Shot Shape Research Articles

Shot noise processes with randomly delayed cluster arrivals and dependent noises in the large-intensity regime

AbstractWe study shot noise processes with cluster arrivals, in which entities in each cluster may experience random delays (possibly correlated), and noises within each cluster may be correlated. We prove functional limit theorems for the process in the large-intensity asymptotic regime, where the arrival rate gets large while the shot shape function, cluster sizes, delays, and noises are unscaled. In the functional central limit theorem, the limit process is a continuous Gaussian process (assuming the arrival process satisfies a functional central limit theorem with a Brownian motion limit). We discuss the impact of the dependence among the random delays and among the noises within each cluster using several examples of dependent structures. We also study infinite-server queues with cluster/batch arrivals where customers in each batch may experience random delays before receiving service, with similar dependence structures.

Functional limit theorems for a new class of non-stationary shot noise processes

We study a class of non-stationary shot noise processes which have a general arrival process of noises with non-stationary arrival rate and a general shot shape function. Given the arrival times, the shot noises are conditionally independent and each shot noise has a general (multivariate) cumulative distribution function (c.d.f.) depending on its arrival time. We prove a functional weak law of large numbers and a functional central limit theorem for this new class of non-stationary shot noise processes in an asymptotic regime with a high intensity of shot noises, under some mild regularity conditions on the shot shape function and the conditional (multivariate) c.d.f. We discuss the applications to a simple multiplicative model (which includes a class of non-stationary compound processes and applies to insurance risk theory and physics) and the queueing and work-input processes in an associated non-stationary infinite-server queueing system. To prove the weak convergence, we show new maximal inequalities and a new criterion of existence of a stochastic process in the space D given its consistent finite dimensional distributions, which involve a finite set function with the superadditive property.

RECONSTRUCTION OF SCAFFOLDING COMPONENTS FROM PHOTOGRAMMETRIC POINT CLOUDS OF A CONSTRUCTION SITE

Abstract. This paper presents a data-driven workflow for the detection of scaffolding components from point clouds. The points belonging to the scaffolding components are identified and separated from the main building structures and two basic elements, namely the toeboard and the tube, are reconstructed. The workflow has four main processing steps. Firstly, the raw point clouds are preprocessed by statistical filtering and voxel girding. In the second step, the planar surfaces of the building surface and scaffoldings are extracted via RANSAC and then grouped by their parallelity and distance to separate the building façade. In the third step, the 3D shape descriptor FPFH and random forest classification algorithm are applied to classify the point data of building façades into classes belonging to different elements. Finally, by the use of linear fitting algorithm and matching using SHOT shape descriptor, the tubes and toeboards are reconstructed with their geometric parameters. It is shown that the points belonging to these objects are identified and then reconstructed with cylinder and cuboid models. The final results show that over 60% of the tubes and nearly 90% of the toeboards are reconstructed in the investigated façade, and more than 40% of the reconstructed objects are well rebuilt.

Calculation and Analysis of 2-D Thermal Stress Field in Induction Motor with Compound Cage Rotor under Different Load

3kW two poles induction motor with compound cage rotor is illustrated in this paper, and 2-D thermal stress field of induction motor rotor is calculated and analyzed by finite element. Contrasting with common induction motor, induction motor with compound cage rotor has specific rotor shot shape and the bar is comprised of the upper compound material and the lower cast aluminium, which cause distribution of thermal stress is special. The motor with the rotor shot of compound material laid at single site is chosen to analyzing. The maximum thermal stress in the bar is calculated at different load, and the distribution of thermal stress in the bar is analyzed at rate load. The law of distribution of thermal stress in the bar has same reference value for designing new type of induction motor.

Sample Path Large Deviations of Poisson Shot Noise with Heavy-Tailed Semiexponential Distributions

It is shown that the sample paths of Poisson shot noise with heavy-tailed semiexponential distributions satisfy a large deviation principle with a rate function that is insensitive to the shot shape. This demonstrates that, on the scale of large deviations, paths to rare events do not depend on the shot shape.

Sample Path Large Deviations of Poisson Shot Noise with Heavy-Tailed Semiexponential Distributions

It is shown that the sample paths of Poisson shot noise with heavy-tailed semiexponential distributions satisfy a large deviation principle with a rate function that is insensitive to the shot shape. This demonstrates that, on the scale of large deviations, paths to rare events do not depend on the shot shape.

Determination of Shot Peening Coefficient of Restitution

To characterise an impact between two solids, a coefficient of restitution is generally used er equal to 1 when the impact is perfectly elastic, 0 when the impact is totally plastic and between 0 and 1 when the impact is elastic - plastic. For the shot peening surface treatment process, this coefficient, which is linked to the shot hardness/ material hardness ratio, is of interest for two reasons. First, to characterise the distribution of the stream energy produced by an impact (stream energy = energy of the induced plastic deformations in the used shot and in the treated material + elastic energy + dissipated energy into vibrations etc.). Two, to compare the efficiency of different types (material, hardness, size and shape) of shot. The coefficient of restitution er can be introduced to an existing shot peening model. The present paper gives a theoretical analysis of the distribution of the different energies during the shot peening process and describes an experimental investigation to determine the values of the coefficient of restitution for four principal types of shot; three in cast steel: cut wire Fil Coupé (F.C.) 0.6 mm and WS280 with two hardness values: 48 and 58 HRC, and one in low carbon cast steel:F16. The target was 13% manganese steel sheet with a hardness of 60 HRC. Results of the different coefficients of restitution were noted for each type of shot and the values obtained were presented and discussed. They show reasonable agreement with the theoretical analysis. It has been observed that the coefficient of restitution is principally linked to the shot hardness, material hardness ratio and the shot shape.

Noise variability of the hard X-ray transient Nova Persei

view Abstract Citations (9) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Noise Variability of the Hard X-Ray Transient Nova Persei Denis, M. ; Olive, J. -F. ; Mandrou, P. ; Roques, J. P. ; Ballet, J. ; Goldwurm, A. ; Laurent, Ph. ; Cordier, B. ; Vikhlinin, A. ; Churazov, E. ; Gilfanov, M. ; Sunyaev, R. ; Dyachkov, A. ; Khavenson, N. ; Kremnev, R. ; Kovtunenko, V. Abstract The hard X-ray transient Nova Persei (GRO J0422+32) was observed with the SIGMA telescope continuously for 2 months, soon after its discovery in 1992 August. The temporal analysis of the 40-300 keV emission of this source showed a very high level of noise variability (approximately 20%). Such variability has previously only been observed at hard X-ray/soft gamma-ray energies from an accreting X-ray source, in the case of the black hole candidate Cygnus X-1. The Fourier power distribution in the 2 x 10-4 -1.25 x 10-1 Hz range is flat up to a break frequency (approximately 0.03 Hz) and then steepens to a power law with an index of approximately -0.8 around 0.1 Hz. These results can be interpreted in terms of the shot noise model. The photons in the shots represent a significant fraction (approximately 20%) of the source hard X-ray flux. The derived shot duration range from approximately to a few seconds, depending on the shot shape. The shot shape and duration do not show any correlation with the hard X-ray source flux, as the spectral shape did not apparently evolve during the outburst, so probably they are only weakly correlated with the accretion rate. While the source flux decreased uniformly from around 3 to 1 Crab unit in the period 1992 August 15 until September 25, the fractional integrated root mean square variability increased from about 15% to 30%. We have studied this correlation with the help of a 'source total flux-source noise flux' diagram which reveals a regular but rather complex dependence with at least three different regimes. Publication: The Astrophysical Journal Supplement Series Pub Date: June 1994 DOI: 10.1086/191996 Bibcode: 1994ApJS...92..459D Keywords: Black Holes (Astronomy); Gamma Ray Astronomy; Novae; X Ray Sources; Accretion Disks; Flux (Rate); Fourier Analysis; Power Spectra; Transient Oscillations; Astronomy full text sources ADS | data products SIMBAD (2) HEASARC (1)