• Volume 38,Issue 2,2017 Table of Contents
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    • >Special Column: National Young Scholar/Local Science Foundation
    • Reliability modeling technology for CNC PCB performance degradation based on competing failure

      2017, 38(2):101-107. DOI: 10.7535/hbkd.2017yx02001

      Abstract (2263) HTML (0) PDF 1.66 M (2942) Comment (0) Favorites

      Abstract:To comprehensively, objectively, and accurately predict the reliability of CNC PCB under the action of the external environment stress and the internal circuit, and verify whether the reliability design of CNC system could meet the requirement and the system could reliably work, the CNC PCB is investigated. Starting from crucial and key problems of the reliability ana-lysis and evaluation, on the basis of review of the failure mechanism and degradation failure analysis, the typical accelerated model of CNC PCB is proposed in consideration of the multiple failure mechanism competing, which provides a new method to accurately analyze and evaluate the reliability of CNC PCB. Then in consideration of the failure mechanism and relation among multiple failure modes, a thought on building the typical accelerated model of CNC PCB is advanced. Finally, through analyzing the correlation and quantifying the proportions of all failure mechanisms based on test data, the accelerated model of CNC PCB is proposed on competing failure. It provides a new method to analyze and evaluate the reliability of CNC PCB accurately.

    • Research advances in contact model and mechanism configuration for nut shelling manipulation based on metamorphic method

      2017, 38(2):108-115. DOI: 10.7535/hbkd.2017yx02004

      Abstract (2600) HTML (0) PDF 1.57 M (3352) Comment (0) Favorites

      Abstract:Nuts are the important economic forest tree species of China. De-shell is the key operation of nut deep processing. There are some problems in the current nut cracking devices such as the low decorticating rate, the high nuts losses rate and nutmeat integrity problems, etc.. The foundation of force analysis is to establish contact model for nut and mechanical. The nut surface is rough and irregular, so the contact area cannot be modeled as regular shape. How to set up contact constraint model is the key problem to accomplish non-loss shelling. In order to study the shell-breaking mechanism and structural design of the nut shelling manipulation, a multi-fingered metamorphic manipulator is presented. An overview of the nut shelling technology and the contact manipulator modeling are proposed. The origin and application of metamorphic mechanisms are introduced. Then the research contents and development prospects of nut shelling manipulator are described.

    • Research on balancing problem and planning methods for mixed model assembly line

      2017, 38(2):116-122. DOI: 10.7535/hbkd.2017yx02003

      Abstract (2657) HTML (0) PDF 1.23 M (2080) Comment (0) Favorites

      Abstract:Aiming at the balancing/rebalancing problem of mixed-model assembly line(MMAL) caused by customer demand changes, product design development and assembly technology and equipment upgrades, the contents and research progress of MMAL are summarized. Firstly, the research progress and the planning methods are described in the balancing and rebalancing of MMAL. Then, the classification and general solution for MMAL balancing problems are summarized. Finally, this paper puts forwards the future research consideration on the balancing of MMAL.

    • >Mathematics
    • Classification of 4-dimensional associative algebras with principal generators over complex numbers

      2017, 38(2):123-130. DOI: 10.7535/hbkd.2017yx02002

      Abstract (1949) HTML (0) PDF 756.38 K (2284) Comment (0) Favorites

      Abstract:In order to obtain the classification of 4-dimensional associative algebras with principal generators over complex number C under isostructuralism, by using the ring theory and distribution of roots of the equations satisfied by the principal generators: one quadruple root, four different roots, one triple root and one simple root, two different double roots, one double root and two different simple roots, the above equations are translated and stretched, then the more simple equations are obtained. By using linear algebras, quotient algebras and maple to make a large number of operations, it is concluded that each isomorphism type has nothing to do with parameters. Finally by comparing each isomorphism type, the complete classification is obtained, which deepens the realization of structure of asso ciative algebra, and provides reference for relative study.

    • Existence of positive solutions to a class of elastic beam equations

      2017, 38(2):131-136. DOI: 10.7535/hbkd.2017yx02005

      Abstract (2103) HTML (0) PDF 583.71 K (1304) Comment (0) Favorites

      Abstract:Elastic beam is a kind of mathematical model in elastic mechanics and engineering physics. For now, this type of model is often used in real life. On the basis of the relative research on the elastic beam equations with one end fixed and one end sliding support, and the multiple solutions of the elastic beam equation are researched. In this paper, through putting this problem into an integral equation, which is equivalent to an operator fixed-point problem, and combining with the properties of Green function and Guo- Krasnoselskii fixed point theorem of cone expansion and compression, the existence of positive solutions of this kind of elastic beam equations is discussed. Under various assumptions on nonlinear terms, the intervals of the parameters are established, and the existence of one positive solution, two positive solutions or nonexistence of positive solutions for this elastic beam equations are obtained. In conclusion, the intervals of eigenvalue about this problem for at least one positive solution, two positive solutions and nonexistence of positive solutions are obtained. The study of the existence of such solution can not only contribute to the stability analysis of elastic beams, but also enrich the theory of material mechanics.

    • Asymptotic behavior for cross coupled parabolic equations

      2017, 38(2):137-142. DOI: 10.7535/hbkd.2017yx02006

      Abstract (2049) HTML (0) PDF 613.28 K (1267) Comment (0) Favorites

      Abstract:In order to better describe the heat transfer process of three kinds of mixed substances, namely the reaction of the reactants in the three chemical reactions, a class of three variable cross coupling with non parabolic equations of the whole existence of local source and non local boundary flow and the finite time blow up problem with breaking method for the solution of the first commonly used feature value structure are studied. The structure of the equations of the upper and lower solutions by using the method of ordinary differential equation reference is broken, with comparison theorem, the proof shows that obtained by local source power function and exponential function of parabolic equations is broken, with the sufficient conditions for global existence of clegerate purubolic equations solutions cross coupled by local source power function and non local sources exponential function are proved, as soon as the solution of blowing up in finite time degradation of non local sources of cross coupling, providing better support for the theory of heat transfer and chemical reaction problem.

    • Research about the number of D-points of -tiling in given ellipse

      2017, 38(2):143-150. DOI: 10.7535/hbkd.2017yx02007

      Abstract (2286) HTML (0) PDF 928.46 K (2252) Comment (0) Favorites

      Abstract:An Archimedean tiling is a tiling of the plane by one type of regular polygon or several types of regular polygons, and every vertex of the tiling has the same vertex characteristics. There are 11 Archimedean tiling, and this paper studies -tiling, which is an Archimedean tiling generated by squares and regular octagons in the plane, and every vertex is associated with one square and two octagons. This paper studies the number of vertices contained in an ellipse in -tiling. Through analysing the sequence of vertices lying on half chord in the ellipse, and using the method of the geometry of number and congruence in number theory, it presents an algorithm about the value of the number of vertices contained in the ellipse, and obtains a formula of limit about the number of vertices and the square of short semi-axis of the ellipse. It is proved that the value of limit is connected with the area of the corresponding central polygon. The algorithm and the formula of limit are very useful for the study of related problems in other Archimedean tilings.

    • >Physics
    • Influence of disorder and magnetic field on conductance of “sandwich” type two dimensional system

      2017, 38(2):151-157. DOI: 10.7535/hbkd.2017yx02008

      Abstract (2021) HTML (0) PDF 759.92 K (2262) Comment (0) Favorites

      Abstract:In order to discuss the transport phenomena and the physical properties of the doping of the disorder system under magnetic field, the electron transport in a two-dimensional system is studied by using Green function and scattering matrix theory. Base on the two-dimensional lattice model, the phenomenon of quantized conductance of the "sandwich" type electronic system is analyzed. The contact between the lead and the scatterer reduce the system's conductance, and whittle down the quantum conductance stair-stepping phenomenon; when an external magnetic field acts on to the system, the conductance presents a periodicity oscillation with the magnetic field. The intensity of this oscillation is related to the energy of the electron;with the increase of the impurity concentration, the conductance decreases.In some special doping concentration, the conductance of the system can reach the ideal step value corresponding to some special electron energy. The result could provide reference for further study of the conductance of the "sandwich" type two dimensional system.

    • >Chemistry and Chemical Industry
    • Content determination of obeticholic acid tablets by HPLC

      2017, 38(2):158-162. DOI: 10.7535/hbkd.2017yx02009

      Abstract (3155) HTML (0) PDF 685.74 K (3258) Comment (0) Favorites

      Abstract:In order to establish a method for the content determination of obeticholic acid tablets, HPLC-UV method is adopted. The determination is performed on Agilent HC-C18 column(250 mm×4.6 mm,5 μm) with mobile phase acetonitrile (002% formic acid)-water (0.02% formic acid) = 60∶40 (V/V) at the flow rate of 1.0 mL/min. The detection wavelength is 195 nm, the column temperature is 30 ℃ and the volume is 100 μL. The result shows that there is a good liner relationship between the mass concentration of obeticholic acid in the range of 0.200 26~1.001 30 mg/mL and the peak area, and r=0.999 9. The RSD of precision, stability and reproducible tests are all less than 1.0%. The average recovery rate is 99.64% , and RSD is 0.58%(n=9). The method is simple, exclusive, accurate and durable, and can be used for the content determination of obeticholic acid tablets.

    • Study of the electrochemical behaviors of ion-binding to calmodulin

      2017, 38(2):163-168. DOI: 10.7535/hbkd.2017yx02010

      Abstract (1861) HTML (0) PDF 746.55 K (2172) Comment (0) Favorites

      Abstract:In order to research the competitive binding with CaM between metal ions and Ca2+, electrochemical impedance spectroscopy (EIS) of ion (such as Ca2+,Cd2+,Al3+,Fe3+) -loaded CaM self-assembled membrane on Au electrode in 0.15 mol/L NaCl solution containing 2 mmol/L sub>]3-/4- at pH 6.5 is investigated. The results indicate that the ion-binding property of CaM can be detected by the change of the electrochemical reaction resistance. Ca2+,Cd2+ and Al3+ can combine with CaM,and Fe3+ can’t combine with CaM. The binding ability of Ca2+ to CaM is stronger than that of Al3+. Ca2+ binding site of CaM is different from that of Al3+ and same as that of Cd2+. Electrochemical impedance spectroscopy provides a new method for the research of metal ions and CaM competition binding.

    • >Mechanical, Electronics and Information Science
    • Evaluation of the CoDA community detection algorithm based on directed network

      2017, 38(2):169-175. DOI: 10.7535/hbkd.2017yx02011

      Abstract (2723) HTML (0) PDF 907.67 K (2327) Comment (0) Favorites

      Abstract:CoDA (Communities through Directed Affiliations) algorithm is a kind of community detection algorithm which can successfully detect 2-mode communities based on probability model. The F-measure criterion, for information retrieval, is adapted to the evaluation of CoDA algorithm in directed networks with overlapping communities or non-overlapping communities. The value of F1-measure in F-measure criterion can reflect whether CoDA algorithm performs well or not. The data sets used in the experiment is generated by the LFR Benchmark tool. The minimum number of nodes in data set is 100 and the maximum is 20 000, and evaluated experiment is conducted when every 100 nodes is added. The results show that CoDA algorithm performs well when the number of nodes is bellow 1 600. CoDA algorithm's performance becomes worse with the increase of the number of nodes, which proves the CoDA algorithm based on probability model is applicable to the community detection of small-scale networks.

    • Research of PMSM-DTC system based on the super-twisting second sliding mode control

      2017, 38(2):176-182. DOI: 10.7535/hbkd.2017yx02012

      Abstract (3006) HTML (0) PDF 830.22 K (2178) Comment (0) Favorites

      Abstract:Aiming at the problems that the conventional permanent magnet synchronous motor direct torque control system (PMSM-DTC) is susceptible to the influence of parameter change and torque ripple, it is proposed that the space voltage vector modulation technique (SVPWM) is used instead of the traditional sinusoidal pulse width modulation (SPWM), on the basis of which the second-order sliding mode variable structure control rate with super-twising algorithm is introduced, with the stator flux linkage and torque as the controlled object to design the controller instead of traditional PI controller in the system. The simulation results show that the strategy not only eliminates effectively the first-order sliding mode chattering problems, significantly reducing the stator flux linkage and torque ripple, but also has strong ability of speed tracking, with robustness to load disturbance, and parameter changes, etc., therefore can be well applied in motor control.

    • Research of Tai-chi-chuan auxiliary training system based on Kinect

      2017, 38(2):183-189. DOI: 10.7535/hbkd.2017yx02013

      Abstract (2838) HTML (0) PDF 1.12 M (2584) Comment (0) Favorites

      Abstract:In order to promote the scientific standardization of Tai-chi-chuan teaching and training, a Tai-chi-chuan auxiliary training system based on Kinect motion capture technology and extraction of the angle feature and speed feature is proposed and designed. The dynamic time planning algorithm (DTW) sampling corresponding frame is applied to replace the traditional method of sampling the key frame. The auxiliary training system consists of learning module, action acquisition module and action scoring module. Learning module with stan-dard action teaching video, to meet the requirements of students learning; action acquisition module uses Microsoft developed Kinect equipment to realize data acquisition of the spatial coordinates of the human skeleton in Tai-chi-chuan action, and through filtered noise reduction and the occlusion point data processing the skeleton data is saved. The scoring module constructs the test sequence based on the 16 angle features of eight key joint nodes and the instantaneous velocity characteristics of 20 joint nodes. By comparing with the standard sequence in real time, the original scoring rules is used to achieve the scoring function, which provides students with intuitive and reliable training recommendations, so as to improve the efficiency of learning. By increasing the number of sensors, further designing and optimizing data fusion and filtering algorithm, combining with Microsoft’s Kinect2.0 version, the system can also be applied to medical rehabilitation, physical training analysis and evaluation, virtual reality and human-computer interaction, etc.

    • Kinematics analysis and simulation of a new underactuated parallel robot

      2017, 38(2):190-195. DOI: 10.7535/hbkd.2017yx02014

      Abstract (2371) HTML (0) PDF 789.83 K (2549) Comment (0) Favorites

      Abstract:The number of degrees of freedom is equal to the number of the traditional robot driving motors, which causes defects such as low efficiency. To overcome that problem, based on the traditional parallel robot, a new underactuated parallel robot is presented. The structure characteristics and working principles of the underactuated parallel robot are analyzed. The forward and inverse solutions are derived by way of space analytic geometry and vector algebra. The kinematics model is established, and MATLAB is implied to verify the accuracy of forward and inverse solutions and identify the optimal work space. The simulation results show that the robot can realize the function of robot switch with three or four degrees of freedom when the number of driving motors is three, improving the efficiency of robot grasping, with the characteristics of large working space, high speed operation, high positioning accuracy, low manufacturing cost and so on, and it will have a wide range of industrial applications.

    • >Food Science and Biological Science
    • Structure, function and latest research development of collagen of type Ⅱ

      2017, 38(2):202-208. DOI: 10.7535/hbkd.2017yx02016

      Abstract (3399) HTML (0) PDF 1.08 M (2211) Comment (0) Favorites

      Abstract:Collagen of type Ⅱ is the major component of hyaline cartilage in animals. Based on its biocompatibility, biodegradability and many other biological properties, for example promoting cell growth and differentiation, collagen of type Ⅱ has been widely applied in various fields, such as tissue engineering material, food, cosmetic, packaging, etc.. In recent years, using genetic engineering to produce recombinant collagen of type Ⅱ is popular. The structure, function and application of collagen of type Ⅱ are described, the latest research progress for producing recombinant collagen of type Ⅱ by genetic engineering is put forward, and the large-scale production of hydroxylated collagen in E.coli in the future is previewed, which would be helpful for the further development and study of collagen of type Ⅱ.

    • >Material Science
    • Influence of process parameters on the uniformity of microstructure of semi-solid casting-forging 7075 alloy

      2017, 38(2):196-201. DOI: 10.7535/hbkd.2017yx02015

      Abstract (2215) HTML (0) PDF 1.13 M (2058) Comment (0) Favorites

      Abstract:Liquid phase segregation frequently occurs in the process of semi-solid die forging, which makes the parts appear “weak point” or “weak region”, and usually, the “weak point” or “weak area” is the reason of crack and service condition failure. In order to analyze the influencing factors for the liquid phase segregation of the semi-solid die forging, in this paper, the sample of semi-solid 7075 alloy is prepared by hand stirring method. The casting-forging forming of the sample is made by means of press machine and cup mould to research the influence of alloy temperature, head preheating temperature, hold time and other process parameters on the uniformity of the microstructure. The results show that the semi-solid casting-forging process is feasible within a set of mold. Under the conditions of head temperature of 400 ℃, hold time of 2 s and the forming pressure of 50 MPa, the liquid phase segregation degree of cup sample increases, the uniformity of the microstructure becomes worse with increasing of alloy temperature. The segregation degree is up to 14.02% when the alloy temperature is 628 ℃. The liquid phase segregation degree of cup sample decreases and uniformity of the microstructure becomes better along with increasing of head preheating temperature. Under the conditions of alloy temperature of 621 ℃, the forming pressure of 50 MPa, and head preheating temperature of 400 ℃, the liquid phase segregation degree of cup sample decreases, the uniformity of the microstructure becomes better along with increasing of the hold time. The segregation degree is up to 2.99% when the hold time is 4 s. The results could provide theoretical reference for the process formulation and experimental research of aluminum alloy semi-solid casting-forging forming.

Editor in chief:朱立光


International standard number:ISSN 1008-1542

Unified domestic issue:CN 13-1225/TS

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