Experimental Study of Horizontal Gas-liquid Two-phase Flow in Two Medium-diameter Pipes and Prediction of Pressure Drop through BP Neural Networks

Wang Qinghua,Zou Honglan,Luo Wei,Yang Junzheng,Wen Xiaohong,Wang Yan 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.3

Horizontal gas-liquid two-phase flow is of crucial importance in oil-gas storage and transportation. In view of previous researches with the lack of horizontal gas-liquid two-phase flow in medium-diameter pipes (60-75 ㎜), experiments were conducted in DN 60 and DN75 at medium-high liquid velocity (50-250 m3/d) and high gas-liquid ratio (20-500 m3/m3). Comparison between flow patterns maps in DN60 and DN75 and the Taitel-Dukler model showed that only flow patterns map in DN60 agreed well. On the basis of experimental data analysis, variation laws of liquid holdup and pressure drop were determined. Besides, this paper developed a method to predict liquid holdup and pressure drop through BP neural networks. Results proved the capability of BP neural networks. The further validation can be made in practical applications.

Power Loss and Junction Temperature Analysis in the Modular Multilevel Converters for HVDC Transmission Systems

Wang, Haitian,Tang, Guangfu,He, Zhiyuan,Cao, Junzheng The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

The power loss of the controllable switches in modular multilevel converter (MMC) HVDC transmission systems is an important factor, which can determine the design of the operating junction temperatures. Due to the dc current component, the approximate calculation tool provided by the manufacturer of the switches cannot be used for the losses of the switches in the MMC. Based on the enabled probabilities of each SM in an arm, the current analytical models of the switches can be determined. The average and RMS currents can be obtained from the corresponding current analytical model. Then, the conduction losses can be calculated, and the switching losses of the switches can be estimated according to the upper limit of the switching frequency. Finally, the thermal resistance model of the switches can be utilized, and the junction temperatures can be estimated. A comparison between the calculation and PSCAD simulation results shows that the proposed method is effective for estimating the junction temperatures of the switches in the MMC.

Power Loss and Junction Temperature Analysis in the Modular Multilevel Converters for HVDC Transmission Systems

Haitian Wang,Guangfu Tang,Zhiyuan He,Junzheng Cao 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

The power loss of the controllable switches in modular multilevel converter (MMC) HVDC transmission systems is an important factor, which can determine the design of the operating junction temperatures. Due to the dc current component, the approximate calculation tool provided by the manufacturer of the switches cannot be used for the losses of the switches in the MMC. Based on the enabled probabilities of each SM in an arm, the current analytical models of the switches can be determined. The average and RMS currents can be obtained from the corresponding current analytical model. Then, the conduction losses can be calculated, and the switching losses of the switches can be estimated according to the upper limit of the switching frequency. Finally, the thermal resistance model of the switches can be utilized, and the junction temperatures can be estimated. A comparison between the calculation and PSCAD simulation results shows that the proposed method is effective for estimating the junction temperatures of the switches in the MMC.

Neural Approximation-based Model Predictive Tracking Control of Nonholonomic Wheel-legged Robots

Jiehao Li,Junzheng Wang,Shoukun Wang,Wen Qi,Longbin Zhang,Yingbai Hu,Hang Su 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.1

This paper proposes a neural approximation based model predictive control approach for tracking controlof a nonholonomic wheel-legged robot in complex environments, which features mechanical model uncertaintyand unknown disturbances. In order to guarantee the tracking performance of wheel-legged robots in an uncertainenvironment, effective approaches for reliable tracking control should be investigated with the consideration of thedisturbances, including internal-robot friction and external physical interactions in the robot’s dynamical system. In this paper, a radial basis function neural network (RBFNN) approximation based model predictive controller(NMPC) is designed and employed to improve the tracking performance for nonholonomic wheel-legged robots. Some demonstrations using a BIT-NAZA robot are performed to illustrate the performance of the proposed hybridcontrol strategy. The results indicate that the proposed methodology can achieve promising tracking performancein terms of accuracy and stability.

PDBNet: Parallel Dual Branch Network for Real-time Semantic Segmentation

Yingpeng Dai,Junzheng Wang,Jiehao Li,Jing Li 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.8

To make a trade-off between accuracy and inference speed in real-time applications on the unmanned mobile platform, a novel neural network, named Parallel Dual Branch Network (PDBNet), is proposed. Firstly, a multi-scale module, namely Parallel Dual Branch (PDB), is designed to extract complete information. PDB module consists of two parallel branches to remove detailed low-level information and high-level semantic information while maintaining few parameters. Then, based on the PDB module, PDBNet, a small-scale and shallow structure, is designed for semantic segmentation. A multi-scale module tends to extract abundant information and segment the object out from the image well. The small-scale and shallow structure tends to accelerate the inference speed. So PDBNet architecture is designed to be effective both in terms of accuracy and inference speed. PDBNet adopts three downsamplings to obtain feature maps with high spatial resolution and uses PDB modules with different dilation rates to extract multi-scale features and enlarge the receptive field in the last several layers. Finally, experiments on Camvid dataset and Cityscapes dataset, we respectively get 67.7% and 69.5% Mean Intersection over Union (MIoU) with only 1.82 million parameters and quicker speed on a single GTX 1070Ti card.

Shadow Lane Robust Detection by Image Signal Local Reconstruction

Du Mingfang,Wang Junzheng,Li Nan,Li Duoyang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.3

In order to resolve shadow interference and slow image processing speed in the visual navigation of unmanned vehicles on city roads, a new lane detection algorithm based on the Inverse Perspective Mapping(IPM) of vertical sub-image reconstruction using local bands was proposed. The lane’s IPM aerial image was obtained using the projective transformation of three-dimensional images of city roads. The ROI portion of the IPM map was decomposed and analyzed using the sym3 wavelet, and after analyzing and comparing the experimental results the first and second levels of the vertical sub images were selected for the reconstruction, compression, and removal of shadows from the original image. The Canny algorithm was proposed and adopted in order to extract the edge features of the reconstructed images according to real-time road image quality. A modified, polar angle, constraint-based, fast Hough transform was used to locate the candidate lanes. Finally, the main control point, straight-line-fitting algorithm was used to fit the final lanes, which achieved the precise location and recognition of the lane lines. The California Polytechnic lane data set, a public data platform, which is now widely used in road visual recognition fields around the world, was selected for the testing and verification of the algorithm. The results of the experiment and actual operation indicated that, despite having a storage space of approximately one tenth the size of similar algorithms, this detection algorithm effectively solves the issue of shadow removal, meets the real-time requirements of roadway image processing systems for unmanned vehicles with a recognition time of less than 20ms, and is robust.

Vibration isolation control performance for an innovative 3-DOF parallel stabilization platform

Shuo Jiang,Junzheng Wang,Shoukun Wang,Wei Shen 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

High vibration isolation performance of stabilization platforms for challenging terrain is strongly demanded in many fields, including material transportation, marine operation and airborne filming. In this study, we propose a 3-DOF parallel stabilization platform which can offset disturbance in vertical and horizontal directions. First, the overall design idea is explained, including system prototype, mechanical optimization design, and motion modeling. Then a force-position composite control framework based on active compliance is considered for impact cushioning under high frequency disturbance. Besides, an adaptive compliance control law fused with environmental stiffness online estimation and reference trajectory correction is designed to realize vibration isolation under variable excitations. Finally, simulations and experimental demonstrations using the developed 3-DOF stabilization platform are carried out. High vibration isolation performance shows the feasibility and effectiveness of proposed adaptive active compliance control strategy, which provides further applicability in engineering.

Fault-Tolerant Control Based on Modified eXogenous Kalman Filter for PMSM

Ma Liling,Wang Fuxiang,Shen Wei,Wang Junzheng 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

Aiming at the encoder fault of the three-phase permanent magnet synchronous motor control system, a modified eXogenous Kalman Filter (MXKF) is proposed. When there are errors in the initial state of the estimator, MXKF performs well while extended Kalman Filter leads to an unstable state of the system. For the system under the Three-phase Four-switch drive, MXKF is shown to have better fault-tolerant stability. In addition, to avoid the unexpected equilibrium points determined by the q-axis voltage equation, proper compensation is made in the filter. Finally, simulations have been done to verify the effectiveness of the proposed method in the following two cases: start-up with initial error and topology change of the drive. The results show the satisfying superiority of MXKF.

Bacillus daqingensis sp. nov., a Halophilic, Alkaliphilic Bacterium Isolated from Saline-Sodic Soil in Daqing, China

ShuangWang,Lei Sun,DanWei,Baoku Zhou,Junzheng Zhang,XuejiaGu,Lei Zhang,Ying Liu,Yidan Li,Wei Guo,Shuang Jiang,Yaqing Pan,Yufeng Wang 한국미생물학회 2014 The journal of microbiology Vol.52 No.7

An alkaliphilic, moderately halophilic, bacterium, designated strain X10-1T, was isolated from saline-alkaline soil in Daqing, Heilongjiang Province, China. Strain X10-1T was determined to be a Gram-positive aerobe with rod-shaped cells. The isolate was catalase-positive, oxidase-negative, non-motile, and capable of growth at salinities of 0–16% (w/v) NaCl (optimum, 3%). The pH range for growth was 7.5–11.0 (optimum, pH 10.0). The genomic DNA G+C content was 47.7 mol%. Its major isoprenoid quinone was MK-7 and its cellular fatty acid profile mainly consisted of anteiso-C15:0, anteiso-C17:0, iso-C15:0, C16:0, and iso-C16:0. The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol. Phylogenetic analysis based on 16S rRNA gene sequences showed that X10-1T is a member of the genus Bacillus, being most closely related to B. saliphilus DSM15402T (97.8% similarity) and B. agaradhaerens DSM 8721T (96.2%). DNA-DNA relatedness to the type strains of these species was less than 40%. On the basis of the phylogenetic, physiological, and biochemical data, strain X10-1T represents a novel species of the genus Bacillus, for which the name Bacillus daqingensis sp. nov. is proposed. The type strain is X10-1T (=NBRC 109404T =CGMCC 1.12295T).

Effects of Temperature, pH, and Relative Humidity on Growth of Penicillium expansum OM1 and its Patulin Production on Apple Puree Agar Medium

Haiyi Yu,Jeoung Gyu Lee,Wencai Zhao,Shengming Gao,Qing Chu,Shuxian Ma,Yidan Ji,Jinhuan Qu,Junzheng Wang,Liyuan Hao,Sung-Yong Hong,Ae-Son Om 한국식품영양과학회 2022 한국식품영양과학회 학술대회발표집 Vol.2022 No.10