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35 results about "Spectral signal-to-noise ratio" patented technology

In applied mathematics, the two-dimensional Spectral signal-to-noise ratio (SSNR) measures the normalised cross-correlation coefficient between several two-dimensional images over corresponding rings in Fourier space as a function of spatial frequency (Unser 1987). It is a multi-particle extension of the Fourier ring correlation (FRC), which is related to the Fourier shell correlation. The SSNR is a popular method for finding the resolution of a class average in cryo-electron microscopy.

Method for processing dynamic spectral data based on single-edge extraction

The invention discloses a method for processing dynamic spectral data based on single-edge extraction, and relates to the field of spectral analysis technology. The method comprises the following steps of: acquiring the all-band photoplethysmographic pulse wave; acquiring an all-band photoplethysmographic pulse wave template by using the all-band photoplethysmographic pulse wave and correcting the waveform of the photoplethysmographic pulse wave with each wavelength so as to eliminate the error introduced by the instability of the waveform of the photoplethysmographic pulse wave with each wavelength; removing single-edge dynamic spectrum comprising gross error by using the average effect of single-edge dynamic spectrums corresponding to a front edge and a rear edge of each pulse period according to a 3sigma rule; and superposing the remaining single-edge dynamic spectrums after the removal of the gross error to obtain dynamic spectral output. The method fully utilizes the acquired spectral data, improves the accuracy of the waveform of the photoplethysmographic pulse wave within each wavelength and each period, has higher accuracy, obviously improves the measurement speed, effectively improves the dynamic spectral signal-to-noise ratio and improves the accuracy of dynamic spectral method-based noninvasive blood component detection.
Owner:TIANJIN UNIV

Color filter tuning type window scanning optical spectrum imaging system and method

The invention relates to a tuning window-scanning spectral imaging system for a light filter and a tuning window-scanning spectral imaging method for the light filter, and belongs to the field of spectral imaging. The invention is to add a scanning system into a tuning static spectral imaging system for the light filter to make the tuning window-scanning spectral imaging system capable of performing dynamic window-scanning imaging. Moreover, the invention adopts a data acquisition processing system which is matched with the scanning system to make the tuning window-scanning spectral imaging system be capable of completing data processing in the mode of window scanning and output correct spectral cubical result. The invention has high utilization rate of light energy, high spectral resolution and flexible and adjustable service band of spectrums, has both the image signal-to-noise ratio and the spectrum signal-to-noise ratio easy to reach high level, can only be operated in interested wavebands, reduces the data quantity, increases the regulating range of the integral time, can improve the detection level of weak signals, and is suitable to be widely applied in the fields of agricultural production, resource exploration, environmental monitoring, disaster prevention and reduction, substance identification, public safety and the like.
Owner:BEIJING INSTITUTE OF TECHNOLOGYGY

Multi-mode fiber LIBS detector based on composite constraint enhanced spectrum

InactiveCN108362682AHigh sensitivityHigh sensitivity and high spectral signal-to-noise ratioAnalysis by thermal excitationFiberCollection system
The invention discloses a multi-mode fiber LIBS detector based on a composite constraint enhanced spectrum. The multi-mode fiber LIBS detector comprises a LIBS probe, a coupling collection system, anda control detection system, wherein the LIBS probe is composed of a fiber coupling head and a focusing chamber; the coupling collection system comprises a dichroscope, a fiber focusing device, and afiber collector; and the control detection system comprises a nanosecond laser, a spectrometer, a programmable pulse delay generator, an ICCD, and a computer. The multi-mode fiber is taken as a transmission medium, laser is focused to the surface of a to-be-measured sample to break induced plasma according to a convex lens imaging rule, and the element spectrum intensity is increased by a composite constraint enhanced plasma radiation method. The detector can realize simultaneous analysis of a plurality of elements, has the advantages of safe and reliable operation, high sensitivity, high measurement precision, high spectral signal-to-noise ratio, low element detecting limit, fast analysis speed, and high efficiency, realizes remote on-line monitoring, and can effectively satisfy the disadvantages of the traditional fiber LIBS detectors.
Owner:XI AN JIAOTONG UNIV

Infrared-modulated photoluminescence spectrum measuring method and apparatus based on step scan

The invention relates to a method and apparatus of infrared modulation photo-induced luminous spectrum based on step scan. The apparatus comprises a Fourier transform infrared spectrograph measuring system, a laser used as active light source, a lock-in amplifier which connects the Fourier transform infrared spectrograph detector and the circuit controlling plate and a circuit-breaker on the light path between the sample and the laser, so that it can transfer the constant active light into the modulated active light and feedback it in the reference end of the lock-in amplifier to control the lock-in.
Owner:SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI

Photo-modulated reflectance spectrum measuring method and apparatus based on step scan

ActiveCN1804583ALoosening of strict restrictionsEliminate Fourier frequenciesColor/spectral properties measurementsNon-linear opticsReflection spectroscopyLow-pass filter
The invention relates to a method and apparatus of photo-modulation reflection spectroscopy based on step scan. The apparatus comprises a Fourier transform infrared spectrograph measuring system, a laser used as pump light source, a lock-in amplifier and a low-pass filter which connect the Fourier transform infrared spectrograph detector and the circuit controlling plate, wherein the circuit-breaker on the light path between the sample and the laser can transfer the constant pump laser into the modulated laser and feedback it in the reference end of the lock-in amplifier to control the lock-in.
Owner:SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI

Indirect coupling conic fiber grating ultrasonic sensor

The invention relates to an indirect coupling conic fiber grating ultrasonic sensor. According to the indirect coupling conic fiber grating ultrasonic sensor, an upper end of a casing is provided with a sealing cover for processing a center hole, a sealing cover noise abatement pad is arranged between the sealing cover and the casing, a lower end of the casing is provided with a sound coupling cone, a sound coupling noise abatement pad is arranged between the sound coupling cone and the lower end of the casing, the top portion of the sound coupling cone is provided with a light guide fiber mounting hole through processing, one end of a light guide fiber is arranged in the light guide fiber mounting hole, the other end of the light guide fiber penetrates through the center hole of the sealing cover, the light guide fiber is provided with a grating, grating zone length of the grating is 1-10mm, and wavelength is 1540-1560nm. Based on tests, the sensor has excellent response performance, stability and sensitivity for 300KHz wave band ultrasonic signals, under the real-time acquisition mode, the spectrum signal to noise ratio is high, the ultrasonic signals reflected on upper and lower surfaces of organic glass can be intelligibly identified, the ultrasonic signals are suitable for dynamic scanning acquisition in an earthquake physics model, ultrasonic multi-layer imaging can be realized, and the sensor can be applied to the nondestructive structure test, oil and gas field physics model imaging, elastic wave speed modeling and biologic and medical technology fields.
Owner:NORTHWEST UNIV(CN)

600-700nm band fourier transform infrared photoluminescence spectrum measuring method and apparatus

The invention discloses a method and apparatus of 600-700nm wave range Fourier transform photo-induced luminous spectrum. The apparatus comprises a Fourier transform infrared spectrograph measuring system, a laser used as active light source, a lock-in amplifier which connects the Fourier transform infrared spectrograph detector and the circuit controlling plate and a circuit-breaker on the light path between the sample and the laser, so that it can transfer the constant active light into the modulated active light and feedback it in the reference end of the lock-in amplifier to control the lock-in.
Owner:SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI

Fiber LIBS detection system and method of optional double pulse modes

The invention relates to the technical field of laser diagnosis, in particular to a fiber LIBS detection system and method of optional double pulse modes. The system comprises an integrated fiber laser, a fiber LIBS probe, a control detection module and a fiber transmission module. Plasma emission spectrum signals enhanced by different degrees of double pulses are obtained by the system and the method, and the output laser time series of main pulse laser and sub pulse laser can be changed by changing the position of a visor and adjusting the position of a sub probe on a guide rail to switch four double pulse fiber LIBS detection modes for detecting a sample to be detected in multiple directions, thus obtaining obvious characteristic spectral lines for accurately analyzing the element typeand content of the sample to be detected. The system and the method can reduce the influence of matrix effect on detection, are high in repeatability, high in spectral signal-to-noise ratio, high in analysis speed, safe and reliable in measurement and high in element detection limit, and can be used for remote on-line monitoring.
Owner:XI AN JIAOTONG UNIV

Atmospheric pollution component inversion method based on ultraviolet-visible hyperspectrum of Gaofen-5 satellite

ActiveCN111859695AAccurately obtain column concentrationContinuous effective observationColor/spectral properties measurementsDesign optimisation/simulationAtmospheric sciencesAtmospheric pollution
The invention discloses an atmospheric pollution component inversion method based on the ultraviolet-visible hyperspectrum of a Gaofen-5 satellite, which can accurately obtain the column concentrationof atmospheric pollution components by performing inversion calculation on the ultraviolet-visible hyperspectrum of the Gaofen-5 satellite so as to realize large-range long-time continuous and effective observation of the atmospheric pollution components. Moreover, secondary spectrum calibration under the conditions of low spectrum signal-to-noise ratio and poor stability can be realized according to the characteristics and spectral characteristics of the Gaofen-5 instrument, so the inversion precision is improved.
Owner:UNIV OF SCI & TECH OF CHINA

Optical fiber LIBS detection system and method for underwater detection

The invention relates to an optical fiber LIBS (Laser-induced Breakdown Spectroscopy) detection system and a method for underwater detection. The optical fiber LIBS detection system comprises a laseroutput module, an underwater optical fiber LIBS probe and a control processing module. When the optical fiber LIBS detection system is used for detection, the underwater optical fiber LIBS probe is inflated through an air nozzle, and liquid below an optical window is discharged through a water discharge port, so that an air-like environment is created near the surface of a sample to be detected, thus an efficiency of laser breakdown induced plasma and a signal-to-background ratio of collected spectrum are greatly improved; various gas medium environments can be made in the underwater optical fiber LIBS probe according to actual requirements so as to meet medium environment requirements of laser detection for various elements; the optical fiber LIBS detection system can realize simultaneousanalysis of multiple elements, is safe and reliable in operation, high in repeatability, sensitivity and measurement accuracy, high in spectral signal-to-noise ratio, high in element detection limit,high in analysis speed and high in efficiency, can be used for remote online monitoring, and effectively solves the difficulty of underwater LIBS element detection.
Owner:SUZHOU NUCLEAR POWER RES INST +3

Statistics-based method for improving one-dimensional spectral signal-to-noise ratio of nuclear magnetic resonance

The invention discloses a statistics-based method for improving a one-dimensional spectral signal-to-noise ratio of nuclear magnetic resonance. On the basis of different statistic features of a noise region and a signal peak region of a nuclear magnetic resonance spectrogram, variable coefficients of the spectrogram at different positions are calculated to obtain a weighted array; and the weighted array is applied to spectrum data, so that the signal-to-noise ratio is improved.
Owner:WUHAN INST OF PHYSICS & MATHEMATICS CHINESE ACADEMY OF SCI +1

Wide band environment air infrared telemetering and monitoring system and method

The invention provides a wide band environment air infrared telemetering and monitoring system and method, wherein the system is mainly composed of an infrared monitor, a cloud head and an upper computer; the infrared monitor comprises an infrared window, a visible light window, a blackbody radiation calibration device, a front telescope, an interferometer, an infrared detector, a signal control and communication interface, an intelligent discriminator and a CCD camera. According to the invention, the system has the advantages of high spectral resolution and high luminous flux, can achieve theidentification and alarm of multi-component air, can fully utilize the built-in blackbody to carry out high-precision calibration, and can achieve on-line spectral calibration and radiation calibration requirements, the application advantage is obvious, particularly, a high level can be achieved in the aspect of spectral signal-to-noise ratio.
Owner:KUNMING INST OF PHYSICS

Infrared-modulated photoluminescence spectrum measuring method and apparatus based on step scan

The invention relates to a method and apparatus of infrared modulation photo-induced luminous spectrum based on step scan. The apparatus comprises a Fourier transform infrared spectrograph measuring system, a laser used as active light source, a lock-in amplifier which connects the Fourier transform infrared spectrograph detector and the circuit controlling plate and a circuit-breaker on the light path between the sample and the laser, so that it can transfer the constant active light into the modulated active light and feedback it in the reference end of the lock-in amplifier to control the lock-in.
Owner:SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI

Gas analyzer

The invention provides a gas analyzer. The gas analyzer is used for detecting and analyzing sulfur dioxide gas, and comprises an ultraviolet source used for emitting ultraviolet light beam, a collimating mirror, a gas absorption pool used for absorbing the ultraviolet light beam processed via collimation by the collimating mirror, a convergent mirror used for converging the ultraviolet light beam sent from the gas absorption pool, an ultraviolet photoelectric detector used for detecting the ultraviolet light beam converged via the convergent mirror, wherein the front surface of the collimating mirror is used for vertically receiving the ultraviolet light beam sent by the ultraviolet light beam, the collimating mirror is used for collimating the ultraviolet light beam, and an ultraviolet interference light filtering part is arranged on the light path between the ultraviolet source and the gas absorption pool. The gas analyzer possesses following advantages: luminous flux is large, spectrum signal to noise ratio is high, and cost is low. The gas analyzer is convenient for large scale popularization.
Owner:QINGDAO HAINA PHOTOELECTRICAL ENVIRONMENTAL PROTECTION

Spectral acquisition method for improving Raman spectral signal-to-noise ratio

The invention discloses a spectral acquisition method for improving a Raman spectral signal-to-noise ratio, which relates to a spectral acquisition method. The method comprises steps: 1) spectrometerarray background noise SA is acquired; 2) an integral time spectral signal set of a series of microcells is measured; and 3) differential projection and inverse differential calculation are carried out to acquire a sample true spectrum Ss. Through shortening cell integral time, the measurement times in a fixed measurement time are increased; and the more sampling times are beneficial to reduce SG,the occurrence probability of SE is reduced, and through eliminating an abnormal unit, the influences of the SE are eliminated. The reduced cells S are accumulated, an SR response with a high signal-to-noise ratio under a fixed time is obtained, the SG amplitude is proportional to the square root of the cumulative times, and the SG is suppressed. The Raman spectral signal-to-noise ratio can be improved, the linear response of an instrument is improved, the cost of the instrument is reduced, the acquisition efficiency and the operation flexibility are improved, the burr on a baseline is eliminated significantly, and the cost performance of the instrument is improved.
Owner:奥谱天成(厦门)光电有限公司

An active and passive dual-mode spectrometer

The invention discloses an active and passive dual-mode spectrometer, which is composed of two parts inside and outside a fuselage. Among them, there are two-in-one optical fiber, interface, slit and main controller outside the fuselage; the inside of the fuselage contains electric stage, active converging mirror, prism, active collimating mirror, active blazed grating, passive blazed grating, grating bracket, column Converging lens, linear variable filter, back-illuminated array detector, array drive circuit, passive converging mirror, passive collimating mirror, exit slit, shading screen, photomultiplier tube, motorized scanning table, scanning controller, working circuit. The beneficial effect of the present invention is that, by adopting ingenious electromechanical switching and grating area splitting, the internal structure of the spectrometer can be optimized, and the compactness and convenience of the system can be improved; the same spectrometer and the same optical fiber inlet can realize the composite detection of active and passive spectra, and improve the detection efficiency. Efficiency: According to the different characteristics of active and passive spectra, different designs are adopted at the sensor end to achieve targeted spectral detection, improve active spectral resolution and passive spectral signal-to-noise ratio.
Owner:SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI

Near infrared spectrum denoising method combining lifting wavelet and SG filtering

The invention relates to a near infrared spectrum denoising method combining lifting wavelet and SG filtering, and belongs to the technical field of near infrared spectrum signal preprocessing. The method includes: carrying out lifting wavelet decomposition on the noisy near infrared spectrum signal to obtain a multilayer wavelet coefficient; performing hard threshold de-noising on the high-frequency coefficient of each layer to obtain a de-noised wavelet coefficient; performing lifting wavelet inverse transformation reconstruction on the denoised wavelet coefficient to obtain a near infrared spectrum signal after preliminary denoising; and finally, carrying out Savitzky-Golay filtering (SG filtering) on the reconstructed near infrared spectrum signal, so as to obtain a final near infrared spectrum signal after denoising. The signal-to-noise ratio of the denoised near infrared spectrum and the original spectrum is high, and the root-mean-square error is low; the denoising effect is thorough, obvious signal distortion is avoided, and the near infrared spectrum analysis precision is improved.
Owner:SOUTHWEST UNIV

A device for improving the signal-to-noise ratio of blood absorption spectrum and its control method

The invention discloses a device for improving the signal to noise ratio of the blood absorption spectrum and a control method thereof. An oversleeve is connected respectively with an air pump and an air release valve through an air tube. The air pump pressurizes the sleeve through the air tube and deflates the sleeve through the air release valve. An import optical signal module and an export optical signal module are arranged at positions opposite to each other at the bottom of the nail of a finger. The import optical signal module is arranged upward and the export optical signal module is arranged downward. A data collecting module is respectively connected with the import optical signal module and the export optical signal module to collect a photoelectrical signal in a normal filling level and a photoelectrical signal in an enhanced filling level. The oversleeve is put on the upper end of the tested arm. The import optical signal module imports detection light and the export optical signal module exports an optical signal to obtain the difference of the photoelectrical signal and obtain the blood absorption spectrum with high signal to noise ratio according to the difference of the photoelectrical signal. The invention solves the problem of insufficient filling, obtains the ideal photoelectrical signal and improves the strength and the noise ratio of blood absorption spectrum.
Owner:TIANJIN UNIV

Active and passive dual-mode spectrum detection method

The invention discloses an active and passive dual-mode spectrum detection method. The method comprises three steps of active spectrum detection, passive spectrum detection and active and passive spectrum analysis. The method is advantaged in that ingenious electromechanical switching and grating area light splitting are adopted, optimization of an internal structure of a spectrometer is realized,and compactness and convenience of the system are improved; the same spectrometer and the same optical fiber inlet realize composite detection of active and passive spectrums, and detection efficiency is improved. Aiming at different active and passive spectral characteristics, different designs are adopted at a sensor end, so targeted spectral detection is realized, and an active spectral resolution and a passive spectral signal-to-noise ratio are improved.
Owner:SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI

Device for improving signal to noise ratio of blood absorption spectrum and control method thereof

The invention discloses a device for improving the signal to noise ratio of the blood absorption spectrum and a control method thereof. An oversleeve is connected respectively with an air pump and an air release valve through an air tube. The air pump pressurizes the sleeve through the air tube and deflates the sleeve through the air release valve. An import optical signal module and an export optical signal module are arranged at positions opposite to each other at the bottom of the nail of a finger. The import optical signal module is arranged upward and the export optical signal module is arranged downward. A data collecting module is respectively connected with the import optical signal module and the export optical signal module to collect a photoelectrical signal in a normal filling level and a photoelectrical signal in an enhanced filling level. The oversleeve is put on the upper end of the tested arm. The import optical signal module imports detection light and the export optical signal module exports an optical signal to obtain the difference of the photoelectrical signal and obtain the blood absorption spectrum with high signal to noise ratio according to the difference of the photoelectrical signal. The invention solves the problem of insufficient filling, obtains the ideal photoelectrical signal and improves the strength and the noise ratio of blood absorption spectrum.
Owner:TIANJIN UNIV

LIBS (Laser-induced Breakdown Spectroscopy) active and passive dual-mode spectrum detection system

The invention discloses an LIBS (Laser-induced Breakdown Spectroscopy) active and passive dual-mode spectrum detection system, which is mainly composed of a main controller, a dual-mode spectrometer,a wide-spectrum optical fiber, an interface, a slit, an LIBS pulse laser, a total reflection mirror, an ultraviolet detector, a Schmidt mirror, a distance measuring laser, a one-dimensional electric table, a secondary mirror, an electric controller, a main dichroic mirror, a primary mirror, a central lens and a rear dichroic mirror. The system has the beneficial effects that the optimization of the internal structure of a spectrometer is realized by adopting ingenious electromechanical switching and grating area light splitting, and the compactness and convenience of the system are improved; the composite detection of the LIBS active spectrum and the infrared passive spectrum is realized by the same spectrometer and the same optical fiber inlet, and the detection efficiency is improved; and different designs are adopted at a sensor end for different active and passive spectrum characteristics, so that targeted spectrum detection is realized, and the LIBS active spectrum resolution andthe infrared passive spectrum signal-to-noise ratio are improved.
Owner:SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI

Color filter tuning type window scanning optical spectrum imaging system and method

The invention relates to a tuning window-scanning spectral imaging system for a light filter and a tuning window-scanning spectral imaging method for the light filter, and belongs to the field of spectral imaging. The invention is to add a scanning system into a tuning static spectral imaging system for the light filter to make the tuning window-scanning spectral imaging system capable of performing dynamic window-scanning imaging. Moreover, the invention adopts a data acquisition processing system which is matched with the scanning system to make the tuning window-scanning spectral imaging system be capable of completing data processing in the mode of window scanning and output correct spectral cubical result. The invention has high utilization rate of light energy, high spectral resolution and flexible and adjustable service band of spectrums, has both the image signal-to-noise ratio and the spectrum signal-to-noise ratio easy to reach high level, can only be operated in interested wavebands, reduces the data quantity, increases the regulating range of the integral time, can improve the detection level of weak signals, and is suitable to be widely applied in the fields of agricultural production, resource exploration, environmental monitoring, disaster prevention and reduction, substance identification, public safety and the like.
Owner:BEIJING INSTITUTE OF TECHNOLOGYGY

A Raman spectrum signal-to-noise ratio evaluation method

The invention discloses a Raman spectrum signal-to-noise ratio evaluation method which comprises the following steps: (1) counting intervals of extreme values of spectrums of a CCD (Charge Coupled Device) spectrograph; (2) confirming CCD dark current noise; (3) calculating a signal-to-noise ratio. The invention discloses a simple, convenient and feasible signal-to-noise ratio evaluation method, the signal-to-noise ratio acquired by an equipment Raman spectrum can be estimated according to single spectrums, theories and experiments show that for a Raman spectrograph based on a CCD detector, when a sample and a characteristic peak are confirmed, a signal-to-noise ratio can be acquired on the basis of the method, Raman spectrum equipment of different configurations can be compared, and as a standard for controlling consistence of spectrum quality, the method has instruction significances for development of intelligent identification systems based on Raman spectrum techniques.
Owner:南京简智仪器设备有限公司

A photo-modulated reflectance spectrum measuring method and an apparatus based on step scanning

The invention relates to a method and apparatus of photo-modulation reflection spectroscopy based on step scan. The apparatus comprises a Fourier transform infrared spectrograph measuring system, a laser used as pump light source, a lock-in amplifier and a low-pass filter which connect the Fourier transform infrared spectrograph detector and the circuit controlling plate, wherein the circuit-breaker on the light path between the sample and the laser can transfer the constant pump laser into the modulated laser and feedback it in the reference end of the lock-in amplifier to control the lock-in.
Owner:SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI

A fiber optic libs detection system and method with optional double pulse mode

The invention relates to the technical field of laser diagnosis, in particular to a fiber LIBS detection system and method of optional double pulse modes. The system comprises an integrated fiber laser, a fiber LIBS probe, a control detection module and a fiber transmission module. Plasma emission spectrum signals enhanced by different degrees of double pulses are obtained by the system and the method, and the output laser time series of main pulse laser and sub pulse laser can be changed by changing the position of a visor and adjusting the position of a sub probe on a guide rail to switch four double pulse fiber LIBS detection modes for detecting a sample to be detected in multiple directions, thus obtaining obvious characteristic spectral lines for accurately analyzing the element typeand content of the sample to be detected. The system and the method can reduce the influence of matrix effect on detection, are high in repeatability, high in spectral signal-to-noise ratio, high in analysis speed, safe and reliable in measurement and high in element detection limit, and can be used for remote on-line monitoring.
Owner:XI AN JIAOTONG UNIV

Atmospheric Pollution Composition Retrieval Method Based on GF-5 Satellite UV-Vis Hyperspectral

ActiveCN111859695BAccurately obtain column concentrationContinuous effective observationDesign optimisation/simulationColor/spectral properties measurementsUltravioletSpectroscopy
The invention discloses an air pollution composition inversion method based on the ultraviolet-visible hyperspectrum of the Gaofen-5 satellite. Through the inversion calculation of the ultraviolet-visible hyperspectrum of the Gaofen-5 satellite, the column concentration of the air pollution composition can be accurately obtained , so as to achieve continuous and effective observation of air pollution components in a wide range and for a long time. In addition, according to the characteristics and spectral characteristics of the GF-5 instrument, the secondary calibration of the spectrum under the condition of low spectral signal-to-noise ratio and poor stability can be realized, thereby improving the inversion accuracy.
Owner:UNIV OF SCI & TECH OF CHINA

Non-contact type fiber ultrasonic sensor

The invention provides a non-contact type fiber ultrasonic sensor. The side wall height central plane of a fiber installation ring is provided at its left side with a fiber fixing tube in the radial direction. The fiber fixing tube is provided therein with a single-mode fiber and a fiber collimating mirror superposing the central line. The right end of the single-mode fiber is mounted at the left end face of the fiber collimating mirror; the inner side wall height central plane is provided at its right side with a reflection mirror. The reflection mirror forms an angle of 45 degrees with the horizontally incoming laser beams; the lower end of the fiber installation ring is provided with a hollow plug; and the upper end of the hollow plug inside the fiber installation ring is provided with a sensing diaphragm. According to the testing, the non-contact type fiber ultrasonic sensor of the invention responds well, stably and sensitively to the ultrasonic signals in 300KHz wave band. In a real-time acquisition mode, the spectral signal to noise ratio is high, making it suitable to detect the ultrasonic waves generated by partial discharge of a transformer and to acquire ultrasonic waves in real time.
Owner:NORTHWEST UNIV

An active and passive dual-mode spectral detection method

The invention discloses an active and passive dual-mode spectrum detection method, which comprises three steps of active spectrum detection, passive spectrum detection and active and passive spectrum analysis. The beneficial effect of the present invention is that the optimization of the internal structure of the spectrometer is realized by adopting ingenious electromechanical switching and grating area splitting, and the compactness and convenience of the system are improved; the same spectrometer and the same optical fiber inlet realize the composite detection of active and passive spectra, and improve the detection efficiency. Efficiency: According to the different characteristics of active and passive spectra, different designs are adopted at the sensor end to achieve targeted spectral detection, improve active spectral resolution and passive spectral signal-to-noise ratio.
Owner:SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI

Mask-based detection method for three-dimensional density map resolution of cryo-electron microscopy

The invention discloses a method for detecting resolution of a three-dimensional density picture of a cryo-electron microscopy based on a mask. The method is characterized in that the three-dimensional density picture reconstructed by the cryo-electron microscopy is segmented through a three-dimensional binary mask, radius power spectrums of an intramembranous particle structure part and an extramembranous background noise part of the three-dimensional density picture based on a three-dimensional shell of a Fourier space are respectively computed to obtain signal power and noise power of the three-dimensional density picture, so that an estimated value of the global resolution is obtained through a spectral signal to noise ratio based on the mask, which is obtained through calculation of the spectral signal to noise ratio, and a selected threshold, and thus evaluation of the reconstruction quality of the cryo-electron microscopy is implemented. According to the method, the resolution can be directly estimated from the three-dimensional density picture reconstructed by the cryo-electron microscopy, an algorithm is simple and practicable, and the method has a larger application space.
Owner:SHANGHAI JIAO TONG UNIV
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