| 1. |
- Kruschwitz, Jens, et al.
(författare)
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Modelling, simulation and parameter identification of active pollution reduction with photocatalytic asphalt
- 2019
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Ingår i: Acta Polytechnica. - Prague : Czech Technical University in Prague. - 1210-2709 .- 1805-2363. ; 59:1, s. 51-58
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Tidskriftsartikel (refereegranskat)abstract
- We develop and implement a numerical model to simulate the effect of photocatalytic asphalt on reducing the concentration of nitrogen monoxide (NO) due to the presence of heavy traffic in an urban environment. The contributions in this paper are threefold: we model and simulate the spread and breakdown of pollution in an urban environment, we provide a parameter estimation process that can be used to find missing parameters, and finally, we train and compare this simulation with different data sets. We analyse the results and provide an outlook on further research.
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| 2. |
- Mansouri, Masoumeh, 1985-, et al.
(författare)
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Hybrid Reasoning for Multi-robot Drill Planning in Open-pit Mines
- 2016
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Ingår i: Acta Polytechnica. - Prague, Czech Republic : Czech Technical University in Prague. - 1210-2709 .- 1805-2363. ; 56:1, s. 47-56
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Tidskriftsartikel (refereegranskat)abstract
- Fleet automation often involves solving several strongly correlated sub-problems, including task allocation, motion planning, and coordination. Solutions need to account for very specific, domaindependent constraints. In addition, several aspects of the overall fleet management problem become known only online. We propose a method for solving the fleet-management problem grounded on a heuristically-guided search in the space of mutually feasible solutions to sub-problems. We focus on a mining application which requires online contingency handling and accommodating many domainspecific constraints. As contingencies occur, efficient reasoning is performed to adjust the plan online for the entire fleet.
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| 3. |
- Mickelsson, Jouko
(författare)
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From Gauge Anomalies to Gerbes and Gerbal Representations : Group Cocycles in Quantum Theory
- 2010
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Ingår i: Acta Polytechnica: Journal of Advanced Engineering. - : Czech Technical University in Prague - Central Library. - 1210-2709 .- 1805-2363. ; 50:3, s. 42-47
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Tidskriftsartikel (refereegranskat)abstract
- In this paper I shall discuss the role of group cohomology in quantum mechanics and quantum field theory. First, I recall how cocycles of degree 1 and 2 appear naturally in the context of gauge anomalies. Then we investigate how group cohomology of degree 3 comes from a prolongation problem for group extensions and we discuss its role in quantum field theory. Finally, we discuss a generalization to representation theory where a representation is replaced by a 1-cocycle or its prolongation by a circle, and point out how this type of situations come up in the quantization of Yang-Mills theory.
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| 4. |
- Stolin, Alexander, 1953
(författare)
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25 Years of Quantum Groups: from Definition to Classification
- 2008
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Ingår i: Acta Polytechnica. - 1210-2709 .- 1805-2363. ; 48:2, s. 25-28
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In mathematics and theoretical physics, quantum groups are certain non-commutative, non-cocommutative Hopf algebras, which first appeared in the theory of quantum integrable models and later they were formalized by Drinfeld and Jimbo. In this paper we present a classification scheme for quantum groups, whose classical limit is a polynomial Lie algebra. As a consequence we obtain deformed XXX and XXZ Hamiltonians.
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| 5. |
- Bruno, A., et al.
(författare)
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Precise cosmic rays measurements with PAMELA
- 2013
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Ingår i: Acta Polytechnica. - 1210-2709. ; 53:Suppl.1, s. 712-717
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Tidskriftsartikel (refereegranskat)abstract
- The PAMELA experiment was launched on board the Resurs-DK1 satellite on June 15th 2006. The apparatus was designed to conduct precision studies of charged cosmic radiation over a wide energy range, from tens of MeV up to several hundred GeV, with unprecedented statistics. In five years of continuous data taking in space, PAMELA accurately measured the energy spectra of cosmic ray antiprotons and positrons, as well as protons, electrons and light nuclei, sometimes providing data in unexplored energetic regions. These important results have shed new light in several astrophysical fields like: an indirect search for Dark Matter, a search for cosmological antimatter (anti-Helium), and the validation of acceleration, transport and secondary production models of cosmic rays in the Galaxy. Some of the most important items of Solar and Magnetospheric physics were also investigated. Here we present the most recent results obtained by the PAMELA experiment.
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| 6. |
- Karas, V., et al.
(författare)
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Distinguishing between spot and torus models of high-frequency quasiperiodic oscillations
- 2014
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Ingår i: Acta Polytechnica. - : Czech Technical University. - 1210-2709. ; 54:3, s. 191-196
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Tidskriftsartikel (refereegranskat)abstract
- In the context of high-frequency quasi-periodic oscillation (HF QPOs) we further explore the appearance of an observable signal generated by hot spots moving along quasi-elliptic trajectories close to the innermost stable circular orbit in the Schwarzschild spacetime. The aim of our investigation is to reveal whether observable characteristics of the Fourier power-spectral density can help us to distinguish between the two competing models, namely, the idea of bright spots orbiting on the surface of an accretion torus versus the scenario of intrinsic oscillations of the torus itself. We take the capabilities of the present observatories (represented by the Rossi X-ray Timing Explorer, RXTE) into account, and we also consider the proposed future instruments (represented here by the Large Observatory for X-ray Timing, LOFT). © Czech Technical University in Prague, 2014.
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| 7. |
- Lindh, Per, et al.
(författare)
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UTILISING PARETO EFFICIENCY AND RSM TO ADJUST BINDER CONTENT IN CLAY STABILISATION FOR YTTRE RINGVÄGEN, MALMÖ
- 2023
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Ingår i: Acta Polytechnica. - 1210-2709. ; 63:2, s. 140-157
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a new framework for improving soil strength using an advanced method of engineering statistics. The materials included clay till collected in Yttre Ringvägen, southern Sweden. Binders included quicklime, slag and ordinary Portland cement used as pure binders and blended mixtures. We first applied the Response Surface Methodology techniques aimed at binder blend optimisation: 1) Central Composite Design; 2) Box-Behnken Design; 3) Simplex Lattice Design. The Pareto charts were presented for modelling responses from tests with different binders and estimating their effects on soil strength. Finally, to examine the variables important for soil stabilisation, we also evaluated the effect of the amount of binder and the interaction between cement/lime/slag in different ratios: 30-50-20 %; 50-50-0 %; 100-0-0 % The paper highlights the major opportunities and challenges of engineering statistics as a cross-cutting research direction for the issues of civil engineering.
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| 8. |
- Pohl, J, et al.
(författare)
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Conceptual Design of a Hydraulic Valve Train System
- 2001
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Ingår i: Acta Polytechnica - Czech Technical University in Prague. - 1210-2709. ; 41:4/5, s. 20-28
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Tidskriftsartikel (refereegranskat)abstract
- Variable valve train systems have been brought into focus during recent years as a means to decrease fuel consumption in tomorrow’s combustion engines. In this paper an integrated approach, called simulation driven experiments, is utilised in order to aid the development of such highly dynamic systems. Through the use of systematic design methodology, a number of feasible concepts are developed. Critical components are subsequently identified using simulation. In this approach, component behaviour is simulated and validated by measurements on prototype components. These models are unified with complete system models of hydraulically actuated valve trains. In the case of the valve trains systems studied here component models could be validated using comparably simple test set-ups. These models enable the determination of non-critical design parameters in an optimal sense. This results in a number of optimised concepts facilitating an impartial functional concept selection.
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| 9. |
- Shapiro, Boris, et al.
(författare)
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Polynomial solutions of the Heun equation
- 2011
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Ingår i: Acta Polytechnica. - 1805-2363. ; 51:4, s. 90-94
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Tidskriftsartikel (refereegranskat)abstract
- We review properties of certain types of polynomial solutions of theHeun equation. Two aspects are particularly concerned, the inter-lacing property of spectral and Stieltjes polynomials in the case ofreal roots of these polynomials and asymptotic root distribution whencomplex roots are present.
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| 10. |
- Wen, Wei, et al.
(författare)
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Back to basics : Towards novel computation and arrangement of spatial sensory in images
- 2016
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Ingår i: Acta Polytechnica. - : CZECH TECHNICAL UNIV PRAGUE. - 1210-2709. ; 56:5, s. 409-416
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Tidskriftsartikel (refereegranskat)abstract
- The current camera has made a huge progress in the sensor resolution and the low-luminance performance. However, we are still far from having an optimal camera as powerful as our eye is. The study of the evolution process of our visual system indicates attention to two major issues: the form and the density of the sensor. High contrast and optimal sampling properties of our visual spatial arrangement are related directly to the densely hexagonal form. In this paper, we propose a novel software-based method to create images on a compact dense hexagonal grid, derived from a simulated square sensor array by a virtual increase of the fill factor and a half a pixel shifting. After that, the orbit functions are proposed for a hexagonal image processing. The results show it is possible to achieve image processing operations in the orbit domain and the generated hexagonal images are superior, in detection of curvature edges, to the square images. We believe that the orbit domain image processing has a great potential to be the standard processing for hexagonal images.
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