From M-ary Query to Bit Query: a new strategy for efficient large-scale RFID identification

The tag collision avoidance has been viewed as one of the most important research problems in RFID communications and bit tracking technology has been widely embedded in query tree (QT) based algorithms to tackle such challenge. Existing solutions show further opportunity to greatly improve the reading performance because collision queries and empty queries are not fully explored. In this paper, a bit query (BQ) strategy based Mary query tree protocol (BQMT) is presented, which can not only eliminate idle queries but also separate collided tags into many small subsets and make full use of the collided bits. To further optimize the reading performance, a modified dual prefixes matching (MDPM) mechanism is presented to allow multiple tags to respond in the same slot and thus significantly reduce the number of queries. Theoretical analysis and simulations are supplemented to validate the effectiveness of the proposed BQMT and MDPM, which outperform the existing QT-based algorithms. Also, the BQMT and MDPM can be combined to BQMDPM to improve the reading performance in system efficiency, total identification time, communication complexity and average energy cost

Reconstrucción tridimensional de la velocidad del viento solar mediante tomografía Lyman-α

La determinación de la estructura termodinámica tridimensional (3D) de la corona solar por medios observacionales es de gran importancia para avanzar en la comprensión de los mecanismos físicos responsables del calentamiento coronal, así como para el desarrollo de modelos magnetohidrodinámicos (MHD) globales de la corona. Orientada a este fin, la tomografia solar rotacional utiliza series temporales de imágenes de la corona solar en luz visible (LV) y extremo ultravioleta, para determinar la distribución 3D de la densidad y temperatura electrónica de la corona solar. En este trabajo presentamos una nueva técnica tomográfica que, basada en imágenes coronales en Lyman-α y LV, permite la reconstrucción 3D del factor de atenuación Doppler Lyman-α. Este resultado, en combinación con un modelo global del campo magnético, permite reconstruir la distribución 3D de la velocidad del viento solar. El coronógrafo Metis a bordo de la misión espacial Solar Orbiter, que recientemente entró en operación, toma imágenes en ambos rangos espectrales, lo que permitirá aplicar la técnica por primera vez. Presentamos la metodología y resultados preliminares basados en simulaciones numéricas.Determination of the three-dimensional (3D) thermodynamic structure of the solar corona by observational means is of great importance to advance the understanding of the physical mechanisms responsible for coronal heating, as well as for the development of global magnetohydrodynamic (MHD) models of the corona. Oriented to this end, solar rotational tomography makes use of time series of images of the solar corona in visible light (VL) and in extreme ultraviolet, to determine the 3D distribution of the electron density and temperature of the solar corona. In this work we present a new tomographic technique that, based on coronal images in Lyman-α and VL, allows 3D reconstruction of the Lyman-α Doppler dimming term. In combination with a global model of the magnetic field, this allows 3D reconstruction of the solar wind speed. The recently operational Metis coronagraph, aboard the Solar Orbiter space mission, takes images in both spectral ranges, which will allow to apply the technique for the first time. We describe the methodology and present preliminary results based on numerical simulations.Asociación Argentina de Astronomí