• Issue 3,2018 Table of Contents
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    • >Special Column: National Young Scholar/Local Science Foundation
    • Analysis of lubricant retention property and tribological property of C/SiC composite material

      2018, 39(3):191-197.

      Abstract (1715) HTML (0) PDF 1.93 M (2195) Comment (0) Favorites

      Abstract:Composite materials have attracted more and more attention because of their special properties. However, the tribological properties of the composite material still need further study because of their complex structure and many influencing factors. In order to compare the influence of friction pair on the tribological property and lubricant retention property of C/SiC composite material, the tribological properties of C/SiC composite material sliding against 45# steel and ZrO2 are studied based on pin on disc test method. The wear surface of C/SiC composite material is characterized by 3D profiler. The lubricant retention property is investigated based on the 3D surface topography. The result shows that C/SiC composite material wears heavily when sliding against 45# steel and the lubricant retention properties decreases dramatically. C/SiC composite material exhibits low friction coefficient and wear when sliding against ZrO2 material, and the wear surface has good load-carrying property and lubricant retention property, which indicates that C/SiC composite material and ZrO2 are good friction pair. The research result provides strong support to boarding the application and revealing the tribological properties of C/SiC composite material.

    • Survey on the hunting stability of High-speed Trains

      2018, 39(3):198-203. DOI: 10.7535/hbkd.2018yx03001

      Abstract (1897) HTML (0) PDF 2.36 M (2791) Comment (0) Favorites

      Abstract:The long-term service safety and reliability of high-speed trains are the primary guarantee for the construction of high-speed trains. Self-excited hunting movement is a unique form of instability for rail vehicles. In order to guarantee the hunting stability, high speed and safety traffic of high speed trains, on the basis of the theoretical research methods of high speed train hunting unstability, the main research methods and their deficiency are summarized, as well as the recent research hotspots. The research of non-smooth bifurcation and asymmetric operation stability is prospected. Without considering the nonlinear characteristics of the vehicle, the characteristic root method, the routh-hurwitz criterion method and the minimum damping coefficient can be used to analyze the certainty stability of high speed trains. When the wheel-rail contact and the nonlinear characteristics of the suspension system must be considered, the method of eigenvalue change, QR algorithm, binary method, center manifold method, shooting method and continuation algorithm can be used. In addition, stochastic nonlinear dynamics hamilton theory, monte-carlo method, semi-implicit milstein stochastic numerical simulation and small data quantity can be used to analyze random stability, random bifurcation and its types. Generally speaking, stochastic stability and random bifurcation can get closer to the real conditions of the critical speed of instability because of considering their own structure parametric excitation and wheeltrack contact irregularity excitation. This aspect of theoretical research and experimental research has been paid more attention to by researchers, and has become a hot topic of the hunting stability of high speed trains.

    • Research progress on visual perception and end-effecter of undamaged operation for fruit-picking robot

      2018, 39(3):204-213. DOI: 10.7535/hbkd.2018yx03003

      Abstract (1670) HTML (0) PDF 4.47 M (2521) Comment (0) Favorites

      Abstract:Research and development of fruit-picking robot is of great significance for improving harvest efficiency, guaranteeing fruit quality and reducing labor intensity. However, picking-robot under the effect of non-structural factors including over lapping, adhesion and occlusion between bunched fruits may damage the fruits very easily due to inaccurate target positioning, incorrect clamping-cutting sequence and improper clamping-cutting gesture. The main cause of the damage is that the coupling mechanism between visual cognition and clamping-cutting actuators for undamaged picking has not been well settled. In order to comb the latest research progress on anti damage operation of fruit-picking robot, this paper makes a comprehensive review and analysis on undamaged harvesting from three aspects: the multi-dimensional information of targets by visual perception, such as picking point, peduncle position, bounding volume of grape for undamaged fruit-picking and so on; visual cognition and intelligent anti damage picking planning of fruit-picking robots; anti damage picking mechanism design and its behavior control. Moreover, the key problems that need to be solved in the future are summarized and prospected. This paper may provide reference and views for further research on the problems of fruit intelligent undamaged picking in unstructured environment.

    • Dynamic analysis of dry friction system based on improved bilinear hysteretic model

      2018, 39(3):214-220. DOI: 10.7535/hbkd.2018yx03004

      Abstract (1508) HTML (0) PDF 2.35 M (2198) Comment (0) Favorites

      Abstract:Considering that the dry friction force only shows stiffness characteristic when the normal contact force is high and combining with the existing conclusions of experimental research, the bilinear hysteresis model is improved. Runge kutta method is adapted to calculate the dynamic response of the dry friction damping system, the nonlinear characteristics of the system are analyzed by means of Fourier transform, Poincare diagram and phase diagram. Simulation results show that the system has no bifurcation and chaotic phenomenon when separation of dry friction contact is not considered, steady-state response and the friction force don't have sub-harmonic response and higher harmonic component is very small, which proves that using the equivalent linearization method which is based on the first order harmonic balance method to solve the dry friction damping system is accurate when separation is not considered; vibration reduction effect of the contact stiffness, excitation amplitude and normal load of dry friction damping system is obtained, and it is almost consistent with the related test results. The relevant conclusions can provide references for the design of dry friction damper in engineering.

    • Research progress and development prospect of Nepenthes pitcher in engineering bionics field

      2018, 39(3):221-231. DOI: 10.7535/hbkd.2018yx03005

      Abstract (1630) HTML (0) PDF 2.68 M (2664) Comment (0) Favorites

      Abstract: Nepenthes pitcher has evolved particular structures to effectively capture and digest insects to obtain sufficient growing nutrients. The pitcher can be typically distinguished by several parts depending on its difference in macro-morphology and micro-structure, including lid, peristome, slippery zone and digestive zone. The peristome consists of radial ridges, making liquid film generate a continuously unidirectional transport. The slippery zone contains structures with micro-nano scale parameters, presenting the properties of anti-attachment and superhydrophobicity. The structures and properties of the pitcher have attracted numerous studies and become the hot topic. In this review, based on the research progress of peristome and slippery zone in the engineering bionic field, the morphological structures and functional properties are introduced. Especially, the progress of the bionic fabrication of functional surfaces used in liquid film unidirectional transport, insect slippery trapping and superhydrophobicity is dis cussed, and several aspects that should be paid attention to in near future are highlighted. This review enriches the understanding of structures and properties of Nepenthes pitcher, and also provides the bionic ideas for fabricating functional surfaces.

    • Research on reclamation methods and equipments of used waterglass sand

      2018, 39(3):232-237. DOI: 10.7535/hbkd.2018yx03006

      Abstract (1555) HTML (0) PDF 1.57 M (2379) Comment (0) Favorites

      Abstract:Waterglass sand is used widely in the field of green casting, however, the problem of used sand reclamation puzzles the workers of foundry and environmental protection for a long time. Aiming at this problem, domestic and foreign scholars mainly put forward dry reclamation, wet reclamation, heat dry reclamation, chemical reclamation, biological reclamation and other waterglass reclamation methods. In this paper, several typical waterglass reclamation method principle and equipment are described in detail. Advantages and disadvantages of different reclamation methods are analyzed. A series of used waterglass sand reclamation equipments developed by our group are introduced. Meanwhile, it is considered that the biological reclamation of the future used waterglass sand will focus on the green and efficient used waterglass sand promoting solvent and the development of the reclamation equipment.

    • >Physics
    • Research on a special pendulum

      2018, 39(3):238-242. DOI: 10.7535/hbkd.2018yx03007

      Abstract (1816) HTML (0) PDF 1.67 M (1492) Comment (0) Favorites

      Abstract:In order to solve the problem of unstable swinging amplitudes of the crane's boom and supporting points for moving heavy objects in the transportation and industrial industries, a pendulum system model with circular motion in the horizontal plane is used to simulate the dynamic process of this problem. The differential equations of the pendulum ball are deduced using the Lagrange equation, and the numerical solution is obtained using the fourth-order Runge-Kutta algorithm. The suspension angles are obtained for the pendulum to make a stable circular motion under the designated conditions of the radius, frequency, and pendulum length of the suspension point. The stable trajectory of the pendulum ball is calculated, and the calculation results are compared with the experimental results. The theoretical calculations and the experimental results are in good agreement. The research content of this paper has a wide range of applications in scientific research and engineering technology. The research results have important reference value for the crane's mechanical jib design. At the same time, the theoretical modeling, computer programming, numerical calculation, and experimental design used in this paper can also be used as a very good teaching case to cultivate students' ability to apply the learned theory to solve practical problems.

    • >Special Column: New Energy Resources, Energy Conservation and Environmental Protection
    • Novel deprotection method of Fmoc group using nano-K2CO3

      2018, 39(3):243-248. DOI: 10.7535/hbkd.2018yx03008

      Abstract (2527) HTML (0) PDF 1.24 M (2267) Comment (0) Favorites

      Abstract:Fmoc is usually used as an amino-protecting group. The traditional removal method is realized by using a secondary amine. However, this method has some shortcomings including high cost, difficult recycle of excess secondary amine and environmental pollution. The paper reports a novel heterogeneous deprotection method of Fmoc group using a new inorganic base, namely, nano-potassium carbonate. Nano-potassium carbonate with average particle size 64 nm is prepared using wet grinding method. The deprotection of Fmoc-Phe-OBn is preformed as a Model reaction. The optimum conditions are that reaction solvent is absolute ethanol, molar ratio of Fmoc-L-Phe-OBn to nano-K2CO3 is 1︰2, and reaction temperature is 25 ℃. The corresponding free amino compound is obtained with high yield. To further explore the scope and limitations of this method, seven substrates including Fmoc- anmino acids and dipeptides are examined. All the yields are above 98%. The nano-K2CO3 could be regenarated and reused for 5 times without loss of its reactive activity. This method has the advantages of simple operation, low cost, small pollution and recyclable potassium carbonate,and has important reference value for the research on the synthesis and deprotection of polypeptides.

    • Optimization of the photovoltaic performance of ZnO-based organic-inorganic hybrid solar cells

      2018, 39(3):249-260. DOI: 10.7535/hbkd.2018yx03009

      Abstract (1579) HTML (0) PDF 3.19 M (1931) Comment (0) Favorites

      Abstract:Organic-inorganic hybrid solar cell is a new type of solar cell, with its organic polymers to provide electrons and inorganic semiconductors to accept electrons. The commonly used inorganic semiconductors are nano-sized zinc oxide (ZnO), titanium dioxide (TiO2), cadmium sulfide (CdS), etc. There are many problems needing to be solved in the research process of hybrid solar cells, such as the poor electron transport efficiency, low utilization of solar energy, chemical incompatibility between inorganic semiconductors and organic polymers, and the consequently caused low photoelectric conversion efficiency. Around the above issues, concerning the solar cell with the ZnO semiconductors as electron acceptor, the photovoltaic performance optimization methods are discussed from the aspects of electron acceptors, electron donor materials and the addition of modified layers for the ZnO-based solar cell, and the future development tendency of the hybrid solar cells is also prospected. The optimization of cell performance has brought hope to the low cost and high efficiency application of this hybrid solar cell.

    • >Mechanical, Electronics and Information Science
    • Numerical simulation of cooling heat transfer of supercritical carbon dioxide in twisted elliptical tubes

      2018, 39(3):261-267. DOI: 10.7535/hbkd.2018yx03010

      Abstract (1486) HTML (0) PDF 1.88 M (1545) Comment (0) Favorites

      Abstract:In order to enhance the heat transfer performance of CO2 heat pump, based on the numerical simulation method of Fluent, the law of supercritical CO2 cooling and heat transfer characteristics and secondary flow in the horizontal elliptical tube whose torque is 100 mm or one infinity number under different mass flow are studied. In addition, concerning part coefficient of heat transfer and pressure drop brought by vertical elliptical tube, the influence of the length of the axial ratio b/a and the torque on the heat transfer performance is studied. Simulation results show that, the effect of buoyancy on the twisted elliptical tube is significantly larger than that of elliptical tube under low mass flow, and for the elliptical tube when supercritical CO2 is under the low mass flow G<200 kg/(m2·s2), the elliptical tube has a greater intensity of secondary flow caused by buoyancy, and the enhanced heat transfer is more pronounced; when supercritical CO2 is under the high mass flow G>200 kg/(m2·s2) , the twisted elliptical tube has a greater intensity of periodic secondary flow caused by self-structure, and the enhanced heat transfer is more pronounced; the heat transfer coefficient and pressure drop increase with the increasing degree of twist and flattening. It provides important theory and data support for the application of the twisted elliptical tube in CO2 heat pump.

    • Center-point coordinate vision automatic extraction method for row billet end face

      2018, 39(3):268-274. DOI: 10.7535/hbkd.2018yx03011

      Abstract (1594) HTML (0) PDF 1.36 M (1799) Comment (0) Favorites

      Abstract:In order to realize rapid extraction of the center coordinates for row billet end faces when labeled by multi-strand billet end face labeling robot, a research program is proposed that the image coordinates in billet end face image are extracted and then the center point's coordinates of the billets end face image are calculated. Firstly, an improved SUSAN corner detection algorithm is proposed to solve the corner leak detection problem caused by the distance between the adjacent billet image edge being too small and the billet image corner angle being the arc angle. Then, the image plane coordinates of corners point are extracted, and the number of the billets end faces image in each enclosed area is calculated. Finally, a method for extracting the coordinates of slant billet end faces is provided, and the center point image plane coordinates of each billet end face are calculated, respectively. The robot labeling experiment of each billet end face in a row billet is carried out, and experimental results indicate that the horizontal and vertical labeling position error ranges of each billet end face are -0.625~0.850 mm and -0.550~0.875 mm, respectively, meeting the enterprises' allowed center coordinates position error value 1 mm of the billet end face fully. The visual methods mentioned in this paper are feasible in both theoretical and practical applications, and it not only provides an accurate labeling position for the continuous blank end labeling robot, but also provides a reliable method for extracting the center coordinates of rectangular image elements, and has some application value.

    • Evolutionary algorithm design based on evolutionary efficiency factor

      2018, 39(3):275-281. DOI: 10.7535/hbkd.2018yx03012

      Abstract (1592) HTML (0) PDF 1.17 M (1983) Comment (0) Favorites

      Abstract:With the development of electronic chip technology, circuit systems become gradually high integrated and intelligent. Under the interface of complex electromagnetic field environment, the requirements for the stability and reliability of information electronic system are getting more and more urgent. The autonomous fault-tolerant capability and reliability of the circuit system are faced with new challenges in circuit design. In order to improve the anti-interference ability of circuit under bad conditions, the obtained evolutionary efficiency factor after analyses is taken as the influence factor of the algorithm, and it is introduced into the fitness function of the algorithm to improve the algorithm. The research result show that for the single point short circuit and open circuit fault simulation experiments, the average fault-free probabilities of the evolutionary algorithm based on evolutionary efficiency factor are 0.754 and 0.853, respectively; compared with the traditional evolutionary algorithm, the two probabilities increase by 16.4% and 14%, respectively; compared with the adaptive algorithm, the two probabilities increase by 6.7% and 5%, respectively. It is proved that the introduction of evolution efficiency factor can improve the robustness and fault-tolerance ability of the circuit system under the effect of interference or local damage. The research result may provide reference for the reinforcement and optimization of the improved circuit design.

    • Research on intelligent phone number checking engine based on text similarity

      2018, 39(3):282-288. DOI: 10.7535/hbkd.2018yx03013

      Abstract (1515) HTML (0) PDF 1.04 M (1725) Comment (0) Favorites

      Abstract:In order to help the telephone customer service agents provide uninterrupted and stable quality services, it is necessary to develop the intelligent phone number checking engine. Based on the research of the longest common subsequence algorithm and the longest common sub-element sequence algorithm, a short text similarity calculation algorithm is proposed to improve the accuracy of the search number. Based on this, the intelligent phone number checking engine and its implementation method are designed. Taking into account the actual needs, the data is preprocessed by word segmentation, abbreviation substitution, synonym replacement, and construction of stopword vocabularies in natural language processing; further data processing is accomplished by similar calculations based on HowNet and synonym word forests. Externally API interfaces abiding by REST-compliant are provided. Experiments show that the design of the intelligent phone number checking engine is feasible and has good business processing capabilities to meet user needs. At the same time, there are also some problems that need further improvement. The intelligent phone number checking engine can provide 24 hours uninterrupted service. Compared with manual services, it has higher search efficiency and more stable quality services, which can provide reference for the development of smart phone customer service.

Editor in chief:朱立光

Inauguration:

International standard number:ISSN 1008-1542

Unified domestic issue:CN 13-1225/TS

Domestic postal code:

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