沙尘暴对人体健康的影响及防治措施

沙尘暴是我国北方主要的灾害性天气。沙尘天气可造成烟尘与粉尘携带细菌侵入人体呼吸道,沉积在人体的肺部,引发呼吸道疾病并被肺泡吸收进入血液循环,导致其他器官疾病,危害人的身体健康。本文从沙尘暴天气的形成及对人体健康影响入手,提出了指导性的防治措施。     

Tourist Perceptions of Climate Change: A Study of International Tourists in Zanzibar

A study was conducted in Zanzibar, Tanzania, in order to understand tourist perceptions of climate change, the importance of climate for travel decisions, and the likely consequences of ongoing climate change for travel decisions. The results show that climatic characteristics of destinations are important, though not the only factor shaping travel decisions. Under a scenario of climate change, certain climate variables, such as more rain, storms, and higher humidity are also likely to negatively influence travel decisions, rather than higher temperatures alone, which are not necessarily perceived as negative. Regarding the contribution of travel to climate change, the study reveals that leisure tourists in Zanzibar are largely unaware of their impact on the natural environment, while the analysis of stated travel behaviour shows that they frequently travel by air. Overall, the results indicate that travel flows might change in more complex ways than currently assumed, and that a small share of high-intensity air travellers is responsible for a considerable environmental impact in terms of climate change.     

Agricultural disaster payments in the southeastern US: do weather and climate variability matter?

Governments around the world are forced to react to disasters caused by weather. The agricultural sector is particularly susceptible to weather extremes and adverse climate conditions. In the US, agricultural disaster payments account for a significant part of total agricultural subsidies. The payments, and their distribution, are more important in the areas most affected by disastrous weather events, usually coinciding with areas of pronounced impact of the El Nino Southern Oscillation (ENSO). In this article, the impact of weather and climate, as well as some economic variables, on disaster payments is analysed using county level data from four states in the southeastern United States. The results suggest that weather and climate variables explain most of the crop disaster payments at the county level while socioeconomic variables do not, suggesting that advancements in weather and climate forecasts could be helpful in planning for disaster compensation.     

试析人类耗用能源对气候变暖的贡献

在对地球气候变暖原因的探讨中，人们较注意“温室气体”的贡献，但与“温室气体”排放几乎同时进行的巨额热量的释放也是不应 忽视的；由205个国家和地区在1年内消耗的商品能源量数据。计算出每年释放的热量相当于地球接受30分钟的太阳辐射量，在绝热情况下可使全球陆地2m厚的表层、全球海洋2m深的水体和全球大气温度提高0.06℃；对上述结果进行了讨论。     

Can (unusual) weather conditions in New York predict South African stock returns?

This paper investigates the explanatory power of certain weather variables, measured as deviations from their monthly averages, in a leading international financial trading centre, i.e., New York, for South African stock returns, over the daily period January 2nd, 1973 to December, 31, 2015. The empirical results highlight that these unusual deviations of weather variables have a statistically significant negative effect on the stock returns in South Africa, indicating that unusual weather conditions in New York can be used to predict South African stock returns, which otherwise seems to be highly unpredictable. In fact, a forecasting exercise recommends that a trading rule that considers those weather variables through a GARCH modelling approach seems to outperform the random walk model and thus beat the market.     

模式V加密敌我识别系统

本文介绍了模式V加密敌我识别系统的特点，以及工作原理和系统构成。     

收发分置相控阵雷达直达波抑制技术

分析了收发分置数字阵列相控阵雷达中直达波问题,研究了收发 分置数字阵列相控阵雷达中直达波抑制方法,根据收发分置数字阵列相控阵雷达的工作方式 、信号处理流程等特点以及雷达的实际应用,可采用收发隔离、数字波束形成零点抑制、异 频滤波、自适应对消及脉冲压缩增益6个环节进行直达波抑制,理论分析和仿真结果表明所 给出的直达波抑制方法能有效解决收发分置数字阵列相控阵雷达直达波干扰问题。     

基于支持向量回归的现代气象雷达寿命预测

为了准确地预测气象雷达使用寿命, 提高气象雷达运行可靠性、安全性和可维护性, 提出了一种新的基于多元回归的气象雷达使用寿命预测框架。在该框架内,采用了支持向量 回归(SVR)方法来求解气象雷达使用寿命的多元回归问题;提出了基于SVR的气象雷达特征参 数选择FSSSVR（Feature Subset Selection SVR）算法去掉冗余和无效的特征参数。实验结 果表明,基于SVR方法的预测算法能够准确地预测气象雷达的使用寿命,能够为雷达全寿命 周期管理提供参考依据。     

基于射频隐身的采样周期和辐射功率控制方法研究

为进一步提高雷达的射频隐身能力,合理分配相控阵雷达的工作参数,在目标跟踪时,对雷达的采样周期和辐射功率控制方法进行研究。首先,根据目标运动状态的不同,对雷达采样周期与辐射功率自适应设计方法进行分析,在满足系统跟踪性能要求的前提下,建立了控制参数的优化模型;然后,利用粒子群算法优化自适应采样周期和自适应辐射功率等参数,有效地降低了跟踪性能误差,提高了雷达系统的射频隐身性能。与传统的雷达采样周期和辐射功率算法进行了仿真比较,结果表明所提的算法取得了较好射频隐身效果。     

利用分数阶Fourier变换抑制高频地波雷达中线性调频干扰

高频地波雷达(HFGWR)受到严重的射频干扰影响。单频射频干扰在接收信号中体现为高强度的线性调频信号,从而污染所有距离元。为抑制射频干扰,通过分析其频率特征,使用分数阶傅里叶变换（FRFT）将原始信号转换到分数阶傅里叶域,对射频干扰对应的谱峰置零,达到抑制干扰的目的。该方法的优点在于抑制射频干扰的同时无损干扰位置处的回波信号,无需重构信号。实测数据分析表明：FRFT不仅能有效抑制射频干扰,信噪比提高可达10 dB以上,而且其计算复杂度较小,满足雷达实时工作要求。