检索结果-南通市图书馆

Modelling internal air systems ingas turbine engines

在线全文

学校读者我要写书评

暂无评论

航空动力学报 2007年第4期22卷 505-520页

作者： j Michael Owen Department of Mechanical Engineering University of Bath

Rotating-disc systems can be used to model,experimentally and computationally,the flow and heat transfer that occur inside the internal cooling-air systems of gas turbine *** rotating-disc systems have been used successfully to simplify and understand some of the complex flows that occur in internal-air systems,and designers have used this insight to improve the cooling effectiveness,thereby increasing the engine efficiency and reducing the *** this review paper,three important cases are considered:hot-gas ingress;the pre-swirl system;and buoyancy-induced ***,or ingestion,occurs when hot gas from the mainstream gas path is ingested into the wheel-space between the turbine disc and its adjacent *** seals are fitted at the periphery of the system,and sealing flow is used to reduce or prevent ***,too much sealing air reduces the engine efficiency,and too little can cause serious overheating,resulting in damage to the turbine rim and blade *** the flow is three-dimensional and unsteady,there are encouraging signs that simple ‘orifice models’ could be used to estimate the amount of ingress into the *** a pre-swirl system,the cooling air for the gas-turbine blades is swirled by stationary nozzles,and the air is delivered to the blades via receiver holes in the rotating turbine *** the air reduces its temperature relative to the rotating blades,and the designer needs to calculate the air temperature and pressure drop in the *** designer also needs to calculate the effect of this swirling flow on the heat transfer from the turbine disc to the air,as this has a significant effect on the temperature distribution and stresses in the *** experimental and computational studies have given a better understanding of the flow and heat transfer in these ***-induced flow occurs in the cavity between two co-rotating compressor discs when the temperature of the discs is higher than

关键词：燃气涡轮机车空气动力学数学模型旋转式圆盘系统

Measurements of D^0-~0 mixing and searches for CP violation:HFAG combination of all data

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2008年第6期32卷 477-482页

作者： A.j.Schwartz Physics Department University of CincinnatiCincinnatiOhio 45221USA

We present world average values for D^0-D^0 mixing parameters x and y, CP violation parameters ｜q/P｜ and Arg（q/p）, and strong phase differences δ and δKππ. These values are calculated by the Heavy Flavor Averaging Group （HFAG） by performing a global fit to relevant experimental measurements. The results for x and y differ significantly from zero and are inconsistent with no mixing at the level of 6.7a. The results for ｜q/P｜ and Arg（q/p） are consistent with no CP violation. The strong phase difference δ is less than 45° at 95% C.L.

关键词： mixing CP violation

Three dimensional simulations of penetrative convection in a porous medium with internal heat sources

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2014年第2期30卷 144-152页

作者： A.j.Harfash Department of Mathematical Sciences University of Durham Department of Mathematics College of SciencesUniversity of Basrah

The problem of penetrative convection in a fluid saturated porous medium heated internally is analysed. The linear instability theory and nonlinear energy theory are derived and then tested using three dimensions *** Rayleigh numbers are obtained numerically for the case of a uniform heat source in a layer with two fixed surfaces. The validity of both the linear instability and global nonlinear energy stability thresholds are tested using a three dimensional simulation. Our results show that the linear threshold accurately predicts the onset of instability in the basic steady state. However, the required time to arrive at the basic steady state increases significantly as the Rayleigh number tends to the linear threshold.

关键词： Penetrative convection Nonlinear stability Linear instability Subcritical instability Finite difference

Laser induced photo-detachment of O2 in DC discharge

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2018年第7期20卷 98-105页

作者： j r legorreta j l patiNo f b yousif Centro de Investigacion en Ciencias Universidad Autonoma del Estado de Morelos.Av.UniversidadNo.1001 Col.Chamilpa Cuemavaca MorelosMexico

Determination of the negative ion number density of O2 and O in a DC discharge of oxygen plasma was made employing Langmuir probe in conjunction with eclipse laser photo- detachment technique. The temporal evolution of the extra electrons resulting from the photo- detachment of O2- and O- were used to evaluate the negative ion number density. The ratio of O2 number density to O varied from 0.03 to 0.22. Number density of both O~ and O increased with increasing power and decreased as the pressure was increased. Electron number density was evaluated from the electron energy distribution function （EEDF） using the I-V recorded characteristic curves. Electron temperature between 2 and 2.7 eV were obtained. Influence of the 02（al△g） metastable state is discussed.

关键词： electronegative plasma electron temperature Langmuir probe negative ion number density

Storing Freshwater Versus Storing Electricity in Power Systems with High Freshwater Electric Demand

在线全文

学校读者我要写书评

暂无评论

journal of Modern Power Systems and Clean Energy 2024年第2期12卷 323-333页

作者： Mubarak j.Al-Mubarak Antonio j.Conejo Department of Electrical and Computer Engineering The Ohio State UniversityColumbusOHUSA Department of Electrical Engineering Kuwait UniversityP.O.Box 5969Safat 13060Kuwait Department of Integrated Systems Engineering and the Department of Electrical and Computer Engineering The Ohio State UniversityColumbusOH 43210USA IEEE

We consider a power system whose electric demand pertaining to freshwater production is high(high freshwater electric demand),as in the Middle East,and investigate the tradeoff of storing freshwater in tanks versus storing electricity in batteries at the day-ahead operation *** storing freshwater and storing electricity increase the actual electric demand at valley hours and decrease it at peak hours,which is generally beneficial in term of cost and ***,to what extent?We analyze this question considering three power systems with different generation-mix configurations,i.e.,a thermal-dominated mix,a renewable-dominated one,and a fully renewable *** generation-mix configurations are inspired by how power systems may evolve in different countries in the Middle *** production uncertainty is compactly modeled using chance *** draw conclusions on how both storage facilities(freshwater and electricity)complement each other to render an optimal operation of the power system.

关键词： Power system operation freshwater production and transportation coordination day-ahead scheduling

3D kinematicmandiblemodel to designmandibular advancement devices for the treatment of obstructive sleep apnea

在线全文

学校读者我要写书评

暂无评论

Bio-Design and Manufacturing 2021年第1期4卷 22-32页

作者： M.García j.A.Cabrera A.Bataller S.Postigo j.j.Castillo Department of Mechanical Engineering University of MálagaC/Doctor Ortiz Ramos s/nAmpliación Campus Teatinos29071 MálagaSpain

Mandibular advancement devices(MADs)are one of the treatments used for Obstructive sleep apnea(OSA).MADs try to maintain the mandible in an advanced position to keep the upper airways open when *** achieve this goal,most current MADs limit the mouth opening to a few *** study of the kinematic behaviour of the patient’s jaw is essential in order to design devices that allow greater aperture *** this purpose,a 3D multibody model that reproduces jaw movement has been developed in this *** this end,the movement of the lower incisor has been determined by means of a vision system and reflective *** addition,the kinematics of the temporomandibular joint has been ***,the device is designed and printed using a cam-follower *** way,the cam profiles and the followers are optimally designed and positioned for each patient depending on the physiognomy of the jaw and the opening and advancing movement prescribed by the specialist.

关键词： Mandibular advancement device 3D mandible kinematics Cam-follower mechanism 3D printed devices

One-step multi-compositional oxidation of YSi alloy:Experiments and ab initio computation

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2023年第27期158卷 253-262页

作者： W.j.Wang j.C.Luo L.Chen G.j.Yang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an jiaotong University Suzhou Institute Suzhou 215123China

YSi alloy is a promising candidate as oxidation resistant coatings for both the bond coat of environmental barrier coatings(EBCs)and anti-ablation coatings at a high temperature of∼1300℃.In this study,a one-step multi-compositional oxidation by rapid heating oxidation mode is proposed to reduce the oxidation rate by 3.6 times compared to conventional slow heating oxidation *** show that preferentially formed Y_(2)O_(3) oxide initiates a multi-step oxidation,produces a cracking and porous oxides,and thereby resulting in a fast oxidation with *** one-step multi-compositional oxidation with a compact and dense Y_(2)Si_(2)O_(7)scale contributes to the much better oxidation resistance for rapid heating oxidation mode of YSi *** stable formation of Y_(2)Si_(2)O_(7)scale is comprehensively understood by the energy barrier,charge density and electronic level based on density functional *** study demonstrates a promising application of YSi alloy by rapid heating oxidation mode.

关键词： YSi alloy One-step oxidation Multi-compositional scale Y_(2)Si_(2)O_(7) Energy barrier

Effect of Solute Contents of Al-Ni-Sr Alloy on Glass Forming Ability and Thermal Stability

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 Rare Earths 2004年第z2期22卷 73-77页

作者： Taek Soo Kim j K Lee H j Kim j C Bae Advanced Materials R&D Center Korea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea

Glass forming ability (GFA) and structural characterization of a new amorphous Al-Ni-Sr alloy melt spun were investigated on the theory of the factors for the glass formation. The GFA was varied with the ratio of Ni to Sr in detail and successful amorphous phase dispersed with 2 ～ 5 nm precipitates was prepared from Al-Ni5-Sr3. Thermal stability and crystallization behavior of the amorphous phase were determined by continuous and isothermal heating technique on DCS, resulting that the crystallization occurs by the growth of fcc Al nanocrystals on the preexistent nuclei.

关键词： glass formation crystallization Al base amorphous alloys rapid solidification

Mg-Al Alloys Manufactured by Casting and Hot Working Process

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 Materials Science & Technology 2008年第1期24卷 96-98页

作者： j.M.Kim j.H.jun W.j.jung Department of Applied Materials Eng. Hanbat National University Daejeon 305-719 Korea Light Materials Team Korea Institute of Industrial Technology Incheon 406-800 Korea

Mechanical properties of Mg-Al based alloys at different fabrication state,namely as-cast,hot rolled,and annealed,were investigated to develop the alloys that are suitable for the casting/hot working ***- imental results indicated that the castability such as hot cracking resistance tends to improve with increasing the aluminum ***,the elongation at elevated temperatures was observed to decrease as the AI content increases,implying difficulties in hot forming.A small amount of Zr additions could significantly enhance the room temperature mechanical properties of hot-rolled Mg-6%Al-1%Zn *** tendency of remarkable grain coarsening at high temperatures was effectively reduced by the Zr *** analyses suggested that very fine Al-3Zr precipitates formed in the Zr-added alloy are responsible for the obtained results.

关键词： Magnesium Casting Forming Tensile properties