http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Hongpeng (검색결과 34 건)
- 무료
- 기관 내 무료
- 유료
-
-
-
A New Method based on Centrifuge Model Test for Evaluating Ground Settlement Induced by Tunneling
Hongpeng Lai,Jian Zhang,Lianyang Zhang,Rui Chen,Wanjing Yang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6
Current methods for evaluating the ground settlement due to tunneling in loess do not fully consider the special engineering properties of loess. This paper first studied the ground settlement due to tunnel construction in loess by conducting a uniquely designed centrifuge model test. Then the ground settlements were calculated using a currently widely used method and compared with the measured values from the centrifuge model test. The results indicated a substantial difference between the calculated and measured settlement profiles. For the stratum at shallow depth, the calculated settlement profiles were flatter with smaller maximum settlement Smax at the tunnel centerline and larger settlement far from the centerline than those from the centrifuge model test; while for the stratum near the tunnel crown, the opposite was obtained. The main reason for the difference is because of the large void structure and high compressibility of loess which causes additional settlement at shallow depth. Based on the centrifuge model test results, a new method which properly considers the special engineering characteristics of loess was proposed to evaluate the settlement due to tunnel construction in loess. The calculated settlement profiles using the new method were in good agreement with those from the centrifuge model test. Finally, the new method was used to evaluate the ground settlement caused by the construction of a Metro tunnel in loess and satisfactory results were obtained.
-
A Modified Single-Phase Transformerless Z-Source Photovoltaic Grid-Connected Inverter
Hongpeng Liu,Guihua Liu,Yan Ran,Gaolin Wang,Wei Wang,Dianguo Xu 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5
In a grid-connected photovoltaic (PV) system, the traditional Z-source inverter uses a low frequency transformer to ensure galvanic isolation between the grid and the PV system. In order to combine the advantages of both Z-source inverters and transformerless PV inverters, this paper presents a modified single-phase transformerless Z-source PV grid-connected inverter and a corresponding PWM strategy to eliminate the ground leakage current. By utilizing two reversed-biased diodes, the path for the leakage current is blocked during the shoot-through state. Meanwhile, by turning off an additional switch, the PV array is decoupled from the grid during the freewheeling state. In this paper, the operation principle, PWM strategy and common-mode (CM) characteristic of the modified transformerless Z-source inverter are illustrated. Furthermore, the influence of the junction capacitances of the power switches is analyzed in detail. The total losses of the main electrical components are evaluated and compared. Finally, a theoretical analysis is presented and corroborated by experimental results from a 1-kW laboratory prototype.
-
Hongpeng Zheng,Yulong Lei,Pengxiang Song 한국자동차공학회 2017 International journal of automotive technology Vol.18 No.3
Hydraulic retarders are auxiliary braking devices that reduce the velocity of a vehicle, particularly when a vehicle is driven downhill. Such velocity reduction could reduce the potential risk caused by brake failure caused by the service brake working for a long time and the temperature of the brake shoe becomes extremely high. This paper introduces the construction of the hydraulic retarder and proposes two mathematical models for the hydraulic retarder. The first mathematical model is deduced by using fluid mechanics, which is used to analyze the mechanism of how braking torque is produced and the key factors that can influence the value of the braking torque. The second mathematical model is deduced by using thermodynamics, which is used to quantify the heat produced by the hydraulic retarder. This research emphasizes that the flow rate and the average velocity of the working fluid in the working chamber mainly determine the braking torque of the hydraulic retarder. The flow rate into and out of the working chamber determines the temperature rise of the working fluid. Computational fluid dynamics (CFD) simulations are conducted with the Reynolds-averaged Navier-Stokes (RANS) and Shear Stress Transport (SST) turbulent models. Experiments are carried out to justify the two mathematical models and the CFD simulations. The results show that the mathematical models are capable of describing the force analysis and energy conversion of the hydraulic retarder and SST is more accurate for CFD simulation and the error is within 6 %.
-
Hongpeng Lai,Tengteng Wang,Zuo Kang,Rui Chen,Qiuyang Hong 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.7
As an increasing number of metro lines have been planned or executed in urban area, new tunnel undercrossing existing tunnels has been commonly practiced. Construction of the existing tunnel causes disturbance to the surrounding soil and hence affects the operational parameters of undercrossing tunneling especially the chamber pressure of EPB machine. However, very limited research studies this effect. To fill the gap of knowledge, this paper proposed a new method for calculating the chamber pressure of EPB tunneling machine in undercrossing project. First, the effect of existing tunnel on surrounding soil is classified as removal-and-replacement effect, excavation-induced-disturbance effect, and elastic foundation beam effect. Second, based on analysis of the mutual interaction between existing tunnel and the undercrossing tunneling, three zones have been identified to study the chamber pressure of EPB machine. Next, a new method is proposed to calculate the chamber pressure in the process of undercrossing existing tunnel. Finally, the proposed method has been verified with measured data from two engineering cases. The comparison results show that the proposed method is in good agreement with the measured data, indicating that it is reasonable with high accuracy.
-
Research on a New Method based on Improved ACO Algorithm and SVM Model for Data Classification
Hongpeng Zhu,Xiaohong Li 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.1
Because the properties of data are becoming more and more complex, the traditional data classification is difficult to realize the data classification according to the complexity characteristic of the data. Support vector machine is a machine learning method with the good generalization ability and prediction accuracy. So an improved ant colony optimization(ACO) algorithm is introduced into the support vector machine(SVM) model in order to propose a new data classification(ERURACO-SVM) method. In the ERURACO-SVM method, the pheromone evaporation rate strategy and pheromone updating rule are introduced into the ACO algorithm to improve the optimization performance of the ACO algorithm, and then the parallelism, global optimization ability, positive feedback mechanism and strong robustness of the improved ACO algorithm is used to find the optimal combination of parameters of the SVM model in order to improve the learning performance and generalization ability of the SVM model and establish the optimal data classification model. Finally, the experimental data from the UCI machine learning database are selected to validate the classification correctness of the ERURACO-SVM method. The experiment results show that the improved ACO(ERURACO) algorithm has better optimization performance for parameters selection of the SVM model and the ERURACO-SVM method has higher classification accuracy and better generalization ability.
-
Droop Control Scheme of a Three-phase Inverter for Grid Voltage Unbalance Compensation
Hongpeng Liu,Jiajie Zhou,Wei Wang,Dianguo Xu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4
The stability of a grid-connected system (GCS) has become a critical issue with the increasing utilization of renewable energy sources. Under grid faults, however, a grid-connected inverter cannot work efficiently by using only the traditional droop control. In addition, the unbalance factor of voltage/current at the common coupling point (PCC) may increase significantly. To ensure the stable operation of a GCS under grid faults, the capability to compensate for grid imbalance should be integrated. To solve the aforementioned problem, an improved voltage-type grid-connected control strategy is proposed in this study. A negative sequence conductance compensation loop based on a positive sequence power droop control is added to maintain PCC voltage balance and reduce grid current imbalance, thereby meeting PCC power quality requirements. Moreover, a stable analysis is presented based on the small signal model. Simulation and experimental results verify the aforementioned expectations, and consequently, the effectiveness of the proposed control scheme.
-
-
A Modified Single-Phase Transformerless Z-Source Photovoltaic Grid-Connected Inverter
Liu, Hongpeng,Liu, Guihua,Ran, Yan,Wang, Gaolin,Wang, Wei,Xu, Dianguo The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5
In a grid-connected photovoltaic (PV) system, the traditional Z-source inverter uses a low frequency transformer to ensure galvanic isolation between the grid and the PV system. In order to combine the advantages of both Z-source inverters and transformerless PV inverters, this paper presents a modified single-phase transformerless Z-source PV grid-connected inverter and a corresponding PWM strategy to eliminate the ground leakage current. By utilizing two reversed-biased diodes, the path for the leakage current is blocked during the shoot-through state. Meanwhile, by turning off an additional switch, the PV array is decoupled from the grid during the freewheeling state. In this paper, the operation principle, PWM strategy and common-mode (CM) characteristic of the modified transformerless Z-source inverter are illustrated. Furthermore, the influence of the junction capacitances of the power switches is analyzed in detail. The total losses of the main electrical components are evaluated and compared. Finally, a theoretical analysis is presented and corroborated by experimental results from a 1-kW laboratory prototype.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
