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Budapest, Hungary

The Budapest University of Technology and Economics , in Hungarian abbreviated as BME, English official abbreviation BME, is the most significant University of Technology in Hungary and is also the oldest Institute of Technology in the world, having been founded in 1782. Wikipedia.

Rozvany G.I.N.,Budapest University of Technology and Economics
Structural and Multidisciplinary Optimization | Year: 2011

The aim of this article is to initiate an exchange of ideas on symmetry and non-uniqueness in topology optimization. These concepts are discussed in the context of 2D trusses and grillages, but could be extended to other structures and design constraints, including 3D problems and numerical solutions. The treatment of the subject is pitched at the background of engineering researchers, and principles of mechanics are given preference to those of pure mathematics. The author hopes to provide some new insights into fundamental properties of exact optimal topologies. Combining elements of the optimal layout theory (of Prager and the author) with those of linear programming, it is concluded that for the considered problems the optimal topology is in general unique and symmetric if the loads, domain boundaries and supports are symmetric. However, in some special cases the number of optimal solutions may be infinite, and some of these may be non-symmetric. The deeper reasons for the above findings are explained in the light of the above layout theory. © Springer-Verlag 2010. Source

Insperger T.,Budapest University of Technology and Economics
International Journal of Machine Tools and Manufacture | Year: 2010

The full-discretization method recently proposed by Ding et al. (2010) [1] for the stability analysis of milling processes is shown to be related to the semi-discretization method in the sense that both methods approximate the original DDE by a series of ODEs. Rate of convergence estimates are provided for the full-discretization method, for the zeroth-order, and for the first-order semi-discretization methods. Computation times are analyzed and compared for low and high spindle speed domains. © 2010 Elsevier Ltd. All rights reserved. Source

Nagy A.,Budapest University of Technology and Economics
Annals of Physics | Year: 2012

We construct an algorithm to simulate imaginary time evolution of translationally invariant spin systems with local interactions on an infinite, symmetric tree. We describe the state by symmetric infinite-Tree Tensor Network (iTTN) and use translation-invariant operators for the updates at each time step. The contraction of this tree tensor network can be computed efficiently by recursion without approximations and one can then truncate all the iTTN tensors at the same time. The translational symmetry is preserved at each time step that makes the algorithm very well conditioned and stable. The computational cost scales like O(D q+1) with the bond dimension D and coordination number q, much favorable than that of the iTEBD on trees [D. Nagaj, E. Farhi, J. Goldstone, P. Shor, I. Sylvester, Phys. Rev. B 77 (2008) 214431]. Studying the transverse-field Ising model on the Bethe lattice, the numerics indicate a ferromagnetic-paramagnetic phase transition, with a finite correlation length even at the transition point. © 2011 Elsevier Inc. Source

Modla G.,Budapest University of Technology and Economics
Energy | Year: 2013

In this work two energy saving methods are presented for the separation of a minimum boiling point azeotrope by using an intermediate entrainer. Extractive distillation column configurations with conventional, thermally integrated and dividing-wall columns are used for comparison. These configurations are designed, rigorously simulated and optimized to minimize the Total Annual Cost and to reduce the energy requirement. A novel simple method is proposed based on a Genetic Algorithm to determine the main design and operation parameters of the dividing-wall column. The optimization algorithm is written in Excel Macro interconnected with the ChemCad process flow-sheet simulator. In terms of total annual costs, the extractive dividing-wall column was found to be the most economical scheme, followed by the thermally integrated and conventional extractive distillation methods. © 2012 Elsevier Ltd. Source

Van Do T.V.,Budapest University of Technology and Economics
Computers and Operations Research | Year: 2010

The Dynamic Host Configuration Protocol (DHCP) is designed to provide an automatic mechanism for the allocation, configuration and management of IP addresses and TCP/IP protocol stack parameters of computers and devices in IP networks. The important feature of DHCP is a "dynamic allocation" mechanism, which assigns an IP address to a client for a limited period of time (called a lease time). Therefore, a previously allocated IP address can automatically be assigned to another host by a DHCP server upon the expiration of the lease time if a host does not renew the use of an allocated IP address. This paper proposes a retrial queueing model to approximate the performability of the DHCP dynamic allocation mechanism. An efficient computational algorithm is developed to calculate the steady state probabilities of a continuous time discrete state Markov process. A comparison of our approximate model with a detailed simulation model of the DHCP dynamic allocation mechanism shows an excellent agreement between the analytical and the simulation results. The impact of the lease time parameter on the performability of the DHCP dynamic allocation mechanism is also illustrated through a numerical study. © 2009 Elsevier Ltd. All rights reserved. Source

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