74,231 research outputs found
Can technology help solve the Arab-Israeli conflict in Palestine?
This repository item contains a single issue of Which Way?, a series of occasional papers published by The Frederick S. Pardee Center for the Study of the Longer-Range Future at Boston University. Which Way? pamphlets highlight emerging controversies at the crossroads where decisions must be made about choices that will affect the future of humankind through the twenty-first century and into the next. They are intended to illuminate, inform, arouse interest, and inspire debate among opinion-molders, decisionmakers, and an informed and thoughtful public.This paper looks at the lack of land in Palestine as one part of the problem that might have a low technology solution if the right pressures were applied. If the Gaza settlements were extended and Israel itself was built out into the eastern Mediterranean, then if a time came when peace was in reach, the struggle for land might not remain quite so desperate an issue. This is modeled after the “Dutch Solution,” in the hopes that their success could likewise be achieved using this obvious yet overlooked idea. Dr. Davidson encourages more practical collaboration between the academic sphere and those in positions to make change. Calling it “the quite unnecessary human tragedy in the Middle East,” he focuses on instances of past cooperation and exchange between the cultures of East and West. The paper also notes how, with technological vision, Death Valley was transformed into one of the most agriculturally productive regions in the United States. Dr. Davidson calls for greater real international support, pointing out the high tariffs of the U.S. and France on exports from North Africa which discourage economic expansion
The Indefinite Logarithm, Logarithmic Units, and the Nature of Entropy
We define the indefinite logarithm [log x] of a real number x>0 to be a
mathematical object representing the abstract concept of the logarithm of x
with an indeterminate base (i.e., not specifically e, 10, 2, or any fixed
number). The resulting indefinite logarithmic quantities naturally play a
mathematical role that is closely analogous to that of dimensional physical
quantities (such as length) in that, although these quantities have no definite
interpretation as ordinary numbers, nevertheless the ratio of two of these
entities is naturally well-defined as a specific, ordinary number, just like
the ratio of two lengths. As a result, indefinite logarithm objects can serve
as the basis for logarithmic spaces, which are natural systems of logarithmic
units suitable for measuring any quantity defined on a logarithmic scale. We
illustrate how logarithmic units provide a convenient language for explaining
the complete conceptual unification of the disparate systems of units that are
presently used for a variety of quantities that are conventionally considered
distinct, such as, in particular, physical entropy and information-theoretic
entropy.Comment: Manuscript of a 15 pp. review article. Suggestions for additional
appropriate references to relevant prior work are solicited from the
communit
The Burger Court—The First Ten Years
In this report we study estimation of time-delays in linear dynamical systems with additive noise. Estimating time-delays is a common engineering problem, e.g. in automatic control, system identification and signal processing. The purpose with this work is to test and evaluate a certain class of methods for time-delay estimation, especially with automatic control applications in mind. The class of methods consists of estimating the time-delay from the Laguerre transform of the input and output signals. The methods are evaluated experimentally with the aid of simulations and plots of approximation error, plots of original and Laguerre approximated input and output signals, plots of estimates, plots of RMS error, tables of ANOVA and plots of confidence intervals for different cases. The results are: Only certain input signals, e.g. steps, are useful. Systems with a not too fast dynamics give better estimation quality than pure time-delay systems despite the fact that the estimation methods were derived for pure time-delay systems. The Laguerre pole should be chosen in a certain way. The number of Laguerre functions should be as a high as possible
Evolutionary Effects of Irradiation in Cataclysmic Variables
The orbital evolution of cataclysmic variables in which the companion is
illuminated by a fraction of the accretion luminosity consists of
irradiation-driven limit cycles on thermal timescales, superimposed on a
secular evolution toward shorter periods due to systemic angular momentum
losses. We show that positive orbital period derivatives during bright phases
are a natural consequence of the expansion of the companion during high mass
transfer phases in the limit cycle. The irradiation instability may be enhanced
by consequential angular momentum losses, CAML, accompanying the limit cycle.
We investigate the secular evolution of cataclysmic binaries under the combined
effects of irradiation and CAML and show that faster than secular transfer
fluctuations that occur during these cycles can account for the observed
dispersion in disk luminosities or estimated accretion rates at a given orbital
period. If indeed irradiation-driven and CAML--assisted mass transfer
fluctuations on timescales faster than secular occur, as discussed in this
paper, then we may be able to predict the relative abundances of the different
types of cataclysmic variable at a given orbital period. For example this
mechanism may explain the relative paucity of dwarf novae with respect to
nova-like variables between 3 and 4 hours.Comment: 35 pages, AAS LATEX macros v4.0, 16 postscript figures, Accepted for
publication in the Astrophysical Journal; [email protected],
[email protected]
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