Communication Resource-Efficient Vehicle Platooning Control With Various Spacing Policies

Platooning represents one of the key features that connected automated vehicles may possess as it allows multiple automated vehicles to be maneuvered cooperatively with small headways on roads. However, a critical challenge in accomplishing automated vehicle platoons is to deal with the effects of intermittent and sporadic vehicle-to-vehicle data transmissions caused by limited wireless communication resources. This paper addresses the co-design problem of dynamic event-triggered communication scheduling and cooperative adaptive cruise control for a convoy of automated vehicles with diverse spacing policies. The central aim is to achieve automated vehicle platooning under various gap references with desired platoon stability and spacing performance requirements, while simultaneously improving communication efficiency. Toward this aim, a dynamic event-triggered scheduling mechanism is developed such that the intervehicle data transmissions are scheduled dynamically and efficiently over time. Then, a tractable co-design criterion on the existence of both the admissible event-driven cooperative adaptive cruise control law and the desired scheduling mechanism is derived. Finally, comparative simulation results are presented to substantiate the effectiveness and merits of the obtained results.

Distributed Multicircular Circumnavigation Control for UAVs with Desired Angular Spacing

This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary target.By defining a coordinated error relative to neighboring angular spacing,under the premise that target information is perfectly accessible by all nodes,a centralized circular enclosing control strategy is derived for multiple UAVs connected by an undirected graph to allow for formation behaviors concerning the moving target.Besides,to avoid the requirement of target’s states being accessible for each UAV,fixed-time distributed observers are introduced to acquire the state estimates in a fixed-time sense,and the upper boundary of settling time can be determined offline irrespective of initial properties,greatly releasing the burdensome communication traffic.Then,with the aid of fixed-time distributed observers,a distributed circular circumnavigation controller is derived to force all UAVs to collaboratively evolve along the preset circles while keeping a desired angular spacing.It is inferred from Lyapunov stability that all errors are demonstrated to be convergent.Simulations are offered to verify the utility of proposed protocol.

Lamellar water induced quantized interlayer spacing of nanochannels walls

The nanoscale confinement is of great important for the industrial applications of molecular sieve,desalination,and also essential in bio-logical transport systems.Massive efforts have been devoted to the influence of restricted spaces on the properties of confined fluids.However,the situation of channel-wall is crucial but attracts less attention and remains unknown.To fundamentally understand the mechanism of channel-walls in nanoconfinement,we investigated the interaction between the counter-force of the liquid and interlamellar spacing of nanochannel walls by considering the effect of both spatial confinement and surface wettability.The results reveal that the nanochannel stables at only a few discrete spacing states when its confinement is within 1.4 nm.The quantized interlayer spacing is attributed to water molecules becoming laminated structures,and the stable states are corresponding to the monolayer,bilayer and trilayer water configurations,respectively.The results can potentially help to understand the characterized interlayers spacing of graphene oxide membrane in water.Our findings are hold great promise in design of ion filtration membrane and artificial water/ion channels.

Regulation effect of the grille spacing of a funnel-type grating water–sediment separation structure on the debris flow performance

The size of pores or the grille spacing of water–sediment separation structures directly affects their regulation effect on the debris flow performance.A suitable pore size or grille spacing can effectively improve the water–sediment separation ability of the structure.The new funnel-type grating water–sediment separation structure(FGWSS)combines vertical and horizontal structures and provides a satisfactory water–sediment separation effect.However,the regulation effect of the grille spacing of the structure on the debris flow performance has not been studied.The regulation effect of the structure grille spacing on the debris flow performance is studied through a flume test,and the optimal structure grille spacing is obtained.An empirical equation of the relationship between the relative grille spacing of the structure and the sediment separation rate is established.Finally,the influence of the water–sediment separation structure on the regulation effect of debris flows is examined from two aspects:external factors(properties of debris flows)and internal factors(structural factors).The experimental results show that the gradation characteristics of solid particles in debris flows constitute a key factor affecting the regulation effect of the structure on the debris flow performance.The optimum grille spacing of the FGWSS matches the particle size corresponding to the material distribution curves d85~d90 of the debris flow.The total separation rate of debris flow particles is related to the grille spacing of the structure and the content of coarse and fine particles in the debris flow.

Horizontal well spacing optimization and gas injection simulation for the ultra-low-permeability Yongjin reservoir

Optimal spacing for vertical wells can be effectively predicted with several published methods,but methods suitable for assessing the proper horizontal well spacing are rare.This work proposes a method for calculating the optimal horizontal well spacing for an ultra-low permeability reservoir e the Yongjin reservoir in the Juggar Basin,northwestern China.The result shows that a spacing of 640m is the most economical for the development of the reservoir.To better develop the reservoir,simulation approaches are used and a new model is built based on the calculated well spacing.Since the reservoir has an ultralow permeability,gas injection is regarded as the preferred enhanced oil recovery(EOR)method.Injection of different gases including carbon dioxide,methane,nitrogen and mixed gas are modelled.The results show that carbon dioxide injection is the most efficient and economical for the development of the reservoir.However,if the reservoir produces enough methane,reinjecting methane is even better than injecting carbon dioxide.

Evaluation of Well Spacing for Primary Development of Fractured Horizontal Wells in Tight Sandstone Gas Reservoirs

Methods for horizontal well spacing calculation in tight gas reservoirs are still adversely affected by the complexity of related control factors,such as strong reservoir heterogeneity and seepage mechanisms.In this study,the stress sensitivity and threshold pressure gradient of various types of reservoirs are quantitatively evaluated through reservoir seepage experiments.On the basis of these experiments,a numerical simulation model(based on the special seepage mechanism)and an inverse dynamic reserve algorithm(with different equivalent drainage areas)were developed.The well spacing ranges of Classes I,II,and III wells in the Q gas field are determined to be 802–1,000,600–662,and 285–400 m,respectively,with their average ranges as 901,631,and 342.5 m,respectively.By considering both the pairs of parallel well groups and series well groups as examples,the reliability of the calculation results is verified.It is shown that the combination of the two models can reduce errors and provide accurate results.

Effect of Variety and Plant Spacing on Growth and Yield of Groundnuts (Arachis hypogaea L.)

A field experiment was carried out to determine the effect of variety and plant spacing on yield and growth of groundnuts. The field experiment was laid in a 3 × 3 factorial experiment in a Randomized Complete Block Design (RCBD) with three (3) replications. The factor A included three (3) groundnut varieties (Nkatie Sari, Sum Nutt 22 and Yenyawoso) and Factor B was the three (3) spacing of 30 cm × 15 cm, 30 cm × 30 cm and 30 cm × 40 cm. All recommended agronomic practices were followed. Data was collected from eight (8) tagged plants. Growth data were recorded on plant height, number of branches, number of leaves, and the number of flowers while yield data were collected on the number of flowers, number of pods per plant, 100 seeds weight and the pod yield (kg/ha). The plant spacing significantly influenced (P < 0.05) the growth and yield parameters. Groundnut grown at a spacing of 30 cm × 15 cm produced the maximum plant height, whereas the maximum number of leaves, number of branches and number of flowers were produced from 30 cm × 40 cm. Yenyawoso variety with a wider plant spacing performed better vegetatively among all the varieties. The Yenyawoso variety produced the highest number of pods, 100 seeds weight and pod yield as compared to the other varieties. Also, Yenyawoso at 30 cm × 40 cm spacing and Nkatie Sari at 30 cm × 15 cm spacing produced the maximum pod yield.

Inter-Row Spacing of PV Power Plant

When designing a solar power plant, it is much more important to avoid the shadow on the PV Panels. As the shadow falls on the PV Panels;it significantly reduces the generation of required power as planned and designed. This research paper and case study will help a lot to avoid shadow, especially when selecting inter-row spacing between the strings of solar power plants.

An unequal fracturing stage spacing optimization model for hydraulic fracturing that considers cementing interface integrity

Determining reasonable fracturing stage spacing is the key to horizontal well fracturing.Different from traditional stage spacing optimization methods based on the principle of maximum stimulated reservoir volume,in this paper,by considering the integrity of the wellbore interface,a fracture propagation model was established based on displacement discontinuity method and the competition mechanism of multifracture joint expansion,leading to the proposal of an unequal stage spacing optimization model.The results show that in the first stage,the interfacial fractures spread symmetrically along the axis of the central point during that stage,while in the second and subsequent stages,the interfacial fractures of each cluster extend asymmetrically along the left and right sides.There are two kinds of interface connectivity behaviour:in one,the existing fractures first extend and connect within the stage,and in the other,the fractures first extend in the direction close to the previous stage,with the specific behaviour depending on the combined effect of stress shadow and flow competition during hydraulic fracture expansion.The stage spacing is positively correlated with the number of fractures and Young’s modulus of the cement and formation and is negatively correlated with the cluster spacing and horizontal principal stress difference.The sensitivity is the strongest when the Young’s modulus of the cement sheath is 10-20 GPa,and the sensitivity of the horizontal principal stress difference is the weakest.

Experimental Study on Interference Effect of Three Risers Arranged in Tandem with Variable Spacing Ratios

Taking the three-riser group arranged in tandem as the research subject,an experimental study was carried out on the risers arranged in tandem.The purpose is to explore the sensitivity of the dynamic response of each riser to spacing ratio and reveal the physical mechanism of riser groups under the interference effect.The spacing ratios of the adj acent risers are 4.0,5.0,6.0,and 8.0.At the spacing between the risers of 4.0D,the strong feedback effect increases the cross-flow(CF) displacement amplitude of the upstream riser.The shielding effect is the key factor affecting the interference effect on the midstream and downstream risers.At low reduced velocities,the shielding area initially appears,the displacement amplitude of the midstream and downstream risers varies greatly,the vibration of the two risers is still dominated by the first-order mode,and the transition between adjacent vibration modes is restrained.The multi-frequency superposition phenomenon is very significant at high reduced velocities.The most sensitive interference spacing under the test conditions is obtained.Due to the separation of the incoming flow and the double shielding effect of the upstream and midstream risers,the regular vortex-induced vibration in the wake area of the downstream riser is broken,and the vibration in the two directions is weakened.In general,the interference effect is more significant for the CF vibration of the three-riser groups than the in-line(IL) vibration.

Relationship between fracture spacing and bed thickness in sedimentary rocks:Approach by means of Michaelis-Menten equation

Fractures occur in nearly all rocks at the Earth’s surface and exert essential control on the mechanical strengths of rock masses and permeability.The fractures strongly impact the stability of geological or man-made structures and flow of water and hydrocarbons,CO_(2) and storing waste.For this,the dependence of opening mode fracture spacing(s)on bed thickness(t)in sedimentary basins(reservoirs)is studied in this context.This paper shows that the MichaeliseMenten equation can provide an algebraic expression for the nonlinear s-t relationship.The two parameters have clear geological meanings:a is the maximum fracture spacing which can no longer increase with increasing t,and b is the characteristic bed thickness when s=0.5a.The tensile fracture strength(C)of the brittle beds during the formation of tensile fractures can be estimated from the two parameters.For sandstones of 16 areas reported in the literature,C ranges from 2.7 MPa to 15.7 MPa with a mean value of 8 MPa,which lies reasonably within the range of tensile strengths determined experimentally.This field-based approach by means of MichaeliseMenten equation provides a new method for estimating the tensile fracture strength of rock layers under natural conditions.

Influence of Dowel Center Spacing on Chamfered-Joint Components Made byCupressus funebris Wood

The traditional tenon and mortise joint has low processing efficiency and a weak theoretical basis,making the structure easy to deform and damage,reducing the safety,and increasing waste of resources.This study aims to determine the optimum dowel center spacing parameter for chamfered-joint components and the maximum value of the strength of joints loaded into bending strength and tensile strength.In this study,an integrated opti-mization method combining the single-factor test and one-way ANOVA analysis was proposed to study the influ-ence of the dowel center spacing on the bending strength and the tensile strength of chamfered-joint components made by Cupressus funebris wood.The results revealed that the bending strength of chamfered-joint components decreases linearly with the increase of the dowel center spacing.In addition,the tensile strength of chamfered-joint components increases first and then decreases with the increase of the dowel center spacing,showing para-bola change.The relational expression between dowel center spacing,the bending strength,dowel center spacing and the tensile strength were obtained.

3D MERGE与3D SPACE STIR序列在腰椎间盘突出症检查中的应用比较

目的:对比三维多回波恢复梯度回波(3D MERGE)、三维可变反转角快速自旋回波(3D SPACE STIR)序列在腰椎间盘突出症(LDH)检查中的应用效果。方法:选择2020年1月~2022年11月收治的135例LDH患者,回顾性分析患者临床和磁共振成像(MRI)资料,所有患者均接受常规MRI扫描及3D MERGE、3D SPACE STIR序列扫描,对比3D MERGE、3D SPACE STIR序列测量神经根直径的一致性,评价两种序列的图像质量参数[信噪比(SNR)、对比噪声比(CNR)]、图像清晰度评分。结果:3D MERGE和3D SPACE STIR序列测量的L3~S1神经根直径比较差异无统计学意义(P>0.05),且两组序列测量的L3、L4、L5和S1直径均显示出较高相关性(r=0.957,0.986,0.975,0.972,P<0.05);3D MERGE序列的SNR及CNR均高于3D SPACE STIR序列,神经根显示分级、图像清晰度评分优于3D SPACE STIR序列,差异有统计学意义(P<0.05)。结论:3D MERGE、3D SPACE STIR序列在LDH神经根直径测量中具有极高一致性,3D MERGE序列较3D SPACE STIR序列能够更清晰显示神经跟的解剖形态,图像质量更好。

“能耗双控”向“碳排放双控”转变下的企业政策响应研究——以浙江省为例

具有负外部性的复杂环境政策对企业的影响和企业的应对策略之间缺乏联动性的整体研究,因此,论文提出DIIS政策文本分析法、DANP网络分析法和SPACE矩阵融合的企业环境政策响应模型(DDS),对“能耗双控”向“碳排放双控”转变形势下浙江省工业企业的政策响应开展研究和实证分析。建立“能耗双控”和“碳排放双控”政策库,通过基于DIIS理论的政策文本分析,形成政策、经济、社会、技术四个维度的18项影响因素;结合问卷调研,通过DANP法分析得到8种企业类别的环境政策影响指标权重;进而将指标与权重映射到SPACE矩阵,最终得到不同企业的应对策略选择。结果表明:(1)不同类型的企业响应程度不同,国有企业偏向于响应政策调控,民营企业偏向于对市场竞争和技术突破做出响应;(2)产业链低碳转型等社会性的因素受到所有企业的关注,而资源倾斜、低碳人才培养、核算标准制定等因素普遍被企业忽视;(3)综合考虑不同企业响应策略,建议政府部门应针对企业特点精准施策。

国内“大思政课”研究的现状、热点与展望--基于CiteSpace的核心期刊论文可视化分析

“大思政课”是近年的一个新议题。自习近平总书记作出关于“大思政课”的重要论述以来,“大思政课”建设在全国积极推进,成为新时代用党的创新理论铸魂育人的重要抓手。学界对这一领域的研究成果持续涌现。借助Cite Space文献计量软件对中国知网CNKI数据库中2021-2023年间350篇核心期刊论文的发文量、作者、机构、关键词进行可视化分析,近三年学界的研究热点聚焦“大思政课”的本体论、认识论、价值论、方法论以及一体化等方面。未来,学界还应以多学科交叉和多主体融合实现“大思政课”研究的系统化,以理论和实践结合提升“大思政课”研究的科学化,以破解技术遮蔽与AI赋能强化“大思政课”研究的数字化,以研究反哺教学,不断增强“大思政课”立德树人实效。

国家考古遗址公园研究文献可视化分析

梳理分析国家考古遗址公园研究文献是践行“保护第一、加强管理、挖掘价值、有效利用、让文物活起来”的新时代文物工作的重要思路。运用文献分析软件Cite Space对中国知网(CNKI)数据库1985—2023年国家考古遗址公园研究的477篇文献进行计量统计研究。研究发现:学者在理论拓展、政策解读、方法实践、路径探讨并辅以案例分析等方面有较丰富的研究成果,这些成果聚焦遗址保护、阐释与展示、国家公园、文旅融合等专题。但在理论和实证方面体现活化利用、社区参与、公众共享、数字化、可持续发展等方面的研究成果略显薄弱,在学科交叉、研究方法、技术手段等方面还需加强。未来需从突出国家属性、促进全民共享等视角提升理论与实践的科学研究水平,加强研究机构之间的合作交流。本研究为整体把握国家考古遗址公园的目标定位与发展态势,推动可持续发展提供建议。

用户界面评价研究现状及发展趋势

文章对用户界面评价的研究现状和内容进行梳理和分析,总结其存在的问题并对未来的研究提出展望。以WOS和CNKI数据库中用户界面评价文献为研究对象,运用CiteSpace软件进行可视化分析,从用户界面评价所采用生理感知技术和评价方法阐述界面设计评价的研究现状。归纳整理了用户界面评价的研究内容和方法技术,总结了存在的问题和挑战,梳理了发展趋势。用户界面评价研究推动界面设计效率提高,尽管当前的研究存在不足,但随新方法提出和应用,未来将突破挑战,对用户界面评价和设计起到关键作用。

可视化知识图谱分析:多维贫困测度研究回溯与前瞻

运用Cite Space文献计量分析软件,对中国知网2005年1月至2023年1月间多维贫困测度的核心期刊文献进行可视化分析.研究结果表明,多维贫困测度研究呈现出初步探索阶段弱关注、迅猛发展阶段热研究、持续升温阶段热关注的特点,多维贫困、精准扶贫、相对贫困、贫困测度是该领域的研究热点.

医院文化多院区同质化探索研究

目的通过分析医院文化多院区建设现状,探索医院文化多院区建设的影响因素,有针对性地提出多院区文化融合发展策略。方法运用Cite Space对当前多院区文化进行文献年度统计和知识图谱分析,同时以浙江省某公立口腔医院为例,对110名员工进行问卷调查,开展医院文化多院区建设影响因素分析。结果从2020年起,医院文化多院区的研究文献开始增加,2020—2022年期间,年度发文量快速增长,关键词知识图谱显示,公立医院多院区的研究方向逐渐多样化,“文化建设”突现的时间为2019—2020年,突现强度为1.47,多院区文化建设成为多院区研究的热点关键词。根据Pearson相关分析显示,医院文化多院区建设与多院区医疗服务、多院区党工团组织建设、多院区形象宣传和多院区人力分布具有相关性(P<0.01)且呈正相关。结论医院文化多院区建设相关研究逐渐火热,随着医院不断扩张,多院区文化建设还需加强党建引领,丰富文化建设形式,统筹学科规划,多院区同质化管理医疗质量,文化体系求同存异,建立统一品牌形象。

基于知识图谱的国内外儿童绘本可视化研究

目的利用科学知识图谱,对比分析国内外儿童绘本研究热点与趋势,总结出研究现存问题,提出未来研究展望。方法运用可视化文献分析软件Cite Space 6.2R1,选取中国知网数据中的北大核心、CSSCI、SCI期刊文献和Web of Science核心集合数据库中收录的儿童绘本相关文献作为研究对象,对当前国内外儿童绘本研究的发文量、发文作者、发文机构、研究热点、前沿与趋势等方面绘制科学知识图谱并进行可视化分析。结论国内外儿童绘本发文量均呈波动上升态势;国内发文作者、机构间合作不密切,国外合作密切且形成完整的合作团队;国内整体研究趋势侧重于绘本本身的创作、阅读、出版研究,国外侧重于儿童自身行为特点与成长发展的研究。国内外均存在缺少对儿童非认知能力内容研究、社会问题关联性领域研究、长期影响回顾方法研究等问题,且国内还存在缺乏对跨语言和跨文化的研究。未来展望于研究对象多样化、内容多元化、方法创新化、方向科技化,多维度提升儿童绘本研究的深度与广度。