3,590 research outputs found
Ceramic processing: Experimental design and optimization
The objectives of this paper are to: (1) gain insight into the processing of ceramics and how green processing can affect the properties of ceramics; (2) investigate the technique of slip casting; (3) learn how heat treatment and temperature contribute to density, strength, and effects of under and over firing to ceramic properties; (4) experience some of the problems inherent in testing brittle materials and learn about the statistical nature of the strength of ceramics; (5) investigate orthogonal arrays as tools to examine the effect of many experimental parameters using a minimum number of experiments; (6) recognize appropriate uses for clay based ceramics; and (7) measure several different properties important to ceramic use and optimize them for a given application
The rigged Hilbert space approach to the Lippmann-Schwinger equation. Part I
We exemplify the way the rigged Hilbert space deals with the
Lippmann-Schwinger equation by way of the spherical shell potential. We
explicitly construct the Lippmann-Schwinger bras and kets along with their
energy representation, their time evolution and the rigged Hilbert spaces to
which they belong. It will be concluded that the natural setting for the
solutions of the Lippmann-Schwinger equation--and therefore for scattering
theory--is the rigged Hilbert space rather than just the Hilbert space.Comment: 34 pages, 1 figur
The Importance of Boundary Conditions in Quantum Mechanics
We discuss the role of boundary conditions in determining the physical
content of the solutions of the Schrodinger equation. We study the
standing-wave, the ``in,'' the ``out,'' and the purely outgoing boundary
conditions. As well, we rephrase Feynman's prescription as a
time-asymmetric, causal boundary condition, and discuss the connection of
Feynman's prescription with the arrow of time of Quantum
Electrodynamics. A parallel of this arrow of time with that of Classical
Electrodynamics is made. We conclude that in general, the time evolution of a
closed quantum system has indeed an arrow of time built into the propagators.Comment: Contribution to the proceedings of the ICTP conference "Irreversible
Quantum Dynamics," Trieste, Italy, July 200
The role of the rigged Hilbert space in Quantum Mechanics
There is compelling evidence that, when continuous spectrum is present, the
natural mathematical setting for Quantum Mechanics is the rigged Hilbert space
rather than just the Hilbert space. In particular, Dirac's bra-ket formalism is
fully implemented by the rigged Hilbert space rather than just by the Hilbert
space. In this paper, we provide a pedestrian introduction to the role the
rigged Hilbert space plays in Quantum Mechanics, by way of a simple, exactly
solvable example. The procedure will be constructive and based on a recent
publication. We also provide a thorough discussion on the physical significance
of the rigged Hilbert space.Comment: 29 pages, 2 figures; a pedestrian introduction to the rigged Hilbert
spac
A sensor technology survey for a stress aware trading process
The role of the global economy is fundamentally important to our daily lives. The stock markets reflect the state of
the economy on a daily basis. Traders are the workers within the stock markets who deal with numbers, statistics, company analysis, news and many other factors which influence the economy in real time. However, whilst making significant decisions within their workplace, traders must also deal with their own emotions. In fact, traders have one of the most stressful professional occupations. This survey merges current knowledge about stress effects and sensor technology by reviewing, comparing, and highlighting relevant existing research and commercial products that are available on the market. This assessment is made in order to establish how sensor technology can support traders to avoid poor decision making during the trading process. The purpose of this article is: 1) to review the studies about the impact of stress on the decision making process
and on biological stress parameters that are applied in sensor design; 2) to compare different ways to measure stress by using sensors currently available in the market according to basic biometric principles under trading context; and 3) to suggest new directions in the use of sensor technology in stock markets
Robot’s weight distribution influence on angular momentum produced by a standing vertical jump
Vertical jump movement generators usually apply the ZMP (Zero Moment Point) and/or angular momentum equations as restrictions when planning the movements of the robot joints, which can cause undesired oscillations in the torso, compromise accuracy of the jump and/or complicate the search for online solutions. This paper presents a strategy to solve the problem related to angular momentum generated by the movement of the vertical jump, performed by a robot with 3 DoF (Degree of Freedom) and 4-links. Mentioned links correspond to the following parts of the human body: foot, leg, thigh and torso, and its weighted mass distribution and CoM (Center of Mass) position define an angular momentum profile within a specified range of speed values for the jump. In order for that to happen, simulations were performed using MATLAB, considering homogeneous and weighted distributions of total mass between the links of a robot and applying a third-degree polynomial function for the vertical acceleration curve of the CoM. The results suggest that based on the strategy proposed in this paper, it is possible to perform a vertical jump with dynamically stable movements and with angular moment near zero, and, at the same time, minimizing the problems presented in some prior methods. © 2016 IEEE.Vertical jump movement generators usually apply the ZMP (Zero Moment Point) and/or angular momentum equations as restrictions when planning the movements of the robot joints, which can cause undesired oscillations in the torso, compromise accuracy of the14416691676sem informaçãosem informaçã
F-transforms for the definition of contextual fuzzy partitions
Fuzzy partitions can be defined in many different ways, but usually, it is done taking into account the whole universe. In this paper, we present a method to define fuzzy partitions according to those elements in the universe holding certain fuzzy attribute. Specifically, we show how to define those fuzzy partitions by means of F-transforms.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
This work has been partially supported by the Spanish Ministry of Science by the projects TIN15-70266-C2-P-1 and TIN2016-76653-
High Angular Resolution Observations of the Collimated Jet Source Associated with a Massive Protostar in IRAS 16547-4247
A triple radio source recently detected in association with the luminous
infrared source IRAS 16547-4247 has been studied with high angular resolution
and high sensitivity with the Very Large Array at 3.6 and 2 cm. Our
observations confirm the interpretation that the central object is a thermal
radio jet, while the two outer lobes are most probably heavily obscured HH
objects. The thermal radio jet is resolved angularly for the first time and
found to align closely with the outer lobes. The opening angle of the thermal
jet is estimated to be , confirming that collimated outflows can
also be present in massive protostars. The proper motions of the outer lobes
should be measurable over timescales of a few years. Several fainter sources
detected in the region are most probably associated with other stars in a young
cluster.Comment: 9 pages, 2 figure
Bibliografía usada en la formación matemática del profesorado de infantil
Para realizar el estudio se escogió una muestra de 13 universidades españolas en las que se imparte la titulación y cuyas guías docentes son accesibles desde sus páginas webs. Se descargaron todas las guías docentes y se pasó la información a una base de datos ad hoc. Se realizó un proceso de estandarización de los nombres y de las referencias porque para cada asignatura utilizan formatos distintos incluso en la misma universidad. Se obtuvieron 493 referencias, que se presentan como bibliografía básica, específica, recomendada o complementaria. Posteriormente se hicieron conteos de frecuencias de cada autor, referencia y año para determinar la antigüedad de las mismas
Statistical mechanical theory of an oscillating isolated system. The relaxation to equilibrium
In this contribution we show that a suitably defined nonequilibrium entropy
of an N-body isolated system is not a constant of the motion in general and its
variation is bounded, the bounds determined by the thermodynamic entropy, i.e.,
the equilibrium entropy. We define the nonequilibrium entropy as a convex
functional of the set of n-particle reduced distribution functions
(n=0,......., N) generalizing the Gibbs fine-grained entropy formula.
Additionally, as a consequence of our microscopic analysis we find that this
nonequilibrium entropy behaves as a free entropic oscillator. In the approach
to the equilibrium regime we find relaxation equations of the Fokker-Planck
type, particularly for the one-particle distribution function
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