2,934 research outputs found
Geometric erogdicity of a bead-spring pair with stochastic Stokes forcing
We consider a simple model for the
uctuating hydrodynamics of a
exible polymer
in dilute solution, demonstrating geometric ergodicity for a pair of particles that interact with each other through a nonlinear spring potential while being advected by a
stochastic Stokes
uid velocity field. This is a generalization of previous models which
have used linear spring forces as well as white-in-time
uid velocity fields.
We follow previous work combining control theoretic arguments, Lyapunov functions, and hypo-elliptic diffusion theory to prove exponential convergence via a Harris
chain argument. To this, we add the possibility of excluding certain "bad" sets in phase
space in which the assumptions are violated but from which the systems leaves with a
controllable probability. This allows for the treatment of singular drifts, such as those
derived from the Lennard-Jones potential, which is an novel feature of this work
The shape dynamics description of gravity
Classical gravity can be described as a relational dynamical system without
ever appealing to spacetime or its geometry. This description is the so-called
shape dynamics description of gravity. The existence of relational first
principles from which the shape dynamics description of gravity can be derived
is a motivation to consider shape dynamics (rather than GR) as the fundamental
description of gravity. Adopting this point of view leads to the question: What
is the role of spacetime in the shape dynamics description of gravity? This
question contains many aspects: Compatibility of shape dynamics with the
description of gravity in terms of spacetime geometry, the role of local
Minkowski space, universality of spacetime geometry and the nature of quantum
particles, which can no longer be assumed to be irreducible representations of
the Poincare group. In this contribution I derive effective spacetime
structures by considering how matter fluctuations evolve along with shape
dynamics. This evolution reveals an "experienced spacetime geometry." This
leads (in an idealized approximation) to local Minkowski space and causal
relations. The small scale structure of the emergent geometric picture depends
on the specific probes used to experience spacetime, which limits the
applicability of effective spacetime to describe shape dynamics. I conclude
with discussing the nature of quantum fluctuations (particles) in shape
dynamics and how local Minkowski spacetime emerges from the evolution of
quantum particles.Comment: 16 pages Latex, no figures, arXiv version of a submission to the
proceedings of Theory Canada
A finger mechanism for adaptive end effectors
This paper presents design and analysis of a rigid link finger, which may be suitable for a number of adaptive end effectors. The design has evolved from an industrial need for a tele-operated system to be used in nuclear environments. The end effector is designed to assist repair work in nuclear reactors during retrieval operation, particularly for the purpose of grasping objects of various shape, size and mass. The work is based on the University of Southampton's Whole Arm Manipulator, which has a special design consideration for safety and flexibility. The paper discusses kinematic issues associated with the finger design, and to the end of the paper specifies the limits of finger operating parameters for implementing control law
Fuzzy Linear Programming in DSS for Energy System Planning
Energy system planning requires the use of planning tools. The mathematical models of real-world energy systems are usually multiperiod linear optimization programs. In these models, the objective function describes the total discounted costs of covering the demand for final energy or energy services. The demand for various forms of energy or energy services is the driving force of the models. By using such linear programming (LP) formulations, decision makers can elaborate suitable strategies for solving their planning problems, such as the development of emission reduction strategies.
Uncertainties that affect the process of energy system planning can be divided into parameter and decision uncertainties. Data or parameter uncertainties can be addressed either by stochastic optimization or by the methodology of fuzzy linear programming (FLP). In addition, FLP allows explicit incorporation of decision uncertainties into a mathematical model.
This paper therefore aims at evaluating the methodology of FLP with respect to the support that it offers the decision-making process in energy system planning under uncertainty.
Employing the parallels between multi-objective linear programming (MOLP) and FLP, problems of FLP in decision support system applications are pointed out and solutions are offered. The proposed modifications are based on the methodology of aspiration-reservation based decision support and still enable modeling of uncertainties in a fuzzy sense. A case study is documented to show the application of the modified FLP approach
Automating Tolerance Synthesis: A Framework and Tools
This paper describes CASCADE-T—a new approach to tolerance synthesis that uses a complete representation of the conditional tolerance relations that exist between features of a part under design. Conditional tolerances are automatically determined from functional requirements and shape information. Tolerance primitives based on the virtual boundary requirements approach to tolerance representation are composed to form more complex tolerance relationships. Artificial intelligence techniques, including a constraint network, frame-based system, and dependency tracking are used to support flexible and detailed computation for tolerance analysis and synthesis
A FUZZY-BASED BUSINESS DECISION MAKING SYSTEM: FROM A MULTI-OBJECTIVE PERSPECTIVE
In order to provide essential managerial services for making critical business-biased decisions, there is need for accurate data. A business activity hinged on an effective administrative course of action will not only portray the manager of the business as adept but also help advance the financial interests of the organization, while minimizing its losses in this respect. In this paper, a decision making model for controlling business activities is developed, using a fusion of linear programming methods and a set of fuzzy membership functions. In the research conducted, it is revealed that: to improve the effectiveness of a model used for making multiple objective decisions for business related activities, the use of a fuzzy method is more effective than the use of a non-fuzzy method in minimizing the objective functions. It was also discovered that when computing the objective functions of a problem, a more precise result can be obtained by fortifying a linear programming model, with a technique for managing imprecise data
The status and programs of the New Relativity Theory
A review of the most recent results of the New Relativity Theory is
presented. These include a straightforward derivation of the Black Hole
Entropy-Area relation and its corrections; the derivation of the
string uncertainty relations and generalizations ; ; the relation between the
four dimensional gravitational conformal anomaly and the fine structure
constant; the role of Noncommutative Geometry, Negative Probabilities and
Cantorian-Fractal spacetime in the Young's two-slit experiment. We then
generalize the recent construction of the Quenched-Minisuperspace bosonic
-brane propagator in dimensions ( [18]) to the full
multidimensional case involving all -branes : the construction of the
Multidimensional-Particle propagator in Clifford spaces (-spaces) associated
with a nested family of -loop histories living in a target -dim
background spacetime . We show how the effective -space geometry is related
to curvature of ordinary spacetime. The motion of rigid
particles/branes is studied to explain the natural of classical
spin. The relation among -space geometry and , Finsler Geometry
and (Braided) Quantum Groups is discussed. Some final remarks about the
Riemannian long distance limit of -space geometry are made.Comment: Tex file, 21 page
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