666 research outputs found
New Key Exchange Protocol Based on Mandelbrot and Julia Fractal Sets.
No full textIn this paper, we propose a new cryptographic key exchange
protocol based on Mandelbrot and Julia Fractal sets. The Fractal based key exchange protocol is possible because of the intrinsic connection between the Mandelbrot and Julia Fractal sets. In the proposed protocol, Mandelbrot Fractal function takes the chosen private key as the input parameter and generates the corresponding public key
Assessing the impact of non-pharmaceutical interventions on SARS-CoV-2 transmission in Switzerland
No full textFollowing the rapid dissemination of COVID-19 cases in Switzerland, large-scale non-pharmaceutical interventions (NPIs) were implemented by the cantons and the federal government between 28 February and 20 March 2020. Estimates of the impact of these interventions on SARSCoV-2 transmission are critical for decision making in this and future outbreaks. We here aim to assess the impact of these NPIs on disease transmission by estimating changes in the basic reproduction number (R0) at national and cantonal levels in relation to the timing of these NPIs. We estimated the time-varying R0nationally and in eleven cantons by fitting a stochastic transmission model explicitly simulating within-hospital dynamics. We used individual-level data from more than 1000 hospitalised patients in Switzerland and public daily reports of hospitalisations and deaths. We estimated the national R0to be 2.8 (95% confidence interval 2.1-3.8) at the beginning of the epidemic. Starting from around 7 March, we found a strong reduction in time-varying R0with a 86% median decrease (95% quantile range [QR] 79-90%) to a value of 0.40 (95% QR 0.3-0.58) in the period of 29 March to 5 April. At the cantonal level, R0decreased over the course of the epidemic between 53% and 92%. Reductions in time-varying R0were synchronous with changes in mobility patterns as estimated through smartphone activity, which started before the official implementation of NPIs. We inferred that most of the reduction of transmission is attributable to behavioural changes as opposed to natural immunity, the latter accounting for only about 4% of the total reduction in effective transmission. As Switzerland considers relaxing some of the restrictions of social mixing, current estimates of time-varying R0well below one are promising. However, as of 24 April 2020, at least 96% (95% QR 95.7-96.4%) of the Swiss population remains susceptible to SARS-CoV-2. These results warrant a cautious relaxation of social distance practices and close monitoring of changes in both the basic and effective reproduction numbers
Mechanical, thermal, and morphological properties of graphene reinforced polycarbonate/acrylonitrile butadiene styrene nanocomposites
No full textNanocomposites of polycarbonate/acrylonitrile butadiene styrene (PC/ABS) with (70/30) composition containing different amounts of graphene nanoplates (GNPs) (1, 3, and 5 wt%) were prepared by melt‐blending in a twin‐screw extruder. The structural, morphological, mechanical, and thermal properties of the nanocomposites were investigated. The Young's modulus and flexural modulus of the nanocomposites were increased by 30 and 54%, respectively, when 3 wt% GNPs was added. The flexural strength and tensile strength of the PC/ABS/GNPs nanocomposites increased up to a loading of 3 wt% GNPs. The incorporation of GNPs enhanced the thermal stability and char yield of the nanocomposites. X‐ray diffraction and field emission scanning electron microscopy showed uniform dispersion and alignment of GNPs in PC/ABS matrix. The interaction between the GNPs and the PC/ABS matrix were confirmed by Fourier transform infrared spectra. Therefore, the PC/ABS/GNP nanocomposites with improved flexural and tensile properties, without loss of extensibility and good thermal properties may have promising applications in automotive, electric tools, household, communication, and safety appliances. POLYM. COMPOS., 37:1633–1640, 2016
A geometric characterization of c-optimal designs for heteroscedastic regression
No full textWe consider the common nonlinear regression model where the variance as well as the mean is a parametric function of the explanatory variables. The c-optimal design problem is investigated in the case when the parameters of both the mean and the variance function are of interest. A geometric characterization of c-optimal designs in this context is presented, which generalizes the classical result of Elfving (1952) for c-optimal designs. As in Elfving's famous characterization c-optimal designs can be described as representations of boundary points of a convex set. However, in the case where there appear parameters of interest in the variance, the structure of the Elfving set is different. Roughly speaking the Elfving set corresponding to a heteroscedastic regression model is the convex hull of a set of ellipsoids induced by the underlying model and indexed by the design space. The c-optimal designs are characterized as representations of the points where the line in direction of the vector c intersects the boundary of the new Elfving set. The theory is illustrated in several examples including pharmacokinetic models with random effects. --c-optimal design,heteroscedastic regression,Elfving's theorem,pharmacokinetic models,random effects,locally optimal design,geometric characterization
Seawater desalination using spiral wound kenaf membrane / Azman Ismail
No full textMembrane technology is widely used in many industries, such as water treatment and water reclamation plant. The problems with current membrane technology are low flux with low rejection and high fouling. Hence, many researchers develop membranes with different materials to improve membrane performance. The performance of the membrane is depending on material used during membrane fabrication. However, there are still lack of research focusing on using biomaterials. Therefore, this research proposing a new material extracted from Kenaf plant. The material chosen in this study was Polysulfone (PSF), Polyvinylpyrrolidone (PVP), Microcrystalline Cellulose (MCC), and N-Methyl 2 Pyrrolidinone (NMP). The objectives are to study the effect of Kenaf Microcrystalline Cellulose (MCC) on membrane morphology and membrane performance in terms of water flux and salt rejection. Secondly is to evaluate the performance of the Thin-film Composite of Kenaf Microcrystalline Cellulose membrane. Thirdly is to develop spiral wound Kenaf MCC membrane for desalination and the fourth objective is to evaluate the performance of Kenaf Desalination system in term of water flux and salt rejection. The membranes were fabricated by using a dry-wet phase inversion method using a glass rod and glass plate. The membranes were analysed by using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) to understand the morphology and surface pore size. Three of the membrane samples were then undergone surface treatment using Thin-film Composite (TFC) and tested again using 2000ppm and 35000ppm Sodium Chloride (NaCl) concentration. SEM images show that the membrane exhibits a finger-like structure inside the membrane sublayer. MWCO study shows that all the membranes are in the range of ultrafiltration. Wettability study shows that Kenaf MCC has the highest hydrophilic characteristic, which is 60° contact angle. The highest NaCl rejection was by TFC MK3, which is 98.9% rejection using 1.5 MPa pressure. MCC Kenaf membrane (MK3) shows a good pure water flux value, which is 2.864 L/m²h at 0.5h. Moreover, it was found that increasing Kenaf MCC concentration in dope solution will reduce the rejection because of the MCC characteristics to create bigger pore size. The highest NaCl rejection and water flux is from Spiral-wound Kenaf MCC, which is 66% and 181 L/m2h. These results indicate that the Kenaf Desalination System membrane can be used to remove NaCl in seawater
The impact of educational change in Malaysian Smart Schools on Islamic Education teachers and students
No full textThis study is an attempt to investigate the impact of educational change in Malaysian Smart Schools on Islamic Education teachers and students. This study is trying to understand all aspects of the change process in Smart Schools and to understand the problems of students and teachers as they endeavour to improve learning and teaching in Smart Schools. Following the implementation of the Smart School pilot projects in the Malaysian secondary schools. this study is aimed at suggesting an approach that can be used to incorporate the use of computers and ICT in Islamic Education by taking into consideration the views. experiences, expectations and needs of the teachers and the students themselves. In examining the new initiative of Smart Schools, a mixed methods design was adopted to gather the data needed from Islamic Education teachers and students.
A grounded theory approach was used in the early phase of the study as this approach is suitable for this relatively new field where little research has been done. This research began with an exploratory phase which involved the use of focus groups as a means to gain knowledge of respondents' views, perceptions and attitudes about Smart Schools. The results from the focus group were used as initial data to develop a structured questionnaire for a large survey study in the Smart Schools. The last phase of research involved an in-depth interviewing process to clarify and validate the previous two phases of research.
This study found that the use of computers was the core feature of the change phenomenon in Smart Schools. Islamic Education teachers and students were hardly coping with the task of incorporating the use of new technology in their teaching and learning. Many barriers and obstacles in using new technology were reported by Islamic Education teachers and students. The most important barriers identified in this study are the lack of computers and available resources, lack of training, shortage of time and the pressure of a heavy syllabus and examination centred learning. This study also notes the influence of subject culture in determining the use of computer in Islamic Education. This study also suggests some recommendations for the future implementation of Smart Schools throughout Malaysia by year 2010
Patterns of implicit and non-follower retweet propagation: investigating the role of applications and hashtags
No full textExisting literature on retweets seems to focus mainly on retweets created using explicit, formal retweeting mechanisms, such as Twitter's own native retweet function, and the prefixing of the terms 'RT' or 'via' in front of copied tweets. However, retweets can also be made using implicit, informal mechanisms. These include tweet replies and other mechanisms, which use neither the native nor RT/via mechanisms, but their content and timelines suggest the likelihood of being a retweet. Moreover, retweets can also occur with or without a defined follower/following network path between a tweet originator and a retweeter. This paper presents an initial taxonomy of propagation based on seven different ways a tweet may spread: native, native non-follower, RT/Via, RT/Via non-follower, replies, non-follower replies and other implicit 'retweets'. An experiment has examined this new model, by investigating where tweets containing URLs from the domains of online petitions, charity fundraisers, news portals, and YouTube videos can be classified into the seven different categories. When including other implicit 'retweets', more than 50% of all the retweets found across all four domains were classified as implicit retweets, while more than 79% of all retweets were made by non-followers. More work needs to be done on the composition of other implicit 'retweets'. Initial investigations found hashtags in 99-100% of these tweets, suggesting that retweeting using conventional mechanisms may not be the main method that URLs get propagated across microblogs
Dark retweets: investigating non-conventional retweeting patterns
No full textRetweets are an important mechanism for recognising propagation of information on the Twitter social media platform. However, many retweets do not use the official retweet mechanism, or even community established conventions, and these "dark retweets" are not accounted for in many existing analysis. In this paper, a comprehensive matrix of tweet propagation is presented to show the different nuances of retweeting, based on seven characteristics: whether it is proprietary, the mechanism used, whether it is directed to followers or non-followers, whether it mentions other users, if it is explicitly propagating another tweet, if it links to an original tweet, and what is the audience it is pushed to. Based on this matrix and two assumptions of retweetability, the degrees of a retweet's "darkness" can be determined. This matrix was evaluated over 2.3 million tweets and it was found that dark retweets amounted to 12.86% (for search results less than 1500 tweets per URL) and 24.7% (for search results including more than 1500 tweets per URL) respectively. By extrapolating these results with those found in existing studies, potentially thousands of retweets may be hidden from existing studies on retweets
BRINGING READING RESEARCH IN MULTILINGUAL NUSANTARA INTO A NEW DIRECTION THROUGH EYE-TRACKING
No full textCurrent understanding of the psychological mechanisms underlying reading comprehension among multilinguals are typically limited to external observations of their ability to read and comprehend text. Additionally, descriptions of the nature of comprehension processes relied perilously on the use of memory taken after the reading process. In this article we introduce the potential of using eye tracking as a tool in collecting internal attention data for a deeper understanding of EFL text processing among multilinguals. The eye tracking procedures will enable researchers to combine perspectives collected from internal and external observations, to explicate and elucidate the complex cognitive processes of the multilingual when involved in reading. Since the use of the eye-tracking in reading research methodology is fairly new, particularly in multilingual contexts such as Malaysia and Nusantara in general, we will emphasize how progress has been achieved elsewhere in understanding text processing through the use of eye-tracking. The article will introduce relevant research projects that can be conducted using eye-tracking, after sketching the historical progression of eye-tracking research in the field. It concludes by suggesting that eye-tracking can provide a framework for studying the full range of the multilingual readers’ competencies in reading while expanding related theories about EFL reading.Keywords: External attention, eye-tracking, internal attention, oculomotor-behaviours, oral-comprehension and multilingual readersCite as: Mihat, W., Azman, H. & Soh, O.K. (2018). Bringing reading research in multilingual Nusantara into a new direction through eye-tracking. Journal of Nusantara Studies, 3(2), 107-123. http://dx.doi.org/10.24200/jonus.vol3iss2pp107-12
Development of dye-sensitized solar cells with natural dye doped on metal oxide / Ahmad Mazli Azman
No full textThe combination of post covid recovery, depleted fossil fuel reverse and extreme weather condition led to surge in demand for energy. Solar energy is a sustainable industry that capture interest energy industry in the world. The material that most commonly used nowadays is from synthetic dye. Therefore, natural dye from plan is proposed. This is because the natural never pollute like synthetic dye as they are obtained. The objective of this study is to find out the best extraction time of natural dye in metal oxide. The natural dye was extracted from Pandanus Amaryllifolius (leaves) using convectional extraction method and doped into metal oxide which is Magnesium Oxide (MgO) for 5 - 7 days. The result obtained had showed the concentration of dye increasing as the time extract is increase. The natural dye is also tested with conductivity and the result showed a decreasing trend. Also, by FTIR, the longer the magnesium oxide is doped into the sample, the higher the transmittance showing the presence of O-H bonding determine the ability for the adsorption of solar energy. To conclude, natural dye from Pandan leaves has the potential to be used for the Dye-Synthesized Solar Cells (DSSC)
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