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One-Step Sol-Gel Facile Synthesis and 3D Nanoscale Morphology Investigation of Bi0.5Na0.5TiO3-BaTiO3 Thin Films
Full text linkAbstract: Bismuth sodium titanate, denoted as Bi0.5Na0.5TiO3-BaTiO3 (BNT-BT), possessing a perovskite-like structure, has emerged as a highly prospective material in recent years. It is considered a prime contender for replacing PZT-based compounds due to its exceptional piezoelectric and ferroelectric properties, coupled with the presence of loosely bound pairs of chemically active electrons. This study delves into the micromorphological properties of BNT-BT thin film electrodes, fabricated using sol-gel spin-coating and subsequent annealing processes. Employing Atomic Force Microscopy (AFM), comprehensive 2D and 3D topographical maps were acquired, enabling the extraction of pivotal parameters crucial for surface characterization. Notably, the investigation encompasses Minkowski Functionals, which encompass normalized Minkowski volume, boundary, and connectivity analyses. In conjunction, various roughness parameters, encompassing arithmetic mean height, maximum peak height, maximum valley depth, arithmetic mean depth, and the ten-point height parameter, were quantified across these analyses to facilitate a comprehensive comparison of surface morphologies among distinct samples. The morphological analysis outcome underscores the potential for elucidating material performance through microstructural shape and quantitative roughness evaluation of respective surfaces. This holds significant promise for applications such as predictive assessment of functional behavior, including industrial quality control during sample manufacturing processes
Evaluation of Thermal and Mechanical Properties of Epoxy Resin/Aluminum Nanoparticle Composites
Full text linkAbstract: In this study, we explored the development of epoxy resin nanocomposites with 0.1, 0.3%, and 1.0% by weight of aluminum nanoparticles. These nanocomposites were evaluated for mechanical properties (tensile test and Izod strength test) and thermal properties (differential scanning calorimetry and thermogravimetric analyses), and their morphology was assessed using field emission gun scanning electron microscopy. Adding even small amounts of aluminum nanoparticles led to notable improvements in the mechanical and thermal resistance. Remarkably, composites with 1.0 wt% of aluminum nanoparticles presented a 25% increase in the elastic modulus, a 20 °C increase in the glass transition temperature, and a 30 °C increase in the degradation temperature. These findings hold significant promise for advancing the field of polymer-metal nanocomposites
Research on Occupant Safety in Frontal Collision Based on Different Sitting Positions of Intelligent Vehicles
Full text linkAbstract: To study the safety of drivers with different sitting positions in intelligent vehicle collision, the slide model of SUV was established and the precision of the model was verified by slide test. The simulation model of driver\u27s attitude was established by THUMS. According to the results of post mortem human surrogate (PMHS), the sitting postures of THUMS at different seat backrest angles were adjusted and the drivers’ injuries of three sitting postures in frontal collision were analyzed. Simulation results show that when the driver was in semi-recumbent and reclining posture, the protective effect of the airbag on the head was obviously reduced in collisions, and the head and chest will be seriously damaged due to the large seat backrest angle, resulting in increased distance between the head and the wheel. Besides, the tilting sitting posture leads to the risk of sunken seat in the collision. Therefore, with the development of autonomous driving technology, not only should intelligent vehicles meet occupants’ comfort requirements, but the collision safety caused by the change of sitting postures should be considered
Design and Simulation Analysis of Robot-Assisted Plate Internal Fixation Device for Lower Limb Fractures
Full text linkAbstract: Internal fixation with steel plates is a common method for the therapy of lower limb fractures. Due to the disadvantages of traditional surgical methods such as high trauma and complications, the application of robots for minimally invasive surgery has become a popular research direction. In this article, we have designed and simulated the overall structure of a steel plate internal fixation device used in conjunction with a robotic arm. Firstly, a finite element model of cortical bone drilling was established based on ABAQUS to obtain the torque and axial force when drilling the cortical bone. Then a virtual prototype of the robot-assisted lower limb bone fracture plate internal fixation device was designed, and the outer shell, drilling mechanism, nail placement mechanism, nail supply mechanism, drive mechanism, and guide sleeve were refined based on the overall mechanical structure of the device, so that the device could continuously perform drilling and nail placement. Afterward, the device was simulated based on ADAMS, and the motion curves of each component were obtained to verify the feasibility of the device’s working principle and to validate the performance of the servo. Finally, the modal analysis of the device was carried out with the finite element software ABAQUS, and the modal parameters of the first six orders were obtained, which were compared with the operating frequencies of the motor and the servo to verify that the device is not easy to resonate during normal operation, and the static strength checks of the key components were carried out, and the stress and deformation clouds and upper limits of flexural values of the components were obtained, which proved that the structure has stability
Data–Driven Wake Steering Control for a Simulated Wind Farm Model
Full text linkAbstract: Upstream wind turbines yaw to divert their wakes away from downstream turbines, increasing the power produced. Nevertheless, the majority of wake steering techniques rely on offline lookup tables that translate a set of parameters, including wind speed and direction, to yaw angles for each turbine in a farm. These charts assume that every turbine is working well, however they may not be very accurate if one or more turbines are not producing their rated power due to low wind speed, malfunctions, scheduled maintenance, or emergency maintenance. This study provides an intelligent wake steering technique that, when calculating yaw angles, responds to the actual operating conditions of the turbine. A neural network is trained live to determine yaw angles from operating conditions, including turbine status, using a hybrid model and a learning-based method, i.e. an active control. The proposed control solution does not need to solve optimization problems for each combination of the turbines’ non-optimal working conditions in a farm; instead, the integration of learning strategy in the control design enables the creation of an active control scheme, in contrast to purely model-based approaches that use lookup tables provided by the wind turbine manufacturer or generated offline. The suggested methodology does not necessitate a substantial amount of training samples, unlike purely learning-based approaches like model-free reinforcement learning. In actuality, by taking use of the model during back propagation, the suggested approach learns more from each sample. Based on the flow redirection and induction in the steady state code, results are reported for both normal (nominal) wake steering with all turbines operating as well as defective conditions. It is a free tool for optimizing wind farms that The National Renewable Energy Laboratory (USA) offers. These yaw angles are contrasted and checked with those discovered through the resolution of an optimization issue. Active wake steering is made possible by the suggested solution, which employs a hybrid model and learning-based methodology, through sample efficient training and quick online evaluation. Finally, a hardware-in-the-loop test-bed is taken into consideration for assessing and confirming the performance of the suggested solutions in a more practical setting
Circular Economy: A Network Analysis of the Solid Waste Collection in the City of Rome (Italy)
Full text linkSolid waste management represents a complex issue involving political, socioeconomic, institutional, urbanistic and environmental aspects. Separate collection of waste in the Municipality of Rome is a matter of particular interest due to the size of the city (with an urban area of 1,287 km²) and the considerable amount of waste produced (approximately 1,690,000 tons/year). In this context, this paper proposes an in-depth analysis with the aim of optimizing the delivery of waste to collection centres. The optimization focuses on several key elements, including the strategic distribution of collection centres within the city to make them easily accessible, particularly in densely populated areas or where waste production is higher.
Based on the data provided by the Municipality of Rome, the waste materials that should be advantageously recycled as part of the Life Cycle Assessment (LCA) have also been identified. This comprehensive approach can improve the city’s waste management system, promoting the efficient use of resources and reducing environmental impact for greater urban sustainability
Bacterial Cellulose: A Multifunctional Platform for Biomedical Applications
Full text linkBacterial cellulose (BC), a biopolymer synthesized by various bacterial species, has emerged as a promising material for biomedical applications due to its unique properties, including high purity, biocompatibility, mechanical strength, and structural similarity to the extracellular matrix. This review explores the advancements in BC research over the last decade, focusing on its applications in tissue engineering, wound healing, and drug delivery systems. While BC offers numerous benefits, challenges such as large-scale production, structural modification, however regulatory approval hinder its broader clinical use. Recent studies have introduced innovative solutions, such as using agro-industrial waste to lower production costs and combining BC with other materials to enhance its bioactivity. As research progresses, BC has the potential to revolutionize the field of biomedicine, offering sustainable, versatile, and effective solutions for a wide range of medical applications
Self-Organized Multi-Robot Path Planning and Chain Distribution Based on Improved DWA and A* Fusion in Unknown Space
Full text linkWith the rise of autonomous driving in recent years, path planning has gained widespread attention. Traditional path planning needs to be based on a large amount of known information, which is not available for confined environments. Taking the complex indoor space where GPS cannot be used as the research background, the article designs a self-organised motion scheme for multi-intelligent body trolleys that includes exploration and path planning. By improving the DWA and A* algorithms, the multi-robot self-organisation achieves reasonable path planning, and the fusion of the two algorithms solves the contradictory problems of global planning being unable to avoid dynamic obstacles and local planning possibly falling into local optimum. After that, the pilot-following algorithm is added to guide the multi-intelligence body to operate in formation. By studying the constraints of hardware such as LiDAR and machine trolleys, the chain distribution of multiple intelligences is proposed to solve the problem of information loss caused by the discontinuous monitoring field of view. Eventually, when the carts are all in position, the whole area is covered and monitored using sensor fusion with multiple viewpoints. The feasibility of the explored scheme is verified by simulation experiments, and the feasibility and robustness of multi-sensor fusion is verified by specific hardware
Triboresistance of Composite Nanocoatings Based on Magnesium Compounds at Elevated Temperatures
Full text linkThe results of the study of the wear characteristics of detonation composite nanocoatings based on magnesium orthosilicate under conditions of high-temperature friction under constant load in the field of sliding speeds, on the surface of which stable antifriction structures are formed under conditions of elevated temperatures, are presented. The structural-phase composition of the coatings was determined by methods of modern physical analysis and the complex of high-temperature compounds of the surface layers was determined. The developed and studied coatings have high and stable antifriction properties. It was determined that the antifriction property under friction loading is due to the self-ordering of surface high-temperature oxide and oxygen-free structures, which are characterized by low shear resistance and work as solid lubricants that modify the contact surfaces and prevent damage to moving joints
Signal Injection Test of Spoofing Attack to GNSS-Based Positioning in Railway Train Control
Full text linkWith the continuous development of the railway transportation system, train operation control is becoming more and more significant as the core to guarantee the operational safety and efficiency. Train control based on Global Navigation Satellite System (GNSS) is an important way to improve on-board sub-system autonomy and reduce the dependence on trackside facilities. However, the vulnerability of GNSS makes GNSS-based train positioning susceptible to the spoofing attack, which affects its ability to be used for novel train control systems. For this reason, it is of great significance to conduct specific test and evaluation for train positioning research, development, and applications. In this study, we construct an overall framework of spoofing injection test for GNSS-based positioning in train control, and analyze the detailed contents of test and evaluation, including spoofing attack configuration, test scenario design and generation, test dataset establishment and analysis, and typical evaluation metrics. In order to fully demonstrate the effectiveness of the proposed framework, a complete spoofing injection test environment is established. Through case studies concerning two typical spoofing modes, we successfully illustrate the effectiveness of the proposed scheme in testing and evaluating the spoofing tolerant capability and performance features of GNSS receivers dedicated to train positioning. Finally, we discuss the direction of subsequent trusted applications of GNSS in train control systems using the presented solution and platform. The results provide relevant ideas for the research of novel GNSS spoofing protection techniques for future intelligent railway systems