Diffraction and grating are important contents of basic optical courses and optical experimentsplaying an important role and application in traditional optical technology and frontier scientific research.Byusing the spatial light modulator( SLM) , the experiment of fractional optical vortex based on the diffractioneffect of the fork grating is designed and caried out.The fork grating holograms are calculated by the computerprogram and loaded onto the SLM. The fractional optical vortex is generated and observed experimentally , and the characteristics and intensity distribution of which are also analyzed.Through this experiment ,students havefurther deepened their understanding of difraction and grating characteristics, stimulated their interest infrontier optical research and exploration, expanded their professional knowledge , and enhanced their innovativeawareness on optical research and control of light field.

AC amplification circuit is an important type of circuit in electronic engineering, and its basicstructure and parameters have a significant impact on its performance.However, due to the coupling ofcomponent parameters and discontinuity issues in the design of AC amplification circuits,it is difficult toachieve the optimal performance target of the circuit.Therefore , this article presents a parameter optimizationmethod for AC amplification circuits based on Lagrange multipliers.Firstly ,the transfer function equation of theamplification circuit is derived using Kirchhoff's law.Then ,the main parameters of the AC amplifier,includingcenter frequency and amplification factor, are discussed, and finally, the quality factor is derived.Using theLagrange function, the maximum value of the quality factor is obtained under given center frequency andamplification factor,by treating them as constraints and solving for the maximum value of the function underthese two complete constraints.Based on a typical AC amplification circuit system, it explains the parameteroptimization method based on Lagrange multipliers, which provides a theoretical basis for the optimizationdesign of AC amplification circuits.

lt studies the effect of pull-off velocity on the accuracy of water surface tension coefficientmeasurement. The result shows that the measured surface tension coefficient of water will be smaller when alarger pull-off velocity is applied. lt leads to greater experimental error. The relatively slow pull-off speed isconducive to improving the measurement accuracy of the experiment. At the same time, COMSOL simulationmethod is used to analyze the morphology of water film before and after pull-off. lt is discussed of the relationship between different pull-off speed and the morphology of water film. And then, a reasonableexplanation is given to the experimental results. lt provides an experimental basis for accurately measuring the surface tension coefficient of water.

The expression of the light field distribution in the image plane of the converged-spherical waveincident two-dimensional amplitude grating in Fresnel diffraction region was derived by using the Fouriertransform and Fresnel-Kirchhoff diffraction theory. And the imaging conditions as well as the imaging law areanalyzed. The Talbot effect is observed by experiment,and the average error between the measured data and theheoretical value is about 4.6% which verifies the correctness of the derived formula. The results of the study improve the theory related to the Talbot effect and have certain reference value for its application expansion.

An experimental device for measuring optical activity and concentration of glucose and sucrosesolutions was designed based on the PASCO platform.The experimental optical path layout could be observedthrough discrete devices such as laser, polarizer and light intensity sensor, which helped students to deepentheir understanding of the principle of optical activity solution measurement.By connecting the rotation sensorand light intensity sensor to the computer, the optical rotation and light intensity extremes can be accuratelyocated and the measured values can be read ,avoiding the possible position imprecision and reading deviationcaused by manual operation.Compared with the measurement of gyroscope, the results show that the discretedevice using PASCO platform can effectively reduce the error.On this basis,the experimental device can beextended to real-time on-line measurement and monitoring of flowing optically active liquid concentration.

Aiming at the two problems existing in the college physics experiment courses ; the experimentacontent is out of touch with cutting-edge technology and the lack of innovative thinking training. The physics experiment center of Harbin Institute of Technology ( Shenzhen ) took the connection between opticalexperiments and fiber-optic communication technology as the starting point ,improved the teaching method byenriching the course content,improving the assessment method ,combining competition and scientific research. etc., and achieved good results. The students’ learning enthusiasm and initiative have been greatly improved. their innovative thinking ability has been significantly enhanced, and they have achieved excellent results in thecompetitions.

The soap film filter was realized by constructing planar soap film and positively curved soap film.The phase diagram and high-speed camera system were combined to study the filtration of soap film and thedynamic process of glass particles penetrating soap films.n the phase diagram constructed by the the fallingheight of glass particle and the diameter of circular soap film , the load-bearing mass of soap film decresedgradually with the increasing diameter of glass particle and the maximum load-bearing mass of soap film alsoprecipitously dropped. When the falling height of glass particle and the diameter of the soap film remainedconstant,the decrease in the load-bearing mass was mainly due to the increase in the diameter of the glassparticle.During the dynamic process of glass particle penetrating soap film , soap film firstly took on funne:shaped deformation and contracted at the neck during the process of glass particle penetrating the soap film ,and then ruptured from the glass particles as a satellite bubble. With the increasing Weber number, the soapfilm deformed severely and were more prone to rupture when the Weber number exceeding 9000.

Fano resonance has been widely used in hot fields such as nano-metamaterial.Through a simpleharmonic oscillator model, the dynamics mechanism of Fano resonance was deduced in detail, and theresonance system of double-coupling harmonic oscillator was designed. The concept of Fano resonance was firstintroduced into the university physics experiment teaching system.  We also provides detailed experimentaldesign and application scheme ,which is an effective supplement to the concept of resonance in the universityphysics experimental teaching system ,  and also enhances the frontier and comprehensiveness of experimenta courses.

College physics experimental projects cover a wide range, which based on rigorous theory andexperimental means.This course provides students with basic experimental skills training,which is an importantmeans to cultivate studentsscientific thinking and improve their scientific literacy.However, there are someproblems such as lack of innovation and lack of integration with life in university physics experiment course.Inthis experiment,thermistor is used to replace the fixed value resistance as the research object,and Wheatstone bridge is used as the carrier to study the relationship between the resistance value and temperature of NTC typethermistor at different temperatures.By fitting the variable relation between temperature and resistance value.the function relation of resistance value changing with temperature is obtained. And then ,the resistance value atany temperature can be obtained.Since thermistors can be seen everywhere in daily life , students’ interest inlearning can be enhanced.This operation can improve the expansion of basic physics experiment,and improvestudents’ practical ability and innovation ability. So students can understand the resistance temperature characteristics of negative temperature thermistor while mastering the working principle of Wheatstone bridge

Using the properties that electrorheological fluid can form periodic chain structure under the electricfield,we have made electrorheological fluid grating experimentally. We set up a liquid grating device withconcentrated giant electrorheological fluid illuminated by an uniform laser beam with small spot. Under theaction of electric field, we observed the standard optical grating diffraction phenomenon. Furthermore, wemeasured the experimental data such as grating constant and diffraction fringe spacing, and we summarized theexperimental data.To verify the physics in fluid grating,we compared traditional grating with liquid grating bymeasuring the grating constant for the same diffraction fringes , the error analysis shows that the fluid gratingdata fit very well.

Innovative experimental teaching based on research guidance has attracted more and more attentionin the open experimental teaching of undergraduates. lt takes the research on electrochromic properties oltitanium dioxide thin film as an example to integrate the cutting-edge hot spots into the exploratorrexperimental teaching of undergraduates, in order to learn the preparation method of titanium dioxide thin filmand study its electrochromic mechanism.Through the method of open teaching practice ,it can guide students independent initiative and exploration in experiments , broaden the channels for students to acquire scientificxnowledge , and cultivate the exploration ability and scientific research thinking.

The modified Michelson interferometer is used to measure the refractive index of sucrose solution. The device uses the OpenM camera to identify the interference fringes ,the gear motor and the stepper motorto measure the displacement ,and the Arduino microcontroller to control and calculate.The modified Michelsoninterferometer effectively alleviates the visual fatigue in the operation process and reduces the error. Therefractive index measured by experiments accurate and consistent with the theoretical results. Therefore , thedevice can be widely used in college physics experiments, and also provides potential for further industrialapplications.

Liquid refractive index is one of the important optical parameters ,and the measurements of whichare significant in the fields of food production identification ,optical processing,etc. A rotating fine tuning stageis installed on the optical shock absorption platform based on a portable Michelson interferometer.The formulafor calculating the refractive index of the liquid is obtained by considering the changes in the optical pathdifference between the container wall, the measured liquid , and the air after rotation. Compared with the valuesby the Abbe refractometer,  the experimental results show that the average relative errors of water, glucosesolutions of different concentrations , and sodium chloride solutions of different concentrations are respectively1.1%,3.3% and 2.0%, with a maximum error of 5.9%.lt provides a feasible method for measuring therefractive index of liquids,and it can also be used as an expanded experiment for Michelson interferometer, which is of great significance for cultivating undergraduate students’ innovative ability.

Starting from the difficulties in the design and debugging of series switch regulated power supplies.the main reasons are analyzed to be the relatively complex circuit structure, students’ lack of thoroughunderstanding of circuit principles, and lack of experience in complex circuit debugging.In response to thisissue, a gradient progressive debugging scheme was developed using methods such as module decompositionand alternative solutions, which improved the design completion.The complete debugging process was simulatedand demonstrated using the Multisim software , demonstrating effective methods for circuit debugging and fault troubles hooting, which enriched practical guidance cases for switching power supplies.

PASCO rotary motion sensor can accurately measure and record the angular velocity of the objectwhen it rotates in real time.ln the experiment of measuring moment of inertia of rigid body by the falling bodymethod ,in order to improve the accuracy of the experiment , the PASCO rotary motion sensor is used to directlmeasure the angular velocity and calculate the angular acceleration.The improved instrument simplifies theexperimental steps and improves the experimental accuracy. The relative errors of the three groups ofexperiments are 0.2%,0.7% and 0.3% respectively.The experimental results are accurate.  According to theexperimental results,the improved instrument is easy to operate and has higher measurement accuracy.

Based on the Wheatstone bridge , the virtual simulation experiment platform of “ hermistormeasurement"was successfully built by using labVIEW.The thermistor with a negative temperature coeficientis selected as the research object, and the platform realizes the continuous adjustment of two important parameters , A value and B value.During the virtual simulation process , the user measures the correspondingthermistor resistance by changing the experimental temperature , and records it in the “ data acquisition andanalysis odule in real-time. Subsequently, the simulation platform can automatically perform fitting of theexperimental data ,directly display the temperature curve of the thermistor in real-time , give the specific valuesof its slope and intercept, and finally, calculate the A value and B value.The results of multiple simulationsshow that the relative error of the measured thermistor A value and B value is below 1.0% , which has highaccuracy.The virtual simulation experiment has successfully realized all the functions of “ thermistor measurement in the laboratory" and possesses a good visualization effect.lts design ideas can be applied to theconstruction of other experiment virtual simulation platforms.

The horizontal swing of the flat plate hanged by two lines with equal length is a complex problem.We studied the small angular swing of the flat plate in horizontal direction, which belongs to harmonicvibration.Second,the swing frequency of the flat plate is measured by smartphone installed “ phyphox”softwareand its light sensor.We changed the mass of the iron ball placed in the center of the plate and measured itsswing cycle of the system.The measured data were obtainde and the period curves are plotted by Origin softwareto calculate the swing period of i.lt is found that the experimental results are in good agreement with thetheoretical ones.This work provides an experimental surport for dealing with the oscillations of complex systems

District metered area( DMA) technology and leakage control are important means for water supplyenterprises to reduce the operating costs of water supply networks.DMA partition optimization technology has tosome extent simplified the number of sensor configurations , but research on leak localization methods underextremely simple sensor configuration conditions in DMA is still relatively rare.At the same time , the existingresearch results are rare in the analysis of Confounding of leakage location methods. Therefore , based onsimulation experiments the above two issues of leakage localization are studied. Firstly ,introduce the concept ofwater supply network leakage and the application of DMA technology in water supply networks.Then ,based onthe Netl.inp file included in EPANET Matlab Toolkit 2.1.1,a single inlet node was used to configure waterpressure and flow sensors on the EPANET simulation software platform to simulate independent metering zonesunder limited resource conditions.Next ,run EPANET simulation software to simulate the 24-hour water supplsituation in the independent metering area under ideal conditions and a temporary increase in water demand ata certain water supply node ,and obtain two datasets for the inlet nodes.Finally,a BP neural network predictionmodel program was developed using the MATLAB platform, and the two datasets were trained and tested separately. The results show that under ideal conditions, the BP neural network prediction model has highaccuracy in DMA leakage localization under limited resource conditions ,and the temporary increase in water demand at water supply nodes will increase the model prediction error.

In order to get better understand of the electrostatic field, the software , named “ electrostatic fieldexperiments simulation softwareis calculated with finite difference method and design a user interface withMatlab App Designer. The software has description of five electrostatic fields which are “ coaxial cable"parallel wire electrode electric field", “ focusing electrodes" , “ wedge-stripe electrodes” and “ the parallelplate electrode". The software can provide measure the equipotential points ,description of equipotential lineand electrical potential lines and the simulations are completed with the software. The software can helpstudents to establish a more visual and intuitive understanding of electrostatic fields. Students can also comparethe experimental results with the simulation results provided by the software.

Aiming at the requirements of environmental monitoring, energy-saving and safety protection oflaboratory environment, an intelligent monitoring and control system is designed and developed, takingSTC12C5A60S2 single chip microcomputer as the core control unit.The number of people in the laboratory arecounted through the combination of infrared pyroelectric and ultrasonic sensor. Meanwhile , the temperaturehumidity and combustible gas concentration in the laboratory are monitored and displayed in real time. The system can be set to operate in working mode or protection mode.ln working mode , the light on and off andoutput the part of power are controlled according to whether the number of people in the laboratory is zero. Inthe protection mode if the number of people in the laboratory is not zero ,the system will send a message to theadministrator through the SlM module.In both modes ,the system can start sound and message alarm when thecombustible gas exceeds the standard. The system has the advantages of simple structure ,high performance andconvenient operation. lt can be used for the monitoring and protection of laboratories.

LabVIEW is a powerful virtual instrument development platform. It intruduces the programtechnology and usage method of simulation experiment for Wheatstone bridge based on LabVIEW. Virtualexperiment can effectivelysupplement and improve hardware experiment, achieve experimental teachingobjectives similar to actualinstruments.

It mainly focuses on the reform and research of the teaching content and methods of laserprinciples ,and puts forward the “ teaching method of laser principles in English led by introducing cross-scientific research information". Through adding information cross interaction , it is possible to fully mobilize students’ learning enthusiasm,and establish interactive teaching modeSo as to enhance the teaching level ofteachers ,stimulate students’interest in learning ,and significantly enhance students’problem-solving ability inengineering practice.

Physics demonstration experiments play a critical role in enhancing students’ understanding ofphysical theory ,reinforcing knowledge retention , and stimulating scientific curiosity.The majority of universitiesin China have established their own physics demonstration laboratories.Currently, China University of Miningand Technology(CUMT )has three physics demonstration experiment halls with over 120 differentdemonstration instruments.We explore CUMT's methods for effectively utilizing these physics demonstrationexperiment resources.For instance, we suggest normalizing physics demonstration experiments in theoreticaclassrooms ,introducing networked resources , allowing college students to participate in the development andexploration of physics demonstration experimental instruments , opening physics demonstration laboratories tothe public , and more. Furthermore, we analyze the issues and difficulties faced in the pursuit of effectiveutilization of physics demonstration experiments and provide potential solutions to such challenges.The insightsdiscussed can help maximize the value of demonstration experiments in assisting theoretical teaching, fostering students’ innovative skills and promoting scientific curiosity. lt also serves as a reference for colleges anduniversities interested in establishing their physics demonstration experiments.

According to the goals of higher education , comprehensively improve the scientific research qualityof students.Facing the major of optoelectronic information engineering ,the author introduces a set of structuraloptical non-reciprocal experimental schemes based on the cultivation of scientific research and innovationcapabilities. This experiment combines theory and experiment, and introduces the principle of diving deeplyhrough the experiment students not only became familiar with the functions and use of optical instrument sout also exercised their data processing capabilities. Combining theory with experiment not only consolidates thexnowledge points of the classroom , but also cultivates students’ hands-on ability in scientific research.

College Physics is an important public compulsory course for students majoring in science andengineering.ln order to meet the needs of training high-level applied talents, this course focuses on the painpoints in teaching, adhering to the concept of student development as the center,and carries out the reform otwisdom teaching mode.The results show that the intelligent teaching mode has obvious effects on improvingstudents’cognitive participation and knowledge generation , cultivating students’learning ability ,and realizingthe function of ideological and political education in the curriculum. lt provides a useful reference for solvingmany common problems in the teaching of other courses, and also provides a demonstration for the teachingreform of other courses.

The mechanical properties of materials are the core foundational courses in the field of materialforming and control engineering,with the aim of mastering the basic mechanical properties of materials ,testingmethods,and analyzing micro mechanisms , in order to better apply them to practical applications. With thedevelopment of higher education teaching reform in our country ,the traditional teaching mode has been unableto meet the needs of the times , so it is necessary to innovate its teaching methods and methods. Under theconsideration of engineering professional certification standard, the teaching reform of material mechanicalperformance course is carried out in depth ,the actual needs of course teaching under engineering professionalcertification are discussed, corresponding reform standards are formulated ,and the thought of course reform withengineering professional certification as the background is put forward, which provides more effective methodsand ways for teaching reform of material mechanical performance course.

The university physics experiment course plays an important role in cultivating students’ practicaability and comprehensive quality of combining theory with practice.ln view of the problems existing in thetraditional university physics experiment course at the present stage , based on the concept of OBE education.we put forward the reform exploration of teaching activities of “ student-centered and results-oriented”.Thewhole teaching activity emphasizes students’ independent inquiry learning, so as to cultivate students' comprehensive practice and innovation ability. Through practice ,good teaching effect has been achieved, whichhas laid a foundation for improving students’ability of sustainable learning practice in the society.