An Analysis of Current Interruption upon the Behavior of Light Bulb Filament during Initial Aircraft Impact in Support of Aircraft Accident Investigations

The purpose of analyzing annunciator panels, warning, and indicator lamps is to determine the state ( on or off ) of each light bulb immediately before the impact. Determination of the state of lamps may help investigators determine the probable cause of the accident. The information gained from the lamp\u27s filaments may be used to infer the aircraft\u27s operational parameters prior to impact and to a qualitative appreciation of the severity of the accident. It is generally agreed that upon impact the filament of an unlit bulb will fracture without deformation and the filament of a lit bulb will display plastic deformation (Ellis, 1984). The main purpose of this study was to investigate the effects of current disruption as a result of initial impact forces upon light bulb filament behavior. One hundred and twenty commercially available T-1 five volt and T-1 twenty-eight volt aircraft light bulbs were subjected to inertial impact deceleration forces up to and including 90 times the force of gravity to investigate the effects of current disruption during the impact sequence. The age of the light bulbs ranged of from 50 to 1,600 hours. An air-cannon was used to accelerate the lamps along its horizontal barrel with impact occurring at a hydro-brake located 13 feet from the beginning of the barrel. The hydro-brake produced an inertial deceleration which neither broke the glass envelope nor destroyed the filament. Severance of power was accomplished through the use of a microswitch and a solid state relay. It was hypothesized that there would be a noticeable combination of ductile and brittle deformation characteristics in the filaments as the result of these deceleration forces. The filament analysis of the #6839 lamps displayed brittle fractures along with a combination of plastic deformations. The #6839 double helix filament displayed stretching, uncoiling, entanglement, and general deformation of its secondary coil with localized areas of stretching and general deformation of its primary coil. The #718 lamps exhibited plastic deformation characteristics typical of a filament at its brittle or off state. The #718 lamps that were aged 1,600 hours displayed plastic deformations typical of a lamp that was illuminated or on prior to impact. The filaments exhibited coil stretching and general deformation. The effects of aging had an important influence upon the behavior of the filaments in both lamp types. The on-set rate of notching depending upon the rated life of the lamp, the filament size, and rated current. Lamps with high rated life rates and low current requirements experienced a slower on-set of notching. Transient indications of the #6839 lamp included a combination of stretching, local, resonance, slight, uncoiling, and general deformations accompanied by brittle fractures. The transient indications of the #718 lamps, aged 200 hours and older, included slight, local, stretching, and general deformations. Aging effects have a major influence upon the deformation behavior of the filament. The lamp\u27s rated life, operating voltage, and filament diameter control the degree and onset of the notching effect which affects the deformation behavior. Based on the results and conclusions obtained from this research, the following recommendations are suggested: (a) the development damage boundary curves for the T-1 series of lamps, (b) the investigation of resonance deformation in the T-1 lamp, and (c) additional testing of the T-1 lamp to better understand the relationship between the onset of notching and the lamp\u27s rated life

Instar behavior of Chaoborus punctipennis Say

Call number: LD2668 .T4 1965 L332Master of Scienc

Observed Versus GCM-Generated Local Tropical Cyclone Frequency: Comparisons Using a Spatial Lattice

Of broad scientific and public interest is the reliability of global climate models (GCMs) to simulate future regional and local tropical cyclone (TC) occurrences. Atmospheric GCMs are now able to generate vortices resembling actual TCs, but questions remain about their fidelity to observed TCs. Here the authors demonstrate a spatial lattice approach for comparing actual with simulated TC occurrences regionally using observed TCs from the International Best Track Archive for Climate Stewardship (IBTrACS) dataset and GCM-generated TCs from the Geophysical Fluid Dynamics Laboratory (GFDL) High Resolution Atmospheric Model (HiRAM) and Florida State University (FSU) Center for Ocean–Atmospheric Prediction Studies (COAPS) model over the common period 1982–2008. Results show that the spatial distribution of TCs generated by the GFDL model compares well with observations globally, although there are areas of over- and underprediction, particularly in parts of the Pacific Ocean. Difference maps using the spatial lattice highlight these discrepancies. Additionally, comparisons focusing on the North Atlantic Ocean basin are made. Results confirm a large area of overprediction by the FSU COAPS model in the south-central portion of the basin. Relevant to projections of future U.S. hurricane activity is the fact that both models underpredict TC activity in the Gulf of Mexico

Sensitivity of Limiting Hurricane Intensity to SST in the Atlantic from Observations and GCMs

Abstract A statistical model for the intensity of the strongest hurricanes has been developed and a new methodology introduced for estimating the sensitivity of the strongest hurricanes to changes in sea surface temperature. Here, the authors use this methodology on observed hurricanes and hurricanes generated from two global climate models (GCMs). Hurricanes over the North Atlantic Ocean during the period 1981–2010 show a sensitivity of 7.9 ± 1.19 m s−1 K−1 (standard error; SE) when over seas warmer than 25°C. In contrast, hurricanes over the same region and period generated from the GFDL High Resolution Atmospheric Model (HiRAM) show a significantly lower sensitivity with the highest at 1.8 ± 0.42 m s−1 K−1 (SE). Similar weaker sensitivity is found using hurricanes generated from the Florida State University Center for Ocean–Atmospheric Prediction Studies (FSU-COAPS) model with the highest at 2.9 ± 2.64 m s−1 K−1 (SE). A statistical refinement of HiRAM-generated hurricane intensities heightens the sensitivity to a maximum of 6.9 ± 3.33 m s−1 K−1 (SE), but the increase is offset by additional uncertainty associated with the refinement. Results suggest that the caution that should be exercised when interpreting GCM scenarios of future hurricane intensity stems from the low sensitivity of limiting GCM-generated hurricane intensity to ocean temperature.</jats:p

Western North Pacific tropical cyclone model tracks in present and future climates

Western North Pacific tropical cyclone (TC) model tracks are analyzed in two large multimodel ensembles, spanning a large variety of models and multiple future climate scenarios. Two methodologies are used to synthesize the properties of TC tracks in this large data set: cluster analysis and mass moment ellipses. First, the models' TC tracks are compared to observed TC tracks' characteristics, and a subset of the models is chosen for analysis, based on the tracks' similarity to observations and sample size. Potential changes in track types in a warming climate are identified by comparing the kernel smoothed probability distributions of various track variables in historical and future scenarios using a Kolmogorov-Smirnov significance test. Two track changes are identified. The first is a statistically significant increase in the north-south expansion, which can also be viewed as a poleward shift, as TC tracks are prevented from expanding equatorward due to the weak Coriolis force near the equator. The second change is an eastward shift in the storm tracks that occur near the central Pacific in one of the multimodel ensembles, indicating a possible increase in the occurrence of storms near Hawaii in a warming climate. The dependence of the results on which model and future scenario are considered emphasizes the necessity of including multiple models and scenarios when considering future changes in TC characteristics

Dynamically and Statistically Downscaled Seasonal Temperature and Precipitation Hindcast Ensembles for the Southeastern USA

We present results from a 15-year 10-member warm season (March–September) hindcast ensemble of maximum and minimum surface air temperatures and precipitation in southeast USA. The hindcasts are derived from the Florida State University/Center for Ocean-Atmospheric Prediction Studies Global Spectral Model (FSU/COAPS GSM) and downscaled using both the FSU/COAPS Nested Regional Spectral Model (NRSM) and a statistical downscaling method based on stochastic weather generator techniques. We additionally consider statistical bias correction of the dynamical model output. Basic descriptive statistics indicate that the bias-corrected and statistically downscaled data reduce the FSU/COAPS GSM bias considerably in terms of basic climatology. Statistics describing the daily precipitation process are improved by both downscaling techniques relative to the bias-corrected GSM. Improvement in monthly and seasonal hindcasts relative to FSU/COAPS GSM is spatially and temporally varying. Precipitation hindcasts are generally less skillful than those for temperature, although useful precipitation predictability exists at many locations. Hindcast improvements due to downscaling are greatest over peninsular Florida. The smallest root mean square errors (RMSE) for temperature hindcasts are found in the southern part of the study region during the spring months of March, April and May (MAM) for maximum surface air temperature, and in the summer, June, July and August (JJA), for minimum surface air temperature. Overall, there is no indication that either downscaling method has a direct advantage over the other

Characteristics of tropical cyclones in high-resolution 1 models in the present climate

The global characteristics of tropical cyclones (TCs) simulated by several climate models are analyzed and compared with observations. The global climate models were forced by the same sea surface temperature (SST) fields in two types of experiments, using climatological SST and interannually varying SST. TC tracks and intensities are derived from each model's output fields by the group who ran that model, using their own preferred tracking scheme; the study considers the combination of model and tracking scheme as a single modeling system, and compares the properties derived from the different systems. Overall, the observed geographic distribution of global TC frequency was reasonably well reproduced. As expected, with the exception of one model, intensities of the simulated TC were lower than in observations, to a degree that varies considerably across modelsPublished1154–11724A. Clima e OceaniJCR Journalrestricte

How Well Do Global Climate Models Simulate the Variability of Atlantic Tropical Cyclones Associated with ENSO?

The variability of Atlantic tropical cyclones (TCs) associated with El Nino-Southern Oscillation (ENSO) in model simulations is assessed and compared with observations. The model experiments are 28-yr simulations forced with the observed sea surface temperature from 1982 to 2009. The simulations were coordinated by the U.S. CLIVAR Hurricane Working Group and conducted with five global climate models (GCMs) with a total of 16 ensemble members. The model performance is evaluated based on both individual model ensemble means and multi-model ensemble mean. The latter has the highest anomaly correlation (0.86) for the interannual variability of TCs. Previous observational studies show a strong association between ENSO and Atlantic TC activity, as well as distinctions in the TC activities during eastern Pacific (EP) and central Pacific (CP) El Nino events. The analysis of track density and TC origin indicates that each model has different mean biases. Overall, the GCMs simulate the variability of Atlantic TCs well with weaker activity during EP El Nino and stronger activity during La Nina. For CP El Nino, there is a slight increase in the number of TCs as compared with EP El Nino. However, the spatial distribution of track density and TC origin is less consistent among the models. Particularly, there is no indication of increasing TC activity over the U.S. southeast coastal region as in observations. The difference between the models and observations is likely due to the bias of vertical wind shear in response to the shift of tropical heating associated with CP El Nino, as well as the model bias in the mean circulation