基于无迹变换含“风光”系统无功优化研究

由于分布式电源并网的随机性,给电网无功优化引入新的问题。本文通过无迹变换近似风电场风速、光伏电站的光照强度和负荷的有功功率的概率分布,然后,搭建考虑有功损耗、电压偏移量和优化成本的多目标无功优化模型,随后,在求解模型中将迁移算子、Hooke-Jeeves模式搜索、启发式交叉策略引入到粒子群算法中,改进了粒子群算法早熟、陷于局部最优的问题。最后,本文用IEEE-33节点的配电系统验证了本文所提算法结果损失较小误差的情况下收敛时间缩短近十倍的优势以及相比传统TPSO算法优化本模型综合结果均更优的特点。

支撑我国“风光”大规模发展的关键金属稀缺性评估与循环策略模拟

为评估支撑我国“风光”大规模发展的金属稀缺程度,构建了金属稀缺度评估模型,并对大规模“风光”发展所需的12种金属开展评估,运用金属末端循环回收模型对稀缺性强的关键金属开展金属循环回收模拟。结果显示:从金属稀缺角度看,支撑“风光”大规模发展所需的6种关键金属为铜、镍、镝、碲、锌、银,且碲、铜、镍的重要性更高“;风光”大规模发展路径的不确定性影响金属供需平衡和稀缺性,“风电主导”型路径较“光伏主导”型路径将引发更大的金属累积供应压力;金属循环再生策略将在中长期发挥作用,且对镝和银的效果更显著,金属回收率绝对值提高20%~30%,将使得金属矿产累积供应压力缓解5%~16%。研究表明,我国现有金属矿产供应能力难以支撑大规模“风光”发展的设施建设需求,金属循环回收策略对缓解金属稀缺具有一定的作用,但仅凭单一策略难以系统解决金属矿产供应制约问题。建议针对金属稀缺性与供应安全挑战构建应对策略组合时,应综合考虑金属矿产差异性、能源发展路径不确定性和金属供应规律演变3方面影响。

Rapid detection and risk assessment of soil contamination at lead smelting site based on machine learning

A general prediction model for seven heavy metals was established using the heavy metal contents of 207soil samples measured by a portable X-ray fluorescence spectrometer(XRF)and six environmental factors as model correction coefficients.The eXtreme Gradient Boosting(XGBoost)model was used to fit the relationship between the content of heavy metals and environment characteristics to evaluate the soil ecological risk of the smelting site.The results demonstrated that the generalized prediction model developed for Pb,Cd,and As was highly accurate with fitted coefficients(R~2)values of 0.911,0.950,and 0.835,respectively.Topsoil presented the highest ecological risk,and there existed high potential ecological risk at some positions with different depths due to high mobility of Cd.Generally,the application of machine learning significantly increased the accuracy of pXRF measurements,and identified key environmental factors.The adapted potential ecological risk assessment emphasized the need to focus on Pb,Cd,and As in future site remediation efforts.

Analysis on flutter performance of flexible photovoltaic support based on full-order method

Taking a three-cable flexible photovoltaic(PV)support structure as the research subject,a finite element model was established.Utilizing a full-order flutter analysis method,the flutter critical wind speed and flutter frequency of the flexible PV support structure at a tilt angle of 0°were calculated.The results showed good agreement with wind tunnel test data.Further analysis examined the pretension effects in the load-bearing and stabilizing cables on the natural frequency and flutter critical wind speed of the flexible PV support structure.The research findings indicate increasing the pretension in the load-bearing cables significantly raises the natural frequencies of the first four modes.Specifically,as the pretension in the load-bearing cables increases from 22 to 102 kN,the flutter critical wind speed rises from 17.1 to 21.6 m/s.By contrast,the pretension in the stabilizing cable has a smaller effect on the natural frequency and flutter critical wind speed of the flexible PV support structure.When the pretension in the stabilizing cable increased from 22 to 102 kN,the flutter critical wind speed increased from 17.1 to 17.7 m/s.For wind-resistant design of flexible PV support structures,it is recommended to prioritize increasing the pretension in the load-bearing cables to enhance the structural flutter performance.

110元的USB空调：E-lets usb风光威风2

最近全国一直连续高温，潮热的空气让人透不过气，炎炎夏日，怎么度过用空调吗？那个不环保哦!那就用风扇吧．但是多不方便。不光笨重最主要的还要还有电源问题。那应该用什么呢？日本E-lets公司日前发布了一款USB接口供电的风光威风2．此风扇的转速达到了前所未有的8000转／秒。

污水在防治沙暴和土壤沙漠化过程中的应用

污水、土壤沙漠化、沙尘暴是当今社会的三大危害．将三者有机结合起来的污水“风光”处理法巧用我国北方干旱地区的克足自然潜能——光能和风能，廉价地处理了污水，增加了大气湿度，改善了气候环境，有效阻止了土壤沙漠化和沙尘暴的进一步发生。

污水在防治沙尘暴和土壤沙漠化过程中的应用

污水、土壤沙漠化、沙尘暴是当今社会的三大危害.能够有效消除三大危害的污水“风光”处理法,巧用我国北方干旱地区的充足自然潜能———光能和风能,廉价地处理了污水,增加了大气湿度,改善了气侯环境,有效阻止了土壤沙漠化和沙尘暴的进一步发生.

景观概念在魏晋的起源

在不同时期和不同区域,对爱的艺术表达存在极大差异。在古典艺术中,肯定古典艺术的美,但是关注更为普遍和广泛的真实,渲染出不同程度的痛感,新柏拉图主义更是强调艺术形象在何种程度上折射出灵魂的痛苦。在基督教艺术中,爱、痛感,在强烈的感性形象中保持着崇高情怀,是基督教对源自希腊文化的西方艺术传统的极大丰富。缘心感物,则是中国古代艺术和美学最重要的命题。在心与物的对流中产生意象的恍惚,这在本质上是一种以愉悦为目的的审美活动,体现出乐感气息。中西方艺术的表现性因素及其精神依据各有特色,而真正的可比之处在于谁能否跟随时代的进程转化出新的、富于生命的形式。

MEASUREMENT AND VISUALIZATION OF FLOW FIELD IN AXIAL FLOW FAN

An experimental investigation associated with the basic fluid mechanics in an axial flow fan is described in this paper. The flow field in the tip region has been studied by laser Doppler anemometer (LDA) and flow visualization technique. Some experimental data and images are interpreted to understand the complex interactions between the annulus wall boundary layer and the leakage flow. It shows that the vortex inside the blade passage is produced by the separation of annulus wall boundary layer rather than the rolling up of leakage flow.

Laser Doppler Vibrometer Without Directional Ambiguity Using Rectangular Phase Grating

The two-phase detection method for directional discrimination in laser Doppler measurements is discussed.The diffraction efficiency of a sin- gle period rectangular phase grating is analysed and a kind of back-scattered laser Doppler vibrometer without directional ambiguity using the single peri- od rectangular phase grating as the beam-combiner described.The principles of this kind of vibrometer are explained in detail,and some experimental re- sults are given.In this kind of vibrometer,the rectangular phase grating, without the zero diffracted order and even orders,is used to eliminate use- less stray light and to combine the useful signal light.Differential electronics is employed to reject signal noise.Therefore,the signal-to-noise ratio of Doppler signals and the measurement accuracy of the instrument are im- proved and the range of application is expanded.

Water electrolysis based on renewable energy for hydrogen production

As an energy storage medium,hydrogen has drawn the attention of research institutions and industry over the past decade,motivated in part by developments in renewable energy,which have led to unused surplus wind and photovoltaic power.Hydrogen production from water electrolysis is a good option to make full use of the surplus renewable energy.Among various technologies for producing hydrogen,water electrolysis using electricity from renewable power sources shows greatpromise.To investigate the prospects of water electrolysis for hydrogen production,this review compares different water electrolysis processes,i.e.,alkaline water electrolysis,proton exchange membrane water electrolysis,solid oxide water electrolysis,and alkaline anion exchange membrane water electrolysis.The ion transfer mechanisms,operating characteristics,energy consumption,and industrial products of different water electrolysis apparatus are introduced in this review.Prospects for new water electrolysis technologies are discussed.

Observation of nocturnal low-level wind shear and particulate matter in urban Beijing using a Doppler wind lidar

A field experiment of nocturnal mountain wind and corresponding particulate matter （PM） evolution under weak synoptic forcing at five sites within urban Beijing was conducted using a moving Doppler wind lidar and a fixed tower. Clear wind shear and zero-horizontal-wind zones at 40-320 m above the ground with a delay of 1.5 h were found at two sites between 20 km from north to south urban Beijing. The wind speed and height of the low-level jet at the north urban Beijing site were greater than those at the east urban Beijing site. The average horizontal distribution of low-level PM at 240 m was similar to the ground-level PM at night. The PM2.s （aerodynamic diameter ≤2.5 μm） accumulation center showed no abrupt changes with a shift in wind direction until the northerly wind jet arrived.

Peak shaving operation optimization of high proportion new energypower generation considering wind-solar complementationand source-load coupling

To optimize peaking operation when high proportion new energy accesses to power grid,evaluation indexes are proposed which simultaneously consider wind-solar complementation and source-load coupling.A typical wind-solar power output scene model based on peaking demand is established which has anti-peaking characteristic.This model uses balancing scenes and key scenes with probability distribution based on improved Latin hypercube sampling(LHS)algorithm and scene reduction technology to illustrate the influence of wind-solar on peaking demand.Based on this,a peak shaving operation optimization model of high proportion new energy power generation is established.The various operating indexes after optimization in multi-scene peaking are calculated,and the ability of power grid peaking operation is compared whth that considering wind-solar complementation and source-load coupling.Finally,a case of high proportion new energy verifies the feasibility and validity of the proposed operation strategy.

The Equilibrium Range of Wind Wave Spectra: an Explanation Based on White Noise

Laboratory experiments and field observations show that the equilibrium range of wind wave spectra presents a – 4 power law when it is scaled properly. This feature has been attributed to energy balance in spectral space by many researchers. In this paper we point out that white noise on an oscillation system can also lead to a similar inverse power law in the corresponding displacement spectrum, implying that the – 4 power law for the equilibrium range of wind wave spectra may probably only reflect the randomicity of the wind waves rather than any other dynamical processes in physical space. This explanation may shed light on the mechanism of other physical processes with spectra also showing an inverse power law, such as isotropic turbulence, internal waves, etc.

Effects of spectral nudging on the 2010 East Asia summer monsoon using WRF model

The performance of spectral nudging in an investigation of the 2010 East Asia summer monsoon was assessed using the Weather Research and Forecasting (WRF) model, forced by 1-degree NCEP Global Final Analysis (FNL). Two pairs of experiments were made, spectral nudging (SP) and non-spectral nudging (NOSP), with five members in each group. The members were distinguished by different initial times, and the analysis was based on the ensemble mean of the two simulation pairs. The SP was able to constrain error growth in large-scale circulation in upper-level, during simulation, and generate realistic regional scale patterns. The main focus was the model ability to simulate precipitation. The Tropical Rainfall Measuring Mission (TRMM) 3B42 product was used for precipitation verification. Mean precipitation magnitude was generally overestimated by WRF. Nevertheless, SP simulations suppressed overestimation relative to the NOSP experiments. Compared to TRMM, SP also improved model simulation of precipitation in spatial and temporal distributions, with the ability to reproduce movement of rainbands. However, extreme precipitation events were suppressed in the SP simulations.

Compensation/consumption hierarchical control strategy based on wind-solar-hydrogen coupling grid connection

In the process of grid-connected wind and solar power generation,there are problems of high rate of abandoning wind and light and insufficient energy.In order to solve these problems,we construct a grid-connected wind-solar hydrogen storage(alkaline electrolyzer(AE)-hydrogen storage tank-battery-proton exchange membrane fuel cell(PEMFC))coupled system architecture.A grid-connected compensation/consumption hierarchical control strategy based on wind-solar hydrogen coupling is proposed.During the grid-connected process of wind and solar power generation,the upper-level control allocates power reasonably to the hydrogen energy storage system by dispatching the power of wind and solar power generation.At the same time,the control strategy ensures that the pressure of the hydrogen storage tank is within the safety range limit,and the lower control completes the control of the duty cycle of the converter in the system.Due to the randomness of wind and light,the hydrogen energy storage system is divided into three working conditions,namely compensation,balance and consumption,and five working modes.The simulation results show that the hydrogen energy storage system compensates for 40%of the power shortage,and consumes 27.5%of the abandoned wind and solar energy,which improves the utilization rate of clean energy.

^(15)N NMR Spectroscopic Study on Nitrogen Forms in Humic Substances of Soils

Nitrogen forms of humic substances from a subalpine meadow soil, a latentic red soil and a weathered coal and the effect of acid hydrolysis on N structures of soil humic substances were studied by using 15N cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy. Of the detectable 15N-signal intensity in the spectra of soil humic substances 71%-79% may be attributed to amide groups, 10%-18% to aromatic/aliphatic amines and 6%~11% to indole- and pyrrole-like N. Whereas in the spectrum of the fulvic acid from weathered coal 46%, at least, of the total 15N-signal intensity might be assigned to pyrrole-like N, 14% to aromatic/aliphatic ammes, and the remaining intensities could not be assigned with certainty. Data on nonhydrolyzable residue of protein-sugar mixture and a 15N-labelled soil fulvic acid confirm the formation of nonhydrolyzable heterocyclic N during acid hydrolysis. Project (No. 39790100) supported by the National Natural Science Foundation of China.

Labor Market Aspects of the ＂New Rurality＂： Employment, Commuting and Entrepreneurship in Rural Sweden

Around two thirds of the Swedish rural areas experienced positive net migration during the period 2003-2005. This paper examines the development in the Swedish rural areas from the perspective of the ＂new rurality＂ or the new rural economic order with regard to migratory movements. The paper analyzes determinants of net migration to rural areas in general and to different types of regions, and the impacts of in-migration on rural labor markets, self-employment and other socio-economic conditions. The determinants of the migration pattern were mainly the size of adjacent local and regional centers, income and education levels that all had positive impacts, while commuting distance and unemployment rate had contrary effects. In comparison with the original inhabitants, the newcomers had lower incomes, a lower employment ratio and a lower degree of entrepreneurial activities, but higher education levels. These differences might be explained by the age differences between stayers （older） and in-migrants （younger）. This indicates that the two groups were in different stages of their life cycles. One central conclusion drawn from the paper is that the effect of in-migration on the composition of the rural population is about the same in rural areas all over Sweden.

Directional Spectrum of Wind Waves: Part Ⅱ- Comparison and Confirmation

A model on the directional frequency spectrum of wind waves for deep water is introduced. The comparisons of the proposed model with other existing models show that the proposed model is very close to the JONSWAP model and DHH model for describing the developing waves under the normal spectral bandwidth, and has a better description for the transition of the unidirectional spectrum from ω -4 to ω -5 at a position around 3ω p, i.e., three time the peak frequency. Comparisons also show that the proposed model describes closely both field data measured by a four-frequency radar and a laser-optical sensor, and laboratory data measured by a laser slope gauge and an imaging optical method. The comparisons further demonstrate that the inverse spectral bandwidth as a new wave parameter is robust for describing the spectral steepness. Finally, the formula on the local spectral-peak angular frequency is confirmed using the observed two-dimensional spectra.

Determination of Astragaloside IV in Yupingfeng Oral Solution by HPLC-ELSD Method

[Objective] This study aimed to establish a method for determining the content of Astragaloside IV in Yupingfeng oral solution.[Method] The HPLC-ELSD method was adopted.The chromatographic column was Venusil MP（4.6 mm × 150 mm,5 μm）.The mobile phase was acetonitrile-water（35∶65）.The ELSD evaporator tube temperature was 65 ℃.N2 was used as the carrier gas（pressure,30 psi）.[Result] When the content of Astragaloside IV ranged from 0.5 to 5.0 μg,the Astragaloside IV content showed a good linear relationship with peak area（r=0.999,n=6）.The average recovery was 96.36%,and the RSD was 2.46%.[Conclusion] This method is accurate and reliable,and can be applied in the quality control of Yupingfeng oral solution.