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RISS 인기검색어
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- 저자 : Jabbar, Tahseen A. (검색결과 95 건)
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Non-resonant piezoelectric transformer based power converter for ultra-low-power electronic devices
Jabbar, Hamid,Jung, Hyun Jun,Cho, Jae Yong,Sung, Tae Hyun Elsevier 2016 Sensors and actuators. A Physical Vol.244 No.-
<P><B>Abstract</B></P> <P>Piezoelectric transformer is used in its resonance frequency range to step-up or -down the input voltage. When the transformer is operated with alternating voltage in the non-resonance frequency range, which can be a few hertz, the transformer input works as an actuator, and the isolated output as a sensor to step-down the voltage. The output voltage has a linear relationship to its input the voltage. In this paper, the piezoelectric transformer in the non-resonant and low frequency range is represented by an equivalent circuit. A power converter that steps-down the mains voltage of 220V and 60Hz to supply power to a micro-watt consuming wireless sensor node is presented. This small size, fewer component, isolated, low EMI, and no inductive component converter has total input power consumption of 31mW with 3V and 11.2μW of output voltage and power respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Low-frequency and non-resonant behavior of Piezoelectric Transformer is presented. </LI> <LI> Equivalent circuit of non-resonant piezoelectric transformer is presented. </LI> <LI> The presented system can supply energy for ultra-low power electronics devices. </LI> <LI> Application specific design can improve efficiency and increase the output power. </LI> <LI> Overall power consumption of the system is very low (31mW). </LI> </UL> </P>
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Semantic Interoperability in Heterogeneous IoT Infrastructure for Healthcare
Jabbar, Sohail,Ullah, Farhan,Khalid, Shehzad,Khan, Murad,Han, Kijun WILEY INTERSCIENCE 2017 WIRELESS COMMUNICATIONS AND MOBILE COMPUTING Vol.2017 No.-
<P>Interoperability remains a significant burden to the developers of Internet of Things’ Systems. This is due to the fact that the IoT devices are highly heterogeneous in terms of underlying communication protocols, data formats, and technologies. Secondly due to lack of worldwide acceptable standards, interoperability tools remain limited. In this paper, we proposed an IoT based Semantic Interoperability Model (IoT-SIM) to provide Semantic Interoperability among heterogeneous IoT devices in healthcare domain. Physicians communicate their patients with heterogeneous IoT devices to monitor their current health status. Information between physician and patient is semantically annotated and communicated in a meaningful way. A lightweight model for semantic annotation of data using heterogeneous devices in IoT is proposed to provide annotations for data. Resource Description Framework (RDF) is a semantic web framework that is used to relate things using triples to make it semantically meaningful. RDF annotated patients’ data has made it semantically interoperable. SPARQL query is used to extract records from RDF graph. For simulation of system, we used Tableau, Gruff-6.2.0, and Mysql tools.</P>
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Jabbar Ali Zakeri,Morvarid Fattahi,Mohammad Mehdi Ghanimoghadam 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.6
One of the major problems of railroad deterioration is uneven settlement which occurs due to various reasons, including existence ofdefects in substructures, using non-homogenous ballast, or being poorly drained. Sometimes, because of these problems, sleepers remainfreely as a part of vertical displacement and contact the ballast with load increase. Different models have been presented for checking theeffect of hanging sleepers on the dynamic interaction of rail and train. In this paper, a mathematical model was developed for railwaytrack and differential rail displacement with supported and unsupported sleepers was compared by modeling sleepers such as partiallysupported ones. On this basis, the motion equations of the train-track system were solved considering the non-linearity of wheel/rail contactform and using numerical integration in the time domain. Longitudinal sections of the track model were coded in Matlab softwareand the effect of one, two, or three partially supported sleepers and various spacing of sleepers on the sleepers and rail displacement wasstudied and compared with that of the unsupported one. It was shown that, with increasing the sleeper spacing from 50 to 75 cm, raildisplacement increased from 7 to 22% in the unsupported sleeper and 5 to 8% in the partially supported sleeper. Additionally, rail displacementincreased from 13 to 74% by changing the number of the unsupported sleeper from 1 to 9. Also, it increased from 6 to 24% inthe partially supported sleepers.
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Application of 2D-infinite beam elements in dynamic analysis of train-track interaction
Jabbar Ali Zakeri,He Xia 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.5
Railway structure is a structure with an infinite length for which its modeling is usually carried out by accepting some assumptions for boundary conditions. In practice, there are various methods of modeling by forming equations of motions and dynamic analysis. One of these methods is modeling the railway track by finite element method. Generally in such modeling, a limited length of a track is modeled and executed by implementing some boundary conditions. Assortment of boundary conditions has an effect on dynamic responses. To reduce such effects, usually the length of the track is chosen to such a measure to minimize the dynamic responses of the end points of the track elements to zero. Doing so would cause an increase in the length of the track and hence add to an equation's degrees of freedom, volume of output and prolongation of analysis time. For this reason, a combination of finite elements and infinite beam elements (two end elements) has been proposed for railway track modeling. Also, matrices of mass, damping and stiffness of one infinite element which has been laid on a visco-elastic bed, have been calculated by implementing selected shape functions. Therefore, by applying two infinite beam elements on either side of the model, a railway track is formed like a beam on an elastic bed which creates the possibility of eliminating the boundary condition effects.
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Investigation on dynamic behavior of railway track in transition zone
Jabbar-Ali Zakeri,Vida Ghorbani 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.2
Railway track transition zone is a zone where track stiffness changes abruptly. This change occurs where the slab track connects to a conventional ballasted track, at the abutments of open-deck bridges, at the beginnings and ends of tunnels, at road and railway level crossings, and at locations where rigid culverts are placed close to the bottom of sleepers. In this paper, ballasted and slab tracks are simulated by two-dimensional model with two-layer masses. The transition zone is divided into three segments, each having a length of 6meters with different specification and stiffness. The model of track consists of a Timoshenko beam as a rail and slab, lumped mass as sleepers, and spring and damper as ballast, sub-grade, and rail pad. The results of the dynamic analysis are presented and compared in two circumstances – one considering the transition zone and the other its absence.
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Sensitive Analysis of Track Parameters on Train- Track Dynamic Interaction
Jabbar Ali Zakeri,He Xia 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.7
Dynamic behavior of railway tracks when trains are running is influenced by several factors, i.e. rolling stock, the components of superstructure and their specifications. Usually, features like the sleeper spacing, rail pad stiffness, bal-last damping and stiffness have an effect on the dynamic response of the track. The best method to study the dynamic behavior of the track is to model the track assembly and the train as a whole and carry out an analysis of dynamic inter-action. Such analysis makes the identification of the tracks dynamic behavior easer and helps to anticipate the deterio-presents tracktrain dynamic interaction without considering irregularity of the rail face. A sensitivity analysis was carried out on the selected model. The analysis was undertaken with the view of varying one of the mentioned parame-ters and the results were presented to further identify the deterioration of the track elements. The results indicate that reducing sleeper spacing, rail pad stiffness, ballast stiffness, and increasing ballast damping reduces wheel-rail, rail-sleeper, and sleeper - ballast contact forces. Keywords
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Jabbar Ali Zakeri,Rauf Abbasi 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.12
Sleeper is one of the most important components in a railway track system. Thus, for accurate analysis and design of concrete sleepers,knowledge of imposed loading pattern is necessary. Sandy desert areas are critical regions where loading status of concrete sleeper is different from other areas. In these areas, the influence of flowing sand grains between the ballast aggregates increase the stiffness of ballast layer; consequently, rail support modulus increases, so the received share of total axle load subsequently increases on the sleeper which is placed under the wheel load. On the other hand, the pressure distribution underneath the sleeper changes considerably. In this paper, the results of a field investigation about the variation of rail support modulus and also variation of loading pattern of concrete sleeper followed by the variation of bending moment of sleepers in sandy desert regions were presented.
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