Papers by Keyword: Reversibility

Abstract: The electrochemical behavior of vanadium solution containing V (III) and V (IV) ion each 50% was characterized by cyclic voltammetry and chronopotentiometry with different working electrodes, temperatures, H₂SO₄ concentrations and vanadium ion concentrations. Cyclic voltammetry analysis indicated that V(IV)/V(V) redox reaction at graphite electrode showed good electrochemical activity and reversibility while V(III)/V(II) redox reaction showed bad electrochemical activity and reversibility on Pt, glassy-carbon and graphite electrode. The cathodic peak current density of V(III)/V(II) couples increased first then remained almost unchanged as temperature raised and approached a maximum at 60°C. With H₂SO₄ concentration elevated, the electrolyte became viscous and diffusion step was the controlling step. The electrochemical activity of electrolyte increased with ascending vanadium concentration, so did the reversibility of V(IV)/V(V) couples. However, no matter what vanadium concentration was, the reversibility of V(III)/V(II) couples stayed poor. Stirring in solution benefited to the anodic peak current density of V(IV)/V(V) couples whereas it did not to the cathodic peak current density of V(III)/V(II) couples. The diffusion coefficients of V(III),V(IV) were calculated as 1.17×10^-5,0.919×10^-5 cm²·s^-1 , respectively. Chronopotentiometry test indicated that solution as anolyte showed good charging performance while solution as catholyte showed poor charging performance.

Abstract: The use of composites in the field of architectural restoration is becoming more and more widespread, because of the great technical advantages they convey in many cases. But applying these materials to the Cultural Heritage poses not only technical issues, common to all the applications on the same materials, but also artistic, historical and, more generally, cultural ones. The present paper faces these issues, starting with some considerations on how they were dealt with in history, when the “new” materials were iron, steel and reinforced concrete. Then, the specific problems posed by the composite materials are discussed and some examples are shown in order to identify the correct approach to the many different cases that can arouse in the field of architectural restoration. There isn’t a single right solution for each problem, but there is a right approach that starts from the comprehension of the building’s behavior, passes through a comparison of all the possible solutions and aims at finding the best equilibrium among the technical and theoretical issues for the single case study.

Abstract: With the development of digital design and processing and the explosive growth of the demand for two-dimensional CAD engineering graphics, more attention has been paid on the security and the copyright issues of engineering graphics. In this paper, an improved reversible watermarking algorithm in wavelet domain for two-dimensional CAD engineering graphics is proposed. Firstly, the watermark information is preprocessed by compound chaos sequence. And then, block the graphic and extract all vertexes in each blocks of the 2D CAD engineering graphics, Log-polar Mapping (LPM) and wavelet transform are done to them respectively to achieve the invariance of affine transform. Finally, the encrypted watermark is embedded into detailed coefficients by using improved quantization index modulation (IQIM) scheme. Compared with the original previous algorithm, theoretical analysis and experimental results show that the proposed algorithm has not only good visibility and good reversibility, but also stronger robust against the attacks such as transformation, rotation, equal scaling and entity deleting, tampering or adding etc.

Abstract: Radial weight and rotary torque load often demand large winding current in a bearingless switched reluctance motor (BSRM). This will tend to cause magnetic saturation. But traditional mathematic model can not fit for this saturated working state, which has formatted a sever limitation. With a BSRM model in Maxwell, its magnetic saturation characteristics were analyzed, and a critical criterion was computed. Then a novel mathematic model was established with Maxwell tensor method and confirmed by Finite element computing results. It could fit for both unsaturated and saturated working state, and also satisfy reversibility condition. These were both very useful for nonlinear decoupling with state feedback method and wide application in industry process. This proposed modeling and analyzing method could also provide useful references for motor’s optimization design and control algorithm research.

Abstract: Nano-Ni(OH)₂ doped with special elements were prepared by supersonic co-precipitation method. Complex electrodes were prepared by immersion method and handwork method by mixing 8wt.% nickel hydroxides with commercial micro-size spherical nickel as the positive material of Ni-MH battery. The electrochemical performance and cyclic character affected by different electrodes’ making methods were characterized in this article. The result indicates that the discharge capacities of IM electrodes (IM electrodes mean electrodes made by handwork method) are higher than that of HM electrodes (HM electrodes mean electrodes made by handwork method). Furthermore, IM electrodes have better reversibility and higher charge efficiency than HM electrode, and lower charge potential and higher discharge plateau were also observed for IM electrodes. It's worth noting that the phenomenon is more obvious at high charge/discharge rate. When the discharge rate is 0.5C，the discharge capacity of IM electrode is higher 67.1 mAh•g ^-1 than that of HM electrode.

Abstract: This paper reports an experiment equipment which is used as reversibility research of magnetically controlled shape memory alloy (MSMA). The vibration detection is done based on dynamic reversibility of MSMA. The results show that MSMA will induce Martensitic transformation in the magnetic field. The characteristics of rapid dynamic response, high sensitivity and reversibility are found. The material is of a bright future of application in sensors and self-sensing actuator (SSA) field.

Abstract: The mechanism of lithium electrochemical reduction from its molten chloride at two different electrodes – glassy carbon and graphite – has been investigated by the cyclic voltammetry method in terms of so-called ‘thermodynamic’ or ‘material balance’ reversibility. It has been shown that the adsorption of lithium on glassy carbon and graphite plays an important role in the overall process of reduction, especially at polarization rates below 1 V/s. Lithium intercalation, probably due to small lithium atomic radius, practically does not have influence on the reversibility at these polarization rates. The process of lithium deposition on the electrodes used may be complicated by the dissolution of lithium in the melt in the whole range of polarization rates applied.