Search

In this paper, we propose an edge detector based on feature re-extraction (FRE) of a deep convolutional neural network to effectively utilize features extracted from each stage, and design a new loss function. The proposed detector is mainly composed of three modules: backbone, side-output, and feature fusion. The backbone module provides preliminary feature extraction; the side-output module makes network architecture more robustly map features from different stages of the backbone network to edge-pixel space by applying residual learning, and the feature fusion module generates the edge map. Generalization ability on the same distribution is verified using the BSDS500 dataset, achieving optimal dataset scale (ODS) F-score = 0.804. Cross-distribution generalization ability is verified on the NYUDv2 dataset, achieving ODS F-score = 0.701. In addition, we find that freezing backbone network can significantly speed up training process, without much overall accuracy loss (ODS F-score of 0.791 after 5.4k iterations).

In order to expand the measuring range of the exposure sensor and solve the current fluctuation caused by the memristor resistance, a novel exposure sensor based on reverse series memristor is proposed. The exposure sensor mainly consists of the photoresistor, the current limiting resistor and the reverse series memristor. The resistance of photoresistor varies with the illuminance, causing the loop current change. Based on the memory feature of the memristor, its resistance can be used to characterize the integral value of the illuminance for a period of time. Thus the measurement of the exposure can be realized by the exposure sensor based on reverse series memristor. In the exposure sensor, two series memristors constitute the reverse series memristor and they are connected in serial oppositely. And the sum of their normalized thicknesses is 1. Experimental results show that the exposure sensor based on reverse series memristor can measure the exposure and its measuring range is larger than other measurement methods. The measuring range is from 0 to 600 lx·s when the illuminance is 100 lx. With the increase of illuminance, the measuring range of the sensor will expand while the sensitivity will decrease. Because the resistance of the reverse series memristor almost remains unchanged during measuring exposure (the standard deviation of the change is only 0.43 Ω), the influence of the total resistance’ increase on the loop current can be avoided. Thus it can avoid the impact on the measurement of the exposure and reduce the error introduced by the change of the memristors resistance. As the number of memristors increases, the measuring range will expand and the sensitivity will improve, but the symmetry of the reverse series memristor will deteriorate. Hence the number of memristors can’t be excessively large. The variation tendency of the memristor resistance curve and the normalized thickness curve are consistent, and they rise along with the increase of the exposure. In addition, the measuring range of the exposure sensor will expand gradually while the sensitivity will decrease as the resistance of the current limiting resistor increases.

This study presents an ideal synchronous buck current regulator for variety of light-emitting diode (LED) loads from wide input voltage range. By using high-side power switch matched sense, the regulator maintains high current accuracy and high system efficiency. The adjustable current sense threshold provides a full-range analogue dimming and the fast output enable/disable function allows for high-frequency pulse-width modulation (PWM) dimming. In addition, the two dimming methods are easy to implement and have highly linear range. An adaptive off-time control is adopted to regulate an accurate constant current for its fast response and no need for control loop compensation, while its disadvantage of variation of switching frequency is overcome. The proposed circuit has been fabricated with 0.35 μm 40 V bipolar-CMOS-DMOS (BCD) process successfully. The experimental results confirm that the LED driver can operate within 6–40 V input voltage, and can drive a 1–10 output series connected LEDs. The switching frequency is fixed at 500 kHz with a variation of ±2%. The measured system peak efficiency is up to 95% at 1 A LED current and 10 V output voltage. The settling time at the PWM rising edge is

The ZnO waveguide layer for the Love wave humidity sensor was fabricated by radio frequency (RF) magnetron sputtering technique using ZnO as the target material. To investigate the effect of RF magnetron sputtering temperature on the ZnO waveguide layer and Love wave device, a series of Love wave devices with ZnO waveguide layer were fabricated at different sputtering temperatures. The crystal orientation and microstructure of ZnO waveguide was characterized and analyzed, and the response characteristics of the Love wave device were analyzed by network analyzer. Furthermore, a humidity measurement system is designed, and the performance of the Love wave humidity sensor was measured and analyzed. The research results illustrate that the performance of the ZnO waveguide layer is improved when the sputtering temperature changes from 25 &deg, C to 150 &deg, C. However, when the sputtering temperature increases from 150 &deg, C to 200 &deg, C, the performance of the ZnO waveguide layer is degraded. Compared with the other sputtering temperatures, the ZnO waveguide layer fabricated at 150 &deg, C has the best c-axis orientation and the largest average grain size (53.36 nm). The Love wave device has the lowest insertion loss at 150 &deg, C. In addition, when the temperature of the measurement chamber is 25 &deg, C and the relative humidity is in the range of 10% to 80%, the fabricated Love wave humidity sensor with ZnO waveguide layer has good reproducibility and long-term stability. Moreover, the Love wave humidity sensor has high sensitivity of 6.43 kHz/RH and the largest hysteresis error of the sensor is 6%.

Virtual reality is a new technology with wide application prospect in recent years. At present, virtual reality technology has been widely used in entertainment games, architectural design, medical and other fields. Based on the concept, characteristics and application of virtual reality technology, this paper introduces the key technologies needed to realize virtual reality, and then introduces the recent hot research direction of virtual reality, such as 3D model retrieval technology, 3D model watermarking technology, distribution type virtual environment communication technology.

To solve the wide range of the output voltage, difficult storage and not unified interface of solar cell, a novel solar charging system was proposed. The system consists of the solar panel, the voltage regulator circuit, the battery charge management circuit, the lithium battery, the booster circuit and the USB output circuit. The voltage regulator circuit can convert the output voltage of solar panel into 5V. By means of the charge management circuit, the energy is stored in the lithium battery, and it can be provided to the load via the booster circuit and USB interface, which can achieve the goal of the conversion, storage and utilization from solar to electrical energy. Under the condition of effective illumination between 10:00 and 16:00, the solar charging system was tested for 7 days. Experimental results show that the output voltage always maintained at 5V during the test. The output voltage of lithium battery reaches to 4.2V after four hours, and the output voltage of USB port always stabilizes at about 5V.

To solve complex measurement and difficult remote operation in the test for frequency response characteristic of SAW device, an automatic test system for frequency response characteristic of SAW device based on vector network analyzer is proposed. The system consists of the vector network analyzer, the crossover cable, the computer, the fixtures and the SAW device. The user interface of test system is developed with the VB language. By means of calling the VISA-COM library, the SCPI commands can send to the vector network analyzer. Many functions of the automatic test system for frequency response characteristic of SAW device include the settings of measurement parameters, the measurement calibration, the data storage, the data display, the data transmission, the marker analysis and the data output. By the actual measurement of a SAW device with the center frequency at 101.764MHz, the experimental results show that the transmission loss of SAW device is-27.532dB, and the reflection loss is-7.715 dB.

In order to achieve the wireless operation of the data collected and system monitoring in the weighing equipment, a wireless weighing system design was proposed. This scheme combines with the weighing control technology and the wireless communications technology. The weighing system includes the pressure sensor, the signal processing module, the microprocessors, wireless data transceiver module, the infrared module, the memory module, the display module and the control module. Based on the experiment of ten different targets ranged from 5kg to 50kg, the wireless weighing system was measured and analyzed. Experimental results show that the maximum error rate of the wireless weighing system is 0.2%, and wireless transmission distance reaches two hundred meters.

Aiming at the loss of image boundary information and the blurred image details in the classical median filtering algorithm, the improved median filtering algorithm based on FPGA (Field Programmable Gate Array) is proposed. In the improved median filtering algorithm, the borders mirroring and threshold comparing are adopted, and the loss of the image boundary information is lowed and the detailed information of image is preserved. The improved median filtering algorithm based on FPGA consists of the filter template generating module, the median grayscale computing module and threshold comparing module. The experimental results show that that the NMSE (normalized mean square errors) of the image filtered with the improved median filtering algorithm is lowed by 25.6%, and the operating efficiency is improved by 16% comparing with the classical median filtering algorithm.

a b s t r a c t ZnO nanowire based surface acoustic wave ultraviolet (UV) detector is highly desirable for UV radiation detection. However, its slow recovery process due to the surface effect of ZnO nanowires has become a crucial issue. In this paper, a simple method of poly(3,4-ethylenedioxythiophene) (PEDOT) surface coating by the chemical polymerization is proposed and experimentally proved to improve the recovery process significantly. According to the photoconductive effect and the acoustoelectric effect, the suppression of ZnO nanowires' surface effect and the fast recombination approach of excess carriers provided by the PEDOT layer are responsible for the improvement of the recovery process.

Based on the analysis of the overshoot during the process of short-circuit recovery, an improved hiccup mode protection technique with effective overshoot suppression is presented in this paper. The hiccup mode is activated by the error amplifier (EA) output rather than the feedback voltage. And when the voltage exceeds the high-clamping voltage, the soft-start voltage will be quickly discharged to zero and a new soft-start cycle will attempt to restart the converter. The proposed control method makes the EA output voltage rapidly decline once short-circuit recovery happens, which is very effective for the suppression of overshoot. In addition, the circuit has combined with a foldback current limiting method to further improve the effect of short-circuit protection and overshoot suppression. The proposed technique has been successfully applied to a peak current mode buck converter with Nuvoton 0.6-μm 5 V/18 V Low-Vgs CDMOS process. The experimental results show that even in extreme cases, this method can effectively suppress the overshoot and the overshoot is almost zero.

The surface acoustic wave (SAW) ultraviolet (UV) detector based on zinc oxide (ZnO) nanowire sensing layer was developed and fabricated in this paper. To improve the SAW device's response characteristics, inter-digital transducers (IDTs) apodized by Morlet wavelet function and multiple couplers (MSC) were applied. ZnO nanowire materials were synthesized by Zinc thermal evaporation method. The ZnO nanowire sensing layer was coated onto the propagating area of the SAW devices, namely the sensing area, by transfer method as well as the multi-crystal ZnO sensing layer was deposited onto another device by magnetron sputtering for comparison. It was found that ZnO nanowire layer itself shows enhanced UV photoelectric response characteristics compared to sputtered ZnO film layer, which is acquired by characterizing their optical and photoelectrical properties. Under illumination of a UV light source, central frequency shifts of the two UV detectors were measured. An average central frequency shift of over 65 kHz of the UV detector based on ZnO nanowire layer was observed under 150 μW/cm2 365 nm illumination for several on–off cycles while the one of the other detector was only about 8 kHz. Moreover, the results indicate that the ZnO nanowire layer based SAW UV detector has good stability and repeatability. This kind of SAW UV detector with high sensitivity presents the potential for practical UV detection applications.

In order to suppress the inrush current at start-up stage for synchronous boost converters, a novel start-up circuit with synchronous power-switch current-limit is proposed. A current sensing circuit with high accuracy for the synchronous power-switch and a linear feedback loop of current-limit are designed. The current-limit function is only enabled at start-up stage. In addition, the body node of the synchronous power-switches is supplied by a back-to-back diode structure from the input voltage and the output voltage, respectively, which effectively avoids the conduction of parasitic body diode on synchronous power-switches. The proposed technique has been successfully applied to a synchronous boost converter with 0.18μm 5 V CMOS process successfully. The experimental results show that the proposed method can effectively suppress the inrush current through synchronous power switch, and the output voltage rises smoothly without overshot.

RT（X-Radiography Testing） is a very import inspection method for detecting engine blade crack, and the defect is identified by person distinguishing the film for traditional RT. The traditional method is involved in high mistake and missed examining rate and low efficiency. It is great significance to blade integrity and flight safety that the crack can be quickly distinguished. In the paper, adopting a adaptive segmenting algorithm based on OTSU to quickly distinguish the crack on the blade image, and it can definite the threshold facing different gray image, and can reliably inspect the cracks which detection rate was 98%. The recognition accuracy for crack can reach 0.16mm Simulation result verify that the method is very effective on adaptively segmenting the blade image according to the threshold for crack inspection

The positioning accuracy can bring a great impact on inspecting defect for Aero-engine blade. The high or low pressure rotor of engine is generally driven by manual when blade’s defect is inspected. Frequently，False detection and missed happens due to match failure between two persons. Adopting a high-resolution, high-accuracy algorithm based on FPGA to design automotive equipment for high or low rotor . The Frequency range to step motor is 1Hz / s to 65536Hz / s, resolution is 1Hz,and positioning accuracy for blade can be up to 1mm.Resolving the questions of missing detectable rates made by manual during inspection in the paper, and increasing efficiency for inspection and the reliability of the experimental result. Experiment results show that this equipment can meet the challenge of the high-accuracy regulating speed for blade’s inspection.

Carbon dioxide (CO2) gas sensor using surface acoustic wave (SAW) device based on Zinc oxide (ZnO) was developed and fabricated in this paper. The center frequency of SAW device is 203.528 MHz. The input and two output interdigital transducers (IDT) apodized by Morlet wavelet function can improve the side lobe rejection compared with uniform IDT. The ZnO film sensitive to CO2 gas was fabricated in measurement acoustic track of SAW device. Experiments results confirm that the CO2 gas sensor using SAW device based on ZnO film has good response characteristics to different concentrations CO2 gas. Furthermore, the CO2 gas sensor using SAW device based on ZnO film has good stability and linearity.

In the design process of surface acoustic wave (SAW) device based on multistrip coupler (MSC), the characteristics of interdigital transducer (IDT) and device can not been directly achieved, and the layout structure of device can not be observed and checked. To solve some problems, the design platform of SAW device based MSC was realized in the Matlab design environment using the modular design. The design platform of SAW device based MSC consists of layout simulation module, characteristics simulation module and data output module. By means of realizing a SAW device based MSC with center frequency at 51.293MHz, the comparison and analysis between the design results and the actual test results are presented. Experiments results confirm that the platform can correctly design the device layout. The device characteristics achieved by the design platform are in good agreement with the actual measurement results by the network analyzer.

The current self-organizing feature map (SOFM) neural network algorithm used for image compression, of which a large amount of network training time and the blocking effect in the reconstructed image existed in codebook design vector calculation. Based on the above issue, this paper proposed an improved SOFM. The new SOFM introduced normalized distance between the sum of input vectors and the sum of the codeword vectors as a constraint in the process of searching for the winning neuron, which can remove redundant Euclidean distance calculation in the competitive process. Furthermore, this paper has done image compression by combining wavelet transform with the improved SOFM (WT & improved SOFM). The method firstly conducted wavelet decomposition for the image, retained low-frequency sub-band, then put the high-frequency sub-band into improved SOFM network, and achieved the purpose of compression. Experimental results showed that this algorithm can greatly reduce the network training time and enhance the learning efficiency of neural network, while effectively improve the PSNR (increased 0.6dB) of reconstructed.

To meet the requirements of smoothness and flexibility, an intelligent track-searching vehicle is designed to run fast and smoothly on different tracks. It is equipped with a MC9S12DG128 SCM as core, a steering engine, a motor-control module and other modules. The continuous path recognition algorithm is applied to collect track information, and the optimized PID control algorithm is used to control the intelligent vehicle’s steering engine and motor. The experimental results show that the detection accuracy of intelligent vehicle is significantly increased; its sensitivity and stability are also obviously improved, achieving the fundamental goal of high speed of intelligent track-searching vehicle.

A nitrogen dioxide (NO 2 ) gas sensor using dual track surface acoustic wave (SAW) device was developed and fabricated in this paper. The dual track architecture and the MSCs were skillfully applied to the sensor. The external perturbations were eliminated by the dual track architecture, and the bulk acoustic wave (BAW) was suppressed by Multistrip coupler (MSC). The input IDT apodized by Morlet wavelet function can improve the side lobe rejection compared with uniform IDT. Utilizing Tungsten powders, hydrogen peroxide, absolute methanol and polyvinylpyrrolidone as raw materials, the micro-porous network Tungsten trioxide (WO 3 ) film sensitive to NO 2 gas was fabricated in measurement acoustic track of dual track SAW device. Experiments results confirm that the NO 2 gas sensor using dual track SAW device has good response characteristics to different concentrations NO 2 gas from 0.5 ppm to 10 ppm. Furthermore, the NO 2 gas sensor using dual track SAW device has good reproducibility and stability.

In this paper, a sensor architecture of a dual track surface acoustic wave (SAW) gas sensor using three-interdigitated transducers (IDTs) and two-multistrip couplers (MSCs) is proposed. The dual track SAW gas sensor consists of three IDTs and two MSCs fabricated on 128degY-X LiNbO3 piezoelectric substrate. Dual track structure and MSCs are incorporated into the sensor, thus the perturbations of the measurement signal from external environment are eliminated, and spurious responses caused by bulk acoustic waves (BAWs) are suppressed. Furthermore, the side lobe rejection is better than that of SAW sensors with uniform IDTs due to input IDT apodized by Morlet wavelet function. An experiment of dual track SAW gas sensor coated with polyaniline film sensitive to SO2 gas is presented. Experiment results confirm that the sensor has good reproducibility and response properties to SO2 gas at different concentrations. In the measurement ranging from 312 ppb to 20 ppm, the sensor has good linearity, and its sensitivity is approximately 6.8 KHz/ppm.

In this paper, the relationship between the center frequency and radius of bandwidth and its effect on the frequency band characteristics of dyadic wavelet processor array using surface acoustic wave (SAW) devices are studied, and an optimal frequency band design scheme is proposed. For an arbitrary scale wavelet processor, we proposed that the center frequency is defined to three times of the radius of frequency bandwidth. The frequency band design scheme ensures that the frequency band coverage factor is equal to 100% at -3 dB, which avoid the signal loss caused by the discrete frequency band and the device waste caused by the redundant frequency band. With the frequency band design scheme, an experiment of implementing a dyadic wavelet processor array using SAW devices with five scales is presented. Experimental results confirm that the frequency band coverage factor equals 100% at -3 dB without discrete and redundant frequency band.

In this paper, we propose dual track architecture and time synchronous scheme for wavelet reconstruction processor using surface acoustic wave (SAW) device based on multistripe coupler (MSC). An arbitrary scale wavelet reconstruction processor with dual track architecture consists of a wavelet interdigital transducer (IDT) apodized by the envelope of wavelet function, two MSCs, and two reconstruction wavelet IDTs apodized by the envelope of identical reconstruction wavelet function. The SAW launched by wavelet IDT is bidirectional. Two reconstruction wavelet IDTs with identical design parameter are symmetrically deposited on the dual track of wavelet reconstruction processor. Therefore, the performances of wavelet reconstruction processor were improved due to bidirectional SAW received by two reconstruction wavelet IDTs. Furthermore, the delay time characteristic of SAW propagating on crystals substrate surface was skillfully applied to compensate the time asynchronous problem among wavelet reconstruction processor. This means ensures that all scale processors in wavelet reconstruction processor have identical response time. An experiment of wavelet reconstruction processor with dual track architecture and time synchronous scheme was presented. Experimental results confirm that the performances of wavelet reconstruction processor are improved, and time synchronous is realized in this wavelet reconstruction processor with three scales.

In this paper, we propose to implement a time synchronous dyadic wavelet processor array with surface acoustic wave devices. An arbitrary dyadic wavelet scale processor consists of a wavelet interdigital transducer (IDT) apodized by the envelope of a wavelet function and a uniform IDT. A dyadic wavelet processor array consists of a multiscale wavelet processor using a surface acoustic wave (SAW) device array based on scale dyadic dilation. The delay time difference between different scale processors in the dyadic wavelet processor array is compensated by the delay time characteristic of the SAW propagating on the crystal substrate surface, which ensures that the wavelet transform result output by the dyadic wavelet processor array can correctly characterize the time–frequency properties of the input signal. An experiment implementing a time synchronous wavelet processor array consisting of three scale processors with SAW devices is presented. Experimental results confirm that the experimental frequency response curves are in good agreement with the theoretical frequency response curve over 30 dB, and three wavelet scale processors have the same response time.

We propose to implement wavelet transform and reconstruction processor with surface acoustic wave (SAW) device based on multistrip coupler (MSC). Uniform interdigital transducer (IDT) and reconstruction wavelet IDT were grated on two output tracks of wavelet IDT, respectively. This architecture enables wavelet transform and wavelet reconstruction operation to be simultaneously implemented in one processor. Furthermore, second insertion loss is overcome in wavelet reconstruction processor.

A novel model of vehicle license plate (VLP) recognition system was proposed in this paper. The model of VLP recognition system consists of preprocessing, location, character segmentation and the VLP character recognition. The image graying and binary technology were applied to VLP preprocessing. The Sobel edge detection operator was incorporated into the VLP location. The vertical projection method was used to character segmentation of VLP. The VLP character recognition adopted the BP (Back Propagation) neural network technology. Experiments results conform that the VLP recognition system can achieve a good recognition result, and the correct rate of VLP recognition is about 94%. Furthermore, in order to overcome some unsatisfactory conditions for the VLP, a train module of BP neural network was integrated in the VLP recognition system.

To improve the performances of surface acoustic wave (SAW) device, the architecture of dual track SAW device was proposed in this paper. The dual track architecture and the multistripe couplers (MSCs) were skillfully applied to the dual track SAW device. The bulk acoustic wave (BAW) excited by input IDT was separated and eliminated by the full transfer MSC. The bidirectional SAW launched by input interdigital transducer (IDT) can be totally received by two output IDTs connected in parallel. The triple transit echo signals were suppressed by dual track in input IDT. Furthermore, the dummy electrodes were used as eliminate the phase front distortion of waves propagating through apodized IDTs, and split electrodes were used as minimize acoustic reflections within transducers. By means of a dual track SAW device with center frequency at 203.559 MHz, the results of test and analysis are presented. Experiments results confirm that the dual track SAW device has good response characteristics in frequency domain and time domain, and the passband ripples and the side lobes are acceptable and better than ones of traditional SAW device.

A ZnO nanomaterial-based surface acoustic wave (SAW) ultraviolet (UV) detector is highly desirable for UV radiation detection due to its high sensitivity. In this work, firstly the ZnO nanomaterial-based SAW UV detectors operating at three different frequencies (?50, ?100 and ?200?MHz) were fabricated. Then, four ZnO nanomaterial sensing layers with different thicknesses were synthesized on the SAW UV detectors operating at ?200?MHz. The morphology, crystallization and photoluminescence of ZnO nanomaterial sensing layers were characterized using the scanning electron microscopy, transmission electron microscopy, x-ray diffraction and fluorescence spectrometer, respectively. The SAW UV detectors based on different operating frequencies and ZnO nanomaterial sensing layer's thicknesses were exposed under UV illumination at a wavelength of 365?nm and their UV responses were measured. The experimental results indicate that the frequency shift of ZnO nanomaterial-based SAW UV detector can be significantly improved by increasing operating frequency or ZnO nanomaterial sensing layer's thickness. Furthermore, the detectors exhibit good selectivity of UV illumination, an ultrahigh UV sensitivity of about 9.6?ppm (?W?cm?2)?1?and fast transient properties. The experimental results agree well with the acousto-electric effect theory. What deserves to be noted is that, under a UV intensity of 150??W cm?2, the frequency shift of the SAW UV detector operating at ?50?MHz with a thin ZnO nanomaterial sensing layer was only ?50?kHz while that of the SAW UV detector operating at ?200?MHz with a thick ZnO nanomaterial sensing layer could reach ?292?kHz. These results suggest the huge potential applications of ultra-sensitive ZnO nanomaterial-based SAW UV detectors for remote wireless UV and radiation monitoring.

In this paper, we propose a sulfur hexafluoride (SF6) gas sensor using a dual track surface acoustic wave (SAW) device based on multi-wall carbon nanotubes (MWCNTs). The sensor consists of a dual track SAW device and MWCNT film sensitive to SF6 gas. The measurement acoustic track of the sensor is coated with an MWCNT film treated by an acid process which selectively absorbs SF6 gas, while the reference acoustic track is uncoated. Experimental results confirm that the SF6 gas sensor using a dual track SAW device based on multi-wall CNTs has good response characteristics to different concentrations of SF6 gas from 0.5 to 20 ppm. The sensor has good linearity and reproducibility, and its sensitivity is approximately 7.4 kHz ppm−1. Furthermore, the sensor has a smaller cross-sensitivity for SO2 and HF.