31 research outputs found
Modelos de programaci贸n estoc谩sticos para el dise帽o de redes log铆sticas
En la cadena de Abastecimiento, la gesti贸n log铆stica es la etapa de planifcaci贸n, en la cual, la distribuci贸n f铆sica de productos, programaci贸n y apoyo los procesos de fabricaci贸n, la planeaci贸n y las actividades se relacionan con los productos terminados y materiales determinados y organizados para obtener el mejor resultados. El problema de dise帽ar una red log铆stica, en muchos casos, se asocia a la formulaci贸n correcta del modelo en funci贸n del contexto, desde el desarrollo de los sistemas hasta la inclusi贸n de todas las posibles variables que pueden afectar los procesos. De todo esto, depende el 茅xito de su construcci贸n y los resultados veraces. Este trabajo muestra el dise帽o de una red log铆stica y la aplicaci贸n de restricciones estoc谩sticas en su programaci贸n, las variables aleatorias cambian todo el tiempo e incluso la variabilidad natural asociada a los procesos, esto con el fn de responder efectivamente la realidad de los sistemas dentro de las organizacionesAbstract: In a supply chain, logistical management is the planning stage, in which, the physical distribution of products, scheduling and supporting manufacturing operations, planning and activities are related with the fnal products and certain materials are organized for geting the wished results. The problem of designing a logistical network, in many cases, is associated to the correct formulation of the model according to the context in which, the systems develops; from the incursion of all the possible variables that can afect the processes, will depends the success of the said model and truthful results. This paper shows the design of a logistical network and the introduction of stochastic constrains in its programming, the random variables that change through the time with the natural variability associated to the processes, this with the purpose of responding more precisely to the reality inherent to the systems inside the organizations
Enhancement of Rabi Splitting in a Microcavity with an Embedded Superlattice
We have observed a large coupling between the excitonic and photonic modes of
an AlAs/AlGaAs microcavity filled with an 84-({\rm {\AA}})/20({\rm {\AA}})
GaAs/AlGaAs superlattice. Reflectivity measurements on the coupled
cavity-superlattice system in the presence of a moderate electric field yielded
a Rabi splitting of 9.5 meV at T = 238 K. This splitting is almost 50% larger
than that found in comparable microcavities with quantum wells placed at the
antinodes only. We explain the enhancement by the larger density of optical
absorbers in the superlattice, combined with the quasi-two-dimensional binding
energy of field-localized excitons.Comment: 5 pages, 4 figures, submitted to PR
Development of interference filters for porous silicon based photoluminescent devices
[ES] Las propiedades fotoluminiscentes y electroluminiscentes en el visible del silicio poroso hacen de 茅ste un material muy interesante para el
desarrollo de disposotivos optoelectr贸nicos. Para la obtenci贸n de dispositivos de calidad es necesario reducir la semianchura del espectro de
luminiscencia del silicio poroso, t铆picamente de unos 100 nm, para conseguir una emisi贸n monocrom谩tica. Esto puede conseguirse formando
sobre la capa luminiscente una estructura multicapa, tambi茅n de silicio poroso, que act煤e a modo de filtro interferencial. As铆 se consigue
estrechar el rango de emisi贸n cuanto se desee, sencillamente dise帽ando el filtro de manera conveniente. En este art铆culo se estudian las
propiedades 贸pticas de las capas de silicio poroso para el posterior dise帽o de estos filtros.[EN] Porous silicon鈥檚 photoluminescent and electroluminescent properties make it a very interesting material for the development of optoelectronic
devices. To obtain high quality devices it is mandatory to narrowen the porous silicon luminescent spectrum, tipically about 100 nm wide.
This can be obtained by forming a porous silicon multilayer structure on the luminescent layer that acts as an interference filter. Thus, the
emission spectrum can be narrowed as much as wished by simply designing the filter in the appropriate way. In this article, the optical
properties of porous silicon layers are studied for future filter design.Este trabajo ha sido financiado por el Ministerio de Ciencia
y Tecnolog铆a a trav茅s de la Comisi贸n Interministerial de Ciencia
y Tecnolog铆a, mediante el Proyecto de Investigaci贸n MAT2000-0375-
C02-01.Peer reviewe
Stochastic programming models for designing logistic networks
En la cadena de Abastecimiento, la gesti贸n log铆stica es la etapa de planificaci贸n, en la cual, la distribuci贸n f铆sica de
productos, programaci贸n y apoyo los procesos de fabricaci贸n, la planeaci贸n y las actividades se relacionan con los
productos terminados y materiales determinados y organizados para obtener el mejor resultados. El problema de
dise帽ar una red log铆stica, en muchos casos, se asocia a la formulaci贸n correcta del modelo en funci贸n del contexto,
desde el desarrollo de los sistemas hasta la inclusi贸n de todas las posibles variables que pueden afectar los procesos. De todo esto, depende el 茅xito de su construcci贸n y los resultados veraces. Este trabajo muestra el dise帽o de
una red log铆stica y la aplicaci贸n de restricciones estoc谩sticas en su programaci贸n, las variables aleatorias cambian
todo el tiempo e incluso la variabilidad natural asociada a los procesos, esto con el fin de responder efectivamente
la realidad de los sistemas dentro de las organizaciones.In a supply chain, logistical management is the planning stage, in which, the physical distribution of products,
scheduling and supporting manufacturing operations, planning and activities are related with the final products
and certain materials are organized for getting the wished results. The problem of designing a logistical network,
in many cases, is associated to the correct formulation of the model according to the context in which, the systems
develops; from the incursion of all the possible variables that can affect the processes, will depends the success
of the said model and truthful results. This paper shows the design of a logistical network and the introduction
of stochastic constrains in its programming, the random variables that change through the time with the natural
variability associated to the processes, this with the purpose of responding more precisely to the reality inherent
to the systems inside the organization
Depth-resolved microspectroscopy of porous silicon multilayers
3 pages, 3 figures.We have measured depth-resolved microphotoluminescence (PL) and micro-Raman spectra on the cross section of porous silicon multilayers to sample different layer depths. The PL emission band gets stronger, blueshifts, and narrows at the high porosity layers. On the contrary, the Raman band weakens and broadens. This band is fitted to the phonon confinement model. With the bulk silicon phonon frequency and its linewidth as free parameters, we obtain crystallite size, temperature, and stress as a function of depth. Sizes are larger than those estimated from PL. Laser power was reduced to eliminate heating effects. Compressive stresses in excess of 10 kbar are found in the deepest layer due to the lattice mismatch with the substrate.The authors acknowledge financial support from the
Spanish CICyT (Project Nos. MAT96-0395-CP and MAT97-
0725).Peer reviewe
Desarrollo de filtros interferenciales para emisores fotoluminiscentes basados en silicio poroso
Porous silicon鈥檚 photoluminescent and electroluminescent properties make it a very interesting material for the development of optoelectronic devices. To obtain high quality devices it is mandatory to narrowen the porous silicon luminescent spectrum, tipically about 100 nm wide. This can be obtained by forming a porous silicon multilayer structure on the luminescent layer that acts as an interference filter. Thus, the emission spectrum can be narrowed as much as wished by simply designing the filter in the appropriate way. In this article, the optical properties of porous silicon layers are studied for future filter design.<br><br>Las propiedades fotoluminiscentes y electroluminiscentes en el visible del silicio poroso hacen de 茅ste un material muy interesante para el desarrollo de disposotivos optoelectr贸nicos. Para la obtenci贸n de dispositivos de calidad es necesario reducir la semianchura del espectro de luminiscencia del silicio poroso, t铆picamente de unos 100 nm, para conseguir una emisi贸n monocrom谩tica. Esto puede conseguirse formando sobre la capa luminiscente una estructura multicapa, tambi茅n de silicio poroso, que act煤e a modo de filtro interferencial. As铆 se consigue estrechar el rango de emisi贸n cuanto se desee, sencillamente dise帽ando el filtro de manera conveniente. En este art铆culo se estudian las propiedades 贸pticas de las capas de silicio poroso para el posterior dise帽o de estos filtros
Generative policies for coalition systems - a symbolic learning framework
Policy systems are critical for managing missions and collaborative activities carried out by coalitions involving different organizations. Conventional policy-based management approaches are not suitable for next-generation coalitions that will involve not only humans, but also autonomous computing devices and systems. It is critical that those parties be able to generate and customize policies based on contexts and activities. This paper introduces a novel approach for the autonomic generation of policies by autonomous parties. The framework combines context free grammars, answer set programs, and inductionbased learning. It allows a party to generate its own policies, based on a grammar and some semantic constraints, by learning from examples. The paper also outlines initial experiments in the use of such a symbolic approach and outlines relevant research challenges, ranging from explainability to quality assessment of policies
Dispositivos aut贸matas para navegaci贸n, detecci贸n Recoleccion de pelotas de tenis en ambientes conocidos
En este art铆culo se muestran los rasgos principales de los robots TEL脡MACO y WALKER I. Estos aut贸matas tienen como fin desplazarse en un laberinto conocido, recolectar dos pelotas de tenis en su recorrido y depositarlas en un compartimiento ubicado a la salida de dicho laberinto, ejecutando dichas tareas lo m谩s r谩pido posible. Tambi茅n se describen las generalidades de la configuraci贸n de la estructura mec谩nica, del sistema sensorial, de las rutinas de programaci贸n y los esquemas circuitales
Dispositivos aut贸matas para navegaci贸n, detecci贸n Recoleccion de pelotas de tenis en ambientes conocidos
En este art铆culo se muestran los rasgos principales de los robots TEL脡MACO y WALKER I. Estos aut贸matas tienen como fin desplazarse en un laberinto conocido, recolectar dos pelotas de tenis en su recorrido y depositarlas en un compartimiento ubicado a la salida de dicho laberinto, ejecutando dichas tareas lo m谩s r谩pido posible. Tambi茅n se describen las generalidades de la configuraci贸n de la estructura mec谩nica, del sistema sensorial, de las rutinas de programaci贸n y los esquemas circuitales