Topology-based Clusterhead Candidate Selection in Wireless Ad-hoc and Sensor Networks

in Abstract book of 2nd IEEE/ACM International Workshop on Software for Sensor Networks (SensorWare 2007) (2007)

Support in case of sickness and disability. The perspectives of the elderly

in Abstract book of 10th European Congress of Psychology (2007)

A Game-Theoretic Approach to Normative Multi-Agent Systems

in Normative Multi-agent Systems (2007)

We aim to explain our own approach, and we are therefore very brief with respect to recent related approaches in the area of normative multiagent sys- tems. For these other approaches, see the special ... [more ▼]

We aim to explain our own approach, and we are therefore very brief with respect to recent related approaches in the area of normative multiagent sys- tems. For these other approaches, see the special issue on normative multiagent systems in Computational and Mathematical Organization Theory[68], these DROPS proceedings, the proceedings of the biannual workshops on deontic logic in computer science (¢EON) and of the COIN workshop series. 1The layout of this paper follows the Øve questions above, addressing each of them in a new section. [less ▲]

Utilisation d'un modèle de réponse à l'item pour la validation d'une échelle des attitudes professionnelles des médecins généralistes

in Journal of Educational Measurement and Applied Cognitive Sciences (2007)

Nous avons développé une échelle des attitudes professionnelles des médecins généralistes destinée à évaluer le niveau de communication thérapeutique dispensé durant les consultations. La construction de ... [more ▼]

Nous avons développé une échelle des attitudes professionnelles des médecins généralistes destinée à évaluer le niveau de communication thérapeutique dispensé durant les consultations. La construction de l'échelle a abouti à un questionnaire constitué de 15 items à 10 modalités de réponse allant de "Jamais" à "Toujours". Après avoir étudié les propriétés métriques de l’échelle selon une méthodologie classique, nous avons employé un modèle de réponse à l’item (le Generalized Partial Credit Model, GPCM) pour explorer un éventuel fonctionnement différentiel d’item (FDI) selon le genre des individus. Le modèle a été construit dans un cadre bayésien en utilisant un algorithme MCMC. La détection du FDI est basée sur le test de rapport de vraisemblance, en comparant le modèle de référence où tous les paramètres associés aux items sont communs aux hommes et aux femmes, à un modèle incluant deux ensembles de paramètres distincts selon le genre des individus pour un item particulier. La démarche a été appliquée aux 338 observations de l'échantillon de validation ne comportant pas de données manquantes. Parmi les 15 items de l'échelle, seul l'item 6 ("Mon médecin m’informe sur les effets secondaires des médicaments") présente un FDI significatif au niveau de signification de 5% (p = 0.016). Cet item est plus discriminant chez les hommes. De plus, il semble que, à un niveau de communication thérapeutique égal, les hommes ont une probabilité supérieure aux femmes de répondre aux catégories les plus élevées. Finalement, nous avons décidé de ne pas écarter cet item car 1) le FDI est modéré (si nous ajustons le test pour les comparaisons multiples, celui-ci n'est plus significatif au niveau 5%) et 2) nous n'avons aucune interprétation qualitative de cette différence. [less ▲]

The Roles of Roles in Agent Communication Languages

in Proceedings of the IEEE/WIC/ACM International Conference on Intelligent Agent Technology (IAT'06) (2006)

Directory Services for Mobile Multi-hop Ad hoc Networks- State of the Art and Perspectives

in NPC 2006 - IFIP International Conference on Network and Parallel Computing (2006)

CAA-DRIP: a framework for implementing Coordinated Atomic Actions

in The 17th International Symposium on Software Reliability (2006)

Is there a PPI effect on psychomotor reaction time?

in Journal of Psychophysiology (2006), 21(2), 138-138

Description of bad-signatures for Network Intrusion Detection

in Proceedings of the 4th. Australasian Information Security Workshop (AISW-NetSec 2006) (2006)

Two professional attitudes measurement scales evaluated by patients for general practitioners and dispensing chemists

in Society for Health and Medical Sociology (2006)

To construct and validate a scale of Professional Attitudes for both General Practitioners (in french, Attitudes Professionnelles des Médecins Generalistes) and dispensing chemists (Attitudes ... [more ▼]

To construct and validate a scale of Professional Attitudes for both General Practitioners (in french, Attitudes Professionnelles des Médecins Generalistes) and dispensing chemists (Attitudes Professionnelles des Pharmaciens d’Officine). Methods: Stage 1. The construction and qualitative validation of a scale. By interviewing 40 patients in a preventive-care center in east of France in addition to 21 general practitioners and 22 dispensing chemists, we targeted items which could possibly help us formalize a theoretical construction of professional attitudes which intervened in the instauration and follow-up of patient treatments. Then, with the help of a group of experts, we determined which generic items in the questionnaire could be validated and, finally, identified the functions which fulfilled these attitudes. Stage 2. We statistically validated the APMG and APPO scales and then studied the classic metric characteristics of the scales by using a questionnaire which was auto-administered to 393 patients from East of France. We have completed this validation with a differential item functioning analysis to determine if the questions have similar properties among men and women. Results: 15 relational items in general practitioners and 9 in dispensing chemists were identified. They are associated with information, communication and education. Each scale is one-dimensional. Analysis showed high internal coherence (Cronbach’s alpha coefficient was 0.91 and 0.87 respectively) and acceptable reproducibility (intra-class correlation coefficients were respectively 0.74 and 0.72). Differential item functioning analysis for gender is in progress. Conclusion: The professional attitudes, we isolated represent important criteria in the quality of interpersonal doctor-patient and chemist-patient relationships. The metric characteristics of the two scales were deemed satisfactory. This suggests that they can be used as an aid in training in the healthcare professional-patient relationship, in decision-making and in assessing relational competencies. [less ▲]

Die Struktur der demokratischen Legitimität im französischen Recht : zwischen Monismus und Pluralismus, zwischen Subjekt-Symbolik und Gewaltenmechanik

in Europäische Grundrechte-Zeitschrift (2006), 33

The density of nociceptive nerve fibres in the dura mater lumbalis of rats is enhanced after laminectomy, even after application of autologous fat grafts.

in Europ Spine J (2006), 15(10), 1561-1632

The generation of respiratory rhythms in birds

in Physica A. Statistical Mechanics and its Applications (2006), 371(1), 84-87

The generation of precise respiratory rhythms is vital for birds, which must generate specific pressure patterns to perform several activities, song being one of the most demanding ones. These rhythms ... [more ▼]

The generation of precise respiratory rhythms is vital for birds, which must generate specific pressure patterns to perform several activities, song being one of the most demanding ones. These rhythms emerge as the interaction between a peripheral system and a set of neural nuclei which control the action of expiratory and inspiratory muscles. A computational model was proposed recently to account for this interaction. In this work, we describe the set of solutions that this model can display as its parameters are varied, and compare experimental records of air sac pressure patterns with the predictions of the model. © 2006 Elsevier B.V. All rights reserved. [less ▲]

powerJava: ontologically founded roles in object oriented programming language

in Proceedings of ACM Symposium on Applied Computing (SAC'06), Track Object Oriented Programming Languages and Systems (OOPS'06) (2006)

In this paper we introduce a new view on roles in Object Oriented programming languages, based on an ontological analysis of roles. A role is always associated with an object instance playing the role and ... [more ▼]

In this paper we introduce a new view on roles in Object Oriented programming languages, based on an ontological analysis of roles. A role is always associated with an object instance playing the role and also to an object instance (its institution) which represents its context. The definition of a role depends on the definition of the institution. This property allows to endow role-players with powers that can modify the state of the institution and of the other roles defined in it. As an example, we introduce a role construct in Java, where the abolve features are interpreted as follows. Roles are implemented as classes, which can be instantiated only in presence of an instance of the player and of an instance of an institution. The definition of a class implementing a role is included in the class of the institution, the role belongs to. Powers are methods which can access private fields and methods of the institution they belong to, and of the other roles of the same institution [less ▲]

La mobilité des frontaliers travaillant au Luxembourg

in Dimensions socio-économiques de la mobilité transfrontalière - actes du séminaire transfrontalier EURES-OIE (2006)

L’objet de notre communication est de présenter les premiers résultats de deux études distinctes, actuellement en cours de réalisation, et qui traitent chacune d’un aspect différent de la mobilité. Tout ... [more ▼]

L’objet de notre communication est de présenter les premiers résultats de deux études distinctes, actuellement en cours de réalisation, et qui traitent chacune d’un aspect différent de la mobilité. Tout d’abord, une étude du lieu de travail des frontaliers occupés au Luxembourg. La mobilité y sera abordée par le biais des déplacements domicile-travail. Puis, notre seconde étude s’intéressera à la mobilité résidentielle, c’est-à-dire les changements de lieu de résidence des personnes travaillant au Luxembourg. [less ▲]

Un baromètre de la qualité de vie des étudiant-e-s au sein des universités européennes : une nécessité éthique.

in Analyse des Systèmes de Santé (2006)

Les politiques d’éducation et de formation doivent doter les étudiant-e-s d’aptitudes, de capacités et de compétences nécessaires pour affronter les transformations socioéconomiques (Conseil Européen de ... [more ▼]

Les politiques d’éducation et de formation doivent doter les étudiant-e-s d’aptitudes, de capacités et de compétences nécessaires pour affronter les transformations socioéconomiques (Conseil Européen de Lisbonne 2000). Pour augmenter la compétitivité des ressources humaines, la croissance économique et la cohésion sociale en Europe (Déclaration de Bologne 1999), la question de l'employabilité s'impose progressivement comme une des finalités des enseignements. Dans un contexte de massification des universités, les questions de politique globale suscitent plus d'intérêt que la qualité de vie et les jugements des étudiant-e-s sur leur expérience universitaire. Une attention particulière est cependant accordée dans les recherches à l'analyse des conditions de leur socialisation, de leur intégration dans l'institution (rapports avec les autres étudiant-e-s, avec leurs enseignants, épanouissement personnel, engagement civique...) et de ce qu'ils ont retiré pour leur parcours ultérieur. Des travaux sur l'évaluation de la qualité et de la satisfaction des services rendus aux étudiant-e-s sont également de plus en plus engagés par les établissements d'enseignement supérieurs pour répondre aux exigences des processus d'accréditation. Parallèlement à ces études, la problématique du bien-être des étudiant-e-s reste peu documentée. Or une bonne santé constitue un facteur positif de réussite. La qualité de vie des étudiant-e-s est pourtant une priorité de santé publique pour ces jeunes à qui on demande aujourd'hui de relever un tel défi. Dans l'enceinte de trois universités européennes, nous avons réalisé auprès d'étudiants polonais (Po), roumains (Ro) et français (Fr) de 1ère année en sciences humaines et sociales. Notre objectif est de présenter les principaux résultats de ce travail afin de susciter une discussion éthique sur la place de la qualité de vie et de la santé au sein des universités européennes. La méthode s'est appuyée sur un questionnaire auto-administré, 1602 étudiants (93 français (Fr), 190 roumains (Ro), 480 polonais (Po)) ont répondu. Des mesures sur les consommations de psychotopes, tabac, alccol, drogues, tc. ont été réalisées. La santé psychique a été évaluée à l'aide d'échelles validées (Brief Cope, Estime de soi, Général Health Qquestionnaire, etc.). Les principaux résultats. L'âge moyen est de 20 ans. Globalement, les Ro se sentent en moins bonne santé que les Fr et les Po alors qu'ils jouissent de la meilleure estime de soi. Ils sont les plus nombreux à consulter leur médecin et à vouloir rencontrer un psychiatre. Les Fr et les Po sont les plus nombreux à avoir mal au dos, mal à la tête, à se dire fatigués et à déclarer consommer des tranquillisants. Les Po consomment davantage de stimulants et de somnifères. Les Fr sont les plus nombreux à boire de l'alcool et à prendre des amphétamines et de l'ecstasy. Depuis la rentrée universitaire, les Po sont les plus nombreux à avoir modifié leur prise de drogues, et comme les Ro, ils ont augmenté leur consommation de tabac. Pour faire face à leurs problèmes, les Fr dédramatisent les situations grâce à l'humour et aux distractions, les Po recherchent un soutien social et affectif, les Ro libèrent leurs sentiments par la parole et positivent le sens qu’ils donnent aux événements. Durant les derniers mois, les Ro sont les plus nombreux à avoir entamé une action contre le stress. Discussion. L'entrée à l'universitaire exerce une influence sur l'équilibre psychique des étudiants. Les comportements à l’égard de leur qualité de vie et de leur santé méritent d’être observés, leur compréhension est une nécessité éthique: - D'abord, parce qu'il est vraisemblablement peu efficace d’agir sur ces comportements sans agir sur leurs causes. On sait aujourd’hui que des comportements considérés comme nocifs (alcool, tabac, drogues) sont produits en réponse à des carences ou à des agressions de l’environnement pour faire face à la souffrance psychique, à l’isolement, au manque de perspectives. Ce que l'on nomme "problèmes" sont plutôt « des comportements de survie ou des appels au secours » dans le contexte où ils s’expriment. - Ensuite parce qu'il paraît peu acceptable de considérer les étudiant-e-s comme responsables de ce qui leur est imposé : stress, solitude, manque de respect des droits de l’étudiant, … L'équité d'accès à la formation et à l’éducation nécessite de repenser la santé au sein des universités comme partie intégrante d’un dispositif d’accompagnement des etudiants-e-s dans leur réussite universitaire. Perspectives. Un « Baromètre européen de la qualité de vie des étudiant-e-s » permettrait d’analyser l’apparition et l’adoption des comportements bénéfiques ou délétères à l'égard de la santé et du bien-être. Ce type de recherche saisirait à la fois les représentations des jeunes et l’intrication intime, qui prédomine à l’adolescence, ente les problèmes à dominante physique et les problèmes à dominante affective ou relationnelle. Cette connaissance constituerait un support pour des programmes de prévention et de promotion de la santé qui mériterait d'être mené aussi bien du côté des étudiant-e-s que du côté des professionnels de la santé et des enseignants. [less ▲]

Preference reasoning for argumentation: non-monotonicity and algorithms

in Proceedings of the NMR'06 (2006)

Strengthening Admissible Coalitions

in Proceedings of the 17th European Conference on Artificial Intelligence (ECAI'06) (2006)

Merging Optimistic and Pessimistic Preferences

in Proceedings of FUSION 2006 (2006)

In this paper we consider the extension of non-monotonic preference logic with the distinction between controllable(or endogenous) and uncontrollable(or exogenous)variables, which can be used for example ... [more ▼]

In this paper we consider the extension of non-monotonic preference logic with the distinction between controllable(or endogenous) and uncontrollable(or exogenous)variables, which can be used for example in agent decision making and deliberation. We assume that the agent is optimistic about its owncontrollables and pessimistic about its uncontrollables, and we study ways to merge these two distinct dimensions.We also consider complex preferences, such as optimistic preferences conditional on an uncontrollable, or optimistic preferences conditional on a pessimistic preference. [less ▲]

Partnerverlust im Alter: Zwischen Bewältigungsverhalten und Lebenszufriedenheit

in Abstract book of 45. Kongress der Deutschen Gesellschaft für Psychologie (2006)

Technology related issues regarding fabrication of AlGaN/GaN-based MOSHFETs with GdScO3 as dielectric,

in Proceedings of 6th Intern. Conf. Advanced Semicon. Dev. & Microsystems ASDAM’06 (2006)

Starting out from our well established process for AlGaN/GaN HFETs we discuss ways to enrich the process in order to fabricate Metal-Oxide-Semiconductor HFETs (MOSHFETs) with a Gadolinium Scandate (GdScO3 ... [more ▼]

Starting out from our well established process for AlGaN/GaN HFETs we discuss ways to enrich the process in order to fabricate Metal-Oxide-Semiconductor HFETs (MOSHFETs) with a Gadolinium Scandate (GdScO3) insulation layer. In particular, adequate processing orders, various etching procedures and possible drawbacks of the GdScO3 deposition process on ohmic contacts are discussed. Making use of the gained knowledge we fabricated GdScO3-MOSHFETs for the first time. Compared to a conventional HFET the new device shows a higher saturation drain current and a lower gate leakage current. Nevertheless, the potential insulating properties of GdScO3 are not fully exploited yet and further optimization of the deposition process is needed. [less ▲]

Count-As Conditionals, Classification and Context

in Proceedings of the 17th European Conference on Artificial Intelligence (ECAI'06) (2006)

The Fault-Tolerant Insulin Pump Therapy

in Proceedings of the Workshop on Rigorous Engineering of Fault-Tolerant Systems (2005, July)

In this paper we describe our experience using Coordinated Atomic Actions (CAAs) to design a control system for a medical treatment, which has high reliability requirements. The “Fault-Tolerant Insulin ... [more ▼]

In this paper we describe our experience using Coordinated Atomic Actions (CAAs) to design a control system for a medical treatment, which has high reliability requirements. The “Fault-Tolerant Insulin Pump Therapy” is based on the Continuous Subcutaneous Insulin Injection technique involving different sensors and actuators in order to enable continued execution of the treatment, as well as detect faults in it. Precisely that is the challenge raised by this example, to design a control system that maintains the delivery of insulin even in the presence of a large number and variety of hardware and software failures. The implementation of this control system has been made in Java using an extension of the DRIP framework, that ensures the reliability properties of systems designed using CAAs. [less ▲]

Covering Different Levels of Evaluation Needs by an Internet-Based Computer-Assisted Testing Framework for Collaborative Distributed Test Development and Delivery

in Proceedings of World Conference on Educational Multimedia, Hypermedia and Telecommunications (2005)

Association between end-tidal pCO2 and negative affect in healthy individuals

in Psychophysiology (2005), 42

Non-invasive measurement of airway inflammation using exhaled nitric oxide: Temporal stability and relationship with climate, air pollution and lung function

in Psychosomatic Medicine (2005)

Increased simultaneity rating of heart beat and bilateral acoustic signals

in Psychophysiology (2005), 42(Supplement 1), 106-106

Ultrafast Phenomena in Freestanding LT-GaAs Devices

in Acta Physica Polonica A (2005), VOL 107; PART 1

We report on the fabrication and high-frequency performance of our photodetectors and photomixers based on freestanding low-temperature-grown GaAs. The MBE-grown low-temperature GaAs layers are lifted ... [more ▼]

We report on the fabrication and high-frequency performance of our photodetectors and photomixers based on freestanding low-temperature-grown GaAs. The MBE-grown low-temperature GaAs layers are lifted from the native GaAs substrate and transferred on top of variety of host substrates. The freestanding devices exhibit breakdown electrical ¯elds above 200 kV/cm and dark currents below 3 £ 10¡7 A at 100 V bias. Device photoresponse shows 0.55 ps wide electrical transients with voltage amplitudes up to 1.3 V, measured using an electro-optical sampling technique with 100 fs wide laser pulses. Photomixing experiments at 460 GHz yield a 9 times higher output power for the freestanding device on Si/SiO2 host substrate compared to the native substrate. [less ▲]

Developing a Collaborative and Autonomous Training and Learning Environment for Hybrid Wireless Networks

in Proceedings of Global Congress on Engineering and Technology Education (GCETE 2005) (2005)

Optical absorption of hexagonal boron nitride and BN nanotubes

in AIP Conference Proceedings (2005), 786

present calculations for the optical absorption spectra of hexagonal boron nitride (hBN) and BN nanotubes, using many-body perturbation theory. Solution of the Bethe-Salpeter equation for hBN leads to ... [more ▼]

present calculations for the optical absorption spectra of hexagonal boron nitride (hBN) and BN nanotubes, using many-body perturbation theory. Solution of the Bethe-Salpeter equation for hBN leads to optical absorption and loss spectra where the positions and shapes of the peaks are strongly dominated by excitonic effects. The binding energy of the first exciton is about 0.71 eV. Comparison of the calculations with recently measured optical absorption and EELS demonstrates that DFT underestimates the "true" band gap of BN by 2.25 eV. This band gap difference can be partially (hot not completely) reproduced by a calculation of the quasi-particle band-structure on the level of the GW-approximation. We show, how the lower dimensionality of BN nanotubes leads to a much stronger excitonic binding energy and at the same time to a larger quasi-particle gap. This leaves the position of the first absorption peak almost unchanged. However, the difference in the series of excitonic peaks allows the spectroscopic distinction between BN nanotubes and bulk BN. [less ▲]

Le droit de l’Union européenne et les Constitutions nationales : primauté ou conciliation ?

in Revue de droit comparé, Institut japonais de droit comparé (2005), 2

Agent-based optimization of business functions using coevolutionary algorithms: the distributed warehouse management case study

in AISTA 2004 (International Conference on Advances in Intelligent Systems - Theory and Applications) organized in cooperation with the IEEE Computer Society (2004)

La structure de la légitimité démocratique : entre monisme et pluralisme, entre symbolique du sujet et ingénierie des pouvoirs

in Revue Universelle des Droits de l'Homme (2004), 16

A methodology for pattern discovery in tennis rallys using the adaptive framework ANIMA

in Workshop Knowledge Discovery in Data Streams. ECML/PKDD 2005 (2004)

An incremental neural-based method to discover temporal skeletons in transactional data streams

in Abstract book of 5th Recent Advances in Soft Computing (RASC 2004) (2004)

Multi-electron dynamics for neutralization of highly charged ions near surfaces

in Vacuum (2004), 73(1), 3-7

We present a simulation of the neutralization of highly charged ions in front of a lithium fluoride surface including the close-collision regime above the surface. The present approach employs a Monte ... [more ▼]

We present a simulation of the neutralization of highly charged ions in front of a lithium fluoride surface including the close-collision regime above the surface. The present approach employs a Monte-Carlo solution of the Liouville master equation for the joint probability density of the ionic motion and the electronic population of the projectile and the target surface. It includes single as well as double particle-hole (de)excitation processes and incorporates electron correlation effects through the conditional dynamics of population strings. For slow projectiles and normal incidence, the ionic motion depends sensitively on the interplay between image acceleration towards the surface and repulsion by an ensemble of positive hole charges in the surface ("trampoline effect"). For Ne10+ we find that image acceleration is dominant and no collective backscattering high above the surface takes place. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

Structural Change of the Tourism on Rügen Island – Developments in the Baltic Seaside Resort Binz since 1990

in Recent Trends in Tourism: The Baltic and the World (2004), (15), 89-98

An optimization of terahertz local oscillators based on LT-GaAs technology

in SPIE (2004), 5498 (2004)

Kulturwissenschaften und Fremdsprachenforschung – Szenen einer Beziehung.

in Pädagogischer Zeitschriftenverlag (2004)

Incremental Discovery of Association Rules with Dynamic Neural Cells

in Workshop on Symbolic Networks. ECAI 2004 (2004)

Angular distribution of highly charged ions transmitted through metallic microcapillaries

in Journal of Electron Spectroscopy and Related Phenomena (2003), 129(2-3), 195-200

The angular distribution of Xe6+ ions with an energy of 800 eV/q transmitted through Ni microcapillaries is studied by a classical trajectory simulation. The results for clean and contaminated by layers ... [more ▼]

The angular distribution of Xe6+ ions with an energy of 800 eV/q transmitted through Ni microcapillaries is studied by a classical trajectory simulation. The results for clean and contaminated by layers of insulating materials of the internal surface of capillary are presented. We show that the angular distributions can be used to identify different phases of hollow ion formation for clean metal surface. We also show that the angular distribution changes dramatically for the case of contaminated surface, i.e. when the image acceleration is depressed. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

WAPIOP - A WAP-based inter-ORB protocol

in Proceedings of 5th European Personal Mobile Communications Conference (Conf Publ No 492) (2003)

Optical absorption in small BN and C nanotubes

in AIP Conference Proceedings (2003), 685

We present a theoretical study of the optical absorption spectrum of small boron-nitride and carbon nanotubes using time-dependent density-functional theory and the random phase approximation. Both for C ... [more ▼]

We present a theoretical study of the optical absorption spectrum of small boron-nitride and carbon nanotubes using time-dependent density-functional theory and the random phase approximation. Both for C and BN tubes, the absorption of light polarized perpendicular to the tube-axis is strongly suppressed due to local field effects. Since BN-tubes are wide band-gap insulators, they only absorb in the ultra-violet energy regime, independently of chirality and diameter. In comparison with the spectra of the single C and BN-sheets, the tubes display additional fine-structure which stems from the (quasi-) one-dimensionality of the tubes and sensitively depends on the chirality and tube diameter. This fine structure can provide additional information for the assignment of tube indices in high resolution optical absorption spectroscopy. [less ▲]

An Overview Of Public-Key Cryptology

in DPP 2003: International Conference on Digital Production Printing and Industrial Applications (2003)

Power Allocation and Bit Loading for Spatial Multiplexing in MIMO Systems

in Proceedings IEEE International Conference on Acoustics, Speech, and Signal Processing (2003)

The power assignment problem is important for Multiple-Input-Multiple-Output (MIMO) systems to achieve high capacity. Although this problem is solved by well-known water filling algorithms, this does not ... [more ▼]

The power assignment problem is important for Multiple-Input-Multiple-Output (MIMO) systems to achieve high capacity. Although this problem is solved by well-known water filling algorithms, this does not provide an optimal solution if the system is constrained to a fixed raw bit error rate threshold and to discrete modulation s. In this work an approximate approach, called QoS based WF, is proposed to solve the power assignment problem with such constrains. It is shown to outperform quantization of the conventional water filling solution and a well known bit loading algorithm (Chow's algorithm) used in the Digital Subscriber Lines (DSL). [less ▲]

Backgating high-current and breakdown characterisation of AlGaN/GaN HEMTs on silicon substrates

in Proceedings of the ESSDERC 2003. Estoril, Portugal (2003)

Backgating effect as well as breakdown and high-current performance of AlGaN/GaN HEMTs on silicon substrates are studied. The material structure of investigated devices differ in the thickness of ... [more ▼]

Backgating effect as well as breakdown and high-current performance of AlGaN/GaN HEMTs on silicon substrates are studied. The material structure of investigated devices differ in the thickness of stressrelaxing intermediate layer sequence (~1 μm and ~2.5 μm thick). It is shown that the transistor backgating effect is reduced for the thicker sequence. Similarly, the reverse gate current is two orders of the magnitude lower and the gate-drain breakdown voltage increases substantially in devices with the thicker sequence. Increase from ~40 V to ~160 V of the HEMT blocking capability measured under electrostatic discharge-like conditions is also observed. [less ▲]

Semidefinite Programming for Detection in Linear Systems - Optimality Conditions and Space-Time Decoding

in IEEE International Conference on Acoustics Speech and Signal Processing (2003)

Optimal maximum likelihood detection of finite alphabet symbols in general requires time consuming exhaustive search methods. The computational complexity of such techniques is exponential in the size of ... [more ▼]

Optimal maximum likelihood detection of finite alphabet symbols in general requires time consuming exhaustive search methods. The computational complexity of such techniques is exponential in the size of the problem and for large problems sub-optimal algorithms are required. In this paper, to find a solution in polynomial time, a semidefinite programming approach is taken to estimate binary symbols in a general linear system. A condition under which the proposed method provides optimal solutions is derived. As an application, the proposed algorithm is used as a decoder for a linear space-time block coding system and the results are illustrated with numerical examples. [less ▲]

Freestanding LT GaAs as a subpicosecond photoconductive switch and high-voltage photomixer

in Abstract book of 4th Symposium on Non-Stoichiometric III-V Compounds (2002), Physik Mikrostrukturierter Halbleiter 27

Varactor Diodes based on an AlGaN/GaN HEMT layer structure

in EProc. EDMO (2001)

Investigations on the influence of traps in AlGaN/GaN HEMTs

in EDMO (2001)