2,445 research outputs found

    All That Sprawl, Y’all: An Analysis of Development on Steinwehr Avenue and York Street in Gettysburg, Pennsylvania, from 1971 to 2014

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    The advent of the automobile transformed the American landscape in the 20th century. In conjunction with the increasing importance of the automobile, numerous post-WW II government programs such as the Interstate Highway System encouraged suburban sprawl. Towns and cities adjacent to tourist attractions, known as gateway communities, face unique problems caused by sprawl. Gettysburg, Pennsylvania, is an example of a gateway community as it includes the Gettysburg National Military Park. Two study sites, portions of Steinwehr Avenue and York Street, were studied to analyze the effects of sprawl in Gettysburg. The sites were analyzed using ArcGIS, data compiled from historic phonebooks, and discussions with local business owners. Development along York Street exemplifies an auto-centric culture with many regional and national chain establishments set back from the road. Steinwehr Avenue represents a walkable community comprising on-street parking, sidewalks, and local “mom-and-pop” establishments. Trends associated with categories of businesses varied between the two sites and revealed different development patterns. We predict that that York Street will continue to sprawl while Steinwehr Avenue development will be limited due to its close proximity to the battlefield

    The impact of alternative bank monitoring policies on corporate investment and financing decisions

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    Much of the benefit from bank loans is generated by the specialized monitoring and information gathering role provided by financial institutions, including their role in facilitating the reorganization of firms experiencing financial distress. Despite these numerous benefits, it is somewhat surprising that aggregate trends suggest that the corporate sector has decreased its reliance on bank loans. We model the relationship between alternative bank monitoring policies and corporate investment and financing decisions. Rather than taking the monitoring characteristics of the bank as fixed, we examine the effects of changes in bank monitoring policies. We provide insights into how the banking sector evolves through time.Banks and banking ; Corporations - Finance

    Effective Testing Procedures For Partial Vision Students Utilizing The Microcomputer

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    A testing program utilizing a voice synthesizer and double-sized graphics was developed for high school partial vision students in a Business Education Microcomputer Applications class. Prior to the program, partial vision students had failing test grades. In order to take a test, the partial vision student had to go to a resource lab to use a reader. This took a great amount of time and the partial vision student missed regular classroom activities. The program was implemented for 10 weeks. After the partial vision students were trained to use the speech synthesizer for one week, tests were administered on the computer through a program designed to facilitate the text. Students were timed and the number of times a student asked for assistance was recorded. At the conclusion of the program, the majority of the test scores were passing. The amount of time needed to take a test was cut in half and the students had a better attitude about their own classroom performance. Recommendations include a lab equipped with speech synthesizers and enlarged print. Suggestions are also given for the teacher who receives a partial vision student in the classroom. (Appendices Include a checklist of speech synthesizer commands, a sample weekly log, an attitudinal survey form, a software evaluation form, a program listing for the testing program, and graphs of the results of the study.

    What are the odds? option-based forecasts of FOMC target changes

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    This article uses probability forecasts derived from options to assess evolving market uncertainty about Federal Reserve monetary policy actions in a variety of recent events and episodes. Options on federal funds futures contracts reveal a complete probability density function over possible Federal Reserve target rates, thus augmenting the expectations provided by federal funds futures contracts. Option-based forecasts are most useful when more than two federal funds target outcomes are plausible at an upcoming policy meeting.Federal Open Market Committee ; Forecasting ; Monetary policy

    Independent Orbiter Assessment (IOA): Analysis of the orbiter main propulsion system

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    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Main Propulsion System (MPS) hardware are documented. The Orbiter MPS consists of two subsystems: the Propellant Management Subsystem (PMS) and the Helium Subsystem. The PMS is a system of manifolds, distribution lines and valves by which the liquid propellants pass from the External Tank (ET) to the Space Shuttle Main Engines (SSMEs) and gaseous propellants pass from the SSMEs to the ET. The Helium Subsystem consists of a series of helium supply tanks and their associated regulators, check valves, distribution lines, and control valves. The Helium Subsystem supplies helium that is used within the SSMEs for inflight purges and provides pressure for actuation of SSME valves during emergency pneumatic shutdowns. The balance of the helium is used to provide pressure to operate the pneumatically actuated valves within the PMS. Each component was evaluated and analyzed for possible failure modes and effects. Criticalities were assigned based on the worst possible effect of each failure mode. Of the 690 failure modes analyzed, 349 were determined to be PCIs

    Thin-film sulfuric acid anodizing as a replacement for chromic acid anodizing

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    Chromic acid has long been used to produce a thin, corrosion resistant (Type I) coating on aluminum. Following anodizing, the hardware was sealed using a sodium dichromate solution. Sealing closes up pores inherent in the anodized coating, thus improving corrosion resistance. The thinness of the brittle coating is desirable from a fatigue standpoint, and chromium was absorbed by the coating during the sealing process, further improving corrosion resistance. Unfortunately, both chromic acid and sodium dichromate contain carcinogenic hexavalent chromium. Sulfuric acid is being considered as a replacement for chromic acid. Sulfuric acid of 10-20 percent concentration has traditionally been used to produce relatively thick (Types II and III) or abrasion resistant (Type III) coatings. A more dilute, that is five weight percent, sulfuric acid anodizing process, which produces a thinner coating than Type II or III, with nickel acetate as the sealant has been developed. The process was evaluated in regard to corrosion resistance, throwing power, fatigue life, and processing variable sensitivity, and shows promise as a replacement for the chromic acid process

    Metamaterial Coatings for Broadband Asymmetric Mirrors

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    We report on design and fabrication of nano-composite metal-dielectric thin film coatings with high reflectance asymmetries. Applying basic dispersion engineering principles to model a broadband and large reflectance asymmetry, we obtain a model dielectric function for the metamaterial film, closely resembling the effective permittivity of disordered metal-dielectric nano-composites. Coatings realized using disordered nanocrystalline silver films deposited on glass substrates confirm the theoretical predictions, exhibiting symmetric transmittance, large reflectance asymmetries and a unique flat reflectance asymmetry.Comment: 4 pages, 4 figures, submitted to Optics Letter

    Effect of sulfate aerosol on tropospheric NOx and ozone budgets: Model simulations and TOPSE evidence

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    The distributions of NOx and O3 are analyzed during TOPSE (Tropospheric Ozone Production about the Spring Equinox). In this study these data are compared with the calculations of a global chemical/transport model (Model for OZone And Related chemical Tracers (MOZART)). Specifically, the effect that hydrolysis of N2O5 on sulfate aerosols has on tropospheric NOx and O3 budgets is studied. The results show that without this heterogeneous reaction, the model significantly overestimates NOx concentrations at high latitudes of the Northern Hemisphere (NH) in winter and spring in comparison to the observations during TOPSE; with this reaction, modeled NOx concentrations are close to the measured values. This comparison provides evidence that the hydrolysis of N2O5 on sulfate aerosol plays an important role in controlling the tropospheric NOx and O3 budgets. The calculated reduction of NOx attributed to this reaction is 80 to 90% in winter at high latitudes over North America. Because of the reduction of NOx, O3 concentrations are also decreased. The maximum O3reduction occurs in spring although the maximum NOx reduction occurs in winter when photochemical O3 production is relatively low. The uncertainties related to uptake coefficient and aerosol loading in the model is analyzed. The analysis indicates that the changes in NOxdue to these uncertainties are much smaller than the impact of hydrolysis of N2O5 on sulfate aerosol. The effect that hydrolysis of N2O5 on global NOx and O3 budgets are also assessed by the model. The results suggest that in the Northern Hemisphere, the average NOx budget decreases 50% due to this reaction in winter and 5% in summer. The average O3 budget is reduced by 8% in winter and 6% in summer. In the Southern Hemisphere (SH), the sulfate aerosol loading is significantly smaller than in the Northern Hemisphere. As a result, sulfate aerosol has little impact on NOx and O3 budgets of the Southern Hemisphere

    TERRA/MOPITT Measurements of Tropospheric Carbon Monoxide Distributions in Support of INTEX

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    Interaction with the ongoing satellite measurements programs was an important goal of INTEX- A. The Terra/MOPITT instrument had been making global measurements of the tropospheric carbon monoxide (CO) distribution for 4 years, and was in a unique position to provide valuable support during the field campaign. Remote sensing of CO directly addressed the scientific questions motivating the IXTEX-A strategy and deployment, and measurement of this gas was rated as being mission critical. CO is an important trace gas in tropospheric chemistry due to its role in determining the atmospheric oxidizing capacity, as an ozone precursor, and as an indicator and tracer of both natural and anthropogenic pollution arising from incomplete combustion. The satellite perspective provided the more general temporal and spatial context to the aircraft and ground-based measurements during the subsequent scientific analysis. We proposed to build on the experience of supplying MOPITT data to previous field campaigns, such as TRACE-P. We provided expedited MOPITT data processing in near real-time, along with basic analysis of the measurements to indicate, where possible, the origin of the CO plumes that impacted the regions of flight operations and other in situ measurement activities. To ensure maximum exploitation of the satellite information, we will also had a scientist in the field to present and interpret the MOPITT data for the INTEX team, and to help ensure its utility in flight planning

    Quantifying black carbon deposition over the Greenland ice sheet from forest fires in Canada

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    Black carbon (BC) concentrations observed in 22 snowpits sampled in the northwest sector of the Greenland ice sheet in April 2014 have allowed us to identify a strong and widespread BC aerosol deposition event, which was dated to have accumulated in the pits from two snow storms between 27 July and 2 August 2013. This event comprises a significant portion (57% on average across all pits) of total BC deposition over 10 months (July 2013 to April 2014). Here we link this deposition event to forest fires burning in Canada during summer 2013 using modeling and remote sensing tools. Aerosols were detected by both the Cloud‐Aerosol Lidar with Orthogonal Polarization (on board CALIPSO) and Moderate Resolution Imaging Spectroradiometer (Aqua) instruments during transport between Canada and Greenland. We use high‐resolution regional chemical transport modeling (WRF‐Chem) combined with high‐resolution fire emissions (FINNv1.5) to study aerosol emissions, transport, and deposition during this event. The model captures the timing of the BC deposition event and shows that fires in Canada were the main source of deposited BC. However, the model underpredicts BC deposition compared to measurements at all sites by a factor of 2–100. Underprediction of modeled BC deposition originates from uncertainties in fire emissions and model treatment of wet removal of aerosols. Improvements in model descriptions of precipitation scavenging and emissions from wildfires are needed to correctly predict deposition, which is critical for determining the climate impacts of aerosols that originate from fires
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