Optimal Design of Envelope Amplifier Based on Linear Assisted Buck Converter

Envelope Tracking (ET) and Envelope Elimination and Restoration (EER) are two techniques that have been used as a solution for highly efficient linear RF Power Amplifiers (PA). In both techniques the most important part is a dc-dc converter called envelope amplifier that has to supply the RF PA with variable voltage. Besides high efficiency, its bandwidth is very important as well. Envelope amplifier based on parallel combination of a switching dc-dc converter and a linear regulator is an architecture that is widely used due to its simplicity. In this paper we discuss about theoretical limitations of this architecture regarding its efficiency and we demonstrate two possible way of its implementation. In order to derive the presented conclusions, a theoretical model of envelope amplifier's efficiency has been presented. Additionally, the benefits of the new emerging GaN technology for this application have been shown as well.

Optimal design of AC EMI filters with damping networks and effect on the systems power factor

The cutoff frequencies of an EMI filter are normally given by the noise attenuation requirements the filter has to fulfill. In order to select the component values of the filter elements, i.e. inductances and capacitances, an additional design criterium is needed. In this paper the effect of the EMI filter input and output impedances are considered. The input impedance influences the filters effect on the system displacement power factor and the output impedance plays a key role in the system stability. The effect of filter element values, the number of filter stages as well as additional damping networks are considered and a design procedure is provided. For this analysis a two-port description of the input filters employing ABCD-parameters is used.

Dreams: A tool for the design of dynamically reconfigurable embedded and modular systems

Dynamically Reconfigurable Systems are attracting a growing interest, mainly due to the emergence of novel applications based on this technology. However, commercial tools do not provide enough flexibility to design solutions, while keeping an acceptable design productivity. In this paper, a novel design flow is proposed, targeting dynamically reconfigurable systems. It is fully supported by a tool called Dreams, which is able to implement flexible systems, starting from a set of netlists corresponding to the modules, as well as a system description provided by the user. The tool automatically post-processes the nets, implementing a solution for the communications between reconfigurable regions, as well as the handling of routing conflicts, by means of a custom router. Since the design process of every module and the static system are independent, the proposed flow is compatible with system upgrade at run-time. In this paper, a use case corresponding to the design of a highly regular and parallel mesh-type architecture is described, in order to show the architectural flexibility offered by the tool.

Analysis and optimized design of a distributed multi-stage EMC filter for an interleaved three-phase PWM-rectifier system for aircraft applications

Different possible input filter configurations for a modular three-phase PWM rectifier system consisting of three interleaved converter cells are studied. The system is designed for an aircraft application where MIL-STD-461E conducted EMI standards have to be met and system weight is a critical design issue. The importance of a LISN model on the simulated noise levels and the effect of interleaving and power unbalance between the different converter modules is discussed. The effect of the number of filter stages and the degree of distribution of the filter stages among the individual converter modules on the weight and losses of the input filter is studied and optimal filter structures are proposed.

Design of spherical symmetric gradient index lenses

Spherical symmetric refractive index distributions also known as Gradient Index lenses such as the Maxwell-Fish-Eye (MFE), the Luneburg or the Eaton lenses have always played an important role in Optics. The recent development of the technique called Transformation Optics has renewed the interest in these gradient index lenses. For instance, Perfect Imaging within the Wave Optics framework has recently been proved using the MFE distribution. We review here the design problem of these lenses, classify them in two groups (Luneburg moveable-limits and fixed-limits type), and establish a new design techniques for each type of problem.

On the design of spherical gradient index lenses

Classical spherical gradient index (GRIN) lenses (such as Maxwell Fish Eye lens, Eaton lens, Luneburg lens, etc.) design procedure using the Abel integral equation is reviewed and reorganized. Each lens is fully defined by a function called the angle of flight which describes the ray deflection through the lens. The radial refractive index distribution is obtained by applying a linear integral transformation to the angle of flight. The interest of this formulation is in the linearity of the integral transformation which allows us to derive new solutions from linear combinations of known lenses. Beside the review of the classical GRIN designs, we present a numerical method for GRIN lenses defined by the Abel integral equation with fixed limits, which is an ill-posed problem.

Design of a training tool for improving the use of hand-held detectors in humanitarian demining

Purpose – The purpose of this paper is to introduce the design of a training tool intended to improve deminers' technique during close-in detection tasks. Design/methodology/approach – Following an introduction that highlights the impact of mines and improvised explosive devices (IEDs), and the importance of training for enhancing the safety and the efficiency of the deminers, this paper considers the utilization of a sensory tracking system to study the skill of the hand-held detector expert operators. With the compiled information, some critical performance variables can be extracted, assessed, and quantified, so that they can be used afterwards as reference values for the training task. In a second stage, the sensory tracking system is used for analysing the trainee skills. The experimentation phase aims to test the effectiveness of the elements that compose the sensory system to track the hand-held detector during the training sessions. Findings – The proposed training tool will be able to evaluate the deminers' efficiency during the scanning tasks and will provide important information for improving their competences. Originality/value – This paper highlights the need of introducing emerging technologies for enhancing the current training techniques for deminers and proposes a sensory tracking system that can be successfully utilised for evaluating trainees' performance with hand-held detectors.

Zone design of specific sizes using adaptive additively weighted voronoi diagrams

Territory or zone design processes entail partitioning a geographic space, organized as a set of areal units, into different regions or zones according to a specific set of criteria that are dependent on the application context. In most cases, the aim is to create zones of approximately equal sizes (zones with equal numbers of inhabitants, same average sales, etc.). However, some of the new applications that have emerged, particularly in the context of sustainable development policies, are aimed at defining zones of a predetermined, though not necessarily similar, size. In addition, the zones should be built around a given set of seeds. This type of partitioning has not been sufficiently researched; therefore, there are no known approaches for automated zone delimitation. This study proposes a new method based on a discrete version of the adaptive additively weighted Voronoi diagram that makes it possible to partition a two-dimensional space into zones of specific sizes, taking both the position and the weight of each seed into account. The method consists of repeatedly solving a traditional additively weighted Voronoi diagram, so that each seed?s weight is updated at every iteration. The zones are geographically connected using a metric based on the shortest path. Tests conducted on the extensive farming system of three municipalities in Castile-La Mancha (Spain) have established that the proposed heuristic procedure is valid for solving this type of partitioning problem. Nevertheless, these tests confirmed that the given seed position determines the spatial configuration the method must solve and this may have a great impact on the resulting partition.

Assesing the usefulness of the ACM/IEEE-CS Computing Curricula for the design of Computer-Related Engineering Curricula, an experience in Telematics

This paper presents the rationale to build up a Telematics Engineering curriculum. Telematics is a strongly computing oriented area; then, the authors have initially intended to apply the common requirements described in the computing curricula elaborated by the ACM/EEEE-CS Joint Curriculum Task Force. This experience has revealed some problematic aspects in the ACM/IEEE-CS proposal. From the analysis of these problems, a model to guide the selection and specially the approach of the Telematics curriculum contents is proposed. This model can be easily generalized to other strongly computing oriented curricula, whose number is growing everyday

Functional and environmental design of detached, low crest level breakwaters

In this article we research the design of detached breakwaters, a type of coastal defence work designed to combat erosion on beaches in a stable, sustainable fashion. Our aim is to formulate a functional and environmental (nonstructural) method of design that defines the fundamental characteristics of a detached breakwater as a function of the desired effect on the coast whilst meeting social demands and preserving or improving the quality of the littoral environment. We aim to make this method generally applicable by considering relations between variables of different natures (climatic, geomorphologic, and geometric) influencing the changes experienced on the coast after the detached breakwater has been built. We carried out the study of the relations between the different variables on the data from 19 actual, existing detached breakwaters on the Spanish Mediterranean coastline, and we followed a methodology based on the implementation of nondimensional monomials and on a search for relations of dependency between them. Finally, we discussed the results obtained and came up with a proposal for a design method that uses some of the graphic relations found between the variables studied and that achieves the main objective. For example, a case of a detached breakwater’s geometric presizing is solved as a practical demonstration of how the method is applied. La investigación que se presenta en este artículo aborda el diseño de los diques exentos, por constituir estos un tipo de obras de defensa costera con el que poder luchar de una forma estable y sostenible contra muchos de los problemas de erosión que existen en las playas. El objetivo principal de este trabajo es la formulación de un método de diseño funcional y ambiental (no estructural) que permita definir las características fundamentales de un dique exento en función del efecto que se quiera inducir en la costa, satisfaciendo las demandas sociales y preservando o mejorando la calidad del medio ambiente litoral. Además, se busca la aplicabilidad general del método mediante la consideración de relaciones entre variables de distinta naturaleza (climáticas, geomorfológicas y geométricas) que tienen influencia en los cambios que se experimentan en la costa tras la construcción del dique exento. El estudio de las relaciones entre las distintas variables se realiza sobre los datos de una base de diecinueve diques exentos reales, existentes en el litoral mediterráneo español, y sigue una metodología basada en el planteamiento de monomios adimensionales y en la búsqueda de relaciones de dependencia entre ellos. Finalmente, la discusión de los resultados obtenidos conduce a la propuesta de un método de diseño que utiliza algunas de las relaciones graficas encontradas entre las variables estudiadas y con el que se consigue el objetivo principal anteriormente expuesto. Para demostrar la aplicación práctica del método se resuelve un caso de predimensionamiento geométrico de un dique exento a modo de ejemplo.

Uncertainties in the design of support structures and foundations for offshore wind turbines

Offshore wind industry has exponentially grown in the last years. Despite this growth, there are still many uncertainties in this field. This paper analyzes some current uncertainties in the offshore wind market, with the aim of going one step further in the development of this sector. To do this, some already identified uncertainties compromising offshore wind farm structural design have been identified and described in the paper. Examples of these identified uncertainties are the design of the transition piece and the difficulties for the soil properties characterization. Furthermore, this paper deals with other uncertainties not identified yet due to the limited experience in the sector. To do that, current and most used offshore wind standards and recommendations related to the design of foundation and support structures (IEC 61400-1, 2005; IEC 61400-3, 2009; DNV-OS-J101, Design of Offshore Wind Turbine, 2013 and Rules and Guidelines Germanischer Lloyd, WindEnergie, 2005) have been analyzed. These new identified uncertainties are related to the lifetime and return period, loads combination, scour phenomenon and its protection, Morison e Froude Krilov and diffraction regimes, wave theory, different scale and liquefaction. In fact, there are a lot of improvements to make in this field. Some of them are mentioned in this paper, but the future experience in the matter will make it possible to detect more issues to be solved and improved.

Conceptual design of the beryllium rotating target for the ESS-Bilbao facility

The ESS-Bilbao facility, hosted by the University of the Basque Country (UPV/EHU), envisages the operation of a high-current proton accelerator delivering beams with energies up to 50 MeV. The time-averaged proton current will be 2.25 mA, delivered by 1.5 ms proton pulses with a repetition rate of 20 Hz. This beam will feed a neutron source based upon the Be (p,n) reaction, which will enable the provision of relevant neutron experimentation capabilities. The neutron source baseline concept consists in a rotating beryllium target cooled by water. The target structure will comprise a rotatable disk made of 6061-T6 aluminium alloy holding 20 beryllium plates. Heat dissipation from the target relies upon a distribution of coolant-flow channels. The practical implementation of such a concept is here described with emphasis put on the beryllium plates thermo-mechanical optimization, the chosen coolant distribution system as well as the mechanical behavior of the assembly.

Design of an assessment methodology for Educational Innovation Groups in the EHEA.

This document explains the process of designing a methodology to evaluate Educational Innovation Groups, which are structures created within universities in the context of adaptation to the European Higher Education Area. These groups are committed to introduce innovation in educational processes as a means to improve educational quality. The assessment design is based on a participatory model of planning called Working With People, that tries to integrate the perspectives of all stakeholders. The aim of the methodology is to be a useful tool for the university to evaluate the work done by the groups, encourage the members to continue improving the quality of teaching and reorient the activities to fulfill the emergent needs that the university faces.

System Engineering Approach to Initial Design of LEO Remote Sensing Missions

The satellite remote sensing missions are essential for long-term research around the condition of the earth resources and environment. On the other hand, in recent years the application of microsatellites is of interest in many space programs for their less cost and response time. In microsatellite remote sensing missions there are tight interrelations between different requirements such as orbital altitude, revisit time, mission life and spatial resolution. Also, all of these requirements can affect the whole system level design characteristics. In this work, the remote sensing microsatellite sizing process is divided into three major design disciplines; a) orbit design, b) payload sizing and c) bus sizing. Finally, some specific design cases are investigated inside the design space for evaluating the effect of different design variables on the satellite total mass. Considering the results of the work, it is concluded that applying a systematic approach at the initial design phase of such projects provides a good insight to the not clearly seen interactions inside their highly extended design space

The role of land and water for trade and food production in Latin America: Environmental trade-offs of agricultural intensification versus extensification

One of humanity’s major challenges of the 21st century will be meeting future food demands on an increasingly resource constrained-planet. Global food production will have to rise by 70 percent between 2000 and 2050 to meet effective demand which poses major challenges to food production systems. Doing so without compromising environmental integrity is an even greater challenge. This study looks at the interdependencies between land and water resources, agricultural production and environmental outcomes in Latin America and the Caribbean (LAC), an area of growing importance in international agricultural markets. Special emphasis is given to the role of LAC’s agriculture for (a) global food security and (b) environmental sustainability. We use the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT)—a global dynamic partial equilibrium model of the agricultural sector—to run different future production scenarios, and agricultural trade regimes out to 2050, and assess changes in related environmental indicators. Results indicate that further trade liberalization is crucial for improving food security globally, but that it would also lead to more environmental pressures in some regions across Latin America. Contrasting land expansion versus more intensified agriculture shows that productivity improvements are generally superior to agricultural land expansion, from an economic and environmental point of view. Finally, our analysis shows that there are trade-offs between environmental and food security goals for all agricultural development paths.