Damage Assessment Of Reinforced Concrete Beam With Various Depths By Using Acoustic Emission Technique

Penyelidikan ini adalah bertujuan untuk menggunakan Acoustic Emssion (AE) di dalam sistem pemantauan struktur kesihatan. Tiga kategori rasuk konkrit bertetulang dibina dengan perbezaan kedalaman rasuk dan setiap kategori mengandungi empat sampel dengan jumlah keseluruhannya 12 rasuk konkrit bertetulang. Semua sampel kajian diuji dengan mengenakan pembebanan lentur empat titik dan dikelaskan kepada pembebanan monotonik dan berperingkat. Di dalam kajian ini, setiap kategori rasuk konkrit bertetulang akan diuji dengan satu rasuk dikenakan bebanan monotonik dan selebihnya bebanan berperingkat. Berdasarkan pemantauan secara kasar, keseluruhan sampel ini mengalami mod kegagalan lentur, dan untuk mengumpul dan merekod kesemua isyarat AE data yang terlibat di dalam kajian ini, sensor jenis R6I dan sistem AE Digital MICRO-SAMOS (μSAMOS) digunakan bersama dengan perisian computer AEwin untuk menganalisis data. Selain itu, pengamatan secara visual juga dilaksanakan bagi membandingkan hasil analisis oleh AE. Objektif utama dalam kajian ini adalah untuk menyelidik dan mengkaji kebolehan AE dalam menentukan lokasi keretakan pada rasuk selain daripada mengkaji tenaga mutlak kumulatif untuk perilaku mekanikal yang berbeza bagi keretakan tersebut. Di samping itu, kaedah Intensity Analysis (IA) digunakan bagi menentukan tahap kerosakan dan kegagalan lentur pada rasuk berkenaan. Hasil penyelidikan ini mendapati bahawa teknik AE mampu menentukan dengan tepat lokasi keretakan mikro yang tidak dapat dilihat dengan mata kasar dan keretakan makro secara visual. Julat perbezaan adalah diantara 25mm dan 55mm. Berdasarkan kajian ini, didapati keretakan mikro akan terjadi apabila tenaga mutlak kumulatif melebihi 1.0 x 106 atto joule. Kesimpulanya penyelidikan ini mencapai objektif sebenar. ____________________________________________________________________________________________________________ This study aimed at using the Acoustic Emission (AE) in Structure Health Monitoring (SHM), since three categories of reinforced concrete (RC) beams (a total of 12 RC beams) with difference depth of beams. The study sample were tested in four-point bending setup under monotonic and stepwise loading, each category of RC beams contained four beams, one beam for monotonic loading and three beams for stepwise loading. All beams encountered flexural failure mode. In collecting the AE data, MICRO -SAMOS (μSAMOS) Digital AE system and R6I sensor were used, as AEwin software was used to analyze the data. Moreover, visual observation was conducted to compare with the AE results. The main interest of this research was to investigate the capability of AE in locating the concrete specimen’s cracks besides investigating the cumulative absolute energy for different mechanical behaviors of those cracks. On the other hand, Intensity Analysis (IA) method was used to quantified the damage level of the RC-beams associated with the crack flexural failure. The proposed method introduced that the differences of crack locations between visual observation and AE sources are between 25mm and 55mm. Also by comparing the visual observation to the AE result, when the cumulative absolute energy exceeds 1.0 x 106 attoJoule (aJ), the onset of the first crack occurs, and the recommended action at this stage is typically minor surface defects. Moreover, when the specimens affected by localization damage, the absolute energy increases dramatically for about five to seven times

Redefining Literacy: The Realities of Digital Literacy for Students with Disabilities in K-12

Technology has shaped the definition of literacy from the traditional meaning of having the ability to read and write to being a social practice that enables individuals to learn and interact with the world. With this notion of literacy, technology has become a tool to motivate and engage all learners through broad practices and platforms that could effectively strengthen a student’s learning experience. The shifting from printed content to digital form is a transfer point of the traditional understanding of literacy to a new and modern meaning. This has led to a new term known as digital literacy, whereby perceiving information, gaining knowledge, and expressing understanding for the purposes of learning are delivered through a digital format. Therefore, this study has comprehensively reviewed implementing technology into digital learning for K–12 students with disabilities. Moreover, the study has investigated special and general education teachers (n = 682) through open-ended questions to have a better understanding of the integration of learning and digital literacy. The results of the study have been interpreted to enhance the practice and research of the future of technology through digital literacy. Keywords: Digital literacy, students with disabilities, K-12, special education, general education, technolog

A Cervical Spine Gunshot Injury without Bone or Neurological Deficits

INTRODUCTION: Missile injuries of the spine has been reported literatures, The neurosurgical concern in such injuries is the degree of damage sustained during the bullet traversing the bony and neural tissue and their effect on long term follow up.PRESENTATIION: This report describes an interesting case of gunshot traversing the cervical vertebral body, the spinal cord and the posterior element without appearance of any bony destruction or neurological deficit.DISCUSSION: The patient was managed conservatively with long term follow up clinically and radiological with excellent recovery.CONCLUSION: Surgery should be served for specific cases according to the severity of the trauma and its effect

Process Characterization and Optimization of Roll-to-Roll Plasma Chemical Vapor Deposition for Graphene Growth

Large-scale production of graphene and other nanostructures remains a hindrance to their adoption in the semiconductor and materials manufacturing industries. The main purpose of this thesis is to develop an efficient and scalable technique for depositing graphene on various flexible substrates. Hence, a custom-built roll-to-roll capacitively coupled plasma chemical vapor system for deposition of graphene on flexible substrates is thoroughly described in this work. Graphene quality on Cu foil has been optimized for a roll-to-roll process using statistical optimization methods. Since graphene quality and uniformity depend on plasma input parameters, such as plasma power, gas pressure, and the gas mixture used, effects of input parameters have been explored to maximize graphene quality, as quantified by Raman spectroscopy using the ID/IG intensity ratio. Furthermore, in situ optical emission spectroscopy (OES) has been developed and utilized to determine the effects of several plasma species on graphene growth and quality. OES results demonstrate that graphene quality on Cu foil increases with CH radical emission; however, O and H atoms, C2 and CN radicals, and Ar+ ion all negatively correlate to graphene quality. Results aid in developing a conceptual model for a graphene growth mechanism that indicates the adverse impact of ion bombardment on graphene quality in the low-frequency capacitively coupled plasma. However, the existence of active carbon species in the plasma, such as CH radical, accelerates the growth process and leads to moderate-quality graphene deposition on Cu foil at web speeds reaching as high as 1 m/min. Nevertheless, graphene quality measured from Raman spectroscopy declines significantly with increased Cu foil velocity (web speed) in the roll-to-roll process, inducing a critical limitation in current production rates for roll-to-roll CVD nonmanufacturing techniques. With the aid of heat transfer modeling of the moving foil, we show that the graphene quality decrease is primarily due to Cu foil temperature decline with increased web speed. The Cu foil temperature distribution is determined both experimentally and numerically during roll-to-roll graphene growth as a function of web speed, plasma power and plasma length. The maximum Cu foil temperature in the plasma rises with increased plasma power due to increased heating from the plasma. However, the maximum Cu foil temperature decreases with increased web speed caused by higher heat advection by the moving foil. In addition, shortening the plasma slit (by decreasing the electrodes length) cools the Cu foil temperature and diminishes its temperature uniformity in the plasma region. Consequently, graphene crystallization, identified using Raman spectroscopy, improves with higher Cu foil temperatures. As a result, an optimum condition is defined by raising the plasma power, lowering the web speed and increasing the plasma region length, which consistently produces high-quality graphene on Cu foil. The throughput of graphene production can be increased by utilizing Ni foil as a substrate since carbon solubility in Ni is higher than in Cu. Thus, the effects of web speed and plasma power on Ni foil temperature distribution are evaluated during graphene deposition in the roll-to-roll process. Furthermore, the Ni foil cooling rate, which strongly affects carbon atom segregation from Ni after the growth process, is derived from the heat transfer model. Plasma power has negligible effects on the cooling rate, whereas the web speed has a significant impact on the cooling rate. Consequently, graphene has comparable quality at different plasma powers, whereas web speed controls graphene quality, particularly with regards to uniformity and thickness. Our work highlights the benefits of using Ni foil in a roll-to-roll process for graphene deposition at higher web speeds and lower substrate temperatures, rather than using Cu foil, which requires significantly more substrate heating. Plasma plays a crucial role in heating the foil for graphene deposition in the roll-to-roll process, without the need of a supplemental heating source. Thus, accurate measurement of the translational gas temperature in the plasma is vital, since gas temperature strongly influences the foil temperature distribution, which, in turn, affects graphene growth kinetics. Optical emission spectroscopy (OES) is used to measure the rotational temperatures of N2 + (B-X), CN (B-X) and H2 (d3Πu → a3Σg +), and to determine accurate translational gas temperatures. Power dissipation in the plasma is also measured to understand gas temperature variation for the experimental input conditions. Thus, the effects of plasma power, gas pressure and the addition of nitrogen (N2), oxygen (O2) and methane (CH4) gases on power dissipation and gas temperature in a hydrogen (H2) plasma are assessed. The rotational temperatures measured from the gas species have different values due to the non-equilibrium nature of the plasma. Of the gases measured, the rotational temperature of N2 + is most accurate in representing the translational gas temperature. These results improve the understanding and control of the thermochemical environment for carbon nanostructure growth in the plasma chemical vapor deposition processes. Graphene quality significantly depends on gas pressure since our plasma roll-to-roll system is sustained by a capacitively coupled plasma that operates in two modes, depending on the gas pressure and discharge gap. The modes are identified as alpha and gamma modes, and are sustained by volume ionization and secondary electron emission processes, respectively. Up to our knowledge, the presence of both modes at 80 kHz plasma frequency has not previously been reported. Thus, a detailed characterization of argon plasma is attempted to determine the underlying plasma physics of the low-frequency plasma. Due to strong ion bombardment on the electrodes, the gamma mode coexists with the alpha mode, resulting in a hybrid mode. The voltage square waveform is found to play an important role in sustaining this hybrid mode. The hybrid mode exists at low gas pressures of 5.5 and 9.5 mbar in the plasma set power ranges from 300 to 1100 W. However, the plasma at 13.8 mbar gas pressure transforms from hybrid to gamma mode when the plasma set power is beyond 750 W due to increased secondary electron emission processes. The emission spectra measured from optical emission spectroscopy reveal the presence of non-Ar species in the gamma mode, such as H, CH, and C2. These species are sputtered from the graphite electrodes by ion bombardment to produce secondary electrons that sustain the gamma discharge. Results show the possibility of sustaining the hybrid mode at a low plasma frequency using a tailored waveform. As a results of these plasma characterization tools, we report a continuous and rapid rollto- roll deposition of thin graphite film on Cu foil. The composition of the Ar/H2/CH4/N2/O2 plasma plays significant role in the successful direct growth of the thin graphite film on copper foil. Optical emission spectroscopy is used to characterize the plasma during graphite synthesis and show that the addition of N2 enhances the plasma reactivity, and O2 was found to increase the deposition rate of the graphite film. The film was characterized by Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The described large-scale graphite production can produce a graphite-Cugraphite structure or uniform thin graphite films for thermal management applications in electronics devices. Graphene growth optimization, substrate thermal analysis, and plasma characterizations are used to control graphene mass-production in a custom-built roll-to-roll plasma CVD system. These techniques are addressed to provide a route for nanomanufacturing of graphene and graphite on Cu and Ni foils. These methods aid in understanding the correlations between process conditions and graphene quality, as well as the interactions between the plasma and the substrate, to yield high-throughput production of high-quality graphene. The procedure outlined here can be applied to efficiently scale-up the production of other micro- and nanomaterials

The Impact of E-Service Quality on the Customer Satisfaction of Electronic and Small Appliances Online Shoppers in Saudi Arabia

The objective of this quantitative study, which utilized a non-experimental, correlational predictive design, was to evaluate the association between perceptions of e-service quality by Saudi Arabian adult residents and their overall satisfaction with the online retailer from which they buy their electronics and small appliances products. The study also sought to determine to what extent e-service quality factors, as a group and independently, predict the customer satisfaction of the participants of this study. The participants of this study were limited to adults (18 years of age or older), male and female, who live in any region of Saudi Arabia, and have at least completed one transaction over the internet to buy electronics and small electrical appliances products.This study utilized a non-probability convenience sampling method “in which [the] respondents are chosen based on convenience and availability” (Creswell & Creswell, 2018, p. 150). The actual sample was 658 complete responses, which were more than 277 responses required by G*Power analysis. The study adopted Vajrapna’s (2019) scale to measure independent variables (overall e-service quality and its components) and dependent variable (e-customer satisfaction). The e-service quality consisted of seven components that include 36 measured attributes. The e-customer satisfaction consisted of five measured perceptions. The participants in the survey were invited to participate via social media applications, and data were collected using the QualtricsXM survey platform. Simple and multiple regression tests were used to analyze data and reach conclusions. The finding of this study revealed the importance of information quality component in influencing e-customer satisfaction. E-tailers that manage to improve the information presented on their website to match customer preference would gain a competitive edge over those who do not. The research suggested that Saudi e-tailers should activate the role of omni-channel to create a barrier of entry over international rivals with no physical store

Utilization of By‐Product Materials in Ultra High‐Performance Fiber Reinforced Cementitious Composites

This chapter presents a review on the use of various industrial wastes, by-products in the development of green ultra-high performance fiber-reinforced cementitious composites (UHPFRCCs), and their effects on mechanical properties of UHPFRCC, such as metakaolin, rejected fly ash, glass powder, and palm oil fuel ash. The outcomes of this chapter would encourage the use of by-product as a supplementary cementitious material. This could be useful in protecting the environment by minimizing the volume of waste disposed on the wasteland and minimizing the emission of greenhouse gases that are released during cement production, besides contributing to cost–saving, which could somehow contribute toward the sustainability of the concrete industry

An analysis of grammatical and associated errors found in the writing of third grade Saudi male students in four high schools in the city of Riyadh

The main aim of the thesis is to identify and analyse the types and frequency of grammatical, lexical and general linguistic errors made in the Arabic composition writings of the third year high school students in the city of Riyadh, Saudi Arabia. This study is to provide information that can be utilised in the improvement of teaching of the grammatical rules of the Arabic language to public school students. The approach is descriptive, analytical and classificatory.Chapter one deals with the research problem, aims and significance of the study, and also discusses the limitations of the study.Chapter two reviews the background to Arabic grammar in the Saudi educational system in the country, particularly in the secondary school system.Chapter three is an extensive literature review on the background of grammatical errors and Arabic grammatical rules.Chapter four examines the prevalence of grammatical errors, their causes and complaints.Chapter five reviews the efforts and attempts to simplify Arabic grammatical rules as a reaction to the dilemma of Arabic grammar and the prevalence of the grammatical errors.Chapter six deals with the research design and methodology of the study undertaken.Chapter seven presents and analysis the main results of this study. It starts with frequency of the grammatical errors and the percentage of the students who committed grammatical errors. This chapter also presents the frequency of types of errors for each grammatical component and finally it highlights the general linguistic errors found in the students' writings.Chapter eight, which is the final chapter, is devoted to a conclusion and implications for practice and future research

Investigating xanthine oxidase toxicity models in cultured cerebellar granule neurons

In the last few decades, evidence has been accumulating for a role for xanthine oxidoreductase (XOR)-generated toxic reactive oxygen species (ROS) in a variety of pathological conditions that affect different organ systems. This enzyme in mammals exists in two inter-convertible forms: xanthine dehydrogenase (XDH) (the predominant intracellular form under physiological conditions) and xanthine oxidase (XO). A combination of XO and its oxidizable substrate xanthine (X) (or hypoxanthine (HX)) is widely used as a model to produce ROS and to study their effects in a variety of cell culture studies. However, the effect of the combination of XOR and the reduced nicotinamide adenine dinucleotide (NADH) in cell cultures is much less studied. NADH is another oxidizable substrate for XOR that binds to a different site on the enzyme from that of X binding. The aim of this project was to investigate some aspects of the in vitro toxicity of XOR, which might provide more insights into its in vivo toxicity. The main investigation was a comparison between the well studied X / XO and the much less studied NADH / XO toxicity models. Also, secondary studies were undertaken to investigate those aspects of X / XO toxicity where there are uncertainties about them. These studies were performed using primary cell cultures. Cell cultures are now widely used to study different diseases, and although they have their drawbacks, they have their advantages over the in vivo studies. For this project, primary cultures of cerebellar granule neurons (CGNs) were used. In the beginning, some problems were encountered with CGNs. The main problem was the immediate damage induced to the neurons (including those in the control groups) at the intervention/experiments day (i.e. day 8 or 9 after plating) by manipulating the cultures (i.e. aspirating the culture medium, adding treatment and control vehicles, and adding the restoration medium). After several months of investigation, it was serendipitously discovered that the immediate damage seen in the neurons (including those in the control groups) when they are manipulated at the experiments/intervention day was due to glutamate excitotoxicity (through activating its N-methyl-D-aspartate (NMDA) receptors). The source of glutamate was the fresh serum which is present at 10% V/V in the fresh culture medium that is added to the cultures at that day. After solving this problem, it was possible to conduct reliable experiments to investigate XO toxicity models. Regarding investigating XO toxicity, it was found that both of the X / XO and NADH / XO combinations were toxic to cultures of CGNs. However, the concentration of NADH needed to cause the toxicity was much higher than that of the other substrate, X, which is in agreement with previous cell-free experiments that showed that NADH is a much weaker substrate than X for the bovine milk XO used here. Blocking the site of X binding on XO prevented X / XO toxicity, but did not prevent NADH / XO toxicity. On the other hand, blocking the site of NADH binding prevented both X / XO and NADH /XO toxicities. Another difference between the two systems was that deactivating either superoxide or hydrogen peroxide (both are ROS) generated by XO prevented NADH / XO toxicity, whereas although deactivating hydrogen peroxide prevented X / XO toxicity, deactivating superoxide generated from this combination did not. In the NADH / XO system, an extracellular metal contaminant (likely contaminating XO powder/preparation) seemed to be involved in the toxicity. The two toxicity models were similar in the mediation of toxicity by intracellular iron ion. In X / XO toxicity, although superoxide generated extracellularly from the combination has no role in the toxicity, intracellularly produced superoxide seemed to play a role. Conclusions: 1. Culturing/experimental conditions have been optimised for viability studies in CGNs cultures. 2. The combination of NADH and XO induces damage to CGNs, where although blocking the NADH binding site prevents this damage, blocking the X binding site does not. It is feasible that the oxidation of NADH by some forms of XOR (other than the one used here) that are known to be very efficient in oxidizing NADH might produce in vivo toxicity. 3. A possibility raised by this study is that a metal (like the metal contaminant proposed to play a role in NADH / XO toxicity in this study) might contribute to XOR toxicity in vivo. 4. Intracellular superoxide often mediates XOR toxicity. 5. The results add support to many previous studies which suggested that intracellular hydroxyl radical (or a similar species) is involved in XOR toxicity