The abundance of live and dead Oithona similis in Jiaozhou Bay,Shandong,China,was investigated monthly from December 2008 to November 2009 via the neutral red staining method.The annual variation in total abundance wa...The abundance of live and dead Oithona similis in Jiaozhou Bay,Shandong,China,was investigated monthly from December 2008 to November 2009 via the neutral red staining method.The annual variation in total abundance was similar for females,males,and copepodites,with a main numerical peak from February to July and a minor peak in November,but the variations in carcass abundance and death proportion were different.The monthly average abundance of male and copepodite carcasses significantly increased with their total abundance(P<0.001),whereas no such correlation was observed for females.The abundance of female carcasses peaked at 12.4 inds./m^(3) in November but remained below 3.0 inds./m^(3) in all other months.The monthly average death proportion ranged 0.3%-4.9% for females,3.6%-25.7% for males,and 2.6%-8.4% for copepodites.On average,the death proportion of males was 9.2 times greater than that of females and 3.5 times greater than that of copepodites.Therefore,significant sexual difference exists in the non-predatory mortality of O.similis and this difference is an important cause of the female-skewed sex ratios observed in the field.展开更多
Magnetization convenience is crucial consideration for design of valve magnetic actuators.The existing repulsive-magnetic-coupling of 2D maglev valve is not oriented to the integral-magnetization-processes,resulting i...Magnetization convenience is crucial consideration for design of valve magnetic actuators.The existing repulsive-magnetic-coupling of 2D maglev valve is not oriented to the integral-magnetization-processes,resulting in the high assembly cost.This paper presents a novel tractive-magnetic-coupling(TMC)and its application on a 2D electro-hydraulic proportional flow valve(2D-EHPFV),whose configuration not only fulfill the requirements of 2D valve,but also oriented to integral-magnetization-process.To investigate the output torque of TMC,a detailed analytical model considering leakage flux,edge effect and tooth magnetic saturation is formulated based on the equivalent magnetic circuit method.To facilitate the magnetic saturation calculation,a special magnetic permeability database is established for tooth region of TMC using Ansoft/Maxwell software.Prototype of TMC is machined and an exclusive experimental platform is built.Torque-displacement characteristics under different working airgap and tooth number are measured.The experimental results are in good agreement with the analytical results,which verifies the correctness of the analytical model.Then the TMC is integrated into the 2D-EHPFV by replacing the repulsive-magnetic-coupling.Prototype of 2D-EHPFV is designed and manufactured to test the no-load flow characteristics,load flow characteristics,leakage characteristics,frequency characteristics and step response.Under working pressure of 15 MPa,the maximum no-load flow rate is 82.2 L/min with the hysteresis of 2.6%,and the amplitude and phase frequency width is 21.6 Hz,and 28.9 Hz.The detailed experimental results show that TMC can be applied to 2D valves to form 2D-EHPFV,which can reduce hysteresis and cost,and improve response speed.展开更多
This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial...This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial and resonant disturbances.In this estimator structure,referred to as Cascade GPIO(CGPIO),the total disturbance sensitivity is the product of the sensitivities at each cascade level.This approach improves system performance against both periodic and non-periodic disturbances and enhances robustness under frequency variations in harmonic components.Additionally,the decoupled nature of the estimator reduces the order of the GPIOs,thereby simplifying tuning and limiting observer gains.The proposed control scheme is supported by a frequency-domain analysis and is experimentally validated in the current control of a grid-connected converter subject to control gain uncertainties,harmonic distortion,frequency deviations,and measurement noise.Experimental results demonstrate that the CGPIO-based ADRC outperforms benchmark solutions,including proportional-integral(PI)and proportional-resonant(PR)controllers.展开更多
The purpose of this paper is to design control loop and guidance loop for the homing missile, to prove that the modified variable structure proportional navigation (VSPN) can be used in passive homing guidance system,...The purpose of this paper is to design control loop and guidance loop for the homing missile, to prove that the modified variable structure proportional navigation (VSPN) can be used in passive homing guidance system, and to compare the VSPN with the proportional navigation (PN). Angular rate and linear acceleration are fed back to improve the stability and robust of autopilot, VSPN and PN are compared in mathematics simulation of homing missile in attacking tanks and helicopters. The damp and the stability of the missile body are increased. The VSPN cuts down the overload of guidance phase dramatically, makes the ballistic trajectory straighter than PN and leads to smaller missdistance. The VSPN can be used for passive homing guidance system, and is especially suitable for attacking helicopter.展开更多
A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control...A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control pressure and flow is suggested. By using very simpleproportional throttle valve in structure, the functions that five kinds of proportional valves orany two of them combined possess can be complimented. After analyzing, comparing, and testing thedynamic and static characteristics of valve with different controlling principles and main valvestructure styles, the optimized structure styles and control methods are achieved.展开更多
Proportional and derivative kick i.e., a large change in control action of a proportional plus integral plus derivative （PID） controller due to a sudden change in reference set-point is generally undesired in proces...Proportional and derivative kick i.e., a large change in control action of a proportional plus integral plus derivative （PID） controller due to a sudden change in reference set-point is generally undesired in process industry. Therefore, the structure of conventional parallel PID controller is modified to integral minus proportional derivative （I-PD） controller. In this paper, three hybrid fuzzy IPD controllers such as a fuzzy I-fuzzy PD （FI-FPD） controller and its hybrid combinations with its conventional counterpart such as fuzzy I-PD （FI-PD） and I-fuzzy PD （I-FPD） are presented in view of above industrial problem. These controllers are based upon the counterpart conventional I-PD controller and contains analytical formulae. Computer simulations are carried out to evaluate the performance of hybrid fuzzy controllers along with conventional I-PD and PID controllers for set-point tracking and disturbance rejection for an induction motor in closed loop using LabVIEWTM environment. The gains of conventional and hybrid fuzzy controllers are tuned using genetic algorithm （GA） for minimum overshoot and settling time. It has been observed that hybrid fuzzy controllers along with the conventional I-PD controller significantly remove the kick from the control action in reference set-point tracking. However, in disturbance rejection, I-PD and FI-PD controllers fail to eliminate the kick from the control signal. In contrast, FI-FPD and I-FPD controllers considerably reduced spikes from the control action in disturbance rejection. Among the conventional and hybrid fuzzy IPD controllers, FI--FPD demonstrates much better set-point tracking and disturbance rejection response with spike free control action.展开更多
In order to evaluate the reliability of long-lifetime products with degradation data, a new proportional hazard degradation model is proposed. By the similarity between time-degradation data and stress-accelerated lif...In order to evaluate the reliability of long-lifetime products with degradation data, a new proportional hazard degradation model is proposed. By the similarity between time-degradation data and stress-accelerated lifetime, and the failure rate function of degradation data which is assumed to be proportional to the time covariate, the reliability assessment based on a proportional hazard degradation model is realized. The least squares method is used to estimate the model＇s parameters. Based on the failure rate of the degradation data and the proportion function of the known time, the failure rate and the reliability function under the given time and the predetermined failure threshold can be extrapolated. A long life GaAs laser is selected as a case study and its reliability is evaluated. The results show that the proposed method can accurately describe the degradation process and it is effective for the reliability assessment of long lifetime products.展开更多
[Objective] This study aimed to examine the effect of different proportions of Wolffia on the growth of Procambarus clarkia in 2 kinds of community scales. [Method] Six proportions of baits mixed by watermeal and comm...[Objective] This study aimed to examine the effect of different proportions of Wolffia on the growth of Procambarus clarkia in 2 kinds of community scales. [Method] Six proportions of baits mixed by watermeal and commercial feed (0, 20%, 40%, 60%, 80%, and 100%) were designed to feed the Procambarus clarkia juveniles in 2 community scales to research the growth situation of the crayfish in different mixed baits. The growth differences between the minimal community and the larger community of crayfish in the same proportion of Wolffia were compared. [Result] The growth situations of crayfish in the 2 community scales at different proportions of watermeal were as follows: the body length was the longest in 60% watermeal group, and shortest in the pure watermeal group; the regularity was the best in the 20% watermeal group; no matter the minimal community or the larger community, there was no significant difference in the survival rate between different watermeal proportions. The growth situations of crayfish in the 2 community scales at specific proportion of watermeal were: the average body length of the minimal community was significantly greater than the larger community, and the survival rate also greater than the latter one, but the difference was not significant. [Conclusion] Considering all kinds of index such as growth, survival rate, regularity, the appropriate proportion of the baits mixed by watermeal and commercial feed is 40% to 60%; big community scale has significant inhibition on growth of crayfish, thus, there should be barriers when cultivating Procambarus clarkia juvenile.展开更多
Aim Aiming at the position tracking control for valve controlled motor electrohydraulic proportional servo systems mainly driving the static load torque, the tracking performance was studied in the presence of the v...Aim Aiming at the position tracking control for valve controlled motor electrohydraulic proportional servo systems mainly driving the static load torque, the tracking performance was studied in the presence of the variable gain and deadzone. Methods On the basis of conventional composite control with the deadzone compensation method, a comprehensive control approach with the deadzone and self adjusting feedforward compensation was proposed. Results Experimental results showed that the good tracking performance was achieved for the sinusoidal and constant velocity position tracking under a wide variations of load torque. Conclusion The position tracking accuracy for valve controlled motor electrohydraulic proportional servo systems has been solved by using the comprehensive control approach with the deadzone and self adjusting feedforward compensation.展开更多
A new proportional navigation(PN) guidance law,called combined proportional navigation(CPN),is proposed.The guidance law is designed to intercept high-speed targets,which is a common case for ballistic targets.The ran...A new proportional navigation(PN) guidance law,called combined proportional navigation(CPN),is proposed.The guidance law is designed to intercept high-speed targets,which is a common case for ballistic targets.The range of target-to-interceptor speed ratio during target interception is derived when guidance laws are applied in high-speed targets interception,and the effectiveness of negative navigation ratio in the PN-based guidance law is proven analytically in some lemmas.Based on the lemmas,the lateral acceleration command of CPN is defined,and the solution to the appearance of singularity in time-varying navigation ratio is given.The simulation results show that CPN can determine headon engagement(as PN) or tail-chase engagement(as RPN) through initial path angle compared with PN and retro proportional navigation(RPN),and can adjust the value of navigation ratio for head-on engagement or tail-chase engagement.Therefore,the capture region of CPN is larger than that of other guidance laws using PN-based methods.展开更多
Proportioning is an important part of sintering,as it affects the cost of sintering and the quality of sintered ore.To address the problems posed by the complex raw material information and numerous constraints in the...Proportioning is an important part of sintering,as it affects the cost of sintering and the quality of sintered ore.To address the problems posed by the complex raw material information and numerous constraints in the sintering process,a multi-objective optimisation model for sintering proportioning was established,which takes the proportioning cost and TFe as the optimisation objectives.Additionally,an improved multi-objective beluga whale optimisation(IMOBWO)algorithm was proposed to solve the nonlinear,multi-constrained multi-objective optimisation problems.The algorithm uses the con-strained non-dominance criterion to deal with the constraint problem in the model.Moreover,the algorithm employs an opposite learning strategy and a population guidance mechanism based on angular competition and two-population competition strategy to enhance convergence and population diversity.The actual proportioning of a steel plant indicates that the IMOBWO algorithm applied to the ore proportioning process has good convergence and obtains the uniformly distributed Pareto front.Meanwhile,compared with the actual proportioning scheme,the proportioning cost is reduced by 4.3361¥/t,and the TFe content in the mixture is increased by 0.0367%in the optimal compromise solution.Therefore,the proposed method effectively balances the cost and total iron,facilitating the comprehensive utilisation of sintered iron ore resources while ensuring quality assurance.展开更多
An accelerated proportional degradation hazards-odds model is proposed. It is a non-parametric model and thus has path- free and distribution-free properties, avoiding the errors caused by faulty assumptions of degrad...An accelerated proportional degradation hazards-odds model is proposed. It is a non-parametric model and thus has path- free and distribution-free properties, avoiding the errors caused by faulty assumptions of degradation paths or distribution of degra- dation measurements. It is established based on a link function which combines the degradation cumulative hazard rate function and the degradation odds function through a transformation pa- rameter, and this makes the accelerated proportional degradation hazards model and the accelerated proportional degradation odds model special cases of it. Hypothesis tests are discussed, and the proposed model is applicable when some model assumptions are satisfied. This model is utilized to estimate the reliability of minia- ture bulbs under low stress levels based on the degradation data obtained under high stress levels to validate the effectiveness of this model.展开更多
Aim In accordance with the positioning control for valve controlled motor electrohydraulic proportional servo systems driving the static load torque, the positioning performance was studied in the presence of the ti...Aim In accordance with the positioning control for valve controlled motor electrohydraulic proportional servo systems driving the static load torque, the positioning performance was studied in the presence of the time? varying deadzone and gain. Methods The large positioning errors caused by the time varying deadzone were significantly reduced by using the dynamic compensation method for the deadzone; and the large overshoot caused by the time varying gain were dramatically reduced by using the three section intelligent control schemes. Results Experimental results demonstrated that the positioning performance of rapid response, high accuracy and smaller or even no overshoot was achieved under a wide variations of load torque. Conclusion The good positioning performance for valve controlled motor servo systems has been achieved in the presence of the time varying deadzone and gain.展开更多
In this paper after analyzing the adaptation process of the proportionate normalized least mean square(PNLMS) algorithm, a statistical model is obtained to describe the convergence process of each adaptive filter coef...In this paper after analyzing the adaptation process of the proportionate normalized least mean square(PNLMS) algorithm, a statistical model is obtained to describe the convergence process of each adaptive filter coefcient. Inspired by this result, a modified PNLMS algorithm based on precise magnitude estimate is proposed. The simulation results indicate that in contrast to the traditional PNLMS algorithm, the proposed algorithm achieves faster convergence speed in the initial convergence state and lower misalignment in the stead stage with much less computational complexity.展开更多
rate,ratio,proportion三词都可以表示“比例”。表此义时,其差别甚是微妙,值得注意。现作如下辨析: rate指“比、比率、比例”,如:mortality rate死亡率,tax rate税率,rate of rejects废品率,rate of attendance出勤率,crime rate犯罪...rate,ratio,proportion三词都可以表示“比例”。表此义时,其差别甚是微妙,值得注意。现作如下辨析: rate指“比、比率、比例”,如:mortality rate死亡率,tax rate税率,rate of rejects废品率,rate of attendance出勤率,crime rate犯罪率,divorce rate离婚率,accident rate事故发生率。从以上例证不难看出,这里所谓的“比、比率”是指部分相对整体形成的比率,即a mea-sure of a part with respect to the whole。如“废品率”是产品“总量”减去“正品量”然后除以总量而得来的。展开更多
To investigate the effects of different ratios of ropivacaine on the anesthetic effect of cesarean section.. Methods: 60 cases of parturient undergoing caesarean section from January 2020 to March 2022 were selected a...To investigate the effects of different ratios of ropivacaine on the anesthetic effect of cesarean section.. Methods: 60 cases of parturient undergoing caesarean section from January 2020 to March 2022 were selected and divided into two groups: control group (N 30) , ropivacaine observation group (N 30), contrast effect. Results: the blood pressure and heart rate of the observation group were better than those of the control group (P 0.05);the pain score of the observation group was lower than that of the control group (P 0.05);the effective rate of the observation group was 96.67% , the pain score of the Observation Group was lower than that of the control group (P Lt;0.05) , the blood pressure and heart rate of the observation group were higher than those of the control group (P 0.05);the pain score of the observation group were lower than those of the control group (P 0.05);the incidence of adverse reactions was 3.33%, which was lower than 20.00% of the control group (P 0.05). Conclusion: isobaric ropivacaine is effective and safe in cesarean section anesthesia, and can increase the comfort of parturient.展开更多
The COVID-19 pandemic has brought legal challenges to the containment measures adopted by European countries.During the outbreak and containment phase of the pandemic,most European countries adopted measures such as l...The COVID-19 pandemic has brought legal challenges to the containment measures adopted by European countries.During the outbreak and containment phase of the pandemic,most European countries adopted measures such as lockdowns and mandatory home quarantines based on the principle of risk prevention.However,Article 15 of the European Convention on Human Rights and judgments by the European Court of Human Rights require such measures to comply with the principle of proportionality.In view of this,this article examines the European Court of Justice’s loose judgments on the derogation measures during the pandemic,and the European Court of Human Rights’situational judgments in this regard.Based on the analysis of the legitimacy of the principle of risk prevention and the principle of proportionality in responding to public health emergencies,this article prudently examines and predicts the trend of applying the principle of proportionality of risk prevention for the European COVID-19 derogation measures from three perspectives of legitimacy,necessity,and feasibility.展开更多
The objective is to design a variable structure proportional navigation law for the passive homingmissile so that the missile can hit the target with a minimum miss-distance and desired impact attitude anglewithin the...The objective is to design a variable structure proportional navigation law for the passive homingmissile so that the missile can hit the target with a minimum miss-distance and desired impact attitude anglewithin the required overlcad when it flies at a lower trajectory.This paper utilized the variable structure propor-tional navigation with terminal impact attitude angular constraint,and made estimation about the distance rateand distance between the missile and target,which broke the limitation of a passive homing seeker.Furthermore,the paper let the switch gain vary adaptively with time to avoid any larger initial overload.The mathematicalsimulation was completed by some studied passive homing missile's dynamic model,and the simulation resultsshowed that the navigation law of the passive homing missile can make the missile get the required miss-distance and desired impact attitude angle against tanks at lower trajectories and within the maximum overload;also this guidance law is much robust to the estimation eror of distance and distance rate.展开更多
A mathematic model is built up to analyze the influences of a pilot valve'sleakage on the performances of pneumatic pressure proportional valve, and the performances aresimulated by using MATLAB. The results indic...A mathematic model is built up to analyze the influences of a pilot valve'sleakage on the performances of pneumatic pressure proportional valve, and the performances aresimulated by using MATLAB. The results indicate that using slide pilot valve in the valve system isfeasible, but the leakage's influences can not be neglected, especially it may induce instability ina low output pressure situation. A pilot valve using too large throttle window will cause the valveoscillate. To improve the working condition of pilot valve, a method adopting different widths oftwo throttle window is proposed. According to our simulation, this method balances the pressure dropbetween the two stage throttle ports, and reduces the influences of pilot valve's leakage.展开更多
A feasible guidance scheme with impact time constraint is proposed for attacking a stationary target by missiles with time-varying velocity.The main idea is to replace the constant velocity with the future mean veloci...A feasible guidance scheme with impact time constraint is proposed for attacking a stationary target by missiles with time-varying velocity.The main idea is to replace the constant velocity with the future mean velocity;therefore, the existing time-to-go estimation algorithm of the proportional navigation guidance law can be improved to adapt to varying conditions.In order to obtain the prediction of the velocity profile, the velocity differential equation to the downrange is derived, which can be numerically integrated between the current downrange and the target position by the on-board computer.Then, a third-order polynomial is introduced to fit the velocity profile in order to calculate the future mean velocity.At the beginning of each guidance loop, the future mean velocity is predicted and the time-to-go information is updated, based on which a novel biased proportional navigation guidance law is established to achieve the impact time constraint.Finally,numerical simulation results verified the effectiveness of the time-to-go estimation algorithm and the proposed law.展开更多
基金Supported by the Shandong Provincial Natural Science Foundation(No.ZR2020QC043)。
文摘The abundance of live and dead Oithona similis in Jiaozhou Bay,Shandong,China,was investigated monthly from December 2008 to November 2009 via the neutral red staining method.The annual variation in total abundance was similar for females,males,and copepodites,with a main numerical peak from February to July and a minor peak in November,but the variations in carcass abundance and death proportion were different.The monthly average abundance of male and copepodite carcasses significantly increased with their total abundance(P<0.001),whereas no such correlation was observed for females.The abundance of female carcasses peaked at 12.4 inds./m^(3) in November but remained below 3.0 inds./m^(3) in all other months.The monthly average death proportion ranged 0.3%-4.9% for females,3.6%-25.7% for males,and 2.6%-8.4% for copepodites.On average,the death proportion of males was 9.2 times greater than that of females and 3.5 times greater than that of copepodites.Therefore,significant sexual difference exists in the non-predatory mortality of O.similis and this difference is an important cause of the female-skewed sex ratios observed in the field.
基金Supported by National Natural Science Foundation of China(Grant Nos.51975524,52375067)Zhejiang Provincial Natural Science Foundation of China(Grant No.Y23E050014).
文摘Magnetization convenience is crucial consideration for design of valve magnetic actuators.The existing repulsive-magnetic-coupling of 2D maglev valve is not oriented to the integral-magnetization-processes,resulting in the high assembly cost.This paper presents a novel tractive-magnetic-coupling(TMC)and its application on a 2D electro-hydraulic proportional flow valve(2D-EHPFV),whose configuration not only fulfill the requirements of 2D valve,but also oriented to integral-magnetization-process.To investigate the output torque of TMC,a detailed analytical model considering leakage flux,edge effect and tooth magnetic saturation is formulated based on the equivalent magnetic circuit method.To facilitate the magnetic saturation calculation,a special magnetic permeability database is established for tooth region of TMC using Ansoft/Maxwell software.Prototype of TMC is machined and an exclusive experimental platform is built.Torque-displacement characteristics under different working airgap and tooth number are measured.The experimental results are in good agreement with the analytical results,which verifies the correctness of the analytical model.Then the TMC is integrated into the 2D-EHPFV by replacing the repulsive-magnetic-coupling.Prototype of 2D-EHPFV is designed and manufactured to test the no-load flow characteristics,load flow characteristics,leakage characteristics,frequency characteristics and step response.Under working pressure of 15 MPa,the maximum no-load flow rate is 82.2 L/min with the hysteresis of 2.6%,and the amplitude and phase frequency width is 21.6 Hz,and 28.9 Hz.The detailed experimental results show that TMC can be applied to 2D valves to form 2D-EHPFV,which can reduce hysteresis and cost,and improve response speed.
文摘This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial and resonant disturbances.In this estimator structure,referred to as Cascade GPIO(CGPIO),the total disturbance sensitivity is the product of the sensitivities at each cascade level.This approach improves system performance against both periodic and non-periodic disturbances and enhances robustness under frequency variations in harmonic components.Additionally,the decoupled nature of the estimator reduces the order of the GPIOs,thereby simplifying tuning and limiting observer gains.The proposed control scheme is supported by a frequency-domain analysis and is experimentally validated in the current control of a grid-connected converter subject to control gain uncertainties,harmonic distortion,frequency deviations,and measurement noise.Experimental results demonstrate that the CGPIO-based ADRC outperforms benchmark solutions,including proportional-integral(PI)and proportional-resonant(PR)controllers.
文摘The purpose of this paper is to design control loop and guidance loop for the homing missile, to prove that the modified variable structure proportional navigation (VSPN) can be used in passive homing guidance system, and to compare the VSPN with the proportional navigation (PN). Angular rate and linear acceleration are fed back to improve the stability and robust of autopilot, VSPN and PN are compared in mathematics simulation of homing missile in attacking tanks and helicopters. The damp and the stability of the missile body are increased. The VSPN cuts down the overload of guidance phase dramatically, makes the ballistic trajectory straighter than PN and leads to smaller missdistance. The VSPN can be used for passive homing guidance system, and is especially suitable for attacking helicopter.
基金This project is supported by National Natural Science Foundation of China (No.50275102)Provincial Foundation for Abroad Return People of Shanxi (No.101045).
文摘A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control pressure and flow is suggested. By using very simpleproportional throttle valve in structure, the functions that five kinds of proportional valves orany two of them combined possess can be complimented. After analyzing, comparing, and testing thedynamic and static characteristics of valve with different controlling principles and main valvestructure styles, the optimized structure styles and control methods are achieved.
文摘Proportional and derivative kick i.e., a large change in control action of a proportional plus integral plus derivative （PID） controller due to a sudden change in reference set-point is generally undesired in process industry. Therefore, the structure of conventional parallel PID controller is modified to integral minus proportional derivative （I-PD） controller. In this paper, three hybrid fuzzy IPD controllers such as a fuzzy I-fuzzy PD （FI-FPD） controller and its hybrid combinations with its conventional counterpart such as fuzzy I-PD （FI-PD） and I-fuzzy PD （I-FPD） are presented in view of above industrial problem. These controllers are based upon the counterpart conventional I-PD controller and contains analytical formulae. Computer simulations are carried out to evaluate the performance of hybrid fuzzy controllers along with conventional I-PD and PID controllers for set-point tracking and disturbance rejection for an induction motor in closed loop using LabVIEWTM environment. The gains of conventional and hybrid fuzzy controllers are tuned using genetic algorithm （GA） for minimum overshoot and settling time. It has been observed that hybrid fuzzy controllers along with the conventional I-PD controller significantly remove the kick from the control action in reference set-point tracking. However, in disturbance rejection, I-PD and FI-PD controllers fail to eliminate the kick from the control signal. In contrast, FI-FPD and I-FPD controllers considerably reduced spikes from the control action in disturbance rejection. Among the conventional and hybrid fuzzy IPD controllers, FI--FPD demonstrates much better set-point tracking and disturbance rejection response with spike free control action.
基金The National Natural Science Foundation of China (No.50405021)
文摘In order to evaluate the reliability of long-lifetime products with degradation data, a new proportional hazard degradation model is proposed. By the similarity between time-degradation data and stress-accelerated lifetime, and the failure rate function of degradation data which is assumed to be proportional to the time covariate, the reliability assessment based on a proportional hazard degradation model is realized. The least squares method is used to estimate the model＇s parameters. Based on the failure rate of the degradation data and the proportion function of the known time, the failure rate and the reliability function under the given time and the predetermined failure threshold can be extrapolated. A long life GaAs laser is selected as a case study and its reliability is evaluated. The results show that the proposed method can accurately describe the degradation process and it is effective for the reliability assessment of long lifetime products.
文摘[Objective] This study aimed to examine the effect of different proportions of Wolffia on the growth of Procambarus clarkia in 2 kinds of community scales. [Method] Six proportions of baits mixed by watermeal and commercial feed (0, 20%, 40%, 60%, 80%, and 100%) were designed to feed the Procambarus clarkia juveniles in 2 community scales to research the growth situation of the crayfish in different mixed baits. The growth differences between the minimal community and the larger community of crayfish in the same proportion of Wolffia were compared. [Result] The growth situations of crayfish in the 2 community scales at different proportions of watermeal were as follows: the body length was the longest in 60% watermeal group, and shortest in the pure watermeal group; the regularity was the best in the 20% watermeal group; no matter the minimal community or the larger community, there was no significant difference in the survival rate between different watermeal proportions. The growth situations of crayfish in the 2 community scales at specific proportion of watermeal were: the average body length of the minimal community was significantly greater than the larger community, and the survival rate also greater than the latter one, but the difference was not significant. [Conclusion] Considering all kinds of index such as growth, survival rate, regularity, the appropriate proportion of the baits mixed by watermeal and commercial feed is 40% to 60%; big community scale has significant inhibition on growth of crayfish, thus, there should be barriers when cultivating Procambarus clarkia juvenile.
文摘Aim Aiming at the position tracking control for valve controlled motor electrohydraulic proportional servo systems mainly driving the static load torque, the tracking performance was studied in the presence of the variable gain and deadzone. Methods On the basis of conventional composite control with the deadzone compensation method, a comprehensive control approach with the deadzone and self adjusting feedforward compensation was proposed. Results Experimental results showed that the good tracking performance was achieved for the sinusoidal and constant velocity position tracking under a wide variations of load torque. Conclusion The position tracking accuracy for valve controlled motor electrohydraulic proportional servo systems has been solved by using the comprehensive control approach with the deadzone and self adjusting feedforward compensation.
文摘A new proportional navigation(PN) guidance law,called combined proportional navigation(CPN),is proposed.The guidance law is designed to intercept high-speed targets,which is a common case for ballistic targets.The range of target-to-interceptor speed ratio during target interception is derived when guidance laws are applied in high-speed targets interception,and the effectiveness of negative navigation ratio in the PN-based guidance law is proven analytically in some lemmas.Based on the lemmas,the lateral acceleration command of CPN is defined,and the solution to the appearance of singularity in time-varying navigation ratio is given.The simulation results show that CPN can determine headon engagement(as PN) or tail-chase engagement(as RPN) through initial path angle compared with PN and retro proportional navigation(RPN),and can adjust the value of navigation ratio for head-on engagement or tail-chase engagement.Therefore,the capture region of CPN is larger than that of other guidance laws using PN-based methods.
基金supported by the National Key Research and Development Program of China (2022YFB3304700)Hunan Province Natural Science Foundation (2022JJ50132,2022JCYJ05 and 2022JCYJ09).
文摘Proportioning is an important part of sintering,as it affects the cost of sintering and the quality of sintered ore.To address the problems posed by the complex raw material information and numerous constraints in the sintering process,a multi-objective optimisation model for sintering proportioning was established,which takes the proportioning cost and TFe as the optimisation objectives.Additionally,an improved multi-objective beluga whale optimisation(IMOBWO)algorithm was proposed to solve the nonlinear,multi-constrained multi-objective optimisation problems.The algorithm uses the con-strained non-dominance criterion to deal with the constraint problem in the model.Moreover,the algorithm employs an opposite learning strategy and a population guidance mechanism based on angular competition and two-population competition strategy to enhance convergence and population diversity.The actual proportioning of a steel plant indicates that the IMOBWO algorithm applied to the ore proportioning process has good convergence and obtains the uniformly distributed Pareto front.Meanwhile,compared with the actual proportioning scheme,the proportioning cost is reduced by 4.3361¥/t,and the TFe content in the mixture is increased by 0.0367%in the optimal compromise solution.Therefore,the proposed method effectively balances the cost and total iron,facilitating the comprehensive utilisation of sintered iron ore resources while ensuring quality assurance.
基金supported by the postdoctoral funding at Tsinghua University
文摘An accelerated proportional degradation hazards-odds model is proposed. It is a non-parametric model and thus has path- free and distribution-free properties, avoiding the errors caused by faulty assumptions of degradation paths or distribution of degra- dation measurements. It is established based on a link function which combines the degradation cumulative hazard rate function and the degradation odds function through a transformation pa- rameter, and this makes the accelerated proportional degradation hazards model and the accelerated proportional degradation odds model special cases of it. Hypothesis tests are discussed, and the proposed model is applicable when some model assumptions are satisfied. This model is utilized to estimate the reliability of minia- ture bulbs under low stress levels based on the degradation data obtained under high stress levels to validate the effectiveness of this model.
文摘Aim In accordance with the positioning control for valve controlled motor electrohydraulic proportional servo systems driving the static load torque, the positioning performance was studied in the presence of the time? varying deadzone and gain. Methods The large positioning errors caused by the time varying deadzone were significantly reduced by using the dynamic compensation method for the deadzone; and the large overshoot caused by the time varying gain were dramatically reduced by using the three section intelligent control schemes. Results Experimental results demonstrated that the positioning performance of rapid response, high accuracy and smaller or even no overshoot was achieved under a wide variations of load torque. Conclusion The good positioning performance for valve controlled motor servo systems has been achieved in the presence of the time varying deadzone and gain.
文摘In this paper after analyzing the adaptation process of the proportionate normalized least mean square(PNLMS) algorithm, a statistical model is obtained to describe the convergence process of each adaptive filter coefcient. Inspired by this result, a modified PNLMS algorithm based on precise magnitude estimate is proposed. The simulation results indicate that in contrast to the traditional PNLMS algorithm, the proposed algorithm achieves faster convergence speed in the initial convergence state and lower misalignment in the stead stage with much less computational complexity.
文摘rate,ratio,proportion三词都可以表示“比例”。表此义时,其差别甚是微妙,值得注意。现作如下辨析: rate指“比、比率、比例”,如:mortality rate死亡率,tax rate税率,rate of rejects废品率,rate of attendance出勤率,crime rate犯罪率,divorce rate离婚率,accident rate事故发生率。从以上例证不难看出,这里所谓的“比、比率”是指部分相对整体形成的比率,即a mea-sure of a part with respect to the whole。如“废品率”是产品“总量”减去“正品量”然后除以总量而得来的。
文摘To investigate the effects of different ratios of ropivacaine on the anesthetic effect of cesarean section.. Methods: 60 cases of parturient undergoing caesarean section from January 2020 to March 2022 were selected and divided into two groups: control group (N 30) , ropivacaine observation group (N 30), contrast effect. Results: the blood pressure and heart rate of the observation group were better than those of the control group (P 0.05);the pain score of the observation group was lower than that of the control group (P 0.05);the effective rate of the observation group was 96.67% , the pain score of the Observation Group was lower than that of the control group (P Lt;0.05) , the blood pressure and heart rate of the observation group were higher than those of the control group (P 0.05);the pain score of the observation group were lower than those of the control group (P 0.05);the incidence of adverse reactions was 3.33%, which was lower than 20.00% of the control group (P 0.05). Conclusion: isobaric ropivacaine is effective and safe in cesarean section anesthesia, and can increase the comfort of parturient.
基金the National Social Science Fund of China’s major project“Research on Legislation and Categorization in Emergencies”(20&ZD175)the National Social Science Fund of China’s project“Research on the Relationship between Constitution and International Law”(18BFX034)
文摘The COVID-19 pandemic has brought legal challenges to the containment measures adopted by European countries.During the outbreak and containment phase of the pandemic,most European countries adopted measures such as lockdowns and mandatory home quarantines based on the principle of risk prevention.However,Article 15 of the European Convention on Human Rights and judgments by the European Court of Human Rights require such measures to comply with the principle of proportionality.In view of this,this article examines the European Court of Justice’s loose judgments on the derogation measures during the pandemic,and the European Court of Human Rights’situational judgments in this regard.Based on the analysis of the legitimacy of the principle of risk prevention and the principle of proportionality in responding to public health emergencies,this article prudently examines and predicts the trend of applying the principle of proportionality of risk prevention for the European COVID-19 derogation measures from three perspectives of legitimacy,necessity,and feasibility.
文摘The objective is to design a variable structure proportional navigation law for the passive homingmissile so that the missile can hit the target with a minimum miss-distance and desired impact attitude anglewithin the required overlcad when it flies at a lower trajectory.This paper utilized the variable structure propor-tional navigation with terminal impact attitude angular constraint,and made estimation about the distance rateand distance between the missile and target,which broke the limitation of a passive homing seeker.Furthermore,the paper let the switch gain vary adaptively with time to avoid any larger initial overload.The mathematicalsimulation was completed by some studied passive homing missile's dynamic model,and the simulation resultsshowed that the navigation law of the passive homing missile can make the missile get the required miss-distance and desired impact attitude angle against tanks at lower trajectories and within the maximum overload;also this guidance law is much robust to the estimation eror of distance and distance rate.
基金This project is supported by National Natural Science Foundation of China (No.50122115)the National 10th Five Years Plan Special Research Programs of China(No.2003BA408B14).
文摘A mathematic model is built up to analyze the influences of a pilot valve'sleakage on the performances of pneumatic pressure proportional valve, and the performances aresimulated by using MATLAB. The results indicate that using slide pilot valve in the valve system isfeasible, but the leakage's influences can not be neglected, especially it may induce instability ina low output pressure situation. A pilot valve using too large throttle window will cause the valveoscillate. To improve the working condition of pilot valve, a method adopting different widths oftwo throttle window is proposed. According to our simulation, this method balances the pressure dropbetween the two stage throttle ports, and reduces the influences of pilot valve's leakage.
文摘A feasible guidance scheme with impact time constraint is proposed for attacking a stationary target by missiles with time-varying velocity.The main idea is to replace the constant velocity with the future mean velocity;therefore, the existing time-to-go estimation algorithm of the proportional navigation guidance law can be improved to adapt to varying conditions.In order to obtain the prediction of the velocity profile, the velocity differential equation to the downrange is derived, which can be numerically integrated between the current downrange and the target position by the on-board computer.Then, a third-order polynomial is introduced to fit the velocity profile in order to calculate the future mean velocity.At the beginning of each guidance loop, the future mean velocity is predicted and the time-to-go information is updated, based on which a novel biased proportional navigation guidance law is established to achieve the impact time constraint.Finally,numerical simulation results verified the effectiveness of the time-to-go estimation algorithm and the proposed law.
