房地产开发投资控制的几点思考

项目开发的决策阶段和设计阶段,是决定整个项目投资的关键阶段,开发方案一经确定项目的投资也就基本上确定了。本文分别从决策阶段、设计阶段、招投标阶段和施工阶段对房地产开发中如何进行投资控制做了详细阐述,供大家参考。     

低密频太阳能帆板动力学参数在轨辨识和振动控制

太阳能帆板是典型的柔性空间结构,其固有频率低且密集,阻尼很小。为了抑制其振动,建立了基于动力学参数辨识的振动控制方法。该方法利用特征系统实现算法及其扩展算法如ERA/DC或OKID辨识结构的动力学参数,然后利用最优控制理论设计控制器。根据辨识和控制的方法以及适用的情况,提出了三种在轨辨识和控制集成方案,即ERA(ERA/DC)和LQR或LQG,OKID和LQG。对一具有低密频大型柔性空间站结构的数值仿真表明,上述在轨辨识和控制集成方案具有辨识速度快,辨识精度高,控制效果好等优点,适于柔性空间结构的在轨辨识和控制。     

建筑工程项目管理相关问题分析

建设工程项目管理是以建设工程项目为对象的系统管理方法,通过一个临时性的专门性的柔性组织,对项目进行高效率的计划、组织、指导和控制,以实现项目全过程的动态管理和项目目标的综合协调与优化。本文从进度控制、质量控制和成本控制等几方面对工程项目管理进行论述。     

成本控制理念下的轻便两用摩托车创新设计

目的探索在产品创新设计阶段如何依托成本控制理念,实施产品创新设计,并权衡设计、功能、成本之间的关系。方法以望江轻便两用摩托车设计实践项目为例,从预防性成本控制与前馈性成本控制两个角度出发,探讨如何展开设计准备工作,并从产品造型、结构、材料、装饰等4个方面,对初步方案进行设计、成本分析和方案改进,最终形成基于成本预算与方案满意度评价的方案决策。结论以案例实证方式,验证在产品创新设计阶段,将成本控制理念与方法融入创新设计中,对设计方案进行辅助性方案评价、修改与决策,能够有效权衡创新设计、功能、成本等因素,更准确地把握设计方向并提升产品创新设计可实施性,为产品创新设计阶段的成本控制与设计创新提供新思路。     

参数不确定漂浮基柔性空间机械臂载体姿态、关节协调运动及柔性振动主动抑制的混合控制方案

讨论了载体位置不受控、姿态受控情况下,漂浮基柔性空间机械臂系统可保证载体姿态、关节角协调运动变结构控制鲁棒性并同时抑制所产生柔性振动的混合控制方案。该变结构控制仅设计来完成渐近解耦的载体姿态及关节角轨迹追踪,而不能对柔性振动模态进行控制;为了主动抑制柔性杆的振动,使用虚拟控制力的观念生成了变结构控制所需的混合轨迹,从而为柔性空间机械臂设计了追踪混合轨迹的混合控制方案。数值仿真结果证实了该混合控制方案在系统参数不确定情况下,能够使载体姿态及机械臂关节角稳定地追踪期望轨迹并对所产生的柔性振动进行主动抑制。     

柔性空间机械臂基于混合滑模思想的自适应变结构控制

研究了柔性空间机械臂协调运动控制及柔性振动抑制问题。利用假设模态法及系统动量守恒关系,导出了空间机械臂的系统动力学模型。基于混合滑模思想,针对系统惯性参数存在不确定的复杂情况,提出了一种柔性空间机械臂本体姿态、关节协调运动的自适应变结构控制方案。该文所引入的混合滑模由频率成形最优滑模及终端滑模两部分组成。前者用于抑制系统柔性杆件的振动,后者则是为了保证系统追踪误差在有限时间内的收敛性。此外,上述控制方案由于在控制过程中无需预知系统的柔性变量,因此可有效避免对系统柔性状态变量进行实时地测量与反馈,较适于实际应用。仿真运算,证实了所提控制方法的有效性。     

浅谈柔性直流输电系统的启动控制

2011年5月3日,亚洲首条柔性直流输电示范工程——上海南汇风电场柔性直流输电工程成功投入试运行,这是我国首条拥有完全自主知识产权、具有世界一流水平的柔性直流输电线路,也是我国在大功率电力电子领域取得的又一重大创新成果,标志着国家电网公司成为继ABB、西门子之后全球第三家掌握柔性直流输电技术的公司,将为我国风电场大规模、集中式开发提供重要技术支撑。本文主要阐述了柔性直流输电系统的启动控制。先简述了柔性直流输电的基本原理,并对柔性直流输电换流站级的控制予以简明论述,从而提出柔性直流输电系统的启动控制。对启动控制的分析主要是从柔性直流输电系统启动控制的必要性、柔性直流输电系统启动控制的实现方法、换流站启动限流电阻配置方案及复合启动控制策略等四个方面进行的。     

漂浮基柔性空间机械臂关节运动的拟增广自适应控制及柔性振动实时主动抑制

讨论了载体位置、姿态均不受控情况下,自由漂浮柔性空间机械臂系统关节运动的拟增广自适应控制和柔性振动实时主动抑制问题。此类机器人系统的特点在于:结合系统动量及动量矩守恒关系得到的完全能控形式的系统动力学方程,关于系统惯性参数不符合惯常的线性函数关系,因此地面机器人的控制方法在此难以直接推广应用。为了克服上述难点,我们仅将系统动量守恒关系耦合到系统动力学方程当中,而不耦合系统动量矩守恒关系,结果得到一组欠驱动形式的系统动力学方程。其优点在于,系统动力学方程关于一组组合惯性参数保持惯常的线性函数关系。以此为基础,设计了具有未知参数柔性空间机械臂关节轨迹跟踪的拟增广自适应控制方案。并根据柔性子系统的动力学特性,设计了一个基于反馈的自适应控制方案来对柔性杆的振动进行快速实时的抑制。所提出的控制方案还具有不需要测量、反馈载体位置、移动速度和移动加速度的显著优点。系统的数值仿真,证实了方法的有效性。     

井下深孔爆破模型模拟试验研究

介绍了井下深孔爆破模型模拟试验的方法。对大冶铁矿三个典型的深孔爆破方案进行了设计和模型试验。通过对试验结果定量分析 ,验证了侧向抛掷爆破出矿方案优于单排齐发爆破 ,为现场爆破方法的决策提供了依据     

关节柔性的漂浮基空间机器人基于奇异摄动法的轨迹跟踪非奇异模糊Terminal滑模控制及柔性振动抑制

如果在漂浮基空间机器人系统动力学建模和控制方法设计过程中忽略关节柔性的存在,其控制系统的精度和稳定性将受到极大影响。以考虑关节柔性、系统参数不确定的漂浮基空间机器人系统为研究对象,讨论了其动力学建模过程、运动轨迹跟踪控制方案设计及柔性振动振动抑制。结合拉格朗日第二类方法并结合系统动量、动量矩守恒关系,分析、建立了系统动力学方程。以此为基础,为了同时实现空间机器人运动轨迹的渐近跟踪和抑制由关节柔性引起的系统弹性振动,采用奇异摄动理论的双时间刻度分解,将系统分解为表示系统刚性运动部分的慢时标子系统和表示系统柔性运动部分的快时标子系统。针对慢时标子系统设计了非奇异模糊Terminal滑模控制方案。该控制方案采用非奇异Terminal滑模面,并基于模糊逻辑系统自适应调整控制律的切换项,不但克服了在设计中需要知道系统不确定性的上界的限制,又消除了滑模变结构控制器抖振的缺点。针对快时标子系统,采用速度差值反馈控制律来抑制关节柔性引起的系统弹性振动,保证系统的稳定性。仿真时以平面两刚性臂、两柔性关节的漂浮基空间机器人系统为例证明了所提出方法的有效性。     

考虑公有与私有资源约束的多项目调度规则对比研究

为了识别出适用于具有公有资源与私有资源约束的多项目调度问题的优先规则,基于标准测试集MPSPLIB进行计算实验,并基于相对偏差指标对比分析25种经典优先规则在最小化最大完工时间、最小化总拖期、最小化加权总拖期3种决策目标下的表现。实验结果表明,优先规则的表现与决策目标、单项目任务数、并行项目数、资源利用系数等因素之间具有显著相关性。在最小化总拖期目标下,尽管大多数规则的表现与现有文献总体一致,但是MAXTWK和MINSLK规则的表现有着显著差异。所得实验结论对于工程实际多项目调度决策具有指导意义。     

Analysis of a multi-criteria project crashing model

The purpose of this paper is to report on the model formulation and results of a multi-criteria time-cost (crashing) CPM project network. In the project of interest (the installation of a bank paper processing system), multiple and conflicting objectives concerning both time and cost must be incorporated into the decision analysis. The project network is, therefore, formulated as a goal programming model, including the various managerial objectives as goal constraints and associated priorities.     

Transparency in environment impact assessment decision-making: recent developments in Western Australia

Transparency in decision-making, involving the establishment of explicit goals and objectives combined with open, facilitative procedures, has recently been advocated as an important principle for effective environmental impact assessment (EIA). This paper examines recent changes to EIA practice in Western Australia that emphasise clear procedures for decision-making. Current practices focus on objectives established for relevant environmental factors identified during the screening and scoping stages of EIA. These objectives are then used as decision criteria for project decision-making following public review. An example from a recent assessment is provided. Some strengths and weaknesses of this approach to transparent EIA decision-making are also examined.     

Emergy-based life cycle assessment (Em-LCA) for sustainability appraisal of infrastructure systems: a case study on paved roads

Civil infrastructure systems are critical assets that are subjected to damage, service-life deterioration, and increasing maintenance and rehabilitation cost. Effective infrastructure management and principles of sustainable development can help to find an optimal compromise between economic growth and environmental protection for all stakeholders. Colloquially, sustainability refers to meeting triple-bottom-line (TBL) performance objectives including environmental protection, economic prosperity, and social acceptability and equity as a result of short- and long-term policy decisions. In this paper, a comprehensive framework based on the integration of emergy synthesis and life cycle assessment (LCA) has been investigated for a public infrastructure system. The main purpose of the applied method, emergy-based LCA (Em-LCA), is to facilitate an informed decision making process for different asset management scenarios, by identifying and quantifying the attributes of TBL impacts over the life cycle of a civil infrastructure system. As a case study, Em-LCA framework has been applied to evaluate the sustainability of two different scenarios for a road construction project in interior British Columbia, Canada. The results indicate that Em-LCA offers a good understanding to address sustainability issues in infrastructure systems and provides quantitative and transparent results to facilitate informed decision making for asset management.     

Establishing sensitivity requirements for environmental analyses from project data quality objectives.

This article proposes a simple strategy for establishing sensitivity requirements (quantitation limits) for environmental chemical analyses when the primary data quality objective is to determine if a contaminant of concern is greater or less than an action level (e.g., an environmental "cleanup goal," regulatory limit, or risk-based decision limit). The approach assumes that the contaminant concentrations are normally distributed with constant variance (i.e., the variance is not significantly dependent upon concentration near the action level). When the total or "field" portion of the measurement uncertainty can be estimated, the relative uncertainty at the laboratory's quantitation limit can be used to determine requirements for analytical sensitivity. If only the laboratory component of the total uncertainty is known, the approach can be used to identify analytical methods or laboratories that will not satisfy objectives for sensitivity (e.g., when selecting methodology during project planning).     

A critical evaluation of the strategy project

The STRATEGY project (sustainable restoration and long-term management of contaminated rural, urban and industrial ecosystems; www.strategy-ec.org.uk) addressed the need for a holistic decision framework for the selection of optimal remediation strategies for long-term sustainable management of contaminated areas in Western Europe. The project considered both technical and social aspects of implementing restoration strategies for urban and rural environments. The importance of considering socially relevant objectives in addition to the dose reduction was emphasised. A critical evaluation was carried out on 101 selected countermeasures, (including rural waste disposal options), a model was developed to aid optimising countermeasure strategies and a method of carrying out participatory decision-making suggested. The outputs of the project are described and critically evaluated.     

基于项目质量控制人的因素研究

人的因素是项目质量控制中的第一因素。项目经理不仅要具备计划、组织、控制及技术等技能，还应具备良好的沟通技巧、处理压力和协调能力，同时要分清项目经理和职能经理的职责，赋予项目经理与责任相应的权力。由于项目组织是一个团队，做好团队内的有效沟通、项目的协调是工作的必要条件，同时需要适当的授权，使每一个相关责任人都主动、自觉地去工作，以期达到项目质量控制的目标。     

基于委托代理理论的建设项目多要素协同激励控制模型研究

激励控制是确保项目工期、质量和成本目标实现的基础,传统的建筑项目激励模型多考虑的是一个或某两个目标的激励控制。有关多要素激励模型的研究尚不成熟。没有考虑到多要素之间的关联性,以及质量目标难以量化等。这容易导致建筑项目在施工过程中忽视一些重要因素,造成无法挽回的损失。针对上述问题,本文引入挣值管理(earned value method, EVM)中两个基本业绩测度,同时将质量因素量化,考虑多要素间的可替代性,建立了一个多要素委托代理模型,并对模型的应用条件进行了说明。进一步给出了最优激励强度的计算方法以及模型的应用步骤。最后,进行了案例研究和数据模拟。     

基于Max-npv的项目进度与支付集成优化

以某房地产项目室外基础设施配套工程为对象,对基于Max-npv的支付进度安排问题进行了研究。首先介绍了工程背景资料;其次构建了资金约束下的Max-npv调度问题优化模型,并求解获得满意支付进度安排;最后对理论求解结果与实际情况进行对比分析,项目净现值提升幅度为17.8%,项目最大化资金缺口得到改善。研究为项目支付进度管理定量化决策提供了依据。     

Interactive multiobjective optimization with NIMBUS for decision making under uncertainty

We propose an interactive method for decision making under uncertainty, where uncertainty is related to the lack of understanding about consequences of actions. Such situations are typical, for example, in design problems, where a decision maker has to make a decision about a design at a certain moment of time even though the actual consequences of this decision can be possibly seen only many years later. To overcome the difficulty of predicting future events when no probabilities of events are available, our method utilizes groupings of objectives or scenarios to capture different types of future events. Each scenario is modeled as a multiobjective optimization problem to represent different and conflicting objectives associated with the scenarios. We utilize the interactive classification-based multiobjective optimization method NIMBUS for assessing the relative optimality of the current solution in different scenarios. This information can be utilized when considering the next step of the overall solution process. Decision making is performed by giving special attention to individual scenarios. We demonstrate our method with an example in portfolio optimization.