Why is the element stiffness matrix singular in a finite element formulation? 1. So that it can accomodate rigid element dis- placements without introducing spurious nodal 2 Because we made a mistake in the formula- tion the stiffness matrix should not be sin- g 3. Because we havent enforced any displace ment boundary conditions(it's a variational approach after all) Statement(1)

Strain energy and potential energy of a beam brec sedans hoMe the neutra xxis remain So Figure 1: Kinematic assumptions for a beam Kinematic assumptions for a beam: From the figure: AA'=u3(a1) Assume small deflections: B B\,BB\=3+ duy

We are going to consider the forces exerted on a material. These can be external or internal. External forces come in two flavors: body forces(given per unit mass or volume) and surface forces(given per unit area). If we cut a body of material in equilibrium under a set of external forces along a plane as shown in fig. 1. and consider one side of it we draw two conclusions: 1 the equilibrium provided by the loads from the side taken out is provided by a set of forces that are distributed among the material particles adjacent to

The work of the external forces in the spring system of the figure is given by W=B*(U1+U2+U3)(2) W=P1*U1+P2米U2+B米U3(3) None of the above statements

1叶格尔CM等著.飞机设计.杨景佐等译.北京:航空工业出版社,1986 2杨景佐,曹名编.飞机总体设计.北京:航空工业出版社,1991 3 Raymer D P. Aircraft Design: A Conceptal Approach. AlAA Education Series, 1992 4[美]雷曼尔DP著.现代飞机设计.钟定逵等译.北京:国防工业出版社,1992

案例1 1990年,阿根廷某公司应中国某公司的请求,报出镁矿石初级产品200公吨,每公吨2 150美元,即期装运的实盘。但中方接到阿方报盘,未作还盘,而是一再请求阿方增加数量, 降低价格,并延长有效期,阿方公司将数量增到350公吨,每公吨价格为CIF上海价2100 美元,有效期经三次延长,最后延长至9月25日,中方公司于9月20日来电表示接受该盘。 阿方接到该电报时,得知国际市场镁矿石价格上扬,因此决定拒绝成交,于是向中方发 电,称:“由于国际市场镁矿石价格发生变化,货物已于接到你方电报时售出。”而中方对 此拒绝接受,认为中方是在发盘有效期内接受了阿方发盘,坚持要求按发盘的条件执行合同, 阿方如不执行合同,则要赔偿中方的损失,即差价25万美元

一、本章内容概要 1.综合艺术的主要种类。 (1)戏剧艺术。从广义上讲,戏剧包括话剧、中国戏曲、歌剧、舞剧、乃至目前欧美各国影响广 泛的音乐剧等。从狭义上讲,戏剧主要是指话剧。这里所讲的戏剧即指话剧,是从狭义理解的。话剧在欧 美各国通常被称为戏剧

80年代末,正值中国市场 “疲软”之时,安利公司却决定 选择中国为新的目标市场,并于 1990年开始构思。1991年8月,安 利公司获中国政府有关部门批准 立项,1992年8月签订合同,1993 年开始在广州经济技术开发区建 设厂房、首期工程于1995年1月竣 工,每年可生产价值超过2亿美元

Index absorptance HT-54 cylindrical geometry see non-planar geometry absorption HT-57 adiabatic 0-5.0-9 Diesel cycle 2A-4 adiabatic efficiency see efficiency diffusivity ht-22 adiabatic flame temperature 2C-7 dissipation 1C-10 drag HT-24 Biot number HT-30, HT-36 black body HT-56, HT-63 see also

PARTO- PRELUDE: REVIEW OF UNIFIED ENGINEERING THERMODYNAMICS [AW pp 2-22, 32-41(see IAW for detailed SB&vw references): VN Chapter 1] 0.1 What it's all about The focus of thermodynamics in 16.050 is on the production of work, often in the form of kinetic energy(for example in the exhaust of a jet engine)or shaft power