Search Results (225)

Traditional approaches in tunnel lighting have been directed toward the installation of appropriate luminaires in the intermediate and transitional sections with the simple objective of diminishing the effect of delayed visual accommodation during daylight hours. Such efforts run in parallel with the target of keeping the huge electrical use at the lowest level. Nevertheless, inadequate attention has been conceded to the interior areas, whose noticeable longitude in several instances, and subsequently the duration of occupancy of the users, can produce discomfort in the majority of the tunnel or underground passageway. It is in this region where the flicker effect presents a more remarkable impact. Although such effect is in fact uncomfortable, the strategies to eliminate it efficiently have not been developed in depth and the result is still deserving, especially in terms of sustainability. The reasons for this neglect, as well as some particularities and solutions, are exposed and discussed in the present article. Specifically, it is proved that the use of sunlight can be an adequate initiative and a positive energy input into design and retrofit tunnels capable of hampering or totally avoiding such unwanted effect. The innovative tunnel geometry explained in this manuscript is not cylindrical, and it is not based in revolution forms. Thus, it prevents the appearance of such unnerving visual effects, which compromise sustainability and endanger security. We are in the position to explain how the vector field generated by the normal to the points of the novel surface displayed remains non-parallel, ensuring appropriate diffusivity and, consequently, an even distribution of radiated energy. In the same manner, the notion of the tunnel is extended from a linear system to a veritable network of galleries, which can traverse in space bi- or even three-dimensionally. Accordingly, we will offer diverse instances of junctions and splices that further enhance the permeability into the terrain, augmenting the resilience capabilities of this disruptive technology. With all the former, a net reduction of costs reaching 25% can be easily expected with revenues. Full article

With the development of science and technology, mobile robots are playing a significant role in the new round of world revolution. Mobile robots could serve as assistants or substitutes for humans across a wide range of applications. To enhance mobile robot automation, advanced motion planners must be integrated to handle diverse environments. Navigating complex maze environments is a key challenge for mobile robots in various practical scenarios. Therefore, this article proposes a novel hierarchical motion planner named the rapidly exploring random tree-based Gaussian process motion planner 2, which aims to tackle the motion planning problem for mobile robots in complex maze environments. Specifically, the proposed motion planner successfully combines the advantages of the trajectory optimisation motion planning method and sampling-based motion planning method. To validate the performance and practicability of the proposed motion planner, we tested it in a series of self-constructed maze simulations and applied it on a surface marine robot in a high-fidelity maritime simulation environment in the Robot operating system. Full article

Orthopedic implant technology has historically seen difficulties in attaining long-term stability and biological integration, leading to complications such as implant loosening, wear debris production, and heightened infection risk. Nanotechnology provides a revolutionary method for addressing these constraints through the introduction of materials characterized by exceptional biocompatibility, durability, and integration potential. Nanomaterials (NMs), characterized by distinctive surface topographies and elevated surface area-to-volume ratios, facilitate improved osseointegration and provide regulated medication release, thereby creating a localized therapeutic milieu surrounding the implant site. To overcome the long-standing constraints of conventional implants, such as poor osseointegration, low mechanical fixation, immunological rejection, and implant-related infections, nanotechnology is causing a revolution in the field of orthopedic research. NMs are ideally suited for orthopedic applications due to their exceptional features, including increased tribology, wear resistance, prolonged drug administration, and excellent tissue regeneration. Because of their nanoscale size, they can imitate the hierarchical structure of real bone, which in turn encourages the proliferation of cells, lowers the risk of infection, and helps with the mending of bone fractures. This article will investigate the wide-ranging possibilities of nanostructured ceramics, polymers, metals, and carbon materials in bone tissue engineering, diagnostics, and the treatment of implant-related infections, bone malignancies, and bone healing. In addition, this paper will provide a basic overview of the most recent discoveries in nanotechnology driving the future of translational orthopedic research. It will also highlight safety evaluations and regulatory requirements for orthopedic devices. Full article

Optimizing vertical-axis hydrokinetic turbines is essential to enhance their energy conversion efficiency and structural reliability, particularly for decentralized renewable energy applications. This study focuses on identifying the most effective turbine design by evaluating the influence of three key parameters: aspect ratio ($AR$), solidity ($\sigma$), and the index of revolution (I). Specifically, the study considers Gorlov-type vertical-axis turbines, known for their helical design and favorable hydrodynamic characteristics. To achieve this, fifteen turbine configurations were analyzed using a combination of two methods: response surface methodology (RSM) and multi-criteria decision matrices. Both methods converged on the same optimal turbine model, characterized by an I of 0.1, a $\sigma$ of 0.40, and an $AR$ of 1.0, demonstrating superior energy efficiency and structural robustness, as the design achieved a power coefficient ($C_p$) of 40.8% at a tip speed ratio ($TSR$) of 1.01. The integration of numerical simulations and experimental validation provides comprehensive insights into turbine behavior, ensuring reliability in practical applications. These findings advance hydrokinetic energy technologies by identifying configurations that optimize both performance and manufacturability. Full article

Volvariella volvacea endoglucanase EG1 was used to treat bleached softwood kraft pulp (BSKP) and hardwood pulp (BHKP) to improve the refinability and physical strength, as well as to reduce vessel picking in Eucalyptus pulp. The results indicated that BSKP was treated with an enzyme dosage of 3 U/g for 2 h at 12,000 refining revolutions, which increased the tensile index from 71.4 N·m/g to 86.7 N·m/g. For BHKP, treatment with 10 U/g of EG1 for 2 h at 15,000 refining revolutions improved the tensile index from the control of 47.7 N·m/g to 56.9 N·m/g. Vessel-removed and vessel-enriched fractions of Eucalyptus pulp were obtained by screening and treated with EG1, respectively. It was found that EG1-assisted refining increased the physical strength and surface strength of both pulp fractions, and the latter improved even more, with increases of 22.4% and 160%, respectively. Full article

This paper addresses inherent limitations in unmanned aerial vehicle (UAV) undercarriages hindering vertical takeoff and landing (VTOL) capabilities on uneven slopes and obstacles. Robotic landing gear (RLG) designs have been proposed to address these limitations; however, existing designs are typically limited to ground slopes of 6–15°, beyond which rollover would happen. Moreover, articulated RLG concepts come with added complexity and weight penalties due to multiple drivetrain components. Previous research has highlighted that even a minor 3-degree slope change can increase the dynamic rollover risks by 40%. Therefore, the design optimization of robotic landing gear for enhanced VTOL capabilities requires a multidisciplinary framework that integrates static analysis, dynamic simulation, and control strategies for operations on complex terrain. This paper presents a novel, hybrid, compliant, belt-driven, three-legged RLG system, supported by a multidisciplinary design optimization (MDO) methodology, aimed at achieving enhanced VTOL capabilities on uneven surfaces and moving platforms like ship decks. The proposed system design utilizes compliant mechanisms featuring a series of three-flexure hinges (3SFH), to reduce the number of articulated drivetrain components and actuators. This results in a lower system weight, improved energy efficiency, and enhanced durability, compared to earlier fully actuated, articulated, four-legged, two-jointed designs. Additionally, the compliant belt-driven actuation mitigates issues such as backlash, wear, and high maintenance, while enabling smoother torque transfer and improved vibration damping relative to earlier three-legged cable-driven four-bar link RLG systems. The use of lightweight yet strong materials—aluminum and titanium—enables the legs to bend 19 and 26.57°, respectively, without failure. An animated simulation of full-contact landing tests, performed using a proportional-derivative (PD) controller and ship deck motion input, validate the performance of the design. Simulations are performed for a VTOL UAV, with two flexible legs made of aluminum, incorporating circular flexure hinges, and a passive third one positioned at the tail. The simulation results confirm stable landings with a 2 s settling time and only 2.29° of overshoot, well within the FAA-recommended maximum roll angle of 2.9°. Compared to the single-revolute (1R) model, the implementation of the optimal 3R Pseudo-Rigid-Body Model (PRBM) further improves accuracy by achieving a maximum tip deflection error of only 1.2%. It is anticipated that the proposed hybrid design would also offer improved durability and ease of maintenance, thereby enhancing functionality and safety in comparison with existing robotic landing gear systems. Full article

The design and operating regime of centrifugal fans operating with contaminated flows must consider the influence of different geometric parameters and flow dynamics design variables on fan wear. The influence of fan rotation speed and blade angle of attack on the erosion wear they may experience when moving fluids contaminated with solid particles is especially relevant. A method is proposed for performing experimental tests that emulate centrifugal fans using a slurry bucket installation, at tangential velocities of 2, 4, and 6 m/s and fluid incidence angles of 16, 22, and 28 degrees. An equation for cumulative wear is found, in which the independent variables incidence angle and linear velocity have a linear and quadratic influence, respectively. It can be specified that when the fan operates at revolutions between 814 and 815 rpm, for a tangential speed of 2 m/s and a flow rate of 20.16 m³/h, an accumulated wear of 1.3124 mg/g is recorded, caused by the impact of solid particles transported by the flow that could impact the surface of the blade when the angle is 22°24′. Full article

As CMOS technology continues to downsize to the nanometer range, the exponential growth predicted by Moore’s Law has been significantly decelerated. Doubling chip density in the two-dimensional domain will no longer be feasible without further device downsizing. Meanwhile, emerging new device technologies, which may be incompatible with the mainstream CMOS technology, offer potential performance enhancements for system integration and could be options for a More-than-Moore system. Additionally, the explosive growth of artificial intelligence (AI) demands ever-high computing power and energy-efficient computing platforms. Heterogeneous multi-chip integration, which combines diverse components or a larger number of functional blocks with different process technologies and materials into compact 3D systems, has emerged as a critical pathway to overcome the performance limitations of monolithic integrated circuits (ICs), such as limited process/material options, low yield, and multifunctional design complexity. Furthermore, it sustains Moore’s Law progression for a further smaller footprint and higher integration density, and it has become pivotal for “More-than-Moore” strategies in the next CMOS technology revolution. This approach is also crucial for sustaining computational advancements with low-power dissipation and low-latency interconnects in the coming decades. The key techniques for heterogeneous wafer-to-wafer bonding involve both copper-to-copper (Cu-Cu) and dielectric-to-dielectric bonding. This review provides a comprehensive comparison of recent advancements in Cu-Cu bonding techniques. Major issues, such as plasma treatment to activate bonding surfaces, passivation to suppress oxidation, Cu geometry, and microstructure optimization to enhance interface diffusion and regrowth, and the use of polymers as dielectrics to mitigate contamination and wafer warpage, as well as pitch size scaling, are discussed in detail. Full article

Immunotherapies targeting the programmed cell death-1 ligand 1 (PD-L1) and programmed cell death 1 (PD-1) pathway sparked a revolution in cancer treatment. These breakthrough therapies work by disrupting the interaction between PD-1—expressed on T cells—and its ligand PD-L1, commonly found on the surface of cancer cells. By using monoclonal antibodies to block this binding, the immune system is unleashed to fight cancer more effectively. However, PD-L1’s role extends far beyond immune evasion. When situated on cancer cells, PD-L1 transmits inhibitory signals through PD-1, silencing the effector functions of T cells. However, PD-L1 also engages in reverse signaling, also called intrinsic signaling, delivering intracellular instructions that contribute to cancer cell survival, even in the absence of PD-1 binding. This signaling cascade shields cancer cells from apoptosis, drives proliferation, regulates DNA damage responses, and even functions as a co-transcriptional transactivator, amplifying cancer’s ability to thrive. The intricate mechanisms behind PD-L1’s intrinsic signaling are under intense investigation. In this review, we provide a historical perspective on the discoveries leading to PD-L1’s structure, signaling motifs, and interacting partners, shedding light on its multifaceted roles and the promising therapeutic possibilities ahead. Full article

Bearing steels are frequently used in highly loaded components, such as roller bearings, due to their excellent hardenability and wear resistance. Microstructure, hardness, and residual stress distribution of the bearings significantly affect the wear resistance of the parts. In the present study, experiments investigated the effects of austenitizing temperature (850, 900, and 950 °C), with or without cryogenic treatment, and induction hardening treatment (9 and 12 kW) on the microstructure, microhardness, the amount of retained austenite, surface residual stress, and wear behavior of JIS SUJ3 steel. The experimental results revealed that the austenitized specimens’ microstructure consisted of martensite, retained austenite, and dispersed granular alloy carbide exhibiting high hardness. After cryogenic or induction hardening treatment, the surface residual stress of austenitized specimens exhibited compressive stress rather than its original tensile stress state. The induction hardening treatment can significantly increase the microhardness of austenitized specimens, followed by quenching. Furthermore, the induction-hardened surface possessed less retained austenite. For practical industrial applications, a prior austenitizing heat treatment at 950 °C followed by hardening with an induction power of 12 kW was the optimal parameter for JIS SUJ3 bearing steel. The maximum microhardness and surface residual stress were 920 HV_0.3 and −1083 MPa, respectively, while the lowest weight loss was 0.5 mg after the 10,000-revolution wear test. Full article

Silk fibroin, a biocompatible and flexible biopolymer derived from Bombyx mori silkworms, has shown promise in bioelectronics, due to its adjustable dielectric properties. This study investigates the influence of spin coating parameters on the optical, electrical, and dielectric properties of thin silk fibroin films. Silk fibroin solutions were spin coated onto indium tin oxide (ITO)/glass substrates at speeds ranging from 1000 to 7000 revolutions per minute (RPM), resulting in films with thicknesses that varied from 264.8 nm to 81.9 nm. Atomic force microscopy analysis revealed that the surface roughness remained consistent at approximately 1.5 nm across all the spin coating speeds, while the film thickness decreased with the increasing spin speed. Ultraviolet (UV)–visible spectroscopy showed that the transmittance at 550 nm increased from 81.2% at 1000 RPM to 93.8% at 7000 RPM, and the optical bandgap widened from 3.82 eV at 1000 RPM to 3.92 eV at 7000 RPM, which was attributed to reduced molecular packing and quantum confinement effects. Electrical characterization showed that thinner films (a spin speed of 5000–7000 RPM) exhibited a 15-fold increase in the leakage current, rising from 2.99 pA at 1000 RPM to 44.9 pA at 7000 RPM, and a decrease in resistance from 334 GΩ at 1000 RPM to 22.2 GΩ at 7000 RPM. The capacitance–voltage measurements indicated a 4-fold increase in voltage-dependent capacitance for thinner films, with capacitance values increasing from 36 pF at 1000 RPM to 176 pF at 7000 RPM. Dielectric loss analysis revealed that thinner films experienced higher energy dissipation at low frequencies (tan δ of 0.041 at 0.01 MHz for 7000 RPM), but lower losses at high frequencies (tan δ of 0.123 at 1 MHz for 7000 RPM). These findings emphasize the importance of film thickness control in optimizing the performance of silk fibroin-based bioelectronic devices. Full article

Traditional revolute clearance joints assume that the shape of the contact surface of the joint is regular and ignores the effects of wear, which reduces the prediction accuracy of dynamics models. To accurately describe the collision behavior of the motion pair, an Archard formula was applied to construct a wear clearance model. Based on the absolute node coordinate method, multi-body dynamics modeling, wear prediction, and chaotic identification analysis methods for a flexible multi-link mechanism with clearance considering wear effects were proposed. The research results indicate that wear exacerbates the irregularity of the clearance surface contours, leading to increased instability in the dynamic response and the reduced motion accuracy of the mechanism. Compared with clearance size, driving speed has a more significant impact on the chaotic behavior of the system. For high-speed conditions, maintaining the clearance size within approximately 0.1 mm is beneficial for system stability, although this requirement poses challenges for cost control in manufacturing. This study provides a theoretical foundation for wear prediction and stability optimization of high-precision multi-link mechanisms. Full article

In the present investigation, high stability Vitreloy Zr₄₄Ti₁₁Cu₁₀Ni₁₀Be₂₅ bulk metallic glass has been subjected to severe shear deformation by high-pressure torsion for 0.1 revolutions under an applied pressure of 4 and 8 GPa. The fully glassy nature of the as-cast glass has been confirmed by X-ray powder diffraction and differential scanning calorimetry. Deformation-induced surface features on an internal plane of the deformed disk-shaped specimens were studied in detail at the macroscopic level by optical reconstruction method and at microscopic scales by white-light optical profilometry. Shear and compressive strain components were measured based on surface changes and it was determined that compressive strain gradient with 0.2–0.4 strain change builds up toward the disk edge, while only part of the nominal shear deformation occurs in the disk interior. The effect of strain localization in the Vitreloy bulk metallic glasses has been quantified by a surface distortion model based on simple shear. The model was then validated experimentally by the reconstructed z-profiles. Full article

Robotic grinding serves as a pivotal embodiment and key technological support of Industry 4.0. Elucidating the influence of robotic grinding parameters on the material removal depth (MRD) of 42CrMo steel and optimizing these parameters are critical to enhancing grinding efficiency and quality. In this study, the influences of revolution speed, feed speed, grinding force, and grit designation on MRD and surface Vickers hardness of 42CrMo steel were investigated by using an adaptive electro-hydraulic-actuated triangular abrasive belt in robot grinding. A predictive model for MRD of 42CrMo steel has been established using the orthogonal central composite design method. The results indicated that as the revolution speed or grinding increases, both MRD and surface hardness increase. However, as the revolution speed surpasses 4000 RPM or the grinding force exceeds 60 N, the increase of MRD becomes slower due to the increase in surface hardness. Both the MRD and surface hardness decrease continuously as the feed speed increases, and once it exceeds 15 mm·s⁻¹, the decrease of the MRD becomes slow. The rise in grit designation of the abrasive belt makes the MRD reduce gradually while the surface hardness rises slightly. The correlation coefficient of the predictive model is 0.9387, and the relative error between the predicted and experimental MRD is within 10%, indicating a relatively high accuracy. At the optimal grinding parameters (grinding force of 81 N, revolution speed of 4739 RPM, and feed speed of 7.6 mm·s⁻¹), the maximum MRD of 42CrMo steel achieved by an abrasive belt of 60 grit designation is 0.934 mm. This work provides a basis for high-precision robot abrasive belt grinding of 42CrMo steel. Full article

Autonomous vehicles (AVs) and shared mobility constitute two of the “Three Revolutions” that portend major changes to surface transportation. AVs promise to reduce accidents, expand accessibility, and decrease congestion, while shared mobility provides the benefits of automotive transportation without requiring the purchase of a vehicle or the ability to drive it. Despite great promise to alleviate the negative externalities imposed by transportation, there remains much to be understood about the combined diffusion and impact of AVs and shared mobility. There is little demonstrated experience and application of AVs to the public, and how and where people would use automated shared mobility relative to their current travel is largely unknown. This study advances our understanding by utilizing an intercept survey of 232 respondents in Ann Arbor, Michigan who had made a discretionary trip to one of two central and two suburban locations. The novel approach of using intercept surveys allows us to gather more valid data about the willingness of respondents to replace the mode they just used for either a privately owned or a shared AV and do so for the trip purpose most conducive to using such a vehicle. We incorporate descriptive and spatial analyses and then utilize multinomial logit models to predict the factors influencing the encouragement or discouragement of substituting a private and a shared AV for their previous trip. We found that active mobility and transit trips work in competition with private AVs, while youth encourages interest. Meanwhile, active mobility, increasing age, and one of our measures of density discourage interest, while female respondents and the same measure of density increase interest. The results suggest that future efforts to facilitate the adoption of shared AVs target areas of the city that are relatively dense and residents in these areas where a shared AV would enhance individuals’ mobility. Full article