掘进机截割头辅助设计软件的研究与开发

针对目前国内掘进机截割头设计大多凭经验进行以及截割负载的非线性、时变性和强耦合等特点,通过对纵轴式掘进机截割头的分析与研究,建立了截割头负载的瞬态动力学模型;基于VC＋＋和MATLAB联合开发了用于掘进机截割头设计和负载计算的计算机辅助设计软件。应用此软件可以获得截割头载荷波动曲线及波动系数、生成截割头瞬时负载的文本及截割头三维参数化实体模型,以评价截割头设计的合理性并进一步指导截割头的优化设计;解决了掘进机截割头设计中盲目缩放几何尺寸及其负载计算因人而异造成设计与计算结果迥异的问题;为新型截割头的研发及对现有机型的改进提供了新的方法和手段。软件界面友好、操作简单、方便实用,使基于科学方法的截割头计算机辅助设计在工程中的应用和推广成为可能。     

连续采煤机截齿截割能力的分析

为了确定连续采煤机截齿截割能力和其对煤岩的适应性,由截割电动机的功率求得连续采煤机截齿的平均截割力,对镐形齿进行截割实验,然后比较截割力的实验测定值与理论值,给出了适于截齿截割煤岩的截割阻抗,并计算分析了滚筒直径、滚筒的转速、截割功率和同时工作齿数对单个截齿截割力的影响。     

基于数字流域模型的多沙粗沙区产沙计算

黄河难以治理的症结是水少沙多，水沙不平衡。根据多年治黄实践，黄河中游多沙粗沙区的治理是黄土高原水土流失治理的重点，模拟计算多沙粗沙区的侵蚀产沙量意义重大。本文利用数字流域模型框架建立了黄土高原多沙粗沙区产流产沙数学模型，模型在岔巴沟小流域进行参数率定。应用率定后的模型计算了黄土高原多沙粗沙区1967、1978、1983、1994、1997五个典型年份汛期的产流产沙量，得到了多沙粗沙区的汛期径流深分布图和产沙模数分布图。计算结果能够较好地解释黄河流域的“少水多沙”现象，为多沙粗沙区的水土保持工作提供了科学依据。     

基于数字流域模型的多沙粗沙区侵蚀产沙计算

黄河难以治理的症结是水少沙多，水沙不平衡．根据多年治黄实践，黄河中游多沙粗沙区的治理是黄土高原水土流失治理的重点，模拟计算多沙粗沙区的侵蚀产沙量意义重大．利用数字流域模型框架建立了黄土高原多沙粗沙区产流产沙数学模型，模型在岔巴沟小流域进行参数率定．应用率定后的模型计算了黄土高原多沙粗沙区1967，1978，1983，1994和1997年这5个典型年份汛期的产流产沙量，得到了多沙粗沙区的汛期径流深分布图和产沙模数分布图．计算结果能够较好地解释黄河流域的“少水多沙”现象，为多沙粗沙区的水土保持工作提供了科学依据．     

薄液膜表面蒸发对降液膜传热和传质的影响

对实验结果的分析和界面质扩散量级的估算表明，降液膜表面存在着可观的过度蒸发现象，理论分析指出：表面张力引发的“毛细诱导面蒸发”是这一过度蒸发的驱动力。通过关联实验数据，得到了“有效毛细半径”的表达式，将这一表达式与表面蒸发率的计算式结合得到了“毛细诱导界面蒸发”的计算式，并以此式完善了碑已地出的液膜临界热流率的预测式，对比表明，本预测式的相对偏差比已有的其他预测式的低得多。     

连续采煤机工作面硬质包裹体分布的模拟研究

短壁工作面上硬质包裹体的分布直接影响连续采煤机的截割阻力、机器振动、工作噪音和截割的经济效益。文章在假定包裹体的几何形状为旋转椭球体的情况下,对长轴尺寸服从均匀分布、正态分布、指数分布、威布尔分布、伽玛分布和贝塔分布下的硬质包裹体在煤层中的分布进行了计算机模拟,并分析了各种情况的特征,为了解连续采煤机工作面硬质包裹体的分布、研究其截割过程和机器的工作性能创造了条件。     

层叠式锂离子电池展向温度分布的分析解及基于分析解的热设计优化

大型锂离子动力电池的热相关问题是限制其在电动汽车上大规模应用的主要问题之一.单体电池的热模型是进行电池热设计、改善电池热特性的重要工具.根据热模型的求解方法,可分为数值解和分析解两类.在现有文献的研究中,数值解占据了主要地位.但是,分析解因具有计算量小、可实现设计变量的全局优化等优点,在电池热设计和电池组热管理系统中可发挥重要作用.例如,在电池热设计中,分析解可全面考察多个设计参数连续变化下对电池热特性的影响,以进行多设计参数下的全局优化.本文首先对一款大型层叠式锂离子电池进行了数值热模拟和实验验证,数值热模拟的结果与多枚热电偶的实验测量结果吻合良好;然后,基于数值热模拟的结果提取了层叠式电池温度分布和产热率分布的主要特点,进而假设温度呈展向平面分布、产热率均匀分布;针对简化后的电池热问题,利用双重积分变换方法提出了分析解;最后,使用分析解开展了电池的热设计优化工作,讨论了不同电芯尺寸和极耳布置方案下的电池热特性.     

非恒定流作用下的推移质泥沙输移实验研究

非恒定流条件下的推移质运动研究无论是在泥沙运动理论还是在实际工程应用中,都具有重要的意义.基于波流水槽实验,对不同速度偏度的非恒定流作用下的推移质运动开展研究.主要通过泥沙粒径、速度偏度等因素对输沙率影响分析,探讨了非恒定流作用下的均匀沙与非均匀沙的运动情况,阐述了恒定流与非恒定流对输沙率影响的差异性,建立非均匀沙输移粗细质量比公式.在此基础上开展理论推导,从受力机理上对实验过程进行了分析.实验结果和理论分析表明,相对于恒定流,非恒定流作用下的泥沙颗粒更易起动和输移.     

基于句法分析的评价搭配抽取及其倾向性分析

提出一种新的基于句法分析的方法可以提取出评价搭配.通过对大量的商品评论进行句法分析,得到了常用的评论模式集合.依靠这些模式对评价搭配进行抽取.同时,构建了一种映射集合,可以映射出隐式评价对象.对于评价对象的倾向性判别,通过hownet构建了情感种子词典,采用SO-PMI方法计算出其极性,并计算出极性强度.实验结果表明,该方法对于评价搭配的抽取和极性分析具有较好的精确率和召回率.     

高孔率金属材料表观电阻率的计算公式

根据高孔率金属材料的结构特征建立几何模型 ,运用几何方法和有关电学概念 ,简便地推导了具有均匀结构的高孔率材料电阻率与孔率的数学关系 ,由此得出通过孔率这个易知量来计算高孔率材料电阻率的公式 .以泡沫镍为例的应用证明 ,该理论式与实测结果基本一致     

交叉学科研究推动了生物无机化学学科的发展

本文分为七部分，第一部分对生物无机化学学科发展进行历史回顾；第二部分从回顾史实中用实例表明生物无机化学的研究始终瞄准金属离子和生物配体控制生命过程中的化学问题；第三部分是介绍当今国际上研究核酸领域的争论焦点；第四部分是报导我们设计和合成了作为人工核酸酶的一系列新的配体以及许多不同金属的功能配合物；第五部分是讨论用动力学、热力学和DFT计算方法研究配合物和DNA相互作用的键合机制以及十多种影响因素；第六部分进一步报导配合物的生物功能和它们的应用探索，最后一部分提出在核酸领域的某些新的发展方向和途径。我们进一步提出了配合物的结构与DNA的作用机制以及它们的生物功能之间的规律性。通过配合物的结构改变去调控和改变配合物对DNA键合性质和生物功能。     

Notiz zur Vermehrungsrate der stabilen Bevölkerung

Summary A method for the calculation of the approximate value of the natural rate of increase is presented, when the maternity frequency of females is varied.     

A comparison of approximate Bayesian forecasting methods for non‐Gaussian time series

We present the results on the comparison of efficiency of approximate Bayesian methods for the analysis and forecasting of non‐Gaussian dynamic processes. A numerical algorithm based on MCMC methods has been developed to carry out the Bayesian analysis of non‐linear time series. Although the MCMC‐based approach is not fast, it allows us to study the efficiency, in predicting future observations, of approximate propagation procedures that, being algebraic, have the practical advantage of being very quick. Copyright © 2000 John Wiley & Sons, Ltd.     

Dissection of the pheromone-modulated flight of moths using single-pulse response as a template

The upwind flight of male moths to conspecific females is mediated by the chemical and structural characteristics of a pheromone plume. We describe the reaction of maleCadra cautella, the almond moth, to the interception of single pulses of sex pheromone, the smallest structural units of odour plumes. Following loss of a pheromone plume, males cast, that is fly a crosswind course without progressing upwind. The response of casting males to interception of a pulse of 0.25 s duration was, after a delay of 0.21±0.07 s, to turn and briefly fly straighter upwind, resulting in average net upwind displacements of 18 cm in a 50 cm s^–1 wind. Upwind progress in the single-pulse response was the result of steering more upwind and an increase in airspeed, although average ground speed remained unchanged. During the last third of the surge, males turned crosswind, returning to casting flight. These behavioural reactions to pheromone contact and loss support the phasic-tonic model of odour-modulated flight, in which an underlying tonic counterturning rhythm, expressed upon pheromone loss, is briefly overridden by phasic upwind surges, expressed upon interception of the pheromone filament. The surge portion of the cast-surge-cast response was diminished and more crosswind if individual pulses were shorter (0.02 s), probably due to sub-optimal contact with pheromone. The cast-surge-cast response to interception of a single 0.25 s pulse was used as a template to interpret the form of flight tracks in plumes of known structure. The template matched portions of flight tracks of males flying in plumes of low pheromone pulse frequency, thus reflecting the male's pattern of pulse encounter. In plumes ensuring a high frequency of pulse interception, only the upwind surge portion of the template was expressed, resulting in nearly straight upwind flight tracks. Similar nearly straight upwind flight tracks occurred in flights along plumes of low pulse frequency with large volume. Thus flight tracks of maleC. cautella to point sources of pheromone depend on both the frequency and the size of filaments encountered.     

Model selection and forecasting for long-range dependent processes

Fractionally integrated autoregressive moving-average (ARFIMA) models have proved useful tools in the analysis of time series with long-range dependence. However, little is known about various practical issues regarding model selection and estimation methods, and the impact of selection and estimation methods on forecasts. By means of a large-scale simulation study, we compare three different estimation procedures and three automatic model-selection criteria on the basis of their impact on forecast accuracy. Our results endorse the use of both the frequency-domain Whittle estimation procedure and the time-domain approximate MLE procedure of Haslett and Raftery in conjunction with the AIC and SIC selection criteria, but indicate that considerable care should be exercised when using ARFIMA models. In general, we find that simple ARMA models provide competitive forecasts. Only a large number of observations and a strongly persistent time series seem to justify the use of ARFIMA models for forecasting purposes.     

ARARMA models for time series analysis and forecasting

Methods of time series forecasting are proposed which can be applied automatically. However, they are not rote formulae, since they are based on a flexible philosophy which can provide several models for consideration. In addition it provides diverse diagnostics for qualitatively and quantitatively estimating how well one can forecast a series. The models considered are called ARARMA models (or ARAR models) because the model fitted to a long memory time series (t) is based on sophisticated time series analysis of AR (or ARMA) schemes (short memory models) fitted to residuals Y(t) obtained by parsimonious‘best lag’non-stationary autoregression. Both long range and short range forecasts are provided by an ARARMA model Section 1 explains the philosophy of our approach to time series model identification. Sections 2 and 3 attempt to relate our approach to some standard approaches to forecasting; exponential smoothing methods are developed from the point of view of prediction theory (section 2) and extended (section 3). ARARMA models are introduced (section 4). Methods of ARARMA model fitting are outlined (sections 5,6). Since‘the proof of the pudding is in the eating’, the methods proposed are illustrated (section 7) using the classic example of international airline passengers.     

混凝土结构在施工期可靠度的模拟分析方法

结构在施工期可靠度的分析对于保证施工安全具有重要意义.由于在施工期间,结构是一个时变结构,结构抗力是一个随机过程,荷载也与使用期的不同,所以有必要研究施工期间结构的可靠度.本文结合混凝土结构在施工期的特点,建立了施工期结构可靠度的全随机模型,分析了考虑抗力随时间变化的模拟计算原理并进行了模拟计算.结果表明,本文的计算方法可以用来对精确解进行校核或验证近似解析解     

地基土上水工建筑物的抗滑动稳定

利用基坑内压板抗滑动试验成果，确定地基土抗滑动承载能力。采用地基土承受偏心荷载的最大压应力σmax控制地基土与压板的位移和抗滑动形式，可产生3种不同的最大位移面，形成8种抗滑动形式。根据地基土承受的最大压应力，提出定量确定地基土与压板抗滑动的计算摩擦阻力的方法和设计抗滑动的4个数值计算公式，分析预测可能发生的最大位移面和抗滑动形式。对三河闸、高良涧进水闸、三河船闸3座已建水工建筑物的抗滑稳定性分析表明，计算成果符合实物工况。     

大数据背景下的信号处理

宽带信号、高维信号、高分辨信号以及多传感器组网技术的快速发展,使得信号采集数据增长率高于数据存储增长率和信号处理速度增长率,信号处理进入了大数据时代．本文指出了大数据背景下的信号处理的关键问题．对于多传感器组网具有的多样性和复杂性的海量信号数据,必须进行信息融合．本文介绍了信号融合的主要模型方法,分析了信息融合技术的发展趋势．智能传感网技术能降低对信号处理和通信容量的要求,有效地在大数据中提取有价值数据．本文给出了智能传感器的基本结构,阐述了智能传感器的计算方法．结合大数据容量信号对高速实时处理的要求,介绍了高速数字信号处理芯片以及高性能硬件平台发展现状,展望了高速信号处理核心技术的发展动向．     

Seasonal adjustment and kalman filtering: Extension to periodic variances

This paper reviews the relations between the methods of seasonal adjustment used by official statistical agencies and the ‘model-based’ methods that postulate explicit stochastic models for the unobserved components of a time series and apply optimal signal extraction theory to obtain a seasonally adjusted series. The Kalman filter implementation of the model-based methods is described and some recent results on its properties are reviewed. The model-based methods employ homogeneous or time-invariant models that assume in particular that the autocovariance structure does not vary with the season. Relaxing this leads to the class of models known as periodic models, and an example of a seasonally heterosceclastic unobserved-components ARIMA (SHUCARIMA) model is presented. The calculation of the standard error of a seasonally adjusted series via the Kalman filter is extended to this periodic model and illustrated for a monthly rainfall series.