基于无源雷达模拟器的幅度算法研究

以无源雷达模拟器为基础,讨论了在不同工作模式下,目标信号幅度的计算方法,并对两种工作模式下信号幅度的取值进行了仿真。针对微波器件频率特性引起的差异,介绍了一种信号幅度调整的方法,对于“真实”的模拟目标信号,具有一定的实践和指导意义。     

Experimental simulation on dynamic variation of the permeability of high-rank coal reservoirs

In terms of the coal reservoir permeability of effective stress, coal matrix shrinkage and gas slippage, we conduct the tests of gas permeability under constant confining pressure and effective stress, as well as illustrate the cumulating method of permeability increment caused by the effects of gas slippage and coal matrix shrinkage. The results show that under the constant confining pressure, gas slippage affecting coal permeability changes to effective stress affecting it mainly. The change point increases with the increase of the confining pressure. The gas slippage effect leads to high permeability under low confining pressure, but coal matrix expansion results in the low value as confining and gas pressures increase. Combined with the drainage process of coalbed methane (CBM) well, the permeability is divided into four change stages based on the above analysis about the three effects, which can improve the change regulation understanding. Four stages are the downward phase under effective stress, the conversion phase of effective stress-coal matrix contraction effect (mainly based on effective stress), the rising stage of the effective stress-coal matrix contraction effect (mainly based on coal matrix contraction effect) and the rising phase of coal matrix contraction-slippage effect (mainly based on slippage effect). Permeability of coal reservoir during the process of drainage and production goes through four stages.     

不明原因不孕妇女月经周期中血清微量元素的研究

对19例不明原因不孕和14例已育健康妇女共33个月经周期中血清锌、铜、铁、锰、镍含量进行分析。结果表明：对照组排卵日血清锌、铜明显低于印泡中期和黄体中期，印泡中期铁、镍含量最高，在周期中呈递减趋势（P均＜0．05）；与对照组比较，不孕组除印泡中期镍减低外，各期血清钢及黄体中期锌、镍、铁均显著增高（P＜0．001，P＜0．05，P＜0．01），而各期血清锌／铜、铁／铜比率明显降低（P＜0．05）。研究提示：正常妇女月经周期中微量元素水平具有规律的周期变化，且相互存在恒定的比值，微量元素的代谢紊乱可能是不明原因不孕的重要因素之一。     

Optimal subwork zone operational strategy for short‐term work zone projects in four‐lane two‐way freeways

Roadside trees in Singapore are regularly trimmed for the purpose of traffic safety and roadside tree‐trimming project is one typical type of short‐term work zone projects. To implement such a short‐term work zone project, contractors usually divide an entire work zone into multiple subwork zones with the uniform length. This paper aims to determine an optimal subwork zone strategy for the short‐term work zone projects in four‐lane two‐way freeways with time window and uniform subwork zone length constraints. The deterministic queuing model is employed to estimate total user delay caused by the work zone project by taking into account variable traffic speeds. Based on the user delay estimations, this paper proceeds to build a minimization model subject to time window and uniform length constraints for the optimal subwork zone strategy problem. This paper also presents a variation of the minimization model to examine the impact of unequal subwork zone length constraint. Since these minimization models belong to the mixed‐integer non‐differentiable optimization problems, an iterative algorithm embedding with the genetic simulated annealing method is thus proposed to solve these models. Finally, a numerical example is carried out to investigate the effectiveness of the proposed models. Copyright © 2010 John Wiley & Sons, Ltd.     

水上飞机与船舶碰撞风险因素建模

我国民用水上飞机产业正处于起步阶段,保障水上飞机的航行安全是十分重要的.结合水上飞机水面滑行及起降过程的动态特点,运用人机工程理论,识别了水上飞机与船舶的碰撞风险因素,确定了各因素之间的相互关系及其影响程度;通过集成决策实验室分析法和解释结构模型法(DEMATEL-ISM)计算得出各碰撞风险因素的中心度和原因度,确定了各因素的重要程度,明确了各因素中原因因素和结果因素的归属;构建了四层次的水上飞机与船舶碰撞风险因素多级递阶结构模型.此研究为该类事故的分析、预防及水上交通安全管理提供了方法和依据.     

基于神经网络模型的软基工后变形分析

基于神经网络理论和反向传播算法，建立了软基工后变形预测夯析人工神经网络模型。并借助Matlab语言进行程序设计，实现神经网络计算。结合汕汾高速公路软基工后沉降实测数据，对模型进行学习训练，并利用神经网络模型进行工后变形预测。验证表明，预测值与实测值有较好的一致性，同时也说明作为非线性科学一个分支的神经网络，由于其能以较高的精度去逼近任意非线性函数。在软基变形分析上显示出较强的实用价值和优越性。     

港口机械设备的维修涂装

论述港口机械设备腐蚀的原因,防腐涂层保养应注意的事项,维修涂装时期的确定方法,钢材表面除锈去污处理方法及其质量要求,维修涂装涂料配套性的选择原则和方法,维修涂装施工步骤及其要领,以及涂层质量验收要求.     

沥青路面养护技术现状及发展

随着公路建设事业的发展,我们面临着越来越严峻的公路养护和改建问题。本文简单介绍了目前我国沥青路面养护技术现状及存在问题,重点介绍了微波加热法沥青路面修复技术,指出了沥青路面养护技术的发展趋势。     

Real time traffic information and its impacts on route switching behavior of expressway drivers

Non‐quantifiable factors (e.g. perceived, attitudinal and preferential factors) have not been investigated fully in past transportation studies, which has raised questions on the predictive capabilities of the models. In this study, Structure Integration Models, with one of their sub‐models, Measurement Equation, are combined with latent variables, which are integrated with another sub‐model, Structural Equation. The estimated latent variables are used as explanatory variables in decision models. As a result, the explanatory and predictive capabilities of the models are enhanced. The models can then be used to describe the various behaviors of travelers of different types of transportation systems in a more accurate way. In this study, the Structure Integration Model was applied to study the impacts of real‐time traffic information on the route‐switching behavior of road users on the Sun Yat‐Sen expressway, Taiwan. At present, the real‐time traffic information provided on this expressway includes radio traffic reports and changeable message signs. The results of this study can facilitate the provision of traffic information on highways.