2,188 research outputs found

    Assessment of the Effects of Entrainment and Wind Shear on Nuclear Cloud Rise Modeling

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    The Missile Defense Agency (MDA) plans to construct, during a two-week period, an X-Band Radar (XBR) on Shemya, AK. Wind speeds must not, at any time during the construction, exceed a 25 knot limit set by the MDA for lifting the massive dome panels into place. The goal of this research was to explore the possibilities of long-range forecasts to determine the feasibility of predicting any upcoming two-week windows of opportunity, well in advance, that will ensure the successful completion of constructing the XBR on Shemya. In order to reach this goal, the following objectives were achieved; (1) a climatological wind study for Shemya to assess the optimal climatological window to build the XBR, (2) a detailed synoptic study over the North Pacific, to gain an understanding of how synoptic weather systems develop, move, and vary on an annual basis, (3) a traditional statistical analysis of the data followed by a Classification and Regression Tree (CART) analysis for pattern recognition of global teleconnection indices, and (4) develop forecasting decision trees to assist the 11th Operational Weather Squadron (OWS) Alaskan forecast hub in this daunting task. The Aleutian Island chain is plagued by persistent strong winds, since the Aleutian Low and expanding polar vortex affect the region in the winter, as do tropical storms and frontal passages in the summer. This, combined with Shemya being located near the exit region of the climatological storm track off the East Asian continent, makes the island one of the most challenging forecast locations in the Northern Hemisphere. This study compares surface winds and teleconnection indices, as computed by the Climate Prediction Center (CPC), to statistically analyze the data. The data were analyzed using standard statistical regression techniques, including linear and multiple linear regression methods, and then CART analysis was used for large-scale pattern recognition

    Methods for Monitoring Process Control and Capability in the Presence of Autocorrelation

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    When standard control charts are applied to a process whose measurements of quality exhibit autocorrelation, the performance of those charts can be considerably different than that expected when no autocorrelation is present. To model this performance, the existing definitions of assignable and chance causes of variation are extended to account for the variation induced by the autocorrelation structure. The application of statistical thinking toward continuous process improvement using the proposed taxonomy is discussed. A method to select control limits which yield a specified average run length in the absence of assignable causes of variation and which is suitable for use on processes whose behavior can be modelled as an ARMA(1,1) process is developed. The current paradigm for process improvement is centered around monitoring the state of statistical control. A new paradigm, based upon monitoring process capability, is proposed. The time varying aspects of capability are highlighted. A capability monitoring system for stationary ARMA(1,1) processes is developed and compared to other standard methods. The benefits of additional knowledge are demonstrated by simulating the response of capability monitoring systerns tailored to independent normal and mixed ARMA(1,1) models to shifts in the mean and variance

    Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel Part 1: 8-Ply In-Autoclave Facesheets

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    Four honeycomb sandwich panels, representing 1/16th arc segments of a 10-m diameter barrel section of the heavy lift launch vehicle, were manufactured under the NASA Composites for Exploration program and the NASA Space Launch Systems program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: inautoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3.00- by 5.00-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center. Furthermore, linear eigenvalue and geometrically nonlinear finite element analysis was performed to predict the compressive response of the 3.00- by 5.00-ft panels. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panel composed of 8-ply, IM7/977-3 facesheets (referred to Panel A). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yield good qualitative and quantitative predictions. Additionally, it was predicted correctly that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber misalignments, and three-dimensional (3 D) effects on the compressive response of the panel

    Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel

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    Four honeycomb sandwich panel types, representing 1/16th arc segments of a 10-m diameter barrel section of the Heavy Lift Launch Vehicle (HLLV), were manufactured and tested under the NASA Composites for Exploration program and the NASA Constellation Ares V program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: in-autoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3- by 5-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center (LaRC). Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of each 3- by 5-ft panel. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panels composed of 6-ply, IM7/977-3 facesheets (referred to as Panels B-1 and B-2). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yield good qualitative and quantitative predictions. Additionally, it was correctly predicted that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber angle misalignments, and three-dimensional (3-D) effects on the compressive response of the panel

    Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel: Comparison of In- and Out-of-Autoclave Facesheet Configurations

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    Four honeycomb sandwich panels, representing 1/16th arc segments of a 10-m diameter barrel section of the Heavy Lift Launch Vehicle, were manufactured and tested under the NASA Composites for Exploration and the NASA Constellation Ares V programs. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.0 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: in-autoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3 ft. by 5 ft. panels were cut from the 1/16th barrel sections and tested under compressive loading. Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of each 3 ft. by 5 ft. panel. To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yielded good qualitative and quantitative predictions. Additionally, it was correctly predicted that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber angle misalignments, and three-dimensional effects on the compressive response of the panel

    The correlation of mutations and expressions of genes within the PI3K/Akt/mTOR pathway in breast cancer : a preliminary study

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    There is an urgent need to seek new molecular biomarkers helpful in diagnosing and treating breast cancer. In this elaboration, we performed a molecular analysis of mutations and expression of genes within the PI3K/Akt/mTOR pathway in patients with ductal breast cancer of various malignancy levels. We recognized significant correlations between the expression levels of the studied genes. We also performed a bioinformatics analysis of the data available on the international database TCGA and compared them with our own research. Studies on mutations and expression of genes were conducted using High-Resolution Melt PCR (HRM-PCR), Allele-Specific-quantitative PCR (ASP-qPCR), Real-Time PCR molecular methods in a group of women with ductal breast cancer. Bioinformatics analysis was carried out using web source Ualcan and bc-GenExMiner. In the studied group of women, it was observed that the prevalence of mutations in the studied PIK3CA and AKT1 genes was 29.63%. It was stated that the average expression level of the PIK3CA, PIK3R1, PTEN genes in the group of breast cancer patients is lower in comparison to the control group, while the average expression level of the AKT1 and mTOR genes in the studied group was higher in comparison to the control group. It was also indicated that in the group of patients with mutations in the area of the PIK3CA and AKT1 genes, the PIK3CA gene expression level is statistically significantly lower than in the group without mutations. According to our knowledge, we demonstrate, for the first time, that there is a very strong positive correlation between the levels of AKT1 and mTOR gene expression in the case of patients with mutations and without mutations

    2021 State of the Commonwealth Report

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    This is Old Dominion University’s seventh annual State of the Commonwealth Report. While it represents the work of many people connected in various ways to the university, the report does not constitute an official viewpoint of Old Dominion, its president, Brian O. Hemphill, Ph.D., the Board of Visitors, the Strome College of Business or the generous donors who support the activities of the Dragas Center for Economic Analysis and Policy. With the 2021 election in the rearview mirror, the question now becomes: Where does Virginia go from here? Our work seeks to contribute to this conversation without glossing over the challenges we face. We want to encourage the difficult conversations to help Virginia improve the outcomes for all its residents in the coming years

    Biomarkers of brain ischemia-reperfusion injury after carotid endarterectomy

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    Abstract Background: Endarterectomy of the internal carotid artery (CEA) is a surgical procedure used to prevent cerebral ischemic stroke. Available data from previous literature indicates that CEA may lead to complications in the form of cerebral ischemia-reperfusion syndrome and oxidative stress. The aim of this study was to evaluate the serum levels of oxidative stress-related biomarkers such as 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA) in patients who underwent CEA. Material and methods. Twenty-four patients with severe internal carotid artery stenosis participated in the study. Serum samples were taken from patients at three different times: within 24 hours preoperatively to CEA, 12 hours postoperatively, and 48 hours postoperatively. Serum 8-OHdG and MDA levels were measured using a commercially available enzyme-linked immunosorbent assay. Results: Serum 8-OHdG levels indicated statistically significant elevation 12 hours after surgery when compared to preoperative levels (p<0.05). A further increase in the concentration of this parameter was observed 48 hours after surgery when compared to the previous measurement, however, this increase was no longer statistically significant (p=0.05). Furthermore, serum MDA levels also indicated a statistically significantly elevation 48 hours after surgery when compared to preoperative levels (p<0.05). Conclusion: Our study showed that CEA causes an increase in blood levels of 8-OHdG and MDA, which may be related to the occurrence of oxidative stress during cerebral ischemia-reperfusion injury. Therefore, 8-OHdG and MDA may represent corresponding markers of cerebral ischemia-reperfusion complications in patients undergoing CEA

    The State of the Region: Hampton Roads 2021

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    [From the introductory material] This is Old Dominion University’s 22nd annual State of the Region Report. While it represents the work of many people connected in various ways to the university, the report does not constitute an official viewpoint of Old Dominion, its president, Brian O. Hemphill, Ph.D., the Board of Visitors, the Strome College of Business or the generous donors who support the activities of the Dragas Center for Economic Analysis and Policy. Over the past year, we have endured the depths of the COVID-19 pandemic, the introduction of vaccines and a return to a semblance of normality in Hampton Roads. Even as the economy recovers in the region, Virginia and the nation, we cannot forget that some have been left behind. Invigorating growth that raises the fortunes of all is the challenge that lies before us. This task will involve difficult discussions about how to diversify our economy in the coming years. Hampton Roads plays a significant role in national security, provides college education to thousands of Virginians and is culturally diverse. Given these realities and the fact that many residents live in one community and work in another, solutions to our regional challenges will require conversations and policies that span jurisdictional boundaries. If there is an overarching lesson to be learned from the pandemic, it is simply that we are all in this together
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