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1.
Hamed Jabbari Asl Tatsuo Narikiyo Michihiro Kawanishi 《Journal of The Franklin Institute》2019,356(13):7144-7163
In this study, we addressed the problem of design of high-performance tracking controller for uncertain systems described by the Euler–Lagrange formulation. The main objective was to combine the advantages of the robust integral of the sign of the error (RISE) controller with those of the prescribed performance (PP) controller. In particular, we aimed to obtain asymptotic tracking for the uncertain systems through a continuous control command while ensuring the transient performance. Two controllers were developed. First, the PP property was injected into the RISE controller assuming no constraint on the actuation amplitude existed, and then this property was incorporated into the saturated RISE controller. The performance of the proposed controllers was validated through experimental and simulation tests. 相似文献
2.
This paper proposes a pursuit formation control scheme for a network of double-integrator mobile agents based on a vector field approach. In a leaderless architecture, each agent pursues another one via a cyclic topology to achieve a regular polygon formation. On the other hand, the agents are exposed to a rotational vector field such that they rotate around the vector field centroid, while they keep the regular polygon formation. The main problem of existing approaches in the literature for cyclic pursuit of double-integrator multiagent systems is that under those approaches, the swarm angular velocity and centroid are not controllable based on missions and agents capabilities. However, by employing the proposed vector field approach in this paper, while keeping a regular polygon formation, the swarm angular velocity and centroid can be determined arbitrary. The obtained results can be extended to achieve elliptical formations with cyclic pursuit as well. Simulation results for a team of eight mobile agents verify the accuracy of the proposed control scheme. 相似文献
3.
Ali Karami-Mollaee Hamed Tirandaz Oscar Barambones 《Journal of The Franklin Institute》2019,356(8):4577-4600
Mismatched uncertainty and chattering appear as two challenges in sliding mode control. To overcome the problem of mismatched uncertainty, multiple sliding surfaces with virtual inputs are proposed. Accordingly, we have proposed two new methods based on designed neural observer: sliding mode control (SMC) and dynamic sliding mode control (DSMC) methods. Although, the proposed SMC can significantly cope with the mismatched uncertainties, but it suffers from chattering phenomenon. The chattering problem can be removed in DSMC, because an integrator is placed before the system. This results in increased number of the system states. This new state can be identified with the proposed neural observer. Note that in both proposed approaches, the robust performance (invariance property) of system is reserved, even in the presence of mismatch uncertainties. Then, to have a valid comparison the proposed DSMC is also designed using loop transfer recovery observer (LTRO). This comparison shows the good performance of the DSMC based neural networks. Moreover, the upper bound of uncertainties is not used in SMC and DSMC controllers and also in the neural observer and LTRO, which is important in practical implementation. Finally, comparing the equations, one can see the simplicity of DSMC in concept and also in realization. 相似文献
4.
Internet evolution has affected all industrial, commercial, and especially learning activities in the new context of e-learning. Due to cost, time, or flexibility e-learning has been adopted by participators as an alternative training method. By development of computer-based devices and new methods of teaching, e-learning has emerged. The effectiveness of such programs is dependent on powerful learning management systems. In this paper, a neuro-fuzzy approach is proposed based on an evolutionary technique to obtain an optimal learning path for both instructor and learner. The neuro-fuzzy synergy allows the diagnostic model to imitate instructor in diagnosing learners’ characteristics, and equips the intelligent learning environment with reasoning capabilities. These reasoning capabilities can be used to drive pedagogical decisions based on the learning style of the learner. The neuro-fuzzy implementation helps to encode both structured and non-structured knowledge for the instructor. On the other hand, for learners, the neural network approach has been applied to make personalized curriculum profile based on individual learner requirements in a fuzzy environment. 相似文献
5.
Shaymaa M. M. Yahya Shadia A. Fathy Zakaria A. El-Khayat Safinaz E. El-Toukhy Ahmed R. Hamed Marwa G. A. Hegazy Heba K. Nabih 《Indian journal of clinical biochemistry : IJCB》2018,33(1):21-30
Hepatocellular carcinoma (HCC) is a hypervascular primary liver cancer characterized by rapid progression, besides, resistance to traditional chemotherapeutic agents. It has been shown that microRNAs play critical roles in regulation of tumor cell sensitivity to drugs through modulating the expression of genes involved in drug transport. The present study investigated whether restoration of miR-122 in HCC cells could alter the cell cycle distribution and the expression of multidrug resistance (MDR)-related genes (ABCB1, ABCC1, ABCG2 and ABCF2). After overexpression of miR-122 in HepG2 cells treated or untreated with doxorubicin doses, total RNAs and protein extracts were isolated for application of QRT-PCR and western blotting techniques. Moreover, cell cycle distribution was monitored by flow cytometry. Our results revealed that, the over expression of miR-122 in HepG2 cells treated or untreated with doxorubicin could modulate the sensitivity of cells to chemotherapeutic drug through downregulation of MDR-related genes, ABCB1 and ABCF2. Interpretation of cell cycle distribution revealed that, the anti-proliferative effect of miR-122 is associated with the accumulation of cells in G0/G1 phase. Moreover, treatment with miR-122 and doxorubicin resulted in high percentage of HCC cells in G0/G1 phase. Taken together, our findings revealed that, overexpression of miR-122 inhibited HCC cell growth by inducing cell cycle arrest and this arrest is associated with down-regulation of MDR-related genes. 相似文献
6.
Creating scientific dialogue through social media: exploration of Saudi pre-service science teachers
Amani K. H. Alghamdi Fayadh Hamed Alanazi 《Research in Science & Technological Education》2013,31(4):471-491
Background: This study explored how Saudi Arabian pre-service science teachers’ (PST) use of social media (SM) creates scientific dialogue.Design and method: Data were collected via (a) in-depth interviews with eight science PSTs completing their practice teaching during a field experience course (2017 academic year at a Saudi Arabia Eastern province university), (b) focus groups with 21 female science students being taught by the PSTs, and (c) an analysis of SM artifacts (i.e. PST’s students’ Tweets and Snapchat comments about their SM-based science homework).Results: Findings from content analyses indicate that the PSTs overwhelmingly perceived SM-based science teaching as providing their students with opportunities to pose critical questions, improve science learning, and engage in scientific dialogue and argumentation. Students welcomed the SM-based science learning, saying it excited them, made them want to learn science and helped with collaborative science learning. The majority (87%) of PST’s students expressed an interest in using SM to engage with science concepts. Also, findings affirmed that social media serve as mediating agents for reaching students in their learning Zone of Proximal Development; that is, SM-scaffolded science learning. The findings are considered in terms of further pre-service science teacher education and Saudi-based educational research. 相似文献
7.
This empirical research was conducted to investigate the role of transformational leadership, organizational culture and organizational learning in improving the performance of Iranian agricultural faculties and leading them to become learning organizations. The research population consisted of all faculty members of public agricultural faculties affiliated with Iran’s Ministry of Science, Research and Technology. A sample of 329 faculty members was selected using stratified random sampling method with proportional allocation. Questionnaire was the main tool for data gathering. Validity of the questionnaire was verified using average variance extracted. Composite reliability coefficients were calculated for determining the reliability of the questionnaire. Collected data were analyzed by structural equation modeling technique using Lisrel 8.50 software package. The results showed that there was a positive and significant relation between contextual components (transformational leadership and learning organizational culture) and process component (organizational learning). These two contextual components could explain 87.3 % of the process component variance. Also, there was a positive and significant relation between process component and performance component, and the process component could explain 36 % of the performance component variance. Our findings support that transformational leadership and learning organizational culture with the effect on organizational learning process not only improve the agricultural faculty performance, but also change them to learning organizations. 相似文献
8.
The rapid growth of the Web has increased the difficulty of finding the information that can address the users’ information needs. A number of recommendation approaches have been developed to tackle this problem. The increase in the number of data providers has necessitated the development of multi-publisher recommender systems; systems that include more than one item/data provider. In such environments, preserving the privacy of both publishers and subscribers is a key and challenging point. In this paper, we propose a multi-publisher framework for recommender systems based on a client–server architecture, which preserves the privacy of both data providers and subscribers. We develop our framework as a content-based filtering system using the statistical language modeling framework. We also introduce AUTO, a simple yet effective threshold optimization algorithm, to find a dissemination threshold for making acceptance and rejection decisions for new published documents. We further propose a language model sketching technique to reduce the network traffic between servers and clients in the proposed framework. Extensive experiments using the TREC-9 Filtering Track and the CLEF 2008-09 INFILE Track collections indicate the effectiveness of the proposed models in both single- and multi-publisher settings. 相似文献
9.
Ivan K. Farrell Kastro M. Hamed 《Journal of Research on Technology in Education》2017,49(3-4):161-181
Utilizing a correlational research design, we sought to examine the relationship between the technological pedagogical content knowledge (TPACK) of in-service teachers and student achievement measured with each individual teacher's Value-Added Model (VAM) score. The TPACK survey results and a teacher's VAM score were also examined, separately, with respect to teacher attributes. Upon examination of VAM scores and teacher attributes, the subject area, the percentage of economically disadvantaged students at the teacher's school, and the grade level of the teacher were all significantly related to VAM scores. In addition, the TPACK survey results overall and its constructs were examined with teacher attributes. The significant relationships were gender, subject area, the number of certifications, highest degree held by the teacher, years teaching, and teaching in/out of area. The analysis showed no significant relationship between a teacher's VAM score and the TPACK survey overall or its individual constructs. 相似文献
10.
Studies of social networks highlight the importance of network structure or structural properties of a given network and its impact on performance outcome. One of the important properties of this network structure is referred to as social capital, which is the network of contacts and the associated values attached to these networks of contacts. This study provides empirical evidence of the influence of social capital and performance within the context of academic collaboration (coauthorship) and suggests that the collaborative process involves social capital embedded within relationships and network structures among direct coauthors. Association between scholars' social capital and their citation-based performance measures is examined. To overcome the limitations of traditional social network metrics for measuring the influence of scholars' social capital within coauthorship networks, the traditional social network metrics is extended by proposing two new measures, of which one is non-weighted (the power–diversity index) and the other (power–tie–diversity index) is weighted by the number of collaboration instances. The Spearman's correlation rank test is used to examine the association between scholars' social capital measures and their citation-based performance. Results suggest that research performance of authors is positively correlated with their social capital measures. The power–diversity index and power–tie–diversity index serve as indicators of power and influence of an individual's ability to control communication and information. 相似文献