Improvement of Concrete Properties and Reinforcing Steel Inhibition Using a Natural Product Admixture

The use of a natural white juice, taken from magrabe banana stem, as concrete admixture to improve mechanical and physicrvchemical properties of concrete has been studied. The compressive strength, bulk density the free lime liberated during hydration and the combined water content were determined. The results indicate that the admixture acts as a retarder in most cases and as accelerator in some ones. Also, the admixture effect on the corrosion resistance of the reinforcing steel against surrounding aggressive media has been investigated using galvanostatic polarization technique. The addition of 0.2% admixture leads to the more inhibition of the steel     

A Video Server cost/performance Estimator tool

The Video Server Estimator (VSE) is an analytical tool which allows a user to perform a cost/performance analysis of video servers with hierarchical storage. The underlying model comprises multiple systems, main memory, expanded storage, disks and a tape library. The main objective of the tool is to optimally allocate the video files to different storage media based on the system parameters and the video file request probability distribution. The cost and the size of the video server that can accommodate a customer profile are determined. Furthermore, the impact of design parameters on the cost and performance are examined through a parametric analysis.     

Photo-Thermal-Elastic Interaction in a Functionally Graded Material (FGM) and Magnetic Field

Silicon - In this work, we aim to investigate the photo-thermal-elastic waves interaction in a nano-composite semiconductor, elastic and functionally graded material (FGM). The governing equations...     

Measurements of the suitability of large rock salt formations for radio detection of high-energy neutrinos

We have investigated the possibility that large rock salt formations might be suitable as target masses for detection of neutrinos of energies about 10 PeV and above. In neutrino interactions at these energies, the secondary electromagnetic cascade produces a coherent radio pulse well above ambient thermal noise via the Askaryan effect. We describe measurements of radio-frequency attenuation lengths and ambient thermal noise in two salt formations. Measurements in the Waste Isolation Pilot Plant, located in an evaporite salt bed in Carlsbad, NM yielded short attenuation lengths, 3–7 m over 150–300 MHz. However, measurements at United Salt's Hockley mine, located in a salt dome near Houston, Texas yielded attenuation lengths in excess of 250 m at similar frequencies. We have also analyzed early ground-penetrating radar data at Hockley mine and have found additional evidence for attenuation lengths in excess of several hundred meters at 440 MHz. We conclude that salt domes, which may individually contain several hundred cubic kilometer water-equivalent mass, provide attractive sites for next-generation high-energy neutrino detectors.     

Making a cost-effective video server

A cost-effective system must allocate video files to the right place at the right time. We present the characteristics of different storage media and provide an analytical model for obtaining the cost of storing video files. We then state the video file allocation problem and provide a solution     

Propagation of the photothermal waves in a semiconducting medium under L-S theory

The model of the equations of generalized thermoelasticity based on the Lord–Shulman theory with one relaxation time is used to study the photothermal waves in a semiconducting medium. The exact expressions for the displacement components, temperature, carrier density, and stress components are obtained using normal mode analysis. Numerically simulated results are obtained and presented graphically for silicon to depict the effect of time parameter on the different physical quantities.     

Photothermal Excitation Process during Hyperbolic Two-Temperature Theory for Magneto-Thermo-Elastic Semiconducting Medium

Silicon - A novel technique is used to study the magnetic field influence in the free surface of an elastic semiconductor medium for a one-dimensional (1D) deformation. The problem is formulated...     

Interpretation of multifrequency complex resistivity data for alayered Earth model

A method is proposed for interpreting data obtained by measuring mutual impedances of dipole-dipole configurations on the surface of a layered Earth. Such data are assumed to be available over a sufficiently broad band of temporal frequencies and dipoles interspacing. For a given grounded transmitting dipole, two receiving grounded dipoles of selected different orientations are used. The electromagnetic circuit coupling is effectively cancelled at any given frequency by appropriate Bessel transform operation on the measured complex impedances versus spacing. The next step is to infer the complex resistivities of the Earth's layers at each frequency. From such inferred data at a sufficient number of spot frequencies, the dispersive behavior of the resistivity of each layer is deduced. This proposed procedure is demonstrated by applying it to computer-simulated data on a two-layer Earth with encouraging results     

Extreme scale computing: Modeling the impact of system noise in multi-core clustered systems

System noise or Jitter is the activity of hardware, firmware, operating system, runtime system, and management software events. It is shown to disproportionately impact application performance in current generation large-scale clustered systems running general-purpose operating systems (GPOS). Jitter mitigation techniques such as co-scheduling jitter events across operating systems improve application performance but their effectiveness on future petascale systems is unknown. To understand if existing jitter mitigation solutions enable scalable petascale performance, we construct two complementary jitter models based on detailed analysis of system noise from the nodes of a large-scale system running a GPOS. We validate these two models using experimental data from a system consisting of 256 GPOS instances with 8192 CPUs. Based on our models, we project a minimum slowdown of 1.8%, 4.1%, and 6.5% for applications executing on a similar one petaflop system running 1024 GPOS instances and having global synchronization operations once every 100 ms, 10 ms, and 1 ms, respectively. Our projections indicate that–although existing mitigation solutions enable scalable petascale performance–additional techniques are required to contain the impact of jitter on multi-petaflop systems, especially for tightly synchronized applications.     

High-power comparison among brazed, clamped and electroformed X-band cavities

We report the building procedure of X-band copper structures using the electroforming and electroplating techniques. These techniques allow the deposition of copper layers on a suitable die and they can be used to build RF structures avoiding the high temperature brazing step in the standard technique. We show the constructed prototypes and low power RF measurements and discuss the results of the high power tests at SLAC National Accelerator Laboratory.