Performance evaluation of a magnetorheological fluid damper using numerical and theoretical methods with experimental validation

Magnetorheological (MR) fluids which can exhibit substantial reversible rheological changes under the excitation of external magnetic fields, have enabled the construction of many novel and robust electromechanical devices in recent years. Generally, Bingham plastic model is utilized for the estimation of the characteristics of MR fluids. However, when the geometry and design of the MR device as well as the rheological conditions of the fluid itself become complicated due to the engineering application requirements, the accuracy of Bingham plastic model, which simplifies the relation between the fluid shear stress, and shear rate into a linear function, is degraded. In this paper, a multi-degree-of-freedom (MDOF) magnetorheological fluid damper with a novel ball-and-socket structure was developed, which was aimed to enhance the human shoulder rehabilitation treatment. The performance of the proposed smart device with its complex design was estimated numerically using a finite element method (FEM) with a Herschel-Bulkley model and theoretically with a model that is based on a Bingham plastic fluid characteristics. The performance of the developed damper was validated experimentally using a dedicated testing facility for various input conditions. It was found that the FEM simulations with the Herschel-Bulkley model showed a better agreement with the experimental results in comparison with the theoretical predictions which were somewhat degraded with the employed Bingham plastic model

Egyptian public diplomacy: Past performance and future strategies ( case study)

This study aims to explore whether the types of Egyptian public diplomacy, if any, follow strategies, content, and priorities of new public diplomacy by analyzing public diplomacy strategies followed by the two of main informational bodies in the Egyptian state: the State Information Service (SIS), and the public diplomacy division in the Ministry of Foreign Affairs (MFA). The study advances a theoretical framework designed to help find a connection between strategies followed by public diplomacy institutions and agenda-building function of those institutions. The analysis reflected the lack of strategic planning in the two institutions to reach and influence foreign publics. Findings proposed that the main communication strategies in the SIS and MFA related to media relations and adopting reactive approaches to counter negative media coverage about the country in foreign media. A set of recommendations were introduced in a search for enhanced public diplomacy structure with more effective strategies to properly communicate with the international communit

Development of a Novel Latching-Type Electromagnetic Actuator for Applications in Minimally Invasive Surgery

Single-port laparoscopic surgery (SLS), which utilises one major incision, has become increasingly popular in the healthcare sector in recent years. However, this technique suffers from several problems particularly the inability of current SLS instruments to provide the optimum angulation that is required during SLS operations. In this paper, the development of a novel latching-type electromagnetic actuator is reported, which is aimed to enhance the function of SLS instruments. This new actuator is designed to be embedded at selected joints along SLS instruments to enable the surgeon to transform them from their straight and slender shape to an articulated posture. The developed electromagnetic actuator is comprised of electromagnetic coil elements, a solid magnetic shell, and a permanent magnet used to enhance the magnetic field interaction along the force generation path and also to provide the latching effect. In this investigation, electromagnetic finite element analyses were conducted to design and optimise the actuator’s electromagnetic circuit. In addition, the performance of the new actuator was numerically and experimentally determined when output magnetic forces and torques in excess of 9 N and 45 mNm, respectively together with an angulation of 30° were achieved under a short pulse of current supply to the magnetic circuit of the actuator

Remodeling Teachers' and Students' Roles in Self-directed Learning Environments: The Case of Saudi Context

Traditional classrooms are markedly teacher-centered. EFL learners are largely urged to commit themselves to communicative learning environments which help them enhance their language performance. Self-directed learning is one of the approaches which proved to be highly effective in Foreign Language Learning (FLL). EFL teachers are usually encouraged to adopt self-directed learning practices in order to improve students’ linguistic competence and performance. Recently, many Saudi universities integrated self-directed learning mode into EFL instruction. However, students' language performance, which is crucial to finding a job opportunity in labor market, is below the desired level. The study aims at remodeling teachers' and students' roles in light of students’ perceptions of English self-directed learning. To achieve this ultimate goal, a questionnaire survey is administered and follow-up semi-structured interviews are held. Results showed that both male and female students have generally positive attitudes towards self-directed learning. However, many of them have real problems with understanding the nature of self-directed learning and how they should use it effectively. Therefore, both institutions and teachers are recommended to improve students’ understanding and awareness of self-directed learning modes, and to rethink their roles

Solving fully neutrosophic linear programming problem with application to stock portfolio selection

Neutrosophic set is considered as a generalized of crisp set, fuzzy set, and intuitionistic fuzzy set for representing the uncertainty, inconsistency, and incomplete knowledge about the real world problems. In this paper, a neutrosophic linear programming (NLP) problem with single-valued trapezoidal neutrosophic numbers is formulated and solved. A new method based on the so-called score function to find the neutrosophic optimal solution of fully neutrosophic linear programming (FNLP) problem is proposed. This method is more flexible than the linear programming (LP) problem, where it allows the decision maker to choose the preference he is willing to take. A stock portfolio problem is introduced as an application. Also, a numerical example is given to illustrate the utility and practically of the method

A method to solve two-player zero-sum matrix games in chaotic environment

This research article proposes a method for solving the two-player zero-sum matrix games in chaotic environment. In a fast growing world, the real life situations are characterized by their chaotic behaviors and chaotic processes. The chaos variables are defined to study such type of problems. Classical mathematics deals with the numbers as static and less value-added, while the chaos mathematics deals with it as dynamic evolutionary, and comparatively more value-added. In this research article, the payoff is characterized by chaos numbers. While the chaos payoff matrix converted into the corresponding static payoff matrix. An approach for determining the chaotic optimal strategy is developed. In the last, one solved example is provided to explain the utility, effectiveness and applicability of the approach for the problem.Abbreviations: DM= Decision Maker; MCDM = Multiple Criteria Decision Making; LPP = Linear Programming Problem; GAMS= General Algebraic Modeling System

Diagnostics-in-a-Suitcase: Development of a portable and rapid assay for the detection of the emerging avian influenza A (H7N9) virus

Background: In developing countries, the necessary equipment for the diagnosis is only available in few central laboratories, which are less accessible and of limited capacity to test large numbers of incoming samples. Moreover, transport conditions of samples are inadequate and therefore lead to unreliable results. Objectives: The development of rapid, inexpensive, and simple test would allow mobile detection of viruses. Study Design: A suitcase laboratory “Diagnostics-in-a-Suitcase” (56 × 45.5 × 26.5 cm) containing all necessary reagents and devices to perform reverse transcription recombinase polymerase amplification (RT-RPA) assay was developed. As an example, Two RT-RPA assays for the detection of hemagglutinin (H) and neuraminidase (N) genes of the novel avian influenza (H7N9) virus were established. Results: Sensitivities were 10 and 100 \{RNA\} molecules for the \{H7\} and the \{N9\} RT-RPA assays, respectively. Assays were performed at a single temperature (42 °C). Results were obtained within 2-7 minutes. The \{H7N9\} RT-RPA assays showed neither a cross-detection of any other respiratory viruses affecting humans and/or birds nor of the human or chicken genomes. All reagents were used, stored, and transported at ambient temperature, i.e. cold chain independent. In addition, the Diagnostics-in-a-Suitcase was operated by a solar power battery. Conclusions: The developed assay protocol and mobile setup performed well. Moreover, it can be easily implemented to perform diagnosis at airport, quarantine stations, or farms for rapid on-site viral nucleic acid detection