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Gold as a Potential Contrast Agent for Dual-Energy CT

Advances in Molecular Imaging 2013年第4期3卷 37-42页

作者： Radko Krissak martin Elgert Bjorn Kusch ralph Hünerbein Department of Diagnostic and Interventional Radiology Hufeland Klinikum GmbHBad LangensalzaGermany

Purpose: The K-edge of gold (81 keV) is located within the energy range of diagnostic CT. This might be advantageous for material differentiation in dual-energy CT (DECT). The aim of this in vitro study was to compare the differentiation between iodine or gold and body tissues using DECT at different kV spectra. Methods and Materials: A water filled tank phantom containing specimens with iodine (iopamidol), gold (sodium aurothiomalate), compact bone (compact porcine bone) and porcine muscle was scanned using a dual source CT (Definition, Siemens Healthcare). Consecutive scans were performed at 80 kVp, 100 kVp, 120 kVp and 140 kVp with constant mAs settings. The mean attenuation values of the specimens were measured, and differences in calculated dual-energy ratios (DEratio) between body tissues and iodine or gold were determined for different DE spectra. Results: The attenuation of gold increased compared to 80 kVp at higher kVp-settings, while the attenuation of all other specimens decreased. The calculated DEratios at 80/100 kVp, 80/120 kVp and 80/140 kVp were 1.31, 1.62 and 1.91 for iodine, 0.89, 0.88 and 0.92 for gold, 1.20, 1.39 and 1.45 for compact bone, 1.01, 1.03 and 1.08 for muscle. The differences between the DEratios 80/100 kVp, 80/120 kVp and 80/140 kVp were 0.11, 0.23 and 0.46 for iodine and bone, 0.31, 0.51 and 0.53 for gold and bone, 0.29, 0.59 and 0.83 for iodine and muscle, 0.12, 0.15 and 0.16 for gold and muscle. Conclusion: DEratio of gold remains relatively stable along the energy spectrum of diagnostic CT and allows a reliable material differentiation between gold and bone already at contiguous low tube voltage settings (80 kV and 100 kV). Thus, gold might have a potential as a contrast agent for DECT.

关键词： Gold Computed Tomography Dual-Energy Contrast Agent K-Edge

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Applicability of high-temperature cooling systems in different European countries from the view of the condensation risk

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Building Simulation 2021年第5期14卷 1453-1466页

作者： Vladimir Zmrhal martin Bartak Czech Technical University in Prague Faculty of Mechanical EngineeringDepartment of Environmental Engineering Technicka 416000 Prague 6Czech Republic

Due to the different approaches in determining the ventilation airflow rate per person for workspaces,where high-temperature air conditioning systems are used for air conditioning,problems with the condensation of water vapour on the cold surfaces of the system can *** article analyses the risk of condensation in various European cities using the available climatic *** with cooling ceilings and cooling beams with a ventilation device operating in parallel are taken into *** ventilation airflow rates per person were *** the example of a room equipped with high-temperature cooling,an energy simulation calculation is performed,which includes a ventilation and air-conditioning system with the possibility of capacity *** is clear from the results that the condensation of water vapour can be prevented by technical measures at the cost of reducing the cooling capacity,which can affect the achievement of the thermal comfort of those *** the end,suitable solutions are discussed,which should already be adopted at the time the device is designed so that the risk of condensation is not a major obstacle in the operation of these energy-efficient *** irreplaceable role in the operation of high-temperature cooling systems is played by a measurement and control system with a suitable algorithm to prevent condensation.

关键词： ventilation air-conditioning cooled ceilings chilled beams low energy cooling risk of condensation

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Experimental and Numerical Investigation of Centrifugal Pumps with Asymmetric Inflow Conditions

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Journal of Thermal Science 2015年第6期24卷 516-525页

作者： Sten Mittag martin Gabi Institute of Fluid Machinery Karlsruhe Institute of Technology KIT

Most of the times pumps operate off best point *** are changes of operating conditions,modifications,pollution and wearout or *** consequences non-rotational symmetric flows,transient operational conditions,increased risk of cavitation,decrease of efficiency and unpredictable wearout can *** construction components of centrifugal pumps,in particular intake elbows,contribute to this *** elbows causes additional losses and secondary flows,hence non-rotational velocity distributions as intake profile to the centrifugal *** a result the impeller vanes experience permanent changes of the intake flow angle and with it transient flow conditions in the blade *** paper presents the first results of a project,experimentally and numerically investigating the consequences of non-rotational inflow to leading edge flow conditions of a centrifugal *** two pumpintake-elbow systems are compared,by only altering the intake elbow geometry:a common single bended 90°elbow and a numerically optimized elbow(improved regarding rotational symmetric inflow conditions and friction coefficient).The experiments are carried out,using time resolved stereoscopic PIV on a full acrylic pump with refractions index matched(RIM)working *** allows transient investigations of the flow field simultaneously for all blade leading *** CFD results are validated and used to further support the investigation *** comparing an analog pump system with ideal inflow conditions.

关键词： non-rotational symmetric inflow centrifugal pump intake elbow PIV RIM CFD

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CFD-DEM simulation of turbulence modulation in horizontal pneumatic conveying

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Particuology 2017年第2期15卷 15-24页

作者： Mohammadreza Ebrahimi martin Crapper Institute for Infrastructure and Environment School of Engineering The University of Edinburgh The King's Buildings Edinburgh EH9 3JL UK Department of Mechanical and Construction Engineering Northumbria University Ellison Place Newcastle-upon-Tyne NE1 8ST UK

A study is presented to evaluate the capabilities of the standard k–ε turbulence model and the k–ε turbulence model with added source terms in predicting the experimentally measured turbulence modulation due to the presence of particles in horizontal pneumatic conveying, in the context of a CFD–DEM Eulerian–Lagrangian simulation. Experiments were performed using a 6.5-m long, 0.075-m diameter horizontal pipe in conjunction with a laser Doppler anemometry （LDA） system. Spherical glass beads with two sizes, 1.5 and 2 mm, were used. Simulations were performed using the commercial discrete element method software EDEM, coupled with the computational fluid dynamics package FLUENT. Hybrid source terms were added to the conventional k–ε turbulence model to take into account the influence of the dispersed phase on the carrier phase turbulence intensity. The simulation results showed that the turbulence modulation depends strongly on the model parameter Cε3. Both the standard k–ε turbulence model and the k–ε turbulence model with the hybrid source terms could predict the gas phase turbulence intensity trend only generally. A noticeable discrepancy in all cases between simulation and experimental results was observed, particularly for the regions close to the pipe wall. It was also observed that in some cases the addition of the source terms to the k–ε turbulence model did not improve the simulation results when compared with those of the standard k–ε turbulence model. Nonetheless, in the lower part of the pipe where particle loading was greater due to gravitational effects, the model with added source terms performed somewhat better.

关键词： Turbulence modulation Pneumatic conveying Eulerian-Lagrangian approach Laser Doppler anemometry

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A force-compensated compliant MEMS-amplifier with electrostatic anti-springs

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Microsystems & Nanoengineering 2023年第3期9卷 235-244页

作者： Philip Schmitt martin Hoffmann Microsystems Technology Ruhr-Universität BochumUniversitätsstr.15044801 BochumGermany

In this paper,an electrostatic compliant mechanical amplifier intended for force-compensated displacement amplification in MEMS sensor applications is ***,mechanical transformers that enhance a small input displacement into a large output displacement generate large forces at the input of the *** microsystem proposed here allows for the reduction and compensation of the input stiffness of the amplifier and any mechanical components connected to it while providing a constant amplification ratio at the same *** amplifying mechanism features bidirectional electrostatic anti-springs enabling the control of the stiffness by applying a constant DC *** electrode design of the anti-springs and its influence on the force-displacement characteristic,the side instability and the maximal displacement are studied through analytical approaches and supported by FEA and by *** on the derived models,a compliant electromechanical amplifier is developed,featuring an amplification ratio of *** this amplifier the initial input stiffness of 422 N/m could be reduced to 6.8 N/m by applying a voltage of 100 *** an additional application,we show how the amplifier can be used as a mechanical force sensor with tuneable sensitivity,where the forces at the input are transformed into large output *** experiments,we show how the sensitivity can be adjusted and increased by a factor of 25 by applying a voltage at the anti-springs.

关键词： amplifier electrostatic spring

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Froth flotation of scheelite – A review

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International Journal of Mining Science and Technology 2018年第3期28卷 373-384页

作者： Nathalie Kupka martin Rudolph Helmholtz Zentrum Dresden Rossendorf (HZDR) Helmholtz Institute Freiberg for Resource Technology (HIF)

Froth flotation of scheelite has regained new focus since the 2010s and research regarding floatability and reagents has made great progress over the years. The main objective was and remains the selective flotation of scheelite from other calcium-bearing minerals, in particular calcite, fluorite and apatite. Due to similar properties, most attempts have limited success or only specific application(linked to a type of ore or a location). This article aims at reviewing all general physical-chemical information on froth flotation of scheelite, including electrokinetic properties, influence of p H and already existing reagents as well as ones still under examination. It appears that chelating or mixed collectors and modified versions of sodium silicate and quebracho hold great promise for scheelite flotation, while the use of said depressants and/or promoters seems inevitable.

关键词： Scheelite Froth flotation Calcium-bearing minerals Selectivity challenges Promising reagents

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MODELING SOCCER BY MEANS OF RELATIVE PHASE

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Journal of Systems Science & Complexity 2013年第1期26卷 14-20页

作者： SIEGLE Malte LAMES martin TU Munchen Department for Training and Computer Science in Sports

Soccer is a complex ***,appropriate(nontrivial) models have to be applied to be able to analyze the behavior of the teams on the *** study analyzed the World Cup Final 2006 between France and Italy by means of relative *** longitudinal and lateral positions of all 20 outfield players were used to calculate relative phase by Hilbert *** team-,group-,and attacker-fullbacks couplings showed that soccer is clearly an in-phase *** of the relative phase structure helped to identify scoring opportunities of the attacking ***,analyses of the relative phase structure can help to understand the complexity of soccer.

关键词： Perturbations relative phase soccer.

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Enhanced nitric oxide production is a universal response to hypoxic stress

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National Science Review 2018年第4期5卷 532-533页

作者： martin Feelisch Clinical & Experimental Sciences and Integrative Physiology and Critical Illness Group Faculty of Medicine Southampton General Hospital and Institute for Life Sciences University of Southampton NSR

Life at high altitude poses a formidable challenge to human physiology because every breath of thin air inhaled contains less oxygen(O2)per volume than air at sea level,causing the resultant drop in O2 pressure in blood to limit performance and threaten *** short-term adjustments to hypoxia(acclimatization)including increased erythropoiesis ensure total

关键词： Enhanced nitric oxide production is a universal response to hypoxic stress

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Using the DEM-CFD method to predict Brownian particle deposition in a constricted tube

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Particuology 2014年第4期12卷 94-106页

作者： Florian Chaumeil martin Crapper School of Engineering The University of EdinburghEdinburgh EH9 3JLUnited Kingdom

Modelling of the agglomeration and deposition on a constricted tube collector of colloidal size particles immersed in a liquid is investigated using the discrete element method （DEM）. The ability of this method to represent surface interactions allows the simulation of agglomeration and deposition at the particle scale. The numerical model adopts a mechanistic approach to represent the forces involved in colloidal suspensions by including near-wall drag retardation, surface interaction and Brownian forces. The model is implemented using the commercially available DEM package EDEM 2.3~, so that results can be repli- cated in a standard and user-friendly framework. The effects of various particle-to-collector size ratios, inlet fluid flow-rates and particle concentrations are examined and it is found that deposition efficiency is strongly dependent on the inter-relation of these parameters. Particle deposition and re-suspension mechanisms have been identified and analyzed thanks to EDEM＇s post processing capability. One-way coupling with computational fluid dynamics （CFD） is considered and results are compared with a two- way coupling between EDEM 2.3 and FLUENT 12.1. It is found that two-way coupling requires circa 500% more time than one-way coupling for similar results.

关键词： Discrete element method DEM Colloids Agglomeration Deposition Simulation

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Sharpening emitter localization in front of a tuned mirror

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Light(Science & Applications) 2018年第1期7卷 71-78页

作者： Hannah S.Heil Benjamin Schreiber ralph Götz Monika Emmerling Marie-Christine Dabauvalle Georg Krohne Sven Höfling martin Kamp Markus Sauer Katrin G.Heinze Rudolf Virchow Center Research Center for Experimental BiomedicineUniversity of WürzburgJosef-Schneider-Str.297080 WürzburgGermany Department of Biotechnology and Biophysics BiozentrumUniversity of WürzburgAm Hubland97074 WürzburgGermany Technische Physik Physikalisches Institut and Wilhelm Conrad Röntgen-Center for Complex Material SystemsUniversity of WürzburgAm Hubland97074 WürzburgGermany Division of Electron Microscopy BiozentrumUniversity of WürzburgAm Hubland97074 WürzburgGermany SUPA School of Physics and AstronomyUniversity of St AndrewsSt Andrews KY169SSUK

Single-molecule localization microscopy(SMLM)aims for maximized precision and a high signal-to-noise *** features can be provided by placing the emitter in front of a metal-dielectric nanocoating that acts as a tuned mirror2–***,we demonstrate that a higher photon yield at a lower background on biocompatible metal-dielectric nanocoatings substantially improves SMLM performance and increases the localization precision by up to a factor of *** resolution improvement relies solely on easy-to-fabricate nanocoatings on standard glass coverslips and is spectrally and spatially tunable by the layer design and wavelength,as experimentally demonstrated for dual-color SMLM in cells.

关键词： emitter mirror tunable

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