Vibratory Behavior of Rolling Element Bearings: a Lagrangian Approach

Vibratory behavior of a rolling element bearing on a horizontal rotor is studied in this work. This Thesis analyzes the dynamics of a typical roller bearing as a result of internal excitations. These internal excitations stem from the geometric deviations of the interacting surfaces from their ideal geometry. Such deviations in turn are the results of either manufacturing limitations or normal wear of the bearing surfaces. Lagrangian approach is implemented to derive the dynamic equations of motion. Matlab is used to solve the equation of motion of governing the vibrations of the system. Parametric studies are conducted to provide results for several excitation levels. The study shows, that for a surface waviness of 0.00001 (mm), the roller\u27s radial displacement is about 1.5*10-6 (mm) under a linear analysis for a shaft speed of 2000rpm. Consideration of non-linear analysis predicted 2*10-15 (mm) for the roller radial displacement in response to the same surface condition. For shaft speeds of 2400 rpm, 3000 rpm, and 4000 rpm, the roller radial displacements for linear analysis are 8.5*10-7, 8*10-7, and 6*10-7 (mm) respectively. And for nonlinear analysis are 8*10-15, 2*10-16, 6*10-16 respectivel

Vibratory Behavior of Rolling Element Bearings: a Lagrangian Approach

Vibratory behavior of a rolling element bearing on a horizontal rotor is studied in this work. This Thesis analyzes the dynamics of a typical roller bearing as a result of internal excitations. These internal excitations stem from the geometric deviations of the interacting surfaces from their ideal geometry. Such deviations in turn are the results of either manufacturing limitations or normal wear of the bearing surfaces. Lagrangian approach is implemented to derive the dynamic equations of motion. Matlab is used to solve the equation of motion of governing the vibrations of the system. Parametric studies are conducted to provide results for several excitation levels. The study shows, that for a surface waviness of 0.00001 (mm), the roller\u27s radial displacement is about 1.5*10-6 (mm) under a linear analysis for a shaft speed of 2000rpm. Consideration of non-linear analysis predicted 2*10-15 (mm) for the roller radial displacement in response to the same surface condition. For shaft speeds of 2400 rpm, 3000 rpm, and 4000 rpm, the roller radial displacements for linear analysis are 8.5*10-7, 8*10-7, and 6*10-7 (mm) respectively. And for nonlinear analysis are 8*10-15, 2*10-16, 6*10-16 respectivel

Recovery of materials from recycling of spent furnace linings

The objective of this research study is to evaluate the technical feasibility of liberating metal entrapped in the spent melting furnace linings obtained from a non-ferrous metal producer and develop an economic technique to recycle all of the materials presently landfilled. Five to six million pounds of spent melting furnace linings are landfilled annually from this non-ferrous producer --Abstract, page iii

Computational study of pristine and titanium-doped sodium alanates for hydrogen storage applications

The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained unanswered regarding the role of Ti in reversible hydrogen storage of sodium alanates with improved thermodynamics and kinetics of hydrogen desorption. The first question is about the position of transition metal dopants in the sodium aluminum hydride lattice. The position is investigated by identifying the possible sites for titanium dopants in NaAlH4 lattice and studying the structure and dynamics of possible compounds resulting from titanium doping in sodium alanates. The second question is the role of titanium dopants in improved thermodynamics of hydrogen desorption in Ti-doped NaAlH4. Though it is accepted in the literature that formation of TiAl alloys (Ti-Al and TiAl3) is favorable, reaction pathways are not clearly established. Furthermore, the source of aluminum for Ti-Al alloy formation is not clearly understood. The third question in this area is the role of titanium dopants in improved kinetics of hydrogen absorption and desorption in Ti-doped sodium alanates. This study is directed towards addressing the three longstanding questions in this area. Thermodynamic and kinetic pathways for hydrogen desorption in pristine NaAlH4 and formation of Ti-Al alloys in Ti-doped NaAlH 4, are elucidated to understand the underlying mechanisms of hydrogen desorption. Density functional theory formalism as implemented in CASTEP (Cambridge Serial Total Energy Package) is used to study the structure and energetics of pristine and Ti-doped sodium alanates. From investigations of various models of sodium alanates with Ti dopants, it is shown that the difference between the energy required for Ti→SNa (Ti-substituted Na at the lattice site on the surface) and Ti→TI (Ti placed on top of the surface interstitial SI site) is 0.003 eV atom-1, and is minimal compared to other models. Since less energy is required for Ti→S Na and Ti→TI, these two sites (SNa and T I) would be preferred by the Ti dopants. In Ti→SNa model, Ti is coordinated to two aluminum and seven hydrogen atoms resulting in the possible formation of a TiAl2H7 complex. At elevated temperatures (423 and 448 K), the number of aluminum atoms coordinating with titanium in the complex increase from two (at distances in the 2.6-2.7 Å range) to five (at distances in the 2.6-2.7 Å range). Besides the formation of a Ti-Al-H complex, Al-Al association (with a 2.97 Å bond length) is also seen from the DFT-MD results. In the case of Ti→TI, Ti is coordinated to two aluminum and two hydrogen atoms resulting in the possible formation of a TiAl2H2 complex. TiAl2 H2 complex becomes TiAl3H6 and TiAl 3H7 at elevated temperatures of 423 and 448 K, respectively. The investigation of thermodynamics pathways in Ti-doped sodium alanates illustrates a three step reaction pathway to the formation of TiAl3 (Ti and AlH3 after the first reaction, TiAl after the second and finally TiAl3). This investigation also suggests aluminum in its +3 oxidation state present in aluminum hydride species is responsible in the formation of Ti-Al alloys. From kinetics studies, the proposed mechanism is related to transition from AlH4- to AlH6 3-. The rate limiting step is determined to be associated with hydrogen evolution from association of AlH3 species nucleating aluminum phase. This step is 15 kJ/mol higher than the nearest highest barrier in the reaction path related to transition from AlH52- to AlH63-. From the DFT-MD simulations, it is observed that the titanium dopants are present on the surface during the entire simulation time and exhibit the role in catalytic splitting of hydrogen from surrounding AlH4groups. Besides the catalytic role, Ti dopants also form bonds with Al, and we also see that the AlH4 groups on the surface and that are present in the sub-surface layers are drawn towards the Ti dopants. This association of Al around titanium indicates the initiation of Al nucleation site facilitated by Ti dopants residing on the surface

Advanced Applications Of Big Data Analytics

Human life is progressing with advancements in technology such as laptops, smart phones, high speed communication networks etc., which helps us by reducing load in doing our daily activities. For instance, one can chat, talk, make video calls with his/her friends instantly using social networking platforms such as Facebook, Twitter, Google+, WhatsApp etc. LinkedIn, Indeed, etc., connects employees with potential employers. The number of people using these applications are increasing day-by-day, and so is the amount of data generated from these applications. Processing such vast amounts of data, may require new techniques for gaining valuable insights. Network theory concepts form the core of such techniques that are designed to uncover valuable insights from large social network datasets. Many interesting problems such as ranking top-K nodes and top-K communities that can effectively diffuse any given message into the network, restaurant recommendations, friendship recommendations on social networking websites, etc., can be addressed by using the concepts of network centrality. Network centrality measures such as In-degree centrality, Out-degree centrality, Eigen-vector centrality, Katz Broadcast centrality, Katz Receive centrality, and PageRank centrality etc., comes handy in solving these problems. In this thesis, we propose different formulae for computing the strength for identifying top-K nodes and communities that can spread viral marketing messages into the network. The strength formulae are based on Katz Broadcast centrality, Resolvent matrix measure and Personalized PageRank measure. Moreover, the effects of intercommunity and intracommunity connectivity in ranking top-K communities are studied. Top-K nodes for spreading any message effectively into the network are determined by using Katz Broadcast centrality measure. Results obtained through this technique are compared with the top-K nodes obtained by using Degree centrality measure. We also studied the effects of varying α on the number of nodes in search space. In Algorithms 2 and 3, top-K communities are obtained by using Resolvent matrix and Personalized PageRank measure. Algorithm 2 results were studied by varying the parameter α

Immunoglobulin G4-related disease - diagnostic dilemma and importance of clinical judgement: a case report

Immunoglobulin G4 (IgG4)-related disease is a multi-organ, immune-mediated, fibro-inflammatory disorder characterized by tumefactive masses in the affected organs. Incidence and prevalence of IgG4-related disease (RD) are not clearly known and have slight male preponderance. It often involves multiple organs at the time of presentation or over the course of disease mimicking malignancy, Sjogren's syndrome, antineutrophil cytoplasmic antibodies associated vasculitis, infections. A thorough workup is needed to rule out these mimickers. A 33-year-old gentleman presented to us with history of progressive swelling in the right peri-orbital region for four years. On evaluation, abdominal imaging was notable for the sausage-shaped pancreas and hypoenchancing nodules in bilateral kidneys. Histological examination of right lacrimal gland revealed lymphoplasmacytic infiltrate and storiform fibrosis. Serum IgG4 levels were normal, and immunostaining was negative. A diagnosis of IgG4-RD was suggested because of multi-organ involvement, classical radiological and histopathological features. Awareness about IgG4-RD, an under-recognized entity is essential, as it is treatable, and early recognition may help in a favourable outcome. Appropriate use of clinicopathological, serological and imaging features in the right clinical context may help in accurate diagnosis. Elevated serum IgG4 levels and biopsy are not mandatory for the diagnosis