Study of high voltage solar array configurations with integrated power control electronics

Solar array electrical configurations for voltage regulatio

Multi-kilowatt modularized spacecraft power processing system development

A review of existing information pertaining to spacecraft power processing systems and equipment was accomplished with a view towards applicability to the modularization of multi-kilowatt power processors. Power requirements for future spacecraft were determined from the NASA mission model-shuttle systems payload data study which provided the limits for modular power equipment capabilities. Three power processing systems were compared to evaluation criteria to select the system best suited for modularity. The shunt regulated direct energy transfer system was selected by this analysis for a conceptual design effort which produced equipment specifications, schematics, envelope drawings, and power module configurations

Entanglement Cost of Antisymmetric States and Additivity of Capacity of Some Quantum Channel

We study the entanglement cost of the states in the contragredient space, which consists of $(d-1)$ $d$-dimensional systems. The cost is always $\log_2 (d-1)$ ebits when the state is divided into bipartite \C^d \otimes (\C^d)^{d-2}. Combined with the arguments in \cite{Matsumoto02}, additivity of channel capacity of some quantum channels is also shown.Comment: revtex 4 pages, no figures, small changes in title and author's affiliation and some typo are correcte

Stating the obvious: evaluating the state of public assurance in fire and rescue authorities in England

Purpose: To examine the form, content and reporting arrangements of 'statements of assurance' required from Fire and Rescue Authorities in England since their introduction in 2012 and identify potential improvements for future implementation. Design/methodology/approach: A multi-method approach was adopted which commenced with an analysis of the current official guidance, an exploration of the accessibility and structure of the current statements produced followed by a review of those statements through a desk based analysis complemented by a series of elite interviews. Findings: The current guidance was found to be too broad and open to interpretation to be fit for purpose. This has led to some significant inconsistencies in reporting, limiting the statements' usefulness to key users and stakeholders. Most authorities provided some form of report on their website but variations in respect of length, structure, name and content, limit their value. The research found that 30% of authorities did not have an up to date statement available online. These findings were supported by the series of interviews. The result has led to confusion amongst authorities as to the statement's role and the risk of it being perceived as a 'box ticking' exercise rather than a real contribution to public assurance. Practical implications: This paper provides potential lessons which could be adopted to inform future guidance in respect of the preparation and publication of the statement of assurance and its role in the wider public assurance regime for fire and rescue authorities. If adopted, these would improve the accountability, transparency and public assurance of Fire and Rescue Authorities which is a key objective of their governance arrangements. Originality/value: The statement of assurance has only been a requirement of Authorities since the current National Framework for Fire and Rescue was published in July 2012 and has not been subject to independent research since its inception. The government have recently issued a consultation on a new national framework, but this proposes no changes to the statements of assurance. The findings will therefore be of value to the government, the Fire and Rescue Sector and the recently appointed regulators for the service Her Majesty's Inspectorate of Constabulary and Fire and Rescue Services (HMICFRS)

Entanglement Cost of Three-Level Antisymmetric States

We show that the entanglement cost of the three-dimensional antisymmetric states is one ebit.Comment: 8page

High-Frequency Spin Waves in YBa2Cu3O6.15

Pulsed neutron spectroscopy is used to make absolute measurements of the dynamic magnetic susceptibility of insulating YBa2Cu3O6.15. Acoustic and optical modes, derived from in- and out-of-phase oscillation of spins in adjacent CuO2 planes, dominate the spectra and are observed up to 250 meV. The optical modes appear first at 74 meV. Linear-spin-wave theory gives an excellent description of the data and yields intra- and inter-layer exchange constants of J_parallel =125 meV and J_perp = 11 meV respectively and a spin-wave intensity renormalization Z_chi = 0.4.Comment: postscript, 11 pages, 4 figures, Fig.2 fixe

Entanglement transmission and generation under channel uncertainty: Universal quantum channel coding

We determine the optimal rates of universal quantum codes for entanglement transmission and generation under channel uncertainty. In the simplest scenario the sender and receiver are provided merely with the information that the channel they use belongs to a given set of channels, so that they are forced to use quantum codes that are reliable for the whole set of channels. This is precisely the quantum analog of the compound channel coding problem. We determine the entanglement transmission and entanglement-generating capacities of compound quantum channels and show that they are equal. Moreover, we investigate two variants of that basic scenario, namely the cases of informed decoder or informed encoder, and derive corresponding capacity results.Comment: 45 pages, no figures. Section 6.2 rewritten due to an error in equation (72) of the old version. Added table of contents, added section 'Conclusions and further remarks'. Accepted for publication in 'Communications in Mathematical Physics

Electron and ion stagnation at the collision front between two laser produced plasmas

We report results from a combined optical interferometric and spectrally resolved imaging study on colliding laser produced aluminium plasmas. A Nomarski interferometer was used to probe the spatio-temporal distribution of electron densities at the collision front. Analysis of the resulting interferograms reveals the formation and evolution of a localized electron density feature with a well-defined profile reminiscent of a stagnation layer. Electron stagnation begins at a time delay of 10 ns after the peak of the plasma generating laser pulse. The peak electron density was found to exceed 10^19 cm^−3 and the layer remained well defined up to a time delay of ca 100 ns. Temporally and spectrally resolved optical imaging was also undertaken, to compare the Al^+ ion distribution with that of the 2D electron density profile. This revealed nascent stagnation of singly charged ions at a delay time of 20 ns. We attribute these results to the effects of space charge separation in the seed plasma plumes

Accessibility of physical states and non-uniqueness of entanglement measure

Ordering physical states is the key to quantifying some physical property of the states uniquely. Bipartite pure entangled states are totally ordered under local operations and classical communication (LOCC) in the asymptotic limit and uniquely quantified by the well-known entropy of entanglement. However, we show that mixed entangled states are partially ordered under LOCC even in the asymptotic limit. Therefore, non-uniqueness of entanglement measure is understood on the basis of an operational notion of asymptotic convertibility.Comment: 8 pages, 1 figure. v2: main result unchanged but presentation extensively changed. v3: figure added, minor correction