• Issue 5,2018 Table of Contents
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    • >Special Column: National Young Scholar/Local Science Foundation
    • Research summary of the usability of CNC machine tools

      2018, 39(5):379-385. DOI: 10.7535/hbkd.2018yx05001

      Abstract (1468) HTML (0) PDF 1.04 M (2168) Comment (0) Favorites

      Abstract:The usability of CNC machine tools is a comprehensive reflection of reliability, maintainability and supportability, which is also a feature that users concern about mostly. It is affected not only by the function failures of CNC machine tools, but also by the performance failures, such as precision degradation, performance fluctuation, oil leakage and so on. So separated research on reliability is not enough to maintain the "usable and easy-to-use state" of domestic CNC machine tools. The present situation and research significance of domestic CNC machine tools' usability are analyzed. The research status of usability modeling method and maintenance decision method at home and abroad are expounded. Then the problems and developments existing in usability research of CNC machine tools are summarized. Finally, the understanding of two key scientific problems in urgent need of research are put forward, including systematic modeling for the usability based on meta-action unit and active maintenance decision centered on usability of CNC machine tools, which might provide ideas for the usability research of CNC machine tools.

    • Review on the key techniques of the variable-fidelity approximation based design optimization

      2018, 39(5):386-393. DOI: 10.7535/hbkd.2018yx05002

      Abstract (1641) HTML (0) PDF 1.67 M (2204) Comment (0) Favorites

      Abstract:Using the variable fidelity approximation model based design optimization can take full use of the advantages and characters of analysis models of different fidelity levels, greatly reducing the giant computed amount during complicated engineering products design process, improving computational efficiency, and making it become an effective way to solve the important problem of how to improve the computational efficiency as greatly as possible. The basic idea of variable-fidelity approximation based design optimization is introduced. Its relevant research contents and key technologies are summarized. Researches about the design of experiments for variable-fidelity approximation, the variable-fidelity approximation modeling and optimization strategy are reviewed. Finally, some principal aspects needed to be improved in future are present, including the sequential sampling for variable-fidelity approximation, Cokriging, space mappling based variable-fidelity approximation, and the application of the variable fidelity approximation model in multidisciplinary design optimization and uncertainty optimization.

    • Research on the method of mass estimation for heavy vehicles

      2018, 39(5):394-400. DOI: 10.7535/hbkd.2018yx05003

      Abstract (1697) HTML (0) PDF 2.14 M (2067) Comment (0) Favorites

      Abstract:To solve the vehicle mass estimation problems, two vehicle mass estimation methods based on both commonly used dynamics method and kinematic method are analyzed by simulation and experimental study. The principles of two vehicle mass estimation methods are described. Then a model is built on the TruckSim software platform and the simulation analysis is carried out taking into account these two methods in multi conditions. Some vehicle experiments are carried out based on the simulation results. A method of vehicle speed redundancy calculation and acceleration calculation are proposed, and the real time vehicle mass is estimated by using the recursive least squares (RLS) with time varying forgetting factor. The research results demonstrate that the speed redundancy calculation method and acceleration calculation method are effective and accurate. And the convergence speed of the algorithm can be significantly improved by reducing shifts. It is concluded that, compared with the kinematic estimation algorithm, the proposed longitudinal dynamic estimation algorithm can estimate vehicle mass effectively with better robustness, more accuracy and faster convergence, and its engineering application is valuable.

    • Study on vibration characteristics of wind turbines under different wind speeds

      2018, 39(5):401-408. DOI: 10.7535/hbkd.2018yx05004

      Abstract (1495) HTML (0) PDF 2.20 M (2308) Comment (0) Favorites

      Abstract:When the wind turbine blades are running under normal conditions, the blades will vibrate due to periodic aerodynamic forces, and the use time of blades will be reduced. In order to study the vibration characteristics of wind turbine blades, this paper selects 5 operating conditions (wind speed range from 15 m/s to 40 m/s) under different wind speed conditions. The CFD method is used to simulate the NREL PHASE VI blade, and the vibration and vibration displacement curves under different wind speeds are obtained. The results show that: 1) the main vibration modes of the blade are waving and shimmy, and the high order blade vibration modes have complex deformation of bending and torsion. 2) When the inlet velocity increases from 15 m/s to 40 m/s, the uneven distribution of pressure distribution on suction surface is increasing, and the maximum pressure difference is about 3 000 Pa when the inlet velocity is 40 m/s. 3) when the flow velocity is 15 m/s, the minimum amplitude is 0.525 4 mm, and when the flow velocity is 40 m/s, the vibration reaches the maximum of 3.628 2 mm, which is about 6.9 times of the minimum amplitude. The vibration curves of the 5 operating conditions are all attenuated trend and the blades tend to stabilize vibration, and when the wind speed is larger, the aerodynamic force generated by the wind flow has a greater force on the blade, and the amplitude of the blade tends to increase. The results of this study can provide a reference for the design of wind turbines.

    • >Physics
    • Acoustic propagation properties of triangle array metamaterials

      2018, 39(5):409-415. DOI: 10.7535/hbkd.2018yx05005

      Abstract (1695) HTML (0) PDF 3.18 M (1750) Comment (0) Favorites

      Abstract:To make acoustic wave produce abnormal transmission characteristics which are different from traditional natural acoustic materials, COMSOL finite element method is used to simulate the propagation characteristics of acoustic wave in local resonant phonon crystals.The vibration mechanism of 2D three-component locally resonant phononic crystals is given, and the acoustic metamaterials model of triangular array is constructed on the basis of cellular, to explore the local resonance characteristics between acoustic waves and cellular within the model. The simulation results show that the planar point and linear excitation source which is incident from the bottom edge of the triangular array model would be refocused at the top angle after being regulated by the model; the low-loss moving effect of point source could be achieved by incident rectangular model composed of triangular array; when two or three identical triangular arrays are combined into a parallelogram and a trapezoid model, the plane sound waves would be transformed to transmit. The simulation results show that this kind of triangle-based acoustic metamaterial array model will produce abnormal acoustic phenomenon under the resonance frequency, and the resonance characteristics will also change with the change of model construction, resulting in different abnormal acoustic phenomenon. The results can provide new ideas for acoustic stealth, acoustic detection and directional transmission with low acoustic loss.

    • >Chemistry and Chemical Industry
    • Synthesis, crystal structure, and thermal stability of a sulfate-bridged Zn(Ⅱ) polymer with

      2018, 39(5):416-421. DOI: 10.7535/hbkd.2018yx05006

      Abstract (1494) HTML (0) PDF 2.25 M (1622) Comment (0) Favorites

      Abstract:In order to further study the coordination reaction rules and properties of organic ligands containing benzimidazole with Zn(Ⅱ), a new one-dimensional coordination polymer {[Zn(AMBI)(H2O)SO4]·0.5H2O}<sub>n has been synthesized by the reaction of zinc(Ⅱ) sulfate heptahydrate with the bidentate ligand 2-aminomethyl-1H-benzimidazole (AMBI) and characterized by elemental analysis, IR, UV spectrum, TG and single-crystal X-ray diffraction. The thermal stability is studied. X-ray single-crystal structure analysis shows that the colorless block crystal of the title complex belongs to monoclinic system, space group C2/c. In the complex, the Zn(Ⅱ) is coordinated by two N atoms from one AMBI ligand, two O atoms from SO2-4 ion and one O atom from water in a distorted square pyramidal coordination geometry. The structure of the title complex exhibits an infinite chain-like structure through bridging SO2-4 anion. The hydrogen-bonding and π…π interactions extend the complex into quasi 3D networks. Through the structure study on the supra-molecular complex, it′s further understood about how the structure of the ligand and non-covalent interactions, such as hydrogen bonding and π…π stacking, influence the topological structures of supra-molecular compounds. This study has important reference value for rational selection of organic ligands and synthesis of coordination polymers with novel structures.

    • Research of the synthesis of the hemicellulose-g-AA/bentonite composite super absorbent resin modified by PVA

      2018, 39(5):422-429. DOI: 10.7535/hbkd.2018yx05007

      Abstract (1421) HTML (0) PDF 2.26 M (1626) Comment (0) Favorites

      Abstract:In order to effectively use the alkali hemicellulose waste liquid produced by recycled fiber and paper industry in the production process, and solve the problems of high cost, poor salt resistance and low gel strength, etc., the hemicellulose-g-AA/bentonite SIPN composite super absorbent resin modified by PVA is prepared by introducing PVA under the condition of microwave radiation, using hemicellulose, partially neutralized acrylic acid, and bentonite as raw materials, ammonium persulfate-sodium bisulfite as initiator, N,N′-methylene-bis-acrylamide as crosslinking agent. The structure and performance of the products are characterized and tested by FTIR, TG and SEM. The effects of the introduction of PVA and its synergy with clay on the resin network structure, the solution adsorption performance and water retention properties are investigated. The results show that introducing an appropriate amount of PVA on the basis of hemicellulose-g-AA/bentonite can effectively improve the resin network structure. When the mass fraction of PVA is 3%, the water absorption rate and brine absorption rate of the resin increase by 40.6% and 34.7%, the three-demensional net structure of modified resin is effectively improved, and it shows good solution absorbency and water retention properties. In the comprehensive utilization of cellulose, the use of hemicellulose waste lye to prepare super absorbent resin can change waste into valuable, with obvious economic and social benefits.

    • >Mechanical, Electronics and Information Science
    • Adaptive sliding mode control for uncertain airplane control systems based on higher-order differential sliding mode surface

      2018, 39(5):430-437. DOI: 10.7535/hbkd.2018yx05008

      Abstract (1675) HTML (0) PDF 1.69 M (1459) Comment (0) Favorites

      Abstract:Airplane control system is a typical multitude input and multitude output (MIMO) nonlinear system with strong coupling and uncertainties, which would increase the controlling difficulty. The tracking control problem has been investigated for a class of airplane attitude control systems in this paper. Firstly, a new higher-order differential sliding mode surface is presented and its stability of the sliding mode surface is proved by coordinate transformation of airplane attitude control system and considering the existing of the input uncertainties. Then, a smooth adaptive sliding mode controller is design based on this higher-order differential sliding mode surface and the approximation ability of the neural network. Based on Lyapunov stability theory, it is proved that the designed controller not only ensures the airplane attitude control system with good tracking performance, but also avoids the appearance of the chattering phenomenon of traditional sliding mode controllers. Finally, the effectiveness of the proposed controller is verified by simulation results. The controller proposed in this paper has very fine application prospects in the field of airplane attitude control comparing the traditional one.

    • Development of 5 kW single-phase non-isolated inverter

      2018, 39(5):438-446. DOI: 10.7535/hbkd.2018yx05009

      Abstract (1383) HTML (0) PDF 5.31 M (1652) Comment (0) Favorites

      Abstract:Aiming at the weaker suppression ability of grid-connected inverters with traditional PI and proportional resonance PR control, a single-phase grid-connected inverter control scheme based on quasi-PR control strategy is proposed. A small-scale, low-cost single-phase non-isolated 5 kW inverter that can be used for large-scale power supply at home has been simulated and connected to the grid. The design principle of the inverter is expounded from two aspects of hardware and software. The simulation analysis is carried out by using the S-Function function in Matlab software. The control strategy is based on quasi-PR control and compared with the traditional PI and PR controllers. Based on the simulation, the experimental verification is carried out with an experimental prototype. The research results show that the proposed quasi-PR control strategy has great advantages compared with PI and PR control in eliminating steady-state error, improving grid-side current quality and resisting grid interference. Not only can it be better to achieve no static control, but also has scalability. With the static-free characteristics of the quasi-PR controller, the single-phase non-isolated 5 kW inverter will have broad application prospects in the home power supply system.

    • Attention-based BILSTM network with part-of-speech features for Chinese text classification

      2018, 39(5):447-454. DOI: 10.7535/hbkd.2018yx05010

      Abstract (3749) HTML (0) PDF 1.48 M (3270) Comment (0) Favorites

      Abstract:The Chinese classification methods based on LSTM can correctly identify the category oftext, but such classification methods mainly focus on learning the text fragments related to the theme without aiming at other aspects of the words in context, especially the implicit feature information contained in the part-of-speech. In order to use the part-of-speech information of words effectively to learn a lot of context-dependent feature information and then improve the performance of text classification, this paper proposes a Chinese classification method combining part-of-speech information, which can easily learn implicit features from words and their part-of-speech.To verify the effectiveness of the attention-based BILSTM model with part-of-speech for Chinese classification tasks, this paper designs a series of comparative experiments and conducts on source-open dataset. The experimental results show that the attention-based BILSTMmodel with part-of-speech has better performance on Chinese classification than some baselines, and it proves that the Chinese classification model proposed in this paper is effective.This indicates that identifying the category of text is not only highly correlated with the semantic information of the words, but also has a great relationship with the information of the words' part-of-speech.

    • Research on CCN cache algorithm under software definition

      2018, 39(5):455-461. DOI: 10.7535/hbkd.2018yx05011

      Abstract (1379) HTML (0) PDF 1.65 M (1355) Comment (0) Favorites

      Abstract:In order to solve the problems of caching in the content center network (CCN), based on the fusion architecture of content center network and software defined network (SDN), a method of CCN caching decision under the software definition is proposed, which makes full use of the advantages of global perception and centralized control in the control layer. The scheme considers betweenness centrality, content popularity, edge nodes and the limited storage of cache nodes at the same time, and it proposes the concepts of control node and communication node, so that the request contents can be cached reasonably at different nodes according to the controller's cache decision. Meanwhile, the shortest path to the user request is found based on the hops of the control node to the cache node and the server. Simulation experiments are carried out using ndnSIM, and the results show that this scheme can obviously improve the cache hit rate, reduce the path extension rate and cache replacement number compared with the traditional caching strategies of ALWAYS and LCD, and the scheme achieve the purpose of improving the efficiency of CCN caching, which is beneficial to the development of the content center network and the future network.

    • >Special Column: New Energy Resources, Energy Conservation and Environmental Protection
    • Study on heat transfer enhancing performance of spiral groove tube in phase change heat storage for solar energy

      2018, 39(5):462-469. DOI: 10.7535/hbkd.2018yx05012

      Abstract (1393) HTML (0) PDF 1.40 M (1539) Comment (0) Favorites

      Abstract:Based on the energy storage problems for solar energy utilization and the advantages of spiral groove tube heat exchanger, spiral groove tubes are used in the solar energy phase change heat storage, with numerical simulation of the thermal storage process of heat reservoir. Firstly, the simulation method and the reliability of the used model are verified experimentally with smooth tube. Using spiral groove tube as water flow pipe and phase change material as heat storage medium, building the three-dimensional model by Gambit software and meshing by ICEM, the heat storage process in the spiral groove tube and smooth tube heat storage are numerically simulated while the heat transfer enhancing effect is investigated. The influence of structural parameters such as groove pitch and groove depth on the heat storage process is simulated numerically and the influence rules are analyzed. The results show that the convective heat transfer intensity and heat transfer capability are enhanced when the smooth tubes are substituted by spiral groove tubes in the phase change heat storage and the heat storage time become shorter. In the range of simulation, the optimal structural parameters of spiral groove tube is that the groove pitch p=7 mm and groove depth e=0.4 mm. The further improved design of phase change thermal storage can be realized in later research in-depth.

    • Preparation of the composite film based on CdS-modified TiO2 nanorod array with low density and its photoelectrochemical properties

      2018, 39(5):470-476. DOI: 10.7535/hbkd.2018yx05013

      Abstract (1611) HTML (0) PDF 2.24 M (1697) Comment (0) Favorites

      Abstract:In order to increase the filling ratio of CdS photosensitized layer into the TiO2 array, a low-density TiO2 nanorod array with short-length rods and large rod-interval is prepared based on the TiO2 seed layer-coated FTO conductive glass through hydrothermal process. CdS seed layer is covered onto the TiO2 nanorod by chemical bath deposition. Then CdS photosensitized layer is grown in the TiO2 nanorod array via hydrothermal approach. SEM, XRD, UV-Vis absorption spectra are employed to characterize the TiO2/CdS composite films with different hydrothermal time of CdS. The photoelectrochemical properties of the TiO2/CdS composite film are also studied. The results indicate that the low-density of the TiO2 nanorod array could facilitate the infiltration of the CdS growth solution into the TiO2 array to form the perfect coverage with CdS seed layers. CdS photosensitized layers are homogeneously grown on the whole TiO2 nanorods and gradually filled in the TiO2 array through hydrothermal process. Meanwhile, flower-like CdS modified layers composed with short-length rods are formed at the top of composite film array. The light absorption of the TiO2 nanorod array is extended to the visible region with the CdS modification. The photocurrent of the TiO2/CdS composite film is obtained via 7 h hydrothermal growth of CdS layer. The excellent photoelctrochemical performance of the composite film of CdS modified TiO2 nanorod array with low density reveales its application prospect in solar cells.

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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