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See detailDetection of pilot contamination attack using random training and massive MIMO
Kapetanovic, D.; Zheng, Gan UL; Wong et al

in Personal Indoor and Mobile Radio Communications (PIMRC), 2013 IEEE 24th International Symposium on (2013)

Channel estimation attacks can degrade the performance of the legitimate system and facilitate eavesdropping. It is known that pilot contamination can alter the legitimate transmit precoder design and ... [more ▼]

Channel estimation attacks can degrade the performance of the legitimate system and facilitate eavesdropping. It is known that pilot contamination can alter the legitimate transmit precoder design and strengthen the quality of the received signal at the eavesdropper, without being detected. In this paper, we devise a technique which employs random pilots chosen from a known set of phase-shift keying (PSK) symbols to detect pilot contamination. The scheme only requires two training periods without any prior channel knowledge. Our analysis demonstrates that using the proposed technique in a massive MIMO system, the detection probability of pilot contamination attacks can be made arbitrarily close to 1. Simulation results reveal that the proposed technique can significantly increase the detection probability and is robust to noise power as well as the eavesdropper's power. [less ▲]

Detailed reference viewed: 176 (0 UL)
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See detailDetection of Population Mobility Anomalies in Senegal from Base Station Profiles
Melakessou, Foued UL; Derrmann, Thierry UL; Frank, Raphaël UL et al

Scientific Conference (2015, April 08)

The analysis of Call Detail Records has captured the attention of traffic and transportation researchers to optimize people's mobility. In our work, we would like to analyze Call Detail Records in order ... [more ▼]

The analysis of Call Detail Records has captured the attention of traffic and transportation researchers to optimize people's mobility. In our work, we would like to analyze Call Detail Records in order to extract realistic human mobility models adapted to the Senegal use case. In this paper, we describe our analysis of the available D4D datasets. The first contribution is the modeling of the daily traffic demand profile of each antenna, by considering voice and short message services. The evaluation of mobility models will help to better design and develop future infrastructures in order to better support the actual demand. A classification has been performed into urban, suburban and rural modes. An algorithm has been developed to detect traffic anomalies in 2013, based on the daily profiles. The second contribution corresponds to the generation of inter-antennas and inter-arrondissements mobility graphs for each month of 2013. [less ▲]

Detailed reference viewed: 161 (5 UL)
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See detailDetection of qubit-oscillator entanglement in nanoelectromechanical systems
Schmidt, Thomas UL; Borkje; Bruder, Christoph et al

in Physical Review Letters (2010), 104

Experiments over the past years have demonstrated that it is possible to bring nanomechanical resonators and superconducting qubits close to the quantum regime and to measure their properties with an ... [more ▼]

Experiments over the past years have demonstrated that it is possible to bring nanomechanical resonators and superconducting qubits close to the quantum regime and to measure their properties with an accuracy close to the Heisenberg uncertainty limit. Therefore, it is just a question of time before we will routinely see true quantum effects in nanomechanical systems. One of the hallmarks of quantum mechanics is the existence of entangled states. We propose a realistic scenario making it possible to detect entanglement of a mechanical resonator and a qubit in a nanoelectromechanical setup. The detection scheme is all done by standard current and noise measurements of an atomic point contact coupled to an oscillator and a qubit. This setup could allow for the first observation of entanglement between a continuous and a discrete quantum system in the solid state. [less ▲]

Detailed reference viewed: 96 (1 UL)
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See detailDetection of Sentiment in Luxembourgish User Comments
Gierschek, Daniela UL

Doctoral thesis (2022)

Sentiment is all around us in everyday life. It can be found in blog posts, social media comments, text messages and many other places where people express themselves. Sentiment analysis is the task of ... [more ▼]

Sentiment is all around us in everyday life. It can be found in blog posts, social media comments, text messages and many other places where people express themselves. Sentiment analysis is the task of automatically detecting those sentiments, attitudes or opinions in written text. In this research, the first sentiment analysis solution for the low-resource language, Luxembourgish, is conducted using a large corpus of user comments published on the RTL Luxembourg website www.rtl.lu. Various resources were created for this purpose to set the foundation for further sentiment research in Luxembourgish. A Luxembourgish sentiment lexicon and an annotation tool were built as external resources that can be used for collecting and enlarging training data for sentiment analysis tasks. Additionally, a corpus of mainly sentences of user comments was annotated with negative, neutral and positive labels. This corpus was furthermore automatically translated to English and German. Afterwards, diverse text representations such as word2vec, tf-idf and one-hot encoding were used on the three versions of the corpus of labeled sentences for training different machine learning models. Furthermore, one part of the experimental setup leveraged linguistic features for the classification process in order to study their impact on sentiment expressions. By following such a broad strategy, this thesis not only sets the basis for sentiment analysis with Luxembourgish texts but also intends to give recommendations for conducting sentiment detection research for other low-resource languages. It is demonstrated that creating new resources for a low-resource language is an intensive task and should be carefully planned in order to outperform working with translations where the target language is a high-resource language such as English and German. [less ▲]

Detailed reference viewed: 97 (15 UL)
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See detailDetection of sparse random signals using compressive measurements
Shankar, Bhavani UL; Chatterjee, Saikat; Ottersten, Björn UL

in Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference on (2012)

We consider the problem of detecting a sparse random signal from the compressive measurements without reconstructing the signal. Using a subspace model for the sparse signal where the signal parameters ... [more ▼]

We consider the problem of detecting a sparse random signal from the compressive measurements without reconstructing the signal. Using a subspace model for the sparse signal where the signal parameters are drawn according to Gaussian law, we obtain the detector based on Neyman-Pearson criterion and analytically determine its operating characteristics when the signal covariance is known. These results are extended to situations where the covariance cannot be estimated. The results can be used to determine the number of measurements needed for a particular detector performance and also illustrate the presence of an optimal support for a given number of measurements. [less ▲]

Detailed reference viewed: 166 (5 UL)
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See detailDetection of Spoofing Attacks in Aeronautical Ad-Hoc Networks Using Deep Autoencoders
Hoang, Tiep M.; Van Chien, Trinh; Van Luong, Thien et al

in IEEE Transactions on Information Forensics and Security (2022), 17

We consider an aeronautical ad-hoc network relying on aeroplanes operating in the presence of a spoofer. The aggregated signal received by the terrestrial base station is considered as “clean” or “normal” ... [more ▼]

We consider an aeronautical ad-hoc network relying on aeroplanes operating in the presence of a spoofer. The aggregated signal received by the terrestrial base station is considered as “clean” or “normal”, if the legitimate aeroplanes transmit their signals and there is no spoofing attack. By contrast, the received signal is considered as “spurious” or “abnormal” in the face of a spoofing signal. An autoencoder (AE) is trained to learn the characteristics/features from a training dataset, which contains only normal samples associated with no spoofing attacks. The AE takes original samples as its input samples and reconstructs them at its output. Based on the trained AE, we define the detection thresholds of our spoofing discovery algorithm. To be more specific, contrasting the output of the AE against its input will provide us with a measure of geometric waveform similarity/dissimilarity in terms of the peaks of curves. To quantify the similarity between unknown testing samples and the given training samples (including normal samples), we first propose a so-called deviation-based algorithm . Furthermore, we estimate the angle of arrival (AoA) from each legitimate aeroplane and propose a so-called AoA-based algorithm . Then based on a sophisticated amalgamation of these two algorithms, we form our final detection algorithm for distinguishing the spurious abnormal samples from normal samples under a strict testing condition. In conclusion, our numerical results show that the AE improves the trade-off between the correct spoofing detection rate and the false alarm rate as long as the detection thresholds are carefully selected. [less ▲]

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See detailDetection of Temporally Correlated Primary User Signal with Multiple Antennas
Hashemi, Hadi; Mohammadi Fard, Sina; Taherpour, Abbas et al

in International Conference on Cognitive Radio Oriented Wireless Networks (CROWNCOM) (2015)

In this paper, we address the problem of multiple antenna spectrum sensing in cognitive radios (CRs) when the samples of the primary user (PU) signal as well as samples of noise are assumed to be ... [more ▼]

In this paper, we address the problem of multiple antenna spectrum sensing in cognitive radios (CRs) when the samples of the primary user (PU) signal as well as samples of noise are assumed to be temporally correlated. We model and formulate this multiple antenna spectrum sensing problem as a hypothesis testing problem. First, we derive the optimum Neyman-Pearson (NP) detector for the scenario in which the channel gains, the PU signal and noise correlation matrices are assumed to be known. Then, we derive the sub-optimum generalized likelihood ratio test (GLRT)-based detector for the case when the channel gains and aforementioned matrices are assumed to be unknown. Approximate analytical expressions for the false-alarm probabilities of the proposed detectors are given. Simulation results show that the proposed detectors outperform some recently-purposed algorithms for multiple antenna spectrum sensing. [less ▲]

Detailed reference viewed: 44 (0 UL)
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See detailDetection of vulnerabilities in the international protection procedure
Petry, Ralph UL; Osburg, Mathis UL; Nienaber, Birte UL

Article for general public (2021)

The vulnerability of applicants for international protection is a key component of the EU acquis on asylum, with both the Recast Asylum Procedures Directive (2013/32/EU) and the Recast Reception ... [more ▼]

The vulnerability of applicants for international protection is a key component of the EU acquis on asylum, with both the Recast Asylum Procedures Directive (2013/32/EU) and the Recast Reception Conditions Directive (2013/33/EU) providing special provisions for vulnerable persons with regard to the procedure for international protection (i.e. special procedural guarantees) and reception (i.e. special reception needs), respectively. Hence, in order for Member States to be able to provide and guarantee these special provisions for vulnerable applicants, it is essential that a potential vulnerability is detected and identified at an early stage in the international protection procedure. It is in this context that EMN Luxembourg decided, in consultation with the Luxembourgish authorities and national stakeholders, to launch a request for information to Member States via the EMN ad-hoc query system. As a consequence, the aim of this Inform is to map how vulnerabilities of applicants for international protection are detected in the international protection procedure in EU Member States and how the follow-up of this detection is guaranteed by the authorities and stakeholders involved, including special procedural guarantees. [less ▲]

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See detailDetention and alternatives to detention in international protection and return procedures in Luxembourg
Sommarribas, Adolfo UL; Petry, Ralph UL; Nienaber, Birte UL

Report (2021)

The main objective of this study of the European Migration Network is to provide objective and reliable information about the usage of detention and alternatives to detention in international protection ... [more ▼]

The main objective of this study of the European Migration Network is to provide objective and reliable information about the usage of detention and alternatives to detention in international protection and return procedures in Luxembourg. Luxembourgish legislation, namely the amended Law of 29 August 2008 on Free Movement of Persons and Immigration (Immigration Law) and the Law of 18 December 2015 on International Protection and Temporary Protection (Asylum Law), foresees three alternatives to detention: - Alternative 1: Reporting obligations, which includes the obligation to surrender a passport, travel document or identity document; - Alternative 2: Home custody (+ electronic monitoring, if necessary); - Alternative 3: Deposition of a financial guarantee of 5.000€. In principle, the assessment between detention or alternatives to detention is made at the same time as when the grounds for detention are considered, as long as the Directorate of Immigration, as the responsible authority, has all the necessary information to decide if an alternative to detention can be ordered. Furthermore, the possibility to impose an alternative to detention is in principle systemically considered, as both relevant laws foresee that the detention decision is ordered in writing by the Minister on the basis of a case-by-case assessment, where necessary and if other less coercive measures cannot be effectively applied. Grounds for detention are generally rejected in favour of an alternative to detention if the person concerned falls within the category of vulnerable groups and if person is able to proof effective guarantees of representation to prevent the risk of absconding. This latter obligation on the third-country national to revert the legal presumption that there is a risk of absconding remains the main challenge because effective guarantees of representation are not defined by law. This is particularly challenging in the context of return procedures, where this legal presumption exists in nearly all cases where a third-country national has no valid identity, travel or residence documents. In the absence of such effective guarantees of representation, the Minister in charge of Immigration and Asylum generally does not make the decision to apply an alternative to detention. Consequently, the research in the context of this study has shown that alternatives to detention are only rarely used in Luxembourg, with the important exception of home custody in the Emergency Housing Structure of Kirchberg (‘Structure d’hébergement d’urgence Kirchberg’ – SHUK). The SHUK serves as a semi-open return facility for applicants for international protection and irregularly staying third-country nationals whose fingerprints have already been registered in Eurodac by another Member State and are therefore likely to be transferred to that Member State, in accordance with the Dublin III Regulation. A placement at the SHUK corresponds to home custody. The rare use of alternatives to detention also results in the fact that there is generally not much data available in this regard, with the important exception of home custody in the SHUK, which is more widely used. [less ▲]

Detailed reference viewed: 72 (11 UL)
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See detailThe Detention of Al-Qaeda Suspects at Guantanamo Bay: United Kingdom Perspectives
Happold, Matthew UL

in Human Rights Law Review (2004), 4

Detailed reference viewed: 210 (1 UL)
See detailLa détention systématique des personnes secourues en mer et transférées à Malte: comment l'immigration devient une ressource
Lemaire, Léa UL

in Fouchard, Isabelle; Larralde, Jean-Manuel; Lévy, Benjamin (Eds.) et al Les sens de la privation de liberté (2019)

Detailed reference viewed: 134 (2 UL)
See detailLa detenzione "amministrativa" dello straniero.
Marletta, Angelo UL

in Antigone. Bimestrale di critica dell'emergenza. (2012), (3), 110-123

Detailed reference viewed: 72 (7 UL)
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See detailLa detenzione “amministrativa” dello straniero e la riserva di giurisdizione in materia di libertà personale.
Marletta, Angelo UL

in Criminalia. Annuario di Scienze Penalistiche (2012)

Detailed reference viewed: 128 (17 UL)
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See detailDeterioration of Basic Properties of the Materials in FRP-Strengthening RC Structures under Ultraviolet Exposure
Zhao, Jun; Cai, Gaochuang UL; Cui, Lu et al

in Polymers (2017)

This paper presents an experimental study of the basic properties of the main materials found in reinforced concrete (RC) structures strengthened by fibre reinforced polymer (FRP) sheets with scope to ... [more ▼]

This paper presents an experimental study of the basic properties of the main materials found in reinforced concrete (RC) structures strengthened by fibre reinforced polymer (FRP) sheets with scope to investigate the effect of ultraviolet (UV) exposure on the degradation of FRP, resin adhesive materials and concrete. The comparison studies focused on the physical change and mechanical properties of FRP sheet, and resin adhesive materials and concrete before and after UV exposure. However, the degradation mechanisms of the materials under UV exposure were not analyzed. The results show that the ultimate tensile strength and modulus of FRP sheets decrease with UV exposure time and the main degradation of FRP-strengthened RC structures is dependent on the degradation of resin adhesive materials. The increase in the number of FRP layers cannot help to reduce the effect of UV exposure on the performance of these materials. However, it was verified that carbon FRP materials have a relatively stable strength and elastic modulus, and the improvement of the compression strength of concrete was also observed after UV exposure. [less ▲]

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See detailDeterminant representation of the domain-wall boundary condition partition function of a Richardson–Gaudin model containing one arbitrary spin
Faribault, Alexandre; Tschirhart, Hugo UL; Muller, Nicolas

in Journal of Physics. A, Mathematical and Theoretical (2016)

In this work we present a determinant expression for the domain-wall boundary condition partition function of rational (XXX) Richardson–Gaudin models which, in addition to N-1 spins 1/2, contains one ... [more ▼]

In this work we present a determinant expression for the domain-wall boundary condition partition function of rational (XXX) Richardson–Gaudin models which, in addition to N-1 spins 1/2, contains one arbitrarily large spin S. The proposed determinant representation is written in terms of a set of variables which, from previous work, are known to define eigenstates of the quantum integrable models belonging to this class as solutions to quadratic Bethe equations. Such a determinant can be useful numerically since systems of quadratic equations are much simpler to solve than the usual highly nonlinear Bethe equations. It can therefore offer significant gains in stability and computation speed. [less ▲]

Detailed reference viewed: 101 (1 UL)
See detailDeterminanten des Geschlechterunterschieds im Schulerfolg. Ergebnisse einer quantitativen Studie aus Bern
Lupatsch, Judith; Hadjar, Andreas UL

in Geschlechtsspezifische Bildungsungleichheiten (2011)

Detailed reference viewed: 160 (1 UL)
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See detailDeterminanten von Lehrererwartungen im Grundschulalter.
Baudson, Tanja Gabriele UL; Preckel, F.

Scientific Conference (2010)

Detailed reference viewed: 67 (1 UL)
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See detailDeterminants and Temporal Dynamics of Strategic Divergence: Evidence from Europe
Brauer, Matthias UL; Heitmann, Mark

in Journal of World Business (2013), 48(1), 110-121

Detailed reference viewed: 205 (127 UL)