2018-01-22T21:32:44Z
http://ijste.shirazu.ac.ir/?_action=export&rf=summon&issue=445
Iranian Journal of Science and Technology Transactions of Electrical Engineering
2228-6179
2228-6179
2014
38
E1
DESIGN AND IMPLEMENTATION OF PRECISE HARDWARE FOR ELECTRICAL IMPEDANCE TOMOGRAPHY (EIT)
Electrical Impedance Tomography (EIT), is one of the safest medical imagingtechnologies and can be used in industrial process monitoring. In this method, image of electricalconductivity (or electrical impedance) distribution of the inner part of a conductive subject can bereconstructed. The image reconstruction process is done by injecting an accurate current into theboundary of a volume conductor (Ω), measuring voltages around the boundary (∂Ω) andtransmitting them to a computer, and processing on acquired data with software (e.g. MATLAB).The image would be reconstructed from the measured peripheral data by using an iterativealgorithm. A precise instrumentation (EIT hardware) plays a very important and vital role in thequality of reconstructed images. In this paper, we have proposed a practical design of a low-costprecise EIT hardware including, a high output impedance VCCS (Voltage-Controlled CurrentSource) with pulse generation part, precise voltage demodulator and measuring parts, a highperformance multiplexer module, and a control unit. All the parts have been practically andaccurately tested with successful results, and finally the proposed design was assembled on PCB.The quality of experimental results at the end of this paper, (reconstructed images by using theimplemented system), confirms the accuracy of the proposed EIT hardware.
EIT
electrical impedance tomography
EIT hardware
EIT instrumentation
EIT current source
2014
06
01
1
20
http://ijste.shirazu.ac.ir/article_2095_47f0df6ce573e11ccabf073676e496fa.pdf
Iranian Journal of Science and Technology Transactions of Electrical Engineering
2228-6179
2228-6179
2014
38
E1
BANDWIDTH OPTIMIZATION TO ACHIEVE MINIMUM PHASE NOISE IN FREQUENCY SYNTHESIZERS
This paper analyzes the phase noise of the single loop second-order frequencyfractional-N synthesizer. The aim of this paper is the reduction of the output phase noise in theapplication of commercial and military subsystems as well as general local oscillators. Themathematical model of PLL based frequency synthesizer is analyzed to develop the minimumphase noise in the specific frequency range. An exact closed form relationship between bandwidthand output phase noise of the frequency synthesizer as well as the bandwidth-phase noise diagramis extracted by using this closed form relationship. From the analysis and simulation results, weobserve that the system has minimum phase noise at a particular closed-loop bandwidth. Tovalidate simulation results, the synthesizer is implemented on the low loss professional printedcircuit board (PCB). Measurement setup is scheduled on spectrum analyzer 8562A in the span of5MHz and 10MHz. These measurements show excellent results in output spectrum of thefrequency synthesizer.
Frequency synthesizers
phase noise
phase-locked loop
phase noise reduction
2014
06
01
21
32
http://ijste.shirazu.ac.ir/article_2096_8b256bf1cf8250a8acdd27631ba5defb.pdf
Iranian Journal of Science and Technology Transactions of Electrical Engineering
2228-6179
2228-6179
2014
38
E1
TWO-DIMENSIONAL ANALYTICAL MAGNETIC FIELD CALCULATIONS FOR DOUBLY-SALIENT MACHINES
This paper investigates a 2-dimensional (2-D) analytical magnetic field prediction fordoubly-salient machines. Using the subdomain technique, the effects of saliency on both the rotorand stator structures as well as their interactions are considered. The approach can be used formagnetic field calculation in machines with any combination of rotor- and stator-pole number.Three different stator winding structures are considered: non-overlapping winding with all teethwound, non-overlapping winding with alternate teeth wound and 2-layer overlapping winding. Toenable the analytical solution of the governing partial differential equations, the stator and rotoriron is assumed to be infinitely permeable and therefore the saturation effects are neglected. Theproposed approach is used in two case studies: (1) to calculate the armature reaction magnetic fielddistribution of a three-phase slotted brushless machine with surface inset magnets and (2) tocompute the magnetic field distribution of a four-phase switched reluctance motor. Note that theproposed approach cannot be employed in the case of machines with considerable saturationeffects. The analytical results are compared with those obtained from finite element analyses tovalidate the analytical calculations.
Subdomain
brushless machines
switched reluctance machine
surface inset magnet
2014
06
01
33
57
http://ijste.shirazu.ac.ir/article_2097_b408ace855d1dbf1ddafe437efd27f36.pdf
Iranian Journal of Science and Technology Transactions of Electrical Engineering
2228-6179
2228-6179
2014
38
E1
A NOVEL APPROACH TO MACHINE TRANSLATION: A PROPOSED LANGUAGE-INDEPENDENT SYSTEM BASED ON DEDUCTIVE SCHEMES
Compared to corpora-based machine translation methods, rule-based methods havedeficiencies, which make them unattractive for the researchers of this field. The first problem isthat these methods are language dependent. Rule-based methods require the syntactic informationabout source and target languages. On the other hand, in many cases, especially for proverbs andspecific expressions, syntactic rules are not useful anymore. In such cases, the use of examplebasedapproaches is inevitable. In this work, we propose and integrate a set of novel schemes tointroduce a new translation system, called BORNA. First a grammar induction method based onthe Expectation Maximization (EM) algorithm is proposed. After representing the extractedknowledge in the form of a set of nested finite automata, a recursive model is proposed, whichuses a combination of rule and example based techniques. In the translation phase, through ahierarchical chunking process, the input sentence is divided into a set of phrases. Each phrase issearched in the corpus of examples. If the phrase is found, it will not be chunked anymore.Otherwise, the phrase is divided into smaller sub-phrases. The simulation results show thatBORNA outperforms its counterparts, significantly. Compared to PARS, Frengly and Googletranslators, BORNA receives the highest Bleu scores for its translations, while it results in theminimum values for different error measures, including PER, TER and WER.
Machine translation
example-based
rule-based
corpora-based
finite automata
grammar induction
2014
06
01
59
72
http://ijste.shirazu.ac.ir/article_2098_1517d78d7d8823162a3ba11475f624c7.pdf
Iranian Journal of Science and Technology Transactions of Electrical Engineering
2228-6179
2228-6179
2014
38
E1
A COST EFFICIENT TWO-LEVEL MARKET MODEL FOR TASK SCHEDULING PROBLEM IN GRID ENVIRONMENT
This paper investigates the scheduling problem of independent tasks in market-basedgrids . The heterogeneity and autonomy of resources in grids highlight the need for more flexiblemodels and approaches to be exploited in these environments. To address this issue, a two-levelmarket model is presented in this paper to schedule tasks to the grid resources. In the proposedmodel , users submit their own tasks to a centralized resource manager named meta-scheduler .Meta-scheduler knows general information about each of the administrative domains , called sites ,existing in the low-level part of the model. Using the information gathered from all of the sites ,meta-scheduler selects more suitable sites to execute the tasks with the aim of minimizing theoverall cost of tasks execution . In this model, meta-scheduler not only targets the minimization ofoverall cost of the tasks execution, but also achieves this objective without any presumption aboutthe policies and algorithms implemented in the lower layers of the system which addresses thedynamicity of environment. In addition to the two-level market model , a new task schedulingalgorithm called GA-VNS which is an enhanced version of genetic algorithm is presented to beapplied in market-based grids. GA-VNS can be used by local schedulers in each site with thepolicy of cost minimization considering the makespan of the system as a second criterion. Theresults obtained from performance evaluation of GA-VNS and other well-known algorithms in thiscontext show that GA-VNS outperforms other algorithms in terms of the overall cost of tasksexecution .
Grid environment
scheduling algorithm
local search
execution cost
task deadline
2014
06
01
73
90
http://ijste.shirazu.ac.ir/article_2099_6db8c993cf940702ee82b864265c5a0c.pdf
Iranian Journal of Science and Technology Transactions of Electrical Engineering
2228-6179
2228-6179
2014
38
E1
THE PRINCIPAL COMPONENT INVERSE ALGORITHM FOR DETECTION IN THE PRESENCE OF REVERBERATION USING AUTOREGRESSIVE MODEL
Reverberation noise in active sonar leads to a very complicated situation for targetdetection. Reverberation is often modeled as the autoregressive model. In this paper, theautoregressive model is considered for reverberation and the Principal Component Inverse (PCI)algorithm is used to separate target echo signal from reverberation. This consideration helps us topropose a new method to improve computational complexity for the rank determination of theobservation matrix via singular value decomposition. It is shown that this new method is efficienton real data to separate target echo signal from reverberation.
Reverberation cancellation
autoregressive model
principal component inverse (PCI) algorithm
2014
06
01
91
97
http://ijste.shirazu.ac.ir/article_2100_b1aa88a809029eaaf842870e52e98ef2.pdf
Iranian Journal of Science and Technology Transactions of Electrical Engineering
2228-6179
2228-6179
2014
38
E1
BUILDING REPUTATION FOR SERVICE-ORIENTED AMI: MODELING, ALGORITHMS, AND ANALYSIS
Service reputation is a key factor for service selection and service composition inService-Oriented Ambient Intelligence systems. Hence, service reputation computing should fullyreflect the feature of multi-rating fusion and the utility value dynamic attenuation characters of therating. The paper combines D-S evidence theory with dynamic attenuation and puts forward aservice reputation computing algorithm based on multi-rating fusion, which is adapted to theAmbient Intelligence systems. First, a layered computing model of the service reputation is given.Then, a mechanism of dynamic attenuation based on time windows, an objective rating andadvertisement honesty rating of service, and a user credibility computing algorithm are presented.Afterward, the rating information is combined with the D-S evidence theory to raise anaggregation algorithm of the service general reputation for the Ambient Intelligence environments.Finally, a prototype test is carried out to verify the effectiveness and availability of the modeltogether with the algorithms.
Service reputation
trust
evidence theory
AmI
2014
06
01
99
109
http://ijste.shirazu.ac.ir/article_2101_84e0a210ed07698a9a68d1243f85afa7.pdf