爆破震动作用下新浇基础混凝土的安全震动速度研究

针对新浇筑混凝土的爆破震动控制,设法利用爆破地震波(Rayleigh波)作用下的新浇筑基础混凝土受力状态的理论分析和动力有限元计算,确定的新浇筑混凝土中的震动速度及动拉应变分布,并结合不同龄期下新浇筑混凝土的允许极限拉应变,从理论上确定新浇筑基础混凝土的安全震动速度及主要影响因素.理论分析结果和计算实例表明,新浇筑基础混凝土的允许震动速度值随基岩对新浇筑混凝土的基础约束程度的提高和随混凝土强度的降低而降低,我国现行采用的新浇筑大体积混凝土基础面上的质点安全震动速度值具有较大的安全储备.     

对印制电路板环境冲击评估的研究

随着印制电路板产业飞速发展,其引发的环境问题日益受到广泛的关注。然而长期以来如何有效地进行环境冲击评估是业内研究的重点和难点。而本文采用了一种智能的简化分析方法来进行全面的环境冲击评估,以提高评估的经济效益和准确度,并希望能为决策者提供一个可供参考的环境冲击评估的理念和方法。     

SMS模型在杭州湾潮流模拟中的应用

通过对实测资料(潮位、流速、潮量)的验证,确定本次数学模型的可靠性,它能为整个钱塘江河口综合规划方案的预测提供依据。     

Occupational Factors and 5-Year Weight Change Among Men in a Danish National Cohort.

This study explored whether factors related to the work environment could predict changes in body mass index (BMI) and whether the effect of psychosocial factors was dependent on baseline BMI. The sample consisted of 1,980 male employees from the Danish National Work Environment Cohort Study. Changes in BMI between 1995 and 2000 were analyzed, by multiple regression, as a function of background variables and a series of occupational variables obtained in 1995. Age, baseline BMI, job insecurity, and psychological demands predicted changes in BMI. Job insecurity and high or low psychological demands increased the likelihood of weight gain among obese employees, whereas they increased the likelihood of weight loss among employees with a low BMI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

动态矩阵控制在浆料浓度控制系统中的应用

针对PTA生产中浆料配制过程这一有纯滞后、大时间常数的非线性系统，进行系统的动态机理分析，与工作点附近的线性化，在此基础上设计DMC-PID串级加前馈控制方案。目前该系统在扬子石化化工厂PTA装置上已成功投运。     

地震平衡技术及其在地震反演中的应用

地震平衡技术是一种在地震反演中改善井震关系的新技术。它通过单井对比、空间分形建模以及平衡处理的手段 ,克服地震反演中子波空变的影响 ,使得经过地震平衡技术处理的地震剖面井震关系得到较好改善 ,从而可以用统一的子波对研究区的地震资料进行反演     

XC气田烃类渗漏的生态环境问题探讨

利用中子活化法对四川盆地XC气田的天然气进行分析，发现其中含有20多种金属元素。通过剖面和观察点的观察分析，发现XC气田烃类渗漏，尤其是天然气泄漏对生态环境造成了较大的负面影响：改变浅表生态环境，造成植物生长发育异常，农作牧减产；降低土壤pH值，增加金属元素的水溶态，从而增加植物对其的吸收消化；同时，植物还能从天然气中直接吸收消化一些金属元素。因此，天然气泄漏使农作物吸收消化过多的有毒有害金属，损害农产品品质，应当引起严重关注。     

A stochastic model for localized disturbances and its applications

A stochastic model for local disturbances, particularly for a temporal harmonic with random modulations in amplitude and/or phase, is proposed in this paper. Results for the second moment responses of a linear single-degree-of-freedom system to this type of stochastic loading demonstrate a significant change in response characteristics due to a small uncertainty. A local phenomenon may last much longer and resonance may be smeared to a broad range. Integrated with wavelet transform, the proposed approach may be used to model a random process with non-stationary frequency content. Especially, it can be effectively used for Monte Carlo simulation to generate large size of samples that have similar characteristics in time and frequency domains as a pre-selected mother sample has. The technique has a great potential for the case where uncertainty study is warranted but the available samples are limited.