Hole Position Research Articles

Coupled Focused Acoustic Vortices Generated by Degenerated Artificial Plates for Acoustic Coded Communication

AbstractAcoustic vortices (AVs) show great significance in acoustic communication. However, the lack of confidentiality and the cross‐talks in communications based on traditional AVs remain problems. Here, a degenerated centrosymmetric circular hole plate (DCHP) is designed to generate coupled focused acoustic vortices (CFAVs) with pure orbital angular momentums (OAMs) in both air and water. When an acoustic plane wave transmits through DCHP, two focused acoustic vortices (FAVs) with opposite topological charges are produced simultaneously, and the coupling between them results in a focused acoustic petal beam (FAPB). The OAM of the CFAV can be simply modulated by the angular interval of the adjacent holes on DCHP and the CFAV can be focused at any distances by adjusting the positions of holes. The DCHPs are demonstrated to be able to generate FAPBs numerically and experimentally. Furthermore, 8 FAPBs with different OAMs are set as 8 bases to represent 8 bits of ASCII binary code, and the information encoding and decoding for acoustic communication are realized in water using them. The proposed DCHP provides a convenient method to achieve CFAVs, which may be helpful to enhance the security, reduce the false information, and increase the information capacity in acoustic communication.

Scattering of a scalene trapezoidal hill with a shallow cavity to SH waves

Abstract Both surface ground motion and cavity stress concentration have always been considered in the designs of earthquake engineering. In this paper, a theoretical approach is used to study the scattering problem of circular holes under a scalene trapezoidal hill. The wave displacement function was obtained by solving the Helmholtz equation that meets the zero-stress boundary conditions by the variable separation method and the image method. Based on the complex function, the multipolar coordinate method and the region-matching technique, algebraic equations were established at auxiliary boundaries and free boundary conditions in the complex domain. Auxiliary circles were used to solve the singularity of the reflex angle at the trapezoidal corner. Then, according to the sample statistics, instead of the Fourier expansion method, the least-squares method was used to solve the undetermined coefficient of the algebraic equations by discrete boundaries. Frequency responses for some parameters were calculated and discussed. The numerical results demonstrate that the continuity of the auxiliary boundaries and the accuracy of the zero-stress boundary are good; the displacement of the free surface and the stress of the circular hole are related to the shape of the trapezoid, the position of the circular hole, the direction of the incident wave and the frequency content of the excitation. Finally, time-domain responses were calculated by inverse fast Fourier transform based on the frequency domain theory, and the results have revealed the wave propagation mechanism in the complicated structure.

Short-Segment Drilling Guides for the Management Comminuted Mandibular Fractures.

Treatment of a severely comminuted mandibular fracture is challenging. This technical note describes a novel office-based workflow, combining virtual surgery planning with short-segment drilling guides. The authors reduced the comminuted mandibular fractures via virtual surgery planning. Then, the reconstructed mandible model was printed using an in-house 3D printer. Next, the reconstruction plate was preformed according to the shape of the mandibular model surface, and the position of the screw hole in the mandibular surface was determined. Finally, hand-made short-segment drilling guides for screw position transfer were fabricated with temporary resin. During the operation, the authors reset the guides for the drill to make screw holes as planned. After the hole was drilled, the pre-bent plate was applied to the mandible. The fracture was expected to be reduced, when tightening the screws. in our workflow, by using short and simple operative procedures, the authors were able to achieve precise reduction and reduce the operation time.

Combined effects of bleed hole extraction and rotation on internal heat transfer in a ribbed two-pass channel

Serpentine passages arranged with ribs, are commonly used to guide the cooling air and remove heat transferred from hot gas. In this study, the effects of bleed hole extraction on internal heat transfer of ribbed channel are numerically studied in a rotating frame. Three positions of bleed hole are studied as rotation number ranges from 0 to 0.2. The flow structure and heat transfer features are depicted and evaluated through qualitative and quantitative analysis. Numerical results reveal that heat transfer distribution features are quite different for channel with bleed holes at different locations. The allocation of bleed hole extraction flowrate varies distinctively under rotating condition. Rotation is responsible for affecting the flow reattachment and corresponding secondary vortex structures, and consequently heat transfer features. Channels rotated in clockwise and counter-clockwise direction share opposite Coriolis force acting direction, thus effects of heat transfer augmentation are different. The effects of bleed hole position on local heat transfer are more pronounced on the endwall opposite to the endwall where the Coriolis force acts. Channel with bleed holes at upstream position shows the poorest heat transfer enhancement at inter-rib regions, with maximum reduction by 11.4% under stationary condition and 13.2% under rotating condition.

Risk Factors for Implant Removal After Surgical Fixation of Midshaft Clavicle Fractures.

Midshaft clavicle fractures are common injuries that traditionally have been managed nonoperatively. However, recent literature has shown lower rates of nonunion and improved patient-reported outcomes with surgical management. The rate of implant removal after surgical fixation varies across the literature from 5% to 82%, depending on the method of fixation. We performed a retrospective review of all patients who underwent open reduction and internal fixation (ORIF) with plate-and-screw constructs for midshaft fractures of the clavicle at 2 level I trauma centers to determine the rate of implant removal and identify variables associated with implant removal. We collected all patient-, injury-, and treatment-specific factors as well as information on reoperation for removal of implants. Bivariate analysis and multivariable logistic regression analysis were used to assess whether explanatory factors were associated with removal of implants after ORIF for midshaft clavicle fractures. Of the 146 patients who were treated with ORIF for midshaft clavicle fractures with plate-and-screw constructs, 41 (28%) underwent removal of the implant. The median follow-up was 836 days (interquartile range, 457-1567 days). Variables associated with increased risk of implant removal included anterior plate position (odds ratio, 5.32; 95% CI, 2.01-14.1) and number of holes in the plate (odds ratio, 1.28; 95% CI, 1.00-1.63). These results question whether anterior plating results in less implant prominence and less subsequent removal of implants. [Orthopedics. 2022;45(4):e201-e206.].

The influence of introducing holes on the generation of skyrmions in nanofilms

We present a novel method to form multiple skyrmions by introducing holes and to control the forming locations of the skyrmions by controlling the positions of holes. It is found that the more holes, the more likely to induce more skyrmions. Both increasing the spacing and choosing the appropriate size of the holes are conducive to the generation of more skyrmions. Furthermore, skyrmions are usually formed in the center of the space around the holes under the appropriate fields. According to analyzing the hysteresis loops of the films with different geometry, we find that the holes influence the ability of the films to form skyrmions. The larger the hole spacing, the smaller the loop area and the stronger the ability to generate skyrmions in the films. These results are beneficial for the application of skyrmions in the future.

A predatory gastropod as the potential biological control agent of the Korean invasive mussel, Mytilus galloprovincialis (Lamarck, 1819)

The classical biological control, which is the intentional introduction of exotic species to manage the biological invasion, is the standard measure if the human-mediated management is no longer effective. This method, however, involves a latent risk that the introduced exotic species brings about the nontarget effect on indigenous native species. Applying the native natural predator is the best alternative to control the invasive alien species without the substantial change into the ecosystem of the area invaded. Here, we introduced an indigenous Korean muricid gastropod Reishia bronni (Dunker, 1860), a potential natural predator of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819), a well-known invasive alien species successfully settled down in Korea. In the biomonitoring survey on the Korean ports of the east coast between 2007 and 2011, we have observed the spread of R. bronni within the Mytilus galloprovincialis community. The observed decrease of the mussel density around the gastropod assemblage led us to the idea that R. bronni is the natural predator of M. galloprovincialis . In order to clarify such a predator-prey interaction between both species, we performed a field observation from two Korean ports in August 2012, keeping R. bronni and M. galloprovincialis individuals together into the cages for 18 days. Then, we counted the number of latter ones consumed and estimated the average time spent feeding per individual of R. bronni . We observed the positions of the drill holes made on the consumed shells by it. Our results showed that R. bronni is the active natural predator of M. galloprovincialis with the high feeding intensity and the unique foraging behavior targeting the lateral margin of the shell, so-called “Marginal drilling”. Therefore, we could suggest the possibility that R. bronni can be applied to control the mass spread of M. galloprovincialis .

Research on Probability Analysis Technology of Circular Section Cabin Socket Structure Based on APDL

In the strength design of sleeve joint structure, manufacturing tolerance and fit clearance are generally ignored. The load of connecting screw is usually calculated by the method of linear distribution. The contact force between screw and cabin is usually simulated by deterministic finite element method. The command flow of probability analysis for typical circular section socket structure is developed based on APDL. The uncertainty of manufacturing tolerance and fit clearance for socket structure is defined as random input variables, such as the cabin diameter, cabin hole position, and cabin aperture and so on. Monte Carlo method is used in probability analysis, and the input variables are random uniform distribution. The analysis results show that the transfer load of screws is redistributed under the probability analysis compared with the finite element analysis, and some screws bear larger load, while the nearby screws bear smaller load. At the same time, the load transferred by screw is not only affected by its own variables, but also by others. The probability analysis method can fully consider the influence of manufacturing tolerance of the structure, and evaluate the structural strength margin more accurately. It can not only prevent the harm caused by uncertainty of random manufacturing tolerance, but also prevent over design caused by conservative method.

Influence of artificial roughness parametric variation on thermal performance of solar thermal collector: An experimental study, response surface analysis and ANN modelling

The influence of the attack angle (αa) of the perforated baffles on thermohydraulic performance ηp of a solar thermal collector (STC) has been investigated experimentally. The experimentations have been performed to obtain the Nusselt number (Nurs) and friction factor (frs) by varying Reynolds number (Re) from 5000 to 17,000 and αa from 35° to 65°. The other geometrical parameters of angled perforated baffles are fixed in accordance with previous studies. The relative baffle height HB/HD , relative baffle pitch PB/HB , relative hole position OB/HB and open area ratio β0 are fixed at 0.50, 10, 0.266 and 12% respectively. The STC with roughened angled perforated baffles improves the Nurs and frs by 3.82 and 7.14 times respectively as compared to STC without baffles wall. The angled perforated baffles at αa of 55° provides highest thermo-hydraulic performance at Re of 9000. A thermo-hydraulic performance of 1.94 is obtained for the array of designed parameters. The statistical correlations are established for the Nurs and frs by using experimental data. The correlations obtained for the Nurs and frs predict the experimental results within a variation of ±9.7% and ±5.0% respectively. Central Composite Design (CCD) of thermo-hydraulic performance parameters is carried for the surface response analysis. Modelling of thermal parameters using CCD and Artificial Neural Network (ANN) is done which predict them with good accuracy. The previously studies on STC roughened with various types of roughness show appreciable heat transfer enhancement but very few studies have utilized angled perforated baffles. As per author knowledge, a comprehensive study on the performance analysis of STC roughened with angled perforated baffles using different techniques is not available. The study become novel because in addition to the experimental examination of STC performance, correlations for Nurs and frs from experimental data are developed and modelling of thermal parameters using CCD and Artificial Neural Network (ANN) is also performed.

How the Universe postpones the evaporation and curtails the quantum spreading of black holes

Black holes are expected to evaporate through the process of Hawking radiation. This process is expected to cause the uncertainty in a black hole's position to grow to $\sim M^2/M_{Pl}^3$ over the course of it's lifetime, even as its momentum spreads only by $\sim M_{Pl}$. For the black holes that have been observed, which have $M\geq M_\odot$, this greatly exceeds the Hubble volume. However, the decay of black holes and their quantum spreading, are delayed in the Universe while the influx of energy into the black holes exceeds their Hawking luminosity. We show that for these $M\geq M_\odot$ black holes, their decay outside galaxies and clusters is prevented far longer than it takes the black holes to be dragged well beyond the Hubble horizon, where their eventual decay occurs away from the prying eyes of any observer who has not hitched a ride with them. Meanwhile, black holes in an observer's galaxy or cluster are themselves prevented from decaying long past the extinction of the last stars, and at least until their galaxy/cluster is swept clean of dark matter, in $\gg 10^{25}$y. Even then, if the black holes become unbound they are dragged beyond the Hubble radius before undergoing significant decay; if not, they remain in bound orbits, spreading at most over a subvolume of the galaxy/cluster, and long localized by scatterings to much smaller volumes.

Fracture phase field modeling of 3D stitched composite with optimized suture design

Stitch, a flexible method of enhancing interlayer toughness, is widely applied in engineering. The strength of sutures with various stitching patterns dominates the interlaminar fracture toughness. Understanding the breakage process of sutures is vital to determine the interlayer failure of laminated composites. The failure modes of the stitches, however, have proven challenging to predict due to a series of potential complex responses such as debonding, interfacial crack, edge delamination, and breakage. In this paper, we propose a new phase field scheme to explore the progressive failure mechanism of single and multiple stitches, leveraging the advantages of the phase field method for complex fractures without introducing additional failure criteria. We reconstruct the phase field driving force by considering both tensile and compressive components of strain energy in the phase field evolution to deal with multiple forms of damage simultaneously. The fracture energy is modified to distinguish mode-I and mode-II fracture toughness. The zero-thickness smeared interface model is derived from the original allocation with a thin interphase layer by asymptotic analysis, effectively approximating the coherent imperfect interface between sutures and polymer matrix. The feasibility of the developed phase field scheme is verified through benchmark examples and experiments. The stepped fracture process and strength of 3D stitched composites with various stitching patterns are examined and compared with each other to reveal the fracture laws and damage mechanism. This study implies that the failure of the stitching system is strongly associated with the structural symmetry, closure, and distribution of the hole positions. On this basis, a new stitching strategy is proposed with a 13% enhancement in tensile strength with identical stitching density, which can be further extended to optimize the bearing capacity of multilayer structures with more complex stitching patterns.

Design of a dielectric chiral micro-structured fiber applied in a fiber optic current sensor

During the process of drawing the screwed silicon-based fiber, there will be a uniform rotation rate in it, which results in a decrease of circular polarization degree of the fiber. In order to solve this problem, we presented a kind of dielectric chiral micro-structured fiber owing higher circular polarization degree. Meanwhile, the air holes of fiber will collapse during the progress of fiber drawing, which will change the position of air holes. As a result, the circular polarization degree of the fiber decreases. In order to reduce the change of circular polarization degree caused by the position fluctuation of the air holes, a highly symmetrical micro-structured dielectric chiral fiber was firstly designed in this paper. Then, we established a physical error model considering the fluctuation of the air holes’ position which was the design basis of the air holes’ position, size, and chiral parameters of the specific microstructure fiber. Next, comparing the circular polarization degree S3 of screwed silicon-based fiber and that of the dielectric chiral micro-structured fiber by simulation, it was proved that the dielectric chiral micro-structured fiber we designed has a higher circular polarization degree S3 than that of screwed silicon-based fiber. Finally, we applied the fiber designed in this paper as the fiber sensing coil in a fiber optic current sensor, and compared it with the fiber optic current sensor utilizing the original fiber sensing coil in ratio error. The simulation results proved that compared with the original system, dielectric chiral micro-structured fiber utilized as the fiber sensing coil in a fiber optic current sensor will decrease the ratio error by an order of magnitude in theory.

Design of high-birefringence photonic crystal fiber based on As2Se3

A photonic crystal fiber is designed with chalcogenide glass As2Se3 as the base material. As2Se3 has a high refractive index and a high nonlinear refractive index; as a result, it has a desired application for strengthening birefringence and nonlinearity. The outer layer of the fiber is a regular decagonal structure composed of four layers of circular air holes, and the inner cladding area is composed of four elliptical air holes arranged in a diamond pattern. The influence of the size of the circular air holes in the fiber cladding, the thickness between each layer, and the size and position of the elliptical air holes in the inner cladding area on the birefringence is analyzed and studied using the full vector finite element method. The results show that the birefringence value of the fundamental mode of the fibers is 0.108 at a wavelength of 1.55 μm, and at the same time, the nonlinear coefficients of the X and Y polarization states are 240 and 197 m − 1 · W − 1, respectively.

Research on Position Tracking Algorithm with Vision Sensor for the Auto Liquid Filling Machine

The liquid filling machine is used in packaging fields such as food, chemistry, and oil industries. In particular, the machines are used to package products in drums after manufacturing products in hazardous chemical factories. Existing filling machine allows the operator to directly inject the product and set the injection capacity only to the standard drum. In this paper, we propose position tracking algorithm with a vision sensor that can track the inlet location of various types of drums. Hough transform detection method is used to search for objects in images from the vision sensor. The proposed algorithm can calculate the position of the injection hole after extracting the feature points so that it is possible to inject the product by automatically moving the injection nozzle. Therefore, it expected that the developed algorithm for the automatic liquid filling machine will give more production and save a lot of manpower for packaging industry.

Adaptive XIGA shakedown analysis for problems with holes

Shakedown analysis plays a substantial role in safety assessment, especially in nuclear plant industry, chemical industry and civil engineering. This paper presents numerical investigations of shakedown problems with holes using the adaptive extended isogeometric analysis (XIGA). An adaptive strategy performed in the discretized framework of a kinematic approach and second-order cone programming (SOCP) is presented. The main idea is to integrate XIGA based on locally refined non-uniform rational B-splines (LR NURBS) into the SOCP to form an efficient approach for shakedown analysis. A SOCP form based on the von Mises yield criterion is established. By means of an effective SOCP solver, the arising optimization problem is then solved. In addition, the level set function is adopted to detect the position of holes. The L2-norm of plastic strain rates is used to guide local mesh refinement. The merits of the developed approach are its easy implementation and high computational efficiency. We consider several benchmark examples to illustrate the accuracy, reliability and efficiency of the developed method.

Vertical Stratification of Insect Species Developing in Water-Filled Tree Holes

Forest ecosystems have a distinct vertical dimension, but the structuring of communities in this three-dimensional space is not well understood. Water-filled tree holes are natural microcosms structured in metacommunities. Here, we used these microcosms as model systems to analyze how insect communities and the occurrence and abundance of individual species are influenced by biotic and abiotic microhabitat characteristics, the vertical position of the tree hole, and stand-scale habitat availability. We found that both the characteristics of water-filled tree holes and their insect communities differ significantly between canopy and ground level. Individual insect species showed contrasting responses to the vertical position of the tree holes when important environmental factors at the stand and the tree-hole scale were considered. While some species, such as the mosquito Aedes geniculatus and the beetle Prionocyphon serricornis, decreased in abundance with increasing tree-hole height, the biting midge Dasyhelea sp., the non-biting midge Metriocnemus cavicola and the hoverfly Myiatropa florea increased in abundance. Our results suggest that vertical stratification in forests is most likely driven not only by variation in tree-hole microhabitat properties, i.e., niche separation, but also by individual species traits, such as adult dispersal propensity, food preferences and mating behavior of adult stages, and interspecific competition of larval stages. Therefore, communities of insect species developing in tree holes are likely structured by competition–colonization trade-offs predicted by metacommunity theory.

Preoperative Predictions of Distal Screw Length for the Osteosynthesis of Distal Radius Fractures.

Background: The objective of this study was to clarify whether anteroposterior dimension of the radius along the screw axis of a fixed angle volar locking plate (VLP) can be predicted from the width of the radius on the VLP. Methods: Sixty-nine wrists in 68 patients with distal radius fractures that underwent fixation with a fixed angle VLPs were evaluated. All patients underwent pre- and postoperative computed tomographic scans of the distal radius. The transverse width of the radius was measured at the position of the third screw hole from the proximal edge. The anteroposterior dimension of the radius (R) was measured along the axes of the distal screws. The distal row screw holes were defined as R1, R2, R3, and R4 from the radial to the ulnar side. Correlation analysis between the width and the anteroposterior dimension, and single regression analysis were performed for each screw hole. The correlations amongst the R values for the different distal row screws were also assessed. Results: The correlation coefficients between the transverse width and anteroposterior dimensions were 0.54, 0.58, 0.55, and 0.42 for R1, R2, R3, and R4 respectively (p < 0.05). The regression equations were R1 = 0.49W + 7.99, R2 = 0.47W + 11.8, R3 = 0.52W + 10.8, and R4 = 0.41W + 11.5 respectively. The correlation coefficients among anteroposterior dimensions were 0.85, 0.64, 0.59, 0.70, 0.61, and 0.80 for R1/R2, R1/R3, R1/R4, R2/R3, R2/R4, and R3/R4 respectively (p < 0.01). Conclusions: There were significant correlations in the anteroposterior dimensions amongst the distal row screw lengths. The regression equations used in this study may be helpful to predict the length of distal row screw and prevent complications due to inappropriate screw choices. Level of Evidence: Level III (Therapeutic).

Direct-focusing surface-emitting laser.

Focusing is a fundamental optical technique that has been widely implemented via lenses. Here, we demonstrate direct focusing from a band-edge surface-emitting laser, whose emission area is 200 µm × 200 µm, without any lenses. To achieve this, a phase-modulating layer is incorporated into the laser cavity. This layer acts simultaneously as a lasing cavity similar to that of a photonic crystal laser and as a holographic spatial-phase modulator, which transforms the output beam into a focusing beam by slightly shifting the positions of holes from a periodic square lattice. Beam profiles along the surface normal clearly show that direct focusing occurs with a focal length and focal spot size of 310 µm and 6.1 µm, respectively. The focal length agrees well with the theoretical value, and the focal spot size is 2.0 times the diffraction-limited size, which indicates that the higher transverse modes are sufficiently suppressed. In addition, the power density at the focus is 540 times higher than that at the near-field plane. Interestingly, a focus pattern is also observed in the opposite direction at the near-field plane, which indicates that a converging beam and a diverging beam are simultaneously emitted because of the nature of the in-plane band-edge laser. The conventional beam patterns of semiconductor laser cavities are limited to the regime of two-dimensional projection based on a Fourier hologram. In contrast, we demonstrate the simplest form of a three-dimensional point cloud based on a Fresnel hologram, which is quite useful for micro-sensing applications such as microfluidics, flow cytometry, blood sensors, and endoscopy.

Photon escape in the extremal Kerr black hole spacetime

We consider necessary and sufficient conditions for photons emitted from an arbitrary spacetime position of the extremal Kerr black hole to escape to infinity. The radial equation of motion determines the necessary conditions for photons emitted from $r=r_*$ to escape to infinity, and the polar angle equation of motion further restricts the allowed region of photon motion. From these two conditions, we provide a method to visualize a two-dimensional photon impact parameter space that allows photons to escape to infinity, i.e., the escapable region. Finally, we completely identify the escapable region for the extremal Kerr black hole spacetime. This study has generalized our previous result [K.~Ogasawara and T.~Igata, Phys. Rev. D \textbf{103}, 044029 (2021)], which focused only on light sources near the horizon, to the classification covering light sources in the entire region.

Influence of the balance hole on the performance of a gas–liquid two–phase centrifugal pump

Centrifugal pumps are prone to vibration due to unstable impeller forces under gas–liquid two-phase conditions. The balance hole can balance the axial force on the impeller and improve the operation stability of the pump. In this study, the influence of the balance hole on the performance of the multiphase pump is studied. By parameterizing the balance hole, the influences of the radial position, circumferential position and diameter of the balance hole on the external characteristics, gas-phase distribution and axial force of the multiphase pump are investigated. Results show that the balance hole degrades the centrifugal pump performance at small gas volume fraction (GVF). At high GVF, when the balance hole is located in the gas phase accumulation zone and the diameter is above 6 mm, the performance of the centrifugal pump will be improved. The balance hole can improve the distribution of gas-phase in the impeller, but the effect is limited to the local area around the balance hole. The effect of the balance hole on the axial force weakens as the centre position of the balance hole moves from the impeller inlet to the impeller outlet, increases with increased hole diameter and is less influenced by circumferential position.