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The problem of the realization of integral sliding mode controllers, based only on output information, is applied to a Stewart platform. This platform has three degrees of freedom and it is used as a remote surveillance devise. We consider the hierarchical sliding mode observer, allowing the reconstruction of the system states from the initial moment if we suppose that there exist ideal sliding modes and equivalent output injections. This allows the implementation of an output integral sliding mode controller ensuring the insensitivity of the state trajectory with respect to the matched uncertainties from the initial moment. The discrete realization output integral sliding mode controller requires the filtration to obtain the equivalent output injections. It is shown that the observation error can be made arbitrarily small after an arbitrary small time without any adjustment of the observer parameters, only by decreasing the sampling step and filter time constant. The results obtained are illustrated by simulations. 相似文献
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This article is presented as an interim report on an inquiry which is being conducted at the German Institute for International Educational Research at Frankfurt/Main. The authors being by outlining the organisational structure of special school teacher training at the Faculties of Defectology which have been established at a good number of Colleges of Education. However, the emphasis is laid on identifying current curricular innovations with special regard to the experiments at the Lenin College of Education in Moscow. In the following section specific attention is paid to the function of correspondence studies in the initial and in‐service training of special school teachers. The article is concluded by some remarks about the social status that teachers enjoy in the Soviet Union and by some basic comparison with trends in special teacher education in both Germanies. 相似文献
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This article presents the development and application of group feedback videos (GFVs) in design education. A case study shows how visually‐rich GFVs were developed in a practice‐based design studio subject where learners were required to work in teams and independently calibrate an ability to form judgements on the qualities of their own work. Breaking away from traditional models of individual written feedback, students were instead provided with holistic reviews of project outcomes in a GFV format. Assessment examples were presented from across the cohort with the goal of encouraging open discussion and self‐reflection on studio practice. GFVs supported learning processes through three key characteristics: information richness, group learning and sharing, and formative engagement. What differentiated this approach from previous studies was the focus on audio‐visual group delivery to enhance feedback's richness. By replicating an in‐class group critique session, GFVs allowed commonly summative assessment stages to be seen as formative. This study contributes to existing literature through an application framework that may be used by design educators who are seeking to implement GFV methods within their own studio teaching practice. 相似文献
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Over the last decade, the assessment of student experience has gained significant prominence in Australian higher education. Universities conduct internal surveys in order to identify which of their services students rate higher or lower on importance and performance. Thus, institutions can promote highly performing areas and work on those needing improvement, while students are given an opportunity to influence decision-making in both academic and non-academic spheres of campus life. National student surveys conducted by the government aim to maintain quality assurance in the sector, benchmark outcomes, and, in some cases, reward better performing institutions. This paper outlines the findings of a study which monitored the entire student experience in a large metropolitan multi-campus university during 2005–2011. A specially designed biennial survey was repeated across the years, and completed over the period by 10,562 students from all key cohorts. This paper discusses the trends in perceived importance and performance of various university services and key issues the university has been addressing in order to enhance student experience. It concludes that: (a) the time series data provide a powerful lens into the university’s strategies, initiatives and actions which worked well and those needing further effort or adjustment; (b) it is the total experience of the university that shapes students’ judgements, not just what happens in the classroom; and (c) taking a systematic approach to student feedback, and acting on the results in a timely manner, can significantly improve student engagement and satisfaction. 相似文献
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Xiaowei Li Kejun Feng Long Li Lu Yang Xiaoshu Pan Hoda Safari Yazd Cheng Cui Juan Li Leonid Moroz Yujia Sun Bang Wang Xiang Li Tong Huang Weihong Tan 《国家科学评论(英文版)》2020,7(12):1933
Lipid–oligonucleotide conjugates (LONs) are powerful molecular-engineering materials for various applications ranging from biosensors to biomedicine. Their unique amphiphilic structures enable the self-assembly and the conveyance of information with high fidelity. In particular, LONs present remarkable potential in measuring cellular mechanical forces and monitoring cell behaviors. LONs are also essential sensing tools for intracellular imaging and have been employed in developing cell-surface-anchored DNA nanostructures for biomimetic-engineering studies. When incorporating therapeutic oligonucleotides or small-molecule drugs, LONs hold promise for targeted therapy. Moreover, LONs mediate the controllable assembly and fusion of vesicles based on DNA-strand displacements, contributing to nanoreactor construction and macromolecule delivery. In this review, we will summarize the general synthesis strategies of LONs, provide some characterization analysis and emphasize recent advances in bioanalytical and biomedical applications. We will also consider the relevant challenges and suggest future directions for building better functional LONs in nanotechnology and materials-science applications. 相似文献
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Dirt absorption on the ski running surface — quantification and influence on the gliding ability 总被引：2，自引：2，他引：0
We propose a thesis that minimising dirt on the running surface of skis improves the surface glide. Waxing usually improves the gliding ability of skis in the short term. But how does waxing affect pollution absorption in the long term? In this study a number of skis with a transparent base and a white background were treated by steel scraping and with different glide waxes. The gliding ability of waxed and unwaxed skis, the sliding surface whiteness and the hydrophobicity were tested and documented. Tests were performed before and after the skis had been used for different distances. It was observed that all the waxed skis (regardless of the wax used) absorbed more dirt than unwaxed, and as a result all waxed skis lose their glide ability sooner than unwaxed (freshly scraped) skis in wet snow conditions. 相似文献
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Alejandra Ferreira de Loza Manuel Jimenez-Lizarraga Leonid Fridman 《Journal of The Franklin Institute》2012,349(4):1416-1429
This paper tackles the problem of a two-player differential game affected by matched uncertainties with only the output measurement available for each player. We suggest a state estimation based on the so-called algebraic hierarchical observer for each player in order to design the Nash equilibrium strategies based on such estimation. At the same time, the use of an output integral sliding mode term (also based on the estimation processes) for the Nash strategies robustification for both players ensures the compensation of the matched uncertainties. A simulation example shows the feasibility of this approach in a magnetic levitator problem. 相似文献
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The problem of robust exact control for a Stewart platform with smooth bounded unknown inputs is considered. This platform has three degrees of freedom and it is used as a remote surveillance device. We consider high-order sliding mode observers to provide both theoretical exact observation and unknown input identification. In this paper, a methodology is proposed to select the most adequate control strategy for unknown external perturbation identification. The results obtained are illustrated by simulations. 相似文献