Research on the Component-Centered Version Model in the PDM System

A version of a product consists of the product structure tree and the versions of all its components. The model includes two sets of data： attributes and documents describing each component. The paper discusses the version change relations between a sub-node component and a up-node component in a product structure tree, analyzes the version control system for a static reference and that for a dynamic reference and proposes a product structure model in support of dynamic reference, which is easy to use and contains a complete set of information providing an essential way of data organization for the PDM system.

A version management model of PDM system and its realization

Based on the key function of version management in PDM system, this paper discusses the function and the realization of version management and the transitions of version states with a workflow. A directed aeyclic graph is used to describe a version model. Three storage modes of the directed acyelic graph version model in the database, the bumping block and the PDM working memory are presented and the conversion principle of these three modes is given. The study indicates that building a dynamic product structure configuration model based on versions is the key to resolve the problem. Thus a version model of single product object is built. Then the version management model in product structure configuration is built and the application of version management of PDM syster is presented as a case.

A p-version embedded model for simulation of concrete temperature fields with cooling pipes

Pipe cooling is an effective method of mass concrete temperature control, but its accurate and convenient numerical simulation is still a cumbersome problem. An improved embedded model, considering the water temperature variation along the pipe, was proposed for simulating the temperature field of early-age concrete structures containing cooling pipes. The improved model was verified with an engineering example. Then, the p-version self-adaption algorithm for the improved embedded model was deduced, and the initial values and boundary conditions were examined. Comparison of some numerical samples shows that the proposed model can provide satisfying precision and a higher efficiency. The analysis efficiency can be doubled at the same precision, even for a large-scale element. The p-version algorithm can fit grids of different sizes for the temperature field simulation. The convenience of the proposed algorithm lies in the possibility of locating more pipe segments in one element without the need of so regular a shape as in the explicit model.

Demand Elasticity for China's Major Imported Agriculture Textile Material Based on Restricted Version of Source Differentiated Almost Ideal Demand System Model

By comparing China's import of major imported agriculture textile material( cotton and wool),the characteristics of import are concluded. On this basis,a restricted version of source differentiated almost ideal demand system( RSDAIDS) is used to estimate the income and price elasticity of major imported agriculture textile material from the major sources based on the data from 1992 to 2015. The results are shown as follows.( 1) Although the dependency on imported cotton is lower than wool, the fluctuation of cotton import is much more drastic; China's demand for cotton is relatively price elastic with higher expenditure elasticity compared with wool; besides,the existence of complementarity is proved between imported cotton and wool.( 2) According to the import elasticity of cotton,demand for cotton imported from India shows priority over cotton from other sources; demand for cotton imported from America is the most price-sensitive one; substitution among cotton from different sources is weak.( 3) According to the import elasticity of wool,wool imported from Uruguay has bright market prospects. In addition,wool imported from Australia has irreplaceable advantage than that from New Zealand.

Improving microwave brightness temperature predictions based on Bayesian model averaging ensemble approach

The choices of the parameterizations for each component in a microwave emission model have significant effects on the quality of brightness temperature （Tb） sim- ulation. How to reduce the uncertainty in the Tb simulation is investigated by adopting a statistical post-processing procedure with the Bayesian model averaging （BMA） ensemble approach. The simulations by the community microwave emission model （CMEM） cou- pled with the community land model version 4.5 （CLM4.5） over China's Mainland are con- ducted by the 24 configurations from four vegetation opacity parameterizations （VOPs）, three soil dielectric constant parameterizations （SDCPs）, and two soil roughness param- eterizations （SRPs）. Compared with the simple arithmetical averaging （SAA） method, the BMA reconstructions have a higher spatial correlation coefficient （larger than 0.99） than the C-band satellite observations of the advanced microwave scanning radiometer on the Earth observing system （AMSR-E） at the vertical polarization. Moreover, the BMA product performs the best among the ensemble members for all vegetation classes, with a mean root-mean-square difference （RMSD） of 4 K and a temporal correlation coefficient of 0.64.

足月臀位外倒转术成功预测模型的建立与验证

目的:建立单胎足月臀位外倒转术成功的预测模型并进行内部验证。方法:回顾分析2015年1月至2021年9月在首都医科大学附属北京妇产医院行臀位外倒转术的485例单胎臀位孕妇的临床资料,按手术结局分为成功组和失败组。采用logistic回归模型进行多因素分析,筛选出外倒术成功的影响因素作为预测因子建立预测模型,应用R软件构建预测模型的列线图。绘制受试者工作特征(ROC)曲线对模型预测性能进行评估,并运用Bootstrap法进行内部验证。结果:经产、宫缩抑制剂使用、胎儿体重<2960g、羊水指数≥11.3cm、非前壁胎盘、脐绕颈<2周是外倒转术成功的独立有利因素,纳入上述6个因素作为预测因子,建立外倒转术成功的预测模型及列线图。该预测模型的ROC曲线下面积为0.74(95%CI为0.70~0.79),此时灵敏度为71.43%,特异度为67.38%。模型的内部验证结果提示其预测曲线与临床实际曲线一致性良好。结论:基于上述预测因子建立的足月臀位外倒转术成功的预测模型具有较好的预测效能,可为临床医生进行临床咨询和选择外倒转术的适宜人群提供参考。

肺部切除术后慢性咳嗽预测模型的建立与验证

背景与目的肺部切除术后慢性咳嗽是最常见的并发症之一,严重影响患者术后生活质量,目前国内尚无关于肺部切除术后慢性咳嗽预测模型。因此,本研究旨在探讨肺部切除术后慢性咳嗽相关危险因素,构建预测模型并进行验证。方法回顾性分析2021年1月至2023年6月于中国科学技术大学附属第一医院接受肺部切除术的499例患者的临床资料和术后咳嗽情况,按7:3随机分配原则分为训练集(n=348)和验证集(n=151),根据训练集患者术后是否慢性咳嗽分为咳嗽组和非咳嗽组。使用中文版莱斯特咳嗽问卷(The Mandarin-Chinese version of Leicester cough questionnare,LCQ-MC)评估术前、术后咳嗽的严重程度及其对患者生活质量的影响,采用咳嗽视觉模拟量表(visual analog scale,VAS)和自拟的数字评分法(numerical rating scale,NRS)评估术后慢性咳嗽,采用单因素和多因素Logistic回归分析独立危险因素和模型构建,受试者工作特征(receiver operator characteristic,ROC)曲线评估模型区分度,校准曲线评估模型的一致性,绘制决策曲线分析(decision curve analysis,DCA)评估模型的临床应用价值。结果多因素Logistic分析筛选出术前用力呼气第1秒呼气量与用力肺活量比(forced expiratory volume in the first second/forced vital capacity,FEV_(1)/FVC)、手术方式、行上纵隔淋巴结清扫、行隆突下淋巴结清扫、术后胸腔闭式引流时间是术后慢性咳嗽的独立危险因素,基于多因素分析结果构建列线图预测模型。ROC曲线下面积为0.954(95%CI:0.930-0.978),最大约登指数所对应的临界值为0.171,此时敏感度为94.7%,特异度为86.6%。Bootstrap法抽样1000次,校准曲线图预测的肺部切除术后慢性咳嗽与实际发生风险高度一致。DCA显示当预测模型概率的预概率为0.1-0.9之间,患者表现为正的净收益。结论肺部切除术后慢性咳嗽严重影响患者生活质量。列线图的可视化展现形式有助于准确预测肺部切除术后慢性咳嗽,为临床决策提供支持。

Estimates of net primary productivity and actual evapotranspiration over the Tibetan Plateau from the Community Land Model version 4.5 with four atmospheric forcing datasets

The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models(LSM).Particularly in high-altitude regions,choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM simulations.Therefore,this study conducted four offline LSM simulations over the Tibetan Plateau(TP)using the Community Land Model version 4.5(CLM4.5)driven by four state-of-the-art atmospheric forcing datasets.The performances of CRUNCEP(CLM4.5 model default)and three other reanalysis-based atmospheric forcing datasets(i.e.ITPCAS,GSWP3 and WFDEI)in simulating the net primary productivity(NPP)and actual evapotranspiration(ET)were evaluated based on in situ and gridded reference datasets.Compared with in situ observations,simulated results exhibited determination coefficients(R2)ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET,respectively,among which GSWP3 and ITPCAS showed superior performance.At the plateau level,CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ET.GSWP3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and ET.The simulated ET increase over the TP during 1982-2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET,suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the TP.These results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the TP.This study contributes to enhancing the accuracy of LSM in water-carbon simulations over alpine regions.

Shell-model representations of the microscopic version of the Bohr-Mottelson collective model

The structure of the irreducible collective spaces of the group Sp(12,R),which many-particle nuclear states are classified according to the chain Sp(12,R)⊃U(6)⊃SO(6)⊃SU_(pn)(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM),is considered in detail.This chain of the PNSM was recently shown to correspond to a microscopic shell-model version of the Bohr-Mottelson collective model.The construction of the relevant shell-model representations of the Sp(12,R)group along this chain is considered for three nuclei with varying collective properties and from different mass regions.It is shown that the SU_(pn)(3)basis states of the Sp(12,R)representations belonging to the SO(6)irreps with seniorityυ≥υ0,withυ0 denoting the maximal seniority SO(6)irrep contained in the Sp(12,R)bandhead,are always Pauli allowed,but organized in a different way into different SO(6)shells.This is in contrast to the case of filling the levels of the standard three-dimensional harmonic oscillator and using the plethysm operation.Although the SU_(pn)(3)multiplets withinυ<υ0 are not all Pauli forbidden,it is safe to discard them.The results obtained in the present work are important for the practical application of the microscopic version of the Bohr-Mottelson collective model.

基于图像分割与轨迹追踪的室内饰面施工进度智能评估方法

施工进度是工程项目管理的关键组成部分,传统的进度管理多依靠人工巡检,耗时费力且无法保障进度评估的时效性。为了实现施工进度的自动化、高效化监管,针对室内施工湿作业铺贴场景,提出一套智能化进度追踪与评估框架,基于改进的Mask R-CNN深度学习框架,自动提取室内墙面和地面的瓷砖铺贴进度,基于相机轨迹追踪算法,将整个施工层的大范围施工进度识别结果映射至BIM可视化模型,为施工数字孪生奠定基础。在上海市某高层建筑项目中进行实例研究,实现了施工图像的高精度分割,验证了研究框架的可行性。该框架不仅适用于室内瓷砖铺贴,也适用于抹灰、刷涂等室内装修工程。

基于模型集和差异模型的电网模型多版本管理方法

在目前的电网调度自动化系统中,电网模型的版本管理还局限在对其时间维变化的内容进行管理的方式。文中提出一种基于模型集和差异模型的电网模型多版本管理方法,将空间维和应用维模型通过模型空间和模型树的类型划分成相应的版本空间,以模型集为基线,通过叠加不同时间生效的差异模型实现对空间、时间和不同应用维度模型的多版本管理,提升了对历史模型回溯、未来模型建模、应用模型转换的灵活性,实现了实时电网监控运行与历史、未来电网研究分析在电网模型层面的协调统一,满足了电网调度控制中心内各业务应用对时间、空间和应用维电网模型开展研究分析的需求。

基于多色图理论的PDM版本管理模型的研究

多色图是离散系统仿真经常用到的一种数学工具 .文中通过对现有 PDM版本关系模型的分析 ,提出了一种基于多色图的版本管理模型 ,用以反映在整个设计过程中完整的产品设计信息 ,并将版本集看作多色图集合 ,给出了该模型具体的操作方法 .

互联电力系统分层分解时空协调建模

随着中国互联大电网的形成,电网结构和运行方式日益复杂。目前中国电网的建模方式是调度系统只对其调度管辖范围内的电网精确建模,外网部分则采用非精确建模或简单等值处理。这种传统的建模方式不能满足互联大电网的发展要求。基于IEC61970标准和E格式规范,研究建立互联电力系统分层分解时空协调建模系统。该系统融合图数模一体化的时空协调版本管理、模型合并/拆分、外网等值等多项技术,实现各调度系统的时空协调建模,能为调度系统的横向协同、纵向贯通提供技术手段,能为提高互联大电网的在线监控、动态和静态安全稳定分析水平提供信息基础和技术支撑。

动态数据库模型的研究与应用

现有的时空数据库模型不能完全满足国家基础地理信息动态数据库的要求。本文分析总结了常用的空间数据库模型的结构和功能,提出了动态“版本-差量”模型,并利用此模型对国家基础地理信息动态数据库进行了建库试验。试验表明该模型可以很好的描述和管理复杂的基础地理信息数据,方便的查询任意时刻的空间信息及其空间关系。

一种基于网状版本模型的复杂产品设计数据管理方法研究

产品设计过程中产生的大量数据是历史设计知识的重要来源。在对象划分、关系定义及数据存储模式设计的基础上,建立了"对象过程版本库+项目版本库"的数据管理架构,提出网状关系模型实现对对象版本和项目版本的综合管理,为不同历史时期的设计知识检索提供支持,并讨论了版本控制的几种关键技术。最后以航空发动机涡轮设计数据管理为例验证了该方法的有效性。实际应用证明,这种包含了设计数据演进过程的网状版本管理方式能解决当前数据管理的难题,为工程设计提供强有力的帮助,提高设计效率和质量。

选取最大可能预测错误样例的主动学习算法

通过选取并提交专家标注最有信息量的样例,主动学习算法中可以有效地减轻标注大量未标注样例的负担.采样是主动学习算法中一个影响性能的关键因素.当前主流的采样算法往往考虑选取的样例尽可能平分版本空间.但这一方法假定版本空间中的每一假设都具有相同的概率成为目标函数,而这在真实世界问题中不可能满足.分析了平分版本策略的局限性.进而提出一种旨在尽可能最大限度减小版本空间的启发式采样算法MPWPS(the most possibly wrong-predicted sampling),该算法每次采样时选取当前分类器最有可能预测错误的样例,从而淘汰版本空间中多于半数的假设.这种方法使分类器在达到相同的分类正确率时,采样次数比当前主流的针对平分版本空间的主动学习算法采样次数更少.实验表明,在大多数数据集上,当达到相同的目标正确率时,MPWPS方法能够比传统的采样算法采样次数更少.

产品配置模型的演化与再配置

在分析产品配置的动态性、说明产品再配置的客观需求以及产品配置与产品再配置不同的基础上 ,提出了配置模型和配置单元演化的版本向上传播规则以及理想配置环境的三个不同层次 ,指出最理想的配置环境是能够描述配置模型的差异 ,并在不同时间对已配置产品进行再配置

行为安全“2-4”模型的扩充版

现有的行为安全"2-4"模型已能够精确定位事故"管理漏洞"原因的具体位置和内容,但由于未考虑事故发生内、外部组织因素的影响,因此尚不能全面揭示事故发生的原因。以行为安全"2-4"模型为基础,提出了包含几类影响因素在内的扩充版行为安全"2-4"模型,并应用该模型对国家标准给出的事故原因进行了重新归类,将事故责任者进行了科学定义与分类,同时基于该模型得到了事故预防线路图。研究得到的扩充版行为安全"2-4"模型增加了"内部影响链"和"外部影响链",这两条链中的动作发出者会通过确定的路线来影响事故的发生;应用该模型将国家标准给出的12种事故原因归为直接、间接、根本、内部影响以及外部影响原因;按照事故的责任与原因相对应原则,将事故责任者分为直接、间接、主要、内部影响以及外部影响责任者5类;将该模型中的事故、损失等不安全方面分别改为安全业绩、收益等安全方面后得到了事故预防图,可为事故预防提供借鉴。

产品结构化信息树版本管理方法的研究与实现

针对当前产品结构树生成和更新中存在的数据重复录入问题,给出了产品结构化信息树的定义,能够表达产品任意零部件的产品结构及其关联文档数据,采取文档版本变化驱动产品结构树的版本变化的方法,建立了产品结构化信息树版本模型,提出了一套基于控制锁的版本控制规则,能够对产品结构化信息树的版本变化进行控制,避免了版本冗余。基于版本控制规则,论述了任意零部件文档签出或修订前后产品结构化信息树版本变化的求解方法。按照版本的不同,将项目所属文档按照产品结构树的版本分文件夹地保存在物理硬盘上,便于物理文档的维护和备份。最后通过企业的实际系统应用实例,对所提出的版本控制规则和方法进行了验证。

两种温室气体排放情景下中国汛期江淮暴雨低涡特征研究

本文基于一个水平分辨率为50 km的区域气候模式Reg CM4(Regional Climate Model,version 4.0)的模拟与预估结果,对我国汛期江淮暴雨低涡在气候变化背景下的统计特征与合成结构进行分析,进一步对两种温室排放情景下未来中国汛期的江淮暴雨低涡特征进行预估。结果表明:Reg CM4模式对环境要素及低涡都具有一定的模拟能力,低涡的伸展高度、生命期及暴雨位置模拟结果与观测较为接近,但模拟的低涡个数、最大暖区高度以及温、湿要素分布均比实际略偏低,而风速和低涡的强度模拟则偏强;在未来两种温室排放情景预估方面,RCP4.5(Representative Concentration Pathways,简称RCP)典型浓度排放情景下,暴雨低涡数量比例减少,强度减弱,但低涡发展高度仍以850 h Pa为主,生命期多为2 d以内,低涡雨区分布及最大暖区高度均与历史时段相近;RCP8.5情景下,暴雨低涡比例明显大于RCP4.5情景,低涡发展高度以700 h Pa为主,生命期达3 d的增多,强度增强,最大暖区厚度范围显著伸展。两种情景下均有低涡中温度锋区减弱,而湿度锋区增强,但RCP8.5情景减弱与增强更显著,显示更高的温室气体排放将导致未来出现更强的暴雨低涡,造成伴随暴雨的低涡灾害性天气的增加,因此应进一步深化对低涡暴雨灾害性天气发展趋势的研究。