Location Of Holes Research Articles

Tracking Charge Migration with Frequency-Matched Strobo-Spectroscopy.

We present frequency-matched strobo-spectroscopy (FMSS) of charge migration (CM) in bromobutadiyne, simulated with time-dependent density functional theory. CM + FMSS is a pump-probe scheme that uses a frequency-matched high harmonic generation (HHG)-driving laser as an independent probe step, following the creation of a localized hole on the bromine atom that induces CM dynamics. We show that the delay-dependent harmonic yield tracks the phase of the CM dynamics through its sensitivity to the amount of electron density on the bromine end of the molecule. FMSS takes advantage of the intrinsic attosecond time resolution of the HHG process in which different harmonics are emitted at different times and thus probe different locations of the electron hole. Finally, we show that the CM-induced modulation of the HHG signal is dominated by the recombination step of the HHG process, with a negligible contribution from the ionization step.

Influence of a cutting fluid on the surface integrity and fatigue strength of 42CrMo4 drilled parts.

This study investigates the influence of a cutting fluid during the drilling operation on the surface integrity and fatigue strength of 42CrMo4 hardened steel. The investigation includes characterizing surface topography, microstructure at different hole locations, and residual stresses. Fatigue tests were conducted, and the results were correlated with observations on surface integrity. The findings reveal that crack initiation occurs in a transition zone within the hole, where the cutting process evolves from pure cutting to a region with a strongly adhesive layer. The absence of cutting fluid leads to increased surface roughness and tensile residual stresses, resulting in a 28% reduction in fatigue strength.

How Many Supermassive Black Hole Binaries Are Detectable through Tracking Relative Motions by (Sub)millimeter Very Long Baseline Interferometry?

The (sub)millimeter wavelengths (86–690 GHz) very long baseline interferometry will provide ∼5–40 μas angular resolution, ∼10 mJy baseline sensitivity, and ∼1 μas yr−1 proper-motion precision, which can directly detect supermassive black hole binary (SMBHB) systems by imaging the two visible sources and tracking their relative motions. Such a way exhibits an advantage compared to indirect detect methods of observing periodic signals in motion and light curves, which are difficult to confirm from competing models. Moreover, tracking relative motion at (sub)millimeter wavelengths is more reliable, as there is a negligible offset between the emission region and the black hole center. In this way, it is unnecessary to correct the black hole location by a prior of jet morphology as it would be required at longer wavelengths. We extend the formalism developed in D’Orazio & Loeb (2018) to link the observations with the orbital evolution of SMBHBs from the ≲10 kpc dynamical friction stages to the ≲0.01 pc gravitational radiation stages, and estimate the detectable numbers of SMBHBs. By assuming 5% of active galactic nuclei holding SMBHBs, we find that the number of detectable SMBHBs with redshift z ≤ 0.5 and mass M ≤ 1011 M ⊙ is about 20. Such a detection relies heavily on proper-motion precision and sensitivity. Furthermore, we propose that the simultaneous multifrequency technique plays a key role in meeting the observational requirements.

A Novel 3-Dimensional Printed Nanoceramic Hybrid Resin Fixed Lingual Retainer: Characterization and Mechanical Tests.

Introduction: An innovative retention protocol was developed to create a new 3D-printed fixed retainer employing SprintRay OnX nanoceramic hybrid resin. The feasibility and usability of the retainer were subsequently evaluated. Methods: Identification and characterization of SprintRay OnX was done using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive X-ray (SEM-EDX), field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and flexural strength. Load-deflection and pull-out tests were conducted on the 3D-printed straight wires, with three distinct cross-sectional geometries: round (1 mm), oval (1 mm × 1.5 mm) and semielliptical (1 mm × 1.5 mm). Twisted G&H and coaxial Respond stainless steel multistrand retainers were used for comparison. In the load-deflection test, a three-point bending test (3PBT) was employed. For the pull-out test, the retainer wire was inserted into the composite, which was placed in a centrally located hole of an acrylic block; the retainer wire was subjected to a tensile force along its long axis. Results: Characteristic bands close to those of PMMA were observed in the FTIR spectra. SEM-EDX and XRD revealed a crystalline material with homogeneously distributed Yb element signals (19.4%). On FE-SEM micrographs, small clumps were displayed on smooth surfaces. The flexural strength and the flexural modulus were, respectively, 142.48 MPa and 7.842 GPa. All groups of 3D-printed wires exhibited significantly higher load-deflection levels than the multistrand wires (MSWs). Concerning pull-out forces, they fell in between twisted G&H (96 N) and coaxial Respond (48.09 N) retainer wires. The 3D-printed wires fractured cohesively without detachment from the adhesive, suggesting that the chemical bond was adequate for satisfactory wire integration, yet the wire's strength was compromised. Concerning the cross-sectional geometry, the load-deflection and the pull-out forces of 3D-printed oval and semielliptical wires were significantly higher than that of 3D-printed round wires, which was attributed to the larger cross-sections of the wires. Conclusion: Oval and semielliptical 3D-printed wires offered favorable features as lingual retainers.

Automated defect detection in precision forging ultrasonic images based on deep learning

Ultrasonic testing is a widely used non-destructive testing technique for precision forgings. However, assessing defects in ultrasonic B-scan images can be prone to errors, misses, and inefficiencies due to human judgment. To address these challenges, we propose a method based on deep learning to automate the evaluation of such images. We started by creating a dataset comprising 8000 images, each measuring 224 × 224 pixels. These images were cropped from ultrasonic B-scan images of 7 specimens, each featuring different sizes and locations of holes and crack defects. We then used state-of-the-art deep learning models to benchmark the dataset and identified YOLOv5s as the best-performing baseline model for our study. To address the challenges of deploying deep learning models and the issue of small defects being easily confused with the background in ultrasonic B-scan images, we made lightweight improvements to the deep learning model. Additionally, we enhanced the quality of data labels through data cleaning. Our experiments show that our method achieved a precision of 97.8%, a recall of 98.1%, mAP@0.5 of 99.0%, and mAP@.5:.95 of 67.6%, with a frames per second (FPS) of 74.5. Furthermore, the number of model parameters was reduced by 43.2%, while maintaining high detection accuracy. Overall, our proposed method offers a significant improvement over the original model, making it a more reliable and efficient tool for automated defect assessment in ultrasonic B-scan images.

Analytical optimization of open hole effects on the tensile properties of SS400 sheet specimens using an integrated FFD-CRITIC-DFA method

Structural components are generally composed of material discontinuities, including open holes, which are considered stress concentrators in engineering components. In view of this, assessing the influence of open holes on the tensile properties is crucial to determine the sensitivity and tensile strength of a particular material. Nevertheless, investigation of the impact of open holes on the tensile properties of SS400 steel sheets is very limited and yet to be explored. Therefore, this study was performed to optimize the effects of open holes on the tensile properties of SS400 sheet specimens based on a Full Factorial Design (FFD) experiment. Four input parameters that represent various hole configurations, which include the hole diameter, location of the hole, number of holes, and hole shape, were considered in this study to develop the experimental-based prediction models to optimize the output performance, namely yield strength, ultimate tensile strength, and ultimate elongation, commonly denoted as YS, UTS, and UE respectively. A total of 10 additional experimental trials were then utilized to verify the constructed models. In addition, the weight fractions for YS, UTS, and UE were identified using the Criteria Importance Through Inter-Criteria Correlation (CRITIC) method. Subsequently, the Desirability Function Analysis (DFA) is utilized to pinpoint the optimal parameter conditions for maximizing the tensile properties. Based on the results, all four parameters showed significant effects on the response variables, except the number of holes for UTS and hole location for UE. The diameter also recorded the highest contribution toward UTS and UE, followed by the hole shape. Regarding YS, hole diameter takes precedence, with the number of holes as the second most influential factor. Furthermore, the average absolute percent deviation for the prediction responses of 10 experimental cases were 1.06 %, 0.90 %, and 0.85 % for YS, UTS, and UE, respectively, confirming the validity of the constructed models. Meanwhile, the CRITIC method estimated the weight fractions for YS, UTS and UE from the experimental data, which were 0.3825, 0.2559, and 0.3616, respectively. The DFA-derived composite desirability, rated at 0.9820, suggests optimal conditions: a 1 mm hole diameter, centered hole location, three holes, and a hexagonal shape. The minimal deviations between predicted and experimental values affirm the robustness of the models. Overall, this investigation yields important insights for optimizing open holes and elevating the tensile performance of SS400 sheet specimens.

Research of immune clone algorithm applying in the LED lamp automatic lock screw workstation

A new automatic lock screw machine for LED lamp has been researched in the paper, which is based on the immune clone algorithm. Firstly, the robot automatic lock screw system has been setup. Vision sensor captured LED lampshade images in real-time. Median filtering operation has been performed to the captured images. On this basis, a new image segmentation method based on the immune clone algorithm has been researched. The antibody and antigen of LED lampshade image have been defined. The immune affinity function has been setup at the same time. Several artificial immune operators have been designed, which can be used to obtain the optimum image segmentation threshold value in real time. The final results showed that the optimum image threshold value can been obtained after less than ten times iterative computation. Compared with the traditional Ostu method, the new method can reduce the disturbance information around the threaded hole, which made basis for threaded hole recognition and location.

Numerical investigation of steel beams with web openings obtained from topology optimisation

The use of web openings in I-section beams has become increasingly common in recent years, and these elements can be observed in various civil engineering applications. This design approach results in an improved weight-to-stiffness ratio in steel beams, enabling their use over longer spans without a significant increase in material cost and deflections due to self-weight. It also avoids the cutting of holes in inappropriate locations for electrical, hydraulic, and air conditioning installations. Steel beams fabricated with web openings also represent an important solution when height constraints are imposed on multi-story buildings due to design regulations and economic considerations. It is recognised that the use of the traditional web opening shapes - namely, circular, rectangular, and hexagonal - in civil structures can lead to issues associated with high stress concentration. The presence of these web openings can induce local instability or yielding due to inadequate shear force transfer across the openings, allowing plastic hinge formations, also known as Vierendeel mechanism, for instance. In this sense, researchers have investigated novel shapes to mitigate the impacts of the web openings in both structural and economic terms. In this sense, this work has been developed aiming to evaluate the structural performance of I-section beams obtained using structural optimisation, for a reference distributed load and different boundary conditions, compared with the cellular beams. An evaluation of the structural potential of the obtained topologies has been performed by linear elastic, buckling and complete nonlinear analyses. Results were obtained in terms of stresses, displacements, and ultimate loads for all investigated cases. It was found that when compared to a cellular beam, the optimised beams increased the ultimate resistance with superior stiffness resulting in lower displacements and presented a more adequate stress distribution with lower stress concentration. However, in some cases a poor structural performance was observed due to large zones with holes obtained from the optimisation process. Based on these results and on the work of Tsavdaridis et al., authors proposed a configuration for the openings, and its structural performance proved it to be a promising solution to be employed on beams with web openings, especially when the expected failure mode is lateral-torsional buckling. A parametric study was conducted to assess the efficiency of the proposed configuration for different steel profiles and span lengths; results indicated equivalent or superior load capacity when compared to the reference cellular beam. The configuration suggested by the authors can be easily fabricated, and, considering the constant patterns along the length, finding an expression to determine its design load is possible, like what is usually done for other shapes (circular, hexagonal).

Location and Extents of Scour Hole around an Erodible Spill-through Abutment under Clear Water Condition and the Abutment Classification

Bridge abutment scour is a complex phenomenon, which significantly affects bridge stability and is responsible for the damage and failures of many bridges over waterways across the world. Given the widespread and devastating human and societal costs, numerous experimental studies have been conducted to find the mechanisms of bridge abutment scour, and several empirical and mathematical prediction models are available. However, the location of the scour hole and its extents have not been investigated in detail, which is one of the important parameters, not only for the bridge stability itself, but also for the safety of structures around the bridge and their design. Thus, in this study, laboratory experiments were carried out using several different lengths of erodible abutment under different flow conditions to suggest a new mathematical criterion for abutment classification with respect to the location of scour holes. Furthermore, additional analysis was conducted to locate the point of the deepest scour depth and extent of the scour hole around the abutment. Both in transverse and flow direction, the location of the scour hole and the point of the deepest scour are governed by the geometric contraction ratio. This research will be useful in analyzing the bridge safety itself as well as safety of the river training works close to the bridge with respect to the location and extents of the scour hole.

In situ damage propagation and fracture in notched cross-ply SiC/SiC composites: Experiment and numerical modeling

In this paper, the damage progression and fracture behavior in notched cross-ply SiC/SiC composites were investigated using the in situ digital image correlation (DIC) and acoustic emission (AE) techniques. Under tensile loading, the mechanical properties of composite’s elastic modulus, proportional limit stress (PLS), ultimate tensile strength (UTS), and fracture strain were obtained for non-notched, single-hole, double-holes, and four-holes samples. Based on the analysis of composite’s tangent modulus, the nonlinear tensile stress-strain curves were divided into three main domains, relating with internal multiple damage mechanisms observed using the in situ DIC and AE. Effects of the number and location of the circular holes on the full-filed composite’s damage and strain evolution, AE energy and ring-down count were investigated. After tensile fracture, the composite’s macro fracture morphology and micro damage mechanisms were observed under the scanning electronic microscopy (SEM). Numerical modeling of tensile damage and fracture process of different notched samples were conducted using the extend finite element method (XFEM). Relationships between the notch types, tensile mechanical properties, macro strain evolution, and micro damage mechanisms were established.

Does gravitational time dilation influence the propagation of the change of gravitational field?

This article uses thought experiments and strict logical deductions to discuss the propagation the change of gravity field and find that all current gravity fields are generated some time before and they are not static but are constantly propagating. If there is a change of the gravity field of a celestial body, it takes time for this change to propagate before interacting with this another celestial body. However, for a binary black hole system, the positions of the two black holes constantly changes relative to each other, resulting in changes of the gravity fields of both black holes, and, it also takes time for the change of gravity field of one black hole to reach the other black hole. If gravitational time dilation governs, it takes forever for the change of the gravity field of one black hole to propagate across the event horizon of the other black hole and interact gravitationally with it. If so, one black hole will never be able to respond to the change of the location of the other black hole. This is impossible. Thus, gravitational time dilation should not have the same influence upon the propagation of the change of gravity field as it has on light.

Design Optimization of Rotor Bridge and Fixing Hole for Spoke-Type PMSM

This paper investigates the performance of the spoke-type permanent magnet synchronous motors (PMSMs) for driving systems. The electromagnetic performance of the PMSMs with different rotor bridges and fixing holes is studied, including the no-load characteristic, cogging torque, output torque, and torque ripple. The structures of the rotor bridge and location of the fixing holes in the rotor core are optimized to increase the output torque capability. The results show that the output torque of the single side bridge is increased due to the reduction of the leakage flux compared with the double side bridge structure. The motor with the inner side bridge design has the highest output torque. Furthermore, the mechanical strength of the three rotors at the maximum speed is investigated by finite-element analysis (FEA) to verify the feasibility of the structures. Finally, two 3000r/min 10kW prototypes have been manufactured and the experimental results validate the analysis methods in this paper.

Finite Element Modelling of Rubber-Metal Vibration Isolators with Holes for the Vibration Protection System of Buildings

The article presents a calculation of rubber-metal vibration isolators with five holes of different diameters using a software package that implements the finite element method. A comparative analysis of the Eigen frequencies of rubber-metal vibration isolators with five holes (one in the center, 4 symmetrically at the corners) and without holes is presented. Finite element models of a rubber-metal vibration isolator with and without holes are modeled, and their characteristics are analyzed. The results show that vibration isolators with several symmetrically located holes have several advantages in a number of parameters to vibration isolators without holes, and, therefore, can be used for vibration isolation of buildings, especially in the case of delayed installation of vibration protection.

ALMA 300 pc Resolution Imaging of a z = 6.79 Quasar: No Evidence for Supermassive Black Hole Influence on the C ii Kinematics

We present Atacama Large Millimeter/submillimeter Array (ALMA) [C ii] 158 μm and dust continuum observations of the z = 6.79 quasar J0109–3047 at a resolution of 0.″045 (∼300 pc). The dust and [C ii] emission are enclosed within a ∼500 pc radius, with the central beam (r < 144 pc) accounting for ∼25% (8%) of the total continuum ([C ii]) emission. The far-infrared (FIR) luminosity density increases radially from ∼5 × 1011 L ⊙ kpc−2 to a central value of ∼70 × 1011 L ⊙ kpc−2 (SFRD ∼50–700 M ⊙yr−1 kpc−2). The [C ii] kinematics are dispersion dominated with a constant velocity dispersion of 137 ± 6 km s−1. The constant dispersion implies that the underlying mass distribution is not centrally peaked, consistent with the expectations of a flat gas mass profile. The lack of an upturn in velocity dispersion within the central beam is inconsistent with a black hole mass greater than M BH < 6.5 × 108 M ⊙ (2σ level), unless highly fine-tuned changes in the interstellar medium properties conspire to produce a decrease of the gas mass in the central beam comparable to the black hole mass. Our observations therefore imply either that (a) the black hole is less massive than previously measured, or (b) the central peak of the FIR and [C ii] emission are not tracing the location of the black hole, as suggested by the tentative offset between the near-infrared position of the quasar and the ALMA continuum emission.

Effect of Pin Holes Location of Unicompartmental Knee Arthroplasty on Postoperative Tibial Plateau Mechanical Properties

The purpose of this study is to explore the biomechanical characteristics of the tibia after unicompartmental knee arthroplasty with different distributions of two-pin holes, and to optimize the two-pin holes scheme to reduce the risk of tibial fractures after unicompartmental knee arthroplasty. Lower limbs model is segmented and reconstructed from computed tomography images. Four combinations of two pin holes created for tibial cutting guide placement are simulated with finite element analysis. In the third mode, the positioning hole at the proximal medial edge of the tibial plateau has the highest stress value, and the position of the positioning hole near the medial edge of the proximal tibial plateau appears stress concentration. The present study revealed that placing tibial cutting guide holding pins centrally would lower the risks of periprosthetic fracture of the medial tibial plateau.

Preoperative estimation of retinal hole location using ultra-wide-field imaging.

Accurate localization of retinal holes is essential for successful scleral buckling (SB) surgery. We aimed to verify the feasibility of using ultra-wide-field (UWF) imaging for preoperative estimation of retinal hole location. We observed 21 eyes from 21 patients with rhegmatogenous retinal detachment (RRD) who underwent successful SB. They were treated at the Department of Ophthalmology of the Second Hospital of Hebei Medical University between November 2020 and November 2021. UWF fundus photography using an Optos device was performed at different steering positions 1 day before, 1 day after, and 1 month after SB. Using the preoperative fundus images, we measured the transverse diameter of the optic disc (D1) and the distance from the centre of the retinal holes to the ora serrata (D2). The accurate transverse diameter of the optic disc (Dd) was measured preoperatively using optical coherence tomography. The same surgeon measured the scleral chord lengths intraoperatively from the limbus to the located retinal hole marked on the sclera using an ophthalmic calliper. Statistical software was used to analyze the consistency of scleral chord length between the retinal hole and the limbus, which was estimated by preoperative UWF imaging and was measured using an ophthalmic calliper intraoperatively. There was no statistically significant difference in the scleral chord length between the retinal holes and the limbus, which was estimated by preoperative UWF fundus photography and was measured by the calliper during surgery. It is feasible to locate retinal holes using UWF fundus photography before SB, which is helpful for quick localization, thereby reducing the learning curve of SB surgery.

Discrete element analysis of dynamic characteristics and earthquake collapse of solid structure ancient masonry pagoda

In order to investigate the seismic damage and collapse mechanism of ancient masonry pagodas, a numerical model of the Tang Dynasty masonry pagoda (Xuanzang Pagoda) located at Xingjiao Temple was established using the discrete element software 3DEC, and non-linear mechanical parameters of the contact surfaces between rigid blocks were defined. Dynamic characteristics were analyzed, and the seismic response of the ancient pagoda was calculated by inputting El-Centro waves, Tianjin waves, and Lanzhou artificial waves with different intensities in three directions. The study analyzed the damage failure process of the pagoda, identified vulnerable areas, and obtained its collapse.The results show that the ancient pagoda behaves as an elastic–plastic system at intensity 7 degree seismic action. The acceleration response of the floors increases along the height, and the displacement angle between floors appears as an inflection point at the second floor. The middle floors are especially vulnerable to damage due to low cohesion and strong movements of the internal soil fill. As the intensity increases, significant damage occurs, with rapid floor displacement response and upward extension of cracks. The top floor of the ancient pagoda collapses first with stair-shaped oblique cracks, followed by a floor-by-floor destruction from top to bottom. The collapse of floors with different hole locations also vary. These findings provide valuable insights for predicting the vulnerable areas and collapse of Xuanzang Pagoda under seismic action.

Near-perfect retroreflection of flexural waves via optimized elastic metagratings

The potential of elastic wave retroreflection is substantial for various applications such as structural identification and detection. However, realizing accurate retroreflection presents significant challenges owing to the need for high-efficiency anomalous reflection from boundaries. This study delves into the relatively less-explored field of flexural wave retroreflection in thin plates and proposes the use of metagratings for its realization. The present metagratings, which are built from unit cells created by possibly-overlapping circular holes, offer a simple fabrication process owing to their straightforward geometry. They hold an advantage over metasurfaces, which often struggle with wave steering because of their unmanageable higher-order diffraction modes. However, no systematic approach has been proposed so far to design metagratings for flexural wave retroreflection. To address this gap, we have established an optimization problem that identifies the optimal geometries and locations of the circular holes built into the proposed retroreflecting metagratings using a gradient-based optimizer. The design process involves diffraction grating theory and spatial fast Fourier transform. Both single and multiple retroreflections at various angles were considered and the numerical findings were substantiated by experimental results. The findings of this study imply that the investigated metagratings and design approaches have promising potential for more sophisticated wave manipulations.

Spatial–Temporal Influence of Sand Dams on Chemical and Microbial Properties of Water from Scooping Holes in Degraded Semi-Arid Regions

Communities in semi-arid lands use sand dams to enhance access water during the dry seasons. However, there is limited information on the quality of water derived from these sand dams, especially in degraded lands where storm surface runoff poses contamination risk. Thus, this study aimed at assessing the spatial–temporal variations in water quality of sand dams in Chepareria, West Pokot County in Kenya. Water samples were collected from scooping holes across 18 purposefully selected sand dams. Results obtained showed significant differences in water quality based on a sand dam’s age and location of the scooping holes, but the magnitude of these differences differed with specific properties. For instance, in recently constructed sand dams (&lt;1 year), scooping holes near the sand dam wall had lower pH values (8.5) than holes scooped a distance from the sand dam wall (9.2). For total dissolved solutes and microbial properties, sand dam age had the greatest impact, over the location of the scooping holes. For example, water obtained from &lt;1 year old sand dams had significantly higher TDS with an average value of 100.3 mg L−1. The thermotolerant coliforms (TTC) exceeded the maximum allowable levels recommended by The World Health Organization. Thus, water obtained from these sand dams should be treated before consumption. Finally, sand dams meant for domestic water harvesting should be protected. Shallow wells with appropriate aprons for effective protection against contamination should be installed to enhance abstraction of safe water from sand dams.

Analytical method for distortional buckling load of cold-formed steel members with perforated web under bending moment

In order to reduce weight or meet specific functional requirements, cold-formed steel (CFS) members with perforated webs are widely used in practical engineering. However, these web holes, especially the un-stiffened ones, can result in stress concentrations and section deficiencies, leading to a reduction of the distortional buckling load. Existing specifications, such as the American Iron and Steel Institute (AISI 2016) and Australia New Zealand Standards (AS/NZS 4600:2018), do not fully consider this impact. By simplifying the perforated web into an equivalent beam model and modifying the calculation method of the web rotational stiffness, this paper proposes an analytical method for the distortional buckling load of perforated CFS members with arbitrary hole parameters, including the hole spacing, location, and geometric shape. The proposed method is verified by finite element analysis (FEA) and experiment results in the literature. The FEA result indicates that holes near the compressed flange or with smaller spacing can lead to more reduction in the distortional buckling load. Compared to existing methods, the calculation accuracy of the proposed method has been improved by 2% to 4%.