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Restoration Scheme (restoration + scheme)

Distribution by Scientific Domains

Engineering	50%
Earth and Environmental Science	50%

Selected Abstracts

Capacity provisioning and failure recovery for Low Earth Orbit satellite constellation

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2003
Jun Sun
This paper considers the link capacity requirement for an LEO satellite constellation. We model the constellation as an N×N mesh-torus topology under a uniform all-to-all traffic model. Both primary capacity and spare capacity for recovering from a link or node failure are examined. In both cases, we use a method of ,cuts on a graph' to obtain lower bounds on capacity requirements and subsequently find algorithms for routing and failure recovery that meet these bounds. Finally, we quantify the benefits of path-based restoration over that of link-based restoration; specifically, we find that the spare capacity requirement for a link-based restoration scheme is nearly N times that for a path-based scheme. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Contribution of geophysics to outlining the foundation structure of the Islamic Museum, Cairo, Egypt

ARCHAEOLOGICAL PROSPECTION, Issue 3 2005
A. M. Abbas
Abstract The Islamic museum was erected in 1896. The building is situated in the heart of Cairo (capital of Egypt) and holds marvellous Islamic antiquities and priceless ancient hand-writing and rare books. Recently, a restoration scheme has been planned to secure the old building which suffers from weakened foundations. In addition, the wooden roofs will be replaced by concrete ones and an extra floor will be integrated into the building. Unfortunately, the architecture construction charts were neither available nor obtainable. Therefore, the structure of the foundations and the base walls of the building had to be outlined. At the time of construction, three major fundamental wall designs were dominant and were to be considered during the work approach. Ground-penetrating radar (GPR) and dipole,dipole resistivity imaging have been integrated to (define the structure of the foundation walls of the building. A Ramac2 system connected to a 500,MHz antenna has been utilized for conducting the GPR survey. In addition, a Terrameter SAS 1000 single channel device has been used for performing the resistivity profiles. At accessible spaces around the building GPR and resistivity profiles were obtained. The GPR analysis has revealed the depth of the foundation walls to be about 0.9,m from the ground surface with a width close to 0.6,m. The wall design is close to a straight wall style. Furthermore, the analysis of the dipole,dipole resistivity measurements has matched the geology of the area, where subsoil anomalies may be due to the scattered limestone blocks that occur in the area. Moreover, the foundation walls have resistivity values that fall into the range of fractured limestone or limestone blocks. A step-wise or inclined foundation wall style has not been indicated through the parallel resistivity profiles. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Assessment of vegetation effects on hydraulics and of feedbacks on plant survival and zonation in ephemeral channels

HYDROLOGICAL PROCESSES, Issue 6 2010
P. J. Sandercock
Abstract The interaction of vegetation and flow in channels is important for understanding the influences of forces in channels and effects on erosion, sediment flux and deposition; it has implications for channel habitats, channel instability and restoration schemes. Methods are needed for calculating forces on plants and data are required on thresholds for plant destruction and survival. A simple method of calculating the effect of hydraulics on vegetation and its zonation within ephemeral channels is described. Detailed cross section surveys of channel morphology, vegetation and estimates of Manning's n are input into the software program WinXSPRO to calculate the hydraulics of flows across the channel for a given event or flow level, incorporating subdivision into zones of differing morphology and vegetation across the section. This was applied to a number of cross sections on ephemeral channels in SE Spain and typical roughness values for Mediterranean vegetation types in channels were assessed. The method is demonstrated with reference to two well-documented floods in SE Spain, in September 1997 on the Torrealvilla and in October 2003 along the Salada. These flows led to the mortality of herbs, reed and smaller shrub species. Some damage to larger shrubs and trees occurred, but trees such as Tamarisk (Tamarix canariensis) were shown to withstand high forces. Some grasses were highly resistant to removal and induced sedimentation. Significant erosion was limited to areas with little vegetation covering the channel floor. Further quantification of resistance of vegetation to flows and upper threshold values for removal is continuing by relating calculated hydraulic conditions using the methods outlined to measurements of vegetation responses in events at monitoring sites. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Efficacy of a nature-like bypass channel in a Portuguese lowland river

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2005
J. M. Santos
Summary Throughout Europe in the last decade there has been a steady shift away from more technical fish pass designs to more nature-like passes, such as nature-like bypass channels. Upstream fish passage in a nature-like bypass channel was investigated in a lowland river, the Lima River, for 117 days from March 2000 to May 2002. Fish passage was recorded using an automatic video recording system. Electrofishing samples within the bypass and below the weir were compared with species abundance found on the tape recordings. More than 7500 individuals of eight species passed through the bypass channel. Species composition was dominated by striped mullet (65.3%) and potamodromous species (34.3%), which used the bypass mainly at night. Of the environmental variables considered, bypass discharge explained most of the variation in the number of cyprinids, whereas water temperature was more important for diadromous species. Comparing species composition below the weir using passage recordings provided a useful tool to assess species efficacy of the bypass, although biological requirements should also be taken into account. This study proved the efficacy of the bypass for passage of almost all occurring species and life stages and also for providing suitable habitat for fish fauna, highlighting the use of these facilities for river restoration schemes. [source]