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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Journal of Particle Science & Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Mathematical modelling,Shrinkage,Drying rate,Vibro-Fluidized Bed Dryer,Hawthorn Drying
- چکیده:
- چکیده انگلیسی: The drying kinetics of hawthorn in a pilot-scale experimental fluidized bed dryer with and without vibration was investigated. The effect of operating parameters, such as vibration intensity, drying air flow rate, and temperature, on the drying rate and shrinkage of hawthorn was studied. The hawthorn fruit was dried at various drying air temperatures ranging from 40-70oC and drying air volume flow rates ranging from 22-30 m3/h with the vibration intensity ranging from 6.8 to 8.2 Hz. The entire drying process occurred in the falling rate period and no constant rate period was observed in the drying of hawthorn. Four mathematical drying models investigating the drying behavior of hawthorn were evaluated and then the experimental moisture data were fitted in these models. The quality of the models fitting was assessed using the coefficient of determination, chi-square and root mean square error. The logarithmic and Page models for drying rate and the Ratti and Vazquez models for shrinkage were found to be the most suitable for describing the drying and shrinkage curves of hawthorn. The results showed that the vibration intensity, drying air temperature and flow rate has no significant effect on the shrinkage of hawthorn. All mentioned parameters had a significant effect on the drying rate of hawthorn, but the effect of drying air temperature was considerably more compared to the other parameters. It was observed that shrinkage varies linearly with respect to moisture content, and the reduction in radial dimension of hawthorn samples was around 40% at the end of the drying process.
- انتشار مقاله: 27-10-1395
- نویسندگان: Elham Farzan,Mahmood Reza Rahimi,Vahid Madadi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Physics
- نوع مقاله: Journal Article
- کلمات کلیدی: Evaluation,Recovery,Enhancement ,Pre-Processing,Speckle
- چکیده:
- چکیده انگلیسی: Introduction
One of the most important pre-processing steps in optical coherence tomography (OCT) is reducing speckle noise, resulting from multiple scattering of tissues, which degrades the quality of OCT images.
Materials and Methods
The present study focused on speckle noise reduction and edge detection techniques. Statistical filters with different masks and noise variances were applied on OCT and test images. Objective evaluation of both types of images was performed, using various image metrics such as peak signal-to-noise ratio (PSNR), root mean square error, correlation coefficient and elapsed time. For the purpose of recovery, Kuan filter was used as an input for edge enhancement. Also, a spatial filter was applied to improve image quality.
Results
The obtained results were presented as statistical tables and images. Based on statistical measures and visual quality of OCT images, Enhanced Lee filter (3×3) with a PSNR value of 43.6735 in low noise variance and Kuan filter (3×3) with a PSNR value of 37.2850 in high noise variance showed superior performance over other filters.
Conclusion
Based on the obtained results, by using speckle reduction filters such as Enhanced Lee and Kuan filters on OCT images, the number of compounded images, required to achieve a given image quality, could be reduced. Moreover, use of Kuan filters for promoting the edges allowed smoothing of speckle regions, while preserving image tissue texture.- انتشار مقاله: 06-12-1393
- نویسندگان: Fereydoon Nowshiravan Rahatabad,Elham Farzaneh Bahalgerdy
- مشاهده