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Almost nonnegative curvature operator and cohomology rings

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Frontiers of Mathematics in China 2016年第5期11卷 1259-1274页

作者： martin HERRMANN Fakultat fur Mathematik Karlsruher Institut fur Technologie Kaiserstraβe 89-93 76133 Karlsruhe Germany

We give a survey of results on the construction of and obstructions to metrics of almost nonnegative curvature operator on closed manifolds and results on the cohomology rings of closed, simply-connected manifolds with a lower curvature and upper diameter bound. The latter is motivated by a question of Grove whether these condition imply finiteness of rational homotopy types. This question has answers by F. Fang-X. Rong, B. Totaro and recently A. Dessai and the present author.

关键词： Nonnegative curvature homogeneous spaces curvature operator almost nonnegative curvature

Binary operations for homotopy groups with coefficients

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Science China Mathematics 2018年第9期61卷 1543-1552页

作者： martin Arkowitz Department of Mathematics Dartmouth College

We define and study binary operations for homotopy groups with coefficients, and give conditions to prove that certain binary operations are the homomorphic image of the generalized Whitehead product. This allows carrying over properties of the generalized Whitehead product to these operations. We discuss two classes of binary operations, i.e., the Whitehead products and the torsion products. We also introduce a new class of operations called Ext operations and determine some of its properties. Then we compare the torsion product with the Whitehead product in a special case, and prove that the smash product of two Moore spaces has the homotopy type of a wedge of two Moore spaces.

关键词： homotopy groups with coefficients binary operations the generalized Whitehead product Whitehead products torsion products

A multi-shot target wheel assembly for high-repetition-rate, laser-driven proton acceleration

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High Power Laser Science and Engineering 2024年第2期12卷 87-94页

作者： J.Penas A.Bembibre D.Cortina-Gil L.martin A.Reija C.Ruiz M.Seimetz A.Alejo J.Benlliure Instituto Galego de Fisica de Altas Enerxias Universidade de Santiago de CompostelaSantiago de CompostelaSpain Laboratorio Laser de Aceleracion y Aplicaciones RIAIDTUniversidade de Santiago de CompostelaSantiago de CompostelaSpain Instituto Universitario de Física Fundamental y Matematicas y Dpto.de Didactica de la Matematica y de las Ciencias Experimentales Universidad de SalamancaSalamancaSpain Instituto de Instrumentación para Imagen Molecular(I3M) CSIC-Universitat Politecnica de ValenciaValenciaSpain

A multi-shot target assembly and automatic alignment procedure for laser–plasma proton acceleration at high repetition rate are *** assembly is based on a multi-target rotating wheel capable of hosting more than 5000 targets,mounted on a 3D motorized stage to allow rapid replenishment and alignment of the target material between laser *** automatic alignment procedure consists of a detailed mapping of the impact positions at the target surface prior to the irradiation that ensures stable operation of the target,which alongside the purpose-built design of the target wheel,enables operation at rates up to 10 *** and continuous laser-driven proton acceleration at 10 Hz is demonstrated,with observed cut-off energy stability about 15%.

关键词： high repetition rate laser-plasma acceleration multi-shot operation proton source target assembly

Relevance of plasma lipoproteins and small metabolites in assessment of nutritional status among patients with severe injuries

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Journal of Intensive Medicine 2024年第4期4卷 496-507页

作者： Esmee A.H.Verheul Suzan Dijkink Pieta Krijnen Aswin Verhoeven martin Giera Roula Tsonaka Jochem M.Hoogendoorn Sesmu M.Arbous Ron Peters Inger B.Schipper Department of Trauma Surgery Leiden University Medical CenterLeidenThe Netherlands Acute Care Network West Netherlands LeidenThe Netherlands Center for Proteomics and Metabolomics Leiden University Medical CenterLeidenThe Netherlands Department of Biomedical Data Sciences Leiden University Medical CenterLeidenThe Netherlands Department of General Surgery Haaglanden Medical CenterThe HagueThe Netherlands Department of Intensive Care Leiden University Medical CenterLeidenThe Netherlands Department of Intensive Care Haaglanden Medical CenterThe HagueThe Netherlands

Background:This study aimed to identify plasma lipoproteins and small metabolites associated with high risk of malnutrition during intensive care unit(ICU)stay in patients with severe ***:This observational prospective exploratory study was conducted at two level-1 trauma centers in the *** patients(aged≥18 years)who were admitted to the ICU for more than 48 h between July 2018 and April 2022 owing to severe injuries(polytrauma,as defined by Injury Severity Scores of≥16)caused by blunt trauma were eligible for *** least squares discriminant analysis was used to analyze the relationship of 112 lipoprotein-related components and 23 small metabolites with the risk of malnutrition(mod-ified Nutrition Risk in Critically Ill score).Malnutrition was diagnosed based on Subjective Global Assessment *** relationship of lipoprotein properties and small metabolite concentrations with malnutrition(during ICU admission)was evaluated using mixed effects logistic ***:Overall,51 patients were ***(very)low-density lipoprotein([V]LDL)(free)cholesterol and phospholipid levels,low particle number,and higher levels of LDL triglycerides were associated with a higher risk of malnutrition(variable importance in projection[VIP]value>1.5).Low levels of most(V)LDL and intermediate-density lipoprotein subfractions and high levels of high-density lipoprotein Apo-A1 were associated with the diagnosis of malnutrition(VIP value>1.5).Increased levels of dimethyl sulfone,trimethylamine N-oxide,creatinine,N,N-dimethylglycine,and pyruvic acid and decreased levels of creatine,methionine,and acetoacetic acid were also indicative of malnutrition(VIP value>1.5).Overall,14 lipoproteins and 1 small metabolite were significantly associated with a high risk of malnutrition during ICU admission(P<0.05);however,the association did not persist after correcting the false discovery rate(P=0.35 for all).Conclusion:Increased triglyceride in sev

关键词： Trauma Severely injured Metabolites Lipoproteins Malnutrition Nutritional status

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

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

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

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

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.