正等轴测图尺寸自动标注功能开发

论述了以微机绘图软件ＡｕｔｏＣＡＤＲ１４．０为图形支撑软件,开发了正等轴测图尺寸的自动标注程序。     

Auto CAD中如何绘制符合国标的机械图样

在运用Auto CAD进行设计的过程中,只要合理设置,充分掌握它的各项功能,就能方便、快捷地绘制出符合我国《技术制图》和《机械制图》有关国家标准的机械图样.     

一个(2+1)维Burgers方程

通过引进新的位势函数u =u(t,x ,y) ,导出了一个 (2 +1)维Burgers方程 :ut-uxx- 2ux- 1y ux =0。并利用齐次平衡原则导出了该方程的自 -B¨acklund变换 (BT) ,借助BT获得了 (2 +1)维Burgers方程的各种精确解 ,如多重孤立波解 ,含有任意函数的积分形式的解等     

板材冲压成形CAE分析软件KMAS在汽车覆盖件模具设计中的应用

阐述了汽车覆盖件模具设计及制造的特点和技术要求,冲压成形CAE技术在车身设计及生产工艺设计分析中的重要作用.以某货车纵梁应用CAE软件KMAS进行产品设计及工艺优化为例,提出了在进行车身件产品设计及模具设计中如何在最短时间得到最优化的工艺方案的方式和实施过程.该方案对解决车身零部件生产中常见的破裂和回弹两种缺陷具有指导意义,可以有效降低模具制造乃至整车制造成本.     

基于ANSYS优化设计的蒸发器异型管板工程图的实现

基于制冷装置蒸发器异型管板无设计标准可依的现状,文中介绍开发的蒸发器异型管板辅助设计系统。在蒸发器异形管板三维优化设计模型的基础上,采用Visual Basic对ANSYS及AutoCAD软件进行二次开发,从三维造型图提取尺寸数据,实现了蒸发器异形管板二维工程图的快速生成,为企业快速响应市场奠定基础。     

Double-counting problem of the bonus–malus system

The bonus–malus system (BMS) is a widely used premium adjustment mechanism based on policyholder’s claim history. Most auto insurance BMSs assume that policyholders in the same bonus–malus (BM) level share the same a posteriori risk adjustment. This system reflects the policyholder’s claim history in a relatively simple manner. However, the typical system follows a single BM scale and is known to suffer from the double-counting problem: policyholders in the high-risk classes in terms of a priori characteristics are penalized too severely (Taylor, 1997; Pitrebois et al., 2003). Thus, Pitrebois et al. (2003) proposed a new system with multiple BM scales based on the a priori characteristics. While this multiple-scale BMS removes the double-counting problem, it loses the prime benefit of simplicity. Alternatively, we argue that the double-counting problem can be viewed as an inefficiency of the optimization process. Furthermore, we show that the double-counting problem can be resolved by fully optimizing the BMS setting, but retaining the traditional BMS format.     

The sample autocorrelation function and the detection of long-memory processes

The detection of long-range dependence in time series analysis is an important task to which this paper contributes by showing that whilst the theoretical definition of a long-memory (or long-range dependent) process is based on the autocorrelation function, it is not possible for long memory to be identified using the sum of the sample autocorrelations, as usually defined. The reason for this is that the sample sum is a predetermined constant for any stationary time series; a result that is independent of the sample size. Diagnostic or estimation procedures, such as those in the frequency domain, that embed this sum are equally open to this criticism. We develop this result in the context of long memory, extending it to the implications for the spectral density function and the variance of partial sums of a stationary stochastic process. The results are further extended to higher order sample autocorrelations and the bispectral density. The corresponding result is that the sum of the third order sample (auto) bicorrelations at lags h,k≥1$h,k\ge 1$, is also a predetermined constant, different from that in the second order case, for any stationary time series of arbitrary length.     

Numerical continuation methods for studying periodic travelling wave (wavetrain) solutions of partial differential equations

Periodic travelling waves (wavetrains) are an important solution type for many partial differential equations. In this paper I review the use of numerical continuation for studying these solutions. I discuss the calculation of the form and stability of a given periodic travelling wave, and the calculation of boundaries in a two-dimensional parameter plane for wave existence and stability. I also describe the automated implementation of these numerical continuation procedures via the software package wavetrain (http://www.ma.hw.ac.uk/wavetrain). I conclude by discussing ongoing work on numerical continuation methods for determining the absolute stability of periodic travelling waves.     

Solventless Regeneration of Ketones from Thioketones using Clay Supported Nitrate Salts and Microwave Irradiation

Thioketones are readily converted into the corresponding ketones under solvent-free conditions using clayfen or clayan in a process that is accelerated by microwave irradiation.     

痕量氡气测量仪器自动标定装置的研制

研究了空气中痕量氡的动态稳定技术和氡及其子体浓度的准确测量方法.研制了具有氡浓度自动控制、温湿度调控、气溶胶发生/采集等功能的标准氡室,并建立了主氡室标称体积达4 m3的氡测量仪器检定/校准装置和氡子体放射性气溶胶检测与实验研究平台.研究表明,本装置测氡浓度范围为370～20000 Bq/m3;检测精确度达3％;单点校...