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Khalid G. Al-Shdifat,Mikhled Maayah,Robert Mayo,Kenneth St. Louis 한국언어청각임상학회 2018 Communication Sciences and Disorders Vol.23 No.4
Objectives: The current study explored the attitudes of 1st, 2nd, 3rd, and 4th year students in Communication Sciences and Disorders (CSD) at Jordan University of Science and Technology (JUST) toward stuttering and people who stutter (PWS). Methods: All students in the CSD program from each year level at JUST were invited to participate in the current study. A translated Arabic version of the Public Opinion Survey of Human Attributes-Stuttering (POSHA-S), a standard instrument, was used to compare stuttering attitudes from the four classes and also to compare them to attitudes of similar students and the general population from different countries on the POSHA-S database. Results: Data collected from the CSD students at JUST did not reflect any significant change in students’ overall attitudes toward stuttering as they progressed from the 1st through the 4th year. However, they exhibited more positive attitudes than the public in Jordan. Compared to the POSHA-S database, Jordanian attitudes were somewhat less positive than most SLP students sampled in other regions. Conclusion: The current study revealed that students of CSD in Jordan hold less positive attitudes toward stuttering and PWS compared to people from other countries in the same region. Findings are discussed relevant to the literature on attitudes toward stuttering and PWS.
Khalid Quertite,Halima Zaari,Hamid Ez-Zahraouy,Abdallah El Kenz,Hamid Oughadou,Abdelilah Benyoussef 한국물리학회 2017 Current Applied Physics Vol.17 No.10
We report detailed DFT calculations and Monte Carlo simulations on the pure and doped cuprate superconductor HgBa2CuO4þd. For the pure compound (d ¼ 0), we have obtained an insulating behavior with strong antiferromagnetic copper spin correlations in the CuO2 plane. The high value of the calculated Neel temperature TN ¼ 333 K reflects the large in-plane exchange interaction J ¼ -145 meV. The obtained optical properties and critical exponents demonstrate the anisotropic quasi-2D character of this type of materials. As for the doped compound the electronic structure and the transport properties have been investigated for various values of doping. Based on these data, we suggest a prediction of the value of optimum doping for HgBa2CuO4þd (doptimal ¼ 0.125).
Two-Relay-Based Cooperative MAC Protocol for Wireless Ad hoc Networks
Khalid, Murad,Yufeng Wang,In-ho Ra,Sankar, Ravi IEEE 2011 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.60 No.7
<P>The cooperative communication approach promises improved throughput and delay performance by effective use of spatial diversity in wireless ad hoc networks. The CoopMAC I protocol proposed by Liu picks either a direct path or a relay path based on rate comparison to enhance average throughput and delay performances. However, its performance deteriorates under fading conditions due to lower direct path or relay path reliability. UtdMAC, which was proposed by Agarwal , performs better than CoopMAC I in terms of average throughput and delay performances due to improved transmission reliability provided by the backup relay path. Although it is better than CoopMAC I, UtdMAC does not fully benefit from higher throughput relay path (compared with the direct path) since it uses relay path only as a secondary backup path. In this paper, a new cooperative medium access control (MAC) protocol, which is termed the 2rcMAC protocol, is proposed for a small-sized network. The protocol makes use of two cooperating nodes to achieve superior throughput and delay performances, compared with the existing cooperative MAC protocols. The secondary relay path is invoked as a backup path for better transmission reliability and higher throughput through the relay path. Moreover, handshaking and single-bit feedbacks resolve contentions among relay nodes in proximity at the time and further provide the source node with rate information on source-to-destination, source-to-relay, and relay-to-destination links. Performance gains achieved by the 2rcMAC protocol under fast-fading conditions over the existing cooperative MAC protocols are compared and discussed. Simulation results clearly show an average throughput improvement of 7% and 25% and an average delay improvement of 94.8% and 98.9%, compared with UtdMAC and CoopMAC I, respectively.</P>
Bond characteristics of SFRP composites containing FRP core/anchors coated on geopolymer mortar
Khalid, Hammad R.,Ha, S.K.,Park, S.M.,Wang, Zhen,Lee, H.K. Elsevier 2018 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.189 No.-
<P><B>Abstract</B></P> <P>The present study investigates the bending bond characteristics of novel hybrid sprayed fiber-reinforced polymer (SFRP) composites containing fiber core/anchors. Carbon or basalt fiber cores were embedded in SFRP composites as core reinforcements, and of which their ends were inserted into the beams to act as anchors. Four-point bending bond tests were conducted to characterize the bonding behavior of these hybrid SFRP composites in terms of enhancement of the ultimate bond strength ( <SUB> τ u </SUB> ) . The effects of the type and number of FRP core/anchors on <SUB> τ u </SUB> of SFRP-coated geopolymer mortar were investigated. Furthermore, geopolymer mortar was reinforced with 0.5 and 1.5 wt% of short steel fibers to study the effects of fibers on <SUB> τ u </SUB> , and their results were compared with the efficiency of hybrid SFRP composites. The test results revealed that the hybrid SFRP composites had significant effects on the bond strength, and their bonding performance was relatively better than the fiber-reinforcement in geopolymer mortar. About 46% and 37% increments were observed in <SUB> τ u </SUB> through the use of hybrid SFRP composites and steel fiber-reinforcement, respectively. The effective bond length ( <SUB> L e </SUB> ) of hybrid SFRP composites was approximately 39 mm.</P>
Khalid, Muhammad Waqas,Kim, Young Il,Haq, Muhammad Aneeq,Lee, Dongju,Kim, Bum Sung,Lee, Bin Elsevier 2020 Ceramics international Vol.46 No.7
<P><B>Abstract</B></P> <P>Structural ceramics such as Al<SUB>2</SUB>O<SUB>3</SUB> and Al<SUB>2</SUB>O<SUB>3</SUB>–ZrO<SUB>2</SUB> composites are widely used in harsh environment applications. The conventional sintering process for fabrication of these ceramics is time-consuming method that requires large amount of energy. Microwave sintering is a novel way to resolve this problem. However, to date, very limited research has been carried out to study the effects of different ZrO<SUB>2</SUB> crystal structures on Al<SUB>2</SUB>O<SUB>3</SUB>–ZrO<SUB>2</SUB> composites, especially on the sintering kinetics, when fabricated by microwave sintering.</P> <P>The microwave hybrid sintering of Al<SUB>2</SUB>O<SUB>3</SUB> and Al<SUB>2</SUB>O<SUB>3</SUB>–ZrO<SUB>2</SUB> composites was performed in this study. Tetragonal zirconia and cubic zirconia were used as two different reinforcements for an α–alumina matrix, and the mechanical and thermal properties were studied. It was found that Al<SUB>2</SUB>O<SUB>3</SUB> experienced a remarkable increase in fracture toughness of up to 42% when t-ZrO<SUB>2</SUB> was added. Al<SUB>2</SUB>O<SUB>3</SUB>–c-ZrO<SUB>2</SUB> also showed increased fracture toughness. The sintering kinetics were also thoroughly investigated, and the average activation energy values for the intermediate stage of sintering were estimated to be 246 ± 11 kJ/mol for pure Al<SUB>2</SUB>O<SUB>3</SUB>, 319 ± 71 kJ/mol for Al<SUB>2</SUB>O<SUB>3</SUB>–c-ZrO<SUB>2</SUB>, and 342 ± 77 kJ/mol for Al<SUB>2</SUB>O<SUB>3</SUB>–t-ZrO<SUB>2</SUB>. These values indicated that the activation energy was increased by the addition of either type of ZrO<SUB>2</SUB>, with the highest value shown by Al<SUB>2</SUB>O<SUB>3</SUB>–t-ZrO<SUB>2</SUB>.</P>
Khalid, Azqa,Aslam, Muhammad,Qyyum, Muhammad Abdul,Faisal, Abrar,Khan, Asim Laeeq,Ahmed, Faisal,Lee, Moonyong,Kim, Jeonghwan,Jang, Nulee,Chang, In Seop,Bazmi, Aqeel Ahmed,Yasin, Muhammad Elsevier 2019 RENEWABLE & SUSTAINABLE ENERGY REVIEWS Vol.105 No.-
<P><B>Abstract</B></P> <P>Bioethanol has garnered a great interest as a potential energy source, mainly due to its sustainable and green nature. Generally, bioethanol is produced through the microbial conversion of biomass and biomass derived syngas. However, the dehydration and purification steps for achieving fuel-grade ethanol from the microbial production process consume tremendous amounts of energy. This high energy consumption limits the feasibility of microbial ethanol production on the commercial scale. In this context, selection of an optimal technology for product separation is essential for successful commercialization of microbially produced bioethanol. This article presents the recent developments in dehydration and purification technologies for bioethanol production using distillation and membrane based separation. Distillation and pervaporation are analyzed on the basis of the overall energy requirement, consumption, and economics. Pervaporation-assisted distillation approaches are also examined from the perspective of process systems engineering, including factors affecting the system performance. Furthermore, the role of simulation in technological development along with available mathematical models is discussed, and commercial status of pervaporation based separation is presented. Finally, the current status of the existing technology, challenges, and future research directions are identified from the perspective of achieving process sustainability on the industrial scale. Economic comparison between distillation and different hybrid schemes revealed that integrating distillation with membrane based separation techniques reduce the bioethanol production cost. Moreover, hybrid schemes that combine distillation with pervaporation, and steam stripping with vapor permeation are proved to be the best combinations for the cheapest bioethanol production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Recent developments in dehydration of bioethanol are presented. </LI> <LI> Conventional and membrane-based technologies are compared. </LI> <LI> Integrating pervaporation with distillation reduce the bioethanol production cost. </LI> <LI> The most economical hybrid schemes for bioethanol separation is identified. </LI> <LI> Operational optimization and thermodynamic evaluation of hybrid processes are required. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>