50 resultados para Landscape protection
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
In view of the growing social demand, the Council of Europe's Congress of Local and Regional Authorities (CLRAE) drew up the European Landscape Convention to promote landscape protection, management and planning, and to organize European co-operation on landscape issues in Europe. This paper summarizes the properties, origins, structure and content of the convention, and discusses the definitions on landscape and landscape policy to which the convention refers. Moreover, this paper sums up and concludes the perspective of landscape ecology in Europe.
Resumo:
Hypersonic vehicles represent future trends of military equipments and play an important role in future war. Thermal protection materials and structures, which relate to the safety of hypersonic vehicles, are one of the most key techniques in design and manufacture of hypersonic vehicles. Among these materials and structures, such as metallic temperature protection structure, the temperature ceramics and carbon/carbon composites are usually adopted in design. The recent progresses of research and application of ultra-high temperature materials in preparation, oxidation resistance, mechanical and physical characterization are summarized.
Resumo:
A new idea of drag reduction and thermal protection for hypersonic vehicles is proposed based on the combination of a physical spike and lateral jets for shock-reconstruction. The spike recasts the bow shock in front of a blunt body into a conical shock, and the lateral jets work to protect the spike tip from overheating and to push the conical shock away from the blunt body when a pitching angle exists during flight. Experiments are conducted in a hypersonic wind tunnel at a nominal Mach number of 6. It is demonstrated that the shock/shock interaction on the blunt body is avoided due to injection and the peak pressure at the reattachment point is reduced by 70% under a 4A degrees attack angle.
Resumo:
Experimental research on a 150 kW arc-heated plasma testing facility was conducted. Stable plasma jets with different gas compositions, temperatures and velocities were obtained at chamber pressure between 400 Pa – 100 kPa. Stagnation ablation experiments were conducted on samples of typical super alloys used for thermal protection systems. The microstructure and hardness of alloys before and after ablation were compared.
Resumo:
P> Widespread hunting throughout Amazonia threatens the persistence of large primates and other vertebrates. Most studies have used models of limited validity and restricted spatial and temporal scales to assess the sustainability. We use human-demographi