Bracing members are considered to be effective earthquake-resistant elements as they improve the lateral strength and stiffness of the structural system and contribute to seismic energy dissipation by deforming inelastically during severe earthquake motions. However, the cyclic behavior of such bracing members is quite complex because it is influenced by both buckling and yielding. This thesis presents simple but an efficient analytical model that can be used to simulate the inelastic cyclic behavior of steel braces. This model achieves realism and efficiency by combining analytical formulations with some semi-empirical formulas developed on the basis of a study of experimental data. A brace is idealized as a pin-pin ended member with a plastic hinge located at mid-length of a brace Input parameters of the model are based on only material properties such as steel yield strength and modulus of elasticity as well as geometric properties including cross-sectional area, moment of inertia, etc. The obtained results are verified by the experimental and available analytical results.

Recent ground failure case histories after 1994 Northridge, 1999 Kocaeli and 1999 Chi-Chi earthquakes revealed that low-plasticity silt-clay mixtures generate significant cyclic pore pressures and can exhibit a strain-softening response, which may cause significant damage to overlying structural systems. These observations accelerated research studies on liquefaction susceptibility of fine-grained soils. Alternative approaches to Chinese Criteria were proposed by several researchers (Seed et al. 2003, Bray and Sancio 2006, Boulanger and Idriss 2006) most of which assess liquefaction triggering potential based on cyclic test results compared on the basis of index properties of soils (such as LL, PI, LI, wc/LL). Although these new methodologies are judged to be major improvements over Chinese Criteria, still there exist unclear issues regarding if and how reliably these methods can be used for the assessment of liquefaction triggering potential of fine grained soils. In this study, results of cyclic tests performed on undisturbed specimens (ML, CL, MH and CH) were used to study cyclic shear strain and excess pore water pressure generation response of fine-grained soils. Based on comparisons with the cyclic response of saturated clean sands, a shift in pore pressure ratio (ru) vs. shear strain response is observed, which is identified to be a function of PI, LL and (wc/LL). Within the confines of this study, i) probabilistically based boundary curves identifying liquefaction triggering potential in the ru vs. shear strain domain were proposed as a function of PI, LL and (wc/LL), ii) these boundaries were then mapped on to the normalized net tip resistance (qt,1,net) vs. friction ratio (FR) domain, consistent with the work of Cetin and Ozan (2009). The proposed framework enabled both Atterberg limits and CPT based assessment of liquefaction triggering potential of fine grained low plasticity soils, differentiating clearly both cyclic mobility and liquefaction responses.

This study aims to investigate the effects of event type (concepts represented by the graph) in graph comprehension with three graph types (line, bar, area) and two graph designs (linear, round) by means of two different task types (trend assessment, discrete comparison). A novel round graph type was designed for that purpose. Five hypotheses were investigated: H1: Graph type affects comparison strategies / H2: Event type affects comparison strategies / H3: Graph design affects comparison strategies / H4: Graph design and event type interact / H5: Task type affects comparison strategies. As a method to collect data on subjects&#039 / graph perception and comprehension, behavioral (recollected values, word preferences in the description task) and eye-tracking data (scan paths, gaze length, number of fixation, fixation duration and number of transitions) were collected. As an outcome of this thesis, while the event type and the task type seemed to affect the graph comprehension, the effect of graph type, the graph design and interaction between graph design and event type were partially observed. These results point out that although round and linear graph designs are informationally equivalent, the round graphs are computationally better suited than linear graphs for the interpretation of cyclic concepts. However, grasping trend information for the linear events and making discrete comparisons were achieved with the same effort in both graph designs. This result is not trivial at all, given the fact that participants were not familiar with the round graph design and were confronted with them in this experiment for the first time.

Fuel cells are the tools which convert chemical energy into electricity directly by the effective utilization of hydrogen and oxygen (or air). One of the most important barriers for the fuel cell commercialization is the durability of the fuel cell components in the long term operations. In this study, the durability of the PEM fuel cell electrocatalysts were investigated via cyclic voltammetry (CV) and rotating disk electrode (RDE) experiments in order to determine the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) which corresponds to the half cell reactions in the fuel cell. PEM fuel cell electrodes mainly composed of carbon supported Pt catalysts. In long term operations due to Pt dissolution and carbon corrosion some properties of the electrocatalysts can be changed. Performance losses in catalysts mainly depend on / i) decrease in the total metal surface area (SA) and the electrochemically active surface area (ESA) due to the increase in the particle size ii) decrease in the tafel slope potential in ORR and iii) increase in carbon corrosion. In this study, these properties were examined via accelerated degradation tests performed in CV and RDE. The catalysts having different Pt loadings, synthesized with different ink compositions, pH values and microwave durations were investigated. The commercial catalysts having Pt loadings of 20, 50 and 70 (wt %) were tried and best results were obtained for Pt/V (50 wt %) catalyst. Different carbon to Nafion&reg / ratios of 4, 8, 12 in the ink composition were tried. C/N ratio of 8 gave the best result in Pt dissolution and carbon corrosion degradation tests. The catalysts prepared at different pH values of 1.4, 6.25 and 10 were tried and the catalyst prepared at pH of 10 was less degraded in Pt dissolution test and the catalyst prepared at pH of 6.25 showed better resistance to carbon corrosion. Catalysts prepared under different microwave durations of 50, 60 and 120 s were tried and the catalyst prepared at 60 s gave the best performances.

This study aims to improve transportation held between six auction centers, Inter-Auction Transportation, of FloraHolland. FloraHolland serves ninety eight percent of the Dutch market and is the largest auction in floriculture industry. The company wants to give the best sale opportunities with the costs as low as possible and this is the main initiative of this study. In this line of thought, FloraHolland wants to have a improvement on its current routing and scheduling mechanism. Exact models do not work due to the complexity and the size of the problem. Therefore, we developed a two-stage approach specific to this study. With this approach, we split exact approach into two, a mathematical model followed by a heuristic. In the exact approach, trucks are routed and scheduled at the same time. On the other hand, our solution approach first determines most efficient routes to be followed with Cycle Assignment Model and then, with Scheduling Heuristic, trucks are assigned to the routes, so within day transportation is planned in detail. Overall, each stage of this approach works in harmony and brings good solutions in a short CPU time.

Weakening and liquefaction of sands with increasing excess pore water pressures under repeated loads is well-known. Occurrence of extensive damage to the built environment also at the sites underlain by fine soils during earthquakes have led the researchers to focus on the seismic response of such soils more recently. The primary objective of this study is to investigate the factors affecting cyclic behavior of saturated low-plastic fine soils through laboratory testing. An extensive laboratory testing program including conventional soil mechanics tests, consolidation tests, reconstituted sample preparation, monotonic and cyclic triaxial tests was carried out for this purpose. Laboratory program was conducted within two parts, one of which includes the tests performed with the silt specimens reconstituted in the laboratory and the other consisting of the tests performed with the undisturbed soil samples retrieved from Adapazari. The effects of the inherent soil properties and the effects of loading characteristics on the cyclic response of saturated low plastic silty soils were examined separately. Based on the test results, models were introduced (i) to predict the relationship between excess pore pressure ratio (ru), number of cycles (N) and cyclic stress ratio (CSRtx), (ii) to estimate the effect of initial shear stress on cyclic response, and (iii) to show the effects of initial void ratio (ei), initial shear stress ratio (

Three experimental studies were conducted to quantify the effects of system cycling, evaporator airflow, and condenser coil fouling on the performance of residential air conditioners. For all studies, the indoor dry-bulb (db) temperature was 80°F (26.7°C) db. The cycling study consisted of twelve transient tests conducted with an outdoor temperature of 95°F (35°C) db for cycle times of 6, 10, 15, and 24 minutes. Indoor relative humidities of 40%, 50%, and 60% were also considered. The evaporator airflow study consisted of twenty-four steady-state tests conducted with an indoor condition of 67°F (19.4°C) wet-bulb (wb) for evaporator airflows ranging from 50% below to 37.5% above rated airflow. Outdoor temperatures of 85°F (29.4°C) db, 95°F (35°C) db, and 105°F (40.6°C) db were also considered. The coil fouling study used a total of six condensers that were exposed to an outdoor environment for predetermined amounts of time and tested periodically. Three of the condensers were cleaned and retested during the periodic testing cycles. Testing consisted of thirty-three steady-state tests conducted with an indoor condition of 67°F (19.4°C) wb for outdoor exposure times of 0, 2000, 4000, and 8000 hours. Outdoor temperatures of 82°F (27.8°C) db and 95°F (35°C) db were also considered.

A global steady increase of energy consumption coupled with the decline of conventional oil resources points to a more aggressive exploitation of heavy oil. Heavy oil is a major source of energy in this century with a worldwide base reserve exceeding 2.5 trillion barrels. Management decisions and production strategies from thermal oil recovery processes are frequently based on reservoir simulation. A proper description of the physical properties, particularly oil viscosity, is essential in performing reliable modeling studies of fluid flow in the reservoir. We simulated cyclic steam injections on the highly viscous Hamaca oil, with a viscosity of over 10,000 cp at ambient temperature, and the production was drastically impacted by up to an order of magnitude when using improper mixing rules to describe the oil viscosity. This thesis demonstrates the importance of these mixing rules and alerts reservoir engineers to the significance of using different options simulators have built in their platforms to describe the viscosity of heavy oils. Log linear and power mixing rules do not provide enough flexibility to describe the viscosity of extra heavy oil with temperature. A recently implemented mixing rule in a commercial simulator has been studied providing satisfactory results. However, the methodology requires substantial interventions, and cannot be automatically updated. We provide guidelines to improve it and suggest more flexible mixing rules that could easily be implemented in commercial simulators. We also provide a methodology to determine the adequate time for each one of the periods in cyclic steam injection: injection, soaking and production. There is a lot of speculation in this matter and one of the objectives of this thesis is to better understand and provide guidelines to optimize oil production using proper lengths in each one of these periods. We have found that the production and injection periods should be similar in time length. Nevertheless, the production period should not be less than the injection period. On the other hand, the soaking period should be as short as possible because it is unproductive time in terms of field oil production for the well and therefore it translates into a negative cash flow for a company.

Three illustrative cases involving the electrodeposition of ultrathin metal films of varying reactivities onto noble-metal substrates were investigated: (i) Pd on Pt(111), a noble admetal on a noble-metal surface; (ii) Bi on Pd(111), a less noble admetal on a noble-metal surface; and (iii) Co on polycrystalline Pd and Pd(111), a reactive metal on a noble-metal surface. The interfacial electrochemistry of these prototypical systems was characterized using a combination of electrochemical methods (voltammetry and coulometry) and ultrahigh vacuum electron spectroscopies (Auger electron spectroscopy, AES; low energy electron diffraction, LEED; and X-ray photoelectron spectroscopy, XPS). Potential-controlled adsorption-desorption cycles of aqueous bromide exerted surface smoothening effects on ultrathin Pd films with defect sites (steps). This procedure, dubbed as electrochemical (EC) annealing, constituted a nonthermal analogue to conventional annealing. EC-annealed ultrathin Pd films exhibited long-range surface order and remained free of oxygen adspecies. Pdadatoms occupying step-sites were selectively dissolved and/or rearranged to assume equilibrium positions in a well-ordered (1x1) film. Electrodeposition of Co was found to be highly surface-structuresensitive. While virtually no Co electrodeposition transpired on a clean Pd(111) surface, Co was voltammetrically deposited on (i) a Pd(111) electrode roughened by oxidation-reduction cycles; and (ii) thermally annealed polycrystalline Pd, which is a composite of the (111) and (100) facets. Electrodeposition of Co was also observed to be kinetically hindered and slow potential scan rates (0.1 mV/s) were required. Well-defined ultrathin Bi films were potentiostatically electrodeposited onto Pd(111); a Stranski-Krastanov growth mode was indicated. The electrochemical reactivity of ultrathin Bi films was characterized using two surface probes: aqueous iodide and D-glucose. (i) Exposure of the prepared Bi adlayers (ΘBi 0.33) to aqueous iodide gave rise to (√3x√7) I-on-Bi superlattice. The same superlattice was obtained if Bi was electrodeposited onto Pd(111)(√3x√3)R30o-I. (ii) With respect to electrooxidation of D-glucose on Pd(111), the presence of Bi adlayers inhibited the by-product-induced "surface poisoning" of Pd(111) but reduced its electrocatalytic efficiency.

Cyanide-catalyzed aldimine coupling was employed to synthesize compounds with 1,2-ene-diamine and α-imine-amine structural motifs: 1,2,N,N'- tetraphenyletheylene-1,2-diamine (13) and (+/-)-2,3-di-(2-hydroxyphenyl)-1,2- dihydroquinoxaline (17), respectively. Single crystal X-ray diffraction provided solidstate structures and density functional theory calculations were used to probe isomeric preferences within this and the related hydroxy-ketone/ene-diol system. The enediamine and imine-amine core structures were calculated to be essentially identical in energy. However, additional effects-such as π conjugation-in 13 render an enediamine structure that is slightly more stable than the imine-amine tautomer (14). In contrast, the intramolecular hydrogen bonding present in 17 significantly favors the imine-amine isomer over the ene-diamine tautomer (18). Aldimine coupling (AIC) is the nitrogen analogue of the benzoin condensation and has been applied to dialdimines, providing the first examples of cyclizations effected by cyanide-catalyzed AIC. Sodium cyanide promoted the facile, intramolecular cyclization of several dialdimines in N,N-dimethylformamide, methanol, or dichloromethane/water (phase-transfer conditions) yielding a variety of six-membered heterocycles. Under aerobic conditions, an oxidative cyclization occurs to provide the diimine heterocycle. Cyanide-catalyzed aldimine coupling was employed as a new synthetic method for oligomerization. Nine rigidly spaced dialdimines were oxidatively coupled under aerobic conditions to yield conjugated oligoketimines and polyketimines with unprecedented structure and molecular weight (DP = 2 - 23, ~700 -8200 g/mol). The α- diimine linkage was established based on IR spectroscopy, NMR spectroscopy, size exclusion chromatography, and X-ray crystallographic characterization of the model oxidized dimer of N-benzylidene-(p-phenoxy)-aniline. Cyclic voltammetry indicates ptype electrical conductivity, suggesting they are promising candidates for plastic electronic devices. The cyanide-catalyzed benzoin condensation reaction of 4-substituted benzaldehydes followed by oxidation to the diketone, and the Schiff Base condensation of two equivalents of o-aminophenol provides 2,3-(4-X-phenyl)2-1,4-(2- hydroxyphenyl)2-1,4-diazabutadiene. The ligand is given the moniker X-dabphol. These ligands are readily metallated to form M-X-dabphol complexes. The copper complexes catalytically fix CO2 with propylene oxide to yield propylene carbonate. DFT studies along with a comparison with Hammet parameters help validate and elaborate on the catalytic cycle and the catalytic results obtained. The nickel complex is competent for olefin epoxidation. Synthesis, characterization, X-ray structure, DFT analysis, and catalytic activity of the parent nickel dabphol complex are reported.