تأثیر کاهش نویز در تحلیل‌ آشوبی جریان رودخانه‌‌ نازلوچای

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشیار گروه مهندسی آب، دانشکده کشاورزی دانشگاه ارومیه

2 دانش‌آموخته کارشناسی ارشد مهندسی منابع آب، دانشکده کشاورزی دانشگاه ارومیه

چکیده

با توجه به ماهیت دینامیک و غیر خطی جریان رودخانه، می‌توان انتظار داشت که سری زمانی جریان رودخانه از یک سیستم دینامیکی قطعی آشوبی به‌دست آمده باشد. با توجه به اینکه سری‌های زمانی به‌دست آمده از پدیده‌های طبیعی عموماً با نویز مخدوش شده‌اند، وجود نویز فرآیند تحلیل‌های آشوبی و در نهایت پیش‌بینی سری‌های زمانی را با محدودیت‌هایی مواجه می‌سازد. بنابراین در این تحقیق با استفاده از آمار دبی‌های روزانه‌ رودخانه نازلوچای در دوره مهر 1369 تا شهریور 1391، تحلیل‌ آشوبی شامل بررسی وجود آشوب با استفاده از روش بعد همبستگی و نیز شبیه‌سازی جریان رودخانه با استفاده از مدل تقریب موضعی انجام پذیرفت. سپس به‌منظور بررسی تأثیر نویز در فرآیند تحلیل‌ها، کاهش نویز سری زمانی به‌روش غیر خطی مبتنی بر بازسازی فضای حالت انجام گرفت. نتایج نشان‌دهنده‌ کاهش 07/6 درصدی بعد همبستگی و افزایش دقت مدل تقریب موضعی برای سری نویز زدایی شده نسبت به سری اصلی داده‌ها (افزایش09/1 درصدی R2 و کاهش 48 درصدی RMSE) بود. در نهایت با استفاده از مدل منتخب شبیه‌سازی، پیش‌بینی جریان رودخانه با استفاده از سری اصلی و سری نویز زدایی شده برای  سال آبی 92-91 انجام گرفت. نتایج مدل پیش‌بینی با استفاده از سری نویززدایی شده دارای دقت بیشتری نسبت به مدل با استفاده از سری اصلی بود.

کلیدواژه‌ها


عنوان مقاله [English]

Noise Reduction Effect on Chaotic Analysis of Nazluchay River Flow

نویسندگان [English]

  • H Rezaei 1
  • S Jabbari Gharabagh 2
1 Assoc. Prof., Water Eng. Dep., Faculty of agriculture, Urmia University, Iran
2 Former M.Sc. Student, Water Eng. Dep., Faculty of agriculture, Urmia University, Iran
چکیده [English]

Considering the dynamic and nonlinear nature of river flow, it is expected that the river flow time series is obtained from a deterministic chaotic system. Since that the time series obtained from the natural phenomena are generally contaminated by noise, the presence of noise limits the chaotic analysis and consequently makes limitations in the prediction of time series. For this reason, in this study the chaotic analysis, including the evaluation of the presence of chaos using correlation dimension and simulating the river flow using Local Approximation Method, was investigated on daily series of Nazluchay River during the 1990 to 2012 period. Afterwards, in order to evaluate the noise effect on the process of analysis, noise reduction of time series was carried out by a nonlinear method based on phase space reconstruction. The results showed 6.07% decrease in correlation dimension and an increase in model accuracy for the noise reduced time series with respect to the original series (1.09% increase in R2 and 48% decrease in RMSE). Finally, by the selected simulation model, prediction of the river flow was done using the original and noise reduced time series for the 2012-2013 period. The model results predicted with the noise reduced series were found to be more accurate than those with the original series.

کلیدواژه‌ها [English]

  • Correlation dimension
  • Local approximation model
  • Noise reduction
  • Phase space reconstruction
  • Prediction
 
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