Abstract: The present disclosure provides a method for experimentally determining a critical sand-carrying gas velocity of a shale gas well. The method includes: collecting well structure and production data, calculating parameter ranges of a gas flow velocity and a liquid flow velocity; carrying out a physical simulation experiment of sand carrying in the shale gas well to obtain the sand holding capacity of the wellbore under different experimental conditions, and calculating a sand holding rate; by observing a change curve of the sand holding rate of the wellbore vs. the gas flow velocity, defining a turning point, and sensitively analyzing the influence of other experimental variables on the turning point, to calculate the critical sand-carrying production of the shale gas well under different conditions. Therefore, this calculation method is simple and applicable, and provides a theoretical basis for the optimization design of water drainage and gas production process.

Abstract: A native leaflet treatment system and method for treating native heart valve leaflets before heart valve repair or replacement procedure. The treatment system includes a delivery apparatus configured to enter the heart, and a native leaflet treatment device stored in the delivery apparatus in a compressed state. The treatment device includes a clamping structure, which is configured to retain at least a portion of the native leaflets in the deployed state. The treatment device is delivered into the heart using the delivery apparatus, and released near the native heart valve, where the treatment device expands and the clamping structure captures and holds the native leaflet, such that the native leaflets will no longer block blood flow. This improves the dynamics of the blood flow which facilitates subsequent surgical procedures (minimally-invasive surgery or open surgery) for heart valve repair or replacement.

Abstract: An air distribution mechanism and a corresponding cryogenic refrigerator are provided. The air distribution mechanism includes an air distribution valve (6) and a rotary valve (7), the air distribution valve (6) includes an air distribution valve main body (6a) and an air distribution valve seat (6b), an air distribution plane (6a3) that is on the air distribution valve main body (6a) and faces away from the air distribution valve seat (6b) protrudes relative to the air distribution valve seat (6b), the air distribution plane (6a3) is tightly attached to a switching plane (73) on the rotary valve (7), and the switching plane (73) protrudes from the rotary valve (7); the air distribution valve (6) is fixedly mounted in a mounting chamber of a cover (2), and the rotary valve (7) is rotatable around a principal rotation axis O of the rotary valve relative to the air distribution valve (6) to switch connection states of an air distribution side flow path and a switching side flow path.

Abstract: A self-pressure-relief air distribution mechanism includes an air distribution valve (6) where a rear face of the air distribution valve (6) is divided into a high-pressure face (66) and a low-pressure face (65), each hermetically separated by a third sealing ring (b3) that seals the air distribution valve (6) and a cover (2). A low-pressure passage (22) of the cover (2) can communicate with the rear face of the air distribution valve (6) via a pressure-relief hole (61), to guide a low-pressure airflow in the cover (2) to the rear face of the air distribution valve (6). A cryogenic refrigerator includes the self-pressure-relief air distribution mechanism. With the provision of the pressure-relief hole (61) and the third sealing ring (b3), the self-pressure-relief air distribution mechanism has a reduced pressure receiving area, thereby reducing a positive acting force and reducing wear.

Abstract: A non-contact facial blood pressure measurement method based on 3D CNN is disclosed, which belongs to the technical field of computer vision. The method includes the following steps. S110: collecting an actual face video sample and training a blood pressure prediction model based on face images using 3D CNN neural network. S120: obtaining a face video in real time through a HD camera. S130: recognizing face key points in the face video obtained in S120 through dlib face recognition model, selecting a face region of interest, and extracting face images from the region. S140: performing a wavelet transform operation on the face images extracted in S130 to remove noise. S150: inputting seven consecutive frames of the face images into the 3D CNN blood pressure prediction model trained in S110 to obtain a blood pressure value of the measured person. The disclosure realizes non-contact facial blood pressure measurement.

Abstract: The present invention discloses a food detection and identification method based on deep learning, which realizes food positioning and identification by a deep convolutional network. The method comprises: firstly, training a general multi target positioning network and a classification network by using food pictures; secondly, inputting the results of the positioning network into the classification network; finally, providing a classification result by the classification network. The method uses two deep convolutional networks with different functions to respectively detect and identify the food, which can effectively reduce the labeling cost of the food and improve the accuracy of positioning and identification.

Abstract: The present disclosure provides recombinant Pichia pastoris, a construction method thereof, and use thereof in the efficient preparation of 15?-D-ethylgonendione, and belongs to the technical field of fermentation engineering. In the present disclosure, with Pichia pastoris as a host, 15?-steroid hydroxylase and glucose-6-phosphate dehydrogenase (G6PD) are simultaneously induced in a manner of intracellular enzyme production for the first time, and the Pichia pastoris whole-cell induction and catalysis mode is used to achieve the conversion of D-ethylgonendione with high substrate loading and high conversion rate.

Abstract: The present invention discloses a food detection and identification method based on deep learning, which realizes food positioning and identification by a deep convolutional network. The method comprises: firstly, training a general multi target positioning network and a classification network by using food pictures; secondly, inputting the results of the positioning network into the classification network; finally, providing a classification result by the classification network. The method uses two deep convolutional networks with different functions to respectively detect and identify the, food, which can effectively reduce the labeling cost of the food and improve the accuracy of positioning and identification.

Abstract: A method for detecting back-drilled holes in a PCB and a PCB panel are provided. The method comprises: forming, on a metal layer of a first inner layer of a multi-layer PCB, metal rings according to positions of the back-drilled holes during a process of forming the PCB, wherein each of the formed metal rings has an outer diameter greater than an aperture of each of the back-drilled holes; forming, at positions corresponding to the positions of the back-drilled holes, metal holes extending through an outer layer of the PCB and the formed metal rings; forming two first detection holes electrically connected with the formed metal rings; forming the back-drilling holes on the PCB, which extend through and expand the metal holes; and detecting an electrical conduction between the two first detection holes so as to determine whether a position offset exists between the back-drilled holes and the metal holes.

Abstract: A method for detecting back-drilled holes in a PCB and a PCB panel are provided. The method comprises: forming, on a metal layer of a first inner layer of a multi-layer PCB, metal rings according to positions of the back-drilled holes during a process of forming the PCB, wherein each of the formed metal rings has an outer diameter greater than an aperture of each of the back-drilled holes; forming, at positions corresponding to the positions of the back-drilled holes, metal holes extending through an outer layer of the PCB and the formed metal rings; forming two first detection holes electrically connected with the formed metal rings; forming the back-drilling holes on the PCB, which extend through and expand the metal holes; and detecting an electrical conduction between the two first detection holes so as to determine whether a position offset exists between the back-drilled holes and the metal holes.

Abstract: A method of formation of integrated circuit devices includes forming a gate electrode stack over a portion of a semiconductor. The stack includes a gate dielectric layer with a gate electrode thereabove. Implant diatomic nitrogen and/or nitrogen atoms into the substrate aside from the stack at a maximum energy less than or equal to 10 keV for diatomic nitrogen and at a maximum energy less than or equal to 5 keV for atomic nitrogen at a temperature less than or equal to 1000° C. for a time of less than or equal to 30 minutes. Then form silicon oxide offset spacers on sidewalls of the stack. Form source/drain extension regions in the substrate aside from the offset spacers. Form nitride sidewall spacers on outer surfaces of the offset spacers over another portion of the nitrogen implanted layer. Then form source/drain regions in the substrate aside from the sidewall spacers.