Grid Dimensions Research Articles

Selecting subgrids from a spatial monitoring network: Proposal and application in semiconductor manufactoring process

AbstractThe monitoring of spatial production processes typically involves sampling network to gather information about the status of the process. Sampling costs are often not marginal, and once the process has been accurately calibrated, it might be appropriate to reduce the dimension of the sampling grid. This aim is often achieved through the allocation of a brand new network of less dimension. In some cases that is not possible and it might be necessary the selection of a subgrid extracted from the original network. Motivated by a real semiconductor problem, we propose a method to extract a monitoring subgrid from a given one, based upon grid representativeness, accuracy, and spatial coverage of the subgrid and, if available, by expert knowledge of the weights to be assigned to those areas where production may need greater precision. Discussion is mainly focused on circular spatial domain, since, in microelectronics, the basic production support, called wafer, is a circle. Straightforward generalizations to different spatial domains are possible. Furthermore, conditionally upon the availability of experimental data, we check the loss of accuracy by fitting a dual mean‐variance response surface on the reduced grid. Joining the latter information and the criteria used to select the subgrid, we provide additional guidelines on how to fine‐tune the subgrid selection. Real case studies are used to show the effectiveness of the proposal.

Cultural attributes and risk perception: the moderating role of different types of research and development

Drawing on the grid–group culture theory, this study examines hypotheses to explain how the cultural attributes of an organization influence professionals’ perceptions of risk in the context of research and development (R&D) activities. Specifically, we explore whether two dimensions of cultural attributes – the grid dimension and the group dimension – affect organizational commitment and risk perception. We also investigate whether the impact of the cultural attributes on risk perception is mediated by organizational commitment and whether different types of R&D activities – applied research and developmental research – serve as a moderating variable on the relationships among cultural attributes, organizational commitment, and risk perception. The partial least squares method was used to analyze data collected from full-time senior researchers with over five years of experience at a large technology institute. Our findings indicate that cultural attributes influence the risk perception of R&D professionals through the mediating function of organizational commitment. Further, we found that different types of R&D activities have moderating effects on the relationship between organizational commitment and risk perception.

A filter attribute selection method based on local reliable information

In this article, a filter feature weighting technique for attribute selection in classification problems is proposed (LIA). It has two main characteristics. First, unlike feature weighting methods, it is able to consider attribute interactions in the weighting process, rather than only evaluating single features. Attribute subsets are evaluated by projecting instances into a grid defined by attributes in the subset. Then, the joint relevance of the subset is computed by measuring the information present in the cells of the grid. The final weight for each attribute is computed by taking into account its performance in each of the grids it participates. Second, many real problems contain low signal-to-noise ratios, due to instance of high noise levels, class overlap, class imbalance, or small training samples. LIA computes reliable local information for each of the cells by estimating the number of target class instances not due to chance, given a confidence value. In order to study its properties, LIA has been evaluated with a collection of 18 real datasets and compared to two feature weighting methods (Chi-Squared and ReliefF) and a subset feature selection algorithm (CFS). Results show that the method is significantly better in many cases, and never significantly worse. LIA has also been tested with different grid dimensions (1, 2, and 3). The method works best when evaluating attribute subsets larger than 1, hence showing the usefulness of considering attribute interactions.

An Improved Compressive Sensing and Received Signal Strength-Based Target Localization Algorithm with Unknown Target Population for Wireless Local Area Networks.

In this paper a two-phase compressive sensing (CS) and received signal strength (RSS)-based target localization approach is proposed to improve position accuracy by dealing with the unknown target population and the effect of grid dimensions on position error. In the coarse localization phase, by formulating target localization as a sparse signal recovery problem, grids with recovery vector components greater than a threshold are chosen as the candidate target grids. In the fine localization phase, by partitioning each candidate grid, the target position in a grid is iteratively refined by using the minimum residual error rule and the least-squares technique. When all the candidate target grids are iteratively partitioned and the measurement matrix is updated, the recovery vector is re-estimated. Threshold-based detection is employed again to determine the target grids and hence the target population. As a consequence, both the target population and the position estimation accuracy can be significantly improved. Simulation results demonstrate that the proposed approach achieves the best accuracy among all the algorithms compared.

Improved spectral clustering for multi-objective controlled islanding of power grid

We propose a two-step algorithm for optimal controlled islanding that partitions a power grid into islands of limited volume while optimizing several criteria: maximizing generator coherency inside islands, minimizing power flow disruption due to teared lines, and minimizing load shedding. Several spectral clusterings strategies are used in the first step to lower the problem dimension (taking into account coherency and disruption only), and CPLEX tools for the mixed-integer quadratic problem are employed in the second step to choose a balanced partition of the aggregated grid that minimizes a combination of coherency, disruption and load shedding. A greedy heuristics efficiently limits search space by generating the starting solution for the exact algorithm. Dimension of the second-step problem depends only on the desired number of islands K instead of the dimension of the original grid. The algorithm is tested on the standard systems with 118, 2383, and 9241 nodes showing high quality of partitions and competitive computation time.

Rotational influences on aerodynamic and heat transfer behavior of gas turbine blade vortex cooling with bleed holes

The suitable vortex chamber model with bleed holes is established to further investigate vortex cooling mechanism. Numerical simulations are performed by solving 3D steady Reynolds Averaged Navier-Stokes (RANS) equations and the k-ω turbulence model. Grid independence analysis is conducted to obtain the proper grid dimension. Effects of rotation number (Ro=0, 0.227, 0.464, 0.718, 1), rotating direction (Ro=−0.464, 0.464), density ratio (Δρ/ρ=0.2, 0.3, 0.4, 0.5) on flow and heat transfer behavior of vortex cooling with bleed holes are researched in detail. The rotation number is defined as Ro=ωDh/U, where ω, Dh and U represent the rotational angular velocity, chamber cross section hydraulic diameter and mean axial velocity. Results indicate that the existence of bleed holes can disturb vortex flow and enhance heat transfer intensity. Model rotation has obvious influences on flow and thermal performance of vortex cooling with bleed holes. As the rotation number increases from 0 to 1, the air rotational flow velocity and static pressure decrease, thus leading to decreasing heat transfer intensity by 19.2%. Compared with Ro=−0.464, higher rotational velocity flow and lower inlet static pressure exist at Ro=0.464, hence the heat transfer intensity is higher and shows more uniform. The cooling air rotational flow in the vortex chamber is almost independent of density ratio. The vortex heat transfer intensity will increase by 29.6% with the increasing density ratio from 0.2 to 0.5.

The traveling salesman problem on grids with forbidden neighborhoods

We introduce the traveling salesman problem with forbidden neighborhoods (TSPFN). This is an extension of the Euclidean TSP in the plane where direct connections between points that are too close are forbidden. The TSPFN is motivated by an application in laser beam melting. In the production of a workpiece in several layers using this method one hopes to reduce the internal stresses of the workpiece by excluding the heating of positions that are too close. The points in this application are often arranged in some regular (grid) structure. In this paper we study optimal solutions of TSPFN instances where the points in the Euclidean plane are the points of a regular grid. Indeed, we explicitly determine the optimal values for the TSPFN and its associated path version on rectangular regular grids for different minimal distances of the points visited consecutively. For establishing lower bounds on the optimal values we use combinatorial counting arguments depending on the parities of the grid dimensions. Furthermore we provide construction schemes for optimal TSPFN tours for the considered cases.

Hillslope-scale prediction of terrain and forest canopy effects on temperature and near-surface soil moisture deficit

Soil moisture has important effects on fuel availability, but is often assessed using drought indices at coarse spatial resolution, without accounting for the fine-scale spatial effects of terrain and canopy variation on forest floor moisture. In this study, we examined the spatial variability of air temperature, litter temperature and near-surface soil moisture (θ, 0–100 mm) using data from field experiments at 17 sites in south-east Australia, covering a range of topographic aspects and vegetation types, within climates from semiarid to wet montane. Temperatures and θ in mountainous environments were found to vary at much finer spatial scales than typical drought index grid dimensions (several kilometres). Using terrain elevation, local insolation ratio and plant area index, we developed semi-empirical microclimate models for air and litter temperatures, then used modelled temperatures as input into calculations of the Keetch–Byram Drought Index, a widely used index of soil moisture deficit. Drought index results based on predicted litter temperature were found to explain 91% of the spatial variation in near-surface soil moisture at our experimental sites. These results suggest the potential for routine hillslope-scale predictions of forest floor moisture status, which may be useful in the management of fire, particularly prescribed burning, in complex terrain.

Towards an expeditious as-is surface reconstruction

Conservation and rehabilitation of structures such as urban buildings and heritage requires a growing effort on the establishment of sufficiently comprehensive documentation concerning the time evolution of these structures’ characteristics and health condition. These documentation archives and databases should be much more than just a collection of structure’s design plans, and desirably they should contain information about the as-built and as-is states of a certain structure. Due to the technological evolution of data acquisition systems, 3D laser scanning points’ clouds became an important data source that enables the subsequent representation of 3D surface’s geometries, and thus the constitution of data repositories. However, it is known that the volume of data obtained, can be enormous and the computation time to process it, a heavy task. The present work proposes an expeditious, continuous processing methodology that aims in a first step the generation of a points’ structured grid and its associated triangle structured mesh by defining an injective function from a virtual surface onto the surface’s cloud points. The additional possibility of selecting the virtual grid dimension to be used, enable representations with different levels of detail. In a second step, the resulting structured grids are used to reconstruct the corresponding surfaces by considering compactly-supported radial basis functions. The main contribution of this work is thus related to the proposal of an expeditious integrated processing methodology of points’ clouds. A set of case studies are presented to illustrate the performance of the present integrated methodology.

Control the cost, touch and step voltages of the grounding grids design

In this study, an evolutionary strategy is presented to get the optimal grounding grid design to minimise the design cost, the touch and step voltages of the grounding grid to ensure the economical constraint as well as the safety conditions. The proposed technique is used for one and two-layer soil. This technique is based on the comparison between the quality factors of the initial grid dimension according to the cost, touch and step voltages with the other quality factors obtained from new generations (offspring) of the grid dimensions. Effects of top layer thickness, number of grid meshes, vertical rods number and length, and the soil resistivity of the top and bottom layers on grounding resistance (R g) and earth surface potential are studied. Different case studies are introduced to evaluate the performance of the proposed technique and to provide the knowledge about the grid dimensions that is substantial for the economical design of the grounding grids.

The geopolitics of cross-border electricity grids: The Israeli-Arab case

Countries often attempt to establish regional electricity grids. However, whereas research on natural resources frequently seeks to understand policy outcome through a geopolitical prism, when it comes to electricity studies the prism is always economic or technical. Hence, this study is a first attempt to identify the geopolitical dimension of cross-border electricity grids. The study argues that success in establishing electricity grids requires identifying how the geopolitical dimension interplays with the physical dimension. To examine the role of these geopolitical bottlenecks, the study examines negotiation protocols, spanning over 15 years, on establishing ten grid connections between Israel and its Arab neighbors. It finds that electricity geopolitics has been used both as a platform for deeper international cooperation and as a stick against neighboring states. When policies are driven by a peace dividend, proposals for grid connection appear to evolve and overcome the dependency and the security-economy bottlenecks. When relations deteriorate, proposals for grid connections appear to undergo reconsideration and to be held hostage by higher politics. If, when and how electricity grids materialize is a function of the nature of the electricity network as a twofold package and of the ability of the planning process to accommodate geopolitical uncertainty.

Improved Performance in Flexible Organic Solarcells Via Optimization of Highly Transparent Silvergrid/Graphene Electrodes

Organic solar cells (OSCs) were fabricated on polyethylene terephthalate (PET) substrates using hybrid silver grid/graphene films as transparent conducting electrodes and the effect of the silver grid dimensions was characterized. OSCs fabricated using optimized grid dimensions of 200 mm X 200 mm X 50 nm X 2 mm (length X width X height X linewidth) on PET substrates exhibited two times the power conversion efficiency of control devices using graphene only.

An efficient parallel implementation of cell mapping methods for MDOF systems

The long-term behavior of dynamical system is usually analyzed by means of basins of attraction (BOA) and most often, in particular, with cell mapping methods that ensure a straightforward technique of approximation. Unfortunately, the construction of BOA requires large resources, especially for higher-dimensional systems, both in terms of computational time and memory space. In this paper, the implementation of cell mapping methods toward a distributed computing is undertaken; a new efficient parallel algorithm for the computation of large-scale BOA is presented herein, also by addressing issues arising from the inner seriality related to the BOA construction. A cell mapping core is thus wrapped in a management shell, and in charge of the core administration, it permits to split over a multicore environment the computing domain, by carrying out an efficient use of the distributed memory. The proposed approach makes use of a double-step algorithm in order to generate, first, the multidimensional BOA of the system and then to evaluate arbitrary 2D Poincare sections of the hypercube that stores the information. An analysis on a test system is performed by considering different dimensional grids; the effort of a parallel implementation toward medium and large clusters is balanced by a great results in terms of computational speed. The performances are strictly affected not only by the number of cores used to run the code, but in particular in the way they are instructed. To get the best from an implementation on a massive parallel architecture, the processes must be properly balanced between memory operations and numerical integrations. A significant improvement in the elaboration time for a large computing domain is shown, and a comparison with a serial code demonstrates the great potential of the application; the advantages given by the use of parallel reading/writing are also discussed with respect to the BOA grid dimension.

An improved method to estimate the fractal dimension of colour images

Summary Fractal dimension (FD) is an important feature of fractal geometry has many applications in various fields including image processing, image analysis, texture segmentation, shape classification and identifying the image features such as roughness and smoothness of an image. There are many techniques to estimate the dimension of fractal surface. The famous technique to calculate fractal dimension is the grid dimension method, which is popularly known as box counting method and some of the other improved methods like differential box counting and improved differential box counting method are used to estimate fractal dimension of grayscale images. The usual way of estimating the roughness or FD of color image involves two steps: (i) converting color image to grayscale and (ii) finding the roughness of generated grayscale image. But due to this conversion, significant color information is lost and leads to inaccurate roughness estimation. To avoid such inaccuracy this paper proposes the development and study of novel technique for estimating fractal dimension of color images. In this study, the improved differential box counting method is applied to the 24 bit representation of RGB color images to extract the roughness of color images. The validation of the proposal is performed by generating twelve different synthesized color images in terms of small variation of intensity value in RGB space and compared with previously three well defined existing methods that are weighted sum, average and desaturation method. The results showed that our proposed method is able to capture the accurate sharp variation of roughness as compared to the existing methods.

Effects of aerodynamic parameters on steam vortex cooling behavior for gas turbine blade leading edge

Three-dimensional Reynolds-averaged Navier–Stokes equations are applied to further explore steam vortex cooling mechanism in gas turbine blade leading edge. Grid independence analysis and turbulence model validation are carried out to determine the proper grid dimension and turbulence model for simulations. Influences of Reynolds number and temperature ratio on steam vortex cooling flow and heat transfer behavior for the blade leading edge are investigated. Heat transfer and friction correlations for steam vortex cooling are achieved on the basis of numerical data. Results show that radial convection is generated due to violent rotational motion and uneven density distribution, contributing to heat transfer enhancement. For the sake of increasing steam velocity, the obvious increase in heat transfer intensity and decrease in friction coefficient are observed with the increasing Reynolds number. When the temperature ratio increases, the heat transfer intensity decreases slightly and the friction coefficient decreases significantly. The thermal performance increases with the increasing Reynolds number and the decreasing temperature ratio. Compared with calculating results, the heat transfer and friction correlations can predict steam vortex cooling characteristics accurately.

The Correlation Dimension of a Rectilinear Grid

The correlation dimension dC of a finite network measures how the fraction of nodes at a given distance from a random node scales with the distance. However, there is no standardized formal definition of dC for a network. We consider various possible definitions of dC for a finite unweighted and undirected rectilinear grid in one, two, and three dimensions. We propose a simple “overall slope” definition for dC which yields an exact closed form expression for such grids. We prove that the overall slope definition satisfies two properties that should be satisfied by any definition of the correlation dimension of a network. Lastly, we present a conjecture giving a closed form expression for the overall slope correlation dimension of a finite rectilinear grid in E dimensions, for any positive integer E.

Determination Formability of Tubular (AL-alloy) by Hydraulic Bulge Test

This study aims to establish the forming limit diagrams of tubular material by bulge test.The bulge test applies internal (hydraulic) pressurewith and without applied axial feeding on tubularspecimen causing tube expansion, undergoing plastic deformation until bursting occurs. In order to investigate bulge test, a hydraulic bulgetool has been designed and manufactured with insert dies having profile die radius (10)mm. the fixed bulgeand the bulge with axial feeding can be fulfilled by this tool.Axial feeds applied to tube ends were (1, 3, 5, 7) mm. The process has been carried out using aluminum alloy (6063) tubes with dimension of (d_°=50 ,t_° =1.7,L_° =150) mm before and after annealing. Before doing the bulge test, tubes were annealed at temperatures of (425) ᵒC with holding time of two hours and then cooled in the furnace. Square grids have been printed on all tubes wall with dimension (5x5)mm. The grid was printed by screening method to calculation major and minor strain. A commercially available finite element program code (ANSYS11.0), was used to perform the numerical simulation of the bulge test. Maximum bulge height without axial feeding that can be obtained from tubes annealed at 425ᵒC was (4.62)mm with bursting pressure of (7.5)Mpa and final tube thickness of (1.42)mm.When applying axial feeding the max bulge height is(4.95)mm with bursting pressure of(9.5)Mpa and final tube thickness of (1.55)mm these results obtained from axial feeding(5)mm,wrinkling occurs when applying axial feeding(7)mm. Straincalculation wasperformed using software program (Matlab). The strain value was obtained by measured grid dimension before the bulge test and grid dimension after bulge test fortubes at all annealed temperatures and applied axial feeding. It is noted thatgood agreement between experimental and numerical results, the maximum error is 5.2%.

Surface plasmon resonance coupling effect of micro-patterned gold film

Surface-enhanced Raman scattering has a high sensitivity in the detections of complex biological systems, and it has a lot of potential applications in food inspection, biological imaging and biosensors in biochemistry, etc. Here, we investigate the surface Raman enhancements on gold films of different morphologies and further simulate the enhancements by using the finite difference time domain. To prepare the substrates with different morphologies, polymethyl methacrylate (PMMA) is spin coated 2000 rpm in one minute on a silicon wafer, followed by annealing at 180℃ for 5 min. Then, PMMA is etched by a 20 kV electron beam lithography. With the PMMA used as a soft imprint template, polydimethylsiloxane (PDMS) is dropped on the template then removed gently from the template after drying at 60℃ for 4 h. Finally, a gold thin film is prepared on the PDMS by magnetron sputtering with a current of 10 mA for 15 min. We design two kinds of morphologies:a four-way grid and a square morphology. The dimension of the four-way grids is 40 m and the grid width is 4 upm. The dimension of the square is also 4 upm. The cystine and melamine solutions with concentrations of 50, 100, 200 and 400 ppm are deposited on the surfaces of the gold thin film, respectively. The Raman spectra of cystine and melamine solutions are measured on the substrates with four-way grids and dot arrays. The Raman spectra of cystine on two kinds of substrates show no obvious difference. Due to the relatively small enhancement of melamine, the Raman peaks of melamine solutions of concentrations 50 and 100 ppm on the substrate of square morphologies are not easy to detect. On the contrary, all of the Raman spectra of melamine on the substrate of four-way grid morphologies are clear. The result indicates that the substrate with four-way grids has better sensitivity and enhancement performance. To verify the influence of the morphologies of the substrates on surface Raman enhancement and understand the mechanism of the enhancement, we simulate the scattering spectra and field distributions of different morphologies on gold thin films by using the finite difference time domain method. It is indicated that more complex the structure, the more obvious the enhanced Raman spectra will be. The calculations show that the enhancements of four-way grid morphologies are better than those of square morphologies. The predicted results of the surface enhanced Raman scattering are consistent with the measurements. These results will provide guidance and theoretical basis for further applications of surface enhanced.

Static Equivalent of Distribution Grids With High Penetration of PV Systems

High penetrations of photovoltaic (PV) systems within load pockets in distribution grids have changed pure consumers to prosumers. This can cause technical challenges in distribution and transmission grids, such as overvoltage and reverse power flow. Embedding voltage support schemes into PVs, such as standard ${\cos \phi (P)}$ characteristic proposed by the German grid codes, may cause more changes in the steady-state behavior of distribution grids and, in turn, the transmission side. Accordingly, it is important to properly model active distribution grids to analyze the system impacts of these changes to plan and operate future smart power grids. However, due to the high dimension of distribution grids, considering a detailed distribution grid to study the transmission side or a fraction of the distribution grid is either cumbersome or impractical. Therefore, it is required to develop a reasonable equivalent that can fairly capture the dominant behavior of the distribution grids. The aim of this paper is to use gray-box modeling concepts to develop a static equivalent of distribution grids comprising a large number of PV systems embedded with voltage support schemes. In the proposed model, the PV systems are aggregated as a separate entity, and not as a negative load, which is traditionally done. The results demonstrate the superior quality of the proposed model compared with the model with PV systems as the negative load.

One problem on generating 2D regular grids based on mappings

To study the known problem on generating a regular grid by means of the Winslow method in a rectangular domain with a boundary kink known as a backstep, a high-accuracy numerical method for the inverse harmonic mapping of the unit square onto the domain with a certain mapping of the domain boundaries is developed. The behavior of mapping level lines that enter the point of the boundary kink is studied. Near the kink, the angle between the boundary and the straight line connecting a point on the level line with a point of the boundary kink is found as a function of the coordinate of the point on the level line in the unit square. It is shown that the level line of the mapping is tangent to the boundary at the kink point. Near the kink point the mapping is not quasi-isometric. The regular grid generated according to the intersection points between the level lines connected by straight lines contains a self-intersecting cell that remains when the grid step along the boundary decreases. Based on the universal elliptical equations reproducing any nondegenerate mapping of the parametric rectangle onto a given domain, a simple two-parametric control of the grid nodes in the backstep that makes it possible to effectively control the slope angle of the grid line entering the point of the kink, thereby removing the escape of the grid lines from the domain boundary, is suggested. In the case of a small number of grid points 31 × 31, the nondegenerate grid is generated by selecting a suitable value of one parameter. If the number of grid nodes is increased by a factor of 8 along both directions (grid size 241 × 241), the nonconvex cells appear within the domain, which are easily removed by using the variational barrier method. Another possibility to avoid nonconvex cells is to decrease the grid dimension along the second direction (grid size 241 × 121).