面向滑动窗口应用的设计空间探索方法

面向滑动窗口应用,提出一种设计空间探索算法,通过判断芯片面积、存储带宽和存储资源3种片上资源约束的上限,实现充分利用片上资源．实验结果表明,该算法可以将存储资源利用率提高85％以上;同时,与相关工作相比,文中的阵列分块方法可以将访存次数降低2％～20％．     

Field cross correlator for analysis of ultrafast signals

The cross-correlation function between two light fields is recorded with the help of a new device. The proposed correlator exhibits ultrashort time resolution. The optical path difference between the two interfering beams does not have to be known with interferometric precision. The experimental dynamic range proved to be as large as 10(5). The device features imaging capabilities that could be applied to the analysis of two-dimensional images with ultrashort time resolution.     

Self-pumped phase-conjugation properties of cerium-doped BaTiO(3) crystals in the near infrared

Studies of a new Ce-doped BaTiO(3) crystal as an efficient self-pumped phase conjugator in the near infrared are presented. The internal beam production during the establishment of self-pumped phase conjugation (SPPC) is closely observed, and the corresponding mechanisms of SPPC are identified accordingly. When the incident beam is in an a-face-incidence geometric arrangement, it is observed for the first time that SPPC mechanism has a transition from stimulated photorefractive backscattering and four-wave mixing to total internal reflection when λ is varied from 706 to 733 nm. Variations of the SPPC reflectivity with the λ, incident angle, and position of the input beam have been investigated, and a high reflectivity of approximately 80% has been obtained. In addition, SPPC reflectivity of approximately 40% is obtained when the incident beam enters the crystal by the +c face, and a variation with λ of optical beam patterns in the crystal has also been observed. Qualitative explanations of the phenomenon of SPP mechanism transition with λ that will be very useful in practical applications are given.     

On the significance of data bases keywords for alarge scale bibliometric investigation in fundamental physics

We present an automatized bibliometric investigation applied to the field of fundamental research in physics. We briefly describe the scientific context motivating this study and the statistical method used for analyzing the data. We discuss in more detail how we adapted our investigation to the questions motivating this study, namely the identification of relevant groups working in a well defined subfield of physics. We next present the results of our investigation. We particularly focus on an analysis of Index and Free terms, as obtained from the INSPEC data base we used for performing the bibliometric investigation. We discuss the relevance of Index and Free terms by means of a separation between Noise, Interesting and Trivial entries. We show that Index and Free terms exhibit somewhat different behaviors when considered as distributions in terms of frequencies of occurrence in the references. We show the particular relevance of Free terms in this analysis. This may be connected to the emerging nature of the subfield of physics under consideration. This shed an interesting light on the respective importance of Index and Free terms, as entries of data bases, in particular in the case of rapidly evolving scientific domains.     

基于 CEEMDAN 与改进核极限学习机的S700K 转辙机健康状态诊断

针对S700K转辙机健康状态分类过于粗放、诊断速度慢、效率低的问题,提出一种基于CEEMDAN与改进核极限学习机(kernel based extreme learning machine, KELM)的诊断方法。首先,对S700K转辙机功率数据进行自适应噪声完备集合经验模态分解,得到6个本征模态函数(intrinsic mode function, IMF);然后,计算本征模态函数的模糊熵值(fuzzy entropy, fuzzyEn, FE)作为表征转辙机健康状态的特征参数;最后,利用麻雀算法(sparrow search algorithm, SSA)改进的核极限学习机对9种健康状态进行健康诊断,并与SVR和ELM模型进行对比。仿真结果表明,改进核极限学机模型准确率、精确率、召回率等指标分别达到97.8%、98.0%、97.8%,相较于SVR和ELM模型,SSA-KELM模型在保证运行速度的基础上,将诊断准确率至少提高2.2%。     

Photocatalytic Valorization of Plastic Waste over Zinc Oxide Encapsulated in a Metal–Organic Framework

The conversion of waste plastic into high-value-added chemicals is regarded as a promising approach for relieving global plastic pollution and contributing to the circular economy. Herein, a partial calcination strategy is developed to fabricate a zinc oxide/UiO66-NH₂ (ZnO/UiO66-NH₂) heterojunction, in which ZnO is encapsulated in porous UiO66-NH₂ for the photocatalytic valorization of plastic. This strategy preserves the framework structure of UiO66-NH₂, thus enabling the formation of ZnO with ultra-small size distributed inside the skeleton. The synergistic effect of the obtained ZnO/UiO66-NH₂ heterojunction facilitates providing an efficient channel for carrier/mass transfer and guarantees structural stability. As a result, ZnO/UiO66-NH₂ exhibits high activity for converting polylactic acid (PLA) and polyvinyl chloride (PVC) into acetic acid, coupled with H₂ production. This work provides a feasible strategy for rationally designing heterojunction photocatalysts, as well as an insight into understanding the process of photocatalytic valorization of plastic.     

Pre-Protonated Vanadium Hexacyanoferrate for High Energy-Power and Anti-Freezing Proton Batteries

Proton batteries have been considered as an innovative energy storage technology owing to their high safety and cost-effectiveness. However, the development of fast-charging proton batteries with high energy/power density is greatly limited by feasible material selection. Here, the pre-protonated vanadium hexacyanoferrate (H-VHCF) is developed as a proton cathode material to alleviate the capacity loss of proton-free electrode materials during electrochemical tests. The pre-protonation process realizes fast and long-distance transport of protons by shortening diffusion path and reducing migration barriers. Benefitting from the enhanced hydrogen bonding network combined with dual redox reactions of V and Fe in protonated H-VHCF cathode, a high energy density of 74 Wh kg⁻¹ at 1.1 kW kg⁻¹, and a maximum power density of 54 kW kg⁻¹ at 65 Wh kg⁻¹ is achieved for the asymmetric proton batteries coupling with MoO₃/MXene anode. Proton transport and double oxidation-reduction center are verified by theoretical calculations and ex situ experimental measurements. Considering the anti-freezing availability of proton batteries, 82.5% of its initial capacity is maintained after 10000 cycles under −40 °C at 0.5 A g⁻¹. As a proof-of-concept, flexible device fabricated by optimized electrodes and hydrogel electrolytes can power up a light-emitting diode even under a bent state.     

Adaptive fuzzy leader-follower consensus control using sliding mode mechanism for a class of high-order unknown nonlinear dynamic multi-agent systems

In this article, a distributed leader-follower consensus approach is developed for a class of high-order unknown nonlinear dynamic multi-agent systems (MASs). Because every agent of the MAS contains multiple state variables, the existing consensus methods are not completely applicable for it. In order to find the qualified consensus protocol for this high-order MAS, sliding mode mechanism can be naturally considered for designing the consensus control because it can manage multiple state variables with the help of a constructed hyperplane. To this consensus control design, the sliding mode term is composed of all tracking error variables. Since the method does not require the switching control term around sliding surface, it can avoid the chattering phenomenon, which exits in most of the published sliding mode controls (SMCs). Furthermore, to handle the unknown nonlinear dynamic problem, the adaptive approximation strategy is implemented by employing fuzzy logic system (FLS). In the light of Lyapunov stability analysis, it is demonstrated that the proposed control approach can accomplish the consensus tasks. Finally, a numerical example is implemented to further show the desired results.     

铌酸钾钠基1-3型压电复合物的制备及其性能研究

采用传统固相法制备了在1 130 ℃下烧结而成的(K_0.45Na_0.55)_0.98Li_0.02(Nb_0.77Ta_0.18Sb_0.05)O₃(KNLNTS)无铅压电陶瓷。陶瓷致密度和电学性能较好,致密度达到98%,室温压电常数为308.7 pC/N,厚度振动机电耦合系数可达0.5,1 kHz时介电损耗为0.043。以上述KNLNTS基粉体为原料,利用切割填充法制备1-3型压电复合材料并研究了厚度对复合材料的性能影响。结果表明,复合材料的压电常数、厚度振动机电耦合系数均随厚度的增加而增加,介电损耗随厚度的增加而减少,而相对介电常数基本保持不变。     

1-3型压电复合材料的机电响应特性和温度稳定性

1-3型压电复合材料具备优异的机电耦合性能,这对于高性能压电换能器的开发具有重要意义。该文采用低成本的切割填充法制备了不同结构参数的1-3型PZT/环氧树脂复合材料,并结合有限元模拟法对其压电性能、机电响应特性和温度稳定性进行了系统地研究。1-3阵列结构对平面方向应变产生了很大的衰减,使能量更集中于厚度共振模式。复合材料的高径比是影响机电耦合性能的主要因素,更精细的阵列结构有利于高性能压电换能器的制造。在-20~60 ℃内,1-3型压电复合材料的厚度机电耦合系数约为0.61,变化率小于1%,表现出良好的温度稳定性。