Abstract: A channel prediction system and a channel prediction method for an OFDM wireless communication system include a standard echo state network and a two-layer adaptive elastic network. In the method, with respect to each subcarrier of a pilot OFDM symbol, an echo state network is trained by using frequency domain channel information of each subcarrier obtained by channel estimation. The trained echo state network may realize short-term prediction of the frequency domain channel information. To overcome a likely ill-conditioned solution of an output weight in an echo state network, the output weight in the echo state network is estimated by using a two-layer adaptive elastic network.

Abstract: The disclosure discloses a channel prediction method and system for a MIMO wireless communication system. The method includes the following steps: obtaining frequency domain channel information of each antenna pair of the MIMO wireless communication system through channel estimation; processing, by inverse Fourier transform, frequency domain channel information of each antenna pair to obtain information of each effective delay path of the MIMO wireless communication system; training the width learning system; utilizing the trained width learning system to predict each effective delay path of each antenna pair, so as to obtain the information of the next moment of each effective delay path of each antenna pair; after summarizing the information of the next moment of each effective delay path of each antenna pair obtained through prediction, the Fourier transform is utilized to convert the information into predicted frequency domain channel information.

Abstract: Provided is a method for estimating optimal efficiency point parameters in an axial-flow PAT power generation mode, including: I1, calculating an axial velocity of an optimal efficiency point; I2, calculating a flow rate of the optimal efficiency point; I3, calculating a theoretical hydraulic head; I4, calculating a frictional hydraulic head loss and a local hydraulic head loss of each segment; I5, calculating an output power of the optimal efficiency point; I6, calculating a hydraulic head of the optimal efficiency point in a power generation mode; and I7, calculating an optimal efficiency. Further provided is a method for estimating a performance curve in an axial-flow PAT power generation mode based on the above method for estimating an optimal efficiency point parameter, including: II1, calculating a normalized flow-hydraulic head curve; II2, calculating a normalized hydraulic head-output power curve; and II3, calculating a hydraulic head-efficiency curve.

Abstract: The disclosure provides a deep parallel fault diagnosis method and system for dissolved gas in transformer oil, which relate to the field of power transformer fault diagnosis. The deep parallel fault diagnosis method includes: collecting monitoring information of dissolved gas in each transformer substation and performing a normalizing processing on the data; using the dissolved gas in the oil to build feature parameters as the input of the LSTM diagnosis model, and performing image processing on the data as the input of the CNN diagnosis model; building the LSTM diagnosis model and the CNN diagnosis model, respectively, and using the data set to train and verify the diagnosis models according to the proportion; and using the DS evidence theory calculation to perform a deep parallel fusion of the outputs of the softmax layers of the two deep learning models.

Abstract: The invention discloses a device for preheating before welding and post-welding heat treatment of tank. The device includes a first roller, two electric heating belts, calipers, a thermostat, two positioners and hinges. Both of the electric heating belts are arranged around the tank and distributed on both sides of the welded seam. A number of calipers are provided on both sides of each electric heating belt, one end of each caliper can operatively clamp the side of the electric heating belt, another end of each caliper is rotatably connected to a first roller. The hinge is connected to the electric heating belt, and one end of the hinge away from the electric heating belt is in a fixed state. The heating temperature of the electric heating belt is controlled, thereby realizing preheating of the tank before welding, heat preservation during welding and post-welding heat treatment without transferring.

Abstract: The invention provides to a method and a system for fault diagnosis of a gearbox of a wind turbine generator based on stacked denoising autoencoders and relates to fault diagnosis. Signals obtained by pre-processing original vibration signals collected when the gearbox of the wind turbine generator is in different working states are used as training data. The training data are input into stacked denoising autoencoders. Meanwhile, a quantum-behaved particle swarm optimization algorithm is introduced to optimize the structure and parameters. Then, pre-processed test signals are input into the stacked denoising autoencoders that are trained to extract high-dimensionality fault features contained in the original vibration signals. Then, the extracted fault features are input into a least squares support vector machine to complete the fault diagnosis of the gearbox.

Abstract: The disclosure discloses an analog circuit fault feature extraction method and system based on an optimal wavelet basis function, and belongs to the field of electronic circuit engineering and computer vision, and the method comprises the steps of obtaining output signals of an analog circuit during different faults; sequentially applying wavelet transformation methods based on different wavelet basis functions to extract features of output signals; for each feature, calculating the center position of each fault, the distance from each fault data point to the center position, the farthest position of the fault data point and the average position of the fault data points; and determining an optimal wavelet basis function for analog circuit fault feature extraction according to a score discriminating method.

Abstract: A wireless channel monitoring and simulation device with multi-input multi-output (MIMO) is provided, which includes: a wireless channel monitor, configured to collect characteristic parameters of wireless channels in typical environments, and establish models based on the characteristic parameters; a model database, configured to store the characteristic parameter models and parameterize; an original signal, configured to input N different original signals; a wireless channel simulator, configured to simulate a typical channel environment according to the model database configuration, so that the original signal is the same as that in a real typical channel environment, and adopts a N-path output; an N-channel oscilloscope, configured to observe specific waveforms of N-path simulated signals; and a master computer software, configured to process, analyze, and store N-path output signals.

Abstract: This disclosure provides a PSR-PWM technique for high power active front-end inverters to damp a specific inter-harmonic that may cause relative sub-synchronous resonance in power system. Due to the strong interaction between wind power converters, photovoltaic converters, FACTS devices and HVDC transmission, low-frequency oscillations occur from a few Hz to dozens of Hz, or even high-frequency oscillations ranging from about 300-2000 Hz. Meanwhile, low-frequency oscillations ranging from 0.6 Hz to 7 Hz occur in the power supply systems of many electric locomotives. Even in the case of large-scale train outage, low-frequency oscillation will lead to abnormal locomotive dispatching system; in addition, the power grid voltage disturbance and flicker caused by a large number of high-power are furnaces and other nonlinear loads in the industrial field with a passband inter-harmonic frequency ranging from 0.05 Hz-90 Hz and so on are detected.

Abstract: A system for testing a Nakagami fading channel and a verification method thereof are provided. The testing system includes a signal generator, a Nakagami fading channel simulator, and a computer. The signal generator is used to output a sine wave signal whose frequency is f and transmit the sine wave signal to the Nakagami fading channel simulator and the computer. The Nakagami fading channel simulator is used to generate a Nakagami fading channel. The computer is used to perform data processing and analysis. In the verification method, time domain fading characteristics, first-order statistics characteristics, and second-order statistics characteristics of the Nakagami fading channel are respectively verified. Verifying the time domain fading characteristics is verifying a waveform fluctuation rate and a fluctuation range on a time domain under different Nakagami fading factors.

Abstract: A rotary joint, including: a hydraulic follow-up mechanism and a rotary transmission mechanism. The hydraulic follow-up mechanism includes a cylinder body, a valve sleeve, a valve core, a valve body, a left end cover and a right end cover. The rotary transmission mechanism includes a tray, a stabilizing ring, a follow-up disk, a torque transfer disk and a stable supporting wheel mechanism. The left end cover and the right end cover are arranged at the left and right ends of the cylinder body, respectively. The valve body is concentrically mounted in a cylindrical hollow chamber of the cylinder body. The output shaft at the right end of the valve body projects out of the right end cover. The right end of the valve core is provided with a valve core torque transfer shaft extending rightwards through the right end of the valve body.

Abstract: A thermoplastic polymer-based composite material and a preparation method thereof are provided. The thermoplastic polymer-based composite material is obtained by impregnating a reinforcing material with a mixture or oligomer of an epoxy resin, a bismaleimide resin, and a bifunctional amine (calculated based on active hydrogen), and then performing an in-situ polymerization. The thermoplastic polymer-based composite material has excellent impregnation effect, excellent secondary processing performance, relatively high heat resistance, excellent flame retardancy, and mechanical properties, and excellent comprehensive performance.

Abstract: A transformer failure diagnosis method and system based on an integrated deep belief network are provided. The disclosure relates to the fields of electronic circuit engineering and computer vision. The method includes the following: obtaining a plurality of vibration signals of transformers of various types exhibiting different failure types, retrieving a feature of each of the vibration signals, and establishing training data through the retrieved features; training a plurality of deep belief networks exhibiting different learning rates through the training data and obtaining a failure diagnosis correct rate of each of the deep belief networks; and keeping target deep belief networks corresponding to the failure diagnosis correct rates that satisfy requirements, building an integrated deep belief network through each of the target deep belief networks, and performing a failure diagnosis on the transformers through the integrated deep belief network.

Abstract: A thermoplastic polymer-based composite material and a preparation method thereof are provided. The thermoplastic polymer-based composite material is obtained by impregnating a reinforcing material with a mixture or an oligomer of an epoxy resin, a bisphenol A/F, and a catalyst and then performing an in-situ polymerization. The thermoplastic polymer-based composite material is less expensive to produce, has an optimal impregnation effect, excellent secondary processing performance, high heat resistance, desirable mechanical properties and excellent overall performance.

Abstract: The present invention relates to a polyvinyl alcohol/sodium alginate/hydroxyapatite composite fibrous membrane, and a preparation method and an application thereof. The preparation method of the composite fibrous membrane includes the following steps: firstly, reacting a diammonium hydrogen phosphate with a calcium nitrate to prepare a hydroxyapatite, and performing ultrasonic dispersion on the hydroxyapatite with a sodium alginate to form a stable hydroxyapatite suspension; separately preparing a sodium alginate solution of which the mass fraction is 2% and a polyvinyl alcohol solution of which the mass fraction is 18% using the above stable hydroxyapatite suspension; and finally, proportionally and uniformly mixing the two solutions, and performing electrospinning.

Abstract: The invention provides a whole-granulation steel slag pavement base course material for a heavy-load pavement, which is prepared by uniformly mixing dry materials with water. The dry materials include a binder and a steel slag aggregate. The percentages in total mass of the binder and the steel slag aggregate are as follows: the binder is 3.4% to 5.0%, and the steel slag aggregate is 95.0% to 96.6%. The binder is prepared by mixing cement with steel slag micropowder according to a certain proportion, wherein the mass percentages of the cement and the steel slag micropowder are as follows: the cement is 70% to 90%, and the steel slag micropowder is 10% to 30%. The water accounts for 5% to 6% of the total mass of the dry materials.

Abstract: A transformer failure identification and location diagnosis method based on a multi-stage transfer learning theory is provided. Simulation is set up first, a winding parameter of a transformer to be tested is calculated, and a winding equivalent circuit is accordingly built. Different failures are configured for the equivalent circuit, and simulation is performed to obtain a large number of sample data sets. A sweep frequency response test is performed on the transformer to be tested, and detection data sets are obtained. Initial network training is performed on simulation data sets by using the transfer learning method, and the detection data sets are further trained accordingly. A failure support matrix obtained through diagnosis is finally fused. The multi-stage transfer learning theory is provided by the disclosure.

Abstract: A titanium disulfide-sulfur (TiS2—S) composite particle contains a titanium disulfide (TiS2) substrate having solid elemental sulfur (S) disposed directly on a surface of the TiS2. The TiS2 substrate has a layered crystalline hexagonal structure of space group P-3 ml and includes at least 100 distinct layers. The TiS2 and S are present in the composite in a weight ratio (TiS2:S) of 20:80 to 50:50. Cathodes and batteries containing the composite particle, as well as related methods, are also disclosed.

Abstract: The disclosure relates to a method for simulating intraplate volcanism. A technical solution is: mixing 47-60 wt % of calcium oxide powder, 35 wt % of alumina powder and 5-18 wt % of silica powder uniformly to obtain a mixed powder; putting the mixed powder in a corundum crucible, placing the crucible in a high-temperature furnace provided with an observation window outside which an industrial camera with a depression angle of 30-45° is provided, heating to 1,500-1,900° C. at a rate of 1-30° C./min under an air atmosphere at a normal pressure, holding for 0.5-5 h; recording intraplate volcanism formed by upwelling of a melt of the mixed powder along an inner wall of the crucible during the holding with the industrial camera to obtain a simulated process of the intraplate volcanism.

Abstract: The disclosure provides a method for determining a slope slip plane with a gently-inclined soft interlayer, including: S1, determining a curve formed with a slip arc of a trailing edge tearing plane, a soft interlayer plane and a slip arc of a leading edge shear opening as a slope slip plane; S2, calculating a slip plane stability coefficient; S3, determination of a position of the gently-inclined soft interlayer plane: if the slip plane stability coefficient is less than 1 but close to 1, determining that the position of the slope slip plane is accurate; otherwise, moving the position of the soft interlayer plane and repeating steps S1 and S2, until the slip plane stability coefficient is less than 1 and close to 1. The method is simple, and has a high accuracy for determining a non-circular slip plane with a soft interlayer as a bottom slip plane.