共查询到20条相似文献,搜索用时 31 毫秒
1.
E. Yu. Perlin A. V. Ivanov R. S. Levitskii 《Journal of Experimental and Theoretical Physics》2003,96(3):543-554
It is shown that the photon avalanche mechanism can be used for producing nonequilibrium electron-hole pairs by low-intensity IR light with a photon energy smaller than the energy gap of a semiconductor by a factor of 3–5. A type II heterostructure with deep quantum wells is proposed to be employed for this purpose. In the model under investigation, the photon avalanche effect is due to a combination of a cascade of one-and two-photon transitions and Auger-type transitions. 相似文献
2.
The temporal dynamics of initial stage of breakdown development in high-pressure gases, i.e., ionization avalanche initiation
and development, its transition to plasma avalanche and then to plasma streamer, is discussed. Simple formulas for times of
transitions between various breakdown stages and ionization front propagation velocities at individual stages are derived. 相似文献
3.
We have used a new experimental method to produce and deform three-dimensional monodisperse foams. Uniaxial deformation causes
transitions in the foam in which the number of close-packed bubble layers perpendicular to the direction of elongation changes
by one. We predict the critical strains at which such transitions occur by calculating the foam energy as a function of strain.
These calculations are approximate with simplifying assumptions regarding the geometry of the bubbles. The foam deforms by
nucleation and subsequent glide of dislocations which consist, in one configuration, of pairs of 12- and 16-faced cells along
a close-packed direction of the foam. We describe these line defects and identify the topological transformations that occur
in glide. These are neighbour switchings associated with a 4-sided face that rotates changing the adjacencies of the cells.
These T4 operations occur in an avalanche and cause movement of the dislocation while preserving its identity.
Received 16 July 2001 相似文献
4.
Sikharulidze I Dolbnya IP Fera A Madsen A Ostrovskii BI de Jeu WH 《Physical review letters》2002,88(11):115503
The dynamics of the layer-displacement fluctuations in smectic membranes have been studied by x-ray photon correlation spectroscopy (XPCS). We report transitions from an oscillatory damping regime to simple exponential decay of the fluctuations, both as a function of membrane thickness and upon changing from specular to off-specular scattering. This behavior is in agreement with recent theories. Employing avalanche photodiode detectors and the uniform filling mode of the synchrotron storage ring, the fast limits of XPCS have been explored down to 50 ns. 相似文献
5.
We have described a new probabilistic method for calculating and assessing lightning striking terrestrial explosive objects using a combined criterion for the emergence of upward streamer and leader discharges from the elements of the object being protected and lightning rods taking into account the probabilistic nature of the avalanche–streamer and streamer–leader transitions, the trajectories of a downward stepped lightning leader and lightning current. It has been shown that the disregard of possible formation of uncompleted streamer discharges from the elements of the object in the electric field of a downward lightning leader, which can ignite explosive emission, decreases the rated probability of the object being damaged by a lightning stroke by several times. 相似文献
6.
E. Yu. Perlin A. V. Ivanov R. S. Levitskii 《Journal of Experimental and Theoretical Physics》2005,101(2):357-366
A new mechanism of prebreakdown generation of electron-hole pairs is considered. It includes a cascade of interband multiphoton transitions as well as Auger-type processes involving two or three photons. A combination of these processes leads to the multiphoton avalanche effect. The threshold pumping radiation intensities required for triggering the avalanche mechanism lie in the range of 1011–1012W/cm2. The band population balance equations describing the kinetics of pair production are obtained and solved numerically. It is shown that the proposed mechanism of production of nonequilibrium electron-hole pairs is more effective than “conventional” multiphoton absorption for intensities exceeding the threshold values. 相似文献
7.
We introduce a sandpile model driven by degree on scale-free networks, where the perturbation is triggered at nodes with the same degree. We numerically investigate the avalanche behaviour of sandpile driven by different degrees on scale-free networks. It is observed that the avalanche area has the same behaviour with avalanche size. When the sandpile is driven at nodes with the minimal degree, the avalanches of our model behave similarly to those of the original Bak-Tang-Wiesenfeld (BTW) model on scale-free networks. As the degree of driven nodes increases from the minimal value to the maximal value, the avalanche distribution gradually changes from a clean power law, then a mixture of Poissonian and power laws, finally to a Poisson-like distribution. The average avalanche area is found to increase with the degree of driven nodes so that perturbation triggered on higher-degree nodes will result in broader spreading of avalanche propagation. 相似文献
8.
Strain Avalanches in Microsized Single Crystals:A Theoretical Study of the Relation between the Avalanche Size and Duration 下载免费PDF全文
《中国物理快报》2016,(9)
Single crystal micropillars deform via a sequence of discrete strain avalanches,observed as displacement jumps or stress drops.Here we develop a simple crystal plasticity model to provide a quantitative expression of the relation between avalanche duration and avalanche size.It is found that the avalanche durations in scale with the averaged avalanche sizes only hold for those larger magnitudes.We show that the theoretical predictions are capable of capturing the essential aspects of scaling behaviors from micro-compression tests. 相似文献
9.
10.
Aruev P. N. Belik V. P. Zabrodskii V. V. Kruglov E. M. Nikolaev A. V. Sakharov V. I. Serenkov I. T. Filimonov V. V. Sherstnev E. V. 《Technical Physics》2020,65(8):1333-1339
Technical Physics - We have designed a silicon avalanche photodiode for detecting vacuum ultraviolet radiation. The external quantum yield of a silicon avalanche photodiode has been investigated in... 相似文献
11.
José Jiun-Shian Wu Wei-Pang Chang Hsi-Chien Shih Chen-Tung Yen Bai Chuang Shyu 《BMC neuroscience》2014,15(1):1-17
Background
Cortical neurons display network-level dynamics with unique spatiotemporal patterns that construct the backbone of processing information signals and contribute to higher functions. Recent years have seen a wealth of research on the characteristics of neuronal networks that are sufficient conditions to activate or cease network functions. Local field potentials (LFPs) exhibit a scale-free and unique event size distribution (i.e., a neuronal avalanche) that has been proven in the cortex across species, including mice, rats, and humans, and may be used as an index of cortical excitability. In the present study, we induced seizure activity in the anterior cingulate cortex (ACC) with medial thalamic inputs and evaluated the impact of cortical excitability and thalamic inputs on network-level dynamics. We measured LFPs from multi-electrode recordings in mouse cortical slices and isoflurane-anesthetized rats.Results
The ACC activity exhibited a neuronal avalanche with regard to avalanche size distribution, and the slope of the power-law distribution of the neuronal avalanche reflected network excitability in vitro and in vivo. We found that the slope of the neuronal avalanche in seizure-like activity significantly correlated with cortical excitability induced by γ-aminobutyric acid system manipulation. The thalamic inputs desynchronized cingulate seizures and affected the level of cortical excitability, the modulation of which could be determined by the slope of the avalanche size.Conclusions
We propose that the neuronal avalanche may be a tool for analyzing cortical activity through LFPs to determine alterations in network dynamics. 相似文献12.
本文分析了高达10atm范围的XeCl激光脉冲雪崩放电过程,讨论了延迟效应对放电形成时间的影响,通过与XeCl激光脉冲雪崩放电实验结果的比较,导出临界雪崩通道长度约为1mm。
关键词: 相似文献
13.
The strength and stability properties of hierarchical load-bearing networks and their strengthened variants have been discussed
in a recent work. Here, we study the avalanche time distributions on these load-bearing networks. The avalanche time distributions
of the V-lattice, a unique realization of the networks, show power-law behaviour when tested with certain fractions of its
trunk weights. All other avalanche distributions show Gaussian peaked behaviour. Thus the V-lattice is the critical case of
the network. We discuss the implications of this result. 相似文献
14.
Turgut Tut Bayram Butun Mutlu Gokkavas Ekmel Ozbay 《Photonics and Nanostructures》2007,5(2-3):140-144
We report high performance solar-blind photodetectors with reproducible avalanche gain as high as 820 under ultraviolet illumination. The solar-blind photodetectors have a sharp cut-off around 276 nm. We improved the device performance by designing different epitaxial wafer structure with thinner active multiplication layer. We compare the resulting fabricated devices from these wafers in terms of dark current, photoresponse, avalanche gain performances. 相似文献
15.
《Physica A》2005,357(1):129-133
We analyze the scaling of avalanche precursors in the three-dimensional random fuse model by numerical simulations. We find that both the integrated and non-integrated avalanche size distributions are in good agreement with the results of the global load sharing fiber bundle model, which represents the mean-field limit of the model. 相似文献
16.
We investigate the effect of the electric-field profile on the gain-bandwidth product of avalanche photodetectors with separate absorption and multiplication. We show that for a given multiplication layer thickness the electric-field profile plays an important role in determining the gain-bandwidth product. The calculation results show that an increasing triangular electric-field profile yields a larger gain-bandwidth product than most other profiles for Si/InGaAs avalanche photodetectors. 相似文献
17.
Internal cancellation of spikes using two avalanche photodiodes in series for single photon detection 下载免费PDF全文
<正>We propose a method of improving the performance of InGaAs/InP avalanche photodiodes by using two avalanche photodiodes in series as single photon detectors for 1550-nm wavelength.In this method,the raw single photon avalanche signals are not attenuated,thus a high signal-to-noise ratio can be obtained compared with the existing results.The performance of the scheme is investigated and the ratio of the dark count rate to the detection efficiency is obtained to be 1.3×10~(-4) at 213 K. 相似文献
18.
We numerically investigate the avalanche dynamics of the Bak-Tang-Wiesenfeld sandpile model on directed small-world networks. We find that the avalanche size and duration distribution follow a power law for all rewiring probabilities p. Specially, we find that, approaching the thermodynamic limit (L→∞), the values of critical exponents do not depend on p and are consistent with the mean-field solution in Euclidean space for any p>0. In addition, we measure the dynamic exponent in the relation between avalanche size and avalanche duration and find that the values of the dynamic exponents are also consistent with the mean-field values for any p>0. 相似文献
19.
In this work we analyze the role of time scale separation between the external driving and the avalanche relaxation dynamics in a one-dimensional model of propagation of innovations among economic agents. When the time scales are separated the model presents a nonequilibrium roughening transition. We show that when avalanche overlapping is permitted, only a rough phase is observed. 相似文献
20.
In critical phenomena, many of the characteristic features encountered in higher dimensions such as scaling, data collapse and associated critical exponents are also present in one dimension. Likewise for systems displaying self-organised criticality. We show that the one-dimensional Bak–Tang–Wiesenfeld sandpile model, although trivial, does indeed fall into the general framework of self-organised criticality. We also investigate the Oslo ricepile model, driven by adding slope units at the boundary or in the bulk. We determine the critical exponents by measuring the scaling of the kth moment of the avalanche size probability with system size. The avalanche size exponent depends on the type of drive but the avalanche dimension remains constant. 相似文献