Search

Many applications of wireless power transmission (WPT) require high misalignment tolerance. However, the transmission power of WPT is highly susceptible to the misalignment. To solve this problem, the magnetic resonant WPT control method with high misalignment tolerance is proposed here. First, based on the general mutual model, the complex ratio transformer model is established. This model gives an intuitive physical picture in power transmission process and frequency splitting phenomenon. Second, approximately constant voltage gain at frequency splitting point in a wide range of misalignment is analysed. Considering this frequency splitting characteristics of Magnetic resonant WPT, the maximum peak point tracking control methods for wide misalignment, maintaining constant output power is proposed. Finally, the corresponding simulation and experimental validation is given, demonstrating the feasibility of the control method. When the misalignment reached 40%, the fluctuation of the output voltage will be

The damage detection of the wind turbine (WT) blade is an important aspect of its health situation monitoring. In order to catch small damages, it is necessary to stitch the multi segment images of the blade to obtain a high resolution image. In image stitching, a blurring of the image is carried out to reduce the influence of noise. However, the preprocessing may decrease the amount of feature points and cannot avoid the interaction of feature points in the background and the target parts. To overcome these problems, a preprocessing method based on background removal is proposed. The idea of the method is to carry out image segmentation to get the background part, then the intensities of pixels in background part are replaced by a same value, such as average intensity. Employing the proposed preprocessing method, the image stitching is implemented on several groups of WT blade images. Feature points extraction result are compared between the proposed and the blurring preprocessing, which shows that the proposed method is more robust to the parameters in image stitching process. Moreover, the capability about image stitching and multi-image stitching of the proposed method is well verified by the experiment results.

Wind energy, as a renewable energy source, has attracted great attention of many countries. It is converted into electricity by the important machine, wind turbine (WT). With the fast growing of WT capacity in the world, the costs of monitoring and maintaining increase year by year. One necessary part of these costs is for blades health situation monitoring, which directly affects effectiveness and safety of WT. Thus, the damage detection of the blades is of great significance. The blades suffer from sunshine, acid rain, sand attack, and others, which may cause kinds of damages, such as skin abscission, surface crack, and sand hole. Aiming at surface damage detection of the blades, the paper proposed a method based on variational image segmentation model. At beginning, an idea that objects in an image are left along with detection of the background part is present, and it is changed into an optimization problem by using the level set method and 1-D Heaviside function. Then the corresponding gradient descent minimization algorithm is derived. In the experimental part, a large number of blade images with surface damages are tested by applying the proposed method, and damages are all detected successfully. Moreover, the segmentation results of the noise images show that our method is robust to noise. This paper can provide effective technical support for surface damage detection of WT blades in-service.

Cell inconsistency affect battery life and driving safety. In order to solve the accuracy problem of online prediction of cell inconsistency of power battery, battery characteristic analysis based on of vehicle network big data is proceeded, health indicator(HI), based on the cell terminal voltage difference,is proposed through the degradation model; As the similar distribution of cell terminal voltage difference between battery discharge conditions, the health indicator sequence based on SOC(State of Charge) is constructed, and the next health indicator is predicted by Gaussian process regression. The prediction results show that the method requires less training samples and less hardware resources, and the overall prediction accuracy is not less than 85%, which can meet the practical requirements.

OBJECTIVETo assess the effectiveness of acupuncture for the treatment of functional constipation (FC).METHODSThe literature was searched for randomized controlled trials (RCTs) comparing acupuncture with medical treatment; no medical treatment, placebo acupuncture, and sham acupuncture in patients with FC were searched. Data were extracted by two independent reviewers using standard data extraction forms. Risk of bias for each RCT was assessed using a modified Oxford 5-point quality scale. Data were pooled according to intervention and treatment course. Parameters evaluated included effectiveness/invalidity, Cleveland Clinic score (CCS), colon transit time (CTT) and adverse effects.RESULTSNineteen studies involving 1679 participants were eligible for inclusion; of these studies, 16 were published in Chinese and three in English. Risks of bias were high. Acupuncture was significantly superior to medication therapy in short-term (effectiveness / invalidity, P = 0.0009; CCS, P = 0.02) and long-term (effectiveness / invalidity, P = 0.004; CCS, P = 0.04; CCT, P < 0.0001) effectiveness. A short treatment course of less than 15 days was sufficient. The likelihood of adverse effects was significantly lower for acupuncture than for medication therapy (P = 0.002).CONCLUSIONCompared with medication, acupuncture was more effective and had a lower adverse effect rate in the treatment of FC. A short treatment course of two weeks was sufficient for a good effect. However, the poor quality of the included trials indicates the need for well-designed RCTs, including adequate sample size and a reasonable placebo control, to assess the effectiveness of acupuncture for FC.

The internal hydraulic fluid tubing in central shaft is a critical part of pitch adjusting paddle in the ship propulsion system. The failure of screw pairs of internal hydraulic fluid tubing will result in a loss of propulsion. This real accident has happened on a ship. In order to determine the reason for the tangential anti-loose dowel falling out from the screw pairs, 380.5h and 147h alternating torque and vibration environment tests are completed on two samples with difference of manufacturing processing. The result shows that alternating torque and vibration combined stress is the synthesis stress for the dowel falling out from dowel hole. The basic reason is the larger fit clearance between dowel and dowel hole. This clearance is suggested to be manufactured below 0.2∽0.3mm, and the value of diameter for piercing outside the dowel hole should be greater than 1.95mm.

This paper introduces an automatic calibrated pure electric (EV) mode of automatic switching based on bus road conditions. The entire vehicular control system collects bus road spectra using specific methods, identifies if the direction of the bus is along the predetermined bus lane, and records the positions where the driver manually switches the model, to finally implement an automatic EV switchover method function along bus lane roads. This method enables the flexible calibration of roads where EV mode is to be used, and implements automatic switching to avoid running on uphill roads in EV mode in order to decrease the labor intensity of drivers.

This paper puts forward a complete track forecasting models, using Kalman filter to track and predict the movement of objects without prior knowledge. Use the extracted Harris corner to calculate optical flow between two frames by L-K pyramid method, getting the convex hull of moving objects by optical flow clustering to separate the moving objects from background. Tracking and predicting the gravity of moving objects convex hull can solve the occlusion and separation problem between moving objects. Computer simulation and field test results show that the proposed method has higher tracking accuracy, and small amount of calculation.

Linear motor is applied in the seismic source system of deep well seismic wave exploration, which belongs to international cutting-edge techniques of the exploration industry. Compared to traditional blasting techniques, the technique has better safety performance and lower cost. It is concluded that the setting basic frequency is a critical factor for start-up force of the linear motor in the seismic source system based on the experiment and relative data. The concept of practical efficiency is proposed. In addition, the performance of the linear motor was improved significantly by analyzing relative data curves between inverter output frequencies, line voltage of the linear motor and the start-up force of the linear motor.

Aiming at the problem that routing security for Geographic information cannot be guaranteed, a Secure Geographic based Routing Protocol of Aeronautical Ad hoc Networks (S-GRP) is proposed. Through identity-based public key cryptosystem, it makes authentication for neighbor node and establish a shared secret in the neighbor discovery phase, and then makes signcryption for data in the data for-warding phase. When in the next hop selection, it makes an integrated assessment for node location-speed factor and trust factor, selecting the optimal next hop. Security analysis and performance analysis for S-GPR show that the algorithm is effective and feasible.

We developed a rat-robot system based on optogenetic techniques for the precise freezing behavior. Rat-robots were built up by optogenetic modulation at the dlPAG of rat brains. We conducted track navigation for the rat-robots and found they were able to exhibit precise freezing at given positions with high spatiotemporal accuracy. Different types of optical stimulation were compared and their influence on the rat-robots was investigated. Furthermore we recorded the neural electrical activity in real time during the optical stimulation. The system could be used to explore the mechanism of freezing behaviors and to build up a more integrated rat-robot navigation system based on optical modulations.

To effectively write and read the calibration coefficients used in LED panel display control system,a display calibration coefficient configuration system based on USB interface and FPGA was developed.Firstly,the serial flash and its application in LED display systems were introduced.Next,an electrical circuit is built,including a FPGA chip and a USB peripheral controller chip.Finally several programs were developed,including a USB firmware,a PC user program and a configuration program for the FPGA.Experiments show that the calibration coefficients can be correctly written and read with this system.Each sector of the flash can be erased in 0.6 s.The data can be written in 2.3 Mbit/s and read in nearly 30 Mbit/s.This system is easy to use,and it can take an important role in the calibration coefficients operation of the LED panel display control system.

In order to fast acquire the gamut boundary of a LED display panel,an iterative method was proposed for the calculation of intersections between mapping lines and the gamut boundary,which was further used to get the fitting gamut boundary in each hue plane.Firstly,the judgment method if a color was in the LED display panel color gamut was supplied based on the colorimetric principles of LED display.And then,in the CIELAB uniform color space,it analyzed the iteration principle,determined the initial values for iteration,and carried out the analysis of calculation precision and speed.Finally,with D65 as reference,a LED display panel boundary fitting experiment and its color difference analysis were carried out in the same hue plane.Experiment result shows that the fitting boundary is very smooth after 11 iterations,and the maximum color difference between the true value and calculated value of the gamut boundary point on every mapping line is only 0.23.Compared with the interpolation methods,the maximum color difference is decreased and calculation speed is increased by an order of magnitude respectively.The method suggested could meet the needs of gamut analysis and gamut mapping with other display devices for the LED display panel in both the calculation precision and speed.

Stack nanocrystalline-Si (nc-Si) based metal insulator semiconductor memory structure was fabricated by plasma enhanced chemical vapor deposition. The doubly stacked layers of nc-Si with the thickness of about 5 nm were fabricated by the layer-by-layer deposition technique with silane and hydrogen mixture gas. Capacitance-Voltage (C-V) measurements were used to investigate electron tunnel and storage characteristic. Abnormal capacitance hysteresis phenomena are obtained. The C-V results show that the flatband voltage increases at first, then decreases and finally increases, exhibiting a clear deep at gate voltage of 9 V. The charge transfer effect model was put forward to explain the electron storage and discharging mechanism of the stacked nc-Si based memory structure. The decreasing of flatband voltage at moderate programming bias is attributed to the transfer of electrons from the lower nc-Si layer to the upper nc-Si layer.

In this paper, we focus on how to identify the influence of device cause by substrate damage issue via nanoprobing analysis, and inferring that the equivalent mathematical models was application to describe the corresponding electrical data in a device with substrate damage issue. A case study was presented to verify that poor Poly etching process control caused substrate damage issue, and this issue can be identified via physical failure analysis (PFA) method (e.g. Transmission Electron Microscope (TEM) and Focus Ion Beam (FIB) techniques) and nanoprobing analysis method.

To address the simultaneous fault diagnosis problem, a Multi-Label approach that makes use of Relevance vector machines (RVM), as the learning algorithm, is proposed to decrease the number of fault identification models and deal simultaneous fault diagnosis problems. The system is proved to be efficient by the simulation test on the Tennessee Eastman Process (TEP).

One nearspace hypersonic aircraft model based on pneumatic/ thrust vectoring composite control was built, compound controler optimization scheme was adopted to cooperate pneumatic/thrust vectoring compound controler equivalent dynamic characteristic to reference model during dynamic assign.The simulation result shows the arithmetic availability.

In this paper, the shock waves induced by a nanosecond pulsed laser in copper target are studied and the relative pressures of shock waves are measured by using the piezoelectric polyvinylidene fluoride piezoelectric sensors. The evolutions of the relative pressures of shock waves with laser pulse energy and target thickness are discussed. Experimental results show that the pressure of shock wave is 2.1 MPa when the nanosecond pulsed laser with an energy of 500 mJ irradiates on a 2 mm thick copper target. When the laser energy increases from 200 to 500 mJ, the pressures of shock wave can increase 162% and 231%, with the target thickness values being 2 and 4 mm respectively. But when the thickness of the copper target increases from 2 to 6 mm, the pressures of shock waves with laser pulse energies of 400 and 500 mJ are reduced by 32% and 49%, respectively.

Dense Si nanostructures embedded in silicon nitride prepared by plasma-enhanced chemical vapor deposition (PECVD) was used as luminescence active layer to fabricate light-emitting diodes based on p-Si/SiN-based emitter/AZO structure. Visible electroluminescence from the device was observed at room temperature. It is found that the electroluminescence intensity of the device can be further enhanced significantly by inserting an ultrathin nanocrystalline Si layer between the p-Si substrate and SiN-based emitter as a hole barrier layer. Moreover, the electroluminescence efficiency is increased by more than 80% as compared to the decice without the nc-Si barrier layer.

Laser crystallization of amorphous Si thin films is one of reliable method of preparing nanocrystalline silicon with high density and controllable size. In the present work, molecular dynamics simulation based on Tersoff potential was used to study the laser crystallization process of ultrathin amorphous silicon film (2.7 nm) on amorphous silicon nitride substrate. The influence of laser fluences on the crystallization and formation of nanocrystalline Si was investigated. It was found that there exists a laser fluence window in which nucleation and growth of nanocrystalline Si can be realized, which is in agreement with our previous experimental observations. The nucleation and growth processes in microscopic scale were simulated and the size of formed nanocrystalline Si was limited in both vertical and lateral directions by the film thickness and the formation of grain boundaries.

In order to solve the problem one detection algorithm can only detect one kind of network covert channel, The detection approach hierarchical and density based cluster was purposed. Because the coding scheme of the covert channel would cause many similar data occurred repeatedly, the detection algorithm cluster based on density can be used to detect several kinds of the covert channels. Moreover, the detection approach cluster based on hierarchy and density is able to tackle of detection a noisy channel. Several detection tests were conducted, the detection results show that the algorithm can work well to distinguish the covert channel from normal network traffic even the noise level was about 20%.