Editor in chief：朱立光
International standard number：ISSN 1008-1542
Unified domestic issue：CN 13-1225/TS
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2015, 36(3):225-231. DOI: 10.7535/hbkd.2015yx03001
Abstract:As a new technology, helical milling has been widely used in hole-making of titanium alloy, and the surface roughness is an important indicator for evaluating the quality of titanium alloy hole. In this paper, the helical milling experiments are carried out to study the effect of machining parameters on the surface roughness with the model established in Matlab. It is proved that the model can well predict the influence of the helical milling parameters on surface roughness. With screw pitch increasing, the surface roughness of titanium hole firstly decreases and then increases in the range of 0.15~0.25 mm/rev. However, the surface roughness increases gradually at first and then decreases with the increasing of the feed per tooth in the range of 0.03~0.05 mm/tooth. Similarly, with the increasing of spindle speed, the surface roughness firstly increases, then decreases, and again gradually increases smoothly in the range of 2 500~3 500 r/min. The results in the work can provide experimental basis for optimizing cutting parameters and decreasing surface roughness in helical milling process.
2015, 36(3):232-239. DOI: 10.7535/hbkd.2015yx03002
Abstract:Currently, most Chinese CNC machine tools’ dynamic and static performances have large gap comparing with the similar foreign products, and the CNC machine tools users’ human-centered design demand are ignored, which results in that the domestic CNC machine tools’ overall competitiveness is relatively low. In order to solve the above problem, the ergonomics and coupling bionics are adopted to study collaborative optimization design method for CNC machine tools based on the domestic and foreign machine tool design method research achievement. The CNC machine tools’ “man-machine-environment” interaction mechanism can be built by combining with ergonomic, and then the CNC ergonomic design criteria is obtained. Taking the coupling bionics as theoretical basis, the biological structures “morphology-structure-function-adaptive growth” multiple coupling mechanism can be studied, and the mechanical performance benefits structure can be extracted, then the CNC machine tools’ structural coupling bionic design technology is obtained by combining with the similarity principle. Combination of CNC machine tools’ ergonomic design criteria and coupling bionic design technology, and considering the CNC machine tool performance’s interaction and coupling mechanisms, a new multi-objective optimization design method can be obtained, which is verified through CNC machine tools’ prototype experiments. The new optimization design method for CNC machine tools can not only help improve the whole machine’s dynamic and static performance, but also has a bright prospect because of the “man-oriented” design concept.
2015, 36(3):240-246. DOI: 10.7535/hbkd.2015yx03003
Abstract:Semiconductor refrigeration was used for heat dissipation of high power LEDs. A practical temperature-controlling system was designed and built with a microcontroller unit (STC89C52) and a thermoelectric cooling module (TEC1-12703) as the core components. Functions including temperature measurement, display, setup, and control were realized. PWM (pulse width modulation) was applied to regulate the driving current of the thermoelectric cooler. Effective refrigeration and temperature control were thus achieved. This system was used for the temperature control of a LED module with the power of 7×3 W. When the environment temperature was 22～25 ℃, the substrate temperature of the LED module could be stabilized in the range of 40～70 ℃. If the upper and lower temperature limits of the LED substrate were set to be 64 ℃and 65 ℃, respectively, the power consumed by thermoelectric cooling was only 27% of that consumed by the LEDs. The temperature-controlling system had a high cooling speed (up to 14 ℃/min) and small temperature fluctuation (only ±0.5 ℃). It fulfilled the requirements for LED temperature control and could be used for many other applications.
2015, 36(3):247-250. DOI: 10.7535/hbkd.2015yx03004
Abstract:The mass benchmark is the only real benchmark among all fundamental physical SI units, and the drawback is that it's easy to be affected by the environment, resulting in the change of the mass value. In this paper, recent research progresses at home and abroad on the surface status predication are summarized and the prediction research method on the surface status prediction of weights in institutes home and abroad is presented, including the influence analysis on the mass standards during transferring from vacuum to air and establishment the mass observation model and absorption correction model,etc. Through the research on the surface status of weights and absorption correction technology, the mass measurement accuracy can be ultimately enhanced, which lays a technical foundation for the upcoming redefinition of mass units' research.
2015, 36(3):251-254. DOI: 10.7535/hbkd.2015yx03005
Abstract:Dual-temperature tube furnace is generally used to produce single crystal by chemical vapor transport (CVT). The temperature gradient of single-temperature tube furnace is used to grow NbSe2 single crystal by CVT. The obtained single crystals are characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the magnetization and resistance of NbSe2 single crystal under low temperature are measured. The NbSe2 crystal has a metallic luster and typical dimension of about 2 mm×2 mm. The single crystal NbSe2 shows superconducting transition temperature of 7.1 K and transition width of 0.3 K. The estimated superconducting volume fraction is around 79%. The method employed in this study can be applied to grow other single crystals by CVT.
2015, 36(3):255-262. DOI: 10.7535/hbkd.2015yx03006
Abstract:Novel polymeric Ag3PO4/g-C3N4 photocatalysts modified by trace Ag3PO4 are prepared via a facile method. The obtained Ag3PO4/g-C3N4 composite products are characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflection spectroscopy (DRS), and photoluminescence spectroscopy (PL). The photocatalytic activities of Ag3PO4/g-C3N4 samples are investigated by evaluating the decomposition of methyl orange (MO) under visible light irradiation. The results reveal that the polymeric material is doped by Ag3PO4, and the Ag3PO4 doping can hardly affect the crystallinity of the as-prepared g-C3N4 materials, but it improves greatly their visible light absorption and separation efficiency of photogenerated electron/hole pairs. The Ag3PO4/g-C3N4 photocatalysts exhibits significantly enhanced photocatalytic performance.
2015, 36(3):263-268. DOI: 10.7535/hbkd.2015yx03007
Abstract:In order to improve the anti-static performance of polyacrylonitrile(PAN) fiber, with PAN fiber as raw material, N, N-dimethyl acetamide (DMAC) as solvent, prepared PAN spinning solution.Then added different ratios of nano-ZnO, with good conductivity, to the PAN spinning solution by the method of ultrasound and mechanical stirring,prepared PAN/ZnO composite spinning solution. After that, PAN/ZnO nano-fibers with anti-static property were prepared by electrostatic spinning technique. The spin-ability of PAN spinning solution and PAN/ZnO spinning solution as well as the influence of different ratios of nano-ZnO to the crystallinity and the volume resistivity of PAN/ZnO nano-fiber are studied. The results indicate that the spinning solution has good spin-ability; when the concentration was 12%, spinning voltage was 18 kV, receiving distance was 15 cm, advancing speed was 0.0005 mm/s, under the condition of electrostatic spinning, can get nanofibers with uniform fiber diameter, good parallel straight degree and smooth surface; with the increase of nano-ZnO content, the surface of PAN/ZnO nano-fibers become rough but no obvious change in crystallinity, and the volume resistivity decreases.
2015, 36(3):269-278. DOI: 10.7535/hbkd.2015yx03008
Abstract:A series of organic solutions with different cellulose concentrations are prepared by dissolving natural cotton fibers in lithium chloride/dimethyl acetamide (LiCl/DMAC) solvent system after the activation of cotton fibers. Under different coagulating bath, the regenerated cellulose membranes are formed in two kinds of coagulation baths, and two coating methods including high-speed spin technique (KW-4A spin coating machine) and low-speed scraping (AFA-Ⅱ Film Applicator) are selected in this paper. The macromolecular structure, mechanical properties, crystallinity, thermal stability and wetting property of the regenerated cellulose membrane are characterized by Scanning Electron Microscope(SEM), Fourier Transform Infrared Spectroscopy (FT-IR)，X-ray diffraction (XRD), Thermogravimetric analysis (TG) and contacting angle tester. The effects of mass fraction, coagulation bath type, membrane forming process on the regenerated membrane properties are investigated. Experimental results show that the performance of regenerated cellulose membrane is relatively excellent under the condition of using the KW-4A high-speed spin method, water coagulation bath, and when mass fraction of cellulose is 3.5%. The crystallinity of the regenerated cellulose membrane changes a lot compared with natural cotton fibers. The variation trend of thermal stability is similar with that of cotton fiber. But thermal stability is reduced to some degree, while the wetting ability is improved obviously.
2015, 36(3):279-285. DOI: 10.7535/hbkd.2015yx03009
Abstract:Concerning the problem of the thermal safety and thermal stability of a novel 3-DOF deflection type PM motor, the thermal characteristics of this motor are analyzed. The heat production of this novel motor working in the rated and overload conditions is simulated for temperature field using finite element analysis software, and the motor's temperature contours under different operating conditions are derived. The research results validate the rationality of the structure design of this proposed novel motor, which provides a reference for the structure optimization and performance indicator improvement of this kind of motor.
2015, 36(3):286-292. DOI: 10.7535/hbkd.2015yx03010
Abstract:An online video edge detection device for bottle caps is designed and implemented using OV7670 video module and FPGA based control unit. By Verilog language programming, the device realizes the menu type parametric setting of the external VGA display, and completes the Roberts edge detection of real-time video image, which improves the speed of image processing. By improving the detection algorithm, the noise is effectively suppressed, and clear and coherent edge images are derived. The design improves the working environment, and avoids the harm to human body.
2015, 36(3):293-299. DOI: 10.7535/hbkd.2015yx03011
Abstract:Aiming at solving the convergence rate problem in the latter stage of circuit evolution design, adaptive HereBoy algorithm together with the population evolution idea of GA is adapted to study the impact of adaptive-adjust factor on the evolution of convergence rate. One circuit model which is based on the similarities between combinatorial circuit and neural network is proposed, on which the matrix encoding scheme of combinatorial circuit is discussed. Besides of this, extrint evolution is adapted to evaluate the circuits fitness value, and adaptive-adjust factor in GA is introduced to improve the population diversity and convergence rate. The implementation of 2-bit binary multiplier circuits evolution shows that the average evolution generations and the evolution time all reduce obviously than conventional HereBoy algorithm, and that the average increase rate raises with the increase of evolution generation in the latter stage of circuit evolution.
2015, 36(3):300-305. DOI: 10.7535/hbkd.2015yx03012
Abstract:The current sheet components locating scheme optimization needs a great deal of finite element analysis, which limits the fixture design efficiency. To reduce finite element analysis times, this paper proposes a modified particle swarm optimization algorithm based on the inertia weight, and through the secondary development of finite element software, the improved particle swarm optimization is applied to fixture locating scheme design. Taking the front fender of some vehicle as the living example, the fixture locating scheme is optimally designed, which proves the method effective.
2015, 36(3):306-312. DOI: 10.7535/hbkd.2015yx03013
Abstract:The effects of temperature, slippage effect and effective stress of coal on the coupled mechanism of deformation and gas glow are key issues to control coal and gas outburst and design the methane recovery engineering. Firstly, intact coal from Huaxing mine in Jilin Province is crushed and coal briquette specimen are made. Then the tri-axial coupled test setup of the deformation, gas flow and temperature developed by ourselves is adopted to investigate the effects of pore pressure, effective stress and temperature on the permeability of coal briquette specimen. The results show that: 1) Under the condition of low pore pressure, the permeability first reduces with pore pressure increasing, then at a threshold of pore pressure it rises with pore pressure increasing, which is called “slippage effect”. 2) The effective confining stress significantly influences the permeability. With increasing effective confining stress, the space of pores and cracks are compressed and the permeability reduces. 3) The temperature significantly influences the permeability and the permeability decreases with temperature increasing. The main reason is that the space of pores and cracks is compressed due to the temperature stress. Because of the constraint around, temperature compressive stress appears in internal coal samples. Coal pore and fracture space is compressed, and the sample permeability decreases. Besides, the viscosity of gas increases with temperature increasing. It decreases the trend of coal permeability . The temperature influence on coal permeability approximates to linear relationship. 4) The empirical permeability evolution equation with varying temperature, effective stress and slippage effects is presented. The coal is viewed as elastic medium, combined with effective stress principle and the empirical permeability equation, the coupled model of deformation and gas flow with varying temperature and slippage effects is built. Furthermore, the code based on the finite element method in MATLAB is developed. The effects of varying temperature and slippage effects on the deformation and gas flow are studied through a numerical case, and the results show that: 1) without the temperature and slippage effects the gas flow may be underestimated, and the temperature and slippage effects should be taken into account in the coupled analysis of the deformation and gas flow; 2) the effects of varying temperature, slippage effect and effective stress on gas flow can be reflected by the model in this paper, which provides a new method to predict gas flow.
2015, 36(3):313-318. DOI: 10.7535/hbkd.2015yx03014
Abstract:The filling mold process of semi-solid alloy blank influences severely the forming and properties of finished piece. In this paper, DEFORM is applied to simulate the process of cup-type 6061 alloy die forging casting. The influences of the temperature of semi-solid alloy blank, preheating temperature, and downward press speed of pressure head on process of mold filling and velocity field are investigated. The results show that the mold filling of semi-solid alloy paste smoothly fills along the whole of mould cavity in “total wall thickness” form when the temperature of semi-solid alloy blank is 620 ℃, preheating temperature of pressure head is 200 ℃ and speed of pressure head is 40 mm/s. Along with the increase of the preheating temperature of pressure head, the filling process of the semi-solid alloy paste trends toward stable when the temperature of semi-solid alloy blank is 620 ℃ and the speed of pressure head is 20 mm/s. Along with the increasing of the temperature of semi-solid alloy, the process of mould filling becomes off balance and the liquid becomes turbulent flow. The velocity field in the process of mould filling affects severely the structure uniformity of the finished product.
2015, 36(3):319-323. DOI: 10.7535/hbkd.2015yx03015
Abstract:The chromium content of millet is measured by HNO3-H2O2 digestion and electrochemical method. In the DTPA-HAc-NaAc system, the oxidation peak current of amalgam formed by hexavalent chrome ion is obtained in the plating mercury electrode, and the pre-treatment technology of wet digestion can meet the electrochemical determination. The optimized detection condition of electrochemical method for hexavalent chrome ion is 130 ℃ of digestion solution, 10 mL hydrogen peroxide, 38 mL nitric acid, and neutral of pH. The linear correlation coefficient of electrochemical method is 0.99, and the recovery of standard addition is 90%~110%. This method can be used to trace chromium (Ⅵ) determination in millet.
2015, 36(3):324-329. DOI: 10.7535/hbkd.2015yx03016
Abstract:The second tertiary combined model is applied to develop the second and third type reservoirs which have more oil layer quantity and strong anisotropism, compared to the regular main reservoir with polymer injection, whose seepage characteristics of polymer-injection-after-water-drive shows a remarkable difference, in addition. This development appears to have a larger effect on the remaining oil development and production. Simulating the second tertiary combined model by reservoir numerical simulation under different polymer molecular weight, polymer concentration, polymer injection rate on the polymer injection period, conclusions of the influenced seepage characteristics of original and added perforated interval pressure and water saturation are drawn. The conclusion shows that the polymer molecular weight could influence water saturation of added perforated interval; polymer concentration makes a significant impact on reservoir pressure; polymer injection rate has a great influence on the separate rate of original and added perforated interval. This research provides firm science evidence to the theory of the second tertiary combined model to develop and enhance oil injection-production rate.
2015, 36(3):330-336. DOI: 10.7535/hbkd.2015yx03017
Abstract:In order to further explore the pollution characteristics of volatile organic compounds in ambient air in winter and spring in Shijiazhuang City, the pollution characteristics of 62 volatile organic compounds (VOCs), monthly and quarterly variation, the correlation between VOCs and PM2.5, and the main sources of VOCs are investigated by using EPA TO-15 method. It shows that 40 organic compounds of the 64 VOCs have been quantitatively determined in winter and spring in the city, which are mainly acetone, benzene, carbon tetrachloride, dichloromethane, toluene, ethyl acetate, etc.. In the no-quantitatively determined components, higher ethanol, butyl acetate, butane etc. are detected. The VOCs concentration has positive correlation with the PM2.5 concentration during haze days.