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Compared with the traditional source radiated power estimation method, the matched-field source radiated power estimation method can obtain more accurate estimation results. However, its performance is greatly influenced by environmental mismatch. This paper defines the impact factor of environmental mismatch to quantify the impact of environmental mismatch on the acoustic transfer function and the matched-field source radiated power estimation method. It determines that the key to improve the robustness of environmental mismatch is to accurately estimate the acoustic transfer function. In the traditional matched-field source radiated power estimation method, the search domain of the acoustic transfer function is a distance-depth two-dimensional plane and does not contain the true acoustic transfer function when the environment is mismatched. Therefore, the estimation results of the acoustic transfer function are bound to deviate from those of the true acoustic transfer function. The paper expands the search domain dimension to a three-dimensional search domain that contains distance, depth and uncertain parameter sets. The true acoustic transfer function is included in the search domain. Thus the optimal alternative acoustic transfer function is equal to the true acoustic transfer function. The objective function for the three-dimensional search domain is constructed. The smaller the absolute value of the objective function, the less the acoustic transfer function estimation deviates from the true acoustic transfer function. The source radiated power is estimated more accurately when the alternative acoustic transfer function estimation corresponding to the minimum absolute value of the objective function. The simulation results verify the theoretical analysis results.

BackgroundIn recent years, the rapid advancement of nuclear energy and technology has led to the expanded utilization of special nuclear materials in more applications. In the pursuit of enhancing nuclear materials monitoring capability, extensive research has been dedicated to fast neutron multiplicity measurement systems based on liquid scintillation detector. However, these detectors are predominantly manufactured by foreign companies, such as Eljen and Saint-Gobain.PurposeThis study aims to evaluate the performance of a self-developed neutron detector based on EJ301 liquid scintillator.MethodsFirst of all, a 7.62 cm-diameter, 5.08 cm-thick liquid scintillator was applied to the development of neutron detector named EJ301-Z liquid scintillator detector, and 22Na and 60Co gamma sources were employed to calibrate this detector for establishing the relationship between incident particle energy and deposited energy. Subsequent tests on the neutron-gamma discrimination performance of the detector were conducted with a 252Cf neutron source, and figure-of-merit (FOM) values at different energy thresholds were calculated based on the charge comparison method. Then, comparison of the neutron-gamma discrimination performance of the detector with Eljen's EJ301 and Saint-Gobain's BC501A liquid scintillation detectors were conducted to evaluate the detector's performance relative to these commercially available models. Finally, the results obtained using the time-of-flight method were used to validate the results of the charge comparison method, providing an assessment of the absolute neutron-gamma discrimination performance of the liquid scintillator detector.ResultsThe experimental results show that, the EJ301-Z detect outperforms both Eljen EJ301 and Saint-Gobain BC501A detectors in terms of neutron-gamma discrimination, with an energy threshold of 150 keV, the rate of gamma mis-discrimination (RGMD) of EJ301-Z detector with the charge integration method is as low as 0.1‰.ConclusionsThe developed detector of this study demonstrates superior neutron-gamma discrimination performance compared to commercially available models from Eljen and Saint-Gobain.

Based on two meteor radars in mid‐latitudes of China, the mid‐latitude lower thermospheric neutral wind responses to the 2015 St. Patrick's Day great storm are investigated. The AE and PCN indices presented the similar quasi‐5‐hour oscillations during the storm. Interestingly, the analogous and close‐correlated storm‐time quasi‐5‐hour oscillations were also observed in both the meridional wind differences at 90–102 km derived from meteor radars. The meridional wind disturbances in the lower thermosphere also showed the extension toward the lower latitudes. It has been found that the enhanced equatorward wind disturbances at 250 km estimated by the Horizontal Wind Model‐14 and Fabry‐Perot Interferometer (FPI) emerged accordingly with the increases of AE and PCN with a time delay. And the enhancements of equatorward (poleward) wind disturbances at 250 km were accompanied by the increments of equatorward (poleward) wind disturbances at 94 km with a time lag of a few hours. It is thus suggested that the multiple intensified Joule heating events with quasi‐5‐hour time intervals were triggered by the successive substorm expansions during the storm. Then the Joule heating events led to the vertical wind and temperature disturbances in the mid‐latitude lower thermosphere via disturbing the thermospheric meridional circulation, which consequently induced the quasi‐5‐hour meridional wind disturbances therein. Plain Language Summary: The neutral temperature and global circulation in the middle and upper atmosphere can be strongly disturbed by the solar and geomagnetic activity. However, the effects of geomagnetic activity on the neutral winds in the mesosphere and lower thermosphere region at middle latitudes have not been fully understood. Using the neutral wind measurements from two meteor radars located at latitudes of 53.5°N and 40.3°N around 120°E meridian in China, we found that the meridional winds at different latitudes showed the prominent and similar disturbance patterns during the 2015 St. Patrick's Day geomagnetic storm. There exhibited the obvious quasi‐5‐hour oscillations in the meridional wind differences at 90–102 km derived from meteor radars. And such wind oscillations appeared to be analogous and close‐correlated to the quasi‐5‐hour oscillations in the AE and PCN indices. The possible contributors and physical processes responsible for such wind disturbances in the mid‐latitude lower thermosphere are discussed. This study is helpful to understand the influences of geomagnetic activity on the neutral winds in the mid‐latitude lower thermosphere region as well as the possible dynamic processes therein. Key Points: Storm‐time quasi‐5‐hour oscillations emerged in both the AE/PCN indices and the meridional winds in the mid‐latitude lower thermosphereThe increments of equatorward/poleward winds at 94 km exhibited the close correspondence and correlation to those at 250 km with a time lagThe successive Joule heating events led to the periodic meridional wind disturbances via disturbing thermospheric meridional circulation [ABSTRACT FROM AUTHOR]

The unusual stripe‐like scattered echoes were observed by the Hainan Coherent Scatter Phased Array Radar (HCOPAR) in the nigh of 9 Sep. 2017. There were parallel stripes with the interval of ∼33 min appearing from 12:57 to 17:50 UT. While the emergence of the scattered echoes, the Hainan Digisonde has observed the Spread‐F, and the Total Electron Content (TEC) maps recorded by the Global Navigation Satellite System (GNSS) in China show that there was no Equatorial Plasma Bubble (EPB), but the Medium‐Scale Traveling Ionospheric Disturbance (MSTID) traveled southwestward. The spatial and temporal distributions of the stripe‐like echoes and the MSTID show great consistency, indicating that the F‐region Field‐Aligned Irregularities were generated in the wave peaks and troughs of the MSTID. The MSTID has decayed greatly while reaching the HCOPAR, and the echo pattern is determined by the wave features of the MSTID. Key Points: Unusual stripe‐like echoes scattered from nighttime F‐region Field‐Aligned Irregularities were observed at low‐latitudesThe stripe‐like echo pattern exhibits a good correlation with the Medium‐Scale Traveling Ionospheric Disturbance (MSTID) observed in the Total Electron Content mapsThe scattered echoes were generated in wave troughs and peaks of the MSTID, and the echo pattern is determined by the wave features [ABSTRACT FROM AUTHOR]

The unusual daytime F-region Field-Aligned Irregularities (FAIs) were observed by the HCOPAR and the satellites at low latitudes on 13 June 2022. These irregularities survived from night-time to the following afternoon at 15:00 LT. During daytime, they appeared as fossil structures with low Doppler velocities and narrow spectral widths. These characteristics indicated that they drifted along the magnetic field lines without apparent zonal velocity to low latitudes. Combining the observations of the ICON satellite and the Hainan Digisonde, we derived the movement trails of these daytime irregularities. We attributed their generation to the rapid ascent of the F-layer due to the fluctuation of IMF Bz during the quiet geomagnetic conditions. Subsequently, the influence of the substorm on the low-latitude ionosphere was investigated and simulated. The substorm caused the intense Joule heating that enhanced the southward neutral winds, carrying the neutral compositional disturbances to low latitudes and resulting in a negative storm effect in Southeast Asia. The negative storm formed a low-density circumstance and slowed the dissipation of the daytime FAIs. These results may provide new insights into the generation of post-midnight irregularities and their relationship with daytime fossil structures. [ABSTRACT FROM AUTHOR]

Solar eclipse traveled across South China in the afternoon on 21 June 2020. Five ionosondes located from mid‐to low‐latitudes and on both north and south of the eclipse path were applied to investigate the ionospheric responses. Both the zonal and meridional ranges of the observation region have exceeded 1,000 km. All the five ionosondes had observed the Intermediate Descending Layers (IDLs) simultaneously just after the eclipse maximum and this is a very small probability event. During the solar eclipse, the multi‐hop echoes above the Es, the rising Es to 150 km altitude, the plasma flux from above F2‐layer were also observed and analyzed. The descending trend of the IDLs and the peak height of F2‐layer (hmF2) shows great consistency, indicating the close relationship between the eclipse induced plasma flux and the IDLs. The traces of gravity waves were also found in the IDLs and F‐layer. The plasma flux may carry the ions to valley region and the eclipse produced gravity waves were responsible for the formation of the IDLs. Key Points: Five ionosondes observed the intermediate descending layers simultaneously just after the solar eclipse maximumThe descending trend of the intermediate layers is very similar to that of the F2‐layer peak heightsPlasma flux and gravity waves associated with the solar eclipse are suggested to induce the intermediate descending layers [ABSTRACT FROM AUTHOR]

The correspondence between prescription and syndrome is the advantage and characteristic of traditional Chinese medicine (TCM) treatment. However, the pathogenesis of clinical diseases is complex and the condition is changeable, and the clinical application is difficult to achieve the maximum effect under the existing cognition of the correspondence between prescription and syndrome. In this paper, the five categories of physiological characteristics, pathological characteristics, constitution, syndrome, and disease of the longitudinal classification of "TCM state" are introduced into the correspondence of prescription and syndrome. Under the vertical perspective of "TCM state", the theoretical connotation of the correspondence between prescription and syndrome is interpreted as "correspondence between prescription and state", namely correspondence of "prescription-physiological characteristics", correspondence of "prescription-pathological characteristics", correspondence of "prescription-constitution", correspondence of "prescription-syndrome", and correspondence of "prescription-disease". It is hoped to accurately grasp the corresponding connotation of the correspondence between prescription and syndrome, in order to deepen the clinical thinking mode of TCM. [ABSTRACT FROM AUTHOR]

Introduction This study investigated the effect of combining hypoglossal-facial nerve “side”-to-side neurorrhaphy and electrical myostimulation in a rat model of facial palsy.

The tropopause region is crucial for the stratosphere‐troposphere exchange (STE) and acts as an indicator of climate change. Double tropopauses (DTs) act to increase the STE process but their driving mechanisms remain an open question. The present assessment offers for the first time the linkage between tropospheric gravity waves (GWs) and DT events by exploring a global data set of multi‐year radiosonde measurements. In the extratropics, the occurrence frequency of DT events keeps a remarkably consistent spatial‐temporal structure with GW total energy. Under the DT scenario, GW total energy has increased by 37.67% compared to single tropopause events. Based on a statistical assessment, the upward propagating GWs throughout the second tropopause region can probably raise Kelvin‐Helmholtz instability or turbulence, leading permanent irregularities in thermodynamic structure, and consequently, increasing the likelihood of DT. Plain Language Summary: Atmospheric disturbances above the troposphere are predominantly associated with waves generated in the troposphere. Among others, gravity waves (GWs) play major roles in transport of energy and momentum from the lower to the upper atmosphere. The double tropopause (DT) caused by irregular temperature changes is a common phenomenon in the lowermost stratosphere, which has an indicative significance for climate change. The upward propagating GWs sourced from the troposphere can probably alter the temperature variability in the tropopause region, and therefore, they are likely associated with the occurrence of DTs. By analyzing a large amount of global radiosonde data, simultaneous measurements of tropospheric GWs and irregularities in the tropopause enable us to argue that GWs sourced from troposphere could increase the likelihood of DTs. Key Points: A good level of agreement in spatial‐temporal variability has been identified between Double tropopause (DT) events and tropospheric gravity wave (GW) total energySubstantial tropospheric GW and Kelvin‐Helmholtz instability frequency enhancements in the tropopause region can be observed with DT phenomenaThe tropospheric GWs may increase the likelihood of DT events by introducing permanent localized irregularities or instabilities [ABSTRACT FROM AUTHOR]