| 1. |
- Alhelfi, Ali Kadhim Hadi, et al.
(författare)
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Assessing Learning in Higher Education
- 2012
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Rapport (populärvet., debatt m.m.)abstract
- Assessment is a key activity within the higher education system. From the student´s perspective, assessment shapes what is to be learned; from the perspective of the educator it gives clear inputs about the quality of learning. Thus, as defined by the term, ‘Constructive alignment’, by careful planning of the assessment strategy and wise selection of the assessment methods, the teaching-learning experience can be designed in an aligned manner towards the achievement of the learning outcomes. Although, defined in different ways, the basic purpose of assessment is to work as a feedback tool to both, students and teachers, to improve the student learning. In this work, we review and comment on theoretical aspects of assessment including its significance and characteristics. Moreover, some important considerations regarding the design of the assessment activities are presented, together with the description of some methods for assessing learning. With this work we would like to invite the reader to reevaluate the significance of assessment within the learning experience, and by this, hopefully the educator is “inspired” to improve the assessment activities in the classroom or another less conventional learning space.
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| 2. |
- Alhelfi, Ali Kadhim Hadi, et al.
(författare)
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Bubble Power and Ultrasound
- 2013
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Ingår i: International Journal of Enhanced Research in Science Technology & Engineering. - 2319-7463. ; 2:11, s. 130-134
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- If anyone begins to think about the term ultrasound, the first thing that comes to the mind is the fact that it is used in animal communications (e.g., bat navigation and dog whistles). Also, one may start to think that this term is familiar in daily life and has been used many times in medicine applications for foetal imaging, (SONAR). However, many questions come to the mind, such as, what is happening when ultrasound is transmitted through the body? If it is sound, he asks himself why I cannot hear any sound? The interaction between bubbles and sound waves in liquids leads to the phenomenon of acoustic cavitation. The meaning of the word cavitation is not known or understandable for many people. This paper is to contribute the knowledge of bubble power under the action of ultrasound and to give a more comprehensive description of this phenomenon.
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| 3. |
- Alhelfi, Ali Kadhim Hadi, et al.
(författare)
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Design Considerations for Solid Oxide Fuel Cell Auxiliary Power Units for Luxury Passenger Vehicle
- 2013
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Ingår i: The proceeding of 8th International Conference on Multiphase Flow, 2013.
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Konferensbidrag (refereegranskat)abstract
- SOFC systems, working at high temperatures of about 800°C, have recently attracted significant interests for application as automotive and stationary power supply systems. This paper explores the possibilities and limitations for achievement of solid oxide fuel cells (SOFCs) as 7 kW auxiliary power units on luxury passenger vehicles operating on diesel fuel. Various issues are discussed, e.g., the requirements and specifications for the unit as well as the advantages, challenges, and development issues for SOFCs in such applications. System design and analysis are carried out. The calculations are performed for two voltage systems 12/14 V and 36/42 V, respectively. The influences of others parameters like the mass flow rates of air and gases, water production and heat production are also evaluated for the two voltage systems.
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| 4. |
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| 5. |
- Alhelfi, Ali Kadhim Hadi
(författare)
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Heat Transfer in Liquid Film over the Surface of a Rotating Disk Subjected to Impinging Jet
- 2012
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Rapport (populärvet., debatt m.m.)abstract
- This work is theoretical analyses of heat transfer across film a flowing over the surface of a rotating disk. This field has wide industrial applications in Turbomachinery, chemical, and food industries. An analytical study is developed to investigate the heat transfer characteristics in the liquid film due to jet impinging at the center of the disk. A theoretical model is based on heat balance and energy equations developed for a rotating disk heated by a constant heat flux and the free surface are subjected to the surrounding. Local Nusselt number and temperature were found for different selected parameters such as Prandtl number and Reynolds number. Nusselt number obtained from the present model was compared with that obtained by Thomas et al., and the agreement between the results was acceptable.
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| 6. |
- Alhelfi, Ali Kadhim Hadi, et al.
(författare)
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Modeling of Spherical Gas Bubble Oscillation in Acoustic Pressure Field
- 2013
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Ingår i: Proceedings Of The 8th International Conference on Multiphase Flow, 2013.
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Konferensbidrag (refereegranskat)abstract
- Different applications of high power ultrasound in industry and medical applications are based on the propagation and collapse of acoustic cavitation bubbles. This paper presents an enhanced numerical model and simulated results of formation and collapse of a single bubble in a liquid for two cases: bubble with uniform pressure and a bubble with variable pressure inside. For the two cases, both heat transfer inside the bubble and heat transfer to the surrounding liquid are taken into account. Various fundamental properties of oscillating bubbles in ultrasonic acoustic field, such as pressure, temperature and velocity fields inside the bubble under the influence of time-dependent acoustic pressure, have been investigated and the results show that neglecting the pressure gradient inside the bubble affects considerably the bubble dynamics.
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| 7. |
- Alhelfi, Ali Kadhim Hadi, et al.
(författare)
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NUMERICAL INVESTIGATION OF AN OSCILLATING GAS BUBBLE IN AN ULTRASONIC FIELD
- 2014
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Konferensbidrag (refereegranskat)abstract
- The discovery of acoustic cavitation phenomenon is an important role in the design of a wide range of devices handling liquids and it has led to a renewed interest in the bubble dynamics in a sound field.In this study, the nonlinear behaviour of individual gas bubble in liquid under the action of ultrasound fields has been analysed, and simulated results of formation and collapse of a bubble have been provided. The characterization of acoustic cavitation bubbles under theinfluence of periodic pressure field, e.g., the motion of the bubble surface, pressure, temperature and density fields inside the bubble have been investigated and the results are compared with experimental data. The numerically calculated results reveal that the assumption of polytropic approximation inside the bubble predicts that a radius-time curve does not fit to the observed data. Also, the results indicate that the pressure gradient and the heat transfer inside the bubble and across the bubble surface play a major role to predict the extreme conditions associated with the bubble collapse.
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| 8. |
- Alhelfi, Ali Kadhim Hadi
(författare)
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On Bubble Dynamics in Acoustic Cavitation
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nyligen har mycket uppmärksamhet ägnats åt studier rörande ickelinjära oscillationer av sfäriska gasbubblor i pulserande tryckfält. Denna lic-avhandlning syftar till att utöka kunskapen kring kavitationsfenomenet. I detta arbete undersöks olika modeller och en förbättrad numerisk modell har utvecklats för att analysera akustiska kavitationsfenomen. Resultaten från den utvecklade modellen innefattar bildande och kollaps av enstaka gasbubblor i en vätska under inverkan av ultraljud som en funktion av tiden. Modellen valideras och jämförs för tre huvudfall. Dessa fall är: enhetligt tryck och temperatur inne i bubblan, enhetligt tryck och varierande temperatur inne i bubblan, samt varierande tryck och temperatur inne i bubblan. För fall 2 och fall 3 tas hänsyn både till värmeöverföringen inne i bubblan och till den omgivande vätskan. Olika grundläggande egenskaper hos oscillerande bubblor i ett ultraljud akustiskt fält såsom tryck, temperatur, densitet, hastighet och acceleration inne i bubblan under påverkan av tidsberoende ljudtryck har undersökts och resultaten för varje enskilt fall jämförs med motsvarande experimentella data. De numeriskt beräknade resultaten visar att antagandet om ett enhetligt tryck och temperatur inuti bubblan predikterar ett samband mellan radien och tiden som avviker starkt från de uppmätta värdena. Vidare visades det att för att prediktera de extrema tillstånd som förknippas med en kollaps måste bubblans dynamik ta hänsyn både till tryckgradienten och värmeöverföringen inne i bubblan samt över bubblans yta.
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| 9. |
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| 10. |
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| 11. |
- Alhelfi, Ali Kadhim Hadi
(författare)
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Solar Thermal Technology
- 2012
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Rapport (populärvet., debatt m.m.)abstract
- Abstract in Undetermined This project aims to explain the solar thermal technology and support a real technical revolution to help the power industry to become cleaner than before. Also, in this project the technologies and systems developed thus far and their approximate costs will be described.
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| 12. |
- Alhelfi, Ali Kadhim Hadi, et al.
(författare)
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Solid Oxide Fuel Cell Auxiliary Power Units for Heavy Duty Trucks
- 2012
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Ingår i: Proceedings Of The ASME 10th Fuel Cell Science, Engineering, and Technology Conference, 2012. ; , s. 317-325
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Konferensbidrag (refereegranskat)abstract
- This paper explores the potentials of solid oxide fuel cells (SOFCs) as 3 kW auxiliary power units for trucks and military vehicles operating on diesel fuel. Various issues are discussed, e.g., the requirements and specifications for the unit as well as the advantages, challenges, and development issues for SOFCs in such applications. System design and analysis are carried out. The major component of the system is the fuel cell stack. The calculations are performed for two voltage systems 12/14 V and 36/42 V, respectively. The influences of others parameters like the mass flow rates of air and gases, water production and heat production are also evaluated for the two voltage systems.
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| 13. |
- Alhelfi, Ali Kadhim Hadi, et al.
(författare)
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The Cavitation Phenomenon: A Literature Survey
- 2014
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Ingår i: Transactions of the Wessex Institute.
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Konferensbidrag (refereegranskat)abstract
- The meaning of the word cavitation is not known or understandable for many people. The definition which is commonly known about such phenomena is that the formation of cavities or bubbles is encouraged by a pressure change in the surroundings. However, cavitation is much more complex. A large amount of research work and studies on the dynamics of the cavitation phenomenon via numerical investigations or by means of experimental studies have been performed in this sense over past years in order to improve the understanding of the various physical processes involved in this phenomenon. This paper presents a literature survey of existing studies on the cavitation phenomenon and aims to give a comprehensive collection of knowledge about it. The present work does not aim to review all published results in this field. The paper focuses on specific available published results, concerning the most common cavitation types especially acoustic cavitation. The authors like to provide some recommended notices and the main efforts which must be carried out to develop and contribute more efficient knowledge about the real situation and the main results associated with this phenomenon.
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| 14. |
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| 15. |
- Kadhim, Ali, et al.
(författare)
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Evaluation of vehicle tracking for traffic monitoring based on road surface mounted magnetic sensors
- 2013
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Ingår i: The Third IFAC Symposium on Telematics Applications (TA 2013)Applications. - Red Hook, NY : Curran Associates, Inc.. - 9781629937243 ; , s. 13-18
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Konferensbidrag (refereegranskat)abstract
- The aim of this work is to evaluate a vehicle tracking scheme as a means of monitoring traffic on roads. The scheme can be used as a component in a traffic monitoring system which can provide traffic management systems and road maintainers with traffic information. Vehicle tracking is achieved by determining vehicle position, velocity and magnetic moment using a nonlinear weighted least squares method (NWLS) on readings from two 3-axes magnetic sensors.The tracking was performed both in simulation and in real life. The traffic monitoring system is composed of two adjacently glue attached wireless sensor nodes, which are placed at a distance of 1 m along the road. A potential misalignment of the sensors due to placement errors is analysed in simulation and addressed.
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| 16. |
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| 17. |
- Kadhim, Ali, et al.
(författare)
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Relative Gain Array Estimation Based on Non-Parametric Frequency Domain System Identification
- 2014
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Ingår i: 2014 IEEE International Conference on Control Applications (CCA 2014). - Piscataway, NJ : IEEE Communications Society. - 9781467345033 ; , s. 110-115
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Konferensbidrag (refereegranskat)abstract
- Since the introduction of the Relative Gain Array (RGA) by Bristol in 1966, it has received a high level of attention as a practical tool for solving the input-output pairing problem in decentralized control. Moreover, many extensions have been proposed like e.g. for the dynamic case and non-square system matrices. Recently, extensions that provide tools for uncertain parametric process models were suggested. In order to removethe dependency of these tools on a parametric description and accurate knowledge of a nominal model this paper proposes a method to calculate the RGA directly from a non-parametric frequency response matrix (FRM), derived from frequency domain system identification approach. The proposed method reduces the influence of model uncertainties on the calculation of the RGA and derives the RGA at frequencies of interest. Using Monte-Carlo principles, the variance of the estimated RGA is derived and compared with recently proposed methods. The results are exemplified on 2 by 2, 2 by 3 and 3 by 3 systems. It concluded that the proposed methods performs well and robust, while simplifying the estimation of the RGA.
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