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Kristiansen, Kai de Lange

Oslo Univ. (Norway). Dept. of Physics

Oslo Univ. (Norway). Dept. of Physics

AbstractAbstract

[en] Observations in the magnetic hole system under different conditions have generated many different patterns and dynamical phenomena which have generated even more ideas on how to attack and analyze them on a firm physical basis. Some of these problems are described in paper 4. In this thesis we have studied the dynamics of the few body system. The braid theory provides a compact description of this motion and enables a better real-time analysis with a minimum of information needed for computation. Also the amount of data to store on disks can then be reduced. Another aspect is that braid theory provides new topological invariants which can bring new light on the phenomena under study. The world lines from the few body system can also be closed into a knot. In knot theory several invariant quantities have been developed the last two decades, where the Jones polynomial is one powerful invariant, as pointed out in Appendix B. The diffusive processes of a few body systems can take super diffusive behaviour, as shown in paper 3. Apparently intermittent states of the same system display a large variety of different modes. By analyzing these modes using rank-ordering statistics, we find that they obey the so-called Zipf-Mandelbrot relation, as discussed in papers 1, 2, 3 and 4. Numerical calculations based on Stokes' drag and magnetic dipole-dipole interactions resemble the behaviour of the experiments well. In sections 3.2 and A.1 we presented a possible derivation of the exponent γ in the Zipf-Mandelbrot relation. The derived values of γ are within the same order of magnitude as the values of γ obtained in the experiments. However, the derived values of γ have high uncertainties. These uncertainties may be reduced with a more refined definition of the work of a mode. This refinement has to take into account the correlation between the modes. The physical meaning behind the exponent γ and the correction term ζ in the Zipf-Mandelbrot relation is not fully understood, and may also be a subject. for future studies. The diffusive behaviour of a cluster of a semi-large number spheres in a soft potential undergoes transitions in length scale from super diffusion via normal diffusion to sub diffusion. This analysis follows the motion of one sphere over a large time span. Knot theory can be used to get other measures of the collective behaviour, e.g. the linking number seems to be a promising measure and would be worth studying. This quantity represents the number of times the world lines from two spheres cross each other in a preferred direction of rotation. Random dense packing of spheres is a useful model for disordered and granular media. The monolayer of non-magnetic spheres in a ferro fluid is used to simulate this packing in 2D. Our experiments show packing structures similar to previous results. In 3D we have used a mechanical contraction method, paper 5, to simulate rapid sedimentation of binary mixture of spherical colloidal particles. The densities as function of sphere composition were found to be similar to results from the experiments. For a random dense packing it would be interesting to follow the idea of the excluded volume argument to explain quantitatively the density as function of size- and shape distributions. The mechanical contraction method seems to be ideal for doing these kinds of numerical calculations. The coordination number < C > is difficult to find in a real system of colloidal particles, but is easily obtained in numerical simulations. Nucleation of a colloidal monolayer in all alternating electric field has been studied recently. The magnetic hole system may be used to show a similar behaviour in a magnetic field. With this system we can study the nucleation process from the beginning and also to investigate the nucleation rate. Preliminary experiments have also been done that show large differences in the behaviour in systems with only free spheres and systems with some obstacles or fixed spheres among the free spheres. This can for example be used as a model for beads around a tumour cells. These beads are magnetized and conjugated with an antibody. It has been demonstrated that they can isolate tumour cells from blood, bone marrow, ascitic/pleural fluids, and enzymic-digested biopsies. A possible application for this method can be used to detect cancer cells. The order in this case results from structural correlations between dispersed spheres and ferro fluid particles rather than from macroscopic magnetostatic effects. Non-magnetic beads in a ferro fluid are likely to change its viscosity, and it would be interesting to do rheological measurements of this suspension under influence of an external magnetic field. (Author)

Primary Subject

Source

2004; 127 p; ISSN 1501-7710; ; 3 appendices, 5 papers, 204 refs., 60 figs., 15 tabs; Thesis (Dr Scient)

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Report

Literature Type

Thesis/Dissertation; Numerical Data

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Soodsakorn, A.

Department of Nuclear Technology, Chulalongkorn Univ, Bangkok (Thailand)

Department of Nuclear Technology, Chulalongkorn Univ, Bangkok (Thailand)

AbstractAbstract

[en] This thesis aims at the development of a nuclear signal transmission system using radio frequency as carrier. The system is helpful for long distance data transmission especially convenient in high level radiation area. The transmitting system comprises of pulse height ADCs with serial output, digital data modulation, frequency modulation and a l watt C B 27.125 MHz transmitter. The sequential data transmission is controlled by micro controller. The receiving system comprises of detector, noise filter and data demodulator where the signals in form of nuclear spectrum will be displayed on a micro-computer through R S-232

_{C}serial data transmission. It is found that the developed system can transmit a nuclear pulse height in the range of 0-10 V with the pulse width varying from 0.5-10 us. The linear correlation of the pulse height ADCs conversion is 0.998. The system can transmit a nuclear pulse rate of 600 cpm with the serial data of 1200 baud rate without error. At a l watt transmitted power, the system can on air cover an area of l km radius for continuous operationSecondary Subject

Source

1994; 123 p; Chulalongkorn University; Bangkok (Thailand); ISBN 974-631-076-3; ; Available from Graduate School, Chulalongkorn Univ., Bangkok (TH); Thesis (Master Eng.)

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

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Pirkle, D.R.

Wisconsin Univ., Madison, WI (USA)

Wisconsin Univ., Madison, WI (USA)

AbstractAbstract

[en] The gas flow characteristics of a novel geometry (pumped neutralizer) for decreasing the flow of gas from neutral beam neutralizers were measured and compared with a conventional (passive) neutralizer. A passive neutralizer is typically a duct attached to the ion source. For the pumped neutralizer the top and bottom surfaces of the duct are replaced by a Venetian blind geometry which opens into ball as vacuum pumping volumes. With guidance from a Monte Carlo program which models gas flow at low pressure, a one-half scale model with pumped neutralizer geometry was built and compared to a passive neutralizer with comparable dimension. With the vanes on the pumped neutralizer opened to 55 degrees, the line density of the pumped neutralizer was 1.6 times less than the passive neutralizer. The amount of gas flowing from the exit of the pumped neutralizer was from 2 to 5 times less than the amount flowing from the pumped neutralizer. Hence,the pumped neutralizer geometry appears to be a promising method of limiting the flow of gas from neutral beam gas cell neutralizers

Primary Subject

Secondary Subject

Source

1984; 159 p; Univ. of Wisconsin; Madison, WI (USA); University Microfilms, PO Box 1764, Ann Arbor, MI 48106, Order No.84-10,792; Thesis (Ph. D.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

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Reference NumberReference Number

INIS VolumeINIS Volume

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Sippel, C.

Stellenbosch Univ. (South Africa)

Stellenbosch Univ. (South Africa)

AbstractAbstract

[en] In the cascade theory of isotope separation, a set of comparisons rises with n unknowns (Gsup(i)sub(s), i=1, 2...n), which is written in matrix notation as MGsub(s) = K, where M is a n x n matrix and K is a n x 1 matrix. Usually the value of n is very big, so that numerical methods must be use to determine the unknowns Gsup(i)sub(s) (i=1,n). The rounding errors which occur in the computer calculations, cause that the numerical solutions of the equations are sensitive to the numerical method which is used for the calculations. The stability or unstability of numerical methods is often describe in terms of the eigenvalue of the involved matrix. This thesis deals with techniques that are used in the analysis of eigenvalues of a matrix with parameters and this techniques are implemented in the cascade theory

Original Title

Spektraalanalise van matrikse met parameters

Primary Subject

Secondary Subject

Source

Mar 1985; 106 p; Available from the Registrar, University of Stellenbosch, Victoria Street, Stellenbosch, 7600, South Africa; Thesis (M.Sc.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

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Pijnappel, W.W.F.

Technische Univ. Delft (Netherlands)

Technische Univ. Delft (Netherlands)

AbstractAbstract

[en] One aim of this thesis is to point out the advantages of quantifying (estimating) NMR model parameters directly in the measurement (time) domain, rather than to first transform the data to the frequency domain and carry out the quantification there. Advantages mentioned are: 1. The distribution of sampling times may be arbitrary. It suffices to provide a list of those times at which data points are available. In principle one can calculate the distribution that yields the best overall result. 2. Point 1. implies that truncation of data points does not entail corrections. This in turn implies that the disturbing influence of a broad, non-descript background line can be reduced simply by discarding initial data points. In addition, a measurement may be ended before the signal has decayed into the noise. The latter is important for reducing the time of multidimensional measurements. 3. If the available data points have been sampled at uniformly spaced times, then black-box quantification methods that save human involvement can be used. If, in addition, the exponentially damped sinusoid model function can be entertained, then the computational cost of interactive time domain quantification can be reduced by a factor of several tens. A number of applications of both black-box and interactive quantification methods has been given. The results supported the above points 2 and 3. Subsequently, there are two aspects common to both the time and the frequency domain. First, significant improvement can be achieved by imposing prior knowledge. In this thesis prior knowledge of the phases of the sinusoids was imposed. Second, the quantification may be hampered by lack of knowledge about the model function. In the time domain this problem can be alleviated by expanding an unknown form into a sum of exponentially damped sinusoids with the aid of HSVD. In the frequency domain a partial solution may be achieved by integration of an unknown shape. Note however that use of so-called 'natural lineshapes', derived from high-SNR reference data, may be a viable alternative in some circumstances. (author). 137 refs.; 19 figs.; 7 tabs

Primary Subject

Source

5 Feb 1991; 130 p; Photo-copies available from Library KNAW; P.O. Box 41950, 1009 DD Amsterdam, The Netherlands (MON 38270); This investigation is part of the research program of the Foundation for Fundamental Research of Matter (Stichting Fundamenteel Onderzoek der Materie FOM), which is financially supported by the Netherlands Organization for Pure Scientific Research (Nederlandse Organisatie voor Zuiver Wetenschappelijk Onderzoek ZWO); includes summary in Dutch.; Proefschrift (Dr.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

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Seburn, D.C.

Alberta Univ., Edmonton, AB (Canada). Dept. of Geography

Alberta Univ., Edmonton, AB (Canada). Dept. of Geography

AbstractAbstract

[en] A study was undertaken to examine the effects of an experimental (20 bbl) crude oil spill on a right-of-way in a black spruce forest underlain by permafrost, near Fort Norman, Northwest Territories. The spill was designed to simulate a leak from a belowground pipeline, and three environments were examined: the forest, right-of-way (ROW), and trench. The mean maximum thaw depths of all environments significantly increased after the spill. The greatest increases were experienced in the undisturbed forest (150%) and moderately disturbed ROW (75%). Microclimatic data indicated that complete freeze-back occurred in even the deepest layer of the unoiled areas. Cuttings of salix arbusculoides planted in oiled areas three years after the spill fared better or no worse than cuttings planted in unoiled areas. Survival was as high as 75% at the end of the growing season but declined to less than 15% by the end of the winter. Rooting success indicated that potential survival could be as high as 61%, making this a valuable revegetation species for subarctic oil spills. The number of species or species assemblages present declined significantly only on the heavily oiled ROW, where total plant cover declined by ca 80%. Nineteen species or assemblages out of 34 significantly declined after the spill. Six species increased in abundance after the spill, half of which were grasses or sedges. 15 refs., 38 figs., 37 tabs

Primary Subject

Source

Aut 1993; 164 p; Univ. of Alberta; Edmonton, AB; ISBN 0-315-88156-9; ; MF Micromedia Ltd., 240 Catherine Street, Suite 305, Ottawa, Ontario, Canada K2P 2G8 $15 CAN; Thesis (M.Sc.).

Record Type

Book

Literature Type

Thesis/Dissertation; Numerical Data

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Kawano, L.

Fermi National Accelerator Lab., Batavia, IL (USA)

Fermi National Accelerator Lab., Batavia, IL (USA)

AbstractAbstract

[en] The evolution of domain walls in the early universe is studied via 2-D computer simulation. The walls are initially configured on a triangular lattice and then released from the lattice, their evolution driven by wall curvature and by the universal expansion. The walls attain an average velocity of about 0.3c and their surface area per volume (as measured in comoving coordinates) goes down with a slope of -1 with respect to conformal time, regardless of whether the universe is matter or radiation dominated. The additional influence of vacuum pressure causes the energy density to fall away from this slope and steepen, thus allowing a situation in which domain walls can constitute a significant portion of the energy density of the universe without provoking an unacceptably large perturbation upon the microwave background

Primary Subject

Source

Oct 1989; 30 p; NASA-CR--186076; NAS--1.26:186076; FERMILAB-PUB--89/208-A; NTIS, PC A03/MF A01; Ph.D. Thesis - Chicago Univ.

Record Type

Report

Literature Type

Thesis/Dissertation; Numerical Data

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Sukaravan, P.

Department of Nuclear Technology, Chulalongkorn Univ., Bangkok (Thailand)

Department of Nuclear Technology, Chulalongkorn Univ., Bangkok (Thailand)

AbstractAbstract

[en] The principle of density determination by nuclear method is to measure scattered rays from materials and calculate density from regression equation of the relation between scattered rays and known density. In this research, fourteen kinds of materials are sand, gravel, three kinds of stone, cement, lime, concrete, alloy-dust, rice chaff, sae-dust, lignite, organic fertilizer and pure water are used. These materials are low porosity type and high porosity type. In this study it was found that the amount of scattered rays and density of materials had good relation only in case of low porosity type. The regression equation from this experiment can be used to determine the density of materials in range of 1.00 - 2.59 gm/cm

^{3}, and after testing with known material densities the errors are in the range of 0.68 - 7.80 %. The nuclear equipment system was also designed for the determination of density on the surface of materials to use in laboratory and in the fieldSource

1978; 101 p; Chulalongkorn Univ; Bangkok (Thailand); Available from Graduate School, Chulalongkorn Univ., Bangkok (TH); Thesis (Master Eng.)

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

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Stojkovski, Valentino

Faculty of Mechanical engineering, St. Cyril and Methodius University, Skopje (Macedonia, The Former Yugoslav Republic of)

Faculty of Mechanical engineering, St. Cyril and Methodius University, Skopje (Macedonia, The Former Yugoslav Republic of)

AbstractAbstract

[en] A two-component flow with a low concentration occurs in the freeboard after the eruption of the bubbles at the free surface of the bubbling fluidized beds. A three-dimensional mathematical model of gas-particle mixture turbulent flow is developed in this work. The gas turbulence is modeled using standard k-ε turbulence model. The dispersed phase is treated by the Lagrangian approach. Coupling between the gas phase and the dispersed particles is modeled by adding, source term in the momentum equation for gas phase. By using the equation for determining the drag coefficient, the particle's shape is involved in the model, as well. Experimental investigations for determining the conditions at the bed surface, the origin of erupting bubbles and their erupting mechanism and for selecting dominant influencing parameters are done. Comparisons of the experimentally obtained results with the results of other authors, which are in reasonable agreement, are used for determining the dominant influencing parameter related to the phenomena of bursting bubbles. On a base of observation, the dynamic eruption mechanism of single bursting bubble is proposed. This bubble eruption mechanism is used like a boundary condition in the numerical experimentation for investigation of the entrainment of particles and its separation along the freeboard height. The numerical solving of the developed mathematical model is accomplished by using the CFD technology. For graphical design and mesh generation of the flow domain and for numerical solving of the equations of the developed mathematical model, the software packages Gambit and FLUENT are used, respectively. The testing and verification of the proposed erupting bubble mechanism and the developed mathematical model for two-component flow in the freeboard, is made by numerical experimentation in 3D cylindrical flow domain, in the following conditions: eruption of isolated central bursting bubble; determining of particles terminal velocity; determining the entrainment and elutriation rate of total mass flux; comparison of the granular composition of the entrainment material. In all phases of testing the models, good agreement between numerically and experimentally results are obtained. hose facts confirm the consistency of the developed mathematical model for particles entrainment in the freeboard of bubbling fluidized bed. (Author)

Original Title

Matematichki model na mehanizmot na iznesuvanje chestici od meurest fluidiziran sloj vo slobodniot prostor nad slojot

Primary Subject

Source

12 Nov 2001; 268 p; Available from the National and University Library 'Kliment Ohridski', Skopje, Macedonia; 345 refs., tabs., figs.; Thesis (Ph.D.)

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Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

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Shrieve, D.C.

California Univ., Berkeley (USA)

California Univ., Berkeley (USA)

AbstractAbstract

[en] The purpose of this study was to characterize a model system in which to study hypoxic cell biology in vitro as a function of time under growth and metabolism resulting from prolonged hypoxia affect cellular radiation sensitivity. EMT6/SF cells were grown in monolayers on glass 60 mm petri dishes that had been modified to permit the addition of hypoxic solutions of test drugs or radiolabeled compounds without breaking the system open to air. These dishes were then sealed in aluminum chambers that were evacuated and re-filled eight times with 95% nitrogen/5% carbon dioxide (O

_{2}< 10 ppm). EMT6/SF cells that were maintained at 37 C under hypoxic conditions showed no increase in cell number for up to 70 h. The mitotic index of hypoxic cultures was less than 0.1%, compared to 2.3-3.0% in aerated cultures. The plating efficiency of hypoxic cells decreased with time to 20-30% of control values by 70 h. Aerated cultures consumed glucose more rapidly than hypoxic ones, but, on a per cell basis, hypoxic and aerated cells consumed glucose at equal rates (ca. 1.2 x 10^{-4}μg/cell/h). Virtually 100% of the glucose consumed was converted into lactic acid in both aerated and hypoxic culturesPrimary Subject

Source

1982; 132 p; University Microfilms Order No. 83-00,654; Thesis (Ph. D.).

Record Type

Report

Literature Type

Thesis/Dissertation; Numerical Data

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