恒流二极管分压的悬浮脉冲单臂桥驱动器研制

设计了一种恒流二极管分压的悬浮脉冲单臂桥驱动器。先介绍了悬浮脉冲驱动模块电路结构和工作原理,以及恒流模块中恒流二极管的特性、恒流二极管串联均压计算方法;再利用该原理设计了验证电路,并应用在半桥式拓扑结构的开关电源中。验证电路的测试结果表明:恒流二极管分压的悬浮脉冲单臂桥驱动器的性能完全满足设计要求,值得推广。     

WENO格式与虚拟单元浸入边界法在笛卡尔网格中的应用

高精度有限差分WENO格式在结构网格上处理具有复杂几何外形绕流问题时较困难,而虚拟单元浸入边界法却是一种较新颖且对网格的要求较低的方法,适用于复杂几何外形边界的处理.为此,在笛卡尔网格上采用WENO格式以求解Euler守恒律方程,试图将两者有效结合起来,希望能在笛卡尔网格上处理具有复杂几何外形的物体绕流问题.最后,几个经典数值算例的结果验证了该方法的有效性.     

一种新的无线传感器网络节点定位算法

无线传感器网络中的节点定位问题一直是一个倍受国内外关注的问题,由此已经提出了很多定位算法,并取得了很好的成果。在总结已有成果的基础上,受到图论的启发,将无线传感器网络当成是一个连通的节点无向图,提出了一种改进的贪婪算法,提高了算法跳出局部最优的能力。该算法采用单个移动锚节点遍历整个图,从而实现了对所有节点的定位。分析与实验表明该方法在定位精度和系统能量消耗方面都具有很好的性能。     

Robust face recognition via occlusion dictionary learning

Sparse representation based classification (SRC) has recently been proposed for robust face recognition. To deal with occlusion, SRC introduces an identity matrix as an occlusion dictionary on the assumption that the occlusion has sparse representation in this dictionary. However, the results show that SRC's use of this occlusion dictionary is not nearly as robust to large occlusion as it is to random pixel corruption. In addition, the identity matrix renders the expanded dictionary large, which results in expensive computation. In this paper, we present a novel method, namely structured sparse representation based classification (SSRC), for face recognition with occlusion. A novel structured dictionary learning method is proposed to learn an occlusion dictionary from the data instead of an identity matrix. Specifically, a mutual incoherence of dictionaries regularization term is incorporated into the dictionary learning objective function which encourages the occlusion dictionary to be as independent as possible of the training sample dictionary. So that the occlusion can then be sparsely represented by the linear combination of the atoms from the learned occlusion dictionary and effectively separated from the occluded face image. The classification can thus be efficiently carried out on the recovered non-occluded face images and the size of the expanded dictionary is also much smaller than that used in SRC. The extensive experiments demonstrate that the proposed method achieves better results than the existing sparse representation based face recognition methods, especially in dealing with large region contiguous occlusion and severe illumination variation, while the computational cost is much lower.     

基于QAA算法的昆承湖固有光学量反演模型

基于2010年4月在昆承湖采集的野外实验数据,建立了适用于昆承湖的QAA固有光学量反演模型。结果表明:该模型可以得到较高精度的反演结果。所有验证点在411~700nm波段范围内,反演总吸收系数和实测总吸收系数的决定系数R2都高于0.984,平均相对误差ε都低于14.5%。在440、488和532nm 3个波段处,总吸收系数反演值和实测值决定系数R2分别为0.655、0.742和0.826,平均相对误差ε分别为6.5%、3.6%和3.4%,精度较高。反演后向散射系数与和参考后向散射系数在440、488和532nm处均具有较好的相关性,且532nm处反演后向散射系数与实测总悬浮物浓度决定系数为0.624,呈正相关,反演后向散射系数具有一定的可信度。该模型能够为昆承湖固有光学量的反演提供一条有效途径。     

对当前环境艺术设计专业特色人才培养模式的探讨——以湖南师范学院为例

打造高素质应用型人才是当前高校环境艺术设计专业人才培养的终极目标。本文针对湖州师范学院艺术学院环境艺术设计专业的人才培养模式进行探讨,提出了新人才培养模式的主要特色为"三性",分析了人才培养特色的实现途径"点线面"。     

箱形梁结构船体水下非接触爆炸冲击环境分析

为研究箱形梁结构船体在水下非接触爆炸作用下的冲击环境,在船体中部范围内主要受力部位设置箱形梁,并与考虑箱形梁产生的质量变化而建立的等重船模进行对比,来描述箱形梁结构对冲击环境的影响.基于Abaqus中的声固耦合算法求解2种形式船体的冲击响应,以冲击谱为工具描述船体结构的冲击环境,并给出舱内甲板层的冲击环境分布.分析归纳箱形梁的作用机理,为相关舰船设备的舾装与船体优化设计提供参考.     

Nonconfinement Structure Revealed in Dion–Jacobson Type Quasi‐2D Perovskite Expedites Interlayer Charge Transport

Dion–Jacobson (DJ) type 2D perovskites with a single organic cation layer exhibit a narrower distance between two adjacent inorganic layers compared to the corresponding Ruddlesden–Popper perovskites, which facilitates interlayer charge transport. However, the internal crystal structures in 2D DJ perovskites remain elusive. Herein, in a p‐xylylenediamine (PDMA)‐based DJ perovskite bearing bifunctional NH₃⁺ spacer, the compression from confinement structure (inorganic layer number, n = 1, 2) to nonconfinement structure (n > 3) with the decrease of PDMA molar ratio is unraveled. Remarkably, the nonconfined perovskite displays shorter spacing between 2D quantum wells, which results in a lower exciton binding energy and hence promotes exciton dissociation. The significantly diminishing quantum confinement promotes interlayer charge transport leading to a maximum photovoltaic efficiency of ≈11%. Additionally, the tighter interlayer packing arising from the squeezing of inorganic octahedra gives rise to enhanced ambient stability.     

Unravelling H+/Zn2+ Synergistic Intercalation in a Novel Phase of Manganese Oxide for High‐Performance Aqueous Rechargeable Battery

Aqueous Zn‐MnO₂ batteries using mild electrolyte show great potential in large‐scale energy storage (LSES) application, due to high safety and low cost. However, structure collapse of manganese oxides upon cycling caused by the conversion mechanism (e.g., from tunnel to layer structures for α‐, β‐, and γ‐phases) is one of the most urgent issues plaguing its practical applications. Herein, to avoid the phase conversion issue and enhance battery performance, a structurally robust novel phase of manganese oxide MnO₂H_0.16(H₂O)_0.27 (MON) nanosheet with thickness of ≈2.5 nm is designed and synthesized as a promising cathode material, in which a nanosheet structure combined with a novel H⁺/Zn²⁺ synergistic intercalation mechanism is demonstrated and evidenced. Accordingly, a high‐performance Zn/MON cell is achieved, showing a high energy density of ≈228.5 Wh kg^?1, impressive cyclability with capacity retention of 96% at 0.5 C after 300 cycles, as well as exhibiting rate performance of 115.1 mAh g^?1 at current rate of 10 C. To the best current knowledge, this H⁺/Zn²⁺ synergistic intercalation mechanism is first reported in an aqueous battery system, which opens a new opportunity for development of high‐performance aqueous Zn ion batteries for LSES.     

电动汽车冬季负荷特性研究

纯电动汽车在冬季运行时,其采暖负荷将造成续航里程严重缩短。因此,确定电动汽车空调在冬季时的负荷特性对于指导设计和控制尤为重要。对此本文使用热平衡法对电动汽车稳态负荷特性进行了实验研究,结果发现:冬季采暖负荷主要由新风负荷与车体围护结构导热负荷构成,其中新风负荷占主要部分,该负荷随车速、及鼓风机风量的增加而增加。在-20℃环境中,随车速及鼓风机档位变化,新风负荷占比为56.2%~84.8%。基于此,进一步分析计算了冬季采暖负荷及制热效率对于纯电动汽车的里程影响:NEDC工况下,冬季使用PTC取暖将会使得续航里程下降20.1%~56.4%,而使用热泵将显著延长续航里程,当热泵效率为1.7时,可延长里程7.4%~13.2%。