Experimental cold-flow evaluation of a ram air cooled plug nozzle concept for afterburning turbojet engines

A concept for plug nozzles cooled by inlet ram air is presented. Experimental data obtained with a small scale model, 21.59-cm (8.5-in.) diameter, in a static altitude facility demonstrated high thrust performance and excellent pumping characteristics. Tests were made at nozzle pressure ratios simulating supersonic cruise and takeoff conditions. Effect of plug size, outer shroud length, and varying amounts of secondary flow were investigated

Addition of a gamma ray spectrometer to the alpha scattering experiment as designed for the Surveyor mission

Gamma ray spectroscopy and alpha scattering techniques for compositional analysis of lunar and planetary surface

Cold-flow performance of several variations of a ram-air-cooled plug nozzle for supersonic-cruise aircraft

Experimental data were obtained with a 21.59 cm (8.5 in.) diameter cold-flow model in a static altitude facility to determine the thrust and pumping characteristics of several variations of a ram-air-cooled plug nozzle. Tests were conducted over a range of nozzle pressure ratios simulating supersonic cruise and takeoff conditions. Primary throat area was also varied to simulate afterburner on and off. Effect of plug size, outer shroud length, primary nozzle geometry, and varying amounts of secondary flow were investigated. At a supersonic cruise pressure ratio of 27, nozzle efficiencies were 99.7 percent for the best configurations

SU(2) lattice gauge theory at non-zero temperature with fixed holonomy boundary condition

We study SU(2) lattice gauge theory at $T>0$ in a finite box with fixed holonomy value at the spatial boundary. We search for (approximate) classical solutions of the lattice field equations and find in particular the dissociated calorons recently discussed by van Baal and collaborators.Comment: Talk at Lattice 2000, Bangalore; 4 pages, 4 figures, LaTe

Calorons and BPS monopoles with non-trivial holonomy in the confinement phase of SU(2) gluodynamics

With the help of the cooling method applied to SU(2) lattice gauge theory at non-zero $T \le T_c$ we present numerical evidence for the existence of superpositions of Kraan-van Baal caloron (or BPS monopole pair) solutions with non-trivial holonomy, which might constitute an important contribution to the semi-classical approximation of the partition function.Comment: 3 pages, 6 figures, contribution to Lattice2002(topology

Hierarchically-structured metalloprotein composite coatings biofabricated from co-existing condensed liquid phases

Complex hierarchical structure governs emergent properties in biopolymeric materials; yet, the material processing involved remains poorly understood. Here, we investigated the multi-scale structure and composition of the mussel byssus cuticle before, during and after formation to gain insight into the processing of this hard, yet extensible metal cross-linked protein composite. Our findings reveal that the granular substructure crucial to the cuticle’s function as a wear-resistant coating of an extensible polymer fiber is pre-organized in condensed liquid phase secretory vesicles. These are phase-separated into DOPA-rich proto-granules enveloped in a sulfur-rich proto-matrix which fuses during secretion, forming the sub-structure of the cuticle. Metal ions are added subsequently in a site-specific way, with iron contained in the sulfur-rich matrix and vanadium coordinated by DOPA-catechol in the granule. We posit that this hierarchical structure self-organizes via phase separation of specific amphiphilic proteins within secretory vesicles, resulting in a meso-scale structuring that governs cuticle function

The development and evaluation of exercises for group response to word meaning for increasing the speed of word recognition in grade I

Thesis (Ed.M.)--Boston Universit

Price Cutting in Liability Insurance Markets

This article analyzes alleged underpricing of general liability insurance prior to the mid-1980s liability insurance crisis. The theoretical analysis considers whether moral hazard and/or heterogeneous information for forecasting claim costs can cause some firms to price too low and depress other firms\u27 prices. Cross-sectional analysis of insurer loss forecast revisions (which should be greater for firms with low prices caused by moral hazard or hetero- geneous information) and premium growth provides evidence consistent with low pricing due to moral hazard but not heterogeneous information. The evidence also implies that shifts in the loss distribution produced large industrywide forecast errors

Workers’ Compensation Rate Regulation: How Price Controls Increase Costs*

In the 1980s, regulation constrained workers’ compensation insurance premiums in the face of rapid growth in loss costs. We develop and test the hypothesis that rate suppression exacerbates loss growth, leading to higher losses and premiums. The empirical analysis using rating class data for eight states for the period 1985–91 confirms that rate suppression, measured by lagged residual‐market share of payroll, increased loss growth. The cost‐increasing effects are greater in the residual market than in the voluntary market, but premiums increased more rapidly in the voluntary market. The resulting pattern of cross subsidies between and within classes is consistent with a simple model of political influence, with subsidies to high risks and small firms at the expense of low risks and insurer equity

Rapid self-assembly of complex biomolecular architectures during mussel byssus biofabrication

Protein-based biogenic materials provide important inspiration for the development of high-performance polymers. The fibrous mussel byssus, for instance, exhibits exceptional wet adhesion, abrasion resistance, toughness and self-healing capacity–properties that arise from an intricate hierarchical organization formed in minutes from a fluid secretion of over 10 different protein precursors. However, a poor understanding of this dynamic biofabrication process has hindered effective translation of byssus design principles into synthetic materials. Here, we explore mussel byssus assembly in Mytilus edulis using a synergistic combination of histological staining and confocal Raman microspectroscopy, enabling in situ tracking of specific proteins during induced thread formation from soluble precursors to solid fibres. Our findings reveal critical insights into this complex biological manufacturing process, showing that protein precursors spontaneously self-assemble into complex architectures, while maturation proceeds in subsequent regulated steps. Beyond their biological importance, these findings may guide development of advanced materials with biomedical and industrial relevance