建设工程施工现场质量管理的研究

质量是建设工程的最为关键之处,加强建设工程施工现场质量管理极为重要。本文从加强建设工程季节性施工质量管理;加强伸缩缝施工质量管理;加强领导,强化责任;加强软弱地基处理等方面就如何加强建设工程施工现场质量管理进行了深入的探讨,提出了自己的建议和看法,具有一定的参考价值。     

建设工程质量的监督管理

本文分析了我国工程质量监督管理存在的问题,并介绍了具体的质量监督工作主要内容,提出了相应的质量监督措施。     

基于过程的协同技术在产品质量管理中的应用

通过分析国内外协同质量管理的应用现状和发展趋势,研究企业协同质量管理的方式方法,将基于过程的协同技术应用在产品质量管理中,提出了POD-Q质量管理方式,并在产品全生命周期中应用;在此基础建立上了基于过程的协同产品质量管理模型,实现了产品质量状态信息的实时、有序管理,进而使产品质量在产品全生命周期中得到有效保证,为企业实施协同质量管理提供一个参考模型.     

基于状态空间模型的可靠性评估方法

基于设备性能退化特征的可靠性分析是可靠性技术研究重要方向之一,但当前许多研究是基于多样本进行分析,但针对单个设备的可靠性预测问题非常有限,为此本文提出基于状态空间模型的可靠性方法进行小样本预测。首先通过在线监测技术获得反映设备状态的信号,运用小波分析方法提取监测信号的小波包能量,选取趋势明显符合设备状态变化的相关频带能量作为设备退化指标。然后对这些特征指标进行滑动平均滤波处理,提高了退化特征的信噪比,将其作为状态空间模型的输入对模型参数进行估计,从而建立退化指标的状态空间预测模型,最后预测退化指标的概率分布并计算可靠度。结合滚动轴承试验数据和铣刀磨损数据验证方法的准确性和有效性,本文为小样本事件的可靠性预测提供一个有效方法。     

基于随机状态空间模型的工程结构损伤检测

对环境激励的响应信号采用数据驱动随机子空间算法得到随机状态空间模型的状态矩阵A，并作为损伤敏感特征。为克服状态矩阵A的多样性问题，构造了非奇异线性变换矩阵T，将状态矩阵转换为能控标准型，同时将状态矩阵分解成，n个子系统（m为测点数）。为克服测试误差、噪声、环境因素的影响，引入统计模式识别技术，对每一个子系统的状态向量构造Mahalanobis距离判别函数，并定义口损伤指标，对结构进行损伤识别及损伤定位。数值实验及预应力简支梁实验验证了该方法的有效性。     

油田建设工程施工质量管理对策研究

随着油气田开发建设规模的扩展,沙漠,戈壁、盐沼、高原、山地等复杂的地貌和恶劣的自然条件给油田建设的场、站、管道、道路等施工带来了更大的难度。本文主要针对当前油田地面建设工程施工存在的质量问题及其产和的原因进行分析,进而提出解决途径。     

基于状态空间模型的机床加工精度分析

伺服进给系统的机电耦合特性直接影响数控机床的加工精度，单独针对伺服系统或机械系统建立的模型不足以准确分析系统参数对机床整机加工精度的影响。因此，综合考虑机床伺服系统与机械结构之间的耦合关系，建立伺服进给系统机电耦合动力学模型具有重要意义。首先，为保证伺服进给系统建模精度，利用状态空间法建立了机床机电耦合状态空间方程。其次，建立了伺服进给系统机电耦合Simulink模型，在此基础上采用复合控制提高系统的响应速度和加工精度。随后，利用多体动力学软件建立机床进给系统的刚柔耦合动力学模型，添加摩擦、阻尼等非线性因素，并导入Simulink与伺服系统建立耦合关系。最终，建立了卧式加工中心伺服进给系统的刚柔-机电耦合仿真加工平台，通过模拟机床加工轨迹以验证机电耦合状态空间模型的可靠性。结果表明：该状态空间模型能准确描述系统内部参数和系统输入输出的耦合关系；采用复合控制结构能有效提高系统的响应速度和加工精度。研究结果为数控机床的仿真建模和提高加工精度提供理论依据，为机床机电系统的设计提供有效指导。     

建设工程的质量监督问题探析

随着社会进步和经济的发展,中国居民在解决了人类生存"衣、食"基本需求的温饱问题之后,住房已成为居民消费需求的重要方面。工程如果发生质量问题,会影响到公共利益和公众安全,所以建设工程质量已经成为人们当前所关注的事情。     

对建设工程质量安全管理的探讨

本文主要对建设工程质量安全管理的相关问题进行了探讨分析,可供大家交流。     

探讨建设工程质量监督管理模式的改革

文中分析了我国建设工程质量监督管理的现状,并且提出了在新形势的发展背景下,建设工程质量监督管理的全新模式以及整体性的发展思路和具体的操作方式。     

Continuous-time state-space unsteady aerodynamic modeling based on boundary element method

In this paper a continuous-time state-space aerodynamic model is developed based on the boundary element method. Boundary integral equations governing the unsteady potential flow around lifting bodies are presented and modified for thin wing configurations. Next, the BEM discretized problem of unsteady flow around flat wing equivalent to the original geometry is recast into the standard form of a continuous-time state-space model considering some auxiliary assumptions. The system inputs are time derivative of the instantaneous effective angle of attack and thickness/camber correction terms while the outputs are unsteady aerodynamic coefficients. To validate the model, its predictions for aerodynamic coefficients variations due to the various unsteady motions about different wing geometries are compared to the results of the direct BEM computations and verified numerical and theoretical solutions. This comparison indicates a good agreement. Since the resulting aerodynamic model is in the continuous-time domain, it is particularly useful for optimization and nonlinear analysis purposes. Moreover, its state-space representation is the appropriate form for an aerodynamic model in design or control applications.     

Product quality improvement method in manufacturing process based on kernel optimisation algorithm

Quality data in manufacture process has the features of mixed type, uneven distribution, dimension curse and data coupling. To apply the massive manufacturing quality data effectively to the quality analysis of the manufacture enterprise, the data pre-processing algorithm based on equivalence relation is employed to select the characteristic of hybrid data and preprocess data. KML-SVM (Optimised kernel-based hybrid manifold learning and support vector machines algorithm) is proposed. KML is adopted to solve the problems of manufacturing process quality data dimension curse. SVM is adopted to classify and predict low-dimensional embedded data, as well as to optimise support vector machine kernel function so that the classification accuracy can be maximised. The actual manufacturing process data of AVIC Shenyang Liming Aero-Engine Group Corporation Ltd is demonstrated to simulate and verify the proposed algorithm.     

基于知识工程复杂产品开发过程的模型研究

 为了提高复杂产品开发的效率,驾驭复杂产品开发过程各个环节相互关联的复杂性,提出一种基于知识工程的复杂产品开发过程新模型.该模型把知识工程理论融入复杂产品开发全生命周期过程中,通过知识推理技术从数据库和知识库中获取相应开发阶段的知识和数据来驱动和指导整个复杂产品开发过程,以更好地重用设计知识.研究了该模型的关键技术,包括复杂产品开发知识处理技术和基于知识的CAD/CAM/CAE/CAPP集成技术,提出了两种知识处理方法,即基于规则-对象-框架的知识处理方法和基于规则-实例的知识处理方法,并研究了相应的推理算法;以知识库、数据库、规则库和实例库为基础,通过PDM,STEP中型文件、规则、实例和知识等,实现CAD/CAM/CAE/CAPP集成.最后,通过数据库技术、编程语言VC# . NET和CATIA软件实现了隧道掘进机（TBM）主机的快速设计系统,有效地减少了隧道掘进机主机开发的复杂性和缩短开发周期,以TBM主机为应用实例进一步介绍该模型的合理性和有效性.     

A state-space dynamic model for vapor compression refrigeration system based on moving-boundary formulation

A transient response model for vapor compression refrigeration system has been developed in the paper. The system model contains four sub-models representing condenser, evaporator, compressor and electronic expansion valve (EEV). The condenser and the evaporator are developed based on the moving-boundary formulation. Through linearization, these dynamic models are transformed into state-space representation which is expressed in the form of matrix. The compressor and EEV adopt steady models because their thermal inertia is much smaller compared with the heat exchangers (i.e., condenser and the evaporator). The system model has been validated by experiment in terms of step change of EEV opening degree and heat load as well as ramp increase of inlet temperature of coolant oil of condenser. The results show that the model simulations have a good agreement with the experimental data. The simulation errors compared with the experimental data are mostly less than 10%. Since the model proposed in this study is expressed in the form of state-space matrix, they are featured by strong portability and high computation efficiency. It allows us to investigate the thermal dynamic characteristics of a refrigeration system under any complicated conditions and develop excellent control schemes.     

基于改进灰色模型的故障预测研究

随着系统发生故障所带来的财产损失、人员伤亡以及危害性越来越大,故障预测与健康管理(PHM)技术应用越来越广泛.该文重点介绍了改进灰色模型,并利用PSO算法实现了改进灰色模型的参数优化,然后以某制导雷达系统的波束控制中某电源组合为例采集电压信号数据,算法收敛性能很好,得到的结果用于改进灰色模型进行预测精度很高.     

我国高速铁路建设技术标准研究与探讨

高速铁路代表了当今世界铁路发展的方向,也是时代发展的潮流,系统研究我国高速铁路基础理论和工程建设、运营实践,对于加快建设世界一流高速铁路,实现我国铁路技术"走出去"战略目标具有十分重要的意义。在大量理论、试验研究和建设实践基础上,系统研究了我国高速铁路主要设计标准;并通过京津城际和武广高速铁路综合试验结果分析,验证了我国高速铁路主要技术标准能够满足350 km/h高速列车运营的安全性和平稳性的要求,线路品质达到世界先进水平。     

基于随机工程误差的磁悬浮列车轨道设计方法

 为在设计阶段即考虑随机工程误差对磁浮轨道曲线的影响,基于概率统计的观点,给出了考虑随机工程误差影响的磁悬浮轨道设计方法,建立了相关的分析公式,导出了设计曲线加工成败的判据.由此将工程过程与设计相结合,设计者在设计阶段即可预测轨道加工的成败,在设计磁悬浮列车轨道时综合考虑了经济性和可靠性.     

Hygrothermal deformation of orthotropic nanoplates based on the state-space concept

This paper deals with the investigation of the effect of hygrothermal conditions on the bending of nanoplates using Levy type solution model employing the state-space concept. The nanoplates are assumed to be subjected to a hygrothermal environment. The two-unknown function plate theory is used to derive the governing differential equations on the basis of Eringen's nonlocal elasticity theory. The governing equations contain the small scale effect as well as hygrothermal and mechanical effects. These equations are converted into a set of first-order linear ordinary differential equations with constant coefficients. Analytical solution of bending response for nanoplates under combinations of simply supported, clamped and free boundary conditions is obtained. Comparison of the results with those being in the open literature is made. The influences played by small scale parameter, temperature rise, the degree of moisture concentration, boundary conditions, plate aspect ratio and side-to-thickness ratio are studied.