摘要：The DC-DC converters are widely used in photovoltaic generating systems as an interface between PV module and the load. These converters must be chosen to be able to match the maximum power point (MPP) of PV module when climatic conditions change with different resistive load values. So DC-DC converters must be used with MPPT controller in order to reduce losses in the global PV system. This article focuses on the effect of climatic conditions on design of two components (inductance, capacitance) for three topologies of DC-DC converters commonly used in PV systems. When climatic conditions change, the boundary of inductance and capacitance parameters of DC-DC converter will change. These two parameters must be properly sized to achieve optimal efficiency for each converter. The design optimization is based on two principles: 1) for a steady-state operation in a continuous conduction mode, the inductance value for all choppers must be greater than the maximum value of boundary inductance, and 2) in order to limit the output voltage ripple of DC-DC converter below a desired value, the filter capacitance must be larger than the maximum value of boundary capacitance.

摘要：近年来,基于磁共振和近场耦合的非辐射无线能量传输技术已被广泛应用.然而,由于传输效率和功率随着距离增加而大幅降低,基于双谐振器的无线能量传输系统仅适用于中短距离应用.基于多中继谐振器的无线能量传输系统可克服该问题,然而该复杂系统对微扰和缺陷极为敏感.针对上述问题,本文实验验证了稳健性拓扑无线能量传输.电磁能量可通过位于一维无线电波拓扑绝缘体两端的拓扑边界态之间的近场耦合高效传递.该结构可等效为具有复边界电势的宇称-时间对称的Su-Schrieffer-Heeger链.此外,所设计的线圈结构可抑制不相邻线圈之间非必要的交叉耦合.该工作理论和实验上验证了即使存在微扰的情况下,该系统仍可在拓扑边界态的奇异点附近保持极高的能量传输效率.该工作将拓扑电磁材料、非厄米物理和无线能量传输技术三者结合,为未来电子、交通运输和工业中的长距离无线传输提供稳定、高效的平台.

摘要：过渡金属磷化物(TMPs)/碳复合材料的设计合成在储能领域逐渐引起了研究人员的关注.本研究以镍基-金属有机骨架材料为模板将磷化镍(Ni2P)纳米颗粒嵌入到氮掺杂碳(Ni2P/NC)多孔微球中.全面碳封装结构使得Ni2P纳米颗粒之间的接触更加紧密,大大提高了结构的完整性和导电性,使得储锂性能更加优异.即使在电流密度为3.0Ag^-1的情况下,可逆比容量仍可达286.4mAhg^-1.在0.5Ag^-1电流密度下连续充放电循环800次后,仍可获得450.4mAhg^-1的可逆比容量.本研究证实了Ni2P/NC微观结构的可逆性.此外,基于LiNi1/3Co1/3Mn1/3O2||Ni2P/NC的全电池展示了良好的倍率性能和循环寿命.本研究为寻找应用于储能装置的先进电极材料提供了有力而深入的理论依据.

摘要：本文以具有聚集诱导发光(AIEgen)的三联吡啶衍生物为配体,构建了一种新型配位聚合物(CP)光学材料.该材料可以从中心对称结构(1-α相)自发相变成非中心对称结构(1-β相),两种物相均能可控合成,且通过单晶X射线衍射清晰表征相变前后结构.有趣的是,中心对称1-α相转变为非中心对称1-β相,从而产生强相位匹配二次谐波(SHG)响应,约为KH2PO4(KDP)的4.5倍.为了更好地理解结构与非线性光学特性之间的关系,对偶极矩进行了计算和讨论.值得注意的是,1-β具有高热稳定性的非中心对称结构,在1-α结构相变后保留并改善了AIEgen配体的初始发光性质,同时产生了新的优异的SHG性质,这为设计和制备优良的光学材料提供了一条很好的途径.

摘要：GaN (gallium nitride) buck-rectifier has been proposed to realize high power density ISOP (input series and output parallel)-IPOS (input parallel and output series) converter-based dc distribution system. The ultra-low loss bi-directional switch can be developed by the GaN power device because of the low on-resistance, the high-speed switching behavior and its own device structure. The buck-rectifier using the GaN bi-directional switches has the potential to achieve higher power density than the commonly utilized boost-rectifier. Availability of the GaN-HEMT (high electron mobility transistor) for the buck rectifier has been verified taking the theoretical limit of the on-resistance and the switching loss energy into account. Design consideration for a high power density buck-rectifier has been also conducted and the application effect of the GaN bidirectional switches has been evaluated quantitatively. The ISOP-IPOS converter-based dc (direct current) distribution system takes full advantage of the buck-rectifier and the rectifier using GaN devices contributes to realizing higher power density dc distribution system.