In this study, a block manufacturing process is investigated using simulation as a tool to optimize resource utilization. First, the problem statement and the objectives of the study are established. Second, various data are collected by means of time studies, interviews, and physical observation of the operation. Activity durations are stripped and their distributions are obtained by using computer technology. When all required data are collected, STROBOSCOPE is used to create a model of the entire production process. The model is verified and validated to ensure that it performs as intended before running experiments. Results from experiments are analyzed by the use of spreadsheets and graphs. Recommendations with respect to the current operation and future changes are proposed. In both instances, the unit cost and the production rate are used as the criteria to determine the most effective resource usage. In conclusion, the minimization of production costs increases profit for manufacturers, reduces the construction cost for contractors, and results in lower prices to the end users. Note: for more information about required softwares to run the simulation and the animation, please contact: Julio C. Martinez, Ph.D., Assistant Professor of Civil Engineering (Construction), Virginia Tech, Blacksburg, VA 24061-0105, voice: (540) 231-9420, fax: (540) 231-7532, e-mail: julio@vt.edu, http://strobos.ce.vt.edu / Master of Science

The detection for phase locking in a forced oscillator with dual attractors and ill-defined phase structure is hard until a quantitative approach was constructed for detecting phase locking via stroboscopic method. We study the route to weak phase locking in a chaotic system ¡§Chua oscillator¡¨ with complex attractor structure by analyzing the stroboscopic points. The onset of weak phase locking detected by using this statistical approach and the critical coupling strength calculated by conditional Lyapunov exponent are matched well. Detailed structure of phase locking intensity is described by the Arnold tongue diagram. Moreover, we apply this approach on three hyper-chaotic systems with multi-scroll attractor, including hyper-chaotic Rössler system, hyper-chaotic Lorenz system, and modified MCK oscillator. The weak phase locking between hyper-chaotic system and a periodic or a chaotic driving force is observable following the condition of stroboscopic point concentration.

Due to technological innovations new materials are introduced to the construction industry from time to time and need to be installed properly by contractors. Based on their past experience, the contractors have some ideas on how to carry out the operation. However, those ideas are just a good starting point. In order to attain an efficient and productive operation, many issues need to be considered and clarified. To design a new construction operation, the designer needs to completely understand the processes, consider all relevant issues, and review all governing criteria. Achieving practical and productive operations for new technologies requires careful and thorough planning. Simulation modeling can be a very effective technique to design construction operations for new technologies. Simulation modeling allows experimenting with many of the factors involved in the operations prior to initial construction. Early construction sequencing can allow testing of many alternatives without expensive installations. Geosynthetics are currently being incorporated in flexible pavement systems to improve their performance. However, geosynthetics must be used in the correct application and installed properly in order to produce good results. One of the newly developed geosynthetics is geocomposite membrane that thought to provide strain energy absorption and a moisture barrier. This research discusses the application of discrete-event simulation (DES) to design and analyze the installation of geocomposite membranes in flexible pavements. Data collected from two test sections at the Virginia Smart Road in Blacksburg, Virginia was used for modeling and analysis. STROBOSCOPE, a programming language designed for modeling complex operations, was used as the simulation engine. The process used in the development of simulation models is discussed. A number of installation alternatives were studied and simulated to examine their practicality and to investigate their productivity, resource utilization, and unit cost. / Master of Science