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Determination of the sensible heat effectiveness and pressure loss of a rotary regenerative heat exchanger using CFD

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Building Simulation 2023年第6期16卷 869-887页

作者： Vladimír Zmrhal Petr Zelenský Jindřich Boháč martin Barták Miroslav Kučera roman Vavřička Faculty of Mechanical Engineering Department of Environmental EngineeringCzech Technical University in PragueTechnická416000Prague 6Czech Republic

The paper presents a new method to determine the sensible effectiveness and pressure loss of rotary regenerative heat exchangers using computational fluid dynamics(CFD).It is based on CFD simulations of a single thermal wheel microchannel with a small cross-sectional area and thin walls,with cyclic inlet and outlet boundary *** unique measurement set-ups were designed and built for the experimental measurement of the heat exchanger *** different types of thermal wheels were manufactured,measured,and simulated in ANSYS *** wheels achieve an effectiveness greater than 73%under certain(air flow)conditions,which is the minimum effectiveness required by Ecodesign(in the EU).For the examined exchangers,the effectiveness ranges from 66.5%to 83.3%,depending on the boundary conditions and geometric parameters of the *** highest sensible effectiveness is achieved by heat exchangers with the largest heat exchange surface Ac;on the other hand,these wheels have the largest pressure *** paper discusses the use of a simplifiedε-NTU correlation model for the HVAC systems(typically C*=1).The correlation model and CFD results were compared and found to be different from each *** results of the CFD simulation were compared with measurements to prove that the proposed simulation method can predict the behaviour of the real heat exchanger as a *** was demonstrated that the sensible effectiveness and pressure loss of the rotary heat exchanger predicted by the CFD simulations correspond well to the measured values within the measurement uncertainty±1.3%.The proposed method can be used for the comparison of different rotary regenerative heat exchangers before their manufacturing and for verification that they meet the EU Ecodesign requirements set by the current *** reduces the cost of the initial optimisation and testing of new designs.

关键词： rotary heat exchanger heat wheel microchannel heat recovery sensible effectiveness pressureloss computer fluid dynamics experiment

Brillouin expanded time-domain analysis based on dual optical frequency combs

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Light(Science & Applications) 2024年第8期13卷 1534-1544页

作者： Jae Hyeong Youn Kwang Yong Song Sonia martin-Lopez Miguel Gonzalez-Herraez María r.Fernández-ruiz Dept.of Physics Chung-Ang UniversitySeoulKorea Dept.of Electronics Universidad de AlcaláMadridSpain

Brillouin Optical Time-Domain Analysis(BOTDA)is a widely-used distributed optical fiber sensing technology employing pulse-modulated pump waves for local information retrieval of the Brillouin gain or loss *** spatial resolution of BOTDA systems is intrinsically linked to pulse duration,so high-resolution measurements demand high electronic bandwidths inversely proportional to the *** paper introduces Brillouin Expanded Time-Domain Analysis(BETDA)as a modified BOTDA system,simultaneously achieving high spatial resolution and low detection *** two optical frequency combs(OFCs)with different frequency intervals as pump and probe,local Brillouin gain spectra are recorded by their spectral beating traces in an expanded time domain.A 2-cm-long hotspot located in a 230m single-mode fiber is successfully measured in the time domain with a detection bandwidth of less than 100 kHz using dual OFCs with tailored spectral phase,line spacing,and bandwidth.

关键词： pump optical fiber

Stable analysis on speed-adaptive observer in regenerating mode

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Science China(Technological Sciences) 2012年第1期55卷 213-222页

作者： OUYANGYi MAErZ martin Institute of Electrical Engineering Chinese Academy of Sciences Beijing 100190 China Institute for Integrated Systems and Device Technology ofFraunhofer Erlangen 91058 Germany

Speed-adaptive full-order flux observer is the most promising flux estimator among all the sensorless control ***,conventional speed-adaptive flux observer becomes unstable during regenerating operation at low speed since induction motor is an observable system except dc ***,the instability problem is caused by inappropriate designing of *** on the eigenvalues of extended observer,this paper interprets unstable situation,that the eigenvalues of extended ob-server have a positive real ***,the observer cannot *** the two different solutions for unstable prob-lem-positive real maintaining and current error augment,the proposed method based on the eigenvalue could unify these two solutions,which gives the complete stability condition for speed-adaptive full-order *** does a lot help in observer *** observer configured by this proposed method was verified in the torque controlling of 20 kW induction *** to the experiment result,with appropriate designing of observer,the unstable situation during regeneration mode could be completely overcome.

关键词： sensorless control field orientation induction motor drives instability regenerating mode

The pH of the Apoplast： Dynamic Factor with =unctional Impact Under Stress

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Molecular Plant 2017年第11期10卷 1371-1386页

作者： Christoph-martin Geilfus Division of Controlled Environment Horticulture Faculty of Life Sciences Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences Humboldt-University of Berlin Albrecht-Thaer-Weg 1 14195 Berlin Germany

The apoplast is an interconnected compartment with a thin water-film that alkalinizes under stress. This systemic pH increase may be a secondary effect without functional implications, arising from ion movements or proton-pump regulations. On the other hand, there are increasing indications that it is part of a mechanism to withstand stress. regardless of this controversy, alkalinization of the apoplast has received little attention. The apoplastic pH （PHapo） increases not only during plant-pathogen interactions but also in response to salinity or drought. Not much is known about the mechanisms that cause the leaf apoplast to alkalinize, nor whether, and if so, how functional impact is conveyed. Controversial explanations have been given, and the unusual complexity of pHapo regulation is considered as the primary reason behind this lack of knowledge. A gathering of scattered information revealed that changes in PHapo convey functionality by regulating stomatal aperture via the effects exerted on abscisic acid. Moreover, apoplastic alkalinization may regulate growth under stress, whereas this needs to be verified. In this review, a comprehensive survey about several physiological mechanisms that alkalize the apoplast under stress is given, and the suitability of apoplastic alkalinization as transducing element for the transmission of sensory information is discussed.

关键词： apoplastic fluid alkalinization abscisic acid PM-H^+-ATPase S-Type anion channel malate

Adaptive optical microscopy: the ongoing quest for a perfect image

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Light(Science & Applications) 2014年第1期3卷 243-249页

作者： martin J Booth Department of Engineering Science University of OxfordOxford OX13PJUK Centre for Neural Circuits and Behaviour University of OxfordOxford OX13SRUnited Kingdom School in Advanced Optical Technologies Friedrich-Alexander Universita¨t Erlangen-Nu¨rnberg91052 ErlangenGermany

Adaptive optics is becoming a valuable tool for high resolution microscopy,providing correction for aberrations introduced by the refractive index structure of *** is proving particularly promising for applications that require images from deep within biological tissue *** review recent developments in adaptive microscopy,including methods and applications.A range of advances in different microscope modalities is covered and prospects for the future are discussed.

关键词： aberrations adaptive optics microscopy

Versatile chip-based nanoscopy becomes ready for histopathology assessment

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Light(Science & Applications) 2022年第5期11卷 730-732页

作者： martin Lopez-Garcia Natural and Artificial Photonic Structures Group International Iberian Nanotechnology LaboratoryBraga 4715-330Portugal

Nanoscopy is a mature technology used routinely in life science to obtain images well below the optical diffraction *** the use of nanoscopy in histopathology assessment is very limited mostly due to the low throughput of traditional nanoscopic *** far,Chip-nanoscopy,nanoscopy in which sample illumination is performed by an integrated photonic chip instead of bulk optics,has been shown to provide an enhanced field of view and throughput for cell ***,a new development shows that chip-nanoscopy also offers interesting progress for the study of histological samples offering a complementary technique to electron microscopy for histopathology assessment.

关键词： nanos offering illumination

混凝土及土石坝工程寿命与大坝安全工程经济效益(英文)

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岩土工程学报 2008年第11期30卷 1692-1698页

作者： martin Wieland r.Peter Brenner Chairman ICOLD Committee on Seismic Aspects of Dam DesignPoyry Energy Ltd.Hardturmstrasse 161ZurichSwitzerland Former Chairman ICOLD Committee on Dam FoundationsConsultantRosenstrasse 8WeinfeldenSwitzerland

大坝安全与大坝结构的物理状态密切相关,而大坝的物理状态取决于维护及加固工程。在一定程度上,维修维护工程控制了大坝结构的使用年限。大坝安全措施带来的效益很大程度上取决于维护、监测及管理工程的投资。第一部分讨论了诸如老化、... 详细信息

大坝安全与大坝结构的物理状态密切相关,而大坝的物理状态取决于维护及加固工程。在一定程度上,维修维护工程控制了大坝结构的使用年限。大坝安全措施带来的效益很大程度上取决于维护、监测及管理工程的投资。第一部分讨论了诸如老化、维护、缺陷的影响,以及可能使用年限内对混凝土和土石坝及其基础的设计要求;第二部分评价了有关大坝安全设计与安全措施的投资效益,如维护、监测及管理。结果表明,投资效益不直接源于货币收入,而是体现在良好的安全运行、原建筑物的投资保护、避免溃坝带来的经济损失等方面,同时提高了公众意识,降低了下游地区的风险。

关键词：大坝安全大坝安全效益大坝老化大坝寿命维护

Progress on band structure engineering of twisted bilayer and two-dimensional moiré heterostructures

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Chinese Physics B 2020年第12期29卷 5-16页

作者： Wei Yao martin Aeschlimann Shuyun Zhou Department of Physics and research Center OPTIMAS University of Kaiserslautern67663 KaiserslauternGermany State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics Tsinghua UniversityBeijing 100084China

Artificially constructed van der Waals heterostructures(vdWHs)provide an ideal platform for realizing emerging quantum phenomena in condensed matter *** methods for building vdWHs have been developed:stacking two-dimensional(2D)materials into a bilayer structure with different lattice constants,or with different *** interlayer coupling stemming from commensurate or incommensurate superlattice pattern plays an important role in vdWHs for modulating the band structures and generating new electronic *** this article,we review a series of novel quantum states discovered in two model vdWH systems—graphene/hexagonal boron nitride(hBN)hetero-bilayer and twisted bilayer graphene(tBLG),and discuss how the electronic structures are modified by such stacking and *** also provide perspectives for future studies on hetero-bilayer materials,from which an expansion of 2D material phase library is expected.

关键词： twisted bilayer graphene van der Waals heterostructure band structure engineering

Conditioned duality between supercontinental’assembly’and’breakup’LIPs

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Geoscience Frontiers 2020年第5期11卷 1635-1649页

作者： martin B.Klausen Department of Earth Sciences Stellenbosch UniversityPrivate Bag X1MatielandSouth Africa

A compilation of 178 more precise ages on 10 potential Large Igneous Provinces(LIPs)across southern Africa,is compared to Earth’s supercontinental cycles,where 5 more prominent LIP-events all formed during the assembly of supercontinents,rather than during *** temporal bias is confirmed by a focused review of field relationships,where these syn-assembly LIPs formed behind active continental arcs;whereas,the remaining postassembly-and likely breakup-related-LIPs never share such *** the possibility of two radically different LIP-types,only the two younger breakup events(the Karoo LIP and Gannakouriep Suite)produced basalts with more enriched asthenospheric OIB-signatures;whereas,all assembly LIPs produced basalts with stronger lithospheric,as well as more or less primitive asthenospheric,signatures.A counterintuitive observation of Precambrian breakup LIPs outcropping as smaller fragments that are more peripherally located along craton margins,compared to assembly LIPs as well as the Phanerozoic Karoo breakup LIP,is explained by different preservation potentials during subsequent supercontinental ***,further accentuating radical differences between(1)breakup LIPs,preferentially intruding along what evolves to become volcanic rifted margins that are more susceptible to deformation within subsequent orogens,and(2)assembly LIPs,typically emplaced along backarc rifts within more protected cratonic interiors.A conditioned duality is proposed,where assembly LIPs are primarily sustained by thermal blanketing(as well as local arc hydration and rifting)below assembling supercontinents and breakup LIPs more typically form above impinging mantle *** a duality is further related to an overall dynamic Earth model whereby predominantly supercontinent-orientated ocean lithospheric subduction establishes/revitalizes large low shear velocity provinces(LLSVPs)during assembly LIP-activity,and heating of such LLSVPs by the Earth’s core subsequ

关键词： Large igneous provinces Extrovert plate tectonics LLSVP Mantle dynamics Geochemical discrimination