Alessandra Micheletti

Alessandra Micheletti
University of Milan | UNIMI · Department of Mathematics

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55
Publications
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471
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Publications

Publications (55)
Preprint
Full-text available
Estimations and evaluations of the main patterns of time series data in groups benefit large amounts of applications in various fields. Different from the classical auto-correlation time series analysis and the modern neural networks techniques, in this paper we propose a combination of functional analysis of variance (FANOVA) and permutation tests...
Preprint
Full-text available
Gaussian Processes are a powerful tool for shape modelling. While the existing methods on this area prove to work well for the general case of the human head, when looking at more detailed and deformed data, with a high prevalence of missing data, such as the ears, the results are not satisfactory. In order to overcome this, we formulate the shape...
Article
Full-text available
We present a class of iterative fully distributed fixed point methods to solve a system of linear equations, such that each agent in the network holds one or several of the equations of the system. Under a generic directed, strongly connected network, we prove a convergence result analogous to the one for fixed point methods in the classical, centr...
Article
Full-text available
Greening payment represents one of the main and controversial novelties of the current Common Agricultural Policy (CAP) 2015–2020 programming period. Such payments bind a portion of farm subsidies to compliance with specified practices, such as crop diversification. Unlike previous ex ante simulations, the present contribution attempts to estimate...
Chapter
In the present era, which is characterized by an unprecedented deluge of data, coming from many diversified sources, classical optimization methods often are not able to reach the target of finding “the best solution” to a mathematical problem. In this context, methods that imitate natural phenomena, and in particular animal behavior, have proven t...
Article
Full-text available
The problem of detecting a major change point in a stochastic process is often of interest in applications, in particular when the effects of modifications of some external variables, on the process itself, must be identified. We here propose a modification of the classical Pearson \(\chi ^2\) test to detect the presence of such major change point...
Article
Full-text available
This paper represents a preliminary attempt to evaluate ex-post impact of the CAP greening payment on farmland use changes, testing by a Markov Chain approach whether farmland use transitions dynamics changed after the introduction of this new policy instrument. Unlike previous contributions, relying on ex-ante simulations, this analysis is based o...
Article
Full-text available
Common clustering algorithms require multiple scans of all the data to achieve convergence, and this is prohibitive when large databases, with data arriving in streams, must be processed. Some algorithms to extend the popular K-means method to the analysis of streaming data are present in literature since 1998 (Bradley et al. in Scaling clustering...
Article
Common clustering algorithms require multiple scans of all the data to achieve convergence, and this is prohibitive when large databases, with millions of data, must be processed. Some algorithms to extend the popular K-means method to the analysis of big data are present in literature since the publication of (Bradley et al, Scaling clustering alg...
Article
Full-text available
The mechanical properties of dual Phase steels (DP steels) are strictly related to the spatial distribution and the geometry of the two phases composing the steel, ferrite and martensite. Due to the high costs to obtain images of sections of steel samples, one important industrial problem is the reduction of the number of 2D sections needed to buil...
Conference Paper
Dual Phase steel (DP steel) has shown high potential for automotive and other applications, due to its remarkable combined properties of high strength and good formability. The mechanical properties of the material are strictly related to the spatial distribution of the two steel phases, ferrite and martensite, and with their stochastic geometry. U...
Article
Dual Phase steels (DP steels) have shown high potential for automotive and other applications, due to their remarkable property combination between high strength and good formability. The mechanical properties of the material are strictly related with the spatial distribution of the two phases composing the steel, ferrite and martensite, and their...
Article
Full-text available
Background: The Internet is becoming more commonly used as a tool for disease surveillance. Similarly to other surveillance systems and to studies using online data collection, Internet-based surveillance will have biases in participation, affecting the generalizability of the results. Here we quantify the participation biases of Influenzanet, an...
Chapter
Here a description of the history and the main characteristics of the ECMI Educational Programme in Mathematics for Industry is provided. The Programme started in 1987 and evolved in time, according to the increasing new requirments coming both from the industrial and academic world. It is now running since 25 years and the success and brilliant ca...
Article
Many objects in the real world can be modeled as fibres (i.e., lines in 2D or 3D space). If the process is invariant under translations, one of its characteristics is the mean length per unit area (called intensity). Under suitable conditions, two estimators of the intensity have been shown to be asymptotically normal when the sample is “enriched”...
Article
Full-text available
Stationary fibre processes are processes of curves in a higher dimensional space, whose distribution is translation invariant. In practical applications, they can be used to model several real objects, such as roots, vascular networks and fibres of materials. Often it is required to compare processes showing similar shape, thus a quantitative appro...
Article
This special issue gathers together papers presented during the workshop Shape and Size in Medicine, Biotechnology, Materials Science and Social Sciences, Milano, Italy, 16-17 February 2011, https://sites.google.com/site/shapemilan/home
Article
Full-text available
This special issue gathers together papers presented during the workshop Shape and Size in Medicine, Biotechnology, Materials Science and Social Sciences, Milano, Italy, 16-17 February 2011, https://sites.google.com/site/shapemilan/home
Conference Paper
In this paper a method for estimating and forecasting the demand of ambulance service in the area of Milano is presented. We assume that time and location of an emergency service request are outcomes of a space-time marked point process. Thus we estimate the intensity of the process on the basis of the records of specific emergency call history ove...
Article
We consider a birth and growth model for crystallization processes in d space dimensions, where growth is driven by the gradient of the concentration. A nonlinear condition for the concentration is given on the boundary and a multi-front moving boundary problem arises. We propose a new formulation based on the Schwartz distributions by coupling the...
Article
In the modelling and statistical analysis of tumor-driven angiogenesis it is of great importance to handle random closed sets of different (though integer) Hausdorff dimensions, usually smaller than the full dimension of the relevant space. Here an original approach is reported, based on random generalized densities (distributions) á la Dirac-Schwa...
Chapter
Full-text available
Here the theory of size functions is introduced and joined to some statistical techniques in order to build confidence regions for a family of random shapes. An algorithm for the computation of the discrete counterpart of the size functions is also introduced. The method is applied to the quality control of shapes impressed with a laser on a silico...
Chapter
Here the Theory of Size Functions is introduced and joined to some statistical techniques of discriminant analysis, to perform automatic classification of families of random shapes. The method is applied to the classification of normal and malignant tumor cell nuclei, described via their section profiles. The results here reported are compared with...
Chapter
It has been a great honour for me to deliver the “Alan Tayler Lecture” in this ECMI Conference, to honour one of the leading founders and Presidents of ECMI. I have collaborated with Alan for many years, especially during my term as Chairman of the Educational Committee, and later during the first ECMI-HCM Project. While he was already very ill, he...
Article
Thanks to the development of information technologies, the last decade has seen a considerable growth of interest in the statistical theory of shape and its application to many and diverse scientific areas.
Chapter
Many processes of biomedical interest may be modeled as birth-and-growth processes (germ-grain models), which are composed of two processes, birth (nucleation, branching, etc.) and subsequent growth of spatial structures (cells, vessel networks, etc.), both of which, in general, are stochastic in time and space. These structures induce a random div...
Chapter
It has been shown by a substantial body of literature that the hazard function plays an important role in the derivation of evolution equations of volume and n-facet densities of Johnson-Mehl tessellations generated by germ-grain models associated with spatially homogeneous birth-and-growth processes. In this paper, we analyze a more general class...
Book
These proceedings are reporting on the conference "Math Everywhere", a successful event celebrating a leading scientist, promoting ideas he pursued and sharing the open atmosphere he is known for. The areas of the contributions are the following - Deterministic and Stochastic Systems. - Mathematical Problems in Biology, Medicine and Ecology. - Math...
Conference Paper
In this paper we introduce recent mathematical tools for shape description called size functions. Some features of these descriptors such as robustness with respect to noise are pointed out. A first attempt to join the theory of size functions with randomness and to develop the related statistical analysis is then presented. The resulting procedure...
Article
Full-text available
A collection of 66 poplar commercial clones widely cultivated in Italy, China and in other countries of southern Europe and belonging to various poplar species and hybrids, have been fingerprinted using both amplified fragment length polymorphism (AFLP) and simple sequence repeats (SSR) techniques. Three AFLP primer combinations and six SSRs unambi...
Chapter
Here some basic concepts of Statistical Shape Analysis are introduced and applied to a specific problem: automatic recognition and classification of cells coming from tumor tissues, from their nuclear profiles. The technique here described, which is commonly used for the description of the mean geometrical characteristics of families of random obje...
Article
Full-text available
Realistic crystal growth simulators can give information on what would be the surface structure of a crystal grown under specific physical-chemical con-ditions, avoiding the real growth in a laboratory. By suitable upscaling, simula-tions can therefore be useful for industrial purposes to foresee and control the final product. We initially present...
Article
This paper is devoted to the optimal design of polymeric materials through control of the cooling during the crystallization process. The optimality is defined in terms of optimal mechanical properties, which are directly related to the morphology of the solidified polymeric material. As a characterizing mathematical entity to be controlled the con...
Chapter
1 Introduction 2 Birth-and-Growth Processes 2.1 The germ process 2.2 Predictability 2.3 The compensator of a marked point process (MPP) 2.4 The geometric process of crystallization 2.5 The nucleation rate 3 Elements of Stochastic Geometry 3.1 Hit or miss topology 3.2 Random closed sets (RACSs) and hitting functional 4 Local Densities for...
Article
Polymer industry raises a large amount of relevant mathematical problems with respect to the quality of manufactured polymer parts. These include in particular questions about the crystallization kinetics of the polymer melt, in presence of a tem perature field.
Article
A Johnson-Mehl tessellation arises as a random division of a bounded region in a d-dimensional Euclidean space, generated by a stochastic birth-and-growth process, also known as a germ-grain process in stochastic geometry. The birth of germs is modelled as a stochastic spatially marked counting process (marked point process) with a space and time d...
Article
Crystallization of polymers is composed of two processes, nucleation (birth) and subsequent growth of crystallites, which are in general stochastic both in time and space. If we assume that at points of contact between two growing crystallites they stop growing, a random division of the relevant region in a d-dimensional space is obtained, known as...
Article
Polymer crystallization may be modelled by a stochastic birth-and-growth process, with temperature dependent parameters. The temperature field is itself stochastic, because of the release of latent heat, due to the phase change. A mathematical model which couples the evolution of crystal growth with the temperature field is here described. The fina...
Article
This paper is devoted to the numerical simulation of nonisothermal crystallization of polymers, which may be modelled as a stochastic birth-and-growth process. One of the main aims is to develop e- cient algorithms for the stochastic simulation of such process process. We put a special emphasis on the problem of computing the surface density of cry...
Article
In this paper we provide definitions for the local mean volume and mean surface densities of an inhomogeneous random closed set A theorem which relates the local spherical contact distribution function with the local surface and volume density is proven. Sufficient conditions on the regularity of the random set involved to satisfy the assumptions o...
Article
Crystallization of polymers is modelled as a spatially structured stochastic process consisting of a nucleation phase and a growth phase. A counting process approach together with methods of stochastic geometry lead us to the evolution equations for the relevant quantities of the process. Estimation of the relevant parameters of the process is obta...
Article
Gradient structures are inhomogeneous along a particular gradient direction but homogeneous perpendicular to that direction. Consequently, structural parameters such as volume fraction or surface area density are local characteristics which depend on the 'vertical' coordinate with respect to the 'vertical' gradient axis. Analogously, models for gra...
Article
A Johnson-Mehl tessellation arises as a random division of a given bounded region in a d-dimensional Euclidean space, generated by a stochastic birth-and-growth process, also known as a germ-grain process in stochastic geometry. A typical example is the crystallization of a polymer from an amorphous liquid phase by cooling; in this case a grain (cr...
Chapter
Crystallization of polymers is modelled as a spatially structured stochastic process consisting of a nucleation phase and a growth phase. A counting process approach together with methods of stochastic geometry lead us to the evolution equations of the relevant quantities of the process. Estimation of the relevant parameters of the process are obta...
Article
Crystallization of polymers is modelled as a spatially structured stochastic process consisting of a nucleation phase and a growth phase. A counting process approach together with methods of stochastic geometry leads us to the evolution equations of the relevant quantities of the process. In particular we provide local and global convergence of the...
Article
Isothermal crystallization of a polymer may be schematically described as a nucleation process followed by the growth of spherical crystals (spherulites) with both the nucleation rate N-0 and growth rate R(0) depending upon the specific temperature.
Article
Here a statistical method to estimate the intensity, or mean length density, of a fibre process is presented, based on a representation of the mean geometric densities of random closed sets, as expectations of random distributionsa la Dirac-Schwartz. The method extends the technique used when the probability density of a real valued random variable...
Article
We provide definitions for the local mean volume and mean surface densities of an inhomogeneous random closed set. A relation between the local spherical contact distribution function and the local surface density is proven. This relation is valid under a regularity condition on the random set involved, whose field of applicability is analysed in d...

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Project (1)
Project
In the near future the CAP will undergo through a process of change and restructuring, both for the need to revise and reform its policy instruments and to account for the outcomes of EU budget reshape. As a first step, the EU Commission is gathering stakeholders comments and suggestions on its document "Communication on Modernizing and Simplifying the CAP”, prefiguring five possible development options for the future CAP. In this context the CAPTION Project aims at contributing to such debate, providing scientific-based evidence on current impact of CAP and giving insights on innovative policy tools. Such kind of analysis is particularly relevant for examining and monitoring the new policy tools (greening payment) implemented in the current CAP programming period 2015-2020. Furthermore, the project provides possible alternatives with respect the current policy instruments in order to tackle the issues not properly covered by them.