Steerable catheters offer significant advantages over conventional catheters, including enhanced control, stability, and accessibility, which reduce operational complexity, fluoroscopy time, and radiation exposure, positioning them as a promising advancement for vascular interventional procedures. Herein, a novel steerable catheter is presented, featuring a hydraulically actuated, soft, steerable tip that allows for real‐time visualization in X‐ray imaging. To optimize performance, several silicone materials were evaluated for their mechanical properties, resulting in a soft tip design with a diameter of 2.6 mm. The tip incorporates an internal tool channel and supports a large bending angle of 180°. The tip demonstrates an average response time of 1.141 s (±0.750 s), a maximum output force of 0.145 N (±0.001 N), and a maximum radial expansion of 1.121 (±0.006). A steering kinematic model of the catheter tip is developed to simulate its movement. The catheter tip's real‐time shape and position information are obtained through intelligent segmentation and neighborhood‐based endpoint detection methods, assisting the surgeon during superselective procedures. The catheter's visibility and flexibility are validated in a live porcine model, demonstrating its potential for future use in interventional procedures.
Computer engineering. Computer hardware, Control engineering systems. Automatic machinery (General)
In the manufacturing of iron core for high-power transformers, a cutting stock problem arises where large-width silicon steel coils must be cut into narrower coils, known as strips. Typically, the required length of each strip far exceeds that of a single coil. Therefore, the problem necessitates additional consideration of how to split the strips and arrange them on the large coils, with the goal of minimizing the total number of strips. In this paper, we propose a discrete artificial bee colony algorithm to address this problem. The algorithm replaces the stochastic roulette wheel with biased selection in the onlooker bee phase and introduces partially mapped crossover in both the onlooker and scout bee phases. These enhancements facilitate more effective utilization of information from high-quality solutions, thereby improving the algorithm’s stability and its capacity to obtain higher-quality results. Experimental results show that compared to existing methods reported in the literature, the proposed approach reduces the total number of strips by an average of over 3.9% and 7.6% for Set 2 and Set 3, respectively, while also exhibiting a faster convergence rate than other competitive algorithms.
As a critical component in fuel cell air supply systems, air compressors account for approximately 20 % of the total power consumption in fuel cell systems, significantly limiting overall efficiency improvement. This study proposes a novel enhanced interstage air-cooling method for two-stage centrifugal supercharging systems applied in fuel cells. Two compact interstage air-cooling configurations were designed, and corresponding full-domain Computational Fluid Dynamics (CFD) simulation models of the two-stage supercharging system were established to analyze the aerodynamic performance enhancement through interstage air-cooling. The research results show: (1) The interstage air-cooling expands the surge margin of the two-stage supercharging system, and broadens the high-efficiency operating range (isentropic efficiency ≥70 %) by 77.8 % and 74.6 % respectively. (2) At design conditions, the two interstage air-cooling schemes respectively reduce the average temperature at the high-pressure stage outlet section by 6.1 K and 8.0 K, correspondingly decrease system power consumption by 2.04 % and 2.25 %, and improve efficiency by 1.64 % and 1.61 % respectively; (3) Under near-surge operating conditions, the two-stage centrifugal pressurization system exhibits performance improvement. This study provides theoretical analysis basis for performance optimization of two-stage centrifugal pressurization systems and offers reference for product design.
Exoskeletons that make running easier could increase users’ physical activity levels and provide related health benefits. In this paper, we present the design of a portable, powered ankle exoskeleton that assists running and uses lightweight and compact twisted string actuators. It has limited durability at this stage of development, but preliminary results of its power to mass density and potential for reducing the metabolic cost of running are promising. The exoskeleton can provide high peak power of 700 W per leg, 7 times more than prior twisted-string devices, and high peak torques of 43 Nm. Kinetostatic and dynamic models were used to select mass-optimal components, producing a device that weighs 1.8 kg per leg and 2.0 kg in a backpack. We performed preliminary tests on a single participant to evaluate the exoskeleton performance during both treadmill running and outdoor running. The exoskeleton reduced metabolic energy use by 10.8% during treadmill running tests and reduced cost of transport by 7.7% during outdoor running tests compared to running without the device. Unfortunately, the twisted string wore out quickly, lasting an average of 4 min 50 s before breaking. This exoskeleton shows promise for making running easier if string life challenges can be addressed.
Observing the intricate microstructure changes in abrasive flow machining with traditional experimental methods is difficult. Molecular dynamics simulations are used to look at the process of abrasive flow processing from a microscopic scale in this work. A molecular dynamics model for micro-cutting a single crystal γ-TiAl alloy with a rough surface in a fluid medium environment is constructed, which is more realistic. The evolution of material removal, cutting force, temperature, energy, and dislocation during micro-cutting are analyzed. The impact of cutting depth, abrasive particle sizes, and abrasive material on the micro-cutting process are analyzed. The analysis shows that the smaller cutting depth and abrasive particle sizes are beneficial to obtain a better machining surface, and the cubic boron nitride (CBN) abrasive is an effective substitute material for diamonds. The purpose of this study is to provide unique insights for improving the material removal rate and subsurface quality by adjusting machining parameters in actual abrasive flow precision machining.
The increasing adoption of electric vehicles (EVs) has driven extensive research and development efforts to optimize the performance and safety of their energy-storage systems, particularly lithium-ion battery packs (LIBPs). Elevated temperatures in EV batteries primarily result from thermal instability during various operating, traveling, and charging conditions. In formula student electric vehicle (FSEV) competitions, where efficiency and reliability are critical, effective cooling of the battery pack (BP) is essential. This study analyzed the cooling performance of an air-cooled thermal management system using relevant system parameters and precise thermal modeling through CFD simulations. Various cooling parameters, such as coolant flow rate, fan speed, and cooling channel geometry, were systematically adjusted to evaluate their effects on BP temperature distribution, thermal equilibrium, and overall performance. Key metrics, including maximum temperature and temperature distribution within the battery module, were used to compare simulation results and optimize outcomes for future applications. Experiments validated the simulations of the optimal solution. The results of this investigation provide valuable insights for designing and improving active cooling systems for LIBPs in FSEVs. The average variance of the obtained temperature data was 4.256% based on simulation results. At an air velocity of 17 m·s−1, the BP temperature remained within the ideal range of 30–40 °C. Enhanced cooling strategies can improve the thermal stability of BPs, extend their lifespan, and reduce the risk of thermal runaway.
A conductive composite is a conductive material composed of conductive fillers in a nonconductive matrix. Among them, stretchable conductive composites (SCCs) generally consist of conductive fillers dispersed in elastomer and thus have a much higher mechanical stretchability than rigid metal or carbon conductive materials. Due to the ability to preserve electrical conductivity under mechanical deformation, SCCs have shown attractive applications in stretchable devices such as soft robots and wearable electronics. Most SCCs are filled with only one type of conductive filler and are thus called single-filler composites. Single-filler SCCs inevitably suffer from limitations such as low mechanical strength, poor stretchability, uneven filler dispersion, insufficient conductivity, degradation caused by oxidation, and poor repeatability. To solve these problems, many recent studies have introduced secondary fillers to enhance the physical or chemical properties of composites. These composites filled with multiple fillers are called hybrid-filler composites. There are a variety of reasons as to why secondary fillers are attractive. Their main function in hybrid-filler SCCs is to enhance the electrical conductivity by dispersing or bridging the primary fillers or by producing a synergistic effect with them. For instance, filler aggregation is a major problem for conductive composites filled with carbon fillers such as carbon nanotubes (CNTs), graphene, and carbon black (CB), which not only ineffectively uses the filler but also reduces the mechanical strength and electrical conductivity of the composites. There are two main ways to solve this problem by introducing secondary fillers. One method is to use conductive polymers (CPs) (e.g., polyaniline) or dispersants (e.g., polyvinylcarbazole-based compatibilizer, β-cyclodextrin, and silane) as secondary fillers to improve the interface interaction between the carbon fillers and the matrix, thereby more uniformly dispersing them in the matrix. Another method is to add secondary conductive fillers like metal nanoparticles (NPs) or other carbon fillers with different geometric shapes to achieve dispersion by breaking up filler aggregates during mixing. The homogeneous dispersion of the main fillers can generally reduce its percolation threshold and enhance the electrical conductivity and mechanical strength of the composite. In addition, conductive secondary fillers can also fill Dr. G. Yun, H. Lu, Prof. W. Li School of Mechanical, Materials, Mechatronic and Biomedical Engineering University of Wollongong Wollongong, NSW 2522, Australia E-mail: weihuali@uow.edu.au Dr. S.-Y. Tang Department of Electronic, Electrical and Systems Engineering University of Birmingham Edgbaston, Birmingham B15 2TT, UK E-mail: S.Tang@bham.ac.UK Prof. S. Zhang Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes Department of Precision Machinery and Instrumentation University of Science and Technology of China Hefei, Anhui 230027, China Prof. M. D. Dickey Department of Chemical and Biomolecular Engineering North Carolina State University Raleigh, NC 27695, USA E-mail: mddickey@ncsu.edu
L. Penolazzi, Anna Chierici, Maria Pina Notarangelo
et al.
The degeneration of intervertebral disc (IVD) is a disease of the entire joint between two vertebrae in the spine caused by loss of extracellular matrix (ECM) integrity, to date with no cure. The various regenerative approaches proposed so far have led to very limited successes. An emerging opportunity arises from the use of decellularized ECM as a scaffolding material that, directly or in combination with other materials, has greatly facilitated the advancement of tissue engineering. Here we focused on the decellularized matrix obtained from human umbilical cord Wharton's jelly (DWJ) which retains several structural and bioactive molecules very similar to those of the IVD ECM. However, being a viscous gel, DWJ has limited ability to retain ordered structural features when considered as architecture scaffold. To overcome this limitation, we produced DWJ-based multifunctional hydrogels, in the form of 3D millicylinders containing different percentages of alginate, a seaweed-derived polysaccharide, and gelatin, denatured collagen, which may impart mechanical integrity to the biologically active DWJ. The developed protocol, based on a freezing step, leads to the consolidation of the entire polymeric dispersion mixture, followed by an ionic gelation step and a freeze-drying process. Finally, a porous, stable, easily storable, and suitable matrix for ex vivo experiments was obtained. The properties of the millicylinders (Wharton's jelly millicylinders [WJMs]) were then tested in culture of degenerated IVD cells isolated from disc tissues of patients undergoing surgical discectomy. We found that WJMs with the highest percentage of DWJ were effective in supporting cell migration, restoration of the IVD phenotype (increased expression of Collagen type 2, aggrecan, Sox9 and FOXO3a), anti-inflammatory action, and stem cell activity of resident progenitor/notochordal cells (increased number of CD24 positive cells). We are confident that the DWJ-based formulations proposed here can provide adequate stimuli to the cells present in the degenerated IVD to restart the anabolic machinery.
AbstractA balancing control algorithm for a wheel-legged robot is designed for current logistics and distribution mobile robots. Since the wheel-legged robot is a nonlinear underactuated system, it is crucial to realize the balanced control and robustness of the wheel-legged robot in the absence of an accurate dynamics model. In this paper, an optimal control scheme for the wheel-legged robot based on the fusion control of variable-height adaptive fuzzy PID and conventional PID is designed. The balance of the wheel-legged robot is controlled by adaptive fuzzy PID control, the lifting and attitude changes of the two sides of the wheel-legs are controlled with high precision by traditional PID control, and the speed and steering control of the wheel-legged robot is not affected by the structure of the model, and is controlled by traditional PID control with linearization. The attitude of the robot is detected in real time using the BMI088 attitude sensor to realize the positional control. Experimental and simulation results show that the control algorithm of the wheel-legged robot designed in this paper is reliable, and the robot runs smoothly and robustly.
AbstractComprehensive exploration of ball-end milling processes is presented in this paper, with a primary focus on the modelling of milling forces and the execution of finite element analysis during the machining of Inconel 718, a material known for its challenging machinability. A detailed milling force model, considering various parameters such as cutting speeds, feed rates, and depths of cut, has been developed, providing valuable insights into the optimization of machining parameters. Temperature and stress distributions within the tool during milling, particularly in the context of difficult-to-machine materials like Inconel 718, were investigated through finite element analysis. Critical temperature profiles at the tool tip, rake face, and flank face, which have an impact on tool wear and lifespan, were identified through the temperature field analysis. Notably, a maximum tool tip temperature of 682 °C was observed during the machining of Inconel 718. Challenges posed by difficult materials were unveiled through the stress field analysis, aiding in stress mitigation and enhancing the understanding of machining processes. In conclusion, a significant contribution is made by this paper to the understanding of ball-end milling processes.
AbstractIn response to the low design efficiency caused by the numerous design parameters of existing shock absorbers, this research presents the design of an efficient software tool for obtaining the external characteristics of Continuous Damping Control (CDC) shock absorbers. Firstly, a mathematical model for the damping force of the shock absorber was established based on principles from fluid dynamics, elasticity mechanics, and throttle orifice models in the rebound and compression valve systems. Secondly, a Graphical User Interface (GUI) was developed to visualize the external characteristics and conduct simulation studies of the CDC shock absorber. Finally, experiments were performed on a shock absorber test bench to validate the external characteristics of the CDC shock absorber using initial structural parameters. The GUI software interface enables direct adjustment of the shock absorber's structural parameters and signal excitation, thereby enhancing the practical efficiency of the shock absorber. A comparison between simulation and experimental results reveals that the relative error rate is generally high when the velocity amplitude is 0.052m/s, with a maximum relative error rate of 24.44%. For other excitation velocity amplitudes, the relative error rate remains within 10%. This demonstrates the high accuracy and reliability of the established mathematical model for the CDC shock absorber, providing a solid theoretical foundation for studying the shock absorber's external characteristics.
In this paper, an innovative method for energy recovery and management of the electronically controlled suspension system is proposed and simulated using MATLAB/Simulink, with the aim of enhancing energy efficiency and environmental sustainability. This method employs an integrated control approach based on force-position for tillage depth control. When the tractor suspension is positioned above the soil surface and descending, the PMSM switches to generator mode and uses the PMSM for energy recovery. The simulation results demonstrate the viability of energy recovery in heavy agricultural machinery, offering novel ideas and techniques for effective energy management in such equipment.
AbstractIn recent years, the new energy vehicle industry has been vigorously developed, and the demand for new energy vehicle practitioners and their knowledge of electric vehicles has been continuously increasing. In the undergraduate education of vehicle engineering, there is an urgent need for an electric drive demonstration teaching platform. This design aims to solve the teaching demonstration function of multiple configurations of electric vehicle drive systems on the same platform. The electric vehicle drive demonstration teaching platform is designed as an expandable way, which can meet the requirements of various combinations of different motor forms, battery types and capacities, control methods, etc. for platform loading and demonstration, achieving diversification of the teaching platform. It can also conduct experiments on various types of new energy vehicle configurations through connecting racks The expansion of the demonstration teaching platform meets the needs of teaching demonstrations and experiments related to electric vehicle drive systems.