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排序方式: 共有61条查询结果,搜索用时 15 毫秒
1.
We present a region of interest (ROI) generation method specialized for nighttime pedestrian detection using far-infrared (FIR) images. Because pedestrians typically appear brighter than background in FIR images, previous research efforts primarily attempted to extract ROIs based on the intensity threshold. However this approach has problems resulting from the intensity variances of pedestrians due to their clothing and, especially in urban scenarios, and other heat sources that emit more heat than the pedestrians. In this paper, we propose a novel ROI generation method that is based on combining image segments instead of using the intensity threshold. In order to minimize dependence on brightness, we utilize the low-frequency characteristics of FIR images. As a result, our proposed method generates a small number of ROIs at an acceptable miss rate and the generated ROIs provide advantages for classification because the pedestrians are satisfactorily arranged within a bounding box. Experiments conducted indicate that our proposed method performs reliably in urban scenarios. 相似文献
2.
Lin Yikun Luo Xizhang Qiu Bingzheng Pang Xiao 《International Journal of Infrared and Millimeter Waves》1989,10(12):1427-1440
The optimum operating parameters of miniature OPFIRL was studied theoretically and experimentally. The theoretical results were in pretty good agreement with experimental results except for 1.5cm laser. The transverse feedback effect plays an important role in the miniature OPFIRL. it's worthv to be funther studied. 相似文献
3.
Terahertz spectroscopy techniques for explosives detection 总被引:1,自引:0,他引:1
Megan R. Leahy-Hoppa Michael J. Fitch Robert Osiander 《Analytical and bioanalytical chemistry》2009,395(2):247-257
Spectroscopy in the terahertz frequency range has demonstrated unique identification of both pure and military-grade explosives.
There is significant potential for wide applications of the technology for nondestructive and nonintrusive detection of explosives
and related devices. Terahertz radiation can penetrate most dielectrics, such as clothing materials, plastics, and cardboard.
This allows both screening of personnel and through-container screening. We review the capabilities of the technology to detect
and identify explosives and highlight some of the critical works in this area. 相似文献
4.
I. Mukhopadhyay R. M. Lees W. Lewis-Bevan J. W. C. Johns F. Strumia G. Moruzzi 《International Journal of Infrared and Millimeter Waves》1987,8(11):1483-1502
High-resolution infrared (IR) and far infrared (FIR) Fourier transform absorption spectra have been employed to investigate assignments of FIR laser lines reported from optically-pumped13CH3OH. The spectroscopic measurements are used in conjunction with the reported IR pump and FIR laser frequencies to form closed combination loops for several systems, serving to confirm the assignments and in some cases to improve the accuracy of the FIR laser frequencies. Frequency predictions from combination differences are also presented for a number of potential new FIR laser lines. 相似文献
5.
In this paper, we report 30 THz measurements of ammonia in its excited, ν2 = 1, inversion state. These measurements include transition frequencies and pressure shifts (where significant enough to be observed). Included in the data are two forbidden and three ro-inversion transitions, as well as 18 transitions never directly measured before. The measurements were made with an all-solid-state, diode-laser, difference-frequency spectrometer. Using an innovative laser-frequency locking scheme, this spectrometer provided accurately determined and continuously tuned THz-frequencies without requiring accurate knowledge of the absolute laser frequencies. The details of the spectrometer’s frequency calibration is discussed. A global analysis of NH3 based on the available ground state, ν2 = 1 state, and ν2-band transitions was carried out, and the resulting set of recommended molecular effective-Hamiltonian parameters for ammonia is presented. In addition, calculated center frequencies and intensities for all possible transitions up to J = 20 between rotation, inversion, and vibration levels in the ground and ν2 = 1 states are included as supplementary material. 相似文献
6.
M. Marlo-Helle A. Harju R.M. Nieminen 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):286
We study ground states and far-infrared spectra (FIR) of two electrons in four-minima quantum-dot molecule in magnetic field by exact diagonalization. Ground states consist of altering singlet and triplet states, whose frequency, as a function of magnetic field, increases with increasing dot–dot separation. When the Zeeman energy is included, only the two first singlet states remain as ground states. In the FIR spectra, we observe discontinuities due to crossing ground states. Non-circular symmetry induces anticrossings, and also an additional mode above ω+ in the spin-triplet spectrum. In particular, we conclude that electron–electron interactions cause only minor changes to the FIR spectra and deviations from the Kohn modes result from the low-symmetry confinement potential. 相似文献
7.
David P. Kratz Martin G. Mlynczak Christopher J. Mertens Helen Brindley Larry L. Gordley Javier Martin-Torres Ferenc M. Miskolczi David D. Turner 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,90(3-4):323-341
A considerable fraction (>40%) of the outgoing longwave radiation escapes from the Earth's atmosphere-surface system within a region of the spectrum known as the far-infrared (wave-numbers less than 650 cm−1). Dominated by the line and continuum spectral features of the pure rotation band of water vapor, the far-infrared has a strong influence upon the radiative balance of the troposphere, and hence upon the climate of the Earth. Despite the importance of the far-infrared contribution, however, very few spectrally resolved observations have been made of the atmosphere for wave-numbers less than 650 cm−1. The National Aeronautics and Space Administration (NASA), under its Instrument Incubator Program (IIP), is currently developing technology that will enable routine, space-based spectral measurements of the far-infrared. As part of NASA's IIP, the Far-Infrared Spectroscopy of the Troposphere (FIRST) project is developing an instrument that will have the capability of measuring the spectrum over the range from 100 to 1000 cm−1 at a resolution of 0.6 cm−1. To properly analyze the data from the FIRST instrument, accurate radiative transfer models will be required. Unlike the mid-infrared, however, no inter-comparison of codes has been performed for the far-infrared. Thus, in parallel with the development of the FIRST instrument, an investigation has been undertaken to inter-compare radiative transfer models for potential use in the analysis of far-infrared measurements. The initial phase of this investigation has focused upon the inter-comparison of six distinct line-by-line models. The results from this study have demonstrated remarkably good agreement among the models, with differences being of order 0.5%, thereby providing a high measure of confidence in our ability to accurately compute spectral radiances in the far-infrared. 相似文献
8.
A. De Michele K. Bousbahi G. Carelli A. Moretti 《International Journal of Infrared and Millimeter Waves》2003,24(10):1649-1654
We have investigated CHD2OH methanol as source of far-infrared (FIR) laser radiation using the optical pumping technique. Our new waveguide pulsed CO2 laser, with peak powers as high as some kW, has allowed us to observe 12 new lines. Each of them is characterized in wavelength, relative polarization, intensity, optimum operating pressure and pump offset from the center of the exciting CO2 line. 相似文献
9.
Vidar Gudmundsson Ingibjrg Magnúsdttir Sigur
ur I. Erlingsson 《Physica E: Low-dimensional Systems and Nanostructures》1998,1(1-4)
We study the optical absorption of arrays of quantum dots and antidots in a perpendicular homogeneous magnetic field. The electronic system is described quantum mechanically using a Hartree approximation for the mutual Coulomb interaction of the electrons. The evolution of the absorption is traced from the homogeneous to the strongly modulated case identifying the ensuing collective modes, the magnetoplasmons, and their correlations with inherent length scales of the system. 相似文献
10.
Mahmoud Mollabashi R. M. Lees J. W. C. Johns 《International Journal of Infrared and Millimeter Waves》1993,14(9):1727-1753
The Fourier transform far-infrared (FTFIR) spectrum of CD3OH has been obtained from 40–220 cm–1 at a resolution of 0.002 cm–1, and partially analyzed. Numerousb-type branches have been assigned in the spectrum, ranging over torsional states fromn=0 to 3. The branches have been fitted toJ(J+1) power-series energy expansions in order to obtainJ-independent branch origins. These in turn have been fitted to the torsion-rotation Hamiltonian, and improved molecular constants have been obtained for the ground vibrational state. 相似文献