935 resultados para Transceiver architectures
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Référence bibliographique : Weigert, 427
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Référence bibliographique : Weigert, 431
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Référence bibliographique : Weigert, 433
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Référence bibliographique : Weigert, 434
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Référence bibliographique : Weigert, 435
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Diffusion magnetic resonance studies of the brain are typically performed using volume coils. Although in human brain this leads to a near optimal filling factor, studies of rodent brain must contend with the fact that only a fraction of the head volume can be ascribed to the brain. The use of surface coil as transceiver increases Signal-to-Noise Ratio (SNR), reduces radiofrequency power requirements and opens the possibility of parallel transmit schemes, likely to allow efficient acquisition schemes, of critical importance for reducing the long scan times implicated in diffusion tensor imaging. This study demonstrates the implementation of a semiadiabatic echo planar imaging sequence (echo time=40 ms, four interleaves) at 14.1T using a quadrature surface coil as transceiver. It resulted in artifact free images with excellent SNR throughout the brain. Diffusion tensor derived parameters obtained within the rat brain were in excellent agreement with reported values.
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This paper deals with the design of nonregenerativerelaying transceivers in cooperative systems where channel stateinformation (CSI) is available at the relay station. The conventionalnonregenerative approach is the amplify and forward(A&F) approach, where the signal received at the relay is simplyamplified and retransmitted. In this paper, we propose an alternativelinear transceiver design for nonregenerative relaying(including pure relaying and the cooperative transmission cases),making proper use of CSI at the relay station. Specifically, wedesign the optimum linear filtering performed on the data to beforwarded at the relay. As optimization criteria, we have consideredthe maximization of mutual information (that provides aninformation rate for which reliable communication is possible) fora given available transmission power at the relay station. Threedifferent levels of CSI can be considered at the relay station: onlyfirst hop channel information (between the source and relay);first hop channel and second hop channel (between relay anddestination) information, or a third situation where the relaymay have complete cooperative channel information includingall the links: first and second hop channels and also the directchannel between source and destination. Despite the latter beinga more unrealistic situation, since it requires the destination toinform the relay station about the direct channel, it is useful as anupper benchmark. In this paper, we consider the last two casesrelating to CSI.We compare the performance so obtained with theperformance for the conventional A&F approach, and also withthe performance of regenerative relays and direct noncooperativetransmission for two particular cases: narrowband multiple-inputmultiple-output transceivers and wideband single input singleoutput orthogonal frequency division multiplex transmissions.
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In The Cognitive-Emotional Brain, Pessoa (2013) suggests that cognition and emotion should not be considered separately. We agree with this and argue that cognitive architectures can provide steady ground for this kind of theory integration and for investigating interactions among underlying cognitive processes. We briefly explore how affective components can be implemented and how neuroimaging measures can help validate models and influence theory development.
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Tämä diplomityö käsittelee sääntöpohjaisen verkkoon pääsyn hallinnan (NAC) ratkaisuja arkkitehtonisesta näkökulmasta. Työssä käydään läpi Trusted Computing Groupin, Microsoft Corporationin, Juniper Networksin sekä Cisco Systemsin NAC-ratkaisuja. NAC koostuu joukosta uusia sekä jo olemassa olevia teknologioita, jotka auttavat ennalta määriteltyyn sääntökantaan perustuen hallitsemaan suojattuun verkkoon pyrkivien laitteiden tietoliikenneyhteyksiä. Käyttäjän tunnistamisen lisäksi NAC pystyy rajoittamaan verkkoon pääsyä laitekohtaisten ominaisuuksien perusteella, esimerkiksi virustunnisteisiin ja käyttöjärjestelmäpäivityksiin liittyen ja paikkaamaan tietyin rajoituksin näissä esiintyviä puutteita verkkoon pääsyn sallimiseksi. NAC on verraten uusi käsite, jolta puuttuu tarkka määritelmä. Tästä johtuen nykymarkkinoilla myydään ominaisuuksiltaan puutteellisia tuotteita NAC-nimikkeellä. Standardointi eri valmistajien NAC-komponenttien yhteentoimivuuden takaamiseksi on meneillään, minkä perusteella ratkaisut voidaan jakaa joko avoimia standardeja tai valmistajakohtaisia standardeja noudattaviksi. Esitellyt NAC-ratkaisut noudattavat standardeja joko rajoitetusti tai eivät lainkaan. Mikään läpikäydyistä ratkaisuista ei ole täydellinen NAC, mutta Juniper Networksin ratkaisu nousee niistä potentiaalisimmaksi jatkokehityksen ja -tutkimuksen kohteeksi TietoEnator Processing & Networks Oy:lle. Eräs keskeinen ongelma NAC-konseptissa on työaseman tietoverkolle toimittama mahdollisesti valheellinen tietoturvatarkistuksen tulos, minkä perusteella pääsyä osittain hallitaan. Muun muassa tähän ongelmaan ratkaisuna voisi olla jo nykytietokoneista löytyvä TPM-siru, mikä takaa tiedon oikeellisuuden ja koskemattomuuden.
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Peer-reviewed
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Technological developments in microprocessors and ICT landscape have made a shift to a new era where computing power is embedded in numerous small distributed objects and devices in our everyday lives. These small computing devices are ne-tuned to perform a particular task and are increasingly reaching our society at every level. For example, home appliances such as programmable washing machines, microwave ovens etc., employ several sensors to improve performance and convenience. Similarly, cars have on-board computers that use information from many di erent sensors to control things such as fuel injectors, spark plug etc., to perform their tasks e ciently. These individual devices make life easy by helping in taking decisions and removing the burden from their users. All these objects and devices obtain some piece of information about the physical environment. Each of these devices is an island with no proper connectivity and information sharing between each other. Sharing of information between these heterogeneous devices could enable a whole new universe of innovative and intelligent applications. The information sharing between the devices is a diffcult task due to the heterogeneity and interoperability of devices. Smart Space vision is to overcome these issues of heterogeneity and interoperability so that the devices can understand each other and utilize services of each other by information sharing. This enables innovative local mashup applications based on shared data between heterogeneous devices. Smart homes are one such example of Smart Spaces which facilitate to bring the health care system to the patient, by intelligent interconnection of resources and their collective behavior, as opposed to bringing the patient into the health system. In addition, the use of mobile handheld devices has risen at a tremendous rate during the last few years and they have become an essential part of everyday life. Mobile phones o er a wide range of different services to their users including text and multimedia messages, Internet, audio, video, email applications and most recently TV services. The interactive TV provides a variety of applications for the viewers. The combination of interactive TV and the Smart Spaces could give innovative applications that are personalized, context-aware, ubiquitous and intelligent by enabling heterogeneous systems to collaborate each other by sharing information between them. There are many challenges in designing the frameworks and application development tools for rapid and easy development of these applications. The research work presented in this thesis addresses these issues. The original publications presented in the second part of this thesis propose architectures and methodologies for interactive and context-aware applications, and tools for the development of these applications. We demonstrated the suitability of our ontology-driven application development tools and rule basedapproach for the development of dynamic, context-aware ubiquitous iTV applications.
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Today's networked systems are becoming increasingly complex and diverse. The current simulation and runtime verification techniques do not provide support for developing such systems efficiently; moreover, the reliability of the simulated/verified systems is not thoroughly ensured. To address these challenges, the use of formal techniques to reason about network system development is growing, while at the same time, the mathematical background necessary for using formal techniques is a barrier for network designers to efficiently employ them. Thus, these techniques are not vastly used for developing networked systems. The objective of this thesis is to propose formal approaches for the development of reliable networked systems, by taking efficiency into account. With respect to reliability, we propose the architectural development of correct-by-construction networked system models. With respect to efficiency, we propose reusable network architectures as well as network development. At the core of our development methodology, we employ the abstraction and refinement techniques for the development and analysis of networked systems. We evaluate our proposal by employing the proposed architectures to a pervasive class of dynamic networks, i.e., wireless sensor network architectures as well as to a pervasive class of static networks, i.e., network-on-chip architectures. The ultimate goal of our research is to put forward the idea of building libraries of pre-proved rules for the efficient modelling, development, and analysis of networked systems. We take into account both qualitative and quantitative analysis of networks via varied formal tool support, using a theorem prover the Rodin platform and a statistical model checker the SMC-Uppaal.