The highly pure nano-crystal Mg,Al-hydrotalcite with titania doping was synthesized by one-step liquid reaction method at atmospheric pressure. The preparation of the Mg,Al-hydrotalcite nano-crystal after doping titan...The highly pure nano-crystal Mg,Al-hydrotalcite with titania doping was synthesized by one-step liquid reaction method at atmospheric pressure. The preparation of the Mg,Al-hydrotalcite nano-crystal after doping titania was investigated according to the results of XRD, TEM, IR and DSC. Moreover, based on the DSC test results, the thermal mechanism functions of the Mg,Al-hydrotalcite with titania doping were studied after calculation and comparison.展开更多
SrTiO_3 nano-crystal samples with floccule or flake crystal morphology,which were indexed as a perovskite-type crystal structure based on the results of XRD and TEM,were successfully prepared by one-step liquid reacti...SrTiO_3 nano-crystal samples with floccule or flake crystal morphology,which were indexed as a perovskite-type crystal structure based on the results of XRD and TEM,were successfully prepared by one-step liquid reaction method.And the growth mechanism of the SrTiO_3 nano-crystals under the liquid condition with/without adding the surface active agent was investigated.It was found that adding the surface active agent contributes to the processing in which the ions gathering bodies transit to a more stable phase through the chemical reaction and form the flake SrTiO_3 nano-crystals.展开更多
The idea of fractional dimension was stated in brief firstly.Then,adopting the fractional statistical similar principle, the method of the least square minimum error was applied to evaluate the fractional dimension of...The idea of fractional dimension was stated in brief firstly.Then,adopting the fractional statistical similar principle, the method of the least square minimum error was applied to evaluate the fractional dimension of per image pixel depending on the fractional property of image.And the image edge is extracted by magnitude of fractional dimension of image pixel.We presented the algorithm of the local fractional dimension,which made the rule of window size and sentencing the fractional dimension of edge.Although this algorithm was waste time,it is better than the classical ones in extraction edge and anti-jamming.展开更多
Needs in scintimammography applications,especially for small animal cardiac imaging,lead to develop a small field of view,high spatial resolution gamma camera with a pinhole collimator.However the ideal pinhole collim...Needs in scintimammography applications,especially for small animal cardiac imaging,lead to develop a small field of view,high spatial resolution gamma camera with a pinhole collimator.However the ideal pinhole collimator must keep a compromise between spatial resolution and sensitivity.In order to design a pinhole collimator with an optimized sensitivity and spatial resolution,the spatial resolution and the geometric sensitivity response as a function of the source to collimator distance has been obtained by means of Monte-Carlo simulation for a small field of view gamma camera with a pinhole collimator of various-hole diameters.The results show that the camera with pinhole of 1 mm,1.5 mm and 2 mm diameter has respectively spatial resolution of 1.5 mm,2.25 mm and 3 mm and geometric sensitivity of 0.016%,0.022%and 0.036%,while the source to collimator distance is 3 cm.We chose the pinhole collimator with hole diameter size of 1.2 mm for our the gamma camera designed based on the trade-off between sensitivity and resolution.展开更多
The strap-down inertial navigation system (SINS) error of ballistic missile is generated by the mutual influence of gyroscope and accelerometer, and the recursive model is completely different from that of gimbaled IN...The strap-down inertial navigation system (SINS) error of ballistic missile is generated by the mutual influence of gyroscope and accelerometer, and the recursive model is completely different from that of gimbaled INS. In the paper, a discrete error recursive model was obtained by studying the applied SINS error model of ballistic missile, and the discrete Kalman filtering simulation based on the model was carried out. The simulated results show that the model can depict the SINS error exactly and provide the advantages for research on integrated guidance and improved hit accuracy.展开更多
Aiming at that the successive test data set of the strapdown inertial measurement unit is always small,a Bayesian method is used to study its statistical characteristics.Its prior and posterior distributions are set u...Aiming at that the successive test data set of the strapdown inertial measurement unit is always small,a Bayesian method is used to study its statistical characteristics.Its prior and posterior distributions are set up by the method and the pretest,sample and population information.Some statistical inferences can be made based on the posterior distribution.It can reduce the statistical analysis error in the case of small sample set.展开更多
The fatigue crack propagation behavior of the LY12CZ aluminum alloy fastener involving a central hole in air or in 3.5wt% NaCl solution was investigated. The experimental results indicated that the corrosion fatigue c...The fatigue crack propagation behavior of the LY12CZ aluminum alloy fastener involving a central hole in air or in 3.5wt% NaCl solution was investigated. The experimental results indicated that the corrosion fatigue crack growth rate decreased with the increasing loading frequency,and in a corrosive environment,the crack growth rate was slightly larger than that in air. Based on the experimental results,the virtual corrosion fatigue crack propagation tests were investigated and the stochastic process method and the AFGROW simulation method were presented. The normal process and lognormal process were considered for the stochastic process method based on the numerically fitted Paris equation. The distribution of crack size and the corresponding probabilistic model of crack length distribution for a given number of cycles can be found by integrating the stochastic process over time. Using the AFGROW software,the virtual simulation was carried out to analyze the corrosion fatigue crack growth behavior and the predicted crack growth curve was in good agreement with the experimental results.展开更多
On the basis of good anticorrosion capability of silicate glass,silicate glass coating was sprayed by high velocity oxygen fuel (HVOF) and the corrosion mechanism in 5% NaCl solution was studied. Scanning electron mic...On the basis of good anticorrosion capability of silicate glass,silicate glass coating was sprayed by high velocity oxygen fuel (HVOF) and the corrosion mechanism in 5% NaCl solution was studied. Scanning electron microscope (SEM) ,energy dispersive X-ray analysis (EDX) ,X-ray diffraction (XRD) and potentiom- eter were used to study the coating composition and corrosion process. The result shows that silicate glass coating is entirely noncrystallizable. Silicate glass coating has very low incidence of hole with compact structure. Electric double-layer can form at coating/solution interface and corrosive solution performs as a lead connecting the coating surface and substrate after permeating through glass coating. The corrosion mechanism of silicate glass coating is similar to that of glass and the entire corrosion process can be divided into some states. The whole corrosion process happens in glass coating without substrate basically. The fluctuation of the self-corrosion potential about glass coating in corrosion solution can help to research the corrosion process.展开更多
Through theoretical analysis of reliability and simulation analysis of dispersivi of d a/ d N based on Monte Carlo method, the distribution function of n and c was set up. Meanwhile, the distribution of critical ...Through theoretical analysis of reliability and simulation analysis of dispersivi of d a/ d N based on Monte Carlo method, the distribution function of n and c was set up. Meanwhile, the distribution of critical opening displacement(COD)δ c was defined by the use of coherent coefficient method, and the probabilistic model of defects assessment of military special vessel was built. Thereby the theoretical and practical fundamental research on evaluation of reliability of military high pressure vessels was carried out.展开更多
To improve the precision of the filling pressure curve of differential pressure casting controlled with PID controller,the model of differential pressure casting process is established and two pressure-difference cont...To improve the precision of the filling pressure curve of differential pressure casting controlled with PID controller,the model of differential pressure casting process is established and two pressure-difference control systems using PID algorithm and Dahlin algorithm are separately designed in MATLAB. The scheduled pressure curves controlled with PID algorithm and Dahlin algorithm,respectively,are comparatively simulated in MATLAB. The simulated pressure curves obtained show that the control precision with Dahlin algorithm is higher than that with PID algorithm in the differential pressure casting process,and it was further verified by production practice.展开更多
SVM handles classification problem only considering samples themselves and the classification effect depends on the characteristics of the training samples but not the current information of classified problem.From th...SVM handles classification problem only considering samples themselves and the classification effect depends on the characteristics of the training samples but not the current information of classified problem.From the phenomena of data crossing in systems,this paper improves the classification effect of SVM by adding the prior probability item reflecting the classified problem information into the decision function,which fuses the Bayesian criterion into SVM.The detailed deducing process and realizing steps of the algorithm are put forward.It is verified through two instances.The results showthat the new algorithm has better effect than the traditional SVM algorithm,and its robustness and sensitivity are all improved.展开更多
Large temperature drift is an important factor for improving the performance of FOG.A trend term of temperature drift of FOG is obtained using stationary wavelets transform,and an FOG drift algorithm with least square...Large temperature drift is an important factor for improving the performance of FOG.A trend term of temperature drift of FOG is obtained using stationary wavelets transform,and an FOG drift algorithm with least squares wavelet support vector machine(LS-WSVM) is developed.The algorithm used Maxihat wavelet as a kernel function of LS-WSVM to establish an FOG drift model.It has better modeling precise than LS-WSVM model with Gauss kernel.Results indicate the efficiency of this algorithm of LS-WSVM.展开更多
基金Project (2004E113) Supported by Natural Science Basic Research Plan of Shaanxi Province of China
文摘The highly pure nano-crystal Mg,Al-hydrotalcite with titania doping was synthesized by one-step liquid reaction method at atmospheric pressure. The preparation of the Mg,Al-hydrotalcite nano-crystal after doping titania was investigated according to the results of XRD, TEM, IR and DSC. Moreover, based on the DSC test results, the thermal mechanism functions of the Mg,Al-hydrotalcite with titania doping were studied after calculation and comparison.
文摘SrTiO_3 nano-crystal samples with floccule or flake crystal morphology,which were indexed as a perovskite-type crystal structure based on the results of XRD and TEM,were successfully prepared by one-step liquid reaction method.And the growth mechanism of the SrTiO_3 nano-crystals under the liquid condition with/without adding the surface active agent was investigated.It was found that adding the surface active agent contributes to the processing in which the ions gathering bodies transit to a more stable phase through the chemical reaction and form the flake SrTiO_3 nano-crystals.
文摘The idea of fractional dimension was stated in brief firstly.Then,adopting the fractional statistical similar principle, the method of the least square minimum error was applied to evaluate the fractional dimension of per image pixel depending on the fractional property of image.And the image edge is extracted by magnitude of fractional dimension of image pixel.We presented the algorithm of the local fractional dimension,which made the rule of window size and sentencing the fractional dimension of edge.Although this algorithm was waste time,it is better than the classical ones in extraction edge and anti-jamming.
基金Supported by National Foundation of Nature Science of China(No.10275063)
文摘Needs in scintimammography applications,especially for small animal cardiac imaging,lead to develop a small field of view,high spatial resolution gamma camera with a pinhole collimator.However the ideal pinhole collimator must keep a compromise between spatial resolution and sensitivity.In order to design a pinhole collimator with an optimized sensitivity and spatial resolution,the spatial resolution and the geometric sensitivity response as a function of the source to collimator distance has been obtained by means of Monte-Carlo simulation for a small field of view gamma camera with a pinhole collimator of various-hole diameters.The results show that the camera with pinhole of 1 mm,1.5 mm and 2 mm diameter has respectively spatial resolution of 1.5 mm,2.25 mm and 3 mm and geometric sensitivity of 0.016%,0.022%and 0.036%,while the source to collimator distance is 3 cm.We chose the pinhole collimator with hole diameter size of 1.2 mm for our the gamma camera designed based on the trade-off between sensitivity and resolution.
文摘The strap-down inertial navigation system (SINS) error of ballistic missile is generated by the mutual influence of gyroscope and accelerometer, and the recursive model is completely different from that of gimbaled INS. In the paper, a discrete error recursive model was obtained by studying the applied SINS error model of ballistic missile, and the discrete Kalman filtering simulation based on the model was carried out. The simulated results show that the model can depict the SINS error exactly and provide the advantages for research on integrated guidance and improved hit accuracy.
文摘Aiming at that the successive test data set of the strapdown inertial measurement unit is always small,a Bayesian method is used to study its statistical characteristics.Its prior and posterior distributions are set up by the method and the pretest,sample and population information.Some statistical inferences can be made based on the posterior distribution.It can reduce the statistical analysis error in the case of small sample set.
文摘The fatigue crack propagation behavior of the LY12CZ aluminum alloy fastener involving a central hole in air or in 3.5wt% NaCl solution was investigated. The experimental results indicated that the corrosion fatigue crack growth rate decreased with the increasing loading frequency,and in a corrosive environment,the crack growth rate was slightly larger than that in air. Based on the experimental results,the virtual corrosion fatigue crack propagation tests were investigated and the stochastic process method and the AFGROW simulation method were presented. The normal process and lognormal process were considered for the stochastic process method based on the numerically fitted Paris equation. The distribution of crack size and the corresponding probabilistic model of crack length distribution for a given number of cycles can be found by integrating the stochastic process over time. Using the AFGROW software,the virtual simulation was carried out to analyze the corrosion fatigue crack growth behavior and the predicted crack growth curve was in good agreement with the experimental results.
文摘On the basis of good anticorrosion capability of silicate glass,silicate glass coating was sprayed by high velocity oxygen fuel (HVOF) and the corrosion mechanism in 5% NaCl solution was studied. Scanning electron microscope (SEM) ,energy dispersive X-ray analysis (EDX) ,X-ray diffraction (XRD) and potentiom- eter were used to study the coating composition and corrosion process. The result shows that silicate glass coating is entirely noncrystallizable. Silicate glass coating has very low incidence of hole with compact structure. Electric double-layer can form at coating/solution interface and corrosive solution performs as a lead connecting the coating surface and substrate after permeating through glass coating. The corrosion mechanism of silicate glass coating is similar to that of glass and the entire corrosion process can be divided into some states. The whole corrosion process happens in glass coating without substrate basically. The fluctuation of the self-corrosion potential about glass coating in corrosion solution can help to research the corrosion process.
文摘Through theoretical analysis of reliability and simulation analysis of dispersivi of d a/ d N based on Monte Carlo method, the distribution function of n and c was set up. Meanwhile, the distribution of critical opening displacement(COD)δ c was defined by the use of coherent coefficient method, and the probabilistic model of defects assessment of military special vessel was built. Thereby the theoretical and practical fundamental research on evaluation of reliability of military high pressure vessels was carried out.
文摘To improve the precision of the filling pressure curve of differential pressure casting controlled with PID controller,the model of differential pressure casting process is established and two pressure-difference control systems using PID algorithm and Dahlin algorithm are separately designed in MATLAB. The scheduled pressure curves controlled with PID algorithm and Dahlin algorithm,respectively,are comparatively simulated in MATLAB. The simulated pressure curves obtained show that the control precision with Dahlin algorithm is higher than that with PID algorithm in the differential pressure casting process,and it was further verified by production practice.
文摘SVM handles classification problem only considering samples themselves and the classification effect depends on the characteristics of the training samples but not the current information of classified problem.From the phenomena of data crossing in systems,this paper improves the classification effect of SVM by adding the prior probability item reflecting the classified problem information into the decision function,which fuses the Bayesian criterion into SVM.The detailed deducing process and realizing steps of the algorithm are put forward.It is verified through two instances.The results showthat the new algorithm has better effect than the traditional SVM algorithm,and its robustness and sensitivity are all improved.
文摘Large temperature drift is an important factor for improving the performance of FOG.A trend term of temperature drift of FOG is obtained using stationary wavelets transform,and an FOG drift algorithm with least squares wavelet support vector machine(LS-WSVM) is developed.The algorithm used Maxihat wavelet as a kernel function of LS-WSVM to establish an FOG drift model.It has better modeling precise than LS-WSVM model with Gauss kernel.Results indicate the efficiency of this algorithm of LS-WSVM.
