3D image reconstruction with a controllable overlapping number of elemental images in computational integral imaging

In this Letter, we propose a three-dimensional （3D） image reconstruction method with a controllable overlapping number of elemental images in computational integral imaging. The proposed method can control the overlap- ping number of pixels coming from the elemental images by using the subpixel distance based on ray optics between a 3D object and an image sensor. The use of a controllable overlapping number enables us to provide an improved 3D image visualization by controlling the inter-pixel interference within the reconstructed pixels. To find the optimal overlapping number, we simulate the pickup and reconstruction processes and utilize the numerical reconstruction results using a peak signal-to-noise ratio （PSNR） metric. To demonstrate the feasibility of our work in optical experiments, we carry out the preliminary experiments and present the results.

Modular construction mechanics of a European pressurized reactor steel containment liner

A European pressurized reactor （EPR） steel containment liner structure is comprised of the cylinder part and the dome part. An introduction of the steel liner structure is presented, followed by studies on the key mechanical features of the construction process using a refined finite element method. The steel liner was divided into several modules and then assembled during construction. Firstly, the equipment structure used to hoist the liner module was optimized, the lifting lug was analyzed using a multi-scale finite element model; the wind speed limit during lifting was also studied. Subsequently, the effect of internal forces during assembly between the liner modules, the lateral pressure of fresh concrete, the non-uniform temperature load, and the wind load on the cylinder module was analyzed. According to the time-varying structural performance during continuous concrete pouring and the hardening construction, an ＂overlapping element and birth-death element＂ technique was adopted to analyze the deformation and stress of the long-span steel dome liner. In addition, the stability-bearing capacities of the dome structure during construction were also studied, which took into consideration the effect of the initial geometrical imperfections and the elasto-plasticity of the material. This study presents a reference in terms of the mechanics of the construction scheme and the safety of such a type of structure.

A study on adjusted contact force laws for accelerated large scale discrete element simulations

The aim of this work is to systematically investigate the effect of the normal force law and the applied stiff- ness on the behavior of single particles and particle systems. A detailed review of the literature regarding altered stiffnesses and their use in force laws is provided, The effect on macroscopic simulation properties such as contact numbers, velocity profiles, discharge rates and quality of dispersion for different fractions of maximum overlap is studied in the case of a stirrer vessel and a rectangular hopper. In order to provide further acceleration beyond the limits imposed by classical force models, a number of alternative force laws are developed which have a more favorable ratio between contact time and maximal overlap. Their employment in large scale simulations is investigated in light of their applicability. Some of the suggested force law modifications reveal artificial characteristics requiring further alteration. 2009 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.