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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Numerical Modeling on Internal Solitary Wave propagation over an obstacle using Flow-3D

Chen, Yu-Ren 19 July 2012 (has links)
Due to advances in technology and sophistication of many efficient algorithms, accurate numerical results can be achieved by using highly efficient computational software for research in wave action on coastal and harbor structures. These advances have benefitted the research in the physical phenomena of internal wave generation, propagation and breaking, which are some of the important topics in oceanography. In this study, the Flow-3D CFD (Computational Fluid Dynamics) software is used to simulate internal solitary wave motion in a density stratified fluid, in which the upper and lower layers are fresh and brine water, respectively. An internal solitary wave (ISW) is produced numerically by gravitational collapse mechanism in a numerical wave flume of 0.7 x 0.5 x 12.0 m (height x width x length ). The ISW in depression is then allow to propagate and across four different bottom obstacles (long uniform slope, trapezoidal section with short platform and isosceles triangle), in order to explore its waveform evolution and flow field distribution. This study also describes the setting and operation of the Flow-3D software, its application to the internal wave experiment, as well as verification of the numerically simulated results using previous laboratory experimental data. In this study, the lifting speed for the sluice gate was vital for not only the amplitude of an ISW, but also the speed of wave propagation in the flume. The result showed that the faster the gate opening, the faster propagation speeds and larger amplitude for the ISW so generated. Conversely, a slower gate opening led to weak wave speed and small amplitude to an ISW. Upon analyzing the results, we have found that the relationship between the speed of the gate opening and the wave propagation speed are not linear. Moreover, preliminary analysis and discussion are given for the ISW propagation over an obstacle (uniform long slope, trapezoidal section with short platform, and isosceles triangle), particularly on waveform evolution, vortex motions and flow field variations. It is believed that we can gain a better and thorough understanding of the internal wave characteristics, compared to physical laboratory experiments, if the numerical tool is applied with very fine grids and detailed analysis on the numerical outputs.
22

Laboratory Study Investigating the Three-dimensional Turbulence and Kinematic Properties Associated with a Breaking Solitary Wave

Swigler, David Townley 2009 August 1900 (has links)
A laboratory experiment was performed to investigate the three-dimensional turbulence and kinematic properties that develop due to a breaking solitary and an irregular shallow water bathymetry. A large basin equipped with a piston-type wavemaker was used to generate the wave, while the free surface elevations and fluid velocities were measured using wave gauges and three-dimensional acoustic-Doppler velocimeters (ADVs), respectively. From the free surface elevations, the evolution and runup of the wave was revealed; while from the ADVs, the velocity and turbulent energy was determined to identify specific turbulent events and coherent structures. It was found that shoaling was confined to areas with gentler sloping bathymetry near the basin side walls and the runup shoreward of the still water shoreline was not uniform. The runup was characterized by a jetting mechanism caused by the convergence of water mass near the basin centerline as the wave refracted during breaking. The jetting mechanism caused the greatest cross-shore velocities to be located near the basin centerline. The greatest turbulent events were well correlated to borefronts, resembling hydraulic jumps, where the greatest shear and fluid accelerations occurred. Because of an abrupt change in the bathymetry, a coherent structure developed which was found to have a three-dimensional flow field. It was proposed that variations in the internal flow with depth were due to the orientation of multiple vortex rings.
23

Experimental study on the propagation and reflection of internal solitary wave from a uniform slop

Chen, Hsin-hsun 10 June 2004 (has links)
Laboratory experiments were conducted to investigate the propagation of internal solitary waves on a uniform slope in a two-layered free surface fluid system. The laboratory facilities employed in this study is the first in Taiwan, which include a stainless steel wave flume (dimensions: 12 meters long with cross-section 0.5 m wide and 0.7m deep) and experimental apparatus for generating and measuring internal waves. The flume incorporates a movable vertical gate at one end for generating internal solitary waves, and a uniform slope (either £c = 30o, 50o, 60o, 90o, 120o or 130o) at the other end. The upper layer had fresh water with density £l1 (999kg/m3), to a depth H1; the lower layer was saline brine density £l2 (1030 kg/m3), which was slowly filled into the flume to a depth of H2 by gravity through several openings at the bottom of the flume, Boussinesq parameter . A mini pump was used to remove a small quantity of fresh water from one side of the vertical gate to another side. By creating a prescribed difference £bo in the interface levels on either side of the gate beforehand, internal solitary wave was generated by the mechanism of overturning the brine and fresh water behind the movable gate. Five ultrasonic probes at equidistant distance recorded the interface fluctuations, one density probe measured the change of density at the interface, while two electrical capacitance gauges for the free surface displacements likely to occur. Digital cameras were also used to record the motions of internal wave in the flume and on the slope for further analysis. Laboratory test on internal solitary wave were arranged from one of the combinations using different layer thickness ratios H1/H2, interface differences £bo, density ratios £l1/£l2, and bottom slopes £c. In addition to internal solitary wave reflection from a uniform slope, laboratory investigations included internal wave propagation on a rigid impermeable bottom and evolution on a uniform slope. Keeping the total water depth in the flume at H = 40cm, an increase in the depth parameter |H2-H1|/H produced large internal wave amplitude, reduced phase velocity, and enhanced soliton feature. From the experimental result analyzed, it suggests that the Korteweg-de Vries (KdV) theory fits solitary waves of small amplitude, and the modified KdV is suitable for large amplituded waves. Considering wave motion in an inviscid fluid, the dissipation of internal solitary waves propagating in a flume may occur through bottom friction and wave breaking. Subjected to bottom friction alone, the amplitude of most internal solitary waves in the experiments decayed approximate by 10% over a journey of 6 meters. Two types of wave breaking mechanism were found to produce strong mixing and local vortex in the fluid, causing significant energy losses. For internal solitary waves of large amplitudes, reflection coefficient for wave amplitude or energy decreased, as amplitude or energy increased. Under this condition, however, the reflection coefficient due to bottom friction may be assumed as constant. Using the experimental results obtained, empirical equation is now proposed to account for wave dissipation due to for non-breaking internal waves. The equation indicates that decrease in reflection coefficient as wave amplitude or energy increases may be expressed using a second order polynomial. Overall, experimental results suggest that good agreement can be found between experimental data and the empirical equation so derived. Upon assuming the wave reflection coefficient is solely dependent on the incoming wave amplitude or energy, prediction for reflection coefficient can be calculated in a straight forward manner. Either large-scale, high-frequency internal wave motion or internal solitary waves have been observed in natural lakes. The observed rapid decay of internal wave energy after severe breaking events seemed to be mostly due to dissipation on various sloping boundaries in a lake. From the basic laboratory experiments on internal wave reflection from various single slopes, the results many benefit provide researchers to promote further research on practical applications related to limnology.
24

Laboratory experiments on internal wave evolution on uniform slopes and topographic sills

Chen, Chen-yuan 21 January 2006 (has links)
Laboratory work were conducted to investigate the behaviors of an internal solitary wave (ISW) in a two-layer free surface fluid system in a wave flume (12m¡Ñ0.5m¡Ñ0.7m) at the National Sun Yat-sen University, Kaohsiung, Taiwan. A series of fundamental experiments on wave generation, propagation and interaction with uniform slopes and topographic features were carried out in the flume with stratified two-layer fresh/brine water. Factors governing the experiments included the thickness ratio of the upper and lower layers H1/H2, interface difference
25

study of Public-Private Partnerships poblems of outsourcing welfare solitude elder care ¡Vstudy by social exchange theory

Peng, Shu-yuan 21 June 2006 (has links)
The essence of the partnership to the government and nonprofit organization of cause in recent years changes gradually. The solitary old man in the social welfare looks after and already becomes an important subject in recent years, this research is in seven counties and cities in the south, the nonprofit organization which looks after the solitary old man is the research object, accept the parameter of the partnership between the bags outside the government, this research adopts a ripe Social Exchange Theory, SET, come to build the research way to construct a influence partnership.Use with the analytic approach of the questionnaire and return to the analytic approach, carry on analysis and way and prove. The result verifies 13 hypothesises, 10 hypothesises are supported, 3 hypothesises are not supported (1)' to the actual result of the comparative level ' could be higher than the original expectation , will determine ' believe in ' the degree; (2)' the actual result to the comparative level 's obtained, will have a apparent impact on ' partnership satisfaction '; (3) relies on the sense the government first , will just rest assured to believe in the government; (4)This ' believe in- rely on ' relation, it is the unable verify it is construct government exist at ' power ' under situation outside committee for surface; (5)It is not apparent to rely on influencing ' promise '; (6)The more great the government's ' power ' is, the more ' conflicts ' are; (7)' the conflict ' the impact on ' partnership satisfaction ' is defeated by and supports apparently relevantly; (8)Both sides ' communicate ' will contribute to setting up the one of both sides ' believe in '; (9)' common values ' construct surface is apparent to influence ' believe in ', can apparent to influence also ' promise '; (10)It is unable to prove ' the conflict ' can reduce each other ing of both sides; (11) ' believes in ' with the relation, the result is obtained and supported apparently; (12)' promise ' strong , unable to verify that the stronger ' partnership satisfaction ' is.
26

Effects of Nonlinearity and Disorder in Communication Systems

Shkarayev, Maxim January 2008 (has links)
In this dissertation we present theoretical and experimental investigation of the performance quality of fiber optical communication systems, and find new and inexpansive ways of increasing the rate of theinformation transmission.The first part of this work discuss the two major factors limiting the quality of information channels in the fiber optical communication systems. Using methods of large deviation theory from statisticalphysics, we carry out analytical and numerical study of error statistics in optical communication systems in the presence of the temporal noise from optical amplifiers and the structural disorder of optical fibers. In the slowly varying envelope approximation light propagation through optical fiber is described by Schr\{o}dinger's equation. Signal transmission is impeded by the additive (amplifiers) and multiplicative (birefringence) noise This results in signal distortion that may lead to erroneous interpretation of the signal. System performance is characterized by the probability of error occurrence. Fluctuation of spacial disorder due to changing external factors (temperature, vibrations, etc) leads to fluctuations of error rates. Commonly the distribution of error rates is assumed to be Gaussian. Using the optimal fluctuation method we show that this distribution is in fact lognormal. Sucha distribution has ""fat"" tails implying that the likelihood of system outages is much higher than itwould be in the Gaussian approximation. We present experimental results that provide excellent confirmation of our theoretical predictions.In the second part of this dissertation we present some published work on bisolitons in the dispersion managed systems. Modern communication systems use light pulses to transmit tremendous amounts of information. These systems can be modeled using variations of the Nonlinear Shrodinger Equation where chromatic dispersion and nonlinear effects in the glass fiber are taken into account. The best system performance to date is achieved using dispersion management. We will see how the dispersion management works and how it can be modeled. As you pack information more tightly the interaction between the pulsesbecomes increasingly important. In Fall 2005, experiments in Germany showed that bound pairs of pulses (bisolitons) could propagate significant distances. Through numerical investigation we found parametric bifurcation of bisolitonic solutions, and developed a new iterative method with polynomial correction for the calculation of these solutions. Using these solutions in the signal transmission could increase the transmission rates.
27

Recurrence of Solitary Fibrous Tumor of the Cervical Spinal Cord

ISHIGURO, NAOKI, MATSUYAMA, YUKIHIRO, NAKASHIMA, HIROAKI, MATSUMOTO, TOMOHIRO, SHINJO, RYUICHI, MURAMOTO, AKIO, UKAI, JUNICHI, ANDO, KEI, ITO, ZENYA, IMAGAMA, SHIRO, KOBAYASHI, KAZUYOSHI 02 1900 (has links)
No description available.
28

Genomic Characterization of Pleural Solitary Fibrous Tumours

Allo, Ghassan 11 July 2013 (has links)
Pleural solitary fibrous tumours (pSFTs) are uncommon soft tissue tumours of the pleura. that may recur and contribute to the patients’ demise. We analyzed a group of benign and malignant pSFTs for copy number alterations and for common mutations in oncogenes and tumour-suppressor genes. Malignant SFTs demonstrated more copy number alterations, especially 8q (c-myc) gain, 10q (include PTEN) loss, and 13q (Rb1) loss. Mutations were rare in this limited study.
29

Genomic Characterization of Pleural Solitary Fibrous Tumours

Allo, Ghassan 11 July 2013 (has links)
Pleural solitary fibrous tumours (pSFTs) are uncommon soft tissue tumours of the pleura. that may recur and contribute to the patients’ demise. We analyzed a group of benign and malignant pSFTs for copy number alterations and for common mutations in oncogenes and tumour-suppressor genes. Malignant SFTs demonstrated more copy number alterations, especially 8q (c-myc) gain, 10q (include PTEN) loss, and 13q (Rb1) loss. Mutations were rare in this limited study.
30

THE PHYSIOLOGICAL ACTIONS OF ADIPONECTIN IN CENTRAL AUTONOMIC NUCLEI: IMPLICATIONS FOR THE INTEGRATIVE CONTROL OF ENERGY HOMEOSTASIS

HOYDA, TED 13 April 2010 (has links)
Adiponectin regulates feeding behavior, energy expenditure and autonomic function through the activation of two receptors present in nuclei throughout the central nervous system, however much remains unknown about the mechanisms mediating these effects. Here I investigate the actions of adiponectin in autonomic centers of the hypothalamus (the paraventricular nucleus) and brainstem (the nucleus of the solitary tract) through examining molecular, electrical, hormonal and physiological consequences of peptidergic signalling. RT-PCR and in situ hybridization experiments demonstrate the presence of AdipoR1 and AdipoR2 mRNA in the paraventricular nucleus. Investigation of the electrical consequences following receptor activation in the paraventricular nucleus indicates that magnocellular-oxytocin cells are homogeneously inhibited while magnocellular-vasopressin neurons display mixed responses. Single cell RT-PCR analysis shows oxytocin neurons express both receptors while vasopressin neurons express either both receptors or one receptor. Co-expressing oxytocin and vasopressin neurons express neither receptor and are not affected by adiponectin. Median eminence projecting corticotropin releasing hormone neurons, brainstem projecting oxytocin neurons, and thyrotropin releasing hormone neurons are all depolarized by adiponectin. Plasma adrenocorticotropin hormone concentration is increased following intracerebroventricular injections of adiponectin. I demonstrate that the nucleus of the solitary tract, the primary cardiovascular regulation site of the medulla, expresses mRNA for AdipoR1 and AdipoR2 and mediates adiponectin induced hypotension. Adiponectin has electrical effects on a majority of medial solitary tract neurons and depolarizes those expressing mRNA for the hypotensive neuropeptide Y, revealing a central mechanism to modulate blood pressure. Finally, I show that adiponectin controls paraventricular nucleus neuron excitability by either inhibiting a tetraethyl ammonium-sensitive potassium current thereby depolarizing neurons or activating a glibenclamide-sensitive voltage independent potassium current hyperpolarizing neurons. Therefore, adiponectin differentially modulates potassium current to confer its central effects. These results are the first to show the physiological and electrical actions of adiponectin on individual neurons in blood brain barrier protected central autonomic nuclei. This thesis provides a framework for how adiponectin acts centrally to coordinate whole body energy homeostasis and feeding behavior in the rat. / Thesis (Ph.D, Physiology) -- Queen's University, 2009-09-15 16:50:13.933

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