Air Flow Investigation for Location of Angle of Attack Head on a JN4h Airplane

The technical staff of the NACA at Langley Field, has made a series of free flight tests with a JN4h airplane in order to find the best place for an instrument for measuring the angle of attack. A "neutral zone" was found where the air remains either at rest relative to the undisturbed air beyond the influence of the airplane, or is set in motion parallel to the motion of the airplane. This zone is about midway between the two wings and slightly in front of, or at the vertical plane through the leading edges of the wings but the exact position as well as the outlines of the zone varies considerably as the conditions of flight change

Spontaneous ignition characteristics of gaseous hydrocarbon-air mixtures

Experiments are conducted to determine the spontaneous ignition delay times of gaseous propane, kerosine vapor, and n-heptane vapor in mixtures with air, and oxygen-enriched air, at atmospheric pressure. Over a range of equivalence ratios from 0.2 to 0.8 it is found that ignition delay times are sensibly independent of fuel concentration. However, the results indicate a strong dependence of delay times on oxygen concentration. The experimental data for kerosine and propane demonstrate very close agreement with the results obtained previously by Mullins and Lezberg respectively

Spontaneous Ignition Characteristics of Hydrocarbon Fuel-air Mixtures

Although the subject of spontaneous ignition of liquid fuels has received considerable attention in the past, the role of fuel evaporation in the overall spontaneous ignition process is still unclear. A main purpose of this research is to carry out measurements of ignition delay times, using fuels of current and anticipated future aeronautical interest, at test conditions that are representative of those encountered in modern gas turbine engines. Attention is focused on the fuel injection process, in particlar the measurement and control of man fuel drop size and fuel-air spatial distribution. The experiments are designed to provide accurate information on the role of fuel evaporation processes in determining the overall ignition delay time. The second objective is to examine in detail the theoretical aspects of spontaneous ignition in order to improve upon current knowledge and understanding of the basic processes involved, so that the results of the investigation can find general and widespead application

The Effect of Public Sector Labor laws on Collective Bargaining, Wages, and Employment

This paper examines the effect of the different legal environments for bargaining faced by public employees across the states on wage and employment outcomes for union and nonunion employees, and also on the extent of bargaining, using cross-section, within-city, and longitudinal analyses based on a newly-derived data set on public sector labor laws. We find that: (1) the legal environment is a significant determinant of the probability of collective bargaining coverage; (2) collective bargaining coverage raises wages and employment for covered employees; (3) a more favorable legal environment increases wages for all employees, but substantially reduces employment for employees not covered by a contract, while slightly reducing employment for employees who are covered by a contract. We also find evidence of significant spillovers of union wage effects to non-covered departments. We conclude by focusing on the effects of two specific legal provisions - arbitration and strike permitted clauses - on wages and employment.

The Legacy of Communist Labor Relations

This paper contrasts International Social Science Programme (ISSP) surveys for Hungary, supplemented with related survey data for East Germany, Poland, and Slovenia, with ISSP data for Western countries, to examine the extent to which workers in traditionally communist societies differ in their attitudes toward work conditions, wage inequality, the role of unions and the role of the state in determining labor market outcomes. We find sufficiently marked differences in responses between Hungary and the other previously communist countries and in Western countries to suggest that communism left an identifiable common legacy in the labor area. The citizens of former communist countries evince a greater desire for egalitarianism, are less satisfied with their jobs, and are more supportive of state interventions in the job market and economy than Westerners. These differences suggest that the move to a market economy will be marked by considerable 'social schizophrenia' due to an attitudinal legacy of their communist past.

Inequality and Economic Growth Over the Business Cycle: Evidence From U.S. State-Level Data

The purpose of this paper is to re-examine the empirical relationship between income inequality and economic growth using U.S. State-level data during the post-war period. The use of state-level data provides a sample that is relatively homogeneous in many non-economic characteristics, unlike the international data used in most previous work. Building upon prior research, this study addresses the issues of potential non-linearities in the relationship between inequality and growth, the influence of the cyclical condition during the year sampled, and possible bias in the measurement of economic growth. We find, using GMM estimators, that inequality is harmful to growth, and that the deleterious effects of inequality are greater for lower income states.

Poverty in Metropolitan Areas of the U.S.: Causes and Consequences

This paper re-examines the determinants of poverty using a pooled data set of 331 U.S. Metropolitan Statistical Areas (MSAs) measured over four decennial censuses from 1970 to 2000. Our principal conclusions are that the determinants of poverty that we have identified are relatively stable predictors of poverty levels, but that results for first differences are sensitive to the time period of estimation. We also examine whether poverty as an initial condition has an effect on future growth in incomes and/or employment, and our tentative conclusion is that a higher level of existing poverty is indeed a detriment to future growth.

Impacts of elevated atmospheric ozone on peatland below-ground DOC characteristics

Rising concentrations of tropospheric ozone are having detrimental impacts on the growth of crop and forest species and some studies have reported inhibition of the allocation of carbon below ground. The effects of ozone on peatland ecosystems have received relatively little attention, despite their importance within the global carbon cycle. During this study, cores from a Welsh minerotrophic fen and ombrotrophic bog were exposed to four ambient/ elevated ozone concentration regimes representing current and predicted 2050 profiles. A large and significant reduction in the concentration of porewater dissolved organic carbon (DOC) was recorded in the fen cores exposed to the elevated ozone concentrations (up to −55%), with a concurrent shift to a higher molecularweight of the remaining soil carbon. No effects of ozone on DOC concentrations or characteristics were recorded for the bog cores. The data suggest higher ozone sensitivity of plants growing in the fen-type peatland, that the impacts on the vegetation may affect soil carbon characteristics through a reduction in root exudates and that theremay have been a shift in the source of substrate DOC for microbial consumption from vegetation exudates to native soil carbon. Theremay also have been a direct effect of ozone molecules reacting with soil organic matter after being transported into the soil through the aerenchyma tissue of the overlying vegetation. These qualitative changes in the soil carbon in response to elevated ozone may have important implications for carbon cycling in peatland ecosystems, and therefore climate change