Design of readout IC for photoelectron detector of short-wave high frequency IRFPA

2013 ◽  
Author(s):  
Pan Wang ◽  
Rui-jun Ding ◽  
Guo-qiang Chen ◽  
Honglei Chen
Keyword(s):  
High Frequency ◽  
Short Wave

Effect of rail pad stiffness on the wheel/rail force intensity in a railway slab track with short-wave irregularity

2019 ◽  
Vol 233 (10) ◽  
pp. 1038-1049 ◽  
Author(s):  
Amin Khajehdezfuly
Keyword(s):  
High Frequency ◽  
Critical Speed ◽  
Concrete Slab ◽  
Low Frequency ◽  
Short Wave ◽  
Vehicle Speed ◽  
Frequency Range ◽  
Slab Track ◽  
High Frequency Excitation ◽  
Frequency Excitation

In this paper, a two-dimensional numerical model is developed to investigate the effect of rail pad stiffness on the wheel/rail force in a slab track with harmonic irregularity. The model consists of a vehicle, nonlinear Hertz spring, rail, rail pad, concrete slab, resilient layer, concrete base, and subgrade. The rail is simulated using the Timoshenko beam element for considering the effects of high-frequency excitation produced by short-wave irregularity. The results obtained from the model are compared with those available in the literature and from the field to prove the validity of the model. Through a parametric study, the effect of variations in rail pad stiffness, vehicle speed, and harmonic irregularity on the wheel/rail force is investigated. For the slab track without any irregularity, the wheel/rail force is at maximum when the vehicle speed reaches the critical speed. As the rail pad stiffness increases, the critical speed increases. When the amplitude of irregularity is high, wheel jumping phenomenon may occur. In this situation, as the vehicle speed and rail pad stiffness are increased, the dynamic wheel/rail force is increased. In the low-frequency range, the wheel/rail force increases as the rail pad stiffness increases. In the high-frequency range, the wheel/rail force increases as the rail pad stiffness is decreased.

scholarly journals Flare-associated bursts at 18 Mc/s

1959 ◽  
Vol 9 ◽  
pp. 203-207
Author(s):  
Constance Warwick ◽  
J. W. Warwick
Keyword(s):  
High Frequency ◽  
Short Wave ◽  
Radio Noise

The occurrence of increased radio noise at the onset of short-wave fadeouts (SWF's) was noted by Appleton [1], who attributed the enhancements to solar emission. Payne-Scott [2], observing at about 19 Mc/s, measured burst intensities and times of occurrence to compare these high-frequency phenomena with radio events in the VHF range from 50 to 100 Mc/s.

The Interaction Between Steep Waves and a Vertical, Surface-Piercing Column

2005 ◽  
Vol 127 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Rizwan Sheikh ◽  
Chris Swan
Keyword(s):  
High Frequency ◽  
Impact Damage ◽  
Wave Interaction ◽  
Scattered Wave ◽  
Short Wave ◽  
Vertical Surface ◽  
Wave Impact ◽  
Single Column ◽  
High Frequency Waves ◽  
Incident Waves

This paper describes new laboratory observations concerning the interaction between a series of steep incident waves and a vertical, surface-piercing, column. The motivation for the study arose as a result of wave impact damage sustained to the undersides of several concrete gravity-based structures in the northern North Sea. Earlier work, [Swan et al. Appl. Ocean. Res. 19, pp. 309–327 (1997)], demonstrated that in the case of multiple column structures, the individual diameters of which lie outside the typical (linear) diffraction regime, there exists a new and previously unexpected mechanism leading to the scattering of high-frequency waves. Although the implications of this effect was carefully documented, not least because it explained the occurrence of wave impacts in relatively moderate seas, its physical origins remained unclear. In particular, it was uncertain whether this type of scattering would be observed in the case of a single column, or whether it results from the transmission of wave modes trapped between the legs of a multiple column structure. In the case of a single column, if the diameter, D, is such that the flow lies within the drag-inertia regime, D/λ<0.2, where λ is the corresponding wavelength, linear diffraction theory suggests there will be little or no scattered wave energy. The present laboratory observations demonstrate that this is not, in fact, the case. If the incident waves are steep, a strong and apparently localized interaction is clearly observed at the water surface. This, in turn, leads to the scattering of high-frequency waves. Although these waves are relatively small in amplitude, their subsequent interaction with other steep incident waves takes the form of a classic long-wave short-wave interaction and can produce a significant increase in the maximum crest elevation relative to those recorded in the absence of the structure. The present paper will demonstrate that the scattering of these high-frequency waves, and their subsequent nonlinear interaction with other incident waves, has significant implications for the specification of an effective air-gap and hence for the setting of deck elevations.

scholarly journals Observations of the Linear Polarization of Radio Sources at 6 cm Wavelength

1968 ◽  
Vol 21 (4) ◽  
pp. 493 ◽  
Author(s):  
D Morris ◽  
JB Whiteoak
Keyword(s):  
Linear Polarization ◽  
High Frequency ◽  
Wavelength Dependence ◽  
Radio Galaxies ◽  
Short Wave ◽  
Radio Sources ◽  
Polarization Data ◽  
Stellar Objects ◽  
Quasi Stellar Objects

The polarizations of 45 sources have been measured at 6 cm wavelength and have been compared with values obtained at longer wavelengths. The resulting wavelength dependence has been studied in relation to the spectra of the sources. For the quasi. stellar objects in particular, polarization features at short wave� lengths are associated with the young components of the source which radiate at high frequency. However, it is not possible to distinguish between radio galaxies and quasi-stellar objects solely on the basis of polarization data.

The Application of Track Spectrum Applying to Track Dynamic Analysis

2013 ◽  
Author(s):  
Cheng-hui Li ◽  
Bo-jing Chen ◽  
Yu-tao Liu ◽  
Feng Dai
Keyword(s):  
Dynamic Analysis ◽  
Time Domain ◽  
High Frequency ◽  
Short Wave ◽  
Statistical Characteristics ◽  
Track Structure ◽  
Actual Situation ◽  
Statistical Features ◽  
Track Irregularity ◽  
Original Type

The track irregularity is the primary cause to induce the vibration of the wheel-rail system. With the statistical characteristics of track irregularity, the track spectrum is widely applied to the track dynamic analysis. The track spectrum and its application are discussed in this paper mainly from the three aspects as follows. 1. Due to the multiple types of track structure, the statistical features of the track irregularity are varying, thus the original type and wavelength of the track spectrum cannot interpret the current situation. 2. As for the track dynamic analysis, because of the lack of the important short wave track irregularity spectrum, the track high-frequency vibration can hardly be further analysed with the existing track spectrum. 3. When the track irregularity in time domain included in the track spectrum for track dynamic analysis is used, there exists the problem that the amplitude of responses tends to be smaller than the actual situation. To sum up, this paper further put forward some suggestions about optimizing the test work of the supplementary track spectrum and reasonably utilizing the track spectrum.

The Interaction Between Steep Waves and a Vertical, Surface-Piercing Column

2003 ◽  
Author(s):  
Rizwan Sheikh ◽  
Chris Swan
Keyword(s):  
High Frequency ◽  
Impact Damage ◽  
Wave Interaction ◽  
Scattered Wave ◽  
Short Wave ◽  
Vertical Surface ◽  
Wave Impact ◽  
Single Column ◽  
High Frequency Waves ◽  
Incident Waves

The paper describes new laboratory observations concerning the interaction between a series of steep incident waves and a vertical, surface-piercing, column. The motivation for the study arose as a result of wave impact damage sustained to the undersides of several concrete gravity-based structures in the northern North Sea. Earlier work, Swan et al. [1], demonstrated that in the case of multiple column structures, the individual diameters of which lie outside the typical (linear) diffraction regime, there exists a new and previously unexpected mechanism leading to the scattering of high-frequency waves. Although the implications of this effect was carefully documented, not least because it explained the occurrence of wave impacts in relatively moderate seas, its physical origins remained unclear. In particular, it was uncertain whether this type of scattering would be observed in the case of a single column, or whether it results from the transmission of wave modes trapped between the legs of a multiple column structure. In the case of a single column, if the diameter, D, is such that the flow lies within the drag-inertia regime, D/λ &lt; 0.2, where λ is the corresponding wavelength, linear diffraction theory suggests there will be little or no scattered wave energy. The present laboratory observations demonstrate that this is not, in fact, the case. If the incident waves are steep, a strong and apparently localised interaction is clearly observed at the water surface. This, in turn, leads to the scattering of high-frequency waves. Although these waves are relatively small in amplitude, their subsequent interaction with other steep incident waves takes the form of a classic long-wave short-wave interaction and can produce a significant increase in the maximum crest elevation relative to those recorded in the absence of the structure. The present paper will demonstrate that the scattering of these high-frequency waves, and their subsequent nonlinear interaction with other incident waves, has significant implications for the specification of an effective air-gap and hence for the setting of deck elevations.

Регистрация высокочастотных рельефно-фазовых голографических структур на фотоматериале ПФГ-04

2021 ◽  
Vol 47 (21) ◽  
pp. 13
Author(s):  
Н.М. Ганжерли ◽  
С.Н. Гуляев ◽  
И.А. Маурер ◽  
А.В. Архипов
Keyword(s):  
Spatial Frequency ◽  
Uv Radiation ◽  
Diffraction Efficiency ◽  
High Frequency ◽  
Short Wave ◽  
Destructive Effect ◽  
Holographic Gratings ◽  
New Variant ◽  
First Time ◽  
Relief Phase

A new variant of processing photographic plates for holography based on dichromed gelatin PFG-04 (produced by JSC "Slavich Company", Pereslavl-Zalessky) for the manufacture of high-frequency relief–phase holographic gratings with a spatial frequency up to 1500 mm-1 is proposed. The technology is based on the selective destructive effect of short-wave UV radiation on gelatin and subsequent etching of the layer with various reagents. For the first time, relief-phase high-frequency holographic gratings with a maximum diffraction efficiency of 67% were obtained on PFG-04 photographic plates.

Short-Wave Orotrons and Oro-Multipliers

2010 ◽  
Vol 5 (4) ◽  
pp. 40-43
Author(s):  
Vladimir L. Bratman ◽  
Alexey E. Fedotov ◽  
Petr B. Makhalov ◽  
Fedor S. Rusin ◽  
Aleksandr N. Panin
Keyword(s):  
High Frequency ◽  
Frequency Doubling ◽  
Frequency Stability ◽  
Short Wave ◽  
Coherent Radiation ◽  
Frequency Multiplier ◽  
Alternative Source ◽  
Promising Alternative ◽  
Electron Bunches ◽  
Open Cavities

The capabilities of two types of terahertz sources based on stimulated Smith – Purcell radiation of electrons in open cavities are discussed. A series of developed pulsed orotrons provides coherent radiation at frequencies up to 410 GHz with an output power of 1–0.1 W with high frequency stability. A promising alternative source with smaller currents than in orotrons is a frequency multiplier based on the excitation of a surface wave of a periodic structure and Smith – Purcell radiation of arising electron bunches inside the orotron cavity. A possibility of frequency doubling inside the orotron cavity is experimentally demonstrated at a frequency of 190 GHz

Evaluation of Surface Vibrations in the Low and High Frequency Domain

1995 ◽  
Author(s):  
Peter Fischer ◽  
Helmut J. Pradlwarter ◽  
Gerhart I. Schuëller
Keyword(s):  
Frequency Domain ◽  
High Frequency ◽  
Flow Characteristics ◽  
Low Frequency ◽  
Structural Response ◽  
Short Wave ◽  
Fe Model ◽  
Special Cases ◽  
Wide Range ◽  
Surface Vibrations

Abstract The frequency domain of many problems in structural dynamics encompasses a wide range, covering nearly static behavior up to vibration flow characteristics similar to heat transfer. This work presents an uniform approach for low and high frequency vibration analysis, which is based on Finite Element modeling of the structure. Vibrations in the low frequency range are determined by an efficient superposition technique of complex modes, which accounts accurately for any linear damping effect. The modal method is extended to the high frequency domain by applying different levels of averaging to the response and eigenfrequencies and by the introduction of random properties of modeshapes. The high frequency domain is defined by the size of the Finite Elements, i.e. short wave lengths of high frequency modeshapes cannot be represented by the FE-model. The response computation of isolated structures is extended to substructures of complex systems by prescribing stochastic multi-support base excitation at the substructure boundaries. It may be noted, that the presented approach of stochastic high frequency dynamics contains, as special cases, the expressions of the structural response of Statistical Energy Analysis, Bolotin’s integral method and the results of Asymptotic Modal Analysis.

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