Internal Mechanism Research Articles

Numerical modeling of cavity collapse water hammer in pipeline systems: Internal mechanisms and influential factors of transient flow and secondary pressure rise dynamics

This study explores the dynamics of pressure wave propagation and cavitation in pressurized pipelines during and after the rapid closure of the pipeline's end ball valve, utilizing a three-dimensional computational fluid dynamics approach with the method of characteristics, validated against Bergant and Simpson's experimental data of three degrees of cavitation. It innovatively examines transient pressure dynamics through both energy transformation and wave propagation perspectives, focusing on the phases of water column separation and coalescence, and the dynamics of flow interruption bubbles. The research delves into the detailed mechanisms of pressure wave propagation and further assesses the effects of physical factors. Key findings include: (1) As initial inlet velocities increase, cavitation starts earlier, extends further, and intensifies, with higher final volume fractions near the valve, indicating that higher velocities exacerbate cavitation. Higher inlet velocities also correlate with more intricate and expansive vortex formations. (2) Secondary pressure surges in water hammer result from the superposition of two-stage positive pressure waves. Initially, positive pressure waves within the conduit reflect twice from air pockets and the upstream boundary, remaining positive. Subsequently, they interact with secondary positive pressure waves reflected by the valve, causing a secondary pressure surge. (3) The fluid flow is laterally symmetry in the pipe cross section, except for minor local asymmetrical spikes in areas with vapor bubbles. Velocity discrepancies are notable near the pipe walls due to vapor accumulation, primarily on the upper wall due to buoyancy. This accumulation may narrow the flow area, possibly accelerating the water passing by. (4) Lower flow velocities, downward inclines, and slower valve closures diminish secondary pressure rise amplitudes in water hammer events, while reduced static heads intensify cavitation despite lessening pulse amplitudes. These findings offer valuable insights for the design and operational guidance of complex hydraulic systems during transient processes in urban water supplies.

Chemical Mapping of Temperate Sub-Neptune Atmospheres: Constraining the Deep Interior H2O/H2 Ratio from the Atmospheric CO2/CH4 Ratio

Understanding the planetary envelope composition of sub-Neptune-type exoplanets is challenging due to the inherent degeneracy in their interior composition scenarios. Particularly, the planetary envelope’s H2O/H2 ratio, which can also be expressed as the O/H ratio, provides crucial insights into its original location relative to the ice line during planetary formation. Using self-consistent radiative transfer modeling and a rate-based automatic chemical network generator combined with 1D photochemical kinetic-transport atmospheric modeling, we investigate various atmospheric scenarios of temperate sub-Neptunes, ranging from H2-dominated to H2O-dominated atmospheres with equilibrium temperatures (T eq) of 250—400 K. This study includes examples such as K2-18 b (T eq = 255 K), LP 791-18 c (T eq = 324 K), and TOI-270 d (T eq = 354 K). Our models indicate that the atmospheric CO2/CH4 ratio can be used to infer the deep interior H2O/H2 ratio. Applying this method to recent JWST observations, our findings suggest that K2-18 b likely has an interior that is 50% highly enriched in water, exceeding the water content in a 100 × Z ⊙ scenario and suggesting a planetary formation mechanism involving substantial accretion of ices. In contrast, our model suggests that approximately 25% of TOI-270 d’s interior is composed of H2O, which aligns with the conventional metallicity framework with a metallicity higher than 100 × Z ⊙. Furthermore, our models identify carbonyl sulfide (OCS) and sulfur dioxide (SO2) as strong indicators for temperate sub-Neptunes with at least 10% of their interior composed of water. These results provide a method to delineate the internal composition and formation mechanisms of temperate sub-Neptunes (T eq < ∼ 500 K) via atmospheric characterization through transmission spectroscopy.

Integrated Network Pharmacology and Molecular Docking to Explore the Mechanisms of Ningshen Wendan Decoction in the Treatment of Schizophrenia.

Schizophrenia (SCZ) is a prevalent chronic mental disorder characterized by a high recurrence rate and significant disability. Currently, no satisfactory pharmacological treatments have been identified. Although Ningshen Wendan decoction (NSWDD) has shown promising results in improving cognitive function in patients with schizophrenia, its underlying mechanism of action remains unclear. This study systematically investigated the mechanisms of NSWDD in SCZ treatment using network pharmacology and molecular docking approaches. Analysis of the interaction genes revealed 307 common targets of NSWDD and SCZ. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses indicated the involvement of multiple signaling pathways including interleukin 17 signaling pathway, multiple virus infections, Advanced glycosylation end products (AGEs) - receptor of AGEs (AGEs-RAGE) signaling pathway, tumor necrosis factor signaling pathway, and Hypoxia-inducible factor-1 (HIF-1) signaling pathway as key pathways influenced by NSWDD in treating SCZ. These pathways are associated with various biological processes such as transcriptional regulation, apoptosis regulation, gene expression regulation, and external stimulus-response. Molecular docking simulations indicated favorable binding interactions between components of NSWDD and target proteins via intermolecular forces. The study provided initial insights into the internal molecular mechanisms underlying the beneficial effect of NSWDD on SCZ through multi-target modulation across multiple pathways.

Simulation study of the effect of electrode polarity on microscale corona discharge characteristics

Abstract The occurrence and application scenarios of micro-scale corona discharge are diverse, and the effect of micro-scale corona discharge mechanism and needle electrode polarity on corona discharge characteristics is still unclear. This paper establishes a microscale simulation model of pin-plate DC positive and negative corona fluid chemical reactions. The phenomenon of positive and negative corona discharge is being investigated. The internal discharge mechanism is analyzed from the microscopic point of view. Results demonstrate that positive corona discharge generates space charges that reduce the electric field strength between the needle electrode and amplify it between the plate electrodes. In contrast, negative corona discharge exhibits the opposite effect. The number of charged particles produced by microscale negative corona discharge is larger than that produced by positive corona, and the discharge phenomenon is more intense than that of positive corona. Under the simulation conditions in this paper, the ionization reaction rate of micro-scale positive and negative corona rises rapidly at the initial discharge. It will gradually remain stable after experiencing an upward pulse. The pulse peak value generated by micro-scale negative corona discharge is much higher than that of positive corona, and the pulse width of negative corona discharge is about half smaller than that of positive corona, which can reach a stable corona discharge state faster.

Visual depiction and numerical characterization of intricate flow in triply periodic minimal surface foams

Benefiting from the structural specificity and programmability, the bioinspired triply periodic minimal surfaces (TPMSs) bring excellent physicochemical properties that are distinct from conventional topologies. Especially with the rapid development of additive manufacturing and high-performance computing capacities, function-oriented design and synthesis of smart TPMS materials or devices have become feasible. Therefore, understanding the flow characterizations induced by TPMS foams is of remarkable importance to the successful design and practical operation. However, the in-depth studies and theoretical guidance on the relationship between structure and flow characterizations of TPMS foams are still limited. In this study, an Eulerian and Lagrangian coupled model is developed to investigate the internal flow behaviors and flow regime transition mechanism from creeping to inertial flow in four representative TPMS foams. The simulation accuracy is then validated by a high-resolution pore-scale flow field observation. Results show that the flow morphology and pressure drop characteristics are highly influenced by TPMS geometry and Re. Among which, Schwarz Diamond (D), Schoen Gyroid (G), and Fischer-Koch S (S) foams are more susceptible to radial flow disturbance, while Schoen inverted Weissenberg periodic foam to axial flow disturbance. In addition, higher porosities delay the transition to transitional regime of the flow. This work establishes firm theoretical and methodological foundations for the customization and intelligent development of bioinspired TPMS foam materials in broad fluidic applications.

INFLUENCE OF INFORMATION TECHNOLOGY ON INTERNAL CONTROL SYSTEMS IN TERTIARY INSTITUTIONS IN OSUN STATE, NIGERIA

The study examined how information technology affects internal control systems in tertiary institutions in Osun State. Specific goals were to ascertain whether or not information technology has a significant impact on the internal control systems and internal audit processes of tertiary institutions. A survey research design was chosen. A sample size of 100 respondents participated in the study. This study used the stratified sampling method and a regression technique was used for data analysis. The findings showed that internal control systems and internal audit procedures in tertiary institutions in Osun State were highly influenced by information technology with t= 20.02 P&lt; 0.0 and t= 19.049p&lt;0.05, respectively. It was concluded that internal control systems and internal audit procedures at tertiary institutions were strengthened and improved by information technology. The study has recommended that tertiary institutions adopt information technology in order to improve their internal control frameworks. To keep their staff’s necessary skills and knowledge current, the management of tertiary institutions should encourage both on-the-job and off- the-job training in information technology. To stop fraud, internal control mechanisms should be put in place. To establish who will be held accountable for violations, tasks must be digitally separated effectively.

Minimum levels of interpretability for artificial moral agents

AbstractAs artificial intelligence (AI) models continue to scale up, they are becoming more capable and integrated into various forms of decision-making systems. For models involved in moral decision-making (MDM), also known as artificial moral agents (AMA), interpretability provides a way to trust and understand the agent’s internal reasoning mechanisms for effective use and error correction. In this paper, we bridge the technical approaches to interpretability with construction of AMAs to establish minimal safety requirements for deployed AMAs. We begin by providing an overview of AI interpretability in the context of MDM, thereby framing different levels of interpretability (or transparency) in relation to the different ways of constructing AMAs. Introducing the concept of the Minimum Level of Interpretability (MLI) and drawing on examples from the field, we explore two overarching questions: whether a lack of model transparency prevents trust and whether model transparency helps us sufficiently understand AMAs. Finally, we conclude by recommending specific MLIs for various types of agent constructions, aiming to facilitate their safe deployment in real-world scenarios.

Impact of Yb2+ on the anti-Stokes fluorescence cooling performance of Yb-doped silica fibers

To unlock the full potential of laser-cooled silica optical fibers, a better understanding of the internal mechanisms of heat generation is required. This work explores ytterbium-doped aluminosilicate fibers produced via industry-standard modified chemical vapor deposition (MCVD) techniques with varied levels of divalent ytterbium to determine their effect on anti-Stokes fluorescence thermal performance. The inclusion of Yb2+ is shown to have a significant negative impact on cooling potential. Yb2+ ions are shown to correlate with heat generation by two distinct mechanisms, absorption and quenching of active Yb3+ ions. This excess heating represents a reduction in quantum efficiency that is detrimental to Yb-doped fiber lasers and amplifiers beyond the laser-cooling application.

Optimizing the Size of a Moving Annular Hollow Laser Heat Source

The physical phenomenon of the annular hollow laser surface treatment process is complex, and the internal mechanism involves multiple disciplines and fields. In addition to the general parameters of laser beams, such as laser power and scanning speed, an annular hollow laser beam exhibits unique physical characteristics, including hollow ratio and hollow area. The selection of the inner and outer annular radii of the laser plays a critical role in the study of metal surface heat treatment. From the point of view of heat transfer, the entransy dissipation theory is introduced in the metal surface treatment process with an annular hollow heat source. Firstly, using the principle of the extreme value of the entransy dissipation rate, under a constant heat flux boundary condition, the entransy dissipation rate is obtained through the temperature field distribution in the calculation area by numerical simulation. Secondly, the selection of the inner and outer ring radii of the annular laser is explored, and the average temperature difference of the heating surface is minimized to reduce the thermal stresses of the material. This paper seeks new insights into the geometric parameters of the inner and outer radii of the annular heat source.

Evolution characteristics of calcareous sand force chain based on particle breakage

Abstract Calcareous sand is easily broken under external force, which brings great difficulties to island reef engineering. Based on the particle flow program, a discrete element model that can reproduce the results of laboratory tests is established, the large principal stress method is introduced to identify the particle force chain, and the bond strength between particles is increased to obtain an unbreakable model with the same initial conditions, and different confining pressures are compared and analyzed. The evolution law of the force chain of the following two models establishes a macro-meso cross-scale analysis in the deformation process of calcareous sand, explores the internal mechanism of the crushing of calcareous sand particles. The results show that particle breakage plays an important role in the evolution of the force chain. Particle breakage will reduce the probability of the force chain on both sides of the axis, forcing the probability of the axial force chain to rise steadily. The macroscopic deviatoric stress is the external manifestation of the probability of the axial force chain on the meso level. The faster the probability of the force chain in the direction of the potential shear band increases, the more obvious the shear band is.

Analyzing resilience influencing factors in the prefabricated building supply chain based on SEM-SD methodology

The supply chain for prefabricated buildings (PB) currently grapples with pressing challenges. In order to ensure the safe and stable development of the prefabricated building supply chains (PBSC), this study aims to identify the key factors and internal mechanisms affecting the PBSC, and propose a supply chain resilience enhancement mechanism, so as to promote the sustainable development of the PB industry. The study combined a literature review and survey data to identify key resilience factors in PBSC. A Structural Equation Model (SEM) was used to explore the relationships between these factors. System dynamics were applied to create a simulation model, assessing the resilience impact level and conducting sensitivity analysis. The results show that the transportation and procurement processes are the most significant factors influencing supply chain resilience. The external environmental factors wielded a more pronounced impact on the overall evaluation of supply chain resilience than the delivery and use processes, but delivery and use processes are more sensitive. The study uses the Pressure-State-Response (PSR) model to suggest strategies for enhancing supply chain resilience. This study contributes to more sustainable and efficient construction practices by offering an innovative theoretical framework to analyze the factors influencing PBSC resilience and proposing enhancement strategies.

Females in Corporate Board Diversity and Its Impact on Earnings Quality

Earnings quality is formed on corporate governance. The company's internal governance mechanism consists of the president director, the finance director, the board of directors, commissioners, and the audit committee. However, there is still a lack of studies exploring the relationship between female in-board diversity and earnings quality, especially in Indonesia. It is because Indonesia has a unique corporate governance system, even though Indonesia follows a corporate governance system on the European continent, namely the two-tier boards. This study aims to determine the influence of female president directors, female finance directors, female board of directors, female board of commissioners, and female audit committee on earnings quality. The sample of this study is manufacturing companies listed on the Indonesia Stock Exchange. Samples were selected using the purposive sampling method, and 70 companies were selected as research samples with a total data collection of 350 data from the research period of 2018-2022. Data analysis in this research uses multiple linear regression. The results of this study indicate that the presence of a female president director, a female finance director, and a female board of commissioner negatively affects earnings quality. On the other hand, the presence of the female board of directors has a positive effect on earnings quality. The female audit committee does not affect earnings quality. The author can conclude that the female gender still does not play an important role in the company's management to increase earnings quality because female’s behavior is more callous and not more assertive than male.

Does Sino-US trade friction hurt corporate resilience? Evidence from Chinese enterprises

As the world’s largest foreign trading country, China has faced numerous trade investigations in recent years. We select panel data from China’s manufacturing A-share listed companies from 2012 to 2021 to explore the impact of Sino-US trade friction on corporate resilience and its internal mechanisms. The results show that: (1) The intensification of Sino-US trade friction significantly reduces the resilience of Chinese microenterprises. This conclusion remains robust after a series of tests using PSM-DID and other methods. (2) Heterogeneity analysis shows that the resilience of export enterprises, high-tech enterprises, and enterprises in developed regions are more severely impacted by Sino-US trade friction. (3) Mechanism tests reveal that Sino-US trade friction damages enterprise resilience mainly through three channels: damaging the spirit of entrepreneurs, reducing internal operating profits, and exacerbating external financing constraints. The results provide theoretical and empirical support for understanding the survival effects of microeconomic entities under the impact of Sino-US trade friction.

The Internal Structure and Influence Mechanism of Double Qualified-Teachers’ Quality and Competence

The Internal Structure and Influence Mechanism of Double Qualified-Teachers’ Quality and Competence

Thermo-hydro-mechanical coupling in oil shale: Investigating permeability and heat transfer under high-temperature steam injection

Steam convective heating emerges as a sustainable and effective method for extracting oil shale, where understanding the temperature-dependent evolution of its pyrolytic characteristics, microstructure, and permeability is vital for efficient resource extraction. Through a stress-sensitive micro-CT scanning and a high-temperature and pressure triaxial test apparatus, this research utilizes Balikun oil shale samples to investigate the changes in microstructure and gas production from 20 °C to 550 °C. The study integrates theoretical analysis and numerical simulations to uncover the fundamental connections between internal permeability and heat transfer mechanisms during steam injection. It reveals that oil shale undergoes two critical evolutionary phases: a stability phase below 350 °C, where volatile dispersion occurs, and a rapid increase phase above 350 °C, marked by significant microstructural changes from micro-fractures to extensive through-going fractures due to intense thermal decomposition. This decomposition leads to increased gas production and enhanced thermal fracturing. The threshold temperature is identified at 400 °C, above which the oil shale's mechanical strength and pore pressure increase, leading to decreased volumetric compression until stabilization. These findings demonstrate that higher temperatures enhance fracture connectivity and steam flow, optimizing the heating efficiency in oil shale extraction.

Preparation and anti-counterfeiting application of Sr3Y2Ge3O12:Bi2+ red long afterglow luminescent

Red, as one of the three primary colors, is crucial for blending the luminescent color of long-lasting materials. This project selected Sr3Y2Ge3O12 as the substrate and Bi2+ as the activator. A solid-state method at high temperature was used to prepare a new type of visible red long-afterglow luminescent material, by adjusting the doping concentration of Bi2+ and changing the calcination temperature. When the doping concentration of Bi2+ was 0.50mol% and the calcination temperature was 1150 °C, the prepared Sr3Y2Ge3O12:Bi2+ had the best luminescent properties. After being excited by 254 nm ultraviolet light, the material shows the red afterglow luminous intensity, duration and stability that meet the practical application requirements. Through thermoluminescence, photoluminescence and fluorescence spectra, the trap characteristics and internal mechanism of long afterglow were studied comprehensively. Finally, the film and printing ink were prepared by using the Sr3Y2Ge3O12:Bi2+ long afterglow luminescent powder with the best luminescent performance, and the pattern anti-counterfeiting was successfully realized.

Evolutionary pathways of disk galaxies with different sizes

This work delves into the complex interaction between disk galaxies and their host dark matter halos. It specifically focuses on scenarios with minimal external ("nurture") influences such as mergers and substantial tidal interactions. The study uncovers the varied evolutionary paths of disk galaxies of different sizes, shaped by the initial conditions of their parent dark matter halos and subsequent internal processes. Thus, we can explore the ``nature'' of these galaxies. From the TNG50 simulation, a sample of 836 central disk galaxies with tiny stellar halos is chosen to study the inherent evolution of galaxies driven by nature. These galaxies are classified as compact, normal, or extended by referencing their locations on the mass-size ($M_ $) diagram. Scaling relations were then established to measure the correlations driven by internal mechanisms. This research demonstrates the distinctive evolutionary pathways of galaxies with different sizes in IllustrisTNG simulations, primarily driven by their nature. It is confirmed that disk galaxies inherit the angular momentum of their parent dark matter halos. More compact galaxies form earlier within halos that exhibit a lower specific angular momentum through heightened star formation during the early phase at redshifts above 2. During the later phase, the size of extended galaxies experiences more pronounced growth by accreting gas with a high angular momentum. Additionally, we reveal that many key characteristics of galaxies are linked to their mass and size: (1) compact galaxies tend to exhibit higher metal content, proportional to the potential well, $ M_ star R_ $; (2) compact galaxies host more massive bulges and black holes, along with a higher central concentration. Furthermore, our analysis indicates that galaxies of all types continue to actively engage in star formation, with no evident signs of quenching attributed to their varying sizes and angular momenta.

Subjective Understanding is Reduced by Mechanistic Framing.

People often believe that they have a good understanding of how devices work (e.g., how a ballpoint pen works), despite having poor knowledge of their internal mechanics. We hypothesized that this bias occurs in part because people conflate mechanistic understanding with functional understanding of how devices work (e.g., how to operate a ballpoint pen). In two experiments, we found that increasing the salience of mechanistic information led to lower judgments of understanding for how devices work. In Experiment 1, we did this by showing participants either the internal parts of a device or an external, whole-object view of that same device. Those who saw the internal parts rated their understanding as less than those who saw a whole-object view. In Experiment 2, we removed the pictures and instead tested participants (without feedback) on their mechanistic or functional knowledge using true-or-false questions. Those who were tested on mechanistic knowledge rated their understanding of devices as less than those who were tested on functional knowledge.

The Relationship Between Corporate Social Responsibility and Consumers’ Purchase Intention with the Intermediary Variable of Altruistic Attribution

With the rapid development of the current market economy of China, corporate social responsibility had gradually begun to be taken into one of the factors that determine their purchase intention for the consumers when they purchased the products. At present, most of the researchers were about exploring the impact of corporate social responsibility on the final behaviour of the consumers, but the internal mechanism of corporate social responsibility that affected the behaviour of consumers was relatively rare. Based on the attribution theory, the mediation model with moderation to study its internal mechanism had been constructed in this research, also the methods of questionnaire survey were used to the empirical test for the conceptual model in this research. The results of the study showed that the corporate social responsibility had a direct positive impact on the purchase intention of the consumers, also it had an indirect positive impact on the purchase intention of consumers that through the altruistic attribution; The perceived effectiveness of consumer would positively regulate the influence of the corporate social responsibility on altruistic attribution; while the corporate social responsibility-corporate ability beliefs would negatively affect the relationship between altruistic attribution and purchase intention of consumers. Finally, the suggestions had been put forward for the results obtained by the survey in this research, which could be taken as reference for the academic community and the industry.

Multilevel regulation of lactose operon in Bacillus licheniformis: Coordination of LacR, CcpA and TnrA regulators

Previous research has confirmed the involvement of the lac1 gene cluster in lactose metabolism in Bacillus licheniformis, which is able to co-utilize lactose and low concentrations of glucose or certain carbon sources. However, the internal regulatory mechanisms underlying specific lactose utilization remain elusive. In this study, we conducted a comprehensive investigation to elucidate the modulation mechanism of the lac1 gene cluster. We discovered a 162 bp bidirectional promoter located between the lacDCAB and lacR genes, which encodes a GntR family transcriptional regulatory factor. A 38 bp perfectly palindromic sequence (BOX1) within this promoter is critical for inducing lac1 expression. LacR and CcpA were shown to bind specifically to BOX1, and their novel binding motifs were identified. In BL2ΔlacR, BL2ΔccpA, and BL2ΔlacRΔccpA mutant strains, we confirmed the differential inhibitory levels of LacR and CcpA on bidirectional promoters. Furthermore, it was demonstrated that TnrA also binds BOX1 and exerts a positive regulatory effect on the lac1 cluster. Finally, we proposed a novel model to unravel the complex molecular interactions controlling the expression of the lac1 gene. These insights provide a foundation for exploring rational design strategies to optimize lactose fermentation processes and improve the efficiency of industrial lactose utilization.