2,449 research outputs found

    Optimal tuning linear quadratic regulator for gas turbine by genetic algorithm using integral time absolute error

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    For multiple input-multiple output (MIMO) systems, the most common control strategy is the linear quadratic regulator (LQR) which relies on state vector feedback. Despite this strategy gives very good result, it still has trial and error procedure to select the values of its weight matrices which plays a important role in reaching to the desiered system performance. In order to overcome this problem, the Genetic algorithm is used. The design of genetic algorithm based linear quadratic regulator (GA-LQR) utilized Integral time absolute error (ITAE) as a cost function for optimization. The propsed procedure is implemented on a linear model of gas turbine to control the generator spool’s speed and the output power

    Performance study of an underlay cognitive radio network in the presence of co-channel interference

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    PhD ThesisMassive innovation in all aspects of the wireless communication network has been witnessed over the last few decades. The demand for data throughput is continuously growing, as such, the current regulations for allocating frequency spectrum are not able to respond to this exponential growth. Cognitive radio (CR), has been proposed as a solution to this problem. One of the possible scenarios of the implementation of CR is underlay cognitive radio. In this thesis the performance of an underlay cognitive radio network (UCRN) in the presence of the co-channel interference (CCI) is assessed. Firstly, the impact of CCI on the dual-hop cooperative UCRN is investigated over Rayleigh fading channels. In order to do this, the exact outage probability (OP), average error probability (AEP) and the ergodic capacity (EC) are studied. In addition, simple and asymptotic expressions for the OP and AEP are derived. Furthermore, the optimal power allocation is investigated to enhance the network performance. Moreover, the performance of a multi-user scenario is studied by considering the opportunistic SNR-based selection technique. Secondly, the effect of both primary network interference and CCI on the dual-hop UCRN over Rayleigh fading channels are studied. The equivalent signal-to-interference-plus-noise ratio (SINR) for this network scenario is obtained by considering multi-antenna schemes at all receiver nodes. The different signal combinations at the receiver nodes are investigated and compared, such as selection combining (SC) and maximum ratio combining (MRC) techniques. Then, the equivalent probability density function (PDF) and cumulative distribution function (CDF) of the network’s equivalent SINR are derived and discussed. Furthermore, expressions for the exact OP, AEP, and EC are derived and reviewed. In addition, asymptotic OP expressions are obtained for different case scenarios to gain an insight into the network parameters. Thirdly, multiple-input multiple-output (MIMO) UCRN is investigated under the influence of primary transmitter interference and CCI over Rayleigh fading channels. The transmit antenna selection and maximum ratio combining (TAS/MRC) techniques are considered for examining the performance of the secondary network. At first the equivalent SINR for the system is derived, then the exact and approximate expressions for the OP are derived and discussed. Fourthly, considering Nakagami-m fading channels, the performance of the UCRN is thoroughly studied with the consideration of the impact of primary network interference and CCI. The equivalent SINR for the secondary system is derived. Then, the system equivalent PDF and CDF are derived and discussed. Furthermore, the OP and AEP performances are investigated. Finally, for the cases mentioned above, numerical examples in conjunction with MatLab Monte Carlo simulations are provided to validate the derived results. The results show that CCI is one of the factors that severely reduces the UCRN performance. This can be more observable when the CCI power increases linearly with the transmission power of the secondary transmitter nodes. Furthermore, it was found that in a multi-user scenario the opportunistic SNR-based selection technique consideration can improve the performance of the network. Moreover, adaptive power allocation is found to give better results than equal power allocation. In addition, cooperative communication can be considered to be an effective way to combat the impact of transmission power limitation of the secondary network and interference power constraint. The multi-antenna schemes are another important consideration for enhancing the overall performance. In fact, despite the interference from the CCI and primary user sources, the multi-antennas scheme does not lose its advantage in the UCRN performance improvementHigher Committee for Education Development in Iraq (HCED). I am also grateful to the Ministry of Transportation and Communication, Kurdistan Regional Government-Iraq

    Fallujah in the Writings of Foreign Travelers in the Ottoman Era

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    Writings of foreign travelers have a prominent place in the modern history of Fallujah, their views cannot be found in other sources. These writings have tackled economic, social, cultural and archaeological themes. However, one must be cautious in dealing with the information derived from such writings. This research paper investigates the writings of travelers to Fallujah from the second half of the 16th century to the beginning of the 20th century. The journeys of these travelers were motivated by factors relating to geographic exploration, economic interests, scientific field studies, and intelligence activities. In search of a trade route to the east of Asia and India, Western colonial governments started exploring routes through the Cape of Good Hope and the Euphrates. Fallujah was the final destination along the Euphrates route, and many travelers journeyed there, and their writings contain descriptions of important stopping places along the river, the charming nature along the landscape, as well as the risks and difficulties of navigation. Travelers also recorded their views and observations of Fallujah’s houses, local economy, and the role of its port as a final travel destination en route Baghdad. The study offers new insights concerning some of the most prominent travelers who passed through Fallujah, including Cesar Frederick, Leonhardt Rauwolff, and Ralph Fitch. The information provided by these travelers can serve as a basis for a hypothesis suggesting that Fallujah was not established in the late 19th century, as some modern scholars argue but was actually re-discovered during this period, having already thrived for several centuries. Keywords: Foreign Travelers; Iraq; Ottoman Era; Euphrates; Fallujah

    The Impact of Supply Chain Management Approaches on Supply Chain Performance in Iraq

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    Indeed due to globalization and changing regional powers, supply chain (SC) has become an essential element. It is evident that political, social and economic changes over the few past decades become supply chain more uncertain and complex. The economy of Iraq is dominated by Oil that is contributing 95% in its foreign exchange. Meanwhile, War has destroyed its major infrastructure still supply is moving on but with more uncertainty. AlthoughWar destroyed the economy badly. However, there are numerous ways to reduce the uncertainty that will improve the performance; supply chain management (SCM) approaches cannot be neglected. Whereas, supply chain management approaches have determined the performance in various industries and in various regions. The aim of this study to explore the potential benefits of supply chain management approaches toward attaining supply chain performance. This is an empirical investigation conducting among members of oil and gas supply chain in Iraq. Data were collected from 260 members of thesupply chain that include drilling, processing, distribution areas of Iraq. Factor analysis and multiple regressions through SPSS have been used for data analysis. The finding of this study reveals that all three supply chain management approaches information sharing (IS), joint decision making (JDM) and risk and reward sharing (RRS) positively and significantly affect the supply chain performance

    Impact of English Orthography on Learning English Sounds and Spelling

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    In order to learn or study English as a foreign language, the learner must be aware of pronunciation skills besides other skills which are of great importance for studying it. In Sudan, there is a large number of people who are interested in learning English as a foreign language. Among them are the students of English language at the University of Gezira. Many studies have demonstrated that the errors made by the speakers of other language who speak English, are systematic rather than random. For instance, scholars and linguists demonstrated that Arab learners of English face problems in pronunciation of sound which they are not familiar with. The present study is limited to the University of Gezira, Faculty of Education – Hassahisa English Department, students during the academic year 2015-2016 and the teachers who teach at University of Gezira-Faculty of Education Hantoub-English Department. The researcher followed the analytical descriptive method to carry out the study. The tools used by the researcher were i) a test for students of 3rd Semester at the University of Gezira, Faculty of Education, Hassahiesa ii) a questionnaire for teachers at University of Gezira, Faculty of Education-Hantoub. Correct pronunciation and spelling have been always a great challenge for the EFL learners. The present research is at attempt to find that how English orthography affects the learning of English sounds and spelling. Moreover, the research may benefit syllabus designers as well as English students who are specialized in the field of English Language by providing lights and hints in the scope of how to write in correct spelling. Keywords: orthography, pronunciation, EFL, University of Gezira, descriptive metho

    Teaching creative thinking skills and its challenges, strategies and future implications: a narrative of IIUM experience

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    This paper aims at exploring, discussing and analyzing some major issues in teaching creative thinking skills (CTS) based on IIUM experience.1 These issues are challenges encountering trainers and lectures in teaching (CTS), strategies to overcome these challenges, and future implications proposed to enhance the process. It is well recognized worldwide that Edward de Bono is a pioneer in designing tools for teaching creative thinking skills since late sixties last century. Therefore, his tools were adopted and incorporated in the syllabus. Tools include six thinking hats, CoRT lessons, and lateral thinking. As such the discussion will be mainly related to those tools. Descriptive, analytical and critical approaches will be used, based on the author’s experience in classroom teaching and training CTS settings that were conducted at IIUM for the last ten years. To put this experience in an academic setting, the views of those who wrote on the subject will be sought. Hopefully this study will lead to enhance the performance of the lectures who teach the subject at IIUM; it will also help both internal and external auditors to improve teaching the subject, and other experts in Muslim world will be able to give feedback on the experience

    The impact of supply chain collaboration on performance in automotive industry: Empirical evidence

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    Purpose: Indeed due to global advancement, rapid technological innovation, and enhancing regional influence, supply chain (SC) has become an essential element. Now, competition has shifted from organization to industry level; any disruption can not only disturb organization but also affect the whole industry. Although Pakistan is agriculture land still industry sector is supporting more than half population, especially the automotive sector is the highest growing sector. Due to regional and economic shift toward China and India, this sector is facing numerous problems. Only thirteen large-scale automotive organizations are operational by creating collaboration among them many issues can be resolved. Supply chain collaboration has dogged the performance in various industries and in various regions. The aim of this study is to explore the potential benefits of supply chain collaboration toward achieving operational performance. Design/methodology/approach: This is an empirical investigation conducting among supply chain department of automotive industries in Pakistan. Data were collected from 232 members of the supply chain that include suppliers, manufacturers, and distributors. Factor analysis and multiple regressions through SPSS have been used for data analysis. Findings: The finding of this study reveals that two supply chain management approaches information sharing (IS), joint decision making (JDM) significantly effect, while Electronic Data Interchange (EDI) does not have a significant effect on operational performance. Research limitations: This study consists only three approaches, next study should include more approaches. Secondly, this study is limited to the automotive sector. Practical implications: [This study will help the managers of the automotive industry in making their operation smooth by applying information sharing, joint decision making, and electronic data interchange. Originality/value: First novelty of this study is the implementation of supply chain collaboration for developing country especially for Pakistan. Secondly, this study seed collaboration as communication and include all aspects of communication like formal communication, informal communication.Peer Reviewe

    ‘Thinking’ terminologies from Qurónic perspective and their impact on human intellectual development

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    The 'Qur'En' as a divine book has terms that are used and related to 'thinking' such as TaIawwur (conceiving), Idrak (perceiving), Fiqh (grasping), TaNaqqul (reasoning), Tadhakkur (contemplating) etc. This paper explores major Qur'Enic terms related to thinking with the aim of uncovering potential value of these terms for human life. For this purpose, both textual and contextual analyses have been applied, as appropriate. The paper argues that internalising the Qur'Enic terms for thinking will contribute to the uplift of the global struggle on formalisation of thinking in public and private places for rightful human thought. The positive influence of Qur'Enic thinking will not remain limited to individuals, but will also affect communities through influence of human thought and behaviour which, in turn, will lead to a paradigm shift in the academic realm
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