An Efficient Optimization Design Framework for Low-Resistance Shape of Bionic Amphibious Robot

To realize the low-resistance shape optimization design of amphibious robots,an efficient optimization design framework is proposed to improve the geometric deformation flexibility and optimization efficiency.In the proposed framework,the free-form deformation parametric model of the flat slender body is established and an analytical calculation method for the height constraints is derived.CFD method is introduced to carry out the high-precision resistance calculation and a constrained Kriging-based optimization method is built to improve the optimization efficiency by circularly infilling the new sample points which satisfying the constraints.Finally,the shape of an amphibious robot example is optimized to get the low-resistance shape and the results demonstrate that the presented optimization design framework has the advantages of simplicity,flexibility and high efficiency.

Optimization of Center of Gravity Position and Anti-Wave Plate Angle of Amphibious Unmanned Vehicle Based on Orthogonal Experimental Method

When the amphibious vehicle navigates in water,the angle of the anti-wave plate and the position of the center of gravity greatly influence the navigation characteristics.In the relevant research on reducing the navigation resistance of amphibious vehicles by adjusting the angle of the anti-wave plate,there is a lack of scientific selection of parameters and reasonable research of simulation results by using mathematical methods,and the influence of the center of gravity position on navigation characteristics is not considered at the same time.To study the influence of the combinations of the angle of the anti-wave plate and the position of the center of gravity on the resistance reduction characteristics,a numerical calculation model of the amphibious unmanned vehicle was established by using the theory of computational fluid dynamics,and the experimental data verified the correctness of the numerical model.Based on this numerical model,the navigation characteristics of the amphibious unmanned vehicle were studied when the center of gravity was located at different positions,and the orthogonal experimental design method was used to optimize the parameters of the angle of the anti-wave plate and the position of the center of gravity.The results show that through the parameter optimization analysis based on the orthogonal experimental method,the combination of the optimal angle of the anti-wave plate and the position of the center of gravity is obtained.And the numerical simulation result of resistance is consistent with the predicted optimal solution.Compared with the maximum navigational resistance,the parameter optimization reduces the navigational resistance of the amphibious unmanned vehicle by 24%.

Air-Ground Collaborative Mobile Edge Computing:Architecture,Challenges,and Opportunities

By pushing computation,cache,and network control to the edge,mobile edge computing(MEC)is expected to play a leading role in fifth generation(5G)and future sixth generation(6G).Nevertheless,facing ubiquitous fast-growing computational demands,it is impossible for a single MEC paradigm to effectively support high-quality intelligent services at end user equipments(UEs).To address this issue,we propose an air-ground collaborative MEC(AGCMEC)architecture in this article.The proposed AGCMEC integrates all potentially available MEC servers within air and ground in the envisioned 6G,by a variety of collaborative ways to provide computation services at their best for UEs.Firstly,we introduce the AGC-MEC architecture and elaborate three typical use cases.Then,we discuss four main challenges in the AGC-MEC as well as their potential solutions.Next,we conduct a case study of collaborative service placement for AGC-MEC to validate the effectiveness of the proposed collaborative service placement strategy.Finally,we highlight several potential research directions of the AGC-MEC.

Optimized air-ground data fusion method for mine slope modeling

Refined 3D modeling of mine slopes is pivotal for precise prediction of geological hazards.Aiming at the inadequacy of existing single modeling methods in comprehensively representing the overall and localized characteristics of mining slopes,this study introduces a new method that fuses model data from Unmanned aerial vehicles(UAV)tilt photogrammetry and 3D laser scanning through a data alignment algorithm based on control points.First,the mini batch K-Medoids algorithm is utilized to cluster the point cloud data from ground 3D laser scanning.Then,the elbow rule is applied to determine the optimal cluster number(K0),and the feature points are extracted.Next,the nearest neighbor point algorithm is employed to match the feature points obtained from UAV tilt photogrammetry,and the internal point coordinates are adjusted through the distanceweighted average to construct a 3D model.Finally,by integrating an engineering case study,the K0 value is determined to be 8,with a matching accuracy between the two model datasets ranging from 0.0669 to 1.0373 mm.Therefore,compared with the modeling method utilizing K-medoids clustering algorithm,the new modeling method significantly enhances the computational efficiency,the accuracy of selecting the optimal number of feature points in 3D laser scanning,and the precision of the 3D model derived from UAV tilt photogrammetry.This method provides a research foundation for constructing mine slope model.

Preparation and Conducting Behavior of Amphibious Organic/Inorganic Hybrid Proton Exchange Membranes Based on Benzyltetrazole

A series of novel amphibious organic/inorganic hybrid proton exchange membranes with H3PO4 doped which could be used under both wet and dry conditions was prepared through a sol-gel process based on acrylated triethoxysilane（A-TES） and benzyltetrazole-modified triethoxysilane（BT-TES）.The dual-curing approach including UV-curing and thermal curing was used to obtain the crosslinked membranes.Polyethylene glycol（400） diacrylate（PEGDA） was used as an oligomer to form the polymeric matrix.The molecular structures of precursors were characterized by 1 H,13 C and 29 Si NMR spectra.The thermogravimetric analysis（TGA） results show that the membranes exhibit acceptable thermal stability for their application at above 200 oC.The differential scanning calorimeter（DSC） determination indicates that the crosslinked membranes with the mass ratios of below 1.6 of BT-TES to A-TES and the same mass of H3PO4 doped as that of A-TES possess the-T g s,and the lowest T g（-28.9 ℃） exists for the membrane with double mass of H3PO4 doped as well.The high proton conductivity in a range of 9.4―17.3 mS/cm with the corresponding water uptake of 19.1%―32.8% of the membranes was detected at 90 oC under wet conditions.Meanwhile,the proton conductivity in a dry environment for the membrane with a mass ratio of 2.4 of BT-TES to A-TES and double H3PO4 loading increases from 4.89×10-2 mS/cm at 30 ℃ to 25.7 mS/cm at 140 ℃.The excellent proton transport ability under both hydrous and anhydrous conditions demonstrates a potential application in the polymer electrolyte membrane fuel cells.

Hydrodynamics Research on Amphibious Vehicle Systems:Modeling Theory

For completing the hydrodynamics software development and the engineering application research on the amphibious vehicle systems, hydrodynamic modeling theory of the amphibious vehicle systems is elaborated, which includes to build up the dynamic system model of amphibious vehicle motion on water, gun tracking-aiming-firing, bullet hit and armored check-target, gunner operating control, and the simulation computed model of time domain for random sea wave.

应用于水陆两栖勘测及紧急救援的仿生机械龟

针对现有水下航行器能耗高、噪声大、续航能力一般等问题,通过探索水下仿生扑翼的推进机理,结合流体力学运动的知识,利用SolidWorks仿造龟的外形设计了仿生机械龟。该机械龟装载浮力与重力感应系统,通过PID算法控制机器在水中的平衡,使用Arduino作为主控制板,利用传感器、摄像系统与数据传输系统,进行实时监测并传输数据,龟壳中设计了贮藏空间,满足勘测和物资救援任务。实验结果表明,所设计的水陆两栖仿生机械龟优化了形态和运行控制系统,对比美国耶鲁大学研制出的仿乌龟形水陆两栖机器人ART,能够适应多样化地形高效的运动,具有高灵活性和机动性,能完成对水中温度、压强、地形进行实时监测并将数据传输回终端。

水陆两栖车辆水上运动特性实时仿真系统研究

为解决水陆两栖车辆水动力性能参数获取难度大、运动姿态预测慢等问题,设计一种两栖车辆水上运动特性实时仿真系统,实现仿真模型的驱动、运动姿态预测以及数据的监测和输出,通过动态流体-物体相互作用数值计算方法对车体动力学系数进行修正,提升了实时仿真系统的精度。在此基础上研制试验样车,对不同工况下实时仿真系统的准确性进行验证。试验结果表明:所构建的两栖车辆水上运动特性实时仿真系统兼具计算精度和计算效率,可以快速准确地预测车辆的运动姿态,适用于多种复杂工况,具有姿态预测的泛用性。新系统在两栖车辆研制阶段、驾驶员培训、半实物仿真演练、复杂环境模拟等方面具有较强的应用价值和应用前景。

基于计算流体动力学方法的两栖飞机规则波中运动特性研究

针对水陆两栖飞机加速起飞运动过程受波浪干扰问题,本文基于Star-CCM+平台数值模拟技术,引入SST k-ε湍流模型求解RANS方程,VOF方法捕捉自由液面,DFBI模块以及重叠网格技术模拟水上飞机六自由度运动,建立了一套波浪中水陆两栖飞机加速滑行起飞运动特性研究方案。以波长和波高为变量,探讨了加速滑行过程中上述变量对水上飞机升沉、纵摇运动响应以及机身重心处垂向加速度的影响规律。结果表明:随着波长增加,飞机升沉运动先增加后缓慢变化,飞机重心垂向加速度、纵摇角加速度和纵摇峰值集中在波长为2~3倍机身长度海况范围内;随着波高增大,飞机升沉、纵摇运动及重心垂向加速度最大值随之增大,且长波中的运动变化量较短波中更大;机翼气动升力数值模拟结果与计算值一致,该方案可用于水陆两栖飞机气动力相关计算。

两栖攻击舰编队海上航渡对潜防御队形优化配置研究

针对两栖攻击舰编队对潜防御时的队形配置问题,从潜艇对编队的威胁分析入手,建立了潜艇鱼雷极限射距圆模型,通过模型分析与仿真计算,得出了两栖攻击舰应配置在威胁圆圆心稍后位置的结论,并给出了优化位置计算模型;结合潜艇威胁范围与威胁距离模型及警戒舰艇对潜防御范围模型,给出了护航兵力优化配置方法,为两栖攻击舰编队海上航渡时的对潜防御提供了参考。

基于模糊PID的球形两栖机器人的设计及控制

为了解决移动机器人对工作环境要求严格的问题,设计了一种适用于多变、狭窄环境的轻小型球形陆空两栖机器人,具有地面滚动和空中飞行两种运动模式,可以自主完成运动模式的切换。首先,设计了机器人的结构,包括滚动部分、飞行部分和模式切换部分。基于拉格朗日方法,建立了不同运动模式下的动力学模型,建立了基于欧拉方程的运动学模型。最后,根据机器人的运动模型,设计了飞行模式和地面滚动模式下的姿态控制器,并对控制器进行了仿真对比实验。在实机上进行了测试,实验结果表明,该机器人能够实现自主模式切换,在不同运动模式下运动稳定、姿态可控,在纯地面模式下具有一定的越障能力。在结构、控制方法及控制策略切换方法上对陆空两栖可变形机器人具有一定借鉴作用。

两栖植物香附子的解剖结构和组织化学研究

以分布在三峡水库消落区和江汉平原河漫滩香附子营养器官为试验材料,采用解剖镜下切片法、组织化学研究方法、光学和荧光显微镜下观察拍照记录试验结果,研究其叶、直立茎、根状茎、块茎和不定根适应两栖环境的解剖结构与组织化学特征。结果表明:1)香附子具有适应两栖环境的气腔和质外体屏障等典型结构特征,其中气腔包含根、根状茎及叶的溶生性通气组织和茎的裂生性通气组织;质外体屏障包括内皮层、外皮层、栓质化中柱和维管束鞘细胞等。2)香附子的不定根和茎具有栓质化中柱和维管束;叶片和茎的花环结构由内侧维管束鞘、中间维管束鞘和薄壁细胞维管束鞘3层组成。3)香附子的质外体屏障可能有助于香附子在淹没缺氧下保持氧气流通,同时控制水、离子与环境交换,气腔有利于保存和输送有氧呼吸所必需的氧气。香附子适应淹没-陆生两栖转换环境的结构特征表明其是长江流域生态恢复的重要植物资源。

基于神经网络算法的水陆两栖无人艇控制系统研究

针对近海登陆两栖作战等不适合士兵冲锋陷阵的高危环境,提出了基于神经网络算法的水陆两栖无人艇控制系统研究,伺服运动控制为控制系统的关键核心之一。鉴于目前传统两栖无人艇运动控制系统PID算法控制精度低、误差大、需人工调节参数等缺陷,提出BP-PID神经网络算法,同时融合GWO算法(灰狼算法),利用其搜索能力优化网络权值和阈值,加快网络收敛,提高控制精度。首先,对水陆两栖无人艇的控制系统进行需求分析,继而完成两栖无人艇伺服运行控制系统数学和控制模型设计、神经网络算法构架等设计,将设计的算法引入两栖无人艇运动控制系统中,并且进行实验验证,得到行驶曲线。结果表明控制系统运行稳定、响应速度快、误差小,行驶轨迹精确等优点。为实现不适合士兵直达近海登陆作战高危未知环境提升作战力,保护士兵安全有很重要现实意义和实用工程价值,为未来武器装备的智能化研究发展提供借鉴。

基于图搜索的陆空两栖平台3D路径规划算法

为了解决陆空两栖平台路径规划能效与寻径效率问题,提出了一种基于图搜索算法的全局路径规划算法。考虑了空中飞行能耗与地面行驶能耗模型的不同,结合起飞阈值、地面移动成本系数、空中移动成本系数等参数决定模态切换机制,在遇到难以越过的障碍时使用逃脱算法脱困,当允许地面通过时优先采用地面行驶的方式到达目标点以提升寻径效率与能效。为验证该算法,分别建立了针对陆空2种模式下的能耗模型,在现有交通规则约束下完成城市场景和虚拟迷宫测试。结果表明:本算法的搜索效率相较于对照组算法提升了30%以上,有效提升搜寻效率的同时降低了能量消耗。

不同结构炮口制退器对某两栖火炮底盘影响分析

为研究不同结构炮口制退器对两栖火炮炮口流场影响,采用CFD技术,结合动网格技术对弹丸进行处理,采用三维非定常可压缩流动的Euler方程和Realizable k-ε湍流方程对炮口流场进行数值模拟。通过数值仿真得到了炮口流场对车体不同部位的超压分布规律,结果表明,在冲击式炮口制退器下舱盖前端面上棱位置横向压力,与舱盖前端面下棱横向压力均比反冲击式的压力高。在炮口下方位置车体上表面横向位置,t=1.0 ms左右,在冲击式炮口制退器下的超压值比反冲击式高约为0.8 MPa。研究结果对两栖火炮炮口底盘相关设计、制退器结构选择提供了数据依据。

两栖车辆发动机增压匹配及控制策略研究

针对两栖车辆在水陆工况下的功率需求,开展车辆在两种工况下的动力系统增压匹配及控制策略研究。建立了车用发动机在两种工况条件下的一维仿真模型,对增压器、放气阀等关键部件进行了标定,并对整机仿真模型进行了实验验证。以此模型为基础完成了两种工况条件下的增压系统匹配,研究两栖工况下的增压发动机输出特性,制定两种工况下的废气旁通阀开度控制策略。结果表明,计算匹配的增压器和控制策略满足两栖车辆在不同工况下的功率需求。

基于CFD的轮式两栖车减阻方案研究

文中针对将两栖车车轮收起但未达到全封闭状态,存在开口时的几何结构,提出了不同的改型减阻方案.基于CFD软件STAR-CCM+,采用重叠网格技术构建数值模型.根据国际拖曳水池会议(ITTC)的不确定度分析规程进行数值不确定度分析,计算每种方案的阻力、纵倾,以及升沉数据,并与原车方案的数据进行对比.结果显示:数值的不确定度满足UV>E,表明数值模拟在UV层次上得到确认.结果表明:对两栖车不同轮桥位增加挡板,对其减阻效果和运动姿态的影响差异较大;减阻率最高可达25.4%;纵倾角变化幅度在1.8%~32.8%,对两栖车升沉状态影响较大.

3D interlocked all-textile structured triboelectric pressure sensor for accurately measuring epidermal pulse waves in amphibious environments

The performance degradation and even damage of the e-textiles caused by sweat,water,or submersion during all-weather health monitoring are the main reasons that e-textiles have not been commercialized and routinized so far.Herein,we developed an amphibious,high-performance,air-permeable,and comfortable all-textile triboelectric sensor for continuous and precise measurement of epidermal pulse waves during full-day activities.Based on the principle of preparing gas by acid-base neutralization reaction,a one-piece preparation process of amphibious conductive yarn(ACY)with densely porous structures is proposed.An innovative three-dimensional(3D)interlocking fabric knitted from ACYs(0.6 mm in diameter)and polytetrafluoroethylene yarns exhibit high sensitivity(0.433 V·kPa^(-1)),wide bandwidth(up to 10 Hz),and stability(>30,000 cycles).With these benefits,98.8%agreement was achieved between wrist pulse waves acquired by the sensor and a high-precision laser vibrometer.Furthermore,the polytetrafluoroethylene yarn with good compression resilience provides sufficient mechanical support for the contact separation of the ACYs.Meanwhile,the unique skeletonized design of the 3D interlocking structure can effectively relieve the water pressure on the sensor surface to obtain stable and accurate pulse waves(underwater depth of 5 cm).This achievement represents an important step in improving the practicality of e-textiles and early diagnosis of cardiovascular diseases.

水陆两栖飞机内流场结构冲击响应特性

水陆两栖飞机在航空消防领域具有独特优势,但其在水面高速滑行汲水和空中飞行灭火投水过程中,机体内部的运动水流会带来非定常水冲击效应。对于飞行器的流固耦合问题,以往的研究主要集中于机体外围流场与刚性飞机的相互作用,极少关注内部流场对结构变形和应力分布的影响。为此,根据水陆两栖飞机的使用模式,采用光滑粒子流与结构有限元耦合仿真的方法,开展全机主要影响区域的结构有限元建模和内流场建模,利用流固耦合方式求解机体弹性结构在汲水和投水内流场作用下的动态应力分布。结果表明:飞机高速汲水过程中,箱体结构持续受到内流冲击激励,结构各部位的应力不断变化,部分区域出现应力幅值较大幅度的振荡变化,且水箱隔板在某些时刻的最大瞬态应力达到0.38σ_(b),最大振幅为0.42σ_(max);飞机采用重力方式空中投水时,箱体结构受到的内流冲击激励相对较弱,端框最大瞬态增量应力为0.15σ_(b),最大振幅为0.22σ_(max),结构增量应力水平不高,且应力振荡幅度较小。

网格运动方式对水陆两栖飞机单船身阻力计算影响

为提高水陆两栖飞机滑水阻力计算精度,基于黏性CFD计算软件STAR-CCM+,分别采用整体动网格法、常规动网格方法、重叠网格方法3种不同的网格运动方式对单船身模型开展静水面滑行数值仿真,对比分析了网格运动方式对船底水气分布、兴波形状及阻力数值预报的影响特点,并与模型试验结果进行比较,验证不同方法的精度,结果表明,在排水航行和滑行状态下,3种不同网格运动方式计算得到的阻力差异较小,且与试验值较为接近,而在过渡滑行阶段,不同网格运动方式计算得到的阻力值之间差异较大,其中,整体动网格法的计算结果与试验值误差较小,说明整体动网格法更适用于水陆两栖飞机单船身滑水阻力性能的计算。