Different Number Of Iterations Research Articles

Ber Analysis of Turbo Code Interleaver

This paper presents a low complexity interleaver design that facilitates high throughput Turbo decoding required for next generation wireless systems. When a parallel decoder structure is considered, interleaver design is the most important issue. In such parallel decoder, the contention problem occurs when more than one extrinsic value references to the same memory block for read or write purpose. This paper focuses on the alternate method for QPP interleaver which shows improved BER performance for large frame size. Bit reversed indexing is used to generate interleaved addresses. A counter is used to generate sequential address as well as interleaved address. The number of address lines of memory which stores data , depends upon frame size of data. In this paper, a comparison is made between best proved interleaver and proposed interleaver on the basis of BER performance for different number of iterations, different frame size and different decoding algorithms. General Terms Interleaver, Turbo Decoder, Bit reverse indexing.

Multi objective optimization of horizontal axis tidal current turbines, using Meta heuristics algorithms

The performance of horizontal axis tidal current turbines (HATCT) strongly depends on their geometry. According to this fact, the optimum performance will be achieved by optimized geometry. In this research study, the multi objective optimization of the HATCT is carried out by using four different multi objective optimization algorithms and their performance is evaluated in combination with blade element momentum theory (BEM). The second version of non-dominated sorting genetic algorithm (NSGA-II), multi objective particle swarm optimization algorithm (MOPSO), multi objective cuckoo search algorithm (MOCS) and multi objective flower pollination algorithm (MOFPA) are the selected algorithms. The power coefficient and the produced torque on stationary blade are selected as objective functions and chord and twist distributions along the blade span are selected as decision variables. These algorithms are combined with the blade element momentum (BEM) theory for the purpose of achieving the best Pareto front. The obtained Pareto fronts are compared with each other. Different sets of experiments are carried out by considering different numbers of iterations, population size and tip speed ratios. The Pareto fronts which are achieved by MOFPA and NSGA-II have better quality in comparison to MOCS and MOPSO, but on the other hand a detail comparison between the first fronts of MOFPA and NSGA-II indicated that MOFPA algorithm can obtain the best Pareto front and can maximize the power coefficient up to 4.3% and the produced torque on stationary blade up to 57.9%. The geometries of the first and last members of the Pareto front of MOFPA are compared to each other. These members which produce the maximum power coefficient and the maximum produced torque on stationary blade have hyperbolic and constant chord distributions, respectively.

Designing of Log Periodic Antenna using Fractal Koch

In this paper, a log periodic fractal Koch antenna is proposed. The antenna is an amalgamation of log periodic antennas that require large lengths and fractal curves that are known for excellent form factor characteristics. The procedure is to design the LPFKA with three different numbers of iterations for better appraisal. The Zeland IE3D software has been used to analyze the performances of the designed antennas such as return loss, radiation patterns and gain. The antennas have been fabricated using FR4 laminate board thickness 1.6 mm and relative permittivity of 4.4 and mounted above the ground plane at a height of 6 mm. Using fractal Koch technique, the return loss of the antenna can be reduced up to 72% when the series iteration is applied to the antennas without degrading the overall performances.

Usefulness of the Chang attenuation correction method with use of a CT-based μ map by FBP reconstruction in 201Tl SPECT-MPI

Attenuation correction (AC) on nuclear images of non-uniform domains is generally performed by a change of the computed tomography (CT) values to μ values, which are then inserted as components into the detection probability of iterative reconstruction techniques (OS-EM Iterative AC). We established an AC technique which uses a CT μ map based on the Chang AC. Our purpose in this study was to confirm the appropriateness of the Chang AC with the OS-EM and the FBP method (OS-EM Chang AC and FBP Chang AC) by evaluating the results obtained in a phantom and clinical study for (201)Tl single-photon emission-computed tomography-myocardial perfusion imaging (SPECT-MPI). Myocardial phantom study and retrospective clinical study were performed. Evaluations for image quality (uniformity and contrast) and image quantitative values [accurate left ventricular (LV) volume and radioactivity] were performed for both studies. FBP Chang AC showed good image uniformity and proper contrast in phantom and clinical study. Accurate LV volume and radioactivity in the myocardium were also obtained by the phantom study. On the other hand, the number of iterations influenced the image quality both in OS-EM Iterative AC and OS-EM Chang AC in the phantom study. Different numbers of iterations were necessary for obtaining good contrast ratio in each of the anterior and inferior wall, and accurate LV volume. The number of iterations influences the image quality and quantitative values on OS-EM Iterative Chang AC and OS-EM Chang AC images. In addition, it is difficult to set an appropriate number of iterations for the iterative reconstruction of these images in phantom and clinical studies. Therefore, FBP Chang AC is considered to be clinically useful.

0217 シェルピンスキー四面体を通して生成される乱流の指数関数減衰領域の乱流特性

In the decay of turbulence generated by passing through Sierpinski tetrahedron, there exists a region in accordance with the exponetial law, without obeying the power law. In this study, mechanism of exponential decay is investigated by measuring the profile of velocity statistics over the cross section. Mean velocity profiles are similar to each other amongst the structures with different number of iteration (N=2, 3, 4) and so are turbulence intensities except the case for the least number (N=2).

A System Supporting Qualitative Research

this paper presents a system aimed to be entirely located in the Internet. The database, server side, logic and user interface are accessible regardless the location and equipment of the working team members. The system supports qualitative analysis of large datasets, and the work can be distributed among several team members or teams. A modified mixed method for developing software projects is used, according to the peculiarities of our case, splitting the phase of code writing into two sub-phases each with different number of iterations.

Multiband fractal based reconfigurable antenna with introduction of RF MEMS switches for next generation devices

Next generation network’s main requirements are compact size and also support to heterogeneous network. Fractal antennas have useful applications in cellular telephone and microwave communications. Video conferencing, streaming video are main applications that are included in next generation networks and requirements for these applications are high data rates require to have high bandwidth. But as size of antenna reduces, bandwidth support also reduces. So it is required to have small size with high bandwidth. Fractal antennas are proposed in this paper for different applications as it is compact and also has good bandwidth. In this paper, we propose a reconfigurable fractal shape antenna for Ku and Ka band. Its performance analysis shows these antennas are multiband antennas support Ku and Ka bands and also support mobile terminal applications which are sight to be used in next generation networks. Different number of iteration is performed for its support to different bands. Re-configurability in antenna is another important concept and in this work; the reconfigurability is achieved by using radio frequency microelectromechanical system (RF MEMS) switches. Key words: Meander, RF MEMS switch, reconfigurable antenna, fractal antenna.

Segmentation of Assamese phonemes using hybrid soft-computational approach

Phonemes are the smallest distinguishable unit of speech signal. Segmentation of a phoneme from its word counterpart is a fundamental and crucial part in speech processing because an initial phoneme is used to activate words starting with that phoneme. This work describes an artificial neural network-based algorithm developed for segmentation and classification of consonant phoneme of the Assamese language. The algorithm uses weight vectors, obtained by training self-organising map (SOM) with different number of iterations, as a segment of different phonemes constituting the word whose linear prediction coefficients samples are used for training. The algorithm shows an abrupt rise in success rate than the conventional discrete wavelet-based speech segmentation. A two-class probabilistic neural network problem carried out with clean Assamese phoneme is used to identify phoneme segment. The classification of the phoneme segment is alone as per the consonant phoneme structure of the Assamese language which consists of six phoneme families. Experimental results establish the superiority of the SOM-based segmentation over the discrete wavelet transform-based approach.

Evaluation of strategies towards harmonization of FDG PET/CT studies in multicentre trials: comparison of scanner validation phantoms and data analysis procedures

PET quantification based on standardized uptake values (SUV) is hampered by several factors, in particular by variability in PET acquisition settings and data analysis methods. Quantitative PET/CT studies acquired during a multicentre trial require harmonization of imaging procedures to maximize study power. The aims of this study were to determine which phantoms are most suitable for detecting differences in image quality and quantification, and which methods for defining volumes of interest (VOI) are least sensitive to these differences. The most common accreditation phantoms used in oncology FDG PET/CT trials were scanned on the same scanner. These phantoms were those used by the Society of Nuclear Medicine Clinical Trials Network (SNM-CTN), the European Association of Nuclear Medicine/National Electrical Manufacturers Association (EANM/NEMA) and the American College of Radiology (ACR). In addition, tumour SUVs were derived from ten oncology whole-body examinations performed on the same PET/CT system. Both phantom and clinical data were reconstructed using different numbers of iterations, subsets and time-of-flight kernel widths. Subsequently, different VOI methods (VOI(A50%), VOI(max), VOI(3Dpeak), VOI(2Dpeak)) were applied to assess the impact of changes in image reconstruction settings on SUV and recovery coefficients (RC). All phantoms demonstrated sensitivity for detecting changes in SUV and RC measures in response to changes in image reconstruction settings and VOI analysis methods. The SNM-CTN and EANM/NEMA phantoms showed almost equal sensitivity in detecting RC differences with changes in image characteristics. Phantom and clinical data demonstrated that the VOI analysis methods VOI(A50%) and VOI(max) gave SUV and RC values with large variability in relation to image characteristics, whereas VOI(3Dpeak) and VOI(2Dpeak) were less sensitive to these differences. All three phantoms may be used to harmonize parameters for data acquisition, processing and analysis. However, the SNM-CTN and EANM/NEMA phantoms are the most sensitive to parameter changes and are suitable for harmonizing SUV quantification based on 3D VOIs, such as VOI(A50%) and VOI(3Dpeak), and VOImax. Variability in SUV quantification after harmonization could be further minimized using VOI(3Dpeak) analysis, which was least sensitive to residual variability in image quality and quantification.

Design of a new interleaver using cross entropy method for turbo coding

The main aim of this work is to find a way to improve a turbo code performance by designing a new interleaver structure based on the cross entropy (CE). The goal is to compare the performance of the CE method to a more popular interleaver such as the dithered golden interleaver. This study describes the performance of the turbo code – binary phase shift keying (BPSK) modem which was designed at the Instrumentation Division, Centre of Space Techniques. The simulation results are detailed in terms of the optimal solution observed along with the estimated bit-error rate against Eb /N 0. The authors compare the performance of turbo codes for different interleaver sizes and different number of iterations (resulting trade-off curves) assuming two channel types (Gaussian and Rayleigh channels). For the simulated cases of the interleavers, good performance is obtained with the CE interleaver when transmitting data both in short block length (N = 400 bits), and long block length (N = 1024).

Loop Transparency for Scalable Dynamic Symbolic Execution

Dynamic symbolic execution is a promising approach for software analyzing and testing. However, it fails to scale to large programs due to the exponential number of paths to be explored. This paper focus on tackling loop caused path explosion problems and proposes a new approach to reduce paths that produce the same effects. We present a loop transparency strategy that makes use of the decision graph of under test program to discard constraints that produce paths with only a different number of iterations. A dynamic software testing tool LTDse based on loop transparency is designed and evaluated on three benchmarks. The experimental results show that our approach is effective since it can achieve better code coverage or require fewer program executions than traditional strategies.

OFDM–IDMA for Uplink Transmission in Passive Optical Networks

In this paper, we propose the orthogonal frequency-division multiplexing-interleaved division multiplexing access (OFDM-IDMA) technique for passive optical networks (PONs). We evaluate the performance of such systems and compare it with the already proposed OFDM-Access (OFDMA) technique by means of the bit error rate versus received power for two different coding schemes and different number of iterations. Results show that OFDM-IDMA technique with an unequal power allocation distribution among the different optical network units (ONUs) offers similar performance to OFDMA when used with a simple convolutional code at an aggregated rate of 4 and 8 Gbits/s. Dynamic bandwidth allocation can be easily implemented with this technique.

Optimization of Radiant Heater Power for Heating of Flat Plates Using Metaheuristic Methods

In this article, simulated annealing (SA), genetic algorithm (GA), and tabu search (TS) methods are employed separately and together for finding optimal radiant heater settings for obtaining a specific temperature profile on a design surface. Results show that all methods yield to very acceptable results for various desired temperature profiles but after different number of iterations. The GA and TS methods progress very rapidly before slowly stabilizing after a certain number of iterations, while the SA method progresses for longer periods. In addition, hybrid combinations of GA, SA, and TS proved to be better than separate ones.

Feedforward Neural Network Trained by BFGS Algorithm for Modeling Plasma Etching of Silicon Carbide

Electron cyclotron resonance (ECR) plasma etching of silicon carbide is numerically modeled by a feedforward neural network (FNN), which is trained by the Broyden, Fletcher, Goldfarb, and Shanno (BFGS) optimization algorithm and the conventional backpropagation (BP) algorithm. The training samples are obtained from our experimental results, which meet the requirement of Box-Wilson central-composite-designed experimental test design. By using the samples, the BFGS algorithm is compared with the conventional BP algorithm with different hidden neuron numbers, different number of iterations and various learning rates. It is shown that the BFGS algorithm requires less hidden neurons and less iteration to obtain the same training results, and it also provides much smaller cross-validation errors. Therefore, the FNN trained by the BFGS algorithm possesses much better approximation and generalization ability. The silicon carbide ECR process modeling results demonstrate that the FNN trained by the BFGS algorithm are fast, reliable, and accurate.

LOG PERIODIC FRACTAL KOCH ANTENNA FOR UHF BAND APPLICATIONS

In this paper, the design of Log Periodic Fractal Koch Antennas (LPFKA) is proposed for Ultra High Frequency (UHF) band applications. The procedure to design the LPFKA with three different numbers of iterations in order to reduce the antenna size is discussed. The Computer Simulation Technology (CST) software has been used to analyze the performances of the designed antennas such as return loss, radiation patterns, current distribution and gain. The antennas have been fabricated using FR4 laminate board with wet etching technique. Using fractal Koch technique, the size of the antenna can be reduced up to 27% when the series iteration is applied to the antennas without degrading the overall performances. Both simulated and measured results are compared, analyzed and presented in this paper.

Iterated rippled noise discrimination at long durations

Iterated rippled noise (IRN) was used to study discrimination of IRN stimuli with a lower number of iterations from IRN stimuli with a higher number of iterations as a function of stimulus duration (100-2000 ms). Such IRN stimuli differ in the strength of the repetition pitch. In some cases, the gain used to generate IRN stimuli was adjusted so that both IRN stimuli in the discrimination task had the same height of the first peak in the autocorrelation function or autocorrelogram. In previous work involving short-duration IRN stimuli (<500 ms), listeners were not able to discriminate between IRN stimuli that had different numbers of iterations but the same height of the first peak in the autocorrelation function. In the current study, IRN discrimination performance improved with increases in duration, even in cases when the height of the first peak in the autocorrelation was the same for the two IRN stimuli. Thus, future studies involving discrimination of IRN stimuli may need to use longer durations (1 s or greater) than those that have been used in the past.

Source level merging of independent programs

In here we describe a technique to merge at source level two (and hence more) independent C programs. Due to the independence of the programs, the merged program has more parallelism that can be extracted by the underlying compiler and CPU. Thus it is expected that the execution time of the merged program will be better than the time obtained by executing the two programs separately. The usefulness of such merging for embedded systems has been studied and demonstrated by the works of Dean and others with the Thrint compiler for merging threads at Assembly level. The main contribution of this work is an efficient algorithm for matching sub-components considering the inside structure of the sub-components and not only their execution frequency. Two novel techniques for balancing the merge of sub-components are presented: • Residual loop merging (RLM) as a way to merge loops with different nesting and execution frequency levels. • Using the remaining iterations formed after merging two non-equal loops (loops with different number of iterations) in future mergings of other loops. These two abilities allow the proposed algorithm to simplify the matching process and overcome merging problems related to deep nested structure. We also consider the problem of merging function calls and make extensive use of cloning (and not only inlining as is the case with previous works). The final tool is the first complete system for merging C-programs at source level supporting profile and structure based matching. The main use of merging is to speed up embedded systems that usually execute independent threads or processes that can potentially be merged. Our experimental results suggest that the proposed merging technique can speedup the execution of two independent programs by 10%–20% for about half of mergings that have been tested.

Loudness in relation to iterated rippled noise

This study examined the loudness of iterated rippled noises (IRNs) with different number of iterations under conditions of equal sound pressure. The scale values of loudness were obtained using a paired–comparison method. The results showed that the loudness of IRNs was not constant, even though the sound pressure level was equivalent. The loudness of IRNs increased with increasing iteration number. This indicated that repetitive components of sounds might affect their loudness.

A novel fractal microstrip PBG structure

AbstractA novel fractal microstrip PBG structure is proposed. It is realized by replacing the etched rectangular holes in a ground plane with a Sierpinski carpet. A dual‐stopband characteristic not related to harmonics is observed. Different numbers of iterations of Sierpinski carpet are studied experimentally. © 2002 John Wiley &amp; Sons, Inc. Microwave Opt Technol Lett 32: 136–138, 2002.

Resolution recovery for list-mode reconstruction in SPECT

The purpose of the study was to evaluate the resolution recovery in thelist-mode iterative reconstruction algorithm (LMIRA) for SPECT. In this studywe compare the performance of the proposed method with other iterativeresolution recovery methods for different noise levels. We developed aniterative reconstruction method which uses list-mode data instead of binneddata. The new algorithm makes use of a more accurate model of the collimatorstructure. We compared the SPECT list-mode reconstruction with MLEM, OSEM andRBI, all including resolution recovery. For the evaluation we used Gaussianshaped sources with different FWHM at three different locations and threenoise levels. For these distributions we calculated the reconstructed imagesfor a different number of iterations. The absolute error for the reconstructedimages was used to evaluate the performance. The performance of all fourmethods is comparable for the sources located in the centre of the field ofview. For the sources located out of the centre, the error of the list-modemethod is significantly lower than that of the other methods. Splitting thesystem model into a separate object-dependent and detector-dependent modulegives us a flexible reconstruction method. With this we can very easily adaptthe resolution recovery to different collimator types.