Surface metrology has been widely used in manufacturing for many years. There has been a wide range of techniques applied for measuring surface topography. A photometric stereo technique is one of the best ways for the analysis of three-dimensional (3D) surface textural patterns. Many published works are concerned the developed approach for recovering the 3D profiles from surface normal. This research not only presents a methodology used to retrieve the profiles of surface roughness standards but also investigates the uncertainty estimation of textural measurement determined by the photometric stereo method. Various input quantities have been studied such as pixel error from recovered 3D surface textural patterns, the power of light source which involved with surface roughness average (Ra) value and the effect of room temperature. The surface roughness standards were utilized as the reference value. In term of increasing accuracy of the reference value, a contact method (stylus instrument) was used to calibrate them. Illumination angles of light source had some influence on the measurement results. A coordinate measuring machine (CMM) was used for holding the light source in order to study the effects of tilt and slant angles. The effect of tilt and slant angles were investigated. The results of these experiments successfully indicated that the angle used in photometric stereo method played an important role to the accuracy level of the roughness measurement results. The surface roughness specimen manufactured by a Computer Numerical Control (CNC) was applied to validate the capability of the photometric stereo system.

Occult deposition is the direct uptake of cloudwater by vegetation that comes into physical contact with wind-driven cloud droplets. This can be a significant pathway for hydrological and chemical fluxes from the atmosphere to some forests. Methods for estimating cloudwater fluxes to forests are reviewed. Previous studies have neglected the fact that cloudwater is not a conservative atmospheric quantity. This invalidates traditional micrometeorological approaches for estimation of cloudwater fluxes to forests. A theory is developed to predict the change in the cloudwater flux with height due to condensation in the updrafts of orographic cloud, allowing estimation of surface uptake via eddy correlation measurements while accounting for condensation. The performances of three microphysical instruments are examined. From collocated measurements, errors in cloud liquid water content are determined for a Particulate Volume Monitor (PVM) and a Forward Scattering Spectrometer Probe (FSSP) to be less than 0.01 g m⁻³ and 0.035 g m⁻³ respectively. Similarly, the error bounds for surface-normal cloud liquid water fluxes are found to be 2 mg m⁻² s⁻¹ for the PVM and 3.5 mg m⁻² s⁻¹ for the FSSP. Smaller errors are found to be associated with the uncertainty in the direction of the flux relevant to surface uptake. The FSSP is seen to have larger errors when droplet concentrations exceed 600 cm⁻³. A vertical divergence is detected in the cloudwater flux; the downward flux decreases with increasing distance from the surface, usually changing sign by 15 m above ground. Five candidate processes are identified as possible explanations for this measured flux divergence. A scale analysis shows that the liquid water source (condensation due to pseudoadiabatic ascent) is largely responsible for the change in flux with height. Accounting for the change in flux with height results in a near doubling of the estimated surface flux relative to the flux measured at a height of 10 m in the surface layer for this silver fir forest. This factor applies to chemical as well as liquid water fluxes. This source of liquid water also is seen to be important in developing a simple model for cloudwater deposition. / Graduation date: 1997

In 1996, Beach et al. first proposed the idea of mounting an echo-sounder on a Waverunner to measure nearshore beach profiles. This thesis discusses the Coastal Profiling System, an extension of the original work, which has been utilized to measure nearshore bathymetry at selected sites along the coasts of North Carolina, Oregon, and Washington. Position of the Coastal Profiling System is accurately measured five times per second using a differential global positioning system (DGPS), while depth below the hull is measured by an acoustic echo-sounder. Surveys can be conducted in waves up to 3 m and in depths of 1-15 m. The effects of waves, tides, and set-up are eliminated by the co-collection of position and depth data. In October 1997, extensive testing of the system took place at the SandyDuck '97 field experiment in Duck, NC. Nearshore bathymetric surveys were taken simultaneously by the Coastal Research Amphibious Buggy (CRAB) and the Coastal Profiling System (CPS). Comparison of the CPS with CRAB measurements interpolated to the same locations showed a mean bias of 4.6 cm too shallow in the vertical and standard deviations about the bias of 5.5 cm. The largest differences occur over the steeply sloping flanks of sand bars. The bias statistic, of central interest to these tests, is confused by the potential of boat tilt and by possible errors in the CRAB data itself. In July & August 1998, the system was tested as a tool for long-term coastal monitoring by the Southwest Washington Coastal Erosion Study in a regional morphology monitoring program (Ruggiero et al., 1997). A 2-3 km section in approximately the center of each of the four sub-cells of the Columbia River littoral cell, and an anomalous fifth site, was surveyed to map the morphology of each region. Alongshore-averaged profiles were decomposed into underlying AX[superscript m] profiles and deviations from this equilibrium profile. The mean of the exponents was close to 2/3 with m=0.70, but ranged between sites from 0.56 to 0.79. Shape parameters between 0.027 and 0.038 were estimated. Nearshore slopes (0-1 km cross-shore) were calculated from the exponential profile in the dissipative range with a minimum of 0.0067 and a maximum of 0.0089. However, no correlation was seen between the shape parameters and the 1 km nearshore slopes. An analysis of the deviations of the alongshore-averaged profiles from the equilibrium profile provided an objective method to determine sand bar positions from zero-down-crossings. Each site was characterized by a minimum of two sand bars in 2-6.5 m (NAVD 88) depths with heights of 0.2-2 m, lengths of 164-949 m and volumes of 48-534 m��/m. An additional bar in the swash zone between the +1 m elevation and 1 m depth contour was resolved in some cross-shore profiles. The crest of the bar largest in height was located at 3-4.5 NAVD 88 m at four of the five sites suggesting the profiles vary on similar cross-shore length scales amongst the sub-cells. A series of surveys in April, June, and October 1998 at the northern most site in Ocean City, WA demonstrated onshore bar migration and seaward accretion of the foreshore. This seasonal response was further quantified between August and October at Fort Canby. Three nearshore profiles surveyed by Willard Bascom et al. (1954) in the 1940s were reoccupied to compare the shape of the morphology 50 years ago to present. These profiles demonstrate accretion of approximately 2 m elevation gains in the nearshore and 26-165 m of shoreline change. Although the Coastal Profiling System is a highly accurate, mobile and efficient method to obtain nearshore profiles, several improvements have been suggested. Future modifications to the system should include an increase in the precision of the echo-sounder measurements, higher sampling rates, and improvement of the user interface. Additional components may include an onboard navigation system, a thermister to measure temperature and salinity, and a motion sensor to measure roll and pitch of the vehicle. / Graduation date: 1999

Graduation date: 1998

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To augment the monitoring capabilities of a Balzers 760 coating chamber, we replaced the simple, single wavelength optical monitor with a wide-band scanning monochromator system which records transmission data over the visible region of the spectrum. The system is controlled by an IBM-PC. The same computer is also interfaced to a quartz crystal monitoring system which was purchased with the Balzers chamber. The scanning monochromator system required a new brighter light source to deliver sufficient signal to the detector array through the more complex, dispersive optical train. Above the chamber the filter and the photomultiplier pair were removed, and replaced by a flat mirror which diverts the beam horizontally into the scanning monochromator system. The beam passes first through a telescope-slit configuration onto a Jobin-Yvon holographic grating, built to disperse the 400-800 nm band of which we use approximately 360 nm. This reflective grating images the spectrum of the slit onto a Fairchild CCD array, which consists of 1728 elements. These elements are then averaged into 173 data points and recorded by the IBM-PC. The 173 data points allows us a wavelength resolution of about 2 nm. The IBM incorporates a Tecmar A/D board in accepting data from both the quartz crystal monitor and the scanning monochromator system. Although the system is capable of recording data at a faster rate, it is generally stored once every three seconds. This is adequate since at normal deposition rates this gives us information every 10 - 20 Angstroms of deposited material. The system has been used in several applications which will be discussed in this dissertation. They include in situ measurements of water adsorption into a film, derivation of optical constant profiles during the film deposition, both of which may lead us to a better understanding of the growth of a thin film. The monochromator has also been used to analyze the components of a multilayer coating by monitoring the film's transmission spectra while it was sputter-etched off. The extension of the system into the ultraviolet region of the spectrum and some future applications are also considered.

The Linear Voltage Differential Transformer (LVDT) is an accurate sensor for stem diameter measurements. Based on the results of this dissertation it was found that stem diameter [mm] was related to water content [grams] of the cotton crop by the following equation: W(D) = 0.114(D)³ˑ¹⁸² Also the ratio of stem diameter contraction rate to the rate of water loss in cotton was experimentally determined to be: (dW/dt)/(dD/dt) = (0.166 [g min⁻¹])/(0.535 [μm min⁻¹]) = (.0469% per minute)/(.0039% per minute). Similarly the cellular water potential was derived to be a non linear function of stem diameter in cotton: ψ(t) - ψₒ = 2 ε ln (D(t)/ Dₒ) + πₒDₒ² [(1/D²(t)) – (1/Dₒ²)]. Based on this work, the grower can estimate the water content, transpiration rate and water potential of the cotton crops via stem diameter measurements. Moreover, a computer system can be implemented to remotely keep track of the water status of the field, and control the irrigation system. A general model was proposed to quantify the nature of input-output relation of the cotton crop. A proposed simplified model based on stem diameter is also introduced. The stem diameter measurements can be used as an index for estimation of cotton's water content, transpiration rate, and water potential. These three parameters and the proposed simplified model established a plant based predictive irrigation scheduling technique. The electrical output of the LVDT was quite noisy. To remove the noise and demodulate the data, two cascade circuits were designed and implemented. First, the external output circuit removed the noise and isolated the LVDT. Second, the LVDT signal conditioner demodulated the phase information from the secondary windings which were produced by the movement of the rod. By the implementation of these circuits, 1 m of the rod displacement resulted in 1.14 mv of dc voltage changes in the output.

published_or_final_version / Architecture / Master / Master of Philosophy