检索结果-南通市图书馆

STRUCTURE OF Al-Cu EUTECTIC ALLOY SOLIDIFIED IN COMPLEX FIELD OF CENTRIFUGAL AND ELECTROMAGNETIC FORCES

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1997年第2期10卷 120-126页

作者： w.q. Zhang Y.F. Zhu Y.S. Yang and Z.q. Hu (State Key Lab. of RSA, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015,China) Inst of Metal Research Chinese Acad of Sciences Shenyang China

The effects of magnetic field on macro and microstructure of Al-CuAl2 eutectic alloy produced by electromagnetic centrifugal casting have been erperimentally investigated in the present paper. Electromagnetic stirring can lead to columnar formation in the cuter region and equiaxed in the inner, and otherwise cause the lamellae coarsened and the microstructure morphology to change from lamella to rod and then to block,if the electromagnetic stirring is intensified.

关键词： electromagnetic stirring centrifgal force Al-Cu eutectic alloy

Forced Convective Heat Transfer and Pressure Drop of Air Flowing in a Rectangle Duct with Cross-Ribs on the Opposite walls

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2002年第3期11卷 259-270页

作者： B.Deng T.T.wong w.q.tao School of Power and Energy Xi’an Jiaotong University Xi’an China Department of Mechanical Engineering The Hong Kong Polytechnic University Hong Kong

Experiments were conducted to investigate the forced convective heat transfer and flow friction of turbulent airflow in a rectangular duct with cross-ribs attached at the two principal walls in the Reynolds number range from 5000 to 40000. The effect of the rib cross angle (45° 60° 75° and the height (4 mm, 5 mm) of the cross-ribs on the forced convection and flow friction were tested. Non-dimensional correlations for the duct average Nusselt number and friction factor of cross-ribs duct were developed from the test data. Experiments were also conducted for the corresponding parallel ribs to compare their relative performance. The experimental results show that both of the convective heat transfer coefficient and friction factor were increased with cross-ribs, with 45°cross-ribs being the best. Compared with parallel ribs normal to the flow direction under identical flow rate and identical pumping power constraints, the cross-ribs can enhance heat transfer in the lower Reynolds number region, while

关键词： cross-ribs forced convection heat transfer enhancement.

PROPERTIES OF MgB_2 FILMS FABRICATED ON COPPER CATHODES BY ELECTROCHEMICAL TECHNIqUE

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2008年第5期21卷 351-354页

作者： H.Z. Yang X.G. Sun w.q. Huang M.L. Li X.M. Yu B.S. Zhang Y. qi q. Zhao Institute of Materials Physics and Chemistry School of Sciences Northeastern University Shenyang 110004 China Key Laboratory for Anisotropy and Texture of Materials Ministry of Education Northeastern University Shenyang 110004 China Department of Applied Physics School of Sciences Shenyang University of Technology Shenyang 110178 China

An electrochemical technique has been introduced and applied to fabricate superconducting MgB2 films in molten salts. MgCl2, Mg（BO2）2, NaCl, and KCl were used as electrolyte, graphite was used as the anode, and copper was used as the cathode, respectively. X-ray diffraction （XRD） analysis was chosen to investigate the phase composition and crystallinity of the films at different electrolysis temperatures. Stan- dard four-probe technique and SqUID were applied to investigate the temperature dependence of resistance （R-T） properties and magnetic properties of the films, respectively. The results indicate that MgB2 films have been fabricated on the copper cathodes, and superconducting transition takes place close to 50 K.

关键词： MgB2 film Electrochemistry Cu cathode

Acute and chronic excitotoxicity in ischemic stroke and late-onset Alzheimer's disease

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第7期20卷 1981-1988页

作者： Shan Ping Yu Emily Choi Michael qJiang Ling wei Department of Anesthesiology Emory University School of MedicineAtlantaGAUSA Center for Visual and Neurocognitive Rehabilitation Atlanta Veterans Affairs Medical CenterDecaturGAUSA

Stroke and Alzheimer's disease are common neurological disorders and often occur in the same *** comorbidity of the two neurological disorders represents a grave health threat to older *** review presents a brief background of the development of novel concepts and their clinical *** activity of glutamatergic N-methyl-D-aspartate receptors and N-methyl-D-aspartate receptor-mediated Ca^(2+)influx is critical for neuronal *** ischemic insult induces prompt and excessive glutamate release and drastic increases of intracellular Ca^(2+)mainly via N-methyl-D-aspartate receptors,particularly of those at the extrasynaptic *** Ca^(2+)-evoked neuronal cell death in the ischemic core is dominated by necrosis within a few hours and days known as acute ***,mild but sustained Ca^(2+)increases under neurodegenerative conditions such as in the distant penumbra of the ischemic brain and early stages of Alzheimer's disease are not immediately toxic,but gradually set off deteriorating Ca^(2+)-dependent signals and neuronal cell loss mostly because of activation of programmed cell death *** on the Ca^(2+)hypothesis of Alzheimer's disease and recent advances,this Ca^(2+)-activated“silent”degenerative excitotoxicity evolves from years to decades and is recognized as a unique slow and chronic *** N-methyl-D-aspartate receptor subunit GluN3A,primarily at the extrasynaptic site,serves as a gatekeeper for the N-methyl-D-aspartate receptor activity and is neuroprotective against both acute and chronic *** stroke and Alzheimer's disease,therefore,share an N-methyl-D-aspartate receptor-and Ca^(2+)-mediated mechanism,although with much different time *** is thus proposed that early interventions to control Ca^(2+)homeostasis at the preclinical stage are pivotal for individuals who are susceptible to sporadic late-onset Alzheimer's disease and Alzheimer's disease-related

关键词： Ca^(2+)hypothesis cognitive deficits hyperactivity late-onset Alzheimer's disease neurodegeneration N-methyl-D-aspartate receptors N-methyl-D-aspartate receptor subunits pathogenesis preventive treatment

Experimental Study on Transient Natural Convection in a Cube Enclosure with an Isolated Vertical Cyclically Heated Plate

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 1999年第1期8卷 51-58页

作者： C. M. Ling q. w. wang w. q. tao H. Ozoe School of Energy and Power Engineering Xi’an Jiaotong University Xi’an China Institute of Advanced Material Study Kyushu University 86 Kasuga Japan

The low frequency cyclical transient natural convection in a cube enclosure with an internal isolated vertical heated plate was investigated experimentally. A computer-aided experimental system was designed to generate the cyclical heating power input and also used for data reduction. The effects of the cyclic heating power input amplitude (from 0 to 8 w) and frequency (from 1/5400 s-1 to 1/600 s-1)as well as the per-cycle time-average power input (from 8 to 24 w) on the transient and time-average Nusselt number were parametrically studied. It was found that for such cyclical transient natural convection with low frequency, the plate heating power input amplitude and frequency have little effects on the time-average Nusselt number as long as the cyclical time-average heating power input remains the same, although the transient Nusselt number may be significantly affected. Therefore, the modified Grashof number based on the plate average heat flux can be used to characterize the time-average heat transfer process. The plate time-average Nusselt number is about 15% less than the infinite-space Nusselt number. The location of the isolated plate in enclosure does not appreciably influence the time-average heat transfer characteristics of the plate.

关键词： natural convection in enclosure isolated plate transient cyclically heating power input.

Localization of q-form fields on a de Sitter brane in chameleon gravity

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2024年第3期19卷 11-18页

作者： Yi Zhong tao-tao Sui School of Physics and Electronics Science Hunan UniversityChangsha 410082China Lanzhou Center for Theoretical Physics Key Laboratory of Theoretical Physics of Gansu Provinceand Key Laboratory of Quantum Theory and Applications of MoELanzhou UniversityLanzhou 730000China College of Physics Nanjing University of Aeronautics and AstronauticsNanjing 211106China

Recently,it was found that the vector field can be naturally localized on the thick brane in chameleon *** this work,we extend this study to encompass de Sitter brane *** focus on the localization of q-form *** scalar and vector fields can be localized on the de Sitter brane,while the KR field cannot be *** condition for localization of the scalar and vector fields is ***,we investigate the localization characteristics in two examples with given conformal factor b(ϕ).In the first case,the effective potentials and KK modes of the matter fields are obtained asymmetric even though the de Sitter brane has Z2 *** the second case,volcano-like effective potentials are generated in the de Sitter brane model.

关键词： brane q-form field chameleon gravity

Zinc Oxide-Based q-Switched Erbium-Doped Fiber Laser

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

Chinese Physics Letters 2017年第4期34卷 43-45页

作者： N.A.Aziz A.A.Latiff M.q.Lokman E.Hanafi S.w.Harun Department of Electrical Engineering Faculty of Engineering University of Malaya Kuala Lumpur 50603 Malaysia Photonics Research Centre University of Malaya Kuala Lumpur 50603 Malaysia

we demonstrate a q-switched erbium-doped fiber laser （EDFL） using a newly developed zinc oxide- （ZnO） based saturable absorber （SA）. The SA is fabricated by embedding a prepared ZnO powder into a poly（vinyl alcohol） film. A small piece of the film is then sandwiched between two fiber ferrules and is incorporated in an EDFL cavity for generating a stable q-switching pulse train. The EDFL operates at 1560.4nm with a pump power threshold of 11.8mw, a pulse repetition rate tunable from 22.79 to 61.43kHz, and the smallest pulse width of 7.00 μs. The q-switching pulse shows no spectral modulation with a peak-to-pedestal ratio of 62 dB indicating the high stability of the laser. These results show that the ZnO powder has a great potential to be used for pulsed laser applications.

关键词： Zinc Oxide-Based q-Switched Erbium-Doped Fiber Laser SA ZnO

Oxygen isotope characteristics of carbonate rocks as proxies for paleo-elevation in the qaidam Basin

在线全文

学校读者我要写书评

暂无评论

Oxygen isotope characteristics of carbonate rocks as proxies...

Topological phase transitions and Majorana zero modes induced by the periodic potential in an antiferromagnetic chain

第九届全国成矿理论与找矿方法学术讨论会

作者： Aiertiken A. SONG Hao Yan w.q. Chengdu University of Technology Key Laboratory of Uranium Geology China Geological Survey Key Laboratory of Nuclear Techniques in Geosciences of Sichuan Province

The restoration of paleo-topographic and geomorphic features is of great significance for indicating the regional geological evolution process and reconstructing the regional evolution history. Oxygen isotope in atmospheric precipitation show obvious fractionation with the change of altitude through observation of a large number of modern precipitation isotope characteristics and analysis of isotope fractionation theory (e.g., Rowley,

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2023年第8期75卷 156-162页

作者： K w Shen q Chen College of Physics and Mechanical&Electrical Engineering Jishou UniversityJishou 416000China School of Computational Science and Electronics Hunan Institute of EngineeringXiangtan 411104China

we investigate the topological properties of an antiferromagnetic(AFM)chain with an on-site periodic potential,considering the intrinsic spin–orbit coupling and an external Zeeman field along with the *** results indicate that Majorana zero modes(MZMs)can be observed by adjusting the strength of the periodic *** have calculated the energy spectrum,the wave-function and transport properties,and all these results support the existence of MZMs in the AFM ***,multiple topological phase transitions occur as the strength of the periodic potential changes,and several regions support MZMs.

关键词： AFM chain Majorana zero modes topological phase transitions periodic potential