Grid Dimensions Research Articles

Study on the Effect of Grid Column on Seismic Performance of Improved Multi-Ribbed Slab Structure

In order to confirm the calculation model of multi-ribbed slab structure and transmission of earthquake action, this paper improved existing multi-ribbed slab structure. The calculation model of improved multi-ribbed slab structure confirmed the stress relationship among three seismic fortification lines, and the transmission of earthquake action became clear, the same calculation model could be applied in structural analysis. For studying the effect of characteristic parameters of restoring force changing in the second seismic fortification line on seismic performance, and correcting the parameters, this paper analyze push-over model of the second seismic fortification line to get the static pushover curve. According to the study, the amount of steel bar in grid column and sectional dimensions of grid beam made the major effect on characteristic parameters of restoring force in the second seismic fortification line. The growth of steel bar’s sectional area in grid framework and the yield strength are mainly in direct proportion. It is more reasonable that simultaneously alter steel bar’s sectional area in grid frame and dimensions of grid framework to adjust characteristic parameters of restoring force changing in the second seismic fortification line.

Dimensioning of Energy Storage for Increased Integration of Wind Power

Energy storage can potentially allow for more production from renewable resources into existing grids. A methodology to quantify grid limitations and dimension battery energy storage systems is presented in this paper. By use of grid consumption and production data, the hosting capacity methodology is developed as a general framework for storage dimensioning that can be applied by grid operators. The method is successfully applied to an existing subtransmission grid; actual hourly production and consumption data during a two-year period is used. The role of a storage system compared to other means to handle overloading is studied. It is found that about one third of overloading instances are suitable to handle with a battery energy storage system. After this, diminishing returns per unit of storage capacity are shown to occur.

Numerical Simulation of Flow around Diamond-Shaped Obstacles at Low to Moderate Reynolds Numbers

In this paper, viscous fluid flow over an unconventional diamond-shaped obstacle in a confined channel is simulated in low to moderate Reynolds numbers. The diamond-shaped obstacle is altered geometrically in order to represent different blockage coefficients based on the channel height and different aspect ratios based on the length to height ratios of the obstacle. An in-house finite difference Navier-Stokes solver using staggered grid arrangement and Chorins projection method is developed for the simulation of the laminar viscous flow. The numerical solver is validated against numerical results that are presented in the literature for the flow over rectangular cylinders and good agreement is observed. Grid resolution has been studied within a mesh convergence test and as a result, suitable grid dimension is achieved. A series of simulations have been carried out for each set of geometry and configuration in order to find the critical Reynolds number for each case in which the vortex shedding will occur. Therefore, simulations are divided into two groups of steady and unsteady flows. In the case of unsteady flow, non-dimensional Strouhal Number (<i>St</i>) is investigated and results prove the dependency of <i>St</i> on the blockage coefficient and aspect ratio. It is shown that the Strouhal number will increase with the rise of blockage ratio and the local maximum of <i>St</i> will occur at lower <i>Re</i> for geometries with lower aspect ratios (bluff bodies) than geometries with higher aspect ratios, i.e. with more streamlined bodies.

NLSEmagic: Nonlinear Schrödinger equation multi-dimensional Matlab-based GPU-accelerated integrators using compact high-order schemes

We present a simple to use, yet powerful code package called NLSEmagic to numerically integrate the nonlinear Schrödinger equation in one, two, and three dimensions. NLSEmagic is a high-order finite-difference code package which utilizes graphic processing unit (GPU) parallel architectures. The codes running on the GPU are many times faster than their serial counterparts, and are much cheaper to run than on standard parallel clusters. The codes are developed with usability and portability in mind, and therefore are written to interface with MATLAB utilizing custom GPU-enabled C codes with the MEX-compiler interface. The packages are freely distributed, including user manuals and set-up files. Program summaryProgram title: NLSEmagicCatalogue identifier: AEOJ_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOJ_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 124453No. of bytes in distributed program, including test data, etc.: 4728604Distribution format: tar.gzProgramming language: C, CUDA, MATLAB.Computer: PC, MAC.Operating system: Windows, MacOS, Linux.Has the code been vectorized or parallelized?: Yes.Number of processors used: Single CPU, number of GPU processors dependent on chosen GPU card (max is currently 3072 cores on GeForce GTX 690).Supplementary material: Setup guide, Installation guide.RAM: Highly dependent on dimensionality and grid size. For typical medium–large problem size in three dimensions, 4GB is sufficient.Keywords: Nonlinear Schröodinger Equation, GPU, high-order finite difference, Bose-Einstien condensates.Classification: 4.3, 7.7.Nature of problem:Integrate solutions of the time-dependent one-, two-, and three-dimensional cubic nonlinear Schrödinger equation.Solution method:The integrators utilize a fully-explicit fourth-order Runge–Kutta scheme in time and both second- and fourth-order differencing in space. The integrators are written to run on NVIDIA GPUs and are interfaced with MATLAB including built-in visualization and analysis tools.Restrictions:The main restriction for the GPU integrators is the amount of RAM on the GPU as the code is currently only designed for running on a single GPU.Unusual features:Ability to visualize real-time simulations through the interaction of MATLAB and the compiled GPU integrators.Additional comments:Setup guide and Installation guide provided. Program has a dedicated web site at www.nlsemagic.com.Running time:A three-dimensional run with a grid dimension of 87×87×203 for 3360 time steps (100 non-dimensional time units) takes about one and a half minutes on a GeForce GTX 580 GPU card.

Determination of efficient offset of series regarding to each other during the formation of well spacing

The article describes the results of the determining of the most effective offset of wells in the row regarding the next row during the formation of well spacing. Rational grid dimensions of hole charges blasting, which consider the average radius of the crater grinding, coefficient of anisotropy and the angle between the direction of maximum destruction and slaughter line are offered

Quasi-optical terahertz polarizers enabled by inkjet printing of carbon nanocomposites

We report an approach for cost-effective manufacturing of THz quasi-optical polarizers by inkjet printing of polymer-carbon nanowhisker (CNW) dispersions. The electromagnetic interference properties of coatings with fixed CNW/polymer composition and varying thickness are quantified by a frequency domain THz spectroscopy system in the range 570–630 GHz. A shielding effectiveness of ∼40 dB is attained for 70 μm-thick coatings. A prototype THz polarizer printed on Mylar film displayed transmission and absorbance that varied with polarization orientation. The degree of polarization for film thickness of ∼1 μm was 0.35. This performance can be improved by refining grid dimensions, increasing coating thickness and adopting multi-layer polarizer structures.

Modeling hydraulic fractures in finite difference simulators using amalgam local grid refinement (LGR)

Hydraulic fracturing allows numerous, otherwise unproductive, low-permeability hydrocarbon formations to be produced. The interactions between the fractures and the heterogeneous reservoir rock, however, are quite complex, which makes it quite difficult to model production from hydraulically fractured systems. Various techniques have been applied in the simulation of hydraulically fractured wells using finite difference simulators; most of these techniques are limited by the grid dimensions and computing time and hardware restrictions. Most of the current analytical techniques assume a single rectangular shaped fracture in a single-phase homogeneous reservoir, the fracture is limited to the block size and the fracture properties are adjusted using permeability multiplier. The current work demonstrates how to model these systems with a smaller grid block size which allows you to apply sensitivity to the fracture length and model the fracture with enhanced accuracy. It also allows you to study the effect of reservoir heterogeneity on the fractured well performance. It is proposed to apply amalgam LGR technique to decrease the grid size to the dimensions of the hydraulic fracture without dramatically increasing the number of grid blocks which would cause a great increase in the computing time and the model size with no added value. This paper explains how the amalgam LGR is designed and compares between standard LGRs and the proposed design and a case study is presented from an anonymous field in Egypt to illustrate how to use this technique to model the hydraulically fractured well. The simulation model is matched to available production data by changing fracture lengths. Then the model is used to predict future response from the wells. The advantage of this technique is that it allows hydraulically fractured reservoirs to be modeled with less grid size which will lead to more realistic models and more accurate predictions; however, the most useful application of this technique may be in the fracture modeling stage. With this tool, various fracture geometries and scenarios can be tested in the simulator, and the most economic scenarios selected and implemented. This will lead to better fracture placement, and ultimately greater production.

SiCer - A substrate to combine ceramic and silicon based micro systems

A silicon-on-ceramic (SiCer) wafer-shaped substrate, allowing a simultaneous fabrication of ceramic and silicon based microsystems is presented. The substrate, based on the recently introduced 'silicon-on-ceramic integration concept', can be processed by standard MEMS and LTCC technologies. The monolithic compound is fabricated by using lamination and pressure assisted firing of a nano patterned silicon wafer with a low temperature cofired ceramic tape (LTCC). The LTCC is adapted to silicon (TCE and morphology). LTCC functionalities such as electrical and thermal vias, passives, fluidic channels, etc.,. can be pre-processed in grid dimensions or individually. Through Silicon Vias (TSV) in the silicon layer can be combined with the vias in the LTCC. The silicon layer can be fabricated as thin as necessary for the desired functionality, whereas the insulating LTCC layer ensures the mechanical stability of the SiCer wafer. In addition, the LTCC layer includes electrical functionalities like signal routing and passive integration. Using SiCer substrates, the bigger part of back-end processes for silicon microsystems such as assembly and the crucial part of packaging, can take place before any micro structuring is generated. Thus, the influence of these processes to the sensitive micro structures can be minimized. The SiCer substrate is fundamentally temperature-stable up to 1000 °C. The fabrication steps of the SiCer substrate, particularly several options for TSV's are explained. Material characteristics and new technological approaches with the SiCer substrate are presented.

Direct numerical simulation of turbulent flow over backward-facing at high Reynolds numbers

Direct numerical simulation (DNS) was performed for the first time to study the flow over a backward-facing step at a high Reynolds number on a coarse grid. The flow over backward-facing step is the typical turbulent flow controlled by large eddy, in which the effect of small eddy could be negligible as an approximation. The grid dimension could easily satisfy the resolution requirement to describe the characteristics of a large eddy flow. Therefore, direct numerical simulation of N-S equations to obtain the turbulent flow field on the coarse grid could be realized. Numerical simulation of a two-dimensional flow over a backward-facing step at a Reynolds number Re=44000 was conducted using Euler-Lagrange finite element scheme based on the efficient operator-splitting method (OSFEM). The flow field was descretized by triangle meshes with 16669 nodes. The overall computational time only took 150 min on a PC. Both the characteristics of time-averaged and instantaneous turbulent flow were simultaneously obtained. The analysis showed that the calculated results were in good agreement with the test data. Hence, the DNS approach could become the reality to solve the complex turbulent flow with high Reynolds numbers in practical engineering.

Exact solution of the 2-dimensional grid arrangement problem

Given an undirected graph G=(V,E), we consider injective mappings of its vertices to the k-dimensional Cartesian integer grid. Among such embeddings we are interested in those that minimize the sum of the resulting edge lengths, where the length of an edge is defined by the L1-metric. The case k=1 is the well-known Minimum Linear Arrangement Problem. We prove that the general problem is NP-hard for any fixed grid dimension. Our computational study focuses on the case k=2. We present as a first exact optimization algorithm a branch-and-cut scheme for sparse graphs. Several classes of valid inequalities are introduced and analyzed for facet defining properties of two corresponding polyhedra. Finally, computational results from a successful real-world application of the problem at the German Cancer Research Center (DKFZ) are presented.

Pseudo Relative Permeability Compensation for Numerical Dispersion

Reservoir simulation is an approach of recreating the occurring phenomena of the reservoir by solving the general governing equations that describe the reservoir processes. Finite difference technique is an effective method to get the solution out of the reservoir models for different scenarios. In light of many benefits of using course grid models rather than fine grid and simplification, using the same relative permeability curves from laboratory cannot be applied in the fields having large grid dimensions because of numerical dispersion (smearing) of finite difference modeling. Thus, the relative permeability curves must be modified based on the grid size and then applied into the simulator. The authors introduce a methodology to demonstrate how the lab relative permeability curves can be modified based on coarse grid sizes to honor the same anticipated rock behavior. Thus, an objective function is developed to minimize the numerical dispersion in a synthetic tilted reservoir by automatically changing the relative permeability and comparing the results with the equivalent fine model. By this method, modified relative permeability curves can be obtained and introduced to the coarse model. This modification workflow is almost inevitable for reservoir simulation models with very coarse grids and it eases the history-matching process by approaching more realistic solution.

Modelling a nanowire grid for light-sensing applications

Nanostructures hold promise as building blocks for a new generation of sensing devices because they could enhance detection and conversion of nonelectrical phenomena into electrical signals. In this paper, we discuss the possible use of a semiconductor (GaAs) nanowire grid as a light sensor. Based on the previously measured electrical properties of a single GaAs nanowire, we propose a model to determine the resistance of a structure consisting of many nanowires forming a grid with metallic contacts. Due to the fact that the proposed geometry is partially disordered, the total resistance of the structure is determined implementing the random resistor network (RRN) methodology in our simulation model. In order to reduce the error caused by condition number and the machine epsilon, the RRN model is improved by introducing additional conditions for solving the transfer matrix formulation precisely. The proposed complex nanowire geometry is analysed for different grid sizes varying the number of nanowires and contacts. According to the nanowire doping profile, we have defined the fraction of active segments (FoS) that is light-sensitive. Simulation results have shown that light sensitivity of a nanowire grid is enhanced with increasing number of active segments while a relative change in the active segment resistance has only a minor influence on the resistance of the complete structure. Finally, we have optimized nanowire grid dimensions with respect to the simulation results and practical limitations.

Supramolecular architectures based on various macrocyclic metallic tectons with 1,3,5-triazine-2,4,6-triamine hexaacetic acid ligand

Reactions of series of macrocycle derivatives [Ni(hto)]Cl2·2H2O (1) (hto = 1,3,6,9,11,14-hexaazatri-cyclo[12.2.1.16,9]octadecane), [Ni(CHA)](ClO4)2 (2) (CHA = 1,3,6,8,11,14-hexaazatri-cyclo[12.2.1.18,11]octadecane), [Ni(PCHA)](ClO4)2 (3) and [Cu(PCHA)](ClO4)2 (4) (PCHA = 4-methyl-1,3,6,8,11,14-hexaazatri-cyclo[12.2.1.18,11]octadecane), with a flexible hexapodal ligand H6TTHA (H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid) resulted in eight supramolecular coordination polymers (SCPs), formulated as α-[Ni(hto)][H4TTHA]·5H2O (5), β-[Ni(hto)][H4TTHA]·4H2O (6), [Ni(CHA)][H4TTHA]·2H2O (7), [Ni(PCHA)][H4TTHA]·3H2O (8), [Cu(PCHA)][H4TTHA]·1.5H2O (9), [Ni(PCHA)][H5TTHA](ClO4)·4H2O (10), [Ni(PCHA)][H4TTHA]·DMSO·H2O (11) and [Ni(PCHA)][H4TTHA]·DMF (12). These compounds are structurally characterized by X-ray diffraction analyses. The predominant driving forces that connect macrocyclic metallic tectons with hexaacetic acid ligand in compounds 5–12 are hydrogen bonds, by which the compounds assemble into SCPs with versatile structures. The single-crystal X-ray diffraction analysis reveals that compounds 5 and 6 contain a rhombic 2-D layer network structure constructed of hydrogen bonds. Compound 7 exhibits a 3-D supramolecular network with 12 × 10.4 A2 1-D brick wall net structure along the c-axis, and all the water molecular guests adorned the brick wall net. Compounds 8 and 9 show a nonporous 3-D framework also stabilized by the hydrogen bonds. Tuning by solvents, in compound 10, an elliptical 2-D network was found to accommodate water molecules and perchlorate in the channels, with grid dimensions of 11 × 10 A2; compounds 11 and 12 show 2-D honeycomb-like networks with diameter 12 A. In conclusion, the crystal structures and regulatory effect of thev N-donor on the macrocyclic ligands in these compounds are discussed.

Large and small baseload power plants: Drivers to define the optimal portfolios

Despite the growing interest in Small Medium sized Power Plants (SMPP) international literature provides only studies related to portfolios of large plants in infinite markets/grids with no particular attention given to base load SMPP. This paper aims to fill this gap, investigating the attractiveness of SMPP portfolios respect to large power plant portfolios. The analysis includes nuclear, coal and combined cycle gas turbines (CCGT) of different plant sizes. The Mean Variance Portfolio theory (MVP) is used to define the best portfolio according to Internal Rate of Return (IRR) and Levelised Unit Electricity Cost (LUEC) considering the life cycle costs of each power plant, Carbon Tax, Electricity Price and grid dimension. The results show how large plants are the best option for large grids, while SMPP are as competitive as large plants in small grids. In fact, in order to achieve the highest profitability with the lowest risk it is necessary to build several types of different plants and, in case of small grids, this is possible only with SMPP. A further result is the application of the framework to European OECD countries and the United States assessing their portfolios.

Quantifying Changes in Fibrin Fiber Network Morphology

During blood clotting, thrombin and fibrinogen interact, whereby thrombin cleaves the fibrinogen molecule into two peptides, the fibrinopeptides, ultimately forming fibrin monomers. These fibrinogen monomers assemble to form a fibrin network that may be studied using ultrastructural techniques. This study investigates the use of a grid, placed onto a micrograph, to quantify changes in morphology. The fibrin fiber micrographs of a healthy donor were compared to a database of donors and were shown to be a true representative of a typical healthy individual. Eighteen micrographs of this single donor were taken at 40,000× machine magnification, and a grid was placed over the micrographs. The grid dimensions were calculated by using the scale bar inserted onto the micrograph. Each grid block was equal to 0.5 by 0.5 µm for a total grid area of 28 µm2. A percentage changed fibrin fiber morphology was then calculated for each 28 µm2 of fibrin clot produced in the laboratory. It is concluded that this effortless and simple grid technique to quantify changes in ultrastructure of fibrin clot morphology may provide a method to statistically quantify changes in fibrin fiber ultrastructure when studying conditions affecting hemostasis.

Development of a linear predictive model for carbon dioxide sequestration in deep saline carbonate aquifers

CO 2 injection into deep saline aquifers is a preferred method for mitigating CO 2 emission. Although deep saline aquifers are found in many sedimentary basins and provide very large storage capacities, several numerical simulations are needed before injection to determine the storage capacity of an aquifer. Since numerical simulations are expensive and time-consuming, using a predictive model enables quick estimation of CO 2 storage capacity of a deep saline aquifer. In order to create a predictive model, the ranges of variables that affect the CO 2 storage capacity were determined from published literature data. Correlations found in literature were used for other important parameters such as pore volume compressibility and density of brine. Latin hypercube space filling design was used to construct 100 simulation cases prepared using CMG STARS. The simulation period covered a total of 300 years of CO 2 storage. By using a least-squares method, linear and nonlinear predictive models were developed to estimate CO 2 storage capacity of deep saline carbonate aquifers. Numerical dispersion effects were considered by decreasing the grid dimensions. It was observed that a dimensionless linear predictive model is better than the nonlinear. The sensitivity analyses showed that the most important parameter that affects CO 2 storage capacity is depth. Most of the (up to 90%) injected gas dissolved into the formation water and a negligible amount of CO 2 reacted with carbonate.

Proper cell dimension and number of particles per cell for DSMC

The Direct Simulation Monte Carlo (DSMC) method models fluid flows using simulation particles which represent a large number of real molecules in a probabilistic simulation to solve the Boltzmann equation. Different opinions still exist on some basic understandings of the controlling factors of DSMC method, such as the proper grid dimension and the proper number of particles in a cell. In this contribution, DSMC simulation of Poiseuille flow was carried out to evaluate the dependence of simulation results on cell dimension and number of particles per cell. In the simulation process a self-adaptive block-structured grid system was employed to guarantee that the number of particles per cell is constant. The simulation covers both 2D and 3D, slip flow regime and transition flow regime, and for each regime, covers both high pressure and low pressure cases. Our simulation results indicate that the number of particles per cell and scaling factor have little influence on simulation result for both slip flow and transition flow when the number of particles per cell is greater than 5, but the dimension of cell influences the accuracy of results significantly. The error caused by cell dimension decreases with the decrease of cell dimension. It is concluded that in the DSMC method it is necessary to ensure that the cell is less than 1/2 of molecular mean free path.

Sensitivity to Basis Mismatch in Compressed Sensing

The theory of compressed sensing suggests that successful inversion of an image of the physical world (broadly defined to include speech signals, radar/sonar returns, vibration records, sensor array snapshot vectors, 2-D images, and so on) for its source modes and amplitudes can be achieved at measurement dimensions far lower than what might be expected from the classical theories of spectrum or modal analysis, provided that the image is sparse in an apriori known basis. For imaging problems in spectrum analysis, and passive and active radar/sonar, this basis is usually taken to be a DFT basis. However, in reality no physical field is sparse in the DFT basis or in any apriori known basis. No matter how finely we grid the parameter space the sources may not lie in the center of the grid cells and consequently there is mismatch between the assumed and the actual bases for sparsity. In this paper, we study the sensitivity of compressed sensing to mismatch between the assumed and the actual sparsity bases. We start by analyzing the effect of basis mismatch on the best k-term approximation error, which is central to providing exact sparse recovery guarantees. We establish achievable bounds for the l1 error of the best k -term approximation and show that these bounds grow linearly with the image (or grid) dimension and the mismatch level between the assumed and actual bases for sparsity. We then derive bounds, with similar growth behavior, for the basis pursuit l1 recovery error, indicating that the sparse recovery may suffer large errors in the presence of basis mismatch. Although, we present our results in the context of basis pursuit, our analysis applies to any sparse recovery principle that relies on the accuracy of best k-term approximations for its performance guarantees. We particularly highlight the problematic nature of basis mismatch in Fourier imaging, where spillage from off-grid DFT components turns a sparse representation into an incompressible one. We substantiate our mathematical analysis by numerical examples that demonstrate a considerable performance degradation for image inversion from compressed sensing measurements in the presence of basis mismatch, for problem sizes common to radar and sonar.

Understanding the impacts of quality assessment: an exploratory use of cultural theory

Cultural theory is tentatively used to understand how far quality assessment affects institutions by influencing the group and grid dimensions. This paper argues that the self‐assessment phase of the Portuguese system, in use until recently, promoted the egalitarian (logic of mistrusting power and expertise) and the individualist (logic of freedom and autonomy) ways of life as its structure was based on academic cooperation and closed to society. However, the external assessment phase emphasised the individualist and hierarchical ways of life, the latter promoting the logic of authority and expertise. This analysis presents the dynamics of quality assessment as a step‐by‐step process rather than a broad‐spectrum development. This attempt to apply the grid/group cultural theory to the opinions expressed on the establishment of quality assessment systems of Portuguese universities is promising. Moreover, if it is accepted that pressures from outside will enforce the grid dimension, to avoid the fatalist way of life the group dimension should be reinforced, by adopting policies and strategies to increase the group membership. These policies might be linked either to social capital or to collegiality.

Optimal design of electrode grids dimensions for ITO‐free organic photovoltaic devices

AbstractThe aim of this work is to present an optimized model of metallic micro‐grid used as anode electrode in organic photovoltaic devices excluding the use of expensive ITO (Indium Tin Oxide). A design of circular grid, adapted for silcon‐based solar cells, is proposed here. A clear advantage of using the grid as opposed to ITO is the elimination of the absorptive losses the ITO adds to the structure. In order to optimize the collecting grid dimensions one must choose a compromise between the resistive losses, represented by the series resistance Rs, and the shadowing loss. Therefore, in order to find the best geometry of the grid, a comparative study has been done between the linear geometry and the circular one. Our results show clearly that the efficiency is enhanced when using the circular geometry. Copyright © 2010 John Wiley &amp; Sons, Ltd.