Search results for " Computer Science"
showing 10 items of 3983 documents
Mathematical models for Multi Container Loading Problems with practical constraints
2019
Abstract We address the multi container loading problem of a company that serves its customers’ orders by building pallets with the required products and loading them into trucks. The problem is solved by using integer linear models. To be useful in practice, our models consider three types of constraints: geometric constraints, so that pallets lie completely inside the trucks and do not overlap; weight constraints, defining the maximum weights supported by a truck and by each axle, as well as the position of the centre of gravity of the cargo; and dynamic stability constraints. These last constraints forbid empty spaces between pallets to avoid cargo displacement when the truck is moving, …
The Multi-period Multi-trip Container Drayage Problem with Release and Due Dates
2021
Abstract The Container Drayage Problem (CDP) aims at routing a fleet of trucks, based at a common terminal, to serve customers while minimizing the total travel distance. Each trip starts from and ends at the terminal, and handles a subset of customers. Each customer requires either that a container is picked up or delivered. We introduce a more realistic variant, i.e., the Multi-trip Multi-period CDP with Release and Due Dates (MM-CDP-RDD), in which the planning horizon is composed of several periods (days). On each day, each truck may perform more than one trip respecting the Release and Due Dates (RDD) associated with customer services, corresponding to the first and the last day on whic…
High-accuracy approximation of piecewise smooth functions using the Truncation and Encode approach
2017
Abstract In the present work, we analyze a technique designed by Geraci et al. in [1,11] named the Truncate and Encode (TE) strategy. It was presented as a non-intrusive method for steady and non-steady Partial Differential Equations (PDEs) in Uncertainty Quantification (UQ), and as a weakly intrusive method in the unsteady case. We analyze the TE algorithm applied to the approximation of functions, and in particular its performance for piecewise smooth functions. We carry out some numerical experiments, comparing the performance of the algorithm when using different linear and non-linear interpolation techniques and provide some recommendations that we find useful in order to achieve a hig…
Singular Neumann (p, q)-equations
2019
We consider a nonlinear parametric Neumann problem driven by the sum of a p-Laplacian and of a q-Laplacian and exhibiting in the reaction the competing effects of a singular term and of a resonant term. Using variational methods together with suitable truncation and comparison techniques, we show that for small values of the parameter the problem has at least two positive smooth solutions.
IoT-MAAC: Multiple Attribute Access Control for IoT environments
2020
Access Control is an important security service that should be considered in IoT environments in order to offer reliable IoT services. Access control in IoT environments concerns not only the access of IoT users to IoT services and objects, but also the access of IoT objects to IoT gateways. In this paper, we specify an access control mechanism that considers the access of IoT objects to IoT gateways in order to enhance the reliability of IoT data provided by the IoT objects. Our proposed access control mechanism, called IoT-MAAC (Multi Attribute Access Control), allows retrieving requested data from the most reliable and secured IoT objects among the available objects in the IoT environmen…
18F-FDG PET for breast cancer : combined analysis of tumour perfusion and metabolism for tumour characterisation and neoadjuvant chemotherapy respons…
2020
Neoadjuvant chemotherapy (NAC) is a common treatment in patients with locally advanced or large breast cancer at diagnosis. A pathological complete response (pCR) at the end of NAC is recognized as a good surrogate marker of relapse-free survival. An early identification of the pathological response has then become a key parameter to monitor new therapeutic strategies. Studies, focusing on predictive biomarkers identification, have shown that early changes in tumour metabolism, assessed by Positron Emission Tomography (PET) using 2-desoxy-2-18F-fluoro-D-glucose (18F-FDG), allow the early assessment of the pathological response at the end of treatment. However, given the diversity of breast …
Logic, Computing and Biology
2015
Logic and Computing are appropriate formal languages for Biology, and we may well be surprised by the strong analogy between software and DNA, and between hardware and the protein machinery of the cell. This chapter examines to what extent any biological entity can be described by an algorithm and, therefore, whether the Turing machine and the halting problem concepts apply. Last of all, I introduce the concepts of recursion and algorithmic complexity, both from the field of computer science, which can help us understand and conceptualise biological complexity.
Inductive inference of recursive functions: Qualitative theory
2005
This survey contains both old and very recent results in non-quantitative aspects of inductive inference of total recursive functions. The survey is not complete. The paper was written to stress some of the main results in selected directions of research performed at the University of Latvia rather than to exhaust all of the obtained results. We concentrated on the more explored areas such as the inference of indices in non-Goedel computable numberings, the inference of minimal Goedel numbers, and the specifics of inference of minimal indices in Kolmogorov numberings.
Transformations Between UML Diagrams
2003
The Unified Modeling Language (UML) provides various diagram types for describing a system from different perspectives or abstraction levels. Hence, UML diagrams describing the same system are dependent and strongly overlapping. In this paper we study how this can be exploited for specifying transformation operations between different diagram types. We discuss various general approaches and viewpoints of model transformations in UML. The source and target diagram types for useful transformations are analyzed and given categories. The potentially most interesting transformation operations are discussed in detail. It is concluded that the transformation operations can automate a substantial p…
Reduction of UML Class Diagrams
2002
One and the same “real world” can be modeled by different UML class diagrams, which in such a case can be considered “intuitively equivalent”. A formalization of this “intuitive equivalence” of class diagrams is proposed. An algorithm is constructed that for two class diagrams determines if they model the same “real world”. This algorithm can be used in CASE tools to compare alternative models of a system, and for diagram “compression” to facilitate understanding of large diagrams.