As a core safety component in the hydraulic system of CNC stretching pads, the safety locking valve undertakes precise stamping position maintenance and emergency braking protection; its performance dictates the hydraulic system’s operational stability. Existing ones induce hydraulic oil volume dynamic changes during opening/closing, significantly affecting blank holder force control. To solve this, its structure is innovatively optimized. Based on the CFD method, a dynamic calculation framework integrating unsteady flow characteristics and structural motion characteristics has been constructed, realizing accurate simulation research on the dynamic characteristics of the safety locking valve. Through simulation analysis, the distribution law of the internal flow field during the transient opening and closing process of the locking valve has been thoroughly explored, the distribution mechanism of the transient flow field has been systematically revealed, and finally, the fluid regulation characteristic parameters of the safety locking valve have been obtained, providing an important theoretical basis for subsequent engineering applications.

Abstract Gliding arc air plasma exhibits significant application potential in energy, environmental protection, and other fields due to its non-equilibrium characteristics (high electron temperature and high concentration of reactive species). However, the spatial distribution characteristics of its electron temperature and electron density play a crucial role in determining plasma chemical efficiency. In this study, a multi-spectral imaging method combined with a collisional-radiative model was employed to conduct high-resolution spatial distribution diagnosis of the high-energy electron temperature and electron density of air gliding arc plasma, and the influence law of gas flow rate on plasma parameters was analyzed. The experimental results show that the electron temperature in the plasma core region can reach 4 eV, and the electron density is on the order of 10¹⁴-10¹⁵ cm⁻³, with significant spatial inhomogeneity. By adjusting the gas flow rate of the gliding arc generator, the distribution law of electron parameters in the gliding arc plasma generator can be significantly changed. The research results can provide important data support for optimizing the design of gliding arc plasma reactors and promoting their industrial applications, meanwhile, this diagnostic method may achieve effective parameter distribution monitoring in the industrial application of gliding arc plasma.

Slow earthquakes differ from regular earthquakes in their slower moment release and size distribution dominated by smaller events. However, the physical origin of these slow earthquake statistics remains controversial. In this work, we experimentally demonstrate that their characteristics emerge from low-friction soft granular shear. To model slow-earthquake fault materials under hydrothermal conditions, we use a low-friction soft hydrogel particle layer floating on lubricating fluid and conduct stick-slip experiments. The observed slip events follow the same laws of both moment release rate and size distribution as with slow earthquakes, contrasting with frictional rigid granular shear. Slip size is determined by the competing effects of shear localization and pressure enhancement with decreasing porosity. These findings indicate that low friction and particle softness in sheared granular systems with sparse contact structures cause slow earthquake statistics, which may be driven by pore fluid dynamics and shear localization within hazardous fault zones.

Experimental study on pore distribution and compression-shear failure law of coal pillar dam specimens under wet-dry cycles

With the constant aging of marine vessels, it is becoming increasingly difficult to ensure their navigational safety. Despite the efforts being made, the human factor remains the main cause of accidents in marine and river waters. The necessity of considering the process of keeping a running watch as a system including appropriate subsystems is substantiated. The system of navigation watchkeeping, which includes a subsystem of self-control of the human factor, is being investigated. A model of the information transformation system in ship safety management has been compiled, including a subsystem of self-monitoring. It is noted that the process of information transformation in ship condition management with self-monitoring is capable of ensuring an effective state of safety of the ship, crew and cargo. The assumption is introduced that the recovery time of the subsystem of self-control of the human factor is subject to a degenerate distribution law with a certain mathematical expectation, which will significantly simplify the calculation formulas and create convenient methods for assessing and ensuring reliability (safety) in the navigation watch system. The probability of trouble-free operation of the watchkeeping system is investigated in the case of a degenerate law of the recovery time distribution of the subsystem of self-control of the human factor and in the case when the law of the recovery time distribution is different from the degenerate one. The probability of error-free transformation of information, taking into account self-control, is estimated. The maximum error value in calculating the probability of trouble-free operation of the information conversion system in control is calculated when replacing any law of the distribution of the recovery time of self-control with a degenerate distribution law. An experimental assessment was made of the probability of reliable operation of the navigation watch system under the exponential law of the recovery time distribution of the self-monitoring subsystem.

Compared to traditional long-wall mining, the gob-side entry retaining by roof-cutting (GERRC) technology reduces the amount of entry excavation by 50%, and recovers the previously wasted coal pillar resources, which has obvious superiority in mining efficiency and economic benefits. In response to the problem of reasonable entry location of the GERRC in close-distance coal seams, this paper takes the 9105 Working face in Longmenta Coal Mine as the engineering background and conducts an in-depth study by using methods such as theoretical analysis, numerical simulation and field tests. Firstly, the structural characteristics of the overburden rock for GERRC in the close-distance coal seam are analyzed, based on which a method for determining the reasonable location of the GERRC in close-distance coal seams is proposed; secondly, a mechanical model for load transfer and rock mass damage of the upper coal seam floor was established to analyze the floor damage characteristics and stress distribution law, forming the theoretical analysis of the reasonable entry location; Finally, the optimal entry location (22.5 m from the center of the upper remaining coal pillar) was used for field test of GERRC at the 9105 Working face of Longmenta Coal Mine. It has achieved good on-site application results.

This paper investigates vertex processes of the convex hull generated by inhomogeneous Poisson point processes within a parabola in the plane. Using distribution laws and the conditional distribution of the vertex processes, a stationary Markov process is constructed to find an exact expression for the mathematical expectation of the part of the perimeter between the initial vertices of the convex hull.

To study the gas distribution law in the goaf of low-permeability and extra-thick coal seam comprehensive mining working face, Fluent simulation software is used to numerically simulate the gas distribution law of the goaf in the east 102 working face of the mine. The results show that under the comprehensive mining conditions of the U-shaped upwind ventilation working face, the high concentration gas in the deep part of the goaf accumulates on the return air side, forming a gas-rich area, with the highest gas concentration reaching 70%. The simulation results are basically consistent with the field measurement data, providing important theoretical support for the implementation of gas extraction measures in the goaf.

ABSTRACT Aiming at the problems of airlock, reduced pumping efficiency and equipment wear caused by the high gas-to-liquid ratio in the process of carbon dioxide oil driving, this paper designs an active suction-assisted lifting short connection. Through indoor experiments and simulations, the flow velocity distribution law inside the short-joint was studied, and it was found that increasing the throat length and the distance between the inlet and the nozzle would reduce the fluid velocity, and the optimal length-to-diameter ratio of the diffusion tube was 1:7. The experiments showed that, when the liquid volume was greater than 0.194 m3/h, the inlet gas was continuous, and the gas-liquid volume was approximately linearly correlated. After applying the gas inlet pressure, the gas-liquid volume increases with the increase of pressure, but the gas-liquid ratio increases and the liquid-carrying rate decreases, which is especially obvious when the pressure exceeds 0.4 MPa. When the gas volume is 0–6.86 L/min, the liquid-carrying rate decreases rapidly and stabilizes after exceeding 6.86 L/min, and the flow pattern in the tube is always segmental plug flow. This design is of great significance for utilizing formation gas energy, coping with wells with high gas-liquid ratio and improving well production.

ABSTRACT We study how expanding alcohol availability at grocery and convenience stores affects consumer traffic in liquor stores by leveraging recent changes in state‐level alcohol distribution laws in a difference‐in‐difference quasi‐experimental design. Results indicate that more extensive liberalization results in higher losses of traffic at liquor stores and that the impact is dynamic over time. Additionally, the overall impact at rural stores is larger compared to urban stores. We discuss the economic, geographic, and behavioral factors behind the heterogeneous impacts of the policy and develop a general theory of the effects of liberalization on the liquor store sector.

ABSTRACT Accumulated debris may block post‐earthquake roads and severely impact evacuation, emergency and recovery operations. It is of great importance to investigate the distribution laws of building debris. In this study, a probabilistic prediction model for post‐earthquake debris extent and road blockage fragility estimation, conditioned on the intensity measurement of earthquakes, is presented. The main contributions of this paper are (1) highlighting the random distribution characteristics for post‐earthquake debris extent including maximum debris width, debris length and debris area; (2) establishing an unbiased probabilistic prediction model for debris width and length based on the Bayes theorem with accumulated blocks from both the out‐of‐plane failure of infill walls and collapsed buildings; (3) developing a blockage fragility estimation method for post‐earthquake road networks versus the intensities of earthquakes with Monte‐Carlo simulation; and (4) achieving better applicability and less uncertainty for this presented model than those established with satellite images after an earthquake event. Finally, four buildings constructed as reinforced concrete frame (RCF) structures are used to generate a virtual debris extent data pool for developing the prediction model. The numerical results indicate considerable variability in the debris extent, with a coefficient of variation (COV) ranging from 3.0% to 18%. Earthquake intensity significantly affects the debris extent. Furthermore, the scenarios in which the road centerline is open or not open substantially affect the conditional blockage probability of the post‐earthquake road network. This method is beneficial for designing rescue routes and evacuation plans for earthquake events.

A complex operating environment and high operating temperature lead to the uneven temperature field distribution of key components of the molten salt Linear Fresnel collector in a way that compromises the collector’s safety and stability. To investigate the influence of different working conditions on the temperature field of the molten salt Linear Fresnel collector under multi-physical field conditions, this study develops a three-dimensional numerical model based on ANSYS that integrates the loading of solar radiation and thermal–fluid coupling, compares and verifies the accuracy of the model through the collector field data of the actual operation, and systematically analyzes the distribution characteristics of the receiver tube and outlet temperature field and its rule of change. The results show that temperatures of the receiver tube and exit during operation exhibit pronounced non-uniform distribution characteristics, in which the inlet flow rate of the molten salt and intensity of solar irradiation have the most critical influence on the temperature distribution throughout the receiver tube and its exit, and the heat transfer temperature difference between the molten salt and heat conduit wall is reduced as the inlet temperature raises, which makes the receiver tube and molten salt outlet temperature gradient slightly reduced. This study not only supplements and improves the numerical simulation study of the molten salt Linear Fresnel collector under complex working conditions but also reveals the distribution law of the temperature field between the receiver tube and the outlet, which provides adequate numerical support for the safe and stable operation of the collector.

Modes and ecological damage effects of internal erosion of the redbeds.

The results of studies of the ecological and biological state of the Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) in the conditions of the city of Chita are presented. The author has performed a diagnosis of the vital condition of Quercus mongolica and assessed the sustainability for Chita from 2021 to 2024. In the green spaces of the city, Q. mongolica practically does not grow. The largest number of plants was observed in the indoor landscaping. According to the indicator of absolute occurrence, Q. mongolica belongs to the group of rarely occurring species. An analysis of changes in the life status of Q. mongolica within the surveyed urban populations showed that a normal or close to it distribution law with a maximum frequency of occurrence is characteristic. The limits of variation correspond to two or three categories of vitality with a minimum condition index value of 2.0. This characterizes Q. mongolica as a potentially tolerant species for Chita.

Judging from the current global exploration trend, ultra-deep layers have become the main battlefield for energy exploration. China has made great progress in the ultra-deep field in recent decades, with the Tarim Basin and Sichuan Basin as the focus of exploration. The Sichuan Basin is a large superimposed gas-bearing basin that has experienced multiple tectonic movements and has developed multiple sets of reservoir–caprock combinations vertically. Notably, the multi-stage platform margin belt-type reservoirs of the Sinian–Lower Paleozoic exhibit inherited and superimposed development. Source rocks from the Qiongzhusi, Doushantuo, and Maidiping formations are located in close proximity to reservoirs, creating a complex hydrocarbon supply system, resulting in vertical and lateral migration paths. The structural faults connect the source and reservoir, and the source–reservoir–caprock combination is complete, with huge exploration potential. At the same time, the ultra-deep carbonate rock structure in the basin is weakly deformed, the ancient closures are well preserved, and the ancient oil reservoirs are cracked into gas reservoirs in situ, with little loss, which is conducive to the large-scale accumulation of natural gas. Since the Nvji well produced 18,500 cubic meters of gas per day in 1979, the study of ultra-deep layers in the Sichuan Basin has begun. Subsequently, further achievements have been made in the Guanji, Jiulongshan, Longgang, Shuangyushi, Wutan and Penglai gas fields. Since 2000, two trillion cubic meters of exploration areas have been discovered, with huge exploration potential, which is an important area for increasing production by trillion cubic meters in the future. Faced with the ultra-deep high-temperature and high-pressure geological environment and the complex geological conditions formed by multi-stage superimposed tectonic movements, how do we understand the special geological environment of ultra-deep layers? What geological processes have the generation, migration and enrichment of ultra-deep hydrocarbons experienced? What are the laws of distribution of ultra-deep oil and gas reservoirs? Based on the major achievements and important discoveries made in ultra-deep oil and gas exploration in recent years, this paper discusses the formation and enrichment status of ultra-deep oil and gas reservoirs in the Sichuan Basin from the perspective of basin structure, source rocks, reservoirs, caprocks, closures and preservation conditions, and provides support for the optimization of favorable exploration areas in the future.

In response to the problem of low bearing capacity of soft coal support in deep mining, which leads to deformation and instability of composite roof, a comprehensive analysis of coal support stability was conducted through on-site research, mechanical analysis, numerical simulation, and in-situ testing methods. Based on the theory of elastic-plastic deformation, a mechanical analysis model for coal seam interface is constructed, and analytical expressions for the stress and width of the coal seam interface in the limit equilibrium zone of the coal seam are derived. The distribution law of the stress and width of the coal seam interface in the limit equilibrium zone under different variables is analyzed. On this basis, based on the deformation and failure characteristics of coal support, a key part mutual stability principle based on "strengthening the rib to consolidate the roof and strengthening the roof to protect the rib" is proposed. Field tests show that the support scheme can ensure the strong support of the roadway foundation, achieve micro disturbance of the roof, and ensure the safe and effective use of the roadway during service.

The article substantiates the relevance of processing statistical data on natural processes that lead to emergencies and negatively affect the environmental situation. Informationis provided on determining the consistency of samples of random variables of parameters of such processes according to known distribution laws using the Pearson and Kolmogorov criteria, as wellas the consistency of estimates and coefficients of variation, asymmetry and kurtosis of a sampleof random variables and the distribution law. It is shown that the β-distribution of the 1-st kind canbe accepted as a universal approximating law and analytical expressions can be derived to find its parameters. Using the examples of statistics on the average annual water consumption in the riverand the energy parameters of seismic events, analytical expressions are derived for the corresponding probability densities of β-distributions of the 1-st kind. The probabilities of the occurrence of negative events are estimated based on the thresholds of the average annual water consumption and the energy parameter of seismic events, respectively. The conclusion is made about the possibility of effective use of the β-distribution of the 1-st kind for the analysis of statistical data of a wide class of natural and man-made processes.

Abstract. Existing research on tooth surface wear of helical gears has insufficiently considered the complex and variable lubrication conditions between meshing tooth surfaces. This study constructed a mixed elastohydrodynamic lubrication (EHL) model based on the meshing characteristics of helical gears, analyzed the lubrication characteristics between the meshing tooth surfaces and the temperature changes induced by asperity contact and oil film shear, and introduced them into the improved Archard wear model to construct the surface wear calculation model under the mixed EHL conditions. Taking the changes in meshing characteristics of tooth profile during the tooth surface wear accumulation process as a connecting bridge, the mutual influence relationships among the tooth surface wear, lubrication characteristics, and tooth surface temperature rise were systematically clarified. The cumulative distribution law of tooth surface wear and the influence of tooth surface roughness, working conditions, and tooth profile parameters on the tooth surface wear depth were explored. The research indicates that the wear depth at the tooth root and top is deeper than that at the pitch position, the pinion's surface wear depth is greater than that of the gear, and the maximum wear appears at the pinion's tooth root. The wear depth under mixed EHL conditions is nearly 4 orders of magnitude lower than that under dry friction conditions. Reducing the magnitude of tooth surface roughness can effectively decrease the tooth surface wear depth. Appropriately increasing the velocity, module, tooth width, helix angle and tooth surface hardness is beneficial to improving the anti-wear ability of tooth surfaces. This study can provide a reliable theoretical basis for predicting and optimizing the tooth surface wear of helical gears under complex lubrication conditions.

In suspension bridges employing spatial cables, the main cables undergo torsion during the construction process. Clarifying the distribution pattern of the main cable torsional angle can guide the positioning and installation of cable clamps and mitigate issues such as wire waving. This paper provides a theoretical calculation method for the distribution law of the torsion angle of the main cable. Firstly, it is assumed that the load form that causes the torsion of the main cable is the uniform load along the cable length and the span length. The theoretical calculation formulas of the torsion angle are derived, respectively, and the two formulas are compared. Analysis shows that under a uniformly distributed load, when the main cable is deflected at a certain angle, the torque is non-uniformly distributed along the cable, and the torsional angle follows a fourth-order parabolic curve along the span. A model test on spatial cable deflection was conducted, and the measured torsional angles were compared with theoretical results. The findings indicate that the measured torsional angle variation along the span is generally consistent with theoretical calculations. When the deflection angle of the spatial cable is large, the theoretical value exceeds the measured value. Furthermore, a finite element model was employed to calculate the torsional angle, torque, and bending moment during cable deflection. The results reveal that the distribution of the torsional angle depends on the ratio of the moment of inertia and the polar moment of inertia of the main cable section. The smaller the polar moment of inertia relative to the moment of inertia, the closer the torsional angle is to the spatial deflection angle. When the polar moment of inertia is relatively small, except in the end regions, the distribution of torque obtained from simulations is largely consistent with the theoretical values.

Abstract The Hertz theory's reliance on static equilibrium assumptions limits its applicability to dynamic scenarios. This article addresses the gap regarding the dynamic normal stress at the contact interface between a rigid sphere and an elastic half-space. Based on the physical characteristics of dynamic contact and the mass point dynamics theory, the dynamic equations of the interface mass point are established. By decoupling these equations based on the lateral and tangential motion of the mass point, we derive a unified normal motion equation that describes the relationship between the normal strain of each mass point and the collision center point. The equation demonstrates that the lateral and tangential strains prior to collision do not directly affect the sphere motion in the normal direction, while the incremental lateral and tangential strains after post-collision significantly do. The lateral stress increment, tangential stress increment, and the distribution law of normal stress for each mass point at the interface are obtained. The results demonstrate that the relative relationship between the maximum deformation depth in the non-contact area and that in the contact area, as well as the relative relationship between the anisotropic stress of the contact area and the normal stress at the collision center, are consistent with the results determined by Hertz theory, but the obtained normal stress value is significantly greater than that determined by Hertz theory. The detailed discrepancies have been compared. The findings have implications for understanding and predicting contact interface failure in engineering applications, particularly under dynamic loading conditions.