检索结果-南通市图书馆

Numerical Simulation of Tip Clearance Flow Passive Control in Axial Turbine

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

Journal of Thermal Science 2008年第2期17卷 147-155页

作者： LI wei QIAO wei-yang xu Kai-fu LUO Hua-ling College of Propulsion and EnergyNorthwestern Polytechnical University Xi＇an 710072 China

This paper focuses on the effects of five different passive turbine tip clearance flow control methods on the tip clearance flow physics, which consists of a partial suction side squealer tip, a double squealer tip, a pressure side tip shelf with inclined squealer tip on a double squealer tip, a tip platform extension edge in pressure side and in suction side respectively. A pressure-correction based, 3D Reynolds-averaged Navier-Stokes equations CFD code with Reynolds Stress Model was adopted. The variable specific heat was considered. The detailed tip clearance flow field with different squealer rims was described with the streamline and the velocity vector. Accordingly, the mechanisms of five passive controls were elucidated; the effects of the passive controls on turbine efficiency and tip clearance flow field were illuminated. The results showed that the secondary flow loss near the outer casing including the tip leakage losses and the passage vortex losses could be reduced in all the five passive control methods. The turbine efficiency could be increased via the rational passive turbine tip clearance flow control. The Improved PS Squealer had the best effect on turbine efficiency, and the efficiency increased by 0.215%.

关键词： contact face wave receiving tube absorber

Mechanical Assembly Packing Problem Using Joint Constraints

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2017年第6期32卷 1162-1171页

作者： Ming-Liang xu Ning-Bo Gu wei-wei xu Ming-Yuan Li Jun-Xiao xue Bing Zhou School of Information Engineering Zhengzhou University Zhengzhou 450000 China State Key Laboratory of Computer Aided Design and Computer Graphics Zhejiang University Hangzhou 310058 China School of Software Zhengzhou University Zhengzhou 450000 China

The three-dimensional packing problem is generally on how to pack a set of models into a given bounding box using the smallest packaging volume. It is known as an NP-hard problem. When discussing the packing problem in mechanical field, the space utilization of a mechanism is low due to the constraint of mechanical joints between different mechanical parts. Although such a situation can be improved by breaking the mechanism into components at every joint, it burdens the user when reassembling the mechanism and may also reduce the service life of mechanical parts. In this paper, we propose a novel mechanism packing algorithm that deliberately considers the DOFs （degrees of freedom） of mechanical joints. With this algorithm, we construct the solution space according to each joint. While building the search tree of the splitting scheme, we do not break the joint, but move the joint. Therefore, the algorithm proposed in this paper just requires the minimal number of splits to meet the goal of space utilization. Numerical examples show that the proposed method is convenient and efficient to pack three-dimensional models into a given bounding box with high space utilization.

关键词： NP-hard problem packing problem search tree

New Technique:Sketch-based rotation editing

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

Journal of Zhejiang University-Science C(Computers and Electronics) 2011年第11期12卷 867-872页

作者： Yue XIE wei-wei xu Yi-zhou YU Yan-lin WENG School of Computer Science and Technology Zhejiang University Hangzhou 310027 China Internet Graphics Group Microsoft Research Asia Beijing 100190 China Department of Computer Science University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA

We present a sketch-based rotation editing mations. Given a set of keyframe orientations of a rigid system for enriching rotational motion in keyframe ani- object, the user first edits its angular velocity trajectory by sketching curves, and then the system computes the altered rotational motion by solving a variational curve fitting problem. The solved rotational motion not only satisfies the orientation constraints at the keyframes, but also fits well the user-specified angular velocity trajectory. Our system is simple and easy to use. We demonstrate its usefulness by adding interesting and realistic rotational details to several keyframe animations.

关键词： Quaternions Keyframe interpolation Animation editing

Influence of filler characteristics on particle removal in fluid catalytic cracking slurry under an alternating electric field

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 2102-2111页

作者： Qiang Li Hui-Zhen Yang Can Yang Qing-Zhu Qiu wei-wei xu Zhao-Zeng Liu College of New Energy China University of Petroleum(East China)Qingdao266580ShandongChina

The characteristics of the packing material under an alternating electric field are an important factor in the removal of FCCS *** this study,the electric field distribution of a separation unit consisting of packed spheres under an alternating electric field is simulated,and the movement mechanism of catalyst particles is ***"effective contact point"model is derived to predict the adsorption of filler contact points on catalyst particles under the alternating electric field,and the model is validated by simulations and *** numerical calculation and experimental results indicate that the electrical properties of the filler spheres,the filler angleθ,and the frequency f of the alternating electric field affect the adsorption of catalyst *** the frequency of the electric field increases,the particle removal efficiency of the high-conductivity filler(silicon carbide)increases and then settles,and the separation efficiency of the low-conductivity filler(glass,zirconia)is not sensitive to the change in electric field frequency.

关键词： Fluid catalyticcracking slurry(FCCS) Particle AC electric field Fillers Removal

Effects of the properties of FCCS on the removing of catalyst particles from FCCS under a DC electrostatic field

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2023年第3期20卷 1885-1894页

作者： Qiang Li Qing-Zhu Qiu Hao Cao Hui-Zhen Yang wei-wei xu Zhao-Zeng Liu College of New Energy China University of Petroleum(East China)QingdaoShandong 266580China

Catalytic cracking is the main method to lighten heavy crude oil,this process can produce high quality oil products such as gasoline and diesel,but also produces a large amount of fluid catalytic cracking slurry(FCCS).The catalyst particles in FCCS seriously restrict the secondary processing of FCCS and need to be removed,and the properties of Fccs is an important factor that affects the removal efficiency of the catalyst *** on the"effective contact point"model proposed by the research group,this study further proposed the"electrostatic separation efficiency calculation"*** this model,since Fccs has a uniform distribution of catalyst particles,the ratio of the number of catalyst particles can be expressed as the ratio of area to achieve the calculation of separation *** the catalyst removal efficiency under different viscosity was analyzed,thus verifying the feasibility of this *** effects of temperature and mass ratio of four components on the viscosity of FccS were investigated respectively,then the effects of temperature and four components'mass ratio on the electrostatic sep-aration can be directly converted into the effect of viscosity on the electrostatic separation *** the results show the electrostatic separation efficiency decreases with increasing viscosity,and the best separationtemperatureis120℃.

关键词： Fluid catalytic cracking slurry(FCCS) Separation efficiency Viscosity Temperature Four components'mass ratio

Cyclopexy versus vitrectomy combined with intraocular tamponade for treatment of cyclodialysis

在线全文

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2013年第2期6卷 187-192页

作者： wei-wei xu Yi-Fei Huang Li-Qiang Wang Mao-Nian Zhang Department of Ophthalmology Chinese People's Liberation Army (PLA) General Hospital

AIM:Tocomparetheeffectsandcomplicationsof direc cyclopexy (DC) versus vitrectomy, endophotocoagulation, and gas/silicone oil endotamponade (VEE) treatment in patients with cyclodialysis and persistent ***: This is a prospective, comparative, non-randomized clinical trial which includes 52 patients with cyclodialysis and persisting hypotony. Fifty-two patients suffering from cyclodialysis and persistent hypotony in one eye were divided into 2 groups (groups DC and VEE) and treated, respectively, with direct cyclopexy or vitrectomy, endophotocoagulation, and gas/silicone oil endotamponade. The patients were followed up for 12 months. Assessments included best corrected visual acuity (BCVA), intraocular pressure (IOP), anterior chamber depth (ACD), anterior chamber volume (ACV) and subjective rating of the pain caused by the ***: After a follow-up of 12 months, significan improvement was seen in postoperative mean BCVA, IOP, ACD and ACV in both treatment groups (which were not significantly different from each other). The success rates for the treatments were not significantly different (DC: 50.0% vs VEE: 62.5% , P =0.383). Postoperative morbidity of cataract and subjective pain rating were significantly higher in the VEE group vs the DC group (P =0.003 and P <0.001 respectively).CONCLUSION: DC and VEE were effective surgica procedures in treating patients with cyclodialysis and persistent hypotony. Patients had better tolerance to DC treatment and VEE was more likely lead to cataract complications. Taking into consideration the ease of the operation, success rate, and patient comfort, DC treatment seems preferable to VEE treatment in patients with simple cyclodialysis. While VEE has the advantage of treating patients with cyclodialysis combined with vitreous hemorrhage.

关键词： cyclodialysis ocular hypotony cyclopexy vitrectomy

Analysis on characteristics of 1-D apodized and chirped photonic crystals containing negative refractive materials

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

Optoelectronics Letters 2008年第6期4卷 440-442页

作者： TONG Kai CUI wei-wei xu Xiao-hui LI Zhi-quan College of Electric Engineering University of Yanshan Qinhuangdao 066004China

Using transfer matrix method,the optical transmission properties of 1-D photonic crystals composed partially of negative refraction media are analyzed. The transmission spectra of periodic photonic crystal,chirped photonic crystal and apodized photonic crystal are numerically simulated respectively. By contrast with optical transmission properties of ordinary photo-nic crystals made of positive refraction media,the transmission spectra of apodized photonic crystal become unregular,the Bragg flat-headed area recurs but the peak of transmission does not change significantly. Futhermore,the band gap range of chirped photonic crystal diminishes gradually.

关键词：连续变频信号光子晶体折射材料晶体特征

Isolation and Identification of Two New Polyhydroxylated Sterols from Soft Coral Sinularia sp.

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2011年第2期27卷 217-220页

作者： LIAO Xiao-jian TANG Li-dan LIANG Yuan-wei GENG Hua-wei xu Shi-hai Department of Chemistry Jinan University Guangzhou 510632 P. R. China

Two new polyhydroxysteroids, 12β,16β,20-trihydroxycholesta-1,4-dien-3-one 16-acetate（1） and 24- methyl-12β,16β,20-trihydroxycholesta-1,4-dien-3-one（2） were isolated from octocoral Sinularia sp. Their structures were elucidated primarily on the basis of 1D and 2D NMR and the mass spectroscopic studies. The cytotoxicity of these compounds against three tumor cell lines was also reported.

关键词： Sinularia sp. Polyhydroxysteroid Cytotoxic activity

Prevention of debris flow disasters on Chengdu-Kunming Railway

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2001年第3期13卷 333-336页

作者： WANG wei, xu wei\|lin, LIU Shan\|jun(State Key Hydraulics Lab. of High Speed Flow, Sichuan University, Chengdu 610065, China. 四川大学高速水力学国家重点实验室四川成都 610065

Chengdu-Kunming Railway is an important transport line on southwestern China. However, this railway's safety is often threatened by debris flows. How to effectively forecast and alarm the debris flow disasters and reduce the losses is the aim to study the prevention system in this paper. The factors to cause or influence debris flow are divided into four parts-the basin environmental factors, the basin meteoric factors, the prevention work's elements and the flood-relief work's elements, and the prevention system is made up of three models-a judgment model to assess the debris flow gully's seriousness, a forecast model to predict the debris flow's occurrence and an alarm model to evaluate the debris flow's disaster. Afterwards, a concise structure chart is worked out and verified by the field data from Chengdu-Kunming Railway. This prevention system will provide beneficial reference for the debris flow's monitoring network to be executed on Chengdu-Kunming Railway.

关键词： debris flow disaster prevention system Chengdu-Kunming Railway