Boundary Conditions Research Articles

Promoting proactive extra-role service behaviors through empowering leadership: the role of mindfulness

PurposeBased on conservation of resources theory, this study aims to understand how employees’ level of mindfulness serves as a boundary condition capable of negatively conditioning the process through which empowering leadership affects employees’ proactivity and extra-role service (ERS) behaviors.Design/methodology/approachA total of 361 Spanish frontline employees in the hospitality sector collaborated in this research. We tested our hypotheses using a bootstrapping method to perform a regression study employing the PROCESS macro developed for Statistical Package for Social Sciences (SPSS).FindingsAs expected, our results confirmed the direct and indirect positive effects between empowering leadership and ERS. However, these effects nearly disappeared when employees exhibited high levels of mindfulness.Originality/valueWorker ERS behavior is a key way for hotels to distinguish themselves from competitors. Paradoxically, ERS is discretionary and not part of the employee’s formal duties. Although mindfulness is often promoted to enhance organizational functioning, our study highlights its drawbacks in hospitality. Hotel work requires proactive decision-making, and we found that mindfulness curbs this, thereby impeding ERS. This study suggests that mindfulness may act as an anchor in a service work environment.

The Behavior of Elbow Elements at Pure Bending Applications Compared to Beam and Shell Element Models

Abstract This paper studies the response of ELBOW31 and ELBOW31B element types under pure bending conditions, using shell and beam element models for benchmarking. Various model lengths are evaluated, showing that a model length of six pipe diameters exhibits a hardening effect when total strain exceeds 3.5%, though a strain up to 1% is deemed sufficient for pipeline design. The study examines the effects of ovality modes and boundary conditions such as NOWARP and NOOVAL on the bending response. ELBOW31 with one or two ovality modes yields accurate results, while additional ovality modes or zero ovality mode can lead to overprediction of the elastic bending moment capacity. The introduction of the NOWARP condition enhances the accuracy of the ELBOW31 model, while the NOOVAL condition alone produces unrealistic results. The simplified ELBOW31B model shows good agreement with the ELBOW31-NOWARP model but similarly overpredicts the bending moment when zero ovality mode is used. The study also finds that Poisson's ratio and model length have no significant impact on the bending response when no restrictions are applied. Additional analyses, as presented in Appendices A and B, highlight the importance of D/t ratios in pipeline performance. A D/t ratio of 20 offers a stiffer response with reduced ovalization, while a D/t ratio of 50 results in greater flexibility and increased ovalization. These findings provide valuable insights for the selection of element types, boundary conditions, and D/t ratios in robust pipeline design.

Eigenvalue variations of the Neumann Laplace operator due to perturbed boundary conditions

This work considers the Neumann eigenvalue problem for the weighted Laplacian on a Riemannian manifold (M,g,∂M) under a singular perturbation. This perturbation involves the imposition of vanishing Dirichlet boundary conditions on a small portion of the boundary. We derive an asymptotic expansion of the perturbed eigenvalues as the Dirichlet part shrinks to a point x∗∈∂M in terms of the spectral parameters of the unperturbed system. This asymptotic expansion demonstrates the impact of the geometric properties of the manifold at a specific point x∗. Furthermore, it becomes evident that the shape of the Dirichlet region holds significance as it impacts the first terms of the asymptotic expansion. A crucial part of this work is the construction of the singularity structure of the restricted Neumann Green’s function which may be of independent interest. We employ a fusion of layer potential techniques and pseudo-differential operators during this work.

Analysis of the dynamic responses of a piezothermoelastic microbeam resonator under dual-phase-lag heat conduction

Thermoelastic vibration responses of a piezothermoelastic (PTE) microbeam resonator have been investigated in the present work under simply supported boundary conditions. The basic governing equations for a transversely isotropic piezothermoelastic solid are formulated by assuming the Euler–Bernoulli beam theory with hyperbolic dual-phase-lag (DPL) heat conduction model. Later on, non-dimensionalization of the variables have been carried out for simplicity to obtain the set of coupled governing equations for thermal deflection, electric field, and thermal moment. Initial and boundary conditions are defined to solve for the non-dimensional thermal deflection and thermal moment by using Laplace transform technique along with the finite Fourier sine transform. Closed-form solutions of the problem are obtained. Moreover, an attempt is made to illustrate the analytical results through numerical simulations by taking a PTE material of Lead Zirconate Titanate (PZT-5A). The influence of the quadratic term of the phase-lag parameter of heal flux in the DPL model is investigated to compare the effects of phase-lags under parabolic and hyperbolic DPL models. In addition, the long-term and short-term vibration responses of thermal moment and thermal deflection are analyzed in detail to observe the impact of different factors which characterize the piezoelectric phenomena and dual-phase-lag effects. Comparative analysis of different well-known models for responses of thermal moment and thermal deflection is also presented for short- and long-time ranges. Some important observations about how piezoelectric parameters, dual-phase-lag parameters, and beam parameters affect the behavior of piezothermoelastic vibrations have been highlighted.

Probing chiral-symmetric higher-order topological insulators with multipole winding number

The interplay between crystalline symmetry and band topology gives rise to unprecedented lower-dimensional boundary states in higher-order topological insulators (HOTIs). However, the measurement of the topological invariants of HOTIs remains a significant challenge. Here, we define a multipole winding number (MWN) for chiral-symmetric HOTIs by applying a corner twisted boundary condition. The MWN, arising from both bulk and boundary states, accurately captures the bulk-corner correspondence including boundary-obstructed topological phases. To address the measurement challenge, we leverage the perturbative nature of the corner twisted boundary condition and develop a real-space approach for determining the MWN in both two-dimensional and three-dimensional systems. The real-space formula provides an experimentally viable strategy for directly probing the topology of chiral-symmetric HOTIs through dynamical evolution. Our findings not only highlight the twisted boundary condition as a powerful tool for investigating HOTIs, but also establish a paradigm for exploring real-space formulas for the topological invariants of HOTIs.

An outliers-free isogeometric modeling method of rotating disk-shaft systems under elastic boundary conditions

An outliers-free isogeometric modeling method of rotating disk-shaft systems under elastic boundary conditions

Always on emails and employee wellbeing: the role of subjective norm of connectivity

PurposeIn recent years, technological advancement has radically changed the landscape of work by creating an “always-on” workplace. As a result, many employees use their information and communication technologies (ICTs) to perform work-related tasks during personal times. This constant availability then paves the way for harming the employee’s wellbeing. Nevertheless, research on ICTs usage after-hours has received limited consideration in organizational scholarship. To address this gap in the literature, current study aims to examine the relationships between workplace telepressure and employee wellbeing with the role of work-related email (WRE) use after-hours and subjective norm of connectivity.Design/methodology/approachData were collected from 421 employees from different sectors. The hypotheses were tested using structural equation modeling and PROCESS macro for SPSS.FindingsThe results showed that (1) workplace telepressure positively relates to work-related email use after-hours; (2) work-related email use after-hours negatively relates to employee wellbeing; (3) the subjective norm of connectivity moderates the link between workplace telepressure and work-related email use after-hours and (4) work-related email use during nonwork hours mediates the link between workplace telepressure and employee wellbeing.Originality/valueThis study contributes to overcoming the lack of studies by investigating underlying mechanisms and boundary conditions for ICTs during nonwork hours. In this expanded sense, this study broadens our understanding of WRE use after-hours by delineating the impact of workplace telepressure, subjective norm of connectivity and employee wellbeing.

Free vibration of nanobeams with surface and dynamic flexoelectric effects

In this paper, the free vibration of piezoelectric nanobeams considering static flexoelectric, dynamic flexoelectric, and surface effects is studied. Based on the theories of the Timoshenko beam and Euler-Bernoulli beam, a theoretical model of flexoelectric nanobeams is established and the governing equations and boundary conditions of this model are derived using the variational principle. Then, the analytical solution of the frequency equation is obtained by using the Navier method. Numerical results indicate that the size dependence of the dynamic flexoelectric effect is stronger than the surface effect. The surface and dynamic flexoelectric effects exhibit a competitive mechanism on the natural frequency.

The role of Dark Triad personality traits in consumers’ counterfeit luxury consumption: a moderated mediation model

PurposeThe purpose of this research is to examine the influence of the Dark Triad personality traits (Machiavellianism, narcissism and psychopathy) on consumers’ purchase intentions for counterfeit luxury products via the mediating effect of moral disengagement, drawing on moral disengagement theory. Furthermore, descriptive norms are tested as a moderators of the mediated relationships between the Dark Triad personality traits and purchase intentions via moral disengagement based on trait activation theory.Design/methodology/approachTo test the hypotheses, a survey design is employed to gather primary data from 205 consumers. The final data are analysed using partial least squares structural equation modelling.FindingsThis study finds that moral disengagement mediates the relationships between (1) Machiavellianism, (2) psychopathy and purchase intentions. Descriptive norms are found to moderate the indirect effect of moral disengagement between psychopathy and purchase intentions.Originality/valueDark Triad personality traits are linked to various unethical behaviours. However, no studies have explored how Dark Triad personality traits influence consumers’ purchase intentions for counterfeit luxury products. This study sheds light on how consumers with high Dark Triad personality traits are more likely to be morally disengaged, thereby leading to purchase intentions for counterfeit luxury products, drawing on moral disengagement theory. Furthermore, this study demonstrates descriptive norms as the boundary condition for the mediating relationship between Dark Triad personality traits and purchase intentions via moral disengagement, drawing on trait activation theory. The findings can be used to formulate better strategies to counteract the phenomenon of counterfeit luxury consumption.

Optical, magnetic, and transport properties of a quantum well heterostructure under the influence of boundary conditions

The magneto-optical transport (MOT) properties of a heterostructure Pöschl–Teller symmetric quantum well (PTSQW) under the effect of the boundary condition are studied. The phonon confinement models proposed by Knipp and Reinecke, Huang and Zhu, Fuchs and Kliewer, and Ridley and Babiker are considered in HgS and GaAs materials. The profile and operator projection approaches are utilized to compute the MOT properties, which include the full width at half maximum (FWHM) and the absorption power (AP). Our main result is depicted as follows: The FWHM values for the confining phonon absorption case are consistently greater than those for the confining phonon emission case in both HgS and GaAs. The FWHM values in HgS are consistently greater than those in GaAs for both the confining phonon emission and absorption cases. The MOT properties of HgS material are more dominant than those of the GaAs one when taking phonon confinement into account. The use of both electromagnetic and lattice dynamics boundary conditions (BC) simultaneously best describes the e–p interaction in PTSQW heterostructure. The electromagnetic BC is the most significant and cannot be disregarded in confined phonon models. The hydrodynamic BC is unsuitable for studying e–p interaction in QW heterostructure. In addition to the electromagnetic and lattice dynamics BCs, the additional use of the orthogonal BC of optical phonon modes for all values of k→ has only a modest effect on the description of the e–p interaction in QW heterostructure. Our findings agree well with the reported theoretical (Bhat et al., 1994) and experimental (Tatham et al., 1989; Seilmeier et al., 1987) pieces of evidence.

Constraining the inner boundaries of COCONUT through plasma beta and Alfvén speed

Space weather modelling has been gaining importance due to our increasing dependency on technology sensitive to space weather effects, such as satellite services, air traffic and power grids. Improving the reliability, accuracy and numerical performance of space weather modelling tools, including global coronal models, is essential to develop timely and accurate forecasts and to help partly mitigate the space weather threat. Global corona models, however, require accurate boundary conditions, for the formulations of which we have very limited observational data. Unsuitable boundary condition prescriptions may lead to inconsistent features in the solution flow field and spoil the code's accuracy and performance. In this paper, we develop an adjustment to the inner boundary condition of the COolfluid COrona uNstrUcTured (COCONUT) global corona model to better capture the dynamics over and around the regions of stronger magnetic fields by constraining the plasma beta and the Alfvén speed. Using data from solar observations and solar atmospheric modelling codes such as Bifrost, we find that the baseline homogeneous boundary condition formulations for pressure and density do not capture the plasma conditions physically accurately. We develop a method to adjust these prescribed pressure and density values by placing constraints on the plasma beta and the Alfvén speed that act as proxies. We demonstrate that we can remove inexplicable fast streams from the solution by constraining the maximum Alfvén speed and the minimum plasma beta on the boundary surface. We also show that the magnetic topology is not significantly affected by this treatment otherwise. The presented technique shows the potential to ease the modelling of solar maxima, especially removing inexplicable features while, at the same time, not significantly affecting the magnetic field topology around the affected regions.

A note on ideal Magneto-Hydrodynamics with perfectly conducting boundary conditions in the quarter space

We consider the initial–boundary value problem in the quarter space for the system of equations of ideal Magneto-Hydrodynamics for compressible fluids with perfectly conducting wall boundary conditions. On the two parts of the boundary the solution satisfies different boundary conditions, which make the problem an initial–boundary value problem with non-uniformly characteristic boundary.We identify a subspace H3(Ω) of the Sobolev space H3(Ω), obtained by addition of suitable boundary conditions on one portion of the boundary, such that for initial data in H3(Ω) there exists a solution in the same space H3(Ω), for all times in a small time interval. This yields the well-posedness of the problem combined with a persistence property of full H3-regularity, although in general we expect a loss of normal regularity near the boundary. Thanks to the special geometry of the quarter space the proof easily follows by the “reflection technique”.

Research on the impact of employee AI identity on employee proactive behavior in AI workplace

PurposeThe purpose of our research is to explore the role of employee AI identity in influencing employee proactive behavior and its boundary conditions in AI workplace.Design/methodology/approachBased on the IT identity theory and motivation theory, our research discusses the effects of employee AI identity on employee proactive behavior and regarded the proactive work intention as a mediating variable. Meanwhile, we considered organization inducement as a boundary condition and discussed the moderating effects of it and its two sub-dimensions (development rewards and material rewards). Data were collected from 326 employees and partial least squares structural equation modeling was used to analyzed and draw the conclusions.FindingsFindings showed that employee AI identity significantly affects employee proactive behavior, in which the proactive work intention play a mediating role. Moreover, three subdimensions (relatedness, emotional energy, dependence) of employee AI identity have different effects on formation of employee AI identity. And organization inducement acts as a positive moderating role, development rewards and material rewards play different roles in the formation of organization inducements.Originality/valueOur research explores the different paths that influence employee proactive behavior and their boundary moderation, while analyzing the results of these influences in different subdimensions, deepening the research on employee AI identity and organization inducement. Our research is conducive to the development of the identity theory and organizational behavior research and provide suggestions for managers to improve their organizational management level.

Economic Assessment of Maritime Fuel Transformation for GHG Reduction in the International Shipping Sector

This study aims to predict the economic transition pathway for alternative fuels in accordance with the 2023 IMO GHG Strategy goals. The assessment considers the impact of alternative fuel transition on fuel costs (∆COSTFuel,t), carbon emission costs (∆COSTCO2 eq,t), and ship new/retrofit costs (∆COSTship). The parameters and boundary conditions were set based on the current status and trends in the international shipping industry, as determined from previous research, to predict the economic transition pathway for alternative fuels. The results show that in 2050, with a standardized economic efficiency of 130%, profit will reach its maximum value, approximately −54,000 million USD. The study standardized fuel ΔCOSTj, normalized, and ΔNPV%j, normalized as a basis for adjusting penetration rates. At this time, considering fuel costs and NPV%, the composition of alternative fuels is as follows: bio-LNG, bio-Methanol, e-LNG, e-Methanol, e-Ammonia, BD, and Fossil-LNG, with shares of 18.56%, 4.00%, 25.64%, 6.00%, 10.00%, 28.00%, and 0%, respectively. Compared to conventional marine fuel HFO, the increase ranges from 23.54% to 69.50% in the 2030s, 0.52% to 0.55% in the 2040s, and decreases by 6.88%– 14.69% in 2050. Using more LNG and BD in the 2040s and 2050 is an alternative way to achieve a better economic fuel transition. Moreover, the economic penetration rate combination set in this study can achieve sufficiently small ∆COSTT,t and sufficiently large NPVΔt under specific assumptions and boundary conditions, rather than an absolute minimum ∆COSTT,t or the absolute maximum NPVΔt. The results revealed that no single alternative fuel has a comprehensive advantage in reducing carbon intensity and economic performance at all times. Given the uncertainties in the supply chain, cost-effectiveness, and infrastructure for Methanol and Ammonia, LNG and BD play a crucial role in the transition of international shipping fuels. Our work provides a fundamental and comprehensive prediction of fuel transition based on the current status and trends in the international shipping industry.

Linking leader boundary spanning to task performance and its boundary conditions: a conservation of resources perspective

PurposeDrawing on conservation of resources (COR) theory, this research aims to advance the current understanding of leader boundary spanning by examining its effect on task performance, psychological mechanism and boundary conditions.Design/methodology/approachThe empirical data were gathered by a paper-and-pencil survey from 155 employee-supervisor dyads working in various industries.FindingsOur results indicated that leader boundary spanning is positively related to task performance, mediated by employees’ enhanced self-efficacy. Moreover, the results indicated that the positive effect of leader boundary spanning on task performance via enhanced self-efficacy is strengthened when the level of abusive supervision is low or when the level of an employee’s emotional exhaustion is high.Practical implicationsOrganizations should find a way to facilitate leaders to engage in boundary spanning behaviors since a leader’s boundary spanning behavior enhances task performance through employee’s self-efficacy. Additionally, it is crucial to establish policies and provide training sessions to reduce the occurrence of abusive supervision in the workplace.Originality/valueThis study gives insights into the current literature by uncovering whether, how and under what circumstances boundary spanning leaders exert influences on task performance via employees’ self-efficacy. Our results showed that the positive effect of leader boundary spanning is likely to be strengthened when boundary spanners do not abuse their employees or when employees are in need of additional resources.

Experimental Study: Stress Path Coefficient in Unconsolidated Sands: Effects of Re-Pressurization and Depletion Hysteresis

Accurate estimation of in-situ stresses is a critical parameter for geo-mechanical modelling. In-situ stresses are estimated in the field from logs and frac tests. Laboratory tests are performed with cored material to estimate horizontal stress changes under defined boundary conditions to complement field data. Horizontal stress path coefficient is used to estimate a change in in-situ stresses as the reservoir undergoes depletion or injection. Uniaxial Strain boundary conditions are representative of far field stress state. The laboratory data provides the change in horizontal stress with a change in pore pressure. It is used to complement the field data acquisition of absolute stress values to predict the value of total stresses. This experimental study provides a novel method of simulating geological compaction for fabricating representative samples from unconsolidated sands. It investigates the variability of horizontal stress path coefficient as a function of changing pore pressure (depressurization and re-pressurization) in unconsolidated sandstone reservoirs. Synthetic sandstones samples were made from sand packs by consolidating them under an isostatic stress path at ambient pore pressure. After getting to initial reservoir conditions, a series of pore pressure depletion and injection tests with varying magnitudes (injection and depletion) were performed to study the effects of stress path direction and associated hysteresis. The magnitude of the stress path coefficient under depletion is lower than that under injection for the first load-unload cycle. In subsequent load-unload cycles, the stress path coefficient values remain constant until the sample is depleted to a new level of pore pressure. A Modified Cam Clay model is fit to the data to map the expansion of the yield surface and quantify the model parameters. Application of this research includes accurate prediction of changes in-situ stresses during depletion and injection stress paths for simulating unconsolidated reservoirs behavior under fluid injection or further depletion.

In-plane vibration analysis of elastically restrained FGM skew plates using variational differential quadrature method

This work presents an accurate in-plane vibration analysis of functionally graded material (FGM) skew plates with elastically restrained boundaries using the variational differential quadrature method (VDQM). The weak form of the governing equations is derived by integrating two-dimensional elasticity theory with Hamilton's principle. The differential and integral operators are directly converted into matrix forms, thereby removing the necessity for higher-order derivative approximations in the displacement field. Transformation matrices are then developed for both interior and boundary nodes to link the governing equations with the boundary conditions, leading to the formulation of the vibration eigenvalue equations for FGM skew plates. Various factors, including aspect ratios, skew angles, boundary restraints, and gradient indices, are considered to investigate the in-plane vibration mode characteristics of FGM skew plates. Detailed solution procedures are provided, and numerical examples using the proposed solutions indicate that the VDQM exhibits superior numerical convergence and stability compared to other existing methods. The study also investigates the influence of highly skewed plates (75°), where stress singularities arise at the corners. This aspect is crucial for in-plane vibration analysis and has garnered limited attention in the existing literature. Furthermore, the dynamic analysis of FGM skew plates reveals a coupling between normal and tangential vibration modes.

Industrial diversity, formal, and informal institutions: a configurational moderation of the innovation input-output relationship

ABSTRACT This study seeks to uncover configurations of industrial diversity and institutions that act as boundary conditions in the conversion of innovation inputs into outputs. Specifically, we analyse how industrial diversity, rule of law, open markets, power distance, and individualism combine to influence countries’ transformation of innovation inputs into innovation outputs. A novel, two-stage fuzzy-set qualitative comparative analysis is used to identify configurational moderation on panel data from 66 countries. Results revealed three distinct equifinal combinations of conditions that moderate the innovation input-output relationship: (1) the presence of open markets and individualism, coupled with the absence of power distance; (2) the presence of industrial diversity, open markets, and individualism; and (3) the presence of rule of law and power distance. These configurations support the presence of high innovation outputs, even when innovation inputs lose importance. This study reconciles the literature on industrial structure with institutional theory and embeds them in the NSI approach. Furthermore, it helps to clarify the current discussions of whether innovation benefits more from industrial diversity or specialisation, or through one cultural profile or another. Thus, the study sheds light on previous inconsistencies in the literature by harmonising different approaches to innovation.

CFD simulation of injection point design for emergency core cooling system of ALLEGRO

The Emergency Core Cooling System (ECCS) is one of the critical safety systems in the Gas-cooled Fast Reactor (GFR) demonstrator ALLEGRO. The ECCS design must be improved to enhance fundamental safety functions, particularly in removing heat from the core under postulated plant conditions. In this paper, we focused on exploring the effect of coolant injection point on the performance of ECCS, for more efficient core cooling under Loss Of Coolant Accident (LOCA) scenarios. We initially performed a 1D primary system loop thermal hydraulic simulation to determine appropriate boundary conditions in case of a LOCA. These conditions were then applied to a CFD model of the ALLEGRO reactor pressure vessel, including injection nozzles at two positions. Transient 3D CFD simulations of LOCA in ALLEGRO were carried out using Fluent to determine location of the most effective emergency coolant injection point. We simulated the flow distribution through the core up to around 30 s after both small- and large-break LOCA events. The results suggest that bottom injection of the emergency coolant is preferred in an updated ECCS design. It provides a more uniform flow distribution across the core and therefore more advantageous than the previously suggested location in the downcomer.

Dynamics of Poisson-Boltzmann equations: “Hidden” mechanisms for Gouy-Chapman layer and beyond

In this work a dynamical system approach is taken to systematically investigate the one-dimensional classical Poisson-Boltzmann (PB) equation with various boundary conditions. This framework has a unique advantage of a geometric view of the dynamical systems, which allows one to reveal and examine critical features of the PB models. More specifically, we are able to reveal the mechanism of Gouy-Chapman layer: the presence of an equilibrium for the PB equation, including equilibrium-at-infinity for Gouy-Chapman's original setup as the limiting case. Several other critical, somehow counterintuitive, features revealed in this work are the saturation phenomenon of surface charge density, the uniform boundedness of electric pressure (given length) and of length (given electric pressure) in surface charge, and the critical length for a reversal of electric force direction. All have a common mechanism: the presence of an equilibrium for the PB equation. We believe that the critical features presented from the classical PB models persist for modified PB systems up to a certain degree.By all means, these findings are by chance which is probably why the mechanism has been missing after the phenomenon of Gouy-Chapmann layer and alike had been discovered for very long. Only when viewed from the nonlinear dynamical systems theory, these results become rather apparent.