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At present, the design and plan of the mine mobile communication system and the personnel and vehicle positioning system mainly depend on experience and field test. There are some problems such as heavy workload, difficult optimization of the layout of the communication base station and positioning substation and the antenna setting, etc. In order to promote the application of underground wireless transmission analysis methods in the design and plan of mine mobile communication system, personnel and vehicle positioning system, as well as the layout of the communication base station and positioning substation and the antenna setting, the application scope, advantage and disadvantages of different underground wireless transmission analysis methods are analyzed. ① Parabolic equation method has the advantages of simple algorithm and small computing memory resources. But it is not suitable for analyzing the influence of roadway undulation, support, longitudinal conductor and transverse conductor on wireless transmission attenuation in mines. ② The finite-difference time-domain method has a wide range of applications. But it requires a larger amount of computing memory resources. When analyzing the influence of roadway bending, undulation, irregular section shape and other factors on the wireless transmission attenuation in mines, the error is large. ③ The finite element method is the most widely used. The tetrahedral mesh can be used. Compared with the hexahedral mesh used in the finite difference time domain method, it can fit irregularly structured roadways better. But it requires the largest computing memory resources. The existing high-grade server memory capacity is difficult to meet the demand. It is suitable for small section, short distance, and low-frequency coal mine underground wireless transmission analysis. ④ The ray tracing method has the advantages of simple algorithm and minimum computing memory resources. But the application range is small. The ray tracing method is only suitable for analyzing the influence of factors such as high-frequency wireless working frequency, section shape, surrounding rock medium, and roadway bending on the wireless transmission attenuation of the mine. The ray tracing method cannot analyze the influence of factors such as different positions of an antenna on a roadway section, roadway branches, roadway undulation, supports, longitudinal conductor and transverse conductor on the wireless transmission attenuation of the mine. When analyzing the influence of low frequency band wireless operating frequency on the wireless transmission attenuation of the mine, the error is large. ⑤ The statistical analysis method has the advantage of simplicity and ease of use, but it requires a large amount of measured data. The coal mine underground roadway has a plurality of types, complex environment, branches, bends, and undulation. It has large measurement workload and low efficiency. It is difficult to measure the wireless transmission attenuation data under the conditions of different roadways and supports in the coal mine underground. It is difficult to analyze the wireless working frequency, the different positions of the antenna on the roadway section, the area and the shape of the roadway section, the bend of the roadway, the branch of the roadway, the undulation of the roadway, the surrounding rock medium, the supports, the longitudinal conductor and transverse conductor on wireless transmission attenuation of the mine.oadway, the surrounding rock medium, the supports, the longitudinal conductors, and transverse conductor on wireless transmission attenuation of the mine.

Rare earth elements (REE) are important raw materials for electronic products and green-energy technology and deep-sea sediment as an important potential source of REE mineral. It is of great scientific significance to understand the influence of REE in deep-sea sediments. In this paper, thirty sediments samples and eleven sediments samples were collected at the site SH3 and SH1 of Shenhu area, respectively. The trace elements, major elements, and different Fe-Mn minerals were analyzed to investigate the role of anaerobic oxidation of methane (AOM) in the enrichment of rare earth elements in the marine sediments. The result showed that the content of ∑REE/Ti increased at the top of sulfate and methane transition zone (SMTZ) at site SH1 and SH3. Combined with the analysis of different forms of ferromanganese minerals and the REE patterns, it is inferred that there is little influence of terrigenous input to the REE content. In contrary, the REE-rich carbonate phase and REE-rich Fe-Mn oxides (hydroxides) phase have important contribution of REE enrichment at the top of SMTZ. Meanwhile, the calculations of the quantitative relationship between the REE-rich carbonate phase and REE-rich Fe-Mn oxides (hydroxides) phase also confirm this conclusion. And the AOM caused the decrease of the REE-rich Fe-Mn oxides (hydroxides) phase and increase of the REE-rich carbonate phase. This is the potential explanation of ∑REE/Ti enrichment at the top of SMTZ. This study is of great scientific significance for the study of REE enrichment mechanism in the methane seeps and provided a new sight of REE enrichment mechanism in deep-sea sediments.

Large-scale conglomerate fan-delta aprons were typical deposits on the slope of Mahu Depression during the Early Triassic. Without outcrops, it is difficult to study the lithofacies only by examining the limited cores from the main oil-bearing interval of the Baikouquan Formation. Borehole electrical imaging log provides abundant high-resolution geologic information that is obtainable only from real rocks previously. Referring to the lithology and sedimentary structure of cores, a case study of fan-deltas in the Lower Triassic Baikouquan Formation of the Mahu Depression presents a methodology for interpreting the complicated lithofacies utilizing borehole electrical images. Eleven types of lithologies and five types of sedimentary structures are summarized in borehole electrical images. The sediments are fining upward from gravel to silt and clay in the Baikouquan Formation. Fine-pebbles and granules are the main deposits in T1b1 and T1b2, but sandstones, siltstones and mudstones are more developed in T1b3. The main sedimentary textures are massive beddings, cross beddings and scour-and-fill structures. Parallel and horizontal beddings are more developed in T1b3 relatively. On integrated analysis of the lithology and sedimentary structure, eight lithofacies from electrical images, referred to as image lithofacies, is established for the fan-deltas. Granules to coarse-pebbles within massive beddings, granules to coarse-pebbles within cross and parallel beddings, siltstones within horizontal and massive beddings are the most developed lithofacies respectively in T1b1, T1b2 and T1b3. It indicates a gradual rise of the lake level of Mahu depression during the Early Triassic, with the fan-delta aprons retrograding towards to the margin of the basin. Therefore, the borehole electrical imaging log compensate for the limitation of cores of the Baikouquan Formation, providing an effective new approach to interpret the lithofacies of fan-delta.

A simple method was developed for the determination of REEs, Zr, Hf, Th and U in ultramafic rocks by inductively coupled plasma‐mass spectrometry with a combination of RE and UTEVA extraction resins for their separation and pre‐concentration. Ultramafic rocks were digested with HNO3‐HF‐HClO4 and finally turned into 11 mol l−1 HCl solutions together with H3BO3 to remove insoluble fluorides. The removal of matrix elements was achieved during the loading procedure. Following this, REEs on RE resin, and Zr, Hf, Th and U on UTEVA resin were eluted with 10 ml of 0.24 mol l−1 HCl, with recoveries better than 94.4%. This method was validated using reference materials JP‐1, DTS‐2B, OKUM, UB‐N, MUH‐1 and DZΣ‐2, and the measurement results for target analytes were comparable to literature values, indicating its applicability to the determination of REEs, Zr, Hf, Th and U at ultra‐trace level in ultramafic rocks. [ABSTRACT FROM AUTHOR]

Multi-channel acquisition systems of brain neural signals can provide a powerful tool with a wide range of information for the clinical application of brain computer interfaces. High-throughput implantable systems are limited by size and power consumption, posing challenges to system design. To acquire more comprehensive neural signals and wirelessly transmit high-throughput brain neural signals, a FPGA-based acquisition system for multi-channel brain nerve signals has been developed. And the Bluetooth transmission with low-power technology are utilized. To wirelessly transmit large amount of data with limited Bluetooth bandwidth and improve the accuracy of neural signal decoding, an improved sharing run length encoding (SRLE) is proposed to compress the spike data of brain neural signal to improve the transmission efficiency of the system. The functional prototype has been developed, which consists of multi-channel data acquisition chips, FPGA main control module with the improved SRLE, a wireless data transmitter, a wireless data receiver and an upper computer. And the developed functional prototype was tested for spike detection of brain neural signal by animal experiments. From the animal experiments, it shows that the system can successfully collect and transmit brain nerve signals. And the improved SRLE algorithm has an excellent compression effect with the average compression rate of 5.94%, compared to the double run-length encoding, the FDR encoding, and the traditional run-length encoding. The developed system, incorporating the improved SRLE algorithm, is capable of wirelessly capturing spike signals with 1024 channels, thereby realizing the implantable systems of High-throughput brain neural signals. [ABSTRACT FROM AUTHOR]