Stability analysis of motor drive interactions in aircraft electrical systems

More Electric Aircraft are currently being developed so that in the future all non-propulsive power on an aircraft can be provided by the electrical system. In this electrical system, it is expected that several motor loads will run in parallel from a single DC bus. The paper will investigate the interactions between five motor loads connected to a common DC bus, paying particular attention to the effects of the line impedance on the stability of the system, and how this interacts with any capacitance in the input filters to the motor drive loads. Based on the results of the tests carried out, guidelines to ensure the stability of a multiple load system are presented. To achieve this, a generic model for a motor load is proposed. Five of these motor loads are then connected to a DC bus and the stability of this system has been tested. The motor parameters have been scaled to represent models of different sizes, and they have different input filters. The impedance of the line has been included

Reframing global palliative care advocacy for the sustainable development goal era: A qualitative study of the views of international palliative care experts

Context The World Health Assembly Palliative Care Resolution in 2014 and the inclusion of palliative care within the sustainable development goals raised optimism that palliative care would no longer be a peripheral aspect of global health. However, no funding, accountability measures, or indicators for palliative care development accompanied these policy developments. This risks health actors continuing to prioritize the attainment of better known target-driven aspects of health care. Objectives To explore the attitudes of international palliative care experts regarding how the future development of palliative care can be accelerated. Methods About 16 international palliative care experts were interviewed for their epistemic expertise. Participants were interviewed face to face or via Skype. Interviews were recorded, transcribed nonverbatim, and analyzed using a thematic approach (NVivo). Results Participants strongly supported the rollout of national palliative care policies around the world for two reasons: to ensure palliative care attracts national funding streams and to attract global funding for palliative care. The absence of a global indicator for palliative care development was considered a severe impediment to the inclusion of palliative care within global efforts toward universal health care. Advocacy partnerships, using human rights approaches with economic frames, were considered the most effective methods of influencing policymakers. Conclusion Palliative care represents a value proposition that is not currently being maximized by advocacy. Advocates should consider palliative care developmentally, focusing on key asks for development and consider how palliative care can contribute to other international development priorities, in particular poverty reduction

Locating health diplomacy through African negotiations on performance‐based funding in global health

This article examines how national health actors in South Africa, Tanzania and Zambia perceive the participatory quality of negotiation processes associated with the performance‐based funding mechanisms of the Global Fund to Fight AIDS, Tuberculosis and Malaria and the World Bank. Through analysis of qualitative fieldwork consisting of 101 interviews within the case countries as well as in Geneva and Washington DC, the research results show that African actors within national governments generally set and negotiate performance targets of performance‐based funding schemes. Nevertheless, the results also show that the quality of those negotiations with external funders were inconsistent, suggesting the existence of asymmetrical power and influence in relation to the quality of those negotiations. This raises questions about the level of power and influence being exerted by external funders and how much leverage African political actors have available to them within global health diplomacy. It also provides evidence that certain key aspects of these negotiated processes are closed off from negotiation for African actors, therefore undermining African participation in significant ways

Atomic Model of Susy Hubbard Operators

We apply the recently proposed susy Hubbard operators to an atomic model. In the limiting case of free spins, we derive exact results for the entropy which are compared with a mean field + gaussian corrections description. We show how these results can be extended to the case of charge fluctuations and calculate exact results for the partition function, free energy and heat capacity of an atomic model for some simple examples. Wavefunctions of possible states are listed. We compare the accuracy of large N expansions of the susy spin operators with those obtained using `Schwinger bosons' and `Abrikosov pseudo-fermions'. For the atomic model, we compare results of slave boson, slave fermion, and susy Hubbard operator approximations in the physically interesting but uncontrolled limiting case of N->2. For a mixed representation of spins we estimate the accuracy of large N expansions of the atomic model. In the single box limit, we find that the lowest energy saddle-point solution reduces to simply either slave bosons or slave fermions, while for higher boxes this is not the case. The highest energy saddle-point solution has the interesting feature that it admits a small region of a mixed representation, which bears a superficial resemblance to that seen experimentally close to an antiferromagnetic quantum critical point.Comment: 17 pages + 7 pages Appendices, 14 figures. Substantial revision

Measuring the decoherence rate in a semiconductor charge qubit

We describe a method by which the decoherence time of a solid state qubit may be measured. The qubit is coded in the orbital degree of freedom of a single electron bound to a pair of donor impurities in a semiconductor host. The qubit is manipulated by adiabatically varying an external electric field. We show that, by measuring the total probability of a successful qubit rotation as a function of the control field parameters, the decoherence rate may be determined. We estimate various system parameters, including the decoherence rates due to electromagnetic fluctuations and acoustic phonons. We find that, for reasonable physical parameters, the experiment is possible with existing technology. In particular, the use of adiabatic control fields implies that the experiment can be performed with control electronics with a time resolution of tens of nanoseconds.Comment: 9 pages, 6 figures, revtex

Plasma polymerization of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl in a collisional, capacitively coupled radio frequency discharge

Plasma polymerization of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) yields thin films containing stable nitroxide radicals that have properties analogous to that of nitric oxide (NO) without short lifetimes. This property gives TEMPO films a wide variety of potential applications. Typically, control of the final film chemistry is difficult and the plasma discharge conditions must be tailored to in order to maximize the retention of these nitroxide groups during the polymerization and deposition process. In this study, plasma diagnostics and surface analysis of the deposited films were carried out to determine the optimal plasma conditions for the retention of nitroxide groups. These techniques included energy-resolved mass spectrometry, heated planar probe ion current measurements, deposition rate measurements, and x-ray photoelectron spectroscopy (XPS). Results show that operating the plasma with a combination of low input powers and high pressures produces a collisional discharge in which fragmentation of the TEMPO molecule is suppressed, leading to good retention of nitroxide groups. Ion energy distribution functions and quartz crystal microbalance measurements support the soft landing theory of ion deposition on the substrate within this γ-mode, in which the flux of low energy, soft landed ions form the primary contribution to film growth. XPS analysis of deposited polymers shows 75.7% retention of N - O groups in the polymer films deposited in a 25 Pa 5 W discharge. © 2020 Author(s)

Non-Markovian dynamics in a spin star system: The failure of thermalization

In most cases, a small system weakly interacting with a thermal bath will finally reach the thermal state with the temperature of the bath. We show that this intuitive picture is not always true by a spin star model where non-Markov effect predominates in the whole dynamical process. The spin star system consists a central spin homogeneously interacting with an ensemble of identical noninteracting spins. We find that the correlation time of the bath is infinite, which implies that the bath has a perfect memory, and that the dynamical evolution of the central spin must be non- Markovian. A direct consequence is that the final state of the central spin is not the thermal state equilibrium with the bath, but a steady state which depends on its initial state.Comment: 8 page

More haste less speed: A meta-analysis of thinking latencies during planning in people with psychosis

Cognitive impairment is a core feature of psychosis, with slowed processing speed thought to be a prominent impairment in schizophrenia and first-episode psychosis. However, findings from the Stockings of Cambridge (SOC) planning task suggest changes in processing speed associated with the illness may include faster responses in early stages of planning, though findings are inconsistent. This review uses meta-analytic methods to assess thinking times in psychosis across the available literature. Studies were identified by searching PubMed, Web of Science and Google Scholar. Eligibility criteria: 1) included a sample of people with non-affective psychosis according to DSM III, DSM IV, DSM V or ICD-10 criteria; 2) employed the SOC task; 3) included a healthy control group; and 4) published in English. We identified 11 studies that employed the SOC task. Results show that people with psychosis have significantly faster initial thinking times than non-clinical participants, but significantly slower subsequent thinking times during problem execution. These findings indicate that differences in processing speed are not limited to slower responses in people with psychosis but may reflect a preference for step-by-step processing rather than planning before task execution. We suggest this style of responding is adopted to compensate for working memory impairment