Digital Rock Physics (DRP) has three major steps: 1) Image acquisition using Xray microCT, FIBSEM etc., 2) Image processing and model creation and 3) numerical simulation. A Finite Element Method (FEM) was used to simulate linear, isotropic elastic properties in sandstones quite successfully but carbonate elastic property predictions remain challenging. In this paper the effect of imaging resolution on elastic property predictions for this FEM were studied. Two approaches were tested:1) through digital resampling of resolution of the same 3D image and 2) through real multiresolution imaging of the same region using Xray microCT.
Computational fluid dynamics (CFD) has been used to evaluate the role of highly conductive spacers on the performance of a direct contact membrane distillation (DCMD) system. The numerical model assumes a 2D steady state, conjugated heat, and laminar NavierStokes flow. Mass flux is estimated by integrating a combined Knudsen and Poiseuille flow model. The effect of adding conductive and nonconductive spacers on temperature polarization coefficient, mass flux and thermal efficiency has been investigated at different Re numbers. Results showed that copper spacers showed better performance than polymer spacers, but a significant enhancement was not observed from the no spacer case. Only at Re 10, the copper spacer contributed to a 3% gain in TPC and a 1% gain in each mass flux and thermal efficiency of the process.
A nonpressurized gravity offshore intake pipeline is made from a polypropylene block copolymer and used to transport a seawater for petrochemical process plant. Recently, a few premature failures have been reported in the field. Therefore, there is a need to characterize the constitutive behavior and the failure locus of the pipe and the weld joint material. The uniaxial tensile test experiments show that the pipe material has about twice higher yield strength than the weld material and it has strain rate dependency. Based on those experiments, a simple analytical constitutive material model can be developed for finite element analysis (FEM). The failure locus is determined by a combination of FEM and an experiment of notched dumbbell specimens. Finally, the constitutive model and the failure loci for both materials are implemented in a FEM and validated by conducting a series of independent fourpoint bend experiment, which shows a rather good agreement.
The energy requirement for cooling systems is dramatically increasing for controllable and noncontrollable reasons. Thermal energy storage (TES), is a method integrated with a chiller cooling system to eliminate the leap and smoothening the fluctuations in the cooling load curve. Results show a promising energy saving conducted through introducing a cooling load for two experimentbased models with and without TES, illustrating the advantages of TES. Exergy analysis is performed to ensure the outputs of the two models
With the development of modern industry, the separation of suspended particles from the gaseous flow becomes increasingly important. Many industrial applications need to control the concentration of fine liquid droplets in moving gaseous mediums in order to ensure the system work normally and efficiently, such as refrigeration and Heating Ventilation Air Conditioning (HVAC) systems. Electrostatic Precipitator (ESP) can be adopted for separation of fine droplets in gas, since corona discharge could charge these particles, then use of electrostatic force to implement separation and collection. Current works are mainly studying key parameters which affect separation efficiency, such as applied voltage, temperature, flow velocity and particle's size. The corona discharge ionization will be applied in this process.
Memristorbased inmemory computing is gaining an increased attention as a potential candidate to overcome the traditional von Neumann bottleneck. It combines both storage and computation processes within the same physical element. The nonvolatility nature of memristor analog behaviour, nanoscale size and high resistance ratio are some of its key features. Furthermore, the continuous response of memristor state variable to an applied input voltage makes it ideal candidate for multiply and accumulate operation found in many digital signal processing tasks. The crossbar architecture is inherently parallel, and can serve as an accelerator to speedup the vector matrix operation with potential savings in energy, area and execution time. However, the presence of sneak path current, state drift and lack of conductance controllability are some of the issues hindering the adoption of memristors in largescale networks. In this paper, an overview of a memristorbased multiplyaccumulate architecture with current limitations are discussed.
Autonomous bionic systems are ultralow power systems with low data rate operation. Most healthcare bionic systems that are implantable in the human body utilize MEMS technology. The conventional solution of powering such systems using batteries is not practical as battery charging or replacement may not be feasible or desirable. As such, the need to explore new solutions in order to increase lifetime and achieve autonomous operation is fueling the energy scavenging research. This paper presents a study of magnetic and piezoelectric energy harvesting and their suitability for autonomous bionic systems. A study of stateofthe art magnetoelectricpiezoelectric transducers used in biomedical systems is presented. Our study revealed that integrating magnetostriction and piezoelectric effects in a single transducer significantly increases the harvested voltage by 2x and increases the total efficiency of the harvesting system. As such, integrating magnetostrictive and piezoelectric materials in energy harvesters provides a promising solution for autonomous bionic systems.
Nonlinear acoustic echo cancellation is important due to the increasing use of free hand mobile phone and conferences. To improve the quality of the communication methods, many techniques have been developed recently. This paper discusses different types of adaptive filter models to eliminate nonlinear acoustic echo which are functional link adaptive filter (FLAF) model, propitiate FLAF, Empirical Mode Decomposition (EMD)based subband adaptive filtering structure, collaborative FLAF based on RLS algorithm and variational Bayesian statespace frequencydomain adaptive filter (VBSSFDAF) . All previous algorithms depend on the adaptive filters and to divide the signals into subgroups signal using different techniques. These algorithms have been successfully tested to eliminate various nonlinearity echoes under different conditions and the results were assessed.
In this paper, identification of fractional Wiener system using particle swarm methodology is presented. It consists of a linear part followed by a static nonlinear block. For this purpose the key term principle is used, and the parameters of the linear and the nonlinear part of the Wiener system as well as the fractional order are estimated. To show the efficiency of this approach, a simulation example is considered for different signal to noise ratios.
We present an integrated strategy for buildings extraction in very high resolution satellite imagery of urban areas. Buildings are extracted using structural, contextual, and spectral information. First, we use OneClass support vector machine (SVM) in order to determine the manmade structures (buildings, roads, etc.) after performing segmentation based on multiresolution and spectral difference. Next, we proceed with texture segmentation approach using a conditional threshold value to extract the buildings. And then, we use geodesic opening and closing operations to extract bright foreground objects. After this, shadows and vegetation regions are detected in these segments based on their spectral properties. Finally, we classify the buildings after removal of noises by checking for the presence of shadows along the buildings opposite to the suns azimuth direction to distinguish buildings from other bright regions. Performance evaluation of the proposed algorithm is performed on data acquired using WorldView satellite imagery over Abu Dhabi.
