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Interaction between Struts and Swirl Flow in gas Turbine Exhaust Diffusers

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Journal of Thermal Science 2005年第4期14卷 314-320页

作者： roman Z.pIETrASCH Joerg r.SEUME Turbomachinery Laboratory University of Hannover Appelstr. 9 D-31678 Hannover Germany

The increasing use of gas turbines in combined cycle power plants together with the high amount of kinetic energy in modem gas turbine exhaust flows focuses attention on the design of gas turbine diffusers as the connecting part between the Brayton/Joule and the rankine parts of the combined cycle. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. The test rig consists of a radial type, variable swirl generator which provides the exhaust flow corresponding to different gas turbine operating conditions. Static pressure measurements are carried out along the outer diffuser walls and along the hub of the annular part and along the centerline of the conical diffuser. Velocity distributions at several axial positions in the annular and conical diffuser have been measured using a Laser Doppler Velocimeter （LDV）. pressure recovery coefficients and velocity profiles are depicted as a function of diffuser length for several combinations of swirl strength, tip flow and strut geometries. The diffuser without struts achieved a higher pressure recovery than the diffuser with struts at all swirl angle settings. The diffuser with cylindrical struts achieved a higher pressure recovery than the diffuser with profiled struts at all swirl angle ***. Inlet flows with swirl angles over 18° affected the pressure recovery negatively for all strut configurations.

关键词： gas turbine exhaust diffuser swirl struts pressure recovery coefficient.

On the Homology of the Dual de rham Complex

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Acta Mathematica Sinica,English Series 2022年第10期38卷 1666-1676页

作者： roman MIKHAILOV Laboratory of Modern Algebra and Applications St.Petersburg State University14th Line29bSaint Petersburg199178Russia St.petersburg Department of Steklou Mathematical Institute Fontanka 27SaintPetersburg191023Russia

We study the homology of the dual de rham complex as functors on the category of abelian *** give a description of homology of the dual de rham complex up to degree 7 for free abelian groups and present a corrected ve... 详细信息

关键词： Dual de rham complex polynomial functor divided powers derived functors

What can a heavy U(1)B-L Z'boson do to the muon(g-2)u anomaly and to a new Higgs boson mass?

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Chinese physics C 2021年第1期45卷 32-46页

作者： Antonio p.Morais roman pasechnik J.pedro rodrigues Departamenlo de Fisica da Universidade de Aveiro and CIDMA Campus de Santiago 3810-183 AveiroPortugal Department of Astronomy and Theoretical physics Lund UniversitySE 223-62 LundSweden Nuclear physics Institute ASCr 25068 RezCzech Republic Departamento de Fisica CFMUniversidade Federal de Santa CatarinaC.P.476CEP 88.040-900FlorianopolisSCBrazil

The minimal U(1)B_L extension of the Standard Model(B-L-SM)offers an explanation for neutrino mass generatio n via a seesaw mechanism;it also offers two new physics states,namely an extra Higgs bos on and a new Z'gauge *** emerge nee of a second Higgs particle as well as a new Z'gauge boson,both lin ked to the breaking of a local U(1)B_L symmetry,makes the B-L-SM rather constrained by direct searches in Large Hadron Collider(LHC)*** investigate the phenomenological status of the B-L-SM by confr on ting the new physics predictions with the LHC and electroweak precision *** into account the current bounds from direct LHC searches,we demonstrate that the prediction for the muon(g-2)u anomaly in the B-L-SM yields at most a contribution of approximately 8.9×10^-12,which represents a tension of 3.28 standard deviations,with the current 1σuncertainty,by means of a Z'boson if its mass is in the range of 6.3 to 6.5 TeV,within the reach of future LHC *** means that the B-L-SM,with heavy yet allowed Z‘bos on mass range,in practice,does not resolve the tension between the observed anomaly in the muon(g-2)u and the theoretical prediction in the Standard *** a heavy Z'boson also implies that the minimal value for the new Higgs mass is of the order of 400 geV.

关键词： beyond Standard Model Higgs physics gauge extensions of the Standard Model Z'boson

The root Cap Determines Ethylene-Dependent growth and Development in Maize roots

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Molecular plant 2008年第2期1卷 359-367页

作者： Achim Hahn roman Zimmermann Dierk Wanke Klaus Harter Hans g. Edelmann Botanisches Institut Universitfit zu Koin Gyrhofstr. 15 D-50931 Koin Germany present address: ZMBp pflanzenphysiologie University TQbingen Auf der Morgenstelle 1 D-72076 TQbingen Germany Institut fur Entwicklungsbiologie Universitat zu Koin Gyrhofstr. 17 D-50931 Koin Germany Institut fur Entwicklungsbiologie Universitat zu Koin Gyrhofstr. 17 D-50931 Koln Germany ZMBp pflanzenphysiologie Universitat Tubingen Auf der Morgenstelle 1 D-72076 Tubingen Germany present address: Biologie und ihre Didaktik Universitat Siegen D-57068 Siegen Germany

Besides providing protection against mechanical damage to the root tip, the root cap is involved in the perception and processing of diverse external and internal stimuli resulting in altered growth and development, The transduction of these stimuli includes hormonal signaling pathways such as those of auxin, ethylene and cytokinin. Here, we show that the root cap is essential for the ethylene-induced regulation of elongation growth and root hair formation in maize. Exogenously applied ethylene is no longer able to inhibit elongation growth when the root cap has been surgically removed prior to hormone treatment. reconstitution of the cap positively correlates with the developing capacity of the roots to respond to ethylene again. In contrast, the removal of the root cap does not per se affect growth inhibition controlled by auxin and cytokinin. Furthermore, our semi-quantitative rT-pCr results support earlier findings that the maize root cap is a site of high gene expression activity with respect to sensing and responding to hormones such as ethylene, From these data, we propose a novel function of the root cap which is the establishment of competence to respond to ethylene in the distal zones of the root.

关键词： rOOT hairs (Botany) ETHYLENE ALKENES pLANT hormones CONTACT inhibition (Biology)

Dynamic Modelling of the DEp Controlled Boiling in a Microchannel

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Journal of Thermal Science 2018年第2期27卷 167-174页

作者： Marcin Lackowski roman Kwidzinski Institute of Fluid Flow Machinery Polish Academy of Sciences

The paper presents theoretical analysis of flow dynamics in a heated microchannel in which flow rate may be controlled by dielectrophoretic(DEp) forces. proposed model equations were derived in terms of lumped parameters characterising the system comprising of DEp controller and the microchannel. In result, an equation for liquid height of rise in the controller was obtained from momentum balances in the two elements of the considered system. In the model, the boiling process in the heated section of microchannel is taken into account through a pressure drop, which is a function of flow rate and uniform heat flux. presented calculation results show that the DEp forces influence mainly the flow rate in the microchannel. In this way, by proper modulation of voltage applied to the DEp controller, it is possible to lower the frequency of Ledinegg instabilities.

关键词： dielectrophoresis boiling microchannel two-phase flow pressure drop

Modeling static friction behavior of elastic–plastic spherical adhesive microcontact in full-stick condition

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Friction 2024年第11期12卷 2594-2610页

作者： guo XIANg roman gOLTSBErg Izhak ETSION Department of Mechanical Engineering TechnionHaifa 32000Israel

The static friction behavior of an elastic–plastic spherical adhesive microcontact between a rigid flat and a deformable sphere under combined normal and tangential loading is studied by the finite element method(FEM).The contact between the sphere and the rigid flat is assumed to be full-stick,and the sliding inception is related to a loss of tangential *** intermolecular force between the rigid flat and the sphere is assessed by the Lennard–Jones(LJ)potential,which is applied to the sphere and the rigid flat by a user *** evolution of the adhesive force with tangential displacement in the full-stick condition is *** results indicate that the increasing effect of adhesive energy on the static friction coefficient gradually diminishes with an increase in the adhesive energy and the external normal ***,based on an extensive parametric study,an empirical dimensionless expression is obtained to predict the static friction coefficient of the spherical adhesive microcontact considering the intermolecular force.

关键词： adhesive spherical microcontact Lennard–Jones(LJ)potential elastic–plastic static friction

An in vitro demonstration of a passive,acoustic metamaterial as a temperature sensor with mK resolution for implantable applications

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Microsystems & Nanoengineering 2024年第1期10卷 41-54页

作者： Lucrezia Maini Vicente genovés roman Furrer Nikola Cesarovic Christofer Hierold Cosmin roman Micro-and Nanosystems Department of Mechanical and Process EngineeringETH ZurichTannenstrasse 38092 ZurichSwitzerland. Translational Cardiovascular Technology Department of Health Science and TechnologyETH ZurichLeopold-Ruzicka-Weg 48093 ZurichSwitzerland. Transport at Nanoscale Interfaces Swiss Federal Laboratories for Materials Science and TechnologyEMPAÜberlandstrasse 1298600 DübendorfSwitzerland Department of Cardiothoracic and Vascular Surgery Deutsches Herzzentrum der Charite(DHZC)13353 BerlinGermany

Wireless medical sensors typically utilize electromagnetic coupling or ultrasound for energy transfer and sensor *** transfer and management is a complex aspect that often limits the applicability of implantable sensor *** this work,we report a new passive temperature sensing scheme based on an acoustic metamaterial made of silicon embedded in a polydimethylsiloxane *** to other approaches,this concept is implemented without additional electrical components in situ or the need for a customized receiving unit.A standard ultrasonic transducer is used for this demonstration to directly excite and collect the reflected *** metamaterial resonates at a frequency close to a typical medical value(5 MHz)and exhibits a high-quality *** the design features of the metamaterial with the high-temperature sensitivity of the polydimethylsiloxane matrix,we achieve a temperature resolution of 30 *** value is below the current standard resolution required in infrared thermometry for monitoring postoperative complications(0.1 K).We fabricated,simulated,in vitro tested,and compared three acoustic sensor designs in the 29-43℃(~302-316 K)temperature *** this concept,we demonstrate how our passive metamaterial sensor can open the way toward new zero-power smart medical implant concepts based on acoustic interrogation.

关键词： passive resolution utilize

repellent effects of pongam oil on settlement and oviposition of the common greenhouse whitefly Trialeurodes vaporariorum on chrysanthemum

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Insect Science 2007年第3期14卷 219-224页

作者： roman pAVELA gErHArD HErDA research Institute of Crop production Prague Czech University of Agriculture Prague Czech Republic

The repellent activities, including host deterrence and anti-oviposion, of pongam oil against the adults of the common greenhouse whitefly Trialeurodes vaporariorum Westwood in greenhouses were tested. Chrysanthemum plants treated with different concentrations （0.5%-2.0%） of water-suspended pongam oil showed relatively long-lasting host deterrent and anti-oviposition effects on the adults of greenhouse whitefly. Although the repellent effect declined in time and concentration, strong effects on the reduction of oviposition were found, which lasts, dependent on concentration at least 12 days after application.

关键词： botanical insect control agent oviposition pongam oil repellence Trialeurodes vaporariorum

s cascade reinforcement likely when sympatric tnd allopatric populations exchange migrants？

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Current Zoology 2016年第2期62卷 155-167页

作者： roman YUKILEVICH Fumio AOKI Department of Biology Union College Schenectady NY 12308 Department of Ecology and Evolution Stony Brook University Stony Brook NY 11794

When partially reproductively isolated species come back into secondary contact, these taxa may diverge in mating preferences and sexual cues to avoid maladaptive hybridization, a process known as reinforcement. This phenomenon often leads to reproductive character displacement （rCD） between sympatric and allopatric populations of reinforcing species that differ in their exposure to hybridization. recent discussions have reinvigorated the idea that rCD may give rise to additional speciation between conspecific sympatric and allopatric populations, dubbing the concept ＂cascade reinforcement.＂ Despite some empirical studies supporting cascade reinforcement, we still know very little about the conditions for its evolution. In the present article, we address this question by developing an individual-based population genetic model that explicitly simulates cascade reinforcement when one of the hybridizing species is split into sympatric and allopatric populations. Our results show that when sympatric and allopatric populations reside in the same environment and only differ in their exposure to maladaptive hybridization, migration between them generally inhibits the evolution of cascade by spreading the reinforcement alleles from sympatry into allopatry and erasing rCD. Under these conditions, cascade reinforcement only evolved when migration rate between sympatric and allopatric populations was very low. This indicates that stabilizing sexual selection in allopatry is generally ineffective in preventing the spread of reinforcement alleles. Only when sympatric and allopatric populations experienced divergent ecological selection did cascade reinforcement evolve in the presence of substantial migration. These predictions clarify the conditions for cascade reinforcement and facilitate our understanding of existing cases in nature.

关键词： Dobzhansky-Muller incompatibilities hybrid zones reproductive character displacement reproductive isolation secondary contact sexual isolation speciation