动态均衡价格及其稳定性分析

本文讨论了动态系统中均衡价格向量的变化轨迹及其稳定性．由分析可知，当价格向量沿理想变化路变化时，价格向量最稳定；当价格向量沿非理想变化路变化时，给出了价格向量相对稳定的充要条件．     

建筑业中投标合同的统计和模糊分析

许多货物和劳务合同是依据密标的拍卖签订的。在建筑业中，有报价选择特权的承包商决定工程的标价常常是一个艰难的过程。一般公认的标价办法是实际成本加毛利。本文运用主因素分析法和回归分析法来研究香港的竞争性承包商的投标成效，同时也用模糊线性回归来研究投标过程的结构。最后，根据香港建筑业投标数据库，比较了统计和模糊回归分析这两种方法的结果。     

Infinite Memory Expectations in a Dynamic Model with Hyperbolic Demand

In this study we will research the dynamics shown by a cobweb-type model with hyperbolic demand, sigmoidal supply and with backward-looking mechanism of expectation creation, whereby the new state of the system is obtained from all the previous states observed by weighted arithmetical mean with exponentially decreasing weights in the region. The study herewith presented aims at confirming the existence of a stabilising effect due to the presence of infinite memory since, with all the other conditions begin the same, a memory rate > exists at which market equilibrium is a sink. An unstable system, therefore, becomes stable in the presence of sufficiently resistant expectations with infinite historical memory, although this transition to stability is accompanied by the onset of chaos. The resulting effect, therefore is one of qualitative destabilisation, that is with reference to the qualitative dynamic performance produced, associated to a quantitative stabilisation, that is to say with reference to the decreasing width of the invariant sets within which relevant dynamics occur.     

The oscillation of stock price by majority orienting traders with investment position

We consider an interacting particle system for the stock price fluctuation. The change of the stock price with a feedback by the price considering the herding behavior (majority orienting behavior) of traders, gives the van der Pol equation as a deterministic approximation. Considering the investment position of each trader, we introduce the delayed van der Pol equation. The history of investment positions, for example sell or buy, of each trader for a stock makes a memory effect, which is modeled by using the time retardation. The delayed van der Pol equation model seems to be natural and explains typical phenomena, for example triangle pattern, volatility jumps, price jumps and price trends, known for the time series of a stock price.     

商住综合用地评估的加价模型

从商业路线价、住宅用地级别价和商住综合用地路线价之间的相互关系出发,建立商住综合用地评估的每米加价模型,给出利用“每米加价”评估商住综合用地的步骤,并结合实例,用剩余估价法对模型的应用结果进行了验证。     

土地统一收购价格内涵界定研究

本文以土地统一收购是一种“强制性的买卖关系”为假设前题,通过对需要收购土地类型的产权界定和增值收益形成原因分析,认为收购价格内涵构成是与被收购土地原使用者对土地拥有的权利和利益保持一致的土寺现实用途价格,收购价格内涵构成中不包括各种安置补偿费,也不包括土地的发展权价格。     

Time-Varying Parameters Prediction

This paper develops a method of adaptive modeling that may be applied to forecast non-stationary time series. The starting point are time-varying coefficients models introduced in statistics, econometrics and engineering. The basic step of modeling is represented by the implementation of adaptive recursive estimators for tracking parameters. This is achieved by unifying basic algorithms—such as recursive least squares (RLS) and extended Kalman filter (EKF)—into a general scheme and next by selecting its coefficients with the minimization of the sum of squared prediction errors. This defines a non-linear estimation problem that may be analyzed in the context of the conditional least squares (CLS) theory. A numerical application on the IBM stock price series of Box-Jenkins illustrates the method and shows its good forecasting ability.     

Stochastic orders and their applications in financial optimization

Stochastic orders and inequalities are very useful tools in various areas of economics and finance. The purpose of this paper is to describe main results obtained so far by using the idea of stochastic orders in financial optimization. Especially, the emphasis is placed on the demand and shift effect problems in portfolio selection. Some other examples, which are not related directly to optimization problems, are also given to demonstrate the wide spectrum of application areas of stochastic orders in finance.     

Buckling of composite panels subjected to biaxial loading

Buckling loads and modes of flat composite laminates were measured and compared with theory. Laminates were subjected to simply supported boundary conditions and biaxial loading. Displacements were measured both mechanically using dial gages and optically using shadow moiré. Predictions were obtained numerically using the Galerkin method. Buckling loads were measured during 49 tests. Overall, measurements confirmed expected trends. Buckling loads increased with an increase in transverse tensile loading as predicted. Measured buckling modes were also well predicted, including an observed increase in mode number with an increase in transverse tensile loading. Measured buckling loads were not as well predicted, and substantial error was encountered during individual tests. Discrepancies between measurement and prediction are reported in terms of the percentage error in prediction. The average and standard deviation in percentage error for 49 measurements was 1.6 percent ±15.4 percent. These discrepancies are thought to be due to specimen imperfections, difficulties in simulating truly simply supported boundary conditions and/or nonuniform loading of the composite panels.     

Subtraces and shadow chains

Given a finite algebra A, such that the variety omits type 1, it is shown that type 5 will occur in only if type 5 already occurs in the free algebra on two generators. The technique generalizes to give the decidability of other typesets, and provides a simpler alternative to what had previously required Maltsev conditions. Received October 9, 1998; accepted in final form January 29, 1999.