Angular Sections Research Articles

Adaptation of rectangular and trapezoidal time functions to simulate the rotational motion of the brake disc

Numerical modeling of the rotational motion of the brake disc during frictional heating requires the use of specialized software. In this paper, an alternative approach was proposed consisting in the simulation of the displacement of the heating region contained within the boundaries of the friction surface of the brake pad relative to the stationary disc. The moving heat source effect was obtained using rectangular time functions generated based on the operating parameters and dimensions of the brake components. The first part of the article discusses the mathematical basis for the construction of time curves in relation to the solid brake disc combined with a pad in the shape of the angular section of a ring. Braking simulations were carried out using the finite element method (FEM) based software for 3D, 2D axisymmetric and 1D models of the disc. The calculated temperature filed changes were confronted with the results obtained using the 3D model developed based on standard methods. The temperature on the contact surface of the disc in the position of the mean radius at the end of braking, determined using the 2D axisymmetric and the 3D model with adaptation of rectangular time functions as well as the 3D reference model agreed well and were equal to 157.83 °C, 157.87 °C, and 157.90 °C, respectively. In the second part of the study, the 3D model of periodic heating was extended to the disc brake of a railway vehicle. The results of the calculations for the ventilated disc and segmented brake pad were compared with the experimental data obtained during testing on a full-scale dynamometer test stand. The maximum temperature values obtained on the basis of the 3D-pulse, 3D numerical models and measured on the test stand were equal to 73.3 °C, 74.4 °C and 75.6 °C, respectively. The insignificant temperature difference, i.e. below 3 %, obtained using the 3D-pulse heating model and measured using a thermocouple, confirms the correctness of the developed algorithm for simulating the rotational motion of the disc as well as the calculation methodology incorporating the heat partition coefficient (HPC).

An Overview of Angle Deviations of Fiber-Reinforced Polymer Composite Angular Laminates.

After manufacturing, fiber-reinforced polymer composite laminates may have residual stresses, resulting in warpage in flat structures and angle changes in angular sections. These shape distortions may cause fitting mismatch problems under high-level assembly, and extra efforts to fix these problems may be needed. The present paper only makes an overview of the angle deviation of angular composite laminates made of either thermoset matrix with autoclave curing or thermoplastic matrix with thermoforming. Depending on the positive or negative angle deviation, spring-back or spring-in behavior is observed. There are many parameters, including intrinsic and extrinsic parameters, that could affect the angle deviation. In the first part of this review paper, experimental results concerning the effects of the part angle, part thickness, lay-up sequence, corner angle, flange size, tool material, tool surface, and cure cycle are summarized. Spring-in angles are generally obtained in this part. In the second part, several prediction methods, such as simple equations and finite element methods, are compared to indicate the considered parameters. Some have good agreement and some have larger errors. The crucial differences may be dependent on the micromechanical theories and the input properties of the composite and the constituents.

Design and Comparative Analysis of Pratt Roof Trusses Using Angular and Tubular Steel Sections through Limit State Method

A Pratt truss is a type of truss structure which is used in civil engineering to support heavy loads. It is comprised by the diagonal members and vertical members, which transmits the loads efficiently through a combination of tension and compression which is easy to construction and suitable for both short and medium span. But this project work is made to decide to structural performance employing angular and tubular steel sections by using Limit State Method by considering the economy and strength having 30 m span and rise height 5 m, with the help of software we analyse the truss by using angular and tubular sections. The analysis is carried out through STAAD Pro software and two steel sections were made to find their weight of steel, deflection which decides which structure is more economical to use. The outcomes of this project is that consists of comparative study on Pratt roof truss using angular and tubular steel sections by Limit State Method with help of STAAD Pro software to determine the optimistic, adequate and economic structure, then the loads are applied according to the Is 875 code, assigning steel sections such as channel, I-sections, etc. By the study of project we got the tubular section is economical to use as compared to angular section. Keywords: Structural Analysis, Roof Truss, STAAD PRO, Pratt truss, Limit State Method (IS 800:2007, IS 875-1975 (Part I, II & III)

Dynamic modeling of a 3-D 4-directional braided composite beam with a central rigid body

Although 3-D braided composites can be incorporated with rotating central body-beam systems, there are currently few dynamic models for the rotating systems made of braided composites. This paper proposes a dynamic model of a 3-D 4-directional braided composite beam with a central rigid body. Based on the Timoshenko beam hypothesis, the displacements of the composite beam are described by the arc-length coordinate, and the displacement field is represented by the slope angle, tensile strain, and shear angle. The assumed mode method is employed to discrete the displacement field, and the dynamic model of the system is derived from the Lagrange equation. The equivalent stiffness matrices of 3-D 4-directional braided composite beams with different braiding angles are obtained using the volume average method. The influences of different angular velocities, braiding angles, and beam section parameters on the system's dynamic characteristics are studied. The model proposed in this study can be utilized to estimate the dynamic responses of braided composite blades, and lays the theoretical foundation for analyzing dynamic characteristics of anisotropic beams in engineering.

The flood of October 9, 2018 in the city centre of Sant Llorenç des Cardassar (Mallorca)

Since the 1940s, the city centre of Sant Llorenç des Cardassar has suffered from several flooding episodes from the several tributaries of ca n’Amer creek. Five lives lost and a significant impact on the population were the result of the most relevant flood in the series that occurred in 2018. In this paper, an analysis of the historical relationship of the village with floods, the answer provided by the administration to those floods, and the geographic setting and the anthropic actions on the land are considered. Using the data collected by direct observation, witnesses, and graphs and fieldwork, a thorough investigation of the volume, flow, direction and levels of water has been developed. This translates into an exhaustive mapping of the event, discriminating the hydraulic behaviour in each of the affected roads and showing the sequential development of the flood. Flooding is a combination of severe stream flows, avulsion processes and angular sections that combine with infraestructures that interfere with the flow direction and prevent its reintegration into the main channel and where the streets become active channels.

Axial compressive behavior of non-symmetric cold-formed angular column with complex edge

Currently, the assembled-type light steel (ATLS) modular house is increasingly used for apartments, schools, hotels, and other similar buildings with repetitive units, in which the non-symmetric cold-formed angular section is usually served as column in the module unit. However, the compressive behavior and design method of the non-symmetric cold-formed angular column remain unknown due to the complex edge. In this paper, a series of tests were conducted on the axial compressive behavior of the non-symmetric cold-formed angular column. A total of 12 specimens with complex edge were tested under monotonic axial compression. A special support was designed at the end of the column to apply the axial compression along different loading axes of the complex section. The failure mode and axial compressive capacity of the test specimens were revealed and discussed in detail. It indicated that the loading axis significantly influenced the failure mode and axial compressive capacity of the non-symmetric cold-formed angular column. Furthermore, a 3D finite element model was developed and validated against the test results to broaden the research. Lastly, given that the current design codes for steel structures, as used in Europe, Australia/New Zealand and North, the relevant codified design was utilized to evaluate the axial compressive capacity of unequal angular column with a double edge fold stiffener, based on the obtained test data.

Lattice design for angular dispersion enhanced microbunching in storage rings

Generation of coherent radiation pulses is of remarkable interest in the synchrotron light source community. A novel technique has been proposed to produce temporal coherent radiation in ref. [1]. In this scheme, an oblique incidence seed laser is utilized to introduce an angular modulation which is converted to microbunching by an angular dispersion section. In this paper, a specific design of the angular dispersion section is given to realize the coupling between transverse and longitudinal directions which satisfied the microbunching requirements of this technique. Numerical simulation results demonstrate that this lattice can be used to enhance the bunching factor at very high harmonics of the seed laser. The lattice structure has good flexibility, the elements of the transport matrix related to microbunching can be easily adjusted, and the beta function in the radiator can be simply optimized by adjusting the magnets of the transport line.

Hysteroscopic Intact Removal of Angular and Caesarean Scar Pregnancy: A Novel and Markedly Less Invasive Surgical Treatment

Introduction: Ectopic pregnancy is the most common cause of mortality during the first trimester of pregnancy, and intrauterine ectopic pregnancies show significantly higher morbidity and mortality than extrauterine ones. Despite being less invasive, safety and effectiveness of the hysteroscopic treatment are still unclear. Moreover, such approach is not standardized. We aimed to evaluate safety and effectiveness of hysteroscopic intact removal of angular or cesarean section scar pregnancies, defining a novel and markedly less invasive hysteroscopic technique with a 5-mm Bettocchi hysteroscope or a 3.5-mm Versascope hysteroscope. Materials and Methods: Medical records and video archives were reviewed for all the patients with angular or caesarean scar pregnancies treated with hysteroscopic intact removal technique from January 2000 to December 2018 at our Department. Success and complication rates were assessed. Results: Four patients with angular (n = 1) or cesarean scar pregnancy (n = 3) met inclusion criteria. Case #1 was treated with bipolar resectoscope, cases #2 and #3 with 5-mm Bettocchi hysteroscope, and case #4 with 3.5-mm Versascope hysteroscope. Cases #2–4 did not require cervical dilatation. Before hysteroscopic treatment, cases #2–4 underwent unsuccessful medical therapy with multiple-dose methotrexate. Hysteroscopic treatment success rate was 100%, while complication rate was 0%. All patients were treated with a novel technique: hysteroscopic intact removal of angular or cesarean scar pregnancies. Such technique was described step-by-step. Conclusions: Hysteroscopic treatment of angular and cesarean scar pregnancies may be a safe and effective minimally invasive option. The novel technique of hysteroscopic intact removal technique may allow a markedly less invasive approach.

Shear behavior of stiffened single perforated lean duplex stainless steel (LDSS) rectangular hollow beams

This paper presents the study on shear behavior of stiffened single perforated LDSS rectangular hollow beam, considering various orientations / patterns viz., inclined (IS), vertical (VS), horizontal (HS) and ring (RS); and effect of various cross-sections i.e. flat, angular and semi-circular (considering same material consumption). Based on the study, it has been found that in general, inclined stiffener (with flat cross-section) is relatively most effective in enhancing the shear capacity of perforated beams. For the inclined stiffeners, it is observed that the rate of increase in shear capacity (Vu/Vy) increases (in a non linear trend) with increasing stiffener length for higher stiffener thicknesses. In the case of vertical and horizontal stiffeners, there appears to have no/little significant improvement in shear capacity for both the variation in length, width and thickness. For the ring stiffeners, it is found that, shear capacity increases with increase in both breadth and thickness of the stiffeners. Comparison made between angular and semi-circular sections (keeping the same cross sectional area) showed that both the sections predicted similar behavior of shear capacity.

Analytical volume model for optimized spatial radar bat detection in onshore wind parks.

To develop mitigation measures for the protection of bats in close proximity to onshore wind turbines, new detection techniques covering large-scale environments and techniques, which are able to track individuals are required. Radar based observations, successfully applied in ornithological studies, offer a promising potential, but come with challenges regarding the comparability of measurements and noise interference (ground clutter) from objects within detection range. This paper presents improvements of a commercially available inexpensive pulse radar for 3D spatial detection of bat-sized objects in onshore wind parks. A new analytical spatial detection volume model is presented incorporating calibrated radar data and landscape parameters such as clutter. Computer simulation programs to process the analytical spatial detection volume model were developed. For model calibration, the minimum signal power of the radar was experimentally determined with the radar cross section (RCS) of an artificial bat (similar to Nyctalus noctula), resulting in a maximum detection range of 800 m and a corresponding RCS of 12.7 cm². Additionally, the spatial volume for radar detection was optimized with a clutter shielding fence (CSF). Adjusting the volume model by incorporating a theoretical model of the CSF, an extension of the detection volume by a factor of 2.5 was achieved, while the total volume of a 105° horizontal angular radar image section yields 0.0105 km³. Extrapolation and comparison with state-of-the-art acoustic bat detection result in a 270 times larger volume, confirming the large-scale detection capabilities of the pulse radar.

The magnetic field from a homogeneously magnetized cylindrical tile

The magnetic field of a homogeneously magnetized cylindrical tile geometry, i.e. an angular section of a finite hollow cylinder, is found. The field is expressed as the product between a tensor field describing the geometrical part of the problem and a column vector holding the magnetization of the tile. Outside the tile, the tensor is identical to the demagnetization tensor. We find that four components of the tensor, Nxy,Nxz,Nyz and Nzy, can be expressed fully analytically, while the five remaining components, Nxx,Nyx,Nyy,Nzx and Nzz, contain integrals that have to be evaluated numerically. When evaluated numerically the tensor is symmetric. A comparison between the found solution, implemented in the open source magnetic framework MagTense, and a finite element calculation of the magnetic flux density of a cylindrical tile shows excellent agreement.

A novel high speed multi-objective evolutionary optimisation algorithm

Multi-objective optimisation problems (MOOPs) consider multiple objectives simultaneously. Solving these problems does not render one unique solution but instead a set of equally optimal solutions, i.e., the Pareto front. The goal of solving a MOOP is to accurately and efficiently approximate the Pareto front. The use of evolutionary optimisation algorithms is widespread in this discipline. During each iteration, parent solutions are combined and mutated to create new offspring solutions. Both populations are subsequently combined and sorted. Only the N fittest solutions of the combined set are selected as the parent solutions for the subsequent iteration. The fitness of a solution is defined by its convergence to the Pareto front and its contribution to the overall solution diversity. Widely used evolutionary algorithms, like NSGA-II (Deb et al., 2002), use non-dominated sorting to assess the convergence of solutions and the concept of crowding distance to ensure a high solution diversity. Both concepts, however, require that all N solutions of the population are compared with all other (N — 1) solutions for both aspects, and this for all M objectives. This results in a computational complexity of O(MN2). In this contribution, a novel evolutionary algorithm is presented, boasting a significantly lower computational complexity of O(N log(N)). This is achieved by subdividing the feasible space into angular sections. Solutions are scored based on their distance from the current Utopia point and the overall crowdedness of their respective section. Sorting the population based on the attributed scores allows the selection of the N fittest solutions, without having to mutually compare them.

Validation of Computerized Quantification of Ocular Redness.

PurposeTo show feasibility of computerized techniques for ocular redness quantification in clinical studies, and to propose an automatic, objective method.MethodsSoftware for quantification of redness of the bulbar conjunctiva was developed. It provides an interface for manual and automatic sclera segmentation along with automated alignment of region of interest to enable estimation of changes in redness. The software also includes the redness scoring methods: (1) contrast-limited adaptive histogram equalization (CLAHE) in red-green-blue (RGB) color model, (2) product of saturation and hue in hue-saturation-value (HSV), and (3) average of angular sections in HSV. Our validation pipeline compares the scoring outcomes from the perspectives of segmentation reliability, segmentation precision, segmentation automation, and the choice of redness scoring methods.ResultsNinety-two photographs of eyes before and after provoked redness were evaluated. Redness in manually segmented images was significantly different within human observers (interobserver, P = 0.04) and two scoring sessions (intraobserver, P < 0.001). Automated segmentation showed the smallest variability, and can therefore be seen as a robust segmentation method. The RGB-based scoring method was less sensitive in redness assessment.ConclusionsComputation of ocular redness depends heavily on sclera segmentation. Manual segmentation appears to be subjective, resulting in systematic errors in intraobserver and interobserver settings. At the same time, automatic segmentation seems to be consistent. The scoring methods relying on HSV color space appeared to be more consistent.Translational RelevanceComputerized quantification of ocular redness holds great promise to objectify ocular redness in the standard clinical care and, in particular, in clinical trials.

On Existence and Uniqueness to Homogeneous Boltzmann Flows of Monatomic Gas Mixtures

We solve the Cauchy problem for the full non-linear homogeneous Boltzmann system of equations describing multi-component monatomic gas mixtures for binary interactions in three dimensions. More precisely, we show existence and uniqueness of the vector value solution by means of an existence theorem for ODE systems in Banach spaces under the transition probability rates assumption corresponding to hard potentials rates in the interval $(0,1]$, with an angular section modeled by an integrable function of the angular transition rates modeling binary scattering effects. The initial data for the vector valued solutions needs to be a vector of non-negative measures with finite total number density, momentum and strictly positive energy, as well as to have a finite $L^1_{k_*}(\mathbb{R}^3)$-integrability property corresponding to a sum across each species of $k_*$-polynomial weighted norms depending on the corresponding mass fraction parameter for each species as much as on the intermolecular potential rates, referred as to the scalar polynomial moment of order $k_*$. The existence and uniqueness rigorous results rely on a new angular averaging lemma adjusted to vector values solution that yield a Povzner estimate with constants that decay with the order of the corresponding dimensionless scalar polynomial moment. In addition, such initial data yields global generation of such scalar polynomial moments at any order as well as their summability of moments to obtain estimates for corresponding scalar exponentially decaying high energy tails, referred as to scalar exponential moments associated to the system solution. Such scalar polynomial and exponential moments propagate as well.

François Viète’s revolution in algebra

Francios Viete (1540–1603) was a geometer in search of better techniques for astronomical calculation. Through his theorem on angular sections he found a use for higher-dimensional geometric magnitudes which allowed him to create an algebra for geometry. We show that unlike traditional numerical algebra, the knowns and unknowns in Viete’s logistice speciosa are the relative sizes of non-arithmetized magnitudes in which the “calculations” must respect dimension. Along with this foundational shift Viete adopted a radically new notation based in Greek geometric equalities. His letters stand for values rather than types, and his given values are undetermined. Where previously algebra was founded in polynomials as aggregations, Viete became the first modern algebraist in working with polynomials built from operations, and the notations reflect these conceptions. Viete’s innovations are situated in the context of sixteenth-century practice, and we examine the interpretation of Jacob Klein, the only historian to have conducted a serious inquiry into the ontology of Viete’s “species”.

Generating attosecond x-ray pulses through an angular dispersion enhanced self-amplified spontaneous emission free electron laser

We propose a scheme that can generate attosecond x-ray pulses through an angular dispersion enhanced self-amplified spontaneous emission (ESASE) free electron laser (FEL). In this scheme, an angular dispersion section is implemented into a conventional ESASE set-up, together with a few cycle laser pulse to manipulate the electron beam effectively. During the procedure, the transverse-longitudinal phase space coupling is introduced into the electron beam in addition to the energy modulation and momentum compaction processes. As a result, the peak current of the electron beam will be strengthened significantly within a narrow width of the electron bunch, which can be used to generate ultrashort FEL pulses. Comparing to a conventional ESASE scheme, the proposed scheme can reduce the required modulation laser power by at least one order of magnitude. The signal-to-noise ratio of the final FEL radiation pulses can also be improved. In addition, we discuss the possibility of using this scheme to generate two-pulse two-color x-ray FEL with tunable central wavelengths and time delays for a conceivable x-ray pump/x-ray probe experiment.

Optimal collimator rotation based on the outline of multiple brain targets in VMAT

BackgroundThe aim of this study was to investigate the dosimetric quality in volumetric modulated arc therapy (VMAT) plans with optimal collimator angles that can represent the outline of multiple brain targets.MethodsTwenty patients with multiple target volumes in the brain cases were selected retrospectively. To better represent the outline of the multiple brain targets, four conformal arc plans were generated for each patient using one full arc with four collimator settings. The optimal collimator angles calculated from the integrated multi-leaf collimator (MLC) aperture that had the smallest aperture size for certain collimator settings of the conformal arc plan were selected. VMAT plans with the optimal collimator angles with angular sections of 40° and 60° (Colli-VMAT (40°), Colli-VMAT (60°)) were generated, followed by evaluation of field sizes, dose-volumetric parameters and total monitor units (MUs).ResultsPatient-averaged values of field sizes for Colli-VMAT (40°) (111.5 cm2) were lowest and 1.3 times smaller than those for Std-VMAT (143.6 cm2). Colli-VMAT plans improved sparing of most normal organs but for brain stem and left parotid gland. For the total MUs, the averaged values obtained with the Colli-VMAT (40°) (390 ± 148 MU) were smaller than those obtained with the Std-VMAT (472 ± 235 MU).ConclusionsThe Colli-VMAT plans with smaller angular sections could be suitable in the clinic for multiple brain targets as well as for irregularly shaped targets. Determination of the optimal collimator rotation generally showed good normal tissue sparing and MU reduction for multiple brain targets.

François Viète’s revolution in algebra

Francios Viete (1540–1603) was a geometer in search of better techniques for astronomical calculation. Through his theorem on angular sections he found a use for higher-dimensional geometric magnitudes which allowed him to create an algebra for geometry. We show that unlike traditional numerical algebra, the knowns and unknowns in Viete’s logistice speciosa are the relative sizes of non-arithmetized magnitudes in which the “calculations” must respect dimension. Along with this foundational shift Viete adopted a radically new notation based in Greek geometric equalities. His letters stand for values rather than types, and his given values are undetermined. Where previously algebra was founded in polynomials as aggregations, Viete became the first modern algebraist in working with polynomials built from operations, and the notations reflect these conceptions. Viete’s innovations are situated in the context of sixteenth-century practice, and we examine the interpretation of Jacob Klein, the only historian to have conducted a serious inquiry into the ontology of Viete’s “species”.

Dosimetric effects of sectional adjustments of collimator angles on volumetric modulated arc therapy for irregularly-shaped targets.

PurposeTo calculate an optimal collimator angle at each of sectional arcs in a full-arc volumetric modulated arc therapy (VMAT) plan and evaluate dosimetric quality of these VMAT plans comparing full-arc VMAT plans with a fixed collimator angle.MethodsSeventeen patients who had irregularly-shaped target in abdominal, head and neck, and chest cases were selected retrospectively. To calculate an optimal collimator angle at each of sectional arcs in VMAT, integrated MLC apertures which could cover all shapes of target determined by beam’s-eye view (BEV) within angular sections were obtained for each VMAT plan. The angular sections were 40°, 60°, 90° and 120°. When the collimator settings were rotated at intervals of 2°, we obtained the optimal collimator angle to minimize area size difference between the integrated MLC aperture and collimator settings with 5 mm-margins to the integrated MLC aperture. The VMAT plans with the optimal collimator angles (Colli-VMAT) were generated in the EclipseTM. For comparison purposes, one full-arc VMAT plans with a fixed collimator angles (Std-VMAT) were generated. The dose-volumetric parameters and total MUs were evaluated.ResultsThe mean dose-volumetric parameters for target volume of Colli-VMAT were comparable to Std-VMAT. Colli-VMAT improved sparing of most normal organs but for brain stem, compared to Std-VMAT for all cases. There were decreasing tendencies in mean total MUs with decreasing angular section. The mean total MUs for Colli-VMAT with the angular section of 40° (434 ± 95 MU, 317 ± 81 MU, and 371 ± 43 MU for abdominal, head and neck, and chest cases, respectively) were lower than those for Std-VMAT (654 ± 182 MU, 517 ± 116 MU, and 533 ± 25 MU, respectively).ConclusionsFor an irregularly-shaped target, Colli-VMAT with the angular section of 40° reduced total MUs and improved sparing of normal organs, compared to Std-VMAT.

Numerical computation of a reactor vessel melting under external cooling conditions

ABSTRACTNumerical computations are performed for melting and natural convection in the liquefied region of a reactor vessel under external cooling to find more thermal margin for in-vessel retention. Existing typical experiment and calculations for gallium melting are used for the validation. The transient flow field in the liquefied region and the melt front movement analyzed are compared with those from finite-element and finite-volume methods. Reasonable agreements are achieved with respect to melt progression and flow configuration in the liquefied zone. A three-dimensional geometrical model for an azimuthally 3° angular section of the APR1400 pressurized water reactor vessel is prepared based on this verification, and a conservative heat flux profile from the corium inside with a concentrated heat flux from the metallic layer of 2.1 MW/m2, which is greater than maximum critical heat flux, is applied to the vessel model assuming constant exterior temperatures of 400 and 1000 K. The results show that even though the vessel inside heat flux is much greater than the critical heat flux, this does not intensively melt a vessel due to combined effects of latent heat absorption during the melting and the remaining heat spreading through the entire vessel.