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Ephemeral gullies are widely distributed in the hilly and gully region of the Loess Plateau and play a unique role in the slope gully erosion system. Rapid and accurate identification of ephemeral gullies impacts the distribution law and development trend of soil erosion on the Loess Plateau. Deep learning algorithms can quickly and accurately process large data samples that recognize ephemeral gullies from remote sensing images. Here, we investigated ephemeral gullies in the Zhoutungou watershed in the hilly and gully region of the Loess Plateau in China using satellite and unmanned aerial vehicle images and combined a deep learning image semantic segmentation model to realize automatic recognition and feature extraction. Using Accuracy, Precision, Recall, F1value, and AUC, we compared the ephemeral gully recognition results and accuracy evaluation of U-Net, R2U-Net, and SegNet image semantic segmentation models. The SegNet model was ranked first, followed by the R2U-Net and U-Net models, for ephemeral gully recognition in the hilly and gully region of the Loess Plateau. The ephemeral gully length and width between predicted and measured values had RMSE values of 6.78 m and 0.50 m, respectively, indicating that the model has an excellent recognition effect. This study identified a fast and accurate method for ephemeral gully recognition in the hilly and gully region of the Loess Plateau based on remote sensing images to provide an academic reference and practical guidance for soil erosion monitoring and slope and gully management in the Loess Plateau region.

Due to the influence of the monsoon, river runoff in most of China’s river basins is mainly concentrated in the flood season. The distribution is extremely uneven during the year and between the year. It needs to be fully utilized by the reservoir to bring serious challenges to the daily management. Therefore, analyzing the seasonal variation of storm floods, scientifically and rationally staging the flood season can not only give full play to the comprehensive benefits of the reservoir, but also be an inevitable requirement for coordinating reservoir flood control and power generation. Aiming at the several commonly used methods of flood season staging, the case study is carried out, and the applicable conditions are analyzed. Based on these, three new staging methods are proposed. Among them, the improved change point analysis method adopts the linear and nonlinear joint fitting, which improves the commonly used mean value calculation method. In theory, the non-uniformity and seasonality of the reservoir water are more carefully considered, and the flood season is considered to some extent. The distribution law and continuity of floods along the time course; the projection method has a similar theoretical system with the vector statistical method based on the annual maximum sampling method, both of which are based on the intensity of the points, the difference is the point of the latter is projected on the circumference, the partitioning result is selected by manual experience, and the human influence factor is large. The new method is to project the point on the straight line, and quantitatively gives the partitioning method, and is also applicable to the maximum flow of different sequences. The case of the same time, the dynamic clustering method divides the sample set into several subsets according to the similarity between samples, and has the advantage that the calculation amount is small and the genus of the sample can be changed compared with the system clustering method. The research results can provide reference for the reasonable adjustment of the reservoir flood season.

The cellular-counterfort retaining structure, which combines cellular retaining wall with counterfort retaining wall, can effectively increase the height of backfilled retaining walls, and boast a broad prospect in earthwork projects. In the presence of the rib plates of counterfort retaining wall, the soil pressure on the vertical plate of the cellular-counterfort retaining structure is not uniformly distributed in the horizontal direction. The distribution model and size of the pressure directly affects the structural calculation. Through mathematical analysis, the fill between rib plates was divided into horizontal layers. Considering the friction between the fill counterfort in the counterfort section and the soil stripes, the authors derived the soil pressure formulas on the vertical and bottom plates of the cellular-counterfort retaining structure. Through centrifuge model test, the authors discussed the distribution law of soil pressure on the vertical plate of the cellular-counterfort retaining structure, and the influence of counterfort interval on soil pressure. The results show that: The soil pressure at the midspan of the vertical plate between counterforts increased linearly with the depth, and the soil pressure near the counterforts increased from the top to middle and then gradually decreased from the middle to the bottom of the wall. On the side of vertical plate, the soil pressure obeyed the parabola distribution in the wall length direction, i.e., the pressure was smaller on the two ends than in the middle; the soil pressure on the bottom plate decreased with the distance to the vertical plate. The counterfort had an obvious frictional reduction effect on the soil pressure from the fill to the vertical plate, and the effect became increasingly obvious with the growing depth; the effect was weakened when the counterfort spacing increased. The centrifugal model test verified the reasonability of the proposed formulas for the soil pressures in the cellular-counterfort retaining structure.

Surface morphology of the components is a key factor that influences the quality and performance of precision systems. The influence of different morphologies on the contact performance of mating surfaces may be studied by simulating a real rough surface and calculating the contact performance. First, the micro-geometric characteristics of the surfaces of the machined parts are measured by a 3D surface profilometer (NV5000 5022S), and the distribution law of the surface micro-geometric characteristics is obtained by statistical and characterization methods. Second, the rough surface conforming to this law is simulated by a non-Gaussian mathematical algorithm, and the contact model between the mating parts with micro-geometric characteristics of the simulated surface is reconstructed using reverse engineering. Finally, the mechanical properties of the mating surfaces are obtained using a numerical algorithm based on Yoshimura's integral method and tests. The comparison of mechanical properties obtained from numerical analysis and test shows that the maximum errors in the contact stiffness obtained by the two methods are 9.4% (grinding surface) and 11.5% (milling surface), respectively. Therefore, it is feasible to use a non-Gaussian simulation method and Yoshimura's integral method to realize an effective simulation of the micro-geometric characteristics of the surface and the analysis of the contact performance of the mating surface respectively. The results obtained from this study is thus important as a reference for the analysis of the surface morphology and mechanical properties between the matching parts.

Исследование выполнено в связи с перспективами использования дизельного топлива в качестве абсорбента при улавливании паров бензина, вследствие чего температура вспышки низколетучего нефтепродукта снижается. В статье исследовано изменение запаса качества дизельных топлив по температуре вспышки как статистической величины. На примере ЛУКОЙЛ-Пермьнефтеоргсинтеза, ЛУКОЙЛ-Западная Сибирь и ЛУКОЙЛ-Уралнефтепродукта показано, что зимнее и арктическое дизельные топлива ЕВРО (класс 3), как правило, имеют достаточно высокий запас качества по температуре вспышки. Сопоставлен характер распределения данной случайной величины в весенне-летний период на указанных предприятиях в разные годы. Проверена возможность совместной обработки статистических данных о запасе качества по температуре вспышки для разных предприятий в разное время. Определено соотношение объемов дизельного топлива, используемого в абсорбционных установках рекуперации паров, и принимаемого бензина, при котором качество дизельных топлив не пострадает. Результаты исследований могут быть использованы при планировании применения абсорбционных установок рекуперации паров бензина., The study was carried out in connection with the prospects of using diesel fuel as an absorbent when capturing gasoline vapors, as a result of which the flash point of a low-volatile petroleum product decreases. The article examines the change in the quality reserve of diesel fuels by flash point as a statistical value. Using the example of LUKOIL-Permnefteorgsintez, LUKOIL-Western Siberia Kogalymneftegaz CCI and LUKOIL-Uralnefteprodukt LLC, it is shown that EURO winter and Arctic diesel fuels (Class 3), as a rule, have a fairly high quality margin in terms of flash point. The nature of the distribution of this random variable in the spring-summer period at these enterprises in different years is compared. The possibility of joint processing of statistical data on the quality reserve by flash point for different enterprises, in different time periods, has been tested. The ratio of the volumes of diesel fuel used in vapor recovery absorption plants and the gasoline received, in which the quality of diesel fuel will not suffer, is determined. The results of the research can be used in planning the use of absorption units for the recovery of gasoline vapors.

The spontaneous combustion of residual coal in compound goaf formed by shallow and close coal seam mining is one of the difficulties in mine fire prevention and control. In order to explore the mec...

To investigate the impact of an opening and joints with different inclination angles on the mechanical response behavior, the energy evolution characteristics, and distribution law of granite specimens, uniaxial loading tests were performed on the parallel jointed rock samples with an opening. Results indicated an initial decreasing trend of the strength and deformation parameters, which later increases with increased inclination angle, reaching minimum values when the inclination angle is 45°. Evolution curves of the elastic strain energy and dissipated energy with strain of the samples showed step-like gradual mutation characteristics. The peak total energy, peak elastic strain energy, peak dissipated energy, and total input energy during the failure of the samples showed significant nonlinear characteristics with increasing inclination angle. The opening and joints as well as the change of the inclination angle had significant influences on the proportion of the elastic strain energy of the samples prior to the peak, resulting in the difference of the distribution law of input energy. Moreover, the energy mechanism of the sample failure was discussed. Results showed that the energy release was the internal cause of the sudden destruction of the entire rock mass.

Attic karst cave is one of the most common fractured-vuggy structure in Tahe oilfield. In this study, a typical attic-shaped cave was extracted from the geological section of Tahe Oilfield. Under t...

study area is located at the southwest border of Yunnan Province and the southward extended part of Nushan Mountain, with complex and fragile geo-environmental conditions. Deep geological survey and mathematical analytical investigation on the geohazard distribution and hazard-causing mechanisms in this area were carried out in this study. The results revealed that: (1) The development of geohazards was affected differently by different slope shapes, slope structures and elevations; (2) Most of the geohazards were developed in medium shallow cut ridge-like medium-height mountainous geomorphological region and shallow cut steamed bun-like low and medium-height mountainous geomorphological region, and they were relatively concentrated on tectonic zones like fault zones; (3) The slopes formed by loose earth piling up on the surface of Indo-Chinese magmatic rock and Lancang Group metamorphic rock formations were most prone to slope instability and even landslide. The deep study on the geohazard distribution and hazard-causing mechanisms can provide geoscientific basis and reference for the prevention and mitigation work of geohazards under similar geo-environmental conditions.

Identifying distinct tectonic units is key to understanding the geotectonic framework and distribution law of oil and gas resources. The South China Sea and its adjacent areas have undergone complex tectonic evolution processes, and the division of tectonic units is controversial. Guided by block tectonics theory, this study divide the South China Sea and its adjacent areas into several distinguished tectonic units relying on known boundary markers such as sutures (ophiolite belts), subduction-collision zones, orogenic belts, and deep faults. This work suggests that the study area is occupied by nine stable blocks (West Burma Block, Sibumasu Block, Lanping-Simao Block, Indochina Block, Yangtze Block, Cathaysian Block, Qiongnan Block, Nansha Block, and Northwest Sulu Block), two suture zones (Majiang suture zone and Southeast Yangtze suture zone), two accretionary zones (Sarawak-Sulu accretionary zone and East Sulawesi accretionary zone), one subduction-collision zone (Rakhine-Java-Timor subduction-collision zone), one ramp zone (Philippine islands ramp zone), and six small oceanic marginal sea basins (South China Sea Basin, Sulu Sea Basin, Sulawesi Sea Basin, Banda Sea Basin, Makassar Basin, and Andaman Sea Basin). This division reflects the tectonic activities, crustal structural properties, and evolutionary records of each evaluated tectonic unit. It is of great theoretical and practical importance to understand the tectonic framework to support the exploration of oil and gas resources in the South China Sea and its adjacent areas.

Aiming at the problem that it is difficult to control high dust hazard in fully mechanized mining face with large mining height, an airflow-droplet coupled model was established based on the Euler-Lagrange method. Through a custom-developed nozzles atomization experimental system, main parameters were measured, and the built-in butterfly division core nozzle with an aperture of 1.6 mm was selected. The simulation results showed that the range of 1# ~ 3# hydraulic supports on the leeward side of the coal cutter was the best area to prevent dust from spreading to the sidewalk. The spray scheme of four groups of hydraulic supports was used, and each group had six nozzles. The vertical-horizontal combined dispersion scheme and 30° spray scheme were adopted. Besides, the distribution law of average size and concentration of droplets was revealed. After field application, the dust-reduction efficiency of the optimal scheme was 38.3% higher than that of the original scheme.

Идентификацию закона распределения результатов измерений состава и свойств нефтепродуктов проводили путем проверки сложной гипотезы с использованием пяти критериев согласия: χ2-Пирсона, Колмогорова, Смирнова, ω2 Крамера-Мизеса-Смирнова; Ω2 Андерсона-Дарлинга. В качестве возможных функций распределения вероятностей рассматривали 12 симметричных одномодальных законов распределения, а также 66 смесей этих же законов распределения. Целью идентификации являлось нахождение универсального закона распределения (смеси законов распределений) справедливого для всех рассматриваемых величин. Проверка сложной гипотезы о соответствии какому-либо симметричному одномодальному закону распределения показала, что не существует универсального закона распределения справедливого для всех методик измерений состава и свойств нефтепродуктов, наиболее часто не отвергалась гипотеза о соответствии данных обобщенному логистическому распределению, распределению Лапласа и двустороннему экспоненциальному распределению. Проверка сложной гипотезы о соответствии какой-либо смеси симметричных одномодальных законов распределения показала, что эмпирическая функция распределения результатов измерений состава и свойств нефтепродуктов может быть представлена в виде смеси двух нормальных распределений с разными значениями параметров положения и масштаба. При этом для одной и той же выборки значения достигаемого уровня значимости гипотезы о соответствии смеси законов распределений в несколько раз выше среднего значения достигаемого уровня значимости гипотезы о соответствии одному закону распределения. На основе проведенного исследования обоснована вероятностная модель процесса испытаний нефтепродуктов, в рамках которой результат испытаний нефтепродуктов рассматривается как случайная величина с функцией распределения в виде смеси нормальных законов распределения: «основного» с дисперсией, не превышающей установленные требования (при статистически управляемом состоянии процесса испытаний), и «засоряющего» с дисперсией значительно превышающей установленные требования (при статистически неуправляемом состоянии процесса испытаний). The identification of a distribution law of the results of measurements of the composition and properties of petroleum products was carried out by testing a complex hypothesis using five goodness-of-fit tests: χ2-Pearson, Kolmogorov, Smirnov, ω2Cramer-Mises-Smirnov; Ω2 Anderson-Darling. Twelve symmetric unimodal distribution laws and 66 mixtures of the same distribution laws were considered as possible probability distribution functions. The purpose of the identification was to find a universal distribution law (a mixture of distribution laws) that is valid for all considered quantities. Testing the complex hypothesis of compliance with any symmetric unimodal distribution law showed that there is no universal distribution law that is valid for all measurement techniques of the composition and properties of petroleum products; most often the hypothesis of the correspondence the data to the generalized logistic distribution, the Laplace distribution and the two-sided exponential distribution was not rejected. Testing a complex hypothesis about the correspondence of any mixture of symmetric unimodal distribution laws showed that the empirical distribution function of the results of measurements of the composition and properties of petroleum products can be represented as a mixture of two normal distributions with different values ​​of the position and scale parameters. At the same time, for the same sample, the values ​​of the achieved significance level of the hypothesis about the correspondence to the mixture of distribution laws is several times higher than the average value of the achieved significance level of the hypothesis about the correspondence to one distribution law. Based on this study, a chance model of the process of testing petroleum products was substantiated, within which the result of testing petroleum products is considered as a random variable with a distribution function in the form of a mixture of normal distribution laws: "basic" with a variance not exceeding the established requirements (with a statistically controlled state of the test process), and "fouling" with a variance significantly exceeding the established requirements (with a statistically uncontrolled state of the test process).

The gas pressure generated during a coal and gas outburst is an important factor affecting the stability of mine ventilation systems. The gas released from an outburst flows and diffuses in the mine, leading to an uneven distribution of the air in the mine ventilation system and the formation of natural wind pressure. Because of the effect of the gas pressure, the mine ventilation system becomes disordered, leading to a counter flow in the roadway. This increases the complexity of the gas movement, extends the influence range of the gas, enlarges the disaster area in the mine, and exacerbates the destructiveness. In this study, the TF1M simulation program was applied to simulate a coal and gas outburst accident that occurred in the 1747 heading roadway of the Sizhuang Coal Mine, in a bid to reproduce the entire process of the diffusion flow of the counter current and outburst gas in the mine roadway. Moreover, the dynamic influence of the gas pressure on the entire ventilation network was analyzed. An experimental device was set up to test the relationship between the natural wind pressure and the height difference of the roadway and density of the gas flow, and the formation and mechanism of the natural wind pressure were explored. By analyzing the experimental and numerical results, the variation law of the air flow and the law of gas movement under the influence of gas pressure were summarized. The movement law and influencing factors of the gas during the mine outburst period were studied, the influence range of the gas was determined, the distribution law of the gas concentration after the outburst was obtained, and further expansion of the gas was prevented. This study has theoretical and practical significance in enhancing our understanding of the development process of mine gas disasters, which can help establish effective emergency response strategies and reasonably implement postdisaster relief measures.

Extreme precipitation in summer is classified in terms of belonging to the certain baseline probability distribution. The Pareto distribution can be used as its approximation. Events deviating from the baseline distribution are represented by the largest daily total precipitation. For them, the compliance with the probability (or the average repetition time) is completely lost, that is, any anomalies can occur, but they do not exceed some limit values typical of the Arctic. Thus, for the entire set of extremes, a specific distribution law of random variables can be introduced, that describes anomalies not exceeding certain absolute values; the presence of the boundary is felt only when approaching it. For 50 analyzed years at each station in the European Arctic, approximately four such anomalies were recorded. Synoptic objects in which super-large precipitation anomalies occur are determined: these are cyclones or pressure troughs with high water vapor content in the air (exceeding $$\sim$$ 25 kg/m2) and with mesoscale systems embedded into the fronts, which are characterized by the vertical wind shear.

To figure out the distribution law of three spontaneous combustion zones in the goaf area of fully mechanized working face under high ground temperature, this study took the 11501# fully mechanized mining face of Zhujixi Coal Mine as the research object, and employed software Fluent to perform numerical simulations on the O2 concentration distribution in the goaf; then, combining with the actual situations on the site, the high-location boreholes and grout holes of the roof gas drainage roadway of the 11501# working face were selected as measuring points to measure the O2 concentration changes in a few positions such as in middle part of the goaf, on the air intake side, and on the air return side. The results show that, the numerical simulation results were basically consistent with the field measurement results, in the middle part of the goaf, the scope of the oxidation zone was 26.4m-62m; on the air intake side, the scope of the oxidation zone was 32m-96m; on the air return side, the scope of the oxidation zone was 28.4m-91m. The research findings of this paper provided a scientific reference for formulating fire-prevention and fire-extinguishing technical plans for mines.

Construction ventilation runs through the entire construction process of large underground caverns and is the key to ensuring construction progress and project safety. For the specific underground cavern group of pumped-storage power plants, a three-dimensional model is constructed, and the CFD method based on fluid mechanics theory is used to simulate the ventilation flow field of the underground cavern group. Through the comparison of the airflow in the main caverns and the air velocity distribution law, Quantitative analysis of the influence of the diameter of the ventilation shaft and the inclination of the shaft on the ventilation flow field shows that when the diameter of the ventilation shaft is 8 m and the inclination of the shaft is 80°, the ventilation effect in the underground cavern group is the best. Applying this scheme to engineering practice and conducting on-site tests, the average relative error of the measuring points is 11.32% by comparing the measured data and the simulation results, which verifies the correctness of the CFD method used. It provides reference value for studying the construction ventilation of underground caverns.

In collapsible loess area, the negative skin friction of pile foundation will cause many engineering problems such as failure of pile strength and reduction of bearing capacity of pile foundation, which will bring great harm to engineering construction. In order to study the change and distribution law of negative friction of pile foundation in collapsible loess area, the scale model test of negative friction of pile considering loess collapsibility was designed and completed. Through finite element numerical simulation, the test results are verified, and the distribution law of negative friction of pile and the number and position of neutral points are obtained. The test results show that under the condition of immersion, the loess has layered settlement, and there are both negative friction and positive friction on the pile surface, and there are two neutral points. Negative friction drags the pile downward, which makes the axial force of the pile increase obviously. The numerical simulation results verify the feasibility and validity of the test results. The research results of this paper have certain guiding significance for pile foundation design in collapsible loess area.

The wear life reliability prediction model of microwave sintered Si3N4/(W,Ti)C/Y2O3/MgO/Al2O3 composite ceramic tools based on the random distribution characteristics of hardness and fracture toughness of ceramic tool material was established. It showed that the Vickers hardness of ceramic tool materials followed a normal distribution and the fracture toughness followed a lognormal distribution. Distribution law of wear life can be determined by the joint distribution of hardness and fracture toughness. Experimental research on tool reliability of continuous dry cutting quenched high quality carbon steel T10A was carried out and the applicability of the tool reliability prediction model was verified. The results showed that the error between the theoretical reliable life and the actual life of the ceramic tool was less than 5% under the same reliability when the reliability was above 0.5.

The methane bubble plume attracts interest because it offers direct evidence of seafloor gas leakage and plays an indirect role in the exploration and identification of natural gas hydrate. In this study, based on established plume models and their migration sections, three amplitude-class attributes were extracted from three formations for the migration sections of five plumes, and the correlation between the gas content and seismic attribute was obtained. As the gas content increases, the amplitude attribute correspondingly increases, and the linear correlation is relatively good. Moreover, correlation coefficients between gas content and amplitude attributes are close to 1.0. By using linear fitting, the relation model between the gas content of the plume and the seismic attribute was obtained. The relation model was subsequently used to invert the gas content from a real data-bearing plume. Comparison of the gas content section of the plume with the attribute section and real seismic section reveals common distribution characteristics, namely, the color of the section in the lower right corner is dark. If the amplitude value is large in the seismic section of the real plume, the amplitude attribute value is also large in the corresponding attribute section, and the inverted value of the gas content is also large (because gas content and amplitude are linearly correlated), which indicates that the plume bubbles of the section in the lower right corner is intensively distributed. Finally, the obtained gas content section of the plume can reflect the distribution of the plume bubble content more simply and intuitively, from which the distribution law of seafloor bubbles can be deduced, and this lays a foundation for the further estimation of the gas content of the plume and hydrate reserves.

In order to determine the reasonable empty roof distance during roadway excavation, a mechanical model of the direct roof rock beam was established, and the relationship between the direct roof tensile stress and the empty roof distance was obtained. According to the criterion of roof stability, that is, the tensile stress of the roof does not exceed the tensile strength, the expression of the empty roof distance during the roadway excavation is determined. Taking the 150,802 roadway in Liuzhuang coal mine as the research background, the horizontal and vertical stress distribution characteristics of the direct roof under different supporting forces are analyzed, and combined with the direct roof surplus safety factor, the reasonable empty roof distance during roadway excavation is determined as 2.0 m. By using FLAC3D numerical simulation software to analyze the distribution law of vertical stress and plastic zone when the empty roof distance is 2.0 m, it is obtained that the overall stability of the roadway surrounding rock within the empty roof area is better when the empty roof distance is 2.0 m, and it is applied to Liuzhuang Coal mine 150,802 roadway. The field application results show that when the empty roof distance is selected as 2.0 m during roadway excavation, the deformation of the roof and bottom of the roadway and the two sides are small, the stability is good, and the roadway excavation speed is increased by about 30%.

Due to the insufficient understanding of the outburst mechanism, the coal and gas outburst disasters in China are more serious. Gas expansion energy is the main source of energy that causes outburst. In order to explore the distribution law of gas expansion energy in outburst coal seams, a gas-solid coupling equation of outburst coal seams was established. The distribution law of coal stress field, deformation field, gas flow field, and gas expansion energy were simulated and analyzed by using COMSOL Multiphysics. The results showed that from the excavation face to the deep part of coal seam, the stress presented unloading zone, stress concentration zone, and original stress zone. The volumetric strain and permeability reached the minimum, while the gas pressure reached the maximum at the peak value of vertical stress. As time goes on, the gas pressure in the fracture near the working face gradually decreased and was less than the pressure in coal matrix. The total gas expansion energy consists of free gas and desorption gas expansion energy. Affected by the excavation, free gas expansion energy maintained a constant value in the original coal seam and gradually decreased in the area close to the working face. The expansion energy provided by desorption gas was zero in the original coal seam. And it first increased and then decreased rapidly near the working face. Compared with stress and coal seam thickness, gas pressure and initial diffusion coefficient had significant influence on gas expansion energy of coal seam. When the diffusion coefficient was greater than 1e-9 m2/s, the gas expansion energy of the coal seam near the working face was significantly higher than that of the original coal seam, which had the risk of inducing outburst.

Gas and coal spontaneous combustion (CSC) compound disasters have become a common mode of serious accidents in coal mines. This study is aimed at revealing the characteristics of such compound disasters in the gob of Y-type ventilation fully mechanized top coal caving face with a high-level drainage roadway (HLDR) (hereafter referred to as “Y+HLDR” working face) and providing a theoretical basis for disaster prevention and control. With the W1310 fully mechanized working face of Gaohe Coal Mine taken as the research background, the distribution law of gas concentration field in the gob of the “Y+HLDR” ventilation mode under different air supply conditions was numerically simulated with the aid of COMSOL, and the area of gas and CSC compound disaster in the gob was divided quantitatively. The results show that data obtained from the field experiment coincide with the simulation results, which verifies the effectiveness of the simulation; Meanwhile, with the increase of air supply volume, the gas concentration near the working face is significantly reduced, and high-concentration gas is transferred to the deep part of the gob. The area where CSC induces gas explosions is divided by superimposing the gas and oxygen concentration fields that meet the conditions of compound disaster occurrence on the gob floor. It is concluded that the range of area with compound disaster risk is positively correlated with the air supply volume. The results of the simulation provide important theoretical guidance for the prevention and control of gob disasters.

Using the methods of field experiment, numerical simulation, and theoretical analysis, a deep concave open-pit mine (DCOM) geometric model is established. Ansys Fluent software is used to simulate the change in the temperature field at night in the DCOM over time and analyze the probability of the spatial distribution of the temperature inversion layer. The results show that the location inside the stope close to the southwest edge is more likely to present temperature inversion, and the location close to the northeast edge is the least likely to have temperature inversion, and the height range where temperature inversion is likely to occur is 100-0 m. The simulated results reveal a greater probability of temperature inversion at the closed circle (+80 m), which is consistent with that obtained by field observation. Through multiple nonlinear regression analysis, a prediction model of the spatial distribution probability of the temperature inversion layer is established, which provides a theoretical basis for the prediction and control of atmospheric pollution in the DCOMs.

The lunar surface has complex geomorphic characteristics. Since the lunar terrain entropy can reflect the amount of geomorphic information contained in the lunar terrain, this article uses the ratio of the elevation value of a local point on the lunar surface to the total elevation value of the neighborhood to calculate the local terrain entropy value of the Moon. Then, the hierarchical polishing splines algorithm is proposed to construct the digital terrain entropy model (DTEM) of the Moon, wherein the new algorithm produces a sequence of functions based on a hierarchy of coarse-to-fine control lattices to generate the modeling function, which has good modeling performance. Using the proposed algorithm, multiscale DTEMs of the Moon are constructed based on square moving windows with different sizes. From the lunar DTEMs, it can be found that the lunar terrain entropy is sensitive to the size of the square moving window and the resolution of lunar DEM, and the high-resolution lunar DTEM with suitable moving window can well show topographical variations. In addition, the lunar terrain entropy distribution models are created based on the lunar DTEMs, which is significantly important to the study of the lunar terrain entropy distribution law. Besides, two terrain parameters, i.e., surface roughness and surface slope, are selected to show that the geomorphic characteristics of the Moon can be well reflected by the lunar terrain entropy.

This paper presented a field study of the reinforced soil wall (RSW) with a geogrid wrap-around facing. In addition to the conventional monitoring content, the strain of the face-wrapping geogrid, which was neglected in most previous studies, was monitored during the construction process. The positional relationship between the maximum vertical earth pressure and horizontally laid geogrid strain was revealed by using the proposed oblique dragging effect. It was found that the strain on the face-wrapping geogrid occurred mainly in the early stage of construction. The oblique dragging effect existing in the flexible RSWs increased the vertical earth pressure and changed its distribution law, resulting in the position of the maximum vertical soil pressure appearing behind the position of the maximum horizontally laid geogrid strain. The horizontal earth pressure at different positions behind the wall was obviously lower than the theoretical result by using Rankine's theory. Also, a modified 0.3H method (where H refers to the wall height) was presented to account for the slope of the wall face, which could be used to determine the potential sliding surfaces for single-stage RSWs and two-tier RSWs with small offset.

The paper indicates that navigation in narrow waters requires navigators to use means of passage safety assessment prior to choosing a route. It is pointed out that a relevant factor when assessing the safe passage probability is the cross-track error distribution law, whose impact is the subject of the research. The article analyses recent developments and publications that have begun investigating this subject, and highlights previously unsolved parts of the general problem. The results revealed two equivalent approaches, as well as a navigational safety parameter, which are used to determine the probability of safe navigation in narrow waters on the chosen route. The need to develop advanced predictive vessel motion models is noted, while many researchers study the design of an information system for vessel motion simulation with complex dynamic models and an intelligence system for vessel motion prediction that imitates the learning process of an autonomous control unit created with the use of the artificial neural network. Methods for identification of vessel manoeuvring models are shown. Based on the analysis of vessel hydrodynamics, a nonlinear model frame of vessel manoeuvring is established. The available publications suggest using compound laws of the first and second types for describing random errors in navigation measurements as an alternative to the normal distribution law. The article examines the dependence of the safe narrow waters passage probability on the cross-track error distribution law. The normal law and compound laws of the first and second types are considered as the cross-track error distribution laws. A formula for estimating the safe passage probability in the manoeuvring area is given, and expressions for the distribution function of the normal law and compound laws of both types are obtained. To assess the impact of the cross-track error distribution law for the same route, the safe passage probability for the normal distribution law, as well as compound laws of the first and second types, was calculated. For the same route, the probability of safe passage was calculated with the use of onedimensional and two-dimensional density models. It is shown that the average relative difference between the estimated safe passage probability for both models is 0.3%, which confirms the validity of using a one-dimensional cross-track error distribution density.

To explore the influence of abandoned roadways on the technology of gob side entry retaining formed by roof cutting and pressure release, theoretical analyses, numerical simulations, and field engineering experiments are adopted to study the mining pressure distribution law, plastic zone evolution characteristics and surrounding rock control measures when the working face crosses an abandoned roadway. Mining to the vicinity of the abandoned roadway is equivalent to the process of recovering coal pillars. During the mining process, the width of the coal pillar decreases. Under the influence of mining pressure, the coal pillar will gradually lose its bearing capacity. The overburden rock gravity originally borne by the coal pillar will transfer to the retaining roadway and the coal seam in front of the abandoned roadway. Therefore, it is necessary to strengthen the support of the retaining roadway to prevent large deformations due to the sudden increase in pressure. Within 20 m near the abandoned roadway, based on the original NPR constant resistance large deformation cable (CRLD cable) support scheme, the second row of the CRLD cables is densely arranged, and the cable spacing is encrypted from 2400 to 800 mm. The successful application of these research results in actual engineering applications can provide a useful reference for working faces under similar geological condition.

The WZ oilfield is characterized by a small production range, low recovery degree, strong reservoir heterogeneity, and complex fracture distribution. At present, there is no quantitative evaluation method for fractures of different scales. This causes problems that include an unclear understanding of reservoirs’ physical properties and remaining oil distribution and seepage characteristics. In this paper, multi-scale fracture prediction and a quantitative characterization method of a fractured carbonate reservoir are studied using three-dimensional seismic imaging logging and regional tectonic stress field distribution data. On the basis of analogs, variance cube, curvature, and the Pompano through-flowline system, large-scale crack recognition is carried out. Combined with the maximum positive curvature attribute, fracture density, and fracture direction interpreted by imaging logging, a small- and medium-sized fracture model is established. Finally, the multi-scale fracture prediction is carried out. This study has important theoretical significance for accurately describing and characterizing the multi-scale fracture distribution law and guiding the fine development of oilfields.

For mountain tunnels in water-rich areas, the water pressure on the lining (WPOL) has a significant impact on the parameter selection and operation safety of the lining. Based on the theory of groundwater dynamics and complex function, this paper derives the analytical expressions of the WPOL and the seepage pressure outside the grouting ring. Under different supporting conditions, the authors analyzed how the WPOL was influenced by the head of groundwater, the permeability of the surrounding rock, and the permeability of the grouting ring. The results show that the permeability of the secondary lining not only affects the drainage capacity of the drainage system, but also greatly impacts the WPOL on the composite lining; the WPOL decreases linearly with the growing drainage capacity. To control the WPOL on the composite lining, designers of mountain tunnels in water-rich areas should carefully plan the water blocking and drainage control in accordance with the surrounding environment.

The stability of mining roadways is pivotal to safe mining in deep underground coal mines. In order to control the stability of mining roadways in deep mines, this paper studies the cooperative control effect of pressure relief and long bolt support for deep roadway under strong mining disturbance of adjacent working face in Wenjiapo Coal Mine in West China. The numerical calculation software FLAC3D was used to simulate the distribution law of the displacement, stress and plastic zone around the roadway under the disturbance of excavation and working face mining with three support schemes: “short bolt + long cable”, “long bolt + short cable”, and “long bolt + short cable + drillholes and cutting grooves pressure relief”. The results show that extending the length of bolt can ensure the supporting effect while reducing the consumption of anchor cables in the roof, and can reduce the roadway floor heave by 5.5%. Moreover, the peak lateral pressure of the roadway is reduced by 12.5%, the peak value is shifted to the depth by 6 m, and the floor heave of the roadway is reduced by 36% when the countermeasures of pressure relief in the ribs and floor are adopted. This indicates that the schemes of pressure relief and long bolt support has a significant beneficial effect on decreasing the high stress environment and controlling the deformation of roadway.

The effect of rockbolt density on fractured specimens and the distribution law of fragments were studied using the fractal method. The results show that with the increase of rockbolt density, the strength of specimens is improved. Its degree of fragmentation is increased, but the average size of fragments is decreased. The fragmentation and surface fractal dimensions are increased, their difference value is 1 in theory, but the value is slightly less than 1 in practical application due to the uncertain factors such as anisotropy of specimen. There is a positive correlation between the deformation of surrounding rock and its fractal dimension. The surface fractal dimension of surrounding rock can give a quantitative description of its degree of fragmentation and can give a comprehensive reflection to the roof stability. The support mechanism of rockblots can be understood as improving the probability of refragmentation of fragments, making its distribution gradation close to the optimal one with minimum porosity, thus reducing the deformation of surrounding rock.

Aiming at the asymmetric deformation of the surrounding rock in deep tunnels, from the perspective of the mechanical environment of the rock layer, the physical characteristics of the surrounding rock and the geometric characteristics of the tunnel, five kinds of influencing factors for the asymmetric deformation of the tunnel surrounding rock were selected, and the change levels of various factors were established. Through orthogonal test methods, 25 sets of orthogonal test simulation schemes were designed to study the asymmetric deformation law of the surrounding rock of deep roadway under the combined action of various factors. Three surface displacements of the surrounding rock are used as indicators to weigh the influence of various factors on the asymmetric deformation of the surrounding rock. Through the Extreme Difference analysis and F Statistics comparison of the indicators, the dominant influencing factors affect the deformation of the surrounding rock are obtained. By studying the distribution of the maximum deformation position of the surrounding rock, we have obtained the asymmetry characteristics of the surrounding rock deformation. In addition, the simplified mechanical analysis of the key influencing factors of the deformation of the surrounding rock is given, and the distribution law of the asymmetric characteristics of the surrounding rock deformation is summarized. The above research can provide a certain theoretical reference for the asymmetric deformation control and supporting scheme design of the surrounding rock in deep roadway.

Field tests were carried out on the compacted lateritic soil subgrade of Laibin-Mashan expressway in Guangxi Province to obtain the vertical vibration acceleration and dynamic stress amplitude of each test point under different axle loads and different driving speeds. The distribution law of the dynamic response and its frequency domain characteristics obtained by wavelet analysis emerged. The vibration of the subgrade is clearly aggravated by the increase of speed and load. Specifically, the acceleration of vehicle speed from 20 km/h to 40 km/h has a prominent effect on the vibration of subgrade, and the influence of speed on the vibration of subgrade decreases with subgrade depth. The acceleration has the greatest impact on the vibration energy in the third and fourth frequency bands.

Traditionally, mudstones are speculated to be always deposited in the still water environment. However, recent studies demonstrate the significant role of sudden events in depositing large-scale mu...

During the mining process of short distance coal seams group with high gas content, excavation of the protective coal seam will result in stress relief and fracture development which provides pathways for gas migration. Gas stored in the lower coal seam moves along the mining-induced fracture to the floor of the upper working face, which may cause the gas over-limit at the upper coal seam. This paper takes the short distance coal seams group in Xinghua coal mine as an example, theoretical analysis, numerical simulation and field monitoring are comprehensively applied to study the floor failure mechanism, pressure relief law and dynamic evolution of cracks induced by the mining of the second-right working face. The results showed that as the upper coal seam gradually advances, the pressure relief angle of roof and floor gradually decreases, and the pressure relief range and floor failure depth gradually increase. After the working face of the upper coal seam is advanced 100 m, the range of the pressure relief in the surrounding coal and rock masses approaches stable; the cracks in the shallow depth are mainly with small angles or type II shear cracks, and the cracks in the large depth are mainly shear-expansion with lager angles, and the amount of fractures in the floor reduces with the increase of the depth of the floor. It was found that the mining-induced fractures in the floor is distributed in the shape of an “O” ring, and as the working face advances, the range of this “O”-shaped crack circle keeps moving forward but the width of the crack circle is basically unchanged. Finally, the low-level drilling field was used to control the gas from lower coal seams according to the stress relief and fracture distribution law, which achieved satisfied application effect and provided guidance for mine gas extraction in similar mining conditions.

Problem Statement and purpose. For today, to solve environmental problems in the coal mining regions, studies of toxic elements (including beryllium) are obligatory and allow to determine the environmental impact of coal enterprises and coal heating enterprises. The purpose of this work is to establish regularities in the distribution of beryllium in the coal seam k5 of the mine field "Kapitalna". Data & Methods. Using Excel 2016 and Statistica 11.0 at the initial stage of the processing of primary geochemical information, the values of the main descriptive statistics were calculated, building of frequency histograms of the content and the determination of the beryllium distribution law were realized. During evaluating the relationship of beryllium with the organic or mineral part of the coal, the coefficients of affinity with the organic substance were used, which shows the ratio of the content of the elements in the coal with low and high density. Surfer 11 was used in the con­struction of all the maps. During the construction of the maps, graphs and calculation of correlation coefficients, all values of beryllium concentrations and technological parameters of coal were normalized. Results. The results of studies of the spatial distribution of beryllium in the coal bed k5 have been analyzed and areal variations of its concentrations have been established. The influence of variability of beryllium concentrations on the main technological parameters of coal was evaluated. It has been found that with the increase of mineral impurities in the coal seams the concentration of beryllium decreases, therefore, the concentrator of this element is the organic component of coal. The constructed maps are the factual basis for the long-term forecast of the concentrations of beryllium in the rock mass that extract by the mine. The calculated linear regression equations be­tween the beryllium content and the main technological parameters of coal will allow to predict its concentration in the coal seam. These equations can be used for short-term and medium-term forecasting of beryllium content in the extracted rock mass. In its turn, such forecasts should serve as the basis for technological solutions aimed at reducing its content in products and waste of coal enrichment.

With the progress in oilfield development, low-quality resources are gradually developed, and related research is focused on condensate gas reservoirs. Complex physical properties of condensate gas reservoirs and complex components of condensate gas system make well testing and productivity analysis of condensate gas reservoir difficult, which is the main reason why there has been no breakthrough in well test studies of condensate gas reservoirs for many years. In this study, based on the actual production data of the condensate gas reservoir of the Yingtai Fault Depression, we analyze the fluid phase characteristics and distribution law of the gas reservoir. Through the investigation of the preferred well test model, the well test interpretation analysis is carried out for the typical well. According to the system well test data, a one-point formula is established to predict the production capacity, and the production dynamics of the condensate gas reservoir is analyzed. This study can provide a theoretical basis for optimizing development of condensate gas reservoirs.

In order to analyze the degree of disturbance to the lining by the full-width excavation and reinforcement of the tunnel bottom, and determine the length of the excavation unit, and the excavation interval and improve the monitoring measurement plan. Through field observation and numerical simulation comparative analysis and verification, it is determined that the deformation of the lining equals mainly the deformation of the side wall, the influence range of the settlement of the side wall is greater than that of the convergence, the maximum value of the maximum principal stress of the lining is mainly distributed from the side wall of the excavation area to the arch line, the side wall of the excavation area produces shear yield when the length of the excavation unit reaches 5m, and the influence area will cross influence when the excavation interval is less than twice the influence area. Based on the distribution law of lining deformation, principal stress and elastoplastic area, it is recommended that the length of the excavation unit should be less than 5m, the excavation interval should be greater than twice the influence range of the side wall settlement; and the monitoring section should be arranged at the central section of the excavation area, the interval of the monitoring section should be determined according to the location of the excavation unit, the monitoring scope may not extend to the unreinforced section, and the settlement of the side walls should be increased.

In the loading and failure process of the coal and rock medium, with the increasing of the damaging and failure extent, the medium state gradually changed from the continuous, the quasicontinuous, and the discontinuous to the loose successively. To evaluate the damaging failure extent of the coal and rock mass and distinguish the state of the coal and rock mass medium, first, the medium state index was defined based on the acoustic wave propagation model. Then, based on the coal mass in the working face 8512 in the Chenjiagou Coal Mine in China, the acoustic character and the mechanical character experiments were conducted. Through experiments, the variation law of the ultrasonic wave velocity and the medium state index of the coal mass with the strain under the compressive state were acquired; with the increasing of the strain, the medium state indexes successively experienced the variation process including stabilising around 0, slow increasing, dramatic increasing, and stabilising around 1. Then, based on the variation law of the medium state index, the coal and rock mass medium state judgement model was constructed. This model was applied to judge the coal mass medium state. After it, the mudstones in the roof of the same working face were regarded as the research object, the mudstone medium state was divided into 4 types according to the medium state judgement model, namely, continuous, quasicontinuous, discontinuous, and bulk solid, and the mudstone failure state was basically consistent with the continuous, quasicontinuous, discontinuous, and bulk solid state. The adaptability and rationality of the judgement model was verified. Finally, engineering application of the judgement model was conducted. The distribution law of the top coal with different medium state was acquired. In the top coal that was 186 m away from the working face, it belonged to the continuous medium state. As for the top coal that was 6 m to 186 m far away from the working face, it was under the quasicontinuous medium state. For the top coal that was 3 m to 6 m far away from the working face, it was under the discontinuous medium state. For the top coal that was less than 3 m far away from the working face and behind the working face, it belonged to the bulk solid medium state. The state judgement model can successfully distinguish the medium state of the coal seam and mudstones in the roof in the working face 8512. This provided a new approach to evaluate the damaging failure extent of the coal and rock medium in the Chenjiagou Coal Mine.

Firmness is one of the most important physical properties of rock, and indicates the rock’s ability to resist damage. It has considerable relevance to mining, blasting, tunneling, construction, and other engineering fields. In this study, the fractal particle-size-distribution theory was used to calculate the surface areas of coal particles after impact crushing. Combining the surface area with the energy input, a new index, fs, that can characterize the surface energy consumption was established. A total of 84 groups of impact crushing experiments were conducted on six samples from different coal mines, and their fs values were obtained. The effects of different initial particle sizes and impact numbers on fs were discussed. To verify the rationality of the fs approach, the tensile strengths of 900 particles were tested via single-particle uniaxial compression, and the strength distribution law was determined. The results show that there are significant linear positive correlations between both the tensile strength and modified Protodyakonov coefficient of coal and fs, indicating that fs can be used to evaluate rock firmness. This new index is of considerable significance to risk assessment of coal and gas outbursts, and is expected to be widely applied for firmness measurement of drilling cuttings and soft rocks.

Gob-side entry retaining (GER) has been widely used around the world. However, when the technology of gob-side filling and roadway retaining is applied to the mining of three-soft thick coal seam, large deformation of surrounding rock and failure of support structure are still unavoidable, especially the floor heave deformation, even the closure of the roadway section in serious cases. Taking 16,011 working face of Zhaogu No. 1 Coal Mine as the research object, mineral composition analysis showed that there are a lot of clay minerals in the surrounding rock, which shows strong swelling characteristics. The mechanical model of the overlying strata with long cantilever structure was constructed to explain the process of ground pressure transferring from two sides of roadway to the floor after retaining roadway, and then the variation and distribution law of stress on both sides of the floor with the working face promotion was obtained. With the aid of uncoupling support theory, this paper analyzed the floor heave mechanism of GER in three-soft thick coal seam, and pointed out that shear staggered floor heave was the main cause of floor heave deformation. Based on above analysis of large deformation mechanism of GER, the three-level control technology of surrounding rock in entry retaining in three-soft thick coal seam was put forward: directional pre-splitting decompression technology, constant resistance & large deformation anchor cable (CRLDAC) roof support technology and floor deformation control technology. The key parameters of the three-level control technology were determined by field industrial test. Monitoring data proved that the three-level control technology can effectively control the deformation of surrounding rock in retained roadway, in which roof-to-floor convergence had been reduced by 58%, and floor heave had been reduced by 65%, finally, the roadway had been retained successfully.

In this paper, an assessment method of excavation disturbance effect is proposed by using distributed optical-fiber strain sensing technique. Model tests of trenchless construction under different parameter conditions are carried out in the laboratory. In the test, the excavation was simulated by using the deflate of pre-burying air bag, soil displacement is measured by settlement mark, at the same time, The soil strain of overburden layer is obtained based on Brillouin Optical Time-Domain Analysis (BOTDA). Through the analysis of the experimental data, the partition theory of excavation disturbance zone is proved and verified through test data. The correlation between ground settlement and soil strain distribution due to trenchless construction are compared and analyzed. The mechanical response of overlying pavement are further discussed. Research results indicate that soil strain of overburden layer is symmetrically distributed about the excavation surface, which is compressed near the centerline and tensioned on both sides due to the excavation disturbance impact. The width of excavation disturbance zone derived from the test data shows good accordance with the calculation results based on the partition theory, the maximum error is less than 10%. A certain consistency exists between the distribution law of strain curve and settlement trough. Due to the uneven distribution of support force caused by foundation settlement, the pavement model shows notable bending deflection after trenchless excavation, and the maximum increment ratio of support force exceed 50%. The combined impact of ground traffic load and excavation disturbance is considered to be more unfavorable to the safety of pavement structure. The conclusions can be suggestive and helpful to trenchless excavation control.

A finite element model is presented which simulates the tunnel construction process, and deformation and stress characteristics, in the surrounding rock during its operation stage. The pore water pressure and distribution law of leakage in the surrounding rock are calculated by considering the effect of groundwater. The results show that during the process of excavation, the surrounding rock undergoes a small degree of stress relief, and relatively low tensile stresses appear locally at the bottom of tunnel vaults and inverts. As tunnel leakage decreases, there is a time-dependent decrease in pore water pressure. However, stress in the supporting structures increases, and displacement and deformation in the surrounding rock increases as leakage continues.

The mud film thickness on the outer surface of casing and its distribution laws are important factors affecting the cementation quality at casing–cement interfaces. So far, however, the distribution laws of mud film thickness on the outer surface of casing at different inclinations and its effect on the interfacial cementing strength have never been reported in literatures. In this paper, the mud film thickness at different parts on the outer surface of simulated casing (steel pipe) was measured at the inclination of 0°, 30°, 60° and 86°, respectively, using the independently designed experimental device. Then, the distribution law of mud film thickness on the outer surface of casing and its effect on the interfacial cementing strength were summarized. And the following research results were obtained. First, when the inclination increases from 0° to 86°, the mud film thickness changes from uniform distribution to thin-and-thick distribution, and the area proportions of thinner and thicker mud films both increase. And especially at the inclination of 86°, the mud film thickness on the upper surface is very large, and there are large exposed areas on the left and right surfaces of the steel pipe. Second, the cementing strength at the casing–cement interface of the exposed casing is much higher than that at the interface with mud film. And with the increase of inclination, the interfacial cementing strength with mud film tends to increase. Third, with the increase of inclination, the interfacial cementing strength increases successively, which is closely related to the area proportion of the exposed steel pipe to the solid mud film on the outer surface. In conclusion, the exposed area of the simulated casing on the outer surface is a key factor affecting its interfacial cementing strength. Keywords: Casing–cement interface, Inclination, Mud film thickness, Distribution law, Cementing strength, Exposed outer surface of casing

This paper establishes an analytical model to study the influence mechanism of hydraulic fracturing around vertical wellbores under the unsteady seepage in hydrocarbon reservoirs, deduces the analytical solution of water pressure and hydraulic gradient of the model, and compares the law of water pressure and hydraulic gradient changing with time with the results of numerical simulation. The results confirm the accuracy of these analytical solutions. The variation laws of water pressure and hydraulic gradient in the sample under unsteady seepage are analysed by using the COMSOL Multiphysics software. The results show that: the increasing rate and amplitude of water pressure decrease with the distance of water inlet, however, hydraulic gradient near the water inlet is the largest and decreasing with the distance. In order to better understand the mechanism of hydraulic fracturing of rock mass, we studied the influence of permeability and water injection pressure on water pressure and hydraulic gradient of rock mass. The results show that: large permeability coefficient and high hydraulic gradient will increase the probability of rock mass hydraulic fracturing. The permeability and hydraulic gradient of rock mass is important factor in determining whether the rock has hydraulic fracturing. The distribution law of water pressure and hydraulic gradient in rock mass under unsteady seepage provides important reference and basis in hydrogen developing reservoirs.

Through the geochemical analysis of two hundred-meters cores KD4 and ZK3 from Laizhou Bay, in this study, we determined the distribution law and controlling factors of the geochemical elements. We analyzed 24 elements with respect to their R factors and major principal components, which were combined with the source discrimination functions DFCr/Th and DFCa/Al to obtain the sediment source index and its variation with depth for this area. A comparison of the changes in climate indicators suggests a clear correlation between the source and climate changes. The results show that the Yellow River and surrounding short-term rivers are the main sediment sources in this area. The PC3 of the KD4 core and PC2 of the ZK3 core (e.g., CaO, MnO, SiO2) exhibit significant variations and reflect the relative contributions of Yellow River sources. The deposition process can be divided into six stages: in Phase I (MIS 5c-MIS 5a), the Yellow River formed, and the composition of the Yellow River had a greater influence on the sedimentary composition of the study area. In Phase II (MIS 5a-MIS 3), the sediment sources of the Yellow River and the short-term streams in this area were wavering, with the sediments derived from short-term rivers playing a more important role. In Phase III (MIS 3), with a sharp drop in temperature, the study area was in the process of retreat, and the sediment source changed from the Yellow River to short-term rivers, after which the Yellow River source material remained the main sediment source for the region. A similar process occurred three more times in Phase IV (MIS 3-MIS 2), Phase V (MIS 2-MIS 1), and Phase VI (MIS 1). With changes in climate, especially during alternating sea-land phases, the sediment source varied in marine-terrestrial-marine phases, and the changes are observed as Yellow River source-surrounding provenance-Yellow River source. However, this process of change is not synchronized with the sea-land strata alternation.

A comprehensive assessment of the effectiveness of heavy-haul traffic is a prerequisite for its implementation in world railway sector. The assessment should include the study of the effect of increased axial loads on degradation of the elements of the track’s superstructure, deformation parameters of the ballast layer and the track’s substructure, and of measures intended to reinforce the railway infrastructure accordingly. It is necessary to consider rather accurately the force factors acting on the track and generated by different types of rolling stock with various axial loads. The distribution of force factors for a specific section of a railway track is a multifactorial process, the quantitative parameters of which depend on the structure of the train traffic flow, the type of rolling stock and its share in the total daily train traffic passing through this section, speed limits set for the section, track profile (straight line, curve), technical conditions of rolling stock and elements of the track superstructure.The objective of the work was to develop a technique for determining the integral law of distribution of vertical and lateral forces affecting the track and caused by wheels of different types of rolling stock, depending on the share of the operation of the respective types of rolling stock in the daily train traffic flow. Methods of mathematical statistics were used.In the process of experimental studies of the effects of various types of rolling stock, the statistical distributions of vertical and lateral forces have been determined. The histograms of vertical and lateral forces have been approximated by theoretical laws. Kolmogorov–Smirnov fit criterion has been used to confirm goodness of chosen approximation functions. A technique has been developed for mixed freight and passenger railway traffic that allows to consider the contribution of the share of each type of rolling stock in the force impact on the track when calculating the total impact. The technique is based on real, experimentally established distributions of vertical and lateral forces, traffic speed at the considered section of the track with regard to seasonality (winter, summer), and can be used for the sections where heavyhaul traffic is being implemented.

In production and scientific research, the research on the characteristics of submicron particles has attracted extensive attention, which is of great significance to the development of industrial production, medical and health inspection and other fields. In this paper, the characteristics of submicron particles are studied based on backlight scattering. By collecting the real-time waveform of the backscattering signal of particles with different particle sizes at different concentrations, the corresponding relationship between the particle concentration and the number of pulses was obtained. It is found that the peak value of the backscattered light energy has a good linear relationship with the particle size. The analysis of the signal distribution law of standard particle swarm with different particle size parameters found that it conformed to the lognormal distribution form.