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Reconfigurable Intelligent Surface-Assisted Non-Orthogonal Multiple Access

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2021年第5期20卷 3137-3151页

作者： Yang, Gang Xu, Xinyue Liang, Ying-Chang Di Renzo, Marco Univ Elect Sci & Technol China UESTC Natl Key Lab Sci & Technol Commun Chengdu 611731 Peoples R China Univ Elect Sci & Technol China UESTC Ctr Intelligent Networking & Commun CINC Chengdu 611731 Peoples R China Univ Paris Saclay Lab Signaux & Syst Cent Supelec CNRS F-91192 Gif Sur Yvette France

Reconfigurable intelligent surface (RIS) is a revolutionary technology to achieve spectrum-, energy-, and cost-efficient wireless networks. This paper considers an RIS-assisted downlink non-orthogonal-multiple-access (NOMA) system. To optimize the rate performance and ensure user fairness, we maximize the minimum decoding signal-to-interference-plus-noise-ratio (equivalently the rate) of all users, by jointly optimizing the (active) transmit beamforming at the base station (BS) and the phase shifts (i.e., passive beamforming) at the RIS. A combined-channel-strength based user-ordering scheme for NOMA decoding is first proposed to decouple the user-ordering design and the joint beamforming design. Efficient algorithms are further proposed to solve the non-convex problem, by leveraging the block coordinated descent and semidefinite relaxation (SDR) techniques. For the single-antenna BS setup, the optimal power allocation at the BS and the asymptotically optimal phase shifts at the RIS are obtained in closed forms. For the multiple-antenna BS setup, it is shown that the rank of the SDR solution of the transmit beamforming design is upper bounded by two. Also, the proposed algorithms are analyzed in terms of convergence and complexity. Simulation results show that the RIS-assisted NOMA system can enhance the rate performance significantly, compared to traditional NOMA without RIS and traditional orthogonal multiple access with/without RIS.

关键词： NOMA Array signal processing Downlink Wireless communication Resource management MISO communication Decoding Non-orthogonal multiple access reconfigurable intelligent surface rate optimization user fairness iterative algorithm

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Trajectory design and resource allocation for UAV energy minimization in a rotary-wing UAV-enabled WPCN

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ALEXANDRIA ENGINEERING JOURNAL 2021年第1期60卷 1787-1796页

作者： Wang, Zhen Wen, Miaowen Dang, Shuping Yu, Lisu Wang, Yuhao Beijing Univ Posts & Telecommun Sch Informat & Commun Engn Beijing 100876 Peoples R China Nanchang Univ Sch Informat Engn Nanchang 330031 Jiangxi Peoples R China South China Univ Technol Sch Elect & Informat Engn Guangzhou 510641 Peoples R China King Abdullah Univ Sci & Technol KAUST Comp Elect & Math Sci & Engn Div Thuwal 239556900 Saudi Arabia Chinese Acad Sci Inst Comp Technol State Key Lab Comp Architecture Beijing 100190 Peoples R China

Due to the low efficiency of energy harvest (EH) for the traditional wireless powered communication network (WPCN), we propose a communication scheme based on unmanned aerial vehicle (UAV)-enabled WPCN, which can greatly improve the EH efficiency problem. In this paper, the UAV trajectory, time allocation, transmit power of UAVs, scheduling of wireless information transfer (WIT) and wireless power transfer (WPT) are jointly optimized to minimize the whole energy consumption. To solve the formulated non-convex problem with multiple constraints and attain locally optimal solution, an iterative algorithm is proposed. Simulations show that our proposed algorithm is superior to other benchmark algorithms. (C) 2020 The Authors. Published by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Energy harvest (EH) Wireless powered communi-cation network (WPCN) Unmanned aerial vehicle (UAV) UAV trajectory Non-convex problem iterative algorithm

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On the reconstruction of material properties of a radially inhomogeneous cylindrical waveguide

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MATHEMATICAL METHODS IN THE APPLIED SCIENCES 2021年第6期44卷 4756-4769页

作者： Vatulyan, Alexandr Ovanesovich Yurov, Victor Olegovich Southern Fed Univ II Vorovich Inst Math Mech & Comp Sci Rostov Na Donu Russia

The scheme of solving the inverse problem (IP) for reconstructing three functions characterizing the radial change in the Lame parameters and in the density in a cylindrical waveguide is presented. The displacement fields corresponding to three types of loading are used as an additional information for solving the IP. An iterative process is constructed, at each step of which a direct problem is solved for the radially inhomogeneous waveguide, and the corrections to the restored functions are determined. The corrections are identified by solving the system of three Fredholm integral equations of the first kind with smooth kernels. The solution is constructed by the A. N. Tikhonov regularization method. A series of computational experiments was carried out. The role of the initial approximation and the frequency range is discussed.

关键词： cylindrical waveguide inhomogeneous properties integral Fourier transform inverse problem iterative algorithm regularization

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A constrained optimization method for blocking artifact compensation in JPEG infrared image

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SIGNAL IMAGE AND VIDEO PROCESSING 2021年第7期15卷 1361-1368页

作者： Pei, Jihong Mo, Wenying Shao, Xuhui Wang, Lixia Shenzhen Univ Sch Elect & Informat Engn Shenzhen 518060 Peoples R China

Aiming to improve the quality of JPEG decompressed infrared images, this paper presents a constrained optimization method for blocking artifact compensation. First, we define the drop value between image blocks and measure the DC component loss by the drop value. Second, a constrained optimization object function is constructed based on the DC component compensation model. Both global and local constraints are used to avoid overcompensation. Finally, the optimal compensation value is obtained using iterative processing. Experimental results show that the proposed algorithm can remove the blocking artifact in JPEG infrared image effectively and outperform the existing methods.

关键词： Blocking artifact removal DC component compensation Constrained optimization objective function iterative algorithm

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Sliding Mode Output Feedback Controller Design of Discrete-Time Markov Jump System Based on Hidden Markov Model Approach

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IEEE ACCESS 2021年 9卷 101089-101096页

作者： Xu, Ming Ma, Longhua Ma, Hongyu Xu, Zhaowen NingboTech Univ Inst Automat & Elect Engn Ningbo 315100 Peoples R China Zhejiang Cybstar Sci & Technol Co Ltd Hangzhou 311121 Peoples R China Shenzhen Polytech Inst Intelligence Sci & Engn Shenzhen 518055 Peoples R China

This paper investigates the problem of sliding mode controller design based on output feedback for discrete-time Markov jump systems. Considering the typical asynchronous phenomenon for jump systems, here we adopt the Hidden Markov Model (HMM) to quantify the asynchronous degree. Based on this, a static output feedback sliding surface is constructed. Sufficient conditions in terms of bilinear matrix inequalities are proposed ensuring the sliding motion dynamic to be stochastically stable and its H-infinity performance for the considered discrete time Markov jump systems. Moreover, the reachability of the sliding mode surface is ensured by a predesigned control law. The whole design scheme is presented by using an iterative algorithm. Finally, simulation results are presented to illustrate the effectiveness of the design methodology.

关键词： Markov processes Hidden Markov models Symmetric matrices Sliding mode control Output feedback Dynamics Licenses Sliding mode control HMM output feedback iterative algorithm

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A comparison of proton stopping power measured with proton CT and x-ray CT in fresh postmortem porcine structures

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MEDICAL PHYSICS 2021年第12期48卷 7998-8009页

作者： DeJongh, Don F. DeJongh, Ethan A. Rykalin, Victor DeFillippo, Greg Pankuch, Mark Best, Andrew W. Coutrakon, George Duffin, Kirk L. Karonis, Nicholas T. Ordonez, Caesar E. Sarosiek, Christina Schulte, Reinhard W. Winans, John R. Block, Alec M. Hentz, Courtney L. Welsh, James S. ProtonVDA LLC Naperville IL 60563 USA Northwestern Med Chicago Proton Ctr Warrenville IL USA Northern Illinois Univ Dept Phys De Kalb IL 60115 USA Northern Illinois Univ Dept Comp Sci De Kalb IL 60115 USA Argonne Natl Lab Data Sci & Learning Div 9700 S Cass Ave Argonne IL 60439 USA Loma Linda Univ Loma Linda CA 92350 USA Edward Hines Jr VA Med Ctr Radiat Oncol Serv Hines IL USA Loyola Univ Stritch Sch Med Dept Radiat Oncol 2160 S 1st Ave Maywood IL 60153 USA

Purpose: Currently, calculations of proton range in proton therapy patients are based on a conversion of CT Hounsfield units of patient tissues into proton relative stopping power. Uncertainties in this conversion necessitate larger proximal and distal planned target volume margins. Proton CT can potentially reduce these uncertainties by directly measuring proton stopping power. We aim to demonstrate proton CT imaging with complex porcine samples, to analyze in detail three-dimensional regions of interest, and to compare proton stopping powers directly measured by proton CT to those determined from x-ray CT scans. Methods: We have used a prototype proton imaging system with single proton tracking to acquire proton radiography and proton CT images of a sample of porcine pectoral girdle and ribs, and a pig's head. We also acquired close in time x-ray CT scans of the same samples and compared proton stopping power measurements from the two modalities. In the case of the pig's head, we obtained x-ray CT scans from two different scanners and compared results from high-dose and low-dose settings. Results: Comparing our reconstructed proton CT images with images derived from x-ray CT scans, we find agreement within 1% to 2% for soft tissues and discrepancies of up to 6% for compact bone. We also observed large discrepancies, up to 40%, for cavitated regions with mixed content of air, soft tissue, and bone, such as sinus cavities or tympanic bullae. Conclusions: Our images and findings from a clinically realistic proton CT scanner demonstrate the potential for proton CT to be used for low-dose treatment planning with reduced margins.

关键词： digitally reconstructed radiograph iterative algorithm proton computed tomography proton imaging proton radiography relative stopping power

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Improved modeling of leaf stomatal conductance by incorporating its highly dynamic responses to varying light conditions in Mango species (Mangifera indica L.)

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SCIENTIA HORTICULTURAE 2024年 328卷

作者： Zhuang, Jie Wang, Quan Jin, Jia Shizuoka Univ Grad Sch Sci & Technol Shizuoka 4228529 Japan Shizuoka Univ Fac Agr Shizuoka 4228529 Japan Nanning Normal Univ Inst Geog & Oceanog Nanning Peoples R China

Dramatic variations in natural light conditions can cause complex stomatal conductance responses in plant leaves but are often overlooked in current models of stomatal conductance, impeding our understanding of the internal mechanisms governing stomatal conductance (gsw) in plant leaves. Experimentally determined dynamic response patterns of gsw to various light conditions in Mangifera indica L. (Mango). The results also indicated that photosynthetic photon flux density (PPFD), the proportion of blue light (PB), vapor pressure deficit (VPD), and leaf type (Ltype) had significant effects on gsw, resulting in the popular stomatal conductance models (Jarvis, BallWoodrow-Berry (BWB), Ball-Berry-Leuning (BBL), and Unified Stomatal Optimization (USO)) having different degrees of overestimation or underestimation under varying light conditions. We have further integrated the influence of potential variables into the Jarvis, BWB, BBL, and USO models and analyzed their impact on gsw, resulting in an increase of 0.08-0.36 in R2 and 0.032-1.08 in RPD. Among the models, the improved USO model incorporating the constraints from PPFD and Ltype, exhibited the highest performance (R2 = 0.85, RPD = 2.55). Therefore, for accurate estimation of gsw, the model should take into account the light conditions and the difference between sunlit and shaded areas, especially in natural environments where light conditions change frequently.

关键词： Coupled model iterative algorithm Light quality Photosynthesis Stomatal conductance Varying light conditions

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Research on Dynamics Modeling and Simulation of Constrained Metamorphic Mechanisms

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IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY-TRANSACTIONS OF MECHANICAL ENGINEERING 2021年第2期45卷 321-336页

作者： Song, Yanyan Chang, Boyan Jin, Guoguang Wei, Zhan Li, Bo Zhu, Yongjie Tiangong Univ Sch Mech Engn Tianjin 300387 Peoples R China Tianjin Key Lab Modern Electromech Equipment Tech Tianjin 300387 Peoples R China

This paper presents a method for establishing a unified dynamics model of constrained metamorphic mechanisms. Based on the equivalent resistance, the influences of geometric constraints and/or force constraints on metamorphism are discussed, and the kinematic characteristics of metamorphic joints are described and analyzed in detail. On this basis, the metamorphic configurations of augmented Assur groups can be classified into three types, including non-collision, internal collision and external collision configurations, and the configuration complete dynamics models of augmented Assur groups are established. Then, the dynamics models of active parts, Assur groups and augmented Assur groups are summarized into a unified mathematical framework, and the unified dynamics model of constrained metamorphic mechanisms can be obtained. Based on the research mentioned above, the initial conditions of all components and the motion law of the active parts are given. The motion laws of all components, the driving force/torque of the active parts and the constraint force/torque of the metamorphic joints can be obtained by iteration and solution based on the theory that velocity and acceleration are same in an extremely brief period. Taking the planar double-folded metamorphic mechanism and the metamorphic nipper swing mechanism as examples, the computer numerical analysis and dynamic simulation are carried out to verify the correctness and effectiveness of the proposed theory and method.

关键词： Constrained metamorphic mechanisms Augmented Assur groups Dynamics iterative algorithm

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Parameterizing the Curvilinear Roofs of Traditional Chinese Architecture

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NEXUS NETWORK JOURNAL 2021年第2期23卷 475-492页

作者： Shen, Yuan Zhang, Enhe Feng, Yanxiao Liu, Siyuan Wang, Julian Qingdao Univ Technol Coll Architecture & Urban Planning Qingdao 266033 Peoples R China Penn State Univ Dept Architectural Engn University Pk PA 16802 USA Univ Cincinnati Sch Architecture & Interior Design Cincinnati OH 45221 USA

The curvilinear roofs of ancient Chinese wooden architecture feature unique functional, hierarchical, and aesthetic elements. However, the digitalization of these roofs has yet to be explored because of the lack of accurate mathematical models for these roof geometries. This research aims to parameterize the design and construction rules for these roofs as stipulated in theYingzao fashi. We first illustrate the major features of curvilinear roofs, followed by a comprehensive investigation on the raising and bending rules via the original texts and drawing samples provided in theYingzao fashiand theAnnotated yingzao fashiby Sicheng Liang. Then, the mathematical models are developed. The main contribution of this research is the transformation of the design and building rules for complex curvilinear roofs into mathematical models, enabling designers to generate such roof architecture and adding new insights to existing mathematical methods in studying ancient architecture.

关键词： Parametric design iterative algorithm Traditional architecture Logic of design Roof architecture Chinese architecture

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Robust estimation method for panel interval-valued data model with fixed effects

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JOURNAL OF STATISTICAL COMPUTATION AND SIMULATION 2024年第14期94卷 3230-3251页

作者： Zhang, Jinjin Li, Qingqing Wei, Bowen Ji, Aibing Hebei Univ Coll Math & Informat Sci Baoding 071002 Peoples R China

Panel data model with fixed effects is widely used in economic and administrative applications. However, the presence of factors: measurement errors, data variability and outliers may potentially decrease the accuracy of the model prediction. In this paper, we use panel interval-valued data to represent measurement errors and data volatility of observations. Further, we propose a corresponding panel interval-valued data model with fixed effects, in which both the response and explanatory variables are interval-valued data. To reduce the impact of outliers on our model, we propose a robust estimation method based on the iterative weighted least squares technique. Later, Monte Carlo simulation and empirical application demonstrate that our model is a suitable tool for analyzing the behaviour of panel interval-valued data.

关键词： Panel interval-valued data robust estimation iterative algorithm panel interval Box-Cox transformation

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