---

Because of high accuracy and low weight-to-force ratio, servo hydraulic systems are widely used in various branches of industry. Simultaneous improvement of accuracy and time response are among ever increasing needs for these systems. Rapid movement commands to hydraulic actuator excite attached mechanical components and consequently produce undesired vibrations. Recommended solution to overcome the above mentioned problem is to design and implement advanced controller which takes into consideration the high frequency uncertainties. In this research a two-degree-of–freedom (2DOF) position controller has been design and implemented for undesirable vibration regulation and robust performance achievement on a servo hydraulic table. In this regard various elements of the system are modeled and then the servo hydraulic table nominal system and uncertainty are identified using grey-box method. The 2DOF robust controller is designed using general H∞ framework and analyzed by structured singular value, Mu. The feedback block of controller is used to reduce the effect of uncertainty, measurement noises and reject disturbances, whereas the forward controller shapes the command signals to improve the performance. The designed controller has been implemented on the servo hydraulic test rig in order to track sine and trapezoid position command signals. It has been observed the controller has a more accurate performance and faster time response than the common robust controller with just one feedback block. Extensive experimental results of the developed controller indicate robust performance and acceptable response to disturbance and measurement noise rejection in the defined uncertainty range.

---

In this study, the effect of three amplitudes of Ultrasound-Assisted Solvent Extraction (UASE) (0, 20 and 40%; 100W, 30 kHz; the 0% treatment serving as control) on kinetics, thermodynamic, rosmarinic acid content, total phenolics, antioxidant activity, and antimicrobial activity of Ocimum basilicum L. (basil) extract at different temperatures (25, 35 and 45°C) was evaluated. Increases in ultrasound amplitude and temperature increased yields and biological activities of extracts. The highest rosmarinic acid content, total phenolics, antioxidant and antimicrobial activity were obtained for samples treated with UASE at 40% amplitude and 45°C. The kinetics of extraction were evaluated based on a second order mechanism. Increases of amplitude and temperature significantly increased saturated extraction Capacity (C_s), initial extraction rate (h), and rate constant of extraction (k). The thermodynamic aspects of the extraction process showed that samples treated with UASE at 40% amplitude had higher activation Energy (Ea), frequency factor (A), enthalpy (ΔH⁺⁺) and entropy (ΔS⁺⁺) than control. UASE at 40% amplitude and control did not significantly differ in thermodynamic parameters. Results also showed very good linear relationships with high correlation coefficients between E_a and ΔH⁺⁺ and, A and ΔS⁺⁺. Therefore, ultrasound can affect thermodynamic aspects and kinetics of extraction of basil extract and improve its biological activity.

---

One of the important innovations in sericulture is utilizing the hybrid silkworm eggs, which, with a clearer view about it, may assist extensional experts in the development of sericulture. This study aimed to explore the agriculturists’ knowledge of and attitude on the silkworm eggs distributed in Guilan Province. This is a quantitative, applied and descriptive-survey research. Due to the expansion of sericulture in Guilan Province, Langaroud and Shaft cities, which had the highest number of sericulturists, were chosen to do the multistage sampling. Then, through simple random sampling, 168 cases from Langaroud and 184 cases from Shaft were selected. Researcher-made questionnaires were filled in five categories (individual-professional characteristics, knowledge, and attitude, satisfaction, and factors contributing to satisfaction). Face and content validity was confirmed through consultations with 10 professors as well as with sericulture specialists and reliability was confirmed using Cronbach’s Alpha. Studies showed no significant difference in seri culturists’ knowledge and performance with regard to different types of distributed eggs. This indicated that seri culturists’ location had no impact on their attitude on the usage of the distributed eggs. However, the type of silkworm egg used affected the farmers’ attitude, resulting in a statistically significant difference. The majority of sericulturists were moderately satisfied with sericulture practices in Guilan Province. Furthermore, individual characteristics as well as access to facilities and financial and moral support most significantly affected their satisfaction. Despite the unique features of each egg type, sericulturists’ similar attitude of hybrid types indicated their poor and limited knowledge of raising the eggs.