Probabilistic Analysis of Slide-Rocking Structures Under Earthquake Loads

Estimates of rare seismic hazard are essential for the resilience of critical infrastructure and facilities. However, these estimates are highly uncertain at long return periods due to the lack of observed earthquake records. Several ground motion prediction equations have been proposed to close this gap and estimate rare seismic demands; however, these models were developed based on more moderate earthquake records and can yield physically unrealizable ground motions when extrapolated to long return periods. For this reason, seismologists have proposed using precariously balanced rocks (PBRs) as a way to constrain rare seismic hazard. PBRs are a type of fragile geologic structure whose upright existence indicates that a seismic event powerful enough to cause the structure to overturn has not yet occurred. PBRs are individual or stacks of freestanding rocks that tend to respond in rigid body modes, such as rocking and sliding, when subjected to earthquake loads. The behavior of these freestanding structures is very sensitive to small changes in geometry, position, and ground motion characteristics. As a result, reliable probabilistic relationships for the seismic response of freestanding structures are lacking. To this end, this thesis aims to rigorously evaluate and identify a robust probabilistic relationship between the intensity of a ground motion and the dynamic behavior of freestanding structures, including both rocking and sliding demands, such that PBRs can be used to constrain seismic hazard. The dynamic response of freestanding structures is modeled analytically via two-dimensional equations of motion. Various ground motion intensity measures are evaluated in both scalar and vector forms to identify an optimal predictor of structural response. After thorough analysis, a vector combination of Cumulative Absolute Velocity and Response Spectrum Intensity is selected. This relationship is then used in a case study to demonstrate the applicability of the vector intensity measure in a PBR analysis and comparison with current seismic hazard in the New Madrid Seismic Zone. Advisor: Christine E. Wittic

Video Guidance, Landing, and Imaging system (VGLIS) for space missions

The feasibility of an autonomous video guidance system that is capable of observing a planetary surface during terminal descent and selecting the most acceptable landing site was demonstrated. The system was breadboarded and "flown" on a physical simulator consisting of a control panel and monitor, a dynamic simulator, and a PDP-9 computer. The breadboard VGLIS consisted of an image dissector camera and the appropriate processing logic. Results are reported

Efficient Intensity Measures of Slide-Rocking Structures for Precariously Balanced Rocks

Precariously balanced rocks (PBRs) and other fragile geologic features are important in both the engineering and seismological communities since they are indicative of the maximum ground motion at a site over the rock’s lifetime. Precariously balanced rocks are individual or stacks of freestanding rocks that tend to respond in rigid body modes when subject to seismic excitation – namely, rocking, sliding, slide-rocking, and free-flight, which can lead to overturning. The seismic response of freestanding structures, such as PBRs, is known to be extremely sensitive to small changes in geometry, position, and earthquake excitation. As such, deterministic methods are limited in their application to PBRs and reliable probabilistic relationships are necessary. Previous probabilistic studies on freestanding structures and PBRs have focused on a single response mode, such as overturning, and utilized a single intensity measure, typically the peak ground acceleration. To this end, this paper aims to identify optimal ground motion intensity measures (IMs) that correlate well with the multiple possible rigid body modes including rocking and sliding. In this study, structural parameters, including geometry and friction, were varied to induce each of the fundamental rigid body modes. The response of each structure was simulated to 3750 analytical pulse motions through numerical integration of the slide-rocking equations of motion within MATLAB. The results of the simulations were statistically analyzed to determine the optimal IMs in terms of both sufficiency and efficiency. A set of viable IMs are presented that have more robust probabilistic relationships with the dynamic response of a sliding or rocking block compared to previous IM studies

Video guidance, landing, and imaging systems

The adaptive potential of video guidance technology for earth orbital and interplanetary missions was explored. The application of video acquisition, pointing, tracking, and navigation technology was considered to three primary missions: planetary landing, earth resources satellite, and spacecraft rendezvous and docking. It was found that an imaging system can be mechanized to provide a spacecraft or satellite with a considerable amount of adaptability with respect to its environment. It also provides a level of autonomy essential to many future missions and enhances their data gathering ability. The feasibility of an autonomous video guidance system capable of observing a planetary surface during terminal descent and selecting the most acceptable landing site was successfully demonstrated in the laboratory. The techniques developed for acquisition, pointing, and tracking show promise for recognizing and tracking coastlines, rivers, and other constituents of interest. Routines were written and checked for rendezvous, docking, and station-keeping functions

An evolutionary stage model of outsourcing and competence destruction : a Triad comparison of the consumer electronics industry

Outsourcing has gained much prominence in managerial practice and academic discussions in the last two decades or so. Yet, we still do not understand the full implications of outsourcing strategy for corporate performance. Traditionally outsourcing across borders is explained as a cost-cutting exercise, but more recently the core competency argument states that outsourcing also leads to an increased focus, thereby improving effectiveness. However, no general explanation has so far been provided for how outsourcing could lead to deterioration in a firm‟s competence base. We longitudinally analyze three cases of major consumer electronics manufacturers, Emerson Radio from the U.S., Japan‟s Sony and Philips from the Netherlands to understand the dynamic process related to their sourcing strategies. We develop an evolutionary stage model that relates outsourcing to competence development inside the firm and shows that a vicious cycle may emerge. Thus it is appropriate to look not only at how outsourcing is influenced by an organization‟s current set of competences, but also how it alters that set over time. The four stages of the model are offshore sourcing, phasing out, increasing dependence on foreign suppliers, and finally industry exit or outsourcing reduction. The evolutionary stage model helps managers understand for which activities and under which conditions outsourcing across borders is not a viable option. Results suggest that each of these firms had faced a loss of manufacturing competitiveness in its home country, to which it responded by offshoring and then outsourcing production. When a loss of competences occurred, some outsourcing decisions were reversed

Forecasting and Monitoring Intense Thunderstorms in the Hindu Kush Himalayan Region: Preliminary Results from Spring 2018 Demonstration (P2-14)

No abstract availabl

Forecasting and Monitoring Intense Thunderstorms in the Hindu Kush Himalayan Region: Spring 2018 Forecasting Experiment

Some of the most intense thunderstorms on the planet occur in the Hindu Kush Himalayan (HKH) region of South Asia - where many organizations lack the capacity needed to predict, observe and/or effectively respond to the threats associated with high-impact convective weather. Among the hazards include tornadoes, damaging straight-line winds (known as Nor'westers in the HKH region), large hail, and flash flooding, which typically peak in the pre-wet-monsoon season. Previous studies have documented a disproportionately large number of casualties associated with intense thunderstorms in this region; therefore, the goal of this project is to increase situational awareness of these hazards through short-term modeling and satellite assessment tools

Thermoplastic Green Machining for Textured Dielectric Substrate for Broadband Miniature Antenna

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65902/1/j.1551-2916.2005.00089.x.pd