NebulaStream: Complex Analytics Beyond the Cloud

The arising Internet of Things (IoT) will require significant changes to current stream processing engines (SPEs) to enable large-scale IoT applications. In this paper, we present challenges and opportunities for an IoT data management system to enable complex analytics beyond the cloud. As one of the most important upcoming IoT applications, we focus on the vision of a smart city. The goal of this paper is to bridge the gap between the requirements of upcoming IoT applications and the supported features of an IoT data management system. To this end, we outline how state-of-the-art SPEs have to change to exploit the new capabilities of the IoT and showcase how we tackle IoT challenges in our own system, NebulaStream. This paper lays the foundation for a new type of systems that leverages the IoT to enable large-scale applications over millions of IoT devices in highly dynamic and geo-distributed environments

Bringing big data into the car : does it scale?

PeerReviewe

Smart stream-based car information systems that scale : an experimental evaluation

PeerReviewe

Poster: Generating Reproducible Out-of-Order Data Streams

Evaluating modern stream processing systems in a reproducible manner requires data streams with different data distributions, data rates, and real-world characteristics such as delayed and out-of-order tuples. In this paper, we present an open source stream generator which generates reproducible and deterministic out-of-order streams based on real data files, simulating arbitrary fractions of out-of-order tuples and their respective delays.Web Information System

Thermodynamic correction of particle concentrations measured by underwing probes on fast-flying aircraft

Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular, for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable to different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain distance away from the aircraft. Conventional procedures for scaling the measured number densities to ambient conditions presume that the air volume probed per time interval is determined by the aircraft speed (true air speed, TAS). However, particle imaging instruments equipped with pitot tubes measuring the probe air speed (PAS) of each underwing probe reveal PAS values systematically below those of the TAS. We conclude that the deviation between PAS and TAS is mainly caused by the compression of the probed air sample. From measurements during two missions in 2014 with the German Gulfstream G-550 (HALO – High Altitude LOng range) research aircraft we develop a procedure to correct the measured particle concentration to ambient conditions using a thermodynamic approach. With the provided equation, the corresponding concentration correction factor ξ is applicable to the high-frequency measurements of the underwing probes, each of which is equipped with its own air speed sensor (e.g. a pitot tube). ξ values of 1 to 0.85 are calculated for air speeds (i.e. TAS) between 60 and 250 m s−1. For different instruments at individual wing position the calculated ξ values exhibit strong consistency, which allows for a parameterisation of ξ as a function of TAS for the current HALO underwing probe configuration. The ability of cloud particles to adopt changes of air speed between ambient and measurement conditions depends on the cloud particles' inertia as a function of particle size (diameter Dp). The suggested inertia correction factor μ (Dp) for liquid cloud drops ranges between 1 (for Dp < 70 µm) and 0.8 (for 100 µm < Dp < 225 µm) but it needs to be applied carefully with respect to the particles' phase and nature. The correction of measured concentration by both factors, ξ and μ (Dp), yields higher ambient particle concentration by about 10–25 % compared to conventional procedures – an improvement which can be considered as significant for many research applications. The calculated ξ values are specifically related to the considered HALO underwing probe arrangement and may differ for other aircraft. Moreover, suggested corrections may not cover all impacts originating from high flight velocities and from interferences between the instruments and e.g. the aircraft wings and/or fuselage. Consequently, it is important that PAS (as a function of TAS) is individually measured by each probe deployed underneath the wings of a fast-flying aircraft

Los efectos del cumplimiento de la condicio\u301n. Las rai\u301ces romanistas y el re\u301gimen en las codificaciones contempora\u301neas

El ensayo centra su atencio\u301n, desde una perspectiva comparativa sincro\u301nica y diacro\u301nica, en los efectos de la realizacio\u301n de la condicio\u301n, con particular referencia a los ordenamientos juri\u301dicos europeos y latinoamericanos. Algunos ordenamientos acogen, en esta materia, la regla de la retroactividad (eficacia ex tunc), mientras que otros hacen lo propio con la regla opuesta de la irretroactividad (eficacia ex nunc). esta duplicidad de orientaciones reconoce sus antecedentes ma\u301s remotos en el derecho romano. en efecto, la lectura de las fuentes induce a considerar que para los juristas romanos \u2013 guiados por el habitual pragmatismo, dirigido a adaptar las soluciones propuestas a las diferentes situaciones presentables o que se podri\u301an presentar \u2013 los efectos del negocio condicional a veces se producen ex nunc, otras, en cambio, ex tunc. Esta u\u301ltima solucio\u301n, reforzada por la autoridad de Bartolo, fue receptada por el Code Napole\u301on, mientras que la primera, mediante el ltro de la pandecti\u301stica, fue adoptada por el BgB. De ahi\u301 la duplicidad de soluciones, ambas atribuibles a la experiencia de la ciencia juri\u301dica romana