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We consider the problem of placing copies of objects in a distributed web server system to minimize the cost of serving read and write requests when the web servers have limited storage capacities. We formulate the problem as a 0–1 optimization problem and present a hybrid particle swarm optimization algorithm to solve it. The proposed hybrid algorithm makes use of the strong global search ability of particle swarm optimization (PSO) and the strong local search ability of tabu search to obtain high quality solutions. The effectiveness of the proposed algorithm is demonstrated by comparing it with the genetic algorithm (GA), simple PSO, tabu search, and random placement algorithm on a variety of test cases. The simulation results indicate that the proposed hybrid approach outperforms the GA, simple PSO, and tabu search. 相似文献
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This study examined the use of electronic resources among academic scholars of The Islamia University of Bahawalpur (IUB), Punjab, Pakistan. A quantitative survey was found most convenient and useful for this study. The total population of the study was 169 research students in IUB. The response rate was 79% and 133 utilizable responses were coded and analyzed by using SPSS software. Results of the study showed that most of the researchers (61%) used electronic resources daily for many purposes and reasons. Most of them (57%) were “satisfied” with the usage of electronic resources. Learning, education, and research were the main purposes, and easy use and easy access to documents were the major reasons of using these resources. Lack of internet connection is the major problem faced by the respondents. 相似文献
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The game of hurling is ranked as one of the fastest and most skilful field games in the world. It is played by a stick, hurley, made of ash wood and a ball, sliotar, made of a cork core or similar viscoelastic materials. Better standardisation of the game equipment requires analysing impacts to quantify precisely the effect of variations in equipment design on the resultant impact force at low and high striking speeds. Therefore, the purpose of the present study was to use a high-speed camera to (1) characterise the impact dynamics in term of impact force magnitude and duration, and (2) investigate whether a relationship exists between the game equipment and the magnitude of the impact force. An air cannon unit (ACU) test rig was set up to cause the sliotar to strike the hurley at predetermined speeds. A high-speed camera operating at 12,500 frames per second (fps) was used to capture 32 experimental impacts covering a range of sliotar and hurley brands, impact locations and impact speeds. The factor ??sliotar brand?? was identified as the most significant factor for the impact force among other main factors and two-factor interactions at a constant speed and it had a significant effect with up to 27?% difference between sliotar brands. It was demonstrated that, at higher impact speeds, the force?Cdeformation curves of the sliotar brands varied significantly, even though similar force?Cdeformation curves have been reported at quasi-static compression and similar COR values at low impact speeds using the standard free-drop test. This is the first known study to characterise the unique, highly non-linear and anisotropic sliotar?Churley impact using high-speed camera technology. It highlights the need for a tighter standard for sliotar materials and manufacturing to increase uniformity between different brands and strongly suggests that the standard free-drop test is not sufficient to characterise and compare game equipment. 相似文献
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Ahmad Mohammad Qablan Amjad Abuloum Jamal Abu Al-Ruz 《Journal of Science Education and Technology》2009,18(3):291-300
A series of interviews and classroom observations were conducted with a group of in-service science teachers, students, school
principal, and computer lab supervisors, from a “Discovery” female school in Jordan to assess their utilization of information
and communication technology (ICT) in teaching science. The study also intended to determine how these participants were using
ICT and if they had any internal and external impediments in the way of the effective integration of ICT in the teaching of
science. Results showed that some participants were using ICT creatively in their science teaching. However, despite considerable
political pressure to increase ICT use in the classroom, most expressed frustration at the lack of ICT tools, support from
the school, from the Ministry of Education, and from the surrounding community. The article proposes possible resolutions
to help these participants overcome their impediments. Some of the suggested resolutions for the internal impediments include
involving teachers in preparing the school’s time-table, equipping the school with more ICT tools and offering more training
courses for teachers. However, the suggested resolutions for the external impediments involve (1) The Ministry of Education
to rethink the administration of board examinations, (2) The school to sacrifice scoring higher in board examinations for
preparing more creative and more versatile students’ perspectives. 相似文献
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Recent Western Reflections on Islamic Education 总被引:1,自引:0,他引:1
Amjad Hussain 《Religious education (Chicago, Ill.)》2013,108(5):579-585
This book review will examine and evaluate a number of books with regards to Muslim Education in the contemporary Western world. It will look at how the various books highlight and deal with (1) the growing awareness of the impact of Islamic education as an integral part of a young European Muslim's identity and its affect on the local and the larger community and (2) the necessity to try to engage with a new definition of Islamic education and its practice outside the traditional Muslim world. 相似文献
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A.V. Balakrishnan Amjad M. Tuffaha Iylene Patino Oleg Melnikov 《Journal of The Franklin Institute》2014
We present a methodology for calculating flutter speeds of a high aspect ratio flying wing articulated with point masses in inviscid air flow. This highly flexible wing configuration typically models a HALE (High Altitude Long Endurance) UAV (Unmanned Aerial Vehicle) type aircraft. To demonstrate the procedure, we perform flutter analysis on an actual articulated wing model and we investigate the dependence of the flutter speed on the number of loads mounted onto the structure and the number of panels comprising the flying wing for both varying and constant span. The results show that the flutter speed decreases as more panels and point masses are incorporated into the flying wing. On the other hand, the number of point masses mounted onto the structure has a small effect on the flutter speed if the wing span is kept constant. 相似文献
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