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141.
At each time be a random sequence of non-negative numbers that are ultimately zero in a random environment . The existence and uniqueness of the nonnegative fixed points of the associated smoothing transformation in random environment are considered. These fixed points are solutions to the distributional equation for ,where are random variables in random environment which satisfy that for any environment ; under ; are independent of each other and , and have the same conditional distribution where T is the shift operator. This extends the classical results of J. D. Biggins [J. Appl. Probab., 1977, 14: 25-37] to the random environment case. As an application, the martingale convergence of the branching random walk in random environment is given as well. 相似文献
142.
鲍根德 《中国科学B辑(英文版)》1989,(11)
The concentration, source of manganese and iron in ferromanganese nodules and therelation between nodules and sedimentary environments are discussed in detail by asynthetical study on chemical information of ferromanganese nodules and correspondingsediment, pore water and geological, biological (bacteria) information in 26 stations fromthe North Pacific region (7- 13°N, 178- 165°W). The result shows that (i) the concen-tration and distribution characteristics of magnese and iron in ferromanganese nod-ules differ in different types of nodules, however, the concentration decreases with theincrease in grain sizes of nodules; (ii) the source of iron in different types of nodulesis basically the same, i. e. the slow sedimentation of overlying water; (iii) manganesein nodules comes mainly from the diffusion of Mn~(2+) in the pore water, and Mn~(2+) fromthe reduction of Mn~(4+) in sediments by the medium of bacteria. As the distribution of bac-teria is believed to be strongly affected by the sedimentary envi 相似文献
143.
144.
Thermal analysis of polymeric materials looked at from the environmental and recycling point of view
This paper presents DSC investigations on the curing kinetics of an epoxy-polyester (EP/PE) powder coating system with two different accelerators and on the crystallization behaviour of a semicrystalline thermoplastic containing regranulate. In addition thermal degradation and entropy relaxation effects of an amorphous, thermoplastic due to different injection moulding parameters are discussed. Thermogravimetry results are presented for quantitative analysis of rubber, and for elucidating problems which may arise during the injection moulding of thermoplastic regranulate which is obtained from painted rejects. The measurements were carried out using NETZSCH DSC 200 (heat flux DSC) and thermobalances TG 439 and TG 209. 相似文献
145.
讨论了一类独立但不一定同分布随机环境中随机行走的常返性和非常返性,进而研究了常返性中的正常返,以及在它们基础上逃逸速度的极限性质,从而推广了Solmn的理论框架。 相似文献
146.
We consider the fractal percolation process on the unit square with fixed decimation parameterN and level-dependent retention parameters {p
k}; that is, for allk ⩾ 1, at thek th stage every retained square of side lengthN
1−
k is partitioned intoN
2 congruent subsquares, and each of these is retained with probabilityp
k. independent of all others. We show that if Πk
p
k =0 (i.e., if the area of the limiting set vanishes a.s.), then a.s. the limiting set contains no directed crossings of the
unit square (a directed crossing is a path that crosses the unit square from left to right, and moves only up, down, and to
the right). 相似文献
147.
The behaviour of allylbutyltin dichloride in water, water–ethanol and water–hexane media, under either homogeneous or heterogeneous conditions, has been studied. 1,3-Diallyl-1,3-dibutyl-1,3-dichlorodistannoxane, butyltin di(hydroxy)chloride and butyltin trichloride arise from the solvolytic, acid–base and degradation processes. The degradation process involving the cleavage of the tin–carbon allyl bond has been interpreted to occur via an intramolecular reaction at the expense of the cation [Bu(CH2=CHCH2)Sn(OH)(H2O)n]+. The mechanistic pathway is ascribable to an internal interaction of the electrophilic cation with a bonded water molecule. This mechanistic proposal may be of some help with understanding of the chemical degradation of diorganotin derivatives in aquatic environments. 相似文献
148.
针对工科学生未来职业的特点,本文强调对工科大学生的信息教育要突破传统文检课的范畴,在确定使学生具有强烈的信息情报意识、较强的情报力以及树立与信息机构及专业人员合作意识的目标的前提下,提出教学过程应体现:学以致用、前瞻性和实践性原则. 相似文献
149.
燃气轮机考虑经济性和环保因素的热力分析 总被引:6,自引:1,他引:5
主要符号表人,从,C,H年运行小时数对热效率风,i二1,2价格方程的系数Hu燃料低位发热量雷压比c燃料含碳百分比d贴现率,温比CO投资额J单位质量C02罚款Cj年均燃料费M比例系数下标Cth年均运行维修费N电站容量0基准值COE发电成本。运行年限C发电成本E考虑变工况的系数P单位功率价格…最佳值G空气流量马单位能量燃料价格,热效率G,燃料流量产年投资费用率1概述在进行动力机械的循环热力分析时,结合经济因素与环保因素来定量进行,是实际生产的要求,也是热力循环分析的一次创新。本文将以燃气轮机发电机组为例,对此进行首次试探,… 相似文献
150.