Browsing by Subject "Structural"
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Item Cenozoic stratigraphy and geomorphology of Lynn and Terry counties, Texas.(Texas Tech University, 1975-08) Goolsby, Jimmy EarlNot availableItem Crustal Structure of the Central High Plains of Texas from Rayleigh Wave Dispersion(Texas Tech University, 1972-12) Stanton, James CliffordNot Available.Item Crustal structure of the Texas gulf coast(Texas Tech University, 1973-05) Keller, George R.The coastal region of Texas is a zone of transition from oceanic structure in the Gulf of Mexico to continental structure in central Texas. Knowledge of crustal structure in this region is necessary to understand the tectonic history of the coastal region of Texas, the Ouachita system, and the Gulf of Mexico. Gravity measurements were made and combined with measurements from earlier studies to produce a gravity map of the coastal region of Texas. These data were interpreted by computer modeling, and analysis of the data suggests that the. crust thins and the sedimentary column thickens from central Texas toward the coast. The buried core of the Ouachita system has a distinct positive gravity signature, and gravity profiles suggest that the same general crustal structure exists through much of the Texas coastal region. Two tripartite arrays of vertical long-period seismographs were deployed for study of Rayleigh wave propagation in the coastal region of Texas. Analysis of Rayleigh wave group-velocity dispersion in the Rio Grande Embayment area suggests that thick Paleozoic, as well as thick Mesozoic and Cenozoic, sediments are present. 7JDsence of a typical granitic layer is also suggested. The model proposed for this area is a crust 32 km thick composed of 12 km of basaltic material and 20 km of sedimentary rocks. The second tripartite was deployed in the area of the central Texas Gulf Coast. The model proposed for this area is a crust 31.5 km thick composed of 13.5 km of basaltic material, 5 km of Mesozoic and Cenozoic sediments, and 9. km of Paleozoic rocks which are in part of igneous origin. The combination of geological data, gravity data, previous seismic refraction studies, and Rayleigh wave dispersion data suggests a generalized crustal model which is valid all along the Texas Gulf Coast. The generalized model is b€:F:t explained by interpreting the Ouachita system. as a Paleozoic-Cordilleran type mountain belt and the Texas Gulf Coast as the site of the Paleozoic subduction zone.Item Crustal xenoliths from Potrillo Maar: implications for evolution of continental crust beneath the southern Rio Grande rift(Texas Tech University, 2003-08) Chattopadhyay, IndraniThe mid-crustal xenoliths from Potrillo maar record a petrologic and geochemical history that has until now been unknown from the Potrillo volcanic field. The igneous and meta-igneous xenoliths are samples of one or more plutonic bodies that crystallized at depths from 7-14 km (middle to upper crust). The rock unit ranges in composition from hornblende biotite diorite to quartz monzonite and monzogranite; it is broadly alkalicalcic The initial Sr87Sr86 suggests that the source region is heterogeneous or that the parental magmas were contaminated by crustal material. At least three geochemical groups can be identified, primarily on the basis of silica content. There is considerable overlap between groups 1 and 2, and the boundary between these two groups cannot be distinguished graphically. The third group is granitic and is geochemically distinct from groups 1 and 2. A dioritic composition is thought to represent mafic parental magma. Its calculated liquidus temperature at 2% H2O and 4 Mpa pressure is 1172°C. The presence of fossiliferous limestone xenoliths indicates that the Potrillo maar eruption sampled rocks of late Paleozoic age. However, the age of marble and quartzite xenoliths are not known. The quartzite xenoliths are relatively undeformed, but isoclinal folding in some of the marble xenoliths suggests subsurface deformation that has not been observed in local surface exposures of metasedimentary rocks. One model proposed for the crust under the southern Rio Grande rift assumes that the marble is late Paleozoic in age. The fossiliferous limestones are late Paleozoic in age and are older than the plutonic rocks. The relative age of the deformed marbles in this model is not clear, it can be deformed with the plutonic rocks or due to an earlier regional extensional event. In the second model, marble is proposed to result from contact metamorphism in the aureole of a plutonic rock body at a depth of 7-14 km. The presence of marble and calc-silicate xenoliths in dioritic blocks is consistent with a correlation of the marble with surface exposures of the Castner Marble in the Franklin MountainsItem Depositional dynamics of the Brushy Canyon Formation, Delaware Basin, Texas(Texas Tech University, 1966-05) Germain, Louis Charles St.The Brushy Canyon Formation, lowermost of the DeLaware Mountain Group, represents a network of submarine channel and overbank deposits, The site of deposition, the Delaware basin, was analogous to present deep basins off the coast of southern California, such as San Pedro, Sc.nta Monica, and San Diego basins. Because recent data from present oceans indicate that submarine channels like those in the Delaware basin initiate at the mouths of submarine canyons, the existence of numerous submarine canyons along the margin of the ancient Delaware basin is inferred. By analogy with the above recent examples, sediment was probably delivered by tidal and longshore current action into the heads of submarine canyons which extended back onto the platform. Subaqueous bottom flows initiated by earthquakes, storm generated waves, or by overloading, transported sediment down the canyons and into the deep basin via the subsea channels. The coarser material remained in the channels which extended many miles beyond the canyon mouths, whereas much of the finer material spilled over the channel margins and produced natural Levees and finely laminated overbank deposits. These overbank deposits are much Like the flood plain deposits made by subaerial streams. Current flow data obtained from the Brushy Canyon Formation are remarkably unidirectional, which seems to be a characteristic of sediment deposited by this mechanism. The prevailing current direction is southeast (i, e,, basinward), perpendicular to the northeast-southwest trending platform margin.Item Descriptive geometry in the geosciences(Texas Tech University, 1952-06) Huzarski, Richard GeorgeNot availableItem Effects of prestress on strains and deflections in pretensioned beams(2013-12) Koutrouvelis, Stergios; Tassoulas, John LambrosIn this research, nonlinear structural analysis along with finite element analysis were carried out for a pretensioned concrete beam at different levels of pretension in order to examine the effect of the change in the tendon force on the geometric stiffness of the beam. Several results were obtained for deflection, horizontal displacement and surface strains to investigate how they are affected by the level of pretension under the application of the same load in each case. These computations were compared with the tendon force to conclude whether they can be used to estimate the pretension level by means of simple measurements. The purpose was to develop a methodology for quantifying the prestress losses by taking advantage of the dependence of the prestressed concrete beam stiffness on the tendon force.Item Feasibility studies of two-way composite steel-deck slab(Texas Tech University, 1987-12) Wong, Chee KheongNot availableItem Identifying structural mismatch for optimization models(Texas Tech University, 2005-08) Saenz, Jesse; Riggs, James B.; Hoo, Karlene A.Major successes have been achieved with the application of on-line optimization applications particularly real-time optimization (RTO). Although there has been much success with RTO, it has been shown that the performance of an RTO application tends to decrease over time due to changes in the process that are unaccounted for in the optimization models. The main objective of this work is to develop a procedure that can be used in an industrial environment to identify structural model mismatch between the actual process units and the optimization models. RTO uses complex process models to determine the optimum operating conditions of a process and these models are updated using process measurements so that they provide the most accurate predictions. It is shown in this study that structural model mismatch can be identified by looking at the variation in the calculated model parameters when there are variations in the process operating conditions and sensor noise is not excessive. The effect of model mismatch on calculated model parameters is studied for a heat exchanger, CSTR, distillation column, and an ethylene furnace in this work. Because RTO applications use process measurements to update model parameters a better measurement should lead to an improvement in the performance of the application. It is shown in this study that decreasing the amount of noise associated with a sensor used by an optimization application leads to a small increase in overall profit, less than 0.4% for the cases considered here, and the increase in profit depends on the shape of the optimization curve about the optimum.Item Sediments and Topography of the Western Gulf of Mexico(Texas Tech University, 1967-08) Suggs, James De ShaeRelative frequencies of temperature sensitive planktonic foraminifera, in sediment cores raised from the continental slope and Sigsbee Abyssal Plain in the Gulf of Mexico, indicate alternating periods of warm and cold climate during the Pleistocene. Wisconsin glacial sediments in the Sigsbee Abyssal Plain are characterized by numerous bottom flow intervals separated by thin pelagic intervals. Texas and Mexico coastal areas may be ruled out as a major source of sediment in the deep Gulf of Mexico. The Mississippi River Submarine Canyon and its submarine distributary channels were alternately activated during interglacial and interstadial periods when sea level was higher. The Pleistocene Mississippi River served as the major source of sediment and the Mississippi River Submarine Canyon and Mississippi Cone served as the major transport route for sediments of the Sigsbee Abyssal Plain.Item Structural characterization of post-PKS enzymes involved in spinosyn biosynthesis(2014-05) Isiorho, Eta Amauche; Keatinge-Clay, Adrian Tristan; Liu, Hung-wen, 1952-Saccharopolyspora spinosa is a rare actinomycete that synthesizes the secondary metabolite spinosyn A, which is an active ingredient in several important commercial insecticides. Spinosyn aglycone formation occurs via a type I polyketide synthase. After release of the polyketide chain from the synthase, various tailoring enzymes modify the aglycone core. These unique enzyme transformations result in unusual structural characteristics found in spinosyn A. The enzymes SpnG, SpnP, SpnF and SpnL each perform a key reaction during post-PKS processing. The work presented in this dissertation focuses on the structural determination and analysis of SpnG, SpnP, SpnF and SpnL. SpnG, which naturally catalyzes the 9-OH rhamnosylation of spinosyn, is capable of adding diverse sugars to the spinosyn aglycone from TDP-hexoses, such as TDP-glucose. However, the substitution of UDP-glucose for TDP-glucose as the donor substrate is known to result in a >60,000-fold reduction in k [subscript cat]. The structure of SpnG at 1.65 Å resolution, the 1.86 Å resolution structure of SpnG bound to TDP, and the 1.70 Å resolution structure of SpnG bound to AGL were determined. The SpnG-TDP complex reveals how SpnG employs N202 to discriminate between TDP- and UDP-sugars. The SpnG-AGL complex shows that SpnG binds the acceptor substrate primarily through hydrophobic interactions and implicates H13 as the potential catalytic base. A model for how rhamnose binds in the active site was constructed to elucidate which features enable SpnG to transfer diverse hexoses. SpnP transfers forosamine from a TDP-D-forosamine donor substrate to a spinosyn pseudoaglycone acceptor substrate. The structures of SpnP and its complex with TDP were determined to 2.50 Å and 3.15 Å resolution, respectively. SpnP possesses a structural feature that has only been previously observed in a related glycosyltransferase, which employs an auxiliary protein that aids in its catalysis. This unique feature may be a used as a predictive motif of glycosyltransferases that interact with an auxiliary protein. SpnF and SpnL are two novel S-adenosyl-L-methionine dependent cyclases. Structural data was utilized in order to gain insight into the unusual cycloaddition catalyzed by the putative Diels-Alderase and Rauhut-Currierase, SpnF and SpnL, respectively. Together these structures provide valuable insights into the unusual mechanisms involved in spinosyn biosynthesis.Item Structural Relationships and Chronologies of Two Chert to Clastic Rock Successions, Western Sierra Nevada, California(Texas Tech University, 1976-08) Wethington, Lynette DianeIn the western Sierra Nevada, California, an east to west rock succession of layered chert, pelitic-siliceous rock, and fine-grained clastic rock characterizes part of the Paleozoic Calaveras Formation. Along the Merced River, west of Yosemite, and at Little Bald Mountain, west of Lake Tahoe, mesoscopic structures in these lowgrade metamorphic rocks are chiefly folds and fracture cleavage in the cherts, folds and poorly defined cleavage in the pelitic-siliceous rocks, and slaty or crenulation cleavage in the fine-grained clastic rocks; lineations mainly crenulations) occur in all lithologies. In the Merced River area, layering ( S Q ) mainly strikes northerly and dips steeply east; a metamorphic alignment of micas (S,) parallels S^; cleavages (S2) strike west-northwest and dip steeply south; and folds (F^) and lineations ( K ) are parallel, mainly plunge steeply to the southeast, and are dispersed in S^- S^ parallels F^ axial planes. The subvertical disposition f S^ may be a product of tilting or isoclinal folding (D,). Later, F^ folds, S^, S^, and 1^ developed during D^ under conditions of greenschist facies metamorphism. In the Little Bald Mountain area, layering ( S Q) strikes mainly northeast and dips steeply south; a metamorphic alignment of micas (S^) parallels S^; F^ folds plunge shallowly with diverse trends; cleavages (Sp) strike north-northwest and dip subvertically; F^ folds plunge steeply to the south; and lineations ( K ) plunge steeply and are dispersed in S Q . S2 transects F^ folds and may be axial plane cleavage of Fp folds. 1, is arallel to ?2 ^^^^ ^^^ ^2 " ^0 "intersections. F, folds nd S^ developed in association with tilting of isoclinals folding (D,) which was accompanied by low-grade metamorphism. Later, Sp, F^ folds, and 1, formed under conditions of greenschist facies metamorphism during Dp. The two areas are similar with respect to absence of significant penecontemporaneous deformation, rock succession, mesoscopic structures, and proposed deformational chronologies. The first (D^ and D.) and second (D- and Dp) deformational events of the two areas tentatively are correlated with the Sonoma and Nevadan orogenies, respectively.Item The Structural and Metamorphic History of the Oakhurst Roof Pendant, Mariposa and Madera Counties, California(Texas Tech University, 1972-12) Russell, Lee RThe Oakhurst roof pendant, near Oakhurst, California, consists of three pre-Cretaceous clastic metasedimentary rock units, surrounded and intruded by rocks of the Sierra Nevada batholith. Two zones of probable "sheared granitic" and "ultramafic" rocks trend northwesterly and are approximately aligned with the Foothills fault system farther north. The dominant mesoscopic feature of the pendant is a northwesterly striking foliation which forms a downward converging fan. Earlier-formed hornblende lineations have been transposed into this foliation plane, as shown by Schmidt-net projections. Rocks comprising the three units show three textural stages: (1) Early amphiboles and diopside overgrown by later static amphibole pophyroblasts. Hornblende lineations in one of these units show a great-circle Schmidt-net distribution. (2) A superimposed, well-developed, cataclastic ^-plane (the mesoscopic foliation). (3) Late, static growth of poikiloblastic micas and diopside, straight well-crystallized micas, near polygonal quartz and feldspar, epidote and biotite after amphibole and diopside, and chlorite after biotite. The "sheared granitic" and "ultramafic" rock bodies display the same prominant foliation and static and retrograde metamorphic textures as do rocks of the three major units. These data are interpreted as reflecting three dominant post-sedimentary structural (D) and thermal (M) events: (1) M^/D- consists of episodes of synkinematic metamorphism, which resulted in an early foliation, _S, , and of static metamorphism, M . M is of the epidoteamphibolite facies. (2) D resulted in the cataclastic development of the prominent fanning foliation, S_^; the fan is indicative of an antiformal structure. This antiform and foliation developed as a consequence of subvertical movement, as indicated by the geometry of transposition of hornblende lineations into S^^. The "sheared granitic" and "ultramafic" rock bodies were emplaced along two shear zones during D. These zones could be the roots of thrust sheets and possibly an extension of the Foothills fault system, which has been mapped as terminating 20 miles to the northwest. (3) M was a static metamorphic event associated with batholithic intrusion. Locally, this event was characterized initially by high temperatures, but retrograde conditions generally prevailed. M^ was dominantly of the albiteepidote- hornfels facies, but locally of the hornblendehornfels facies. Radiogenic dates of batholithic rocks near the pendant date M as Late Jurassic-Middle Cretaceous Therefore, M /D and D are pre-Late Jurassic. M /D may be a southerly expression of the Late Permian-Early Triassic Sonoma Orogeny. D apparently reflects the deformation associated with the classical Nevadan Orogeny, and M corresponds to late or postorogenic granitic intrusion of the Sierra Nevada batholith.Item UT Fire, a preprocessor for SAFIR2007, for analysis of heat transfer for structural members exposed to fire(2009-12) Jennings, Timothy Mark; Engelhardt, Michael D.; Helwig, Todd A.This thesis describes the development of the computer program UT Fire, which serves as a preprocessor for the computer program SAFIR2007. SAFIR2007, developed at the University of Liege in Belgium, conducts heat transfer analysis and structural response analysis for structures subjected to fire. The preprocessor UT Fire was developed to allow a simplified graphical interface for input to the heat transfer portion of SAFIR 2007. This thesis provides step by step instructions on the use of UT Fire and illustrates its use through a series of detailed examples.