30,130 research outputs found

    Development of haptic communication processes between human and machine

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    La ricerca si focalizza sul rapporto tra tecnologie abilitanti e corpo umano. La miniaturizzazione delle tecnologie, unita alla loro maggiore diffusione negli ambienti, porta ad interrogarsi sull’efficacia dell’integrazione di esse con corpo e attività ad esso connesse. Il contesto problematico della ricerca riguarda i dispositivi indossabili e il progetto di soluzioni destinate a risolvere inediti bisogni o potenziare i sensi umani. La letteratura scientifica e i casi studio circoscrivono il piede come efficace piattaforma per la sperimentazione di interfacce aptiche di comunicazione uomo/macchina, atte a connettere il corpo con informazioni referenziate all’ambiente. Il piede, elemento motorio duplice e simmetrico, ha un’elevata qualità percettiva ed è morfologicamente adeguato all’applicazione di tecnologie emergenti. La posizione di soglia, tra spazio e corpo, consente la raccolta di stimoli da entrambe le aree. La bibliografia evidenzia quanto la pressione, rispetto alla vibrazione, sia preferibile nella comunicazione aptica in quanto componente naturale dei linguaggi relazionali del corpo. Dall’analisi multidisciplinare emerge infine l’opportunità di sviluppo del ritmo come componente strutturale dei messaggi. I legami relazionali tra ritmo, corpo e comportamenti umani sono evidenti in molteplici meccanismi: trascinamento ritmico, mimesi ritmica, sincronia. La messa in relazione di piede, pressione e ritmo diventa affordance dello spazio, capace di suggerire, enfatizzare o attivare determinati comportamenti. L’unione di questi elementi è qui definita ritmica podotattile ed esplicitata nella tesi della descrizione delle sue caratteristiche, dalla circoscrizione di campi e azioni applicative e dalla raccolta dati sui test effettuati con i prototipi costruiti. Le analisi quantitative e qualitative dei dati di lettura del movimento e delle emozioni dimostrano quanto l’utilizzo di un linguaggio ritmico aptico nel piede esprima elevate potenzialità di integrazione con il corpo nel rispetto del comfort e dell’equilibrio attentivo nei flussi di azione preesistenti. I risultati aprono riflessioni su nuove applicazioni progettuali nel campo museale, lavorativo e urbano.This research focuses on the relationship between enabling technologies and the human body. Technology miniaturization and its increased use in environments raises questions about its integration capability with the body and its behaviors. The problematic research context concerns wearable devices and the design of solutions to solve novel needs or enhance human senses. Scientific literature and case studies describe human foot as an effective platform for experimenting with haptic interfaces for human/machine communication, capable of connecting the body with site-specific data. The foot, a dual and symmetrical motor element, has a high perceptive quality and is morphologically suitable for emerging technologies application. Its border position, between space and body, allows stimuli collection from both areas. Bibliography indicates how pressure, compared to vibration, is preferable in haptic communication since it is a natural component of the body's relational languages. Finally, the multidisciplinary analysis reveals the opportunity of developing rhythm as a structural component of messages. The relational links between rhythm, body and human behavior are evident in some mechanisms: rhythmic entrainment, rhythmic mimesis, synchrony. The relationship between foot, pressure and rhythm becomes an affordance of the space, capable of suggesting, emphasising or activating behaviors. The podotactile rhythm is presented here as a union of these elements. In this thesis it is described through the characteristics, the fields and actions application and the data collection from the tests carried out using the build prototypes. The quantitative and qualitative analyses of the movement and emotion reading data show how the use of a haptic rhythmic language in the foot expresses high potential for integration with the body while respecting comfort and attentive balance in pre-existing action flows. The results open reflections on several new design application in museum, working and urban contexts

    Genetically Synthesized Supergain Broadband Wire-Bundle Antenna

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    High-gain antennas are essential hardware devices, powering numerous daily applications, including distant point-to-point communications, safety radars, and many others. While a common approach to elevate gain is to enlarge an antenna aperture, highly resonant subwavelength structures can potentially grant high gain performances. The Chu-Harrington limit is a standard criterion to assess electrically small structures and those surpassing it are called superdirective. Supergain is obtained in a case when internal losses are mitigated, and an antenna is matched to radiation, though typically in a very narrow frequency band. Here we develop a concept of a spectrally overlapping resonant cascading, where tailored multipole hierarchy grants both high gain and sufficient operational bandwidth. Our architecture is based on a near-field coupled wire bundle. Genetic optimization, constraining both gain and bandwidth, is applied on a 24-dimensional space and predicts 8.81 dBi realized gain within a half-wavelength in a cube volume. The experimental gain is 6.15 with 13% fractional bandwidth. Small wire bundle structures are rather attractive for designing superscattering and superdirective structures, as they have a sufficient number of degrees of freedom to perform an optimization, and, at the same time rely on simple fabrication-tolerant layouts, based on low-loss materials. The developed approach can be applied to low-frequency (e.g., kHz-MHz) applications, where miniaturization of wireless devices is highly demanded

    Space Surveillance Network Capabilities Evaluation Mission

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    The last years saw the diffusion of nano, pico and femto satellite missions launched by multiple entities thanks to the launch cost reduction and the electronics miniaturization. Such missions usually present limited capabilities in terms of precise orbit determination and extremely small radar and optical cross-sections. Often these missions carry one or more laser retro-reflectors for precise orbit determination but precise orbital measurements cannot be found in the literature. Miniaturized GNSS receivers are also often carried out but due to the experimental nature of such missions, the reliability and time span of such measurements is limited, leaving radar tracking as the only reliable tracking method. Due to the size of such satellites, the signal-to-noise ratio of such radar measurements is typically low and satellite identification (when launched on ride-share launches with a hundred or more other satellites) proves difficult and time-consuming.Being these very small satellites at the edge of the radar detection capabilities and not providing independent orbit determination means, their position uncertainty could be quite significant, leading to an increased orbit collision perceived risk.With this paper, we present a dedicated small satellite formation, made by multiple nano and pico satellites to evaluate the space surveillance network tracking capabilities and limits. The formation is made by a 3U CubeSat to be deployed as part of a rideshare launch. The satellite would be equipped with multiple means to track it, including a GNSS receiver, a set of multiple laser retro-reflectors, and LEDs for optical, laser, and radar tracking, allowing to characterize also different detection means in terms of capabilities. Such a satellite is made of two independent smaller satellites that can be un-docked in orbit upon command, reducing the satellite size and cross-section. This would push the detection limit for the space surveillance networks starting from an already acquired object and with limited clutter around it. Independent laser and GNSS tracking would allow ground measurement validation and validate position estimations. Further pico-satellites would be deployed by each sub-satellite to further push the detection limits and validate up to which size objects are trackable (still optically, radar and GNSS), thanks to miniaturized GNSS receivers already flown by several other missions.Sub-satellite separation is implemented upon command to ensure the process can be followed and executed at lower altitudes to limit the orbital lifetime of eventually hard-to-track small objects that could worsen the space debris problem. Ground characterization (in terms of optical and radar properties) will be performed, also including polarimetric measurements used to identify the separate satellites. All these technologies together would contribute to creating a unique tool to estimate the tracking capabilities of multiple instruments, specifically tailored for very small objects, the hardest to track, as compared to other characterization activities performed on much bigger objects.Space Systems Egineerin

    Recent Advances in Field Effect Transistor Biosensors: Designing Strategies and Applications for Sensitive Assay

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    In comparison with traditional clinical diagnosis methods, field–effect transistor (FET)–based biosensors have the advantages of fast response, easy miniaturization and integration for high–throughput screening, which demonstrates their great technical potential in the biomarker detection platform. This mini review mainly summarizes recent advances in FET biosensors. Firstly, the review gives an overview of the design strategies of biosensors for sensitive assay, including the structures of devices, functionalization methods and semiconductor materials used. Having established this background, the review then focuses on the following aspects: immunoassay based on a single biosensor for disease diagnosis; the efficient integration of FET biosensors into a large–area array, where multiplexing provides valuable insights for high–throughput testing options; and the integration of FET biosensors into microfluidics, which contributes to the rapid development of lab–on–chip (LOC) sensing platforms and the integration of biosensors with other types of sensors for multifunctional applications. Finally, we summarize the long–term prospects for the commercialization of FET sensing systems

    Room-temperature van der Waals 2D ferromagnet switching by spin-orbit torques

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    Emerging wide varieties of the two-dimensional (2D) van der Waals (vdW) magnets with atomically thin and smooth interfaces holds great promise for next-generation spintronic devices. However, due to the lower Curie temperature of the vdW 2D ferromagnets than room temperature, electrically manipulating its magnetization at room temperature has not been realized. In this work, we demonstrate the perpendicular magnetization of 2D vdW ferromagnet Fe3GaTe2 can be effectively switched at room temperature in Fe3GaTe2/Pt bilayer by spin-orbit torques (SOTs) with a relatively low current density of 1.3 10^7A/cm2. Moreover, the high SOT efficiency of \xi_{DL}~0.22 is quantitatively determined by harmonic measurements, which is higher than those in Pt-based heavy metal/conventional ferromagnet devices. Our findings of room-temperature vdW 2D ferromagnet switching by SOTs provide a significant basis for the development of vdW-ferromagnet-based spintronic applications

    InP High Electron Mobility Transistors with InAs-based Channels for High Frequency and Low Noise Applications

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    Indium phosphide based high electron mobility transistors (InP HEMTs) offer outstanding channel transport properties required for high-speed, high-gain and low-noise performance. They are the key components of low-noise receivers, and their field of application includes telecommunications, imaging, spectroscopy and even quantum computing. For years they have been considered as the best option for low-noise amplifiers, where the most critical metrics depend not only on speed and gain but also on noise performance both at room and cryogenic temperatures. Although gate length miniaturization and channel composition optimization enable record cutoff frequencies, noise performance shows a different trend. Further developments in noise of sub-100 nm devices are not achieved due to their increased drain noise. Additionally, vertical device scaling entails higher gate leakage, thus degrading the noise performance even further. This work covers the epitaxial layer optimization of InP HEMTs with InAs channel insets using bandgap engineering and varying the device geometry. Composite channel structures with narrow and wide bandgap materials were implemented to reduce the effects of impact ionization and lower the gate leakage currents while keeping an excellent RF performance. Devices were characterized by extensive DC and RF measurements at room and cryogenic temperatures. To correlate the device results to its circuit behavior, small-signal device modeling was performed for various epitaxial structures. The used small-signal model accounts for the effects of impact ionization and presents excellent agreement between measured and simulated data. Noise performance at room temperature was also investigated by means of noise parameters measurements. Based on the figures-of-merits for different device geometries and layer stacks, further developments in the fabrication technology could be identified, leading to progress in noise performance

    Targeted and untargeted lipidomics of oxygenated metabolites of PUFAs: a new frontier in health and disease

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    Oxylipins are powerful lipid mediators involved in numerous physiological and pathological processes, generated from both omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) via one or more mono- or dioxygen-dependent reactions. The interest in their profiling has considerably grown during recent years, notably in the active field of biomarker discovery. Mass spectrometry-based metabolomics of oxylipins represents a very interesting tool for various applications in clinical research, but the impact of analytical and biological parameters on the variability of oxylipin patterns needs further understanding. The analytical determination of oxylipins still remains challenging, mostly because of their extremely low concentration levels (ppt range). Therefore, particular attention has to be paid on sample pre-treatment to remove matrix interferents and to concentrate analytes, thus increasing the sensitivity as well as improving the detection limits. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, low-cost and low-solvent extraction, and on-line coupling with analytical instruments. Micro-Extraction by Packed Sorbent (MEPS) presents all these desirable characteristics and, thus, it has emerged as a powerful technique, being much more environment-friendly and less expensive than solid-phase extraction (SPE) and liquid-liquid extraction (LLE) approaches. For the first time in this PhD thesis, the very reliable combination of the off-line semi-automated MEPS technique and liquid chromatography-tandem mass spectrometry was applied to the analysis of oxylipins, as isoprostanes, prostaglandins, epoxyeicosatrienoic and hydroxyeicosatetraenoic acids. The MEPS-UHPLC-MS/MS workflow was fully developed and validated for the targeted and non-targeted profiling of oxylipins in a wide array of biological matrices, as Dried Blood Spots (DBSs), oral fluid and plasma. The novel and fast C18-MEPS procedure guaranteed limits of detection much lower than those reported in literature (5-50 ppts), satisfactory recovery (> 85%) and very good intra- and inter-day precision (RSD < 15%) for most of the oxylipins investigated, by substantially reducing the extraction time (10-20 min), the required volume of both solvents (30-500 μL) and samples (50-500 μL). Furthemore, contrary to the SPE, MEPS cartridge was cost-efficient, being reusable up to 100 times without any loss of extraction efficiency (within ± 10%). Our results clearly demonstrated the usefulness of the internal standard addition to improve the analytical performances of the methods, especially for the DBS assay. For the first time, the innovative internal standard addition performed directly on the card before DBS sampling has been demonstrated to be extremely useful for the correction of analyte variation during the critical storage step. This strategy led to a substantial improvement of the entire assay, thus ensuring a broad applicability of the proposed workflow to the clinical field. The validated MEPS-UHPLC-MS/MS platforms were tested within the framework of three exploratory studies aimed at monitoring inflammation status and oxidant injury in preterm newborns suffering from Patent Ductus Arteriosus, in athletes performing an incremental cycle ergometer test and in acute stroke patients. Most of the oxygenated metabolites forming the complex oxylipin network that were detected in our samples (e.g. (F2/E2-isoprostanes, F2-dihomo-isoprostanes and F4-neuroprostanes, epoxyeicosatrienoic acids and hydroxyeicosatetraenoic acids) did not match with the standards and remained unknown. Herein, to greatly expand the repertoire of oxylipins assayed, suspect screening profiling by high resolution mass spectrometry was used, trying to extend the spectrum of oxylipins monitored in humans and provide a foundation for new insight into the role of bioactive lipids in mediating health and disease

    Experimental and Numerical Analysis of Gas Flows in Microchannels and Micro Heat Exchanger

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    Due to increased interest in miniaturization, great attention has been given in the recent decade to the micro heat exchanging systems. Literature survey suggests that there is still a limited understanding of gas flows in micro heat exchanging systems. The aim of the current thesis is to further the understanding of fluid flow and heat transfer phenomenon inside such geometries when a compressible working fluid is utilized. A combined experimental and numerical approach has been utilized in order to overcome the lack of employable sensors for micro dimensional channels. After conducting a detailed comparison between various data reduction methodologies employed in the literature, the best suited methodology for gas microflow experimentalists is proposed. A transitional turbulence model is extensively validated against the experimental results of the microtubes and microchannels under adiabatic wall conditions. Heat transfer analysis of single microtubes showed that when the compressible working fluid is used, Nusselt number results are in partial disagreement with the conventional theory at highly turbulent flow regime for microtubes having a hydraulic diameter less than 250 microns. Experimental and numerical analysis on a prototype double layer microchannel heat exchanger showed that compressibility is detrimental to the thermal performance. It has been found that compressibility effects for micro heat exchangers are significant when the average Mach number at the outlet of the microchannel is greater than 0.1 compared to the adiabatic limit of 0.3. Lastly, to avoid a staggering amount of the computational power needed to simulate the micro heat exchanging systems with hundreds of microchannels, a reduced order model based on the porous medium has been developed that considers the compressibility of the gas inside microchannels. The validation of the proposed model against experimental results of average thermal effectiveness and the pressure loss showed an excellent match between the two

    Efficient GaN-on-Si Power Amplifier Design Using Analytical and Numerical Optimization Methods for 24–30 GHz 5G Applications

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    This paper presents the design procedure of an efficient compact monolithic microwave integrated circuit power amplifier (MMIC PA) in a 0.1 μm GaN-on-Si process for 5G millimeter-wave communication. Load/source-pull simulations were conducted to correctly create equivalent large-signal matching models for stabilized power cells and to determine the optimal impedance domain. The shorted stub with bypass capacitors minimizes the transistor’s output reactance, simplifying the matching objective to an approximate real impedance transformation (IT). With miniaturization as the implementation guide, explicit formulas and tabulated methods based on mathematical analysis were applied to synthesize the filtering matching networks (MNs) for the input and output stages. In addition, a CAD-dependent numerical optimization approach was used for the interstage MN that needs to cope with high IT ratio and complex loads. The continuous-wave (CW) characterization for the proposed two-stage PA demonstrated 19.8 ± 0.7 dB of small-signal gain, very flat output power (Pout) and power-added efficiency (PAE) at 4 dB gain compression of 32–32.4 dBm and 34–34.6%, respectively, over 24–30 GHz, with 37.1% of peak PAE at mid-frequency

    Integrated photodetectors for compact Fourier-transform waveguide spectrometers

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    A Fourier-transform waveguide spectrometer is demonstrated by using HgTe-quantum-dot-based photoconductors with a spectral response up to a wavelength of 2 mu m. The spectral resolution is 50 cm(-1). The total active spectrometer volume is below 100 mu m x 100 mu m x 100 mu m. Extreme miniaturization of infrared spectrometers is critical for their integration into next-generation consumer electronics, wearables and ultrasmall satellites. In the infrared, there is a necessary compromise between high spectral bandwidth and high spectral resolution when miniaturizing dispersive elements, narrow band-pass filters and reconstructive spectrometers. Fourier-transform spectrometers are known for their large bandwidth and high spectral resolution in the infrared; however, they have not been fully miniaturized. Waveguide-based Fourier-transform spectrometers offer a low device footprint, but rely on an external imaging sensor such as bulky and expensive InGaAs cameras. Here we demonstrate a proof-of-concept miniaturized Fourier-transform waveguide spectrometer that incorporates a subwavelength and complementary-metal-oxide-semiconductor-compatible colloidal quantum dot photodetector as a light sensor. The resulting spectrometer exhibits a large spectral bandwidth and moderate spectral resolution of 50 cm(-1) at a total active spectrometer volume below 100 mu m x 100 mu m x 100 mu m. This ultracompact spectrometer design allows the integration of optical/analytical measurement instruments into consumer electronics and space devices.ISSN:1749-4885ISSN:1749-489
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