Search

This document is intended to present the business case of a research project, more precisely of the Sub-project "The doubly-fed induction generator: Modeling and control of non-linearities”. Non-linearity affects the operation of a real doubly-fed induction generator (DFIG) and as such has to be addressed by models. In two sentences, the Scope of this Sub-project is (1) to determine the extent to which the available methods carry over to the non linear setting, and (2) to investigate different methods, including new ones. The Plan of this Sub-project includes three Stages which may be executed in sequence and may be interleaved by gates (ISO 21502:2020, FIGURE 4). Stage 1: update the literature database; Stage 2: classify articles and book chapters by the methods they propose and by the problems they solve or address; Stage 3: determine the DFIG model which accounts for most of the physical processes in the machine and those properties of the model which are mathematically tractable; if necessary, investigate new methods and suggest the corresponding control algorithms. The Project’s scope falls into the realm of mathematical and physical Methods and Models of complex systems. The interplay between different methods and models will be emphasised during Stage 2. Complexity of the system under investigation, represented by the interaction of different physical processes in the electrical network and in magnetic materials, will be addressed during Stage 3. Risk carried by each Stage can be identified and quantified, the main Risk coming from the inability of answering a research question. Strategies exist, which can mitigate such Risk: they rely on continuous comparison of known different solutions to previously addressed problems. Such comparison characterises the investigation of mathematical models of physical systems: it allows consistency of results to be verified at each stage and suggests a solution by analogy., a.k.a. "synectics" in the Project Management parla

Il Prodotto qui descritto risulta dalla catalogazione e dalla classificazione di documenti riguardanti l’Affare a cui il Superfondo è intitolato. Le Attività che hanno portato al Prodotto iniziarono il 2019-0704 con l’attivazione della piattaforma ARCHIUI e si svolsero in prevalenza nel quadriennio dal 2020 al 2023. Il Prodotto ha due componenti: (1) il Titolario e (2) la rappresentazione di suoi contenuti riordinata cronologicamente e per Attore, rappresentazione della quale si presenta solo un esempio.

In seguito ad interventi di riparazione di una Vasca Orna-mentale si rende necessaria la posa di un tipo di piastrella diverso da quello originario. Questa Relazione Tecnica comprende: 1 - la motivazione; 2 - la definizione degli obiettivi; 3 - il disegno dell’esperimento, limitato alla colorimetria comparativa delle piastrelle rispettivamente in opera e da posare; 4 - i metodi e gli strumenti, fra i quali un metodo radiometrico indiretto definito ed applicato in un precedente Progetto di illuminotecnica; 5 - la descrizione dei materiali esaminati; 6 - la loro colorimetria comparativa basata sulle coordinate CIELab; 7 - la discussione e la conclusione. In quest'ultimo § i due tipi di piastrella, se asciutti, vengono dichiarati "praticamente indistinguibili" ; le differenze cromatiche fra piastrelle bagnate, come espresse da indicatori quantitativi calcolati a partire dalle su dette coordinate CIELab, vengono dichiarate rilevanti. Tuttavia le previste disuniformità di illuminazione della scena portano a dichiarare come difficilmente percettibili le differenze cromatiche fra i due tipi di piastrella, almeno alla distanza di osservazione e sotto l’angolo di vista scelti per l’esperimento.

Il Progetto qui descritto trae origine da accordi verbali dell'Estate del 2022 fra Parti Co-interessate, in seguito ai quali ebbi mandato di esaminare la possibilità di rimettere in servizio due punti-luce, nel seguito ``Lumi'', in un complesso polifunzionale (residenziale, commerciale, direzionale) di 3 Edifici. Gli Edifici sono qui denotati con A, B e C. Le fasi operative del Progetto compresero la diagnosi dei Lumi esistenti che sconsigliò la riparazione in sitū. Seguirono la progettazione, la realizzazione di prototipi e, dopo numerosi esperimenti, l'installazione di due nuovi Lumi puntati, dal terrazzo dell'Edificio C, verso facciate ed intradossi rispettivamente a NW dell'Edificio A ed a N dell'Edificio B. I processi di esecuzione e controllo in questo Progetto furono possibili solo grazie ad un piano di qualità che comprese conoscenze tecniche Progetto-specifiche. Tali conoscenze, basate sulla Radiometria e sull'Ottica geometrica, non solo permisero la progettazione dei nuovi Lumi ma anche l'accertamento della loro qualità come ``prodotto''. A questo scopo venne sviluppato un metodo di analisi di fotografie che riprendono le superficie illuminate. Il metodo è radiometrico indiretto: \underline{radiometrico} perché tratta le superficie diffondenti come diffusori Lambertiani, \underline{indiretto} perché stima la luminanza delle regioni di interesse a partire da fotografia. Dalla luminanza stimata vengono calcolati due valori di contrasto ed un indice di modulazione, che quantificano l'impatto visivo dei Lumi. Questi valori stabiliscono la compatibilità dei Lumi installati con l'ambiente architettonico. La presente relazione viene sottoposta alle Parti interessate, alle quali compete il giudizio sull'accettabilità del prodotto. Sottolineo infine come il metodo radiometrico indiretto qui descritto e giustificato in grande dettaglio sia un ulteriore prodotto del Progetto, valido anche in altri contesti: quindi sollecito chiunque intravveda un'applicazio

This works addresses the processing of thermo-hydraulic data collected by suitable instruments at a Plant made of seepage wells and located in a residential area in Lombardy, a Region of Italy. Water from meteorological events ('rain water') which falls on a building and on the surrounding impervious areas has to be disposed of separately from wastewater e.g., by seepage well plants. The latter need proper management and maintenance plans. Herewith, a research and development Project is outlined, which was started in 2017 with the aim of monitoring and characterising the Plant. The sequence of sub-Projects has included the collection of thermo-hydraulic data. Methods from the qualitative theory of dynamical, non-autonomous systems have made the processing of such data possible and triggered Plant characterisation. A product from the latter activity consists of a mathematical model of thermo-hydraulic processes in the Plant and of a method to estimate the parameters of such model, presented herewith for the first time.

Il codice di calcolo, compreso nell'ambito del Progetto di Tesi, è il prodotto inteso per la didattica dei problemi inversi che si incontrano nelle Scienze dell'Ambiente e nella Geofisica. Il processo fisico è il trasporto del calore in un intervallo ed in condizioni stazionarie. Il modello si applica anche al moto di filtrazione stazionaria di un fluido. I dati sono la temperatura (altrimenti chiamata "potenziale") ed il termine di sorgente. Incognita è la conducibilità. Ammessa l'esistenza, si prendono in esame alcune condizioni in conseguenza delle quali la conducibilità è unica. La Tesi tratta dapprima il problema inverso nel continuo e ricava, per ogni condizione di unicità, la corrispondente stima di stabilità nello spazio funzionale appropriato. (La "stabilità" in Analisi Funzionale ha come corrispettivo la "sensibilità" in Statistica.) Tutti i risultati vengono trasposti nel discreto e tradotti in codice di calcolo, scritto in linguaggio c in ambiente X-windows X11 R4 sotto sistema operativo IBM AIX 3.2.5 su macchina IBM RS/6000 53h. Gli esempi illustrati dalla Guida sono Esempio2, ossia identificazione di conducibilità che si sa essere stazionaria in un punto, Esempio3, ossia identificazione da conducibilità assegnata in un punto, Esempio4, ossia identificazione di conducibilità "auto-identificabile". Testo e fotografie delle schermate compresi nella Guida permettono all'Utente di eseguire le istruzioni e verificarne i risultati. La caratteristica saliente dell'algoritmo e del codice è il calcolo numerico delle costanti che compaiono nelle stime di stabilità. Le costanti desunte in astratto (dall'equazione del difetto) possono così venire confrontate con quelle calcolate per lo specifico esempio. Questa funzione aggiunge valore al prodotto ed accresce il successo a vita intera del Progetto.

The Article addresses an initial-boundary value seepage problem described by a generalised Darcy law. Existence of a solution is proved. Uniqueness, instead, remains an open issue.

The most intuitive example of an orbit (Section 1) is Carnot's cycle represented on the ${p, V}$ plane: it is a path formed by time-ordered ${p, V}$ pairs. Since the \underline{model} of the Carnot engine is known, then the orbit is a \underline{model-driven} result. Examples provided herewith are either model-driven or \underline{data-driven}. The latter are met whenever no model is available of the process which produces the data. Section 2 deals with application to single-cell mRNA sequencing: data have been heuristically represented by many Authors on a phase plane in order to display the dynamics of cell differentiation; the author's contribution consisted of synthesising a dynamical system which could explain the process, thus providing a model-driven application. Section 3 describes an application to groundwater hydraulics: sequences of water column data collected by a hydrometer network are put into orbit; the response of two seepage wells to a rainstorm can be compared. Applications to Public Health include the display of data from the SARS-CoV-2-caused disease (Subsection 4.1) and the dynamics of drinking water contaminants (Subsection 4.2). Finally, an application to Economics (Section 5): normalised balance of payments data from Italy and Germany are compared. In conclusion (Section 6), putting experimental data into orbit may add further insight and suggest a model of the underlying process. However, not all models are systems of just two ordinary differential equations: problems posed by higher dimensional systems are outlined.

The phenomenon of fluorescence is ubiquitous and as such has attracted Scientists' attention for centuries. The challenge is to describe fluorescence as observed in different materials under different conditions by mathematical models having some features in common. Section ``Fluorescence conversion models: Transform kernels or scaling constants ?'' addresses bulk properties of the fluorescent medium and is mainly \underline{literature-driven}: some Articles are quoted in order of appearance, the focus being on whether the fluorescent quantum efficiency turns out to depend or not on the wavelength of excitation. Section ``Approximate propagators in scalar optics'' is mainly \underline{model-driven} and summarises mathematical methods and models in wave propagation which are limited to scalar waves and are ordered by complexity. The relation of said models to radiative transfer theory need not be immediate and as such is a matter of ongoing investigation.

The phenomenon of fluorescence is ubiquitous and as such has attracted Scientists' attention for centuries. The challenge is to describe fluorescence as observed in different materials under different conditions by mathematical models having some features in common. Section ``Fluorescence conversion models: Transform kernels or scaling constants ?'' addresses bulk properties of the fluorescent medium and is mainly \underline{literature-driven}: some Articles are quoted in order of appearance, the focus being on whether the fluorescent quantum efficiency turns out to depend or not on the wavelength of excitation. Section ``Approximate propagators in scalar optics'' is mainly \underline{model-driven} and summarises mathematical methods and models in wave propagation which are limited to scalar waves and are ordered by complexity. The relation of said models to radiative transfer theory need not be immediate and as such is a matter of ongoing investigation.

Three-phase, doubly-fed induction (DFI) machines are key constituents in energy conversion processes. An ideal DFI machine is modeled by inductance matrices which relate electric and magnetic quantities. This work focusses on the algebraic properties of the mutual (rotor-to-stator) inductance matrix L_{sr}: its kernel, range and left zero divisors are determined. A formula for the differentiation of L_{sr} with respect to the rotor angle theta_r is obtained. Under suitable hypotheses L_{sr} and its derivative are shown to admit an exponential representation. A recurrent formula for the powers of the corresponding infinitesimal generator A_0 is provided. Historically, magnetic decoupling and other requirements led to the Blondel-Park transformation which, by mapping electric quantities to a suitable reference frame, simplifies the DGI machine equations. Herewith the transformation in exponential form is axiomatically derived and the infinitesimal generator is related to A_0. Accordingly, a formula for the product of matrices is derived which simplifies the proof of the Electric Torque Theorem. The latter is framed in a Legendre transform context. Finally, a simple, ``realistic'' machine model is outlined, where the three-fold rotor symmetry is broken: a few properties of the resulting mutual inductance matrix are derived.

The article presents discrete schemes aimed at approximately solving the equations of motion of a quasi- or fully incompressible, isothermal single phase fluid in either two or three spatial dimensions.

Multiphase compositional models are discretised by a fully implicit, phase-upwind and two-point finite volume scheme, which is cell-centred. Existence of a weak solution to the initial-boundary value problem in the infinite-dimensional setting is assumed to hold

The highlights of the article under review are: (a) the role of transmission eigenvalues in {Tikhonov} regularisation, (b) the existence of transmission eigenvalues and (c) the relation between inhomogeneities of a scatterer and transmission eigenvalues. Many publications and articles, including the one under review, do not address the following properties: (m1) any material medium exhibits parameters (the matrices A and N of the article), which depend on frequency; (m2) the real and imaginary parts of permittivities and permeabilities are subject to the {Kramers-Kronig} relations.

Si descrivono alcune proprietà qualitative elementari di quei sistemi dinamici che vengono proposti come modello dell'interazione fra preda e predatore. Si distingue fra procedure dato-centriche e modello-centriche. Viene data la definizione assiomatica di sistema dinamico; si delineano gli obiettivi della teoria qualitativa. In relazione ai punti critici si enuncia e si commenta il lemma di Morse. Si presentano le "variazioni su un tema di Volterra" come svolte da A. H. Kolmogorov in "Problemy Kibernetiki" nel 1972, che consistono in un sistema di due equazioni differenziali ordinarie non lineari. Le proprietà dei termini a destra in tali equazioni dànno luogo a diverse classi di sistemi. Di ciascuna classe, tramite la teoria qualitativa, si determinano i punti critici, il comportamento asintotico delle soluzioni, l'esistenza o no di orbite chiuse. A questo scopo occorrono la definizione di omega-limite ed il teorema di Poincaré-Bendixson. La presentazione si conclude con un altro esempio modello-centrico (applicato ad un ecosistema lacustre) e con un quesito dato-centrico (dalla macro-economia).

(a) Given a superconducting spheroid immersed in a stationary magnetic field B⃗ 0[z,r], which is symmetric with respect to z, find the surface currents, and then determine the magnetic energy density and the force acting on the spheroid. (b) Similarly, given a spheroid immersed in an ideal fluid, the velocity field of which is symmetric with respect to z, determine the tangential fluid velocity on the surface, then the pressure and axial force.

Paradigma di Pierre S. de Laplace. Definizione di problema diretto. Definizione di problema inverso. Classi di problemi inversi. Nozione di problema ben posto. Problemi di identificazione. Definizione di stabilità e metodi della sua stima. Tipi di dipendenza continua.

Identificazione della conducibilità (termica, idraulica, ...) in 1 dimensione spaziale. Problema diretto: esistenza, unicità e stabilità della soluzione. Esempio di maggiorazione. Problema inverso: condizioni di unicità da problema di Cauchy regolare. Controesempio di non stabilità. Metodo dell'equazione del difetto. Stima di stabilità. Unicità da problema di Cauchy singolare. Unicità da condizione non locale. Discretizzazione: sistema compartimentale catenario chiuso.

Let ${\mit\Omega}\subset I\hspace{-3pt}R^2$ be bounded by two heteroclinic orbits, ${\mit\Gamma}_1, {\mit\Gamma}_2$ of the $\nabla u$-flow. Then $\nabla\cdot (c \nabla u)=0$ in ${\mit\Omega}$ implies $c\equiv 0$ in $\bar{\mit\Omega}$ [\textsc{Chicone} and \textsc{Gerlach}, 1987]. Let $u\in {\cal C}^2 ({\mit\Omega})\cap{\cal C}^0 (\bar{\mit\Omega})$ be known. The (unique) conductivity $\hat a$, which complies with $\nabla\cdot(\hat a\nabla u)=f$, can be identified by minimising with respect to $b$ the norm of $\nabla\tilde a [b] \times\nabla u - \nabla b\times\nabla p$ under constraints, where $\nabla\cdot(b\nabla p)=f$ and $\tilde a[b]\partial_j u := b\partial_j p$, $j=$ 1 \textbf{or} 2. This is an attempt at justifying the ``comparison model'' algorithm [\textsc{Scarascia} and \textsc{Ponzini}, 1972], which has seen successful practical applications to inverse hydrogeology ever since.

The doubly-fed induction generator (DFIG ) is a key constituent of energy conversion plants. The control of a DFIG is a challenge, whenever the primary energy supply (e.g., the wind velocity field) is characterised by intermittency. The mathematical model and control of a DFIG rely on the Blondel-Park transformation, which is known to simplify the governing equations. The distinctive feature of this contribution consists of showing how the Blondel-Park transformation derives from a set of conditions to be met by a group. Such a group is shown to exist and to continuously depend on one parameter. The uniqueness of its infinitesimal generator is also shown. As an application, the well-known electric torque theorem is proved in a simple way, which relies on a “product of matrices” formula. The latter, in turn, is a by-product of the axiomatic deduction of the Blondel-Park transformation.

The doubly-fed induction generator (DFIG ) is a key constituent of energy conversion plants. The control of a DFIG is a challenge, whenever the primary energy supply (e.g., the wind velocity field) is characterised by intermittency. The mathematical model and control of a DFIG rely on the Blondel-Park transformation, which is known to simplify the governing equations. The distinctive feature of this contribution consists of showing how the Blondel-Park transformation derives from a set of conditions to be met by a group. Such a group is shown to exist and to continuously depend on one parameter. The uniqueness of its infinitesimal generator is also shown. As an application, the well-known electric torque theorem is proved in a simple way, which relies on a “product of matrices” formula. The latter, in turn, is a by-product of the axiomatic deduction of the Blondel-Park transformation.

Let ${\mit\Omega}\subset I\hspace{-3pt}R^2$ be bounded by two heteroclinic orbits, ${\mit\Gamma}_1, {\mit\Gamma}_2$ of the $\nabla u$-flow. Then $\nabla\cdot (c \nabla u)=0$ in ${\mit\Omega}$ implies $c\equiv 0$ in $\bar{\mit\Omega}$ [\textsc{Chicone} and \textsc{Gerlach}, 1987]. Let $u\in {\cal C}^2 ({\mit\Omega})\cap{\cal C}^0 (\bar{\mit\Omega})$ be known. The (unique) conductivity $\hat a$, which complies with $\nabla\cdot(\hat a\nabla u)=f$, can be identified by minimising with respect to $b$ the norm of $\nabla\tilde a [b] \times\nabla u - \nabla b\times\nabla p$ under constraints, where $\nabla\cdot(b\nabla p)=f$ and $\tilde a[b]\partial_j u := b\partial_j p$, $j=$ 1 \textbf{or} 2. This is an attempt at justifying the ``comparison model'' algorithm [\textsc{Scarascia} and \textsc{Ponzini}, 1972], which has seen successful practical applications to inverse hydrogeology ever since.

Inverse problems aimed at locating cracks and voids inside a dielectric medium by means of electromagnetic waves involve knowledge of transmission eigenvalues. The subject has been actively investigated by many Authors for some years and results have been presented in articles and books. Unfortunately, the frequency dependence of dielectric permittivity and magnetic permeability of the material has not been taken into account. A theorem which provides existence and asymptotic properties of real transmission eigenvalues is shown to be physically inconsistent, because it ignores the Kramers-Kronig relations.

Inverse problems aimed at locating cracks and voids inside a dielectric medium by means of electromagnetic waves involve knowledge of transmission eigenvalues. The subject has been actively investigated by many Authors for some years and results have been presented in articles and books. Unfortunately, the frequency dependence of dielectric permittivity and magnetic permeability of the material has not been taken into account. A theorem which provides existence and asymptotic properties of real transmission eigenvalues is shown to be physically inconsistent, because it ignores the Kramers - Kronig relations.

Scattering patterns are made available by the TAOS (Two-dimensional Angle-resolved Optical Scattering) method, which consists of detecting micrometer-sized single airborne aerosol particles and collecting the intensity of the light they scatter from a pulsed, monochromatic laser beam. TAOS patterns have been classified by a learning machine, the training stage of which depends on many control parameters. Patterns due to single bacterial spores (Bq class) have to be discriminated from those produced by outdoor aerosol particles (Kq set) and diesel soot aggregates (sq set), where both Kq and sq are assumed not to contain patterns of bacterial origin. This work describes two directions along which classification continues to develop: the enlargement of the control parameter set and the simultaneous processing of two areas (sectors) selected from the TAOS pattern. The latter algorithm is meant to make the classifier sensitive to simmetry exhibited by some patterns. The available classification scheme is summarized, as well as the rule by which discrimination is rated off-line. Discrimination based on one pattern sector alone scores fewer than 15% false negatives (misclassified Bq patterns) and false positives from Kq and sq. Discrimination based on the symmetry of two pattern sectors fails to recognize 30% of the Bq (bacterial) patterns, whereas < 5% Kq (environmental) patterns are assigned to the Bq class; false positives from sq (diesel) patterns drop to zero. The issue of false positives is briefly discussed in relation to the fraction of airborne bacteria found in aerosols. © 2014 SPIE.

In this study, a methodology based on the analysis of MODIS (MODerate-resolution Imaging Spectroradiometer) time series was developed to estimate post-fire resilience of Alpine vegetation. To this end, satellite images of two vegetation indices (VIs), the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) were used. The analysis was conducted on wildfire affected areas in the Lombardy region (Italy) between 2003 and 2007. Some land surface (LS) descriptors (i.e. mean and maximum VI, growing season start, end and length) were extracted to characterize the time evolution of the vegetation. The descriptors from a burned area were compared to those from an undisturbed adjacent control site by means of analysis of variance (one-way ANOVA). Post-fire resilience was estimated on the basis of the number of subsequent years exhibiting a statistical difference between burned area and control site. The same methodologies were also applied to events aggregated by main land cover (broadleaf forest, prairies and mixed forest). The averaged resilience of broadleaf forest was 5–6 years, whereas prairie ecosystems exhibited a faster response of 0–2 years. Phenological analysis revealed that fire induces a shift of the start and end of growing season in forest ecosystems but has no effect on prairies. The method provides a useful and quantitative insight into complex post-fire vegetation dynamics in the Alps from a remote sensing perspective; results can apply to post-fire forest management and to multi-risk analysis

Two-dimensional angle-resolved optical scattering (TAOS) is an experimental method which collects the intensity pattern of monochromatic light scattered by a single, micron-sized airborne particle. In general, the interpretation of these patterns and the retrieval of the particle refractive index, shape or size alone, are difficult problems. The solution proposed herewith relies on a learning machine (LM): rather than identifying airborne particles from their scattering patterns, TAOS patterns themselves are classified. The LM consists of two interacting modules: a feature extraction module and a linear classifier. Feature extraction relies on spectrum enhancement, which includes the discrete cosine Fourier transform and non-linear operations. Linear classification relies on multivariate statistical analysis. Interaction enables supervised training of the LM. The application described in this article aims at discriminating the TAOS patterns of single bacterial spores (Bacillus subtilis) from patterns of atmospheric aerosol and diesel soot particles. The latter are known to interfere with the detection of bacterial spores. Classification has been applied to a data set with more than 3000 TAOS patterns from various materials. Some classification experiments are described, where the size of training sets has been varied as well as many other parameters which control the classifier. By assuming all training and recognition patterns to come from the respective reference materials only, the most satisfactory classification result corresponds to ≈ 20% false negatives from Bacillus subtilis particles and ≤ 11% false positives from environmental and diesel particles.

A classification algorithm is able to discriminate laser light scattering patterns originating from single bacterial spores from those originating from single airborne aerosol particles that are naturally-occurring.

Measurement of two-dimensional angle-resolved optical scattering (TAOS) patterns is an attractive technique for detecting and characterizing micron-sized airborne particles. In general, the interpretation of these patterns and the retrieval of the particle refractive index, shape or size alone, are difficult problems. By reformulating the problem in statistical learning terms, a solution is proposed herewith: rather than identifying airborne particles from their scattering patterns, TAOS patterns themselves are classified through a learning machine, where feature extraction interacts with multivariate statistical analysis. Feature extraction relies on spectrum enhancement, which includes the discrete cosine FOURIER transform and non-linear operations. Multivariate statistical analysis includes compu- tation of the principal components and supervised training, based on the maximization of a suitable figure of merit. All algorithms have been combined together to analyze TAOS patterns, organize feature vectors, design classification experiments, carry out supervised training, assign unknown patterns to classes, and fuse information from different training and recognition experiments. The algorithms have been tested on a data set with more than 3000 TAOS patterns. The parameters that control the algorithms at different stages have been allowed to vary within suitable bounds and are optimized to some extent. Classification has been targeted at discriminating aerosolized Bacillus subtilis particles, a simulant of anthrax, from atmospheric aerosol particles and interfering particles, like diesel soot. By assuming that all training and recognition patterns come from the respective reference materials only, the most satisfactory classification result corresponds to 20% false negatives from B. subtilis particles and <11% false positives from all other aerosol particles. The most effective operations have consisted of thresholding TAOS patterns in order to reject defective one

Cauchy partial data imply the uniqueness of the potential. Complex geometrical optics solutions are needed to prove the claim.

The main result of the work pertains to uniqueness of the connection, $∇^X$, from Cauchy data in the space subtended by magnetic Schrödinger-Laplace operators

Two-dimension, angle-resolved optical scattering (TAOS) is an experimental technique by which patterns of LASER light intensity scattered by single (micrometer or sub-micrometer sized) airborne particles are collected. In the past 10 years TAOS instrumentation has evolved from laboratory prototypes to field-deployable equipment; patterns are collected by the thousands during indoor or outdoor sampling in short times. Although comparison between experimental and computed scattering patterns has been carried out extensively, there is no satisfactory way to relate a given pattern to the particle it comes from. This paper reports about the ongoing development and implementation of a method which is aimed at classifying patterns, rather than identifying original particles. A machine learning algorithm includes the extraction of morphological features and their multivariate statistical analysis. A classifier is trained and validated in a supervised mode, by relying on patterns from known materials. Then the tuned classifier is applied to the recognition of patterns of unknown origin.

The fluid dynamic model under investigation stems from the tropical climate model [D. M. W. Frierson, A. J. Majda and O. M. Pauluis, Commun. Math. Sci. 2 (2004), no. 4, 591--626; MR2119930 (2006a:86015)] written, under suitable approximations, for the three observables: baroclinic velocity u⃗ , temperature deviation T, and moisture q, all made dimensionless. The interested reader should also look at the references, [D. M. W. Frierson, A. J. Majda and O. M. Pauluis, op. cit.] in particular, in order to fully appreciate the breadth of this paper.

The boundary value problems addressed in the paper physically correspond to electromagnetic scattering by a smooth, open surface S in R3∖S− and include the magnetic-magnetic crack type, the electric-electric screen type, the magnetic-electric and the mixed-mixed types.

SpecCal software for the spectral calibration of high-resolution spectrometers is presented in this manuscript. The software, written in IDL 7.1, allows estimation of the channel central wavelength and the full width at half maximum of a selected spectrometer at several wavelengths across the VNIR range (350-1050. nm). This is achieved through comparison of the position and width of specific solar and terrestrial absorption features, as observed in the measured data, with those observed in simulated MODTRAN4 irradiance data. SpecCal is operated from a user-friendly graphical user interface that allows semiautomatic application of the spectral calibration algorithm at several wavelengths. The proposed software may be exploited as a useful in situ vicarious spectral calibration tool for field spectrometers operating in the VNIR range, which makes it possible to quickly analyze the spectral characteristics of the instruments and their possible variations with time. © 2011 Elsevier Ltd.

For a long time acute eye irritation has been assessed by means of the DRAIZE rabbit test, the limitations of which are known. Alternative tests based on in vitro models have been proposed. This work focuses on the "reconstituted human corneal epithelium" (R-HCE), which resembles the corneal epithelium of the human eye by thickness, morphology and marker expression. Testing a substance on R-HCE involves a variety of methods. Herewith quantitative morphological analysis is applied to optical microscope images of R-HCE cross sections resulting from exposure to benzalkonium chloride (BAK). The short term objectives and the first results are the analysis and classification of said images. Automated analysis relies on feature extraction by the spectrum-enhancement algorithm, which is made sensitive to anisotropic morphology, and classification based on principal components analysis. The winning strategy has been the separate analysis of the apical and basal layers, which carry morphological information of different types. R-HCE specimens have been ranked by gross damage. The onset of early damage has been detected and an R-HCE specimen exposed to a low BAK dose has been singled out from the negative and positive control. These results provide a proof of principle for the automated classification of the specimens of interest on a purely morphological basis by means of the spectrum enhancement algorithm

The Cell Transformation Assay (CTA) is one of the promising in vitro methods used to predict human carcinogenicity. The neoplastic phenotype is monitored in suitable cells by the formation of foci and observed by light microscopy after staining. Foci exhibit three types of morphological alterations: Type I, characterized by partially transformed cells, and Types II and III considered to have undergone neoplastic transformation. Foci recognition and scoring have always been carried visually by a trained human expert. In order to automatically classify foci images one needs to implement some image understanding algorithm. Herewith, two such algorithms are described and compared by performance. The supervised classifier (as described in previous articles) relies on principal components analysis embedded in a training feedback loop to process the morphological descriptors extracted by "spectrum enhancement" (SE). The unsupervised classifier architecture is based on the "partitioning around medoids" and is applied to image descriptors taken from histogram moments (HM). Preliminary results suggest the inadequacy of the HMs as image descriptors as compared to those from SE. A justification derived from elementary arguments of real analysis is provided in the Appendix

Cell Transformation Assays (CTA) rely on the detection of phenotypic changes, namely foci, induced by chemicals (e.g., xenobiotics or candidate drugs) in mammalian cells such as C3H10T1/2 mouse fibroblasts. A focus is a cell colony and as such is made visible by standardized techniques of light microscopy. Foci exhibit a variety of morphological features, by which three "Types" have been defined. Types II and III consist of cells having undergone neoplastic transformation. The assignment of a focus to a Type is based on the evaluation of phenotypic features by a trained human expert. An automated, two-stage morphological classifier of foci is described herewith. Morphological descriptors are extracted from light microscope images by the "spectrum enhancement" algorithm, which separates structure from texture. Said descriptors are submitted to a classifier, the first stage of which is trained to discriminate transformed cells from normal ones and the 2nd stage to discriminate Type III from Type II. The classifier operating in recognition mode (on images not used for training) is satisfactory in terms of confusion matrix entries. The whole procedure is aimed at removing subjectivity from the scoring and classification of foci and thus make CTA a more powerful tool in carcinogenesis studies

The steady state scattering and absorption of light intensity within a two- or three-dimensional bounded domain $B$ with piacewise smooth boundary $\partial B$ are described by the equation $$-\nabla \cdot (a \nabla u) + cu =0$$.

The parabolic integro-differential equation under investigation, $$ {\beta}\partial_t u = Au - m * Au + {\chi}\tag1 $$(1) subject to suitable initial and boundary conditions (BC), represents linear, non-homogeneous diffusion with memory kernel $m = m[t]$, in the space-time domain $Q$.

A numerical method is proposed to simultaneously reconstruct a piecewise constant conductivity ${\mit\sigma}$ and a permittivity ${\mit\epsilon}$ in a one-dimensional layered medium. In addition to the surface current density, the layer stack geometry has to be known.

An apparently "innocuous'' problem derived from the heat equation, namely the determination of the boundary values $u(1,t)$ of the function $u(\cdot,\cdot)$ which satisfies $$ \partial_t u(x,t) =\partial^2_{xx}u(x,t)+a(x)u(x,t),\quad x\in (0,1),\ t\ge 0,\tag1 $$,(1) $$ \gathered u(x,0) = 0,\ x\in [0,1],\quad u(0,t) = 0,\ t\ge 0,\\ u(x_0,t) = f(t),\ 0< x_0 < 1,\ t\ge 0,\endgathered \tag2$$,(2) from knowledge of $a(\cdot)\in {\scr C}^2 ([0,1])$ and $f(\cdot)$, gives rise to a logarithmic estimate for an "approximate solution'' $u_{\delta}(1,t)$, $t\ge 0$.

The accurate spectral characterization of high-resolution spectrometers is required for correctly computing, interpreting, and comparing radiance and reflectance spectra acquired at different times or by different instruments. In this paper, we describe an algorithm for the spectral characterization of field spectrometer data using sharp atmospheric or solar absorption features present in the measured data. The algorithm retrieves systematic shifts in channel position and actual full width at half-maximum (FWHM) of the instrument by comparing data acquired during standard field spectroscopy measurement operations with a reference irradiance spectrum modeled with the MODTRAN4 radiative transfer code. Measurements from four different field spectrometers with spectral resolutions ranging from 0.05 to 3.5 nm are processed and the results validated against laboratory calibration. An accurate retrieval of channel position and FWHM has been achieved, with an average error smaller than the instrument spectral sampling interval

The paper focuses on the asymptotic formula for Dirichlet-to-Neumann maps.

Let $\Omega$ be a an open, bounded sobset of $\bbd R ^2$ with smooth boundary and $D \subset\Omega$ an open subset such that $\Omega - \bar D$ is connected. Let the background conductivity be a symmetric, positive definite matrix and $u$ solve the conductivity equation in $\Omega$ plus suitable boundary conditions.