the role of software process simulation modeling in software risk management: a systematic review

Univ SE Calif, Ctr Syst & Software Engn, ABB, Microsoft Res, IEEE, ACMSIGSOFT, N Carolina State Univ Comp Sci

一种基于软件过程仿真的软件项目风险管理方法

软件开发是一项高度复杂的活动，涉及到人员、过程、产品、客户等多种因素，这些因素中存在着大量的不确定性，在软件项目中表现为风险。风险能够给软件项目带来严重的危害，造成工程延期、成本超支、软件产品质量低下等各种问题，因此软件项目管理者必须对软件项目风险进行有效的管理。 软件项目风险管理是软件项目管理中不可或缺的重要组成部分，但是在实际的软件项目中，软件项目风险管理却常常被忽略，很多项目管理者凭自己的经验和直觉来管理软件项目风险。造成这种现象的原因除了软件企业的文化因素外，主要是因为软件项目管理者缺少操作层面上有效的风险管理方法和工具。 软件过程仿真能够分析软件过程的动态行为特性，预测软件过程执行的性能，是一种很好的软件项目分析和管理工具。软件过程仿真已经广泛应用于包括风险管理在内的软件项目管理的多个方面。多项研究已经表明软件过程仿真作为一种有效的风险管理方法和工具，能够很好的支持软件项目风险管理过程。 为了指导软件项目管理者使用软件过程仿真进行风险管理，本文提出了一种基于软件过程仿真的软件项目风险管理方法（SPS-RM）。该方法是一种使用软件过程仿真进行软件项目风险管理的通用方法框架，实现了“风险监控风险影响分析风险解决”的风险管理过程，并且为每个风险管理活动都提供了相应的过程仿真模型。SPS-RM方法还包括使用软件过程仿真进行风险管理的通用步骤，以及建立和分析过程仿真模型的一般方法，并为模型、步骤和方法都提供了详细的指导说明。 本文的主要贡献包括： 对软件过程仿真在软件项目风险管理中的应用和研究现状进行了调研。调研的目的是为了获得当前的研究进展，找出目前存在的问题，并指出未来可能的研究方向。调研的结果为本文的研究方向提供了很好的指导，也为本文的具体研究内容提供了良好的理论和实际依据。 提出了一种基于软件过程仿真的软件项目风险管理方法（SPS-RM）。该方法是一个使用软件过程仿真进行软件项目风险管理的通用方法框架，其目的是指导广大的软件项目管理者使用软件过程仿真有效的管理软件项目风险。SPS-RM是本文的核心方法，后面对两个具体风险的研究都是基于该方法进行的。 提出了需求变更风险分析仿真方法（RVSim）。需求变更是一种在软件项目中常见的、对软件项目影响较大的风险。本文基于SPS-RM方法对需求变更风险进行研究，提出了需求变更风险分析仿真方法。该方法以需求的横向和纵向跟踪信息为基础，对需求变更的处理过程进行仿真，能够量化的给出单个需求变更或者一系列需求变更对软件项目的时间和工作量的影响，帮助项目管理者更好的理解和管理需求变更风险。 提出了人员离职风险解决仿真方法（LF-ETRS）。人员离职是软件项目中的另一个重要风险。本文基于SPS-RM方法对人员离职风险进行研究，提出了人员离职风险解决仿真方法。该方法的主要特点是首次在对软件项目中的人员进行建模时同时考虑了人的学习和遗忘行为，因此能够更加准确的预测人员替代所需的时间和成本。另外，该方法还考虑了除人员替代外的其他解决措施，通过对多种解决措施进行建模和仿真，项目管理者可以根据项目的实际情况和仿真结果选择最合适的措施来解决人员离职风险。

地震P-S波时差耦合作用的斜坡崩滑效应研究

China locates between the circum-Pacific and the Mediterranean-Himalayan seismic belt. The seismic activities in our country are very frequent and so are the collapses and slides of slope triggered by earthquakes. Many collapses and slides of slope take place mainly in the west of China with many earthquakes and mountains, especially in Sichuan and Yunnan Provinces. When a strong earthquake happening, the damage especially in mountains area caused by geological hazards it triggered such as rock collapses, landslides and debris flows is heavier than that it caused directly. A conclusion which the number of lives lost caused by geological hazards triggered by a strong earthquake in mountains area often accounts for a half even more of the total one induced by the strong earthquake can be made by consulting the statistical loss of several representative earthquakes. As a result, geological hazards such as collapses and slides of slope triggered by strong earthquakes attract wide attention for their great costs. Based on field geological investigation, engineering geological exploration and material data analysis, chief conclusions have been drawn after systematic research on formation mechanism, key inducing factors, dynamic characteristics of geological hazards such as collapses and slides of slope triggered by strong earthquakes by means of engineering geomechanics comprehensive analysis, finite difference numerical simulation test, in-lab dynamic triaxial shear test of rock, discrete element numerical simulation. Based on research on a great number of collapses and landslides triggered by Wenchuan and Xiaonanhai Earthquake, two-set methods, i.e. the method for original topography recovering based on factors such as lithology and elevation comparing and the method for reconstructing collapsing and sliding process of slope based on characteristics of seism tectonic zone, structural fissure, diameter spatial distribution of slope debris mass, propagation direction and mechanical property of seismic wave, have been gotten. What is more, types, formation mechanism and dynamic characteristics of collapses and slides of slope induced by strong earthquakes are discussed comprehensively. Firstly, collapsed and slided accumulative mass is in a state of heavily even more broken. Secondly, dynamic process of slope collapsing and sliding consists of almost four stages, i.e. broken, thrown, crushed and river blocked. Thirdly, classified according to failure forms, there are usually four types which are made up of collapsing, land sliding, land sliding-debris flowing and vibrating liquefaction. Finally, as for key inducing factors in slope collapsing and sliding, they often include characteristics of seism tectonic belts, structure and construction of rock mass, terrain and physiognomy, weathering degree of rock mass and mechanical functions of seismic waves. Based on microscopic study on initial fracturing of slope caused by seismic effect, combined with two change trends which include ratio of vertical vs. horizontal peak ground acceleration corresponding to epicentral distance and enlarging effect of peak ground acceleration along slope, key inducing factor of initial slope fracturing in various area with different epicentral distance is obtained. In near-field area, i.e. epicentral distance being less than 30 km, tensile strength of rock mass is a key intrinsic factor inducing initial fracturing of slope undergoing seismic effect whereas shear strength of rock mass is the one when epicentral distance is more than 30 km. In the latter circumstance, research by means of finite difference numerical simulation test and in-lab dynamic triaxial shear test of rock shows that initial fracture begins always in the place of slope shoulder. The fact that fracture strain and shear strength which are proportional to buried depth of rock mass in the place of slope shoulder are less than other place and peak ground acceleration is enlarged in the place causes prior failure at slope shoulder. Key extrinsic factors inducing dynamic fracture of slope at different distances to epicenter have been obtained through discrete element numerical simulation on the total process of collapsing and sliding of slope triggered by Wenchuan Earthquake. Research shows that combined action of P and S seismic waves is the key factor inducing collapsing and sliding of slope at a distance less than 64 km to initial epicenter along earthquake-triggering structure. What is more, vertical tensile action of P seismic wave plays a leading role near epicenter, whereas vertical shear action of S seismic wave plays a leading role gradually with epicentral distance increasing in this range. On the other hand, single action of P seismic wave becomes the key factor inducing collapsing and sliding of slope at a distance between 64 km and 216 km to initial epicenter. Horizontal tensile action of P seismic wave becomes the key factor gradually from combined action between vertical and horizontal tensile action of P seismic wave with epicentral distance increasing in this distance range. In addition, initial failure triggered by strong earthquakes begins almost in the place of slope shoulder. However, initial failure beginning from toe of slope relates probably with gradient and rock occurrence. Finally, starting time of initial failure in slope increases usually with epicentral distance. It is perhaps that the starting time increasing is a result of attenuating of seismic wave from epicenter along earthquake-triggering structure. It is of great theoretical and practical significance for us to construct towns and infrastructure in fragile geological environment along seism tectonic belts and conduct risk management on earthquake-triggered geological hazards by referring to above conclusions.