Search results for "Erasure"

showing 10 items of 11 documents

Rateless codes mitigation technique in a turbulent indoor Free Space Optics link

2014

Free Space Optics (FSO) links are affected by several impairments and, among them, optical turbulence is the most important factor that can degrade the link quality. Due to the presence of this phenomenon, the signal irradiance detected by the receiver fluctuates, thus causing erasure errors and fading events. In this work, we present an indoor Free Space Optics link, in which several turbulence conditions are generated by using two heating elements. We show that the generated turbulence causes erasure errors and packet losses during the data transmission, and we also compare the statistical distribution of the samples with the theoretical models. Moreover, we demonstrate how the applicatio…

PhysicsNetwork packetSettore ING-INF/03 - TelecomunicazioniEncoding (memory)Electronic engineeringBit error rateErasureFadingSettore ING-INF/01 - ElettronicaDecoding methodsFree Space Optics (FSO) optical turbulence rateless codes RaptorQFree-space optical communicationData transmission
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Legal Exclusionism: Legal Personhood Between the Erasure and the Rule of Law

La personalità giuridica è uno status giuridico che conferisce agli esseri umani (e ad alcune entità non-umane) la capacità di partecipare – in modo attivo e passivo – alla generalità delle relazioni giuridiche e la capacità di eseguire atti giuridici. Si tratta di uno status giuridico fondamentale, costitutivo del concetto stesso di diritto. Inoltre, si tratta di uno status limite, ovvero di uno status che distingue i soggetti del diritto dagli oggetti del diritto. Oggi la personalità giuridica è intesa come uno status quasi-naturale, attribuito ad ogni essere umano in maniera incondizionata e inalienabile. Oggi, inoltre, la privazione totale della personalità giuridica, come nel caso dell…

Settore IUS/20 - Filosofia Del DirittoLegal ExclusionismErasurepersonalità giuridicaLegal statuRule of LawEsclusionismo giuridicoLegal personhoodCancellazionestatus giuridicoLegal Exclusionism; Legal status; Legal personhood; Rule of Law; ErasureEsclusionismo giuridico; status giuridico; personalità giuridica; Rule of Law; Cancellazione
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I marginalia di Dino Buzzati: schemi, illustrazioni e disegni

2022

Secondo questa proposta di lettura dell'opera grafica di Dino Buzzati, che può essere estesa anche ad altri autori dal doppio talento, i disegni ai margini della scrittura possono essere interpretati allora nella loro funzione di relazione tra le arti che si risolve in una interazione, una negoziazione, uno slittamento oppure un conflitto, una cancellatura. Inoltre le annotazioni ai margini della scrittura, soprattutto nelle loro versioni grafiche, costituiscono una forma di introspezione autobiografica assai preziosa per ricostruire il profilo del loro autore, se scrittore e disegnatore al contempo.

Settore L-FIL-LET/14 - Critica Letteraria E Letterature ComparateAccording to this proposed analysis of Dino Buzzati's graphic work which can also be extended to other doubly talented authors the drawings at the margins of writing can be interpreted then in their function as a relationship between the arts that results in an interaction a negotiation a slippage or a conflict an erasure. Moreover annotations in the margins of writing especially in their graphic versions constitute a form of autobiographical introspection that is very valuable for reconstructing the profile of their author if writer and artist at the same time.
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From Erasure to Recognition (and Back Again?)

2015

CommunicationFlemish Sign LanguageManually coded languagebusiness.industrylanguageSociolinguistics of sign languagesErasureSign languagePsychologybusinesslanguage.human_languageLinguistics
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Error mitigation using RaptorQ codes in an experimental indoor free space optical link under the influence of turbulence

2015

In free space optical (FSO) communications, several factors can strongly affect the link quality. Among them, one of the most important impairments that can degrade the FSO link quality and its reliability even under the clear sky conditions consists of optical turbulence. In this work, the authors investigate the generation of both weak and moderate turbulence regimes in an indoor environment to assess the FSO link quality. In particular, they show that, due to the presence of the turbulence, the link experiences both erasure errors and packet losses during transmission, and also compare the experimental statistical distribution of samples with the predicted Gamma Gamma model. Furthermore,…

Computer scienceOptical linkReliability (computer networking)Optical linksTelecommunication network reliabilityRytov variance valueSettore ING-INF/01 - ElettronicaTelecomunicacióRaptorQ codesRedundancy (information theory)Indoor free space optical linkFSO communicationsStatisticsTEORIA DE LA SEÑAL Y COMUNICACIONESRedundancy (engineering)Gamma Gamma modelrateless codeElectrical and Electronic Engineeringpacket error rate (PER)Error-free transmissionNetwork packetbusiness.industrySettore ING-INF/03 - TelecomunicazioniSettore ING-INF/02 - Campi ElettromagneticiÒpticaComputer Science ApplicationsTransmission (telecommunications)Bit error rateErasureProbability distributionFree Space Optical (FSO) communicationTelecommunicationsbusinessOptical turbulenceFSO link reliabilityindoor linkError mitigation
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Rateless Codes Performance Analysis in Correlated Channel Model for GEO Free Space Optics Downlinks

2012

Settore ING-INF/03 - TelecomunicazioniFree Space Optics (FSO) technologies for satellite communications offer several advantages: wide bandwidth high rate capability immunity to electromagnetic interference and small equipment size. Thus they are suitable for inter-satellite links deep space communications and also for high data rate ground-to-satellite/satellite-to-ground communications. Nevertheless FSO links suffer impairments that cause power signal degradation at the receiver. Scattering and absorption cause power signal attenuations predictable by suitable deterministic models. Optical turbulence causes random irradiance fluctuations which can generate signal fading events and can thereby only be predicted by statistical models. Attenuation and fading events can corrupt FSO links and so it would be recommended to add mitigation error codes on the communication link. FSO channel can be described as an erasure channel: fading events can cause erasure errors. We have identified in rateless codes (RCs) a suitable solution to be employed in FSO links. RCs do not need feedback and they add a redundant coding on the source data that allows the receiver to recover the whole payload despite erasure errors. We implemented two different of rateless codes: Luby Transform (LT) and Raptor. We analyzed their performances on a simulated turbulent GEO FSO downlink (1 Gbps - OOK modulation) at a 106 μm wavelength and for different values of zenith angles. Assuming a plane-wave propagation and employing Hufnagel-Valley we modeled the downlink using: 1) a temporal correlated channel model based on Gamma-Gamma probability distribution and 2) an irradiance covariance function that we converted on a time function using Taylor frozen eddies hypothesis. Our new channel model is able to simulate irradiance fluctuations at different turbulence conditions as it will be shown in the full paper. We will also report performance results of LT and Raptor codes at overhead range varying between 0 and 50% and for different values of source packets.Settore ING-INF/01 - Elettronica
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Diagonal space time hadamard codes with erasure decoding algorithm

2005

A major challenge in the area of space time (ST) codes is to find codes suitable for efficient decoding, thus overcoming the problem of many existing ST code designs which require maximum-likelihood (ML) decoding. A solution could be to apply single-input single-output (SISO) channel codes and theory over temporal channel fading to the multi-input single-output (MISO) code construction and classical suboptimum decoding methods. For these purposes, an ST code construction which allows the use of efficient decoding algorithms is described. We propose a concatenated code, where the inner code is the diagonal ST Hadamard (D-STH) code with Paley constructions and the outer code is an algebraic b…

Prefix codeBlock codePolynomial codeComputer scienceConcatenationList decodingData_CODINGANDINFORMATIONTHEORYSequential decodingLocally testable codeSystematic codeReed–Solomon error correctionHadamard transformCyclic codeFadingLow-density parity-check codeComputer Science::Information TheorySelf-synchronizing codeHadamard codeConcatenated error correction codeReed–Muller codeSerial concatenated convolutional codesAntenna diversityLinear codeConvolutional codeErasureConstant-weight codeErasure codeAlgorithmDecoding methodsCommunication channelIEEE Wireless Communications and Networking Conference, 2005
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Control and steering of phase domain walls

2009

We show experimentally the feasibility of optically controlled location, individual addressing/erasure and steering of phase domain walls by injection of coherent addressing pulses into a phase-locked four-wave-mixing photorefractive oscillator.

Physicsbusiness.industryPhysics::OpticsPhase domainPhotorefractive effectAtomic and Molecular Physics and OpticsLight intensityOpticsFresnel numberErasureSpatial frequencybusinessLaser beamsLaser lightOptics Express
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Quantum erasure within the optical Stern-Gerlach model

2005

In the optical Stern-Gerlach effect the two branches in which the incoming atomic packet splits up can display interference pattern outside the cavity when a field measurement is made which erases the which-way information on the quantum paths the system can follow. On the contrary, the mere possibility to acquire this information causes a decoherence effect which cancels out the interference pattern. A phase space analysis is also carried out to investigate on the negativity of the Wigner function and on the connection between its covariance matrix and the distinguishability of the quantum paths.

PhysicsQuantum PhysicsQuantum decoherenceStern–Gerlach experimentField (physics)FOS: Physical sciencesInterference (wave propagation)Atomic and Molecular Physics and OpticsClassical mechanicsDEFLECTIONPhase spaceQuantum mechanicsErasureWigner distribution functionQuantum Physics (quant-ph)QuantumPhysical Review A
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2017

Fast and reliable reset of a qubit is a key prerequisite for any quantum technology. For real world open quantum systems undergoing non-Markovian dynamics, reset implies not only purification, but in particular erasure of initial correlations between qubit and environment. Here, we derive optimal reset protocols using a combination of geometric and numerical control theory. For factorizing initial states, we find a lower limit for the entropy reduction of the qubit as well as a speed limit. The time-optimal solution is determined by the maximum coupling strength. Initial correlations, remarkably, allow for faster reset and smaller errors. Entanglement is not necessary.

PhysicsGeneral Physics and AstronomyQuantum PhysicsQuantum entanglement01 natural sciences010305 fluids & plasmasQuantum technologyQubit0103 physical sciencesKey (cryptography)Numerical controlErasureStatistical physics010306 general physicsReset (computing)QuantumNew Journal of Physics
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