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In response to the lack of understanding of the rock burst prevention mechanism and the absence of evaluation methods for the prevention effect in surface hydraulic fracturing, this study focused on the hydraulic fracturing construction at No 401102 working face of the Mengcun Coal Mine. The research employed theoretical analysis, on-site monitoring, numerical simulation, and other methods to investigate the overlying strata structure and the movement form and process control mechanism of thick and hard key strata in the mining area after surface hydraulic fracturing. The study analyzed the characteristics of the dynamic load disturbance induced by the movement form and process changes of the thick and hard key strata and the characteristics of the influence of changes in the overlying rock structure on the degree of static load accumulation after the implementation of ground hydraulic fracturing in the mining space. It revealed the mechanism of ground hydraulic fracturing for preventing and controlling rock-bursts. Furthermore, the study proposed and applied a method for evaluating the effectiveness of surface hydraulic fracturing construction to prevent rock-bursts in coal mines, and the conclusions were as follows: ground hydraulic fracturing broke a complete thick hard rock formation into several fractured strata along the main fracture. The movement forms and processes of thick and hard rock strata was regulated to rotary or slippery movement, resulting in a reduction in the energy of mining-induced earthquakes and the equivalent additional disturbing stress in the working face. Additionally, the regulation of the overburden structure of the working face led to a change in the degree of static load concentration in the working face, thereby lowering the level of overburden pressure. Consequently, this reduced the scope of rock-burst hazard zones; Compared with the static load of the working face, the effect of ground hydraulic fracturing measures in regulating the dynamic load was more significant. Through theoretical calculations, the additional equivalent working face disturbance stress caused by the movement of the overlying rock after fracturing in the 401102 working face was 1.72 MPa, the peak strike support pressure was 42.26 MPa, and the influence range of the impact hazardous area was 12 m. These values were 76.0%, 8.5%, and 47.8% lower, respectively, than those observed with non-fracturing measures; In the fracturing particle flow numerical model, the fracturing main fissure provided a path for the development of the overlying rock structure, accelerated the extension of fissure development in the vicinity of the fractured layer position, and induced fractured strata to undergo slewing or sliding movement. Consequently, the height of the final overburden fissure development of the working face increased by 30 m, and the peak of the strike-supporting pressure at each measurement point was reduced by an average of 5.16 MPa; The evaluation parameter W was calculated as 0.62 for the rock burst prevention effect of the 401102 working face, indicating an excellent comprehensive evaluation of the fracturing rock burst prevention effect.

Abstract A new adaptive‐linear‐neuron‐ (ADALINE‐) based dead‐time compensation method is presented for permanent magnet synchronous motor (PMSM) drives. It is proposed to suppress the sixth current harmonics adaptively in the synchronous reference frame due to dead‐time effects. In order to extract the sixth current harmonics, two ADALINE‐based extractors are used without taking into account the electrical lead angle. An improved ADALINE algorithm is used to calculate compensation voltages, taking into account the phase shift of impedance. The proposed method is capable of operating not only at low speed but also at medium and rated speeds in contrast to the traditional compensation method of ADALINE only at low speed. The new method is effective in steady, load dynamic and speed dynamic states with no needs for any extra hardware to detect phase current polarity. The effectiveness of the proposed compensation method is verified on a 780 W PMSM drive through experiments.

In view of the frequent occurrence of rockburst in the coal pillars of high-stress roadways in deep underground coal mines in China, the types and mechanisms of rockburst in coal pillars are studied by means of field investigation, theoretical analysis, numerical simulation and engineering test. A new method of preventing rockburst by releasing energy and modifying the coal pillars of high-stress roadways is put forward. Based on the method proposed, a series of research work such as the principle research, technical system design and underground industrial test are carried out. Based on the main force source types of coal pillar rockburst in roadways, combined with many typical cases of rockburst, the coal pillar rockburst in roadways in China is divided into three types: basic stress superposition type, additional stress induced type and self-creep instability type. The mechanical models and engineering criteria of the occurrence mechanism of coal pillar rockburst in roadways are established and deduced respectively, which reveals its occurrence mechanism. In this paper, a method of preventing rockburst by combining fracturing with grouting in high-stress roadway in deep mine is proposed. The principle of preventing rockburst is embodied in two aspects: “energy release” and “modification”. The underground industrial test shows that the crack initiation pressure of elastic core coal is about 40 MPa, and the overall maximum fracturing width is 19.5 m. The field monitoring proves that the method proposed can reduce the energy accumulation level of roadway coal pillar and increase the overall impact threshold of roadway coal pillar. A complete technical system of coal pillar energy release modification and erosion prevention in high stress roadways of deep underground coal mines is designed, including the “evaluation-inspection-check” method of impact risk of isolated coal body, the energy release technology of elastic nuclear hydraulic fracturing and the whole grouting reinforcement modification technology. The “vibration-stress-displacement” three-field monitoring equipment for the elastic nuclear fracturing of coal pillars in roadways and the PS-Z-A/B type inorganic two-component quick-setting integral grouting modified material have been developed.

Introduction Hypoxaemia is a frequent complication associated with endoscopy conducted under intravenous sedation, highlighting the need for effective and practical interventions. This systematic review aims to evaluate the effectiveness of nasal mask oxygenation in reducing the incidence of hypoxaemia during endoscopy under intravenous sedation compared with the conventional oxygen supply.Methods and analysis This study strictly adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocol guidelines. PubMed, Embase, Cochrane Library, Web of Science and China National Knowledge Infrastructure databases will be electronically searched from their inception to May 2024 to identify randomised controlled trials comparing a nasal mask with conventional oxygen supply for endoscopy under intravenous sedation. The study selection, data extraction and quality assessment processes will be conducted independently by two reviewers. The risk of bias in the included studies will be assessed using the Cochrane Risk of Bias Tool for Randomized Trials, and the strength of evidence will be assessed using the Grading of Recommendations Assessment, Development, and Evaluation guidelines. The meta-analysis will be performed using STATA V.16.0, with effect sizes calculated using the standardised mean difference and 95% CI. Heterogeneity will be assessed using Cochran’s Q statistics, and inconsistency will be measured using I2 statistics. Potential sources of bias will also be evaluated.Ethics and dissemination The data used for this systematic review will be exclusively extracted from published studies. Additional ethical approval and informed consent are not required. This systematic review will be published in a peer-reviewed journal and will be presented at conferences and congresses.PROSPERO registration number CRD42024545231

In response to the challenging task of accurately identifying the main hazard-causing layer of overlying strata in the coal mine surface hydraulic fracturing construction, this study focuses on the industrial test of ground hydraulic fracturing at the 401102 working face of the Mengcun Coal Mine. The research is conducted using the methods of theoretical analysis, microseismic monitoring, and on-site investigation to reveal the dynamic disaster mechanism of mine earthquakes and rock bursts induced by the movement of thick and hard overlying strata in the coal mines. The relationship between the movement characteristics of thick and hard overlying strata based on a three-zone structure loading model of overlying strata and induced dynamic disasters is analyzed, and a prediction model for mining seismic energy and an estimation model for equivalent additional stress in mining areas based on the movement state of key layers are established. A coal mine identification technology for the main hazard-causing layer of overlying strata is proposed based on the K-means clustering algorithm and the elbow rule. The construction layer for hydraulic fracturing is determined, and an industrial test is carried out on-site. The effectiveness is verified based on the microseismic monitoring data and theoretical analysis results, leading to the following conclusions. In the Mengcun Coal Mine’s 401102 working face, both the key stratum responsible for rock bursts and mine seismic activities can be traced to the R9 key stratum of the Anding Group, situated 66 meters away from the coal seam. The primary fracturing movement of this critical stratum R9 imparts an equivalent supplementary disturbance stress value of 7.23 MPa, with the seismic energy liberated by this initial rupture motion quantifying to 6.08×105 J, thereby indicating a pronounced susceptibility towards catastrophic occurrences. After fracturing the key layer which induces mining earthquakes and rock bursts, the theoretical value of the mine earthquake energy is reduced by 94%, and the theoretical value of the equivalent disturbance stress of the working face is reduced by 76%. High-energy microseismic events above the working face with an energy of 5×103 J show a noticeable upward trend, with an upward movement of approximately 15 m. The frequency ratio of microseismic events with an energy level of 103 J or higher significantly decreases from 60.39% to 17.89%, and the maximum microseismic event energy decreases from 6.65×105 J to 9.75×103 J. The proportion of microseismic events with an energy level of 102 J and below significantly increases from 39.61% to 82.11%.

Abstract Background The elderly, especially those with physical disabilities, often encounter barriers that prevent them from accessing outdoor activities. Their perceptions of the convenience of accessing outdoor activities may be influenced by various factors including their health, the social context, and/or planned behavior. This study aimed to develop predictive models that identify the principal determinants of perceived convenience among this demographic, and it also examined the disparities observed between genders. Methods This was a cross-sectional survey of 1216 community-dwelling older people with physical disabilities in rural China. Grounded on the rehabilitation concepts and the theory of planned behavior, structural equation models integrated health and social behavior factors were constructed to predict perceived convenience of accessing outdoor activities. The standardized coefficients explained the contributions of various factors to the variance. Results The final structural models demonstrated good fit for both female and male participants. Perceptions of the convenience of accessing outdoor activities among both women and men were directly impacted by their physical functioning and their intention to participate, and indirectly by medical expenditure, subjective norms, pain, and role limitation in emotional interactions. Positive mental health was more influential for women, while men were more influenced by subjective norms. Conclusions Structural equation models have effectively predicted the self-reported convenience of accessing outdoor activities, underscoring the importance of functional and behavioral rehabilitation. Furthermore, gender-sensitive rehabilitation programs are advised to promote engagement in outdoor activities among elderly individuals with physical disabilities.

Abstract For high‐speed moving objects, drag reduction has been a prolonged major challenge. To address this problem, passive and negative strategies have been proposed in the preceding decades. The integration of creatures and nature has been continuously perfected during biological evolution. Unique structure characteristics, material properties, and special functions of marine organisms can provide inexhaustible inspirations to solve this intractable problem of drag reduction. Therefore, a simple and low‐cost laser ablation method was proposed. A multi‐scale and multi‐level riblet (MSLR) surface inspired by the denticles of the sharkskin was fabricated by controlling the density of the laser path and ablation times. The morphology and topographic features were characterised using an electron microscope and a scanning white‐light interfering profilometer. Then, the drag reduction capacity of the bionic riblet surface was measured in a circulating water tunnel. Finally, the mechanism of drag reduction was analysed by the computational fluid dynamics (CFD) method. The results show that the MSLR surface has a stable drag reduction capacity with an increase in Reynold (Re) number which was contributed by high‐low velocity stripes formed on the MSLR surface. This study can provide a reference for fabricating spatial riblets with efficient drag reduction at different values of Re and improving marine antifouling.

With the progress of science and technology, Artificial Intelligence (AI) technology has become one of the mainstream technologies in the current society, providing an important driving force for human development. Thereby, in order to improve the effect of animal feeding, using AI technology to improve animal feed has become a necessary measure. Based on this, this work designs to use Long Short-Term Memory (LSTM) technology to build an intelligent prediction model of metabolic energy, which provides a reference for animal feed proportioning design. This work also explores the comprehensive performance of the LSTM model through simulation evaluation. The model is evaluated with different nodes as the main indicators. The results show that compared with the models with 5 and 20 nodes, the model with 10 nodes has better performance, and the highest data calculation accuracy of the model is about 90%. Meanwhile, the highest fitting degree of the model designed is 98.2%, and the lowest is 96.2%. It suggests that the model designed can better predict metabolic energy. This work provides technical support for expanding the application scope of AI technology and contributes to the intelligence of animal feeding.

This paper investigates mechanical behaviours of sandstone during post-peak cyclic loading and unloading subjected to hydromechanical coupling effect, confirming the peak and residual strengths reduction laws of sandstone with water pressure, and revealing the influence of water pressure on the upper limit stress and deformation characteristics of sandstone during post-peak cyclic loading and unloading. Regarding the rock strength, the experimental study confirms that the peak strength σp and residual strength σr decrease as water pressure P increases. Especially, the normalized strength parameters σp/σpk and σr/σre was negatively and linearly correlated with the P/σ3. Moreover, the Hoek-Brown strength criterion can be applied to describe the relationship between effective peak strength and effective confining stress. During post-peak cyclic loading and unloading, both the upper limit stress σp(i) and crack damage threshold stress σcd(i) of each cycle tend to decrease with the increasing cycle number. A hysteresis loop exists among the loading and unloading stress–strain curves, indicating the unloading deformation modulus Eunload is larger than the loading deformation modulus Eload. Based on experimental results, a post-peak strength prediction model related to water pressure and plastic shear strain is established.

Abstract Introduction How to reconstruct the damaged fingertip is a clinical problem. Our team propose the theory of equivalent design and use the mini toenail flap pedicled with the hallux transverse artery and toe pulp vein transplantation technique to reconstruct Allen’s type II fingertip injury. Thus, we perform the retrospective study to evaluate the effects of this technique on fingertip injury. Materials and methods A retrospective analysis was performed on 56 patients admitted to our hospital from January 2015 to January 2020 who used equivalently designed miniature hallux toenail flaps for the plastic repair of fingertip damage. We recorded the size of the miniature hallux toenail flap, operation time, intraoperative blood loss, and complications and calculated the survival rate of the transplanted miniature hallux toenail flap. During routine follow-up after surgery, we recorded nail growth time and observed finger appearance. At the last time of follow-up, we recorded Semmes-Weinstein evaluating tactile sensation and Two-point discrimination testing (TPD). The efficacy was evaluated by Zook score evaluation. Results The size of the mini hallux toenail flap was 0.71 cm × 1.22 cm to 0.88 cm × 1.71 cm. The operation time was (3.54 ± 0.58) hours, the intraoperative blood loss was (20.66 ± 4.87) ml, and the survival rate of mini hallux toenail flaps was 100%. The postoperative follow-up time was (30.82 ± 11.21) months, and the total nail growth time was (9.68 ± 2.11) months. The average tactile sensation evaluated by the Semmes-Weinstein test was (0.32 ± 0.14) g, and the average TPD was (7.33 ± 1.02) mm. According to Zook score, the curative effect of fifty-six cases were all excellent or good with 100% excellent and good rate, and all patients had beautiful appearances and good function of damaged fingertips. Conclusions Based on the equivalent design theory, the mini hallux toenail flap pedicled with the hallux transverse artery and toe pulp vein transplantation technique is an effective method to reconstruct Allen’s type II fingertip injury with a beautiful appearance and good function. Type of study/level of evidence Therapeutic IV.

Sepsis remains a significant cause of mortality and morbidity worldwide, with limited effective treatment options. The T-cell immunoglobulin and mucin domain-containing molecule 3 (TIM-3) has emerged as a potential therapeutic target in various immune-related disorders. This narrative review aims to explore the role of TIM-3 in sepsis and evaluate its potential as a promising target for immunotherapy. We discuss the dynamic expression patterns of TIM-3 during sepsis and its involvement in regulating immune responses. Furthermore, we examine the preclinical studies investigating the regulation of TIM-3 signaling pathways in septic models, highlighting the potential therapeutic benefits and challenges associated with targeting TIM-3. Overall, this review emphasizes the importance of TIM-3 in sepsis pathogenesis and underscores the promising prospects of TIM-3-based immunotherapy as a potential strategy to combat this life-threatening condition.

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Due to its high infectivity, the pandemic has rapidly spread and become a global health crisis. Emerging evidence indicates that endothelial dysfunction may play a central role in the multiorgan injuries associated with COVID-19. Therefore, there is an urgent need to discover and validate novel therapeutic strategies targeting endothelial cells. PIEZO1, a mechanosensitive (MS) ion channel highly expressed in the blood vessels of various tissues, has garnered increasing attention for its potential involvement in the regulation of inflammation, thrombosis, and endothelial integrity. This review aims to provide a novel perspective on the potential role of PIEZO1 as a promising target for mitigating COVID-19-associated endothelial dysfunction.

The stress-loaded rockburst is a unique type of rockburst that occurs in some fully mechanized top-coal caving stopes with deep thick overburden, its occurrence mechanism is still unclear, leading to the failure to effective prevention and even serious accidents when the coal mine is faced with this type of rock burst. This study focuses on the stress-loaded rockburst that occurred in the 3304 fully mechanized top-coal caving face of the Zhaolou Coal Mine, Juye Coalfield, which lasted for 38 days and had a large range of impact warning (100 m ahead). Through material tests, theoretical analysis, numerical simulations, and field measurements, the study investigates the occurrence mechanism of stress-loaded rockburst in the fully mechanized top-coal caving stopes with deep thick overburden. The study proposes the spatial movement characteristics of overburden in the fully mechanized top-coal caving stopes with deep thick overburden through simulation tests and theoretical analysis. The contour expressions of collapse arch and pressure arch of thick overburden are derived based on the arching property and time-dependent loading property of thick overburden when the bearing bedrock is first broken. An estimation model for the transfer stress of overlying strata along the strike of the fully mechanized top-coal caving stopes with deep thick overburden is established. The mechanism of stress-loaded rockburst in the fully mechanized top-coal caving stopes with deep thick overburden is revealed through the study. When the bearing bedrock reaches the hanging limit and breaks and rotates, the thick overburden moves and sinks to form an earth pressure arch structure. The weight of the overlying thick overburden is transferred to the coal seam through the arch foot, resulting in a large range of coal seam stress in front of the coal wall that continues to rise in a short time, which can induce stress-loaded rockburst. The numerical simulation results show that after the bearing bedrock of fully mechanized top-coal caving stopes with deep thick overburden breaks, the thick overburden presents the movement characteristics of progressive breaking and collapse from the bottom to the top. The stope forms two pressure arches with the rock and soil contact surface as the boundary. The weight of the overburden pressure arches causes the high concentration of stress in the large range of coal seams in front of the coal wall. The field measurement shows that the dynamic load release level of the stope is low after the stress loading effect occurs, and the micro-earthquake concentration zone is fixed. The formation of the earth pressure arch will limit the rapid subsidence of the topsoil. The working face is located in the fulcrum area of the earth pressure arch for mining. When the working face pushes over the fulcrum loading area, the destruction of the earth pressure arch will lead to the overall large subsidence of the stope surface. The study proposes a prevention and control plan for the stress-loaded rockburst in the fully mechanized top-coal caving stopes with deep thick overburden, including underground ground joint monitoring and early warning, high-strength borehole weakening of surrounding rock, reinforcement of support system in the exposed area, and “monitoring and pressure relief” critical pushing speed control.

A novel 2000HS hot stamping steel was fabricated for automotive applications. Compared to the traditional 1500HS hot stamping steel, it showed an excellent combination of strength and plasticity, and the thickness of the oxide layer was dramatically reduced during the hot stamping process. The tensile experiment, scanning electron microscope (SEM), electron backscattered diffraction (EBSD), transmission electron microscope (TEM) and x-ray diffraction (XRD) characterization methods were employed, to clarify the best comprehensive mechanical properties of 2000HS steel. Experimental results indicated that the microstructure of Z740-A950-T170 consisted of lath martensite, large M23C6 precipitates, small (Nb, V) C precipitates and retained austenite (4∼6vol.%). The obtained best comprehensive mechanical properties of Z740-A950-T170 sample of the tensile strength was 2160 MPa, the yield strength was up to 1318 MPa, and the total elongation reached at 12%. The addition of Mo element inhibited the coarsening and lengthening of the precipitation. Large M23C6 precipitates (101.2 μm) and small (Nb, V) C precipitates (17.5 μm) played the role of pinning the dislocation and increased the yield strength. Regardless of any process, retained austenite was kept at room temperature (4–6 vol.%), which improving the strength and maintaining the total elongation by transformation induced plasticity (TRIP) effect. In addition, the oxidization layer thickness of the invented steel (12.4 μm) was thinner than that of the 1500HS (23.6 μm) after hot forming at 950 °C for 5 min. The significant reduction of oxidation was due to the high percent of Cr and Si contents within the designed steel, the formation of dense Cr and Si at the bottom of the oxide layer, which improving the antioxidant properties for studied steel.

This study determined the effects of seed structures on seed dormancy and tested methods to break dormancy in seeds of Urochloa hybrid cultivar ‘Mulato II’. Seeds stored for 10 months in indoor ambient conditions were studied to determine effects of seed structures on seed germination and their water permeability. Results showed that seed structures presented a barrier to water permeability. Removal of lemmas, puncturing the seed coat, seed structure removal and sulfuric acid immersion all reduced seed dormancy. Water and alcohol extracts from different parts of seeds inhibited seed germination of Brassica pekinensis seeds. There were 3 mechanisms responsible for seed dormancy; first, the mechanical barrier of seed structures, which excluded water and reduced gas exchange as well as restricting growth of the embryo; second, an endogenous germination inhibitor mainly found in lemmas; and third, water permeability of the seed coat (including pericarp and testa). The mechanical removal of lemmas and immersion in concentrated sulfuric acid reduced seed dormancy, although mechanical removal of the lemma alone was effective, convenient and safer.

In this study, a 780 MPa grade ferritic-bainitic dual-phase steel with excellent matching of strength-plasticity and formability was developed using thermomechanical control processing. Optical microscopy, Scanning electron microscopy, and Electron Backscatter Diffraction techniques were used to characterize the microstructure comprehensively, and the effects of coiling temperature on the microstructure, the strength-plasticity, and hole-expansion ratio of the test steels were thoroughly investigated. The results showed that the test steel had an excellent combination of ferrite and bainite at the coiling temperature of 520 °C, 23.7 and 76.3%, respectively, with a hole expansion ratio of 58.5 ± 2.8%. The uniformity of the microstructure was the key to obtaining a high expansion ratio in ferrite-bainite dual-phase steels. The test steels formed granular bainite at low-temperature coiling, while polygonal ferrite was promoted at high-temperature coiling. The effect of coiling temperature on grain size is small. Dislocations were redistributed during high-temperature coiling, resulting in a decrease in dislocation density. The higher elongation and hole expansion rate at higher coiling temperatures were attributed to increased polygonal ferrite content, reduced grain size, and enhanced TRIP effect. When coiling at low temperatures, the agglomeration of polygonal ferrite or granular bainite tends to result in a non-uniform distribution of the soft and hard phases of the matrix. At the same time, the strong texture parallel to the rolling direction has a significant difference in plasticity in different directions, leading to non-uniform deformation, which is liable to stress concentration, causing crack nucleation and extension in the hole expanding process, thus reducing the hole expansion performance.

Abstract With the development of individual wearable electronics, the requirements of self‐energy harvest devices from human skin or motion have increased. A thermal harvest device that receives thermal energy naturally existed in human skin is more attractive than a mechanical energy harvester that needs human motion or walking. Herein, a thermal‐chargeable supercapacitor (TCSC) is proposed, which can convert thermal energy into electrical energy and then store the energy only by occurring the temperature difference between the two ends of the TCSC. The all‐solid‐state g‐C3N4‐modified hydrogel electrolyte in the TCSC provides more free protons and energy for proton migration by the electrostatic interaction and hydrogen bond interaction between g‐C3N4 and the acid group. The 2D MOF@Ti3C2Tx MXene heterojunction electrodes with the advantages of large pore size, adjustable and abundant REDOX sites of MOFs, and high conductivity of Ti3C2Tx MXene also ensure the high performance of the TCSC. As a result, the assembled TCSC exhibits excellent ionic thermal‐voltage (55.68 mV), Seebeck coefficient (18.56 mV K−1), and energy exchange efficiency (3.4%) upon a temperature difference of 3 K, and successfully drives the pressure sensor work.

Due to the high data confidentiality, imperfect data acquisition technology and infrequent abnormal working conditions of oil and gas pipeline systems, it is impossible for the machine learning models to obtain the desired training effect with the available pipeline transportation data set. Herein, the energy consumption of pipeline transportation was analyzed based on a crude oil pipeline, and the power consumption of oil pump set thereof was simulated with Pipeline Studio TLNET to expand the data. Given the characteristics of simulation samples for pipeline transportation, such as no real value control, feature correlation, and high dimension, the Density-Based Spatial Clustering of Applications with Noise (DBSCAN algorithm) based on Mahalanobis distance was proposed to evaluate the reliability of simulation samples and identify the abnormal simulation samples. As shown by the examples, the fitting capability of the model can be improved after the simulation samples with the abnormal data eliminated are added to the training set. Generally, the research results provide a new idea for the generation and verification of simulation samples of the pipeline transportation data.

The nephrite jade deposits of different tectonic units in China exert significant commercial quality, which have attracted wide attention. However, these deposits have not been systematically summarized to date. Here, we investigate the major nephrite jade deposits in China to decipher their gemological and mineralogical characteristics, spatial-temporal distribution, and mineralization processes as well as to identify their geological settings and gemological properties, via integrating published geochronology, major and trace elements as well as H-O isotopes. The compiled data suggest that the major nephrite jade deposits in China can also be generally divided into green jade-type (GJ-type) and white jade-type (WJ-type) which covers different species, but most of them belong to the latter. The GJ-type nephrite deposits predominantly occur in ophiolite/ophiolitic mélange suites or are embedded into ultramafic serpentine jade orebodies. This type of nephrite jade mainly formed through the late auto-metamorphic metasomatism of serpentine or the spontaneous crystallization/precipitation along suture/shear zones that acted as pathways to migrate Ca-rich fluids during orogeny. In contrast, the orebodies of WJ-type nephrite jade are usually hosted at the contact zones between the dolomitic marbles and intermediate-felsic or mafic intrusive rocks, which were produced through metamorphism-metasomatism during post continent-continent collision, such as the Kunlun orogenic belt with about ∼1,300 km Hetian nephrite belt, and the eastern nephrite jade deposits along the Pacific Ocean. Our study highlights that the nephrite jade deposits in China originally formed during multiple tectonic stages related to the interactions between hydrothermal fluids and metamorphism under subduction accretion- and collision orogenesis-related settings. In addition, this study also provides insights into the genetic discrimination, mineral exploration, and occurrence characteristics of nephrite jade deposits as well as the evaluation and identification of nephrite jade quality.

Abstract In this study, a real‐time and dynamic time transfer method based on double‐differenced (DD) real‐time kinematic (RTK) mode is proposed. First, the method forms the DD observations of Global Navigation Satellite System (GNSS) to fix the DD ambiguity, and then, all of the fixed single‐differenced (SD) ambiguities are recovered while defining the SD ambiguity datum; finally, the method uses the SD observations to realise the time transfer by using the fixed SD ambiguities. Five different baseline links were used for the validations. The results demonstrated that the DD‐RTK method can be used for both kinematic positioning and precise time transfers, and it provides for much better accuracy and stability than the un‐differenced precise point positioning method because it is operated by the broadcast ephemeris, which is more convenient for real‐time applications.

In this paper, a low profile, dual-band dual-polarized patch antenna is proposed for antenna-filter function with a relatively low profile of 0.032 wavelength. A simple symmetric open/short-circuited stub (O/SCS) is proposed to excite a square radiating patch, and an additional resonant mode is generated except for the patch-mode. At the lower band, the proposed antenna works as a dual-polarized patch antenna. At the upper band, transmission characteristic is obtained between the two ports, and the antenna structure can be used as a bandpass filter. A $1\times 2$ array is also designed to validate its application potential in MIMO system. The two antennas can operate as radiators with high port isolation levels at the lower band. Meanwhile, at the upper band, the two antenna elements can act as one bandpass filter as the good transmission characteristic. In addition, a $2\times 2$ array is also developed meet dual-function demands in dual-polarized MIMO systems. The low profile, simple structures and excellent performances indicate that the proposed antenna can be a good candidate in future wireless communication applications with shared functions.

Since the accuracy of defect detection is strongly influenced by the data validity of pipeline magnetic flux leakage(MFL) inline detection, processing approaches for MFL failure data have been designed, based on the MFL failure signal characteristic analysis, to avoid, as far as possible, the influence of failure data. The approaches, such as threshold over-limit method, neighborhood difference threshold method, signal area, local zero-crossing rate, etc., were used for five types of failure data including over-limit failure, peak failure, continuous oversmoothing, single-channel data drift and sensor jitter, with the purpose of detection and rejection of failure data. With K-Nearest Neighbor(KNN) algorithm, the redundancy of the training set can be reduced by means of Support Vector Regression(SVR) algorithm, and the missing data interpolation method based on KNN and SVR was thus designed for missing data interpolation.The results demonstrate that, the data processing method for pipeline MFL failure is capable of accurately interpolating the missing MFL data in terms of different degrees of data missing, and considered to be of great reference to the failure data processing that frequently occurs in practical engineering.

Monitoring and providing warnings for coal mine rockburst disasters is a worldwide problem. Several rockburst accidents have occurred in a 1301 belt transport chute near a 1300 fully mechanized caving mine face. To address this issue, an empirical study of the occurrence mechanism of rockbursts in the adjacent area of the fully mechanized top-coal caving face was carried out. This paper mainly addresses the following issues: (1) based on microseismic monitoring technology, the distribution characteristics of the host-rock-supported pressure of the 1300 working face were measured, and the evolution and distribution of the deep-well caving working face host-rock-supported pressure were analyzed. It is revealed that the occurrence mechanism of rockburst in the adjacent area is actually caused by the evolution and superposition of the lateral abutment pressure of the 1300 stope, and the stress of the original rock along the 1301 belt transport down chute; (2) a theoretical calculation model of dynamic and static abutment pressure in longwall stope is built, and an example is tested. The results show that the peak position of lateral abutment pressure of the coal body outside the 1300 goaf is around 63 m, and the peak value of abutment pressure is around 47 MPa; (3) coal body stress monitoring, bolt dynamometer detection, and other means are compared and analyzed. At the same time, with the help of CT geophysical prospecting and drilling cutting measurements, it is concluded that the 1301 belt transport down chute is in the bearing pressure influence zone (superimposed zone), which further verifies the validity of microseismic analysis results and the accuracy of the above theoretical model. Based on this, the early warning system and prevention measures for rockburst based on microseismic monitoring are proposed. The engineering practice shows that the dynamic and static bearing pressure distribution and evolution law of the working face can be dynamically obtained by using microseismic technology, which provides a basis for the accurate prediction and treatment of rockbursts.

In coal mines, a reasonable design of the widths of coal pillars is critically important, particularly for rockburst mines. This is because the frequent occurrence of rock burst in coal mines often arises from the inappropriate widths of the coal pillars. To address this problem, we first review two recent incidents of rockburst occurring and thus present a theoretical calculation of lateral bearing pressure distribution in goaf of inclined thick coal seam to illuminate the occurrence mechanism of rockburst induced by inappropriate width of sectional coal pillars. Based on the mechanism model, we then propose a design criterion for sectional coal pillar widths in inclined thick coal seams that can effectively reduce the risk of the induced rock burst. Our theoretical calculations, field stress monitoring, numerical simulation and field investigation all demonstrate the validity of the proposed design criterion in preventing the induced rock burst and large deformation of surrounding rock. The results from this paper may be used as a theoretical guidance of sectional coal pillar designs in inclined thick coal seams.

For the problem of defect inversion in magnetic flux leakage technology, a fast, globally convergent particle swarm optimization algorithm based on the finite-element forward model is introduced as an inverse iterative algorithm in this paper. Two aspects of the traditional particle swarm optimization algorithm have been improved: self-adaptive inertia weight and speed updating strategy. For the inertia weight, it can be adaptively adjusted according to the particle position. The speed update strategy mainly uses the best experience positions of other particles in a randomly selected population to realize the algorithm’s learning. At the same time, the learning factor of the position variable is designed to change with the number of iteration steps. The particle with a good position is added to jump out of the local minimum and accelerate the optimization process. Through the comparison experiment, the improved particle swarm optimization algorithm has a faster convergence speed compared with other traditional particle swarm optimization algorithms. It is more difficult for it to fall into the local minimum value and it is more easily converted to a higher precision.

Accurate identification of ultrasonic signals can effectively improve the accuracy of a defect detection and inversion. Current methods, based on machine learning and deep learning have been able to classify signals with significant differences. However, the ultrasonic internal detection signal is interspersed with a large number of anomalous signals of an unknown origin and is affected by the time shift of echo features and noise interference, which leads to the low recognition accuracy of the ultrasonic internal detection signal, at this stage. To address the above problems, this paper proposes a two-stage ultrasonic signal recognition method, based on the envelope and local similarity features (TS-ES). In the first stage, a normal signal classification method, based on the envelope feature extraction and fusion is proposed to solve the problem of the low ultrasonic signal classification accuracy under the conditions of the echo feature time shift and noise interference. In the second stage, an abnormal signal detection method, based on the local similarity feature extraction and enhancement is proposed to solve the problem of detecting abnormal signals in ultrasound internal detection data. The experimental results show that the accuracy of the two-stage ultrasonic signal recognition method, based on the envelope and local similarity features (TS-ES) in this paper is 97.43%, and the abnormal signal detection accuracy and recall rate are as high as 99.7% and 97.81%.

For about a century, plant breeding has widely exploited the heterosis phenomenon–often considered as hybrid vigor–to increase agricultural productivity. The ensuing F1 hybrids can substantially outperform their progenitors due to heterozygous combinations that mitigate deleterious mutations occurring in each genome. However, only fragmented knowledge is available concerning the underlying genes and processes that foster heterosis. Although cotton is among the highly valued crops, its improvement programs that involve the exploitation of heterosis are still limited in terms of significant accomplishments to make it broadly applicable in different agro-ecological zones. Here, F1 hybrids were derived from mating a diverse Upland Cotton germplasm with commercially valuable cultivars in the Line × Tester fashion and evaluated across multiple environments for 10 measurable traits. These traits were dissected into five different heterosis types and specific combining ability (SCA). Subsequent genome-wide predictions along-with association analyses uncovered a set of 298 highly significant key single nucleotide polymorphisms (SNPs)/Quantitative Trait Nucleotides (QTNs) and 271 heterotic Quantitative Trait Nucleotides (hQTNs) related to agronomic and fiber quality traits. The integration of a genome wide association study with RNA-sequence analysis yielded 275 candidate genes in the vicinity of key SNPs/QTNs. Fiber micronaire (MIC) and lint percentage (LP) had the maximum number of associated genes, i.e., each with 45 related to QTNs/hQTNs. A total of 54 putative candidate genes were identified in association with HETEROSIS of quoted traits. The novel players in the heterosis mechanism highlighted in this study may prove to be scientifically and biologically important for cotton biologists, and for those breeders engaged in cotton fiber and yield improvement programs.

Abstract Background Heterosis, a multigenic complex trait extrapolated as sum total of many phenotypic features, is widely utilized phenomenon in agricultural crops for about a century. It is mainly focused on establishing vigorous cultivars with the fact that its deployment in crops necessitates the perspective of genomic impressions on prior selection for metric traits. In spite of extensive investigations, the actual mysterious genetic basis of heterosis is yet to unravel. Contemporary crop breeding is aimed at enhanced crop production overcoming former achievements. Leading cotton improvement programs remained handicapped to attain significant accomplishments. Results In mentioned context, a comprehensive project was designed involving a large collection of cotton accessions including 284 lines, 5 testers along with their respective F1 hybrids derived from Line × Tester mating design were evaluated under 10 diverse environments. Heterosis, GCA and SCA were estimated from morphological and fiber quality traits by L × T analysis. For the exploration of elite marker alleles related to heterosis and to provide the material carrying such multiple alleles the mentioned three dependent variables along with trait phenotype values were executed for association study aided by microsatellites in mixed linear model based on population structure and linkage disequilibrium analysis. Highly significant 46 microsatellites were discovered in association with the fiber and yield related traits under study. It was observed that two-thirds of the highly significant associated microsatellites related to fiber quality were distributed on D sub-genome, including some with pleiotropic effect. Newly discovered 32 hQTLs related to fiber quality traits are one of prominent findings from current study. A set of 96 exclusively favorable alleles were discovered and C tester (A971Bt) posited a major contributor of these alleles primarily associated with fiber quality. Conclusions Hence, to uncover hidden facts lying within heterosis phenomenon, discovery of additional hQTLs is required to improve fibre quality. To grab prominent improvement in influenced fiber quality and yield traits, we suggest the A971 Bt cotton cultivar as fundamental element in advance breeding programs as a parent of choice.

The optical, color, electrical, and thermal properties of an LED devices are highly dependent on one another. The luminous flux variation and correlated color temperature (CCT) shifting of white LED sources is attributed to luminous efficacy and emission spectrum shifting with the electrical power and heat-dissipation power. An analysis model that includes the luminous flux, CCT, electrical power, and junction temperature of the white LED sources with bilevel driver is proposed in this paper. The proposed model can descript that the stablized luminous flux and CCT of the white LED system with bilevel driver is a result of the complex interactions among the given electrical power of bilevel, duty cycle, thermal resistances, junction temperature, and the physical parameters of the LED sources. Reduction variation of CCT and luminous flux of the white LED device with bilevel driver over a dimming range has been practically achieved. The proposed method can be easily adopted for improving the CCT and luminous flux stabilization of the white LED device with a bilevel driver.

Self-organizing feature map (SOM) neural network is a kind of competitive neural network with unsupervised learning. It has the strong abilities of self-organization and self-learning. However, the classification accuracy of SOM neural network may decrease when the features of tested object are not obvious. In this paper, the particle swarm optimization (PSO) algorithm is used to optimize the weight values of SOM network. Three indexes, i.e., intra-class density, standard deviation and sample difference, are used to judge the weight value, which can improve the classification accuracy of the SOM network. PSO–SOM network is applied to the detection of series arc fault in electrical circuits and compared with conventional SOM network and learning vector quantization (LVQ) network. The detection accuracy of the PSO–SOM network is 95%, which is higher than conventional SOM network and LVQ network.

In deep mines, a reasonable design of the widths of isolated coal pillars (ICPs) is critically important, particularly for hard-strata mines. This is because the frequent occurrence of mine seismicity (MS) and rockburst in deep mines often arises from the inappropriate widths of the remnant ICPs. To address this problem, this paper takes the ICP of Yingpanhao Coal Mine in Inner Mongolia in China as the engineering case study and then presents a mechanical model to illuminate the occurrence mechanism of MS induced by the mining on both sides of ICPs. The results indicate that, after the mining on both sides of ICPs, the ICPs will produce a vertical compressive deformation, and the overlying high main key stratum (MKS) will experience a flexure deformation. When the limited deflection of MKS is less than the compression of ICPs, the MKS will be fractured, and the released energy may lead to MS. Based on the mechanism model, a design criterion is proposed for ICP widths; this criterion can effectively reduce the risk of the induced rockburst and MS. Then the occurrence mechanism of MS and the design basis for ICP width are verified by numerical simulation and field microseismic monitoring. The results in this paper may be used as a theoretical guidance for rational ICP design in deep mines and may help mitigate the risk of rockburst and MS from early mining stages.

In this study, a real-time earthquake monitoring system based on the integration of single-frequency global navigation satellite system (GNSS) and strong motion (SM) observations was developed. This high-precision integrated system can provide full-frequency monitoring information, and it makes full use of SM data to quickly and accurately determine the vibration window for initial baseline shift correction. High-precision displacement data obtained from GNSS epoch-differenced velocity estimation are used to constrain the SM’s low-frequency baseline shift. Hence, full-frequency monitoring information (displacement, velocity, and acceleration) can be provided in real-time. Three different datasets were used for validation and the results confirm that the proposed system can be used for practical earthquake monitoring.

This study proposes two models for precise time transfer using the BeiDou Navigation Satellite System triple-frequency signals: ionosphere-free (IF) combined precise point positioning (PPP) model with two dual-frequency combinations (IF-PPP1) and ionosphere-free combined PPP model with a single triple-frequency combination (IF-PPP2). A dataset with a short baseline (with a common external time frequency) and a long baseline are used for performance assessments. The results show that IF-PPP1 and IF-PPP2 models can both be used for precise time transfer using BeiDou Navigation Satellite System (BDS) triple-frequency signals, and the accuracy and stability of time transfer is the same in both cases, except for a constant system bias caused by the hardware delay of different frequencies, which can be removed by the parameter estimation and prediction with long time datasets or by a priori calibration.

In this study, a unified model for BeiDou Navigation Satellite System (BDS) wide area and local area augmentation positioning based on raw observations has been proposed. Applying this model, both the Real-Time Kinematic (RTK) and Precise Point Positioning (PPP) service can be realized by performing different corrections at the user end. This algorithm was assessed and validated with the BDS data collected at four regional stations from Day of Year (DOY) 080 to 083 of 2016. When the users are located within the local reference network, the fast and high precision RTK service can be achieved using the regional observation corrections, revealing a convergence time of about several seconds and a precision of about 2–3 cm. For the users out of the regional reference network, the global broadcast State-Space Represented (SSR) corrections can be utilized to realize the global PPP service which shows a convergence time of about 25 min for achieving an accuracy of 10 cm. With this unified model, it can not only integrate the Network RTK (NRTK) and PPP into a seamless positioning service, but also recover the ionosphere Vertical Total Electronic Content (VTEC) and Differential Code Bias (DCB) values that are useful for the ionosphere monitoring and modeling.