Spelling suggestions: "subject:"ffa"" "subject:"afa""
1 |
Theoretical study of non-relativistic electron dynamics under intense laser fieldsLong, Zijian January 2012 (has links)
Strong field approximation (SFA) is the most important approximation
in the analytical theory of intense laser matter interaction. Based
on SFA many analytical theories have been developed such that a
broad spectrum of strong field physics phenomena can be described.
The central idea of SFA-based theories is to approximate the
electron propagation in the continuum by the Gordon-Volkov
wavefunction - a well studied analytical solution to the time-dependent Schr\"{o}dinger equation where the electron is driven by the
laser field only. This approximation captures some of the essential
features of strong-field physics, but at the same time causes several problems in the theory.
In this thesis a comprehensive study of the SFA has
been presented. We introduce the SFA in both the length gauge and the
velocity gauge. The adequacy of SFA has been discussed by comparing the theory to the numerical solution to
the time-dependent Schr\"{o}dinger equation (TDSE). The numerical method of solving TDSE is
presented as a separate chapter.
In order to obtain a better
understanding of the applicability of SFA-based theory, we tested the major approximations in the theory by using
three different models: the zero-range potential, the hydrogen atom and
the hydrogen molecular ion. The accuracy of the method of steepest descent (MSD)
and other major approximations in the analytical theory have
also been examined. Targeting at the generalization of
the SFA-based theories, several extensions and improvements of SFA
have been proposed. We will review them in detail and bring them
into unity.
One of the most successful aspect of the SFA-based theories is to
describe and decompose electron dynamics into components such that
identification of different physical processes becomes possible. For
instance, the direct ionization and non-sequential double ionization
bear clear definitions only within the SFA-based framework. The
physical interpretation becomes more straight forward due to the
fact that there is a close connection between the quantum orbital
and classical trajectory. The MSD is a
mathematical tool to bridge the quantum orbital and the classical
trajectory in an SFA-based theory. We will discuss MSD within a
systematic framework so that the higher order asymptotic expansion
terms can be obtained in a straight forward way.
After gaining substantial understanding of the SFA and the MSD we developed
a graphic user interface (GUI) software that is capable of
calculating strong field ionization rates, photo-electron spectra
and high harmonic generation spectra. The software interface and
algorithms have been presented in the thesis. Sample calculations
were done and compared with the previously obtained results.
In the last chapter of the thesis, we further developed the theory to
describe a two-laser ionization scheme where one laser is chosen
to be resonantly coupled two real states and the other is a strong
few-cycle laser pulse. We demonstrate the periodic dependence of the
total ionization on the appearance time of the strong few-cycle
laser pulse. In the case of few-cycle pulses with lower intensity,
we observed side-bands in the photoelectron spectrum, whose
intensity vary periodically with the appearance time of the pulse.
We show that our extended theory is able to explain these phenomena
adequately.
|
2 |
Probing the Molecular Interactions of an Asphaltene Model Compound in Organic Solvents and Aqueous Solutions by Surface Forces Apparatus (SFA)Wang, Jing Unknown Date
No description available.
|
3 |
Theoretical study of non-relativistic electron dynamics under intense laser fieldsLong, Zijian January 2012 (has links)
Strong field approximation (SFA) is the most important approximation
in the analytical theory of intense laser matter interaction. Based
on SFA many analytical theories have been developed such that a
broad spectrum of strong field physics phenomena can be described.
The central idea of SFA-based theories is to approximate the
electron propagation in the continuum by the Gordon-Volkov
wavefunction - a well studied analytical solution to the time-dependent Schr\"{o}dinger equation where the electron is driven by the
laser field only. This approximation captures some of the essential
features of strong-field physics, but at the same time causes several problems in the theory.
In this thesis a comprehensive study of the SFA has
been presented. We introduce the SFA in both the length gauge and the
velocity gauge. The adequacy of SFA has been discussed by comparing the theory to the numerical solution to
the time-dependent Schr\"{o}dinger equation (TDSE). The numerical method of solving TDSE is
presented as a separate chapter.
In order to obtain a better
understanding of the applicability of SFA-based theory, we tested the major approximations in the theory by using
three different models: the zero-range potential, the hydrogen atom and
the hydrogen molecular ion. The accuracy of the method of steepest descent (MSD)
and other major approximations in the analytical theory have
also been examined. Targeting at the generalization of
the SFA-based theories, several extensions and improvements of SFA
have been proposed. We will review them in detail and bring them
into unity.
One of the most successful aspect of the SFA-based theories is to
describe and decompose electron dynamics into components such that
identification of different physical processes becomes possible. For
instance, the direct ionization and non-sequential double ionization
bear clear definitions only within the SFA-based framework. The
physical interpretation becomes more straight forward due to the
fact that there is a close connection between the quantum orbital
and classical trajectory. The MSD is a
mathematical tool to bridge the quantum orbital and the classical
trajectory in an SFA-based theory. We will discuss MSD within a
systematic framework so that the higher order asymptotic expansion
terms can be obtained in a straight forward way.
After gaining substantial understanding of the SFA and the MSD we developed
a graphic user interface (GUI) software that is capable of
calculating strong field ionization rates, photo-electron spectra
and high harmonic generation spectra. The software interface and
algorithms have been presented in the thesis. Sample calculations
were done and compared with the previously obtained results.
In the last chapter of the thesis, we further developed the theory to
describe a two-laser ionization scheme where one laser is chosen
to be resonantly coupled two real states and the other is a strong
few-cycle laser pulse. We demonstrate the periodic dependence of the
total ionization on the appearance time of the strong few-cycle
laser pulse. In the case of few-cycle pulses with lower intensity,
we observed side-bands in the photoelectron spectrum, whose
intensity vary periodically with the appearance time of the pulse.
We show that our extended theory is able to explain these phenomena
adequately.
|
4 |
A Study of Interactions of Asphaltenes in Organic Solvents Using Surface Forces ApparatusXie, Jinggang 06 1900 (has links)
A Surface Forces Apparatus (SFA) was used in this study to investigate the fundamental surface forces in oil sand processing research. Asphaltene coated surfaces were chosen as the research topic due to the critical role of asphaltenes in oil sands processing, from bitumen extraction, froth treatment to tailings treatment.
To mimic the real surface state in industry processing, dip-coated asphaltene surfaces were prepared for surface force experiments. In this study, a SFA 2000 was used to determine intermolecular and surface forces of asphaltene in organic solvents (toluene and heptane). The force vs. distance curves, or so-called force profiles obtained provide valuable information on local material properties such as interaction energies, molecular conformation changes of the interacting asphaltene surfaces or films. Atomic force microscopy (AFM) was used to provide complementary information on the surface morphology of the prepared asphaltene surfaces. / Chemical Engineering
|
5 |
Material flow analyses in technosphere and biosphere – metals, natural resources and chemical productsPalm, Viveka January 2002 (has links)
No description available.
|
6 |
An Analysis on the Efficiency of Land Administration Offices after computerization in Kaohsiung Area: Application of DEA and SFAHo, Chin-yun 21 August 2008 (has links)
Local land administration office is to execute registering of lands and buildings. Its
objective is to implement local land policy. In the mean time, its functions are about
citizen¡¦s property rights. Because the social, economy and political environment have
been changed rapidly, demands for land administration and service quality have been
growing as well. Therefore, the first priority work for government is to improve whole
administrative efficiency and effectiveness, by using modern technology. It thus needed
to electronic-wise land office, to set up a computerization system of land information
management so as to provide complete land information, to execute modern
administration, to promote competition, and to provide convenient and efficient services.
Therefore, the purpose of this study is to research these first-line local offices so as (i) to
promote its efficiency after being computerized (ii) to compare the implementing result
before and after the computerization in Kaohsiung county and city, and (iii) to study the
influences of the computerized process, finally (iv) to suggest local offices decision
makers the future direction of improvement.
This study uses DEA and SFA to compute their efficiency after computerization of
the local land offices in Kaohsiung county and city. To do this, we collect annually
statistics and use DEA-Solver software and Frontier 4.1 computer program to evaluate
their productivities, and to make an efficiency analysis. The results revealed that the
annual average technology efficiency descended before computerization and ascended
after computerization for all land offices. CCR model revealed that annual averages of
technology efficiency are stable before computerization and it ascended after
computerization for all land offices. SFA analysis revealed that annual averageefficiency score slightly ascends before computerization and ascends after
computerization except for year 2001. For technology changes, their productivities
slightly descends for all land offices in Kaohsiung county but ascends for all land
offices in Kaohsiung city. For efficiency slack analysis, all five land offices must
reduce their inputs in Kaohsiung county. For output slack, only Chi-Shang land office
must expand its output 13.01% so as to reach a relatively inefficient DMU. Between
the Kaohsiung county and city, information difference between city and country has
influences on efficiency. Land offices in Kaohsiung city have general higher average
technology efficiency than those in Kaohsiung county.
This study uses DEA and SFA to analyze land offices in Kaohsiung county and city,
and it was found that whole efficiency scores increased after computerization. And it is
suggested several important problems and the possible directions of productivity
improvement in the future for all land offices.
|
7 |
Material flow analyses in technosphere and biosphere – metals, natural resources and chemical productsPalm, Viveka January 2002 (has links)
No description available.
|
8 |
A Study of Interactions of Asphaltenes in Organic Solvents Using Surface Forces ApparatusXie, Jinggang Unknown Date
No description available.
|
9 |
Vliv přídavku oleje do krmiva modelového organismu na zastoupení mastných kyselin ve vybraných tkáníchKaňoková, Linda January 2019 (has links)
The Master's thesis deals with the effect of feed enrichment with various types of oils on the deposition of fatty acids in selected tissues. Forty male Wistar Albino rats were divided into four groups and fed for 10 weeks daily ad libitum with a basic feed mixture enriched with 8 % palm, 8 % safflower, 8 % fish oil or 8 % microalgae Schizochytrium sp. oil. Rats had also free access to the drinking water. Fat from the tissue samples (liver, muscle, visceral fat) was extracted, converted to methyl esters and analyzed with usage of gas chromatography. The results of the experiment show that the addition of various types of oils to the feed of model organism can influence the deposition of fatty acids in its tissues. The addition of fish oil and microalgae Schizochytrium sp. oil caused statistically significant decrease (p < 0,05) in the ratio of PUFA n-6/n-3 in all observed tissues to a value of 1 or less compared to the addition of palm and safflower oil. Low ratio of n-6/n-3 polyunsaturated fatty acids is considered to be more desirable in reducing the risk of cardiovascular diseases.
|
10 |
Directly Measuring the Adhesive and Elastic Properties of Bacteria using a Surface Force ApparatusHeo, Cheol Ho January 2006 (has links)
Bacterial adhesion is the first step of biofilm formation that plays various roles in the environment and the human body. Examples of undesirable roles of biofilm formation include metal rust, sewage sludge and bacteria-related diseases. Desirable roles are biofiltration and bioremediation.For a decade, Atomic Force Microscopy (AFM) has been the primary tool used to study the adhesion and elastic properties of individual bacteria. In this work we show it is possible to use a Surface Forces Apparatus (SFA) to measure elastic and adhesive properties of small collections of surface bound bacteria. The measurements are conducted with incomplete, patterned bacterial films and we have developed a protocol to image the contact area with AFM after the experiment. Using the SFA, we measured the force profile between a P. Aeruginosa PAO1 film and a bare mica surface. We repeated the measurement in the same contact position for up to ten days to determine the effect of desiccation on the film material properties, and then moved to the new contact area to measure the film thickness and elastic properties. A large shrinkage of the bacterial film thickness was measured during the first few days due to the bacterial film desiccation and rearrangement. The proportion of shrinkage depends on factors such as the bacterial film coverage, roughness, temperature and relative humidity. Thickness compressibility was estimated from the force curves. As a force approximation, the stress at the center of the contact (&#963;) and the area of the contact were estimated by applying the Hertz model. Since the film is incomplete the calculated area in contact was reduced by a factor estimated from the optical image of the contact zone. Adhesiveness was measured in receding force profiles. Maximum adhesive force was detected in the first day, due to the high capillary force, decreased by the bacterial film desiccation and increased again due to the conditioning film.
|
Page generated in 0.038 seconds