PDC钻头钻进过程的动态仿真

计算机软件模拟试验可对各种形式的PDC钻头在不同的岩层条件和钻井参数下进行试验。将井架、钻柱和钻头作为一个系统,建立了PDC钻头动力学模型,包括纵向振动、横向振动、扭转振动以及钻头与井壁碰撞模型。通过面向对象的编程方法,在Visual C6.0的环境下将模型实现为计算机软件。实例证明,仿真软件计算结果与PDC钻头实际工况吻合。利用该软件可在不同岩石性质和钻井参数下,对PDC钻头进行仿真,研究各种设计方案在钻进过程中的工作性能,进行分析对比,优选出较好的设计方案。     

淀粉/PEI共聚物的制备及在瓦楞原纸中的应用

本文以（NH4）2S2O8-NaHSO3为引发剂在一定条件下制备得淀粉／PEI共聚物。结果表明共聚物对瓦楞原纸环压强度和裂断长的提高非常有效,在添加量为1％时,环压强度指数和裂断长比空白样可分别提高11．53％和34．26％。     

SCM435热变形奥氏体连续冷却转变行为

采用Gleeble-1500热模拟机测定了SCM435冷镦钢在不同冷速下连续冷却转变的膨胀曲线,结合光学显微镜的微观组织观察,测绘了该钢热变形奥氏体连续冷却转变过程中的动态CCT曲线;研究了其连续冷却转变产物的组织形态.实验结果表明,SCM435在0.5～30℃/s冷却速率下的组织主要由铁索体+珠光体、铁索体+珠光体+贝氏体、贝氏体+马氏体、马氏体组成.     

基于相对气味活度值法的新疆大盘鸡中主要挥发性风味物质分析

采用固相微萃取和气相色谱-质谱联用技术对新疆大盘鸡中的挥发性风味物质进行萃取和分离鉴定,采用相对气味活度值法确定对新疆大盘鸡香气具有主要贡献作用和修饰作用的香气物质。结果表明：共检测出64 种挥发性风味物质,醇类和醛类物质含量所占比例较高,分别为26.9%、36.4%;柠檬醛、1-辛烯-3-醇、壬醛、己醛、β-紫罗兰酮、桉树醇、苯甲醛、D-柠檬烯、芳樟醇、β-月桂烯、辛醛、1-庚醇、庚醛及2-戊基呋喃14 种物质对新疆大盘鸡香气贡献较大;苯乙醇、苯乙醛、正己酸乙烯酯、苯甲醇、(E)-2-辛烯醛、戊醛、乙酸芳樟酯、α-蒎烯、茴香烯、β-罗勒烯、二烯丙基二硫、6-甲基-5-庚烯-2-酮、乙酸庚酯、正辛醇、3-辛酮、正己醇、1-壬醇、松油醇及苯乙烯对新疆大盘鸡的香气起修饰作用。     

基于KV31的无刷直流电机控制系统设计

为提高港口机电设备的能源利用率,提出以无刷直流电机作为驱动机构,替代目前广泛使用的三相异步电机。控制系统作为无刷直流电机的重要组成部分,对于电机性能表现至关重要。系统以 NXP的 KV31 微控制器作为控制核心,按照模块化思想,对无刷直流电机的软硬件进行设计,其中包括核心控制电路、功率驱动电路和转子位置信号检测电路等;根据港口机械中的电机存在的实际工况,设计阶跃负载实验等多组实验进行测试。实验结果表明,所设计的无刷直流电机控制系统运行稳定可靠,能够满足性能要求。     

Windows CE下GPS与PDA串行通信的实现

论述了在Windows CE嵌入式系统中,利用串口实现GPS和PDA通信的方法;简要介绍了Windows CE串行通信基础知识以及PDA与GPS接收机的串行连接方法;详细说明在eVC4．0环境下开发串口通信程序,并给出了具体步骤和部分实现函数;阐述了对所接收到的GPS数据的处理。     

基于维特比算法的连续相位调制信号解调研究

文中对连续相位调制信号的解调算法作了相关研究。阐述了如何在信号状态网格图的基础上应用维特比算法对信号进行解调,并分析了最大似然序列检测和基于判决反馈的减少状态序列检测这两种序列检测方法,仿真结果表明,基于判决反馈的减少状态序列检测能在几乎不损失误码性能的前提下大大减少解调运算量。     

Variational Lyapunov method and stability analysis for impulsive delay differential equations

In the paper, employing the variational Lyapunov method, stability and instability properties in terms of two measures for impulsive delay differential equations with fixed moments of impulsive effects are discussed. Some stability and instability criteria are obtained. These results much generalize the known ones. Some examples are given to illustrate the advantages of them as well.     

Two level supply chain coordination with delay in payments for fixed lifetime products

In this paper, a single-vendor, single-buyer supply chain system for fixed lifetime products is considered in the settings of both decentralized and centralized models. In the decentralized model, the vendor is the decision-maker of the supply chain. In particular, we study the coordination between the vendor and the buyer that allows the buyer to delay his payment in compensation for altering his order size. This policy has been studied in the literature for the products with unlimited lifetime. In this paper, we focus on the products with fixed and limited lifetime which is common in practice. To evaluate the efficiency of the proposed delay in payments policy, a centralized decision-making problem is modeled, where there is a common decision-maker for both the vendor and the buyer. We derive analytically tractable solutions to the proposed models. Furthermore, we prove that the decentralized model can achieve the same minimal cost as the centralized model when the vendor and the buyer’s costs of capital are equal. A detailed numerical example is presented to illustrate the benefit of the proposed delay in payments policy.