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FATIGUE PERFORMANCE OF A HYBRID CFRP/STEEL SPLICE DETAIL FOR MODULAR BRIDGE EXPANSION JOINTSArcovio, STEFANO 24 July 2013 (has links)
As traffic demand on bridges increases, loading cycles on critical components will increase, reducing their service life. Modular bridge expansion joints, which are imperative to allowing the bridge superstructure to move, are susceptible to fatigue damage at their field splice. These splices are used to connect segments of the total joint, during staged construction. Current splice designs are either bolted or welded connections, which allow stress concentrations to induce pre-mature fatigue failure. This thesis examines the use of a hybrid FRP/steel design under fatigue loading for use as a splice detail.
The splice detail consists of steel plates bolted to steel beam webs and CFRP pultruded plates adhesively bonded to the underside of the steel beam flanges. Two different moduli of CFRP were examined: Normal Modulus and Ultra High Modulus. Two beams of each modulus were tested under static conditions and six under constant amplitude fatigue loading. A testing rig was used to simulate similar bending moments experienced in bridge joints.
In the static tests, slippage of the web plates caused considerable stiffness loss and the slippage load varied drastically between CFRP moduli. For the fatigue tests, the intention was to reach two million cycles at the different constant load ranges. Stiffness degradation was noticed during the fatigue process, and was likely due to bolt pre-tension loss and/or plastic deformation of the adhesive. Specimens that reached two million cycles were monotonically loaded to failure. Once the CFRP had failed, a secondary mechanism was observed for reserve load capacity.
Simple beam mechanics were used to create prediction models for the initial spliced beam stiffness and peak CFRP load. Flexural and shear deformations of the spliced system were considered for beam stiffness. For the CFRP failure load prediction, a design peak strain in the CFRP was used to account for shear lag effects in the material and variability of the splice detail. While the model was inaccurate for beam stiffness, it provided a good approximate of the peak CFRP load. Based on the presented test data, the Normal Modulus CFRP hybrid splice detail showed better fatigue performance than conventional steel connection details. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-07-24 11:28:19.728
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Characterization of Moraxella bovis Aspartate TranscarbamoylaseHooshdaran, Sahar 12 1900 (has links)
Aspartate transcarbamoylase (ATCase) catalyzes the first committed step in the pyrimidine biosynthetic pathway. Bacterial ATCases have been divided into three classes, class A, B, and C, based on their molecular weight, holoenzyme architecture, and enzyme kinetics. Moraxella bovis is a fastidious organism, the etiologic agent of infectious bovine keratoconjunctivitis (IBK). The M. bovis ATCase was purified and characterized for the first time. It is a class A enzyme with a molecular mass of 480 to 520 kDa. It has a pH optimum of 9.5 and is stable at high temperatures. The ATCase holoenzyme is inhibited by CTP > ATP > UTP. The Km for aspartate is 1.8 mM and the Vmax 1.04 µmol per min, where the Km for carbamoylphosphate is 1.05 mM and the Vmax 1.74 µmol per min.
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To determine the immediate effect of sacroiliac and lumbar manipulation on quadriceps femoris and hamstring torque ratios in the contralateral limb in patients suffering from mechanical low back painLewis, Barbara Jane January 2005 (has links)
A dissertation submitted in partial compliance with the requirements for a Master's Degree in Technology: Chiropractic, Durban Institute of Technology, 2005. / Low back pain has been shown to be associated with inhibition of the lower limb musculature. This inhibition is called arthrogenic muscle inhibition (AMI). Sacroiliac joint dysfunction has been linked with AMI of the ipsilateral and contralateral quadriceps and hamstring muscles. Sacroiliac manipulation has been shown to significantly reduce ipsilateral AMI, however no studies have been conducted to illustrate the effect of sacroiliac manipulation on contralateral AMI. Neither have their been studies to show the presence or extent of spinal dysfunction between the levels of L2-L5 and its significance on muscle inhibition in the quadriceps and hamstring muscles, nor the effect of manipulation of these levels on AMI of the quadriceps and hamstring muscles.
The purpose of this study was therefore to determine whether spinal manipulation has an effect on AMI of the contralateral limb as well as that of the ipsilateral limb. / M
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Kurvenabgleich zur Bestimmung eines Systemverhaltens und von MaterialparameternKallmeyer, Rene 07 June 2017 (has links) (PDF)
Das Systemverhalten eines Einsteckvorganges und anschließenden Haltevorganges soll bestimmt werden. Bei den zu untersuchenden Komponenten sollen die Einpresskraft und die Haltekraft einem gewünschten Systemverhalten entsprechen. Zur Einstellung des gewünschten Systemverhaltens werden die Geometrieparameter variiert.
Zuvor wird das Werkstoffverhalten der Komponenten kalibriert. Die vorliegende Spannungs-Dehnungs-Kurve aus einem Zugversuch wird benötigt zur Beschreibung eines Werkstoffverhaltens.
Bei dieser Fragestellung geht es um die Parameteridentifikation für ein nichtlineares Materialmodell aus Ansys Workbench. Die Ergebnisse der Zugversuche werden als Referenzsignale in das Signal Processing eingelesen. Die in diesem Materialmodell vorhandenen Materialparameter sind so anzupassen, dass die numerischen Ergebnisse möglichst gut mit den experimentell gewonnenen Daten aus den Versuchen übereinstimmen.
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Data-driven approaches to load modeling andmonitoring in smart energy systemsTang, Guoming 23 January 2017 (has links)
In smart energy systems, load curve refers to the time series reported by smart meters, which indicate the energy consumption of customers over a certain period of time. The widespread use of load curve (data) in demand side management and demand response programs makes it one of the most important resources. To capture the load behavior or energy consumption patterns, load curve modeling is widely applied to help the utilities and residents make better plans and decisions. In this dissertation, with the help of load curve modeling, we focus on data-driven solutions to three load monitoring problems in different scenarios of smart energy systems, including residential power systems and datacenter power systems and covering the research fields of i) data cleansing, ii) energy disaggregation, and iii) fine-grained power monitoring.
First, to improve the data quality for load curve modeling on the supply side, we challenge the regression-based approaches as an efficient way to load curve data cleansing and propose a new approach to analyzing and organizing load curve data. Our approach adopts a new view, termed portrait, on the load curve data by analyzing the inherent periodic patterns and re-organizing the data for ease of analysis. Furthermore, we introduce strategies to build virtual portrait datasets and demonstrate how this technique can be used for outlier detection in load curve. To identify the corrupted load curve data, we propose an appliance-driven approach that particularly takes advantage of information available on the demand side. It identifies corrupted data from the smart meter readings by solving a carefully-designed optimization problem. To solve the problem efficiently, we further develop a sequential local optimization algorithm that tackles the original NP-hard problem by solving an approximate problem in polynomial time.
Second, to separate the aggregated energy consumption of a residential house into that of individual appliances, we propose a practical and universal energy disaggregation solution, only referring to the readily available information of appliances. Based on the sparsity of appliances' switching events, we first build a sparse switching event recovering (SSER) model. Then, by making use of the active epochs of switching events, we develop an efficient parallel local optimization algorithm to solve our model and obtain individual appliances' energy consumption. To explore the benefit of introducing low-cost energy meters for energy disaggregation, we propose a semi-intrusive appliance load monitoring (SIALM) approach for large-scale appliances situation. Instead of using only one meter, multiple meters are distributed in the power network to collect the aggregated load data from sub-groups of appliances. The proposed SSER model and parallel optimization algorithm are used for energy disaggregation within each sub-group of appliances. We further provide the sufficient conditions for unambiguous state recovery of multiple appliances, under which a minimum number of meters is obtained via a greedy clique-covering algorithm.
Third, to achieve fine-grained power monitoring at server level in legacy datacenters, we present a zero-cost, purely software-based solution. With our solution, no power monitoring hardware is needed any more, leading to much reduced operating cost and hardware complexity. In detail, we establish power mapping functions (PMFs) between the states of servers and their power consumption, and infer the power consumption of each server with the aggregated power of the entire datacenter. We implement and evaluate our solution over a real-world datacenter with 326 servers. The results show that our solution can provide high precision power estimation at both the rack level and the server level. In specific, with PMFs including only two nonlinear terms, our power estimation i) at the rack level has mean relative error of 2.18%, and ii) at the server level has mean relative errors of 9.61% and 7.53% corresponding to the idle and peak power, respectively. / Graduate / 0984 / 0791 / 0800 / tangguo1999@gmail.com
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In the hall of the flop king : two applications of perverse coherent sheaves to Donaldson-Thomas invariantsCalabrese, John January 2012 (has links)
This thesis contains two main results. The first is a comparison formula for the Donaldson-Thomas invariants of two (complex, smooth and projective) Calabi-Yau threefolds related by a flop; the second is a proof of the projective case of the Crepant Resolution Conjecture for Donaldson-Thomas invariants, as stated by Bryan, Cadman and Young. Both results rely on Bridgeland’s category of perverse coherent sheaves, which is the heart of a t-structure in the derived category of the given Calabi-Yau variety. The first formula is a consequence of various identities in an appropriate motivic Hall algebra followed by an implementation of the integration morphism (using the technology of Joyce and Song). Our proof of the crepant resolution conjecture is a quick and elegant application of the first formula in the context of the derived McKay correspondence of Bridgeland, King and Reid. The first chapter is introductory and is followed by two chapters of background material. The last two chapters are devoted to the proofs of the main results.
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Nanoscale measurements of the mechanical properties of lipid bilayersKöcher, Paul Tilman January 2014 (has links)
Lipid bilayers form the basis of the membranes that serve as a barrier between a cell and its physiological environment. Their physical properties make them ideally suited for this role: they are extremely soft with respect to bending but essentially incompressible under lateral tension, and they are quite permeable to water but essentially impermeable to ions which allows the rapid establishment of the osmotic gradients. The function of membrane proteins, which are vital for tasks ranging from signal transduction to energy conversion, depends on their interactions with the lipid environment. Because of the complexity of natural membranes, model systems consisting of simpler lipid mixtures have become indispensable tools in the study of membrane biophysics. The objective of the work reported here is to develop a deeper understanding of the underlying physics of lipid bilayers through nanoscale measurements of the mechanical properties of mixed lipid systems including cholesterol, a key ingredient of cell membranes. Atomic force microscopy (AFM) has been used extensively to measure the topographical and elastic properties of supported lipid bilayers displaying complex phase behaviour and containing mixtures of important PC, PE lipids and cholesterol. Phase transformations have been investigated varying the membrane temperature, and the effects of cholesterol in controlling membrane fluidity, phase, and energetics have been studied. Elastic modulus measurements were correlated with phase behaviour observations. To aid in the nanoscale probing of lipid bilayers, AFM probes with a high aspect ratio and tip radii of $sim$4~nm were fabricated and characterised. These probes were used to investigate the phase boundary in binary and ternary lipid systems, leading to the discovery of a raised region at the boundary which has implications for the localisation of reconstituted proteins as well as the role of natural domains or lipid rafts. The electrical properties of the probes were examined to assess their potential application for combined structural and electrical measurements in liquid. A novel technique was developed to aid in the study of the physical properties of lipid bilayers. Membrane budding was induced above microfabricated substrates through osmotic pressure. Modification of the adhesion energy of the bilayer through biotin-avidin linking was successful in modulating budding behaviour of liquid disordered bilayers. The free energy of the system was modelled to allow quantitative information to be extracted from the data.
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A Combinatorial Exploration of Elliptic CurvesLam, Matthew 01 January 2015 (has links)
At the intersection of algebraic geometry, number theory, and combinatorics, an interesting problem is counting points on an algebraic curve over a finite field. When specialized to the case of elliptic curves, this question leads to a surprising connection with a particular family of graphs. In this document, we present some of the underlying theory and then summarize recent results concerning the aforementioned relationship between elliptic curves and graphs. A few results are additionally further elucidated by theory that was omitted in their original presentation.
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Development of a Software Code for Pharmacokinetic Analysis of PET Data.Shamas, Sofia 01 January 2006 (has links)
To improve efficacy in the field of drug discovery simpler in vivo, non invasive methods such as PET and SPECT are used. Pharmacokinetic analysis is the underlying method for analyzing the PET data. Imaging of tracer distribution is used to study a metabolic process. Using Matlab as the programming language, a software tool is developed to analyze the quantitative information from PET and to obtain an estimate of pharmacokinetic parameters, representing the bio- distribution of the radiotracer. A Graphical User Interface developed allows two types of analysis, depending upon the nature of the radiotracer: Compartmental Modeling and Logan Plot Analysis. Compartmental analysis gives us rate constants and blood volume where as Logan analysis gives us the distribution volume as the parameter of interest. Code validation is done for two radiotracers, 15O-water (Single compartment model) and FPAC (Logan Plot). Results from the code were compared with those obtained during a research work done to study MDR.
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CHEMOMETRIC ANALYSIS OF COMPREHENSIVE TWO-DIMENSIONAL LIQUID CHROMATOGRAPHIC-DIODE ARRAY DETECTION DATA: PEAK RESOLUTION, QUANTIFICATION AND RAPID SCREENINGBailey, Hope P. 09 October 2012 (has links)
This research project sought to explore, compare and develop chemometric methods with the goal of resolving chromatographically overlapped peaks though the use of spectral information gained from the four-way data sets associated with comprehensive two-dimensional liquid chromatography with diode array detection (LC ´ LC-DAD). A chemometric method combining iterative key set factor analysis (IKSFA) and multivariate curve resolution-alternating least squares (MCR-ALS) was developed. In the section of urine data analyzed, over 50 peaks were found, with 18 visually observable and 32 additional compounds found only after application of the chemometric method. Upon successful chemometric resolution of chromatographically overlapped peaks, accurate and precise quantification was then necessary. Of the compared methods for quantification, the manual baseline method was determined to offer the best precisions. Of the 50 found peaks from the urine analysis, 34 were successfully quantified using the manual baseline method with percent relative standard deviations ranging from 0.09 to 16. The accuracy of quantification was then investigated by the analysis of wastewater treatment plant effluent (WWTPE) samples. The chemometrically determined concentration of the unknown phenytoin sample was found to not exhibit a significant difference from the result obtained by the LC-MS/MS reference method, and the precision of the IKSFA-ALS method was better than that of the precision of the LC-MS/MS analysis. Chromatographic factors (data complexity, large dynamic range, retention time shifting, chromatographic and spectral peak overlap and background removal, were all found to affect the quantification results. The last part of this work focused on rapid screening methods that were capable of locating peaks between samples that exhibited significant differences in concentration. The aim here was to reduce the amount of data required to be resolved and quantified to only those peaks that were of interest. This would then reduce the time required to analyze large, complex samples by eliminating the need to first quantify all peaks in a given sample for many different samples. Both the similarity index (SI) method and the Fisher ratio (FR) method were found to fulfill this requirement in a rapid means of screening fifteen wine samples.
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