共查询到20条相似文献，搜索用时 171 毫秒
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得到了二重随机序列{ξn,j;n,j≥1}随机和的重对数律,其中{ξn,j;n,j≥1}是相互独立的且对任意的正整数n,{ξn,j;j≥1}有相同分布. 相似文献
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假设{Zn;n=0,1,2,…}是一个随机环境中的分枝随机游动(即质点在产生后代的过程中,还作直线上随机游动),ξ={ξ0,ξ1,ξ2,…}为环境过程.记Z(n,x)为落在区间(-∞,x]中的第n代质点的个数,∫ξn(s)=∑∞j=o pξn(j)Sj为第n代个体的生成函数,mξn=∫1ξn(1).证明了在特定条件下,存在随机序列{tn}使得Z(n,tn)(∏n-1 i=0 mξi)-1均方收敛到一个随机变量.对于依赖于代的分枝随机游动,仍有类似的结论. 相似文献
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驱5千年迷雾现统治数学的集论百年病魔原形——破解2500年芝诺著名运动世界难题 总被引：4，自引：0，他引：4
正整数集{(1,2),(3,4),…}的各元能一一配对而无一"单身",而相应{1,(2,3),(4,5),…}中的1就只能"单身",除非拆散某"夫妻",故两者并非同一集而有"特异"集。医学不知血有血型就会医死人,数学不知集有奇、偶型之分就有中学数学重大错误:将两异集误为同一集而将部分误为全部等。使康脱误入百年歧途推出庞加莱认为是病魔的集论。据此证明了{1/2n}有末项,使2500年芝诺著名运动难题迎刃而解。 相似文献
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假如存在α>0使得n~(-α)q_n↓0,则称{q_n}为拟单调序列,简记为{q_n}∈QM,假如正数序列{l_n}满足l_(n+1)/l_n→1(n→∞),则称它为慢变化序列,若对上述l_n及某一α>0有q_n/n~αl_n↓0,则称{q_n}为正则拟单调序列,简记为{q_n}RQM,如果其中{l_n}满足条件n+1/l_n=1+O(1/n),则称q_n∈RQM,易见QM(?)RQM(?)RQM. 相似文献
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王志东 《内蒙古科技与经济》2002,(Z1)
1 数列极限的基本关系现行高级中学代数课本下册对数列的极限的定义是比较严格的 ,用了“ε- N”语言。该节的基本关系是 :1 .1 通过例子 0 .9,0 .99,0 .999,… 1 - 1 /1 0 n,…引入极限概念 ,给出定义。1 .2 利用定义研究例 1 {( - 1 ) n 1/n}、例 2 {n/( n 1 ) }、例 3{- 相似文献
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研究部分和Sn=∑k=1^nxk以及随机和SN（t）=∑k=1^N（t）xk的渐近估计,其中{XK,K≥1}为独立同分布（i．i．d）的非负随机变量序列,其共同的分布函数F属于次指数分布类,并且假设非负整值过程（N（t））t≥0与{XK,K≥1}相互独立。 相似文献
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探讨了索赔过程为多险种的风险模型,以及重尾随机变量分布函数f为OR类精确大偏差问题。假设一个保险公司有k种类型的险种．第i个险种的索赔过程记为｜xy,j≥1｜,i=1,…,k,在他人研究的基础上得出多险种风险模型s（k;n1,…,nk）=k∑i=1 ni∑j=1xy的精细大偏差． 相似文献
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F.M. Reza 《Journal of The Franklin Institute》1983,315(3):179-194
A basic theorem describing the convexity of the energy domain for the general family of linear time-invariant (active or passive, reciprocal or non-reciprocal, lumped or distributed, single variable or multivariable) physical system {T} is proved.Theorem: Let F = P + jQ represent the complex energy associated with any linear physical system T (n-port). For any specified excitation of frequency s and the family of constant energy content input signals {i:∥i∥= constant}, the point F describes a convex domain in the {P;Q} plane.Part I contains a mathematical and a network theoretic proof of the foregoing theorem. In Part II the geometric nature of the energy loci for the two-ports is examined. It is shown that for all two-ports with double eigenvalves the energy domain is circular. For two-ports with distinct eigenvalves, the convex energy domain is an ellipse. The geometric characterization of this elliptic domain is examined and examples verified by computer.The concept of convexity is frequently exploited in optimization of energy in electric power system and quadratic cost functions in control theory. In this respect the central theorem of this paper, its proof and geometric ramifications should prove to be of basic interest for all linear systems. 相似文献
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H.A. Chase 《Journal of The Franklin Institute》1982,313(2):61-71
Let Aχ = b be a linear system or equations in which A is an n × n matrix and both χ and b are n dimensional column vectors. If in addition A is row diagonally predominant (i.e. for any i, ¦:aii¦>¦:aij¦: for all 1?j?n,i≠j), then criteria are developed to show how to ascertain when such matrix problems may be successfully solved using Jacobi's iterative method. 相似文献
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Understanding the correlation between exposed surfaces and performances of controlled nanocatalysts can aid effective strategies to enhance electrocatalysis, but this is as yet unexplored for the nitrogen reduction reaction (NRR). Here, we first report controlled synthesis of well-defined Pt3Fe nanocrystals with tunable morphologies (nanocube, nanorod and nanowire) as ideal model electrocatalysts for investigating the NRR on different exposed facets. The detailed electrocatalytic studies reveal that the Pt3Fe nanocrystals exhibit shape-dependent NRR electrocatalysis. The optimized Pt3Fe nanowires bounded with high-index facets exhibit excellent selectivity (no N2H4 is detected), high activity with NH3 yield of 18.3 μg h−1 mg−1cat (0.52 μg h−1 cm−2ECSA; ECSA: electrochemical active surface area) and Faraday efficiency of 7.3% at −0.05 V versus reversible hydrogen electrode, outperforming the {200} facet-enclosed Pt3Fe nanocubes and {111} facet-enclosed Pt3Fe nanorods. They also show good stability with negligible activity change after five cycles. Density functional theory calculations reveal that, with high-indexed facet engineering, the Fe-3d band is an efficient d-d coupling correlation center for boosting the Pt 5d-electronic exchange and transfer activities towards the NRR. 相似文献
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Saika Manzoor Mohd A. Ganie Sabhiya Majid Iram Shabir Iram A. Kawa Qudsia Fatima Humira Jeelani Syed Douhath Yousuf Fouzia Rashid 《Indian journal of clinical biochemistry : IJCB》2021,36(3):278
Human polycystic ovary syndrome (PCOS)—a cluster of diseases displays various symptoms associated with endocrine and gynecological disorders in childbearing women. Oral contraceptive pills (OCP) being a drug of choice minimizes symptoms and complications associated with the disorder. But, the controversial data available in literature regarding use of OCPs compels us to setup a study design regarding effect of OCP treatment in PCOS subjects and the possible outcomes specifically regarding coagulation pathways. Two PCOS study groups have been selected according to Rotterdam Criteria: one with OCP treatment (n = 50) and other without any drug treatment i.e., drug naive (n = 50). Anthropometry, Biochemistry, Hormones, Insulin and various clotting factors like Factor XI, Factor V, tPA, TAT-III and D-dimer were analyzed in both groups. The results showed worsening of IR, Metabolic parameters and coagulopathy in OCP group comparative to drug naive group indicating adverse effects of the OCP treatment which puts these women at risk for number of future clinical implications especially Cardiovascular and metabolic complications. 相似文献
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具有重要战略地位的第三代移动通信核心技术研发面临着技术不确定、市场不确定的复杂创新环境,传统的线性创新模式已经无法适应急剧变革的创新活动要求。国内移动通信制造企业在已经取得产业核心技术标准重大突破的基础上,为推动中国3G标准成为主导标准,需要与有关各方密切合作,在技术、市场、开发、组织乃至制度环境等各个环节进行进一步的集成创新,确立我国在移动通信产业领域的竞争优势。 相似文献
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利用简单的手性有机配体L-酒石酸成功地合成出了一系列类似DNA螺旋构型的左、右旋的一维链状聚合物：{A[Mo2VIO4LnIII(H2O)6(C4H2O6)2]·4H2O}n (Ln = Sm, Eu, Gd, Ho, Yb, Y; C4H2O6 = L- 或 D-酒石酸； A = NH4 或 H3O)。通过水热法，巧妙地把传统的钼氧单核{MoO4}、双核{Mo2O7}以及{Mo8O26}等结构单元，通过有机配体配位的过渡金属单元交错地连接成零、一、二、三维的一系列结构新颖的化合物，这类化合物大多数具有可以容纳客体小分子的隧道或空穴，如 [Cu(4,4’-bpy)]2MoO4·2H2O，[Cu(4,4’-bpy)]2Mo2O7，[Cu(4,4’-bpy)(Hnic)(H2O)]2Mo8O26等。首次利用水热法合成出了含稀土的杂多酸类化合物，[Gd(H2O)3]3[GdMo12O42]·3H2O。该化合物是由Silverton-型的 [GdMo12O42]9- 阴离子和配位的Gd3+ 阳离子组成的。在[GdMo12O42]9- 离子中首次把顺磁性的钆(III)离子引入到该构型的中心，并且通过九配位的钆(III)离子把它们连接成具有介孔结构的三维网状化合物。该化合物的获得为今后合成类似化合物提供了一个很好的范例。在水热法合成出的化合物，[Cu2(C8H6N2)2(C7H6N2)]2[Mo8O26] 中，首次捕捉到喹喔啉的氧化产物苯并咪唑，证明了在水热条件下含氮的芳香杂环类的有机配体可以被二价铜氧化，其氧化产物进而作为配体直接与铜原子配位，最终形成新颖的上述化合物。 相似文献
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As customer co-creation behaviors in the peer-to-peer (P2P) economy become an increasingly important part of the global economy, the study of its drivers is of great necessity. One of the important yet overlooked drivers is digital physical attractiveness. This research draws on impression formation theory to examine how physical attractiveness drives customer citizenship behaviors in the P2P economy. More importantly, the current study investigates the non-linear effect of digital physical attractiveness and how the physical attractiveness effect differs across cultures. Two studies are used to test the framework. Study 1 uses secondary data crawled from China’s largest P2P accommodation-sharing platform. Study 2 analyzes the survey data from 533 accommodation-sharing customers in China (n = 213), Hungary (n = 159), and the U.S. (n = 161). Results found an n-shaped (inverted U) physical attractiveness effect in Study 1 in China, but a U-shaped effect in the cross-cultural context. The U-shaped effect is only effective when customers score high on collectivism, low on power distance, or low on masculinity. 相似文献
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The specific membrane capacitance (SMC) is an electrical parameter that correlates with both the electrical activity and morphology of the plasma membrane, which are physiological markers for cellular phenotype and health. We have developed a microfluidic device that enables impedance spectroscopy measurements of the SMC of single biological cells. Impedance spectra induced by single cells aspirated into the device are captured over a moderate frequency range (5 kHz–1 MHz). Maximum impedance sensitivity is achieved using a tapered microfluidic channel, which effectively routes electric fields across the cell membranes. The SMC is extracted by curve-fitting impedance spectra to an equivalent circuit model. From our measurement, acute myeloid leukemia (AML) cells are found to exhibit larger SMC values in hypertonic solutions as compared with those in isotonic solutions. In addition, AML cell phenotypes (AML2 and NB4) exhibiting varying metastatic potential yield distinct SMC values (AML2: 16.9 ± 1.9 mF/m2 (n = 23); NB4: 22.5 ± 4.7 mF/m2 (n = 23)). Three-dimensional finite element simulations of the microfluidic device confirm the feasibility of this approach. 相似文献
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根据熊彼特关于"创新是‘新的生产函数的建立’,即‘企业家对生产要素之新的整合’"这一经典定义,构建了创新绩效函数W_i=F_i(X_1,X_2,……X_n),其中(X_1,X_2,……X_n)为企业拥有的n个创新要素,W_i为创新绩效。本文研究(1)发现在创新绩效函数中,F_i为(X_1,X_2,……X_n)的整合方式,表示在企业各种创新要素保持不变的情况下,只对这些要素进行不同整合就会为企业带来不同创新绩效,而技术创新模式正是对创新要素进行整合的方式,因此F_i即是技术创新模式。(2)提出如何选择企业最优技术创新模式的原理,即在企业(X_1,X_2,……X_n)不变条件下,能为企业带来最大创新绩效W~*的技术创新模式,就是该企业最优技术创新模式F~*_i。由于F~*_i具体关系式不易清晰界定,故本文将F~*_i的求解过程视为一个黑箱,对其进行了整体拟合。(3)根据最优创新模式选择原理,在建立并评价X、Y、Z、W、F_i的基础上,构建了企业最优技术创新模式选择模型。(4)收集川酒企业样本数据,实证分析川酒企业最优技术创新模式选择过程。 相似文献