Abstract

In this paper the influence of the flight control system over the off-nominal flying dynamics of a remotely operated air vehicle is evaluated. Of particular interest is the departure/upset behaviour of

Despite the significant improvement in safety linked to the fourth generation of airliners, the risk of encountering upset conditions remains an important consideration.Upset -which may arise from faults, external events or inappropriate pilot inputs spins. The analysis shows that these spirals and spins are connected in two-parameter space and that, by an inappropriate pilot reaction to the spiral, it is possible to enter the oscillatory spin.

Background The effect of a kidney transplant on a recipient extends beyond the restoration of kidney function. However, there is limited qualitative analysis of recipient perspectives on life following transplantation, particularly in the United States. To understand the full patient experience, it is necessary to understand recipient views on life adjustments after kidney transplantation, medical management, and quality of life. This could lead to improvements in recipient care and sense of well-being. Methods We conducted a paper-based survey from March 23 to October 1, 2015 of 476 kidney transplant recipients at the University of Michigan Health System in Ann Arbor, Michigan. We analyzed their open-ended responses using qualitative research methods. This is a companion analysis to a previous quantitative report on the closed-ended responses to that survey. Results Common themes relating to changes following transplantation included: improvements in quality of life, a return to normalcy, better health and more energy. Concerns included: duration of graft survival, fears about one day returning to dialysis or needing to undergo another kidney transplant, comorbidities, future quality of life, and the cost and quality of their healthcare. Many recipients were grateful for their transplant, but some were anxious about the burdens transplantation placed on their loved ones. Conclusions While most recipients reported meaningful improvements in health and lifestyle after kidney transplantation, a minority of participants experienced declines in energy or health status. Worries about how long the transplant will function, future health, and cost and quality of healthcare are prevalent. Future research could study the effects of providing additional information, programs, and interventions following transplantation that target these concerns. This may better prepare and support kidney recipients and lead to improvements in the patient experience. Electronic supplementary material The online version of this article (10.1186/s12882-019-1368-0) contains supplementary material, which is available to authorized users.

Time delays arise in most feedback systems and have specific relevance for remotely piloted vehicles with ground-based pilots and controllers. NASA's test facility for flight dynamics and control research using sub-scale vehicles, AirSTAR, has developed the remotely piloted Generic Transport Model (GTM). Analysis of a numerical model of this has previously provided insight into open-loop upset dynamics and the impact of flight controllers. However, to date, studies have not considered the effect of time delay on the system's stability. Current developments at the AirSTAR facility are aimed at testing a sub-scale generic airliner model during loss-of-control conditions over extended distances and altitudes compared to the GTM. In developing controllers for such a remotely piloted vehicle it is helpful to understand the effect of delay in the communication links and protocols. This paper utilises bifurcation analysis to evaluate the effect of delay on the closed-loop stability for the GTM numerical model with a linear quadratic regulator controller with proportional and integral components (LQR-PI). The impact of time delays in both fixed-gain and gain-scheduled versions of the controller are presented in terms of the stability of nominal and off-nominal solutions. This is followed by a discussion of stability maps, again generated by bifurcation analysis, which can be used to assess, over a wide