Wind pressure on a solar updraft tower in a simulated stationary thunderstorm downburst

Xinping Zhou,Fang Wang,Chi Liu 한국풍공학회 2012 Wind and Structures, An International Journal (WAS Vol.15 No.4

Thunderstorm downbursts are responsible for numerous structural failures around the world. The wind characteristics in thunderstorm downbursts containing vortex rings differ with those in 'traditional' boundary layer winds (BLW). This paper initially performs an unsteady-state simulation of the flow structure in a downburst (modelled as a impinging jet with its diameter being Djet) using a computational fluid dynamics (CFD) method, and then analyses the pressure distribution on a solar updraft tower (SUT) in the downburst. The pressure field shows agreement with other previous studies. An additional pair of low-pressure region and high-pressure region is observed due to a second vortex ring, besides a foregoing pair caused by a primary vortex ring. The evolutions of pressure coefficients at five orientations of two representative heights of the SUT in the downburst with time are investigated. Results show that pressure distribution changes over a wide range when the vortices are close to the SUT. Furthermore, the fluctuations of external static pressure distribution for the SUT case 1 (i.e., radial distance from a location to jet center x=Djet) with height are more intense due to the down striking of the vortex flow compared to those for the SUT case 2 (x=2Djet). The static wind loads at heights z/H higher than 0.3 will be negligible when the vortex ring is far away from the SUT. The inverted wind load cases will occur when vortex is passing through the SUT except on the side faces. This can induce complex dynamic response of the SUT.

Adaptive neural network sliding mode control for serially connected hydraulic cylinders of a heavy-duty hydraulic manipulator

Xinping Guo,Hengsheng Wang,Liang Wang,Hua Liu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7

A sliding mode control based on adaptive neural network is proposed aiming at the automatic control problem of the heavy-duty hydraulic manipulator, which is widely applied in construction machinery. The simplified state space model is established for the two hydraulic cylinders connected in series for the parallel movement of the boom of a rock drilling jumbo manipulator. By using the square of the norm of the neural network weight vector to replace the elements of the weight vector as the adaptive parameter, the computational burden of the controller is reduced and hence becomes more suitable for practical applications. The control law is designed by combining adaptive neural network with sliding mode control, and Lyapunov stability analysis is performed theoretically for the proposed control algorithm. Simulations are conducted to verify the feasibility of the designed controller. Extensive experimental studies are carried out on the heavy-duty hydraulic manipulator of a rock drilling jumbo. When tracking sinusoidal position, the error of the proposed controller is reduced by 53 % and 71 % compared with the traditional sliding mode controller and PID controller, respectively, thereby proving the effectiveness and practicality of the proposed control algorithm.

Wind pressure on a solar updraft tower in a simulated stationary thunderstorm downburst

Zhou, Xinping,Wang, Fang,Liu, Chi Techno-Press 2012 Wind and Structures, An International Journal (WAS Vol.15 No.4

Thunderstorm downbursts are responsible for numerous structural failures around the world. The wind characteristics in thunderstorm downbursts containing vortex rings differ with those in 'traditional' boundary layer winds (BLW). This paper initially performs an unsteady-state simulation of the flow structure in a downburst (modelled as a impinging jet with its diameter being $D_{jet}$) using a computational fluid dynamics (CFD) method, and then analyses the pressure distribution on a solar updraft tower (SUT) in the downburst. The pressure field shows agreement with other previous studies. An additional pair of low-pressure region and high-pressure region is observed due to a second vortex ring, besides a foregoing pair caused by a primary vortex ring. The evolutions of pressure coefficients at five orientations of two representative heights of the SUT in the downburst with time are investigated. Results show that pressure distribution changes over a wide range when the vortices are close to the SUT. Furthermore, the fluctuations of external static pressure distribution for the SUT case 1 (i.e., radial distance from a location to jet center x=$D_{jet}$) with height are more intense due to the down striking of the vortex flow compared to those for the SUT case 2 (x=$2D_{jet}$). The static wind loads at heights z/H higher than 0.3 will be negligible when the vortex ring is far away from the SUT. The inverted wind load cases will occur when vortex is passing through the SUT except on the side faces. This can induce complex dynamic response of the SUT.

High step-up three-level DC-DC converter with three-winding coupled-inductor

Ding, Xinping,Zhao, Delin,Liu, Yun,Li, Kai,Hao, Yangyang The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1

Due to the wide adoption of photovoltaic power generation, non-isolated high step-up DC-DC converters are becoming more and more popular. Among these converters, the switched/coupled-inductor-based converter is more attractive due to the fact that it has fewer power devices and a high efficiency. This paper presents a three-level high step-up DC-DC topology with a three-winding coupled-inductor. When compared with a conventional switched/coupled-inductor-based converter, a higher efficiency can be achieved, owing to low voltage stresses devices, fewer semiconductors in the power loop, lower current stresses, and ZCS of the main switches. The operating principle of the proposed topology is analyzed in detail via equivalent circuits, where a theoretical analysis is carried out using state space modelling. Experimental results obtained on a 24-300 V, 360 W lab prototype have verified the excellent performance of the proposed DC-DC converter.

Glass fiber reinforced graphite/carbon black@PES composite films for high-temperature electric heaters

Yaning Liu,Zhen Xiao,Wenkui Zhang,Hui Huang,Jun Zhang,Yongping Gan,Xinping He,Bingjia Wang,Yi Han,Yang Xia 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.107 No.-

Carbon based conductive polymer composites as electrothermal materials offers many merits in highflexibility, light weight, low cost, excellent processability, and rapid heating ability, however, the maximumworking temperature is usually lower than 200 C, hampering seriously the medium–high temperatureapplications. Herein, a series of rationally designed glass fiber reinforced graphite/carbonblack@polyethersulfone (G/CB@PES) composites are developed to significantly promote the maximumworking temperature over 300 C. To be specific, the introduced glass fibers acted as rigid skeleton greatlyenhance the mechanical strength of PES polymer matrix, thereby offering robust structural stability inhigh temperature working scenario. Meanwhile, glass fibers not only endow G/CB@PES composite withexcellent flame-retardant ability, but also provide rapid thermal conduction channels to reduce the riskof heat accumulation and overheating. More importantly, glass fiber reinforced G/CB@PES composites aselectrothermal film heaters exhibit superior electric heating performance in terms of fast temperatureresponsiveness, high electric heating efficiency, stable maximum working temperatures, and high electricpower efficiency under the relatively low applied voltages of 3–21 V. This work provides new insights onthe innovative design and facile fabrication of high working temperature electrothermal film heaters inemerging applications.

Overexpression of NPC1L1 in the livers of transgenic Bama miniature pigs accelerates lipid peroxidation

Chongli Xu,Yu Liu,Yuchen Gong,Xinping Duan,Xiaochun Tang,Mingjun Zhang,Daxin Pang,Liqing Yu,Hongwei Zhao,Hongsheng Ouyang 한국유전학회 2015 Genes & Genomics Vol.37 No.2

Although Niemann-Pick C1-Like 1 (NPC1L1)plays a key role in intestinal cholesterol absorption, regulatingcholesterol metabolism and maintaining cholesterolmetabolic homeostasis, the molecular mechanism ofNPC1L1 in lipid-metabolism disorders leading to liverdisease remains largely unknown. Previous studies haveshown that NPC1L1 is related with the development offatty liver. Therefore, we hypothesized that NPC1L1 playsan important role in lipid-metabolism disorders and liverdisease by affecting the transcription of certain genesinvolved in lipid synthesis. To further elucidate the functionof NPC1L1, especially in the liver, we used somaticcellnuclear transfer to establish transgenic pigs thatexpressed human NPC1L1 in their livers. We investigatedsuperoxide dismutase activities and the levels of free fattyacids and malondialdehyde, a biomarker of lipid peroxidation. Superoxide dismutase activities significantlydecreased, and free fatty acid and malondialdehyde levelssignificantly increased in the NPC1L1 transgenic pigs,indicating that the overexpression of NPC1L1 in the liverresulted in severe lipid peroxidation. Our findings suggestthat NPC1L1 plays an important role in lipid-metabolismdisorders and liver disease.

COMPUTER VISION FOR AUTOMATIC RECOGNITION OF VEHICLE LICENSE PLATES

Zhongsheng Jin,Tianyu Liu,Tiejun Dong,Xinping Xu 대한전자공학회 1991 ICEIC:International Conference on Electronics, Inf Vol.1991 No.8

Characterization of Interphase Microbial Community in Luzhou-Flavored Liquor Manufacturing Pits of Various Ages by Polyphasic Detection Methods

( Hui Li ),( Jun Huang ),( Xinping Liu ),( Rongqing Zhou ),( Xiaofei Ding ),( Qianyin Xiang ),( Liqiang Zhang ),( Chongde Wu ) 한국미생물 · 생명공학회 2017 Journal of microbiology and biotechnology Vol.27 No.1

It is vital to understand the changing characteristics of interphase microbial communities and interspecies synergism during the fermentation of Chinese liquors. In this study, microbial communities in the three indispensable phases (pit mud, zaopei, and huangshui) of Luzhou-flavored liquor manufacturing pits and their shifts during cellars use were first investigated by polyphasic culture-independent approaches. The archaeal and eubacterial communities in the three phases were quantitatively assessed by combined phospholipid ether lipids/ phospholipid fatty acid analysis and fluorescence in situ hybridization. In addition, qualitative information regarding the microbial community was analyzed by PCR-denaturing gradient gel electrophoresis. Results suggested that the interphase microbial community profiles were quite different, and the proportions of specific microbial groups evolved gradually. Anaerobic bacteria and gram-positive bacteria were dominant and their numbers were higher in pit mud (10⁹ cells/g) than in huangshui (10⁷ cells/ml) and zaopei (10⁷cells/g). Hydrogenotrophic methanogenic archaea were the dominant archaea, and their proportions were virtually unchanged in pit mud (around 65%), whereas they first increased and then decreased in zaopei (59%-82%-47%) and increased with pit age in huangshui (82%-92%). Interactions between microbial communities, especially between eubacteria and methanogens, played a key role in the formation of favorable niches for liquor fermentation. Furthermore, daqu (an essential saccharifying and fermentative agent) and metabolic regulation parameters greatly affected the microbial community.

Determining a Key Service Area of Feeder Buses for Rail Transit Station Based on Potential Railway Demand

Xiaohua Yu,Yaru Bi,Peng Chen,Xinping Liu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.12

As the size of the city expands, longer journeys often involve the use of two or more modes of transportation. Feeder buses perform as a feeder mode of rail transit, its feeder areas are the key factor to improve this bus-rail transit mode service quality. Feeder areas that are either too small or too large can hinder the effectiveness of feeder buses. This paper presents a method to determine a suitable range as the key service of feeder buses for rail transit stations. The modal of accessibility consistency threshold interface of bus and bus-rail transit mode features is established, and the competition area of adjacent stations is considered to calculate the reasonable bus feeder range of rail transit stations. Based on the analysis of the demand characteristics of the feeder passengers, the potential passengers of the bus-rail transit travel mode are defined as the travel where only one endpoint of the starting and ending is within the walking range of the rail transit station, and a method for identifying the points of interest of potential passengers of the bus-rail transit mode is proposed. The potential passenger flow within the reasonable feeder range of rail transit stations is visualized, and the key service areas of feeder buses are determined based on the maximum potential passengers. Taking Jinan Metro Line NO.2 Stations as an example, combined with the station type, the key service area of feeder buses for railway stations is explained.

Carbon molecular sieves from soybean straw-based activated carbon for CO2/CH4 separation

Yuxian Xu,Xiaochuan Chen,Dan Wu,Yongjin Luo,Xinping Liu,Qingrong Qian,Liren Xiao,Qinghua Chen 한국탄소학회 2018 Carbon Letters Vol.25 No.-

Soybean straw (SS)-based activated carbon was employed as a precursor to prepare carbon molecular sieves (CMSs) via chemical vapor deposition (CVD) technique using methane as carbon source. Prior to the CVD process, SS was activated by 0.5 wt% ZnCl2, followed by a carbonization at 500°C for 1 h in N2 atmosphere. N2 (77 K) adsorption-desorption and CO2 (273 K) adsorption tests were carried out to analyze the pore structure of the prepared CMSs. The results show that increasing the deposition temperature, time or methane flow rate leads the decrease in N2 adsorption capacity, micropore volume and average pore diameter of CMSs. The adsorption selectivity coefficient of CO2/CH4 achieves as high as 20.8 over CMSs obtained under the methane flow rate of 30 mL min–1 at 800°C for 70 min. The study demonstrates the prepared CMSs are a candidate adsorbent for CO2/CH4 separation.