A Search for Vector Magnetic Field Variations Associated with the M-Class Flares of 1991 June 10 in AR 6659

A careful analysis of a 6-hour time sequence of vector magnetograms of AR 6659, observed on 1991 June 10 with the MSFC vector magnetograph, has revealed only minor changes in the vector magnetic field azimuths in the vicinity of two M-class flares, and the association of these changes with the flares is not unambiguous. In this paper we present our analysis of the data which includes comparison of vector magnetograms prior to and during the flares, calculation of distributions of the rms variation of the azimuth at each pixel in the field of view of the active region, and examination of the variation with time of the azimuths at every pixel covered by the main flare emissions as observed with the H-alpha telescope coaligned with the vector magnetograph. We also present results of an analysis of evolutionary changes in the azimuth over the field of view of the active region

Towards an Immersive Driving Simulator to Study Factors Related to Cybersickness

What makes a good cybersickness testbed great? In this work, we discuss the characteristics of a high fidelity, realistic immersive virtual reality driving simulator developed to study cybersickness, a malady that is caused as a consequence of Virtual Reality usage. The simulator’s feasibility was evaluated by conducting a preliminary study. Results suggest that our platform is reliable and robust, making for an excellent testbed/ platform to study factors associated with cybersickness in Immersive Virtual Environments

Challenges in Clock Synchronization for On-Site Coding Digital Beamformer

Typical radio frequency (RF) digital beamformers can be highly complex. In addition to a suitable antenna array, they require numerous receiver chains, demodulators, data converter arrays, and digital signal processors. To recover and reconstruct the received signal, synchronization is required since the analog-to-digital converters (ADCs), digital-to-analog converters (DACs), field programmable gate arrays (FPGAS), and local oscillators are all clocked at different frequencies. In this article, we present a clock synchronization topology for a multichannel on-site coding receiver (OSCR) using the FPGA as a master clock to drive all RF blocks. This approach reduces synchronization errors by a factor of 8, when compared to conventional digital beamformer

A personal-computer-based imaging Stokes polarimeter for solar observations

For measurements of vector magnetic field over solar active regions, a Stokes polarimeter for studying the polarisation profiles on selected spectral lines is described. This paper gives details of the relevant CCD imaging system and the personal computer (PC)-based acquisition, together with the image analysis techniques necessary for the task. Field trials and tests of the system are also described