A Fast Method of Transforming Relaxation Functions Into the Frequency Domain

The limits to the error due to truncation of the numeric integration of the one-sided Laplace transform of a relaxation function in the time domain into its equivalent frequency domain are established. Separate results are given for large and small ω. These results show that, for a given ω, only a restricted range of time samples is needed to perform the computation to a given accuracy. These results are then combined with a known error estimate for integration by cubic splines to give a good estimate for the number of points needed to perform the computation to a given accuracy. For a given data window between t₁ and t₂, the computation time is shown to be proportional to ln(t₁/t₂).     

清单计价势在必行

为推行政府宏观调控、企业自主报价的管理，就实行清单计价的必然性作了阐述，从强制性、实用性、竞争性等方面，提出了计价规范特点的主要表现。     

关于工程签证的结算审核

根据工作中的实际经验,就工程结算签证的处理和操作中一些普遍存在的具体问题的原因进行了分析,探讨了解决的途径和防范措施,从而把工程签证的结算工作做好。     

关于水电建设项目上网电价测算若干问题的浅析

国家有关部门规定的上网电价确定原则主要包括峰谷分时电价原则、丰枯电价原则和新电新价原则。水电建设项目上网电价的测算主要有以下几种方法：还贷期间按归还贷款本息反推，还清贷款后按满足本行业基准收益率测算；根据电网电价的上涨趋势及用户的承受能力测算；采用边际成本法测算；采用合理的资金利润率测算。在测算建设期较长的水电项目上网电价时，要考虑通货膨胀因素对上网电价的影响、建设期应计利息的划分、资本金应付利润     

On application of two superconvergent recovery procedures to plate problems

In this paper a study is performed on application of two recovery methods, i.e. superconvergent patch recovery (SPR) and the recovery by equilibrium of patches (REP), to plate problems. The two recovery methods have been recognized to give similar results in adaptive solutions of two dimensional stress problems. While the former applies a least square fit over a set of values at the so called superconvergent points, the latter does not need any knowledge of such points and thus has a wider application especially in non‐linear problems. The formulation of REP is extended to Reissner–Mindlin plate problems. The convergence rates of the recovered fields of the gradients obtained from application of the two methods are compared using series of regular triangular and rectangular meshes for thick and thin plate solution cases. Assumed strain formulation based elements, i.e. the elements formulated by mixed interpolation of tensorial components, as well as conventional from of elements based on selective integration schemes are employed for the study. In order to investigate the possibility of any improvement in the results by adding equilibrium constraints to SPR, as some authors suggest for simple two‐dimensional problems, some weighted forms of such conditions are designed and added to the formulation. Comprehensive study has been given first by varying the weight terms to obtain the best enhanced results and then using the optimal values to investigate the effects of the constraints on the rate of convergence. It is observed that despite of the cost of this approach, due to the coupling of the gradient terms, no significant improvement is achieved. Copyright © 2004 John Wiley & Sons, Ltd.     

UNIVERSAL FORMULAE OF ROBUST ESTIMATES OF PARAMETER VECTOR AND VARIANCE COMPONENTS

ＵＮＩＶＥＲＳＡＬＦＯＲＭＵＬＡＥＯＦＲＯＢＵＳＴＥＳＴＩＭＡＴＥＳＯＦＰＡＲＡＭＥＴＥＲＶＥＣＴＯＲＡＮＤＶＡＲＩＡＮＣＥＣＯＭＰＯＮＥＮＴＳ①ＷａｎｇＺｈｉｚｈｏｎｇＩｎｓｔｉｔｕｔｅｏｆＳｕｒｖｅｙｉｎｇＥｎｇｉｎｅｒｉｎｇａｎｄＬａｎｄＩｎｆ...     

半导体问题的特征有限元方法和H1模估计

研究三维热传导型半导体瞬态问题的特征有限元方法及其理论分析，其数学模型是一类非线性偏微分方程的初边值问题。对电子位势方程提出Galerkin逼近；对电子、空穴浓度方程采用特征有限元逼近；对热传导方程采用对时间向后差分的Galerkin逼近。应用微分方程先验估计理论和技巧得到了最优阶H^1误差估计。     

一种基于非参数统计的微波集成电路成品率优化算法

给出了一种新的微波集成电路成品率优化算法——基于非参数统计的成品率快速优化算法。利用该方法，仅需要较少的仿真次数或直接利用非参数统计成品率分析算法的结果，便可直接得出一组或几组参数的成品率优化值，有效地缩短了优化时间。算例表明，该方法对微波集成电路进行快速成品率优化设计及提高电路设计的稳定性具有较好的应用价值。     

利用GETTIM函数求全局极小值

利用FORTRAN语言提供的GETTIM函数，在规定的范围内，产生一组组随机值，作为优化的初始值，求全局极小值，明显地提高了优化结果的可靠度。     

牛顿优化法在地下水位曲线拟合中的应用

 在非线性拟合中，常采用变量替换的方法使之线性化，再按线性模型处理。但这种方法并非无偏估计。 采用牛顿法逐次改进其参数，使之逼近无偏，从而提高曲线拟合精度。实例计算表明 此法用于地下水位的曲线拟合效果显著。