History-dependent modified sliding mode interception strategies with maximal capture zone     

Valery Y. Glizer  Vladimir Turetsky  Leonid Fridman  Josef Shinar 《Journal of The Franklin Institute》2012,349(2):638-657

In order to construct the guidance strategy in a realistic nonlinear noise-corrupted interception endgame against a maneuverable target, a linearized zero-sum differential game is considered. Assuming perfect information in this game, sufficient conditions are established, which guarantee that a continuous interception strategy with memory (history-dependent) has the maximal capture zone. Two examples of such a strategy are analyzed: a modified super-twisting second-order sliding mode control and a modified integral sliding mode control. Simulation results of the original nonlinear interception endgame demonstrate that these strategies considerably reduce the chattering created by the classical game optimal bang-bang strategy without deteriorating the homing performance.  相似文献   

Entity ranking in Wikipedia: utilising categories,links and topic difficulty prediction     

Jovan Pehcevski  James A. Thom  Anne-Marie Vercoustre  Vladimir Naumovski 《Information Retrieval》2010,13(5):568-600

Entity ranking has recently emerged as a research field that aims at retrieving entities as answers to a query. Unlike entity extraction where the goal is to tag names of entities in documents, entity ranking is primarily focused on returning a ranked list of relevant entity names for the query. Many approaches to entity ranking have been proposed, and most of them were evaluated on the INEX Wikipedia test collection. In this paper, we describe a system we developed for ranking Wikipedia entities in answer to a query. The entity ranking approach implemented in our system utilises the known categories, the link structure of Wikipedia, as well as the link co-occurrences with the entity examples (when provided) to retrieve relevant entities as answers to the query. We also extend our entity ranking approach by utilising the knowledge of predicted classes of topic difficulty. To predict the topic difficulty, we generate a classifier that uses features extracted from an INEX topic definition to classify the topic into an experimentally pre-determined class. This knowledge is then utilised to dynamically set the optimal values for the retrieval parameters of our entity ranking system. Our experiments demonstrate that the use of categories and the link structure of Wikipedia can significantly improve entity ranking effectiveness, and that topic difficulty prediction is a promising approach that could also be exploited to further improve the entity ranking performance.  相似文献   

Testing Inequality Constrained Hypotheses in SEM Models     

Rens van de Schoot  Herbert Hoijtink  Maja Deković 《Structural equation modeling》2013,20(3):443-463

Researchers often have expectations that can be expressed in the form of inequality constraints among the parameters of a structural equation model. It is currently not possible to test these so-called informative hypotheses in structural equation modeling software. We offer a solution to this problem using Mplus. The hypotheses are evaluated using plug-in p values with a calibrated alpha level. The method is introduced and its utility is illustrated by means of an example.  相似文献   

Towards new learning environments—Collective civic actions as learning interventions in post-Communist Belgrade     

Katarina Popović  Maja Maksimović  Aleksa Jovanović 《European Journal of Education》2018,53(3):365-376

This article focuses on the social dimension of well-being, based on a critical analysis of the way it is conceptualised in late capitalism: As the dimensions of individual state of mind and body, something that evolves in the individual realm, stressing personal responsibility and achievement of well-being as a solitary act. Then, the contemporary conceptualisation and approaches to policy making for well-being are compared with the policy of adult and youth education and learning. The perspective of a strong individual orientation, detachment from the social, community and collective aspects and efforts seem to be a common denominator. Agency is considered not only as a possibility for individuals to create and change the environment, but also as a process of active co-construction of social reality. This includes (re)connection with a community, very often through new ways of community learning, civic actions and civic activities. An analysis of how these perspectives converge in civic interventions in urban areas of Belgrade places togetherness at the core of the broader approach to well-being and learning. This article presents several examples of civic activities in urban spaces whose learning character is interpreted within the concept of public pedagogy. The examples presented prevail in the post-Communist countries because public spaces as zones of civic interventions can oppose the controlling authority and through the fight for human and civil rights represent the bottom line of togetherness and collective agency. Learning through collective civic actions thus provides new ways of understanding well-being.  相似文献   

Authors from the periphery countries choose open access more often          下载免费PDF全文

Witold Kieńć 《Learned Publishing》2017,30(2):125-131

This article analyses attitudes of academic authors toward open access (OA) and the frequency of choosing OA publication venues. The research looks particularly at differences between authors based in countries with a gross domestic product per capita less or greater than US$18,000 (called periphery and core countries, respectively). The data were obtained with an online survey sent to 107,296 scholars listed on the mailing lists belonging to De Gruyter Open from December 2015 to January 2016. A total of 1,012 responses were received. Authors from the periphery countries publish their articles in gold OA more often and they also pay OA publication fees equally often as those based in the core countries. The reasons for that are complex, involving both their preference to publish in OA and the composition of the publishing market in the periphery.  相似文献   

Cytocompatible cellulose nanofibers from invasive plant species Agave americana L. and Ricinus communis L.: a renewable green source of highly crystalline nanocellulose     

Evdokimova  Olga L.  Alves  Carla S.  Krsmanović Whiffen  Radenka M.  Ortega  Zaida  Tomás  Helena  Rodrigues  João 《Journal of Zhejiang University. Science. B》2021,22(6):450-461

In this study, the fibers of invasive species Agave americana L. and Ricinus communis L. were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers. Cellulose nanofibers were obtained by two methods, based on either alkaline or acid hydrolysis. The morphology, chemical composition, and crystallinity of the obtained materials were characterized by scanning electron microscopy(SEM) together with energy-dispersive X-ray spectroscopy(EDX), dynamic light scattering(DLS), X-ray diffraction(XRD), and Fourier transform infrared(FTIR)spectroscopy. The crystallinity indexes(CIs) of the cellulose nanofibers extracted from A. americana and R. communis were very high(94.1% and 92.7%, respectively). Biological studies evaluating the cytotoxic effects of the prepared cellulose nanofibers on human embryonic kidney 293 T(HEK293 T) cells were also performed. The nanofibers obtained using the two different extraction methods were all shown to be cytocompatible in the concentration range assayed(i.e., 0-500 μg/mL). Our results showed that the nanocellulose extracted from A. americana and R. communis fibers has high potential as a new renewable green source of highly crystalline cellulose-based cytocompatible nanomaterials for biomedical applications.  相似文献   

Evaluation of Energy Saving Operational Modes for Industrial Fracture Connected Processes on the Basis of Incubation Time Fracture Criterion     

Bratov Vladimir  Petrov Yuri 《天津大学学报(英文版)》2008,(Z1)

A problem for a central crack in a plate subjected to plane strain conditions is investi-gated. Mode Ⅰ crack loading is created by a dynamic pressure pulse applied at a large distance from the crack. It was found that for a certain combination of amplitude and duration of the pulse applied, the energy transmitted to the sample has a strongly marked minimum, meaning that with the pulse amplitude or duration moving away from the optimal values, minimum energy required for initiation of crack growth increases rapidly. The results obtained indicate a possibility to optimise energy consumption of different industrial processes connected with fracture. Much could be gained in, for example, drilling or rock pounding where energy input accounts for the largest part of the process cost. Presumably further investigation of the effect observed can make it possible to predict optimal energy saving parameters, i.e. frequency and amplitude of impacts, for industrial devices, e.g. bores, grinding machines, and hence significantly reduce the process cost. The pre-diction can be given based on the parameters of the media fractured (material parameters, preva-lent crack length and orientation, etc.).  相似文献   

Um Compasso Para Aprender: A Randomized Trial of a Social-Emotional Learning Program in Homicide-Affected Communities in Brazil     

Dana C. McCoy  Emily C. Hanno  Vladimir Ponczek  Cristine Pinto  Gabriela Fonseca  Natália Marchi 《Child development》2021,92(5):1951-1968

Despite global demand, the large-scale effects of social-emotional learning (SEL) programming in developing countries remain underexplored. Using a randomized control trial, this study examined the effectiveness of a school-wide SEL intervention—Programa Compasso (PC)—among 3,018 sociodemographically diverse, Portuguese-speaking children (M_age = 9.85 years) attending 90 public primary schools across Rio de Janeiro, Brazil in 2017. Average impacts of PC on children’s executive function, emotion knowledge, and behavior problems after one school year were null. Moderation analyses did, however, reveal evidence for positive impacts of PC on children’s labeling of emotional expressions and inhibitory control within low-homicide communities (d = 0.15 SDs), and null effects on these same outcomes in high-violence areas. Implementation and cultural considerations are discussed.  相似文献   

Maris: A knowledge system for internal medicine     

Vladimir Slamecka  Henry N. Camp  Albert N. Badre  W. Dallas Hall 《Information processing & management》1977,13(5):273-276

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Depictions of Human Bodies in the Illustrations of Early Childhood Textbooks     

Vladimir E. Martínez-Bello  Daniel A. Martínez-Bello 《Early Childhood Education Journal》2016,44(2):181-190

In many Ibero-American countries children in the early childhood education (ECE) system have the opportunity to interact with textbooks on a regular basis. The powerful social function of textbooks in socializing children in primary and secondary school, and in legitimizing what counts as cultural norms and officially sanctioned values and knowledge, is clearly documented. However, the examination of ECE textbooks especially in the context of developing countries for messages about the social construction of the body is virtually nonexistent. Therefore, the purpose of this research was to examine, through a content analysis of the illustrations, the representation of the body across the different categories of gender, age, activity level, space and disability in eight Colombian ECE textbooks from the three major commercial publishing houses between 2009 and 2012. Our results show that these textbook authors and publishers have made an effort to promote equality between the genders. However, only four disabled people were portrayed in the illustrations and there was a lower proportion of older adults doing a limited range of gross motor activities. Likewise the results note that, although progress has been made in terms of the balance of gender representation in textbooks, these still reinforce and legitimize the status of the “able-body”, and contribute to consolidating a view of able-bodiedness as the dominant norm. Taking into account that beliefs and prejudices constitute barriers to education and social participation, these results suggest that the representation of children with disabilities in ECE textbooks at the earliest stages of education should be mandatory.  相似文献