Comparison of biaxial mechanical and microstructural properties between human femoral arteries and surrogate models for stent development.

Tailored flow condensation of low surface tension fluids via additively manufactured gradient wick structures

A novel high-gain Genus Hologram Antenna (GHA) based on surface impedance modulation using a periodic array of hexagonal patches is proposed for MIMO applications. The antenna features a simple, low-profile, low-cost structure that eliminates the need for complex feeding networks while achieving frequency-dependent beam scanning, multi-beam generation, and high radiation efficiency. The proposed GHA demonstrates wide-angle beam scanning from 30° to 64° over the frequency band of 13-17GHz, with a peak gain of 20.6 dBi and radiation efficiency of 87%. By controlling the lattice periodicity of the hexagonal patches, dual-beam radiation at (30°, 40°) and (60°, - 60°), as well as four-beam operation at (120°, 60°, - 60°, - 120°) with a gain of 15.2 dBi at 16GHz, are successfully realized. For MIMO applications, two GHA elements are integrated with an extremely compact edge-to-edge spacing of only 4.7mm (0.25λ₀ at 16GHz). By strategically inserting parasitic elements between the radiating units, the mutual coupling is significantly reduced from - 10 dB to below - 20 dB across the entire operating band, while maintaining excellent diversity performance (ECC < 0.003 and DG ≈ 10). Additionally, the conformal performance of the GHA is investigated on curved surfaces in both transverse and longitudinal directions, confirming its suitability for integration on platforms such as missiles, vehicles, aircraft, and trains. The proposed Genus Hologram Antenna offers a compelling combination of high gain, wide beam-scanning range, multi-beam capability, excellent MIMO isolation, and conformality, making it a strong candidate for modern 5G/6G wireless systems and compact high-performance platforms.

Abstract With the advancement of tunnel and underground engineering, the geological environment has grown increasingly intricate, posing significant challenges to existing technologies. In particular, when tunnels traverse high geothermal areas, elevated temperatures within the tunnel not only compromise construction quality but also pose health risks to workers. Duct ventilation stands out as a widely employed mitigation measure. However, currently the temperature field variation induced by duct ventilation in construction tunnels can only be analysed through numerical simulations, requiring case-by-case modelling and computation, and the analytical assessment of the cooling efficacy of duct ventilation predominantly relies on steady-state analyses of operational tunnels, neglecting the consideration of the longitudinally differentiated distribution of heat transfer efficiency and the dynamic changes in the temperature field during tunnel construction. Motivated by these shortcomings, this study introduces a novel semi-analytical model for construction duct ventilation in high-thermal tunnels, utilizing the Green's function method (GFM) and Dirac's function. The model incorporates a trough equivalent ring heat source at the air-rock interface and a non-uniform convective heat transfer coefficient (CHTC) distributed along the longitudinal direction via a Gaussian function. This approach enables the determination of the unsteady temperature field within a dead-end tunnel, facilitating a comprehensive evaluation of the cooling effect. The findings reveal substantial variations in the temperature field of the surrounding rock along the longitudinal direction in a short timeframe, underscoring the significance of dynamic cooling assessments. The derived temperature distribution aligns well with numerical simulations and field-test results in high-geothermal tunnels. Further parametric analysis emphasizes the pronounced boundary effect of ventilation cooling, leading to suggested optimal ventilation rates tailored to different rock masses. This research provides valuable insights for optimizing tunnel construction in high-thermal environments.

ABSTRACT Depositional models for straits have predominantly focused on symmetric systems in both the longitudinal (along‐strait) and transverse (across‐strait) directions. This framework overlooks straits characterised by significant asymmetry, specifically those displaying profound imbalances in both directions regarding topography, hydrodynamics and sediment supply. Bohai Strait, connecting the Bohai and Yellow Seas, serves as an important example to investigate this topic. Transversely, it features a deep, tide‐dominated northern passageway that contains little mobile sediment operating in parallel with a shallow, wind‐driven southern margin receiving the immense fine‐grained load of the Yellow River. Longitudinally, the strait exhibits an asymmetry, characterised by a larger flood‐tidal delta that contrasts with a much smaller ebb‐tidal delta. The asymmetric products of the Bohai Strait result primarily from a three‐stage evolution throughout the late Pleistocene and Holocene. The incipient strait (~11.6 to 10.3 ka cal BP) was characterised by the discharge of the Yellow River into the central Bohai Sea, which deposited the paleo‐Shandong Mud Wedge. A critical reorganisation probably started at ~10.3 ka cal BP, driven by two factors: the widening of the strait and the cutoff of mud supply due to the southward avulsion of the Yellow River. This event triggered a spatial contrast, causing a widespread depositional hiatus in the south while initiating the tide‐dominated channel with its sandy flood‐tidal delta in the north. After ~6.5 ka cal BP, the return of the Yellow River to Bohai Sea amplified this spatial divergence between the deeply scoured northern tide‐dominated system and the shallow southern supply‐dominated system. Overall, the northern half of the Strait experiences net input of locally eroded sand to the Bohai Sea (i.e. it is flood‐tide dominated), whereas the southern half exports mud to the Yellow Sea. The Bohai Strait highlights that longitudinal and transverse asymmetries in sedimentary processes and products require a broader framework beyond the simplified tidal‐strait models.

ABSTRACT Despite substantial cross-sectional evidence linking gratitude to socially oriented behaviors, the longitudinal directionality of these associations remains unclear. Grounded in the Catalyst Model of Change (CMC), this study examined reciprocal longitudinal associations between gratitude and five socially oriented behaviors: social support – seeking behaviors, prosocial behaviors, relationship initiation and enhancement behaviors, participation in mastery-oriented social activities, and reductions in maladaptive interpersonal behaviors. 413 U.S. participants were assessed twice over one year. Cross-lagged panel models tested bidirectional associations while controlling for autoregressive effects and within-time correlations. Gratitude predicted subsequent engagement in certain socially oriented behaviors, whereas reverse paths were nonsignificant. Gratitude at Time 1 predicted social support seeking and relationship initiation and enhancement at Time 2 (with large effects) but not prosocial or maladaptive interpersonal behavior or mastery-oriented social activities. Consistent with the CMC, findings highlight gratitude’s role in promoting engagement in social behaviors. Limitations and implications are discussed.

Abstract Affected by strong ground motions, the severe damages on main tunnel in tunnel portal zone were observed in several seismic events. To reveal the dynamic response characteristics of main tunnel in high-intensity seismic zone, a fabricated three-dimension numerical model considering the end wall tunnel portal, open tunnel, and main tunnel as an entire system was established in this paper to investigate the aseismic characteristics under transverse excitation and three-component earthquake excitation based on a tunnel engineering in high-intensity earthquake zone. Subsequently, the aseismic ability of tunnel was estimated. The dynamic features of main tunnel along longitudinal direction and the corresponding damage status were ascertained and then aseismic fortification length of the main tunnel in the tunnel entrance zone was suggested furtherly. Finally, the shock absorbing effect of foam concrete, its effects in mitigation was investigated. The results showed that the dynamic response of the tunnel in the entrance zone gradually decayed to a relatively stable status with the increasing of the distance from the tunnel portal. Compared with the tunnel dynamic response under transverse excitation, it maintains a significant effect in vertical component under three-component earthquakes. An optimal mitigation layer thickness for a special tunnel engineering will be presented according to the mitigation effect of main tunnel. When the tunnel site area is located at high-intensity earthquake area and the near-field seismic effect is obvious. The research result can provide reference for seismic performance evaluation and seismic isolation technology of portal part of mountain tunnel in the high-intensity earthquake areas.

REBCO coated conductor has great potential to be used in ultra-high field magnets. Commercial REBCO tapes are strong in the longitudinal direction but prone to delamination by tensile stress in the thickness direction. For high field magnet applications, it is crucial to characterize delamination strength of REBCO conductor and better manage the electromagnetic stress. In this work, the electromagnetic stress in high magnetic fields by screening current is used to study the delamination behavior of commercial REBCO tapes. Screening currents are induced in REBCO by either ramping field or rotating sample in magnetic fields up to 35 T. The results of delamination strength are presented. The prospect of using this method for quality assurance in large magnet projects is discussed.

Shallow-etched tilted nano-gratings and bridge waveguide assisted silicon polarizing beam splitter

BackgroundAdjuvant radiotherapy can be considered the standard of care for patients diagnosed with primary breast cancer who have undergone breast-conserving surgery. Left breast cancer receiving adjuvant deep inspiration breath hold (DIBH) were evaluated. A technique for monitoring patient position during DIBH is the surface guided radiation therapy (SGRT) as Vision AlignRT. The aim of this study was to estimate setup accuracy with AlignRT compared to AlignRT Advance in a cohort of patients undergoing DIBH treatment of breast cancer.Materials and methodsOne hundred and fifty‐four patients were studied. Patient positioning was informed using SGRT and verified by cone beam computed tomography (CBCT). Patients were divided into groups (G) based on treatment volume and version of Vision AlignRT. Comparison was performed by two tailed t-test. Data were deemed as statistically significant if p < 0.001.ResultsThe setup error for all patients treated with DIBH radiotherapy (RT) was calculated by CBCT. For left breast treatments, the interfractional displacement in the longitudinal and vertical directions was significantly (p < 0.001) reduced in patients positioned with the advanced version. For breast and supraclavicular lymph node chain and/or internal mammary chain treatments, interfractional displacement in the lateral and vertical directions was significantly (p < 0.001) reduced when the advanced version was used, while for longitudinal displacement the reduction was not significant.ConclusionsPositioning with AlignRT Advance is more accurate for either left breast only or left breast and supraclavicular lymph node chain and/or internal mammary chain treatments.

Abstract Numerous investigations demonstrated the orthotropic characteristics of the femur, either in the proximal part or by considering it two-dimensional (2D). Many studies that have investigated orthotropic bone adaptation of the entire three-dimensional (3D) femur under cyclic loading induced during different physiological activities. To accurately capture adaptive behavior, one crucial factor is the way we assign orthotropic material orientation. This study investigates adaptive orthotropic bone remodeling using an FE diffusion-based approach for a 3D full-scale human femur geometry under different physiological activities. The comparison with the isotropic model is also carried out to observe the variations in results. To accomplish this, an FE model of the full right femur was developed to simulate bone adaptation using orthotropic and isotropic constitutive modelling. A FE method based on diffusion equations was presented to evaluate the complex continuum field of orthotropic orientations. Bone density evolution was predicted using a diffusion-based continuum remodeling approach. Results unveil an anatomically consistent local field of orthotropic orientations in longitudinal, circumferential, and radial directions. In orthotropic models, the density distribution was found to be substantially higher throughout the posterior part of the femoral diaphysis. Bone resorption was observed in the condyle region, the latero-superior greater trochanter region, and the superior region of the femoral head. A notable difference for the isotropic models is that the entire femur exhibits a uniform remodeling response, particularly in the diaphyseal. Overall, the orthotropic bone adaptation provides more detailed anatomical information regarding region-specific adaptation.

Abstract The rigidity of the additively manufactured objects can be tailored by manipulating the infill lattice type and density. In this research, an island-type novel infill structure termed the Hexagonal-Zigzag pattern is introduced, and its mechanical performance is investigated. In this pattern, the zigzag raster reflects the repeating hexagonal-shaped cell constituting the parallel-oriented islands, and a 90 deg rotation of the pattern in each layer distributes the island span along both transverse and longitudinal directions of the printing contour. A mathematical model is established to illustrate the effect of the infill parameters on hexagon unit cell size and relative infill density. The compression test is executed on some rectangular test samples to characterize the nature of this pattern and explore its performance over other existing infill patterns: Honeycomb, Zigzag, and Triangle. The test result reveals that the compressive strength and elastic modulus of the proposed infill pattern are comparable with those of the Honeycomb infill pattern. Furthermore, the highest plateau stress and absorbed energy density demonstrate the performance of the proposed infill pattern. In addition, the experiment is extended to investigate the mechanical behavior of the proposed infill pattern with various hexagon unit cell sizes. The experimental results reveal the related pros and cons, such as increasing compressive strength and energy density with the enlargement of unit cell size, exhibiting its efficiency, whereas the decreasing elastic modulus and early densification represent the weakness.

Piezoelectric actuators are core components in precision motion control due to their unique electromechanical coupling properties. This paper establishes a dynamic model for a partially laminated piezoelectric-metal-piezoelectric beam actuator based on the Euler-Bernoulli beam theory. The model comprises symmetrically bonded piezoelectric layers on both sides of a central metal substrate, with the piezoelectric material partially distributed along the beam length. The structure is analyzed segment-wise along the beam's longitudinal length direction. By applying continuity conditions at the interfaces of varying cross-sections and leveraging the structural symmetry, analytical solutions for both the natural frequency and output displacement are derived. The analytical predictions are validated against finite-element results, and experiments also verify the accuracy of the analytical solution of the analytical voltage-displacement response. In addition, the effects of key geometric parameters on the dynamic performance are systematically investigated. The proposed model provides theoretical guidance for tuning the resonance characteristics and drive displacement design of the PMP actuators.

This study constructs an integrated obstacle avoidance control strategy that can account for both lateral and longitudinal dynamic obstacles, enabling vehicles to quickly and stably evade obstacles in even emergency scenarios, thereby preventing accidents in complex road environments. Firstly, based on the safety distance model, a risk area dynamic partition method that considers both lateral and longitudinal directions is established. Subsequently, within the Frenet coordinate system, quintic polynomial candidate paths are generated based on the vehicle’s acceleration, speed, and position before and after lane-changing, and the optimal path is determined with consideration of driving safety and comfort, as well as the constraints associated with it. Finally, utilizing a two-degree-of-freedom vehicle dynamics model and a lateral tracking error model, a lateral tracking controller based on Linear Quadratic Regulator (LQR) and a longitudinal tracking controller based on double Proportional-Integral-Derivative (PID) approach are designed. The results of hardware-in-the-loop experiments demonstrate that, compared to the LQR algorithm, the proposed strategy more effectively ensures the stability and obstacle avoidance capability of the vehicle during operation. Furthermore, data collected under various scenarios indicate that the proposed strategy meets the requirements for tracking performance and driving comfort while successfully ensuring obstacle avoidance. Overall, the proposed method satisfies the criteria for safety, comfort, and stability in vehicle obstacle avoidance within complex environments.

Glass fiber reinforced polymer (GFRP) composites produced by pultrusion are increasingly used in structural applications due to their advantages such as corrosion resistance, high strength-to-weight ratio, and lightness. However, the extensive use of fibers in the longitudinal direction causes imbalance in the cross-section, leading to web crippling behavior in profiles subjected to transverse vertical forces. In this study, the influence of temperature and hole diameter on the web crippling performance of pultruded GFRP U-section profiles was investigated experimentally and analytically. The specimens were perforated with circular holes with diameters of 32-50-70 mm (diameter/Height ratio d/H = 0.23-0.36-0.50) at the web center and exposed to high temperatures of 200-250-300 °C, respectively, along with room temperature. The experiments were conducted under ITF (interior-two-flange) and ETF (end-two-flange) loading conditions. According to the results obtained, ITF configurations exhibited approximately twice the load-carrying capacity compared to ETF configurations. Due to the effect of high temperature, the web-crushing capacity showed a significant decrease of up to 44% on average in all samples when the temperature was increased from 24 °C to 300 °C. Increasing the hole diameter (and consequently the d/H ratio) led to a gradual decrease in capacity ranging from 15.7% to 56.2%; in particular, it was demonstrated that the ETF loading configuration is more sensitive to the hole than the ITF. As a result of the study, an empirical equation considering the effects of temperature and hole size was proposed, and the model's predictions were compared with experimental results. Although the model successfully captured the general trend, the average absolute error rate in the predictions ranged between 12% and 14%, indicating improvement but not achieving ideal prediction accuracy.

The present study examined the longitudinal associations and directionality of effects between self-concept and eating disorder symptoms in late childhood and early adolescence. A total of 380 participants (Time 1: 52.2% female; M age = 9.97 years, SD = 0.84, range = 8–12 years) completed self-report questionnaires annually for 3 years. Cross-lagged panel models were used to examine the associations over time between global and domain-specific self-concept (i.e., physical appearance, scholastic competence, athletic competence, social acceptance and behavioral conduct) and eating disorder symptoms. The findings revealed that lower global self-concept and appearance-related self-concept predicted higher eating disorder symptoms over time, and vice versa. Eating disorder symptoms also negatively predicted scholastic competence and behavioral conduct over time. These results underscore the developmental interplay between self-concept and eating disorder symptoms, highlighting the importance of early self-concept interventions to prevent eating disorder symptomatology in children transitioning to adolescence.

In isolated animal muscles, contraction intensity and tissue stiffness have been shown to be related to gearing. However, these relationships remain poorly understood in humans. This study aimed to clarify how contraction intensity and velocity impact gearing and their relationship with tissue properties in humans. Fifty-two healthy young adults participated in this study. We measured the shear elastic modulus of the medial gastrocnemius muscle, its aponeurosis, and the Achilles tendon, as well as muscle echo intensity. The shear elastic modulus of the aponeurosis was used for analysis as the ratio of transverse to longitudinal directions. Belly segment gear was quantified using ultrasound images of the medial gastrocnemius during isokinetic and isometric plantarflexion. During isometric contraction, belly segment gear under 60% MVC (1.054 ± 0.029) was significantly greater than that under 20% MVC (1.029 ± 0.044). In contrast, during isokinetic contraction, no significant difference between belly segment gear under 100°/s (1.053 ± 0.024) and that under 20°/s (1.056 ± 0.021) was observed. During lower-intensity, higher-velocity isokinetic contractions, greater belly segment gear was associated with a higher transverse to longitudinal stiffness ratio of the superficial aponeurosis (β = 0.274, p = 0.038), lower tendon stiffness (β=-0.312, p = 0.021), and lower echo intensity (β=-0.308, p = 0.021). Furthermore, mediation analysis revealed that the effect of aponeurosis stiffness on torque through belly segment gear was significant (indirect effect = 4.35; 95% confidence interval, 0.11-10.09). Belly segment gear was associated with contraction intensity and connective tissue properties.

Bridge construction needs innovative sustainable solutions for enviro-economic improvement worldwide. The study presents a parametric finite element static and dynamic analyses incorporating bamboo into the core of the bridge’s deck, and it is surrounded by a carbon fibre-reinforced polymer (CFRP). The study examines variations in the thickness of the individual layers while maintaining almost constant overall volume, along with changes in the ply angle (0°, 30°, 60°, 90°) and skew angle (0°, 15°, 30°, 45°, 60°) under Indian Road Congress (IRC) Class A loading. The modelling and analysis are carried out using ANSYS Workbench to assess the static and dynamic (free vibration) responses, namely stress, deflection, normal stresses in both longitudinal and transverse directions, and natural frequencies, which is followed by validation of the present approach against established literature. Among all configurations, a ply angle of 60° consistently produces more favourable results (lesser stress and deflection values) regardless of core thickness or skew angle. The maximum equivalent stress, maximum deflection, and maximum normal stress along the transverse direction of laminated composite bridge decking typically decrease as the skew angle increases. By producing fewer values for these parameters across a range of skew angles and core thicknesses, a ply angle of 60° consistently exhibits the best performance. The 60° ply angle often retains comparatively superior performance, even if the longitudinal stress exhibits more complicated behaviour. The majority of modal frequencies peak at about 60° across all skew angles and wood-to-CFRP ratios, suggesting that this is the best orientation for maximising overall strength. This consistent pattern across all skew angles suggests that the dynamic response is consistent regardless of the skew angle. Skewness improves stress distribution, further reducing critical responses. These findings suggest an optimal ply configuration that can significantly enhance the structural efficiency of sustainable sandwich deck systems.

The article presents a theoretical analysis of the anisotropic thermal conductivity of multilayer hexagonal boron nitride (h-BN) nanoscrolls as promising fillers for thermal interfaces in electronic devices. Traditional thermally conductive composite materials, while possessing high thermal conductivity, are prone to agglomeration within the polymer matrix; their chemical inertness hinders the formation of strong bonds with the polymer, and their high electrical conductivity significantly limits their application in electronics. The h-BN-based material combines high thermal conductivity, excellent electrical insulation properties, and high processability for integration into electronic components. An analytical model is proposed to predict the thermal conductivity values of multilayer h-BN nanoscrolls in both the longitudinal and transverse directions. The analytical model for the anisotropic thermal conductivity of multilayer nanoscrolls (scrolled 2D nanoplates) is developed based on the generalized conductivity theory. Key scientific enhancements to existing models include the capability to increase the number of calculable layers and the dimensions of the nanoscrolls. To more accurately describe size effects, an interlayer scattering parameter is introduced for the first time in such a multilayer structure to correct the effective phonon mean free path within the material. Mathematical dependences of the thermal conductivity of multilayer h-BN nanoscrolls on the number of layers were obtained for the directions longitudinal and transverse to the nanoscroll axis. It is shown that as the number of layers increases, the longitudinal thermal conductivity (along the nanoscroll axis) decreases. The transverse thermal conductivity (perpendicular to the nanoscroll axis) is significantly higher than that of their carbon-based counterparts. Due to the absence of quantitative data (both experimental and numerical) for multilayer boron nitride nanoscrolls in available scientific literature, validation of the simulation results was performed on a similar system reported in open sources — a three-layer carbon nanoscroll. The obtained predictive results allow for assessing the influence of the layer count on the thermal conductivity of h-BN nanoscrolls and for synthesizing multilayer nanoscroll structures with a predetermined thermal conductivity value. It is demonstrated that multilayer h-BN nanoscrolls represent a promising alternative to carbon nanotubes in electronics for applications where it is critically important to eliminate “thermal bottlenecks” and ensure high inter-component electrical insulation.

Rubber–textile conveyor belts with polyester–polyamide (EP) carcasses are widely used in bulk material handling, where their mechanical performance significantly affects their reliability, safety and service life. Due to the anisotropic structure of the textile reinforcement, the deformation of EP belts is strongly dependent on the loading direction. This study investigates the deformation rate behavior of rubber–textile conveyor belts under uniaxial tensile loading, with an emphasis on the differences between the longitudinal (warp) and transverse (weft) directions. The experimental results show that the strain rate is controlled by different deformation mechanisms of the textile components, which leads to significantly different deformation kinetics under warp and weft loading. The findings provide new insights into the time-dependent tensile behavior of EP belts and support the optimization of the textile carcass design for better durability and sustainability under severe operating conditions.