Computer analysis of molten steel flow and application to design of nozzles for continuous casting system

In steel continuous casting system, nozzles have an important role on the flow rate control of the molten steel and the elimination of the inclusions etc. Based on the fundamental principle of hydrodynamics, the optimal nozzle bore profile was determined for both tundish (TD) upper nozzle and submerged entry nozzle (SEN) with aiming to suppress the turbulence with high kinetic energy generated in the flow of the molten steel. A simulation by flow analysis using computational fluid dynamics (CFD) and a water model experiment were performed and clarified that the turbulence with high kinetic energy could be minimized in the nozzles with newly devised inner bore profile. The actual nozzle devised was manufactured and tested in the steel works with satisfying results. The adhesion of the alumina inclusions to the both nozzles is reduced by lowering the turbulent kinetic energy since the energy loss is minimized at the part. Both stability in the operation and quality of the steels have been brought by the present development.

Dynamic model for high-speed rotors based on their experimental characterization

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

Teacher and student views on educational robotics: The Pan-Hellenic competition case

The present work is an observational study recording the teachers’ and students’ attitudes from the Pan-Hellenic Educational Robotics (ER) competition. The study investigates the benefits of students’ involvement with robotics regarding skills, motivation and learning. Additionally, it is researched whether ER should be introduced in the compulsory curricula. A qualitative methodology was used with teachers. Although the sample was relatively small, the results were quite homogeneous showing a very high level of engagement and motivation of teachers and students. A mainly quantitative methodology was used to gather data from students. The results show that there are numerous benefits for students: they seem to increase their collaboration, problem solving and creativity skills; understand STEM concepts in computer science and engineering, and gaining programming knowledge in particular. Also, most of the teachers and many of the students consider that ER should be part of the compulsory curriculum. Under certain conditions, ER could be an essential part of the school program, as it can bring together young people from all over the world to learn and develop important 21st century skills.

Learners’ perceptions of instructor feedback in e-learning courses – findings from HBMSU, United Arab Emirates

Instructor feedback is constructive and specific information provided by an instructor to a learner on his or her course work and/or class contributions in relation to the course objectives and expectations. Effective instructor feedback is particularly important in online learning as learners are more likely to withdraw from online learning environments due to delayed, or inadequate feedback, compared with students enrolled in physical classes. Not all learners are equally active, and there are indeed learners who hardly take an active part in online course activities -the so-called lurkers. Courteous instructor feedback to such learners on their limited participation has been shown to improve learners’ participation in online courses. Diligent learners engaged in online learning programs expect feedback to be contextual, supportive, constructive, timely, substantive, summative and formative. This study examined the perceptions of 66 undergraduate and postgraduate learners on feedback provided in eight online courses facilitated by the same instructor at the School of Health and Environmental Studies, Hamdan Bin Mohammed Smart University, Dubai, UAE between August 2014 and December 2015. Data collection from learners was anonymized and participation was voluntary. The survey sought to elicit learners’ perceptions on the extent to which feedback provided in specified courses were motivational, timely, frequent, supportive, and individualized. A polytomous Rasch model was utilized to analyze the data with Winsteps and STATA. Analysis of the 20 survey questions revealed a real person reliability of 0.82 and a Cronbach Alpha test reliability of 0.96, suggesting that the scale discriminates well between the persons. The real item separation reliability of 0.77 suggests that the questions are reliable in measuring the specified items. Descriptive analyses revealed general agreement among the majority of learners on the effectiveness of feedback provided by the instructor, although Infit and Outfit Z-standard deviation statistics revealed two questions with unexpected rare (i.e. “mostly disagree” or “completely disagree”) extremes in several learners’ responses. Unlike single questions related to learner feedback in most Student Perception of Teaching Surveys, this survey instrument comprehensively explores the dimensions of instructor feedback, aspects of which may not be previously known to learners or instructors. Our results indicate that systematic collection and analysis of learners’ feedback comments have a strong potential to enhance feedback competencies of course facilitators, as well as provide a common platform for both learners and course facilitators vis-à-vis the diverse objectives of instructor feedback.

Directions of Development of Intelligent Real Time Video Systems

Real time video systems play a significant role in many fields of science and technology. The range of their applications is constantly increasing together with requirements to them, especially it concerns to real time video systems with the feedbacks. Conventional fundamentals and principles of real-time video systems construction are extremely redundant and do not take into consideration the peculiarities of real time processing and tasks, therefore they do not meet the system requirements neither in technical plan nor in informational and methodical one. Therefore, the purpose of this research is to increase responsiveness, productivity and effectiveness of real time video systems with a feedback during the operation with the high-speed objects and dynamic processes. The human visual analyzer is considered as a prototype for the construction of intelligent real time video systems. Fundamental functions, structural and physical peculiarities of adaptation and processes taking place in a visual analyzer relating to the information processing, are considered. High selectivity of information perception and wide parallelism of information processing on the retinal neuron layers and on the higher brain levels are most important peculiarities of a visual analyzer for systems with the feedback. The paper considers two directions of development of intelligent real time video systems. First direction based on increasing intellectuality of video systems at the cost of development of new information and dynamic models for video information perception processes, principles of control and reading parameters of video information from the sensor, adapting them to the requirements of concrete task, and combining of input processes with data processing. Second direction is associated with the development of new architectures for parallel perception and level-based processing of information directly on a video sensor matrix. The principles of annular and linear structures on the neurons layers, of close-range interaction and specialization of layers, are used to simplify the neuron network.

Design and Implementation of Task Reprocessing on Medium-large Multi-core Architecture

EDF-Based real-time scheduling approach is one of the efficient way of scheduling the recurrent real-time tasks in both soft real-time and hard real-time systems. EDF algorithms entile heavy overhead due to lower scheduling and huge migration. In this paper, an exploratory procedure has been presented for reprocessing of neglected task sets and also examine, whether an improved heuristic set attributed as Enhanced shared CAche Performance (ENCAP) can improve the shared cache performance which processes the task set based on Earliest-Deadline-First (EDF). An Object-Oriented real-time code reusable scheduling components which is designed from the scratch referred as LITMUSRT has been used to test the efficiency and average-case accomplishments where per task utilizations are shortened and overall utilization are not restricted. We also discuss the implementation and experimental evaluation of Task-Repo procedure for co-scheduling task sets, under the utilization of 50-60% (per-task) on small to medium-large multicore LINUX SYSTEM.

Classification of Cloud Systems Cyber-security Threats and Solutions Directives

Cloud computing cyber security is a subject that has been in top flight for a long period and even in near future. However, cloud computing permit to stock up a huge number of data in the cloud stockage, and allow the user to pay per utilization from anywhere via any terminal equipment. Among the major issues related to Cloud Computing security, we can mention data security, denial of service attacks, confidentiality, availability, and data integrity. This paper is dedicated to a taxonomic classification study of cloud computing cyber-security. With the main objective to identify the main challenges and issues in this field, the different approaches and solutions proposed to address them and the open problems that need to be addressed.

A User-PC Computing System as Ultralow-cost Computation Platform for Small Groups

Recently, a personal computer (PC) has rapidly evolved the computing ability due to the highest CPU clock, more CPU cores, and the larger memory. Then, the collection of idling CPU cycles in conventional PCs of the members in a group such as a university laboratory significantly enhances the level of parallel computing platform with very small costs. This low-cost computation environment is of great interest in schools, especially in developing countries. To realize this concept, in this paper, we propose a User-PC Computing (UPC) system based on the master-worker model. First, we present the design and implementation of the UPC master using Linux and for the UPC worker with both Linux and Windows. Then, because the job scheduling takes a key role in determining the overall computing performance, we present an efficient job scheduling method using performance measurement results of worker PCs by benchmark programs, in addition to a conventional round-robin one. We verify the effectiveness of our proposed UPC system through experiments using several benchmark and application programs.

A Review on the Components of EEG-based Motor Imagery Classification with Quantitative Comparison

Motor Imagery (MI) is a voluntary modulation of brain signals for specific action without real limb movement. It is essential to classify MI signal to design a brain computer interface (BCI). BCI involves a number of signal processing steps, and a lot of techniques have been developed for each step. There can be numerous combinations of these techniques at different steps that can be employed to design a BCI. This work focuses on MI-based BCI using EEG signal and reviews the existing techniques. More importantly, a detailed comparative study is performed to explore the important combinations of methods by comparing their performance quantitatively. Often a method, which performs very good in one combination, can be bad performer in other combinations and it is a dilemma for the researchers to select appropriate methods for their desired BCI application.In our performance analysis, we have systematically included the variations of methods in each step of BCI such that it gives idea to BCI researchers how each method in one step fits best with specific combinations of methods in other steps. We have shown that how much each step is sensitive towards overall performance of the BCI system.We hope that this work helps, especially for new researchers, to provide a better guideline for designing more efficient BCI system.

Method of Evaluating the Weights of Software Quality Measures and Indicators

Nowadays the actual task is evaluating the mutual influences of the software quality characteristics and subcharacteristics by the measures and software quality metrics – by the indicators. The aim of this study is the development of the method of evaluating the weights of software quality measures and indicators. The first time developed method of evaluating the weights of the software quality measures and indicators differs from known methods that: considers the correlation of software quality subchcaracteristics by the measures and metrics by the indicators, calculates the weights of exactly measures and indicators, provides the conclusion about the presence of which measures and indicators in the software requirements specification (SRS) is necessary for the appropriate level of veracity of the software quality assessment. The weights of the software quality measures and indicators provide the sorting of all missing in the SRS measures and indicators in descending of their significance (in descending of their weights), i.e. the priority of their further addition in the SRS.