5,719 research outputs found
Stocks in the household portfolio: a look back at the 1990s
The growing prominence of stocks as a household asset in the 1990s encouraged the view that the United States had become a nation of zealous investors alert to every market development and eager to acquire new stocks. Yet an analysis of the factors behind the rise in the household equity share suggests that exceptionally high returns on stocks_rather than aggressive investment behavior_accounted for much of the increased importance of stocks.Financial markets ; Rate of return
Noise Pollution? What\u27s the solution?: Understanding Traffic Noise Pollution in Gettysburg, Pennsylvania
Noise pollution can be damaging to a community by impacting its atmosphere as well as the health of its residents, local quality of life, and local economy. Our study sought to gain insight into the level of noise pollution in Gettysburg, both in-town and on the Gettysburg College campus, and how noise pollution may be affecting the local residents and students. We selected 9 sampling sites, 6 in-town and 3 on the college campus, and measured the noise pollution in dBA with portable sound meters three days a week and three times a day over a three week period. Our data showed no major trends in terms of time of day or day of the week, but there were clear differences in noise pollution levels between the different sites in that town sites were generally louder than on campus sites. Noise pollution in town was often louder than 70 dBA, the noise threshold that indicates possible hearing damage overtime set by the World Health Organization. Gettysburg has recently enacted a noise ordinance; our study suggests the Borough possibly could do more to mitigate traffic noise by repairing roads and manipulating road design
Low-level estimation at high-levels of abstraction in system-level design
Embedded systems are becoming increasingly complex with shortening time-tomarket demands. System-level modeling and design have been proposed to help embedded system development keep pace with this complexity. In a system-level design environment, a designer is able to delay critical design decisions until late in the design cycle, reducing the risk of making incorrect decisions which could require a costly redesign. New methods of estimating system-level performance must be devised to accommodate these needs.;In embedded systems composed of off-the-shelf parts, performance can be roughly estimated using part documentation. However, this process can provide poor estimates. Additionally, if the design includes a custom part, there may not be detailed documentation from which to gather performance estimates. The exhaustive gathering of estimates is error prone and tedious. In this thesis we present a novel estimation technique called minimal characterization for creating system-level estimation metrics. We show that estimates can be orders of magnitude more accurate, without any loss in fidelity, using a small number of source-level metrics. We show results from applying a source-level performance estimation technique generally used on software systems to a system-level design that is implemented in both software and hardware targets. Finally, we present a categorization of secondary execution factors which can greatly affect the accuracy of system-level estimates but have only been peripherally addressed in other approaches
Constitutional Law - Search and Seizure - Duty of Home Owner to Permit Housing Inspection Without A Warrant
A Dayton, Ohio, city ordinance authorized housing inspectors to inspect any dwelling, without requiring a search warrant, for the purpose of safeguarding the public health and safety. Acting in compliance with the requirements of this ordinance, city housing inspectors requested admittance to appellant\u27s home in order to conduct a health inspection. Appellant refused to permit the inspectors to enter and inspect his home without a search warrant, and was therefore arrested and confined for violating the ordinance. Discharge of appellant in habeas corpus proceedings was reversed by the Ohio Court of Appeals. On appeal to the United States Supreme Court, held, affirmed by an equally divided Court, Ohio ex rel. Eaton v. Price, 364 U.S. 263 (1960)
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Next Generation Acoustic and Magnetic Devices for Radio Frequency Communication
This dissertation primarily focuses on utilizing low wave speed acoustic waves coupled with electromagnetics to increase performance of radio frequency front end architectures and reduce device dimensions. Chapter 1 begins with the history of communication technology beginning with Maxwell’s equations. Next brief introductions into the piezoelectricity, magnetism, and multiferroics are given to lay the groundwork for the following Chapters.Chapter 2 of this dissertation aims at improving the capability of communicating in lossy RF-denied media such as seawater. First, magnetic antennas are theoretically analyzed and compared to electric antennas showing that magnetic antennas perform better when surrounded by lossy conductive media. Next, a prototype multiferroic antenna is developed that uses piezoelectric PZT and magnetostrictive FeGa. The PZT applies a time varying stress to the FeGa causing the FeGa’s internal flux density to dynamically vary resulting in a time-varying magnetic near field. Magnetic near field measurements are compared to an analytical model showing good agreement.In Chapter 3 Lamb wave devices are investigated for filtering and frequency conversion applicationsin RF-front ends. Leveraging micro-fabrication techniques two Lamb wave delay lines are fabricated out of piezoelectric aluminum nitride (AlN). Interdigitated transducers (IDTs) are used to launch and receive Lamb waves as well as generate a time and space varying mechanical compliance. A circuit model is developed to compare to the experimental results and determine the magnitude of the compliance nonlinearity present in the AlN. Results show that acoustic devices can be developed that simultaneously filter and down-convert or up-convert a signal.Chapter 4 numerically analyzes strain tunable magnetic filters for applications in software defined radio and cognitive radio. For these applications filters with a tunable bandpass are necessary. The design relies on two CoFeB ellipses deposited on piezoelectric PMN-PT. An electric field is applied through the thickness of the PMN-PT resulting in a strain applied to the CoFeB ellipses. The electric field can be applied to either strain one ellipse or both ellipses. Straining both ellipses results in a tunable susceptibility from 6 GHz to 8 GHz, while straining only one ellipse results in a broadening of the bandpass response. These results show a potential solution for dynamic filters for next generation communication architectures
Motion artifact reduction of electrocardiograms using multiple motion sensors
An electrocardiogram (ECG) is a measurement of the electrical signal produced by the heart as it beats. This is a signal very commonly used by medical professionals, as it gives an indication of an individual’s heart rate and can further be used to detect specific abnormalities within the heart. There are a number of sources of noise that can corrupt the ECG signal, the most problematic being that of motion artifacts. As an individual wearing a surface ECG moves, their movements will add noise to the signal. This noise is particularly difficult to remove, as it will change depending on the movements of the user and will often fall in the same spectrum as the ECG signal itself.
The effectiveness of the adaptive filtering method in reducing motion artifacts is investigated using multiple motion sensors on key locations of the body and by combining the motion data through the use of various blind source separation methods. An adaptive filter is a filter that can use a reference signal in order to readjust itself to a constantly changing noise signal and is commonly used to clean ECG signals. The adaptive filter uses noise estimations based on the reference signal as well as previous noise estimations in order to continually clean the noisy signal. Since motion artifacts are based directly off the movements of the user, collected motion data will be directly correlated with the noise being introduced to the ECG, and can therefore be used in the adaptive filter to produce a desirable ECG signal
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