Relationship between creep time dependent index and Paris Law parameters for bituminous mixtures

Published ArticleBituminous mixtures undergo cracking, either top-down or bottom-up, as a consequence of the repeated application of traffic loads, thermal cycling or a combination of the two mechanisms. Cracking is considered as one of the major distress modes in asphalt pavements. This study presents a method to characterise crack resistance of asphaltic mixtures containing waste materials using a semi-circular bending (SCB) fracture test. Three different bituminous mixtures containing incinerator bottom ash waste and one control mix, containing limestone, were tested under cycling SCB loading conditions at 5°C and the results were interpreted using Paris Law. The same mixtures were also tested under controlled stress creep conditions at the same temperature. This paper examines the link between the time dependent index from creep tests with the n parameter from the Paris Law model, based on visco-elastic continuum damage mechanics analysis and linear elastic fracture mechanics principles

Performance enhancement of large scale networks with heterogeneous traffic.

Finally, these findings are applied towards improving the performance of the Differentiated Services architecture by developing a new Refined Assured Forwarding framework where heterogeneous traffic flows share the same aggregate class. The new framework requires minimal modification to the existing Diffserv routers. The efficiency of the new architecture in enhancing the performance of Diffserv is demonstrated by simulation results under different traffic scenarios.This dissertation builds on the notion that segregating traffic with disparate characteristics into separate channels generally results in a better performance. Through a quantitative analysis, it precisely defines the number of classes and the allocation of traffic into these classes that will lead to optimal performance from a latency standpoint. Additionally, it weakens the most generally used assumption of exponential or geometric distribution of traffic service time in the integration versus segregation studies to date by including self-similarity in network traffic.The dissertation also develops a pricing model based on resource usage in a system with segregated channels. Based on analytical results, this dissertation proposes a scheme whereby a service provider can develop compensatory and fair prices for customers with varying QoS requirements under a wide variety of ambient traffic scenarios.This dissertation provides novel techniques for improving the Quality of Service by enhancing the performance of queue management in large scale packet switched networks with a high volume of traffic. Networks combine traffic from multiple sources which have disparate characteristics. Multiplexing such heterogeneous traffic usually results in adverse effects on the overall performance of the network

Cultural & Responsible Tourism

Fidaa Alfalata's & Mostafa Hassan's poster on cultural tourism

Student performance on computer-based tests versus paper-based tests in introductory financial accounting: UAE evidence

© 2018, Allied Academies. This study examines whether the use of technology-based assessment tool affects the examinations\u27 scores of students from both genders. The study, therefore, ascertains whether the mode of student testing (computer-based or paper-based) in an introductory-level financial accounting course impacted students\u27 scores (a direct measure of learning). In doing so, the study relies on experimental design wherein the type of examination is being controlled together with other contextual variables such as timing of the exam, instructors, and the gender of students. The sample consists of 78 students undertaking financial accounting courses at Zayed University during the summer semester. A simple difference in means statistics test shows that there is no statistically significant difference between the students\u27 paper-based and computerbased scores. However, benchmark regression analysis showed that males performed better than females on CBT, and females outperformed males on PBT. The paper provides evidence from the Gulf region as of how technology-based assessment is affected by the gender, which matter needs to be addressed by university instructors working in Middle East universities

The Role of Writing Center Tutorials of ESL Students: Exploring Tutors, Tutees, and Instructors’ Perceptions

The purpose of this study was to investigate the role of the writing center tutorials. Based on the assumptions of the constructivist theory, this research tried to present a cognitive framework for better tutoring at the writing center and suggested better accommodations for ESL tutees. this exploratory study investigated the role of the writing center tutorials offered to ESL students through the perceptions of tutors, ESL tutees, and university instructors. Methods. Eighty nine international /ESL students and 23 tutors were selected. They were given a survey to respond to. Afterwards ten out of the 89 students and ten out of the 23 tutors were interviewed. Volunteering ESL students, tutors, and ten university faculty were interviewed to explore their perceptions toward the writing center tutorials. Moreover, the researcher observed the two writing centers in which the study was conducted. Data analysis. This Mixed Methods Research study combined a quantitative design using surveys and a qualitative part utilizing interviews, and non-participatory observation. Therefore, the result of the survey administered were statistically analyzed using independent samples T-tests. After the interviews, coding an analysis began to investigate similarities and dissimilarities among the participants’ responses. Tables of frequency were designed to examine the range between outliers and calculate percentages of each respondent in comparison to the other group members. Each theme had a representative code, a formulated meaning, frequency of the respondent, and a significant statement asserting such theme. The themes were collected across all cases to show frequency. Findings. The findings of this study revealed that the writing center is effective in improving ESL tutees’ writing skills that may also be transferable to their future careers. Additionally, this study asserted that the non-directive tutoring approach, the commonly used in the U.S. writing centers, is not the only effective tutoring mode for all ESL tutees. Most tutors, according to this study, may not apply this prescriptive non-directive tutoring. Consequently, the study concluded that a reasonable balance between the tutoring dichotomies can make a difference with ESL students. Furthermore, the study emphasized that tutors need specialized ESL training to better assist and accommodate ESL tutees

Experimental and Theoretical Investigation of Vibro-Impact Triboelectric Energy Harvesters

Improving the efficiency of energy harvesting, by investigating different techniques to increase the harvester bandwidth, as well as by exploring the influencing factors and adjusting them to optimal setups. Towards this, multiple Vibro-impact energy harvesters were proposed in this study. First, a Two-Degree of Freedom (2DOF) Vibro-impact Triboelectric Energy Harvester with a single and a double impact configuration is proposed. Multi-modality and piecewise linearity were combined to improve the harvesting bandwidth of triboelectric energy harvesters utilizing two resonant frequencies. The harvester structure consists of a primary cantilever beam attached to a secondary cantilever beam through a tip mass in the opposite direction to the primary beam. An aluminum layer is attached to The bottom surface of the secondary beam, acts as an electrode of a triboelectric generator, and the other electrode is an aluminum layer bonded with Polydimethylsiloxane (PDMS) insulator, which is placed at some gap separation distance underneath the upper electrode to create a single impact structure. When the system is subjected to vibration excitation, the beams will vibrate, resulting in an impact between the triboelectric layers, generating an alternating electrical signal. To enhance the resonator\u27s bandwidth, we modified the structure to have a double impact by adding another triboelectric generator for the primary beam. The two beams are designed to have close frequencies, and under the effect of the impact, the bandwidth of the resonators is combined to create a very wide bandwidth. A 2DOF lumped parameter theoretical model was developed to extract the governing equations of both single and double impact systems. Then, a simulation analysis was conducted to examine the structure\u27s dynamic behavior at different excitation levels, separation distance, and surface charge density. Finally, experimental results were extracted to validate the simulation results. The result of this study can pave the way for an efficient energy harvester that can scavenge ambient vibrations over a wide range of excitation frequencies. Second, a harvester under rotational magnetic excitation is proposed for wind energy harvesting applications. The triboelectric beam generates electricity using magnetic impact-induced vibration. The triboelectric energy harvester consists of a clamped-clamped (CC) beam embedded in an outer case. The lower side of the beam acts as an upper electrode that will undergo a contact-separation motion with another lower electrode with a bonded PDMS layer. A permanent magnet will be attached to the beam\u27s upper side facing another magnet attached to a rotating rigid shaft blade at the same polarity. While the fan rotates, a repulsive magnetic force created between the two magnets will excite the CC-beam, leading to the contact-separation motion and generation of electricity. A Single-Degree of Freedom (SDOF) model is presented and simulated to extract the dynamic behavior and the generated electrical signal. The relationship between the output voltage and excitation rotational frequency is analyzed. In addition, the relationship between the output voltage and the distance between magnets and its effect on the bandwidth is also discussed. Finally, the effect of the surface charge density on the amplitude of the generated output voltage signal is examined. The rotational wind triboelectric energy harvester can effectively scavenge wind energy

Automatic Document Topic Identification Using Hierarchical Ontology Extracted from Human Background Knowledge

The rapid growth in the number of documents available to various end users from around the world has led to a greatly increased need for machine understanding of their topics, as well as for automatic grouping of related documents. This constitutes one of the main current challenges in text mining. We introduce in this thesis a novel approach for identifying document topics. In this approach, we try to utilize human background knowledge to help us to automatically find the best matching topic for input documents. There are several applications for this task. For example, it can be used to improve the relevancy of search engine results by categorizing the search results according to their general topic. It can also give users the ability to choose the domain which is most relevant to their needs. It can also be used for an application like a news publisher, where we want to automatically assign each news article to one of the predefined news main topics. In order to achieve this, we need to extract background knowledge in a form appropriate to this task. The thesis contributions can be summarized into two main modules. In the first module, we introduce a new approach to extract background knowledge from a human knowledge source, in the form of a knowledge repository, and store it in a well-structured and organized form, namely an ontology. We define the methodology of identifying ontological concepts, as well as defining the relations between these concepts. We use the ontology to infer the semantic similarity between documents, as well as to identify their topics. We apply our proposed approach using perhaps the best-known of the knowledge repositories, namely Wikipedia. The second module of this dissertation defines the framework for automatic document topic identification (ADTI). We present a new approach that utilizes the knowledge stored in the created ontology to automatically find the best matching topics for input documents, without the need for a training process such as in document classification. We compare ADTI to other text mining tasks by conducting several experiments to compare the performance of ADTI and its competitors, namely document clustering and document classification. Results show that our document topic identification approach outperforms several document clustering techniques. They show also that while ADTI does not require training, it nevertheless shows competitive performance with one of the state-of-the-art methods for document classification

Perspectives of the stakeholders of the public transportation system on ICT solutions applicability in the Free State, South Africa

Published Conference ProceedingsInformation Communication Technologies have recently been adopted by transportation systems around the world to improve their services. In adopting these technologies, the stakeholders‘ involvement and perceptions regarding ICT should be considered. This paper, considering the study area, reflects on the perceptions of different stakeholders of the public transportation system towards the introduction of ICT solutions to the system. The methodology adopted was to understand the expectations of drivers, passengers and operators on integrating ICT solutions into the public transportation system, focusing on mini-bus taxis and Interstate Bus Line buses. The significant results of the study show that ICTs are anticipated and long overdue development to the system but the stakeholders have varying expectations. These results reflect on the priorities of the stakeholders, i.e., passengers yearn for improved service quality; drivers are concerned with their working conditions while the operators‘ interests are profit motivated. This paper highlights the ICT interests of passengers, drivers and operators. It compares passengers‘ needs, in terms of technologies, to improve the public transportations system against what the operators are enthusiastic to provide