Cold Flow Determination of the Internal Flow Environment Around the Submerged TVC Nozzle for the Space Shuttle SRM

A series of subscale cold flow tests was performed to quantify the gas flow characteristics at the aft end of the Space Shuttle Solid Rocket Motor. This information was used to support the analyses of the redesigned nozzle/case joint. A portion of the thermal loads at the joint are due to the circumferential velocities and pressure gradients caused primarily by the gimbaling of the submerged nose TVC nozzle. When the nozzle centerline is vectored with respect to the motor centerline, asymmetries are set up in the flow field under the submerged nozzle and immediately adjacent to the nozzle/case joint. Specific program objectives included: determination of the effects of nozzle gimbal angle and propellant geometry on the circumferential flow field; measurement of the static pressure and gas velocities in the vicinity of the nozzle/case joint; use of scaling laws to apply the subscale cold flow data to the full scale SRM; and generation of data for use in validation of 3-D computational fluid dynamic, CFD, models of the SRM flow field. These tests were conducted in the NASA Marshall Space Flight Center Airflow Facility with a 7.5 percent scale model of the aft segment of the SRM. Static and dynamic pressures were measured in the model to quantify the flow field. Oil flow data was also acquired to obtain qualitative visual descriptions of the flow field. Nozzle gimbal angles of 0, 3.5, and 7 deg were used with propellant grain configurations corresponding to motor burn times of 0, 9, 19, and 114 seconds. This experimental program was successful in generating velocity and pressure gradient data for the flow field around the submerged nose nozzle of the Space Shuttle SRM at various burn times and gimbal angles. The nature of the flow field adjacent to the nozzle/case joint was determined with oil droplet streaks, and the velocity and pressure gradients were quantified with pitot probes and wall static pressure measurements. The data was applied to the full scale SRM thru a scaling analysis and the results compared well with the 3-D computational fluid dynamics computer model

A Neutrosophic Description Logic

Description Logics (DLs) are appropriate, widely used, logics for managing structured knowledge. They allow reasoning about individuals and concepts, i.e. set of individuals with common properties. Typically, DLs are limited to dealing with crisp, well defined concepts. That is, concepts for which the problem whether an individual is an instance of it is yes/no question. More often than not, the concepts encountered in the real world do not have a precisely defined criteria of membership: we may say that an individual is an instance of a concept only to a certain degree, depending on the individual's properties. The DLs that deal with such fuzzy concepts are called fuzzy DLs. In order to deal with fuzzy, incomplete, indeterminate and inconsistent concepts, we need to extend the fuzzy DLs, combining the neutrosophic logic with a classical DL. In particular, concepts become neutrosophic (here neutrosophic means fuzzy, incomplete, indeterminate, and inconsistent), thus reasoning about neutrosophic concepts is supported. We'll define its syntax, its semantics, and describe its properties.Comment: 18 pages. Presented at the IEEE International Conference on Granular Computing, Georgia State University, Atlanta, USA, May 200

'If she gets married when she is young, she will give birth to many kids': a qualitative study of child marriage practices amongst nomadic pastoralist communities in Kenya

Child marriage is associated with adverse health and social outcomes for women and girls. Among pastoralists in Kenya, child marriage is believed to be higher compared to the national average. This paper explores how social norms and contextual factors sustain child marriage in communities living in conflict-affected North Eastern Kenya. In-depth interviews were carried out with nomadic and semi-nomadic women and men of reproductive age in Wajir and Mandera counties. Participants were purposively sampled across a range of age groups and community types. Interviews were analysed thematically and guided by a social norms approach. We found changes in the way young couples meet and evidence for negative perceptions of child marriage due to its impact on the girls’ reproductive health and gender inequality. Despite this, child marriage was common amongst nomadic and semi-nomadic women. Two overarching themes explained child marriage practices: 1) gender norms, and 2) desire for large family size. Our findings complement the global literature, while contributing perspectives of pastoralist groups. Contextual factors of poverty, traditional pastoral lifestyles and limited formal education opportunities for girls, supported large family norms and gender norms that encouraged and sustained child marriage

OperA/ALIVE/OperettA

Comprehensive models for organizations must, on the one hand, be able to specify global goals and requirements but, on the other hand, cannot assume that particular actors will always act according to the needs and expectations of the system design. Concepts as organizational rules (Zambonelli 2002), norms and institutions (Dignum and Dignum 2001; Esteva et al. 2002), and social structures (Parunak and Odell 2002) arise from the idea that the effective engineering of organizations needs high-level, actor-independent concepts and abstractions that explicitly define the organization in which agents live (Zambonelli 2002).Peer ReviewedPostprint (author's final draft

On QBF Proofs and Preprocessing

QBFs (quantified boolean formulas), which are a superset of propositional formulas, provide a canonical representation for PSPACE problems. To overcome the inherent complexity of QBF, significant effort has been invested in developing QBF solvers as well as the underlying proof systems. At the same time, formula preprocessing is crucial for the application of QBF solvers. This paper focuses on a missing link in currently-available technology: How to obtain a certificate (e.g. proof) for a formula that had been preprocessed before it was given to a solver? The paper targets a suite of commonly-used preprocessing techniques and shows how to reconstruct certificates for them. On the negative side, the paper discusses certain limitations of the currently-used proof systems in the light of preprocessing. The presented techniques were implemented and evaluated in the state-of-the-art QBF preprocessor bloqqer.Comment: LPAR 201

Randomisation and Derandomisation in Descriptive Complexity Theory

We study probabilistic complexity classes and questions of derandomisation from a logical point of view. For each logic L we introduce a new logic BPL, bounded error probabilistic L, which is defined from L in a similar way as the complexity class BPP, bounded error probabilistic polynomial time, is defined from PTIME. Our main focus lies on questions of derandomisation, and we prove that there is a query which is definable in BPFO, the probabilistic version of first-order logic, but not in Cinf, finite variable infinitary logic with counting. This implies that many of the standard logics of finite model theory, like transitive closure logic and fixed-point logic, both with and without counting, cannot be derandomised. Similarly, we present a query on ordered structures which is definable in BPFO but not in monadic second-order logic, and a query on additive structures which is definable in BPFO but not in FO. The latter of these queries shows that certain uniform variants of AC0 (bounded-depth polynomial sized circuits) cannot be derandomised. These results are in contrast to the general belief that most standard complexity classes can be derandomised. Finally, we note that BPIFP+C, the probabilistic version of fixed-point logic with counting, captures the complexity class BPP, even on unordered structures

Search reduction in hierarchical distributed problem solving

Knoblock and Korf have determined that abstraction can reduce search at a single agent from exponential to linear complexity (Knoblock 1991; Korf 1987). We extend their results by showing how concurrent problem solving among multiple agents using abstraction can further reduce search to logarithmic complexity. We empirically validate our formal analysis by showing that it correctly predicts performance for the Towers of Hanoi problem (which meets all of the assumptions of the analysis). Furthermore, a powerful form of abstraction for large multiagent systems is to group agents into teams, and teams of agents into larger teams, to form an organizational pyramid. We apply our analysis to such an organization of agents and demonstrate the results in a delivery task domain. Our predictions about abstraction's benefits can also be met in this more realistic domain, even though assumptions made in our analysis are violated. Our analytical results thus hold the promise for explaining in general terms many experimental observations made in specific distributed AI systems, and we demonstrate this ability with examples from prior research.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42828/1/10726_2005_Article_BF01384251.pd

Improving health system readiness to address violence against women and girls: a conceptual framework.

BACKGROUND: There is an increasing focus on readiness of health systems to respond to survivors of violence against women (VAW), a global human rights violation damaging women's health. Health system readiness focuses on how prepared healthcare systems and institutions, including providers and potential users, are to adopt changes brought about by the integration of VAW care into services. In VAW research, such assessment is often limited to individual provider readiness or facility-level factors that need to be strengthened, with less attention to health system dimensions. The paper presents a framework for health system readiness assessment to improve quality of care for intimate partner violence (IPV), which was tested in Brazil and Palestinian territories (oPT). METHODS: Data synthesis of primary data from 43 qualitative interviews with healthcare providers and health managers in Brazil and oPT to explore readiness in health systems. RESULTS: The application of the framework showed that it had significant added value in capturing system capabilities - beyond the availability of material and technical capacity - to encompass stakeholder values, confidence, motivation and connection with clients and communities. Our analysis highlighted two missing elements within the initial framework: client and community engagement and gender equality issues. Subsequently, the framework was finalised and organised around three levels of analysis: macro, meso and micro. The micro level highlighted the need to also consider how the system can sustainably involve and interact with clients (women) and communities to ensure and promote readiness for integrating (and participating in) change. Addressing cultural and gender norms around IPV and enhancing support and commitment from health managers was also shown to be necessary for a health system environment that enables the integration of IPV care. CONCLUSION: The proposed framework helps identify a) system capabilities and pre-conditions for system readiness; b) system changes required for delivering quality care for IPV; and c) connections between and across system levels and capabilities

Event by event analysis of collision induced cluster ion fragmentation: sequential monomer evaporation versus fission reactions

IP