Characterizing the Performance of a Ferrofluid-Based Electromagnetic Energy Harvester under Direct and Parametric Excitations

When a container carrying a magnetized ferrofluid is subjected to external mechanical stimuli, the sloshing motion of the magnetized ferrofluid generates a time-varying magnetic flux, which can be used to induce an electromotive force in a coil placed adjacent to the container. This process generates an electric current in the coil, and therewith, can be used to transduce external vibrations into electric energy providing a unique approach for vibration energy harvesting using liquid-state transduction materials. As compared to traditional vibratory energy harvesters that employ soli transduction elements, this approach offers several advantages including, but not limited to, conformability to different shapes and increased sensitivity to external excitations. In this dissertation, a bench-top experiment was first constructed to demonstrate the feasibility of the proposed concept for vibratory energy harvesting. A rectangular plastic container carrying ferrofluid was placed inside a pick-up coil which is wound around a ferrite core. The whole setup was mounted on an electrodynamic shaker table which provided a controlled acceleration at the containers base. The external magnetization is applied using permanent magnets with maximum magnetic field intensity of 92 mT. Series of experiments were carried out to determine the optimal configuration of coil windings with respect to the sloshing and magnetic field directions. It was found that the output power of the device increases an order of magnitude when the coil is wound perpendicular to the sloshing motion and magnetic field lines. For the optimal configuration determined experimentally, a nonlinear analytical model which governs the electro-magneto-hydrodynamics of the harvester was developed. An approximate analytical solution of the model was obtained using perturbation methods for two different types of excitation; namely for a case involving the primary resonance excitation of the first mode and a case involving the principle parametric resonance of the first two modes. For the case involving the primary resonance of the first mode, it was observed the approximate analytical solution fails to capture the qualitative behavior of the harvester’s response for some ferrofluid height to container width ratios. Upon further inspection, it was observed that for those critical height-to-width ratios, the sloshing conditions are such that a two-to-one internal resonance between the first two sloshing modes can be activated. To account for the internal resonance, a modified version of the perturbation solution was devised and used to obtain a solution of the governing equations capable of capturing the influence of the internal resonance on the dynamics. Overall, it was shown that the developed model is capable of capturing the qualitative behavior of the dynamics of the harvester for both cases of excitation and for various magnetic field distributions. It was observed that the orthogonality of the magnetic field distribution along the width the container to the shape of the mode being excited plays a critical role in determining the output power of the harvester. Specifically, regardless of the input excitation level and the size of the induced sloshing waves, very little energy can be harnessed from the environment when the magnetic field distribution is an even (odd) function of the containers width while the mode shape being excited is an odd (even) function of the width. It was shown that, unlike the primary resonance scenario, a threshold excitation level must be achieved in the principle parametric resonance case before the harvester can produce measurable voltage levels. This threshold increases with the strength of the applied magnetic field

The impact of digital learning resources on developing the educational process for faculty members at the PAAET

The study aimed to identify the impact of digital learning resources on the development of the educational process for faculty members at the PAAET, and its role in developing the academic capabilities of faculty members, including the areas of academic advancement and the quality of scientific research in the international publishing observatories, where the study applied the curriculum standards survey descriptive; The questionnaire was applied as a main tool to measure the impact of digital learning resources on the development of the educational process for faculty members through a sample of (78) faculty members from various disciplines. The study concluded that digital learning resources are one of the most important sources for developing the educational process for faculty members. Teaching, whether at the level of scientific research or academic promotion, with its active role in the development of the educational process. The study recommended the need to expand the use of faculty members for digital learning resources, with the need to intensify training courses and workshops in this field, with the need to develop policies and decisions related to their field of work, which In turn, it enhances the development of the educational process

Line and subdivision graphs determined by T4-gain graphs

Let T4 = (±1, ±i) be the subgroup of fourth roots of unity inside T, the multiplicative group of complex units. For a T4-gain graph Φ = (Γ,T4, ϕ), we introduce gain functions on its line graph L(Γ) and on its subdivision graph S(Γ). The corresponding gain graphs L(Φ) and S(Φ) are defined up to switching equivalence and generalize the analogous constructions for signed graphs. We discuss some spectral properties of these graphs and in particular we establish the relationship between the Laplacian characteristic polynomial of a gain graph Φ, and the adjacency characteristic polynomials of L(Φ) and S(Φ). A suitably defined incidence matrix for T4-gain graphs plays an important role in this contex

Indentation Mechanism in Rotary Hammer Forging Process: Analytical and Numerical Approach

Rotary hammer forging process is getting popular since it has many advantages comparing to the conventional forging process. The mechanism of the movement in term of orbital motion of the conical upper die become concern of this research. This article present the three stages of the modelling of the rotary hammer forging. The first stage is the development of the orbital motion of the conical upper die. Three-dimensional CAD model of the conical upper die was developed to determine the orbital motion as a function of the four parameters: Nutation, Precession, Spin and Rocking-Die mechanism. A reasonably accurate design of the conical upper die and the workpiece had been developed based on motion because of interaction of conical upper die and upper part of workpiece geometries. The behaviour of orbital motion with any active combination of those four parameters was observed. The second stage was the development of the conical upper die with the specific feature in order to generate a product with an unsymmetrical shape of upper part of the product. The sequence and mechanism of the formation of the upper part of product were generated. The third stage was the analysis of the stress strain state during the formation of the upper part of the workpiece. An elastic-plastic, dynamic analysis of 3D rotary hammer forging mechanism with the concern at the workpiece and their interaction with a model of dies have been performed. Verification of the indentation mechanism of the rotary hammer forging had been done by validating the result with the existing experimental results

Individuals with obesity and COVID-19: A global perspective on the epidemiology and biological relationships

The linkage of individuals with obesity and COVID-19 is controversial and lacks systematic reviews. After a systematic search of the Chinese and English language literature on COVID-19, 75 studies were used to conduct a series of meta-analyses on the relationship of individuals with obesity–COVID-19 over the full spectrum from risk to mortality. A systematic review of the mechanistic pathways for COVID-19 and individuals with obesity is presented. Pooled analysis show individuals with obesity were more at risk for COVID-19 positive, >46.0% higher (OR = 1.46; 95% CI, 1.30–1.65; p < 0.0001); for hospitalization, 113% higher (OR = 2.13; 95% CI, 1.74–2.60; p < 0.0001); for ICU admission, 74% higher (OR = 1.74; 95% CI, 1.46–2.08); and for mortality, 48% increase in deaths (OR = 1.48; 95% CI, 1.22–1.80; p < 0.001). Mechanistic pathways for individuals with obesity are presented in depth for factors linked with COVID-19 risk, severity and their potential for diminished therapeutic and prophylactic treatments among these individuals. Individuals with obesity are linked with large significant increases in morbidity and mortality from COVID-19. There are many mechanisms that jointly explain this impact. A major concern is that vaccines will be less effective for the individuals with obesity

The economic burden of overweight and obesity in Saudi Arabia

ContextThe prevalence of overweight and obesity in Saudi Arabia has been rising. Although the health burden of excess weight is well established, little is known about the economic burden.AimsTo assess the economic burden-both direct medical costs and the value of absenteeism and presenteeism-resulting from overweight and obesity in Saudi Arabia.Settings and designThe cost of overweight and obesity in Saudi Arabia was estimated from a societal perspective using an epidemiologic approach.Methods and materialsData were obtained from previously published studies and secondary databases.Statistical analysis usedOverweight/obesity-attributable costs were calculated for six major noncommunicable diseases; sensitivity analyses were conducted for key model parameters.ResultsThe impact of overweight and obesity for these diseases is found to directly cost a total of $3.8 billion, equal to 4.3 percent of total health expenditures in Saudi Arabia in 2019. Estimated overweight and obesity-attributable absenteeism and presenteeism costs a total of$15.5 billion, equal to 0.9 percent of GDP in 2019.ConclusionsEven when limited to six diseases and a subset of total indirect costs, results indicate that overweight and obesity are a significant economic burden in Saudi Arabia. Future studies should identify strategies to reduce the health and economic burden resulting from excess weight in Saudi Arabia

Effect of rice husk ash addition on the physical properties of soda-lime-silica glass for building glass and window

One of the promising raw materials in producing glass is rice husk (RH), which contains about 90% of silica and is usually burnt in an open area which contributed to serious air pollution problems. The environmental issues of RH could be resolved by utilizing rice husk ash (RHA) as a silica source in the glass manufacturing process. The main objective of this research is to develop an ecofriendly Soda-Lime-Silica - Rice Husk Ash (SLS-RHA) glass for the application of building glass and window. Three main experiments were conducted; morphology test, ultrasonic velocities testing and Rockwell hardness test to assess the microstructure, elastic and mechanical behaviour of the developed SLS-RHA glass. Response surface methodology (RSM) was used to design the experiments incorporating two factors; such as the ratio of SLS to RHA and their interrelationship; and the effect on glass hardness properties were analysed using analysis of variance (ANOVA). From the morphology analysis, the addition of RHA to the glass former matrix increased the porosity of the glass which influenced the elastic properties of the newly developed glass. It was observed that sample two with 5% RHA wt. addition performed the finest under elastic properties test and the longitudinal and shear modulus of RHA glass decrease with the increased of RHA content. Sample with 5% of RHA possessed high and medium elastic properties, which make it easier to bend rather than elongate, less stiff, tough at a certain direction, and has low rigidity. The value of the longitudinal modulus decreased 7.12% with the addition of 10% RHA wt. Finally, for the hardness test, based on the observation from HRF, HRB and HRG contour plots which showed that the hardness values for each sample decreased as the RHA percentage increased in the SLS glass system. The hardness of the glass decreased with an increase in the addition of RHA content due to elastic deformation. The optimal solution obtained from ANOVA for the combination of RHA and SLS is SLS (A) 29.589% wt. and RHA (B) 0.031% wt. This formulation provided the results of 130.588 for HRF, 124.844 for HRB and 120.098 for HRG. It can be summarized that the use of silica from RHA efficiently improved the bulk modulus while maintaining a lower Young’s modulus value of the glass. This resulted in improved impact resistance of the glass due to a slower decelerated in smaller stress acting on the glass even though the glasses are less stiff. In this research, RHA proved to be a good silica source alternative for the glass manufacturing process, which can potentially improve the melting process temperature indirectly helps to reduce the cost of the manufacturing process

Problems of Female Preservice Kuwaiti English Language Teachers During the Practicum Course

Knowledge of pre-service teachers' difficulties and the obstacles they face during their practicum is supremely important to designing and implementing a successful field experience. Based on this, the current study explored and discussed the most frequent problems that Kuwaiti English language pre-service teachers face during their practicum course. The purpose of this research is to learn more about the challenges and obstacles that female pre-service Kuwaiti English language teachers (n = 45) may experience throughout their practicum period. To achieve the intended outcomes, the study used a qualitative approach. Semi-structured interviews were conducted with female pre-service English language teachers at the college of Basic Education in Kuwait. The College of Basic Education plays a key role in providing qualified female teachers to the Ministry of Education through a training program that prepares potential English instructors to fulfil the career requirements of English instructors. According to the findings of the research, different issues have been aroused by the participants as they have complained about some aspects of the practicum course, including preparing lesson plans and workload, relationship with colleagues in the department, classroom management (especially dealing with students who have special cases), and academic supervisors. Interpretations of the results and recommendations are discussed in relation to the context of the study

Problems of Female Preservice Kuwaiti English Language Teachers During the Practicum Course

Knowledge of pre-service teachers' difficulties and the obstacles they face during their practicum is supremely important to designing and implementing a successful field experience. Based on this, the current study explored and discussed the most frequent problems that Kuwaiti English language pre-service teachers face during their practicum course. The purpose of this research is to learn more about the challenges and obstacles that female pre-service Kuwaiti English language teachers (n = 45) may experience throughout their practicum period. To achieve the intended outcomes, the study used a qualitative approach. Semi-structured interviews were conducted with female pre-service English language teachers at the college of Basic Education in Kuwait. The College of Basic Education plays a key role in providing qualified female teachers to the Ministry of Education through a training program that prepares potential English instructors to fulfil the career requirements of English instructors. According to the findings of the research, different issues have been aroused by the participants as they have complained about some aspects of the practicum course, including preparing lesson plans and workload, relationship with colleagues in the department, classroom management (especially dealing with students who have special cases), and academic supervisors. Interpretations of the results and recommendations are discussed in relation to the context of the study

Higher Education and Smart Education System: The Impact of Learning Style and Environmental Characteristics in the State of Kuwait

The purpose of this research is to explore the implementation of smart education systems and approaches in the State of Kuwait’s higher education. The determinants of the successful smart education system, particularly learning styles of students and the learning environment characteristics also investigated. The advancement of information and communication technologies has paved the shifts in learning and teaching with countries such as Kuwait have progressively integrated ICTs and smart technologies into their education systems. This research conducted a systematic literature review on smart education systems in Kuwait and the determinants of its successful implementation.&nbsp; A systematic keyword strategy was utilized for secondary data search from databases and archives, including university e-library and scholarly scientific research and various article database. A systematic content analysis was conducted by analysing the gathered secondary data.&nbsp; Findings from this study suggested that various tools and technologies used in implementing smart education in Kuwait however, learning styles and learning environmental characteristics had significantly influenced the success of the adoption of smart education in Kuwait’s higher education. The findings of this study demonstrated practical implications in higher education, especially in terms of designing smart education systems in emphasizing the learning styles of students as well as the necessary learning environment factors for successful smart education. The smart education systems to facilitate flexible and efficient learning of higher education students in Kuwait along with learning styles of students and learning environmental factors are considered in designing smart education