Fabrication and properties of foam geopolymer using circulating fluidized bed combustion fly ash

In recent years, circulating fluidized bed combustion fly ash (CFA) is used as a raw material for geopolymer synthesis. Hydrogen peroxide was employed as a foaming agent to prepare CFA-based foam geopolymer. The particle distribution, mineral composition, and chemical composition of CFA were examined firstly. Geopolymerization products were characterized by mechanical testing, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF). The CFA-based foam geopolymer was successfully fabricated with different contents of hydrogen peroxide and exhibited uncompleted alkali reaction and reasonable strength with relative low atomic ratios of Si/Al and Si/Na. Type-C CFA in this research could be recycled as an alternative source material for geopolymer production.     

Performance improvement of car body structure in 100 % frontal impact

During the 100%front impact,all the parts of front car will participate in the course;the crash stiffness of bodywork will also reach the peak.During the crash,rational structure of bodywork can resist the distortion,absorb more energy and get better mode of distortion and low deceleration rate,so as to meet the performance of crash safety.The paper mainly makes optimization analysis based on the problems of front side rails,subframe,firewall,and optimization cases are confirmed which can decrease the intrusion and deceleration rate of the whole car.The structure of bodywork after optimization can meet the performance of crash safety.     

Comparative analysis by simulating and testing pole impact for hot stamping front crossbeam of automobile

Hot stamping 22MnB5 steel plate with ultra-high strength has been widely used for body structural members in consideration of automobile safety and lightweight.This paper presents a verification program of simulating and testing pole impact in order to verify if the front crossbeam reinforcement assembly can meet the design requirements,reduce the overall vehicle simulation and test cost and shorten the operation period.In the same condition,the simulation proved conforming to the design requirements;however,the bumper cracked at the impacting point in the course of pole impact test.The analysis of the crack by optical microscope,Vickers and scanning electron microscope indicates that mixture of ferrite,bainite and martensite was produced in the weld heat-affected zone of the 340/590DP tow hook holder and the 22MnB5 front crossbeam;therefore,their hardness and mechanical property were reduced obviously,so that they fractured when impacted.No welding process with continuous weld but spot welding or other bonding method may be employed for the reason that the capacity of the 22MnB5 steel plate in the weld heat-affected zone was reduced obviously.     

A real-time data smoothness method based on xPC-Target

A method of real-time data smoothness which is applied in a hardware-in-the-loop (HIL) simulation platform for a plug-in hybrid electric vehicle synthetical power device is described. The input signal of the platform comes from a AC/DC switch power with output containing noises. A linear slide average arithmetic is applied to smooth the noises. To average a certain number input sample signals, this method can decrease the noises voltage level, which meet the requirement of the simulation platform. The efficiency and signal delay time are presented to describe the result of this method, and a statistical index is used to judge the arithmetic's efficiency. The tests results show that the arithmetic fit the requirement of the HIL simulation platform.     

Cold-state spout-fluidizing characteristics of high-carbon ferromanganese powders

The spout-fluidizing characteristics of high-carbon ferromanganese powders with different sizes and masses were studied via a plexiglass spout-fluidized bed with an inner diameter of 30 mm and a height of 1000 mm. The relationships between bed voidage and such parameters as bed height, particle size, fluidizing air velocity, and air flow were obtained. Experimental results show that the powder material with high density can be fluidized in the spout-fluidized bed where the particle size is a key factor influencing the quality of fluidization.     

Comparative study on the passivation layers of copper sulphide minerals during bioleaching

The bioleaching of copper sulphide minerals was investigated by using A. ferrooxidans ATF6. The result shows the preferential order of the minerals bioleaching as djurleite>bornite>pyritic chalcopyrite>covellite>porphyry chalcopyrite. The residues were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is indicated that jarosite may not be responsible for hindered dissolution. The elemental sulfur layer on the surface of pyritic chalcopyrite residues is cracked. The compact surface layer of porphyry chalcopyrite may strongly hinder copper extraction. X-ray photoelectron spectroscopy (XPS) further confirms that the passivation layers of covellite, pyritic chalcopyrite, and porphyry chalcopyrite are copper-depleted sulphide Cu₄S₁₁, S8, and copper-rich iron-deficient polysulphide Cu₄Fe₂S₉, respectively. The ability of these passivation layers was found as Cu₄Fe₂S₉>Cu₄S₁₁>S₈>jarosite.     

Physical model of fluid flow characteristics in RH-TOP vacuum refining process

To understand the characteristic of circulation flow rate in 250-t RH-TOP vacuum refining process, the l:4 water model test was established through the bubble behavior and gas holdup in the up-leg to investigate the effects of different processes and equipment parameters on the RH circulation flow rate. With the increases of lifting gas flow rate, lifting bubble travel, and the internal diameter of the up-leg, and the decrease of nozzle diameter, the work done by bubble floatage and the circulation flow rate increase. The expression of circulation flow rate was derived from the regression analysis of experiment data. Meanwhile, the influences of vacuum chamber pressure and nozzle blockage situation on the circulation flow rate were discussed in detail by the bubble behavior and gas holdup in the up-leg. It is necessary to maintain a certain vacuum chamber liquid level in the molten steel circulation flow. Compared with a nozzle with symmetrical blockage in the up-leg, when a nozzle with non-symmetrical blockage is applied, the lifting gas distribution is non-uniform, causing a great effect on the molten steel circulation flow and making the circulation flow drop largely.     

电极活化二氧化碳诱导合成碳酸二甲酯

 针对近年来利用甲醇和CO₂直接反应制备碳酸二甲酯研究中反应条件苛刻、工艺设备复杂、甲醇转化率低等不足问题,本文研制一种固碳溶液,其CO₂饱和质量浓度达0.528 g/mL;在固碳溶液中用电解的方式对CO₂进行活化,并在电解过程中不断补充CO₂至饱和,得到电解活化液;用碘甲烷作诱导剂,使其与甲醇在60℃回流120 min,制得碳酸二甲酯,纯度为99.0%,转化率为99.6%（以甲醇质量计）,反应过程环保、条件温和。     

高容量正极材料Li[Li0.17Mn0.58Ni0.25]O2的倍率性能

采用碳酸盐共沉淀工艺,通过控制结晶合成了显微形貌呈现较大差异的Li[Li0.17Mn0.58Ni0.25]O2样品,并对样品进行了X射线衍射、高分辨透射电镜、场发射扫描电镜分析以及恒电流充放电和交流阻抗测试.合成的Li[Li0.17Mn0.58-Ni0.25]O2材料均具有良好的结晶度,可标定为α-NaFeO2结构(空间群R3m).其中,具有一次颗粒沿六方棱柱长轴方向形成“簇形”团聚的材料比其他样品具有优异的倍率性能,在电压范围为2.5～4.8 V,倍率分别为0.5C、1.0C和3.0C时,Li[Li0.17Mn0.58Ni0.25]O2材料首次放电比容量分别达到205.4、195.5和158.5 mA·h·g-1,100次循环后放电比容量保持在203.5、187.2和151.2 mA·h·g-1,容量保持率分别为99％、96％和95％.Li[Li0.17Mn0.58Ni0.25]O2材料特殊的颗粒团聚状态降低了界面的电荷转移阻抗,材料的倍率性能显著提高.同时,文中对Li[Li0.17Mn0.58Ni0.25]O2材料在不同截止电压下的电化学性能进行了对比分析.     

Electrochemical biosensors and logic devices based on aptamers

Aptamers are molecular recognition elements with high specificity that are selected from deoxyribonucleic acid/ribonucleic acid (DNA/RNA) library. Compared with the traditional protein recognition elements,aptamers have excellent properties such as cost-effective,stable,easy for synthesis and modification. In recent years,electrochemistry plays an important role in biosensor field because of its high sensitivity,high stability, fast response and easy miniaturization. Through the combination of these two technologies and our rational design,we constructed a series of biosensors and biochips that are simple,fast,cheap and miniaturized. Firstly,we designed an adenosine triphosphate (ATP) electrochemical biosensor based on the strand displacement strategy. We can detect as low as 10 nmol/L of ATP both in pure solution and complicated cell lysates. Secondly,we creatively split the aptamers into two fragments and constructed the sandwich assay platform only based on single aptamer sequence. We successfully transferred this design on biochips with multiple micro electrodes (6×6) and accomplished multiplex detection. In the fields of biochips and biocomputers,we designed several DNA logic gates with electric (electrochemical) signal as output which paves a new way for the development of DNA computer.