Phenotypic evolution in a venerid bivalve species lineage from the late Middle Miocene Central Paratethys Sea: a multi-approach morphometric analysis

A morphometric analysis was performed for the late Middle Miocene bivalve species lineage of Polititapes tricuspis (Eichwald, 1829) (Veneridae: Tapetini). Specimens from various localities grouped into two stratigraphically successive biozones, i.e. the upper Ervilia Zone and the Sarmatimactra Zone, were investigated using a multi-method approach. A Generalized Procrustes Analysis was computed for fifteen landmarks, covering characteristics of the hinge, muscle scars, and pallial line. The shell outline was separately quantified by applying the Fast Fourier Transform, which redraws the outline by fitting in a combination of trigonometric curves. Shell size was calculated as centroid size from the landmark configuration. Shell thickness, as not covered by either analysis, was additionally measured at the centroid. The analyses showed significant phenotypic differentiation between specimens from the two biozones. The bivalves become distinctly larger and thicker over geological time and develop circular shells with stronger cardinal teeth and a deeper pallial sinus. Data on the paleoenvironmental changes in the late Middle Miocene Central Paratethys Sea suggest the phenotypic shifts to be functional adaptations. The typical habitats for Polititapes changed to extensive, very shallow shores exposed to high wave action and tidal activity. Caused by the growing need for higher mechanical stability, the bivalves produced larger and thicker shells with stronger cardinal teeth. The latter are additionally shifted towards the hinge center to compensate for the lacking lateral teeth and improve stability. The deepening pallial sinus is related to a deeper burrowing habit, which is considered to impede being washed out in the new high-energy settings.

Neighborhood-corrected interface discontinuity factors for multi-group pin-by-pin diffusion calculations for LWR

Performing three-dimensional pin-by-pin full core calculations based on an improved solution of the multi-group diffusion equation is an affordable option nowadays to compute accurate local safety parameters for light water reactors. Since a transport approximation is solved, appropriate correction factors, such as interface discontinuity factors, are required to nearly reproduce the fully heterogeneous transport solution. Calculating exact pin-by-pin discontinuity factors requires the knowledge of the heterogeneous neutron flux distribution, which depends on the boundary conditions of the pin-cell as well as the local variables along the nuclear reactor operation. As a consequence, it is impractical to compute them for each possible configuration; however, inaccurate correction factors are one major source of error in core analysis when using multi-group diffusion theory. An alternative to generate accurate pin-by-pin interface discontinuity factors is to build a functional-fitting that allows incorporating the environment dependence in the computed values. This paper suggests a methodology to consider the neighborhood effect based on the Analytic Coarse-Mesh Finite Difference method for the multi-group diffusion equation. It has been applied to both definitions of interface discontinuity factors, the one based on the Generalized Equivalence Theory and the one based on Black-Box Homogenization, and for different few energy groups structures. Conclusions are drawn over the optimal functional-fitting and demonstrative results are obtained with the multi-group pin-by-pin diffusion code COBAYA3 for representative PWR configurations.

On-the-fly dynamic reprogramming mechanism for increasing the energy efficiency and supporting multi-experimental capabilities in WSNs

Remote reprogramming capabilities are one of the major concerns in WSN platforms due to the limitations and constraints that low power wireless nodes poses, especially when energy efficiency during the reprogramming process is a critical factor for extending the battery life of the devices. Moreover, WSNs are based on low-rate protocols in which as greater the amount of data is sent, the more the possibility to lose packets during the transmitting process is. In order to overcome these limitations, in this work a novel on-the-fly reprogramming technique for modifying and updating the application running on the wireless sensor nodes is designed and implemented, based on a partial reprogramming mechanism that significantly reduces the size of the files to be downloaded to the nodes, therefore diminishing their power/time consumption. This powerful mechanism also addresses multi-experimental capabilities because it provides the possibility to download, manage, test and debug multiple applications into the wireless nodes, based on a memory map segmentation of the core. Being an on-the-fly reprogramming process, no additional resources to store and download the configuration file are needed.

Conductivity variations of multi-walled carbon nanotubes oriented in liquid crystal cells

The control of carbon nanotubes conductivity is generating interest in several fields since it may be relevant for a number of applications. The self-organizing properties of liquid crystals may be used to impose alignment on dispersed carbon nanotubes,thus control-ling their conductivity and its anisotropy. This leads to a number of possible applications in photonic and electronic devices such as electrically controlled carbon nanotube switch- es and crossboards. In this work, cells of liquid crystals doped with multi-walled nanotubes have been prepared in different configurations. Their conductivity variations upon switching have been investigated. It turns out that conductivity evolution depends on the initial configuration (either homogeneous, homeotropic or in-plane switching), the cell thickness and the switching record. The control of these manufacturing paramenters allows the modulation of the electrical behavior of carbon nanotubes.

A 3D multi-objective optimization planning algorithm for wireless sensor networks

The complexity of planning a wireless sensor network is dependent on the aspects of optimization and on the application requirements. Even though Murphy's Law is applied everywhere in reality, a good planning algorithm will assist the designers to be aware of the short plates of their design and to improve them before the problems being exposed at the real deployment. A 3D multi-objective planning algorithm is proposed in this paper to provide solutions on the locations of nodes and their properties. It employs a developed ray-tracing scheme for sensing signal and radio propagation modelling. Therefore it is sensitive to the obstacles and makes the models of sensing coverage and link quality more practical compared with other heuristics that use ideal unit-disk models. The proposed algorithm aims at reaching an overall optimization on hardware cost, coverage, link quality and lifetime. Thus each of those metrics are modelled and normalized to compose a desirability function. Evolutionary algorithm is designed to efficiently tackle this NP-hard multi-objective optimization problem. The proposed algorithm is applicable for both indoor and outdoor 3D scenarios. Different parameters that affect the performance are analyzed through extensive experiments; two state-of-the-art algorithms are rebuilt and tested with the same configuration as that of the proposed algorithm. The results indicate that the proposed algorithm converges efficiently within 600 iterations and performs better than the compared heuristics.

Contribution to active multi-beam reconfigurable antennas for L and S bands

La presente tesis doctoral con título "Contribution to Active Multi-Beam Reconfigurable Antennas for L and S Bands" ha sido desarrollada por el investigador ingeniero de telecomunicación estudiante de doctorado Javier García-Gasco Trujillo en el Grupo de Radiación del Departamento de Señales, Sistemas y Radiocomunicaciones de la ETSI de Telecomunicación de la Universidad Politécnica de Madrid bajo la dirección de los doctores Manuel Sierra Pérez y José Manuel Fernández González. Durante décadas, el desarrollo de antenas de apuntamiento electrónico ha estado limitado al área militar. Su alto coste y su gran complejidad eran los mayores obstáculos que frenaban la introducción de esta tecnología en aplicaciones comerciales de gran escala. La reciente aparición de componentes de estado sólido prácticos, fiables, y de bajo coste ha roto la barrera del coste y ha reducido la complejidad, haciendo que las antenas reconfigurables de apuntamiento electrónico sean una opción viable en un futuro cercano. De esta manera, las antenas phased array podrían llegar a ser la joya de la corona que permitan alcanzar los futuros retos presentes en los sistemas de comunicaciones tanto civiles como militares. Así pues, ahora es el momento de investigar en el desarrollo de antenas de apuntamiento electrónico de bajo coste, donde los nuevos componentes de estado sólido comerciales forman el núcleo duro de la arquitectura. De esta forma, el estudio e implementación de estos arrays de antenas activas de apuntamiento electrónico capaces de controlar la fase y amplitud de las distintas señales implicadas es uno de los grandes retos de nuestro tiempo. Esta tesis se enfrenta a este desafío, proponiendo novedosas redes de apuntamiento electrónico e innovadores módulos de transmisión/recepción (T/R) utilizando componentes de estado sólido de bajo coste, que podrán integrar asequibles antenas activas reconfigurables multihaz en bandas L y S. En la primera parte de la tesis se realiza una descripción del estado del arte de las antenas phased array, incluyendo su base teórica y sus ventajas competitivas. Debido a que las contribuciones obtenidas en la presente tesis han sido realizadas dentro de distintos proyectos de investigación, donde se han manejada antenas de simple/doble polarización circular y simple/doble banda de trabajo, se describen detenidamente los dos proyectos más relevantes de la investigación: el radar de basura espacial de la Agencia Espacial Europea (ESA), Space Situational Awareness (SSA); y la estación base de seguimiento y control de satélites de órbita baja, GEOdesic Dome Array (GEODA). Sin lugar a dudas, los dispositivos desfasadores son uno de los componentes clave en el diseño de antenas phased arrays. Recientemente se ha observado una gran variación en el precio final de estos dispositivos, llegando en ocasiones a límites inasequibles. Así pues, se han propuesto distintas técnicas de conformación de haz alternativas a la utilización de componentes desfasadores comerciales: el desfasador de líneas conmutadas, la red de haz conmutado, y una novedosa red desfasadora divisora/combinadora de potencia. Para mostrar un uso práctico de las mismas, se ha propuesto el uso de las tres alternativas para el caso práctico del subarray de cinco elementos de la celda GEODA-SARAS. Tras dicho estudio se obtiene que la novedosa red desfasadora divisora/combinadora de potencia propuesta es la que mejor relación comportamiento/coste presenta. Para verificar su correcto funcionamiento se construye y mide los dos bloques principales de los que está compuesta la red total, comprobando que en efecto la red responde según lo esperado. La estructura más simple que permite realizar un barrido plano es el array triangular de tres elementos. Se ha realizado el diseño de una nueva red multihaz que es capaz de proporcionar tres haces ortogonales en un ángulo de elevación _0 y un haz adicional en la dirección broadside utilizando el mencionado array triangular de tres elementos como antena. En primer lugar se realizar una breve introducción al estado del arte de las redes clásicas multihaz. Así mismo se comentan innovadores diseños de redes multihaz sin pérdidas. El estudio da paso a las redes disipativas, de tal forma que se analiza su base matemática y se muestran distintas aplicaciones en arrays triangulares de tres elementos. Finalmente, la novedosa red básica propuesta se presenta, mostrando simulaciones y medidas de la misma para el caso prácticoo de GEODA. También se ha diseñado, construido y medido una red compuesta por dos redes básicas complementarias capaz de proporcionar seis haces cuasi-ortogonales en una dirección _0 con dos haces superpuestos en broadside. La red propuesta queda totalmente validada con la fabricación y medida de estos con prototipos. Las cadenas de RF de los módulos T/R de la nueva antena GEODA-SARAS no son algo trivial. Con el fin de mostrar el desarrollo de una cadena compleja con una gran densidad de componentes de estado sólido, se presenta una descripción detallada de los distintos componentes que integran las cadenas de RF tanto en transmisión como en recepción de la nueva antena GEODA-SARAS. Tras presentar las especificaciones de la antena GEODA-SARA y su diagrama de bloques esquemático se describen los dos bloques principales de las cadenas de RF: la celda de cinco elementos, y el módulo de conversión de panel. De la misma manera también se presentará el módulo de calibración integrado dentro de los dos bloques principales. Para comprobar que el funcionamiento esperado de la placa es el adecuado, se realizará un análisis que tratará entre otros datos: la potencia máxima en la entrada del transmisor (comprobando la saturación de la cadena), señal de recepción mínima y máxima (verificando el rango de sensibilidad requerido), y el factor G/T (cumpliendo la especificación necesaria). Así mismo se mostrará un breve estudio del efecto de la cuantificación de la fase en el conformado de haz de RF. Los estudios muestran que la composición de las cadenas de RF permite el cumplimiento de las especificaciones necesarias. Finalmente la tesis muestra las conclusiones globales del trabajo realizado y las líneas futuras a seguir para continuar con esta línea de investigación. ABSTRACT This PhD thesis named "Contribution to Active Multi-Beam Reconfigurable Antennas for L and S Bands", has been written by the Electrical Engineer MSc. researcher Javier García-Gasco Trujillo in the Grupo de Radiación of the Departamento de Señales, Sistemas y Radiocomunicaciones from the ETSI de Telecomunicación of the Universidad Politécnica de Madrid. For decades, the implementation of electronically steerable phased array antennas was confined to the military area. Their high cost and complexity were the major obstacles to introduce this technology in large scale commercial applications. The recent emergence of new practical, low-cost, and highly reliable solid state devices; breaks the barrier of cost and reduces the complexity, making active phased arrays a viable future option. Thus, phased array antennas could be the crown jewel that allow to meet the future challenges in military and civilian communication systems. Now is time to deploy low-cost phased array antennas, where newly commercial components form the core of the architecture. Therefore, the study and implementation of these novel low-cost and highly efficient solid state phased array blocks capable of controlling signal phase/amplitude accurately is one of the great challenges of our time. This thesis faces this challenge, proposing innovative electronic beam steering networks and transmitter/ receiver (T/R) modules using affordable solid state components, which could integrate fair reconfigurable phased array antennas working in L and S bands. In the first part of the thesis, a description of the state of art of phased array antennas, including their fundamentals and their competitive advantages, is presented. Since thesis contributions have been carried out for different research projects, where antennas with single/double circular polarization and single/double working frequency bands have been examined, frameworks of the two more important projects are detailed: the Space Situational Awareness (SSA) programme from the European Space Agency (ESA), and the GEOdesic Dome Array (GEODA) project from ISDEFE-INSA and the ESA. Undoubtedly, phase shifter devices are one of the key components of phased array antennas. Recent years have witnessed wide fluctuations in commercial phase shifter prices, which sometimes led to unaffordable limit. Several RF steering technique alternatives to the commercial phase shifters are proposed, summarized, and compared: the switched line phase shifter, the switched-beam network, and the novel phase shifter power splitter/combiner network. In order to show a practical use of the three different techniques, the five element GEODA-SARAS subarray is proposed as a real case of study. Finally, a practical study of a newly phase shifter power splitter/combiner network for a subarray of five radiating elements with triangular distribution is shown. Measurements of the two different phase shifter power splitter/combiner prototypes integrating the whole network are also depicted, demonstrating their proper performance. A triangular cell of three radiating elements is the simplest way to obtain a planar scanner. A new multibeam network configuration that provides three orthogonal beams in a desired _0 elevation angle and an extra one in the broadside steering direction for a triangular array of three radiating elements is introduced. Firstly, a short introduction to the state of art of classical multi-beam networks is presented. Lossless network analysis, including original lossless network designs, are also commented. General dissipative network theory as well as applications for array antennas of three radiating elements are depicted. The proposed final basic multi-beam network are simulated, built and measured to the GEODA cell practical case. A combined network that provides six orthogonal beams in a desired _0 elevation angle and a double seventh one in the broadside direction by using two complementary proposed basic networks will be shown. Measurements of the whole system will be also depicted, verifying the expected behavior. GEODA-SARAS T/R module RF chains are not a trivial design. A thorough description of all the components compounding GEODA-SARAS T/R module RF chains is presented. After presenting the general specifications of the GEODA-SARAS antenna and its block diagrams; two main blocks of the RF chains, the five element cell and the panel conversion module, are depicted and analyzed. Calibration module integrated within the two main blocks are also depicted. Signal flow throw the system analyzing critical situations such as maximum transmitted power (testing the chain unsaturation), minimum and maximum receiving signal (verifying sensitivity range), maximum receiver interference signals (assuring a proper reception), and G/T factor (fulfilling the technical specification) are evaluated. Phase quantization error effects are also listed. Finally, the manuscript contains the conclusions drawn of the present research and the future work.

Offline GA-Based optimization for heterogeneous modular multi-configurable chained microrobots

This paper presents a GA-based optimization procedure for bioinspired heterogeneous modular multiconfigurable chained microrobots. When constructing heterogeneous chained modular robots that are composed of several different drive modules, one must select the type and position of the modules that form the chain. One must also develop new locomotion gaits that combine the different drive modules. These are two new features of heterogeneous modular robots that they do not share with homogeneous modular robots. This paper presents an offline control system that allows the development of new configuration schemes and locomotion gaits for these heterogeneous modular multiconfigurable chained microrobots. The offline control system is based on a simulator that is specifically designed for chained modular robots and allows them to develop and learn new locomotion patterns.

Optimization and evaluation in space conditions of multi-GHz optical modulators

Among the different optical modulator technologies available such as polymer, III-V semiconductors, Silicon, the well-known Lithium Niobate (LN) offers the best trade-off in terms of performances, ease of use, and power handling capability [1-9]. The LN technology is still widely deployed within the current high data rate fibre optic communications networks. This technology is also the most mature and guarantees the reliability which is required for space applications [9].In or der to fulfil the target specifications of opto-microwave payloads, an optimization of the design of a Mach-Zehnder (MZ) modulator working at the 1500nm telecom wavelength was performed in the frame of the ESA-ARTES "Multi GigaHertz Optical Modulator" (MGOM) project in order to reach ultra-low optical insertion loss and low effective driving voltage in the Ka band. The selected modulator configuration was the X-cut crystal orientation, associated to high stability Titanium in-diffusion process for the optical waveguide. Starting from an initial modulator configuration exhibiting 9 V drive voltage @ 30 GHz, a complete redesign of the coplanar microwave electrodes was carried out in order to reach a 6 V drive voltage @ 30GHz version. This redesign was associated to an optimization of the interaction between the optical waveguide and the electrodes. Following the optimisation steps, an evaluation program was applied on a lot of 8 identical modulators. A full characterisation was carried out to compare performances, showing small variations between the initial and final functional characteristics. In parallel, two similar modulators were submitted to both gamma (10-100 krad) and proton irradiation (10.109 p/cm²) with minor performance degradation.

Cooperative Learning Model based on Multi-Agent Architecture for Embedded Intelligent Systems

Cooperative systems are suitable for many types of applications and nowadays these system are vastly used to improve a previously defined system or to coordinate multiple devices working together. This paper provides an alternative to improve the reliability of a previous intelligent identification system. The proposed approach implements a cooperative model based on multi-agent architecture. This new system is composed of several radar-based systems which identify a detected object and transmit its own partial result by implementing several agents and by using a wireless network to transfer data. The proposed topology is a centralized architecture where the coordinator device is in charge of providing the final identification result depending on the group behavior. In order to find the final outcome, three different mechanisms are introduced. The simplest one is based on majority voting whereas the others use two different weighting voting procedures, both providing the system with learning capabilities. Using an appropriate network configuration, the success rate can be improved from the initial 80% up to more than 90%.

Power-Aware Multi-Objective Evolvable Hardware System on an FPGA

Dynamic and Partial Reconfiguration (DPR) allows a system to be able to modify certain parts of itself during run-time. This feature gives rise to the capability of evolution: changing parts of the configuration according to the online evaluation of performance or other parameters. The evolution is achieved through a bio-inspired model in which the features of the system are identified as genes. The objective of the evolution may not be a single one; in this work, power consumption is taken into consideration, together with the quality of filtering, as the measure of performance, of a noisy image. Pareto optimality is applied to the evolutionary process, in order to find a representative set of optimal solutions as for performance and power consumption. The main contributions of this paper are: implementing an evolvable system on a low-power Spartan-6 FPGA included in a Wireless Sensor Network node and, by enabling the availability of a real measure of power consumption at run-time, achieving the capability of multi-objective evolution, that yields different optimal configurations, among which the selected one will depend on the relative “weights” of performance and power consumption.

Global Stability Analysis of a Compressible Turbulent Flow around a High-Lift Configuration

The purpose of this work is to analyze a complex high lift configuration for which significant regions of separated flow are present. Current state of the art methods have some diffculty to predict the origin and the progression of this separated flow when increasing the angle of attack. The mechanisms responsible for the maximum lift limit on multi-element wing con?gurations are not clear; this stability analysis could help to understand the physics behind the phenomenon and to find a relation between the flow separation and the instability onset. The methodology presented herein consists in the computation of a steady base flow solution based on a finite volume discretization and a proposal of the solution for a generalized eigenvalue problem corresponding to the perturbed and linearized problem. The eigenvalue problem has been solved with the Arnoldi iterative method, one of the Krylov subspace projection methods. The described methodology was applied to the NACA0012 test case in subsonic and in transonic conditions and, finally, for the first time to the authors knowledge, on an industrial multi-component geometry, such as the A310 airfoil, in order to identify low frequency instabilities related to the separation. One important conclusion is that for all the analyzed geometries, one unstable mode related to flow separation appears for an angle of attack greater than the one correspondent to the maximum lift coe?cient condition. Finally, an adjoint study was carried out in order to evaluate the receptivity and the structural sensitivity of the geometries, giving an indication of the domain region that could be modified resulting in the biggest change of the flowfield.

Multi-wavelength erbium/Raman gain based random distributed feedback fiber laser

A multiwavelength generation in a random distributed feedback fiber laser based on hybrid Raman and erbium gain and a Lyot all-fiber spectral filter is demonstrated for the first time. The use of erbium-doped fiber allows a multi-wavelength generation to be achieved at lower pump powers in comparison with random fiber lasers based on Raman gain only. The operating bandwidth and flatness of power distribution between different lines in generation are also improved in the hybrid gain configuration.

End-to-end versus hop-by-hop soft state refresh for multi-hop signalling systems

To ensure state synchronization of signalling operations, many signaling protocol designs choose to establish “soft” state that expires if it is not refreshed. The approaches of refreshing state in multi-hop signaling system can be classified as either end-to-end (E2E) or hop-by-hop (HbH). Although both state refresh approaches have been widely used in practical signaling protocols, the design tradeoffs between state synchronization and signaling cost have not yet been fully investigated. In this paper, we investigate this issue from the perspectives of state refresh and state removal. We propose simple but effective Markov chain models for both approaches and obtain closed-form solutions which depict the state refresh performance in terms of state consistency and refresh message rate, as well as the state removal performance in terms of state removal delay. Simulations verify the analytical models. It is observed that the HbH approach yields much better state synchronization at the cost of higher signaling cost than the E2E approach. While the state refresh performance can be improved by increasing the values of state refresh and timeout timers, the state removal delay increases largely for both E2E and HbH approaches. The analysis here shed lights on the design of signaling protocols and the configuration of the timers to adapt to changing network conditions.

Neural Approach in Multi-Agent Routing for Static Telecommunication Networks

The problem of multi-agent routing in static telecommunication networks with fixed configuration is considered. The problem is formulated in two ways: for centralized routing schema with the coordinator-agent (global routing) and for distributed routing schema with independent agents (local routing). For both schemas appropriate Hopfield neural networks (HNN) are constructed.

AdaptMCloud: uma estratégia para adaptação dinâmica de aplicações Multi-Cloud

Multi-Cloud Applications are composed of services offered by multiple cloud platforms where the user/developer has full knowledge of the use of such platforms. The use of multiple cloud platforms avoids the following problems: (i) vendor lock-in, which is dependency on the application of a certain cloud platform, which is prejudicial in the case of degradation or failure of platform services, or even price increasing on service usage; (ii) degradation or failure of the application due to fluctuations in quality of service (QoS) provided by some cloud platform, or even due to a failure of any service. In multi-cloud scenario is possible to change a service in failure or with QoS problems for an equivalent of another cloud platform. So that an application can adopt the perspective multi-cloud is necessary to create mechanisms that are able to select which cloud services/platforms should be used in accordance with the requirements determined by the programmer/user. In this context, the major challenges in terms of development of such applications include questions such as: (i) the choice of which underlying services and cloud computing platforms should be used based on the defined user requirements in terms of functionality and quality (ii) the need to continually monitor the dynamic information (such as response time, availability, price, availability), related to cloud services, in addition to the wide variety of services, and (iii) the need to adapt the application if QoS violations affect user defined requirements. This PhD thesis proposes an approach for dynamic adaptation of multi-cloud applications to be applied when a service is unavailable or when the requirements set by the user/developer point out that other available multi-cloud configuration meets more efficiently. Thus, this work proposes a strategy composed of two phases. The first phase consists of the application modeling, exploring the similarities representation capacity and variability proposals in the context of the paradigm of Software Product Lines (SPL). In this phase it is used an extended feature model to specify the cloud service configuration to be used by the application (similarities) and the different possible providers for each service (variability). Furthermore, the non-functional requirements associated with cloud services are specified by properties in this model by describing dynamic information about these services. The second phase consists of an autonomic process based on MAPE-K control loop, which is responsible for selecting, optimally, a multicloud configuration that meets the established requirements, and perform the adaptation. The adaptation strategy proposed is independent of the used programming technique for performing the adaptation. In this work we implement the adaptation strategy using various programming techniques such as aspect-oriented programming, context-oriented programming and components and services oriented programming. Based on the proposed steps, we tried to assess the following: (i) the process of modeling and the specification of non-functional requirements can ensure effective monitoring of user satisfaction; (ii) if the optimal selection process presents significant gains compared to sequential approach; and (iii) which techniques have the best trade-off when compared efforts to development/modularity and performance.