A Powerful Optimization Approach for the Multi Channel Dissemination Networks

In the wireless environment, dissemination techniques may improve data access for the users. In this paper, we show a description of dissemination architecture that fits the overall telecommunication network. This architecture is designed to provide efficient data access and power saving for the mobile units. A concurrency control approach, MCD, is suggested for data consistency and conflict checking. A performance study shows that the power consumption, space overhead, and response time associated with MCD is far less than other previous techniques.Comment: 9 Pages, IJCNC Journal 201

Geophysical Investigations on the Najd Fault System

The Najd fault system (NFS) extends across the Arabian Shield from NW to SE and is considered to be one of the world's largest recognized Proterozoic transcurrent fault zone, exceeding 1100 kIn in length and approximately 350 k.1J1 wide insofar as it is exposed within the Arabian Shield. Interpretation of gravity and magnetic data indicates that the Najd shearing domain extends beyond the exposed Arabian Shield into the whole Arabian plate. The shear movement diminishes towards the northwest due to splaying of the shear strands along the N-S Nabitah weakness planes. Between these major shear zones, some sinistral translation planes are common associated with S-shaped drags of the N-S Nabitah fabric. This study indicates a tectonic escape model is most probable origin fur the Najd fault system. Potential field data were comprehensively used to map the tectonic fabric of the Arabian Shield and the extension of the fault systems beneath the Phanerozoic cover, enabling a better understanding of basement evolution. In addition, ten gravity profiles with detailed GPS levelling were also acquired the field and used to model the Najd fault system. The numerous sets of magnetic and gravity surveys, the time span between them and their varying specification made the integration of these surveys very intricate. On a regional scale, the surveys were merged to form a new seamless high-resolution data set, showing more detailed features of the Arabian Shield and the Cover Rocks than any of the existing compilations. The use of potential field, geological and geochronological data, integrated within a GIS (ArcGISFM environment, has helped to obtain a better understanding of the Precambrian development of the Arabian Shield. IVEThOS - Electronic Theses Online ServiceGBUnited Kingdo

Implementation of a rigorous least-squares modification of Stokes formula to compute a gravimetric geoid model over Saudi Arabia (SAGEO13)

A precise gravimetric geoid model (SAGEO13) is computed for the Kingdom of Saudi Arabia using a rigorous stochastic computational method. The computational methodology is based on a combination of least-squares (LS) modification of Stokes formula and the additive corrections for topographic, ellipsoidal, atmospheric and downward continuation effects on the geoid solution. In this study, we used the terrestrial gravity data, digital elevation model (SRTM3) and seven geopotential models (GGMs) to compute the a new geoid model for Saudi Arabia. The least-squares coefficients are derived based on the optimisation of the input modification parameters. The gravimetric solution and its additive corrections are computed based on the optimum LS coefficients. Comparing to GPS-levelling data, SAGEO13 shows a fit of 18 cm (RMS) after using the 4-parameter fitting model.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

A humanistic approach to educational planning: Understanding user needs in elementary school buildings in Riyadh, Saudi Arabia.

Since universal education was adopted in Saudi Arabia in 1932, the Ministry of Education has been challenged to build new facilities while replacing rented and deteriorated ones for its rapidly expanding population. The sudden increase in oil revenues in the early 1970s enabled construction of massive numbers of schools, however little emphasis was placed on providing a stimulating learning environment, or on meeting specific programmatic and climatic needs. As a contribution towards improving building efficiency as well as user satisfaction, this study combines quantitative and qualitative methods to document the physical and psychological needs of students, teachers, and principals; and to recognize the bureaucratic obstacles encountered by policy makers, architects, and other educational officials. A questionnaire survey of one-third of the elementary school principals in Riyadh, preceded by a pilot study of three standardized models built in different eras, yielded the availability and condition of buildings, outdoor areas, furnishings; and the principals' general satisfaction with the latter. Subsequently an indepth qualitative study was conducted involving four elementary schools representing the typical public schools in the city. Study participants included children, teachers, and principals who were interviewed and observed using their buildings over a three-month period. This investigation revealed a number of themes including classroom overcrowding and lack of equipment, poor mechanical services, inadequate play areas, lack of communal spaces as well as substandard construction leading to costly maintenance problems. Finally school planners, architects, and maintenance officials were interviewed who pointed out severe shortages in labor and tools, budgetary constraints, overwork, lack of experienced supervisors, and pressures to meet construction schedules. Recommendations call for improved comprehensive planning of facilities involving coordination with all development agencies, increased support for construction and maintenance supervisors, involvement of local consultants, and participation of users in specifying buildings that are suited to local conditions and anticipate future needs. Future research should investigate the relationship between student performance, pedagogy, and building design in Saudi Arabia; innovative methods of user-involvement; new standardized components and construction techniques as well as ways to improve communication among all agencies involved in education.Arch.Dr.ArchitectureUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103021/1/9303675.pdfDescription of 9303675.pdf : Restricted to UM users only

Weakened continental lithosphere beneath the northern Red Sea inferred from elastic thickness

Abstract The northern Red Sea (NRS) is considered an extended continental region that has resulted in a rift system. Gravity and bathymetry data were used to estimate the Moho depth and the elastic thickness Te of the lithosphere beneath the NRS region to characterize its flexural rigidity and understand its mechanical behavior. Focusing on the Mabahiss Deep in NRS, we analyzed the lithosphere's flexural rigidity. The observed long-wavelength positive Bouguer anomaly is attributed to crustal thinning and lithospheric mantle uplift. The crustal thickness varies from 28 km in coastal areas to 24 km beneath the axial rift, supporting a regional compensation model over the Airy model. Forward modeling suggests that the optimal model explaining the regional Bouguer anomaly is a flexural model with Te equal to 7 km, indicating a weak and irregular continental crust. The primary factor contributing to this weakness is heating activity. Given the weakened state of the crust and the ongoing extension in the region, the NRS rift could evolve into a rupture, potentially leading to the formation of oceanic crust

Water exploration using Magnetotelluric and gravity data analysis; Wadi Nisah, Riyadh, Saudi Arabia

Saudi Arabia is a desert country with no permanent rivers or lakes and very little rainfall. Ground water aquifers are the major source of water in Saudi Arabia. In the Riyadh region, several Wadies including Wadi Nisah store about 14 × 106 m3 of water, which is extracted for local irrigation purposes. In such areas, the water wells are as shallow as 200–300 m in depth. The importance of Wadi Nisah is because the subsurface water aquifers that are present there could support the region for many years as a water resource. Accordingly, in this study, we performed a Magnetotelluric survey using a portable broadband sounding system (MT24/LF) to evaluate the ground water aquifer at great depths. We collected 10 broadband Magnetotelluric sounding stations (1 station/day) with an interval of about 2–3 km reaching a profile length of about 25–30 km along Wadi Nisah. Additionally, we used available gravity data to image the subsurface structure containing the aquifer. MT results indicated a low resistivity layer, associated with alluvium deposits, which was defined at a depth of about 1–2 km and extended horizontally about 15 km. Gravity data analysis was used to model this resistivity layer indicating a basement surface at 3–4 km depth