Cost analysis of composite fan blade manufacturing processes

The relative manufacturing costs were estimated for large high technology fan blades prepared by advanced composite fabrication methods using seven candidate materials/process systems. These systems were identified as laminated resin matrix composite, filament wound resin matrix composite, superhybrid solid laminate, superhybrid spar/shell, metal matrix composite, metal matrix composite with a spar and shell, and hollow titanium. The costs were calculated utilizing analytical process models and all cost data are presented as normalized relative values where 100 was the cost of a conventionally forged solid titanium fan blade whose geometry corresponded to a size typical of 42 blades per disc. Four costs were calculated for each of the seven candidate systems to relate the variation of cost on blade size. Geometries typical of blade designs at 24, 30, 36 and 42 blades per disc were used. The impact of individual process yield factors on costs was also assessed as well as effects of process parameters, raw materials, labor rates and consumable items

Ammonia and nitric acid concentrations in equilibrium with atmospheric aerosols: Experiment vs theory

The equilibrium between gaseous ammonia, nitric acid, and aerosol nitrate is discussed on the basis of a recent field experiment in southern California. Comparison is drawn between theoretical equilibrium calculations and simultaneous measurements of nitric acid, ammonia, ammonium ion, nitrate ion, sulfate ion, other ionic species, temperature and dewpoint. Particulate and gaseous pollutant concentrations at some inland sampling sites are readily explained if the aerosol is assumed to exist as an external mixture with all particulate nitrate and ammonium available to form pure NH_4NO_3. At other monitoring sites, especially near the coast, aerosol nitrate is found in the presence of NH_3 and HNO_3 concentrations that thermodynamic calculations show are too low to produce pure NH_4NO_3. This can be explained when the amount of aerosol nitrate that can be derived from reaction of nitric acid with sea salt and soil dust is taken into account. A calculation approach that accounts for the presence of mixed sulfate and nitrate salts improves the agreement between predicted and observed pollutant concentrations in the majority of cases studied. Uncertainties in these calculations arise from a number of sources including the thermodynamic quantities, and the effect of these uncertainties on the comparison between theory and experiment is discussed

Cost analysis of advanced turbine blade manufacturing processes

A rigorous analysis was conducted to estimate relative manufacturing costs for high technology gas turbine blades prepared by three candidate materials process systems. The manufacturing costs for the same turbine blade configuration of directionally solidified eutectic alloy, an oxide dispersion strengthened superalloy, and a fiber reinforced superalloy were compared on a relative basis to the costs of the same blade currently in production utilizing the directional solidification process. An analytical process cost model was developed to quantitatively perform the cost comparisons. The impact of individual process yield factors on costs was also assessed as well as effects of process parameters, raw materials, labor rates and consumable items

Social Determinants of Health and What Mothers Say They Need and Want After Release From Jail.

Identifying the biopsychosocial needs of mothers who have been released from jail is critical to understanding the best ways to support their health and stability after release. In May through August 2014, we interviewed 15 mothers who had been released from an urban jail about their reentry experiences, and we analyzed transcripts for themes. Eight domains of community reentry emerged through analysis: behavioral health services, education, employment, housing, material resources, medical care, relationships with children, and social support. Participants defined barriers to successful reentry, which paralleled the social determinants of health, and shared suggestions that could be used to mitigate these barriers

SELF-ASSEMBLED ANISOTROPIC COLLOID SYSTEMS FOR PHOTONIC APPLICATIONS

Photonic crystals are optical structures periodic on the length scale of light, and support useful attributes including photonic bandgaps (ranges of frequencies forbidden from propagating in the material), negative refraction and slow light effects (extremely low group velocity). Such effects have applications in sensors, waveguides, solid-state lighting, photovoltaics and superlenses, among others. The optical characteristics of a photonic crystal are determined by the interplay of structure, order and materials properties in the crystal. Self-assembled anisotropic colloids are attractive templates for photonic crystals due to their cost effectiveness and diversity of structures and symmetries. Introducing entropic and enthalpic effects to engineer inter-particle interactions increases the variety of phases and mesophases in anisotropic colloidal assemblies. In this dissertation, the photonic properties of self-assembly inspired structures are investigated via electromagnetic simulations. New paradigms for self-assembled photonic crystals are developed, and desirable properties such as photonic bandgaps, negative refraction, and slow light are correlated with structural and materials parameters informed by colloidal assemblies. Specifically, the photonic crystal properties of partial order rotator crystals, Archimedean tilings, and quasi-two dimensional ‘slab’ crystalline structures are investigated. All three systems display large photonic bandgaps. Slow light effects are observed in the rotator crystal and Archimedean tilings. As well, negative refractive index is predicted in the ‘slab’ crystal and the Archimedean tiling. These projects open new frontiers for research to manipulate self-assembled systems for photonics. Additionally, the assembly of colloidal C60 platelets is investigated under two-dimensional confinement and electric field. The C60 platelets are synthesized via a co-solvent precipitation method. The particles assemble under dipolar forces, dielectrophoretic forces, and electrohydrodynamic flows. Frequency-dependent phase transitions occur at the critical Maxwell-Wagner crossover frequency, where the effective polarizability of the particles in the medium is substantially reduced. Structures form as a function of field strength, frequency and confinement including hexagonal, oblique, string fluid, coexistent hexagonal-rhombic, and tetratic

Managing Cultural Resources On The Alaska Peninsula

Twentieth-century cultural resources provide physical evidence of human relationships with a landscape that has shaped the wilderness areas we know today. These cultural resources enrich the meaning of an area as wilderness, but also present multiple management challenges surrounding visitor use in designated wilderness areas. The National Geographic Society Katmai Expeditions of the 1910s present a case study of how historic trails and their associated artifacts interact not only with present issues toward the dual-enforcement of the National Historic Preservation Act and Wilderness Act, but also with the management of visitor use along a corridor containing relatively recent traces of historically significant activities and events. This study draws on the findings of a 2 018 expedition identifying convergence of a historically significant trail w ith a popular path for backpackers through the Katmai Wilderness and explores the importance of cultural resources in long-distance trail planning and cultural resource management in designated wilderness

Semi-classical Characters and Optical Model Description of Heavy Ion Scattering, Direct Reactions, and Fusion at Near-barrier Energies

An approach is proposed to calculate the direct reaction (DR) and fusion probabilities for heavy ion collisions at near-Coulomb-barrier energies as functions of the distance of closest approach D within the framework of the optical model that introduces two types of imaginary potentials, DR and fusion. The probabilities are calculated by using partial DR and fusion cross sections, together with the classical relations associated with the Coulomb trajectory. Such an approach makes it possible to analyze the data for angular distributions of the inclusive DR cross section, facilitating the determination of the radius parameters of the imaginary DR potential in a less ambiguous manner. Simultaneous $\chi^{2}$-analyses are performed of relevant data for the $^{16}$O+$^{208}$Pb system near the Coulomb-barrier energy

Acquisition of regional air quality model validation data for nitrate, sulfate, ammonium ion and their precursors

An intensive field study was conducted throughout California's South Coast Air Basin to acquire air quality model validation data for use with aerosol nitrate formation models. Aerosol nitrate, sulfate, ammonium, other major ionic aerosol species, nitric acid gas and ammonia were measured concurrently at ten sites for forty-eight consecutive hours during the period 30–31 August 1982. Ozone, NO and NO_x were measured at all locations, and PAN was measured at Pasadena and Riverside, completing a nitrogen balance on the air masses studied. The product of the measured nitric acid and ammonia concentrations ranged from less than 1 ppbv^2 to greater than 300 ppbv^2 during the experiment, providing a wide range of conditions over which comparisons can be drawn between chemical equilibrium calculations and experimental results. The ionic material in the aerosol phase was chemically more complex than is assumed by present theoretical models for the equilibrium between NH_3, HNO_3 and the aerosol phase, and included significant amounts of Na^+, Ca^(2+), Mg^(2+), K^+ and Cl^− in addition to NH_4^+, SO_4^(2−) and NO_3^−. Results of the experiment showed that aerosol nitrate levels in excess of 20 μm^(−3) accumulated in near-coastal locations in the morning of 31 August, followed by subsequent transport across the air basin. Trajectory analysis showed that the afternoon aerosol nitrate peak observed inland at Rubidoux near Riverside was associated with the same air mass that contained the high morning nitrate levels near the coast, indicating that description of both transport and atmospheric chemical reactions is important in understanding regional nitrate dynamics

Residential mobility in ethnic enclaves in Lawrence, Massachusetts

Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2007.Includes bibliographical references (p. [113]-118).Spatial assimilation theory presents a dilemma for community-based organizations (CBOs) in ethnic enclaves, especially those CBOs that assist enclavers--residents of ethnic enclaves-in building assets such as increased earnings or English fluency. The theory suggests that as immigrants build assets they are more likely to leave ethnic enclaves in search of more amenity-rich neighborhoods. Thus, the very people that could be leaders in community revitalization are also the most apt to leave, interrupting the potential positive benefits they could have on the community by, for example, spending money in community, creating businesses that employ community members, or serving on the local Parent-Teacher Association. To better understand residential mobility in ethnic enclaves in Lawrence, Massachusetts, this thesis analyzes results of a survey of Lawrence enclavers to identify which factors were important to enclavers in choosing a home both when they first moved to Lawrence and now. Further, this thesis identifies factors that Lawrence meets particularly well and factors that leave room for improvement across several points in time.(cont.) Contrary to spatial assimilation theory, the findings of this thesis suggest that as enclavers build assets they are actually more likely to plan to stay in Lawrence because they are able to improve their living conditions within the enclave and still maintain wanted social and cultural connections. This implies that the dilemma Lawrence CBOs face may be less problematic than originally thought. However, this thesis also discovered that there were enclavers that built assets and planned to leave Lawrence. Most likely their mobility decisions stem from dissatisfaction with public schools and neighborhood safety. This thesis recommends that Lawrence CBOs pursue initiatives that seek to improve schools and neighborhood safety while expanding the reach of community-based organizations and empowering enclavers.by Aaron Stelson.M.C.P