31 results
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2. Mathematical Modeling and Optimal Control of Intervention Strategies for A Banditry Model.
- Author
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Momoh, Abdulfatai Atte, Musa, Solomon, Alkali, Muhammad Adamu, and Inalegwa, Ali Micheal
- Subjects
PONTRYAGIN'S minimum principle ,MATHEMATICAL models ,COMPUTER simulation ,ELECTROMECHANICAL analogies ,SIMULATION methods & models - Abstract
This paper presents an optimal control of intervention strategies for the menace of Banditry taking into account media campaign against Banditry u
2 (t) rehabilitation of Bandits detainees u5 (t) and use of military force against Banditry u6 (t) as control strategies. The Banditry free equilibrium, Banditry present equilibrium and the basic reproduction number of Banditry R0B were obtained. The stability analysis results suggest that the Banditry free equilibrium is locally asymptotically stable when R0B >1 and otherwise when R0B >1. The Boko Haram presence equilibrium is globally asymptotically stable when R0B >1 and unstable if R0B >1. We used the three control strategies and updated the Banditry menace model. The optimal control issue was resolved using Pontryagin's Maximum Principle (PMP). It was discovered that there is a significant decrease in the population of Bandits and increase in the number of rehabilitated Bandits and detained Bandits when the control measures are implemented compared to the case without control. We solved the optimality control using a forward-backward sweep strategy implemented in MATLAB for numerical simulation. Additionally, we saw that the number of people detained fluctuates as the number of people receiving rehabilitation rises. We argue that in order to lessen or completely erase the menace caused by Bandits in society, the government should fund media campaigns and rehabilitation initiatives. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
3. Improvement on acoustic characteristics of a small space using material selection.
- Author
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Shih, Hsin-Yi, Chou, Yu-Tuan, and Hsia, Shao-Yi
- Subjects
ECONOMIC development ,ECONOMIC policy ,COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models - Abstract
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]
- Published
- 2016
- Full Text
- View/download PDF
4. Analysis of an SIQR model.
- Author
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MAITI, ALAKES, SEN, PROSENJIT, and SAMANTA, G. P.
- Subjects
EPIDEMIOLOGICAL models ,MATHEMATICAL models ,EPIDEMIOLOGY ,COMPUTER simulation ,ELECTROMECHANICAL analogies - Abstract
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]
- Published
- 2018
- Full Text
- View/download PDF
5. Numerical Simulation of the Propagation of Hydraulic and Natural Fracture Using Dijkstra's Algorithm.
- Author
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Yanfang Wu and Xiao Li
- Subjects
COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,SIMULATION methods & models ,NATURAL gas extraction - Abstract
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]
- Published
- 2016
- Full Text
- View/download PDF
6. A Nonlinear Model of Mix Coil Spring - Rubber for Vertical Suspension of Railway Vehicle / Nieliniowy model połaczenia sprezyny srubowej i elementu gumowego w zawieszeniu pionowym pojazdu szynowego.
- Author
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Dumitriu, Mădălina
- Subjects
RAILROADS ,COMPUTER simulation ,COMMERCIAL trusts ,ELECTROMECHANICAL analogies ,MATHEMATICAL models - Abstract
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]
- Published
- 2016
- Full Text
- View/download PDF
7. Shielding Effectiveness Simulation of Small Perforated Shielding Enclosures Using FEM.
- Author
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Kubík, Zdenĕk and Skála, Jiří
- Subjects
SIMULATION methods & models ,COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,DEGREES of freedom - Abstract
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]
- Published
- 2016
- Full Text
- View/download PDF
8. Physically based modeling in catchment hydrology at 50: Survey and outlook.
- Author
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Paniconi, Claudio and Putti, Mario
- Subjects
HYDROLOGIC models ,HYDROLOGY ,WATERSHEDS ,HYDRAULICS ,ELECTROMECHANICAL analogies ,MATHEMATICAL models - Abstract
Integrated, process-based numerical models in hydrology are rapidly evolving, spurred by novel theories in mathematical physics, advances in computational methods, insights from laboratory and field experiments, and the need to better understand and predict the potential impacts of population, land use, and climate change on our water resources. At the catchment scale, these simulation models are commonly based on conservation principles for surface and subsurface water flow and solute transport (e.g., the Richards, shallow water, and advection-dispersion equations), and they require robust numerical techniques for their resolution. Traditional (and still open) challenges in developing reliable and efficient models are associated with heterogeneity and variability in parameters and state variables; nonlinearities and scale effects in process dynamics; and complex or poorly known boundary conditions and initial system states. As catchment modeling enters a highly interdisciplinary era, new challenges arise from the need to maintain physical and numerical consistency in the description of multiple processes that interact over a range of scales and across different compartments of an overall system. This paper first gives an historical overview (past 50 years) of some of the key developments in physically based hydrological modeling, emphasizing how the interplay between theory, experiments, and modeling has contributed to advancing the state of the art. The second part of the paper examines some outstanding problems in integrated catchment modeling from the perspective of recent developments in mathematical and computational science. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
9. Numerical approximations for a three-component Cahn-Hilliard phase-field model based on the invariant energy quadratization method.
- Author
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Yang, Xiaofeng, Zhao, Jia, Wang, Qi, and Shen, Jie
- Subjects
CAHN-Hilliard-Cook equation ,PARTIAL differential equations ,COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models - Abstract
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]
- Published
- 2017
- Full Text
- View/download PDF
10. PROPERTY AND NUMERICAL SIMULATION OF THE AIT-SAHALIA-RHO MODEL WITH NONLINEAR GROWTH CONDITIONS.
- Author
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FENG JIANG, HUA YANG, and TIANHAI TIAN
- Subjects
COMPUTER simulation ,INTEREST rates ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,SIMULATION methods & models - Abstract
The Ait-Sahalia-Rho model is an important tool to study a number of financial problems, including the term structure of interest rate. However, since the functions of this model do not satisfy the linear growth condition, we cannot study the properties for the solution of this model by using the traditional techniques. In this paper we overcome the mathematical difficulties due to the nonlinear growth condition by using numerical simulation. Thus we first discuss analytical properties of the model and the convergence property of numerical solutions in probability for the Ait-Sahalia-Rho model. Finally, an example for option pricing is given to illustrate that the numerical solution is an effective method to estimate the expected payoffs. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
11. Mathematical modelling of real transmission shafts and mechanical connections with clearances.
- Author
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POPENDA, Andrzej
- Subjects
POWER transmission ,ELECTROMECHANICAL analogies ,ELECTRIC motors ,MATHEMATICAL models ,ELASTICITY - Abstract
Copyright of Przeglad Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2017
- Full Text
- View/download PDF
12. Interaction between scale and scheduling choices in simulations of spatial agents.
- Author
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Bonnell, Tyler R., Chapman, Colin A., and Sengupta, Raja
- Subjects
COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,SIMULATION methods & models ,COMPUTER simulation of adsorption - Abstract
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]
- Published
- 2016
- Full Text
- View/download PDF
13. High-performance simulation of fracture in idealized ‘brick and mortar’ composites using adaptive Monte Carlo minimization on the GPU.
- Author
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Lim, Rone Kwei, Pro, J. William, Begley, Matthew R., Utz, Marcel, and Petzold, Linda R.
- Subjects
COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,FRACTURE mechanics ,MONTE Carlo method - Abstract
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]
- Published
- 2016
- Full Text
- View/download PDF
14. A Slow Single-Species Model with Non-Symmetric Variation of the Coefficients.
- Author
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Alharbi, Fahad M.
- Subjects
COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,SIMULATION methods & models ,COEFFICIENTS (Statistics) - Abstract
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]
- Published
- 2022
- Full Text
- View/download PDF
15. Ferrogels cross-linked by magnetic nanoparticles—Deformation mechanisms in two and three dimensions studied by means of computer simulations.
- Author
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Weeber, Rudolf, Kantorovich, Sofia, and Holm, Christian
- Subjects
- *
NANOPARTICLES , *NANOSTRUCTURED materials , *COMPUTER simulation , *ELECTROMECHANICAL analogies , *MATHEMATICAL models - Abstract
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]
- Published
- 2015
- Full Text
- View/download PDF
16. A New Wide-Band Double-Negative Metamaterial for C- and S-Band Applications.
- Author
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Hossain, Md Ikbal, Faruque, Mohammad Rashed Iqbal, Islam, Mohammad Tariqul, and Ullah, Mohammad Habib
- Subjects
MODEL-integrated computing ,ELECTROMECHANICAL analogies ,COMPUTER simulation ,COMPUTER-aided design ,MATHEMATICAL models - Abstract
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]
- Published
- 2015
- Full Text
- View/download PDF
17. Finite-time synchronization for a class of fuzzy cellular neural networks with time-varying coefficients and proportional delays.
- Author
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Wang, Wentao
- Subjects
- *
COMPUTER simulation , *ELECTROMECHANICAL analogies , *MATHEMATICAL models , *FEEDBACK control systems , *NEURAL circuitry - Abstract
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]
- Published
- 2018
- Full Text
- View/download PDF
18. A New Test Point Selection Method for Analog Continuous Parameter Fault.
- Author
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Luo, Hui, Lu, Wei, Wang, Youren, and Wang, Ling
- Subjects
- *
VOLTAGE control , *ALGORITHMS , *COMPUTER simulation , *ELECTROMECHANICAL analogies , *MATHEMATICAL models - Abstract
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]
- Published
- 2017
- Full Text
- View/download PDF
19. PM exposure variations due to different time activity profile simulations within a single dwelling.
- Author
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McGrath, J.A., Sheahan, J.N., Dimitroulopoulou, C., Ashmore, M.R., Terry, A.C., and Byrne, M.A.
- Subjects
AIR pollutants ,AIR pollution ,COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models - Abstract
This paper describes the combination of a physical pollutant model IAPPEM with a time activity profile, to create an air pollutant personal exposure model. A previous study has already demonstrated the capability of IAPPEM in predicting indoor Particulate Matter (PM) concentrations in a residential environment. The present work investigates personal exposure variability between individuals and, doors opened vs closed scenarios, by examining the movements of four individuals through the same dwelling. The results of the simulations highlight the distinction between personal exposure and indoor concentrations, providing computational validation to well-documented experimental differences that exist between indoor concentrations and personal exposure. Using IAPPEM, personal exposure is calculated according to the percentage contribution from the time spent in each room, illustrating that the periods of presence, in relation to the times of indoor source emission, are as important as the durations spent in each room. This study provides a comparison between two approaches for evaluating personal exposure: a time-weighted average and a time activity profile. The results showed that a time-weighted averaged profile is a poor substitute when compared with personal exposure calculated based on a time activity profile, as, in each simulated scenario, exposures were under-predicted using the time-weighted approach, in some cases by up to 135%. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
20. Charge accumulation patterns on spacer surface in HVDC gas-insulated system: Dominant uniform charging and random charge speckles.
- Author
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Zhang, Boya, Qi, Zhe, and Zhang, Guixin
- Subjects
- *
HIGH-voltage direct current transmission , *COMPUTER simulation , *ELECTROMECHANICAL analogies , *MATHEMATICAL models , *SIMULATION methods & models - Abstract
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]
- Published
- 2017
- Full Text
- View/download PDF
21. Numerical Study on the Ballistic Impact Response of Aramid Fabric- epoxy Laminated Composites by Armor Piercing Projectile.
- Author
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Nayak, N., Banerjee, A., and Panda, T.R.
- Subjects
LAMINATED materials ,IMPACT response ,COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models - Abstract
This paper presents the results from experiments and numerical simulations on the ballistic impact of 10 mm thick aramid fabric-epoxy composite laminates by a 7.62 mm armor piercing projectile at varying impact velocities. Post perforated residual velocity (RV), contact duration of projectile with the target and ballistic limit (BL) of composite were simulated using a finite element code HyperWorks-Radioss. Interaction of projectile with composite laminates was captured by high speed video. The predicted ballistic parameter from simulation compared well with the precision experimental results. The simulated energy and stress distribution during impact of projectile on composite laminate showed marked difference with variation in impact velocities (SV). The magnitude and duration of stress as well as the contact force was found to increase when projectile impacted at lower SV thus enhancing the extent of delaminating and the core damage area and the trend was reversed for higher SV. The findings corroborate the bullet inflicted damage of composite laminates experimentally determined by ultrasonic C-scan. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
22. Model of banana screen for robust performance.
- Author
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Asbjörnsson, Gauti, Bengtsson, Magnus, Hulthén, Erik, and Evertsson, Magnus
- Subjects
- *
BANANAS , *COMPUTER simulation , *ELECTROMECHANICAL analogies , *MATHEMATICAL models , *SIMULATION methods & models - Abstract
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]
- Published
- 2016
- Full Text
- View/download PDF
23. Computer Simulation of Methanol Exchange Dynamics around Cations and Anions.
- Author
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Roy, Santanu and Dang, Liem X.
- Subjects
- *
COMPUTER simulation , *ELECTROMECHANICAL analogies , *MATHEMATICAL models , *METHANOL , *ALCOHOLS (Chemical class) - Abstract
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]
- Published
- 2016
- Full Text
- View/download PDF
24. A delayed-feedback filter with negative group delay.
- Author
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Voss, Henning U.
- Subjects
COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,SIMULATION methods & models ,TIME delay systems - Abstract
A filter with delay-induced negative group delay is presented. The filter consists of multiple time-delayed feedback terms, which lead to a negative group delay for frequencies in the baseband. It can be used for the real-time prediction of band-limited signals. The filter is universal as it does not rely on a specific model of the signal. Specifically, as long as the signal to be predicted is band-limited with a known cutoff frequency, the filter predicts the signal in real time up to a prediction horizon that depends on the cutoff frequency. How signal prediction arises from the negative group delay of the filter is worked out in detail. Its properties, including stability, are derived analytically and demonstrated by numerical simulations. For chaotic systems, the filter is predictive during phases of high predictability. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
25. Response of welded aluminium alloy plates for ballistic loads.
- Author
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Srikanth, Thimmapuram, Surendran, S., Balaganesan, G., and Manjunath, G. L.
- Subjects
ALUMINUM alloys ,ECONOMIC determinism ,COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models - Abstract
Light-weight metals like aluminium are preferred to for building of high speed crafts, naval ships, superstructures of commercial ships and offshore platforms. In plate joining, the efficiency of joint is a measure of its impact resistance and structural-integrity. The plates welded together should function effectively against any external loads under emergencies. An ideal welded joint should possess superior weld strength with good impact resistance. Cold metal transfer (CMT) is a proven type of welding technique which is proposed for marine fabrications. Plates of aluminium alloys with grade AA5086-H111 and AA6061-T6 are welded together using a filler, AA4043. For the purpose of plate joining, parameters like current, voltage, arc length, shield gas pressure, etc. are varied to arrive at a continuous weld without any crack. In this study, welded thin plates are subjected to tensile test and thereafter impact loads are applied. The plates are subjected to impact loads in the range of sub-ordinance level velocities, feasibility of ordinance and ultra-ordinance can be scaled and compared. Thus, various ballistic loads are applied at the welded joints. Response and terminal ballistics limit are determined for thin plates of thickness 1.2 and 3 mm plates. This study consists of simulation in Abaqus software and experiments using a gun prepared in the laboratory. It was observed that, there was petaling in very thin plates and perforations by plugging for lower ballistic loads and thinner plates. The work gives new insights in the application of CMT in joining of plates of different metals with varied thickness values. The experimental results can be used as bench marks to compare results of simulations for thin plates. While experiments were done for thin plates, only computer simulation was done for thicker plate of 12 mm which is usually accepted for fabrication in industry. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
26. Design, analysis and simulation of a novel linear capacitive tilt micro-sensor.
- Author
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Mir, Fahimeh and Mehran, Mahdiyeh
- Subjects
COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,DETECTORS ,ENGINEERING instruments - Abstract
A new capacitive structure for tilt sensor based on the MEMS technology is designed, analyzed and simulated. With a detailed analysis, we achieve to a precise relation between capacitance and inclination angle. Taking advantage of cylindrical structure in our design, we reach to a linear relationship between capacitance and tilt angle. In three designs of our capacitive tilt micro-sensor, there are 1, 2 and 4 micro capacitors. These capacitors have a common plate of mercury which is movable. Another plate is fixed. Displacement of mercury according to the deflection tends to the variations of capacitors and subsequently total capacitance of the tilt micro-sensor changes. In each of three designs for this micro-sensor, output capacitance (C) is introduced with a special equation for obtaining a linear and continues relationship between C and tilt angle. The last proposed micro-sensor structure with 4 micro capacitors, shows linear relationship for C over tilt measurement range of -180° to +180° on one axis besides proper sensitivity. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
27. Analytic Method of Stress Analysis for an Orthotropic Rock Mass with an Arbitrary-Shaped Tunnel.
- Author
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Aizhong Lu, Ning Zhang, Xiaoli Zhang, Donghai Lu, and Weisheng Li
- Subjects
STRAINS & stresses (Mechanics) ,SIMULATION software ,COMPUTER simulation ,MATHEMATICAL models ,ELECTROMECHANICAL analogies ,SIMULATION methods & models ,MECHANICAL stress analysis - Abstract
Rock mass often exhibits anisotropic properties. Even isotropic rocks will behave anisotropically if cut by regular joint sets. Many rock masses can be regarded as orthogonal anisotropic linear elastic bodies. To date, there is no analytic method available to determine the stresses in an arbitrary-shaped tunnel (except for elliptic holes and circles) in an orthogonal anisotropic rock mass under the action of in situ stresses. To obtain analytical solutions, the conformal transformation method is used, in which with three polar coordinates are introduced. By introducing the power series method, a new analytic method used to determine stresses in an orthogonal anisotropic rock mass with an arbitrary shaped tunnel is proposed. The analytic solutions are verified by numerical analyses using computer simulation software. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
28. Numerical simulations of spectral broadening in all-normal dispersion photonic crystal fiber at various pump pulse conditions.
- Author
-
Siwicki, Bartłomiej, Klimczak, Mariusz, Soboń, Grzegorz, Sotor, Jarosław, Pysz, Dariusz, Stępień, Ryszard, Abramski, Krzysztof, and Buczyński, Ryszard
- Subjects
COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,PHOTONIC crystal fibers ,OPTICAL fibers - Abstract
Supercontinuum (SC) generation contained in the normal dispersion range of an optical fiber has been shown to be limited primarily by the available peak power and length of the pump pulse. In this work, we numerically investigate the SC spectral width and flatness for various pump pulse conditions in a nonlinear, all-solid, soft-glass, photonic crystal fiber (PCF) with a flattened dispersion profile. We assume a range of pump pulse parameters with pulse lengths between 250 and 100 fs (60 to 150 kW of peak power), and input pulse energies between 10 and 30 nJ, numerically reaching a maximum SC width of 800 to 2600 nm. The presented theoretical study provides a guideline for the selection of a fiber laser pump source, or in other words, it enables one to expect the extent of spectral broadening in the developed, all-normal dispersion PCF, when presently available fiber laser pump pulse parameters are assumed. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
29. Report on IEEE/IEEJ workshop on computer simulation in polymer Dielectrics held in conjunction with ISEIM 2014 Niigata, Japan, on June 1, 2014.
- Subjects
COMPUTER simulation ,FORUMS ,ELECTROMECHANICAL analogies ,MATHEMATICAL models - Abstract
A workshop on "Computer Simulation in Polymer Dielectrics" was held on June 1, 2014, prior to ISEIM 2014 Niigata. It is called APIANS, which stands for Analysis for Polymeric Insulating Materials Using Advanced Numerical Simulation. Five experts in differing areas of computational dielectrics were invited to discuss their recent research and provide their vision for the future of computational dielectrics. The workshop, attended by more than 50 people, was well received. This report provides the outlines of the five speakers? presentations and some consideration for future direction. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
30. Use of Innovative and Advanced Computer Simulations of Chemical Speciation of Heavy Metals in Soils and Other Environmental Samples.
- Author
-
Jeske, Agnieszka
- Subjects
COMPUTER simulation ,ELECTROMECHANICAL analogies ,MATHEMATICAL models ,CHEMICAL elements ,METAL compounds - Abstract
Copyright of Soil Science Annual is the property of Polish Society of Soil Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2014
- Full Text
- View/download PDF
31. Supercapacitor Electro-Mathematical and Machine Learning Modelling for Low Power Applications.
- Author
-
Pozo, Borja, Garate, Jose Ignacio, Ferreiro, Susana, Fernandez, Izaskun, and Fernandez de Gorostiza, Erlantz
- Subjects
SUPERCAPACITORS ,MACHINE learning ,ELECTROMECHANICAL analogies ,COMPUTATIONAL complexity ,ARTIFICIAL neural networks ,MATHEMATICAL models - Abstract
Low power electronic systems, whenever feasible, use supercapacitors to store energy instead of batteries due to their fast charging capability, low maintenance and low environmental footprint. To decide if supercapacitors are feasible requires characterising their behaviour and performance for the load profiles and conditions of the target. Traditional supercapacitor models are electromechanical, require complex equations and knowledge of the physics and chemical processes involved. Models based on equivalent circuits and mathematical equations are less complex and could provide enough accuracy. The present work uses the latter techniques to characterize supercapacitors. The data required to parametrize the mathematical model is obtained through tests that provide the capacitors charge and discharge profiles under different conditions. The parameters identified are life cycle, voltage, time, temperature, moisture, Equivalent Series Resistance (ESR) and leakage resistance. The accuracy of this electro-mathematical model is improved with a remodelling based on artificial neuronal networks. The experimental data and the results obtained with both models are compared to verify and weigh their accuracy. Results show that the models presented determine the behaviour of supercapacitors with similar accuracy and less complexity than electromechanical ones, thus, helping scaling low power systems for given conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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