Search Results (68)

This work presents a novel type of soft reconfigurable mobile robot with multimodal locomotion, which is created using a controllable magneto-elastica-reinforced composite elastomer. The rope motor-driven method is employed to modulate magnetics–mechanics coupling effects and enable the magneto-elastica-reinforced elastomer actuator to produce controllable deformations. Furthermore, the 3D-printed magneto-elastica-reinforced elastomer actuators are assembled into several typical robotic patterns: linear configuration, parallel configuration, and triangular configuration. As a proof of concept, a few of the basic locomotive modes are demonstrated including squirming-type crawling at a speed of 1.11 $\mathrm{m}\mathrm{m}/\mathrm{s}$, crawling with turning functions at a speed of 1.11 $\mathrm{m}\mathrm{m}/\mathrm{s}$, and omnidirectional crawling at a speed of 1.25 $\mathrm{m}\mathrm{m}/\mathrm{s}$. Notably, the embedded magnetic balls produce magnetic adhesion on the ferromagnetic surfaces, which enables the soft mobile robot to climb upside-down on ferromagnetic curved surfaces. In the experiment, the inverted ceiling-based inverted crawling speed is 2.17 $\mathrm{m}\mathrm{m}/\mathrm{s}$, and the inverted freeform surface-based inverted crawling speed is 3.40 $\mathrm{m}\mathrm{m}/\mathrm{s}$. As indicated by the experimental results, the proposed robot has the advantages of a simple structure, low cost, reconfigurable multimodal motion ability, and so on, and has potential application in the inspection of high-value assets and operations in confined environments. Full article

The real-time rendering of large-scale curve-based surfaces (e.g., hair, fabrics) requires efficient handling of bidirectional curve-scattering distribution functions (BCSDFs). While curve-based material models are essential for capturing anisotropic reflectance characteristics, conventional prefiltering techniques encounter challenges in jointly resolving micro-scale BCSDFs variations with tangent distribution functions (TDFs) at pixel-level accuracy. This paper presents a real-time BCSDF filtering framework that achieves high-fidelity rendering without precomputation. Our key insight lies in formulating each pixel’s scattering response as a mixture of von Mises–Fisher (vMF) distributions, enabling analytical convolution between micro-scale BCSDFs and TDFs. Furthermore, we derive closed-form expressions for the integral of TDF-BCSDF products, avoiding the need for numerical approximation and heavy precomputation. Our method demonstrates state-of-the-art performance, achieving results comparable to 1000 spp Monte Carlo simulations under parallax-free conditions, where it improves the mean squared error (MSE) by one to two orders of magnitude over baseline methods. Qualitative comparisons and error analysis confirm both visual fidelity and computational efficiency. Full article

Manual grinding presents significant challenges for the task of high-precision shallow uniform grinding of curved rubber materials. The use of robots and grinding discs has the potential to substantially improve both the precision and efficiency of grinding tasks. To achieve this, a precise material removal model is essential to facilitate the optimization of robot grinding parameters and path planning. Nevertheless, most existing models primarily focus on metal materials or deep grinding depths, rendering them inapplicable to rubber materials. Therefore, this study investigates the contact mechanics during disc grinding of rubber materials and quantifies the distributions of grinding pressure and speed. Additionally, it evaluates the effects of different elastic deformation and wear stages on the grinding process, ultimately developing a material removal model for free-form rubber surfaces based on the Preston equation. The validity of the model is experimentally verified. Furthermore, the study shows that, when processing workpieces with different surface shapes, the study indicates a negative correlation between both the grinding width and the grinding pressure with the curvature radius. Full article

As the field of robotics advances swiftly, industrial automation has become prevalent in the realms of manufacturing and precision measurement. In robot measurement applications, the original path often originates from the discrete output of CAD models or point cloud data of vision systems, and its measurement path is a linear path composed of discrete feature points. Vibrations are generated by robots when passing through corners between adjacent linear segments. In order to reduce vibration, an algorithm for smoothing the robot’s measurement path based on multiple curves is proposed. Based on the proposed robot scanning measurement path generation algorithm, a robot scanning measurement path is generated. The position and attitude of the scanning path are represented as multiple curves using a position and attitude representation method based on multiple curves. The corners of the position curve and attitude curve are smoothed using a 5th-order B-spline curve. Based on the established robot position tolerance and attitude tolerance constraints and geometric continuity, the control points of the B-spline curve are solved, and corresponding position corner smooth B-spline curves and attitude corner smooth B-spline curves are constructed. Based on the geometric continuity, we use B-spline curves to replace the transition parts of adjacent position corner points and adjacent attitude corner points in the scanning path and then achieve the synchronization of robot position and attitude by the common curve parameter method. Finally, the effectiveness of our proposed path smoothing algorithm was verified through robot joint tracking experiments and scanning measurement experiments. Full article

The change in the surface properties of polymer materials used in an extracorporeal membrane oxygenation (ECMO) device due to nitric oxide (NO) treatment was characterized by zeta-potential and dynamic contact-angle measurements. FTIR-ATR was used to determine the stability of these effects during liquid contact. Polymethyl pentene (PMP), methyl methacrylate acrylonitrile butadiene styrene (MABS), and polyurethane (PU) were investigated. The polymer materials were treated with NO (1000 ppm) for 17 h. The samples for FTIR-ATR measurements were submerged in water or physiological sodium chloride solution for 120 and 240 h after the end of the gas treatment. PMP showed no changes at all. MABS showed decreased contact-angles and increased contact-angle hysteresis. In contrast, PU showed decreased contact-angles and a shift in its zeta-potential curve, indicating a more hydrophilic and acidic surface. The FTIR-ATR measurements showed a slight decrease in the signal intensities after liquid contact. The results indicated an improvement in the liquid contact properties of MABS and the PU due to increased surface hydrophilicity caused mainly by the adsorbed nitric acid (HNO₃) molecules formed by the NO treatment. The results presented in this paper point towards a simple and complication-free method of introducing NO into an ECMO circuit. Full article

Polymer corrosion inhibitors are reported to form dense films on carbon steel surfaces, and their thermostability enables survival in harsh downhole environments. In this paper, PEG-OTs was synthesized by mechanochemistry using ball mill by grafting tosyl on PEG. Using this solvent-free green chemistry, non-toxic PEG and PEG-OTs with various molecular weights (600, 2000, and 10,000 g/mol) were prepared and used as corrosion inhibitors. The corrosion inhibition performance of 5 × 10⁻³ mol/L inhibitors on Q235 carbon steel in 0.5 M HCl solution was investigated using static weight-loss, electrochemical impedance spectroscopy, polarization curves, SEM, and contact angle measurements. The results show that, after modification, PEG-OTs has an elevated corrosion inhibition effect compared to PEG. A maximum of 90% corrosion inhibition efficiency was achieved using static weight-loss. The morphology study shows that a dense film formed to protect carbon steel. Thanks to their polymeric structure, a higher molecular weight leads to better corrosion inhibition. Full article

In the field of Computer-Aided Geometric Design (CAGD), a proper model can be achieved depending on certain characteristics of the predefined blending basis functions. The presence of these characteristics ensures the geometric properties necessary for a decent design. The objective of this study, therefore, is to examine the generalized $\alpha$-Bernstein operator in the context of its potential classification as a novel blending type basis for the construction of Bézier-like curves and surfaces. First, a recursive definition of this basis is provided, along with its unique representation in terms of that for the classical Bernstein operator. Next, following these representations, the characteristics of the basis are discussed, and one shape parameter for $\alpha$-Bezier curves is defined. In addition, by utilizing the recursive definition of the basis, a de Casteljau-like algorithm is provided such that a subdivision schema can be applied to the construction of the new $\alpha$-Bezier curves. The parametric continuity constraints for $C^0$, $C^1$, and $C^2$ are also established to join two $\alpha$-Bezier curves. Finally, a set of cross-sectional engineering surfaces is designed to indicate that the generalized $\alpha$-Bernstein operator, as a basis, is efficient and easy to implement for forming shape-adjustable designs. Full article

The off-axis reflective optical system offers several advantages, including the elimination of central obstruction, zero chromatic aberration, and a compact structure. These features make it highly valuable in the domain of space remote sensing. Freeform surfaces transcend the limitations imposed by rotational symmetry, providing significant design flexibility that is particularly effective for correcting non-rotationally symmetric aberrations present in off-axis systems. In this paper, we propose the averaged seed curve extension (A-SCE) method, which facilitates the direct design of an initial structure for freeform off-axis reflective systems. Both focal and afocal off-axis four-mirror freeform optical systems are designed utilizing the A-SCE method, demonstrating an enhanced capability for initial structure design. The results indicate excellent optical performance while maintaining relatively loose processing and assembly tolerances for both systems, thereby enhancing the facilitation of practical implementation. Full article

Itraconazole (ITZ) is a broad-spectrum triazole antifungal agent suitable for the treatment of superficial and systemic mycoses. This study aimed to formulate, characterize, and evaluate the in vitro antifungal performance of single-jet electrospun itraconazole-loaded polyvinylpyrrolidone-based fibers. Fibrous mats were prepared under the following experimental conditions: 10, 12.5, and 15 cm needle–collector distance, 20 kV tension, and 1, 1.5, and 2 mL/hour flow rate. The fibers were characterized by SEM, DSC, FTIR, assays, disintegration tests, dissolution tests, and in vitro antifungal activity. Using a 2² factorial design, the effects of preparation variables on the characteristics of the fibrous sheets were described. The electrospinning process led to smooth-surfaced, randomly oriented, and bead-free fibers. The average fiber diameter ranged from 887 nm to 1175 nm. The scanning calorimetry of pure ITZ revealed a sharp endothermic melting point at a temperature of 170 °C, not present in the curves of the fibers. After 60 min, between 70 and 100% of ITZ was released. The antifungal assay revealed that the fibers inhibited the growth of Candida albicans and Candida parapyilosis. The obtained fiber mats prepared from the hydrophilic polymer presented almost instantaneous disintegration, with potential applications for rapid antifungal delivery in oral or topical pharmaceutical form. Full article

At present, most near-eye display devices adopt flat substrates, which have problems such as limited field of view (FOV) and bulky shape, while the curved structure is expected to expand the FOV with appropriate volume. In this paper, we propose a curved holographic augmented reality (AR) near-eye display system based on holographic optical element (HOE) with the ability to expand the FOV. The system includes a display source and a HOE with curved substrate. We analyze the system by exploiting the diffraction theory between plane and curved surface, and a layered and weighted FOV optimization method using particle swarm optimization algorithm is proposed to realize the optimization of the phase of freeform HOE. Numerical and experimental results show that the proposed curved holographic near-eye display system can realize cylindrical AR display and expand the FOV of the system. It is expected to be applied to the holographic AR near-eye display in the future. Full article

Biological warfare agents are infectious microorganisms or toxins capable of harming or killing humans. Francisella tularensis is a potential bioterrorism agent that is highly infectious, even at very low doses. Biosensors for biological warfare agents are simple yet reliable point-of-care analytical tools. Developing highly sensitive, reliable, and cost-effective label-free DNA biosensors poses significant challenges, particularly when utilizing traditional techniques such as fluorescence, electrochemical methods, and others. These challenges arise primarily due to the need for labeling, enzymes, or complex modifications, which can complicate the design and implementation of biosensors. In this study, we fabricated Graphene Quantum dot (GQD)-functionalized biosensors for highly sensitive label-free DNA detection. GQDs were immobilized on the surface of screen-printed gold electrodes via mercaptoacetic acid with a thiol group. The single-stranded DNA (ssDNA) probe was also immobilized on GQDs through strong π−π interactions. The ssDNA probe can hybridize with the ssDNA target and form double-stranded DNA, leading to a decrease in the effect of GQD but a positive shift associated with the increase in DNA concentration. The specificity of the developed system was observed with different microorganism target DNAs and up to three-base mismatches in the target DNA, effectively distinguishing the target DNA. The response time for the target DNA molecule is approximately 1010 s (17 min). Experimental steps were monitored using UV/Vis spectroscopy, Atomic Force Microscopy (AFM), and electrochemical techniques to confirm the successful fabrication of the biosensor. The detection limit can reach 0.1 nM, which is two–five orders of magnitude lower than previously reported methods. The biosensor also exhibits a good linear range from 10⁵ to 0.01 nM and has good specificity. The biosensor’s detection limit (LOD) was evaluated as 0.1 nM from the standard calibration curve, with a correlation coefficient of R² = 0.9712, showing a good linear range and specificity. Here, we demonstrate a cost-effective, GQD-based SPGE/F. tularensis DNA test suitable for portable electrochemical devices. This application provides good perspectives for point-of-care portable electrochemical devices that integrate sample processing and detection into a single cartridge without requiring a PCR before detection. Based on these results, it can be concluded that this is the first enzyme-free electrochemical DNA biosensor developed for the rapid and sensitive detection of F. tularensis, leveraging the nanoenzyme and catalytic properties of GQDs. Full article

A numerical investigation into the impact of the longitudinal position of the center of buoyancy on the total resistance of a passenger ship is conducted using the computational fluid dynamics software package STAR-CCM+. The modification of the hull form is performed using the CAESES software package, respecting the limitations on the longitudinal position of the center of buoyancy set by Flow Ship Design d.o.o. The total numerical uncertainty for the total resistance, sinkage, and trim angle of the original hull form is assessed within the verification study. The flow around the ship hull is analyzed in detail, including the determination of the wave pattern and free surface elevation as well as the hydrodynamic pressure and tangential stress distributions. The obtained values for total resistance, sinkage, and trim angle for all modified hull forms are compared. The study indicated that shifting the longitudinal position of the center of buoyancy by 0.4% can lead to a 2.11% reduction in total resistance compared to the original hull form. Resistance tests are conducted at two additional speeds to determine the resistance curve for the hull form with the most favorable total resistance characteristics. The results indicate that simple modifications of the hull form can lead to a reduction in the total resistance without necessitating complex optimization algorithms. Full article

FCPs (free-form concrete panels) can be made using reusable and easily customizable silicone molds tailored to the unique shape of each panel. CNC (Computer Numerical Control)-type rods move vertically to press the silicone plate and shape the lower curved surface. Silicone caps are attached to the ends of the rods to facilitate the formation of smooth curves. However, there is currently no fixing method for the silicone caps and the silicone plate, which makes them vulnerable to the lateral pressure exerted during concrete pouring. Therefore, the current study used magnetic force to improve the lower shape of free-form molds. To this end, a neodymium silicone cap was designed by adding a neodymium magnet to the upper surface of the silicone cap. Moreover, two types of silicone plates were developed for fixing: one type is IS-LSM (Iron Sheet–Silicone Mold), which includes an iron sheet, while the other type is IP-LSM (Iron Powder–Silicone Mold), which is made by mixing iron powder. To verify these two techniques, FCP manufacturing experiments were conducted. The experimental results indicated that IS-LSM had a broader error range than existing techniques, thus rendering it unusable, while IP-LSM yielded significant values. Consequently, a t-test was conducted to validate the data for IP-LSM at 30%, 50%, and 70%, and it was confirmed that the difference in error data was significant at a 95% confidence level. Future research in this area should investigate the addition of iron powder to the silicone plate and a side fixing method for the silicone mold. Such research would help advance the production technology of free-form concrete panels. Full article

In recent research in computer-aided geometric design (CAGD), one of the most popular concerns has been the creation of new basis functions for the Bézier curve. Bézier curves with high degrees often overshoot, which makes it challenging to maintain control over the ideal length of the curved trajectory. To get around this restriction, free-form surfaces and curves can be created using the Caputo Fabrizio basis function. In this study, the Caputo Fabrizio fractional order derivative is used to construct the Caputo Fabrizio basis function, which contains fractional parameter and shape parameters. The Caputo Fabrizio Bézier curve and surface are defined using the Caputo Fabrizio basis function, and their geometric properties are examined. Using fractional and shape parameters in the implementation of the Caputo Fabrizio basis function offers an alternative perspective on how the Caputo Fabrizio basis function can construct complicated curves and surfaces beyond a limited formulation. Curves and surfaces can have additional shape and length control by adjusting a number of fractional and shape parameters without affecting their control points. The Caputo Fabrizio Bézier curve’s flexibility and versatility make it more effective in creating complex engineering curves and surfaces. Full article

To enhance the wear resistance of artillery barrels in harsh environments, TaC and Ta/TaC coatings were prepared on 30CrNi2MoVA steel using double-glow plasma surface metallurgy technology. These coatings, of which their surfaces consisted of almost pure TaC phases, showed defect-free interfaces with the substrate. The Ta/TaC coating demonstrated excellent integration, forming a nearly homogeneous structure. The coatings exhibited a gradient cross-sectional hardness, affecting a depth of approximately 20 μm. The Ta transition layer significantly enhanced the microhardness and adhesive strength of the TaC coating, with about 16.7% and 68.5% increases in the Ta/TaC coating, respectively. Both coatings markedly improved the wear resistance, showing slight wear at room temperature and minor oxidative wear at high temperatures. The Ta/TaC coating had more stable friction coefficient curves and a lower specific wear rate, with an 11.4% wear rate of the substrate at 500 °C. Thermal mismatch and stress concentration under wear loads caused extensive cracks and edge chipping in the TaC coating. In contrast, the good compatibility between the Ta transition layer and the TaC layer allowed for cooperative deformation with the substrate, creating a plastic deformation zone that reduced internal stresses and stress concentration, maintaining the intact structure. This study provides insights into applying Ta/TaC coatings for artillery barrel protection and broadens the possible application scenarios of the preparation technology. Full article