Understanding, predicting and supressing the inadvertent aircraft oscillations caused by Aircraft/Rotorcraft Pilot Couplings (A/RPC) is a challenging problem for designers. These are potential ...instabilities that arise from the effort of controlling aircraft with high response actuation systems. The present paper reviews, updates and discusses desirable practices to be used during the design process for unmasking A/RPC phenomena. These practices are stemming from the European Commission project ARISTOTEL Aircraft and Rotorcraft Pilot Couplings – Tools and Techniques for Alleviation and Detection (2010–2013) and are mainly related to aerodynamic and structural modelling of the aircraft/rotorcraft, pilot modelling and A/RPC prediction criteria. The paper proposes new methodologies for precluding adverse A/RPCs events taking into account the aeroelasticity of the structure and pilot biodynamic interaction. It is demonstrated that high-frequency accelerations due to structural elasticity cause negative effects on pilot control, since they lead to involuntary body and limb-manipulator system displacements and interfere with pilot's deliberate control activity (biodynamic interaction) and, finally, worsen handling quality ratings.
A pilot or preliminary study is referred to a small-scale of a complete survey or a pretest for a particular research instrument such as a questionnaire or interview guide (1). Pilot studies could be ...conducted in qualitative, quantitative, and even mixed methods research (2). General application of pilot studies can be summarized in four areas: 1) to find problems and barriers related to participants' recruitment; 2) being engaged in research as a qualitative researcher; 3) assessing the acceptability of observation or interview protocol; and 4) to determine epistemology and methodology of research. Three specific functions of pilot studies in qualitative research are assigned to three main qualitative methodologies including phenomenology, grounded theory, and ethnography. It allows exercising epoch within the phenomenological research, increasing theoretical sensitivity in grounded theory, and familiarity with fieldwork in ethnography (3-5).
Sample size justification is an important consideration when planning a clinical trial, not only for the main trial but also for any preliminary pilot trial. When the outcome is a continuous ...variable, the sample size calculation requires an accurate estimate of the standard deviation of the outcome measure. A pilot trial can be used to get an estimate of the standard deviation, which could then be used to anticipate what may be observed in the main trial. However, an important consideration is that pilot trials often estimate the standard deviation parameter imprecisely. This paper looks at how we can choose an external pilot trial sample size in order to minimise the sample size of the overall clinical trial programme, that is, the pilot and the main trial together. We produce a method of calculating the optimal solution to the required pilot trial sample size when the standardised effect size for the main trial is known. However, as it may not be possible to know the standardised effect size to be used prior to the pilot trial, approximate rules are also presented. For a main trial designed with 90% power and two-sided 5% significance, we recommend pilot trial sample sizes per treatment arm of 75, 25, 15 and 10 for standardised effect sizes that are extra small (≤0.1), small (0.2), medium (0.5) or large (0.8), respectively.
Cetacean morbillivirus (CeMV) causes illness and death in cetaceans worldwide; the CeMV strains circulating in the Southern Hemisphere are poorly known. We detected a pilot whale CeMV strain in 3 ...short-finned pilot whales (Globicephala macrorhynchus) stranded in Brazil during July-October 2020. Our results confirm this virus circulates in this species.
Smart Pilot Assignment for Massive MIMO Zhu, Xudong; Wang, Zhaocheng; Dai, Linglong ...
IEEE communications letters,
2015-Sept., 2015-9-00, 20150901, Volume:
19, Issue:
9
Journal Article
Peer reviewed
Open access
A massive multiple-input multiple-output (MIMO) system, which utilizes a large number of antennas at the base station (BS) to serve multiple users, suffers from pilot contamination due to inter-cell ...interference. A smart pilot assignment (SPA) scheme is proposed in this letter to improve the performance of users with severe pilot contamination. Specifically, by exploiting the large-scale characteristics of fading channels, the BS first measures the inter-cell interference of each pilot sequence caused by the users with the same pilot sequence in other adjacent cells. Then, in contrast to the conventional schemes which assign the pilot sequences to the users randomly, the proposed SPA method assigns the pilot sequence with the smallest inter-cell interference to the user having the worst channel quality in a sequential way to improve its performance. Simulation results verify the performance gain of the proposed scheme in typical massive MIMO systems.
Channel estimation in time division duplexing (TDD)-based massive multiple-input multiple-output (MIMO) systems is heavily hampered by the pilot contamination, which constitutes a major bottleneck on ...the overall system performance. This study considers the pilot contamination problem in multi-cell TDD-based massive MIMO systems, and analytical expressions are presented on the normalised mean square error (NMSE) of the minimum mean square error channel estimation algorithm. Based on the obtained NMSE, this study proposes an optimal pilot assignment strategy to minimise the effect of pilot contamination. In order to further improve the system performance, a pilot design-based channel estimation scheme is proposed, where Chu sequences with perfect auto-correlation property are employed to design the optimal pilot sequences aiming at acquiring the accurate channel state information. Simulation results show that the proposed pilot assignment strategy outperforms the random pilot assignment method, and approaches to the performance of the exhaustive search method which requires high computational complexity. Moreover, the performance gain of the pilot design-based channel estimation scheme is verified in massive MIMO systems.
Abstract only Introduction Intraarterial thrombolytic treatment after mechanical thrombectomy (MT) in patients with large vessel occlusion ischemic stroke may improve the odds of achieving complete ...reperfusion and favorable functional outcome at 90 days. This study evaluated the safety and efficacy of intraarterial Tenecteplase (IA TNK) as an adjunctive therapy to mechanical thrombectomy in patients with anterior circulation large vessel occlusion. The primary safety endpoint is the rate of symptomatic ICH within 24 hours of treatment with IA TNK. The primary efficacy endpoint is the proportion of patients with improvement of reperfusion. The secondary endpoints included final revascularization grade, discharge mortality, and any intracranial hemorrhage. Methods ALLY is a prospective, single‐center, single‐arm pilot study (ClinicalTrials.gov Identifier: NCT05172934). The study enrolled adult patients ≥18 and ≤85 years with large vessel (ICA or MCA) occlusion, with pre‐morbid mRS ≤3 who underwent mechanical thrombectomy and achieved incomplete reperfusion with a final TICI score of 2b and 2C. All enrolled subjects received at least one dose of 1.5 mg IA TNK. Additional treatments were administered at the discretion of the operator to a maximum of 4.5 mg IA TNK. Treatments were administered as a bolus in 3 divided doses given 5 minutes apart, with angiographic runs obtained before and after the final treatment. All patients had imaging follow up (MRI of CT) after 24 hours of treatment. Clinical assessment was completed with NIHSS and mRS scales. Angiographic and imaging data were adjudicated by an independent core laboratory. Results ALLY is a prospective, single‐center, single‐arm pilot study (ClinicalTrials.gov Identifier: NCT05172934). The study enrolled adult patients ≥18 and ≤85 years with large vessel (ICA or MCA) occlusion, with pre‐morbid mRS ≤3 who underwent mechanical thrombectomy and achieved incomplete reperfusion with a final TICI score of 2b and 2C. All enrolled subjects received at least one dose of 1.5 mg IA TNK. Additional treatments were administered at the discretion of the operator to a maximum of 4.5 mg IA TNK. Treatments were administered as a bolus in 3 divided doses given 5 minutes apart, with angiographic runs obtained before and after the final treatment. All patients had imaging follow up (MRI of CT) after 24 hours of treatment. Clinical assessment was completed with NIHSS and mRS scales. Angiographic and imaging data were adjudicated by an independent core laboratory. Conclusion Ally pilot study demonstrated that adjunctive intraarterial Tenecteplase to mechanical thrombectomy was safe and feasible without major complications. Although there was no change in final reperfusion TICI score, there was evidence of improved distal perfusion on angiographic images.
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