有向线图中的(k,l)-核     

鲁勤  单而芳  赵敏 《上海大学学报(英文版)》2006,10(6):484-486

1 Introduction We consider the finite digraphs that do not havemultiple arcs or loops , but pairs of opposite arcs areallowed.LetD=(V,A) be a digraph , whereVisthe set of vertices andAis the set of arcs .If there isan arc (x,y) fromxtoy,thenthe vertexxis …  相似文献   

Pigeons’ memory for time: Assessment of the role of subjective shortening in the duration-comparison procedure     

Patrick Van Rooyen  Angelo Santi 《Learning & behavior》2009,37(1):74-84

Pigeons were trained in a duration-comparison procedure to peck one key if the comparison duration (c) was 1 sec shorter than a standard duration (s), and another key if c was 1 sec longer than s. During training, the s-c delay was 1 sec, and the total duration of an s-c pair was not predictive of the correct choice. In Experiment 1, during equal-duration pair test trials, pigeons increasingly responded long (i.e., c τ s) as the s-c delay was lengthened. In Experiment 2, we demonstrated that s affected long responding on equal-duration test trials, even at the 8-sec s-c delay. In Experiment 3, long responding increased as the s-c delay was lengthened, even when stimulus conditions during the s-c delay differed from those during the intertrial interval (ITI). Additional analyses indicated that it was unlikely that the increase in long responding was due to the pigeons’ adding the s-c delay to c and comparing the total against the duration of s. The increase in long responding with an increase in s-c delay is more consistent with subjective shortening of s than with confusion between the s-c delay and the ITI.  相似文献   

Projectively flat exponential Finsler metric     

YU Yao-yong YOU Ying 《浙江大学学报(A卷英文版)》2006,7(6):1068-1076

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   

A Comparison of Item Fit Statistics for Mixed IRT Models     

Kyong Hee Chon  Won-Chan Lee  Stephen B. Dunbar 《Journal of Educational Measurement》2010,47(3):318-338

In this study we examined procedures for assessing model-data fit of item response theory (IRT) models for mixed format data. The model fit indices used in this study include PARSCALE's G² , Orlando and Thissen's S − X² and S − G² , and Stone's χ²* and G²* . To investigate the relative performance of the fit statistics at the item level, we conducted two simulation studies: Type I error and power studies. We evaluated the performance of the item fit indices for various conditions of test length, sample size, and IRT models. Among the competing measures, the summed score-based indices S − X² and S − G² were found to be the sensible and efficient choice for assessing model fit for mixed format data. These indices performed well, particularly with short tests. The pseudo-observed score indices, χ²* and G²* , showed inflated Type I error rates in some simulation conditions. Consistent with the findings of current literature, the PARSCALE's G² index was rarely useful, although it provided reasonable results for long tests.  相似文献   

Projectively flat Asanov Finsler metric     

HAN Jing-wei YU Yao-yong 《浙江大学学报(A卷英文版)》2007,8(6):963-968

In this work, we study the Asanov Finsler metric F=α(β2/α2 gβ/α 1)1/2exp{(G/2)arctan[β/(hα) G/2]}, where α=(αijyiyj)1/2 is a Riemannian metric and β=biyj is a 1-form, g∈(-2,2), h=(1-g2/4)1/2, G=g/h. We give the necessary and sufficient condition for Asanov metric to be locally projectively flat, i.e., α is projectively flat and β is parallel with respect to α. Moreover, we proved that the Douglas tensor of Asanov Finsler metric vanishes if and only if β is parallel with respect to α.  相似文献   

IDENTIFICATION AND ASSESSMENT OF TAIWANESE CHILDREN’S CONCEPTIONS OF LEARNING MATHEMATICS     

Mei-Shiu Chiu 《International Journal of Science and Mathematics Education》2012,10(1):163-191

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   

A general version of the Morse-Sard theorem     

姜海益 《浙江大学学报(A卷英文版)》2004,5(7):754-758

Let k,m,n be positive integers,and k≥2,α∈(0,1],0＜r＜min {m,n} an integer,d=r (m-r)/(k α),and iff∈ Ck,α(Rm,R″),A =Cr(f)= {x ∈ Rm ,rank(Df(x))≤r},thenf(A)is d-null.Thus the statement posed by Arthur Sard in 1965 can be completely solved when k≥2.  相似文献   

Results on energies for trees with a given diameter having perfect matching     

王文环  康丽英 《上海大学学报(英文版)》2011,15(6):493-500

Let Γd2nbe the set of trees with a given diameter d having a perfect matching,where 2n is the number of vertex.For a tree T in Γd2n,let Pd+1be a diameter of T and q = d m,where m is the number of the edges of perfect matching inPd+1.It can be found that the trees with minimal energy in Γd2nfor four cases q = d 2,d 3,d 4,[d2],and two remarks aregiven about the trees with minimal energy in Γd2nfor2d 33q d 5 and [d2] + 1 q2d 33 1.  相似文献   

Generalized Derivations in Prime Rings     

吴伟  宛昭勋 《天津大学学报(英文版)》2011,17(1):75-78

Let R be a ring, a ,b ∈ R, ( D , α ) and (G , β ) be two generalized derivations of R . It is proved that if aD ( x ) = G ( x )b for all x ∈ R, then one of the following possibilities holds: (i) If either a or b is contained in C , then α = β= 0 and there exist p , q ∈ Qr ( RC) such that D ( x )= px and G ( x )= qx for all x ∈ R;(ii) If both a and b are contained in C , then either a = b= 0 or D and G are C-linearly dependent;(iii) If neither a nor b is contained in C , then there exist p , q ∈ Qr ( RC) and w ∈ Qr ( R) such that α ( x ) = [ q ,x] and β ( x ) = [ x ,p] for all x ∈ R, whence D ( x )= wx-xq and G ( x )= xp + avx with v ∈ C and aw-pb= 0.  相似文献   

L^p-estimates on a ratio involving a Bessel process     

LU Li-gang YAN Li-tan XIANG Li-chi 《浙江大学学报(A卷英文版)》2007,8(1):158-163

INTRODUCTION Throughout this paper, we shall work with a filtered complete probability space (?,F,(Ft),P) sat-isfying the usual conditions. Let B=(Bt)t≥0 be a stan-dard Brownian motion with B0=0. Denote by ú the set of all non-negative real numbers. Recall that a diffusion process X starting at x≥0 is called the square of a Bessel process of dimension δ>0 if d X t = δd t 2 | X t |d Bt , X 0= x, (1) Clearly, this equation has a unique non-negative strong solution X, i.e., …  相似文献   

A rigidity theorem for submanifolds in S^n＋p with constant scalar curvature     

张剑锋 《浙江大学学报(A卷英文版)》2005,6(4):322-328

Let M‘ be a closed submanifold isometrically immersed in a unit sphere S^n p. Denote by R, H and S, the normalized scalar curvature, the mean curvature, and the square of the length of the second fundamental form of M‘, respectively. Suppose R is constant and ≥1. We study the pinching problem on S and prove a rigidity theorem for M‘ immersed in S^n p with parallel normalized mean curvature vector field. When n≥8 or, n=7 and p≤2, the pinching constant is best.  相似文献   

Estimation method for mixed-effect coefficient semiparametric regression model     

Pan Jian-min 《浙江大学学报(A卷英文版)》2000,1(1):71-77

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   

Metaphorical images of schooling: beliefs about teaching and learning among prospective teachers from the United States displaying different motivational profiles     

Margareta Maria Thomson 《教育心理学》2016,36(3):502-525

This study focused on investigating the types of schooling beliefs (teaching and learning) expressed through metaphorical images by prospective teachers (PTs) from the United States. Participants (N = 215) rated 10 schooling metaphors illustrating the student–school–teacher relationships (i.e. Passenger–Bus–Driver; Student is a passenger, School is a bus and Teacher is a driver). Two main factors, a student-centred and a teacher-centred approach described the key schooling beliefs of PTs. Additionally, differences in PTs’ schooling beliefs across typologies/clusters of PTs were found. Further, qualitative data from interviews illustrated how each cluster specifically expressed their instructional views.  相似文献   

Precise asymptotics in the law of the logarithm for random fields in Hilbert space     

FU Ke-ang  ZHANG Li-xin 《浙江大学学报(A卷英文版)》2007,8(4):651-659

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   

Book reviews     

《Literacy》1984,18(3):184-190

Books reviewed in this article: Chambers, Aidan. Introducing Books to Children Celebrating Eid — A Resources Pack, The Multicultural Support Service. Pugh, A. K. and J. M. Ulijn (Ed.) Reading for Professional Purposes: Studies and Practices in Native and Foreign Languages Scottish Primary Mathematics Group. Primary Mathematics: A Development through Activity Lambert, David. The Seasons Grunsell, Angela (Consultant). On the Moon Anderton, Alain. Money Matters Kroll, Barry M. & Wells, Gordon (Ed.). Explorations in the Development of Writing Granny's Garden Sentence Sequencing Tree of Knowledge  相似文献   

Editorial Review and Book Reviews     

《The International Journal of Art & Design Education》1997,16(1):91-101

McGeoch, B. And Porch, S Looking at Scottish Art Malcolm Dickson (editor) Art with People Hugh Ferguson Glasgow School of Art - The History Alan Crawford Charles Rennie Mackintosh Wendy Kaplan (editor) Charles Rennie Mackintosh Pamela Robertson Charles Rennie Mackintosh: Art is the Flower Janice Helland The Studios of Frances and Margaret Macdonald Architecture on Disc, Glasgow, 1995 Glasgow-on-Disc Prairie Multimedia Inc., Chicago, 1995 Frank Lloyd Wright Companion  相似文献   

Assessing Students' Understandings of Biological Models and their Use in Science to Evaluate a Theoretical Framework     

Juliane Grünkorn  Annette Upmeier zu Belzen  Dirk Krüger 《International Journal of Science Education》2013,35(10):1651-1684

Research in the field of students’ understandings of models and their use in science describes different frameworks concerning these understandings. Currently, there is no conjoint framework that combines these structures and so far, no investigation has focused on whether it reflects students' understandings sufficiently (empirical evaluation). Therefore, the purpose of this article is to present the results of an empirical evaluation of a conjoint theoretical framework. The theoretical framework integrates relevant research findings and comprises five aspects which are subdivided into three levels each: nature of models, multiple models, purpose of models, testing, and changing models. The study was conducted with a sample of 1,177 seventh to tenth graders (aged 11–19 years) using open-ended items. The data were analysed by identifying students' understandings of models (nature of models and multiple models) and their use in science (purpose of models, testing, and changing models), and comparing as well as assigning them to the content of the theoretical framework. A comprehensive category system of students' understandings was thus developed. Regarding the empirical evaluation, the students' understandings of the nature and the purpose of models were sufficiently described by the theoretical framework. Concerning the understandings of multiple, testing, and changing models, additional initial understandings (only one model possible, no testing of models, and no change of models) need to be considered. This conjoint and now empirically tested framework for students' understandings can provide a common basis for future science education research. Furthermore, evidence-based indications can be provided for teachers and their instructional practice.  相似文献   

Editorial Review and Book Reviews     

Richard Yeomans 《The International Journal of Art & Design Education》1998,17(3):323-332

Mervyn Romans, Basic Design: The Dynamics of Visual Form Louise Campbell, Carl and Karin Larsson: Creators of the Swedish Style Jewellery and Adornment: Information and Ideas for Teachers Constable: Information and Ideas for Teachers Drawing in Museums: Information and Ideas for Teachers Sculpture at the V&A: A Handbook for Teachers The Renaissance at the V&A: A Handbook for Teachers The 20th Century: A Teacher’s Guide Looking into The Tate: Exciting Ways to Explore the Tate Gallery’s Collection The Pre-Raphaelites and their World Movements in Modern Art Modernism Realism Surrealism Howard Hollands, Minimalism Penny Hay, Art, Craft and Design. A Practical Guide for Teachers Key Stages I & 2 Richard Yeomans, The Mosque and the Modern World: Architects Patrons and Design since the 1950s  相似文献   

组成于平行机和批处理机的二阶段混合流水作业问题     

何龙敏  孙世杰 《上海大学学报(英文版)》2007,11(1):33-33

A hybrid two-stage flowshop scheduling problem was considered which involves m identical parallel machines at Stage 1 and a burn-in processor M at Stage 2, and the makespan was taken as the minimization objective. This scheduling problem is NP-hard in general. We divide it into eight subcases. Except for the following two subcases： （1） b≥ an, max{m, B} 〈 n; （2） a1 ≤ b ≤ an, m ≤ B 〈 n, for all other subcases, their NP-hardness was proved or pointed out, corresponding approximation algorithms were conducted and their worst-case performances were estimated. In all these approximation algorithms, the Multifit and PTAS algorithms were respectively used, as the jobs were scheduled in m identical parallel machines.  相似文献   

The generative paradigm     

Chris Loynes 《Journal of Adventure Education & Outdoor Learning》2013,13(2):113-125

This research highlights the learning of female offenders on a 20-day tailor-made experiential adventure education course (Women in Action) delivered by Outward Bound New Zealand. The aims of the course were to increase self-awareness, to develop an understanding of the concept of choice and self responsibility, to improve communication skills and to effectively influence others. Twenty-seven women were interviewed immediately after the course and 14 of these, three months post-course. Most women indicated that their self-confidence had increased and they had become more self-aware. Key factors in facilitating learning opportunities for the women were the instructors and the course environment both physical and social. The holistic course approach provided physical, creative, emotional and reflective opportunities, enabling all the women to develop personally. The challenge of applying their learning on return to prison was highlighted by some participants.