重视语言教与学中的“情感过滤”

本文在简要论述什么是第二语言习得及二语习得理论对语言教师实践的重要意义的基础上,着重探讨了二语习得中情感因素的研究成果,特别是"情感过滤"现象的存在对外语教与学的启示.     

复合电晕场中粉尘粒子的荷电机制

分析了场致荷电和扩散荷电的特点,讨论了复合电晕场中粉尘粒子的荷电率     

Integrating risk assessment and life cycle assessment: a case study of insulation.

Increasing residential insulation can decrease energy consumption and provide public health benefits, given changes in emissions from fuel combustion, but also has cost implications and ancillary risks and benefits. Risk assessment or life cycle assessment can be used to calculate the net impacts and determine whether more stringent energy codes or other conservation policies would be warranted, but few analyses have combined the critical elements of both methodologies In this article, we present the first portion of a combined analysis, with the goal of estimating the net public health impacts of increasing residential insulation for new housing from current practice to the latest International Energy Conservation Code (IECC 2000). We model state-by-state residential energy savings and evaluate particulate matter less than 2.5 microm in diameter (PM2.5), NOx, and SO2 emission reductions. We use past dispersion modeling results to estimate reductions in exposure, and we apply concentration-response functions for premature mortality and selected morbidity outcomes using current epidemiological knowledge of effects of PM2.5 (primary and secondary). We find that an insulation policy shift would save 3 x 10(14) British thermal units or BTU (3 x 10(17) J) over a 10-year period, resulting in reduced emissions of 1,000 tons of PM2.5, 30,000 tons of NOx, and 40,000 tons of SO2. These emission reductions yield an estimated 60 fewer fatalities during this period, with the geographic distribution of health benefits differing from the distribution of energy savings because of differences in energy sources, population patterns, and meteorology. We discuss the methodology to be used to integrate life cycle calculations, which can ultimately yield estimates that can be compared with costs to determine the influence of external costs on benefit-cost calculations.     

Multivariate temporal disaggregation with cross-sectional constraints

Multivariate temporal disaggregation deals with the historical reconstruction and nowcasting of economic variables subject to temporal and contemporaneous aggregation constraints. The problem involves a system of time series that are related not only by a dynamic model but also by accounting constraints. The paper introduces two fundamental (and realistic) models that implement the multivariate best linear unbiased estimation approach that has potential application to the temporal disaggregation of the national accounts series. The multivariate regression model with random walk disturbances is most suitable to deal with the chained linked volumes (as the nature of the national accounts time series suggests); however, in this case the accounting constraints are not binding and the discrepancy has to be modeled by either a trend-stationary or an integrated process. The tiny, compared with other driving disturbances, size of the discrepancy prevents maximum-likelihood estimation to be carried out, and the parameters have to be estimated separately. The multivariate disaggregation with integrated random walk disturbances is suitable for the national accounts aggregates expressed at current prices, in which case the accounting constraints are binding.     

柴油机喷油嘴测控系统融合实训室建设研究

在柴油机喷油嘴测控系统使用过程中,不同的终端、软件系统、算法体系等方面存在差异,成为其融合(互联互通)的一大阻碍,因此迫切需要一个平台来保证互联互通工作的顺利运行。依托现有校企合作协同创新基地,借助立项的省市级科技计划研究平台,开展柴油机喷油嘴测控系统融合实训室的建设与实践。通过阐明实训室的建设目的与工作定位,提出实训室具体建设方案,并从测试平台、管理制度以及人才队伍建设等方面进行探讨。在建设发展中,实训室为柴油机喷油嘴测控系统的融合提供测试等服务,取得了初步的成效。     

A modification of the Whittaker–Henderson method of graduation

This paper presents a modified Whittaker–Henderson (WH) Method of Graduation. After giving a closed-form solution, we show that it is of practical use because it provides not only a smoothed series identical to that of the WH graduation, but also an extrapolation beyond the sample limit of current data. In addition, we introduce two other penalized least squares problems and show that they provide the same results as those of the modified WH graduation.     

现代大伦敦的空气污染成因与治理——基于生态城市视野的历史考察

19世纪以来英国的工业化和城市化进程,既创造了巨大的物质财富,也给人类社会带来沉重的负面效应,其中空气污染就是代价之一,成为生态城市建设的重大障碍。伦敦首先对以烟雾型的空气污染成因进行分析与治理,接着对汽车尾气中的二氧化硫和铅污染进行治理。新世纪以来,则着重开展对二氧化氮和可吸入悬浮颗粒的监测与治理。从空气立法到大伦敦市长的空气质量策略,从拥堵费到低排放区,从以自行车为代表的绿色出行到对工地街道扬尘的治理,表明了伦敦市政府对空气污染的治理越来越深入全面,治理空气污染的手段也在推陈出新。     

一种双星定位与捷联惯性的融合方法

捷联惯性导航系统的主要缺点是导航定位误差随时间增长,双星定位系统是一种区域性卫星定位系统,可输出较高精度的水平位置,然而双星定位系统具有位置滞后与用户隐蔽性差的特点,针对其位置滞后现象研究了捷联惯性导航系统与双星定位系统进行组合的滤波方法,提出了其量测噪声的统计模型,同时设计其组合的时机以弥补系统的隐蔽性差的问题。仿真结果表明该滤波方法可行,具有较好的工程应用价值。     

A UNIFIED FRAMEWORK FOR MODELLING WILDLIFE POPULATION DYNAMICS†

This paper proposes a unified framework for defining and fitting stochastic, discrete‐time, discrete‐stage population dynamics models. The biological system is described by a state‐space model, where the true but unknown state of the population is modelled by a state process, and this is linked to survey data by an observation process. All sources of uncertainty in the inputs, including uncertainty about model specification, are readily incorporated. The paper shows how the state process can be represented as a generalization of the standard Leslie or Lefkovitch matrix. By dividing the state process into subprocesses, complex models can be constructed from manageable building blocks. The paper illustrates the approach with a model of the British grey seal metapopulation, using sequential importance sampling with kernel smoothing to fit the model.     

缩口四角ω形燃烧系统的研究

本文在缩口四角ω形燃烧室的设计及试验的基础上,阐述了紊流扰动对燃烧过程的影响。指出在燃烧室设计中运用紊流运动,注意燃烧室、进气涡流与喷油规律恰当的配合,在保持小型直喷式柴油机经济性好的同时降低排放中的有害成份是可以做到的。