Measuring and Compensating for Transport Delay in Real-time Interactive Driving Simulation

Real-time, man-in-the-loop simulators are important tools for operator training as well as human performance research. Simulator implementation using digital computers offers many important advantages but may also cause problems. One of the most significant and troublesome artifacts of digital computer simulation is the presence of transport delays in the operator/vehicle control loop. Transport delays have been shown to destabilize the system, resulting in poorer control of the simulated vehicle. They may also contribute to an increased likelihood of simulator sickness in human operators. Therefore, it is desirable to be able to quantify simulator transport delays and to compensate the system in such a way that delay effects on operator performance and well-being are minimized. The research presented in this dissertation involved the measurement of simulator transport delay using two different methods: a time-domain approach involving the detection of a response to a simulated step control input, and a frequency-domain approach involving the measurement of phase shift from a simulated sinusoidal input. Algorithmic compensators (digital filters) were developed to provide phase lead to counteract the system transport delay. Two compensators designed using approaches previously described in the literature canceled out delay reasonably well; however, a new compensator design developed by the author provided more nearly ideal phase performance without introducing unwanted side effects such as visual jitter. The transport delay measurement and compensation techniques were applied to a low-cost, real-time interactive automobile driving simulator developed at the University of Central Florida. The investigations using both measurement techniques revealed that a substantial amount of delay was present in the system. The three delay compensators implemented in the simulator were found (by reapplication of the frequency-domain or steady-state delay measurement technique) to operate approximately as designed. Finally, a driver-in-the-loop experiment was conducted to assess the effect of delay compensation on driver/vehicle performance. While the small size of the experiment allowed no definite conclusions to be drawn regarding the efficacy of compensation, trends in the data were generally indicative of better performance with compensation

Integration of the Shuttle RMS/CBM Positioning Virtual Environment Simulation

Constructing the International Space Station, or other structures, in space presents a number of problems. In particular, payload restrictions for the Space Shuttle and other launch mechanisms prohibit assembly of large space-based structures on Earth. Instead, a number of smaller modules must be boosted into orbit separately and then assembled to form the final structure. The assembly process is difficult, as docking interfaces such as Common Berthing Mechanisms (CBMS) must be precisely positioned relative to each other to be within the "capture envelope" (approximately +/- 1 inch and +/- 0.3 degrees from the nominal position) and attach properly. In the case of the Space Station, the docking mechanisms are to be positioned robotically by an astronaut using the 55-foot-long Remote Manipulator System (RMS) robot arm. Unfortunately, direct visual or video observation of the placement process is difficult or impossible in many scenarios. One method that has been tested for aligning the CBMs uses a boresighted camera mounted on one CBM to view a standard target on the opposing CBM. While this method might be sufficient to achieve proper positioning with considerable effort, it does not provide a high level of confidence that the mechanisms have been placed within capture range of each other. It also does nothing to address the risk of inadvertent contact between the CBMS, which could result in RMS control software errors. In general, constraining the operator to a single viewpoint with few, if any, depth cues makes the task much more difficult than it would be if the target could be viewed in three-dimensional space from various viewpoints. The actual work area could be viewed by an astronaut during EVA; however, it would be extremely impractical to have an astronaut control the RMS while spacewalking. On the other hand, a view of the RMS and CBMs to be positioned in a virtual environment aboard the Space Shuttle orbiter or Space Station could provide similar benefits more safely and conveniently with little additional cost. In order to render and view the RMS and CBMs in a virtual world, the position and orientation of the end effector in three-dimensional space must be known with a high degree of accuracy. A precision video alignment sensor has been developed which can determine the position and orientation of the controlled element relative to the target CBM within approximately one-sixteenth inch and 0.07 angular degrees. Such a sensor could replace or augment the boresighted camera mentioned above. The computer system used to render the virtual world and the position tracking systems which might be used to monitor the user's movements (in order to adjust the viewpoint in virtual space) are small enough to carry to orbit. Thus, such a system would be feasible for use in constructing structures in space

Virtual Environment User Interfaces to Support RLV and Space Station Simulations in the ANVIL Virtual Reality Lab

Several virtual reality I/O peripherals were successfully configured and integrated as part of the author's 1997 Summer Faculty Fellowship work. These devices, which were not supported by the developers of VR software packages, use new software drivers and configuration files developed by the author to allow them to be used with simulations developed using those software packages. The successful integration of these devices has added significant capability to the ANVIL lab at MSFC. In addition, the author was able to complete the integration of a networked virtual reality simulation of the Space Shuttle Remote Manipulator System docking Space Station modules which was begun as part of his 1996 Fellowship. The successful integration of this simulation demonstrates the feasibility of using VR technology for ground-based training as well as on-orbit operations

[Die nächtliche Heerschau <dt.>] La revue nocturne

Eine Lithografie mit einem von Alexandre Dumas (1802-1870) handgeschriebenen Gedicht ist bei Aufräumarbeiten im Archivzentrum der Universitätsbibliothek Frankfurt am Main gefunden worden. Es handelt sich dabei um das Gedicht "La Revue Nocturne", Dumas' wortgetreue Übersetzung des Gedichts "Die nächtliche Heerschau" von Joseph Christian Freiherr von Zedlitz (1796-1869) ins Französische, das Dumas auf den breiten Rand der Lithografie schrieb

Missense-depleted regions in population exomes implicate ras superfamily nucleotide-binding protein alteration in patients with brain malformation.

Genomic sequence interpretation can miss clinically relevant missense variants for several reasons. Rare missense variants are numerous in the exome and difficult to prioritise. Affected genes may also not have existing disease association. To improve variant prioritisation, we leverage population exome data to identify intragenic missense-depleted regions (MDRs) genome-wide that may be important in disease. We then use missense depletion analyses to help prioritise undiagnosed disease exome variants. We demonstrate application of this strategy to identify a novel gene association for human brain malformation. We identified de novo missense variants that affect the GDP/GTP-binding site of ARF1 in three unrelated patients. Corresponding functional analysis suggests ARF1 GDP/GTP-activation is affected by the specific missense mutations associated with heterotopia. These findings expand the genetic pathway underpinning neurologic disease that classically includes FLNA. ARF1 along with ARFGEF2 add further evidence implicating ARF/GEFs in the brain. Using functional ontology, top MDR-containing genes were highly enriched for nucleotide-binding function, suggesting these may be candidates for human disease. Routine consideration of MDR in the interpretation of exome data for rare diseases may help identify strong genetic factors for many severe conditions, infertility/reduction in reproductive capability, and embryonic conditions contributing to preterm loss

Reconstructing phase-resolved hysteresis loops from first-order reversal curves

The first order reversal curve (FORC) method is a magnetometry based technique used to capture nanoscale magnetic phase separation and interactions with macroscopic measurements using minor hysteresis loop analysis. This makes the FORC technique a powerful tool in the analysis of complex systems which cannot be effectively probed using localized techniques. However, recovering quantitative details about the identified phases which can be compared to traditionally measured metrics remains an enigmatic challenge. We demonstrate a technique to reconstruct phase-resolved magnetic hysteresis loops by selectively integrating the measured FORC distribution. From these minor loops, the traditional metrics - including the coercivity and saturation field, and the remanent and saturation magnetization - can be determined. In order to perform this analysis, special consideration must be paid to the accurate quantitative management of the so-called reversible features. This technique is demonstrated on three representative materials systems, high anisotropy FeCuPt thin-films, Fe nanodots, and SmCo/Fe exchange spring magnet films, and shows excellent agreement with the direct measured major loop, as well as the phase separated loops

Lifestyle Interventions Targeting Body Weight Changes during the Menopause Transition: A Systematic Review

Objective. To determine the effectiveness of exercise and/or nutrition interventions and to address body weight changes during the menopause transition. Methods. A systematic review of the literature was conducted using electronic databases, grey literature, and hand searching. Two independent researchers screened for studies using experimental designs to evaluate the impact of exercise and/or nutrition interventions on body weight and/or central weight gain performed during the menopausal transition. Studies were quality appraised using Cochrane risk of bias. Included studies were analyzed descriptively. Results. Of 3,564 unique citations screened, 3 studies were eligible (2 randomized controlled trials, and 1 pre/post study). Study quality ranged from low to high risk of bias. One randomized controlled trial with lower risk of bias concluded that participation in an exercise program combined with dietary interventions might mitigate body adiposity increases, which is normally observed during the menopause transition. The other two studies with higher risk of bias suggested that exercise might attenuate weight loss or weight gain and change abdominal adiposity patterns. Conclusions. High quality studies evaluating the effectiveness of interventions targeting body weight changes in women during their menopause transition are needed. Evidence from one higher quality study indicates an effective multifaceted intervention for women to minimize changes in body adiposity

Family business succession in different national contexts: a fuzzy-set QCA approach

Family business succession is a key topic that has attracted considerable attention from researchers, especially in the last decade. Most research, however, is based on case studies with limited applicability and fails to present comparisons across international contexts that highlight di erences in succession processes. We apply expectation states theory to analyze a sample of 128 observations in two Southern European countries, Portugal and Greece. We study configurations of successors’ characteristics, family business characteristics, the existence (or absence) of a succession plan, and successors’ motivation to succeed. Our aim is to reveal how these issues a ect successors’ perceptions of preparation for succession using fuzzy-set qualitative comparative analysis (fsQCA). Family businesses are a dominant organizational form all over the world, and succession issues are critical for the sustainability of family businesses. Our findings suggest that di erent configurations of conditions influence successors’ perceptions of preparation for family business succession. Moreover, we verify the influence of cultural di erences on these processes. This research helps fill a gap in the literature, showing the role of a set of characteristics in successors’ perceptions of preparation for family business succession. Our conclusions provide insight into the types of policies that can promote successful family business succession.The data for this study were collected as part of FABUSS (www.fabuss-project.eu), an ERASMUS+ project (2016-3-EL02-KA205-002673) aimed at evaluating the conditions for successful succession in European family businesses.info:eu-repo/semantics/publishedVersio