Papers by Keyword: Voltage

Abstract: This paper is intended to find the corrosion behavior of carbon fiber reinforced Plastics (CFRPs). Some of the corrosion parameters such as 3.5% of NaCl, current density and voltage were taken into consideration. They were examined by potentiostatic polarization and scanning electron microscopy to find the corrosion rate of the CFRPs. The experiments were done by applying different voltages to the CFRPs and the corresponding current obtained will denote the corrosion rate. Based on the corrosion rates observed, the better combination can be selected in order to eliminate corrosion.

Abstract: In the present article, the experimental research of electrochemical cleaning of oil-contaminated soil is provided. The decrease of oil concentration in the soil from 1100 mg/kg down to 250 mg/kg at the current density in the range from 22 A/m² to 174 A/m² during 90 minutes is shown. It has been established that there is the limit amount of charge required for effective cleaning, which amounted to 0.96·10⁷ coulombs per kilogram of oil. The electrodes placement variant for the proposed method realization in real conditions is described. It is shown that at a voltage between the electrodes about 18 V and the cleaning efficiency of 77% the energy consumption will be 173 MJ/kg of oil.

Abstract: In the case of electrochemical discharge machining (ECDM), the number of influence factors is very high, and the complete determination of a mathematic pattern is very complicated, as proved by the time passed since the application of this processing technology and absence (for the time being) of such a system. The paper presents the method of random balance which allows influence factors hierarchization, depending on the amplitude of the effect they have on the response variable. The main influence factors will be considered: current intensity, voltage, electrode-tool – workpiece pressure, electrolyte supply intensity, relative velocity between the electrode-tool and the workpiece, electrode-tool thickness. The following response functions (performance criteria) were determined: processing productivity, processed surface roughness, flatness deviation. The experiment was made on an electrochemical discharge machining (ECDM) processing machine with a electrode-tool, stratified disk by introducing the electrolyte in it. The semi-finished material is alloy steel X40CrMoV5-1, and the material of the electrode-tool is generally use steel S235JR.

Abstract: First principle calculation based on Density Functional Theory and U correction (DFT+U) is used to investigate structural change while losing Li atom, average voltage for couple reaction, phase stability, and electronic structure of Li₂Fe_0.5Cr_0.5SiO₄. In this calculation, generalized gradient approach (GGA) of Perdew-Burke-Ernzerhof (PBE) is used for exchange-correlation functional. The initial structure of Li₂Fe_0.5Cr_0.5SiO₄ is obtained from the pmn₂₁ structure of Li₂FeSiO₄ and then the Fe site is substituted by 50 % of Cr. The results of calculation show that the optimized Li₂Fe_0.5Cr_0.5SiO₄ has a monoclinic structure, which has little different with Li₂FeSiO₄ structure. Although the delithiated system (LiFe_0.5Cr_0.5SiO₄) is taken into consideration, the structural geometry does not change significantly. It is indicated that the presence of Cr does not affect to the property of structural change. From the density of states (DOS) analysis, the presence of Cr causes the width of band gap become decrease. Therefore, the electronic properties change from insulator to semiconductor-like behavior. Average voltage for couple reaction M⁺²/ M⁺³ of Li₂Fe_0.5Cr_0.5SiO₄ is about 3.05 V which is lower than Li₂FeSiO₄. Furthermore, the formation energy for Li₂Fe_0.5Cr_0.5SiO₄ and all delithiation have a relatively positive sign compared with Li₂FeSiO₄ that mean that they have poor phase stability than Li₂FeSiO₄.

Abstract: With the help of an Assisting Electrode (AE), non-conductive ceramics can be machined using Electrical Discharge Machining (EDM) process. The AE helps start the EDM process and the intrinsic conductive layer (ICL) ensures that the electrical contact between the workpiece and the generator is maintained. However, the understanding of EDM process of non-conductive ceramics is limited due to the typical characteristic of the process: the geometric dimension of the discharge region is limited to few micrometers and the duration of the dielectric discharge is in the range of few microseconds making it difficult to directly observe the spark and the associated crater formation phenomenon. Analyzing the electrical signals during the EDM process could provide an insight of the process. This paper presents a study on analyzing the electric pulses occurring during the EDM process of a conductive workpiece (copper) and a non-conductive workpiece (Si₃N₄ ceramics). Typical pulses occurring during the EDM of a metal and a non-conductive ceramics are identified with the signal recorded at a sampling rate of 2.5 GS/s. Sampling rate of 25 MS/s is used to monitor the pulses occurring while machining a hole with depth of 1 mm. The pulses during EDM of non-conductive materials are significantly different than those during EDM of metals. Four most outstanding differences have been identified in terms of the ringing behavior of the voltage signal, the recharge time required to reach the set value of open voltage, the presence of the reverse current and the value of the peak current detected in case of Si₃N₄. The pulses monitored with lower sampling frequency was characterized and discriminated into sparks, arcs and short circuits. The percentage of the discriminated pulses for varying machining depth of the test structure has been presented.

Abstract: This paper described a kind of designation method to the power distribution system in the modern computer room .Compared with the traditional power supply socket, The Power Distribution Unit (PDU) with these functions whichcan monitor the RMS current and voltage, line frequency ,energy usage ,load limitation and the relay controlling to current leak ,over load or over current etc., There also has the wired RS-485and reserved the wireless WIFI interfaces in the PDU through which the working conditionsof equipment in the computer room can be connected and monitored by administrator at any time and place.

Abstract: In this paper proposed a method for regulating the voltage in the power system on the basis of cluster zoning using voltage sensitivity coefficient. The proposed method used to test calculations in the power supply system of the Far East with the cluster differentiation for different voltage classes and definition devices which should be coordinated while setting up. The algorithm of cluster zoning is implemented as VBScript for models in RastrWin software package.

Abstract: Voltage is a key factor not only to power system but also to user. Keep voltage steady is a hot point for researching. Paper proposed keeping steady voltage and improving power quality by using intelligent auto voltage control system. This method is based on the existing power system software and hardware platforms. It is of the advantages of mature technology, small investment, and can improve user’s power quality effectively. Second, the application of auto voltage control on textile manufacture is analyzed. It can improve running environment of textile devices and textile quality

Abstract: The modular multilevel converter (MMC) does not need clamping devices and multiple independent DC voltage source and has a modular structure which is easy to be extended to any level, share a DC side, easy to direct back to back four-quadrant operation and attracts widespread attention. Due to the use of sub-module MMC suspended on the DC side capacitor voltage divider provides synthetic AC output voltage required voltage level and therefore it is essential to the stable operation of the sub-module capacitor voltage balance of the MMC. In this paper, the factors affecting the MMC sub-module capacitor voltage balancing has been carried out a detailed analysis and this paper focuses on the nominal frequency erupted module capacitor voltage control strategies and the average low frequency sub-module capacitor voltage ripple suppression strategies.

Abstract: Unimorph cantilever is widely used in many applications with its bending and tip-deflection. In this paper, a model of the cantilever with the applied voltage and tip-deflection is presented. With the use of this model, a prototype, fabricated by VHB and polycarbonate, is estimated for its bending tip-deflection under a high voltage. And the experiment system is established with a signal generator, high voltage amplifier and laser displacement meter. The experimental results and the theoretical ones are both the same. The conclusions in this paper can be used to make further research on the deformation control of structures.