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In this paper a new integrated observer-based fault estimation and accommodation strategy for discrete-time piecewise linear (PWL) systems subject to actuator faults is proposed. A robust estimator is designed to simultaneously estimate the state of the system and the actuator fault. Then, the estimate of fault is used to compensate for the effect of the fault. By using the estimate of fault and the states, a fault tolerant controller using a PWL state feedback is designed. The observer-based fault-tolerant controller is obtained by the interconnection of the estimator and the state feedback controller. We show that separate design of the state feedback and the estimator results in the stability of the overall closed-loop system. In addition, the input-to-state stability (ISS) gain for the closed-loop system is obtained and a procedure for minimizing it is given. All of the design conditions are formulated in terms of linear matrix inequalities (LMI) which can be solved efficiently. Also, performance of the estimator and the state feedback controller are minimized by solving convex optimization problems. The efficiency of the method is demonstrated by means of a numerical example. 相似文献
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Seyed Mohammad Ali Taghavi 《Culture, Theory & Critique》2013,54(2):123-138
Although Richard Rorty's controversial thought has been the subject of many works, there has not been much discussion about his approach to cultural difference. The purpose of this article is to examine how Rorty sees cultural differences philosophically and how he deals with them politically. For him, rationality, morality and even the scope of moral responsibility towards others are defined in terms of solidarity with a particular community and ‘ethnocentrism’, rather than in terms of a universal and metaphysically derived set of criteria. It can be argued that since language, language games and values are mainly components of culture, the latter is one of the most significant communities with which Rorty is concerned, though he is not explicit about it. Nevertheless, Rorty does not think that the moral and philosophical significance of communities, particularly cultural communities, should be reflected in politics. The main argument of the article is that there is an unresolved tension in Rorty's thought between philosophical, moral and emotional attribution of significance to communities and arguably cultural communities, and a disregard for them in the political sphere. This paves the way for outlining an approach to cultural difference that is more just and even more in harmony with Rorty's own philosophy. 相似文献
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Within the context of Information Extraction (IE), relation extraction is oriented towards identifying a variety of relation phrases and their arguments in arbitrary sentences. In this paper, we present a clause-based framework for information extraction in textual documents. Our framework focuses on two important challenges in information extraction: 1) Open Information Extraction and (OIE), and 2) Relation Extraction (RE). In the plethora of research that focus on the use of syntactic and dependency parsing for the purposes of detecting relations, there has been increasing evidence of incoherent and uninformative extractions. The extracted relations may even be erroneous at times and fail to provide a meaningful interpretation. In our work, we use the English clause structure and clause types in an effort to generate propositions that can be deemed as extractable relations. Moreover, we propose refinements to the grammatical structure of syntactic and dependency parsing that help reduce the number of incoherent and uninformative extractions from clauses. In our experiments both in the open information extraction and relation extraction domains, we carefully evaluate our system on various benchmark datasets and compare the performance of our work against existing state-of-the-art information extraction systems. Our work shows improved performance compared to the state-of-the-art techniques. 相似文献
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Fatemeh Lashkari Ebrahim Bagheri Ali A. Ghorbani 《Information processing & management》2019,56(3):733-755
Traditional information retrieval techniques that primarily rely on keyword-based linking of the query and document spaces face challenges such as the vocabulary mismatch problem where relevant documents to a given query might not be retrieved simply due to the use of different terminology for describing the same concepts. As such, semantic search techniques aim to address such limitations of keyword-based retrieval models by incorporating semantic information from standard knowledge bases such as Freebase and DBpedia. The literature has already shown that while the sole consideration of semantic information might not lead to improved retrieval performance over keyword-based search, their consideration enables the retrieval of a set of relevant documents that cannot be retrieved by keyword-based methods. As such, building indices that store and provide access to semantic information during the retrieval process is important. While the process for building and querying keyword-based indices is quite well understood, the incorporation of semantic information within search indices is still an open challenge. Existing work have proposed to build one unified index encompassing both textual and semantic information or to build separate yet integrated indices for each information type but they face limitations such as increased query process time. In this paper, we propose to use neural embeddings-based representations of term, semantic entity, semantic type and documents within the same embedding space to facilitate the development of a unified search index that would consist of these four information types. We perform experiments on standard and widely used document collections including Clueweb09-B and Robust04 to evaluate our proposed indexing strategy from both effectiveness and efficiency perspectives. Based on our experiments, we find that when neural embeddings are used to build inverted indices; hence relaxing the requirement to explicitly observe the posting list key in the indexed document: (a) retrieval efficiency will increase compared to a standard inverted index, hence reduces the index size and query processing time, and (b) while retrieval efficiency, which is the main objective of an efficient indexing mechanism improves using our proposed method, retrieval effectiveness also retains competitive performance compared to the baseline in terms of retrieving a reasonable number of relevant documents from the indexed corpus. 相似文献
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Nahid Shirani Bidabadi Ebrahim Mirshah Jafari Ahmad Abedi 《The Journal of educational research》2019,112(3):421-428
The authors investigated the effect of a mathematical curriculum (CU) developed based on verbal and practical activities on the mathematical competency (MC) and learning behaviors (LB) of preschool children. In a quasi-experimental design, 60 children (5- to 6-year-old girls) were selected using the accessible sampling method. The children were randomly divided into an experimental group and a control group, and the relevant concepts were taught to the children in both groups. While the control group received the typical kindergarten education based on the usual textbooks and worksheets, the CU was taught to the experimental group. Structural equation modeling was used to model the data and statistical evaluation. The results demonstrated a significant difference between the two groups in MC and LB. The CU significantly improved MC directly, and indirectly through the improvement of LB (i.e., engagement and learning focus, verbal behaviors, and type of activity). 相似文献
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Bahram Vazirnezhad Farshad Almasganj Seyed Mohammad Ahadi Ari Chanen 《浙江大学学报(A卷英文版)》2009,10(10):1461-1475
Speaker variability is an important source of speech variations which makes continuous speech recognition a difficult task. Adapting automatic speech recognition （ASR） models to the speaker variations is a well-known strategy to cope with the challenge, Almost all such techniques focus on developing adaptation solutions within the acoustic models of the ASR systems. Although variations of the acoustic features constitute an important portion of the inter-speaker variations, they do not cover variations at the phonetic level. Phonetic variations are known to form an important part of variations which are influenced by both micro-segmental and suprasegmental factors. Inter-speaker phonetic variations are influenced by the structure and anatomy of a speaker＇s articulatory system and also his/her speaking style which is driven by many speaker background characteristics such as accent, gender, age, socioeconomic and educational class. The effect of inter-speaker variations in the feature space may cause explicit phone recognition errors. These errors can be compensated later by having appropriate pronunciation variants for the lexicon entries which consider likely phone misclassifications besides pronunciation. In this paper, we introduce speaker adaptive dynamic pronunciation models, which generate different lexicons for various speaker clusters and different ranges of speech rate. The models are hybrids of speaker adapted contextual rules and dynamic generalized decision trees, which take into account word phonological structures, rate of speech, unigram probabilities and stress to generate pronunciation variants of words. Employing the set of speaker adapted dynamic lexicons in a Farsi （Persian） continuous speech recognition task results in word error rate reductions of as much as 10.1% in a speaker-dependent scenario and 7.4% in a speaker-independent scenario. 相似文献
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In this study, the efficiency of bitumen and asphalt mixtures modified with crumb rubber （CR） and recycled glass powder （RGP） is evaluated. From an environmental point of view, the application of RGP in asphalt mixtures is considered beneficial since it prevents accumulation of waste glass in the natural environment. Rheological and mechanical properties of modified bitumen samples were investigated by laboratory methods such as bitumen conventional tests and dynamic shear rheometer （DSR）, and also by asphalt mixture performance tests including Marshall stability, indirect tensile strength （ITS）, compressive strength, and indirect tensile stiffness modulus. The results showed that the application of RGP in place of CR has no negative impact on the efficiency of bitumen and asphalt mixtures and even improves their engineering properties except for the toughness index （TI）. Moreover, a modification with 5% CR and 5% RGP in asphalt mixtures results in the best overall performance. 相似文献
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Fawzy Ebrahim 《Roeper Review》2013,35(3):140-147
This study focuses on comparing the creative thinking and reasoning abilities of deaf and hearing children. Two groups of deaf (N = 210) and hearing children (N = 200) were chosen based on specific criteria. Two instruments were used in the study: theTorrance Tests of Creative Thinking‐Figural, Form A and Matrix Analogous Test. Canonical Correlation analysis and multivariate analysis of variance (MANOVA) were used to analyze the data. The canonical correlation analyses revealed one significant dimension in both deaf and hearing children. The multivariate analysis of variance (MANOVA) revealed that there are some similarities and differences between the deaf and hearing samples regarding creative thinking abilities. 相似文献
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Emergent patterns of teaching/learning in electronic classrooms 总被引：1，自引：0，他引：1
Ben Shneiderman Ellen Yu Borkowski Maryam Alavi Kent Norman 《Educational technology research and development : ETR & D》1998,46(4):23-42
Novel patterns of teaching/learning have emerged from faculty and students who use our three teaching/learning theaters at
the University of Maryland, College Park. These fully-equipped electronic classrooms have been used by 74 faculty in 264 semester-long
courses since the fall of 1991 with largely enthusiastic reception by both faculty and students. The designers of the teaching/learning
theaters sought to provide a technologically rich environment and a support staff so that faculty could concentrate on changing
the traditional lecture from its unidirectional information flow to a more collaborative activity. As faculty have evolved
their personal styles in using the electronic classrooms, novel patterns of teaching/learning have emerged. In addition to
enhanced lectures, we identified three common patterns: (a) active individual learning, (b) small-group collaborative learning,
and (c) entire-class collaborative learning. 相似文献