Abstract: A vacuum-helium-leak-detection method based on a carbon-nanotube-based field-emission sensor that includes a carbon-nanotube-based cathode having a Raman amorphous peak ID/graphite peak IG ratio greater than 1.0. The method involves: setting a field-emission current at an initial, small emission current, recording an average of values of the field-emission current in a time period t, forming a sensing characteristic curve of the sensor, and performing fitting on the sensing characteristic curve so as to obtain an index curve; converting pressure values of helium gas into vacuum leak rates; and packaging the cathode into a vacuum chamber in a system to be detected, performing testing when a helium stream in the system to be detected reaches balance, obtaining an average of current variations in the time period t during the testing, and comparing the average with the index curve so as to determine a vacuum leak rate of the system to be detected.

Abstract: A confined silica/multi-walled carbon nanotube composite material, its preparation method, and application are provided. The preparation method includes the following steps: S1: dispersing multi-walled carbon nanotubes in a methyl-substituted benzene solvent and subjecting them to ultrasonication for 10 minutes at room temperature; S2: after the completion of ultrasonication, adding liquid silicon tetrachloride to the multi-walled carbon nanotube/xylene suspension and continuing ultrasonication for 10 minutes at room temperature; S3: heating the mixture in an oil bath to 145° C. and performing reflux; S4: after the reaction is complete, naturally cooling to room temperature, centrifuging, washing, and drying the obtained solid to obtain a dry sample, thereby obtaining the confined silica/multi-walled carbon nanotube composite material.

Abstract: An optical fiber multi-parameter sensing system and method are provided. The optical fiber multi-parameter sensing system comprises a light source, an optical circulator, a fiber-tip probe sensor and an optical spectrum analyzer, wherein the fiber-tip probe sensor can be placed into an analyte without changing the characteristics of the analyte. The variation of a bulk parameter that is a bulk refractive index of bulk environment around the fiber-tip probe sensor and a surface parameter which is a thickness of surface dielectric layer of the fiber-tip probe sensor can be determined simultaneously by monitoring the changing of resonance intensity and resonance wavelength of a single fiber-tip leaky mode resonance. The sensing system optionally configured such that multiple parameters in the analyte around the fiber-tip probe sensor can be obtained by detecting a single resonance peak.

Abstract: The present disclosure relates to a subtle cornea deformation identification method and device based on a pixel-level corneal biomechanical parameter, including the following steps: step 1, sampling and analyzing a dynamic video of corneal stress deformation in a historical database, and calculating pixel-level data; and step 2, configuring an ensemble classifier based on a sampling result and detecting a local change in corneal biomechanics, thus identifying a subtle cornea deformation. The present disclosure has high measurement accuracy and is capable of detecting a local subtle biomechanical change.

Abstract: Disclosed is a wireless detection device for quickly positioning a throw-fill stone falling depth and long-term settlement in blasting silt-squeezing construction, including a gravity ball and a signal receiving, processing and controlling system. The gravity ball is internally provided with test mechanisms, signal collecting and transmitting apparatuses and batteries. Also disclosed is a wireless detection method implemented using the above wireless detection device. The device and the method can detect the throw-fill stone falling depth and distribution situation in a blasting silt-squeezing construction process in real time, so that the effect evaluation and quality control of blasting silt-squeezing can be monitored in real time, the situation that the falling of throw-fill stones is incomplete can be acquired in time, monitoring data support can be provided for corresponding processing measures, and long-term settlement and other monitoring can be carried out.

Abstract: The present disclosure provides a two-dimensional motor piston pump, including a two-dimensional motor and a two-dimensional piston pump. The two-dimensional motor and the two-dimensional piston pump are nested with each other and arranged coaxially. The two-dimensional motor includes a stator and an outer rotor, and the outer rotor is coaxial with the stator and is sleeved outside the stator. The two-dimensional piston pump includes: a flow distribution mechanism including a flow distribution rotor and a pump body, a piston mechanism including a left cam and a right cam; a roller assembly including a roller and a roller shaft, and a pump housing, a left end cover, and a right end cover.

Abstract: A two-dimensional motor combination piston pump by combining two independent two-dimensional piston pumps into one structure is provided. The combination piston pump includes a two-dimensional motor and a two-dimensional piston pump. The outer rotator serves as the piston and the flow distribution mechanism of the two-dimensional piston pump. While operating, outer rotator rotates and moves axially.

Abstract: A high-speed machining tool made of a steel-bonded carbide and a method for preparing the same relate to the technical field of lathe tools made of steel-bonded carbides, and overcome the problems of traditional steel-bonded carbide lathe tools about low hardness and low toughness. The high-speed machining tool includes a skeleton, a main body, and a coating. The main body is consolidated by the skeleton from inside. The skeleton and the main body are both ringlike in shape. The main body has its outer surface covered by the coating. The high-speed machining tool is such made that the skeleton is hard and the main body is tough. The blade of the tool is hard and can transfer vibrations to the main body, thereby protecting the tool from brittle fractures and improving the overall performance of the tool.

Abstract: An optical fiber multi-parameter sensing system and method are provided. The optical fiber multi-parameter sensing system comprises a light source, an optical circulator, a fiber-tip probe sensor and an optical spectrum analyzer, wherein the fiber-tip probe sensor can be placed into an analyte without changing the characteristics of the analyte. The variation of a bulk parameter that is a bulk refractive index of bulk environment around the fiber-tip probe sensor and a surface parameter which is a thickness of surface dielectric layer of the fiber-tip probe sensor can be determined simultaneously by monitoring the changing of resonance intensity and resonance wavelength of a single fiber-tip leaky mode resonance. The sensing system optionally configured such that multiple parameters in the analyte around the fiber-tip probe sensor can be obtained by detecting a single resonance peak.

Abstract: A system synchronization method includes: connecting synchronization modules of a plurality of devices together through a synchronization bus. The synchronization modules include a signal generation module, a switch control module, a synchronization bus monitoring module, and a switch S1. A signal output terminal of the signal generation module is connected to a first terminal of the switch S1, and a timing overflow terminal of the signal generation module is connected to the switch control module configured to control the switch S1. The switch control module is connected to the synchronization bus monitoring module. A second terminal of the switch S1 is connected to the switch control module and the synchronization bus monitoring module. The system synchronization method has the advantages of simple structure, low cost, high reliability, and good practicability.

Abstract: A matching control method for mechanical impedance of a magnetostrictive precision transducer includes developing a three-layer neural network model corresponding to a Young's modulus of a Terfenol-D material; acquiring sample data to form a training sample set and a testing sample set; training the model using a Bayesian regularization training algorithm, and optimizing connection weights and thresholds among layers of the tested model, so as to obtain a final three-layer neural network model; based on the final model, building an inverse model of mechanical impedance of the magnetostrictive precision transducer; using a current level of impedance of a load as an input of the inverse model to obtain a bias magnetic field, and changing a level of the bias magnetic field by changing a bias current in an excitation coil of the transducer, thereby achieving adaptive matching between the mechanical impedance of the transducer and the impedance of the load.

Abstract: A digital-twin modeling method for an automated testing pipeline for circuit breakers involves acquiring a three-dimensional digitalized model of each mechanical installation in the testing pipeline; modeling hierarchy according to an actual production process and motion states; performing mesh optimization on the resulting model; designing movements of each said mechanical installation, so as to obtain mechanical movement tracks of the models; combining actual movement logic and cooperative relationship among the movements to edit the mechanical movement tracks of the models; and introducing motion control, so as to conduct motion simulation in a digital-twin scene, thereby implementing virtual movements synchronous with movements of the actual testing pipeline.

Abstract: The present disclosure discloses a monitoring device for internal deformation and fine particle loss of a railway subgrade, relating to the field of monitoring devices. The monitoring device includes an internal damage monitoring device arranged in a subgrade ballast layer. The internal damage monitoring device is connected to a resistance acquisition instrument through a wire. The resistance acquisition instrument is in wireless connection with a resistance signal receiver. The monitoring device for internal deformation and fine particle loss of a railway subgrade provided by the present disclosure can remotely realize real-time continuous monitoring of the deformation and fine particle loss inside the railway subgrade under a rail transit load, is economical and convenient, and has high practice value.

Abstract: A reaction of azacyclopropane derivative with elemental selenium and TMSCN to construct a selenium-containing heterocycle under metal-free and additive-free conditions is provided. The new strategy features no metal participation, no additive promotion, a wide substrate selection range and a good functional group compatibility, and provides an efficient and green approach to constructing a variety of selenium-containing heterocyclic compounds in a highly concise way.

Abstract: A method for assembling a dual-head pulling rod involves attaching pulling heads to two ends of a rod body through threaded connection using a system that includes a foundation, on which a rod dispensing device, an inclined guiding plate, a conveying flap, a head dispensing device, a head mounting unit, a clamping device, an assembling device and a V-shaped output channel are provided. The inclined guiding plate is inclined and uses its ramp to guide a rod body falling thereon. The conveying flap is swingable between an input position and an output position. The conveying flap at the input position receives the rod body coining from the inclined guiding plate and outputs the rod body to the clamping device.

Abstract: The present invention provides an online laser leveling detection method of a 3D printer. The method comprises: (1), arranging a bar-shaped triangular reflecting prism and a bar-shaped photoelectric receiver; (2), fixedly mounting a laser emitter and a plane mirror on the side face of a printer head; (3), with the aid of a detection laser beam, fine tuning the mounting azimuths of an X-axis guide rail, a Y-axis guide rail, and the printer head till the motion levelness of the printer head is adjusted to meet requirements of the design accuracy of the printer; (4), with the aid of the detection laser beam, fine tuning the mounting azimuth of a printing platform till the mounting levelness of the printing platform is adjusted to meet the requirements of the design accuracy of the printer; (5), starting the 3D printing program; (6), in the printing process, detecting in real time whether a nozzle of the printer head generates faults including material blockage, shortage, and breakage.

Abstract: A system synchronization method includes: connecting synchronization modules of a plurality of devices together through a synchronization bus. The synchronization modules include a signal generation module, a switch control module, a synchronization bus monitoring module, and a switch S1. A signal output terminal of the signal generation module is connected to a first terminal of the switch S1, and a timing overflow terminal of the signal generation module is connected to the switch control module configured to control the switch S1. The switch control module is connected to the synchronization bus monitoring module. A second terminal of the switch S1 is connected to the switch control module and the synchronization bus monitoring module. The system synchronization method has the advantages of simple structure, low cost, high reliability, and good practicability.

Abstract: The present disclosure discloses a monitoring device for internal deformation and fine particle loss of a railway subgrade, relating to the field of monitoring devices. The monitoring device includes an internal damage monitoring device arranged in a subgrade ballast layer. The internal damage monitoring device is connected to a resistance acquisition instrument through a wire. The resistance acquisition instrument is in wireless connection with a resistance signal receiver. The monitoring device for internal deformation and fine particle loss of a railway subgrade provided by the present disclosure can remotely realize real-time continuous monitoring of the deformation and fine particle loss inside the railway subgrade under a rail transit load, is economical and convenient, and has high practice value.

Abstract: A drilling device with a controllable femtosecond laser processing taper includes a femtosecond laser and a precision motion table. A support mechanism is provided along the central axis of the precision motion table, and a clamp is provided on the top of the support mechanism. The output end of the femtosecond laser is provided with a beam expander. The output end of the beam expander is provided with a reflection mirror. The output end of the reflection mirror is provided with a beam scanning module. The output end of the beam scanning module is provided with a semi-focusing mirror. The output end of the semi-focusing mirror is provided with a semi-transmissive reflection mirror arranged at 45 degrees. The reflection output end of the semi-transmissive reflection mirror is provided with a high-precision three-dimensional on-line monitoring module, and the transmission output end of the semi-transmissive reflection mirror faces the clamp.

Abstract: A method for synthesizing a chiral ?-hydroxy acid ester compound is disclosed. The method includes the steps of: using an aldehyde compound and a monoalkyl malonate as raw materials, using a metal and a chiral ligand as a catalyst to make the raw materials be directly and fully reacted in an organic solvent and form a reaction solution, and separating and purifying the reaction solution to obtain the highly stereoselective ?-hydroxy acid ester compound. The beneficial effects are mainly embodied in: 1. simple operation; 2. rapidly constructing a highly stereoselective ?-hydroxy acid ester skeleton structure molecule; 3. high reaction yield and good stereoselectivity. Therefore, the invention has high basic research significance, industrial production value and social economic benefit.