Single Angle Research Articles

Steering Geometry of Remote Control Agricultural Vehicle

For any vehicle, steering mechanism is important one, in this research discuss importance of steering mechanism, what kind of steering mechanism used. For designing Unmanned remote control agricultural vehicle is rear wheel drive vehicle and front wheel is used for steer or turn the vehicle, but challenge for designing this type of vehicle is that unmanned remote control agricultural vehicle is not only working in flat road surface but it’s also used in agricultural field also. Another challenge was to working of steering system very fluently and reliable for farmer. The maximum steering effort was found 101.53 N for single wheel and angle for inner and outer wheel was 45.24° and 30.74° respectively. We have also found the turning radius of vehicle was 1490 mm.

Technological aspects of grinding the side surfaces (relieving) of the teeth gear-cutting worm hobs

Contact line geometry at relieving of tooth flanks of gear cutting hobs and functional relations for calculation of relieving machine setting parameters for achieving the required accuracy of the tooth profile of the generating rack are determined. They include the setting angle of the grinding wheel axis and profiles of grinding wheel active surfaces for each of the tooth flanks. A method of calculating the single setting angle of the grinding wheel axis for both tooth flanks of the hob is developed.

Stability of equal-leg angle section braces with torsional restraints

Cross bracing using the single leg angle sections are connected on both sides at the joints, affecting the stability capacity of the cross bracing because of the torque. The study on the stability capacity of equal-leg angle sections with the effects of torsional restraints at joints was insufficient. Additionally, there is no clear guidance from relevant design codes. In this study, an end constraint was designed to simulate the effect of torsional restraints for the angle sections. A total of 105 specimens of angle sections, divided into three kinds of pieces (A, B, C), were tested under three boundary conditions. Additionally, Finite Element Method modeling to study the effects of end constraint was parallelly conducted. Class B specimens had the worst stability. When the slenderness ratio is <120, the stability capacity of Class C specimens is larger. When the slenderness ratio is larger than 120, Class A specimens have better stability. The stability capacity of the equal-leg angle sections is positively related to the stiffness of the end constraint, when the stiffness is less than or equal to 200 kN•m/θ, the change of the stability capacity appears more dramatic, when the stiffness exceeds 200 kN•m/θ, the increase becomes slower. The effect of the slenderness ratio and the ratio of the torsional stiffness at nodes to the bending stiffness of columns were quantified through the stability capacities obtained from the experiment and FEMs to propose a modified method for effective length coefficients, which could optimize transmission tower design.

A partially buckling-restrained brace with T-shaped double core for seismic retrofit: Experimental study, numerical analysis, and local stability design

A novel partially buckling-restrained brace with T-shaped double core (PTBRB) was proposed for the seismic retrofit of existing T-shaped steel members consisting of two separated steel angles. The retrofitting scheme primarily comprises two external steel angles and one cover plate which are bolted to serve as restrainer to prevent global buckling of existing T-shaped steel members. Cyclic tests were performed to verify the effectiveness of the retrofitting scheme and evaluate the PTBRB performance as seismic fuse. The results showed that adoption of the retrofitting scheme had negligible influence on the elastic stiffness of the T-shaped steel members, but their axial compression force capacity was increased by 60 %. The PTBRB specimens exhibited full hysteresis before failure, with the best ductility coefficient and cumulative plastic deformation capacity of 11.83 and 523, respectively. The controlled buckling mode of the PTBRB was identified by numerical analysis, and the results showed that the local buckling of a single steel angle member was responsible for the stiffness degradation of the PTBRB hysteresis. Theoretical local stability analysis of PTBRB was carried out according to Bleich’s theory and Lundquist’s theory and the test results confirm that the Bleich’s theory is more reliable for predicting the theoretical inelastic critical load. The maximum compression capacity of the PTBRB corresponding to the local stability requirement of a single steel angle member is proposed to achieve the seismic fuse function, which is further validated by numerical analysis.

SD-OCT assessment and visual field changes 1 year or more after a single episode of unilateral acute primary angle closure

Objective: To evaluate structural and visual field (VF) changes after ≥1 year of a single acute primary angle closure (APAC) attack using spectral-domain optical coherence tomography (SD-OCT) and standard automated perimetry (SAP). Methods: Patients with a single unilateral APAC crisis at least 1 year ago were included consecutively from 2013 to 2016. Contralateral eye was used as control. All patients underwent ophthalmic examination, RNFL imaging by SD-OCT, and SAP using Octopus 1-2-3. Results: 54 eyes (27 patients) were enrolled. [...]

Contribution of modern rotor profiles to energy efficiency of screw compressors

Screw rotors are the heart of screw compressors. And the energy efficiency of industrial machines is a matter of tremendous significance now more than ever. Historically, rotor profile developments have played a key role in making screw compressors energy efficient and commercially viable. Further attention to manufacturing aspects of rotor profiles and the invention of the rack generated rotor profiles led to rotor profiles having good manufacturability. The principles of rotor profile generation and manufacturing are available in open literature since 1960’s. But more and more literature on rotor profiling has been published since then. Modern screw rotor profiles (patented close to and in the 21st century) have all the principles of a good profile incorporated in their design. Hence the industry and profile designers at large are aware of the increasing difficulty to further make the twin screw compressor rotor profiles more energy efficient. This paper tries to quantify the contribution of rotor profile to energy efficiency of a typical twin screw compressor by comparing the most recent (hence modern) screw compressor rotor profiles. In order to fairly compare different rotor profiles, all are retrofitted to a single size, lobe combination, rotor length, and helix angle. Only the curves constituting the profile, as dictated in the patent documents of the respective profiles, have been changed. Tools such as SCORPATH and SCORG have been used to do the geometric and thermodynamic calculations on the profiles. Keeping the working conditions same for all the retrofitted but different profiles, a comparison has been made. This comparison sheds some light on how much is the energy efficiency of a particular twin screw compressor influenced by a mere change of profile. This analysis can be further extended to establish reasonable targets for twin screw compressor manufacturers to improve energy efficiency of their machines via improving their rotor profiles. This remains the future scope of this work.

Relative Sagittal Alignment of the Medial and Lateral Articular Surfaces of the Tibial Plateau Using Radiographic Parameters: A Radiographic Cadaveric Study.

To characterize anatomic slope (sagittal alignment) of medial and lateral articular surfaces of the tibial plateau using x-ray and computed tomography (CT). Fluoroscopy was used to acquire "perfect" anteroposterior (AP) images of 8 cadaveric knees by tilting a C-arm through a 30-degree cranial/caudal arc in 0.5-degree increments. Five surgeons independently selected perfect AP images that most accurately profiled medial and lateral articular surfaces. Corresponding angles were used to define tangent subchondral structures on sagittal CT that were considered as dominant bony landmarks in a protocol to determine tibial slope on sagittal CT in 46 additional cadaveric knees. Mean perfect C-arm AP angles were 4.2 degrees ± 2.6 degrees posterior for the medial plateau and 5.0 degrees ± 3.8 degrees posterior for the lateral plateau. It was noted that images acquired within a range of angles (medial range, 1.8 degrees ± 0.7 degrees; lateral range, 3.9 degrees ± 3.8 degrees) rather than a single angle adequately profiled each compartment. Using the CT protocol, mean medial slope (5.2 degrees ± 2.3 degrees posterior; range, 0.9-11.5 degrees) was less than lateral slope (7.5 degrees ± 3.0 degrees posterior; range 0.6-12.5 degrees; P < 0.001) in 54 knees. The difference between medial and lateral slopes in any individual specimen ranged from 3.1 degree more medially to 6.8 degrees more laterally. No differences were noted between right and left knees in paired specimens. On average, tibial slope in the lateral plateau is slightly greater than that in the medial plateau, and variation exists between compartments across patients. Because tibial slope is similar between contralateral limbs, evaluating slope on the uninjured side can provide a template for sagittal plane reduction of tibial plateau fractures.

Biometric facial identification using attention module optimized YOLOv4 for sheep

Automatic identification of individual animals is an important step in modern farm breeding. Current best practice involves the use of RFID tags which are time-consuming for the farmer and distressing for the animal. To overcome this, we developed a sheep face recognition model through deep learning method, and realized individual identity recognition through sheep facial images. Considering the unstable recognition effect caused by the single angle of sheep facial images in the training set, we collected five kinds of sheep facial images to extract more robust facial features. Data from 67 Small-tailed Han breed sheep, aged one to two years, from two different groups of sheep, were collected over a period of one month. To recognize the identity of sheep, the YOLOv4 model was applied, and the convolutional block attention module (CBAM) was further introduced to enhance the feature extraction ability of the model. We compared the improved model with different object detection models, and the results showed that the mAP@0.5 of group1 and group2 were 91.58% and 90.61% respectively, which proved that the improved model had good recognition performance. The findings of this research could provide technical support for biometric facial recognition of sheep.

Estimating seismic response to bidirectional excitation per unidirectional analysis: A reevaluation for motions with fling-step using SDOF systems

Within the context of near-fault motions with fling-step signature, the present paper reevaluates the applicability of a straightforward alternative to estimate the response to bidirectional shaking per unidirectional analysis. The method originally evolved for motions with forward-directivity, uses unidirectional analysis in a single incidence angle. The performance of the method is examined using reinforced concrete (RC) bridge piers as the representative single-degree-of-freedom (SDOF) oscillators. Synthetic fling has been introduced to two horizontal components of processed (base-line corrected and filtered) strong motions. It has been shown that the response to bidirectional excitation can be closely estimated by means of a unidirectional analysis using the ground motion components rotated to the most preferred orientation. Existence of the least preferred orientation in which the unidirectional analysis results in the maximum difference from the bidirectional analysis appears to reinforce the development. For a ground motion pair, these orientations can be identified in advance through characteristic ground motion parameters, viz., energetic length and characteristic intensity for peak and cumulative demand, respectively. The usefulness of the said orientations to estimate the Park-Ang damage index is also established. The efficacy of the simple methodology has also been demonstrated through fragility analysis. The straightforward method can hence be used in the near-fault regime regardless of the ground motion characteristics.

An investigation of shear failure in welded channel and angle brace members

Shear yielding (SY) and shear rupture (SR) are base metal failure modes in welded connections of brace members to gusset plates. Although gusset plated connections have been extensively investigated in the past nonetheless, the shear failure limit states of welded brace members have not received significant attention. This paper aims to shed some light on the shear failure mechanism and strength of welded brace members consisting of single and double channels and angles. For this purpose, a nonlinear finite element (FE) model with ductile damage simulation is developed and validated against the authors’ experiments and other available test results. Then an extensive parametric study using 432 models is performed. The yield and ultimate failure loads of the members have been determined. The results show that the code-specified approach to predict the shear strength of members is very conservative and does not consider the existing tensile strength contribution of the members. In addition, the commonly assumed failure patterns are inaccurate. FE findings show that the SY limit state always occurs prior to SR with about 50% less strength. Moreover, it is found that the yielding mechanism in the SY limit state is limited to the connection region. The shear failure behavior under compression loading and the effects of connection geometry have also been examined. Based on extensive FE analyses, it is recommended to ignore the SY limit check in designing brace members. Moreover, a modification is proposed to the conventional SR formula using a block shear (BS) framework that includes tensile areas to predict the member’s strength more accurately. Application of the proposed recommendations in the seismic design of brace-to-gusset connections results in a more economical connection.

Pore-scale phenomena in carbon geological storage (Saline aquifers—Mineralization—Depleted oil reservoirs)

The injection of CO2 into geological formations triggers inherently coupled thermo-hydro-chemo-mechanical processes. The reservoir pressure and temperature determine the CO2 density, the CO2-water interfacial tension, and the solubility of CO2 in water (hindered by salts and competing gases). The CO2-water interface experiences marked pinning onto mineral surfaces, and contact angles can range from the asymptotic advancing to receding values, in contrast to the single contact angle predicted by Young’s equation. CO2 dissolves in water to form carbonic acid and the acidified water dissolves minerals; mineral dissolution enhances porosity and permeability, triggers settlement, may couple with advection to form “wormholes”, produces stress changes and may cause block sliding and shear bands. Convective currents can emerge beneath the CO2 plume and sustain CO2 and mineral dissolution processes. On the other hand, mineralization is a self-homogenizing process in advective regimes. The crystallization pressure can exceed the tensile capacity of the host rock and create new surfaces or form grain-displacive lenses. Within the rock matrix, coupled reactive-diffusion-precipitation results in periodic precipitation bands. Adequate seal rocks for CO2 geological storage must be able to sustain the excess capillary pressure in the buoyant CO2 plume without experiencing open-mode discontinuities or weakening physico-chemical interactions. CO2 injection into depleted oil reservoirs benefits from time-proven seals; in addition, CO2 can mobilize residual oil to simultaneously recover additional oil through oil swelling, ganglia destabilization, the reduction in oil viscosity and even miscible displacement. Rapid CO2 depressurization near the injection well causes cooling under most anticipated reservoir conditions; cooling can trigger hydrate and ice formation, and reduce permeability. In some cases, effective stress changes associated with the injection pressure and cooling thermoelasticity can reactivate fractures. All forms of carbon geological storage will require large reservoir volumes to hold a meaningful fraction of the CO2 that will be emitted during the energy transition.

Effect of propioceptive and strength exercises on calf muscle endurance, balance and ankle angle applied: Latin Dancers

The aim of the study was to examine the effect of proprioceptive and strength exercises applied in addition to dance exercises on the endurance of calf muscles, balance and ankle angles. Participants were randomly divided into two groups as Training Group (n=14; 7 males, 7 females) and Control Group (n=13; 7 males, 6 females). The training group performed a 12-week training programme that included proprioceptive and strength exercises twice a week, just before dance training. Anthropometric measures, static-dynamic balance tests, single heel rise test and 3D kinematic tests were conducted. When the groups were compared, significant changes were observed in the double leg dynamic balance values of the training group, right leg dynamic balance values of the control group, and left leg dynamic balance values of both groups (p&lt;0.05). When ankle angles were compared, the first single heel rise and angle of movement of the last single heel rise values of the training group differed significantly (p&lt;0.05). The balance performance and calf muscle endurance of the dancers can be improved with proprioceptive and strength training, which can contribute positively to movements during the dance.

Magic angles in twisted bilayer graphene near commensuration: Towards a hypermagic regime

The Bistritzer-MacDonald continuum model (BM model) describes the low-energy moir\'e bands for twisted bilayer graphene (TBG) at small twist angles. We derive a generalized continuum model for TBG near any commensurate twist angle, which is characterized by complex interlayer hoppings at commensurate $AA$ stackings (rather than the real hoppings in the BM model), a real interlayer hopping at commensurate $AB/BA$ stackings, and a global energy shift. The complex phases of the $AA$ stacking hoppings and the twist angle together define a single angle parameter $\phi_0$. We compute the model parameters for the first six distinct commensurate TBG configurations, among which the $38.2^\circ$ configuration may be within experimentally observable energy scales. We identify the first magic angle for any $\phi_0$ at a condition similar to that of the BM model. At this angle, the lowest two moir\'e bands at charge neutrality become flat except near the $\boldsymbol\Gamma_M$ point and retain fragile topology but lose particle-hole symmetry. We further identify a hypermagic parameter regime centered at $\phi_0 = \pm\pi/2$ where many moir\'e bands around charge neutrality (often $8$ or more) become flat simultaneously. Many of these flat bands resemble those in the kagome lattice and $p_x$, $p_y$ 2-orbital honeycomb lattice tight-binding models.

Methods for Determining the Infrared Complex Refractive Indices n(λ) and k(λ) from Organic Solid Powders: Comparison of a Sucrose Single Crystal and a Pressed Pellet

There exists a need to measure optical constants n and k for many materials, especially organic solids in the infrared spectral region, but at present, there are only two established methods for making such measurements: single-angle (SA) reflectance and infrared spectroscopic ellipsometry (IRSE). The former derives the n/k vectors via measurement of the change in the amplitude of light reflected from the sample and then uses the Kramers–Kronig transform, while the latter measures the change in polarization of the reflected light from the sample to derive n/k. Here we make a direct comparison between the n/k vectors derived from SA measurements of a sucrose single crystal and the n/k values obtained after the crystal had been crushed, ground to powder, and pressed into a pellet form. The pellet was measured not only by SA but also via the IRSE method, and we found that pressing specular-quality pellets was critical, especially for the SA data. The n/k values of this typical organic molecule all agree to within 0.04 root-mean-square error, confirming that a pressed pellet can be used instead of a crystal to derive the intrinsic n/k vectors. This result is important for the many organic materials that, unlike sugar, do not have centimeter-sized crystals readily available.

Multi-network collaborative lift-drag ratio prediction and airfoil optimization based on residual network and generative adversarial network.

As compared with the computational fluid dynamics(CFD), the airfoil optimization based on deep learning significantly reduces the computational cost. In the airfoil optimization based on deep learning, due to the uncertainty in the neural network, the optimization results deviate from the true value. In this work, a multi-network collaborative lift-to-drag ratio prediction model is constructed based on ResNet and penalty functions. Latin supersampling is used to select four angles of attack in the range of 2°–10° with significant uncertainty to limit the prediction error. Moreover, the random drift particle swarm optimization (RDPSO) algorithm is used to control the prediction error. The experimental results show that multi-network collaboration significantly reduces the error in the optimization results. As compared with the optimization based on a single network, the maximum error of multi-network coordination in single angle of attack optimization reduces by 16.0%. Consequently, this improves the reliability of airfoil optimization based on deep learning.

Novel light field imaging device with enhanced light collection for cold atom clouds

We present a light field imaging system that captures multiple views of an object with a single shot. The system is designed to maximize the total light collection by accepting a larger solid angle of light than a conventional lens with equivalent depth of field. This is achieved by populating a plane of virtual objects using mirrors and fully utilizing the available field of view and depth of field. Simulation results demonstrate that this design is capable of single-shot tomography of objects of size \U0001d4aa(1 mm3), reconstructing the 3-dimensional (3D) distribution and features not accessible from any single view angle in isolation. In particular, for atom clouds used in atom interferometry experiments, the system can reconstruct 3D fringe patterns with size \U0001d4aa(100 μm). We also demonstrate this system with a 3D-printed prototype. The prototype is used to take images of \U0001d4aa(1 mm3) sized objects, and 3D reconstruction algorithms running on a single-shot image successfully reconstruct \U0001d4aa(100 μm) internal features. The prototype also shows that the system can be built with 3D printing technology and hence can be deployed quickly and cost-effectively in experiments with needs for enhanced light collection or 3D reconstruction. Imaging of cold atom clouds in atom interferometry is a key application of this new type of imaging device where enhanced light collection, high depth of field, and 3D tomographic reconstruction can provide new handles to characterize the atom clouds.

Programmable VO2 metasurface for terahertz wave beam steering

SummaryProgrammable vanadium dioxide (VO2) metasurface is proposed at THz frequencies. The insulating and metallic states of VO2 can be switched via external electrical stimulation, resulting in the dynamical modulation of electromagnetic response. The voltages of different columns of the metasurface can be controlled by the field-programmable gate array, and thus the phase gradients are realized for THz beam steering. In 1-bit coding, we design periodic and nonperiodic 24 × 24 coding sequences, and achieve wide-angle beam scanning with the deflection angles from −60° to +60°. In 2-bit coding, we use two different meta-atoms to design 18 × 18 coding sequences. Compared with 1-bit coding, 2-bit coding has more degree of freedom to control the optical phase, and 3 dB diffraction efficiency is improved by generating a single deflection angle. The proposed programmable metasurfaces provide a promising platform for manipulating electromagnetic wave in 6G wireless communication.

Simulation research on macroscopic bond breakage on the rake face of cemented carbide inserts

The bond breakage on the rake face of cemented carbide inserts has a significant impact on the life of the insert. The problem of cemented carbide insert bonding damage is analyzed, and the main failure mode of cemented carbide insert is brittle fracture. Based on the extended finite element method (XFEM) and cohesive technology, and according to the stress state of cemented carbide insert in different cutting states and the position of adhesion layer, the actual boundary conditions are set in ABAQUS simulation environment. The three-dimensional macroscopic simulation model with crack structure and load-bearing capacity that meets the actual working conditions is established, and the influence of no cracks, single cracks at different angles, multiple cracks, and load on the peeling of the adhesion layer are analyzed. Regardless of whether it is in the state of no pre-crack or multiple cracks, the rake face is damaged when the adhesive layer is subjected to a shear load parallel to the rake face, which is similar to the experimental results. while in the single crack state, the position, angle and load direction of the crack do not show excessive sensitivity to the peeling of the adhesion layer, which provided a theoretical basis for revealing the essential reason for the bond failure effect of cemented carbide inserts.

Intrinsic Respiratory Gating for Simultaneous Multi-Mouse μCT Imaging to Assess Liver Tumors.

Small animal micro computed tomography (μCT) is an important tool in cancer research and is used to quantify liver and lung tumors. A type of cancer that is intensively investigated with μCT is hepatocellular carcinoma (HCC). μCT scans acquire projections from different angles of the gantry which rotates X-ray source and detector around the animal. Motion of the animal causes inconsistencies between the projections which lead to artifacts in the resulting image. This is problematic in HCC research, where respiratory motion affects the image quality by causing hypodense intensity at the liver edge and smearing out small structures such as tumors. Dealing with respiratory motion is particularly difficult in a high throughput setting when multiple mice are scanned together and projection removal by retrospective respiratory gating may compromise image quality and dose efficiency. In mice, inhalation anesthesia leads to a regular respiration with short gasps and long phases of negligible motion. Using this effect and an iterative reconstruction which can cope with missing angles, we discard the relatively few projections in which the gasping motion occurs. Moreover, since gated acquisition, i.e., acquiring multiple projections from a single gantry angle is not a requirement, this method can be applied to existing scans. We applied our method in a high throughput setting in which four mice with HCC tumors were scanned simultaneously in a multi-mouse bed. To establish a ground truth, we manually selected projections with visible respiratory motion. Our automated intrinsic breathing projection selection achieved an accordance of 97% with manual selection. We reconstructed volumetric images and demonstrated that our intrinsic gating method significantly reduces the hypodense depiction at the cranial liver edge and improves the detectability of small tumors. Furthermore, we show that projection removal in a four mice scan discards only 7.5% more projections than in a single-mouse setting, i.e., four mouse scanning does not substantially compromise dose efficiency or image quality. To the best of our knowledge, no comparable method that combines multi-mouse scans for high throughput, intrinsic respiratory gating, and an available iterative reconstruction has been described for liver tumor imaging before.

Effects of Performing Isometric Bench Press Training at Single Versus Multiple Joint Positions on Strength and Power Performance.

To compare the effects of isometric bench press performed at single (SIBP) and multiple (MIBP) joint angles on dynamic strength and overhead throwing performance. Sixteen male softball and baseball athletes performed overhead throwing, 1-repetition-maximum (1RM) bench press, and ballistic push-up during pretest and posttest. They were then randomly assigned to either SIBP or MIBP to undergo 12 strength training sessions. During the training, isometric bench press was performed at only 90° elbow angle for SIBP but at 60°, 90°, and 120° elbow angles for MIBP. A significant main time effect was observed for bench press 1RM (P = .003) and relative 1RM (P < .001). Similarly, a significant main time effect was observed for ballistic push-up peak power only (P = .037). There was no significant change in overhead throwing velocity in either group. There was also no significant difference in change in all measures between groups. However, a moderate effect in favor of MIBP was observed for change in ballistic push-up peak power (P = .180, g = 0.67). Based on the current findings, the inclusion of both SIBP and MIBP were equally beneficial to maximal strength development. However, performing MIBP had a greater effect on power development.