检索结果-南通市图书馆

Numerical stabilities of loosely coupled methods for robust modeling of lightweight and flexible structures in incompressible and viscous flows

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第4期33卷 709-724页

作者： Deniz tolga Akcabay Jian Xiao Yin lu Young Department of Naval Architecture and Marine Engineering University of Michigan 2600 Draper Dr. Ann ArborMI 48109-2145 USA

The growing interest to examine the hydroelastic dynamics and stabilities of lightweight and flexible materials requires robust and accurate fluid–structure interaction（FSI）models. Classically, partitioned fluid and structure solvers are easier to implement compared to monolithic methods;however, partitioned FSI models are vulnerable to numerical（“virtual added mass”） instabilities for cases when the solid to fluid density ratio is low and if the flow is *** a partitioned method, the loosely hybrid coupled（LHC）method, which was introduced and validated in Young et al.（Acta Mech. Sin. 28：1030–1041, 2012）, has been successfully used to efficiently and stably model lightweight and flexible structures. The LHC method achieves its numerical stability by, in addition to the viscous fluid forces, embedding potential flow approximations of the fluid induced forces to transform the partitioned FSI model into a semi-implicit scheme. The objective of this work is to derive and validate the numerical stability boundary of the LHC. The results show that the stability boundary of the LHC is much wider than traditional loosely coupled methods for a variety of numerical integration schemes. The results also show that inclusion of an estimate of the fluid inertial forces is the most critical to ensure the numerical stability when solving for fluid–structure interaction problems involving cases with a solid to fluid-added mass ratio less than one.

关键词： incompressible viscous lightweight partitioned validated discretization solver embedding stably Reynolds

Synthesis and thermoluminescence properties of rare earth oxides (Y, Ce-lu) doped lithium triborate

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2011年第6期29卷 618-622页

作者： tolga Depci Gulhan Ozbayoglu Aysen Yilmaz Department of Mining Engineering Faculty of Engineering and Architecture Yuzuncu Yil University Faculty of Engineering Atilim University Department of Chemistry Middle East Technical University

Lithium triborate （LiB3O5） was synthesized by high temperature solid-state reaction method, and then rare earth oxides were doped into LiB3O5 to enhance its thermoluminescent （TL） properties. The identification and characteristics of the obtained compounds were determined by X-ray diffraction （XRD）, Fourier transform infrared （FTIR） analyses, differential thermal analyses （DTA） and scanning electron microscopy （SEM）. The glow curves were obtained using a thermoluminescent （TL） reader. The results revealed that all the rare earth oxides were not good activators for lithium triborate and the obtained compounds could not be used for dosimetric applications.

关键词： lithium triborate solid state thermoluminescent rare earth oxides

How to select the appropriate candidate of pulmonary arterial hypertension： specific therapy in elderly patients with pulmonary hypertension

在线全文

学校读者我要写书评

暂无评论

Journal of Geriatric Cardiology 2017年第1期14卷 17-19页

作者： Yalin tolga Yaylali Department of Cardiology Pamukkale University Denizli Turkey.

Recent reports from pulmonary arterial hypertension （PAH） registries suggest that the mean age at diagnosis is increasing in a growing proportion of elderly patients. The combination of several reasons such as aging popula- tion, increase in life expectancy, growing PAH awareness of physicians and patients, and availability of more treatment options could explain the changing picture of PAH. PAH should be considered as an emerging entity in the elderly.

关键词： Pulmonary hypertension Pulmonary vasodilator therapy The elderly

A review on the gun barrel vibrations and control for a main battle tank

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2017年第5期13卷 353-359页

作者： tolga Dursun Firat Biiyiikcivelek Cagrihan Utlu Aselsan Inc MGEO Division CankiriYolu 7.km AkyurtAnkara 06750Turkey

Achieving high hitting accuracy for a main battle tank is challenging while the tank is on the move. This can be reached by proper design of a weapon control and gun system. In order to design an effective gun system while the tank is moving, better understanding of the dynamic behavior of the gun system is required. In this study, the dynamic behaviour of a gun system is discussed in this respect. Both experimental and numerical applications for the determination of the dynamic behaviour of a tank gun system are investigated. Methods such as the use of muzzle reference system(MRS) and vibration absorbers, and active vibration control technology for the control and the reduction of the muzzle tip deflections are also reviewed. For the existing gun systems without making substantial modifications,MRS could be useful in controlling the deflections of gun barrels with estimation/prediction *** vibration levels could be cut into half by the use of optimised vibration absorbers for an existing gun.A new gun system with a longer barrel can be as accurate as the one with a short barrel with the appropriate structural modifications.

关键词： Gun dynamics Vibration control Muzzle reference system Vibration absorber

Effect of Wood-drying Condensate on Emission of Volatile Organic Compounds and Bonding Properties of Fibreboard

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2020年第1期17卷 206-214页

作者： Nadir Ayrilmis tolga kapti Ali Gürel Martin Ohlmeyer Department of Wood Mechanics and Technology Forest FacultyIstanbul University-CerrahpasaIstanbul 34473Turkey Polisan kimya San.A.(S). Dilovas(i)Organize Sanayi B(o)lgesi 1.K(i)s(i)m Liman Cad.No:7Dilovas(i)41455Turkey Forest Research Institute Marmara RegionGeneral Directorate of Forestry of TurkeyIstanbul 34398Turkey Thünen-Institut für Holzforschung Thünen Institute of Wood ResearchLeuschnerstr.91 cHamburg 21031Germany

Potential use of condensate generated by cooling the steam obtained during high-frequency/vacuum drying step of hardwood lumber was *** liquid condensates were obtained from oak,beech and walnut *** liquid condensate was then used as a replacement for deionized water in the synthesis of Urea-Formaldehyde(UF)resin(5 wt%of total resin)using a laboratory scale *** Density Fibreboards(MDFs)were produced using control and modified *** of Volatile Organic Compounds(VOCs)from the MDFs were determined by Micro Chamber *** bonding properties of the MDFs were determined according to European *** main VOC emissions from MDFs produced using UF resin containing the condensate were a-Pinene,b-Pinene,careen,and acetic acid,which were lower than those of the control MDF,except for the acetic acid emission of MDF with oak *** the tree species,the beech wood condensate gave the lowest VOC emissions(732μg·m^-3)from the MDFs,followed by the MDFs containing walnut wood condensate(852μg·m^-3),oak wood condensate(998μg·m^-3),and control MDF(3529μg·m^-3),***,the internal bond strength of MDFs containing the condensate was negatively impacted by the condensate(0.70 N·mm^-2 to 0.54 N·mm^-2 depending on the tree species).The results showed that the liquid wood-drying condensate which generally released to the ground could be efficiently used as an alternative to expensive VOCs scavenger used in the production of UF resin bonded *** may be one of the most efficient uses of the condensate in high value-added materials.

关键词： bionics condensate fibreboard urea-formaldehyde VOCs

CAPACITY ALLOCATION AND COORDINATION ISSUES FOR THE TIMELY PROCESSING OF OUTSOURCED OPERATIONS

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 Systems Science and Systems Engineering 2014年第3期23卷 300-312页

作者： tolga Aydinliyim Xiaoqiang Cai George L.Vairaktarakis Loomba Department of Management Zicklin School of Business Baruch CollegeCity University of New YorkNew YorkNY USA 10010-5585 Department of Systems Engineering and Engineering Management The Chinese University of Hong kong Department of Operations Weatherhead School of Management Case Western Reserve UniversityClevelandOH USA 44106-72350

We consider dynamic capacity booking problems faced by multiple manufacturers each outsourcing certain operations to a common third-party firm. Each manufacturer, upon observing the current state of the third-party schedule, books capacity with the objective to jointly minimize holding costs that result from early deliveries, tardiness penalties due to late deliveries, and third-party capacity booking costs. When making a reservation, each manufacturer evaluates two alternative courses of action：（i） reserving capacity not yet utilized by other manufactures who booked earlier; or （ii） forming a coalition with a subset or all of other manufacturers to achieve a schedule minimizing coalition costs, i.e., a centralized schedule for that coalition. The latter practice surely benefits the coalition as a whole; however, some manufacturers may incur higher costs if their operations are either pushed back too much, or delivered too early. For this reason, a cost allocation scheme making each manufacturer no worse than they would be when acting differently （i.e., participating in a smaller coalition or acting on their own behalf,） must accompany centralized scheduling for the coalition. We model this relationship among the manufacturers as a cooperative game with transferable utility, and present optimal and/or heuristic algorithms to attain individually and eoalitionally optimal schedules as well as a linear program formulation to find a core allocation of the manufacturers＇ costs.

关键词： Outsourcing scheduling capacity allocation cooperative games

Internet of Things Supported Airport Boarding System and Evaluation with Fuzzy

在线全文

学校读者我要写书评

暂无评论

Intelligent Automation & Soft Computing 2023年第3期35卷 2687-2702页

作者： tolga Memika Tulay korkusuz Polat Sakarya University Sakarya54054Turkey

The existing systems sustained with the investments made require more automation and digital transformation with the continuous advancement of *** aviation industry is a sector that is open to more automation and digi-tal transformation,mainly because of the intense competition and the analysis of a large variety of *** long duration of operations in current airline processes and some processﬂows cause customer dissatisfaction and cost *** this study,the boarding process,which is one of the operational processes of airline transportation and is open to improvement,was *** classical boarding process has been redesigned using Internet of Things technology a model called Boarding 4.0 was *** Boarding 4.0,it is aimed to design a process where passengers can take their time before boarding more efﬁ*** the study,the sub-processes of the Boarding 4.0 model,other processes that the sub-processes interact with,their activities,and data exchange passenger move-ments during the activities are explained in *** to the classical boarding process and Boarding 4.0 with the fuzzy ahp technique,it has been shown that boarding 4.0 is more advantageous and passenger movement times can be reduced during *** a result of the evaluation made with the fuzzy ahp,it was determined that boarding 4.0 is more advantageous than the classical boarding *** addition,when the total time of the sub-activities in the board-ing process is calculated,boarding activities for a passenger take 50 min with the classic boarding process and 20 min with Boarding ***,when Boarding 4.0 is used,the passenger gains 30 ***,when the calculation is made concerning the airport’s current capacity,two passengers are hosted with the clas-sical boarding process,whileﬁve passengers are hosted with Boarding *** acquisition is signiﬁcant for airports in terms of efﬁcient use of resources.

关键词： Intelligent airport internet of things boarding system process management model fuzzy ahp

ROBUST TRADING RULE SELECTION AND FORECASTING ACCURACY

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 Systems Science & Complexity 2014年第1期27卷 169-180页

作者： SCHMIDBAUER Harald ROSCH Angi SEZER tolga TUNALIOGlu Vehbi Sinan Department of Business Administration Istanbul Bilgi University Santral Campus 34060 Eyiip IstanbulTurkey. FOM University of Applied Scienees Study Centre Munich Arnulfstr. 30 80335 Miinchen Germany. DIME University of Genoa Via Opera Pia 15 16145 Genoa Italy.

Trading rules performing well on a given data set seldom lead to promising out-of-sample results, a problem which is a consequence of the in-sample data snooping bias. Efforts to justify the selection of trading rules by assessing the out-of-sample performance will not really remedy this predica- ment either, because they are prone to be trapped in what is known as the out-of-sample data-snooping bias. Our approach to curb the data-snooping bias consists of constructing a framework for trading rule selection using a-priori robustness strategies, where robustness is gauged on the basis of time- series bootstrap and multi-objective criteria. This approach focuses thus on building robustness into the process of trading rule selection at an early stage, rather than on an ex-post assessment of trading rule fitness. Intra-day FX market data constitute the empirical basis of the proposed investigations. Trading rules are selected from a wide universe created by evolutionary computation tools. The authors show evidence of the benefit of this approach in terms of indirect forecasting accuracy when investing in FX markets.

关键词： A-priori robustness data-snooping bias efficient market hypothesis evolutionary com-putation intra-day FX markets time-series bootstrap trading rule selection.

Hybrid algorithm for modeling of fluid-structure interaction in incompressible, viscous flows

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2012年第4期28卷 1030-1041页

作者： Eun Jung Chae Deniz tolga Akcabay Department of Naval Architecture and Marine Engineering University of Michigan

The objective of this paper is to present and to validate a new hybrid coupling （HC） algorithm for modeling of fluid-structure interaction （FSI） in incompressible, viscous flows. The HC algorithm is able to avoid numerical instability issues associated with artificial added mass effects, which are often encountered by standard loosely coupled （LC） and tightly coupled （TC） algorithms, when modeling the FSI response of flexible structures in incompressible flow. The artificial added mass effect is caused by the lag in exchange of interfacial displacements and forces between the fluid and solid solvers in partitioned algorithms. The artificial added mass effect is much more prominent for light/flexible struc- tures moving in water, because the fluid forces are in the same order of magnitude as the solid forces, and because the speed at which numerical errors propagate in an incom- pressible fluid. The new HC algorithm avoids numerical instability issues associated with artificial added mass effects by embedding Theodorsen＇s analytical approximation of the hydroelastic forces in the solution process to obtain better initial estimates of the displacements. Details of the new HC algorithm are presented. Numerical validation studies are shown for the forced pitching response of a steel and a plastic hydrofoil. The results show that the HC algorithm is able to converge faster, and is able to avoid numerical insta- bility issues, compared to standard LC and TC algorithms, when modeling the transient FSI response of a plastic hydrofoil. Although the HC algorithm is only demonstrated for a NACA0009 hydrofoil subject to pure pitching motion, the method can be easily extended to model general 3-D FSI response and stability of complex, flexible structures in turbulent, incompressible, multiphase flows.

关键词： Fluid-structure interaction Viscous Incom- pressible Computational Added Mass Stability