Hybrid choice model for propensity to travel and tour complexity

During the last years cities around the world have invested important quantities of money in measures for reducing congestion and car-trips. Investments which are nothing but potential solutions for the well-known urban sprawl phenomenon, also called the “development trap” that leads to further congestion and a higher proportion of our time spent in slow moving cars. Over the path of this searching for solutions, the complex relationship between urban environment and travel behaviour has been studied in a number of cases. The main question on discussion is, how to encourage multi-stop tours? Thus, the objective of this paper is to verify whether unobserved factors influence tour complexity. For this purpose, we use a data-base from a survey conducted in 2006-2007 in Madrid, a suitable case study for analyzing urban sprawl due to new urban developments and substantial changes in mobility patterns in the last years. A total of 943 individuals were interviewed from 3 selected neighbourhoods (CBD, urban and suburban). We study the effect of unobserved factors on trip frequency. This paper present the estimation of an hybrid model where the latent variable is called propensity to travel and the discrete choice model is composed by 5 alternatives of tour type. The results show that characteristics of the neighbourhoods in Madrid are important to explain trip frequency. The influence of land use variables on trip generation is clear and in particular the presence of commercial retails. Through estimation of elasticities and forecasting we determine to what extent land-use policy measures modify travel demand. Comparing aggregate elasticities with percentage variations, it can be seen that percentage variations could lead to inconsistent results. The result shows that hybrid models better explain travel behavior than traditional discrete choice models

Sliderule-like property of Wigner's little groups and cyclic S-matrices for multilayer optics

It is noted that two-by-two S-matrices in multilayer optics can be represented by the Sp(2) group whose algebraic property is the same as the group of Lorentz transformations applicable to two space-like and one time-like dimensions. It is noted also that Wigner's little groups have a sliderule-like property which allows us to perform multiplications by additions. It is shown that these two mathematical properties lead to a cyclic representation of the S-matrix for multilayer optics, as in the case of ABCD matrices for laser cavities. It is therefore possible to write the N-layer S-matrix as a multiplication of the N single-layer S-matrices resulting in the same mathematical expression with one of the parameters multiplied by N. In addition, it is noted, as in the case of lens optics, multilayer optics can serve as an analogue computer for the contraction of Wigner's little groups for internal space-time symmetries of relativistic particles.Comment: RevTex 13 pages, Secs. IV and V revised and expande

Using a regulator for a servomotor model designed for a prosthetic joint

Through the modern control theory it is possible to face any problem situation using state equations without considering mathematical rules used from recursive algorithms. The simplification of the various developments will be reflected with new findings, giving values to new concepts such as controllability and stability. This paper seeks to find new work items of the servomotor system by using a regulator, allowing a more controllable and stable performance. The servomotor presented here is designed to generate joint movements of a robotic arm designed for movement rehabilitation of a patient.V Workshop Procesamiento de Señales y Sistemas de Tiempo RealRed de Universidades con Carreras de Informática (RedUNCI

Fresnel coefficients as hyperbolic rotations

We describe the action of a plane interface between two semi-infinite media in terms of a transfer matrix. We find a remarkably simple factorization of this matrix, which enables us to express the Fresnel coefficients as a hyperbolic rotation.Comment: 6 pages, 3 figure

Derecho y tecnología médica: orígenes de su legislación en Argentina

La evaluación de tecnología sanitaria, la difusión de las innovaciones y su transferencia, los factores que conllevan a una rápida aceptación de las mismas y el rol que cumple la tecnología en la sociedad delimitan el campo de los fenómenos ciencia, técnica y salud. Su reconocimiento en los sistemas jurídicos a través de la instauración de un proceso para la incorporación de las mismas dentro de las esferas del Estado, más precisamente, en sus sistemas sanitarios, cuenta con cuatro etapas, a saber, a) planificación, b) evaluación, c) adquisición y, d) gestión. En este trabajo, desarrollamos los orígenes del segundo y tercer proceso, lo que en doctrina internacional y las prácticas de los gobiernos se denomina “evaluación de tecnologías sanitarias e incorporación” de éstas a los sistemas de salud, ya que consideramos que estudiar estos fenómenos desde su perspectiva histórica y legal, coadyuvaría a un mejor desempeño de nuestros Estados en pos del bienestar general y las inversiones que se realicen al respecto, determinando qué órgano es el competente para realizarlo

Optimizing omnidirectional reflection by multilayer mirrors

Periodic layered media can reflect strongly for all incident angles and polarizations in a given frequency range. Quarter-wave stacks at normal incidence are commonplace in the design of such omnidirectional reflectors. We discuss alternative design criteria to optimize these systems.Comment: 9 pages, 6 figures. To be published in J. Opt. A: Pure and Applied Optic

Iwasawa Effects in Multi-layer Optics

There are many two-by-two matrices in layer optics. It is shown that they can be formulated in terms of a three-parameter group whose algebraic property is the same as the group of Lorentz transformations in a space with two space-like and one time-like dimensions, or the $Sp(2)$ group which is a standard theoretical tool in optics. Among the interesting mathematical properties of this group, the Iwasawa decomposition drastically simplifies the matrix algebra under certain conditions, and leads to a concise expression for the S-matrix for transmitted and reflected rays. It is shown that the Iwasawa effect can be observed in multi-layer optics, and a sample calculation of the S-matrix is given.Comment: RevTex 10 pages including 1 psfi

In situ generation of COx-free H2 by catalytic ammonia decomposition over Ru-Al-monoliths

Ru catalysts supported on alumina coated monoliths has been prepared employing three different precursor, which are ruthenium chloride, ruthenium nitrosyl nitrate and ruthenium acetyl acetonate, by an equilibrium adsorption method. The Ru particle sizes could be controlled varying the metal precursor salt. Among the prepared catalysts, Ru catalyst prepared from nytrosyl nitrate exhibited the highest activity which is concomitant to the largest mean Ru particle size of 3.5 nm. The values of the apparent activation energy calculated from the Arrhenius equation are according to the Temkin-Phyzev model, indicating that the recombinative desorption of N ad-atoms is the rate-determining step of the reaction. However, the ratio between the kinetic orders with respect to ammonia and hydrogen (-a/ß), is not in agreement to the valued predict by Temkin formalism. This fact could be related to the different operational conditions used during the reaction, and/or catalyst nature, but not to any change on the controlling step of the reaction

Using a regulator for a servomotor model designed for a prosthetic joint

Through the modern control theory it is possible to face any problem situation using state equations without considering mathematical rules used from recursive algorithms. The simplification of the various developments will be reflected with new findings, giving values to new concepts such as controllability and stability. This paper seeks to find new work items of the servomotor system by using a regulator, allowing a more controllable and stable performance. The servomotor presented here is designed to generate joint movements of a robotic arm designed for movement rehabilitation of a patient.V Workshop Procesamiento de Señales y Sistemas de Tiempo RealRed de Universidades con Carreras de Informática (RedUNCI