越库作业调度问题及其启发式算法研究

主要研究两台机器环境下的以加权完工时间和为目标函数的越库调度问题。首先针对两机器越库调度问题进行研究与分析,给出该问题最优解的若干性质;其次,基于最优解的性质,提出求解该问题的启发式算法,并在此基础上对所给算法进行改进;最后,通过数值实验与动态规划算法比较,证明所给算法及其改进算法的有效性。     

Panel unit root tests under cross-sectional dependence

In this paper alternative approaches for testing the unit root hypothesis in panel data are considered. First, a robust version of the Dickey-Fuller t -statistic under contemporaneous correlated errors is suggested. Second, the GLS t -statistic is considered, which is based on the t -statistic of the transformed model. The asymptotic power of both tests is compared against a sequence of local alternatives. To adjust for short-run serial correlation of the errors, we propose a pre-whitening procedure that yields a test statistic with a standard normal limiting distribution as N and T tends to infinity. The test procedure is further generalized to accommodate individual specific intercepts or linear time trends. From our Monte Carlo simulations it turns out that the robust OLS t -statistic performs well with respect to size and power, whereas the GLS t -statistic may suffer from severe size distortions in small and moderate sample sizes. The tests are applied to test for a unit root in real exchange rates.     

Linking Public Investment to Private Investment. The Case of Spanish Regions

Public investment constitutes one of the main instruments of regional policies. The existence of a direct link between infrastructure and regional income per capita is usually accepted. Literature also describes a positive effect of public investment on private capital accumulation. This paper seeks to provide new empirical evidence on this latter relationship for the case of Spanish regions over the period 1965–1997 using panel data methodology. The results show a positive effect of productive and social public investment (especially in education) on private investment. The spillover effects generated by the productive infrastructures located in other regions do not seem to encourage the private investment in neighbouring regions. Public consumption and interest rate exert a negative influence on private capital accumulation. These results are robust to changes in the econometric specification.     

Gender differences in self‐employment

This paper examines the factors that influence transitions into self‐employment, paying particular attention to gender differences. We find that: (i) men are more responsive to the wage differential between wage/salaried employment and self‐employment; (ii) liquidity constraints are more important for men; and (iii) the link between father's self‐employment status and the probability of self‐employment is stronger for men. Taken together, these results suggest that, for women, self‐employment is a closer substitute for part‐time work and labour‐market inactivity than it is for men. We attribute such differences to the different labour market opportunities and occupational strategies of women.     

Testing separability of public consumption in household decisions

In this paper we propose a sequential strategy, based on the microeconomic approach of the demand theory, in order to test for separability between private and public consumption. The aim of the present work is to verify, using a conditional almost ideal demand system, whether the different components of public consumption exert conditioning effects on the allocative structure of private spending. The empirical estimation of the model and the separability tests are developed for both a demand system in five functional categories of private spending, and for a demand system in six categories, where the private expenditures on those goods and services which can also be offered by the public sector are enclosed in a single functional category. The results of the separability tests, obtained using UK data for the 1974–2000 period, show that public individual consumption plays an important role in modifying consumer choices, while public collective consumption does not affect private consumption behaviours. The relationships between the different components of private spending and public individual consumption are both of substitutability and complementarity; in particular, we find that public individual consumption and the corresponding private expenditures on ‘Health, education, recreation and social protection’ are complements.     

民事与行政争议交叉案件审理现状、存在问题及对策分析——以南宁为视角

对民事与行政争议交叉案件的审理,各地人民法院司法实务上处理不一,方式多种多样,其原因可归结为立法规定的缺失与理论研究的不足两个方面;各自为政的处理方式,带来了诸多弊端.为了公正、高效地处理好这类案件,既要借鉴他国的处理经验,同时又要构建符合中国法文化传统的交叉案件的处理机制.     

Diversification, Ownership and Control of Swedish Corporations

We study the short‐ and long‐term valuation effects of Swedish takeovers. Using a sample of 93 bidding firms that acquired 101 targets between 1980 and 1995, we find that diversifying acquisitions lead to a negative market reaction and deterioration of the operating performance of the bidder. Announcement and performance gains in each of the three years following the acquisition occur only when bidders expand their core rather than their peripheral lines of business. Our findings suggest that focused acquisitions lead to greater synergies and operating efficiencies than diversifying acquisitions. Intra‐group acquisitions, however, show that bidders do not realise significant gains whether they adopt diversifying or focusing investment strategies by purchasing firms controlled by the Wallenberg and SHB conglomerate groups. Intra‐group targets realize significant gains regardless bidder's investment strategy. Finally, the evidence does not support the view that intra‐conglomerate acquisitions are associated with expropriation of minority shareholders. However, they appear to enhance the control rights of large shareholders of the bidding firm.     

The Determinants of Corporate Trade Credit Policies in a Bank‐dominated Financial Environment: the Case of Finnish Small Firms

This paper examines trade credit policies of small firms operating in a bank‐dominated environment (Finland). We find that creditworthiness and access to capital markets are important determinants of trade credit extended by sellers. The level of purchases is positively correlated with the level of accounts payable. Larger and older firms and firms with strong internal financing are less likely to use trade credit, whereas firms with a high ratio of current assets to total assets, and firms subject to loan restructurings use it more. Negative loan decisions by financial intermediaries increase and a close bank‐borrower relationship decreases the probability that a firm does not take advantage of trade credit discounts.     

The Original Maturity of Corporate Bonds: The Influence of Credit Rating,Asset Maturity,Security, and Macroeconomic Conditions

We examine the determinants of the new issue maturity of corporate bonds. As credit rating decreases, new bond issues have longer maturities, but substantial variation in maturity within each rating class remains. We seek to explain the variation of new issue maturity within credit classes. We find that asset maturity, security covenants, and macroeconomic conditions influence the new issue maturity of bonds within rating categories.     

Technological diversity,related diversification,and firm performance

Previous findings that related diversification creates value have been called into question over concerns about methodology and measures. Reviewing existing theory to consider how a firm's knowledge base interacts with its product market activity, I address several of these concerns by creating a measure of technological diversity based on citation‐weighted patents. The measure indicates a firm's opportunity for corporate diversification based on economies of scope in valuable knowledge assets, is defined for both single‐ and multibusiness firms, and is not correlated with more fundamental aspects of diversification, such as the number of businesses in the corporate portfolio. Evidence from a large sample of firms shows the positive relationship between diversification based on technological diversity and market‐based measures of performance, controlling for R&D intensity and capital intensity as further indicators of the type of assets underlying diversification. Results hold when controlling for the endogeneity of diversification and performance in a cross‐sectional sample or when controlling for unobserved factors using panel data. Copyright © 2006 John Wiley & Sons, Ltd.