Catalyst Synthesis & Characterization for Dry Reforming of Methane: Synthesis of Ni-based Hydrotalcite Catalyst by Impregnation Method

The increased consumption and abundance of fossil fuels has led to significant greenhouse gases (GHGs) emissions, mainly CO2, which has led to health problems and climate changes. Therefore, it is essential to reduce the emissions of carbon dioxide to the atmosphere which contributes to protect our plant and the public health. Several technologies have been used in this regard such as carbon capture and utilizing it. The GTL (Gas-to-liquid) technology uses reforming units such as DRM (Dry Reforming of Methane) that utilizes COv2 to produce syngas for generating various products. Therefore, to mitigate carbon dioxide the reforming unit requires a catalyst to perform in the production of syngas by using two of the main GHGs, methane and carbon dioxide. This work is based on the synthesis of synthesizing Ni-based catalysts for DRM to produce syngas and specifically focuses on the preparation and characterization of hydrotalcite derived Mg-Al and doped Zn on Mg-Al with molar ratio of 2:1 for Mg: Al. The bimetallic supports were prepared via the co-precipitation method while metallic supports by precipitation method. The Ni-based catalysts were synthesized through the impregnation method. Furthermore, to avoid carbon deposition and sintering of the catalyst, the conducted temperature for DRM reaction was at 650 degrees C. The characterization technologies of the catalysts were performed using XRD, BET, FTIR, H2- TPR, and DRM reaction techniques to confirm the hydrotalcite structure and the metal-support interactions

Cleft Palate In Children And Adolescent: A Study Of Arch Expansion

Penggunaan alat untuk mengembangkan lelangit telah dikatakan berkesan dalam menghasilkan daya ringan yang berpanjangan untuk mengembangkan rahang maksila di kalangan pesakit-pesakit sumbing bibir dan lelangt yang mempunyai saiz maksila yang kecil. The use of palatal expansion appliances has been claimed to produce a light, continuous force, which is capable of expanding the maxilla and correcting dental arch width of cleft palate patients who have deficient maxilla

The Impact of Small Group Instruction on Preschool Literacy Skills

This study focused on 17 preschool students in a northern Jordan city. Preschoolerswere taught specific literacy skills in a small group instructional setting. The students’ skill level was assessed at the beginning and middle of the school year. The researcher’s goal was to determine if teaching literacy skills in a small group setting would improve the skill level of the preschool students. Results showed that using small groups was an effective way to increase preschool students’ literacy skill levels

An Assessment of Bullying/Victimization Behaviors among Third-Graders in Jordanian Public Schools

This study investigates the prevalence of bullying/victimization behaviors among third graders in Jordanian public schools from the perspectives of both students and their teachers. The study involved 500 third-grade students and 52 teachers who randomly selected from 20 Jordanian public schools in the first Irbid directorate schools. Results of the students’ perceptions of bullying and victims of bullying behaviors indicated a generally low amount of bullying and victims of bullying among third graders. However, teachers reported more bullying by other students than the students reported. Also, teachers in this study reported physical bullying/victims of bullying as the most frequent and verbal bullying as the least frequent. Implications for ministry of education and schools were discussed. Key words: bullying, victimization, physical, verbal, relational

Material length scales in gradient-dependent plasticity/damage and size effects: theory and computation

Structural materials display a strong size-dependence when deformed non-uniformly into the inelastic range: smaller is stronger. This effect has important implications for an increasing number of applications in structural failure, electronics, functional coatings, composites, micro-electro-mechanical systems (MEMS), nanostructured materials, micro/nanometer fabrication technologies, etc. The mechanical behavior of these applications cannot be characterized by classical (local) continuum theories because they incorporate no ‘material length scales’ and consequently predict no size effects. On the other hand, it is still not possible to perform quantum and atomistic simulations on realistic time and structures. It is therefore necessary to develop a scale-dependent continuum theory bridging the gap between the classical continuum theories and the atomistic simulations in order to be able to design the size-dependent structures of modern technology. Nonlocal rate-dependent and gradient-dependent theories of plasticity and damage are developed in this work for this purpose. We adopt a multi-scale, hierarchical thermodynamic consistent framework to construct the material constitutive relations for the scale-dependent plasticity/damage behavior. Material length scales are implicitly and explicitly introduced into the governing equations through material rate-dependency (viscosity) and coefficients of spatial higher-order gradients of one or more material state variables, respectively. The proposed framework is implemented into the commercially well-known finite element software ABAQUS. The finite element simulations of material instability problems converge to meaningful results upon further refinement of the finite element mesh, since the width of the fracture process zone (shear band) is determined by the intrinsic material length scale; while the classical continuum theories fail to address this problem. It is also shown that the proposed theory is successful for the interpretation of indentation size effects in micro/nano-hardness when using pyramidal and spherical indenters and gives sound interpretations of the size effects in micro-torsion of thin wires and micro-bending of thin beams. Future studies should be directed toward incorporation of the size effects into design procedures and code recommendations of modern engineering structures (e.g. for MEMS, NEMS, coatings, thin films), fiber composites (e.g. for aircrafts and ships), etc

Promotional Campaigns in the Era of Social Platforms

The rise of social media has facilitated the diffusion of information to more easily reach millions of users. While some users connect with friends and organically share information and opinions on social media, others have exploited these platforms to gain influence and profit through promotional campaigns and advertising. The existence of promotional campaigns contributes to the spread of misleading information, spam, and fake news. Thus, these campaigns affect the trustworthiness and reliability of social media and render it as a crowd advertising platform. This dissertation studies the existence of promotional campaigns in social media and explores different ways users and bots (i.e. automated accounts) engage in such campaigns. In this dissertation, we design a suite of detection, ranking, and mining techniques. We study user-generated reviews in online e-commerce sites, such as Google Play, to extract campaigns. We identify cooperating sets of bots and classify their interactions in social networks such as Twitter, and rank the bots based on the degree of their malevolence. Our study shows that modern online social interactions are largely modulated by promotional campaigns such as political campaigns, advertisement campaigns, and incentive-driven campaigns. We measure how these campaigns can potentially impact information consumption of millions of social media users

A finite deformation coupled plastic-damage model for simulating fracture of metal foams

Metal foams are a novel class of lightweight materials with unique mechanical, thermal, and acoustical properties. The low ductility of metal foams hinders the possibilities of applying secondary forming techniques to shape metal foam sandwich panels into desired industrial components. An important factor is the limited studies on their macroscopic damage and fracture behavior under complex loading conditions. There exist numerous mechanistic micromechanics models describing the fracture behavior of metal foams at the strut level, but very few work have been done on modeling their macroscopically coupled plasticity-damage constitutive behavior. The objective of this study is to develop a continuum finite deformation elasto-plastic-damage mechanics-based constitutive model for metal foams. The constitutive model is implemented in a user-defined material subroutine (UMAT) in the finite element software ABAQUS/Standard. The elasto-plastic part is implemented using backward-Euler return algorithm within Deshpande–Fleck constitutive framework. Continuum damage mechanics framework is formulated for the development of damage evolution equations. These damage evolution equations take into consideration the various key degradation mechanisms that lead to the macroscopic fracture of metal foams under various loading conditions. The model is calibrated and validated based on experimental data on aluminum foams under different loading paths, strain rates, and temperatures

Dynamics, Mechanistic and Equilibrium Studies for the Biosorption of Nickel on Palm Tree Leaves

Adsorption of heavy metals on biological sorbents, activated carbon and synthetic resin particles is a common separation technique. In this study, the biosorption of nickel ions from aqueous solution by palm tree leaves was investigated as a function of shaking time, nickel ions concentration and equilibrium pH. Competitive adsorption of nickel on palm tree leaves with EDTA and citric acid was also investigated. Batch adsorption experiments revealed that the biosorption of nickel on palm tree leaves was strongly pH dependent, and maximum nickel sorption was found to occur at equilibrium pH of 6.0. Dynamics studies showed that: the initial uptake of nickel on palm tree leaves was rapid, equilibrium was established within 30 minutes, and the data followed the pseudo-second order reaction. The equilibrium sorption data of nickel on palm tree leaves at solution pH 6.0 were described by two-parameter isotherm models such as the Langmuir, Freundlich, and D-R models and three-parameter models such as Redlich-Peterson and Sips isotherm models. Ion-exchange, adsorption-complexation and intraparticle diffusion mechanisms were found to be involved in the biosorption process. The Effect of ions interference on the biosorption of nickel on palm tree leaves showed that the sorption of nickel on palm tree leaves was adversely affected by the presence of chelating agents such as EDTA and citric acid

Simple speed sensorless DTC-SVM scheme for induction motor drives

The paper focuses on the development of a novel DSP based high performance speed sensorless control scheme for PWM voltage source inverter fed induction motor drives. Firstly, two generic torque and flux control methods the Field Oriented Control (FOC) and Direct Torque Control (DTC), are briefly described. For implementation the sensorless scheme DTC with Space Vector Modulation (DTCSVM) has been selected because it eliminates the disadvantages associated with the DTC while keeping the advantages of both FOC and DTC. Secondly, the simple flux vector observer allowing speed sensor elimination is given. The novelty of the presented system lays in combining the DTC-SVM structure with a simple observer for both torque/flux and speed sensorless control. Furthermore, the DTC-SVM structure which operates in speed sensorless and torque control mode is presented. Finally, the description of a 50 kW laboratory drive and experimental results illustrating properties of the system are given