Methodology of measuring internal contamination in spacecraft hardware Final report

Methodology of measuring internal contamination in spacecraft hardwar

Magnetic excitations in vanadium spinels

We study magnetic excitations in vanadium spinel oxides AV$_2$O$_4$ (A=Zn, Mg, Cd) using two models: first one is a superexchange model for vanadium S=1 spins, second one includes in addition spin-orbit coupling, and crystal anisotropy. We show that the experimentally observed magnetic ordering can be obtained in both models, however the orbital ordering is different with and without spin-orbit coupling and crystal anisotropy. We demonstrate that this difference strongly affects the spin-wave excitation spectrum above the magnetically ordered state, and argue that the neutron measurement of such dispersion is a way to distinguish between the two possible orbital orderings in AV$_2$O$_4$.Comment: accepted in Phys. Rev.

A Completely Invariant SUSY Transform of Supersymmetric QED

We study the SUSY breaking of the covariant gauge-fixing term in SUSY QED and observe that this corresponds to a breaking of the Lorentz gauge condition by SUSY. Reasoning by analogy with SUSY's violation of the Wess-Zumino gauge, we argue that the SUSY transformation, already modified to preserve Wess-Zumino gauge, should be further modified by another gauge transformation which restores the Lorentz gauge condition. We derive this modification and use the resulting transformation to derive a Ward identitiy relating the photon and photino propagators without using ghost fields. Our transformation also fulfills the SUSY algebra, modulo terms that vanish in Lorentz gauge

Study and modification of the reactivity of carbon fibers

The reactivity to air of polyactylonitrile-based carbon fiber cloth was enhanced by the addition of metals to the cloth. The cloth was oxidized in 54 wt% nitric acid in order to increase the surface area of the cloth and to add carbonyl groups to the surface. Metal addition was then achieved by soaking the cloth in metal acetate solution to effect exchange between the metal carbon and hydrogen on the carbonyl groups. The addition of potassium, sodium, calcium and barium enhanced fiber cloth reactivity to air at 573 K. Extended studies using potassium addition showed that success in enhancing fiber cloth reactivity to air depends on: extent of cloth oxidation in nitric acid, time of exchange in potassium acetate solution and the thoroughness of removing metal acetate from the fiber pore structure following exchange. Cloth reactivity increases essentially linearly with increase in potassium addition via exchange

QAA subject benchmark statement architecture : version for consultation December 2019

The Statement is intended to guide lecturers and course leaders in the design of academic courses leading to qualifications in architecture, it will also be useful to those developing other related courses. Higher education providers may need to consider other reference points in addition to this Statement in designing, delivering and reviewing courses. These may include requirements set out by the Architects Registration Board (ARB), the Royal Institute of British Architects (RIBA) and the Institute for Apprenticeships and Technical Education (IfATE). Providers may also need to consider industry or employer expectations. Individual higher education providers will decide how they use this information. The broad subject of architecture is both academic and vocational. The bachelor's award for architecture is the first stage of the typical education of an architect. This is typically either a BSc or a BA degree. The second stage of academic qualification is a master's level degree, typically in the form of a two-year MArch, which is defined as an undergraduate master's award. Architecture qualifications typically require a total of 360 (Credit Accumulation and Transfer Scheme, or CATS) credits at bachelor's level and 240 (CATS) credits within a master's level degree. While this may equate to five years of 120 (CATS) credits each, higher education providers may construct alternatives to enable flexibility in student learning. This Statement seeks to encapsulate the nature of a rich and diverse academic discipline. It is not intended to prescribe a curriculum, but rather describes the broad intellectual territory within which individual higher education providers will locate their courses of study in architecture

Ocean Thermal Energy Conversion: The Codification of a Potential Technology

Rapid technological advancement has been the hallmark of post-industrial societies for more than a quarter of a century. This progress is forever disrupting our established legal systems. Nowhere is this tension more evident than in the discoveries of the developing energy industry. An exception to this process is the infant industry of ocean thermal energy conversion (OTEC). The United States Congress recently enacted legislation establishing the legal framework for the OTEC process, which has not yet been proven on a commercial scale. OTEC is a form of solar energy that takes advantage of the vertical temperature differentials in those regions of the ocean generally between twenty degrees North latitude and twenty degrees South latitude. An OTEC system consists of a power plant, a floating platforms to house the plant, a surface-level seawater system, a deep water seawater system, and a method of transmitting or utilizing the energy produced. Warm surface water is pumped into a heat exchanger to vaporize a working fluid. A turbo-generator converts the resulting vapor\u27s thermal energy into mechanical and then electrical energy. The vapor leaving the turbine flows into a condenser where it is cooled by cold water pumped up from the deep ocean through a long pipe descending as much as 700 meters or deeper. Although commercial facilities are not expected to be available prior to the late 1980\u27s, two types of OTEC systems are presently under consideration. The closed cycle system6 is closer to commercial realization. In this system, heat derived from surface waters evaporates a working fluid such as ammonia and forces the resulting vapor through a turbine. The turbine powers a generator to create electricity. The vapor returns to liquid form after being chilled with cold water from the ocean depths. The second system is the open cycle system. In this process, warm surface seawater is evaporated in a vacuum. The resulting steam powers a turbine and is then condensed with cold seawater drawn from the ocean depths. OTEC has the potential to fulfill the energy needs of oil-dependent communities. Because OTEC\u27s energy source is solar, it is renewable. Unlike other solar technologies, however, OTEC can operate twenty-four hours a day, year-round due to the ocean\u27s immense solar-collection properties. Yet OTEC will be used for much more than electrical power generation. It has the potential for ammonia production, which presently requires nearly three percent of the total United States output of natural gas. OTEC can be used to process and refine minerals and produce other energy-intensive products such as aluminum. OTEC power can be used to produce fuel for fuel cells that can be transported and used for electricity elsewhere. Considering all these potential uses, OTEC will be a promising area of renewable energy technology if it evolves in a cost-effective and environmentally acceptable manner

A Reconceptualization of the Self-In-Relationship: Contributions from Voices of Cherokee Americans

In any worldview the Self is a central concept. This article summarizes doctoral dissertation research that re-centers a Cherokee American conceptualization of the Self-In-Relationship. In conversational format, the summary details study results that show how a concept analysis methodology plumbs a depth of meaning that a dictionary definition cannot reach in grasping the complex intersection between two meta-worldviews, American Indian and Western. Concepts that emerged about the Self or Self-In-Relationship were held in focus by the Internal Family Systems (IFS) model lens. The conceptualization of Self in the IFS model was found to be resonant with Cherokee American study participants’ narratives and with Cherokee literature about the Self-In-Relationship. Findings from Cherokee descendants’ perspectives may contribute to widening a crosswalk of understanding for those who straddle Cherokee and Western worldviews. Metaphors that emerged from bringing voices from traditional Cherokee knowledge systems into side-by-side interrelationship with voices from Western scholarship re-centered Cherokee conceptual frameworks as foundational for wellbeing and with potential to inform consciousness about healing beyond the sphere of Cherokee culture

Phytoplankton blooms in the Ross Sea, Antarctica: Interannual variability in magnitude, temporal patterns, and composition

The continental shelf of the Ross Sea, Antarctica, is a unique region within the Southern Ocean. Phytoplankton growth is believed to be seasonally limited, first in austral spring by irradiance, and then in summer by biologically available iron. It also is historically known to have taxonomically distinct regimes: the south-central portion is dominated by Phaeocystis antarctica and to the west diatoms are abundant. We measured photochemical yield to interpret the health of the phytoplankton assemblage from 2001-2004 and interfaced these measurements with satellite remote sensing of pigments. The bloom of 2001-2002 was similar in both temporal and spatial distributions to the climatological mean of the Ross Sea, with a peak in biomass being observed in mid-December within the Ross Sea polynyas; F-v/F-m values averaged 0.43. We found high ( 0.50-0.65) F-v/F-m for most of the seasonal phytoplankton bloom for 2002-2003, suggesting that it was not seasonally iron limited. An unusual, large bloom occurred during 2003-2004, with an initial bloom of P. antarctica during austral spring followed by an extensive diatom bloom in summer that may have been enhanced by an intrusion of modified circumpolar deep water. On the basis of an analysis of the historical SeaWiFS records, accumulation of phytoplankton biomass in February may occur approximately every 2-4 years, potentially being a significant source of carbon on the continental shelf

Influence, originality and similarity in directed acyclic graphs

We introduce a framework for network analysis based on random walks on directed acyclic graphs where the probability of passing through a given node is the key ingredient. We illustrate its use in evaluating the mutual influence of nodes and discovering seminal papers in a citation network. We further introduce a new similarity metric and test it in a simple personalized recommendation process. This metric's performance is comparable to that of classical similarity metrics, thus further supporting the validity of our framework.Comment: 6 pages, 4 figure