scholarly journals A Trans-Scale Young’ Modulus Calculation Model of ITZ Based on Void Shape Randomness and Calcium Hydroxide Enrichment

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Junqing Liu ◽  
Fan Zuo ◽  
Chao Liu

The randomness of void shape and enrichment of calcium hydroxide are significant in interfacial transition zone (ITZ) of concrete; however, current theoretical models of ITZ do not include these features. In this article, ITZ was regarded as a three-phase composite material, and the pore morphological parameters were defined according to the characteristics of microscopic pores, and the corresponding random distribution function was constructed. The calcium hydroxide enrichment factor was introduced, and a cross-scale ITZ Young’s modulus calculation model was established in combination with the Mori–Tanaka method. The reliability of the proposed model in this paper was verified through comparison to experimental results in a reference.

2014 ◽  
Vol 6 (1) ◽  
pp. 1032-1035 ◽  
Author(s):  
Ramzi Suleiman

The research on quasi-luminal neutrinos has sparked several experimental studies for testing the "speed of light limit" hypothesis. Until today, the overall evidence favors the "null" hypothesis, stating that there is no significant difference between the observed velocities of light and neutrinos. Despite numerous theoretical models proposed to explain the neutrinos behavior, no attempt has been undertaken to predict the experimentally produced results. This paper presents a simple novel extension of Newton's mechanics to the domain of relativistic velocities. For a typical neutrino-velocity experiment, the proposed model is utilized to derive a general expression for . Comparison of the model's prediction with results of six neutrino-velocity experiments, conducted by five collaborations, reveals that the model predicts all the reported results with striking accuracy. Because in the proposed model, the direction of the neutrino flight matters, the model's impressive success in accounting for all the tested data, indicates a complete collapse of the Lorentz symmetry principle in situation involving quasi-luminal particles, moving in two opposite directions. This conclusion is support by previous findings, showing that an identical Sagnac effect to the one documented for radial motion, occurs also in linear motion.


2014 ◽  
Vol 698 ◽  
pp. 694-698 ◽  
Author(s):  
Dmitry I. Bliznyuk ◽  
Pavel Y. Bannykh ◽  
Alexandra I. Khalyasmaa

The paper is devoted to the problem of power flow calculation and steady state analysis methods adaptation for four-phase electrical grids. These methods are based on developed models of four-phase power lines and phase convering transformers. The basis of research is nodal voltages equations for three-phase, four-phase and mixed (combined by three-and four-phase elements) grids. Algorithm of four-phfase elements parameters automized adaptation for power flow calculation model of "RastrWin" software have been developed.


2020 ◽  
Vol 5 (3) ◽  
pp. 80
Author(s):  
Mei Ge ◽  
Zhongping Deng ◽  
Jing He

<p>The purpose of this paper is empirically to examine two theoretical models in the context of social electronic commerce (s-commerce). The study tries to extend TAM and UTAUT model with trust to explain consumer behavior in the acceptance of s-commerce on WeChat platform which is the Chinese largest social platform. Through an online survey, 501 valid respondents were collected. A Partial Least Squares (PLS) analysis was used to conduct the proposed model and hypothesis testing with TAM and UTAUT models. The results revealed that trust is the most significant factor affecting behavioral intention and the second significant factor is effort expectancy, then social influence and performance expectancy. The integration of trust factor into the UTAUT model best interprets the adoption of s-commerce among the pure TAM and UTAUT models and extended models with trust. It will provide guidance for marketers and professionals, especially in China.</p>


2013 ◽  
Vol 325-326 ◽  
pp. 519-524
Author(s):  
Lian Liu ◽  
Qiong Lin Li ◽  
Hui Jin Liu ◽  
Xue Cui ◽  
Lei Zou

Beginning with characterizing the nonlinearities of transformer, this paper uses the J-A model to represent the hysteresis of iron core, and fits the model in calculating exciting current. Compared with the other methods, such as polynomial and describing function method, J-A model is more capable in representing nonlinearity, so the calculated current would be more accurate. Then, after analyzing Maxwell equations that meet certain boundary conditions, the paper considers comprehensively the effects of skin and proximity, and then obtains the computing way of ac resistance under harmonics. At last, based on the mentioned results, paper proposes a set of three-phase transformer model which could calculate harmonic losses. The proposed model is a kind of combined time-and frequency-domain model that possesses good convergence. The introduced example has verified the correctness and effectiveness of the model which absolutely suits the engineering applications.


Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2923
Author(s):  
Matias Berg ◽  
Tomi Roinila

Grid-connected and grid-forming inverters play essential roles in the utilization of renewable energy. One problem of such a converter system is the voltage deviations in the DC-link between the source and the inverter that can disrupt the inverter output voltage. A common method to prevent these voltage deviations is to apply an input-voltage feedforward control. However, the feedforward control has detrimental effects on the inverter dynamics. It is shown that the effect of the feedforward in the input-to-output dynamics is not ideal due to the delay in the digital control system. The delay affects the input-to-output dynamics at high frequencies, and only a minor improvement can be achieved by low-pass filtering the feedforward control signal. Furthermore, the feedforward control can remarkably affect the inverter input admittance, and therefore, impedance-based stability problems may arise at the DC interface. This paper proposes a method based on linearization and extra element theorem to model the effect of the feedforward control in the inverter dynamics. Experimental measurements are shown to demonstrate the effectiveness of the proposed model.


2020 ◽  
Vol 223 (2) ◽  
pp. 993-1006
Author(s):  
Luong Duy Thanh ◽  
Damien Jougnot ◽  
Phan Van Do ◽  
Nguyen Van Nghia A ◽  
Vu Phi Tuyen ◽  
...  

SUMMARY In reservoir and environmental studies, the geological material characterization is often done by measuring its electrical conductivity. Its main interest is due to its sensitivity to physical properties of porous media (i.e. structure, water content, or fluid composition). Its quantitative use therefore depends on the efficiency of the theoretical models to link them. In this study, we develop a new physically based model that takes into account the surface conductivity for estimating electrical conductivity of porous media under partially saturated conditions. The proposed model is expressed in terms of electrical conductivity of the pore fluid, water saturation, critical water saturation and microstructural parameters such as the minimum and maximum pore/capillary radii, the pore fractal dimension, the tortuosity fractal dimension and the porosity. Factors influencing the electrical conductivity in porous media are also analysed. From the proposed model, we obtain an expression for the relative electrical conductivity that is consistent with other models in literature. The model predictions are successfully compared with published experimental data for different types of porous media. The new physically based model for electrical conductivity opens up new possibilities to characterize porous media under partially saturated conditions with geoelectrical and electromagnetic techniques.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Andres Soto ◽  
Shanavas Shajahan ◽  
Roberto Acevedo

AbstractThis article aims to develop a generalized model calculation model to be applicable to the general theory of interaction potentials with reference to the stoichiometric elpasolite type crystals. In this study, we have chosen to report both a theoretical model and a calculation strategy to undertake semi empirical calculations of thermodynamic properties, such as reticular energies and heats of formation for the series of systems such as: Cs2KLnCl6. We have also carried out quite a number of calculations for a variety of systems such as: Cs2NaLnF6, Cs2NaLnCl6, Cs2NaLnBr6, Rb2NaLnF6and Cs2KLnF6 in the Fm3m space group since we aim to check the strengths and weaknesses of our model calculations. We have analyzed a substantial number of approximate theoretical models and have carried a formidable amount of computing simulations to estimate the reticular energies and the corresponding heat of formation for these type of crystal using a semi empirical model. We made use of the thermodynamic cycles of Born-Haber so as to get a broad view with reference to the accuracy of our semi empirical theoretical models. The problem itself is quite challenging since we have focused our attention upon trivalent lanthanide ions $$L{n}^{+3}$$Ln+3 in the first inner transition series of the chemical elements: (Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). There are a significant amount of outstanding research works published in the literature with reference to structural analysis, one photon spectroscopy, vibrionic intensity model calculations and generalized models to deal with these kind of complex crystals. The calculated energy values associated with these observables seems to be most reasonable, and these follow the expected trends, as may be expected on both theoretical and experimental grounds. Both, the advantages and disadvantages of the current model calculations, have been tested against other previous calculations performed for this type of complex systems. It is of a paramount importance, the results obtained and reported in this article with regards to convergence tests as well as some master equations derived to account for the various contributions to the total energy. The Born-Mayer-Buckingham potential is carefully examined with reference to these lanthanide type crystals Cs2KLnCl6. Finally but not at last, the most likely sources for improvement are carefully discussed in this work. We strongly believe that there is enough room for improvement and have therefore initiated a new research program of activities tackling systems of well-known optical and structural properties.


2014 ◽  
Vol 11 (96) ◽  
pp. 20140089 ◽  
Author(s):  
Quan-Xing Liu ◽  
Ellen J. Weerman ◽  
Rohit Gupta ◽  
Peter M. J. Herman ◽  
Han Olff ◽  
...  

Theoretical models highlight that spatially self-organized patterns can have important emergent effects on the functioning of ecosystems, for instance by increasing productivity and affecting the vulnerability to catastrophic shifts. However, most theoretical studies presume idealized homogeneous conditions, which are rarely met in real ecosystems. Using self-organized mussel beds as a case study, we reveal that spatial heterogeneity, resulting from the large-scale effects of mussel beds on their environment, significantly alters the emergent properties predicted by idealized self-organization models that assume homogeneous conditions. The proposed model explicitly considers that the suspended algae, the prime food for the mussels, are supplied by water flow from the seaward boundary of the bed, which causes in combination with consumption a gradual depletion of algae over the simulated domain. Predictions of the model are consistent with properties of natural mussel patterns observed in the field, featuring a decline in mussel biomass and a change in patterning. Model analyses reveal a fundamental change in ecosystem functioning when this self-induced algal depletion gradient is included in the model. First, no enhancement of secondary productivity of the mussels comparing with non-patterns states is predicted, irrespective of parameter setting; the equilibrium amount of mussels is entirely set by the input of algae. Second, alternate stable states, potentially present in the original (no algal gradient) model, are absent when gradual depletion of algae in the overflowing water layer is allowed. Our findings stress the importance of including sufficiently realistic environmental conditions when assessing the emergent properties of self-organized ecosystems.


2003 ◽  
Vol 86 (12) ◽  
pp. 2162-2166 ◽  
Author(s):  
Valeri S. Harutyunyan ◽  
Eduward S. Abovyan ◽  
Paulo J. M. Monteiro ◽  
Vahram P. Mkrtchyan ◽  
Minas K. Balyan ◽  
...  

Fractals ◽  
2010 ◽  
Vol 18 (01) ◽  
pp. 53-64 ◽  
Author(s):  
MAOFEI MEI ◽  
BOMING YU ◽  
JIANCHAO CAI ◽  
LIANG LUO

The size distributions of solid particles and pores in porous media are approximately hierarchical and statistically fractals. In this paper, a model for single-phase fractal media is constructed, and the analytical expressions for area, fractal dimension and distribution function for solid particles are derived. The distribution function of solid particles obtained from the proposed model is in good agreement with available experimental data. Then, a model for approximate two-phase fractal media is developed. Good agreement is found between the predicted fractal dimensions for pore space from the two-phase fractal medium model and the existing measured data. A model for approximate three-phase fractal media is also presented by extending the obtained two-phase model.


Sign in / Sign up

Export Citation Format

Share Document