6.1概述 主要以承受轴向压力为主通常还有弯矩和剪力作用

4.1概述(Introduction) 一、结构中常用的梁、板是典型的受弯构件 二、梁的截面形式常见的有矩形、T形、工形、箱形、T形、∏形

项目管理是为完成一个预定的目标,而对任务和资源进行规划、组织和管理 的程序,通常需要配合时间、资源或成本方面的限制式。项目计划可以很简单 例如笔记本上列出的任务以及它们的开始和完成日期;也可以很复杂,例如包括 成千上万项任务和资源以及上百万元项目预算的项目。 大多数项目管理工作多涉及一些相同的活动,其中包括将项目分割成便于管 理的多个任务、子任务、在小组中交流信息以及追踪任务的工作进展

Interactive Complexity Complexity is a moving target The underlying factor is intellectual manageability 1. A simple\system has a small number of unknowns in its interactions within the system and with its environment 2. A system is intellectually unmanageable when the level of interactions reaches the point where they cannot be thoroughly

Programming Languages As difficult to discuss rationally as religion or politics. Prone to extreme statements devoid of data. Examples: \It is practically impossible to teach good programming to students that have had a prior exposure to BASIC; as potential programmers they are mentally mutilated beyond hope of regeneration.\(Dijkstra)

opyright Nancy Leveson, Sept. 1999 Stage 1: Forming Team members begin to discover what behaviors are acceptable Usually highly unstructured environment Attempt to identify tasks, how to accomplish them Decisions on what information is needed Hesitant participation

1. When you can measure what you are speaking about, and can express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowleage is of a meagre and unsatisfactory kind: It may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the stage of science. Lord Kelvin, a physicist

Reuse (Assume have source code, not a commercial product) Ariane 5. Therac-25. British AtC Expectation Significantly lower development costs and time. Amortize costs among all users or uses Assumptions

Formal design Reviews Associated with each of documentation phases Evaluate with respect to Customer requirements Prescribed standards and practices Contractual requirements

Outline: Software Design Goals History of software design ideas Design principles Design methods Life belt or leg iron?(Budgen)