Volume 43,Issue 5,2020 Table of Contents

1 Regulating ability analysis of distributed energy storage system based on fuzzy comprehensive evaluation

LI Ya , CHEN Minyou , LI Bo , DAI Ruihai , SHI Yizhi

2020, 43(5):1-10. DOI: 10.11835/j.issn.1000-582X.2019.002

[Abstract](576) [HTML](483) [PDF 1.91 M](1004)

Abstract:
Distributed energy storages play an important role in suppressing the fluctuation of intermittent power supply, participating in peak shaving,and improving power quality and power supply reliability. How to quantitatively evaluate the energy supply and regulation ability of energy storage system is very important for tapping the adjustment potential of various power and energy storage combination configurations and optimizing the allocation of distributed energy storage. In this paper, the response speed characteristics and power regulation characteristics of various energy storages are analyzed with respect to the commonly used energy storage forms and devices. With an analysis of various factors affecting the regulation capacity of energy storage systems, an evaluation model of regulation capacity of energy storages based on fuzzy comprehensive evaluation is proposed to quantitatively evaluate the energy supply and regulation performance of distributed energy storage system under the circumstances of different energy storage combination modes and different capacity allocation ratios,and its effectiveness is verified by simulation examples.

2 Metal foreign objects detection technology of MC-WPT system based on equivalent quality factor

WANG Saihao , DAI Xin , SHA Yunpeng , WANG Zhihui , QIAO Huijie

2020, 43(5):11-19. DOI: 10.11835/j.issn.1000-582X.2020.05.002

[Abstract](568) [HTML](477) [PDF 5.87 M](874)

Abstract:
The wireless power transfer technology has been gradually applied to various fields of production and life. When there are metal foreign objects between or around the power transmitter and the power receiver of the magnetic coupling wireless power transfer system, the transmission performance of the system is greatly affected, and even a safety hazard may occur. Aiming at the S/S type magnetic coupling wireless power transfer (MC-WPT) system, this paper proposes a non-ferromagnetic metal foreign object detection method based on equivalent quality factor, and gives the definition of equivalent quality factor. The equivalent quality factor model of S/S type MC-WPT system under ferromagnetic metal foreign objects, the principle and method of detecting metal foreign objects are expounded. Finally, the feasibility and effectiveness of the proposed metal foreign object detection method are verified by simulation and experiment.

3 Dual output power regulation method based on dynamic decoupling

OU Shifeng , XIAO Jing , ZHU Wenji , GAO Like , WU Lifang

2020, 43(5):20-30. DOI: 10.11835/j.issn.1000-582X.2020.202

[Abstract](494) [HTML](582) [PDF 4.81 M](989)

Abstract:
For the real-time and dynamic adjustment of output power for inductively coupled power transfer systems, a new power adjustment method based on dynamic decoupling technology is proposed. Two full-control switching tubes are added to the secondary side rectifier circuit of the wireless energy transmission system, and the switching between the switching tubes on both sides of the rectifier circuit is controlled, that is, the duty ratio of the two switching tubes is adjusted so that the load side and the resonant network are dynamically decoupled, thereby realizing the discontinuous adjustment of the output voltage of the resonant network and achieving the purpose of adjusting the output power. Compared with the four common power adjustment methods: frequency modulation, amplitude modulation, phase shifting and energy injection, the method proposed above has incomparable advantages in terms of speed, real-time, complexity, volume and cost. Finally, the correctness of the theoretical analysis and the feasibility of the scheme are verified by simulation and experiment.

4 Design of laser intelligent fire-fighting evacuation system based on ant colony algorithm

FENG Binbin , LI Li , BAI Yunchao , LI Congbo

2020, 43(5):31-39. DOI: 10.11835/j.issn.1000-582X.2020.05.004

[Abstract](569) [HTML](383) [PDF 5.41 M](1065)

Abstract:
For the problems of difficult identification, single guiding scheme, high maintenance cost and insufficient intellectualization in the current fire evacuation system in the harsh environment of fire smoke,an intelligent laser fire evacuation system based on ant colony algorithm is proposed, which is composed mainly of information acquisition module, central processing module and evacuation guidance module, so as to realize intelligent real-time monitoring and handling of fire situation. When a fire occurs, the sensors can dynamically collect fire information, and the displayers show where the fire occurs, as well as the optimal evacuation path by using ant a colony gorithm. Moreover, the evacuation guidance module projects the evacuation path on the ground in the form of laser relay to guide the dynamic evacuation of personnel.The feasibility and superiority of the system are verified with a case study.

5 Study on energy saving characteristics of variable temperature air supply under different ventilation modes

WANG Ye , BAI Yujie , YAN Ruowen

2020, 43(5):40-49. DOI: 10.11835/j.issn.1000-582X.2020.222

[Abstract](344) [HTML](593) [PDF 5.69 M](966)

Abstract:
Ventilation mode has important effect on indoor environmental quality and building operation energy consumption. Based on the unsteady heat transfer method, the thermal boundary conditions of building envelope are obtained. The ventilation effect and energy-saving characteristics of displacement ventilation and stratum ventilation in an office in cold zone are compared when the building envelope thermal properties meet the requirement of 65% energy saving. The results show that under the premise of thermal comfort, the air supply temperature range of displacement ventilation is 13.027.0 ℃ while that of stratum ventilation is 19.024.0 ℃. By changing the air supply temperature at different time, the daily average saving rate of mechanical refrigeration capacity of displacement ventilation and that of stratum ventilation can reach 2.87% and 5.16% respectively for fresh air treatment. And the indoor temperature of the displacement ventilation is more comfortable. The air supply volume under both ventilation modes decreases greatly compared with that corresponding to the basis air supply temperature, and the air supply saving rate is up to 22.65% and 32.14%, respectively. The indoor pollutant concentration under both ventilation modes is below the standard value. The research has important engineering guiding significance for further exploring the correlation between climatic conditions and ventilation modes, optimizing the design and operation management of air-conditioning systems.

6 Design and simulation of H∞ controller for industrial induction heating power supply

DANG Mingzhang , CAO Jiayong , LYU Wenzhuang , WU Yuchun

2020, 43(5):50-58. DOI: 10.11835/j.issn.1000-582X.2020.301

[Abstract](504) [HTML](824) [PDF 3.26 M](1014)

Abstract:
Induction heating has always been a hot topic for scholars domestic and overseas because of its advantages of environmental protection and high thermal efficiency. The disturbance which exists in the power and control circuits brings the difficulty of estimating the parameters of electrical components accurately. The performance of traditional PI controller based on deterministic model is difficult to improve. Therefore, it is necessary to consider the influence of the disturbance on the induction heating control system. In this paper, a system state space model with equivalent series resonant load was established, and the model was decoupled by linearization method. Based on the decoupled model, a double closed loop PI controller and an improved current inner loop H∞ controller were designed. Finally, the PI controller and the H∞ controller were simulated under two starting conditions respectively. It is further confirmed by comparison that the improved system has better anti-interference ability and dynamic characteristics.

7 Nonlinear damage identification of cracks of the concrete simply-supported bridge under operational environment

JIANG Yanfang , JIANG Wei , LIU Gang , ZHANG Heng

2020, 43(5):59-66. DOI: 10.11835/j.issn.1000-582X.2020.05.007

[Abstract](526) [HTML](488) [PDF 2.15 M](1000)

Abstract:
A non-linear damage detection method for cracks of the concrete simply-supported bridge based on the improved Hilbert-Huang transfer (HHT) is proposed in this work. The curvilinear breathing crack model controlled by curvature is employed to consider the breathing phenomenon of cracks, and the model is integrated into vehicle-bridge interaction system to simulate operational environment. The mirror extension and ensemble empirical mode decomposition algorithm are introduced to eliminate the end effect and mode mixing problems respectively. The energy time history from the acceleration response of the bridge under operational condition is acquired using the improved HHT algorithm, and then the appearance time and relative amplitude ratio from the peak of the energy time history are extracted as features to localize and quantify damage respectively. Numerical results show that the location and severity of the cracking damage can be successfully identified using only one sensor deployed on the bridge, which provides technical support to damage detection of cracks on the concrete simply-supported bridge.

8 Wind tunnel test of UHV transmission tower considering SSI interaction

CAI Qingqing , WU Haiyang , LIU Kun , LI Zhengliang , ZENG Jing

2020, 43(5):67-75. DOI: 10.11835/j.issn.1000-582X.2020.05.008

[Abstract](497) [HTML](461) [PDF 5.26 M](885)

Abstract:
In order to study the influence of transmission tower-foundation-bed coupling effect (SSI interaction) on wind-induced response of transmission tower under wind load, an UHV transmission tower-foundation-bed system is taken as an example to design its aeroelastic model according to discrete stiffness method with a rigid mass block used to simulate the foundation, and U-spring and damper used to simulate the bed to test the aeroelastic model in wind tunnel. The influence of foundation damping and stiffness on wind-induced response of transmission tower structure is also studied. The experimental results show that: 1) with SSI interaction taken into account, the vibration attenuation of the model is slower than that of the rigid foundation model; with the decrease of the foundation stiffness, the comprehensive stiffness of the model decreases and the natural vibration period increases; 2) the reduction of the foundation stiffness will gradually lead to greater displacement and acceleration response of the superstructure, but have little effect on the reaction force of the tower foot; with the increase of the foundation damping, the acceleration of the tower body decreases gradually, but the displacement and the reaction force of the tower foot almost remain unchanged. In conclusion, the influence of SSI interaction should be considered in the design of transmission tower structure.

9 Large slope deformation monitoring method based on pasted smart rock

JIANG Shenghua , SONG Yunhao , SUN Weihe , CHEN Huan , WANG Hao , YU Hao

2020, 43(5):76-83,92. DOI: 10.11835/j.issn.1000-582X.2020.05.009

[Abstract](482) [HTML](483) [PDF 4.42 M](711)

Abstract:
The existing slope deformation monitoring is often influenced by extreme harsh environment, difficult sensor layout and limited sensor range, etc. In this paper, the conception of pasted smart rock was put forward and a slope large deformation monitoring method using pasted smart rock was developed. Accordingly, the simplified algorithm of ultra-wide band (UWB) was given for the slope deformation monitoring method. The monitoring method was verified by landslide simulation system applied with driving force. The results show that the slope large deformation development and slope instability evaluation can by judged by pasted smart rock’s horizontal displacements, and the results are in accord with those of the monitoring assessment by soft film size. The proposed method can be used as reference in the further study and practical engineering monitoring.

10 Study on eccentric-loaded coefficients of cast-in-place box girder by solid FEM

CHANG Cheng

2020, 43(5):84-92. DOI: 10.11835/j.issn.1000-582X.2020.05.010

[Abstract](468) [HTML](837) [PDF 1.77 M](841)

Abstract:
The eccentric-loaded coefficients of more than 6 000 concrete cast-in-place box girders were analyzed by the secondary development of FEM software based on solid FEM,according to the relevant code of road and bridge. The results showed that the coefficient of eccentricity increased with the increase of the width-span ratio if the number of lanes was the same. It was found that the appropriate coefficient of a simply supported box girder could be taken from 1.15 to 1.5 and a formula was thus obtained to calculate the coefficient accurately. For the continuous box girder, the coefficient of each span could be solved by the above-mentioned formula, and revised according to the revised factor, with the maximum value taken as the coefficient of the bridge. The revised factor for the continuous box girder could be taken from 1.05 to 1.1. A larger correction coefficient was appropriate to select once the width-span ratio value was large or the span was far from the end of the beam, while a smaller one should be chosen on the contrary. In conclusion, this paper presented a batch method for establishing the solid FEM box girder model as well as its calculation and analysis processes.The method would be helpful in the study of the mechanical properties of the box girder, thus achieving a detailed and efficient design of it.

11 Indoor positioning algorithm based on TS-KNN

TIAN Zeyue , YU Xing , HUANG Jian

2020, 43(5):93-103. DOI: 10.11835/j.issn.1000-582X.2020.05.011

[Abstract](550) [HTML](1024) [PDF 4.99 M](912)

Abstract:
Indoor positioning is the hard demand of smart cities and many smart city-related applications are inseparable from location services. At present, the main indoor positioning technology includes Bluetooth, RFID, UWB and geomagnetic, etc., but due to such issues as cost, deployment convenience and so on, its applications development are limited. This paper proposes a KNN(K-Neatest Neighbor) localization algorithm based on fingerprint timing features (TS-KNN), which uses the fingerprint of the current moment to select the reference coordinates and the positioning results of the first few moments are used to perform weight correction for each reference coordinate. The experimental test results in a square in Chongqing show that the proposed TS-KNN method is superior to the KNN and the WKNN algorithms, since it can effectively improve the accuracy of indoor positioning and reduce the average positioning error.

12 Gas source location method based on extended set estimator

LU Yi , SHI Huayun

2020, 43(5):104-113. DOI: 10.11835/j.issn.1000-582X.2020.05.012

[Abstract](428) [HTML](609) [PDF 2.05 M](834)

Abstract:
This paper presents a distributed location method for indoor gas source based on extended set-membership filtering. Compared with the statistical estimation method based on stochastic model (extened Kalman filter and unscented Kalman filter), this kind of method only needs to know the boundary of the unknown noise, regardless of the randomness of the noise. The static turbulence model is utilized to calculate iteratively the positioning error boundary, and the actual value of the position state is effectively included in the estimation range, so that the positioning credibility can be achieved. Meanwhile, the least squares method is introduced to carry out the initial positioning to overcome the problem of initial point selection of the extended set membership filtering. Finally, indoor positioning simulation experiment based on the wireless electronic nose is conducted and the feasibility and validity of the proposed method are verified.

13 Mathematical model and its derivation in optimal risk portfolio

ZHOU Xiaohua , LI Chunhong , HUAN Gang

2020, 43(5):114-120. DOI: 10.11835/j.issn.1000-582X.2020.247

[Abstract](1050) [HTML](758) [PDF 1.34 M](1450)

Abstract:
In modern securities investment theories and methods, the optimal risk portfolio is one of the most important core concepts, but the existing literature lacks rigorous mathematical expression for this theory and its related conclusions. In order to solve this problem, we have studied the mathematical mechanism related to the formation of the concept of the optimal risk portfolio in portfolio selection and made strict logical deduction and mathematical modeling analysis. First of all, the mathematical analysis method was used to construct the corresponding relationship, that is, to establish one-to-one correspondence between the risk, the return of portfolio and the number pairs of plane coordinate system, and the algebraic method was employed to define an order relationship among these number pairs. From the perspective of analytic geometry and through the analysis of the intersection coordinates of quadric clusters, the mathematical equations that meet the relevant conditions of portfolio theory were constructed on the basis of the relevant properties of conic in two-dimensional plane, and then mathematical derivation and solution were carried out. Finally, by analyzing the mathematical model of the investment opportunity set of the binary portfolio, the mathematical expression of the optimal risk portfolio in the binary portfolio was determined. And this method can be extended to the case of multiple portfolio.

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