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A method based on potential theory for calculating air ca formation of an air cavity resistance reduction ship 被引量:8
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作者 李云波 吴晓宇 +1 位作者 马勇 王金光 《Journal of Marine Science and Application》 2008年第2期98-101,共4页
This research is intended to provide academic reference and design guidance for further studies to determine the most effective means to reduce a ship’s resistance through an air-cavity. On the basis of potential the... This research is intended to provide academic reference and design guidance for further studies to determine the most effective means to reduce a ship’s resistance through an air-cavity. On the basis of potential theory and on the assumption of an ideal and irrotational fluid, this paper drives a method for calculating air cavity formation using slender ship theory then points out the parameters directly related to the formation of air cavities and their interrelationships. Simulations showed that the formation of an air cavity is affected by cavitation number, velocity, groove geometry and groove size. When the ship’s velocity and groove structure are given, the cavitation number must be within range to form a steady air cavity. The interface between air and water forms a wave shape and could be adjusted by an air injection system. 展开更多
关键词 air cavity resistance reduction forming of air cavity potential theory cavitation number
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Histological changes following surgically-assisted rapid tooth movement through resistance reduction and distraction osteogenesis in dogs
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作者 Xi Chen1,Jian-Lin Liu2,Juan Dai3,Shuang Wang4,Ya-Li Huang11. Department of Stomatology,the First Affiliated Hospital,Medical School of Xi’an Jiaotong University,Xi’an 710061 2. Department of Stomatology,No.2 Traditional Chinese Medical Hospital,Shenzhen 518034 +1 位作者 3. Department of Orthodontics,School of Stomatology,Fourth Military Medical University,Xi’an 710032 4. Department of Orthodontics,Stomatological Hospital of Xi’an Jiaotong University,Xi’an 710004,China. 《Journal of Pharmaceutical Analysis》 SCIE CAS 2010年第2期139-142,共4页
Objective To investigate the histological changes of rapid tooth movement in dogs treated by resistance reduction and distraction osteogenesis,aiming to establish an animal model and further to reveal the remodeling m... Objective To investigate the histological changes of rapid tooth movement in dogs treated by resistance reduction and distraction osteogenesis,aiming to establish an animal model and further to reveal the remodeling mechanism of rapid tooth movement. Methods A total of 8 local hybrid dogs were selected as subjects for this study. The second pre-molar was extracted on both sides. The experimental side underwent alvelor surgery for resistance reduction and a home-made tooth-borne intraoral distraction device was installed for rapid tooth movement,while for the other side (control side) only tooth-borne intraoral distraction device was used for rapid tooth movement. The longest active force-delivery span was 2 weeks,followed by 6-week retention. The distance between the moved tooth and anchor unit was recorded weekly,and radiography was performed for each side before and after distraction. The surrounding tissues including periodontal ligament and alveolar bone were sectioned for histological analysis. Results The average distance of tooth movement was 3.55mm on the experimental side and 1.11mm on the control side. The rate of tooth movement was notably higher (P<0.01) and no significant apical root resorption was detected by X-ray on the experimental side. The active alvelor bone remodeling was found on the tension and pressure sides. However,there was no significant difference between the experimental side and the control side after the retention period. Conclusion The rate of orthodontic tooth movement can be accelerated through resistance reduction and periodontal distraction without any unfavorable effects but at minimal anchorage loss. 展开更多
关键词 periodontal ligament distraction osteogenesis resistance reduction rapid tooth movement
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Lateral resistance reduction induced by light-controlled leak current in silicon-based Schottky junction
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作者 王拴虎 张勖 +3 位作者 邹吕宽 赵靓 王文鑫 孙继荣 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第10期448-452,共5页
Lateral resistance of silicon-based p-type and n-type Schottky junctions is investigated. After one electrode on a metallic film is irradiated, the differential lateral resistance of the system is dependent on the dir... Lateral resistance of silicon-based p-type and n-type Schottky junctions is investigated. After one electrode on a metallic film is irradiated, the differential lateral resistance of the system is dependent on the direction of the bias current:it keeps constant in one direction and decreases in the opposite direction. By systematically investigating the electrical potential changes in silicon and the junction, we propose a new mechanism based on light-controlled leak current. Our work provides an insight into the nature of this phenomenon and will facilitate the advanced design of switchable devices. 展开更多
关键词 resistance reduction Schottky junction photovoltaic effect
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Resistance reduction of patterned surface inspired by cuticle structure of Achalinus spinalis
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作者 Jiahui ZHAO Keju JI +6 位作者 Qin CHEN Muhammad Niaz KHAN Chongwen TU Ze MA Jianming WU Jian CHEN Zhendong DAI 《Friction》 SCIE EI CAS CSCD 2023年第7期1359-1370,共12页
The crawling process of snakes is known to have fascinating tribological phenomena,whereas investigations on their frictional properties depending on patterned cuticles are insufficient.In this study,we have designed ... The crawling process of snakes is known to have fascinating tribological phenomena,whereas investigations on their frictional properties depending on patterned cuticles are insufficient.In this study,we have designed and fabricated biomimetic microstructures inspired by the geometric microunits of Achalinus spinalis cuticle using polyurethane acrylate(PUA)material and performed its tribological analysis.The micro-morphology of this Achalinus-inspired textured polymer surface(AITPS)is characterized by the closely and evenly quasi-rectangular microgrooves,periodically arranged along certain orientations.We have compared the frictional performance of our fabricated AITPS with other competitive microstructure,using a smooth steel ball and commercial clay as an interacting surface.After performing massive friction tests with steel ball and clay,AITPS still maintains good resistance reduction performed compared to the patterned surface with straight microgrooves,which is most likely due to the reduction of actual contact areas at the frictional interface. 展开更多
关键词 BIOMIMETIC MICROSTRUCTURE FRICTION resistance reduction
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Resistance reduction by bionic coupling of the earthworm lubrication function 被引量:12
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作者 LI JianQiao KOU BingXue +2 位作者 LIU GuoMin FAN WenFeng LIU LinLin 《Science China(Technological Sciences)》 SCIE EI CAS 2010年第11期2989-2995,共7页
Based on the biological coupling theory, the resistance reduction characteristic of the surface morphology and surface wettability of the earthworm were studied in this paper. The parameters of surface dorsal pore and... Based on the biological coupling theory, the resistance reduction characteristic of the surface morphology and surface wettability of the earthworm were studied in this paper. The parameters of surface dorsal pore and corrugation were extracted. According to these parameters, the lubrication mechanism of the earthworm surface was analyzed. The distribution of the pores and surface morphology were designed and the bionic coupling samples were prepared. The positive pressure, lubricant flow rate and advancing velocity were selected as the experiment factors while the soil friction resistance as observed object. According to the obtained data of bionic coupling samples from the testing system of biologic signal for tiny soil adhesion test, the optimal samples from the bionic coupling resistance reduction tests were selected through the range analysis. Compared to the normal ones, the soil resistance of bionic coupling samples was reduced by 76.8%. This is of great significance and offers bright prospects for reducing energy loss in terrain mechanics. 展开更多
关键词 bionic coupling EARTHWORM biological surface structure soil resistance reduction
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Research progress in the SO2 resistance of the catalysts for selective catalytic reduction of NOx 被引量:9
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作者 Minhua Zhang Baojuan Huang +1 位作者 Haoxi Jiang Yifei Chen 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第12期1695-1705,共11页
The selective catalytic reduction (SCR) of NOx with NH3 has been proven to be an efficient technology for NOx conversion to N2. However, the catalysts used for SCR usually suffer from the problem of sulfur poisoning... The selective catalytic reduction (SCR) of NOx with NH3 has been proven to be an efficient technology for NOx conversion to N2. However, the catalysts used for SCR usually suffer from the problem of sulfur poisoning which seriously limits their practical application. This review summarized sulfur poisoning mechanisms of various SCR deNG catalysts and strategies to reduce deactivation caused by SO2 such as doping metals, controlling the structures and morphologies of the catalysts, and selecting appropriate supports. The methods and procedures of catalysts preparation and the reaction conditions also have effect on SO2-resistance of the catalysts. Several novel catalyst systems that exhibited good SO2 resistance are also introduced. This paper could provide guidance for the development of highly efficient sulfur-tolerant deNOx catalysts. 展开更多
关键词 Words Selective catalytic reduction (SCR)SO2 resistance catalyst NOx
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Bionic Design and Finite Element Analysis of Elbow in Ice Transportation Cooling System 被引量:4
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作者 Dejun Miao~(1,2), Xiuhua Sui~3, Linjing Xiao~3 1. Key Laboratory of Mine Hazard Prevention and Control (Ministry of Education, China), Shandong University of Science and Technology, Qingdao 266510, P. R. China 2. School of Architecture, Tsinghua University, Beijing 100084, P. R. China 3. College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao 266510, P. R. China 《Journal of Bionic Engineering》 SCIE EI CSCD 2010年第3期301-306,共6页
With the increase in mining depth, mine heat harm has appeared to be more prominent. The mine heat harm could be resolvedor reduced by ice refrigeration. Thus, ice transportation through pipeline becomes a critical pr... With the increase in mining depth, mine heat harm has appeared to be more prominent. The mine heat harm could be resolvedor reduced by ice refrigeration. Thus, ice transportation through pipeline becomes a critical problem; typically flowresistance occurs in the elbow. In the present study, according to the analysis of the surface morphology of fish scale, abiomimetic functional surface structure for the interior wall of elbow is designed. Based on the theory of liquid-solid two phaseflow, a CFD numerical simulation of ice-water mixture flowing through the elbow is carried out using finite element method.Conventional experiments of pressure drop and flow resistance for both bionic and common elbows are conducted to test theeffect of the bionic elbow on flow resistance reduction. It is found that with the increase in the ice mass fraction in the ice-watermixture, the effect of bionic elbow on resistance reduction becomes more obvious. 展开更多
关键词 bionic elbow two phase flow ice transportation flow resistance reduction pressure loss
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Computation of brush short-circuit coefficients of DC machines for extremely low speed drives 被引量:1
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作者 张琪 谢国栋 黄苏融 《Journal of Shanghai University(English Edition)》 CAS 2006年第5期436-442,共7页
Short circuit due to the brushes over the commutator segments of DC machines causes reduction in the armature resistance and flux linkage, which is especially meaningful when the electric machine is running at zero or... Short circuit due to the brushes over the commutator segments of DC machines causes reduction in the armature resistance and flux linkage, which is especially meaningful when the electric machine is running at zero or extremely low speed. In design computation of DC machines, usually the average values of the coefficients are used in consideration of the effects of the short circuit. How-ever, the average values have complicated relationships with the parameters of electric machines, therefore, no usable mathematical model has been established yet for precise computation. In this paper, a relatively simple and generalized method for precise computation of the average values of the short-circuit coefficients is proposed. This method decouples some of the machine parameters and, therefore establishes a highly parameterized mathematical model and is convenient in formulation for computation. In addition, the computation data for one and two brush pairs, which are the most common cases, is provided. 展开更多
关键词 DC machine armature resistance flux linkage reduction of resistance and linkage.
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Algorithm of brush short-circuit coeffcients of DC machines for extremely low speed drives
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作者 张琪 谢国栋 黄苏融 《Journal of Shanghai University(English Edition)》 CAS 2008年第6期537-541,共5页
When a direct-current (DC) machine runs at extremely low speed or standstill, the reduction in the armature resistance and the armature flux linkage due to the short circuited coils by the brushes on the commutator ... When a direct-current (DC) machine runs at extremely low speed or standstill, the reduction in the armature resistance and the armature flux linkage due to the short circuited coils by the brushes on the commutator should not be neglected. Taking this reduction effect into account, the average values of the reduction coefficients relate to the machine parameters in complicated forms. In this paper, an effective algorithm for the precise computation of the average values of these reduction coefficients is proposed. Furthermore, in the algorithm, the effect of the insulation thickness between the commutator segments and the multiplicity of the wave winding are considered for the first time. The proposed algorithm can also be accommodated into the computer-aided design (CAD) of a DC machine, which normally runs at extremely low speed or standstill. 展开更多
关键词 direct-current (DC) machine armature resistance flux linkage reduction of resistance and linkage computeraided design (CAD) algorithm
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Numerical investigation of frictional drag reduction with an air layer concept on the hull of a ship 被引量:4
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作者 Jun Zhang Shuo Yang Jing Liu 《Journal of Hydrodynamics》 SCIE EI CSCD 2020年第3期591-604,共14页
A novel air bubble lubrication method using the winged air induction pipe (WAIP) device is used to reduce the frictional drag of the hull of the ship and hence increase the efficiency of the propulsion system. This bu... A novel air bubble lubrication method using the winged air induction pipe (WAIP) device is used to reduce the frictional drag of the hull of the ship and hence increase the efficiency of the propulsion system. This bubble lubrication technique utilizes the negative pressure region above the upper surface of the hydrofoil as the ship moves forward to drive air to the skin of the hull. In the present study, the reduction rate of the drag by applying the WAIP device is numerically investigated with the open source toolbox OpenFOAM. The generated air layer and the bubbles are observed. The numerical results indicate that the reduction rate of the drag closely depends on the depth of the submergence of the hydrofoil, the angle of attack of the hydrofoil, and the pressure in the air inlet. It is also proportional to the air flow rate. The underlying physics of the fluid dynamics is explored. 展开更多
关键词 Winged air induction pipe(WAIP) drag reduction frictional resistance reduction hull of ship OPENFOAM
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Long rectangular box jacking project:A case 被引量:7
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作者 Xiaolong Chen Baosong Ma +1 位作者 Mohammad Najafi Peng Zhang 《Underground Space》 SCIE EI 2021年第2期101-125,共25页
Rectangular pipe jacking or box jacking has become more popular in municipal applications because of its better adaptability to shallow overburdens and its higher structural section utilization than the conventional c... Rectangular pipe jacking or box jacking has become more popular in municipal applications because of its better adaptability to shallow overburdens and its higher structural section utilization than the conventional circular pipe jacking.This case study presents a utility tunnel constructed by using rectangular box jacking in Suzhou,China.The utility tunnel,which has a cross section of 9.1 m in width and 5.5 m in height,was jacked 233.6 m,which is the longest known single jacking length of a rectangular box jacking project in China.The box jacking mainly passed through a silty sand layer with high groundwater levels with a minimum depth of cover of only 3.5 m underneath the Yuanhetang River.In this zone,the structures on the surface are sensitive to external disturbance,thus increasing the challenges of construction.A series of measures were taken during the jacking process,and the project was successfully completed.This paper provides an overview of this project and introduces key techniques in the construction of working shafts as well as in the installation and retrieval of the box jacking machine.In addition,the use of lubrication to reduce friction resistance,navigation and application of an anti-buoyancy slab under the Yuanhetang River,and analyses of soil deformation caused by box jacking are described. 展开更多
关键词 Utility tunnel Rectangular box jacking Lubrication and friction resistance reduction technology Anti-buoyancy slab Ground deformation
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