检索结果-南通市图书馆

Gust response of an elasto-flexible morphing wing using fluid–structure interaction simulations

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第2期37卷 45-57页

作者： Jonathan PFLÜGER christian breitsamter Department of Mechanical Engineering Technical University of MunichGarching 85748Germany

Small and micro unmanned aircraft are the focus of scientific interest due to their wide range of *** often operate in a highly unstable flight environment where the application of new morphing wing technologies offers the opportunity to improve flight *** investigated concept comprises port and starboard adjustable wings,and an adaptive elastoflexible membrane serves as the lifting *** focus is on the benefits of the deforming membrane during the impact of a one-minus-cosine type *** a low Reynolds number of Re=264000,the morphing wing model is investigated numerically by unsteady fluid-structure interaction ***,the numerical results are validated by experimental data from force and moment,flow field,and deformation ***,with the rigid wing as the baseline,the flexible case is investigated,focusing on the advantages of the elastic *** all configurations studied,the maximum amplitude of the lift coefficient under gust load shows good agreement between the experimental and numerical *** the decay of the gust,they differ more the higher the aspect ratio of the *** considering the flow field,the main differences are due to the separation behavior on the upper side of the *** flow reattaches earlier in the experiments than in the simulations,which explains the higher lift values observed in the *** at one intermediate configuration does the lift amplitude of the rigid configuration exceeds that of the flexible by about 12%,with the elastic membrane resulting in a smaller and more uniform peak load,which is also evident in the wing loading and hence in the root bending moment.

关键词： Membrane wing Morphing wing Flexible wing surface Computational fluid dynam-ics Fluid-structure interaction Unsteady inflow condition Gust response

Flow-structure interaction of an inverted flag in a water tunnel

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2019年第12期62卷 57-67页

作者： YaoWei Hu JiangSheng Wang JinJun Wang christian breitsamter Key Laboratory of Fluid Mechanics(Beihang University) Ministry of EducationBeijing 100191China Lehrstuhl fur Aerodynamik und Stromungsmechanik Technische Universitat MiinchenGarching 85748Germany

Herein, the dynamics and flow fields of an inverted flag are studied using hydrogen bubble flow visualization and particle image velocimetry technologies at different height-to-length ratios and flow velocities in a water tunnel. Results show that the heightto-length ratio of the inverted flag at which the critical flow velocity remains nearly constant is approximately 1.4. Moreover, a nonperiodic flapping phenomenon is observed under various height-to-length ratios. This phenomenon may be attributed to the existence of multiple equilibrium solutions to the self-excited vibration system, thus engendering chaos in the system comprising an inverted flag and surrounding fluid. Other indications that the system has entered chaos include multiple frequencies, nonoverlapping phase diagram, and positive Lyapunov exponent. Further discussion of the flow fields around the inverted flag reveals that the large-amplitude oscillation is due to the flow separation, while the flapping instability is a static divergence instability. In the large flapping mode, the starting leading-edge vortex(LEV) is wrapped by Kelvin-Helmholtz instabilities,which are arranged at almost uniform spacing along a circular path. In addition, the variation in position, circulation, and radius of the starting LEV are discussed in detail.

关键词： inverted flag modes aperiodic flapping LEV

基于SCI／ERA方法的高效气动力降阶模型

在线全文

学校读者我要写书评

暂无评论

计算力学学报 2012年第1期29卷 19-24页

作者：窦怡彬徐敏 christian breitsamter 西北工业大学航天学院西安710072 慕尼黑工业大学空气动力学研究所慕尼黑85748

由正交Walsh函数构造Walsh-单信号-复合-输入,对其作用下的计算流体力学响应采用单信号-复合-输入/特征系统实现算法SCI/ERA(Single-Composite-Input/Eigensystem Realization Algorithm)辨识得到离散时间非定常气动力状态空间降阶模型... 详细信息

由正交Walsh函数构造Walsh-单信号-复合-输入,对其作用下的计算流体力学响应采用单信号-复合-输入/特征系统实现算法SCI/ERA(Single-Composite-Input/Eigensystem Realization Algorithm)辨识得到离散时间非定常气动力状态空间降阶模型。通过对Isogai机翼剖面气动弹性算例的计算证明该方法具有和非定常计算流体力学方法相当的精度同时模型维数降低2个数量级;在模型构造时间上,SCI/ERA方法比脉冲/ERA方法计算效率提高24%,同时内存占用减小34%;由理论分析可知当耦合结构模态数目增加时,SCI/ERA方法所需的计算开销增幅远小于脉冲/ERA方法;采用频域平衡特征正交分解BPOD(Balanced Proper Orthogonal Decomposition)方法可以准确地从降阶模型中提取出一个低频二次降阶模型,同时保持与原模型相当的精度。二次降阶后模型维数进一步减小88%。

关键词：降阶模型单信号-复合-输入/特征系统实现算法平衡特征正交分解二次降阶

Cellular models of stress resistance may pave ways to fight neurodegenerative diseases

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第9期20卷 2579-2580页

作者： Thu Nguyen Minh Pham christian Behl Institute of Pathobiochemistry University Medical Center of the Johannes Gutenberg UniversityMainzGermany

Alzheimer's disease(AD),the most common form of neurodegeneration,is characterized by selective neuronal vulnerability and brain regionselective neuron *** entorhinal cortex and hippoc,ampal CA1 projection neurons are at greater risk in AD whereas other regions display resistance to ***,the cerebellum,a phylogenetically very old region,is affected only very late in the disease progression.

关键词： cortex resistance Alzheimer

Many faces of neuronal activity manipulation in Drosophila

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第9期20卷 2574-2576页

作者： Amber Krebs Steffen Kautzmann christian Klämbt Institut für Neuro-und Verhaltensbiologie MünsterGermany

Animals exhibit complex responses to external and internal *** information is computed by interconnected neurons that express numerous ion channels,which modulate the neuronal membrane *** can neuronal activity orchestrate complex motor patterns or allow learning from previous experience?To answer such questions,we need the ability not only to record,but also to modulate neuronal activity in both space(e.g.,neuronal subsets)and time.

关键词： manipulation potential. neuronal

Complement-dependent neuroinflammation in spinal cord injury:from pathology to therapeutic implications

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第5期20卷 1324-1335页

作者： Hassan Saad Bachar El Baba Ali Tfaily Firas Kobeissy Juanmarco Gutierrez Gonzalez Daniel Refai Gerald R.Rodts christian Mustroph David Gimbel Jonathan Grossberg Daniel L.Barrow Matthew F.Gary Ali M.Alawieh Department of Neurosurgery Emory University School of MedicineAtlantaGAUSA Department of Neurology Yale UniversityNew HavenCTUSA Center for Neurotrauma Multiomics&Biomarkers(CNMB)Morehouse School of MedicineAtlantaGAUSA

Spinal cord injury remains a major cause of disability in young adults,and beyond acute decompression and rehabilitation,there are no pharmacological treatments to limit the progression of injury and optimize recovery in this *** the thorough investigation of the complement system in triggering and propagating cerebral neuroinflammation,a similar role for complement in spinal neuroinflammation is a focus of ongoing *** this work,we survey the current literature investigating the role of complement in spinal cord injury including the sources of complement proteins,triggers of complement activation,and role of effector functions in the *** study relevant data demonstrating the different triggers of complement activation after spinal cord injury including direct binding to cellular debris,and or activation via antibody binding to damage-associated molecular *** effector functions of complement have been implicated in spinal cord injury,and we critically evaluate recent studies on the dual role of complement anaphylatoxins in spinal cord injury while emphasizing the lack of pathophysiological understanding of the role of opsonins in spinal cord *** this pathophysiological review,we systematically review the different translational approaches used in preclinical models of spinal cord injury and discuss the challenges for future translation into human *** review emphasizes the need for future studies to dissect the roles of different complement pathways in the pathology of spinal cord injury,to evaluate the phases of involvement of opsonins and anaphylatoxins,and to study the role of complement in white matter degeneration and regeneration using translational strategies to supplement genetic models.

关键词： complement neuroinflammation neuroplasticity regeneration spinal cord injury targeted therapy

Schrodinger and Klein-Gordon theories of black holes from the quantization of the Oppenheimer and Snyder gravitational collapse

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2023年第9期75卷 122-135页

作者： christian Corda SUNY Polytechnic Institute 13502 UticaNew YorkUSAIstituto Livi59100 PratoTuscanyItaly and International Institute for Applicable Mathematics and Information SciencesB M Birla Science CentreAdarshnagarHyderabad 500063India

The Schrodinger equation of the Schwarzschild black hole(BH) has been recently derived by the author and collaborators. The BH is composed of a particle, the 'electron', interacting with a central field, the 'nucleus'. Via de Broglie's hypothesis, one interprets the 'electron' in terms of BH horizon's modes. Quantum gravity effects modify the BH semi-classical structure at the Schwarzschild scale rather than at the Planck scale. The analogy between this BH Schrodinger equation and the Schrodinger equation of the s states of the hydrogen atom permits us to solve the same equation. The quantum gravitational quantities analogous of the fine structure constant and of the Rydberg constant are not constants, but the dynamical quantities have well-defined discrete spectra. The spectrum of the 'gravitational fine structure constant' is the set of non-zero natural numbers. Therefore, BHs are well-defined quantum gravitational systems obeying Schrodinger's theory: the 'gravitational hydrogen atoms'. By identifying the potential energy in the BH Schrodinger equation as being the gravitational energy of a spherically symmetric shell, a different nature of the quantum BH seems to surface. BHs are self-interacting, highly excited,spherically symmetric, massive quantum shells generated by matter condensing on the apparent horizon, concretely realizing the membrane paradigm. The quantum BH described as a'gravitational hydrogen atom' is a fictitious mathematical representation of the real, quantum BH, a quantum massive shell having a radius equal to the oscillating gravitational *** consequences emerge from this result:(i) BHs have neither horizons nor singularities;(ii) there is neither information loss in BH evaporation, nor BH complementarity, nor firewall paradox. These results are consistent with previous ones by Hawking, Vaz, Mitra and ***, the special relativistic corrections to the BH Schrodinger equation give the BH Klein–Gordon equation and the cor

关键词： quantum black holes information paradox quantum shells quantum levels Schrodinger and Klein-Gordon theories

Insensitive high explosives:Ⅳ. Nitroguanidine-Initiation & detonation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2019年第4期15卷 467-487页

作者： Ernst-christian Koch Lutradyn-Energetic Materials

This paper reviews the detonative properties of low bulk density(LBD),high bulk density(HBD)Nitroguanidine(NGu)(1),CAS-No:[556-88-7]and 82 explosive formulations based on NGu reported in the public *** rank the performance of those formulations they are compared with 15 reference compositions containing both standard high explosives such as octogen(HMX)(2),hexogen(RDX)(3),pentaerythritol tetranitrate(PETN)(4),2,4,6-trinitrotoluene(TNT)(5)as well as insensitive high explosives such as 3-nitro-1,2,4-triazolone(NTO)(6),1,3,5-triamino-2,4,6-trinitrobenzene(TATB)(7),1,1-diamino-2,2-dinitroethylene(FOX-7)(8)and N-Guanylurea dinitramide(FOX 12)(9).NGu based formulations are superior to those based on FOX-12 or TATB and are a close match with FOX-7 based explosives,the latter just having higher Gurney Energies(-10%)and slightly higher detonation pressure(+2%).NGu based explosives even reach up to 78% of the detonation pressure,82% Gurney energy and up to 95% of detonation velocity of ***-NGu dissolves in many melt cast eutectics forming dense charges thereby eliminating the need for costly High Bulk Density *** based formulations are at the rock bottom of sensitiveness among all the above-mentioned explosives which contributes to the safety of these *** review gives 132 references to the public *** a review on the synthesis spectroscopy and sensitiveness of Nitroguanidine see Ref.[1].

关键词： Cook-off Detonation Insensitive munitions Nitroguanidine Shock sensitvity

Special materials in pyrotechnics Ⅶ: Pyrotechnics used in thermal batteries

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2019年第3期15卷 254-263页

作者： Ernst-christian Koch Lutradyn Energetic Materials Science & Technology

Thermal batteries are unique direct current(DC) electrical power sources with long shelf live, high reliability and higher power density than classical alkaline batteries. This paper gives a brief overview into the working principle of thermal batteries and reviews the properties of zirconium/barium chromate(Zr/BaCrO4) pyrolant previously used as first fire and iron/potassium perchlorate(Fe/KClO4) pyrolant(Heat), commonly applied as heating pellet in thermal batteries and its hazard properties. The review gives 64 references to the public domain. CAS-Nos. Zr: [7440-67-7], BaCrO4: [10294-40-3], Fe: [7439-89-6], KClO4: [7778-74-7], Viton: [9011-17-0].CAS-Nos. Zr: [7440-67-7], BaCrO4: [10294-40-3], Fe: [7439-89-6], KClO4: [7778-74-7], Viton: [9011-17-0].

关键词： Barium chromate Heat-powder Iron Lithium Molten salt Potassium perchlorate Pyrotechnics Thermal battery Zirconium