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.

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.

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.

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.

The burning of biomass - forests, grasslands, and agricultural fields after the harvest - is much more widespread and extensive than previously believed; most biomass burning is thought to be initiated by humans and is on the increase. This comprehensive volume is the first to consider biomass burning as a global phenomenon and to assess its impact on the atmosphere, on climate, and on the biosphere itself. The 63 chapters by 158 scientists - including leading biomass burn researchers from third-world countries, such as Brazil, Nigeria, Zaire, India, and China, where biomass burning is so prevalent - point to biomass burning as a significant driver of global change on our planet.Global Biomass Burning provides a convenient and current reference on such topics as the remote sensing of biomass burning from space, the geographical distribution of burning; the combustion products of burning in tropical, temperate, and boreal ecosystems; burning as a global source of atmospheric gases and particulates; the impact of biomass burning gases and particulates on global climate; and the role of biomass burning on biodiversity and past global extinctions.Also included are contributions on the importance of biomass burning from the International Geosphere-Biosphere Program: A Study of Global Change and from the International Global Atmospheric Chemistry Project, as well as policy options prepared by the U.S. Environmental Protection Agency for managing biomass burning to mitigate global climate change.Joel S. Levine is Senior Research Scientist in the Atmospheric Sciences Division, NASA Langley Research Center and is the Principal Investigator of NASA's research program on global biomass burning, Biospheric Research Program, Office of Space Sciences and Applications.

These proceedings describe the current state-of-the-art of ozone research. A wide range of topics is discussed including: emissions, transport and transformation of precursors of ozone and of ozone itself, the distribution of ozone, the deposition of ozone at the earth's surface, and its effects on man and the environment. Attention is also given to the role of stratospheric ozone and the role of the ultraviolet radiation which is transmitted through the ozone layer. Finally it describes in detail present and future policy measures to reduce the ozone in the lower atmosphere and to protect the ozone layer in the stratosphere. Many of the papers describe recent developments and new research results. Research carried out in both in Europe and in the United States is described, as are the policy measures which are being taken by both European and U.S. governments.

These proceedings describe the current state-of-the-art of ozone research. A wide range of topics is discussed including: emissions, transport and transformation of precursors of ozone and of ozone itself, the distribution of ozone, the deposition of ozone at the earth's surface, and its effects on man and the environment. Attention is also given to the role of stratospheric ozone and the role of the ultraviolet radiation which is transmitted through the ozone layer. Finally it describes in detail present and future policy measures to reduce the ozone in the lower atmosphere and to protect the ozone layer in the stratosphere. Many of the papers describe recent developments and new research results. Research carried out in both in Europe and in the United States is described, as are the policy measures which are being taken by both European and U.S. governments

Procedural and legal issues in the EC's decision-making process on the internal and international level.