Deepak Vembar

Evaluation of interaction devices for projector based virtual reality aircraft inspection training environments

The Aircraft maintenance and inspection is a complex system wherein humans play a key role in ensuring the worthiness of the aircraft. Traditional visual inspection training consisted mainly of on-the-job training (OJT). While OJT provides novice inspectors with the hands-on experience critical to effective transfer, it lacks the ability to provide real-time feedback and exposure to various scenarios in which to inspect. With advances in technology, computer simulators have been developed to train the novice inspector and reduce the learning curve inherent with transitioning from the classroom to the workforce. Advances in graphics and virtual reality (VR) technology have allowed for an increase the sense of involvement in using these simulators. Though these simulators are effective, their deployment in aircraft maintenance training schools is limited by the high cost of VR equipment. This research investigates the effectiveness of different interaction devices for providing projector based simulated aircraft maintenance inspection training.

GEN05-6: Assessing the Impact of Multiple Active Queue Management Routers

Recent studies have shown that a non-negligible number of packets face multiple congested links on Internet paths. We investigate the impact of using multiple active queue management (AQM) routers on paths that consist of multiple congested links. We present the results of an ns-2 evaluation study of various AQM techniques that, in contrast to previous studies of AQM, uses a complex network topology including up to three congested links, reverse path traffic, and realistic round-trip times. We consider the effects of multiple AQM routers coupled with explicit congestion notification (ECN) on the throughput of long-lived flows and response times of web traffic. We find that, especially for web traffic, performance is improved as the number of AQM routers is increased, but that significant improvements occur with even a single AQM router.

Evaluation of Interaction Devices for Ndi Training in Vr: Gamepad Vs. Joystick

Recent advances have led to the development of a virtual simulator to be used for non-destructive inspection (NDI) training of aviation maintenance technicians. The simulator is distinctive in that it has been developed to simulate a general type of NDI job aiding tool (video borescope), as opposed to only simulating a precise model and make. By generating a simulator based on a generic model of the video borescope, the development process must face a common hurdle: determining the best interaction device for the task at hand. In the real world, video borescopes come in a variety of shapes and sizes, as do their interaction devices. In this case, the team must decide upon the best interaction device to be used while ensuring the retention of inspection information from training and facilitating interaction ease of use, all while not permanently engraining the skills that will be needed to control the actual devices when actually used. In short, the interaction device chosen for this simulator should facilitate the trainees ability to learn NDI techniques without hardwiring simulator control techniques which can vary greatly in the real world. In an effort to determine the most applicable interaction device for this generic training simulator, a study was conducted using expert inspectors and two common interaction devices: a gamepad and a joystick. Performance measures were collected and subjective measures, by way of post-test questionnaires, were considered as well. This paper details the evaluation of a gamepad and a joystick as interaction devices when used with a virtual video borescope simulator for inspection training. Following the findings identified in the study, recommendations are provided for the implementation of such devices.

AQM performance in multiple congested link networks

TCP Reno, the most widely used implementation on the Internet, uses retransmission timeouts and the receipt of three duplicate ACKs to detect packet loss in the network. In case of multiple congested links, it is important to detect packet losses as early as possible in order to prevent unnecessary timeouts and retransmits. Active Queue Management (AQM) schemes seek to improve the overall user response time by using queue build-ups at the routers to detect congestion. Previous research has focused on determining the effects of AQM schemes on HTTP/1.0 traffic in single congested link networks [2]. In this experiment, we evaluated the performance of TCP Reno with drop-tail routers and ECN-enabled TCP with Selective Acknowledgements (SACK) [5] over Adaptive Random Early Detection (ARED) [4] routers in a multiple congested link network.