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1.
The sequences {Zi,n, l≤i≤n}, n≥l have multi-nomial distribution among i.i.d. random variables {X1,i, i≥1}, {X2,i,u≥l }, …, {Xm,i, i≥1 }. The extreme value distribution Gz(x) of this particular triangular array of i.i.d, random variables Z1,n, Z2Zn,n is discussed in this paper. We found a new type of not max-stable extreme value distributions, i) Gz(x) = r-1∏i=1ФAiαi(x) × Фαr (x);ii) Gz (x) = r-1∏i=1ψAiαi (x) × ψαr (x); iii) Gz (x) = r-1∏i=1 ∧Ai (λix) × A(x), r≥2, 0＜α1≤α2≤…≤αr and λi∈ (0,1] for i, l≤i≤r-1 which occur if Fj, …, Fm belong to the same MDA.  相似文献   

2.
In this work, we made progress on the problem that lr(○×)lp(○×)lq is a Banach algebra under schur product. Our results extend Tonge's results. We also obtained estimates for the norm of the random quadralinear form A:lMr×lNp×lKq×lHs→ C, defined by: A(ei, ej, ek, es)=aijks, where the (aijks)'s are uniformly bounded, independent, mean zero random variables. We proved that under some conditions lr(○×)lp(○×)lq (○×)ls is not a Banach algebra under schur product.  相似文献   

3.
Suppose {X, X n ;n≥1} is a sequence i.i.d.r.v. withEX=0 andEX 2<∞. Shao (1995) proved a conjecture of Révész (1990); ifP(X=±1)=1/2, then
. Furthermore he conjectured that
. In this paper we prove that if then this conjecture is ture. Project (10071072) supported by National Natural Science Foundation of China(NSFC).  相似文献   

4.
For an arbitrary subset P of the reals, a function f ： V →P is defined to be a P-dominating function of a graph G = （V, E） if the sum of its function values over any closed neighbourhood is at least 1. That is, for every v ∈ V, f（N[v]） ≥ 1. The definition of total P-dominating function is obtained by simply changing ‘closed＇ neighborhood N[v] in the definition of P-dominating function to ‘open＇ neighborhood N（v）. The （total） P-domination number of a graph G is defined to be the infimum of weight w（f） = ∑v ∈ V f（v） taken over all （total） P-dominating function f. Similarly, the P-edge and P-star dominating functions can be defined. In this paper we survey some recent progress on the topic of dominating functions in graph theory. Especially, we are interested in P-, P-edge and P-star dominating functions of graphs with integer values.  相似文献   

5.
The dilaton in Weyl-Scale induced gravitational theory is regarded as a candidate of dark energy. When the potential of dilaton field is taken as the form Wσ ＋ σ^2e^-βσ2, that there exist attractor solutions to the canonical dilatonic dark energy model and the phontam model, and these attractors correspond to an equation of state ω = -1 and a cosmic density parameter Ωσ = 1, which are important features for a dark energy model and can fit with the current observations. We find a sufficient condition of the existence of a late time de Sitter attractor. The attractor behaviors, the evolutions of the state parameter ω and the cosmic density parameter Ω, the evolution of X （σ/σ0） and Y （σ/σ0^2） with respect to N（ln a）are shown numerically.  相似文献   

6.
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   

7.
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   

8.
This study aimed at analysing traditionally taught children’s acquisition and use of shortcut strategies in the number domain 20–100. One-hundred-ninety-five second, third, and fourth graders of different mathematical achievement levels participated in the study. They were administered two tasks, both consisting of a series of two-digit additions and subtractions that maximally elicit the use of the compensation and indirect addition strategy (, so the answer is 2 + 1 or 3). In the first task, children were instructed to solve all items as accurately and as fast as possible with their preferred strategy. The second task was to generate at least two different strategies for each item. Results demonstrated that children of all grades and all achievement levels hardly applied the compensation and indirect addition strategy in the first task. Children’s strategy reports in the second task revealed that younger and lower achieving children did not apply these strategies because they did not (yet) discover these strategies. By contrast, older and higher achieving children appeared to have acquired these strategies by themselves. Results are interpreted in relation to cognitive psychological and socio-cultural perspectives on children’s mathematics learning.
Joke TorbeynsEmail:
  相似文献   

9.
Let Bnp={x ∈ Rn‖|x ‖p≤l} be the unit ball ofp norm in the n-dimensional normed space p. The formula for the volume of Bnp was obtained and its asymptotic properties were found out as n→∞and p→∞.  相似文献   

10.
The combination of online or semi-online with deterioration jobs has never been researched in scheduling problems. In this paper, two semi-online parallel machine scheduling problems with linear deterioration processing time are considered. In the first problem, it is assumed that the deterioration rates of jobs are known in an interval, that is, bj ∈[0, α], where 0 〈α≤ 1 and bj denotes the linear deterioration rate. In the second problem, it is assumed that the largest deterioration rate of jobs is known in advance, that is, b = max1≤j≤n {bj }. For each of the two problems, a heuristic MBLS algorithm is worked out and its worst-case ratio is analyzed. At the same time, the worst-case ratio of the list （LS） algorithm is investigated and it is proved that all the ratios are tight.  相似文献   

11.
The purpose of this research is to analyze the relationship between individual, institutional and demographic characteristics on one hand and the research productivity of agriculture faculty members on the other. The statistical population of the research comprises 280 academic staff in agricultural faculties all over Tehran Province. The data regarding research productivity and demographic characteristics were extracted from the faculty members’ profiles. Questionnaires were utilized to collect information concerning individual and institutional variables. The reliably of the questionnaire was calculated to be between 0.74 and 0.97 using the Cronbach’s Alpha. The regression analysis revealed that from among demographic characteristics two variables, namely, academic rank and age ( \textR\textAD 2 {\text{R}}_{\text{AD}}^{ 2}  = 0.265), among individual characteristics, three variables, namely, working habits, creativity as well as autonomy and commitment ( \textR\textAD 2 {\text{R}}_{\text{AD}}^{ 2}  = 0.097), and among institutional characteristics four variables namely, network of communication with colleagues, resources of facilities, corporate management and clear research objectives ( \textR\textAD 2 {\text{R}}_{\text{AD}}^{ 2}  = 0.151) were significant predictors for agricultural faculty members’ research productivity.  相似文献   

12.
Acoustic wave propagation in piezoelectric crystals of classes?43m and 23 is studied. The crystals Tl3VS4 and Tl3TaSe4 (43m) of the Chalcogenide family and the crystal Bi12TiO20 (23) possess strong piezoelectric effect. Because the surface Bleustein-Gulyaev waves cannot exist in piezoelectric cubic crystals, it was concluded that new solutions for shear-horizontal surface acoustic waves (SH-SAWs) are found in the monocrystals using different electrical boundary conditions such as electri- cally “short” and “open” free-surfaces for the unique [101] direction of wave propagation. For the crystal Tl3TaSe4 with coefficient of electromechanical coupling (CEMC) Ke2=e2/(C×g)～1/3, the phase velocity Vph for the new SH-SAWs can be calculated with the following formula: Vph=(Va Vt)/2, where Vt is the speed of bulk SH-wave, Vt=Vt4(1 Ke2)1/2, Va=aKVt4, aK=2[Ke(1 Ke2)1/2-Ke2]1/2, and Vt4=(C44/ρ)1/2. It was found that the CEMC K2 evaluation for Tl3TaSe4 gave the value of K2=2(Vf–Vm)/Vf～0.047 (～4.7%), where Vf～848 m/s and Vm~828 m/s are the new-SAW velocities for the free and metallized surfaces, respectively. This high value of K2(Tl3TaSe4) is significantly greater than K2(Tl3VS4)～3% and about five times that of K2(Bi12TiO20).  相似文献   

13.
In this classroom article, we present a geometrical interpretation of a well-known inequality \(\frac{x}{1+x} < {ln}(1+x) < {x}-\frac{x^2}{2(1+x)}\) for x > 0.  相似文献   

14.
1　Introduction　Ahugeamountofliteratureexistsonthestudyofi dentifyingtracemetalionsbymeansofspectropho tometry[1 3] ,fluorimetry[4 6 ] aswellas polarogra phy[7 9] ,whichhaveactiononlocatingtheendpointoftheindicatingreaction .Howeverbothspectropho tometryandfluorimetryareeasytobeinterferedbycolororprecipitation ,whilepolarographyhasanissueofmercurypollution .Thecatalyzingkineticanalysishasthecharacteristicsofhighsensitivityandspeedi ness.Oscillographicpotentiometryisasimpleintu itionisticanal…  相似文献   

15.
An extension of the Lie algebra An-1 has been proposed [ Phys. Lett. A, 2003, 310 : 19-24 ]. In this paper, the new Lie algebra was used to construct a new higher dimensional loop algebra G^～. Based on the loop algebra G^～, the integrable couplings system of the NLS-MKdV equations hierarchy was obtained. As its reduction case, generalized nonlinear NLS-MKdV equations were obtained. The method proposed in this letter can be applied to other hierarchies of evolution equations.  相似文献   

16.
In this paper, the author proposes a new virtual topology, referred to as fully connected cubic network (FCCN), for the wavelength division multiplexing (WDM) multihop lightwave network. The FCCN is a multi-level, highly scalable and modular architecture. Anm level FCCN is constructed by “fully connecting” 8 (m−1)-FCCNs. The FCCN satisfies very well all the design requirements for WDM lightwave networks. The nodal degree is no more than four, and independent of the network size. Both the diameter and the average hop distance are in the order of . Owing to the highly scalable structure, the routing algorithm proposed in this paper is very simple to implement. Wavelengths reuse technique can be applied with high efficiency to FCCN. Project supported by Zhejiang University Cao Guangbiao Technology Development Funding(413C01302*29808)  相似文献   

17.
The need to enhance students’ learning outcomes has become integral in secondary schools in developing countries due to increased students enrollment. Research has shown that the strategies utilized in teaching secondary school students have significant influence on their learning outcomes. At present in Nigeria, public secondary schools have not been deploying learning technologies to teach students despite the surge in enrollment. This study, therefore, determined the effects of computer-aided and blended teaching strategies on students’ achievement in civic education concepts in mountain learning ecologies. The study adopted the pretest-posttest, control group, quasi-experimental design using 3 × 2 × 3 factorial matrix. Seventy-eight students from six intact classes in secondary schools in Ondo State were selected for the study and randomly assigned to experimental and control groups. Five instruments used were: Students’ Knowledge of Civic Education Test (r = 0.78), Academic Ability Test (r = 0.72), Online and Blended Teaching Instructional Guides for experimental groups, Conventional Lecture Method Guide for the control group and Teaching Strategies Evaluation Sheet. One hypothesis was tested at 0.05 level of significance. Data was subjected to Analysis of Covariance, Estimated Marginal Means, and Scheffe’s Pairwise Comparison. There was a significant effect of treatment on students’ achievement in Civic Education concepts (F (2; 61) = 4.93, p < 0.05; η 2  = .14). The students exposed to Computer-aided teaching programme had higher adjusted achievement mean score (\( \overline{x} \)= 27.86), than the blended instructional strategy group (\( \overline{x} \)= 23.06), and the control group (\( \overline{x} \)= 18.69). It was, therefore, recommended that teachers in secondary schools in mountainous locations should explore the benefits of teaching with Information and Communication Technology based strategies in civic education classrooms.  相似文献   

18.
Research often reports an overt discrepancy between theoretically/out-of context expressed teacher beliefs about mathematics and pedagogy and actual practice. In order to explore teacher knowledge in situation-specific contexts we have engaged mathematics teachers with classroom scenarios (Tasks) which: are hypothetical but grounded on learning and teaching issues that previous research and experience have highlighted as seminal; are likely to occur in actual practice; have purpose and utility; and, can be used both in (pre- and in-service) teacher education and research through generating access to teachers’ views and intended practices. The Tasks have the following structure: reflecting upon the learning objectives within a mathematical problem (and solving it); examining a flawed (fictional) student solution; and, describing, in writing, feedback to the student. Here we draw on the written responses to one Task (which involved reflecting on solutions of $ {\left| x \right|} + {\left| {x - 1} \right|} = 0 $ ) of 53 Greek in-service mathematics teachers in order to demonstrate the range of teacher knowledge (mathematical, didactical and pedagogical) that engagement with these tasks allows us to explore.  相似文献   

19.
The report is a translation of part of a Swedish paper entitled “On Students' Achievement in Mathematics after Finishing Comprehensive School”. The intention of the investigation was to

  • - diagnose the retention of some basic skills in some topics in algebra and geometry,
  • - reveal difficult steps in the learning processes in these topics.
    • Starting with a complicated question, e.g. the equation \(\frac{{3x - 2}}{2} = \frac{x}{3}\) a sequence consisting of 5–15 problems were constructed. Each new problem followed by the preceding one by taking away one or two details. \(\begin{gathered} 3(3x - 2) = 2x \\ {\text{ 9}}x - 6 = 2x \\ {\text{ 7}}x - 6 = 0 \\ {\text{ 7}}x = 6 \\ \end{gathered} \) is an example of a sequence belonging to the equation above. From about 10 complicated problems (“top-items”) and their sequences, in all 130 items, 10 sub-tests were put together in such a way that the pupils who took the test were not aware of the sequences but found no connection between the problems. Many surprising results were found, e.g., that the students scored higher on 14/(x+2)=2 than on 4/x=3, that the difficulty in finding the area of a triangle depended on the position of the triangle and that the problems “Simplify a/a 2, a2/a, a/a” were of quite unequal difficulty. A discussion about the students' thinking in patterns and mechanically learning ends the report.  相似文献   

    20.
    １ＩｎｔｒｏｄｕｃｔｉｏｎＤｉｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓｗｉｔｈｔｕｒｎｉｎｇｐｏｉｎｔｓｅｘｉｓｔｗｉｄｅｌｙｉｎｍａｎｙｐｒｏｂｌｅｍｓｏｆｍａｔｈｅｍａｔｉｃｓｐｈｙｓｉｃｓ,ｓｏｔｈｅｓｅｐｒｏｂｌｅｍｓａｒｅｖｅｒｙｉｍｐｏｒｔａ...  相似文献   

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