Comparison of measured and predicted field strengths of medium frequency sky waves over short distances in Japan

Nighttime sky waves of four medium frequencies were observed at distances of not larger than about 300 km in Japan for one to two years of high and low solar activities. The sporadic E (Es) layer always appeared with high probability. Analyzing these data, the following results were obtained: 1) the measured median field strengths are different by at least more than 7 dB from full wave predicted values for the international reference ionosphere (IRI) without the Es-layer. But these agree fairly well with the full wave calculation for IRI with the Es-layer, 2) the field strength approximates the Rayleigh distribution, 3) according to the data for high solar activity, the sky wave appears rapidly after sunset, and during the two to six hours after sunset all median field strengths are about constant.     

天波雷达电离层信道可用度统计方法研究

分析了影响天波超视距雷达(OTHR)可用度的电离层信道因素,依据一个太阳活动周期(11年)的电离层不稳定性数据,统计了中纬、中低纬和低纬地区的电离层信道可用度,OTHR频率管理系统综合考虑了电离层的基本特性以及高频干扰频谱分布特性,首次提出了基于频率管理系统工作频率表数据的电离层信道可用度的短期统计方法,并对太阳活动低年特定月份典型时刻(日出、日落、正午和夜间)的电离层信道可用度进行了统计分析.     

2020年6月21日日环食电离层Es响应研究

为研究日环食期间电离层Es演化过程,利用VHF相干散射雷达和便携式垂测仪在2020年6月21日日环食期间开展联合观测试验,得到日环食期间h′Es和f_oEs均呈现出先降低再增强的变化形态.分析表明,该演化过程类似于快速日出日落对电离层Es的影响,其成因是日环食期间太阳活动作为辐射源经历了快速减弱、复原的一个过程.本次试验观测结果对研究和完善电离层Es形成机制、机理有重要意义.     

一种考虑春秋分不对称性的电离层闪烁发生概率季节变化模型

通过分析2010年至2017年期间的中国低纬地区海口站（20°N，110°E）特高频（ultra high frequency，UHF）电离层闪烁，发现绝大部分年份中春分前后电离层闪烁事件发生概率高于秋分前后，综合电离层垂测观测数据，认为主要原因是春秋分背景电离层电子密度和h'F日落增强现象的不对称性.最后基于电离层闪烁月发生概率统计数据，及其与季节和太阳活动的相关性，建立了一种考虑春秋分不对称性的电离层闪烁发生概率季节变化统计模型.此模型能够较好地表征电离层闪烁发生概率的季节变化特性，具有重要应用价值.     

短波─跳天波多普勒频移和展宽的变化

本文通过对连续五年（１９８６—１９９０）短波一跳天波信号（收发相距为６７０Ｈｚ）的观测研究，给出了１０ＭＨｚ和１５ＨＨｚ信号回波的多普勒频移和展宽的年、月、日变化特性以及磁暴活动等对它们的影响，并从电离层电波传播角度探讨了这些参量变化的原因。     

A new simplified water vapor measurement using a multifrequencymicrowave radiometer with two-different-beamwidth antennas

A simplified method for the measurement of the atmospheric water vapor is presented. A multifrequency microwave radiometer having two different beamwidth antennas is used to measure solar extinction in terms of the difference temperature of the antennas and the relative intensity at each pair of different frequency points. The atmospheric emission component and the effect of solar fluctuation are removed automatically. Cloud absorption can be estimated by simultaneous measurement at two different frequency pairs and compensated for by the water vapor absorption. Using the specific nature of the composite weighting function defined in the opacity integral, the radiometric data can be related to the integrated water vapor and the water vapor profile     

太阳活动低年(2005—2007)期间中国低纬地区电离层foF2变化特性

利用2005—2007年广州、海口和重庆三个台站的f_oF₂数据,研究了f_oF₂日变化、季节变化和f_oF₂随太阳活动的变化规律,以及空间天气事件如磁暴对f_oF₂的影响.结果发现:f_oF₂的日变化规律体现在日出前出现最小值,海口和广州两站在14:00—16:00出现最大值,重庆站在12:00—14:00出现最大值;春秋季f_oF₂均值高于夏冬季节,春季高于秋季,冬季高于夏季（重庆站不明显）;从2005年开始,临频值整体下降,与太阳黑子数呈现正的线性关系;在2005-08-24开始的磁暴期间在磁暴的主相发生f_oF₂的正向扰动,在磁暴发生的第二天f_oF₂整体呈现负向扰动.综合以上信息可知,我国低纬地区可以划分为赤道异常区和非赤道异常区,两个地区f_oF₂有所相似但仍有不同,应结合太阳活动具体分析.     

He-Ne激光对小麦DNA UV-B损伤修复的影响

研究并分析了He-Ne激光对小麦DNA UV-B损伤修复的影响和机理,以探明激光对UV-B损伤修复的影响途径及机制。结果表明,小麦对增强UV-B辐射损伤具有一定的切除修复能力,切除修复的高峰期发生在UV-B辐射后4～6h内;He-Ne激光主要通过促进小麦的切除修复途径影响小麦对 UV-B损伤的修复,在对损伤DNA的切除及DNA的修复合成两方面均有不同程度的促进作用,其切除高峰期发生在UV-B辐射后4～6h;DNA的修复合成高峰期在辐射后6～7h。     

Solar based large scale power plants: what is the best option?

There are very few published data comparing performance and cost of thermal and photovoltaic (PV) based solar power generations. With recent intense technology and business developments there is a need to establish a comparison between these two solar energy options. We have developed a simple model to compare electricity cost using these two options without any additional fuel source of hybridization. Capital along with operation and maintenance (O&M) costs and other parameters from existing large scale solar farms are used to reflect actual project costs. To compete with traditional sources of power generation, solar technologies need to provide dispatchable electric power to respond to demand during peak hours. Different solutions for energy storage are available. In spite of their high capital cost, adding energy storage is considered a better long term solution than hybrid solar systems for large scale power plants. For this reason, a comparison between the two solar options is also provided that include energy storage. Although electricity storage is more expensive than thermal storage, PV power remains a competitive option. Expenses related to O&M in solar thermal plant are about ten times higher than PV, an important factor resulting in higher energy cost. Based on data from proven commercial technologies, this study showed that PV holds a slight advantage even when energy storage is included. Copyright © 2010 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.     

基于FPGA的太阳跟踪器的设计及实现

在简要介绍地日运行规律的基础上,确定了视日运动跟踪法的计算模型及跟踪装置的机械结构。采用FPGA芯片XC3S1500为处理器,以步进电机为执行机构,采用Verilog语言设计实现了高度角-方位角太阳跟踪系统。根据系统的要求建立了计时模块、太阳高度角方位角计算模块、日出日落时间计算模块和步进电机脉冲控制模块。通过实验测试该系统能够达到预期的性能指标,对提高太阳能的利用率具有重要的现实意义。     

A study of HF field strength variation in India and its prediction

Measured field strength data pertaining to several HF broadcast transmissions monitored in India during 1987-90 has been analysed to study solar activity, local time and seasonal variations in the field-strength. Values tend to saturate at high solar activity levels when sunspot numbers are beyond 120. Variations in field strength have also been studied with varying ratios of operational frequency to maximum usable frequency (f_op/MUF) and equivalent vertical frequency of the links. Based on this study a prediction method for HF field strength has been suggested for India. Comparison of values estimated using this technique has been made with actual measured field strength values for different HF transmissions for different months. This method is to be particularly suitable for field operators     

The variability of the ionospheric total electron content and its effect on satellite microwave communications

Rotation of linearly polarized waves (Faraday rotation) passing through the ionosphere causes depolarization in frequency reuse satellite communication systems. As the ionospheric total electron content (TEC) is not constant, dynamic compensation for this effect may be required. This paper investigates the magnitude of the TEC variations, the time scales of the variability and the predictability of the excursions. Analysis of long-term TEC measurements shows that the variations are statistical with yearly and seasonal trends strongly coupled to long term solar and geophysical effects. Short-term variations are difficult to predict. Data indicate that reliable Faraday rotation estimates can be made for 99·9 per cent of the time, provided that long-term solar, seasonal and geographical factors are considered. Occasional bursts of solar activity limit the accuracy of long-term predictions.     

New method for lateral mapping of bimolecular recombination in thin‐film organic solar cells

The best organic solar cells are limited by bimolecular recombination. Tools to study these losses are available; however, they are only developed for small area (laboratory‐scale) devices and are not yet available for large area (production‐scale) devices. Here we introduce the Intermodulation Light Beam‐Induced Current (IMLBIC) technique, which allows simultaneous spatial mapping of both the amount of extracted photocurrent and the bimolecular recombination over the active area of a solar cell. We utilize the second‐order non‐linear dependence on the illumination intensity as a signature for bimolecular recombination. Using two lasers modulated with different frequencies, we record the photocurrent response at each modulation frequency and the bimolecular recombination in the second‐order intermodulation response at the sum and difference of the two frequencies. Drift‐diffusion simulations predict a unique response for different recombination mechanisms. We successfully verify our approach by studying solar cells known to have mainly bimolecular recombination and thus propose this method as a viable tool for lateral detection and characterization of the dominant recombination mechanisms in organic solar cells. We expect that IMLBIC will be an important future tool for characterization and detection of recombination losses in large area organic solar cells. Copyright © 2016 John Wiley & Sons, Ltd.     

输油泵变频节能效果分析

针对输油泵设计富裕量较大,后期开发与工艺设计存在一定差距,多数机泵存在大马拉小车,运行效率偏低的现状,安塞油田在坪桥输油首站引进变频节能装置,对两台5DY-71/5同型号输油泵实施节能效果评估。其中1#输油泵实施变频节能改造,2#输油泵采取工频运行模式,通过近7 000小时的运行对比,机泵变频改造后泵效提高9.9%,检维修频次减少30%,经济效益明显提高,为变频节能技术在安塞油田输油领域广泛推广提供了理论依据。     

一种预测低层大气折射率剖面的实用方法

提供了一种实用的低层大气折射率剖面的短时预测方法。针对一天中折射率变化最为剧烈的日出日落前后的大气折射率剖面的试验测试，使用这个方法进行了预测。它用微波折射率仪等精密空气折射率测量设备测得的时变参数推算未来２－３ｈ的低层大气折射率剖面，结果表明预测结果和实测的大气折射率剖面相吻合。     

Solar corpuscular activity and ionization density in the F2 layer of the ionosphere

It is suggested that the ionization in the F2 region of the ionosphere is composed of contributions due to electromagnetic ultraviolet and corpuscular radiations from the sun. These two components of solar energy can be represented by sunspot and geomagnetic activity. When contributions from both these components are taken into account, the monthly mean value of the averaged diurnal characteristics of f0F2 is seen to follow fairly closely the combined effect of sunspot and geomagnetic activity, and the so-called "saturation effects" in the F2 region well nigh disappear. The monthly mean value of the diurnal average of f0F2 (Σf0F2) is seen to vary according to the expression √R+100×Ci throughout the solar cycle. In this expression R and Ci represent the monthly relative sunspot number and the international character figure for geomagnetic activity respectively.     

Interconnection between Trait,Structure, and Composition of Grain Boundaries in Cu(In,Ga)Se2 Thin‐Film Solar Cells

Grain boundaries (GBs) are crucial for solar cells incorporating polycrystalline absorbers and particularly for those characterized by small grain sizes (≈2 µm). For example, random GBs in Si solar cells are found to have a detrimental effect on the cell performance being characterized by an increased recombination activity relative to grains. Yet, their role in Cu(In,Ga)Se₂ (CIGS) solar cells still remains controversial. The recent electron‐beam‐induced current (EBIC) study shows that 58% of the GBs in CIGS exhibit enhanced electrical properties considered to be benign (for the device performance). Yet, they coexist with 16% detrimental GBs (reduced electrical properties) and 27% neutral ones (no change in electrical property when compared with the bulk). In the present study, these different GBs are investigated by combining EBIC with electron backscattered diffraction and atom probe tomography techniques on identical GBs. For the first time, a successful correlation is shown (for any device) that interconnects the GB characteristics to its composition. Sufficient statistics demonstrate that the collective fluctuations of all elements at GBs determine its trait. In general, benign (detrimental) GBs are characterized by Cu depletion (enrichment) that favored the formation of donor (acceptor) defects.     

Temperature influence on performance degradation of hydrogenated amorphous silicon solar cells irradiated with protons

This paper reports temperature influence on radiation degradation of hydrogenated amorphous silicon (a‐Si : H) solar cells. Degradation behaviors of a‐Si : H solar cells irradiated with protons at 331 K are compared with that at 298 K (room temperature). Variations with time in the post‐irradiation electrical properties are also investigated. It is found that the radiation degradation of the electrical properties at 331 K is significantly smaller than that at room temperature. Also, all the electrical properties (short‐circuit current, open‐circuit voltage, output maximum, and fill factor) recover with time after irradiation even at room temperature. The characteristic time of thermal annealing of short‐circuit current is larger as the temperature is higher. These results indicate that temperature during irradiation and elapsed time from irradiation to measurement is an important parameter for radiation degradation of a‐Si : H solar cells. Therefore, these parameters should be controlled in conducting the ground radiation tests. Copyright © 2012 John Wiley & Sons, Ltd.     

Effect of antireflection coatings and coverglasses on silicon solar cell performance

The high reflectivity of the polished silicon surface of the newer N⁺/P silicon solar cells has emphasized the need for properly designed antireflection coatings to obtain improved solar cell performance. The problem is complicated by the facts that solar cells are generally tested in air, but are for their final application covered with a glass or quartz slide which is adhesive-bonded to the cell surface, and further, that solar cells operating in a nuclear particle radiation environment change their spectral response and are frequently optimized for performance at the end of design-life. Experiments have been performed to explore the antireflection characteristics of thin films of silicon monoxide which have been evaporated on the solar cell surface. The effect of the antireflection coating thickness on cell response as a function of wavelength has been determined and the improvement in cell short circuit current for Air Mass Zero space sunlight evaluated. Included in this study was the evaluation of the antireflection characteristics after the application of a coverglass with adhesive over the antireflection coating. For comparison, coverglasses were also applied to bare cells with no antireflection coating present. In all cases the various coating comparisons were based on the cell short-circuit current performance in Air Mass Zero sunlight.     

Multiscale analysis of microvascular blood flow: a multiscale entropy study of laser Doppler flowmetry time series

Processes regulating the cardiovascular system (CVS) are numerous. Each possesses several temporal scales. Their interactions lead to interdependences across multiple scales. For the CVS analysis, different multiscale studies have been proposed, mostly performed on heart rate variability signals (HRV) reflecting the central CVS; only few were dedicated to data from the peripheral CVS, such as laser Doppler flowmetry (LDF) signals. Very recently, a study implemented the first computation of multiscale entropy for LDF signals. A nonmonotonic evolution of multiscale entropy with two distinctive scales was reported, leading to a markedly different behavior from the one of HRV. Our goal herein is to confirm these results and to go forward in the investigations on origins of this behavior. For this purpose, 12 LDF signals recorded simultaneously on the two forearms of six healthy subjects are processed. This is performed before and after application of physiological scales-based filters aiming at isolating previously found frequency bands linked to physiological activities. The results obtained with signals recorded simultaneously on two different sites of each subject show a probable central origin for the nonmonotonic behavior. The filtering results lead to the suggestion that origins of the distinctive scales could be dominated by the cardiac activity.