Volume 39,Issue 2,2016 Table of Contents

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  • 1  Bifurcation characteristics of a nonlinear planetary gear train changing with power
    LI Tongjie JIN Gunaghu BAO Heyun ZHU Rupeng
    2016, 39(2):1-9. DOI: 10.11835/j.issn.1000-582X.2016.02.001
    [Abstract](1385) [HTML](288) [PDF 2.84 M](949)
    Abstract:
    As the motion state of a planetary gear reducer is easy to bifurcate when the transmitted power changes, a study on the bifurcation characteristics of a planetary gear train changing with the transmitted power is explored in this paper. The local bifurcation characteristics were studied with CPNF(continuous Poincaré-Newton-Floquet) method on the basis of the nonlinear torsional vibration model of 2K-H planetary gear train. As a comparison, the global bifurcation diagram changing with power was calculated by using the method of numerical integration. The comparison results reveal that a nonlinear planetary gear train with certain parameters may have several coexisting periodic trajectories, some of them may be stable and some may be unstable. As the power gradually increases in the range of 196~220 kW, the stable asymptotic stable periodic trajectory may change into chaos in the way of inverse period doubling bifurcation. And chaos is easy to appear when the planetary gear train is under light load condition.
    2  Optimal design of vibration and noise reduction of the cutting plate
    LIN Lihong WANG Cheng WANG Kai WEN Qin
    2016, 39(2):10-16. DOI: 10.11835/j.issn.1000-582X.2016.02.002
    [Abstract](1087) [HTML](290) [PDF 2.70 M](815)
    Abstract:
    To reduce vibration and noise of the cutting blade in working process, a finite element model of the cutting blade was established by ANSYS APDL. Load was given by inversions to simplify the model and analysis the process, and the results show that the vibration amplitude of the cutting blade can be reduced by rectifying the parameters. Based on the square relationship between the vibration energy and the velocity, we designed an optimization program by taking the quadratic sum of the speed of the test point as the objective function to optimize the cutting blade model, and acquire a set of optimized data, which can provide basis for actual production.
    3  Reliability analysis on the shrink disc connection of a wind turbine gearbox based on ANSYS/PDS
    ZHANG Xun SUN Yizhong HE Aimin CHANG Tao WANG Hong
    2016, 39(2):17-24. DOI: 10.11835/j.issn.1000-582X.2016.02.003
    [Abstract](2031) [HTML](428) [PDF 4.09 M](1413)
    Abstract:
    An axisymmetric and parameterized finite element model for the shrink disc connection of a wind turbine gearbox was established. And the torque from the shaft was taken into consideration and the non-linear finite contact software ANSYS was used to analyze the model's strength. As material properties, processing tolerance, boundary conditions and loading, etc. affect the accuracy of analysis, we used PDS module in ANSYS and based on structure failure mode to determine the structure function, and then set up a structure limit state equation. The reliability of the shrink disc connection was calculated with Latin hypercube sampling of Monte Carlo method, and its reliability, failure probability and cumulative distribution were obtained. The results indicate that the transmission torque and the strength of components meet design requirements and the reliability of the connection reaches 94.8%. It's hoped to provide some references for the design of shrink discs in wind turbine gearboxes.
    4  A study on comprehensive evaluation of technological progress level of coal enterprises
    CAO Shugang WEI Yaxing
    2016, 39(2):25-33. DOI: 10.11835/j.issn.1000-582X.2016.02.004
    [Abstract](1262) [HTML](316) [PDF 1.26 M](1034)
    Abstract:
    According to the characters of coal enterprises, such as resource constraints, high-risk production and environmental destruction, etc., we established an evaluation index system of technical progress for coal enterprises, which consists of nine second indicators and 24 third indicators. By using 1-9 scale of AHP(analytic hierarchy process) method, 42 experts from different work units and professional fields were invited to obtain the index weight. According to the weight analysis, the optimal path to improve coal enterprises' technological level is to improve the quality of the whole staff,introduce high-level technical personnel and increase science and technology investment funds. Fuzzy comprehensive evaluation method was used to evaluate technology progress of coal enterprises. And a case study shows that this evaluation system can optimize coal industry development and management.
    5  Analysis on influencing factors of nitrogen removal via SND and optimization by RSM in SBBR
    CAI Jianminga CAO Jiashuna ZHOU Bibo
    2016, 39(2):34-43. DOI: 10.11835/j.issn.1000-582X.2016.02.005
    [Abstract](1156) [HTML](277) [PDF 5.19 M](925)
    Abstract:
    Nitrogen removal performance of SBBR reactor was investigated under the condition of continuous aeration with suspended packing by activated carbon coating modification. The results indicate that SBBR presents a good simultaneous nitrification and denitrification (SND) performance with the removal rates of NH3-N and TN at 80.7% and 63.1% respectively. During a typical cycle, SND rate can reach 72.8%. Single factor experiments show that nitrogen removal rate increases as the increase of aeration time and it increases first and then decreases as the increase of dissolved oxygen concentration and packing dosing quantity. Secondary multivariate regression model is established with using response surface methodology and taking dissolved oxygen concentration, packing dosing quantity and aeration time as inspective factors and nitrogen removal rate as evaluation index. 69.28% nitrogen removal rate as the maximum value is obtained under optimal working conditions according to the model calculation as follows:dissolved oxygen concentration of 2.37 mg/L, packing dosing quantity of 40.10%, aeration time of 5.17 h. Verification test show that the deviation rate between predicted values and measured values is 1.57%.
    6  Study on cooling effect of high density urban park and its simulations & predictions——Taking Tianjin center city as an example
    JIA Qi YUN Yingxia YIN Zekai
    2016, 39(2):44-50. DOI: 10.11835/j.issn.1000-582X.2016.02.006
    [Abstract](1266) [HTML](395) [PDF 2.81 M](1231)
    Abstract:
    Rapid urbanization results in the increase of population density of large cities. And urban heat island effect becomes severe. Park green spaces, as an important component of the city ecosystem, play a significant part in alleviating heat island. We choosed 8 large parks of Tianjin center city as empirical objects, used single window algorithm and analyzed their cooling effect based on Landsat8 ETM+image in 2013. The results show that the coverage areas of the parks and vegetation coverage ratio are the most important factors influencing the urban heat island effect, and also water ratio has a great influence on the surface temperature. The maximum cooling intensity and cooling distance of the 8 parks differ largely with each other. The cooling intensity temperature difference is about 2.72℃ and the cooling distance is 195 m. Parks with larger area has more obvious cooling effect, especially when the water ratio is higher than 30% or the vegetation coverage higher than level 10. A model of Parks' cooling effect is deducted based on the conclusion of the study. The results of the research provides effective technical support for the planning of park green space in Tianjin center city and similar high density urban areas.
    7  Research and analysis of an improved quadratic boost converter
    DONG Wenqi MA Buyun CAI Hongfei HOU Shiying CHEN Fu
    2016, 39(2):51-57. DOI: 10.11835/j.issn.1000-582X.2016.02.007
    [Abstract](1368) [HTML](348) [PDF 3.35 M](984)
    Abstract:
    The traditional quadratic boost converter has the high step-up ability, but it needs high voltage and large current stress, which increases the volume and the cost. Based on the traditional boost converter and a high step-up three-terminal network, an improved quadratic boost converter was presented. The converter's operation principle and its voltage and current stress of each switch were analyzed when it worked in continuous conduction mode(CCM). The result shows that the presented converter has not only higher step-up ability, but lower voltage and current stress in the case of same output voltage. At last, simulation proved the converter's correctness and feasibility.
    8  Power source of short circuit breaking and making test for mining high-voltage switch
    CHEN Zhao
    2016, 39(2):58-63,106. DOI: 10.11835/j.issn.1000-582X.2016.02.008
    [Abstract](1240) [HTML](411) [PDF 2.22 M](1144)
    Abstract:
    In order to improve the performance parameters of domestic short circuit generators, we took a foreign short circuit generator as test power source, established a short circuit breaking and making test system on the basis of direct test method, and put forward a new technical scheme. Simulation results show that the scheme can meet the technical need and the testing criteria of the comprehensive mine electrical laboratory. The scheme provides a solving idea of constructing system for large capacity breaking test.
    9  Effect of hydrothermal pretreatment on thermophilic anaerobic digestion of food waste
    WANG Pan GUO Xinyuan LU Qingyu REN Lianhai LI Bingxin CHONG Yuxuan HUANG Yanbing
    2016, 39(2):64-70. DOI: 10.11835/j.issn.1000-582X.2016.02.009
    [Abstract](1241) [HTML](306) [PDF 2.08 M](1073)
    Abstract:
    Anaerobic fermentation tests were carried out with 20% solid content at the temperature of 55℃ to investigate the effect of hydrothermal pretreatment on thermophilic anaerobic digestion of food waste. Orthogonal test L9 (33) was employed to determine the effects of water addition ratio, temperature and time. The results show that the physical and the chemical properties of food waste change significantly after hydrothermal treatment. The daily biogas production, the cumulative biogas production and the removal rates of TS and VS of food waste increase significantly after pretreatment. When the water addition ratio is 50%, temperature is 120℃ and pretreatment time is 80 min, we get 101 050 mg/L SCOD, which is 5.6 times of that of the untreated group. The peak values of daily and cumulative biogas production also reach the maximum under these pretreatment conditions. The maximum cumulative biogas production is 269.10 mL/g VS, which increases by 49.4% than that of the untreated group. The influences of the three factors on thermophilic anaerobic fermentation of food waste are temperature>time>water addition ratio. The effects of temperature and time of hydrothermal pretreatment on food waste fermentation are evident, while the effect of water addition ratio is less evident.
    10  Big data and security visualization
    XIANG Hong ZHANG Yu HU Haibo
    2016, 39(2):71-81. DOI: 10.11835/j.issn.1000-582X.2016.02.010
    [Abstract](1795) [HTML](431) [PDF 2.74 M](1629)
    Abstract:
    The rapid development of IT technology opens an unprecedented age of big data. The massive amounts of information gives us more data. Meanwhile, all kinds of security problems follow. Data visualization techniques can help us to identify the possible security threats in the system roundly and timely, evaluate system security and ensure the security of infrastructure. In this paper, we first classified security data according to the feature of big data from data perspective; then, summarized the existing visualization tools and technology based on all types of security data so that we can use mature data security visualization technology for the researches of big data security; at last we outlined guidelines and directions for future studies.
    11  A matching model algorithm of design requirements and design services for cloud manufacturing
    YANG Juan WU Kehong
    2016, 39(2):82-88. DOI: 10.11835/j.issn.1000-582X.2016.02.011
    [Abstract](1454) [HTML](310) [PDF 2.73 M](1441)
    Abstract:
    According to the diverse, dynamic, multi-restrictive and multi-level characteristics of design requirements and design services under the environment of cloud manufacturing, we proposed a new kind of data structure definition for design requirements and design services, which contains attribute sets, relationship sets and operation sets. Based on this, we established a design requirement and design service matching model with input, decomposition, combination and output. The model matching processes include atom matching, extension matching and product matching. To solve the quantitative problems of input, decomposition, combination and output in matching processes, we adopted semantic similarity and circulating recursive structure to design a matching algorithm to realize intelligent matching. We verified the effectiveness and feasibility of the proposed model and the key implementation technologies through experiments.
    12  A robust license plate location algorithm based on multi-scale feature fusion corner detection and visual color features
    CHEN Zhuang YANG Feng FENG Xin CUI Shaoguo LI Bo
    2016, 39(2):89-98. DOI: 10.11835/j.issn.1000-582X.2016.02.012
    [Abstract](1451) [HTML](303) [PDF 3.14 M](1151)
    Abstract:
    Scale, affine variance and complex background are important factors affecting the accuracy of license plate location. We presented a method of license plate location based on multi-scale product of corner detection and visual color features in difference of Gaussian (DOG) scale space. Based on the image edge information in DOG scale space, we first extracted scale-and-affine-invariant corner and color features through multi-scale multiplication, and then obtained the candidate license plate location by fusing the corner and the color features. Finally, we accurately located the license plate by using the distance between the feature points in the plate region and the intensive relationship of the points. Experiments on several real-world vehicle image data sets under complex conditions have verified the proposed method has high effectiveness and efficiency in locating license plates, and greater performance in robustness of noise and affine variance than other state-of-art license plate localization methods.
    13  Modeling analysis on the prediction of the cost of diseases
    ZHANG Jingfang LI Jiacheng REN Jiashun
    2016, 39(2):99-106. DOI: 10.11835/j.issn.1000-582X.2016.02.013
    [Abstract](1292) [HTML](326) [PDF 1.23 M](1439)
    Abstract:
    On the basis of the per capita treatment cost per month of five common diseases, i.e. diabetes, intestinal polyp, hyperthyroidism, eutocia and cerebral infarction, in a 3-A-grade hospital in Chongqing from January, 2012 to December, 2014, we used BP neural network, generalized regression neural network (GRNN), grey system GM (1, 1) and non-linear regression analysis to predict the change of per capita treatment costs per month of these five diseases from January 2015 to August 2015. And the accuracy of these four models was judged by comparing the prediction results with real data. The results show that the minimum coefficients of determination (R2) of the four models are 0.278, 0.565, 0.048 and 0.097, respectively, while their maximum coefficients of determination(R2) are 0.826, 0.901, 0.600 and 0.747, respectively. The minimum prediction errors of the four models are 9.845%, 3.507%, 5.897% and 3.642%, respectively, while their maximum prediction errors are 15.450%, 13.940%, 30.518% and 17.204%, respectively. Compared with the other three models, the GRNN model can predict the cost of diseases more accurately.
    14  Preparation of TiFe based alloys melted by BaZrO3 crucible and its hydrogen storage properties
    LI Chonghe ZHOU Han CHEN Guangyao HU Renmin WU Zhu LI Zhilin
    2016, 39(2):107-113. DOI: 10.11835/j.issn.1000-582X.2016.02.014
    [Abstract](1927) [HTML](449) [PDF 2.10 M](1673)
    Abstract:
    TiFe-based hydrogen storage alloy was prepared by using a self-made 25 kg BaZrO3 crucible with ZG-0.05 type vacuum induction melting system. The melting conditions are argon atmosphere of 0.6 MPa, refining time of 5~10 min and temperature of 1 450℃. The chemical composition of the as-cast sample was examined by means of inductive coupled plasma emission spectrometer (ICP) first, and then its microstructure, surface topography, element distribution in micro-domains and phase were examined by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS), and finally its PCT curves were measured by gas reaction controller. The results show that, the oxygen contents of alloys prepared by the BaZrO3 crucible and the graphite crucible are are less than 0.1%(ω), meanwhile the carbon content of alloys obtained by the electro graphite crucible is 0.417%(ω), which exceeds the tolerance of commercial alloys (1 000 ppm). The microstructure of the alloy melted by the BaZrO3 crucible is equiaxed crystal, but the alloy melted by the graphite crucible is composed of the equiaxed crystal and the spherical TiC particles distributed along grain boundaries or within the grain. The maximum amount of hydrogen absorption of the alloy melted by the BaZrO3 crucible is larger than that of the alloy melted by the graphite crucible, and the hydrogen desorption and absorption plateau pressure of the alloy meted by the BaZrO3 crucible is also lower.
    15  Synthesis and visible-light photocatalytic activity of WO3/g-C3N4 composite photocatalysts
    WANG Pengfei GUI Mingsheng
    2016, 39(2):114-122. DOI: 10.11835/j.issn.1000-582X.2016.02.015
    [Abstract](1914) [HTML](348) [PDF 4.07 M](1062)
    Abstract:
    The WO3/g-C3N4 composite visible photocatalysts were successfully synthesized by an ultrasound-microwave-protonation process using HCl solution as solvent. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) and Brunauer-Emmett-Teller (BET) specific surface area and photogradation of Rhodamine B (RhB) for visible-light properties. This results show that the composite catalysts are composed of WO3 nanosheets loading on g-C3N4 nanoplates. When the mass fraction of WO3 is 40%, the sample prepared by heating the precursor at 500℃ for 2 h has better photocatalytic activity than that prepared by pure WO3 and g-C3N4. The WO3/g-C3N4 can photodegradate 98% 100 mL RhB solution with concentration of 10-5 mol/L after 5 h visible-light (wavelength is larger than 420 nm) irradiation.
    16  Analysis of the failure modes for continuous buried pipeline crossing the normal fault region
    XUE Na LI Hongjing LI Xiuju JIN Liu ZHAI Juyun
    2016, 39(2):123-130. DOI: 10.11835/j.issn.1000-582X.2016.02.016
    [Abstract](1381) [HTML](303) [PDF 2.73 M](1440)
    Abstract:
    Tensile, shear strength and other forms of damages, even buckling failure in local compression zones will happen to buried pipelines under the action of ground permanent large deformation caused by normal fault movement. We used ABAQUS software to establish a three-dimensional pipe-soil interaction model under the ground permanent deformation, adopted nonlinear contact method to simulate the pipeline-soil interaction, and analyzed the influence of different pipe-diameters and crossing angles on the failure mode. By analyzing some examples, it is showed that tensile strength damage is prone to happen to small-diameter pipelines, while buckling failure to thin-wall large-diameter pipelines, and the critical value of pipe-diameter from intensity damage to buckling failure is 0.65 m. When crossing angle is bigger than 90°, the bigger the angle is, the easier buckling failure happens. And the critical value of crossing angle from intensity damage to buckling failure is 100°.
    17  Effect of the freeze-thaw damage on the durability of recycledconcrete and the bonding performance of steel
    WANG Chenxia QIAN Jianxun WANG Hao XU Kuo CAO Fubo
    2016, 39(2):131-139. DOI: 10.11835/j.issn.1000-582X.2016.02.017
    [Abstract](1302) [HTML](407) [PDF 3.48 M](1090)
    Abstract:
    Four groups of concrete test-pieces were made. The first two group test-pieces, RC1 and RC2, were made from recycled 100% coarse aggregate concrete with and without air-entraining agent respectively. The second two group test-pieces, NC1 and NC2, were made from common concrete with and without air-entraining agent respectively. Then, we studied the compressive strength, the mass loss rate and the dynamic elastic modulus loss rate of the test-pieces after different times of freeze-thaw cycles. It is shown that the compressive strength, the mass loss rate and the dynamic elastic modulus loss rate of all groups reduce after freeze-thaw. While these parameters of NC1 and RC1 which contain air-entraining agent decrease less. After 200 times of freeze-thaw cycles, the loss of the compressive strength of RC1 is close to 40%, the mass loss rate is 0.5%, and the loss rate of the dynamic elastic modulus is 38.5%. Another group of test-pieces, ZRC, which has the same components as RC1, were used for center drawing tests. And it's found that there are two forms of damage, splitting failure and steel pull-out damage, after freeze-thaw cycles. The ultimate bond stress between recycled coarse aggregate concrete and reinforcing bar reduces as the times of freeze-thaw cycles increase. After 200 times of freeze-thaw cycles, the ultimate bond stress reduced 33.5%. There is a rising section and a descending section in the load-slip curve.
    18  The effect of tunnel light source and tunnel light color todrivers’ visual performance
    DENG Min DAI Yanming
    2016, 39(2):140-145. DOI: 10.11835/j.issn.1000-582X.2016.02.018
    [Abstract](1338) [HTML](314) [PDF 2.68 M](1274)
    Abstract:
    Brightness and illuminance level are the only factors to be considered in the present tunnel lighting specifications and standards of CIE and countries all over the world, but color temperature, color rendering index and light spectrum distribution can also influence visual effect. We selected two tunnels to carry out a small target identification experiment and a color temperature reaction time test, and then analyzed the effect of tunnel lighting CRI (color rendering index) and CT (color temperature) on the driver's visual performance. The outcome shows that the bigger the CRI, the better the driver's visual performance is. For light sources with the similar spectral energy distribution, when the background brightness is the same, the more short waves in the light sources, the better the visual performance is.
    19  The design of a tubular photocatalytic reactor and itspurification effect analysis
    ZHENG Jie WU Siqi WANG Xiaoyan SONG Xuerui
    2016, 39(2):146-152. DOI: 10.11835/j.issn.1000-582X.2016.02.019
    [Abstract](1137) [HTML](320) [PDF 2.06 M](1065)
    Abstract:
    A tubular photocatalytic air purifier was designed on the basis of photocatalytic purification theory. With formaldehyde as experimental pollutant, its purification effect was compared with that of the traditional plate type reactor. The results show that the purification effect of the tubular reactor is better than that of the plate type reactor, and the degradation efficiency increases by 14%. Orthogonal tests show the significance level of the factors affecting purification efficiency is environmental temperature > initial concentration of formaldehyde >P25 TiO2 load. The best catalytic conditions of the tubular photocatalytic air purifier are environmental temperature 25℃, P25TiO2 capacity 1 mg/cm2 and initial concentration of formaldehyde 0.7 mg/m3. Under the best catalytic conditions, the degradation rate of formaldehyde can achieve 89% within 120 min.

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