拖拉机室内台架试验技术现状与展望

作为拖拉机研发的重要验证手段，拖拉机室内台架试验可方便高效地为拖拉机模拟各种工况下的性能表现。首先探究动力总成控制技术、负载模拟技术、试验数据处理技术和试验结果评价技术4种拖拉机室内台架试验关键技术，结合试验技术的最新研究进展，对4种技术进行详细的阐述和分析。接着从动力总成控制算法、负载模拟算法、试验数据处理方法、试验结果评价指标体系4个方面对拖拉机室内台架试验技术进行讨论与展望。最后得出对动力总成算法进行优化、提高动态负载模拟精度、保持试验数据处理方法的前沿性、对试验结果综合客观评价是拖拉机室内台架试验技术的发展趋势，以期为我国拖拉机室内台架试验技术的发展提供参考。     

人工神经网络在电力系统短期负荷预测中的应用

根据电力系统短期负荷变化的特性，提出BP模型在实际负荷预测应用中的方法和步骤．对BP网络结构、样本空间、收敛性等作了有针对性的研究．结果表明：多层神经网络应用于电力系统短期负荷预测是可行和有效的．其预报结果比传统的负荷预测方法更准确、经济、效果更好．     

步进电机扭矩测量试验台系统的设计

专用电机扭矩测量仪器精度高，但价格昂贵，操作复杂，长时间使用会出现误差。步进电机扭矩测量试验台系统采用单相交流电机作负载，使用标准扭矩仪对该系统进行标定来对待测调速电机进行扭矩测量。为此，介绍了一种电机扭矩测量系统的构成与工作原理。该系统以单片机为核心，组成扭矩测量与显示系统，可以较好地实现电机扭矩在线测量，具有较好的经济效益。     

有源负载恒温槽性能分析

本文阐述了有源负载恒温槽的工作原理，推导了描述其静态特性的缩减因数表达式，并对这种恒温槽的性能和应用作出了评价。     

两端不等弯矩作用下薄壁梁柱的弯扭屈曲

本文采用Ｒａｙｌｅｉｇｈ－Ｒｉｔｚ法求解两端不等弯矩作用下单轴对称开口薄壁截面梁柱弯扭屈曲临界荷载，分析中考虑了三种常见的边界条件以及屈曲前变形的影响，将本文弯扭屈由临界荷载理论值与试验值比较，吻合较好。     

哈达门国家森林公园游客量动态预测

根据哈达门国家森林公园的票房数据，应用灰色系统理论建立旅游量灰色动态模型。基此，对哈园游客量进行了中短期预测，其预测检验精度为９３．７２。旨在对该园建设、管理等项决策提供科学依据。     

The influence of sampling scheme and interpolation method on the power to detect spatial effects of forest birds in Ontario (Canada)

Spatial ecology is becoming an increasingly important component of resource management, and the general monitoring of how human activities affect the distribution and abundance of wildlife. Yet most work on the reliability of sampling strategies is based on a non-spatial analysis of variance paradigm, and little work has been done assessing the power of alternative spatial methods for creating reliable maps of animal abundance. Such a map forms a critical response variable for multiple scale studies relating landscape structure to biotic function. The power to reconstruct patterns of distribution and abundance is influenced by sample placement strategy and density, the nature of spatial auto-correlation among points, and by the technique used to extrapolate points into an animal abundance map. Faced with uncertainty concerning the influence of these factors, we chose to first synthesize a model reference system of known properties and then evaluate the relative performance of alternative sampling and mapping procedures using it. We used published habitat associations of tree nesting boreal neo-tropical birds, a classified habitat map from the Manitou Lakes area of northwestern Ontario, and point count means and variances determined from field studies in boreal Canada to create 4 simulated models of avian abundance to function as reference maps. Four point sampling strategies were evaluated by 4 spatial mapping methods. We found mixed-cluster sampling to be an effective point sampling strategy, particularly when high habitat fragmentation was avoided by restricting samples to habitat patches >10 ha in size. We also found that of the 4 mapping methods, only stratified ordinary point kriging (OPK) was able to generate maps that reproduced an embedded landscape-scale spatial effect that reduced nesting bird abundance in areas of higher forest age-class fragmentation. Global OPK was effective only for detecting broader, regional-scale differences. This revised version was published online in July 2006 with corrections to the Cover Date.     

Modelling Plant Disease Epidemics

An epidemic is the progress of disease in time and space. Each epidemic has a structure whose temporal dynamics and spatial patterns are jointly determined by the pathosystem characteristics and environmental conditions. One of the important objectives in epidemiology is to understand such spatio-temporal dynamics via mathematical and statistical modelling. In this paper, we outline common methodologies that are used to quantify and model spatio-temporal dynamics of plant diseases, with emphasis on developing temporal forecast models and on quantifying spatial patterns. Several examples of epidemiological models in cereal crops are described, including one for Fusarium head blight.     

Improving cereal yield forecasts in Europe – The impact of weather extremes

The impact of extreme events (such as prolonged droughts, heat waves, cold shocks and frost) is poorly represented by most of the existing yield forecasting systems. Two new model-based approaches that account for the impact of extreme weather events on crop production are presented as a way to improve yield forecasts, both based on the Crop Growth Monitoring System (CGMS) of the European Commission. A first approach includes simple relations – consistent with the degree of complexity of the most generic crop simulators – to explicitly model the impact of these events on leaf development and yield formation. A second approach is a hybrid system which adds selected agro-climatic indicators (accounting for drought and cold/heat stress) to the previous one. The new proposed methods, together with the CGMS-standard approach and a system exclusively based on selected agro-climatic indicators, were evaluated in a comparative fashion for their forecasting reliability. The four systems were assessed for the main micro- and macro-thermal cereal crops grown in highly productive European countries. The workflow included the statistical post-processing of model outputs aggregated at national level with historical series (1995–2013) of official yields, followed by a cross-validation for forecasting events triggered at flowering, maturity and at an intermediate stage. With the system based on agro-climatic indicators, satisfactory performances were limited to microthermal crops grown in Mediterranean environments (i.e. crop production systems mainly driven by rainfall distribution). Compared to CGMS-standard system, the newly proposed approaches increased the forecasting reliability in 94% of the combinations crop × country × forecasting moment. In particular, the explicit simulation of the impact of extreme events explained a large part of the inter-annual variability (up to +44% for spring barley in Poland), while the addition of agro-climatic indicators to the workflow mostly added accuracy to an already satisfactory forecasting system.     

基于LM算法的BP神经网络的电力负荷短期预测

清代书院课艺总集多为连续出版物，或具有连续出版物的刊行初衷。刊期短则一季，多则一年或数年。经费充足与否，会影响刊期。发表周期多为一年至五年，也有十余年的。用稿率以10%~20%居多，偶见“关系稿”。时文的用稿标准是“清真雅正”。题目多为官师所拟。一般全文刊登，也偶有“论点摘编”。多经润色，并附录评点。有的以袖珍本刊行，有的宣称“翻刻必究”，标出定价，附载广告。稿费已在膏火费中预支，优秀作品可被转载。从本质属性和诸多要素来看，书院课艺总集实开今日“大学学报”、“学术集刊”之先河。