A Pulse Width Modulation Scheme With Zero-sequence Voltage Injection for Single Phase Three-level NPC Rectifiers

直流侧中点电位电压偏移是多电平中性点钳位型变流器的主要缺点。以单相三电平NPC整流器为研究对象，以实现直流侧中点电位无漂移为控制目标，以传统的单相三电平单极性载波脉宽调制方法为基础，首先提出一种基于零序电压分量注入的载波脉宽调制算法；然后在此基础上给出基于零序电压分量极限值注入的载波脉宽调制算法；并给出这2种方法的零序电压分量的设计方案；最后，对这2种方法进行了详细的理论分析、计算机仿真和1kW样机实验对比验证。研究结果表明：所提出的2种算法都能有效实现直流侧中点电位平衡控制，其中基于零序电压分量极限值注入的载波调制算法的中点电位控制具有更快动态响应速度，且其网侧电流的高次谐波主要分布在开关频率附近；而基于零序电压分量注入的载波调制算法的网侧电流高次谐波主要分布在2倍开关频率附近。但是在一个调制信号周期内，基于零序电压分量极限值注入的载波调制算法的开关切换次数比基于零序电压分量注入的载波调制算法低25％左右。

Artificial intelligence on diabetic retinopathy diagnosis: an automatic classification method based on grey level co-occurrence matrix and naive Bayesian model

AIM: To develop an automatic tool on screening diabetic retinopathy(DR) from diabetic patients.METHODS: We extracted textures from eye fundus images of each diabetes subject using grey level co-occurrence matrix method and trained a Bayesian model based on these textures. The receiver operating characteristic(ROC) curve was used to estimate the sensitivity and specificity of the Bayesian model.RESULTS: A total of 1000 eyes fundus images from diabetic patients in which 298 eyes were diagnosed as DR by two ophthalmologists. The Bayesian model was trained using four extracted textures including contrast, entropy, angular second moment and correlation using a training dataset. The Bayesian model achieved a sensitivity of 0.949 and a specificity of 0.928 in the validation dataset. The area under the ROC curve was 0.938, and the 10-fold cross validation method showed that the average accuracy rate is 93.5%.CONCLUSION: Textures extracted by grey level cooccurrence can be useful information for DR diagnosis, and a trained Bayesian model based on these textures can be an effective tool for DR screening among diabetic patients.

Features of microstructure and fracture in the transient liquid phase bonded aluminium-based metal matrix composite joints

Transient liquid phase (TLP) bonded aluminium based metal matrix composite (MMC) joints can be classified into three distinct regions, i.e. the particulate segregation region, the denuded particulate region and the base material region. The microstructure of the particulate segregation region consists of alumina particulate and Al alloy matrix with the Al 2Cu and MgAl 2O 4. It contains more and smaller alumina particulates compared with the base material region. The TLP bonded joints have the tensile strength of 150 MPa ～200 MPa and the shear strength of 70 MPa ～100 MPa . With increasing tensile stress, cracks initiate in the particulate segregation region, especially in the particulate/particulate interface and the particulate/matrix interface, and propagate along particulate/matrix interface, througth thin matrix metal and by linking up the close cracks. The particulate segregation region is the weakest during tensile testing and shear testing due to obviously increased proportion of weak bonds (particulate particulate bond and particulate matrix bond).

The Effect of Varied Dietary Crude Protein Levels with Balanced Amino Acids on Performance and Egg Quality Characteristics of Layers at First Laying Phase

Four diets were formulated to study the influence of varying crude protein levels on the performance, egg quality, serum and haematological characteristics at the first phase of laying cycle of sixty Bovan Nera laying birds that were randomly allotted to dietary treatments. The four experimental diets had five replicates each and three birds per repli-cate. Diet 1 contained 14% crude protein (CP), while diet 2 contained 15% CP, diets 3 and 4 contained 16% and 17% CP respectively. The experimental birds were fed for 10 weeks and the data collected were statistically analysed. Apparent variations recorded for all the performance characteristics such as Egg number, Hen-day production, Feed Conversion Ratio (FCR) and weight gain were significantly different (p < 0.05). The best FCR value were recorded by birds fed 17% CP (3.45), while the highest weight gain mean value were also recorded by birds fed 17% CP value. Findings indicated a direct relationship between dietary crude protein values and performance.

Application of Single-to-Single Phase Matrix Conversion in Conventional Rectifier-Inverter

The principle of single to single phase matrix electric power conversioin is further studied and the conversioin switch function is introduced into conventional rectifier inverter, thus a general character of the two conversion techniques is discovered. It is characteristic of the switch functiion to follow mains voltage distortion and mains frequency drift. By utilizing the merit, unidirectional switch duty rations of the inverter follow the variation of DC link voltage automatically, thus the size of DC link electrolytic capacitor can be reduced considerably, bringing about improved mains side power factor. Corresponding topologies and theoretical and theoretical derivations are given, and so are the simulation results, based on which it is confirmed that the single to single phase matrix conversion technique is potentially useful in large scale production, and the introduction of switch function can yield good economic returns.

Study on the Phase Behavior of Coating Matrix in Supercritical or Sub-critical Carbon Dioxide

The high-pressure phase behavior of coating-solvent-supercritical or sub-critical carbon dioxide system was investigated experimentally. The coating matrix used was 108-acrylic resin at concentration ranging from 10% to 50% (by mass) in mixtures with n-butyl acetate. The experiments were conducted in a high-pressure view cell for temperatures from 35℃ to 65℃ and for pressures from 3.0MPa to 8.0MPa. The effect of temperature, pressure and content of every component on the phase behavior of the systems was observed. Finally, the ternary phase diagram for resin-solvent-CO2 was plotted.

Transient liquid phase bonding of TiC particulate reinforced magnesium metal matrix composite (TiC_p/AZ91D)

Microstructures and mechanical properties of transient liquid phase （TLP） bonded magnesium metal matrix composite （ MMC） joints using copper interlayer have been investigated. With an increase of bonding times from 5 min to 50 min at bonding temperature of 510 ℃ , the average concentration of copper in the bonded zone decreased, the microstructure in the zone changed from Cu, α-Mg and CuMg2 to α-Mg, CuMg2 and TiC, and mechanical properties of the joint increased. The shear strength of the joint bonded at 510 ℃ for 50 min reached 64 MPa due to the metallurgical bonding of the joint and improving its homogeneity of composition and microstructure. It is favorable to increase the bonding time for improving mechanical properties of TLP bonded magnesium MMC joint.

Binary Image Steganalysis Based on Distortion Level Co-Occurrence Matrix

In recent years,binary image steganography has developed so rapidly that the research of binary image steganalysis becomes more important for information security.In most state-of-the-art binary image steganographic schemes,they always find out the flippable pixels to minimize the embedding distortions.For this reason,the stego images generated by the previous schemes maintain visual quality and it is hard for steganalyzer to capture the embedding trace in spacial domain.However,the distortion maps can be calculated for cover and stego images and the difference between them is significant.In this paper,a novel binary image steganalytic scheme is proposed,which is based on distortion level co-occurrence matrix.The proposed scheme first generates the corresponding distortion maps for cover and stego images.Then the co-occurrence matrix is constructed on the distortion level maps to represent the features of cover and stego images.Finally,support vector machine,based on the gaussian kernel,is used to classify the features.Compared with the prior steganalytic methods,experimental results demonstrate that the proposed scheme can effectively detect stego images.

Quantitative feedback theory and zero phase error tracking control combined robust control for radar truck leveling simulator

Radar leveling system is the key equipment for improving the radar mobility and survival capability. A combined quantitative feedback theory (QFT) controller is designed for the radar truck leveling simulator in this paper, which suffers from strong nonlinearities and system parameter uncertainties. QFT can reduce the plant uncertainties and stabilize the system, but it fails to obtain high-precision tracking. This drawback can be solved by a robust QFT control scheme based on zero phase error tracking control (ZPETC) compensation. The combined controller not only possesses high robustness, but greatly improves the system performance. To verify the effiectiveness and the potential of the proposed controller, a series of experiments have been carried out. Experimental results have demonstrated its robustness against a large range of parameters variation and high tracking precision performance, as well as its capability of restraining the load coupling among channels. The combined QFT controller can drive the radar truck leveling platform accurately, quickly and stably.

Frequency Domain Filtering SAR Interferometric Phase Noise Using the Amended Matrix Pencil Model

Interferometric phase filtering is one of the key steps in interferometricsynthetic aperture radar (InSAR/SAR). However, the ideal filtering results are difficult toobtain due to dense fringe and low coherence regions. Moreover, the InSAR/SAR datarange is relatively large, so the efficiency of interferential phase filtering is one of themajor problems. In this letter, we proposed an interferometric phase filtering methodbased on an amended matrix pencil and linear window mean filter. The combination ofthe matrix pencil and the linear mean filter are introduced to the interferometric phasefiltering for the first time. First, the interferometric signal is analyzed, and theinterferometric phase filtering is transformed into a local frequency estimation problem.Then, the local frequency is estimated using an amended matrix pencil at a window. Thelocal frequency can represent terrain changes, thus suggesting that the frequency can beaccurately estimated even in dense fringe regions. Finally, the local frequency is filteredby using a linear window mean filter, and the filtered phase is recovered. The proposedmethod is calculated by some matrices. Therefore, the computational complexity isreduced, and the efficiency of the interferometric phase filtering is improved.Experiments are conducted with simulated and real InSAR data. The proposed methodexhibits a better filtering effect and an ideal efficiency as compared with the traditionalfiltering method.

Voltage and Current Mode Vector Analyses of Correction Procedure Application to Clarke’s Matrix—Symmetrical Three-Phase Cases

Clarke’s matrix has been applied as a phase-mode transformation matrix to three-phase transmission lines substituting the eigenvector matrices. Considering symmetrical untransposed three-phase lines, an actual symmetrical three-phase line on untransposed conditions is associated with Clarke’s matrix for error and frequency scan analyses in this paper. Error analyses are calculated for the eigenvalue diagonal elements obtained from Clarke’s matrix. The eigenvalue off-diagonal elements from the Clarke’s matrix application are compared to the correspondent exact eigenvalues. Based on the characteristic impedance and propagation function values, the frequency scan analyses show that there are great differences between the Clarke’s matrix results and the exact ones, considering frequency values from 10 kHz to 1 MHz. A correction procedure is applied obtaining two new transformation matrices. These matrices lead to good approximated results when compared to the exact ones. With the correction procedure applied to Clarke’s matrix, the relative values of the eigenvalue matrix off-diagonal element obtained from Clarke’s matrix are decreased while the frequency scan results are improved. The steps of correction procedure application are detailed, investigating the influence of each step on the obtained two new phase-mode transformation matrices.

3D Gray Level Co-Occurrence Matrix Based Classification of Favor Benign and Borderline Types in Follicular Neoplasm Images

Since the efficiency of treatment of thyroid disorder depends on the risk of malignancy, indeterminate follicular neoplasm (FN) images should be classified. The diagnosis process has been done by visual interpretation of experienced pathologists. However, it is difficult to separate the favor benign from borderline types. Thus, this paper presents a classification approach based on 3D nuclei model to classify favor benign and borderline types of follicular thyroid adenoma (FTA) in cytological specimens. The proposed method utilized 3D gray level co-occurrence matrix (GLCM) and random forest classifier. It was applied to 22 data sets of FN images. Furthermore, the use of 3D GLCM was compared with 2D GLCM to evaluate the classification results. From experimental results, the proposed system achieved 95.45% of the classification. The use of 3D GLCM was better than 2D GLCM according to the accuracy of classification. Consequently, the proposed method probably helps a pathologist as a prescreening tool.

The Formula of Dependence of Mechanical Characteristics of Materials on Crystalline Phase Composition in the Matrix

Objective: For materials science and generally, for long-term operation of work-pieces in industry the significant role is attributed to dependence of macro-mechanical properties of consolidated body on crystalline phase composition, its dimensions, form, distribution in matrix and the form factor. While working in responsible fields of technology of ceramics and ceramic composites the above referred properties are attributed extremely great role with the view of durability and endurance at the terms of heavy mechanical loads. For description of the resistance of any concrete type work-piece, the crystalline phase plays the greatest role in mechanical strength or deformation of any material. It plays the important role in correlative explanation of materials mechanics and matrix properties. In our case, in the process of destruction of ceramic materials and composites, which will give us exhaustive response to the role of macro- and micro-mechanical properties of materials, the role of a macro- and micro-structural component, that is, of crystalline phase in the process of transition of stable state of materials into meta-stable state is extremely big. Our study aims to develop a formula of dependence of macro-mechanical properties of ceramic and ceramic composites on crystalline phase, the most powerful component of their structure, which will enable theorists and practitioners to select and develop technologies and technological processes correctly. Method: On the basis of the study of micro- and macro-mechanical properties of ceramics and ceramic composites and the morphology of crystalline phase and the analysis of the study we determined and created parameters of the formula. Results: The formula covers macro-mechanical properties, that is when the work-piece is thoroughly destructed: mechanic at bending at three and four-point load, mechanic at contraction;among morphological characteristics: composition of crystalline phase and their spreading in matrix, their sizes, form factor;correlative dependence of the above listed properties. Absolutely new definition of a factor of spreading of crystalline phase in matrix is offered. Conclusion: The created formula is of consolidated nature and it can be used in technology of any ceramic material and ceramic composites. The formula will help practitioners to plan correctly and fulfill accurately all positions of technology of production of work-pieces, to carry out the most responsible thermal treatment process of technology of manufacture of work-pieces;to determine correlation between mechanical and matrix properties of materials.

Formation process, microstructure and mechanical property of transient liquid phase bonded aluminium-based metal matrix composite joint

The formation process, microstructure and mechanical properties of transient liquid phase (TLP) bonded aluminium based metal matrix composite (MMC) joint with copper interlayer were investigated. The formation process of the TLP joint comprises a number of stages: plastic deformation and solid diffusion (stage 1), dissolution of interlayer and base metal (stage 2), isothermal solidification (stage 3) and homogenization (stage 4). The microstructure of the joint depends on the joint formation process (distinct stages). The plastic deformation and solid diffusion in stage 1 favoure the intimate contact at interfaces and liquid layer formation. The microstructure of joint consists of aluminium solid solution, alumina particle, Al 2Cu and MgAl 2O 4 compounds in stage 2. The most pronounced feature of joint microstructure in stage 3 is the alumina particle segregation in the center of the joint. The increase of joint shear strength with increasing bonding temperature is mainly attributed to improving the fluidity and wettability of liquid phase and decreasing the amount of Al 2Cu brittle phase in the joint. The principal reason of higher bonding temperature (>600 ℃) resulting in lowering obviously the joint shear strength is the widening of alumina particle segregation region that acts as a preferential site for failure. The increase of joint shear strength with increasing holding time is mainly associated with decreasing the amount of Al 2Cu brittle phase and promoting homogenization of joint.

A scheme for conditional quantum phase gate via bimodal cavity and a∧-type three-level atom

We propose a scheme to implement a two-qubit conditional quantum phase gate for the intracavity field via a single three-level ∧-type atom driven by two modes in a high-Q cavity. The quantum inforraation is encoded on the Fock states of the bimodal cavity. The gate＇s averaged fidelity is expected to reach 99.8%.

On the liquid-phase technology of carbon fiber/aluminum matrix composites

The main problems with the liquid-phase technology of carbon fiber/aluminum matrix composites include poor wetting of the fiber with liquid aluminum and formation of aluminum carbide on the fibers’surface.This paper aims to solve these problems.The theoretical and experimental dependence of porosity on the applied pressure were determined.The possibility of obtaining a carbon fiber/aluminum matrix composite wire with a strength value of about 1500 MPa was shown.The correlation among the strength of the carbon fiber reinforced aluminum matrix composite,the fracture surface,and the degradation of the carbon fiber surface was discussed.

Comparative analysis of energy-level splitting of Pr^(3+) doped in LiYF_4 and LiBiF_4 crystals:a complete energy matrix calculation

Based on the combination of Racah＇s group-theoretical consideration with Slater＇s wavefunction, a 91 ×91 complete energy matrix is established in tetragonal ligand field D2d for Pr3＋ ion. Thus, the Stark energy-levels of Pr3＋ ions doped separately in LiYF4 and LiBiF4 crystals are calculated, and our calculations imply that the complete energy matrix method can be used as an effective tool to calculate the energy-levels of the systems doped by rare earth ions. Besides, the influence of Pr3＋ on energy-level splitting is investigated, and the similarities and the differences between the two doped crystals are demonstrated in detail by comparing their several pairs of curves and crystal field strength quantities. We see that the energy splitting patterns are similar and the crystal field interaction of LiYF4：Pr3＋ is stronger than that of LiBiF4：Pr3＋.

Methods for Derivation of Density Matrix of Arbitrary Multi-Mode Gaussian States from Its Phase Space Representation

We present a method for derivation of the density matrix of an arbitrary multi-mode continuous variable Gaussian entangled state from its phase space representation.An explicit computer algorithm is given to reconstruct the density matrix from Gaussian covariance matrix and quadrature average values.As an example,we apply our method to the derivation of three-mode symmetric continuous variable entangled state.Our method can be used to analyze the entanglement and correlation in continuous variable quantum network with multi-mode quantum entanglement states.

Determination of Tebuconazole Residue in Apples and Vegetables by Matrix Solid Phase Dispersion-Gas Chromatography

[ Objective] The study aimed to determine tebuconazole residue in apples and vegetables using matrix solid phase dispersion-gas chro- matography （MSPD-GC）. [ Method] The effects of extraction and determination conditions on the detection of tebuconazole left in apples and veg- etables were analyzed, and the optimum extraction conditions were determined. [ Result] The recovery rate of tebucenazole was the highest when the ratio of a sample to florisil dispersant was 1 ： 4, and the mixture of hexane and acetone （ 1 ： 1 ） with total volume of 8 ml was as the eluant. Under the optimum conditions, the relative standard deviation （RSD） of the method was 4.9% -7.6%, and the detection limit was 0.1 tJg/g, while the re- covery rate of tebuconazole changed from 86.7% to 95. 2% . [ Conclusion] The method was simple, accurate, sensitive and applicable to the de- termination of tebuconazole in aaricultural Droducts.

Recent progress in ternary mixed matrix membranes for CO_(2) separation

Mixed matrix membranes(MMMs)could combine the advantages of both polymeric membranes and porousfillers,making them an effective alternative to conventional polymer membranes.However,interfacial incompatibility issues,such as the presence of interfacial voids,hardening of polymer chains,and blockage of micropores by polymers between common MMMsfillers and the polymer matrix,currently limit the gas sep-aration performance of MMMs.Ternary phase MMMs(consisting of afiller,an additive,and a matrix)made by adding a third compound,usually functionalized additives,can overcome the structural problems of binary phase MMMs and positively impact membrane separation performance.This review introduces the structure and fabrication processes for ternary MMMs,categorizes various nanofillers and the third component,and summarizes and analyzes in detail the CO_(2) separation performance of newly developed ternary MMMs based on both rubbery and glassy polymers.Based on this separation data,the challenges of ternary MMMs are also discussed.Finally,future directions for ternary MMMs are proposed.