Hole Position Research Articles

Experimental, analytical and numerical investigation on the capacity of composite glulam beams with holes

Holes in timber beams can significantly affect their bearing capacity. This paper presents an extensive experimental investigation of the effect of circular holes with and without plywood reinforcement on glulam joists behaviour. The tests consider the variability of hole position, number and diameter. In the second step, a finite element model based on fracture mechanics was developed and validated against the experimental force–displacement curves of thirteen configurations. The model reproduces crack initiation and propagation through the adoption of cohesive contact layers. The satisfactory agreement with the experimental data has been the base of extensive parametric analyses considering multiple beam and hole geometry selections and two load arrangements at the upper and lower side of the beam. Finally, the results of the parametric analyses, initially used for a qualitative understanding of the structural behaviour, are used for calibrating probabilistic capacity models of the capacity of simply-supported beams with circular holes. The mechanics-based probabilistic model calculates the capacity as the product between the analytical capacity associated with the reduced cross-section and an adimensional correction factor. The factor is expressed as a linear combination of a set of explanatory variables selected after a step-wise deletion process.

Physical Simulation Study on Flow Field Characteristics of Molten Steel in 70t Ladle Bottom Argon Blowing Process

In the LF refining process, argon blowing at the bottom of ladle can play an important role in unifying the composition and temperature of molten steel and removing inclusions. However, unreasonable bottom argon blowing process can also cause many problems. Slag entrapment and slag surface exposure may occur, affecting the steel quality. Since the working conditions of different enterprises are very different, corresponding optimization is required for specific parameters. There were some problems in 70t ladle of a steel plant, such as unclear control of bottom argon blowing system in different refining periods, unobvious floating removal effect of inclusions in ladle, high total oxygen content and large fluctuation, etc. In this study, a 1:3 physical model was established according to the similarity principle. Then, on this basis, the experimental schemes with different blowing hole positions and argon flow rates were designed for simulation experiments. By means of mixing time measurement, flow field display and oil film measurement, the optimal argon blowing position was double holes 6, 12 (2/3R), and the included angle between them was 135°. The optimal argon flow rate for wire feeding and soft blowing should be 7.6 L/min (corresponding to the actual production of 180 L/min) and 0.6 L/min (corresponding to the actual production of 15 L/min), respectively. According to this scheme, the industrial experiments showed that the contents of total oxygen and nitrogen in the whole process were reduced, the surface density of inclusions in billet was reduced by 11.81% on average, and calcium sulfide and various inclusions containing aluminum were reduced to varying degrees.

Double-face intelligent hole position planning method for precision blasting in roadways using a computer-controlled drill jumbo

Double-face intelligent hole position planning method for precision blasting in roadways using a computer-controlled drill jumbo

Drill Hole Optimization for Augmenting Structural Integrity

Structures develop cracks during the course of there life resulting in catastrophic failures. This can be reduced by drilling holes near the crack tip. Here the aspect of optimal position and size of the drill hole has been analysed. Additionally the effect of supplementary hole has also been made. Finite element code ANSYS was used for the analysis. To verify the fracture capabilities of ANSYS the results were corroborated using photoelastic techniques. It was observed that reduction in stress intensity factor to a great extent depends upon the position of the stop hole. Also it was observed that as the radius of the crack was increased the stress intensity factor increased. Creating supplementary hole further reduced the stress intensity factor. So it can be concluded that for employing the concept of drill hole its position and size should be accurately determined.

Optimization design of feed array structure for space-borne synthetic multi-beam antenna

To reduce the difficulty of engineering realization as much as possible on the premise of ensuring the performance of the feed network, a new design method of the multi-feed composite multi-beam antenna feed array is proposed. In the design process, the method of longitudinal subdivision and layering is used to solve the processing problem of complex large-scale electrical and small-sized devices. Then the multi-objective and multi-variable differential evolution algorithm is used to optimize the distribution position of each mounting hole to realize the optimal interface layout. The method is used to optimize the design of a multi-beam antenna feed array and the product object is produced and tested. The test results show the effectiveness of the design method. This method can be used to guide designers to carry out actual engineering design, shorten the design cycle, and improve the design quality.

Effect of gas injection holes on mixing and combustion in solid propellant ducted rockets

Combustion efficiency is an important parameter of the combustion chamber. Gas injection holes have an important influence on the mixing and combustion in solid propellant ducted rockets, but there is currently little research on gas injection holes. This paper describes numerical simulations of solid propellant ducted rocket combustion chambers, with the numerical method verified through a direct-connected experiment. We investigate the effect of adding injection holes to the gas generator nozzle on the mixing and combustion performance, and examine the mixing degree, combustion efficiency, and flow field characteristics. This paper focuses on the number and the position of the gas injection holes. The results show that, when the total mass flow rate is constant, the mixing effect becomes better as the dispersion degree of gas injection increases and the mass flow rate of each hole decreases. For this study, the 5-hole scheme has the best performance, and when the total mass flow rate and the number of injection holes are fixed, a smaller mass flow rate of gas injected toward the outlet of each air inlet is more conducive to better mixing and combustion effects. When the total mass flow rate is constant and the shape of the injection holes are complete circles, increasing the number of holes is more effective than decreasing the mass flow rate of gas injected toward the outlet of the air inlets in improving combustion efficiency.

Valence subbands profile regulation in AlGaN quantum well based on k·p theory

The profiles for the valence subbands of an AlGaN-based quantum well (QW) is investigated by considering quantum confinement effect (QCE) and strain through the k · p theory. We have found that to increase the QCE and the compressive strain would rise the relative position of the heavy hole (HH) subband to the crystal field splitting hole (CH) subband in the valence band of the QW. However, although the variation trend of the relative valance subbands position is similar, the underlying mechanisms of the modulation by the QCE and strain are not the same. In addition, we have found that if the energy level between the HH and the CH subbands is close at a certain k t point, the subband anti-crossing effect of the QW will enhance their coupling level, causing dipole moments from the conduction subbands to these valence subbands transformation between each other. These results can provide important basis for the active region design of some AlGaN-based short wavelength, high carrier injection, or monolithic integration optoelectronic devices.

Topology Optimization of Low-Loss Z-Bend 2D Photonic Crystal Waveguide

In this article, we design a low-loss, high-bandwidth Z-bend photonic silicon crystal waveguide bending in a triangular lattice through topology optimization. Based on the topological optimization method, we change the relative position of air holes in the global scope to maximize the transmittance and bandwidth of the waveguide. The simulation results indicate that the transmission characteristics can be effectively improved with our method. After the optimization, the loss of the waveguide can be reduced to −5 dB and the bandwidth can increase to 160 nm. Our research has great significance for further optimizing the propagation of light in photonic crystals.

Tuning geometry distortion of pyrochlore RE2Zr1.95Ni0.05O7+δ anodes with rich oxygen vacancies for ammonia-fed solid oxide fuel cell

Pyrochlore oxide A2B2O7 is a potential anode catalyst of ammonia-fed solid oxide fuel cell (SOFC) due to its unique and open structure that can make some oxygen ions flow to occupy the hole position to form Frankel defect. Herein, various rare-earth ions with different radius are selected as the A site to construct defective pyrochlore oxide RE2Zr1.95Ni0.05O7+δ (REZN, RE = La, Pr, Nd, Sm, Gd, LZN/PZN/NZN/SZN/GZN) to gain insights into oxygen vacancies that can be the diffusion and adsorption active site for ammonia. In the n-type semiconductor REZN, the degree of crystal ordering decreases with the decrease of the radius of rare-earth RE3+ ions. Among them, GZN exhibits the most negative conduction band and the smallest band gap, making it easier to overcome the energy potential barrier and facilitate the movement of carriers. As a result, the conductivity of GZN is about 25 times higher than that of LZN. The average TEC value of GZN is 10.40 × 10-6 K−1, which matches that of electrolyte YSZ (10.50 × 10-6 K−1). The maximum power density of ammonia-fed SOFC supported by YSZ electrolyte based on GZN anode is 128.63 mW·cm−2 at 800 °C, which is 2.3 times higher than that of NiO-based SOFC. The single cell based on GZN anode can be run continuously for 100 h at 800 °C without significant degradation. The preliminary results suggest that GZN oxide is promising to be a candidate catalyst for ammonia-fed SOFC anode.

A visual positioning method for wedge support robot based on Pruned-Ghost-YOLOv3

The wedge support robot is the core module of the intelligent dismantling equipment for the bolster spring and wedge of railroad wagon. In this paper, to address the problem of accurate positioning of bolster hole with abnormal geometry and large error in the complex background, a light-weight object detection model is proposed based on GhostNet and model pruning algorithm: Pruned-Ghost-YOLOv3. The proposed models and the original YOLOv3 model are trained and evaluated on the bolster hole custom dataset. The results show that the improved Pruned- Ghost-YOLOv3 model is smaller, has fewer parameters and is faster compared to the original YOLOv3 model. To meet the requirements of operational efficiency and reliability, a precise positioning algorithm based on the bounding box of the bolster hole and an indirect positioning process are proposed in this paper. The comparative experiments of bolster hole positioning and wedge support are conducted on the wedge support robot. The experimental results show that the proposed Pruned-Ghost-YOLOv3 model can meet the requirements of rapid detection and positioning of the bolster holes, and the proposed precise positioning algorithm and robot positioning process have high accuracy and reliability. The research results are successfully applied to the development of a railroad wagon wedge support robot, and it has a good reference value for the development of the intelligent positioning system of heterogeneous workpiece operation robots in the complex background of related industries.

First-Principles Study of the Quasi-Particle and Excitonic Effect in o-BC2N: The GW + BSE Study

Ternary boron-carbon-nitride compounds are the hardest, chemically stable, and most applicable semiconductors in optoelectronic devices. We investigate the quasi-particle and excitonic properties of type II o-BC2N using many-body perturbation theory (MBPT). The state-of-the-art GW and BSE methods were used to determine the accurate band gap and excited-state characteristics of this material. We simulate the convergence test and structural optimization in DFT, which is the starting point for the GW calculation. We also compute the convergence test of the parameters in GW and BSE. As a result, the bandgap of our system is found to be 2.31 eV and 1.95 eV using the GW approximation and DFT-PBE, respectively. Since the valence and conduction band edges are located at different Brillouin zones, we decide that o-BC2N is an indirect bandgap semiconductor. In addition, by applying the scissor operator, we corrected the quasi-particle bandgap, which shows almost the same result as the GW approximation. Furthermore, using the BSE algorithm, we calculate the optical bandgap of type II o-BC2N to be 4.0 eV with the excitonic effect and 4.4 eV without the excitonic effect. The highest peaks of the imaginary dielectric function with the excitonic effect shift to a lower energy level at 11 eV than without the excitonic effect at 13.5 eV. The electron charge distribution is computed by fixing the hole position. Finally, we suggest that type II o-BC2N is promising for the application of optoelectronic semiconductors.

Improvement in hole-pose error for aerospace drilling applications based on Hermite surface reconstruction and manifold error similarity

Hole position accuracy and perpendicularity are significant factors in aerospace drilling. This study presents a novel compensation method with reference holes to reduce the hole position error and initial normal deviation for automated drilling systems. The hole-pose error and related generalized addition and subtraction methods are first defined using quaternions. Subsequently, approaches for accurately measuring the pose of the reference hole and calibrating the coordinate system are proposed. On this basis, the position error and initial normal error are estimated by bilinear interpolation based on the error similarity on the two-dimensional manifold, where the manifold coordinates are obtained by Hermite surface reconstruction. Subsequently, the hole-pose error is compensated for by generalized addition. For the initial normal modification, a compensation strategy utilizing the data of processed adjacent holes for interpolation was adopted. In addition, for situations in which it is inconvenient to arrange real reference holes on the product, a compensation approach employing virtual reference holes was designed. Finally, simulations and experiments are conducted, and the results demonstrate that the position error and initial normal deviation are effectively reduced by at least 42.25% and 74.68% with the proposed method, which further ensures that the indicators meet the requirements of aerospace drilling.

Deep Imitation Learning with Pseudo-haptics Module for Peg-in-hole with Hole Position Uncertainty

Peg-in-hole is a task of product assembly. Robots insert the component (called “peg”) into the hole. In this paper, we tackle peg-in-hole with an uncertainty of hole position. Previous works search hole positions to insert pegs into uncertain holes. However, these methods have problems: annotation cost, positional accuracy, and long search time. Therefore, we use imitation learning (IL) which teaches robots through human teleoperation. IL provides the following benefits: lower annotation costs, rough visual servo, and an ability to find accurate hole positions by trial and error of insertion. However, current image-based IL cannot teach force perception to robots without a haptic feedback device. To solve this problem, we focused on pseudo-haptics. Pseudo-haptics is a force presentation method that does not require a mechanical feedback device. We propose a “Pseudo-haptics Module (PHM)” to feel the robot's pseudo-haptics. The module is designed from the process by which humans perceive pseudo-haptics. Our method with PHM is 7.7% higher peg-in-hole success than simple CNN.

Parallel parametric analysis approach based on an s-version FEM for fracture mechanics analysis in designing hole positions

This study proposes a parallel parametric analysis approach, in which parametric analysis for a local shape, such as a hole, is automated and parallelized. For the automation, the present approach is based on an s-version FEM, namely, the coupling-matrix-free iterative s-version FEM. In this method, the hole can be detached from the mesh of the global structure. This feature overcomes a difficulty in generating a mesh with a hole, particularly together with a crack for fracture mechanics analysis. Moreover, the parallelization is implemented by Message Passing Interface (MPI). In the present approach, a large number of analyses for different hole positions are performed in parallel. In each analysis, the hole position is changed using the s-version FEM. Then, this approach was applied to numerical examples of stationary crack problems, namely, a plate with an edge crack and a V-bending die with a circular surface crack. Both examples had a hole, the position of which was the parameter of the parametric analysis. In each numerical example, changes in stress intensity factor of the crack for different hole positions were investigated. It was numerically demonstrated that some hole positions decreased the stress intensity factor of the crack. Moreover, our approach achieved high speedup and parallel efficiency in a strong scaling test.

The Loss and Efficiency Analysis and Research of Interior Permanent Magnet Synchronous Motors for Traction Applications

An IPMSM with I2V type rotor topology structure is proposed, its loss, efficiency and torque are analyzed and compared with V and IV type. Firstly, the optimized rotor topology structures are used to analyze the no-load air-gap flux density waveform and harmonic contents of the IPMSM. The results show that the THD of the no-load air-gap flux density with the I2V type is the smallest and the sinusoidal degree of the waveform is the highest. Secondly, the loss of the IPMSM with optimized rotor topology structures are analyzed and compared. Compared with the other two rotors, the results show that the iron loss of the IPMSM with the I2V type is the smallest. The iron loss of the IPMSM with I2V type is significantly less than that of the other two rotors especially under the deep flux weakening conditions. The output torque of the IPMSM under different current angles, current densities and speed are analyzed and compared. The results show that the torque performance of the IPMSM with I2V type is better than the other two rotors. this paper proposes a simple and effective method to optimize the position and diameter of the magnetic isolation holes by establishing a parameterized model. The results show that the torque ripple and cogging torque with the further optimized I2V type rotor topology structure are greatly reduced, the iron loss and magnet loss are also effectively reduced. Finally, the von Mises stress and the total displacement of the rotor deformation of the IPMSM with the further optimized I2V type under different working conditions are verified by finite element analysis. The results show that the rotor will not rupture, the displacement is small enough to avoid the touch between stator and rotor.

Microstates of position and momentum result in gravitational entropy

Measurements of a black hole’s position are limited in four different ways: Absorption of short-wavelength photons by the black hole, gravitational lensing’s interference with geometric diffraction, gravitational redshift decreasing the resolution of interactions close to the event horizon, and the relatively long wavelength of Hawking radiation. These limitations mean that a black hole cannot be localized more precisely than its Schwarzschild radius. Limitations on measuring mass and velocity mean that the position and momentum of a black hole cannot be simultaneously known more precisely than 2 h rs/lP , a value more restrictive than the Heisenberg uncertainty principle. Hidden information about a black hole’s position and momentum results in many possible microstates that are indistinguishable to an observer. One way to interpret the physical meaning of Bekenstein‐Hawking entropy is as a measure of the number of these microstates. This interpretation allows entropy to be generalized to objects in any gravitational field, because gravitational redshift increases uncertainty about position and momentum for objects in all gravitational fields, not just those of black holes.

Numerical decoupling of the effect of internal cooling and external film cooling on overall cooling effectiveness

In modern aero-engine turbine blades, the coolant flows from the internal cooling channel and out through the film hole, forming a coolant coverage over the blade surface to isolate the high-temperature gas. Essentially, the cooling system can be divided into parts with internal cooling and external film cooling; in particular, external film cooling includes coolant coverage (film cooling) and bore cooling (cooling within the film hole). Accordingly, it is important to quantitatively analyze the effects of these three cooling parts (internal, bore, and film cooling) on the overall cooling effectiveness, which can help improve the design of turbine blades. To this end, in this study, the numerical decoupling method was used to investigate the relationship between the overall cooling effectiveness of two plate cooling structures and three cooling parts. Considering blowing ratios of 0.25, 0.5, 1, and 1.5, it was found that the blowing ratio and film hole position have considerable impacts on the overall cooling effectiveness of a smooth model; however, the overall cooling effectiveness of an impingement-effusion model was deemed insensitive to the film hole position. Furthermore, in the case of a small blowing ratio (M = 0.25), the internal heat transfer enhancement caused by impinging jets was less than that due to increased coolant flow rates. In the regions located upstream of each film hole exit, bore cooling had significant effects on the overall cooling effectiveness; particularly, these effects were more pronounced in the smooth model. Moreover, for a blowing ratio of 0.25, film cooling was dominant across all the cooling parts. With an increase in the blowing ratio, the influence of bore cooling grew rapidly, gradually replacing film cooling. Additionally, as the blowing ratio increased to 1.5, the effect of internal cooling exceeded that of film cooling. This work and its results are expected to serve as guidance for the design of turbine blade cooling structures.

Magnetic properties in atomic Co manipulated graphitic carbon nitride

Since discovery of graphene which has unique electronic properties, much effort has been paid to invoke other properties like optical and magnetic for different applications. Considering spintronics applications, it is wise to develop magnetic properties in 2D materials as most of them are diamagnetic and have superior electronic properties. Previously, we have manipulated transition metal atoms (TM) on graphene surface and observed very interesting magnetic properties. But the limitation of graphene is to manipulate single TM atom on the hole position in carbon honeycomb structure. Therefore, to manipulate multi atoms on the hole position for investigating the effect of interaction between the TM atoms as well as with the carbon network structure, in the present work, we have manipulated single to multi atoms (Cobalt atoms) in the large cavity of graphitic carbon nitride (g-C3N4). We have controlled the number of atoms in the cavity by varying the concentration of ‘Co’ atoms. We have synthesized three samples S1, S2 and S3 with lower, medium and highest concentrations of ‘Co’ atoms, respectively. For lower concentration one atom/cavity is more probable. In case of medium concentration most of the cavities are filled by single atom while few cavities are filled by multi atoms and for the highest concentration most of the cavities are filled by multi atoms. It is seen that all the samples show ferromagnetism at low temperature region but at higher temperature region either paramagnetic or antiferromagtic behaviour is obtained depending upon the concentration of ‘Co’ atoms. The long range ordering is explained on the basis of the interaction between the magnetic moments generated in g-C3N4 lattice due to charge transfer from ‘Co’ atom to g-C3N4 lattice via π-electrons. We believe that TM atom embedded g-C3N4 having controlled magnetic properties could be a promising material for spintronics applications.

Energy absorption characteristics of E-glass/epoxy over-wrapped aluminum pipes with induced holes: an experimental research

The effect of inducing circular holes into aluminum wrapped with glass/epoxy (Al/GFRP) pipes was investigated. Intact and holed specimens were evaluated in quasi-static axial compression after being constructed using the wet wrapping procedure. The effect of the induced holes' parameters i.e., hole diameter (d), number of holes (n), the hole position to specimen height ratio (L/H), on the crashworthiness of Al/GFRP structures was investigated. Results indicated that the existence of the cutouts visibly affects the values of crushing parameters. Increasing (d) remarkably reduces the total absorbed energy (U) and enhances the crushing force efficiency (CFE) of Al/GFRP pipes. Introducing two holes in two opposite faces with keeping their location constant reduces initial peak crush force {(mathrm{F}}_{mathrm{ip}}), mean crush force {(mathrm{F}}_{mathrm{m}}), and U of Al/GFRP pipes but increases CFE. As the hole location goes to the lower edge of the pipe i.e., L/H increases, U obviously increases. The specimens with 4 mm holes in one side at medium height and specimens with 12 mm holes on one side at L/H = 0.8 had the best crushing parameters, respectively. The adequate design of the induced cutouts in thin-walled constructions is valuable to enhance the crashworthy performance of engineering structures.

Importance of core and shell sizes in the localization of the electron and hole in the formation of type I or type II excitons in spherical CdSe/ZnTe and CdSe/CdTe quantum dots.

Semiconductor core/shell quantum dots represent a promising class of nanostructure that can provide new techniques of control for performing the electronic and optical properties. Through each combination formed by the core and the shell radii and the confinement effect, the trapped charge carries behave differently, which obviously has a direct effect on the semiconductor properties. Studying the behavior of charge carriers is one of the most important steps in understanding the semiconductor performance when it undergoes certain conditions, which inevitably can offer other benefits for various applications. The electron and hole localizations strongly depend on core and shell sizes, but determining these limit sizes has not been sufficiently discussed in the literature. This paper gives a detailed theoretical study describing the three cases of electron and hole positions in two different type II core/shell quantum dots, CdSe/ZnTe and CdSe/CdTe considering the core and shell sizes. Our numerical calculations show that two significant critical radii of the core allow to switch between the exciton type I and type II quasi-particle. As a function of the shell thickness, the ground state energy of the electron is found to be higher when the core radius is small; contrariwise, the hole ground state energy remains smaller. Afterward, these specific variations influence the ground state binding energy of the correlated electron–hole quasi-particle (exciton), leading to a particular behavior of this energy as a function of the core and shell sizes.