65,157 research outputs found
Flood Routing on Small Streams: A Review of Muskingum-Cunge, Cascading Reservoirs, and Full Dynamic Solutions
Flood wave routing methods are adapted for small, naturally meandering streams. A simplified derivation of the Muskingum-Cunge equation is presented, based on Perumal and Kalinin-Milyukov's "characteristic reach length" concept. The derivation was extended to meandering streams, using the "parallel channels" analogy. "Cascading reservoirs", a second approximate method, is shown to be a special case of Muskingum-Cunge when properly formulated. Both approximate methods were evaluated against two "fully dynamic" solutions: the UNET-based solver in HEC-RAS and the National Weather Service's FLDWAV program. The four models were tested on four natural streams in northeastern Kansas. Detailed procedures for creating "equivalent reaches" were developed. The sensitivity of model stability was tested against variations in distance step size and other controls. HEC-RAS and FLDWAV gave nearly identical results for all the test reaches. The two approximate methods also performed well, but with deviations which are discussed. Recommendations were given for setting distance steps in fully dynamic solutions
Logic-Based Analogical Reasoning and Learning
Analogy-making is at the core of human intelligence and creativity with
applications to such diverse tasks as commonsense reasoning, learning, language
acquisition, and story telling. This paper contributes to the foundations of
artificial general intelligence by developing an abstract algebraic framework
for logic-based analogical reasoning and learning in the setting of logic
programming. The main idea is to define analogy in terms of modularity and to
derive abstract forms of concrete programs from a `known' source domain which
can then be instantiated in an `unknown' target domain to obtain analogous
programs. To this end, we introduce algebraic operations for syntactic program
composition and concatenation and illustrate, by giving numerous examples, that
programs have nice decompositions. Moreover, we show how composition gives rise
to a qualitative notion of syntactic program similarity. We then argue that
reasoning and learning by analogy is the task of solving analogical proportions
between logic programs. Interestingly, our work suggests a close relationship
between modularity, generalization, and analogy which we believe should be
explored further in the future. In a broader sense, this paper is a first step
towards an algebraic and mainly syntactic theory of logic-based analogical
reasoning and learning in knowledge representation and reasoning systems, with
potential applications to fundamental AI-problems like commonsense reasoning
and computational learning and creativity
Well-Terminating, Input-Driven Logic Programs
We identify a class of predicates for which termination does not depend on left-to-right execution. All that is required is that derivations are input-driven that is, in each derivation step, the input arguments of the selected atom do not become instantiated. The method of showing that a predicate is in that class is based on level mappings, closely following the traditional approach for LD derivations. Many predicates terminate under such weak assumptions. Knowing these predicates can be a very useful part of a more comprehensive method of showing termination, which would have to make more specific assumptions about the selection rule
A decidable subclass of finitary programs
Answer set programming - the most popular problem solving paradigm based on
logic programs - has been recently extended to support uninterpreted function
symbols. All of these approaches have some limitation. In this paper we propose
a class of programs called FP2 that enjoys a different trade-off between
expressiveness and complexity. FP2 programs enjoy the following unique
combination of properties: (i) the ability of expressing predicates with
infinite extensions; (ii) full support for predicates with arbitrary arity;
(iii) decidability of FP2 membership checking; (iv) decidability of skeptical
and credulous stable model reasoning for call-safe queries. Odd cycles are
supported by composing FP2 programs with argument restricted programs
A new 3D-beam finite element including non-uniform torsion with the secondary torsion moment deformation effect
In this paper, a new 3D Timoshenko linear-elastic beam finite element including warping torsion will be presented which is suitable for analysis of spatial structures consisting of constant open and hollow structural section (HSS) beams. The analogy between the 2ndorder beam theory (with axial tension) and torsion (including warping) was used for the formulation of the equations for non-uniform torsion. The secondary torsional moment deformation effect and the shear force effect are included into the local beam finite element stiffness matrix. The warping part of the first derivative of the twist angle was considered as an additional degree of freedom at the finite element nodes. This degree of freedom represents a part of the twist angle curvature caused by the bimoment. Results of the numerical experiments are discussed, compared and evaluated. The importance of the inclusion of warping in stress-deformation analyses of closed-section beams is demostrated
Eikonal equation of the Lorentz-violating Maxwell theory
We derive the eikonal equation of light wavefront in the presence of Lorentz
invariance violation (LIV) from the photon sector of the standard model
extension (SME). The results obtained from the equations of and
fields respectively are the same. This guarantees the
self-consistency of our derivation. We adopt a simple case with only one
non-zero LIV parameter as an illustration, from which we find two points. One
is that, in analogy with Hamilton-Jacobi equation, from the eikonal equation,
we can derive dispersion relations which are compatible with results obtained
from other approaches. The other is that, the wavefront velocity is the same as
the group velocity, as well as the energy flow velocity. If further we define
the signal velocity as the front velocity, there always exists a mode
with , hence causality is violated classically. Thus our method might be
useful in the analysis of Lorentz violation in QED in terms of classical
causality .Comment: 14 latex pages, no figure, final version for publication in EPJ
On Redundancy Elimination Tolerant Scheduling Rules
In (Ferrucci, Pacini and Sessa, 1995) an extended form of resolution, called
Reduced SLD resolution (RSLD), is introduced. In essence, an RSLD derivation is
an SLD derivation such that redundancy elimination from resolvents is performed
after each rewriting step. It is intuitive that redundancy elimination may have
positive effects on derivation process. However, undesiderable effects are also
possible. In particular, as shown in this paper, program termination as well as
completeness of loop checking mechanisms via a given selection rule may be
lost. The study of such effects has led us to an analysis of selection rule
basic concepts, so that we have found convenient to move the attention from
rules of atom selection to rules of atom scheduling. A priority mechanism for
atom scheduling is built, where a priority is assigned to each atom in a
resolvent, and primary importance is given to the event of arrival of new atoms
from the body of the applied clause at rewriting time. This new computational
model proves able to address the study of redundancy elimination effects,
giving at the same time interesting insights into general properties of
selection rules. As a matter of fact, a class of scheduling rules, namely the
specialisation independent ones, is defined in the paper by using not trivial
semantic arguments. As a quite surprising result, specialisation independent
scheduling rules turn out to coincide with a class of rules which have an
immediate structural characterisation (named stack-queue rules). Then we prove
that such scheduling rules are tolerant to redundancy elimination, in the sense
that neither program termination nor completeness of equality loop check is
lost passing from SLD to RSLD.Comment: 53 pages, to appear on TPL
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