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Science China Mathematics 2024年第7期67卷 1641-1664页

作者： Jinye Shen Fanhai Zeng martin Stynes School of Mathematics Southwestern University of Finance and EconomicsChengdu611130China School of Mathematics Shandong UniversityJinan250100China Applied and Computational Mathematics Division Beijing Computational Science Research CenterBeijing100193China

Fractional initial-value problems(IVPs) and time-fractional initial-boundary value problems(IBVPs), each with a Caputo temporal derivative of order α ∈(0, 1), are considered. An averaged variant of the well-known L1 scheme is proved to be O(N^(-2)) convergent for IVPs on suitably graded meshes with N points, thereby improving the O(N^(-(2-α))) convergence rate of the standard L1 scheme. The analysis relies on a delicate decomposition of the temporal truncation error that yields a sharp dependence of the order of convergence on the degree of mesh grading used. This averaged L1 scheme can be combined with a finite difference or piecewise linear finite element discretization in space for IBVPs, and under a restriction on the temporal mesh width, one gets again O(N^(-2)) convergence in time, together with O(h^(2)) convergence in space,where h is the spatial mesh width. Numerical experiments support our results.

关键词： time-fractional subdiffusion averaged L1 scheme

Particle Size Optimization of Thermochemical Salt Hydrates for High Energy Density Thermal Storage

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Energy & Environmental Materials 2024年第2期7卷 326-333页

作者： Andrew martin Drew Lilley Raνi Prasher Sumanjeet Kaur Energy Technologies Area Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Department of Mechanical Engineering UC BerkeleyBerkeleyCA 94720USA

Thermal energy storage(TES)solutions offer opportunities to reduce energy consumption,greenhouse gas emissions,and ***,they can help reduce the peak load and address the intermittency of renewable energy sources by time shifting the load,which are critical toward zero energy *** materials(TCMs)as a class of TES undergo a solid-gas reversible chemical reaction with water vapor to store and release energy with high storage capacities(600 kWh m^(-3))and negligible self-discharge that makes them uniquely suited as compact,stand-alone units for daily or seasonal ***,TCMs suffer from instabilities at the material(salt particles)and reactor level(packed beds of salt),resulting in poor multi-cycle efficiency and high-levelized cost of *** this study,a model is developed to predict the pulverization limit or Rcrit of various salt hydrates during thermal *** is critical as it provides design rules to make mechanically stable TCM composites as well as enables the use of more energy-efficient manufacturing process(solid-state mixing)to make the *** model is experimentally validated on multiple TCM salt hydrates with different water content,and effect of Rcrit on hydration and dehydration kinetics is also investigated.

关键词： high energy density hydration kinetics long-term cycling thermal energy storage thermochemical materials

Experimental investigation of radiative heat propagation in a simplified generic packed bed

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Particuology 2024年第5期88卷 149-160页

作者： Matthias Tyslik Lukas Pörtner Siegmar Wirtz martin Schiemann Institute of Energy Plant Technology Ruhr-University Bochum44780 BochumGermany

A novel test rig for the investigation of radiative heat transfer in packed beds has been developed and is introduced with representative experimental *** individual components and the calibration are *** generic packed bed is realized in a simplified way by an arrangement of parallel rods,which represent particles in *** this arrangement,electrically heated rods provide the radiation propagating through the rod array to heat the passive counterparts.A sophisticated temperature-control scheme with a large number of thermocouples and infrared-imaging provides in-depth information about heat transfer in the *** radiation intensities are determined with a Fourier-transform infrared spectroscopy,which has been modified and validated for this specific *** order to compare the influence of different surface properties of particles on the heat propagation and surface reflections,rod samples made of stainless steel and magnesium oxide are *** influence of material properties becomes clearly visible by comparing the high radiation intensities resulting from a stainless steel rod array to the same geometry built from magnesium oxide *** addition,the influence of the surface properties is particularly evident in the infrared images since the reflections are significantly higher for the stainless steel samples than for the magnesium oxide *** experimental results in the current work demonstrate the ability of the test rig to provide data with a well-defined accuracy as a validation base for numerical radiation simulations in packed beds.

关键词： Thermal radiation Spectral reflections Fourier-transform infrared spectroscopy

Arabidopsis photoperiodic regulator CONSTANS feeds back to control the circadian clock

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Molecular Plant 2024年第9期17卷 1338-1340页

作者： Abril San martin Marcelo Javier Yanovsky Instituto de Investigaciones Bioquimicas de Buenos Aires(Fundacion Instituto Leloir-CONICET) Av.Patricias Argentinas 435Buenos AiresC1405BWE

Human beings live in a world defined by daily cycles of light and darkness caused by the Earth's rotation around its ***,like most living organisms,have evolved internal circadian clocks that time biological processes in anticipation of these daily environmental changes(Young and Kay,2001).The plant clock relies on core genes encoding transcription factors(TFs),which regulate each other's expression through intricate networks of interlocking transcriptional-translational feedback loops(Nohales and Kay,2016).These loops ultimately control the expression of thousands of genes,allowing plants to adapt to daily fluctuations in light,temperature,and humidity(Covington et al.,2008).In addition to daily rhythms,the Earth experiences yearly seasonal cycles marked by longer,warmer days in spring and summer,followed by shorter,cooler days in autumn and *** changes in day length and temperature intensify with distance from the ***,the ability of plants to adjust their growth and development in anticipation of seasonal changes determines their latitudinal distribution(McMillan,1960).

关键词： circadian seasonal Arabidopsis

Convergent Data-Driven Regularizations for CT Reconstruction

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Communications on Applied Mathematics and Computation 2024年第2期6卷 1342-1368页

作者： Samira Kabri Alexander Auras Danilo Riccio Hartmut Bauermeister martin Benning Michael Moeller martin Burger Helmholtz Imaging Deutsches Elektronen-Synchrotron DESYNotkestr.8522607 HamburgGermany Institute for Vision and Graphics University of SiegenAdolf-Reichwein-Straße 2a57076 SiegenGermany School of Mathematical Sciences Queen Mary University of LondonMile End RoadLondon E14NSUK The Alan Turing Institute British Library96 Euston RdLondon NW12DBUK Fachbereich Mathematik Universitat HamburgBundesstrasse 5520146 HamburgGermany

The reconstruction of images from their corresponding noisy Radon transform is a typical example of an ill-posed linear inverse problem as arising in the application of computerized tomography(CT).As the(naive)solution does not depend on the measured data continuously,regularization is needed to reestablish a continuous *** this work,we investigate simple,but yet still provably convergent approaches to learning linear regularization methods from *** specifically,we analyze two approaches:one generic linear regularization that learns how to manipulate the singular values of the linear operator in an extension of our previous work,and one tailored approach in the Fourier domain that is specific to *** prove that such approaches become convergent regularization methods as well as the fact that the reconstructions they provide are typically much smoother than the training data they were trained ***,we compare the spectral as well as the Fourier-based approaches for CT-reconstruction numerically,discuss their advantages and disadvantages and investigate the effect of discretization errors at differentresolutions.

关键词： Inverse problems Regularization Computerized tomography(CT) Machine learning

A numerical and experimental comparison of heat transfer in a quasi two-dimensional packed bed

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Particuology 2024年第1期84卷 136-144页

作者： Matthias Tyslik Mirko Ebert martin Schiemann Siegmar Wirtz Christian Lessig Department of Energy Plant Technology Ruhr-University BochumGermany Institute for Simulation and Graphics Otto-von-Guericke-Universität MagdeburgGermany

Heat transfer plays a major role in many industrial processes taking place in packed *** accurate and reliable simulation of the heat exchange between particles is therefore crucial for a reliable operation and to optimize the processes in the *** discrete ordinates method(DOM)provides an established numerical technique to model radiative heat transfer in granular media that offers the possibility to consider the directional dependence of the radiation *** this work,DOM is compared with Monte Carlo ray tracing,which provides an alternative method for heat transfer ***-rically simple configurations are used to investigate the influence of the angular discretization on the accuracy of the results and the computation time in both *** obtained insights are then transferred to a more complex configuration of a quasi two-dimensional test rig consisting of metal rods for which also experimental results are *** results show that both DOM and Monte Carlo ray tracing allow for an accurate simulation of heat transfer in packed *** Carlo ray tracing requires thereby computation times that are surprisingly competitive(although still somewhat slower)compared to DOM and allows for an easier computation of highly accurate reference *** our preliminary comparison to the experimental test rig,Monte Carlo ray tracing also provides the advantage that it can more easily model highly specular materials such as stainless *** methods are comparable for diffuse materials such as magnesium oxide.

关键词： Heat transfer Discrete ordinates method Monte Carlo ray tracing

治疗时间对氯胺酮抗抑郁作用影响的研究概况及未来展望

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中华诊断学电子杂志 2018年第3期6卷 151-156页

作者：李申李洁田红军 Albert Leemon walter martin 禚传君天津医科大学精神卫生研究所天津市精神卫生中心南开大学附属安定医院 300222 天津医科大学精神卫生学系 300070 Clinical Affective Neuroimaging Laboratory Otto von Guericke University Department of Psychiatry and Psychotherapy University of Tübingen 温州市第七人民医院 325000

抑郁障碍是一种常见的严重精神疾病,具有高致残率和致死率,给社会和家庭造成严重负担。目前,近一半抑郁症患者无法得到有效的治疗。在临床实践中,可以广泛观察到氯胺酮具有明显缓解抑郁症状的作用,然而对其抗抑郁机理的研究尚不明确。... 详细信息

抑郁障碍是一种常见的严重精神疾病,具有高致残率和致死率,给社会和家庭造成严重负担。目前,近一半抑郁症患者无法得到有效的治疗。在临床实践中,可以广泛观察到氯胺酮具有明显缓解抑郁症状的作用,然而对其抗抑郁机理的研究尚不明确。笔者主要着眼于氯胺酮抗抑郁作用机理的相关研究进展,重点关注氯胺酮抗抑郁作用的短暂急性期和持续的延迟期机制的复杂相互作用的生物学基础,根据已有文献和前期研究结果提出可行的预设方案,旨在为氯胺酮抗抑郁作用的临床应用提供科学依据。

关键词：氯胺酮抑郁症时间 N-甲基-D-天冬氨酸受体

Time trends and outcomes of gastrostomy placement in a Swedish national cohort over two decades

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World Journal of Gastroenterology 2024年第10期30卷 1358-1367页

作者： martin Löfling Skogar Magnus Sundbom Department of Surgical Sciences Uppsala UniversityUppsala 75185Sweden

BACKGROUND Percutaneous endoscopic gastrostomy(PEG)and laparoscopically inserted gastrostomy have become the gold standard for adult patients and children,respectively,requiring long-term enteral nutrition ***-related mortality is a rare event,often reported to be zero in smaller *** data on 30-d mortality and long-term survival rates after gastrostomy placement are scarce in the *** To study the use of gastrostomies in Sweden from 1998-2019 and to analyze procedure-related mortality and short-term(<30 d)and long-term *** In this retrospective,population-based cohort study,individuals that had received a gastrostomy between 1998-2019 in Sweden were *** were identified in the Swedish National Patient Register,and survival analysis was possible by cross-referencing the Swedish Death *** cohort was divided into three age groups:Children(0-18 years);adults(19-64 years);and elderly(≥65 years).Kaplan-Meier with log-rank test and Cox regression were used for survival *** In total 48682 individuals(52%males,average age 60.9±25.3 years)were *** cohort consisted of 12.0%children,29.5%adults,and 58.5%*** increased use of gastrostomies was observed during the study period,from 13.7/100000 to 22.3/100000 individuals(P<0.001).The use of PEG more than doubled(about 800 to 1800/year),with a corresponding decrease in open gastrostomy(about 700 to 340/year).Laparoscopic gastrostomy increased more than ten-fold(about 20 to 240/year).Overall,PEG,open gastrostomy,and laparoscopic gastrostomy constituted 70.0%(n=34060),23.3%(n=11336),and 4.9%(n=2404),***-related mortality was 0.1%(n=44)overall(PEG:0.05%,open:0.24%,laparoscopic:0.04%).The overall 30-d mortality rate was 10.0%(PEG:9.8%,open:12.4%,laparoscopic:1.7%)and decreased from 11.6%in 1998-2009 vs 8.5%in 2010-2019(P<0.001).One-year and ten-year survival rates for children,adults,and elderly were 93.7%,67.5%,a

关键词： Gastrostomy Percutaneous endoscopic gastrostomy Dysphagia Enteral nutrition Long-term Survival Complication

Semi-analytical calculation model for friction of polymers on the example of POM|PE-UHMW and steel|PE-UHMW

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Friction 2024年第10期12卷 2355-2369页

作者： André BERGMANN Jens SUMPF Niels DALLINGER martin MONEKE Markus GOLDER Professorship of Conveying Engineering and Materials Handling Chemnitz University of TechnologySachsen 09126Germany Institute of Plastics Engineering Darmstadt University of Applied SciencesDarmstadt 64295Germany

In this paper,a semi-analytical calculation model for the coefficient of friction(COF)of single spherical protrusions is *** allows the prediction of the deformative friction part(μ_(def))and adhesive friction part(μ_(def))of the friction pairings steel|polyethylene with ultra-high molecular weight(PE-UHMW)and polyoxymethylene(POM)|*** experimental studies included unlubricated friction tests,which served to determine the total COF(μ_(def)),as well as tests being lubricated with silicone oil,from whichμ_(def)is *** on the verification tests,it could be shown that both states of lubrication result in the same deformation and that the relationship between the rear angle(w)andμ_(def)postulated in the calculation model is ***,friction tests with segmented spheres were carried out,which allow a specific variation of *** can be concluded that for both pairings theμ_(def)is generally of minor significance(approx.1/3μ_(tot))and the influence of theμ_(adh)predominates(approx.2/3μ_(tot))the friction *** themtot decreases with increasing contact pressure especially in the low pressure range and depends on the form of motion(continuous and discontinuous).

关键词： tribology friction polymers model contact polyoxymethylene(POM) polyethylene with ultra-high molecular weight(PE-UHMW)

A Tutorial Review of the Solar Power Curve: Regressions, Model Chains, and Their Hybridization and Probabilistic Extensions

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Advances in Atmospheric Sciences 2024年第6期41卷 1023-1067页

作者： Dazhi YANG Xiang’ao XIA martin János MAYER School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150001HeilongjiangChina Key Laboratory for Middle Atmosphere and Global Environment Observation(LAGEO) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Department of Energy Engineering Faculty of Mechanical EngineeringBudapest University of Technology and EconomicsMűegyetem rkp.3Budapest H-1111Hungary

Owing to the persisting hype in pushing toward global carbon neutrality,the study scope of atmospheric science is rapidly *** numerous trending topics,energy meteorology has been attracting the most attention *** essential skill of solar energy meteorologists is solar power curve modeling,which seeks to map irradiance and auxiliary weather variables to solar power,by statistical and/or physical *** this regard,this tutorial review aims to deliver a complete overview of those fundamental scientific and engineering principles pertaining to the solar power *** power curves can be modeled in two primary ways,one of regression and the other of model *** classes of modeling approaches,alongside their hybridization and probabilistic extensions,which allow accuracy improvement and uncertainty quantification,are scrutinized and contrasted thoroughly in this review.

关键词： review energy meteorology solar power curve model chain solar power prediction