检索结果-南通市图书馆

Computational study of bubbly jets in stagnant water

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2019年第5期31卷 1021-1033页

作者： Yan-xu Wang Ze-gao Yin Wenming Zhang David ZZhu engineering college Ocean University of ChinaQingdao 266100China Shandong Province Key Laboratory of Ocean engineering Ocean University of ChinaQingdao 266100China Water Resources engineer City of EdmontonEdmontonABCanada Department of Civil and Environmental engineering University of AlbertaEdmontonABCanada

The air-water bubbly jets in a stagnant water are numerically investigated by using a CFD software package with the realizable k-e turbulence *** focus is on the jet evolutionary behaviors in terms of the gas void fraction,the axial water velocity,the turbulent kinetic energy(TKE),the entrainment coefficient,and the momentum and buoyancy fluxes in a wide range of the bubbly jets(with the initial gas volume fractions ranging from 0 to 0.83).The computational results are found generally in good agreement with the experimental results reported in the *** the gas void fraction and the axial water velocity follow the Gaussian distribution in the radial direction as expected,however a double-peak distribution is found for the TKE at some distance away from the *** the increase of the longitudinal distance,their peak values generally are decreased until reaching approximately their terminal *** non-dimensional relations are revealed in both the radial and longitudinal *** potential core and the spreading rates of the bubbly jets are then *** liquid volume flux of the bubbly jets is found to increase almost linearly along the centerline with an entrainment coefficient of *** momentum flux of the bubbly jets increases due to the buoyancy force,and the relative importance of the momentum and buoyancy fluxes is also discussed.

关键词： Bubbly jet gas void fraction axial water velocity turbulent kinetic energy(TKE) flux

Design and test of 4ZZ-4A2 full-hydraulic self-propelled jujube harvester

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological engineering 2018年第4期11卷 104-110页

作者： Wei Fu Zhiyuan Zhang Kai Ding Weibin Cao Za Kan Junbing Pan Yudong Liu college of Mechanical and Electrical engineering Shihezi UniversityShihezi 832003XinjiangChina Agricultural Machinery Key Laboratory of Xinjiang Production and Construction corps Shihezi 832003XinjiangChina

The cultivated area of jujube in Xinjiang has increased rapidly in recent *** the jujube harvest by hand has the shortage of high labor intensity,low efficiency and high labor cost,in addition,the harvesting machinery applying to dwarf and dense planting mode of jujubes is unavailable in *** 4ZZ-4A2 based on the full-hydraulic self-propelled jujube harvester was designed to solve the above *** harvester was mainly composed of a frame,a vibrating device,a jujube collecting and conveying device,an air separation device,a steering system,a hydraulic system and a jujube suction device and was capable of completing vibration,collection,conveying,cleaning and sundries removal work of jujubes through one *** jujubes dropped on the ground were picked up at the same *** AMESim simulation software was adopted to perform simulation analysis on the overall hydraulic *** results showed that the speed of the vibrating motor was stable at about 650 r/min(the corresponding vibration frequency is 10.83 Hz)with the torque of 80 N·m,the speed of the conveyor motor was stable at 77 r/min with the torque of 77 N·m;the speed of the fan motor was stable at 54 r/min with the torque of 53.6 N·m;the speed of the walking motor fluctuated around 100 r/min with the torque of about 1000 N·m;the hydraulic steering system responded rapidly and could satisfy the actual working requirements of the jujube *** jujube garden test results showed that the harvester could reach to the optimum harvesting effect when running at the speed of 0.5 m/*** such speed,the ground jujube picking rate was 45.1%,the tree jujube harvesting rate was 93.2%,the loss rate was 2.9%,and the damage rate was 0.9%.This study can provide theoretical basis and technical support for the jujube harvester.

关键词： harvester jujube hydraulic simulation dwarf and close planting design

The cycloaddition reaction using visible light photoredox catalysis

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2016年第2期59卷 161-170页

作者： Yu Liu Renjie Song Jinheng Li Department of Chemistry and Chemical engineering Hunan Institute of Science and TechnologyYueyang 414005China State Key Laboratory of Chemo/Biosensing and Chemometrics College of Chemistry and Chemical Engineer ingHunan UniversityChangsha 410082China

In recent years, visible light photoredox catalysis has emerged as an important research area in synthesis. In this review, we describe the recent progress in the visible light induced cycloaddition reactions, including [2+2], [3+2], [4+2] and [2+2+2] cycloadditions, for the construction of four-, five- or six-membered cycles and polycycles. Furthermore, the mechanisms for these transformations are also discussed, in which the formation of the radicals is initiated by a visible light photoredox catalysis process.

关键词： cycloaddition annulation visible light photoredox

Acceleration of the particulate organic matter hydrolysis by start-up stage recovery and its original microbial mechanism

在线全文

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & engineering 2021年第1期15卷 175-184页

作者： Yanqing Duan Aijuan Zhou Xiuping Yue Zhichun Zhang Yanjuan Gao Yanhong Luo Xiao Zhang college of Environmental Science and engineering Taiyuan University of TechnologyTaiyuan 030024China Shanxi engineer Research Institute of Sludge Disposition and Resources Taiyuan University of TechnologyTaiyuan 030024China School of Environment and Safety engineering North University of ChinaTaiyuan 030051China

To address the availability of carbon sources for denitrification,the accelerated hydrolysis of the most abundant but low-availability fraction of particulate organic matter(POM)was *** sieves with different pore sizes were used as primary pretreatment at the start-up-stage of the biological process to separate some POM from the liquid *** changes in soluble carbohydrates and proteins were monitored to investigate the hydrolysis performance of the sieved POM,with waste activated sludge(WAS)as the control *** results showed that an average of 35%POM could be entrapped before filtrate mat *** addition,benefiting from the high polysaccharides concentration,as well as the high availability due to the relatively loose physical structure,a 23%hydrolysis efficiency of POM was obtained,in contrast to that of WAS(3.4%),with a hydrolysis constant of 0.39 h^(−1).The prominent performance was also attributed to the unique microbial communities having been domesticated at a lower temperature,especially the cellulose-degrading bacteria Paraclostridium and psychrophile Psychrobacter,making up 6.94%and 2.56%,***,the potential benefits and application of improved POM hydrolysis by start-up stage recovery via mesh sieves combined with anaerobic fermentation were evaluated,including selective POM entrapment,alleviation of blockage and wear,and a reduction in aeration *** the proposed strategy,carbon availability for biological nutrient removal(BNR)processes is anticipated to be improved more economically than that can be achieved by primary clarifier elimination.

关键词： Particulate organic matter(POM) Hydrolysis Microbial community Mass balance

Effect of Tension on Friction Coefficient Between Lining and Wire Rope with Low Speed Sliding

在线全文

学校读者我要写书评

暂无评论

Journal of China University of Mining and Technology 2007年第3期17卷 409-413页

作者： PENG Yu-xing ZHU Zhen-cai CHEN Guo-an CAO Guo-hua School of Mechanical and Electrical engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China PLA engineer Command college Xuzhou Jiangsu 221004 China

In order to obtain the exact friction coefficient between lining and wire rope, the tension of wire rope is studied as a factor which affects this coefficient. A mechanical model of a wire rope subjected to axial load was established to determine the torque of the wire rope. The contact motion between lining and wire rope was regarded as a screw rotation and the axial force of the lining resulting from the torque of the wire rope was analyzed. Theoretical formulas relating tension of the wire rope and the friction coefficient was obtained. Experiments between lining and wire rope with low sliding speed were carried out with friction tester made by us. Experimental results show that increment of the friction coefficient is proportional to that of the tension of the wire rope with a low sliding speed. The experimental results agree with the theoretical calculation; the errors are less than 6%, which oroves the validity of the theoretical model.

关键词： wire rope tension lining friction coefficient low speed

Theoretical Analysis and Experimental Verification on Valve-less Piezoelectric Pump with Hemisphere-segment Bluff-body

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical engineering 2014年第3期27卷 595-605页

作者： JI Jing ZHANG Jianhui XIA Qixiao WANG Shouyin HUANG Jun ZHAO Chunsheng State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics college of Mechanical and Electrical engineering Qingdao Agricultural University college of Mechanical and Electronic engineer Beijing Union University Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences

Existing researches on no-moving part valves in valve-less piezoelectric pumps mainly concentrate on pipeline valves and chamber bottom valves, which leads to the complex structure and manufacturing process of pump channel and chamber bottom. Furthermore, position fixed valves with respect to the inlet and outlet also makes the adjustability and controllability of flow rate worse. In order to overcome these shortcomings, this paper puts forward a novel implantable structure of valve-less piezoelectric pump with hemisphere-segments in the pump chamber. Based on the theory of flow around bluff-body, the flow resistance on the spherical and round surface of hemisphere-segment is different when fluid flows through, and the macroscopic flow resistance differences thus formed are also different. A novel valve-less piezoelectric pump with hemisphere-segment bluff-body （HSBB） is presented and designed. HSBB is the no-moving part valve. By the method of volume and momentum comparison, the stress on the bluff-body in the pump chamber is analyzed. The essential reason of unidirectional fluid pumping is expounded, and the flow rate formula is obtained. To verify the theory, a prototype is produced. By using the prototype, experimental research on the relationship between flow rate, pressure difference, voltage, and frequency has been carried out, which proves the correctness of the above theory. This prototype has six hemisphere-segments in the chamber filled with water, and the effective diameter of the piezoelectric bimorph is 30mm. The experiment result shows that the flow rate can reach 0.50 mL/s at the frequency of 6 Hz and the voltage of 110 V. Besides, the pressure difference can reach 26.2 mm H20 at the frequency of 6 Hz and the voltage of 160 V. This research proposes a valve-less piezoelectric pump with hemisphere-segment bluff-body, and its validity and feasibility is verified through theoretical analysis and experiment.

关键词： valve-less piezoelectric pump hemisphere-segment bluff-body flow resistance

Theoretical analysis of thermoviscoelastic contact between friction lining and wire rope in mine friction hoists

在线全文

学校读者我要写书评

暂无评论

Mining Science and Technology 2009年第4期19卷 518-521页

作者： PENG Yu-xing ZHU Zhen-cai CHEN Guo-an School of Mechanical and Electrical engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China PLA engineer Command college Xuzhou Jiangsu 221004 China

Serious accidents of mine hoists caused by high-speed sliding between friction lining and wire rope are often seen in coal *** order to solve this problem,we analyzed the contact characteristics between friction lining and wire *** we carried out a dynamic mechanical analysis(DMA) to explain the change in mechanical properties of the friction lining as function of temperature and load frequency and found that temperature has a stronger effect on the mechanical properties than the *** used multiple regression analysis to obtain the thermoviscoelastic constitutive relations of the friction *** well we derived the analytic solution for the thermoviscoelastic contact radius and pressure by combining the theory of viscoelastic contact mechanics with thermoviscoelastic constitutive relations.

关键词： contact mechanics thermoviscoelasticity friction lining dynamic mechanical analysis mine hoist

Erosion rate of sand and mud mixtures

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2020年第6期35卷 563-575页

作者： Chamil Perera Jarrell Smith Weiming Wu David Perkey Anthony Priestas Department of Civil and Environmental engineering Clarkson University Coastal and Hydraulics Laboratory US Army Corps of Engineers

Erosion of mixed cohesive and noncohesive sediments is studied using the erosion test instrument *** sediment mixtures are composed of well-sorted quartz sand(0.25-0.5 mm) and one of the three used muds:kaolinite,kaolinite-bentonite and Mississippi River *** mud contents cover from 0 to 100%.The measured data of erosion rate and bed shear stress are used to examine the segmented linear,nonlinear,and exponential erosion *** parameters of each erosion model are related to the physical properties of sediment mixtures,including clay fraction,mud fraction,mixture dry density,and mud dry *** is found that the three models can fit well with the data,and their parameters have strong relations with the mud fraction and mud dry density,to a less extent with the clay fraction,but not with the mixture dry density.

关键词： Cohesive sediments Noncohesive sediments Sand and mud mixtures Segmented linear model Nonlinear model Exponential model

Design and Implementation of Training Simulator for Multi-purpose Construction Crawler

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2008年第4期4卷 316-320页

作者：李文鸿孙劭文张琦孙伟史本广 college of Science Henan University of Technology Department of Equipment Unit 66336 of PLA engineering Institute of engineer corps PLA University of Science and Technology

An efficient multi-purpose construction crawler training simulator is developed based on windows platform using digital signal processing,multimedia,sensing,simulation modeling and real-time visualization simulation technologies. The simulator architecture and each part are discussed in this paper. The module designs for data acquisition,dynamic modeling and visual,sound and assess simulation are focused. The system has been put into practice and the satisfactory results are got.

关键词：计算机仿真模拟技术系统仿真