Light curve and orbital elements of V 337 Aquilae     

F. A. Catalano  S. Catalano  M. Rodonò 《Astrophysics and Space Science》1971,11(2):232-243

From photoelectric observations of V 337 Aql a new solution is carried out. Transit at primary eclipse in disagreement with the Wright-Dugan results is found. Both Russell-Merrill and Kitamura methods of light curve solution are used. The slight period variation and the distortions of the light curve would support the idea that a mass exchange could be in act.  相似文献   

Convection in a rotating deep compressible spherical shell: Application to the Sun     

Gaetano Belvedere  Lucio Paternò 《Solar physics》1977,54(2):289-312

In this paper we study the interaction of rotation with convection in a deep compressible spherical shell as the Sun's convection zone. We examine how the energy transport and the large scale motions can be affected by rotation. In particular we study how a large scale meridional circulation can give rise to variations of angular velocity with latitude and depth.It is assumed that the energy transport is only due to convection and that the mixing-length theory gives an adequate representation of it. Furthermore we assume that rotation acts as a perturbation of the turbulent convective flux through its transport coefficient.The equations involved in the model are integrated numerically in the limit of large viscosity and slow rotation. After having expanded all physical quantities to the first order in terms of Legendre polynomials, the fitting with the observed solar differential rotation gives the expansion parameter, which represents the coupling constant between rotation and convection.The results show a three-cell circulation extending from the poles to the equator. The first one is located in the lower half of the convection zone with the fluid rising at the equator and sinking at the poles. In the second one the direction of the motion is reversed while the third one, located in a thin upper layer, shows the same characteristics of the first one. The meridional velocities at the surface are directed towards the poles and are about 20 cm s^-1. In the other cells the meridional velocities are typically of a few cm s^-1 while the radial velocities are of the order of a few tenths of cm s^-1.The heat flux relative variation at the surface is about 10^-4 (3 × 10^-3 at the bottom) with a polar excess. The temperature variation at the surface is of the same order, with an equatorial excess however. The convection seems to be stabilized stronger at the equator. The angular velocity increases inwards and varies about 6% between the surface and the bottom of the convection zone.An attempt is made for explaining the picture which emerges. In particular the negligible flux and temperature variations at the surface are explained in terms of equalization by the particular structure of the latitudinal flow. This configuration of large scale circulation is attributed to the high stratification of the convection zone with depth.  相似文献   

Surface Reynolds stresses determined from the analysis of facular motions and the maintenance of the Sun's differential rotation     

G. Belvedere  G. Godoli  S. Motta  L. Paternò  R. A. Zappalà 《Solar physics》1976,46(1):23-28

From the analysis of the motions of faculae for a four year period from 1967 to 1970, the latitudinal angular momentum transport by Reynolds stresses at the Sun's surface is calculated. The result agrees fairly well with the one obtained by Ward analyzing spot motions. A comparison with theory suggests that the Sun's differential rotation could be maintained only by Reynolds stresses at the surface. The implications of this result are discussed.  相似文献   

Report on the VIII Hotine Symposium on Mathematical Geodesy     

Fernando Sansò 《Journal of Geodesy》1982,56(2):177-179

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Simulation of the Steady-State Flow in Discrete Fracture Networks with Non-Conforming Meshes and Extended Finite Elements     

S. Berrone  C. Fidelibus  S. Pieraccini  S. Scialò 《Rock Mechanics and Rock Engineering》2014,47(6):2171-2182

In this paper a numerical method for the simulation of the steady-state fluid flow in discrete fracture networks is described. It is based on the use of non-conforming meshes, enrichment functions and an optimization procedure. The meshing process is performed on each fracture independently of the other fractures, i.e. without geometrical conformity at the intersections (traces). The slope discontinuities due to the flux exchange at the traces are then captured with the enrichment functions of the extended finite elements, and finally a functional is minimized by resorting to an optimization procedure. The method can be easily implemented for parallel computers being based on many small independent problems. In order to show the effectiveness of the method and the quality of the results, simulations of fluid flow in simple networks are illustrated.  相似文献   

Bonding degradation and stress–dilatancy response of weakly cemented sands     

Daniela D. Porcino  Vincenzo Marcianò 《Geomechanics and Geoengineering》2017,12(4):221-233

The progressive bond breakage of artificially cemented sands induced by shear straining was investigated through conventional isotropically consolidated drained triaxial compression tests. Sand specimens were prepared with a low degree of cementation by adopting a chemical grout. Test results were interpreted in terms of two stress–dilatancy theories for cohesive-frictional materials proposed in literature. The influence of debonding on the stress–dilatancy behaviour of cemented sands was analysed with particular emphasis on the ‘delayed dilatancy’ phenomenon. A bonding degradation curve was determined for each test relating the interparticle cohesion (c) to the magnitude of the total plastic strain vector (ε_d) and a bond degradation rate factor (D_c) was assessed from each curve. The maximum value of interparticle cohesion (c₀) before the onset of bond degradation under shearing was found to correspond with a sharp decrease in the soil stiffness of the specimens. The influence of the effective confining stress (p^′_c) on both c₀ and D_c parameters gathered from each test was also ascertained.  相似文献   

From computed tomography to mechanics of granular materials via level set bridge     

Ivan Vlahinić  Reid Kawamoto  Edward Andò  Gioacchino Viggiani  José E. Andrade 《Acta Geotechnica》2017,12(1):85-95

This paper details the ‘level set bridge’: a single platform for the characterization of various aspects of granular micro-mechanics, including grain morphology, grain kinematics, and inter-granular contact. This platform is studied and verified for accuracy using synthetic examples, in particular, its robustness with respect to the variables of image resolution and noise. The level set bridge is then applied to analysis of XRCT images of real 3D triaxial experiments of two types of granular materials. Contact statistics and kinematics are reported inside and outside of the failure band of one, and kinematics inside a failure band are reported in the other, from preload to critical state.  相似文献   

The effect of different intensity measures and earthquake directions on the seismic assessment of skewed highway bridges     

M. Bayat  F. Daneshjoo  N. Nisticò 《地震工程与工程振动(英文版)》2017,16(1):165-179

In this study the probable seismic behavior of skewed bridges with continuous decks under earthquake excitations from different directions is investigated.A 45° skewed bridge is studied.A suite of 20 records is used to perform an Incremental Dynamic Analysis(IDA) for fragility curves.Four different earthquake directions have been considered:-45°, 0°, 22.5°, 45°.A sensitivity analysis on different spectral intensity measures is presented; efficiency and practicality of different intensity measures have been studied.The fragility curves obtained indicate that the critical direction for skewed bridges is the skew direction as well as the longitudinal direction.The study shows the importance of finding the most critical earthquake in understanding and predicting the behavior of skewed bridges.  相似文献   

A new macromodel for the assessment of the seismic response of infilled RC frames     

Bartolomeo Pantò  Pier Paolo Rossi 《地震工程与结构动力学》2019,48(7):792-817

Numerous research studies have proved that numerical models aiming at an accurate evaluation of the seismic response of RC framed buildings cannot ignore the inelastic behaviour of infills and the interaction between infill and frame elements. To limit the high computational burden of refined non-linear finite element models, in the latest decades, many researchers have developed simplified infill models by means of single or multiple strut-elements. These models are low time-consuming and thus adequate for static and dynamic analyses of multi-storey structures. However, their simulation of the seismic response is sometimes unsatisfying, particularly in the presence of infill walls with regular or (particularly) irregular distributions of openings. This paper presents a new 2D plane macro-element, which provides a refined simulation of the non-linear cyclic response of infilled framed structures at the expense of a limited computational cost. The macro-element consists of an articulated quadrilateral panel, a single 1D diagonal link, and eight 2D links and is able to model the shear and flexural behaviour of the infill and the non-linear flexural/sliding interaction between infill and surrounding frame. The proposed macro-element has been implemented into the open source software OpenSees and used to simulate the response of single-storey, single-span RC infilled frame prototypes tested by other authors. The above prototypes are selected as made of different masonry units and characterised by full or open geometric configuration.  相似文献