86,539 research outputs found
The Superposition Principle of Waves Not Fulfilled under M. W. Evans' O(3) Hypothesis
In 1992 M.W. Evans proposed a so-called O(3) symmetry of electromagnetic
fields by adding a constant longitudinal "ghost field" to the well-known
transversal plane em waves. He considered this symmetry as a new law of
electromagnetics. Later on, since 2002, this O(3) symmetry became the center of
his Generally Covariant Unified Field Theory which he recently renamed as ECE
Theory. One of the best-checked laws of electrodynamics is the principle of
linear superposition of electromagnetic waves, manifesting itself in
interference phenomena. Its mathematical equivalent is the representation of
electric and magnetic fields as vectors. By considering the superposition of
two phase-shifted waves we show that the superposition principle is
incompatible with M.W. Evans' O(3) hypothesis.Comment: 5 pages, no figure
Economics of Change in Market Structure, Conduct, and Performance The Baking Industry 1947-1958
Baking is one of the largest industries in the United States. Its sales, which exceed 1 out of every $10 spent by American consumers for food. Almost half of the domestic consumption of wheat flour is in the form of bread, rolls, cake, pie, doughnuts, sweet goods, and other perishable bakery products. While this study encompasses the perishable bakery products industry as defined by the U.S. Census Bureau, it focuses primarily on wholesale markets for white bread.
Since World War II, important changes have occurred in the bread baking industry. A decline in the per capita demand for bread products coupled with changes in technology and costs has affected the relationships between baking companies, their market behavior, and the resulting level of efficiency and price performance. In an industrial economy, the farming, milling, baking, retailing, and consuming functions are integrally related. Changes in the organization and practices in one may induce changes in others. The baking industry occupies a strategic position in this process, and as a result, consumers, farmers, millers, and retailers, as well as bakers themselves, have a vital interest in the way the baking industry performs.
Changes in market structure and firm behavior in the baking industry have been the subject of study and concern by several interested individuals and groups. The U.S. Department of Agriculture has followed with increased concern the widening of the market margin and the declining farmer share of consumer bread prices. The Senate Agricultural Committee has completed a study of average cost and returns of bakery operations.The Federal Trade Commission has followed the pricing practices of many baking companies with frequent cease and desist orders. I\u3e The Justice Department, through periodic prosecutions, has kept baking firms aware of the limitation imposed by the antitrust laws. The Senate Subcommittee on Antitrust and Monopoly has studied the impact of discriminatory pricing by large baking companies on small independent bakers.7 The industry has encouraged economic study of the historic development of baking and changes in market organization and practices.s Most recently, the F.T.C. studied buyer concentration and the integration of retail grocery organizations into baking and other food processing industries
Condensation transitions in a model for a directed network with weighted links
An exactly solvable model for the rewiring dynamics of weighted, directed
networks is introduced. Simulations indicate that the model exhibits two types
of condensation: (i) a phase in which, for each node, a finite fraction of its
total out-strength condenses onto a single link; (ii) a phase in which a finite
fraction of the total weight in the system is directed into a single node. A
virtue of the model is that its dynamics can be mapped onto those of a
zero-range process with many species of interacting particles -- an exactly
solvable model of particles hopping between the sites of a lattice. This
mapping, which is described in detail, guides the analysis of the steady state
of the network model and leads to theoretical predictions for the conditions
under which the different types of condensation may be observed. A further
advantage of the mapping is that, by exploiting what is known about exactly
solvable generalisations of the zero-range process, one can infer a number of
generalisations of the network model and dynamics which remain exactly
solvable.Comment: 23 pages, 8 figure
Factorised steady states for multi-species mass transfer models
A general class of mass transport models with Q species of conserved mass is
considered. The models are defined on a lattice with parallel discrete time
update rules. For one-dimensional, totally asymmetric dynamics we derive
necessary and sufficient conditions on the mass transfer dynamics under which
the steady state factorises. We generalise the model to mass transfer on
arbitrary lattices and present sufficient conditions for factorisation. In both
cases, explicit results for random sequential update and continuous time limits
are given.Comment: 11 page
Hard rod gas with long-range interactions: Exact predictions for hydrodynamic properties of continuum systems from discrete models
One-dimensional hard rod gases are explicitly constructed as the limits of
discrete systems: exclusion processes involving particles of arbitrary length.
Those continuum many-body systems in general do not exhibit the same
hydrodynamic properties as the underlying discrete models. Considering as
examples a hard rod gas with additional long-range interaction and the
generalized asymmetric exclusion process for extended particles (-ASEP),
it is shown how a correspondence between continuous and discrete systems must
be established instead. This opens up a new possibility to exactly predict the
hydrodynamic behaviour of this continuum system under Eulerian scaling by
solving its discrete counterpart with analytical or numerical tools. As an
illustration, simulations of the totally asymmetric exclusion process
(-TASEP) are compared to analytical solutions of the model and applied to
the corresponding hard rod gas. The case of short-range interaction is treated
separately.Comment: 19 pages, 8 figure
Spontaneous Symmetry Breaking in a Non-Conserving Two-Species Driven Model
A two species particle model on an open chain with dynamics which is
non-conserving in the bulk is introduced. The dynamical rules which define the
model obey a symmetry between the two species. The model exhibits a rich
behavior which includes spontaneous symmetry breaking and localized shocks. The
phase diagram in several regions of parameter space is calculated within
mean-field approximation, and compared with Monte-Carlo simulations. In the
limit where fluctuations in the number of particles in the system are taken to
zero, an exact solution is obtained. We present and analyze a physical picture
which serves to explain the different phases of the model
Criticality and Condensation in a Non-Conserving Zero Range Process
The Zero-Range Process, in which particles hop between sites on a lattice
under conserving dynamics, is a prototypical model for studying real-space
condensation. Within this model the system is critical only at the transition
point. Here we consider a non-conserving Zero-Range Process which is shown to
exhibit generic critical phases which exist in a range of creation and
annihilation parameters. The model also exhibits phases characterised by
mesocondensates each of which contains a subextensive number of particles. A
detailed phase diagram, delineating the various phases, is derived.Comment: 15 pages, 4 figure, published versi
An exactly solvable dissipative transport model
We introduce a class of one-dimensional lattice models in which a quantity,
that may be thought of as an energy, is either transported from one site to a
neighbouring one, or locally dissipated. Transport is controlled by a
continuous bias parameter q, which allows us to study symmetric as well as
asymmetric cases. We derive sufficient conditions for the factorization of the
N-body stationary distribution and give an explicit solution for the latter,
before briefly discussing physically relevant situations.Comment: 7 pages, 1 figure, submitted to J. Phys.
A propagation experiment for modelling high elevation angle land mobile satellite channels
This paper summarizes the results of a feasibility study for conducting high elevation angle propagation experiments in the European region for land mobile satellite communication. The study addresses various aspects of a proposed experiment. These include the selection of a suitable source for transmission, possibility of gathering narrow and wide band propagation data in various frequency bands, types of useful data, data acquisition technique, possible experimental configuration, and other experimental details
Exact solution of the zero-range process: fundamental diagram of the corresponding exclusion process
In this paper, we propose a general way of computing expectation values in
the zero-range process, using an exact form of the partition function. As an
example, we provide the fundamental diagram (the flux-density plot) of the
asymmetric exclusion process corresponding to the zero-range process.We express
the partition function for the steady state by the Lauricella hypergeometric
function, and thereby have two exact fundamental diagrams each for the parallel
and random sequential update rules. Meanwhile, from the viewpoint of
equilibrium statistical mechanics, we work within the canonical ensemble but
the result obtained is certainly in agreement with previous works done in the
grand canonical ensemble.Comment: 12 pages, 2 figure
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