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1.
Nine limiting binaries of Al2O3-SiO2-Re2O3(Re=Nd, Sm, Gd and La) system are assessed. The binary diagrams or experimental information from Toropov, Mizuno, Aramaki, Bondar, Rolin and Coutures are optimized with the substitutional model of Kaufman and Nesor and the approximate formula of fusion free energy for rare earth element oxides of Wu and Pelton. The extracted Gibbs free energies of pure solid oxides and stoichiometric phases and the solution parameters are used to estimate the corresponding binaries, liquidus surfaces and a series of isothermal sections of four ternaries Al2O3-SiO2-Nd2O3, Al2O3-SiO2-Sm2O3, Al2O3-SiO2-Gd2O3, and Al2O3-SiO2-La2O3. In the Al2O3-SiO2-Gd2O3 system samples as fired at exact temperature with different compositions were analyzed by X-ray diffractometer and the detected results are fitted with the calculation of isothermal sections. Supported by State Key Lab of High Performance Ceramics and Superfine Micro-structure (9517 and 9708)  相似文献   

2.
This study examined differential and mediating relations between hot and cool self-regulation (Mage = 48.2 months; N = 1,155, 48% girls), first-grade (Mage = 77.5 months) maladjustment (externalizing [EXT] and internalizing [INT] behavior), and first- and second-grade (Mage = 89.5 months) academic competence (AC). Using teacher reported EXT, INT, and AC, partial support for the differential perspective was found in that only hot self-regulation was significantly related to EXT, whereas both hot and cool self-regulation was significantly related to AC. Moreover, hot self-regulation indirectly predicted second-grade AC through first-grade EXT, lending some support for the mediating perspective also. The findings contribute to an understanding of how self-regulation is related to academic and behavioral school adjustment.  相似文献   

3.
LetH n be the set of real algebraic polynomials of degreen, whose zeros all lie in the interval [−1,1]. The well known Turán type inequalities tell us that forf(x)∈H n , it holds ‖f′‖≥C√n‖f‖. This note deals with the weighted Turán type inequalities with the weights having inner singularities underL p norm for 0<p≤∞. Our results essentially extend the result of Wang and Zhou (2002), and the method used in this paper is simpler and more direct than that of Wang and Zhou (2002). The results and methods have their own values in approximation theory and computation.  相似文献   

4.
Consider the positive d-dimensional lattice d (d≥2) with partial ordering ≤, let {XK; K ∈ d } be i.i.d. random vari- ables taking values in a real separable Hilbert space (H, ||·||) with mean zero and covariance operator ∑, and set partial sums SN =∑K≤NXK, K , N ∈ d . Under some moment conditions, we obtain the precise asymptotics of a kind of weighted infinite series for partial sums SN as ε 0 by using the truncation and approximation methods. The results are related to the convergence rates of the law of the logarithm in Hilbert space, and they also extend the results of (Gut and Spǎtaru, 2003).  相似文献   

5.
Infrared （IR） absorption spectra and X-ray powder diffraction （XRD） patterrns of sexpenfine cat＇s eye from Sichuan Province have been investigated, and infrared absorption bands of the serpentine have been assigned in this paper. The results indicate that the bands near 3 600 - 3 700 cm^-1 belong to the stretching absorption band VOH, the bands in 948 - 1 100 cm^-1 axe assigned to the stretching vibraling band Usvo, and the bands at 600 570 and 440 cm^-1 respectively belong to the bending vibration band VOH, δMg-O and δSi-O. The serpentine cat＇ s eye includes two types： chrysotile and antigorite. Chrysotile has a sharp and intensive band at 3 688 cm^-1 and a weak band at 3 643 cm^-1 , while antigorite has only one intensive band in the region. At vibration band VSi-O, chrysotile and antigorite have a similar feature at 1 071 cm^-1, but the band at 980 cm^-1 in anfigorite has been split into two bands in chrysotile - a strong one at 1 027 cm^-1 and a weak one at 949 cm^-1. In addition, antigorite has a characteristic bending vibrating band δMg-O at 570 cm^-1. Based on the analysis of the feature of crystal structure, their IR differences axe well explained.  相似文献   

6.
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7.
In this paper, we consider some polynomial (α,β)-metrics, and discuss the sufficient and necessary conditions for a Finsler metric in the form F=α a1β a2β2/α a4β4/α3 to be projectively flat, where ai (i=1,2,4) are constants with a1≠0, α is a Riemannian metric and β is a 1-form. By analyzing the geodesic coefficients and the divisibility of certain polynomials, we obtain that there are only five projectively flat cases for metrics of this type. This gives a classification for such kind of Finsler metrics.  相似文献   

8.
Consider the mixed-effect coefficient semiparametric regression modelZ=X'α+Y'β+g(T)+e, whereX, Y andT are random vectors onR p×R q×[0, 1], α is a p-dimensional fixed-effect parameter, β is a q-dimensional random-effect parameter (Eβ=b, Cov(β)=Σ),g(.) is an unknown function on [0, 1], e is a random error with mean zero and variance σ2, and (X, Y, T) and (β,e), β ande are mutually independent. We estimate α,b andg(.) by the nearest neighbor and the least square method. In this paper, we prove that estimations of α,b have asymptotic normality and obtain the best convergence raten −1/3 for the estimation ofg(.). Project supported by the NSFC and the Natural Science Foundation of Zhejiang Province.  相似文献   

9.
Using SnxTi1-xO2 as carriers, CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide (CuO) were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 were examined using a microreactor-gas chromatography (GC) NO CO reaction system and the methods of BET (Brun- auer-Emmett-Teller), TG-DTA (themogravimetric and differential thermal analysis), X-ray diffraction (XRD) and H2-temperature programmed reduction (TPR). The results showed that NO conversions of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT (Brunauer, Deming, Deming and Teller) system and a typical mesoporous sample. There were two CuO diffraction peaks (2θ 35.5° and 38.7°), and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks (α, β and γ) from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the γ peak was the reduction of crystal phase copper oxide. In addition, a fourth peak (δ) of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.  相似文献   

10.
Functions like loge x, e x , e z and loge z are defined and studied systematically. It is observed thate z is the only complex analytic extension of the real analytic functione x . It is also observed that the power (analyticity) of ez is by choice and the beauty (its derivative is itself) of ez is unexpected.  相似文献   

11.
This article explores how incarcerated youth and adult supervisors contest claims to identity via language of “representing”. Comparing how youth and adults “represent” in discussions of their own past and future selves sheds light on the constrained universe of discourse within which both groups work to express identities and on the basis of which we counsel, mentor, and educate young people. Acknowledging these constraints can contribute to understanding what I call exceptionalism—the idea that only exceptional poor and raced young men, through great personal effort and sacrifice, may resist the lure of the “street”. I conclude by discussing implications of this work for education and youth development work both inside and beyond the juvenile justice system as well as for research across lines of difference by committed “outsiders”.
Joby GardnerEmail:
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12.
The aim of the present study was to identify children’s conceptions of learning mathematics and to assess the identified conceptions. Children’s conceptions are identified by interviewing 73 grade 5 students in Taiwan. The interviews are analyzed using qualitative data analysis methods, which results in a structure of 5 major conceptions, each having 2 subconceptions: constructivist (interest and understanding), interpretivist (liberty and innovation), objectivist (academic goal and perseverance), nativist (confidence and anxiety (reverse)), and pragmatist (vocational goal and application). The conceptions are assessed with a self-developed questionnaire, titled “the Conception of Learning Mathematics Questionnaire” (CLMQ), which is administered to 513 grade 5 students in Taiwan and examined with a reliability measure, confirmatory factor analysis, and correlations with 2 criteria: mathematics achievement and approaches to learning mathematics. The results show that the CLMQ has desirable internal consistency reliability and construct validity. The conceptions are also sensibly in relation to the 2 criteria, suggesting that the CLMQ is a valid measure for evaluating the quality of children’s learning mathematics in relation to teaching contexts.  相似文献   

13.
Due to the modernization of the medical curriculum and technological advancements, anatomy education has evolved beyond cadaveric dissection alone. Plastination techniques, three-dimensional (3D) modeling, and 3D printing technologies have progressively gained importance. However, there are limited valid and reliable surveys to evaluate students' perceptions of these new anatomy tools. Hence, this study aimed to develop a validated instrument to measure students' learning satisfaction, self-efficacy, humanistic values, and perceived limitations of plastinated and 3D printed models. A 41-item survey (five-point Likert scale, 1 = strongly disagree to 5 = strongly agree) was administered to Year 1 undergraduate medical students following a randomized controlled crossover study that evaluated plastinated and 3D printed cardiac and neck models. Ninety-six responses were received, and a factor analysis was performed with the Kaiser–Meyer–Olkin sampling adequacy of 0.878. The confirmatory factor analysis yielded a 4-factor, 19 items model that had a good fit with the latent constructs of x2 (147) = 211.568, P < 0.001, root mean square error of approximation = 0.068, root mean square residual = 0.064, comparative fit index = 0.946, and Tucker Lewis index = 0.937. The Cronbach's alpha for the individual factors ranged from 0.74 to 0.95, indicating good internal consistency. This demonstrated a psychometrically valid and reliable instrument to measure students' perceptions toward plastinated and 3D printed models.  相似文献   

14.
We derive necessary and sufficient conditions for the existence and an expression of the （anti）reflexive solution with respect to the nontrivial generalized reflection matrix P to the system of complex matrix equations AX = B and XC = D. The explicit solutions of the approximation problem min x∈Ф ｜｜X - E｜｜F was given, where E is a given complex matrix and Ф is the set of all reflexive （or antireflexive） solutions of the system mentioned above, and ｜｜·｜｜ is the Frobenius norm. Furthermore, it was pointed that some results in a recent paper are special cases of this paper.  相似文献   

15.
The delivery of quality education to elementary school students in remote and isolated areas continues to be a major problem in most countries. Solutions to this problem should be inexpensive, easy to develop and implement, and straightforward enough for local educational officials and teachers to understand and use. The Small Schools Project of the Indonesian Ministry of Education is attempting to solve this problem through an imaginative programme unique in its provision of an interrelated group of educational interventions of proven effectiveness. These interventions are: self-paced learning modules covering basic subject matter areas, self-paced evaluation for the content covered, learning groups of six to eight students led by peer tutors, supportive rather than didactic teacher behaviours and regular teacher training sessions to impart these behaviours, active support from the community, repair of school buildings, a small number of carefully chosen supplementary materials, larger teaching staffs, planning which integrates a variety of government offices at different levels, cooperative arrangements with universities and teacher training high schools, continuous formative evaluation, and a handbook which describes programme materials, policies and procedures. Preliminary evaluation indicates that the programme is succeeding. The problems of educating isolated youth are strikingly similar across cultures and temporal periods, and given the universality of this problem, other imaginative solutions should be studied and the results of these studies disseminated.
Zusammenfassung Für die meisten Länder ist es immer noch ein Schlüsselproblem, Elementarschülern in abgelegenen und isolierten Gegenden Unterricht von angemessener Qualität zu erteilen. Lösungen dieses Problems sollten nicht kostspielig, einfach zu entwickeln und durchzuführen und für örtliche Erziehungsbeamte und Lehrer leicht verständlich und anwendbar sein. Das Kleinschulprojekt des indonesischen Erziehungsministeriums bemüht sich, dieses Problem durch ein phantasiereiches Programm zu lösen, das in seiner Vorkehrung einzigartig ist, Gruppen durch erzieherische Maßnahmen von bewährter Wirksamkeit miteinander zu verbinden. Diese Maßnahmen sind: selbstgesteuerte Bausteine, die Grundthemen der Gegenstandsbereiche abdecken, selbstgesteuerte Bewertung der Lerninhalte, Lerngruppen von sechs bis acht Schülern unter Leitung gleichaltriger Tutoren, ein Lehrerverhalten, das mehr anregend als belehrend ist und regelmäßige Fortbildungsveranstaltungen, um die Lehrer mit diesem Verhalten vertraut zu machen, aktive Unterstützung durch die Gemeinden, Ausbesserungen der Schulgebäude, eine geringe Anzahl sorgfältig ausgewählten, zusätzlichen Materials, größere Lehrerkollegien, eine Planung, die eine Vielzahl von Regierungsbehörden auf verschiedenen Ebenen, untereinander verbendet, Vereinbarungen zur Zusammenarbeit zwischen Universitäten und höheren Schulen zur Lehrerausbildung, fortgesetzte Bildungsbewertung und ein Handbuch, das Lehrmateriale, Richtlinien und Verfahren beschreibt. Eine Zwischenauswertung hat ergeben, daß dieses Programm erfolgreich ist. Die Probleme, isolierte Jugendliche zu unterrichten, weisen auffallende Ähnlichkeiten in verschiedenen Kulturbereichen und zu verschiedenen Zeitepochen auf. Angesichts der Universalität dieses Problems sollten andere phantasiereiche Lösungen untersucht und die Ergebnisse dieser Berichte verbreitet werden.
Résumé Dispenser un enseignement de qualité aux élèves des classes élémentaires se trouvant dans des zones reculées et lointaines reste un grand problème dans de nombreux pays. Les solutions à ce problème ne doivent pas être onereuses, mais faciles à développer et à réaliser; elles doivent être assez simples à comprendre et à utiliser pour les administrations locales de l'éducation et les enseignants. Le Projet du Ministère de l'Education indonésien concernant l'école élémentaire vise à résoudre ce problème à travers un programme ingénieux et unique en son genre par l'offre d'un ensemble étroitement lié d'interventions éducatives d'une efficacité pédagogique reconnue. Ces moyens sont: des éléments pour l'auto-apprentissage couvrant les matières fondamentales; une auto-évaluation du contenu donné, des groups d'apprentissage de six à huit élèves avec des répétiteurs de même niveau, des enseignants adoptant un comportement plutôt d'assistance que didactique, des sessions régulières de formation des enseignants afin de transmettre ces comportments, un aide active des communes, la réparation des établissements scolaires, un petit nombre de matériels pédagogiques soigneusement choisis, un personnel plus nombreux, une planification qui intègre une quantité d'institutions publiques à différents niveaux, des arrangements prévoyant une coopération entre universités et écoles de pédagogie, une évaluation continue de la formation, et un manuel décrivant les materiels du programme, les buts et les procédés. Une première évaluation montre que le programme est prometteur. Les problèmes d'éducation des jeunes vivant dans des régions isolées sont très similaires à travers les différentes cultures et à travers tous les temps, ainsi, étant donné l'universalité de ce problème, d'autres solutions astucieuses devraient être étudiées et les résultats de ces études diffusés.
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16.
Résumé De manière générale, l'évidence sensorielle et, plus particulièrement, visuelle constitue pour les étudiants le principal fondement du savoir scientifique: nul besoin de supposer pour connaître, tout est donné ou presque. Du point de vue de l'enseignement des sciences, cette croyance à saveur réaliste est particulièrement critique, notamment parce qu'elle conduit à penser que les concepts, lois et théories scientifiques procèdent d'un monde de matérialités plutôt que d'un monde de modèles et de relations. Au cours d'une recherche effectuée auprès d'un groupe-classe de 35 étudiants durant douze semaines, nous avons pu observer que, pour la majorité des étudiants, la compréhension du caractère construit et consensuel du savoir scientifique était facilitée par le développement d'une métaréflexion sur leurs propres productions de connaissance et les inévitables postulats et suppositions qui les fondent. Nous avons également pu observer qu'il découle de cette activité réflexive un modèle de science qui se distingue des modèles initialement tenus par les étudiants, par le pouvoir créateur et, surtout, le pouvoir de théoriser qu'il comporte: postuler, supposer, jauger collectivement de la plausibilité des résultats plutôt qu'en appeler à une instance occulte, voilà quelques-unes des conquêtes théoriques qu'ils ont effectuées et sur lesquelles nous allons nous attarder.
Sensorial, and more specifically, visual evidence is generally regarded by students as the basis for scientific knowledge: no need to postulate to understand, all is almost or practically given. From a science-teaching standpoint, this rather realistic approach is critical and leads to the belief that scientific concepts, laws, and theories stem from a world of materiality rather than from a world of models and relationships. During a 12-week study a group of 35 college students, we observed that for the majority of them, the development of metareflection on how they produce knowledge, with the inevitable and inherent postulates and conjecture, facilitated their understanding of the constructed and consensual character of scientific knowledge. We also observed that this reflexive activity facilitated the development of a new approach to science that differed from those models previously used by the students in its creative potential and, more importantly, in the power of its theoretics: to postulate, suppose, and collectively estimate the plausibility of results rather than calling up occult instances. These and other theoretical achievements will be discussed in this paper.
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17.
Drawing on self‐determination theory, a person‐centered methodology was adopted to identify distinct pupil profiles based on their psychological need satisfaction. A sample of 586 pupils (387 male, 199 female; mean age = 12.6, range 11–15 years old) from three secondary schools reported their psychological need satisfaction, and well‐ and ill‐being, with teachers rating pupil achievement. Hierarchical cluster analysis revealed five distinct profiles. Four profiles indicated synergy existed between the three needs, showing similar in‐group levels of satisfaction across the needs but in varying amounts. Univariate and multivariate analyses, controlling for school and taught subject, revealed the satisfied group displayed the highest classroom performance (F4,540 = 7.03; p < 0.001; ηp2 = 0.05), well‐being (F8,1,136 = 45.63; p < 0.001; Wilk's Λ = 0.57; ηp2 = 0.24) and lowest ill‐being (F8,1,134 = 23.39; p < 0.001; Wilk's Λ = 0.74, ηp2 = 0.14), whereas the dissatisfied group displayed the most adverse outcomes. The findings illustrate that the three psychological needs may operate interdependently and should be considered in combination rather than in isolation. The research offers practical insights into why pupils may function differently in classrooms and could inform targeted initiatives towards pupils with psychological need satisfaction deficits.  相似文献   

18.
INTRODUCTION One century ago, Hilbert announced his famous 23 problems. The Hilbert’s Fourth Problem is to characterize the (not-necessarily-reversible) distance functions on an open subset in ún such that straight lines are shortest paths. Distance functions induced by a Finsler metric are regarded as smooth ones. Thus Hilbert’s Fourth Problem in the smooth case is to characterize Finsler metric on an open subset in ún whose geodesics are straight lines. Finsler metric on an ope…  相似文献   

19.
The aim of this research is to characterize the development of fatigue damage by means of stress-strain hysteresis. Experiments were conducted on 14 specimens made of cold-finished unannealed AISI 1018 steel. Results demonstrate that the mechanical hysteresis loop areas, when plotted as a function of the number of loading cycles, show significant variations and demonstrate the three principal stages concerning the progress of the fatigue failure--initial accommodation, accretion of damage and terminal failure. These three stages of fatigue are marked by the transitions at cycles N2 and N3. Experimental results show that although fatigue life Nf ranges from 2644 cycles to 108 992 cycles, the ratios of N2/Nf and N3/Nf tend to be stable： N2/Nf=I 0.7%, N3/Nf=91.3%.  相似文献   

20.
Spatial ability (SA) is the cognitive capacity to understand and mentally manipulate concepts of objects, remembering relationships among their parts and those of their surroundings. Spatial ability provides a learning advantage in science and may be useful in anatomy and technical skills in health care. This study aimed to assess the relationship between SA and anatomy scores in first- and second-year medical students. The training sessions focused on the analysis of the spatial component of objects' structure and their interaction as applied to medicine; SA was tested using the Visualization of Rotation (ROT) test. The intervention group (n = 29) received training and their pre- and post-training scores for the SA tests were compared to a control group (n = 75). Both groups improved their mean scores in the follow-up SA test (P < 0.010). There was no significant difference in SA scores between the groups for either SA test (P = 0.31, P = 0.90). The SA scores for female students were significantly lower than for male students, both at baseline and follow-up (P < 0.010). Anatomy training and assessment were administered by the anatomy department of the medical school, and examination scores were not significantly different between the two groups post-intervention (P = 0.33). However, participants with scores in the bottom quartile for SA performed worse in the anatomy questions (P < 0.001). Spatial awareness training did not improve SA or anatomy scores; however, SA may identify students who may benefit from additional academic support.  相似文献   

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