Microwave invisibility cloaks based on frequency selective surfaces

En este proyecto se pretende comprender los fundamentos del funcionamiento de las capas de invisibilidad basadas en superficies selectivas en frecuencia (FSS) en microondas y realizar un diseño que pueda implementarse en la práctica con materiales de bajo coste. Se estudiará la teoría y se realizarán simulaciones de capas de invisibilidad ("invisibility cloacks") realizadas con FSS. Se realizará un diseño con materiales de bajo coste. Para las simulaciones se utilizará software comercial de electromagnetismo computacional.In this report the successful design, manufacturing and testing of Mantle Cloaking is presented. This relatively new technique goes beyond traditional metamaterial-based alternatives in the search for effective invisibility at the microwave range. In lieu thereof, Scattering Cancellation consists in optimizing the main coefficient affecting the scattered field with the aim of making it as low as possible. To do that at a certain frequency, the surface impedance of the cloak that provides this minimum value has to be calculated and properly manufactured. Since the cell surface impedance of Frequency Selective Surfaces can be mathematically characterized, this work will focus on the verification of every outcome and the computation of the impedance of the entire cloak from the point of view of simulation. Once this is confirmed, real measurements have determined the degree of reliability of the method and the accuracy of the results

Comparison Between Supervised and Unsupervised Classifications of Neuronal Cell Types: A Case Study

In the study of neural circuits, it becomes essential to discern the different neuronal cell types that build the circuit. Traditionally, neuronal cell types have been classified using qualitative descriptors. More recently, several attempts have been made to classify neurons quantitatively, using unsupervised clustering methods. While useful, these algorithms do not take advantage of previous information known to the investigator, which could improve the classification task. For neocortical GABAergic interneurons, the problem to discern among different cell types is particularly difficult and better methods are needed to perform objective classifications. Here we explore the use of supervised classification algorithms to classify neurons based on their morphological features, using a database of 128 pyramidal cells and 199 interneurons from mouse neocortex. To evaluate the performance of different algorithms we used, as a “benchmark,” the test to automatically distinguish between pyramidal cells and interneurons, defining “ground truth” by the presence or absence of an apical dendrite. We compared hierarchical clustering with a battery of different supervised classification algorithms, finding that supervised classifications outperformed hierarchical clustering. In addition, the selection of subsets of distinguishing features enhanced the classification accuracy for both sets of algorithms. The analysis of selected variables indicates that dendritic features were most useful to distinguish pyramidal cells from interneurons when compared with somatic and axonal morphological variables. We conclude that supervised classification algorithms are better matched to the general problem of distinguishing neuronal cell types when some information on these cell groups, in our case being pyramidal or interneuron, is known a priori. As a spin-off of this methodological study, we provide several methods to automatically distinguish neocortical pyramidal cells from interneurons, based on their morphologies

Structural properties of fluids interacting via piece-wise constant potentials with a hard core

The structural properties of fluids whose molecules interact via potentials with a hard core plus two piece-wise constant sections of different widths and heights are presented. These follow from the more general development previously introduced for potentials with a hard core plus $n$ piece-wise constant sections [Condens. Matter Phys. {\bf 15}, 23602 (2012)] in which use was made of a semi-analytic rational-function approximation method. The results of illustrative cases comprising eight different combinations of wells and shoulders are compared both with simulation data and with those that follow from the numerical solution of the Percus-Yevick and hypernetted-chain integral equations. It is found that the rational-function approximation generally predicts a more accurate radial distribution function than the Percus-Yevick theory and is comparable or even superior to the hypernetted-chain theory. This superiority over both integral equation theories is lost, however, at high densities, especially as the widths of the wells and/or the barriers increase.Comment: 10 pages, 11 figures; v2: Old Fig. 1 removed, new text on the correlation length, 7 new references added, plus other minor change

Fundamentos de los timers de los microcontroladores STM32F4

En este artículo se introducen los fundamentos de funcionamiento de los timers de la familia STM32F4 de microcontroladores ARM Cortex. Se enumeran los diferentes componentes y modos de funcionamiento y se explica, paso a paso, cómo utilizar las librerías CMSIS para configurarlos. Se suponen conocimientos básicos del sistema de relojes de esta familia de microcontroladores y de la utilización de las librerías CMSIS.Yuste Pérez, P. (2014). Fundamentos de los timers de los microcontroladores STM32F4. http://hdl.handle.net/10251/3953

Configuración de la frecuencia de trabajo de un microcontrolador STM32F4

En este artículo se introduce el sistema de relojes de la familia STM32F4 de los microcontroladores ARM Cortex. Se enumeran las fuentes de reloj que se pueden utilizar para generar el reloj del sistema y se explica, paso a paso, cómo hacer la configuración más habitual para conseguir la frecuencia deseada.Yuste Pérez, P. (2014). Configuración de la frecuencia de trabajo de un microcontrolador STM32F4. http://hdl.handle.net/10251/3953

Medición de tiempos con la familia de microcontroladores STM32

Utilización de los timers de microcontroladores STM32 en modo captura para medición de tiemposYuste Pérez, P. (2016). Medición de tiempos con la familia de microcontroladores STM32. http://hdl.handle.net/10251/68294DE

Lifetime of a target in the presence of N independent walkers

We study the survival probability of an immobile target in presence of N independent diffusing walkers. We address the problem of the Mean Target Lifetime and its dependence on the number and initial distribution of the walkers when the trapping is perfect or imperfect. We consider the diffusion on lattices and in the continuous space and we address the bulk limit corresponding to a density of diffusing particles and only one isolated trap. Also, we use intermittent motion for optimization of search strategies.Comment: 18 pages, 5 figures. Accepted for publication in Physica A

New insights into the expression and role of platelet FXIII-A

25 p.-6 fig.Background: The A subunit of factor XIII (FXIII-A) functions as an intracellular transglutaminase (TG) in the megakaryocyte/platelet lineage, where it probably participates in the cytoskeletal remodeling associated with cell activation. However, so far, the precise role of cellular FXIII (cFXIII) and the functional consequences of its absence in FXIII-A-deficient patients are unknown. Objectives and methods: In this study, we used platelets from four patients with congenital deficiency of FXIII-A to study the role of cFXIII in platelet functions. Results: We found that FXIII-A represents the only detectable source of TG activity in platelets and that the binding of fibrinogen in response to thrombin receptor agonist peptide (TRAP) stimulation was significantly reduced in platelets from the patients. In agreement with this, in control platelets, monodansyl-cadaverine (MDC), a competitive amino-donor for TGs, inhibited fibrinogen binding induced by TRAP in a dose-dependent manner. Moreover, upon adhesion to fibrinogen, normal platelets incubated with MDC as well as FXIII-A-deficient platelets showed a distinct extension pattern with reduced lamellipodia and increased filopodia formation, suggesting a delay in spreading. Conclusions: These findings provide evidence for the direct involvement of cFXIII-dependent TG activity in the regulation of platelet functionsThis work was supported by grants from the Dirección General de Investigación del Ministerio de Educación y Ciencia (BFU2006-00914) and Fundación Rodríguez Pascual. A. Jayo was recipient of a fellowship from the Ministerio de Educación y Ciencia. I. Conde holds a research contract from the Consejo Superior de Investigaciones Científica

Automatic deployment of an RPAS Mission Manager to an ARINC-653 compliant system

[EN] The development process of avionics system requiring a high level of safety is subjected to rigorous development and verification standards. In order to accelerate and facilitate this process, we present a testbed that uses a suite of methods and tools to comply with aerospace standards for certification. To illustrate the proposed methodology, we designed a Mission Management System for Remotely Piloted Aircraft Systems (RPAS) that was deployed on a particular run-time execution platform called XtratuM, an ARINC-653 compliant system developed in our research group. The paper discusses the system requirements, the software architecture, the key issues for porting designs to XtratuM, and how to automatize this process. Results show that the proposed testbed is a good platform for designing and qualifying avionics applications.This research has been financed by the Institute of Control Systems and Industrial Computing (Ai2), and by projects GVA AICO/2015/126 (Ayudas para Grupos de Investigacion Consolidables) and GVA ACIF/2016/197 (Ayudas para la contratacion de personal investigador en formacion de caracter predoctoral) of the Spanish Regional Government "Generalitat Valenciana".Usach Molina, H.; Vila Carbó, JA.; Crespo, A.; Yuste Pérez, P. (2018). Automatic deployment of an RPAS Mission Manager to an ARINC-653 compliant system. Journal of Intelligent & Robotic Systems. 92(3-4):587-598. https://doi.org/10.1007/s10846-017-0694-3S587598923-4Aeronautical Radio, Inc.: ARINC specification 653-1. Avionics Application Software Standard Interface (2003)Bonasso, R., Kerri, R., Jenks, K., Johnson, G.: Using the 3T architecture for tracking Shuttle RMS procedures. In: Proceedings of the IEEE International Joint Symposia on Intelligence and Systems. IEEE, Rockville, MD, USA (1998) https://doi.org/10.1109/IJSIS.1998.685440fentISS: XtratuM Hypervisor Emulator (SKE) start guide. Tech. rep., Universidad Politècnica de València (2015)Fons, B.: Plataforma para diseño y ejecución de aplicaciones de aviónica. Universitat Politècnica de València, Master’s thesis (2013)International Civil Aviation Organization: Doc. 9613 AN/937: Performance-based Navigation (PBN) Manual, 4th edn. (2013)International Civil Aviation Organization: Doc. 10019, AN/507: Manual on Remotely Piloted Aircraft Systems (RPAS), 1st edn. (2015)Koehl, D.: SESAR initiatives for RPAS integration. In: ICAO Remotely Piloted Aircraft Systems Symposium. Montreal, Canada (2015)Masmano, M., Ripoll, I., Crespo, A., Metge, J.: XtratuM: A hypervisor for safety critical embedded systems. In: Proceedings of the 11th Real-Time Linux Workshop. Dresden, Germany (2009)Masmano, M., Valiente, Y., Balbastre, P., Ripoll, I., Crespo, A., Metge, J.: LithOS: A ARINC-653 guest operating for XtratuM. In: Proceedings of the 12th Real-Time Linux Workshop. Nairobi, Kenia (2010)McCarley, J.S., Wickens, C.D.: Human factors implications of UAVs in the national airspace. Tech. Rep. AHFD-05-05/FAA-05-01, University of Illinois, Institute of Aviation, Aviation Human Factors Division (2005)North Atlantic Treaty Organization: STANAG 4703: Light Unmanned Aircraft Systems Airworthiness Requirements. NATO Standarization Agency (2014)Radio Technical Commission for Aeronautics (RTCA): DO-178C/ED-12C Software Considerations in Airborne Systems and Equipment Certification. RTCA (2011)Ribeiro, L.R., Oliveira, N.M.R.: UAV autopilot controllers test platform using Matlab/Simulink and X-Plane. In: 40th ASEE/ IEEE Frontiers in Education Conference. IEEE, Washington, DC, USA (2010). https://doi.org/10.1109/FIE.2010.5673378Spitzer, C.R.: Digital Avionics Handbook: Elements, Software and Functions, 2nd edn. CRC Press (2006)The MathWorks Inc.: Simulink Coder Target Language Compiler (2012)Usach, H.: Integridad y tolerancia a fallos en sistemas de aviónica. Universitat Politècnica de València, Master’s thesis (2014)Usach, H., Fons, B., Vila, J., Crespo, A.: An autopilot testbed for IMA (Integrated Modular Avionics) architectures. In: Proceedings of the 19th IFAC Symposium on Automatic Control in Aerospace. Elsevier, Würzburg, Germany (2013). https://doi.org/10.3182/20130902-5-DE-2040.00076Usach, H., Vila, J., Crespo, A., Yuste, P.: A highly-automated RPAS Mission Manager for integrated airspace. In: Proceedings of the 5th International Conference on Application and Theory of Automation in Command and Control Systems, ATACCS’15. ACM, Toulouse, France (2015). https://doi.org/10.1145/2899361.289936

Monoclinic polymorph of 2-(pyrimidin-2-ylsulfan­yl)acetic acid

The title compound, C6H6N2O2S, is a new polymorphic form of 2-(pyrimidin-2-ylsulfan­yl)acetic acid. Unlike the previous orthorhombic polymorph [Pan & Chen (2009 ▶) Acta Cryst. E65, o652], the mol­ecules are not planar: the aromatic ring makes an angle of 80.67 (17)° with the carboxyl plane. In the crystal, mol­ecules are linked by O—H⋯N hydrogen bonds into chains along [02]