Intersection Angle Research Articles

Structure and Properties of TiNi Shape Memory Alloy after Quasi-Continuous Equal-Channel Angular Pressing in Various Aged States

The effect of quasi-continuous (QC) equal-channel angular pressing (ECAP) in various pre-aged states on the structure formation and mechanical and functional properties of a hyper-equiatomic titanium nickelide (TiNi) shape memory alloy is studied. QC ECAP with a channel intersection angle of 110° is carried out at a temperature of 450 °C after aging for 1 and 5 h for three passes. To investigate the obtained structure and properties, the following research methods are applied: transmission electron microscopy, XRD analysis, calorimetric study, tension and hardness tests, and a special technique for the determination of functional properties. QC ECAP allows for the considerable refinement of structural elements and results in obtaining a mixed fine-grade structure, with structural elements of average sizes of 92 nm after pre-aging for 1 h and 115 nm after pre-aging for 5 h. Pre-aging for 5 h before QC ECAP, in combination with QC ECAP and post-deformation aging at 430 °C for 1 h, provides the best combination of mechanical and functional properties: a dislocation yield stress of 1410 MPa, ultimate tensile strength of 1562 MPa, and total recoverable strain of 11.6%. These values are comparable with the best results obtained for titanium nickelide and expand opportunities for the application of smart shape memory devices.

Geometric triangulations and discrete Laplacians on manifolds: An update

This paper uses the technology of weighted triangulations to study discrete versions of the Laplacian on piecewise Euclidean manifolds. Given a collection of Euclidean simplices glued together along their boundary, a geometric structure on the Poincaré dual may be constructed by considering weights at the vertices. We show that this is equivalent to specifying sphere radii at vertices and generalized intersection angles at edges, or by specifying a certain way of dividing the edges. This geometric structure gives rise to a discrete Laplacian operator acting on functions on the vertices. We study these geometric structures in some detail, considering when dual volumes are nondegenerate, which corresponds to weighted Delaunay triangulations in dimension 2, and how one might find such nondegenerate weighted triangulations. Finally, we talk briefly about the possibilities of discrete Riemannian manifolds.

Pair interaction of intersecting dilatation and disclination defects

An elastic interaction of the intersecting dilatation and disclination defects located in an infinite linear isotropic media is investigated. The eigenstrain approach is employed to obtain the analytical expressions describing the pair interaction between intersecting dilatational lines and intersecting wedge disclinations. It is demonstrated that the interaction energy strongly depends on the intersection angle between the defects. The energy reaches the maximum value if the defect lines are coincided while the energy reaches the minimum value if the defect lines are orthogonal. Besides, it is shown that interaction energy of intersecting wedge disclinations strongly depends on the elastic properties of the media: the less thePoisson ratio, the less the energy. The obtained analytical results seem to be applicable for the theoretical analysis of the residual stress relaxation mechanisms in heterostructures with pentagonal symmetry such as icosahedral particles

Effect of boundary angle on aero-optical imaging deviation of the blunt-headed side-window vehicle.

This paper defines the intersection angle between the tangent plane at the boundary of aero-optical flow field and the body axis as the boundary angle and focuses on the influence of the boundary angle on the imaging deviation. This paper shows that the boundary angle of the aero-optical flow field is different at different flight conditions, which means the location of the zero value of imaging deviation is different. With the increase of the line of sight angle, the imaging deviation decreases first and then increases in the opposite direction. After the change of flight conditions, the boundary angle decreases with the increase of the compression of the flow field. The imaging deviation increases if the incident light is on the right side of the normal and decreases in the opposite direction.

Posterolateral musculo-fascial approach to the lumbar spine intervertebral discs: Anatomical study

Objective: assess an anatomical and topographic parameter of the wound channel formed when using the posterolateral muscular-fascial approach to determine the possibility of its clinical use for performing decompres-sive-stabilizing surgical interventions. Material and methods: on the material of 20 cadavers of both sexes with different body mass index (mean 25.1 ±2.9) aged 54 to 76 years (median 67.5 years), who died from diseases not associated with the pathology of the spine, was modeled the posterolateral muscular-fascial approach to the lumbar spine. During the research were studied wound length, wound depth, wound depth index, access zone and the angle of intersection of the wound edges and the surface of surgical instruments. Results: the average length of the surgical wound during the lateral muscular-fascial approach was 149.75±6.35 mm. The average wound depth was 116.75±8.85 mm. The average value of the index of the depth of the surgical wound with interfascial access is 77.96±5.04. The average area of the intervertebral disc available for removal was 71.2±2.8%. The length of the aperture in the fibrous ring averages 15.8±0.78 mm. The average value of the angle of intersection of the wound edge and the pedicle screw implantation trajectory was 3.15±1.25. Conclusion: the assessment of the anatomical and topographic parameters of the wound channel formed during the posterolateral muscular-fascial approach allows us to conclude that this surgical approach can be used to improve the functional outcomes of decompressive and stabilizing interventions in the lumbar spine.

Deformation lines in Arctic sea ice: intersection angle distribution and mechanical properties

Abstract. Despite its relevance for the Arctic climate and ecosystem, modeling sea-ice deformation, i.e., the opening, shearing, and ridging of sea ice, along linear kinematic features (LKFs) remains challenging, as the mechanical properties of sea ice are not yet fully understood. The intersection angles between LKFs provide valuable information on the internal mechanical properties, as they are linked to them. Currently, the LKFs emerging from sea-ice rheological models do not reproduce the observed LKF intersection angles, pointing to a gap in the model physics. We aim to obtain an intersection angle distribution (IAD) from observational data to serve as a reference for high-resolution sea-ice models and to infer the mechanical properties of the sea-ice cover. We use the sea-ice vorticity to discriminate between acute and obtuse LKF intersection angles within two sea-ice deformation datasets: the RADARSAT Geophysical Processor System (RGPS) and a new dataset from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) drift experiment. Acute angles dominate the IAD, with single peaks at 48∘±2 and 45∘±7. The IAD agrees well between both datasets, despite the difference in scale, time period, and geographical location. The divergence and shear rates of the LKFs also have the same distribution. The dilatancy angle (the ratio of shear and divergence) is not correlated with the intersection angle. Using the IAD, we infer two important mechanical properties of the sea ice: we found an internal angle of friction in sea ice of μI=0.66±0.02 and μI=0.75±0.05. The shape of the yield curve or the plastic potential derived from the observed IAD resembles a teardrop or a Mohr–Coulomb shape. With these new insights, sea-ice rheologies used in models can be adapted or redesigned to improve the representation of sea-ice deformation.

Single-image piecewise planar reconstruction of urban buildings based on geometric priors

Single-image 3D urban building reconstruction is an important and challenging topic in computer vision. However, it is a highly ill-posed problem due to the intrinsic geometrical ambiguity in a 3D space. To address the problem, this paper presents a novel single-image piecewise planar reconstruction method based on geometric priors. The proposed method utilizes geometric priors (e.g., plane orientation and intersection angles between planes) learned through convolutional neural networks to handle three challenging subtasks sequentially: (1) detecting planar regions with structure information (e.g., each component edge is associated with two planes intersecting at a specified angle); (2) inferring the planes corresponding to the planar regions progressively by taking full advantage of diverse constraints (e.g., structure and proximity constraints) based on geometric priors; and (3) globally optimizing the resulting planes under a unified framework that incorporates image cues and geometric priors. Experimental results on two public datasets released by CASIA and our own dataset demonstrate that the proposed method significantly outperforms five state-of-the-art methods (including two geometry-based methods and three learning-based methods) by an approximately 20 % margin in terms of accuracy. Code and data are available at https://github.com/three-dimensional-computer-vision/single-image-reconstruction.

Wire‐and‐Arc Additive Manufacturing for lattice steel structures: overview of the experimental characterization on dot‐by‐dot rods

AbstractWith the advent of a new arc‐based additive manufacturing (AM) process, referred to as Wire‐and‐Arc Additive Manufacturing (WAAM), the scale of the metal printed parts increased up to several meters, thus becoming suitable for large‐scale applications in marine, aerospace and construction sectors. However, specific considerations in terms of geometrical and mechanical properties ought to be made in order to effectively use the printed outcomes for structural engineering purposes. The introduction of the novel printing strategy referred to as “dot‐by‐dot”, consisting in successive drops of molten metal, enabled the use of WAAM to realize complex lattice structures, made by continuous grids of WAAM rods. Nevertheless, their proper design requires an accurate evaluation of the influence of the non‐negligible inherent geometrical irregularities on the mechanical response of the rods. Hence, extensive experimental work is needed in order to evaluate the mechanical response of “dot‐by‐dot” WAAM rods with geometrical imperfections. The present study focuses on the mechanical characterization of dot‐by‐dot WAAM‐produced 304L stainless steel intersected rods, constituting the basic units of grid and lattice structures. The mechanical response of the specimens is assessed through tensile experimental tests conducted on two‐ways planar nodes obtained from the intersection of two rods with different angles, hereafter also refereed to as crossed rods. The experimental results are then compared with tensile tests on single rods, to quantify the influence of the intersection angle in the structural response of the lattice structures.

Effect of geometry and hydraulic parameters on the bed morphology in a confluence using numerical approach

The confluence of rivers is an important phenomenon that is really vital for irrigation and water transmission networks. Investigation on bed morphology at the junction of two streams is of great importance. Flow complexity at confluences, as well as being at risks of rising water levels and flooding, interfering with the use of bridges, filling the inlets of the ponds and reducing the efficiency of water transport are resulted by this phenomenon. The purpose of this research is to investigate the effect of geometric and hydraulic parameters, such as junction angle, width ratio of two intersected canals, and Froude number on the bed morphology at intersection, using SSIIM2. Validation of the results of numerical model in terms of hydraulic and morphology parameters indicated good correlations coefficients of 0.9 and 0.68, respectively. In the next step, the effect of intersection angle (45, 60, 75, 90 and 105 degrees) on the scour depth was investigated. By decreasing the junction angle from 105° to 45°, the maximum scour depth reduced to about 96% and the scour hole dimensions were smaller and moved toward the confluence shore. Furthermore, the results showed that by increasing the width ratio from 0.5 to 1, and also, decreasing the Froude number ratio of tributary to main channel from 3 to 0.68, maximum scour depth decreased by 25% and 30%, respectively.

Experimental study on anisotropic unloading mechanical behavior of bedded sandstone

Sandstone is a kind of bedded rock mass commonly used in engineering. The deformation and strength of bedded sandstone impose some problems during excavation. In this study, triaxial unloading tests were conducted on rock specimens (considering seven different bedding angles (β)). The results revealed the following key points: (1) At a constant confining pressure, the elastic modulus was gradually increasing when the bedding angle increased. Furthermore, after initial decreasing, the deformation modulus was increased and had a U-shaped distribution. (2) During the unloading of the axial compression, the rate of axial strain variations was initially increased and then decreased while the bedding angle increased (it has exhibited an inverted U-shaped distribution). However, the peak strength, cohesion, and angle of internal friction of rock specimens showed an initial decreasing and then increasing trend. (3) During the loading and unloading stages, the confining pressure reduces the anisotropy of bedded rock masses. (4) In the triaxial unloading test, the failure of rock specimens can be classified into four modes. When there was a large intersection angle between the bedding plane and the unloading direction, failure developed at the bedding planes.

Collaborative optimization of intersectional angle and installation height of branched fin for ameliorating melting characteristics of lowly thermal conductive phase change materials (PCMs)

Energy storage systems based on phase change materials (PCMs) have become reliable methods to alleviate energy shortages and adjust energy structure. Optimizing fin structure parameters has a vital impact on improving the equivalent thermal conductivity of PCMs and enhancing thermal charging performance. In this numerical investigation, collaborative optimization of intersectional angle and installation height of branched fin on melting of organic PCMs have been systematically studied to coordinate transient thermal conduction and natural convective heat transfer thus ameliorating melting characteristics. Results clarify that optimizing intersectional angle between adjustable fin and horizontal direction can shorten total melting time by 9.39% and ameliorate the average heat transfer rate during melting by 11.07% compared to the case of 0o intersectional angle. These improvements are dependent of installation height of adjustable fin. Meanwhile, average heat transfer rate during melting induced by optimizing intersectional angle is enhanced by 2.77% compared with that caused by optimal orthogonal fins. Moreover, optimum intersectional angle is significantly depended on installation height. A linear correlation between optimum intersectional angle and installation height is obtained. The reliability and rationality of the correlation is confirmed. Effective guidelines for designing optimum branched fin to improve melting performance of organic PCMs are consequently acquired.

Mixed-Effects Zero-Inflated Negative Binomial Crash Predictive Models for Unsignalized Intersections along Two-Lane Highways with Minor Roads Operating with Very Low Traffic Volumes

Current and past investigations into road accidents have mainly focused on high-volume roads which have experienced a significant number of collisions. However, low-volume roads also record crash data which merit analysis to understand the causes of accidents and find potential countermeasures. This study focuses on unsignalized intersections linking major highways and minor stop-controlled local roads that operate with very low traffic volumes. In this scenario, an over-abundance of zero observations has to be accounted for. To address this issue, zero-inflated Poisson and negative binomial regression models have been calibrated and analyzed to find the geometric and operational factors which contribute most to the crash rate. Random effects have also been considered to account for unobserved heterogeneity inherent in the grouping of intersections within the database. The results indicate that the mixed-effect negative binomial model had the best prediction performance. Developing models for subgroups of crashes, for example, failure-to-yield and other types of crash, resulted in better prediction performance. The major road’s average annual daily traffic and the surface type (i.e., paved or unpaved) of minor road approaches had a significant effect on the frequency of all crash types. The type of intersection (three- or four-legs), the skew angle of intersection, deviation angle of near curves, and operating speed differences also had statistically significant effects on the frequency of crashes that do not include the failure-to-yield.

Numerical studies of the lymphatic uptake rate

Lymphatic uptake is essential for transporting nutrients, wastes, immune cells, and therapeutic proteins. Despite its importance, the literature lacks a quantitative analysis of the factors that affect lymphatic uptake, including interstitial pressure, downstream pressure, and tissue deformation. In this paper, we present a coupled model of a poroelastic tissue with initial lymphatics and quantify the impact of these factors on the rate of lymphatic uptake. Our results indicate that the lymphatic uptake increases with the amplitude of the oscillating downstream pressure when the amplitude exceeds a threshold. Additionally, the cross-sectional area of initial lymphatics increases with the volumetric strain of the tissue, while the interstitial pressure increases when the strain rate becomes negative. Therefore, the lymphatic uptake reaches its maximum when the tissue has positive volumetric strain while being compressed. We have also investigated the effect of intersection angles and positions of two initial lymphatics and concluded that they have minor impacts on lymphatic uptake. However, the lymphatic uptake per unit length of initial lymphatics decreases with their total length. These findings advance our understanding of lymphatic uptake and can guide the development of strategies to accelerate the transport of therapeutics.

Analysis of Displacement-Controlled Fretting Between Crossed Parabolic Cylinders in Elasto-plastic Contacts

Abstract In practice, it is difficult to avoid the axis angle deviation when some regular surfaces are in micro-sliding, such as gears, machined surfaces, etc. In order to better investigate the micro-motion contact characteristics, a crossed paraboloidal contact model under frictional condition is proposed to simulate both tangential displacement-controlled fretting and the evolution of the energy dissipation in a load cycle. By deriving the theoretical of the normal and tangential contact course of the model, the load-displacement curves during initial loading, unloading and reloading stage are presented. On this basis, the hysteresis curve is then obtained by integrating the closed area surrounded by load-displacement during unloading and reloading, which also means that the empirical formulation for micro-slip in a load cycle is constructed. This study also reveals the plastic yield phenomenon under pure normal loading and plastic shakedown behavior caused by cyclic reciprocating displacement loads. In addition, the research on the junction growth, the evolution of tangential load and hysteresis curve with different COFs under multiple-cycle load is also carried out. The implications of involved parameters, such as friction coefficient, axis intersection angle, normal load and so on, are discussed with respect to hysteresis curve shape and energy dissipation. The difference about hysteresis and energy dissipation curves between the paraboloidal contact model and other classic contact models is then presented. It is discovered by comparison with other models that the paraboloidal contact model presents a relatively high energy dissipation in a load cycle.

Estimation in jet deflection angle of deflector on the chutes

ABSTRACT Ski jumps are commonly used to discharge flow away from release structures into downstream rivers for energy dissipation. However, due to large intersection angles of jet and river flow or the jet impacting position unreasonable, the serious sour of riverbed or bank may occur, threatening the security of hydraulic structure. Hence, the impacting position and direction of jet from ski jump are pressing for research. For obtaining a controllable and desired outflow condition, adding rectangular tetrahedral deflector is a common and effective measure to change the flow direction. In this study, physical experiments and numerical simulation were conducted and the effect of the deflector contraction ratio on the flow deflection angle was revealed. The results indicate that the contraction ratio is a key parameter of the deflector, and a larger contraction ratio contributes to a larger jet deflection angle. Based on the data in the present and previous studies, a new empirical expression for estimating the deflection angle is proposed for rectangular tetrahedral deflector. By contrast with previous research, the calculated result from the expression presents a better agreement with the test data.

Numerical investigation of inlet distortion in a jet engine coupled with Ski-jump of carrier-based aircraft

Contract with land-based aviation, the ski-jump of carrier-based aircraft is confronted with complicated aerodynamic circumstances. More especially, the occurrence of inlet distortion in the aero-engine would endanger its flight safety. This study conducted the inlet distortion of the aero-engine coupled with the ski-jump of carrier-based aircraft by means of numerical simulation. The movement of the aircraft has been characterized by the nested dynamic grid and user-defined function (UDF). The results show that the inlet distortion of the aero-engine has resulted from the suction of high-temperature exhaust gas from the auxiliary intake grille primarily and the aero-engine inlet subsequently. the presence of an intersection angle between the aircraft axis and carrier axis has brought the accumulation of the high-temperature exhaust gas near the left engine while the sucking of flow into the right engine is ‘fresh air’ in the ambiance. Correspondingly, the inlet distortion of the left engine is larger than that of the right engine. For the braking state, the region-averaged relative temperature rises at the AIP section increased by 27.46% compared with the land case. For the slip-jump, the temperature and pressure distortion at the AIP section decreases rapidly with the increase of the slip-jump distance. After the slip-jump distance is greater than 6m, the total temperature and total pressure distortion almost disappeared. The increase in aircraft height, the velocity magnitude of relative wind velocity, and the distance from the take-off point to the Jet Blast Deflector decreased the inlet distortion of the aero-engine. The relative wind from the left wing (α<0°) brought more inlet distortion to the right engine while the relative wind from the right wing (α>0°) brought more inlet distortion to the left engine. The results obtained in this study are significant because they provide the physical mechanism of inlet distortion of aero-engine and can be used for the guidance of the operational safety of carrier-based aircraft.

Effect of the arrangement of cavitation generation unit on the performance of an advanced rotational hydrodynamic cavitation reactor

Hydrodynamic cavitation (HC) is widely considered a promising process intensification technology. The novel advanced rotational hydrodynamic cavitation reactors (ARHCRs), with considerably higher performance compared with traditional devices, have gained increasing attention of academic and industrial communities. The cavitation generation unit (CGU), located on the rotor and/or stator of an ARHCR, is utilized to generate cavitation and consequently, its geometrical structure is vital for the performance. The present work studied, for the first time, the effect of the arrangement of CGU on the performance of a representative ARHCR by employing computational fluid dynamics based on the “simplified flow field” strategy. The effect of CGU arrangement, which was neglected in the past, was evaluated: radial offset distance (c), intersection angle (ω), number of rows (N), circumferential offset angle (γ), and radial spacing (r). The results indicate that the CGU, with an arrangement of a low ω and moderate c, N, γ, and r, performed the highest cavitation efficiency. The corresponding reasons were analyzed by combining the flow field and cavitation pattern. Moreover, the results also exposed a weakness of the “simplified flow field” strategy which may induce the unfavorable “sidewall effect” and cause false high-pressure region. The findings of this work may provide a reference value to the design of ARHCRs.

Station Arrangement Optimization of Photoelectric Theodolites Based on Efficient Traversing Discrete Points

Station arrangement optimization of photoelectric theodolites in shooting ranges presents a non-convex and non-linear problem, and the method required to seek the global optimal solution remains an open question. This paper proposes an efficient traversal algorithm that could solve this problem by utilizing discretization of regions with a finite length of mesh, in which both the terrain of the station arrangement region and the observation airspace region are discretized through triangulation. To enhance the computational efficiency of the traversal algorithm, two strategies are employed to speed up the calculation: reducing the dimension of the observation airspace and using the Euclidean distance matrix to compute the intersection angle. After the global optimal solution with discrete finite precision was obtained through the traversal algorithm, it was then used as the initial points for local mesh refinement and to implement gradient-based optimization in order to further improve the precision of the solution. The proposed approach is demonstrated to be practical through application to numerical examples used for the optimization of station arrangements that involve two to four stations.

A Target Damage Effectiveness Assessment Mathematical Calculation Method with Uncertain Information Based on an Adaptive Fuzzy Neural Network

Aiming to address the issue of assessing the effectiveness of target damage in air defense interception under projectile and target intersection, this paper proposes a novel target damage effectiveness assessment mathematical calculation method using an adaptive fuzzy neural network. The design and calculation methods introduce the target cabin’s damage weight factor, the dispersion error and coverage density and fire density of warhead fragment, and the ratio of the number of warhead fragments to the cross-sectional area of the target as the primary damage factors, and we establish a new model for calculating the target damage efficiency using Takagi-Sugeno adaptive fuzzy neural network with the multiple damage factors. In the designed model, we take the characteristic parameters of warhead fragments formed by the projectile explosion as the sample data and learn the mapping relationship between damage factors and damage effect expressed by the system of fuzzy rule. Combined with the vulnerability weight and damage factors of the target, the fuzzy rule system is applied to predict and calculate the damage probability and damage effectiveness. In addition, we use shot-line technology to set up the intersection criterion between warhead fragments and target, analyze the coordinate relationship of the projectile explosion relative to the target based on the ground coordinate system, and derive the distribution density function of warhead fragment and research a calculation model for target damage probability with multiple vulnerable cabins. Finally, we use the established model to train, test, and calculate the data from the actual projectile and target intersection damage test and present the comparison results to other damage calculation methods. By calculation and comparative analysis, the results show the smaller the distance between projectile and target, as well as the smaller the average intersection angle, and the larger the weight coefficient of the warhead fragment covering the target cabin, the total target damage probability increases obviously. In the two experimental calculations, the target cabin with the largest weight coefficient was considered, and compared with the existing literature, the damage probability of the proposed calculation method was increased by 9.13% and 10.93%, respectively, and it is clear that the proposed target damage assessment method can effectively reflect the real target damage effectiveness in the state of projectile and target intersection.

Learning curves for point-of-care ultrasound image acquisition for novice learners in a longitudinal curriculum

BackgroundA learning curve is graphical representation of the relationship between effort, such as repetitive practice or time spent, and the resultant learning based on specific outcomes. Group learning curves provide information for designing educational interventions or assessments. Little is known regarding the learning curves for Point-of-Care Ultrasound (POCUS) psychomotor skill acquisition of novice learners. As POCUS inclusion in education increases, a more thorough understanding of this topic is needed to allow educators to make informed decisions regarding curriculum design. The purpose of this research study is to: (A) define the psychomotor skill acquisition learning curves of novice Physician Assistant students, and (B) analyze the learning curves for the individual image quality components of depth, gain and tomographic axis.ResultsA total of 2695 examinations were completed and reviewed. On group-level learning curves, plateau points were noted to be similar for abdominal, lung, and renal systems around 17 examinations. Bladder scores were consistently good across all exam components from the start of the curriculum. For cardiac exams, students improved even after 25 exams. Learning curves for tomographic axis (angle of intersection of the ultrasound with the structure of interest) were longer than those for depth and gain. Learning curves for axis were longer than those for depth and gain.ConclusionBladder POCUS skills can be rapidly acquired and have the shortest learning curve. Abdominal aorta, kidney, and lung POCUS have similar learning curves, while cardiac POCUS has the longest learning curve. Analysis of learning curves for depth, axis, and gain demonstrates that axis has the longest learner curve of the three components of image quality. This finding has previously not been reported and provides a more nuanced understanding of psychomotor skill learning for novices. Learners might benefit from educators paying particular attention to optimizing the unique tomographic axis for each organ system.