13 research outputs found
The role of Islam and natural resources in current Mali political turmoil
No full textIn the recent times, the Republic of Mali has been striving to restore peace and harmony in the state. The conflict initiated by
insurgent Islamist groups fighting against the Malian government for independence in northern Mali. The revolt against the
government is associated with the implementation of shariah laws. Despite the current decrepit political condition in Mali it
seems to be a site of attraction of Western military intervention. This paper studies the role of religion and natural resources in
the conflict. Mali is one of the poorest countries in the world but in reserve it has one of the largest amounts of mineral
deposits including uranium and other energy related resources. The significance of this paper is that it critically analyses the
legality, motives and purpose of French intervention in Malian conflict and direct US support for it
Timbuktu civilization and its significance in Islamic history
No full textTimbuktu civilization began as a seasonal settlement for trade caravans in the early 11th century. It later flourished in trade and
as one of the early African centres of Islamic culture. This paper reviews the trend of Timbuktu civilization from prehistoric
period up to the current state of its political impact of the region. The paper further focuses on the role Timbuktu played in
African history by serving as academic and commercial centre. The significant of this paper is to reveal the fact that Africa has
a long Islamic civilization. The paper provides evidences from reliable sources of the symbolic representation of the impact and
influence of the early schools and universities between 11th and 15th century that existed in West Africa. The manuscript of
Timbuktu serves as a living testimony of the highly advanced and refined civilization in Africa during the middle ages. The
history of monuments, artefacts as well as architectural land marks that signifies the historical origin of this ancient city is
presented. The early heroes that stood firm towards the development and civilisation of Timbuktu are outlined. Analysis of the
development as well as the factors that led to the civilization is presented in this paper
A piezoelectric based energy harvester with magnetic interactions: modelling and simulation
No full textIn recent years, utilizing kinetic energy in mechanical vibrations has become an interesting area of research. This is due to ubiquitous sources of vibration energy, coupled with the ever increasing demands to power wireless sensing electronics and Microelectromechanical (MEMs) devices with low energy requirements. Thus, researchers have ventured into developing different system configurations with the aim of harvesting vibration energy to power these devices.
Cantilever beam systems with piezoelectric layer have been used as vibration energy scavengers due to their abilities of converting kinetic energy in vibrating bodies into electrical energy, whereas permanent magnets have been used to improve their performance. The only unresolved challenge is to develop energy harvesters that can produce optimum energy at a wider bandwidth. In this study, a mathematical model of a system of cantilever beams with piezoelectric layers having a magnetic coupled tip mass is proposed. The lumped parameter model of the harvester is developed to estimate the power output of the proposed harvester, and to visualise the effect of magnetic coupled
tip mass in widening the frequency bandwidth of the energy harvester. Preliminary Simulation results using MATLAB have however shown the effectiveness of the proposed system
Piezoelectric based vibration energy harvester with tip attraction magnetic force: modeling and simulation
No full textIn recent times, vibration based energy harvesting
has drawn attention of many researchers worldwide. This is due to advancement in Microelectromechanical (MEM) devices and wireless sensors with power requirements in range of microwatts-milliWatts; hence vibration energy sources have promising potentials for such demands. Thus, many attempts were made by researchers to develop different system configurations for effective utilization of vibrations that happen all around us. Cantilever beams with piezoelectric
patches are used to harness kinetic energy from mechanical vibrations. This paper is aimed at studying the effect of adding a magnetic force at the tip mass, which is also a magnet with opposite pole, on power output of the energy harvester. The additional attraction force between the tip mass and the fixed magnet influences stiffness of the system, whilst tuning the natural frequency. Mathematical equation to depict the
relationship between tuned natural frequency and distance between permanent magnet is derived. The lumped parameter model for the harvester with single fixed magnets aligned with magnetic tip mass is derived. MATLAB software is used to perform the simulation study on influence of the magnet on the harvester
A review on recent advances of CNTs as gas sensors
No full textPurpose - This review paper aims to focus on recent advances of carbon nanotubes (CNTs) to produce gas sensors. Gas sensors are widely used for monitoring hazardous gas leakages and emissions in the industry, households and other areas. For better safety and a healthy environment, it is highly desirable to have gas sensors with higher accuracy and enhanced sensing features. Design/methodology/approach - In this review, the authors focus on recent contributions of CNTs to the technology for developing different types of gas sensors. The design, fabrication process and sensing mechanism of each gas sensor are summarized, together with their advantages and disadvantages. Findings - Nowadays, CNTs are well-known materials which have attracted a significant amount of attention owing to their excellent electrical, electronic and mechanical properties. On exposure to various gases, their properties allow the detection of gases using different methods. Therefore, over recent years, researchers have developed several different types of gas sensors along with other types of sensors for temperature, strain, pressure, etc. Originality/value - The main purpose of this review is to introduce CNTs as candidates for future research in the field of gas sensing applications and to focus on current technical challenges associated with CNT-based gas sensors
Comparative study of conventional and magnetically coupled piezoelectric energy harvester to optimize output voltage and bandwidth
No full textEnergy harvesting has experienced significant
attention from researchers globally. This is due to the quest to power remote sensors and portable devices with power requirements of tens to hundreds of μW. Hence, ambient vibration energy has the potential to provide such power demands. Thus, cantilever beams with piezoelectric materials have been utilized to transduce mechanical energy in vibrating bodies to electrical energy. However, the challenge is to develop energy harvesters that can harvest sufficient amount of energy needed to power wireless sensor
nodes at wide frequency bandwidth. In this article, piezo-
electric energy harvester (PEH) beams with coupled mag-
nets are proposed to address this issue. With macro fiber composite as the piezoelectric transducer, mathematical models of different system configurations having magnetic couplings are derived based on the continuum based model. Simulations of the system dynamics are done using numerical integration technique in MATLAB software to study the influence of magnetic interactions in generating power and frequency bandwidth due to base excitations at low frequency range. Experimental results comparing conventional system and the proposed piezoelectric beam configurations with coupled magnets are also presented. Finally, the optimal beam separation distance between the magnetic oscillator and PEH is presented in this work
Dynamic Behavior of Sandwich Structures with Magnetorheological Elastomer: A Review
No full textMagnetorheological (MR) materials are classified as smart materials that can alter their rheological features once exposed to peripheral magnetic fields. MR materials have been a standard and one of the primary smart materials for the last few decades due to their outstanding vibration control performance in adaptive sandwich structures and systems. This paper reviews the vibration suppression investigations of flexible constructions using MR elastomers (MREs). In relations of field-dependent controllability, physical features such as stiffness and the damping of different geometrical structures integrated with the core layer of MREs are explored. The veracity of the knowledge is discussed in this article, whereby sandwich structures with different MR treatment configurations are analyzed for free and forced vibration, MRE sandwich structures are analyzed for stability under different working conditions, and the optimal positions of fully and partially treated MRE sandwich structures for improved vibration control are identified. MR materials′ field-dependent stiffness and damping characteristics are also discussed in this article. A few of the most noteworthy research articles over the last several years have been summarized
Optimal strain-deflection analyses of a wedge edged beam for enhanced vibration energy scavenging in patch-like harvester
No full textDamping and Stiffness Analysis of Sandwich Beam with 3D-Printed Honeycomb Core Filled with Magnetorheological Elastomer (MRE): An Experimental Approach
No full textThe current study focuses on the production and experimental examination of sandwich beams consisting of an aluminum face sheet and 3D-printed honeycomb cores that are filled with magnetorheological elastomer (MRE). These cores are loaded with different ratios of (75/25)% and (50/50)% elastomer and magnetic particles, measured by weight. In order to ascertain the dynamic characteristics of sandwich beams, the constructed specimens were subjected to classic shock (free vibration) experiments, and these experiments were conducted under two conditions: with and without the application of a changing magnetic field at the free end and center of the beam. The results of the experiments suggest that the attenuation of the damping ratio exhibited satisfactory performance, particularly with respect to the structures that were being examined. The sandwich beam constructions proposed exhibited the ability to alter the damping ratio, damping coefficient, and stiffness through the application of a magnetic field. Nevertheless, an escalation in the applied magnetic field resulted in a reduction in stiffness values, while the values of the damping ratio and damping coefficient increased. Furthermore, significant variations in damping were observed when the magnets were located in the central regions of the structures
Static and Modal Analysis of Sandwich Beam Structure with Magnetorheological Honeycomb Core
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