-Our group, the Center for Astronomy Signal Processing and Electronics Research (CASPER), seeks to speed the development of radio astronomy signal processing instrumentation by designing and demonstrating a scalable, upgradeable, FPGA-based computing platform and software design methodology that targets a range of realtime radio telescope signal processing applications. This project relies on a small number of modular, connectible hardware components and open-source signal processing libraries which can be reused and scaled as hardware capabilities expand. We have demonstrated the use of 10 Gb Ethernet packetization and switches to manage high-bandwidth inter-board communication. Using these tools, we have built spectrometers, correlators, beamformers, VLBI data recorders, and many other applications. Future directions for the development include a fully packetized scalable correlator, additional library and toolflow development, and a next generation of modular FPGA-based hardware.
A metal/liquid interface corrosion-reaction model is developed for the flow electrification of low-conductivity liquids in metal pipes. In the proposed model, impurity anions participate in a corrosion reaction at the wall, leaving a net positive ion concentration in the diffuse electrical double layer. Convection of this positive charge constitutes the streaming current. Theoretical calculations for the convected space charge density demonstrate a velocity-dependent entrance effect that diminishes in pipes of larger radii, in agreement with experimental data for heptane in stainless steel pipes. Far downstream, the proposed model also correctly predicts that the convected space charge density falls with increasing pipe radius. As in previous work, the convected space charge density far downstream, (I/Qec b)∞, is found to be linear with the ζ-potential. However, the proposed model is self-consistent in that the ζ-potential arises as part of the calculation and is not an adjustable constant characteristic only of the metal/hydrocarbon interface. In the entrance region, the convected space charge density is assumed to vary exponentially with axial position with the form (I/Qec b) = (I/Qec b)∞ − A(I/Qec b)1 × exp(−ας), where A is a preexponential factor, (I/Qec b)1 is a deviation function, α is a characteristic eigenvalue, and ς is the dimensionless axial coordinate. With a known value of 79.8 μm for the solution Debye length, calculations show A to be 0.075, and (I/Qec b)1 and α to be 7.98 (10-4), 1.42 (10-4), and 2.60 (10-5) and 1.242, 2.425, and 2.938, respectively, for pipe radii of 0.24, 0.58, and 1.25 mm, respectively.
The current approach to connected and autonomous driving function development and evaluation uses model-in-the-loop simulation, hardware-in-the-loop simulation and limited proving ground use, followed by public road deployment of the beta version of software and technology. The rest of the road users are involuntarily forced into taking part in the development and evaluation of these connected and autonomous driving functions in this approach. This is an unsafe, costly and inefficient method. Motivated by these shortcomings, this paper introduces the Vehicle-in-Virtual-Environment (VVE) method of safe, efficient and low-cost connected and autonomous driving function development, evaluation and demonstration. The VVE method is compared to the existing state-of-the-art. Its basic implementation for a path-following task is used to explain the method where the actual autonomous vehicle operates in a large empty area with its sensor feeds being replaced by realistic sensor feeds corresponding to its location and pose in the virtual environment. It is possible to easily change the development virtual environment and inject rare and difficult events which can be tested very safely. Vehicle-to-Pedestrian (V2P) communication-based pedestrian safety is chosen as the application use case for the VVE in this paper, and corresponding experimental results are presented and discussed. A no-line-of-sight pedestrian and vehicle moving towards each other on intersecting paths with different speeds are used in the experiments. Their time-to-collision risk zone values are compared for determining severity levels. The severity levels are used to slow down or brake the vehicle. The results show that V2P communication of pedestrian location and heading can be used successfully to avoid possible collisions. It is noted that actual pedestrians and other vulnerable road users can be used very safely in this approach.
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