Spectral Points Research Articles

Calculation of radiative properties of SF6–C2F4 thermal plasmas—application to radiative transfer in high-voltage circuit breakers modelling

Radiative transfer is a key point for accurate simulations of arcs in high voltage circuit breakers where the plasma is mainly composed, at high current, of a mixture of SF6 and PTFE vapours (C2F4 and decomposition products). Assuming local thermodynamic equilibrium, we have built a database of absorption coefficients over almost 300 000 spectral points, for a pressure range between 1 and 100 bar, temperatures from 300 to 50 000 K, and proportions from pure SF6 to pure C2F4. From these data, we have calculated the mean absorption coefficients (MAC) by considering several definitions of the mean coefficient and several spectral ranges or intervals. The choice between the various definitions was operated using a one dimensional radiative transfer model with imposed temperature profiles. The results showed that a combination of a normal average over the molecular continuum at low temperature, with a mixed definition of Planck average at high temperature gives the most accurate results. The optimization of the number of intervals for the definition of the MAC database was performed and showed that the accuracy on the radiative flux and on the divergence of the flux depends on the temperature profile. A good compromise is obtained with five or seven intervals.

Studying competitive sorption behavior of methylene blue and malachite green using multivariate calibration

Sorption of methylene blue MB and malachite green MG (with 96.4% spectral overlap) from bi-solute solution by natural kaolinitic-clay and philipsite-rich-zeolite tuff was addressed where solutes simply quantified using multivariate calibration MVC. For simultaneous quantification of dyes in solution, partial least squares PLS1 (a powerful MVC tool) was found satisfactory with high recovery (98.7–103.2%) and precision (RSD 9.2–11.7%). In MVC, the spectral range 409–700nm is used and 43 spectral points where taken for each sample. Natural clay (80% kaolinite) and zeolite tuff (95% philipsite) showed a high uptake for dyes with maximum capacities of 0.77mmol MB/gclay and 0.64mmol MG/gclay, 0.66mmol MB/gzeolite and 1.22mmol MG/gzeolite reported at 1.0g/L, particle diameter <45μm, 20.0°C and pH 7.0. Due to competition between dyes for active sites, the sorption capacities were reduced and the highest reduction was 30% which observed for MG sorption by clay. The competition between dyes was higher in clay as indicated from competition factors CFs. Sorption isotherms of bi-solute systems have irregular L2 isotherm shape and the data were fairly correlated to Langmuir and competitive Langmuir models. The contribution of ion-exchange mechanism in dyes removal was found significant, 61% and 79% of MB were removed via ion-exchange by clay and zeolite, respectively. Using MVC, studying competitive sorption of MB and MG without the need for chromatographic separation is accomplished. Studying competitive sorption of more than two solutes using PLS1 is also possible indicating the high resolution power of this technique.

Information-technologycal support of post launch calibration of optoelectronic monitoring sensors of “Sich” space system

We consider the study results directed to creation in Ukraine of postlaunch metrological assurance of remote sensing systems based on developed evidence-based techniques, deployed land-based infrastructure of control and calibration polygon (CCP) systems with the test objects (TO) and measuring instruments and created software and hardware systems. The CCP infrastructure in the area of National Space Facilities Control and Test Center (NSFCTC) (Yevpatoriya-19) is ground, using as the standard template for describing the CCP approved by the Working Group on Calibration and Validation of the CEOS Committee. Based on the results of experiments to determine the spectral reflectance characteristics of the selected TO on ground-based measurements which are synchronous with satellite imagery of the space system (SS) “Sich-2”, GIS database is created. It contains the vector layers of polygonal natural and man-made objects of NSFCTC, layers of the spectral characteristics measurement points, satellite images of the SS “Quick Bird-2” and “Sich-2”, the digital terrain model of CCP. Such devices for ground-based measurements are analyzed, which must be equipped the test plots of polygon for control and calibration activities: 1) as the number of available to researchers: the digital weather station, spectrometers ASP-100F, ASD FieldSpec 3FR, equipment for precision measurements of the geodetic reference mark coordinates, 2) and the instruments used at the polygons of the LANDNET Sites System of CEOS Committee: CIMEL sun photometers in the AERONET CIMEL network, portable sun photometers MICROTOPS II, gonio radiometric spectrometer systems.

Resolvent convergence and spectral approximations of sequences of self-adjoint subspaces

This paper studies resolvent convergence and spectral approximations of sequences of self-adjoint subspaces (relations) in complex Hilbert spaces. Concepts of strong resolvent convergence, norm resolvent convergence, spectral inclusion, and spectral exactness are introduced. Fundamental properties of resolvents of subspaces are studied. By applying these properties, several equivalent and sufficient conditions for convergence of sequences of self-adjoint subspaces in the strong and norm resolvent senses are given. It is shown that a sequence of self-adjoint subspaces is spectrally inclusive under the strong resolvent convergence and spectrally exact under the norm resolvent convergence. A sufficient condition is given for spectral exactness of a sequence of self-adjoint subspaces in an open interval lacking essential spectral points. In addition, criteria are established for spectral inclusion and spectral exactness of a sequence of self-adjoint subspaces that are defined on proper closed subspaces.

Exponential stability of uniform Euler–Bernoulli beams with non-collocated boundary controllers

We study the stability of a robot system composed of two Euler–Bernoulli beams with non-collocated controllers. By the detailed spectral analysis, we prove that the asymptotical spectra of the system are distributed in the complex left-half plane and there is a sequence of the generalized eigenfunctions that forms a Riesz basis in the energy space. Since there exist at most finitely many spectral points of the system in the right half-plane, to obtain the exponential stability, we show that one can choose suitable feedback gains such that all eigenvalues of the system are located in the left half-plane. Hence the Riesz basis property ensures that the system is exponentially stable. Finally we give some simulation for spectra of the system.

Trace gas detection of benzene, toluene, p-, m- and o-xylene with a compact measurement system using cantilever enhanced photoacoustic spectroscopy and optical parametric oscillator

A compact measurement system based on a novel combination of cantilever enhanced photoacoustic spectroscopy (CEPAS) and optical parametric oscillator (OPO) was applied to the gas phase measurement of benzene, toluene, and o-, m- and p-xylene (BTX) traces. The OPO had a band width (FWHM) of 1.3nm, was tuned from 3237 to 3296nm in steps of 0.1nm and so spectra of BTX at different concentrations were recorded. The power emitted by the OPO increased from 88mW at 3237nm to 103mW at 3296nm. The univariate detection limits (3σ, 0.951s) for benzene, toluene, p-, m- and o-xylene at 3288nm were 12.0, 9.8, 13.2, 10.1 and 16.0ppb, respectively. Multivariate data analysis using science-based calibration was used to resolve the interference of the analytes. The multivariate detection limits (3σ, 3237–3296nm, 591 spectral points each 0.951s) for benzene, toluene, p-, m- and o-xylene in the multi-compound sample, where all other analytes and water interfere were 4.3, 7.4, 11.0, 12.5 and 6.2ppb, respectively. Without interferents, the multivariate detection limits varied between 0.5 and 0.6ppb. The sum of the cross-selectivities (3237–3296nm, 591 spectral points, each 0.951s) per analyte were below 0.05ppb/ppb, with an average of 0.038ppb/ppb. The cross-selectivity of water to the analytes was on average 1.22×10−4ppb/ppb. The OPO is small in size (L×W×H 125×70×45mm), commercially available, and easy to operate and integrate to setups. The combination with sensitive CEPAS enables compact measurement systems for industrial as well as environmental trace gas monitoring.

Construction of adaptive spectral analyzers on the basis of acousto-optic spectrometers

This paper discusses the problem of selecting the working spectral points in the method of selective spectral recording, used to detect contaminants in air by means of differential optical absorption spectroscopy on acousto-optic spectrometers with random spectral addressing. Reducing the number of recorded points of the spectrum, which allows the measurement time to be reduced by an order of magnitude, can simultaneously decrease the selectivity of the analysis, and this presents a problem if the composition of the impurity substances is unknown. A partial solution of the problem is proposed that consists of a preliminary study of the variations of the spectra of the gas mixture, and this makes it possible to statistically distinguish the main variable components in the composition of the gaseous mixture and to identify them with definite gases. Versions are proposed for the construction of adaptive systems based on acousto-optic spectrometers and using the technique developed here.

Analysis of transmittance properties of surface plasmon modes on periodic solid/outline bowtie nanoantenna arrays

We numerically analyze the transmittance properties of the periodic outline bowtie nanoantenna arrays and examine the nanoantenna resonance conditions compared to their solid counterparts by means of finite element method. Simulation results show that the structural parameters may affect the nanoantenna resonance conditions, such as peak resonance wavelengths, propagation properties, and charge densities at spectral points of interest. Besides, the essences of transmittance spectra of the periodic solid/outline bowtie nanoantenna arrays corresponding to their bonding mode and anti-bonding mode are investigated as well.

Paths to accuracy for radiation parameterizations in atmospheric models

Radiative transfer is sufficiently well understood that its parameterization in atmospheric models is primarily an effort to balance computational cost and accuracy. The most common approach is to compute radiative transfer with the highest practical spectral accuracy but infrequently in time and/or space, though errors introduced by this approximation are difficult to quantify. An alternative is to perform spectrally sparse calculations frequently in time using randomly chosen spectral quadrature points. Here we show that purely random quadrature points, though effective in some large‐eddy simulations, are not a good choice for models in which the land surface responds to radiative fluxes because surface temperature perturbations can be large enough, and persistent long enough, to affect model evolution. These errors may be mitigated by choosing teams of spectral points designed to limit the maximum surface flux error; teams, rather than individual quadrature points, are then chosen randomly. The approach is implemented in the ECHAM6 global model and the results are examined using “perfect‐model” experiments on time scales ranging from a day to a month. In this application the approach introduces errors commensurate with the infrequent calculation of broadband calculations for the same computational cost. But because teams need not increase with size, and indeed may become better and more balanced with increased spectral density, improvements in radiative transfer may not need to be traded off against spatiotemporal sampling.

Numerical simulation of a dispersion-managed active harmonically mode-locked fiber laser using a spectral double-grid technique

A comprehensive lumped model approach has been presented in this paper for the simulation of a dispersion-managed active mode-locked fiber laser. A key aspect of our model is that it operates simultaneously at two different spectral scales, corresponding to the gain bandwidth of the erbium-doped fiber and the frequency content of the mode-locked laser (MLL) pulse. The lumped model consists of a detailed amplifier model that is evolved using a predictor&#x2013;corrector-based adaptive approach. Convergence analysis of this algorithm is also presented in this paper, highlighting the step size reduction achieved when the amplifier migrates from linear to saturation regime. A simple adaptive frequency domain approach is followed to control the fine grid spectral points and the coarse grid wavelengths. Such an approach has been used to simulate a harmonic MLL cavity in two widely different dispersion regimes facilitated by a pair of chirped fiber Bragg gratings. We validate our model by comparing such simulated results with carefully planned experiments.

USING SATELLITE IMAGES FOR WIRELESS NETWORK PLANING IN BAKU CITY

Abstract. It is a well known fact that the Information-Telecommunication and Space research technologies are the fields getting much more benefits from the achievements of the scientific and technical progress. In many cases, these areas supporting each other have improved the conditions for their further development. For instance, the intensive development in the field of the mobile communication has caused the rapid progress of the Space research technologies and vice versa.Today it is impossible to solve one of the most important tasks of the mobile communication as Radio Frecance planning without the 2D and 3D digital maps. The compiling of such maps is much more efficient by means of the space images. Because the quality of the space images has been improved and developed, especially at the both spectral and spatial resolution points. It has been possible to to use 8 Band images with the spatial resolution of 50 sm. At present, in relation to the function 3G of mobile communications one of the main issues facing mobile operator companies is a high-precision 3D digital maps. It should be noted that the number of mobile phone users in the Republic of Azerbaijan went forward other Community of Independent States Countries. Of course, using of aerial images for 3D mapping would be optimal. However, depending on a number of technical and administrative problems aerial photography cannot be used. Therefore, the experience of many countries shows that it will be more effective to use the space images with the higher resolution for these issues. Concerning the fact that the mobile communication within the city of Baku has included 3G function there were ordered stereo images wih the spatial resolution of 50 cm for the 150 sq.km territory occupying the central part of the city in order to compile 3D digital maps. The images collected from the WorldView-2 satellite are 4-Band Bundle(Pan+MS1) stereo images. Such kind of imagery enable to automatically classificate some required clutter classes.Meanwhile, there were created 12 GPS points in the territory and there have been held some appropriate observations in these points for the geodesic reference of the space images in the territory. Moreover, it would like to mention that there have been constructed 37 permanently acting GPS stations in the territory of Azerbaijan at present. It significantly facilitates the process of the geodesic reference of the space images in order to accomplish such kind of mentioned projects. The processing of the collected space images was accomplished by means of Erdas LPS 10 program. In the first stage there was created the main component of the 3D maps- Digital Elevevation Model. In this model the following clutter classes are presented: Open; Open areas in urban; Airport, Sea, Inland water; Forest; Parks in urban; Semi Open Area; Open Wet Area; Urban/Urban Mean; Dense urban, Villages, Industrial/Commercial, Residential/Suburban; Dense residential/Suburban; Block of BUILDINGS; Dense Urban High; Buildings, Urban Mixed, Mixed dense urban

Sub-ppb detection of formaldehyde with cantilever enhanced photoacoustic spectroscopy using quantum cascade laser source

A novel cantilever enhanced photoacoustic spectrometer with mid-infrared quantum cascade laser was applied for selective and sensitive formaldehyde (CH2O) gas measurement. The spectrum of formaldehyde was measured from 1,772 to 1,777 cm−1 by tuning the laser with a spectral resolution of 0.018 cm−1. The band at 1,773.959 cm−1 was selected for data analysis, at which position the laser emitted 47 mW. In univariate measurement, the detection limit (3σ, 0.951 s) and the normalized noise equivalent absorption coefficient (3σ) for amplitude modulation (AM) were 1.6 ppbv and 7.32 × 10−10 W cm−1 (Hz)−1/2 and for wavelength modulation (WM) 1.3 ppbv and 6.04 × 10−10 W cm−1 (Hz)−1/2. In multivariate measurement, the detection limit (3σ) can be as low as 901 pptv (1,773.833–1,774.085 cm−1, 15 spectral points each 0.951 s) for AM and 623 pptv (1,773.743–1,774.265 cm−1, 30 spectral points each 0.951 s) for WM. Because measurement time increases in multivariate measurement, its application is justified only when interferents need to be resolved. Potential improvements of the system are discussed.

Localized SVEP, Property (b) and Property (ab)

Property (b) for a bounded linear operator \({T \in L(X)}\) on a Banach space X means that the points λ of the approximate point spectrum for which λI – T is upper semi-Weyl are exactly the spectral points λ for which λI – T is Browder. In this paper we shall give several characterizations of operators T for which T, or its dual T*, has property (b). We also investigate the property (ab) which is closely related to property (b).

Future plans for the Telescope Array experiment

The Telescope Array (TA) experiment is world's first and only air shower detector to be directly calibrated by an on-site accelerator beam. For wider and deeper understanding of cosmic rays via high precision measurements, we have several future plans for TA experiment. The first extension plan is an on-going project, called as TA low energy extension (TALE), to extend sensitive energy range to 10 16.5 eV in order to study second knee, predicted galactic-extragalactic transition of dominant sources and air shower phenomena comparing with LHC measurements. The second proposition is exchanges of FDs and SDs between TA and Pierre Auger Observatory, toward understanding systematic uncertainties of these experiments and to solve discrepancies in energy scales and Xmax. The third plan is a huge air shower array, the world observatory, consisting of a huge number of SDs and/or FDs for world's largest exposure and finest accuracy to open a new window on astronomy with ultra high energy particles. surface detectors (SDs) arrayed with a spacing of 1.2km between each SD in an area of approximately 680km 2 , and air fluorescence detectors (FDs) in three stations located around SDs facing inward and looking over array. The full operation of detectors have been started in March 2008. In TA experiment we have most valuable calibration facility which is a electron linear accelerator, called Electron Light Source (ELS) (2). ELS installed 100m away from south-east FD station (called BRM station) shoots calibrated electron beams for FDs. The typical energy per electron and number of electrons are 40MeV and 10 9 , respectively. With this equipment we will achieve an end to end calibration for FDs. After four years of very stable operations, we have successfully released our results in this conference, although some of these are still preliminary. The results are briefly summarized as follows: The energy spectrum has a clear ankle at 10 18.7 eV and a sharp cutoff above 10 19.7 eV. The flux is consistent with HiRes result. The shape of spectrum curve, it means spectral indexes and break points on curve, are fitted to spectrum curves by HiRes and that by Auger, However, to fit our curve with that by Auger we need to shift primary energies about 20%. Our preliminary results of mass composition analyses, which are averaged Xmax and their distributions, show that protons dominate primary composition of observed showers. This preliminary conclusion contradicts Auger's results (3), which show a transition of dominant composition from light to heavy, derived from averaged Xmax values and their distributions. From arrival direction distribution analyses, we do not observe

ANALYSIS OF A WIDE SPECTRAL RANGE PLASMONIC OUTLINE BOWTIE ANTENNA RANGING IN 0.3-5.0 μm

We numerically analyze a broadband plasmonic outline bowtie antenna over a large parameter space by means of finite element method with three-dimensional calculation. The antenna is composed of a pair of triangular gold with outline shape placed in close proximity to each another. We show how the structural parameters affect the antenna resonance conditions, such as peak resonances wavelengths, electric field intensities, propagation properties, component field and total field distributions, charge densities and electrical filed stream lines at spectral points of interest. In addition, the characteristics of transmittance spectral of a periodic antenna array corresponding to the bonding mode and anti-bonding mode are investigated as well. Simulation results show that it is possible to tune an antenna with a constant length over a wide spectral range (ranging in 0.3–5.0μm or more range) while maintaining a constant antenna dimension, reduce the antenna footprint by a factor of 4.98, and increase the gap enhancement by 23%. This article has been removed from the website on January 3, 2013, because it has been found to violate plagiarism rule of our journal. Received 18 October 2012, Accepted 16 November 2012, Scheduled 7 December 2012 * Corresponding author: Yuan-Fong Chau (yfc01@uch.edu.tw).

Weyl's Theorems and Extensions of Bounded Linear Operators

A bounded operator $T\in L(X)$, $X$ a Banach space, is said to satisfy Weyl's theorem if the set of all spectral points that do not belong to the Weyl spectrum coincides with the set of all isolated points of the spectrum which are eigenvalues and having finite multiplicity. In this article we give sufficient conditions for which Weyl's theorem for an extension $\overline T$ of $T$ (respectively, for $T$) entails that Weyl's theorem holds for $T$ (respectively, for $\overline T$).

Soil surface spectral data from Landsat imagery for soil class discrimination

The aim of this study was to develop and test a method to determine and discriminate soil classes in the state of Sao Paulo, Brazil, based on spectral data obtained via Landsat satellite imagery. Satellite reflectance images were extracted from 185 spectral reading points, and discriminant equations were obtained to establish each soil class within the studied area. Sixteen soil classes were analyzed, and discriminant equations that comprised TM5/Landsat sensor bands 1, 2, 3, 4, 5, and 7 were established. The results showed that this methodology could effectively identify individual soil classes using discriminant analyses of the spectral data obtained from the surface. Success rates of > 40% were achieved for 14 of the 16 evaluated soil classes when applying the satellite image data. When the 10 soil classes containing the largest number of minimum cartographic areas were used, the hit rate increased to > 50%, for seven soil classes with a global hit rate of 52%. When the soil classes were grouped based on their parent materials, the hit rate increased to 70%. Thus, we concluded that the spectral method for soil classification was efficient.

Functional relationships for investigating cognitive processes

Functional relationships (from systematic manipulation of critical variables) are advocated for revealing fundamental processes of (comparative) cognition—through examples from my work in psychophysics, learning, and memory. Functional relationships for pigeon wavelength (hue) discrimination revealed best discrimination at the spectral points of hue transition for pigeons—a correspondence (i.e., functional relationship) similar to that for humans. Functional relationships for learning revealed: Item-specific or relational learning in matching to sample as a function of the pigeons’ sample-response requirement, and same/different abstract-concept learning as a function of the training set size for rhesus monkeys, capuchin monkeys, and pigeons. Functional relationships for visual memory revealed serial position functions (a 1st order functional relationship) that changed systematically with retention delay (a 2nd order relationship) for pigeons, capuchin monkeys, rhesus monkeys, and humans. Functional relationships for rhesus-monkey auditory memory also revealed systematic changes in serial position functions with delay, but these changes were opposite to those for visual memory. Functional relationships for proactive interference revealed interference that varied as a function of a ratio of delay times. Functional relationships for change detection memory revealed (qualitative) similarities and (quantitative) differences in human and monkey visual short-term memory as a function of the number of memory items. It is concluded that these findings were made possible by varying critical variables over a substantial portion of the manipulable range to generate functions and derive relationships.

A comparison of convex and non-convex compressed sensing applied to multidimensional NMR

The resolution of multidimensional NMR spectra can be severely limited when regular sampling based on the Nyquist–Shannon theorem is used. The theorem binds the sampling rate with a bandwidth of a sampled signal and thus implicitly creates a dependence between the line width and the time of experiment, often making the latter one very long. Recently, Candès et al. (2006) [25] formulated a non-linear sampling theorem that determines the required number of sampling points to be dependent mostly on the number of peaks in a spectrum and only slightly on the number of spectral points. The result was pivotal for rapid development and broad use of signal processing method called compressed sensing. In our previous work, we have introduced compressed sensing to multidimensional NMR and have shown examples of reconstruction of two-dimensional spectra. In the present paper we discuss in detail the accuracy and robustness of two compressed sensing algorithms: convex (iterative soft thresholding) and non-convex (iteratively re-weighted least squares with local ℓ0-norm) in application to two- and three-dimensional datasets. We show that the latter method is in many terms more effective, which is in line with recent works on the theory of compressed sensing. We also present the comparison of both approaches with multidimensional decomposition which is one of the established methods for processing of non-linearly sampled data.

Self-assembly of gelator molecules in liquid crystals studied by ESR

Thermotropic liquid crystal trans-4-heptylcyclohexanecarboxylic acid (HCCA) doped with 4-oxo-2,2,6,6,-tetramethyl-1-piperidinyloxy spin probe (Tempone) is investigated by electron spin resonance (ESR) spectroscopy in the presence of chiral bisoxalamide gelator 1 during both cooling and heating cycles. In the temperature range 295–383K, where HCCA displays isotropic, nematic, smectic B and crystalline phases, the impact of 1 self-organization was detected via (non) homogeneous partitioning of the spin probe in the environments varying in the polarity, an effect dependent on the gelator concentration. In particular, the evidence of the onset of the gelator network self-assembly in the nematic phase was detected by ESR at higher temperatures than the ones reported so far by other experimental techniques. Additionally, the spectral analysis points to the switching of the polarity in the vicinity of the spin probe when the transfer of chirality from 1 to HCCA upon cooling of the sample from isotropic to chiral nematic phase appears and when the event of LC gelation results in the achiral nematic phase during chiral gel fibers formation. When the gelation proceeds in the smectic phase, the melting of the gelator network is studied in the nematic phase during the heating cycle. Furthermore, the event of HCCA crystallization is shown to be strongly affected by the presence of 1 as well. The experimental evidence is provided that gelator network confines the HCCA into the domains within the bulk crystalline matrix where the local molecular dynamics are still not frozen. Therefore, we propose that non-homogeneous polarity profile of molecular organization/packing within LC gels could be determinable for the physical properties of various LC gel phases.