Look up Table

CuRREnt niGht opERAtions are enabled through imaging in the visible–near-infrared band, as provided by Gen III image intensi-fier tubes in night-vision goggles, and in the thermal infrared (IR) bands, supported by a variety of for-ward-looking infrared (FLIR) imaging devices ...

Methane jet flame simulations have been performed in order to evaluate conserved scalar chemistry (CSC) approach in modelling combustion process inside cylindrical burner. Two combustion regimes were included: non-premixed and premixed. For both of them it was necessary to generate look-up tables in pre-processing stage. For non- premixed regime two combustion controlling parameter approaches were used: scalar dissipation rate and normalized reaction progress variable (nRPV) approach. For premixed regime only nRPV approach was used. As an addition to CSC module, discrete transfer radiation module (DTRM) radiation model was also included. Simulation results were compared with experimental data.

Augmented Reality (AR) is a method of combining computer-generated virtual content with the real world. This augmentation is often achieved with the aid of a head-mounted device that the user looks through. Computer-Generated Holography (CGH) is a way of shaping light waves to form / replay three-dimensional content. Unlike currently widespread stereoscopic 3D displays, holography is capable of reconstructing objects showcasing real depth information, leading to a superior viewing experience. This work explores various aspects of CGH within the context of optical seethrough near-eye displays suited for AR applications. Although Holographic AR displays only appeared in the 2010s, they have benefited from decades of research into Computer-Generated Holography for projection and display applications. The particular focus of this work is the hardware of Holographic AR devices. Listed and examined are all the physical and optical components of an AR system, namely: the light source and its coherence requirement, light source conditioning, spatial light modulator (SLM), SLM illumination, relay / magnification optics, and combiner optics. In each section, trade-offs which are necessary to navigate while building holographic AR systems are identified and analyzed. Suggestions on how to optimize the overall projector layout are offered throughout the text.

Lossless pixel value encrypted images still maintains the some properties of their respective original plain images. Ciphered Images that maintain the properties of their plain images of a given domain are very useful in certain applications where the conservation of pixel values but visual concealment is of a paramount concern. Medical images that have a fully reversible and recoverable process are of key importance in Medicine. Hence visually ciphered images stored or transmitted over secured or unsecured networks can also be analyzed in a forensic investigation to determine possible plain image equivalence. Digital Forensics processes have played crucial role in fighting crime both in society and cyberspace. In this paper, feature based cryptanalytic technique for digital forensics analysis of visual cryptographic digital image data based on formal concept analysis was proposed. Different techniques of visual cryptographic approaches were engaged in ciphering the plain image and our proposed approach was engaged in the cryptanalysis of the plain image after feature extractions from both the plain and the ciphered images. A lattice was generated which was then used authenticate and match the ciphered images to their respective ciphered plain images. At the end, the Galois lattice of both ciphered and plain image remained the same.

We demonstrate an efficient method of rendering alias-free synthetic images using precomputed convolution integrals. The method is based on the observation that a visible polygon fragment's contribution to an image is solely a function of its position and shape, and that within a reasonable level of accuracy, a limited number of shapes represent the majority of cases encountered in images commonly rendered. The convolution integral is precomputed for all pixels affected by the polygon fragment and is stored in a table. Completely visible fragments which are either triangular or trapezoidal produce two indices into the table. Most other fragments which are represented as differences of simple fragments. The remaining eases are characterized by a bit-mask for which each bit has a corresponding set of look up tables. The basic technique has been applied to several fundamentally different rendering algorithms. In addition, we illustrate a version of the newly introduced nonuniform sampling technique implemented in the same program, but with different table values.

In this paper, a Direct Torque Control method for Matrix Converters fed Induction Motors is proposed. A predictive algorithm which ensures minimum torque ripple is employed for the selection of the appropriate voltage vector from the Matrix Converter. A new look-up table for Direct Torque Control using Matrix Converters has been developed which delivers a set of three vectors, at every sample period, that fulfil the torque and flux demands. The predictive algorithm computes the torque error that would be present applying each vector and selects the one that contributes with the minimum error. Simulation results, which confirm the good performance of the novel predictive Direct Torque Control using Matrix Converters are shown.

In this paper, a novel design approach for a phase to sinusoid amplitude converter (PSAC) has been investigated. Two segments have been used to approximate the first sine quadrant. A first linear segment is used to fit the region near the zero point, while a second fourth-order parabolic segment is used to approximate the rest of the sine curve. The phase sample, where the polynomial changed, was chosen in such a way as to achieve the maximum spurious free dynamic range (SFDR). The invented direct digital frequency synthesizer (DDFS) has been encoded in VHDL and post simulation was carried out. The synthesized architecture exhibits a promising result of 90 dBc SFDR. The targeted structure is expected to show advantages for perceptible reduction of hardware resources and power consumption as well as high clock speeds.

A low-complexity direct digital frequency synthesizer based on linear interpolation method is presented in this paper. The proposed architecture employs a new technique to derive the slope coefficients at the first sample of each segment's interval thereby eliminating the ROM which stores those values. ROM elimination has resulted in significant logic element saving and simplified the whole DDFS structure. The proposed DDFS has been analyzed using MATLAB and tested over entire Nyquist frequency range. The spurious free dynamic range (SFDR) of synthesized sinusoid achieved is 84 dBc. The resultant low complexity architecture along with high spectral purity synthesized signal meets the specifications of recent portable battery-driven products. Zastosowana technika pozwala na uzyskanie współczynnika pochyłości już z pierwszą próbką każdego z interwałów segmentów, przez co eliminowana jest konieczność użycia pamięci ROM. Przeprowadzono symulacje proponowanego rozwiązania w pełnym zakresie częstotliwości Niquist'a. Działanie metody zostało porównane z innymi znanymi architekturami. (Nowe podejście do projektowania bezpośredniego syntezatora cyfrowego o małej złożoności).

The classical structure of linear interpolationbased phase-to-sine mapper (PSM) consists of at least two ROMs for polynomial coefficient storage. Other architectures may include extra ROM for storing residual errors. However, ROMs dissipate high power and occupy a significant amount of the die area. This study presents a new technique that eliminates the ROM by including the computation of segment initial coefficients in the hardware. Therefore, it becomes possible to trim down noticeable hardware resources. The proposed direct digital frequency synthesizer (DDFS) architecture has been encoded in VHDL and synthesized with Quartus II software. Post simulation results show that the proposed design is capable of achieving the theoretical spurious-free dynamic range (SFDR) upper bound when optimal polynomial coefficients are considered. For 32 piecewise linear segments, the SFDR of the synthesized sinusoid is 84.15 dBc. A ROM compression ratio of 597.3:1 was also achieved. The performance of the DDFS is compared with previously presented DDFS techniques and the results show that the proposed design has advantages of high ROM compression ratio and low hardware complexity.

Multiplier is one of the most inevitable arithmetic circuit in digital signal design. Multipliers dissipate high power and occupy significant amount of the die area. In this paper, a low-error architecture design of the pretruncated parallel multiplier is presented. The coefficients word length has been truncated to reduce the multiplier size. This truncation scaled down the gate count and shortened the critical paths of partial product array. The statistical errors of the designed multiplier are calculated for different pre-truncate values and compared. The multiplier is implemented using Stratix III, FPGA device. The post fitting report is presented in this paper, which shows a saving of 36.9 % in resources usage, and a reduction of 17 % in propagation time delay.

A low-complexity direct digital frequency synthesizer based on linear interpolation method is presented in this paper. The proposed architecture employs a new technique to derive the slope coefficients at the first sample of each segment's interval thereby eliminating the ROM which stores those values. ROM elimination has resulted in significant logic element saving and simplified the whole DDFS structure. The proposed DDFS has been analyzed using MATLAB and tested over entire Nyquist frequency range. The spurious free dynamic range (SFDR) of synthesized sinusoid achieved is 84 dBc. The resultant low complexity architecture along with high spectral purity synthesized signal meets the specifications of recent portable battery-driven products. Zastosowana technika pozwala na uzyskanie współczynnika pochyłości już z pierwszą próbką każdego z interwałów segmentów, przez co eliminowana jest konieczność użycia pamięci ROM. Przeprowadzono symulacje proponowanego rozwiązania w pełnym zakresie częstotliwości Niquist'a. Działanie metody zostało porównane z innymi znanymi architekturami. (Nowe podejście do projektowania bezpośredniego syntezatora cyfrowego o małej złożoności).

In this paper, a novel design approach for a phase to sinusoid amplitude converter (PSAC) has been investigated. Two segments have been used to approximate the first sine quadrant. A first linear segment is used to fit the region near the zero point, while a second fourth-order parabolic segment is used to approximate the rest of the sine curve. The phase sample, where the polynomial changed, was chosen in such a way as to achieve the maximum spurious free dynamic range (SFDR). The invented direct digital frequency synthesizer (DDFS) has been encoded in VHDL and post simulation was carried out. The synthesized architecture exhibits a promising result of 90 dBc SFDR. The targeted structure is expected to show advantages for perceptible reduction of hardware resources and power consumption as well as high clock speeds.

Savings Groups (SGs) are informal community-based entities that act as grassroots financial cooperatives. They provide financial services to their members over an agreed-upon time period, commonly referred to as a 'cycle'. During this cycle, saving and borrowing transactions take place during regular member meetings. Using new data on SGs worldwide, we conceptualize and quantify SG performance at the group level. Starting from the financial economics of the SG model, we introduce the savings capacity, profit-generating capacity, and borrowing conditions as complementary performance dimensions. We study these dimensions both across and within cycles to capture the financial efficiency of SGs. Our findings suggest that while SGs strengthen savings capacity over time, they primarily act as short-term cash-management vehicles. Groups prefer easy and affordable loans for emergencies over profit generation via micro-lending. The profit-generating capacity is curtailed by two major implementation restrictions, namely, loan-tying and unproductive periods at the beginning and end of the cycle. Based on our statistics, we formulate recommendations related to the cycle setup and lending policies.

Cryptographic co-processors are integral to the modern System-on-Chips. Flexibility in such designs serves dual purpose, i.e., it enables acceleration of different essential cryptographic primitives (Encryption/Authentication/Pseudo Random Number Generation (PRNG) ) and also results in design compaction via resource sharing. In this context, a novel resource-shared crypto-coprocessor, named AE$HA-3 is presented, which combines two National Institute of Standards and Technology (NIST) standardized algorithms, i.e., Advance Encryption Standard (AES) and Secure Hash Algorithm-3 (SHA-3). Due to algorithmic dissimilarities, so far no resource-shared implementation enabling AES key scheduling/ enc/dec and SHA-3 has been presented. AE$HA-3 exploits resource-sharing for area reduction, i.e., integration of Look-Up-Tables (I-Tables) for AES enc/dec; logical optimization of Six Input Equation (SixIE) for SHA-3; a Unified XOR Section to carry out both key whitening in AES and SHA-3 transformations. Furthermore, the AES key scheduling was performed using the same resource-shared hardware. The proposed AE$HA-3 on Xilinx Virtex FPGA family results in highest hardware efficiency in terms of Throughput per Slice (TPS), along with a 49.37% area consumption reduction, when compared against the smallest stand-alone implementations presented to date.

In this paper we describe the network of ground-based ultraviolet (UV) radiation monitoring stations in Belgium. The evolution of the entire network, together with the details of measuring instruments is given. The observed cumulative irradiations-UVB, UVA and total solar irradiation (TSI)-over the course of measurement for three stations-A northern (Ostende), central (Uccle) and a southern (Redu)-are shown. The longest series of measurement shown in this study is at Uccle, Brussels, from 1995 till 2014. Thus, the variation of the UV index, together with the variation of irradiations during summer and winter months at Uccle are shown as a part of this climatological study. The trend of UVB irradiance over the above mentioned three stations is shown. This UVB trend is studied in conjunction with the long-term satellite-based total column ozone value over Belgium, which shows two distinct trends marked by a change point. The total column ozone trend following the change point is posit...

Direct torque control based on space vector modulation (SVM-DTC) protects the DTC transient merits. Furthermore, it creates better quality steady-state performance in a wide speed range. The modified method of DTC using SVM improves the electrical magnitudes of asynchronous machines, such as minimizing the stator current distortions, the stator flux with electromagnetic torque without ripple, the fast response of the rotor speed, and the constant switching frequency. In this paper, the proposed method is based on two new control strategies for direct torque control with space vector modulation. First, fuzzy logic control is used instead of the PI torque and a PI flux controller to minimizing the torque error and to achieve a constant switching frequency. The voltages in the direct and quadratic reference frame ) ,V (V q d are achieved by fuzzy logic control. In this scheme, the switching capability of the inverter is fully utilized, which improves the system performance. Second, the close loop of stator flux estimation based on the voltage model and a low pass filter is used to counteract the drawbacks in the open loop of the stator flux such as the problems saturation and dc drift. The response of this new control strategy is compared with DTC-SVM. The experimental and simulation results demonstrate that the proposed control topology outperforms the conventional DTC-SVM in terms of system robustness and eliminating the bad outcome of dc-offset.

This paper presents an H.264 standard-compliant video encoder optimized for region-of-interest (ROI) based coding tuned to American Sign Language (ASL) videos. Encoding modes are developed which allow the encoder to allocate both rate and computational resources differently across the ROIs. An objective measure of intelligibility is included in an encoder parameter optimization by modifying a fast offline distortion-complexity optimization algorithm, resulting in parameter selections that demonstrate excellent rateintelligibility-complexity performance. These parameters can be stored in a look-up table for use by an online algorithm which selects parameters based on available computational resources. The resulting parameter selections improve the encoder speed by up to 21.2% with a small decrease in intelligibility over the x264 default parameter settings.

This paper presents an H.264 standard-compliant video encoder optimized for region-of-interest (ROI) based coding tuned to American Sign Language (ASL) videos. Encoding modes are developed which allow the encoder to allocate both rate and computational resources differently across the ROIs. An objective measure of intelligibility is included in an encoder parameter optimization by modifying a fast offline distortion-complexity optimization algorithm, resulting in parameter selections that demonstrate excellent rateintelligibility-complexity performance. These parameters can be stored in a look-up table for use by an online algorithm which selects parameters based on available computational resources. The resulting parameter selections improve the encoder speed by up to 21.2% with a small decrease in intelligibility over the x264 default parameter settings.

A simple spectral model of solar energy input to the sea surface was extended to incorporate space-borne data. The extension involved finding a method of determining aerosol optical thickness (on the basis of AVHRR data) and the influence of cloudiness ( ...

The service area of wireless network is divided into cell as shown in Figure .1a and 1.1b. Each cell has an assigned group of discrete channels from the available bandwidth. The base station (BS) is established in each cell. Subscribers in each cell use channels assigned to each cell. Every mobile unit (MU) in the cell communicates through the BS via a channel. A region initially served by a BS in a conventional mobile system is split into several cells, each of which has its own BS; it serves by a certain number of channels. The primary rule of a BS is to terminate the radio link in the network side of the user to network interface. In a small micro cell system, a distributed channel assignment function can be implemented in BS. BSs are connected to the switching network through the wired lines. The major requirement for the future mobile communication systems is high network capacity and flexibility to accommodate time varying communication network. The limited availability of the radio frequency spectrum or bandwidth is the main reason that the future cellular mobile systems must be efficiently employed channel assignment methods to increase network capacity and adapt to time varying traffic.

Knowledge of the spatial and temporal variability of surface soil water content (SWC) is important to understand the linkage between hydrological, ecological and geological processes in a region. Optical Earth observation (EO) data offer the possibility to retrieve surface soil water information, since an overall decrease of soil reflectance corresponds to increasing SWC. Sensitivity analysis of the combined leaf (PROSPECT) and canopy (SAILH) reflectance models (PROSAIL) to soil reflectance variations was carried out, and remote sensing and ground data from different experimental agricultural sites (ESA Spectra Barrax Campaigns (SPARC) 2004, ESA Airborne SAR and Optic Campaigns (AgriSAR) 2006 and participatory multi-level EO-assisted tools for irrigation water management and agricultural decision-support (PLEIADeS) 2007) were exploited. A simple look-up table (LUT) inversion technique was implemented to estimate canopy and soil variables. High negative relationships (r = -0.87) between the soil reflectance factor of the model and the measured SWC were found for several crop types and different locations exhibiting a low fractional vegetation cover (fCover). Even though quantification of SWC is difficult, the method could be useful to obtain relative SWC information, especially before the start and at the beginning of the growing season. Furthermore, the physically based estimation approach offers the possibility of getting information about soil and canopy characteristics concurrently from optical EO data. The methodology presented in this article may also represent a suitable complement in the retrieval of SWC from active microwave.

A foveated image is a non-uniform resolution image whose resolution is highest at a point (fovea) but falls off away from the fovea. It can be obtained from a uniform image through a space-variant smoothing process, where the width of the smoothing function is small near the fovea and gradually expanding as the distance from the fovea increases. We treat this process as an integral operator and analyze its kernel. This kernel is dominated by its diagonal in the wavelet bases and thus permits a fast algorithm for foveating images. In addition, the transformed kernel takes a simple form which can be easily computed using a look-up table. This is useful since in applications, the fovea changes rapidly. We describe an application of our approximation algorithm in image visualization over the Internet.

The hyperbolic and exponential functions are widely used in various applications in engineering fields such as machine learning, Internet of Things (IOT), signal processing, etc. To fulfill the needs of future applications effectively, this paper proposes a low-latency, low-power, acceptable accuracy, and low-cost architecture for computing the approximate exponential function e ±z and the hyperbolic functions sinh(z) and cosh(z) using a table-driven algorithm named Approximate Composited-Stair Function (ApproxCSF). By adopting a FPGA, the proposed design is realized and demonstrates significant improvements in terms of latency, hardware cost, power consumption, and MSE by 91%, 96%, 74%, and 99%, respectively, compared to the state-of-the-art. Xilinx Virtex-5/7 FPGAs have been employed throughout the functional verification and prototype processes. Compared to related works, it shows that the proposed architectures are much better for low-cost and low-latency computations of exponential and hyperbolic functions than CORDIC, stochastic computation, and the Look-up Table approaches. The source code is publicly available online https://github.com/AyadMDalloo/ApproxCSF.

Single pixel dynamic-range compression alters a particular input value to a unique output value -a look-up table. It is used in chemical and most digital photographic systems having S-shaped transforms to render high-range scenes onto low-range media. Post-receptor neural processing is spatial, as shown by the physiological experiments of Dowling, Barlow, Kuffler, and Hubel & Wiesel. Human vision does not render a particular receptor-quanta catch as a unique response. Instead, because of spatial processing, the response to a particular quanta catch can be any color. Visual response is scene dependent. | Stockham proposed an approach to model human range compression using low-spatial frequency filters. Campbell, Ginsberg, Wilson, Watson, Daly and many others have developed spatial-frequency channel models. This paper describes experiments measuring the properties of desirable spatial-frequency filters for a variety of scenes. Given the radiances of each pixel in the scene and the observed appearances of objects in the image, one can calculate the visual mask for that individual image. Here, visual mask is the spatial pattern of changes made by the visual system in processing the input image. It is the spatial signature of human vision. Low-dynamic range images with many white areas need no spatial filtering. High-dynamic-range images with many blacks, or deep shadows, require strong spatial filtering. Sun on the right and shade on the left requires directional filters. These experiments show that variable scenedependent filters are necessary to mimic human vision. Although spatial-frequency filters can model human appearances, the problem still remains that an analysis of the scene is still needed to calculate the scene-dependent strengths of each of the filters for each frequency.

We review 15 techniques for estimating missing values of net ecosystem CO 2 exchange (NEE) in eddy covariance time series and evaluate their performance for different artificial gap scenarios based on a set of 10 benchmark datasets from six forested sites in Europe. The goal of gap filling is the reproduction of the NEE time series and hence this present work focuses on estimating missing NEE values, not on editing or the removal of suspect values in these time series due to systematic errors in the measurements (e.g., nighttime flux, advection). The gap filling was examined by generating 50 secondary datasets with artificial gaps (ranging in length from single half-hours to 12 consecutive days) for each benchmark dataset and evaluating the performance with a variety of statistical metrics. The performance of the gap filling varied among sites and depended on the level of aggregation (native halfhourly time step versus daily), long gaps were more difficult to fill than short gaps, and differences among the techniques were more pronounced during the day than at night. The non-linear regression techniques (NLRs), the look-up table (LUT), marginal distribution sampling (MDS), and the semiparametric model (SPM) generally showed good overall performance. The artificial neural network based techniques (ANNs) were generally, if only slightly, superior to the other techniques. The simple interpolation technique of mean diurnal variation (MDV)

Color is a powerful attribute that is used to characterize objects for tracking and other surveillance tasks. Since color is dependent on ambient illumination and the imaging equipment, the reliability of color features decreases as the object moves through regions observed with different cameras and with different illumination conditions. Typically, this issue is addressed using alternative color spaces or highly simplified color transformation. In this paper, we propose a more methodical approach to achieving color consistency using colorimetric principles. We model the image analysis system as an observer and develop camera-specific transformations so that images of the same object appear similar to this observer. The transformations thus developed are approximated with 3D look-up tables for fast operation. Experimental results show improved color consistency even under two very different illumination conditions. The results are evaluated both qualitatively and in terms of the effect on a particle filter based object tracker.

-LUT-based color management system • Discussion about issues associated with profile-based color management systems • Describe alternative approach motivated by problem of visually matching two known display devices • Use model-based method to achieve goal • Propose realizing method with simple table look-up operations 2 / 32

The calculated rates of H 2 SO 4 -H 2 O binary homogeneous nucleation (BHN), which is the only nucleation mechanism currently widely used in global aerosol models, are well known to have large uncertainties. Recently, we have reduced the uncertainties in the BHN rates on the basis of a kinetic quasi-unary nucleation (KQUN) model, by taking into account the measured bonding energetics of H 2 SO 4 monomers with hydrated sulfuric acid dimers and trimers. The uncertainties were further reduced by using two independent measurements to constrain the equilibrium constants for monomer hydration. In this paper, we present updated BHN rate look-up tables derived from the improved KQUN model which can be used by anyone to obtain the BHN rates under given conditions. The look-up tables cover a wide range of key parameters that can be found in the atmosphere and laboratory studies, and their usage significantly reduces the computational costs of the BHN rate calculations, which is critical for multidimensional modeling. The look-up tables can also be used by those involved in experiments and field measurements to quickly assess the likeliness of BHN. For quick application, one can obtain the BHN rates and properties of critical clusters by browsing through the tables. A comparison of results based on the look-up tables with those from widely used classical BHN model indicates that, in addition to several orders of magnitude difference in nucleation rates, there also exists substantial difference in the predicted numbers of sulfuric acid molecules in the critical clusters and their dependence on key parameters.

Recently, we have shown that the binary homogeneous nucleation (BHN) of H 2 SO 4 and H 2 O can be treated as a quasi-unary nucleation (QUN) of H 2 SO 4 in the equilibrium with H 2 O vapor and have developed a kinetic H 2 SO 4 -H 2 O nucleation model, which simulates the dynamic evolutions of cluster distributions explicitly. In this paper we present improved and updated version of the QUN model, which has been modified through the incorporation of more rigorous thermodynamics of the cluster formation and the effect of the surface area of preexisting particles on nucleation rates. The difference in the model predictions of the improved and original QUN models is not dramatic; however, the improved QUN model is more consistent thermodynamically. The predicted BHN rates based on the QUN model are in good agreement with existing observations within the range of uncertainties. We also study the dependence of kinetic BHN rates on key input parameters and discuss the conditions in which the H 2 SO 4 -H 2 O homogeneous nucleation in the atmosphere may become significant. The nucleation rates look-up tables derived from the QUN model, which can be readily used to find the nucleation rates at given conditions, are presented. The look-up tables cover a wide range of key parameters that can be found in the ambient atmosphere, in the laboratory studies, and in the exhaust plumes. These look-up tables can be easily incorporated in multidimensional models to predict BHN rates, and they can be utilized directly for the analysis and interpretation of the observed nucleation events.

We demonstrate an efficient method of rendering alias-free synthetic images using precomputed convolution integrals. The method is based on the observation that a visible polygon fragment's contribution to an image is solely a function of its position and shape, and that within a reasonable level of accuracy, a limited number of shapes represent the majority of cases encountered in images commonly rendered. The convolution integral is precomputed for all pixels affected by the polygon fragment and is stored in a table. Completely visible fragments which are either triangular or trapezoidal produce two indices into the table. Most other fragments which are represented as differences of simple fragments. The remaining eases are characterized by a bit-mask for which each bit has a corresponding set of look up tables. The basic technique has been applied to several fundamentally different rendering algorithms. In addition, we illustrate a version of the newly introduced nonuniform sampling technique implemented in the same program, but with different table values.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

The possibility of using shape mixtures of randomly oriented spheroids for modeling desert dust aerosol light scattering is discussed. For reducing calculation time, look‐up tables were simulated for quadrature coefficients employed in the numerical integration of spheroid optical properties over size and shape. The calculations were done for 25 bins of the spheroid axis ratio ranging from ∼0.3 (flattened spheroids) to ∼3.0 (elongated spheroids) and for 41 narrow size bins covering the size parameter range from ∼0.012 to ∼625. The look‐up tables were arranged into a software package, which allows fast, accurate, and flexible modeling of scattering by randomly oriented spheroids with different size and shape distributions. In order to evaluate spheroid model and explore the possibility of aerosol shape identification, the software tool has been integrated into inversion algorithms for retrieving detailed aerosol properties from laboratory or remote sensing polarimetric measurements o...

A reliable and highly efficient ab initio tight-binding-like electronic structure calculation method is developed. The method starts from a similar approach outlined by Horsfield ͓Phys. Rev. B 56, 6594 ͑1997͔͒, but in this work, the integral evaluations for the exchange-correlation matrix elements are achieved with reasonable accuracy by higher-order many-center expansions. All the integrals are obtained by the use of look-up tables and the efficiency of the calculation is further improved by optimizing the way to choose the integrals in the look-up tables. Calculations on molecular properties ͑such as equilibrium geometries, dipole moments, and the reaction energies for hydrogenation reactions for a series of molecules containing H, C, N, and O atoms͒ show that the method thus developed can be used as a general tool for the electronic structure calculations.

Parameterized PSpice macromodels are developed in the paper for accurate simulation of spiral inductors and planar transformers. The macrodefinitions describing the models are presented. A verification of the developed macromodels is performed by comparison of the simulation results for the S-parameters using PSpice and measurement data given in [1, 6]. The developed macromodels can be used successfully in the RF circuit design process.

Venus nightside emission measurements of VIRTIS on Venus Express provide the opportunity of surface studies in the narrow near infrared atmospheric windows. The measurements as well as detailed new radiative transfer simulations show that radiance ratios in the emission windows between 1.0 and 1.35 m with respect to the 1.02 m window can be used to extract information about the

Numerical simulations are presented for a NACA0015 airfoil undergoing sinusoidal pitching motion. Three different approaches are presented: Navier-Stokes simulations with an alternating direction implicit time marching scheme, Navier-Stokes simulations with an iterative time marching scheme, and a strongly coupled viscous-inviscid interaction approach. Results are presented for three cases: steady case, attached flow, and moderate stall. Among these cases, the moderate stall case is further analyzed to assess the effects of grid density, numerical viscosity and transition on the computed results. It is found that all three methods give satisfactory results for the attached flow case. It is observed from the moderate stall case study that the transition point prediction plays a critical role in the prediction of airloads. The one -equation Spalart-Allmaras turbulence model used for moderate stall cases did not adequately predict the airloads, particularly the drag and pitching moment hysteresis. Finally, it is found that the combination of a coarse grid and high values of numerical viscosity can lead to thicker boundary layers and earlier separation, and can dramatically affect the computations.

This document summarizes research performed under the SNL LDRD entitled -Computational Mechanics for Geosystems Management to Support the Energy and Natural Resources Mission.‖ The main accomplishment was development of a foundational SNL capability for computational thermal, chemical, fluid, and solid mechanics analysis of geosystems. The code was developed within the SNL Sierra software system. This report summarizes the capabilities of the simulation code and the supporting research and development conducted under this LDRD.

This paper presents a closed-loop controller for speed regulation of a three-phase induction motor by means of
a Modbus network, which is compound only by industrial-purpose hardware, namely two programmable logic controllers,
a human-machine interface and a variable-frequency drive. This represents a step beyond the state of the art because the
results in similar works reported in the literature were obtained using personal computers, academic-purpose hardware
or a combination of both academic-industrial technologies. The speed regulation was achieved through a proportionalintegral
controller executed in a programmable logic controller, whose feedback was supplied by another similar device
completely dedicated to read and decode an industrial optical encoder; furthermore, the control signals were commanded
to the alternating current motor using a variable-frequency drive. The proposed control network was tested through diverse
regulation experiments, under different conditions, in order to assess its effectiveness and robustness. The obtained results
were successful in terms of accuracy of the speed set-point tracking in comparison to the most similar works of the
state of the art, namely zero steady-state error was achieved, 12 seconds earlier for 75% larger references and 22%
less RMSE than other works, which are the best results reported so far. Such successful achievements encourage the
later implementation of more advanced control techniques on three-phase-motor based industrial machinery using only
industrial-purpose hardware.

We introduce PixelFlex2, our newest scalable wall-sized, multi-projector display system. For it, we had to solve most of the difficult problems left open by its predecessor, PixelFlex, a proof-of-concept demonstration driven by a large, multi-headed SGI graphics system. PixelFlex2 retains the achievements of PixelFlex (high-performance through single-pass rendering, single-pixel accuracy for geometric blending with only casual placement of projectors), while adding a) higher performance and scalability with a Linux PC-cluster, b) ...

Surface brightness is a fundamental observational parameter of galaxies. We show, for the first time in detail, how it can be used to obtain photometric redshifts for galaxies, the µ-PhotoZ method. We demonstrate that the Tolman surface brightness relation, µ ∝ (1 + z) -4 , is a powerful tool for determining galaxy redshifts from photometric data. We develop a model using µ and a color percentile (ranking) measure to demonstrate the µ-PhotoZ method. We apply our method to a set of galaxies from the SHELS survey, and demonstrate that the photometric redshift accuracy achieved using the surface brightness method alone is comparable with the best color-based methods. We show that the µ-PhotoZ method is very effective in determining the redshift for red galaxies using only two photometric bands. We discuss the properties of the small, skewed, non-gaussian component of the error distribution. We calibrate µ r , (ri) from the SDSS to redshift, and tabulate the result, providing a simple, but accurate look up table to estimate the redshift of distant red galaxies.

In the paper different approaches used for creation of electric power transformers are discussed and main types of their mathematical models and macromodels are described. Mathematical model of transformer is created in the hybrid coordinate basis, and macromodel of the power transformer is developed using the "black box" approach in the form of state space equations, the features of such type models usage are analyzed. Streszczenie. W artykule opisano alternatywne podejścia do konstrukcji transformatorów i podstawowe rodzaje ich matematycznych model i makromodeli. Omówiono tworzenie matematycznego model transformatora w hybrydowym układzie współrzędnych i budowę makromodelu w postaci równań stanu z wykorzystaniem podejścia typu ,,czarna skrzynka". Przedyskutowano własności opracowanych modeli. (Matematyczne modele i makromodele transformatorów mocy)

This paper presents a genetic algorithm (GA) that solves the problem of routing a multiplexer network into a MUXTREE embryonic array. The procedure to translate the multiplexer network into a form suitable for the GAbased router is explained. The genetic algorithm works on a population of configuration registers (genome) that define the functionality and connectivity of the array. Fitness of each individual is evaluated and those closer to solving the required routing are selected for the next generation. A matrix-based method to evaluate the routing defined by each individual is also explained. The output of the genetic router is a VHDL program describing a look-up table that receives the cell co-ordinates as inputs and returns the value of the corresponding configuration register. The routing of a module-10 counter is presented as an example of the capabilities of the genetic router. The genetic algorithm approach provides not one, but multiple solutions to the routing problem, opening the road to a new level of redundancy where a new "genome" can be downloaded to the array when the conventional reconfiguration strategy runs out of spare cells.

Several recent techniques from hybrid and optimal control are evaluated on a power electronics benchmark problem. The benchmark involves a number of practically interesting operating scenarios for a fixed-frequency step-up dc-dc converter. The specifications are defined such that good performance can only be obtained if the switched and nonlinear nature of the problem is respected during the design phase.