Seismic data interpolation without iteration using t-x-y streaming prediction filter with varying smoothness

Although there is an increase in the amount of seismic data acquired with wide-azimuth geometry, it is difficult to achieve regular data distributions in spatial directions owing to limitations imposed by the surface environment and economic factor. To address this issue, interpolation is an economical solution. The current state of the art methods for seismic data interpolation are iterative methods. However, iterative methods tend to incur high computational cost which restricts their application in cases of large, high-dimensional datasets. Hence, we developed a two-step non-iterative method to interpolate nonstationary seismic data based on streaming prediction filters (SPFs) with varying smoothness in the time-space domain; and we extended these filters to two spatial dimensions. Streaming computation, which is the kernel of the method, directly calculates the coefficients of nonstationary SPF in the overdetermined equation with local smoothness constraints. In addition to the traditional streaming prediction-error filter (PEF), we proposed a similarity matrix to improve the constraint condition where the smoothness characteristics of the adjacent filter coefficient change with the varying data. We also designed non-causal in space filters for interpolation by using several neighboring traces around the target traces to predict the signal; this was performed to obtain more accurate interpolated results than those from the causal in space version. Compared with Fourier Projection onto a Convex Sets (POCS) interpolation method, the proposed method has the advantages such as fast computational speed and nonstationary event reconstruction. The application of the proposed method on synthetic and nonstationary field data showed that it can successfully interpolate high-dimensional data with low computational cost and reasonable accuracy even in the presence of aliased and conflicting events.

Detecting Regime Transitions of the Nocturnal and Polar Near-Surface Temperature Inversion

Many natural systems undergo critical transitions, i.e., sudden shifts from one dynamical regime to another. In the climate system, the atmospheric boundary layer can experience sudden transitions between fully turbulent states and quiescent, quasi-laminar states. Such rapid transitions are observed in polar regions or at night when the atmospheric boundary layer is stably stratified, and they have important consequences in the strength of mixing with the higher levels of the atmosphere. To analyze the stable boundary layer, many approaches rely on the identification of regimes that are commonly denoted as weakly and very stable regimes. Detecting transitions between the regimes is crucial for modeling purposes. In this work a combination of methods from dynamical systems and statistical modeling is applied to study these regime transitions and to develop an early warning signal that can be applied to nonstationary field data. The presented metric aims to detect nearing transitions by statistically quantifying the deviation from the dynamics expected when the system is close to a stable equilibrium. An idealized stochastic model of near-surface inversions is used to evaluate the potential of the metric as an indicator of regime transitions. In this stochastic system, small-scale perturbations can be amplified due to the nonlinearity, resulting in transitions between two possible equilibria of the temperature inversion. The simulations show such noise-induced regime transitions, successfully identified by the indicator. The indicator is further applied to time series data from nocturnal and polar meteorological measurements.

Determination of nonstationary thermal field of passenger car wheel at braking

The paper is devoted to modeling of nonstationary field of a passenger car wheel at braking. The calculation is based on formulation of thermal conductivity equation for the wheel tread as a curved rod with the application of linear approximation of thermal field. At formulation of thermal conductivity equation it is necessary to consider a balance of heat in small volume of tread with the consideration for thermal flow from braking shoe, thermal emission to the environment and thermal conductivity in circular direction. The authors have set for the initial equation of thermal conductivity a functional and have formulated conditions of stationarity that leads after integration to the system of the first order differential equations of time. The authors have applied the Euler method at integration. The developed method has been realized in the C++ program. With the use of this application the authors have conducted a research of the thermal field of the passenger car wheel. The method can be used at designing of new rolling stock and for the analysis of reasons of flaws appearance on the surface of car wheels.

Method of Determination of Technological Durabilityof Plastically Deformed Sheet Parts of Vehicles

The purpose of the article is to develop an apparatus providing maximum or predicted durability of parts treated during their manufacture by plastic deformation. In these terms, the parameters of the technological process should provide the maximum or expected increase of the endurance limit in comparison with the initial parts values before the strengthening by the surface plastic deformation or after plastic forming. The article describes the influence of the degree of preliminary deformation on the kinetics of fatigue failure of metals and alloys. Experimental data of the ultimate deformations of welded workpieces were obtained, which make it possible to evaluate the manufacturing of parts with a weld seam at the design stage of the technological process. The developed method made it possible to determine the nonstationary field of stresses in the deformation region, ultimate deformations and the most rational scheme of the stress-strain state, which excludes the localization of deformations and destruction of the weld zone of a welded cylindrical workpieces.

Seepage Regime in Canyon Mass With Influence of Water-Storage Reservoir Impoundment Speed

Generally, most waterpower plants have to function under energy system peak load operation. Thus, there is a relatively quick water level variation observed in water-storage reservoirs, which contributes to the problems, especially in case of high-pressure waterworks facilities. Swift reservoir draw-down enhances seepage volumetric forces acting from the rock mass, which may lead to rock mass cracking and eventually to the development of landslide processes. A rapid impoundment of the water-storage reservoir is no less damaging. In this case, seepage in the rock mass is progressing in non-steady conditions, there occurring, in the inception stage: - high magnitude seepage hydrodynamic forces at the rock mass surface, creating additional loads on the rock mass, causing deflection of its surface, which may promote dam-foundation contact opening; - with increased pore pressures and seepage gradients, there may occur suffusion and other undesirable processes in the rock mass. In the work is given a numerical analysis of some parameters of seepage mode given based on right-bank investigation admitting presence of break in the dam filling-up mode. Options of time-intervals for the two basic versions – in case of sudden rising of water level in the upstream and in case of slow filling-up and setting up steady-state seepage mode in the massive – are being discussed. Determination of seepage flow parameters (including gradients) requires nonstationary field task to be solved. Finite-elements approximation for time analysis of the task is solved by finite-difference scheme. Seepage calculations are carried out by cyclic-iteration scheme – where volumetric water content, hydraulic conductivity and elasticity module determined numerically by functional relations. The subject of research is Enguri waterpower plant arch dam, at present the highest in the world (Georgia, height 271.5m, fig. 1.1). Consideration is being given to a variety of cases: - canyon slope in the zone of major geological fracture; - foundation in the central part of the dam.