毫米波三维异质异构集成技术的进展与应用

三维异质异构集成技术是实现电子信息系统向着微型化、高效能、高整合、低功耗及低成本方向发展的最重要方法,也是决定信息化平台中微电子和微纳系统领域未来发展的一项核心高技术。文章详细介绍了毫米波频段三维异质异构集成技术的优势、近年来的发展趋势以及面临的挑战。利用硅基MEMS 光敏复合薄膜多层布线工艺可实现异质芯片的低损耗互连,同时三维集成高性能封装滤波器、高辐射效率封装天线等无源元件,还能很好地处理布线间的电磁兼容和芯片间的屏蔽问题。最后介绍了一款新型毫米波三维异质异构集成雷达及其在远距离生命体征探测方面的应用。     

基于LBSN动态异构网络的时间感知兴趣点推荐

随着基于位置社交网络(Location-Based Social Network,LBSN)的快速发展,兴趣点(Point-Of-Interest,POI)推荐可以帮助人们发现有趣的并吸引人的位置。针对签到数据的稀疏性和用户兴趣的动态性等挑战性问题,提出了基于LBSN动态异构网络的时间感知兴趣点推荐算法。在LBSN异构网络模式中增加会话节点类型。通过动态元路径,在用户和兴趣点语义关系之间有效地融入时间信息、位置信息和社交信息等。设置了用户-兴趣点之间的动态元路径集,并提出了动态路径实例的偏好度计算方法。采用矩阵分解模型对不同动态偏好矩阵进行矩阵分解。根据不同动态元路径的用户特征矩阵和兴趣点特征矩阵,获取用户在目标时间访问兴趣点的推荐列表。实验结果表明,与其他兴趣点推荐方法相比,所提方法在兴趣点推荐精确度上取得了较好的推荐结果,具有良好的应用前景。     

基于混合蚁群算法的异质车队低碳VRP研究

针对货运车辆在配送调度过程中产生大量碳排放的问题，建立模型将多种影响碳排放量的因素协同优化。模型中考虑了不同载重量的异质车队，两个节点之间有多条道路的柔性路径，以及车辆重量随卸货而减少的动态负载等因素，以碳排放量、行驶时间和行驶路程为优化目标，并加入了节点需求时间窗、根据速度变化划分路段、交接和卸货时间的约束。提出了一种混合蚁群算法，利用蚁群算法信息素强度更新方式保持群体记忆性，利用粒子群算法的快速收敛特性增加计算效率。通过随机数值算例的仿真优化与对比分析，验证了算法和模型的有效性。     

Controllability and observability of multi-agent systems with heterogeneous and switching topologies

ABSTRACT

This paper focuses on controllability and observability of multi-agent systems with heterogeneous and switching topologies, where the first- and the second-order information interaction topologies are different and switching. First, based on the controllable state set, a controllability criterion is obtained in terms of the controllability matrix corresponding to the switching sequence. Next, by virtue of the subspace sequence, two necessary and sufficient algebraic conditions are established for controllability in terms of the system matrices corresponding to all the possible topologies. Furthermore, controllability is considered from the graphic perspective. It is proved that the system is controllable if the union graph of all the possible topologies is controllable. With respect to observability, two sufficient and necessary conditions are derived by taking advantage of the system matrices and the corresponding invariant subspace, respectively. Finally, some simulation examples are worked out to illustrate the theoretical results.     

Differential graphical games for H∞ control of linear heterogeneous multiagent systems

Differential graphical games have been introduced in the literature to solve state synchronization problem for linear homogeneous agents. When the agents are heterogeneous, the previous notion of graphical games cannot be used anymore and a new definition is required. In this paper, we define a novel concept of differential graphical games for linear heterogeneous agents subject to external unmodeled disturbances, which contain the previously introduced graphical game for homogeneous agents as a special case. Using our new formulation, we can solve both the output regulation and H_∞ output regulation problems. Our graphical game framework yields coupled Hamilton‐Jacobi‐Bellman equations, which are, in general, impossible to solve analytically. Therefore, we propose a new actor‐critic algorithm to solve these coupled equations numerically in real time. Moreover, we find an explicit upper bound for the overall ‐gain of the output synchronization error with respect to disturbance. We demonstrate our developments by a simulation example.     

Highly Thermotolerant Metal Halide Perovskite Solids

By virtue of their narrow emission bands, near-unity quantum yield, and low fabrication cost, metal halide perovskites hold great promise in numerous aspects of optoelectronic applications, including solid-state lighting, lasing, and displays. Despite such promise, the poor temperature tolerance and suboptimal quantum yield of the existing metal halide perovskites in their solid state have severely limited their practical applications. Here, a straightforward heterogeneous interfacial method to develop superior thermotolerant and highly emissive solid-state metal halide perovskites is reported and their use as long-lasting high-temperature and high-input-power durable solid-state light-emitting diodes is illustrated. It is found that the resultant materials can well maintain their superior quantum efficiency after heating at a temperature over 150 °C for up to 22 h. A white light-emitting diode (w-LED) constructed from the metal halide perovskite solid exhibits superior temperature sustainable lifetime over 1100 h. The w-LED also displays a highly durable high-power-driving capability, and its working current can go up to 300 mA. It is believed that such highly thermotolerant metal halide perovskites will unleash the possibility of a wide variety of high-power and high-temperature solid-state lighting, lasing, and display devices that have been limited by existing methods.     

Highly Stable COF‐Supported Co/Co(OH)2 Nanoparticles Heterogeneous Catalyst for Reduction of Nitrile/Nitro Compounds under Mild Conditions

Ordered nanoporosity in covalent organic framework (COF) offers excellent opportunity for property development. Loading nanoparticles (nPs) onto them is one approach to introducing tailor‐made properties into a COF. Here, a COF–Co/Co(OH)₂ composite containing about 16 wt% of <6 nm sized Co/Co(OH)₂ nPs is prepared on a N‐rich COF support that catalyzes the release of theoretical equivalence of H₂ from readily available, safe, and cheap NaBH₄. Furthermore, the released H₂ is utilized for the hydrogenation of nitrile and nitro compounds to amines under ambient conditions in a facile one‐pot reaction. The COF “by choice” is built from “methoxy” functionalized dialdehydes which is crucial in enabling the complete retention of the COF structure under the conditions of the catalysis, where the regular Schiff bonds would have hydrolyzed. The N‐rich binding pockets in the COF ensure strong nP–COF interactions, which provides stability and enables catalyst recycling. Modeling studies reveal the crucial role played by the COF in exposing the active facets and thereby in controlling the activation of the reducing agent. Additionally, via density functional theory, we provide a rational explanation for how these COFs can stabilize nanoparticles which grow beyond the limiting pore size of the COF and yet result in a truly stable heterogeneous catalyst – a ubiquitous observation. The study underscores the versatility of COF as a heterogeneous support for developing cheap and highly active nonnoble metal catalysts.     

Heterogeneous Bimetallic Mo-NiPx/NiSy as a Highly Efficient Electrocatalyst for Robust Overall Water Splitting

Highly efficient electrocatalysts composed of earth-abundant elements are desired for water-splitting to produce clean and renewable chemical fuel. Herein, a heteroatomic-doped multi-phase Mo-doped nickel phosphide/nickel sulfide (Mo-NiP_x/NiS_y) nanowire electrocatalyst is designed by a successive phosphorization and sulfuration method for boosting overall water splitting (both oxygen and hydrogen evolution reactions (HER)) in alkaline solution. As expected, the Mo-NiP_x/NiS_y electrode possesses low overpotentials both at low and high current densities in HER, while the Mo-NiP_x/NiS_y heterostructure exhibits high active performance with ultra-low overpotentials of 137, 182, and 250 mV at the current density of 10, 100, and 400 mA cm⁻² in 1 m KOH solution, respectively, in oxygen evolution reaction. In particular, the as-prepared Mo-NiP_x/NiS_y electrodes exhibit remarkable full water splitting performance at both low and high current densities of 10, 100, and 400 mA cm⁻² with 1.42, 1.70, and 2.36 V, respectively, which is comparable to commercial electrolysis.     

初创型团队异质性与团队创新的关系:基于团队外部知识网络的视角

目的探索基于团队外部知识网络视角来考察年龄异质性和专业异质性对初创型异质性团队创新的作用。方法采用问卷调查的方法。对102个初创型团队进行调查。结果在初创型团队中,年龄异质性和专业异质性均能提升团队创新,外部知识网络利用强度和广度在年龄异质性促进团队创新的过程中承担中介作用,外部知识网络利用强度在专业异质性促进团队创新的过程中承担中介作用。结论在初创型团队中,年龄异质性通过提升外部知识网络利用促进团队创新,专业异质性通过提升外部知识网络利用强度促进团队创新。     

Unrelated toxin–antitoxin systems cooperate to induce persistence

Persisters are drug-tolerant bacteria that account for the majority of bacterial infections. They are not mutants, rather, they are slow-growing cells in an otherwise normally growing population. It is known that the frequency of persisters in a population is correlated with the number of toxin–antitoxin systems in the organism. Our previous work provided a mechanistic link between the two by showing how multiple toxin–antitoxin systems, which are present in nearly all bacteria, can cooperate to induce bistable toxin concentrations that result in a heterogeneous population of slow- and fast-growing cells. As such, the slow-growing persisters are a bet-hedging subpopulation maintained under normal conditions. For technical reasons, the model assumed that the kinetic parameters of the various toxin–antitoxin systems in the cell are identical, but experimental data indicate that they differ, sometimes dramatically. Thus, a critical question remains: whether toxin–antitoxin systems from the diverse families, often found together in a cell, with significantly different kinetics, can cooperate in a similar manner. Here, we characterize the interaction of toxin–antitoxin systems from many families that are unrelated and kinetically diverse, and identify the essential determinant for their cooperation. The generic architecture of toxin–antitoxin systems provides the potential for bistability, and our results show that even when they do not exhibit bistability alone, unrelated systems can be coupled by the growth rate to create a strongly bistable, hysteretic switch between normal (fast-growing) and persistent (slow-growing) states. Different combinations of kinetic parameters can produce similar toxic switching thresholds, and the proximity of the thresholds is the primary determinant of bistability. Stochastic fluctuations can spontaneously switch all of the toxin–antitoxin systems in a cell at once. The spontaneous switch creates a heterogeneous population of growing and non-growing cells, typical of persisters, that exist under normal conditions, rather than only as an induced response. The frequency of persisters in the population can be tuned for a particular environmental niche by mixing and matching unrelated systems via mutation, horizontal gene transfer and selection.