Effects of the Maryland hydraulic clam dredge on populations of the soft-shell clam, Mya arenaria: final contract report

Final report on a three year study designed to investigate the effects of the Maryland hydraulic escalator clam dredge on populations and recruitment of the soft-shell clam, Mya arenaria. Experimental plots were established in the Potomac river, Maryland, and were dredged ina commerical manner by removing only legal size clams. quarterly samples were taken in the experimental and control plots by means of a van Veen grab for juvenile clams and the hydraulic dredge for older, deeper burrowing clams. Sediment samples were taken at selected periods for organic carbon and grain size analysis. Clams were separated into two size-groups. (PDF contains 38 pages)

Angular distribution and conversion of multi-keV L-shell X-ray sources produced from nanosecond laser irradiated thick-foil targets

An experimental study on the angular distribution and conversion of multi-keV X-ray sources produced from 2 ns-duration 527nm laser irradiated thick-foil targets on Shenguang II laser facility (SG-II) is reported. The angular distributions measured in front of the targets can be fitted with the function of f(theta) = alpha+ (1- alpha)cos(beta) theta (theta is the viewing angle relative to the target normal), where alpha = 0.41 +/- 0.014, beta = 0.77 +/- 0.04 for Ti K-shell X-ray Sources (similar to 4.75 keV for Ti K-shell), and alpha = 0.085 +/- 0.06, beta = 0.59 +/- 0.07 for Ag/Pd/Mo L-shell X-ray Sources (2-2.8 keV for Mo L-shell, 2.8-3.5 keV for Pd L-shell, and 3-3.8 keV for Ag L-shell). The isotropy of the angular-distribution of L-shell emission is worse than that of the K-shell emission at larger viewing angle (>70 degrees), due to its larger optical depth (stronger self-absorption) in the cold plasma side lobe Surrounding the central emission region, and in the central hot plasma region (emission region). There is no observable difference in the angular distributions of the L-shell X-ray emission among Ag, Pd, and Mo. The conversion efficiency of Ag/Pd/Mo L-shell X-ray sources is higher than that of the Ti K-shell X-ray sources, but the gain relative to the K-shell emission is not as high as that by using short pulse lasers. The conversion efficiency of the L-shell X-ray sources decrease, with increasing atomic numbers (or X-ray photon energy), similar to the behavior of the K-shell X-ray Source.

Multilayer Active Shell Mirrors

This thesis presents a novel active mirror technology based on carbon fiber composites and replication manufacturing processes. Multiple additional layers are implemented into the structure in order to provide the reflective layer, actuation capabilities and electrode routing. The mirror is thin, lightweight, and has large actuation capabilities. These features, along with the associated manufacturing processes, represent a significant change in design compared to traditional optics. Structural redundancy in the form of added material or support structures is replaced by thin, unsupported lightweight substrates with large actuation capabilities.

Several studies motivated by the desire to improve as-manufactured figure quality are performed. Firstly, imperfections in thin CFRP laminates and their effect on post-cure shape errors are studied. Numerical models are developed and compared to experimental measurements on flat laminates. Techniques to mitigate figure errors for thicker laminates are also identified. A method of properly integrating the reflective facesheet onto the front surface of the CFRP substrate is also presented. Finally, the effect of bonding multiple initially flat active plates to the backside of a curved CFRP substrate is studied. Figure deformations along with local surface defects are predicted and characterized experimentally. By understanding the mechanics behind these processes, significant improvements to the overall figure quality have been made.

Studies related to the actuation response of the mirror are also performed. The active properties of two materials are characterized and compared. Optimal active layer thicknesses for thin surface-parallel schemes are determined. Finite element simulations are used to make predictions on shape correction capabilities, demonstrating high correctabiliity and stroke over low-order modes. The effect of actuator saturation is studied and shown to significantly degrade shape correction performance.

The initial figure as well as actuation capabilities of a fully-integrated active mirror prototype are characterized experimentally using a Projected Hartmann test. A description of the test apparatus is presented along with two verification measurements. The apparatus is shown to accurately capture both high-amplitude low spatial-frequency figure errors as well as those at lower amplitudes but higher spatial frequencies. A closed-loop figure correction is performed, reducing figure errors by 94%.

Preparação de nanopartículas funcionalizadas do tipo casca-núcleo à base de poliestireno e poli(acrilato de butila) para processamento baroplástico

Copolímeros casca-núcleo de poli(acrilato de butila) (núcleo) e poliestireno (casca) foram sintetizados por meio de polimerização em emulsão, conduzida em duas etapas. A adição de ácido itacônico como monômero funcional na polimerização do núcleo foi realizada para verificar seu efeito sobre suas propriedades mecânicas e de processamento. Os copolímeros foram caracterizados por espalhamento dinâmico de luz (DLS), microscopia eletrônica de transmissão (MET), cromatografia de exclusão por tamanho (SEC), espectrometria na região do infravermelho (FTIR) e calorimetria diferencial por varredura (DSC). A incorporação do monômero funcional foi confirmada por DSC e quantificada por titulação. A proporção de poli(acrilato de butila) e poliestireno influenciou diretamente o processamento e as propriedades mecânicas do polímero. Os copolímeros com teores de poliestireno acima de 50% foram processados por compressão e extrusão a temperatura ambiente, apresentando comportamento baroplástico. A presença do monômero funcional não alterou o processamento do polímero e melhorou significativamente sua resistência à tração, aumentando sua tenacidade

O sistema de controle gerencial em empresas petrolíferas: um estudo de caso múltiplo: os casos da Petróleo Brasileiro S/A. (Petrobras) e da Shell Brasil Ltda

A partir da metade do século passado, a industrialização no Brasil entrou numa fase de grande expansão gerando um aumento na demanda por combustíveis. Neste contexto, a indústria petrolífera tomou um grau de importância espetacular que continua até hoje. O desempenho das empresas ligadas a cadeia de valor de combustíveis passaram a ser importantes para toda a economia, quer pela influência nos custos, como no mercado de capitais, pelos grandes investimentos que requerem. O presente estudo visa analisar os sistemas de controle gerencial das empresas Petróleo Brasileiro S/A (Petrobras) e Shell Brasil Ltda. Tendo como objetivo verificar se os seus sistemas de controle gerenciais estão aderentes a literatura sobre esse tema. A pesquisa de estudo de caso múltiplo foi executada através de entrevista com gerentes das duas petrolíferas sobre objetivos organizacionais, contabilidade por responsabilidade, processo orçamentário, balanced scorecard (BSC) e Enterprise Resource Planning (ERP). Também foram coletadas informações institucionais publicadas pelas duas empresas.

The Maryland soft shell clam industry and its effects on Tidewater resources

This report to the Maryland General Assembly covers: design and operation of the hydraulic clam dredge; summary of knowledge of Maryland's soft shell clam resource; development and present status; Potential value of the resource; Effects of the hydraulic clam dredge; evaluation of the effects of certain proposals concerning the soft shell clam industry; summary.

The relationship of shell dimensions and shell volume to live weight and soft tissue weight in the mangrove clam, Polymesoda erosa (Solander, 1786) from northern Australia

Shell dimensions (length, height, width) and shell volume were evaluated as estimators of growth for Polymesoda erosa in northern Australia. Each parameter was a good estimator when applied to live weight (r2 values of 76-96 percent), but not to soft tissue weight (wet, dry, or ash-free dry weight) (r2 values of 13-32 percent). The b value for shell volume to weight relationship of clams collected during the dry season (June to October) was signifi cantly different than for those collected in the wet season (February to April).

John Nathan Cobb (1868–1930): Founding Director of the College of Fisheries, University of Washington, Seattle

John Nathan Cobb (1868–1930) became the founding Director of the College of Fisheries, University of Washington, Seattle, in 1919 without the benefit of a college education. An inquisitive and ambitious man, he began his career in the newspaper business and was introduced to commercial fisheries when he joined the U.S. Fish Commission (USFC) in 1895 as a clerk, and he was soon promoted to a “Field Agent” in the Division of Statistics, Washington, D.C. During the next 17 years, Cobb surveyed commercial fisheries from Maine to Florida, Hawaii, the Pacific Northwest, and Alaska for the USFC and its successor, the U.S. Bureau of Fisheries. In 1913, he became editor of the prominent west coast trade magazine, Pacific Fisherman, of Seattle, Wash., where he became known as a leading expert on the fisheries of the Pacific Northwest. He soon joined the campaign, led by his employer, to establish the nation’s first fisheries school at the University of Washington. After a brief interlude (1917–1918) with the Alaska Packers Association in San Francisco, Calif., he was chosen as the School’s founding director in 1919. Reflecting his experience and mindset, as well as the University’s apparent initial desire, Cobb established the College of Fisheries primarily as a training ground for those interested in applied aspects of the commercial fishing industry. Cobb attracted sufficient students, was a vigorous spokesman for the College, and had ambitions plans for expansion of the school’s faculty and facilities. He became aware that the College was not held in high esteem by his faculty colleagues or by the University administration because of the school’s failure to emphasize scholastic achievement, and he attempted to correct this deficiency. Cobb became ill with heart problems in 1929 and died on 13 January 1930. The University soon thereafter dissolved the College and dismissed all but one of its faculty. A Department of Fisheries, in the College of Science, was then established in 1930 and was led by William Francis Thompson (1888–1965), who emphasized basic science and fishery biology. The latter format continues to the present in the Department’s successor, The School of Aquatic Fisheries and Science.