基于RF-LightGBM算法在风机叶片开裂故障预测中的应用

针对SCADA系统采集的数据繁杂,难以从原始数据判别工作中风机叶片开裂状态的问题,提出了一种对风机叶片状态进行分类预测的随机森林(RF)算法与LightGBM算法结合的模型。首先对SCADA数据进行预处理,特征变换,采用RF算法对特征进行重要性排序;然后利用清洗后的数据训练该分类预测模型,利用K折交叉验证法对模型进行验证调优;最后用测试数据集对叶片状态进行预测,依靠F1-score指标对模型性能进行评价。实验结果表明,数据处理后,模型性能明显提高,较XGBoost与GBDT算法分别提高了11%、16%,与传统的叶片状态识别方法相比,该算法能够更加快速精准的在线预测出风机叶片开裂状态,为风电场对风机叶片状态监测检修提供更可靠的参考依据。     

利用推力和F/P_1值对潜水搅拌器进行精确选型

定量分析了水池中的系统损失,依据所需推力和潜水搅拌器额定推力这两大主要因素对潜水搅拌器进行精确选型,并利用F/P1值和生命周期成本比较了不同搅拌器的工作效率,选择了最优方案.     

Cross-border transport infrastructure and aid policies

We investigate resource allocation concerning the provision of cross- border transport infrastructure, which is used for trade of goods between two neighboring countries. Since the level of infrastructure is sub-optimal under the circumstances that two governments choose the levels of infrastructure independently, we focus on the role of foreign aid to improve the efficiency of infrastructure provision. In this paper, we examine the welfare effects of aid policies, and show that aid can make both countries better off, i.e., Pareto improvement. Furthermore, Pareto improvement is more likely if the stage of development in recipient country is very low or sufficiently high.     

TSP203在齐岳山隧道中的应用及误差产生原因

分析了TSP203的探测原理,比较了TSP203对齐岳山隧道平导F5断层的预报与实际工程揭示的情况,结合一些经验、教训分析了预测不准确的原因和施工中的注意事项,以保证隧道工程的顺利施工。     

Distance,time since foreign entry,and productivity spillovers from foreign direct investment

This paper investigates the effect of foreign direct investment on the productivity of local manufacturing firms in Romania. We decompose traditional country‐wide spillover measures in different components according to both proximity between foreign and domestic firms and time‐since‐foreign‐entry. We find larger and faster spillover effects for local suppliers of foreign firms at shorter distance, driven mainly by recent foreign entrants. Irrespective of distance, foreign firms of medium maturity generate backward spillover effects that fade away with longer presence. A positive effect on local competitors is not significantly affected by distance, but requires the presence of mature foreign firms.     

An equation by any other name is still the same: on spatial econometrics and spatial statistics

Statistics is a branch of mathematics concerned with the collection, quantification, analysis, interpretation, and presentation of real-world data, and the use of probability theory to estimate population parameters with these data. Spatial statistics is a subset of statistics that is concerned with handling the special problems associated with geographically distributed data, which include spatial point patterns, regional and lattice measurement aggregations, irregularly spaced site-specific measurements on a surface, and image analysis. Meanwhile, econometrics is concerned with the application of statistical methods to the study of economic data and problems. When coining the term spatial econometrics in 1979, Paelinck and Klaassen characterized it as a subset of econometrics that is concerned with the role of spatial dependence in regional economic model response and explanatory variables, asymmetries in spatial relationships, the specification of geographic structure governing spatial interactions, and the explicit modeling of space. We outline and discuss principal similarities (e.g., testing for the presence of spatial autocorrelation) and differences (e.g., map generalization) between spatial statistics and spatial econometrics. In doing so, our goal is to help clarify past, present, and future relationships between these two subfields.     

上海F1国际赛车场清水混凝土施工技术

根据F1国际赛车场项目采用大体量、多类型的清水混凝土结构的特点,着重介绍了 清水混凝土控制、模板设计、预制清水混凝土看台板的安装及产品保护等方面的施工技术措施。     

Rates of experimental microbiological contamination of fish exposed to polluted water

Fish inhabiting fecally polluted bodies of water are often used for human consumption. Such fish can be contaminated by enteric human pathogens and may pose a potential risk to public health. Controlled experiments with 132 fish of 100 g average weight were conducted to evaluate the rate of contamination of various tissues of fish (tilapia hybrids). The fish were exposed to E. coli introduced into the ambient water at concentrations of up to 10⁶ cfu/ml. Additional experiments were conducted with diluted wastewater containing Aeromonas, enterococci, fecal coliform and F+ coliphages. In another experiment poliovirus I was also added. The highest bacterial concentrations were recovered from the digestive tract (DT), some 5–24 h following exposure, with DT levels essentially similar to those in the inoculated water. In the E. coli experiments, geometric mean levels of about 10² cfu/cm² were recovered from the skin, 26 cfu/g in the spleen and 10² cfu/g in the liver. Most of the muscle samples were not contaminated. Greater contamination was not found under conditions of stress such as high organic load, a water temperature of 37°C or low levels of dissolved oxygen.     

原状、挤密黄土地基有限元法计算及分析

通过对原状、挤密黄土地基的有限元法计算及分析，探讨了原状黄土地基的变形、强度特征以及挤密对它的影响，得到了一些有益的结论。     

紫坪铺泄洪洞穿越断层段新奥法设计与数值仿真分析

本文基于新奥法的基本原理 ,对紫坪铺水利工程 1 # 泄洪洞穿越 F3断层段的支护设计方案进行了有限元数值仿真分析和优化设计。分析结果表明 ,按照常规的支护不能保证围岩、支护的稳定。本文经过 4个支护方案的设计与仿真分析 ,提出了较为理想的支护方案 ;该支护方案已为工程实际所采用 ,取得了良好的实际效果。