1,853 research outputs found
A new modulation technique for high data rate low power UWB wireless optical communication in implantable biotelemetry systems
We report on the development of a novel modulation technique for UWB wireless optical communication systems for application in a transcutaneous biotelemetry. The solution, based on the generation of short laser pulses, allows for a high data rate link whilst achieving a significant power reduction (energy per bit) compared to the state-of-the-art. These features make this particularly suitable for emerging biomedical applications such as implantable neural/biosensor systems. The relatively simple architecture consists of a transmitter and receiver that can be integrated in a standard CMOS technology in a compact Silicon footprint. These parts include circuits for bias and drive current generation, conditioning and processing, optimised for low-volt age/low-power operation. Preliminary experimental findings validate the new paradigm and show good agreement with expected results. The complete system achieves a BER less than 10-7, with maximum data rate of 125Mbps and estimated total power consumption of less than 3mW
The rare case of positive FDG-positron emission tomography for giant cavernous hemangioma of the liver
Hemangioma is the most common benign liver tumor and the second most common liver tumor after metastases. Large hemangiomas are often heterogeneous. When they exceed 4 cm in diameter, they are termed giant hemangiomas. These giant hemangiomas often present heterogeneous patterns. These heterogeneous appearances are shown because of intratumoral changes due to several
degenerative phenomena. PET/CT is reported to be useful for the differentiation of benign from malignant liver lesions. We report the case of a large hepatic hemangioma characterized by high FDG uptake
Experimental Analysis of Heat Transfer in Passive Latent Heat Thermal Energy Storage Systems for CSP Plants
Abstract Thermal energy storage is a key factor for efficiency, dispatchability and economic sustainability of concentrated solar plants. The latent heat storage systems could ensure a significant reduction in construction costs and environmental impact, because of its high storage energy density. In LHTES, the heat transfer between the heat transfer fluid and the storage system is strongly limited by the reduced thermal conductivity of the storage media. For operating temperatures between 200 and 600 °C, the most used storage media are salts. In order to evaluate solutions which promote the thermal conductivity, by increasing the exchange surface and/or the addition of nanoparticles to the storage media, Enea set up a small facility to test some storage concepts. In this facility, a diathermic oil flows through three elementary "shell-and-tube" storage systems, connected in series, reaching a maximum temperature of about 280 °C. The elementary storage systems are filled with a mixture of sodium and potassium nitrates salts, which melt at about 225 °C. Moreover a small percentage of alumina and silica nanoparticles were added to this mixture. The results of the experiments show an increase of the thermal diffusivity of the medium not only for the presence of fins on the heat transfer tubes but also because of convective flows within the melted fraction were established. These phenomena strongly reduce the charging times of the system (by about 30%). Instead, the presence of nanoparticles increases the thermal capacity and the thermal conductivity of the storage system but seems not to have a relevant effect on the thermal diffusivity of the mixture. This behavior depends on the type of used nanoparticles, which can significantly change over time some characteristics of the storage medium, in which they are dispersed, leaving other characteristics unchanged, according to mechanisms which are still to be well understood
Integration of ground-penetrating radar, ultrasonic tests and infrared thermography for the analysis of a precious medieval rose window
Abstract. The integration of high-resolution, non-invasive geophysical techniques (such as ground-penetrating radar or GPR) with emerging sensing techniques (acoustics, thermography) can complement limited destructive tests to provide a suitable methodology for a multi-scale assessment of the state of preservation, material and construction components of monuments. This paper presents the results of the application of GPR, infrared thermography (IRT) and ultrasonic tests to the 13th century rose window of Troia Cathedral (Apulia, Italy), affected by widespread decay and instability problems caused by the 1731 earthquake and reactivated by recent seismic activity. This integrated approach provided a wide amount of complementary information at different scales, ranging from the sub-centimetre size of the metallic joints between the various architectural elements, narrow fractures and thin mortar fillings, up to the sub-metre scale of the internal masonry structure of the circular ashlar curb linking the rose window to the façade, which was essential to understand the original building technique and to design an effective restoration strategy
Influence of oxidant agent on syngas composition: gasification of hazelnut shells through an updraft reactor
Thermophysical properties of engineering fluids have proven in the past to be essential for the design of physical and chemical processing and reaction equipment in the chemical, metallurgical, and allied industries, as they influence directly the design parameters and performance of plant units in the of, for example, heat exchangers, distillation columns, phase separation, and reactors. In the energy field, the search for the optimization of existing and alternative fuels, either using neutral or ionic fluids, is an actual research and application topic, both for new applications and the sustainable development of old technologies. One of the most important drawbacks in the industrial use of thermophysical property data is the common discrepancies in available data, measured with different methods, different samples, and questionable quality assessment. Measuring accurately the thermal conductivity of fluids has been a very successful task since the late 1970s due to the efforts of several schools in Europe, Japan, and the United States. However, the application of the most accurate techniques to several systems with technological importance, like ionic liquids, nanofluids, and molten salts, has not been made in the last ten years in a correct fashion, generating highly inaccurate data, which do not reflect the real physical situation. It is the purpose of this paper to review critically the best available techniques for the measurement of thermal conductivity of fluids, with special emphasis on transient methods and their application to ionic liquids, nanofluids, and molten salts
Late onset absolute neutropenia associated with ocrelizumab treatment in multiple sclerosis: A case report and review of the literature
Real-time tomography mooring
A real-time tomography system has been developed which combines ocean acoustic tomography with satellite-based time keeping
and satellite telemetry. The basis of the system is the acoustic tomography transceiver and its associated acoustic navigation grid.
To this basic system, a link to the surface has been added to provide a pathway for telemetry of the tomographic data to shore and a downlink for satellite-derived time which is used to correct the transceiver's clock. The surface buoy contains a GPS receiver, clock comparator, system controller and multiple ID Argos transmitters. Processed tomography signals, transceiver location data time, time drift and surface buoy engineering data are transmitted to satellite using a total of 32 data buffers transmitted every eight minutes. The report describes the real-time tomography system in detail, with particular emphasis on the modifications
implemented to convert the standard tomography instrument to a real-time oceanographic tool.Funding was provided by the Office of Naval Technology
under Contract No. N000-14-C-90-0098
Pressure-dependent EPANET extension
In water distribution systems (WDSs), the available flow at a demand node is dependent on the pressure at that node. When a network is lacking in pressure, not all consumer demands will be met in full. In this context, the assumption that all demands are fully satisfied regardless of the pressure in the system becomes unreasonable and represents the main limitation of the conventional demand driven analysis (DDA) approach to WDS modelling. A realistic depiction of the network performance can only be attained by considering demands to be pressure dependent. This paper presents an extension of the renowned DDA based hydraulic simulator EPANET 2 to incorporate pressure-dependent demands. This extension is termed âEPANET-PDXâ (pressure-dependent extension) herein. The utilization of a continuous nodal pressure-flow function coupled with a line search and backtracking procedure greatly enhance the algorithmâs convergence rate and robustness. Simulations of real life networks consisting of multiple sources, pipes, valves and pumps were successfully executed and results are presented herein. Excellent modelling performance was achieved for analysing both normal and pressure deficient conditions of the WDSs. Detailed computational efficiency results of EPANET-PDX with reference to EPANET 2 are included as well
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