Thermal inactivation curves for peroxidase in potato extracts were determined in the range of 100 to 140°C for 10 to 100 sec. The capillary tube method was used to obtain isothermal conditions. The come-up time for the capillary tubes was accurately calculated by analysis method by which thermal inactivation kinetics of enzymes in relation to high temperature processing would be more easily detected. Heat inactivation of potato peroxidase followed first-order reaction kinetics and yielded a curved Arrhenius plot for the temperature dependence at high temperatures. Kinetics parameters, k and Ea, were calculated for potato peroxidase. At temperature range of 100-140°C, the activation energy of peroxidase was lower than that in the range of 78-84°C. It could be elucidated by the scheme of thermal inactivation pathway.

The modification of commercial ultra-stable Y zeolites using citric acid and phosphoric acid was investigated systematically via a L 18 (3 8) orthogonal experiment. The pore structure, acid property and crystal structural of modified USY zeolites were characterized by a variety of means such as N 2 adsorption-desorption, Fourier transform infrared spectroscopy, NH 3-temperature programmed desorption and X-ray diffraction. The optimal modification condition is found to be that the volume ratio of citric acid (0.3 mol/L) and phosphoric acid (0.3 mol/L) is 1.0, and the operation is performed at 100°C for 6 h. The as-synthesized sample presents an increased secondary pore volume up to 0.207 cm 3 /g which accounts for 42.9 % of the total pore volume, and appropriate acidity distribution as well as good crystallinity. In addition, the USY obtained by 1.0 L scale-up modification possesses a secondary pore volume of 0.210 cm 3 /g which accounts for 42.4 % of the total pore volume, showing no obvious scale-up effects. Furthermore, the hydrothermal stability of the modified samples meets the requirements of commercial catalysts for hydrocracking. Performance evaluation was carried out on a 200 mL fixedbed single stage hydrogenation unit using Daqing VGO as feedstock. The 140-370°C middle distillate yield is 66.09 %, and middle distillate selectivity can reach up to 80.45 %. Compared with commercial catalyst, the yield and selectivity are increased by 5.67 and 4.07 %, respectively.

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The modification of commercial ultra-stable Y (USY) zeolite using citric acid (CA) and ammonium fluosilicate (AFS) was investigated. A series of factors including the concentration of CA and AFS, the volume ratio of CA and AFS, adding rate of AFS, reaction time and temperature were studied to get the optimum operation condition. The pore structure, acid property and crystal structural of modified USY zeolite were characterized by a variety of means such as N 2 adsorption, Fourier transform infrared spectroscopy, NH 3 -temperature programmed desorption and X-ray diffraction. The as-synthesized sample presents an increased secondary pore volume up to 0.20 cm 3 /g which accounts for 46.5 % of the total pore volume, and appropriate acidity distribution as well as good crystallinity. In addition, the modified USY zeolite possesses a superhigh Si/Al ratio of 25.7 which is more than twice higher than that of commercial USY zeolite. Furthermore, the hydrothermal stability of the modified samples meet the requirements of commercial catalysts for hydrocracking. Performance evaluation was carried out on a 200 mL fixed-bed single stage hydrogenation unit using Daqing VGO as feedstock. The 140-370°C middle distillate yield is 67.78 %, and middle distillate selectivity can reach up to 80.76 %. Compared with commercial catalyst, the yield and selectivity are increased by 7.36 and 4.38 %, respectively.

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Intentional spoofing interference can cause damage to the navigation terminal and threaten the security of a global navigation satellite system (GNSS). For spoofing interference, an anti-spoofing algorithm based on pseudorange differences for a single receiver is proposed, which can be used to detect simplistic and intermediate spoofing attacks, as well as meaconing attacks. Double-difference models using the pseudorange of two adjacent epochs are established followed by the application of Taylor expansion to the position relationship between the satellite and the receiver (or the spoofer). The authenticity of the signal can be verified by comparing the results of the proposed spoofing detection algorithm with the traditional least squares method. The results will differ when spoofing is present. The parameter setting of the proposed algorithm is introduced. The algorithm has the advantage of both simplicity and efficiency and needs only a single receiver and pseudorange data. A NovAtel receiver is adopted for the actual experiments. The Texas spoofing test battery (TEXBAT), as well as two other simulation experiments are used to verify the performance of the algorithm. The simulation results validate the feasibility and effectiveness of the algorithm.

A high-frequency ultrasonic approach for testing and evaluating sprayed coating thickness is proposed in this paper. This technique is based on the maximum frequency interval method of the magnitude spectrum of the acoustic pressure reflection coefficient that adopts Welch spectrum estimation. The acoustic propagation model was set up at normal incidence, and the relationship between the maximum frequency interval by the Welch power spectrum and the coating thickness was established to provide the principle for determining coating thickness. According to this principle, the thickness of a series of stainless steel coatings and ZrO2–Y2O3 (yttria-stabilized zirconia (YSZ)) coatings were detected by scanning acoustic microscopy. The relative error was less than 4% with the microscope method, indicating that the proposed ultrasonic method provides a reliable nondestructive way to measure sprayed coating thickness. The uniformity of the sprayed coating thickness could be intuitively observed from C-scan images by programming.