Showing papers by "Technical University of Madrid published in 1985"
TL;DR: In this paper, a model for the collection of energy on both sides of a bifacial photovoltaic panel surrounded by white-painted planes which produce diffuse reflections of the energy reaching them is presented.
66 citations
TL;DR: In this paper, the authors describe several pulsewidth modulation (PWM) waveforms where a predetermined number of unwanted harmonics can be canceled, and the advantages and disadvantages of different methods of delaying the signals in small microprocessor controlled PWM inverter drive systems are considered.
Abstract: Microprocessor control of power electronic systems offers the possibility of improvements in reliability, maintenance and servicing, and increased control flexibility. This paper describes several pulsewidth modulation (PWM) waveforms where a predetermined number of unwanted harmonics can be canceled. The advantages and disadvantages of the different methods of delaying the signals in small microprocessor controlled PWM inverter drive systems are considered. Several examples of single-phase and three-phase PWM inverters, with the laws which govern the commutation angles, output waveforms, and their respective frequency spectra are presented.
15 citations
TL;DR: An artificial diet that has been used to rear 26 species of boring cerambycid beetles is described and has been useful in taxonomic and cytogenetic studies.
Abstract: An artificial diet that has been used to rear 26 species of boring cerambycid beetles is described. Development of the insects in the laboratory varied from partial to total completion of the life cycle. This method has been useful in taxonomic and cytogenetic studies.
14 citations
TL;DR: A package of connected code systems for the neutronic calculations relevant in fuel management and core design of pressurized water reactors (PWRs) has been developed and applied for validation to... as discussed by the authors.
Abstract: A package of connected code systems for the neutronic calculations relevant in fuel management and core design of pressurized water reactors (PWRs) has been developed and applied for validation to ...
11 citations
TL;DR: A new family of 2-D nonimaging concentrators is presented and the most significant characteristics are their small size and the fact that they use straight, as opposed to curved, reflective, or refractive interfaces.
Abstract: A new family of 2-D nonimaging concentrators is presented. The most significant characteristics of these concentrators are their small size and the fact that they use straight, as opposed to curved, reflective, or refractive interfaces. The concentrators are filled with a medium of refractive index n > 1 and use narrow strips of refractive index ns < n. These strips are transparent, or act as mirrors, depending on the angle of incidence of the rays. The direction of the collected rays (i.e., rays reaching the receiver) at they entry aperture can be varied by modifying the refractive indices of the strips.
11 citations
TL;DR: In this paper, the authors deal with the transient analysis of the catalytic ignition of premixed gases over a flat plate of finite thickness, where the ignition process is facilitated by an external heat flux added to the combustible gases through the plate.
Abstract: This paper deals with the transient analysis of the catalytic ignition of premixed gases over a flat plate of finite thickness. The ignition process is facilitated by an external heat flux added to the combustible gases through the plate. Activation energy asymptotic methods based on high Zeldovich numbers are used to deduce analytical expressions for the critical time for ignition. This ignition process can be characterized by three different stages: inert heating, transition, and diffusion-controlled completion. The influence of the finite thermal conductivity of the plate, which permits feedback of the heat on the transient ignition process, is also evaluated. 11 references.
7 citations
TL;DR: In this article, l'aide du modele parametrique de Chondury de la correlation entre le rayonnement solaire direct a incidence normal and le rayónnement global sur une surface horizontalale for un ciel serein and unciel ouvert.
6 citations
17 Jun 1985
5 citations
TL;DR: In this article, the authors apply linear elastic fracture mechanics to plain concrete, provided the fracture process zone is small compared with the size of the structural element and the stress State at the tip of the crack can be characterized by means of the stress intensity factor.
Abstract: Linear Elastic Fracture Mechanics can be applied to plain concrete provided the fracture process zone be small compared with the size of the structural element In this situation the stress State at the tip of the crack can be characterized by means of the stress intensity factor The first part of the paper considers modeling crack extension in concrete by the finite element method The second part deals with an example problem, the cracked Fontana Dam
4 citations
TL;DR: In this paper, a cohesive crack model is introduced and applied to derive a size effect law similar to Bazant's, and the theoretical basis of RILEM and BOW is analyzed.
Abstract: This contribution has two objectives: To introduce a non linear model for concrete fracture and to analyze test methods for measuring G F .
The apparent reason for the inapplicability in many cases of linear elastic fracture mechanics to cracking in concrete lies in the nature of the process zone. To overcome this difficulty a cohesive crack model is introduced and applied to derive a size effect law, similar to Bazant's.
Despite the overwhelming number of fracture experiments, there is still lack of knowledge about the basic parameter G F . This paper aims to analyze the theoretical basis of such methods as well as to discuss test results obtained by the authors according to RILEM and Bazant proposals.
4 citations
01 Apr 1985
TL;DR: This paper provides a first structured view of using the L1-norm minimization of error when computing the parameters corresponding to spectral estimation models, discussing its interest and advantage/disadvantage balance compared with the standard L2- norm minimization procedures.
Abstract: This paper provides a first structured view of using the L 1 -norm minimization of error when computing the parameters corresponding to spectral estimation models, discussing its interest and advantage/disadvantage balance compared with the standard L 2 -norm minimization procedures. Some examples illustrate this comparison.
01 Jan 1985
17 Jun 1985
TL;DR: The flora and fauna of ‘El Regajal’, an estate in the province of Madrid, are described, and the efforts so far made to protect them are enumerated.
17 Jun 1985
TL;DR: In this paper, the authors considered the case of a monopole placed along the axis of a circular disk and used the Equivalent Current Method (ECM) to solve the problem.
Abstract: Several authors have calculated the input impedance of monopoles on finite ground planes using hybrid MM/GTD techniques [1]-[4]. However, in the case of a circular disk, only monopoles placed along the axis of the disk have been considered. This axis is then a caustic of the diffracted rays and the Equivalent Current Method (ECM) must therefore be used to solve the problem. We deal here with the more general situation of a monopole located at any point on the disk and oriented in an arbitrary direction \theta_{m} , \phi_{m} (Fig.1). The purpose of this paper is to compute the input impedance of the monopole off the axial caustic using a hybrid MM/UTD technique and to investigate the validity of the solution when the monopole is close to the edge of the disk.
TL;DR: In this article, a-Si films were deposited by electron beam evaporation onto titanium-coated stainless steel substrates held at temperatures T s ranging between 300 and 800°C, and conductivities were measured as functions of the temperature in sandwich structures with aluminium contacts.
01 Apr 1985
TL;DR: A predictive approach for hierarchical line encoding is presented, giving rise to a two step procedure (hierarchical plus predictive), both predictor and quantiser have been adapted to the different pixel weight within the hierarchical code; the selective quantiser has so been developed as a function of code outgrowth layer.
Abstract: Properties related with statistical redundancy of hierarchical image codes have been unveiled recently, allowing for a potential high bit rate reduction in storage or transmission. Appropriate schemes can be developed to take advantage of these properties, either for lossless or lossy applications. Here, a predictive approach for hierarchical line encoding is presented, giving rise to a two step procedure (hierarchical plus predictive). Both predictor and quantiser have been adapted to the different pixel weight within the hierarchical code; the selective quantiser has so been developed as a function of code outgrowth layer. Zero bit quantisation is also used to reduce bit rate in the large uniform areas of last code layers. Performance of the proposed scheme has been tested on a significative set of images, behaving well even with high entropy pictures. Results offer encoding at a bit rate around 0.5 bit/pixel, while subjective quality is still kept high.
01 Jan 1985
TL;DR: In this article, the steady state catalytic ignition of premixed gases over a flat plate of finite thickness was evaluated in the two distinct limits of the reduced Damkohler number of order of unity and much less than unity.
Abstract: This paper deals with the steady state catalytic ignition of premixed gases over a flat plate of finite thickness. An external heat flux is added to the plate to facilitate the ignition process. The influence of the finite thermal conductivity of the plate on the catalytic ignition is evaluated in the two distinct limits of the reduced Damkohler number of order of unity and much less than unity. In the case of the reduced Damkohler number of order of unity, the chemical reaction is important over the whole length of the plate. The results obtained previously without external energy flux are reproduced. In the case of the reduced Damkohler number much less than unity, which is of practical interest, the chemical reaction is important only in a narrow zone close to the trailing edge, except for very high thermal conductivity of the plate. Analytical expressions are obtained for the critical external heat flux required to produce the catalytic ignition.
01 Jan 1985
01 Jan 1985
TL;DR: The response of the system to a non infinitely narrow transmitted pulse can be focused and an improved clinical image can be obtained using deconvolution techniques.
Abstract: The response of the system to a non infinitely narrow transmitted pulse can be focused and an improved clinical image can be obtained using deconvolution techniques. Several deconvolution methods are described to achieve image improvement in real time, using digital processing.
TL;DR: In this article, a simulation of the dynamic behavior of a robot of the SCARA family in a digital computer is presented, where the Lagrange method is used to obtain the mechanical model and the electrical model for the actuators and motors.
TL;DR: A new algorithm is proposed, that allows to carry out these calculations either in the continuous or discrete case, and has shown to have similar computer time consumption that the other, but with the advantage of being suitable for the design of discrete control systems.
TL;DR: In this paper, the dominant mechanism in the population distribution between n = 2 of Li and He levels is studied theoretically, taking into account both the rotational and radial couplings.
Abstract: The aim of this work is to study theoretically the dominant mechanism in the population distribution between n=2 of Li and He levels. To be able to account for the experimental findups, ‘ab-initio’ calculations have been performed. These calculations take into account both the rotational and radial couplings.
TL;DR: In this paper, a Taylor's series expansion of some inverse trigonometric functions is proposed to perform the cartesian to joint coordinates conversion in real-time for SCARA robots.
TL;DR: In this paper, a part positioning device for inspection of carbon fiber aeronautic parts has been developed for a PDP-11/234 host minicomputer, two IRb-6/2 or IRb60/2 ASEA's robots and CNC controled part positioning devices.