Preconstruction solution for Groundwater rise in Sabkha

Sabkha deposits are formed under arid conditions and are considered as a common problematic soil along the coastal area of the Arabian Gulf. Saudi Arabia. One of the most serious problems associated with the coustruction on sabkha is the rise of groundwater level causing settlement and hence imposing additional stress on the structural elements. Groundwater rise in sabkha was attributed to numerous reasons; the interruption of the natural evaporation by construction is considered to the most prominent. The evaporation data along the Arabian Gulf coast had been analyzed and the possible rise in the groundwater level had been predicted using both the evaporation and soil porosity data. A horizontal drain is suggested to interrupt the capillarity in the soil and to drain the infiltrating water and hence stop the groundwater rise. A mathematical model for the optimum selection of the drain characteristics is presented. This model requires the knowledge of some site conditions such as the area to be drained, the thickness of the aquifer and the soil coefficient of permeability. Based on these values a design curve can be constructed to relate the horizontal drain characteristics such as the longitudinal transmissivity of the drain, its thickness and its slope. An example using the parameters of a specific site conditions along the Arabian Gulf coast is given to present the suggested design curve. The relative significance of these parameters on the drain characteristics and geometry is also discussed.     

Simplified model for estimating the punching resistance of reinforced corete slabs

A method for predicting the punching strength of symmetric slab—column connections in flat slab structures is presented. The rational simplified model used was derived from a more complete one previously proposed by the author. This model leads to a single equation which is all that is required for design, agrees with the observed slab behaviour and correlates well with test results.     

Kaolin modified with new resin–iron chelate as flame retardant system for polypropylene

Polypropylene's fire‐retardant properties can be improved by using modified kaolin. Modification was done by reaction of kaolin with a prepared resin–iron chelate. Polypropylene samples were loaded with different amounts of kaolin, modified kaolin, and their mixture. Ignition properties of the produced samples were evaluated using cone calorimeter, UL 94, and thermogravimetric analysis techniques. It was found that sample S2 loaded with a mixture of kaolin and modified kaolin had significantly reduced the smoke generation and had a heat release rate comparable to that with kaolin. It was also found that samples S4 and S5 loaded with modified kaolin burned out earlier than did the other samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3119–3125, 2004     

A study on Geotrichum candidum lipase stability

The lipolytic activity of Geotrichum candidum supernatant was determined before and after storage at various temperatures. The storage stability at 37°C decreased with increasing age of the culture, the activity of a 10 days old culture disappeared after 20 h. Heat treatments at 80°C for 10 min increased the storage stability of the lipase from older cultures. Mixing the supernatants of the old and young cultures revealed the existence of a transferable factor, associated with the crude lipase and more abundant in older cultures. The results support the hypothesis of the inactivation of the lipase by coexisting proteases.     

Robust hybrid watermarking techniques for different color imaging systems

Multimedia Tools and Applications - Digital watermarking is an efficient and promising mechanism for protecting the copyright of the transmitted multimedia information. Thus, this paper presents...     

Using thermal analysis techniques for identifying the flash point temperatures of some lubricant and base oils

The flash point (FP) temperatures of some lubricant and base oils were measured according to ASTM D92 and ASTM D93. In addition, the thermal stability of the oils was studied using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The DSC results showed that the FP temperatures, for each oil, were found during the first decomposition step and the temperature at the peak of the first decomposition step was usually higher than FP temperatures. The TGA results indicated that the temperature at which 17.5% weigh loss take placed (T_17.5%) was nearly identical with the FP temperature (±10 °C) that was measured according to ASTM D92. The deviation percentage between FP and T_17.5% was in the range from ?0.8% to 3.6%.     

Insight into the Electrochemical and Semiconducting Properties of Native Oxide Films on Ti Metal and Its Ti–6Al–4V Alloy in Borate Buffer Solutions

Protection of Metals and Physical Chemistry of Surfaces - Titanium and titanium alloys are intriguing materials having widespread industrial and medical applications due to their excellent...     

Cu and Ag Nanoparticles Films Deposited on Glass Substrate Using Cold Cathode Ion Source

Structural, electrical and optical properties of Cu and Ag nanoparticles thin films deposited on glass substrates prepared by sputtering were investigated. Cold cathode ion source used for sputtered of copper and silver targets to deposit nanoparticles thin films on glass substrate using argon gas. X-ray diffraction was used to study the structure and the grain size of thin film which reveals that average grain size is in nano region. Copper nanoparticles was in rang 14 nm and silver nanoparticles size was 20 nm in first peak using Scherrer’s method. The electrical resistivities of copper and silver thin films were also investigated. The thin film resistance Rs of Cu and Ag equals 1.33 and 6.35 Ω respectively. I-V characteristics of thin films were recorded at room temperature and are found to be linear. Optical properties of the synthesized materials are studied by UV–Vis in the wavelength range 200–800 nm. The calculated band gap for the Cu thin film on glass are estimated to be E_gCu = 2.18 eV.     

Solution blow spinning of piezoelectric nanofiber mat for detecting mechanical and acoustic signals

Solution blow spinning (SBS) technique can produce nanofibers (NFs) mat in large-scale production. In this work, the SBS was used to fabricate piezoelectric polyvinylidene fluoride (PVDF) NF membranes that can be utilized for energy harvesting applications. The effect of operating air pressure from (2–5 bar) on the surface morphology of the NFs has been studied. The structural analysis for crystalline polymorph β-phase for PVDF powder, casted film, electrospinning and SBS NFs has also been presented with the aid of Fourier-transform infrared spectroscopy and X-ray diffraction (XRD). Piezoelectric characteristics of PVDF NFs mats were tested by applying impact impulse with different weights from different heights between 1 and 10 cm. The sensitivity of the voltage response increased from 1.71 mV/g to 8.98 mV/g, respectively. Besides, the SBS generated PVDF mat is found to be sensitive to pressure forces in a range of few Newtons with the generated voltage according to detected sensitivity of 80 mV/N based on the analysis of the impact of a few Hertz mechanical vibrations. In addition, the produced SBS NFs were applied as an acoustic signal detector within different acoustic frequencies. The results suggest that the β-phase PVDF nanofibrous membrane produced via the SBS technique has a great potential to be used as a piezoelectric sensor.     

Fully programmable single-photon detection module for InGaAs/InP single-photon avalanche diodes with clean and sub-nanosecond gating transitions

We present the design and characterization of a modern near-infrared photon counting module, able to exploit the best performance of InGaAs/InP single-photon avalanche diodes for the detection of fast and faint optical signals up to 1.7 μm. Such instrument is suitable for many applications, thanks to the user-friendly interface and the fully adjustable settings of all operating parameters. We extensively characterized both the electronics and the detector, and we validated such instrument up to 133 MHz gate repetition frequency, for photon-counting and photon-timing applications, with very clean temporal response and excellent timing performance of less than 100 ps.