Self-stabilizing interval routing algorithm with low stretch factor

A compact routing scheme is a routing strategy which suggests routing tables that are space efficient compared to traditional all-pairs shortest path routing algorithms. An Interval Routing algorithm is a compact routing algorithm which uses a routing table at every node in which a set of destination addresses that use the same output port are grouped into intervals of consecutive addresses. Self-stabilization is a property by which a system is guaranteed to reach a legitimate state in a finite number of steps starting from any arbitrary state. A self-stabilizing Pivot Interval Routing (PIR) algorithm is proposed in this work. The PIR strategy allows routing along paths whose stretch factor is at most five, and whose average stretch factor is at most three with routing tables of size O(n3/2log 23/2n) bits in total, where n is the number of nodes in the network. Stretch factor is the maximum ratio taken over all source-destination pairs between the length of the paths computed by the routing algorithm and the distance between the source and the destination. PIR is also an Interval Routing Scheme (IRS) using at most 2n( 1+lnn)1/2 intervals per link for the weighted graphs and 3n(1+ lnn)1/2 intervals per link for the unweighted graphs. The preprocessing stage of the PIR algorithm consists of nodelabeling and arc-labeling functions. The nodelabeling function re-labels the nodes with unique integers so as to facilitate fewer number of intervals per arc. The arc-labeling is done in such a fashion that the message delivery protocol takes an optimal path if both the source and the destination are located within a particular range from each other and takes a near-optimal path if they are farther from each other

Delineation of Landslide, Flash Flood, and Debris Flow Hazards in Utah

During 1982, 1983, and 1984, abnormally wet conditions in Utah triggered flash floods, landslides, and debris flows. Pore pressures built in hillside soils below melting snows and during prolonged periods of rainfall until the mass suddenly gave way, sometimes as a landslide and other times as a non-Newtonian debris flow that moved rapidly long distances down mountain slopes until finally stiffened by moisture loss or velocity loss because of flatter gradients. Also, runoff from heavy rainfall bursts picked up weathered and other loose material that accumulated on land surfaces over long dry periods . The sediment laden waters flowed out of mountain canyons onto lowlands where they deposited their loads, filled channels and c logged culverts, and then spread over the land surface to infiltrate, except as intercepted and diverted by streets, storm sewers, and irrigation canals. These were in turn often over topped to cause flooding in areas with no natural hazard. Snow melt runoff continued over extended periods, keeping stream flows too high to be contained within the clogged streams, and causing water to flow down streets for weeks disrupting traffic and inundating low-lying property. In closed basins, the waters eventually drain into a terminal lake where rising waters gradually inundated large areas. This complex of interrelated phenomena created a hazard situation that is greatest at the toe of the mountain slopes and concentrates where mountain canyons drain onto alluvial fans and the water spreads in a pattern that varies substantially from storm to storm. These hillside areas are prime res identical site s and command a high pr ice in the market. Development that should not be located in high hazard areas is reasonable a little further down slope where the risk is less. Quantitative methods are needed for mapping flood, debris, and landslide risks in these basin margin areas so that objective decisions can be made on where to locate and how to landscape and design buildings. Monitoring programs and warning systems are needed to track emerging hazards, emergency plans, and get people to respond. During two spring months of 1983, Utah sustained direct damages from landslides and debris floods in excess of 250 million dollars. Public official.s and residents were prepared for water flooding. However, neither the scientific community nor the agencies responsible for dealing with emergency situations were prepared for the widespread 1andslides and devastating debris flows. At least 92 significant landslides along a 30-mile length of the Wasatch Front Mountains sent torrents of water and debris down on the residential areas below. Along the Wasatch Plateau, more than 1000 landslides occurred. Additional massive landslides in Spanish Fork Canyon, Utah County, created Thistle Lake, and in 12-Hile Canyon, Sanpete County, dammed a river and sent a 30-foot high flash flood surge down the canyon. These devastating floods, landslides and debris flows were so extensive that 22 of Utah\u27s 28 counties were declared national disaster areas

Voyager spacecraft system. Prelimiary design, volume A /book 3 of 4/ - Flight spacecraft preferred design - G and C, Pwr, Eng'g mech, prop

Voyager spacecraft subsystem level requirements in guidance and control, power, propulsion, and engineering mechanics including structures and packagin