A comparison between reliability analyses based primarily on disjointness or statistical independence: The case of the generalized indra network

A switching expression is readily convertible to a reliability expression if (a) all ORed terms are disjoint, and (b) all ANDed sums are statistically independent. The usual approach of system reliability analysis makes a primary use of (a) and a secondary use of (b). An alternative approach reverses the roles of (a) and (b). Symbolic reliability expressions for the source-to-terminal reliability of a generalized Indra network (GIN) with nonidentical components are derived by the two approaches. For this particular case, the second approach leads to a shorter, more elegant derivation and simpler novel results. Typical plots of the GIN reliability functions are presented and their properties are discussed.     

Normalized Efficient Routing Protocol for WSN

WSNs （wireless sensor networks） consist of thousands of tiny nodes having the capability of sensing, computation, and wireless communications. Unfortunately these devices are limited energy devices, that is means we must save energy as much as possible, to increase network life time as long as possible. In this paper we introduce NEER--normalized energy efficient routing protocol that increases network life time through switching between AODV protocol that depends on request-reply routing, and MRPC that depends on residual battery in routing.     

Alkyl amides and nitriles as novel tracers for biomass burning

The occurrence of n-alkanoic acids, amides, and nitriles in samples of aerosol particulate matter from Kuala Lumpur and Santiago suggests that emissions from cooking and biomass burning are the primary sources of these organic markers in the atmosphere. It is proposed that fatty acids react with ammonia during biomass burning or combustion to produce amides and nitriles, which can be applied as useful biomarker tracers. To test this hypothesis, nonadecanoic acid and hexadecanamide were used as reactants in hydrous pyrolysis experiments. These experiments produced amides and nitriles and indicated that ammonia is an essential agent in their formation. Thus amides and nitriles are of utility as indicators for input from combustion and biomass burning in the ambient atmosphere.     

Logic design of NAND(NOR) circuits by the entered-map-factoring method

This paper presents an entered-map version of the map factoring method for the logic design of NAND(NOR) circuits. The new version has a better variable-handling capability as well as pedagogical advantages. It is demonstrated by several examples, and is reported to have a favourable students' response.     

A switching-algebraic analysis of consecutive-k-out-of-n:F systems

Switching-algebraic techniques are utilized in a simple and instructive derivation of the linear-cost recursive relation of consecutive-k-out-of-n:F systems.     

Indexes of a telecommunication network

Two recently proposed performance indexes for telecommunication networks are shown to be the s-t and overall versions of the same measure, namely, the mean normalized network capacity. The network capacity is a pseudo-switching-function of the branch successes, and hence it means value is readily obtainable from its sum-of-products expression. Three manual techniques of conventional reliability analysis are adapted for the computation of the proposed performance indexes: a map procedure, reduction rules, and a generalized cutset procedure. Four tutorial examples illustrate these techniques and demonstrate their computational advantages over the state-enumeration technique     

Comments on `An efficient nonrecursive algorithm for computing thereliability of k-out-of-n systems' by A.K. Sarje andE.V. Prasad

The commenter points out that the iterative structure of the algorithm given in the above-titled paper (see ibid., vol.38, no.2, p.234-5, 1989) duplicates that of an earlier algorithm by the commenter. Furthermore, he shows that it does not have the best spatial or temporal complexity among existing algorithms     

Joint block and stream cipher based on a modified skew tent map

Image encryption is very different from that of texts due to the bulk data capacity and the high redundancy of images. Thus, traditional methods are difficult to use for image encryption as their pseudo-random sequences have small space. Chaotic cryptography use chaos theory in specific systems working such as computing algorithms to accomplish dissimilar cryptographic tasks in a cryptosystem with a fast throughput. For higher security, encryption is the approach to guard information and prevent its leakage. In this paper, a hybrid encryption scheme that combines both stream and block ciphering algorithms is proposed in order to achieve the required level of security with the minimum encryption time. This scheme is based on an improved mathematical model to cover the defects in the previous discredited model proposed by Masuda. The proposed chaos-based cryptosystem uses the improved Skew Tent Map (STM) RQ-FSTM as a substitution layer. This map is based on a lookup table to overcome various problems, such as the fixed point, the key space restrictions, and the limitation of mapping between plain text and cipher text. It uses the same map as a generator to change the byte position to achieve the required confusion and diffusion effects. This modification improves the security level of the original STM. The robustness of the proposed cryptosystem is proven by the performance and the security analysis, as well as the high encryption speed. Depending on the results of the security analysis the proposed system has a better dynamic key space than previous ones using STM, a double encryption quality and a better security analysis than others in the literature with speed convenience to real-time applications.

     

Indoor 222Rn concentration measurements in some buildings of Hebron province during the winter season of the year 2000

In this study, we report on the indoor radon concentration levels in a number of locations scattered in the Hebron province, Palestine. The measurements were performed during the winter season of the year 1999/2000 using the CR-39 detectors. The radon concentration levels were found to vary from 23 to 580 Bq m(-3). The arithmetic average of the obtained radon concentration levels was found to be 91 Bq m(-3). It was found that most of the radon concentration levels in houses and school rooms are below the low reference levels limits. Most of the high-radon concentration levels were found in unpainted storage rooms.     

On Reliability Evaluation by Network Decomposition

A simple algorithm for evaluating the symbolic terminal-pair reliability of a complex system is presented. The system graph is decomposed into two subgraphs through a minimal cut. The system success is expressed in terms of certain successes of these subgraphs, and then changed into an equivalent disjoint expression which is directly converted on a one-to-one basis into a reliability expression. It yields unusually simple reliability expressions. The algorithm can be computerized but has not been done. Three examples illustrate the algorithm and compare it with other algorithms.