No description available.

Root tip demography of a 43 year old Sitka spruce stand was determined over a two year period. A total of 35,300 root tips were examined. A total of 14 mycorrhizal and 4 non-mycorrhizal root tip types were recognised. One mycorrhizal type, formed by Tylospora fibrillosa, made up 67% of the root tips examined, the rest each made up less than 5% of the population. The level of infection was high, with c. 94% of the root tips infected with mycorrhizal fungi. There were marked short term fluctuations in the numbers and relative abundance of some of the types, as well as longer term, unidirectional increases in the dominant type and decreases in the numbers and relative abundance of non-mycorrhizal root tips. The effect of the addition of carbon and nitrogen was examined. Carbon addition had very little effect on the mycorrhizal population as a whole. Nitrogen, on the other hand, had a very marked effect on several of the root tip types. The relative abundance and the numbers of Tylospora fibrillosa mycorrhizas were both reduced by the addition of nitrogen, whereas the relative abundance and numbers of non-mycorrhizal tips increased. A large gradient of weight of organic matter and moisture existed on the site and this was shown to strongly influence the spatial distribution of the root tip types. Russula ochroleuca mycorrhizas were shown to have a positive association with organic matter and moisture. The occurrence of E-type mycorrhizas was negatively correlated with the accumulation of organic matter, which supports the idea that these mycorrhizas are primarily associated with mineral soil. Finally, the population structure of T.fibrillosa was examined using somatic incompatibility (SI) to determine the clone size of the fungus on the site. No SI was found between any of the isolates, even when collected 20m apart. This could mean that either T.fibrillosa does not exhibit SI or that the clone from which the isolates were collected was larger than 20m across.

This investigation studies the leakage flows over the high pressure turbine blade tip at high speed flow conditions. There is an unavoidable gap between the un-shrouded blade tip and the engine casing in a turbine stage, where the pressure difference between the pressure and the suction surfaces of the blade gives rise to the development of leakage flows through this gap. These flows contribute to about one third of the aerodynamic losses in a turbine stage. In addition they expose the blade tip to a very high temperature and result in thermal damages which reduce the blade‟s operational life. Therefore any improvement on the tip design to reduce these flows has a significant impact on the engine‟s efficiency and turbine blade‟s operational life. At the engine operational condition, the leakage flows over the high pressure turbine blade tip are mostly transonic. On the other hand literature survey has shown that most of the studies on the tip leakage flows have been performed at low speed conditions and there are only a few experimental works on the transonic tip flows. This project aims to explore the tip leakage flows at high speed condition which is the real engine condition, both experimentally and computationally and establish a comprehensive understanding of these flows on different tip geometries. The effect of tip geometry was studied using the flat tip and the cavity tip models and the effect of in-service burnout on these two tip models was established using the radius-edge flat tip and the radius-edge cavity tip models. The experimental work was carried out in the transonic wind tunnel of Queen Mary University of London and the computational simulations were performed using RANS and URANS. As the flow approached each tip model it turned and accelerated around its leading edge in the same way as the flow turns around the leading edge of an aerofoil. In the case of the tip models with sharp edges the tip flow separated at the inlet to the tip gap. For the flat tip model the flow reattachment occurred further downstream whereas in the case of the cavity tip model the length of the pressure side rim was not sufficient for the reattachment to occur and the separated flow left the rim as a free shear layer. The cavity tip model was found to have a smaller effective tip gap and hence smaller discharge coefficient in comparison to the flat tip model. For the radius-edge tip models, no separation occurred at the inlet to the tip gap and the effective tip gap was found to be the same as the geometrical tip gap. Therefore it was concluded that the tip model with radius-edges had a larger effective tip gap and hence a greater discharge coefficient than the tip geometry with sharp edges. It was observed that in the case of the supersonic tip leakage flows, decreasing the pressure ratio PR (i.e. the ratio of the static pressure at the tip gap exit to the stagnation pressure at the inlet to the tip gap) increased the discharge coefficient Cd for the tip models with sharp edges but it decreased the Cd value in the case of the tip models with radius edges. The cavity tip model with sharp edges was found to have the smallest discharge coefficient and thus the best performance in reducing the tip leakage flows as compared to all the other tip models studied in this investigation.

No description available.

In the current gas turbine market, the traditional design-test-redesign loop is not a viable solution to deploy new products within short timeframes. Hence, to keep the amount of testing to an absolute minimum, theoretical simulation tools like Finite Element Modelling (FEM) have become a driving force in the design of blades to predict the dynamic behaviour of compressor and turbine assemblies in high-speed and unsteady flows. The predictions from these simulation tools need to be supported and validated by measurements. For the past five years, Rolls-Royce Blade Tip Timing (BTT) technology has been replacing rotating Strain Gauge systems to measure the vibration of compressor blades, reducing development times and costs of new aero engine programmes. The overall aim of the present thesis is to progress the BTT technology to be applied to aero engine turbine modules. To this end, the two main objectives of this project are: i. To improve the current validated Rolls-Royce BTT extraction techniques, through the development of novel algorithms for single/multiple asynchronous and responses. ii. To validate the improved extraction using simulated and real engine test data in order to bring the Turbine BTT technology to a Rolls-Royce Technology Readiness Level (TRL) of 4 (i.e. component and/or partial system validation in laboratory environment). The methodology adopted for the development of the novel algorithms is entirely based on matrix algebra and makes extensive use of singular value decomposition as a means for assessing the degree optimisation achieved through various novel manipulations of the input (probe) raw data. The principle contributions of this thesis are threefold: i. The development of new BTT matrix-based models for single/multiple non-integral and integral engine order responses that removed certain pre-processing assumptions required by the current method. ii. The development of BTT technology to operate under the constraint of having equally spaced probes, which is unavoidable in turbines and renders current BTT methods unusable for turbine applications. iii. The development of methods for extracting measurement uncertainty and signal to noise ratios that are based solely on the raw data, without reliance on simulated reference data. Following the verification and validation of the new processing algorithms against simulated data and against validated software with numerous examples of actual engine test data, a Rolls-Royce's Research & Technology (R&T) Critical Capability Acquisition and Capability Readiness (CCAR) review has accredited the novel techniques with a TRL of 4.

This thesis describes the design of a convenient format of solid phase microextraction (SPME) for bioanalysis in pharmaceutical industry and the validation of the approach to the application. An automated in-tip SPME technique coupled with liquid chromatography (LC) and tandem mass spectrometry (MS/MS) for high throughout drug analysis has been developed and applied to the quantitative determination of various drug compounds in different biological fluids from drug discovery to clinical development. The initial research in this thesis focused on a proof-of-concept study using manual multi-fiber approach to determine a drug compound in human plasma from a clinical trial. The proof-of-concept was achieved based on the validation data and a head-to-head comparison with conventional liquid-liquid extraction (LLE) method. An in-tip SPME technique was then proposed to explore the feasibility of SPME automation and two approaches of preparing in-tip SPME fibers were developed including fiber-packed and sorbent-packed fiber preparation. A simple and high throughput in-tip SPME fiber fabricating procedure based on polymer monoliths using photo-polymerization was introduced to prepare 96 fibers simultaneously. The biggest advantage of the in-tip SPME technique is that it is simple and easy to use for automation without introducing any additional devices and in the meantime, the simplicity of SPME is maintained. Automated in-tip SPME was applied to routine drug analysis in drug discovery and development environment. One case study involved the determination of vitamin D3 in human serum with derivatization and the in-tip SPME approach was compared with traditional LLE method using either tubes or 96-well plate extraction. Another study was to use hydrophilic interaction chromatography (HILIC) –MS/MS to determine three polar compounds, imipenem (IMP), cliastatin (CIL) and -lactamase inhibitor (BLI) simultaneously in different biological fluids including rat plasma and mouse blood. The results from both studies clearly demonstrated that in-tip SPME could be used as an alternative sample preparation method in bioanalytical analysis. Matrix effects in bioanalysis using automated in-tip SPME and LC-MS/MS were then thoroughly evaluated for the first time. Our study indicated that the assumption that SPME should provide sample clean up as effective as or better than solid phase extraction (SPE) with no or minimal matrix effects might not be always true, and matrix effects should be investigated in any SPME assays in bioanalysis. Comparisons between in-tip SPME and other automated SPME approaches such as blade/thin film geometries were performed, and the advantages and limitations of using SPME versus conventional sample preparation methods including protein precipitation (PPT), LLE and SPE were summarized. Strategies for in-tip SPME method development and validation and the potential applications and future directions of in-tip SPME in bioanalysis were discussed. Finally, kinetic models were established to describe SPME extraction and desorption processes in a complex matrix with both liquid and solid fiber coatings. The models were successfully applied to different scenarios to estimate the boundary layer (BL) thickness, extraction equilibrium time and total amount of analytes extracted at a given time. The excellent agreements between the model prediction results and experimental data indicated that the SPME modeling approach had great potentials to speed up SPME method development and fiber selection.

The goal of this study is to design a new method which can be used for manufacturing the elliptic lensed fiber. The lensed fiber is obtained by heating the fiber tip in a fusing splicer at present. Before taking the fiber into fusing splicer, there are many procedures have to be checked. Those procedures will take a lot of time and increase the rate of inaccuracy. So, this research proposes a new method to form the elliptic lensed fiber by polishing. In this study, we simply use couple charge device (CCD) to detect the shape of the fiber tip. Than, we use the detected program to get the curvature of fiber tip. The system had been successfully achieved the purpose of curvature-controlled. The research will be the key technique toward the automatic bare fiber polishing system.

This study investigates the effect of chordwisely modulated tip injection on the flow and turbulence characteristics of the tip vortex through experimental measurements downstream of a rectangular half-wing that has an aspect ratio of three. This injection technique involves spanwise jets at the tip that are issued from a series of holes along the chord line normal to the freestream flow direction. The injection mass flow rate from each hole is individually controlled using computer driven solenoid valves and therefore the flow injection geometrical pattern at the tip can be adjusted to any desired waveform shape, with any proper injection velocity. The measurements are performed in a blow-down wind tunnel using Constant Temperature Anemometry and Kiel probe traverses as well as Stereoscopic Particle Image Velocimetry. Current data show consistent trends with v previously observed effects of steady uniform tip injection such as the upward and outward motion of the vortex as well as increased levels of turbulence within the vortex core. The vortex size gets bigger with injection and the total pressure levels get reduced significantly near the vortex core. The injection pattern also seems to affect the size of the wing wake as well as the wake entrainment characteristics of the tip vortex. Depending on the injection waveform pattern and injection momentum coefficient the helicoidal shape of the tip vortex also seems to get affected.

This thesis describes the design of a convenient format of solid phase microextraction (SPME) for bioanalysis in pharmaceutical industry and the validation of the approach to the application. An automated in-tip SPME technique coupled with liquid chromatography (LC) and tandem mass spectrometry (MS/MS) for high throughout drug analysis has been developed and applied to the quantitative determination of various drug compounds in different biological fluids from drug discovery to clinical development. The initial research in this thesis focused on a proof-of-concept study using manual multi-fiber approach to determine a drug compound in human plasma from a clinical trial. The proof-of-concept was achieved based on the validation data and a head-to-head comparison with conventional liquid-liquid extraction (LLE) method. An in-tip SPME technique was then proposed to explore the feasibility of SPME automation and two approaches of preparing in-tip SPME fibers were developed including fiber-packed and sorbent-packed fiber preparation. A simple and high throughput in-tip SPME fiber fabricating procedure based on polymer monoliths using photo-polymerization was introduced to prepare 96 fibers simultaneously. The biggest advantage of the in-tip SPME technique is that it is simple and easy to use for automation without introducing any additional devices and in the meantime, the simplicity of SPME is maintained. Automated in-tip SPME was applied to routine drug analysis in drug discovery and development environment. One case study involved the determination of vitamin D3 in human serum with derivatization and the in-tip SPME approach was compared with traditional LLE method using either tubes or 96-well plate extraction. Another study was to use hydrophilic interaction chromatography (HILIC) –MS/MS to determine three polar compounds, imipenem (IMP), cliastatin (CIL) and -lactamase inhibitor (BLI) simultaneously in different biological fluids including rat plasma and mouse blood. The results from both studies clearly demonstrated that in-tip SPME could be used as an alternative sample preparation method in bioanalytical analysis. Matrix effects in bioanalysis using automated in-tip SPME and LC-MS/MS were then thoroughly evaluated for the first time. Our study indicated that the assumption that SPME should provide sample clean up as effective as or better than solid phase extraction (SPE) with no or minimal matrix effects might not be always true, and matrix effects should be investigated in any SPME assays in bioanalysis. Comparisons between in-tip SPME and other automated SPME approaches such as blade/thin film geometries were performed, and the advantages and limitations of using SPME versus conventional sample preparation methods including protein precipitation (PPT), LLE and SPE were summarized. Strategies for in-tip SPME method development and validation and the potential applications and future directions of in-tip SPME in bioanalysis were discussed. Finally, kinetic models were established to describe SPME extraction and desorption processes in a complex matrix with both liquid and solid fiber coatings. The models were successfully applied to different scenarios to estimate the boundary layer (BL) thickness, extraction equilibrium time and total amount of analytes extracted at a given time. The excellent agreements between the model prediction results and experimental data indicated that the SPME modeling approach had great potentials to speed up SPME method development and fiber selection.

Thesis (M.S.)--Virginia Polytechnic Institute, 1966. / Vita. Abstract. Includes bibliographical references (leaves 39-41). Also available via the Internet.