Mitigation of inter-cell interference in visible light communication

This paper proposes the orthogonal and nonorthogonal schemes in the interference environments for visible light communication（ VLC） systems. The proposed schemes pay attention to the case when different bit streams from multiple cells are simultaneously transmitted, which consequently causes inter-cell interference（ ICI） and greatly deteriorates the bit error rate（ BER） and channel capacity performance of the system. The performance of the newdeveloped multi-cell system in indoor VLC systems is evaluated. The bipolar phase shift keying（ BPSK） modulation scheme with orthogonal pulses（ OPs） for multiple cells environments is employed to mitigate the ICI problem and improve the BER and channel capacity performances. Since the use of different OPs in each cell requires more number of OPs, which requires high bandwidth, OPs are reused at certain distances. Three different schemes, which are OPs,orthogonal and non-orthogonal pulses（ NOP） reuse, are compared. This paper investigates the impact of using these schemes and compared their performances in the ICI environments. The BER and channel capacity using the proposed schemes are comprehensively examined. Simulation and theoretical results showthat the OPs schemes are more effective in the interference areas of the room and significantly outperform NOP.

Pricing Based Power Control for Inter-Cell UAV-Assisted Vehicle-to-Vehicle Underlay Communication

The high-capacity vehicle-to-vehicle(V2 V) communication provides a promising solution to support ubiquitous media streaming and content sharing among vehicles.To extend the V2 V links to multiple cells and manage the inter-cell interference,we proposed an UAV-assisted inter-cell V2 V communication model,in which a shared UAV node is placed in the center of V2 V users.By charging the V2 V users underlay spectrum access fee,the cellular network earn profit at the cost of encountering co-channel interference from V2 V links.A Stackelberg game is formulated to model the interactions between the V2 V links and the cellular links,which are the game follower and the leader respectively.Their utility functions are maximized in terms of accessing price as well as transmit power of V2 V users and UAV relays.Simulation evaluations verify that the power-price tradeoff between V2 V network and cellular network has significant potentials to enhance their utility.

COOPERATIVE DIRECTIONAL INTER-CELL HANDOVER SCHEME IN HIGH ALTITUDE PLATFORM COMMUNICATIONS SYSTEMS

A novel Cooperative Directional inter-cell Handover Scheme(CDHS) for High Altitude Platform(HAP) communications systems is proposed,in which the handover target cell and the two cells adjacent to this handover target cell work cooperatively to exploit the traffic fluctuation to improve handover performance.Users in the overlap area of the overloaded handover target cell will be forced to handover directionally before their optimal handover boundary in order to free up resources for the handover calls which would otherwise be dropped due to the shortage of resources and queue time out.Simulation results show that the handover call dropping probability is greatly reduced(at least 60%) compared with the general queue handover scheme,with little performance reduction to the call blocking probability,and the Not in the Best Cell(NBC) average time is only increased moderately.Moreover,an optimal cell radius can be achieved for a specific platform speed by minimizing the unified system performance,which is the linear combination of the handover call dropping probability and the NBC average time.

Optimization Design of the Multi-Layer Cross-Sectional Layout of An Umbilical Based on the GA-GLM

Marine umbilical is one of the key equipment for subsea oil and gas exploitation,which is usually integrated by a great number of different functional components with multi-layers.The layout of these components directly affects manufacturing,operation and storage performances of the umbilical.For the multi-layer cross-sectional layout design of the umbilical,a quantifiable multi-objective optimization model is established according to the operation and storage requirements.Considering the manufacturing factors,the multi-layering strategy based on contact point identification is introduced for a great number of functional components.Then,the GA-GLM global optimization algorithm is proposed combining the genetic algorithm and the generalized multiplier method,and the selection operator of the genetic algorithm is improved based on the steepest descent method.Genetic algorithm is used to find the optimal solution in the global space,which can converge from any initial layout to the feasible layout solution.The feasible layout solution is taken as the initial value of the generalized multiplier method for fast and accurate solution.Finally,taking umbilicals with a great number of components as examples,the results show that the cross-sectional performance of the umbilical obtained by optimization algorithm is better and the solution efficiency is higher.Meanwhile,the multi-layering strategy is effective and feasible.The design method proposed in this paper can quickly obtain the optimal multi-layer cross-sectional layout,which replaces the manual design,and provides useful reference and guidance for the umbilical industry.

Congestion Relief in Downlink OFDMA Cellular System Using Inter-Cell Relay

This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighboring cells. It is shown that when using inter-cell relay, the number of calls in the congestion cell can be significantly increased. The congestion cell is divided into two parts. One is called non-relay area(NRA), in which a call directly communicates with the base station(BS) of a congested cell. The other is called relay area(RA), in which a call communicates with the BS of a neighboring cell through a relay station(RS). The two parts have different user-call densities. By adjusting the densities of two parts, we will maximize the number of supported calls inside a congested cell. The results show the benefits gained from inter-cell relay in congestion relief, which can reduce cell congestion by fully utilizing the available resources in the neighboring cells.

Web Layout Design of Large Cavity Structures Based on Topology Optimization

Large cavity structures are widely employed in aerospace engineering, such as thin-walled cylinders, blades andwings. Enhancing performance of aerial vehicles while reducing manufacturing costs and fuel consumptionhas become a focal point for contemporary researchers. Therefore, this paper aims to investigate the topologyoptimization of large cavity structures as a means to enhance their performance, safety, and efficiency. By usingthe variable density method, lightweight design is achieved without compromising structural strength. Theoptimization model considers both concentrated and distributed loads, and utilizes techniques like sensitivityfiltering and projection to obtain a robust optimized configuration. The mechanical properties are checked bycomparing the stress distribution and displacement of the unoptimized and optimized structures under the sameload. The results confirm that the optimized structures exhibit improved mechanical properties, thus offering keyinsights for engineering lightweight, high-strength large cavity structures.

Optimizing trade-offs between light transmittance and intraspecific competition under varying crop layouts in a maize-soybean strip relay cropping system

Light is one of the most important environmental factors for plant growth and development.In relay cropping systems,crop layouts influence light distribution,affecting light use efficiency(LUE).However,the response of light interception,light conversion,and LUE for relay maize and relay soybean to different crop layouts remains unclear.We aimed to quantify the effect of crop layout on intraspecific and interspecific competition,light interception,light conversion,LUE,and land productivity between relay maize and relay soybean.We conducted a field experiment for four consecutive years from 2017 to 2020 in Sichuan province,China,comparing different crop layouts(bandwidth 2.0 m,row ratio 2:2;bandwidth 2.4 m,row ratio 2:3;bandwidth 2.8 m,row ratio 2:4),with sole maize and sole soybean as controls.The results showed that relay maize in the 2.0 m bandwidth layout had the largest leaf area index and plant biomass,the lowest intraspecific competitive intensity and the highest aggressiveness.Compared to a bandwidth of 2.0 m,a bandwidth of 2.8 m significantly decreased relay maize leaf area index by 11%and plant biomass by 24%,while a 2.4 m bandwidth caused roughly half these reductions.The 2.0 m bandwidth layout also significantly improved crop light interception and LUE compared to sole maize.The light interception,light interception rate,light conversion rate and LUE in relay maize all decreased significantly with increasing bandwidth,but they increased in relay soybean.The increased light transmittance to the lower and middle canopy with increasing bandwidth did not compensate for the loss of relay maize yield caused by increased intraspecific competition.However,it enhanced the yield of relay soybeans.Increasing the bandwidth by 80 cm increased the relay maize intraspecific competition by 580%,and reduced maize yield by 33%,light interception by 12%,and LUE by 18%.In contrast,the relay soybean intraspecific competition was reduced by 64%,and the soybean yield was increased by 26%,light interception by 32%and LUE by 46%.Relay cropping systems with a 2.0 m bandwidth optimize the trade-off between light transmittance and intraspecific competition of relay crops.These systems achieve the highest LUE,group yield and economic benefits,making them a recommended crop layout for the southwest regions of China.Our study offers valuable insights for developing strip relay cropping systems that maximize light utilization and contributes to the theoretical understanding of efficient sunlight use in relay cropping practices.

Development of Fixture Layout Optimization for Thin-Walled Parts:A Review

An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.

Performance-Oriented Layout Synthesis for Quantum Computing

Layout synthesis in quantum computing is crucial due to the physical constraints of quantum devices where quantum bits(qubits)can only interact effectively with their nearest neighbors.This constraint severely impacts the design and efficiency of quantum algorithms,as arranging qubits optimally can significantly reduce circuit depth and improve computational performance.To tackle the layout synthesis challenge,we propose an algorithm based on integer linear programming(ILP).ILP is well-suited for this problem as it can formulate the optimization objective of minimizing circuit depth while adhering to the nearest neighbor interaction constraint.The algorithm aims to generate layouts that maximize qubit connectivity within the given physical constraints of the quantum device.For experimental validation,we outline a clear and feasible setup using real quantum devices.This includes specifying the type and configuration of the quantum hardware used,such as the number of qubits,connectivity constraints,and any technological limitations.The proposed algorithm is implemented on these devices to demonstrate its effectiveness in producing depth-optimal quantum circuit layouts.By integrating these elements,our research aims to provide practical solutions to enhance the efficiency and scalability of quantum computing systems,paving the way for advancements in quantum algorithm design and implementation.

Optimizing wind farm layout for enhanced electricity extraction using a new hybrid PSO-ANN method

With the growing need for renewable energy,wind farms are playing an important role in generating clean power from wind resources.The best wind turbine architecture in a wind farm has a major influence on the energy extraction efficiency.This paper describes a unique strategy for optimizing wind turbine locations on a wind farm that combines the capabilities of particle swarm optimization(PSO)and artificial neural networks(ANNs).The PSO method was used to explore the solution space and develop preliminary turbine layouts,and the ANN model was used to fine-tune the placements based on the predicted energy generation.The proposed hybrid technique seeks to increase energy output while considering site-specific wind patterns and topographical limits.The efficacy and superiority of the hybrid PSO-ANN methodology are proved through comprehensive simulations and comparisons with existing approaches,giving exciting prospects for developing more efficient and sustainable wind farms.The integration of ANNs and PSO in our methodology is of paramount importance because it leverages the complementary strengths of both techniques.Furthermore,this novel methodology harnesses historical data through ANNs to identify optimal turbine positions that align with the wind speed and direction and enhance energy extraction efficiency.A notable increase in power generation is observed across various scenarios.The percentage increase in the power generation ranged from approximately 7.7%to 11.1%.Owing to its versatility and adaptability to site-specific conditions,the hybrid model offers promising prospects for advancing the field of wind farm layout optimization and contributing to a greener and more sustainable energy future.

GNN Representation Learning and Multi-Objective Variable Neighborhood Search Algorithm for Wind Farm Layout Optimization

With the increasing demand for electrical services,wind farm layout optimization has been one of the biggest challenges that we have to deal with.Despite the promising performance of the heuristic algorithm on the route network design problem,the expressive capability and search performance of the algorithm on multi-objective problems remain unexplored.In this paper,the wind farm layout optimization problem is defined.Then,a multi-objective algorithm based on Graph Neural Network(GNN)and Variable Neighborhood Search(VNS)algorithm is proposed.GNN provides the basis representations for the following search algorithm so that the expressiveness and search accuracy of the algorithm can be improved.The multi-objective VNS algorithm is put forward by combining it with the multi-objective optimization algorithm to solve the problem with multiple objectives.The proposed algorithm is applied to the 18-node simulation example to evaluate the feasibility and practicality of the developed optimization strategy.The experiment on the simulation example shows that the proposed algorithm yields a reduction of 6.1% in Point of Common Coupling(PCC)over the current state-of-the-art algorithm,which means that the proposed algorithm designs a layout that improves the quality of the power supply by 6.1%at the same cost.The ablation experiments show that the proposed algorithm improves the power quality by more than 8.6% and 7.8% compared to both the original VNS algorithm and the multi-objective VNS algorithm.

Optimizing Memory Access Efficiency in CUDA Kernel via Data Layout Technique

Over the past decade, Graphics Processing Units (GPUs) have revolutionized high-performance computing, playing pivotal roles in advancing fields like IoT, autonomous vehicles, and exascale computing. Despite these advancements, efficiently programming GPUs remains a daunting challenge, often relying on trial-and-error optimization methods. This paper introduces an optimization technique for CUDA programs through a novel Data Layout strategy, aimed at restructuring memory data arrangement to significantly enhance data access locality. Focusing on the dynamic programming algorithm for chained matrix multiplication—a critical operation across various domains including artificial intelligence (AI), high-performance computing (HPC), and the Internet of Things (IoT)—this technique facilitates more localized access. We specifically illustrate the importance of efficient matrix multiplication in these areas, underscoring the technique’s broader applicability and its potential to address some of the most pressing computational challenges in GPU-accelerated applications. Our findings reveal a remarkable reduction in memory consumption and a substantial 50% decrease in execution time for CUDA programs utilizing this technique, thereby setting a new benchmark for optimization in GPU computing.

基于网格归一化Astar算法的船舶管路布置

为解决船舶管路布置方法中目前存在的依靠人工经验调节算法参数,权重系数的设置量级差距较大,以及求解布置方案单一的问题,提出一种网格归一化Astar (GNAstar)的布置方法.首先,采用包围盒和网格法建立数学模型.其次,通过分支管路拆分、网格标记值和父子网格搜索策略,使每一路径节点由不同目标的归一化权重值来共同决定,将传统Astar算法仅考虑长度的目标扩展成包括长度、弯头消耗和安装适用性的管路综合布置目标.最后,通过仿真案例将GNAstar算法与传统Astar算法进行对比分析,并以船舶机舱内不同管路系统为例,与文献中的蚁群算法和粒子群-Astar算法开展进一步比较.结果表明,GNAstar算法可获得有效的工程解,设计人员可通过设置不同目标的归一化权重系数来获得相应的布置方案.

明代勺园水系空间格局及其景观意象营造研究

米万钟在北京修建的勺园是晚明时期私家园林的传世经典之作。借助明代勺园的历史图像及文献中形象与意象的描述,探讨水系景观在晚明时期园林中的积极作用;从空间营造视角出发,深度剖析园林水系景观的营造内核;将研究视点从平面图像转移到园林空间体系,明晰勺园水系景观一河两岸的空间格局,并梳理勺园水系景观意象与营造思想;最终通过分析明代水系景观空间格局的转变,探究晚明时期政治背景、文化内涵及时代风格等对园林水景空间的影响,探寻明代北方园林水系景观形成的历史契机与意义。旨在丰富现有传统园林水系景观营造理论,将水系景观空间作为继承园林文化传统的重要支撑,为当代园林水系景观营造及研究提供理论依据。

考虑人员特性和场景布局的西藏高原人群疏散仿真研究

为提高突发事件下西藏高原人流聚集场所人员应急疏散能力,基于模糊规则的社会力模型,结合AnyLogic对高原人群疏散行为特性进行研究。首先研究影响西藏高原人员应急疏散的因素,根据模糊规则确定因素对人员疏散速度的影响;以八廓步行街为例建立突发事件下西藏高原人员疏散仿真模型,探究人员性别、年龄、环境熟悉程度、高原适应能力、出口宽度和出口布局6因素对疏散过程的影响;采用正交实验设计分析6因素综合作用对西藏高原人员应急疏散过程产生的影响,并提出最优组合方案。研究结果表明:6因素对西藏高原人群应急疏散过程均有不同程度影响,其中疏散人员的年龄影响最大,性别影响最小,并结合仿真分析提出相应引导策略。研究结果可为西藏高原地区居民在紧急疏散情况下的行动提供科学指导和决策支持。

教育、科技、人才一体化布局下高校有组织科研的治理创新

高校是构建教育、科技、人才一体化布局的关键一环。通过对一体化布局的体系构成、结构逻辑与网络特征进行考察和分析,指出高校科技创新是推进教育、科技、人才一体化建设的重要结合点。回顾和总结党的十八大以来党领导高校科技创新取得的历史性进展与宝贵经验,指出有组织科研将引发高校科技创新的深刻变革。作为大学治理的重要组成部分,加快高校科技创新治理结构的网络化育成,是推动和实现高校有组织科研治理创新的前提和基础。在新时代新征程上,应从充分发挥新型举国体制优势、全面提升高校科技创新体系整体效能、构建以“人”为中心的科技创新治理体系等方面着手,探索以治理创新推进高校有组织科研的实践进路。

基于建筑高度与布局形式的街区夏季风、热环境模拟与优化

为了分析建筑高度与布局形式对城市风、热环境的影响,从而通过优化街区建筑格局改善城市风、热环境质量,构建3种建筑高度、4种布局形式下街区的建筑三维模型,采用Fluent软件模拟12种建筑格局条件下街区夏季的风、热环境,选用风速、温度、舒适指数等分析街区高度为1.5 m处的风、热环境特征;以山东省青岛市某街区为例,模拟并优化街区夏季高度为1.5 m处的风、热环境。结果表明:行列式布局街区的风场、温度场与舒适指数分布均匀,舒适区面积比最大,平均温度、高温区面积比和舒适指数较小,风、热环境质量最佳;围合式布局街区的静风区面积比、温度与舒适指数高值区面积较大,风、热环境质量最差;建筑高度与布局形式对街区风、热环境影响显著;随着街区建筑高度的增大,风、热环境质量劣化;多层建筑街区风场、温度与舒适指数分布均匀,通风效率较高,热量容易扩散,风、热环境质量最佳;高层建筑街区风速与风影区面积较大,热量扩散困难,风、热环境质量较差;通过调整建筑布局形式、体型、拆除部分建筑等优化措施能有效改善街区的风、热环境质量。

国外科研机构行业与区域布局经验借鉴及启示

选取欧美及亚太地区4个典型国家的国家实验室、高等院校科研中心及企业研发中心等科研机构作为研究对象,通过对其行业分布与区域布局进行深入分析,总结其成功经验和创新模式。研究发现,国外科研机构的成功在很大程度上得益于明确的国家战略导向、产学研紧密结合的生态系统、灵活高效的资源配置机制,以及对创新区域的精心规划与政策扶持,同时国外科研机构普遍重视跨行业合作,形成产业链协同效应,并依托区域特色资源,打造具有全球竞争力的产业集群。基于上述分析,提出一系列对中国科研机构行业布局与区域发展战略的启示与建议,强调应加强顶层设计,均衡科研机构地区布局,开展适应区域创新发展的技术研发,并充分保障科研机构的自主权,支撑和引领中国的科技创新和经济社会高质量发展。

国家考古遗址公园布局现状与发展策略研究

国家考古遗址公园作为大遗址保护利用的创新举措,是对中华文明演进史进行叙事的重要形式。当前国家考古遗址公园在数量、类型和布局方面,与我国源远流长的历史和丰富的大遗址资源相比,还不足以构成完整体系来讲好中国故事。本文依托四批次国家考古遗址公园相关数据,以在时空维度上讲述“中国故事”为发展目标,利用定性与定量相结合的综合评价指标体系和Arcgis空间分析方法,较准确地反映出国家考古遗址公园空间分布特征及空间布局的合理性,进而提出针对性的体系化发展策略,以期为国家考古遗址公园实现体系化发展目标提供决策依据。

城市布局与北齐文学的差异化发展和一体化趋向

晋阳、邺都、洛阳是北齐的三个中心城市,这种多中心的城市布局给北齐文学发展带来两种趋向:一种,三地文学在风格上呈现出差异化发展情状,盛行于晋阳的霸府文学旨在服务军国大政,成长于邺都的台省文学以诗歌为主要样式,产生于洛阳的行役文学和怀古诗文以吊古兴悲为感情基调。另一种,三地文学在文体文风上相近,表现出一体化趋向。文体上,由重文轻诗转变为重视作文而又不忽视诗;诗风上,由各有旨趣转变为对情采和丽辞的普遍追求;审美上,由重实用转变为重感悟;写作手法上,由重写实转变为重抒情。差异化发展多为集体写作,一体化趋向则属个人创作,两者互为补充,共同构成北齐文学的基本面貌,并对隋唐文学发展产生不同的影响。