Biological Jumping Mechanism Analysis and Modeling for Frog Robot

This paper presents a mechanical model of jumping robot based on the biological mechanism analysis of frog. By biological observation and kinematic analysis the frog jump is divided into take-offphase, aerial phase and landing phase. We find the similar trajectories of hindlimb joints during jump, the important effect of foot during take-off and the role of forelimb in supporting the body. Based on the observation, the frog jump is simplified and a mechanical model is put forward. The robot leg is represented by a 4-bar spring/linkage mechanism model, which has three Degrees of Freedom （DOF） at hip joint and one DOF （passive） at tarsometatarsal joint on the foot. The shoulder and elbow joints each has one DOF for the balancing function of arm. The ground reaction force of the model is analyzed and compared with that of frog during take-off. The results show that the model has the same advantages of low likelihood of premature lift-off and high efficiency as the frog. Analysis results and the model can be employed to develop and control a robot capable of mimicking the jumping behavior of frog.

ON THE STRAIN JUMP IN SHAPE MEMORY ALLOYS—A CRYSTALLOGRAPHIC-BASED MECHANICS ANALYSIS

The strain jump across the Austenite-Martensite (A-M) interface in single crystal Cu-14wt%Al-4.12wt%Ni Shape Memory Alloys (SMAs) under uniaxial tension was studied in this paper. A crystallographic-based mechanics analysis on the formation and microstructure of the interface was performed. By using the high sensitive Moiré interference technique, the full-field deformation patterns during the transformation process were successfully recorded. The orientation of the habit plane (A-M interface) and the magnitude of the shape strain were determined precisely from the Moiré fringe patterns. The theoretical predictions on the habit plane normal and the shape strain were compared with the measured results and good agreements were obtained.

Investigation of earthquake mechanisms and their impact on certain basic concepts in earthquake engineering and seismology

In this paper, mantle circulation flow, continental drift, earthquake origin and other mechanical principles are examined as they apply to earthquake engineering, seismology and dynamics of fluid saturated porous medium. The relationship of mantle flow to earthquakes is examined and clarified, and a new model, different from Haskell’s, is proposed for the earthquake mechanism. The proposed new model is based on the discovery that two pairs of jump stress and jump velocity will start to act from the fault plane. Records obtained directly from recent earthquakes nearby and right on the fault break show a very large velocity impulse, which verify, indirectly, the new mechanism proposed by the author. Further, at least two physical parameters that characterize the seismic intensity must be specified, because according to the discontinuous (jump) wave theory, at the earthquake source, the stress jump and the velocity jump of particle motion should act simultaneously when a sudden break occurs. The third key parameter is shown to be the break (fracture) propagation speed together with the break plane area. This parameter influences the form of the unloading time function at the source. The maximum seismic stress in and displacement of a building are estimated for two unfavorable combinations of the building and its base ground in terms of their relative rigidity. Finally, it is shown that Biot’s theory of wave propagation in fluid saturated porous media is valid only when fluid flow cannot occur.

基于Jump-SBERT的二进制代码相似性检测技术研究

二进制代码相似性检测技术在不同的安全领域中有着重要的作用。针对现有的二进制代码相似性检测方法面临计算开销大且精度低、二进制函数语义信息识别不全面和评估数据集单一等问题,提出了一种基于Jump-SBERT的二进制代码相似性检测技术。Jump-SBERT有两个主要创新点,一是利用孪生网络构建SBERT网络结构,该网络结构能够在降低模型的计算开销的同时保持计算精度不变;二是引入了跳转识别机制,使Jump-SBERT可以学习到二进制函数的图结构信息,从而更加全面地捕获二进制函数的语义信息。实验结果表明,Jump-SBERT在小函数池(32个函数)中的识别准确率可达96.3%,在大函数池(10000个函数)中的识别准确率可达85.1%,比最先进(State-of-the-Art,SOTA)的方法高出36.13%,且Jump-SBERT在大规模二进制代码相似性检测中的表现更加稳定。消融实验表明,两个主要创新点对Jump-SBERT均有积极作用,其中,跳转识别机制的贡献最高可达9.11%。

A Double Sensitive Fault Detection Filter for Positive Markovian Jump Systems With A Hybrid Event-Triggered Mechanism

This paper is concerned with the double sensitive fault detection filter for positive Markovian jump systems. A new hybrid adaptive event-triggered mechanism is proposed by introducing a non-monotonic adaptive law. A linear adaptive event-triggered threshold is established by virtue of 1-norm inequality.Under such a triggering strategy, the original system can be transformed into an interval uncertain system. By using a stochastic copositive Lyapunov function, an asynchronous fault detection filter is designed for positive Markovian jump systems(PMJSs) in terms of linear programming. The presented filter satisfies both L_-gain(?_-gain) fault sensitivity and L_1(?_1)internal differential privacy sensitivity. The proposed approach is also extended to the discrete-time case. Finally, two examples are provided to illustrate the effectiveness of the proposed design.

T-JUMP/FTIR联用技术研究RDX的热裂解过程

用T-JUMP/FTIR技术研究了模拟燃烧条件下RDX的热裂解过程。通过分析裂解产物随时间的分布规律及温度与压力对裂解过程的影响,提出了RDX可能的快速热裂解机理及影响快速热裂解机理的因素。结果表明,RDX裂解气相产物主要有CO2、N2O、NO2、HNCO、NO、CO和HCN,且在不同的测试条件下产物的相对含量有明显变化:在600℃、0.1～0.4MPa条件下,裂解5s以内的NO2与NCN含量比随压力的升高而下降;HCN与N2O含量比随压力的提高而增大;在0.1MPa压力条件下,随着温度的升高,HCN与N2O的含量比趋向于增大。RDX快速热裂解的初期存在两个竞争反应,即C—N和N—N键的断链竞争反应;提高温度和在0.1～0.4MPa压力范围内提高压力对生成HCN的N-N键断裂反应有利。

Design and Demonstration of a Locust-Like Jumping Mechanism for Small-Scale Robots

A jumping mechanism can be an efficient mode of motion for small robots to overcome large obstacles on the ground and rough terrain. In this paper, we present a 7 g prototype of locust-inspired jumping mechanism that uses springs, wire, reduction gears, and a motor as the actuation components. The leg structure and muscles of a locust or grasshopper were mimicked using springs and wire, springs for passive extensor muscles, and a wire as a flexor muscle. A small motor was used to slowly charge the spring through a lever and gear system, and a cam with a special profile was used as a clicking mechanism for quick release of elastic energy stored in the springs to create a sudden kick for a quick jump. Performance analysis and experiments were conducted for comparison and performance estimation of the jumping mechanism prototype. Our prototype could produce standing jumps over obstacles that were about 14 times its own size （approximate to 71 cm） and a jumping distance of 20 times its own size （approximate to 100 cm）.

A Single-legged Robot Inspired by the Jumping Mechanism of Click Beetles and Its Hopping Dynamics Analysis

The click beetle can jump up with a hinge when it is on the dorsal side.This jumping mechanism is simple and suitable as an inspiration for designing a simple,small,and reliable hopping robot.We report a single-legged robot inspired by the jumping mechanism of click beetles.It is 85 mm high,60 mm long,and 41 mm wide,and weighs about 49 g.The robot has good hopping performance that the hopping height is about 4 times-4.3 times of its body height.It is capable for rescue missions that require to enter enclosed spaces through cracks and narrow channels.In addition,hopping dynamics of the robot is important to understand its jumping mechanism and improve the robot’s hopping performance.But existing dynamic study does not complete the analysis including all stages in the hopping which are pre-hopping,take-off,and air-flying.We propose the decomposition method to study dynamics of the three stages separately,and synthesize them with related parameters.The dynamic synthesis of multi-motion states in a hopping cycle of the single-legged hopping robot is implemented.The hopping performance and dynamic synthesis theory of the robot are verified by simulations and experiments.Our study helps lay the foundation for design and hopping control of simple hopping robot systems.

Wheeled jumping robot by powermodulation using twisted string lever mechanism

This study introduces a wheeled robot platform with jumping ability.To realize jump movement,a twisted string lever mechanism is used,which is characterized by its compactness and variable gear ratio.Based on robot modeling and parameter calculation,the twisted string actuator shows its advantage when applied to situations such as jumping of robots,where explosiveness of output force matters.In this study,a wheeled bipedal robot equipped with the twisted string actuator is designed and fabricated.It weighs 16.0 kg and can perform jumps when it encounters obstacles.The prototype can jump up to a stage with a maximum height of 1.0 m using electric power,which is approximately 1.5 times the height of its stretched legs.

深度复数轴向自注意力卷积循环网络的语音增强

单通道语音增强任务中相位估计不准确会导致增强语音的质量较差,针对这一问题,提出了一种基于深度复数轴向自注意力卷积循环网络(deep complex axial self-attention convolutional recurrent network,DCACRN)的语音增强方法,在复数域同时实现了语音幅度信息和相位信息的增强.首先使用基于复数卷积网络的编码器从输入语音信号中提取复数表示的特征,并引入卷积跳连模块用以将特征映射到高维空间进行特征融合,加强信息间的交互和梯度的流动.然后设计了基于轴向自注意力机制的编码器-解码器结构,利用轴向自注意力机制来增强模型的时序建模能力和特征提取能力.最后通过解码器实现对语音信号的重构,同时利用混合损失函数优化网络模型,提升增强语音信号的质量.实验在公开数据集Valentini和DNS Challenge上进行,结果表明所提方法相对于其他模型在客观语音质量评估(perceptual evaluation of speech quality,PESQ)和短时客观可懂度(short-time objective intelligibility,STOI)两项指标上均有提升,在非混响数据集中,PESQ比DCTCRN(deep cosine transform convolutional recurrent network)提高了12.8%,比DCCRN(deep complex convolutional recurrent network)提高了3.9%,验证了该网络模型在语音增强任务中的有效性.

跳台雪板仿生点阵结构优化设计

通过借鉴自然界中毛竹的截面微观结构特征,设计了一种应用于跳台雪板内的仿生点阵结构,并基于响应面方法进行了优化设计。通过数值仿真模拟准静态压缩和三点弯曲实验,探究了仿生点阵结构的承载与抗弯性能。研究仿生点阵结构的单胞胞体壁厚、柱状结构的半径和壁厚3个几何参数对其力学性能的影响规律,并运用主次影响分析方法探究不同几何参数对力学性能的影响程度。建立了以比刚度、比弯曲刚度最大为目标,以单胞几何尺寸为约束的优化模型,并采用非支配排序遗传算法进行计算求解,得到Pareto前沿最优解,经数值仿真验证仿生点阵结构抗弯承载性能显著优于雪板内原始点阵格栅结构以及其余2种点阵格栅结构。研究结果对于跳台雪板内填充点阵格栅结构的仿生设计以及雪板整体力学性能的提升具有重要意义。

自适应事件触发机制下分布时滞Markov跳变网络化系统H_(∞)故障检测

传统事件触发机制中阈值的选择会对信号传输效率产生很大影响。针对此问题,研究了自适应事件触发机制下具有分布时滞的Markov网络化系统的故障检测问题。设计了一种模态相关的自适应事件触发机制,通过动态调整阈值,提高了网络资源利用率。考虑网络时延和数据丢包现象,同步设计触发器和故障检测滤波器。构造模态相关的Lyapunov泛数,根据积分不等式技术推导出使系统随机稳定且具有H_(∞)性能的充分条件。利用解耦方法和LMI技术求解出了故障检测滤波器参数。最后通过数值仿真验证了方案在节省网络资源上的优势。

结合信誉跳跃一致性哈希的区块链分片协议

区块链面临扩展性问题,目前主要的解决方法是采用分片技术提升交易的处理能力,但分片过后单个分片内节点数量降低,容易造成分片内中心化与拜占庭节点聚集,对网络的安全性产生危害。针对此问题,提出了一个结合信誉跳跃一致性哈希的区块链分片协议。设计了一种节点信誉等级模型,通过节点在网络中的行为赋予节点不同的信誉等级,降低拜占庭节点在网络中的话语权;提出了基于信誉的跳跃一致性哈希分片部分重构算法(reputation-based jump consistent hash sharding partial reconstruction,RJSPR),将信誉值作为节点进行分片重配置的重要考量,减少分片迁移的开销,并且有效提升分片后的网络安全性;提出了一种基于信誉的改进Raft共识算法(reputation-enhanced Raft,RERaft)用于片内共识,使其拥有一定程度的拜占庭容错能力。实验结果表明,RERaft算法在具备一定拜占庭容错能力的同时可以有效提升系统的共识效率,相比于常见的拜占庭容错算法,具有更好的可扩展性。

基于EACN模型的高精度测温误差修正算法

针对红外热像仪测温精度不足以及速度较慢的问题,提出了一种融合通道注意力机制的温度修正模型EACN(Efficient Attention Compression Networks Module)。该模型首先通过1×1卷积实现特征降维压缩,以此减少模型参数。其次引入通道注意力机制ECA,在特征映射模块阶段增强通道间特征显著性表达,以此弥补降维压缩所损失的特征信息,且进一步提高模型特征表征能力。最后,通过跳跃连接,在特征重建阶段结合浅层特征信息与语义空间信息,从而提高温度修正精度。本实验采用两种数据策略在自建数据集上进行实验。实验结果表明,与SRCNN和VDSR模型相比,EACN模型无论在修正精度方面,还是速度方面表现均最优。

改进YOLOv5的多人姿态估计修正算法

由于拥挤场景中的多人姿态估计仍受检测目标较小等问题的影响,导致姿态估计准确率低,为此提出一种改进YOLOv5的多人姿态估计修正算法。首先,在YOLOv5的骨干网络中,融入跳跃注意力模块,帮助网络在图像中找到感兴趣区域;其次,在颈部网络中,利用加权双向特征金字塔提高网络对不同尺度特征图间的特征融合能力,并联合使用跳跃注意力模块与Transformer编码器,使网络获取全局信息和丰富的上下文信息;再次,在检测部分增加一个检测头,使网络对微小目标更加敏感;最后,利用网络预测得到的关键点对象信息修正姿态对象信息得到最终的多人姿态估计结果。实验结果表明,本文算法较YOLOv5在COCO数据集上AP 50提高了2.2%,AP 75提高了3.3%,验证了本文算法的精确性和鲁棒性。

Finite-time decentralized event-triggered state estimation for coupled neural networks under unreliable Markovian network against mixed cyberattacks

This article investigates the issue of finite-time state estimation in coupled neural networks under random mixed cyberattacks,in which the Markov process is used to model the mixed cyberattacks.To optimize the utilization of channel resources,a decentralized event-triggered mechanism is adopted during the information transmission.By establishing the augmentation system and constructing the Lyapunov function,sufficient conditions are obtained for the system to be finite-time bounded and satisfy the H∞ performance index.Then,under these conditions,a suitable state estimator gain is obtained.Finally,the feasibility of the method is verified by a given illustrative example.

仿青蛙跳跃机器人虚拟样机的机构设计

跳跃式机器人相比轮动式机器人的主要优点是能更灵活的运动以适应更多陡峭地形,我们以青蛙为原型设计了一种仿生跳跃型机器人,能够完成侦探、探索地形等任务。结合青蛙跳跃前后各个阶段的运动需要在前后肢体运动形态,足部结构设计和动力系统上都采取了创新设计,并在机械设计的基础上虚拟样机建模,以进行Adams仿真方法与运动学分析进行跳跃可行性验证,为后续机器人制造过程打下基础。

多策略鼠群优化算法的无人机三维航迹规划

针对在复杂电力检测环境中无人机三维航迹规划问题,提出一种基于跳跃式自适应小孔成像反向学习鼠群优化(JAPRSO)算法的无人机三维航迹规划方法。JAPRSO算法引入了Sobol序列初始化种群以增强种群多样性;引入了非线性自适应因子实现动态权衡局部开发和全局搜索能力;嵌入了跳跃式围捕猎物机制以避免算法陷入局部最优;同时,引入跳跃式自适应小孔成像反向学习追赶猎物机制以提高算法的全局寻优能力。仿真结果表明:所提出的路径规划方法寻优性能优于RSO算法、灰狼优化(GWO)算法,金枪鱼群优化(TSO)算法和海鸥优化(SOA)算法,能够有效地躲避威胁区,快速获得航迹代价最小的安全可行航迹,可适用于求解电力检测方面的无人机三维航迹规划问题。

降雨诱发堆积体浅层破坏特征及机理研究

降雨诱发的堆积体滑坡广泛分布于三峡库区,通过研究此类滑坡的变形特征及失稳机制,分析其稳定性,对滑坡灾害的治理有重要意义。以桥头北次级滑坡为例,综合分析降雨、自动GNSS监测等数据,结合野外宏观巡查及勘查资料,研究了其变形特征及失稳机理。结果表明,桥头北次级滑坡整体变形明显,累积位移-时间关系曲线呈“阶跃”变形特征,降雨及因挡土墙排水失效导致的坡体饱和及地表漫流是诱发滑坡变形的主要因素,降雨通过孔隙和地表裂缝渗入坡体,地下水位抬升,积聚1~2 d后坡体饱和,变形加速开始,降雨结束3~7 d后恢复。

欺骗攻击下奇异跳变系统状态感知事件触发H_(∞)-脉冲混杂反馈控制

本文研究了在欺骗攻击下奇异马尔可夫跳变系统的状态感知事件触发H_(∞)-脉冲混杂反馈控制问题。为了进一步权衡控制性能和通信效率,提出了一种可根据当前系统状态自适应地调整事件触发阈值的基于周期采样的模态相关状态感知事件触发机制。基于所提出的事件触发机制,建立了一种模态相关的脉冲混杂反馈控制器。通过构造脉冲时间相关和马尔可夫跳变模态相关的Lyapunov-Krasovskii(L-K)泛函并结合奇异值分解技术,获得了奇异马尔可夫跳变系统在欺骗攻击下的H_(∞)随机容许性准则。在线性矩阵不等式框架下实现了状态感知事件触发器和H_(∞)-脉冲混杂反馈控制器协同设计。直流电机驱动负载的仿真实例验证了本文方法的有效性。