Curvature Coefficients Research Articles

Composition of particle size at Regency Beach, Port Dickson

In 2015, the coastline in Negeri Sembilan was recorded to have 10.2 km erosion, which is 17.59% of the total 58 km of coastline in the state. Regency Beach, located in Port Dickson, is one of the areas affected by erosion. This preliminary study was conducted to determine the sediment distribution along the coast of Regency Beach. Nine (9) sampling points were identified starting from the lowest water line up to 40 meters inland, over 800 m along the coast. Sedimentary samples were taken in pore strata and analysed to obtain soil characteristics and particle size classification. According to the USCS classification, the sediment in the study area may be considered as moderate sand. Values of uniformity coefficients, Cu and curvature coefficients, Cc show a uniformly uniform distribution with very low moisture content.

Friction Characteristics of Post‐Tensioned Tendons of Full‐Scale Structures Based on Site Tests

In the design of prestressing concrete structures, the friction characteristics between strands and channels have an important influence on the distribution of prestressing force, which can be considered comprehensively by curvature and swing friction coefficients. However, the proposed friction coefficient varies widely and may lead to an inaccurate prestress estimation. In this study, four full‐scale field specimens were established to measure the friction loss of prestressing tendons with electromagnetic sensors and anchor cable dynamometers to evaluate the friction coefficient. The least square method and Bayesian quantile regression method were adopted to calculate the friction coefficient, and the results were compared with that in the specifications. Field test results showed that Bayesian quantile regression method was more effective and significant in the estimation of the friction coefficient.

On Relation between Bulk, Surface and Curvature Parts of Nuclear Binding Energy within the Model of Hexagonal Clusters

Using the model of hexagonal clusters we express the surface, curvature and Gauss curvature coefficients of the nuclear binding energy in terms of its bulk coefficient. Using the derived values of these coefficients and a single fitting parameter we are able to reasonably well describe the experimental binding energies of nuclei with more than 100 nucleons. To improve the description of lighter nuclei we introduce the same correction for all the coefficients. In this way we determine the apparent values of the surface, curvature and Gauss curvature coefficients which may be used for infinite nuclear matter equation of state. This simple model allows us to fix the temperature dependence of all these coefficients, if the temperature dependence for the bulk term is known. The found estimates for critical temperature are well consistent both with experimental and with theoretical findings.

A sinusoidal beam theory for functionally graded sandwich curved beams

To the best of the authors’ knowledge, there is no research work available on FG sandwich curved beams in the whole variety of literature. Therefore, the analysis presented on static behaviour of FG sandwich curved beams in this study is the main contribution and the novelty of the present study. A sinusoidal beam theory considering the effects of transverse normal stress/strain is applied for the bending analysis of FG sandwich beams curved in elevation. The beam has functionally graded skins at top and bottom and isotropic core at the middle. Material properties of FG skins are varied through the thickness according to the power law distribution. The present theory accounts for sinusoidal variation of axial strain and cosine distribution of transverse shear strain through the thickness of the beam. Governing equations of equilibrium are derived using Hamilton’s principle. Analytical solutions for simply supported curved beam are obtained using Navier’s solution procedure. The non-dimensional numerical results are obtained for different radii of curvature and various power law coefficients. The present study contributes many new results on the bending analysis of functionally graded sandwich beams curved in elevation for the reference of future research in this area.

Transport coefficients in the Fourier shape parametrization

An innovative parametrization of nuclear shapes, based on a Fourier expansion of the square distance from the surface of the nucleus to the symmetry axis is introduced. Surface, curvature and Coulomb energy coefficients of a charged liquid drop, that determine the semiclassical nuclear energy, are evaluated within this shape parametrization, together with the wall-friction and the irrotational-flow mass tensors. These transport coefficients are important ingredients of many nuclear models describing nuclear structure and dynamics. A numerical code allowing for the determination of all these quantities for a huge variety of nuclear shapes is made available to the interested user. Program summaryProgram title: inerfricProgram Files doi:http://dx.doi.org/10.17632/gtvbc8b7sw.1Licensing provisions: GPLv3Programming language: FortranNature of problem: The inertia tensor evaluated in the hydrodynamical model using the Werner–Wheeler approximation generalized to nonaxial shapes is evaluated, together with the friction tensor using the wall formula, and the shape functions that define the liquid-drop energy in terms of surface, curvature, Coulomb and congruence energy. For the description of the fission process, the mass ratio of the nascent fission fragments and their centre-of-mass distance is also evaluated together with the quadrupole moment and the moments of inertia for rotation of the deformed shape.Solution method: All these quantities are evaluated in our new rapidly converging Fourier shape parametrization, able to describe a huge variety of nuclear shapes, simply by reading in the (up to 7) shape parameters determining in an unambiguous way the nuclear deformation and corresponding for the (4) principal parameters to the nuclear elongation, left–right asymmetry, non axiality and neck degree of freedom, the remaining 3 allowing, if necessary, to optimize the evaluation of the asymmetry and neck degrees of freedom.

A comprehensive study on the speed-varying stiffness of ball bearing under different load conditions

The stiffness as one of the most important dynamic characteristics of ball bearing, has a great influence on the service performance of bearing and rotor systems. To obtain and analyze the stiffness matrix of ball bearing under arbitrary load conditions, this paper proposed a novel mathematical method for ball bearing modeling and stiffness matrix calculation based on a new initial condition assumption. Based on this, a comprehensive and systematical study to investigate the effect of rotating speed on the stiffness for ball bearing under three typical load conditions has been presented (the pure axial load condition, the pure radial load condition and the combined loads condition). And the influences of bearing basis structure parameters including the internal clearance, ball diameter, inner and outer raceway curvature coefficients on the change rule of the stiffness along with speed of ball bearing under three typical load conditions have been given. The results show that the proposed model has a high versatility, and the change rules of the stiffness along with rotating speed are greatly influenced by the load conditions, bearing structural parameters. Therefore, this paper not only presents a complete algorithm for the modeling and stiffness calculation of ball bearing under arbitrary load conditions, but also provides important guidance for the design of bearing and rotor systems.

Peripheral refraction and spherical aberration profiles with single vision, bifocal and multifocal soft contact lenses

PurposeTo compare the peripheral refraction and spherical aberration profiles along three visual field meridians of 16 commercial single vision (SV), bifocal (BF) and multifocal (MF) test contact lenses with a single vision control. MethodForty-four participants [24.2±2.4 years, SE: −0.50 to −4.50D] were randomly fitted, contra-laterally, with 6 SV's [Air Optix Aqua (control), Acuvue Oasys, Biofinity, Clariti, Night & Day and Proclear], 3 BF's [Acuvue Bifocal low and high add, MiSight] and 8 MF's [Proclear D & N in 1.5 and 2.5D adds; AirOptix, PureVision low & high adds]. Peripheral refraction was performed across horizontal, oblique and vertical meridians, with lenses on eye using the BHVI-EyeMapper. The power vectors M, J0, J45 and the spherical aberration coefficient were analysed. The peripheral refraction and aberration profiles of the test lenses were compared with the profiles of the control lens using curvature and slope coefficients. ResultsCompared to the control, a relative peripheral hyperopic shift (M), a less negative J0 curvature coefficient along the horizontal meridian, a less positive J0 curvature coefficient along the vertical meridian, a less negative J45 curvature coefficient along the oblique meridian and a more positive spherical aberration curvature coefficient along most meridians was seen with the Acuvue Bifocal and all center-near multifocal lenses. For the center-distance multifocal lenses the direction of the curvature coefficients of the same refraction and aberration components was opposite to that of the center-near lenses.The greatest differences in the slope coefficients when compared to the control were found for the Acuvue Bifocal lenses and all multifocal contact lenses for the refractive component M and the spherical aberration coefficient along the horizontal visual field meridian, with the Acuvue Bifocal and the center-near multifocal lenses having more positive coefficients and the center-distance lenses having more negative coefficients. ConclusionWhen worn on eye, different commercially available lens types produce differences in the direction and magnitude of the peripheral refraction and spherical aberration profiles along different visual field meridians. This information may be relevant to refractive development and myopia control.

Friction characteristics of post-tensioning tendons in full-scale structures

Friction characteristics between the strands and the duct have a significant effect on the distribution of prestressing force and can be incorporated by the curvature and wobble friction coefficients in the design of prestressed concrete structures. However, the recommended friction coefficients show a wide range of variation, which can cause the inaccurate estimation of prestressing force. In this study, the friction coefficients were evaluated based on the strains of tendons measured by Smart Strands using optical fiber sensors in a full-scale test specimen and two actual long-span girder bridges. The test specimen was investigated to determine how the duct shapes and other factors affect the friction coefficients. Simultaneous equations method and least squares method for obtaining friction coefficients were employed and the results were compared in the actual bridges. This study shows one of the applications of the developed Smart Strand system that can overcome several drawbacks of the existing measurement system.

Determination of lateral tire drag coefficients to achieve the required performance characteristics of machine-tractor unit

This article considers the possibility of determining by analytical calculations such indicators of the drag coefficients for lateral removal of the pneumatic tires of the front and rear wheels of a tractor, at which acceptable traction characteristics of the tractor, the required performance of the unit and the provision of a given trajectory movement of the unit will be provided. Developed by Mstislav Keldysh theory of the rolling of a pneumatic wheel gives the most appropriate model of lateral slip. With an unsteady lateral slip, the center of the contact imprint describes a trajectory called the tire rolling line. If there is no slip, the middle line of the tread within the contact area, coincides with the rolling line. So in the vicinity of the center of the site, its absolute speed and angular velocity of this area equals zero. And the curvature of these coincident lines is determined by the lateral and angular deformations of the tire. For the practical implementation of the adopted design models of the tire, it is necessary in the equations to determine the ratio of the curvature coefficients and the magnitude of the slip function. Experimental studies of a tilled unit with a blocked cultivator sample are given.

ОСОБЕННОСТИ ГИДРАВЛИКИ РЕЧНЫХ УЧАСТКОВ РУСЛОВЫХ ЗИМОВАЛЬНЫХ ЯМ РЕКИ ИРТЫШ В ПЕРИОД ОТКРЫТОЙ ВОДЫ

The article describes features of the hydraulics of the Irtysh riverbed in the sections of significant fish concentrations -wintering holes - in the open water period. There have been explored the waters of the largest (in area and in depth) Gornoslinkinskaya and Kondinskaya riverbed depressions located in the Uvat and Khanty-Mansi districts of the Tyumen region and Khanty-Mansi Autonomous District, respectively. The bathymetric characteristics of wintering holes were studied using computerized hydroacoustic complex AsCor (Promgidroakustika, Ltd., Petrozavodsk). To create the bottom relief of riverbeds there were used geographic information software programs Surfer 9.0 and Map Viewer 6.0. The study of the species composition of the fish population was carried out conducting control catches with stationary and drift nets. It has been found that, as a result of the combination of features of the riverbed, on the investigated sectors there is formed a complex hydrodynamic and turbulent environment. The holes are located on meanders with coefficients of high curvature of the bend of a channel, there have been found the ranges with narrowing channels at the entrance into the turn. In the process of the channel narrowing there occurs deepening of dynamic river flow axis and eroding of the bottom, which may prevent silting of the wintering holes. Significant differences in the depths cause a compensating current. Due to the bend of the riverbed in the water areas there are formed whirlpool zones, and arising transverse water currents close the surface and bottom streams of the river flow. The heterogeneous hydrodynamic environment of the Kondinskaya depression is complicated by the fact that the Konda flows into the bend of the Irtysh; as a result, there takes place an exchange of river impulses. Thus, when the longitudinal flow velocity is imposed on the transverse flows, there appears a spiral movement of the water masses and vertical vortex structures - whirlpools resulting in optical (turbidity) and turbulent (hydrodynamic) heterogeneity in the water column of the riverbed wintering holes.

Scattering due to geometry: Case of a spinless particle moving on an asymptotically flat embedded surface

A nonrelativistic quantum mechanical particle moving freely on a curved surface feels the effect of the nontrivial geometry of the surface through the kinetic part of the Hamiltonian, which is proportional to the Laplace-Beltrami operator, and a geometric potential, which is a linear combination of the mean and Gaussian curvatures of the surface. The coefficients of these terms cannot be uniquely determined by general principles of quantum mechanics but enter the calculation of various physical quantities. We examine their contribution to the geometric scattering of a scalar particle moving on an asymptotically flat embedded surface. In particular, having in mind the possibility of an experimental realization of the geometric scattering in a low density electron gas formed on a bumped surface, we determine the scattering amplitude for arbitrary choices of the curvature coefficients for a surface with global or local cylindrical symmetry. We also examine the effect of perturbations that violate this symmetry and consider surfaces involving bumps that form a lattice.

Interpolating Spline Curve-Based Perceptual Encryption for 3D Printing Models

With the development of 3D printing technology, 3D printing has recently been applied to many areas of life including healthcare and the automotive industry. Due to the benefit of 3D printing, 3D printing models are often attacked by hackers and distributed without agreement from the original providers. Furthermore, certain special models and anti-weapon models in 3D printing must be protected against unauthorized users. Therefore, in order to prevent attacks and illegal copying and to ensure that all access is authorized, 3D printing models should be encrypted before being transmitted and stored. A novel perceptual encryption algorithm for 3D printing models for secure storage and transmission is presented in this paper. A facet of 3D printing model is extracted to interpolate a spline curve of degree 2 in three-dimensional space that is determined by three control points, the curvature coefficients of degree 2, and an interpolating vector. Three control points, the curvature coefficients, and interpolating vector of the spline curve of degree 2 are encrypted by a secret key. The encrypted features of the spline curve are then used to obtain the encrypted 3D printing model by inverse interpolation and geometric distortion. The results of experiments and evaluations prove that the entire 3D triangle model is altered and deformed after the perceptual encryption process. The proposed algorithm is responsive to the various formats of 3D printing models. The results of the perceptual encryption process is superior to those of previous methods. The proposed algorithm also provides a better method and more security than previous methods.

Computation at a coordinate singularity

Coordinate singularities are sometimes encountered in computational problems. An important example involves global atmospheric models used for climate and weather prediction. Classical spherical coordinates can be used to parameterize the manifold – that is, generate a grid for the computational spherical shell domain. This particular parameterization offers significant benefits such as orthogonality and exact representation of curvature and connection (Christoffel) coefficients. But it also exhibits two polar singularities and at or near these points typical continuity/integral constraints on dependent fields and their derivatives are generally inadequate and lead to poor model performance and erroneous results. Other parameterizations have been developed that eliminate polar singularities, but problems of weaker singularities and enhanced grid noise compared to spherical coordinates (away from the poles) persist. In this study reparameterization invariance of geometric objects (scalars, vectors and the forms generated by their covariant derivatives) is utilized to generate asymptotic forms for dependent fields of interest valid in the neighborhood of a pole. The central concept is that such objects cannot be altered by the metric structure of a parameterization.The new boundary conditions enforce symmetries that are required for transformations of geometric objects. They are implemented in an implicit polar filter of a structured grid, nonhydrostatic global atmospheric model that is simulating idealized Held–Suarez flows. A series of test simulations using different configurations of the asymptotic boundary conditions are made, along with control simulations that use the default model numerics with no absorber, at three different grid sizes. Typically the test simulations are ∼20% faster in wall clock time than the control—resulting from a decrease in noise at the poles in all cases. In the control simulations adverse numerical effects from the polar singularity are observed to increase with grid resolution. In contrast, test simulations demonstrate robust polar behavior independent of grid resolution.

Neon ion beam induced pattern formation on amorphous carbon surfaces

We investigate the ripple pattern formation on amorphous carbon surfaces at room temperature during low energy Ne ion irradiation as a function of the ion incidence angle. Monte Carlo simulations of the curvature coefficients applied to the Bradley-Harper and Cater-Vishnyakov models, including the recent extensions by Harrison-Bradley and Hofsäss predict that pattern formation on amorphous carbon thin films should be possible for low energy Ne ions from 250 eV up to 1500 eV. Moreover, simulations are able to explain the absence of pattern formation in certain cases. Our experimental results are compared with prediction using current linear theoretical models and applying the crater function formalism, as well as Monte Carlo simulations to calculate curvature coefficients using the SDTrimSP program. Calculations indicate that no patterns should be generated up to 45° incidence angle if the dynamic behavior of the thickness of the ion irradiated layer introduced by Hofsäss is taken into account, while pattern formation most pronounced from 50° for ion energy between 250 eV and 1500 eV, which are in good agreement with our experimental data.

Characteristic of size distribution of rock chip produced by rock cutting with a pick cutter

Chip size distribution can be used to evaluate the cutting efficiency and to characterize the cutting behavior of rock during cutting and fragmentation process. In this study, a series of linear cutting tests was performed to investigate the effect of cutting conditions (specifically cut spacing and penetration depth) on the production and size distribution of rock chips. Linyi sandstone from China was used in the linear cutting tests. After each run of linear cutting machine test, the rock chips were collected and their size distribution was analyzed using a sieving test and image processing. Image processing can rapidly and cost-effectively provide useful information of size distribution. Rosin-Rammer distribution pamameters, the coarseness index and the coefficients of uniformity and curvature were determined by image processing for different cutting conditions. The size of the rock chips was greatest at the optimum cut spacing, and the size distribution parameters were highly correlated with cutter forces and specific energy.

Design and Construction of a Piled Mountain with Engineered Municipal Construction Waste over Soft Clay

The deformation mechanism of engineered municipal construction waste (EMCW) is complicated and different from that of the traditional soil. A series of field tests and field measurements were performed on the piled mountain project to investigate the deformation characteristics of EMCW during the construction waste accumulation. Experimental studies revealed that EMCW was defined as a kind of heterogeneous soil with well-graded soil. The coefficients of uniformity were all greater than 10, while the coefficients of curvature were between 1 and 3. The permeability had approximately the same performance as the sandy gravel did. The field test results showed EMCW had the characteristics of small deformation and the time effect of loading. The p–s curves indicated that the bearing capacity of construction waste improved after 1 year’s filling. These phenomena were mostly caused by the complexity, diversity, and inhomogeneity of EMCW. According to the proposed control standards of settlement and lateral deformation, as a method of foundation treatment, EMCW was an effective way to build a large piled mountain on soft soil foundation.

Optimization of Dynamic Load Carrying Capacity of Deep Groove Ball Bearing Using Jaya Algorithm

The design parameters have its impact on the quality of the components produced. To achieve the customer demands and survival in the competitive market, the need of the optimization of design parameters has become essential. In the present work, deep groove ball bearing is selected and the dynamic load capacity of it is to be optimized. The objective function is to maximize dynamic load capacity with design parameters bearing pitch diameter, the ball diameter, number of rolling elements and inner and outer-race groove curvature coefficients. The advanced optimization technique like Jaya algorithm is selected for the optimization of deep groove ball bearing. The results of selected algorithm are compared with the values obtained from genetic algorithm and it is observed that the selected optimization technique gives the better solution than the genetic algorithm.

Self-organized surface ripple pattern formation by ion implantation

Ion induced ripple pattern formation on solid surfaces has been extensively studied in the past and the theories describing curvature dependent ion erosion as well as redistribution of recoil atoms have been very successful in explaining many features of the pattern formation. Since most experimental studies use noble gas ion irradiation, the incorporation of the ions into the films is usually neglected. In this work we show that the incorporation or implantation of non-volatile ions also leads to a curvature dependent term in the equation of motion of a surface height profile. The implantation of ions can be interpreted as a negative sputter yield; and therefore, the effect of ion implantation is opposite to the one of ion erosion. For angles up to about 50°, implantation of ions stabilizes the surface, whereas above 50°, ion implantation contributes to the destabilization of the surface. We present simulations of the curvature coefficients using the crater function formalism and we compare the simulation results to the experimental data on the ion induced pattern formation using non-volatile ions. We present several model cases, where the incorporation of ions is a crucial requirement for the pattern formation.

Effects of disturbed landforms on the soil water retention function during urbanization process in the Three Gorges Reservoir Region, China

Decreases in the water retention function of various artificial disturbed landform units (DLUs) caused by urbanization activities, compared to original landform units (OLUs), are the main factor that causes urban water and soil loss and the aggravation of urban floods under certain rainfall conditions and specially designed drainage network capabilities. Field investigations, laboratorial analyses of soil physical properties and analytic hierarchy process (AHP) composite methods were performed to comprehensively analyse the effects of various DLUs on the water retention function of OLUs. The results indicated as the following: (і) The >5mm particle content (>54%) for various DLUs was higher than that for OLUs (lower than 3%); the natural repose angles of soil-rock mixtures (32–37°) and soil bulk density (1.41–1.74g/cm3) in the DLUs were all higher than those in the OLUs (30–31°, 1.18–1.14g/cm3); and the uniformity coefficients and curvature coefficients were 10.00–80.00 and 3.24–5.70 in the DLUs and 6.00–75.00 and 0.17–2.50 in the OLUs, respectively. (ii) The soil steady state infiltration rate in the DLUs decreased from disturbed soil accumulation with 2months (DSA2m, 15.00mm/min) to disturbed soil accumulation with 2years (DSA2a, 5.63mm/min), disturbed soil accumulation with 4years (DSA4a, 3.82mm/min), the slope greening belt (SGB, 1.24mm/min), and construction roads (CR, 0.51mm/min). The conversion from forests to DSA2m had the greatest impact on the soil infiltration capacity and soil storage capacity, while the conversion to CR had the lowest impact. (iii) The total reservoir storage in the DLUs' soil was ordered as follows: DSA4a>SGB>DSA2a>DSA2m>CR. The conversion process from grass to CR exerted the greatest impact on storing water and regulating the overland flow. (iv) The water retention functions in the DLUs were all weaker than those in the OLUs: DSA2m was the weakest (0.287), while paddy fields were the strongest (0.668). Thus, the occupied areas of urban water surfaces (e.g., lakes, rivers and ponds), forests and grassland and their spatial distribution during urbanization must be carefully considered. These results could help to understand the ecological service functions of urban soil and water conservation, provide relevant knowledge to landscape rehabilitation, alleviate urban floods during urban development and recover the functions of soil and water conservation ecological services in project areas during the urbanization construction process.

Argon ion beam induced surface pattern formation on Si

The development of self-organized surface patterns on Si due to noble gas ion irradiation has been studied extensively in the past. In particular, Ar ions are commonly used and the pattern formation was analyzed as function of ion incidence angle, ion fluence, and ion energies between 250 eV and 140 keV. Very few results exist for the energy regime between 1.5 keV and 10 keV and it appears that pattern formation is completely absent for these ion energies. In this work, we present experimental data on pattern formation for Ar ion irradiation between 1 keV and 10 keV and ion incidence angles between 50° and 75°. We confirm the absence of patterns at least for ion fluences up to 1018 ions/cm2. Using the crater function formalism and Monte Carlo simulations, we calculate curvature coefficients of linear continuum models of pattern formation, taking into account contribution due to ion erosion and recoil redistribution. The calculations consider the recently introduced curvature dependence of the erosion crater function as well as the dynamic behavior of the thickness of the ion irradiated layer. Only when taking into account these additional contributions to the linear theory, our simulations clearly show that that pattern formation is strongly suppressed between about 1.5 keV and 10 keV, most pronounced at 3 keV. Furthermore, our simulations are now able to predict whether or not parallel oriented ripple patterns are formed, and in case of ripple formation the corresponding critical angles for the whole experimentally studied energies range between 250 eV and 140 keV.