Offset Distance Research Articles

The Effect of Preloaded Compressive Stress and Curvature of Defect on Blast-Induced Fracture Behavior by Caustic and Numerical Models

In this study, the effects of preloaded uniaxial compressive stress and defect (prefabricated by laser cutting) curvature on blast-induced cracks and stress wave propagation were investigated in polymethyl methacrylate (PMMA) specimens using caustics theory. Based on the mathematical relationship between stress and optics, the fracture behavior (the propagation path, dynamic stress intensity factors (DSIFs), propagation velocity, initiation angle of the main crack, and damage degree between the defect and the blasthole) was calculated and analyzed quantitatively. The results show that the preloaded stress could mainly restrain the main crack propagation in the horizontal direction and reduce the initiation angle and damage degree at the defects. Meanwhile, the crack initiation position of the positive curvature defect was not at the end of the defect. In addition, the curvature of the defect significantly affected the blast-induced fracture compared to preloaded stresses. Comparing the main crack with other curvature defects, the DSIFs, velocity, crack arrest time, crack length, and horizontal offset distance of the main crack with negative curvature defect were the largest. The variation in the full stress field in the specimen under blasting and preloaded stress was simulated by a numerical model. The results show that the curvature of the defect has a significant effect on tensile waves at the end of defects, and the tensile stress from high to low was C-25, C0, and C25, in that order.

Orientation of Corannulenes inside Carbon Nanotubes

AbstractCorannulenes have received much interest due to their electronic properties, which differ between the convex and concave surfaces of the molecule. The ability to control the shapes of corannulenes to optimize charge distribution is therefore important for the development of seminconductors and electronic devices. In this paper, the interactions of corannulenes are modeled inside carbon nanotubes of various sizes using the Lennard–Jones potential and a continuum approach. The major contribution of this work is the analytical expressions for the interaction energy, which are obtained as a function of the nanotube's radius, the offset distance of corannulene from the tube's axis and the orientation of corannulene. Minimizing this energy, the range of nanotube's radii that allow the corannulene to adopt lying, tilting and standing configurations both on‐ and off‐axis of the nanotubes is determined. These results are supported by the density functional theory calculations and agree with previously published work using molecular dynamics simulations for corannulenes located on the nanotube's axis.

Ionic transport through a bilayer nanoporous graphene with cationic and anionic functionalization.

Understanding the ionic transport through multilayer nanoporous graphene (NPG) holds great promise for the design of novel nanofluidic devices. Bilayer NPG with different structures, such as nanopore offset and interlayer space, should be the most simple but representative multilayer NPG. In this work, we use molecular dynamics simulations to systematically investigate the ionic transport through a functionalized bilayer NPG, focusing on the effect of pore functionalization, offset, applied pressure and interlayer distance. For a small interlayer space, the fluxes of water and ions exhibit a sudden reduction to zero with the increase in offset that indicates an excellent on-off gate, which can be deciphered by the increasing potential of mean force barriers. With the increase in pressure, the fluxes increase almost linearly for small offsets while always maintain zero for large offsets. Finally, with the increase in interlayer distance, the fluxes increase drastically, resulting in the reduction in ion rejection. Notably, for a specific interlayer distance with monolayer water structure, the ion rejection maintains high levels (almost 100% for coions) with considerable water flux, which could be the best choice for desalination purpose. The dynamics of water and ions also exhibit an obvious bifurcation for cationic and anionic functionalization. Our work comprehensively addresses the ionic transport through a bilayer NPG and provides a route toward the design of novel desalination devices.

Experimental investigations on flow characteristics of impingement/swirl cooling structures inside a blade leading edge

Experimental investigations were conducted to study the flow characteristics of impingement/swirl cooling structures inside a turbine-blade leading edge (LE) using particle image velocimetry. The Reynolds number (Re) was maintained at either 10 000 or 20 000. The effects of Re and the ratio of the impingement-cooling (IC) hole offset distance to the IC hole diameter (e/d) on the flow phenomena and the characteristics of the impingement/swirl cooling structures inside the blade LE were analyzed. The effects of the coolant-outflow mode were also taken into consideration. The results show that when e/d = 0, the diffusion flow of the impingement jet moves more to the side of the LE with a larger rounded corner, and this phenomenon is particularly obvious at Re = 20 000. Regardless of the e/d value, both the impingement-jet velocity and vorticity increase significantly at a higher Re value. The velocity of the impingement jet reaching the internal impingement target surface of the LE decreases significantly as e/d is changed from 1.5 to −1.5 with Re = 20 000. Generally speaking, regardless of the e/d value, the impingement jet can form a swirling vortex on the side with the larger rounded corner. Under the conditions of Re = 20 000 and e/d = 1.5, regardless of the coolant-outflow mode, the flow velocity of the impingement jet decreases monotonically along the flow direction, and this is more obvious inside the LE model without film-cooling holes.

Application and Research on Improved Adaptive Monte Carlo Localization Algorithm for Automatic Guided Vehicle Fusion with QR Code Navigation

SLAM (simultaneous localization and mapping) technology incorporating QR code navigation has been widely used in the mobile robotics industry. However, the particle kidnapping problem, positioning accuracy, and navigation time are still urgent issues to be solved. In this paper, a SLAM fused QR code navigation method is proposed and an improved adaptive Monte Carlo positioning algorithm is used to fuse the QR code information. Firstly, the generation and resampling methods of initialized particle swarms are improved to improve the robustness and weights of the swarms and to avoid the kidnapping problem. Secondly, the Gmapping scan data and the data generated by the improved AMCL algorithm are fused using the extended Kalman filter to improve the accuracy and stability of the state estimation. Finally, in terms of the positioning system, Gmapping is used to obtain QR code data as marker positions on static maps, and the improved adaptive Monte Carlo localization particle positioning algorithm is matched with a library of QR code templates, which corrects for offset distances and achieves precise point-to-point positioning under grey-valued raster maps. The experimental results show that the particles encountered with kidnapping can be quickly adjusted in position, with a 68.73% improvement in adjustment time, 64.27% improvement in navigation and positioning accuracy, and 42.81% reduction in positioning time.

Using aircraft tracking data to estimate the geographic scope of noise impacts from low-level overflights above parks and protected areas

Sightseeing air tours have proven to be a challenging management issue for many tourist destinations around the world, especially at locations meant to protect natural and cultural resources and wilderness character. Two of the primary challenges with managing air tours are a lack of information about their travel patterns and how such patterns result in a measurable noise impact to listeners. Recent studies have highlighted the usefulness of newer technology for tracking aircraft travel patterns, particularly over national parks. In this synthesis, we pair aircraft tracks with acoustic data using a quantitative observer-based audibility modelling software toolkit. The findings delimit the long-term geographic scope of audibility for specific aircraft noise sources above landscapes of Hawai'i Volcanoes and Denali National Parks, U.S. and identify practical, 3-dimensional offset distances that can be used to reduce the functional effects of air tour noise in terms of sound level.

Design and optimization of the magnetic field-driven spherical gripper with adjustable stiffness

This paper presents a new gripping technique that merges the variable stiffness characteristics of conventional magnet-controlled and negative-pressure spherical grippers to produce a spherical gripper capable of securely grasping large and structurally diverse objects. The proposed method incorporates the smart rheological material from magnet-controlled grippers with the particle-jamming smart structure used in negative-pressure grippers. The gripper comprises a magnetic control device and a spherical variable stiffness body. Simulation analysis was used to optimize its structure and enhance the efficiency ratio of the magnetic control device. The flexible variable stiffness body was initially designed to be cylindrical to increase interlocking with objects. Experiments were conducted to evaluate the gripping efficiency and adaptability of the magnetron spherical gripper, which were designed to simulate real-world application requirements. These results suggest that the magnetically controlled spherical gripper can achieve a gripping efficiency of approximately five and securely grasp objects with a relative bladder diameter ranging from 20 % to 130 %. Furthermore, it can stably grip objects up to an offset distance of 15 mm without requiring sensor assistance. The enhanced magnetic field-powered spherical gripper exhibits superior adaptability and efficiency in gripping compared to its counterpart. In addition, it boasts robust resistance against environmental interference.

Control of corner arc radius in wire electrochemical micromachining

Wire electrochemical micromachining (WECMM) technology is commonly used to process micro parts. Some thick parts contain many sharp structures, and have high machining accuracy requirements for the arc radius at the corner, such as jet sheet, micro gear, etc. However, when machining thick workpiece, it is easy to form a large arc radius at the corner due to stray corrosion and difficult discharge of electrolytic products. In order to solve this problem, this paper proposes a corner path optimization method, which reduces the arc radius of the sharp structure by adjusting the processing path of the wire electrode, thereby improving the machining accuracy of the sharp structures. The model of the relationship between the inclination of the machining path and the angle of the sharp structure is established. The inclination and offset distance of the processing path are obtained through theoretical calculation, and further optimized through experiments to avoid overcut or undercut at the corner. In the experiment, tungsten wires with different diameters were used as wire electrodes to process acute angle, right angle and obtuse angle structures on 510 μm thick 9Cr18Mo stainless steel. The influence of wire electrode processing path on the corner arc radius of different angle sharp structures was explored. The experimental results show that compared with the original path, the arc radius of the sharp structure could be reduced from tens of microns to <5 μm by using the optimized processing path.

Coupling coefficient calculation and optimization of positive rectangular series coils in wireless power transfer systems

In wireless power transfer (WPT) systems using magnetic coupling resonance, when there is a registration deviation between the transmitting and receiving coils, there will be significant fluctuations in the coupling coefficient, output power, and transmission efficiency, which will seriously affect the stability of the WPT system. The coupling coefficient is related to the length and width of the rectangular coil, number of turns, mutual geometric position, and space magnetic medium, making it difficult to maintain a constant value when the coil is offset. A single-emitter two-receiver positive-series rectangular coils structure and a method of calculating the structure are proposed. Then an optimization method for mutual inductance was proposed, and the structural parameters that met the design requirements were obtained using the proposed optimization method. The calculation formula for coupling coefficient was verified through simulation and experiments. The results showed that when the offset distance of the receiving coil along the Y-axis (driving direction) and X-axis reaches half of the length of the transmitting coil and 10 cm, the coupling coefficient, transmission efficiency, and output power remain almost unchanged.

Dynamic analysis of deep groove ball bearing with localized defects and misalignment

BackgroundOuter ring localized defects and inner ring misalignment are very common failures in bearings, and they are likely to exist at the same time and have complex impacts on bearing performance, especially when the defect is both offset and bias. Currently, there is a lack of a deep groove ball bearing model that can reasonably simulate this situation. MethodsIn this paper, a new time-dependent displacement excitation model based on piecewise function is proposed to analyze the process of ball passing through both offset and bias defects considering inner ring misalignment, and a 5-degree-of-freedom dynamic model is solved to obtain the vibration response. ResultsThe results show that the offset distance and bias angle can significantly change the excitation durations of entering and leaving the defect, further affecting the acceleration impact. In addition, inner ring misalignment can increase or decrease the bearing acceleration root mean square, depending on the direction of misalignment, and these effects are also related to the misalignment magnitude and the defect location. DiscussionThis study presents a feasible solution to model defective bearings with misalignment, and provides a theoretical basis for bearing fault diagnosis and performance prediction.

An adaptive feedback regulation method of wireless power transfer systems for compensating battery‐based source's fluctuations

SummaryThis article proposes an adaptive feedback regulation method for wireless power transfer (WPT) systems, which can be applied to solve the problem of the drop in input voltage from the emergency power supply such as a battery‐based source. The whole WPT system transfers power mainly through the mutual inductance between the transmitter and receiver coils. The compensation coils are accessed to form the power feedback side, which can achieve constant voltage output by adjusting the duty cycle of the DC/DC converter. Furthermore, the finite element simulation result analyzes the constant voltage output characteristics of the proposed topology under different load conditions. Finally, an 85 kHz prototype based on the proposed method is built and tested to verify the performance and effectiveness of the design. The proposed method achieves a constant 48 V output when the load varies from 60 to 120 Ω and the horizontal offset distance varies from 20 to 80 mm.

Observation on Curative Effect of Minimally Invasive Osteotomy Combined with Ilizarov Technique in the Treatment of Knee Osteoarthritis with Varus Deformity

This paper aims to analyze the clinical efficacy of minimally invasive osteotomy combined with Ilizarov technique in the treatment of knee osteoarthritis with varus deformity. 80 patients with knee osteoarthritis and varus deformity who were treated in our hospital from January 2022 to May 2023 were selected, all of whom were affected by one knee. They were randomly divided into groups, including the study group and the control group, each with 40 patients. Patients in the control group were treated with fibula-tibial osteotomy and internal fixation, and patients in the study group were treated with minimally invasive osteotomy combined with Ilizarov technique. The operation time of the patients in the study group was significantly longer than that of the control group (P &lt; 0.05). The intraoperative blood loss of the patients in the study group was significantly more than that of the control group (P &lt; 0.05). The hospitalization expenses of the patients in the study group were significantly more than those of the control group (P &lt; 0.05). The postoperative femorotibial angle and mechanical axis offset distance in the study group were significantly smaller than those in the control group (P &lt; 0.05). The postoperative New York Hospital for Special Surgery (HSS) scores of the study group were significantly higher than those of the control group (P &lt; 0.05). The postoperative visual analogue scale (VAS) score of the study group was significantly lower than that of the control group (P &lt; 0.05). The range of motion of the knee joint in the study group was significantly greater than that in the control group (P &lt; 0.05). The incidence of tendon injury, infection, and nerve injury in the study group (2.50%) was significantly lower than that in the control group (30.00%) (P &lt; 0.05). Minimally invasive osteotomy combined with Ilizarov technique can be applied in the treatment of knee osteoarthritis with varus deformity, although the operation time is longer, with more intraoperative blood loss and higher treatment cost, but it has no effect on the femorotibial angle and mechanical axis deviation of the patient. It can significantly improve the movement distance, knee joint function, and knee joint range of motion, and significantly reduce the postoperative pain of patients, reduce the incidence of complications, and thus has high clinical application value.

Seismic Evaluation of Metal-Strip Reinforced Soil Walls considering the Effect of Wall Configuration - A Shaking Table Study

ABSTRACT Shake table tests on two-tiered metal-strip MSE walls showed that the prevention of slip surface development in the lower half of the wall, improving seismic stability by increasing failure threshold acceleration, and mitigating acceleration amplification were the main advantages of using a two-tiered configuration in constructing MSE walls. This was also found that the use of an insufficient offset distance not only eliminated the advantage of the tiered configuration for reducing wall deformations, but also increased the wall crest displacement. Hence, 0.22 H was found to be as the minimum offset distance required when constructing MSE walls in a two-tiered configuration.

Fabrication of biomimetic anisotropic crescent-shaped microstructured surfaces by laser shock imprinting

Abstract The crescent-shaped microstructure bionic to the slip zone of the slippery zone of the carnivorous plant genus Nepenthes was fabricated on the surface of copper foil by laser shock imprinting (LSI). The microstructure of crescent-shaped grooves was initially fabricated on the surface of the micro-mold by etching, and then the microstructure was replicated on the surface of copper foil through plastic deformation under laser shock loading. Increasing the laser shock energy or the number of shocks can increase the degree of replication of the crescent-shaped microstructure, the height of the crescent-shaped microstructure, and the contact angle of water droplets on the surface. The wettability of the surface of the crescent microstructure is anisotropic and increases with an increase in offset distance. The anisotropy of the crescent-shaped microstructure causes the solid–liquid contact line in the direction of the bottom of the arc to become a long and approximately straight line. According to the rule that controlling LSI processing parameters can fabricate surfaces with different heights and wettability, a gradient wetting surface consisting of crescent-shaped microstructures was designed to achieve the directional spreading of droplets. By altering the distribution of crescent-shaped microstructures, a type-I flow channel with the ability to limit the spreading range of water droplets was fabricated.

Contributed Session II: In vivo imaging of immune cell activity in primate retina after photoreceptor ablation.

The non-human primate (NHP) is the gold standard animal model for preclinical development of gene and cell based therapies for vision restoration. However, the ocular immune response to these interventions remains poorly understood. We conducted a proof of concept study using offset aperture adaptive optics scanning light ophthalmoscopy (AOSLO) to visualize cellular-scale changes in the primate retina following photoreceptor (PR) ablation. Ultrafast 730nm laser exposure at 26.6 - 32.5 J/cm2 was used to create six lesions in four NHPs. Offset aperture images focused on retinal vascular layers were collected with an offset distance of ~10 Airy Disk Diameters from 15 minutes up to three hours after PR ablation. We observed putative immune cells in and around vessels supplying the lesioned areas. Consistent with previous findings in murine models, cells within vessels adhered to the inner wall, exhibited crawling behavior, and had a diameter ranging from ~9.3 - 11.5 µm. Additionally, we observed the emergence of cellular-scale structures above the PR layer that originated in the center of the lesion 15 minutes post-insult and gradually radiated outward. Vascular perfusion was maintained in these regions. Our data suggest that offset aperture imaging offers cellular-scale, label free, in vivo assessment of the retinal response to insult in NHPs and could be employed to advance our understanding of the ocular immune response provoked by disease and therapeutic interventions.

Switchable magnetic dipole assisted double QBICs in an asymmetry four-leaf clover-shaped Ge2Sb2Te5 metasurface

Dynamically tunable metasurface resonators with high Q factors and excellent sensing performance still lack research. This paper proposes a dual-band symmetry broken induced quasi bound state in the continuum (QBIC) sensor in the near-infrared region based on an asymmetric four-leaf clover-shaped Ge2Sb2Te5 (GST) metasurface. The high-quality transmission spectrum can be tuned by switching the GST crystalline state. Two QBIC magnetic dipole resonances are excited at the amorphous GST state, QBIC Ⅰ (intracavity MD mode) and QBIC Ⅱ (intercavity high-order MD mode). Based on theoretical simulation, the refractive index sensitivity of the QBIC Ⅱ mode (318.05 nm/RIU) is enhanced higher than twice of the QBIC Ⅰ mode (134.03 nm/RIU) owing to the unique electromagnetic field properties. The ultra-high Q factors generated by the two MD resonance modes are 1.1 × 105 (QBIC Ⅰ) and 1.71 × 105 (QBIC Ⅱ) respectively for a small perturbation of the air hole offset distance D = 5 nm. By discussing the effect of the main structure parameters and the analyte thickness on the sensitivity, the optimal parameters are determined. The two strong QBICs supported by the a-GST metasurface are stable when the air hole’s offset from the unit center is at different directions and distances, indicating a good tolerance to fabrication requirements. These results provide a competitive switchable dual-band QBIC metasurface sensor, providing a potential route for tunable metadevices for functional sensing and dynamic control over signals.

Object localization methodology in occluded agricultural environments through deep learning and active sensing

The predominance of branch and leaf shade in agricultural environments presents a barrier for accurate target recognition. Particularly for picking robots, precise localization of the picking object is essential. For this purpose, this paper proposes detection and localization methods based on deep learning and active sensing for harvesting robots in real-world environments with occlusion and varying lighting conditions. Using a deep learning network, the detection method firstly extracts the peduncle and fruit regions; the fruit region is then used to calculate the occlusion rate and the offset distance of the peduncle relative to the fruit. With such information, the robot arm adjusts the camera's field of view to perform multiple recognitions until the confidence is satisfied. Furthermore, to solve the picking problem caused by the peduncle's random tilting, this paper proposes a method to calculate the peduncle's tilt angle for controlling the end-effector to make the corresponding angle rotation. The robot arm and its end-effector are directed to complete the harvesting with the picking point location and tilt angle. In this study, data collection, detection and picking tests were implemented in the field, the results indicated that the method obtained an average successful picking rate of 90% after 300 trials, the error between the estimated occlusion ratio and the genuine value is 16% in average, and the active sensing method has improved the confidence score in occluded situations by over 50%. The proposed active methods have a 33% increase in precision and a 43% increase in efficiency compared to constant methods.

Deconvolutional Neural Network for Generating Spray Trajectory of Shoe Soles

The footwear industry is moving towards automation and intellectualization. To overcome the drawbacks of the high-cost and low-efficiency traditional manual shoe sole gluing process, automatic methods were utilized for generating spray trajectories. Currently, most of the reported automatic methods for generating spray trajectories mainly rely on the outer contour bias method. However, the glue is only applied to the area near the edge/contour of shoe soles and the fixed offset distance in the outer contour bias method cannot adapt to the immense amount of shoe styles with high precision and achieve applicability for irregular and unique sole designs. An intuitive yet logical approach to fulfill the requirements is to utilize the deconvolutional neural network for generating shoe sole spray trajectories. In this work, we treated the glue trajectory prediction as an image-to-image prediction and established a novel deconvolutional neural network to generate shoe sole spray trajectories. The as-proposed deconvolutional neural network for generating spray trajectory offered significant advantages over the existing bias-based methods, including: (1) based on the novel deconvolutional neural network, the proposed method for generating shoe sole spray trajectories exhibits greater applicability to irregular shoe soles, which improves the spray accuracy without compromising the spray efficiency; (2) we discard all the pooling layers, which only consist of convolutional and deconvolutional layers, to preserve more spatial information and achieve higher spray accuracy through end-to-end mapping from shoe sole images to shoe sole spray trajectories, resulting in an improved spray accuracy without sacrificing spray efficiency. The Dice similarity coefficient and Hausdorff distance were used as the evaluation metrics to assess the performance of our approach. Our proposed method showed an ultra-high accuracy and precision with a Dice similarity coefficient over 99.25% and a Hausdorff distance less than 1.2 mm, which are ~10% higher than the spray accuracy of other reported traditional methods. Our findings would bring significant improvements to the field of automatic shoe sole spray trajectory generation, which has the potential to promote the utilization of intelligent technologies in the footwear industry.

OrcaFlex predictions for a multi-float hinged WEC with nonlinear mooring systems: Elastic mooring force and dynamic motion

The mooring system can affect the motion and energy output characteristics of a WEC. This study investigated the effects of an SPM mooring system in a M4 6-float WEC. The scaled model of M4 was modelled via both Orcaflex and experimental approaches. Compared with experimental results, the accuracy of the numerical results was found to be sensitive to the simulation methods in OrcaFlex, and the filter method supplied a better agreement with experimental results in this study. Following the numerical method selection, another two mooring cables were introduced to compare different stiffness properties with respect to tension reduction. Compared with the other two mooring cables, cable 3 with negative bending has the lowest peak spectral density of tension in all wave conditions; however, its stiffness needs to be optimised to reduce the peak tension in some large wave conditions. According to this, the stiffness of cable 3 is initially adjusted, and the new cable 3 can reduce up to 30% offset distance and 50% peak tension. The results also found that the relative rotational motion of the M4 is not sensitive to stiffness properties, which means the future PTO selection could be independent of the mooring cable.

A novel method of human identification based on dental impression image

In large-scale natural disasters and special criminal cases, surface features of bodies, such as faces and fingerprints, are easily destroyed. Teeth possess strong high-temperature resistance, corrosion resistance, and high hardness, which can compensate for the shortcomings of the aforementioned situations. This paper proposes an identification method based on the aggregated features of multi-scale dental impression images. Firstly, a method exploiting the adaptive object detection method based on YOLOv8 is proposed to segment toothprints. Next, a novel geometric feature named calibrated offset distance is extracted, combined with the SIFT feature method, to extract multi-scale and multi-dimensional features from the global toothprint, local toothprints, and single-tooth prints. Finally, all features are aggregated to enhance the descriptive ability and robustness. Experimental results indicate that the method proposed in this paper demonstrates good identification performance.