Thermodynamic Assessment of DyCl3-MCl （M= Na, K, Rb, Cs） Systems

Using the CALPHAD （Calculation of Phase Diagram） technique, the DyCl3-MCl （M = Na, K, Rb, Cs） systems were optimized and calculated. The modified quasi-chemical model in the pair approximation for short-range ordering was used to describe the Gibbs energies of the liquid phase in these systems. From the measured phase diagram data and experimental thermodynamic properties, a series of thermodynamic functions were optimized base on an interactive computer-assisted analysis. The optimized parameters and the experimental data were thermodynamically self-consistent. The optimized results were discussed.     

A CLASS OF BAND-LIMITED CHIP WAVEFORMS FOR DS-CDMA SYSTEMS

In Direct Sequence Code Division Multiple Access （DS-CDMA） systems, the chip waveform affects the implementation, system bandwidth, envelope uniformity, eye pattern and Multiple user Access Interference （MAI）. In this paper, based on an elementary density function of a second order polynomial, a class of second order continuity pulses is proposed. From this class of pulses, we can find some members having faster decaying rate, bigger eye opening, more uniform envelope and stronger anti-MAI capability than the Nyquist waveform. The normalized-bandwidth-pulseshape-factor product, the decaying rate of the tail of the time waveform, the opening of the eye diagram, and the envelope uniformity of the second order continuity pulses are addressed in the paper that provide the basic information for the selection of the chip pulse for CDMA systems.     

灵活运用数据库设计理论

简介了关系模型、键、完整性规则、E-R模型、函数依赖、模式分解和关系模式的范式等数据库技术基础和规范化设计理论，从键和完整性规则的实现、数据冗余的特殊情况和字典设计等方面论述了在实际设计工作中如何灵活运用关系数据库设计理论。     

双抽机组工况图的画法分析

双抽机组热-电负荷关系非常复杂，运行人员难于分配。介绍一种较精确的工况图画法，可以为电厂运行人员提供可靠的基础。     

钢的等温加热奥氏体形成图（IHT）的计算机绘制软件

ＩＨＴ图是制定钢的热处理工艺的重要依据。本软件对所测数据进行分段抛物处理，实现珠拟合，用ＢＡＳＩＣ语言设计出具有在半对数坐标系下绘制ＩＨＴ图的软件，再与ＡＵＴＯＣＡＤ联接，在ＣＡＤ软件支持下，自动绘出精确、实用。美观的ＩＨＴ图，本文重点介绍了ＩＨＴ软件的设计原理，特点及工作环境。     

无线传感网络覆盖中概率Voronoi模型及算法研究

覆盖是无线传感网络中最重要的问题之一,随机覆盖是目前研究的主流。基于Voronoi图的随机覆盖算法是无线传感网络领域的研究热点。目前研究中采用的Voronoi图,主要采用基于距离的Voronoi边赋权值模型,存在两个主要问题,即模型粗糙和监测节点不全。以实测的分段概率传感模型为基础,从多传感协同监测的角度构造一种概率Voronoi模型,试图解决以上问题。并且用基于概率Voronoi模型的最大突破路径算法验证了模型有效性。就掌握的文献来看,该模型是首次提出,具有较好的实用推广价值。     

用例驱动技术在需求获取过程中的应用

需求获取是软件开发过程中非常重要的环节,它贯穿于整个软件生命周期。针对系统客户和开发人员由于认识问题角度和知识的差异而存在的需求获取障碍,提出了一种基于用例的需求获取方法。该方法以用户和任务为中心,设计了一个用户需求描述模板,引导用户填写需求描述信息,开发人员利用用例驱动技术对需求描述信息进行分析和验证,最终获取全面和准确的参与者和用例信息。该构建过程不仅为构造用例图和类图奠定了基础,而且也使软件工程活动更加规范。     

基于模糊模式识别的抽油井示功图判别算法研究

针对有杆抽油井示功图诊断分析问题,研究特定故障情况下示功图特征值算法。把示功图数据通过傅里叶变换由空域转换成频域形式,仅保留较低频率上的系数a0、a1、b1,并将其作为特征值。根据所得到的特征值结合模式识别算法能够实现有杆抽油井示功图快速准确的识别和分类。实际应用表明,利用基准示功图28种类型的特征值的选取,计算出每种示功图的特征矢量,并保存到特征库中。对给定示功图特征值进行模式识别,即可得出该图隶属于哪种模式。     

Experimental investigation and thermodynamic modeling of the Mg–Sn–Sr ternary system

The isothermal sections of the Mg–Sn–Sr ternary system in the Mg-rich region at 415 and 350 °C have been determined using the scanning electron microscopy (SEM) equipped with energy dispersive X-Ray spectrometry (EDS). The existence of the MgSnSr ternary compound was confirmed in these two isothermal sections. Two new compounds, named Mg₅Sn₃Sr and Mg₂₅Sn₂₄Sr_14, were found in the present work based on the SEM/EDS results. Thermodynamic optimization of the Sn–Sr binary and Mg–Sn–Sr ternary systems were carried out using the CALPHAD (CALculation of PHAse Diagrams) technique. The Modified quasi-chemical model (MQM) was used for the liquid solution which exhibits a high degree of short-range ordering behavior. The solid phases were described with the Compound energy formalism (CEF). Finally, a self-consistent thermodynamic databases for the Mg–Sn–Sr ternary system has been constructed in the present work, which can be an efficient and convenient guidance to investigate and develop the Mg-based alloys.