视觉约束的增强三角剖分指纹识别算法

针对低质量指纹的真实细节点缺失和伪细节点增加以及典型指纹识别算法对细节点准确性过于依赖的问题,提出了视觉约束的增强三角剖分指纹识别算法。首先根据所提取细节点利用三角形重构获得增强三角剖分集;然后计算三角形特征向量,使用递减验证进行三角形匹配确定匹配细节点对,并使用视觉约束优化;最后根据匹配点对的比例获得相似度从而完成识别。采用国际标准测试库FVC2000DB2、FVC2006DB2和FVC2006DB3进行综合性能比对实验,该算法等错误率（EER）分别为432%、264%和798%,相比改进前的Delaunay 三角剖分降低了128%、171%和283%,相比改进前的扩展三角剖分降低了126%、052%和258%,相比尺度不变特征转换（SIFT）算法分别降低了089%、297%和003%。实验结果表明,所提算法无需校准且对低质量指纹导致的真实细节点缺失和增加的伪细节点有较好的适应能力。     

Dual-Responsive Soft Actuator Based on Aligned Carbon Nanotube Composite/Graphene Bimorph for Bioinspired Applications

Nanocarbon-based polymer actuators have attracted significant attention because of their excellent actuation performance. In this study, a soft bimorph actuator composed of an anisotropic carbon nanotube (CNT)–polymer composite and reduced graphene oxide (rGO) film is fabricated by a simple blade-coating method. Owing to the excellent electrical, optical, and thermal properties of the CNT and rGO, the actuator exhibits dual-responsive actuation. It generates reversible bending deformation with a displacement of ≈13 mm under low electrical voltage stimulation or white light irradiation. Furthermore, because of the embedment of aligned CNTs in polymer matrix, this actuator exhibits excellent mechanical output compared with many of the reported nanocarbon-based actuators. It can lift a 2.048 g clip to a height of ≈5 mm under low electrical voltage stimulation. Based on this soft actuator with dual response and good mechanical output, various bionic devices are designed. A bionic eagle claw that grasps a soft object under electrical stimulation and an artificial flower blooming in response to light irradiation are constructed. Moreover, a light-driven smart curtain and a seagull robot are fabricated. These results reveal the great potential of the dual-responsive anisotropic soft actuator in soft robots and smart devices driven by electricity and light.     

基于GaN全桥LLC谐振变换器交错并联系统的损耗分析

为提高全桥LLC谐振变换器交错并联(FBLLC-SP)系统的效率,且使其理论损耗与实际运行损耗更贴近,对比Cascode型GaN HEMT向系统引入单体增强型GaN HEMT,并将其寄生参数引入到损耗模型中,建立了一种适用于单移相(SPS)开环控制和三移相(TPS)双闭环控制的FBLLC-SP系统精准损耗模型;给出最佳死区时间计算方法,并分析了FBLLC-SP系统在单移相(SPS)开环控制下的理论损耗,提出了不同模态GaN HEMT的暂态损耗和各种通态损耗的精准计算方法;搭建了FBLLC-SP系统损耗模型仿真系统。实验结果表明:本文损耗模型的损耗值比系统实际运行损耗最多高约0.6%,说明本文建立的精细化损耗模型可用于分析系统的实际运行损耗。     

运行条件对强化生物除磷颗粒污泥系统性能及微生物群落的影响

为了了解SBR强化生物除磷（EBPR）颗粒污泥系统的影响因素,为颗粒污泥生物除磷工艺的实际应用提供技术支持,采用有效容积为12 L的SBR反应器,以乙酸钠为碳源、KH₂PO₄为磷源,对EBPR颗粒污泥系统的启动和除磷性能及污泥颗粒化过程进行研究。结果表明：若进水碳磷比过低（C：P=200：15）,除磷效率较低。与25℃相比,15℃条件下污泥EPS含量增加。此外,15℃条件下污泥颗粒化的蛋白质（PN）含量增加更为显著,污泥粒径增长明显,且与25℃相比,在15℃的低温条件下,更利于传统EBPR系统中主要负责生物除磷的微生物红环菌属（Rhodocyclus）的生长,使其成为系统优势菌种,进而提高除磷效率。     

A new one‐point quadrature enhanced assumed strain (EAS) solid‐shell element with multiple integration points along thickness: Part I—geometrically linear applications

Accuracy and efficiency are the main features expected in finite element method. In the field of low‐order formulations, the treatment of locking phenomena is crucial to prevent poor results. For three‐dimensional analysis, the development of efficient and accurate eight‐node solid‐shell finite elements has been the principal goal of a number of recent published works. When modelling thin‐ and thick‐walled applications, the well‐known transverse shear and volumetric locking phenomena should be conveniently circumvented. In this work, the enhanced assumed strain method and a reduced in‐plane integration scheme are combined to produce a new eight‐node solid‐shell element, accommodating the use of any number of integration points along thickness direction. Furthermore, a physical stabilization procedure is employed in order to correct the element's rank deficiency. Several factors contribute to the high computational efficiency of the formulation, namely: (i) the use of only one internal variable per element for the enhanced part of the strain field; (ii) the reduced integration scheme; (iii) the prevention of using multiple elements' layers along thickness, which can be simply replaced by any number of integration points within a single element layer. Implementation guidelines and numerical results confirm the robustness and efficiency of the proposed approach when compared to conventional elements well‐established in the literature. Copyright © 2004 John Wiley & Sons, Ltd.     

High-speed cinematography of gas-metal atomization

A high-speed cinematographic footage of a 304L stainless steel gas atomization, recorded at the National Institute of Standard and Technology (NIST), was analyzed using a discrete Fourier transform (DFT) algorithm. The analysis showed the gas atomization process possesses two prominent frequency ranges of melt oscillation (pulsation). A low-frequency oscillation in the melt flow occurring between 5.41 and 123 Hz, with a dominant frequency at 9.93 Hz, was seen in the recirculation zone adjacent to the melt orifice. A high-frequency melt oscillation range was observed above 123 Hz, and was more prominent one melt-tip-diameter downstream in the melt atomization image than upstream near the melt tip. This high-frequency range may reflect the melt atomization frequency used to produce finely atomized powder. This range also included a prominent high frequency at 1273 Hz, which dominated in the image further away downstream from the melt tip. This discrete high-frequency oscillation is most probably caused by the aeroacoustic “screech” phenomenon, intrasound (<20 kHz), a result of the atomizing gas jets undergoing flow resonance. It is hypothesized that this discrete intrinsic aeroacoustic tone may enhance melt breakup in the atomization process with evidence of this fact in the melt images.     

镁盐晶须增强材料的研究及应用

详细阐述了硼酸镁、碱式硫酸镁晶须和氧化镁晶须等镁盐晶须的合成方法,着重介绍了镁盐晶须作为增强材料在金属铸造、复合材料、塑料等行业的应用。     

时空ER模型的设计

为了满足时空数据库设计的需要，提出了新的时空ER模型并给出了相关的概念及设计方法。这种模型可以方便时空数据的建模，为数据库的设计提供有效的方法。     

深部调驱用弱凝胶有机铬交联剂的合成与性能

根据络合剂的络合常数，以单糖化合物为配位体合成出一种用于深部调驱用弱凝胶有机铬交联剂。研究结果表明，该交联体系施工方便，易于注入，性能优良，可有效解决原油层垂直和平面矛盾，提高采收率。     

相变蓄热电暖器的制作及性能测试

针对许多地区电力出现相对过剩、电力峰谷差不断拉大的现象,开发了一种在低谷电时段蓄热、在用电高峰时放热的相变蓄热电暖器。此装置采用电加热管直接加热,为了强化内部传热,在设备中加装了内翅片,实验结果表明内翅片起到很好的强化传热作用。测出了充放热过程设备中相变蓄热材料温度和出风温度,绘制了相变材料温度及出风温度随时间的变化曲线,由此曲线可明显看出材料的相变过程。通过对测试结果分析可知,此设备具有体积小、蓄热量大、放热温度均匀、便于控制等特点。可在低谷时段蓄热,在用电高峰时放热,起到了降低用户费用,充分利用电力资源的作用,此设备适合用于替代以往部分电采暖设备。