Cyclic Model Research Articles

Performance assessment of phase change material-based thermal energy storage

Phase change material (PCM) based thermal energy storage (TES) offers high energy density and better heat transfer performance by encapsulating PCM within a specifically designed container, i.e., shell and tube type TES. In this work, the PCM is packed in multiple cylindrical tubes, and heat transfer fluid (HTF) flows in the annulus. Such arrangement of PCM and HTF in the TES system is termed a cylindrical model, and the one opposite to the cylindrical model is called a pipe model. This work conducts the performance evaluation for PCM-based shell and tube TES using an experimentally validated numerical model. The 3D cyclic periodic model for TES has been developed based on hexagonal circle packing, and the effective energy storage ratio as a performance index under varying geometrical and operating parameters has been investigated. The variation in parameters includes tube length (0.5–7 m), diameter (10–50 mm), initial temperature (293.15–303.15 K), volumetric flow rate (10–500 l/min), inlet temperature (323.15–393.15 K). Using a conjugate heat transfer model, the influence of parameters was investigated, and the performance index was evaluated using the effectiveness-NTU theory. It was found that TES was effective for geometrical parameters diameter d≤ 30 mm and length L≥ 2 m. The performance index of 1.54 was optimum and achieved when the inlet temperature was 333.15 K. This optimum performance index value was compared with existing work and found to be performing comparatively well.

Hysteretic behavior and cyclic constitutive model of corroded low-alloy steel in a corrosive environment

To quantitatively analyze the mechanical properties of corroded low-alloy steel under monotonic and cyclic loading, a cyclic constitutive model was established. Accelerated corrosion, monotonic tensile testing, and cyclic loading testing of 28 groups of Q345B steel specimens were conducted to examine how corrosion affected the monotonic tensile and hysteresis characteristics of the specimens, and the combined hardening parameters based on the Chaboche model were calibrated and confirmed based on the test findings. The results showed that corrosion clearly affected the monotonic stress-strain curve of steel and that most mechanical indices deteriorated linearly with respect to the corrosion rate. The combination of corrosion and cyclic cumulative damage exacerbated the degradation of the deformation capacity of the steel and affected its energy consumption capacity and cyclic hardening. The constitutive model of corroded steel calibrated on the basis of cyclic loading test data could effectively simulate the hysteresis performance of corroded Q345B steel under cyclic loading.

Cyclic behaviour modelling of additively manufactured Ti-6Al-4V lattice structures

The present work is concerned with the numerical modelling of the cyclic behaviour of Ti-6Al-4V lattice structures. In the study, diamond structures of titanium alloy produced by the additive laser powder bed fusion (LPBF) method with different degrees of relative density were used. Realistic geometric models of the studied mesostructures were generated using computed microtomography, taking into account the imperfections of the material resulting from the manufacturing process. The numerical calculations also took into account the actual material hardening curve in the elastic-plastic strain range. One of the achievements of this work is the numerical modelling of cyclic loading of realistic mesostructures with their imperfections. The areas of the mesostructures most susceptible to fatigue cracking have been identified and analysed. True hysteresis loops and values of local stress and strain amplitude were determined at the locations of highest stress concentration in cyclically loaded diamond structures. The main achievement of the present work was the modelling of the macroscopic fatigue life of the investigated mesostructures based on the true values of stress and strain at the locations most exposed to fatigue cracking. For this purpose, a stress criterion for fatigue cracking of Ti-6Al-4V lattice structures fabricated by the additive LPBF method was proposed.

Degradation of Seismic Performance of Thin Steel Plate Shear Walls in Earthquakes

Steel plate shear walls (SPSWs) are widely used in earthquake-prone areas, and they usually undergo multiple earthquakes throughout their service lives. The performances of SPSWs under a single shot of an earthquake have been widely studied, although the secondary seismic performance of earthquake-damaged structures remains unclear. Damage to an SPSW structure during an earthquake is difficult to evaluate. In this study, the degradation of the seismic performance of SPSWs during earthquakes was investigated. A test specimen was subjected to a two-stage quasistatic load. The plastic development and failure modes of SPSW specimens were investigated. The degradation of bearing capacity, stiffness, and energy dissipation performance was analyzed. On the basis of the experimental investigation, finite-element models introducing the ductile damage criterion and the cyclic constitutive model of steel were established. The degradation of the seismic performance of SPSWs under secondary earthquakes was studied. The results indicate that the stiffness of the SPSWs degrades more significantly than the bearing capacity. The larger the height-to-thickness ratio of the embedded plate, the more obvious the decrease in the bearing capacity, and the smaller the decrease in stiffness. With the increase in the maximum lateral displacement reached by the structure in an earthquake, and as the pinch phenomenon of the hysteresis curve of the SPSW becomes more serious, the energy dissipation capacity shows a uniform downward trend.

Language teacher professional curiosity: Understanding the drive for professional development

Teacher professional development (PD) has been shown to have numerous benefits, such as greater self-efficacy, higher motivation, and enhanced wellbeing (e.g., Kimura, 2014; Polin, 2023; Wang & Chen, 2022), and teaching additional languages is certainly no exception. However, the extent to which teachers are willing and able to engage in PD throughout their careers depends on many factors, some of which are related to the context in which they work, while others are reflective of their individual attributes such as attitudes, motivations, and personality. This paper focuses on the latter by reporting the findings of a study that examined language teacher professional curiosity (LTPC). The data were collected through semi-structured interviews from 6 Austrian and 6 Polish language teachers at different stages of their careers. Qualitative analysis allowed valuable insights into the nature of LTPC, curiosity-driven behaviors as well as factors influencing these behaviors. It also provided the basis for a tentative cyclic process model of LTPC in which interest and curiosity interact to produce a focus of curiosity, which is impacted by motivation, agency, autonomy, and social context, generating a drive for teacher behaviors in respect to their PD.

Fixed-income average options: a pricing approach based on Gaussian mean-reverting cyclical models

This paper values fixed-income (discrete- and continuous-time) European Asian and Australian options. We assume that the term structure of interest rates is modelled by the specification proposed in Moreno et al. (Econ Model 72:140–150, 2018, https://doi.org/10.1016/j.econmod.2018.01.015). We obtain closed-form expressions for the premiums of geometric average options and, for arithmetic average options, premiums are computed by numerical methods. We also perform a sensitivity analysis with respect to different parameters for both (geometric and arithmetic) options.

Refocusing on the start and end of tourists’ decision-making: Measuring thresholds and information loop limits

In this era of abundant travel-related information, tourist decision-making processes have become increasingly complex and nonrational. This study focuses on the initiation and conclusion instances of decision-making between the pre-decision, decision-in-progress, and post-decision phases to capture the diversity of decisional behaviors. Building upon the Cyclic Model of Tourist Decision-Making, two new constructs, the Decision-Making Threshold (DMT) and Information Loop Limit (ILL), were validated with measurement tools developed, with which we empirically recognized the individual differences in the propensity to start and end decisions. Moreover, the dimensions of each construct were confirmed by incorporating the DMT for internal and external stimuli and the ILL based on cognitive capacity and willingness. The validation of the original theoretical concepts provides a basis for future research, including the examination of correlations among DMT, ILL, and other consumption-related behaviors. Four distinct decision-making segments are identified and practical implications are discussed.

Decision-Making Conflict Measurement of Old Neighborhoods Renovation Based on Mixed Integer Programming DEA-Discriminant Analysis (MIP DEA–DA) Models

Renovating old neighborhoods for the benefit of people has become increasingly important in urban renewal. Nevertheless, old neighborhood renovations are currently considered a group decision-making issue under public participation, involving diverse decision-making subjects. Conflicts within a group are a common problem during group decision-making. In this paper, conflict is examined in the decision-making process for renovating old neighborhoods and novel ideas are provided for quantifying conflict. Public participation in old neighborhood renovations is assessed using conflict degree calculations in group decision-making. Based on the preferences of decision-making experts, a MIP DEA–DA (Mixed Integer Programming Data Envelopment Analysis–Discriminant Analysis) based partial binary tree cyclic clustering model is constructed for clustering experts, and an aggregated group conflict indicator and an aggregated conflict vector are computed, allowing for the quantification of conflict during the renovation process of the old neighborhood based on actual situations. Results indicate that there is primarily a conflict between the benefits of decision-making subject interests and the professionalism of decision-making renovations. This paper contributes to improving public participation, promoting the application of group decision-making theory in old neighborhood renovation, reducing conflict between decision-makers, and speeding up urban renewal.

Geodesically complete cyclic cosmologies and entropy

We demonstrate that there exists a class of cyclic cosmological models, such that these models can in principle solve the problem of the entropy growth, and are at the same time geodesically complete. We thus show that some recently stated conclusions, according to which cyclic cosmologies solving the problem of entropy growth can not be geodesically complete due to the Borde–Guth–Vilenkin (BGV) theorem, are not justified. We also add a short conceptual discussion on entropy and cyclic cosmology, and present a detailed analysis of entropy density growth during periodic and non-periodic evolution for cyclic cosmologies.

Cyclic Behavior and Stress-Strain Model of Nano-SiO2-Modified Recycled Aggregate Concrete.

Recycled aggregate concrete (RAC) possesses different mechanical properties than ordinary concrete because of inherent faults in recycled aggregates (RAs), such as the old interfacial transition zone (ITZ). However, the application of nano-SiO2 presents an effective methodology to enhance the quality of RA. In this study, nano-SiO2-modified recycled aggregate (SRA) was used to replace natural aggregate (NA), and the stress-strain relationships and cyclic behavior of nano-SiO2-modified recycled aggregate concrete (SRAC) with different SRA replacement rates were investigated. After evaluating the skeleton curve of SRAC specimens, the existing constitutive models were compared. Additionally, the study also proposed a stress-strain model designed to predict the mechanical behavior of concrete in relation to the SRA replacement rate. The results show that compared with RAC, the axial compressive strength of SRAC specimens showed increases of 40.27%, 29.21%, 26.55%, 16.37%, and 8.41% at specific SRA replacement rates of 0%, 30%, 50%, 70%, and 100%, respectively. Moreover, the study found that the Guo model's calculated results can accurately predict the skeleton curves of SRAC specimens.

Combined anisotropic and cyclic constitutive model for laser powder bed fusion fabricated aluminum alloy

This study presents new methods to effectively model the anisotropic yielding and hardening behavior of laser powder bed fusion fabricated aluminum alloy under both monotonic and cyclic loading conditions. The proposed model combines the yield surface-interpolation method to accurately describe the anisotropic hardening rates in various directions, with the Chaboche kinematic hardening rule to precisely reflect the cyclic characteristics. For numerical implementation of the combined anisotropic and cyclic constitutive model, a fully implicit stress integration algorithm based on return mapping method is provided. Moreover, the multiple parameters associated with the model are categorized and identified in an uncoupled manner. The isotropic and cyclic hardening parameters are determined by an inverse method, and the stability of the optimization outcomes is validated by applying different starting points for the parameters. Particularly, the back-stress effect on the identification of anisotropic parameters associated with the stress invariant-based Hill48 yield function is considered for the first time. This consideration leads to an improved prediction accuracy compared to the identification of anisotropic parameters without considering back-stress effect. The combined anisotropic and cyclic constitutive model, along with the calibrated parameters, are proven capable of accurately reproducing the intricate deformation behavior of laser powder bed fusion fabricated AlSi10Mg.

“I notice I'm getting more involved, interested, and excited about my future topic.” Action research as a transition from research steps to navigating graduate students' scholarly dispositions

Graduate students often approach research with predefined steps emphasising procedural aspects that occasionally expose their inadequate preparation for research as social practice. The purpose of this paper is to show how an action research (AR) methodology, in conjunction with English for Specific Purposes (ESP) and Systemic Functional Linguistics (SFL), has facilitated the scaffolding of explicit formal, rhetorical, procedural, and strategic knowledge in research discourse. We followed a cyclical action research model consisting of 1) recognising students' limited understanding of research as a social practice, 2) developing interventions to promote understanding of how language is structured, represented, and negotiated in scientific discourse, 3) results of the intervention, and 4) reflection. Thematic analysis of six participants' data, including their tasks, reflections, and draft proposals, revealed a discernible progression towards scholarly thinking, transformative learning, and the embodiment of scholarly identity. Integrating ESP and SFL frameworks enhanced our ability to guide students through research-specific discourses, moving beyond a purely theoretical understanding to engage in authentic practices. This approach contributed to the cultivation of Communities of Practice (CoP) in which student-faculty collaboration fostered a shared scholarly mindset and facilitated the gradual integration of students into these academic communities.

Time-dependent fatigue reliability analysis of heavy-haul railway steel bridges

Fatigue of heavy-haul railway bridges has been an ongoing concern due to the excessive stresses and frequent cyclic effects of freight trains. Current fracture-based fatigue research, which promotes fatigue reliability analysis caused by crack propagation, is challenged by the dilemma between the detailed modeling of cyclic stress and the reflection of temporal characteristics of loading conditions. In addition, due to the strong non-Gaussian nature of the fatigue limit state function and the computational inefficiency of integrating finite element analysis, current time-dependent reliability methods need to be further developed. To evaluate the fatigue reliability of heavy-haul railway steel bridges considering the temporal dependence of cyclic train loading, a time-dependent fatigue reliability methodology is developed in this study with two innovations. Firstly, a cyclic stress range model is proposed based on the load analysis at the bridge level, which can capture the time-dependent characteristics of the incurred stress range throughout service life. Then, an improved outcrossing rate method for strong non-Gaussian fatigue limit state functions is developed to reduce the computational costs associated with reliability analysis integrated with the finite element model. The developed time-dependent fatigue reliability methodology is then applied to a heavy-haul railway steel truss bridge located in Shandong, China, which proves its efficiency and accuracy in evaluating the time-dependent fatigue reliability of heavy-haul railway steel bridges. Furthermore, the developed methodology is able to provide insight into the balance between bridge fatigue damage and freight volume, and it is found that the combination of small train axle weight and high operation frequency is the optimal solution to achieve the fatigue reliability of the steel bridge while fulfilling the freight demand.

3D rolling contact finite element analysis of high-speed railway turnout considering ratchetting effect

The present work introduces a three-dimensional finite element model for the wheel-turnout-sleeper system, incorporating a cyclic constitutive model that accurately captures the nonlinear hardening behavior of rail steel under cyclic loadings. At the same time, a mixed implicit-explicit finite element method is employed to investigate the transient rolling contact behavior of wheel-turnout. Through dynamic analysis, the transient rolling contact status of the wheel-turnout, stress and strain responses of the turnout, and wheel-rail forces are investigated under varying crossing speeds and number of cycles. It is found that during the wheelset crossing, the contact stress remains relatively stable on the stock rail, and multi-point contact occurs at the wing rail and long point rail, and the contact stress on the surface of the long point rail is more significant. With an increase in crossing speed in the same cycle, there is a gradual rise in contact stress on the long point rail face. At the same crossing speed, with the increase in the number of cycles, the contact position between the wheelset and the long point rail gradually moves back, and the top width of the contact position gradually expands. Meanwhile, the fluctuation range of vertical displacement of the wheel center diminishes, and the wheel flange moves away from the long point rail. Additionally, a progressive accumulation of ratcheting strain is observed on the rail, and the ratcheting strain on the long point rail significantly exceeds that on the stock rail. The research results will help to provide a reference for the optimization and design of the critical cross-section profile of the long point rail and will have guiding significance for the maintenance and repair of turnouts.

Mobility restrictions in response to local epidemic outbreaks in rock-paper-scissors models

We study a three-species cyclic model whose organisms are vulnerable to contamination with an infectious disease which propagates person-to-person. We consider that individuals of one species perform a self-preservation strategy by reducing the mobility rate to minimise infection risk whenever an epidemic outbreak reaches the neighbourhood. Running stochastic simulations, we quantify the changes in spatial patterns induced by unevenness in the cyclic game introduced by the mobility restriction strategy of organisms of one out of the species. Our findings show that variations in disease virulence impact the benefits of dispersal limitation reaction, with the relative reduction of the organisms’ infection risk accentuating in surges of less contagious or deadlier diseases. The effectiveness of the mobility restriction tactic depends on the deceleration level and the fraction of infected neighbours which is considered too dangerous, thus triggering the defensive strategy. If each organism promptly reacts to the arrival of the first viral vectors in its surroundings with strict mobility reduction, contamination risk decreases significantly. Our conclusions may help biologists understand the impact of defensive strategies in ecosystems during an epidemic.

Occupational health risk assessment of PC production-caused pollution based on damage assessment and cyclic mitigation model

PurposeThe occupational health risk associated with the production of prefabricated concrete components is often overlooked. This paper will use a damage assessment and cyclic mitigation (DACM) model to provide individualized exposure risk assessment and corresponding mitigation management measures for workers who are being exposed.Design/methodology/approachThe DACM model is proposed based on the concept of life cycle assessment (LCA). The model uses Monte-Carlo simulation for uncertainty risk assessment, followed by quantitative damage assessment using disability-adjusted life year (DALY). Lastly, sensitivity analysis is used to identify the parameters with the greatest impact on health risks.FindingsThe results show that the dust concentration is centered around the mean, and the fitting results are close to normal distribution, so the mean value can be used to carry out the calculation of risk. However, calculations using the DACM model revealed that there are still some work areas at risk. DALY damage is most severe in concrete production area. Meanwhile, the inhalation rate (IR), exposure duration (ED), exposure frequency (EF) and average exposure time (AT) showed greater impacts based on the sensitivity analysis.Originality/valueBased on the comparison, the DACM model can determine that the potential occupational health risk of prefabricated concrete component (PC) factory and the risk is less than that of on-site construction. It synthesizes field research and simulation to form the entire assessment process into a case-base system with the depth of the cycle, which allows the model to be continuously adjusted to reduce the occupational health damage caused by production pollution exposure.

Participating in God’s redemptive work: A cyclical model for learning and assessment

With the goal of working towards decolonizing educational practices, this article considers the Indigenous medicine wheel as inspiration for a cyclical model for learning and assessment. Many current assessment practices highlight individual achievement rather than ongoing and relational learning. This article suggests using a Learning Wheel as a tool to engage students in conversation about learning and assessment. The purpose of assessment would be to inform students’ learning. The goal of learning would in turn equip students to be mindful of learning that engages in real-world issues to partner in God’s redemptive work.

Intravenous Reelin rescues despair-like behavior, Reelin cells in the dentate sub-granular zone, and spleen atrophy in the cyclic corticosterone model of recurring depressive episodes.

Novel antidepressants are predominantly evaluated preclinically in rodent models of chronic stress in which animals experience a single prolonged exposure to chronic stress prior to treatment. Rodent models of a single episode of chronic stress translate poorly to human depressive disorders, which are commonly marked by recurring depressive episodes. Intravenous administration of Reelin has previously been shown to resolve immobility in the forced swim test of rats exposed to a single prolonged exposure to chronic stress. To determine whether Reelin has antidepressant-like properties in a model of recurring depressive episodes, Long-Evans rats (N = 57) were exposed to multiple cycles of chronic stress and stress-free periods before the administration of a single injection of Reelin during the final cycle of chronic stress. The animals then performed in the forced swim test and open field test before the post-mortem evaluation of Reelin cell counts in the sub-granular zone of the dentate gyrus to determine the impact of treatment on hippocampal Reelin levels and spleen white pulp to evaluate the role of Reelin treatment in peripheral inflammation. The results show a single Reelin injection reversed elevated levels of immobility in the forced swim test in both male and female subjects exposed to the cyclic chronic stress model of recurring depressive episodes. Treatment with Reelin also restored Reelin-positive cell counts in the dentate gyrus sub-granular zone and reversed atrophy of spleen white pulp. The results shown here indicate that treatment with Reelin could effectively resolve alterations in forced swim test behavior caused by the cyclic corticosterone model of recurring depressive episodes and that Reelin homeostasis is important for regulating stress-related inflammation. Future preclinical antidepressant research should incorporate models of multiple depressive episodes to improve the translation of preclinical rodent research to human depressive disorders.

Attachment anxiety in daily experiences of romantic relationships: An expansion of the mutual cyclical growth model

This research provides a conceptual replication and theoretical extension of the mutual cyclical growth model. This model proposes that dependence promotes relationship commitment, which promotes pro-relationship behavior, which—when detected by partners—promotes partners’ trust, which promotes partners’ willingness to depend on the relationship. Prior research supports these links on a month-to-month basis, but romantic partners’ thoughts, feelings, and behaviors may change on a day-to-day basis. The present research sought to replicate the model on a daily level, and to extend the model with an important potential moderator: individuals’ attachment orientations. Results from a dyadic daily-report study of romantic couples replicated the links in the mutual cyclical growth model at the level of day-to-day fluctuations in partners’ experiences; the links were especially strong for individuals high in attachment anxiety. This research provides insight into mechanisms through which close relationships develop and strengthen.

Influence of corrosion on ultra-low cycle fatigue performance of steel butt-welded joints with various welding methods

Preferential corrosion of welded joints in steel structures has been observed in a wide range of scenarios and should receive enough attention. The current work focuses on the corrosion and ultra-low cycle fatigue (ULCF) behavior of low-alloy steel weld joints. Firstly, 1600 h neutral salt spray (NSS) tests were conducted on welded joints made by different welding methods, and then topography scanning of corrosion pits was carried out. It was found that the welded region is more susceptible to corrosion. Dynamic polarization curves of the welded joints were measured, and the results show that the self-corrosion potential of the welded region is lower than that of the base metal (BM) region, while the corrosion current density is higher than that of the BM region. Subsequently, cyclic tests were carried out on the corroded weld joints. The results show that corrosion can cause a maximum reduction of 11.79% in yield load and 20.87% in ultimate load of the welded joints. Corrosion has slight influence on the energy dissipation capacity of welded joints, but the maximum reductions in ULCF life could reach 77.31% due to corrosion. Fractography analysis further shows that secondary cracks, map cracks, and intergranular brittle fracture, apart from more common fatigue fracture, ductile fracture, and quasi-cleavage fracture, appear on the fracture surfaces. Supplementary numerical simulation was conducted to enable a better understanding of the failure processes. In the simulation, a geometric modeling method using topography scanning data of corrosion surface was proposed. By using the proposed modeling approach, together with Chaboche cyclic plasticity constitutive model and cyclic void growth model (CVGM) for capturing fracture behavior, the predicted results show an acceptable agreement with the experimental ones.