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FY-3G precipitation satellite launched in April 2023 is the first dedicated precipitation measurement satellite in China. The dual-frequency precipitation measurement radar (PMR) is the core instrument on the satellite. Because the backscattering performance of the vast ocean area is relatively stable, the calibration accuracy of the on-orbit radar can be tested by studying the backscattering cross-section of the sea surface. FY-3G PMR level 1 data in July 2023 and GPM DPR (global precipitation measurement, dual-frequency precipitation radar) level 2A data are used to analyze the mean value and mean square error of the global sea surface backscattering cross section under no-rain conditions to evaluate the radar performance. At the same time, the theoretical model of ocean surface backscattering is studied to simulate the sea surface backscattering cross-section under the condition of no rain, and the sea surface backscattering cross-section is compared with the actual radar measurement, so as to realize the preliminary evaluation of FY-3G PMR calibration accuracy. Furthermore, the accuracy of FY-3G PMR calibration is evaluated by the ocean calibration test results of GPM DPR data. Test results of ocean calibration accuracy show that when the incidence angle of FY-3G PMR Ku-band is less than 15°, the deviation between the observed value and the model simulation value is small. The deviation of FY-3G PMR ranges from 1.65 to 2.73 dB, while the standard deviation ranges from 0.74 to 1.82 dB. The deviation of FY-3G PMR Ka-band at an 18° incidence is less than 0.27 dB, and the standard deviation of the deviation is 3.49 dB. The calibration deviation of FY-3G PMR and GPM DPR is relatively constant, with the difference is primarily attributed to the backscattering statistical characteristics of the data itself. The stability of the backscattering data of FY-3G PMR Ku- and Ka-band sea surfaces at each incidence angle is comparable to that of GPM DPR. Gas attenuation is not considered at the moment. In the future, the impact of gas attenuation on the Ku- and Ka-band ocean calibration accuracy validation will be further evaluated, and the systematic deviation of FY-3G PMR will be corrected.

Fermented fruit and vegetable products are an important part of traditional fermented food in China. During production, fresh vegetables and fruits are used as raw materials. The fermentation is conducted by the interactions between microorganisms including lactic acid bacteria and fungi which are naturally carried by raw materials. After fermentation, the composition and quantity of microorganisms in fruits and vegetables tend to become out of control, which often leads to post-acidification, softening, spoilage and other problems. Therefore, the development of sterilization technology suitable for fermented fruit and vegetable products has important industrial value. Compared with the destructive effect of traditional heat sterilization, the non-thermal sterilization technology without heating can not only kill the spoilage and pathogenic microorganisms, but also reduce the impact on probiotics, and greatly alleviate the deterioration of fermented fruit and vegetable products. Therefore, non-thermal sterilization technologies have gradually become one of the research hotspots in the field of fermented fruit and vegetable products sterilization. In this paper, the application progress of common non-thermal sterilization technologies in fermented fruit and vegetable products is reviewed. The sterile effect and influencing factors of non-thermal sterilization technologies in fermented fruit and vegetable products are summarized. Its influence on quality and safety attributes of products is discussed. The aim of this study is to provide a theoretical basis for the large-scale application of non-thermal sterilization technologies in the industrial production of fermented fruit and vegetable products.

To enhance the low-carbon construction level of subway stations, this paper, based on life cycle theory and the carbon emission factor method, summarizes the carbon emission calculation methods and relevant standards. Preliminary versions of the ''Carbon Emission Database Software for subway station Civil Engineering'' and ''Carbon Emission Calculation Software for subway station Civil Engineering'' were developed, enabling rapid calculation of carbon emissions for subway stations. From the perspective of low-carbon construction, a subway station in Guangzhou was used as an example to calculate the carbon emissions of three low-carbon construction methods. The results indicate that: (1) The carbon emission intensity of the materialization phase of the case station using the cover excavation reverse method is 3.46 tCO2e/m², demonstrating a lower carbon advantage compared to the other two methods; (2) The carbon emission of the building materials production phase accounts for over 84 % of the total carbon emission during the materialization phase for all three methods, making it the main source of carbon emission in the materialization phase of subway stations; (3) For subway stations of the same cost, the carbon emission of the open cut method is 13.77 % higher than that of the cover-excavation method and 10.18 % higher than that of the cover excavation reverse method.

Abstract Background The department of anesthesiology is the main battlefield for the treatment of acute and critical patients, with high work risk and high work pressure. Due to the particularity of the working environment and nature of work, medical staff have become a group with a high incidence of occupational exhaustion and presenteeism. Objective To investigate the current status of presenteeism among anesthesiology nurses in China and to analyze the related influencing factors. Methods Three hundred twelve anesthesiology nurses in Sichuan Province were surveyed by means of general data questionnaire, presenteeism scale, work-family conflict scale, perceived social support scale, occupational commitment scale and stress resistance scale from September to November 2023 by convenience sampling method. Results The total score of presenteeism was (14.67 ± 3.92), the score of work-family conflict was (45.44 ± 15.90), the score of professional commitment was (87.28 ± 14.30), and the score of perceived social support was (66.04 ± 12.78). The evaluation score of stress resistance was (73.35 ± 11.54). The results of multivariate analysis showed that age, education, mode of employment, position, overtime hours per week, work-family conflict, perceived social support and stress resistance were the factors that affected the presenteeism of anesthesiology nurses, which could explain 44.1% of the total variation. The position ( β = 0.296, P

Summary: Reactive changes of glial cells during neuroinflammation impact brain disorders and disease progression. Elucidating the mechanisms that control reactive gliosis may help us to understand brain pathophysiology and improve outcomes. Here, we report that adult ablation of autism spectrum disorder (ASD)-associated CHD8 in astrocytes attenuates reactive gliosis via remodeling chromatin accessibility, changing gene expression. Conditional Chd8 deletion in astrocytes, but not microglia, suppresses reactive gliosis by impeding astrocyte proliferation and morphological elaboration. Astrocyte Chd8 ablation alleviates lipopolysaccharide-induced neuroinflammation and septic-associated hypothermia in mice. Astrocytic CHD8 plays an important role in neuroinflammation by altering the chromatin landscape, regulating metabolic and lipid-associated pathways, and astrocyte-microglia crosstalk. Moreover, we show that reactive gliosis can be directly mitigated in vivo using an adeno-associated virus (AAV)-mediated Chd8 gene editing strategy. These findings uncover a role of ASD-associated CHD8 in the adult brain, which may warrant future exploration of targeting chromatin remodelers in reactive gliosis and neuroinflammation in injury and neurological diseases.

Objectives: This study was designed to analyze entrepreneurial competency and enhance college students' abilities in innovation and entrepreneurship. Methods: Ten relevant factors were summarized based on the interview records. Relevant data were collected through questionnaires and tested for reliability and validity. The effectiveness of the ten factors on entrepreneurial competency was tested using the regression analysis method. Then, an analytic hierarchy process model of entrepreneurial competency was established to calculate the relevant weights. Findings: The data collected from the survey questionnaire had sufficient reliability and validity. The ten relevant factors were effective in developing entrepreneurial competence. The weight distribution in the analytic hierarchy model indicated that entrepreneurial knowledge was most important, followed by entrepreneurial ability, and intrinsic potential was least significant. Novelty:The novelty of this article lies in not only verifying the effectiveness of relevant factors through regression analysis but also further analyzing the weight of these factors through an analytic hierarchy process. Doi: 10.28991/HIJ-2023-04-04-011 Full Text: PDF

This study presents a novel risk-assessment methodology for deep foundation pit projects in karst regions, aimed at enhancing project safety and decision-making processes. This approach amalgamates fuzzy dynamic Bayesian networks with a refined Dempster–Shafer (DS) evidence theory to tackle the intricate uncertainties present in such contexts. A comprehensive risk index system, derived from historical accident cases, relevant standards, and the literature, encompasses environmental, design, construction, and management factors. Initial probabilities for each risk factor are determined through the integration of expert knowledge and fuzzy theory. The enhanced Dempster–Shafer theory is utilized to fuse diverse information sources, culminating in a robust and dynamic risk evaluation model. This model leverages real-time monitoring data to dynamically assess and adjust risk levels throughout the construction process. The validation of the proposed method is demonstrated through a detailed case study of the Guangzhou Tangxi Section 1 deep foundation pit project, which effectively identified critical risk factors and facilitated proactive construction strategy adjustments. To further evaluate the reliability of the methodology, comparisons were made with three alternative methods, and applications were conducted on three additional deep foundation pit projects. These comparative analyses confirm the superior reliability and applicability of the proposed methodology across varied scenarios.

The stability of underground diaphragm walls is crucial for ensuring the safety and integrity of trench excavations in geotechnical engineering. This study addresses this critical issue by proposing a novel destabilization mechanism based on a sliding body model specifically designed for diaphragm wall trenching operations. The research employs an analytical framework rooted in soil mechanics and plasticity theory, utilizing limit equilibrium analysis to develop a method for calculating the minimum required slurry density and corresponding safety factor for trench stability. The study compares two distinct approaches to slurry density computation, analyzing their sensitivity to various influencing factors. Theoretical findings are validated through multiple real-world engineering case studies. Comparative analysis demonstrates the superiority of the proposed method, particularly in assessing trench stability within clay layers. Key variables influencing the safety factor are identified, including trench length, slurry density, soil friction angle, and the relative height difference between slurry and groundwater levels. Results indicate that actual slurry densities observed in practice consistently fall within the bounds predicted by the theoretical calculations. This research contributes a valuable theoretical framework to the field of diaphragm wall construction, offering improved accuracy in stability assessments and potentially enhancing safety in geotechnical engineering projects.

In the simulation of foundation pit excavation, the traditional element birth–death method commonly used tends to encounter issues such as uncoordinated deformation and changes in the constitutive model, affecting the accuracy of the prediction results. To address these issues, this study proposes the use of element tracking. By duplicating elements for temporary supports or structures requiring changes in material properties and appropriately activating or deactivating them at the right moments, the simulation of the foundation pit excavation process can be achieved more precisely. Using the construction process of the Tangxi Passenger Transport Station’s comprehensive transportation hub foundation pit as an example, this study applied the proposed simulation method and compared the results with actual measurements, demonstrating its effectiveness. This research offers a more accurate approach for simulating foundation pit excavation and provides a reference for similar numerical simulation problems.

The present study aimed to determine the capsular serotype distribution and antimicrobial drug resistance patterns of Haemophilus influenzae from children in the Kunming region of China. This information could guide policymakers in clinical treatment. In the present study, H. influenzae isolates were tested for their serotypes, antimicrobial susceptibility pattern, and presence of β-lactamases. One-hundred forty-eight H. influenzae strains isolated from children 0–2 years old were investigated for capsular types by glass slide agglutination and molecular methods, and biotyped by the biochemical reactions. The drug resistance-encoding genes TEM-1, ROB-1, and the ftsI gene mutations PBP3-3, and PBP3-BLN were detected with real-time quantitative polymerase chain reaction (qPCR). The prevalence of β-lactamase-producing strains (60.3%) was significantly higher (p < 0.05) than non-enzyme-producing strains. β-Lactamase-producing strains were multidrug resistant to various antibiotics such as ampicillin, tetracycline, sulfamethoxazole/trimethoprim, chloramphenicol, cefuroxime, and cefaclor. Among β-lactamase-producing strains, the detection rates of the TEM-1, PBP3-BLN, PBP3-s, and ROB-1 were 54.1%, 18.9%, 11.8%, and 6.9%, respectively. The biotyping results show that most H. influenzae strains were of type II and III. Non-typeable H. influenzae (NTHi) accounted for 89.3% of the strains. NTHi strains were the most prevalent in this region; most belonged to biological types II and III. β-Lactamase-positive ampi-cillin-resistant (BLPAR) strains were prevalent among H. influenzae isolates in this region.

Hotpot provides a multilevel unique flavor experience and is preferred by consumers who value various taste preferences. In the present study, results showed that alcohols, phenols, hydrocarbons, and others were the commonly predominant volatiles in all butter hotpot samples (74.43%∼92.92%). However, there were merely 25 codetected compounds determined among a total of 318 aroma compounds because of the discrepant ingredients and processing technique of hotpot samples, which were sampled from several representative manufacturers. Therefore, for the first time, multiple GC-Q-TOF/MS and GC-Orbitrap-MS methods were performed to explore the more 44 potential aroma compounds of butter hotpot, in which alpha-terpinyl, acetate, nonanal, piperitone, and (E)-lignstilde could further cause the differences in flavor intensity of spices aroma, smell of grease, and roasted, charred, and nutty (p

In recent years, sexual assault cases have been on the rise, seriously infringing the legitimate rights and interests of women and children, causing widespread concern in society. DNA evidence has become the key evidence to prove the facts in sexual assault cases, but lack of DNA evidence or only DNA evidence in some sexual assault cases leads to unclear facts and insufficient evidence. With the emergence of high-throughput sequencing technology and the development of bioinformatics and artificial intelligence, new progress has been made in the study of human microbiome. Researchers have begun to use human microbiome for difficult sexual assault cases indentification. This paper reviews the characteristics of human microbiome, and its application value in the inferences of the body fluid stain origin, the sexual assault method, the crime time, etc. In addition, the challenges faced by the application of the human microbiome in practical case handling, the solutions and future development potential are analyzed and prospected.

Abstract In the development of anti-breast cancer drugs, the quantitative structure-activity relationship model of compounds is usually used to select potential active compounds. However, the existing methods often have problems such as low model prediction performance, lack of overall consideration of the biological activity and related properties of compounds, and difficulty in directly selection candidate drugs. Therefore, this paper constructs a complete set of compound selection framework from three aspects: feature selection, relationship mapping and multi-objective optimization problem solving. In feature selection part, a feature selection method based on unsupervised spectral clustering is proposed. The selected features have more comprehensive information expression ability. In the relationship mapping part, a variety of machine learning algorithms are used for comparative experiments. Finally, the CatBoost algorithm is selected to perform the relationship mapping between each other, and better prediction performance is achieved. In the multi-objective optimization part, based on the analysis of the conflict relationship between the objectives, the AGE-MOEA algorithm is improved and used to solve this problem. Compared with various algorithms, the improved algorithm has better search performance.

The optimal proportion of alkali-activated steel slag–slag cementitious materials is investigated by considering the combined effects of steel slag content, alkali content, water glass modulus, and water–binder ratio using the Box–Behnken design in response surface methodology. Qualitative and semi-quantitative analyses of X-ray diffraction (XRD) patterns and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) images are conducted. The microstructural mechanism is elucidated based on the chemical composition, surface morphology, and microscale pore (crack) structures of the samples. A microreaction model for the alkali-activated steel slag and slag is proposed. The optimal composition for alkali-activated steel slag–slag cementitious materials is as follows: steel slag content, 38.60%; alkali content, 6.35%; water glass modulus, 1.23; and water–binder ratio, 0.48. The strength values predicted by the response surface model are p1d = 32.66 MPa, p7d = 50.46 MPa, and p28d = 56.87 MPa. XRD analysis confirms that the compressive strength of the sample is not only influenced by the amount of gel formed, but also, to a certain extent, by the CaCO3 crystals present in the steel slag, which act as nucleation sites. The SEM-EDS results confirm that the gel phase within the system comprises a hydrated calcium silicate gel formed through the reaction of volcanic ash and geopolymer gel formed through geo-polymerization. Analysis of the pore (crack) structure reveals that the compressive strength of the specimens is primarily influenced by porosity, with a secondary influence of the pore fractal dimension.

In order to meet the development requirements of the data age, clustering, co-occurrence and emergence analysis was performed for the relevant literatures concerning pipeline integrity management at home and abroad in 2000–2020, and the knowledge graph of pipeline integrity management was constructed. Then, on the basis, the characteristics of research on pipeline integrity management were summarized with the research direction in this field predicted. The results show that the research scope of pipeline integrity management in China is gradually expanded and the research level is gradually deepened, which is internationally advanced. Generally, the keyword cluster is formed at the time close to that at abroad, but the research topics are quite different. The emerging words in recent years show that the research trend of pipeline integrity management in China will focus on the risk assessment, safety and high consequence areas, while the international pipeline integrity management in the next few years will be mainly developed in the direction of simulation, mechanics and failure possibility. Thus, the research results will provide some guidance to the research and development direction of pipeline integrity management in the future.(6 Figures, 5 Tables, 30 References)

The early cracking of mass concrete in low temperature environment has always been a hot issue in the industry. The exploration of the development law of temperature and strain of mass concrete in low temperature environment is conducive to prevent its early cracking. Strain gauges are embedded in the upper, middle, and lower layers of the four measuring points of mass concrete on site to obtain the development data of early temperature and strain. Then analyze these data and reveal their internal laws. The following conclusions are drawn: (1) During the 0–30 h of concrete curing monitoring, the temperature in the middle layer of concrete is the highest, followed by the temperature in the upper layer, while in the subsequent monitoring period, a cooling gradient is formed from the lower layer to the upper layer. (2) The maximum compressive strain of concrete mainly occurs in the middle layer, and the maximum temperature and maximum compressive strain of concrete are positively correlated with its thickness. The ratio value of temperature difference between inside and outside of concrete and its thickness is the key factor affecting its external tensile strain. The strain of concrete decreases with the decrease of temperature and the development of strength, and finally tends to be stable. (3) The thickness of concrete has a significant effect on the complexity of the early strain development curve, but it does not affect the time when the strain development tends to be stable. (4) The decisive factor affecting the spatial correlation of concrete strain development is not its thickness and temperature, but the specific factors need to be further discussed.

In order to realize rapid and accurate warning of tunneling faces gas outburst risk, based on the relationship between the characteristics of gas emission in working face and the “three elements” of outburst, a real-time early warning index system including in-situ stress coefficient, gas concentration and gas emission coefficient was established. We combine the SVM and PSO algorithms to build the PSO-SVM outburst warning model, defines the classification principles of outburst warning labels. On this basis,?an outburst warning system of heading face is developed by integrating Spark big data platform. The system includes 8 modules, such as model management, risk identification and Spark configuration. Taking the monitoring and control system of heading face in a mine in Guizhou as the data source, 1059 groups of early-warning indicators and corresponding early-warning grade labels were selected and imported into the data mining model for intelligent learning and training, and the system was applied to the outburst risk early-warning of the heading face. The operation results show that the prediction accuracy of the outburst warning model test set is 92%, and the system can accurately predict the outburst dynamic phenomenon 22 min before the occurrence of the working face.

The stability of geogrid-reinforced soil structure is closely related to the interface characteristics between geogrid and soil. However, the creep behavior of the soil–geogrid interface is still unrevealed. In this study, using a modified stress-controlled pullout device, influence of the normal pressure, dry density, and water content on creep behavior of interface of compacted loess and high-density polyethylene (HDPE) geogrid is investigated. A three-parameter empirical model and a Merchant element model were established through fitting analysis. Analysis results show that the normal pressure, dry density, and water content have significant effects on the creep shear displacement of the reinforced soil interface. Under the same pullout level, creep displacement of the interface increases with the increase of water content and decreases with the increase of dry density and normal pressure. Both the three-parameter empirical model and Merchant element model can describe the creep characteristics of the reinforced soil interface. The Merchant model is more accurate in the early stage, while the three-parameter empirical model is more suitable for predicting the long-term creep deformation of the interface of compacted loess and geogrid.

In view of problems of complicated calculation process, strong subjectivity and low accuracy in existing prediction methods of coal and gas outburst, a principal component-Fisher discriminant model was constructed and applied to the prediction of coal and gas outburst grade in a coal mine. Based on analysis of gas factors, coal structure and geological structure, the factors that affect coal and gas outburst of the coal mine included gas pressure, gas content and initial velocity of gas release and so on were obtained. On the basis of 23 groups measured data of coal and gas outburst of the coal mine, firstly, the principal component analysis model was used to do dimension reduction of influencing factors of the mine coal and gas outburst, 5 principal components with high index correlation were extracted. Then the 5 principal components were input into Fisher discriminant model, and the grade of coal and gas outburst of samples was predicted according to discriminant function. The application results show that the principal component-Fisher discriminant model has high credibility, and can accurately predict coal and gas outburst grade, the training sample accuracy is 100%, the predicted results of the tested sample are also consistent with the actual situation of coal and gas outburst of the coal mine, misjudgment rate of 0, which provides a new method of accurate prediction of coal and gas outburst.

Taking the loess high-fill project of Lv Liang airport in China as the research object, large-scale centrifugal tests were carried out to investigate the deformation characteristics of the collapsible loess ultrahigh-fill slope under natural moisture content and saturated state by using a joint model of undisturbed loess and remolded loess. The results show that the consolidation deformation of the collapsible loess ultrahigh-fill slope is the main factor causing its deformation. The post-construction deformation amount and deformation rate are large in the early stage, and the relationship between the post-construction deformation and thickness of filling body is linear. When the water content of soil increases due to infiltration, the consolidation of the filling body and the collapse of the undisturbed foundation loess will cause settlement and deformation of the slope. The slope may crack along the soft zone formed when the water infiltrates. When failure occurs, the sliding surface will pass through the collapsible soil layer. The contact surface between the collapsible loess layer and the adjacent soil layer is part of the sliding surface, and the contact surface with a relatively low strength will be damaged first. When the strength difference between adjacent soil layers is large, the upper soil layer on the slip surface shows a typical translational sliding mode. The slip surface is approximately arc-shaped, and there is a transition layer with a specific thickness between the slip surface and contact surface. The water content of the high-fill slope has a great influence on the post-construction settlement of the slope crest and slope stability. The post-construction settlement of the slope crest increases with the increase in the water content of the filling body, and the stability coefficient of the slope decreases with the increase in the water content of the filling body. In the saturated state, the sliding force of soil increases, the shear strength decreases, and the stability of high fill slope decreases. Therefore, it is necessary to strengthen the inspection of the rationality of drainage system design in slope construction to ensure slope safety.

Property of geotechnical materials has inherent uncertainty due to the complex formation process and inevitable test error. However, existing long-term deformation prediction methods for geotechnical structure such as a filling embankment are deterministic, which ignores the uncertainty of soil property. In this study, the uncertainty of creep behavior of compacted loess was investigated through repetitive creep tests and statistical analysis. Five different loading levels and two loading modes were considered in the tests. The creep test was repeated 45 times for each condition. Through a statistical analysis for the test results, a modified Merchant creep model was established to improve the accuracy of long-term deformation prediction. An empirical transformation equation between staged loading and separated loading mode of the creep test results was also introduced to improve applicability of the method. On this basis, a non-deterministic predication method for post-construction settlement of loess fill embankment was proposed. Furthermore, the proposed method was applied to the prediction of the post-construction of a 61.5 m loess filling embankment. The measured on-site post-construction settlement value falls within the 95% confidence interval of the predicted range which proves the efficiency and practicability of the proposed non-deterministic predication method. Compared to deterministic methods, the proposed method can describe the predicted deformation in a probabilistic way in the form of contour plot. The proposed method provides a basic approach for the probabilistic design and reliability assessment of filling engineering.

This study aimed to reveal the impact of the severe drying-wetting process on the safety and stability of high-altitude dumps. Numerical calculations were conducted for the open mining dump of limestone mines for cement in high-altitude mining areas. The distribution law equation of the matric suction and the shear strength equation were imported for unsaturated soil based on the unsaturated-saturated seepage theory. Therefore, the evolution characteristics of the unsaturated-saturated seepage field and the stability of the dump were studied under severe drying-wetting. The results indicated the following rules: As the intensity of the wetting-drying alternation increased, the surface soil on the dump changed from an unsaturated to a saturated state, the matric suction continued to decrease until it reached zero, the shear strength decreased, and the unsaturated area shrank. The dump slipped under the influence of the drying-wetting alternation, the sliding area was the dump itself, and developed to the deep layer as the intensity of the drying-wetting alternation strengthened. The cumulative settlement value of the dump increased with time and eventually stabilized, and the maximum accumulative settlement value calculated by simulation was in good agreement with the actual monitoring value. The safety factor decreased as the intensity of the drying-wetting alternation increased.

Excavations in a soft soil area are usually associated with substantial difficulties. Taking a special-shaped deep foundation pit in Hangzhou soft clay as the research object, the excavation performances, including groundwater level height, axial force, lateral wall, and soil deflection, and ground surface settlement were monitored and summarized based on the data published in the literature on similar excavations in Hangzhou, P. R. China. The following conclusions are drawn: (1) The axial forces of the struts dynamically change during the excavation and construction or removal of adjacent braces. (2) The ratio between the measured maximum wall deflection and excavation depth δh−max/He is 0.14–0.17%, larger than those in Shanghai. (3) The surface settlement behind the wall has an obvious primary influence zone and secondary influence zone, characterized by a “groove shape” and “triangle shape,” respectively. The maximum ground surface settlement δv−max ranges from 0.29% to 0.5% of the excavation depth. (4) The distribution of the ground settlement was analyzed. The relationship between the maximum settlements δv−max is between 1.28 δh−max and 3.72 δh−max. Moreover, ABAQUS software with Mohr–Coulomb soil models was used for model analysis of the construction process. The research results have important significance for the effective prevention of foundation pit accidents and the optimal design of deep foundation pit projects.

Taking China’s first application of domestic shield tunneling in a water-rich sand layer for crossing a high-speed railway as research background, the influence of changes in the shield tunneling parameters on ground settlement is analyzed based on field tests, and a construction control method suitable for shield tunneling under a risk source in a water-rich sand layer is proposed. The test results show that the use of 10% sodium bentonite as the soil modifier for soil pressure balance shield tunneling into the water-rich sand layer has advantages, while adding 50% loess into the bentonite slurry in the gravel sand layer can greatly improve the impermeability of the soil; the settlement of soil can be effectively reduced by using the special segment with grouting holes for deep grouting and applying the adaptive transformation of the shield cutter. Based on the statistical analysis results, a reasonable range for the cutter head torque, cutter head speed, chamber pressure, bentonite injection volume, and advanced speed in the water-rich sand layer can provide a construction control basis for similar projects and provide data support for the compilation of relevant specifications.

Small-diameter jacked piles are widely used in civil engineering. The formation and development of the soil-plugging effect and surface frictional behavior of jacked piles have a high impact on the construction process and pile quality. Clarifying the developmental pattern of the soil-plugging effect and the change law of frictional force forms the premise of scientific construction and construction quality. Firstly, we carried out two groups of in situ tests on the small-diameter jacked piles, recording the relationship between penetration depth and resistance force. Then, the discrete element method (DEM) was used to analyze the mechanical behavior of the small-diameter jacked piles during the construction process. The particle flow code (PFC) 2D was used to carry out the DEM simulation. The research results show that pile resistance exhibited an irregular development trend as the construction process proceeded. There is a sudden change in pile resistance when the pile tip reaches the interface of certain soil layers. Both tests revealed the same phenomenon, yet both occurred at different depths. The DEM analysis showed that plug sliding was the main reason for the above phenomenon. The difference in strength and stiffness of adjacent soil layers causes the soil plug to slide, leading to a sudden change in pile resistance. When the upper layer is soft and the layer below is hard, this phenomenon is especially obvious. This also leads to a difference in the location of the sudden change in pile resistance between the two groups of tests. The research results of this paper can be helpful for revealing the relationship between the soil-plugging effect of small-diameter jacked piles and the development of pile resistance and also provides a reference for relevant engineering construction and design.

In view of problems of low prediction accuracy, poor stability and slow training of current coal and gas outburst intensity prediction, a prediction method of coal and gas outburst intensity based on LLE-FOA-BP model was proposed. Essential characteristics of raw data of coal and gas outburst influencing factors are extracted taking use of the advantage of nonlinear data feature extraction of LLE algorithm, effective reconstruction factors are formed, and redundant information and noise between data are reduced. The weight and threshold of BP neural network are optimized by using FOA algorithm's strong global optimization ability to avoid falling into local minima and improve parameter optimization efficiency. Effective reconstruction factors are input into the optimized BP neural network for training, so as to realize quick and accurate prediction of coal and gas outburst intensity.The test results show that the average relative error of LLE-FOA-BP model is 8.06%, variance of relative error is 3.69, and training accuracy of 10-8 is achieved after 24 iterations, which verifies the model can improve robustness and learning efficiency while ensuring prediction accuracy.

The role of fungi in the biogeochemical cycling of gold remains unclear. Here the authors show that fungi can initiate gold oxidation under supergene conditions, thereby impacting gold mobilisation and secondary deposit formation in terrestrial environments.

Due to the large cross-section design of large-diameter shield tunnels, most of the rocks and soils it crosses are composite strata with upper soft and lower hard. In order to reduce the construction cost of shield working shafts, large-diameter shield launching is usually buried at a shallow depth. Based on the typical large-diameter slurry shield tunnel, the following research results were obtained according to field monitoring and PLAXIS 3D finite element simulation. (1) The electronic level is used to monitor the surface settlement, and the field monitoring data were obtained; the surface settlement duration curve at the axis of the shield tunnel during the construction period can be divided into four stages: pre-deformation, shield passing, shield tail exit and shield moving away, of which the surface settlement accounts for the largest proportion during the shield passing. (2) In order to ensure the accuracy of the numerical simulation results, the linear shrinkage of the shield needs to be considered in the modeling. (3) The maximum surface settlement value at the center of the tunnel increases with the increase of the support pressure; when the support pressure exceeds 300 kPa, the surface uplift and the settlement caused by the formation loss will offset, and the surface settlement will decrease instead. The maximum surface settlement value is inversely proportional to the grouting pressure, but with the increase of the grouting pressure, the maximum uplift of the surface continues to increase. (4) With the numerical simulation of excavation step construction, the surface uplift increases with the increase of grouting pressure and shield radius, and decreases with the increase of shield buried depth.

When large-diameter slurry shields are tunneling in a composite stratum with a high clay content, the cutter head may form a mud cake. After the mud cake is formed, it will cover the cutter and reduce the opening rate of the cutter head, thus reducing the penetration of the cutter and the driving speed. Based on a road upgrading project, this paper studies the prevention and treatment of a mud cake and forms a set of comprehensive treatment methods. For a large mud cake, through theoretical analysis, two calculation methods of the cutter head sealing coefficient are obtained, and the cutter head sealing coefficient relationship model is established. Comparing the calculated cutter head’s actual opening coefficient with the required cutter head opening coefficient can provide a judgment basis for the time of manual warehousing. For medium and small mud cakes, the numerical simulation is carried out based on the cutter head and the scouring system, the distribution characteristics of the flow field near the cutter head are analyzed, and the angle of the central scouring hole is optimized. For a small mud cake, hydrogen peroxide is selected as an additive through microscopic mechanism analysis. The effect of the hydrogen peroxide solution concentration on dissolving a mud cake is obtained through laboratory tests, and its effectiveness is verified through field tests. The research results can provide a reference for the mud cake prevention of slurry shields in similar strata.

Geological materials have randomness in nature. Statistical analysis can help revealing the variation pattern of the material parameters and the reliability of the slope. In this paper, the probability distribution and variability of shear strength parameters of typical Q2 and Q3 loess in Northwest China were statistically analysed using the collected geological survey data in Yan`an, Shaanxi Province. Resulting probability properties were applied to the reliability analysis for the natural and fill slope in loess area using the Monte Carlo Method. Finally, an optimization analysis was carried out for the fill slope in the background engineering project. Research results show that normal distribution and lognormal distribution can be used to describe the statistical properties of c and φ of Q2 and Q3 loess. Variance of c is large while the variability of φ is relatively small. The influence of the variability of φ on the reliability index of loess natural slope is generally larger than that of c. On the contrary, influence of the variability of c on the reliability index of the fill slope is generally greater than that of φ, which is related to the structural and uniformity of the soil. Finally, relation between slope height and minimum gradient coefficient is linear when the failure probability of fill slope is less than 10%. Results in this study can be used as a reference for the slope design and construction for the cut and fill engineering in loess area.

So far, there have been a large number of diaphragm walls in the Yangtze River Delta as engineering examples of deep foundation pit maintenance structures in subway stations, but there is a lack of systematic research and summary on the deformation characteristics of ground connecting walls. This study aimed to clarify the deformation law of the diaphragm wall during the excavation of a deep foundation pit in a soft soil region. Based on the monitoring data of the diaphragm wall of the deep foundation pit of the Hangzhou metro station, the monitoring data of the deep foundation pits of 15 subway stations in Shanghai and Ningbo cities around Hangzhou were considered. Grouping and classification methods were used to analyze the similarities and differences in the deformation characteristics of the diaphragm wall in the three regions. The results indicate the following: the maximum lateral deformation of the diaphragm wall in Hangzhou increases linearly with the relative depth of the maximum lateral deformation. The maximum lateral deformation of the foundation pit in Hangzhou is 0.072% H∼0.459% H, with a mean of 0.173% H. The wall deformation in Hangzhou varies significantly with the depth of the foundation pit, but the influence of the depth of the foundation pit on the wall deformation is considerably less than that in Shanghai and Ningbo. The corresponding position of the maximum lateral deformation in the excavation depth increases linearly with the excavation depth of the foundation pit, and the corresponding position of the lateral deformation of the diaphragm wall in Shanghai is more affected by the excavation depth of the foundation pit. The lateral deformation of the diaphragm wall increases rapidly in the range of 0 H–0.5 H, and the maximum lateral deformation occurs at 0.5 H–1.1 H.

Geostatic stress field procedure is the first and the most important step for the numerical simulation of geotechnical engineering, which greatly influences the simulation results. Traditional methods often fail when the model is complex. In this paper, based on finite element method (FEM) software ABAQUS, failure reasons of four commonly used methods for the geostatic stress field are studied. According to the analysis results, a new set of methods, which can provide reasonable displacement and stress field results under complex conditions, is proposed. The proposed methods follow the principle that the stress of different materials should be obtained separately to avoid stress distortion. Then, the accuracy and applicability of the proposed method are verified through a comparison study and a specific application. This study provides a theoretical basis for the method of geostatic stress field procedure under complex condition and can serve as a reference for relevant studies.

Coal samples of six outburst coal seams in coal-rich areas in Guizhou province were taken as research objects to analyze size grade of pore, fractal dimension, fractal characteristics and relationship between the fractal characteristics and gas adsorption or coal permeability by use of liquid nitrogen adsorption experiment and mercury intrusion experiment. The experimental results show that pores of the coal samples with different grades have good fractal characteristics, which can show porosity and pore distribution characteristics. The fractal dimension can be used to quantitatively analyze pore characteristics of coal samples. There is a positive correlation between the fractal dimension of micro pore of the coal samples and gas adsorption value. Gas adsorption capacity of coal samples in different coals is quite different. The fractal dimension of small pore reflects simple pore structures of coal samples and pore similarity among coal samples. The fractal dimensions of medium pore, large pore, pore fracture and micro fracture show that pore distribution trend of each coal sample is similar. Pores with some size grades develop badly, so measure for increasing the permeability of coal seam are needed to improve gas drainage effect.

Saturated sandy stratum often makes tunnel excavation exceedingly difficult owing to its high water content. The artificial ground-freezing (AGF) method is an effective way to reduce the construction risks in such stratum; however, the AGF mechanism in the saturated sandy stratum of a collapsible loess area still lacks sufficient research. Based on field tests and numerical simulations, this study investigates the regularity of the temperature development, frost heave, and thaw subsidence distribution during the cross passage construction of a saturated sandy stratum in a collapsible loess area, using the AGF method. The results showed that the inward development rate of the frozen soil wall in the saturated sandy stratum was faster than its outward development rate. The gradient of the soil cooling curve was positively related to the longitudinal depth of the cross passage. The thickness of the frozen soil wall calculated by the slowest development rate of the frozen soil was conservative. The application of the pressure relief hole was beneficial to the release of the frost-heaving force and the control of the frost-heaving displacement. The pressure gauge pressure increase could be used as an identifier for the closure of a frozen soil wall. After excavation, the inner wall of the cross passage moved toward the inner space of the passage.

In practice, when the training set and testing set are mismatched, performance of steganalysis can not be guaranteed. The transfer learning aims at using the knowledge learned from one domain to help complete the learn-ing task in the new domain, and does not require the same distribution assumption. A more comprehensive review of mismatched steganography research status was made and the mismatch factors were analyzed. Methods on in-stance-based transfer learning were presented to solve the test mismatch problem during the steganography detections.

In order to analyze influence of coal particle size on initial speed of methane diffusion, the relationship of particle size and initial speed of methane diffusion of coal samples with different moisture content was tested by use of WT-1 type initial speed of methane diffusion tester. The coal samples were collected in No.4 coal seam in a coal mine with different particle sizes of less than 7 mesh, 7-10 mesh, 10-18 mesh, 18-35 mesh and different moisture content of natural drying, drying, 3%, 5% and 7%. And the initial speed of methane diffusion of coal samples of natural drying and drying for 5 h were tested, which were with different particle sizes of less than 7 mesh & 35-60 mesh,7-10 mesh & 35~60 mesh, and 10-18 mesh & 35-60 mesh under different proportion of 6∶1,5∶2,4∶3,3∶4,2∶5 and 1∶6. The experimental results show that initial speed of methane diffusion of coal samples with different moisture content increases as the particle size decreases, and the particle size smaller, the increasing trend is more obvious; the proportion of coal particles with small particle size in coal seam larger, the initial speed of methane diffusion of coal samples is larger.

Using image processing and recognition, a microstructure-based finite element model (FEM) was established to predict the dynamic properties of SiCp/Al composites at different strain rates ranging from 200 to 14,000 s-1. In the microstructure-based FEM, the irregular SiC particles were randomly distributed in the matrix, and its configurations did not change. The results showed that the flow stress of SiCp/Al composites with low particle volume fraction first increases and then decreases with the increasing of strain rate during the adiabatic compression. The reducing flow stress of SiCp/Al composites is caused by the inner damage and the heat softening of composites. The angular particles in SiCp/Al composites provide more strengthening effect than the circle particles when the strain is 0.62.