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Adaptive Articulation Angle Preview-Based path-following algorithm for Tractor-Semitrailer Using Optimal Control

SENSORS 2022年第14期22卷 5163-5163页

作者： Tang, Xuequan Yan, Yunbing Wang, Baohua Zhang, Lin Wuhan Univ Sci & Technol Dept Automobile & Traff Engn 2 Huangjiahu West Rd Wuhan 430065 Peoples R China Hubei Univ Automot Technol Dept Automobile Engn Shiyan 442002 Peoples R China

Most existing path-following algorithms (PFAs) are developed for single-unit vehicles (SUVs) and rarely for articulated vehicles (AVs). Since these PFAs ignore the motion of the trailer, they may cause large tracking deviations and ride stability issues when cornering. To this end, an Adaptive Articulation Angle Preview-based path-following algorithm (AAAP-PFA) is proposed for AVs. Different from previous PFAs, in this model, a simple linear vehicle dynamics model is used as the prediction model, and an offset distance calculated by an articulation angle is used as part of the preview distance. An adaptive posture control strategy is designed to trade off the trajectory tracking performance and lateral stability performance during the path-following process. Considering a large prediction mismatch caused by using a linear vehicle dynamics model, a feedback correction method is proposed to improve the robustness of the steering control. In the comparison simulation experiment with SUV-PFA, it is confirmed that the novel PFA has better adaptability to the contradictory relationship between tracking performance and lateral stability and has strong steering control robustness.

关键词： articulated vehicles (AVs) path-following algorithm closed-loop simulation preview optimal control

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A differentiable path-following algorithm for computing perfect stationary points

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COMPUTATIONAL OPTIMIZATION AND APPLICATIONS 2020年第2期76卷 571-588页

作者： Zhan, Yang Li, Peixuan Dang, Chuangyin City Univ Hong Kong Dept Syst Engn & Engn Management Hong Kong Peoples R China

This paper is concerned with the computation of perfect stationary point, which is a strict refinement of stationary point. A differentiable homotopy method is developed for finding perfect stationary points of continuous functions on convex polytopes. We constitute an artificial problem by introducing a continuously differentiable function of an extra variable. With the optimality conditions of this problem and a fixed point argument, a differentiable homotopy mapping is constructed. As the extra variable becomes close to zero, the homotopy path naturally provides a sequence of closely approximate stationary points on perturbed polytopes, and converges to a perfect stationary point on the original polytope. Numerical experiments are implemented to further illustrate the effectiveness of our method.

关键词： Stationary point Perfectness Homotopy method path-following algorithm

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An improved phase-coding method for absolute phase retrieval based on the path-following algorithm

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OPTICS AND LASERS IN ENGINEERING 2019年 122卷 65-73页

作者： Lv, Shenzhen Sun, Qiang Yang, Jianbai Jiang, Yang Qu, Feng Wang, Jian Chinese Acad Sci R&D Ctr Precis Instruments & Equipment Changchun Inst Opt Fine Mech & Phys 3888 Dongnanhu Rd Changchun Jilin Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

Although the traditional phase-coding method for absolute phase retrieval possesses strong robustness, the method leads to unwrapping artifacts as a mass of codewords required. To solve this problem, a novel improved method is proposed in this paper. The incorrect points in the recovered phase via the traditional method are located using a computational framework, and the path-following algorithm is adopted as an aid to correct the unwrapping artifacts. The effectiveness of the proposed method is experimentally verified by an established measurement system. The reconstructed geometry of standard sphere has sufficient accuracy and the absolute phase retrieval of a complex star object has high quality.

关键词： Phase unwrapping 3D shape measurement Unwrapping artifact path-following algorithm

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A New Second-Order Infeasible Primal-Dual path-following algorithm for Symmetric Optimization

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NUMERICAL FUNCTIONAL ANALYSIS AND OPTIMIZATION 2016年第4期37卷 499-519页

作者： Yang, Ximei Zhang, Yinkui Liu, Hongwei Shen, Peiping Henan Normal Univ Coll Math & Informat Sci Xinxiang 453007 Peoples R China Xidian Univ Sch Math & Stat Xian Peoples R China

In this article, we propose a new second-order infeasible primal-dual path-following algorithm for symmetric cone optimization. The algorithm further improves the complexity bound of a wide infeasible primal-dual path-following algorithm. The theory of Euclidean Jordan algebras is used to carry out our analysis. The convergence is shown for a commutative class of search directions. In particular, the complexity bound is ?(r(5/4)logE(-1)) for the Nesterov-Todd direction, and ?(r(7/4)logE(-1)) for the xs and sx directions, where r is the rank of the associated Euclidean Jordan algebra and E is the required precision. If the starting point is strictly feasible, then the corresponding bounds can be reduced by a factor of r(3/4). Some preliminary numerical results are provided as well.

关键词： Euclidean Jordan algebra infeasible path-following algorithm second-order corrector symmetric cone optimization 90C05 90C51

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Toughening effects of out-of-crack-path architected zones

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INTERNATIONAL JOURNAL OF FRACTURE 2024年第1-3期248卷 237-255页

作者： Triclot, Julie Corre, Thomas Gravouil, Anthony Lazarus, Veronique INSA Lyon CNRS LaMCoS UMR5259 F-69621 Villeurbanne France Inst Polytech Paris IMSIA ENSTA Paris CNRSEDFCEA 828 bd Marechaux F-91762 Palaiseau France Nantes Univ Ecole Cent Nantes CNRS GeMUMR 6183 F-44000 Nantes France

The increasing use of architected materials has broadened the possibilities of mechanical behaviour. In this article, we aim to explore these new possibilities in terms of in-service behaviour, especially in terms of crack propagation by performing an in-depth study in the framework of Linear Elastic Fracture Mechanics (LEFM). The specific configuration studied here is the case where the architected zones are symmetrically positioned adjacently to the crack path and no propagation occurs within the zone. This problem is addressed both numerically and experimentally. Numerically, an path-following algorithm is used to simulate the crack propagation. Different toughening aspects of the addition of architected zones are identified. First, a temporary increase in crack propagation resistance is shown. It comes from a temporary increase of stored elastic energy in the architected zones, thus acting as mechanical springs. Second, a snap-back instability appears, linked to the release of the previously stored energy. It leads to a higher energy dissipated by the crack propagation process. Experimentally, we evidence the possibility to reproduce the theoretical results using 3D printing. A good quantitative comparison is obtained between numerical and experimental approaches. This study shows that it is possible to improve crack propagation resistance while lightening the component by addition of architected zones outside the crack path. This opens up the way to tune finely, through the use of optimization tools, the crack propagation response.

关键词： Crack propagation Architected material Snap-back instability Toughening mechanism path-following algorithm

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Rate-Splitting Multiple Access in Cell-Free Massive MIMO-URLLC Systems: Achievable Rate Analysis and Optimization

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IEEE TRANSACTIONS ON COMMUNICATIONS 2024年第11期72卷 6752-6767页

作者： Zhang, Yao Zhao, Haitao Mao, Yijie Xia, Wenchao Lu, Weidang Zhu, Hongbo Hangzhou Dianzi Univ Sch Commun Engn Hangzhou 310018 Peoples R China Hangzhou Dianzi Univ Lishui Inst Lishui 323050 Peoples R China Nanjing Univ Posts & Telecommun Dept Wireless Commun Key Lab Jiangsu Prov Nanjing 210003 Peoples R China ShanghaiTech Univ Sch Informat Sci & Technol Shanghai 201210 Peoples R China Zhejiang Univ Technol Coll Informat Engn Hangzhou 310023 Peoples R China

Rate-splitting multiple access (RSMA) has emerged as a potent paradigm shift in wireless communications, demonstrating resilience to channel state information (CSI) inaccuracies and significant rate enhancements. This work investigates RSMA's application within the context of ultra-reliable and low-latency communication (URLLC) for the forthcoming Internet-of-Everything networks. Specifically, we integrate RSMA with a cell-free massive multiple-input multiple-output (MIMO) architecture to support URLLC demands. Considering the imperfect CSI, attributable to pilot contamination and thermal noise, we derive rigorous lower-bound expressions for the downlink achievable rates. These expressions are applicable to short-packet communication scenarios and RSMA strategy over spatially correlated Rician fading channels. Utilizing these analytical expressions, we perform an exhaustive rate performance evaluation, varying system parameters such as the numbers of pilots, access points (APs), devices, and antennas per AP, alongside different multiple access techniques. Furthermore, we address the power control coefficient design for both common and private streams, framing it as an optimization problem aimed at maximizing the weighted sum-rate and enhancing URLLC service quality. To tackle this non-convex challenge, we introduce a geometric programming-based path-following algorithm, which iteratively converges to the solution. The theoretical underpinnings and the efficacy of the proposed power optimization algorithm are corroborated through extensive simulation results.

关键词： Rate-splitting multiple access (RSMA) cell-free massive multiple-input multiple-output (MIMO) ultra-reliable and low-latency communication (URLLC) weighted sum-rate (WSR) maximization path-following algorithm Rate-splitting multiple access (RSMA) cell-free massive multiple-input multiple-output (MIMO) ultra-reliable and low-latency communication (URLLC) weighted sum-rate (WSR) maximization path-following algorithm

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An arc-length control technique for solving quasi-static fracture problems with phase field models and a staggered scheme

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COMPUTATIONAL MECHANICS 2024年第4期73卷 751-772页

作者： Zambrano, J. Toro, S. Sanchez, P. J. Duda, F. P. Mendez, C. G. Huespe, A. E. Consejo Nacl Invest Cient & Tecn UNL CIMEC Predio Conicet Dr Alberto Cassano RA-3000 Santa Fe Argentina GIMNI UTN FRSF Lavaise 610 RA-3000 Santa Fe Argentina Univ Fed Rio de Janeiro COPPE Programa Engn Mecan Cidade Univ BR-21945970 Rio De Janeiro RJ Brazil

This paper describes a new arc-length control procedure for tracing the equilibrium curve of brittle fracture problems modeled with a phase field approach. The balance equations of this model are solved with a staggered strategy. The control equation of the arc-length procedure determines the displacement increments during the mechanical stage. The arc-length parameter is interpreted as imposing a given increment of the driving force appearing into the micro-force balance equation. The innovative technique consisting of applying the control equation to the displacement degrees of freedoms (DOFs) of the mechanical stage offers an enhancement over earlier arc-length strategies that focused on controlling the damage DOFs in the micro-force balance equation stage. This advancement enables the phase field approach to handle and simulate a broader range of problems, as demonstrated in this paper. The arc-length parameter is stepwise adjusted to yield a pre-established maximum damage increment in each staggered scheme step. As a consequence, the crack tip advance can be strictly controlled in every step holding bounded the pseudo-time integration error, even using an explicit staggered strategy. This procedure entails moderate computational costs for tracing the complete equilibrium curve, including unstable responses, limit points, snap-backs, etc., with the subsidiary advantage that lack of convergence has never been detected in the tests presented in this paper. Additionally, line search techniques have not been necessary. The proposed arc-length procedure is easily implemented in standard finite element codes, and according to our numerical experiments, it does not significantly increase the computational burden of the original explicit staggered strategy.

关键词： Arc-length control strategy Phase field models Staggered methodology path-following algorithm Quasi-static brittle fracture Unstable crack growth

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An Interior-Point Differentiable path-following Method to Compute Stationary Equilibria in Stochastic Games

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INFORMS JOURNAL ON COMPUTING 2022年第3期34卷 1403-1418页

作者： Dang, Chuangyin Herings, P. Jean-Jacques Li, Peixuan City Univ Hong Kong Dept Syst Engn & Engn Management Kowloon Hong Kong Peoples R China Maastricht Univ Dept Econ NL-6200 MD Maastricht Netherlands

The subgame perfect equilibrium in stationary strategies (SSPE) is the most important solution concept in applications of stochastic games, making it imperative to develop efficient methods to compute an SSPE. For this purpose, this paper develops an interior-point differentiable path-following method (IPM), which establishes a connection between an artificial logarithmic barrier game and the stochastic game of interest by adding a homotopy variable. IPM brings several advantages over the existing methods for stochastic games. On the one hand, IPM provides a bridge between differentiable path-following methods and interior-point methods and remedies several issues of an existing homotopy method called the stochastic linear tracing procedure (SLTP). First, the starting stationary strategy profile can be arbitrarily chosen. Second, IPM does not need switching between different systems of equations. Third, the use of a perturbation term makes IPM applicable to all stochastic games rather than generic games only. Moreover, a well-chosen transformation of variables reduces the number of equations and variables by roughly one half. Numerical results show that the proposed method is more than three times as efficient as SLTP. On the other hand, the stochastic game can be reformulated as a mixed complementarity problem and solved by the path solver. We employ the proposed IPM and the path solver to compute SSPEs. Numerical results evince that for some stochastic games the path solver may fail to find an SSPE, whereas IPM is successful in doing so for all stochastic games, which confirms the reliability and stability of the proposedmethod.

关键词： stochastic games subgame perfect equilibria stationary strategies interior-point method path-following algorithm

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Secure RSMA for CF-mMIMO Systems With Low-Resolution DACs

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IEEE WIRELESS COMMUNICATIONS LETTERS 2024年第6期13卷 1660-1664页

作者： Zhang, Yao Yang, Kaixi Xia, Wenchao Zhang, Jun Ni, Yiyang Lu, Weidang Hangzhou Dianzi Univ Sch Commun Engn Hangzhou 310018 Peoples R China Zhejiang Normal Univ Coll Phys & Elect Informat Engn Jinhua 321004 Peoples R China Nanjing Univ Posts & Telecommun Dept Wireless Commun Key Lab Jiangsu Prov Nanjing 210003 Peoples R China Zhejiang Univ Technol Coll Informat Engn Hangzhou 310023 Peoples R China

This letter presents an investigation into secure transmission in a downlink rate-splitting-aided cell-free massive multiple-input multiple-output system. By incorporating the low-resolution digital-to-analog converters and imperfect channel knowledge, we derive tight closed-form expressions for the data rate and secrecy rate under Ricean fading channels. Additionally, we formulate a power control problem with the objective of maximizing the weighted sum data rate, while ensuring a target secrecy rate for all user equipments. A path-following optimization algorithm is then proposed to determine its solution numerically. All theoretical analyses and the efficacy of the proposed algorithm are validated through extensive simulations.

关键词： Rate-splitting multiple access cell-free massive multiple-input multiple-output low-resolution digital-to-analog converters secure transmission path-following algorithm

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Efficient Active Learning by Querying Discriminative and Representative Samples and Fully Exploiting Unlabeled Data

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IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS 2021年第9期32卷 4111-4122页

作者： Gu, Bin Zhai, Zhou Deng, Cheng Huang, Heng Nanjing Univ Informat Sci & Technol Jiangsu Engn Ctr Network Monitoring Nanjing 210044 Peoples R China Nanjing Univ Informat Sci & Technol Sch Comp & Software Nanjing 210044 Peoples R China JD Finance Amer Corp Mountain View CA 94043 USA Xidian Univ Sch Elect Engn Xian 710114 Peoples R China Univ Pittsburgh Dept Elect & Comp Engn Pittsburgh PA 15260 USA

Active learning is an important learning paradigm in machine learning and data mining, which aims to train effective classifiers with as few labeled samples as possible. Querying discriminative (informative) and representative samples are the state-of-the-art approach for active learning. Fully utilizing a large amount of unlabeled data provides a second chance to improve the performance of active learning. Although there have been several active learning methods proposed by combining with semisupervised learning, fast active learning with fully exploiting unlabeled data and querying discriminative and representative samples is still an open question. To overcome this challenging issue, in this article, we propose a new efficient batch mode active learning algorithm. Specifically, we first provide an active learning risk bound by fully considering the unlabeled samples in characterizing the informativeness and representativeness. Based on the risk bound, we derive a new objective function for batch mode active learning. After that, we propose a wrapper algorithm to solve the objective function, which essentially trains a semisupervised classifier and selects discriminative and representative samples alternately. Especially, to avoid retraining the semisupervised classifier from scratch after each query, we design two unique procedures based on the path-following technique, which can remove multiple queried samples from the unlabeled data set and add the queried samples into the labeled data set efficiently. Extensive experimental results on a variety of benchmark data sets not only show that our algorithm has a better generalization performance than the state-of-the-art active learning approaches but also show its significant efficiency.

关键词： Active learning maximum mean discrepancy (MMD) path-following algorithm semisupervised support vector machine

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