True Conditions Research Articles

Dynamic Strain Rate Effect and Macro–Micro-Fracture Mechanism of Raw Coal Under True Triaxial Conditions

Dynamic Strain Rate Effect and Macro–Micro-Fracture Mechanism of Raw Coal Under True Triaxial Conditions

Understanding and mitigating settlement in gypseous soils: A comprehensive study on the role of saturation and soil stabilization techniques

This study examines the influence of saturation levels and soil additives on the load-settlement properties of gypseous soils, a significant geotechnical concern in regions like Iraq. The study analyzes the deficiencies of conventional oedometer testing, which often fail to adequately represent the true unsaturated conditions prevalent in these soils. The research investigates the impact of varying matric suction (Ψ) values on the compressibility of untreated, cement-treated, and CKD-treated gypseous soils. A modified oedometer apparatus, engineered to control and quantify matric suction, was used to replicate diverse moisture conditions. The experimental program investigated soils with varying gypsum contents (8.8%, 12.66%, and 30%), reflecting the diversity of gypseous soils seen in the field. The findings demonstrate that increased saturation levels significantly enhance settling in gypseous soils. As matric suction increases, settlement is markedly reduced due to elevated soil suction pressure and enhanced effective stress. The findings underscore the importance of unsaturated conditions in improving the load-bearing capacity of these soils. The study illustrates the advantageous impacts of cement and CKD treatments in reducing settling. The effectiveness of these methods is particularly apparent in partially saturated environments, emphasizing the need of including matric suction into design considerations. This research improves understanding of the complex behavior of unsaturated gypseous soils. The findings have practical importance for geotechnical engineering, including foundation design, ground improvement methods, and the development of effective solutions for settlement issues in areas with high gypsum concentrations.

The Ripple Effects of Financial Fraud: Investor Trust and Risk Appetite Post-Kangmei Pharmaceutical

The financial fraud at Kangmei Pharmaceutical (stock code: 600518) has had profound implications for retail investors. This paper, through data analysis, explores the correlation between information asymmetry and investment outcomes for retail investors. Information asymmetry often leaves retail investors unable to access the true financial state and operational conditions of companies, leading them to make speculative investments. Post-exposure, as information transparency increased, retail investors became aware of the company's financial issues and rushed to sell, causing a stock plunge. This highlights how information asymmetry not only affects investment decisions but also amplifies market volatility. To mitigate risks from information asymmetry, regulators must strengthen oversight and penalties, improve disclosure transparency and authenticity, while investors need to enhance self-protection awareness and information gathering and analysis capabilities. Only then can we minimize the impact of information asymmetry on retail investors and uphold fairness and stability in financial markets. This paper suggests that by implementing a robust regulatory framework and encouraging proactive investor education, we can better safeguard retail investors from the detrimental effects of information asymmetry, thereby fostering a more resilient and equitable financial market ecosystem.

Detecting soil mixing, grain size distribution, and clogging potential of tunnel excavation face by classification-regression algorithms using EPBM operational data

Earth pressure balance machine (EPBM) operation is sensitive to the properties of the excavated soil due to the requirements of proper soil conditioning and maintenance of necessary chamber pressure. However, soil properties are invariably only available at a limited number of borehole explorations and soil samplings conducted during the subsoil investigation. Thus, it is crucial to identify properties of the tunnel excavation face, such as clay-sand mixed conditions, grain size distributions, and clogging potential along the whole alignment beside the few borehole locations to attain optimally efficient EPBM operation. Therefore, this paper presents the development of machine learning prediction models (i.e., classifiers and regressors) to estimate the properties of the tunnel excavation face using EPBM operational data collected during the tunneling operation as input features. Geotechnical data collected from boreholes and soil samples can be used to validate prediction models and calibrate them. To develop such models, the Northgate Link Extension (N125) tunneling project, constructed in Seattle, Washington, the USA, is used to capture and identify the true ground conditions. The results indicate successful prediction performances by the models, providing indication that EPBM parameters are crucial pointers of the tunnel excavation face properties to help attain optimally efficient EPBM operation.

Interaction behavior between hydraulic fractures and interface in coal-rock complex rock layer: Experimental study and application exploration

To achieve long-term and efficient gas extraction in soft, low-permeability coal seams, this study conducted hydraulic fracturing experiments on coal-rock complexes under true triaxial conditions. The pattern of hydraulic fractures (HFs) was reconstructed based on the fractal dimension concept. The results indicate that the tendency of the complex rock layers to initiate fractures toward the coal weakens the trend of increasing fracture initiation pressure with rising geostress. When HFs interact with the interface, the extension pressure significantly decreases. With the lateral pressure coefficient decreasing, HFs tend to extend toward the coal and be captured by the interface, transitioning from a single-wing to a double-wing shape and approaching a symmetrical conjugate state. Only when the vertical principal stress is sufficiently large can HFs separate from the interface. Based on the derived distribution function of induced stress in the coal-rock matrix around the HFs, the displacement conditions of the coal, rock, and interface were examined. The interaction process of rock layer HFs and the interface was divided into three stages: deflection, capture, and separation. The applicability of this study to high-gas soft coal seams was discussed, and a gas management plan involving roof fracturing and full-period extraction was proposed, with the aim of providing a theoretical foundation for the co-extraction and efficient utilization of coal and gas in mines.

Calculation method and evolution rule of the strain energy density of sandstone under true triaxial compression

Deep rock masses are typically in complex stress states, and research on the evolution of their strain energy density is of highly important for understanding their failure characteristics. In this work, a true triaxial stress‒balanced unloading test is designed to analyze the ud and ue evolution of sandstone under true triaxial compression conditions. The study results indicate that as σ1 increases, the elastic strain decreases in the σ2 and σ3 directions, whereas the residual strain progressively increases, and the magnitude of decrease in elastic strain exceeds the magnitude of increase in residual strain. Throughout the loading process of σ1, ue progressively decreases in the σ2 and σ3 directions, whereas ud gradually increases, and the magnitude of decrease in ue surpasses the magnitude of increase in ud. The ud and ue of sandstone under different stress levels were calculated via true triaxial stress‒balanced unloading tests, and the evolution of ud and ue in the three principal stress directions and the overall strain energy density of sandstone followed a linear energy storage law. On the basis of this law and the true triaxial stress‒balanced unloading test, a new method for calculating the true triaxial ud and ue was proposed. A study on the σ1 unloading stress path revealed that the σ1 unloading stress path significantly affects the storage and dissipation of the strain energy density in the three principal stress directions of sandstone. On the basis of the research results, the criteria for determining rockbursts were discussed.

Innovative server simulator for data centers and critical indices of performance evaluation

Server simulators, also known as dummy loads, are used to simulate real IT equipment for performance examining of data centers. Without these tests, potential failures could result in significant losses. Due to oversimplified designs and lack of evaluation methods, commercial dummy loads often fail to reflect accurately the true conditions of the real servers in data centers. In this study, a novel dummy-chip server simulator (DCSS) is developed, which can well reproduce the working mechanism of real servers. In this paper, three indices are proposed for the first time to evaluate the performance from different perspectives, i.e. Coefficient of Heat Removal (CHR) for heat removal capability, Coefficient of Temperature Deviation (α) for temperature rating, and Power Usage per Computing (PUC) for energy and computation efficiency. Experimental tests are conducted in this study, and results show that the good performance of the DCSS approaching the real server, and the values of CHR, α, and PUC indicate significant improvements compared to the commercial dummy load. The findings of this study present straightforward guidance for IT server simulator design, and demonstrate the advancement of DCSS and proposed index for data center performance evaluation.

Analysis of failure properties of red sandstone with structural plane subjected to true triaxial stress paths

In order to study the mechanical behavior and failure characteristics of rock mass with the structural plane in complex deep stress environment, the QKX-YB200 true triaxial rockburst test system, acoustic emission, and digital video recorder were adopted to conduct true triaxial loading and unloading indoor tests on the red sandstone cube specimens. The results show that: (1) Under true triaxial loading conditions, all specimens propagate in the form of anti-wing crack, and the dip angle of the structural plane is linearly related to the average value of the anti-wing crack propagation angle; under true triaxial unloading conditions, the specimens with structural plane dip angles of 30°, 45°, and 60° propagate in the form of wing crack, while those with a 90° angle propagate anti-wing cracks, and the closure of structural plane is related to the the crack type at the tips of structural plane. (2) The unstable failure stages in the stress–strain curve under true triaxial unloading are longer and exhibit more pronounced fluctuations; the peak strength of the specimens under the conditions of true triaxial loading and unloading decrease first and then increase with the increase of the dip angle, reaching the lowest at 45°. (3) During the true triaxial unloading tests, the rockburst degree of the intact rock specimens is more violent than that of the specimens with a structural plane. Additionally, the dip angle of the structural plane influences the severity of rockbursts under the same stress path. (4) The crack propagation mechanism and the closure degree of structural planes under different true triaxial stress paths and dip angles are discussed. It is observed that the crack initiation mode around the structural plane tips and the crack mode near free surface are closely related to the stress environment in different areas of the specimens. (5) Based on the indoor test results and previous experimental data, the differences in peak strength characteristics between open structural planes and closed structural planes are preliminarily analyzed and compared.

Measurement bias in self-heating x-ray free electron laser experiments from diffraction studies of phase transformation in titanium

X-ray self-heating is a common by-product of X-ray Free Electron Laser (XFEL) techniques that can affect targets, optics, and other irradiated materials. Diagnosis of heating and induced changes in samples may be performed using the x-ray beam itself as a probe. However, the relationship between conditions created by and inferred from x-ray irradiation is unclear and may be highly dependent on the material system under consideration. Here, we report on a simple case study of a titanium foil irradiated, heated, and probed by a MHz XFEL pulse train at 18.1 keV delivered by the European XFEL using measured x-ray diffraction to determine temperature and finite element analysis to interpret the experimental data. We find a complex relationship between apparent temperatures and sample temperature distributions that must be accounted for to adequately interpret the data, including beam averaging effects, multivalued temperatures due to sample phase transitions, and jumps and gaps in the observable temperature near phase transformations. The results have implications for studies employing x-ray probing of systems with large temperature gradients, particularly where these gradients are produced by the beam itself. Finally, this study shows the potential complexity of studying nonlinear sample behavior, such as phase transformations, where biasing effects of temperature gradients can become paramount, precluding clear observation of true transformation conditions.

Nonlinear dynamics of the semi-infinite ferromagnetic samples with an easy-plane anisotropy

The modification of the inverse scattering problem is proposed to investigate solitons and dispersive waves in the framework of the Landau–Lifshitz model for semi-infinite ferromagnet with an ¡¡easy-plane¿¿ anisotropy under the mixed boundary conditions, corresponding to different degrees of spin pinning on the edge of the sample. New types of solitons are obtained and their elastic reflection from the edge of the sample is analyzed. Spectral expansions of the integrals of motion for solitons and waves are found. Additional integrals of motion are established that guarantee true boundary conditions for solitons, when they interact with the edge of the sample.

Beyond MABEL: An Integrative Approach to First in Human Dose Selection of Immunomodulators by the Health and Environmental Sciences Institute (HESI) Immuno-Safety Technical Committee (ITC).

Administration of a new drug candidate in a first-in-human (FIH) clinical trial is a particularly challenging phase in drug development and is especially true for immunomodulators, which are a diverse and complex class of drugs with a broad range of mechanisms of action and associated safety risks. Risk is generally greater for immunostimulators, in which safety concerns are associated with acute toxicity, compared to immunosuppressors, where the risks are related to chronic effects. Current methodologies for FIH dose selection for immunostimulators are focused primarily on identifying the minimum anticipated biological effect level (MABEL), which has often resulted in sub-therapeutic doses, leading to long and costly escalation phases. The Health and Environmental Sciences Institute (HESI) - Immuno-Safety Technical Committee (ITC) organized a project to address this issue through two complementary approaches: (i) an industry survey on FIH dose selection strategies and (ii) detailed case studies for immunomodulators in oncology and non-oncology indications. Key messages from the industry survey responses highlighted a preference toward more dynamic PK/PD approaches as in vitro assays are seemingly not representative of true physiological conditions for immunomodulators. These principles are highlighted in case studies. To address the above themes, we have proposed a revised decision tree, which expands on the guidance by the IQ MABEL Working Group (Leach et al. 2021). This approach facilitates a more refined recommendation of FIH dose selection for immunomodulators, allowing for a nuanced consideration of their mechanisms of action (MOAs) and the associated risk-to-benefit ratio, among other factors.

Mechanical properties and constitutive model of artificial frozen sandy soils under true triaxial stress state conditions

Triaxial compression tests were conducted on frozen sandy soils under a constant minimum principal stress (σ3 = 1.6 MPa) and various intermediate principal stresses (σ2 = 1.6, 3.4, 5.2, 7.0, 8.8, 9.8 MPa). The purpose of the research was to investigate the influence of intermediate principal stress on mechanical properties of frozen soil, and to establish a constitutive model to predict the stress-strain relationship of frozen soil under complex stress state. The test results obtained demonstrated that the crack damage stress and failure stress initially increase and then decrease with an increase in the intermediate principal stress. However, the crack initiation stress exhibits an initial increase up to a specific value, after which it stabilizes. From the perspective of crack propagation, the influence mechanism of intermediate principal stress on the strength was discussed. With the variation of stress state, the difference between intermediate principal strain and minimum principal strain gradually increases. The deformation difference was revealed using the stress superposition principle and Poisson's effect. Finally, the constitutive model based on the Weibull distribution and Drucker-Prager strength criterion can accurately represent the stress-strain relationships of frozen sandy soils under true triaxial stress states.

Processing of Counterfactual Conditional Sentences with Differential Propositional Truth-Value in Mandarin Chinese: Evidence from ERP

Although many studies document the role of propositional truth-value in human psychological reading behavior, there is a relative paucity of research examining the role of differential propositional truth-value in processing Chinese counterfactual conditionals. This study is to investigate the role of differential propositional value in processing Chinese counterfactual conditionals by means of ERPs (event-related potentials). The study is based on comprehending two types of Chinese counterfactual conditionals, which is propositional truth value introduced by two different markers of conditional conjunctions in the protasis and apodosis, such as true counterfactual conditional markers jiaru (if) & jiu (so) in the sentence wo xiang yu jiaru you tui jiu keyi zai shuixia zhixi (I think if fish had legs so they could stifle under water), and false counterfactual conditional markers ruguo (if) & namo (then) in the sentence wo xiang gou ruguo you lin namo keyi zai shuixia huxi (I think if dogs had scales, then they could breathe under water). Two counterfactual propositional values (i.e. true and false propositional values) are constructed through manipulating sentence counterfactuality between the true and false counterfactual conditional markers in the protasis and the apodosis. Twenty-four full-time Chinese college students participated in the ERP study. The results demonstrated that processing the true counterfactual propositional sentences with conditional markers jiaru (if) & jiu (so) elicited the N400 effect relative to false propositional sentences with conditional markers ruguo (if) & namo (then). Moreover, the counterfactual sentences with true propositional conditions varied from the elicitation of the N400 effect in the protasis and absence of the N400 effect in the apodosis, showing that semantic roles may gradually disappear under the impact of truth value of propositional counterfactual condition, and/or the roles of semantic anomaly was eliminated in the accumulated sentence processing. While for the false counterfactual conditional sentences, elicitations of P300 in the protasis and robust N400 effect in the apodosis were shown, indicating the increasing semantic role in the processing. Interestingly, there was the absence of the P600 effect for processing sentences with syntactic violation, suggesting little extra syntactic cost in processing sentences with false propositional condition.

Is Your Training Data Really Ground Truth? A Quality Assessment of Manual Annotation for Individual Tree Crown Delineation

For the accurate and automatic mapping of forest stands based on very-high-resolution satellite imagery and digital orthophotos, precise object detection at the individual tree level is necessary. Currently, supervised deep learning models are primarily applied for this task. To train a reliable model, it is crucial to have an accurate tree crown annotation dataset. The current method of generating these training datasets still relies on manual annotation and labeling. Because of the intricate contours of tree crowns, vegetation density in natural forests and the insufficient ground sampling distance of the imagery, manually generated annotations are error-prone. It is unlikely that the manually delineated tree crowns represent the true conditions on the ground. If these error-prone annotations are used as training data for deep learning models, this may lead to inaccurate mapping results for the models. This study critically validates manual tree crown annotations on two study sites: a forest-like plantation on a cemetery and a natural city forest. The validation is based on tree reference data in the form of an official tree register and tree segments extracted from UAV laser scanning (ULS) data for the quality assessment of a training dataset. The validation results reveal that the manual annotations detect only 37% of the tree crowns in the forest-like plantation area and 10% of the tree crowns in the natural forest correctly. Furthermore, it is frequent for multiple trees to be interpreted in the annotation as a single tree at both study sites.

Experimental and numerical analysis of injection-induced permeability changes in pre-existing fractures

This paper presents a combined laboratory and numerical investigation on the injection-induced permeability changes in pre-existing fractures. The analyses conducted were primarily based on the results of an innovative laboratory experiment designed to replicate the key mechanisms that occur during hydraulic stimulation of naturally fractured rocks and/or faulted zones. The experiment involved pressure-controlled fluid injection into a laboratory-scale pre-existing fracture within a granite block, which was subjected to true triaxial stress conditions. Rough and smooth fractures are investigated, and the results are discussed. Based on the experimental results, two contributing mechanisms were considered to describe the pressure-driven permeability changes in pre-existing fractures: (1) elastic opening/closure leading to a reversible permeability change, and (2) fracture sliding in shear mode, causing dilation and hence an irreversible permeability increase. With these assumptions, an aperture-dependent permeability function was adopted to couple the hydraulic flow with the mechanical deformations along the fracture. Subsequently, a 3D coupled hydro-mechanical model was developed to replicate fluid-injection tests conducted at various conditions, including different stress conditions and fracture surface roughness. The employed modeling framework effectively captured the experimental observations. Our results indicate that the maximum permeability increases twofold.

Biophysical impact of lubricating base oil aerosols on natural pulmonary surfactant film

Lubricating base oils have been extensively employed for producing various industrial and consumer products. Therefore, their environmental and health impacts should be carefully evaluated. Although there have been many reports on pulmonary cytotoxicity and inflammatory responses of inhaled lubricating base oils, their potential influences on pulmonary surfactant (PS) films that play an essential role in maintaining respiratory mechanics and pulmonary immunity remains largely unknown. Here a systematic study on the interactions between an animal-derived natural PS and aerosols of water and representative mineral and vegetable base oils is performed using a novel biophysical assessing technique called constrained drop surfactometry capable of providing in vitro simulations of normal tidal breathing and physiologically relevant temperature and humidity in the lung. It was found that the mineral oil aerosols can impose strong inhibitions to the biophysical property of PS film, while the airborne vegetable oils and water show negligible adverse effects within the studied concentration range. The inhibitory effect is originated from the strong hydrophobicity of mineral oil, which makes it able to disrupt the interfacial molecular ordering of both phospholipid and protein compositions and consequently suppress the formation of condensed phase and multilayer scaffolds in a PS film. Environmental ImplicationUnderstanding the biophysical influence of airborne lubricating base oils on pulmonary surfactant (PS) films can provide new insights into the environmental impacts and health concerns of various industrial lubricant products. Here a comparative study on interactions between an animal-derived natural PS film and the aerosols of water and representative mineral and vegetable base oils under the true physiological conditions was conducted in situ using constrained drop surfactometry. We show that the most frequently used mineral base oil can cause strong inhibitions to the PS film by disrupting the molecular ordering of saturated phospholipids and surfactant-associated proteins at the interface.

Representasi Makna Keikhlasan Pada Series “ Layangan Putus ”

This research was conducted to analyze the representation of sincerity shown by women in the drama series "Layangan Putus." In addition to being a form of mass media that portrays the social life of the community, this series also includes cultural creations that bring important values to the audience, one of which is about marital life rumored with infidelity and how women, especially wives, demonstrate an attitude of sincerity. This study used a qualitative descriptive approach with the analysis of Roland Barthes' semiotics model. The focus of this research was to find the denotative, connotative, and myth meanings in 4 scenes that show the meaning of sincerity. The data collection techniques used were documentation, literature review, and observation. The results of the study show that the meaning of sincerity is demonstrated as an action that refers to social situations, parties harmed in the social structure take action against those who harm them. The attitude of sincerity occurs because of human behaviors that are not in line with their true feelings and conditions and harm others, including family, by surrendering what is considered best in the hope of getting something more deserving in the future. Sincerity is an attitude that women adopt to prove that not all problems need to be responded to and vented through emotions, but in this series, it highlights the sense of sincerity that has already occurred in her married life.

Fractal Characteristics and Energy Evolution Analysis of Rocks under True Triaxial Unloading Conditions

To investigate the mechanical properties and energy evolution laws of rocks under true triaxial unloading conditions, a study was conducted using a true triaxial rock testing system on three different types of rocks: coal, sandy mudstone, and siltstone. The study examined the mechanical behavior, failure patterns, and fractal dimensions of these rocks under true triaxial unloading conditions. The tests revealed significant variations in stress–strain curves and failure patterns among the different rock types. Observation indicated that rocks with lower peak strength exhibited higher fractal dimensions and increased fragmentation upon failure. Subsequently, based on the experimental data of siltstone, the impact of the unloading rate and particle size distribution on the energy evolution under true triaxial single-sided unloading paths was further investigated using the three-dimensional particle flow software PFC3D 6.0, revealing the micro-mechanisms of rock energy evolution. The study revealed that when the initial stress unloading level was low, the total energy and strain energy at the peak strength exhibited a strong linear relationship with the unloading rate. Before the stress peak, the dissipative energy was mainly composed of frictional energy. After the stress peak, the dissipative energy consisted of frictional energy, damping energy, and kinetic energy. The heterogeneity of rock significantly affected the distribution of dissipative energy, with an increase in rock heterogeneity leading to a decrease in frictional energy and an increase in kinetic energy.

Deep learning-based analysis of true triaxial DEM simulations: Role of fabric and particle aspect ratio

This study investigates the influence of micro-scale entities such as inherent and induced fabric anisotropy on the stress–strain behaviour of granular assemblies. In tandem with this exploration, our objective is to formulate a novel correlation that quantifies the evolution of fabric tensor across diverse loading paths. This correlation can be introduced to enhance the micro-mechanical insights in conventional constitutive models. Employing the Discrete Element Method (DEM), we simulate the drained and undrained responses of 680 transversely isotropic particulate assemblies with diverse initial fabrics and particle Aspect Ratio (AR) under true triaxial loading conditions. We consider a second-order fabric tensor based on inter-particle contact orientations to trace fabric evolution during loading. To account for fluid–solid interaction under undrained conditions, we adopted the DEM-Coupled Fluid Method (CFM). The simulation results highlight the significant influence of the Lode angle, particle shape and initial fabric on the stress–strain behaviour of granular materials, with fabric evolution primarily affected by the stress state, void ratio and particle AR. Lastly, we propose a new correlation for the quantification of the fabric tensor using a multi-layer feed-forward neural network. The satisfactory performance of the suggested correlation is demonstrated through a comparison between DEM data and predicted fabric tensor values.

Study on the directional extension law of hydraulic fractures induced by pre-cast slot under tru-triaxial

Directional hydraulic fracturing technology serves as an effective means to overcome the stress constraints in deep coal mines and achieve targeted depressurization and permeability enhancement in specific areas. This study conducted directional hydraulic fracturing tests on samples with pre-cast slots under true triaxial conditions. Considering the azimuth angle (i.e., the angle between the long axis of the pre-cast slot and the maximum principal stress) and long axis length, the stress distribution along the fracture edge was determined using the method of complex variable function, and the evolution mechanism of the stress distribution along the fracture edge was investigated. The main conclusions are as follows: Experimental results indicate that the initiation pressure and directional extension effectiveness show a relative growth pattern of “slow-fast-slow” in the azimuth angle range of 30° to 90°, with the most significant decrease in initiation pressure occurring around 45°, and the enhancement trend of directional extension is most pronounced in the range of 45° to 60°. When the ratio of the long axis to the short axis of the pre-cast slot changes from 2:1 to 1:1 and 3:1, the initiation pressure increases by −30.44% and 28.08% respectively, while the amplification of directional extension effect is −74.6% and 166.8%. Considering the azimuth angle, an expression for the circumferential stress at the edge of the pre-cast slot was derived, and a criterion for determining the initiation of the pre-cast slot edge was proposed. As the azimuth angle increases from 0° to 90°, the circumferential stress at the edge of the pre-cast slot fluctuates, which is consistent with the trend of initiation pressure observed in the experimental results. As the long axis length increases, the initiation pressure decreases, and the initiation position moves closer to the tip.