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  • Open access
  • 90 Reads
The Analysis of Compressed Sensing for Total Variation Minimization and Bregman

1) CS introduces a framework for simultaneous sensing and compression of big size vectors that applies in a range of applications including Optical Imaging and Synthetic Aperture Radar. 2) Total variation minimization, split Bregman, linearized Bregman and sparse reconstruction propose extremely efficient methods for solving optimization problems, which transform l1-norm constrained problems into unconstrained problems by adding penalty term.. In the paper, the main principles of several algorithms are firstly introduced, then optimization iteration steps for algorithms are presented in detail. 3) Next, to research the performances of the algorithms in terms of the convergence and reconstruction precision, a series of numerical experiments for the above algorithms clearly show visual qualities of reconstructed images.4) we analyze the influence of the parameters u and g on iterative performances as well as the difficulties of controlling parameters, making clear the advantage of The Minimum total variation compared to other algorithms, and the low-complexity of Bregman .

  • Open access
  • 175 Reads
Application of a low cost instrumentation in Arctic extreme conditions

The Arctic is recognized to be strongly affected by global warming, experiencing a reduction of about 40% in sea-ice thickness during late summer to early autumn in recent decades. The Arctic Ocean has a great influence on the earth’s climate, however it is still a significant gap in the Global Observing System. For this reason a large amounts of data are required to monitor the variation of physical and biological parameters and to feed forecasting models, in order to better understand the effects of environmental changes on arctic marine ecosystems. The development of flexible, adaptable and low-cost instrumentation plays a key role in marine environmental studies. This is particularly true if we consider an extreme environment like the Arctic Ocean, where oceanographic instrumentation has to solve a series of technical challenges and barriers. Within this scenario a miniaturized and flexible probe was developed to be easily integrated in different type of platforms. This probe is able to acquire temperature, pressure, fluorescence of chlorophyll a, beyond pitch, roll and acceleration. This work shows the preliminary integration of this technology to an experimental remotely operated underwater and semi-submersible vehicle in the Svalbard area, during survey carried out in the framework of the UVASS (Unmanned Vehicles for Autonomous Sensing and Sampling) research project.

  • Open access
  • 62 Reads
How to define the Urban Comfort in the era of smart cities through the use of the Do-It-Yourself approach and new pervasive technologies.

The “Smart” concept applied to the cities intends to improve different fields of the urban context and in particular the life quality of citizens. An important part of the overall well-being is the urban comfort, defined as a function of some environmental parameters. The knowledge and the widespread collection of the geospatial information allow the implementation of a model able to estimate the urban comfort level. In this respect, a dynamic monitoring system was developed following the Do It Yourself (DIY) approach that allow to collect and send data to a cloud server. The article describes the implementation phases of the device and a first experimental application conducted in Milan.

  • Open access
  • 211 Reads
Characterization of near-ground radio propagation channel for wireless sensor network with application in smart agriculture

In this contribution, we present a narrowband radio channel model for a scenario wherein the radio link operates under near ground conditions, occurring on a ZigBee wireless sensor networks applied to smart agriculture. The developed channel model considers the propagation or path loss caused by agriculture fields found in the propagation link when a near ground radio communication occurs. A near-ground network deployment can be useful to avoid tall antenna masts, or once crops grow.

Among the examined scenarios, we analyzed path loss caused when placing the sensor nodes in soil, short and tall grass fields.

In these scenarios, three different transmitting frequencies were used: 868MHz, 2.4GHz and 5.8GHz. We measured the received power when locating both transmitter and receiver antennas at two heights, 20cm and 40cm above ground. The path loss was then estimated as dependent of the radio link range.

In another scenario, measurements of the Signal Strength Indicator were obtained to analyze the communication quality between sensor nodes when placing them at the same two different antenna heights, only for the case of a short grass field. These nodes are working at 2.4GHz under ZigBee protocol.

A comparison between path loss and RSSI results for different antennas heights has been completed.

In the theoretical part, we performed a 3D Ray Launching simulation considering parameters of the ground materials, such as dielectric constant and conductivity.

The results have been employed in a context aware environment based on WSN deployment and integration, applied in a Smart Agriculture use case.

  • Open access
  • 68 Reads
Recent advances in high-frequency oscillations and seizure onset detection using Laplacian electroencephalography via tripolar concentric ring electrodes

Laplacian electroencephalogram signal from novel and noninvasive tripolar concentric ring electrodes has been demonstrated to have superior performance compared to the electroencephalogram from conventional disc electrodes due to its unique capabilities which allow automatic attenuation of common movement and muscle artifacts in applications including brain-computer interface, seizure onset detection, and detection of high-frequency oscillations and seizure onset zones. This review paper covers the recent advances in the fields of high-frequency oscillations and seizure onset detection based on tripolar Laplacian electroencephalography in animal models and human data to improve the diagnostic yield of electroencephalography for epilepsy. Progression of methodologies utilized including integration of multiple sensors using exponentially embedded families and results obtained including a comparison to the results of others as well as to the performance of the same detectors on simultaneously recorded electroencephalogram via conventional disc electrodes is discussed in detail. Specific advantages of using this particular sensor for these particular applications are highlighted. Promising directions for the future work and an overview of currently ongoing research are discussed along with the potential of combining the two detectors and using automatically detected high-frequency oscillations that have been shown to be indicative of early seizure development as auxiliary features for the seizure onset detection.

  • Open access
  • 73 Reads
Zero group velocity Lamb waves in diamond/AlN-based layered structures

Enhancement of devices operating frequency and size reduction are actual challenges in the field of electroacoustic devices development. Piezoelectric resonators showing small size and high Q at GHz range frequency can be fabricated by exploiting the diamond and piezoelectric AlN film technology. The main objective of this paper consists of the modelling study of the Lamb modes propagation in diamond/AlN thin suspended membranes. The membrane consists of a piezoelectric AlN layer, 3.6 μm thick, on top of a diamond  suspended membrane  10 μm thick. This device can be obtained by  standard technological processes, such as the backside Si/diamond/AlN micro-machining: the diamond layer plays the role of a back-etching stop layer, allowing the release of a diamond/AlN suspended membrane.   Disperse software was used to calculate the phase and group velocity dispersion curves of the Lamb modes in diamond/AlN structures. The zero group velocity (ZGV) resonant conditions in the diamond/AlN composite plate, i.e. the frequencies where the mode group velocity vanishes while the phase velocity remains finite, were found. By means of FEM analysis, the propagation of acoustic Lamb waves in the layered structure AlN/diamond has been investigated:  the elastic displacement fields within the composite plate  at frequencies up to 9000 MHz, as well as the wave lengths were calculated, and the acoustic wave types (quasi-symmetric and quasi-antisymmetric modes) of the ZGV points were identified. The ZGV points of a Lamb mode device are associated with an intrinsic energy localization under the metal electrodes: this fact enables the design of acoustic micro-resonators employing only one interdigital transducer (IDT) and no reflectors, thus reducing both the device size and the technological complexity, while the energy confinement is a natural consequence of the selected acoustic mode. At the ZGV points, the mode energy is locally trapped in the source area thus these modes are expected to be highly sensitive to the plate thickness and mechanical properties changes; the applicability of the ZGV resonators for gas sensing was studied.

  • Open access
  • 95 Reads
Characterization of Silicon Nanonet FETs

Silicon nanowire networks (Silicon Nanonets) is an emerging candidate technology for sensor applications. In this work, we characterized FETs (Field Effect Transistor) employing Silicon Nanonet channels. First, we compared the channel impedance among three different silicon nanonet densities: low, medium and high. Second. We compared channel impedance for channel lengths 5µm, 15µm and 30µm. Third, we evaluated the FETs performance as photodiodes. Finally, we examined the long-term stability of the FETs characteristics. We found that shorter and higher density channels have lower impedance and higher current flow. We also measured the change in the drain current of the Si nanonet FET while the He-Ne CW laser with the wavelength of 632nm irradiated its. Impedance increased by about one order-of-magnitude after 6 months of storage in open air as a result of oxidation.

  • Open access
  • 111 Reads
A Domain Specific Language for Smart Cities

In Smart Cities Systems, one of the main problems of its development is the integration of different devices and sensors. Many of them are incompatible with each other (different platforms, communication protocols, etc.)

In this paper a Domain Specific Language (DSL) for Smart Cities is presented. This DSL allow to describe the system of a Smart City using domain concepts, without considering platforms, protocols, etc. This DSL has been developed using a Model Driven Approach (MDA). Has therefore been developed a metamodel, adding additional constraints to validate the language and a textual and graphical syntax to enable the modeling of the Smart City System in an easy and simple way.

  • Open access
  • 70 Reads
Chatter vibration monitoring in the surface grinding process through digital signal processing of acceleration signal

The grinding process is a manufacturing process that is performed at the end of the machining chain. In such step, the workpiece has a high added-value and therefore critical problems are not allowed, as they may lead to scrap and significant financial loss. Regenerative chatter is the most common form of self-excited vibration. It can occur often because most metal cutting operations involve overlapping cuts which can be a source of vibration amplification. The occurrence of the chatter phenomenon in the grinding process is considered a critical problem because it causes several negative effects, such as poor surface quality, unacceptable inaccuracy, and disproportionate tool wear, to name a few. The objective of this research work is to monitor the onset of the chatter phenomenon in grinding of SAE 1045 steel with an aluminum oxide grinding wheel by digital signal processing techniques of the acceleration signals. Experimental tests were performed in a surface grinding machine and using a data acquisition system with sampling frequency of 2 MHz. The data was analyzed with respect to the frequency content and the Ratio of Power (ROP) statistic obtained for normal and chatter conditions. Visual inspections through digital images of the workpieces surfaces were conducted and then chatter frequency was determined. Results showed that the magnitudes related to the frequencies close to 30 Hz change as chatter phenomenon occurs. The ROP shows features related to the chatter vibrations. The methodology presented herein therefore allows for the automation and optimization of the grinding process.

  • Open access
  • 54 Reads
Biosensor with UV spectrophotometric detection

We have previously investigated the application of cellulose dialysis tubing (dialysis membrane) as a biosensor scaffold medium for the forthcoming detection with the UV spectrophotometer.  This was achieved by using small volumes of biological materials, through drying the samples on the dialysis membrane surface.  The outcomes proved the feasibility of this approach as a novel quantitative detection scheme of the bovine serum albumin (BSA) protein.  However, standard deviations seemed to be high, which revealed the necessity of optimization.  Here it is shown that the standard deviations diminish significantly, when dialysis membrane tubing is eliminated and sample is dried directly on the quartz cuvette of the spectrophotometer, in addition to performing the analysis by baseline correction of the data.  These tests were performed also with the BSA protein, for comparability with the previous work that utilized dialysis membrane as the sample application surface.  The detection limit of the current measurements was found to be 5 micromolar, corresponding to approximately 165 nanogram of protein in 0.5 microliter of the sample.  The presented approach is appropriate for the detection of the presence of protein in minute amounts of samples.  It is advantageous also due to the availability of the instrument in almost all laboratories and the presence of portable designs of the instrument as well.  In the future, applicability of the technique is aimed to be tested for DNA detection, to see the possibility of obtaining results with trace amounts of DNA, without using any sample enrichment procedures such as polymerase chain reaction.