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：高效非贵金属催化剂对于推进析氢反应(HER)的大规模工业化至关重要.碳化钼(Mo_(2)C)因其类似铂的能带密度和优良的中间产物吸附特性,有望替代贵金属基材料成为具有前景的催化剂.然而,它在常规制备过程中存在严重的晶体过度生长和团聚问题,导致催化效率低.本研究利用三聚氰胺辅助法制备了含有丰富表面和界面的超细碳化钼/氮化钼(Mo_(2)C/Mo_(2)N)异质结构,并同时将其嵌入到氮掺杂碳纳米纤维(CNFs)中.Mo_(2)C/Mo_(2)N异质结构的协同作用与超细纳米晶表面暴露的丰富活性位点共同提高了电催化活性,而氮掺杂碳纳米纤维框架保证了快速的电荷转移和良好的结构稳定性.此外,原位形成的Mo_(2)C/Mo_(2)N晶体与碳基质之间存在较强的界面耦合作用,进一步提高了电子电导率和电催化活性.得益于这些优势,Mo_(2)C/Mo_(2)N@N-CNFs在碱性溶液中表现出优异的电催化析氢性能,在电流密度10 mV cm^(-2)时具有75 mV的低过电势,优于单相Mo_(2)C@N-CNFs对比样以及近期报道的Mo_(2)C/Mo_(2)N基催化剂.这个合成方法集成了异质结构、纳米化和碳修饰策略,为设计高效率电催化材料提供了新的参考.

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.