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1. Optical dipole trapping of Holmium

   Yip, C. ; Booth, D. ; Zhou, H. ; Collett, J. ; Hostetter, J. ; Saffman, M. ( January 2018 , 49th annual meeting of the APS division of Atomic, Molecular, & optical physics)

   Neutral Holmiums 128 ground hyperfine states, the most of any non-radioactive element, is a test bed for quantum con- trol of a very high dimensional Hilbert space, and offers a promising platform for quantum computing. Previously we have cooled Holmium atoms in a MOT on a 410.5 nm transition and characterized its Ry- dberg spectra. We report here on the first optical dipole trapping of Holmium with a 532 nm wavelength trap laser. The trap lifetime is close to 1 sec., limited by photon scattering from nearby transitions. The trapped atoms are used to measure the dynamic scalar and tensor polarizabilities which are compared with calculations based on measured oscillator strengths. We also report progress towards narrow line cooling and magnetic trapping of single atoms. 

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2. How Will Drivers Take Back Control in Automated Vehicles? A Driving Simulator Test of an Interleaving Framework

   https://doi.org/10.1145/3409118.3475128  

   Nagaraju, Divyabharathi ; Ansah, Alberta ; Ch, Nabil Al ; Mills, Caitlin ; Janssen, Christian P. ; Shaer, Orit ; Kun, Andrew L ( September 2021 , AutomotiveUI 2021)

   null (Ed.)

   We explore the transfer of control from an automated vehicle to the driver. Based on data from N=19 participants who participated in a driving simulator experiment, we find evidence that the transfer of control often does not take place in one step. In other words, when the automated system requests the transfer of control back to the driver, the driver often does not simply stop the non-driving task. Rather, the transfer unfolds as a process of interleaving the non-driving and driving tasks. We also find that the process is moderated by the length of time available for the transfer of con- trol: interleaving is more likely when more time is available. Our interface designs for automated vehicles must take these results into account so as to allow drivers to safely take back control from automation. 

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3. Decoupled Data-Based Approach for Learning to Control Nonlinear Dynamical Systems

   https://doi.org/10.1109/TAC.2021.3108552  

   Wang, Ran ; Parunandi, Karthikeya Sharma ; Yu, Dan ; Kalathil, Dileep ; Chakravorty, Suman ( August 2021 , IEEE Transactions on Automatic Control)

   This paper addresses the problem of learning the optimal control policy for a nonlinear stochastic dynam- ical. This problem is subject to the ‘curse of dimension- ality’ associated with the dynamic programming method. This paper proposes a novel decoupled data-based con- trol (D2C) algorithm that addresses this problem using a decoupled, ‘open-loop - closed-loop’, approach. First, an open-loop deterministic trajectory optimization problem is solved using a black-box simulation model of the dynamical system. Then, closed-loop control is developed around this open-loop trajectory by linearization of the dynamics about this nominal trajectory. By virtue of linearization, a linear quadratic regulator based algorithm can be used for this closed-loop control. We show that the performance of D2C algorithm is approximately optimal. Moreover, simulation performance suggests a significant reduction in training time compared to other state of the art algorithms. 

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4. The effect of F10.7 on interhemispheric differences in ionospheric current during solstices

   https://doi.org/10.1016/j.asr.2022.02.006  

   James, Tre'Shunda ( February 2022 , Advances in space research)

   We investigate the differences in the electrojet and Birkeland current systems during summer and winter solstice and the effect of F10.7. The difference in solar illumination of the polar ionosphere during the winter versus summer solstice results in significantly higher conductivity in the summer polar ionosphere. As expected, the currents are larger during the summer than during the winter. The rela- tionship between the electrojets and the Birkeland current systems is essentially constant across seasons, as expected if the ionospheric electrojets close the Birkeland currents. The magnitude of F10.7 is an indicator of the level of solar-generated ionospheric conductance, therefore, one would expect larger ionospheric currents during periods of larger F10.7. This holds true for the summer solstice periods, however, the opposite trend is observed during the winter solstice periods. We provide an explanation for this finding based on the con- trol of the dayside merging rate by the magnetosheath flow pattern. 

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5. Performance Evaluation of WebRTCbased Video Conferencing

   Bart Jansen, Timothy Goodwin ( January 2017 , IFIP Performance '17)

   WebRTC has quickly become popular as a video conferenc- ing platform, partly due to the fact that many browsers support it. WebRTC utilizes the Google Congestion Con- trol (GCC) algorithm to provide congestion control for real- time communications over UDP. The performance during a WebRTC call may be in uenced by several factors, includ- ing the underlyingWebRTC implementation, the device and network characteristics, and the network topology. In this paper, we perform a thorough performance evaluation of WebRTC both in emulated synthetic network conditions as well as in real wired and wireless networks. Our evaluation shows that WebRTC streams have a slightly higher priority than TCP ows when competing with cross trac. In gen- eral, while in several of the considered scenarios WebRTC performed as expected, we observed important cases where there is room for improvement. These include the wireless domain and the newly added support for the video codecs VP9 and H.264 that does not perform as expected. 

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