Effect Of Pressure Research Articles

Effects of hydrostatic pressure, aluminium composition, and external magnetic field on intersubband and intrasubband transitions characteristics in symmetric potential quantum wells

Aluminium composition (λ), magnetic field (B), and hydrostatic pressure (P) influences on magneto-optical (MO) properties of intra- and inter-subband transitions in GaAs/AlλGa1−λAs symmetric QWs for four models of confined optic phonons are studied and compared. The findings indicate: the MO characteristics of intra- and inter-subband transitions are significantly influenced by B, λ, and P for phonon absorption and emission. The e–p interaction intensity decreases as P increases, whereas it increases as λ increases. The influences of λ and P on phonon absorption are more significant than those on emission. E–p interaction intensity dependence on λ and P for intra-subband transitions is stronger than that for inter-subband ones. The e–p interaction in QWs is well described by Knipp–Reinecke and Huang–Zhu models. To reduce the influence of P on MO properties, we can increase T and λ or decrease B. At T≈600 K, the influence of P is insignificant and can be neglected.

Time-Dependent Reliability Analysis of Anhydrite Rock Tunnels under Swelling Conditions: A Study on Stress, Deformation, and Engineering Solutions

This study presents an analytical approach for evaluating the reliability of anhydrite rock tunnels, focusing on their characteristic swelling behavior. Anhydrite rocks, prone to significant expansion upon moisture exposure, pose a challenge in tunnel construction, potentially leading to structural issues such as floor heave and lining damage. To address this, this research develops an elastic swelling analytical solution based on humidity stress field theory, enabling the assessment of time-dependent stress and deformation changes in anhydrite tunnels. The solution’s applicability is demonstrated through its application to the Lirang tunnel. The investigation into the effects of support pressure, swelling time, and reserved deformation on tunnel reliability reveals that circumferential stress at the tunnel wall increases by 13.94% and 21.86% for swelling periods of 30 and 365 days, respectively. Similarly, radial displacement escalates by 22.97% and 35.93% over these periods, highlighting the significant impact of swelling behavior. Using a spreadsheet-based First Order Reliability Method (FORM) for analysis, this study finds that the original design of the Lirang tunnel did not meet the desired reliability standards under swelling conditions. However, strategic adjustments in construction variables, such as increasing support pressure to 1.2 MPa or enhancing reserved deformation to 59 mm, elevated the tunnel’s reliability to meet safety requirements. This research provides a vital framework for assessing and enhancing the reliability of anhydrite rock tunnels, considering the long-term effects of swelling. It underscores the importance of incorporating swelling behavior in the design and construction of tunnels in anhydrite rock formations, offering valuable insights for optimizing tunnel stability in such challenging geological conditions.

A new cognitive conservation model for understanding Malaysian birders’ behaviour towards birds

ABSTRACT Birdwatching as a subset of ecotourism can produce recreational disturbance. This research aims to assess the validity and reliability of a formative conservation model regarding disturbance behaviour towards birds. This model uses cognitive theories to identify the key factors influencing behavioural intention towards disturbance behaviour on birds among Malaysian birdwatchers. We present the theory of planned behaviour (TPB), the theory of normative conduct, and the cognitive hierarchy model in the Predictor Bird Conservation Model (PBCM). The data was collected from 421 Malaysian birdwatchers using a field survey. The model was tested using the partial least squares (PLS) approach. This model provides managerial implications for determining the cognitive influential factors on intention towards target behaviour. Ten hypotheses are proposed and tested. The results showed subjective norms (SN) had the greatest substantial variance among other predictors of the study model. However, attitude and perceived behaviour had the lowest variance towards the intentions for target behaviour. The study contributes to existing literature regarding the implication of the TPB. This research also focuses on non-consuming behaviour which is considered critical for its potential for social pressure effect.

The effect of shareholder pressure on stakeholder interests: Evidence from corporate tax avoidance

AbstractResearch on how shareholder pressure influences the interests of stakeholders has recently witnessed a sharp increase, but yields mixed findings. We revisit this question by investigating the impact of managers' attempts to meet or beat earnings expectations on corporate tax avoidance. Using a sample of Chinese listed firms during 2005–2022, we find that firms with earnings pressure are more tax‐aggressive. Furthermore, such a higher level of tax avoidance due to earnings pressure is associated with higher real activity management. Cross‐sectional analysis shows that the effect of earnings pressure on tax avoidance is weaker among firms with better environment, society, and governance performance, but becomes more salient for state‐owned enterprises, firms with higher financial constraints, and during periods when local officials are devoid of incentives for career advancement. Taken together, our study sheds light on the consequences of shareholder pressure stemming from capital markets on corporate tax policies, and provides implications for enterprises and policymakers concerning taxation in emerging markets.

Theoretical study of the anharmonic effect on the main reactions in the combustion mechanism of methanol

The harmonic and anharmonic rate constants, kinetic and thermodynamic parameters of the important reactions of the combustion mechanism of CH3OH are calculated from 300 K to 4000 K. Furthermore, the effect of pressure and tunneling effect are considered in this paper. The calculations indicate that the bimolecular reaction exhibits a particularly obvious anharmonic effect than the unimolecular reaction. The calculated anharmonic rate constants are more in line with other theoretical or experimental results. In summary, these calculations complement the basic database of methanol, thereby improving the accuracy of the combustion reaction mechanism.

Development of a HPLC system using a phase-separation multiphase flow as an eluent: an influence of column pressure on phase separation and chromatogram at room temperature.

We have developed a HPLC system where phase-separation multiphase flow works in the separation column as an eluent. We call the novel separation mechanism a phase-separation mode. The ternary mixed solution of water/acetonitrile/ethyl acetate, which is one of the two-phase-separation mixed solutions, caused the phase-separation multiphase flow via phase change from homogeneous to heterogeneous with the temperature effect (from 20 to 0°C). In this study, we tried to perform phase-separation multiphase flow with the pressure effect instead of the temperature one. The fused-silica capillary tube (50cm length and 50µm inner diameter) was allied to the downstream of the column to apply the pressure of 5.5MPa to the system. Model analytes of 2,6-naphthalenedisulfonic acid (2,6-NDS) and 1-naphthol (1-NA) were examined. For example, solutions (the volume% of water/acetonitrile/ethyl acetate; 20:55:25, organic-rich) and (60:30:10, water-rich) were used as eluent. The model analytes were not separated with both solutions at the pressure of 1.5MPa and 20°C. But with the organic-rich solution, 1-NA and 2,6-NDS were separated in this order and with the water-rich solution, they were separated in the reverse order at the pressure of 5.5MPa and 20°C. The phase-separation mode could be performed at the high pressure even at the room temperature.

Moderate of audit committee on components of the fraud hexagon theory and fraudulent financial statements

This study aims to analyze the effect of each component of the fraud hexagon theory on fraudulent financial statements with the audit committee as a moderator. This research was conducted at banking sector companies listed on the IDX in 2019-2022, totaling 47 companies. The sampling method uses purposive sampling which results in 44 companies with 176 financial data used as samples. Data analysis was carried out on secondary data with SEM-PLS analysis techniques. The results of this study indicate that independent commissioners who hold concurrent positions, the ratio of total accruals to total assets (TATA) and ineffective monitoring have no effect on fraudulent financial statements. External pressure has a negative effect on fraudulent financial statements, while changes in directors and managerial ownership have a positive effect on fraudulent financial statements. The audit committee is able to moderate the effect of external pressure, change of directors, managerial ownership and ineffective monitoring on fraudulent financial statements. The audit committee is unable to moderate the effect of independent commissioners who hold concurrent positions, the ratio of total accruals to total assets (TATA) on fraudulent financial statements.

Apply frequency response function schemes for damage detection in composite nanoscale-pipes under transient conditions

Knowledge of Nanoscale-structures sustainability is strongly associated with the reliability and the performances of Nano-electro-mechanical systems such as Nanoactuators and Nano-sensors that are widely used in bio-applications. Therefore, the damages in these types of infinitesimal systems must be quickly and accurately detected, located, and repaired. In this study, a novel damage detection framework in Carbon Fiber Reinforced Polymer (CFRP) composite Nanoscale-Pipes (CNP) subjected to the fatigue effect of water internal pressure and thermal effect via Nanoscale-electrical capacitance sensors (NECS). First, a finite element model (FEM) of CNP damage is established, then the electrical potential difference (EPD) between the Nanoscale-electrodes (NEs) pairs before and after damage is measured. The distributed NECS measuring nano-electrodes are installed around the CNP and load the transient external excitations between each other. It is proposed and applied the transfer function (TF) of the CNP as an "open loop control" system to reflect the evolution of damage. The accuracy and reliability of the suggested technology are verified through the experimental results available in the literature. The results show that when the damage under NEs pairs has begun to grow, the signal amplitude value will change suddenly and sensitively, which demonstrates the effectiveness of the proposed method and the good potential for engineering applications.

Effect of a harmonic surface pressure on wave propagation over a beach

The objective is to study the harmonic forced wave motion over a beach by a finite Fourier transform technique. The constructed approximate solution has a logarithmic singularity at the shoreline. It accounts for reflexion and local perturbations. Trapping of waves may take place for particular choices of the applied surface pressure excess. The case of a wave incident against a cliff with horizontal bottom is solved exactly. The method deals invariably with a variety of bottom shapes, including the case where there is an additional corrugation of the bottom on a finite interval. Other bottom boundary conditions than impermeability can be treated as well. The results may be of interest in several practical applications, in particular the evaluation of the reflected wave. Numerical applications for a plane sloping beach, a parabolic-type beach and a shelf-type beach are presented and the systems of streamlines have been drawn over and in the proximity of the beach.

Experimental Investigation on a Water Diversion Shield Segment Using a Newly Developed Model Test Chamber

Jinan City in China is known for its abundant spring water, and the protection of underground spring water transport channels is a key issue that needs to be paid attention to in Jinan subway construction. In areas where underground spring water transport channels are easily disturbed, when the shield tunnel passes through a composite formation with a permeable layer in the middle and an impermeable layer in the upper and lower parts, the underground spring water transportation channel is blocked, the spring veins are damaged, and the underground spring water is blocked in the upstream, resulting in an increase in the water pressure difference on both sides of the tunnel. In this paper, based on the working principle of a new type of pipe segment with a diversion function, a diversion function pipe model test box is designed and fabricated. Using this model box, the working state of the diversion function pipe segments is simulated. An earth pressure box and pore water pressure gauges are embedded in the model box to measure the earth pressure and pore pressure around the pipe under seepage unsymmetrical pressure. Strain gauges are attached in a circular shape on the inner side of the pipe to measure and calculate the strain and stress of the pipe. Through model tests, the effective repair of the diversion pipe on blocking groundwater flow and the relief effect of the unsymmetrical pressure of the pipe are verified.

Anthropic pressure drives resource selection of an adaptable generalist in human‐dominated landscapes

AbstractFew landscapes on earth remain free of human‐modification, which may influence resource selection in wildlife. To investigate the effects of anthropic pressure on wild boar (Sus scrofa) and explore management implications, we studied how diel resource selection of the species' main life stages changed with spatial variations of human access (e.g., for recreation), temporal changes in hunting pressure, and habitat type. Using 206,461 hourly GPS‐locations of 15 males, 11 females with dependent young, and 17 other females from south‐western Germany, we found anthropic pressure influenced resource selection more than ecological factors. All boars were more likely to select for low human‐access areas than high human‐access areas, regardless of habitat. Hunting pressure was most avoided by females with dependent piglets, followed by males and other females. Since both hunting activity and general human access affected resource selection, they should be considered simultaneously in wildlife management and conservation. We suggest the further establishment of wildlife reserves that are inaccessible to people where boar may remain more localized, thereby reducing the risk of disease transmission, and boar hunting to focus on open lands and refuge boundaries to reduce crop damage. This may also benefit overall human‐wildlife coexistence, animal welfare, and biodiversity conservation in anthropized environments.

Underlying Effects of Temperature and Pressure on the Concentration of Carriers and Intrinsic Defects in the Bi2MoO6 Photocatalyst: A Hybrid Density Functional Study

Underlying Effects of Temperature and Pressure on the Concentration of Carriers and Intrinsic Defects in the Bi₂MoO₆ Photocatalyst: A Hybrid Density Functional Study

Understanding impulse buying in E-commerce: The Big Five traits perspective and moderating effect of time pressure and emotions

Impulsive buying behavior is crucial for understanding the psychological dynamics of consumer purchasing in the online marketplace. Identifying antecedents and moderating factors is vital to comprehensively understanding impulsive buying behavior. This research explores the influence of the Big Five personality traits on impulsive buying behavior in e-commerce settings and investigates the moderating effects of time pressure and emotions on these relationships. Data was collected through online questionnaires from 342 Indonesian participants with e-commerce purchasing experience. Structural Equation Modeling was utilized to validate the research hypotheses. The findings reveal that personality traits such as agreeableness, openness to experience, extroversion, and conscientiousness significantly drive impulsive buying behavior in e-commerce. Additionally, the study highlights that the interaction between emotions and neuroticism, as well as time pressure and agreeableness, significantly impacts impulsive buying behavior. The findings contribute valuable theoretical insights by demonstrating how specific Big Five personality traits influence impulsive buying behavior, while also providing practical implications for e-commerce platforms to effectively manage and leverage time pressure and emotional triggers to enhance consumer engagement and drive impulsive purchases.

Length-weight relationship and condition factor of Micralestes eburneensis populations from the Cavally River in Côte d’Ivoire

This study aims to show the effect of anthropogenic pressures on populations of Micralestes eburneensis caught in the River Cavally in Côte d’Ivoire. Sampling took place from April 2015 to May 2017. The fish caught came from experimental and artisanal fisheries. The length-weight relationship and condition factor were determined using the equations P = aLSb and K = 100*P/LS, respectively. A total of 349 individuals with a standard length of between 48 mm and 82 mm and a mass ranging from 3 g to 10 g were caught. The coefficient of determination (r2) values recorded ranged from 0.66 to 0.88. The estimated allometry coefficients for M. eburneensis were 2.81, 2.55 and 2.42 upstream, in the mining zone and downstream respectively. The condition factors of M. eburneensis individuals sampled in the Cavally river fluctuated between 0.66 and 1.39 with a median value of 1.05. The lowest values (K = 0.66 - 0.88) were recorded during the dry season. The size range in the three best-represented sampling areas is between 66 and 74 mm (standard length). This study contributes to our knowledge of the biology of M. eburneensis and provides a specific database on the length-weight relationship and condition factor of the species M. eburneensis from the Cavally River.

Plume active control in high-power fiber laser welding based on high-speed shielding gas microbeam

Plume is an inherent physical phenomenon in fiber laser keyhole welding, negatively affecting welding quality. This paper proposes a new type of high-speed shielding gas microbeam (HSGM) based on the limitation of conventional shielding gas regulating plumes. The gas flow characteristics of the HSGM on the molten pool surface were explored using numerical simulation. Then, the coaxial double-layer shielding nozzle was trial-manufactured to clarify the regulation law for the HSGM on the plume. The gas velocity and pressure produced by the HSGM on the molten pool surface were positively correlated with the shielding gas flow rate, and the gas flow pattern was an acute triangle shape. The suitable HSGM can significantly restrain plume formation, improve the weld surface forming quality, increase the weld penetration depth (about 15.4%), and reduce the mass loss of the weld (about 58.7%). The significant blowing pressure effect of HSGM on plumes and splashes was the key to regulating the welding process. Compared with conventional shielding gas, the use of HSGM was significantly reduced.

Spin crossover iron complexes with spin transition near room temperature based on nitrogen ligands containing aromatic rings: from molecular design to functional devices.

During last decades, significant advances have been made in iron-based spin crossover (SCO) complexes, with a particular emphasis on achieving reversible and reproducible thermal hysteresis at room temperature (RT). This pursuit represents a pivotal goal within the field of molecular magnetism, aiming to create molecular devices capable of operating in ambient conditions. Here, we summarize the recent progress of iron complexes with spin transition near RT based on nitrogen ligands containing aromatic rings from molecular design to functional devices. Specifically, we discuss the various factors, including supramolecular interactions, crystal packing, guest molecules and pressure effects, that could influence its cooperativity and the spin transition temperature. Furthermore, the most recent advances in their implementation as mechanical actuators, switching/memories, sensors, and other devices, have been introduced as well. Finally, we give a perspective on current challenges and future directions in SCO community.

Effect of sintering pressure on microstructure and mechanical properties of (TiB2–SiC)/B4C composite ceramics

Effect of sintering pressure on microstructure and mechanical properties of (TiB2–SiC)/B4C composite ceramics

Influence of gold-selenium precursor ratio on synthesis and structural stability of α- and β- AuSe

Gold selenide (AuSe) is a multilayer compound that has yet to be thoroughly studied. The colloidal synthesis and characterization of gold selenide nanoparticles are described, emphasizing the effect of different gold-to-selenium precursor ratios and temperatures on the crystal structure and form. The structural characterization is done using an X-ray diffraction pattern. The coexistence of the α- and β-AuSe phases is observed in all synthesized samples. Our research indicates that the β-AuSe phase was predominantly found in the AuSe preparation process, which involved the reaction of metallic gold with elemental Se in oleylamine at a 1:1 precursor ratio of Au/Se. On the other hand, the mixed phase, which was dominated by the α-phase, was found in the selenium-rich synthesis, which had a 1:4 precursor ratio of Au/Se. The morphologies of the mainly α-AuSe sample are nanobelts, whereas the primarily β-AuSe phase sample has a nanoplate-like structure, according to the TEM and SEM data. All of the samples had Raman vibrational modes with mixed phases. The effect of high pressure on as-prepared AuSe samples has been studied in this work. The introduction of external pressure and temperature allows both phases to transition. The rising pressure reduces the presence of β-phase in the mixed phase sample, which has a pre-dominating α-phase, leaving only a substantial α-phase in the AuSe sample. The phase transition pressure was observed using Raman scattering. Our findings show that 2D AuSe has a lot of promise for multifunctional applications, encouraging more research on these systems.

Investigate on the mechanical properties and microscopic three-dimensional morphology of rock failure surfaces under different stress states

The macro and micro morphology of rock failure surfaces play crucial roles in determining the rock mechanical and seepage properties. The morphology of unloaded deep rock failure surfaces exhibits significant variability and complexity. Surface roughness is closely linked to both shear strength and crack seepage behavior. Understanding these morphology parameters is vital for comprehending the mechanical behavior and seepage characteristics of rock masses. In this study, three-dimensional optical scanning technology was employed to analyze the micromorphological properties of limestone and sandstone failure surfaces under varying stress conditions. Line and surface roughness characteristics of different rock failure surfaces were then determined. Our findings reveal a critical confining pressure value (12 MPa) that influences the damage features of Ordovician limestone failure surfaces. With increasing confining pressure, pore depth and crack formation connecting the pores also increase. Beyond the critical confining pressure, the mesoscopic roughness of the failure surface decreases, and the range of interval-distributed pore roughness diminishes. Additionally, we conducted a detailed investigation into the water conductivity properties of rocks under different stress states using Barton's joint roughness coefficient (JRC) index and rock fractal theory. The roughness features of rock failure surfaces were classified into three categories based on mesoscopic pore and crack undulation forms: straight, wavy, and jagged. We also observed significant confining pressure effects on limestone and sandstone, which exceeding the critical confining pressure led to increased water conductivity in both rocks, albeit through different mechanisms. While sandstone exhibits fissures running across it, limestone shows shear abrasion holes. Beyond the critical confining pressure, the rock failure surface becomes smoother, leading to decreased water flow blocking capacity. The fractal dimension of Ordovician limestone increases significantly under critical confining pressure, leading to a more complex mesoscopic crack extension route.

Biodegradation of Crude Oil by Nitrate-Reducing, Sulfate-Reducing, and Methanogenic Microbial Communities under High-Pressure Conditions.

Carbon capture, utilization, and storage (CCUS) is an important component in many national net-zero strategies, and ensuring that CO2 can be safely and economically stored in geological systems is critical. Recent discoveries have shown that microbial processes (e.g., methanogenesis) can modify fluid composition and fluid dynamics within the storage reservoir. Oil reservoirs are under high pressure, but the influence of pressure on the petroleum microbial community has been previously overlooked. To better understand microbial community dynamics in deep oil reservoirs, we designed an experiment to examine the effect of high pressure (12 megapascals [MPa], 60 °C) on nitrate-reducing, sulfate-reducing, and methanogenic enrichment cultures. Cultures were exposed to these conditions for 90 d and compared with a control exposed to atmospheric pressure (0.1 MPa, 60 °C). The degradation characteristic oil compounds were confirmed by thin-layer analysis of oil SARA (saturates, aromatics, resins, and asphaltenes) family component rods. We found that the asphaltene component in crude oil was biodegraded under high pressure, but the concentration of asphaltenes increased under atmospheric pressure. Gas chromatography analyses of saturates showed that short-chain saturates (C8-C12) were biodegraded under high and atmospheric pressure, especially in the methanogenic enrichment culture under high pressure (the ratio of change was -81%), resulting in an increased relative abundance of medium- and long-chain saturates. In the nitrate-reducing and sulfate-reducing enrichment cultures, long-chain saturates (C22-C32) were biodegraded in cultures exposed to high-pressure and anaerobic conditions, with a ratio of change of -8.0% and -2.3%, respectively. However, the relative proportion of long-chain saturates (C22-C32) increased under atmospheric pressure. Gas Chromatography Mass Spectrometry analyses of aromatics showed that several naphthalene series compounds (naphthalene, C1-naphthalene, and C2-naphthalene) were biodegraded in the sulfate-reducing enrichment under both atmospheric pressure and high pressure. Our study has discerned the linkages between the biodegradation characteristics of crude oil and pressures, which is important for the future application of bioenergy with CCUS (bio-CCUS).