Sharif Digital Repository

In this study, we presented a method for distributing data storage by using residue number system for mobile systems and wireless networks based on peer to peer paradigm. Generally, redundant residue number system is capable in error detection and correction. In proposed method, we made a new system by mixing Redundant Residue Number System (RRNS), Multi Level Residue Number System (ML RNS) and Multiple Valued Logic (MVL RNS) which was perfect for parallel, carry free, high speed arithmetic and the system supports secure data communication. In addition it had ability of error detection and correction. In comparison to other number systems, it had many improvements in data security, error... 

A routing algorithm defines a route which packet traverses to get to destination. In this research we study some kind of routing algorithms that are used in internal connections networks of multi-processor and multi-computers systems. Then we discuss about some routing algorithms which have been implemented network on chip architecture. First, we present a group of routing algorithms based on various criterions, and review so-called category. Afterwards, we study adaptive and deterministic routing algorithms and express circular model applying in internal connections networks and its governing rules in order to prevent dead lock. Then we survey adaptive algorithms such as Deflection routing,... 

This paper proposes a decentralized algorithm to organize an ad-hoc sensor network into clusters. Each sensor operates independently, monitoring communication among others. Those sensors which have many neighbors that are not already part of a cluster are likely candidates to creating a new cluster by declaring themselves to be a new cluster-head. The Clustering Algorithm via Deadline Timer (CADT) provides a protocol whereby this can be achieved and the process continues until all sensors are part of a cluster. Because of the difficulty of analyses simplified models are used to study and abstract its performance. A simple formula to estimate the number of clusters which will be formed in an... 

This paper presents different applications of a vector model developed by the authors in Brushless Doubly-Fed Machine (BDFM) studies including analysis, control and simulations. The BDFM considered consists of a nested-loop type rotor. The vector model, which considers all the loops in each rotor nest, is derived using BDFM coupled-circuit model equations and by applying appropriate vector transformations. Three vector transformations are employed for the derivation of vector model corresponding to two three-phase windings in the stator and the rotor circuit. Each transformation consists of an angle which is, in general, unspecified and must be assigned appropriately depending on the... 

Thermal expansion and hot deformation are two phenomena causing dimensional errors in investment casting. This error occurs in dimensions between the die and wax pattern. Therefore, the wax's thermo-physical and thermo-mechanical properties, the metal die features, and the process parameters affect the dimensions of the wax pattern. Some important effective process parameters are the injection temperature, die temperature, and holding time. In this paper, the effect of injection parameters on the dimensional accuracy of the wax model created by a metallic die is studied. The Taguchi formulation based on the design of experiments is applied to obtain the optimum condition in achieving the... 

Reliability and energy consumption are two of the main constraints in wireless sensor networks (WSNs). In this paper, a novel energy efficient and high speed error control scheme is introduced that is based on the Redundant Residue Number System (RRNS) allowing real-time application of WSNs. The proposed approach employs a new 3-moduli set {22n+1, 2 2n1-1, 2n- 1 } and an efficient reverse converter which relies on the Mixed Radix Conversion (MRC) algorithm and achieves significant improvements both in terms of conversion delay and hardware design. In order to obtain error controllability, two-redundant-moduli set 23n+1 - 1, 24n+1 - 1 is also added to the main 3-moduli set. The theoretical... 

The paper deals with a new reliable data transport protocol for wireless sensor networks, referred as RDTP. One of the most prominent challenges in wireless sensor networks is reliable transport of data from sensor nodes to sink node. For designing protocols for such networks hardware, some constraining factors associated with energy and processing power must be taken into consideration. There are two generic methods, ARQ and FEC to achieve reliable data transport. Here, a reliable data transport protocol for wireless sensor networks is proposed, in which an efficient moduli set in redundant residue number system has been employed. The modulus set is exploited as a means for adding... 

This study investigated the differential effects of focus-on-form (FonF: explicit instruction followed by focused tasks) and focus-on-forms (FonFS: explicit instruction followed by controlled exercises) on learning English lax vowels (i.e., /ɪ/, /ʊ/, /ʌ/) by Persian English as a foreign language (EFL) learners. To this end, 48 learners took a voluntary 6-hour course: the experimental group (n = 17) received FonF, the comparison group (n = 16) received FonFS, and the control group (n = 15) engaged in theme-based discussions with no focus on the target vowels. Learners’ pronunciations were elicited in controlled read-aloud and spontaneous picture description tasks and acoustically measured for... 

Purpose - Dimensional accuracy analysis of wax model created by room temperature vulcanization (RTV) silicone rubber molding to be used in investment casting is presented. The purpose of this paper is to discuss the effective parameters of dimensional accuracy in RTV tooling technique. Design/methodology/approach - After producing a pattern by stereolithography (SLA) and then creating the RTV silicone rubber mold by the SLA pattern, dimensional accuracy of wax models produced by RTV tool are analyzed. Design of experiments (DOE) using the Taguchi approach is used for analysis and determination of optimum condition. Findings - Experiments show that the dimensional accuracy in RTV technique is...