19672 research outputs found
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Kinetic and thermodynamic analysis of iron oxide reduction by graphite for CO 2 mitigation in chemical‐looping combustion
No full textChemical-looping combustion (CLC) provides a platform to generate energy streams while mitigating CO2 using iron oxide as a carrier of oxygen. Through the reduction process, iron oxide experiences phase transformation to ultimately produce metallic iron. To understand iron oxide reduction characteristics and optimally design the fuel reactor, kinetic and thermodynamic analyses were proposed, utilizing graphite. This study aims to evaluate the reduction behavior under the non-isothermal process of various mixture ratios of hematite and graphite via thermogravimetric analysis with simultaneously evaluating evolved gases using a Fourier transform infrared spectrometer. The Coats-Redfern model was employed to approximate the kinetic and thermodynamic parameters which assessed the different reaction mechanisms together with the distributed activation energy model (DAEM). The results revealed that the hematite-to-graphite ratio of 4:1 had the highest reduction degree and had three distinct peaks representing three iron oxide reduction phases. The zero-order reaction mechanism agreed with the experimental results compared with other reaction models. The thermodynamic analysis showed an overall endothermic spontaneous reaction for the three phases which signified the direct reduction of the iron oxides. The DAEM result validated a stepwise reduction of iron oxides to metallic iron. The study aids the optimal design of the CLC fuel reactor for enhanced system performance. © 2020 John Wiley & Sons Lt
EMBLR: A High-Performance Optimal Routing Approach for D2D Communications in Large-scale IoT 5G Network
No full textCoping with the skyrocketing needs for massive amounts of data for the future Fifth Generation (5G) network, Device-to-Device (D2D) communications technology will provide seamless connectivity, high data rates, extended network coverage, and spectral efficiency. The D2D communications are a prevalent emerging technology to achieve the vision of symmetry in the Internet of Things (IoT) services. However, energy resource constraints, network stability, traffic congestion, and link failure of the devices are the crucial impediments to establish an optimal route in the D2D communications based IoT 5G network. These obstacles induced packet drop, rapid energy depletion, higher end-to-end delay, and unfairness across the network, leading to significant route and network performance degradation. Therefore, in this paper, an energy, mobility, queue length, and link quality-aware routing (EMBLR) approach is proposed to overcome the challenges and boost network performance. Moreover, a multicriteria decision making (MCDM) technique is utilized for the selection of the intermediate device in an optimal route. Extensive simulation has been conducted and proven that the proposed routing approach significantly enhances network performance. Overall, results have been carried out in Quality of Service (QoS) performance metrics and compared with other well-known routing approaches. © 2020 by the authors. Licensee MDPI, Basel, Switzerland
Partial characterization and in vitro evaluation of a lytic bacteriophage for biocontrol of Campylobacter jejuni in mutton and chicken meat
No full textCampylobacter jejuni is a major foodborne pathogen causing acute bacterial enteritis worldwide. Screening of novel bacteriophages as biocontrol tools to eliminate C. jejuni in food during pre- and postharvest is an emerging research field. In this study, we partially characterized C. jejuni bacteriophage CJ01 for potential use as biocontrol agent. Transmission electron microscopy revealed bacteriophage CJ01 belonged to the Myoviridae family with a genome size of approximately 136 kb. The results of host range assay revealed CJ01 was able to infect C. jejuni and C. lari strains, with burst size about 35 phages per infected cell and latent period of 30 min. The effectiveness of bacteriophage CJ01 (with 100 multiplicity of infection = 100) was determined in mutton and chicken meat artificially contaminated with C. jejuni. The amount of C. jejuni in treated mutton and chicken meat were significantly reduced by 1.70 log CFU/g and 1.68 log CFU/g, respectively, after 48 hr stored at refrigeration temperature (4°C). The data presented here suggest that bacteriophage CJ01 can be used as a postharvest biocontrol agent. © 2020 Wiley Periodicals, Inc
On the speculative nature of cryptocurrencies: A study on Garman and Klass volatility measure
No full textWe propose to measure volatilities of 102 active cryptocurrencies using Garman and Klass (GK) volatility measures and model the measures using asymmetric bilinear Conditional Autoregressive Range (ABL-CARR) model. Results reveal volatility persistence and leverage effects which can improve the predictability of volatility, reduce risk and hence lessen the level of speculation in cryptocurrency market. We further relate volatility features for the top five cryptocurrencies to their time of development and transaction speed and recommend investors to distinguish between long-term or short-term speculation in their investment profile. © 2018 Elsevier Inc
Surface analysis of early retrieved polyethylene tibial inserts for both knees in total knee replacement
No full textThis study involves the failure analysis of a pair of ultra-high-molecular-weight-polyethylene (UHMWPE) knee tibial inserts from Scorpio® fixed-bearing total knee system by Stryker, which were retrieved from Total Knee Replacements (TKR) that was performed on 64 years old male patient with periprosthetic joint infection detected on both knees. Although the implants were removed due to infection, surface analysis was essential to be studied in order to analyse the surface damage mode of short-term implants. This study reports relevant damage mechanisms seen in early-retrieved UHMWPE tibial inserts (implanted for 6 and 8 months) and further analysis of chemical, physical and mechanical properties that possibly accompanied with failure. The surface characterization was done using a 3D laser microscope and Scanning Electron Microscope (SEM) to evaluate surface damage and dimensional change of both UHMWPE tibial inserts. Nano-indentation is used to measure the hardness and elasticity modulus of the tibial inserts. Attenuated Total Reflection-Fourier Transform Infra-Red (ATR-FTIR), Differential Scanning Calorimetry (DSC) and Gel Permeation Chromatography (GPC) were used to characterize the chemical and physical properties of the inserts. In present study, retrieved polyethylene inserts with short implantation duration was considered to have high-grade wear modes. The high incidence of micro pits (with the average depth of 27.5 μm for 6 months insert and 18 μm for 8 months insert) and scratches as the observed surface defects strengthen the role played by the particles upon defects generation for both tibial inserts. The average surface roughness of 6 and 8 months inserts were 1.6798 μm and 1.2376 μm, respectively. The rough surface (4.207 μm) of region 4 at the lateral compartment proves that the 6 months tibial insert suffered more damage due to loosening defect where the radiolucencies (the gap between bone and cement) were seen below medial and lateral aspects of the tibial tray. Our data demonstrated a strong association between the change of molecular weight and degradation of mechanical properties with wear for both inserts. The oxidation induced wear mechanism was observed on 6 months old insert due to the presence of delamination features with the evidence of in vivo oxidation from IR analysis. © 2019 Elsevier Lt
A question answering system in hadith using linguistic knowledge
No full textQuestion answering system aims at retrieving precise information from a large collection of documents. This work presents a question answering method to apply on Hadith in order to provide an informative answer corresponding to the user's query. Hadith englobes stories and qualification of the prophet Muhammad (PBSL). It also includes the sayings of his companions and their disciples. The problem with current methods is that they fail to capture the meaning when comparing a sentence and a user's query; hence there is often a conflict between the extracted sentences and user's requirements. However, our proposed method has successfully tackled this problem through: (1) avoiding extract a passage whose similarity with the query is high but whose meaning is different. (2) Computing the semantic and syntactic similarity of the sentence-to-sentence and sentence-to-query. (3) Expanding the words in both the query and sentences to tackle the fundamental problem of term mismatch between sentences and the user's query. Furthermore, in order to reduce redundant Hadith texts, the proposed method uses the greedy algorithm to impose diversity penalty on the sentences. The experimental results display that the proposed method is able to improve performance compared with the existing methods on Hadith datasets. © 2019 Elsevier Lt
Two-stage multi-modal system for low frequency and wide bandwidth vibration energy harvesting
No full textWind power has gained interest of research over past decades as renewable energy solution. Vibration controller is usually installed to mitigate vibration while part of structural vibration is potential to be harvested as regenerative energy source using vibration energy harvester and supplied to vibration controller to create a self-powered system. This study aims to develop a novel two-stage multimodal piezoelectric cantilever energy harvester system design to harness vibration of low-frequency range (<10 Hz). The primary system consists of a height-adjustable fixture, two metallic cantilever beams with different tip mass to achieve low natural frequency whereas the secondary system consists of a cantilever piezoelectric bimorph plate. Prototype of the proposed design is fabricated, and the experimental results indicate that setting the gap at 1 cm between primary and secondary systems improves voltage generation by 82.83%–349.87%. The operational bandwidth of two-stage multimodal system is also extended to the range of 5.5 Hz–7.0 Hz. © 2019 Elsevier Lt
Two decades of research on early career faculties (ECFs): A bibliometric analysis of trends across regions
No full textEarly Career Faculties (ECFs) are an important demographic of university faculty population shaping the future of the institution and higher education, despite the challenges they face as new academics. Analysis of scholarly output on ECFs offers useful data to inform and aid both national policy formulations and institutional planning decisions especially in ECFs' support and development. Peer-reviewed high impact journals and academic databases provide highly valid and reliable sources of data and information on ECFs. This study examines the trend of ECFs research over two decades comparing scholarly output and research impact across global regions, in Web of Science and Scopus Elsevier. The bibliometric analysis highlights key topics of research and publications related to ECFs and identify the regions and countries most actively research on the topic. The trend of research on ECFs has been found to increase exponentially beginning the 1990s worldwide, mostly from western institutions (76%). Publications after the year 2012 focused more on issues related to ECFs' preparation towards life in academia, their motivation, and challenges, the support structure for ECFs and strategies to adapt to life as faculty members. Such bibliometric analysis findings can be a useful reference for policy formulation within national or regional systems of higher education, and institutional strategic planning. © 2020 Universiti Putra Malaysia Press
A study on modified accelerated diagnostic protocol to safely discharge low-risk chest pain patients in emergency department
No full textBackground: Evaluation of chest pain patients in emergency departments to distinguish between high-risk patients who require admission and low-risk patients who can be managed as outpatients is a challenging task. Objective: The aim of this study was to evaluate the efficacy of Observation Ward Short Stay Evaluation Service for Chest Pain Protocol to identify and safely discharge low-risk patients with low incidence of major adverse cardiac events within 30 days. Methods: This was a single center prospective observational study, conducted from 1 March 2016 to 31 August 2016 at the Emergency and Trauma Department, Hospital Kuala Lumpur, Kuala Lumpur. Observation Ward Short Stay Evaluation Service for Chest Pain Protocol was used to evaluate patients presented with chest pain or angina equivalents. The components involved Thrombolysis in Myocardial Infarction (TIMI) score, serial electrocardiograms, high-sensitivity cardiac troponin T, and exercise treadmill test. Low-risk patients were patients with TIMI < 2, normal serial electrocardiogram, high-sensitivity cardiac troponin T ≤ 14 ng/L, and negative exercise treadmill test. If anyone of the components was not fulfilled patients were considered as high risk, and they were either admitted or referred to clinic for further intervention. Low-risk patients were allowed for discharged. All patients were followed-up in 30 days for any incidence of major adverse cardiac events. Results: Totally, 174 patients were studied. Observation Ward Short Stay Evaluation Service for Chest Pain Protocol managed to discharge 102 (58.6%) patients, and 84 (82.4%) of them underwent exercise treadmill test. About 46 (54.8%) patients had negative exercise treadmill test, whereas 38 (45.2%) patients had either positive or inconclusive exercise treadmill test, and they were referred to physician clinic for further cardiac assessment. None of the patients with negative exercise treadmill test developed major adverse cardiac events in 30 days. The sensitivity and the negative predictive value (NPV) of Observation Ward Short Stay Evaluation Service for Chest Pain Protocol were both 100%. Conclusion: Observation Ward Short Stay Evaluation Service for Chest Pain Protocol can be applied in emergency departments to identify and safely discharge patients with low risk of major adverse cardiac events in 30 days. © The Author(s) 2019
A behavioral intention model for SaaS-based collaboration services in higher education
No full textDespite numerous potential benefits of cloud computing usage, there are still some users reluctant to adopt this technology. This study aims to investigate the factors that influence student adoption of cloud computing in higher education settings and to generate a set of decision rules to guide through a series of critical decisions needed in this adoption process. Accordingly, a two-stage Structural Equation Modelling (SEM)-Classification and Regression Trees (CART) methodology is applied in order to test the overall research model and related hypotheses as well as to generate decision rules to predict behavioural intention towards adoption. Using survey questionnaire method, a total of 418 valid questionnaires are collected from students of top-ranked Malaysian universities. The results show that task-technology fit, performance expectancy, effort expectancy, social influence, self-efficacy, collaboration technology experience, peer and superior influence and familiarity with group members are significant predictors of intention to adopt cloud computing. The findings of this study can serve as a guideline for the ministry of education, university administrators, and cloud service providers to manage the successful adoption of cloud computing in the education sector. © 2019, Springer Science+Business Media, LLC, part of Springer Nature