一种基于神经网络提取旋波材料参数的新方法

提出了一种从测试的S参数中提取旋波材料参数的新方法——神经网络法。针对旋波材料参数的自由空间测试方法，本文采用BP神经网络来构建映射模型，利用不同算法对网络进行训练，从而获得所需的网络。结果表明，该方法计算速度快、精度高，解决了求解非线性方程组解的模糊性问题，确保了测试结果的可靠性。该方法所构建的网络可用于材料测试后旋波材料参数的快速提取。     

An analysis of operations efficiency in large-scale distribution systems

This research applies Data Envelopment Analysis (DEA) methodology to evaluate the efficiency of units within a large-scale network of petroleum distribution facilities in the USA. Multiple inputs and outputs are incorporated into a broad set of DEA models, yielding a comprehensive approach to evaluating supply chain efficiency. This study empirically separates three recognized, important and yet different causes of performance shortfalls which have been generally difficult for managers to identify. They are: (1) managerial effectiveness; (2) scale of operations and potential for a given market area (and efficiency of resource allocation given the scale); and (3) understanding the resource heterogeneity via programmatic differences in efficiency. Overall, the efficiency differences identified raised insightful questions regarding top management’s selection of the appropriate form and type of inputs and outputs, as well as questions regarding the DEA model form selected.     

关于“义乌指数”的思索

“义乌指数”于2006年10月22日正式发布，它全面反映了义乌小商品价格波动及市场活跃程度。“义乌指数”的发布具有重要的意义，但同时也存在不完善的方面，需要进一步的发展。     

Ordinal efficiency and dominated sets of assignments

Using lotteries is a common tool for allocating indivisible goods. Since obtaining preferences over lotteries is often difficult, real-life mechanisms usually rely on ordinal preferences over deterministic outcomes. Bogomolnaia and Moulin (J. Econom. Theory 19 (2002) 623) show that the outcome of an ex post efficient mechanism may be stochastically dominated. They define a random assignment to be ordinally efficient if and only if it is not stochastically dominated. In this paper we investigate the relation between ex post efficiency and ordinal efficiency. We introduce a new notion of domination defined over sets of assignments and show that a lottery induces an ordinally efficient random assignment if and only if each subset of the full support of the lottery is undominated.     

Price Clustering on the Tokyo Stock Exchange

This paper examines price clustering on the Tokyo Stock Exchange (TSE). Regardless of tick and lot size, prices ending in zero and five are the most popular. The TSE has no market makers or direct negotiation between traders; therefore, clustering is not explained by collusion or negotiation. Our evidence supports the attraction hypothesis. Clustering also extends to order book depth. There is evidence of strategic trading behavior as traders place orders one price tick better than zero and five to avoid queuing orders at prices ending in these digits. Strategic trading behavior declined and clustering increased when the market became anonymous.     

Analysis of Covariance with Non-normal Errors

Analysis of covariance techniques have been developed primarily for normally distributed errors. We give solutions when the errors have non-normal distributions. We show that our solutions are efficient and robust. We provide a real-life example.     

Can we obtain realistic parameter estimates for the ‘protection for sale’ model?

Abstract.  In the Grossman and Helpman (1994) model of endogenous trade protection, sectoral lobbies try to influence an incumbent government that maximizes a weighted sum of political contributions and aggregate welfare. We empirically investigate this model using U.S. and Turkish data. Our specification is more tightly tied to theory than those in existing studies. Additionally, we assume all specific‐factor owners to be organized into different lobbies. These changes, validated by hypothesis tests, yield more realistic parameter estimates of the government's concern for aggregate welfare and of the fraction of population organized into lobbies.     

The maximum entropy median in the presence of an outlier

When a random sample of size n from a standard normal population is contaminated by a normal outlier with either a different mean or a different variance, the maximum entropy median outperforms the sample median in terms of squared-error loss. The only exception is when n=3 and the outlier mean or variance is sufficiently different.     

The Ability to Minimize the Timing of New Product Development and Introduction: An Examination of Antecedent Factors in the North American Automobile Supplier Industry

The importance of overall timing in the new product development and the new product commercialization processes has been widely recognized in the literature. We examined 14 firm-level practices, later reduced to four factors, that influence the ability to minimize new product development and introduction times overall relative to competitors. The factors are (1) human resource management, (2) synergistic integration, (3) supplier closeness, and (4) the design-manufacturing interface. An empirical study of the North American automobile supplier industry found some support for the four-factor model of antecedents to timing ability: synergistic integration and supplier closeness were both significantly related to development and introduction time minimization ability. The implications of these findings for product development managers and academic researchers are discussed.