Work and energy in inertial and non inertial reference frames

It is usual in introductory courses of mechanics to develop the work and energy formalism from Newton's laws. On the other hand, literature analyzes the way in which forces transform under a change of reference frame. Notwithstanding, no analogous study is done for the way in which work and energy transform under those changes of reference frames. We analyze the behavior of energy and work under such transformations and show explicitly the expected invariance of the formalism under Galilean transformations for one particle and a system of particles. The case of non inertial systems is also analyzed and the fictitious works are characterized. In particular, we show that the total fictitious work in the center of mass system vanishes even if the center of mass defines a non inertial frame. Finally, some subtleties that arise from the formalism are illustrated by examples.Comment: 4 pages, 2 figures. LaTeX2e. Part of the approach has been changed but results are unaltered. Version to appear im American Journal of Physic

Separation medium containing thermally exfoliated graphite oxide

A separation medium, such as a chromatography filling or packing, containing a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m.sup.2/g to 2600 m.sup.2/g, wherein the thermally exfoliated graphite oxide has a surface that has been at least partially functionalized

Periodic skyrmionic textures via conformal cartographic projections

We find periodic skyrmionic textures via conformal cartographic projections that map either an entire spherical parameter space or a hemisphere onto every regular polygon that provides regular tessellations of the plane. These maps preserve the sign of the Skyrme density throughout the entire space. We implement these textures in the polarization state of a laser beam, and demonstrate that paraxial fields where a periodic texture preserving the sign of the Skyrme density is implemented in the polarization state distribution unavoidably exhibit zeros

Electrostatic internal energy using the method of images

For several configurations of charges in the presence of conductors, the method of images permits us to obtain some observables associated with such a configuration by replacing the conductors with some image charges. However, simple inspection shows that the potential energy associated with both systems does not coincide. Nevertheless, it can be shown that for a system of a grounded or neutral conductor and a distribution of charges outside, the external potential energy associated with the real charge distribution embedded in the field generated by the set of image charges is twice the value of the internal potential energy associated with the original system. This assertion is valid for any size and shape of the conductor, and regardless of the configuration of images required. In addition, even in the case in which the conductor is not grounded nor neutral, it is still possible to calculate the internal potential energy of the original configuration through the method of images. These results show that the method of images could also be useful for calculations of the internal potential energy of the original system.Comment: 5 pages, 3 figures. New discussions added. Minor change

Bridged graphite oxide materials

Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media

Strain balanced quantum posts

Quantum posts are assembled by epitaxial growth of closely spaced quantum dot layers, modulating the composition of a semiconductor alloy, typically InGaAs. In contrast with most self-assembled nanostructures, the height of quantum posts can be controlled with nanometer precision, up to a maximum value limited by the accumulated stress due to the lattice mismatch. Here we present a strain compensation technique based on the controlled incorporation of phosphorous, which substantially increases the maximum attainable quantum post height. The luminescence from the resulting nanostructures presents giant linear polarization anisotropy.Comment: Submitted to Applied Physics Letters (7th March 2011). 4 pages, 4 figure

Work and energy in rotating systems

Literature analyzes the way in which Newton's second law can be used when non-inertial rotating systems are used. However, the treatment of the work and energy theorem in rotating systems is not considered in textbooks. In this paper, we show that the work and energy theorem can still be applied to a closed system of particles in a rotating system, as long as the work of fictitious forces is properly included in the formalism. The coriolis force does not contribute to the work coming from fictitious forces. It worths remarking that real forces that do not do work in an inertial reference frame can do work in the rotating reference frame and viceversa. The combined effects of acceleration of the origin and rotation of the non-inertial system are also studied.Comment: 6 pages, 3 figures, LaTeX2

Using Multi-granular Fuzzy Linguistic Modelling Methods to Represent Social Networks Related Information in an Organized Way

Social networks are the preferred mean for experts to share their knowledge and provide information. Therefore, it is one of the best sources that can be used for obtaining data that can be used for a high amount of purposes. For instance, determining social needs, identifying problems, getting opinions about certain topics, ... Nevertheless, this kind of information is difficult for a computational system to interpret due to the fact that the text is presented in free form and that the information that represents is imprecise. In this paper, a novel method for extracting information from social networks and represent it in a fuzzy ontology is presented. Sentiment analysis procedures are used in order to extract information from free text. Moreover, multi-granular fuzzy linguistic modelling methods are used for converting the information into the most suitable representation mean.This work has been supported by the ’Juan de la Cierva Incorporación’ grant from the Spanish Ministry of Economy and Competitiveness and by the Grant from the FEDER funds provided by the Spanish Ministry of Economy and Competitiveness (No. TIN2016-75850-R)

Diseño de un programa por computador para calcular los costos de la mecanización agrícola por cinco (5) métodos sicma

Empleando la metodología descrita por Towsend (1985), la cual considera cuatro (4) etapas: análisis, diseño, programación y validación, se elaboró un programa computarizado que permite calcular los costos por hora de la mecanización agrícola por los siguientes métodos: depreciación por línea recta (Valencia y González, 1973), método modificado de depreciación por línea recta (Reyes, 1985), depreciación por suma de dígitos (Álvarez, 1985), depreciación por suma de dígitos (Basto, 1985) y depreciación por el sistema de saldo decreciente (Bowers, 1977). Para estructurar el sistema, se definieron los datos de entrada, la información de salida tanto de carácter numérico como alfanumérico, así como las respectivas variables de acuerdo con la caracterización de cada uno de los métodos de cálculo de costos. Se establecieron los subsistemas o módulos respectivos, los cuales se determinaron para cada método y se definieron las relaciones posibles entre los subsistemas con el fin de compartir información. La fase de programación se llevó a cabo utilizando el lenguaje FOX PRO LAN, se crearon las respectivas bases de datos y se ejecutaron las diferentes rutinas con el fin de obtener los informes respectivos, los cuales se confrontaron con los resultados procesados manualmente. Los resultados del presente trabajo corresponden a las salidas impresas obtenidas para cada uno de los métodos de cálculo de costos.A computer program based on the methodology described by Towsend (1985) was designed. Such methodology considers four (4) steps: Analysis, design, programming, and validation. The program allows to estimate costs per hour in farm mechanization through the following methods: 1. Depreciation in straight line (Valencia y Gonzalez, 1973). 2. Modified method of depreciation in straight line (Reyes, 1985). 3. Depreciation by digits addition (Alvarez, 1985).  4.Depreciation by digits addition (Basto, 1985).  5.Depreciation by the balance-decreasing system (Bowers, 1977). Alfa numerical and numerical input and output data with its variables, according to characterization in each one of the cost calculating methods were defined in order to comform the information system. Subsystems were defined, based on each method, establishing the possible relationships between the various systems with the purpose of sharing information. The information system was fed to the computer when the programming was carried out. Then, database was established, to obtain the different reports for comparing them with those processed by hand, Thus, modifications and adjustments permiting the proper working of the program were carried out

Study of the soils of the Ebro Valley. I. Provinces of Logroño and Navarra

Final technical reportThe study of the soils of the provinces of Navarra and Logroño, both of which belong to the Ebro river basin, comprises two essential parts: on. the one hand, the mapping of the soils of the above mentioned provinces and, on the other, the preparation of the corresponding explicative report.The research reported in this document has been made possible through the support and sponsorship of the U.S. Department of the Army through its European Research Office. Contract No. DA-91-591-EUC-1085 1st. March 1959 to 30th February 1960.N