Volume 41,Issue 11,2018 Table of Contents

1 Analysis of cable force simulation for single cable glass curtain wall based on frequency method

HUANG Yin , SUN Yuli , CHENG Wenxing , XU Shitong

2018, 41(11):1-7. DOI: 10.11835/j.issn.1000-582X.2018.11.001

[Abstract](1340) [HTML](352) [PDF 1.22 M](1420)

Abstract:
In order to study the accuracy of frequency method applied to monitoring the cable force of single cable glass curtain wall, based on the cable force monitoring project of some single cable glass curtain wall, finite element software ANSYS was used to establish the vibration model of the single cable glass curtain wall under different boundary conditions, and the simulated frequencies were compared with the measured frequencies. The results showed that the boundary condition of the curtain wall cable is closer to the fixed ends, and the shorter cable is more obvious;the higher order frequencies (n=3~6) are more stable than the lower order frequencies (n=1~2). The frequency correction coefficient was obtained by comparision of the measured frequency with the simulated frequency(n=3~6), and the number was 0.968 calculated by string theory formula. A modifier formula was proposed, which was suitable for the cable of single cable glass curtain wall whose ratio of length to diameter was between 270~340. The modifier formula was verified by the bow type dynamometer method, and the relative error of the cable force was -5.4%, which showed that the calculation accuracy of the curtain wall cable force could be effectively improved by the modifier formula.

2 Study on force correction method of reinforced concrete brace shaft in foundation ditch based on strain monitoring

XIAO Zhenye , LI Suzhen , CUI Xiaoqiang

2018, 41(11):8-18. DOI: 10.11835/j.issn.1000-582X.2018.11.002

[Abstract](675) [HTML](569) [PDF 3.71 M](1218)

Abstract:
The axial force of braces is an important index to verify the safety of foundation ditch supporting system, and it is of great significance to the safety judgment of foundation ditch during construction. But the monitoring data of the braces axical force in the field is obviously divorced from reality, and the axial force data monitored often exceeds the actual safety design value several times, so it is difficult to be an effective indicator of safety monitoring. Considering the influence of non-load factors on the strain data of reinforced concrete support, the CEB90 model is chosen as an example to correct the strain, and the corresponding calculation theory and method are put forward. The axial force of the actual support monitoring data is corrected, and the axial force changes before and after the correction are compared. The results show that the non-load factors have a great influence on the axial force monitoring, which indicates that the non-load factors should be considered in the monitoring of the axial force of the reinforced concrete braces.

3 Study of nonlinear dynamic constitutive model of coarse grained soils based on Hardin-Drnevich skeleton curve

LI Yangbo , ZHANG Jiasheng , ZHU Zhihui , WANG Xuan , CHEN Wensheng

2018, 41(11):19-30. DOI: 10.11835/j.issn.1000-582X.2018.11.003

[Abstract](879) [HTML](746) [PDF 4.32 M](1650)

Abstract:
In order to study the dynamic deformation characteristics of subgrade filler of coarse grained soils for high speed railway, the consolidated undrained triaxial tests were carried out by large-scale triaxial test system. Firstly, based on Hardin-Drnevich skeleton curve, the dynamic shear stress-strain curves for loading and unloading were constituted by Masing rules, and the equations of incremental tangent shear modulus of the skeleton curve and hysteresis curves were derived. Using the secondary development platform of ABAQUS, the nonlinear dynamic model subprogram based on Hardin-Drnevich skeleton curve and Masing rules of coarse grained soil was compiled. Study results show the nonlinear dynamic model fit triaxial test results well as the program code was applied to dynamic response analysis of high speed railway. Compared to Mohr-Coulumb constitutive model, the nonlinear dynamic constitutive model can reflect dynamic response characteristics of railway subgrades better.

4 Design parameters and reliability analysis of Q345 steel axial loading member under high temperature

WANG WeiYong , XIA Yue

2018, 41(11):31-41. DOI: 10.11835/j.issn.1000-582X.2018.11.004

[Abstract](870) [HTML](642) [PDF 1.10 M](795)

Abstract:
In current Chinese code for design of steel structures, the design values of all kinds of steel at mbient temperature have been listed, but there is no design value for steel at high temperature. In order to analyze the design values of steel under high temperature, 152 groups of mechanical properties of Q345 steel at high temperature were collected and the statistical parameters of material property uncertainties of Q345 steel under high temperature were obtained. The finite element model was established in the general finite element software ABAQUS to calculate the ultimate loading capacity of 360 groups of Q345 steel axial loading member under high temperature and the statistical parameters of model uncertainties of Q345 steel axial loading member under high temperature were generated. The partial factors for resistance of Q345 steel under high temperature were proposed by using the first-order second-moment reliability method which was programmed through Matlab and the reliability of the proposed resistance partial factors were checked. The result meets the reliability requirement of building in fire and have sufficient reliability.

5 Thermal performance and energy saving potential study on a thermo-activated PCM building system

ZHU Li , YANG Yang , CHEN Sarula , SUN Yong

2018, 41(11):42-52. DOI: 10.11835/j.issn.1000-582X.2018.11.005

[Abstract](625) [HTML](434) [PDF 7.09 M](950)

Abstract:
Based on the clean energy heating context in China, a novel thermo-activated PCM composite building envelope system was proposed to further reduce building energy consumption and improve indoor comfort by utilizing low-grade hot water produced by valley current. A comprehensive heat transfer model was built and validated by comparing with reference test results. Under the condition of heating season in cold area like Tianjin, the effects of pipe spacing, PCM thickness and orientation on thermal behavior and energy saving potential were numerically investigated. The results show that the thermal performance of the composite wall has been changed, and the primary energy as well as the operation cost, taking south wall for example, are reduced by 14.07% and 56.03%, respectively. The pipe spacing shows a more obvious influence than PCM thickness, thereby 100 mm for pipe spacing and 30 mm for PCM thickness seem to be the satisfactory values when taking the thermal resistance and heat charge/discharge into account simultaneously. Orientation has big influence on the performance and the improvement in north orientation is most obvious among the four orientations. The primary energy and operation cost saving ratio in north orientation show a reduction by 20.3 and 9.0 percent respectively compared with that in south. This study can provide reference for pipe-embedded PCM envelope design and its application to buildings of clean heating and low energy consumption.

6 An algorithm for calculating transient-state signal parameter of distribution network

ZHANG Changchun , WANG Yifu , LIU Gang , LI Dawei

2018, 41(11):53-58. DOI: 10.11835/j.issn.1000-582X.2018.11.006

[Abstract](592) [HTML](371) [PDF 807.54 K](857)

Abstract:
For some applications such as variable branch protection and user-side protection in distribution network that need to calculate the steady-state current and voltage values as soon as possible, how to deal with current and voltage transient fault signal in a short period of time has become a problem that we face. The existing power grid fault signal processing methods are usually limited in the length of sampling data and the quantity of parameters with the result that the count of current and voltage fault transient signal is hard and takes a long time. This article was based on the characteristics of fault transient voltage and current in distribution network, and established a model including stable-state power frequency component and decaying DC component to approximately characterize distribution network fault transient voltage and current. The particle swarm-Gauss Newton hybrid algorithm was used to identify the parameters of this model and the transient parameters were obtained. The simulation analysis and engineering application have proved that it has a better approximate effect and robustness than former algorithms.

7 Numerical smulation of evaporation and flow characteristics of gas FGD wastewater from a coal-fired power plant

PENG Geliang , TAN Zhiling , ZUO Beimeng , CHEN Quanxi , FU Jiangtao , YANG Bin , YANG Zhongqing

2018, 41(11):59-65. DOI: 10.11835/j.issn.1000-582X.2018.11.007

[Abstract](891) [HTML](392) [PDF 2.44 M](923)

Abstract:
It is an feasible way to realize the zero liquid discharge(ZLD) by using the waste heat from the flue gas of the coal-fired power plant to evaporate the spray of the FGD wastewater. In this paper, the evaporation and flow characteristics of atomized droplets in a high temperature flue of a 330 MW coal-fired power plant were studied by numerical simulation, and the droplet impinging condition at different atomizing mouth angles and the evaporation of droplets under different loads were investigated. The results show that in 50%,75% and 100% boiler load, the higher the temperature and the faster the speed of the flue gas, the less the time it takes for the complete evaporation of the droplets, and the maximum life time of droplet is between 2.85~3.36s. When the optimum atomization cone angle of a single flue structure is 65°, the size of vortex is inversely proportional to the distance between sprayer and the flue wall, which is conducive to the continuous diffusion of the local droplets from the nozzle region to other regions.

8 Design and implementation of compact dual-band rectenna for RF energy harvesting

ZHOU Xiaomeng , GUO Songtao

2018, 41(11):66-75. DOI: 10.11835/j.issn.1000-582X.2018.11.008

[Abstract](1120) [HTML](592) [PDF 12.79 M](1291)

Abstract:
A dual-band rectenna for radio frequency (RF) energy harvesting was proposed in view of the problem of low conversion efficiency of traditional dual-band rectenna. The rectenna is mainly composed of receiving antenna, an impedance matching circuit, a double voltage rectifier and a load circuit. Based on the miniaturized dual-band antenna, a new dual-band impedance matching network was introduced to improve the RF-DC conversion efficiency of the rectifier at a lower input power. In addition, the new impedance matching network reduces the complexity of the rectifier. Compared with traditional dual-band rectenna, the novel dual-band rectenna has higher RF-DC conversion efficiency in indoor environment for an incident power of -10dBm. The experimental results show that the RF-DC conversion efficiency reach 65.34% and 54.3% in 1.75GHz GSM band and 2.45GHz WLAN band, respectively. And the rectenna can be used in Internet of Things (IoT) low power devices.

9 An adaptive community detection method based on information transfer and density peaks

ZHAO Jianjun , WANG Qing , YOU Lei , HONG Wenxing

2018, 41(11):76-83. DOI: 10.11835/j.issn.1000-582X.2018.11.009

[Abstract](741) [HTML](690) [PDF 2.21 M](903)

Abstract:
Information transfer is the basic feature of the network. Accordingly, an adaptive community detection method based on information transfer and density peaks is proposed. Firstly, the trust degree function between nodes and neighbors is defined, and each node independently spreads amount of information to the network based on the trust degree. After the diffusion, the total information amount of the node is the density of the density peaks. The distance between the nodes in the network is replaced by the reciprocal of the information amount of the destination node. Then, a method is proposed that can automatically select core nodes which are divided into different communities, and the remaining nodes are allocated to the community of the closest core node. The algorithm has the advantage that no additional parameters are needed and the internal structure of the community can be found. The experimental results show that.

10 New method for gait recognition on combinability of multi-scale entropy and dynamic time warping algorithm

HE Shuqin , LIANG Xiyin , YAN Changlin , GUO Bei , LIU Hao

2018, 41(11):84-91. DOI: 10.11835/j.issn.1000-582X.2018.11.010

[Abstract](741) [HTML](424) [PDF 2.67 M](966)

Abstract:
In order to solve the problem of low accuracy of existing gait recognition, a method of gait recognition based on multi-scale entropy and DTW (dynamic time warping) algorithm is proposed. The new method for gait recognition adopts the camera and the high sampling rate sensor, and the acceleration sensor of the mobile phone is adopted to collect the data. The sensor works at the low sampling rate, and the normal walking acceleration data of 50 volunteers are collected and processed by multi-scale entropy, from which the entropy values at various scales are obtained. Finally, the DTW algorithm is used to match the multi-scale entropy. The simulation results show that the method based on the combination of multi-scale entropy and DTW improves the accuracy of identity recognition, and the EER(Equal Error Rate) is 13.7%, which provides a new idea for gait recognition.

11 Flower pollination algorithm with niche chaotic search strategy

CHEN Xicheng , LIU Shu , FAN Bingbing

2018, 41(11):92-99. DOI: 10.11835/j.issn.1000-582X.2018.11.011

[Abstract](609) [HTML](865) [PDF 1.16 M](1024)

Abstract:
In view of the limitations of Flower Pollination Algorithm (FPA) such as insufficient global convergence ability, low searching accuracy and premature maturity, a flower pollination algorithm using a niche chaotic search strategy was proposed. In order to increase the breadth of algorithm search, niche technology was applied to keep the diversity of the population and the global optimization ability of the algorithm was improved. The chaotic sequence generated by the logic self-mapping function was introduced to locally optimize the elites of the algorithm. The performance of the algorithm was tested by classic test functions. The results show that compared with Flower Pollination Algorithm, Differential Evolution(DE) and Bat Algorithm(BA), NCFPA has better global search ability and search accuracy.

12 Measurement of fluid surface velocities for river model using local features

ZHENG Jing , ZHANG Wei , LI Zhenghao , LIU Jiawei , TANG Yongliang , YANG Meiling

2018, 41(11):100-106. DOI: 10.11835/j.issn.1000-582X.2018.11.012

[Abstract](725) [HTML](391) [PDF 4.15 M](1139)

Abstract:
To handle the problems of complicated camera installation, low measurement accuracy and high measurement cost in conventional computer vision measurement methods of fluid surface velocity (FSV) of river models, a new method using local features was proposed. By this method cameras could be installed from a free angle of view without vertical downturn. Firstly throw scraps of paper as tracer particles on the surface. Then rectify the acquired video and reconstruct the aerial view to get the top view of FSV. Next use image matching method of local features to gain the dense velocity vector. Finally optimize FSV and output it. Experimental results show the velocity error of this method is less than 10% when the model velocity is between 0.01 m/s and 0.5 m/s and less than 5% when the model velocity is between 0.5 m/s and 1.5 m/s. In conclusion, this method outperforms the existing ones in terms of measurement accuracy, measurement cost and ease of use, and it has been applied in the analysis and measurement of large river models such as the Changhe section of Xiangjia Dam.

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