分布式安全组播体系结构的实现

随着因特网不断商业化和用户数量的急剧增加，组播通信中的安全问题受到研究人员的日益关注。许多研究机构提出了解决这些安全问题的体系结构。文章通过分析组播的安全问题和安全服务，给出了设计体系结构中需要注意的问题。在分析这些体系结构的基础上，提出了具有安全策略的DSMA(Dist Iibuted Secure Mumcast Architecture)体系结构，它对Iolus单点故障进行了解决。最后给出了DSMA的实现方案。     

走向客户端的光通信发展探讨

随着客户端业务对带宽和质量需求的增加,当前光通信的一个特点是客户端已成为光通信最大的技术和市场空间.本文从客户端入手,首先指出光通信走向客户端的发展趋势,分析了走向客户端的光通信的特点,接着介绍了几种走向客户端的技术途径,重点分析了PON在客户端光通信网络中的应用特点,最后对客户端接入的组网方式做了进一步的探讨.     

Monetary policy rules in practice: Re-examining the case of Turkey

This paper investigates possible asymmetries in the monetary policy reaction function of the Central Bank of Republic of Turkey over the business cycles. It is found that the bank reacted more aggressively towards output stabilisation during recessions than expansions. The empirical evidence suggests that the inflation targeting policy of the Turkish Central Bank was accommodative rather than stabilising. Furthermore, it is found that although the Central Bank of Republic of Turkey responded to foreign reserves, real exchange rates and short-term capital inflows both in expansion and recession periods, the bank targeted money growth, budget deficits, and net foreign assets only in expansion periods.     

Following the rules: Integrating asset allocation and annuitization in retirement portfolios

Financial advisers have developed standardized payout strategies to help Baby Boomers manage their money in their golden years. Prominent among these are phased withdrawal plans offered by mutual funds including the “self-annuitization” or default rules encouraged under US tax law, and fixed payout annuities offered by insurers. Using a utility-based framework, and taking account of stochastic capital markets and uncertain lifetimes, we first evaluate these rules on a stand-alone basis for a wide range of risk aversion. Next, we permit the consumer to integrate these standardized payout strategies at retirement and compare the results. We show that integrated strategies can enhance retirees’ well-being by 25%-50% for low/moderate levels of risk aversion when compared to full annuitization at retirement. Finally, we examine how welfare changes if the consumer is permitted to switch to a fixed annuity at an optimal point after retirement. This affords the retiree the chance to benefit from the equity premium when younger, and exploit the mortality credit in later life. For moderately risk-averse retirees, the optimal switching age lies between 80 and 85.     

Structured replacement policies for a Markov-modulated shock model

We establish the optimality of structured replacement policies for a periodically inspected system that fails silently whenever the cumulative number of shocks, or the magnitude of a single shock it has received, exceeds a corresponding threshold. Shocks arrive according to a Markov-modulated Poisson process which represents the (controllable or uncontrollable) environment.     

电信市场开放后政府的管制倾向

综合来讲，世界各国对电信行业的管理大致在三个层次上进行：最高政府决策管理层、准政府管理层及民间层。面对电信网络设备的管理主要有强制性管理和非强制性管理两种方式。本文在最后指出了国外电信行业管理的趋势。     

GSM信息安全性研究

本文结合国内的实际情况,通过介绍GSM系统的体系结构,分析了其在系统安全性方面采取的主要措施,也指出了存在的一些潜在安全隐患。     

研究所在新时期如何做好保密工作

随着高科技的迅猛发展、国际互联网的广泛膨用、经济全球化趋势的同益明显，以及知识创新工程的深入，传统的保密工作正受到巨大的冲击。论文从“窃密与反窃密”、“密与非密界定”、“信息安全”等方面分析入手，提出应以信息安全为重点，从加强涉密计算机保密管理、涉密人员教育、提高人员素质、加大保密工作投入、提高科研人员的保密意识等方面做好新时期保密工作。     

Practical Construction and Analysis of Pseudo-Randomness Primitives

We give a careful, fixed-size parameter analysis of a standard (Blum and Micali in SIAM J. Comput. 13(4):850–864, 1984; Goldreich and Levin in Proceedings of 21st ACM Symposium on Theory of Computing, pp. 25–32, 1989) way to form a pseudo-random generator from a one-way function and then pseudo-random functions from said generator (Goldreich et al. in J. Assoc. Comput. Mach. 33(4):792–807, 1986) While the analysis is done in the model of exact security, we improve known bounds also asymptotically when many bits are output each round and we find all auxiliary parameters efficiently, giving a uniform result. These optimizations makes the analysis effective even for security parameters/key-sizes supported by typical block ciphers and hash functions. This enables us to construct very practical pseudo-random generators with strong properties based on plausible assumptions.     

On the tradeoff between optimal order-base-stock levels and demand lead-times

We investigate the tradeoff between finished-goods inventory and advance demand information for a model of a single-stage make-to-stock supplier who uses an order-base-stock replenishment policy to meet customer orders that arrive a fixed demand lead-time in advance of their due-dates. We show that if the replenishment orders arrive in the order that they are placed, then the tradeoff between the optimal order-base-stock level and the demand lead-time is “exhaustive”, in the sense that the optimal order-base-stock level drops all the way to zero if the demand lead-time is sufficiently long. We then provide a sufficient condition under which this tradeoff is linear. We verify that this condition is satisfied for the case where the supply process is modeled as an M/M/1 queue. We also show that the tradeoff between the optimal order-base-stock level and the demand lead-time is linear for the case where the supply process is modeled as an M/D/1 queue. More specifically, for this case, we show that the optimal order-base-stock level decreases by one unit if the demand lead-time increases by an amount equal to the supplier’s constant processing time. Finally, we show that the tradeoff between the optimal order-base-stock level and the demand lead-time is exhaustive but not linear in the case where the supply process is modeled as an M/D/∞ queue. We illustrate these results with a numerical example.