心源性猝死一级预防植入心律转复除颤器前非持续室性心动过速与植入后恰当治疗的关系

目的探讨植入型心律转复除颤器(implantable cardioverter defibrillator,ICD)用于心源性猝死一级预防时,植入前发生非持续性室性心动过速(non-sustained ventricular tachycardia,NSVT)与植入后ICD恰当治疗的关系。方法本研究为单中心回顾性队列研究,连续纳入2006年1月至2017年12月在北京协和医院住院植入ICD用于一级预防的心脏病患者,患者在住院期间ICD植入前均完善Holter检查。根据Holter检查是否出现NSVT,将患者分为NSVT组及无NSVT组。门诊或电话随访至2018年8月,随访事件包括全因死亡、植入后ICD放电治疗及抗心动过速起搏(antitachycardia pacing,ATP)治疗情况。结果纳入60例符合入选和排除标准的患者,随访时间37 (14～61)个月,KaplanMeier生存曲线及Log-Rank检验提示,NSVT组与无NSVT组相比,全因死亡率无统计学差异(P=0. 108),NSVT组恰当治疗的风险高于无NSVT组(P=0. 033),NSVT和左心室射血分数与ICD恰当治疗独立相关(NSVT:HR=5. 099,95%CI:1. 399～18. 588,P=0. 014;左心室射血分数:HR=1. 077,95%CI:1. 013～1. 145,P=0. 018)。结论 ICD一级预防患者植入前出现NSVT提示接受ICD恰当治疗的风险增加。     

高性能调度技术中应用程序调度模型设计--地理空间信息网格调度技术的研究

地理空间信息网格调度技术，要比传统的高性能计算中的调度技术复杂，原因是如果将全部网格资源作为一个应用程序的调度和执行目标，必将导致通信延迟、成本昂贵、执行低效等。为此，综合考虑应用程序特性、机器特性等，研究设计了地理空间信息网格高性能调度技术中的应用程序调度模型，包括地理空间信息网格应用程序分析；资源特性分析；应用程序分解；性能预测；资源调度；机器选择；任务映射；任务调度；任务调度器和调度器管理模块。以实现为不同的应用程序匹配不同的计算资源，提高计算资源的利用率和应用程序的执行效率。     

船闸直立墙基坑开挖与锚固施工程序

三峡船闸深槽开挖与锚固工程量大，工期紧，施工强度高，施工难度大。因此，合理的施工程序有利于边坡稳定和施工，是快速和高质量施工的关键。分析了永久船闸直立墙基坑开挖与锚固施工程序的复杂性和进行研究的必要性。介绍了设计阶段研究船闸开挖与锚固的施工程序。对施工过程中研究施工程序时考虑的因素，研究的主要内容以及实际采用的施工程序作了简要的分析，归纳和总结。     

Influence of accelerated ageing on methacrylate‐based denture resins heterogeneity as viewed by ESR‐spin‐probe method

The electron‐spin‐resonance (ESR) spin‐probe method, was used to study the heterogeneity of denture resins based on poly(methyl methacrylate). Results for three resins processed by microwave energy, conventional curing and cold curing (depending on the curing procedure and exposed to ageing in various environmental conditions) were compared. All three cured resins were stored over the same time (1200 h) in distilled water at ambient temperature and in artificial saliva at 348 K. The temperature‐dependent ESR spectra of a spin probe dispersed in the denture resins are analyzed in terms of line‐shapes and line‐widths. The appearance of two spectral components was taken as an indication of resin heterogeneity. The results reveal that the cold‐cured resin has a lower local density in comparison with microwave and conventionally cured resin. The amount of residual monomer also contributes to the local motion of polymer segments. The change of denture resins exposed to ageing is influenced both by the structure of the original resin and the ageing conditions. Restricted motion of a spin probe incorporated into the acrylic resins exposed to accelerated ageing suggests additional crosslinking of polymer chains. The differences are observed for all the investigated resins, but the highest change is observed with the cold‐cured resin. The ESR results are accompanied by T_g and T_m measurements. Copyright © 2005 Society of Chemical Industry     

Solution of a multidimensional inverse radiation problem by means of mode reduction

The Karhunen–Loève Galerkin procedure is employed to solve an inverse radiation problem of determining the time‐varying strength of a heat source, which mimics flames in a furnace, from temperature measurements in three‐dimensional participating media where radiation and conduction occur simultaneously. The inverse radiation problem is solved through the minimization of a performance function, which is expressed by the sum of square residuals between calculated and observed temperature, using a conjugate gradient method. Through the Karhunen–Loève Galerkin procedure, one can represent the system dynamics with a minimum degree of freedom, and consequently the amount of computation required in the solution of the inverse problem is reduced drastically when the present technique is adopted. Copyright © 2004 John Wiley & Sons, Ltd.     

A direct estimate of JIc from the load versus load-line displacement record

The purpose of this study is to examine the current standard fracture toughness test procedure to determine if there could be an easier method to get a J_Ic value from the test record. The current method for determining J_Ic involves a detailed computational and construction procedure. The objective in this study is to simplify the analysis for the determination of J_Ic. The results of this study show that the load and displacement record for a fracture toughness test can be used to directly estimate a J_Q value, a provisional value for fracture toughness, J_Ic. The J value taken at the maximum load point can be used along with an adjustment factor to estimate a J_Q value. This J_Q estimate is close to the one obtained from the construction procedure of ASTM Standard E 1820. When a unit‐sized specimen is tested, that is, a specimen with a width of 50 mm and a thickness of 25 mm the maximum load point provides a direct estimate of J_Q. Other sizes require a size adjustment factor, which is simply a square root relationship between the width of the test specimen and a unit width. The proposed new method of estimating J_Q is simple in concept and requires a minimum number of calculations. It appears to produce values of J_Q which are comparable to those obtained from the ASTM E1820 construction procedure and may produce less scatter.     

Bayes estimators for reliability measures in geometric distribution model using masked system life test data

This paper presents Bayes estimators for the reliability measures of the individual components in a multi-component systems in the presence of masked system life test data. The life time distributions of the system components are assumed to be geometric with different parameters. Two-sided Bayesian probability intervals of the parameters are also derived. Numerical simulation study is given in order to: (i) explain how one can apply the theoretical results obtained, (ii) study the influence of the sample size and masking level on the accuracy of point estimates.     

炼钢厂成本分析信息系统的开发设计

文章介绍了包钢炼钢厂生产管理信息系统中成本分析子系统的可行性分析以及具体的数据归集流程,详细介绍了该系统的开发环境以及该系统的模块和数据库的结构、功能及其具体的设计思想;简要介绍了Oraele Develop数据库开发应用的一些特点.     

安钢集团信息化实施策略探讨

近年来，为了更好地应对新的市场挑战，钢铁企业都在积极推进信息化建设，以实现管理提升、效益提升的目标。本文结合安钢集团的实际情况，对信息化实施策略进行初步的探讨，希望能对企业信息化建设有所借鉴。