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Thermo-Mechanical Calculation of Printed Circuit Heat Exchanger Using Homogenization

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Journal of Thermal Science 2022年第6期31卷 2309-2328页

作者： GARNIER Christophe VINCENT Sébastien LAMAGNERE Pierre LEJEAIL Yves CACHON Lionel CEA DESIRESNENuclear Technology DepartmentCadarache F-13108 Saint-Paul-Lez-DuranceFrance

The Finite-Element Method(FEM) is mainly used to design Compact Heat Exchanger structures. However, the narrow channel structures require fine mesh to accurately compute stress and strain. Combined with the dimensions of the overall component, this leads to an excessively large numerical model and therefore long computing time. This is especially true for transient thermal analyses, which require taking into account the full geometry. It is therefore interesting to reduce the size of the mesh. Periodic homogenization is an efficient method for achieving this goal. It can be applied to the core of the structure when periodic patterns(identified on basis of the arrangement of the channels) exist. A method based on this technique, with some improvements, is proposed in this paper for thermal loading without internal pressure. In addition to the Equivalent Homogenous Medium(EHM) replacing the periodic patterns, some explicit channels are interposed between the EHM and the cover plates. This has two advantages. The first is to smooth the transition of stiffness between the cover plates and the homogenized medium. The second one is to be able to directly compute stress and strain on the most critical channels located in this area. This paper assesses the method’s effectiveness for thermal loadings in order to conduct thermal stress analyses. First, the equivalent elastic constants of the EHM are obtained with a numerical Finite Elements Method. Then, two 2D cases using EHM are compared against a 2D explicit model(i.e. explicit geometry for the core channels). These cases are chosen to validate the EHM itself and its effectiveness for a real section of the heat exchanger. Results show very good agreement with a relative difference lower than 1%. In addition, the sensitivity to the number of layers added between the EHM and the cover plates is analysed. It is recommended interposing at least two layers of patterns to obtain converged results for the considered configuration

关键词： compact heat exchanger thermal stress finite element method homogenization

Bayesian inference of biomass growth characteristics for sugi(***)and hinoki(***)forests in self-thinned and managed stands

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Forest Ecosystems 2021年第4期8卷 1006-1023页

作者： Valerie Nicoulaud-Gouin Marc-Andre Gonze Pierre Hurtevent Phillippe Calmon Institut de Radioprotection et de Surete Nucleaire St Paul-Lez-DuranceFrance

Background:Forests are an important sink for atmospheric carbon and could release that carbon upon deforestation and *** stand biomass dynamic of evergreen forests has become necessary to improve current biomass production *** different growth processes of managed forests compared to self-managed forests imply an adaptation of biomass prediction ***:In this paper we model through three models the biomass growth of two tree species(Japanese cedar,Japanese cypress)at stand level whether they are managed or not(self-thinning).One of them is named self-thinned model which uses a specific self-thinning parameterαand adapted to self-managed forests and an other model is named thinned model adapted to managed *** latter is compared to a Mitscherlich *** self-thinned model takes into account the light competition between trees relying on easily observable parameters(*** density).A Bayesian inference was carried out to determine parameters values according to a large database ***:In managed forest,Bayesian inference results showed obviously a lack of identifiability of Mitscherlich model parameters and a strong evidence for the thinned model in comparison to Mitscherlich *** self-thinning forest,the results of Bayesian inference are in accordance with the self-thinning 3/2 rule(α=1.4).Structural dependence between stand density and stand yield in self-thinned model allows to qualifying the expression of biological time as a function of physical time and better qualify growth and mortality *** mortality rate is 2.5 times more important than relative growth rate after about 40 years *** density and stand yield can be expressed as function of biological time,showing that yield is independent of initial ***:This paper addressed stand biomass dynamic models of evergreen forests in order to improve biomass growth dynamic assessment at regional scale relying on easily observable

关键词： Dynamic Biomass Self-thinning Sugi Hinoki Competition-Density rule

Prototype Engineering Test Platform of ITER Magnet Gravity Support

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Plasma Science and Technology 2013年第2期15卷 192-195页

作者：廖敏李鹏远侯炳林杨淑娟付猷昆 R. GALLIX Southwestern Institute of Physics ITER Organizaion Cadarache 13108 St.Paul-Lez-Durance 610225 France

ITER magnet gravity support （GS） has been redesigned as a structure of pre- assembled nmlti-flexible plates instead of the original welded structure. In the past several years, engineering tests of the new structure have been proposed. A prototype engineering test plat- form is being developed. In order to apply the loads/load combinations onto the test mock-up, seven hydraulic bolt tensioners in three directions have been applied to simulate various loads （forces and moments）, through which the deformation of bolts, flexible plates and clamp blocks, the stress distribution in the flexible plates, the friction between the contact surface, etc. can be monitored/tested. The measurement and control system includes seven sets of synchronization controller, a 16-channel strain gauge, 25 sets of displacement sensors, etc. Principles of EDC220 digital controller and development of multi-channel control software are also demonstrated.

关键词： ITER gravity support engineering test FEM analysis measurement andcontrol system

Gyrokinetic simulation of low-n Alfvénic modes in tokamak HL-2A plasmas

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Chinese Physics B 2023年第2期32卷 358-365页

作者：林文浩李继全 J Garcia S Mazzi Southwestern Institute of Physics Chengdu 610041China CEA IRFM13108Saint-Paul-lez-DuranceFrance EPFL Swiss Plasma CenterLausanneSwitzerland

The turbulence characteristics of plasmas with internal transport barriers in the HL-2A tokamak are analyzed by means of linear gyrokinetic simulations. It is found that turbulence is dominated by the ion temperature gradient(ITG)mode together with large-scale modes characterized by high-frequency electromagnetic fluctuation, which are destabilized by the steep ion temperature gradient in the weak magnetic shear regime. Comparison with solutions of analytical dispersion relations shows that their linear features match well with the beta-induced Alfvén eigenmode branch of the shear Alfvénic spectrum. It is further clarified that the large population of fast ions in these plasmas plays a stabilization role through the dilution mechanism in high-n ITG mode regimes.

关键词： low-n Alfvénic modes fast ions gyrokinetic simulation tokamak

Gastrointestinal disorders associated with migraine: A comprehensive review

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World Journal of Gastroenterology 2016年第36期22卷 8149-8160页

作者： Carlos R Cámara-Lemarroy Rene Rodriguez-Gutierrez Roberto Monreal-Robles Alejandro Marfil-Rivera Servicio de Neurología Hospital Universitario "Dr. José E. González" Universidad Autónoma de Nuevo León Servicio de Endocrinología Hospital Universitario "Dr. José E. González" Universidad Autónoma de Nuevo León Servicio de Gastroenterología Hospital Universitario "Dr. José E. González" Universidad Autónoma de Nuevo León

Migraine is a recurrent and commonly disabling primary headache disorder that affects over 17% of women and 5%-8% of men. Migraine susceptibility is multifactorial with genetic, hormonal and environmental factors all playing an important role. The physiopathology of migraine is complex and still not fully understood. Many different neuropeptides, neurotransmitters and brain pathways have been implicated. In connection with the myriad mechanisms and pathways implicated in migraine, a variety of multisystemic comorbidities(e.g., cardiovascular, psychiatric and other neurological conditions) have been found to be closely associated with migraine. Recent reports demonstrate an increased frequency of gastrointestinal(GI) disorders in patients with migraine compared with the general population. Helicobacter pylori infection, irritable bowel syndrome, gastroparesis, hepatobiliary disorders, celiac disease and alterations in the microbiota have been linked to the occurrence of migraine. Several mechanisms involving the gut-brain axis, such as a chronic inflammatory response with inflammatory and vasoactive mediators passing to the circulatory system, intestinal microbiota modulation of the enteric immunological milieu and dysfunction of the autonomic and enteric nervous system, have been postulated to explain these associations. However, the precise mechanisms and pathways related to the gut-brain axis in migraine need to be fully elucidated. In this review, we survey the available literature linking migraine with GI disorders. We discuss the possible physiopathological mechanisms, and clinical implications as well as several future areas of interest for research.

关键词： Migraine Headache Microbiota Review Gastrointestinal diseases

Static Structural Analysis for a Neutron Shielding Block in ITER

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Plasma Science and Technology 2013年第2期15卷 142-147页

作者：郝俊川宋云涛王晓宇 K.IOKI 杜双松戢翔冯昌乐徐扬 Institute of the Plasma Physics Chineses Academy of Science ITER Organization 13108 St. Paul lez Durance France School of Mechanical Engineering Anhui University of Science and Technology

The ITER neutron shielding blocks are located between the outer shell and the inner shell of the vacuum vessel to provide neutron shielding. Considering the combined loads acting on the shielding blocks during ITER plasma operation, the structure of the shielding blocks must be evaluated. Using the finite element method with ANSYS analysis software, static structural analysis is performed, including elastic analysis and limit analysis for one typical shielding block. The evaluated results based on RCC-MR code show that the structure of this shielding block can meet the design requirement.

关键词： vacuum vessel neutron shielding block finite element RCC-MR elastic analysis limit analysis

Design of Tokamak ELM Coil Support in High Nuclear Heat Environment

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Plasma Science and Technology 2014年第3期16卷 300-304页

作者：张善文宋云涛王忠伟戢翔 E.DALY M.KALISH 卢速杜双松刘旭峰冯昌乐杨洪王松可 Institute of Plasma Physics Chinese Academy of Sciences ITER Organization Route de Vinonsur Verdon13115 Saint Paul-lez-DuranceFrance Princeton Plasma Physics Laboratory

In Tokomak, the support of the ELM coil, which is close to the plasma and subject to high radiation level, high temperature and high magnetic field, is used to transport and bear the thermal load due to thermal expansion and the alternating electromagnetic force generated by high magnetic field and AC current in the coil. According to the feature of ITER ELM coil, the mechanical performance of rigid and flexible supports under different high nuclear heat levels is studied. Results show that flexible supports have more excellent performance in high nuclear heat condition than rigid supports. Concerning thermal and electromagnetic （EM） loads, optimized results further prove that flexible supports have better mechanical performance than rigid ones. Through these studies, reasonable support design can be provided for the ELM coils or similar coils in Tokamak based on the nuclear heat level.

关键词： tokomak ELM coil rigid support flexible support high nuclear heat

STUDY OF THREE-DIMENSIONAL SEPARATION OF BOUNDARY LAYER OVER BLUNT BODIES

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Journal of Hydrodynamics 2009年第1期21卷 100-107页

作者： ATMANI R. BRIMA A. ASKOVIC R. Laboratoire de mécanique des fluides Université de ValenciennesAulnoy lez Valenciennes 59326 France Département de Mécanique Université de BiskraBiskra 07000 Algérie

In the case of three-dimensional flows, the separation can be defined in more than one way. Discussions about three-dimensional boundary layer separation in the literature have found a rational extension of the zero skin friction. Attempts have been made to establish the identity of “separation lines”. Among definitions, these may be found：（1） envelopes of limiting streamlines, （2） lines dividing flow which has come from different regions, （3） lines of singularities （problems of topology）, （4） lines on which some component of the skin friction vanishes. Each of these is valid under certain conditions, but none is universally valid. In the present work, we use the definition （4）, i.e. at low incidence of a blunt body the separation line is identified as the zero of the meridian skin friction component （Wang 1975）. So the separation line on a flattened spheroid （6：3：1） at 6° of incidence is calculated, as well as experimentally determined by using the electrochemical method, which allows to follow the evolution of the parietal velocity gradient.

关键词： three-dimensional flows separation boundary layers blunt bodies

COVID-19 and neurologic manifestations:a synthesis from the child neurologist’s corner

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World Journal of Pediatrics 2022年第6期18卷 373-382页

作者： Carolina Valderas Gastón Méndez Alejandra Echeverría Nelson Suarez Katherin Julio Francisca Sandoval Department of Neurology Hospital Dr.Exequiel González CortésGran Avenida JoséMiguel Carrera 33008900085SantiagoRegión MetropolitanaChile

Background Since December 2019,the SARS-CoV-2 virus has been a global health *** main clinical presentation of this virus is a flu-like disease;however,patients with diverse neurologic manifestations have also been *** this review,we attempt to summarize,discuss and update the knowledge of the neurologic manifestations in the pediatric population affected by SARS-CoV-2 infection and the pandemic’s effects in children with neurologic *** sources This review analyzes studies found on the PubMed database using the following keywords:Neurologic manifestations COVID-19,Neurological COVID-19,coronavirus,SARS-CoV-2,pediatric COVID-19,COVID-19 in children,MIS-C,Pediatric Inflammatory Multisystem Syndrome,Guillain BarréSyndrome,Stroke,ADEM,and Anti-NMDA *** studies cited were published between 2004 and 2022,and represent the most relevant articles in the *** World Health Organization COVID-19 online dashboard was assessed to obtain updated epidemiological *** The most common neurologic symptoms in the pediatric population are headache,seizures,encephalopathy,and muscle *** can be present during COVID-19 or weeks after recovering from *** who presented with multi-system inflammatory syndrome had a higher incidence of neurologic manifestations,which conferred a greater risk of morbidity and *** neuro-pathophysiological mechanisms have been proposed,including direct virus invasion,hyper-inflammatory reactions,multi-systemic failure,prothrombotic states,and immune-mediated *** the other hand,the COVID-19 pandemic has affected patients with neurologic diseases,making it challenging to access controls,treatment,and *** Various neurologic manifestations have been associated with children’s SARS-CoV-2 *** is important to identify and give them proper and opportune treatment because they can be potentially grave and life-threatening;some can lead to long-lasting se

关键词： Coronavirus COVID-19 Neurologic Pediatric SARS-CoV-2 MIS-C