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Showing 2 results for tahvilian
Volume 18, Issue 113 (july 2021)
Abstract
The drying process plays an important role in the treatment of medicinal plants, in order to maintain the quantity and quality of the essential oil extracted from the plant. Because Medicinal herbs containing essential oils If they are not dried immediately or their essence is not extracted, they will lose their active ingredients and volatile compounds.The aim of this study is design a hybrid dryer to drying medicinal plants and comparison their results with traditional drying methods (sun and shade).The effects of different drying methods (hybrid dryer, oven and shade drying) on the essential oil content and chemical composition of thyme were studied. The essential oils from each organ type were extracted by hydrodistillation and the chemical components were analyzed by GC/MS systems. Mathematical modeling results showed that the Midilli model can fit the drying curves with high accuracy. The highest essential oils yield of 2.4 % (v/w) was obtained by a hybrid dryer. Results indicated that hybrid dryer could keep the 24 Kinds of volatile compounds of Thymus while these values were 10 and 6 for oven and shadow methods, respectively. The main components of the essential oils in different drying methods were including alpha and beta pinene, caryophyllene, caryophyllene oxide, carotol, thymol, thymol methyl ether, terpinene-4-ol, gama-terpinene, p-cymene.In general, hybrid drying method is recommended as the best method for post-harvest thyme processing.
Volume 22, Issue 9 (September 2022)
Abstract
Low-cost and highly effective noise reduction has recently become one of the substantial challenges for industrial manufacturers. This paper presents the design and construction of a cost-effective system for attenuating single-frequency annoying noise generated from industrial products and machines. To achieve this goal, narrowband active noise control using Filtered-x Least Mean Square (FxLMS) method has been used with the help of a two-factor digital adaptive filter, called the adaptive notch filter. Therefore, a duct structure has been designed and experimental tests have been performed on it. To reduce implementation costs, the Arduino Uno board, which has an AVR microcontroller (ATmega328P), has been used as the controller. About 15dB noise attenuation at 400Hz and 750Hz frequencies and about 30dB noise attenuation at 650Hz and 950Hz frequencies have been achieved. Then, active noise control for two separate and simultaneous frequencies has been performed, which had somewhat effective results, and in one of these frequencies, noise attenuation of about 18dB has been observed.
