The distribution of stress-strain resultants in prestressed concrete portal frames

Imperial Users onl

A REPRESENTATIVE MARKET MODEL OF FARMLAND BID PRICES

A land bid-price model is formulated which integrates asset pricing models form prior studies to illustrate the singular and joint effects of ordinary and capital gains taxes, growth of returns, diseconomies of size, and risk behavior on farmland prices. An application of the model to primary data from cash grains farms illustrates that the ceteris paribus effect of increased marginal tax rates on a perpetual, growing income stream is to increase its present value. Larger farms in higher marginal tax brackets are shown to have a competitive advantage over smaller, lower tax bracket farms.Land Economics/Use,

Treasury Secretary James Baker\u27s Program for Sustained Growth for the International Debt Crisis: Three Steps Toward Global Financial Security

This comment will offer a brief overview of the factors leading up to the present international debt crisis. The second and third prongs of Secretary Baker\u27s Program for Sustained Growth will then be analyzed with particular emphasis on the roles Secretary Baker recommends that the IMF, the World Bank, and multinational commercial lending institutions play in resolving the LDC crisis. Last, actions that must be taken by the LDCs as well as LDC demands for trade liberalization will be discussed, along with the effects such trade liberalization would have on the LDC debt situation

A membrane bioreactor for biotransformations to synthesise hydrophobic chiral molecules using organic solvent nanofiltration membranes

Imperial Users onl

A general approach to temporal reasoning about action and change

Reasoning about actions and change based on common sense knowledge is one of the most important and difficult tasks in the artificial intelligence research area. A series of such tasks are identified which motivate the consideration and application of reasoning formalisms. There follows a discussion of the broad issues involved in modelling time and constructing a logical language. In general, worlds change over time. To model the dynamic world, the ability to predict what the state of the world will be after the execution of a particular sequence of actions, which take time and to explain how some given state change came about, i.e. the causality are basic requirements of any autonomous rational agent. The research work presented herein addresses some of the fundamental concepts and the relative issues in formal reasoning about actions and change. In this thesis, we employ a new time structure, which helps to deal with the so-called intermingling problem and the dividing instant problem. Also, the issue of how to treat the relationship between a time duration and its relative time entity is examined. In addition, some key terms for representing and reasoning about actions and change, such as states, situations, actions and events are formulated. Furthermore, a new formalism for reasoning about change over time is presented. It allows more flexible temporal causal relationships than do other formalisms for reasoning about causal change, such as the situation calculus and the event calculus. It includes effects that start during, immediately after, or some time after their causes, and which end before, simultaneously with, or after their causes. The presented formalism allows the expression of common-sense causal laws at high level. Also, it is shown how these laws can be used to deduce state change over time at low level. Finally, we show that the approach provided here is expressive