Pressure Balance Research Articles

DEVELOPMENT OF AN EXPRESS ASSESSMENT OF THE RESULTS OF GEOLOGICAL AND TECHNICAL MEASURES TAKEN INTO ACCOUNT OF THE GATHERING SYSTEM

This article provides a rationale for the method of «express» assessment of changes in well flow rate when performing geological and technical measures in an oil field. In view of the cluster configuration of wells that is widespread in Western Siberia, the author identifies two groups of well pads, one of which is influencing, the other is reacting. At the influencing well clusters, as a result of the implementation of geological and technical measures to increase extraction from the productive formation, an increase in the produced fluid occurs. This leads to destabilization of the equilibrium in the “reservoir – well – pipeline” system. The consequence of a violation of this balance is an increase in the load on the reservoir fluid pumped in oil and gas gathering pipelines on individual branches of the field collection system. This leads to a redistribution of wellhead pressures at production wells, which, in turn, also leads to a change in bottomhole pressure and a change in well productivity. The author defines well pads where there is no increase in production, but where there is a change in pressure at the wellheads as reactive. With an increase in linear pressure on the pads, the energy balance in the operating production wells at the reacting well pads shifts towards a decrease in flow rate. Conversely, when wellhead pressure decreases, well productivity increases. These parameters will change until the energy balance of pressures in the wells is achieved. In connection with the above, within the framework of this work, an approach is presented for assessing changes in well operating parameters with increasing production in the field. An example of testing the proposed approach on a complex integrated model is given. To test this approach for adequacy, a comparison was made of theoretical calculations of changes in the operation of real wells with calculations performed on a customized complex integrated model of an oil field. It is worth noting that this type of calculation is characterized as approximate. Its use is advisable exclusively at the stage of preparing programs for performing geological and technical measures to determine reservoir zones in which the negative effect of increasing production will be minimal.

Comparative study of magnetic field effect on fast plasma flow of heavy and light species investigated by spectroscopic measurement

To understand the effects of magnetic fields on the propagating plasma flows of heavy and light ion species, a laboratory-scale experiment was conducted using a pulsed-power discharge. The plasma drift velocity and electron temperature were estimated by time-of-flight and line-pair methods, respectively, using spectroscopic measurements. Ion current waveforms were measured using an ion collector. When a magnetic field was applied, the plasma drift velocity decreased and the electron temperature increased in both heavy and light plasmas. The magnetic Reynolds number, pressure balance between the plasma and magnetic field, and ion current waveforms show that heavy plasma has a high possibility of deforming the magnetic field and generating accelerated ions through interaction with the magnetic field.

Total Magnetic Field Perturbations at Martian Low Altitudes (≤500 km): MAVEN Observations in 2014–2023

AbstractMagnetic perturbations in the Martian ionosphere are often considered as representing plasma irregularities, but thorough statistical comparisons between the two independent phenomena have been rarely conducted. In this study, we investigate the statistical relationship between total magnetic field perturbations and those of O2+ density as observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft at altitudes below 500 km in 2014–2023. From the 1 Hz time series of magnetic field strength, perturbation intensity is estimated by subtracting a signal smoothed with a Savitzky‐Golay filter (window size ∼36 km). Statistically, the magnetic perturbations are stronger on the dayside than at night, in the local summer hemisphere than in winter, and away from crustal magnetic anomalies than nearby. Also, day‐to‐day variability of the magnetic perturbations exhibits a weak but significant correlation with that of solar wind electron density. The statistical behavior of total magnetic field perturbations is not the same as that of O2+ density perturbations: that is, the former is not a perfect proxy for the latter. The seemingly counter‐intuitive discrepancy can be explained by effects of inhomogeneous background magnetic field strength (participating in total pressure balance across plasma perturbations) and localized ionospheric currents at altitudes unreachable by MAVEN.

Influence of N2 admixture on mode transition of discharge in N2–Ar helicon plasma

Effects of N2 admixture on multiple wave modes and transitions were investigated in N2–Ar helicon plasma under fixed input power and magnetic field. The structures of helicon waves were measured by a B-dot probe to verify the different eigenmodes. The experimental results show that the plasma morphology, emission spectrum, and spatial profile change significantly during mode transitions with the N2–Ar ratio. The calculated results from the pressure balance model indicate that the densities of species N2, N+, Ar, and Ar+ will change largely during mode transition around some specific N2 percentages, which will help to improve the application of N2–Ar helicon plasma in material processing greatly.

Experiments on Steam-Assisted Gravity Drainage with Coinjection of Noncondensable Gases during the Middle and Later Stages of Its Development in Super-Heavy Oil Reservoirs

Summary The problems of oil/steam ratio (OSR) and oil production decline are prominent during the middle/later stages of steam-assisted gravity drainage (SAGD) in superheavy oil reservoirs. Using noncondensable gas (NCG) by SAGD can reduce heat loss to the overburden and reduce carbon dioxide (CO2) emissions. However, to date, laboratory experiments have mainly been conducted to simulate NCG coinjection with steam in the early stage of SAGD. There has been limited research on the NCG coinjection into the mature SAGD steam chamber. For this study, five sets of 2D physical simulation experiments are introduced and designed based on NCG coinjection with steam into the sand-packed model. The influencing factors of steam-assisted and gas push (SAGP) are analyzed through experiments, including different NCGs [methane (CH4), CO2, and nitrogen (N2)] and coinjection of NCG at different times (i.e., during the lateral expansion and descending stages of the steam chamber). The results indicate that the mechanism of SAGP includes reducing the steam consumption, maintaining the pressure balance of the steam chamber, reducing the partial pressure of the steam, maintaining the quality of the steam, and improving the displacement efficiency of the steam during the lateral expansion of the steam chamber. In addition, the top gravity displacement is the primary mechanism during the later stage of pure gas injection, which manifests that the residual oil at the bottom of the steam chamber is further recovered by using the residual heat of the the steam chamber. Compared with SAGD, the recovery of CO2-assisted SAGD (CA-SAGD), CH4-assisted SAGD (MA-SAGD), and N2-assisted SAGD (NA-SAGD) increased 6.8%, 5.4%, and 4.4%, respectively. The NCG coinjection effect was better during the descending stage of steam chamber, and the oil recovery was 4.7% higher than that during the lateral expansion stage. The selection of NCG and coinjection timing plays a crucial role in improving the ultimate oil recovery and OSR during the middle and later stages of SAGD in superheavy oil reservoirs.

Setting the stage for plant–soil feedback: Mycorrhizal influences over conspecific recruitment, plant and fungal communities, and coevolution

Abstract Plant–soil feedback (PSF) plays a central role in determining plant community dynamics, yet our understanding of how different combinations of plants and microbes influence PSF remains limited. Plants of different mycorrhizal types often exhibit contrasting PSF outcomes, influencing plant recruitment and spatial structure. Generalizing across plant species based on mycorrhizal type creates the potential to examine broader effects on ecological communities. We review mechanisms contributing to different PSF outcomes between arbuscular mycorrhizal and ectomycorrhizal trees. We focus on how plant and fungal traits that differ between mycorrhizal types interact with pathogenic and saprotrophic microorganisms and nutrient and carbon cycling. Synthesis. Building on this framework, we propose several new research directions. First, mycorrhizal‐induced changes in soils can operate beyond the conspecific level, spilling over from abundant plant species onto less abundant ones. This community‐level ‘mycorrhizal spillover’ is hypothesized to affect PSF in ways that are additive and interactive with conspecific density dependence. Second, we describe how mycorrhizal effects on PSF could structure the way plant communities respond to global change. Third, we discuss how they may influence plant evolution by altering the balance of selection pressures on traits and genes related to pathogen defence and mutualism formation.

A Highly Sensitive 3D-Printed Flexible Sensor for Sensing Small Pressures in Deep-Sea High-Pressure Environment.

The origin of life on Earth is believed to be from the ocean, which offers abundant resources in its depths. However, deep-sea operations are limited due to the lack of underwater robots and rigid grippers with sensitive force sensors. Therefore, it is crucial for deep-sea pressure sensors to be integrated with mechanical hands for manipulation. Here, a flexible stress sensor is presented that can function effectively under high water pressure in the deep ocean. Inspired by biological structures found in the abyssal zone, our sensor is designed with an internal and external pressure balance structure (hollow interlocking spherical structure). The digital light processing (DLP) three-dimensional (3D) printing technology is utilized to construct this complex structure after obtaining optimized structural parameters using finite element simulation. The sensor exhibits linear sensitivity of 0.114 kPa-1 within the range of 0-15 kPa and has an extremely short response time of 32 ms, good dynamic-static load response capability, and excellent resistance cycling stability. It shows high sensitivity of 1.74 kPa-1 even under 30 MPa static water pressures and the theoretical working pressure can exceed 110 MPa, which provides a new solution for deep-sea robots.

Modeling and analysis of polypropylene copolymer properties and pressure stability for integrated tubular loop reactor and MZCR

In the context of the emerging multizone circulating reactor (MZCR) operating with gas–solid phases, maintaining pressure balance is crucial for both reactor stability and achieving intended product quality. In this study, the method of moments, reactor model and pressure balance model are coupled to model and analyze an entire process flow for propylene (co)polymerization, which integrates a pre-polymerization tubular loop reactor (TLR) with a main polymerization MZCR. The modeling results unveil the relevance of pre-polymerization in the entire MZC process flow. Additionally, the influence of typical operating parameters on both the pressure stability and copolymer properties is investigated. To further visually identify the pressure-stable boundary of the MZCR, a method based on analyzing the pressure balance loop is proposed. The current study has illustrated the variation trends of pressure drops and product properties under typical operating conditions, identifying an operational range essential for reactor safety.

Large-deformation finite-element modelling of face instability during tunnelling in clayey soils: Incorporating dynamic excavation process

Earth pressure balance (EPB) shield tunnelling plays a crucial role in urban infrastructure development but faces challenges due to potential face instability. Previous studies often overlook the impact of dynamic excavation processes on face stability, particularly in clayey soils. This study proposes a three-dimensional coupled Eulerian-Lagrangian (CEL) large-deformation approach to explore the failure process of tunnel face in clayey soils during both EPB shutdown and excavation conditions by incorporating the influence of dynamic excavation process. The findings reveal that the face stability during dynamic excavation conditions is consistently lower than that during EPB shutdown, indicating that neglecting dynamic excavation effects could overestimate face stability, potentially compromising construction safety. Moreover, when considering the dynamic excavation process, the opening ratio ξ (the ratio between the cross-section area of cutterhead opening to the total area of tunnel face) is a critical factor affecting face stability. As expected, the face is more stable for a small opening ratio (e.g., ξ = 15 %) while face stability is reduced for a large opening ratio (e.g., ξ = 30 % and 50 %). This is because for large opening ratio, the soil disturbance caused by the cutterhead excavation process exceeds the supportive effect that the cutterhead panels can provide to the face. Finally, the obtained numerical results were used to calculate support pressure in a real tunnel project considering the dynamic excavation process, which matches well with the measured data in the project, validating the effectiveness and superiority of the current CEL approach in modelling face instability and estimating face support pressure. This study offers a significant advancement over the traditional methods for the design of support pressure in clayey soils, providing new insight into the dynamic cutterhead-soil interaction and valuable guidance for reducing the risk of face collapse.

Assessment of plasticity of muddy soil for earth pressure balance shield tunneling

This research delves into managing the plasticity of muddy soil in earth pressure balance (EPB) shield tunneling, crucial for ensuring tunnel stability and efficient sediment management in urban construction. The study utilizes a combination of a small-scale model experiment and a computer-aided engineering (CAE) analysis through the moving particle simulation (MPS) method to investigate how the plasticity of muddy soil, adjusted by mixing excavated soil with a bentonite solution, impacts the earth pressure within a tunneling chamber. The experimental setup meticulously simulates the tunneling process, measuring the variations in earth pressure that occur in response to the different states of plasticity induced by the agitation of the muddy soil. The findings reveal that earth pressure is a reliable indicator of the soil’s plasticity, significantly correlating with the slump value and vane shear strength, thus affecting tunnel stability and the operation of machinery. The CAE analysis, underpinned by MPS, accurately mirrors the experimental outcomes, endorsing its use for assessing and visualizing the plasticity and fluidity of muddy soil in tunneling scenarios. The results of this study demonstrate that MPS-CAE analysis is an effective tool for improving sediment management strategies and optimizing EPB shield tunneling operations, highlighting the critical role of soil plasticity in ensuring tunnel face stability and project success. This research reveals that earth pressure measured by the agitation blade can serve as a reliable indicator of the plasticity of muddy soil in the chamber. This enables real-time and on-site evaluation of soil conditions during EPB shield tunneling.

Acetylcholinesterase Inhibitor Ameliorates Early Cardiometabolic Disorders in Fructose-Overloaded Rat Offspring.

We investigate the role of galantamine on autonomic dysfunction associated with early cardiometabolic dysfunction in the offspring of fructose-overloaded rats. Wistar rats received fructose diluted in drinking water (10%) or water for 60 days prior to mating. Fructose overload was maintained until the end of lactation. The offspring (21 days after birth) of control and fructose-overloaded animals were divided into three groups: control (C), fructose (F) and fructose + galantamine (GAL). GAL (5 mg/kg) was administered orally until the offspring were 51 days old. Metabolic, hemodynamic and cardiovascular autonomic modulation were evaluated. The F group showed decreased insulin tolerance (KITT) compared to the C and GAL groups. The F group, in comparison to the C group, had increased arterial blood pressure, heart rate and sympathovagal balance (LF/HF ratio) and a low-frequency band of systolic arterial pressure (LF-SAP). The GAL group, in comparison to the F group, showed increased vagally mediated RMSSD index, a high-frequency band (HF-PI) and decreased LF/HF ratio and variance in SAP (VAR-SAP) and LF-SAP. Correlations were found between HF-PI and KITT (r = 0.60), heart rate (r = -0.65) and MAP (r = -0.71). GAL treatment significantly improved cardiovascular autonomic modulation, which was associated with the amelioration of cardiometabolic dysfunction in offspring of parents exposed to chronic fructose consumption.

Characteristics and modification mechanism of recycled waste silty clay slurry as the shield slag conditioner

The construction process of earth pressure balance shield (EPBS) generates a large amount of shield slag. In China, the conventional methods for treating shield slag involve crude landfill and stockpiling, resulting in increased cost and significant environmental issues. To expand the recycling of shield slag, this study proposes to use waste silty clay to completely replace bentonite as a conditioner in coarse-grained strata. Firstly, the physical properties of silty clay slurries are investigated with four additives. There are six modified silty clay slurries with good improved performance. Then, analyzing the rheological properties of six modified silty clay slurries, and verifying the feasibility of replacing bentonite slurry with modified silty clay slurry. Next, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Zeta potential were used to analyse the micromechanisms, molecular structures and molecular forces of 14 % bentonite slurry, silty clay slurry with a soil-water ratio of 1:1, sodium carbonate 3 % and sodium silicate 0.1 % in a silty clay slurry with a soil-water ratio of 1:1. Finally, the slump test was carried out to verify the improvement effect of the modified silty clay slurry on the shield slag. The results show that sodium carbonate modified silty clay slurry has a higher interlayer water content and greater ion exchange capacity. When the soil-water ratio is 1:1 and the concentration of sodium carbonate is 3 %, the apparent viscosity and shear force of the modified silty clay slurries are between those of bentonite slurries with a concentration of 10 % and 14 %. Additionally, the modified silty clay slurry showed a stable microstructure and good residue amendment effect, making it suitable as a soil conditioner during EPBS construction in coarse-grained strata. This study offers a viable approach for recycling EPBS slurry.

Advances in the structural basis for angiotensin-1 converting enzyme (ACE) inhibitors.

Human somatic angiotensin-converting enzyme (ACE) is a key zinc metallopeptidase that plays a pivotal role in the renin-angiotensin-aldosterone system (RAAS) by regulating blood pressure and electrolyte balance. Inhibition of ACE is a cornerstone in the management of hypertension, cardiovascular diseases, and renal disorders. Recent advances in structural biology techniques have provided invaluable insights into the molecular mechanisms underlying ACE inhibition, facilitating the design and development of more effective therapeutic agents. This review focuses on the latest advancements in elucidating the structural basis for ACE inhibition. High-resolution crystallographic studies of minimally glycosylated individual domains of ACE have revealed intricate molecular details of the ACE catalytic N- and C-domains, and their detailed interactions with clinically relevant and newly designed domain-specific inhibitors. In addition, the recently elucidated structure of the glycosylated form of full-length ACE by cryo-electron microscopy (cryo-EM) has shed light on the mechanism of ACE dimerization and revealed continuous conformational changes which occur prior to ligand binding. In addition to these experimental techniques, computational approaches have also played a pivotal role in elucidating the structural basis for ACE inhibition. Molecular dynamics simulations and computational docking studies have provided atomic details of inhibitor binding kinetics and energetics, facilitating the rational design of novel ACE inhibitors with improved potency and selectivity. Furthermore, computational analysis of the motions observed by cryo-EM allowed the identification of allosteric binding sites on ACE. This affords new opportunities for the development of next-generation allosteric inhibitors with enhanced pharmacological properties. Overall, the insights highlighted in this review could enable the rational design of novel ACE inhibitors with improved efficacy and safety profiles, ultimately leading to better therapeutic outcomes for patients with hypertension and cardiovascular diseases.

Preparation of eggshell-based materials and their adsorption performance on Fe(III) in water*

Abstract If there is too much trivalent iron in the body, it will disrupt the balance of osmotic pressure inside the body, and its heavy metal properties will denature proteins. Therefore, effective management of industrial pollution source wastewater is very important for environmental protection and human’s health. Calcium carbonate particles have a good ability to adsorb trivalent iron in wastewater. The aim is to prepare porous calcium carbonate by a template method using eggshell powder, hydrochloric acid, sodium stearate, and anhydrous sodium carbonate solution as the raw materials and research the adsorption properties of porous calcium carbonate to trivalent iron. Porous calcium carbonate was prepared by a template method using eggshell powder, hydrochloric acid, sodium stearate, and anhydrous sodium carbonate solution as the raw materials. The morphology and adsorptive properties of Fe (III) of the porous calcium carbonate were analyzed by scanning electron microscope (SEM) and UV-visible spectrophotometer (UV). The best value was found between different temperatures, time, and pH. The results verified that the maximum amount of adsorption was obtained when calcination was 400°C, pH was 5, time was 60 min, and the input amount was 20 mg. The adsorption of porous calcium carbonate to Fe (III) is chemical and has a better adsorption effect.

Intelligent optimization prediction of screw conveyor speed for earth pressure balance shield machine based on complete ensemble empirical mode decomposition of adaptive noise and deep learning

The excavation stratum of the earth pressure balance (EPB) shield machine is complex and changeable. For ensuring the excavated interface stabilization, the rotational speed of screw conveyor must be precisely controlled to maintain the balance of earth pressure in sealed cabin and to avoid accidents such as ground collapse or upliftment. A data-driven intelligent optimal model is presented by the paper, which organically integrates the complete ensemble empirical mode decomposition of adaptive noise (CEEMDAN), sparrow search algorithm (SSA) and long short-term memory (LSTM) network to achieve accurate prediction of screw conveyor rotation speed. Firstly, Pearson correlation analysis method is used to analyze the historical data of shield tunneling, and the tunneling parameters strongly related to the change of screw conveyor rotation speed are obtained as model input. Secondly, the CEEMDAN is used to decompose the obtained parameter data set into several modal components, and then the denoised data is reorganized to capture the changing characteristics of the original data and reduce the complexity of the data. Then, the parameters such as the learning rate of the LSTM network are optimized by using the strong global search ability of SSA to enhance the prediction precision further in the model. Finally, based on decomposed and reorganized data, SSA-LSTM is used to establish a rotation speed intelligent prediction model realize precise controlling of screw conveyor rotation speed. The simulation experiment is carried out by using the construction data of a section of Beijing Metro Line 10, and the results of three evaluation indexes of the model are given: Mean Absolute Error (MAE) is 0.02878, Mean Absolute Percentage Error (MAPE) is 0.00882 and R2 is 0.99909, which shows that the model has good prediction performance. The control effect of the method on the earth pressure balance of the sealed cabin is tested, and the maximum error value is 0.25%, which verifies the engineering applicability of the method.

Hydraulic fracture characterization of debris-rich ice hole for polar geological drilling based on Peridynamics

Polar geological drilling is crucial to investigating the earth's environment and climate evolution. Hydraulic fracturing occurs around the ice holes when drilling into the complex debris-rich ice before entering the bedrock. Based on the nonlocal theory, the ice-debris structure is considered in the stability of the borehole wall, and a peridynamics model is developed to explore fracture initiation and propagation characteristics around the debris-rich ice hole. The integrated equation describes the mechanical behavior of ice holes, and the continuous and discontinuous spaces are described uniformly around debris-rich ice holes, avoiding the singularity of local continuum mechanics at the interface and crack tip. In this paper, the separation behavior of the interface is simulated between ice and debris. The cracking propagation process, the influence of debris size and shape, and horizontal pressure are analyzed. The results show that at a hydraulic pressure of 4.0 MPa, 8 radial cracks are initiated from the wall of the ice hole containing circular and elliptical debris, with the final crack volume of 0.66% and 1.40%, respectively. The cracks near the hole wall propagate a circumferential direction after turning or branching, leading to peeling in the ice hole containing elliptical debris with inclination angles of 30° and 60°. Hydraulic pressure balances stress distribution around debris-rich holes when horizontal pressure ranges from 1.2 to 2.4 MPa. When drilling into debris-rich ice formations at different debris and horizontal pressures, it is imperative to adjust promptly the density of drilling fluid. This adjustment aims to regulate the hydraulic pressure within the hole, minimize crack distribution, and ensure safe access to bedrock for coring.

Mechanism of slag discharge failures in earth pressure balance shield screw conveyor: A theoretical model-based investigation

The screw conveyor gushing may cause a sudden drop in pressure in the earth chamber, leading to excessive settlement of the surface and nearby buildings or structures, and even catastrophic accidents such as tunnel collapse. This paper presents a comprehensive investigation into slagging failures associated with earth pressure balance shield screw conveyors, categorizing them into rheological failure and permeability failure. Further, a permeability failure theoretical model and a Bingham fluid-based rheological failure model are developed. The above models can describe the conditions and mechanism of screw conveyor spurt taking into account shield parameters, formation characteristics, chamber pressure, and conditioned soil properties. In addition, a sensitivity analysis is conducted on the critical permeability coefficient and critical shear strength of the discharged soil, with a focus on a specific case project. The results underscore the significant impact of the screw conveyor pitch, water head at the entrance, and chamber pressure on the critical permeability coefficient and shear strength. Building on these findings, this paper proposes an anti-surge control index and strategy for shield screw conveyors, taking into account the ratio of shield covering soil thickness to shield diameter. It is recommended that when the shield soil covering layer thickness exceeds twice the shield diameter, real-time modification of the soil parameters, based on the shield tunneling depth, especially the shear strength, is essential for anti-surge control. This study provides engineers with valuable insights into conditioned soil and implements effective surge management strategies for screw conveyors.

Multiline observations of hydrogen, helium, and carbon radio-recombination lines toward Orion A: A detailed dynamical study and direct determination of physical conditions

We present a study of hydrogen, helium, and carbon millimeter-wave radio-recombination lines (RRLs) toward 10 representative positions throughout the Orion Nebula complex, using the Yebes 40 m telescope in the Q band (31.3 GHz to 50.6 GHz) at an angular resolution of about 45″ (~0.09 pc). The observed positions include the Orion Nebula (M42) with the Orion Molecular Core 1, M43, and the Orion Molecular Core 3 bordering on NGC 1973, 1975, and 1977. While hydrogen and helium RRLs arise in the ionized gas surrounding the massive stars in the Orion Nebula complex, carbon RRLs stem from the neutral gas of the adjacent photo-dissociation regions (PDRs). The high velocity resolution (0.3 km s−1) enables us to discern the detailed dynamics of the RRL emitting neutral and ionized gas. We compare the carbon RRLs with SOFIA/upGREAT observations of the [C II] 158 µm line and IRAM 30 m observations of the 13CO (J = 2−1) line (the complete map is presented here for the first time). We observe small differences in peak velocities between the different tracers, which cannot always be attributed to geometry but potentially to shear motions. Using the far-infrared [C II] and [13C II] intensities with the carbon RRL intensities, we can infer physical conditions (electron temperature Te and electron density ne, converted to hydrogen nuclei density nH by dividing by the carbon gas-phase abundance 𝒜c ≃ 1.4 × 10−4) in the PDR gas using nonlocal thermal equilibrium excitation models. For positions in OMC1, we infer ne ≃ 20–40 cm−3 and Te ≃ 210–240 K. On the border between OMC1 and M43, we observe two gas components with ne ≃ 2 cm−3 and ne ≃ 8 cm−3, and Te ≃ 100 K and Te ≃ 150 K. In M43, we infer ne ≃ 2–3 cm−3 and Te ≃ 140 K. The Extended Orion Nebula southeast of OMC1 is characterized by ne ≃ 2 cm−3 and Te ≃ 180 K, while OMC3 has ne ≃ 1 cm−3 and Te ≃ 130 K. Our observations are sensitive enough to detect faint lines toward two positions in OMC1, in the BN/KL PDR and the PDR close to the Trapezium stars, that may be attributed to RRLs of C+ or O+. In general, the RRL line widths of both the ionized and neutral gas, as well as the [C II] and 13CO line widths, are broader than thermal, indicating significant turbulence in the interstellar medium, which transitions from super-Alfvénic and subsonic in the ionized gas to sub-Alfvénic and supersonic in the molecular gas. At the scales probed by our observations, the turbulent pressure dominates the pressure balance in the neutral and molecular gas, while in the ionized gas the turbulent pressure is much smaller than the thermal pressure.

Geological adaptive intelligent control of earth pressure balance shield machine based on deep reinforcement learning

Scientific and precise control of tunnelling parameters is of utmost importance during the construction of shield machines. Given the complexity of the working environment, manual operation is highly prone to causing safety accidents. Therefore, achieving intelligent control of the shield machine is crucial. Based on this, this paper proposes a geological adaptive intelligent control method of earth pressure balance shield machine using the Deep Deterministic Policy Gradient (DDPG) algorithm as the framework, with Actor-Critic as the basis. Firstly, DDPG agent is constructed to replace the screw conveyor control system as the main body of strategy implementation. Secondly, an environmental model is established by utilizing the mechanism model between the sealed cabin pressure and the screw conveyor speed. The real-time sealed cabin pressure, target pressure, and pressure error serve as the state space, while the screw conveyor speed is used as the action space. A combined reward function is set based on safety and accuracy. Finally, the Actor network interacts with the environment under the supervision of the reward function and Critic network. Successful training is achieved when the cumulative reward value is maximized, resulting in the output of optimal control strategy. In this paper, the method dynamically regulates the screw conveyor speed by interacting with the geological environment, to realize the precise control of the sealed cabin pressure and ensure the dynamic balance between sealed cabin pressure and excavation face pressure. The test results show that this method has a good control effect on the sealed cabin pressure under various geological conditions, and can complete 72 kinds of soil transition tasks. It has strong soil adaptability and can respond well to the dynamic changes of soil conditions. This approach enhances the intelligence of the shield machine, mitigating inaccuracies attributed to human operation, which provides a guarantee of safe shield machine operation, whilst exhibiting valuable engineering applications.

Experimental study on granule trajectory tracking for the EPB shield tunneling in sandy cobble stratum

An investigation into the movement characteristics of granules during Earth Pressure Balance (EPB) shield tunneling contributes significantly to understanding the interaction between the shield machine and the soil. This understanding also enables researchers to gain deeper insights into the cutting and guiding effects of the shield cutterhead on the soil, thus providing a scientific basis for optimizing shield tunneling parameters and cutterhead designs. To achieve this, indoor model shield tunneling experiments were conducted using independently developed shield tunneling equipment and spatial positioning devices developed by our research group. The research investigated the spatial movement trajectories, radial diffusion, and axial movement characteristics of granules at the face subjected to the action of a spoke-type cutterhead. Furthermore, the study proposes the use of average diffusion degree and movement rates of granules as metrics for evaluating the cutting and steering performance of the cutterhead. The influence of cutterhead rotational speed and advance rate on the movement characteristics of granules was further explored based on these two indicators. The study’s findings reveal the following: (1) Granules at the face predominantly exhibit a spiral movement trajectory when the EPB shield tunneling machine operates in a dynamic equilibrium state. (2) The cutting and steering performance of the cutterhead’s various areas is enhanced progressively from the center to the outer edge, as evidenced by a gradual decrease in the average diffusion degree of granules and an increase in the average axial movement rate (AMR). (3) The AMR and average diffusion degree of granules are influenced by both the rotational speed of the cutterhead and the advance rate of the shield machine. Optimal matching of the rotational speed and advance rate maximizes the average AMR of granules, minimizes the average diffusion degree, reduces the torque on the cutterhead to its lowest point, and consequently, optimizes the efficiency of shield tunneling. This research presents a novel perspective and methodology for understanding the movement characteristics of granules during shield tunneling operations. The outcomes of this study provide valuable insights for the structural design of shield machine cutterheads and the optimization of tunneling parameters.