Capacitive characteristics and electrosorption of hydrogen in microporous aсtivated carbon fibers

The possibility of hydrogen electrosorption in microporous activated carbons for acidic and alkaline electrolytes is shown. The electrochemical behavior of activated carbon fiber CH-900-20 has been investigated to find out the main factors, which influence the charging processes of microporous electrodes. The following methods were used: cyclic voltammetry, electrochemical impedance spectroscopy, chronoamperometry, and chronopotentiometry. A comparative analysis of the influence of the electrolyte type and electrode structure on the capacitance performances of carbon has been carried out. It is assumed that there is a potential barrier at the interface between micropores and macropores. The features of the process of hydrogen electrosorption in carbon micropores have been analyzed in detail. A possible mechanism of electrosorption in micropores that decreases the capacitance of the electric double layer with a corresponding drop of the electronic conductance of activated carbons in acidic electrolytes has been suggested. The influence of temperature on the kinetics of hydrogen electrosorption has been shown and the activation energy of this process has been estimated. An assumption has been made about the influence of the semiconductor conductivity of activated carbons on the capacitive and resistive characteristics of the electrodes.     

Integration of Demand Response in Electricity Market Capacity Mechanisms

Ensuring that the power system meets demand peaks is a key challenge of liberalized markets. On the supply side, capacity can be supported through a Capacity Remuneration Mechanism (CRM). On the demand side, Demand Response (DR) technologies can be deployed. We find that while all traditional generation should receive the same payment, capacity payments for DR technologies should gradually decrease based on operators’ position in the load-shedding order. We observe that all CRM schemes currently implemented provide inadequate incentives to non-price responsive DR and propose to adjust payments to DR units as a function of their expected activation periods.     

Product mix determination and capacity allocation for heterogeneous products in thin film transistor liquid crystal display manufacturing

In the thin-film transistor liquid crystal display (TFT-LCD) manufacturing, the development of models to determine product mix and capacity allocation for a multi-stage, multi-site, and multi-generation company is very important. As rapid advancement of the electronic-paper display (EPD) technology, it is a trend of the coexistence of heterogeneous products involving LCD and EPD products. In the case we investigated, the TFT-LCD company merged an EPD company and incorporated their electro-phoretic technologies into their company. Notably, the manufacturing processes of the EPD products do not incorporate the process steps of liquid crystal injection and attachment of color filters. Consequently, to minimize the total cost, it is essential to decide the appropriate product mix and capacity allocation with considerations of the resource consumption of LCD and EPD products simultaneously. In this paper, we present mathematical models to determine product mix and capacity allocation, which involve three subsystems for TFT-LCD process with consideration of net demand, inventory level, yield rates, cost, margin, outsourcing allocation, cycle time, and panel conversion rate. To demonstrate the applicability of the proposed models, we present a real-world case taken from a TFT-LCD company located in the Science-Based Industrial Park at Hsinchu, Taiwan and perform sensitivity analysis to investigate the effect on the optimal solution.     

A new semi-empirical wind turbine capacity factor for maximizing annual electricity and hydrogen production

The capacity factor is an important wind turbine parameter which is ratio of average output electrical power to rated electrical power of the wind turbine. Another main factor, the AEP, the annual energy production, can be determined using wind characteristics and wind turbine performance. Lower rated power may lead to higher capacity factor but will reduce the AEP. Therefore, it is important to consider simultaneously both the capacity factor and the AEP in design or selecting a wind turbine. In this work, a new semi-empirical secondary capacity factor is introduced for determining a rated wind speed at which yearly energy and hydrogen production obtain a maximum value. This capacity factor is expressed as ratio of the AEP for wind turbine to yearly wind energy delivered by mean wind speed at the rotor swept area. The methodology is demonstrated using the empirical efficiency curve of Vestas-80 2 MW turbine and the Weibull probability density function. Simultaneous use of the primary and the secondary capacity factors are discussed for maximizing electrical energy and hence hydrogen production for different wind classes and economic feasibility are scrutinized in several wind stations in Kuwait.     

水资源承载力分析研究

水是人们生存必不可少的资源,是生产与生活的基础,但水资源短缺,时间、空间分布不均,利用率低,已成为制约各地经济可持续发展的重要因素之一。本文所选研究区域——昌宁县正处于经济快速发展时期,水资源承载力将会影响其发展,文章综合文献分析和实际调研数据,运用科学的方法进行水资源的承载力分析,结果表明:昌宁县水资源承载力目前与社会经济的发展相适应,但远期将会有所不足,因而要求协调人与自然的矛盾,促进昌宁县的可持续发展。     

我国两部制电价制度对天然气发电企业盈利能力的影响

上海、浙江和江苏等地陆续出台了两部制电价制度,以期解决天然气发电(以下简称气电)企业成本高、经营困难等问题。为了研究该电价制度对气电企业盈利能力的影响,在对比分析上述三地电价政策和实施效果的基础上,基于不同类型机组的三大经营指标(项目财务内部收益率、经济净现值、动态投资回收期),采用项目经济性分析模型探究了不同类型燃气电厂的经济性。研究结果表明:①现行两部制电价与单一制电价相比,电价水平小幅度下降,给企业经营带来了一定的冲击,但从长远看,则有利于形成可持续的发展机制;②两部制电价是各地政府经过充分调研和测算后根据该区具体情况制定的,在该政策下多数企业处于盈亏平衡点附近,综合条件优、管理水平高的企业能取得一定的盈利,反之则亏损;③当电量电价一定且大于盈亏平衡点时,企业效益随年利用小时数的增加而提升,反之则随年利用小时数的增加而降低。结论认为:①两部制电价能起到促进企业管理和技术水平提升,引导和鼓励电力投资的作用,符合我国电力体制改革的方向;②政策制定时应针对不同时期建成的项目加以区别对待,实现上网电价、天然气价格和供热蒸气价格的"三个联动";③应建立大数据平台,实行气网、电网联合调度;④发电企业应创新管理,降低电厂建设及维护成本,提升机组效率,降低气耗。     

An effective strategy to enhance the electrochemical performance of LiNi0.6Mn0.2Co0.2O2: Optimizing a Li diffusion pathway via magnetic alignment of single-crystal cathode material under an ordinary 0.4-T magnetic field

A strategy to enhance the electrochemical performance of a single-crystal LiNi_xMn_yCo_zO₂ (NCM) electrode is proposed herein based on a preferred orientation of a Li diffusion pathway along the working direction under an ordinary 0.4-T magnetic field. Hexagonal NCM622 single crystals can be aligned along their crystallographic c-axis parallel to the applied magnetic field because the crystal has an easy magnetization axis along the c-axis. The horizontal magnetic field–oriented NCM622 cathode (HMFC) shows inhibited polarization and increased lithium-ion conductivity. The suppressed polarization promotes cyclability, increasing the specific capacity from 157.93 to 168.75 mAhg^?1 after the 100th cycle at 0.5 C. Furthermore, the increased diffusion coefficient (from 3.06 × 10^?10 cm²s^?1 to 7.12 × 10^?10 cm²s^?1) causes substantial improvement in the rate performance, achieving a high specific capacity of 130.77 mAhg^?1 at 10 C, while the electrode without magnetic treatment achieves a specific capacity of only 115.88 mAhg^?1. Owing to such a superior electrochemical performance, the HMFC electrodes show high potential for lithium-ion batteries in the EV industry. Decreasing the magnetic field from 6 to 0.4 T for cathode alignment facilitates the applicability of the proposed strategy to production lines of battery plants using commercially available permanent magnets because a magnetic field of 0.4 T is easily achievable.     

Ion Exchange of Selected Group II Metals and Lead by Crystalline Silicotitanate and Competition for Cs Exchange Sites

ABSTRACT

A series of batch contact tests were conducted to evaluate the exchange behavior of Ba, Ca, Pb, and Sr onto crystalline silicotitanate (CST) in support of an expedited Cs removal and pretreatment system at the Hanford site. Binary Na/M²⁺ and ternary Na/Cs/M²⁺ isotherms were generated to understand selectivity, capacity, and competitive impact of each analyte on Cs uptake from a simple 1 M NaOH/4.6 M NaNO₃ simulant. Analyte loading from a 0.1 M NaOH/5.5 M NaNO₃ simulant was assessed to determine the effect of hydroxide concentration on binary Na/M²⁺ isotherms. Results from binary and ternary isotherms indicated that Group II metals Ca, Sr, and Ba (and Pb) do not impact CST performance toward Cs removal at concentrations expected in Hanford tank-waste supernate.     

More than bin packing: Dynamic resource allocation strategies in cloud data centers

Resource allocation strategies in virtualized data centers have received considerable attention recently as they can have substantial impact on the energy efficiency of a data center. This led to new decision and control strategies with significant managerial impact for IT service providers. We focus on dynamic environments where virtual machines need to be allocated and deallocated to servers over time. Simple bin packing heuristics have been analyzed and used to place virtual machines upon arrival. However, these placement heuristics can lead to suboptimal server utilization, because they cannot consider virtual machines, which arrive in the future. We ran extensive lab experiments and simulations with different controllers and different workloads to understand which control strategies achieve high levels of energy efficiency in different workload environments. We found that combinations of placement controllers and periodic reallocations achieve the highest energy efficiency subject to predefined service levels. While the type of placement heuristic had little impact on the average server demand, the type of virtual machine resource demand estimator used for the placement decisions had a significant impact on the overall energy efficiency.     

挤扩支盘桩基的设计与应用

本文介绍了福建省防震减灾指挥中心桩基础的选型及设计,分析了该工程挤扩支盘桩的承载力及其沉降,同时对该桩型的经济性作了简单比较。