Temperature retrieval of near space with the combined use of O(aΔ) and O(b∑ ) dayglow emissions under self-absorption effect correction.

Atmospheric temperature information in the near space is of great academic significance and engineering value to support the development and utilization of the near space. Based on the theory of O molecular dayglow spectroscopy and the mechanism of atmospheric radiative transfer, a method is proposed for the joint retrieval of temperature profiles in the near space using O(aΔ) and O(b∑ ) bands dayglow spectroscopy signal with the self-absorption effect. First, the temperature dependence of O(aΔ) and O(b∑ ) bands dayglow is investigated, and the influence of the self-absorption effect on the radiative transfer characteristics is analyzed in the limb-view mode.

Self-Regulation Phenomenon Emerged During Prolonged Fatigue Driving: An EEG Connectivity Study.

Driving fatigue is a common experience for most drivers and can reduce human cognition and judgment abilities. Previous studies have exhibited a phenomenon of the non-monotonically varying indicators (both behavioral and neurophysiological) for driving fatigue evaluation but paid little attention to this phenomenon. Herein, we propose a hypothesis that the non-monotonically varying phenomenon is caused by the self-regulation of brain activity, which is defined as the fatigue self-regulation (FSR) phenomenon.

μ-STAR: A novel framework for spatio-temporal M/EEG source imaging optimized by microstates.

Source imaging of Electroencephalography (EEG) and Magnetoencephalography (MEG) provides a noninvasive way of monitoring brain activities with high spatial and temporal resolution. In order to address this highly ill-posed problem, conventional source imaging models adopted spatio-temporal constraints that assume spatial stability of the source activities, neglecting the transient characteristics of M/EEG. In this work, a novel source imaging method μ-STAR that includes a microstate analysis and a spatio-temporal Bayesian model was introduced to address this problem.

A new Einstein coefficient method for mesopause-lower thermosphere atmosphere temperature retrieval under a non-local thermal equilibrium situation.

The mesopause-lower thermosphere (MLT) region is an important spatial region in the Earth's atmosphere, making it a valuable area to investigate the temperature variations. Kirchhoff's law fails with the altitude increase due to the non-local thermal equilibrium effect, resulting in an increase in the error of the method to retrieve the atmospheric temperature in the MLT region using the A-band spectral line intensity. In the non-LTE state, the temperature retrieval method based on the Einstein coefficients is proposed to retrieve atmospheric temperature in the 92-140 km height range using the airglow radiation intensity images obtained from the Michelson Interferometer for global high-resolution thermospheric imaging (MIGHTI) measurements.

Individualized Prediction of Task Performance Decline Using Pre-Task Resting-State Functional Connectivity.

As a common complaint in contemporary society, mental fatigue is a key element in the deterioration of the daily activities known as time-on-task (TOT) effect, making the prediction of fatigue-related performance decline exceedingly important. However, conventional group-level brain-behavioral correlation analysis has the limitation of generalizability to unseen individuals and fatigue prediction at individual-level is challenging due to the significant differences between individuals both in task performance efficiency and brain activities. Here, we introduced a cross-validated data-driven analysis framework to explore, for the first time, the feasibility of utilizing pre-task idiosyncratic resting-state functional connectivity (FC) on the prediction of fatigue-related task performance degradation at individual level.

Real-Time Monitoring of SO Emissions Using a UV Camera with Built-in NO and Aerosol Corrections.

Nitrogen dioxide (NO) absorption correction of the sulfur dioxide (SO) camera was demonstrated for the first time. The key to improving the measurement accuracy is to combine a differential optical absorption spectroscopy (DOAS) instrument with the SO camera for the real-time NO absorption correction and aerosol scattering correction. This method performs NO absorption correction by the correlation between the NO column density measurement of the DOAS and the NO optical depth of the corresponding channel from the SO camera at a narrow wavelength window around 310 and 310 nm.

Development of a self-calibration method for real-time monitoring of SO ship emissions with UV cameras.

Self-calibration of UV cameras was demonstrated for the first time. This novel method has the capability of real-time continuous calibration by using the raw images at 310 nm and 330 nm without changing the viewing direction or adding any additional equipment. The methodology was verified through simulations and experiments and demonstrated to be of greatly improved effectiveness and accuracy.

Real-time continuous calibration method for an ultraviolet camera.

The accuracy of cameras is significantly determined by the ability to obtain an accurate calibration. This work presents a real-time continuous calibration method for cameras with a moderate resolution spectrometer by taking realistic radiative transfer into account. The effectiveness and accuracy of the proposed method have been verified through simulations and experiments.

Simulation and application of the emission line OP of O(aΔ) dayglow near 1.27 μm for wind observations from limb-viewing satellites.

The O(aΔ) emission near 1.27 μm has relatively bright signal and extended altitude coverage and provides an important means to remotely sense the compositional structures and dynamical features of the upper atmosphere globally. In this paper, we report the simulation and application of O(aΔ) dayglow near 1.

2D visualization of hot gas based on a mid-infrared molecular Faraday imaging filter.

This Letter presents recent results on, to the best of our knowledge, the first experimental demonstration of a mid-infrared molecular Faraday imaging filter (MOFIF)-based camera for hot gas visualization. Gas-phase nitric oxide (NO) is used as the working material of the MOFIF due to the fact that NO is the typical representative of the paramagnetic species and plays an important role in the chemical and physical process of combustion reaction. The MOFIF transmission with comb-like transmittance spectrum is elaborately designed and matches well with the radiation spectrum of NO gas.

Development of an imaging gas correlation spectrometry based mid-infrared camera for two-dimensional mapping of CO in vehicle exhausts.

Real-time imaging of CO in vehicle exhaust was demonstrated using a gas correlation spectrometry based mid-infrared camera for the first time. The novel gas-correlation imaging technique is used to eliminate the spectral interferences from background radiation and other major combustion products, and reduce the influences of the optical jitter and temperature variations, thereby identifying and quantifying the gas. We take several spectral factors into account for the instrument design, concentration calibration and data evaluation, including atmospheric transmission, radiation interference, as well as the spectral response of infrared camera, filter and gas cell.

Demonstration of a mid-infrared NO molecular Faraday optical filter.

A molecular Faraday optical filter (MFOF) working in the mid-infrared region is realized for the first time. NO molecule was used as the working material of the MFOF for potential applications in atmospheric remote sensing and combustion diagnosis. We develop a complete theory to describe the performance of MFOF by taking both Zeeman absorption and Faraday rotation into account.

Temperature-insensitive laser frequency stabilization to molecular absorption edge using an acousto-optic modulator.

A temperature-insensitive edge laser frequency stabilization method with an acousto-optic modulator (AOM) was proposed and demonstrated both theoretically and experimentally in this Letter. In the method, in addition to the unshifted laser frequency, two other shifted frequencies were generated by the AOM. The intensity ratio of these two shifted frequencies was used to stabilize the laser.