Monolithic ceramic materials have been used in industry for hundreds of years. These materials have proven their usefulness in many applications, yet, their potential for critical structural applications is limited. The existence of an imperfection in a monolithic ceramic on the order of several microns in size may be critical, resulting in catastrophic failure. To overcome this extreme sensitivity to sman material imperfections, reinforced ceramic materials have been developed. A ceramic matrix which has been reinforced with continuous fibers is not only less sensitive to microscopic flaws, but is also able to sustain significant damage without suffering catastrophic failure. A borosilicate glass reinforced with several layers of plain weave silicon carbide cloth (Nicalon) has been studied. The mechanical testing which was performed included both flexural and tensile loading configurations. This testing was done not only to determine the material properties, but also to initiate a controlled amount of damage within each specimen. Several nondestructive testing techniques, including acousto-ultrasonics (AU), were performed on the specimens periodically during testing. The AU signals were monitored through the use of an IBM compatible personal computer with a high speed data acquisition board. Software has been written which manipulates the AU signals in both the time and frequency domains, resulting in quantitative measures of the mechanical response of the material. This paper will compare the measured AU parameters to both the mechanical test results and data from other nondestructive methods including ultrasonic C-scans and penetrant enhanced X-ray radiography. / Master of Science

Amino polyaromatic hydrocarbons (amino PAHs) and nitro polyaromatic hydrocarbons (nitro PAHs), two highly mutagenic classes of compounds, are proposed to be metabolized to an electrophilic aryl nitrenium ion which attacks DNA and forms DNA adducts. A structure-activity relationship was investigated between aryl nitrenium ion stability and mutagenic activity. Arylnitrenium stability for seventeen amino PAHs was measured using electron ionization mass spectrometry. The ratio of [M-1]⁺/M⁺ intensities was used as an indicator of nitrenium ion stability. These values were then compared to mutagenicity data from the Ames Salmonella assay. Physical descriptors of isomer classification (based on ring size and shape) and isomer position of substitution were used in the statistical analysis. A strong correlation between mutagenicity, isomer classification, and stability was found (r²= 0.899 and p<0.001). This finding agrees with reported literature that the compound's physical features of ring size and position of substitution affect mutagenicity. A high correlation of r² = 0.955 was found between mutagenicity, isomer classification, and stability for three sets of isomers: 1- and 2-aminoanthracene, 1- and 2-aminonaphthalene, and 1- and 2-aminofluorene. The nitrenium ion formed from the 2 position was found to be less stable and more mutagenic than the 1 position. This finding agrees with correlations found between mutagenicity and LUMO (Lowest Unoccupied Molecular Orbital) calculations of the electrophilicity of the nitrenium ion. These results indicate that the less stable the nitrenium ion within an isomer pair, the more mutagenic the amino PAH. / Master of Science

The active magnetic bearing (AMB) is a relatively new technology which has many advantages compared with conventional bearing design. In an AMB system, the rolling-element back-up bearings are indispensable to protect the magnetic bearing rotor and stator, and other stationary seals along the rotor shaft. In this paper, a theoretical formulation is proposed and solved numerically to examine the transient response of the flexible rotor, from the time just previous to the AMB shuts down and including the rotor drop onto the back-up bearing. The backward whirl of the rotor, which may lead to the destructive damage of the machinery, has been analytically predicted at very light support damping and very high support damping. Also, the vibration due to the non-linearity of the contact point geometry has been included in the analysis. The influence of the support damping on the displacement of the disk and also the contact force between the journal and the inner-race of the back-up bearing have been computed for various rotor system parameters. By comparing these results with the optimum support damping for the simple flexible rotor model, it is shown that this support damping optimization can be applicable for specifying the required optimum range of support damping for the back-up bearings of AMB systems. / Master of Science

The need for better performance of turbomachinery with active magnetic bearings has necessitated a study of such systems for accurate prediction of their vibrational characteristics. This research presents a modification of existing transfer matrix methods for rotor analysis, to predict the response of rotor systems with active magnetic bearings. The position of the magnetic bearing sensors is taken into account and the effect of changing sensor position on the vibrational characteristics of rotor systems is studied. The modified algorithm is validated using a simpler modified Jeffcott model. The effect of changing from a rotating unbalance excitation to a constant excitation in a single plane is also studied. An eight-stage centrifugal compressor rotor is analyzed using the modified transfer matrix code. The results for a two-mass Jeffcott model are presented as plots of critical frequency vs. sensor position and amplitude at critical frequency vs. sensor position. Plots of amplitude vs. frequency and phase angle vs. frequency for different cases of sensor location are also presented. The results obtained by analyzing this two-mass model with the modified transfer matrix method have been compared with the results of the modified Jeffcott analysis for the purpose of verification. Also included are plots of amplitude vs. frequency and phase angle vs. frequency for the eight-stage centrifugal compressor rotor. These plots will demonstrate the significant influence that sensor location has on the critical frequencies and the amplitudes at the critical frequencies of the rotor system. / Master of Science

Rudbeckia hirta I Marmalade' plants at different leaf numbers were exposed to a (long day) LD photo period in order to quantify the end of juvenility. A quadratic relationship existed between flowering and both the number of leaves the plant possessed and the number of days from onset of LD. The loss of juvenility occurred in the shortest time, 42 days, plants had 15-24 true expanded leaves. The greatest stem height also corresponded to this same leaf number. The number of LD received did not affect ray floret number per inflorescence, scape length and capitulum diameter excluding ray florets. Gaillardia pulchella flowered most rapidly in 49 days, with a minimum of 14-20 expanded leaves as described in a quadratic relationship. Histological studies during evocation indicated an increase in apical meristem widths (120 pm to 224 pm) and heights (21 ~m to 48 pm), an increase of 2 to 5 tunica cell layers, greater corpus organization, and a lower point of primordia attachment with respect to increased doming of the apex all occurring with maturity of the apex. Solidago flexicaulis exhibited a complex (combination) photoperiodic response, requiring an extended LO exposure prior to SO initiation. The last treatment, consisting of 12-week-old-plants transferred from LO to SO, flowered most rapidly in 62 days. Other measured characteristics such as stem length, dry weight of all tissue above and below the soil line, number of basal shoots and main axis leaf number were not different depending on amount of SO induction. There was a difference in the above measured variables, except emerged basal shoots and leaves per main axis, between control LO plants and all averaged SO treated plants. / Master of Science

Earlier studies have demonstrated that nitrosoureas such as 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) and chlorozotocin (CLZ) can cure almost 100% of C57BL/6 mice bearing syngeneic LSA tumor. In contrast, similiar or higher doses of streptozotocin (STZ) completely failed to cure LSA-bearing mice. Further studies revealed that the efficacy of nitrosoureas may depend on their immunomodulating properties. In the current study, therefore, attempts were made to investigate the effects of these nitrosoureas on the immune system of normal and LSA tumor-bearing mice. Treatment of normal C57BL/6 mice with 5 intraperitoneal injections of 20 mg/kg body weight of BCNU or CLZ caused an increase in the percentage of CD4⁻ CD8⁻ T cells and a decrease in the percentage of CD4⁺CD8⁺ T cells in the thymus. In addition, such treatment also caused an increase in the percentage of CD4⁺ T cells without significantly affecting the CD8⁺ T cells in the thymus. However, when total cellularity of the thymus was studied, BCNU and CLZ were found to decrease the total number of CD4⁺CD8⁺ T cells without significantly affecting the other subsets. In contrast, similiar or higher (100mg/kg body weight) doses of STZ had no significant effect on the total number and percentages of T ceil subsets in the thymus. Also, BCNU and CLZ but not STZ-treatment caused a 50% decrease in the total number of CD4⁺ and CD8⁺ T cells in the spleen. Interestingly in tumor-bearing mice, BCNU treatment was followed by a ten-fold increase in the percentage of CD4⁺ T cells found in the peritoneal cavity. The percentages of CD8⁺ cells increased also, but to a lesser degree. These changes were limited to the peritoneal cavity which is the site of tumor growth. When T cells in the spleens of nitrosourea-treated normal mice were functionally analyzed, it was observed that BCNU and CLZ caused a dramatic decrease in the T cell responsiveness to Con A, anti-CD3, and PMA + calcium ionophore stimulation. In contrast, STZ treatment failed to significantly inhibit the T cell responsiveness to these activation signals. Using the accessory cell-dependent and independent assays, BCNU and CLZ were found to suppress the functions of both T cells and macrophages in normal mice. BCNU and CLZ also suppressed the B cell responsiveness to lipopolysaccharide (LPS). Also, addition of growth factors such as IL-1, IL-2, IL-4 and IL-6 failed to reconstitute the defective responsiveness of BCNU and CLZ-treated T cells and macrophages. Together these data suggest that nitrosoureas have varying immunomodulating properties and this may in turn determine their efficacy in the treatment of cancer. / Master of Science

Discussed is the design, implementation and use of a graPHIGS (IBM PHIGS) based sub-system that provides for shading of graphical models using the Phong shading technique. The ISO standard for 3D graphics, PHIGS, provides for wireframe display and manipulation of graphics data. PHIGS + implementations, while providing this capability, will not be widely available for some time. This capability will provide a generally useful extension to PHIGS for use by PHIGS based applications. The software provides the applications programmer with a graPHIGS based instruction set which acts as a superset to the current graPHIGS calls. Using the provided functions the user can quickly do hidden surface elimination and Phong rendering of 3-D models in 3-D views. The program contains approximately 15,000 lines of C code and uses graPHIGS inquiries and calls for information retrieval and data structure maintenance. / Master of Science

Several factors related to the proper shipping of fresh seafood by airplane were studied in this thesis. These included precooling, gel pack effectiveness, external temperatures encountered by shipping containers, and coolant placement in a shipping container. Experiments were conducted to determine cooling times of 10 and 20 pound boxes and 10 pound bags of whole fish. The ”10-pound” box was then modelled using finite element techniques. The model was found to accurately predict the temperature response of the box for a constant temperature boundary condition. Different boundary conditions were applied to the model. These were: constant temperature (such as an ice-slurry); low, medium and high velocity air (such as in a commercial refrigerator). The model was then used to predict cooling times for the other boundary conditions. The enthalpy needed to thaw the contents of different gel packs was measured and compared to that of ice. None of the gel packs had as high an enthalpy as ice. In addition, the warming characteristics of the gel packs with the highest enthalpy was compared to those of ice. It was found that the warming characteristics of the gel pack appeared to be similar to that of ice. The actual shipment of seafood to distant markets was studied by sending a data logger with several shipments to the west coast and collecting temperature data every 5 minutes during these shipments. Temperatures in 12 different locations were measured. Of particular interest were the outside temperatures which were later used in the modeling of the shipments. The shipments were sent in EQ containers. The containers experienced a wide range of temperatures. A finite element model was developed to predict the temperature of seafood under simulated transport conditions. Two boundary conditions were applied to the model; these were still air at 30°C and the approximate temperatures encountered during one of the shipments. Three different arrangements of coolant placement were studied. These were all ice on top of the product, half the ice on top and half in a layer in the middle of the product, and half of the ice on top of the product and half of the ice below the product. The latter arrangement provided the most uniform temperature distribution of the three through 18 hours of simulation. It was also found that shipments should be delivered in less than 24 hours for the amount of coolant used. / Master of Science

Spectacular production rates have been achieved by certain U.S. longwalls, and yet a large number of longwall operations have failed to meet anticipated production targets. This study attempts to identify the primary factors which contribute to the production shortcomings of many marginal longwall operations. This study presents details of the classification and analysis of delay data for a group of thirty-nine longwall sections located in the eastern and mid-eastern United States. Downtime data correspondIng to over fourteen-thousand shifts were collected and classified according to equipment type, delay type, and specific delay event. A dBase IV-based database was constructed to allow flexible interrogation of the data. The relative downtime contributions of the various equipment components and of the delay types have been determined. Machine availabilities and system availabilities are presented. Probability density functions have been flit to the time-to-failure and to the time-to-repair data sets, both for the principal equipment types and for the longwall system as a whole. Recommendations are made for increasing the availability of longwall systems. / Master of Science

The dynamic characteristics of the K-Gill anemometer were evaluated by comparing the anemometer with a hot wire system in a field test, after the static characteristics of the anemometer had been evaluated in a wind tunnel test. The wind tunnel test showed a non-linear and a non-cosine behavior, as shown in previous studies (Ataktürk, 1988; Pond et al., 1979). The turbulence energy spectra from the field test revealed that the propeller anemometer behaves like a single-pole low-pass RC filter, as suggested in previous studies (Ataktürk, 1988; Pond et al., 1979; MacCready and Jex, 1964). The test results showed that mean wind velocity components can be measured with an error of 2%. To determine the Reynolds stress values, uw covariance and friction velocity from different methods were compared. When the stability conditions were unknown, the resulting Reynolds stress estimations have 15% relative differences between different methods. / Master of Science