927 resultados para universal serial-bus (USB) dongle antennas


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Dissertação apresentada à Escola Superior de Comunicação Social como parte dos requisitos para obtenção de grau de mestre em Audiovisual e Multimédia.

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The use of multicores is becoming widespread inthe field of embedded systems, many of which have real-time requirements. Hence, ensuring that real-time applications meet their timing constraints is a pre-requisite before deploying them on these systems. This necessitates the consideration of the impact of the contention due to shared lowlevel hardware resources like the front-side bus (FSB) on the Worst-CaseExecution Time (WCET) of the tasks. Towards this aim, this paper proposes a method to determine an upper bound on the number of bus requests that tasks executing on a core can generate in a given time interval. We show that our method yields tighter upper bounds in comparison with the state of-the-art. We then apply our method to compute the extra contention delay incurred by tasks, when they are co-scheduled on different cores and access the shared main memory, using a shared bus, access to which is granted using a round-robin arbitration (RR) protocol.

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The usage of COTS-based multicores is becoming widespread in the field of embedded systems. Providing realtime guarantees at design-time is a pre-requisite to deploy real-time systems on these multicores. This necessitates the consideration of the impact of the contention due to shared low-level hardware resources on the Worst-Case Execution Time (WCET) of the tasks. As a step towards this aim, this paper first identifies the different factors that make the WCET analysis a challenging problem in a typical COTS-based multicore system. Then, we propose and prove, a mathematically correct method to determine tight upper bounds on the WCET of the tasks, when they are co-scheduled on different cores.

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The current industry trend is towards using Commercially available Off-The-Shelf (COTS) based multicores for developing real time embedded systems, as opposed to the usage of custom-made hardware. In typical implementation of such COTS-based multicores, multiple cores access the main memory via a shared bus. This often leads to contention on this shared channel, which results in an increase of the response time of the tasks. Analyzing this increased response time, considering the contention on the shared bus, is challenging on COTS-based systems mainly because bus arbitration protocols are often undocumented and the exact instants at which the shared bus is accessed by tasks are not explicitly controlled by the operating system scheduler; they are instead a result of cache misses. This paper makes three contributions towards analyzing tasks scheduled on COTS-based multicores. Firstly, we describe a method to model the memory access patterns of a task. Secondly, we apply this model to analyze the worst case response time for a set of tasks. Although the required parameters to obtain the request profile can be obtained by static analysis, we provide an alternative method to experimentally obtain them by using performance monitoring counters (PMCs). We also compare our work against an existing approach and show that our approach outperforms it by providing tighter upper-bound on the number of bus requests generated by a task.

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Contention on the memory bus in COTS based multicore systems is becoming a major determining factor of the execution time of a task. Analyzing this extra execution time is non-trivial because (i) bus arbitration protocols in such systems are often undocumented and (ii) the times when the memory bus is requested to be used are not explicitly controlled by the operating system scheduler; they are instead a result of cache misses. We present a method for finding an upper bound on the extra execution time of a task due to contention on the memory bus in COTS based multicore systems. This method makes no assumptions on the bus arbitration protocol (other than assuming that it is work-conserving).

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Radio frequency (RF) energy harvesting is an emerging technology that will enable to drive the next generation of wireless sensor networks (WSNs) without the need of using batteries. In this paper, we present RF energy harvesting circuits specifically developed for GSM bands (900/1800) and a wearable dual-band antenna suitable for possible implementation within clothes for body worn applications. Besides, we address the development and experimental characterization of three different prototypes of a five-stage Dickson voltage multiplier (with match impedance circuit) responsible for harvesting the RF energy. Different printed circuit board (PCB) fabrication techniques to produce the prototypes result in different values of conversion efficiency. Therefore, we conclude that if the PCB fabrication is achieved by means of a rigorous control in the photo-positive method and chemical bath procedure applied to the PCB it allows for attaining better values for the conversion efficiency. All three prototypes (1, 2 and 3) can power supply the IRIS sensor node for RF received powers of -4 dBm, -6 dBm and -5 dBm, and conversion efficiencies of 20, 32 and 26%, respectively. © 2014 IEEE.

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Due to the application of active components into antennas these became a source of distortion on wireless communication systems. In this paper we explore the nonlinear effects occurring in a frequency reconfigurable antenna operating with a PIN Diode. We describe the measurement setup used to check the antenna intermodulation products and the measured compression and third order intermodulation limitations of a frequency reconfigurable antenna, operating at the UMTS and WLAN frequencies.

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Numerous studies have documented subtle but consistent sex differences in self-reports and observer-ratings of five-factor personality traits, and such effects were found to show well- defined developmental trajectories and remarkable similarity across nations. In contrast, very little is known about perceived gender differences in five-factor traits in spite of their potential implications for gender biases at the interpersonal and societal level. In particular, it is not clear how perceived gender differences in five-factor personality vary across age groups and national contexts and to what extent they accurately reflect assessed sex differences in personality. To address these questions, we analyzed responses from 3,323 individuals across 26 nations (mean age = 22.3 years, 31% male) who were asked to rate the five-factor personality traits of typical men or women in three age groups (adolescent, adult, and older adult) in their respective nations. Raters perceived women as slightly higher in openness, agreeableness, and conscientiousness as well as some aspects of extraversion and neuroticism. Perceived gender differences were fairly consistent across nations and target age groups and mapped closely onto assessed sex differences in self- and observer-rated personality. Associations between the average size of perceived gender differences and national variations in sociodemographic characteristics, value systems, or gender equality did not reach statistical significance. Findings contribute to our understanding of the underlying mechanisms of gender stereotypes of personality and suggest that perceptions of actual sex differences may play a more important role than culturally based gender roles and socialization processes.

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Contient : « Le livre des parties d'Oultre mer, lequel fu fait, ordonné et compilé par honorable et vaillant seigneur Jehan de Mandeville... Escript (fol. 62) par moy, Ogier de Caumont, en la cité de Liege, et finy le penultieme jour de juillet l'an mil CCC IIIIxx??? et XVI. » Cf. R. Röhricht, Bibliotheca geographica Palestinae, p. 79 ; On lit : « Hunc librum acquisivit monasterio Sancti Victoris prope Parisius frater Johannes Lamasse, dum esset prior ejusdem ecclesie. Scriptum anno Domini 1424 » ; Prière à la Vierge ; « Dit de la rose », pièce en l'honneur de la Vierge ; Les peines de l'enfer ; « Scriptum quoddam super degradatione et combustione quorumdam fratrum ordinis Predicatorum, qui... opinionem suam ab ecclesia damnata de conceptione purissime Virginis matris Domini Jhesu deffendere nitebantur... Actum anno Domini millesimo quingentesimo nono. » Cf. Du Boulay, Historia Universitatis Parisiensis, t. VI, p. 45 ; Pater Noster et Ave Maria, en vers ; Vers sur le plaisir de boire. « Ad primum morsum, nisi potavero mort sum... » (15 vers) ; « Statutum sacre facultatis Theologie studii Parisiensis super materia conceptionis immaculate gloriosissime Virginis... » (1497) ; Paraphrase, en vers français, de l'Ave maris stella ; « Clericus sic ethimologizatur : Per c intelligitur quod sit clarus... » ; « Almalarius (sic), qui loquitur de duobus ebdomadis passionis Christi. Due ebdomade passionis Christi significant duo tempora ante legem et sub lege... » ; Explications, en latin, du Pater et du Credo. « Elegit Dominus Deus noster Jhesus Christus septem apostolos... » ; « Tabula fidei christiane. Septem virtutes principales : fides, spes... » ; Notes de comput. « Ad habendum ciclum solarem, secundum Gallandum, sive litteram dominicalem... » ; Prière à la Vierge ; « La deputaison » ou « le mireur du corps et de l'ame. Une grant vision est en ce livre escripte... » ; Prières à la Vierge ; I ; II ; III ; Note relative à « Jehan Le Mire, jadis trésorier des guerres » (1339) ; La maison de sapience ; Poème moral sur la mort du Christ ; Vers latins, en l'honneur de S. Jean-Baptiste ; « Missa pro evitanda mortalitate, quam dominus papa Clemens sextus constituit et fecit... » ; « Le Testament maistre Jehan de Meun. » Cf. Histoire littéraire, t. XXVIII (1880), p. 416 (art. de P. Paris) ; Roman de Fauvel, par Gervais Du Bus. Cf. Histoire littéraire, t. XXXII (1898), p. 108 (art. de M. G. Paris) ; Vers latins contre les femmes ; Autre pièce contre les femmes ; Autre pièce sur les femmes. « Se j'avoye une fame qui ne me mentist point... » ; Prière. « Doulx Diex, qui es sans fin et sans initium... » ; « Les heures de la Croiz [en vers], ausquellez le pape Jehan XXII donna i an ex xl jours de vray pardon à quelconque persone, qui par devocion dira ceste office du mistère de la Passion Jhesu Crist » ; Prière à la Vierge