Expansion Theory Research Articles

Retrieving Materialism: The Continued Relevance of Dorothy Smith

In this article, I argue that Smith’s continued relevance coincides with more recent retrievals of Marx-inspired materialism. This materialism and the associated understanding of human beings—the social, language, and world people share in common—certainly do not capture all there is to say about Smith’s eclectic and expansive social theory. However, the material dimension distinguishes her work from many other feminist sociologies and results in her continued relevance as a thinker who brings to the table another way of doing feminist sociology. I illustrate this by showing how Smith’s Marx-inspired materialism and its associated understanding of language offer a productive and timely alternative to the feminist social theory of anti-categorical intersectional theory and new materialist theory.

Cavity expansions in two silty tailings with high degrees of saturation and a comparison to CPT results

Tailings, being mixtures of water and soil-sized particles, and sometimes air, are waste products generated by mining. They are stored on sites, often contained by embankments, forming what are known as tailings storage facilities (TSFs). Assessments of the state and strength of tailings inside a TSF may involve in situ tests, especially the cone penetration test (CPT) and occasionally the pressuremeter test (PMT). Cavity expansion theory may assist the interpretation of these tests. The coexistence of air and water in the pore space means the tailings is unsaturated and gives rise to a suction. The suction, and the extent to which air and/or water can drain through the pores, affects the cavity expansion results as well as CPT and PMT results. The cavity expansion problem is solved here considering four possible drainage conditions, constant suction, constant water mass, constant contribution of suction to the effective stress, and a constant air and water mass (closed system). It is reasoned that solutions for a closed system are relevant to the interpretations of CPTs and PMTs when < 15 % of the tailings volume is occupied by air, and that the constant effective stress condition (which is a close approximation to a constant water mass condition) is relevant when larger air volumes are present. By considering CPT data it is observed that linear proportionalities exist between effective cone penetration resistances and cavity wall pressures. The cavity expansion results are then converted to equivalent CPT results and used to construct charts which relate the normalised cone penetration resistance to the initial state parameter. The charts have use for unsaturated conditions and a variety of air volume fractions, as well as saturated conditions when the cone penetration rate is slow enough so drained conditions prevail or fast enough so that undrained conditions prevail.

Direct Moment Expansion Theory of the Pair Unit-cell Model in Phase Transition

Direct Moment Expansion Theory of the Pair Unit-cell Model in Phase Transition

Investigating the acceptance and use of massive open online courses (MOOCs) for health informatics education

BackgroundThis study investigated the acceptance and use of massive open online courses (MOOCs) among health informatics educators and students in Saudi Arabian academic institutions. A theoretical model based on the unified theory of acceptance and use of technology (UTAUT), self-determination theory (SDT), and channel expansion theory (CET) was used to identify factors that affect MOOC adoption in health informatics education.MethodsA survey research design was employed, and cross-sectional data were collected from health informatics instructors and students in academic institutions in Saudi Arabia. A total of 145 completed responses were used in the final analysis of the data.ResultsThe findings indicated that performance and effort expectancy were important factors that could predict the acceptance and use of MOOCs among health informatics instructors and students. Additionally, perceived media richness affected the actual use of health informatics MOOCs among students and instructors in Saudi Arabian academic institutions. The results of this study show that autonomy, relatedness, and competence must be considered in the design of health informatics MOOCs.ConclusionsA combination of these models can effectively explain the adoption and use of MOOCs in emerging fields such as health informatics.

Analysis of Factors Affecting User Inclination to use Virtual Education Exhibitions in the Post Pandemic Covid-19 Era: Case Study in Indonesia

Social distancing policies during the COVID-19 period have opened a space for interventions in the use of digital technology that was previously rejected by the public. Currently, most of the community activities have been carried out online, including those related to education, such as hosting virtual exhibitions with an educational purpose. Virtual exhibitions (VE) are online exhibitions that display information on specific topics. However, to the best of our knowledge, research on VE in the educational context is still lacking. This study aims to identify the variables that affect users' intentions to attend the virtual exhibition frequently. The channel expansion theory, flow theory, technology acceptance model, and expectation confirmation theory serve as the foundation for the research model that is constructed. The model was tested using data from 321 respondents who had visited VE, then analyzed using Structural Equation Modeling (SEM) with the aid of the SmartPLS application version 3.3.3. The findings show that 11 factors significantly influence the intention to continue using VE, while the other 2 factors have no significant influence. Thus, perceived usefulness has a significant effect on satisfaction and continued use intention to use VE, but not on perceived enjoyment. Furthermore, the perceived ease of use of VE has a significant impact on perceived usefulness and perceived enjoyment. However, media richness does not significantly affect perceived enjoyment. It's just that media richness influences perceived ease of use significantly. Confirmation also has a significant impact on perceived enjoyment, perceived usefulness, and satisfaction. Perceived enjoyment has a significant effect on satisfaction and continued use intention, and satisfaction has a significant effect on continued use intention to use VE. The findings are useful for VE providers and developers in developing a transformation strategy to increase the intention to use VE in every educational exhibition.

Design and performance evaluation of a high temperature axisymmetric plug nozzle

In this study, a method for designing supersonic nozzles with axisymmetric plugs at high temperature has been proposed. The approach is based on the theory of Prandtl-Mayer expansion at high temperatures using the method of characteristics. For this purpose, a code in FORTRAN language was developed in order to obtain the nozzle design. Once the latter was obtained, we were interested in the evolution of the thermodynamic parameters of the flow such as pressure, temperature, and Mach number. The results achieved were confronted with those obtained for a perfect gas model. Regarding the design parameters (length, section ratio, thrust coefficient and mass coefficient), we found that the PG model gives very satisfactory results for values of 𝑀𝑀 and 𝑇𝑇0 below 2.00 and 1000 𝐾𝐾, respectively. As 𝑀𝑀𝐸𝐸 and 𝑇𝑇0 increase, this affects performance, requiring the use of our HT model to correct the calculations. In order to minimize the weight of this nozzle, this research is investigating the truncation of the Plug nozzle to increase its performances. All calculations were performed for air.

Application of the Method of Fast Expansions to Construction of a Trajectory of Movement of a Body with Variable Mass from Its Initial Position in a Gained Final Position in a Gravitational Field

An analytical solution of the problem of the movement of a spacecraft from the starting point to the final point in a certain time is given. First, the method of fast sine expansions is used. The space problem considered here is essentially non-linear, what necessitates the use of trigonometric interpolation methods, which surpass all known interpolations in accuracy and simplicity. In this case, the problem of calculating Fourier coefficients by integral formulas is replaced by the solution of an orthogonal interpolation system. In this regard, two cases are considered on the segment \(\left[ {0,a} \right]\): universal interpolation and trigonometric sine and cosine interpolations. A theorem on the rapid decrease of expansion coefficients is proved, and a compact formula for calculating the interpolation coefficients is obtained. A general theory of fast expansions is given. It is shown that in this case, the Fourier coefficients decrease significantly faster with the growth of the ordinal number compared to the Fourier coefficients in the classical case. This property makes it possible to significantly reduce the number of terms taken into account in the Fourier series, significantly increase the accuracy of calculations and reduce the amount of calculations on a computer. The analysis of the obtained solutions of the spacecraft motion problem is carried out and their comparison with the exact solution of the test problem is proposed. An approximate solution by the method of fast expansions can be taken as an exact one, since the input data of the problem used from reference books have a higher error.

Study on Shielding Effect of the Pile Group in a Soft-Soil Foundation

Pile groups are frequently employed to reinforce soft soil foundations, while the piling process frequently disturbs the adjacent foundation. The shielding effect, which prevents the transmission of disturbances from pile installation, is indispensable for minimizing engineering disturbances and optimizing pile group construction techniques. However, current research focuses predominantly on characterizing the phenomenon of shielding, with a limited exploration of the mechanism. To eliminate the limitation, a numerical investigation of the shielding mechanism of pile groups in a pile–soil system is performed this study. Using the finite difference program FLAC3D and the cavity expansion theory, a three-dimensional numerical model of a pile–soil foundation was created. During the sequential penetration of piles, the response characteristics of the soil surrounding the piles were investigated. Displacement field was first investigated to determine the presence of shielding effects in the pile group and then highlighted the effective role of the existing piles in controlling deformation. Furthermore, through a combined analysis of the stress and strain fields during piling, the mechanism of the shielding effect induced by pile construction is proposed, which is attributed to the direct obstruction effect of piles and the “soil arching effect” created by the soil between piles. The former is reflected by the direct barrier of the existing pile to the soil displacement induced via the installation of the new piles. The latter is reflected by the obstruction of soil between two existing piles to the displacement of soil passing through the two existing piles. This research provides a comprehensive understanding of the mechanical behavior of the pile–soil system and has practical implications for controlling disturbances and optimizing construction techniques in piling engineering projects.

Expansion Theory of Deng’s Metric in [0,1]-Topology

The aim of this paper is to focus on a fuzzy metric called Deng’s metric in [0,1]-topology. Firstly, we will extend the domain of this metric function from M0×M0 to M×M, where M0 and M are defined as the sets of all special fuzzy points and all standard fuzzy points, respectively. Secondly, we will further extend this metric to the completely distributive lattice LX and, based on this extension result, we will compare this metric with the other two fuzzy metrics: Erceg’s metric and Yang-Shi’s metric, and then reveal some of its interesting properties, particularly including its quotient space. Thirdly, we will investigate the relationship between Deng’s metric and Yang-Shi’s metric and prove that a Deng’s metric must be a Yang-Shi’s metric on IX, and consequently an Erceg’s metric. Finally, we will show that a Deng’s metric on IX must be Q−C1, and Deng’s metric topology and its uniform structure are Erceg’s metric topology and Hutton’s uniform structure, respectively.

An analytical model to predict the radial deformation of surrounding rock during shaft construction via shaft boring Machine

During shaft construction using a shaft boring machine (SBM), the extrusion effect caused by the thrusts of the shaft boring machine can lead to excessive radial deformation and local failure of the surrounding rock. To calculate the rock radial deformation, the deformation mechanism of the rock during the SBM driving process was investigated via numerical simulation. Then, a new analytical model was proposed to calculate the radial deformation, and the extrusion effect of the shaft boring machine was innovatively considered using an additional vertical stress in the proposed model. The equation of the vertical additional stress can be derived by the limit equilibrium method, and the radial deformation of the surrounding rock is calculated using cavity expansion theory. The effectiveness of the proposed model was verified by numerical calculation results, and a parametrical discussion was performed to study the impacts of the thrusts of the cutterhead and grippers. The results indicate that the rock radial deformation calculated by the proposed model is more accurate than that calculated by the existing model. The maximum radial deformation of the surrounding rock occurs at the transition interface. The thrusts of the shaft boring machine’s cutterhead and grippers are the major factors affecting the rock radial deformation. The increase in the cutterhead thrusts or the decrease in the gripper thrusts will lead to an increase in rock radial deformation. Therefore, an appropriate combination of the shaft boring machine thrusts is beneficial for restricting the radial deformation of the surrounding rock.

High order asymptotic expansion for Wiener functionals

Combining the Malliavin calculus with Fourier techniques, we develop a high-order asymptotic expansion theory for general Wiener functionals. Our method gives an expansion of the characteristic functional and of the local density of a Wiener functional up to an arbitrary order. The asymptotic expansion is distributional. Except for the non-degeneracy of the limit covariance matrix, we do not assume any condition of non-degeneracy of the Malliavin covariance like a non-degeneracy condition for temporally local characteristic functions so far assumed in the theory for mixing processes, that corresponds to the Cramér condition in the classical setting. Moreover, our method does not require the Markovian property used in the mixing approach. An application to the stochastic wave equation with space–time white noise is discusses.

Cavity reverse expansion considering elastoplastic unloading and application in cast-in-situ bored piles

The construction process of a cast-in-situ bored pile is too complicated to be described by the cavity expansion theory with a single process. An exact unified semi-analytical solution for both cylindrical and spherical cavities reverse expansion after unloading in drained soil is developed. The non-associated Mohr-Coulomb model and definition of logarithmic strain are adopted in the reverse plastic zone. This model can be used to solve the stress and displacement fields of the soil around a bored pile along both the horizontal and depth directions. Parametric analysis shows that the effect of the unloading phase does not change the ultimate pressure of cavity reverse expansion compared with in situ expansion. The cavity cannot re-expand to its initial radius even though the cavity pressure reloads to the initial value. The increase of internal friction angle, cohesion, and Young's modulus has a positive effect on radius recovery, while the dilatancy angle has a negative effect. A simulation of the construction process of cast-in-situ bored piles is presented, where the role of boring, mud wall protection, and concrete placement is defined. An example that describes the stress and displacement fields around a pile shows that the total radial displacement of soil around the pile is dominated by contraction displacement. And it is closely related to depth and horizontal distance. The results of both parameter analysis and example analysis demonstrate that a low reverse cavity pressure corresponds to a stress-reduction area surrounding the cavity.

Performance of screw piles in thick collapsible loess

The bearing capacity of the composite foundation would be significantly increased by the squeezing effect of soil displacement screw pile. To investigate the effect of soil displacement screw pile treatment on the large-thickness collapsible loess foundation, full-scale field tests and pore expansion theory were used to compare the physical and mechanical properties of the soil around the pile before and after soil displacement screw pile treatment. It was found that the maximum influence range of a single pile in loess foundation was 3D, and the effective influence range was 2.5D. Compared with natural foundation, the average dry density of soil between two and three piles increased by 23 % and 15 %, and the compression coefficient decreased by 57 % and 38 %, respectively, when the pile spacing was 2.0D and 2.5D. The collapsibility coefficient and self-weight collapsibility of soil between two and three piles were far less than 0.015 when the pile spacing was less than or equal to 2.5D. The soil deformation caused by compaction was mainly plastic deformation. The plastic zone radius calculated by pore expansion theory can be used to estimate the compaction range of soil displacement screw piles in large-thickness loess regions. When the pile spacing was 2D and 2.5D, compared with the natural foundation, the characteristic values of soil bearing capacity between piles increased by 60 % and 30 %, that soil displacement screw pile of plain soil composite foundation increased by 220 % and 200 %, and that of plain concrete soil displacement screw pile increases by 450 % and 400 %, respectively. It shows that a soil displacement screw pile can significantly increase the bearing capacity of a large-thickness collapsible loess foundation. When the area replacement rate was 0.145–0.23, the pile-soil stress ratio of soil displacement screw piles in large-thickness collapsible loess region ranged from 2.6 to 4.7.

A new boson expansion theory utilizing a norm operator

Abstract We propose a new boson expansion method using a norm operator. The small parameter expansion, in which the boson approximation becomes the zeroth-order approximation, requires the double commutation relations between phonon operators that are not closed between the phonon excitation modes adopted as boson excitations. This results in an infinite expansion regardless of whether the type of the boson expansion is Hermitian or non-Hermitian. The small parameter expansion does not hold when the commutation relations are closed. The norm operator is expressed as a function of the number operator in the physical subspace, which enables us to obtain substantially a finite boson expansion regardless of the Hermitian or non-Hermitian type. We also point out the problems of the conventional boson expansion methods. The normal-ordered linked-cluster expansion theory has failed to refute Marshalek’s claim that KT-1 and KT-2 are of chimerical boson expansion. The Dyson boson expansion theory does not have exceptional superiority over other types. Previous studies using the boson expansion methods should be re-examined.

A Comparative Study on the Identification Methods of Urban–Rural Integration Zones from the Perspective of Symbiosis Theory and Urban Expansion Theory

Urban–rural integration zones are areas with the most prominent and complex contradictions in economic and social, humanistic and geographical, and urban–rural contexts. Properly identifying such zones is essential for promoting urban–rural integrated development and rural revitalization efforts. In this study, symbiosis theory and urban expansion theory are employed to analyze and identify the spatial characteristics of urban–rural integration zones in the main urban area of Dalian City. Two distinct methods, namely the G-statistic (G-S) method and the urban–urban–rural integration zone–rural gradient model (U-URIZ-R GM) method, are used to delimit these zones. Furthermore, the results of these methods are compared and analyzed to explore their respective practical applications. The results indicate that both methods produce satisfactory identification outcomes for delimiting urban–rural integration zones in the main urban area of Dalian. Specifically, the identified urban–rural integration zones are predominantly situated in the northwest and south regions, aligning with the coastline and major transportation routes. However, hilly terrain is a crucial factor that influences the delimitation of urban–rural integration zones, and it is worth considering whether forested areas located in the urban fringe should be included based on the development needs of different cities. Notably, within the core area of Dalian’s main city, an extensive expanse of mountainous woodland exists, leading to limitations in the applicability of certain indicators within the index system, such as surface temperature and vegetation cover, for determining urban–rural integration zones. Symbiosis and urban expansion theories play a vital role in guiding the identification of urban–rural integration zones. Although both methods can be used to demarcate these zones, the G-statistics method is probably more useful in cities with significant topographical features, while the urban–urban–rural integration zone–rural gradient model is more appropriate for cities with less impact from topography on urban expansion.

Role of the single-particle dynamics in the transverse current autocorrelation function of a liquid metal.

A recent simulation study of the transverse current autocorrelation of the Lennard-Jones fluid [Guarini et al., Phys. Rev. E 107, 014139 (2023)] revealed that this function can be perfectly described within the exponential expansion theory [Barocchi et al., Phys. Rev. E 85, 022102 (2012)]. However, above a certain wavevector Q, not only transverse collective excitations were found to propagate in the fluid, but a second oscillatory component of unclear origin (therefore called X) must be considered to fully account for the time dependence of the correlation function. Here, we present an extended investigation of the transverse current autocorrelation of liquid Au as obtained by abinitio molecular dynamics in the very wide range of wavevectors 5.7 ≤ Q ≤ 32.8 nm-1 in order to also follow the behavior of the X component, if present, at large Q values. A joint analysis of the transverse current spectrum and its self-portion indicates that the second oscillatory component arises from the longitudinal dynamics, as suggested by its close resemblance with the previously determined component accounting for the longitudinal part of the density of states. We conclude that such a mode, albeit featuring a merely transverse property, fingerprints the effect of longitudinal collective excitations on single-particle dynamics, rather than arising from a possible coupling between transverse and longitudinal acoustic waves.

Statics of integrated origami and tensegrity systems

This study presents an explicit form of the static equilibrium equations of integrated origami and tensegrity systems. The analytical approach allows one to model and analyze the isolated origami and tensegrity paradigms as a whole system. The tensegrity and origami members are described by the nodal coordinates and hinge angels between the origami panels. The nonlinear static equations of the integrated system are derived by the Lagrangian method. By Taylor’s expansion theory, we also presented its linearized form. The developed approach is capable of conducting the following comprehensive statics studies for any integrated origami and tensegrity systems: (1) Performing loading analysis, where bars and strings can have elastic or plastic deformations. (2) Conducting infinitesimal and large deformation analysis, which is helpful in understanding the stress in structural members and actuation strategies. (3) Dealing with various kinds of boundary conditions, for example, fixing or applying static loads at any nodes in any direction (i.e., gravitational force, some specified forces, or moments). (4) Conducting stiffness analysis, including eigenvalues and their modes. Three examples, a Miura origami unit, an integrated tensegrity origami shelter, and a cable-driven Kresling structure, are carefully selected and studied. This study provides a deep insight into structures, materials, as well as performances. The integration idea also promotes our ability to design and build deployable structures at large.

The Relationship Between Trait Mindfulness and Well-Being in College Students: The Serial Mediation Role of Flow Experience and Sports Participation.

The current college students have a lot of mental pressure due to their heavy study, life and work burdens, and the incidence of college students' problems continues to rise. Sports are considered to be one of the best ways to improve the well-being of college students. However, the mechanism of college students' well-being is still unclear. This article is intended to exploring the mechanism of action of Trait Mindfulness (TM) on well-being in college students. Four hundred and ninety six college students were tested with Mindfulness Attention Awareness Scale, Flow Experience Scale, Physical Activity Rating Scale, and Subjective Well-being Scale. College students' trait mindfulness (TM) can predict well-being, college students' trait mindfulness (TM) can have an indirect impact on well-being through flow experience, and college students' trait mindfulness (TM) has an indirect impact on well-being through sports participation. In addition, flow experience and sports participation play a sequential mediating role between college students' trait mindfulness (TM) and well-being. Flow experience and sports participation play a sequential mediating role between college students' trait mindfulness(TM) and well-being. The current research results indicate that college students get well-being in sport activities. Trait mindfulness influences the behavioral tendency of sports participation through the mediation of thinking activities and cognitive function sequences. The results of this study provide a new literature reference for expanding the theory of positive emotion expansion and well-being. In addition, this study also provides an important basis for improving college students' well-being and college education.

The Impact of Emotional Experience on Tourists’ Cultural Identity and Behavior in the Cultural Heritage Tourism Context: An Empirical Study on Dunhuang Mogao Grottoes

The emotions perceived by tourists and their effects in the tourism context are increasingly highlighted in tourism studies. In the cultural heritage tourism context, tourists’ emotional experience comes from their cognitive evaluation of the natural environment and the humanistic environment and triggers deep cognitive processing and prosocial behavior, further building tourists’ identity with culture and enhancing their awareness and heritage conservation behavior. Based on the theory of emotional evaluation and positive emotional expansion and construction, this study constructed the research model of emotional arousal—positive emotional experience—tourists’ cultural identity—heritage protection behavior. Three hundred and ninety-seven tourists’ data were empirically tested using the World Heritage Site, the Dunhuang Mogao Grottoes, as a case site. The study found that in the cultural heritage tourism context, the cognitive evaluation of the natural and humanistic environment has the effect of inducing positive emotional experience among tourists; positive emotional experience positively influences tourists’ cultural identity and heritage conservation behavior; and they are part of the mediating variables of tourists’ emotion elicitation and cultural identity. The results of this study will further enrich the theoretical research on emotions in the cultural heritage tourism context and also help the relevant departments of cultural heritage tourism further enhance tourists’ cultural identity and heritage conservation behaviors from the perspective of tourists’ emotional experience. The future research could focus on investigating the emotional triggers’ impact on tourists’ cultural identity and heritage conservation behavior in relation to a particular cultural experience activity.

Anomalous Lateral Optical Force as a Manifestation of the Optical Transverse Spin

AbstractInteracting with an evanescent wave, an achiral particle can experience a lateral optical force (LOF) in a direction which is perpendicular to that of the illuminating photon momentum while the system apparently has the left–right symmetry. Here, using the Cartesian multipole expansion theory, a general relationship between LOF and spin and momentum is established. Most importantly, it is demonstrated that an anomalous LOF exerted on an isotropic achiral particle of arbitrary size and composition is proportional to the optical transverse spin in the incident evanescent wave that carries pure transverse spin associated with spin‐momentum locking. Manifesting itself as a mechanical consequence of the Berry phase effect, this anomalous LOF suggests a direct detectability of the transverse spin of light, as well as mimicking the transverse shift of light in the spin Hall effect of photons.