The Solar Activity Monitor Network – SAMNet

The Solar Activity Magnetic Monitor (SAMM) Network (SAMNet) is a future UK-led international network of ground-based solar telescope stations. SAMNet, at its full capacity, will continuously monitor the Sun’s intensity, magnetic, and Doppler velocity fields at multiple heights in the solar atmosphere (from photosphere to upper chromosphere). Each SAMM sentinel will be equipped with a cluster of identical telescopes each with a different magneto-optical filter (MOFs) to take observations in K I, Na D, and Ca I spectral bands. A subset of SAMM stations will have white-light coronagraphs and emission line coronal spectropolarimeters. The objectives of SAMNet are to provide observational data for space weather research and forecast. The goal is to achieve an operationally sufficient lead time of e.g., flare warning of 2–8 h and provide many sought-after continuous synoptic maps (e.g., LoS magnetic and velocity fields, intensity) of the lower solar atmosphere with a spatial resolution limited only by seeing or diffraction limit, and with a cadence of 10 min. The individual SAMM sentinels will be connected to their master HQ hub where data received from all the slave stations will be automatically processed and flare warning issued up to 26 h in advance

Key technology research and engineering practice of speedy drivage with driving and bolting integration in soft surrounding rock

The technology and equipment of speedy drivage with driving and bolting integration of soft surrounding rock is an urgent need for safe and efficient mining and intelligent construction of coal mines. Based on the background of mining roadway engineering with such a swelling soft rock and jointed soft rock , the development status of speedy drivage technology of bolter miner at home and abroad is sorted out, and three problems faced by speedy drivage of bolter miner under soft surrounding rock conditions are analyzed, including: disturbance control of surrounding rock by full width cutting, timely and efficient permanent support of soft surrounding rock, temporary support of lateral wall in speedy drivage of soft surrounding rock. Five key technologies for speedy drivage of soft surrounding rock are proposed, including: ① Low disturbance cutting technology. It mainly includes elliptical full-width cutting drum, pick arrangement optimization, cutting dynamics optimization, etc. ② Timely support technology to reduce the distance between coal face and permanent support for roof or lateral wall. This technology is based on the integrated technology of excavation and anchoring. Through the research of the multi-driller integral sliding platform integrating double cylindrical guidance, multi-link lifting, supporting oil cylinder top and bottom support, and follow-up gangue curtain protection, the distance between coal face and permanent roof support of the bolter miner is reduced from 2.5 m to 1 m, and the empty side distance is reduced from 3.5 m to 1 m. ③ Multi-dimensional collaborative support technology of soft surrounding rock. Considering the space-time synergistic effect between the bolt and anchor cable support parameters and the synergistic effect between the support body and the surrounding rock, the low-density strong bolt support is used to control the roof at the head, and the enhanced permanent support is implemented simultaneously at the rear. ④ Drilling anchor integration technology. It mainly includes bolt structure and mechanical properties, anchoring agent materials and pumping. ⑤ Coal side spraying temporary support technology. It mainly includes fast reaction high elongation spraying material, high proportion precision spraying pumping, irregular coal wall surface adaptive trajectory control, mine explosion-proof high-precision mechanical arm, spraying material matching supply, etc. Based on the above content, a controllable operation empty top distance bolter miner was developed and underground tests were carried out.The test shows that the equipment effectively shortens the empty roof distance and empty side distance, realizes the ' controllable ' empty roof distance, adapts to the speedy drivage of soft surrounding rock roadway, and doubles the excavation efficiency

A Specific Combination Scheme for Modulation Identification of Mixed Modulation Signal

In this paper, we propose a specific combination scheme for modulation identification of mixed modulation signal based on decision theory and the tree classifier. In order to reduce the noise interference and improve the accuracy of modulation identification, we adopt the joint modulation signal characteristics with eigenvector made up of the number of subcarrier signal, envelope variance of mean normalization and the statistical value of subcarrier signal instantaneous amplitude distribution in identification of external modulation and internal modulation. Simulation results show that modulation identification ratio is close to 90 % when the SNR is 6 dB. And the proposed scheme outperforms the existing mixed modulation scheme

In-Situ Block Characterization of Jointed Rock Exposures Based on a 3D Point Cloud Model

The importance of in-situ rock block characterization has been realized for decades in rock mechanics and engineering, yet how to reliably measure and characterize the geometrical properties of blocks in varied forms of exposures and patterns of jointing is still a challenging task. Using a point cloud model (PCM) of rock exposures generated from remote sensing techniques, we developed a consistent and comprehensive method for rock block characterization that is composed of two different procedures and a block indicator system. A semi-automatic procedure towards the robust extraction of in-situ rock blocks created by the deterministic discontinuity network on rock exposures (PCM-DDN) was developed. A 3D stochastic discrete fracture network (DFN) simulation (PCM-SDS) procedure was built based on the statistically valid representation of the discontinuity network geometry. A multi-dimensional block indicator system, i.e., the block size, shape, orientation, and spatial distribution pattern for systematic and objective block characterization, was then established. The developed method was applied to a synthetic model of cardboard boxes and three different rock engineering scenarios, including a road cut slope from Spain and two open-pit mining slopes from China. Compared with existing empirical methods, the proposed procedures and the block indicator system are dependable and practically feasible, which can help enhance our understanding of block geometry characteristics in related applications

In-Situ Block Characterization of Jointed Rock Exposures Based on a 3D Point Cloud Model

The importance of in-situ rock block characterization has been realized for decades in rock mechanics and engineering, yet how to reliably measure and characterize the geometrical properties of blocks in varied forms of exposures and patterns of jointing is still a challenging task. Using a point cloud model (PCM) of rock exposures generated from remote sensing techniques, we developed a consistent and comprehensive method for rock block characterization that is composed of two different procedures and a block indicator system. A semi-automatic procedure towards the robust extraction of in-situ rock blocks created by the deterministic discontinuity network on rock exposures (PCM-DDN) was developed. A 3D stochastic discrete fracture network (DFN) simulation (PCM-SDS) procedure was built based on the statistically valid representation of the discontinuity network geometry. A multi-dimensional block indicator system, i.e., the block size, shape, orientation, and spatial distribution pattern for systematic and objective block characterization, was then established. The developed method was applied to a synthetic model of cardboard boxes and three different rock engineering scenarios, including a road cut slope from Spain and two open-pit mining slopes from China. Compared with existing empirical methods, the proposed procedures and the block indicator system are dependable and practically feasible, which can help enhance our understanding of block geometry characteristics in related applications

Special Structures of Sodium Layer Observed in the Daytime Over Beijing, China

In this paper the observation of sodium (Na) layer in mesosphere and lower thermosphere (MLT) region over complete diurnal cycles based on broadband Na lidar at Yanqing Station, Beijing, China (40.5°N,116°E ) was reported. Faraday filters with dual-channel design were used in the lidar receiving unit to suppress the strong background light in the daytime, which allow observation of Na layer with an acceptable signal-to-noise ratio (SNR) under sunlit condition. Several special structures of Na layer observed in the daytime was discussed. The simultaneous continuous observation of zonal wind by meteor radar was presented for comparison. These observation results can provide direct and reliable supports for the study of mesopause dynamics and solar effect on Na layer

Special Structures of Sodium Layer Observed in the Daytime Over Beijing, China

In this paper the observation of sodium (Na) layer in mesosphere and lower thermosphere (MLT) region over complete diurnal cycles based on broadband Na lidar at Yanqing Station, Beijing, China (40.5°N,116°E ) was reported. Faraday filters with dual-channel design were used in the lidar receiving unit to suppress the strong background light in the daytime, which allow observation of Na layer with an acceptable signal-to-noise ratio (SNR) under sunlit condition. Several special structures of Na layer observed in the daytime was discussed. The simultaneous continuous observation of zonal wind by meteor radar was presented for comparison. These observation results can provide direct and reliable supports for the study of mesopause dynamics and solar effect on Na layer