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Issue Info: 
  • Year: 

    2005
  • Volume: 

    3
  • Issue: 

    1
  • Pages: 

    52-58
Measures: 
  • Citations: 

    0
  • Views: 

    985
  • Downloads: 

    0
Abstract: 

In this paper, we propose a new model for additive noise based on GARCH time-series in Array signal processing. Due to the some reasons such as complex implementation and computational problems, probability distribution function of additive noise is assumed Gaussian. In the different applications, scrutiny and measurement of noise shows that noise can sometimes significantly non-Gaussian and thus the methods based on Gaussian noise will degrade in an actual conditions. Heavy-tail probability density function (PDF) and time-varying statistical characteristics (e.g.; variance) are the most features of the additive noise process. On the other hand, GARCH process has important properties such as heavy-tail PDF (as excess kurtosis) and volatility modeling through feedback mechanism onto conditional variance so that it seems the GARCH model is a good candidate for the additive noise model in the Array processing applications. In this paper, we propose a new method based on GARCH using the maximum likelihood approach in Array processing and verify the performance of this approach in the estimation of the Direction-of-Arrivals of sources against the other methods and using the Cramer-Rao Bound.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

AMIRI H. | NASERI M.

Issue Info: 
  • Year: 

    2019
  • Volume: 

    6
  • Issue: 

    3 (17)
  • Pages: 

    27-42
Measures: 
  • Citations: 

    0
  • Views: 

    874
  • Downloads: 

    0
Abstract: 

Beamforming is one of the most important Array signal processing blocks in sonar systems which due to the nature of the environment and conditions of operating, requires using of the robust and adaptive methods to provide the feasible specifications in outputs. In the present paper, the latest methods for the adaptive robust beamforming such as enhanced and modified covariance matrix methods are investigated and finally, by using of simulation in different scenarios and conditions such as steering vector error, sensors gain and phase perturbation and high power noise and strong interference, their capabilities and abilities are presented and method are evaluated. The results show that the methods of Diagonal Loading, LCMV and LCMV mod in different states are not feasible and CMR and ESB methods in the presence of error of steering vector, strong interference and high power noise and gain and phase distortion are more suitable.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

DIAMANTARAS I. | KUNG S.Y.

Issue Info: 
  • Year: 

    1997
  • Volume: 

    17
  • Issue: 

    1
  • Pages: 

    43-55
Measures: 
  • Citations: 

    1
  • Views: 

    124
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

LEV ARI H.

Issue Info: 
  • Year: 

    2005
  • Volume: 

    5
  • Issue: 

    -
  • Pages: 

    123-130
Measures: 
  • Citations: 

    1
  • Views: 

    186
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2024
  • Volume: 

    13
  • Issue: 

    25
  • Pages: 

    126-144
Measures: 
  • Citations: 

    0
  • Views: 

    16
  • Downloads: 

    0
Abstract: 

In this paper, an alternative approach in operational modal analysis is presented, utilizing image processing technique and transmissibility functions. Imaging sensors do not impose additional mass on the structure due to their non-contact nature, while transmissibility functions, independent of excitation type, can directly extract mode shapes. The innovation of this research lies in combining these two techniques to record dynamic responses and identify modal properties. To capture the temporal response history from video signals, the block-matching method with sub-pixel accuracy was employed. Validation was conducted by recording the response of the tip of a cantilevered steel beam subjected to impact excitation, using a high-speed camera and a laser vibrometer, simultaneously. The RMSE plots in the time domain and the PSD in the frequency domain indicate high accuracy of this method. Using this approach, the displacement time histories of various points on the structure were extracted from the video signals, and the modal properties, including natural frequencies, damping ratios, and mode shapes, were identified using the transmissibility matrix method. The results obtained from the proposed method were compared with the stochastic subspace identification (SSI) method and analytical solutions. The findings reveal the accuracy of the modal identification approach introduced in this article. The highest relative error in estimating the natural frequencies of the first and second modes, compared to the values from the laser method, are 0.19% and 0.13%, respectively, and in comparison to the analytical values, they are 0.34% and 1.5%, respectively.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2024
  • Volume: 

    13
  • Issue: 

    25
  • Pages: 

    93-125
Measures: 
  • Citations: 

    0
  • Views: 

    19
  • Downloads: 

    0
Abstract: 

In traditional speech processing, feature extraction and classification were conducted as separate steps. The advent of deep neural networks has enabled methods that simultaneously model the relationship between acoustic and phonetic characteristics of speech while classifying it directly from the raw waveform. The first convolutional layer in these networks acts as a filter bank. To enhance interpretability and reduce the number of parameters, researchers have explored the use of parametric filters, with the SincNet architecture being a notable advancement. In SincNet's initial convolutional layer, rectangular bandpass filters are learned instead of fully trainable filters. This approach allows for modeling with fewer parameters, thereby improving the network's convergence speed and accuracy. Analyzing the learned filter bank also provides valuable insights into the model's performance. The reduction in parameters, along with increased accuracy and interpretability, has led to the adoption of various parametric filters and deep architectures across diverse speech processing applications. This paper introduces different types of parametric filters and discusses their integration into various deep architectures. Additionally, it examines the specific applications in speech processing where these filters have proven effective.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2006
  • Volume: 

    8
  • Issue: 

    2 (30)
  • Pages: 

    14-18
Measures: 
  • Citations: 

    0
  • Views: 

    1310
  • Downloads: 

    0
Abstract: 

BACKGROUND AND OBJECTIVE: Varicocele is one of the causes of male infertility. It changes with temperature and drainage of testicular veins that due to spermatogenesis disturbance and decrease of fertility in these patients. However varicocelectomy is a treatment for varicocele, but there are other methods of treating this disease including assisted reproductive technology (ART), Sperm processing and swim up. METHODS: This interventional study was performed on 155 cases in fertility and infertility Center of Babol University of medical sciences in 2004. Sperm parameters in varicocele patients was assessed before and after sperm processing. FINDINGS: The mean age of patients was 31.8 years. Sperm motility before sperm processing in grade III and IV was 53.9% and 12.9%, respectively but after sperm processing in grade III and IV changed to 78.7% and 56.8%, respectively. Total motility before sperm processing was 40 % and changed after processing to 80%. CONCLUSION: The results show that with sperm processing and collection of appropriate sperms, we are able to increase fertility.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Journal: 

AMIRKABIR

Issue Info: 
  • Year: 

    2004
  • Volume: 

    15
  • Issue: 

    59-A
  • Pages: 

    14-28
Measures: 
  • Citations: 

    0
  • Views: 

    1090
  • Downloads: 

    0
Abstract: 

MUSIC (Multiple Signal Classification) algorithm as a base of Sub-Space algorithms is applied in Array processing systems. The error of the algorithm in detection & resolution depends on several parameters, such as snapshots, signal-to-noise ratio and sensor locations. In this paper, the previous dependency is investigated. So, all the scenarios of Array shapes are defended and then i analytic formulas are derived in two bearings of θ and φ We will show which parameters have ithe most effect on the desired error (the error threshold).

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Author(s): 

SADEGHI HAMED | AKHAVAN AMIR

Issue Info: 
  • Year: 

    2018
  • Volume: 

    14
  • Issue: 

    4 (SERIAL 34)
  • Pages: 

    19-29
Measures: 
  • Citations: 

    0
  • Views: 

    592
  • Downloads: 

    0
Abstract: 

Nowadays، several infrastructure-based low-frequency acoustical sensor networks are employed in different applications to monitor the activity of diverse natural and man-made phenomena، such as avalanches، earthquakes، volcanic eruptions، severe storms، super-sonic aircraft flights، etc. Two signal detection methods are usually implemented in these networks for the purpose of event occurrence identification، which are the progressive multi-channel correlator (PMCC) and the so-called Fisher detector. But، the Fisher method is more important and applicable in low signal-to-noise (SNR) ratio conditions، which is of a special interest in acoustical monitoring networks. Unfortunately، an important disadvantage of this algorithm is its relative high detection-time; which limits its application for real-time detection scenarios. This disadvantage is fundamentally due to a beam forming process in Fisher algorithm، which requires doing complete search in a slowness-network، constructed from possible incoming wave front directions and speeds. To address this issue، we propose a method for implementation of this beam forming on a graphics processing unit (GPU)، in order to realize a fast-computing and/or near real-time signal processing technique. In addition، we also propose a parallel-processing algorithm for further enhancement of the performance of this GPU-based Fisher detector. Simulation results confirm the performance improvement of Fisher detector، in terms of required processing time for acoustical signal detection applications.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2006
  • Volume: 

    8
  • Issue: 

    3 (31)
  • Pages: 

    178-183
Measures: 
  • Citations: 

    0
  • Views: 

    1257
  • Downloads: 

    272
Abstract: 

Introduction: Colorectal Carcinoma is a main health problem in many countries and the third common cancer in Iran. This malignancy at present is the most curable carcinoma of gastrointestinal tract. Variation in the expression of the proteins produced by P53, P21, P16, E-cadherin, and β-catenin genes have been noted in this malignancy and may be important in the prognosis and therapeutic response rate. The aim of this study was to compare the frequency and pattern of expression of these proteins in tumoral and nontumoral colonic mucosa. The correlation with prognostic factors including tumor stage, grade, and vascular and perineural invasion was also determined. Material and Methods: The paraffin blocks from tumoral and nontumoral parts of the colon obtained from 58 patients with colorectal adenocarcinoma were studied along with 50 colectomic cases in individuals without malignancy. Cylindrical tissue fragments were obtained from appropriate parts of donor blocks by using a 2.5 mm punch biopsy instrument. Each 30 samples were manually Arrayed in one tissue Array block. Expression of above genes was investigated after sectioning the blocks and immunohistochemical staining of slides. Results: The expression of P53 in tumor cells was significantly more common than in colonic nontumor cells and colon of individuals without tumor (p<0.001); expression of this protein in tumoral tissues was directly related to vascular invasion (p=0.017). The expression frequency of P21 and P16 in tumor cells was less than nontumoral tissues of patients with cancer and patients without cancer (p<0.001). These two gene products showed no correlation with prognostic factors. The expression frequency of membranous E-cadherin and β-catenin in tumor cells was not different from controls, while the membranous expression of E-cadherin was inversely related to cell differentiation (p=0.023) and vascular invasion (p=0.025). In addition, the membranous expression of β-catenin was inversely related to vascular invasion (p=0.049). Cytoplasmic and nuclear expression of β-catenin in tumor cells were significantly higher than their expression in the controls (p<0.001). Cytoplasmic expression of this marker was inversely related to disease stage (p=0.013), while its nuclear expression was inversely related to cell differentiation (p=0.012).Conclusion: According to our data, it seems that we are able to predict aggressive capacity of the colorectal tumor by determining the frequency and pattern of expression of P53, E-cadherin and β-catenin proteins. These studies can be done simply on formalin-fixed small biopsy samples before surgery to provide valuable information for surgeons, gastroenterologists, and oncologists to choose the best therapeutic approach and predict the therapeutic response. Manual tissue Array method is believed to be an economical technique for similar research projects.

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