天线罩相位误差研究

目的解决在机翼天线罩内不同位置加罩引起的相位误差问题。方法从工程实际应用出发,介绍干涉仪测向原理,计算由裸天线引起的相位误差,并利用电磁仿真软件FEKO中的理想接收天线验证其正确性。提出天线-天线罩系统中天线罩会引起额外相位误差的观点,定性分析影响天线罩相位误差的主要因素,其中包括两端曲率半径差异、罩壁结构和制作工艺。天线-天线罩测向误差由裸天线和天线罩相位误差两部分组成。给出微波暗室测试结果和天线罩相位误差校正方法。结果校正后相位误差满足工程需求。结论提出的相位校正方法简单可行,实验方法具有可操作性和重复性。     

北京市能源消费与经济增长关系的协整检验分析

采用协整分析并建立向量误差修正模型（VECM）检验了北京市1980～2008年能源消费与经济增长之间的因果关系.结果表明,北京市能源消费与经济增长之间存在长期均衡状态,体现为从经济增长到能源消费单向的因果关系.经济对能源的长期与短期弹性分别为0.44和0.12,北京市1980～2008年GDP年均每增长1%,带动能源消费增长约0.4%.经济发展对能源消费提升是滞后的,能源消费并不是经济增长的一个强的外生变量.研究结论能够对北京市制定节能减排目标以及促进区域经济发展提供重要参考依据.     

Investigation of methods for estimating hand bone dimensions using X-ray hand anthropometric data

This study examined two conversion methods, M1 and M2, to predict finger/phalange bone lengths based on finger/phalange surface lengths. Forty-one Korean college students (25 males and 16 females) were recruited and their finger/phalange surface lengths, bone lengths and grip strengths were measured using a vernier caliper, an X-ray generator and a double-handle force measurement system, respectively. M1 and M2 were defined as formulas able to estimate finger/phalange bone lengths based on one dimension (i.e., surface hand length) and four finger dimensions (surface finger lengths), respectively. As a result of conversion, the estimation errors by M1 presented mean 1.22?mm, which was smaller than those (1.29?mm) by M2. The bone lengths estimated by M1 (mean r?=?0.81) presented higher correlations with the measured bone lengths than those estimated by M2 (0.79). Thus, the M1 method was recommended in the present study, based on conversion simplicity and accuracy.     

河流污染物通量估算方法分析(Ⅰ)——时段通量估算方法比较分析

通过对河流时段通量所采用的估算方法的误差比较分析,说明了实测河流断面时段通量中时间平均离散通量的贡献;并讨论了污染源的点源、非点源类型的差别对选择年通量估算方法的影响.通过实例探讨了河流长时间通量估算方法的使用范围,对估算方法的取舍原则进行了分析.      

人因失误的机理及其可靠性研究

随着科技的发展 ,在系统安全中 ,机器设备可靠性越来越高 ,由于人本身的复杂性 ,人因失误变得愈来愈严重。本文基于人行为的原理 ,对人因失误的机理、影响人失误的因素、人行为的模型和失误模型及其可靠性的量化进行了分析 ,建立了计算人可靠性的威布尔分布模型 ,并对其参数进行了讨论 ,可用此来评价人的可靠性。     

APPLICATION OF GREY MODEL TOWARD RUNOFF FORECASTING1

ABSTRACT: A reliable forecasting model is essential in real‐time flood forecasting for reducing natural damage. Efforts to develop a real‐time forecasting model over the past two decades have been numerous. This work applies the Grey model to forecast rainfall and runoff owing to the model's relative ability to predict the future using a small amount of historical data. Such a model significantly differs from the stochastic and deterministic models developed previously. Ten historical storm events from two catchment areas in northern Taiwan are selected to calibrate and verify the model. Results in this study demonstrate that the proposed models can reasonably forecast runoff one to four hours ahead, if the Grey error prediction method is further used to update the output of the model.     

Inverse modeling to estimate LNAPL plume release timing

Methodologies are presented for dating releases of light nonaqueous phase liquids (LNAPLs) using an inverse modeling approach with simple analytical models. Models for LNAPL plume migration are presented to predict LNAPL plume velocity in the unsaturated and saturated zones as a function of basic soil and fluid properties. A relative mobility factor is introduced for LNAPL movement at the water table that depends primarily on the van Genuchten n parameter (related to the breadth of the soil pore size distribution) and the magnitude of water table fluctuations. Estimated LNAPL plume velocities compare reasonably with more rigorous numerical models, which may be used in cases where data availability warrant the greater effort entailed.Two methods of estimating release timing and its uncertainty are investigated. A direct estimation method is described that determines travel time for a single observed travel distance based on estimated soil and fluid properties. Release date uncertainty may be determined using the first order (FO) or Monte Carlo (MC) methods. The second method for estimating release date involves nonlinear parameter estimation utilizing distance vs. time measurements and other data.A case study is presented for a field site where independent estimates of release timing were obtained from a numerical modeling analysis. Release timing estimates based on direct inversion of the analytical timing model agree well with the numerical analysis. Results for a second field site indicate that release date confidence limits estimated by the FO method, assuming log-normally distributed travel times, are close to values determined by the MC method, which makes no assumption regarding the form of the travel time probability distribution.Results for a hypothetical problem indicate that LNAPL velocity and travel time may be accurately estimated if sufficient data on travel distance vs. time are available. Incorporating prior information on relevant soil and fluid properties into the objective function reduces the uncertainty in release date if prior estimates are accurate. However, biased prior estimates may lead to over- or underestimation of release date uncertainty. Simultaneous estimation of soil and fluid properties and release date is possible if prior information is available to condition the parameter estimates.     

Unveiling the liaison between human capital,trade openness,and environmental sustainability for BRICS economies: Robust panel-data estimation

Global warming and greenhouse gas emissions pose severe threats to environmental sustainability. A sustainable environment is a prerequisite for long-term socioeconomic growth and human survival. Green technology is brought about by a country's economic and financial openness, and education provides knowledge to the public and labor, contributing to environmental sustainability. Thus, this research aims to unveil the liaison between human capital, trade openness, and environmental quality for Russia, Brazil, India, China, and South Africa (BRICS) countries from 1998 to 2018. Several econometric methods, including the Driscoll–Kraay standard errors and the Dumitrescu–Hurlin causality approaches, reveal long-run and causal relationships among the modelled indicators. The Driscoll–Kraay standard error results show that human capital is negatively related to carbon dioxide emissions (CO₂ emissions). Imposing high tariffs and excise duties, changing tax structures, discouraging the inflow of polluted commodities, and encouraging green trade can help BRICS combat high environmental pollution. The results show that a one-point increase in human capital in models 1 and 2 can reduce CO₂ emissions by 1.5279 and 0.1538 points, respectively. In contrast, a 1% growth in trade can lead to a rise in CO₂ emissions of 0.3731% and 0.2384%, respectively. Similarly, financial development and energy consumption result in high CO₂ emissions in the long run. Moreover, a feedback effect of the human capital index on CO₂ emissions is discovered. As a result of the findings, the government and responsible authorities should provide financial support and encourage investments in the region's energy-resourceful and sustainable green projects.     

基于VaR的我国煤炭行业金融安全影响因素分析

从金融科学、安全科学角度,提出煤炭行业金融安全的定义,认为煤炭企业融资和投资过程中的金融安全管理是我国能源安全的重要保证。可以从宏观经济状况、融资状况和投资条件3个方面分析影响煤炭行业金融安全的因素。采用金融安全管理中的VaR风险估价方法将煤炭行业金融安全影响指标进行定量化描述,运用Eviews软件构建误差修正模型分析各个影响指标与煤炭行业金融安全之间的长期、短期经济关系,明确二者之间的影响机制。CPI、资金成本率和借款率对煤炭行业金融安全的短期波动有影响;从长期来看,GDP、资金成本率和借款率指标与煤炭金融安全有着正相关关系,CPI、资产负债率和汇率与煤炭金融安全有着负相关关系。     

供电设备电气误操作的防止及应对措施

着重介绍了电气设备误操作的"五防"及应对措施.从阐述电力系统供电设备电气防止误操作的重要性人手,引人"五防"概念,诠释了防误操作装置八点基本要求,列举了目前具有防止电气误操作的器件,并针对"五防"的内涵,提出了操作性强的五条相应预防措施,在文章后段结合自身的工作实践,从八个层面详述了工作体会,特别提出了电力系统严格遵守避免误操作事故的五条禁令,从而探究出从实践上杜绝电气设备误操作事故发生的有效途径.