Effect of Hole Configuration on Heat Transfer through a Hollow Block Subjected to Solar Flux

In this paper,some effort is provided to optimize the geometry of a concrete hollow brick(used in the construction of building roofs)in order to increase the related thermal resistance,thereby reducing energy consumption.The analysis is conducted for three different configurations of the hollow concrete bricks.Coupling of conduction,natural convection and thermal radiation phenomena is considered.Moreover,the flows are assumed to be laminar and two-dimensional for the whole range of parameters examined.The conservation equations are solved by a finite difference method based on the control volumes approach and the SIMPLE algorithm for velocity-pressure coupling.The results show that the aspect ratio affects neither the nature of the fluid flow nor the number of convective cells.However,the extension of the circulation cells increases with this parameter.Moreover,the cavities with a large aspect ratio lead to significant reductions in the heat transfer through the hollow block,these reductions reaching approximately 14%.

Inverse Correlations between Daily Average Energy of Global 0.01 to 1 M Earthquakes and Solar Flux Units: Possible Source of Coupling

The potential coupling between discrete releases of solar energy within the 2.8 GHz band and increments of seismic energy could suggest alternative mechanisms for solar-terrestrial interactions. Daily measures of Solar Flux Units (SFU) and the average energy of global earthquakes between 0.01 and 1 M for a 5 year period (2009-2013) shared about 25% of the same variance (r = -0.50). Average energies from the other successive 1 M intervals did not display the strength of this effect or were not statistically significant. The slope of the association indicated that for every 10-22 W/m2Hz1 decrease in daily SFUs, the average energy per earthquake in the 0.01 to 1 M range increased over the earth’s surface area on average by ~3 × 10-12 J/m2. The discrepancy of ~1010 in energy density was accommodated by multiplication of the solar unit by the frequency equivalent (1.39 × 1010 Hz/T) of the Bohr magneton and its intrinsic magnetic field strength. Although the results and the convergent quantification suggest a coupling between the mechanisms responsible for fluctuations in 2.8 GHz power from the sun and the energies of the smallest magnitude earthquake activities as predicted, the presence of a third factor related to time or to the sun’s movement through space must still be accommodated.

A design method and numerical study for a new type parabolic trough solar collector with uniform solar flux distribution

The non-uniform concentrated solar flux distribution on the outer surface of the absorber tube can lead to large circumferential temperature difference and high local temperature of the absorber tube wall,which is one of the primary causes of parabolic trough solar receiver(PTR)failures.In this paper,a secondary reflector used as a homogenizing reflector(HR)in a conventional parabolic trough solar collector(PTSC)was recommended to homogenize the solar flux distribution and thus increase the reliability of the PTR.The design method of this new type PTSC with a HR was also proposed.Meanwhile,the concentrated solar flux distribution was calculated by adopting the Monte Carlo ray-trace(MCRT)method.Then,the coupled heat transfer process within the PTR was simulated by treating the solar flux calculated by the MCRT method as the heat flux boundary condition for the finite volume method model.The solar flux distribution on the outer surface of the absorber tube,the temperature field of the absorber tube wall,and the collector efficiency were analyzed in detail.It was revealed that the absorber tube could almost be heated uniformly in the PTSC with a HR.As a result,the circumferential temperature difference and the maximum temperature could be reduced significantly,while the efficiency tended to decrease slightly due to the inevitably increased optical loss.Under the conditions studied in this paper,although the collector efficiency decreased by about 4%,the circumferential temperature difference was reduced from about 25 to 3 K and the maximum temperature was reduced from667 to 661 K.

Influence of solar wind energy flux on the interannual variability of ENSO in the subsequent year

作为地球系统的主要能量来源,进入地磁系统的太阳风能量通量(E_(in))一直难以估算。因此,E_(in)对气候的影响也没有得到广泛的研究。基于三维磁流体动力模拟估算的E_(in),本文指出,太阳风能量通量不仅存在准11年周期的年代际变率,同时还存在2-4年周期的年际变率。与以往主要关注太阳活动在年代际尺度上的气候效应的研究不同,本文揭示出太阳风能量通量与次年ENSO年际变率存在显著的联系。

Theoretical Analysis of Retrieving Atmospheric Columnar Mie Optical Depth from Downward Total Solar Radiative Flux

In this paper, the principle to determine the atmospheric columnar Mie optical depth from downward total solar radiative flux is theoretically studied, and the effect on Mie optical depth solution of the errors in surface albedo, sin-gle scattering albedo, asymmetrical factor of scattering phase function, instrumental constant and the approximate expression of diffusion flux is analy/ed, and then a method for determining surface albedo in shorter wavelength range is presented.

Model of Spectral Fluxes for Solar Spectrograph

Taking use of the solar spectrograph in Yunnan Observatory, we built a model to estimate the spectral fluxes of solar spectrograph with computer and confirmed the result by observations. The spectral fluxes in visible and near infrared bands were calculated for the solar spectrograph of Yunnan Observatory.

新型槽式太阳能真空吸热管设计方法及其光学性能研究

针对传统槽式太阳能集热系统工质运行温度受限,以及真空吸热管表面能流密度分布不均而引起的热应力过大等问题,文章在不改变聚光器结构的条件下,提出了一种新型的槽式太阳能真空吸热管的设计方法,通过减小金属内管直径、下移金属内管位置以及在金属内管上方加装双曲线型二次聚光器来提高太阳能聚光比,改善了金属吸热管表面能流密度分布。利用仿真计算方法研究了新型槽式太阳能真空吸热管的光学性能,结果表明:和传统槽式太阳能真空吸热管相比,该新型结构在仅损失1.88%光学效率的情况下将聚光比从62 kW/m^(2)提升至71 kW/m^(2);能流密度分布均匀度改善了55.05%,提升了聚光-吸热系统的整体性能。

基于热电效应高倍聚光焦面能流密度测量研究

焦面能流密度分布是评价太阳能聚光器聚光效果的关键因素,对聚光太阳能电池或热发电接收器的设计、安装和传热分析等起到了决定性作用。利用铠装热电偶高温测量的优势,提出基于热电效应原理的能流密度分布间接测量方法。通过ANSYS软件构建铠装热电偶的传热模型,将聚光太阳能能流作为输入,对其稳态传热过程进行分析,得到能流密度与输出温度之间的热力学函数,利用此函数的反函数开展高倍太阳能聚光焦面能流密度的测量。研究了风速和环境温度对模型的影响。结果表明:风速对该函数关系影响较大,环境温度影响很小。采用菲涅尔透镜搭建实验系统,对模型进行了验证,能流密度大于600 kW/m^(2)时,实测数据与模型的相对误差在5%以内,模型的准确度较好。

Relationship between Solar Activity, Total Ozone, and Solar Ultraviolet Radiation: Multifractal Analysis

We investigated the relationship between solar activity, total ozone, and solar ultraviolet B (UV-B) radiation from the perspective of multi-fractality. Fractal properties are observed in the time series of the dynamics of complex systems. To detect the changes in fractality, we performed a multifractal analysis using a wavelet transform. The changes in fractality indicated that solar activity was closely related to the total ozone and that the total ozone had a strong effect on UV-B radiation. For high solar activity, the F10.7 flux and global total ozone exhibited monofractality. The F10.7 flux and total ozone also increased, and a change from multifractality to monofractality was observed. This corresponded to the formation of the order. The strong interactions between the solar flux and ozone occur during the high solar activity. In contrast, UV-B radiation increased and showed multifractality, when fluctuations in UV-B radiation became large. For low solar activity, the F10.7 flux and total ozone exhibited multifractality, and UV-B radiation exhibited monofractality. Hence, the change in fractality of the F10.7 flux and total ozone was the opposite of UV-B radiation. A significant change in fractality for F10.7 flux and SSN, which had a significant fluctuation and a slight change in fractality for UV-B radiation, and total ozone were identified.

Study Optimization of a Hybrid Solar-Wind System from an Individual in Ouagadougou

This work is a contribution to the study of hybrid systems for converting solar and wind energy into electricity in Burkina Faso. The approach consists of evaluating and analyzing the production of a wind turbine and a solar field in order to optimize the production of all the technologies. The results obtained made it possible to evaluate the operating performance of the installation and to show the complementarity between the two energy sources with regard to temporary and seasonal variations in resources. During nighttime periods or periods of low sunlight, the wind turbine is a good alternative to energy storage by batteries, the output of the wind turbine can be up to 853.76 W. It was also a question of proposing solutions for optimizing the hybrid system through the automation of the hybrid charge regulator. A minimum height of 30 m above the ground has been chosen as the optimum height for the wind turbine.

The Relation among the Solar Activity, the Total Ozone, QBO, NAO, and ENSO by Wavelet-Based Multifractal Analysis

There is an increasing interest in the relation between the solar activity and climate change. As for the solar activity, a fractal property of the sunspot number was studied by many works. In general, a fractal property was observed in the time series of dynamics of complex systems. The purposes of this study are to investigate the relations among the solar activity, total ozone, Quasi-Biennial Oscillation (QBO), the North Atlantic Oscillation (NAO), and El Ni?o-Southern Oscillation (ENSO) from a view of multi-fractality. To detect the changes of multifractality, we examined the multifractal analysis on the time series of the solar 10.7-cm radio flux (F10.7 flux), total ozone, QBO, NAO, and Ni?o3.4 indices. During the period 1950 and 2010, for the F10.7 flux and QBO index, the matching in monofractality or multifractality is observed and the increase and decrease of multifractality is similar;that is the change of multifractality is similar. In the same way, it is very similar, during the period 1985 and 2010, for the QBO and the total ozone, and during the period 1950 and 2010, for the QBO, and NAO and for the QBO, and Ni?o3.4. Compared to Ni?o3.4, the multifractality of NAO and QBO was strong and it turns out that they are undergoing unstable change. The relation among the solar activity, total ozone, QBO, NAO, and ENSO was clarified by the methods of fractal analysis and the wavelet coherence. These findings will contribute to the research of the relation between the solar activity and climate change.

Solar Influences on the North Atlantic Oscillation by Wavelet-Based Multifractal Analysis

There is increasing interest in the relation between the solar activity and climate change. Regarding the solar activity, the fractal property of the sunspot number (SSN) has been studied by many previous works. In general, fractal properties have been observed in the time series of the dynamics of complex systems. The purpose of this research is to investigate the relationship between the solar activity, total ozone, and the North Atlantic Oscillation (NAO) from a viewpoint of multi-fractality. To detect the changes of multifractality, we performed the wavelets analysis, and plotted the τ-function derived from the wavelets of these time series. We showed that the solar activity relate to the NAO, by observing the matching in monofractality or multifractality of these indices. When the SSN increased and the solar activity was stable, the NAO also became stable. When the SSN became maximum, the fractality of the SSN, F10.7 flux, geomagnetic aa, and NAO indices changed from multifractality to monofractality and those states became stable for most of the solar cycles. When the SSN became maximum, the fluctuations became large and multifractality became strong, and a change from multifractal to monofractal behavior was observed in the SSN, F10.7 flux, geomagnetic aa, and NAO indices. The strong interactions of the solar flux, geomagnetic activity, total ozone, and NAO occur in the SSN maximum. The strong interactions were inferred from the similarity of fractality changes and the wavelet coherence. The influence of the solar activity on the NAO was shown from a viewpoint of multi-fractality. These findings will contribute to the research on the effects of the solar activity on climate change.

The Particular Lines in the Solar Neutrino Energy Spectrum

In this paper, much attention is given to lines of minimum and maximum neutrino energies. Tritium chain of the hydrogen cycle in the Sun including reactions of 3He(e-,νe)3H(p,γ)4 is considered. At the distance of 1 a.u., the flux of tritium neutrinos is equal to 8.1 × 104 cm-2·s-1. It is an order of magnitude higher than the flux of the (hep)-neutrinos. Radial distribution of 3H-neutrinos yield inside the Sun and their energy spectrum which has a form of line at the energy of (2.5 - 3.0) keV are calculated. The flux of thermal tritium neutrinos is accompanied by a very weak flux of antineutrinos (~103 cm-2·year-1) with energy lower than 18.6 keV. These antineutrinos are produced during Urca processes 3He3H. The flux of the neutrinos of maximum possible energy (line 19.8 MeV) produced due to the (heep)-reaction (related to the (hep)-process) is estimated.

Analysis of water vapour flux between alpine wetlands underlying surface and atmosphere in the source region of the Yellow River

An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how environmental factors influence latent heat flux have considerable scientific significance. Using data from observational tests of the Maduo Observatory of Climate and Environment of the Northwest Institute of Eco-Environment and Resource, CAS, from June 1 to August 31, 2014, this study analysed the time-varying characteristics and causes of the degree of coupling(Ω factor)between alpine wetlands underlying surface and the atmosphere and quantitatively calculated the influences of different environmental factors(solar radiation and vapour pressure deficit) on latent heat flux. The results were as follows:(1) Due to diurnal variations of solar radiation and wind speed, a trend developed where diurnal variations of the Ω factor were small in the morning and large in the evening. Due to the vegetation growing cycle, seasonal variations of the Ω factor present a reverse "U" trend. These trends are similar to the diurnal and seasonal variations of the absolute control exercised by solar radiation over latent heat flux. This conforms to the Omega Theory.(2) The values for average absolute atmospheric factor(surface factor or total) control exercised by solar radiation and water vapour pressure are 0.20(0.02 or 0.22) and 0.005(-0.07 or-0.06) W/(m2·Pa), respectively. Generally speaking, solar radiation and water vapour pressure deficit exert opposite forces on latent heat flux.(3) At the underlying alpine wetland surface, solar radiation primarily influences latent heat flux through its direct effects(atmospheric factor controls). Water vapour pressure deficit primarily influences latent heat flux through its indirect effects(surface factor controls) on changing the surface resistance.(4) The average Ω factor in the underlying alpine wetland surface is high during the vegetation growing season, with a value of 0.38, and the degree of coupling between alpine wetland surface and atmosphere system is low. The actual measurements agree with the Omega Theory. The latent heat flux is mainly influenced by solar radiation.

Parameterized Transmittance Model for Atmospheric and Surface Solar Radiations

This work describes a transmittance model that evaluates global solar irradiation through the atmospheric column and at surface. The model is based on appropriate determination of the transmission coefficients of the different atmospheric constituents in a plane parallel layers frame and estimates the downward solar fluxes from the upper limit of the atmosphere. In testing this model, we first considered the purely molecular atmosphere to parameterize descending solar fluxes, which allowed us to estimate the attenuation due to atmospheric gases at specific times of the day when the irradiation at ground level is known. The results thus obtained show that the molecular atmosphere has a maximum reduction rate of incident flux (at the Top Of Atmosphere) of 20% with daily profiles that are homogeneous with extraterrestrial fluxes. Considering the turbid and cloudy atmosphere in which the multiple scattering phenomenon is taken into account, we obtain at ground level fluctuating profiles with attenuation rates reaching 64% depending on the time instant in the day. The comparison of our results with the experimental data obtained at the Yaoundé site on one hand and with the results of the CLIRAD-SW model on the other hand shows at monthly scale high correlation, of the order of 0.998. Moreover at monthly time scale, the precision which for some hourly values is relatively low tends towards a net improvement on the seasonal scale where it extends over a narrow domain ranging from 0.02% to 1.66%.

Solar Activity during the Rising Phase of Solar Cycle 24

Solar activity refers to any natural phenomenon occurring on the sun such as sunspots, solar flare and coronal mass ejection etc. Such phenomena have their roots deep inside the sun, where the dynamo mechanism operates and fluid motions occur in a turbulent way. It is mainly driven by the variability of the sun’s magnetic field. The present paper studies the relation between various solar features during January 2009 to December 2011. A good correlation between various parameters indicates similar origin.

基于气候变化的线性菲涅尔聚光系统能流密度分布规律

文章针对小型线性菲涅尔聚光系统设计了一套能流密度测试装置,研究了呼和浩特地区风沙大和纬度高等特点下系统能流密度的变化。结果表明:线性菲涅尔聚光系统的能流密度存在明显的季节性差异,夏季在11:00-15:00焦平面的平均能流密度较高,而春季和秋季在9:00-10:00和15:00-16:00焦平面上能流密度较高,冬季9:00-10:00的平均能流密度较高,夏季焦平面上的平均能流密度比冬季高2.27 kW/m^(2)。反射镜表面连续积尘54 d后,焦平面上的能流密度下降了62.7%,以镜面积尘密度作为量化指标发现,镜面积尘密度每增加1 g/m^(2),焦平面上的平均能流密度就会下降0.63 kW/m^(2)。该研究可为小型线性菲涅尔聚光系统在干旱高纬度地区运行维护提供数据参考。

海口中层大气温度变化特性的Rayleigh激光雷达观测研究

中层大气温度变化的探测与研究是当前气候变化研究课题的一个组成部分,本文基于海南激光雷达2010—2020年间的长期观测,通过对中层大气Rayleigh散射信号的反演,探讨了海口(19.9°N,110.3°E)上空中层大气(32~64 km)温度变化特性.研究结果显示,中层大气温度呈周期性变化趋势,年、半年、季节变化幅度最大值分别为6.0、3.8、1.7 K,平流层顶位于42~51 km高度,日平均温度最高为~262 K.平流层温度主要表现为年变化趋势,半年和季节变化不明显;平流层顶和低中间层温度变化趋势具有年和半年变化特征,季节变化不明显.在太阳活动性发生明显变化的周期里,平流层顶温度的年际变化趋势对辐射通量F10.7指数变化有较明显的响应;而在太阳活动平静的年份里,温度变化趋势与太阳辐射通量变化的相关性不明显.

Preliminary Results of Solar Flare Induced D-Region Perturbations over UKM Using Stanford AWESOME Receiver

We present the preliminary results of VLF signal perturbations produced due to solar flare. The data were recorded by the Stanford VLF AWESOME receiver located at National University of Ma-laysia, Selangor. Two new long distance (>1000 km) VLF paths, JJI-UKM (2700 km) and NWC-UKM (3300 km) were analyzed simultaneously. Data from the GOES satellite were used to determine the onset time and type of each of these flares. Results indicated that all five solar flare events with an X-ray peak flux above 10-5 W/m2 (M-class) were recorded, 37.5% for X-ray flux greater than 10-6 W/m2 (C-class), while the weakest X-ray flux recorded was 2.6 × 10-7 W/m2 (B-class) with 0.24% probing potentiality. We found a strong positive correlation (0.84) between solar flare radiation intensity and the values of amplitude and phase perturbations for both paths. The values of amplitude and phase perturbations time-correlated with solar flare, varied from 0.2 to 5 dB and 0.15 to 20 degree respectively. These findings are in complete agreement with previous works and demonstrate that the data obtained by the UKM AWESOME observation station will provide addi-tional contribution to the study of ELF/VLF waves phenomena in the ionosphere/magnetosphere, especially at low latitudes region.