7,528 research outputs found
Good work, little soldier: Text and pretext
No full textThis article reads the relation between Denis's Beau Travail and Jean-Luc Godard's 1960 film Le Petit Soldat as a film-on-film variant of film-on-book adaptation. The model informing this reading is not so much intertextual as pretextual. The principal points of contact between the two films discussed are 'actor' (Michel Subor), 'character' (Bruno Forestier) and 'narrator' (Forestier/Galoup). The use in Beau Travail of Le Petit Soldat is compared with and differentiated from the use of Melville's 'Billy Budd, Sailor'. The conclusion arrived at is that the film-on-film relation can be read as a development of the mirror motif borrowed from Godard by Denis, in order to replace abyssal models of intertextual infinity with the finitudes of abyssal reflexivity. This is to offer a model of pretextuality that is not dependent on privileging the pretext: implicit is the suggestion that Beau Travail and Le Petit Soldat may be read as a single, if hybrid, text
A novel design for an RF MEMS resistive switch on PCB substrate
No full textCopyright @ 2008 Stimulation Action on MEM
The point in time: Precise chronology in early godard
No full textThis essay considers the significance of reference to chronologically specific material (including newspapers, magazines, radio broadcasts, graffiti) in Godard’s first three films of the 1960s - Le Petit soldat/The Little Soldier (made 1960, released 1963), Une femme est une femme/A Woman is a Woman (1961) and Vivre sa vie/My Life to Live (1962), and in Pierrot le fou/Crazy Pete (1965) - arguing that such ephemeral traces of a period can serve as a means of access to the political import of these films, and also are part of a larger concern in Godard with questions of time and history, questions that he is still asking thirty or forty years later, in works like Histoire(s) du cinéma/Histories of Cinema (1998) and Éloge de l’amour/In Praise of Love (2001). © Intellect Ltd 2003
Automated detection of prostate cancer using wavelet transform features of ultrasound RF time series
No full textThe aim of this research was to investigate the performance of wavelet transform based features of ultrasound radiofrequency (RF) time series for automated detection of prostate cancer tumors in transrectal ultrasound images. Sequential frames of RF echo signals from 35 extracted prostate specimens were recorded in parallel planes, while the ultrasound probe and the tissue were fixed in position in each imaging plane. The sequence of RF echo signal samples corresponding to a particular spot in tissue imaging plane constitutes one RF time series. Each region of interest (ROI) of ultrasound image was represented by three groups of features of its time series, namely, wavelet, spectral and fractal features. Wavelet transform approximation and detail sequences of each ROI were averaged and used as wavelet features. The average value of the normalized spectrum in four quarters of the frequency range along with the intercept and slope of a regression line fitted to the values of the spectrum versus normalized frequency plot formed six spectral features. Fractal dimension (FD) of the RF time series were computed based on the Higuchi's approach. A support vector machine (SVM) classifier was used to classify the ROIs. The results indicate that combining wavelet coefficient based features with previously proposed spectral and fractal features of RF time series data would increase the area under ROC curve from 93.1% to 95.0%, respectively. Furthermore, the accuracy, sensitivity, and specificity increases to 91.7%, 86.6%, and 94.7%, from 85.7%, 85.2%, and 86.1%, respectively, using only spectral and fractal features. [ABSTRACT FROM AUTHOR]Peer reviewedFinal article publishe
Measures to Address the Lack of Portability of the RF Fingerprints for Radiometric Identification
No full textRadio Frequency (RF) wireless devices can be identified by the RF emissions they produce when transmitting. The reason is that such emissions contain intrinsic features originating from the physical structure and the materials used to build the wireless device itself. These features are usually called RF fingerprints in the literature, and they can be used to uniquely identify a wireless device through a process called radiometric identification. RF fingerprinting can support multifactor authentication of wireless devices in security applications. One of the main unresolved issues in radiometric identification is the lack of portability of the RF fingerprints. The RF emissions are collected by a RF receiver converting them into digital format, from which the fingerprints are extracted. The lack of portability issue is due to the fact that each RF receiver introduces a bias, which degrades the RF fingerprints of the emitting device. As a consequence, RF emissions of the same wireless device collected by different RF receivers will generate different fingerprints for the same wireless device. This issue strongly limits the applicability of RF fingerprinting for security purposes, since we are not afforded to use different RF receivers to perform identification, and the fingerprints are not portable from one receiver to another. In this paper, we propose a novel approach that helps mitigating this portability issue. Our approach is based on the removal of the bias introduced by RF receivers in the frequency domain through the use of one golden reference. The golden reference is used to generate a calibration function, which is then applied to the RF emissions collected by different RF receivers from any other wireless device. The specific approach is empirically validated against a set of ten Internet of Things (IoT) wireless devices (plus the golden reference), and three RF receivers. Our experimental evidence shows that our method is able to alleviate the portability issue at the cost of a minor degradation in identification accuracy.JRC.E.3 - Cyber and Digital Citizens' Securit
Measures to address the lack of portability of the RF fingerprints for radiometric identification
No full textRadio Frequency (RF) wireless devices can be identified by the RF emissions they produce when transmitting. The reason is that such emissions contain intrinsic features originating from the physical structure and the materials used to build the wireless device itself. These features are usually called RF fingerprints in the literature, and they can be used to uniquely identify a wireless device through a process called radiometric identification. RF fingerprinting can support multifactor authentication of wireless devices in security applications. One of the main unresolved issues in radiometric identification is the lack of portability of the RF fingerprints. The RF emissions are collected by a RF receiver converting them into digital format, from which the fingerprints are extracted. The lack of portability issue is due to the fact that each RF receiver introduces a bias, which degrades the RF fingerprints of the emitting device. As a consequence, RF emissions of the same wireless device collected by different RF receivers will generate different fingerprints for the same wireless device. This issue strongly limits the applicability of RF fingerprinting for security purposes, since we are not afforded to use different RF receivers to perform identification, and the fingerprints are not portable from one receiver to another. In this paper, we propose a novel approach that helps mitigating this portability issue. Our approach is based on the removal of the bias introduced by RF receivers in the frequency domain through the use of one golden reference. The golden reference is used to generate a calibration function, which is then applied to the RF emissions collected by different RF receivers from any other wireless device. The specific approach is empirically validated against a set of ten Internet of Things (IoT) wireless devices (plus the golden reference), and three RF receivers. Our experimental evidence demostrates that our method is able to alleviate the portability issue at the cost of a minor degradation in identification accuracy
An RF-Powered DLL-Based 2.4-GHz Transmitter for Autonomous Wireless Sensor Nodes
No full textThis paper presents the system and circuit design of a compact radio frequency (RF)-powered 2.4-GHz CMOS transmitter (TX) to be used for autonomous wireless sensor nodes (WSNs). The proposed TX utilizes the received dedicated RF signal for both energy harvesting as well as frequency synthesis. A TX RF carrier is derived from the received RF signal by means of a delay locked loop and XOR-based frequency multiplier. The 50-Ω load is subsequently driven by a tuned switching RF power amplifier (PA) with 25% duty cycle input for high global efficiency. The design is fabricated in 40-nm CMOS technology and occupies a die area of 0.16 mm2. Experimental results show a rectifier with 36.83% peak efficiency and power management circuit with 120-nA current consumption that enables a low start-up power of -18.4 dBm. The TX outputs a continuous 2.44-GHz RF signal at -2.57 dBm with 36.5% PA drain efficiency and 23.9% global efficiency from a 915-MHz RF input and supports ON-OFF keying modulation.Accepted Author ManuscriptBio-Electronic
A Wideband 2x13-bit All-Digital I/Q RF-DAC
No full textThis paper presents a wideband 2 13-bit in-phase/quadrature-phase (I/Q) RF digital-to-analog converter-based all-digital modulator realized in 65-nm CMOS. The isolation between I and Q paths is guaranteed employing 25% duty-cycle differential quadrature clocks. With a 1.3-V supply and an on-chip power combiner, the digital I/Q transmitter provides more than 21-dBm RF output power within a frequency range of 1.36–2.51 GHz. The peak RF output power, overall system, and drain efficiencies of the modulator are 22.8 dBm, 34%, and 42%, respectively. The measured static noise floor is below 160 dBc/Hz. The digital I/Q RF modulator demonstrates an IQ image rejection and local oscillator leakage of 65 and 68 dBc, respectively. It could be linearized using either of the two digital predistortion (DPD) approaches: a memoryless polynomial or a lookup table. Its linearity is examined using single-carrier 4/16/64/256/1024 quadrature amplitude modulation (QAM), as well as multi-carrier 256-QAM orthogonal frequency-division multiplexing baseband signals while their related modulation bandwidth can be as high as 154 MHz. Employing DPD improves the third-order intermodulation product (IM3) by more than 25 dB, while the measured error vector magnitude for a “single-carrier 22-MHz 64-QAM” signal is better than 28 dB.Microelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc
Bracelet+: Harvesting the Leaked RF Energy in VLC with Wearable Bracelet Antenna
No full textVisible Light Communication (VLC) is widely considered a promising technology for the coming 6G networks. Recent studies show that a VLC transmitter not only emits visible light signals but also leaks RF signals during the transmission. In this work, we devote effort to harvesting the free leaked RF energy from VLC transmissions. We observe that the surrounding objects could help a coil antenna harvest significantly more RF energy. Based on this observation, we propose our system Bracelet+, which involves the human body in the harvesting system to increase the harvested power. After careful analysis of the influence of the human body on the harvested power, we prototype the coil antenna as a bracelet that achieves both high harvested power and convenience for wearing. The average power of the RF energy harvested by our design is 10 larger than that of the conventional coil antenna, without causing any interference to the communication of VLC systems. The harvested power can reach up to micro-watts in our tested scenarios. Such a micro-watt level of harvested energy has the potential to power up ultra-low-power sensors such as temperature sensors and glucose sensors.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Embedded System
RF Energy Harvesting and Wireless Power Transfer for IoT
No full textInternet of Things (IoT) technologies are fast becoming the main connectivity backbone of the data-driven, sustainable society of the future. However, major concerns related to the lack of efficient solutions for powering and maintaining the uninterrupted operation of the growing number of IoT devices is have begun to emerge. In this regard, energy harvesting techniques are an attractive solution, as they allow for the use of externally recharging batteries, and thus may constitute key components of future sustainable IoT networks. This Special Issue focuses specifically on radio frequency (RF) energy harvesting and wireless power transfer technologies, addressing their challenges through diverse perspectives and exploring innovations and practical applications. It comprises 12 research papers from authors across the globe aiming to advance our understanding and unlock the transformative potential of RF-based energy solutions within the evolving IoT landscape
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