Volume 43,Issue 3,2020 Table of Contents

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  • 1  Multi-task scheduling game with limited resources for cloud manufacturing
    SHU Xiao WANG Shilong KANG Ling YANG Bo YANG Xingxing ZOU Haixu
    2020, 43(3):1-11. DOI: 10.11835/j.issn.1000-582X.2019.004
    [Abstract](910) [HTML](498) [PDF 1.02 M](1179)
    Abstract:
    To solve the cloud service composition optimal-selection (CSCOS) problem in cloud manufacturing (CMfg), based on the deep analysis of the difficulties and shortcomings in current researches, an optimization model for multi-task scheduling with limited resources problem (MLSR) is proposed. Considering the interest conflicts of service demanders and important quality of service (QoS) indicators, the multi-task scheduling problem with limited resources is converted into multiple static non-cooperative game, and the service demander (SD), different execution manufacturing path of each task and comprehensive service level (CSL) are considered as game player, game strategy and game payoff of a game, respectively. On this basis, the process to seek the pure strategy Nash Equilibrium (PSNE) solution is compiled into an algorithm, whose solutions are the final manufacturing execution paths for each task. Finally, simulation results show the feasibility, effectiveness of both the model and algorithm.
    2  Optimization of pneumatic drag reduction of van type truck based on orthogonal test method
    XU Jianmin FAN Jianming
    2020, 43(3):12-26. DOI: 10.11835/j.issn.1000-582X.2020.302
    [Abstract](864) [HTML](601) [PDF 8.50 M](1071)
    Abstract:
    In order to optimize the aerodynamic drag coefficient of a van type truck, three kinds of pneumatic drag reducing devices such as the bionic drag reduction structure of the front part of the cab, the top and side vortex generators, and the bottom vortex generator are designed. The effects of main parameters of three kinds of single pneumatic drag reducing devices on aerodynamic drag are studied. The drag reduction effect of each pneumatic drag reducing device is analyzed in detail from three aspects:speed trajectory, pressure distribution and turbulent kinetic energy distribution,on the basis of which, the main parameters of the three kinds of pneumatic drag reducing devices are optimized by orthogonal test method, and the truck model with optimal drag reduction is obtained. The research shows that the influence of the length of the front part of the cab on the aerodynamic drag coefficient of the truck is greater than that of the tilt angle. The inclination angle and length of the optimal truck head shape are 135ånd 300 mm, respectively. The aerodynamic drag coefficient of the model is 0.721 4, and the drag reduction rate is 8.93% compared with the original model of the truck. The height and position of the vortex generator have a great influence on the drag reduction effect of the truck. The vortex generator can increase the energy of the flow field in the separation area of the tail of the truck, and reduce the tail vortex area and the pneumatic differential pressure. The order of influence of the three kinds of pneumatic drag reducing devices on the aerodynamic drag coefficient of the truck is as follows:bottom vortex generator, the bionic drag reduction structure of the front part of the cab, and top and side vortex generators. The air drag coefficient of the optimal van type truck model is 0.683 3, and the optimal drag reduction rate of the composite drag reducing device is 13.8%.
    3  The influence of staggered distance on flow-induced motion of two circular cylinders with passive turbulence control
    YANG Zuomei DING Lin YE Qianyun ZHANG Li
    2020, 43(3):27-35. DOI: 10.11835/j.issn.1000-582X.2020.03.003
    [Abstract](462) [HTML](504) [PDF 9.19 M](757)
    Abstract:
    Aiming at two cylinders which is a very typical multi-cylinder structure, the influence of staggered distances on the flow-induced vibration response characteristics of two circular cylinders is studied using numerical simulation method. and the interaction relation between the gap flow and the vibration response of cylinders is obtained. The results illustrate that FIM mode of two cylinders include periodic vibration, double-cycle vibration, multiple-periodic vibration, and quasi-periodic vibration. With the change of staggered spacing, the amplitude of upstream cylinder is almost unaffected, and maximizes at U*=6. For the downstream cylinder, the change of staggered distance will significantly affect the trend of amplitude curve, especially when T=0.6D (D is the diameter of the cylinder). With the change of inflow velocity, the amplitude curves of upstream and downstream cylinders intersect, and there is a critical reduced-velocity Uc*=7. When U* > Uc*, the amplitude of upstream cylinder is lower than that of downstream cylinder. It is the dominant region of gap flow for T>0.6D and U* <8. In this region, vortices shed from the upstream cylinder form a gap flow, which attaches to the surface of the downstream cylinder, leading to the advance of boundary layer separation of the downstream cylinder, and enhancing the vibration of the cylinder.
    4  Research on quality evaluation index of underground garage lighting based on identification
    CHEN Keji WENG Ji ZHANG Qingwen ZENG Jing
    2020, 43(3):36-46. DOI: 10.11835/j.issn.1000-582X.2020.03.004
    [Abstract](563) [HTML](480) [PDF 2.73 M](950)
    Abstract:
    In order to ensure the rapid recognition of other people's behaviors in underground garage and to improve user's sense of security and comfort, the experimental methods combining actual measurement and subjective evaluation are adopted for the inadequacies of the evaluation indicators in the current garage lighting standards and to investigate the light environment of the underground garage in Area B of Chongqing University. By analyzing measured data and evaluation results, Facereader software is used for verification. With referring to the standard values of outdoor lighting, from the perspective of identifying other people actions, it's presented semi-cylindrical illumination is a main indicator for evaluating garage lighting, and the scope of application of stereoscopic indicators is summarized. It is suggested that the semi-cylindrical illumination and stereoscopic indicators should be considered in the design of underground garage. The scope of application of the index suggests that the underground garage semi-cylindrical illumination should be no less than 6.5 lx, and the stereoscopic indicator should be no less 0.75 to achieve safe anti-infringement lighting. The research also haves important reference significance for the evaluation of lighting quality in similar dark indoor public spaces.
    5  Modeling and simulation of electromagnetic radiation of DC link in direct-drive elevator
    SHI Kaining WANG Xudong XU Xiaozhuo JI Shengyang
    2020, 43(3):47-54. DOI: 10.11835/j.issn.1000-582X.2019.008
    [Abstract](675) [HTML](645) [PDF 2.23 M](921)
    Abstract:
    Electromagnetic interference produced by direct-drive elevator drive system is one of the main interference sources affecting the normal operation of system. It has great power, wide frequency band and is hard to predict. For direct drive elevator system electromagnetic interference problem, the article adopts multiple software joint simulation method to predict the electromagnetic radiation interference of elevator drive system power cables. Through constructing the elevator vector drive control system, we extract the current of DC power supply as the interference sources, establish the power cable model of direct driving elevator in the electromagnetic simulation software FEKO and conduct simulation analysis of the electric field distribution under the effect of interference sources inside and outside the elevator. The simulation results show that the method of multi-software joint simulation has engineering reference value for electromagnetic compatibility simulation modeling of drive elevator.
    6  A generative adversarial network based on self-attention mechanism for text-to-image generation
    HUANG Honggu GU Zifeng
    2020, 43(3):55-61. DOI: 10.11835/j.issn.1000-582X.2020.03.006
    [Abstract](887) [HTML](928) [PDF 7.47 M](1294)
    Abstract:
    Automatic image generation is a challenging problem in computer vision for a long time. As a branch of this area, there are also challenges in text-to-image generation. With the fast development of deep learning, generative adversarial networks (GANs) give a new inspiration to the image generation because it can generate highly compelling images of various categories. In this paper, we introduce the self-attention mechanism to GAN and propose GAN-SelfAtt to improve the quality of images. Meanwhile, we implement GAN-SelfAtt using two different GAN frameworks, i.e., WGAN and WGAN-GP. The experimental results show that self-attention mechanism improves the resolution of generated images. The reason of this improvement is that the self-attention mechanism fixes the defect of convolution computation which only calculates the correlation in the local pixel region. In addition, our results show that the stability of GAN-SelfAtt during the training process is improved. This fixes the problem of mode collapse which appears in the original GANs.
    7  Tests of tensile properties of composite insulators at high and low temperatures
    MA Wenjun YAN Zhitao ZHANG Pu QIU Zhe YOU Yi
    2020, 43(3):62-69. DOI: 10.11835/j.issn.1000-582X.2020.03.007
    [Abstract](608) [HTML](752) [PDF 5.61 M](1037)
    Abstract:
    Composite insulators are composed of a core and a coat with metal attachments. The core is made of glass fiber reinforced plastics impregnated with an epoxy resin. This material is a kind of high strength and non-brittle composite. But the interface in an adhesive layer between a mandrel and an umbrella is the weak link, which is susceptible to mechanical damage in the areas with significant changing temperatures. The Instron1186 electronic universal testing machine is adopted to carry out the material mechanical property tests through controlling displacements, and the tensile properties of composite insulators under high and low temperatures are studied. The test shows that the mechanical failure load of composite insulators depends on the connection strength of the metal tool and the mandrel, and the main features of the failure are the slip of the end of the metal tool. Because the thermal expansion coefficient of the end fittings is significantly different from that of glass fiber reinforced epoxy mandrel, the mechanical properties of composite insulators are lower than normal temperature at high temperatures or low temperatures. Especially at a high temperature, the bonding-slip property of the metal tool and the core rod is greatly reduced.
    8  Randomized pushover analysis and parameter sensitivity of reinforced concrete frame structure based on Sobol’ method
    ZHANG Wangxi YANG Xuefeng ZHANG Jinyi XIONG Hao
    2020, 43(3):70-78. DOI: 10.11835/j.issn.1000-582X.2020.03.008
    [Abstract](637) [HTML](642) [PDF 1.33 M](914)
    Abstract:
    To investigate the random parameter sensitivity of reinforced concrete frame structure, Matlab and SAP2000 were used to program Sobol' method and randomized Pushover method. One plane frame structure was established to analyze the sensitivity of parameters to roof displacement. The parameters contained maximum value of horizontal earthquake influence coefficient, concrete compressive strength, elastic modulus of concrete, yield strength and tensile strength of steel bar and elastic modulus of steel bar. The results showed that the most sensitive and important parameter to roof displacement in randomized Pushover method was maximum value of horizontal earthquake influence coefficient and the randomness of remaining five parameters could be ignored in the analysis. In addition, two examples were used to verify the applicability of the findings in the multi-layer and high-rise frame structures.
    9  The semantic segmentation of driving regions on unstructured road based on segnet architecture
    ZHANG Kaihang JI Jie JIANG Luo ZHOU Xianlin
    2020, 43(3):79-87. DOI: 10.11835/j.issn.1000-582X.2020.03.009
    [Abstract](950) [HTML](970) [PDF 7.21 M](1307)
    Abstract:
    To improve the autonomous vehicle's ability to understand the scene of unstructured road driving regions, a semantic segmentation method of unstructured road for autonomous vehicle based on SegNet architecture is proposed. Deep convolutional encoder-decoder architecture is formed by traditional convolutional neural networks, and it can learn the feature map of unstructured roads automatically. By learning and training in the datasets, image semantic segmentation model can be acquired and used to predict the feasible driving area of unstructured roads directly, which is important for autonomous vehicle's scene understanding. The proposed approach outperforms in precision and segmentation consequent, while Dice coefficient reaches more than 80%.
    10  Pattern discovery of liquid level time series data in oil tank
    WEN Bilong MA Qiang LI Fei
    2020, 43(3):88-99. DOI: 10.11835/j.issn.1000-582X.2020.03.010
    [Abstract](649) [HTML](670) [PDF 7.91 M](1039)
    Abstract:
    The liquid level of oil tank time series data model is of great significance for oilfield production, management and disaster warning. Due to the miscellaneous data system in the field of oil and gas fields, these data are not classified and marked. There are some methods for manual screening and checking with graphical tools, which are not suitable for long time uninterrupted production of petroleum industry. In the face of the above problems and the shortcomings of the existing methods, a processing method which based on cascade piecewise linear representation and hierarchical clustering for the characteristics of reservoir tank level data is proposed. The observation sequence is transformed into discrete linear piecewise sequence, and each linear segment is clustered by unsupervised hierarchical clustering based on DTW distance, which can automatically discover the temporal pattern and assign identifiers to annotate the sequence. Based on the data of oil tank level sequence data, and the implied models and the changing rules were found. The method has a good ability to recognize and classify the time series change patterns of liquid level, without manual screening and inspection, and can view the changing patterns of different granularity according to the need, which can provide a reference and avenues for time series data pattern recognition and abnormality detection.
    11  Theoretical derivation of shear lag warping displacement function of box girder
    SHI Yuanxu WU Xiaoguang HUANG Cheng LI Yuanjun
    2020, 43(3):100-110. DOI: 10.11835/j.issn.1000-582X.2020.201
    [Abstract](564) [HTML](1797) [PDF 2.26 M](1153)
    Abstract:
    In order to study the reasonable warping displacement function of shear lag of box girder, plate flange is regarded in this paper as an elastic body connected by a spring with certain stiffness in longitudinal parallel and a flange plate spring model is established according to the longitudinal force and deformation characteristics of flange plate of box girder. And based on energy variational principle, flange plate equilibrium differential equation is established, deducing that the longitudinal displacement function is a linear combination of hyperbolic function and triangular function. The warping displacement function is determined as three single forms:hyperbolic sinusoidal function, hyperbolic cosine function and sinusoidal function. By substituting three function forms into the shear lag variational equation, the bending normal stress equations of the three longitudinal displacement functions are obtained. In order to verify the rationality of the three functions derived from the theory, the normal stress of flange plate calculated by the three functions is compared with the measured value, the calculated value in the form of cubic parabola, and the calculated value of solid finite element. The effect of different function forms on the stress distribution of flange plate is analyzed from the perspective of the function property. The results show that the calculated value of sinusoidal function is in good agreement with the measured value and the calculated value of solid finite element method. In addition, the second derivative of the function is positively correlated with the stress distribution of the flange plate.
    12  Review on the influence paths of unsafe behavior of construction workers
    YE Gui YANG Lijuan WANG Yuhe WEI Yao FU Yuan
    2020, 43(3):111-120. DOI: 10.11835/j.issn.1000-582X.2020.03.012
    [Abstract](824) [HTML](496) [PDF 1.61 M](1729)
    Abstract:
    Unsafe behavior of construction workers is the main cause of construction safety accidents. Research on the influencing factors and influence paths of unsafe behavior of construction workers is one of the key scientific issues to reduce unsafe behavior of construction workers. To reduce construction worker's unsafe behaviors, this paper reviewed the research results of the influencing factors of unsafe behavior of construction workers from three aspects:individual, organization and society, and combed the influence path of influencing factors. Based on the induction and summarization of literature reading, it was concluded that in the future, we should further study the influence path of unsafe behavior of construction workers from the perspective of cognitive psychology, and pay attention to the study of the influence process of environmental factors and individual interactions on unsafe behaviors. Moreover, attention should be paid to the impact of informal groups in the construction industry on unsafe behavior. The research results will help to improve the theoretical study of safety management and improve the level of safe production.

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