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Numerical Analysis of PRISM-PY Calculations for Hard-and Soft-Core Generic Polymer Models

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Chinese Journal of Polymer Science 2024年第4期42卷 532-543页

作者： qiang wang Department of Chemical and Biological Engineering Colorado State University1370 Campus DeliveryFort CollinsCO80523-1370USA

Generic polymer models capturing the chain connectivity and excluded-volume interactions between polymer segments can be classified, according to whether or not the 3D integral of the latter diverges, into hard- and soft-core models. Taking homogeneous systems of compressible homopolymer melts (or equivalently homopolymer solutions in an implicit, good solvent) in the continuum as an example, we recently compared the correlation effects on the structural and thermodynamic properties of the hard- and soft-core models given by the polymer reference interaction site model (PRISM) theory with the Percus-Yevick (PY) closure (Polymers 2023, 15, 1180). Here we analyzed in detail the numerical errors and behavior of the interchain pair correlation functions (PCFs) given by the PRISM-PY calculations of these models using an efficient numerical approach that we proposed. Our numerical approach has the least number of independent variables to be iteratively solved, analytically treats the discontinuities caused by the non-bonded pair potential (such as that of the hard spheres) and takes only the inverse Fourier transform of the interchain indirect PCF between polymer segments (which is continuous and decays towards 0 with increasing wavenumber much faster than both the interchain direct and total PCFs), and is essential for us to accurately solve the PRISM-PY theory for chain length N as large as 106. To capture the correlation-hole effect, the real-space cut-off in the PRISM calculations should be proportional to the square root of N.

关键词： Generic polymer models Soft potentials Polymer reference interaction site model theory

基于无人机多光谱数据和氮素空间分异的玉米冠层氮浓度估算

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作物学报 2025年第1期51卷 189-206页

作者：郝琪陈天陆王富贵王振白岚方王永强王志刚内蒙古农业大学农学院内蒙古呼和浩特010010

作物冠层氮素营养的遥感诊断对指导作物精准施氮,提高作物氮效率和产量具有重要意义。本研究针对玉米冠层纵深大影响无人机估算氮浓度精度的问题,基于2022年和2023年不同氮肥运筹处理下田间无人机多光谱数据和氮浓度实测数据,分析玉米... 详细信息

作物冠层氮素营养的遥感诊断对指导作物精准施氮,提高作物氮效率和产量具有重要意义。本研究针对玉米冠层纵深大影响无人机估算氮浓度精度的问题,基于2022年和2023年不同氮肥运筹处理下田间无人机多光谱数据和氮浓度实测数据,分析玉米冠层氮浓度空间分布特征,并利用随机森林算法确定估算冠层氮浓度的有效叶层。进一步结合随机森林算法和多光谱植被指数构建有效叶层氮浓度估算模型,最终将有效叶层氮浓度转换到冠层尺度实现冠层氮浓度的估算。结果表明:(1)九叶展期和大喇叭口期玉米冠层氮浓度表现为上层叶片>中层叶片>下层叶片,吐丝期和乳熟期表现为中层叶片>上层叶片>下层叶片。(2)各时期估算冠层氮浓度的有效叶层分别为下层、中层、中层和中层。与支持向量回归模型相比,随机森林回归估算冠层氮浓度的精度较高。(3)结合随机森林算法,基于有效叶层氮浓度估算冠层氮浓度的平均RMSE、NRMSE和MAE分别为0.10%、4.41%和0.07%,而直接基于植被指数估算冠层氮浓度的平均RMSE、NRMSE和MAE分别为0.19%、9.00%和0.15%。综上,玉米冠层氮浓度存在空间分异特征,估算冠层氮浓度时考虑基于随机森林和植被指数估算的有效叶层氮浓度能明显提高冠层氮浓度的估算精度。本研究确定的考虑空间分异的冠层氮浓度估算框架可为玉米氮素营养实时诊断提供理论支撑。

关键词：玉米冠层氮浓度氮素空间分异多光谱数据机器学习

Optimal feedback gains of a delayed proportional-derivative(PD) control for balancing an inverted pendulum

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Acta Mechanica Sinica 2017年第3期33卷 635-645页

作者： qiang wang Zaihua wang Institute of Science PLA University of Science and Technology State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

In the dynamics analysis and synthesis of a controlled system, it is important to know for what feedback gains can the controlled system decay to the demanded steady state as fast as possible. This article presents a systematic method for finding the optimal feedback gains by taking the stability of an inverted pendulum system with a delayed proportional-derivative controller as an example. First, the condition for the existence and uniqueness of the stable region in the gain plane is obtained by using the D-subdivision method and the method of stability switch. Then the same procedure is used repeatedly to shrink the stable region by decreasing the real part of the rightmost characteristic root. Finally, the optimal feedback gains within the stable region that minimizes the real part of the rightmost root are expressed by an explicit formula. With the optimal feedback gains, the controlled inverted pendulum decays to its trivial equilibrium at the fastest speed when the initial values around the origin are fixed. The main results are checked by numerical simulation.

关键词： Inverted pendulum Time delay Stability Rightmost characteristic root Optimal feedback gain

Compressive sampling and reconstruction in shift-invariant spaces associated with the fractional Gabor transform

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Defence Technology（防务技术） 2022年第6期18卷 976-994页

作者： qiang wang Chen Meng Cheng wang Shijiazhuang Campus Army Engineering UniversityShijiazhuangPR China

In this paper,we propose a compressive sampling and reconstruction system based on the shift-invariant space associated with the fractional Gabor *** this system,we aim to achieve the subNyquist sampling and accurate reconstruction for chirp-like signals containing time-varying *** the proposed scheme,we introduce the fractional Gabor transform to make a stable expansion for signals in the joint time-fractional-frequency *** the compressive sampling and reconstruction system is constructed under the compressive sensing and shift-invariant space *** establish the reconstruction model and propose a block multiple response extension of sparse Bayesian learning algorithm to improve the reconstruction *** reconstruction error for the proposed system is *** show that,with considerations of noises and mismatches,the total error is *** effectiveness of the proposed system is verified by numerical *** is shown that our proposed system outperforms the other systems state-of-the-art.

关键词： Compressive sampling Reconstruction Shift-invariant space Fractional gabor transform Chirp-like signals

Non-fullerene small molecule electron acceptors for high-performance organic solar cells

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Journal of Energy Chemistry 2018年第4期27卷 990-1016页

作者： Hao Lin qiang wang Key Laboratory of Applied Surface and Colloid Chemistry National Ministry of Education Shaanxi Key Laboratory for Advanced Energy Devices Shaanxi Engineering Lab for Advanced Energy Technology School of Materials Science and Engineering Shaanxi Normal University

Fullerenes and their derivatives are important types of electron acceptor materials and play a vital role in organic solar cell devices. However, the fullerene acceptor material has some difficulties to overcome the intrinsic shortcomings, such as weak absorption in the visible range, difficulty in modification and high cost, which limit the performance of the device and the large-scale application of this type of acceptors. In recent years, non-fullerene electron acceptor material has attracted the attention of scientists due to the advantages of adjustable energy level, wide absorption, simple synthesis, low processing cost and good solubility. Researchers can use the rich chemical means to design and synthesize organic small molecules and their oligomers with specific aggregation morphology and excellent optoelectronic prop- erties. Great advances in the field of synthesis, device engineering, and device physics of non-fullerene acceptors have been achieved in the last few years. At present, non-fullerene small molecules based photovoltaic devices achieve the highest efficiency more than 13% and the efficiency gap between fullerenetype and non-fullerene-type photovoltaic devices is gradually narrowing. In this review, we explore recent progress of non-fullerene small molecule electron acceptors that have been developed and led to highefficiency photovoltaic devices and put forward the prospect of development in the future.

关键词： Organic solar cells Non-fullerene Electron acceptors Bulk heterojunction

Cluster synchronization of a class of multi-agent systems with a bipartite graph topology

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Science China(Information Sciences) 2014年第1期57卷 192-202页

作者： wang qiang wang YuZhen School of Control Science and Engineering Shandong University

This paper investigates cluster synchronization of a class of multi-agent systems with a directed bipartite graph topology,and presents a number of new results by using the neighbor’s rules for the following two cases:I)there is competition among the agents of diferent clusters,and II)there are both competition and cooperation among the ***,for case I),a linear control protocol is designed for cluster synchronization of multi-agent systems,and a method is presented to determine the final state with the initial conditions based on state-space ***,we study case II),and design a control protocol based on the information of neighbors and that of two-hop neighbors(that is,neighbors’neighbors).Finally,two examples are studied by using our presented *** study of illustrative examples with simulations shows that our results as well as designed control protocols work very well in studying the cluster synchronization of this class of multi-agent systems.

关键词： multi-agent systems bipartite graph clustering synchronization competition cooperation state-space decomposition.

An Algorithm for Labeling Stable Regions of a Class of Time-Delay Systems with Abscissa

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第1期35卷 94-100页

作者： wang qiang wang Zaihua Army Engineering University of PLA Nanjing 211101P.R.China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

Stability is usually in the sense of Lyapunov′s asymptotical stability,thus the solutions starting from points close to a stable equilibrium may have a very long *** the applications of time-delayed feedback controls,it is important not only to determine the stable regions in the gain plane or gain space,but also to find out the abscissa that can be used as an index of *** on the D-subdivision method,this paper proposes a simple algorithm for finding and labeling the stable regions in feedback gain plane with *** labeled sub-regions with smaller abscissa are better in *** main results are presented for the controlled pendulum or inverted pendulum under a delayed feedback,and are illustrated with two case studies.

关键词： time delay stability Lyapunov′s stability abscissa delayed feedback optimal feedback gain

Optimization of the Drag Forces of Shell Janus Micromotor:A Study Based on Hydrodynamical Analysis and Numerical Simulation

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Computer Modeling in Engineering & Sciences 2022年第1期130卷 443-462页

作者： qiang wang Zhen wang Wuhan University of Technology Wuhan430070China

Micromotors are widely used in cell operation,drug delivery and environmental decontamination due to their small size,low energy consumption and large propelling *** to traditional Janus micromotor,the shell Janusmicromotor has better motion ***,the structural optimization of itsmotion performance is still *** main factor restricting the motion performance of shell Janus micromotors is the drag *** the current work,theoretical analysis and numerical simulation were applied to analyze the drag forces of shell Janus *** study aims to design the optimum structure of shell Janus micromotors with minimum drag forces and obtain the magnitude of drag forces considering both the internal and external fluids of the shell Janus ***,the influence of the motor geometry and Reynolds number on the drag coefficient was analyzed using numerical *** results provide guidance for the optimum flow velocity,opening diameter and shell thickness to achieve minimum drag force.

关键词： Shell janus micromotor drag force dimensionless numbers

The Formation Control of Multi-agent Systems on a Circle

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IEEE/CAA Journal of Automatica Sinica 2018年第1期5卷 148-154页

作者： qiang wang Yuzhen wang Huaxiang Zhang School of Information Science and Engineering Shandong Normal University School of Control Science and Engineering Shandong University

This paper investigates the formation control of a class of multi-agent systems moving on a circle, whose topology is a cyclic graph, and presents several new results for the following two cases: Case I, the agents with single-integrator kinematics,and Case II, the agents with double-integrator kinematics. Firstly,for Case I, two control protocols are proposed under which the multiagent systems keep a uniformly-spaced formation. Secondly,we study Case II, and a control protocol is designed for this case, then the stability of the formation is proved. Finally, three simulations are studied by using our presented results. The study of illustrative examples with simulations shows that our results as well as designed control protocols work very well in studying the formation control of this class of multi-agent systems.

关键词： Circle cyclic graph formation control multiagent systems uniformly spaced