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Search Results: 1 - 10 of 4350 matches for " Sebastian Rulik "
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Numerical Modelling of Aerodynamic Noise in Compressible Flows  [PDF]
S?awomir Dykas, Sebastian Rulik, W?odzimierz Wroblewski
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.23007
Abstract: The solution of the AeroAcoustics (CAA) problems by means of the Direct Numerical Simulation (DNS) or even the Large Eddy Simulation (LES) for a large computational domain is very time consuming and cannot be applied widely for engineering applications. In this paper the in-house CFD and CAA codes are presented. The in-house CFD code is based on the LES approach whereas the CAA code is an acoustic postprocessor solving the non-linearized Euler equations for fluctuating (acoustic) variables. These codes are used to solve the aerodynamically generated sound field by a flow over a rectangular cavity with inlet Mach number 0.53.
Numerical Method for Modeling of Acoustic Waves Propagation
S awomir Dykas , W odzimierz Wróblewski , Sebastian Rulik , Tadeusz Chmielniak
Archives of Acoustics , 2010, DOI: 10.2478/v10168-010-0003-7
Abstract: In this paper, numerical results of modeling of acoustic waves propagation are presented. For calculation of the acoustic fluctuations, a solution of the full non-linear Euler equation is used. The Euler equations are solved with the use of a numerical scheme of third-order accuracy in space and time. The paper shows a validation process of the described method. This method is suitable also for an aerodynamic noise assessment on the basis of unsteady mean flow field data obtained from a CFD calculations. In such case this method is called a hybrid CFD/CAA method. The proposed method is numerically decoupled with CFD solution, therefore the information about the mean unsteady flow field can be obtained using an arbitrary CFD method (solver). The accuracy of the acoustic field assessment depends on the quality of the CFD solutions. This decomposition reduces considerably the computational cost in comparison with direct noise calculations. The presented Euler acoustic postprocessor (EAP) has been used for modeling of the acoustic waves propagation in a cavity and in the flow field around a cylinder and an aerodynamic profile.
On the effective lagrangian in spinor electrodynamics with added violation of Lorentz and CPT symmetries
Yu. A. Sitenko,K. Yu. Rulik
Physics , 2002, DOI: 10.1140/epjc/s2003-01167-7
Abstract: We consider quantum electrodynamics with additional coupling of spinor fields to the space-time independent axial vector violating both Lorentz and CPT symmetries. The Fock-Schwinger proper time method is used to calculate the one-loop effective action up to the second order in the axial vector and to all orders in the space-time independent electromagnetic field strength. We find that the Chern-Simons term is not radiatively induced and that the effective action is CPT invariant in the given approximation.
Time-Dependent Ferrofluid Dynamics in Symmetry Breaking Transverse  [PDF]
Sebastian Altmeyer
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.32015
Abstract: We investigate the Taylor-Couette flow of a rotating ferrofluid under the influence of symmetry breaking transverse magnetic field in counter-rotating small-aspect-ratio setup. We find only changing the magnetic field strength can drive the dynamics from time-periodic limit-cycle solution to time-independent steady fixed-point solution and vice versa. Thereby both solutions exist in symmetry related offering mode-two symmetry with left-or right-winding characteristics due to finite transverse magnetic field. Furthermore the time-periodic limit-cycle solutions offer alternately stroboscoping both helical left-and right-winding contributions of mode-two symmetry. The Navier-Stokes equations are solved with a second order time splitting method combined with spatial discretization of hybrid finite difference and Galerkin method.
Structure of Relatively Accelerating Universe  [PDF]
Aloysius Sebastian
International Journal of Astronomy and Astrophysics (IJAA) , 2014, DOI: 10.4236/ijaa.2014.41015
Abstract:

This article is about the structure of expanding universe. Here I am trying to create a structural model of universe according to my thoughts. Studies showthat universe is accelerating its rate of expansion. Here I am trying to get some conclusions according to my thoughts. In my opinion, our universe is under a gravitational frame with all the matters in it. In this gravitational frame of universe we can consider our universe as a closed system and the empty space outside the frame as an open system. There are two possibilities we can find. One is relative motion of the objects inside the frame. By this way we can feel the universe is accelerating its expansion, but it is not. Another one is the vacuum energy absorption and negative pressure inside the frame. According to this thought, we can say that universe is accelerating and it can continue its motion at present conditions on it, even the force created by the big bang is decreasing. The other point is that, once the absorbed vacuum can create a negative pressure inside the frame, there is no need for the concept of dark energy in our universe [1]. According to this model, negative pressure inside the frame will be created by the absorbed vacuum from the space. So the

The Post-Transcriptional mRNA Editing Analysis of cox3 Mitochondrial Gene in Fern Asplenium nidus Reveals Important Features  [PDF]
Sebastian Panarese, Guglielmo Rainaldi
American Journal of Plant Sciences (AJPS) , 2011, DOI: 10.4236/ajps.2011.24063
Abstract: In the mitochondria and chloroplasts of flowering plants (angiosperms), transcripts of protein-coding genes are altered after synthesis so that their final primary nucleotide sequence differs from that of the corresponding DNA sequence. This posttranscriptional mRNA editing consists almost exclusively of C-to-U substitutions (direct) and less frequently of U-to-C substitution (reverse). Editing occurs predominantly within coding regions, mostly at isolated C residues, and usually at first or second positions of codons, thereby almost always changing the amino acid from that specified by the unedited codon. Editing may also create initiation and termination codons. The effect of C-to-U RNA editing in plants is to make proteins encoded by plant organelles more similar in sequence to their non plant homologs, then specific C-to- U editing events are essential for the production of functional plant mitochondrial proteins. Our attention has been devoted to the study of the mRNA editing in cox3 mitochondrial gene of fern Asplenium nidus. This study reveals the extreme importance of both C-to-U and U-to-C substitutions for protein expression.
Corporate Deductibility Provisions and Financial Constraints of Innovative Entrepreneurs  [PDF]
Wolfgang Eggert, Sebastian Heitzmann
Theoretical Economics Letters (TEL) , 2017, DOI: 10.4236/tel.2017.76108
Abstract: Corporate income tax systems around the world typically favor debt over equity in the tax base definition. The resulting distortions on financing and investment decisions of corporations are well documented in the existing literature. In this paper, we focus on the ACE proposal by the Mirrlees Review [1]. It is shown that an ACE, which mitigates the unequal treatment of returns to owned and borrowed capital, fosters innovation by financing startups.
Austria’s Path to a Climate-Friendly Society and Economy—Contributions of an Environmental Tax Reform  [PDF]
Sebastian Goers, Friedrich Schneider
Modern Economy (ME) , 2019, DOI: 10.4236/me.2019.105092
Abstract: In the present study, we explore an environmental tax reform for Austria as an instrument to achieve the main objectives of the current Austrian Climate and Energy Strategy #mission2030. Our concept aims at a dual objective of reducing CO2-eq emissions, while simultaneously further triggering innovation processes of the Austrian industry, resulting in a transfer of benefits to society. The focused measures at the national level to achieve climate protection comprise an increase of the mineral oil tax and the introduction of CO2-eq taxation for non-EU-ETS sectors. These taxes create revenues which are recycled through 1) reductions of non-wage labor costs for companies, 2) compensation transfers for private households of low- and middle-income groups, 3) investment in research and innovation for industry and 4) investments in key technologies to advance #mission2030, such as alternative propulsion systems (electric, H2), and the use of biomethane for space heating and thermal renovation. Results of simulations for the period 2020 to 2025 via a macro-sectoral model display the potential for multiple dividends if the revenues are reused this way. Furthermore, besides offering significant reductions of CO2e emissions, the proposed reform triggers positive impacts on GDP, employment, and private consumption, thereby ensuring social compatibility.
Fast and Tiny Structural Self-Indexes for XML
Sebastian Maneth,Tom Sebastian
Computer Science , 2010,
Abstract: XML document markup is highly repetitive and therefore well compressible using dictionary-based methods such as DAGs or grammars. In the context of selectivity estimation, grammar-compressed trees were used before as synopsis for structural XPath queries. Here a fully-fledged index over such grammars is presented. The index allows to execute arbitrary tree algorithms with a slow-down that is comparable to the space improvement. More interestingly, certain algorithms execute much faster over the index (because no decompression occurs). E.g., for structural XPath count queries, evaluating over the index is faster than previous XPath implementations, often by two orders of magnitude. The index also allows to serialize XML results (including texts) faster than previous systems, by a factor of ca. 2-3. This is due to efficient copy handling of grammar repetitions, and because materialization is totally avoided. In order to compare with twig join implementations, we implemented a materializer which writes out pre-order numbers of result nodes, and show its competitiveness.
XPath Node Selection over Grammar-Compressed Trees
Sebastian Maneth,Tom Sebastian
Computer Science , 2013, DOI: 10.4204/EPTCS.134.5
Abstract: XML document markup is highly repetitive and therefore well compressible using grammar-based compression. Downward, navigational XPath can be executed over grammar-compressed trees in PTIME: the query is translated into an automaton which is executed in one pass over the grammar. This result is well-known and has been mentioned before. Here we present precise bounds on the time complexity of this problem, in terms of big-O notation. For a given grammar and XPath query, we consider three different tasks: (1) to count the number of nodes selected by the query, (2) to materialize the pre-order numbers of the selected nodes, and (3) to serialize the subtrees at the selected nodes.
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