共查询到20条相似文献，搜索用时 46 毫秒
1.
本文给出了交错幂数列 ∑nk=0( - 1) k∏st=1(α+ βtk+… +γtkl) pt [α ,βt,γt( 1 t s) 为任意的实数或复数 ,Pi(1 i s)是一组给定的正整数列 ]的求和问题 ,推广了文献 [1 ]中的结果 相似文献
2.
The authors present their analysis of the differential equation dX(t)/dt=AX(t)-XT(t)BX(t)X(t), where A is an unsymmetrical real matrix, B is a positive definite symmetric real matrix, X∈Rn; showing that the equation characterizes a class of continuous type full-feedback artificial neural network; We give the analytic expression of the solution; discuss its asymptotic behavior; and finally present the result showing that, in almost all cases, one and only one of following cases is true. 1. For any initial value X0∈Rn, the solution approximates asymptotically to zero vector. In this case, the real part of each eigenvalue of A is non-positive. 2. For any initial value X0 outside a proper subspace of Rn, the solution approximates asymptotically to a nontrivial constant vector (X0). In this case, the eigenvalue of A with maximal real part is the positive number λ=‖(X0)‖2B and (X0) is the corresponding eigenvector. 3. For any initial value X0 outside a proper subspace of Rn, the solution approximates asymptotically to a non-constant periodic function (X0,t). Then the eigenvalues of A with maximal real part is a pair of conjugate complex numbers which can be computed. 相似文献
3.
Two experiments demonstrate that 5‐month‐olds are sensitive to local redundancy in visual‐temporal sequences. In Experiment 1, 20 infants saw 2 separate sequences of looming colored shapes that possessed the same elements but contrasting transitional probabilities. One sequence was random whereas the other was based on bigrams. Without any prior exposure, infants looked longer at the random sequence. In Experiment 2, 17 infants looked equally long at bigram‐ and trigram‐based sequences. However, an analysis of local redundancy revealed that in both experiments disengagement from the sequences was governed by local repetitions rather than by global sequence statistics. This finding suggests that a spontaneous sensitivity to stimulus complexity helps orient infants to sequences they can learn from. 相似文献
4.
考虑了多元t-copula的上尾象限相依指数和上尾极值相依指数,该t-copula是在相依结构下定义的．由于多元连续型随机变量的copula函数关于严格单调递增变换具有不变性质,由此推导了多元t-copula的尾相依指数的精确表达式,得到的结果明显比以往文献给出的结论更加简洁．然后,讨论了这2个相依指数关于相关系数的局部单调性质：上尾极值相依指数关于相关系数是严格单调递增的,但上尾象限相依指数的单调性比较复杂．通过蒙特卡罗模拟数据验证了结果的正确性．同时,发现所有结论可以推广到生成随机变量是正则变化的分布类中． 相似文献
5.
利用重合度理论中的延拓定理,证明了非线性脉冲泛函微分方程y″(t)+g(t,y(t-τ(t)))=p(t),t≠τk周期解的存在性. 相似文献
6.
Kinetic contours in infants' visual perception 总被引：2，自引：0，他引：2
3-month-old infants' perception of "camouflaged" forms that are only visible when moving was studied. Displays were used in which figure and ground had an identical random dot texture, and no edge indicated the form of the figure. The form was invisible when stationary. Discrimination of 2 different forms was tested (a) when the forms were visible only through motion, and (b) when the forms appeared as stationary white figures on black ground. The babies discriminated the forms in both conditions. Furthermore, when infants were habituated to one of the moving forms and subsequently presented with the same and a new static form, they looked longer at the new form. This indicates that they recognized the static form as either the same or different from the moving form seen before, although the optical sources of information were completely different. At 3 months, infants can therefore effectively use kinetic information to organize the visual input in higher-order structures. 相似文献
7.
横田浩一 《韩山师范学院学报》2012,(1):8-14
近年来,关于中国华南的族群研究已经不少。但是,有关潮汕地区的族群研究成果却是不多。因此,该文试图对潮汕地区的族群情况问题进行探讨。在饶平县X村,开基祖从海南岛移民到那里的时候,将入赘风俗作为移民的依据,这些习俗在华南地区是比较普遍的现象,所以入赘风俗本身不是问题。笔者所提到的问题就是在清代他们形成宗族组织的时候,X村的人们通过入赘风俗的文化实践,特别是族谱的编者重新贴上自己的来历是外来人的族群标签,才能够主张和证明自己的文化正统性。 相似文献
8.
本文讨论了独立随机变量之和的绝对中心矩的几个性质,其中包括E｜（X＋Y）-E（X＋Y）｜-E｜（X-Y）-E（X-Y）｜的表达式,这里X和Y是相对独立的随机变量. 相似文献
9.
我们在使用＂前/后X＂来指示时间时,发现＂前/后X＂存在多种意义。本文首先分析了＂前/后X＂在指示时间时所存在的几种形式,然后分析了产生这几种形式的原因,最后把＂前/后X＂与＂X前/后＂作了对比,认为它们本是不相关的两组时间指示词,但是由于一定条件的存在,它们还是能够互换的。 相似文献
10.
假设X是一实Banach空间,T：T→X是一致伪压缩映射,在一定的条件下,证明了具随机误差的Mann迭代过程强收敛T的不动点,并且相对于T是几乎稳定的．同时得到相关结果,具随机误差的Mann迭代过程强收敛于一致增生映射的非线性方程的解,并且是几乎稳定的． 相似文献
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12.
陈玉成 《鹭江职业大学学报》2014,(5):98-101
研究序列{Xn},{Xn}满足Xn = Yn（mod 2）,其中Yn∈Z＋, Y0≥2, Yn＋1= Yn ＋[Yn/2],证明了{Xn}为一独立随机变量序列,并且是一时间齐次Markov链。最后,利用该Markov链{Xn}的性质,证明了入圈问题经过有限次插点, Cm 的任意一边上都至少插入一个新点。 相似文献
13.
Conventional scan-to-scan integration correlation （SIC） algorithms can detect small and stationary targets. However, they are ineffective in detecting small and fast-moving targets. This paper presents an improved SIC algorithm together with clutter suppression measures that remove or decrease sea clutter. The algorithm divides the scan-to-scan integration （SI） into two branches, one provides optimum clutter attenuation by means of SI weighting while the other ensures that targets are detected even if they are fast-moving. Sea clutter suppression can lower detection thre-sholds and, at the same time, increase signal-to-clutter ratio. Simulation results show that the proposed approach greatly improves the detection capability for warship radar. 相似文献
14.
A （t, n） threshold signature scheme distributes the secret key and hence the signing ability to n players in a way that any set of t＋ 1 or more honest players can collaborate to sign, while any set of t players cannot. In this paper we propose an identity-based threshold signature （IBTHS） scheme from bilinear pairings. The signing phase of our scheme is non-interactive, meaning that the signing players do not need to talk to each other. We prove our scheme secure （i.e., unforgeable and robust） in the standard model （i.e., without random oracles）. No earlier proposed IBTHS scheme achieved even one of the features of being non-interactive （in the signing phase） and secure in the standard model. 相似文献
15.
耿佳 《青海师范大学学报(哲学社会科学版)》2012,34(4):43-47
在追求法制化的进程中,国家制定法虽然日益完备,但是“法典不可能没有缝隙”,法律漏洞是客观存在的.在待决的具体案件中,法官在制定法的范围内未能找到可适用的依据时,法官由于“不得拒绝裁判”义务的存在,必须运用一定的方法填补法律漏洞.本文认为习惯法是从人们普遍遵从的生产生活的习惯中衍化而来且对人们的行为有一定的指引、规范和评价作用,并且中国作为传统的“礼俗”社会,在填补法律漏洞的司法实践过程中,习惯法作为一种本土资源不容忽视. 相似文献
16.
对2列非负带有次指数分布的独立同分布随机变量的差,以及随机脚标为负相协随机变量生成的严平稳更新记数过程进行了探讨.利用修正的随机变量部分和的精致大偏差结果及关于负相协随机变量的基本更新定理和中心极限定理,得到了随机变量列差的随机和的精致大偏差.考虑了基于顾客来到过程的保险风险模型,利用随机和的精致大偏差结果,得到了当顾客数或者时间趋于无穷时,保险公司破产概率的一致渐近性. 相似文献
17.
This study examines how high school students use diagrams and summaries during reading and the effects of such on comprehension. The roles of verbal and spatial ability are also examined. Seventy-four Year 7 (13-year-old) students each read a text presented on a computer screen. The text was presented one sentence at a time and subjects could call up a diagram or content-equivalent summary of the main ideas of the text at any time. Time to read the sentences and the adjunct aids was controlled by the subject and recorded by the computer. In addition, the computer kept a record of where in the text subjects made a text-to-aid move. After reading, the subjects completed a 10-minute filler task and then produced free recalls of the text. The free recalls were examined for the inclusion of details and main ideas. Path analyses showed a significant direct effect of verbal ability on the recall of details and main ideas as well as a significant indirect effect through time on diagram. Spatial ability was not found to have any effect on recall, either directly or indirectly. Analyses of text-to-diagram moves showed more inspections in the first few sentences followed by an essentially random inspection pattern. Instructional implications are discussed. 相似文献
18.
在我国现行行政体制下，省(自治区、直辖市)、县(市、区)及乡镇三级政权通常被列入地方政府的范畴。它们在社会政治经济生活中扮演着管理国家事务、组织社会经济和文化建设、维护社会公共秩序等重要角色，对辖区公民承担着广泛的受托责任．负责向全体公众提供安全保障、休闲娱乐、文化教育、医疗保健等方面的”公共物品”和”准公共物品”。各级地方政府在向辖区的公民和社会公众提供”公共物品”和”准公共物品”的过程中，必然会耗费一定的人力、物力、财力。这些人、财、物的耗费的货币表现，即构成地方政府的行政运行成本。地方政府的行政运行成本具体可以分为人力成本、公务成本和设施成本三种形式，具有鲜明的个性特征、受多种因素的制约和影响。对地方政府行政运行成本进行全面、深入、系统的研究具有十分重要的现时意义。 相似文献
19.
Judy Kalman 《International journal of qualitative studies in education》2013,26(3):187-203
In Mexico City there is a system of public scribes who function as written language brokers, composing letters, filling out forms, drawing up contracts, designing invitations or producing any other kind of written product that a client might require. The main question to be addressed in this paper is how the scribes learned their trade, and how they acquired the literacy practices and knowledge they need to make a living writing for others. The scribes' views about what they needed to learn and how they went about learning it is of interest to researchers and practitioners alike. Of particular relevance is the relationship they establish between the specific context in which they write and the use of ''local knowledge'' (as defined by Geertz) while writing. Their commentary on what they learned to do at school, what they learned to do in order to meet the demands of their clients, and how they must meet those demands is of particular interest at a time when educators are broadening their views about literacy, how it is learned, and how it is accomplished. 相似文献
20.
XA型生物性别决定机制的特点:蚜虫的X染色体含X基因的数量小于常染色体组合的Y基因,为0.6-0.8;蝗虫的X染色体与常染色体含X基因与Y基因的数量相同,为1.0;X染色体含的X基因全都能在性别决定中起作用,会是有效性基因;常染色体组则随各种性型的X染色体与常染色体组的数量关系不同,所含的Y基因有的在性别决定中起作用,有的在性别决定中不起作用,有有效性基因和无效性基因之别。由此,决定了蚜虫须经历有性和无性两个世代,以有性和无性两种生殖来完成世代交替,靠营群居生活才能进行繁衍生息;蝗虫不再须经历有性有无性两个世代,只以有性生殖来完成世代交替,营独栖生活也能进行繁衍生自。 相似文献