WAVE INTERACTION OF THE H-TYPE FLOATING BREAKWATER

Suppression of wave energy has been a challenge to many coastal engineers and researchers. Numerous efforts have been taken in the development of both hard and soft strategies in protecting coastal infrastructures from the intrusion of destructive waves. Breakwater is one of the most widely used structures in offering some degree of protection to the shoreline. Despite excellent wave dampening ability, the fixed breakwaters may pose several drawbacks mostly to the environment, i.e. interruption to sediment transport, interference to fish migration, water pollution and the downcoast erosions. This study aims at developing the H-type floating breakwater in providing an alternative to the bottom-seated breakwaters. A large scale (1:5) test model constructed using plywood and fiberglass coating was extensively tested in a 25-m wave flume equipped with measuring wave probes in its vicinity. Regular and random wave conditions were generated by the wave generator in the flume. Some of the important test parameters were breakwater immersion depth, wave period and wave height. In total, 108 tests were conducted in this study. The hydraulic performance of the H-type floating breakwater was quantified by the coefficients of transmission, reflection and energy loss. In general, the test model is an effective wave attenuator (with wave attenuation up to 95%), strong wave reflector (reflection of 42 - 87% of incident waves) and good energy dissipater (as high as 85%). In comparison with other types of floating breakwater, the H-type floating breakwater outperforms the others in terms of wave attenuation. This indicates that the configuration of the H-shape floating breakwater is effective in enhancing its overall hydraulic performance

An infiltration/cure model for manufacture of fabric composites by the resin infusion process

A 1-D infiltration/cure model was developed to simulate fabrication of advanced textile composites by the resin film infusion process. The simulation model relates the applied temperature and pressure processing cycles, along with the experimentally measured compaction and permeability characteristics of the fabric preforms, to the temperature distribution, the resin degree of cure and viscosity, and the infiltration flow front position as a function of time. The model also predicts the final panel thickness, fiber volume fraction, and resin mass for full saturation as a function of compaction pressure. Composite panels were fabricated using the RTM (Resin Transfer Molding) film infusion technique from knitted, knitted/stitched, and 2-D woven carbon preforms and Hercules 3501-6 resin. Fabric composites were fabricated at different compaction pressures and temperature cycles to determine the effects of the processing on the properties. The composites were C-scanned and micrographed to determine the quality of each panel. Advanced cure cycles, developed from the RTM simulation model, were used to reduce the total cure cycle times by a factor of 3 and the total infiltration times by a factor of 2

Resin transfer molding of textile preforms for aircraft structural applications

The NASA LaRC is conducting and supporting research to develop cost-effective fabrication methods that are applicable to primary composite aircraft structures. One of the most promising fabrication methods that has evolved is resin transfer molding (RTM) of dry textile material forms. RTM has been used for many years for secondary structures, but has received increased emphasis because it is an excellent method for applying resin to damage-tolerant textile preforms at low cost. Textile preforms based on processes such as weaving, braiding, knitting, stitching, and combinations of these have been shown to offer significant improvements in damage tolerance compared to laminated tape composites. The use of low-cost resins combined with textile preforms could provide a major breakthrough in achieving cost-effective composite aircraft structures. RTM uses resin in its lowest cost form, and storage and spoilage costs are minimal. Near net shape textile preforms are expected to be cost-effective because automated machines can be used to produce the preforms, post-cure operations such as machining and fastening are minimized, and material scrap rate may be reduced in comparison with traditional prepreg molding. The purpose of this paper is to discuss experimental and analytical techniques that are under development at NASA Langley to aid the engineer in developing RTM processes for airframe structural elements. Included are experimental techniques to characterize preform and resin behavior and analytical methods that were developed to predict resin flow and cure kinetics

Associations between pre-pregnancy obesity and asthma symptoms in adolescents

Background: The high prevalence of children's asthma symptoms, worldwide, is unexplained. We examined the relation between maternal pre-pregnancy weight and body mass index (BMI), and asthma symptoms in adolescents. Methods: Data from 6945 adolescents born within the Northern Finland Birth Cohort 1986 were used. Prospective antenatal and birth outcome data, including maternal pre-pregnancy weight and BMI, and asthma symptoms in adolescent offspring at age 15–16 years, were employed. Logistic regression analyses were performed to examine the associations between relevant prenatal factors and asthma symptoms during adolescence. Results: Current wheeze (within the past year) was reported by 10.6% of adolescents, and physician-diagnosed asthma by 6.0%. High maternal pre-pregnancy BMI was a significant predictor of wheeze in the adolescents (increase per kilogram per square metre unit; 2.7%, 95% CI 0.9 to 4.4 for ever wheeze; 3.5%, 95% CI 1.3 to 5.8 for current wheeze), and adjusting for potential confounders further increased the risk (2.8%, 95% CI 0.5 to 5.1; 4.7%, 95% CI 1.9 to 7.7, respectively). High maternal pre-pregnancy weight, in the top tertile, also significantly increased the odds of current wheeze in the adolescent by 20% (95% CI 4 to 39), and adjusting for potential confounders further increased the risk (OR=1.52, 95% CI 1.19 to 1.95). Results were similar for current asthma. Furthermore, these significant associations were observed only among adolescents without parental history of atopy but not among those with parental history of atopy. Conclusions: The association demonstrated here between maternal pre-pregnancy overweight and obesity, and asthma symptoms in adolescents suggests that increase in asthma may be partly related to the rapid rise in obesity in recent years

Pathogenesis of experimental bovine spongiform encephalopathy (BSE): estimation of tissue infectivity according to incubation period§

This paper reports the results of tissue infectivity assays of bovine spongiform encephalopathy (BSE) agent in orally exposed cattle at stages during the incubation period. Estimations of the titre of infectivity in central nervous system (CNS), certain peripheral nerve ganglia and distal ileum tissue were made according to time post exposure from the relationship between incubation period and dose for RIII mice and C57bl mice using data from titrations of brain material from cases of BSE. The rate of increase of infectivity in the bovine CNS was then estimated, taking into account these tissue infectivity titres, the variability of the brain titre of clinical field cases of BSE, and the probability density of the expected number of months before clinical onset of each infected bovine. The doubling time for CNS was shown to equal 1.2 months. The titre in the thoracic dorsal root ganglia (DRG) was, on average, approximately 1 log units less than CNS, and cervical DRG approximately 0.5 log less than thoracic DRG. The pattern of increase of infectivity in the distal ileum is that of an initial increase up to 14–18 months post exposure, followed by a decrease, which is likely to be highly variable between animals. These results will be informative for future risk assessments of BSE, especially in relation to reviewing current control measures

Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter

We report new observations with the Very Large Array, Atacama Large Millimeter Array, and Submillimeter Array at frequencies from 1.0 to 355 GHz of the Galactic Center black hole, Sagittarius A*. These observations were conducted between October 2012 and November 2014. While we see variability over the whole spectrum with an amplitude as large as a factor of 2 at millimeter wavelengths, we find no evidence for a change in the mean flux density or spectrum of Sgr A* that can be attributed to interaction with the G2 source. The absence of a bow shock at low frequencies is consistent with a cross-sectional area for G2 that is less than $2 \times 10^{29}$ cm$^2$. This result fits with several model predictions including a magnetically arrested cloud, a pressure-confined stellar wind, and a stellar photosphere of a binary merger. There is no evidence for enhanced accretion onto the black hole driving greater jet and/or accretion flow emission. Finally, we measure the millimeter wavelength spectral index of Sgr A* to be flat; combined with previous measurements, this suggests that there is no spectral break between 230 and 690 GHz. The emission region is thus likely in a transition between optically thick and thin at these frequencies and requires a mix of lepton distributions with varying temperatures consistent with stratification.Comment: Accepted for publication in Ap

NASA Glenn Research Center Program in High Power Density Motors for Aeropropulsion

Electric drive of transport-sized aircraft propulsors, with electric power generated by fuel cells or turbo-generators, will require electric motors with much higher power density than conventional room-temperature machines. Cryogenic cooling of the motor windings by the liquid hydrogen fuel offers a possible solution, enabling motors with higher power density than turbine engines. Some context on weights of various systems, which is required to assess the problem, is presented. This context includes a survey of turbine engine weights over a considerable size range, a correlation of gear box weights and some examples of conventional and advanced electric motor weights. The NASA Glenn Research Center program for high power density motors is outlined and some technical results to date are presented. These results include current densities of 5,000 A per square centimeter current density achieved in cryogenic coils, finite element predictions compared to measurements of torque production in a switched reluctance motor, and initial tests of a cryogenic switched reluctance motor

SISTEMA DE INFORMAÇÃO GEOGRÁFICA COMO FERRAMENTA AUXILIAR NO PROCESSO DE GESTÃO DAS UNIVERSIDADES

A coleta de informações sobre fenômenos que possuem distribuição geográfica é importante, pois permite localizar pontos dentro de um determinado espaço e fazer análises localizacionais. A utilização deste tipo de informação tem sido amplamente utilizada para auxiliar no planejamento de tomada de decisões de diversas empresas, e mais recentemente vem sendo adotada por alguns órgãos da gestão pública, devido a sua eficiência. Este trabalho tem como objetivo criar um Sistema de Informação Geográfica (SIG) do Campus da UFES, localizado em Alegre/ES, afim de que o mesmo sirva como ferramenta de gestão para tomada de decisões. O trabalho será iniciado com o levantamento de dados qualitativos, destacando as principais características de cada edificação construída e sua ocupação no tempo, em seguida serão utilizadas técnicas de pesquisa bibliográfica e documental a fim de respaldar as discussões sobre o tema proposto. Por fim, será elaborado um banco de dados em SIG com todas as informações relativas ao local. A área de estudo compreende o campus da Universidade Federal do Espírito Santo UFES, localizado em Alegre -ES, que foi contemplado pelos planos de extensão do governo e teve sua área construída aumentada no período de 2004 a 2014. A falta de um planejamento adequado na localização dessas obras causa diversos problemas ao campus, como falta de vagas nos estacionamentos, salas de aulas em quantidade e tamanhos insuficientes, áreas verdes de pequenas proporções, dentre outros. A confecção do banco de dados espacial, produto final que se pretende alcançar com esse projeto de dissertação, permitirá minimizar futuros impactos a partir das decisões conscientes da gestão. A proposta enquadra-se na linha de pesquisa Gestão de Operações do Setor Público, na qual a orientadora deste trabalho está alocada. Palavras-chave: banco de dados geográfico; gestão universitária; mapeamento; universidades federais; programas de expansão universitária