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Purpose – Recently, acoustic characteristics of the indoor space are more important due to society economic development needs. Meanwhile, container houses are gradually widely used in quite a lot of space applications for sustainable and easy use features. Those are still need to remain the pleasant and quiet sound environment. The paper aims to discuss these issues. Design/methodology/approach – In this paper, commercial software Ecotect Analysis is used to calculate the sound characteristics of container house. And the decorated material of this small indoor space is redesigned for obtaining the acoustic comfort under the optimal reverberation time. First, three-dimensional model of the container house is constructed by default tools of software. The indoor acoustic characteristics for various design conditions can be obtained by the simulation process. Findings – By comparing the experiment and simulation results, excellent agreement is represented to verify the feasibility of the software. Second, the original container house is caused by reverberation time distribution in 140-315 ms. After selecting the interior material, its reverberation time distribution in 160-680 ms. Originality/value – Following the design process, the spatial designers can assess the indoor acoustic characteristics in concept design stage and good acoustic comfort environment of building is derived. Meanwhile, improve the quality of living and construction costs reducing can be implemented. [ABSTRACT FROM AUTHOR]

Ferrogels, i.e., magnetic nanoparticles immersed into a swollen polymer gel, are materials which combine the magnetic properties of a ferrofluid with the elastic properties of a hydrogel. This makes it possible to control their shape and elasticity by means of external magnetic fields. Magnetic gels are therefore considered for medical and technical applications such as actuation and drug delivery systems. In this paper, we focus on a special class of magnetic gels in which the magnetic nanoparticles act as the cross-linkers of the polymer network. Experimentally this is achieved by functionalizing the nanoparticles' surface such that the polymers can covalently bind to it. In this way, a coupling between the orientation of the nanoparticles and the polymer matrix is created. When an external magnetic field is applied to such a system, the magnetic particles align to the field, and due to the coupling between the nanoparticles' orientation and the gel matrix, a strain is exerted on the polymers. This leads to a shrinking of the gel as a whole. In this paper, we explain how to extend a two-dimensional simulation model for such a system (Soft Matter 8 (2012) 9923 [18] ) to three dimensions. We will show that, while an isotropic deformation was observed in the two-dimensional case, in three dimensions the gel shrinks anisotropically. This is due to the fact that orientational fluctuations of the nanoparticles are hindered in the direction perpendicular to an external magnetic field. [ABSTRACT FROM AUTHOR]

Based on the finite-time stability theory, this paper deals with finite-time synchronization for a class of fuzzy cellular neural networks with time-varying coefficients and proportional delays. Using differential inequality techniques and the analysis approach, we derive some new and useful sufficient conditions of finite-time synchronization for the addressed systems. Finally, an illustrative example with its numerical simulations is given to show the effectiveness of main results. [ABSTRACT FROM AUTHOR]

This paper aims to study the dynamical behaviours of an SIQR epidemiological model. Positivity and boundedness of the system are discussed. Stability analysis of the equilibrium points is presented. Numerical simulations are carried out to validate our analytical findings. Implications of our analytical and numerical ûndings are discussed critically. [ABSTRACT FROM AUTHOR]

How to develop efficient numerical schemes while preserving energy stability at the discrete level is challenging for the three-component Cahn-Hilliard phase-field model. In this paper, we develop a set of first- and second-order temporal approximation schemes based on a novel 'Invariant Energy Quadratization' approach, where all nonlinear terms are treated semi-explicitly. Consequently, the resulting numerical schemes lead to well-posed linear systems with a linear symmetric, positive definite at each time step. We prove that the developed schemes are unconditionally energy stable and present various 2D and 3D numerical simulations to demonstrate the stability and the accuracy of the schemes. [ABSTRACT FROM AUTHOR]

Discrete hard fault is always tested in existing node selection methods for analog circuit diagnosis. Actually, analog component parameter changes continuously and output node voltages distribute in a continuous voltage interval. In this paper, an novel test node selection method is proposed for continuous parameter shifting (CPS) fault. Firstly, CPS faults are sampled by parameter scan simulation in a single test frequency. Collected node voltages are seen as a data set in a statistical distribution. Secondly, ambiguous faults are identified according to the independent distributions of all CPS faults. The independence of CPS fault sample is deduced by Kruskal-Wallis non-parametric testing. Then, new fault dictionaries are generated for each test node according to ambiguous interval. The proposed fault dictionary represents the mutual independence of each pair of CPS faults. Finally, as fault dictionaries are considered as connected graphs, the optimal test nodes are selected based on an improved depth first search (DFS) algorithm. The effectiveness of method is verified by testing linear and nonlinear circuits. [ABSTRACT FROM AUTHOR]

Charge accumulation on a solid insulator surface is one of the critical factors for the development of dc gas-insulated equipment since it will lead to the overstress of polymeric insulation due to local field distortion and enhancement. Therefore, it is important to study the charge accumulation phenomenon on spacer surface under dc field. For decades, researchers have made tremendous progress on this subject by measurement and simulation. However, measurement results are quite different by different researchers due to various electrode configurations and experimental conditions. Further, most researchers use potential to represent charge density, which is not rigorous in that many charge density distribution details are hidden behind the potential. As for pure numerical simulation, reports are rather academic and sometimes cannot accord with the real fact. In this paper, attempts are made to characterize the charge accumulation patterns on spacer surface in HVDC gas-insulated system. Surface charge distributions on a model GIL spacer in 0.1 MPa air under DC voltage are obtained by an advanced measurement method, from which the dominant uniform charging pattern and random charge speckles are separated. Mechanism responsible for the dominant uniform charging pattern is discussed with the aid of a simulation model. Results indicate that, in a well-cleaned system, the electric current through the spacer bulk is the principal factor, but gas conduction is not negligible due to some inevitable ion sources. Highly localized pockets of charge are also observed, which are referred to as speckles. They may originate from micro discharges due to tiny metal particles on the spacer surface or microscopic protrusions on the electrodes. [ABSTRACT FROM PUBLISHER]

Spatial simulations are a valuable tool in understanding dynamic spatial processes. In developing these simulations, it is often required to make decisions about how to represent features in the environment and how events unfold in time. These spatial and temporal choices have been shown to significantly alter model outcomes, yet their interaction is less well understood. In this paper, we make use of a simple group foraging model and systematically vary how features are represented (cell size of the landscape) as well as how events unfold in time (order in which foragers take action) to better understand their interaction. Our results show similar nonlinear responses to changes in spatial representation found in the literature, and an effect of the order in which agents were processed. There was also a clear interaction between how features are represented and how events unfold in time, where, under certain environmental representations results were found to be more sensitive to the order in which individuals were processed. Furthermore, the effects of feature representation, scheduling of agents, and their interaction were all found to be influenced by the heterogeneity of the spatial surface (food), suggesting that the statistical properties of the underlying spatial variable will additionally play a role. We suggest that navigating these interactions can be facilitated through a better understanding of how these choices affect the decision landscape(s) on which agents operate. Specifically, how changes to representation affect aggregation and resolution of the decision surface, and thereby the degree to which agents interact directly or indirectly. We suggest that the challenges of dealing with spatial representation, scheduling, and their interaction, while building models could also present an opportunity. As explicitly including alternate representations and scheduling choices during model selection can aid in identifying optimal agent–environment representations. Potentially leading to improved insights into the relationships between spatial processes and the environments in which they occur. [ABSTRACT FROM AUTHOR]

Utilization of hydraulic-fracturing technology is dramatically increasing in exploitation of natural gas extraction. However the prediction of the configuration of propagated hydraulic fracture is extremely challenging. This paper presents a numerical method of obtaining the configuration of the propagated hydraulic fracture into discrete natural fracture network system. The method is developed on the basis of weighted fracture which is derived in combination of Dijkstra's algorithm energy theory and vector method. Numerical results along with experimental data demonstrated that proposed method is capable of predicting the propagated hydraulic fracture configuration reasonably with high computation efficiency. Sensitivity analysis reveals a number of interesting observation results: the shortest path weight value decreases with increasing of fracture density and length, and increases with increasing of the angle between fractures to the maximum principal stress direction. Our method is helpful for evaluating the complexity of the discrete fracture network, to obtain the extension direction of the fracture. [ABSTRACT FROM AUTHOR]

Simulation of the nonlinear mechanical response of materials with explicit representation of microstructural features is extremely challenging. These models typically involve a very large number of degrees of freedom, and are prone to convergence difficulties when searching for roots to nonlinear equilibrium equations. We focus on an idealized material model that is motivated by the microstructure of synthetic nacre: individual ‘bricks’ (representing ceramic platelets) interact through nonlinear cohesive springs (representing a small volume fraction of polymer that bonds the platelets). The model simulates composite fracture through rupture of the cohesive springs. The problem is cast in terms of energy minimization and is essentially described by ‘nearest neighbor’ interactions. The principal focus of this paper is to illustrate the computational gains achievable by the strategic marriage of robust, global Monte Carlo minimization algorithms to the graphics processing unit architecture, and to describe how they were realized on the Nvidia GPU. Results comparing the computation times for graphics processing unit and central processing unit implementations demonstrate that a new adaptive version of the simulated annealing algorithm yields a speedup of approximately 5 times, whereas the graphics processing unit implementation yields a speed-up of about 16 times over conventional four-core central processing unit implementations. The resulting speed enhancement for adaptive graphics processing unit minimization of a factor of 80 enables a far broader range of simulations than has previously been possible. Simulations involving as many as 300,000 bricks can be performed in hours, as compared to weeks required by central processing unit implementation. Many aspects of this approach are translatable to other physical problems involving energy minimization in systems with large numbers of degrees of freedom. [ABSTRACT FROM AUTHOR]

Screens are an important production unit in crushing plants. The performance of the screen is essential to the performance of the crushing plant. In this paper a mechanistic model of a banana screen is described and a novel model for screen deck configuration is presented. The developed model can be used for optimization of a screen so that it has the best possible performance with respect to different feeding conditions, in order to obtain a desired separation. The simulation results were compared to full scale test data and the conclusions from this comparison is that the screen model needs further parameters to handle the necessary screen deck configuration. An initial static model was derived to explain how the screen deck configuration will affect the screen efficiency. The modification of the screen deck parameters resulted in a better correlation both regarding size distribution and predicted capacity. [ABSTRACT FROM AUTHOR]

In this paper, we present the first computer simulation of methanol exchange dynamics between the first and second solvation shells around different cations and anions. After water, methanol is the most frequently used solvent for ions. Methanol has different structural and dynamical properties than water, so its ion solvation process is different. To this end, we performed molecular dynamics simulations using polarizable potential models to describe methanol-methanol and ion-methanol interactions. In particular, we computed methanol exchange rates by employing the transition state theory, the Impey-Madden-McDonald method, the reactive flux approach, and the Grote-Hynes theory. We observed that methanol exchange occurs at a nanosecond time scale for Na+ and at a picosecond time scale for Cs+, Cl-, and I-. We also observed a trend in which, for like charges, the exchange rate is slower for smaller ions because they are more strongly bound to methanol. [ABSTRACT FROM AUTHOR]

The paper focuses on a nonlinear model to represent the mechanical behaviour of a mix coil spring - rubber used in the secondary suspension of passenger rail vehicles. The principle of the model relies on overlapping of the forces corresponding to three components - the elastic component, the viscous component and the dry friction component. The model has two sources on non-linearity, in the elastic force and the friction force, respectively. The main attributes of the model are made visible by its response to an imposed displacement-type harmonic excitation. The results thus obtained from the applications of numerical simulation show a series of basic properties of the model, namely the dependence on amplitude and the excitation frequency of the model response, as well as of its stiffness and damping. [ABSTRACT FROM AUTHOR]

Numerical simulation of shielding effectiveness (SE) of a perforated shielding enclosure is carried out, using the finite element method (FEM). Possibilities of model definitions and differences between 2D and 3D models are discussed. An important part of any simulation is verification of the model results-here the simulation result are verified in terms of convergence of the model in dependence on the degrees of freedom (DOF) and by measurements. The experimental method is based on measurement of electric field inside the enclosure using an electric field probe with small dimensions is described in the paper. Solution of an illustrative example of SE by FEM is shown and simulation results are verified by experiments. [ABSTRACT FROM AUTHOR]

A single-species population model exhibiting a symmetric slow variation for the carrying capacity and intrinsic growth rate is evaluated explicitly. However, it is unrealistic to eliminate the possibility of a clear separation in the evolution of the biotic environmental elements; thus, this paper considers the situation where these elements have a hierarchical variation on the time scales. Accordingly, two particular situations are recognized, which are the carrying capacity varies faster than the growth rate and vice versa. Applying the multi-time scaling technique in such a system provides a small parameter, which leads us to construct analytical approximate expressions for the population behavior, using the perturbation approach. Such approximations display very good agreement with the numerical simulations. [ABSTRACT FROM AUTHOR]

A new design and analysis of a wide-band double-negative metamaterial, considering a frequency range of 0.5 to 7 GHz, is presented in this paper. Four different unit cells with varying design parameters are analyzed to evaluate the effects of the unit-cell size on the resonance frequencies of the metamaterial. Moreover, open and interconnected 2 × 2 array structures of unit cells are analyzed. The finite-difference time-domain (FDTD) method, based on the Computer Simulation Technology (CST) Microwave Studio, is utilized in the majority of this investigation. The experimental portion of the study was performed in a semi-anechoic chamber. Good agreement is observed between the simulated and measured S parameters of the developed unit cell and array. The designed unit cell exhibits negative permittivity and permeability simultaneously at S-band (2.95 GHz to 4.00 GHz) microwave frequencies. In addition, the designed unit cell can also operate as a double-negative medium throughout the C band (4.00 GHz to 4.95 GHz and 5.00 GHz to 5.57 GHz). At a number of other frequencies, it exhibits a single negative value. The two array configurations cause a slight shift in the resonance frequencies of the metamaterial and hence lead to a slight shift of the single- and double-negative frequency ranges of the metamaterial. [ABSTRACT FROM AUTHOR]