The purpose of Federal Aviation Regulations Part 77, entitled ＂Objects Affecting Navigable Airspace＂, is to identify potential hazards and prevent adverse impacts to the safe and efficient use of navigable airspace....The purpose of Federal Aviation Regulations Part 77, entitled ＂Objects Affecting Navigable Airspace＂, is to identify potential hazards and prevent adverse impacts to the safe and efficient use of navigable airspace. The OIS （obstruction identification surfaces） represent these regulations, identify objects that penetrate these imaginary surfaces, evaluate hazardous effects, and ensure safe separations of aircraft from obstructions. The OIS evaluation is often used for selecting airfield locations and runway orientations. More importantly, the OIS evaluation is an airport＇s safeguard against flawed urban development, especially for airports near rapidly expanding cities. Without accurate analysis tools, hand-calculation errors on the OIS can occur and cause adverse impacts to airport safety. Applying the GIS （geographic information system） features of geospatial data and 3D formats, this paper proposes a model named GIS Obstruction Model which is capable of precisely calculating maximum allowable heights and creating visual imagery of penetrating obstructions. The special features of the model include web-based design, adaptability to any airport, user-friendly multiple inquiry methods, quick response to online inquiries, and response with 3D visual reality. The proposed G1S Obstruction Model is useful for airport planning, architecture design, safety management or civil engineering permit review.展开更多
Many coal enterprises have built the videoconference systems on their LAN （Local Area Network）. As the development of these enterprises, their organizations are distributed over our country and even over the world. ...Many coal enterprises have built the videoconference systems on their LAN （Local Area Network）. As the development of these enterprises, their organizations are distributed over our country and even over the world. Therefore, the videoconference systems have to run over WAN （Wide Area Network）. Normally, the structure of a videoconference system is center_division including MCU （multi control unit）and participants. No QoS and security assurance are available now because all videoconference system is based on TCP/IP. Therefore, the system stability is absolutely depended on the Network. This paper discussed how to anti ARP attacking. The method discussed in this paper is based on TCP/IP.展开更多
文摘The purpose of Federal Aviation Regulations Part 77, entitled ＂Objects Affecting Navigable Airspace＂, is to identify potential hazards and prevent adverse impacts to the safe and efficient use of navigable airspace. The OIS （obstruction identification surfaces） represent these regulations, identify objects that penetrate these imaginary surfaces, evaluate hazardous effects, and ensure safe separations of aircraft from obstructions. The OIS evaluation is often used for selecting airfield locations and runway orientations. More importantly, the OIS evaluation is an airport＇s safeguard against flawed urban development, especially for airports near rapidly expanding cities. Without accurate analysis tools, hand-calculation errors on the OIS can occur and cause adverse impacts to airport safety. Applying the GIS （geographic information system） features of geospatial data and 3D formats, this paper proposes a model named GIS Obstruction Model which is capable of precisely calculating maximum allowable heights and creating visual imagery of penetrating obstructions. The special features of the model include web-based design, adaptability to any airport, user-friendly multiple inquiry methods, quick response to online inquiries, and response with 3D visual reality. The proposed G1S Obstruction Model is useful for airport planning, architecture design, safety management or civil engineering permit review.
文摘Many coal enterprises have built the videoconference systems on their LAN （Local Area Network）. As the development of these enterprises, their organizations are distributed over our country and even over the world. Therefore, the videoconference systems have to run over WAN （Wide Area Network）. Normally, the structure of a videoconference system is center_division including MCU （multi control unit）and participants. No QoS and security assurance are available now because all videoconference system is based on TCP/IP. Therefore, the system stability is absolutely depended on the Network. This paper discussed how to anti ARP attacking. The method discussed in this paper is based on TCP/IP.
