For high-precision attitude adjustment tasks of a six-degree-of-freedom (6-DOF) wave-compensation parallel robot in shipborne applications, strong non-stationary wave excitations, abrupt load changes, and broadband disturbances jointly challenge tracking accuracy and smoothness. To address these challenges, this paper proposes a tuna swarm optimization (TSO)-tuned triple-loop Fractional-Order PI control strategy (TSO-FOPI). The proposed approach combines TSO-based offline parameter tuning with a triple-loop FOPI control structure to improve compensation accuracy and robustness, and a closed-loop stability analysis is provided. Power spectral density analysis under swept-frequency excitation indicates that TSO-FOPI effectively suppresses residual vibrations of the robot in the dominant wave-frequency band and achieves better wideband disturbance rejection against injected high-frequency perturbations. Furthermore, under random wave excitation corresponding to sea state 4, the proposed control strategy reduces the overall compensation error by about 59% and 36.4% compared with PI and FOPI controllers, respectively, and improves the overall compensation smoothness by about 65% and 30.25%. In summary, the proposed method shows potential for engineering implementation for high-precision motion control of 6-DOF wave-compensation parallel robots and onboard precision equipment in disturbance-intensive environments.

Developing high-performance wearable flexible sensors that can adapt well to complex environments has become a hotspot. Herein, a polyvinyl alcohol based composite hydrogel sensor with high mechanical strength, desirable frost/swelling resistance, and highly sensitive sensing performance was proposed by a multi-component collaborative design strategy. Meanwhile, an intelligent gesture recognition system was established by combining machine learning algorithm. With the synergistic effect of aramid nanofibers and polyaniline, a composite skeleton coupled with a rigid network and a hydrogen bond network was constructed in the hydrogel, and its phase transition behavior was regulated by a mixed solvent system of glycerol/water. The composite hydrogel sensor exhibited excellent mechanical properties (tensile strength: 2.22 MPa, toughness: 3.58 MJ/m3), good environmental adaptability (low-temperature resistance of -30 °C, swelling rate < 15 % after 20 days), and good sensitivity (gauge factor: 1.41). Furthermore, high-precision recognition of different gestures (accuracy close to 100 %) could be achieved by collecting dynamic resistance signals and training a multi-layer perceptron model. Therefore, this work will realize the performance integration of functional hydrogel sensors as flexible wearable electronic devices, and provide innovative ideas for intelligent sensing in complex scenarios.

Developing a simple and efficient multi-functionally integrated absorber is promising but challenging. In this work, a lightweight but ultrahigh-strength polyvinyl alcohol (PVA)/aramid nanofiber (ANF)/carbon nanotube (CNT) (PAC) composite foam was fabricated through the self-assembly of hydrogen bonds. This composite foam had a hollow skeleton structure, achieving an ultra-high compressive strength of 6.71 MPa and could withstand a weight of more than 27,000 times its own weight. Its internal gradient pore structure provided a large number of reflection and scattering channels for the wastage of electromagnetic waves. Under the cooperation of impedance matching and multiple loss mechanisms, it exhibited a minimum reflection loss (RLmin) value of -59.12 dB and a wide effective absorption bandwidth (EAB) of 7.3 GHz. In addition, the PAC composite foam presented excellent radar and infrared stealth properties, and the radar cross-section scattering attenuation reached 42.92 dBm2, which showed great application advantages in complex environments. Therefore, such a convenient and efficient strategy is expected to provide a new route to design high-performance multifunctional integrated composite materials.

The working environment of the magnetorheological (MR) damper under high-speed impacts is harsh, the uncertainties in the models of each system component, unmodeled parts, as well as internal and external disturbances, can significantly affect the buffering performance. This paper suggests a model predictive control (MPC) method for the MR impact buffer system that incorporates the driver model to enhance the control performance of the system. The Buck driver circuit was first accurately modeled mathematically, and then the driver's hardware was fabricated. To confirm the effectiveness of the developed driver, experiments were conducted to test the driver's response time, ripple, and linearity of output current. The state equations of the system are obtained by linking the Buck circuit mathematical model with the magnetic induction response characteristics equation, and the prediction model of the system is produced through discretization. The impacts of temperature, hysteresis disturbance, and driver model on the system's control performance are examined using Simulink simulation. The results indicate that temperature, hysteresis disturbance, and driver model impacts increase the system's peak damping force by 466.8 N and 724 N, respectively. The MR impact buffer system contains the driver model's MPC simulation results, showing that the system's peak damping force is 4534.9 N, which represents a reduction of 32.5% and 17.7% compared to the open-loop control and the proportional-integral-derivative (PID) control, respectively, and the control effect demonstrates a significant "platform effect," confirming the superiority and efficacy of the proposed control approach.

As an important supplement to rigid robotic arms, the soft robotic arm demonstrates broader application potential in non-structural environments. This article proposes a modular soft robotic arm with a pneumatic network structure. Each module features three symmetrical and independent pneumatic cavities that can control air pressure to achieve axial elongation and spatial bending movements. Coordinated control of multiple modules enables enhanced motion capabilities. To analyze the motion and deformation of each module, we established a mathematical model describing the relationships between air pressure and bending/elongation deformation, using the constant curvature assumption and large deformation beam theory. Furthermore, we investigated the influence of the soft arm's gravity on deformation performance, providing modified analytical models for single-module and double-module configurations. The kinematic analysis was conducted to determine the soft arm's workspace through integration of the proposed model and kinematic model. Experimental validation showed bending and elongation angles agreeing well with theoretical predictions and finite element simulations under 0-80 kPa pressure, with maximum deviations below 5.7%. This work provides a theoretical foundation for optimizing the design and analysis of soft robotic arms.

The advancement of high-performance absorbers is essential for applications in electromagnetic wave absorption (EWA) and stealth technologies. To enhance EWA performances, it is imperative to employ advanced design strategies that incorporate heterogeneous interfaces and multi-scale structures. In this study, we developed a composite elastomer demonstrating exceptional EWA characteristics using a two-step process involving liquidphase reduction followed by thermal curing. High aspect ratio carbon nanotubes were integrated onto the surface of CoNi nanospheres, creating a multi-scale architecture with heterogeneous interfaces that ranged from zero-dimensional to two-dimensional. This innovative structural design significantly improved the EWA capabilities of the composite elastomer. Notably, even with only 15 wt% filler content, the composite elastomer achieved a minimum reflection loss of -54.4 dB at a thickness of 4 mm, alongside an adjustable effective absorption bandwidth exceeding 60 % of the 2-18 GHz frequency range. Additionally, it exhibited favorable mechanical strength and stretchability, enhancing its practical applicability. This work provides valuable insights into optimizing dielectric and magnetic properties through advanced structural design and underscores the

Anthropomorphic dexterous hands are crucial for robotic interaction in unstructured environments, yet their performance is often constrained by traditional actuation systems, which suffer from excessive weight, complexity, and limited compliance. Twisted String Actuators (TSAs) offer a promising alternative due to their high transmission ratio, lightweight design, and inherent compliance. However, their strong nonlinearity under variable loads poses significant challenges for high-precision control. This study presents an integrated approach combining data-driven modeling and biomimetic mechanism innovation to overcome these limitations. First, a data-driven modeling approach based on a dual hidden-layer Back Propagation Neural Network (BPNN) is proposed to predict TSA displacement under variable loads (0.1-4.2 kg) with high accuracy. Second, a lightweight, underactuated five-finger dexterous hand is developed, featuring a biomimetic three-phalanx structure and a tendon-spring transmission mechanism, achieving an ultra-lightweight design. Finally, a comprehensive experimental platform validates the system's performance, demonstrating precise bending angle prediction (via integrated BPNN-kinematic modeling), versatile gesture replication, and robust grasping capabilities (with a maximum fingertip force of 7.4 N). This work not only advances TSA modeling for variable-load applications but also provides a new paradigm for designing high-performance, lightweight dexterous hands in robotics.

Developing microwave-infrared compatible stealth porous foams is highly desirable for practical applications in areas of aerospace, military, and wearable electronics. Herein, a lightweight and dual-functional three-dimensional conductive network was constructed by assembling one-dimensional iron nanowires (FeNWs) on the porous melamine foam (MF) skeleton via one-step vacuum-assisted impregnation strategy. Benefiting from inherent porous structure, multi-scale heterogeneous interface, and strong magnetic-dielectric synergy, the as-developed MF@FeNWs composite foam exhibited superb electromagnetic wave absorption capacity with a minimum reflection loss of-36.5 dB and an effective absorption bandwidth of 2.4 GHz. Moreover, the composite foam possessed outstanding mechanical stability under the dynamic compressive cycles. More importantly, due to its low thermal conductivity of 0.0589 W/mK, the foam's surface saturation temperature remained nearly unchanged after persistent heating at 65 degrees C for over 1 h. Such remarkable results were largely attributed to the exceptional infrared stealth and thermal insulation characteristics. This study will provide new insights for rationally constructing the reliable composite foam materials to cater to the application requirements for various fields.

Two-dimensional MXenes have gained tremendous attention in the domain of electromagnetic wave absorption (EWA) owing to their outstanding conductivity and unique layered structures. Nevertheless, the disadvantages of easy stacking and non-magnetic properties often lead to incoordinate impedance matching and a single EWA mechanism, making it difficult to obtain optimal EWA performance. Herein, inspired by the hierarchically coral-like architecture, we demonstrated a controllable embedding strategy for in situ growing bimetallic CoNi metal-organic framework (MOF) derived carbon composite materials (CoNi@C) on the interlaminations of layered MXene via solvothermal and subsequent high-temperature annealing processes. The resultant MXene/CoNi@C showed excellent EWA capabilities, which mainly benefitted from a harmonious dielectric-magnetic coupling network with numerous heterointerfaces and porous structures brought about by interlaced CoNi nanorods. As anticipated, an optimal minimum reflection loss of -66.4 dB at 9.5 GHz, corresponding to an effective absorption bandwidth of 3.2 GHz, could be obtained by adjusting the ratios of MXene and CoNi-MOFs. This study will propose a bioinspired structure design strategy for developing high-performance MXene-based absorbers. High-performance MXene-based composites exhibit superior electromagnetic wave absorption capability, owing to the hierarchically coral-like architecture constructed by MXene and bimetallic CoNi-MOFs.

With the continuous development of the water transportation and shipping industries, the number of ships in rivers has steadily multiplied, followed by the increasing complexity of the ship routes. These changes have highlighted the growing importance of ship detection and water level measurement systems. Such systems not only enhance the management efficiency of waterborne traffic, ensure navigation safety, and reduce congestion and collision accidents, but also effectively safeguard the integrity of riverside and bridge structures. Ship detection and river elevation measurement based on 3D point clouds can directly acquire depth information without being affected by lighting conditions. So it has a good research prospect. Therefore, this paper proposes a novel ship detection algorithm based on improved PointRCNN and a novel method for riverbank line extraction and water level measurement based on 3D point clouds, respectively. For ship detection, the improved PointRCNN algorithm can increase the performance of data processing and keypoint extraction techniques, and make the network to keep more foreground point clouds and learn more effective features. This improves the recognition capability of distant ships. Compared to the original PointRCNN algorithm, the improved PointRCNN algorithm has achieved a 3.84% increase in detection precision in practical scenarios. Regarding riverbank extraction and water level measurement, the proposed method based on 3D point clouds can directly extract riverbank lines with depth information, obtaining water level height without direct contact with the river surface. Within a distance range between 15 and 45 m from the LiDAR, the average absolute error using this measurement method is less than 5 cm, demonstrating the good detection accuracy of this method.

Magnetorheological (MR) impact buffering systems are widely used in vehicle suspensions, bridge damping, and aircraft landing gear due to their excellent buffering performance and rapid response time. However, under the condition of high-speed continuous impact, magnetorheological damper (MRD) operate in complex environments where various internal and external uncertainties can negatively affect control performance. This paper analyzes the impact of disturbance signals on MR buffering systems and explores control strategies to mitigate these effects. First, we established a hysteresis model based on experimental data and identified parameters using a genetic algorithm to determine the influence of hysteresis disturbances. Next, we developed a temperature model based on the thermal characteristics of SG-MRF2035 magnetorheological fluid, fitting the relationship between temperature and dynamic viscosity to identify temperature disturbances. The results showed that when disturbances were considered, the system exhibited higher peak damping forces and a deviation from the desired 'platform effect' in the damping force-displacement relationship. Finally, we applied an Active Disturbance Rejection Control(ADRC) strategy, which effectively compensated for the hysteresis and temperature disturbances, enhancing the system's robustness. Compared to PID control, the ADRC-controlled system demonstrated lower peak damping forces and a damping force-displacement relationship closer to the desired platform effect.

Conductive hydrogels have received widespread attention in the field of flexible sensors. However, a single network structure inside the hydrogel sensor usually makes it difficult to bear larger mechanical loadings, greatly limiting practical applications. Developing a recoverable conductive hydrogel sensor with high toughness and adaptability is still challenging. Herein, a high-performance polyvinyl alcohol (PVA)-based conductive composite hydrogel was constructed, assisted by green cellulose nanofibrils (CNFs), magnesium chloride (MgCl2), ethylene glycol (EG), and liquid metal (LM). The synergistic effects between CNFs and LM enhanced the network structure inside the recoverable hydrogel. This resulted in an excellent tensile strength of 3.86 MPa with an elongation at break of as high as 918.4 % and compressive strength of 4.04 MPa at 80 % strain. In addition, the conductive network composed of MgCl2 and LM endowed the hydrogel good electrical conductivity. Moreover, it could be used as a flexible strain sensor for various application scenarios, e.g., micro-stress monitoring (water droplet falling) and information encryption transmission of Morse code. Such uniqueness will provide a design strategy for developing a new generation of hydrogel sensors.

Lightweight carbon-based aerogels with fast heat dissipation capability are promising electromagnetic wave absorber materials for developing integrated electronics, artificial intelligence, and human-interaction equip-ment under harsh thermal environments. Herein, the bimetallic (cobalt (Co) and nickel (Ni)) metal-organic frameworks (CoNi-MOFs), cellulose nanofibrils (CNFs), and aramid nanofibers (ANFs) were assembled into a conductive and magnetic CoNi@carbon/ANF/CNF carbon composite aerogel (CoNi@C/ACA) with an ultra-low density of 6.15 mg/cm3 using freeze-drying and subsequent carbonization treatment. Owing to the synergistic effects of multiple reflections inside the three-dimensional interconnected structures, abundant interfacial/ dipolar polarizations, and coordinated dielectric and magnetic losses, the CoNi@C/ACA achieved a fascinating minimum reflection loss value of-66.57 dB and broad effective absorption bandwidth up to 6.3 GHz, which were characterized with an ultra-low loading of 1.8 wt%. In addition, it displayed good thermal stability with a super-fast Joule heating (cooling) rate at low driving voltages. These unique characteristics of the ultra-light CoNi@C/ACA make it a promising material for demanding applications, e.g., electromagnetic pollution elimi-nation and thermal management.

Wearable flexible sensors based on conductive hydrogels have received extensive attention in the fields of electronic skin and smart monitoring. However, conductive hydrogels contain a large amount of water, which greatly affects their performances in harsh environments. It is therefore necessary to prepare hydrogel sensors that are stable at low temperatures. Herein, metal ions (MgCl2) and ethylene glycol (EG) were combined with polyvinyl alcohol (PVA) to obtain a conductive PVA/EG hydrogel with tensile strength and elongation at break of 1.1 MPa and 442.3 %, respectively, which could withstand >6000-fold its own weight. The binary solvent system composed of water and EG contributed to the excellent anti-freezing properties and long-term storage (>1 week), flexibility, and stability of the hydrogel even at-20 degrees C. The wearable PVA/EG hydrogel as a flexible sensor possessed desirable sensing performances with a competitive GF value of 0.725 and fatigue resistance (50 cycles) when used to monitor various human motions and physiological signals. Overall, this hydrogel sensor shows strong potential for application in the fields of human motion monitoring, written information sensing, and information encryption and transmission.

Two-dimensional (2D) MXene has attracted vast attention in electromagnetic wave absorption (EWA), but there remains a contradiction between maintaining impedance matching and enhancing dielectric loss. Herein, the multi-scale architectures of ecoflex/2D MXene (Ti3C2Tx)@zero-dimensional CoNi sphere@one-dimensional carbon nanotube composite elastomers were successfully constructed by simple liquid-phase reduction and thermo-curing method. The binding between the hybrids as fillers and ecoflex as a matrix greatly enhanced the EWA capability of the obtained composite elastomer and improved its mechanical properties. Owing to its good impedance matching, abundant heterostructures, and synergistic electrical and magnetic losses, this elastomer exhibited an excellent minimum reflection loss of -67 dB at 9.46 GHz under a thickness of 2.98 mm. In addition, its ultrabroad effective absorption bandwidth reached 6.07 GHz. This achievement will pave the way for the exploitation of multi-dimensional heterostructures as high-performance electromagnetic absorbers with superior EWA ability.

Currently, electromagnetic interference (EMI) shielding and microwave absorption are two important means to alleviate the increasingly severe electromagnetic (EM) pollution. However, the application areas of EMI shielding and microwave absorption are quite different, so integrating these two capabilities in the same material is a great challenge. Herein, multiple-scale polyurethane (PU) composite foams (CFs) assisted by tadpole-like carbon nanotube (CNT)@Fe3O4 nanocomposites were designed by a facile solvothermal and self-foaming method. By adjusting the CNT@Fe3O4 loadings and ambient temperatures, the EM parameters and interface impedance matching of PU/CNT@Fe3O4 CFs could be optimized, thus realizing the coexistence of EMI shielding and microwave absorption inside one same material. The resulting CF exhibited an effective minimum reflection loss (RLmin) of -41.9 dB and EMI shielding effectiveness (SE) of similar to 20 dB. Furthermore, the elevated temperatures within a range of -20-60 degrees C would stimulate the transformation of individual CF from microwave absorption towards EMI shielding capability and vice versa. This work will promote the development of intelligent EM compatible devices in the field of optional EM protection.

螺栓是一种临时连接件,螺栓连接是目前木结构的主要连接方式,广泛应用于建筑、运输等领域.木结构螺栓连接产生松动问题的原因主要有冲击力、应力集中、裂纹、腐蚀等,冲击力容易导致木结构螺栓连接松动问题.设计了一种基于压电时间反演法的木材连接螺栓松动检测系统.利用NI-ELVISⅡ+数据采集卡并设计LabVIEW程序,发生Lamb波冲击信号.利用粘贴在木板上的两片压电陶瓷分别产生振动,对发射的超声波信号进行两次测量,其中第一次测量的信号经时间反演后作为二次超声波信号的发生.由于冲击信号持续的时间很短,约10 ms,因此检测系统设计了二次数字触发以确保信号的完整记录.应用设计的检测系统测试了几组不同螺栓预紧力作用下的超声波信号,结果表明聚焦信号的幅值随着螺栓预紧力的增大而增大.因此,该检测系统可通过测试聚焦信号的幅值反映螺栓的松动状态,通过观察聚焦信号的幅值可以分析预紧力的大小,确保轴向力施加适当,系统同时具有精度高、响应迅速等优点.

Protecting the occupants from surviving the casualties and severe injuries in elevator emergency crashes is always essential. This paper aims to explore the feasibility of using multiple magnetorheological shock absorbers (M-MRSAs) to attain the soft landing of a full-load elevator under impact velocities ranging up to 32 m/s. The resistance forces of MRSA with a bi-fold structure are predicted by evaluating the pressure drops using a nonlinear Bingham-plastic model considering the effects of minor loss. The optimal control for an M-MRSAs system achieving robustness concerning different mass loadings and impact velocities is investigated by formulating a multi-objective problem to minimize the induced peak acceleration with constrained time duration. The results demonstrate that the self-adapting MR yield force provides a smooth operation by minimizing the cycles of re-crash and rebound without incurring an end-stop impact. Furthermore, a plateau behavior of acceleration-displacement profiles is realized to effectively reduce the load transmission from overshoot accelerating force to the protected occupants and eliminate the injury risk.

液态金属是一种新型功能材料,具有不定型、可流动性,在室温下可呈液态.镓基液态金属(GLM)是其中一种安全无毒的液态金属,具有良好的流动性、导热性、热稳定性、导电性等,因其优异性能已被应用于多种领域.目前,国内研究镓基液态金属作为润滑剂的研究还处于起步状态.介绍了影响镓基液态金属润滑性能的外界因素,并提出了镓基液态金属作为润滑剂的几个需要解决的问题.

In the magnetorheological (MR) impact buffer system, the internal or external disturbance of the MR damper is one of the main factors that affect the buffer performance of the system. This study aims to suppress or eliminate the influence of the disturbance of the MR damper. The continuous terminal sliding mode control (CTSMC) strategy with a high gain has a strong antidisturbance ability. However, the high gain may cause fluctuation of the damping force of the system. Therefore, a composite control strategy of sliding mode active disturbance rejection control (ADRC) based on an extended state observer (ESO) is proposed in this study. The total disturbance of the system is estimated by the ESO in real time, and the estimated disturbance is used as a feedforward compensation to the controller to reduce the influence of disturbance on the system. The gain of the CTSMC law of the closed-loop system can be reduced. In addition, the Lyapunov stability criterion is used to ensure the stability of the proposed controller. In order to verify the performance of the proposed CTSMC controller on response speed, overshoot, and hysteresis suppression ability, the window function, square wave function, and multistep function are given as the inputs of the control system. To verify the performance of the proposed sliding mode ADRC for the MR impact buffer system, the mechanical model and the control model are established and simulated using MATLAB/Simulink. The simulation results show that the CTSMC controller has the fastest response time and no overshoot and can suppress the hysteresis nonlinearity of the MR device compared with the open-loop control, PID control, and fractional order PID control. The MR impact buffer system with the sliding mode ADRC obtained the minimum peak value of 4350N within the permitted buffer displacement range compared with the other three traditional control methods. That means the proposed control method in this study has the advantage on buffer performance for the MR impact buffer system.