mahmoud taha

This study proposes a framework to develop an effective reliability-based model and management system for the corrosion dynamics in the corrosiondamaged reinforced concrete that relates the corrosion process with the corrosion precursors from the environment and inherent to the material with time. The proposed framework will be tied to a reliability-based service life prediction model of reinforced concrete structures where corrosion is detected and the uncertainties inherent within its influencing parameters are quantified. The quantified uncertainties in the parameters that influence the corrosion process will be used to calibrate design factors used in structural design for repair and load rating of corroding reinforced concrete structures using reliability-based service life prediction models. The developed model will conform with inspection practices and reliability concepts by Department of Transportation (DOT) to facilitate implementing the research results into the DOT Integ...

Extraction parameters, chemical fingerprint, and the single compounds' activity levels were considered for the selection of active botanicals. For an initial survey, the total bioactivity (i.e., total reducing capacity, total flavonoids contents and free radical scavenging capacity) of 21 aqueous and 21 ethanolic plant extracts was investigated. Ethanolic extracts showed a higher yield and were further analyzed by HPTLC in detail to obtain fingerprints of single flavonoids and further bioactive components. Exemplarily shown for turmeric (Curcuma longa) and milk thistle (Silybum marianum), effect-directed analysis (EDA) was performed using three selected (bio)assays, the Aliivibrio fischeri bioassay, the Bacillus subtilis bioassay and the 2,2-diphenyl-1-picrylhydrazyl (DPPH*) assay. As a proof of principle, the bioactive components found in the extracts were confirmed by HPTLC-MS. Bioassays in combination with planar chromatography directly linked to the known, single effective c...

ABSTRACT a b s t r a c t Synthetic calcium silicate hydrate (C–S–H) made with calcium to silicate (C/S) mixture ratios of 0.9, 1.2 and 1.5 respectively is characterized. C–S–H was produced by extracting calcium oxide (CaO) from cal-cium carbonate (CaCO 3) and then mixing it with micro-silica (SiO 2) and deionized water to make slurry. The slurry was continuously mixed for 7 days, then the excess water was removed and thermo gravimet-ric analysis (TGA) was conducted. The drying method was equilibrated to 11% relative humidity (RH). The stoichiometric formula of the synthetic C–S–H were approximated as C 0.7 SH 0.6 , C 1.0 SH 0.8 and C 1.2 SH 2.4 for C/S mixture ratios of 0.9, 1.2 and 1.5 respectively. The dried powders were characterized using X-ray dif-fraction analysis (XRDA), and 29 Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spec-troscopy. The powders were also compacted with 95 MPa pressure and nanoindentation of the compacted specimens were then undergone to mechanically characterize the synthetic C–S–H. The experiments provide insight on the nanoscale mechanical characteristics of C–S–H.

Concrete cracking strength can be defined as the tensile strength of concrete subjected to pure tension stress. However, as it is difficult to apply direct tension load to concrete specimens, concrete cracking is usually quantified by the modulus of rupture for flexural members. In this study, a new direct tension test setup for cylindrical specimens (101.6 mm in diameter and 203.2 mm in height) similar to those used in compression test is developed. Double steel plates are used to obtain uniform stress distributions. Finite element analysis for the proposed test setup is conducted. The uniformity of the stress distribution along the cylindrical specimen is examined and compared with rectangular cross section. Fuzzy image pattern recognition method is used to assess stress uniformity along the specimen. Moreover, the probability of cracking at different locations along the specimen is evaluated using probabilistic finite element analysis. The experimental and numerical results of th...

Endovascular stenting is an alternative treatment for brachiocephalic artery stenosis, replacing standard surgical approaches such as carotid endarterectomy. However, a percutaneous approach may be difficult because various conditions such as severe arteriosclerosis of iliac or femoral arteries and aortic disease. We report our experience with intraoperative stenting for these lesions, presenting indications, strategy, and results. Seven patients underwent intraoperative stent placement via an open cervical approach. The sites of lesions included 1 innominate artery, 1 common carotid artery, and 5 cervical carotid arteries. Stenting was performed with a sheath introducer placed through a surgically exposed common carotid artery via a small skin incision or common carotid artery exposed for simultaneously performed carotid endarterectomy. Distal protection was used in 6 patients with an endovascular protective balloon or external clamping with forceps. Sufficient dilation of stenosis was obtained in all cases. No complications such as transient ischemic attack, cerebral infarction, and hyperperfusion were encountered. Wound hematoma was not experienced despite perioperative antiplatelet therapy and heparinization during the procedure. Angiographic follow-up over 1 year showed no restenosis in 5 available patients. Intraoperative stenting may be an excellent alternative for patients in whom both direct surgical approach and standard percutaneous endovascular approach are not possible.

Abstract – Structural damage occurs due to structural overloading or due to environmental conditions or combined effects. Extensive research on structural health monitoring, damage diagnosis and damage pattern recognition have been developed over the last two decades. Recently, ...

River flow forecasting is an essential procedure that is necessary for proper reservoir operation. Accurate forecasting results in good control of water availability, refined operation of reservoirs and improved hydropower generation. Therefore, it becomes crucial to develop forecasting models for river inflow. Several approaches have been proposed over the past few years based on stochastic modeling or artificial intelligence (AI) techniques. In this article, an adaptive neuro-fuzzy inference system (ANFIS) model is proposed to forecast the inflow for the Nile River at Aswan High Dam (AHD) on monthly basis. A major advantage of the fuzzy system is its ability to deal with imprecision and vagueness in inflow database. The ANFIS model divides the input space into fuzzy sub-spaces and maps the output using a set of linear functions. A historical database of monthly inflows at AHD recorded over the past 130 years is used to train the ANFIS model and test its performance. The performance of the ANFIS model is compared to a recently developed artificial neural networks (ANN) model. The results show that the ANFIS model was capable of providing higher inflow forecasting accuracy specially at extreme inflow events compared with that of the ANN model. It is concluded that the ANFIS model can be quite beneficial in water management of Lake Nasser reservoir at AHD.

The last two decades have shown an increasing trend in the use of positioning and navigation technologies in land vehicles. Most of the present navigation systems incorporate global positioning system (GPS) and inertial navigation system (INS), which are integrated using Kalman ...

Most of the present vehicular navigation systems rely on global positioning system (GPS) combined with inertial navigation system (INS) for reliable determination of the vehicle position and heading. Integrating both systems provide several advantages and eliminate their individual shortcomings. Kalman filter (KF) has been widely used to fuse data from both systems. However, KF-based integration techniques suffer from several limitations related to its immunity to noise, observability and the necessity of accurate stochastic models of sensor random errors. This article investigates the potential use of adaptive neuro-fuzzy inference system (ANFIS) for temporal integration of INS/GPS in vehicular navigation. An ANFIS-based module named “P–δP” is designed, developed, implemented and tested for fusing INS and GPS position information. The fusion process aims at providing continuous correction of INS position to prevent its long-term growth using GPS position updates. In addition, it provides reliable prediction of the vehicle position during GPS outages. The P–δP module was examined using real navigation system data compromising an Ashtech Z12 GPS receiver and a Honeywell LRF-III INS. The proposed module proved to be successful as a modeless and platform independent module that does not require a priori knowledge of the navigation equipment utilized. Limitations of the ANFIS module are also discussed.

This paper presents the results of experimental and analytical investigations of the long-term behavior of the epoxy used at the concrete–FRP interfaces. Double shear long-term test was performed on specimens composed of concrete blocks bonded to FRP sheets using ...

ABSTRACT Numerical analysis using a finite-element model was performed to simulate and investigate the long-term behavior of two RC beams with similar steel reinforcement, cast from the same batch of concrete. One beam was a plain RC beam and the other beam was strengthened using carbon fiber-reinforced polymer (FRP) strips. The deflections of both beams have been monitored for 5 years after loading. The finite-element model included both creep of concrete and viscoelasticity of the epoxy adhesive at the concrete-carbon FRP (CFRP) interface. The results of the finite-element analysis are compared to experimental observations of the two beams. The finite-element analysis was found to be able to simulate the long-term behavior of the CFRP-strengthened beam and help us understand the complex changes in the stress state that occur over time.