Aim To design and experimentally study an 80C196KC-based SRD (switched re- luctance motor drive drive sytem) controller,Methods with the guidelines of the digitized SRD system controller,the circuit design and softwar...Aim To design and experimentally study an 80C196KC-based SRD (switched re- luctance motor drive drive sytem) controller,Methods with the guidelines of the digitized SRD system controller,the circuit design and software programming were completed,and a relevantexperimental system was PUT forward to test the newly designed controller.Result The experi-mental study showed that the newlydesigned controller had good speed-adjusting characteristicfor a switched reluctance motor ,its stable error was less than 5% and its full-load startingtime was shorter than 1.8s .Conclusion The new controller has reasonable circuit design and suitable controlling algorithm,and it is a feasible SRD system controller design scheme.展开更多
A new kinetic spectrophotometric method has been developed for the determination of trace Ni （Ⅱ in natural water. The method is based on the catalytic effect of Ni （Ⅱ） on the oxidation of weak acid brilliant blue...A new kinetic spectrophotometric method has been developed for the determination of trace Ni （Ⅱ in natural water. The method is based on the catalytic effect of Ni （Ⅱ） on the oxidation of weak acid brilliant blue dye （RAWL） by KIO4 in acid medium. The concentration of nickel （Ⅱ） can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ = 626 nm using the fix-time method. The influencing factors are investigated by the orthogonal experimental design. The obtained optimum analytical conditions are： pH = 2.00, CRAWL = 5.00×10^-5 mol·L^-1, c KlO4 = 2.00× 10^-5 mol·L^-1, the reaction time t= 10min and the temperature T = 25 ℃. Under the optimum conditions, the developed method allows the measurement of Ni （Ⅱ） in a range of 0 - 40.0ngmL1. The standard deviation of eleven independent measurements of blank reaction is S = 3.08× 10^-3 and the limit of detection is 2.20ng·mL^-1. The relative standard deviations （RSDs） in six replicate determinations of 5 ngmL-1 and 8 ngmL1 Ni （Ⅱ） are 2.87% and 1.11%, respectively. Moreover, the experiments show few cations and anions can interfere with the measurement of Ni （Ⅱ）. The recovery efficiencies of this method are in a range of 97.0%-102.5% in freshwater samples. But there is a decreasing effect, which is about 0.2 times the added Ni （Ⅱ） in seawater medium. After reasonable calibration this processing method is used for the determination of Ni （Ⅱ） in seawater samples successfully. The results show this developed method has high accuracy and precision, high sensitivity, large range of linearity and high speed. The method can, therefore, be employed at room temperature.展开更多
Due to the scarcity of fossil fuels in the world, there is increasing interest in the commercial production of biodiesel, which leads to obtaining large amounts of glycerol as a byproduct. If not disposed of properly,...Due to the scarcity of fossil fuels in the world, there is increasing interest in the commercial production of biodiesel, which leads to obtaining large amounts of glycerol as a byproduct. If not disposed of properly, glycerol can generate environmental impact. One of the promises, the application of the crude glycerol is the production of citric acid by microbial fermentation. Citric acid is industrially produced by a submerged fermentation process with Aspergillus niger, using sucrose as carbon source, but due to increased demand for citric acid, alternative processes using renewable sources or waste materials as substrates and the cultivation of yeast strains are being studied. The aim of the study was to determine the best culture condition for maximum citric acid synthesis and lower isocitric acid production from crude glycerol through experimental design tool. For this purpose, the yeast strain Yarrowia lipolytica IMUFRJ-50682 was cultivated in nitrogen-limited glycerol-based media. Therefore, glycerol and yeast extract concentrations and agitation speed were evaluated as independent variables. With pure glycerol, the highest citric acid production achieved was 16.5 g/L with an isocitric acid production of 7.7% （in relation to citric acid）. With crude glycerol, citric acid production reduced to 6.7 g/L because of higher biomass yield. Therefore, an increase in the initial carbon to nitrogen molar ratio from 714 to 1,561 was necessary to increase citric acid production to 9.2 g/L, reducing isocitric acid production and to achieve a yield of 0.41 g of citric acid per glycerol consumed. In this condition, less nitrogen source was used, reducing production costs.展开更多
文摘Aim To design and experimentally study an 80C196KC-based SRD (switched re- luctance motor drive drive sytem) controller,Methods with the guidelines of the digitized SRD system controller,the circuit design and software programming were completed,and a relevantexperimental system was PUT forward to test the newly designed controller.Result The experi-mental study showed that the newlydesigned controller had good speed-adjusting characteristicfor a switched reluctance motor ,its stable error was less than 5% and its full-load startingtime was shorter than 1.8s .Conclusion The new controller has reasonable circuit design and suitable controlling algorithm,and it is a feasible SRD system controller design scheme.
文摘A new kinetic spectrophotometric method has been developed for the determination of trace Ni （Ⅱ in natural water. The method is based on the catalytic effect of Ni （Ⅱ） on the oxidation of weak acid brilliant blue dye （RAWL） by KIO4 in acid medium. The concentration of nickel （Ⅱ） can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ = 626 nm using the fix-time method. The influencing factors are investigated by the orthogonal experimental design. The obtained optimum analytical conditions are： pH = 2.00, CRAWL = 5.00×10^-5 mol·L^-1, c KlO4 = 2.00× 10^-5 mol·L^-1, the reaction time t= 10min and the temperature T = 25 ℃. Under the optimum conditions, the developed method allows the measurement of Ni （Ⅱ） in a range of 0 - 40.0ngmL1. The standard deviation of eleven independent measurements of blank reaction is S = 3.08× 10^-3 and the limit of detection is 2.20ng·mL^-1. The relative standard deviations （RSDs） in six replicate determinations of 5 ngmL-1 and 8 ngmL1 Ni （Ⅱ） are 2.87% and 1.11%, respectively. Moreover, the experiments show few cations and anions can interfere with the measurement of Ni （Ⅱ）. The recovery efficiencies of this method are in a range of 97.0%-102.5% in freshwater samples. But there is a decreasing effect, which is about 0.2 times the added Ni （Ⅱ） in seawater medium. After reasonable calibration this processing method is used for the determination of Ni （Ⅱ） in seawater samples successfully. The results show this developed method has high accuracy and precision, high sensitivity, large range of linearity and high speed. The method can, therefore, be employed at room temperature.
文摘Due to the scarcity of fossil fuels in the world, there is increasing interest in the commercial production of biodiesel, which leads to obtaining large amounts of glycerol as a byproduct. If not disposed of properly, glycerol can generate environmental impact. One of the promises, the application of the crude glycerol is the production of citric acid by microbial fermentation. Citric acid is industrially produced by a submerged fermentation process with Aspergillus niger, using sucrose as carbon source, but due to increased demand for citric acid, alternative processes using renewable sources or waste materials as substrates and the cultivation of yeast strains are being studied. The aim of the study was to determine the best culture condition for maximum citric acid synthesis and lower isocitric acid production from crude glycerol through experimental design tool. For this purpose, the yeast strain Yarrowia lipolytica IMUFRJ-50682 was cultivated in nitrogen-limited glycerol-based media. Therefore, glycerol and yeast extract concentrations and agitation speed were evaluated as independent variables. With pure glycerol, the highest citric acid production achieved was 16.5 g/L with an isocitric acid production of 7.7% （in relation to citric acid）. With crude glycerol, citric acid production reduced to 6.7 g/L because of higher biomass yield. Therefore, an increase in the initial carbon to nitrogen molar ratio from 714 to 1,561 was necessary to increase citric acid production to 9.2 g/L, reducing isocitric acid production and to achieve a yield of 0.41 g of citric acid per glycerol consumed. In this condition, less nitrogen source was used, reducing production costs.
