达到弱式有效进行了实证分析。检验结果显示,上海B股市场自1998年开始达到弱式有效,而深圳B股市场则自2000开始达到弱式有效,两地市场在达到弱式有效的时间上存在差异,且弱式有效的稳定性也不同。     

智能温度采集系统研究与设计

研究内容是接触式温度采集,即多点智能温度采集系统。选择使用51单片机作为主控制器,采用DS18B20温度传感器,通过nRF24L01无线通讯模块进行远程通信,并通过LCD1602液晶显示模块显示采集结果,通过按键键盘进行人机交互,单片机作为核心控制器件,可以同时对多路温度进行测量并进行轮流显示,达到智能测量的目的。该系统可以多点对温度参数进行采集,并通过无线模块将采集到的各节点温度发送到控制中心(接收端),从而实现了环境温度的测量,解决了手动勘测时温度偏差大,耗时耗力但效率低下的问题。     

连云港保税物流中心（B型）发展现状及思路

从连云港保税物流中心（B型）发展现状着手,对其相关业务进行了分析,认为它凭借独特的区位优势,依托海港、新亚欧大陆桥,能加快形成沟通海外、连接华东、辐射中西部的区域现代物流网,进而全面提高东桥头堡的综合服务能力和经济辐射功能,探索了保税物流中心的发展策略。