Suchergebnisse

An Advanced Development Program (ADP) to develop and demonstrate effective Atmospheric Electricity Hazards Protection (AEHP) for the fighter, transport/bomber, helicopter and cruise missile classes of air vehicles is being conducted under an Air Force Wright Aeronautical Laboratories (AFWAL) contract with Boeing Military Airplane Company (BMAC). Other Government agencies are also supporting the ADP. The parameters characterizing the lightning threat have been defined for moderate and severe flashes ; e.g., 200 kA peak and 200 kA/microsecond rise rate for the severe threat lightning current. The attachment of lightning flashes to aircraft has resulted in many losses of aircraft in the past. The losses have been caused by both physical damage to the aircraft frame or structure, and electrical effects to aircraft flight critical elements and systems. The losses associated with upset and/or damage may increase with the advent of sensitive integrated circuitry being used in flight critical applications, and the use of composite material in these airframes and structures thereby reducing its electromagnetic shielding effectiveness. Protection concepts ; e.g., circuit and system shielding, terminal protection, conducting floors and cable protection ; may be used to prevent damage. A design methodology considering airframe characteristics, and circuit and system characteristics and criticality, which will lead to identification of balanced protection schemes is presented. Incorporation of AEHP is expected to enhance the operational flexibility of air vehicles through increased confidence of all-weather operational integrity. The effectiveness demonstration phase of the AEHP ADP using a modified F-14 airframe with advanced avionic and power systems is described. An ACAP helicopter is also to be used as a testbed. The testbeds will be subjected to low-level continuous wave (CW), moderate-level pulse, and severe-level pulse current injection. This method evaluates the safety margin of the generic protection design.

Due to the threat of a possible global climate change and the greenhouse effect caused by constituents of anthropogenic origin in the atmosphere, air quality has become a major environmental issue. As a consequence, emissions into the atmosphere need to be monitored and controlled. Measurement of Atmospheric Emissions presents technologies for emission control and analysis from industrial and energy plants. The author explains the physical and chemical basis before proceeding to the practical performance. This publication provides the reader with the knowledge necessary to critically analyze and investigate emission measurement techniques. It will be of great interest to researchers and engineers in the fields of environmental technology and air pollution control. It will assist in the choice of the most appropriate instruments for various purposes and circumstances

Arguing that atmospheric pollution is a worldwide problem & that its solution requires global policy decisions, areas of potential international collaboration on this issue are explored. Barriers to cooperation are identified, most predominantly the anarchic state system. Different countries have dissimilar problems with & solutions to environmental issues. The environmental revolutionism of the 1970s is assessed, along with the effect of five multilateral emission reduction agreements signed during the era. It is concluded that there were three major developments that contributed toward the birth of atmospheric pollution controls: ecological interdependence, technological developments, & increased public influence on governmental policymakers. 30 References. Adapted from the source document.

There is ever increasing concern about both the ozone depletion in the stratosphere and the increase in the ozone concentration in the troposphere. As a consequence, there is growing interest in total ozone surface and satellite observations, surface UV measurements and the interpretation of results to assess potential impacts of UV radiation enhancement on man and the biosphere. The volume analyses problems of total ozone and UV-B variability. Further, it treats tropospheric ozone changes as well as the responsible factors, such as air pollution, chemical and photochemical reactions coupled with air transport. Some key problems of numerical modelling are also discussed. Another subject is the development of remote sensing techniques to retrieve minor optically active components of the atmosphere

This article examines the prospects for further international control of atmospheric pollution. Air pollution has become a global policy problem, control of which requires the collaboration of many states. Despite the need for co-operation, however, the protection of the global environment is problematical in the anarchic state system. Co-operation is constrained by the fact that states are not equally affected by pollution and have dissimilar interests in environmental protection. Nevertheless, even though the prospects for environmental co-operation did not seem promising in the 1970s, five multilateral agreements were signed to reduce emissions of air pollutants. Three changes in particular contributed to the emergence of atmospheric pollution controls: the imperatives of ecological interdependence, technological developments, and growing public pressure on policy-makers.

Radionuclides produced by past nuclear weapon test explosions comprise the largest source of anthropogenic radioactivity released into the earth's atmosphere to date. This volume presents data and models about the fate of the released radionuclides and their possible effects on human health. It is divided into the following three parts: - Source Term Studies; - Dose Reconstruction; - Ecological and Health Effects, and comprises both Western and formerly secret Soviet research studies, illuminates past and current research

Methane plays many important roles in the earth's environment. It is a potent "greenhouse gas" that warms the earth; controls the oxidizing capacity of the atmosphere (OH) indirectly affecting the cycles and abundances of many atmospheric trace gases; provides water vapor to the stratosphere; scavenges chlorine atoms from the stratosphere, terminating the catalytic ozone destruction by chlorine atoms, including the chlorine released from the man-made chlorofluorocarbons; produces ozone, CO, and CO2 in the troposphere; and it is an index of life on earth and so is present in greater quantities during warm interglacial epochs and dwindles to low levels during the cold of ice ages. By all measures, methane is the second only to CO2 in causing future global warming. The book presents a comprehensive account of the current understanding of atmospheric methane, and it is an end point for summarizing more than a decade of intensive research on the global sources, sinks, concentrations, and environmental role of methane

Airborne pollution of the marine environment has not received great attention in the literature. This is certainly a reflection of the fact that, for the longest time, this type of pollution was neglected in international efforts to cooperate for the protection of the marine environment. However, the last few years have witnessed considerable activity in this area and some stock-taking is in order.