B. Shanshiashvili1, N. Kavlashvili2
1. Department of Control Systems, Georgian Technical University, Kostava Str, 0160, Tbilisi, Georgia.
2. Archil Eliashvili Institute of Control Systems of Georgian Technical University, Mindeli Str., 0186, Tbilisi, Georgia.
Abstract: the problem of parameter identification of nonlinear dynamic systems of industrial processes on the set of continuous block-oriented models, the elements of which are different modifications of the Hammerstein and Wiener models, is considered. Method of parameter identification in steady state based on the observation of the system’s input and output variables at the input sinusoidal influences is proposed. The solution of the problem of parameter identification is reduced to the solution of the systems of algebraic equations by using the Fourier approximation. The parameters estimations are received by the least squares method. Reliability of the received results, at the parameter identification of the nonlinear system in industrial conditions at the presence of noise, depends on the accuracy of the measurement of system output signals and mathematical processing of the experimental data at the approximation.
Keywords: nonlinear system, block-oriented model, control, identification, parameter, sinusoidal.
Pages: 21 – 34 | Full PDF Paper
Safe Concentration of Silver Nanoparticles in Solution for White Leg Shrimp (Litopeaneus vannamei) Farming
Phuong Hong Lam1, Mai Thi Le1, Dung My Thi Dang1, Tin Chanh Duc Doan1, Nguyen Phuc Cam Tu2, Chien Mau Dang1
1. Institute for Nanotechnology (INT), Vietnam National University – Ho Chi Minh City (VNUHCM), Vietnam.
2. Faculty of Fisheries, Nong Lam University – Ho Chi Minh City, Vietnam.
Abstract: There have been many bactericidal chemicals used to limit the growth of bacteria in white leg shrimp culture. Silver nanoparticles have been used in filtering devices or mixed with the commercial feed to decrease the bacteria and fungus in shrimp farming. Adding silver nanoparticles directly to the culturing water has not been reported due to worries about bioaccumulation, polluted environment and their effect on the aquatic animals. However, studies on the effects of silver nanoparticles on cultured species have hardly been conducted. In this paper, we report the determination of the safe concentration of the silver nanoparticles for white leg shrimp by determining the acute toxicity of the used silver nanoparticles (LC50-48h and LC50-24h) for adult white leg shrimps (35 days old). The results showed that white leg shrimps exposed to the silver nanoparticles for 48 hours with concentrations greater than 100 ppm had high mortality (> 90%). The LC50-24h and LC50-48h values of the silver nanoparticles for Litopeaneus vannamei were determined to be 91.2 ppm and 35.5 ppm, respectively. The safety level of the silver nanoparticles recommended to be used for the white leg shrimp culture was 1.61 ppm.
Keywords: silver nanoparticles, growth rate, Penaeus vannamei, survival rate, Vibrio spp.
Pages: 35 – 45 | Full PDF Paper