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101.
A mathematical model based on a straightforward geometrical background is developed which enables predictions of a transition of one dispersed phase to a cocontinuous one (i.e., the percolation threshold) on addition of another dispersed phase during melt mixing in ternary polymer blends. The present work concerns only ternary blends with two separate dispersions of the inner phases in which no encapsulation takes place. In addition, in order to simplify the model, one of the inner phases was represented by hard, nondeformable microspheres The expression developed describes well an experimental relationship between the percolation threshold, the concentration above which the former dispersed phase transforms to a continuous one, and concentrations of both inner phases. The results agree well with the experimental data obtained in a previous work. 相似文献
102.
René Michel 《Extremes》2007,10(3):83-107
The investigation of multivariate generalized Pareto distributions (GPDs) has begun only recently. For further progress with
these distributions simulation methods are an important part. We describe several methods of simulating GPDs, beginning with
an efficient method for the logistic GPD. The algorithm is based on the Shi transformation, which was already used for the
simulation of multivariate extreme value distributions (EVDs) of logistic type. In the sequel another algorithm is presented
simulating a broader class of GPDs. Due to its numerical complexity it is only practicably applicable in low dimensions. A
method is given to generate unconditional GPD random vectors from conditionally GPD distributed random vectors. A short application
of the simulation methods in the analysis of a real hydrological data set concludes the article. The simulation algorithms
are available on the author’s home page .
相似文献
103.
为满足卫星激光通信中超高速数据传输的特殊要求,采用电子束和离子辅助沉积技术,制备了532 nm、632 nm和1 064 nm波长处高反射,808 nm和1 550 nm处高透射的多波段滤光膜.选取了H4和SiO2作为高低折射率材料,通过对膜系设计曲线的不断优化,减少了灵敏层的个数,得到了相对易于制备的膜系结构;采用电子束加热蒸发方法并加以离子辅助沉积系统制备薄膜, 采用光控与晶控同时监控的方法控制膜厚;通过不断调整工艺,提高了薄膜的抗激光损伤能力,减小了膜厚控制误差,提高了透射波段的透过率及反射波段的反射率,最终得到了光谱性能较好的滤光膜.该薄膜能够承受雨淋、盐雾、高低温等环境测试,满足使用要求. 相似文献
104.
105.
106.
The nonlinear wavelet estimator of regression function with random design is constructed. The optimal uniform convergence
rate of the estimator in a ball of Besov spaceB
3
p,q
is proved under quite general assumpations. The adaptive nonlinear wavelet estimator with near-optimal convergence rate in
a wide range of smoothness function classes is also constructed. The properties of the nonlinear wavelet estimator given for
random design regression and only with bounded third order moment of the error can be compared with those of nonlinear wavelet
estimator given in literature for equal-spaced fixed design regression with i.i.d. Gauss error.
Project supported by Doctoral Programme Foundation, the National Natural Science Foundation of China (Grant No. 19871003)
and Natural Science Fundation of Heilongjiang Province, China. 相似文献
107.
采用ANSYS进行形变-应力模拟。对不同应力状态下的熔石英表面进行三倍频激光损伤测试,结果发现,预加压应力为0~50 MPa时损伤阈值有明显提高的趋势,用应力耦合作用对此给出了解释:0~50 MPa的预加压应力可以降低和抵消激光辐照产生的张应力破坏,大于50 MPa预应力的耦合作用会使得该处机械性能下降,另外,损伤增长在预应力存在时更容易发生。因此,0~50 MPa预加压应力时的表面预应力可以提高熔石英的抗激光辐照能力。 相似文献
108.
Consider discrete storage processes that are modulated by environmental processes. Environmental processes cause interruptions in the input and/or output processes of the discrete storage processes. Due to the difficulties encountered in the exact analysis of such discrete storage systems, often Poisson flow and/or fluid flow models with the same modulating environmental processes are proposed as approximations for these systems. The analysis of Poisson flow and fluid flow models is much easier than that of the discrete storage processes. In this paper we give sufficient conditions under which the content of the discrete storage processes can be bounded by the Poisson flow and the fluid flow models. For example, we show that Poisson flow models and the fluid flow models developed by Kosten (and by Anick, Mitra and Sondhi) can be used to bound the performance of infinite (finite) source packetized voice/data communication systems. We also show that a Poisson flow model and the fluid flow model developed by Mitra can be used to bound the buffer content of a two stage automatic transfer line. The potential use of the bounding techniques presented in this paper, of course, transcends well beyond these examples.Supported in part by NSF grant DMS-9308149. 相似文献
109.
Frequency-locking and threshold current-lowering effects of a quantum cascade laser and an application in gas detection field 下载免费PDF全文
In this paper,the frequency-locking and threshold current-lowering effects of a quantum cascade laser are studied and achieved.Combined with cavity-enhanced absorption spectroscopy,the noninvasive detection of H_2 with a prepared concentration of 500 ppm in multiple dissolved gases is performed and evaluated.The high frequency selectivity of 0.0051 cm~(-1) at an acquisition time of 1 s allows the sensitive detection of the(1-0) S(l) band of H_2 with a high accuracy of(96.53±0.29)%and shows that the detection limit to an absorption line of 4712.9046 cm~(-1) is approximately(17.26±0.63) ppm at an atmospheric pressure and a temperature of 20 ℃. 相似文献
110.
By analyzing the radiation dose on PIN photodetectors in space radiation environment, the variation of photocurrent and dark current after radiation is obtained. On the basis, the bit error rate of satellite laser communication based on space radiation dose of PIN photodetectors is established. According to simulation, when radiation dose is about 1.6 × 103 Gy and 7 × 104 Gy, bit error rate reaches 10−6 induced by 50 MeV and 10 MeV protons separately; and when radiation dose is within the range of 5 × 10 Gy–6 × 105 Gy, electrons and gamma-ray irradiation also cause increase in bit error rate to 10−6. The principle of damage dose on bit error rate is investigated, and the influence of decision threshold on bit error rate is further discussed. The result shows that when radiation dose is 1 MGy, if decision threshold is increased from 4.3 × 10−7 A to 5.5 × 10−7 A, bit error rate will decrease about 4 orders of magnitude. Hence, a proper decision threshold can improve system bit error rate efficiently. 相似文献