摘要：高温条件下WS_(2)易于氧化生成WO3,导致WS_(2)固体润滑薄膜的摩擦学性能受到较大影响。为改善WS_(2)固体润滑薄膜在高温条件下的摩擦学性能,采用非平衡磁控溅射技术制备了共掺杂La-Ti/WS_(2)复合薄膜,研究了靶功率对磁控溅射La-Ti/WS_(2)复合薄膜结构和高温摩擦学性能的影响。利用扫描电镜(SEM)、X射线衍射仪(XRD)、纳米压痕仪和X射线光电子能谱仪(XPS)分析了薄膜微观形貌、成分、力学性能、微观结构。利用高温摩擦磨损试验机研究了复合薄膜的高温摩擦学性能。结果表明,高温环境下,靶功率为20W时La-Ti/WS_(2)复合薄膜表现出优异的摩擦学性能。此时,复合薄膜H/E值最大,摩擦系数最小,平均为0.012,磨损率最低为1.56×10^(-8)mm^(3)/N·m,这主要归因于高温下摩擦界面产生的稀土氧化物,促使La-Ti/WS_(2)复合薄膜的摩擦磨损机制发生了改变,使得WS_(2)在高温受破坏的情况下仍然具有优异的摩擦学性能,从而进一步拓展了WS_(2)复合薄膜的工程应用范围。

摘要：Random dynamic responses caused by the uncertainty of structural parameters of the coupled train-ballasted track-subgrade system under train loading can pose safety concerns to the train *** paper introduced a computational model for analyzing probabilistic dynamic responses of three-dimensional(3D)coupled train-ballasted track-subgrade system(TBTSS),where the coupling effects of uncertain rail irregularities,stiffness and damping properties of ballast and subgrade layers were simultaneously *** number theoretical method(NTM)was employed to design discrete points for the multi-dimensional stochastic *** time-histories of stochastic dynamic vibrations of the TBSS with systematically uncertain structural parameters were calculated accurately and efficiently by employing the probability density evolution method(PDEM).The model-predicted results were consistent with those by the Monte Carlo simulation method.A sensitivity study was performed to assess the relative importance of those uncertain structural parameters,based on which a case study was presented to explore the stochastic probability evolution mechanism of such train-ballasted track-subgrade system.

摘要：Regulating chemical bonds to balance the adsorption and disassociation of water molecules on catalyst surfaces is crucial for overall water splitting in alkaline *** we report a facile strategy for designing Ni2W4C-W3C Janus structures with abundant Ni-W metallic bonds on surfaces through interfacial *** Ni atoms into the W3C crystals in reaction progress generates a new Ni2 W4C phase,making the inert W atoms in W3C be active sites in Ni2W4C for overall water *** Ni2W4CW3C/carbon nanofibers(Ni2 W4-W3C/CNFs)require overpotentials of 63 mV to reach 10 mA cm^-2 for hydrogen evolution reaction(HER)and 270 mV to reach 30 mA cm^-2 for oxygen evolution reaction(OER)in alkaline electrolyte,*** utilized as both cathode and anode in alkaline solution for overall water splitting,cell voltages of 1.55 and 1.87 V are needed to reach 10 and 100 mA cm^-2,*** functional theory(DFT)results indicate that the strong interactions between Ni and W increase the local electronic states of W *** Ni2W4C provides active sites for cleaving H-OH bonds,and the W3C facilitates the combination of Hads intermediates into H2 *** in situ electrochemical-Raman results demonstrate that the strong absorption ability for hydroxyl and water molecules and further demonstrate that W atoms are the real active sites.

摘要：新能源发电和负荷需求的波动性使得纳网内能源盈馀不同,从而影响本地新能源消纳水平和运行成本.本文针对纳网内暖通空调潜在的热弹性调节能力,阐述了一种基于用户舒适度偏好和环境因素的需求响应和双向定价策略,来优化纳网与公共管理中心间的能源双向交易及时均收益.所构建的双层交易随机优化模型中由于存在不确定参数和时间耦合温度队列使得长期优化问题求解复杂.为此设计了一种基于李雅普诺夫优化方法的松弛形式对原问题进行时间解耦,重构主从博弈框架来刻画参与者能量交易决策间的相互影响关系,并进一步对博弈均衡点的存在与唯一性给出严格的证明.在此基础上提出了一种优化响应算法使得决策者间能以较少的信息交换达到博弈均衡.最后通过仿真实验验证了该能量管理算法的有效性.

摘要：Spiking neural network,inspired by the human brain,consisting of spiking neurons and plastic synapses,is a promising solution for highly efficient data processing in neuromorphic ***,memristor-based neurons and synapses are becoming intriguing candidates to build spiking neural networks in hardware,owing to the close resemblance between their device dynamics and the biological ***,the functionalities of memristor-based neurons are currently very limited,and a hardware demonstration of fully memristor-based spiking neural networks supporting in-situ learning is very ***,a hybrid spiking neuron combining a memristor with simple digital circuits is designed and implemented in hardware to enhance neuron *** hybrid neuron with memristive dynamics not only realizes the basic leaky integrate-and-fire neuron function but also enables the in-situ tuning of the connected synaptic ***,a fully hardware spiking neural network with the hybrid neurons and memristive synapses is experimentally demonstrated for the first time,and in-situ Hebbian learning is achieved with this *** work opens up a way towards the implementation of spiking neurons,supporting in-situ learning for future neuromorphic computing systems.

摘要：基于几何光学理论和矢量衍射理论,设计了263 GHz DNP-NMR谱仪的改进反射镜系统,并进行了数值模拟.该系统包括两个波纹波导、一个抛物面镜和一个角度可调的相位校正镜.仿真结果表明,获得了聚焦良好的类高斯输出光束,其标量高斯模含量为99.90%,矢量高斯模含量为99.55%.只有通过调整相位校正镜的角度来匹配DNP-NMR样品,才能改变输出光束的方向.当输出光束方向在±15°变化时,标量高斯模含量约为99.57%,矢量高斯模含量约为98.97%.

摘要：酶具有优异的生物催化功能,基于此高效催化性能,体内酶促反应在生物医学领域具有广阔的应用前景.然而,目前的主要局限在于如何在体内实现酶反应的精确控制.本文设计了一种以上转换纳米颗粒为核心,以供体-受体Stenhouse加合物(DASA)分子开关为包覆层的功能化纳米平台,用于近红外光触发的体内酶促反应.在近红外辐射下,上转换纳米颗粒可以发出明亮的绿光使聚合物异构化,进而改变分子开关门控聚合物层的渗透性,使酶与底物接触发生酶促反应.分子开关聚合物的光异构化是可逆过程,调控过程不影响酶的生物活性,因此基于该纳米平台的酶反应器调控具有可逆性,实现了对酶反应的精确时空控制.利用小鼠动物模型进一步证实了近红外光对酶催化反应的时空操控.这种纳米平台不仅拓宽了DASA的应用范围,也为体内药物传递和酶替代治疗提供了新的策略.

摘要：Daytime radiative cooling with high solar refection and mid-infrared emission offers a sustainable way for cooling without energy ***,so far sub-ambient daytime radiative coolers typically possess white/silver color with limited aesthetics and *** various colored radiative cooling designs have been pursued previously,multi-colored daytime radiative cooling to a temperature below ambient has not been realized as the solar thermal effect in the visible range lead to signifcant thermal ***,we demonstrate that photoluminescence(PL)based colored radiative coolers(PCRCs)with high internal quantum effciency enable sub-ambient full-color *** an example of experimental demonstration,we develop a scalable electrostatic-spinning/inkjet printing approach to realize the sub-ambient multi-colored radiative coolers based on quantum-dot *** unique features of obtained PCRCs are that the quantum dots atop convert the ultraviolet–visible sunlight into emitted light to minimize the solar-heat generation,and cellulose acetate based nanofbers as the underlayer that strongly refect sunlight and radiate thermal *** a result,the green,yellow and red colors of PCRCs achieve temperatures of 5.4–2.2℃ below ambient under sunlight(peak solar irradiance>740 Wm),*** the excellent cooling performance and scalable process,our designed PCRC opens a promising pathway towards colorful applications and scenarios of radiative cooling.

摘要：In situ studies of catalysts play valuable roles in observing phase transformation, understanding the corresponding surface chemistry and the mechanism of the reaction. In this paper, ceria promoted cobalt oxide was prepared by the calcination method and investigated for the CO oxidation. The microstructure and morphology of CeO2-Co3O4 were investigated by the Scanning Electron Microscope, High-resolution transmission electron microscopy, Raman and X-ray photoelectron spectroscopy characterization. The effect of CeO2 doping on Co3O4 for CO oxidation was characterized by in situ X-ray Diffraction (in situ XRD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). In situ XRD was carried out under H2 atmosphere to evaluate the redox property of catalysts. The results indicated that the ceria doping can enhance the reducibility of Co2+ and promote the Co3+-Co2+-Co3+ cycle, owing to the oxygen replenish property of CeO2. Furthermore, adsorbed carbonate species on the surface of CeO2-Co3O4 were investigated by in situ-DRIFTS experiment. It was turned out that carbonate species on ceria promoted cobalt oxide catalysts showed different IR peaks compared with pure cobalt oxide. The carbonate species on ceria promoted catalyst are more active, and similar to free state carbonate species with weak bonding to catalyst surface, which can effectively inhibit catalyst inactivation. This study revealed the mechanism of ceria promoting CO oxidation over cobalt oxide, which will provide theoretical support for the design of efficient CO oxidation catalysts.

摘要：The design of electrocatalysts with enhanced adsorption and activation of nitrogen(N2)is critical for boosting the electrochemical N2reduction(ENR).Herein,we developed an efficient strategy to facilitate N2 adsorption and activation for N2 electroreduction into ammonia(NH3)by vacancy engineering of core@shell structured Au@Sn O2 nanoparticles(NPs).We found that the ultrathin amorphous SnO2 shell with enriched oxygen vacancies was conducive to adsorb N2as well as promoted the N2 activation,meanwhile the metallic Au core ensured the good electrical conductivity for accelerating electrons transport during the electrochemical N2 reduction reaction,synergistically boosting the N2 electroreduction *** confirmed by the15N-labeling and controlled experiments,the core@shell Au@amorphous SnO2 NPs with abundant oxygen vacancies show the best performance for N2 electroreduction with the NH3 yield rate of 21.9 lg h-1mg-1catand faradaic efficiency of 15.2%at-10.2 VRHE,which surpass the Au@crystalline SnO2 NPs,individual Au NPs and all reported Au-based catalysts for ENR.