Knowledge-based Intelligent Tutoring System for Teaching Mongo Database

Recently, Intelligent Tutoring Systems (ITS) got much attention from researchers even though ITS educational technology began in the late 1960s and ITS is just embryonic from laboratories into the field. In this paper we outline an intelligent tutoring system for teaching basics of the databases system called (MDB). The MDB was built as education system by using the authoring tool (ITSB). MDB contains learning materials as a group of lessons for beginner level which include relational database system and lessons in the process to install and set up a database. MDB system has exams for each level of the Lessons. An evaluation was done to see the effectiveness the MDB among learners and instructors. The outcome of the evaluation was promising

Seismic behavior of composite bridge columns

“This study investigates experimentally and numerically the seismic behavior of large-scale hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) innovative bridge columns as a sustainable approach to endure and rapidly recover from natural disasters such as earthquakes. The HC-FCS column consisted of a concrete shell sandwiched between an outer fiber-reinforced polymer (GFRP) tube and an inner steel tube to provided continuous confinement for the concrete shell along with the height of the column. The columns have a slender inner steel tube with diameter-to-thickness (Ds/ts) ratios ranged between 85 to 254. Each steel tube was embedded into the footing, while the GFRP tube was not embedded into the footing. The HC-FCS columns having a high Ds/ts ratio of 147 and 254 with short embedded length (1.25 Ds) do not dissipate high levels of energy and display nonlinear elastic performance due to severe steel tube buckling and slippage. However, the column with a Ds/ts ratio of 85 combined with substantial embedment length (1.6 Ds) results in a nonlinear inelastic behavior, high-energy dissipation, and ductile behavior. A retrofitting technique for a high Ds/ts ratio HC-FCS column precluding buckling of the inner steel tube was proposed, examined, and approved to be effective. New bond-slip expressions were proposed based on the analytical solution to capture the bond-slip effect between steel and concrete accurately. New design guidelines were proposed for HC-FCS columns in flexural and shear, as well as the column-to-footing connection. The innovative column approved to be easy to construct and repaired with high strength, drift, and resilience connection compared to the conventional bridge columns”--Abstract, page iv

Seismic Performance of Hollow-Core Composite Columns under Cyclic Loading

This paper experimentally investigates the seismic behavior of a large-scale, hollow-core, fiber-reinforced, polymerconcrete- steel HC-FCS column under cyclic loading. The typical precast HC-FCS member consists of a concrete wall sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner steel tube. The FRP tube provides continuous confinement for the concrete wall, along the height of the column. The column is inserted into the footing and temporarily supported; then, the footing is cast in place around the column. The seismic performance of the precast HC-FCS columns was assessed and compared with previous experimental work. The compared column had the same geometric properties; but the steel tube was 25% thicker than the column that was tested in this study. This paper revealed that these HC-FCS column assemblies were deemed satisfactory by developing the whole performance of such columns and using that performance to provide excellent ductility with inelastic deformation capacity by alleviating the damage at high lateral drifts

Behavior of Hollow-Core Composite Bridge Columns having Slender Inner Steel Tubes

This paper experimentally investigates the seismic behavior of three large-scale hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) columns. An HC-FCS column consisted of a concrete shell sandwiched between an outer glass fiber-reinforced polymer (GFRP) tube and an inner steel tube. Both tubes provided continuous confinement for the concrete shell along with the height of the column. The columns had two different steel tube diameter-to-thickness (Ds/ts) ratios of 85, and 254. Each steel tube was embedded into the footing, with an embedded length of 1.25-1.6 times its diameter, while the GFRP tube was not embedded into the footing. Two columns were tested as as-built specimens. Then, one of these columns was repaired and re-tested. This study revealed that HC-FCS columns having a high Ds/ts ratio of 254 and short embedded length (1.25 Ds) do not dissipate high levels of energy and display nonlinear elastic performance due to severe steel tube buckling and slippage. However, the column with a Ds/ts ratio of 85 combined with substantial embedment length (1.6 Ds) results in a nonlinear inelastic behavior, high-energy dissipation, and ductile behavior. A retrofitting technique for a high Ds/ts ratio HC-FCS column precluding buckling of the inner steel tube was proposed and examined. The retrofitting method was characterized by the use of an anchorage system with steel tube concrete filling at the joint interface region. The retrofitted column achieved the ductile behavior and performed well under seismic loading with flexural strength increased by 22%. However, the lateral displacement capacity decreased by 26% compared to the original column due to the residual deformations and stresses exhibited during the previous test

Stability Of Thin Liquid Film Under Effect Of Apolar And Electrostatic Forces On A Horizontal Plane

The understanding of stability, dynamics and morphology of supported th (<100nm) liquid films and nanodrops are important in phenomena like flotation, adhesion of fluid particles to surfaces, kinetics and thermodynamics of precursor films in wetting, heterogeneous nucleation, film boiIing/condensation, multilayer adsorption/film pressure, instability of biological films/membranes, and many other areas While the wetting of surface by large drops is relatively well understood, wetting charactenstics of nanodrops and films have not been extensively studied in some applications like trickle bed reactors, thick coating, contact equipment for heat and mass transfer. and the like Factors that would affect the total free excess energy (per unit area) of a thin film on a substrate include the film thickness, as well as the apolar and electrostatic spreading coefficients for the system. The dynamics of the liquid film is formulated using the Navier-Stokes equations augmented by a body forces describing the apolar and electrostatic interactions

Seismic Performance of Hollow-Core HC-FCS Columns having Inner Steel Tube with High Diameter to Thickness Ratio

This paper experimentally investigates the seismic behavior of a large-scale hollow-core fiber-reinforced polymer-concrete-steel HC-FCS column under seismic cyclic loading. The HC-FCS column consisted of a concrete shell sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner steel tube. The FRP tube provides continuous confinement for the concrete shell along the height of the column while the steel tube provides the required flexural strength. The tested column has an inner steel tube that had a diameter-to-thickness ratio (Di/t) (of 254. The seismic performance of the precast HC-FCS column was compared to that of HC-FCS column having(Di/t) of 64. Three-dimensional numerical models were also developed using LS_DYNA software for modeling the HC-FCS columns. This study revealed that HC-FCS columns having very high (Di/t) and short embedded lengths do not dissipate high levels of energy and display nonlinear elastic performance due to steel tube slippage. However, the use of small values of (Di/t)combined with generous embedment length results in a nonlinear inelastic behavior, high energy dissipation, and ductile behavior

Inelastic Response Evaluation of Precast Composite Columns under Seismic Loads

This paper presents a non-linear finite element analysis of large-scale hollow-core fiber-reinforced polymer-concrete-thin walled steel (HC-FCS) precast columns under reversed cyclic loading. The HC-FCS columns provide an economical and efficient alternative to conventional concrete bridge columns. The precast HC-FCS column consists of a concrete shell sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner thin-walled steel tube. The steel tube diameter-to thickness (Di/ts) ratio was 254. The proposed FEA model was developed using LS_DYNA multipurpose software and was verified by experimental results performed in this study. The FE model was used to investigate some important phenomena such as thin-walled steel tube cyclic local buckling and to determine where and when steel tube yielding and damage initiation occurs. The comparison and analysis of the proposed model to predict local damages, failure patterns, and hysteretic curves were in reasonable accuracy with the experimental outcomes

Features Ranking Techniques for Single Nucleotide Polymorphism Data

Identifying biomarkers like single nucleotide polymorphisms (SNPs) is an important topic in biomedical applications. Such SNPs can be associated with an individual’s metabolism of drugs, which make these SNPs targets for drug therapy, and useful in personalized medicine applications. Yet another important application is that SNPs can be associated with an individual’s genetic predisposition to develop a disease. Identifying these associations allow proactive steps to be taken to hinder, delay or eliminate the disease. However, the problem is challenging; data are high dimensional and incomplete, and features (SNPs) are correlated. The goal of this thesis is to propose features ranking methods to reduce the number of selected features and the computational cost required to select these features in a binary classification task. The main idea of the hypothesis is that specific values within a feature might be useful in predicting specific classes, while other values are not. In this context, three heuristic methods are applied to select the best features. The methods are applied to the Wellcome Trust Case Control Consortium (WTCCC1) dataset, and evaluated on Texas A&M University Qatar’s High Performance Computing platform. The results show that the classification accuracy achieved by the proposed methods is comparable to the baseline. However, one of the proposed methods reduced the execution time of the feature selection and the number of features required to achieve similar accuracy in the baseline by 40% and 47% respectively

Nonlinear Analysis of Hollow-Core Composite Building Columns

This paper numerically investigates the behavior of hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) building columns under combined axial compression and flexural loadings. The HC-FCS column for buildings consists of an outer circular fiber-reinforced polymer (FRP) tube, an inner square steel tube, and a concrete wall between them. A three-dimensional numerical model has been developed using LS_DYNA software for modeling of large scale HC-FCS columns. The nonlinear FE models were designed and validated against experimental results gathered from HC-FCS columns tested under cyclic lateral loading. The FE results were in decent agreement with the experimental backbone curves. These models subsequently were used to conduct a parametric study investigating the effects of the concrete wall thickness, steel tube width-to-thickness (B/t) ratio, and local buckling instability on the behavior of the HC-FCS columns. The obtained local buckling stresses results from the FE models were compared with the values calculated from the empirical equations of the available design codes. Finally, an approximated expression based on the available empirical formulas and the FE model results has been proposed in this paper to calculate the local buckling stresses of HC-FCS columns