Dynamic monitoring of structures is a method of detecting changes and damage to the structure. Vibration based monitoring has been used to detect damage in rotating machinery and is gaining ...popularity in the field of Structural Health Monitoring (SHM). Monitoring involves detecting changes in natural frequencies and changes in mode shapes. These changes reflect changes to properties of the bridge which can indicate damage. The Nibley Bridge is a single span bridge comprised of ten deck bulb girders. The bridge spans 25.91 m (85 ft.) and includes two lanes, sidewalks on both sides, and a small median. The Nibley Bridge was constructed with monitoring in mind. A dynamic monitoring system was planned to detect frequencies for long term monitoring. Initial monitoring of the embedded accelerometers was ineffective, so additional testing was required. An impact test was done with additional sensors to calibrate the embedded sensors. To further define the natural frequencies and mode shapes of the bridge, two shaker tests were also performed. The embedded sensors were noted as having a large noise range. Also, they required a specific datalogger to detect meaningful data. Recommendations for the use of the embedded accelerometers were determined and defined. The additional tests were able to assist in calibrating the accelerometers, as well as defining the natural frequencies and mode shapes of the structure. Natural frequencies were defined for each test and the changing condition of the bridge between those tests. The addition of asphalt occurred between two tests and a change of approximately 20° C between the other two tests. Though there is not much information to form a correlation, the detected changes define the dynamic aspects of the bridge. Lastly, mode shapes were determined and a Modal Assurance Criterion (MAC) analysis was done to correlate the measured and analytical mode shapes. This model helped to indicate which parameters effect the mode shapes of the structure. Comparison between these parameters and changes between them help to indicate the predicted behavior of the structure under different circumstances. Though these tests do not define all of the dynamic properties of the bridge, they do provide a general baseline of values that can be expected for future tests of the structure.
This study undertook the task of explaining one-night stands through Social Exchange Theory, specifically Interdependence Theory and the Investment Model of social exchange, wherein rewards and ...consequences are weighed amidst perceptions of rewards and costs in other relationships relative to what investment has been put into the current relationship. Rewards and costs associated with casual sex are discussed. It was hypothesized that various personality, attitudes, and other sex related constructs may predict one night stands based on how individuals appraise rewards, costs, and investment in commitment to relationships. Predictor variables were drawn from the following measures: The Big Five Inventory, the Short Form Love Attitudes Scale, the Sociosexual Orientation Inventory, the Sexual Attitudes and Feelings scale, and the Interpersonal Orientation scale. Correlation and logistic regression analyses showed that high sociosexuality, openness to experience, and erotic love style predicted having a one-night stand. Storge love style and positive stimulation predicted not engaging in such an act. Implications of these results are discussed in light of a one-night stand as a social exchange.
I present three models that examine the relationship between groups, where group members face some impediment to perfectly coordinating their actions. I present three distinct applications to the ...political economy of conflict. In the first, we study a coordination problem where two distinct groups of individuals are in competition with each other. One group (regime opponents) prefers a change in regime, and can participate in an attack which if sufficiently large, causes regime change. The other group (regime adherents) prefers the status quo and can support the regime, making it more resistant to attack. We derive and analyze the endogenous strength of the regime. We show how changes in the incentives of one group influence the coordination of the other. We isolate the coordinating effect of public information which results from the ''two-sidedness'' of the coordination problem, and show that coordination between regime adherents intensifies the already disproportionate effect of public information. Specifically, we show that public information affects the actions of individuals in each group identically, regardless of disparities in the quality of private information available to members of each group, implying that commonly observed sources of information will coordinate both regime adherents and regime opponents in exactly the same way. In the second, we begin with the observation that elites face a daunting coordination problem when contemplating a coup. Citizens, who desire political reform, face a similar coordination problem when contemplating protest. Since elites and citizens interact with the same leadership, these coordination problems are invariably linked. We develop a model which exploits this link to isolate an informational mechanism connecting popular protests and coups. Protests aggregate citizen information and provide elites with a public signal which helps them coordinate in a coup. We show that elites ''over-react'' to protest as a consequence of its publicity, and provide a microfounded explanation as to why elites use protests to facilitate coordination. Our model also suggests that protests in countries with media freedom better facilitate elite coordination. To test this, we examine how media freedom affects the relationship between protests and coups. The empirical analysis shows the effect of protests on coups is exacerbated in countries where media is free. In the third, mass killings are a tactic employed by some governments, presumably to reduce threats. We develop a theory that focuses on how the compliance decisions of repression agents tasked with carrying out atrocities affect the coordination dilemma of individuals contemplating rebellion, and subsequently, how the coordination problem of regime opponents induces a coordination problem between repression agents. We show that the effectiveness of mass killings, perceived through its lethality, has a positive relationship with the regime's ability to survive a rebellion. We then explore the role of strategic uncertainty at three levels: between regime opponents, between repression agents, and between regime opponents and repression agents. Finally, we explore implications that are relevant for the empirical study of mass killings.
We report the results of our first 2 years of experience with routine carotid angiography with an emphasis on technique and complications. We reviewed the hospital records, office charts, and ...prospective quality-assurance database records of 336 patients undergoing cerebrovascular arteriograms and collected data on the indications, complications, and technical aspects of the procedures. Indications for angiography included carotid stenosis in 331 (95%) patients, subclavian steal syndrome in 9 patients, vertebrobasilar insufficiency in 6 patients, and carotid body tumor in 2 patients. Selective catheterizations were performed on 654 common carotid arteries, 63 subclavian arteries, and 63 vertebral arteries. Both common carotid arteries were not selectively catheterized in 34 (9.8%) patients. Reasons for not selecting one or both common carotid arteries included physician choice to limit contrast administration in patients with renal insufficiency in 16 cases, proximal occlusion in 4 cases, proximal stenosis thought to be at risk of embolization if instrumented in 3 cases, imaging equipment malfunction in 2 cases, and in only 9 (2.6%) cases was selective carotid catheterization attempted but unsuccessful. There were no procedure-related deaths. Complications were documented in six (1.8%) patients, including cerebrovascular accident (CVA) in 1 (0.3%) patient. One hundred forty-two (41%) patients went on to carotid endarterectomy, and we performed 16 carotid bifurcation stents during the study period. Routine selective carotid angiography is a low-risk procedure that can be performed safely by vascular surgeons with catheter/guide wire skills.
Chalcogenide thin film resistor elements are being integrated with CMOS structures for nonvolatile memory applications. This paper reports on the first total dose and imprint data published on this ...new technology demonstrating no observable effects on chalcogenide films after exposure to 1 Mrad(Si) and 125/spl deg/C temperature.
Radiation testing was performed on three generations of commercial SONOS-based NROM flash memory products fabricated at technology nodes of 220 nm, 110 nm, and 90 nm. Neutron irradiation was ...investigated for mitigating latchup in these unhardened, commercial products. Although the behavior of the NROM memory technology appears to be consistent and well-behaved in radiation environments across multiple fabrication technologies and manufacturing technology nodes, existing commercial designs are incompatible with the requirements typically associated with space applications because of the sensitivities associated with the commercial CMOS underlayer and unhardened control circuitry.
The effect of dispersing discreet periclase (magnesium oxide) or brookite (titanium oxide) nanoparticles into poly(1-trimethylsilyl-1-propyne) (i.e., a super glassy polymer) and 1,2-polybutadiene ...(i.e., a rubbery polymer) has been examined. Particle dispersion has been investigated using atomic force microscopy and transmission electron microscopy to determine particle/aggregate size and distribution. Titanium dioxide nanoparticles dispersed into aggregates on the order of nanometers, as did magnesium oxide in 1,2-polybutadiene. However, the magnesium oxide filled poly(1-trimethylsilyl-1-propyne) did not exhibit nanoparticle aggregates below approximately one micron in characteristic dimensions. Nanocomposite transport properties were studied, where permeability and solubility coefficients were determined for light gases with increasing pressure, and diffusion coefficients were calculated from the solution-diffusion model. The permeability of light gases in the heterogeneous films increased with increasing particle loading. Depending on particle loading, brookite filled nanocomposite light gas permeability increased to over four times that of the unfilled polymer, whereas at high periclase loadings the nanocomposites exhibited light gas permeabilities in excess of an order of magnitude higher than the unfilled materials. Even at these high loadings the light gas selectivities were higher than predicted for films containing transmembrane defects. Solubility was relatively unaffected by the void volume concentration, although it did increase to some extent depending on the nanoparticle concentration. Wide angle X-ray diffraction, nuclear magnetic resonance, and Fourier transform infra-red experiments were used to determine if the nanoparticles remained stable during film preparation. TiO₂ nanoparticles did not appear to react with water, the polymer matrixes or test gases used in this research. However, under certain circumstances, periclase reacted with adventitious water to form brucite. A desilylation reaction occurred when brucite was exposed to polymers or small molecule compounds that contained a trimethylsilyl group attached to a conjugated organic backbone. This reaction caused certain disubstituted polyacetylenes to become insoluble in common organic solvents.
