84 research outputs found
Advanced manufacturing techniques for X-ray and VHE gamma-ray astronomical mirrors.
No full textThe main theme of this thesis is on the development of the technologies for the future X-ray astronomy telescopes and specifically for the New Hard X-ray Mission and eROSITA (Spectrum-RG) missions. Other important next future X-ray missions, currently under advanced study and/or manufacturing are NuSTAR (USA), ASTRO-H (Japan) and GEMS (USA).
The New Hard X-ray Mission (NHXM) is being developed in Italy as an evolution of the original HEXIT-SAT project and is now the hard x-ray project of reference for the Italian high energy community. NHXM is meant to provide a real breakthrough on a number of hot astrophysical issues, by exploiting the most advanced technology in broad-band (0.2 – 80 keV) high angular resolution (<20 arc seconds HEW) grazing incidence mirrors and spectroscopic detectors, together with the use of a high efficiency imaging polarimeter. Such issues can be summarized in two main headings:
● making the census of the population of black holes in the Universe and probing the physics of accretion in the most diverse conditions;
● investigating the particle acceleration mechanisms at work in different contexts, and the effects of radiative transfer in highly magnetized plasmas and strong gravitational fields.
These topics were identified as top priority in the study commissioned by the Italian Space Agency (ASI) in 2004 to the Italian scientific community with contracts involving Thales-Alenia Space Italy (TAS-I, Turin), the Media Lario Technologies (MLT, Lecco) company and the INAF institution. NHXM benefits from the phase A study of the canceled French-Italian-German SIMBOL-X mission (2007-2008) and has been recently subjected to a scientific phase B study financed by ASI. Media Lario Technologies company received a contract from ASI in 2009 for a Technology Development Program (ASI-TDP) aiming at improving the technology readiness level with also in-house adoption of hardware for the metrology/manufacturing of the multilayer x-ray optics.
Spectrum-RG is a Russian - German x-ray astrophysical observatory scheduled for lunch in 2013. German Space Agency (DLR) is responsible for the development of the key mission instrument - the x-ray grazing incident mirror telescope eROSITA. The second experiment is ART-XC - an x-ray mirror telescope with a harder response than eROSITA, which is being developed by Russia (IKI, Moscow and VNIIEF, Sarov). The name eROSITA stands for extended Roentgen Survey with an Imaging Telescope Array. The general design of the eROSITA x-ray telescope is derived from that of ABRIXAS: a bundle of 7 mirror modules with short focal lengths make up a compact telescope which is ideal for survey observations. Similar designs had been proposed for the missions DUO and ROSITA but were not realized. Compared to those, however, the effective area in the soft x-ray band has now much increased by adding 27 additional outer mirror shells to the original 27 ones of each mirror module. The requirement on the on-axis resolution has also been confined, namely to 15 arc seconds HEW. For these reasons the prefix “extended” to the original name “ROSITA” had been added. The scientific motivation for this extension is founded in the ambitious goal to detect about 100000 clusters of galaxies which trace the large scale structure of the Universe in space and time.
The main scientific goals are:
● to detect the hot intergalactic medium of 50-100 thousand galaxy clusters and groups and hot gas in filaments between clusters to map out the large scale structure in the Universe for the study of cosmic structure evolution;
● to detect systematically all obscured accreting Black Holes in nearby galaxies and many (up to 3 Million) new, distant active galactic nuclei;
● to study in detail the physics of galactic x-ray source populations, like pre-main sequence stars, supernova remnants and x-ray binaries.
Max-Planck-Institute für extraterrestrische Physik (MPE) is the scientific institute responsible for the eROSITA Payload. Media Lario Technologies (MLT) is the industrial enabler for the manufacturing of the Optical Payload for eROSITA - including the flight quality mandrels, and it is currently in the C/D Phase of the project.
The research activity described in this thesis has been carried out at Media Lario Technologies company and at the Brera Astronomical Observatory under the supervision of INAF-OAB researchers Dott. Giovanni Pareschi and Dott. Gianpiero Tagliaferri. The research activity of the author of this thesis is focused on the development of an advance polishing technique for the mandrels to be used as masters in the mirrors replication by electroforming. The goal is to implement a process where the mandrels can be manufactured with a high accuracy (< 6 arc seconds HEW) and low roughness (< 0.2 nm rms) within a consistent short time. In the contest of the eROSITA and NHXM (projects currently running in MLT) the author participated as technical/scientific responsible, investigating innovative mandrels manufacturing technologies (e.g. Single Point Diamond Turning, shape corrective polishing) representing an evolution of the standard approach used so far. In this frame the author has also contributed to the adoption of a customized deterministic polishing machine and a customized 3D metrology device for the mandrel geometrical characterization.
An additional research activity, performed by the author at Media Lario Technologies company and at the Brera Astronomical Observatory, is focused on the development of lightweight glass mirrors manufactured via cold-slumping technique for Imaging Atmospheric Cherenkov Telescopes (IACT). Very High Energy (VHE) gamma rays, with photon energies in the TeV range, can be detected by ground based experiments. In fact, such high energy photons interact high in the upper atmosphere and generate an air shower of secondary particles. These particles emit the so-called Cherenkov light, a faint blue light. The mirror elements here developed have a sandwich-like structure where the reflecting and backing facets are composed by glass sheets with an interposed honeycomb aluminum core. This effort found application at the world’s largest IACT, the 17m MAGIC II telescope (currently operating in Roque de los Muchachos - La Palma, Canary Islands), where 112 mirrors (~ 1 squared meter each), manufactured with the newly developed cold-slumping technique here described, are installed
Quick Combinatorial Artificial Bee Colony -qCABC- Optimization Algorithm for TSP
No full textCombinatorial Artificial Bee Colony Algorithm (CABC) is a new version of Artificial Bee Colony (ABC) to solve combinatorial type optimization problems and quick Artificial Bee Colony (qABC) algorithm is an improved version of ABC in which the onlooker bees behavior is modeled in more detailed way. Studies showed that qABC algorithm improves the convergence performance of standard ABC on numerical optimization. In this paper, to see the performance of this new modeling way of onlookers' behavior on combinatorial optimization, we apply the qABC idea to CABC and name this new algorithm as quick CABC (qCABC). qCABC is tested on Traveling Salesman Problem and simulation results show that qCABC algorithm improves the convergence and final performance of CABC
Artificial Bee Colony (ABC) Optimization Algorithm for Solving Constrained Optimization Problems
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Performance analysis of artificial bee colony algorithm on ARM based mobile platform
No full text2017 International Conference on Computer Science and Engineering (UBMK) -- OCT 05-08, 2017 -- Antalya, TURKEYAKSOY, Alperen/0000-0002-8935-7369; Karaboga, Dervis/0000-0003-1439-6969Improved mobile devices have the computational power and software support for processing complex algorithmic expressions with the similar execution time when compared to the conventional processors. In this study, we investigated both serial and parallel implementations of Artificial Bee Colony (ABC) algorithm that is one of the most important swarm intelligence based algorithms by solving different types of numerical problems on a mobile platform. Experimental studies showed that serial and parallel implementations of ABC algorithm are suitable for execution on mobile processors and there is a correspondence between the final solutions obtained by ABC algorithm on a mobile processor and the final solutions obtained by ABC algorithm on a conventional processor.IEEE Adv Technol Human, Istanbul Teknik Univ, Gazi Univ, Atilim Univ, TBV, Akdeniz Univ, Tmmob Bilgisayar Muhendisleri Odas
Implementation of Artificial Bee Colony Algorithm
No full textEvolutionary algorithm is a stochastic search method that mimics the natural biological evolution and the social behavior of species. Artificial bee colony algorithm is also a kind of evolutionary algorithm which was proposed by Dervis karaboga in 2005.Such algorithms have been developed to arrive at near-optimum solutions of multimodal optimization problems, which may not be possible with traditional algorithms. This paper describes implementation of ABC algorithm on complex benchmark functions like rastrigin, rosenbrock; sphere and schwefel the analysis of the performance of ABC algorithm were compared for the optimization of above benchmark functions with Partical Swarm Optimization (PSO). The ABC algorithm was successfully implemented in software tool ‘c’.DOI: http://dx.doi.org/10.11591/ij-ai.v1i3.58
Training recurrent neural networks by using parallel tabu search algorithm based on crossover operation
No full textThere are several heuristic optimisation techniques used for numeric optimisation problems such as genetic algorithms, neural networks, simulated annealing, ant colony and tabu search algorithms. Tabu search is a quite promising search technique for non-linear numeric problems, especially for the problems where an optimal solution must be determined on-line. However, the converging speed of the basic tabu search to the global optimum is the initial solution dependent since it is a form of iterative search. In order to overcome this drawback of basic tabu search, this paper proposes a new parallel model for the tabu search based on the crossover operator of genetic algorithms. After the performance of the proposed model was evaluated for the well-known numeric test problems, it is applied to training recurrent neural networks to identify linear and non-linear dynamic plants and the results are discussed. (C) 2004 Elsevier Ltd. All rights reserved
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