No description available.

Call number: LD2668 .T4 1958 T43

Call number: LD2668 .T4 1959 E93

Mana computer programs have been developed for solving slope stability problems. Since slope stability problems can be characterized as optimization problems, many optimization techniques can be used for searching for the lowest safety factor for a given problem and the corresponding critical slip surface. Most of the slope stability programs use the direct search method which requires only the function value (i.e., safety factor value). In this thesis, a new optimization technique, the Broyden (1970), Fletcher (1970), Goldfarb (1970), and Shanno (1970) (BFGS) quasi-Newton optimization method, is used in conjunction with the STABR program of Lefebvre (1971) to solve slope stability problems. This method of optimization requires the function value and the first derivative value, which can be found by the finite difference method. A new program CSLIP3, incorporating the BFGS technique, is used to solve a variety of realistic slope stability problems. It is determined that CSLIP3 is reliable and efficient.

The calculation of a consolidation settlement is an important problem encountered in the foundation of buildings. Due to need for simplicity engineers are mainly using the one dimensional theory of Terzaghi for calculations of consolidation settlements with time. Consolidation tests are still performed in most laboratories with the traditional oedometer cell. Although the results of the oedometer can provide relatively reliable results, they are not equally effective for the calculation of the rate of consolidation. This primarily because of the inability of the oedometer cell to obtain full saturation of the sample. To ensure full saturation, back pressure must be applied which is not possible for conventional oedometer cell. The alternative use of the triaxial cell to examine the consolidation behavior of soils is discussed here.

The focus of this work was to develop a deeper understanding of the mechanisms of flame stabilization and extinction for shear layer stabilized, premixed flames. Planar experimental studies were performed in the attachment point region of an inner shear layer stabilized flame in an annular, swirl combustor. Through high resolution, simultaneous PIV & CH-PLIF measurements, the instantaneous flow field and flame position was captured enabling the characterization of 2D flame stretch and velocity conditions in the attachment point region. In addition, measurements performed at various equivalence ratios and premixer velocities provided insight into the physics governing blowoff. Most notably, these studies showed that as lean blowoff conditions are approached by decreasing equivalence ratio, the mean stretch rates near the attachment point decrease but remain positive throughout the measurement domain. In fact, compared to numerically calculated extinction stretch rates, the flame becomes less critically stretched as equivalence ratio is decreased. Also, investigation of the flame structure at the leading edge of the flame showed strong evidence that the flame is edge flame stabilized. This was supported by inspection of the CH-PLIF images, which showed the CH-layer oriented tangent to the flow field and terminating abruptly at the leading edge. Lastly, the flame anchoring location was observed to be highly robust as the mean flame edge flow conditions and mean location of leading edge of the flame were insensitive to changes in equivalence ratio, remaining nearly constant for values ranging from 0.9 to 1.1. However, at the leanest equivalence ratio of 0.8, the flame leading edge was located farther downstream and subject to much higher flow velocities. These results thus suggest that blowoff is the result of a kinematic balance and not directly from stretch induced flame extinction.

published_or_final_version / Applied Geosciences / Master / Master of Science

No description available.

The stability and boundedness theories are developed for impulsive differential equations with time delay. Definitions, notations and fundamental theory are presented for delay differential systems with both fixed and state-dependent impulses. It is usually more difficult to investigate the qualitative properties of systems with state-dependent impulses since different solutions have different moments of impulses. In this thesis, the stability problems of nontrivial solutions of systems with state-dependent impulses are ``transferred" to those of the trivial solution of systems with fixed impulses by constructing the so-called ``reduced system". Therefore, it is enough to investigate the stability problems of systems with fixed impulses. The exponential stability problem is then discussed for the system with fixed impulses. A variety of stability criteria are obtained and`numerical examples are worked out to illustrate the results, which shows that impulses do contribute to the stabilization of some delay differential equations. To unify various stability concepts and to offer a general framework for the investigation of stability theory, the concept of stability in terms of two measures is introduced and then several stability criteria are developed for impulsive delay differential equations by both the single and multiple Lyapunov functions method. Furthermore, boundedness and periodicity results are discussed for impulsive differential systems with time delay. The Lyapunov-Razumikhin technique, the Lyapunov functional method, differential inequalities, the method of variation of parameters, and the partitioned matrix method are the main tools to obtain these results. Finally, the application of the stability theory to neural networks is presented. In applications, the impulses are considered as either means of impulsive control or perturbations.Sufficient conditions for stability and stabilization of neural networks are obtained.

No description available.