LT码新型度分布及其在电力线通信中的应用

Luby变换(Luby Transform,LT)码作为信道编码应用于电力线通信(Power Line Communication,PLC)，可实现电信号的可靠传输。度分布对LT码编译码性能的影响至关重要。为了得到更优的度分布，首先调整二进制指数分布(Binary Exponential Distribution,BED)中的度数比例，获得一种译码性能更优的改进的二进制指数分布(Improved BED,IBED)。然后，根据IBED在冗余度较小时译码成功率高，而冗余度增大后鲁棒孤子分布(Robust Soliton Distribution,RSD)的译码性能表现更佳的特点，通过求和归一化的方式将IBED与RSD两种度分布的优势进行有机结合，提出一种新型二进制鲁棒孤子分布(Binary RSD,BRSD)。仿真结果表明，与其他方法及传统的RSD相比，采用新度分布进行LT编码，可明显降低译码开销，并节约编译码耗时。将新型度分布应用于基于LT码的PLC系统中，能有效地抑制PLC信道中各种噪声对电信号的干扰，并提高通信效率。     

Factors affecting households’ seafood purchasing decisions in Auckland,New Zealand: an empirical analysis

This paper uses the binary choice model to identify the factors that are significantly influencing the household purchase decisions of seafood products for home consumption in Auckland, New Zealand. It is found that ‘quality’ and ‘cooking easiness’ are the main product attributes that significantly influence households’ choices of seafood in Auckland. Also, the representative household has shown a strong preference for fresh and other alternative seafood products, including processed, smoked and canned, over frozen products. Retail outlets are found to be more attractive to the household purchasing seafood for home consumption. The New Zealand seafood industry may find this baseline study useful as a guide to developing future research structure on the domestic market.     

人民币均衡汇率、汇率错位与出口的关系

运用1978～2005年的数据，分别计算了人民币均衡汇率水平和汇率错位程度，并运用E-G两步法、误差修正模型和二元Logit模型对人民币均衡汇率、汇率错位与出口之间的关系进行了实证分析。     

测算企业营销能力的二次相对评价法

随着营销重要性的日益显现,营销能力成为研究的热点。本文在区分营销能力跟营销实力的基础上,结合二次相对评价方法,提出了基于DEA模型的营销能力的评价方法,在营销业绩的动态变化中测算营销能力。     

An international comparison of the determinants of retail gross margins

In this paper we compare the results of applying a new economic framework for the analysis of retail gross margins to 1982 interindustry retail data for France, Germany, and the U.S. Use of the same theoretical framework and econometric methodology separately for each of the three bodies of data yields robust empirical regularities with respect to functional form and the role of distribution services in explaining retail gross margins. An interesting feature of these results is that they arise despite substantial differences in classification and in the retail environment of the three countries.We thank E. Hoffnar and P. MacNeill for excellent research assistance. We acknowledge the financial support of INSEAD's R&D department for project R2135. We also thank the CSC at Maryland for support. Earlier versions of this paper were presented at the MIT Northeast Marketing Colloquium, the Simon Graduate School of Management at the University of Rochester, the Graduate School of Business at the University of Chicago, the Yale School of Organization and Management, the School of Business Administration at the University of Washington, and the Bureau of Economics of the Federal Trade Commission. We thank the participants in these seminars for their constructive criticisms. We are especially indebted to Peter Rossi of the University of Chicago, who provided us with helpful written comments, and to Herr Krockow of the Statistisches Bundesamt Wiesbaden, who provided us with unpublished data.     

Heterogeneous returns to chemical fertilizer at the intensive margins: Insights from Nepal

Increased fertilizer use is considered important for agricultural development in low-income countries. Promoting increased use of chemical fertilizer by lowering its price may be ineffective if demand is price inelastic. In theory, the price elasticity of demand depends on the returns to its use, but the evidence is scarce. Furthermore, while returns are often estimated for small changes in chemical fertilizer use, returns to larger changes in its use (intensive margins) are less understood. Through the inter-zonal comparisons in Nepal, we provide indicative evidence that greater returns to chemical fertilizer are associated with greater price elasticities of demand. Moreover, the evidence suggests that returns at the intensive margins, rather than returns to small changes, may largely account for inter-zonal differences in returns to chemical fertilizer within Nepal. The results suggest that better understanding the returns at the intensive margins is critical for effective agricultural inputs policies in developing countries.     

农户收入分化对林地流入与流出意愿影响研究

以辽宁省409户样本农户问卷调查为基础,采用描述性统计分析农户收入分化在农户年龄层次、受教育程度、家庭劳动力数量等方面的差异化特征,并运用二元Logistic回归模型分别讨论收入水平分化、收入结构分化、二者交互项对农户林地流转综合意愿、流入意愿、流出意愿的差异化影响。结果表明:农户收入水平分化对林地综合流转意愿、林地流入意愿具有显著正向影响;农户收入结构分化对农户林地流出意愿具有显著正向影响;农户收入水平分化与结构分化交互项对农户林地综合流转意愿、林地流出意愿具有显著正向影响。因此,需要关注农户收入分化因素;做好收入分化因素的有效识别;充分认识收入分化因素对农户林地流入与流出意愿的差异影响;把握分化特征,有针对性提高林地流转意愿。     

英语读写素质研究中的二元理论分析

英语读写素质是习得读写能力并形成读写体验的过程。读写素质主要由分析能力、结合社会文化能力、话语分类能力、读写实践能力、记忆能力、情感反应、思辨能力和隐喻理解能力等因素构成。本文首先应用二元理论中的集对分析理论分析了句子、语法和词语,英语句子具有同异性,英语语法中时态的相关性均有特定的语法表征手段,英语词语是一种约定俗成的语言单位常常附衍了一串同义词、近义词和反义词。如果用联系数来描述词语的相关度,它同时也反映出了词语的思想丰度。本文还运用博弈理论和悖论分析文章的含义及价值,最后应用模糊二元对比排序法对英语读写素质各因素进行分析,通过分析确定了各因素的重要度,将其应用于读写素质研究中具有积极作用并具一定的发展潜力。     

二叉树期权定价模式评估林业碳汇项目的价值

基于黑龙江省林业局和中国林业统计年鉴的数据,运用修正的Faustmann模型和二叉树期权定价方法分析黑龙江省黑河造林林区的碳汇价值及该项目的经济可行性。研究结果表明:经营成本负向影响项目的最终价值;碳汇价格和木材价格正向影响项目的最终价值;初始价值正向影响项目的最终价值;黑龙江省黑河造林林区项目具有较高的经济效益和生态效益。因此,相关部门应建立完善的碳汇交易市场,实施激励措施和制定林地产权制度。     

The untold story of commodity futures in China

We investigate the behavior of commodity futures risk premia in China. In the presence of retail-dominance and barriers-to-entry, the term structure and momentum premia remain persistent, whereas hedging pressure, skewness, volatility, and liquidity premia are distorted by time-varying margins and strict position limits. Furthermore, open interest, currency, and inflation premia are sensitive to institutional settings. The observed premia cannot be attributed to common risks, sentiment, transactions costs, or data-snooping, but are related to liquidity, anchoring, and regulation-induced limits-to-arbitrage. We highlight the distinctive features of Chinese futures markets and assess the challenges posed to theories of commodity risk premia.