Potassium ions stabilized hollow Mn-based prussian blue analogue nanocubes as cathode for high performance sodium ions battery

Mn-based Prussian blue analogue is regarded as one of the promising cathodes for sodium ions battery owing to its high theoretical capacity and low cost. However, the unstable structure during charging/discharging process and the poor cycle life hinder its commercial application. In this work, potassium ions stabilized hollow Mn-based Prussian blue analogue is synthesized through a simple sodium citrate assisted method using for cathode of sodium-ions batteries. Although unique hollow structure could suffer volume variation during charging/discharging process, the K⁺ is introduced to further stabilize its structure. The PBAs cathode exhibits a high reversible specific capacity of 128 mA h g^?1 at 50 mA and superior rate performance of 72 mA h g^?1 at a high current density of 3200 mA g^?1, which is attributed to its stable structure and enhanced sodium ions transport kinetics. Ex-situ XRD/Raman tests and electrochemical measurements further prove the synergistic effect of various alkali ions (K⁺/Na⁺) and unique hollow structure. They work together to improve the structural stability and promote sodium ions diffusion rate of Mn-based PBAs.     

Capacitance-dominated hierarchical porous three-dimensional carbon framework enhanced Prussian blue analogue as superior cathode for sodium-ion batteries

The 3D framework carbon is an ideal host of active materials for energy storage batteries. In this work, K_xNa_yMn[Fe(CN)₆] (KNMF) nanocubes were in-situ grown on hierarchical porous 3D framework carbon (3DFC) to construct a composite cathode (KNMF@3DFC) for sodium-ion batteries. Owing to the hierarchical porous structure and large specific surface area, the highly conductive 3DFC offers abundant active sites for sodium storage and contributes to extra capacity. The considerable content of surface capacitance-dominated sodium storage of KNMF@3DFC composite cathode reveals faster charge transfer and better reaction kinetics, conducing to its rate capability. Ex-situ XRD/Raman measurements further reveal well structural stability of KNMF@3DFC during the whole cycle. Consequently, the KNMF@3DFC composite electrode reveals excellent rate performance and superior long-term cycling stability. Combining active materials with 3D framework carbon to enable a capacitance-dominated sodium storage mechanism is a promising strategy to stimulate the development of advanced electrode materials.     

A multi‐objective evolutionary optimization of fuzzy controller for energy conservation in air conditioning systems

This paper presents the use of evolutionary optimization approach to design and tune smart fuzzy controllers for heating, ventilation, and air conditioning systems or HVAC. The objective is to optimize energy consumption while accounting for user comfort requirements. The problem of energy conservation in air conditioning systems becomes a multi‐objective optimization constrained problem, which enlarges the solution search space. To solve this problem, a multi‐objective evolutionary optimization technique based on genetic algorithm (GA) is proposed. A physical experimental setup is constructed for data collection and formulation of mathematical model. A fuzzy controller is initially designed through expert knowledge, and GA is then used to tune the rules and membership functions of the fuzzy controller in order to optimize multiple objectives. Simulations and real experiments are compared to determine the effectiveness of the proposed strategy. As compared to the controller present in the real experimental air conditioner, approximately 15% energy is successfully saved with no increase in average individual dissatisfaction or discomfort index. Also, a decrease in peak individual dissatisfaction or discomfort index from 91% to 62% is observed. Copyright © 2013 John Wiley & Sons, Ltd.     

变压器类负荷模拟量控制晶闸管调功器

介绍一种适用于变压器类负荷的晶闸管调功器,采用模拟量控制方式。文中阐述了采用脉冲宽度随导通角而变化的触发脉冲列的特殊方法,实现软启动和软关断的措施。     

All-plastic electrochromic devices based on PEDOT as switchable optical attenuator in the near IR

Advanced materials for IR applications such as thermal control in spacecraft applications or variable optical attenuators which could replace the present systems have been sought. The use of electrochromic devices based on conducting polymers will add lightness and flexibility to the final device in order to overcome the limitations of the present materials used in IR applications. In this work, we present a new all-plastic electrochromic device with optical contrast (%ΔT) of 44% at 1971 nm in the IR region based on PEDOT formulations and ionic liquid blends as electrolytes. The switching time of the device is in the order of a few seconds, with a t_c 2.7 s and t_b 3.8 s.     

可编程控制器在声能吹灰控制中的应用

介绍了利用可编程控制器控制声能吹尘并节能的工艺过程及 控制方法,可编程控制器在该领域的应用不但恰当而且有效益。     

Kinetic and thermodynamic studies of hydrogen adsorption on titanate nanotubes decorated with a Prussian blue analogue

In this paper, the kinetic and thermodynamic hydrogen adsorption characteristics of a novel composite comprising TiNT decorated with the Prussian blue analogue Cd₃Fe^III are investigated at high pressures and different temperatures. It is shown that boundary-layer (film) diffusion does not play a limiting role in the mass transport of hydrogen inside the composite material. The diffusion coefficient and time constant at different temperatures and pressures are calculated using an intra-particle diffusion model. The results suggest that molecular diffusion dominates Knudsen diffusion in the composite material. There are clear improvements in the mass transport characteristics compared to bulk Cd₃Fe^III. The Gibb's free energy is estimated by fitting isotherm equilibrium data to the Dubinin–Astakhov model and is used to calculate the enthalpy and the entropy of adsorption. The calculated value of enthalpy is characteristic of a physisorption process and is considerably higher than the activation energy for intraparticle diffusion, suggesting that the rate-limiting step of hydrogen is not mass transport to the adsorption sites.     

点燃式发动机上应用甲醇燃料的试验研究

本文介绍了在四冲程和二冲程汽车用点燃式发动机上,应用甲醇燃料(M 100)的情况。试验结果表明,内燃机使用甲醇燃料有利于综合利用资源,而且很容易改装成甲醇发动机。     

Preparation of graphite carbon/Prussian blue analogue/palladium (GC/PBA/pd) synergistic-effect electrocatalyst with high activity for ethanol oxidation reaction

In this paper, newly graphite carbon/Prussian blue analogue/palladium (GC/PBA/Pd) synergistic-effect electrocatalyst for ethanol oxidation reaction were developed, with Co-based PBA (Co₃[Co(CN)₆]₂) as a co-catalyst. Structural analysis shows that the Co₃(Co(CN)₆)₂ nanoparticles were highly dispersed and inlaid on surface of GC nanosheets with outstanding structural stability. The GC/Co₃(Co(CN)₆)₂/Pd electrocatalyst exhibits significantly enhanced electrocatalytic activity towards ethanol oxidation with a maximum mass activity of 2644 A g^?1 Pd GC/Pd, which is more than double that of GC/Pd electrocatalyst (1249 A g^?1). Excellent electrochemical stability is also demonstrated for this GC/Co₃(Co(CN)₆)₂/Pd electrocatalyst. The enhanced electrocatalytic activity can be attributed to the synergistic effects of GC support and Co₃(Co(CN)₆)₂ promoter on the Pd electrocatalysts, in which Co₃(Co(CN)₆)₂ acts as a co-catalyst and GC acts as a conductive support.     

Development of an experimental prototype of an integrated thermal management controller for internal-combustion-engine-based cogeneration systems

As a kind of distributed energy system, internal-combustion-engine-based cogeneration system is attracting increasing attentions for its environmental friendly and economic qualities. Some problems are encountered in the application, such as jacket water temperature control and the recovery/management of waste heat. To solve these problems, the concept of “integrated thermal management controller” (ITMC) is presented in this paper. Experimental prototype is established to verify its operation principle. Experimental results show that the prototype can effectively control the temperature in variable working conditions. Water/R22 is a good combination of working fluid/non-condensable gas in temperature control. The regulation of hot water flow rate is an effective method to adjust the heat allocated to heat consumer.     

一个燃压机组故障的典型处理过程

针对涩宁兰输气管道Taurus60燃压机组因防喘阀无法关闭导致机组无法正常运行的现象,对可能的几个原因进行了分析并逐一排查,最终找出了问题所在并圆满解决。通过总结故障排查过程,试图给出燃压机组故障处理所需的基本技能以及通用的处理方法,使相关技术人员快速处理燃压机组故障,缩短故障处理时间,减少因燃压机组停运造成的损失。本方法对于其它旋转设备的故障处理也有可借鉴之处。     

Comparison of charge accumulation and transport in nanostructured dye-sensitized solar cells with electrolyte or CuSCN as hole conductor

The charge transport properties of the dye-sensitized solar cells consisting of Ru(dcbpyH₂)₂(NCS)₂-sensitized nanostructured TiO₂ with either redox electrolyte or CuSCN as hole conductor have been compared. The electron transport time and the electron charge in the TiO₂ varies in a similar way with the incident light intensity for both hole conductors: electron transport becomes faster and electron accumulation increases with increasing light intensity. Electron transport in the CuSCN-based cells is significantly faster than in electrolyte cells under conditions where the accumulated charge is equal. An ultra-thin aluminum oxide layer on the nanocrystalline titanium oxide has a beneficial effect as it reduces the recombination and increases the open-circuit potential.     

Power capture optimization of variable-speed wind turbines using an output feedback controller

One of the major factors that can increase the efficiency of wind turbines is through control of the rotor speed to track the optimal value. A high performance controller can significantly increase the amount of energy that can be captured from wind. The main problem associated with controller design is the presence of uncertainties in the dynamic model of the system, which can be associated with unknown constant parameters and/or unmodeled dynamics such as external disturbances. several adaptive and robust control approaches have been developed to account for these uncertainties. In this paper, a robust controller is presented that compensates for both types of uncertainties; the full mechanical and electrical dynamics of the turbine are considered. These dynamics require acceleration of the rotor to provide feedback information which is not available in sufficiently accurate form during practice. Therefore, in this approach, an observer estimates this information using the speed of the rotor as the output, with the estimation error considered during the stability analysis. This presents one of the main advantages of the approach; the simulation results illustrate the effectiveness of the controller.     

Durability evaluation of electrochromic devices – an industry perspective

Several issues regarding the working environment and the stability of prototype electrochromic (EC) windows are discussed. In this study, we focus on issues to attain confidence in the durability of EC devices for energy efficient architectural glazing. The environmental conditions that EC glazing are subjected to, are detailed and discussed. Comparisons are made to actual prototype, real time EC window exposure testing. Testing of EC mirrors and liquid crystal glazing is compared to EC glazing. During testing of glazing in Arizona, surface temperatures of 56–65°C (uncolored-colored) were measured on EC glazing panels, with ambient air temperature of 40°C. The usual panel heating rate ranged from 14.3°C/h to 21°C/h. The steepest swing occurred during a thunderstorm with a 40°C rise in 15 min. In EC testing studies in Yokohama, it was determined that indoor testing and outdoor testing did not achieve the same results, with outdoor testing being more severe. It was also determined that the critical test parameters were temperature, solar intensity (especially UV), depth of coloration, charge capacity and change in transmittance. As a result of this study, we recommend a regimen of testing covering thermal cycling, UV stability, thermal storage and thermal shock.     

湿法脱硫除尘一体化装置应用中的问题及解决措施

从湿式脱硫系统运行参数和系统结构两个方面,论述了湿法脱硫除尘一体装置在工业化运行中存在的问题,指出pH值,露点温度的控制和脱硫装置有关部件的设计,是保证装置稳定高效运行的关键因素,并结合实践提出了改善和解决湿法脱硫存在问题的技术措施。     

Temperature dependence of the optical transitions in electrodeposited Cu2O thin films

Cu₂O films on flexible copper and molybdenum (Mo) substrates were prepared by electrodeposition form an alkaline bath. The as-deposited films were p-type and the XRD analysis revealed that the film contains only the Cu₂O phase. The thickness of the films was calculated from the interference fringes in the reflection spectra. The Au/Cu₂O Schottky diodes were prepared by sputtering a 15 nm thick layer of very pure gold onto the Cu₂O films on Mo substrate. The probable optical transitions near the band edge were calculated from the spectral response of the device. The band gap calculated at various temperatures show a linear dependence on temperature and the absolute zero value of the band gap is deduced as 2.206 eV. The 2.493 eV direct transition observed in the room temperature shows a temperature dependence. Evidence of phonon assisted indirect transitions were observed at various temperature regions.     

Temperature dependence of the optical transitions in CdTe thin film – Investigation with photoresponse spectra

The CdTe thin films have been prepared by electrochemical method from a bath solution containing cadmium sulfate and tellurium dioxide. Schottky devices of the type Au/CdTe were prepared and the spectral response of the device has been investigated. The direct and indirect transitions in the 1.3–1.6 eV region were calculated from the normalized spectral response data. The temperature dependence of the band gap have been investigated and correlated with the theory. The band gap of CdTe at absolute zero temperature is estimated as 1.61 eV and that the rate of change of E_g with temperature is calculated as −0.4 meV/K. The 1.407 eV indirect transition involves a trap level near the conduction band edge. The indirect transition also exhibits temperature dependence.     

Design of the PID temperature controller for an alkaline electrolysis system with time delays

Electrolysis systems use proportional–integral–derivative (PID) temperature controllers to maintain stack temperatures around set points. However, because of heat transfer delays in electrolysis systems, the manual tuning of PID temperature controllers is time-consuming, and temperature oscillations often occur. This paper focuses on the design of the PID temperature controller for an alkaline electrolysis system to achieve fast and stable temperature control. A thermal dynamic model of an electrolysis system is established in the frequency domain for controller designs. Based on this model, the temperature stability is analysed by the root distribution, and the PID parameters are optimized considering the temperature overshoot and the settling time. The performance of the optimal PID controllers is experimentally verified. Furthermore, the simulation results show that the before-stack temperature should be used as the feedback variable for small lab-scale systems to suppress stack temperature fluctuations, and the after-stack temperature should be used for larger systems to improve the economy. This study helps ensure the temperature stability and control of electrolysis systems.     

Use of strontium titanate (SrTiO3) as an anode material for lithium-ion batteries

Strontium titanate nanoparticles have been synthesized using a combination of sol-precipitation and hydrothermal techniques for subsequent testing as an anode material for lithium-ion batteries. The potentials associated with lithiation are 0.105 V and 0.070 V vs. Li/Li⁺ and 0.095 V and 0.142 V vs. Li/Li⁺ during de-lithiation. These potentials are significantly lower than the 1.0 V to 1.5 V vs. Li/Li⁺ typically reported in the literature for titanates. In an attempt to improve the lithiation and de-lithiation kinetics, as well as capacity retention, SrTiO₃ nanoparticles were platinized using a photoinduced reduction of chloroplatinic acid. No significant changes in the morphology or crystal structure of the platinized nanoparticles were observed as a result of the reduction reaction. The voltage profile, charge and discharge kinetics, and cyclability of the platinized SrTiO₃ nanoparticles are compared to that of the non-platinized SrTiO₃ nanoparticles.     

Use of clays as liners in solar ponds

An alternative to synthetic materials for use in solar pond liners is to select clayey soils as hydraulic barriers. This option reduces the cost of construction and the risk of contamination of subsoil and groundwater by hot brines. This paper deals with the physical, chemical and hydraulic properties of different soils tested mainly as compacted clay liners. The underdeveloped nations have the option to use this type of liner, but before doing so several tests are recommended, including those for soil and water composition, permeability, plasticity and X-ray diffraction analysis. In this investigation the following samples are analyzed: native clayey soils with illite, montmorillonite and halloysite, treated and non-treated bentonites in powder and granulated form, a mixture of zeolite and sodium bentonite, and industrial minerals composed largely of halloysite, kaolinite and attapulgite selected clays. Neutral salt aqueous solutions (NaCl and KCl) at different concentrations and under temperature gradients were used for compatibility testing conducted on these specimens. Experiment setup and particular testing procedures are also discussed.