Search Results (258)

The growing popularity of Personal Light Electric Vehicles (PLEVs), such as e-scooters, has revolutionized urban mobility by offering compact, cost-effective, and environmentally friendly transportation solutions. However, safety concerns, including inadequate infrastructure, poor protective measures, and high accident rates, remain critical challenges. This paper presents the design and development of an innovative self-balancing microvehicle under the H2020 LEONARDO project, which aims to address these challenges through advanced engineering and user-centric design. The vehicle combines features of monowheels and e-scooters, integrating cutting-edge technologies to enhance safety, stability, and usability. The design adheres to European regulations, including Germany’s eKFV standards, and incorporates user preferences identified through representative online surveys of 1500 PLEV users. These preferences include improved handling on uneven surfaces, enhanced signaling capabilities, and reduced instability during maneuvers. The prototype features a lightweight composite structure reinforced with carbon fibers, a high-torque motorized front wheel, and multiple speed modes tailored to different conditions, such as travel in pedestrian areas, use by novice riders, and advanced users. Braking tests demonstrate deceleration values of up to 3.5 m/s², comparable to PLEV market standards and exceeding regulatory minimums, while smooth acceleration ramps ensure rider stability and safety. Additional features, such as identification plates and weight-dependent motor control, enhance compliance with local traffic rules and prevent misuse. The vehicle’s design also addresses common safety concerns, such as curb navigation and signaling, by incorporating large-diameter wheels, increased ground clearance, and electrically operated direction indicators. Future upgrades include the addition of a second rear wheel for enhanced stability, skateboard-like rear axle modifications for improved maneuverability, and hybrid supercapacitors to minimize fire risks and extend battery life. With its focus on safety, regulatory compliance, and rider-friendly innovations, this microvehicle represents a significant advancement in promoting safe and sustainable urban mobility. Full article

The current study examines the influence of a varying gravity field and its interaction with density stratification. This represents a novel area in baroclinic flow analysis. The classical vortex and internal wave structures in stratified flows are shown to be significantly modified when gravity varies with height. Vortices may shift, stretch, or weaken depending on the direction and strength of gravity variation, and internal waves develop asymmetries or damping that are not present under constant gravity. We examine the influence of gravity variation on the flow of both homogeneous and density-stratified fluids in a channel with topography consisting of a Gaussian obstacle lying at the bottom of the channel. The flow is without inertia, induced by the translation of the top plate. Both the density and gravity are assumed to vary linearly with height, with the minimum density at the moving top plate. The narrow-gap approach is used to generate the flow field in terms of the pressure gradient along the top plate, which, in turn, is obtained in terms of the bottom topography and the three parameters of the problem, namely, the Froude number and the density and gravity gradients. The resulting stream function is a fifth-order polynomial in the vertical coordinate. In the absence of stratification, the flow is smooth, affected rather slightly by the variable topography, with an essentially linear drop in the pressure induced by the contraction. For a weak stratified fluid, the streamlines become distorted in the form of standing gravity waves. For a stronger stratification, separation occurs, and a pair of vortices generally appears on the two sides of the obstacle, the size of which depends strongly on the flow parameters. The influence of gravity stratification is closely coupled to that of density. We examine conditions where the coupling impacts the pressure and the velocity fields, particularly the onset of gravity waves and vortex flow. Only a mild density gradient is needed for flow separation to occur. The influence of the amplitude and width of the obstacle is also investigated. Full article

The endothelial glycocalyx (GCX) plays a crucial role in vascular health and integrity and influences many biochemical activities through mechanotransduction, in which heparan sulfate (HS) plays a major role. Endothelin-1 (ET-1) is a potent vasoregulator that binds to the endothelin B receptor (ETB) on endothelial cells (ECs), stimulating vasodilation, and to the endothelin A receptor on smooth muscle cells, stimulating vasoconstriction. While the shear stress (SS) dependence of ET-1 and HS is well documented, there is limited research documenting the SS dependence of the ETB. Understanding the SS dependence of the ETB is crucial for clarifying the role of hemodynamic forces in the endothelin system. We hypothesize that GCX HS regulates the expression of the ETB on the EC surface in an SS-dependent manner. Human lung microvascular ECs were exposed to SS in a parallel-plate flow chamber for 12 h. Damage to the GCX was simulated by treatment with 15 mU/mL heparinase-III during SS exposure. Immunostaining and qPCR were used to evaluate changes in ET-1, ETB, and HS expression. Results indicate that ETB expression is SS sensitive, with at least a 1.3-fold increase in ETB protein expression and a 0.6 to 0.4-fold-change decrease in ETB mRNA expression under SS. This discrepancy suggests post-translational regulation. In some cases, enzymatic degradation of HS attenuated the SS-induced increase in ETB protein, reducing the fold-change difference to 1.1 relative to static controls. This implies that ETB expression may be partially dependent on HS-mediated mechanotransduction, though inconclusively. Furthermore, ET-1 mRNA levels were elevated two-fold under SS without a corresponding rise in ET-1 protein expression or significant impact from HS degradation, implying that post-translational regulation of ET-1 occurs independently of HS. Full article

Study design: The advent of the Matrix Wave^TM System (Depuy-Synthes)—a bone-anchored Mandibulo-Maxillary Fixation (MMF) System—merits closer consideration because of its peculiarities. Objective: This study alludes to two preliminary stages in the evolution of the Matrix Wave^TM MMF System and details its technical and functional features. Results: The Matrix Wave^TM System (MWS) is characterized by a smoothed square-shaped Titanium rod profile with a flexible undulating geometry distinct from the flat plate framework in Erich arch bars. Single MWS segments are Omega-shaped and carry a tie-up cleat for interarch linkage to the opposite jaw. The ends at the throughs of each MWS segment are equipped with threaded screw holes to receive locking screws for attachment to underlying mandibular or maxillary bone. An MWS can be partitioned into segments of various length from single Omega-shaped elements over incremental chains of interconnected units up to a horseshoe-shaped bracing of the dental arches. The sinus wave design of each segment allows for stretch, compression and torque movements. So, the entire MWS device can conform to distinctive spatial anatomic relationships. Displaced fragments can be reduced by in-situ-bending of the screw-fixated MWS/Omega segments to obtain accurate realignment of the jaw fragments for the best possible occlusion. Conclusion: The Matrix Wave^TM MMF System is an easy-to-apply modular MMF system that can be assembled according to individual demands. Its versatility allows to address most facial fracture scenarios in adults. The option of “omnidirectional” in-situ-bending provides a distinctive feature not found in alternate MMF solutions. Full article

This study assessed the viable and culturable microbial diversity that remained on equipment surfaces after hygiene procedures in Brazilian poultry and fish slaughterhouses. Food-contact surface samples were collected using sterile swabs in poultry (n = 50) and fish (Oreochromis niloticus, n = 50) slaughterhouses. The swab samples were used to prepare culture plates to recover viable and culturable cells. The grown plates were washed, and the total DNA of the cell suspension was extracted with a commercial kit. Sequencing of the total DNA extracted from cultures was targeted at the V3 and V4 regions of the 16S rRNA. DNA reads were analyzed by QIIME2 software, with results expressed in relative frequency (%RF). Alpha and beta diversity indexes were analyzed considering the spots of sample collection, type of industry, surfaces (smooth or modular), and materials (polypropylene, stainless steel, or polyurethane). The results showed that in the poultry slaughterhouse, the most abundant genera were Acinetobacter (27.4%), Staphylococcus (7.7%), and Pseudomonas (5.3%), while for the fish slaughterhouse, there was a higher abundance of Staphylococcus (27.7%), Acinetobacter (17.2%), and Bacillus (12.5%). Surface characteristics influenced the microbial diversity, with Acinetobacter spp. dominating modular surfaces and Staphylococcus spp. prevailing on smooth surfaces. The results obtained indicate there is an important resident microbiota that persists even after hygiene processes, and surface-specific cleaning strategies should be developed. Full article

This article presents a series of innovative systems developed through student laboratory projects, comprising two autonomous vehicles, a quadrupedal walking robot, an active ankle-foot orthosis, a ball-on-beam balancing mechanism, a ball-on-plate system, and a manipulator arm, all actuated by pneumatic artificial muscles (PAMs). Due to their flexibility, low weight, and compliance, fluidic muscles demonstrate substantial potential for integration into various mechatronic systems, robotic platforms, and manipulators. Their capacity to generate smooth and adaptive motion is particularly advantageous in applications requiring natural and human-like movements, such as rehabilitation technologies and assistive devices. Despite the inherent challenges associated with nonlinear behavior in PAM-actuated control systems, their biologically inspired design remains promising for a wide range of future applications. Potential domains include industrial automation, the automotive and aerospace sectors, as well as sports equipment, medical assistive devices, entertainment systems, and animatronics. The integration of self-constructed laboratory systems powered by PAMs into control systems education provides a comprehensive pedagogical framework that merges theoretical instruction with practical implementation. This methodology enhances the skillset of future engineers by deepening their understanding of core technical principles and equipping them to address emerging challenges in engineering practice. Full article

The bending of topological interlocking (TI) plates under point loading is not smooth; it is accompanied by developing lines of localization commensurate with the symmetry of the interlocking assembly. Furthermore, the developed stage of deflection is characterized by post-peak softening. This paper proposes a new concept that explains these experimentally observed phenomena. A new model considers that due to the absence of bonding between the blocks, they assume independent rotational degrees of freedom; this is missed in the traditional modeling of TI structures. The bending resistance of TI beams relies on the elasticity of the peripheral constraint (frame or post-tensioning cables) resisting the additional loading caused by the relative rotation of blocks—a phenomenon called elbowing. This is independent of the particulars of the shape of interlocking blocks, which makes it possible to model the deflection of the TI beams as the deflection of fragmented beams consisting of parallelepiped blocks with restricted out-of-beam relative displacements. The model demonstrates that the bending of TI beams produces the experimentally observed point deflection, which is considerably different from that of conventional beams. This is a consequence of independent block rotation and elbowing. It is shown that the other consequence of block rotation with elbowing is the force–deflection relationship exhibiting a post-peak softening (apparent negative stiffness). Based on the point deflection model, it is demonstrated that oscillations of TI blocks involve a unidirectional damping with discontinuous velocity dependence. This paper develops a model of such damping. The results are important for designing flexible topological interlocking structures with energy absorption. Full article

In this work, arc ion plating (AIP) was employed to deposit AlCrMoN coatings on cemented carbide substrates, and the effects of substrate bias voltages (−80 V, −100 V, −120 V, and −140 V) on the microstructures, mechanical properties, and tribological behaviors of the coatings were investigated. The results showed that all AlCrMoN coatings exhibited a single-phase face-centered cubic (FCC) structure with columnar crystal growth and excellent adhesion to the substrate. As the negative bias voltage increased, the grain size of the coatings first decreased and then increased, while the hardness and elastic modulus showed a trend of first increasing and then decreasing, with the maximum hardness reaching 36.2 ± 1.33 GPa. Room-temperature ball-on-disk wear tests revealed that all four coatings demonstrated favorable wear resistance. The coating deposited at −100 V exhibited the lowest average friction coefficient of 0.47 ± 0.02 and wear rate ((3.27 ± 0.10) × 10⁻⁸ mm³/(N∙m)), featuring a smooth wear track with minimal oxide debris. During the steady-state wear stage, the dominant wear mechanisms of the AlCrMoN coatings were identified as oxidative wear combined with abrasive wear. Full article

The geometric structure design of three-layer hollow fan blades is extremely complex, which is not only directly related to the blade quality and manufacturing cost but also has a significant impact on engine performance. Based on geometric algorithms and combined with design rules and process constraints, an intelligent design method for the geometric structure of three-layer hollow blades is proposed: A new cross-section curve design method based on a non-equidistant offset is presented to enable the rapid design of wall plate structure. An innovative parametric design method for the corrugation structure in cross-sections driven by process constraints such as diffusion bonding angle thresholds is put forward. The spanwise rib smoothing optimization is realized based on the minimum energy method with the corrugation angle change term. The cross-section densification design is carried out to improve the accuracy of wireframe structure and achieve the rapid solid modeling of hollow blades. Finally, the proposed methods are seamlessly integrated into the NX software (version 12), and a three-layer hollow fan blade intelligent design system is developed, which enables the automated design and modeling of the complex geometric structure of the hollow blade under an aerodynamic shape and a large number of design and process constraints. Full article

The damage location detection of the fiber-reinforced composite thin plate (FCTP) is studied through the curvature modal shape scanning method (CMSSM), utilizing the advantages of the sensitivity of curvature modal shapes to local stiffness changes and the high measurement accuracy of a laser vibrometer. Firstly, our research begins with the construction of a laser scanning frame model for the FCTP. Subsequently, during the analysis of modal shape data extraction principles, the two-dimensional five-spot-tripling surface smoothing method is developed, so that the quantitative index for damage location detection of the FCTP, i.e., the damage localization index, can be derived. The operating deflection shapes of the FCTP at different natural frequencies are obtained, and the self-developed laser scanning vibration testing system is employed to scan and measure the vibration. Then, a TC500 fiber/epoxy composite plate is utilized as an experimental object to perform a damage identification experiment. It has been proven that this approach can detect the fiber breakage location of the FCTP with high accuracy. Finally, the influence of parameters such as boundary constraint, excitation level, and laser scanning rate on the damage detection results is also discussed. Through studies on influencing parameters, practical guidance is provided for the application of the damage identification approach of the FCTP. Full article

Plasma arc welding (PAW) is commonly employed for welding medium and thick plates due to its capability of single-side welding and double-side forming. Ensuring welding quality necessitates real-time precise identification of the melting state. However, the intricate interaction between the plasma arc and the molten pool, along with substantial signal noise, poses a significant technical hurdle for achieving accurate real-time melting state identification. This study introduces a magnetically controlled method for identifying plasma arc melt-through, which integrates arc voltage and arc pool pressure. The application of an alternating transverse magnetic field induces regular oscillations in the melt pool by the plasma arc. The frequency characteristics of the arc voltage and pressure signals during these oscillations exhibit distinct mapping relationships with various fusion states. A hybrid feature extraction model combining gray correlation analysis (GRA) and the Pearson correlation coefficient (PCC) is devised to disentangle the nonlinear, non-smooth, and high-dimensional repetitive features of the signals. This model extracts features highly correlated with the fusion state to construct a feature vector. Subsequently, this vector serves as input for the fusion classification model, CNN-SVM, facilitating fusion state identification. The experimental results of melt-through under various welding speeds demonstrate the robustness of the proposed method for identifying melt-through through magnetic field-assisted melt pool oscillation, achieving an accuracy of 96%. This method holds promise for integration into the closed-loop quality control system of plasma arc welding, enabling real-time monitoring and control of melt pool quality. Full article

Background: Biochar has gained increasing attention for its potential benefits in improving animal health. Its physical and chemical properties depend on the starting biomass and production technology. This study investigates its functional properties versus bacteria. Methods: The morphology and physical properties of biochar from vine pruning were evaluated by SEM. The adsorption capacity for pathogenic E. coli F4+ and F18+ and probiotic microorganisms such as Lactobacillus sp. was assessed by plate count after contact with biochar. The growth activity on pathogenic and probiotic bacteria was tested after in vitro digestion. Results: Biochar from grapevine pruning did not maintain the original structure and showed both smooth and rough surfaces. The binding capacity varied across bacterial species. At concentrations of 20 mg/mL, up to 74% of E. coli adhered to the biochar surface, while the maximum adsorption rate of Lactobacillus sp. was around 38%. An inhibitory activity against E. coli (maximum reduction: 35%) and a growth-promoting effect for Lactobacillus sp. were observed (maximum promotion: 6%). Conclusions: These findings highlight the potential of biochar as a functional feed ingredient and that its functional properties are preserved after in vitro digestion. Full article

The Polydimethylsiloxane (PDMS) SlipChip is a microfluidic platform enabling fluid manipulation without pumps or valves, simplifying operation and reducing reagent use. High-viscosity silicone oils (e.g., 5000–10,000 cSt) improve sealing but frequently block microfluidic channels, reducing usability. In contrast, low-viscosity oils (50–100 cSt) reduce blockages but may compromise sealing. This study addresses these challenges by optimizing the viscosity of silicone oil and the curing conditions of PDMS. Low-viscosity silicone oil (50 cSt) was identified as optimal, ensuring smooth slipping and reliable sealing without blockages. Curing conditions were also adjusted to balance adhesion and stiffness as follows: lower temperatures (50–60 °C) enhanced van der Waals adhesion, while higher temperatures (80 °C) increased stiffness. A mixed curing approach (80 °C for the top layer and 60 °C for the bottom layer) further improved performance. Biocompatibility testing using human osteosarcoma cells demonstrated minimal cytotoxicity with 50 cSt oil, supporting cell viability (95%) comparable to traditional multiwell plates. These findings provide practical guidelines for fabricating reliable and biocompatible SlipChips. Full article

Silver-white, matte, smooth, and durable deposits of silver-rhenium, with thicknesses ranging from 2.0 to 13.7 μm and containing 0.15 to 13.5 wt.% Re, were obtained with a current efficiency of 66–98% from a developed dicyanoargentate–perrhenate bath based on a borate–phosphate–carbonate silver-plating electrolyte. This study was focused on the influence of bath composition, the [Ag(I)]:[ReO₄⁻] ratio, surfactant additives, applied current density, temperature, and stirring, on the alloys’ composition, structure, morphology, microhardness, adhesion, and porosity. A voltammetric analysis was conducted, considering the influence of ethanolamines on electrode processes. In baths with triethanolamine (TEA), coatings similar to a silver matrix with rhenium doped in mass fractions are likely achievable. Monoethanolamine (MEA) is recommended due to its process-activating properties. All coatings were nanocrystalline (τ = 28.5–35 nm). For deposits containing less than 10 wt.% Re, characteristic silver XRD peaks were observed, while for other deposits, additional peaks attributed probably to Re(VII) and Re(VI) oxides. A linear relationship H_v − τ^−1/2, typical for Hall–Petch plots, was obtained, confirming that grain boundaries play a crucial role in mechanical properties of coatings. The conditions for stable electrochemical synthesis of promising functional Ag-Re coatings of predetermined composition (0.7–1.5 wt.% Re) were proposed for practical use in power electronics and energy sectors for manufacturing electrical contacts operating across a wide temperature range. This was realized by deposition from an Ag-rich bath in the area of mixed electrochemical kinetics, at potential values corresponding to the region of half the limiting current: j = 2.5–6 mA cm⁻², t = 19–33 °C. Full article

Al-Cr-N ternary coatings were deposited on the surface of Cr12MoV alloy tool steel via multiarc ion plating technology. The microstructure and mechanical and tribological properties of these coatings were systematically characterized, analyzed, and compared with those of the uncoated substrate specimens. The results indicated that under optimal conditions, Al70Cr30 alloy was effectively ionized, leading to the formation of AlN and CrN phases between Al ions, Cr ions, and nitrogen atoms. These phases were uniformly distributed within the coating, forming an ordered lattice structure. At a bias voltage of −60 V, the deposited Al-Cr-N coating exhibited a uniform and smooth morphology. However, because of the inherent characteristics of arc deposition, droplets and craters were observed on the coating surface as a result of sputtering and back-sputtering effects. The average nanohardness of the Al-Cr-N ternary coating reached 23.8 ± 3.1 GPa, while the coefficient of friction stabilized at approximately 0.7 during the wear process, compared with around 0.8 for the uncoated Cr12MoV substrate. Compared with the uncoated Cr12MoV substrate, the Al-Cr-N coating demonstrated significantly enhanced hardness and wear resistance, thereby effectively improving the performance of Cr12MoV alloy tool steel. Full article