Abstract:To realize the requirement of refined detection and compensation of fundamental and arbitrary harmonics in complex power grid environment, a new multi-functional refined detection method for fundamental and arbitrary harmonics is designed based on the traditional ip-iq detection method. Based on the instantaneous reactive power theory, the definition of the active/reactive component of harmonic current is given. The frequency signals of the specified harmonics are obtained by using a single phase-locked loop combined with frequency multiplier. The Park transform matrix of the traditional ip-iq method is improved by using the phase synthesis compensation method, and the DC component integral extraction method is designed to replace the low-pass filter in the traditional method. This method makes up for the lack of functionality of traditional detection methods, and has higher detection speed and accuracy. The effectiveness and flexibility of the proposed method are verified by MATLAB/Simulink simulation.

Abstract:The PCB handwriting board sensor is introduced in this paper. With the model of PCB handwriting board, the numerical simulations of the electric fields are conducted and the driving modes fitting for weak signal detection are optimized using the results of the simulations. And then, the driving source and weak signal detection system based on the principle of phase-locked amplifier are designed and realized, which focus on the design principles and methods of AC current source, narrow band pass filter, high gain low noise amplifier, dual phase lock-in amplifier, etc. The method of equipotential line intersection with linear interpolation is presented and verified experimentally. The simulation and experimental results show that the designed system can realize the location of the contact point with the PCB printed board.

Abstract:Aiming at the problem of unclear inter-electrode distance for different depth muscles sEMG signal detection, the effect of inter-electrode distance and muscle fiber depth on sEMG signal in single-fiber sEMG signal simulation model was analyzed firstly in this paper. Then, the relationship between the inter-electrode distance and the amplitude and frequency spectrum of the sEMG signal was analyzed by combining with the sEMG signal acquisition experiment of the extensor carpi ulnaris and diaphragm muscles. The contribution rate of the increase of inter-electrode distance to the increase of sEMG signal amplitude was calculated, and the inter-electrode distance suitable for different muscle levels of sEMG signal detection was determined. Simulation analysis and experimental results show that the increase of inter-electrode can increase the sEMG signal amplitude, and the inter-electrode distance of deeper muscle sEMG signal detection is larger than that of superficial muscle.

Abstract:A rehabilitation treatment without drug based on EEG biofeedback technology was proposed to rehabilitate insomnia patients. The EEG acquisition device is designed based on ADS1299, using QT and MATLAB to compile the EEG signal. The α wave characteristic signal decomposed by wavelet transform is used to represent the brain state, which is fed back to the patients through audio and video. According to the quantitative indicators corresponding to the rehabilitation scheme, make insomnia patients obtain a calm and relaxed state to achieve the purpose of insomnia treatment and rehabilitation. Pittsburgh sleep quality index was used to verify the effect of insomnia rehabilitation instrument on insomnia patients. The test shows this device has no side effects and is effective for insomnia patients.

Abstract:In this paper, a microstrip patch antenna fed by a stripline probe is proposed. The antenna works in X-band, and the patch is square in shape with a width of 9.3 mm; the feeder is bent through the microstrip line to stripline structure, and the upper part forms an L-shaped probe structure. The bandwidth of VSWR ＜ 2 in X-band is about 16.30%, the gain in vertical direction is about 8.78dB, and the cross polarization ratio is about 33.20dB. On the basis of this antenna, a PIFA antenna with similar structure is designed. The antenna bandwidth is increased to 19.1%, and the vertical cross polarization ratio of the patch is about 45.3dB, which is increased by more than 10dB. In practical application, this kind of antenna is not easy to be interfered by other antennas because of its good polarization isolation.

Abstract:The beam steering system is an important subsystem for phased array antennas. The functions of phased array antennas such as beam steering,agility and shaping are accomplished by beam steering system. In traditional way, beam steering system are composed by beam steering crate and units. In order to achieve a high-integrated, high-speed and simplify cable layout system suiting airborne phased array radar, a beam steering system based on Serializer/Deserializer (SerDes) is presented on this article. The modules of system are integrated in antenna to reduce the weight and volume using 2Gbps SerDes as the transmit bus which can simplify the cable connection. The design of system and modules, timing synchronization and high-speed data link are analyzed. The typical performance of the antenna is tested, which validates the design idea.

Abstract:In order to solve the problem that the positioning system of subway relies heavily on the ground transponder, a using two-dimensional codes positioning method is proposed. Based on the high precision clock synchronization, a new data fusion algorithm was designed, the data demodulation circuit was fabricated, a high availability system with symmetric three backups was constructed, and the test method was verified. The experimental results show that the system can realize the autonomous positioning, start and stop of the train with the help of QR code, and display the train status in real time. The positioning accuracy can reach up to cm, and there is no need for the subsequent manual maintenance of the ground transponder, which saves a lot of costs. At the same time, it provides a reliable solution for the test of automatic train driving.

Abstract:Stereo image line feature extraction technology has also been rapid development, for the current line extraction technology review article is relatively small, and line feature extraction research methods are many, various methods are uneven, most researchers are difficult to have a more comprehensive grasp of the situation. In this paper, the line extraction technology of stereo image proposed by scholars at home and abroad is systematically summarized. And this paper summarizes and compares the integrity, anti noise, efficiency and complexity of line feature extraction through experiments. The results show that the improved line feature extraction algorithm can effectively weaken or remove the influence of sawtooth effect in the process of line extraction, so as to quickly obtain line features that meet the requirements of line matching. Therefore, as the basis of stereo matching advanced processing, line feature has great potential in image processing and pattern recognition.

Abstract:In the brushless DC motor (BLDC) drive circuit, a bootstrap capacitance calculation method based on energy conservation is proposed to solve the problem that the gate drive voltage of power field effect transistor (MOSFET) fluctuates greatly. According to the BLDC dynamics model, the single commutation time interval in the six-step commutation is analyzed. The equivalent circuit of BLDC and MOSFET is used to construct the motor drive circuit model, and the energy transfer direction in the circuit is analyzed to calculate the bootstrapping capacitance value. According to the method proposed in this paper, a brushless DC motor drive system is built, and the peak valley difference of the grid driving voltage of the circuit is 0.2V. The experimental results show that, compared with the traditional empirical method, the capacitance selected by this method can improve the grid driving voltage stability by 80%.

Abstract:Zinc sulfide (ZnS) is a kind of widely used optical thin film material, because of its wide light transmission area and easy deposition, it is widely used to make wide spectrum thin film devices. In this paper, terahertz time domain spectroscopy (THz TDS) is used to detect the terahertz spectral characteristics of zinc sulfide. Through experimental analysis and calculation of optical parameters, it is obtained that the transmittance of zinc sulfide in the 0.2-2.4 THz frequency band increases with the increase of frequency, and the refractive index is between 2.88-2.94; from the absorption spectrum, ZnS is There are absorption peaks at 0.23、0.39、0.81and 2.2 THz; and the real part of the dielectric constant is between 8.3-8.7, and the imaginary part is between 0-0.08. This research provides a reference for the application of zinc sulfide materials in the terahertz frequency range.

Abstract:Aiming at the problems of limited purification range, fixed structure, the need to match various indoor cleaning equipment (such as sweeping robot) and high space and economic cost of the existing air purifier, an integrated multi-functional air purifier was designed and developed. In traditional sweeping robot by MCU and air purification part, on the basis of serial communication using various sensors to collect environmental data terminal node, the coordinator node after the analysis of the data processing, single chip microcomputer to working mode to make smart choices, enhance the ductility of the product function, the realization of the innovation the location tracking and purification of sudden pollution sources; Cooperate with the self-developed APP interactive end to improve the user experience; Unique air outlet design effectively solves the problem of weak air convection in small air purifier.

Abstract:Aiming at the problem that the iris collection equipment is expensive and the image quality is poor and the iris positioning is difficult due to the iris collection based on visible light is susceptible to uneven illumination, light spots, specular reflection, eyelash occlusion, etc. A system for collecting iris images based on visible light and evaluating quality and iris positioning is designed. The system takes Raspberry Pi 3B+(RPi 3B+) as the core and drives the IMX477R image sensor to collect multiple eye images.First, the MSRCR algorithm is used to enhance the contrast of the image and the Lagrangian interpolation method is used to remove the effect of the light spot.Second, the Tenegrad function is used to evaluate the image sharpness quality.Finally,the inner edge of the iris was positioned by the gray characteristic thresholded and Daugman circular gradient algorithm, and the outer edge of the iris was positioned by the small area search method and hybrid geodesic area curve evolution method. The test results show that the iris acquisition system is stable and cost-effective, the image quality evaluation pass rate reaches 84% and the iris positioning accuracy rate reaches 91%.

Abstract:Ant colony algorithm plays an important role when intelligent underwater robots carry out path planning in areas such as ocean development, underwater operation, submarine exploration, submarine rescue and life assistance. Because the ant colony algorithm has a certain randomness, together with the large number of ant colonys, it is not only slow to find the optimal solution of the algorithm, but also has interference with problems such as local optimal solutions. In this paper, a co-evolution algorithm is proposed to optimize the three-dimensional path planning problem of the underwater vehicle.By comparing the ant colony algorithm with the particle swarm algorithm and the ant colony algorithm of dynamic pheromone, the efficiency and stability of the algorithm are improved, and the population can select a better path faster to reach the target node.

Abstract:In order to solve the problem of lack of correlation analysis between the components of uncertainty when the air pressure sensor of automatic weather station used GUM to evaluate the uncertainty in the past.This paper takes PTB210 digital air pressure sensor as the research object, designs the corresponding laboratory calibration scheme according to the verification regulation of air pressure sensor, and calculates its corresponding measurement model.On the premise of analyzing the correlation between its uncertainty components, the corresponding uncertainty evaluation method is developed.By implementing this method, the combined standard uncertainty of forward stroke and reverse stroke is 0.065hPa and 0.069hPa respectively at 1010hPa calibration point.This method is more close to the reality, and the result of uncertainty evaluation is more real and reliable, which can effectively make up for the shortcomings of GUM in evaluating the uncertainty of air pressure sensor in the past.

Abstract:In order to reduce the total time of reader identification in RFID system, a new packet DFSA algorithm is proposed to reduce the intra group efficiency of packet DFSA algorithm. The reader sets a dynamic grouping factor by analyzing the recognition results in each frame, the tag generates its own characteristic value according to the chaos pseudo-random number, and then compares it with the grouping factor value to select whether to respond at the current frame. Matlab simulation shows that the system efficiency of the new algorithm is stable and the number of time slots needed for identification is reduced. When the number of tags to be identified is less than 300, the recognition time of DFSA and packet DFSA is reduced by 11.7% ~ 16.1%; when the number of tags to be identified is more than 1000, the recognition time is reduced by 48.8% and 17.14% respectively compared with DFSA and packet DFSA.

Abstract:Pedestrian detection is an important branch in the field of object detection, and pedestrian detection algorithms have been well developed, but there exists severe occlusion between pedestrians in crowded scenes, which makes a great challenge for the detection task. To effectively alleviate this problem, this paper improves on YOLOv3 and proposes a single-stage dense pedestrian detection algorithm: Crowd-YOLO, which adds visible frame labeling information to the network to assist training, so that the network can predict both full-body frame and visible frame information to improve detection performance; proposes a time-frequency domain fused attention module (TFFAM), which adds frequency-domain channel attention and spatial attention to the network to redistribute features; uses data correlation upsampling instead of traditional bilinear interpolation to obtain a richer information representation of deep feature maps. This paper uses the very challenging large crowd scenario dataset CrowdHuman for training and testing. The experimental results show that the proposed method improves the AP50 metric by about 3.7% and the recall metric by 3.4% over the baseline, with the time-frequency domain fused attention module bringing a 2.3% AP performance gain. The experimental results verify the effectiveness of the proposed method in crowded scenarios.

Abstract:The defect detection and impact assessment of photovoltaic arrays are of great significance for improving the performance and reliability of their systems. Due to the problems of missing details and susceptibility to noise interference in the detection images of photovoltaic array hot spot defects, in order to be able to quickly identify defects and accurately analyze their damage, a set of systematic inspection schemes are proposed. Use a handheld thermal imager to take pictures of the photovoltaic array and transfer the acquired images to the computer, and convert the original Red-Green-Blue color mode (RGB) image into grayscale through grayscale processing image. Due to the shortcomings of traditional thermal imaging detection technology such as low efficiency and lack of defect measurement standards, this paper proposes an improved gray conversion algorithm. First, perform K-means clustering of grayscale images, and perform linear enhancement, it can linearly increase the gray value of each area. Then use threshold segmentation algorithm to perform regional correction of image color clusters. Finally, analyze the image quantitatively according to the defect degree table. Data and image combined to show the defects of the photovoltaic array. The experimental results show that compared with the traditional binarization processing algorithm, the deviation of the algorithm proposed in this paper is less than 2% in defect detection, and show the areas of slight defects and severe defects in detail. It also can suppress image non-uniform noise and improve the accuracy of detection.

Abstract:Based on multi-factor fusion, this paper proposes a new driving early warning method. First, combining the existing fatigue factors, a risk assessment criterion is proposed based on multiple factors, which overcomes traditional single-factor methods’ limitations in application and shortcomings of being vulnerable to external interference. Secondly, a detection network is proposed based on SSD, in which the backbone network VGG is replaced with the advanced MobileNetV3, fast target detection is achieved with a modified NMS layer, and finally multi-task detection is realized with newly designed multi-task detectors and loss functions. After transfer-learning with the pre-training weights, the tested detection accuracy rate is 95.7%, and the speed is 41fps, which is accurate and real-time.

Abstract:In order to reduce the influence of noise on image registration accuracy, an improved image anti noise registration algorithm based on high-order cumulant is proposed. Firstly, the image is deal with average value subtraction, and the third-order spectrum is obtained by using the discrete Fourier transform of the third-order cumulant, and then the normalized cross bispectrum is calculated to effectively suppress the influence of noise. Finally, the precise translation, rotation angle and scaling factor are obtained by inverse Fourier transform. The simulation results show that the improved algorithm can achieve more accurate registration of images with strong noise, and the maximum estimation errors of translation, rotation angle and scaling are only 0.58 pixel, 0.19° and 0.36% respectively, and the registered image has smaller root mean square error and large normalization peak correlation energy confidence, which further shows that the proposed algorithm has stronger adaptability and robustness to noise, so as to obtain more accurate registration image.

Abstract:In order to improve the prediction accuracy of medical diagnosis, a feature learning and classification stage combination method based on enhanced sparse self encoder and softmax regression is designed. In the feature learning of the sparse self encoder (SAE) network, the sparsity is realized by punishing the weight of the network, and the change is transmitted backward and the cost function is optimized iteratively. In the stage of softmax regression classification, the cross entropy of softmax classifier is optimized by small batch gradient descent method, and the model error is calculated with small batch data, and the model parameters are updated to achieve convergence. The prediction accuracy of the proposed method is 91%, 97% and 98% respectively for heart disease, cervical cancer and chronic kidney disease (CKD) data sets, and shows high feature learning and robust classification performance.

Abstract:In this paper, we have proposed a novel printed antenna with characteristics of miniaturization and triple-band, which is expected to be employed in Wireless Local Area Networks (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX). Based on a conventional monopole antenna, the proposed antenna can operate in three different resonant modes by loading branches and slots into the antenna body. The antenna body is printed on the FR4 with relative permittivity of 4.4 and the dimension of only 24 mm × 19 mm × 1 mm, which is fed by CPW. With three distinct resonance modes, the impedance bandwidth of the designed antenna can fully cover three desired bands of WLAN (2.4～2.48 GHz), (5.55～5.825 GHz) and WiMAX (3.4～3.6 GHz). The antenna was designed and simulated by HFSS and a corresponding experimental prototype has been fabricated and tested. Good agreement between the simulation and measurement is obtained, and measured results also presents that the antenna has good omnidirectional radiation with peak realized gain of 3.8 dBi, which can meet the requirements of WLAN/WiMAX wireless application.

Abstract:Aiming at the problems of fuzzy beamforming direction, low main lobe gain and high side lobe in non-overlapping fixed sector, an overlapping array algorithm for circular conformal was designed. In this algorithm, the circular array is divided into several 120° overlapping sectors, and the number of sectors and overlapping areas can be adjusted. At the same time, directed array and Taylor weighting are adopted to make the beam emitted in the desired direction located in the center of the divided sectors, so as to obtain the maximum gain. The results show that, compared with the non-overlapping circular arrays with fixed sector, the side-lobe suppression of the single-beam emitted by the overlapping circular arrays decreases from -10.16dB to -21.2dB. The sidelobe suppression decreased from -18.92dB to -24.18dB, and the main lobe gain increased from 10.76dB to 15.32dB. When transmitting eight beams, the main lobe of each beam points accurately without deviation and the side lobe is low. The results show that, compared with the traditional fixed array beamforming algorithm, the overlapping array algorithm performs better in main lobe pointing, main lobe gain and side lobe suppression.

Abstract:The onboard datalink system plays a significant role in civil aircraft systems nowadays. It should be developed to be faster and be equipped with higher stabilities so as to satisfy the increasing demands of communication. The onboard datalink system based on the IMA architecture is a new system and its performance has not been verified adequately. In order to verify the Required Communication Performance of this kind of datalink system, the paper designs and builds a simulation system, which including the onboard system, VHF link and the ground system. The ground system loads and records the time of 60 uplink messages and the according response messages based on the methods given in the ICAO Doc 9896. After calculating and analyzing the results, it comes to the conclusion that the datalink communication system based on the IMA architecture meets the RCP requirements.

Abstract:Aiming at the complexity of current DA conversion and its conditioning circuit of multichannel signal source, combined with the requirements for analog signal sources , a multichannel analog signal source based on FPGA and PCI bus is designed. The board takes FPGA as the system controller, PCI9054 as PCI bus protocol chip, 100V analog voltage is generated by boost chip lm5022, and the output is controlled by aqy277a Optical MOS Relay of NAIS company; 23 channels of 0-28v adjustable analog voltage are converted by 6 four channel DA conversion chip ad5504. Finally, the calibration coefficient of the upper computer is used to improve the accuracy of output voltage. The results show that the board can output the voltage reliably, and the stability is high, and meets the design requirements.

Abstract:Traditional phase noise measuring instruments are expensive, and have complex systems which limit them from being widely used in laboratories and large-scale industrial production tests. So, in this condition, a light and small phase noise measurement system is designed. Based on time-voltage conversion technology and by use of FPGA and single-chip hardware platform, the system can measure the phase-time difference sequence at the rising edge of the zero-crossing point of same frequency signals with small frequency difference and different frequency signals with high precision. According to the autocorrelation algorithm the Fourier transform, the system realizes the conversion of the time-domain phase-time difference sequence into phase noise and provide the display and storage of the test results of phase noise based on the upper computer software. According to final result of the experiment, the system reaches a measurement resolution of time difference sequence of 10-12, and keep a measurement error of phase noise in the offset carrier frequency range of 0～100kHz of less than 5dBc when compared with the PN8010 measuring instrument.

Abstract:Aiming at the problems of the traditional video traffic flow detection algorithm, such as single feature, poor weather robustness and easy to be blocked by vehicles, a traffic flow detection method combining temporal and spatial features was proposed. To the cross-correlation of foreground and background image blocking normalized values as a feature of testing vehicles through accumulation plan get space-time characteristic figure on time, on time accumulated figure to analysis the characteristic value, and the introduction of deep learning target detection algorithm assisted background updating and eliminate the problem such as vehicles for shade caused by the leak, and correction for pedestrians, bicycles and other interference factors to achieve the objective of the statistics of the number of cars. Experimental results show that,the accuracy of the algorithm in this paper can generally reach more than 91%, which is better than the traditional frame difference method and optical flow method in most cases. Moreover, the real-time performance is good, which can better meet the requirements of the traffic flow detection system.

Abstract:With the development of industrialization, more and more measurement equipment is applied in Ophthalmology. Before many ophthalmic operations, various biological parameters of anterior segment are usually measured precisely. The common biological parameters affecting the refractive power of human eyes include axial length, corneal refractive power, anterior chamber depth etc.This paper summarized the principle of optical coherence interference technology equipment on the market;and analyze the measurement of the key biological parameters of anterior segment.It aim to provide the reference for ophthalmic clinical research and technical evaluation of medical devices.

Abstract:In order to further improve the surface morphology characterization ability of atmospheric frequency modulated non-contact Atomic Force Microscope (NC-FM-AFM). In this paper, a high-precision driving displacement adjustment device is designed based on the atmospheric environment light path adjustment system. The stick slip high-precision driving mode is realized by using multiple stacked tangential piezoelectric ceramics. The adjustment accuracy reaches 2.6nm/V, which is higher than that of the conventional stepper motor, making the cantilever reflectance reach 26%. Based on the design of the high-precision displacement adjustment device, the system realizes the detection and feedback of the resonant frequency, where the resonant frequency f0 = 158.73 kHz, half maximum width ω=373.2Hz,Q = 564, the minimum detection sensitivity of the system is 80mHz, and the voltage noise density of the system is about 2.32 The overall noise of the system is 253.3 fm/√Hz. It lays a foundation for the characterization of the sample morphology.

Abstract:In order to enhance the interaction between robots and humans, the human-computer interaction is more intelligent and natural. A facial expression recognition method based on channel attention mechanism is proposed. Using the biped humanoid robot NAO as an experimental platform, a human-computer interaction system capable of facial expression recognition is designed. First, the facial expression recognition algorithm of the attention mechanism is trained through the RAF-DB data set. The training results show that the model can recognize 7 basic expressions (happy, angry, nauseous, fear, sad, surprised and natural). Its accuracy rate can reach 76.7%. Secondly, design the voice and actions of the NAO robot when facing different expressions, and finally, test the entire human-computer interaction system. The test results show that when the NAO robot receives the emotions recognized by the computer, it will speak and act like a human.