Search Results (3,414)

Magnetorheological elastomers (MREs) are smart composite materials with tunable mechanical properties by ferromagnetic particle interactions. This study applied the microstructure-based dipole and Maxwell methods to evaluate the magneto-mechanical coupling and magnetostrictive responses of MREs, focusing on various particle distributions. The finite element modeling of representative volume elements with fixed volume fractions revealed that the straight chain microstructure exhibits the most significant magnetostrictive effect due to its low initial shear stiffness and significant magnetic force contributions. For particle separations exceeding three radii, the dipole and Maxwell methods yield consistent results for vertically or horizontally aligned particles. For particle separations greater than three radii, the dipole and Maxwell methods produce consistent results for vertically and horizontally aligned particles. However, discrepancies emerge for angled configurations and complex microstructures, with the largest deviation observed in the hexagonal particle distribution, where the two methods differ by approximately 27%. These findings highlight the importance of selecting appropriate modeling methods for optimizing MRE performance. Since anisotropic MREs with straight-chain alignments are the most widely used, our results confirm that the dipole method offers an efficient alternative to the Maxwell method for simulating these structures. Full article

In the vertical parking process, the issue of turning in place due to discontinuities in path curvature is addressed by proposing an optimal reference path planning method based on circular arcs, straight lines, and a multi-objective evaluation function. This method first analyzes the obstacle avoidance constraints between the vehicle’s outer contour and the parking space, as well as the vehicle’s kinematic constraints. The feasible driving region’s upper and lower boundaries are determined by tangent circular arcs and straight lines. Subsequently, a multi-objective evaluation function is designed, which integrates path curvature, adjustable margins at any given moment, and path length, to obtain the optimal circular arc and straight line combination within the feasible region. Finally, the path is fitted using a polynomial curve to form the optimal reference path. Simulation results demonstrate that the planned path satisfies both the continuity of path curvature and the vehicle’s kinematic constraints. Full article

With the rapid development of geographic information technology, the expression of topographical spatial semantic relationships has become a research hotspot in the field of intelligent geographic information systems. Geographical spatial semantic relationships refer to the spatial relationships and inherent meanings between geographical entities, including topological relationships, metric relationships, etc. This study proposes a novel method of viewshed analysis, which solves the limitation of treating the viewshed as a unified unit in traditional viewshed analysis by decomposing the viewshed into multiple viewsheds and quantifying their spatial semantic relationships. The method uses a DBSCAN clustering algorithm with terrain adaptability to divide a viewshed into spatially different viewsheds and characterizes these viewsheds through a systematic measurement framework, including azimuth, area, and sparsity. The method was applied to a case study of Purple Mountain in Nanjing. The experiment used 12.5 m accuracy topographic data from Purple Mountain, and two observation points were selected. For the first observation point near the mountain park, during the DBSCAN clustering partition of the viewshed, the number of clusters and the number of noise points were compared with determine the neighborhood radius of 18 m and the minimum sample point number of 4. Five viewsheds were successfully generated, with the largest viewshed having 468 visible points and the smallest only 16, located in different locations from the observer, reflecting the spatial variability of terrain features. All viewsheds are basically distributed to the north of the observer, two of which also share the northeast 87° direction with the observer in a straight line distribution but at different distances. In three-dimensional space, the distance between the two viewsheds is 317.298 m. Azimuth angle verification showed significant aggregation in the northeast direction. The second point is near the ridgeline, where one viewshed accounts for 87.52% of the total viewshed, showing significant visual effects. One viewshed is 3121.113 m away from the observer, with only 113 visible points, and is not located at a low altitude, so it is suitable for a long-distance fixed-point intermittent observation. The experimental results of the two observation points reveal the directional dominance and distance stratification of viewshed spatial relationships. This paper proposes a model to express topographical viewshed spatial relationships. The model analyzes and describes the spatial features of the viewshed through quantitative and qualitative methods. These metric features provide a basis for constructing spatial topological relationships between observation points and viewsheds, helping optimize viewpoint selection and enhance landscape planning. Compared with traditional methods, the proposed method significantly improves the resolution of spatial semantic relationship expression and has practical application value in fields such as archaeology, tourism planning, and urban design. Full article

Road horizontal curves, which significantly influence drivers’ visual search behavior and are closely linked to traffic safety, also constitute a crucial factor in sustainable road traffic development. This paper uses simulation driving experiments to explore the dynamic response characteristics of 27 typical subject drivers’ visual search behavior regarding road horizontal curve radius. Results show that in a monotonous, open road environment, the driver’s visual search is biased towards the inside of the curve; as the radius increases, the 85th percentile value of the longitudinal visual search length gradually increases, the 85th percentile value of the horizontal search angle gradually decreases, the 85th percentile value of vehicle speed gradually increases, and the dispersion and bias of the gaze points gradually decrease. The search length, horizontal angle, and speed approach the level of straight road sections (380 m, 10° and 115 km/h, respectively). When R ≥ 1200 m, a driver’s dynamic visual search range reaches a stable distribution state that is the same as that of a straight road. A dynamic visual search range distribution model for drivers on straight and horizontal curved road sections is constructed. Based on psychological knowledge such as attention resource theory and eye–mind theory, a human factor engineering explanation was provided for drivers’ attention distribution and speed selection mechanism on road horizontal curve sections. The research results can provide theoretical references for the optimization design of road traffic, decision support to improve the driver training system, and a theoretical basis for determining the visual search characteristics of human drivers in autonomous driving technology, thereby promoting the safe and sustainable development of road traffic. Full article

Bore deterioration phenomena, such as surface ablation, wear, aluminum deposition, and structural bending, severely restrict the service life and performance of electromagnetic launchers. Efficient bore inspection is necessary to study the deterioration mechanism, guide design, and health management. In this paper, an inspection system for electromagnetic launchers is presented which utilizes structured light scanning, time-of-flight, and laser alignment methods to acquire bore laser point clouds, and ultimately extracts the surface deformation of rails and insulators, as well as the straightness of the bore, through the registration of point cloud data. First, the system composition and detection principles are introduced. Second, the impacts of the detection device’s attitude deflection are analyzed. Next, focusing on the key registration issue of laser point clouds, a coarse registration method is proposed which utilizes the arc features of the rail by combining circle and parabola equations, thereby maximizing registration efficiency. Finally, the trimmed iterative closest-point (TrICP) algorithm is employed for fine registration to handle non-axisymmetric bore deformations. The experimental results show that the proposed method can detect bore surface deformation and straightness efficiently and precisely. Full article

The present study employs numerical simulation to analyze the behavior of gas hydrate particles in bending pipelines, focusing on the influence of swirl flow on particle deposition under varying bending angles, pipe-to-diameter ratios, Reynolds numbers, and twist rates. Results indicate that larger bending angles, smaller twist rates, and higher Reynolds numbers produce stronger swirl flows at pipe entry and sustain higher swirl numbers along the pipeline. Conversely, larger pipe-to-diameter ratios result in greater swirl number variations, slower attenuation, and weaker outflow. Moreover, the phenomenon of hydrate particle deposition is more serious in the straight pipe section. Particle retention at the pipe outlet is 1.5 times higher than in the bending section. The bent pipe is more conducive to the flow of particles. For instance, with a bend rate increasing from 1 to 4, the swirl number decreases by 57.49%. Additionally, the deposition rate of particles is reduced at higher Reynolds numbers, with rates falling below 1% at a Reynolds number of 20,000. These findings highlight the need to optimize swirl flow parameters to reduce hydrate deposition, preventing blockages and improving pipeline safety in industrial applications. Full article

A fault-tolerant collaborative control strategy for four-wheel-drive electric vehicles is proposed to address hidden safety issues caused by one or more in-wheel motor faults; the basic design scheme is that the control system is divided into two layers of motion tracking and torque distribution, and three systems, including driving, braking, and front-wheel steering are controlled collaboratively for four-wheel torque distribution. In the layer of motion tracking, a vehicle model with two-degree-of-freedom is employed to predict the control reference values of the longitudinal force and additional yaw moment required; four types of sensors, such as wheel speed, acceleration, gyroscope, and steering wheel angle, are used to calculate the actual values. At the torque distribution layer, SSOD and MSCD distribution schemes are designed to cope with two operating conditions, namely sufficient and insufficient output capacity after local hub motor failure, respectively, focusing on the objective function, constraints, and control variables of the MSCD control strategy. Finally, two operating environments, a straight-line track, and a DLC track, are set up to verify the effectiveness of the proposed control method. The results indicate that, compared with traditional methods, the average errors of the center of mass sideslip angle and yaw rate are reduced by at least 12.9% and 5.88%, respectively, in the straight-line track environment. In the DLC track environment, the average errors of the center of mass sideslip angle and yaw rate are reduced by at least 6% and 4.5%, respectively. The proposed fault-tolerant controller ensures that the four-wheel-drive electric vehicle meets the requirements of handling stability and safety under one or more hub motor failure conditions. Full article

With the implementation of strict emission regulations, new energy technologies are widely used in the field of maritime transportation. Fuel cells can be used as the power sources of ships due to the advantages of high efficiency, low noise and zero emissions. In this study, a three-dimensional non-isothermal numerical model of a high temperature proton exchange membrane fuel cell (HT-PEMFC) is established and used to investigate the effect of a flow field with baffles on cell performance. The effects of the number, height and length of baffles in the flow field on the species concentration distribution, current density and power density are comprehensively studied. Compared with the traditional straight channel, the baffles in the channel can effectively improve cell performance. When the number of baffles is nine, the height of the baffles is 0.75 mm and the length of the baffles is 1 mm, the current density is increased from 1.390 A/cm² to 1.524 A/cm² at a voltage of 0.4 V, which is an increase of 9.64%. This study can provide guidelines for flow channel design. Full article

The shaping process is recognized as a crucial step in the manufacturing of green tea. However, its influence on aroma quality remains unclear. In this study, the effects of four shaping techniques, including flat green tea (FGT), straight green tea (SGT), phoenix green tea (PGT), and curled green tea (CGT), on the aroma quality and volatile metabolites of green tea were investigated by gas chromatography electronic nose (GC-E-Nose) and gas chromatography–tandem mass spectrometry (GC-MS/MS). The findings indicated that distinct shaping processes significantly influenced the development of the aroma quality and aroma components of green tea. The PGT processing facilitated the attainment of superior aroma quality of green tea. In total, 60 volatile components were identified by GC-MS/MS, with 54 of these compounds being consistently detected across four different shaping techniques. In particular, the PGT processing method was effective in yielding elevated levels of alcohols, esters and ketones. Moreover, 20 key odorants were screened out, with (E,E)-2,4-decadienal, (E,E)-2,4-nonadienal, phenylethyl alcohol, and benzeneacetaldehyde proven to be substantial contributors to the overall aromas of green tea under diverse shaping procedures. These key odorants were primarily derived from lipid degradation and the Maillard reaction. GC-E-Nose served as a significant adjunct to sensory evaluation, enabling the swift differentiation of green tea samples that have undergone various shaping processes. These findings offer both theoretical and technical perspectives that may guide the creation of innovative green tea products distinguished by their unique shapes. Full article

Storage ring X-ray light sources, which hold the great promises of high flux, high average brilliance, high stability, continuously adjustable spectra, and simultaneous multiple end-stations operations, have become indispensable tools for frontier research in diverse fields from materials science, condensed matter physics, chemistry, to life science, etc. Based on the double double-bend achromat (DDBA) lattice structure, an intermediate-energy electron storage ring with circumference of 288 m, emittance of 2.57 nm, is designed for dedicated materials research. Each cell of the storage ring consists of a 6.2 m-long straight section and a 1.86 m-short straight section, allowing more insertion devices to be accommodated in the entire ring. This lattice shows great nonlinear dynamic performances of large dynamic aperture and large local momentum aperture. Furthermore, the intra-beam scattering (IBS) effects under several circumstances, are also negligibly small. Full article

To investigate the influence of shape effects on the tensile strength of rocks, splitting tests were conducted on disc specimens with the same thickness-to-diameter ratio but different diameters using physical similarity simulation and numerical simulation experiments. Additionally, finite element analysis software was employed to perform numerical simulation tests on two types of dumbbell-shaped specimens involved in direct tensile tests of rocks. This study revealed that when the thickness-to-diameter ratio is fixed at 0.5, the splitting tensile strength decreases gradually as the specimen diameter increases from 30 mm to 110 mm. This trend can be well fitted using a power function. The tensile strength measured from direct tensile tests on the two types of dumbbell-shaped specimens shows a slight decreasing trend as the diameter of the central effective test area decreases. Moreover, the measured tensile strength is lower than the actual tensile strength. The test results for disc specimens are the closest to the actual tensile strength, followed by arc-transition dumbbell-shaped specimens, and lastly, straight-transition dumbbell-shaped specimens. The correlation coefficients between the test results and the actual tensile strength for the three types of specimens are also provided. Full article

This study aimed to determine whether there are relationships between vertical facial patterns, cervical posture, and cervical curvature types. Ninety-two adult females with skeletal Class I relationships were retrospectively analyzed and divided into hypodivergent, normovergent, and hyperdivergent groups based on the mandibular plane angle to the nasion–sella line. Variables representing craniocervical posture (sagittal vertical axis, SVA; cervical inclination angle, CIA) and cervical curvature were measured. Differences in craniocervical posture among the groups were assessed. Cervical curvatures were classified into lordotic, straight, kyphotic, or sigmoid categories. The distribution of cervical curvature types among the groups was compared, and correlations between vertical facial patterns, craniocervical postures, and cervical curvature measurements were calculated. The results indicated that the hyperdivergent group exhibited increased SVA and decreased CIA compared to the normovergent and hypodivergent groups. Significant differences in cervical curvature types were observed among the groups. Lordotic curvature was most common in the normovergent group, while straight curvature was predominant in the hypodivergent and hyperdivergent groups. A significant correlation was found between an increased mandibular plane angle and a forward head position (increased SVA and decreased CIA). In conclusion, there are relationships between vertical facial patterns, cervical posture, and cervical curvature types. Therefore, careful assessment of craniocervical posture and cervical curvature is necessary in lateral cephalograms for orthodontic evaluation. However, cervical curvature measurements show minimal correlation with the mandibular plane angle. Full article

Edge detection is essential for numerous applications in various engineering and scientific fields, including photogrammetry and computer vision. Edge detection can be applied to a variety of 2D and 3D data types, enabling tasks like feature extraction, object recognition and scene reconstruction. Currently, 2D edge detection in image data can achieve high accuracy through various automated methods. At the same time, edge detection in 3D space remains a challenge due to the computational demands and parameterization of existing algorithms. However, with the growing volume of data, the need for automated edge extraction that delivers high accuracy and reliable performance across diverse datasets has become more critical than ever. In this context, we propose an algorithm that implements a direct method for automated 3D edge detection in point clouds. The suggested method significantly aids architects by automating the extraction of 3D vectors, a process that is traditionally time-consuming and labor-intensive when performed manually. The proposed algorithm performs edge detection through a five-stage pipeline. More specifically, it utilizes the differences in the direction of normal vectors to identify finite edges. These edges are afterwards refined and grouped into segments which are then fitted to highlight the presence of 3D edges. The proposed approach was tested on both simulated and real-world data with promising results in terms of accuracy. For the synthetic data, the proposed method managed to detect 92% of the straight edges for the higher density meshes. Full article

Conventional hair-straightening methods that use chemical treatments to break disulfide bonds cause severe damage to the hair shaft, leading to weakened hair that is prone to reverting to its curly form in high humidity. Therefore, a unique haircare coating technology is required to protect hair integrity and provide a long-lasting straightening effect. Herein, we designed a hair-straightening technology by integrating a nature-inspired polyphenol–inorganic sulfate (PIS) redox agent into formulated shampoo, which achieves a desirable straightening effect through sulfate-induced disulfide breakage while preserving hair integrity through a polyphenol-reinforced structure. The interaction between polyphenols and residual thiols from the straightening process maintained a long-lasting straight hair structure and hair strength. Ellman’s assay showed a lower free thiol content from reductant-induced damaged keratin in PIS shampoo-treated hair than in sulfate-treated hair as the polyphenol–thiol bond was formed through the Michael addition reaction, thereby restoring the natural structure of the hair and enhancing its mechanical properties. Owing to the polyphenol coating, PIS shampoo-treated hair exhibited an antistatic effect and high hydrophobicity, indicating healthy hair. Furthermore, the polyphenol coating effectively scavenged radical oxygen species (ROS) in the hair, thereby improving damage protection. Thus, PIS shampoo offers an alternative approach for effective hair straightening. Full article

Path planning for intelligent semi-trailers encounters numerous challenges in complex traffic conditions. Serious consequences, such as vehicle rollover, may occur when the traffic conditions change. Therefore, it is vital to consider both the surrounding dynamic traffic conditions and the vehicle’s roll stability during the lane-changing process of intelligent semi-trailers. We propose an innovative path-planning method tailored for intelligent semi-trailers. This path-planning method is designed for semi-trailers on straight-road alignments. Firstly, we employ a fuzzy inference system to process information about surrounding traffic, make lane-changing decisions, and determine the starting point. Secondly, the lane-changing path is generated using a B-spline curve. Subsequently, we apply a particle swarm optimization algorithm to enhance the B-spline curve. Thirdly, we utilize a Transformer model to analyze the nonlinear relationships among information about surrounding traffic, vehicle information, and the roll stability of the intelligent semi-trailer. We establish the roll stability boundary for the vehicle. Finally, we design a multi-objective cost function to select the optimal path. The simulation results demonstrate that the proposed method dynamically adapts the planned path to variations in driving parameters, ensuring trackability while reducing the steering angle, lateral acceleration, and yaw rate. This approach meets the roll stability requirements of intelligent semi-trailers, significantly enhances their stability during lane changing, and provides robust support for safe and efficient operation. Full article