Garmin (Germany)

Abstract In this work, we describe validation efforts conducted for the stellarator Monte-Carlo neutral beam and fast ion code BEAMS3D. This code is used at Wendelstein 7-X to analyze fast ion physics and has numerous integrated interfaces facilitating a wide range of applications. We use experimental fast-ion D$_\alpha$ data from the ASDEX Upgrade tokamak, covering on- and off-axis neutral beam heating phases. We obtained synthetic D$_\alpha$ spectra using the FIDASIM code, leveraging a newly developed interface that allows a distribution function from BEAMS3D to be used. Comparing the simulated distributions from BEAMS3D and the well-established NUBEAM codes to the data shows that both codes reproduce the experiment equally well given the same initial conditions. The experimental FIDA spectra are quantitatively matched. The slowing down model of BEAMS3D is thus validated and can be applied to quantitative stellarator investigations in future studies.

IoT (Internet of Things) has attracted a lot of attention recently. IoT devices need to report their data or status to base stations at various frequencies. The IoT communications observed by a base station normally exhibit the following characteristics: (1) massively connected, (2) lightly loaded per packet, and (3) periodical or at least mostly predictable. The current design principals of communication networks, when applied to IoT scenarios, however, do not fit well to these requirements. For example, an IPv6 address is 128 bits, which is much longer than a 16-bit temperature report. Also, contending to send a small packet is not cost-effective. In this work, we propose a novel framework, which is slot-based, schedule-oriented, and identity-free for uploading IoT devices' data. We show that it fits very well for IoT applications. We propose two schemes, from an ideal one to a more practical one. The main idea is to bundle time slots with certain hashing functions of device IDs, thus significantly reducing transmission overheads, including device IDs and contention overheads.