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In response to the engineering, miniaturization, and high measurement accuracy requirements of encoders, this paper proposes a new type of absolute photoelectric encoder based on a position-sensitive detector (PSD). It breaks the traditional encoder's code track design and adopts a continuous and transparent code track design, which has the advantages of small volume, high angle measurement accuracy, and easy engineering. The research content of this article mainly includes the design of a new code disk, decoding circuit, linear light source, and calibration method. The experimental results show that the encoder designed in this article has achieved miniaturization, simple installation and adjustment, and easy engineering. The volume of the encoder is Φ50 mm × 30 mm; after calibration, the resolution is better than 18 bits, and the accuracy reaches 5.4″, which further demonstrates the feasibility of the encoder's encoding and decoding scheme. [ABSTRACT FROM AUTHOR]

With the application of encoders in artificial intelligence and aerospace, the demand for the miniaturization and high measurement accuracy of encoders is increasing. To solve this problem, a new absolute matrix encoder is proposed in this paper, which can realize 19-bit matrix coding by engraving two circles of matrix code, and has the advantages of fewer circles of code disk engraving and higher measurement accuracy. This article mainly focuses on the design of a new matrix code disk, encoding and decoding methods, decoding circuit design, Matlab simulation analysis, and experimental error analysis. The experimental results show that the encoder designed in this paper achieves ultra-small volume Φ30 mm × 20 mm, and the angle measurement accuracy is 2.57". [ABSTRACT FROM AUTHOR]

The machining accuracy of the compensation hole of the automobile brake master cylinder directly determines the safety of the automobile and the reliability of parking. How to detect the parameters of the compensation hole with high precision becomes a crucial issue. In this paper, by analyzing the principle of Hough transform detection technology and several optimization algorithms, a new method combining Zernike moment and improved gradient Hough transform is proposed to detect the circular hole parameters. The simulation experiment shows that the proposed algorithm satisfies 0.1 pixels in the coordinate detection of the center position, and the radius detection accuracy is 0.05 pixels, with fast detection speed and good robustness. Compared with the random Hough transform algorithm and the gradient Hough transform algorithm, the algorithm proposed in this paper has higher detection accuracy, faster detection speed, and better robustness, which meets the online detection accuracy requirements of the brake master cylinder compensation hole., Author(s): Changfu Zhao [1]; Hongchang Ding (corresponding author) [2]; Guohua Cao (corresponding author) [2]; Ying Zhang [1] 1. Introduction With the development of society, automobiles are also increasing. The reliability [...]

The compensation hole of the automobile brake master cylinder is an important structural part for adjusting the reservoir and pressure chamber of the brake master cylinder. Its detection accuracy is strictly controlled. However, because the compensation hole is located on the inner wall of the blind hole, the existing detection method cannot meet the testing needs. Therefore, this paper introduces the SSD model into the detection of the compensation hole of the brake master cylinder, and realizes the rapid positioning of the compensation hole by means of network fine-tuning. The compensation hole positioning detection is carried out on the self-developed automobile brake master cylinder compensation hole detector. The entire detection process time is about 5s, and the positioning accuracy is high. We apply the fine-tuning SSD model to the detection of the compensation hole of automobile brake master cylinder, which replaces the traditional method based on human-computer interaction to determine the position of the compensation hole. It has better detection accuracy and faster detection speed, and lays the foundation for the subsequent detection of the size of the compensation hole.

The existing refractors are mainly fixed devices, and require different degrees of cooperation during the refraction process, which takes a long time and is relatively easy for adults, but it is difficult for preschoolers and people with difficulties in cooperation. Optometry. In this paper, by designing a handheld automatic refractor, the composition, working principle and working process of the refractor are introduced. Through benchmarking experiments with the existing traditional refractor, the experiment shows that the accuracy of the diopter detection by the algorithm in this paper is less than 0.05D, and the detection time is about 5s. The speed is fast and the operation is simple, which solves the problem of vision screening for preschool children or those with disabilities.

To improve the speed and position detection accuracy of surface-mount permanent magnet synchronous motor (SPMSM) vector control and reduce unnecessary chattering of the system, this paper proposes a sensorless control strategy of SPMSM based on an adaptive sliding mode observer (ASMO) with optimized phase-locked loop (OPLL) structure. First, in order to overcome the chattering of system caused by discontinuous switching characteristic of signum function in conventional sliding mode observer (CSMO), a continuous saturation function is selected as the switching function. The ASMO adopts the system state-related adaptive gain function to adjust the switching gain value of the system in real time, which overcomes the slow response speed or severe chattering of the system caused by the constant switching gain of CSMO. Second, to reduce the phase delay between the rotor position estimation value and the actual value caused by the adoption of low-pass filter (LPF) and the position estimation error caused by arctangent function method, an OPLL method is designed for accurate estimation of rotor position and speed. Finally, the effectiveness and feasibility of the proposed improved SMO algorithm is verified by simulation and experiments on an SPMSM with rated power of 2 kW. [ABSTRACT FROM AUTHOR]

During the startup process of a centrifugal pump, the vibration and noise problems caused by unsteady flow are the focus of attention, and pressure pulsation is one of the main reasons for this problem. In the current research, a special impeller with blade pressure side trimming was proposed to reduce the strong pressure pulsation phenomenon during the startup process of centrifugal pumps. This article uses numerical simulation methods to simulate three typical blade trailing edges: original trailing edge (OTE), pressure side long linear (LLPS), and pressure side short linear (SLPS), and verifies them with experimental results. The results indicate that although the head of the centrifugal pump after filing has been reduced, its efficiency has been improved to a certain extent. Thirteen monitoring points were set up near the impeller outlet circumference and volute tongue to analyze the changes in pressure pulsation, verifying that blade trimming has a significant inhibitory effect on pressure pulsation during the startup of centrifugal pumps. The average maximum pressure pulsation amplitude of all monitoring points decreased by 32.23%, and the maximum pressure pulsation amplitude decreased by 56%. Blade trimming can affect the internal flow field distribution of centrifugal pumps. By analyzing the static pressure distribution, velocity streamline distribution, and vorticity distribution at the middle interface of three different impellers during startup, it was verified that there is a close relationship between pressure pulsation and unsteady flow structure during startup. The final conclusion is that blade trimming has a significant inhibitory effect on the pressure pulsation of the centrifugal pump during startup, and the impeller outlet vorticity is significantly reduced. The scheme proposed in this study has far-reaching prospects in the design of low noise centrifugal pumps. [ABSTRACT FROM AUTHOR]

Photoelectric encoders are widely used in high-precision measurement fields such as industry and aerospace because of their high precision and reliability. In order to improve the subdivision accuracy of moiré grating signals, a particle swarm optimization compensation model for grating the subdivision error of a photoelectric encoder based on parallel iteration is proposed. In the paper, an adaptive subdivision method of a particle swarm search domain based on the honeycomb structure is proposed, and a raster signal subdivision error compensation model based on the multi-swarm particle swarm optimization algorithm based on parallel iteration is established. The optimization algorithm can effectively improve the convergence speed and system accuracy of traditional particle swarm optimization. Finally, according to the subdivision error compensation algorithm, the subdivision error of the grating system caused by the sinusoidal error in the system is quickly corrected by taking advantage of the high-speed parallel processing of the FPGA pipeline architecture. The design experiment uses a 25-bit photoelectric encoder to verify the subdivision error algorithm. The experimental results show that the actual dynamic subdivision error can be reduced to ½ before compensation, and the static subdivision error can be reduced from 1.264″ to 0.487″ before detection. [ABSTRACT FROM AUTHOR]

In order to analyse the system spatial vibration of compound biaxial and inter-shaft bearings during unbalanced excitation, the theory of rotor dynamics and bearing contact deformation are combined to establish a coupling system model of compound biaxial and inter-shaft bearings. Considering the moment of inertia, gyro effect, and structural damping, a one-dimensional beam model is used to perform the MATLAB numerical calculation of the coupling system to obtain the modal characteristics of the system, and based on the ANSYS simulation analysis of the three-dimensional model, a modal test is used to obtain the system modal shape and test frequency response function to verify the rationality of the coupling system model. Based on the Runge-Kutta iterative method and Hamilton's principle, the nonlinear amplitude-frequency response of the system is calculated while taking into account the influence of the compound biaxial eccentricity, as well as the stiffness and radial clearance of the inter-shaft bearing. The results show that the changes in the eccentricity of the compound biaxial and the structural parameters of the inter-shaft bearing cause the unbalanced excitation of the system, additional external load changes, and different coupled vibrations between the composite compound biaxial and inter-shaft bearings. Therefore, it is reasonable to match the structural parameters of the coupling system and improve the dynamic performance to avoid system resonance. [ABSTRACT FROM AUTHOR]

The 16/6/8 double-stator bearingless switched reluctance motor (DSBSRM) is used as the object of study in this paper. To solve the problem of torque and levitation force ripples in this motor, a control system direct force control (DFC) and direct instantaneous torque control (DITC) based on the torque sharing function (TSF) are proposed. With the strong nonlinearity and approximation capability of radial basis function neural networks, the torque and levitation force observer are designed. The observed torque and levitation forces are used as feedback for the internal loop control, which is combined with the external loop control to make a double closed-loop control. In order to further improve the output torque and system robustness and suppress the torque ripple in steady-state process, the motor winding method is optimized and a set of switching angles is added on the basis of TSF. The simulation results verify the effectiveness and superiority of the proposed control method. It effectively suppresses speed ripple and reduces torque and levitation force fluctuations and rotor radial displacement jitter. [ABSTRACT FROM AUTHOR]

For high-speed permanent magnet synchronous motor (PMSM), its efficiency is significantly affected by the performance of permanent magnets (PMs), and the phenomenon of demagnetization will occur with the increase of PM temperature. So, the temperature detection of PMs in rotor is very necessary for the safe operation of PMSM, and direct detection is difficult due to the rotation of rotor. Based on the relationship between permanent magnet flux linkage and its temperature, in this paper, a new temperature estimation method using model reference fuzzy adaptive control (MRFAC) is proposed to estimate PM temperature. In this method, the model reference adaptive system (MRAS) is built to estimate the permanent magnet flux linkage, and the fuzzy control method is introduced into MRAS, which is used to improve the accuracy and applicable speed range of parameters estimated by MRAS. Different permanent magnet flux linkages are estimated in MRFAC based on the variation of stator resistance, which corresponds to different working temperatures measured by thermal resistance, and the PM temperature will be obtained according to the estimated permanent magnet flux linkage. At last, the back electromotive force (BEMF) is measured on the experimental motor, and the flux linkage and PM temperature of the experimental motor are deduced according to the BEMF. Compared with the experimental results, the estimated PM temperature is very close to the actual test value, and the error is less than 5%, which verifies that the proposed method is suitable for the estimation of PM temperature. [ABSTRACT FROM AUTHOR]

Although the improved strain HR‐5 of Pyropia haitanensis has improvement in yield and quality, it shows earlier maturation and shortened growth period. In this study, blades of HR‐5 strain were treated with 60Co‐γ ray irradiation, and a mutant strain ST‐2 was selected and characterized. The blade length of ST‐2 strain was 401.4 cm on day 70 post‐culture, which was 1.9‐fold longer than that of the parental strain HR‐5. The blades of HR‐5 strain matured earlier and most were matured on day 55, while the ST‐2 strain was not matured until day 90. When blades of HR‐5 and ST‐2 strains were firstly cultured at 23°C for 40 days and their blade discs cultured at 29°C for another 30 days, the mean length of ST‐2 strain was 2.0‐fold longer than that of HR‐5 strain. Besides, the contents of Chl. a and phycobiliprotein and the conchospore numbers in ST‐2 were comparable to that in HR‐5 strain. In summary, compared with HR‐5, we observed delayed maturation, increased length, weight and high‐temperature resistance of the blades, high content of photosynthetic pigments, and high production of conchospores in ST‐2, suggesting it might be a better strain for large‐scale production. [ABSTRACT FROM AUTHOR]

Abstract The blade outlet angle β 2 is one of the key design parameters of the centrifugal pump, which has an important influence on the internal flow field and performance of centrifugal pump. In this paper, five impeller models with different blade outlet angles (23°, 25°, 27°, 29° and 31°) were built by Solidworks and CFturbo under the premise of other impeller parameters unchanged, and numerical simulation of high specific speed (n s = 192) pump was carried out in the commercial code ANSYS-CFX. Then the experiment was performed to test the hydraulic performance of centrifugal pump. The results show that the change trend of numerical simulation and experiment is similar, and when the flow rate increases gradually, the hydraulic loss of impeller becomes larger with the increase of blade outlet angle, and the blade outlet angle has obvious influence on the efficiency of centrifugal pump at high flow rate. Besides that, it has small influence on the head, which changes relatively larger at low flow rate than that at high flow rate. And all the research results could provide appropriate reference for designers to select reasonable outlet angle. Highlights • Five impeller models with different blade outlet angles (23°, 25°, 27°, 29° and 31°) were built by Solidworks and CFturbo. • umerical simulation of high specific speed (n s = 192) pump was carried out in the commercial code ANSYS-CFX. • Experiment was performed to test the hydraulic performance of centrifugal pump. • The results show that the change trend of numerical simulation and experiment is similar. • All the research results could provide appropriate reference for designers to select reasonable outlet angle. [ABSTRACT FROM AUTHOR]

This paper is concerned with the modal analysis of a thick-disk rotor, which consists of an elastic shaft with a rigid thick disk assembled by interference fit, and the width of the thick disk is not negligible. Firstly, the friction moment on the contact surface of disk and shaft is deduced in terms of elastic theory, and a new enhanced coefficient of bending stiffness of assembly body is proposed and calculated for the first time. Secondly, the effect of the width of thick disk on diametrical moment of inertia, as well as the enhanced coefficient of bending stiffness of interference-fit part between disk and shaft, is included in the motion equations of thick-disk rotor, which are established based on finite element method, and the natural frequencies of rotor are obtained by solving the motion equations. Then the modal analysis is performed to get the natural frequencies in ANSYS Workbench, in which the friction coefficient and interference fit are set to be the same as those of the finite element calculation method. At last the modal experiment is done to verify the accuracy of calculation and simulation. The results show that the calculation values using enhanced stiffness of assembly part are in good agreement with those of ANSYS Workbench and experiment, and the percent errors of the first natural frequency and the second natural frequency are down to about 0.32% and 0.83%, respectively. [ABSTRACT FROM AUTHOR]

As a precision position sensor, the photoelectric encoder has difficulty avoiding eccentricity or tilt error in the industrial manufacturing and assembly process. At present, manual error correction is often used to adjust. The adjustment efficiency is low, and it has difficulty cooperating with other types of error compensation methods. In view of these problems, we proposed a photoelectric encoder eccentricity error detection and compensation method based on digital signal bandpass filtering that effectively corrects the signal deviation caused by the installation eccentricity in the output signal and judges the direction and magnitude of the eccentricity error to realize the encoding correction of eccentricity and inclination error of the device. The mathematical model of the eccentric error generation principle of the photoelectric encoder combined with the Lissajous figure was derived. We then demonstrated the design of a photoelectric encoder error detection platform to detect photoelectric encoders of different diameters in real time. Finally, using the advantages of field programmable gate array high-speed parallel processing, the error compensation algorithm was written into the development chip to improve the efficiency of processing the encoder output error signal. This method can adapt to the eccentricity error correction and compensation of different models of photoelectric encoders and can greatly improve the efficiency and accuracy compared with previous detection methods. [ABSTRACT FROM AUTHOR]

A high-precision error measurement method of angular displacements based on the biaxial of the reciprocal roll angles (RRA) is presented. The resolution and precision of the angular displacement measurement systems are guaranteed using the principle of small-angle measurements, along with a photoelectric autocollimator and reflector. Based on the method of the biaxial RRA and the principle of full-circle closure, a displacement measurement system covering the full circumferential range is built. The displacement measurement system can recognize the reference angle error elimination, the calibration angle error, and mutual compensation. The total error model of the angular displacement error measurement and the biaxial turntable is established, and the main error terms are analyzed using the total error model of the turntable and the components. The traditional "Fourier harmonic analysis" and sparse decomposition methods are used to correct the system error components. The simulation accuracy of the corrected turntable is similar to that of the error-free term, and the analysis results are used in the system-optimized configuration, including precision distribution. The experiment verifies the feasibility and effectiveness of the proposed high precision, angular displacement, and error measurement method. [ABSTRACT FROM AUTHOR]

This paper takes centrifugal fan as the research object and establishes five impeller models with different blade outlet angles. By means of computational fluid dynamics (CFD), the external characteristics of the centrifugal fan and the internal characteristics, including the velocity, pressure, and turbulent energy distribution, at the middle span plane of the impeller or fan were obtained and compared. In addition, the pressure fluctuations surrounding the impeller outlet were also analyzed. The results showed that the change of the blade outlet angle of the centrifugal fan had a great influence on the performance; the total pressure and efficiency of the fan were the highest when the outlet angle of the blade was increased to 29.5° under the design flow rate; and the influence of the outlet angle on the fan performance was different in off-design conditions. On the other hand, at different flow rates, the change of the internal flow field with the increase of the outlet angle was different. For the pressure fluctuation of the fan, by increasing the blade outlet angle properly under high flow conditions, the fluctuation amplitude of the fan at the blade frequency and its frequency multiplication could be reduced, which is conducive to decreasing the impeller noise. The research results have good guiding significance regarding the design of the pneumatic performance and noise reduction performance of centrifugal fans. [ABSTRACT FROM AUTHOR]

• A crossing experiment of Pyropia yezoensis was carried to select an improved strain. • The characteristics of improved strain were evaluated from the aspects of yield, quality, stress resistance and released number of conchospores. • A-13 strain which was fast growth, high-temperature resistance, high quality; large amount of conchospores as well as wild like color was selected. A crossing experiment between the green mutant (C-0 , ♀) and red mutant (fre , ♂) of Pyropia yezoensis was carried out for breeding an improved strain which was fast growing, high quality and wild type color, finally an improved strain (A-13) was isolated from the F 1 gametophytic blades. The mean length and length-width ratio of the 60-day-old blades in A-13 were 73.43 cm and 35.41, which were 1.69 and 2.92 times higher than those of the wild-type strain (WT) of P. yezoensis , respectively, and the wet weight had no significant difference between the two strains. After being cultured for 60 days, the contents of chlorophyll a and phycobiliprotein of A-13 were 10.35 and 79.77 mg/g, which were 1.93 and 1.63 times higher than those of the WT strain, respectively. The thickness of the 60-day-old blades of A-13 strain was 19.86 μm, which was 30 % thinner than that of WT strain. In addition, the total number of conchospores per shell released from A-13 was 1408.83 × 104, which was 2.45 times higher than that of WT strain. The above results confirmed that A-13 strain was characterized by fast growth, high quality; large amount of conchospores as well as wild like color, therefore, A-13 is expected to be applied in commercial cultivation. [ABSTRACT FROM AUTHOR]

A high specific speed centrifugal pump is used in the situation of large flow and low head. Centrifugal pump parameters need to be optimized in order to raise its head and efficiency under off-design conditions. In this study, the orthogonal experiment design method is adopted to optimize the performance of centrifugal pump basing on three parameters, namely, blade outlet width b2, blade outlet angle β2 and blade wrap angle φ. First, the three-dimensional model of the centrifugal pump is established by CFturbo and SolidWorks. Then nine different schemes are designed by using orthogonal table, and numerical simulation is carried out in CFX15.0. The final optimized combination of parameters is b2 = 24 mm, β2 = 24°, φ = 112°. Under the design condition, the head and efficiency of the optimized centrifugal pump are appropriately improved, the increments of which are 0.74 m and 0.48%, respectively. However, the efficiency considerably increases at high flow rates, with an increase of 6.9% at 1.5 Qd. The anti-cavitation performance of the optimized centrifugal pump is also better than the original pump. The results in this paper can provide references for parameter selection (b2, β2, φ) in the centrifugal pump design. [ABSTRACT FROM AUTHOR]

In order to realize the automatic quality measurement of laser welding parts, an automatic on-line quality measurement system is established. The optical coherence tomography algorithm used in the system is studied. Firstly, the test equipment of laser welding quality inspection system is built based on optical coherence tomography algorithm. Then, the typical control algorithm is analyzed by taking the scanning galvanometer control as an example, that is, high-precision scanning and high-precision image acquisition in X and Y directions are realized. Then, the image is processed by dual-tree complex wavelet transform. Finally, the test sample is tested with the test equipment and the test results are analyzed. Experimental results show that this method can detect the quality of laser welding seam, and the detection accuracy is 5 µm. It provides industrial solutions for the online inspection of the laser welding to enable consistent and high quality welds. [ABSTRACT FROM AUTHOR]