我国建筑钢结构设计规划及发展

发展钢结构建筑有利于实现国民经济可持续发展,近10多年来钢结构发展很快,但钢结构应用范围涵盖面与发达国家相比还相差甚远,中国是建筑业大国,国内、国外的建筑市场十分广阔。如何扩大钢结构应用范围,是建筑、结构工程师在建筑业可持续发展的"后建筑时代"也就是低碳、节能、环保建筑中所面临的继承和创新的挑战。我国钢结构大量在建筑工程中应用可以说是从广州新白云国际机场开始,发展到今天在许多航站楼、会展中心、体育场馆、奥运场馆、工业厂房、高层建筑直至现在的高铁站房。本文对此展开一个阐述。     

Do people consider an acceptable travel time? Evidence from Berkeley,CA

This paper explores the extent to which people identify an acceptable travel time for each trip they want to make and investigates the primary characteristics of this behavioural threshold. We assume that an acceptable travel time is defined through utilitarian processes that are related to cognitive and affective evaluations of travel that develop throughout a person’s lifetime. We apply a mixed methods approach to explore our hypothesis, based on semi-structured in-depth interviews with a stratified, according to commuting mode, random sample of 20 individuals living in Berkeley, CA. Our results support the validity of the acceptable travel time concept and offer (a) initial evidence on its variation to the travel mode and sociodemographic characteristics and (b) insights into people’s perceptions, attitudes, feelings and experiences about their travel. Thus, our results can contribute to a better understanding of individuals’ travel decisions and valuation of travel time and can inform time–space and accessibility research.     

PRICING FOR LARGE POSITIONS IN CONTINGENT CLAIMS

Approximations to utility indifference prices are provided for a contingent claim in the large position size limit. Results are valid for general utility functions on the real line and semi‐martingale models. It is shown that as the position size approaches infinity, the utility function's decay rate for large negative wealths is the primary driver of prices. For utilities with exponential decay, one may price like an exponential investor. For utilities with a power decay, one may price like a power investor after a suitable adjustment to the rate at which the position size becomes large. In a sizable class of diffusion models, limiting indifference prices are explicitly computed for an exponential investor. Furthermore, the large claim limit arises endogenously as the hedging error for the claim vanishes.     

Kuhn’s Theorem for extensive form Ellsberg games

We propose the notions of mixed and behavioral Ellsberg strategies for extensive form games and prove that these strategies are outcome-equivalent if and only if mixed Ellsberg strategies satisfy a certain rectangularity condition. In addition, we show that not only the profile of Ellsberg strategies must be appropriately chosen but also the extensive form must satisfy further restrictions beyond those implied by perfect recall in order to ensure that each player will respect his ex ante strategy choice with the evolution of play.     

Advantageous redistribution with three smooth CES utility functions

We present a parametric example of three-country advantageous redistribution with two Cobb–Douglas utility functions and one CES utility function for which the elasticity of substitution is 1/2. This paper indicates that the possibility of advantageous redistribution strongly depends on the three countries’ taste patterns, endowment distributions, and the elasticity of substitution. In particular, we will show with specific examples that greater difference between the donor and recipient’s taste patterns and a lower elasticity of substitution can increase the chance of advantageous redistribution.     

BEHAVIORAL PORTFOLIO SELECTION: ASYMPTOTICS AND STABILITY ALONG A SEQUENCE OF MODELS

We consider a sequence of financial markets that converges weakly in a suitable sense and maximize a behavioral preference functional in each market. For expected concave utilities, it is well known that the maximal expected utilities and the corresponding final positions converge to the corresponding quantities in the limit model. We prove similar results for nonconcave utilities and distorted expectations as employed in behavioral finance, and we illustrate by a counterexample that these results require a stronger notion of convergence of the underlying models compared to the concave utility maximization. We use the results to analyze the stability of behavioral portfolio selection problems and to provide numerically tractable methods to solve such problems in complete continuous‐time models.     

On sustained economic growth with wealth effects

In a discounted one-sector convex model of optimal economic growth where utility may depend on both consumption and capital stock, I derive necessary and sufficient conditions for sustained growth (unbounded expansion of capital and consumption). Conditions for bounded growth and extinction are also outlined. Optimal paths may be non-monotone. Sustained growth may occur even though the asymptotic marginal productivity is less than the discount rate and may require the initial capital stock to be above a critical level. The behavior of the marginal rate of substitution between consumption and capital plays a crucial role in the conditions.     

基于古诺模型的四种市场的社会福利

市场根据垄断程度的不同。可以分为完全竞争、垄断竞争、寡头垄断和完全垄断市场四种类型。基于古诺模型，用博弈论方法研究n个厂商市场情形的总产量、价格、总收益和消费者剩余并把它们归纳为统一的公式。从四种市场情形总产量和价格的特点推出其供给曲线的形状，进而比较其社会福利的状况。研究结果表明，随着垄断性的加强，市场的社会福利会越来越劣，完全竞争市场的社会福利最好，垄断竞争市场次之，寡头垄断市场更次，完全垄断市场的社会福利最差。     

Minimal Hellinger martingale measures of order <Emphasis Type="Italic">q</Emphasis>

This paper proposes an extension of the minimal Hellinger martingale measure (MHM hereafter) concept to any order q≠1 and to the general semimartingale framework. This extension allows us to provide a unified formulation for many optimal martingale measures, including the minimal martingale measure of Föllmer and Schweizer (here q=2). Under some mild conditions of integrability and the absence of arbitrage, we show the existence of the MHM measure of order q and describe it explicitly in terms of pointwise equations in ? ^d . Applications to the maximization of expected power utility at stopping times are given. We prove that, for an agent to be indifferent with respect to the liquidation time of her assets (which is the market’s exit time, supposed to be a stopping time, not any general random time), she is forced to consider a habit formation utility function instead of the original utility, or equivalently she is forced to consider a time-separable preference with a stochastic discount factor.