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This paper aims to propose a generalizable parameter calibration framework for discrete element method (DEM) and to develop the refined dynamic compaction DEM (RDCD) model for red-bed soft rocks (RBSR), which is used to investigate the contribution of tamping weight (W) and drop distance (H) to dynamic compaction quality control. Firstly, the linear model (LM) and the linear parallel bond model (LPBM) were selected to accurately represent the dynamic behavior of RBSR based on dynamic compaction characteristics. A generalizable calibration framework for LM and LPBM contact models was further proposed. Secondly, based on the calibration framework, a series of DEM simulations, parameters significance analysis, and physical tests were conducted to accurately calibrate the contact parameters of RBSR. Finally, the RDCD model for RBSR was developed, which was used to investigate the contribution of W and H to dynamic compaction quality control from a micro perspective. All results indicated that the proposed generalizable calibration framework could provide an accurate determination of RBSR contact parameters for dynamic compaction simulation. Specially, the lightweight inversion model for LPBM parameters was developed, enabling the rapid acquisition of contact parameters for RBSR. The LM parameters of RBSR were determined directly and indirectly, which could be directly applied to various RBSR. Moreover, the shockwaves generated by a heavier tamper with a lower drop distance had longer durations and larger propagation, enhancing the compactness of the overall specimen and generating larger and more uniformly distributed strong force chains. The dynamic compaction simulation results indicated that increasing the W could enhance dynamic compaction quality control. This paper contributes to the theoretical refinement of the contribution of W and H on-site dynamic compaction quality control. • A generalizable parameter calibration framework for discrete element method. • The refined dynamic compaction DEM model for red-bed soft rocks is developed. • The contribution of W and drop distance H to dynamic compaction is investigated. • The shockwaves generated by a heavier W have longer durations and propagation. [ABSTRACT FROM AUTHOR]

The use of temperature rise inhibitors (TRIs) holds significant promise in mitigating thermal cracking issues in modern concrete by controlling the precipitation of C-S-H gel, the main product of cement hydration. However, the complexity of their interaction with the non-classical nucleation process of C-S-H remains unclear. This study systematically investigated the influence of a sorbitol-based liquid-type temperature rise inhibitor (L-TRI) on the hydration kinetics of cement suspension using a combination of methods, including conductivity testing, pore solution analysis, and molecular dynamic simulations. It is revealed that the admixture-to-water ratio, rather than admixture-to-cement ratio, governs the effect of L-TRI on cement hydration. The disturbance of L-TRI molecules in the pore solution, mainly calcium complexation and water stabilization, plays a decisive role in inhibiting the secondary nucleation of C-S-H and decelerating the following growth. In contrast, L-TRI has a negligible influence on cement dissolution and the formation of C-S-H precursor. • Non-adsorbed L-TRI polymer impacts cement hydration through pore solution disturbance. • L-TRI barely affects cement dissolution and primary nucleation of C-S-H. • L-TRI inhibits the secondary nucleation of C-S-H by calcium complexation. • L-TRI decelerates the growth of C-S-H by calcium complexation and water stabilization. [ABSTRACT FROM AUTHOR]

During the cementing process, the oil-well cement (OWC) inevitably comes into contact with oil-based mud (OBM), which contaminates the OWC due to the incompatibility between OBM and the OWC. As a solution, hydrophilic surfactants can reduce interfacial tension and enhance the wetting compatibility of oil and water. Therefore, adding surfactants to the OWC is expected to alleviate contamination caused by OBM. In this study, a new strategy was proposed to combine non-ionic surfactants and anionic surfactants to form a composite surfactant (OP-S2), which overcomes the defect that excessive use of anionic surfactants deteriorates the performance of the OWC—showing great potential in adjusting the compatibility between OBM and the OWC and reducing cement contamination. The mechanism of contamination alleviation during the cementing process was elucidated by comparing the anticontamination properties of a single non-ionic surfactant (OP-S1) and OP-S2. In addition, molecular dynamics (MD) and dissipative particle dynamics (DPD) simulations were used to verify the mechanism of different types of surfactants in removing contamination further, providing theoretical guidance for future research on anti-contamination agents. [Display omitted] • Combining non-ionic and anionic surfactants to form a composite surfactant (OP-S2). • OP-S2 solves the defect that excessive single surfactant worsens OWC performance. • OP-S2 can meet the safety and quality requirements of ancient Wells. • Through MD and DPD simulation, the mechanism of surfactant removal was explored. [ABSTRACT FROM AUTHOR]

The granular materials were subjected to the principal stress rotation effect induced by traffic loads, wave loads, and earthquake loads in geotechnical engineering practice. In order to reveal the influence of principal stress rotation on the macro-micro dynamic characteristics, this study proposed a numerical simulation method modeling physical dynamic hollow cylinder tests. Taking the dynamic stress state induced by traffic loading as an example, the numerical test model of the dynamic hollow cylinder was conducted on the subgrade soil, and the influence of principal stress rotation on the macro-micro evolution of dynamic characteristics was analyzed.The results showed that the principal stress rotation accelerated the development of vertical accumulative plastic strain and particle displacement, which aggravated micro-structure destruction of granular material. Moreover, the increase of confining stress declined the variations of normal contact numbers in each direction, which resisted the shear stress induced by principal stress rotation. This study provided a novel method to investigate the macro-micro dynamic characteristics of granular materials subjected to principal stress rotation, which made up for the inability of physical hollow cylinder tests to study microscopic evolution. • The numerical method modeling the physical dynamic hollow cylinder test was established based on the DEM approach. • The proposed numerical method was validated compared the results from numerical and physical HCA test. • The evolutions of macro and micro dynamic characteristics were explored considering the principal stress rotation. [ABSTRACT FROM AUTHOR]

• An analytical WFD model developed by dynamic simulation of sheet flow. • The intervening factors of WFD evaluated and ranked based on field data. • Application of new analytical and empirical models for WFD prediction. • Validation test based on field data applied to verify the WFD models. Pavement drainage Evaluation is conducive to reduce hydroplaning risk. Empirical Water Film Depth (WFD) models are low accuracy and have limited application scope. This study develops an analytical WFD model by simulating the dynamic of sheet flow. Based on the field data of 10 test sites the analytical model and two empirical models are applied for WFD prediction. Refer to the field measured WFD, correlation tests are applied, and the findings include: the intervening factors on WFDs are ranked as follows rainfall intensity, pavement permeability, flow path length, flow path slope, and texture depth; the proposed analytical model is more accurate than Gallaway model and PAVDRN model. The significance is twofold. First, accumulated rainwater is involved in WFD estimation. Second, the hazardous ponding location is identified, so that pavement engineers can take remedial measures to reduce potential hydroplaning. [ABSTRACT FROM AUTHOR]

In order to analyze tire footprints in different conditions and calculate dynamic responses of asphalt pavement with vehicle braking, a tire-pavement coupling simulation system, which can use a viscoelastic constitutive model of asphalt concrete considering temperature dependence, is established. The user subroutine of the material model was programmed by the FORTRAN language, and viscoelastic parameters of the material model were recognized based on dynamic strain data of dynamic impact tests, whose validity was verified by using test data in the literature. The tire-pavement coupling simulation system was established to analyze tire footprints in static and dynamic conditions at different temperatures of asphalt concrete layer, whose calculation accuracy of the numerical simulation was verified. Based on measured temperature data at different depths of an actual pavement structure and the corresponding simulation model, thermal parameters of each layer in the pavement structure were recognized. Field distributions of the viscoelastic parameters in the asphalt concrete layer of the coupling simulation system were obtained by using the heat transfer analysis and the user subroutine. Average braking decelerations of trucks at a chosen intersection were calculated according to the investigation data. Based on the tire-pavement coupling simulation system, peak values of dynamic shear strain in the asphalt concrete layer at the intersection were calculated, which considered the coupling effect between axle loads and temperature fields. [ABSTRACT FROM AUTHOR]

• Theoretical models for calculating Cl− adsorption capacity are proposed from the perspectives of thermodynamics and dynamics. • pH and Ca2+ concentration are partners in determining the Cl− adsorption capacity and potential reversal of C-S-H gels. • Elevated temperature reduces Cl− adsorption by decreasing the activity of SiOH sites and the constraints of the gel on ions. Calcium silicate hydrate (C-S-H) gel, as the main hydration phase of cement, intensely influences the penetration and diffusion of chloride ions (Cl-) by interacting with multiple ions in diverse environments, affecting the durability of reinforced concrete. However, the adsorption mechanism and critical influence factor are indistinct. To reveal the micro/nano mechanism of the adsorption characteristics for Cl-, a comprehensive investigation was conducted, which included ion adsorption experiments, thermodynamic calculations, and molecular dynamic simulations. In contrast to the prevailing opinion that Ca2+ is a potential determining ion in cement paste systems. The results indicate that pH value and concentration of Ca2+ are the partner to determine the Cl- adsorption capacity and potential reversal of C-S-H gels. They are unable to function in isolation from each other. It should be mentioned that OH− is more important than Ca2+ for ions adsorption of C-S-H gels. Compared with Ca2+, the compensation of Na+ on the surface charge and the promotion of Cl- adsorption is limited. SO 4 2- competes for adsorption sites with Cl-, and forms Na-SO 4 clusters to inhibit the diffusion and adsorption of Cl-. Furthermore, elevated temperature not only promotes the thermal movement of ions but also decreases the Ca2+ concentration and pH value. Consequently, the activity of SiOH sites is lessened, and ions are subjected to weaker constraints by the gel, resulting in the decline of Cl- adsorption capacity. Moreover, theoretical models for calculating the amount of chloride adsorbed by the C-S-H gels are proposed from the perspectives of thermodynamics and dynamics, and the simulation results are in agreement with the experiment results. [ABSTRACT FROM AUTHOR]

• The virgin, fast-rate reaction, constant-rate reaction and full oxidation asphalt molecular models were established. • Asphalt oxidation kinetic aging process from molecular perspective was simulated. • Oxidation kinetic aging mechanism of asphalt were revealed. Asphalt oxidative aging leads to pavement to become harder and brittle, resulting in the complex cracking and other diseases. However, the microscopic causes of oxidative aging and these changes are not clear. It is meaningful to investigate the complex aging process of asphalt from virgin state to aged state from a microscopic perspective. Molecular dynamics (MD) simulation was used to investigate the oxidation kinetic aging process from the microscopic point of view. Asphalt binders were aged in the oven at five different aging times to simulate the oxidative aging. Saturates, asphaltene, resin, and aromatic (SARA) fraction weights of binders as well as carbonyls and sulfoxides at different aging states were determined using the four fractions separation test and Fourier Transform Infrared Spectroscopy (FTIR). The virgin, fast-rate reaction, constant-rate reaction and full oxidation asphalt molecular models were established corresponded to the proportions of SARA fractions, carbonyl index and sulfoxide index. These models were simulated to investigate the microscopic properties, and the oxidation kinetic aging mechanism of asphalt were revealed. [ABSTRACT FROM AUTHOR]

• Interface between geopolymer and PE fibre is simulated by molecular dynamic model. • The atomic interaction between the NASH gel and polyethene chains is computed. • H-bond, vdW force and mechanical interlocking at the interface are revealed. • Shear bonding strength between NASH gel and PE is predicted by pull-out simulation. • Effect of Si/Al ratio and water content on the bonding behaviour is studied. Cementitious materials suffer from their inherent brittleness, and thus much research has been devoted to circumventing this problem. A promising approach is incorporating polymeric fibre to enhance the ductility of cementitious materials. Therefore, fibre-reinforced geopolymer composite (FRGC) has attracted much attention due to its ultra-high ductility and environmentally friendly characteristics. The bonding between the fibre and matrix plays a critical role that impacts the FRGC's performance. However, the structure–property relationship of the composite is still unclear. In particular, the effect of matrix compositions, i.e., sodium aluminosilicate hydrated (NASH) gel, on the frictional bonding remains a mystery. In this paper, we employ molecular dynamics simulations to obtain a fundamental understanding of the interfacial interactions between NASH gels and polyethene (PE) fibre – a commonly found FRGC. The dynamic pull-out and the interfacial property characterisations are conducted for several NASH/PE models with different Si/Al ratios and internal moisture contents. Our results reveal that the adhesive bonding between the NASH and PE is influenced by the interfacial interaction and the mechanical interlocking between the two materials. The interfacial interaction energies between NASH and PE are dominated by the short-range van der Waals interactions and the hydrogen bonding between hydrogen atoms in the polyethene chains and oxygen atoms in the NASH. In addition, the Si/Al ratio can significantly impact the shear bonding strength between PE and NASH. Moreover, the degradation of the adhesive properties of NASH/PE composite strongly correlates to the internal moisture of the NASH. Thus, our work reveals the sources of frictional bonding between PE fibre and NASH gels, and relates the bonding performances with the Si/Al ratio and the internal moisture content of the matrix. Our results will provide valuable insights into the material design of FRGC and optimize their performances. [ABSTRACT FROM AUTHOR]

• A four-year-long observation of uneven rail deformation is performed in two HSR tunnels. • The predominant wavelength and amplitude of rail deformation in tunnel are 3–30 m and 2–10 mm, respectively. • The heave transfer within track structure exhibits more significantly on wavelength than on amplitude. • Speed raising has strong effects on the magnitude and location of wheel-rail contact force. • The risk of derailment and passenger comfort is more sensitive to short- and long-wavelength floor heave, respectively. Floor heave is a huge threat to the safe operation of high-speed trains in tunnels. However, rare research recognizes the characteristics of the rail irregularity caused by tunnel floor heave and the corresponding running risk of high-speed trains. In this paper, uneven rail profiles observed within four years in two HSR tunnels are used to investigate the temporal variation and spatial distribution of tunnel floor heave. The predominant wavelength and amplitude of the heave profile are determined. Hypothetic floor heave profiles with a wide range of wavelength and amplitude are used as the input in the simulation of the dynamic response of a VRT (vehicle-rail-track) system. Based on the simulation, the transfer laws for the wavelength and amplitude of heave within the track structure are revealed. The wheel-rail contact force, the wheel load reduction rate, and the sperling factor under various floor heave profiles are calculated. The floor heave profile that may lead to a high risk of derailment and low passenger comfort is presented for two train speeds. The research reveals that the predominant range of the wavelength for the rail heave in the tunnel is from 3 m to 30 m, and that of the amplitude is 2 mm to 10 mm. The heave transfer law within the track structure is strongly affected by both the wavelength and amplitude of the floor heave profile. The deformation of the rail varies more significantly on wavelength than on amplitude. Speed raising strongly influences the wheel-rail contact force, the wheel load reduction rate, and the sperling factor. The passenger comfort is more sensitive to longer-wavelength floor heave, whereas the risk of the derailment is more sensitive to shorter-wavelength floor heave. [ABSTRACT FROM AUTHOR]

[Display omitted] • Investigating molecular failure mechanics of NF with cement using MD simulation. • Microscale characterization of the cement paste with NF. • A framework connecting the properties of cement paste with NF from multiple scales. Using nanofillers, such as nano-Fe 2 O 3 , nano-Al 2 O 3 and nano-SiO 2 , in the design of ultra-high-performance cementitious composites is widely practised, but there is a lack of quantitative understanding of the role these nanofillers play at molecular or micro levels. In the present study, we proposed a framework to offer an insight into molecular failure mechanics, microscale characterisation and the mechanical performance of cement with nanofillers. Results from the multiple-scale investigation showed good consistency and supported each other. Reactive molecular dynamic simulations indicated that the mechanics of molecular failure between nanofillers and cement primarily depends on their interfacial bonding, transitioning from adhesive failure at the interface to cohesive failure within adjacent cement hydrates. Results from microscale characterization further confirmed that mineral nanofillers in cement strengthened the surrounding cement hydrates, generating around 63.64–161.97% increase in high-density hydrates, while also expediting the reduced the porosity from 17.62% to 39.51% relative to reference samples. Consequently, the mechanical properties of the cement paste were improved. These findings quantify the role of nanofillers in cement systems and provide fundamental understanding of key material design parameters for mechanical property enhancement of cementitious nanocomposites. [ABSTRACT FROM AUTHOR]

• The in-situ dynamic measurements of the track structure in an operating subway line were conducted; • The multi-objective functions according to the simulated and measured results were proposed; • The sensitivity analysis based on the Latin Hypercube Sampling (LHS) was designed and implemented; • The model updating process based on the multi-island genetic algorithm (MIGA) was devised and performed; • Results indicate that the proposed method is effective and feasible. With the rapid development of subway transportation, it has brought great convenience to us, but the induced vibration has seriously influenced our daily life. The simulation models are the major approach to investigate this problem. However, due to the discreteness and randomness of the physical parameters of various materials and inappropriate simplifications of the finite element (FE) model, the simulated results cannot reflect the actual dynamic responses accurately. To solve this issue, we carried out systematic investigations as follows: (1) conducting in-situ dynamic measurements of the track structure in an operating subway line; (2) establishing a simulation model of the vehicle-track coupled system; (3) proposing the multi-objective functions according to the simulated and measured results; (4) designing and implementing the sensitivity analysis based on the Latin Hypercube Sampling (LHS); (5) devising and performing the model updating process based on the multi-island genetic algorithm (MIGA). The results reveal that the updated model can simulate the dynamic responses accurately, and the simulation results have an excellent agreement with the in-situ measurements. Overall, the developed method in this work can obviously improve the accuracy of the dynamic simulation of the track structure and provide a way for the model updating and vibration analysis of the vehicle-track coupled system. [ABSTRACT FROM AUTHOR]

• Increasing the preheating temperature and diffusion time of rejuvenator can enhance its diffusion. • The 110℃ rejuvenator preheating temperature is recommended to improve diffusion effect. • The 3-hour recycled mixture's curing time is recommended to improve its performance. The recycled hot mix asphalt mixture performance is improved by a rejuvenator with good diffusion ability. This paper investigates the rejuvenator-aged asphalt diffusion and its influencing factors, including the rejuvenator's preheating temperature and curing process of recycled mixtures. A molecular dynamic simulation of the diffusion process between rejuvenator and aged asphalt is performed. Its results are then validated by a gel permeation chromatography test. Laboratory tests are also employed to evaluate these two factors' influence on the recycled mixture's performance on a macroscale. Simulated and experimental results strongly indicate that a proper combination of rejuvenator preheating and recycled mixture curing improves the rejuvenator diffusion ability and the recycled mixture performance. Following this, the 110℃ preheating temperature of rejuvenator and the 3-hour curing time after completing the mixing process of the hot plant-mix asphalt mixture are recommended based on the above results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nano-scale moisture migration model in the asphalt-aggregate interface is built for the first time. • The nano-scale moisture distribution in asphalt-aggregate interface was investigated. • Effects of aggregate type, humidity and hydraulic pressure on moisture diffusion in asphalt-aggregate interface are studied. Presence of moisture can weaken the asphalt-aggregate bond and result in aggregate stripping and moisture damage in asphalt mixture. This study investigates how the moisture affects the asphalt-aggregate bond and simulates moisture distribution of nano-scale in asphalt-aggregate interface. Effects of aggregate type (basalt, dolomite and limestone minerals), humidity and hydraulic pressure on moisture diffusion in asphalt-aggregate interface are studied. Diffusion coefficient (D), radial distribution function (RDF), contact angle (CA), free volume (FV) are calculated through molecular dynamic simulations. Polarizability of moisture in the asphalt-aggregate interface was measured using density function theory (DFT). Nano-scale moisture migration model in the asphalt-aggregate interface is built for the first time. The results show that D depends more on the hydraulic pressure than humidity and aggregate type which represents the significance of hydraulic pressure on the moisture diffusion. In addition, the aggregate type has significant effects on RDF, CA and FV. DFT results indicate that polarizability of moisture changes for different types of aggregate and hydraulic pressure values. In the asphalt-water-aggregate interface, the asphalt competitively interacts with moisture and ions from minerals through intermolecular forces. [ABSTRACT FROM AUTHOR]

• A dynamic climate change impact evaluation framework is proposed. • Bamboo bio-concrete is a good climate change mitigation and adaptation alternative. • Bamboo bio-concrete presents a reliable carbon-thermal energy solution. • Bamboo bio-concrete provides a promising alternative for developing countries. This study aims to present a framework to quantify the climate change impact during the buildings' life cycle. The proposed framework is tested on a bamboo bio-concrete (BBC) building and compared with conventional constructive systems, in a Brazilian housing project considering six cities using Dynamic Life Cycle Assessment (DLCA) and thermal energy simulation. The increase of BBC in the building envelope, from 10 cm to 20 cm, leads to the improvement of carbon stock and reduces operational carbon. The BBC can be considered a potential alternative for climate change mitigation and adaptation and developed where bamboo is an available source. [ABSTRACT FROM AUTHOR]

• Knowledge of ancient materials is essential for conservation of the built heritage. • Characterization of the ancient material leads to the best eco-renovation solution. • Determination of the properties of ancient materials to enrich databases. • The identified properties help to refine current dynamic simulation models. • The fired brick material may be a good element for dating ancient buildings. In order to complete the in situ identification of the "demonstrator" (or model) buildings chosen in the framework of the European Regional Project SUDOE ENERPAT for the eco-renovation of heritage residential habitat in the historic centres of Cahors (France), Porto (Portugal) and Vitoria (Spain), a campaign of characterizations was carried out on the materials constituting the initial envelope. The results of the main measured material properties bricks, stones and lime plaster (taken from the envelope of the building in Cahors) are presented. The emphasis is on hygrothermal characterization. Structural characterizations are addressed as well as data on physicochemical and mechanical aspects. The results on the variations of the properties identified are discussed. The age, mineralogical composition, manufacturing process, moisture content and prevailing environmental conditions are all parameters that cause these variations and contribute to the state of preservation of ancient materials. The identified properties of the materials will serve as inputs to the software and models intended to characterize the behaviour of envelopes of ancient buildings. The first findings can help in the choices of treatment for these ancient materials. The proposed eco-renovation solutions can be appropriate for the preservation, of both the architectural heritage and the historic centres. [ABSTRACT FROM AUTHOR]

• Physicochemical interaction ability was evaluated by adsorbed film thickness. • Higher temperature and lower loading frequency led to stronger physicochemical interaction. • Polar components were distributed near the surface of silica particle to form adsorbed film. • Non-polar molecules moved away from silica particle due to temperature elevating. • More and more polar molecules were adsorbed by silica particle with temperature increasing. Asphalt mastic consists of asphalt binder and mineral filler and the physicochemical interaction between two them plays significant role in the service performance of asphalt concrete, which can be directly evaluated by their interfacial adsorbed film thickness. This study investigated the effects of temperature, loading frequency and other factors on the adsorbed film thickness. The results showed that with the increase of temperature and the decrease of loading frequency, the adsorbed film thickness between asphalt binder and mineral filler became thicker. Additionally, the addition of SBS modifier into base asphalt led to the stronger interaction ability with mineral filler at high temperature (i.e., low frequency) region. Compared with inert mineral filler, the adsorbed film thickness between active filler and asphalt binder was thicker, which provided insight into asphalt mastic design. Furthermore, the investigation of physicochemical interaction mechanism between asphalt and filler paves the way to understand the effect of these factors on interaction ability, which was analyzed at the molecular and atomistic scale through molecular dynamic simulation in this study. The asphalt mastic molecular model was also used to simulate temperature how to influence the adsorbed film thickness. The findings showed that compared with non-polar molecules of asphalt binder, the adsorption force between mineral filler particles and polar molecules was stronger. Asphalt non-polar components moved away from the surface of filler particle with the temperature increasing, while more and more polar components were adsorbed by filler particle, which caused thicker adsorbed film thickness and thus stronger interaction ability between mineral filler and asphalt binder. [ABSTRACT FROM AUTHOR]

• Molecular dynamics simulation of the newly introduced model of N-A-S-H geopolymer. • Using of N-A-S-H structure model validated by experimental results of previous literatures for modulus of elasticity. • Extracting much more realistic outcomes relative to the results of simulations performed in the past. Geopolymer as a new type of alkaline cement with low CaO is produced by the synthesis of aluminosilicate materials with an alkaline solution. The identical structure of geopolymers is still unclear, although a number of structures have been considered. N-A-S-H compound as one of these introduced structures consists of different molecule components. The latest N-A-S-H model for geopolymers includes structural aluminosilicate molecules with various motifs of charge balancing of Q 4 (4 A l) S i seems to be appropriate for molecular dynamic simulations. Since the optimum ratio of Si/Al = 2 is reported by different researchers, in this paper the N-A-S-H model is modified by reconsidering this ratio for molecular dynamics simulations to obtain its modulus of elasticity. Simulation parameters were chosen based on the findings of the past literature review. In order to consider the randomness of the proposed amorphous structure of N-A-S-H several simulations were conducted to find the mean value of the modulus of elasticity. The modulus of elasticity was calculated by an existing stress-strain script in the Material Studio® software. The simulation results showed good agreements with the existing experimental ones. This finding proves that the proposed modified N-A-S-H model is capable of being considered for further research and investigations. [ABSTRACT FROM AUTHOR]