The purpose of this study was to investigate the hydrolyzation of aspirin during the process of dissolution testing for aspirin delayed-release tablets. Hydrolysis product of salicylic acid can result in adverse effec...The purpose of this study was to investigate the hydrolyzation of aspirin during the process of dissolution testing for aspirin delayed-release tablets. Hydrolysis product of salicylic acid can result in adverse effects and affect the determination of dissolution rate assaying. In this study, the technique of differential spectra was employed, which made it possible to monitor the dissolution testing in situ. The results showed that the hydrolyzation of aspirin made the percentage of salicylic acid exceed the limit of free salicylic acid （4.0）, and the hydrolyzation may affect the quality detection of aspirin delayed-release tablets.展开更多
[ Objective ] This study aimed to optimize the extraction process of astaxanthin from Haematococcus pluvialis with oil dissolution method. [ Method ] Small amounts of acetone or ethanol were separately added into soyb...[ Objective ] This study aimed to optimize the extraction process of astaxanthin from Haematococcus pluvialis with oil dissolution method. [ Method ] Small amounts of acetone or ethanol were separately added into soybean oil for astaxanthin extraction. The extraction efficiency of astaxanthin from H. pluvialis with different methods was compared. [ Result] The extraction efficiency of astaxanthin from H. pluvialis with acetone, acetone ＋ soybean oil, ethanol ＋ soybean oil, soybean oil was 20.46, 21.65, 20.85 mg/g and 13.05 mg/g, respectively. According to the results, acetone ＋ soybean oil led to the highest extraction rate, which was approximately twice that of soybean oil and higher than that of acetone. [ Conclusion ] This study laid the foundation for large-scale production of astaxanthin.展开更多
This article is concerned with the numerical investigation of one-dimensional population balance models for batch crystallization process with fines dissolution.In batch crystallization,dissolution of smaller unwanted...This article is concerned with the numerical investigation of one-dimensional population balance models for batch crystallization process with fines dissolution.In batch crystallization,dissolution of smaller unwanted nuclei below some critical size is of vital importance as it improves the quality of product.The crystal growth rates for both size-independent and size-dependent cases are considered.A delay in recycle pipe is also included in the model.The space–time conservation element and solution element method,originally derived for non-reacting flows,is used to solve the model.This scheme has already been applied to a range of PDEs,mainly in the area of fluid mechanics.The numerical results are compared with those obtained from the Koren scheme,showing that the proposed scheme is more efficient.展开更多
In view of the limited space of offshore platform and the large amount of polymer injection, the dissolution time method, solution viscosity method, conductivity method, undissolved filtration method and falling ball ...In view of the limited space of offshore platform and the large amount of polymer injection, the dissolution time method, solution viscosity method, conductivity method, undissolved filtration method and falling ball method are used as the rapid detection methods of polymer dissolution. The results show that the error of conductivity method is the largest, and that of dissolution time method is the second, and both methods are time-consuming. Solution viscosity method and insolubles filtration method have small error, but they are time-consuming, especially for offshore platforms, which makes detection inconvenient. The drop ball method is simple in operation and has a small error, so it is a promising method for rapid determination of polymer dissolution time.展开更多
Objective: to analyze the influence of different dissolution evaluation methods on the level of pharmaceutical preparations, and to sort out the application strategies for improving the level of pharmaceutical prepara...Objective: to analyze the influence of different dissolution evaluation methods on the level of pharmaceutical preparations, and to sort out the application strategies for improving the level of pharmaceutical preparations. Methods: 100 paracetamol tablets were screened out and then divided into 2 groups according to the blind selection method, specifically referring to: the observation group and the control group, each group is 50 tablets, among which, the observation group selected 0.04%NaOH solution as the dissolution medium, and then the dissolution was evaluated;In the control group, phosphate buffer with PH 6.8 was selected as the dissolution medium, and then the dissolution was evaluated. The dissolution amount and dissolution percentage (80%) of the two groups were determined separately. Results: in terms of the changes of dissolution volume, percentage of dissolution and other indicators, the observation group far exceeded the control group. However, in terms of the average dissolution time, the observation group was significantly smaller than the control group, and the difference between the two groups was significant, with a statistical advantage (P < 0.05). Conclusion: since the evaluation methods of dissolution are different, there are obvious differences in the changes in the level of pharmaceutical preparations. If the level of pharmaceutical preparations is to be gradually improved, the best dissolution evaluation method must be selected before the corresponding test results can be obtained.展开更多
A comprehensive heat and mass transfer model of dissolution process of non-agglomerated and agglomerated alumina particles was established in an aluminum reduction cell. An appropriate finite difference method was use...A comprehensive heat and mass transfer model of dissolution process of non-agglomerated and agglomerated alumina particles was established in an aluminum reduction cell. An appropriate finite difference method was used to calculate the size dissolution rate, dissolution time and mass of alumina dissolved employing commercial software and custom algorithm based on the shrinking sphere assumption. The effects of some convection and thermal condition parameters on the dissolution process were studied. The calculated results show that the decrease of alumina content or the increase of alumina diffusion coefficient is beneficial for the increase of size dissolution rate and the decrease of dissolution time of non-agglomerated particles. The increase of bath superheat or alumina preheating temperature results in the increase of size dissolution rate and the decrease of dissolution time of agglomerated particles. The calculated dissolution curve of alumina（mass fraction of alumina dissolved） for a 300 k A aluminum reduction cell is in well accordance with the experimental results. The analysis shows that the dissolution process of alumina can be divided into two distinct stages： the fast dissolution stage of non-agglomerated particles and the slow dissolution stage of agglomerated particles, with the dissolution time in the order of 10 and 100 s, respectively. The agglomerated particles were identified to be the most important factor limiting the dissolution process.展开更多
Enhanced oil recovery(EOR)by means of polymer flooding is an important technology for the strategic development of offshore oilfields in China.Hydrophobically associating polyacrylamide(HAPAM)has been recently propose...Enhanced oil recovery(EOR)by means of polymer flooding is an important technology for the strategic development of offshore oilfields in China.Hydrophobically associating polyacrylamide(HAPAM)has been recently proposed as a new flooding agent.The solubility of HAPAM is low,which is the bottleneck for further improving the oil recovery through polymer flooding in offshore oilfield.Stirred tanks have been used on offshore platforms to enhance HAPAM dissolving.But there is little literature on the study of HAPAM dissolving characteristics in stirred tanks.In this paper,effects of temperature,salinity,stirring speed,impeller type and stirring method on the dissolution of HAPAM are reported.The experimental results manifest that the dissolving rate of HAPAM increases with temperature and stirring speed,but the viscosity of the polymer solution decreases.There is an optimal range of salinity for polymer dissolving.Combining the operation mode of up-pumping with varying stirring speed,hydrofoil impeller can accelerate the dissolution of HAPAM and maintain a high solution viscosity.展开更多
Berberine hydrochloride is commonly used to treat bacterial dysentery,gastroenteritis and other diseases.Many manufacturers are available on the market today,while the production process and formulation are quite diff...Berberine hydrochloride is commonly used to treat bacterial dysentery,gastroenteritis and other diseases.Many manufacturers are available on the market today,while the production process and formulation are quite different,which may directly affect the therapeutic effect of the drug.To this end,11 different production producers of berberine hydrochloride tablets were collected according to the pharmacopeia berberine hydrochloride dissolution method(basket method).In addition the dissolution process was carried out in four elution media with different pH,and the difference was similar(f2).Factors were calculated to evaluate in vitro dissolution requirements,and in vitro dissolution of different manufacturers of berberine hydrochloride tablets was determined by high performance liquid chromatography(HPLC).The method was verified by linearity,precision,stability and robustness.Based on the f2 value,there was a significant difference in the dissolution behavior of the formulations of most berberine hydrochloride tablet brands.This research provided the basis for further in-depth research in the later period.Although the drug specifications(0.1 g)were the same,the dissolution curve was different.This phenomenon may be attributed to the fact that the excipients and crystal form of the tablets affected the release and dissolution of the tablets in vitro.展开更多
In this study,using mesoporous silica for the solubility enhancement of poorly watersoluble drug was investigated.Although the incorporating drug into mesoporous silica is generally performed through the solvent meth...In this study,using mesoporous silica for the solubility enhancement of poorly watersoluble drug was investigated.Although the incorporating drug into mesoporous silica is generally performed through the solvent method,the new melting method was proposed in the present study.Fenofibrate,a poorly water-soluble drug,was incorporated into mesoporous silica by solvent method and melting method.The obtained samples were observed by SEM and their physicochemical properties were evaluated by PXRD and DSC measurement.The dissolution and supersaturated property were also investigated.The results from SEM,PXRD and DSC measurement showed that drug could be loaded into pore via the melting method as well as by the solvent method.The drug loaded quantity depended on the pore volume.Drug up to 33%could be incorporated into mesoporous silica and existed in amorphous state.When drug was overloaded or difficulty in incorporation into pore was found,recrystallization of drug occurred at the outer surface of mesoporous silica.From the dissolution test,samples prepared by solvent method and melting method gave the supersaturated drug concentration which sample from melting method showed superior dissolution to the one from solvent method.From this study,drug was efficiently incorporated into mesoporous silica by the melting method which is a simple and solvent-free process,and the aqueous solubility enhancement of poorly watersoluble drug was achieved.展开更多
Counterfeit medicines are a growing problem in both developing and industrialised countries. In general the evaluation of these medicines is limited to the identification and the dosage of the active ingredients. In t...Counterfeit medicines are a growing problem in both developing and industrialised countries. In general the evaluation of these medicines is limited to the identification and the dosage of the active ingredients. In this study in vitro dissolution tests were conducted on two sets of counterfeit medicines containing PDE-5 inhibitors （sildenafil citrate and tadalafil）. The dissolution profiles were statistically compared to the ones of the genuine products using the f2-method and a comparison at each time point using the Cochran test. The results showed low equivalences between counterfeit and genuine products as well as higher variations around the mean dissolution value at the different time points for the counterfeit products.展开更多
This paper presents the results from using a physical absorption process to absorb gaseous CO2mixed with N2using water by producing tiny bubbles via a liquid-film-forming device（LFFD）that improves the solubility of ...This paper presents the results from using a physical absorption process to absorb gaseous CO2mixed with N2using water by producing tiny bubbles via a liquid-film-forming device（LFFD）that improves the solubility of CO2in water.The influence of various parameters—pressure,initial CO2concentration,gas-to-liquid ratios,and temperature—on the CO2removal efficiency and its absorption rate in water were investigated and estimated thoroughly by statistical polynomial models obtained by the utilization of the response surface method（RSM）with a central composite design（CCD）.Based on the analysis,a high efficiency of CO2capture can be reached in conditions such as low pressure,high CO2concentration at the inlet,low gas/liquid ratio,and low temperature.For instance,the highest removal efficiency in the RSM–CCD experimental matrix of nearly 80%occurred for run number 20,which was conducted at 0.30 MPa,CO2concentration of 35%,gas/liquid ratio of 0.71,and temperature of 15℃.Furthermore,the coefficients of determination,R^2,were 0.996 for the removal rate and 0.982 for the absorption rate,implying that the predicted values computed by the constructed models correlate strongly and fit well with the experimental values.The results obtained provide essential information for implementing this method properly and effectively and contribute a promising approach to the problem of CO2capture in air pollution treatment.展开更多
Aimed at improving the bias stability of Fiber-Optic Gyroscope(FOG)-based inertial navigation systems in environments of various ambient temperatures,a novel temperaturecompensation method based on a correlation analy...Aimed at improving the bias stability of Fiber-Optic Gyroscope(FOG)-based inertial navigation systems in environments of various ambient temperatures,a novel temperaturecompensation method based on a correlation analysis of the same batch of FOGs is proposed.The empirical mode decomposition method was employed to filter the high-frequency noises of the FOGs.Then,the correlation information of the multiple FOGs was used to analyze the feasibility of the method.Eventually,the same residual error of the FOGs was compensated via the simple piecewise linear models.The experimental results indicate that excellent compensation effects for both high-and low-accuracy FOGs are achieved using the proposed method.Specifically,the accuracies of high-accuracy FOGs are improved by approximately 33.9%,20%,and 31.2%,while those of low-accuracy FOGs are improved by approximately 39.1%,20.8%,and 26.1%.The method exhibits the merits of simplicity,validity,and stability,and thus is expected to be widely used in engineering applications.展开更多
In the realm of acoustic signal detection,the identification of weak signals,particularly in the presence of negative signal-to-noise ratios,poses a significant challenge.This challenge is further heightened when sign...In the realm of acoustic signal detection,the identification of weak signals,particularly in the presence of negative signal-to-noise ratios,poses a significant challenge.This challenge is further heightened when signals are acquired through fiber-optic hydrophones,as these signals often lack physical significance and resist clear systematic modeling.Conventional processing methods,e.g.,low-pass filter(LPF),require a thorough understanding of the effective signal bandwidth for noise reduction,and may introduce undesirable time lags.This paper introduces an innovative feedback control method with dual Kalman filters for the demodulation of phase signals with noises in fiber-optic hydrophones.A mathematical model of the closed-loop system is established to guide the design of the feedback control,aiming to achieve a balance with the input phase signal.The dual Kalman filters are instrumental in mitigating the effects of signal noise,observation noise,and control execution noise,thereby enabling precise estimation for the input phase signals.The effectiveness of this feedback control method is demonstrated through examples,showcasing the restoration of low-noise signals,negative signal-to-noise ratio signals,and multi-frequency signals.This research contributes to the technical advancement of high-performance devices,including fiber-optic hydrophones and phase-locked amplifiers.展开更多
基金supported by the Xinjiang Medical University Scientific Innovation Fund (No. XJC201129)Xinjiang Uygur Autonomous Region Natural Science Fund (No. 2011211A041)
文摘The purpose of this study was to investigate the hydrolyzation of aspirin during the process of dissolution testing for aspirin delayed-release tablets. Hydrolysis product of salicylic acid can result in adverse effects and affect the determination of dissolution rate assaying. In this study, the technique of differential spectra was employed, which made it possible to monitor the dissolution testing in situ. The results showed that the hydrolyzation of aspirin made the percentage of salicylic acid exceed the limit of free salicylic acid （4.0）, and the hydrolyzation may affect the quality detection of aspirin delayed-release tablets.
基金Supported by Project of Yantai Huarong Biological Technology Co.,Ltd
文摘[ Objective ] This study aimed to optimize the extraction process of astaxanthin from Haematococcus pluvialis with oil dissolution method. [ Method ] Small amounts of acetone or ethanol were separately added into soybean oil for astaxanthin extraction. The extraction efficiency of astaxanthin from H. pluvialis with different methods was compared. [ Result] The extraction efficiency of astaxanthin from H. pluvialis with acetone, acetone ＋ soybean oil, ethanol ＋ soybean oil, soybean oil was 20.46, 21.65, 20.85 mg/g and 13.05 mg/g, respectively. According to the results, acetone ＋ soybean oil led to the highest extraction rate, which was approximately twice that of soybean oil and higher than that of acetone. [ Conclusion ] This study laid the foundation for large-scale production of astaxanthin.
文摘This article is concerned with the numerical investigation of one-dimensional population balance models for batch crystallization process with fines dissolution.In batch crystallization,dissolution of smaller unwanted nuclei below some critical size is of vital importance as it improves the quality of product.The crystal growth rates for both size-independent and size-dependent cases are considered.A delay in recycle pipe is also included in the model.The space–time conservation element and solution element method,originally derived for non-reacting flows,is used to solve the model.This scheme has already been applied to a range of PDEs,mainly in the area of fluid mechanics.The numerical results are compared with those obtained from the Koren scheme,showing that the proposed scheme is more efficient.
文摘In view of the limited space of offshore platform and the large amount of polymer injection, the dissolution time method, solution viscosity method, conductivity method, undissolved filtration method and falling ball method are used as the rapid detection methods of polymer dissolution. The results show that the error of conductivity method is the largest, and that of dissolution time method is the second, and both methods are time-consuming. Solution viscosity method and insolubles filtration method have small error, but they are time-consuming, especially for offshore platforms, which makes detection inconvenient. The drop ball method is simple in operation and has a small error, so it is a promising method for rapid determination of polymer dissolution time.
文摘Objective: to analyze the influence of different dissolution evaluation methods on the level of pharmaceutical preparations, and to sort out the application strategies for improving the level of pharmaceutical preparations. Methods: 100 paracetamol tablets were screened out and then divided into 2 groups according to the blind selection method, specifically referring to: the observation group and the control group, each group is 50 tablets, among which, the observation group selected 0.04%NaOH solution as the dissolution medium, and then the dissolution was evaluated;In the control group, phosphate buffer with PH 6.8 was selected as the dissolution medium, and then the dissolution was evaluated. The dissolution amount and dissolution percentage (80%) of the two groups were determined separately. Results: in terms of the changes of dissolution volume, percentage of dissolution and other indicators, the observation group far exceeded the control group. However, in terms of the average dissolution time, the observation group was significantly smaller than the control group, and the difference between the two groups was significant, with a statistical advantage (P < 0.05). Conclusion: since the evaluation methods of dissolution are different, there are obvious differences in the changes in the level of pharmaceutical preparations. If the level of pharmaceutical preparations is to be gradually improved, the best dissolution evaluation method must be selected before the corresponding test results can be obtained.
基金Project(2010AA065201)supported by the High-tech Research and Development Program of ChinaProject(2013zzts038)supported by the Fundamental Research Funds for the Central Universities of Central South University,ChinaProject(ZB2011CBBCe1)supported by the Major Program for Aluminum Corporation of China Limited
文摘A comprehensive heat and mass transfer model of dissolution process of non-agglomerated and agglomerated alumina particles was established in an aluminum reduction cell. An appropriate finite difference method was used to calculate the size dissolution rate, dissolution time and mass of alumina dissolved employing commercial software and custom algorithm based on the shrinking sphere assumption. The effects of some convection and thermal condition parameters on the dissolution process were studied. The calculated results show that the decrease of alumina content or the increase of alumina diffusion coefficient is beneficial for the increase of size dissolution rate and the decrease of dissolution time of non-agglomerated particles. The increase of bath superheat or alumina preheating temperature results in the increase of size dissolution rate and the decrease of dissolution time of agglomerated particles. The calculated dissolution curve of alumina（mass fraction of alumina dissolved） for a 300 k A aluminum reduction cell is in well accordance with the experimental results. The analysis shows that the dissolution process of alumina can be divided into two distinct stages： the fast dissolution stage of non-agglomerated particles and the slow dissolution stage of agglomerated particles, with the dissolution time in the order of 10 and 100 s, respectively. The agglomerated particles were identified to be the most important factor limiting the dissolution process.
文摘Enhanced oil recovery(EOR)by means of polymer flooding is an important technology for the strategic development of offshore oilfields in China.Hydrophobically associating polyacrylamide(HAPAM)has been recently proposed as a new flooding agent.The solubility of HAPAM is low,which is the bottleneck for further improving the oil recovery through polymer flooding in offshore oilfield.Stirred tanks have been used on offshore platforms to enhance HAPAM dissolving.But there is little literature on the study of HAPAM dissolving characteristics in stirred tanks.In this paper,effects of temperature,salinity,stirring speed,impeller type and stirring method on the dissolution of HAPAM are reported.The experimental results manifest that the dissolving rate of HAPAM increases with temperature and stirring speed,but the viscosity of the polymer solution decreases.There is an optimal range of salinity for polymer dissolving.Combining the operation mode of up-pumping with varying stirring speed,hydrofoil impeller can accelerate the dissolution of HAPAM and maintain a high solution viscosity.
基金National Institutes for Food and Drug Control(Grant No.017ZX09101001).
文摘Berberine hydrochloride is commonly used to treat bacterial dysentery,gastroenteritis and other diseases.Many manufacturers are available on the market today,while the production process and formulation are quite different,which may directly affect the therapeutic effect of the drug.To this end,11 different production producers of berberine hydrochloride tablets were collected according to the pharmacopeia berberine hydrochloride dissolution method(basket method).In addition the dissolution process was carried out in four elution media with different pH,and the difference was similar(f2).Factors were calculated to evaluate in vitro dissolution requirements,and in vitro dissolution of different manufacturers of berberine hydrochloride tablets was determined by high performance liquid chromatography(HPLC).The method was verified by linearity,precision,stability and robustness.Based on the f2 value,there was a significant difference in the dissolution behavior of the formulations of most berberine hydrochloride tablet brands.This research provided the basis for further in-depth research in the later period.Although the drug specifications(0.1 g)were the same,the dissolution curve was different.This phenomenon may be attributed to the fact that the excipients and crystal form of the tablets affected the release and dissolution of the tablets in vitro.
文摘In this study,using mesoporous silica for the solubility enhancement of poorly watersoluble drug was investigated.Although the incorporating drug into mesoporous silica is generally performed through the solvent method,the new melting method was proposed in the present study.Fenofibrate,a poorly water-soluble drug,was incorporated into mesoporous silica by solvent method and melting method.The obtained samples were observed by SEM and their physicochemical properties were evaluated by PXRD and DSC measurement.The dissolution and supersaturated property were also investigated.The results from SEM,PXRD and DSC measurement showed that drug could be loaded into pore via the melting method as well as by the solvent method.The drug loaded quantity depended on the pore volume.Drug up to 33%could be incorporated into mesoporous silica and existed in amorphous state.When drug was overloaded or difficulty in incorporation into pore was found,recrystallization of drug occurred at the outer surface of mesoporous silica.From the dissolution test,samples prepared by solvent method and melting method gave the supersaturated drug concentration which sample from melting method showed superior dissolution to the one from solvent method.From this study,drug was efficiently incorporated into mesoporous silica by the melting method which is a simple and solvent-free process,and the aqueous solubility enhancement of poorly watersoluble drug was achieved.
文摘Counterfeit medicines are a growing problem in both developing and industrialised countries. In general the evaluation of these medicines is limited to the identification and the dosage of the active ingredients. In this study in vitro dissolution tests were conducted on two sets of counterfeit medicines containing PDE-5 inhibitors （sildenafil citrate and tadalafil）. The dissolution profiles were statistically compared to the ones of the genuine products using the f2-method and a comparison at each time point using the Cochran test. The results showed low equivalences between counterfeit and genuine products as well as higher variations around the mean dissolution value at the different time points for the counterfeit products.
基金the support of the Ministry of Education, Culture, Sports, Science, and Technology of Japan (MEXT – Monbukagakusho Scholarship)Yashima Environment Technology Foundation
文摘This paper presents the results from using a physical absorption process to absorb gaseous CO2mixed with N2using water by producing tiny bubbles via a liquid-film-forming device（LFFD）that improves the solubility of CO2in water.The influence of various parameters—pressure,initial CO2concentration,gas-to-liquid ratios,and temperature—on the CO2removal efficiency and its absorption rate in water were investigated and estimated thoroughly by statistical polynomial models obtained by the utilization of the response surface method（RSM）with a central composite design（CCD）.Based on the analysis,a high efficiency of CO2capture can be reached in conditions such as low pressure,high CO2concentration at the inlet,low gas/liquid ratio,and low temperature.For instance,the highest removal efficiency in the RSM–CCD experimental matrix of nearly 80%occurred for run number 20,which was conducted at 0.30 MPa,CO2concentration of 35%,gas/liquid ratio of 0.71,and temperature of 15℃.Furthermore,the coefficients of determination,R^2,were 0.996 for the removal rate and 0.982 for the absorption rate,implying that the predicted values computed by the constructed models correlate strongly and fit well with the experimental values.The results obtained provide essential information for implementing this method properly and effectively and contribute a promising approach to the problem of CO2capture in air pollution treatment.
基金supported by the Young Scientists Fund,China(No.62103021).
文摘Aimed at improving the bias stability of Fiber-Optic Gyroscope(FOG)-based inertial navigation systems in environments of various ambient temperatures,a novel temperaturecompensation method based on a correlation analysis of the same batch of FOGs is proposed.The empirical mode decomposition method was employed to filter the high-frequency noises of the FOGs.Then,the correlation information of the multiple FOGs was used to analyze the feasibility of the method.Eventually,the same residual error of the FOGs was compensated via the simple piecewise linear models.The experimental results indicate that excellent compensation effects for both high-and low-accuracy FOGs are achieved using the proposed method.Specifically,the accuracies of high-accuracy FOGs are improved by approximately 33.9%,20%,and 31.2%,while those of low-accuracy FOGs are improved by approximately 39.1%,20.8%,and 26.1%.The method exhibits the merits of simplicity,validity,and stability,and thus is expected to be widely used in engineering applications.
基金Project supported by the National Key Research and Development Program of China(No.2022YFB3203600)the National Natural Science Foundation of China(Nos.12172323,12132013+1 种基金12332003)the Zhejiang Provincial Natural Science Foundation of China(No.LZ22A020003)。
文摘In the realm of acoustic signal detection,the identification of weak signals,particularly in the presence of negative signal-to-noise ratios,poses a significant challenge.This challenge is further heightened when signals are acquired through fiber-optic hydrophones,as these signals often lack physical significance and resist clear systematic modeling.Conventional processing methods,e.g.,low-pass filter(LPF),require a thorough understanding of the effective signal bandwidth for noise reduction,and may introduce undesirable time lags.This paper introduces an innovative feedback control method with dual Kalman filters for the demodulation of phase signals with noises in fiber-optic hydrophones.A mathematical model of the closed-loop system is established to guide the design of the feedback control,aiming to achieve a balance with the input phase signal.The dual Kalman filters are instrumental in mitigating the effects of signal noise,observation noise,and control execution noise,thereby enabling precise estimation for the input phase signals.The effectiveness of this feedback control method is demonstrated through examples,showcasing the restoration of low-noise signals,negative signal-to-noise ratio signals,and multi-frequency signals.This research contributes to the technical advancement of high-performance devices,including fiber-optic hydrophones and phase-locked amplifiers.
