SOI抗总剂量辐射加固工艺栅氧可靠性研究

文章对采用了埋层二氧化硅抗总剂量加固工艺技术的SOI器件栅氧可靠性进行研究,比较了干法氧化和湿法氧化工艺的栅氧击穿电荷,干法氧化的栅氧质量劣于湿法氧化。采用更敏感的12.5nm干法氧化栅氧工艺条件,对比采用抗总剂量辐射加固工艺前后的栅氧可靠性。抗总剂量辐射加固工艺降低了栅氧的击穿电压和击穿时间。最后通过恒压法表征加固工艺的栅氧介质随时间击穿(TDDB)的可靠性,结果显示抗总剂量辐射加固工艺的12.5nm栅氧在常温5.5V工作电压下TDDB寿命远大于10年,满足SOI抗总剂量辐射加固工艺对栅氧可靠性的需求。     

对服务率可变的T-SPH/M/1/N排队基于广义特征值方法的分析

本文讨论服务率依赖于当前系统中顾客数的有限T-SPH/M/1/N排队,其中TSPH表示连续时间可数状态吸收生灭过程吸收时间的分布.对该排队模型,可以用水平无限位相有限的拟生灭(QBD)过程进行建模.通过用广义特征值方法对该QBD过程进行分析,得到了T-SPH/M/1/N排队的平稳到达队长分布.另外,为了说明我们方法的有效性,还用几个数值例子对模型进行了分析,以刻画参数变化对系统性能的影响.     

基于QBD模型的混合信道分配技术研究

混合信道分配技术兼有同定信道分配技术和动态信道分配技术的优点.为提高信道资源利用率,通过建立拟生灭过程的数学模型,选择切换保留混合优先级算法,然后通过模型平稳分布的求解得出性能指标的数学表达式,通过仿真对其性能进行比较.结果表明混合信道分配略差于动态信道分配,但优于同定信道分配.     

Performance analysis of call centers with abandonment,retrial and after-call work

This paper considers a multiserver queueing model with abandonment, retrial and after-call work for call centers. Upon a phone call, customers that find a free call line occupy the line immediately while those who see all the call lines busy are blocked and join an orbit. Customers holding a call line are served according to the first-come first-served discipline. After completing a call, the customer leaves the system while the server must start an after-call work and the call line is released for a newly arrived customer. Waiting customers may abandon after some waiting time and then either join the orbit or leave forever. Customers in the orbit retry to hold a free call line after some time. We formulate the queueing system using a continuous-time level-dependent quasi-birth-and-death process for which a sufficient condition for the ergodicity is derived. We obtain a numerical solution for the stationary distribution based on which performance measures such as the waiting time distribution and the blocking probability are derived. Using Little’s law, we obtain explicit formulae which verify the accuracy of the numerical solution. We compare our model with some simpler models which do not fully take into account some human behaviors. The comparison shows significant differences implying the importance of our model. Numerical results show various insights into the performance of call centers.     

A method for calculating successive approximate solutions for a class of block banded M/G/1 type Markovian models

This paper presents an efficient equilibrium solution algorithm for a class of infinite block banded M/G/1 type Markov chains. By re-blocking the states, these are a class of the so-called quasi-birth-and-death (QBD) type chains. The proposed algorithm is not based on an iterative approach, so that the exact solution can be computed in a known finite number of steps. The key point on which the algorithm is based is the identification of a linear dependence among variables. This dependence is expressed in terms of a companion matrix. The equilibrium solution of the Markov chain is obtained operating on this matrix.

An attractive feature of the algorithm is that it allows the computation of a succession of approximate solutions with growing accuracy, until the exact solution is obtained in a finite number of steps. The class of block-banded M/G/1 type Markov chains we consider requires that the lower diagonal block is invertible and that the chain is ergodic. However, many models arising from telecommunication systems satisfy this restriction. Results for a case study show that the proposed algorithm is efficient and quite accurate, even when providing approximate solutions.     

Modelling of brain consciousness based on collaborative adaptive filters

A novel method for the discrimination between discrete states of brain consciousness is proposed, achieved through examination of nonlinear features within the electroencephalogram (EEG). To allow for real time modes of operation, a collaborative adaptive filtering architecture, using a convex combination of adaptive filters is implemented. The evolution of the mixing parameter within this structure is then used as an indication of the predominant nature of the EEG recordings. Simulations based upon a number of different filter combinations illustrate the suitability of this approach to differentiate between the coma and quasi-brain-death states based upon fundamental signal characteristics.     

An algorithmic analysis of multi-server vacation model with service interruptions

Motivated by the trade-off between reliability and utilization level of a stochastic service system, we considers a Markovian multi-server vacation queueing system with c unreliable servers. In such a system, some servers may not be available due to either planned stoppage (vacations) or unplanned service interruptions (server failures). The vacations are controlled by a threshold policy. With this policy, at a service completion instant, if d (?c) servers become idle, they take a vacation together and will keep taking vacations until they find at least c − d + 1 customers are in the system at a vacation completion instant, and then they return to serve the queue. In addition, all on-duty servers are subject to failures and can be repaired within a random period of time. We formulate a quasi-birth–death (QBD) process, establish the stability condition, and develop a computational algorithm to obtain the stationary performance measures of the system. Numerical examples are presented to show the performance evaluation and optimization of such a system. The insights gained from this model help practitioners make capacity and operating decisions for this type of waiting line systems.     

Markovian analysis of production lines with Coxian-2 service times

This paper is concerned with the analysis of reliable production lines. The service times at each station of the line are assumed to follow the Coxian-2 distribution. Raw material arrives at the first station of the line which is assumed that is never empty. Buffers of non-identical capacities are allowed between successive stations. The structure of the transition matrices of these specific type of production lines is examined and a recursive algorithm is developed for generating them, for any number of stations K . This method allows one to obtain the exact solution of a sparse linear system by the use of the Gauss–Seidel method. From the solution of these systems the throughput rate of the production lines is calculated. However, this algorithm is not computationally efficient as it is restricted by the size of the problem. The main contribution of this paper is the study of the transition matrices of production lines with Coxian service times.     

超薄氧化层制备及其可靠性研究

文章简述了超薄氧化层SiO2,的击穿机理,采用了恒定电流法表征超薄氧化层TDDB效应,并研究了清洗方法,氧化温度,氧化方式等工艺因素对超薄氧化层的可靠性影响.实验表明,在850℃、900℃等高温条件下,可通过干氧N/O分压的方法制备厚度4nm~5nm、均一性小于2.0%超薄氧化层;RCA清洗工艺过程中,APM中的NH3...     

A probabilistic interpretation of cyclic reduction and its relationships with logarithmic reduction

We provide a simple convergence proof for the cyclic reduction algorithm for M/G/1 type Markov chains together with a probabilistic interpretation which helps to understand better the relationships between logarithmic reduction and cyclic reduction.