Merchant Model Research Articles

Fractional Viscoelastic Analysis of Transversely Isotropic Surrounding Rock Along Shallow Buried Elliptical Tunnel

ABSTRACTThis study introduces the fractional order Merchant model to analytically solve the stress and displacement fields of the transversely isotropic viscoelastic surrounding rock along shallow elliptical tunnels. First, the stress and displacement solutions of fractional order viscoelastic and transversely isotropic half planes under arbitrary loads are obtained using the Laplace transform and the elastic‐viscoelastic correspondence principle. Second, based on the above half plane solution and the solution of the deep buried elliptical tunnel problem, the Schwarz alternating method is introduced to obtain the analytical solution of the shallow buried elliptical tunnel. A MATLAB program is developed, and the accuracy of the theory and program in this study is verified by comparing it with the results of ABAQUS. Finally, the effects of transversely isotropic parameters, tunnel burial depth, and viscoelastic parameters on the stress and displacement of tunnel surrounding rock are analyzed.

Confucianism, Business Leaders, and Party-State Power in Contemporary China

From the beginning of the twenty-first century onwards, China has witnessed a Confucian revival in the business world. Often associated with a revitalisation of cultural tradition among the population, this new trend is characterised by a resurgence of the Confucian merchant (儒商, rushang) model, an ancient term that originally referred to a new type of merchants in the Ming Dynasty (1368–1644), who were close to literati circles. In parallel with this increasing interest in Confucianism by many economic elites, there has been an integration of certain elements of Confucianism into official political discourse through various moral edification campaigns. Based on an analysis of this new official discourse and the fieldwork we carried out between 2016 and 2020 within three private companies, this article aims to analyse interactions between three elements: Confucianism, party-state power, and business leaders claiming to be “Confucian.”

Research on Optimal Group-Purchase Threshold and Pricing Strategy of Community Group Purchase

This study delves into the rapidly evolving community group-buying model, specifically focusing on the determination of optimal group-buying thresholds and pricing strategies for merchants. Aiming to bridge the gap in the existing literature, the methodology employs optimization models, integrating a numerical analysis to construct and evaluate a single merchant model. The findings reveal a nuanced relationship: within a specific threshold interval, a unique group-purchase threshold exists where merchants can maximize profits by balancing group and ordinary sales. The study shows that factors like ordinary selling price, group-buying publicity, and associated costs significantly influence these thresholds and pricing strategies. A critical insight is the threshold’s variability in response to market conditions, highlighting a strategic balance for maximizing profitability. The research underscores the need for merchants to adapt their strategies in response to evolving market dynamics and consumer behaviors. However, the study acknowledges its limitations due to its theoretical nature and focus on the Chinese market, suggesting the potential for future empirical studies in diverse cultural and economic contexts. Overall, this research contributes both theoretically and practically by providing a foundational framework for merchants to optimize group-purchase thresholds and pricing strategies in the dynamic realm of community group buying.

Time-dependent transient response of piles partially embedded in layered viscoelastic saturated cross-anisotropic soils using a fractional-order Merchant model

A 3D analytical method is proposed for the lateral time-dependent response of monopiles partially embedded in stratified saturated viscoelastic cross-anisotropic soils under horizontal transient loads. Nevertheless, previous studies on ocean engineering have rarely considered the rheological properties of seabed materials. In this study, depending upon Biot's dynamical formulation, the linear elastic solution of the layered cross-anisotropic saturated soils due to lateral transient and vertical loads is solved using the analytical layer-element method (ALEM). The fractional-order Merchant model is adopted to describe the rheological deformation of the seabed, and the viscoelastic solution of the laminar cross-anisotropic saturated soils is derived by combining the elastic-viscoelastic transformation theory. Using the consolidation solution of the seabed as the kernel function, the pile-soil boundary problem is analyzed by the boundary element method (BEM) to obtain the BE equation of the viscoelastic saturated soils. The Timoshenko beam is employed to simulate the monopile, and based on the finite element method (FEM), the monopile is discretized into pile units to derive the FE matrix equation. Finally, the dynamic response formulation of the partially embedded offshore monopile is obtained by coupling the BE and FE equations through the coordination conditions of close contact between the Timoshenko beam and the seabed. The accuracy of the methodology is verified by comparing with the existing solutions and the numerical results from ABAQUS. And the effects of the transient load type, seabed viscosity, and pile properties on the horizontal response of partially embedded monopiles are explored.

Experimental Research on the Creep Behavior of the Interface of Compacted Loess and High-Density Polyethylene Geogrid

The stability of geogrid-reinforced soil structure is closely related to the interface characteristics between geogrid and soil. However, the creep behavior of the soil–geogrid interface is still unrevealed. In this study, using a modified stress-controlled pullout device, influence of the normal pressure, dry density, and water content on creep behavior of interface of compacted loess and high-density polyethylene (HDPE) geogrid is investigated. A three-parameter empirical model and a Merchant element model were established through fitting analysis. Analysis results show that the normal pressure, dry density, and water content have significant effects on the creep shear displacement of the reinforced soil interface. Under the same pullout level, creep displacement of the interface increases with the increase of water content and decreases with the increase of dry density and normal pressure. Both the three-parameter empirical model and Merchant element model can describe the creep characteristics of the reinforced soil interface. The Merchant model is more accurate in the early stage, while the three-parameter empirical model is more suitable for predicting the long-term creep deformation of the interface of compacted loess and geogrid.

Consolidation by Vertical Drains Considering the Rheological Characteristics of Soil under Depth and Time-Dependent Loading

Vertical drains have been widely used in soil improvement projects to accelerate consolidation and improve the strength of soft soil. Previous consolidation models are mainly based on instantaneous loading, which cannot reflect the actual time-variable loading condition. This paper presents a set of analytical solutions for consolidation with vertical drains under depth and time-dependent loading, involving one-step loading, multi-step loading, and cyclic loading. A four-element model, which is a combination of the Merchant model and Maxwell model, is introduced to consider the rheological characteristics of the soil. By simulating the results of a consolidation test, it is found that the four-element model is more accurate than the Merchant model in predicting the changes in pore pressure and settlement during the clay consolidation process. Based on the solutions obtained, several factors affecting consolidation behavior are investigated. It has been shown that the rheological behavior becomes more and more obvious at the later stage of consolidation with the decrease both in the modulus of the spring in the Kelvin body and the viscosity coefficient of the independent dashpot. With the increase in the viscosity coefficient of the dashpot in the Kelvin body, the rate of consolidation becomes faster at an initial stage but slower at a later stage. For cyclic loading, the consolidation degree in each cycle reaches a maximum at the end of unloading and reaches a minimum at the beginning of the loading.

Investigation of One-dimensional Consolidation of Fractional Derivative Model for Viscoelastic Saturated Soils Caused by the Groundwater Level Change

The Fractional calculus theory is introduced into the Merchant model to study the mechanical characteristics of saturated soils. Laplace transform is applied to the 1D consolidation and the fractional derivative Merchant model constitutive equations of saturated soils. In the transform domain, the analytical solutions of effective stress and settlement are obtained by solving the simultaneous equation. The Crump's method is used to the numerical inversion of Laplace transform, and the semi-analytical solution of the one-dimensional consolidation is obtained. A series of parameters, such as the fractional order, compression modulus, coefficient of viscosity, permeability coefficient and the variation models of groundwater level, are studied. Considering the continuity conditions, the 1D consolidation equation of single-layer saturated soil is generalized to multi-layer soils, and then the influence of different boundaries on several kinds of consolidation behavior was analyzed.

Analyses of Shear Angle in Orthogonal Cutting of Pine Wood

The determination of energy effects for wood machining processes, such as cutting power and cutting forces, is very useful in designing of manufacture process of wooden products. A more accurate prediction of cutting forces requires a correct determination of the shear angle value, which can be determined using various models. In this article, shear angle values for an orthogonal linear cutting process of pine wood are determined. The pine wood analysed was represented by two groups of samples with different moisture content levels, 12 % and 20 %. Three different models were used to determine the shear angle values: the Merchant model, which is based on the rake angle and the angle of friction, model based on chip compression ratios and Atkins model based on material properties (elements of fracture mechanics). The values obtained have been analysed for comparison. Results showed that the values of the shearing angles determined from the chip compression ratios turned out to be higher than the values from Merchant equation. The shear angles determined from the Atkins model are, as expected, lower than those determined from the Merchant model. Furthermore, the shear angle values for moisture content of 20 % are higher than for moisture content of 12 %.

An analytical model for 3D consolidation and creep process of layered fractional viscoelastic soils considering temperature effect

The behavior of long-term deformation of saturated soil under external loads has been one of the research focuses in geological engineering and geotechnical engineering. The temperature change, especially in the fields of geological radioactive waste disposal and geothermal system, usually significantly influence the consolidation and creep process of soils. This paper presents an analytical three-dimensional (3D) model for investigating the consolidation and creep behavior of layered soils considering temperature effect. Based on the analytical layer element elastic solution, fractional calculus theory and elastic-viscoelastic correspondence principle, an analytical 3D model is built by introducing the coefficients of thermal expansion and viscosity varying with temperature into the fractional Merchant model (FMM). Verifications against published analytical and numerical results are provided, followed by extensive parametric studies to investigate the effects of type of viscoelastic model, temperature change, fractional order and viscosity of FMM, layered characteristic of soils on consolidation and creep process. It’s evident that the present model predicts long-term behavior of layered viscoelastic soils well and can be used to evaluate the effect of temperature change on consolidation and creep process in geological engineering and geotechnical engineering.

THE EXPANSION OF OTA’s: BENEFITS AND RISKS

The aim of this paper is to analyze the advantages and disadvantages of OTA’s (Online Tourism Agencies). Many travelers today prefer OTA’s to look for advantageous tour packages and especially to make their reservations. They can make these reservations not only for accommodation but also for flights, excursions and why not, for other trips. OTA’s is an important component for a successful strategy, for all tour operators skilled in business. This way it helps them to reach more passengers and implicitly to make more reservations. But let’s not forget that paying a commission for each booking, it should balance the pros and cons. Due to intense competition, OTA is trying to remain financially sustainable. For this, however, it needs to involve its customers more, of course offering them superior value propositions. For this, however, a thorough understanding of consumption values ​​is needed. The role of OTA’s is becoming more and more important due to the ease of customers to compose a trip from the comfort of their home where they can also compare hotel prices and booking the choice on the Internet. An OTA’s agency organizes and sells accommodation, excursions and transportation to customers. It also organizes trips on an online platform for travelers. These OTAs are third parties that sell services on behalf of other companies. As a rule, these OTA’s offer many benefits. They have more comfort and a more self-serving approach. They also include a built-in booking system with which you can make instant bookings. OTA’s works in two models: Merchant model and Agency model. Merchant model is the model in which hotels sell rooms to OTA’s at a reduced or wholesale price. OTA’s then sells them to customers at a markup price. Agency model is the commission-based model in which OTA’s acts as a distribution partner. OTA’s receives full commission after the stay, and the hotel receives payment directly from the last customer and does not wait for the transfer of payment from third parties.

Semi‐analytical analysis of fractional derivative rheological consolidation considering the effect of self‐weight stress

AbstractStudies have revealed that rheological characteristics and self‐weight stress are nonnegligible during a consolidation process, especially for land reclamation projects or dredged soils. However, they are rarely considered simultaneously in traditional consolidation theories. This paper presents a general solution to the consolidation system of rheological soils that incorporates a fractional derivative model and self‐weight stress. First, the theory of the fractional derivative is introduced to the Merchant model to describe the consolidation behaviours of rheological soils, and the self‐weight stress of soils is simultaneously considered. Based on this model, the governing equation of a rheological consolidation system that considers self‐weight stress is obtained. Second, the analytical solutions of the effective stress and settlement in the Laplace domain are obtained by applying the Laplace transform to the consolidation governing equation. Further, the actual solutions in the real domain are obtained by a numerical Laplace transform inversion method (Abate's fixed Talbot method). Finally, the reliability and correctness of the consolidation theories and the proposed solutions are verified by comparing the calculated results with the degenerate solutions and experimental results in the existing literature. Furthermore, parametric studies are conducted to investigate the influence of rheological parameters and self‐weight parameters on the consolidation settlement and consolidation rate.

Analysis of one-dimensional rheological consolidation of double-layered soil with fractional derivative Merchant model and non-Darcian flow described by non-Newtonian index

Analysis of one-dimensional rheological consolidation of double-layered soil with fractional derivative Merchant model and non-Darcian flow described by non-Newtonian index

Fractional Time-Dependent Merchant Model for Coastal Soft Clay

Deng, H.Y.; Dai, G.L., and Azadi, M.R., 2020. Fractional time-dependent merchant model for coastal soft clay. In: Guido Aldana, P.A. and Kantamaneni, K. (eds.), Advances in Water Resources, Coastal Management, and Marine Science Technology. Journal of Coastal Research, Special Issue No. 104, pp. 825–831. Coconut Creek (Florida), ISSN 0749-0208.Soft clayey soils behave a time-dependent creep property subjected to sustained load. In order to describe the stress-strain-time property of soft clayey soil, a time-based fractional creep constitutive model is proposed based on the Caputo fractional calculus by applying the Abel dashpot in classical component model. The proposed fractional Merchant model is validated by drained creep test of coastal soft clay. The model parameters are obtained by fractional nonlinear fitting in terms of drained creep test results of coastal soft clay. Then the predicted results by the proposed fractional Merchant model and classical component models are also compared and validated with creep test results. It shows that the proposed fractional Merchant model is more approached to drained creep test results than classical component models. In particular, the proposed fractional Merchant model could well reduce the errors in the initial phase of creep compared with the classical model. It is indicated that the fractional Merchant model is superior in predicting drained creep property of coastal soft clay.

Time-dependent interaction between superstructure, raft and layered cross-anisotropic viscoelastic saturated soils

By introducing the elastic-viscoelastic correspondence principle and the integral transform technique, the extended precise integral solution to Biot's consolidation equation is derived for cross-anisotropic viscoelastic saturated soils based on the Merchant model. A displacement-time solution for a slowly changing load is obtained based on the above solution in the Laplace transformed domain, which is taken as the kernel function for the boundary element method (BEM). The Mindlin plate model is established by 8-node isoparametric finite element method (FEM), and the substructure condensation technique is employed to couple the stiffness matrices of the superstructure and the plate. With the BEM-FEM coupling method, a semi-analytical and semi-numerical solution is proposed for the interaction between layered cross-anisotropic viscoelastic saturated soils and raft foundation considering the stiffness contributions of the superstructure. Numerical examples are performed to study the influences of viscoelastic parameters, cross-anisotropic parameters, raft thickness and superstructure stiffness on the time-dependent behavior of the settlement and bending moment for the raft.

Prediction of triaxial drained creep behaviors of interactive marine-terrestrial deposit soils by fractal derivative

The mechanical properties of interactive marine-terrestrial (IMT) deposit soils differ from those of other deposits as a result of the complex sedimentary environments in which they are found. The creep behaviors of IMT deposits in Ningbo, China were studied via triaxial drained creep testing. The theory of fractal derivatives was then applied to develop a fractal merchant model, in which a fractal dashpot replaces the conventional Newtonian dashpot, to characterize the triaxial creep behaviors of IMT deposits. The model results indicate that Ningbo deposits demonstrate typical nonlinear creep behaviors. As the creep time and stress level increase, the creep process shows characteristics of transient creep attenuation and shear contraction. To validate the proposed fractal model, its predictive results were compared with the experimental results and those of conventional and fractional merchant models. It was found that the fractal merchant model results agree closely with the experimental results and that it was more accurate and efficient than the other models even though it applies the same number of parameters and has a simpler computational approach than the fractional merchant model.

Dual-channel environmental hotel supply chain network equilibrium decision under altruism preference and demand uncertainty

To study the influence of the altruistic preference of decision makers and the low-carbon preference of consumers on decision-making behaviour in all layers of a dual-channel environmental hotel supply chain, this paper constructs a dual-channel supply chain network equilibrium model comprising hotels, online travel agent(OTA) platforms and demand markets. Under the condition of uncertain demand from the merchant and agency mode perspectives, variational inequalities are used to describe the altruistic preference of each layer of agents and their mutual influence and the low-carbon preference of consumers. Then the equilibrium conditions of the system are obtained and the optimal decision-making results are obtained by using the improved projection gradient algorithm. Finally, the effectiveness of the model is verified through a numerical case analysis. It is found that the increase effort in carbon emission reduction has a significant impact on the profits of hotels and online travel agency platforms. The altruistic preferences of decision makers have different impacts on the supply chain under the merchant mode and the agency mode. When the altruistic preference for the OTA platform increases, the OTA platform model is more profitable than the merchant model. The deeper the degree of hotel altruism preference is, the greater the intra-hotel cooperation, which may lead to the rise of an Environmental Tourism Products and Service(ETP&S) volume in the direct selling market of hotels and make the profit of the OTA platform decrease slightly; however, the profit under the OTA platform is still higher than that under the merchant mode.

Constitutive Model of Lateral Unloading Creep of Soft Soil under Excess Pore Water Pressure

Presented in this paper is a study on the lateral unloading creep tests under different excess pore water pressures. The marine sedimentary soft soil in Shenzhen, China, was selected in this study. The results show that the excess pore water pressure plays a significant role in enhancing the unloading creep of soft soil. Higher excess pore water pressure brings more obvious creep deformation of soft soil and lower ultimate failure load. Meanwhile, the viscoelastic and the viscoplastic modulus of soft soil were found to exponentially decline with creep time. A modified merchant model and a combined model of the modified merchant model and plastic elements are used to simulate the viscoelastic and the viscoplastic deformation, respectively. Therefore, a lateral unloading creep model of soft soil is developed based on the modified merchant model. The accuracy and applicability of this model were verified through identifying the parameters in the model. Research results are of particular significance to the numerical simulation of underground space excavation in soft soil areas which considers the effects of excess pore water pressure.

Fractional non-axisymmetric consolidation of stratified cross-anisotropic visco-poroelastic media

This paper investigates the fractional non-axisymmetric consolidation of stratified cross-anisotropic visco-poroelastic media. Firstly, based on the Laplace–Hankel transform, the ordinary differential equations of cross-anisotropic poroelastic media are derived, which are extended to those of fractional visco-poroelastic media by introducing the fractional Merchant model and the elastic-viscoelastic correspondence principle. Then, the extended equations are solved by the extended precise integration method (PIM), and the proposed theory is compared with the results reported in the references. Finally, selected numerical examples are performed to investigate the effects of the order of fractional derivative, viscoelasticity, cross-anisotropy and stratification on the non-axisymmetric consolidation.

Effect of flax fiber orientation on machining behavior and surface finish of natural fiber reinforced polymer composites

Manufacturing processes of natural fiber reinforced polymer (NFRP) composites are becoming the interest of industrials and scientists because these eco-friendly materials are emerging in automotive and aerospace industries. In this context, machining processes of NFRP composites present significant issues related to the complex structure of natural fibers that need thorough tribological studies. This paper aims to explore the effect of natural fiber orientation on the machinability of NFRP composites using Merchant model in order to separate the shearing energy from the friction energy. Orthogonal cutting process is conducted on unidirectional flax fibers reinforced polypropylene composites by changing the fiber orientation from 0° to 90° with respect to the cutting direction. Iosipescu shear tests are also performed to determine the mechanical shear behavior in function of the fiber orientation. Results show the applicability of Merchant model on the machining analysis of NFRP composites by verifying the main model assumptions. The fiber orientation affects significantly the shearing and the friction energies that control the cutting behavior and the chip formation of the NFRP composite. The resulted machined surfaces are hence intimately related to the natural fiber orientation.

Investigation of a fractional derivative creep model of clay and its numerical implementation

The fractional calculus has been successfully applied to characterize the rheological property of elastic viscoplastic materials. However, soils were seldom involved in fractional derivative constitutive models, and the topic of triaxial creep tests is rarely discussed through fractional calculus. This study presents a fractional derivative model that describes the time-dependent behavior of Shanghai marine clay. The fractional derivative Merchant (FDM) model is established by introducing fractional element into the Merchant model. The comparison of the calculated values of the FDM model and the Merchant model shows that the FDM model can better describe the instant elastic deformation, attenuation creep and steady-state creep stages of the clay. The FDM model was implemented into a finite-element code in ABAQUS, which is used to simulate the creep tests. The simulations demonstrate that the development model has good ability to predict the time-dependent behavior of clay.