挥发性有机物形成光化学烟雾的分子机理

大气污染是人类无法逃避、日趋严重的环境问题,威胁着亿万民众的健康和生活环境。从分子水平上理解大气二次污染物形成机理是预防、控制和治理大气污染的重要基础。在这方面,基于电子结构计算和动力学模拟的理论研究有其独特的优势。由于机理过程涉及光诱导的超快反应,如何开展多尺度计算模拟,目前还面临诸多挑战。在拟开展的工作中,我们将发展和应用高精度的量子化学计算方法、非绝热的速率和动力学理论;建立适合大气复杂环境的量子力学和分子力学组合的计算模型;研究系列挥发性有机物形成光化学烟雾的分子机理,发现并解决光化学烟雾形成过程中的一些重要的关键基础科学问题,为预防、控制和治理大气光化学污染提供理论依据和有意义的指导。     

低标度量子化学计算软件

当前化学及相关学科对复杂体系(包括大分子和凝聚相体系等)的研究越来越广泛,实验与定量计算的需求要求量子化学能够处理越来越复杂的体系,因此低标度量子化学计算软件成为计算化学软件发展的重要热点之一。本文围绕该主题,在国家自然科学基金委员会第181期双清论坛研讨成果的基础上,结合国家重大需求和理论化学学科发展前沿,针对复杂体系的量子化学算法,回顾了当前国内外低标度量子化学计算软件的进展与不足,提炼了在低标度量子化学算法和软件发展领域面临的挑战,给出了在未来5—10年该领域需要重点发展的方向建议。     

大规模原子模拟软件包(LSASP)程序设计和进展

本文介绍了笔者课题组开发的针对复杂体系精确计算的软件包LSASP,包括核心算法,软件架构以及开发进展。与传统经验力场的程序不同,LSASP软件整合现有的通用电子结构计算软件,提供统一数据接口,以通用型全局势能面神经网络势函数作为主要势能面计算工具,涵盖全局结构搜索,自动反应路径取样,过渡态寻找,分子动力学,蒙特卡洛模拟等势能面采样功能的大尺度计算平台。LSASP软件的核心算法,随机势能面行走(SSW),具有自有知识产权,在势能面全局搜索,过渡态反应路径搜索,神经网络势函数模拟等方面具有国际竞争力。     

材料的理性设计与计算模拟

材料的理性设计与计算模拟是基于计算机开展的"实验"研究。通过材料的理性设计与计算模拟,可以在原子层次上揭示材料的结构与性能之间的联系,预测新材料。这也促进了材料科学研究模式从"经验指导实验"向"理性设计与计算模拟、实验验证"转变。材料的理性设计与计算模拟的核心问题是发展先进的电子结构计算方法与软件,包括可以处理复杂材料体系的快速、可靠的方法与软件,以及材料"大数据"驱动的材料理性设计。     

基于有限元方法计算飞机结构连接的细节载荷

分析了飞机紧固件典型的连接方式,考虑了紧固件的承载方式,选择合适的单元来模拟紧固件,同时对选取的单元进行修正,建立了连接件端部紧固件有限元模型,求解算例并与理论方法作对比。结果表明:使用有限元法计算的结果与理论计算结果差别很小,使用有限元法计算连接件紧固件载荷分布是可行的,精度满足工程要求,解析法可以得到较为精确紧固件载荷,但是只能计算简单规则连接件,有限元法通过对结构合理简化和修正单元属性,可以准确计算复杂结构的紧固件载荷。     

新一代高精度生物大分子力场

精确地描述分子内和分子间相互作用是生物分子体系动力学计算和模拟的核心问题。势能面的精确度直接影响并决定了整个计算结果的可靠性和预言的准确性。因此,发展和应用精确势能面是生命科学计算中最至关重要的一个环节。可以预言,未来生命科学定量计算的发展途径仍然会与开发新一代更精确的生物分子势能面紧密相关。本文通过经典分子力场发展过程和现状为借鉴,探讨未来分子力场发展的可能趋势。     

多尺度理论模拟助力解决金属酶催化机理核心问题 ——厦门大学王斌举教授

多尺度理论模拟方法包括量子化学计算、分子动力学模拟、量子力学-分子力学组合方法,以及从头算动力学模拟.多年来,厦门大学王斌举教授一直从事溶液和蛋白质环境中化学反应过程的多尺度模拟相关工作,在水介质中化学反应的理论研究,多尺度方法研究金属酶的电子结构、催化机理与活性调控、氧化还原酶中的活性氧物种以及金属酶介导的电子转移机制等方面具有良好的工作积累,取得了一系列具有影响力的科研成果.     

国内计算化学方法与软件开发

当前理论与计算化学正处于蓬勃发展时期,其中计算方法和软件的开发具有基础性地推动作用,类似实验科学中的先进科学仪器的创制。近年来,我国已有几十个研究小组在电子结构计算、动力学模拟、分子力场、药物设计、材料结构与性质预测等领域开发了各种新的计算方法,其中有些已经达到国际先进水平,且很多都有较高的实际应用价值。另一方面,很多研究工作仍然依赖国外的计算软件作为基础或平台,开发具有自主知识产权的计算化学软件平台将提升这些国内新方法的影响力并促进它们的广泛应用。     

化学反应动力学

氟原子加氢分子及其同位素分子的反应(F+H2/D2/HD)在化学反应动力学的研究发展中一直扮演着重要的角色。在过去的10年里,科学家们通过精心设计的实验和高精度的理论计算,使得有关该反应体系的态-态动力学研究,特别是对反应机制、过渡态结构及其动力学性质、非绝热效应的认识有了长足的进步,得到了有关F+H2这个教科书式的反应体系动力学行为的结论性的研究成果。     

标准模型流场数值计算

本项目采用沈阳空气动力研究所研发的航空并行CFD计算平台,进行标准明星并行评估计算。该软件可广泛应用于飞行器的亚、跨、超和高超音速的气动力学计算和一些特殊气体动力学问题如直升机旋翼、导弹发射、座舱弹射、投弹、机动和气动弹性等。传统的飞行器气动布局设计主要依赖理论研究估算、设计师的经验以及大量的风洞试验结果,风洞试验是主要设计工具。计算机技术的迅猛发展推动了航空空气动力学的革命。目前正在大力发展的计算流体力学将以突破对黏流流场物理现象的模拟能力为重点,尤其是精确预测流动分离点和转捩过程以及湍流流动。随着中国航天航空事业的快速发展,尤其是载人航天技术的巨大成功,我国科技人员对空气动力学的数值模拟研究提出了越来越多的需求,常规的计算能力远远无法满足复杂的大型飞行器设计所带来的巨大需求。     

Q-learning solution for optimal consensus control of discrete-time multiagent systems using reinforcement learning

This paper investigates a Q-learning scheme for the optimal consensus control of discrete-time multiagent systems. The Q-learning algorithm is conducted by reinforcement learning (RL) using system data instead of system dynamics information. In the multiagent systems, the agents are interacted with each other and at least one agent can communicate with the leader directly, which is described by an algebraic graph structure. The objective is to make all the agents achieve synchronization with leader and make the performance indices reach Nash equilibrium. On one hand, the solutions of the optimal consensus control for multiagent systems are acquired by solving the coupled Hamilton–Jacobi–Bellman (HJB) equation. However, it is difficult to get analytical solutions directly of the discrete-time HJB equation. On the other hand, accurate mathematical models of most systems in real world are hard to be obtained. To overcome these difficulties, Q-learning algorithm is developed using system data rather than the accurate system model. We formulate performance index and corresponding Bellman equation of each agent i. Then, the Q-function Bellman equation is acquired on the basis of Q-function. Policy iteration is adopted to calculate the optimal control iteratively, and least square (LS) method is employed to motivate the implementation process. Stability analysis of proposed Q-learning algorithm for multiagent systems by policy iteration is given. Two simulation examples are experimented to verify the effectiveness of the proposed scheme.     

Leader-Follower finite-time consensus of multiagent systems with nonlinear dynamics by intermittent protocol

This paper deals with the leader-follower finite-time consensus problem for multiagent systems with nonlinear dynamics via intermittent protocol. The topological structure of the followers is undirected or balanced digraph. Different from most existing works concerning nonlinear dynamics (satisfies Lipschitz continuity), the nonlinear dynamics of each agent satisfies Hölder continuity in this paper. In light of the finite-time control technique, the intermittent control protocol is designed to reach accurate leader-follower finite-time consensus. It is justified that the leader-follower finite-time consensus can be realized if the length of communication is greater than a critical value by using limit theory. Finally, two numerical examples are exhibited to validate the effectiveness of the proposed scheme.     

A novel reset control approach to leader-following consensus of second-order nonlinear multi-agent systems

This paper investigates the leader-following consensus problem of second-order nonlinear multi-agent systems with directed graph. A novel reset control approach is proposed for the aim of improving transient consensus performance, e.g., settling time. By introducing consensus error into reset conditions, the output of reset integrator will keep the same sign with the consensus error, thus, the desired states can be compensated preferentially and the system transient performance is improved accordingly. To appropriately describe the closed-loop system with reset-induced jump dynamics, a hybrid system model consisting of both flow dynamics and jump dynamics is constructed. Based on this model, and combined with backstepping method, Lyapunov-based consensus analysis is presented under hybrid system framework. Finally, a numerical example is provided to show the effectiveness of the obtained results.     

东北三省区域工业结构和竞争力分析

用偏离—份额法对东北三省的工业结构和竞争力进行分解 ,然后对计算结果进行了成因分析 ,得到一些具有启发意义的结论 .认为东北三省工业发展宜首先应该找准方向 ,从改善结构和提高竞争力两方面着手 ,在根本上提升区域经济发展的能力 .     

A new approach to the modeling of distributed structures for control

Building structures represent complex distributed-parameter systems. The motion of such systems is described by partial differential equations complemented by suitable boundary conditions. For control design purposes, distributed-parameter systems must be discretized in the spatial variables. But, if the discrete model is not sufficiently accurate, controls designed on the basis of the discrete model can destabilize the actual distributed structure, in which case the controls are said to be sensitive to discretization errors. This paper presents a new approach to the discretization of distributed structures yielding accurate discrete models of relatively low order. A numerical example illustrates how controls can be designed for a complex structure subjected to earthquake excitations.     

超高压技术在化学研究中的应用

超高压技术近年来得到了快速的发展，特别是金刚石压腔装置的完善，目前已经可以达到550 GPa和6000 K的条件，使其在化学研究中具有巨大的应用前景。压力作为基本的参数，压力作用对物质的电子结构和晶体结构都存在很大的影响。超高压对电子结构的影响包括原子内和原子间，其中原子间的电荷变化包括电荷转移、不均匀分布、以及绝缘体向金属转变。物质的晶体结构在超高压作用下会发生从松散向致密的结构形式的相转变。超高压技术在有机化学反应的选择性、无机固相反应、以及气体的聚合反应等领域都具有重要的应用潜力。     

Understanding nano effects in catalysis

Catalysis, as a key and enabling technology, plays an increasingly important role in ields ranging from energy, environment and agriculture to health care. Rational design and synthesis of highly eicient catalysts has become the ultimate goal of catalysis research. hanks to the rapid development of nanoscience and nanotechnology, and in particular a theoretical understanding of the tuning of electronic structure in nanoscale systems, this element of design is becoming possible via precise control of nanoparticles' composition, morphology, structure and electronic states. At the same time, it is important to develop tools for in situ characterization of nanocatalysts under realistic reaction conditions, and for monitoring the dynamics of catalysis with high spatial, temporal and energy resolution. In this review, we discuss coninement efects in nanocatalysis, a concept that our group has put forward and developed over several years. Taking the conined catalytic systems of carbon nanotubes, metal-conined nano-oxides and 2D layered nanocatalysts as examples, we summarize and analyze the fundamental concepts, the research methods and some of the key scientiic issues involved in nanocatalysis. Moreover, we present a perspective on the challenges and opportunities in future research on nanocatalysis from the aspects of:(1) controlled synthesis of nanocatalysts and rational design of catalytically active centers;(2) in situ characterization of nanocatalysts and dynamics of catalytic processes;(3) computational chemistry with a complexity approximating that of experiments; and (4) scale-up and commercialization of nanocatalysts.     

战略性产业贸易网络的结构特征及演化模式

在经济全球化背景下,电子信息产业由于产业链绵长,片段化生产特征更为明显。现有研究主要集中于电子信息整体产业层面,缺乏对产业链视角下的电子信息产业动态和分工概念的思考。基于此,利用2006-2018年222个国家或地区的电子信息产业贸易往来数据,通过社会网络方法,探索电子信息产业上、中、下游代表性产品贸易网络的拓扑结构和主要国家的网络地位及格局演化。研究发现：电子信息产业贸易网络“核心-外围”结构明显;上游供应链网络呈现链式结构,网络密度稀疏,鲜有新的国家加入,中国在上游贸易网络中位置有所跃升,但仍未处于网络核心;中游和下游顶层网络呈现“扁平化”特征,在2006年中国已处于大部分产品贸易网络的关键节点位置,至2018年中国进一步跃升至网络核心。据此为提升中国电子信息产业在全球网络中地位,推动电子信息产业高质量发展提供有益的政策启示。     

Synthesizing antipodal chaotic waveforms

Chaotic waveforms are natural information carriers since a correspondence can be established between the symbolic dynamics of a chaotic oscillator and the symbols of a message. Message symbols can be efficiently encoded in a chaotic waveform by applying vanishingly small perturbations to an oscillator to guide its symbolic dynamics to follow a desired course. Recently, two chaotic hybrid dynamical systems were shown to have matched filters enabling robust reception of chaotic communication waveforms in the presence of noise. The first of these, the exact shift oscillator, produces waveforms with desirable properties similar to antipodal signaling, but a physical implementation may be difficult to control using small perturbations. The second oscillator, the exact folded-band oscillator, produces less optimal waveforms but is more easily controlled. Here we introduce a method for generating waveforms of the exact shift oscillator by summing waveforms from a bank of easily controlled exact folded-band oscillators. We show that any solution of the exact shift oscillator can be so constructed using only three folded-band oscillators. Thus, this scheme allows us to realize the advantages of both chaotic systems while overcoming their individual disadvantages, thereby enabling practical chaos communications.     

Containment control of heterogeneous fractional-order multi-agent systems

Fractional-order calculus has been studied deeply because many networked systems can only be described with fractional-order dynamics in complex environments. When different agents of networked systems show diverse individual features, fractional-order dynamics with heterogeneous characters will be used to illustrate the multi-agent systems (MAS). Based on the distinguishing behaviors of agents, a compounded fractional-order multi-agent systems(FOMAS) is presented with diverse dynamical equations. Suppose multiple leader agents existing in FOMAS, containment consensus control of FOMAS with directed weighted topologies is studied. By applying frequency domain analysis theory of the fractional-order operator, an upper bound of delays is obtained to ensure containment controls of heterogenous FOMAS with communication delays. The consensus results of delayed fractional-order dynamics in this paper can be expanded to the integer-order models. Finally, the results are verified by simulation examples.