Retrospective and prospective review of the generalized nonlinear strength theory for geomaterials

Strength theory is the basic theory for calculating and designing the strength of engineering materials in civil,hydraulic,mechanical,aerospace,military,and other engineering disciplines.Therefore,the comprehensive study of the generalized nonlinear strength theory(GNST)of geomaterials has significance for the construction of engineering rock strength.This paper reviews the GNST of geomaterials to demonstrate the research status of nonlinear strength characteristics of geomaterials under complex stress paths.First,it systematically summarizes the research progress of GNST(classical and empirical criteria).Then,the latest research the authors conducted over the past five years on the GNST is introduced,and a generalized three-dimensional(3D)nonlinear Hoek‒Brown(HB)criterion(NGHB criterion)is proposed for practical applications.This criterion can be degenerated into the existing three modified HB criteria and has a better prediction performance.The strength prediction errors for six rocks and two in-situ rock masses are 2.0724%-3.5091%and 1.0144%-3.2321%,respectively.Finally,the development and outlook of the GNST are expounded,and a new topic about the building strength index of rock mass and determining the strength of in-situ engineering rock mass is proposed.The summarization of the GNST provides theoretical traceability and optimization for constructing in-situ engineering rock mass strength.

Research on the Impact of Social Media Live-Streaming on Consumer Purchasing Behavior and Its Coping Strategies

Due to the rapid development of network technology and the popularity of live-streaming,more and more businesses and individuals are using live-streaming to promote their products,giving rise to a new marketing model of social media live-streaming.Based on the social media live-streaming market,businesses or enterprises focus on tapping into new consumer demand,and social media live-streaming marketing has gradually expanded into various fields.Based on the SOR theory,this paper discusses how to improve the coping strategies of consumer purchasing behavior through social media live-streaming by analyzing the representative factors affecting consumer purchasing behavior such as anchors,brands,and live-streaming content in social media live-streaming.The results of this study will contribute to a better understanding of the relationship between social media live-streaming marketing models and consumer purchasing behavior and will help to reveal the potentials and limitations of social media live-streaming,thus providing valuable ideas and scientific basis for social media live-streaming marketing strategies.

Impact of Nursing Interventions Based on Self- Efficacy Theory on HAMA and HAMD Scores in Patients with Hepatitis B Cirrhosis

Objective:To explore the effect of nursing interventions based on self-efficacy theory guidance on psychological stress indicators in patients with hepatitis B cirrhosis.Methods:70 patients with hepatitis B cirrhosis from October 2023 to May 2024 were selected and grouped by random number table.The observation group received nursing intervention based on self-efficacy theory,while the control group received routine nursing.The differences in psychological stress indicators,self-efficacy indicators,and nursing satisfaction were compared between the two groups.Results:Hamilton Anxiety Rating Scale(HAMA)and Hamilton Depression Rating Scale(HAMD)scores of the observation group were significantly lower than those of the control group(P<0.05);Chronic Disease Self-Efficacy Scale(CDSES)scores of the observation group were significantly higher than those of the control group(P<0.05);and nursing satisfaction scores of the observation group were significantly higher than those of the control group(P<0.05).Conclusion:Hepatitis B cirrhosis patients receiving nursing care based on self-efficacy theory can stimulate patients'self-efficacy,calm their emotions,and their overall satisfaction is high.

Level of stress among nurses and their adopted coping strategies

Objectives:This study was aimed at identifying the nurse’s level of stress and the coping mechanism adopted by them.Materials and Methods:A descriptive study was done to assess the level of stress and the coping strategies adopted by the nurses in a secondary hospital in North East India,Nagaland.A total enumerative sampling technique was used to select 94 samples for the study.The Nursing stress scale(NSS)by Gray-Toft and Anderson 1981 was used to assess stress,and the Ways of Coping Questionnaire was used.Results:Of 94 samples,68(72.34%)had a mild level of stress,25(26.59%)had a moderate level of stress,and only 1(0.06%)had a severe level of stress.Thirty-one(32.97%)used minimal coping strategies,and 63(67.02%)used moderate coping strategies.There was no significant association between the stress level and selected demographic variables such as age,marital status,and years of experience(all P>0.05).A significant association was found between the stresses of nurses and qualification of nurses(χ2=4.10,P=0.04).Conclusion:The study reveals that most nurses had mild levels of stress.Most nurses use moderate coping strategies to relieve their stressors at work.Thus,there is a need to emphasize the importance of using effective coping strategies for nurses to alleviate their stresses and anxiety in their workplace and even in their personal lives.

Assessing the range of blasting-induced cracks in the surrounding rock of deeply buried tunnels based on the unified strength theory

Blasting-induced cracks in the rock surrounding deeply buried tunnels can result in water gushing and rock mass collapse,posing significant safety risks.However,previous theoretical studies on the range of blasting-induced cracks often ignore the impact of the in-situ stress,especially that of the intermediate principal stress.The particle displacement−crack radius relationship was established in this paper by utilizing the blasthole cavity expansion equation,and theoretical analytical formulas of the stress−displacement relationship and the crack radius were derived with unified strength theory to accurately assess the range of cracks in deep surrounding rock under a blasting load.Parameter analysis showed that the crushing zone size was positively correlated with in-situ stress,intermediate principal stress,and detonation pressure,whereas negatively correlated with Poisson ratio and decoupling coefficient.The dilatancy angle-crushing zone size relationship exhibited nonmonotonic behavior.The relationships in the crushing zone and the fracture zone exhibited opposite trends under the influence of only in-situ stress or intermediate principal stress.As the in-situ stress increased from 0 to 70 MPa,the rate of change in the crack range and the attenuation rate of the peak vibration velocity gradually slowed.

AHermitian C^(2) Differential Reproducing Kernel Interpolation Meshless Method for the 3D Microstructure-Dependent Static Flexural Analysis of Simply Supported and Functionally Graded Microplates

This work develops a Hermitian C^(2) differential reproducing kernel interpolation meshless(DRKIM)method within the consistent couple stress theory(CCST)framework to study the three-dimensional(3D)microstructuredependent static flexural behavior of a functionally graded(FG)microplate subjected to mechanical loads and placed under full simple supports.In the formulation,we select the transverse stress and displacement components and their first-and second-order derivatives as primary variables.Then,we set up the differential reproducing conditions(DRCs)to obtain the shape functions of the Hermitian C^(2) differential reproducing kernel(DRK)interpolant’s derivatives without using direct differentiation.The interpolant’s shape function is combined with a primitive function that possesses Kronecker delta properties and an enrichment function that constituents DRCs.As a result,the primary variables and their first-and second-order derivatives satisfy the nodal interpolation properties.Subsequently,incorporating ourHermitianC^(2)DRKinterpolant intothe strong formof the3DCCST,we develop a DRKIM method to analyze the FG microplate’s 3D microstructure-dependent static flexural behavior.The Hermitian C^(2) DRKIM method is confirmed to be accurate and fast in its convergence rate by comparing the solutions it produces with the relevant 3D solutions available in the literature.Finally,the impact of essential factors on the transverse stresses,in-plane stresses,displacements,and couple stresses that are induced in the loaded microplate is examined.These factors include the length-to-thickness ratio,the material length-scale parameter,and the inhomogeneity index,which appear to be significant.

A novel binary effective medium model to describe the prepeak stressstrain relationship of combined bodies of rock-like material and rock

Combined bodies of rock-like material and rock are widely encountered in geotechnical engineering,such as tunnels and mines.The existing theoretical models describing the stress-strain relationship of a combined body lack a binary feature.Based on effective medium theory,this paper presents the governing equation of the“elastic modulus”for combined and single bodies under triaxial compressive tests.A binary effective medium model is then established.Based on the compressive experiment of concretegranite combined bodies,the feasibility of determining the stress threshold based on crack axial strain is discussed,and the model is verified.The model is further extended to coal-rock combined bodies of more diverse types,and the variation laws of the compressive mechanical parameters are then discussed.The results show that the fitting accuracy of the model with the experimental curves of the concretegranite combined bodies and various types of coal-rock combined bodies are over 95%.The crack axial strain method can replace the crack volumetric strain method,which clarifies the physical meanings of the model parameters.The variation laws of matrix parameters and crack parameters are discussed in depth and are expected to be more widely used in geotechnical engineering.

Deformation and Stress Analysis of the Deepwater Steel Lazy Wave Riser Subjected to Internal Solitary Waves

The dynamic response of the steel lazy wave riser(SLWR)subjected to the internal solitary wave is a key to assessing its application feasibility.The innovation of this paper is to study the dynamic response properties of the SLWR with large deformation characteristics under internal wave excitation.A numerical scheme of the SLWR is constructed using the slender-rod theory,and the internal solitary wave(ISW)with a two-layer seawater model is simulated by the extended Korteweg-deVries equation.The finite element method combined with the Newmark-βmethod is applied to discretize the equations and update the time integration.The ISW excitation combined with vessel motion on the dynamic deformation and stress of the SLWR is investigated,and extensive simulations of the ISW parameters,including the interface depth ratio and density difference,are carried out.Case calculation reveals that the displacement of the riser in the lower interface layer increases significantly under the ISW excitation,and the stresses at a part of both ends grow evidently.Moreover,the mean value of riser responses under a combination of vessel motion and ISW coincides with the ISW-induced ones.Furthermore,the dynamic responses along the whole riser,including the displacement amplitudes,bending moment amplitudes,and stress amplitudes,almost increase with the increase in interface depth ratios and density differences.

Perceived stress and coping capacities among frontline healthcare workers of AIIMS during COVID-19 pandemic:A cross-sectional study

Objective:To assess perceived stress and coping capacity of frontline health workers from AIIMS during COVID-19 pandemic.Methods:This cross-sectional study conducted from May to July 2021 enrolled 694 participants.An online questionnaire based on Google Forms was developed to collect the data.Participants were assessed using the validated Perceived Stress Scale and the Coping Resources Inventory Scale.Results:The age of participants were 27(23-52)years old.The majority of respondents(73.5%)felt moderately stressed.Of the 694 participants,83.0%of the 576 participants had average stress management skills.Sex,marital status,and profession were significantly associated with perceived stress.In addition,marital status and profession were significantly associated with coping capacity.Conclusions:The majority of participants have moderate stress levels and average coping skills.Frontline healthcare workers have to maintain mental and physical health.Achieving this requires early screening and stress management for healthcare workers.

The Impacts of Physical Exercise on Stress Coping and Well-Being in University Students in the Context of Leisure

This study aims at investigating the in-depth information regarding impacts of physical exercise on psychological well-being in university students with an emphasis on coping with stress in the context of leisure. A qualitative research, based on interview to draw findings in an inductive way, was conducted. Nine university students (N = 9) in a large mid-west university took part in a face- to face, semi-structured interviews using ten open-ended questions with respect to benefits of leisure time physical exercise. The interview on the basis of phenomenological research examined what the participants experienced with leisure time physical exercise in conjunction with stress coping and mental health. Meaningful units of themes were induced with 24 initially drawn themes. These themes were reduced to 8 comprehensive constituent themes: self-efficacy, positive emotion, mind and body, health-behaviors, self-esteem, leisure, problem-focused coping, and positive expectancy. These reduced themes were finally boiled down to 6 integrated themes: positive emotion, unity of mind and body, heightened self-esteem, leisure, problem-focused coping, and self-regulation of health behavior. This research may shed a light in illuminating potential mechanism of how regular physical exercise is conducive to enhanced health behavior as well as effective stress coping in university students in the context of leisure. In particular, this research appears to be meaningful in suggesting that regular leisure-time physical exercise can lead to an effective problem-focused coping through elicitation of positive emotion.

APPLICATION OF PARAMETRIC DERIVATION METHOD TO THE CALCULATION OF PEIERLS ENERGY AND PEIERLS STRESS IN LATTICE THEORY

Applying the parametric derivation method, Peierls energy and Peierls stress are calculated with a non-sinusoidal force law in the lattice theory, while the results obtained by the power-series expansion according to sinusoidal law can be deduced as a limiting case of non- sinusoidal law. The simplified expressions of Peierls energy and Peierls stress are obtained for the limit of wide and narrow. Peierls energy and Peierls stress decrease monotonically with the factor of modification of force law. Present results can be used expediently for prediction of the correct order of magnitude of Peierls stress for materials.

RENEWAL OF BASIC LAWS AND PRINCIPLES FOR POLAR CON-TINUUM THEORIES (Ⅱ)—MICROMORPHIC CONTINUUM THEORY AND COUPLE STRESS THEORY

The purpose is to reestablish the balance laws of momentum, angular momentum and energy and to derive the corresponding local and nonlocal balance equations for micromorphic continuum mechanics and couple stress theory. The desired results for micromorphic continuum mechanics and couple stress theory are naturally obtained via direct transitions and reductions from the coupled conservation law of energy for micropolar continuum theory, respectively. The basic balance laws and equations for micromorphic continuum mechanics and couple stress theory are constituted by combining these results derived here and the traditional conservation laws and equations of mass and microinertia and the entropy inequality. The incomplete degrees of the former related continuum theories are clarified. Finally, some special cases are conveniently derived.

Linear and nonlinear torsional free vibration of functionally graded micro/nano-tubes based on modified couple stress theory

The linear and nonlinear torsional free vibration analyses of functionMly graded micro/nuno-tubes （FGMTs） are analytically investigated based on the couple stress theory. The employed non-classical continuum theory contains one material length scale parameter, which can capture the small scale effect. The FGMT model accounts for the through-radius power-law variation of a two-constituent material. Hamilton＇s principle is used to develop the non-classical nonlinear governing equation. To study the effect of the boundary conditions, two types of end conditions, i.e., fixed-fixed and fixed-free, are considered. The derived boundary value governing equation is of the fourthorder, and is solved by the homotopy analysis method （HAM）. This method is based on the Taylor series with an embedded parameter and is capable of providing very good approximations by means of only a few terms, if the initial guess and the auxiliary linear operator are properly selected. The analytical expressions are developed for the linear and nonlinear natural frequencies, which can be conveniently used to investigate the effects of the dimensionless length scale parameter, the material gradient index, and the vibration amplitude on the natural frequencies of FGMTs.

The Effect of Aerobic Indoor Exercise Compared with Green Exercise on Different Symptoms of Depression: An Investigation of Psychological Mediators of Stress and Coping

Objectives: Considering the growing need for using a variety of new nonpharmacological methods in treating depression, this quasi experimental study was conducted to investigate the effect of aerobic indoor exercise in a gym compared with green exercise in an outdoor green environment of an urban park on triple categories of affective, cognitive and somatic symptoms of depression and to examine its psychological mediators of perceived stress and coping strategies. Methods: Forty six female outpatients with major depressive disorder were divided into 3 conditions of indoor exercise + routine pharmacotherapy (n = 15), green exercise + routine pharmacotherapy (n = 15), and a routine pharmacotherapy alone as the control group (n = 16). The exercise used for both indoor and green exercise conditions consisted of 36 one hour sessions (three times per week) with an intensity of 50% - 70% of the maximum heart rate. The participants completed the pre- and post-intervention depression, stress and coping questionnaires including Beck Depression Inventory-II, Perceived Stress Scale and Coping Inventory for Stressful Situations. Results: The findings indicated a significant decrease in the post-intervention scores of all three categories of affective, cognitive and somatic symptoms of depression and perceived stress in both exercise groups compared with the control group, but there was no significant difference between two exercise groups. With respect to the use of problem-focused, emotion-focused and avoidant-focused coping methods, there was no significant difference between post-intervention scores of all groups. Conclusion: In the clinical settings, both of the indoor exercise and green exercise programs can help to further improvement in all three categories of affective, cognitive and somatic symptoms of depression as an adjunct (or independent) treatment to the same degree, especially mediated by reducing the amount of perceived stress, but not through any significant changes in cognitive-behavioral coping strategies.

Deformation mechanism of high-stress and broken-expansion surrounding rock and supporting optimization based on the gray correlation theory

Aiming at the large deformation and support problems of high-stress and broken-expansion surrounding rock, and taking 1 000 m level roadway of Mine II in Jinchuan as the research object, an investigation on the deformation and damage of roadway surrounding rock and an analysis of its mechanism were carried out. The gray correlation theory was used in support scheme optimization design. First, causes and mechanism of deformation of the 1 000 m horizontal transport channel were analyzed through field investigation, laboratory test and data processing methods. We arguued that poor engineering geological conditions and deep pressure increases were the main factors, and the deformation mechanism was mainly the ground deformation pressure. Second, the gray correlation theory was used to construct supporting optimization decision method in the deep roadway. This method more comprehensively considers various factors, including construction, costs, and supporting material functions. The combined support with pre-stressed anchor cables, shotcrete layer, bolt and metal net was put forward according to the actual roadway engineering characteristics. Finally, 4 support schemes were put forward for new roadways. The gray relational theory was applied to optimizing the supporting method, undertaking technical and economic comparison to obtain the correlation degree, and accordingly the schemes were evaluated. It was concluded as follows： the best was the flexible retaining scheme using the steel strand anchor; the second best was the one using plate anchors on the top and rigid common screw steel bolt on the two sides; the ttiird was; the rigid common screw steel bolt in full section of roadway; and the worst is the planished steel rigid support. The optimized scheme was applied to the 1000 m level of new excavation roadway. The results show that the roadway surrounding rock can reach a stable state after 5 to 6 months monitoring, with a convergence rate less than 1 mm/d.

Stress and coping styles among nursing students during the initial period of the clinical practicum:A cross-section study

Objectives:This study aimed to explore the level of stress,types of stressors,type of coping styles,and factors influencing stress levels and coping styles among nursing students during the initial period of the clinical practicum.Methods:A cross-sectional survey design was used.In September 2017,participants were recruited from a tertiary hospital in Zhejiang Province,China,using a convenience sampling method.A demographic characteristics questionnaire,the Intern Nursing Student Stressor Scale,and the Simple Coping Style Questionnaire were used to collect data.Data were analyzed using descriptive analysis,independent sample t-tests,one-way analysis of variance,Pearson’s correlation analysis,and multiple linear regres-sion analysis.Results:A total of 158 nursing students were recruited,most of whom were female,undergraduates,and from rural areas.The nursing students perceived a moderate level of stress during the initial period of the clinical practicum.The need for knowledge and skills was the most common source of stress.Positive coping styles were most commonly adopted.Nursing students who were undergraduates,only children,and chose nursing major involuntarily experienced higher stress levels than those who were junior college students,not only children,and chose nursing major voluntarily.Nursing undergraduates were more likely to use positive coping styles than junior college students.Male nursing students and those experiencing higher stress levels related to the“environment and equipment of the wards”and the“nature and content of the work”were more likely to use negative coping styles.Conclusion:Nursing educators should offer targeted guidance based on the stress reported during the clinical practicum and the demographic characteristics of the nursing students.Guidance should be provided to encourage nursing students to adopt effective coping strategies and reduce stress.

A MATHEMATICAL THEORY OF MATERIALS WITH ELASTIC RANGE AND THE DEFINITION OF BACK STRESS TENSOR

In this paper, the theory of materi als with elastic range by Lucchesi and Podio_Guidugli(1988) has been generalized . It has also shown that there are some difficulties on the definition of back s tress as the “center” of the yield surface in the Cauchy space. The back stres s tensor is Lagrangian,and must be defined in the Lagrangian stress space.

The Effect of Aerobic Exercise on Different Symptoms of Depression: An Investigation of Psychological Mechanisms of Stress and Coping

Objectives: Considering the growing need for encouraging greater use of a variety of non-pharmacological methods in treating depression, the aim of this quasi experimental study was to examine the effect of aerobic exercise on triple categories of affective, cognitive and somatic symptoms of depression and to investigate its psychological mediators of perceived stress and coping strategies. Methods: Forty five female outpatients with major depressive disorder were divided into three groups including exercise + usual pharmacotherapy (n = 15), psychotherapy + usual pharmacotherapy (n = 14) and a control group receiving only usual pharmacotherapy (n = 16). The exercise used was included 36 one hour session (three sessions per week) with a low to medium intensity of 50% to 70% of the maximal heart rate. The psychotherapy used in this study was the behavioral activation treatment for depression revised. The Persian version of Beck Depression Inventory-II, Perceived Stress Scale and Coping Inventory for Stressful Situations were applied to assess the pre- and post-intervention depression, perceived stress, and coping strategies. Results: The findings indicated a significant decrease in the post-intervention scores of all three categories of affective, cognitive and somatic symptoms of depression and the perceived stress level in the adjunctive exercise and psychotherapy conditions compared with the control condition (p = 0.001), but there was no significant difference between the exercise and psychotherapy groups. In addition, no significant improvement was observed regarding the problem-centered, emotion-centered and avoidant-centered stress coping methods in the post-intervention scores of the exercise group compared with the control group. Conclusion: An adjunctive aerobic exercise program can be as effective as adding the psychotherapy to usual pharmacotherapy in further improvement in all three categories of depression symptoms especially mediated by reducing the amount of perceived stress, but not through any significant change in cognitive-behavioral coping strategies.

Sequential Mediating Effect of Proactive Coping and Perceived Stress in the Relationships between Self-Esteem Stability and Life Satisfaction

While the effect of self-esteem stability on life satisfaction is widely verified,it is not very known how coping strategies explain this relationship.The present study focused on proactive coping,a preliminary step to minimize the impact of expected stressors,and a process of recognizing stressful events as challenges and actively managing them.Specifically,this study(N=280)examined whether proactive coping and perceived stress mediated the relationship between self-esteem stability and life satisfaction in a sequential manner.The results indicate that proactive coping and perceived stress sequentially mediated the relationship between self-esteem stability and life satisfaction,respectively.This demonstrates that proactive coping and perceived stress are factors that link self-esteem and life satisfaction.However,there was no direct effect between self-esteem and life satisfaction.These findings suggest the need to consider combining proactive coping interventions to increase the effectiveness of a self-esteem stability promotion program.The practical implications and suggestions for future research are also discussed.

Perceived Stress and Coping Strategies in Entry-Level Doctor of Physical Therapy Students Enrolled in a Hybrid-Learning Curriculum during the Pandemic

Physical therapy students can experience elevated levels of stress due to the pressure to be successful, changes in the environment, personal concerns, the lack of spare time, increased work, or financial burdens. The purpose of this study was to examine the perceived stress and coping strategies of Doctor of Physical Therapy (DPT) students enrolled in a hybrid-learning curriculum during the COVID-19 pademic. A total of 73 students enrolled in the DPT hybrid-learning curriculum responded to a survey which consisted of socio-demographics, the 10-item Perceived Stress Scale (PSS), and the 28-item Brief COPE. A general question regarding stress relating to COVID-19 was presented as a sliding percentage. Data analysis included a Spearman correlation, a Kruskal-Wallis test, and a linear regression to evaluate coping mechanisms against PSS scores. The mean (± SD) score on the PSS was 22.65 (± 10.21) and the Brief COPE was 59.18 (± 10.61). A non-significant negative correlation was found between the PSS and Brief COPE (r = -0.024). A third of the variation in the perceived stress score could be accounted for by students utilizing coping mechanisms regardless of other factors (R2 = 0.35). No significant differences were found when comparing PSS and Brief Cope to age, hours worked per week and term. Perceived stress was higher in females compared to males, but the results were not significant. Stress related to COVID-19 mean percentage reported by DPT students was 49.03%. During a global pandemic, DPT students enrolled in a hybrid-learning curriculum reported elevated levels of stress but reported higher adaptive versus maladaptive coping strategies. It can be beneficial that universities evaluate the stress and coping methods of students to potentially avoid the negative impacts of stress.