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Auxiliary power of Three-phase photovoltaic inverter is supplied by solar cells with wide input ranging from 140V to 1000V.The conventional single-switch flyback converter exists too high voltage stress in power switch to be applied in this inverter. This paper presents a dual-switch flyback converter in which the voltage stress of each switch is slightly higher than the input voltage when switches turn off, at the same time , the leakage inductance energy is recycled back into the inputside; otherwise, this topology needs no snubber circuit, so it is much more efficient than single switch flyback. The dual switch flyback converter with seven outputs is successfully applied in 10KW three phase PV inverter.

To investigate the influence of ethanol catalyzed oxidation on activity of Pd/C with different ratio of Pd and C. Pd/C catalyst samples with Pd loads of 20, 30, 40 and 50 wt% were obtained by chemical reduction reaction of PdCl₂ and NaBH₄. The samples morphology and structure were characterized by XRD and SEM. The electrocatalytic oxidation activities of ethanol were examined by cyclic voltammetry in alkaline media. The results show that a face centered cubic (FCC) Pd phase can be identified in the sample powders. The average particle size of the Pd/C powder is about 10 nm. The performance of ethanol oxidation on 40 % Pd/C electro-catalyst is better than that of the other Pd/C samples.

According to the mechanical analysis of reinforced concrete (RC) joint with special-shaped column, the formula of crack resistance considering the effect of flange length was derived on the basis of the elasticity theory, and the expressions for calculating the frame joint core effective height and width were presented. Furthermore, four RC joints with special-shaped columns were tested under low cyclic loading to investigate the mechanical behavior. At last, the calculated results predicated by the proposed formula are compared with that by experiments, and indicate that the expression has good applicability.

In order to solve the problem of face recognition, the method of feature extraction and feature selection is presented in this paper. First using Gabor filters and face image as the convolution Operator to extract the Gabor feature vector of the image and also to uniform sampling; then using the PCA + LDA method to reduce the dimension for high-dimensional Gabor feature vector; Finally, using the nearest neighbor classifier to discriminate and determine the identity of a face image. The result I get is that the sampled Gabor feature in high-dimensional space can be projected onto low-dimensional space though the method of feature selection and compression. The new and original in this paper is that the method of PCA + LDA overcomes the problem of the spread matrix singular in the class and matrix too large which is brought by directly use the LDA.

This article will combine the difference scheme of first-order upwind with the multi-conductor transmission lines equation to analysis the multi-conductor transmission lines crosstalk in the time domain. First-order upwind is a finite difference algorithm in the time domain; it has a first order accuracy, in the discontinuous solution there is no non-physics-oscillation, when simulate the signal. The flux splitting method which is applied to the first-order upwind solved the problem that the characteristic line direction of the wind type make plus or minus transformation along with the coefficient, make the programming simple. In this paper, simulation results of transmission line crosstalk in this algorithm will be compared with the traditional leapfrog scheme, to verify its effectiveness.

This paper review the chemical stabilization in arsenic contaminated soil use the in situ chemical stabilization technology. Application of iron oxide, alkaline material and phosphorus are very effective agents to fix the arsenic-contaminated soil. In addition, the future study on remediation technology for arsenic-contaminated soils was prospected.

The terpolymer was synthesized by maleic anhydride (MA), acrylic acid (AA) and methyl acrylate (MAC) and the structure was also conformed. Its scale inhibition effect was also studied in high barium and strontium ion concentration aqueous medium and simulated formation water (Ca2+, Mg2+, Ba2+, Si2+) condition. The results indicate that when additive amount of AA/MAC/MA is 60 mg/L, the inhibition rate is up to 100% and 80% for BaSO4 scale and SrSO4 scale respectively, but only 50% for calcium scale. And the scale inhibition rate moderately increases with the dosage increasing. The scale inhibition effect of AA/MAC/MA is also very obvious in simulated formation water containing low calcium ions (400 mg/L) and high barium ions (500 mg/L) as well as strontium ions (500 mg/L). It can satisfy the need of restraining composite scale (BaSO4 scale and SrSO4 scale as well as CaSO4 scale) in high calcium and barium strontium ion aqueous medium when compounded with calcium scale inhibitors CY and CX respectively.

Some of the critical and practical issues regarding the problem of condition monitoring of mobile equipment have been discussed, and an anomaly detection method without priori knowledge has been proposed. The method involves setting amplitude benchmark via spectrum amplitude in normal condition and obtaining the maximum entropy value in abnormal condition. The condition identification is achieved through estimating the amount of anomaly information in spectrum, and a measure of anomaly condition is given by the anomaly degree derived from entropy value dividing the maximum value. The sensitivity, stability and computation load of the method have been also discussed, and the method is validated on an experimental test-bed that the test bearings with different fault diameter support the motor shaft.

The corrosion resistance of a 1~2mm thick AZ91D magnesium alloy die-casting coated with epoxy varnish after phosphatizing was tested. Zinc phosphating solution was used. In the experiment, uniform paint was obtained by dipping method. Scratch test showed that the adhesion force between the coating and matrix is excellent. Within the test range the optimal phosphating temperature and time are 50°C and 1 min tested by dynamic potential scanning method. With the organic coating the corrosion current density decreased 3 orders of magnitude, the polarization resistance increased 3 orders of magnitude. The coated specimens were immersed in10% H₂SO₄, 10% NaOH and acetone for 10 days, respectively. The results showed that blistering did not occur on the paint films. This work illustrated that the simple zinc phosphating process combined with simple organic coating can meet the corrosion resistance requirements of thin-wall die casting magnesium components that require higher quality appearance.

Large cylindrical shells are widely used in many areas of aerospace, petroleum chemical industry and nuclear power, etc. The main material of large cylindrical shells is 2.25Cr-1Mo-0.25V. In the process of heavy-duty cutting cylindrical shell material, the removal rate is high, and machine condition is rough, because the viscosity of big cylindrical shell material, the large chips not easy to be broken, and the tool and workpiece often entangled affect the machining efficiency. Researh and development to apply heavy cutting under the condition of high performance cutting tool has great practical significance, because of at the same time for heavy cutting tool is less in china. This paper uses the cutting performance experiment aiming to cylindrical shell material used in different three-dimensional groove blades and studies the range of different blades broken chips and the influence of three-dimensional groove on breaking effect. The chips form of cutting cylindrical shell material is summarized. And chip-breaking groove of the best performance is optimized. The paper designs of the new heavy-duty vehicles blade well and vertfies the good effect of the new heavy-duty cutting the breaker by the results of 3 d finite element simulation. The paper provides basis for designing heavy-duty cutting.