用于三相并网逆变器稳定性分析的自导纳和伴随导纳建模

并网逆变器的稳定性分析通常采用导纳或阻抗的分析方法。不同于现有的序阻抗和序耦合的描述方法,采用复变量的表示方法将正负序变量统一,分析基于锁相环的三相并网逆变器的单频率输入双频率输出现象的产生机理,建立统一的并网逆变器的自导纳和伴随导纳模型,并对所建立的模型进行仿真和实验验证。依据Nyquist判据,分析自导纳和伴随导纳对并网逆变器稳定性的影响。实验结果表明,所建立的自导纳和伴随导纳模型可以获得更加准确的并网逆变器稳定性分析结果。

Room Temperature Magnetic Behavior of Sol-Gel Synthesized Mn Doped ZnO

Mn doped ZnO nano-crystallites were synthesized by state of the art sol-gel derived auto- combustion technique. As-burnt powder was investigated with different characterization techniques to explore the properties of Mn doped ZnO dilute magnetic semiconductor. X- ray diffraction measurements indicate that Mn doped ZnO retain wurtzite type hexagonal crystal structure like ZnO. Compositional and morphological studies were carried out by energy dispersive X-ray analysis and scanning electron microscopy, respectively. Temperature dependent resistivity of the sample exhibited the semiconducting behavior of the DMS material. Room temperature magnetic properties determined by vibrating sample magnetometer, revealed the presence of ferromagnetic and diamagnetic contributions in Mn doped ZnO.

Tunneling Conductance in a Normal Metal/Ferromagnetic Superconductor Nano-Junction at a Finite Temperature

In this study, we investigate the tunneling conductance at a finite temperature in a normal metal/ferromagnetic superconductor nano-junction where the ferromagnetic superconductor （FS） is in three different cooper pairing states： spin singlet s-wave pairing （SWP）, spin triplet opposite spin pairing （OSP）, and spin triplet equal spin pairing （ESP） while including Fermi wave mismatch （FWM） and effective mass mismatch （EMM） in two sides of the nano-junction. We find that the conductance shows clearly different behaviors all depending on the symmetries of cooper pairing in a manner that the conductance spectra shows a gap-like structure, two interior dips structure and zero bias peak for SWP, OSP, and ESP, respectively. Also, the effective FS gap （Δeff） is a linear and decreasing function of exchange field. The slope of （Δeff） versus exchange field for OSP is twice the SWP. Thus, we can determine the spin polarization of N/FS nano-junction based on the dependence of （Δeff） to exchange field.

Application and Self-assembly of Semiconductor Nanowire

The unique properties of semiconductor nanowires are introduced,and recent research progresses in application,self-assembly synthesis methods and mechanisms are summarized.

From Proton Conductive Nanowires to Nanofuel Cells： A Powerful Candidate for Generating Electricity for Self-Powered Nanosystems

The likely goal of nanotectulology is the integration of individual nanodevices into a nanosystem, which includes the nanodevice（s）, power harvesting unit, data processing logic system, and possibly wireless communication unit. A nanosystem requires a nanoscale power source to make the entire package extremely small and high performance. The nanofuel and nanobiofuel cells developed here represent a new self-powering approach in nanotechnology, and their power output is high enough to drive nanodevices for performing self-powered sensing. This study shows the feasibility of building self-powered nanosystems for biological sciences, environmental monitoring, defense technology and even personal electronics.

Spin-resolved self-doping tunes the intrinsic halfmetallicity of AIN nanoribbons

We present a first-principles theoretical study of electric field- and straincontrolled intrinsic half-metallic properties of zigzagged aluminium nitride （A1N） nanoribbons. We show that the half-metallic property of AIN ribbons can undergo a transition into fully-metallic or semiconducting behavior with application of an electric field or uniaxial strain. An external transverse electric field induces a full charge screening that renders the material semiconducting. In contrast, as uniaxial strain varies from compressive to tensile, a spin-resolved selective self-doping increases the half-metallic character of the ribbons. The relevant strain-induced changes in electronic properties arise from band structure modifications at the Fermi level as a consequence of a spin-polarized charge transfer between p-orbitals of the N and A1 edge atoms in a spin-resolved self-doping process. This band structure tunability indicates the possibility of designing magnetic nanoribbons with tunable electronic structure by deriving edge states from elements with sufficiently different localization properties. Finite temperature molecular dynamics reveal a thermally stable half-metallic nanoribbon up to room temperature.

Facile construction of quasi 1D trimanganese tetraoxide nanostructures via soft templating

Self-assembly of nanocrystals can not only lead to a better understanding of inter-particle acting force, but also enable rational building of complex and functional materials for future nanodevices. Here by utilizing polyvinylpyrrolidone （PVP） as the as capping and structure directing agents, hierarchical Mn304 architectures involving coil-like nanorings, hexagonal nanoframes, and nanodisks are conveniently synthesized by a one-pot solution method. The sophisticated assemblies are proven to be me- diated by the PVP soft templates formed at varied concentrations. The driving forces of self-assembled complex nanostructures and the unique role of PVP concentration are discussed. Magnetic properties of the as assembled Mn3O4 rings are also studied by a SQUID system, which shows the typical side effect of Curie temperature.