Showing papers by "Marco Parvis published in 2015"
TL;DR: This paper describes an alternative low-cost solution, which is based on a logarithmic front-end and on an off-the-shelf microcontroller board, which remains below $100, while still having the capability of measuring over a frequency range of 0.01 Hz-100 kHz and for impedance values in the range of 100 Ω-10 GQ.
Abstract: Impedance spectroscopy (IS) involves measurements of impedance amplitudes, which often span more than six/seven decades. Currently available IS systems employ sophisticate front-ends to cope with this wide impedance range and, consequently, the cost of the measuring instrument greatly increases. This paper describes an alternative low-cost solution, which is based on a logarithmic front-end and on an off-the-shelf microcontroller board. Using these components, the cost remains below $100, while still having the capability of measuring over a frequency range of 0.01 Hz–100 kHz and for impedance values in the range of $100 {~\mathrm {\Omega }}$ – $10 {~\mathrm {G \Omega }}$ . The overall uncertainty remains below 5% of amplitude and few degrees of phase. The proposed system is, therefore, suitable for electrochemical impedance spectroscopy applications, as well as for bioelectrical impedance analysis.
40 citations
11 May 2015
TL;DR: A faster solution based on the image wavelet decomposition followed by a non-linear processing based on an artificial neural network is described and the results are compared with the one obtained by the traditional direct mass transfer coefficient measurement.
Abstract: This paper investigates the use of a wavelet image decomposition applied to electron microscope images in order to estimate the mass transfer coefficient of pharmaceutical cakes obtained by freeze-drying. The structure analysis of dried cakes obtained by means of a free-drying process, is a basic step for tuning the process conditions and for monitoring the quality of the dried product. The product structure and specifically its porosity affects the drying duration as it defines the resistance to the vapor flow during the ice sublimation. This parameter is becoming quite important as it is fundamental for modeling of the freeze-drying process and thus for an optimal design of the freeze-drying cycle. The direct measurement of this parameter is quite complex thus new simple approaches are being developed for its non-invasive estimation. This paper discusses the possibility of processing SEM images of the dried cake to analyze its morphology and to estimate the mass transfer coefficient. This approach has already been followed by processing the images via a 2D-FFT, here a faster solution based on the image wavelet decomposition followed by a non-linear processing based on an artificial neural network is described and the results are compared with the one obtained by the traditional direct mass transfer coefficient measurement.
4 citations
07 May 2015
TL;DR: Preliminary results obtained by employing Spark Plasma Sintering (SPS) to produce a magnesium foam with a porosity able to stimulate the bone growth are described.
Abstract: The use of temporary implants, which is widely diffused in orthopedic surgery requires surgical procedures to remove the implants after bone healing. A bioresorbable implant, which does not need to be surgically removed, would reduce both patient morbidity and risks of future diseases. Thanks to their biocompatibility, magnesium and its alloys have been proposed for self-degrading implants; moreover, Mg-based implants with a porous structure can stimulate the bone growth. This paper describes the preliminary results obtained by employing Spark Plasma Sintering (SPS) to produce a magnesium foam with a porosity able to stimulate the bone growth.
2 citations
Posted Content•
TL;DR: In this article, a review of potential eco-friendly gas candidate replacements is presented, based on the properties of potential F-based gas candidate replacement detectors for particle detection, and a comparison of their performance.
Abstract: Modern gas detectors for detection of particles require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. This review studies properties of potential eco-friendly gas candidate replacements.
1 citations
Posted Content•
TL;DR: In this article, a model was developed with COMSOL Multhiphysics v. 4.3, which described the adsorption and diffusion within the geometry of GEM foil, the concentration profiles and the time required to saturate the foil.
Abstract: Systematic studies on the GEM foil material are performed to measure the moisture diffusion rate and saturation level. These studies are important because the presence of this compound inside the detector's foil can possibly change its mechanical and electrical properties and, in such a way, the detector performance can be affected. To understand this phenomenon, a model is developed with COMSOL Multhiphysics v. 4.3, which described the adsorption and diffusion within the geometry of GEM foil, the concentration profiles and the time required to saturate the foil. The COMSOL model is verified by experimental observations on a GEM foil sample. This note will describe the model and its experimental verification results.