Predicting crystal structure by merging data mining with quantum mechanics

Modern methods of quantum mechanics have proved to be effective tools to understand and even predict materials properties. An essential element of the materials design process, relevant to both new materials and the optimization of existing ones, is knowing which crystal structures will form in an alloy system. Crystal structure can only be predicted effectively with quantum mechanics if an algorithm to direct the search through the large space of possible structures is found. We present a new approach to the prediction of structure that rigorously mines correlations embodied within experimental data and uses them to direct quantum mechanical techniques efficiently towards the stable crystal structure of materials.     

Predicting of bead undercut defects in high-speed gas metal arc welding (GMAW)

In the gas metal arc welding (GMAW) process, when the welding speed reaches a certain threshold, there will be an onset of weld bead undercut defects which limit the further increase of the welding speed. Establishing a mathematical model for high-speedGMAWto predict the tendency of bead undercuts is of great significance to prevent such defects. Under the action of various forces, the transferred metal from filler wire to the weld pool, and the geometry and dimension of the pool itself decide if the bead undercut occurs or not. The previous model simplified the pool shape too much. In this paper, based on the actual weld pool geometry and dimension calculated from a numerical model, a hydrostatic model for liquid metal surface is used to study the onset of bead undercut defects in the high-speed welding process and the effects of different welding parameters on the bead undercut tendency.     

Thermodynamics of the hygroscopic state of disperse materials

Expressions of the analytical dependences of the specific isothermal mass capacity and thermal gradient coefficient on moisture content and temperature for disperse materials in a hygroscopic state are found on the basis of the expression of the chemical potential and B. A. Posnov's formula.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 20, No. 3, pp. 481–487, March, 1971.     

Predicting of bead undercut defects in high-speed gas metal arc welding (GMAW)

In the gas metal arc welding (GMAW) process, when the welding speed reaches a certain threshold, there will be an onset of weld bead undercut defects which limit the further increase of the welding speed. Establishing a mathematical model for high-speed GMAW to predict the tendency of bead undercuts is of great significance to prevent such defects. Under the action of various forces, the transferred metal from filler wire to the weld pool, and the geometry and dimension of the pool itself decide if the bead undercut occurs or not. The previous model simplified the pool shape too much. In this paper, based on the actual weld pool geometry and dimension calculated from a numerical model, a hydrostatic model for liquid metal surface is used to study the onset of bead undercut defects in the high-speed welding process and the effects of different welding parameters on the bead undercut tendency.     

Automatic merging of tetrahedral meshes

A generic algorithm is proposed to merge arbitrary solid tetrahedral meshes automatically into one single valid finite element mesh. The intersection segments in the form of distinct nonoverlapping loops between the boundary surfaces of the given solid objects are determined by the robust neighbor tracing technique. Each intersected triangle on the boundary surface will be triangulated to incorporate the intersection segments onto the boundary surface of the objects. The tetrahedra on the boundary surface associated with the intersected triangular facets are each divided into as many tetrahedra as the number of subtriangles on the triangulated facet. There is a natural partition of the boundary surfaces of the solid objects by the intersection loops into a number of zones. Volumes of intersection can now be identified by collected bounding surfaces from the surface patches of the partition. Whereas mesh compatibility has already been established on the boundary of the solid objects, mesh compatibility has yet to be restored on the bounding surfaces of the regions of intersection. Tetrahedra intersected by the cut surfaces are removed, and new tetrahedra can be generated to fill the volumes bounded by the cut surfaces and the portion of cavity boundary connected to the cut surfaces to restore mesh compatibility at the cut surfaces. Upon restoring compatibility on the bounding surfaces of the regions of intersection, the objects are ready to be merged together as all regions of intersection can be detached freely from the objects. All operations, besides the determination of intersections structurally in the form of loops, are virtually topological, and no parameter and tolerance is needed in the entire merging process. Examples are presented to show the steps and the details of the mesh merging procedure. Copyright © 2012 John Wiley & Sons, Ltd.     

Water permeability of disperse systems

The interrelation between structure-sorption characteristics and the water permeability of ion-substituted forms of clay minerals is investigated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol.19, No.2, pp.229–235, August, 1970.     

Vibration-extrusion discharge of disperse systems

The physical principles governing the vibration-extrusion discharge of disperse systems are discussed. The criterion for optimizing this process is obtained and methods for achieving it are indicated.Paper presented at the Seventh Symposium on the Rheology of Polymers, Moscow, April 10–14 (1972).Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 2, pp. 221–227, February. 1976.     

Rheological effect in the filtration of disperse systems

An experimental and theoretical study is made of the effect of the viscoelastic properties of disperse systems on their filtration rate.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 3, pp. 419–424, September, 1989.     

Heat and mass transfer between the disperse phase and the carrying medium in a plane turbulent disperse near-wall jet

Heat and mass transfer in a liquid-liquid and liquid-solid medium are investigated theoretically and experimentally in a jet heat- and mass-transfer apparatus.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 6, pp. 897–904, June, 1988.     

Calculation of the drying of a disperse polyfractional system

A method is presented for the calculation of the time required to dry disperse polyfractional ceramic suspensions with a high initial content of the solid phase.     

The theory of the rheological properties of disperse systems

The effective rheological characteristics of stacking identical viscoelastic spheres in a matrix of another viscoelastic material are estimated by methods of ensemble averaging theory.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 58, No. 5, pp. 721–729, May, 1990.     

Stability of roughly disperse vertical flows

Conditions have been found for neutral stability of vertical flows of suspended large particles. Characteristics of disturbances with a maximum growth increment in the instability region are considered.Ural State University, Ekaterinburg, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 4, pp. 542–551, July–August, 1995.     

A stochastic model of disperse systems

We suggest a model of the structure of a disperse system that reflects the random character of the topology. We evaluate the effect of the stochastic nature of the topology on the effective conductivity. An asymptotic decrease in the conductivity with increase in the scale of the heat and mass transfer is established and explained.     

Thermoelastic effects in disperse systems

We devised a continual theory of the thermoelasticity of a disperse medium consisting of a homogeneous matrix with spherical inclusions of some other material distributed in it.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 51, No. 2, pp. 248–255, August, 1986.     

In-depth analysis of drivers’ merging behavior and rear-end crash risks in work zone merging areas

This study investigates the drivers’ merging behavior and the rear-end crash risk in work zone merging areas during the entire merging implementation period from the time of starting a merging maneuver to that of completing the maneuver. With the merging traffic data from a work zone site in Singapore, a mixed probit model is developed to describe the merging behavior, and two surrogate safety measures including the time to collision (TTC) and deceleration rate to avoid the crash (DRAC) are adopted to compute the rear-end crash risk between the merging vehicle and its neighboring vehicles. Results show that the merging vehicle has a bigger probability of completing a merging maneuver quickly under one of the following situations: (i) the merging vehicle moves relatively fast; (ii) the merging lead vehicle is a heavy vehicle; and (iii) there is a sizable gap in the adjacent through lane. Results indicate that the rear-end crash risk does not monotonically increase as the merging vehicle speed increases. The merging vehicle's rear-end crash risk is also affected by the vehicle type. There is a biggest increment of rear-end crash risk if the merging lead vehicle belongs to a heavy vehicle. Although the reduced remaining distance to work zone could urge the merging vehicle to complete a merging maneuver quickly, it might lead to an increased rear-end crash risk. Interestingly, it is found that the rear-end crash risk could be generally increased over the elapsed time after the merging maneuver being triggered.     

Evolution of the microstructure of disperse Zinc-oxide during tribophysical activation

The process of macro- and microstructural transformations of zinc-oxide powders, which were tribophysically activated by grinding in a vibro-mill was investigated using methods of transmission electron microscopy, infrared spectroscopy and X-ray. It is shown that tribophysical activation contributes to a gradual modification of the fine defect structure of zinc-oxide powders. In the starting stage agglomerates and bigger, longer particles are destroyed first of all. As a result of the formation of both volume and surface defects and changes of the character of interparticles interactions the plate-like polycrystal particles are created. They actually present sets of coherent scattering region.     

Kinetics and dynamics of the conductive drying of disperse materials

An analysis is given of the effect of certain parameters on the intensity and rate of conductive drying, the results are generalized in the form U = f(N₁/u₀), , and information is given for the thermal calculation of the process.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 36, No. 6, pp. 1004–1011, June, 1979.     

Allowing for correlation in the investigation of dense disperse media

Exact coupled relations have been obtained for the first two statistical moments of an electromagnetic field in a randomly heterogeneous disperse medium. The moments are used to formulate approximate Dyson and Bethe-Salpeter equations that allow for correlations of all orders between the particles of the medium. These approximate equations serve as a basis for the development of methods and instruments for measuring the parameters of disperse media and the exact coupled relations provide an estimate of their accuracy.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 5–7, April, 1994.This work was carried out partially within the scope of project No. 4188 F of the Russian Ministry of Science of December 10, 1992.