稳压电源的自适应去火弧技术

针对传统基于继电器控制的稳压电源在带负载工作时,档位切换常常伴随火弧现象的问题,设计了一种可广泛 应用于此类稳压电源上的自适应去火弧技术：使用光耦和多级运放完成对零点和电压电流的采样;基于单片机的10量, 实现对继电器的驱动和控制;基于RCC自激震荡原理为系统提供稳定电源;设计了稳压器的完整软件系统程序,并在软 件中应用自适应去火弧算法。实验结果表明：自适应去火弧技术,能够有效地规避火弧现象的产生,并能够根据条件作 出调整。采用自适应去火弧技术的稳压系统达到了设计目标,延长了系统工作寿命。     

基于高斯图的截面数据精确分段及重构

针对反求工程中截面重构时由于分段点提取不精确造成重构结果不理想的问题,提出一种分段点精确提取方 法。基于截面数据的法向量信息构建高斯图,将分段点确定在一个区间内,根据区间端点将截面数据分为不同的特征 段;优先重构直线特征,再根据约束重构自由特征,并在自由特征重构过程中建立动态搜索模型,用二次插值法动态搜索 精确分段点。实验表明该方法提高了分段点的提取精度和截面重构的精度,重构的结果很好地还原了产品模型的初始 设计意图。     

基于G1连续的圆弧与B样条分段区间确定及重构方法

在逆向工程中,截面曲线重构质量的高低决定了能否更好地反映物体的初始设计意图。高精度分段点的提取则 是提高重构质量的关键。针对圆弧与B样条曲线重构过程中,无法确定分段点所在区间问题,提出了圆弧与B样条线 性化处理方法,并结合基于数理统计原理的分段点区间确定办法和基于黄金分割法的重构方法,提取了圆弧与B样条间 的高精度分段点。实例证明该方法能在现存数据之间搜寻精度更高的分段点。该方法有效地解决了圆弧与B样条高精 度分段点提取问题。     

省域经济洼地区域中心城市发展战略研究——以江苏淮安为例

省域经济洼地地区是实现区域协调发展的重要板块和关键区域。以江苏省淮安市为例,从战略角度审视淮安建设成为苏北重要中心城市的意义和基础,并提出淮安在区域经济和流域经济层面上两个维度的发展定位和三个方向的发展路径。通过纵向融入京沪高铁和京杭运河两条复合发展轴,横向建设淮河流域生态经济带,打造苏皖在江北地区的跨界合作示范区等战略,推动淮安苏北重要中心城市的建设和省域经济协调发展格局的形成。     

Noninformative priors for the between-group variance in the unbalanced one-way random effects model with heterogeneous error variances

For the unbalanced one-way random effects model with heterogeneous error variances, we propose the non-informative priors for the between-group variance and develop the first- and second-order matching priors. It turns out that the second-order matching priors do not exist and the reference prior and Jeffreys prior do not satisfy a first-order matching criterion. We also show that the first-order matching prior meets the frequentist target coverage probabilities much better than the Jeffreys prior and reference prior through simulation study, and the Bayesian credible intervals based on the matching prior and reference prior give shorter intervals than the existing confidence intervals by examples.     

Stress-strength reliability of exponentiated Fréchet distributions based on Type-II censored data

In this paper, we consider inference of the stress-strength parameter, R, based on two independent Type-II censored samples from exponentiated Fréchet populations with different index parameters. The maximum likelihood and uniformly minimum variance unbiased estimators, exact and asymptotic confidence intervals and hypotheses testing for R are obtained. We conduct a Monte Carlo simulation study to evaluate the performance of these estimators and confidence intervals. Finally, two real data sets are analysed for illustrative purposes.     

Estimation of geodesic tortuosity and constrictivity in stationary random closed sets

We investigate the problem of estimating geodesic tortuosity and constrictivity as two structural characteristics of stationary random closed sets. They are of central importance for the analysis of effective transport properties in porous or composite materials. Loosely speaking, geodesic tortuosity measures the windedness of paths, whereas the notion of constrictivity captures the appearance of bottlenecks resulting from narrow passages within a given materials phase. We first provide mathematically precise definitions of these quantities and introduce appropriate estimators. Then, we show strong consistency of these estimators for unboundedly growing sampling windows. In order to apply our estimators to real data sets, the extent of edge effects needs to be controlled. This is illustrated using a model for a multiphase material that is incorporated in solid oxide fuel cells.     

A general central limit theorem and a subsampling variance estimator for α‐mixing point processes

We establish a central limit theorem for multivariate summary statistics of nonstationary α‐mixing spatial point processes and a subsampling estimator of the covariance matrix of such statistics. The central limit theorem is crucial for establishing asymptotic properties of estimators in statistics for spatial point processes. The covariance matrix subsampling estimator is flexible and model free. It is needed, for example, to construct confidence intervals and ellipsoids based on asymptotic normality of estimators. We also provide a simulation study investigating an application of our results to estimating functions.     

白寿彝先生的民俗学实践与理论

白寿彝的民俗学研究表现在两个方面,一是收集整理地方文化中的民俗资料,二是进行相关的民俗现象研究。前者主要体现在对《开封歌谣集》的收集整理上,作为民国时期民俗学研究领军人物顾颉刚先生的学生,白寿彝通过编辑这部歌谣集,来反映诸多社会问题,表达对下层民众的关注,追求唤起民智的目标。后者先后体现在若干单篇论文中,其新中国成立以前论文主要是对封建迷信的歌谣观的梳理,特点是多取材于正史;其新中国成立以后论文主旨在于辨析民俗学中的传说思想,特点是取材于当代人的研究成果和充分利用传世文献,同时批评相关无学理意义的论断。这两方面的民俗学研究体现出白寿彝在民俗学理论方面的深厚修养,以及民俗学与历史学密切结合、关注下层民众、适应时代发展需要的高度自觉,至今具有一定的示范和借鉴价值。     

荷兰集成农业对我国现代农业发展的启示

我国在发展现代农业、推进社会主义新农村建设的过程中,将会长期受到现代农业生产技术特别是有机农业生产技术推行成本高、风险大的制约.荷兰通过把复杂的现代农业生产管理技术集成到农业装备中,然后把集成技术装备植入现代农业生产的各环节,很好地解决了先进农业技术推行成本高、风险大的问题.长期以来,荷兰用这种集成技术装备的办法发展园艺业、奶牛业等复杂农业,取得了世界农业强国的地位,这是很值得我国发展现代农业借鉴的.