In the context of railway safety, it is crucial to know the positions of all trains moving along the infrastructure. In this contribution, we present an algorithm that extracts the positions of ...moving trains for a given point in time from Distributed Acoustic Sensing (DAS) signals. These signals are obtained by injecting light pulses into an optical fiber close to the railway tracks and measuring the Rayleigh backscatter. We show that the vibrations of moving objects can be identified and tracked in real-time yielding train positions every second. To speed up the algorithm, we describe how the calculations can partly be based on graphical processing units. The tracking quality is assessed by counting the inaccurate and lost train tracks for two different types of cable installations.
Major tunnel projects like the new Semmering Base Tunnel require intensive design work long before construction can start. Design work is based on basic surveying, which is subject to particular ...requirements on major projects of engineering geodesy. The most important basis is a homogeneous and stress‐free basic control network for position and height, represented by suitable stabilised points. The conception and implementation of this basic control network poses stringent requirements for the surveyor. On the one hand, great precision and reliability are required, and on the other hand design requirements have to be considered along with the numerous geodetic and geophysical considerations. The most challenging work, which has to be undertaken above ground for the later tunnelling works, is described in detail in this article
Große Tunnelbauvorhaben wie der neue Semmering Basistunnel erfordern bereits lange vor der Realisierung intensive Planungsarbeiten. Grundlage für alle Planungstätigkeiten sind Vermessungsgrundlagen, an die bei ingenieurgeodätischen Großprojekten besondere Anforderungen gestellt werden. Die wichtigste Basis ist ein homogenes und spannungsfreies Grundlagennetz in Lage und Höhe, das durch geeignet stabilisierte Punkte repräsentiert wird. Die Konzeption und Realisierung dieses Grundlagennetzes stellt hohe Anforderungen an den Vermessungsingenieur. Zum einen ist höchste Präzision und Zuverlässigkeit gefordert, zum anderen sind neben zahlreichen geodätischen und geophysikalischen Rahmenbedingungen auch Vorgaben aus der Projektierung zu berücksichtigen. Die herausfordernden Arbeiten, die bei der übertägigen Grundlagenvermessung für den späteren Tunnelvortrieb notwendig sind, werden in diesem Beitrag ausführlich dokumentiert.
SBTn basic surveying for tunnelling Macheiner, Klaus; Doller, Herbert; Jachs, Wilhelm ...
Geomechanik und Tunnelbau,
12/2013, Letnik:
6, Številka:
6
Journal Article
Recenzirano
Major tunnel projects like the new Semmering Base Tunnel require intensive design work long before construction can start. Design work is based on basic surveying, which is subject to particular ...requirements on major projects of engineering geodesy. The most important basis is a homogeneous and stress-free basic control network for position and height, represented by suitable stabilised points. The conception and implementation of this basic control network poses stringent requirements for the surveyor. On the one hand, great precision and reliability are required, and on the other hand design requirements have to be considered along with the numerous geodetic and geophysical considerations. The most challenging work, which has to be undertaken above ground for the later tunnelling works, is described in detail in this article.Original Abstract: Grose Tunnelbauvorhaben wie der neue Semmering Basistunnel erfordern bereits lange vor der Realisierung intensive Planungsarbeiten. Grundlage fuer alle Planungstaetigkeiten sind Vermessungsgrundlagen, an die bei ingenieurgeodaetischen Grosprojekten besondere Anforderungen gestellt werden. Die wichtigste Basis ist ein homogenes und spannungsfreies Grundlagennetz in Lage und Hohe, das durch geeignet stabilisierte Punkte repraesentiert wird. Die Konzeption und Realisierung dieses Grundlagennetzes stellt hohe Anforderungen an den Vermessungsingenieur. Zum einen ist hochste Praezision und Zuverlaessigkeit gefordert, zum anderen sind neben zahlreichen geodaetischen und geophysikalischen Rahmenbedingungen auch Vorgaben aus der Projektierung zu beruecksichtigen. Die herausfordernden Arbeiten, die bei der uebertaegigen Grundlagenvermessung fuer den spaeteren Tunnelvortrieb notwendig sind, werden in diesem Beitrag ausfuehrlich dokumentiert.
For traffic monitoring systems it is desirable to have a low-cost, low-maintenance, and reliable system to facilitate continuous and safe traffic flow. In line with this, we introduce distributed ...acoustic sensing (DAS) for traffic monitoring applications. In DAS systems, series of light pulses are transmitted along a fiber-optic cable and the back-scattered light, which is affected by the mechanical strain of the fiber-optic cables due to ground vibrations, is measured and analyzed. With fiber-optic cables installed parallel to a highway where ground vibrations are induced by passing vehicles, traffic information such as vehicle flow and average speeds can be estimated from the DAS signals. In this paper, we present an algorithm based on image processing methods that estimates traffic information from image representations generated from 1-minute segments of DAS signals. We tested the results of the algorithm on DAS data recording on a real highway against reference traffic data measured by road-side sensors.
The health care industry needs a database architecture that will allow the easy maintenance of a large evolving database. An object oriented inferencing database architecture modeled after ...physiological systems is proposed. The medical database, usually modeled with all fields as global variables, is in this model partitioned into separate databases. Various inferencing mechanisms (for example a rule engine) draw conclusions from the database. Other databases request consults (conclusions about the database). This structure allows the data and the inferencing in each partition to evolve with limited interaction with other databases. Other important structures include: credentialing and "role of" allowing a human user to enter data in an object and limited accesses to specific objects respectively, modeling the role of the physical setting on the care provided, and using the problem list to order and guide the evaluation of patient care.
Previously, we have presented electrophysiological evidence reaffirming the existence of a controversial hippocampal pathway. These fibers are part of the perforant pathway and terminate directly on ...the CA1 cells. We now report that, in the hippocampal slice preparation, tetanic stimulation of the perforant pathway produces long-term potentiation (LTP) of CA1 cell responses. LTP of population spikes varied from 150% to 500%. The results were of interest because these axons synapse at distal sites on the apical dendrite. This location is usually thought to be a difficult site to evoke action potentials.
Electrophysiological techniques were used to investigate the effect of stimulating the perforant pathway (PP) on pyramidal neurons in the CA1 region of the hippocampal slice. Stimulation of the PP ...evoked both field potentials and single unit discharges in the pyramidal cell layer of the CA1 region. Several lines of experimental evidence suggest that the CA1 response does not involve granule or CA3 neurons: (i) movement of the recording electrode in the CA1 region away from the site of stimulation in the PP and closer to the CA3 region increased the latency of the evoked potential; (ii) the sum of latencies of the individual pathways in a trisynaptic circuit - from the PP to granule cells to CA3 neurons to CA1 neurons - was 2-3 times longer than the latency of the PP evoked response recorded in the CA1 region: (iii) lesioning the mossy fiber pathway or excising the CA3 region did not inhibit the CA1 response to PP stimulation. Other experimental results suggest that the PP activation of CA1 pyramidal neurons involves a direct synaptic pathway: (i) PP stimulation evoked potentials with similar latencies in the dentate gyrus and the CA1 region; (ii) the CA1 response was abolished in a Krebs' solution containing low calcium/high magnesium; (iii) excising a portion of the CA1 region between the stimulating electrode in the PP and the CA1 recording electrode, but sparing the PP, did not abolish the CA1 response; (iv) electrolytic lesions of the PP abolished the CA1 response to PP stimulation, but did not affect the CA1 response to stimulation of the CA3 region. The data suggest that fibers in the PP make direct synaptic connection with pyramidal neurons in the CA1 region of the hippocampus.
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