面向动态任务合作求解的联盟模型

多Agent系统中,Agent间通过形成联盟达到提高任务求解能力,获取更多收益的目的。主要关注联盟模型的改进和联盟形成阶段的改进,基于ARG(agent,role,group)元模型和学习机制提出了一种采用角色和学习机制的新联盟模型CLAR(coalition model based on learnin gagent and role);在采用合同网协议的CLAR联盟模型中提出了两阶段联盟形成机制;通过捕食者问题实验验证了角色和学习机制的作用,以及两阶段联盟形成机制在减少通讯代价上的作用。     

面向电力传感器的环境能量收集技术发展趋势及面临的挑战

电力传感器作为能源互联网感知层的基本组成部分,其供电稳定性是广大从业者的关注重点。通过环境能量收集技术为传感器供电,可使传感器具有自供电特性以及长期免维护的优势,能量收集技术在电力传感领域的应用受到了越来越广泛关注。综述了环境能量收集技术在电力领域的应用现状以及温差、振动、风致振动等新型能量收集技术的特点。结合电力行业传感器应用需求,提出了环境能量收集技术在电力行业应用的发展趋势,总结为取能方式多样化、取能器件小型化和取能传感一体化等发展方向,并对应用发展面临的挑战进行了剖析,提出了取能技术应用面临的技术挑战、可靠性挑战和应用适配挑战。     

Hygroresponsive Torsional Yarns and Actuators Based on Cascade Amplification of the Deformation

Fiber-based hygroresponsive torsional actuators provide desirable merits, such as light weight and shapeability, for developing smart systems to harvest energy from moisture which is a ubiquitous natural resource. A key challenge in this development is to realize moisture-triggered actuation combining large actuation and rapid responses. Here, a multiscale design strategy is explored to create high-performance hygroresponsive torsional actuators consisting of chitosan and multiwalled carbon nanotubes (MWCNTs). The superior actuation performance arises from the synergism of contributing factors at different scales, including 1) MWNCTs accelerate the water transport in primary twisted fibers (PTFs), fostering the rotation of PTFs upon moisture stimuli; 2) in situ-formed hierarchically-assembled twists realize cascade amplification of moisture-triggered actuation. Specifically, PTFs are self-twisted to generate secondary helical yarns, that are subsequently over-twisted to yield tertiary coiled yarn. The resultant yarn actuator can reach a maximum rotation speed of 11 400 rpm in 5 s, output gravitational potential energy of 2.4 J kg⁻¹ and gravitational potential power of 0.053 W kg⁻¹ during contraction. This work represents the first design of fiber-based actuators by virtue of moisture-triggered in situ formation of yarns. The established principles of multiscale design will enable high-performance fiber-based hygroresponsive actuators toward advanced intelligent textile and soft robotics.     

基于变维卡尔曼滤波的UUV目标运动优化估计方法

为实现无人水下航行器精准、安全的跟踪目标从而高效地实现目标的信息采集,提出了一种针对该个体的目标运动优化估计方法。此方法通过建立目标运动模型,基于卡尔曼滤波基本原理,利用变维卡尔曼滤波的方法,达到UUV个体对目标运动状态准确估计的预期效果。为提高该方法的可行性,在利用最小化目标位置估计协方差矩阵完成目标运动轨迹估计及优化的过程中,考虑实际UUV机动时的最大速度限制、与目标最小距离的限制。文章详细阐述该方法的实现和步骤,并通过仿真实验验证了该优化算法的有效性。     

粒子群优化算法在关联规则挖掘中的研究综述

关联规则挖掘是数据挖掘中的重要领域,考虑到当前数据的大规模、高维度、模态多样及类型复杂等特性,传统关联规则挖掘算法已无法适应大数据的需求,粒子群优化算法作为一种高效的智能优化算法,为其提供了一种全新的解决方案,近年来被广泛应用于该领域。首先对粒子群优化算法的基本原理及关联规则的基本概念进行了详细介绍,回顾了粒子群优化算法的研究进展,分析了粒子群优化算法在关联规则挖掘中的研究,包括常用的数据转换方法、编码方式及评估指标,并与其他在关联规则挖掘中被广泛应用的算法进行了对比,总结了各自的优缺点及适用场景。然后对已有改进方法进行了较为系统的分类,即分为基于参数、基于变异机制和混合其他算法的改进。接着梳理归纳了粒子群优化算法在关联规则挖掘中的应用领域,阐述了该算法在购物篮、金融、医疗、工业生产及风险评估领域中的应用优势。最后在介绍这一领域的最新研究进展的基础上,通过对现存问题进行分析,讨论了进一步的研究方向。     

C-Shaped Cartilage Development Using Wharton's Jelly-Derived Hydrogels to Assemble a Highly Biomimetic Neotrachea for use in Circumferential Tracheal Reconstruction

A highly biomimetic neotrachea with C-shaped cartilage rings has promising clinical applications in the treatment of circumferential tracheal defects (CTDs) owing to its structure and physiological function. However, to date, most fabricated tracheal cartilages are O-shaped. In this study, finite element analysis demonstrates C-shaped cartilage rings that exhibit better compliance than O-shaped. Hydrogel is developed using methacryloyl-modified decellularized Wharton's jelly matrix (DWJMA) for the regeneration of C-shaped cartilage rings. This novel hydrogel possesses adjustable physicochemical properties and favorable cytocompatibility. When loaded with chondrocytes, DWJMA hydrogels support the optimal cartilage regeneration both in vitro and in vivo. More importantly, a highly biomimetic neotrachea simultaneously simulating the structural and physiological properties of the normal trachea is regenerated via modular assembly of several individual C-shaped cartilage rings. The results demonstrate the highly biomimetic neotrachea have better patency (88.6 ± 6.1% vs 74.4 ± 9.4%, p < 0.05), improve the survival rate, alleviate weight loss and mucoid impaction, than its O-shaped counterpart when used for the treatment of CTDs in a rabbit model. Therefore, this study proposes a novel hydrogel for the regeneration of C-shaped cartilage and provides new insights into the treatment of CTDs using a highly biomimetic neotrachea with C-shaped cartilage rings.     

Ultrasonic spray pyrolysis synthesis of Ag/TiO2 nanocomposite photocatalysts for simultaneous H2 production and CO2 reduction

Simultaneous photocatalytic hydrogen production and CO₂ reduction (to form CO and CH₄) from water using methanol as a hole scavenger were investigated using silver-modified TiO₂ (Ag/TiO₂) nanocomposite catalysts. A simple ultrasonic spray pyrolysis (SP) method was used to prepare mesoporous Ag/TiO₂ composite particles using TiO₂ (P25) and AgNO₃ as the precursors. The material properties and photocatalytic activities were compared with those prepared by a conventional wet-impregnation (WI) method. It was found that the samples prepared by the SP method had a larger specific surface area and a better dispersion of Ag nanoparticles on TiO₂ than those prepared by the WI method, and as a result, the SP samples showed much higher photocatalytic activities toward H₂ production and CO₂ reduction. The optimal Ag concentration on TiO₂ was found to be 2 wt%. The H₂ production rate of the 2% Ag/TiO₂–SP sample exhibited a six-fold enhancement compared with the 2% Ag/TiO₂–WI sample and a sixty-fold enhancement compared with bare TiO₂. The molar ratio of H₂ and CO in the final products can be tuned in the range from 2 to 10 by varying the reaction gas composition, suggesting a viable way of producing syngas (a mixture of H₂ and CO) from CO₂ and water using the prepared Ag/TiO₂ catalysts with energy input from the sun.     

Linking learning goals and educational resources through interactive concept map visualizations

Concept browsing interfaces can help educators and learners to locate and use learning resources that are aligned with recognized learning goals. The Strand Map Service enables users to navigate interactive visualizations of related learning goals and to request digital library resources aligned with learning goals. These interfaces are created using a programmatic Web service interface that dynamically generates interactive visual components. Preliminary findings suggest that these library interfaces appear to help users stay focused on the scientific content of their information discovery task, as opposed to focusing on the mechanics of searching.     

某坡屋盖文化综合体步行街连廊特殊防火设计探讨

在现代综合体建筑中火灾安全一直是全社会关注的焦点问题.一旦发生火灾重则会引起众多的人员伤亡.本文针对某特定文化艺术综合体步行街连廊部分,采用FDS模拟步行街连廊不同火源位置和不同外界环境等工况下,检验其步行街连廊能否作为室外安全区.经过模拟分析:除C1-1,C1-2工况外,连通步行街均满足人员疏散安全要求.对于C1-1,C1-2设置的是冬季工况,因为气温较低,空气浮力较小,大量烟气在层高为4 m纵向街道内蓄积沉降,走廊内烟气温度较高、烟气能见度较低,不利于疏散.另外与无风工况相比,有风工况下,更有利于烟气通过屋顶开敞部分排出室外.且模拟所有工况中,坡屋顶均未被引燃.理论计算表明,火灾对屋面影响不大,在模拟1800 s范围内,可认为步行街连廊安全,可认定为室外安全区.