2,121 research outputs found
Endohedrally confined hydrogen atom with a moving nucleus
We studied the hydrogen atom as a system of two quantum particles in
different confinement conditions; a spherical-impenetrable-wall cavity and a
fullerene molecule cage. The motion is referred to the center of spherical
cavities, and the Schr\"{o}dinger equation solved by means of a Generalized
Sturmian Function expansion in spherical coordinates. The solutions present
different properties from the ones described by the many models in the
literature, where the proton is fixed in space and only the electron is
considered as a quantum particle. Our results show that the position of the
proton (i.e. the center of mas of the H atom) is very sensitive to the
confinement condition, and could vary substantially from one state to another,
from being sharply centered to being localized outside the fullerene molecule.
Interchange of the localization characteristics between the states when varying
the strength of the fullerene cage and mass occurred through crossing
phenomena
A hybrid asymptotic-FVTD method for the estimation of the radar cross section of 3D structures
The Finite Volume Time-Domain (FVTD) method is an effective full-wave technique which allows an accurate computation of the electromagnetic field. In order to analyze the scattering effects due to electrically large structures, it can be combined with methods based on high-frequency approximations. This paper proposes a hybrid technique, which combines the FVTD method with an asymptotic solver based on the physical optics (PO) and the equivalent current method (ECM), allowing the solution of electromagnetic problems in the presence of electrically large structures with small details. Preliminary numerical simulations, aimed at computing the radar cross section of perfect electric conducting (PEC) composite objects, are reported in order to evaluate the effectiveness of the proposed method
Diossido di titanio e alcune sue applicazioni. Spunti didattici
Il diossido di titanio, TiO2, ampiamente utilizzato come pigmento di
colore bianco, \ue8 uno dei materiali pi\uf9 studiati nell\u2019ambito della ricerca per
le sue propriet\ue0 fotocatalitiche. Esso, infatti, contribuisce alla fotodegradazione
di sostanze inquinanti, motivo per cui \ue8 utilizzato nel settore della
purificazione dell\u2019aria e dell\u2019acqua e per la realizzazione di vetri
autopulenti, disponibili commercialmente. Nel presente lavoro viene
suggerito un percorso didattico con l\u2019obiettivo di mettere in evidenza le
propriet\ue0 fotocatalitiche del diossido di titanio oltre che pu\uf2 essere
utilizzato per affrontare concetti fondamentali quali la struttura a bande dei
solidi e la fotocatalisi. Il percorso si articola in pi\uf9 fasi che ricalcano quelle
suggerite nei metodi didattici basati sull\u2019indagine come il protocollo delle
5E dell\u2019approccio IBSE.
Dopo aver assistito a una dimostrazione che illustra le propriet\ue0
fotocatalitiche del diossido di titanio con l\u2019ausilio di un opportuno
pigmento, gli studenti sono guidati nell\u2019indagine dei diversi fattori che
influenzano il processo
An Analysis of Implementation Strategies in a School-wide Vocabulary Intervention
From an improvement research perspective, this study explores strategies used to implement a school-wide vocabulary intervention into language arts instruction at an urban elementary school. Academic language time, an innovative change in the instructional delivery system, allots time and structure for deliberate teaching of cross-disciplinary academic vocabulary as a routine practice in the language arts block. Implementation included a set of core strategies delivered by a university-school purveyor team. Implementation evidence consisting of survey, observation, and interview data was collected over one school year. Quantitative and qualitative analytic techniques were applied to determine effectiveness of the implementation strategies. Results identify strategy characteristics that supported or impeded the implementation process, the valence of strategy patterns, and areas for improvement. The strategy analysis provides fine-grained descriptive information that informs the specification and description of implementation strategies for purposes of innovation and change
Experimental investigation and modelling of diffusion dialysis process for regeneration of acidic pickling solutions
Pickling is one of the key steps in metal finishing industries, where HCl solutions are largely used thus generating significant amounts of spent waste solutions containing high concentrations of metals and acid. The recovery of acid from such waste solutions is thus one of the most beneficial steps for reducing the environmental and economical impact of these processes. Among several separation methods, diffusion dialysis (DD) is becoming more and more attractive thanks to the recent important advances in ion exchange membranes (IEMs) field and because of its clean nature and operational simplicity, low installation and operating costs and low energy consumption [1,2].
In the present work, a single-cell diffusion dialysis module equipped with a FumaTech Anion Exchange Membrane (AEM), operated in a batch mode, has been employed in order to study the effect of some parameters on the efficiency of HCl recovery from waste pickling acidic solutions. In addition, a mathematical model, capable of simulate and predict this process, has been also developed and validated with experimental information.
The laboratory test-rig and procedures have been first evaluated and optimised by measuring salt and water fluxes with artificial NaCl solutions with different types of AEMs. Then, experiments with HCl solutions were carried out, at different compositions of diffusate and retentate streams, varying HCl concentration values in the range of 0.1-3 M. HCl and water osmotic fluxes were measured and their dependence on operating conditions was identified. Also the effect of the presence of selected iron salts were investigated in order to simulate the operation of the system when treating actual pickling solutions. In particular, the acid diffusion permeability as well as the water osmotic permeability tend to increase when increasing the solution concentration. In addition, an increasing HCl recovery is detected in the presence of iron chloride.
References
[1] Luo et al., Diffusion dialysis processes of inorganic acids and their salts: the permeability of different acidic anions, Separation and Purification Technology 78 (2011), 97-102
[2] Xu et al., Recovery of hydrochloric acid from the waste acid solution by diffusion dialysis, Journal of Hazardous Materials 165 (2009), 832-83
Hétérogénéité et échelles spatiales en milieu corallien : vers la définition d'une stratégie de description optimale des habitats
Double Channel Neural Non Invasive Blood Pressure Prediction
Cardiovascular Diseases represent the leading cause of deaths in the world. Arterial Blood Pressure (ABP) is an important physiological parameter that should be properly monitored for the purposes of prevention. This work applies the neural network output-error (NNOE) model to ABP forecasting. Three input configurations are proposed based on ECG and PPG for estimating both systolic and diastolic blood pressures. The double channel configuration is the best performing one by means of the mean absolute error w.r.t the corresponding invasive blood pressure signal (IBP); indeed, it is also proven to be compliant with the ANSI/AAMI/ISO 81060-2:2013 regulation for non invasive ABP techniques. Both ECG and PPG correlations to IBP signal are further analyzed using Spearman’s correlation coefficient. Despite it suggests PPG is more closely related to ABP, its regression performance is worse than ECG input configuration one. However, this behavior can be explained looking to human biology and ABP computation, which is based on peaks (systoles) and valleys (diastoles) extraction
Development and Validation of an Algorithm for the Digitization of ECG Paper Images
The electrocardiogram (ECG) signal describes the heart’s electrical activity, allowing it to detect several health conditions, including cardiac system abnormalities and dysfunctions. Nowadays, most patient medical records are still paper-based, especially those made in past decades. The importance of collecting digitized ECGs is twofold: firstly, all medical applications can be easily implemented with an engineering approach if the ECGs are treated as signals; secondly, paper ECGs can deteriorate over time, therefore a correct evaluation of the patient’s clinical evolution is not always guaranteed. The goal of this paper is the realization of an automatic conversion algorithm from paper-based ECGs (images) to digital ECG signals. The algorithm involves a digitization process tested on an image set of 16 subjects, also with pathologies. The quantitative analysis of the digitization method is carried out by evaluating the repeatability and reproducibility of the algorithm. The digitization accuracy is evaluated both on the entire signal and on six ECG time parameters (R-R peak distance, QRS complex duration, QT interval, PQ interval, P-wave duration, and heart rate). Results demonstrate the algorithm efficiency has an average Pearson correlation coefficient of 0.94 and measurement errors of the ECG time parameters are always less than 1 mm. Due to the promising experimental results, the algorithm could be embedded into a graphical interface, becoming a measurement and collection tool for cardiologists
A social constructed human beeing : a (bio)technological approach
As a social construction, (bio)technology1 should not be studied out of the social field. From a Social Imaginaries approach, (bio)technology can be considered as a contemporary social magma formed by biological, technical, psychological, sociological and axiological factors. Orbiting around the the cyborg metaphor, in this article we intend to build a multidisciplinary approach of this polycontextureComo una construcción social, la (bio)tecnologÃa no debe ser estudiada fuera del campo social. Desde una perspectiva analÃtica sobre los imaginarios sociales, la (bio)tecnologÃa puede ser considerada como un magma social formado por factores biológicos, técnicos, psicológicos, sociológicos y axiológicos. Orbitando alrededor de la metáfora del cyborg, en este artÃculo nos proponemos construir un enfoque multidisciplinar de esta polycontextura
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