检索结果-南通市图书馆

A Mathematical Model for the heat Radiation Characteristics of Materials

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2004年第1期13卷 75-79页

作者： D. h. xia Y. h. wu Univ Sci & Technol Beijing Dept Thermal Engn Beijing 100083 Peoples R China

Based on the model of harmonic oscillators, a mathematical model for the heat radiation characteristics of materials such as semiconductors, metals, plasmas and ionic crystals is established in this paper. The main factors affecting the heat radiation characteristics of materials are also analyzed at length. The emissivity is calculated for revealing the mechanism of emitting, absorbing, transmitting and reflecting the heat radiation wave.

关键词： harmonic oscillator mathematical Model heat radiation wave emissivity.

Spray granulation of Fe and C nanoparticles and their impedance match for microwave absorption

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第3期34卷 496-502页

作者： h.huang Y.Gao C.F.Fang A.M.wu x.L.Dong B.S.Kim J.h.Byun G.F.Zhang D.Y.Zhou Key Laboratory of Materials Modification by Laser Ionand Electron Beams(Ministry of Education)School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Composites Research Division Korea Institute of Materials Science797 Changwon-daeroSeongsan-guChangwonGyeongnam642-831Republic of Korea

The microwave absorbents of Fe and C nanoparticles as magnetic loss and dielectric loss material respectively were composited with the polyvinyl alcohol （PVA） as binder by spray granulation method, The electromagnetic parameters of Fe and C composite particles were analyzed by vector network. The complex permittivity and magnetic permeability of Fe and C composite particles matched well with increasing C nanoparticle content, and then the microwave loss property was improved. A minimum reflection loss （RL） of -42.7 dB at 3.68 Ghz for a composite with 4.6 mm in thickness can be obtained when the content ratio of the C nanoparticles, the modified Fe nanoparticles and the PVA is 21：49：30 （Sample 3）.

关键词： Dielectric loss Magnetic loss Spray granulation method Impedance match

Convexification of hybrid AC-DC Optimal Power Flow with Line-Commutated Converters

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2024年第2期10卷 617-628页

作者： hongyuan Liang Zhigang Li J.h.Zheng Q.h.wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

Line-commutated converter (LCC)-based high-voltage DC (hVDC) systems have been integrated with bulk AC power grids for interregional transmission of renewable power. The nonlinear LCC model brings additional nonconvexity to optimal power flow (OPF) of hybrid AC-DC power grids. A convexification method for the LCC station model could address such nonconvexity but has rarely been discussed. We devise an equivalent reformulation for classical LCC station models that facilitates second-order cone convex relaxation for the OPF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with its proof. Equivalence of the proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally optimal solution of the original OPF can be efficiently obtained from relaxed model.

关键词： AC-DC power system convex relaxation linecommutated converter optimal power flow second-order cone programming

Dispatchable Region for Active Distribution Networks Using Approximate Second-order Cone Relaxation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2023年第6期9卷 1999-2007页

作者： Zhigang Li Wenjing huang J.h.Zheng Q.h.wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China

Uncertainty in distributed renewable generation threatens the security of power distribution *** concept of dispatchable region is developed to assess the ability of power systems to accommodate renewable generation at a given operating *** DC and linearized AC power flow equations are typically used to model dispatchable regions for transmission systems,these equations are rarely suitable for distribution *** achieve a suitable trade-off between accuracy and efficiency,this paper proposes a dispatchable region formulation for distribution networks using tight convex *** cone relaxation is adopted to reformulate AC power flow equations,which are then approximated by a polyhedron to improve ***,an efficient adaptive constraint generation algorithm is employed to construct the proposed dispatchable *** studies on distribution systems of various scales validate the computational efficiency and accuracy of the proposed method.

关键词： Dispatchable region distribution system renewable power generation second-order cone relaxation uncertainty

NUMERICAL SIMULATION OF MOLTEN POOL AND CONTROL STRATEGY OF KISS POINT IN A TWIN-ROLL STRIP CASTING PROCESS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2008年第6期21卷 459-468页

作者： G.M. Cao C.G. Li Z. Y. Liu D. wu G.D. Wang x.h. Liu State Key Laboratory of Rolling ＆ Automation Northeastern University Shenyang 110004 China

Coupled turbulent flow, temperature fields of the twin-roll casting strip process were simulated by three-dimensional finite element method. Based on the heat balance calculation and using inverse methods between the simulations and real experiments, the relational models among casting speed, location, and coefficient of heat transfer between molten metal and rolls in different regions are given. In the simulation, the calculated surface temperatures are in good agreement with the measured values. An on-line model of kiss point is derived by simulations and the geometry of molten pool, corresponding control strategy is also proposed.

关键词： Twin-roll strip casting Coupled temperature and flow field Numerical simulation Kiss point Control strategy

The ESCRT protein ChMP5 escorts αβ T cells through positive selection

在线全文

学校读者我要写书评

暂无评论

Cellular & Molecular Immunology 2018年第7期15卷 654-656页

作者： Glendon S wu Craig h Bassing Immunology Graduate Group Perelman School of Medicine at the University of PennsylvaniaPhiladelphiaPA 19104USA Divsion of Cancer Pathobiology Department of Pathology and Laboratory MedicineChildren’s Hospital of PhiladelphiaAbramson Family Cancer Research InstitutePerelman School of Medicine at the University of PennsylvaniaPhiladelphiaPA 19104USA

αβ T lymphocytes are critical for host protection against pathogens and are notable for their recent use as immunotherapeutic agents for the treatment of human ***,their dysfunction is associated with a variety of disease states,including autoimmune and immunodeficient syndromes that frequently result from improper αβT cell development in the *** thymic egress,mature αβ T cells are activated when their surface T-cell receptor(TCR)engages peptide antigens displayed by major histocompatibility complex(MhC)proteins expressed on antigenpresenting *** the thymus,each developing αβ T cell(thymocyte)recombines its TCRβ and TCRαgenes in an attempt to assemble and express a unique functional αβ TCR。

关键词： lymphocytes autoimmune combine

Flip the switch: BTG2–PRMT1 protein complexes antagonize pre-B-cell proliferation to promote B-cell development

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Cellular & Molecular Immunology 2018年第9期15卷 808-811页

作者： Glendon S wu Craig h Bassing Immunology Graduate Group Children’s Hospital of PhiladelphiaPerelman School of Medicine at the University of PennsylvaniaPhiladelphiaPA 19104USA Divsion of Cancer Pathobiology Department of Pathology and Laboratory MedicineChildren’s Hospital of PhiladelphiaAbramson Family Cancer Research InstitutePerelman School of Medicine at the University of PennsylvaniaPhiladelphiaPA 19104USA

B lymphocytes are vital components of vertebrate adaptive immune ***,B-cell dysfunction can promote autoimmunity and immunodefi-ciency,and errors in development can cause B-lineage lymphoid malignancies.B-cell development requires RAG1/RAG2(RAG)endonuclease-mediated assembly of immunoglobulin(Ig)*** assembly of Ig heavy chain(Igh)genes in G1-phase pro-B cells produces Igh proteins that pair with VpreB/λ5 to form pre-B-cell receptor(pre-BCR)*** pro-B cells,pre-BCR signaling inhibits Rag1/Rag2 transcription,stabilizes Cyclin D3 to drive cellular proliferation and promotes differentiation of large pre-B cells.

关键词： lymphocytes lymphoid complexes

Coherent Acoustic Phonon and Its Chirping in Dirac Semimetal Cd_3As_2

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 2018年第11期35卷 56-60页

作者： Fei Sun M.Yang M W Yang Q.wu h.Zhao x.Ye Youguo Shi Jimin Zhao Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190 School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049

Ultrafast optical spectroscopy of a single crystal of a Dirac semimetal Cd_3As_（2 ）is carried *** acoustic phonon（AP）mode with central frequency f=0.037 Thz（i.e.,1.23 cm^（-1）or 0.153 meV）is unambiguously generated and detected,which we attribute to laser-induced thermal *** AP chirping（i.e.,variation of the phonon frequency）is clearly detected,which is ascribed to heat capacity variation with *** comparing our experimental results and the theoretical model,we obtain a chirping time constant,which is 31.2 ps at 6 K and 19.8 ps at 300 K,***,we identify an asymmetry in the AP frequency domain peak and find that it is caused by the chirping,instead of a Fano ***,we experimentally demonstrate that the central frequency of AP is extremely stable with varying laser fluence,as well as temperature,which endows Cd_3As_2application potentials in thermoelectric devices.

关键词： As Cd AP Coherent Acoustic Phonon and Its Chirping in Dirac Semimetal Cd3As2

Rapid drop in ductility of the bimodal-structured Mg-15Gd binary alloy during early aging

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第9期12卷 3772-3779页

作者： R.G.Li S.Q.Zhou h.Zhang R.Z.wu D.wu J.R.Li B.S.Liu S.S.Li x.Li B.J.Wang School of Mechanical and Power Engineering Shenyang University of Chemical TechnologyShenyang 110142China Key Laboratory of Superlight Materials&Surface Technology Ministry of EducationHarbin Engineering UniversityHarbin 150001China Shenyang Key Laboratory for the Utilization Technology of Magnesium and Calcium Resources Shenyang University of Chemical TechnologyShenyang 110142China School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang 110159China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Sciences62 Wencui RoadShenyang 110016China

A bimodal-structured Mg^(-1)5Gd binary alloy with 45%volume fraction of elongated grains and 55%of dynamically recrystallized(DRxed)grains is fabricated by the extrusion *** precipitating behavior correlating with the evolution of mechanical properties is systematically characterized during the subsequent aging treatment at 200°*** extruded alloy presents an outstanding strength with tensile yield strength of 466 MPa and ultimate tensile strength of 500 MPa at peak aging condition,while the elongation drops from 9.2%in extrusion state to 3.1%.It is found there obviously exist a rapidly decreasing range of ductility at the early stage of *** during this time,the nano precipitates form preferentially at lamellar dislocation boundaries(LDBs)within the elongated grains,but there is no dense and uniform precipitation in the *** results suggest that the low elongation in the aged Mg^(-1)5Gd alloy is mainly attributed to the nano precipitates prior formed at the LDBs with a high density in the elongated *** related mechanism has been clarified.

关键词： Mg-Gd alloy Bimodal structure Segregation Precipitate Dislocation Boundary