Apertures Of Different Sizes Research Articles

A versatile classification tool for galactic activity using optical and infrared colors

Context.The overwhelming majority of diagnostic tools for galactic activity are focused mainly on the classes of active galaxies. Passive or dormant galaxies are often excluded from these diagnostics, which usually employ emission-line features (e.g., forbidden emission lines). Thus, most of them focus on specific types of activity or only on one activity class, for example active galactic nucleus (AGN) galaxiesAims.In this work we used infrared and optical colors to build an all-inclusive galactic activity diagnostic tool that can discriminate between star-forming, AGN, low-ionization nuclear emission-line region, composite, and passive galaxies, and which can be used in local and low-redshift galaxies.Methods.We used the random forest algorithm to define a new activity diagnostic tool. As the ground truth for the training of the algorithm, we considered galaxies that have been classified based on their optical spectral lines. We explored classification criteria based on infrared colors from the first three WISE bands (bands 1, 2, and 3) supplemented with optical colors from theu, g, andrSDSS bands. From them, we sought the combination with the minimum number of colors that provides optimal results. Furthermore, to mitigate biases related to aperture effects, we introduced a new WISE photometric scheme that combines apertures of different sizes.Results.Using machine learning methods, we developed a diagnostic tool that accommodates both active and passive galaxies under one unified classification scheme using just three colors. We find that the combination ofW1-W2, W2-W3, and g-r colors offers a good performance, while the broad availability of these colors for a large number of galaxies ensures it can be applied to large galaxy samples. The overall accuracy is ~81%, and the achieved completeness for each class is ~81% for star-forming, ~56% for AGN, ~68% for LINER, ~65% for composite, and ~85% for passive galaxies.Conclusions.Our diagnostic represents a significant improvement over existing infrared diagnostics because it includes all types of active galaxies, as well as passive galaxies, extending their application to the local Universe. The inclusion of the optical colors improves its ability to identify low-luminosity AGN galaxies, which are generally confused with star-forming galaxies, and helps us identify cases of starbursts with extreme mid-infrared colors that mimic obscured AGN galaxies, a well-known problem for most infrared diagnostics.

Hybrid high-concentration photovoltaic system designed for different weather conditions

In this study, we propose a novel high-concentration photovoltaic (HCPV) cell by considering both the light leakage characteristics of the Fresnel-lens-based solar cell modules and the performance issues arising from cloud shading in practical use. We use our self-constructed systems to conduct field measurements for up to half a year under various environmental conditions. According to the acquired results, it was surprising to know that in the area other than the focusing area, the so-called light leakage region, there always bears illuminance of about 20,000–40,000 lx whether it is a sunny day or a cloudy day with different cloud conditions. Such an interesting result is caused by the light scattering of the clouds and the inherent leakage characteristic of a Fresnel lens. To prove this important finding, we simulated the illuminance of the Fresnel lens structure used in the measurement with apertures of different sizes to determine the detected area. In the laboratory, the diffuse plates were used to mimic the situation of varying cloud layer thicknesses. The trend of calculated and measured results fitted well with the field measurements. Also, the experimental and simulation results show that the round angle and draft facet of the Fresnel lens were responsible for light leakage. This finding prompted us to propose a hybrid high-concentration solar module in which more cost-effective polycrystalline silicon solar cells are placed around the high-efficiency wafer of HCPV to capture the dissipated light leakage and convert it into usable electricity.

Spatiotemporal statistics of the turbulent piston-removed phase and Zernike coefficients for two distinct beams.

In the context of adaptive optics for astronomy, one can rely on the statistics of the turbulent phase to assess a part of the system's performance. Temporal statistics with one source and spatial statistics with two sources are well known and widely used for classical adaptive optics systems. A more general framework, including both spatial and temporal statistics, can be useful for analysis of the existing systems and to support the design of future ones. In this paper, we propose an expression of the temporal cross power spectral densities of turbulent phases in two distinct beams, which is from two different sources to two different apertures. We consider the phase either as it is, without a piston, or as its decomposition on Zernike modes. The general formulas allow coverage of a wide variety of configurations, from single-aperture to interferometric telescopes equipped with adaptive optics, with the possibility to consider apertures of different sizes and/or sources at a finite distance. The presented approach should lead to similar results with respect to existing methods in the Fourier domain, but it is focused on temporal frequencies rather than spatial ones, which might be convenient for some aspects such as control optimization. To illustrate this framework with a simple application, we demonstrate that the wavefront residual due to the anisoplanatism error in a single-conjugated adaptive optics system is overestimated when it is computed from covariances without taking into account the temporal filtering of the adaptive optics loop. We also show this overestimation in the case of a small-baseline interferometer, for which the two beams are significantly correlated.

Pore-structure-enhanced electrochemical reduction of CO2 to formate on Sn-based double-layer catalysts

Sn-based materials can be used as electrocatalysts for the CO2 electroreduction reaction (CO2RR), preferentially producing formate. Although some Sn-based catalysts with a high faradaic efficiency for formate have been reported, the sensitivity of CO2RR activity to the catalyst structure remains elusive. Herein, a correlation between CO2RR activity and the geometric configuration of Sn-based catalysts was discovered using both double-shell SnOx nanospheres with apertures of different sizes, and CO2RR simulations using a three-step mechanism model. The kinetics analysis and simulation results suggest that a high loading of intermediate CO2,ads is the key to achieving high CO2RR performance with production of formate in the potential range −0.89 V ~ −1.26 V (vs. RHE). This understanding led to the design of double-shell SnOx nanospheres with enclosed apertures to increase the mesoporosity of the structure and hence its CO2 adsorption capability. Such a mechanism-guided approach to the design of catalysts not only enables a deep understanding of the CO2RR kinetics, but also sets a clear direction for the design of catalysts for scaled CO2RR applications.

The downsized hand in personal neglect

ABSTRACT Introduction: Personal neglect (PN) refers to a form of hemi-inattention toward the contralesional body space and it usually occurs following a right brain lesion. Recent studies suggest that PN indicates a disorder of body representation. Specifically, patients with PN show difficulties in identifying differences between left and right hands and have an altered visuospatial body map, which is associated with disrupted mental body representations. However, the metric representation of the body, and in particular the hands, has not been systematically addressed in patients showing this form of neglect. Method: In the present study, we have investigated this representation by testing the perceived hands’ width of 11 hemiplegic patients with right hemisphere cerebral lesions (5 with PN) and 12 healthy controls on a judgment of passability task. Patients and controls were asked to imagine inserting their hand (left and right) through a series of vertical apertures of different sizes and to judge whether their hand could fit through. Due to the heterogeneity of the data, both parametric and non-parametric approaches were used. Furthermore, additional single-case analyses were conducted. Results: Study findings showed that patients with PN showed a significant underestimation of the left hand compared with their right hand. In contrast, whilst the right hand was equally distorted in both patients’ groups, the hemiplegic patients with no evidence of PN tended to perceive the affected hand as larger than their ipsilesional one. Conclusions: In line with the literature, our findings confirm an underlying distorted body representation following right brain damage. However, for the first time, we report both a quantitative and qualitative difference in impact of hemiplegia and PN on body representation of the contralesional body space.

Turbulent Lidar: II−Experiment

Results of field experiments on horizontal paths using the BSA-2 and BSA-3 turbulent lidars, principles and design of which have been described in the first part, are presented. The BSA-2 lidar operated on 2-km path together with an independent image jitter sensor (IJS); and the BSA-3 lidar, on a horizontal 26-km path. The BSA-2 lidar was used in the experiments aimed at the study of the shape of the backscatter amplification peak, which was found to be 6.5 μrad in our experiments; the sounding was performed with apertures of different sizes. The experimental dependence of the q factor of the effect of turbulence on the size of receiving aperture is derived, which agrees satisfactorily with the Vorob’ev formula. The lidar sounding data and results of the data conversion into the structure parameter of the “optical” turbulence С 2 with the use of the Vorob’ev approximation for homogeneous turbulence are presented. The sounding range was ~10 km. The coefficient of correlation between lidar and IJS data is 0.7–0.8. The sounding in urban environment showed that a horizontal path is not statistically homogeneous; therefore, more complex procedures are to be used for the retrieval of the structure parameter С 2 when solving the inverse problems of lidar sounding of turbulence.

Numerical simulation of the coupling of ultra-wide band electromagnetic pulse into landmine by aperture**Project supported by the Postdoctoral Science Foundation of China (Grant No. 2014M552610).

The modern landmine’s electronic fuse is susceptible to strong interference or can even be damaged by the ultra-wide band electromagnetic pulse (UWB-EMP). The finite-difference time-domain (FDTD) method in lossy media with cylindrical coordinates is used to study the interactions of the UWB-EMP with the landmine. First, the coupling of UWB-EMP into the landmine shielding shell through an aperture is numerically simulated. Second, the coupled electromagnetic field of mine shells made of different shielding materials and with apertures of different sizes is plotted. Third, the aperture coupling laws of UWB-EMP into shells are analyzed and categorized. Such an algorithm is capable of effectively preventing ladder similar errors, and consequently improving the calculation precision, and in addition to adopting the message passing interface (MPI) parallel method to divide the total calculating range into more sub-ranges, the overall calculating efficiency is greatly increased. These calculations are surely a constructive reference for modern landmine design against electromagnetic damage.

Characteristics Analysis of Vacuum Gas Leak Detection Signals Based on Acoustic Emission

Gas leaks can cause major accidents resulting in both human injuries and financial losses. Vacuum pressureinduced air leaks lead to the emission of acoustic signals. Vacuum leak tests are implemented in this paper, and signals excited by leaks through apertures of three different diameters are investigated. According to the acoustic emission signal processing theory, several characteristic parameters were utilized to analyze the generation of continuous vacuum leakage acoustic emission signals. Applicable signal characteristics are used to distinguish the vacuumleaks through apertures of different sizes. It can be inferred that the acoustic emission method can detect vacuum gas leaks as they happen, and signal parameter characteristics analysis can be used to distinguish between the different aperture sizes. This paper is of practical significance to the work of acoustic emission vacuum leak detection.

Evaluation of uniformity for organic film evaporation using two dimensional different apertures

We have demonstrated an evaporation method to obtain a uniform organic thin-films with designed evaporation source which have array of two dimensional apertures of different sizes above an evaporation source optimized the distance between evaporation source and substrate, a uniform film was formed. Experimental results varying with position of the substrate are fitted to the theory of evaporation and the simulation of film uniformity using the uniform evaporation method was examined. In the simulation, different diameters of each apertures and distance between the evaporation source and the substrate were investigated. When the distance between the evaporation source and the substrate was 7 mm, adjusting the diameters of each apertures, the simulation uniform of film thickness of ±3.9 and ±1.0% at array of 3 × 3 and 9 × 9 apertures of different sizes was achieved in simulation, respectively. Moreover, in the evaporation experiment using array of 3 × 3 apertures, the uniformity of ±6.5% was obtained by photoluminescence measurement.

System for Measuring Planar Lipid Bilayer Properties

We present a system for measuring planar lipid bilayer properties. The system is composed of a control unit, an output stage, an LCR meter, pumps for filling reservoirs, a bath with temperature regulation and a measurement chamber with four electrodes. The planar lipid bilayer is automatically formed using a folding method on apertures of different sizes. The automatization is assured by two syringes, which are clamped in actuators. Actuators are driven and controlled by a control unit via RS-232 communication. The temperature of the planar lipid bilayer can be regulated between 15 and 55 °C. The regulation is assured by insertion of the measurement chamber into the temperature-regulated bath. Different shapes of voltage- or current-clamp signals can be applied to the planar lipid bilayer. By measuring the response of the planar lipid bilayer to the applied signal, the capacitance and breakdown voltage of the planar lipid bilayer can be determined. The cutoff frequencies of the system output stage for voltage- and current-clamp methods are 11 and 17 kHz, respectively.

Dynamics of extraclassical surround modulation in three types of V1 neurons

Visual stimuli outside of the classical receptive field (CRF) can influence the response of neurons in primary visual cortex (V1). While recording single units in cat, we presented drifting sinusoidal gratings in circular apertures of different sizes to investigate this extraclassical surround modulation over time. For the full 2-s stimulus time course, three types of neurons were found: 1) 68% of the cells were "suppressive," 2) 25% were "plateau" cells that showed response saturation with no suppression, and 3) the remaining 6% of cells were "facilitative." Analysis of the response dynamics revealed that at response onset, activity of one-half of facilitative cells, 70% of plateau cells, and all suppressive cells is suppressed by the surround. However, over the next 20-30 ms, surround modulation changes to stronger suppression for suppressive cells, substantial facilitation for facilitative cells, and weak facilitation for plateau cells. For all three cell types, these modulatory effects then stabilize between 100 and 200 ms from stimulus onset. Thus our findings illustrate two stages of surround modulation. Early modulation is mainly suppressive regardless of cell type and, because of rapid onset, may rely on feedforward mechanisms. Surround modulation that evolves later in time is not always suppressive, depending on cell type, and may be generated through different combinations of cortical circuits. Additional analysis of modulation throughout the cortical column suggests the possibility that the larger excitatory fields of facilitative cells, primarily found in infragranular layers, may contribute to the second stage of suppression through intracolumnar circuitry.

Comparison of Spatial Summation Properties of Neurons in Macaque V1 and V2

In visual cortex, responses to stimulation of the receptive field (RF) are modulated by simultaneous stimulation of the RF surround. The mechanisms for surround modulation remain unidentified. We previously proposed that in the primary visual cortex (V1), near surround modulation is mediated by geniculocortical and horizontal connections and far surround modulation by interareal feedback connections. To understand spatial integration in the secondary visual cortex (V2) and its underlying circuitry, we have characterized spatial summation in different V2 layers and stripe compartments and compared it to that in V1. We used grating stimuli in circular and annular apertures of different sizes to estimate the extent and sensitivity of RF and surround components in V1 and V2. V2 RFs and surrounds were twice as large as those in V1. As in V1, V2 RFs doubled in size when measured at low contrast. In both V1 and V2, surrounds were about fivefold the size of the RF and the far surround could exceed 12.5° in radius, averaging 5.5° in V1 and 9.2° in V2. The strength of surround suppression was similar in both areas. Thus although differing in spatial scale, the interactions among RF components are similar in V1 and V2, suggesting similar underlying mechanisms. As in V1, the extent of V2 horizontal connections matches that of the RF center, but is much smaller than the largest far surrounds, which likely derive from interareal feedback. In V2, we found no laminar or stripe differences in size and magnitude of surround suppression, suggesting conservation across stripes of the basic circuit for surround modulation.

A compact electron beam ion source with integrated Wien filter providing mass and charge state separated beams of highly charged ions

A Wien filter was designed for and tested with a room temperature electron beam ion source (EBIS). Xenon charge state spectra up to the charge state Xe46+ were resolved as well as the isotopes of krypton using apertures of different sizes. The complete setup consisting of an EBIS and a Wien filter has a length of less than 1 m substituting a complete classical beamline setup. The Wien filter is equipped with removable permanent magnets. Hence total beam current measurements are possible via simple removal of the permanent magnets. In dependence on the needs of resolution a weak (0.2 T) or a strong (0.5 T) magnets setup can be used. In this paper the principle of operation and the design of the Wien filter meeting the requirements of an EBIS are briefly discussed. The first ion beam extraction and separation experiments with a Dresden EBIS are presented.

Toward quantitative small animal pinhole SPECT: assessment of quantitation accuracy prior to image compensations.

We assessed the quantitation accuracy of small animal pinhole single photon emission computed tomography (SPECT) under the current preclinical settings, where image compensations are not routinely applied. The effects of several common image-degrading factors and imaging parameters on quantitation accuracy were evaluated using Monte-Carlo simulation methods. Typical preclinical imaging configurations were modeled, and quantitative analyses were performed based on image reconstructions without compensating for attenuation, scatter, and limited system resolution. Using mouse-sized phantom studies as examples, attenuation effects alone degraded quantitation accuracy by up to -18% (Tc-99m or In-111) or -41% (I-125). The inclusion of scatter effects changed the above numbers to -12% (Tc-99m or In-111) and -21% (I-125), respectively, indicating the significance of scatter in quantitative I-125 imaging. Region-of-interest (ROI) definitions have greater impacts on regional quantitation accuracy for small sphere sources as compared to attenuation and scatter effects. For the same ROI, SPECT acquisitions using pinhole apertures of different sizes could significantly affect the outcome, whereas the use of different radii-of-rotation yielded negligible differences in quantitation accuracy for the imaging configurations simulated. We have systematically quantified the influence of several factors affecting the quantitation accuracy of small animal pinhole SPECT. In order to consistently achieve accurate quantitation within 5% of the truth, comprehensive image compensation methods are needed.

Multiplexing in optical encryption by using an aperture system and a rotating sandwich random phase diffuser in the Fourier plane

In the present paper, we describe multiplexing in optical encryption of two-dimensional images, by using apertures and rotation of one of the constituent phase diffusers of a sandwich phase diffuser in the Fourier plane. The sandwich phase diffuser is made with two random constituent phase-diffusing surfaces sandwiched together. The apertures of different sizes and shapes are made with the help of ‘paint brush’ software. Simulation results are presented showing the effects of size, shape, and orientation of the apertures on the decrypted images obtained via multiplexing techniques. In addition to the results of using aperture systems in encryption and decryption, the results of rotation of one of the constituent phase diffusers in decryption are analyzed and used in multiplexing. Due to the use of aperture systems and the rotation of the constituent phase diffuser, the multiplexing capability of the system in encryption is enhanced along with the enhanced security due to using a sandwich diffuser. To evaluate the reliability of the technique, mean square error between the decrypted and the original image has been calculated.

Surface-plasmon-enhanced transmission through metallic film perforated with fractal-featured aperture array

A fractal-featured metallic thin film with Sierpinski Carpet pattern is fabricated on silicon wafer by microfabrication techniques. Transmission infrared spectroscopy indicates that there exists extraordinary high transmission at specific wavelengths, which can be ascribed to the effect of surface plasmon resonance, and are determined by hierarchy of apertures of different sizes in the fractal structure. This patterned film provides a unique system to achieve enhanced transmission simultaneously at different selected frequencies of electromagnetic wave.

Aperture averaging effects on the probability density of irradiance fluctuations in moderate-to-strong turbulence

The lognormal (LN) and gamma-gamma (GG) distributions are compared to simulated and experimental data of the irradiance fluctuations of a Gaussian beam wave propagating through the atmosphere along a horizontal path, near the ground, in the moderate-to-strong turbulence regime. Irradiance data were collected simultaneously at three receiving apertures of different sizes. Atmospheric parameters were inferred from the measurements and scintillation theory and were used to develop the parameters for the theoretical probability density functions. Numerical simulations were produced with the same C(n)(2) value as the experimental data. Aperture-averaging effects were investigated by comparing the irradiance distributions for the three apertures at two different values of the structure parameter C(n)(2), and, hence, different values of the coherence radius rho(0). For the moderate-to-strong fluctuation regime, the GG distribution provides a good fit to the irradiance fluctuations collected by finite-sized apertures that are significantly smaller than rho(0). For apertures larger than or equal to rho(0), the irradiance fluctuations appear to be LN distributed.

Tunable hydrophilicity on a hydrophobic fluorocarbon polymer coating on silicon

An efficient, economic, reliable, and repeatable patterning procedure of hydrophobic surfaces was developed. A fluorocarbon polymer derived from the C4F8 gas in an inductively coupled plasma etcher was used as the hydrophobic coating. For a subsequent patterning of hydrophilic apertures on the polymer, a short O2 plasma exposure through a silicon shadow mask was utilized. The overall hydrophilicity of the patterned surface can be tuned by the duration of the O2 plasma exposure, and also by the density and the size of the hydrophilic apertures. The laborious photolithography and tricky lift-off procedures are avoided. Optimization of the whole patterning process is explained thoroughly and supported with experimental data. The hydrophilic adhesion of the patterned polymer was evaluated with aqueous droplets, which were studied on matrices of the hydrophilic apertures of different sizes. The deposition parameters of the fluorocarbon polymer, the size of the droplet required to enable rolling on the patterned surface, and the duration of the O2 plasma exposure were considered as the main parameters. To determine the achievable resolution of the patterning procedure, the subsurface etching beneath the shadow mask was evaluated. The results show that a resolution of less than 10μm can be achieved. The simple hydrophilic patterning procedure described here can be used for the production of on-plane microfluidics, where a controlled adhesion or decohesion of 8–50μl droplets on the surface with a variable hydrophilicity from one location to another can be achieved.

Experimental investigation on the establishment of a spectral-radiance scale based on a copper-freezing-point black-body radiator

The spectral radiance of a black body can be calculated from Planck's radiation law when the black-body temperature is known. Therefore, the spectral radiance of a black-body radiator of accurately known temperature may be used as a reference for the establishment of a spectral radiance scale. In this paper we investigate the feasibility of using a copper-freezing-point (1357.77 K) black-body radiator to directly calibrate gas-filled tungsten strip-filament lamps operating at a radiance temperature of 2300 K (at 650 nm). A silicon photodetector with a variable-gain amplifier, as well as optical apertures of different sizes, were used to measure the large radiance ratios observed. The comparison was performed at eight wavelengths between 400 nm and 900 nm using interference filters. The major problem encountered was out-of-passband infrared (IR) leakage of the interference filters, particularly those below 550 nm. We discuss the use of sharp-cut glass filters to correct the IR leakage of the filters.

Polarimetric Observations of Comets C/1995 O1 Hale–Bopp and C/1996 B2 Hyakutake

We present polarimetric observations of Comet C/1995 O1 Hale–Bopp. Polarimetric data was obtained with a Pockels cell polarimeter at the Observatoire du Mont Mégantic, between July 1996 and May 1997. An intermediate bandpass red filter and five cometary filters, in the continuum and in emission bands, have been used. The comet was measured in linear and circular polarimetry, in the nuclear region and in the coma and tail, and through apertures of different sizes. The polarization was always parallel or perpendicular to the scattering plane within 4° or 5°. The curve of polarization as a function of the phase angle β has a steeper slope than usually seen in comets: a trigonometric fit gives 0.303±0.014% per degree. The crossover value of the phase angle, β co, is evaluated to be around 20°, which is typical for comets. Polarization and the angle of polarization show some variations when using different apertures and also as calculated in concentric rings centered on the nuclear region. Polarization was found to be significantly lower in the blue in the CO + and C 3 emission filters (426 and 406 nm) than in an adjacent 484-nm continuum filter and significantly higher in the red in the H 2O + emission filter (700 nm) than in the adjacent 684-nm continuum filter. Polarization has been measured in the coma and tail up to a distance of about 200″, corresponding to 2.2×10 5 km, in two continuum filters; the polarization increases and then decreases when going away from the nuclear region. Circular polarization at a maximum value of 0.2% was detected and was found to be variable. We present also a few observations of Comet C/1996 B2 Hyakutake that show that P max≈28.6% occurs at β≈91°.