ABSTRACT
In this paper, we present the technical design of a virtual CAN network system allowing engineers from different sites to work on a single CAN segment. The system was originally developed for interconnecting students in online university classes, due to COVID-19 pandemic – to learn together the principles of SAE J1939 and ISO 11783 technologies in guided programming exercises. The developed system is based on a centralized server located on the university network and multiple clients connecting to the central server. The protocol to tunnel CAN messages is based on TCP/IP. The unsecured CAN tunnel operates in a secured VPN tunnel. The system design leverages virtual CAN channels provided by two dongle manufactures: Kvaser and Vector – this driver level technology also allows easy access of PC software to the virtual CAN network without any physical CAN hardware. Within the university network, round trip times of under 50 ms were recorded between bus segments when all users were in Germany. © 2022, VDI Verlag GMBH. All rights reserved.
ABSTRACT
We present the deployment of a seismic network in the Helsinki capital area of Finland that was installed to monitor the response to the second stimulation phase of an similar to 6-kilometer-deep enhanced geothermal system in 2020. The network consists of a dozen permanent broadband stations and more than 100, predominantly short-period, temporary stations. This 2020 deployment is characterized by a mix of single stations and arrays with diverse configurations. It covers a larger area and exhibits a smaller azimuthal gap compared with the network that monitored the first stimulation in 2018. We surveyed the outcropping rocks at one of the large array sites to study surface expressions of shear or weakness zones that are possibly connected to the stimulated volume at depth. We link the relatively large number of macroseismic reports received during the stimulation to an increased public awareness of the project together with an increased sensitivity because the second stimulation occurred during the local COVID-19 mobility restrictions. The spatial distribution of the reports seems to be controlled by the radiation pattern of the induced earthquakes and hence by the stress state in the reservoir. The continuous records contain strong energy at high frequencies above 50 Hz that is attributed to anthropogenic processes in the densely populated urban area. However, the exceptionally low attenuation of the bedrock yields good signal-to-noise ratio seismograms of the induced small events, the largest of which was magnitude M-L 1.2. The signal quality of the obtained noise correlation functions is similarly very good. The data set has been collected to underpin a wide range of seismic analysis techniques for complementary scientific studies of the evolving reservoir processes and the induced event properties. These scientific studies should inform the legislation and educate the public for transparent decision making around geothermal power generation.