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。     

Intraday Returns and the Frequency of Trading at the Ask on the Sydney Futures Exchange: A Research Note

This article documents and provides explanations for intraday patterns in returns for the Share Price Index (SPI) futures contract traded on the Sydney Futures Exchange (SFE). Consistent with overseas futures markets research, a positive and significant overnight return is documented. Unlike overseas futures markets, we find little evidence of an end of day price rise. Our evidence suggests that overnight returns for the SPI contract are largely driven by the way returns are typically measured, which ignores the fact that there is a significantly greater frequency of sellers at the market close and buyers at the start of the day. These patterns are consistent with hedging behaviour by futures traders with long positions in the underlying stock.     

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.     

养老基金筹集模式的实证分析

当前的养老制度改革是关注的焦点。本文首先将从介绍现存的筹集模式入手,试图换个角度来思考在人口老龄化背景下的我国养老金基金制度,实证分析模式选择对于缴费率等的影响,并基于此,讨论未来改革的方向。     

Optimising a Probabilistic Model of the Development of Play in Soccer

We present a probabilistic model based on the one developed by Hernández Mendo and Anguera (Revista de Psicologíca Social, 16(1), 71–93, 2001). Here we have tried to break down the interaction contexts that the opposing teams are able to generate and transform during the game. We are aware that a given player or team does not produce consistent behaviour in similar situations. However, a degree of uncertainty is assumed to exist regarding whether the results obtained are a specific function of the analysis used. In order to carry out this research a category system which optimized that used in the previous model was developed. This system should enable the interaction between teams to be observed within the actual play of a soccer game. A lag sequential analysis was performed on the basis of a coding of the behavioural flow. After describing the behavioural patterns obtained a probabilistic model of the development of play in soccer is proposed.     

Land use externalities, open space preservation, and urban sprawl

Parcel data on residential land conversion are used to investigate how land use externalities influence the rate of development and modify policies designed to manage urban growth and preserve open space. Several “smart growth” policies are found to significantly influence land conversion, including a development clustering policy that concentrates development and generates preserved open space. In addition to directly affecting a parcel's hazard rate of conversion, this policy is found to affect neighboring parcels' conversion by generating a positive open space externality that hastens their development. The implication that the clustering policy could generate a more sprawled pattern of development is explored using spatial simulation.     

YAWL语言及其系统的初步研究

工作流和工作流管理系统的合理应用可大大提高办公自动化的程度,而现有的工作流系统在支持工作流基本模式上存在一定的缺陷。一种新出现的YAWL语言较好地支持了工作流现有的基本模式,文章就YAWL语言及其系统的执行方法进行了初步的研究。     

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。     

论现代流通方式

流通方式是指商品由生产领域进入消费领域所采用的方法和形式的总和，现代流通方式是适应现代生产和消费的要求及流通发展要求的各种流通方式所形成的体系。流通的发展主要通过流通方式的变革体现出来，并在近一个世纪里由传统的流通方式演化为现代流通方式。发展现代流通方式是从根本上改变我国流通产业发展滞后的状况、发挥流通产业对国民经济先导作用的重要措施。     

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。