Evaluating Risks of Dam-Reservoir Systems Using Efficient Importance Sampling

The occurrence frequency of failure events serve as critical indexes representing the safety status of dam-reservoir systems. Although overtopping is the most common failure mode with significant consequences, this type of event, in most cases, has a small probability. Estimation of such rare event risks for dam-reservoir systems with crude Monte Carlo (CMC) simulation techniques requires a prohibitively large number of trials, where significant computational resources are required to reach the satisfied estimation results. Otherwise, estimation of the disturbances would not be accurate enough. In order to reduce the computation expenses and improve the risk estimation efficiency, an importance sampling (IS) based simulation approach is proposed in this dissertation to address the overtopping risks of dam-reservoir systems. Deliverables of this study mainly include the following five aspects: 1) the reservoir inflow hydrograph model; 2) the dam-reservoir system operation model; 3) the CMC simulation framework; 4) the IS-based Monte Carlo (ISMC) simulation framework; and 5) the overtopping risk estimation comparison of both CMC and ISMC simulation. In a broader sense, this study meets the following three expectations: 1) to address the natural stochastic characteristics of the dam-reservoir system, such as the reservoir inflow rate; 2) to build up the fundamental CMC and ISMC simulation frameworks of the dam-reservoir system in order to estimate the overtopping risks; and 3) to compare the simulation results and the computational performance in order to demonstrate the ISMC simulation advantages. The estimation results of overtopping probability could be used to guide the future dam safety investigations and studies, and to supplement the conventional analyses in decision making on the dam-reservoir system improvements. At the same time, the proposed methodology of ISMC simulation is reasonably robust and proved to improve the overtopping risk estimation. The more accurate estimation, the smaller variance, and the reduced CPU time, expand the application of Monte Carlo (MC) technique on evaluating rare event risks for infrastructures.

THE LESSER-KNOWN PIANO CHAMBER MUSIC OF CAMILLE SAINT-SAENS: A RECORDING PROJECT

Throughout his long and industrious lifetime, Camille Saint-Saens (1835-1921) devoted himself unconditionally to music both as a composer and a performer. Saint-Saens was a self-described traditionalist and musical purist, yet his works are distinctly expressive and imaginative, and they reflect the composer's own unique musical language which incorporates recognizably modem traits such as chromaticism and frequent modulation. As a performer, Saint-Saens preferred to premiere his own works and often included his chamber music in his concert programs. Regarded primarily as a symphonic composer in the present day, however, his extensive and varied collection of chamber music works is sadly neglected. Six varied small-ensemble works with piano from his chamber music repertoire have been selected for study and recording for this project: Piano Trio No. 1 in F Major, Op. 18 (1864); Sonata for Cello and Piano No. 1 inC Minor, Op. 32 (1872); two pieces for two pianos, Le Rouet d'Omphale (The Spinning Wheel ofOmphale), Op. 31 (1871) and Phaeton, Op. 39 (1874); piano duet Konig Harald Haifagar (King Harald Haarfager), Op. 59 (1880); and a wind quartet, Caprice sur des airs Danois et Russes (Caprice on Danish and Russian Airs) for Flute, Oboe, Clarinet and Piano, Op. 79 (1887). Analyses of the forms and harmonic structures of these compositions will be included in this dissertation paper as well as studies from the viewpoint of Saint-Saens' compositional style, ensemble characteristics, and writing for the piano. The recordings for this project were made in four sessions in LeFrak Concert Hall at Queens College, the City University of New York. On September 24, 2003, Op. 31, Op. 39 and Op. 59 were recorded with Professor Morey Ritt, piano. On March 2, 2004, Op. 18 was recorded with Elena Rojas, violin, and Clare Liu, cello, and on March 15, 2004, Op. 32 was recorded, also with Ms. Liu. The Caprice, Op. 79 was recorded on June 27, 2008 with Laura Conwesser, flute; Randall Wolfgang, oboe; and Steve Hartman, clarinet. The recordings may be found on file in the library at the University of Maryland, College Park.