Evaluation of Lifetime Bounds of Wireless Sensor Networks

In this paper we estimate lifetime bounds of a network of motes which communicate with each other using IEEE 802.15.4 standard. Different frame structures of IEEE 802.15.4 along with CSMA/CA medium access mechanism are investigated to discover the overhead of channel acquisition, header and footer of data frame, and transfer reliability during packet transmission. This overhead makes the fixed component, and the data payload makes the incremental component of a linear equation to estimate the power consumed during every packet transmission. Finally we input this per-packet power consumption in a mathematical model which estimates the lower and upper bounds of routings in the network. We also implemented a series of measurements on CC2420 radio used in a wide range of sensor motes to find the fixed and incremental components, and finally the lifetime of a network composed of the motes using this radio.Comment: 10 pages, 6 figure

Significant reliability improvement of NMR systems

Majority voted redundancy is increasingly implemented in fault-tolerant design today. In this technique, a voter receives parallel bits from an odd number of digital components and votes for the majority. Reliability improvement is the main focus of every fault tolerant system design. In this paper, we first present a viable alternative to the voting redundancy concept in order to significantly increase the reliability of conventional voting systems for five parallel components or higher. Then, an implementation of this novel concept is described.Pro konstrukci systémů odolných poruchám se velmi často používá redundance s hlasovacím členem. Součástí systému je hlasovací člen, který vyhodnocuje lichý počet výstupů replikovaných realizací zálohovaného prvku systému, přičemž hlasovací člen jako výstup zvolí tu hodnotu, která má vyšší počet výskytů. Zlepšení spolehlivosti je hlavním zaměřením každého návrhu systému odolného poruchám. V tomto příspěvku nejdříve představíme aplikovatelnou strukturu hlasovací funkce, aby se výrazně zvýšila spolehlivost konvenčních hlasovacích systémů pro pětinásobné a vyšší zálohování. Poté je popsána implementace tohoto nového pojetí.Majority voted redundancy is increasingly implemented in fault-tolerant design today. In this technique, a voter receives parallel bits from an odd number of digital components and votes for the majority. Reliability improvement is the main focus of every fault tolerant system design. In this paper, we first present a viable alternative to the voting redundancy concept in order to significantly increase the reliability of conventional voting systems for five parallel components or higher. Then, an implementation of this novel concept is described

General solutions for MTTF and steady-state availability of NMR systems

Voting redundancy is a well-known technique to improve the fault tolerance of digital systems. Calculation of reliability and availability is a necessary part of every fault tolerant system design. Conventional techniques, including block diagram method, are unsuccessful when there is dependent failure, repair, or standby operation in the system. Use of Markov models also almost fails when system is composed of many elements or is repairable. However, the alternatives to reliability and availability, i.e. mean time to failure and steady state availability, respectively, are easily measurable using Markov graphs. In this paper, novel general form solutions for calculation of mean time to failure and steady-state availability of N-modular redundancy systems are presented.Hlasovací redundance je dobře známá technika pro zlepšení odolnost proti chybám digitálních systémů. Výpočet spolehlivosti a dostupnosti je nezbytnou součástí každého systému odolného proti chybám návrhu. Běžné techniky, včetně metody blokového schéma, jsou neúspěšné, pokud jsou závislé na kvantifikaci selhání, oprav nebo pohotovostních režimů provozu systému. Použití Markovových modelů také téměř selže, pokud je systém složený z mnoha prvků nebo jej lze opravit. Nicméně, alternativy k spolehlivosti a dostupnosti, tj střední doba do poruchy, respektivě ustálenou dostupnost, jsou snadno měřitelné pomocí Markovových grafů. V tomto článku je prezentováno nové řešení pro výpočet průměrné doby do poruchy a ustáleného stavu dostupnosti N-modulárních redundantních systémů.Voting redundancy is a well-known technique to improve the fault tolerance of digital systems. Calculation of reliability and availability is a necessary part of every fault tolerant system design. Conventional techniques, including block diagram method, are unsuccessful when there is dependent failure, repair, or standby operation in the system. Use of Markov models also almost fails when system is composed of many elements or is repairable. However, the alternatives to reliability and availability, i.e. mean time to failure and steady state availability, respectively, are easily measurable using Markov graphs. In this paper, novel general form solutions for calculation of mean time to failure and steady-state availability of N-modular redundancy systems are presented

Discrimination of neutron and photon signals using time and frequency domain data

Two new methods for the digital discrimination of neutrons and gamma-rays in a mixed radiation field are presented. There are many methods available which take advantage of time-domain pulse shape discrimination of these two signals. However, there are no methods based on frequency-domain characteristics of them, in particular using discrete Fourier transform (DFT). Applying DFT, we can distinguish between these radiations much better. Combining time and frequency domain PSDs, we can further increase the discrimination quality while improving computation time to be applicable for field measurements

Neutron/gamma-ray discrimination through measures of fit

Statistical tests and their underlying measures of fit can be utilized to separate neutron/gamma-ray pulses in a mixed radiation field. In this article, first the application of a sample statistical test is explained. Fit measurement-based methods require true pulse shapes to be used as reference for discrimination. This requirement makes practical implementation of these methods difficult; typically another discrimination approach should be employed to capture samples of neutrons and gamma-rays before running the fit-based technique. In this article, we also propose a technique to eliminate this requirement. These approaches are applied to several sets of mixed neutron and gamma-ray pulses obtained through different digitizers using stilbene scintillator in order to analyze them and measure their discrimination quality

Investigate The Relationship Between Cost Management Strategy, Organization Size, Growth Options and The Performance Of Companies In Tehran Stock Exchange

This study aimed to investigate the relationship between cost management strategy, organization size and growth Options on the performance of the company. In this regard, the financial statements of 76 companies listed in Tehran Stock Exchange for the years 2009 to 2013 were analyzed. In this study, cost management strategy (the ratio of capital expenditure to sales, sales of the book value of fixed assets) and size (natural logarithm of total assets) and growth Options (market value of assets to book value of assets) as a variable. independent, and firm performance (return on assets, sales growth) was used as the dependent variable, so that the relationship between strategy, size, growth Options and firm performance during a 5-year period studied. The method used for data collection, library and field. To test the hypotheses of the model Autoregressive conditional heteroscedasticity (ARCH) and generalized regression model, the conditional heteroscedasticity (GARCH) were analyzed using the software Eviews8. And significance was determined using a Z score and likelihood ratio. The criteria for the variable sales strategy to sell the book value of fixed assets and the capital expenditure of a significant and positive relationship with sales growth. In the capital, Tehran Stock Exchange Market participants are recommended to consider it as the time-varying volatility and time efficiencies associated with corporate assets can be public relations strategy, cost management and growth Options of the company described. Also associated with the company's sales growth can be described by the relationship between the size and cost management strateg