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(1 - 5 of 5)
- Title
- Studies of specific gene expression of phosphate transporters in sawgrass (Cladium jamaicense crantz) and cattail (Typha domingensis pers.).
- Creator
- Lin, Li, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
In the Florida Everglades, sawgrass has been displaced by cattail, predominantly resulting from phosphate enrichment. It has been found that phosphate transporters and arbuscular mycorrhizal (AM) fungi play an important role in phosphate uptake in the plants. This study aimed to reveal the symbiosis between AM fungi and sawgrass and cattail and identify the phosphate transporters, especially AM-specific phosphate transporters in these two species. AM colonization was only found in sawgrass...
Show moreIn the Florida Everglades, sawgrass has been displaced by cattail, predominantly resulting from phosphate enrichment. It has been found that phosphate transporters and arbuscular mycorrhizal (AM) fungi play an important role in phosphate uptake in the plants. This study aimed to reveal the symbiosis between AM fungi and sawgrass and cattail and identify the phosphate transporters, especially AM-specific phosphate transporters in these two species. AM colonization was only found in sawgrass roots, not cattail, at low phosphate concentrations in lab and field samples by trypan blue staining. AM fungi could increase sawgrass growth and had little effect on cattail growth. Four phosphate transporters were identified in sawgrass. CjPT1, CjPT2 and CjPT3 were expressed in roots and shoots independent of AM fungi and phosphate availability, while CjPT4 appeared to be an AM regulated phosphate transporter gene and its expression was induced by AM fungi.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/1930493
- Subject Headings
- Phosphorus, Physiological transport, Soil stabilization, Vegetation dynamics, Ecosystem management, Soil mineralogy, Plant physiology
- Format
- Document (PDF)
- Title
- Modeling of sedimentation processes in closed-end canals.
- Creator
- Li, Lin, Florida Atlantic University, Scarlatos, Panagiotis (Pete) D., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
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Due to the fact that most of closed-end canals are protected from high energy inputs, these canals tend to act as sediment traps. Accumulation of deposited material creates navigational and flood problems. Shoaling in closed-end canals is caused mostly by fine sediments. The behavior of fine sediments can be quantitatively described by means of a mass balance equation. More specifically, the advection-dispersion equation including proper sink/source terms can be used. The sink/source terms...
Show moreDue to the fact that most of closed-end canals are protected from high energy inputs, these canals tend to act as sediment traps. Accumulation of deposited material creates navigational and flood problems. Shoaling in closed-end canals is caused mostly by fine sediments. The behavior of fine sediments can be quantitatively described by means of a mass balance equation. More specifically, the advection-dispersion equation including proper sink/source terms can be used. The sink/source terms represent the processes of deposition and erosion respectively. The purpose of this thesis is to develop analytical solutions of the unsteady advection-dispersion equation as applied to free surface closed-end canals. Solutions are obtained under various initial and boundary conditions, by using the finite transformation analysis. The simulation results are validated against laboratory data.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/14757
- Subject Headings
- Sediment transport
- Format
- Document (PDF)
- Title
- Theoretical and experimental investigations of motion stability of long-span bridges in turbulent flow.
- Creator
- Li, Qiang, Florida Atlantic University, Lin, Y. K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The motion stability of long-span bridges under turbulent wind is studied. A new stochastic theory, developed on the basis of a new wind turbulence model, is applied to experimentally measured bridge deck models to determine the stochastic stability boundaries. The new turbulence model has a finite mean-square value and a versatile spectral shape, and is capable of closely matching a target spectrum, such as the Dryden or the von Karman spectrum, by changing the parameters of the model. The...
Show moreThe motion stability of long-span bridges under turbulent wind is studied. A new stochastic theory, developed on the basis of a new wind turbulence model, is applied to experimentally measured bridge deck models to determine the stochastic stability boundaries. The new turbulence model has a finite mean-square value and a versatile spectral shape, and is capable of closely matching a target spectrum, such as the Dryden or the von Karman spectrum, by changing the parameters of the model. The bridge motion is represented as a linear system of single degree of freedom in torsion. A bridge is generally subject to two types of wind loads: the buffeting loads and the self-excited loads. Only the self-excited loads are considered in the investigation, since the buffeting loads, which appear as inhomogeneous terms in the differential equation of motion, do not affect the motion stability of a linear system. In the absence of turbulence, the onset of flutter instability occurs at a critical wind velocity at which a pair of complex-conjugate eigenvalues of the combined structural-fluid system becomes purely imaginary. The corresponding eigenvectors describe the interaction between the structure and the surrounding fluid. Upon the introduction of turbulence, the composition of the structural and fluid components is changed. Since the turbulence portion of the flow fluctuates randomly in time, a new state of balance between the energy inflow from fluid to structure, and the energy outflow from structure to fluid, can only be reached in the statistical sense, or equivalently, in the sense of long-time average under the ergodicity assumption. It is the random deviation from the deterministic flutter mode that renders either the stabilizing or destabilizing effect possible. The asymptotic sample stability boundary of the motion is obtained. The aerodynamic constants for the theoretical analysis are measured experimentally in a forced vibration test conducted in a water channel, with water substituting for air as the working fluid. For a particular bridge deck model, the computed stability boundary shows that the presence of turbulence in the wind flow can be either stabilizing or destabilizing depending on the peak frequency and band-width of the turbulence spectrum.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/12324
- Subject Headings
- Bridges, Long-span, Turbulence
- Format
- Document (PDF)
- Title
- GALLOPING OF AN ELASTICALLY SUPPORTED BLUFF BODY IN TURBULENT FLOW.
- Creator
- Li, Qiang, Florida Atlantic University, Lin, Y. K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The phenomenon of flow-induced vibration is found in many engineering systems. The fluid flow generates forces on the structure that cause motion of the structure. In turn, the structural motion changes the angle of attack between the flow and the structure, hence the forces on the structure. Furthermore, turbulence generally exists in a natural fluid flow; namely, the fluid velocity contains a random part. Thus, the problem is formulated as a nonlinear system under random excitations. This...
Show moreThe phenomenon of flow-induced vibration is found in many engineering systems. The fluid flow generates forces on the structure that cause motion of the structure. In turn, the structural motion changes the angle of attack between the flow and the structure, hence the forces on the structure. Furthermore, turbulence generally exists in a natural fluid flow; namely, the fluid velocity contains a random part. Thus, the problem is formulated as a nonlinear system under random excitations. This thesis is focused on one type of motion known as galloping. A mathematical model for the motion of an elastically supported square cylinder in turbulent flow is developed. The physical nonlinear equation is converted to ideal stochastic differential equations of the Ito type using the stochastic averaging method. The probability density for the motion amplitude and the values for the most probable amplitudes are obtained for various mean flow velocities and turbulence levels.
Show less - Date Issued
- 1987
- PURL
- http://purl.flvc.org/fcla/dt/14361
- Subject Headings
- Random vibration--Mathematical models, Turbulence, Fluid dynamics
- Format
- Document (PDF)
- Title
- Design of micromixer and microfludic control system.
- Creator
- Li, Lin, Tsai, Chi-Tay, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Micromixer is one of the most significant components of microfluidic systems, which manifest essential applications in the field of chemistry and biochemistry. Achieving complete mixing performance at the shortest micro channel length is essential for a successful micromixer design. We have developed five novel micromixers which have advantages of high efficiency, simple fabrication, easy integration and ease for mass production. The design principle is based on the concept of splitting...
Show moreMicromixer is one of the most significant components of microfluidic systems, which manifest essential applications in the field of chemistry and biochemistry. Achieving complete mixing performance at the shortest micro channel length is essential for a successful micromixer design. We have developed five novel micromixers which have advantages of high efficiency, simple fabrication, easy integration and ease for mass production. The design principle is based on the concept of splitting-recombination and chaotic advection. Numerical models of these micromixers are developed to characterize the mixing performance. Experiments are also carried out to fabricate the micromixers and evaluate the mixing performance. Numerical simulation for different parameters such as fluids properties, inlet velocities and microchannel cross sectional sizes are also conducted to investigate their effects on the mixing performance. The results show that critical inlet velocities can be predicted for normal fluid flow in the micromixers. When the inlet velocity is smaller than the critical value, the fluids mixing is dominated by mechanism of splitting-recombination, otherwise, it is dominated by chaotic advection. If the micromixer can tolerate higher inlet velocity, the complete mixing length can be further reduced. Our simulation results will provide valuable information for engineers to design a micromixer by choosing appropriate geometry to boost mixing performance and broaden implicational range to fit their specific needs. Accurate and complicated fluidic control, such as flow mixing or reaction, solution preparation, large scale combination of different reagents is also important for bio-application of microfluidics. A proposal microfluidic system is capable of creating 1024 kinds of combination mixtures. The system is composed of a high density integrated microfluidic chip and control system. The high density microfluidic chip, which is simply fabricated through soft lithography technique, contains a pair of 32 flow channels that can be specifically addressed by each 10 actuation channels based on principle of multiplexor in electronic circuits. The corresponding hardware and software compose the control system, which can be easy fabricated and modified, especially for prototype machine developing. Moreover, the control system has general application. Experiments are conducted to verify the feasibility of this microfluidic system for multi-optional solution combination.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fau/fd/FA0004033
- Subject Headings
- Flow visualization, Fluidic devices -- Design, Microelectromagnetical systems, Microfluidics -- Design
- Format
- Document (PDF)
