A model for all seasons

This paper presents the integration of dynamic security assessment with real-time energy management.     

Union building for you all [History]

This paper presents the history of a professional society, American Institute of Electrical Engineers (AIEE). The institute was formed for the purpose of having a representative at International Electrical Exhibition. This article is a companion piece to the author's article on the Brokaw Mansion, the home of the Institute of Radio Engineers (IRE) before the 1963 merger. This article is an expanded version of an article that first appeared in the October 2006 issue of the Proceeding of the IEEE     

Power blackouts a wake up call for all

The recent power outage in the northeastern region of the US and Canada is a “wake-up call to decision makers,” says the Rocky Mountain Institute (www.rmi.org), and called for distributed, diverse and resilient clean technologies to power their economy. The existing system is based on a century of heavily-centralized generation and distribution policies, “can trigger a cascading series of errors that leaves us vulnerable and should be corrected.”This is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news.     

Analysis of zenith luminance data for all sky conditions

Two different procedures are explored in the present work to estimate the zenith luminance at the International Daylight Measurement Program station in Madrid, when all the data available are used independently of the sky type. On the basis of the results obtained, correlations for the seasonal dependence of the zenith luminance on solar elevation are reported. However, it is observed that polynomials obtained for different ranges of the luminous clearness index, the ratio of global to extraterrestrial illuminance, can predict the zenith luminance with a more reasonable accuracy. The results show that the luminous clearness index is an important parameter for zenith luminance characterization, to be used when global illuminance values on horizontal surfaces are available, but diffuse illuminance is not measured     

Global luminous efficacies on vertical surfaces for all sky types

Luminous efficacies are determined at Madrid for North, South, East, West facing surfaces in two ways: by taking into account all the global illuminance and irradiance values available, and by considering data for each of three sky categories as defined from values of the sky clearness index ′ and the sky brighteness index Δ. Both methods are compared, and for ′<1.23 (overcast skies) the second method is found to be more accuarate than the first.     

Electrode materials for all vanadium flow batteries:A review

电极材料在钒电池发展及应用中起到了至关重要的作用,对于钒电池电极的研究既包括不同基体电极材料的筛选,制备,也包括电极材料的结构优化,表面改性及模拟等.本文首先简要介绍了钒电池用电极材料的分类及其相关代表性结果,明确了电极材料的发展方向,其中具有耐腐蚀性,高电导率,高比表面积,高活性及价格低廉的电极材料成为研究的重点.随后以最具有实用价值的炭素电极材料为中心,详细介绍了该类材料的研究进展以及当前研究过程中存在的问题及可能的解决途径.最后,对电极材料的下一步研究工作进行了展望,认为不仅在电极材料产业化方面需要有进一步的突破,在与电极相关的基础研究如电极过程动力学等方面也需要有更为深入的探讨.     

Luminous efficacy of direct solar radiation for all sky types

Three models for the luminous efficacy of direct solar radiation on a horizontal surface, valid for all sky conditions, have been developed in the present work, and two of them are proposed. In all the models a function for the direct luminous efficacy for all sky conditions relative to the direct luminous efficacy for clear skies is obtained, using the function for the direct luminous efficacy for clear skies given in a previous work, and the brightness index as a new independent variable. One of the two models is obtained by fitting the values of the relative luminous efficacy as a function of the brightness index. The other proposed model is developed by obtaining in the first place models for direct illuminance and direct irradiance, both relative to the corresponding clear sky models, and then finding the ratio between the relative direct illuminance and irradiance models. Statistical assessment of the direct illuminance values estimated with the proposed models gives similar values for the MBE and the RMSE. However, the model obtained from illuminance and irradiance models is mathematically coherent.     

Calculations and measurements of the Unity Plus three-phaseinduction motor

The Unity Plus induction motor configuration for three-phase motors is described and analyzed. In the Unity Plus winding method only one set of windings, called the power winding, is connected directly to the source. The second set of windings is connected to capacitors and is coupled to the power winding through transformer action. The equivalent circuit of the Unity Plus motor for steady-state operation is obtained through standard induction motor analysis methods. Laboratory experiments on a 10 hp three-phase induction motor, both as a conventional winding configuration and as a Unity Plus configuration after rewinding by Unity Plus representatives, verified the accuracy of the circuit model and showed that the Unity Plus winding configuration did not result in higher efficiencies than that obtainable from conventional winding methods     

Energy for all: Obstacles and success conditions for RE in developing countries

In many developing countries there is a much larger potential for renewables like wind and solar energy than in industrialised countries. But there are obstacles that prevent the adoption of such “new” renewables in developing countries. Ulrich Laumanns and Danyel Reiche try to identify the most important obstacles and point to success conditions that can lead to a wider dissemination of “new” renewables in developing countries.     

GPS监测网变形分析基础的统一及稳定性分析

在对GPS监测网的观测成果进行平差计算和变形分析时,必须考虑GPS网的位置基准、尺度基准和方位基准统一的问题。叙述了无穷权在变形监测网基准统一中的应用,分析了GPS监测网的稳定性。     

135 MWe CFB锅炉各级过热器焓增试验研究

主要针对上海锅炉厂有限公司在引进、吸收美国ALSTOM公司循环流化床锅炉技术方面对设计、制造、投运的首批135 MWe级CFB锅炉在启动低负荷阶段易出现冷、热屏和悬吊管超温问题,通过在实炉对各级过热器进行了焓增试验,进而更了解CFB锅炉的传热特性及各段过热器受热面的吸热量分配状况以及运行方式对其影响,为查找和解决问题及完善热力计算提供修正依据.     

Towards a predictive evaporation model for multi-component hydrocarbon droplets at all pressure conditions

In this paper, a new evaporation model for multi-component hydrocarbon droplets is proposed. Compared to previously published models, it has two new features. First, an expression of the Stefan velocity is proposed which ensures gas mass conservation. In addition, the evaporation rate of each species is obtained by the integration of the exact equation of species mass fraction. Second, the heat flux due to species diffusion is taken into account in addition to the classical conduction heat flux between the gas and the liquid droplets. The comprehensive multi-component droplets vaporization model including the above two features is presented for high and low pressure conditions, for which a real and a perfect fluid equation of state (EOS) has been used, respectively. Free convection is also taken into account using the Grashof number in the Kulmala–Vesala correlations [1] for the Sherwood and Nusselt numbers. The model is compared with very accurate experimental data which were recently obtained by Chauveau et al. (2008) [2] at atmospheric pressure and temperature ranges of 473–973 K for n-heptane and 548–623 K for n-decane droplets of 400 μm initial size. A very good agreement with the experimental data including micro-gravity conditions has been obtained. Indeed, the results have confirmed that the free convection process plays a significant role in the evaporation rate of liquid droplets under earth gravity and quiescent conditions. This shows the relevance of the new features of the model. The numerical results have also shown that real fluid EOS is not necessary at atmospheric pressure for the temperature range given above. In addition, the numerical results of the new model are also compared with the experimental data of Birouk (1996) [3] for two-component droplets of n-heptane and n-decane with different compositions of the liquid mixture. Finally, the non-ideality of the mixture is shown to become significant at high ambient pressures and especially at low ambient temperature conditions where a real-gas EOS is needed.     

Ultra-small RuPx nanoparticles on graphene supported schiff-based networks for all pH hydrogen evolution

As a promising candidate to replace Pt in hydrogen evolution reaction (HER), ruthenium phosphide catalysts have shown excellent performance and attract increasing attention. However, it is still a challenge to control the particle sizes of RuP_x were on the supports. In this study, the Schiff-based networks with 3D rigid organic networks are successfully grown on graphene, and the obtained composite was used as a new support for the RuP_x. This composite can not only provide more metal coordinating sites but also restrict the growth of RuP_x. Therefore, ultra-small RuP_x nanoparticles are uniformly dispersed via a subsequent phosphating and pyrolysis process. The final RuP_x/NPG catalyst exhibits low overpotentials at the current density of 10 mA cm⁻² (32 mV in 0.5 M H₂SO₄ solution, 13 mV in 1 M KOH solution, and 50 mV in 1 M PBS solution). This work provides a new strategy to solve the aggregation problem of the metal phosphides on the substrate by introducing Schiff-based networks into the graphene.     

也谈全天候太阳能热水系统

何谓“全天候太阳能热水系统”，简单的说就是一年365天、每天24小时，时时都有热水备用的太阳能热水系统及工程。让用户(包括集体用户和家庭用户)再也不用为“现在洗浴有热水吗”而操心。它比过去使用过的“天天有热水”，实际上是天天的某个时段才有热水的承诺有更加明确的概念界限。也让用户遇到阴雨风雪等恶劣天气环境时无后顾之忧。     

Delivering accurate and timely data to all

This paper discusses a model-based substation automation application for advanced data availability. The SuperCalibrator concept provides a basic technology to filter all substation data that are readily available by the substation automation scheme. The SuperCalibrator is conceptually very simple. It is a state estimator using a detailed three-phase breaker-oriented instrumentation-inclusive substation model. As such, the errors introduced by the instrumentation are compensated and the estimated values are closer to the actual values of the electric power system. The overall methodology identifies bad data and wrong topologies and quantifies the quality of the filtered data expressed in terms of the expected error in this data. Substation automation enables the seamless implementation of the SuperCalibrator. In turn, the SuperCalibrator substantially contributes toward the promise of substation automation to reliably provide accurate data to all clients. The applications discussed in this article should ignite the dialog and the realization that substation automation can make it possible to dramatically improve our approaches and tools in monitoring, controlling, and protecting the electric power grid infrastructure     

A generalized method for testing all classes of solar collector—I attainable accuracy

Part I, of this three part paper, sets out what accuracy can be obtained for a thermal performance test of a solar collector under a range of operating conditions. It also highlights where improvements have to be made in order to improve the currently attainable accuracy.     

Self-regulating passive fuel supply for small direct methanol fuel cells operating in all orientations

A microfluidic fuel supply concept for passive and portable direct methanol fuel cells (DMFCs) that operates in all spatial orientations is presented. The concept has been proven by fabricating and testing a passive DMFC prototype. Methanol transport at the anode is propelled by the surface energy of deformed carbon dioxide bubbles, generated as a reaction product during DMFC operation. The experimental study reveals that in any orientation, the proposed pumping mechanism transports at least 3.5 times more methanol to the reactive area of the DMFC than the stoichiometry of the methanol oxidation would require to sustain DMFC operation. Additionally, the flow rates closely follow the applied electric load; hence the pumping mechanism is self-regulating. Oxygen is supplied to the cathode by diffusion and the reaction product water is transported out of the fuel cell along a continuous capillary pressure gradient. Results are presented that demonstrate the continuous passive operation for more than 40 h at ambient temperature with a power output of p = 4 mW cm⁻² in the preferred vertical orientation and of p = 3.2 mW cm⁻² in the least favorable horizontal orientation with the anode facing downwards.