基于HMM的瞬态回波分类研究

本文从瞬态回波与语音信号在非线性时变方面的相似性出发,分析了隐马尔可夫模型用于瞬态回波分类的可行性并选择了一种较合的ＨＭＭ结构对两类仿真回波信号进行了分类,取得了较好的效果。     

Influence of the proximity effect on the energy resolution of STJs

The generating function describing statistical processes of X-ray registration in a superconducting tunnel junction (STJ) with proximized electrodes, and the influence of the proximity effect on the mean value of the signal and the energy resolution of the STJ is derived.     

瞬态回波边缘特征与水下目标分类

瞬态回波在水下目标探测方面具有比稳态回频谱宽、反隐身性能好的优点。本研究了利用小波变换提取水下目标瞬态回波的边缘特征并进行目标分类的可行性。对试验数据处理的结果表明，该方法有一定研究价值。     

The relaxation times of an STJ detector: Role of the proximity effect

The behavior of a superconducting tunnel junction detector (STJ) in the regime of low excitation is described, and the characteristic times of the dynamical response are discussed. The effect of a proximity layer in the STJ is analyzed in terms of the McMillan model. A set of phenomenological equations for the proximized STJ driven out of equilibrium is obtained, showing the importance of the role of the proximity effect in the dynamics of the device.     

Pair breaking as a probe of d-wave high-temperature superconductivity

A unified picture is obtained of the Cooper pair-breaking data by Cu-site Zn and Ni in Nd_2–z Ce _z CuO₄, La_2–SrCuO₄, Bi₂Sr₂CaCu₂O₈, Bi_1.8Pb_0.2Sr₂Ca₂Cu₃O₁₀, YBa₂Cu₃O₇, and YBa₂Cu₄O₈. The data are generally inconsistent with spin-fluctuation d-wave pairing mechanisms of superconductivity and with all two-dimensional cuprate-plane models. The data are consistent with superconductivity in the charge reservoirs.     

The influence of proximity dimensions on international research collaboration: an analysis of European water projects

In this paper we investigate the effect of geographical, organisational and social proximity on the propensity of organisations to collaborate internationally in knowledge production. We apply logistic regression models on data from water research projects in the European Union’s Framework Programme 1–7. Although the main challenges in the water sector typically cut across borders, knowledge development is traditionally organised in national systems. These systems have a long tradition in collaborating across societal sectors. Despite the fact that about half of the collaborations in the Framework Programmes are not proximate at all, we show that all three proximity dimensions contribute to the propensity to collaborate. The three dimensions of proximity are weakly correlated, and there is a small substitution effect between organisational and geographical proximity.     

水下目标壳体的镜反射亮点回波结构

文章从工程应用角度讨论水下目标壳体镜反射亮点回波结构。在声呐频率范围内把水下目标壳体作为多层平板处理。应用声线方法和递推关系导出任意多层平板的反射系数。忽略耦合水层两边的多次反射后，得到一组适合于瞬态和亮点分析的反射系数近似公式。利用这组公式依次讨论了：（1）未敷设吸声覆盖层的单层壳体；（2）未敷设吸声覆盖层的双层壳体；（3）敷设吸声覆盖层的单层壳体；（4）敷设吸声覆盖层的双层壳体等4种情况的镜反射亮点回波结构。并给出了数值计算的算例。     

Personal and social proximity empowering collaborations: the glue of knowledge networks

The proximity framework serves to analyse and understand how collaborations form and develop over time, and how these affect innovation and learning. The framework has inspired and informed empirical studies in several contexts, contributing to our understanding of the dynamics of dyadic collaborations, industrial clusters and districts, and regional innovation systems, to name but a few. Recent conceptual and empirical advances have called attention to the role of personal proximity and social proximity in such collaborations. In addition to other forms of proximity, these two dimensions could make up the glue that holds knowledge networks together. In the introduction to this special issue, we elaborate upon this proposition, setting out a point-of-departure for the three empirical studies collected in this issue. We summarize the findings of these papers, and develop a research agenda from those findings that may guide proximity researchers to novel research problems and useful research designs.     

Size effect: Influence of proximity of fracture process zone to specimen boundary

Size effect on strength of cementitious materials was studied successfully many years ago by a crack-bridging model through detailing the influence of the resistance R-curve behaviour on quasi-brittle fracture. The condition that specimens of different sizes have to be geometrically similar, commonly assumed for size effect study, was proven unnecessary. The present study emphasizing the interaction between the fracture process zone and structure boundary agrees with the crack-bridging analysis, and further points out that physical size itself is not the key mechanism for the apparent size effect.     

Evaluation of a radar-based proximity warning system for off-highway dump trucks

A radar-based proximity warning system was evaluated by researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health to determine if the system would be effective in detecting objects in the blind spots of an off-highway dump truck. An average of five fatalities occur each year in surface mines as a result of an equipment operator not being aware of a smaller vehicle, person or change in terrain near the equipment. Sensor technology that can detect such obstacles and that also is designed for surface mining applications is rare. Researchers worked closely with the radar system manufacturer to test and modify the system on large, off-highway dump trucks at a surface mine over a period of 2 years. The final system was thoroughly evaluated by recording video images from a camera on the rear of the truck and by recording all alarms from the rear-mounted radar. Data show that the system reliably detected small vehicles, berms, people and other equipment. However, alarms from objects that posed no immediate danger were common, supporting the assertion that sensor-based systems for proximity warning should be used in combination with other devices, such as cameras, that would allow the operator to check the source of any alarm.     

Boosting the superconducting spin valve effect in a metallic superconductor/ferromagnet heterostructure

Superconducting spin valves based on the superconductor/ferromagnet (S/F) proximity effect are considered to be a key element in the emerging field of superconducting spintronics. Here, we demonstrate the crucial role of the morphology of the superconducting layer in the operation of a multilayer S/F1/F2 spin valve. We study two types of superconducting spin valve heterostructures, with rough and with smooth superconducting layers, using transmission electron microscopy in combination with transport and magnetic characterization. We find that the quality of the S/F interface is not critical for the S/F proximity effect, as regards the suppression of the critical temperature of the S layer. However, it appears to be of paramount importance in the performance of the S/F1/F2 spin valve. As the morphology of the S layer changes from the form of overlapping islands to a smooth case, the magnitude of the conventional superconducting spin valve effect significantly increases. We attribute this dramatic effect to a homogenization of the Green function of the superconducting condensate over the S/F interface in the S/F1/F2 valve with a smooth surface of the S layer.

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The different roles of proximity in multiple informal network relationships: evidence from the cluster of high technology applied to cultural goods in Tuscany

The role of proximity in innovation and inter-organisational networks has received increasing attention over the past decade. Despite the rich literature, most contributions principally focus on only one type of relationship and mainly consider formal relationships such as R&;D partnerships, EU projects or patents. The aim of the study is to investigate the role of various forms of proximity in multiple informal inter-organisational relationships. The article focuses on two research questions: (i) How do the various forms of proximity influence the formation of different informal relationships? and (ii) What is the impact of social ties on relationships for innovation? ERGM is applied to measure the different impact of the proximities on three network relationships operating in the cluster of High Technology applied to Cultural Goods. The results underline the heterogeneous impact of various forms of proximity on the different relationships and the strong impact of social ties on innovation.     

Pair Interaction between Two Catalytically Active Colloids

Due to the intrinsically complex non-equilibrium behavior of the constituents of active matter systems, a comprehensive understanding of their collective properties is a challenge that requires systematic bottom–up characterization of the individual components and their interactions. For self-propelled particles, intrinsic complexity stems from the fact that the polar nature of the colloids necessitates that the interactions depend on positions and orientations of the particles, leading to a 2d − 1 dimensional configuration space for each particle, in d dimensions. Moreover, the interactions between such non-equilibrium colloids are generically non-reciprocal, which makes the characterization even more complex. Therefore, derivation of generic rules that enable us to predict the outcomes of individual encounters as well as the ensuing collective behavior will be an important step forward. While significant advances have been made on the theoretical front, such systematic experimental characterizations using simple artificial systems with measurable parameters are scarce. Here, two different contrasting types of colloidal microswimmers are studied, which move in opposite directions and show distinctly different interactions. To facilitate the extraction of parameters, an experimental platform is introduced in which these parameters are confined on a 1D track. Furthermore, a theoretical model for interparticle interactions near a substrate is developed, including both phoretic and hydrodynamic effects, which reproduces their behavior. For subsequent validation, the degrees of freedom are increased to 2D motion and resulting trajectories are predicted, finding remarkable agreement. These results may prove useful in characterizing the overall alignment behavior of interacting self-propelling active swimmer and may find direct applications in guiding the design of active-matter systems involving phoretic and hydrodynamic interactions.     

吸收式制冷工质的发展

吸收式制冷机诞生至今已有一百多年的时间了,在这一百多年中,吸收式制冷技术获得了长足的进步和发展。与此同时,吸收式制冷机制冷工质的选择及改善作为吸收式制冷技术的核心组成部分也得到了不断的完善和发展。吸收制冷工质对选择的每一次突破,都对吸收式制冷技术的进步产生了巨大的推动作用。本文简要回顾了吸收式制冷工质的发展过程,分析比较了当今正在研究或使用的主要工质对,同时也介绍了我们浙江大学制冷与低温工程研究所正在研究的Ｒ２２／ＤＭＦ（二甲基甲酰胺）和Ｒ２２＋Ｒ１４２ｂ／ＤＭＦ工质对的有关情况。     

吸附式制冷工质对的研究进展

介绍了吸附式制冷的工作原理,综述了近年来国内外吸附制冷中吸附工质对的研究进展,同时也介绍了我们正在研究的耦合吸附吸收制冷循环中以双组分氨-水为制冷工质的研究状况.     

The proximity effect of the normal-superconducting superlattice

We propose an iterative procedure to solve the linearized Gorkov equation and calculate the superconducting critical temperature of superconductor-normal metal superlattice in the whole region of layer thickness. We also give a discussion of the validity range of the local approximation made on the proximity effect of SN superlattice.     

弹性双圆柱在均匀流场中动态响应的实验研究

本文针对T/D=1.75、2.5、3.5并列弹性双圆柱在均匀流场中的动态特性进行了实验研究.测出了两柱在横向及流向的动态响应.经分析,本文给出了两圆柱在横向及流向的振动频率及振幅随两柱间距及约化速度的变化关系.同时对弹性柱的Strouhal数给予了适当的讨论.     

The Strong Impact of the Weak Superconductivity

The Josephson effect offers an unparalleled tool to shed light on aspects of the underlying physics of phenomena which go also far beyond the field of superconductivity. Some considerations on a few examples of the highlights concerning both exciting achievements and challenging perspectives of this fascinating topic are briefly outlined sharing the attention on both possible applications and intriguing implications.     

NIM新一代二端对电容电桥装置

基于一种交流电桥自动辅助平衡方法,中国计量科学研究院(NIM)研制了新一代二端对电容电桥装置。电桥采用固定比率的感应耦合比率臂电桥,通过复用比率,用单一电桥即实现了计算电容过渡和电容10:1传递;采用一种改进的靴带法实现电桥感应比率臂比率的精确校验。该装置用于电容单位的量值复现和标准电容器的高准度量值传递。利用新一代二端对电容电桥装置,可从计算电容装置复现1 pF电容值,并实现电容 1~100 pF的十进制量值传递,电容量值传递相对标准不确定度可达5×10^-9(1592 Hz)。采用该电桥参加了10 pF和100 pF电容国际关键比对(CCEM.K4-2017),中国比对成绩优异,数据均非常接近关键比对参考值(KCRV),其中100 pF的结果最接近KCRV,与KCRV取得了很好的一致性,从而获得国际互认。     

A possible explanation for the isotope effect in high-Tc and Rb3C60 superconductors

The role of pair breaking effects on the isotope effect coefficient is investigated using the generalized Abrikosov and Gorkov theory of superconductors. It is found that the pair breaking effects enhance the isotope effect coefficient. This provides a plausible explanation for the enhancement of the isotope effect coefficient as a function of impurity concentration in yttrium-, europium-, and lanthanum-based high-T _c superconductors. It may also explain the very large value of the isotope effect coefficient in Rb₃C₆₀ superconductors provided some intrinsic disorder is assumed.