Inhaltsverzeichnis
Auswahl der wissenschaftlichen Literatur zum Thema „CALCULATIONS AND SIMULATIONS IN ANOTHER FORM“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit den Listen der aktuellen Artikel, Bücher, Dissertationen, Berichten und anderer wissenschaftlichen Quellen zum Thema "CALCULATIONS AND SIMULATIONS IN ANOTHER FORM" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Zeitschriftenartikel zum Thema "CALCULATIONS AND SIMULATIONS IN ANOTHER FORM"
1
Silvestrov, P. V., und S. T. Surzhikov. „Numerical Simulation of the HIFiRE-1 Ground Test“. Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, Nr. 3 (132) (Juni 2020): 29–46. http://dx.doi.org/10.18698/0236-3941-2020-3-29-46.
Der volle Inhalt der QuelleAnnotation:
The paper considers the problem of simulating the HIFiRE-1 ground test numerically. The aircraft geometry is represented by either a pointed or a blunted cone combined with a flared cylinder. Our digital simulation investigated the aerodynamics of two aircraft configurations: one featuring a pointed nose, another featuring a blunted nose with a radius of 2.5 mm. We used the UST3D software developed in the Ishlinsky Institute for Problems in Mechanics RAS, to perform our aerodynamic calculations. The software is specifically designed for numerical simulations of aerodynamics and thermodynamics in high-velocity aircraft. It implements a model of viscous compressible thermally conductive gas described by a non-steady-state spatial system of Navier --- Stokes equations solved over unstructured three-dimensional tetrahedral meshes. We compared the numerical simulation results in the form of pressure distribution in the tail segment of the aircraft to the empirical data obtained via ground tests in a wind tunnel. We analysed result convergence as a function of the mesh density used. We used methods of computational aerodynamics to investigate the turbulent flow field over the computation region from the leading shock wave to the far wake for various Mach numbers and attack angles
2
Saeedian, Meysam, Edris Pouresmaeil, Emad Samadaei, Eduardo Manuel Godinho Rodrigues, Radu Godina und Mousa Marzband. „An Innovative Dual-Boost Nine-Level Inverter with Low-Voltage Rating Switches“. Energies 12, Nr. 2 (09.01.2019): 207. http://dx.doi.org/10.3390/en12020207.
Der volle Inhalt der QuelleAnnotation:
This article presents an innovative switched-capacitor based nine-level inverter employing single DC input for renewable and sustainable energy applications. The proposed configuration generates a step-up bipolar output voltage without end-side H-bridge, and the employed capacitors are charged in a self-balancing form. Applying low-voltage rated switches is another merit of the proposed inverter, which leads to extensive reduction in total standing voltage. Thereby, switching losses as well as inverter cost are reduced proportionally. Furthermore, the comparative analysis against other state-of-the-art inverters depicts that the number of required power electronic devices and implementation cost is reduced in the proposed structure. The working principle of the proposed circuit along with its efficiency calculations and thermal modeling are elaborated in detail. In the end, simulations and experimental tests are conducted to validate the flawless performance of the proposed nine-level topology in power systems.
3
Kurkus-Gruszecka, Michalina, und Piotr Krawczyk. „Comparison of Two Single Stage Low-Pressure Rotary Lobe Expander Geometries in Terms of Operation“. Energies 12, Nr. 23 (27.11.2019): 4512. http://dx.doi.org/10.3390/en12234512.
Der volle Inhalt der QuelleAnnotation:
In the article the computational fluid dynamics (CFD) simulation and calculated operational parameters of the single stage low-pressure rotary lobe expander compared with the values obtained from a different geometry simulation are presented. Low-pressure rotary lobe expanders are rotary engines that use a compressed gas to produce mechanical energy, which in turn can be converted into another form, i.e., electric energy. Currently, expanders are used in narrow areas, but have a large potential in the energy production from gases of low thermodynamic parameters. The first geometry model was designed on the basis of an industrial device and validated with the empirical data. Simulation of the second geometry was made based on a validated model in order to estimate the operational parameters of the device. The CFD model included the transient simulation of compressible fluid in the geometry changing over time and the rotors motion around two rotation axes. The numerical model was implemented in ANSYS CFX software. After obtaining simulation results in the form of parameters monitors for each time step, a number of calculations were performed using a written code analysing the CFD program output files. The article presents the calculation results and the geometries comparison in terms of work efficiency. The research indicated that the construction of the device on a small scale could cause a significant decrease in the aforementioned parameter, caused by medium leaks in the expander clearances.
4
MELIGA, PHILIPPE, JEAN-MARC CHOMAZ und DENIS SIPP. „Global mode interaction and pattern selection in the wake of a disk: a weakly nonlinear expansion“. Journal of Fluid Mechanics 633 (25.08.2009): 159–89. http://dx.doi.org/10.1017/s0022112009007290.
Der volle Inhalt der QuelleAnnotation:
Direct numerical simulations (DNS) of the wake of a circular disk placed normal to a uniform flow show that, as the Reynolds number is increased, the flow undergoes a sequence of successive bifurcations, each state being characterized by specific time and space symmetry breaking or recovering (Fabre, Auguste & Magnaudet, Phys. Fluids, vol. 20 (5), 2008, p. 1). To explain this bifurcation scenario, we investigate the stability of the axisymmetric steady wake in the framework of the global stability theory. Both the direct and adjoint eigenvalue problems are solved. The threshold Reynolds numbers Re and characteristics of the destabilizing modes agree with the study of Natarajan & Acrivos (J. Fluid Mech., vol. 254, 1993, p. 323): the first destabilization occurs for a stationary mode of azimuthal wavenumber m = 1 at RecA = 116.9, and the second destabilization of the axisymmetric flow occurs for two oscillating modes of azimuthal wavenumbers m ± 1 at RecB = 125.3. Since these critical Reynolds numbers are close to one another, we use a multiple time scale expansion to compute analytically the leading-order equations that describe the nonlinear interaction of these three leading eigenmodes. This set of equations is given by imposing, at third order in the expansion, a Fredholm alternative to avoid any secular term. It turns out to be identical to the normal form predicted by symmetry arguments. Though, all coefficients of the normal form are here analytically computed as the scalar product of an adjoint global mode with a resonant third-order forcing term, arising from the second-order base flow modification and harmonics generation. We show that all nonlinear interactions between modes take place in the recirculation bubble, as the contribution to the scalar product of regions located outside the recirculation bubble is zero. The normal form accurately predicts the sequence of bifurcations, the associated thresholds and symmetry properties observed in the DNS calculations.
5
HOROWITZ, C. J. „MULTI-MESSENGER OBSERVATIONS OF NEUTRON-RICH MATTER“. International Journal of Modern Physics E 20, Nr. 10 (Oktober 2011): 2077–100. http://dx.doi.org/10.1142/s0218301311020332.
Der volle Inhalt der QuelleAnnotation:
At very high densities, electrons react with protons to form neutron-rich matter. This material is central to many fundamental questions in nuclear physics and astrophysics. Moreover, neutron-rich matter is being studied with an extraordinary variety of new tools such as Facility for Rare Isotope Beams (FRIB) and the Laser Interferometer Gravitational Wave Observatory (LIGO). We describe the Lead Radius Experiment (PREX) that uses parity violating electron scattering to measure the neutron radius in 208Pb. This has important implications for neutron stars and their crusts. We discuss X-ray observations of neutron star radii. These also have important implications for neutron-rich matter. Gravitational waves (GW) open a new window on neutron-rich matter. They come from sources such as neutron star mergers, rotating neutron star mountains, and collective r-mode oscillations. Using large scale molecular dynamics simulations, we find neutron star crust to be very strong. It can support mountains on rotating neutron stars large enough to generate detectable gravitational waves. Finally, neutrinos from core collapse supernovae (SN) provide another, qualitatively different probe of neutron-rich matter. Neutrinos escape from the surface of last scattering known as the neutrino-sphere. This is a low density warm gas of neutron-rich matter. Neutrino-sphere conditions can be simulated in the laboratory with heavy ion collisions. Observations of neutrinos can probe nucleosyntheses in SN. Simulations of SN depend on the equation of state (EOS) of neutron-rich matter. We discuss a new EOS based on virial and relativistic mean field calculations. We believe that combing astronomical observations using photons, GW, and neutrinos, with laboratory experiments on nuclei, heavy ion collisions, and radioactive beams will fundamentally advance our knowledge of compact objects in the heavens, the dense phases of QCD, the origin of the elements, and of neutron-rich matter.
6
Belczynski, K., A. Askar, M. Arca-Sedda, M. Chruslinska, M. Donnari, M. Giersz, M. Benacquista et al. „The origin of the first neutron star – neutron star merger“. Astronomy & Astrophysics 615 (Juli 2018): A91. http://dx.doi.org/10.1051/0004-6361/201732428.
Der volle Inhalt der QuelleAnnotation:
The first neutron star-neutron star (NS-NS) merger was discovered on August 17, 2017 through gravitational waves (GW170817) and followed with electromagnetic observations. This merger was detected in an old elliptical galaxy with no recent star formation. We perform a suite of numerical calculations to understand the formation mechanism of this merger. We probe three leading formation mechanisms of double compact objects: classical isolated binary star evolution, dynamical evolution in globular clusters, and nuclear cluster formation to test whether they are likely to produce NS-NS mergers in old host galaxies. Our simulations with optimistic assumptions show current NS-NS merger rates at the level of 10−2 yr−1 from binary stars, 5 × 10−5 yr−1 from globular clusters, and 10−5 yr−1 from nuclear clusters for all local elliptical galaxies (within 100 Mpc3). These models are thus in tension with the detection of GW170817 with an observed rate of 1.5−1.2+3.2 yr−1 (per 100 Mpc3; LIGO/Virgo 90% credible limits). Our results imply that either the detection of GW170817 by LIGO/Virgo at their current sensitivity in an elliptical galaxy is a statistical coincidence; that physics in at least one of our three models is incomplete in the context of the evolution of stars that can form NS-NS mergers; or that another very efficient (unknown) formation channel with a long delay time between star formation and merger is at play.
7
Lanets, Oleksii, Oleksandr Kachur und Vitaliy Korendiy. „Classical approach to determining the natural frequency of continual subsystem of three-mass inter-resonant vibratory machine“. Ukrainian journal of mechanical engineering and materials science 5, Nr. 3-4 (2019): 77–87. http://dx.doi.org/10.23939/ujmems2019.03-04.077.
Der volle Inhalt der QuelleAnnotation:
Problem statement. The three-mass vibratory system can be defined by five basic parameters: inertial parameters of the masses and stiffness parameters of two spring sets. Unlike the classical discrete system, the discrete-and-continual one consists of two rigid bodies connected by one spring set that form the discrete subsystem, and of the reactive mass considered as deformable (elastic) body characterized by certain stiffness and inertial parameters, which are related with one another. Purpose. The main objective of the paper consists in determining the first natural frequency of the continual subsystem of the three-mass discrete-and-continual vibratory machine. Methodology. While carrying out the investigations, it is used the classical theory of oscillations of straight elastic rods. Findings (results). The engineering technique of determining the first natural frequency of the continual subsystem of the three-mass vibratory machine is developed and approved by means of analytical calculations and numerical simulation. Originality (novelty). The optimal diagram of supporting the continual subsystem (elastic rod) is substantiated. The possibilities of exciting the vibrations of the three-mass discrete-and-continual mechanical system using the eccentric drive are considered. Practical value. The obtained research results and the developed calculation techniques can be used be engineers and designers dealing with various technological and manufacturing equipment that use vibratory drive. Scopes of further investigations. While carrying out further investigations, it is necessary to develop the model of combined discrete-and-continual system of three-mass vibratory machine, and to carry out the numerical simulation of the system’s motion under different operational conditions.
8
Fan, Dan, und Kueiming Lo. „Recursive Identification for Dynamic Linear Systems from Noisy Input-Output Measurements“. Journal of Applied Mathematics 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/318786.
Der volle Inhalt der QuelleAnnotation:
Errors-in-variables (EIV) model is a kind of model with not only noisy output but also noisy input measurements, which can be used for system modeling in many engineering applications. However, the identification for EIV model is much complicated due to the input noises. This paper focuses on the adaptive identification problem of real-time EIV models. Some derivation errors in an accuracy research of the popular Frisch scheme used for EIV identification have been pointed out in a recent study. To solve the same modeling problem, a new algorithm is proposed in this paper. A Moving Average (MA) process is used as a substitute for the joint impact of the mutually independent input and output noises, and then system parameters and the noise properties are estimated in the view of the time domain and frequency domain separately. A recursive form of the first step calculation is constructed to improve the calculation efficiency and online computation ability. Another advantage of the proposed algorithm is its applicableness to different input processes situations. Numerical simulations are given to demonstrate the efficiency and robustness of the new algorithm.
9
Pop, L., D. Hanslian und J. Hošek. „Mapping of extreme wind speed for landscape modelling of the Bohemian Forest, Czech Republic“. Natural Hazards and Earth System Sciences Discussions 2, Nr. 1 (17.01.2014): 361–84. http://dx.doi.org/10.5194/nhessd-2-361-2014.
Der volle Inhalt der QuelleAnnotation:
Abstract. Extreme wind events are among the most damaging weather-related hazards in the Czech Republic, forestry is heavily affected. In order to successfully run a landscape model dealing with such effects, spatial distribution of extreme wind speed statistics is needed. The presented method suggests using sector-wise wind field calculations together with extreme value statistics fitted at a reference station. A special algorithm is proposed to provide the data in the form expected by the landscape model, i.e. raster data of annual wind speed maxima. The method is demonstrated on the area of Bohemian Forest that represents one of largest and most compact forested mountains in Central Europe. The reference meteorological station Churáňov is located within the selected domain. Numerical calculations were based on linear model of WAsP Engineering methodology. Observations were cleaned of inhomogeneity and classified into convective and non-convective cases using index CAPE. Due to disjunct sampling of synoptic data, appropriate corrections were applied to the observed extremes. Finally they were fitted with Gumbel distribution. The output of numerical simulation is presented for the windiest direction sector. Another map shows probability that annual extreme exceeds required threshold. The method offers a tool for generation of spatially variable annual maxima of wind speed. It assumes a small limited model domain containing a reliable wind measurement. We believe that this is typical setup for applications similar to one presented in the paper.
10
Sweeney, J. „Finite-Width correction factors for sen testing of orthotropic materials in opening mode“. Journal of Strain Analysis for Engineering Design 21, Nr. 2 (01.04.1986): 99–107. http://dx.doi.org/10.1243/03093247v212099.
Der volle Inhalt der QuelleAnnotation:
Calculations of finite-width correction factors, Y, for mode I SEN tension testing of orthotropic materials have been made using a J integral implemented on results from finite element analyses. Y depends on the ratio of principal normal compliances S11/ S22 and another dimensionless quantity involving the material compliances. Aspect ratio is fixed at 1 and normalized crack depth varies between 0.3 and 0.6. S11/ S22 is fixed at four values; 20, 10, 1/10, and 1/20. Ranges of the other dimensionless material parameter relevant to existing materials are chosen. The use of linear interpolation for Y at intermediate values of S11/ S22, and the relevance of the results to specimens with aspect ratios in excess of 1, are discussed. Y is presented at each value of S11/ S22 in the form of a Chebyshev series in two variables. The results show that, if Y factors already established for isotropic materials are used to calculate stress intensity values for orthotropic specimens, errors in the stress intensity factor can be as high as 50 per cent.
Dissertationen zum Thema "CALCULATIONS AND SIMULATIONS IN ANOTHER FORM"
1
Maštera, Lukáš. „Koncepce vysokorychlostní vrtné hlavy pro odběr vzorků hornin“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443237.
Der volle Inhalt der QuelleAnnotation:
THE THESIS FOCUSES ON A CONSTRUCTION DESIGN OF A NEW DRILLING HEAD DESIGNED TO REPLACE THE ORIGINAL ONE IN A MULTIDRILL HYNDAGA DRILLING RING. THE SUBSTITUTION IS SUPPOSED TO PROVIDE A SOLUTION TO THE SHORTCOMINGS OF THE CURRENTLY USED DRILLING HEAD. THE THESIS ANALYSES PARAMETERS OBTAINED FROM THE MANUFACTURER, NEW PRODUCTION REQUIREMENTS AND PROPOSES TWO TYPES OF MOTORS INNOVATIVE METHODS HAD BEEN IMPLEMENTED IN CALCULATIONS OF CONCEPTUAL PARAMETERS OF THE NECESSARY COMPONENTS. THE OUTCOME IS A NEW F-TYPE DRILLING HEAD.
Buchteile zum Thema "CALCULATIONS AND SIMULATIONS IN ANOTHER FORM"
1
Erman, Burak, und James E. Mark. „Calculations and Simulations“. In Structures and Properties of Rubberlike Networks. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195082371.003.0010.
Der volle Inhalt der QuelleAnnotation:
The classical theories of rubber elasticity are based on the Gaussian chain model. The only molecular parameter that enters these theories is the mean-square end-to-end separation of the chains constituting the network. However, there are various areas of interest that require characterization of molecular quantities beyond the Gaussian description. Examples are segmental orientation, birefringence, rotational isomerization, and finite extensibility, and we will address these properties in the following chapters. One often needs a more realistic distribution function for the end-to-end vector, as well as for averages of the products of several vectorial quantities, as will be evident in these chapters. The foundations for such characterizations, and several examples of their applications, are given in this chapter. Several aspects of rubber elasticity (such as the dependence of the elastic free energy on network topology, number of effective junctions, and contributions from entanglements) are successfully explained by theories based on the freely jointed chain and the Gaussian approximation. Details of the real chemical structure are not required at the length scales describing these phenomena. On the other hand, studies of birefringence, thermoelasticity, rotational isomerization upon stretching, strain dichroism, local segmental orientation and mobility, and characterization of networks with short chains require the use of more realistic network chain models. In this section, properties of rotational isomeric state models for the chains are discussed. The notation is based largely on the Flory book, Statistical Mechanics of Chain Molecules. More recent information is readily found in the literature. Due to the simplicity of its structure, a polyethylene-like chain serves as a convenient model for discussing the statistical properties of real chains. This simplicity can be seen in figure 8.1, which shows the planar form of a small portion of a polyethylene chain. Bond lengths and bond angles may be regarded as fixed in the study of rubber elasticity because their rapid fluctuations are usually in the range of only ±0.05 A and ±5°, respectively. The chain changes its configuration only through torsional rotations about the backbone bonds, shown, for example, by the angle for the ith bond in figure 8.1.
2
Nicolaos, Bilalis, und Petousis Markos. „A Virtual Environment for Machining Operations Simulation and Machining Evaluation“. In Virtual Technologies for Business and Industrial Applications, 88–104. IGI Global, 2011. http://dx.doi.org/10.4018/978-1-61520-631-5.ch005.
Der volle Inhalt der QuelleAnnotation:
A virtual reality machine shop environment has been developed capable of simulating the operation of a three axis milling machine and it has been integrated with a graphical model for the calculation of quantitative data affecting the machined surface roughness. The model determines the machined surface topomorphy as a cloud of points, retrieved from the visualization system Z buffer. The current study describes the developed model for milling processes simulation in a virtual environment and the determination of the surface roughness of the processed surfaces. Also, the methodology for the verification of the quantitative data acquired by the system is presented. Results were verified with data determined in cutting experiments and by another numerical model that was integrated to the system.
3
Raff, Lionel, Ranga Komanduri, Martin Hagan und Satish Bukkapatnam. „Neural Network Methods for Data Analysis and Statistical Error Reduction“. In Neural Networks in Chemical Reaction Dynamics. Oxford University Press, 2012. http://dx.doi.org/10.1093/oso/9780199765652.003.0013.
Der volle Inhalt der QuelleAnnotation:
The use of neural networks (NNs) to predict an outcome or the output results as a function of a set of input parameters has been gaining wider acceptance with the advance in computer technology as well as with an increased awareness of the potential of NNs. A neural network is first trained to learn the underlying functional relationship between the output and the input parameters by providing it with a large number of data points, where each data point corresponds to a set of output and input parameters. Sumpter and Noid demonstrated the use of NNs to map the vibrational motion derived from the vibrational spectra onto a PES with relatively high accuracy. In another application, Sumpter et al. trained an NN to learn the relation between the phase-space points along a trajectory and the mode energies for stretching, torsion, and bending vibrations of H2O2. Likewise, Nami et al. demonstrated the use of NNs to determine the TiO2 deposition rates in a chemical vapor deposition (CVD) process from the knowledge of a range of deposition conditions. In view of the success achieved in obtaining interpolated values of the PESs for multi-atomic systems using an NN trained by the ab initio energy values for a large number of configurations, it is reasonable to ask whether we can successfully compute the results of an MD trajectory for a chemical reaction using an NN trained by the data obtained by previous MD simulations. If this can be done successfully, it becomes possible to execute a small number of trajectories, M, and then utilize the results of these trajectories as a database to train an NN to predict the final results of a very large number of trajectories N, where N >> M, that can be used to increase the statistical accuracy of the MD calculations and to further explore the dependence of the trajectory results upon a wide variety of variables without actually having to perform any further numerical integrations. In effect, the NN replaces the computationally laborious numerical integrations.
4
Swendsen, Robert H. „Ensembles in Classical Statistical Mechanics“. In An Introduction to Statistical Mechanics and Thermodynamics, 231–57. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198853237.003.0019.
Der volle Inhalt der QuelleAnnotation:
This chapter explores more powerful methods of calculation than were seen previously. Among them are Molecular Dynamics (MD) and Monte Carlo (MC) computer simulations. Another is the canonical partition function, which is related to the Helmholtz free energy. The derivation of thermodynamic identities within statistical mechanics is illustrated by the relationship between the specific heat and the fluctuations of the energy. It is shown how the canonical ensemble allows us to integrate out the momentum variables for many classical models. The factorization of the partition function is presented as the best trick in statistical mechanics, because of its central role in solving problems. Finally, the problem of many simple harmonic oscillators is solved, both for its importance and as an illustration of the best trick.
5
Walker, James C. G. „Climate: A Chain of Identical Reservoirs“. In Numerical Adventures with Geochemical Cycles. Oxford University Press, 1991. http://dx.doi.org/10.1093/oso/9780195045208.003.0009.
Der volle Inhalt der QuelleAnnotation:
One class of important problems involves diffusion in a single spatial dimension, for example, height profiles of reactive constituents in a turbulently mixing atmosphere, profiles of concentration as a function of depth in the ocean or other body of water, diffusion and diagenesis within sediments, and calculation of temperatures as a function of depth or position in a variety of media. The one-dimensional diffusion problem typically yields a chain of interacting reservoirs that exchange the species of interest only with the immediately adjacent reservoirs. In the mathematical formulation of the problem, each differential equation is coupled only to adjacent differential equations and not to more distant ones. Substantial economies of computation can therefore be achieved, making it possible to deal with a larger number of reservoirs and corresponding differential equations. In this chapter I shall explain how to solve a one-dimensional diffusion problem efficiently, performing only the necessary calculations. The example I shall use is the calculation of the zonally averaged temperature of the surface of the Earth (that is, the temperature averaged over all longitudes as a function of latitude). I first present an energy balance climate model that calculates zonally averaged temperatures as a function of latitude in terms of the absorption of solar energy, which is a function of latitude, the emission of long-wave planetary radiation to space, which is a function of temperature, and the transport of heat from one latitude to another. This heat transport is represented as a diffusive process, dependent on the temperature gradient or the difference between temperatures in adjacent latitude bands. I use the energy balance climate model first to calculate annual average temperature as a function of latitude, comparing the calculated results with observed values and tuning the simulation by adjusting the diffusion parameter that describes the transport of energy between latitudes. I then show that most of the elements of the sleq array for this problem are zero. Nonzero elements are present only on the diagonal and immediately adjacent to the diagonal. The array has this property because each differential equation for temperature in a latitude band is coupled only to temperatures in the adjacent latitude bands.
6
Walker, James C. G. „How to Calculate Isotope Ratios“. In Numerical Adventures with Geochemical Cycles. Oxford University Press, 1991. http://dx.doi.org/10.1093/oso/9780195045208.003.0008.
Der volle Inhalt der QuelleAnnotation:
The calculation of isotope ratios requires special consideration because isotope ratios, unlike matter or energy, are not conserved. In this chapter I shall show how extra terms arise in the equations for the rates of change of isotope ratios. The equations developed here are quite general and can be applied to most of the isotope systems used in geochemistry. As an example of the application of these new equations, I shall demonstrate a simulation of the carbon isotopic composition of ocean and atmosphere and then use this simulation to examine the influence on carbon isotopes of the combustion of fossil fuels. As an alternative application I shall simulate the carbon isotopic composition of the water in an evaporating lagoon and show how the composition and other properties of this water might be affected by seasonal changes in evaporation rate, water temperature, and biological productivity. Equations for the rates of change of individual isotopes in a reservoir are not essentially different from the equations for the rates of change of chemical species. Isotopic abundances, however, are generally expressed as ratios of one isotope to another and, moreover, not just as the ratio but also as the departure of the ratio from a standard. This circumstance introduces some algebra into the derivation of an isotopic conservation equation. It is convenient to pursue this algebra just once, as I shall in this section, after which all isotope simulations can be formulated in the same way. I shall use the carbon isotopes to illustrate this derivation, but the same approach can be used for the isotopes of other elements, such as sulfur, oxygen, nitrogen, hydrogen, or strontium. The most abundant isotope of carbon has a mass of 12 atomic mass units, 12C. A less abundant stable isotope is 13C. And much less abundant is the radioactive isotope 14C, also called radiocarbon. It is convenient to express the abundances of these rare isotopes in terms of ratios of the number of atoms of the rare isotope in a sample to the number of atoms of the abundant isotope. We call this ratio r, generally a very small number.
7
Durga, Shree, und Kurt Squire. „Productive Gaming and the Case for Historiographic Game-Play“. In Handbook of Research on Effective Electronic Gaming in Education, 200–218. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-59904-808-6.ch012.
Der volle Inhalt der QuelleAnnotation:
This chapter examines the potential of video games as a learning tool given their productive capacity for content creation and dissemination. Based on the findings from a longitudinal, twoyear design-based research study investigating the potential of learning communities constructed around using Civilization III (a turn-based historical simulation-strategy game), the chapter argues that historical model construction is a compelling way to mediate one’s understandings about history. Participants in this game- based learning program developed new identities as producers as well as consumers of historical simulations. Two distinct trajectories of expertise were found to be emerging: one that developed around expert, systemic gaming (orienting toward the experience as a game system), and another that we call historical gaming, orienting to the game experience as a form of “replaying history.” Both forms have value, emphasizing different aspects of the game system. We believe that a community tying these two forms of gaming together (and other ones, as they emerge) is key for building robust learning environments.
8
Tarnowski, Wojciech. „Fuzzy and Soft Poly-Optimization in the Digital Environment“. In Fuzzy Optimization and Multi-Criteria Decision Making in Digital Marketing, 180–200. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-4666-8808-7.ch009.
Der volle Inhalt der QuelleAnnotation:
TThe standard optimality problem is when the triad is given: <x, F(x), O(x)>, where x is the decision variables vector, F(x) is an overall optimality criterion and O(x) is a set of constraints, defined in a fully mathematical form. But in the real practice in business, logistics, medicine, and even in engineering – where a decision–maker has for his/her disposal comparatively good unique mathematical models – it is very rarely. Another trouble may be, the computations are time consuming and/or algorithms do not converged satisfactory. In this chapter examples of two non-standard techniques of poly-optimization (Multi Attribute Decision Making, Multi Criteria Decision Making) are presented. The first is a dialog procedure of finding satisfactory solution on hierarchical play of constraints, with extensive computer simulations, what is called here as a soft optimization. The other is a standard poly-optimization on fuzzy mathematical definition of criteria and of a model. A few examples are given.
9
Harrison, Roger G., Paul W. Todd, Scott R. Rudge und Demetri P. Petrides. „Drying“. In Bioseparations Science and Engineering. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780195391817.003.0014.
Der volle Inhalt der QuelleAnnotation:
The last step in the separation process for a biological product is usually drying, which is the process of thermally removing volatile substances (often water) to yield a solid. In the step preceding drying, the desired product is generally in an aqueous solution and at the desired final level of purity. The most common reason for drying a biological product is that it is susceptible to chemical (e.g., deamidation or oxidation) and/or physical (e.g., aggregation and precipitation) degradation during storage in a liquid formulation. Another common reason for drying is for convenience in the final use of the product. For example, it is often desirable that pharmaceutical drugs be in tablet form. Additionally, drying may be necessary to remove undesirable volatile substances. Also, although many bioproducts are stable when frozen, it is more economical and convenient to store them in dry form rather than frozen. Drying is now an established unit operation in the process industries. However, because most biological products are thermally labile, only those drying processes that minimize or eliminate thermal product degradation are actually used to dry biological products. This chapter focuses on the types of dryer that have generally found the greatest use in the drying of biological products: vacuum-shelf dryers, batch vacuum rotary dryers, freeze dryers, and spray dryers [1]. The principles discussed, however, will apply to other types of dryers as well. We begin with the fundamental principles of drying, followed by a description of the types of dryer most used for biological products. Then we present scale-up and design methods for these dryers. After completing this chapter, the reader should be able to do the following: • Do drying calculations involving relative humidity using the psychrometric moisture chart and the equilibrium moisture curve for the material being dried. • Calculate the relative amounts of bound and unbound water in wet solids before drying. • Model heat transfer in conductive drying and calculate conductive drying times. • Interpret drying rate curves. • Calculate convective drying times of nonporous solids based on mass transfer.
10
Proserpio, Luigi. „Managerial Computer Business Games“. In Encyclopedia of Multimedia Technology and Networking, Second Edition, 873–79. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-014-1.ch119.
Der volle Inhalt der QuelleAnnotation:
Interview with Anthony Davidson, SuperAguri F1 GP Driver (autosport.com, March 2, 2007): Q: Can you actually learn anything from the [F1 videogame] though? AD: Absolutely. When I did the 2004 season, I really relied on having video data from the team and using the PlayStation games as well to learn the circuits. We always deal in corner numbers, we don’t use the proper corner names, so we have a little map in the car with the numbers. For you to visualize it beforehand is a help, because when they talk about a bump in turn three then you know what they are talking about before you have even walked the circuit or seen any onboard footage. You know roughly what the track looks like and when you get out there you smile because it is exactly what you were doing in your living room. And now the graphics have stepped up another level it is so much more realistic. F1 drivers can benefit from computer simulations, with a supplement of training before racing on a newly built circuit, with no consolidated knowledge. Managers (and students, too) can benefit from PC-based simulations that recreate complex business worlds as well. Books contain theories, along with a good number of examples. Computer-based business games can add dynamism and a temporal dimension to the standard managerial theories contained in books. Many researchers think that the potential of the computer as a learning tool is very high if we involve the user in a simulation process, instead of giving him a description of reality. This theory is confirmed by many field examples, as shown before by the Formula 1 pilot, who adopts a particular software in order to learn how to drive on a circuit that he has not tested directly. U.S. Marines play Quake and Unreal to simulate the mission in which they will be involved. Business games, finally, start to be adopted in managerial education as learning support tools. For example, EIS simulation has been developed at Insead Business School in order to simulate organizational change, while FirmReality has been developed at Bocconi University to study the integrated use of organizational capabilities to gain competitive advantage. Scientific and managerial literatures recognize the potential of these instruments for learning purposes (compatible with andragogical and collaborative learning theories), but cannot address their design and the integration within distance-learning practices. The current debate on computer simulations involves the research and the standardization of rules for the project phases, in order to take advantage of the potential attributed to this tool, and enhance the compatibility between managers/students and this form of learning.
Konferenzberichte zum Thema "CALCULATIONS AND SIMULATIONS IN ANOTHER FORM"
1
Kurzke, Joachim. „About Simplifications in Gas Turbine Performance Calculations“. In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27620.
Der volle Inhalt der QuelleAnnotation:
Any gas turbine performance simulation tool employs simplifications, some more, some less. It depends on the intent of the simulation which simplifications are appropriate. For beginners, many are necessary for teaching how the gas turbine works from principle. For practical applications — because of the accuracy requirements — many simplifications introduced in textbooks are not appropriate. This paper comments on the simplifications that are typically made. Simplified gas property models are quite acceptable for ideal cycle analysis. For the examination of real cycles, however, especially the model of the burner should be better than those described in most textbooks. This is because these models yield the best cycle efficiency at stoichiometric fuel-air-ratio while a realistic burner model leads to the conclusion that the best thermal efficiency happens to be at significantly lower fuel-air-ratios respectively temperatures. For off-design simulations many simplifications have the aim to avoid iterative solutions or restricting the algorithms to one-dimensional iterations. If more than one iteration variable shows up — which is the case with multi-spool engine simulations — then the problem is solved with fitting several one-dimensional iterations into each other. This methodology is described in most textbooks, but it is nearly never used in industry because the logic is more complex than necessary and difficult to adapt to special needs. The seeming simplification is actually a complication when applied to real world problems. Universities should teach as a standard the multidimensional Newton Raphson iteration technique which allows writing gas turbine cycle codes with nearly no restriction to the methods of formulating the laws of physics. The consequence of simplified mathematics is often an off-design simulation which does not employ compressor and turbine maps. Such a methodology yields accurate values for thermal efficiency respectively specific fuel consumption only within a narrow range of operating conditions; the accuracy of the results is not sufficient for real world applications. Of course also in programs for industrial use the reality is modeled with many compromises. Some simplifications which have not so obvious consequences are discussed. For example, there is an influence of the speed-flow characteristics in the booster map on its operating line if an often used type of fan performance representation is employed. Another example is that an oversimplified description of what happens in the compressor interduct can lead to wrong conclusions when the effects of inlet flow distortion on the stability of compressors in series are sought.
2
von Hoyningen-Huene, Martin, und Alexander R. Jung. „Comparison of Different Acceleration Techniques and Methods for Periodic Boundary Treatment in Unsteady Turbine Stage Flow Simulations“. In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-155.
Der volle Inhalt der QuelleAnnotation:
This paper studies different acceleration techniques for unsteady flow calculations. The results are compared with a non-accelerated, fully-explicit solution in terms of time-averaged pressure distributions, the unsteady pressure and entropy in the frequency domain and the skin friction factor. The numerical method solves the unsteady three-dimensional Navier-Stokes equations via an explicit time-stepping procedure. The flow in the first stage of a modern industrial gas turbine is chosen as a test case. After a description of the numerical method used for the simulation, the test case is introduced. The comparison of the different numerical algorithms for explicit schemes is intended to ease the decision about which acceleration technique to use for calculations as far as accuracy and computational time are concerned. The convergence acceleration methods under consideration are, respectively, explicit time-stepping with implicit residual averaging, explicit time-consistent multigrid and implicit dual time stepping. The investigation and comparison of the different acceleration techniques are applicable to all explicit unsteady flow solvers. As another point of interest, the influence of the stage blade count ratio on the flow field is investigated. For this purpose, a simulation with a stage pitch ratio of unity is compared with a calculation using the real ratio of 78:80, which requires a more sophisticated method for periodic boundary condition treatment. This paper should help to decide whether it is vital from the turbine designer’s point of view to model the real pitch ratio in unsteady flow simulations in turbine stages.
3
Salomo´n, Marianne, Jens Fridh, Alexandros Kessar und Torsten Fransson. „Gas Turbine Simulations in the Computerized Educational Program CompEduHPT: Three Case Studies“. In ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38165.
Der volle Inhalt der QuelleAnnotation:
In this paper three different kinds of simulations present in the Computerized Educational Program (CompEduHPT) will be described and discussed. The main objective of these examples is to describe in detail some of the simulations and the educational aspects associated. The first example is the simulation of a Real Gas Turbine calculation procedure. CompEduHPT includes several simulations in the Heat and Power Cycles part and particularly on gas turbines. These simulations give the student an outlook of the different parameters that affect the performance based on the ideal and real approach of gas turbine’s calculation. Five simulations regarding real gas turbine calculations are included in CompEduHPT. These simulations have the purpose to show the students the different aspects, effects and results when a calculation is made considering a mixture of two ideal gases (pure air and combustion gas). At the same time they also show the improvements in the performance of the gas turbine depending on the different options available such as intercooling, reheating, regeneration and intercooling. The calculation of these cycles using an approximation to real conditions allows the students to compare with the ideal calculation process and also to compare between the different gas turbine cycles. Another example that will be explained in detail is related to turbine’s aerothermodynamic simulations. There are several simulations based on simple 2D velocity triangle theory, where not only velocities and flow angles across a turbine stage are included but also expansion, specific work, reaction, design parameters and losses. This provides the user with an easy-to-use powerful tool for understanding of the principal coupling between different parameters. By changing input values the user can visually and numerically see the effect of selected parameters. The inputs can be altered among a variety of parameters such as inlet velocity, blade speed, flow angles and turbine design parameters. The selected simulation on Aeroelasticity is one of the numerous simulations that can be found in CompEduHPT under this topic. It represents a simplified airplane wing (as flat plate), under vibration. The purpose of this simulation is to demonstrate the importance of the phase angle between the bending and the torsion branches of a coupled bending/torsion vibration. One of the main objectives of this simulation is for the students to be able to see that the value and the direction of the force for each moment are dependant on the phase lag between bending and torsion. The key issue for the students going through this simulation is to realize that if the force and the velocity have the same sign, the power is positive. On the contrary, it is negative if the signs of the force and the velocity are different. Finally, but not less important, is to observe what kind of an influence does the phase angle between bending and torsion have on the absorbed work: • If 0 < phase angle < 180 ⇒ Excitation; • If −180 < phase angle < 0 ⇒ Damping; • If phase angle = 0 or ± 180 ⇒ Neutral.
4
Pelipenko, Sviatoslav, Nicolas C. Flamant und Simon C. Impey. „Real Time Cementing Hydraulics Simulations Bring Risk Down“. In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95100.
Der volle Inhalt der QuelleAnnotation:
Abstract Proper control of downhole pressure during cementing operations is critical to maintaining well integrity, i.e. avoiding getting a well kick or fracturing the formation. Contrary to drilling operations where pressure can be monitored in real time thanks to measurement while drilling by downhole tools, no such measurements are available while cementing. Cementing operations must therefore rely on the use of simulations to estimate pressures downhole and ensure that the well integrity is not compromised. These simulations are typically performed ahead of the operations, but for critical wells it is paramount to also perform the calculations in real time to account for any deviation from the plan. We will first provide a description of the hydraulics simulator used for real time simulations. A key feature is the ability to account for fluctuations in injected fluid density, as a result of the cement slurry mixing process. This effectively results in tracking a high number of fluids with different density properties. The simulator also takes into account fluid compressibility and pressure and temperature dependent fluid viscosity, the magnitude of the effects of which we examine in application to generic field cases. Another salient feature of the simulator is its ability to determine whether fluid is lost to the formation by using flow returning from the well as an additional input. We highlight the work accomplished to achieve the performance required for real time computations and then illustrate how the simulator gets used during operation through a case study.
5
Courtin, Stéphan, Xavier Ficquet, Thi Thuy Trang Lê, Philippe Gilles und Miguel Yescas. „Residual Stress Predictions on a 29″ Narrow Gap Dissimilar Metal Weld and Comparison With a 14″ Configuration“. In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78089.
Der volle Inhalt der QuelleAnnotation:
AREVA has developed narrow gap weld techniques to perform junctions between low alloy steel heavy section components and austenitic stainless steel piping systems. In parallel, for a good understanding of welding and post weld heat treatment consequences, numerical welding simulation has already demonstrated its relevance to predict residual stress fields in welded components [1]. This paper presents Finite Element (FE) simulations of a 29″ multipass narrow gap Dissimilar Metal Weld (DMW) configuration, the welding simulation including non linear kinematic hardening models, phase transformations and visco-plastic calculations for reproducing the post weld heat treatment. The numerical results are compared to measurements obtained by the deep hole drilling technique [2]. This work gives another evidence of the relevance of the numerical welding simulation. Particularly, the comparison with a 14″ configuration [3] gives some elements to assess on the validity of both numerical and experimental techniques and on the weld thickness effect.
6
Mueschke, Nicholas J., Wayne N. Kraft, Malcolm J. Andrews und Jeffrey W. Jacobs. „Numerical Investigation of Internal Vortex Structure in Two-Dimensional, Incompressible Richtmyer-Meshkov Flows“. In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82723.
Der volle Inhalt der QuelleAnnotation:
Richtmyer-Meshkov (RM) instability occurs when one fluid is impulsively accelerated into a second fluid, such that ρ1 ≠ ρ2. This research numerically investigates RM instabilities between incompressible media, similar to the experiments reported by Niederhaus & Jacobs [1]. A two-dimensional, finite-volume numerical algorithm has been developed to solve the variable density Navier-Stokes equations explicitly on a Cartesian, co-located grid. In previous calculations, no physical viscosity was implemented; however, small scale fluctuations were damped by the numerical algorithm. In contrast, current simulations incorporate the physical viscosities reported by Niederhaus & Jacobs [1] and are explicitly used. Calculations of volume fraction and momentum advections are second-order accurate in space. Unphysical oscillations due to the higher-order advection scheme are minimized through the use of a Van Leer flux limiting algorithm. An initial velocity impulse [2] has been used to model the impulsive acceleration history found in the experiments of Niederhaus & Jacobs [1]. Both inviscid and viscous simulations result in similar growth rates for the interpenetration of one fluid into another. However, the inviscid simulations (i.e. no explicit viscosity) are unable to capture the full dynamics of the internal vortex structure that exists between the two fluids due to the absence of viscous effects.
7
Horwitz, Jeremy A. K., S. P. Vanka und P. Kumar. „LBM Simulations of Dispersed Multiphase Flows in a Channel: Role of a Pressure Poisson Equation“. In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4943.
Der volle Inhalt der QuelleAnnotation:
Abstract In recent years, Lattice Boltzmann Methods (LBM’s) have emerged as a popular class of paradigms for the simulation of multiphase flows. These methods rely on discretized Boltzmann equations to represent the individual multiphase species. Among LBM’s advantages is its ability to explicitly account for interfacial physics and its local streaming/collision operations which make it ideally suited for parallelization. However, one drawback of LBM is in the simulation of incompressible multiphase flow, whereby the density should remain constant along material characteristics. Because LBM uses a state equation to relate pressure and density, incompressibility cannot be enforced directly. This is true even for incompressible single-phase LBM calculations, in which a finite density drop is needed to drive through the flow. This is also the case for compressible Navier-Stokes algorithms when applied to low Mach number flow. To mitigate compressibility effects, LBM can be used in low Mach regimes which should keep material density variation small. In this work, we demonstrate that the assumption of low Mach number is not sufficient in multiphase internal flows. In such flows, in the absence of a Pressure Poisson constraint to enforce incompressibility, LBM predicts a compressible solution whereby a density gradient must develop to conserve mass. Imposition of inflow/outflow boundary conditions or a mean body force can ensure that mass is conserved globally, thereby quelling density variation. The primary numerical problem we study is the deformation of a liquid droplet immersed in another fluid. Though LBM is not typically conducted with a pressure Poisson equation, we incorporate one in this work and demonstrate that its inclusion can significantly lower the density variation in view of maintaining an incompressible flow.
8
Aras, Eyyup. „From Discrete Vectors to Point Sets in Machining Simulations With High-Order Tool Surfaces“. In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-13260.
Der volle Inhalt der QuelleAnnotation:
In vector based machining simulations sampling only along one direction misses surface portions, such as sharp edges and vertical walls. This drawback can be removed when sampling along multiple directions, even without increasing the number of vectors. Therefore, given the same total number of vectors, vector hits are likely to be better distributed over the surface in a multiple-rayrep model than in a single one. But in this case, although we have a better in-process workpiece representation, we face with another problem: computational expense in the vector/envelope intersections. Computations are easy when the workpiece is represented by unidirectional vectors and when the tool axis is positioned along these vectors. On the other hand, a more complicated situation occurs when the machining simulations are performed in the multiple-reyrep based environments with tools having high-order geometries. In this case, the extensive usage of nonlinear root finding algorithms makes machining simulations impractical. One solution might be to eliminate the variable representing a vector from calculations. This leads to a union of 3D-points (i.e. polyhedral, voxel and Octree representations), at the loss of accuracy. Therefore, from a geometric viewpoint we can consider the aggregate of 3D-points as a special version of the multiple-rayrep model, in which the orthogonal vectors are discretized. In this paper, first the above mentioned drawbacks are presented for the triple-vector model based environments with arbitrarily oriented tool surfaces. Later, since each NC sequence is described by using the toolpath parameter, the above problems are reduced to a single equation with collection of toolpath parameters for the given 3D-points. Since its geometric complexity is highest among other APT-type cutter surfaces, the toroidal surface is chosen for the analysis.
9
Kashinath, Karthik, Santosh Hemchandra und Matthew P. Juniper. „Nonlinear Phenomena in Thermoacoustic Systems With Premixed Flames“. In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68726.
Der volle Inhalt der QuelleAnnotation:
Nonlinear analysis of thermoacoustic instability is essential for prediction of frequencies, amplitudes and stability of limit cycles. Limit cycles in thermoacoustic systems are reached when the energy input from driving processes and energy losses from damping processes balance each other over a cycle of the oscillation. In this paper an integral relation for the rate of change of energy of a thermoacoustic system is derived. This relation is analogous to the well-known Rayleigh criterion in thermoacoustics, but can be used to calculate the amplitudes of limit cycles, as well as their stability. The relation is applied to a thermoacoustic system of a ducted slot-stabilized 2-D premixed flame. The flame is modelled using a nonlinear kinematic model based on the G-equation, while the acoustics of planar waves in the tube are governed by linearised momentum and energy equations. Using open-loop forced simulations, the flame describing function (FDF) is calculated. The gain and phase information from the FDF is used with the integral relation to construct a cyclic integral rate of change of energy (CIRCE) diagram that indicates the amplitude and stability of limit cycles. This diagram is also used to identify the types of bifurcation the system exhibits and to find the minimum amplitude of excitation needed to reach a stable limit cycle from another linearly stable state, for single-mode thermoacoustic systems. Furthermore, this diagram shows precisely how the choice of velocity model and the amplitude-dependence of the gain and the phase of the FDF influence the nonlinear dynamics of the system. Time domain simulations of the coupled thermoacoustic system are performed with a Galerkin discretization for acoustic pressure and velocity. Limit cycle calculations using a single mode, as well as twenty modes, are compared against predictions from the CIRCE diagram. For the single mode system, the time domain calculations agree well with the frequency domain predictions. The heat release rate is highly nonlinear but, because there is only a single acoustic mode, this does not affect the limit cycle amplitude. For the twenty-mode system, however, the higher harmonics of the heat release rate and acoustic velocity interact resulting in a larger limit cycle amplitude. Multi-mode simulations show that in some situations the contribution from higher harmonics to the nonlinear dynamics can be significant and must be considered for an accurate and comprehensive analysis of thermoacoustic systems.
10
Wyszkowska, Patrycja, und Robert Duchnowski. „Subjective Breakdown Points of R-estimators Applied in Deformation Analysis“. In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.250.
Der volle Inhalt der QuelleAnnotation:
This paper presents practical aspect of the breakdown point theory in deformation analysis by applying R-estimators. The main aim of the paper is to determine impact of the probability of positive (or negative) gross errors and the number of such errors on the value of breakdown point of the estimates applied. Authors consider two types of networks: a levelling network and a horizontal one. Calculations are made for two cases, namely when observations are affected by gross errors in both measurement epochs or only in the second epoch. The main results are based on the Monte Carlo method, which is a very useful tool to solve such a geodetic problem. The simulations show that the breakdown point depends on the probability of positive gross errors but also on the number of epochs in which the gross errors occur. This is especially vivid in the case of levelling networks. Another interesting finding is that even if the number of gross errors exceeds the breakdown point, we can still get reasonable results; however, not always. Thus, the paper shows the probabilities that the method breaks down for several different cases. The paper includes some numerical tests, which provided practical information about the subjective breakdown points and their importance for R-estimates applied in deformation analysis.