Search results for "TRACT"
showing 10 items of 9251 documents
GRASP and tabu search for the generalized dispersion problem
2021
Abstract The problem of maximizing dispersion requires the selection of a specific number of elements from a given set, in such a way that the minimum distance between the pairs of selected elements is maximized. In recent years, this problem has received a lot of attention and has been solved with many complex heuristics. However, there is a recent variant in which the selected elements have to satisfy two realistic constraints, a minimum capacity limit and a maximum budget, which in spite of its practical significance in facility location, has received little attention. In this paper, we first propose mathematical models to obtain the optimal solution of small- and medium-size instances, …
JOINT TOPOLOGY LEARNING AND GRAPH SIGNAL RECOVERY VIA KALMAN FILTER IN CAUSAL DATA PROCESSES
2018
In this paper, a joint graph-signal recovery approach is investigated when we have a set of noisy graph signals generated based on a causal graph process. By leveraging the Kalman filter framework, a three steps iterative algorithm is utilized to predict and update signal estimation as well as graph topology learning, called Topological Kalman Filter or TKF. Similar to the regular Kalman filter, we first predict the a posterior signal state based on the prior available data and then this prediction is updated and corrected based on the recently arrived measurement. But contrary to the conventional Kalman filter algorithm, we have no information of the transition matrix and hence we relate t…
Algorithmic Approach for Slot Filling Factors Determination in Electrical Machines
2018
In several industrial sectors, such as electric and hybrid traction, the demand for increasingly efficient and high power density electrical machines has grown considerably over the last few years. The improvement of slot filling factor of the electrical machines is an useful provision to satisfy this request. In particular, this topic has been the subject of interest for the industrial sector in recent years, since the technology of winding processes have evolved and allow an economically sustainable realization of windings with an ordered structure rather than randomly. The winding phase must be supported by an accurate design process in which it is possible to evaluate the maximum slot f…
Leveraging Partnerships with Logistics Service Providers in Humanitarian Supply Chains by Blockchain-based Smart Contracts
2019
As humanitarian organizations are struggling to reach an increasing number of beneficiaries, humanitarian-business partnerships, such as the use of logistics service providers (LSPs), promise to improve effectivity and efficiency of humanitarian assistance. Blockchain-based smart contracts which ensure automation, transparency, and efficiency promise to facilitate partnerships, particularly if trust is low. In this paper, blockchain-based smart contracts are critically examined for their application to humanitarian supply chains (HSCs). We identify various adoption barriers which we categorize into organizational, technological, and environmental. As the use of blockchain-based smart contra…
Buckling and post-buckling analysis of cracked stiffened panels via an X-Ritz method
2019
Abstract A multi-domain eXtended Ritz formulation, called X-Ritz, for the analysis of buckling and post-buckling of stiffened panels with cracks is presented. The theoretical framework is based on the First-order Shear Deformation Theory and accounts for von Karman's geometric nonlinearities. The structure is modeled as assembly of plate elements. Penalty techniques are used to fulfill the continuity condition along the edges of contiguous elements and to satisfy essential boundary conditions requirements. The use of an extended set of approximating functions allows to model through-the-thickness cracks and to capture the crack opening and tip singular fields as well as the structural behav…
Integrated WAAM-Subtractive Versus Pure Subtractive Manufacturing Approaches: An Energy Efficiency Comparison
2019
Over the last years, additive manufacturing (AM) has been gathering momentum both in the academic and in the industrial world. Besides the obvious benefits in terms of flexibility and process capabilities, the environmental performance of such processes has still to be properly analyzed. Actually, the advantages of additive manufacturing over conventional processes are not obvious. Indeed, different manufacturing approaches result in different amounts of involved material and in different processing energy demands. Environmental comparative analyses are hence crucial to properly characterize AM processes. In this paper, an energetic comparison between the emerging wire arc additive manufact…
Iterated greedy with variable neighborhood search for a multiobjective waste collection problem
2020
Abstract In the last few years, the application of decision making to logistic problems has become crucial for public and private organizations. Efficient decisions clearly contribute to improve operational aspects such as cost reduction or service improvement. The particular case of waste collection service considered in this paper involves a set of economic, labor and environmental issues that translate into difficult operational problems. They pose a challenge to nowadays optimization technologies since they have multiple constraints and multiple objectives that may be in conflict. We therefore need to resort to multiobjective approaches to model and solve this problem, providing efficie…
Networked Bio-Inspired Evolutionary Dynamics on a Multi-Population
2019
We consider a multi-population, represented by a network of groups of individuals. Every player of each group can choose between two options, and we study the problem of reaching consensus. The dynamics not only depend on the dynamics within the group, but they also depend on the topology of the network, so neighboring groups influence individuals as well. First, we develop a mathematical model of this networked bio-inspired evolutionary behavior and we study its steady-state. We look at the special case where the underlying network topology is a regular and unweighted graph and show that the steady-state is a consensus equilibrium. A sufficient condition for exponential stability is given.…
Graph-theoretical derivation of brain structural connectivity
2020
Brain connectivity at the single neuron level can provide fundamental insights into how information is integrated and propagated within and between brain regions. However, it is almost impossible to adequately study this problem experimentally and, despite intense efforts in the field, no mathematical description has been obtained so far. Here, we present a mathematical framework based on a graph-theoretical approach that, starting from experimental data obtained from a few small subsets of neurons, can quantitatively explain and predict the corresponding full network properties. This model also changes the paradigm with which large-scale model networks can be built, from using probabilisti…
Types of Mimetics for the Design of Intelligent Technologies
2019
Mimetic design means using a source in the natural or artificial worlds as an inspiration for technological solutions. It is based around the abstraction of the relevant operating principles in a source domain. This means that one must be able to identify the correct level of analysis and extract the relevant patterns. How this should be done is based on the type of source. From a mimetic perspective, if the design goal is intelligent technology, an obvious source of inspiration is human information processing, which we have called cognitive mimetics. This article offers some conceptual clarification on the nature of cognitive mimetics by contrasting it with biomimetics in the context of in…