检索结果-南通市图书馆

Wake structure and similar behavior of wake profiles downstream of a plunging airfoil

Chinese Journal of Aeronautics 2017年第4期30卷 1281-1293页

作者： ali R.DAVARI Department of Mechanical and Aerospace Engineering Science and Research Branch Islamic Azad University Tehran147789-3855 Iran

Very limited attention has already been paid to the velocity behavior in the wake region in unsteady aerodynamic problems. A series of tests has been performed on a flapping airfoil in a subsonic wind tunnel to study the wake structure for different sets of mean angle of attack, plunging amplitude and reduced frequency. In this study, the velocity profiles in the wake for various oscillation parameters have been measured using a wide shoulder rake, especially designed for the present experiments. The airfoil under consideration was a critical section of a 660 k W wind *** results show that for a flapping airfoil the wake structure can be of drag producing type, thrust producing or neutral, depending on the mean angle of attack, oscillation amplitude and reduced frequency. In a thrust producing wake, a high-momentum high-velocity jet flow is formed in the core region of the wake instead of the conventional low-momentum flow. As a result, the drag force normally experienced by the body due to the momentum deficit would be replaced by a thrust *** to the results, the momentum loss in the wake decreases as the reduced frequency increases. The thrust producing wake pattern for the flapping airfoil has been observed for sufficiently low angles of attack in the absence of the viscous effects. This phenomenon has also been observed for either high oscillation amplitudes or high reduced frequencies. According to the results, for different reduced frequencies and plunging amplitudes, such that the product of them be a constant, the velocity profiles exhibit similar behavior and coalesce on each other. This similarity parameter works excellently at small angles of attack. However, at near stall boundaries, the similarity is not as evident as before.

关键词： Hysteresis Plunging Reduced frequency Von Krmn street Wake

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Experimental Study on Heat Storage Properties Comparison of Paraffin/Metal Foams Phase Change Material Composites

引用

Journal of Thermal Science 2024年第2期33卷 469-478页

作者： Waqar AHMED Abid HUSSAIN Hanzla SHAHID Imran ali Hafiz Muhammad ali Department of Mechanical Engineering University of Engineering and TechnologyTaxila47080Pakistan Department of Mechanical Engineering Institute of Space TechnologyIslamabadPakistan Department of Mechanical Mechatronics and Manufacturing EngineeringUniversity of Engineering and Technology LahoreFaisalabad CampusPunjabPakistan Mechanical Engineering Department King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia Interdisciplinary Research Center for Renewable Energy and Power Systems(IRC-REPS) King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia

Heat storage properties of phase change materials(PCMs) are essential characteristics that perform a key role in thermal heat energy storage *** thermal properties of PCMs can be improved by developing metal foam/PCM *** addition of metal foam in PCMs has a significant effect on the thermal characteristics of *** this paper,the heat storage properties of two different metal foam/PCM composites were experimentally *** behavior of paraffin in metal foam(copper and iron-nickel)/paraffin composites concerning pure paraffin at a constant heat flux of 1000 W/m^(2) in three directions simultaneously(x,y,and z) was *** was infiltrated into copper and iron-nickel foams to develop composite materials which resulted in enhancing the thermal conductivity of the paraffin.A comparative analysis is made on the heat storage properties of paraffin in copper and iron-nickel foams/paraffin *** temperature distribution during the phase transition process is experimentally *** comparison indicates that temperature uniformity in copper foam/paraffin composite is better than in iron-nickel foam/paraffin composite and pure paraffin at the same heat *** results show that at heat flux of 1000 W/m^(2),the heat storage time for copper foam/paraffin composite is 20.63% of that of iron-nickel foam/paraffin composite.

关键词： heat storage capacity paraffin/metal foam composite temperature uniformity heat storage rate phase transition process

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Spin-3/2 Ising model AFM/AFM two-layer lattice with crystal field

引用

Chinese Physics B 2009年第10期18卷 4193-4207页

作者： Erhan Albayrak ali Yigit Department of Physics Erciyes University

The spin-3/2 Ising model is investigated for the case of antiferromagnetic （AFM/AFM） interactions on the two- layer Bethe lattice by using the exact recursion relations in the pairwise approach for given coordination numbers q=3, 4 and 6 when the layers are under the influences of equal external magnetic and equal crystal fields. The ground state （GS） phase diagrams are obtained on the different planes in detail and then the temperature-dependent phase diagrams of the system are calculated accordingly. It is observed that the system presents both second- and first-order phase transitions for all q, therefore, tricritical points. It is also found that the system exhibits double-critical end points and isolated points. The model also presents two Neel temperatures, TN, and the existence of which leads to the reentrant behaviour.

关键词： Bethe lattice spin ground state AFM/AFM layer phase

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Determination of critical parameters in the analysis of road tunnel fires

引用

International Journal of Mining Science and Technology 2019年第2期29卷 187-198页

作者： ali Haghighat Kray Luxbacher Department of Mining & Minerals Engineering Virginia Tech Fire Life Safety Tunnel Ventilation GroupAECOM

The analysis of the fluid characteristics downstream of a fire source in transportation tunnels is one the most important factor in the emergency response, evacuation, and the rescue service studies. Some crucial parameters can affect the fluid characteristics downstream of the fire. This research develops a statistical analysis on the computational fluid dynamics(CFD) data of the road tunnel fire simulations in order to quantify the significance of tunnel dimensions, inlet air velocity, heat release rate, and the physical fire size(fire perimeter) on the fluid characteristics downstream of the fire source. The selected characteristics of the fluid(response variables) were the average temperature, the average density, the average viscosity, and the average velocity. The prediction of the designed statistical models was assessed; then the significant parameters' effects and the parameters interactive effects on different response variables were determined individually. Next, the effect of computational domain length on the selection of the significant parameters downstream of the fire source was analyzed. In this statistical analysis, the linear models were found to provide the statistically good prediction. The effect of the fire perimeter and the parameters interactive effects on the selected response variables downstream of the fire, were found to be insignificant.

关键词： Road tunnel fire Two-level fractional factorial design Statistical two-level design CFD Fire dynamics

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Impulse force reductions and their effects on WBV exposures in high impact shovel loading operations

引用

International Journal of Mining Science and Technology 2018年第3期28卷 423-435页

作者： Danish ali Samuel Frimpong Mining & Nuclear Engineering Department Missouri University of Science and Technology

When shovels load the dump trucks with over 100-ton passes under gravity dumping conditions, they will create a large impact force on the dump truck body which generates high frequency shock waves which expose the operators to whole body vibrations （WBV）. The main cause of such truck vibrations is the large impact force due to the gravity dumping of large tonnage passes. Therefore a rigorous mathematical model has been developed for the impact force containing all the necessary factors upon which it depends. Latter, a thorough analysis shows that percentage reduction of 7.19%, 9.40%, 13.27%, 14.8%, 17.30% and 18.13% can he achieved by reducing the dumping distance to 6.33 m, 6.0 m, 5.5 m, 5.33 m, 5.0 m and 4.9 m, respectively, as compared to when the dumping distance was 7.33 m. Even more reduction in the magnitude of impact force can he observed if the shovel pass gets divided into more than two sub-passes. Therefore, these models can he used to figure out the number of sub-passes into which a single ore pass can he divided and/or the extent to which the dumping distance can he reduced which would reduce the impact force significantly enough to obtain safer yet economic operations.

关键词： Impact force HISLO Mathematical modeling Dumping distance Shovel ore sub-passes

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Multi-Objective Multi-Period Model for Humanitarian Relief Logistics with Split Delivery and Multiple Uses of Vehicles

引用

Journal of Systems Science and Systems Engineering 2020年第3期29卷 360-378页

作者： Maliheh Khorsi Seyed Kamal Chaharsooghi ali Bozorgi-Amiri ali Husseinzadeh Kashan Industrial Engineering Faculty of Industrial&Systems EngineeringTarbiat Modares UniversityTehranIran School of Industrial Engineering College of EngineeringUniversity of TehranTehranIran

Disaster relief logistics is a significant element in the management of disaster relief *** this paper,the operational decisions of relief logistics are considered in the distribution of resources to the affected areas to include scheduling,routing,and allocation *** proposed mathematical model simultaneously captures many aspects relevant to real life to face the challenging situation of *** such as multiple uses of vehicles and split delivery allow for better use of vehicles as one of the primary resources of disaster response.A multi-period multi-criteria mixed-integer programming model is introduced to evaluate and address these *** model utilizes a rolling horizon method that provides possibilities to adjust plans as more information becomes *** objectives of efficiency,effectiveness,and equity are jointly *** augmented epsilon constraint method is applied to solve the model,and a case study is presented to illustrate the potential applicability of our *** results show that the model is capable of generating efficient solutions.

关键词： Disaster management relief logistics vehicle routing problem multi-trip rolling horizon

来源：

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

Phase diagrams of the spin-2 Ising model in the presence of a quenched diluted crystal field distribution

引用

Chinese Physics B 2012年第11期21卷 114-120页

作者： ali Yigit Erhan Albayrak ankiri Karatekin University Department of Physics Erciyes University Department of Physics

We have investigated the random crystal field effects on the phase diagrams of the spin-2 Blume-Capel model for a honeycomb lattice using the effective-field theory with correlations. To do so, the thermal variations of magnetization are studied via calculating the phase diagrams of the model. We have found that the model displays both second-order and first-order phase transitions in addition to the tricritical and isolated points. Reentrant behavior is also observed for some appropriate values of certain system parameters. Besides the usual ground-state phases of the spin-2 model including ±2, ~1, and 0, we have also observed the phases ±3/2 and ±1/2, which are unusual for the spin-2 case.

关键词： spin-2 model random crystal field effective-field theory isolated critical points andtriciritical points

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Closed-loop bulk air conditioning: A renewable energy-based system for deep mines in arctic regions

引用

International Journal of Mining Science and Technology 2020年第4期30卷 511-516页

作者： ali Fahrettin Kuyuk Seyed ali Ghoreishi-Madiseh Faramarz P.Hassani NBK Institute of Mining Engineering University of British ColumbiaVancouverBritish Columbia V6T 1Z4Canada Department of Mining and Materials Engineering McGill UniversityMontrealQuebec H3A 0E8Canada

With depletion of shallow deposits,the number of underground mines expected to reach more than 3 km depth during their lifetime is *** surface cooling plants are mostly effective in mine airconditioning,usually secondary cooling units are needed below 2 *** need emerges due to the elevated thermal impacts caused by auto-compression of mine air as well as heat emissions from strata and mine *** a result,in cold climates,like Canada,ultra-deep mines need their secondary underground cooling plants running year-round while the intake air must be heated to protect the sensitive machinery and liners from freezing during the winter *** cool mine air,horizontal bulk-airconditioners with direct spray cooling systems are commonly used due to their high ***,sprayed water in bulk-air-coolers are mechanically circulated and refrigerated in coupled refrigeration *** set up can be transformed to a natural cooling/heating process by resurfacing the warm underground bulk-air-cooler spray water for mine air heating on the surface and re-sinking the chilled water for cooling in the underground bulk air *** could significantly cut-down the fossil-fuel consumption in burners for mine air pre-conditioning and refrigeration cost when *** paper presents an anonymous real-life example to study the feasibility of the proposed idea for an ultra-deep Canadian mine.

关键词： Energy recovery Renewable energy Mine energy systems Underground cooling Mine air preconditioning Ventilation HVAC Mine air heating

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Modeling and control for cooperative transport of a slung fluid container using quadrotors

引用

Chinese Journal of Aeronautics 2018年第2期31卷 262-272页

作者： Hassan SAYYAADI ali SOLTANI School of Mechanical Engineering Sharif University of Technology

In this paper, dynamic modeling and control problem for transfer of a sloshing liquid container suspended through rigid massless links from a team of quadrotors are investigated. By the proposed solution, pose of the slung container and fluid sloshing modes are stabilized appropriately. Dynamics of the container-liquid-quadrotors system is modeled by Euler-Lagrange *** slosh dynamics is included using multi-mass-spring model. According to derived model, a proper control law is designed for a system with three or more quadrotors. Implementing the proposed control law, quadrotors can control pose of the container, directions of the links and liquid sloshing modes simultaneously. Stability of closed loop system of tracking errors and sloshing modes are demonstrated using a theory of singularly perturbed systems and Lyapunov stability theorem. Also, the capability of the proposed feedback control laws in solving a formerly organized transport problem of a liquid filled container has been demonstrated in simulations. Moreover, priority of the proposed control scheme to an existing slung load controller in the literature is demonstrated.

关键词： Cooperative transport Dynamic modeling Liquid sloshing Lyapunov stability Pose control Quadrotors Slung load

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Anisian(Middle Triassic)Conodonts of the Kocaeli Triassic,Western Turkey

引用

Journal of Earth Science 2021年第3期32卷 616-632页

作者： ali Murat Kilic Department of Geological Engineering Faculty of EngineeringBalikesir UniversityBalikesirTurkey

The present study of Anisian(Middle Triassic)conodonts from the Kocaeli Peninsula(western Turkey)encompasses over 10 species of the families Gondolellidae and Gladigondolellidae,providing Early and Middle Triassic time constraints,Chiosella timorensis(Nogami,1968);Cornudina oezdemirae Gedik,1975;Gladigondolella tethydis(Huckriede,1958);Neostrachanognathus tahoensis Koike,1998;Paragondolella aegaea(Bender,1970);Paragondolella bulgarica Budurov and Stefanov,1975;Nicoraella kockeli(Tatge,1956);***(Sudar and Budurov,1979),and Gladigondolella *** established are Paragondolella hirschii *** and Budurov;*** *** ,Budurov,Petrunova and Mirauta;and *** ***.K?l??.The Kocaeli Anisian conodonts show a faunal affinity with *** present Anisian fauna is characteristic of the *** strong homeomorphy that characterizes the Anisian in western North America is discussed.

关键词： Triassic Anisian Aegean Bithynian conodonta Gebze(Kocaeli)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：