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اطلاعات دوره: 
  • سال: 

    1397
  • دوره: 

    15
  • شماره: 

    3 ( پیاپی 37)
  • صفحات: 

    113-122
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    879
  • دانلود: 

    172
چکیده: 

سیگنال های صوتی دیجیتال، به دلیل این که حاوی نرخ اطلاعات زیادی هستند، پوشش مناسبی برای روش های نهان نگاری محسوب می شوند. روش های متنوعی برای نهان نگاری داده های مختلف و به تبع آن نهان کاوی داده ها در سیگنال صوتی وجود دارد. در این میان روش های نهان کاوی فراگیر به دلیل عدم وابستگی به الگوریتم نهان نگاری، کاربرد وسیع تری دارند. در این مقاله روش جدیدی برای نهان کاوی فراگیر ارائه شده که در آن با به کارگیری ضرایب مربوط به همبستگی بین فریم، دقت نهان کاوی به مقدار قابل توجهی افزایش پیدا کرده است. همچنین عملکرد ماشین بردار پشتیبان با به کارگیری الگوریتم کاهش بازگشتی ویژگی ها به همراه کاهش بایاس ناشی از همبستگی بین آن ها بهبود یافته که منجر به افزایش پایداری نهان کاوی و دقت بیشتر شده است.

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اطلاعات دوره: 
  • سال: 

    2025
  • دوره: 

    13
  • شماره: 

    51
  • صفحات: 

    165-176
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    0
  • دانلود: 

    0
چکیده: 

This research used modern machine learning ways to predict the stages of primary biliary cholangitis using data from the Mayo Clinic trial. The research aims to obtain high prediction accuracy while representing balanced evaluation metrics. Important techniques include automated hyperparameters optimization with Optuna and Recursive Feature Elimination to improve model performance. Pre-processing included handling missing values, encoding of categorical features, and addressing class imbalances using SMOTE. A total of twelve machine learning algorithms are evaluated with ensemble-based models such as CatBoost and Extra Trees producing much better results. Evaluation metrics take into account all model predictions, including accuracy, precision, recall, F1 score, and ROC-AUC for performing balanced and interpretative evaluations of performances critical for imbalanced datasets. This endeavor includes clinical and laboratory information illustrating the prospect of machine learning in advancing therapeutic diagnosis, emphasizing the rigor and robustness in evaluation laid groundwork for future research to encompass even more generalizable and robust diagnostic tools.

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اطلاعات دوره: 
  • سال: 

    1404
  • دوره: 

    5
  • شماره: 

    1
  • صفحات: 

    93-110
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    44
  • دانلود: 

    0
چکیده: 

قیمت کمک هزینه اتحادیه اروپا یک راهکار به منظور مدیریت انتشار گازهای گلخانه ای می باشد، عوامل بسیاری نظیر شاخص های اقتصادی، مالی، سیاسی و ... می تواند بر آن اثرگذار باشد. پژوهش پیش رو در نظر دارد تا میزان اثرگذاری 31 شاخص مختلف انرژی، مالی و کالاهای اساسی را بر آن بررسی نماید. ازاین رو با یک استفاده روش ترکیبی داده محور به بررسی این امر می پردازد. در ابتدا با استفاده از الگوریتم میانگین متحرک یکپارچه خود رگرسیون به پاک سازی داده های مربوط به آن می پردازد و پس ازآن با روش تجزیه حالت متغیر بخش های مختلف این شاخص ها را تجزیه می نماید و یک سری مد ذاتی به دست می آورد، پس ازآن این مدها در سه مقیاس زمانی کوتاه مدت، میان مدت و بلندمدت قرار می گیرند، سپس با استفاده از ادغام حذف بازگشتی ویژگی ها و جنگل تصادفی با در نظر گرفتن اعتبارسنجی متقابل اقدام به انتخاب بهترین ویژگی ها در این سه مقیاس گرفته می شود. نتایج به دست آمده نشان می دهد در مقیاس زمانی میان مدت و بلندمدت، مدل موفق به پیش بینی با دقت بیشتر می باشد و پیش بینی نوسانات قیمت کمک هزینه اتحادیه اروپا با استفاده از این رویکردهای ترکیبی، می تواند به تصمیم گیری های دقیق تر و به موقع درزمینه سیاست گذاری و سرمایه گذاری کمک کند.

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

ZAYED E.M.E. | EL MONEAM M.A.

اطلاعات دوره: 
  • سال: 

    2010
  • دوره: 

    36
  • شماره: 

    1
  • صفحات: 

    103-115
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    425
  • دانلود: 

    0
چکیده: 

Our main objective is to study some qualitative behavior of the solutions of the difference equation xn+1 = gxn−k + (axn + bxn−k) / (cxn − dxn−k), n = 0, 1, 2, ..., where the initial conditions x−k,..., x−1, x0 are arbitrary positive real numbers and the coefficients, a, b, c and d are positive constants, while k is a positive integer number.

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

بازدید 425

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نویسندگان: 

FRANCESCONI E. | FRASCONI P. | GORI M.

اطلاعات دوره: 
  • سال: 

    1998
  • دوره: 

    1389
  • شماره: 

    -
  • صفحات: 

    104-117
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    187
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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

بازدید 187

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نویسندگان: 

SHOJAEDINI SEYED VAHAB | Adeli Maryam

اطلاعات دوره: 
  • سال: 

    2020
  • دوره: 

    7
  • شماره: 

    1
  • صفحات: 

    42-51
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    131
  • دانلود: 

    0
چکیده: 

Introduction: P300 speller is a kind of Brain-Computer Interface (BCI) system in which the user may type words by using the responses obtained from human focus on different characters. The high sensitivity of brain signals against noise in parallel with the similarity of responses obtained from the user focus on different characters makes it difficult to classify the characters based on their respective P300 wave. On the other hand, all areas of the brain does not carry useful P300 information. Methods: In this study, a new method is proposed to improve the performance of speller system which is based on selecting optimal P300 channels. In the proposed method, recursive elimination algorithm is presented for channel optimization, which utilizes deep learning concept (e. g. Convolutional Neural Network) as its cost function. The proposed method is examined on a data set from EEG signals recorded in a P300 speller system, including 64 different channels of responses to 29 characters. Then, its performance is compared with some existing methods. Results: The obtained results showed the ability of the proposed method in recognizing the characters in such way that it could accurately (i. e. 97. 34%) detect 29 characters by using only 24 out of all 64 electrodes. Conclusion: Applying the proposed method in speller systems led to considerable improvement in classification of characters compared to its alternatives. Several experiments proved that utilizing the proposed scheme may increases the accuracy almost 12. 9 percent compared to non-optimized case in parallel with reduction of the number of involved channels by approximately 1/3. Based on these results, the proposed method may be considered as an effective choice for application in P300 speller systems, thanks to reduction of the complexity of the system which is caused by the reduced number of channels and, on the other hand, due to its potential in increasing the accuracy of character recognition.

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

Rafiee A. | Moradi P. | Ghaderzadeh A.

اطلاعات دوره: 
  • سال: 

    1400
  • دوره: 

    51
  • شماره: 

    4
  • صفحات: 

    443-454
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    218
  • دانلود: 

    37
چکیده: 

Multi-label classification aims at assigning more than one label to each instance. Many real-world multi-label classification tasks are high dimensional, leading to reduced performance of traditional classifiers. Feature selection is a common approach to tackle this issue by choosing prominent features. Multi-label feature selection is an NP-hard approach, and so far, some swarm intelligence-based strategies and have been proposed to find a near optimal solution within a reasonable time. In this paper, a hybrid intelligence algorithm based on the binary algorithm of particle swarm optimization and a novel local search strategy has been proposed to select a set of prominent features. To this aim, features are divided into two categories based on the extension rate and the relationship between the output and the local search strategy to increase the convergence speed. The first group features have more similarity to class and less similarity to other features, and the second is redundant and less relevant features. Accordingly, a local operator is added to the particle swarm optimization algorithm to reduce redundant features and keep relevant ones among each solution. The aim of this operator leads to enhance the convergence speed of the proposed algorithm compared to other algorithms presented in this field. Evaluation of the proposed solution and the proposed statistical test shows that the proposed approach improves different classification criteria of multi-label classification and outperforms other methods in most cases. Also in cases where achieving higher accuracy is more important than time, it is more appropriate to use this method.

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اطلاعات دوره: 
  • سال: 

    2016
  • دوره: 

    5
  • شماره: 

    1
  • صفحات: 

    65-78
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    232
  • دانلود: 

    0
چکیده: 

In this paper it has been attempted to investigate the capability of the consumption-based capital asset pricing model (CCAPM), using the general method of moment (GMM), with regard to the Epstien-zin recursive preferences model for Iran's capital market. Generally speaking, recursive utility permits disentangling of the two psychologically separate concepts of risk aversion and elasticity of intertemporal substitution which are constrained to be equal to the inverse of each other for the traditional time-additive utility functions. Rather than using the stock market as a proxy for wealth, we constructed a more comprehensive return which is the weighted average of stock index return, labor wage growth (as a proxy for human capital return), housing return and deposit return. The empirical results demonstrate that the signs of the coefficient of the relative risk aversion and the intertemporal elasticity of substitution are the same, which means that investors have homogeneous attitudes toward the risk across the states of nature and the risk over time in Iran but different ones in their values. Therefore, the assumption that the relative risk aversion is equal to the reciprocal of the elasticity of substitution is not valid in Iran's stock market.

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نویسندگان: 

Kazemi Ramin | Behtoei Ali | Kohansal Akram

اطلاعات دوره: 
  • سال: 

    2020
  • دوره: 

    5
  • شماره: 

    2
  • صفحات: 

    103-111
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    38
  • دانلود: 

    0
چکیده: 

‎Bucket recursive trees are an interesting and natural generalization of recursive trees‎. ‎In this model the nodes are buckets that can hold up to b≥ 1 labels‎. ‎The (modified) Zagreb index of a graph is defined as the sum of‎ ‎the squares of the outdegrees of all vertices in the graph‎. ‎We give the mean and variance of this index in random bucket recursive trees‎. ‎Also‎, ‎two limiting results on this index are given‎.

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بازدید 38

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نویسندگان: 

BLACK B.

نشریه: 

LARYNGOSCOPE

اطلاعات دوره: 
  • سال: 

    1995
  • دوره: 

    105
  • شماره: 

    (12 PT 2 SUPPL 76)
  • صفحات: 

    1-30
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    100
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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

بازدید 100

مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resourcesدانلود 0 مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resourcesاستناد 1 مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resourcesمرجع 0
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