Whirl Flutter and the Development of the NASA X-57 Maxwell

The X-57 Maxwell is NASAs all-electric demonstration vehicle. The primary demonstration objective of this flight test program is to show a factor of five reduction in energy consumption. The vehicle includes two large wing tip propellers designed to provide propul- sion at cruise conditions and twelve leading edge propellers designed to operate at high lift conditions. The first configuration of the vehicle that will be flight tested has the large wing tip propellers relocated to an inboard wing station. A simplified structural dynamic model of the propulsion system has been generated and coupled with a beam model of the vehicle. Whirl flutter analyses have been performed, examining the stability of the isolated propulsion system and coupled to the beam model of the vehicle. Trimmed flight scenarios for the vehicle include straight and level flight and zero power windmilling conditions. The whirl flutter analyses for this configuration indicate that the configuration will be free of whirl flutter within the required flight envelope

A Letter of W[illiam] B. Gilmore to A. C. V. R.

A letter of W[illiam] B. Gilmore to A.C.V.R., reporting on some property matters. Gilmore refers to a Mr. S. whom I assume is Samuel Schieffelin. Gilmore is hopeful also that the academy of which he is the principal will thrive. He gives evidence of a warm piety in his letter. Gilmore is married to a daughter of the Van Raaltes.https://digitalcommons.hope.edu/vrp_1870s/1042/thumbnail.jp

Universal time-evolution of a Rydberg lattice gas with perfect blockade

We investigate the dynamics of a strongly interacting spin system that is motivated by current experimental realizations of strongly interacting Rydberg gases in lattices. In particular we are interested in the temporal evolution of quantities such as the density of Rydberg atoms and density-density correlations when the system is initialized in a fully polarized state without Rydberg excitations. We show that in the thermodynamic limit the expectation values of these observables converge at least logarithmically to universal functions and outline a method to obtain these functions. We prove that a finite one-dimensional system follows this universal behavior up to a given time. The length of this universal time period depends on the actual system size. This shows that already the study of small systems allows to make precise predictions about the thermodynamic limit provided that the observation time is sufficiently short. We discuss this for various observables and for systems with different dimensions, interaction ranges and boundary conditions.Comment: 16 pages, 3 figure

Cost-Effectiveness of Bosutinib for the Treatment of Adult Patients with Chronic Phase Chronic Myeloid Leukemia in the Second-Line Setting

Background A recently conducted matching-adjusted indirect comparison demonstrated that bosutinib improved progression-free survival, and delayed progression to advanced disease compared with dasatinib and nilotinib in patients with second line (2L) chronic-phase chronic myeloid leukemia (CP-CML). However, the long-term clinical and economic impact of using bosutinib versus dasatinib and nilotinib has not been evaluated. The objective was to determine the cost-effectiveness of bosutinib compared with dasatinib and bosutinib compared with nilotinib from a US payer perspective. Methods A cost-effectiveness model was developed using partition survival methods and three health states: progression-free, progression, and death. Trial data (individual patient-level and aggregate-level data) informed the progression-free and overall survival estimates. Costs included drugs and medical resource use. Utility values were obtained from literature. Sensitivity analyses (SAs) included one-way and probabilistic sensitivity analyses (PSAs). Results Comparing bosutinib versus dasatinib resulted in a gain of 0.4 discounted life years, 1.5 quality-adjusted life years (QALYs), and incremental costs of $28,459 (values in 2020 US dollars), for an incremental cost-effectiveness ratio (ICER) of$19,811/QALY gained. Comparing bosutinib versus nilotinib resulted in a gain of 0.8 discounted life-years, 1.8 QALYs, and incremental costs of $76,563, for an ICER of$41,932/QALY gained. Drug costs and extrapolation distribution type were the main drivers of the model in the one-way SAs. In the PSAs, bosutinib had >90% and >80% probabilities of being cost-effective at a willingness-to-pay threshold of $100,000/QALY versus dasatinib and nilotinib, respectively. Conclusions Our results suggest that compared with dasatinib and nilotinib, bosutinib may represent good value for money for treating 2L CP-CML patients

Acoustically driven ferromagnetic resonance

Surface acoustic waves (SAW) in the GHz frequency range are exploited for the all-elastic excitation and detection of ferromagnetic resonance (FMR) in a ferromagnetic/ferroelectric (nickel/lithium niobate) hybrid device. We measure the SAW magneto-transmission at room temperature as a function of frequency, external magnetic field magnitude, and orientation. Our data are well described by a modified Landau-Lifshitz-Gilbert approach, in which a virtual, strain-induced tickle field drives the magnetization precession. This causes a distinct magnetic field orientation dependence of elastically driven FMR that we observe in both model and experiment.Comment: 4 page

Aeroservoelastic Testing of a Sidewall Mounted Free Flying Wind-Tunnel Model

A team comprised of the Air Force Research Laboratory (AFRL), Northrop Grumman, Lockheed Martin, and the NASA Langley Research Center conducted three j wind-tunnel tests in the Transonic Dynamics Tunnel to demonstrate active control technologies relevant to large, exible vehicles. In the rst of these three tests, a semispan, aeroelastically scaled, wind-tunnel model of a ying wing SensorCraft vehi- cle was mounted to a force balance to demonstrate gust load alleviation. In the second and third tests, the same wing was mated to a new, multi-degree-of-freedom, sidewall mount. This mount allowed the half-span model to translate vertically and pitch at the wing root, allowing better simulation of the full span vehicle's rigid-body modes. Gust Load Alleviation (GLA) and Body Freedom Flutter (BFF) suppression were successfully demonstrated. The rigid body degrees-of-freedom required that the model be own in the wind tunnel using an active control system. This risky mode of testing necessitated that a model arrestment system be integrated into the new mount. The safe and successful completion of these free-flying tests required the development and integration of custom hardware and software. This paper describes the many systems, software, and procedures that were developed as part of this effort

Overview of the Aeroelastic Prediction Workshop

The Aeroelastic Prediction Workshop brought together an international community of computational fluid dynamicists as a step in defining the state of the art in computational aeroelasticity. This workshop's technical focus was prediction of unsteady pressure distributions resulting from forced motion, benchmarking the results first using unforced system data. The most challenging aspects of the physics were identified as capturing oscillatory shock behavior, dynamic shock-induced separated flow and tunnel wall boundary layer influences. The majority of the participants used unsteady Reynolds-averaged Navier Stokes codes. These codes were exercised at transonic Mach numbers for three configurations and comparisons were made with existing experimental data. Substantial variations were observed among the computational solutions as well as differences relative to the experimental data. Contributing issues to these differences include wall effects and wall modeling, non-standardized convergence criteria, inclusion of static aeroelastic deflection, methodology for oscillatory solutions, post-processing methods. Contributing issues pertaining principally to the experimental data sets include the position of the model relative to the tunnel wall, splitter plate size, wind tunnel expansion slot configuration, spacing and location of pressure instrumentation, and data processing methods