Mixed-integer linearity in nonlinear optimization: a trust region approach

Bringing together nonlinear optimization with mixed-integer linear constraints enables versatile modeling, but poses significant computational challenges. We investigate a method to solve these problems based on sequential mixed-integer linearization with trust region safeguard, computing feasible iterates via calls to a generic mixed-integer linear solver. Convergence to critical, possibly suboptimal, feasible points is established for arbitrary starting points. Finally, we present numerical applications in nonsmooth optimal control and optimal network design and operation.Comment: 17 pages, 3 figures, 2 table

Proximal Gradient Methods Beyond Monotony

We address composite optimization problems, which consist in minimizing the sum of a smooth and a merely lower semicontinuous function, without any convexity assumptions. Numerical solutions of these problems can be obtained by proximal gradient methods, which often rely on a line search procedure as globalization mechanism. We consider an adaptive nonmonotone proximal gradient scheme based on an averaged merit function and establish asymptotic convergence guarantees under weak assumptions, delivering results on par with the monotone strategy. Finally, we derive global worst-case rates for the iterates and a stationarity measure.Comment: 16 pages, 1 algorith

Local properties and augmented Lagrangians in fully nonconvex composite optimization

A broad class of optimization problems can be cast in composite form, that is, considering the minimization of the composition of a lower semicontinuous function with a differentiable mapping. This paper discusses the versatile template of composite optimization without any convexity assumptions. First- and second-order optimality conditions are discussed, advancing the variational analysis of compositions. We highlight the difficulties that stem from the lack of convexity when dealing with necessary conditions in a Lagrangian framework and when considering error bounds. Building upon these characterizations, a local convergence analysis is delineated for a recently developed augmented Lagrangian method, deriving rates of convergence in the fully nonconvex setting.Comment: 42 page

Collision Avoidance using Iterative Dynamic and Nonlinear Programming with Adaptive Grid Refinements

Nonlinear optimal control problems for trajectory planning with obstacle avoidance present several challenges. While general-purpose optimizers and dynamic programming methods struggle when adopted separately, their combination enabled by a penalty approach was found capable of handling highly nonlinear systems while overcoming the curse of dimensionality. Nevertheless, using dynamic programming with a fixed state space discretization limits the set of reachable solutions, hindering convergence or requiring enormous memory resources for uniformly spaced grids. In this work we solve this issue by incorporating an adaptive refinement of the state space grid, splitting cells where needed to better capture the problem structure while requiring less discretization points overall. Numerical results on a space manipulator demonstrate the improved robustness and efficiency of the combined method with respect to the single components.Comment: Fixed typo in Reference [5

Self-Organised Schools

Self-Organised Schools: Educational Leadership and Innovative Learning Environments describes the results of the research we carried out at fourteen Italian schools that highlight how there is a positive correlation between the capabilities of school self-organization and the innovativeness of learning environments: in other words, the more self-organized schools are, the more innovative learning environments are. The results of this work are part of the strand of research of bottom-up emergency and self-organization, an extremely fruitful trend as shown by Sugata Mitra, the founder of the Self-Organized Learning Environments, according to whom, "education is a self-organized system where learning is an emerging phenomenon". This book gives new insights on self-organization studies, and most of all, to the idea that change - organizational and educational innovation - sparks from the bottom. This book is aimed specifically at school principals of all levels, scholastic reformers, educational scholars, organisation and management consultants who want to innovate learning and management of learning. These actors will benefit drawing useful examples from more than thirty different learning environments worldwide, fourteen examples of schools that self-organize, two frameworks - and two ready-to-use questionnaires - measuring the innovativeness of a learning environment, and the capability of a school to self-organize. Self-organization is the most fascinating future of innovative principal

Mild to moderate bleeding: diagnostic and therapeutic paths

We consider mild to moderate bleedings all bleeding events that do not meet the criteria proposed by the International Society of Thrombosis and Haemostasis (ISTH) for the definition of major bleeding. As regards the approach to the bleeding patient, the first step is undoubtedly an accurate collection of clinical history and overall physical examination. Then, the etiological diagnosis of a bleeding disorder uses a series of laboratory investigations, divided into first level tests, which are intended to identify the altered phase of the hemostatic process, and second level ones, i.e. more specific tests used if screening tests are negative or to better characterize the alteration identified by them. For the treatment of a bleeding disorder there are several approaches, all strictly dependent on the etiologic diagnosis of this disorder

Gestire o nascondere i conflitti socio-ambientali? La Social Licence to Operate nelle attività petrolifere dell’Amazzonia ecuadoriana

The main objective of this research was to critically examine the concept of Social Licence to Operate (SLO) in an oil concession of the Ecuadorian Amazon inhabited by indigenous villages. In this paper we present the qualitative data of the semi-structured interviews and the household survey with village residents. The main findings revealed the important role of the involvement of communities in the decision-making processes (procedural fairness), people’s perceptions of company’s socio-environmental impacts, the management of forms of protest and social services in the communities. Particularly, the results suggested that procedural fairness and the respect of communities’ right of self-determination are the basic requisite for the application of the SLO concept in the study area

Cluster-based Vibration Analysis of Structures with GSP

This article describes a divide-and-conquer strategy suited for vibration monitoring applications. Based on a low-cost embedded network of microelectromechanical accelerometers, the proposed architecture strives to reduce both power consumption and computational resources. Moreover, it eases the sensor deployment on large structures by exploiting a novel clustering scheme, which consists of unconventional and nonoverlapped sensing configurations. Signal processing techniques for inter- and intracluster data assembly are introduced to allow for a fullscale assessment of the structural integrity. More specifically, the capability of graph signal processing is adopted for the first time in vibration-based monitoring scenarios to capture the spatial relationship between acceleration data. The experimental validation, conducted on a steel beam perturbed with additive mass, reveals high accuracy in damage detection tasks. Deviations in spectral content and mode shape envelopes are correctly revealed regardless of environmental factors and operational uncertainties. Furthermore, an additional key advantage of the implemented architecture relies on its compliance with blind modal investigations, an approach that favors the implementation of autonomous smart monitoring systems

Formazione per il futuro: spunti di riflessione per il settore edile-artigianoA

Nota derivante dal lavoro svolto per il Progetto di ricerca Monitoraggio della formazione in materia di sicurezza e rilevazione delle competenze richieste, promosso da Edilcassa Veneto e svolto da Ires Veneto, consistente in focus group compiuto con le parti sociali

Synthesis of liquid menthol by hydrogenation of dementholized peppermint oil over Ni catalysts

Hydrogenation of (-)-menthone and (+)-isomenthone was studied at 2.7 MPa and 100 ºC. The objective was to produce a liquid menthol mixture rich in (-)-menthol from dementholized peppermint oil. Ni-based catalysts were tested and compared for this reaction: a) 6 and 12% Ni dispersed into a nonstoichiometric magnesium aluminate (Ni-Mg-Al) with spinel structure; b) Ni-Raney catalyst. Both types of catalysts were active for (-)-menthone and (+)-isomenthone hydrogenation. Lower conversion but higher selectivity to (-)-menthol was obtained with Ni-Mg-Al catalysts. However, they rapidly lost their activity. Instead Ni-Raney catalysts kept its original activity even after several hydrogenation runs