We introduce, for the first time in wireless communication networks, a quantum gradient descent (QGD) algorithm to maximize sum data rates in non-orthogonal multiple access (NOMA)-based simultaneously transmitting and...
详细信息
We introduce, for the first time in wireless communication networks, a quantum gradient descent (QGD) algorithm to maximize sum data rates in non-orthogonal multiple access (NOMA)-based simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-assisted multiple-input and multiple-output systems. The QGD algorithm utilizes the principles of quantum parallelism and superposition to efficiently solve the high-dimensional optimization challenges inherent in configuring transmit and receive beamformers and STAR-RIS elements. Extensive simulations demonstrate that the QGD algorithm significantly outperforms classical optimization methods, achieving up to 49.50% and 44.88% higher data rates compared to classical gradient descent algorithms for configurations with 256 STAR-RIS elements. Furthermore, the NOMA model shows substantial improvements in sum data rate performance, with gains of 179.65% and 145.61% over space division multiple access schemes under similar frameworks.
In reversible data hiding (RDH) community, researchers often train the CNN-based predictors with the Mean Square Error (MSE) loss function to evaluate the differences between original and predicted images. This will m...
详细信息
In reversible data hiding (RDH) community, researchers often train the CNN-based predictors with the Mean Square Error (MSE) loss function to evaluate the differences between original and predicted images. This will make the prediction network parameters optimized for all pixels without difference. Considering that the prediction errors in smooth areas are prioritized from the prediction error set for reversible data hiding, in this letter we propose to apply a smoothness factor into the MSE loss function. The smoothness factor used to evaluate the pixel smoothness of an image in steganography is adopted as the loss weight in the new loss function, corresponding to large values in the smooth areas and small values in the texture areas. Experimental results have shown that the CNN-based predictors trained with the proposed loss function can predict pixels more accurately in the smooth areas than using the original loss function. As a bonus, better embedding performance can be achieved by comparing with recent typical CNN-based RDH methods.
A simulation-driven surrogate parallel improved adaptive genetic algorithm (SDS-IAGA) method is proposed. This method aims to improve the efficiency of topology optimization for the automated design of antenna. The op...
详细信息
A simulation-driven surrogate parallel improved adaptive genetic algorithm (SDS-IAGA) method is proposed. This method aims to improve the efficiency of topology optimization for the automated design of antenna. The optimization process involves two stages: initialization, population screening and algorithm application. In the first stage, a coarse-mesh electromagnetic (EM) simulation model combined with a current-driven search is utilized to provide a high-quality initial population. In the second stage, variable-fidelity surrogate and correction technology assist the IAGA in optimizing the antenna topology. During this stage, the IAGA uses new adaptive crossover and mutation operators based on nonlinear improvement to enhance the efficiency in reaching the target solution. To verify the efficacy of the proposed SDS-IAGA, the design task of a planar tri-band antenna with center frequencies at 2.45 GHz/3.5 GHz/5.8 GHz is completed. The experimental results demonstrate that, compared to AGA and IAGA, the SDS-IAGA enhances the optimization efficiency of antenna topology by 62.97% and 54.22%, respectively. Furthermore, compared to existing optimization methods, SDS-IAGA can complete the target design task with fewer full-wave EM simulations.
This letter investigates reconfigurable intelligent surface (RIS)-assisted autonomous aerial vehicle (AAV) downlink networks with fluid antennas (FA), where RIS enables non-line-of-sight (NLoS) transmissions. Moreover...
详细信息
This letter investigates reconfigurable intelligent surface (RIS)-assisted autonomous aerial vehicle (AAV) downlink networks with fluid antennas (FA), where RIS enables non-line-of-sight (NLoS) transmissions. Moreover, the FA is equipped on the AAV offering dynamic antenna position adjustment, enhancing spatial diversity besides AAV deployment. We aim at total downlink rate maximization while ensuring minimum user rate requirement. We consider joint optimization of active AAV beamforming, passive RIS beamforming, AAV deployment and FA position adjustment. To address the complex problem, we propose beamfomring for RIS/AAV and FA-AAV deployment (BRAUD) scheme by employing alternative optimization, successive convex approximation (SCA) and sequential rank-one constraint relaxation (SROCR) method for the decomposed subproblems. Simulation results demonstrate the effectiveness of RIS-FA-AAV, achieving the highest rate among existing architectures without FA/AAV/RIS deployment and without proper beamforming.
In this article, we introduce a convex combination-based distributed momentum method (CDM) for solving distributed optimization to minimize a sum of smooth and strongly convex local objective functions over directed g...
详细信息
In this article, we introduce a convex combination-based distributed momentum method (CDM) for solving distributed optimization to minimize a sum of smooth and strongly convex local objective functions over directed graphs. The proposed method integrates the convex combination, row- and column-stochastic weights, and the adapt-then-combination rule. By selecting different parameters, it can be reduced to other distributed momentum methods, such as the parametric distributed momentum. CDM converges to the optimal solution at a global R-linear rate for any smooth and strongly convex function when the step-size and momentum coefficient satisfy some bounded conditions. Numerical results for some distributed optimization problems demonstrate that CDM yields a performance that is superior to that of the state-of-the-art methods.
Multivariate time series (MTS) clustering has become a critical research area. Current methods typically rely on space projection or representation learning for clustering but tend to overlook the significance and con...
详细信息
Multivariate time series (MTS) clustering has become a critical research area. Current methods typically rely on space projection or representation learning for clustering but tend to overlook the significance and contribution of MTS dimensions, leading to a failure in accurately modeling the intricate correlations and dependencies among dimensions. Meanwhile, the lack of adaptive regulation for MTS dimensions in distance measures significantly impacts clustering accuracy. In view of these issues, we propose a data-adaptive dynamic time warping (DTW) based fuzzy clustering method for MTS. This method utilizes locally weighted DTW as the kernel distance measure, enabling the adaptive regulation of MTS dimensions. To address the non-convex optimization problem associated with DTW-based clustering, we formulate a comprehensive objective function and present an efficient optimization method based on closed-form solutions. This unsupervised learning method significantly improves the precision of DTW, leading to more accurate and interpretable clustering outcomes. Extensive experiments conducted on eight public datasets, along with comparisons to 10 benchmark methods, demonstrate the competitive performance of our method in terms of both accuracy and efficiency.
When railway line sections are partially disrupted due to damage from large-scale natural disasters, it is necessary to prepare crew schedule plans for temporary timetables. In such a case, a crew schedule plan ensure...
详细信息
This article aims to establish the fundamental notions on which stability analysis in optimization is based. It is a topic of singular importance in the analysis of any optimization problem, since the lack of stabilit...
详细信息
This article aims to establish the fundamental notions on which stability analysis in optimization is based. It is a topic of singular importance in the analysis of any optimization problem, since the lack of stability can lead to serious problems in the application of the results. Our work here is of didactic nature and, consequently, it is limited to studying the basic criteria of qualitative and quantitative stability in linear programming. Formulas are provided that allow us to measure the level of each stability property by means of the so-called modulus. An important feature of our approach is that such moduli rely exclusively on the data of the nominal problem. The mathematical tools used in the paper are simple, consisting mainly in the analysis of lower/upper semicontinuity of set-valued mappings and, also, of their Lipschitz-type properties. Measuring the distance to ill-posed problems is another goal of this basic paper and some formulas to this purpose are shown. Most definitions are given for set-valued mappings between metric spaces, although the paper confines to Euclidean ones. The contents of the article could be incorporated into any introductory optimization course.
This article is devoted to the study of discrete potentials on the sphere in Rn for sharp codes. We show that the potentials of most of the known sharp codes attain the universal lower bounds for polarization for sphe...
详细信息
This article is devoted to the study of discrete potentials on the sphere in Rn for sharp codes. We show that the potentials of most of the known sharp codes attain the universal lower bounds for polarization for spherical tau-designs previously derived by the authors, where ``universal'' is meant in the sense of applying to a large class of potentials that includes absolutely monotone functions of inner products. We also extend our universal bounds to T-designs and the associated polynomial subspaces determined by the vanishing moments of spherical configurations and thus obtain the minima for the icosahedron, dodecahedron, and sharp codes coming from E8 and the Leech lattice. For this purpose, we investigate quadrature formulas for certain subspaces of Gegenbauer polynomials P-j((n)) which we call PULB subspaces, particularly those having basis {P-j((n))}(j=0)(2k+2)\{P-2k((n))}. Furthermore, for potentials with h((tau+1))<0 we prove that the strong sharp codes and the antipodal sharp codes attain the universal bounds and their minima occur at points of the codes. The same phenomenon is established for the 600-cell when the potential h satisfies h((i) )>= 0, i=1,& mldr;,15, and h((16))<= 0.
Background The French West Indies are facing increasing rates of obesity and diet-related chronic diseases. Food prices are more than 30% higher compared with mainland France, while a large part of the population is s...
详细信息
Background The French West Indies are facing increasing rates of obesity and diet-related chronic diseases. Food prices are more than 30% higher compared with mainland France, while a large part of the population is socioeconomically disadvantaged. The affordability of a healthy diet is a key issue. Objective To identify dietary shifts allowing to achieve nutritional adequacy while reducing the cost of Guadeloupean and Martinican adult diets. Methods Dietary intakes of 1112 adults (>= 16y) were obtained from a cross-sectional survey conducted on a representative sample of the Guadeloupean and Martinican populations. Diet cost was based on mean prices of 1357 foods compiled from a Martinican supermarket website. Individual optimized diets respecting all nutritional recommendations with minimized departure from the initial diet were designed under different scenarios of cost constraint: none, not exceeding the initial diet cost (COSTinit), and 10%-step reductions (COST-X%);the initial diet cost referring to the cost of the diet based on initial dietary intakes and mean food prices. Results Without cost constraint, achieving nutritional adequacy while departing the least from initial diet increased diet cost on average (+ 20%) and for 74% of adults. In COSTinit, achieving nutritional adequacy was possible for 98% of adults and induced an increase in the amount of fruit & vegetables, unrefined starches, dairy products (especially milk), eggs and vegetable fats, and a decrease in sweetened beverages (especially among < 30y), refined cereals, sweetened products, meat and *** COST-30% scenario, achieving nutritional adequacy was possible for 93% of adults and induced the same dietary shifts as in COSTinit, but modified their magnitude, notably a smaller increase of vegetables (increase of + 7 g/d in the COST-30% scenario and + 86 g/d in the COSTinit scenario, both relative to initial diet), a larger increase of dairy (+ 90 g/d and + 72 g/d, respectively) and starchy fo
暂无评论