A bandgap voltage reference is presented with a piecewise linear compensating circuit in order to reduce the temperature coefficient.The basic principle is to divide the whole operating temperature range into some su...A bandgap voltage reference is presented with a piecewise linear compensating circuit in order to reduce the temperature coefficient.The basic principle is to divide the whole operating temperature range into some sub ranges.At different temperature sub ranges the bandgap reference can be compensated by different linear functions.Since the temperature sub range is much narrower than the whole range,the compensation error can be reduced significantly.Theoretically,the precision can be improved unlimitedly if the sub ranges are narrow enough.In the given example,with only three temperature sub ranges,the temperature coefficient of a conventional bandgap reference drops from 1 5×10 -5 /℃ to 2×10 -6 /℃ over the -40℃ to 120℃ temperature range.展开更多
By summing geophone and hydrophone data with opposite polarity responses to water layer reverberation,the ocean bottom cable dual-sensor acquisition technique can effectively eliminate reverberation,broaden the freque...By summing geophone and hydrophone data with opposite polarity responses to water layer reverberation,the ocean bottom cable dual-sensor acquisition technique can effectively eliminate reverberation,broaden the frequency bandwidth,and improve both the resolution and fidelity of the seismic data.It is thus widely used in industry.However,it is difficult to ensure good coupling of the geophones with the seabed because of the impact of ocean flow,seafloor topography,and field operations;therefore,geophone data are seriously affected by the transfer function of the geophone-seabed coupling system.As a result,geophone data frequently have low signal-to-noise ratios（S/N）,which causes large differences in amplitude,frequency,and phases between geophone and hydrophone data that severely affect dual-sensor summation.In contrast,the hydrophone detects changes in brine pressure and has no coupling issues with the seabed;thus,hydrophone data always have good S/N.First,in this paper,the mathematical expression of the transfer function between geophone and seabed is presented.Second,the transfer function of the geophone-seabed is estimated using hydrophone data as reference traces,and finally,the coupling correction based on the estimated transfer function is implemented.Using this processing,the amplitude and phase differences between geophone and hydrophone data are removed,and the S/N of the geophone data are improved.Synthetic and real data examples then show that our method is feasible and practical.展开更多
A new approach for rules-based optical proximity correction is presented.The discussion addresses on how to select and construct more concise and practical rules-base as well as how to apply that rules-base.Based on t...A new approach for rules-based optical proximity correction is presented.The discussion addresses on how to select and construct more concise and practical rules-base as well as how to apply that rules-base.Based on those ideas,several primary rules are suggested.The v-support vector regression method is used to generate a mathematical expression according to rule data.It enables to make correction according to any given rules parameters.Experimental results demonstrate applying rules calculated from the expression match well with that from the rule table.展开更多
Stacking velocity V_（C2）,vertical velocity ratio γ_0,effective velocity ratio γ_（eff）,and anisotropic parameter x_（eff） are correlated in the PS-converted-wave（PS-wave） anisotropic prestack Kirchhoff time mi...Stacking velocity V_（C2）,vertical velocity ratio γ_0,effective velocity ratio γ_（eff）,and anisotropic parameter x_（eff） are correlated in the PS-converted-wave（PS-wave） anisotropic prestack Kirchhoff time migration（PKTM） velocity model and are thus difficult to independently determine.We extended the simplified two-parameter（stacking velocity V_（C2） and anisotropic parameter k_（eff）） moveout equation from stacking velocity analysis to PKTM velocity model updating and formed a new four-parameter（stacking velocity V_（C2）,vertical velocity ratio γ_0,effective velocity ratio γ_（eff）,and anisotropic parameter k_（eff）） PS-wave anisotropic PKTM velocity model updating and process flow based on the simplified twoparameter moveout equation.In the proposed method,first,the PS-wave two-parameter stacking velocity is analyzed to obtain the anisotropic PKTM initial velocity and anisotropic parameters;then,the velocity and anisotropic parameters are corrected by analyzing the residual moveout on common imaging point gathers after prestack time migration.The vertical velocity ratio γ_0 of the prestack time migration velocity model is obtained with an appropriate method utilizing the P- and PS-wave stacked sections after level calibration.The initial effective velocity ratio γ_（eff） is calculated using the Thomsen（1999） equation in combination with the P-wave velocity analysis;ultimately,the final velocity model of the effective velocity ratio γ_（eff） is obtained by percentage scanning migration.This method simplifies the PS-wave parameter estimation in high-quality imaging,reduces the uncertainty of multiparameter estimations,and obtains good imaging results in practice.展开更多
Data reconciliation is an effective technique for providing accurate and consistent value for chemical process. However, the presence of gross errors can severely bias the reconciled results. Robust estimators can sig...Data reconciliation is an effective technique for providing accurate and consistent value for chemical process. However, the presence of gross errors can severely bias the reconciled results. Robust estimators can significantly reduce the effect of gross errors and yield less-biased results. In this article, a new method is proposed to solve the robust data reconciliation problem of nonlinear chemical process. By using several technologies including linearization method, penalty function, virtual observation equation, and equivalent weights method, the robust data reconciliation problem can be transformed into least squares estimator problem which leads to the convenience in computation. Simulation results in a nonlinear chemical process demonstrate the efficiency of the proposed method.展开更多
In the past few years, network RTK positioning technology, especially the VRS technology, has been widely used in some parts of China and in many countries around the world. The principle of the VRS technology is disc...In the past few years, network RTK positioning technology, especially the VRS technology, has been widely used in some parts of China and in many countries around the world. The principle of the VRS technology is discussed with corresponding formula deduction, and detailed descriptions and applications of VRS corrections and virtual observations generation algorithm are given.展开更多
Outlier in one variable will smear the estimation of other measurements in data reconciliation （DR）. In this article, a novel robust method is proposed for nonlinear dynamic data reconciliation, to reduce the influe...Outlier in one variable will smear the estimation of other measurements in data reconciliation （DR）. In this article, a novel robust method is proposed for nonlinear dynamic data reconciliation, to reduce the influence of outliers on the result of DR. This method introduces a penalty function matrix in a conventional least-square objective function, to assign small weights for outliers and large weights for normal measurements. To avoid the loss of data information, element-wise Mahalanobis distance is proposed, as an improvement on vector-wise distance, to construct a penalty function matrix. The correlation of measurement error is also considered in this article. The method introduces the robust statistical theory into conventional least square estimator by constructing the penalty weight matrix and gets not only good robustness but also simple calculation. Simulation of a continuous stirred tank reactor, verifies the effectiveness of the proposed algorithm.展开更多
An NT-MT combined method based on nodal test (NT) and measurement test (MT) is developed for gross error detection and data reconciliation for industrial application. The NT-MT combined method makes use of both NT and...An NT-MT combined method based on nodal test (NT) and measurement test (MT) is developed for gross error detection and data reconciliation for industrial application. The NT-MT combined method makes use of both NT and MT tests and this combination helps to overcome the defects in the respective methods. It also avoids any artificial manipulation and eliminates the huge combinatorial problem that is created in the combined method based on the nodal test in the case of more than one gross error for a large process system. Serial compensation strategy is also used to avoid the decrease of the coefficient matrix rank during the computation of the proposed method. Simulation results show that the proposed method is very effective and possesses good performance.展开更多
Improving the accuracy and precision of coal bed methane(CBM) estimates requires correction of older data from older coal exploration surveys to newer standards.Three methods,the depth gradient method,the contour aeri...Improving the accuracy and precision of coal bed methane(CBM) estimates requires correction of older data from older coal exploration surveys to newer standards.Three methods,the depth gradient method,the contour aerial weight method,and the well-point aerial weight method,were used to estimate the correction coefficient required to predict CBM gas content from coal exploration data.The data from the Nos.3 and 15 coal seams provided the coal exploration data while the CBM exploration stages within the X1 well block located in the southern part of the Qinshui Basin provided the data obtained using newer standards.The results show the correction coefficients obtained from the two aerial weight methods are similar in value but lower than the one obtained from the depth gradient method.The three methods provide similar results for the Nos.3 and 15 seams in that the correction factor is lower for the former seam.The results from the depth gradient method taken together with the coal seam burial depth and the coal rank suggest that variations in the correction factor increase linearly along with coal seam burial depth and coal rank.The correlation obtained can be applied to exploration and the evaluation of coal bed gas resources located in coalfields.展开更多
When boost power factor correction(PFC) circuit works with large scale load fluctuations, it is easy to cause a higher total harmonic distortion and a lower power factor because of traditional controllers and inductor...When boost power factor correction(PFC) circuit works with large scale load fluctuations, it is easy to cause a higher total harmonic distortion and a lower power factor because of traditional controllers and inductor current mode. To solve this problem, this paper proposes a PFC control system, which can operate with load fluctuations up to 1 000 W by using duty cycle feed-forward control theory to achieve smooth switching mode. The duty cycles in the next period of the control system are pre-estimated in the current cycle, which enhances the speeds of AD samplers and switching frequency, and reduces the cost and volume of the equipment to some extent. Introductions of system decoupling and feed-forward of input-voltage greatly improve the system performance. Both theoretical simulation and experimental results prove the advantage of the proposed scheme.展开更多
The seismic data from western China is very noisy. Two main reasons are static corrections and low S/N ratio problems. By seismic data processing and study these problems have been effectively solved by iterating the ...The seismic data from western China is very noisy. Two main reasons are static corrections and low S/N ratio problems. By seismic data processing and study these problems have been effectively solved by iterating the static corrections and improving the S/N ratio for pre-stack seismic data. Suppression and elimination of various other distortions has been implemented as well. Due to the fact that the S/N ratio is improved, the resolution of the seismic data is also improved.展开更多
Mixed integer linear programming （MILP） approach for simultaneous gross error detection and data reconciliation has been proved as an efficient way to adjust process data with material, energy, and other balance con...Mixed integer linear programming （MILP） approach for simultaneous gross error detection and data reconciliation has been proved as an efficient way to adjust process data with material, energy, and other balance constrains. But the efficiency will decrease significantly when this method is applled in a large-scale problem because there are too many binary variables involved. In this article, an improved method is proposed in order to gen- erate gross error candidates with reliability factors before data rectification. Candidates are used in the MILP objec- tive function to improve the efficiency and accuracy by reducing the number of binary variables and giving accurate weights for suspected gross errors candidates. Performance of this improved method is compared and discussed by applying the algorithm in a widely used industrial example.展开更多
Data reconciliation technology can decrease the level of corruption of process data due to measurement noise, but the presence of outliers caused by process peaks or unmeasured disturbances will smear the reconciled r...Data reconciliation technology can decrease the level of corruption of process data due to measurement noise, but the presence of outliers caused by process peaks or unmeasured disturbances will smear the reconciled results. Based on the analysis of limitation of conventional outlier detection algorithms, a modified outlier detection method in dynamic data reconciliation (DDR) is proposed in this paper. In the modified method, the outliers of each variable are distinguished individually and the weight is modified accordingly. Therefore, the modified method can use more information of normal data, and can efficiently decrease the effect of outliers. Simulation of a continuous stirred tank reactor (CSTR) process verifies the effectiveness of the proposed algorithm.展开更多
文摘A bandgap voltage reference is presented with a piecewise linear compensating circuit in order to reduce the temperature coefficient.The basic principle is to divide the whole operating temperature range into some sub ranges.At different temperature sub ranges the bandgap reference can be compensated by different linear functions.Since the temperature sub range is much narrower than the whole range,the compensation error can be reduced significantly.Theoretically,the precision can be improved unlimitedly if the sub ranges are narrow enough.In the given example,with only three temperature sub ranges,the temperature coefficient of a conventional bandgap reference drops from 1 5×10 -5 /℃ to 2×10 -6 /℃ over the -40℃ to 120℃ temperature range.
文摘By summing geophone and hydrophone data with opposite polarity responses to water layer reverberation,the ocean bottom cable dual-sensor acquisition technique can effectively eliminate reverberation,broaden the frequency bandwidth,and improve both the resolution and fidelity of the seismic data.It is thus widely used in industry.However,it is difficult to ensure good coupling of the geophones with the seabed because of the impact of ocean flow,seafloor topography,and field operations;therefore,geophone data are seriously affected by the transfer function of the geophone-seabed coupling system.As a result,geophone data frequently have low signal-to-noise ratios（S/N）,which causes large differences in amplitude,frequency,and phases between geophone and hydrophone data that severely affect dual-sensor summation.In contrast,the hydrophone detects changes in brine pressure and has no coupling issues with the seabed;thus,hydrophone data always have good S/N.First,in this paper,the mathematical expression of the transfer function between geophone and seabed is presented.Second,the transfer function of the geophone-seabed is estimated using hydrophone data as reference traces,and finally,the coupling correction based on the estimated transfer function is implemented.Using this processing,the amplitude and phase differences between geophone and hydrophone data are removed,and the S/N of the geophone data are improved.Synthetic and real data examples then show that our method is feasible and practical.
文摘A new approach for rules-based optical proximity correction is presented.The discussion addresses on how to select and construct more concise and practical rules-base as well as how to apply that rules-base.Based on those ideas,several primary rules are suggested.The v-support vector regression method is used to generate a mathematical expression according to rule data.It enables to make correction according to any given rules parameters.Experimental results demonstrate applying rules calculated from the expression match well with that from the rule table.
基金supported by the Important National Science&Technology Specific Projects(No.2011ZX05019-003)the New Method and Technology Research Project of Geophysical Exploration of CNPC(No.2014A-3612)
文摘Stacking velocity V_（C2）,vertical velocity ratio γ_0,effective velocity ratio γ_（eff）,and anisotropic parameter x_（eff） are correlated in the PS-converted-wave（PS-wave） anisotropic prestack Kirchhoff time migration（PKTM） velocity model and are thus difficult to independently determine.We extended the simplified two-parameter（stacking velocity V_（C2） and anisotropic parameter k_（eff）） moveout equation from stacking velocity analysis to PKTM velocity model updating and formed a new four-parameter（stacking velocity V_（C2）,vertical velocity ratio γ_0,effective velocity ratio γ_（eff）,and anisotropic parameter k_（eff）） PS-wave anisotropic PKTM velocity model updating and process flow based on the simplified twoparameter moveout equation.In the proposed method,first,the PS-wave two-parameter stacking velocity is analyzed to obtain the anisotropic PKTM initial velocity and anisotropic parameters;then,the velocity and anisotropic parameters are corrected by analyzing the residual moveout on common imaging point gathers after prestack time migration.The vertical velocity ratio γ_0 of the prestack time migration velocity model is obtained with an appropriate method utilizing the P- and PS-wave stacked sections after level calibration.The initial effective velocity ratio γ_（eff） is calculated using the Thomsen（1999） equation in combination with the P-wave velocity analysis;ultimately,the final velocity model of the effective velocity ratio γ_（eff） is obtained by percentage scanning migration.This method simplifies the PS-wave parameter estimation in high-quality imaging,reduces the uncertainty of multiparameter estimations,and obtains good imaging results in practice.
基金Supported by the Funds for 0utstanding Young Researchers from the National Natural Science Foundation of China （No.60025308） and the Key Technologies R＆D Program in the National ＂10th 5-year Plan＂ （No.2001BA204B07）.
文摘Data reconciliation is an effective technique for providing accurate and consistent value for chemical process. However, the presence of gross errors can severely bias the reconciled results. Robust estimators can significantly reduce the effect of gross errors and yield less-biased results. In this article, a new method is proposed to solve the robust data reconciliation problem of nonlinear chemical process. By using several technologies including linearization method, penalty function, virtual observation equation, and equivalent weights method, the robust data reconciliation problem can be transformed into least squares estimator problem which leads to the convenience in computation. Simulation results in a nonlinear chemical process demonstrate the efficiency of the proposed method.
基金Funded by the National 973 Program of China (No. 2006CB701301)the Basic Research of Geomatics and Geodesy of the Key Laboratory of Geo-space Environment and Geodesy, Ministry of Education, China (No. 03-04-10)the Project of University Education and Research of Hubei Province(No.20053039).
文摘In the past few years, network RTK positioning technology, especially the VRS technology, has been widely used in some parts of China and in many countries around the world. The principle of the VRS technology is discussed with corresponding formula deduction, and detailed descriptions and applications of VRS corrections and virtual observations generation algorithm are given.
基金Supported by the National Natural Science Foundation of China （No.60504033）
文摘Outlier in one variable will smear the estimation of other measurements in data reconciliation （DR）. In this article, a novel robust method is proposed for nonlinear dynamic data reconciliation, to reduce the influence of outliers on the result of DR. This method introduces a penalty function matrix in a conventional least-square objective function, to assign small weights for outliers and large weights for normal measurements. To avoid the loss of data information, element-wise Mahalanobis distance is proposed, as an improvement on vector-wise distance, to construct a penalty function matrix. The correlation of measurement error is also considered in this article. The method introduces the robust statistical theory into conventional least square estimator by constructing the penalty weight matrix and gets not only good robustness but also simple calculation. Simulation of a continuous stirred tank reactor, verifies the effectiveness of the proposed algorithm.
基金Supported by the National Creative Research Groups Science Foundation of China (No.60421002) and the National "TenthFive-Year" Science and Technology Research Program of China (2004BA204B08).
文摘An NT-MT combined method based on nodal test (NT) and measurement test (MT) is developed for gross error detection and data reconciliation for industrial application. The NT-MT combined method makes use of both NT and MT tests and this combination helps to overcome the defects in the respective methods. It also avoids any artificial manipulation and eliminates the huge combinatorial problem that is created in the combined method based on the nodal test in the case of more than one gross error for a large process system. Serial compensation strategy is also used to avoid the decrease of the coefficient matrix rank during the computation of the proposed method. Simulation results show that the proposed method is very effective and possesses good performance.
基金supported by the National Basic Research Program of China (No. 2009CB219605)the National Natural Science Foundation of China (Nos. 40730422 and 40872104)
文摘Improving the accuracy and precision of coal bed methane(CBM) estimates requires correction of older data from older coal exploration surveys to newer standards.Three methods,the depth gradient method,the contour aerial weight method,and the well-point aerial weight method,were used to estimate the correction coefficient required to predict CBM gas content from coal exploration data.The data from the Nos.3 and 15 coal seams provided the coal exploration data while the CBM exploration stages within the X1 well block located in the southern part of the Qinshui Basin provided the data obtained using newer standards.The results show the correction coefficients obtained from the two aerial weight methods are similar in value but lower than the one obtained from the depth gradient method.The three methods provide similar results for the Nos.3 and 15 seams in that the correction factor is lower for the former seam.The results from the depth gradient method taken together with the coal seam burial depth and the coal rank suggest that variations in the correction factor increase linearly along with coal seam burial depth and coal rank.The correlation obtained can be applied to exploration and the evaluation of coal bed gas resources located in coalfields.
基金Supported by the National Basic Research Program of China("973"Program,No.2009CB219700)
文摘When boost power factor correction(PFC) circuit works with large scale load fluctuations, it is easy to cause a higher total harmonic distortion and a lower power factor because of traditional controllers and inductor current mode. To solve this problem, this paper proposes a PFC control system, which can operate with load fluctuations up to 1 000 W by using duty cycle feed-forward control theory to achieve smooth switching mode. The duty cycles in the next period of the control system are pre-estimated in the current cycle, which enhances the speeds of AD samplers and switching frequency, and reduces the cost and volume of the equipment to some extent. Introductions of system decoupling and feed-forward of input-voltage greatly improve the system performance. Both theoretical simulation and experimental results prove the advantage of the proposed scheme.
文摘The seismic data from western China is very noisy. Two main reasons are static corrections and low S/N ratio problems. By seismic data processing and study these problems have been effectively solved by iterating the static corrections and improving the S/N ratio for pre-stack seismic data. Suppression and elimination of various other distortions has been implemented as well. Due to the fact that the S/N ratio is improved, the resolution of the seismic data is also improved.
基金Supported by the National High Technology Research and Development Program of China (2007AA40702 and 2007AA04Z191)
文摘Mixed integer linear programming （MILP） approach for simultaneous gross error detection and data reconciliation has been proved as an efficient way to adjust process data with material, energy, and other balance constrains. But the efficiency will decrease significantly when this method is applled in a large-scale problem because there are too many binary variables involved. In this article, an improved method is proposed in order to gen- erate gross error candidates with reliability factors before data rectification. Candidates are used in the MILP objec- tive function to improve the efficiency and accuracy by reducing the number of binary variables and giving accurate weights for suspected gross errors candidates. Performance of this improved method is compared and discussed by applying the algorithm in a widely used industrial example.
基金Supported by the National Outstanding Youth Science Foundation of China (No. 60025308) and Key Technologies R&DProgram in the 10th Five-year Plan (No. 2001BA204B07)
文摘Data reconciliation technology can decrease the level of corruption of process data due to measurement noise, but the presence of outliers caused by process peaks or unmeasured disturbances will smear the reconciled results. Based on the analysis of limitation of conventional outlier detection algorithms, a modified outlier detection method in dynamic data reconciliation (DDR) is proposed in this paper. In the modified method, the outliers of each variable are distinguished individually and the weight is modified accordingly. Therefore, the modified method can use more information of normal data, and can efficiently decrease the effect of outliers. Simulation of a continuous stirred tank reactor (CSTR) process verifies the effectiveness of the proposed algorithm.
