A feedback control method for phase signal demodulation in fber-optic hydrophones

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.

Cooperative trajectory optimization of UAVs in approaching stage using feedback guidance methods

This paper mainly studies the problem of using UAVs to provide accurate remote target indication for hypersonic projectiles.Based on the optimal trajectory trends and feedback guidance methods,a new cooperative control algorithm is proposed to optimize trajectories of multi-UAVs for target tracking in approaching stage.Based on UAV kinematics and sensor performance models,optimal trajectory trends of UAVs are analyzed theoretically.Then,feedback guidance methods are proposed under the optimal observation trends of UAVs in the approaching target stage,producing trajectories with far less computational complexity and performance very close to the best-known trajectories.Next,the sufficient condition for the UAV to form the optimal observation configuration by the feedback guidance method is presented,which guarantees that the proposed method can optimize the observation trajectory of the UAV in approaching stage.Finally,the feedback guidance method is numerically simulated.Simulation results demonstrate that the estimation performance of the feedback guidance method is superior to the Lyapunov guidance vector field(LGVF)method and verify the effectiveness of the proposed method.Additionally,compared with the receding horizon optimization(RHO)method,the proposed method has the same optimization ability as the RHO method and better real-time performance.

Effectiveness of one-to-one feedback methods of teaching with proper metered-dose inhaler technique and correcting errors in chronic obstructive lung disease patients

Objective:To determine the most common mistakes made during the use of a metered-dose inhaler(MDI),and the effect of the repeated trainings performed with demonstration method by providing one-to-one feedback on these mistakes.Methods:This is a quasi-experimental study with a control group.A total of 100 chronic obstructive pulmonary disease(COPD)patients(50 in the control group and 50 in the experimental group)were included in the research.“Patient Information Form(PIF)”(to determine the descriptive characteristics of patients)through the face-to-face interview method,using“MDI Skill Assessment Form”(MDISAF)(it is composed of 10 skill steps about the use of MDI)through observation method was used.Patients in both the groups were asked to use MDI and their abilities regarding use of MDI were assessed.Then in the intervention group,usage of MDI was explained by a nurse via demonstration and placebo MDI.Trainings were repeated on days 1,3,and 5 as from hospitalization of the patient.In the intervention group,three methods were used in this study:“face-to-face training,”“one-to-one,”and“with feedbacks and repeated.”Routine training regarding use of MDI was given by the nurses in the clinic to patients in the control group.The use of an MDI was assessed using MDISAF before training and after the training on the first,third and fifth days of hospitalization.On the seventh day,the last measurement was performed.Percentage,chi square,and mean were used to assess the data.Results:After repetitive training with one-to-one feedback,several differences between the groups in favor of the experimental group were found in 7 of the 10 skill levels of the MDI.There was a significant difference after“training”between the groups in the third,fourth,fifth,sixth,seventh,eighth and ninth MDI steps in posttest measurement(P<0.05).Evaluating the skills of the groups to use MDI from pretest to posttest,it was determined that while the intervention group made less mistakes in steps in which mistakes were made mostly,the control group continued to make mistakes.Conclusions:Inhaler technique intervention with repeated,face to face,and one-to-one feedback trainings can significantly enhance the MDI techniques in COPD patients.The patients in the intervention group made less mistakes during MDI application and their application skills improved.It may be asser ted that the training provided to the intervention group was effective for using the device correctly,while the training provided in the clinic for the control group was inadequate.

Performance enhancement of a viscoelastic bistable energy harvester using time-delayed feedback control

This paper focuses on the stochastic analysis of a viscoelastic bistable energy harvesting system under colored noise and harmonic excitation, and adopts the time-delayed feedback control to improve its harvesting efficiency. Firstly, to obtain the dimensionless governing equation of the system, the original bistable system is approximated as a system without viscoelastic term by using the stochastic averaging method of energy envelope, and then is further decoupled to derive an equivalent system. The credibility of the proposed method is validated by contrasting the consistency between the numerical and the analytical results of the equivalent system under different noise conditions. The influence of system parameters on average output power is analyzed, and the control effect of the time-delayed feedback control on system performance is compared. The output performance of the system is improved with the occurrence of stochastic resonance(SR). Therefore, the signal-to-noise ratio expression for measuring SR is derived, and the dependence of its SR behavior on different parameters is explored.

NOVEL IMMERSED BOUNDARY-LATTICE BOLTZMANN METHOD BASED ON FEEDBACK LAW

The lattice Boltzmann method （LBM） and the immersed boundary method （IBM） are alternative, com- putational techniques for solving complex fluid dynamics systems, and can take the place of the Navier-Stokes（N- S） equation. This paper proposes a novel immersed boundary-lattice Boltzmann method （IB-LBM） based on the feedback law. The method uses the immersed boundary concept in the LBM framework to capture the coupling between a body with complex geometry and a uniform fluid, Then, the flows around a stationary circular cylinder and two circular cylinders in a side by side arrangement are simulated by using the method. Results are agreed well with the benchmark data, so, the capability of the method for complex geometry is demonstrated. Different from the conventional IB-LBM, which uses the Hook＇s law or the direct forcing method to compute the interae- tion force, the method uses the feedback law--the feedback of velocity field and displacement information to calculate the force, thus ensuring the method has advantages of easy implementation and full parallelism.

Quasi-Classical Trajectory Study on O＋＋DH（v=0,j=0）→OD＋＋H Reaction at Different Collision Energy

The quasi-classical trajectory calculations O＋＋DH（v=0,j=0）→OD＋＋H reactions on the RODRIGO potential energy surface have been carried out to study the isotope effect on stereo-dynamics at the collision energies of 1.0, 1.5, 2.0, and 2.5 eV. The distributions of dihedral angle P（~r） and the distributions of P（Or） are discussed. Furthermore, the angular distributions of the product rotational vectors in the form of polar plot in θr and φr are calculated. The differential cross section shows interesting phenomenon that the reaction is dominated by the direct reaction mechanism. Reaction probability and reaction cross section are also calculated. The calculations indicate that the stereo-dynamics properties of the title reactions are sensitive to the collision energy.

Mixed H_2/H_∞ State Feedback Attitude Control of Microsatellite Based on Extended LMI Method

For the appearance of the additive perturbation of controller gain when the controller parameter has minute adjustment at the initial running stage of system,to avoid the adverse effects,this paper investigates the mixed H_2/H_∞ state feedback attitude control problem of microsatellite based on extended LMI method.Firstly,the microsatellite attitude control system is established and transformed into corresponding state space form.Then,without the equivalence restriction of the two Lyapunov variables of H_2 and H∞performance,this paper introduces additional variables to design the mixed H_2/H_∞ control method based on LMI which can also reduce the conservatives.Finally,numerical simulations are analyzed to show that the proposed method can make the satellite stable within 20 s whether there is additive perturbation of the controller gain or not.The comparative analysis of the simulation results between extended LMI method and traditional LMI method also demonstrates the effectiveness and feasibility of the proposed method in this paper.

Static output feedback stabilization for second-order singular systems using model reduction methods

In this paper,the static output feedback stabilization for large-scale unstable second-order singular systems is investigated.First,the upper bound of all unstable eigenvalues of second-order singular systems is derived.Then,by using the argument principle,a computable stability criterion is proposed to check the stability of secondorder singular systems.Furthermore,by applying model reduction methods to original systems,a static output feedback design algorithm for stabilizing second-order singular systems is presented.A simulation example is provided to illustrate the effectiveness of the design algorithm.

Quasi-Classical Trajectory Study of the Chemical Reaction Ca+CH_3I

The Ca＋CH3I→CaI＋CH3 reaction system has been studied with the quasi-classical trajectory method on the extended Lond-Eyring-Polanyi-Sato（LEPS） potential energy surface. At collision energy Ecol=10.78 kJ/mol, the calculated results show that the CaI vibrational population peaks are located at v=2. The calculated cross section decreases slowly with the collision energy increasing. The angle product distributions tend toward backward scattering. The calculated （P2（J^1·K）） values deviate slightly from-0.5 and decrease with increasing collision energy. The Quasiclassical trajectory calculation（QCT） results are in reasonable agreement with experimental data. Moreover, the dynamics of the reaction has been discussed.

Reliability Analysis of Repairable System with Multiple Closed-Loop Feedbacks Based on GO Method

In order to solve the problem of reliability modeling and the analysis of complex systems with multiple closed-loop feedbacks,a new reliability analysis method for repairable systems with multiple closed-loop feedbacks is proposed based on the goal-oriented(GO)methodology.Firstly,the basic theories and advantages of GO method are introduced.Secondly,a type-24B multiple closed-loop feedback structure operator is proposed through GO method with its operation formula given,which expands the types of GO method operators and the application scope of their reliability analysis.Finally,taking a certain type of diesel engine fuel supply system an example,the quantitative and qualitative analysis is carried out through GO method,Monte Carlo simulation as well as FTA respectively.The availability results verify the availability of the proposed type-24B operator in the reliability analysis of multiple closed-loop feedback systems.The qualitative analysis results indicate the accuracy and usability of the GO method as a qualitative analysis method.

A sensitive method of determining optic axis azimuth based on laser feedback

A sensitive method to determine the optic axis azimuth of the birefringence element is presented, which is based on laser feedback. The phase difference between the two intensities in birefringence feedback changes with the angle between the optic axis of the birefringence element and laser original polarization. The phase difference is highly sensitive to the relative position of the optic axis and the laser original polarization. This method is used to highly precisely determine the optic axis azimuth, and is able to distinguish between the fast axis and the slow axis of the birefringence element. Theoretical analysis and experimental results are both demonstrated.

热室气动位置传感器反馈滞后补偿研究

热室辐照环境中的各类型射线会严重影响电子元件的服役寿命,因此目前多采用气动位置传感器来替代,其将感知及信号处理部分分别置于辐照环境和热室绿区来提高传感器的可靠性。由于气体的可压缩性,气动位置传感器存在信号反馈滞后现象。为了改善上述问题,分析了气动位置传感器的流量特性,建立了管道内流场数值模型并采用特征线法进行求解,构建了传感器压力响应预测模型,推导得到滞后量,并基于此提出了补偿策略。最后搭建了气动位置传感器响应检测平台,验证了预测模型及滞后补偿策略的有效性,结果表明:补偿后的位置相对预期值最大差值在0.5 mm以内,能够满足工程应用要求。

公共健康视角下的恢复性环境实证研究综述

社会飞速发展,人类对健康生活的追求给予了环境新的价值和意义,环境的健康效益被深度挖掘。本文利用Citespace可视化分析工具,基于Web of Science数据库的346篇文献和中国知网166篇文献,从环境和需求两个角度梳理恢复性环境基础理论及概念,分类总结研究内容和研究热点,比较分析实证研究中的材料呈现、被试筛选及实验方法。最后,针对研究内容和实验流程进行深入探讨,挖掘恢复性环境研究的新内容,思考有关样本量有效性、前期施压程度及首位效应等实验中的关键问题,以期为后续恢复性环境的实证研究提供有力参考,作为循证设计与实践结合的科学指导。

肾内科教学中采用SHARP反馈法的效果及对教学满意度的影响

目的探析SHARP反馈法在肾内科教学中的应用效果。方法选取2021年5月至2022年5月皖南医学院弋矶山医院肾内科实习生50名,依据随机数表法分为两组,每组各25名。对照组采用传统教学方法,观察组采用SHARP反馈法。比较两组学习成绩、教学质量评分及教学满意度。结果观察组学生学习成绩、教学质量评分包括学习和学术价值、教师的情操、组织和表达、师生关系和互动、教师知识面评分高于对照组,差异有统计学意义(P<0.05),观察组教学满意度、学习能力评分包括学生临床思维、课堂氛围、自学能力、临床实践能力、表达能力及知识关联能力高于对照组,差异有统计学意义(P<0.05)。结论肾内科教学中采用SHARP反馈法教学的效果明显,可提升实习生学习成绩,为实习生提供高质量教学,同时提升实习生对教学方法的满意度,临床教学中可大力推广及应用。

系统动力学反馈环快速计算法研究

针对系统动力学传统枝向量行列式反馈环计算法存在计算时花费时间过长、计算结果容易出错且难以检验等问题,提出了系统动力学反馈环快速计算法。该方法借助Vensim软件Loops功能,以各流位变量为起点生成系统反馈回路集,再删除重复反馈环,可得到此系统所有非重复反馈环集合。以萍乡明鑫农场“基地+农户”供应链复杂系统为例,借助已构建的11棵强简化流率基本入树模型,分别用行列式计算法和该方法计算得出该系统所有反馈环。研究表明,两种方法最终计算结果相同,但反馈环快速计算法却能大大节省计算时间,并提高计算准确率。并可基于此深入分析系统结构,以期提出相对应的管理对策。

创新型建筑类人才思维能力培养研究与实践——以吉林建筑大学城乡规划专业为例

面对城乡规划专业转型,城乡规划专业高校教育改革需要不断更新教育理念、改变教育思维、完善教学内容、创新教育模式。以吉林建筑大学为例,运用SPSS分析、研究、更新教学全过程,让学生具备工程实践能力的同时,培养其研究性思维能力,实现双能型人才的培养目标,向社会输送符合职业需求的专业人才。

线上线下联合教学结合视频反馈教学法在诊断学教学中的应用

目的探讨线上线下联合教学结合视频反馈教学法在诊断学教学中的应用效果。方法选取2022年2—8月中南大学湘雅三医院2019级五年制临床医学专业的136名学生作为研究对象,随机分配68名学生采用线上线下联合教学模式,设为线上线下联合组,其中34名学生进行视频反馈,为线上线下联合视频反馈组;其余不进行视频反馈,为线上线下联合未视频反馈组。另外的68名学生采用传统教学模式,设为传统教学组,其中34名学生进行视频反馈,为传统教学视频反馈组;其余不进行视频反馈,为传统教学未视频反馈组。所有学生由同医院同教师授课,比较各组学生的理论和实践技能考核总成绩。结果线上线下联合组学生的操作成绩[(39.11±7.14)分]和总成绩[(75.67±4.47)分]高于传统教学组学生[(31.58±6.02)分、(67.70±5.87)分],差异有统计学意义(P<0.05)。视频反馈组学生的操作成绩[(36.93±6.30)分]和总成绩[(73.24±4.63)分]均高于未视频反馈组[(33.86±7.16)分、(70.33±6.21)分],差异有统计学意义(P<0.05)。细分各组学生成绩发现,各组学生理论成绩比较,差异无统计学意义(P>0.05);各组之间学生的操作成绩和总成绩比较差异有统计学意义(P<0.05)。线上线下联合视频反馈组学生成绩最好,其次为线上线下联合未视频反馈组,然后为传统教学视频反馈组再次,传统教学未视频反馈组最低。结论线上线下联合教学结合视频反馈教学法能提高学生的物理诊断学成绩,激发学生学习兴趣,提高自主学习能力,具有良好的教学效果。

线上直播联合回馈教学法在孕妇学校中的应用

目的 探讨线上直播联合回馈教学法在孕妇学校中的应用效果。方法 选择2019年1月至2022年8月在该院产检及分娩的584例孕产妇作为研究对象,其中2019年1月至2021年8月产检及分娩的孕产妇(308例)为对照组,2021年9月至2022年8月产检及分娩的孕产妇(276例)为试验组。对照组采用传统孕妇学校模式进行健康教育,试验组采用线上直播联合回馈教学法进行健康教育。分别对2组孕产妇听课情况、课程满意度、健康教育效果及分娩自我效能进行评价对比。结果 试验组孕产妇在听课次数、分娩自我效能、操作类课程满意度方面优于对照组,差异均有统计学意义(P<0.05)。2组孕产妇理论课程满意度比较,差异无统计学意义(P>0.05)。试验组孕产妇健康教育效果相较于对照组有待提高,差异有统计学意义(P<0.05)。结论 线上直播联合回馈教学法能提高孕妇的健康教育参与度及其分娩自我效能,但学习效果及学习满意度仍有待提高。

基于视频回授法的情景模拟教育对2型糖尿病患者自护能力的影响

目的:探讨基于视频回授法的情景模拟教育对2型糖尿病患者自护能力的影响。方法:选取2021年2月1日~2022年2月1日就诊的196例2型糖尿病患者为研究对象,根据抽签法随机分为对照组和观察组各98例,对照组实施常规健康教育模式,观察组实施基于视频回授法的情景模拟教育;比较两组护理前后疾病相关知识知晓、血糖控制情况[包括空腹血糖(FPG)、糖化血红蛋白(HbA 1c)、餐后2 h血糖(2 hPG)]、生活质量[采用世界卫生组织生存质量测定量表简表(WHOQOL-BREF)]及依从性。结果:护理后,两组疾病相关知识知晓情况、FPG、HbA 1c、2 hPG、WHOQOL-BREF评分均优于护理前(P<0.05),且观察组优于对照组(P<0.05);出院前、出院后1个月,观察组依从性高于对照组(P<0.05)。结论:基于视频回授法的情景模拟教育能够提高2型糖尿病患者的自我护理能力,有利于控制血糖,提高糖尿病知识的掌握程度,从而提高患者生活质量和治疗依从性。