Search results

This study aims to propose a semiempirical and semitheoretical cyclic compaction constitutive model of coarse-grained soil filler for the high-speed railway (HSR) subgrade under cyclic load.

According to the basic framework of critical state soil mechanics and in view of the characteristics of the coarse-grained soil filler for the HSR subgrade to bear the train vibration load repeatedly for a long time, the hyperbolic empirical relationship between particle breakage and plastic work was derived. Considering the influence of cyclic vibration time and stress ratio, the particle breakage correction function of coarse-grained soil filler for the HSR subgrade under cyclic load was proposed. According to the classical theory of plastic mechanics, the shearing dilatation equation of the coarse-grained soil filler for the HSR subgrade considering particle breakage was modified and obtained. A semiempirical and semitheoretical cyclic compaction constitutive model of coarse-grained soil filler for the HSR subgrade under cyclic load was further established. The backward Euler method was used to discretize the constitutive equation, build a numerical algorithm of “elastic prediction and plastic modification” and make a secondary development of the program to solve the cyclic compaction model.

Through the comparison with the result of laboratory triaxial test under the cyclic loading of coarse-grained soil filler for the HSR subgrade, the accuracy and applicability of the cyclic compaction model were verified. Results show that the model can accurately predict the cumulative deformation characteristics of coarse-grained soil filler for the HSR subgrade under the train vibration loading repeatedly for a long time. It considers the effects of particle breakage and stress ratio, which can be used to calculate and analyze the stress and deformation evolution law of the subgrade structure for HSR.

The research can provide a simple and practical method for calculating deformation of railway under cyclic loading.

This study aims to research the large cross-section tunnel stability evaluation method corrected after considering the thickness-span ratio.

First, taking the Liuyuan Tunnel of Huanggang-Huangmei High-Speed Railway as an example and taking deflection of the third principal stress of the surrounding rock at a vault after tunnel excavation as the criterion, the critical buried depth of the large section tunnel was determined. Then, the strength reduction method was employed to calculate the tunnel safety factor under different rock classes and thickness-span ratios, and mathematical statistics was conducted to identify the relationships of the tunnel safety factor with the thickness-span ratio and the basic quality (BQ) index of the rock for different rock classes. Finally, the influences of thickness-span ratio, groundwater, initial stress of rock and structural attitude factors were considered to obtain the corrected BQ, based on which the stability of a large cross-section tunnel with a depth of more than 100 m during mechanized operation was analyzed. This evaluation method was then applied to Liuyuan Tunnel and Cimushan No. 2 Tunnel of Chongqing Urban Expressway for verification.

This study shows that under different rock classes, the tunnel safety factor is a strict power function of the thickness-span ratio, while a linear function of the BQ to some extent. It is more suitable to use the corrected BQ as a quantitative index to evaluate tunnel stability according to the actual conditions of the site.

The existing industry standards do not consider the influence of buried depth and span in the evaluation of tunnel stability. The stability evaluation method of large section tunnel considering the correction of overburden span ratio proposed in this paper achieves higher accuracy for the stability evaluation of surrounding rock in a full or large-section mechanized excavation of double line high-speed railway tunnels.

Posttraumatic stress disorder (PTSD), an anxiety disorder with lifetime prevalence of 7.8%, is characterized by symptoms that develop following exposure to traumatic life events and that cause an immediate experience of intense fear, helplessness or horror. PTSD is marked by recurrent nightmares typified by the recall of intrusive experiences and by extended disturbance throughout sleep. Individuals with PTSD respond poorly to drug treatments for insomnia. The disadvantages of drug treatment for insomnia underline the importance of non-pharmacological alternatives. Thus, the present study had three aims: first, to compare the efficiency of two relaxation techniques (muscular relaxation and progressive music relaxation) in alleviating insomnia among individuals with PTSD using both objective and subjective measures of sleep quality; second, to examine whether these two techniques have different effects on psychological indicators of PTSD, such as depression and anxiety; and finally, to examine how initial PTSD symptom severity and baseline emotional measures are related to the efficiency of these two relaxation methods. Thirteen PTSD patients with no other major psychiatric or neurological disorders participated in the study. The study comprised one seven-day running-in, no-treatment period, followed by two seven-day experimental periods. The treatments constituted either music relaxation or muscle relaxation techniques at desired bedtime. These treatments were randomly assigned. During each of these three experimental periods, subjects' sleep was continuously monitored with a wrist actigraph (Ambulatory Monitoring, Inc.), and subjects were asked to fill out several questionnaires concerned with a wide spectrum of issues, such as sleep, depression, and anxiety. Analyses revealed a significant increase in objective and subjective sleep efficiency and a significant reduction in depression level following music relaxation. Moreover, following music relaxation, a highly significant negative correlation was found between improvement in objective sleep efficiency and reduction in depression scale. The study‘s findings provide evidence that music relaxation at bedtime can be used as treatment for insomnia among individuals with PTSD.

Contemporary workplaces undergo frequent reorganizations in order to stay competitive in a working life characterized by globalization, digitalization, economic uncertainty, and ever-increased complexity. Managers are in the frontline of these challenges, leading themselves, organizations and their employees in high stress environments. This raises questions on how to support managers’ work-life sustainability, which is crucial for organizational sustainability. Mindfulness has been related to enhanced capacities to cope with challenges that are associated with organizational change. The authors evaluated short- and long-term effects of an eight-week mindfulness-based intervention in a company setting, which was going through reorganization.

Forty managers (42.5% males), mean age 54.53 (SD 5.13), were randomized to the mindfulness intervention or a non-active wait-list control. Self-report data were provided on individual sustainability factors in a work context: job demands and resources, psychological detachment, i.e. possibilities for letting go of work-related thoughts during leisure, control over work-nonwork boundaries, work-life balance, and mindfulness at baseline, postintervention, and at 6-month follow-up.

Linear mixed models (LMMs) analysis (all ps < 0.005 to 0.05) showed that the intervention group had a larger decrease in job demands and a smaller decrease in job resources, a larger increase in psychological detachment, work-nonwork boundary control, work-life balance, and mindfulness from baseline to postintervention when compared with the reference group. These initial effects were sustained at 6-month follow-up.

The study provides evidence that mindfulness practice can enhance managers’ long-term capacity to cope with challenging working conditions, and increase their work-life sustainability in times of organizational change and disruption.

This study aims to reduce the redundant weight of the anti-roll torsion bar brought by the traditional empirical design and improving its strength and stiffness.

Based on the finite element approach coupled with the improved beluga whale optimization (IBWO) algorithm, a collaborative optimization method is suggested to optimize the design of the anti-roll torsion bar structure and weight. The dimensions and material properties of the torsion bar were defined as random variables, and the torsion bar's mass and strength were investigated using finite elements. Then, chaotic mapping and differential evolution (DE) operators are introduced to improve the beluga whale optimization (BWO) algorithm and run case studies.

The findings demonstrate that the IBWO has superior solution set distribution uniformity, convergence speed, solution correctness and stability than the BWO. The IBWO algorithm is used to optimize the anti-roll torsion bar design. The error between the optimization and finite element simulation results was less than 1%. The weight of the optimized anti-roll torsion bar was lessened by 4%, the maximum stress was reduced by 35% and the stiffness was increased by 1.9%.

The study provides a methodological reference for the simulation optimization process of the lateral anti-roll torsion bar.

The purpose of this study is to identify the perception of workers before, during and after the implementation of changes derived from the lean manufacturing (LM) technique called value stream mapping (VSM) analysis and the causes that lead to this perception.

A qualitative methodological research design was adopted, using individual transcribed and coded interviews as the primary method of data collection.

At the beginning of the VSM changes, this study found strong denial and resistance emotional responses from workers due to the uncertainty and stress generated. The main cause of this resistance was their lack of understanding of the VSM analysis process presenting technical concepts, due to their educational level and the lack of a pre-existing organisational culture oriented toward continuous improvement. However, in the last stage of change, it is found that the workers accepted the new improvement proposals without resignation, improving their productivity and work performance because they saw and understood the improvements as effective.

This study will enable those responsible for organisations to anticipate the negative reactions that may arise from the organisational changes stemming from the implementation of VSM improvements. In addition, it adds new knowledge bases to the literature on the emotional consequences for employees during LM changes through VSM.

This study provides a qualitative analysis of the perceived emotional impact on workers that participated in LM techniques, in this case, focused on VSM analysis. It is an exploratory study that serves as a foundation for future research in the quantitative field.

Current approaches to sustainability science and education focus on (assessing and addressing) the external world of ecosystems, wider socio-economic structures, technology and governance dynamics. A major shortcoming of such approaches is the neglect of inner dimensions and capacities (which constrains education for sustainability as an end), and a limited capacity to facilitate reflection on the cognitive and socio-emotional processes underpinning people’s learning, everyday life choices and decision-taking (which constrains education for sustainability as a means). More integral approaches and pedagogies are urgently needed. The purpose of this paper is to advance related knowledge.

This paper provides a reflexive case study of the development of an innovative course on “Sustainability and Inner Transformation” and associated interventions in the form of a practice lab and weekly councils.

The paper elaborates on the connections between sustainability and inner transformation in education, offers insights into the process of adapting contemplative interventions to sustainability education and concludes with some reflections on challenges, lessons learnt and future work needed to support more integral approaches. The findings show that inner dimensions and transformation can be a vehicle for critical, improved education for sustainability and how this can be achieved in practice.

It is only recently that the concept of the inner or personal (sphere of) transformation has received growing attention in sustainability science and education. Despite this interest, such new conceptualizations and heuristics have, to date, not been systematically connected to education for sustainability (neither as an end nor means). The paper presents a critical, reflexive case, which advances related knowledge. It sets a precedent, which other universities/training institutions could follow or learn from.

This method will become a new development trend in subgrade structure design for high speed railways.

This paper summarizes the structural types and design methods of subgrade bed for high speed railways in China, Japan, France, Germany, the United States and other countries based on the study and analysis of existing literature and combined with the research results and practices of high speed railway subgrade engineering at home and abroad.

It is found that in foreign countries, the layered reinforced structure is generally adopted for the subgrade bed of high speed railways, and the unified double-layer or multi-layer structure is adopted for the surface layer of subgrade bed, while the simple structure is adopted in China; in foreign countries, different inspection parameters are adopted to evaluate the compaction state of fillers according to their respective understanding and practice, while in China, compaction coefficient, subsoil coefficient and dynamic deformation modulus are adopted for such evaluation; in foreign countries, the subgrade top deformation control method, the subgrade bottom deformation control method, the subsurface fill strength control method are mainly adopted in subgrade bed structure design of high speed railways, while in China, dynamic deformation control of subgrade surface and dynamic strain control of subgrade bed bottom layer is adopted in the design. However, the cumulative deformation of subgrade caused by train cyclic vibration load is not considered in the existing design methods.

This paper introduces a new subgrade structure design method based on whole-process dynamics analysis that meets subgrade functional requirements and is established on the basis of the existing research at home and abroad on prediction methods for cumulative deformation of subgrade soil.

Social relationships play an important role in organizational entrepreneurship. They are crucial to entrepreneurs’ decisions because, despite the bleeding-edge technological advancements observed nowadays, entrepreneurs as human beings will always strive to be social. During the COVID-19 pandemic many companies moved activities into the virtual world and as a result offline Social relationships became rarer, but as it turns out, even more valuable, likewise, the inter-organizational cooperation enabling many companies to survive.

This chapter aims to develop knowledge about entrepreneurs’ SR and their links with inter-organizational cooperation. The results of an integrative systematic literature review show that the concept of Social relationships, although often investigated, lacks a clear definition, conceptualization, and operationalization. This chapter revealed a great diversity of definitions for Social relationships, including different scopes of meaning and levels of analysis. The authors identify 10 building blocks and nine sources of entrepreneurs’ Social relationships. The authors offer an original typology of Social relationships using 12 criteria. Interestingly, with regard to building blocks, besides those frequently considered such as trust, reciprocity and commitment, the authors also point to others more rarely and narrowly discussed, such as gratitude, satisfaction and affection. Similarly, the authors discuss the varied scope of sources, including workplace, family/friendship, past relationships, and ethnic or religious bonds. The findings of this study point to a variety of links between Social relationships and inter-organizational cooperation, including their positive and negative influences on one another. These links appear to be extremely dynamic, bi-directional and highly complex.