Ultrasonic measurement of porosity in casts and welds

The development of a quantitative nondestructive method which involves ultrasonic attenuation measurements in frequency domain to determine volume fraction of porosity in aluminum cast is discussed. The aluminum alloy A357 casting samples were produced at the Ohio State University Foundry with controlled porosity contents ranging from 0% to 6%. A computer controlled system was used to direct ultrasonic beam to a test sample to different places to conduct ultrasonic attenuation measurements. The plot of attenuation coefficients as a function of frequency was then evaluated based on existing theories to determine volume fraction of porosity and pore size

Analytical results for the confinement mechanism in QCD_3

We present analytical methods for investigating the interaction of two heavy quarks in QCD_3 using the effective action approach. Our findings result in explicit expressions for the static potentials in QCD_3 for long and short distances. With regard to confinement, our conclusion reflects many features found in the more realistic world of QCD_4.Comment: 24 pages, uses REVTe

A terrestrial search for dark contents of the vacuum, such as dark energy, using atom interferometry

We describe the theory and first experimental work on our concept for searching on earth for the presence of dark content of the vacuum (DCV) using atom interferometry. Specifically, we have in mind any DCV that has not yet been detected on a laboratory scale, but might manifest itself as dark energy on the cosmological scale. The experimental method uses two atom interferometers to cancel the effect of earth's gravity and diverse noise sources. It depends upon two assumptions: first, that the DCV possesses some space inhomogeneity in density, and second that it exerts a sufficiently strong non-gravitational force on matter. The motion of the apparatus through the DCV should then lead to an irregular variation in the detected matter-wave phase shift. We discuss the nature of this signal and note the problem of distinguishing it from instrumental noise. We also discuss the relation of our experiment to what might be learned by studying the noise in gravitational wave detectors such as LIGO.The paper concludes with a projection that a future search of this nature might be carried out using an atom interferometer in an orbiting satellite. The apparatus is now being constructed

A proposed typology of online hate crime

Hate offenders and those convicted of ‘radical’ or ‘extremist’ terror-related offences have a well-established presence online, and hate incidents which occur in the real world are increasingly being linked to online ‘virtual’ activities (INCAH, 2010). Building on psychological research and theory, in particular McDevitt, Levin, and Bennett (2002), and Gerstenfeld, Grant, and Chang (2003), this study has developed an original typology of online hate offending, dividing it into four distinct types of user: Browsers, Commentators, Activists, and Leaders. In a partial test of this typology, an online search was conducted for hate incidents relating to a single London borough over seven months. The search uncovered a wide variety of online incidents. Content and thematic analysis supported the division of the typology into four distinct superordinate themes. Amendments to the typology and recommendations are then discussed

A program to develop a high-energy density primary battery with a minimum of 200 watt hours per pound of total battery weight third quarterly report, jan. - mar. 1965

Electrochemical study of prospective electrode- electrolyte systems for high-energy primary battery with minimum of 200 watt hours per pound of total battery weigh

Towards Quantum Superpositions of a Mirror: an Exact Open Systems Analysis

We analyze the recently proposed mirror superposition experiment of Marshall, Simon, Penrose, and Bouwmeester, assuming that the mirror's dynamics contains a non-unitary term of the Lindblad type proportional to -[q,[q,\rho]], with q the position operator for the center of mass of the mirror, and \rho the statistical operator. We derive an exact formula for the fringe visibility for this system. We discuss the consequences of our result for tests of environmental decoherence and of collapse models. In particular, we find that with the conventional parameters for the CSL model of state vector collapse, maintenance of coherence is expected to within an accuracy of at least 1 part in 10^{8}. Increasing the apparatus coupling to environmental decoherence may lead to observable modifications of the fringe visibility, with time dependence given by our exact result.Comment: 4 pages, RevTeX. Substantial changes mad

The Decline and (Possible) Renewal of Aspiration in the Clean Water Act

In the approximately four decades since Congress adopted sweeping amendments to the Federal Water Pollution Control Act—creating what is commonly known as the Clean Water Act (CWA)—the United States has made significant progress in reducing many kinds of water pollution. It is clear, however, that the United States has not attained the most ambitious of the statutory goals and objectives, including the overarching objective to “restore and maintain the chemical, physical, and biological integrity of the nation’s waters.”1 Indeed, although discrete water quality improvements continue in some places and for some forms of pollution, on a national scale progress toward the CWA’s goals has stalled in the past two decades. This Article explores several possible reasons for that failure. Those reasons include subversion of the statutory goals at the administrative, judicial, and legislative levels due to an imbalance in power between groups interested in how the law is implemented; the degree to which the statutory goals are perceived as unrealistic by those charged with implementation; and the potential that Congress intended those ambitious goals to serve as prods for as much progress as possible, but did not actually expect them to be achieved. The Article then proposes that significantly more progress can be made if we take advantage of available means of defining the ecological integrity of aquatic ecosystems more clearly and more precisely, using as examples biological water quality criteria, functional assessment methods for wetlands restoration and protection, and the use of real-world desired future condition definitions for watersheds. Better definition of what the somewhat imprecise statutory goals mean in the real world might help to overcome the apparent belief that those goals are impossible or infeasible to attain

A Unified Theory of Clean Water Act Jurisdiction

As it reaches its half century mark, the modern version of the federal Clean Water Act (CWA) remains a definitional quagmire. The U.S. Supreme Court, lower courts, and the two federal agencies charged with implementing the law have struggled to interpret its scope ever since its 1972 enactment. As a result, we still lack clarity regarding the most basic questions about the law’s reach. That causes massive uncertainty for regulated businesses and landowners, the federal and state agencies that implement the law, and members of the public Congress intended to protect. A unified interpretive approach focuses on the statutory text and its stated goals, considering the whole statute in context rather than individual terms construed in isolation. This analysis negates the inappropriate assumption that Congress was simply sloppy in its use of multiple terms to define the scope of various CWA programs. Rather, Congress adopted a nested set of scope terms to apply to different statutory provisions and purposes rather than a single definition applicable throughout the statute. Under this analysis, the CWA is not as limited by the concept of navigability as the Supreme Court has suggested in some cases. Read in the context of the whole statute, the term “navigable waters” extends beyond the traditional notion of navigability as reflected in cases such as The Daniel Ball. In the CWA, Congress designed multiple strategies, to be implemented by varying players, to achieve the broad and ambitious statutory objective and goals. The definitional terms applicable to each program, therefore, should be construed to effectuate the statutory goals Congress articulated for those programs in the text and structure of the whole statute