Rotary inverted pendulum with magnetically external perturbations as a source of the pendulum’s base navigation commands     

Gisela Pujol-Vazquez  Leonardo Acho  Saleh Mobayen  Amelia Nápoles  Vega Pérez 《Journal of The Franklin Institute》2018,355(10):4077-4096

The main objective of this paper is to drive a rotary inverted pendulum by following a desired navigation instruction. This navigation is commanded by the user through a new electromagnetic device which is allowed to perturb the pendulum from its upright position. This apparatus consists of an electronic magnetic driving circuit to introduce commands and realized via two operated magnetic coils. So, the external programmed magnetic perturbation can be seen as external commandments. Therefore, the control problem statement is solved via a modified regulation control implementation, to maintain the pendulum on its upright position and giving free manipulation of the base of the rotary inverted pendulum. Hence, by using the corresponding H_∞-linear matrix inequality technique, a static state controller is designed and tested experimentally so supporting our findings.  相似文献   

Using cloud computing services in e-learning process: Benefits and challenges     

Abderrahim El Mhouti  Mohamed Erradi  Azeddine Nasseh 《Education and Information Technologies》2018,23(2):893-909

During the recent years, Information and Communication Technologies (ICT) play a significant role in the field of education and e-learning has become a very popular trend of the education technology. However, with the huge growth of the number of users, data and educational resources generated, e-learning systems have become more and more expansive in terms of hardware and software resources, and many educational institutions cannot afford such ICT investments. Due to its tremendous advantages, cloud computing technology rises swiftly as a natural platform to provide support to e-learning systems. This paper focuses on the research on the application of cloud computing in e-learning. The aim of this paper is to give an overview of the current state and the impact of the use of cloud computing for e-learning. Thus, at first the paper introduces concepts of e-learning and cloud computing infrastructure with their key characteristics. The paper analyzes also challenges facing e-learning systems deployment. In follow the paper considers cloud-based e-learning solutions by focusing on the raisons of the convenience of cloud computing for e-learning. Therefore cloud computing benefits are introduced as a solution for these challenges. Finally, the paper presents some solutions of cloud computing in e-learning and describes the most common architecture adopted. Issues in implementing cloud-based e-learning systems and some potential ways to overcome them are also discussed.  相似文献   

Replicating web contents using a hybrid particle swarm optimization     

Amjad Mahmood 《Information processing & management》2010

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   

Between the public intellectual and the scholar: decolonization and some post-independence initiatives in African higher education     

Mahmood Mamdani 《Inter-Asia Cultural Studies》2016,17(1):68-83

This article focuses on epistemological decolonization, including knowledge production and its institutional locus – the university – in the post-independence African context. The article begins by problematizing both the concept and the institutional history of the university, in its European and African contexts, to underline the specifically modern character of the university as we know it and its genesis in post-Renaissance Europe. Against this background, the article traces post-independence reform of universities in Africa, which is unfolding in two waves: the first on access, Africanization, generating a debate between rights and justice; and the second on institutional reform, epitomized by the debate around disciplinarity. At the same time, the notions of excellence and relevance have functioned as code words, each signaling a different trajectory in the historical development of the university. Lastly, the article explores the role and tension between the public intellectual and the scholar from the perspective of decolonization.  相似文献   

Efficacy of a Preventive Counseling Program for Improving Psychological Hardiness and the Positive Use of Social Network Sites among Students at Risk     

Abdallah Salem Farhan Almahaireh  Anas Saleh Rabi Aldalaeen  Suhib Khaled Ahmad Takhaineh 《International journal for the advancement of counseling》2018,40(2):173-186

The purpose of this study was to investigate the efficacy of a preventive counseling program for improving psychological hardiness (PsyH) and the positive use of social network sites (SNSs). The sample consisted of 30 students from Mu’tah University in Jordan who were randomly assigned into either an experimental group (15) or a control group (15). Two constructed scales - the PsyH scale and the Positive Use of SNSs scale - were administered to both groups pre-test and post-test, and a one-month follow-up measure was also administered to the experimental group. The findings revealed that the preventive counseling program significantly improved the level of PsyH and the positive use of SNSs and seemed to have sustained efficacy.  相似文献   

Effects of loading rate and hydraulic residence time on anoxic sulfide biooxidation   总被引：1，自引：0，他引：1  

CAI Jing ZHENG Ping MAHMOOD Qaisar ISLAM Ejazul HU Bao-lan WU Dong-lei 《浙江大学学报(A卷英文版)》2007,8(7):1149-1156

The optimal operation conditions in an anoxic sulfide oxidizing (ASO) bioreactor were investigated. The maximal removal rates for sulfide and nitrate were found to be 4.18 kg/(m3·d) and 1.73 kg/(m3·d), respectively. The volumetrical volumetric loading rates (LRs) observed through decreasing hydraulic retention time (HRT) at fixed substrate concentration are higher than those by increasing substrate concentration at fixed HRT. The sulfide oxidation in ASO reactor was partially producing both sulfate and sulfur; but the amount of sulfate produced was approximately one third that of sulfur. The process was able to tolerate high sulfide concentration, as the sulfide removal percentage always remained near 99% when influent concentration was up to 580 mg/L. It tolerated relatively lower nitrate concentration because the removal percentage dropped to 85% when influent con- centration was increased above 110 mg/L. The process can tolerate shorter HRT but careful operation is needed. Nitrate conversion was more sensitive to HRT than sulfide conversion since the process performance deteriorated abruptly when HRT was decreased from 3.12 h to 2.88 h. In order to avoid nitrite accumulation in the reactor, the influent sulfide and nitrate concentrations should be kept at 280 mg/L and 67.5 mg/L respectively. Present biotechnology is useful for removing sulfides from sewers and crude oil.  相似文献   

No scholar is an island: The impact of sharing in the work life of scholars          下载免费PDF全文

Carol Tenopir  Suzie Allard  Lisa Christian  Robert Anderson  Suzan Ali‐Saleh  Dave Nicholas  Anthony Watkinson  Hazel Woodward 《Learned Publishing》2017,30(1):5-17

The sharing of scholarly articles is an intrinsic and often ignored facet of the value and mission of scholarship. It is so entwined in the daily work life of scholars that it has almost become second nature, an integral part of the research process itself. This article addresses this often overlooked area of research in usage studies. In an international survey of 1,000 published scholars, the Beyond Downloads project examined their sharing behaviours in order to gain a more contextualized and accurate picture of their usage beyond download patterns and citation counts. Scholars share published articles with others as a mode of content discovery and dissemination, particularly if they work in groups, and most expect to increase their sharing in the future. While their methods of sharing articles may change, and their reasons for sharing may vary from self‐promotion to the more altruistic motives of scientific progress, they desire to share the final published versions of articles with their colleagues.  相似文献   

Interaction between seed size and NaCl on germination and early seedling growth of some Turkish cultivars of chickpea （Cicer arietinum L.）     

Kaya M  Kaya G  Kaya MD  Atak M  Saglam S  Khawar KM  Ciftci CY 《Journal of Zhejiang University. Science. B》2008,9(5):371-377

Chickpea is an important food legume crop of Turkey and is largely grown for human consumption on low moisture or salt-affected soils.The objective of the study was to find the effects of NaCl stress at electrical conductivities of 4.5,8.6,12.7 and 16.3 dS/m and seed sizes (7,8 and 9 mm) on germination and early seedling growth of three popular chickpea cultivars (AKN-97,Gokce and Uzunlu-99).Mean frequency of germination,germination time,germination index,root length,shoot length and seedling fresh weight showed seed size-dependent responses of cultivars to salt stress.In general,small seeds germinated and grew more rapidly compared to medium and large seeds of the same cultivars against all levels of salt stress,with the best results in cultivar Uzunlu-99.No effect of NaCl treatments was observed on frequency of germination; however,a drastic decrease in early seedling growth was recorded at increased NaCl concentrations.Regression analysis results showed a significantly positive rela-tionship (P<0.01) between seed size and mean germination time,whereas a significantly negative relationship was recorded between seed size and germination index,root length,shoot length.Moreover,linear regression values apparently confirmed that increased seed size in each cultivar affected decreased germination index,root and shoot lengths with enhanced mean germination time.Thus,it was concluded that the use of small seeds could considerably reduce the production costs of chickpea in salt-affected soils.  相似文献   

An exact analytical solution for convective heat transfer in rectangular ducts     

Mohammad Mohsen Shahmardan  Mahmood Norouzi  Mohammad Hassan Kayhani  Amin Amiri Delouei 《浙江大学学报(A卷英文版)》2012,13(10):768-781

An exact analytical solution is obtained for convective heat transfer in straight ducts with rectangular cross-sections for the first time. This solution is valid for both H1 and H2 boundary conditions, which are related to fully developed convective heat transfer under constant heat flux at the duct walls. The separation of variables method and various other mathematical techniques are used to find the closed form of the temperature distribution. The local and mean Nusselt numbers are also obtained as functions of the aspect ratio. A new physical constraint is presented to solve the Neumann problem in non-dimensional analysis for the H2 boundary conditions. This is one of the major innovations of the current study. The analytical results indicate a singularity occurs at a critical aspect ratio of 2.4912 when calculating the local and mean Nusselt numbers.  相似文献   

Electronic resources and services in Pakistani university libraries: A survey of users' satisfaction     

Muhammad Sajid Mirza  Khalid Mahmood 《International Information and Library Review》2012,44(3):123-131

This study is an attempt to evaluate the effectiveness of electronic resources and services in Pakistani university libraries on the basis of users' satisfaction. A survey method was employed to conduct the research. Using convenience sampling, eight university libraries; four each from Islamabad and Lahore including two from the public sector and two from the private sector having IT applications, were included in the users survey. The total population (i.e., 40,236) of library users was very large; therefore, a reasonable, manageable and convenient sample of 800 library users, including 100 users each from the eight libraries was selected. A semi structured questionnaire was designed to collect data, while a five-point Likert Scale from 1 (Dissatisfied) to 5 (Extremely satisfied) was used to measure the satisfaction level of the respondent. The study concluded that Pakistani university libraries are offering effective electronic resources and services to their users.  相似文献