A Priority-Based Defragmentation Scheme in Flexible Bandwidth Optical Networks

2012 ◽  
Vol 198-199 ◽  
pp. 1632-1637
Author(s):  
Jie Zhao ◽  
Yong Li Zhao ◽  
Xiao Song Yu ◽  
Xin Bo Wang
Keyword(s):  
Optical Networks ◽  
Narrow Band ◽  
Broad Band ◽  
Wdm Networks ◽  
Critical Problem ◽  
Lower Block ◽  
Simulation Results ◽  
A Priority ◽  
Path Lengths ◽  
Priority Levels

Flexible Bandwidth Optical Networks(FBON) can improve spectrum usage rates comparing to traditional WDM networks, leaving one critical problem of spectrum fragments. This paper proposes a novel defragmentation scheme that determines the sequence of connections going through defragmentation processes. In sequencing connections, priority zones are divided and priority levels are set accordingly. Bandwidths or path lengths are what make a difference in a connection’s priority. As simulation results show, priority-based defragmentation scheme can achieve lower block rates as well as lower interruption rates. The simulation results also prove the preference of local defragmentation to global defragmentation and the preference of narrow-band defragmentation to broad-band defragmentation.

A Simulation-Based Performance Study on Concurrent Multi-Path Transmission over Wireless Broad-Band Network

2014 ◽  
Vol 513-517 ◽  
pp. 2228-2231
Author(s):  
Jing Ji Jin ◽  
Lin Cui ◽  
Xin Cui ◽  
Woo Jin Lee ◽  
Seok J. Koh
Keyword(s):  
Narrow Band ◽  
Broad Band ◽  
Multimedia Transmission ◽  
Performance Study ◽  
Simulation Based ◽  
Simulation Results

The previous studies showed that the concurrent multi-path transmission (CMT) schemes can only play their advantage in the narrow-band networks (the most CMT experiments use 2M bandwidth). In this paper, the authors investigate the performance profits of CMT schemes with various network bandwidths. The simulation results show that the CMT schemes can work better in broad-band networks (e.g., over 20M bandwidth) than in narrow-band networks. This also implies that the CMT schemes have the potential to be applied in the field of multimedia transmission.

scholarly journals Automated detection and association of surface waves

1994 ◽  
Vol 37 (3) ◽  
Author(s):  
R. G. North ◽  
C. R. D. Woodgold
Keyword(s):  
Surface Waves ◽  
Group Velocity ◽  
Rayleigh Waves ◽  
Arrival Time ◽  
Narrow Band ◽  
Broad Band ◽  
Detection Algorithm ◽  
Automated Detection ◽  
Short Period ◽  
Group Velocities

An algorithm for the automatic detection and association of surface waves has been developed and tested over an 18 month interval on broad band data from the Yellowknife array (YKA). The detection algorithm uses a conventional STA/LTA scheme on data that have been narrow band filtered at 20 s periods and a test is then applied to identify dispersion. An average of 9 surface waves are detected daily using this technique. Beamforming is applied to determine the arrival azimuth; at a nonarray station this could be provided by poIarization analysis. The detected surface waves are associated daily with the events located by the short period array at Yellowknife, and later with the events listed in the USGS NEIC Monthly Summaries. Association requires matching both arrival time and azimuth of the Rayleigh waves. Regional calibration of group velocity and azimuth is required. . Large variations in both group velocity and azimuth corrections were found, as an example, signals from events in Fiji Tonga arrive with apparent group velocities of 2.9 3.5 krn/s and azimuths from 5 to + 40 degrees clockwise from true (great circle) azimuth, whereas signals from Kuriles Kamchatka have velocities of 2.4 2.9 km/s and azimuths off by 35 to 0 degrees. After applying the regional corrections, surface waves are considered associated if the arrival time matches to within 0.25 km/s in apparent group velocity and the azimuth is within 30 degrees of the median expected. Over the 18 month period studied, 32% of the automatically detected surface waves were associated with events located by the Yellowknife short period array, and 34% (1591) with NEIC events; there is about 70% overlap between the two sets of events. Had the automatic detections been reported to the USGS, YKA would have ranked second (after LZH) in terms of numbers of associated surface waves for the study period of April 1991 to September 1992.

scholarly journals Thalamic inputs determine functionally distinct gamma bands in mouse primary visual cortex

2020 ◽  
Author(s):  
Nicolò Meneghetti ◽  
Chiara Cerri ◽  
Elena Tantillo ◽  
Eleonora Vannini ◽  
Matteo Caleo ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Information ◽  
Narrow Band ◽  
Broad Band ◽  
Gamma Band ◽  
Neuron Network ◽  
Sensory Stimuli ◽  
Thalamic Input ◽  
Visual Contrast

AbstractGamma band is known to be involved in the encoding of visual features in the primary visual cortex (V1). Recent results in rodents V1 highlighted the presence, within a broad gamma band (BB) increasing with contrast, of a narrow gamma band (NB) peaking at ∼60 Hz suppressed by contrast and enhanced by luminance. However, the processing of visual information by the two channels still lacks a proper characterization. Here, by combining experimental analysis and modeling, we prove that the two bands are sensitive to specific thalamic inputs associated with complementary contrast ranges. We recorded local field potentials from V1 of awake mice during the presentation of gratings and observed that NB power progressively decreased from low to intermediate levels of contrast. Conversely, BB power was insensitive to low levels of contrast but it progressively increased going from intermediate to high levels of contrast. Moreover, BB response was stronger immediately after contrast reversal, while the opposite held for NB. All the aforementioned dynamics were accurately reproduced by a recurrent excitatory-inhibitory leaky integrate-and-fire network, mimicking layer IV of mouse V1, provided that the sustained and periodic component of the thalamic input were modulated over complementary contrast ranges. These results shed new light on the origin and function of the two V1 gamma bands. In addition, here we propose a simple and effective model of response to visual contrast that might help in reconstructing network dysfunction underlying pathological alterations of visual information processing.Significance StatementGamma band is a ubiquitous hallmark of cortical processing of sensory stimuli. Experimental evidence shows that in the mouse visual cortex two types of gamma activity are differentially modulated by contrast: a narrow band (NB), that seems to be rodent specific, and a standard broad band (BB), observed also in other animal models.We found that narrow band correlates and broad band anticorrelates with visual contrast in two complementary contrast ranges (low and high respectively). Moreover, BB displayed an earlier response than NB. A thalamocortical spiking neuron network model reproduced the aforementioned results, suggesting they might be due to the presence of two complementary but distinct components of the thalamic input into visual cortical circuitry.

scholarly journals Двумерные брэгговские резонаторы на основе планарных диэлектрических волноводов (от теории к модельному тестированию)

2019 ◽  
Vol 53 (10) ◽  
pp. 1315
Author(s):  
Н.С. Гинзбург ◽  
Н.Ю. Песков ◽  
В.Ю. Заславский ◽  
Е.Р. Кочаровская ◽  
А.М. Малкин ◽  
...  
Keyword(s):  
Narrow Band ◽  
Bragg Reflection ◽  
Dielectric Waveguides ◽  
Wavelength Band ◽  
Reflection Band ◽  
Millimeter Wavelength ◽  
Bragg Structures ◽  
Significant Interest ◽  
Simulation Results ◽  
Analytical Approaches

Using analytical approaches and CST Microwave Studio 3D simulations, we have undertaken a theoretical analysis of electrodynamical characteristics of 2D Bragg structures based on planar oversized dielectric waveguides with double-periodical corrugation. Such structures are of significant interest for obtaining directed narrow-band radiation in heterolasers with large dimensions of an active area. Modeling electrodynamical experiments on 'cold' testing of such structures in millimeter wavelength band were conducted. Fine agreement between the experimental results and the simulation results was demonstrated which includes the presence of the highest-quality mode inside the Bragg reflection band in absence of the periodicity defects.

scholarly journals Preface to the December 2015 issue

2015 ◽  
Author(s):  
Héctor Cancela
Keyword(s):  
Distributed Computing ◽  
Computer Science ◽  
Optical Networks ◽  
Mobile Devices ◽  
Wdm Networks ◽  
Domain Name ◽  
Historical Climate ◽  
Quality Of Protection ◽  
Security Models

We are glad to present the last issue of 2015, completing Volume 18 of the CLEI Electronic Journal. This issue is comprised by the following regular papers.The first paper, “Quality of Protection on WDM networks: A Recovery Probability based approach”, by M. D. Rodas-Brítez and D. P. Pinto-Roa, features a proposal of a new quality of protection (QoP) paradigm for Wavelength Division Multiplexing optical networks. The new approach is flexible, allowing the network administrator to define and select a set of protection levels, based on recovery probabilities which measure the degree of conflict among primary lightpaths sharing backup lightpaths. To show the interest of the approach, a Genetic Algorithm is used to design a routing strategy by multi-objectiveoptimization, minimizing the number of blocked requests, the number of services without protection, the total differences between the requested QoP and the assigned QoP, and the network cost.The second paper, “Towards Scalability for Federated Identity Systems for Cloud-Based Environments”, by A.A. Pereira, J. B. M. Sobral and C. M. Westphall, addresses scalability issues in identity management for cloud computing environments. The authors propose an adapted sticky-session mechanism, as an alternative approach to the more common distributed memory approach, and discuss the implications in therms of computational resources, throughput and overall efficiency. The following work, “Formal Analysis of Security Models for Mobile Devices, Virtualization Platforms, and Domain Name Systems”, by G. Betarte and C. Luna,tackles security models for security-critical applications in three areas: mobile devices, virtualization platforms, and domain name systems. The authors develop formalizations using the Calculus of Inductive Constructions, to study different usual variants of security models in these platforms and their properties.The last paper of this issue is “Digi-Clima Grid: image processing and distributed computing for recovering historical climate data”, by authors S. Nesmachnow, G. Usera and F. Brasileiro. This paper reports an experience of implementing semi-automatic techniques for digitalizing and recovering historical climate records applying parallel computing techniques over distributed computing infrastructures, which was applied to Uruguayan historical climate data.As we complete now the eighteenth year of continued existence of CLEIej, we thank the regional community for its continued support, and we encourage researchers working in computer science and its applications to consider submitting their work to CLEIej, as the the leading electronic, open access journal in Computer Science in Latin America.

Argon Matrix Infrared Spectroscopic Evidence for the Generation of Pentatetraenone by Flash Pyrolysis of Suitable Precursors

1988 ◽  
Vol 41 (2) ◽  
pp. 225 ◽  
Author(s):  
RFC Brown ◽  
KJ Coulston ◽  
FW Eastwood ◽  
MJ Irvine ◽  
ADE Pullin
Keyword(s):  
Carbon Atom ◽  
Infrared Spectra ◽  
Spectral Region ◽  
Narrow Band ◽  
Broad Band ◽  
Carbonyl Carbon Atom ◽  
Carbonyl Carbon ◽  
Argon Matrix ◽  
Spectroscopic Evidence ◽  
Argon Mixture

Five compounds were investigated as precursors for the pyrolytic generation of pentatetraenone, H2C=C=C=C=C=O. These were (1)-(4): 3- ethenylidenebicyclo [2.2.1]hept-5-ene with the following 2,2 substituents : H, COOCOCF3 (1); H, 13COOCOCF3 (1′); (COOCOCF3)2 (2); (COO)2C(CH3)(OCH3) (3); (COO)2Si(CH3)2 (4) and 5-(3′- methylenebicyclo [2.2.1]hept-5′-en-2′-ylidene)-2,2-dimethyl-1,3-dioxan-4,6-dione (5). The five precursors were pyrolysed in a stream of argon at temperatures in the range 350-725°C and the pyrolysate -argon mixture condensed on a CsI plate at c. 10 K. Infrared spectra were obtained between 4000 and 250 cm-1. All five precursors gave two strong bands in the spectral region 2070-2250 cm-1, possibly attributable to pentatetraenone. At lower pyrolytic temperatures the more intense of the two bands was a broad band centred at c. 2128 cm-1 [precursors (1)- (4)] or at c. 2094 cm-1 [precursor (5)]. At higher pyrolytic temperatures these bands were diminished in intensity and replaced by a narrow band at 2207 cm-1 for all five precursors. Bands due to the expected other products for each pyrolysis reaction to form pentatetraenone were observed. H2C413CO ( pentatetraenone substituted by 13C at the carbonyl carbon atom) was prepared by pyrolysis of precursor (1′). We assign the broad bands at c. 2128 cm-1 [precursors (1)-(4)] and at c. 2094 [precursor (5)] to incompletely pyrolysed precursor in which cyclopentadiene has been retained but decomposition in the rest of the molecule has resulted in formation of a =C=C=O group. Bands at 2207, 2068 and 1726 cm-1 we assign to v2-v4 of pentatetraenone. Corresponding bands at 2168, 2056 and 1720 cm-1 are observed in the spectrum of H2C413CO.

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