X-ray radiography and tomography for monitoring the penetration depth of consolidants in Opuka – the building stone of Prague monuments     

Monika Slavíková  František Krejčí  Jan Žemlička  Michal Pech  Petr Kotlík  Jan Jakůbek 《Journal of Cultural Heritage》2012,13(4):357-364

Stone consolidation is one of the major restoration treatments used for historical monuments preservation. A natural stone is a complicated heterogeneous porous system making the process of consolidation dependent on many variables. In practical restoration aims, for a given stone type, the selection of a suitable consolidant and consolidation conditions therefore remains a complex issue. The impregnation depth is a key factor for the assessment of the treatment efficiency. The combination of state-of-the-art hybrid pixel semiconductor detectors with newly available micro-focus X-ray sources makes possible to apply X-ray radiography, an ideal non-destructive tool, for penetration depth monitoring. In this study, high-resolution X-ray radiography is used for monitoring the penetration depth of organosilicon consolidants in the Opuka stone. The penetration depth has been evaluated in relation to the time of consolidation, stone porosity and consolidation mixtures properties. The exact influence of the X-ray contrast agent on the consolidation depth has been investigated as well. The information obtained provides supplementary knowledge on the suitability of investigated products for the treatment of this type of stone. In our study, the capabilities of X-ray radiography have been demonstrated on X-ray radiography simple projections, high-resolution computed tomography (CT) as well as on the dynamic processes monitoring. The results thus can serve also as an instrumental and methodological example applicable for consolidation monitoring of other stone types.  相似文献   

Iterative learning control for fractional-order multi-agent systems     

Dahui Luo  JinRong Wang  Dong Shen  Michal Fečkan 《Journal of The Franklin Institute》2019,356(12):6328-6351

In this paper, we apply iterative learning control to both linear and nonlinear fractional-order multi-agent systems to solve consensus tacking problem. Both fixed and iteration-varying communicating graphs are addressed in this paper. For linear systems, a PD^α-type update law with initial state learning mechanism is introduced by virtue of the memory property of fractional-order derivative. For nonlinear systems, a D^α-type update law with forgetting factor and initial state learning is designed. Sufficient conditions for both linear and nonlinear systems are established to guarantee all agents achieving the asymptotic output consensus. Simulation examples are provided to verify the proposed schemes.  相似文献   

Monitoring Acoustic Emission in an Epidemiological Pilot Study of a Collection of Wooden Objects     

Michal Łukomski  Vincent Beltran  Foekje Boersma  James Druzik  Ashley Freeman  Marcin Strojecki 《文物保护研究》2018,63(5):181-186

ABSTRACT

This experimental program, implemented by the Managing Collection Environment Initiative at the Getty Conservation Institute, has provided data about the response of historic objects to changes in relative humidity (RH). Alongside other less sensitive documentation techniques (visual observation, physical measurements, photography, and 3D scanning), acoustic emission (AE) was monitored for six historic, museum-like wooden objects exposed to gradually increasing RH variations. Quantitative calibration of AE sensors and an anti-correlation measuring scheme to reduce environmental noise allowed the AE system to effectively trace micro-damage development caused by environmentally induced stress. Using an epidemiological approach, with respect to sample selection and experimental protocol, the obtained results can be used to explore the acceptable range of climate fluctuations for museum collections. The study’s well-controlled environmental protocol also allowed for the examination of the concept of ‘proofed fluctuation’ by the analysis of object response to reoccurring conditions.  相似文献   

The contribution of morphological awareness to reading comprehension in early stages of reading     

Vered Vaknin-Nusbaum  Miri Sarid  Michal Raveh  Einat Nevo 《Reading and writing》2016,29(9):1915-1934

The contribution of morphological awareness to reading comprehension in Hebrew was studied in 298 second grade students who practiced two types of inflections, plural and possessive. Reading tasks at the beginning and end of the school year indicated that all improved on all tests in that period. Orthographic word recognition and morphological awareness predicted reading comprehension at the end of year. Students with low (LPD) and high (HPD) phonological decoding skills clearly differed qualitatively in reading comprehension. In the HPD students it was predicted by awareness of possessive inflections; in the LPD students it was predicted by orthographic word recognition ability. The results highlight the importance of examining the different components of morphological awareness in readers with different levels of phonological decoding ability.  相似文献   

Peer Tutoring, Metacognitive Processes and Multimedia Problem-based Learning: The Effect of Mediation Training on Critical Thinking     

Adina Shamir  Michal Zion  Ornit Spector_Levi 《Journal of Science Education and Technology》2008,17(4):384-398

The main objective of the study reported was to explore the effect on young children’s critical thinking of a peer-tutoring training embedded with the metacognitive processes required for problem-based learning and, consequently, for critical thinking. The sample consisted of 90 first- and third-grade pupils (45 pairs) randomly assigned to the experimental or control group. The experimental tutors received the Peer Mediation training, an intervention containing embedded metacognitive processes. The control children received a general preparation for peer-assisted learning. Following their respective preparations, all the children participated in a peer-tutoring condition, videotaped for 25 min and subsequently analyzed with an adaptation of the Newman et al. (Interpers Comput Technol 3(2):56–77, 1995) content analysis instrument. Analysis of the discourse conducted during the tutoring session indicated that the tutors and tutees in the experimental groups exhibited greater depth of critical thinking, demonstrated in the higher Quality of Discourse Ratio calculated, than did the tutors and tutees in the control group. The findings supported previous results showing the efficacy of the Peer Mediation for Young Children mediation-training program, with its embedded metacognitive competencies, for reinforcing young children’s higher-order thinking. Implications for educators are discussed.  相似文献   

Plans are nothing, changing plans is everything: the impact of changes on project success     

Dov Dvir 《Research Policy》2004,33(1):1-15

Based on a sample of 448 projects, the interactions between three project planning variables, the quality of planning, goal changes, plan-changes and project success are analyzed. The most important results of this study are the interactions between the planning variables and their influences on project success. By using structural equation modeling, we gained insight into these complex indirect relationships. The results clearly show that the positive total effect of the quality of planning is almost completely overridden by the negative effect of goal changes. If we add the total effects of goal changes and plan-changes on project success, their combined effect is considerably stronger than that of the quality of planning. The study also identifies several contextual variables affecting the planning process.  相似文献   

Use of Anthocyanin Profiles When Differentiating Individual Varietal Wines and Terroirs     

Michal Kum?ta  Pavel Pavlou?ek  Pavel Kárník 《Food Technology and Biotechnology》2014,52(4):383-390

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Capacity and Flexibility in Community College CTE Programs: Program Offerings and Student Success     

Grosz  Michel  Kurlaender  Michal  Stevens  Ann 《Research in higher education》2022,63(1):140-188

Research in Higher Education - This article asks whether small changes to community college courses and programs can help improve student outcomes. We use administrative data from the California...  相似文献   

School bullying and students’ sense of safety in school: the moderating role of school climate     

Zacharia  Michal Goldberg  Yablon  Yaacov B. 《European Journal of Psychology of Education - EJPE》2022,37(3):903-919

European Journal of Psychology of Education - One of the negative consequences of bullying in schools is its adverse effect on students’ sense of safety. Previous studies yielded mixed...  相似文献   

Do siblings influence one another? Unpacking processes that occur during sibling conflict     

Sahar Borairi  Andre Plamondon  Michelle Rodrigues  Nina Sokolovic  Michal Perlman  Jennifer Jenkins 《Child development》2023,94(1):110-125

This study examined the extent to which 205 sibling dyads influenced each other during conflict. Data were collected between 2013 to 2015. The sample included 5.9% Black, 15.1% South Asian, 15.1% East Asian, and 63.8% White children. Older siblings were between 7–13 years old (Female = 109) and younger siblings were 5–9 years old (Female = 99). Siblings' conflict resolution was analyzed using dynamic structural equation modeling. Modeling fluctuations in moment-to-moment data (20-s intervals) allowed for a close approximation of causal influence. Older and younger siblings were found to influence one another. Younger sisters were more constructive than younger brothers, especially in sister–sister dyads. Sibling age gap predicted inertia in older siblings. Socialization processes within sibling relationships are discussed.  相似文献