Abstract: A first-order differential microphone array (FODMA) system with a steerable beamformer. The system includes a plurality (M) of microphones located on a substantially planar platform, the plurality of microphones comprising a first subset (M_1) of microphones and a second subset (M_2) of microphones, and a processing device, communicatively coupled to the plurality of microphones, configured to construct a first sub-beamformer based on the first sub-set (M_1) of microphones and a target beampattern at a steering angle ?, wherein the first sub-beamformer is characterized according to a first-order cosine (cardioid) first sub-beampattern, construct a second sub-beamformer based on the second sub-set (M_2) of the microphones and the target beampattern at the steering angle ?, wherein the second sub-beamformer is characterized according to a first-order sinusoidal (dipole) second sub-beampattern, and generate the steerable beamformer based on the first sub-beamformer and the second sub-beamformer.

Abstract: The present disclosure discloses a MEMS grating and a fabrication method. The MEMS grating includes a substrate layer, an insulation layer and a deformable layer. The deformable layer is made of a continuous conductive material, the insulation layer is distributed along transverse intervals on the substrate layer, and a cavity is formed between every two adjacent insulation layers. The deformable layer includes movable grating bars and fixed grating bars. The fixed grating bars are fixedly connected with the insulation layer, and the movable grating bars correspond to the cavities. A plurality of through holes are formed in the movable grating bars. During wet etching, the movable grating bars generate upwards buckling deformation, which increase an initial gap between the movable grating bars and a substrate. An adhesion effect caused by the wet etching is eliminated, which reduces permanent failures caused by the adhesion effect.

Abstract: Disclosed are a nickel-based superalloy formed by selective laser melting and a preparation method thereof. In the method, CrFeNb alloy powder is used as a grain refiner, and its element composition is within the composition range of a nickel-based superalloy powder to ensure that the prepared nickel-based superalloy has the same element composition with the original alloy; the grain size in the nickel-based superalloy could be refined by the addition of CrFeNb alloy powder, such that the anisotropic columnar grain structure in the alloy is transformed to equiaxed grain structure, thereby improving mechanical properties of the alloy.

Abstract: A multi-posture bedside writing pen includes a pen shell, a pen tip holder, a fiber rod and a fiber ink storage tube. The fiber ink storage tube is connected with the pen shell and located in the pen shell. The pen tip holder is connected with one end of the pen shell. The pen tip holder is axially provided with a through hole. The fiber rod is inserted into the through hole, one end of the fiber rod is exposed outside the pen tip holder, and an other end of the fiber rod is inserted into the fiber ink storage tube. A first gap is provided between the pen tip holder and the fiber ink storage tube.

Abstract: A preparation method of a flame-retardant ultrathin PEO-based solid electrolyte is disclosed. The method includes the following steps: preparing a CN support layer; synthesizing a flame retardant-loaded multifunctional filler: HNT@TMP; mixing and stirring PEO, LiTFSI, and HNT@TMP in a certain ratio in acetonitrile to obtain PEO-based solid electrolyte slurry; coating both sides of the CN support layer obtained in step S1 with the PEO-based solid electrolyte slurry obtained in step S3, and performing drying; and performing hot pressing to obtain a PEO-based solid electrolyte.

Abstract: Disclosed is a nighttime cooperative positioning method based on an unmanned aerial vehicle (UAV) group, falling within the technical field of aircraft navigation and positioning. According to the present disclosure, the cooperative visual positioning and the collision warning for UAVs are realized by means of light colors of the UAVs, respective two-dimensional turntable cameras and a communication topology network, without adding additional equipment and without relying on an external signal source, avoiding external interference. Compared with the positioning method in a conventional manner, in the present disclosure, the system is effectively simplified, and the cooperative positioning among the interiors of a UAV cluster can be realized relatively simply and at a low cost to maintain the formation of the UAV group.

Abstract: A space pen refill for an extravehicular activity, including a ball, a refill body, a fiber rod and a fiber ink-storage tube; the ball is rotatably connected in one end of the refill body, a segment of the ball is exposed outside the refill body, the fiber ink-storage tube is connected to an inside of the refill body, one end of the fiber rod is inserted into the fiber ink-storage tube, an other end of the fiber rod close to the ball is used to supply ink for the ball, an end face of an other end of the refill body is connected with first and second one-way valves, the first and second one-way valves are unidirectionally communicated with the inside and the outside of the refill body, and gas flow directions in the first and second one-way valves are opposite.

Abstract: The present disclosure relates to a method and system for determining transportation safety of pulverized coal. The method includes: acquiring coal particle data during transportation of pulverized coal, where the coal particle data is size data of a coal particle accumulation; determining a particle model of the coal particle accumulation during the transportation of the pulverized coal according to the size data; establishing a constitutive theoretical model to describe all flow regimes of a coal granular medium; numerically discretizing the constitutive theoretical model by using a numerical method to obtain discrete equations; calculating a movement process of the coal granular medium according to the discrete equations and the particle model of the coal granular medium to obtain a calculation result; plotting the calculation result by using post-processing software Tecplot to obtain relevant information of a coal particle flow; and determining whether the pulverized coal transportation process is safe.

Abstract: A system and method of generating binaural signals includes receiving, by a processing device, a sound signal including speech and noise components, and transforming, by the processing device using a deep neural network (DNN), the sound signal into a first signal and a second signal. The transforming further includes encoding, by an encoding layer of the DNN, the sound signal into a sound signal representation in a latent space, rendering, by a rendering layer of the DNN, the sound signal representation into a first signal representation and a second signal representation in the latent space, and decoding, by a decoding layer of the DNN, the first signal representation into the first signal and the second signal representation into the second signal.

Abstract: The disclosure relates to a video anomaly detection method based on human-machine cooperation, in which video frames and traditional descriptors of optical stream of an image are utilized as an input for auto-encoder neural network coding, and converted into a representation content of a hidden layer, and then the representation content of the hidden layer is decoded, reconstructed and output. The auto-encoder network is trained with normal samples. In a test stage, if an input is a normal sample, a final reconstructed error keeps high similarity with an input sample; on the contrary, if the input is an abnormal sample, the final reconstructed error deviates greatly from the input sample.

Abstract: A method for preparing an asymmetric wettable polyimide fiber-based photothermal aerogel is provided. The method includes the steps: uniformly mixing polyimide powder and a solvent, then, performing electrostatic spinning, and cutting an obtained fiber felt into pieces for later use; mixing the broken fibers, polyamic acid and tert-butyl alcohol, then, performing shearing to form a stable dispersion liquid for low-temperature directional freezing, and performing freeze-drying and high-temperature thermal imidization to obtain a polyimide fiber-based aerogel material; and soaking the above aerogel material in a hydrophilic monomer solution for a polymerization reaction, and then performing low-temperature directional freezing and freeze-drying to obtain a hydrophilic polyimide fiber-based aerogel.

Abstract: A device and a method for continuous temperature gradient heat treatment of a rod-shaped material are disclosed. The furnace body of the device includes an upper heating zone and a lower heating zone inside, which are independently controlled in temperature by means of an upper heating power supply and a lower heating power supply. Moreover, both the upper heating zone and the lower heating zone are closed heating zones. The closed heat insulation plates could prevent heat loss and ensure precise temperature control of the upper heating zone and the lower heating zone. In the device, a vacuum pumping equipment is included; an annular radiation screen is configured between the upper heating zone and the lower heating zone, and the rod-shaped material is not in contact with the annular radiation screen The rod-shaped material conducts one-dimensional heat transfer along the axial direction.

Abstract: A feature extraction deep neural network (DNN) may be trained based on the minimization of a loss function. A similarity function may be specified to calculate a similarity score for two representations of verbal utterances. A training data set comprising pairs of representations of utterances is received, wherein each one of the pairs of representations of utterances is associated with a corresponding a ground-truth label confirming whether the pair of represented utterances come from a same speaker or not. A respective similarity score may then be calculated for each one of the pairs of representations of utterances. Parameters associated with the DNN may then be updated based on minimizing a loss function associated with an area under a section of a receiver-operating-characteristic (ROC) curve for the similarity scores, wherein the ROC curve section is delimited between a low false positive rate (FPR) value and a high FPR value.

Abstract: A first-order differential microphone array (FODMA) with a steerable beamformer is constructed by specifying a target beampattern for the FODMA at a steering angle ? and then decomposing the target beampattern into a first sub-beampattern and a second sub-beampattern based on the steering angle ?. A first sub-beamformer and a second sub-beamformer are generated to each filter signals from microphones of the FODMA, wherein the first sub-beamformer is associated with the first sub-beampattern, and the second sub-beamformer is associated with the second sub-beampattern. The steerable beamformer is then generated based on the first sub-beamformer and the second sub-beamformer. The decomposing of the target beampattern into a first sub-beampattern and a second sub-beampattern includes dividing the target beampattern into a sum of a first-order cosine (cardioid) first sub-beampattern and a first-order sinusoidal (dipole) second sub-beampattern.

Abstract: The disclosure provides a eutectic ceramic thermal barrier material and a preparation method thereof, which relates to the field of composite materials. The present disclosure provides a eutectic ceramic thermal barrier material comprising a nickel-based superalloy substrate, an intermediate binding layer and a eutectic ceramic cladding layer stacked sequentially; the intermediate binding layer comprises a NiCoCrAlY binding layer; the eutectic ceramic cladding layer comprises an Al2O3/GdAlO3 binary eutectic ceramic coating or an Al2O3/GdAlO3/ZrO2 ternary eutectic ceramic coating. The eutectic ceramic thermal barrier material provided by the present disclosure has good high temperature resistance, good oxidation resistance and excellent mechanical properties.

Abstract: The present disclosure relates to the technical field of unmanned aerial vehicle (UAV) tests, and more particularly, to an electromagnetic release device for use in vertical falling tests of tri-rotor UAVs and including a mounting frame and multiple clamping and release modules arranged on the mounting frame. movable kits, which include a ferromagnetic plate matching and connected with the electromagnetic adsorption assembly, one end of the ferromagnetic plate is hinged with the electromagnet mounting frame, and the other end of the ferromagnetic plate is connected with the UAV connecting plate; The present disclosure uses electromagnetic control to accurately control the simultaneous opening of three clamping and release modules of a UAV, realizes the release and landing of the UAV in a horizontal status, and is characterized by simple structure and easy operation.

Abstract: This invention relates to a robust optimal design method for photovoltaic cells. Firstly, the deterministic optimal model is established, which is solved by Monte Carlo method to obtain the maximum output power value of optimization objective and its corresponding design variable value, and then the design variable value obtained from deterministic optimization is deemed as the initial point of the mean value of the robust optimal design variable. Later, the robust optimal model is solved by Monte Carlo method in order to obtain the mean value of design variable, and then appropriate materials and manufacturing techniques are selected for corresponding photovoltaic components according to the design variable obtained, so as to achieve the robust optimal design of photovoltaic cells. In fact, this invention improves the output stability and reliability of photovoltaic cells.

Abstract: A binaural beamformer comprising two beamforming filters may be communicatively coupled to a microphone array to generates two beamforming outputs, one for the left ear and the other for the right ear. The beamforming filters may be configured in such a way that they are orthogonal to each other to make white noise components in the binaural outputs substantially uncorrelated and desired signal components in the binaural outputs highly correlated. As a result, the human auditory system may better separate the desired signal from white noise and intelligibility of the desired signal may be improved.

Abstract: An Nth order linear differential microphone array (LDMA) with a steerable beamformer may be constructed by specifying a target beampattern for the LDMA at a steering angle ?. An Nth order polynomial associated with the target beampattern may then be generated. A relationship between the nulls of the polynomial and the steering angle ? is determined and then a value of one of the nulls is determined based on N?1 assigned values for the other nulls and the determined relationship between the nulls of the polynomial and the steering angle ?. The steerable beamformer may be generated based on the determined null value and the N?1 assigned null values. The N?1 assigned null values may be associated with the N?1 nulls of the polynomial that are of less than Nth order and the determined null value may be associated with the null of the polynomial that is of Nth order.

Abstract: An Nth order linear differential microphone array (LDMA) with a steerable beamformer may be constructed by specifying a target beampattern for the LDMA at a steering angle ?. An Nth order polynomial associated with the target beampattern may then be generated. A relationship between the nulls of the polynomial and the steering angle ? is determined and then a value of one of the nulls is determined based on N?1 assigned values for the other nulls and the determined relationship between the nulls of the polynomial and the steering angle ?. The steerable beamformer may be generated based on the determined null value and the N?1 assigned null values. The N?1 assigned null values may be associated with the N?1 nulls of the polynomial that are of less than Nth order and the determined null value may be associated with the null of the polynomial that is of Nth order.