44 research outputs found
Review of road surface photometry methods and devices – Proposal for new measurement geometries
Specifications concerning road lighting and photometry of road surfaces were established more than 50 years ago. Road lighting design and road marking visibility were developed for vehicle driving. The observation distance defined by standards corresponds to interurban applications; however, within Europe these areas do not tend to be lit. The objective of the SURFACE project is to propose new geometries for the photometric characterisation of pavements, both adapted to different urban travel modes and new lighting technologies. This article reviews the available guidelines, standards, measuring devices and literature regarding geometries and road lighting applications, and presents the project SURFACE analysis and proposal. The SURFACE consortium recommends adding several new angles for different driving conditions and road users; 2.29 degrees for urban environments and consistency with road marking standard, and 1 degrees for extra-urban environment and consistency with previous geometries. A 5 degrees angle, corresponding to 17-m viewing distance, could be an interesting compromise, suitable for urban driving at low speed, cycling and for scooters. The angles of 10 degrees and 20 degrees are under consideration for describing the boundary between diffuse and specular behaviour
Effects of thermoregulation on human sleep patterns: A mathematical model of sleep-wake cycles with REM-NREM subcircuit
In this paper we construct a mathematical model of human sleep/wake regulation with thermoregulation and temperature e ects. Simulations of this model show features previously presented in experimental data such as elongation of duration and number of REM bouts across the night as well as the appearance of awakenings due to deviations in body temperature from thermoneutrality. This model helps to demonstrate the importance of temperature in the sleep cycle. Further modi cations of the model to include more temperature e ects on other aspects of sleep regulation such as sleep and REM latency are discussedPostprint (author's final draft
DĂ©flection measurement : The neef of a continuous and full view approach
Road pavement bearing capacity is a crucial point for road maintenance and rehabilitation. Maximum deflection is usually measured discontinuously by mechanical sensors at low speed which implies safety problems. Pavement simulations showed that some parameters describing the deflection basin are more sensitive to pavement damages (cracking or delamination) than the maximum deflection. A direct measurement of surface deflection could be very useful to estimate such parameters. A new measurement system based on an imaging technology is presented. It consists in the projection of a structured pattern on the road surface A camera analyses the pattern deformation, which allows for measuring a surface deflection. The technique has been laboratory qualified in order to measure shapes, displacements and slopes on a road. A first experiment was carried out with a static system on the LCPC test track. The imaging technique was able to measure a surface deflection with satisfactory metrological performance
ACCURACY ASSESSMENT OF A CANAL-TUNNEL 3D MODEL BY COMPARING PHOTOGRAMMETRY AND LASERSCANNING RECORDING TECHNIQUES
With recent developments in the field of technology and computer science, conventional methods are being supplanted by laser scanning
and digital photogrammetry. These two different surveying techniques generate 3-D models of real world objects or structures. In this
paper, we consider the application of terrestrial Laser scanning (TLS) and photogrammetry to the surveying of canal tunnels. The
inspection of such structures requires time, safe access, specific processing and professional operators. Therefore, a French partnership
proposes to develop a dedicated equipment based on image processing for visual inspection of canal tunnels. A 3D model of the vault
and side walls of the tunnel is constructed from images recorded onboard a boat moving inside the tunnel. To assess the accuracy of
this photogrammetric model (PM), a reference model is build using static TLS. We here address the problem comparing the resulting
point clouds. Difficulties arise because of the highly differentiated acquisition processes, which result in very different point densities.
We propose a new tool, designed to compare differences between pairs of point cloud or surfaces (triangulated meshes). Moreover,
dealing with huge datasets requires the implementation of appropriate structures and algorithms. Several techniques are presented :
point-to-point, cloud-to-cloud and cloud-to-mesh. In addition farthest point resampling, octree structure and Hausdorff distance are
adopted and described. Experimental results are shown for a 475 m long canal tunnel located in France
DEVISING A VISUAL INSPECTION SYSTEM FOR CANAL TUNNELS: PRELIMINARY STUDIES
International audienc
Metrology of Road Surface for Smart Lighting
The knowledge of the luminance coefficient q or of the reduced luminance coefficient r of road surface is an unavoidable requirement for designing road lighting installations able to assure adequate road luminance for visual conditions, energy consumption and traffic safety according to standard requirements. Unfortunately q available data refers to measurements made during the seventies with no traceability or measurement uncertainty. In the last 40 years the road surfaces pavements evolved as well the road lighting sources and luminaires. EMPIR project SURFACE will provide validated, optimised and reliable geometrical conditions for the measurement of q as well as reference data representative of current road pavements and future needs, as support of the European Standardisation process, CIE and European Metrology infrastructure.EMPIR 16NRM02 Surface, Pavement surface characterisation for smart and efficient roa
BDNF regulates the expression and traffic of NMDA receptors in cultured hippocampal neurons
The neurotrophin BDNF regulates the activity-dependent modifications of synaptic strength in the CNS. Physiological and biochemical evidences implicate the NMDA glutamate receptor as one of the targets for BDNF modulation. In the present study, we investigated the effect of BDNF on the expression and plasma membrane abundance of NMDA receptor subunits in cultured hippocampal neurons. Acute stimulation of hippocampal neurons with BDNF differentially upregulated the protein levels of the NR1, NR2A and NR2B NMDA receptor subunits, by a mechanism sensitive to transcription and translation inhibitors. Accordingly, BDNF also increased the mRNA levels for NR1, NR2A and NR2B subunits. The neurotrophin NT3 also upregulated the protein levels of NR2A and NR2B subunits, but was without effect on the NR1 subunit. The amount of NR1, NR2A and NR2B proteins associated with the plasma membrane of hippocampal neurons was differentially increased by BDNF stimulation for 30Â min or 24Â h. The rapid upregulation of plasma membrane-associated NMDA receptor subunits was correlated with an increase in NMDA receptor activity. The results indicate that BDNF increases the abundance of NMDA receptors and their delivery to the plasma membrane, thereby upregulating receptor activity in cultured hippocampal neurons.http://www.sciencedirect.com/science/article/B6WNB-4N5TN7K-5/1/0ea25e5eae5132c7c4af4b86bd88a89