Blocking Probabilities in Mobile Communications Networks with Time-Varying Rates and Redialing Subscribers

Call-blocking probabilities are among the key performance measures in mobile communications networks. For their analysis, mobile networks can be modelled as networks of Erlang loss queues with common capacity restrictions dictated by the allocation of frequencies to the cells of the network. However, due to the time-varying load offered to the cells of such networks, blocking probabilities usually cannot be obtained in closed form. The relation between networks of Erlang loss queues and networks of infinite server queues, for which the time-dependent occupancy distribution is multidimensional Poisson, suggests to use that distribution as approximate distribution for the network of Erlang loss queues. This paper extends this so-called Modified Offered Load (MOL) approximation to networks of Erlang loss queues, and also allows subscribers that find their call blocked to redial to continue their call. For GSM networks operating under Fixed Channel Allocation, it is shown that blocking probabilities are increasing in the redial rates so that the MOL approximation that is most accurate for maximal redial rates turns out to be fairly accurate for the resulting upper bound for blocking probabilities. The accuracy is explicitly evaluated in an application of the results towards blocking probabilities in a hot spot travelling along a road through a GSM network.     

72172Hf和72174Hf高K多准粒子低激发带的粒子数守恒计算

用处理推转壳模型的粒子数守恒(PNC)方法,分析了稀土变形核^172,174Hf的基态带和低激发高K多准粒子带的运动学转动惯量J⁽¹⁾随角频率ω的变化及其微观机制,特别是被拆散核子的Pauli堵塞效应的重要影响.实验观测到的J⁽¹⁾和顺排角动量随角频率的变化在PNC计算中得到较好的重现.计算中无自由参数.分析表明,高K多准粒子带的J⁽¹⁾随ω的变化与基态带不同,主要来自高N(j)闯入态的堵塞效应.     

Synthesis of Methyl-2, 3-Di-O-Methyl 6-Deoxy-3-C-Methyl-a-D-Gulopyranoside

Methyl 2,2-di-O-methyl-6-C-methyl-α-D-gulopyranoside has been synthesized from D-glucose. The introduction of methyl branching at 3-position was achieved by the Grignard reaction.     

带有肖特基漏极和场板结构的反向阻断垂直MOSFET研究

提出了一种采用肖特基漏极(SD)与场板相结合、实现硅基垂直MOSFET器件反向阻断应用的技术。基于该技术,采用二维仿真提出并研究了两种新型垂直MOSFET器件,即带有垂直场板(VFP)的SD-VFP-MOS器件和带有倾斜场板(SFP)的SD-SFP-MOS器件。相比采用肖特基漏极的MOSFET (SD-MOS)和采用超结和肖特基漏极的MOSFET(SD-SJ-MOS),所提出的SD-VFP-MOS,尤其是SD-SFP-MOS,反向击穿电压有显著提高,且几乎不影响导通特性。开展了器件的开态电流密度、关态电势分布、关态电流密度和电场分布分析,揭示了VFP和SFP提高器件反向阻断能力的内在机理。详细讨论了场板结构参数对器件反向击穿电压和场板效率的影响,研究结果对于SD-VFP-MOS和SD-SFP-MOS的设计具有重要意义。     

5G通信基站对邻频C波段卫星地球站干扰的分析与处置

为了解决5G通信基站对C波段单收地球站的干扰共存问题,选取一个干扰的实例作为研究对象,分析干扰成因,并通过实测数据得出带外抑制比ACLR是影响邻频干扰大小的主要因素。根据地球站的干扰保护准则并通过工程实践,可计算得出两系统邻频共存时需要保持的ACLR。     

Effects of sintering additives on the mixed transport properties of ceria-based materials under reducing conditions

Commercial Ce_0.8Gd_0.2O_2– nanopowders and alternative precursors synthesized by a freeze-drying method were used to obtain samples with and without Co addition as a sintering agent. Two percent Co-doped samples were sintered at 1150 °C and 1500 °C and undoped samples were sintered at 1500 °C or 1600 °C to obtain samples with relative densities in the range 92–94%. The total conductivity and the relative roles of bulk and grain boundary conductivity were studied by impedance spectroscopy. These results demonstrated that additions of Co play a very significant effect on the grain boundary behaviour, which is spoiled when the sintering temperature is excessive. Significant differences in grain boundary behaviour were also found between samples prepared from different precursor powders. The electronic conductivity of these materials was evaluated by an ion-blocking method and revealed that samples containing Co additions as a sintering additive possess somewhat lower n-type conductivity under identical conditions of temperature and oxygen partial pressure. The differences tend to vanish when these Co-doped samples are fired at high temperatures (1500 °C).Abbreviations CGO Ce_0.8Gd_0.2O_1.9 - FD freeze-dried - RH rhodiaPresented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, 10–12 April 2003     

示波极谱法测定某些食品对亚硝酸根的阻断率

在高氯酸底液中，当有硫氰酸盐作催化剂时，亚硝酸根能迅速与二苯胺定量生成Ｎ－亚硝基二苯胺，并产生灵敏的催化电流。峰电位Ｅｐ＝－０．６１Ｖ（ｖｓ．ＳＥＣ），检测限２×１０＾－８ｍｏｌ／Ｌ，线性范围０～３×１０＾－５ｍｏｌ／ Ｌ，测定了茶叶等几种称范匝窍跛岣淖瓒下剩晃诹瑁梗梗保ィ滩瑁福常矗ィ笏猓矗担担ィ保罚矗ィ劢梗福ィ胛南妆ǖ老辔呛希刖浞椒ㄏ啾龋痉ň哂屑虮悖槊艉妥既     

A novel evaluation metric based on visual perception for moving target detection algorithm

Traditional performance evaluation index for moving target detection algorithm, whose each index’s emphasis is different when it is used to evaluate the performance of the moving target detection algorithm, is inconvenient for people to make an evaluation of the performance of algorithm comprehensively and objectively. Particularly, when the detection results of different algorithms have the same number of the foreground point and the background point, the algorithm’s each traditional index is the same, and we can’t use the traditional index to compare the performance of the moving target detection algorithms, which is the disadvantage of traditional evaluation index that takes pixel as a unit when calculating the index. To solve this problem, combining with the feature of human’s visual perception system, this paper presents a new evaluation index-Visual Fluctuation (VF) based on the principle of image block to evaluate the performance of moving target detection algorithm. Experiments showed that the new evaluation index based on the visual perception makes up for the deficiency of traditional one, and the calculation results are not only in accordance with visual perception of human, but also evaluate the performance of the moving target detection algorithm more objectively.     

A Node-Level Blocking Probability Analysis for WRONs

This work presents the blocking performance of a single node with (full or limited) wavelength conversion in wavelength routed optical networks (WRON) based on the theory of probability. A blocking probability model is proposed. Particularly, we pay more attention to investigate wavelength routing node performance improvement by using the more feasible case of limited wavelength conversion. Based on our analytical model, we calculate the blocking probability for a single wavelength routing node and then make a simulation to validate it. It is shown that a node with low conversion degrees having a small number of fiber link ports and a large number of wavelengths per link is a more realistic choice.