Study on modeling and simulation of the Graphene and CNT

Top PDF Study on modeling and simulation of the Graphene and CNT:

Modeling and Simulation of Graphene Based Polymer Nanocomposites: Advances in the Last Decade

Modeling and Simulation of Graphene Based Polymer Nanocomposites: Advances in the Last Decade

Various theoretical and computational approaches have been employed to explore the effect of graphene as reinforcement on the performance of polymer nanocomposites including but not limited to, quantum mechani- cal-based methods [28], Continuum Mechanics (CM) [29], Molecular Mechanics (MM) [30], Molecular Dy- namics (MD) [31], atomistic modeling [32], Density Functional Theory (DFT) [33], and multiscale modeling [34]. The mechanical, thermal, and electrical properties of GBPNCs have widely been studied. Cao [35] has re- viewed the atomistic studies on the mechanical properties of graphene and Allegra et al. [36] have reviewedthe modeling of polymer nanocomposites reinforced with spherical nanoparticles or statistically isotropic aggregates. The high strength and stiffness of graphene significantly improve the mechanical properties of polymer nano- composites. Cho et al. studied the mechanical properties of graphene-epoxy nanocomposites with a combination of MM and Mori-Tanaka Method (MTM) [37]. The properties of nanocomposites are also dependent on the po- lymer chain networking. Yarovsky and Evans studied the structure and properties of crosslinked polymers using computer simulations [38]. Awasthi et al. used MD simulation to study the load-transfer mechanism at nanos- cale in graphene-polyethylene nanocomposites [39]. Due to the semblance of graphene, it is considered as frame-like structure. In the frame, covalent C-C bonds are taken as beams joined together with carbon atoms placed at the joints. Uniaxial beam elements, defined by their cross-sectional area, material properties, and mo- ment of inertia represent the covalent bonds. The parameters of the beam elements are determined by establish- ing equivalence between structural mechanics and computational chemistry. To generalize the models for GBPNCs, graphene can be wrapped within a “model material” which represents various kinds of polymer ma- trices as shown in Figure 4. The model material allows systematic manipulation of influencing factors, and ac- cordingly, it provides a tunable elastic platform to determine the overall performance of GBPNCs. The model material allows methodical variation of material properties beyond the capacity of experimental methods.
Show more

47 Read more

Modeling of polyethylene, poly(l lactide), and CNT composites: a dissipative particle dynamics study

Modeling of polyethylene, poly(l lactide), and CNT composites: a dissipative particle dynamics study

Molecular dynamics simulation was carried out using the Discover and Amorphous Cell module of Material Studio 4.3, developed by Accelrys Software, Inc (10188 Telesis Court, Suite 100, San Diego, CA 92121, USA). The compass potential and Andersen thermostat were used in our simulation. The time step of 1 fs was set for the time integration. Figure 1 shows the chemical struc- ture of PLLA and PE. To calculate the compressibility, the mixing energy, and the Flory-Huggins parameter, the equilibrium structure of the CNT, PE, PLLA, CNT- PLLA, PLLA-PE, and CNT-PE composite should be obtained from MD. All processes of obtaining the inter- action parameters were similar to our previous study [26]. The Flory-Huggins parameter can describe the mixing effect. The relationship between Flory-Huggins parameter and mixing energy is shown below:
Show more

8 Read more

Stress Transfer Modeling in CNT Reinforced Composites using Continuum Mechanics (TECHNICAL NOTE)

Stress Transfer Modeling in CNT Reinforced Composites using Continuum Mechanics (TECHNICAL NOTE)

highly ductile deformation suggest that carbon nanotubes may hold a promising characteristic as reinforcement for nanocomposites [1]. The improvements in stiffness and strength due to the addition of carbon nanotubes in brittle and ductile matrixes have been demonstrated by some experimental and analytical results [2]. There has been tremendous interest in the modeling and simulations of the CNT composites in order to characterize their mechanical properties for potential engineering applications. There are many researches dealing with the elastic properties of the carbon nanotube through various means, in elastic and inelastic behavior [3]. To understand the properties of nanotube reinforced composites, a fundamental challenge exists in the characterization and modeling of these materials at the nanoscale. Both molecular dynamics and continuum mechanics and their combinations have been attempted for this purpose. Among the available literature, Lordi, et al [4] used force- field-based molecular mechanics to model the interactions between nanotubes and several different kinds of polymers. Wise, et al [5] used molecular dynamics simulation to address the local changes in the interface of a single-walled nanotube surrounded by polyethylene molecules. These approaches typically involve extensive computations and tend to be configuration specific. The MD approach is necessary in the study of nanocomposites, especially for investigating local interactions of CNTs with matrix materials. However, MD simulations at present are limited to small length and time scales due to the limitations of the current computing power [6]. Continuum mechanic approaches can fill this gap and results from such approaches have been shown to be close to those of the atomistic based simulations. Although efficient in computing and able to handle models at larger length scales, simulation results are obtained, using the continuum mechanics approach which should be interpreted correctly. Attention should be given to the overall deformations or load transfer mechanisms rather than local properties. There are some recent efforts to develop the continuum theories to modeling nanoscale composites [9-14]. Pipes, et al [9] characterized the mechanical properties of CNT composites using a continuum mechanics approach. Applying the traditional textile-
Show more

8 Read more

Study on mechanical properties of CNT reinforced LM20 Alloy Nanocomposite

Study on mechanical properties of CNT reinforced LM20 Alloy Nanocomposite

Al-Si (BS: LM20) alloy was used as the matrix material. The alloy contains 12.00 wt.% Si, 0.1 wt.% Mg, 0.1 wt.% Cu, 0.80 wt.% Fe, 0.50 wt.% Mn and balance was Al. LM20– 0.25,0.5,0.75 wt.% CNT composite was prepared by dispersing fine particles in aluminium alloy matrix using powder metallurgy technique. The steps involved in preparing the composite were blending of powder, mixing of aluminium alloy powder with carbon nanotube using high speed ball milling and compaction.

9 Read more

Simulation of Graphene Piezoresistivity Based on Density Functional Calculations

Simulation of Graphene Piezoresistivity Based on Density Functional Calculations

lowest CB subband are in double degeneracy at the Y point, in the vicinity of the Fermi energy. This feature can be also derived by the simple Hückel method qualita- tively for the armchair model, as shown in Figure 4. As the common characteristic of the armchair models, the π orbitals of all of armchair models are localized at the edges of graphene ribbon, and no conductance path exists in the center of graphene ribbon. The interaction due to π orbitals along the longitudinal direction is very small because of the non-bonding state due to the anti-sym- metric relation for the translation with the phase factor
Show more

7 Read more

Systems Analysis, Modeling, and Simulation

Systems Analysis, Modeling, and Simulation

(representative or simulations) are established, when needed, to support conduct of a formal or informal trade study. The selection of models depends on the nature of the trade-off analysis, the development stage, the type of information needed, and the characteristics of interest for an alternative. Models should be validated prior to application in a trade-off analysis.

311 Read more

MODELING AND SIMULATION OF A MANUFACTURING ENVIRONMENT

MODELING AND SIMULATION OF A MANUFACTURING ENVIRONMENT

The Project Leader (PL) has visited several international sites concerning with manufacturing cell research, developing, and industrial applications. So he could gathered up-to-date information about the main trends on this subject. The first visited unit was the ISW Institute of Stuttgart University-Prof. Stute (1981), followed by the Brazilian- Italian Center in Rio de Janeiro (1983), the Vuste Institute in Praga (1984), the Comau Cell at Milano Fair (1987), the FMS facilities at the Universidad Politecnica de Madrid , Aracil and Puente (1993), the FMC of INSA Lyon Institute, Jutard (1993), and the Institute for Robotics and Intelligent Systems–IRIS USC, Koshnevis (1997). The representative sites among the argentine cell manufacturing facilities are: the two Comau Cells at CTA Center (1988) and Fiat Auto (1991) both in Cordoba city, the assembling spot welding Cell at Ford Buenos Aires (1994) the Cefodti Center at the Universidad Tecnológica Nacional-UTN, Buenos Aires (1994) and the tutorial FMS System at the Instituto Nacional de Educación Tecnológica (INET) in Buenos Aires (2000). With this acquired background experiences, the PL an his team decided to build up two experimental flexible manufacturing cells (FMC). With the Bid-Conicet #83 budget support, an industrial purpose cell composed by an American CNC mill, a Promecor CNC lathe and an arc-welding Cloos Romat robot was assembled. The other one is a research and developing (R&D) manufacturing cell named “Celflex” integrated by two robots: RSA-1 and RSA-2, and two computer numerical control machine tools (CNC MT) called Elinon 1 and Elinon 2 ( this under construction), presented in the Figure 1. Its main objective is to obtain a R&D integrated operational environment intended for manufacturing raw work-pieces in a random way, just as it is found in a small batch production. Figure 2 shows the cell pyramid hierarchical simulation and control layout. Modeling and simulation are the first mandatory steps for a proper analysis conducted to an optimized system operation.
Show more

10 Read more

Modeling and simulation of forging processes

Modeling and simulation of forging processes

Abstract: Forging is an experience-oriented technology. The physical phenomena that describe the forging operations are difficult to express with quantitative relationships. In order to avoid the trail-and-error method, we use numerical simulations for studying the forging process. With the help of these simulations, the engineers are able to uncover the potential defects which may happen during the forging process. Concurrent Engineering (CE) helps in making the forging process more effective. In the CE system, each modification of the product represents a taxonomical relationship between specifications, outputs, and the concept it represents. In the study, the forging process of a disc shaped part is analysed. Thanks to numerical simulations it is determined that the dimensions of the billet are larger than needed. This resulted in overfilling the flash of the tool, thus the simulation was unsuccessful. After correcting the dimensions of the billet, the simulation ran with no interruptions.
Show more

5 Read more

Simultaneous Determination of Dihydroxybenzene Isomers using Glass Carbon Electrode Modified with 3D CNT-graphene Decorated with Au Nanoparticles

Simultaneous Determination of Dihydroxybenzene Isomers using Glass Carbon Electrode Modified with 3D CNT-graphene Decorated with Au Nanoparticles

be found that the peak current height is in the following sequence: I(A u NPs) < I(Au NPs/CNT) < I(Au NPs/graphene) < I(Au NPs/CNTs/graphene). From these results, we can conclude that the introduction of CNTs or graphene both improve the electrocatalytic activities of Au NPs toward dihydroxybenzene due to the large surface area and excellent conductivity of these carbon nanomaterials. The integration of CNTs and graphene to form 3D CNTs/graphene nanostructure further enlarged the electrocatalytic activities of Au NPs to achieve the highest peak currents for oxidation of three isomers. At Au NPs/CNTs/graphene/GCE, the oxidation peak potentials of HQ, CC and RC is located at 0.15,0.26 and 0.65 V respectively, with the adjacent peak to peak separation of 0.11 and 0.39 V, suggesting the feasibility of Au NPs/CNTs/graphene hybrids for identification and simultaneous detection of the three isomers. For the cathodic curve, only two cathodic peak were observed, corresponding to reduction of HQ and CC respectively. There was no reduction peak of RC observed owning to the irreversible process for the electrochemical reaction of RC.
Show more

10 Read more

Mathematical Modeling and Simulation Study for the Control and Transmission Dynamics of Measles

Mathematical Modeling and Simulation Study for the Control and Transmission Dynamics of Measles

In figure 6, simulation study shows the result of the impact of testing and therapy of exposed individual at Latent period with the rate and the reproduction number and the other parameter values are as mentioned above. The population dynamics of epidemic compartmental model are considered. The exposed latent individuals increase to 382 initially and then decrease to zero. Also the infectives with early symptom or infected catarrh increase to 82 initially but during later times decrease to zero. The infected with later symptom or infected eruption individuals increase to 68. Recover compartment increases to 591. Finally the epidemic seems exist. This means that one infected person transmits disease for more than one person and measles disease spread continuous in the society.
Show more

9 Read more

Graphical modeling of binary data using the LASSO: a simulation study

Graphical modeling of binary data using the LASSO: a simulation study

Background: Graphical models were identified as a promising new approach to modeling high-dimensional clinical data. They provided a probabilistic tool to display, analyze and visualize the net-like dependence structures by drawing a graph describing the conditional dependencies between the variables. Until now, the main focus of research was on building Gaussian graphical models for continuous multivariate data following a multivariate normal distribution. Satisfactory solutions for binary data were missing. We adapted the method of Meinshausen and Bühlmann to binary data and used the LASSO for logistic regression. Objective of this paper was to examine the performance of the Bolasso to the development of graphical models for high dimensional binary data. We hypothesized that the performance of Bolasso is superior to competing LASSO methods to identify graphical models.
Show more

13 Read more

A Modeling & Simulation Framework for Large-Scale Simulation

A Modeling & Simulation Framework for Large-Scale Simulation

Classical High Level Architecture (HLA) systems are facing development problems for lack of supporting fine-grained component integration and interoperation in large-scale complex simulation applications. To provide efficient methods of this issue, an extensible, reusable and composable simulation framework is proposed. To promote the reusability from coarse-grained federate to fine-grained components, this paper proposes a modelling & simulation framework which consists of component-based architecture, modelling methods, and simulation services to support and simplify the process of complex simulation application construction. Moreover, a standard process and simulation tools are developed to ensure the rapid and effective development of simulation application.
Show more

8 Read more

Modeling and simulation of call centers

Modeling and simulation of call centers

impose severe restrictions on the routing (a crossed routing as in section 3 is not allowed) and develop an approxima- tion of the loss rate for each call type that is claimed to be superior to other known approaches. Bhulai (2004) approx- imates an optimal routing policy via dynamic programming; one-step policy improvement of a “good” initial policy is proposed as a means to making the procedure practical, given that the state space is very large (high-dimensional) in typical applications. Chevalier et al. (2004) work with loss-type models of a call center that is staffed with a mix- ture of single-skill and fully-flexible agents. They show that routing calls first to specialists, then (if necessary) to fully-flexible agents, minimizes the loss rate. Further, they adapt Hayward’s approximation (see Wolff (1989), pp. 354- 355) to support minimum-cost staffing subject to loss-rate performance constraints. The simple rule-of-thumb “80% specialist, 20% fully-flexible agents” is shown to work well in their examples. Avramidis et al. (2005) extend the ideas of Koole and Talim (2000) to model call queueing, allowing abandonment and an arbitrary overflow routing (including the crossed case); they approximate the tail of the distribution of virtual queue time (see section 7.3) for each call type. Such performance approximations may be useful as pure alternatives to simulation or in synergy with simulation, typically to support the staffing and schedul- ing decisions. In Avramidis et al. (2005), synergy between the analytical performance approximation and simulation was essential to solving efficiently single-period multi-skill staffing problems (see Section 4).
Show more

9 Read more

19 MODELING, SIMULATION & TRAINING

19 MODELING, SIMULATION & TRAINING

Most of the optics and photonics compa- nies in this region are relatively small, employing seven people or fewer with yearly revenue of $900,000, the USF study shows. But there are some big firms such as Honeywell, primarily a St. Petersburg aero- space company that makes use of optics. (Honeywell Corp. reports annual revenue of more than $8 billion.) Lockheed Martin is another big player with more than $500 mil- lion a year in revenue. It makes military elec- tronics and missiles and has offices in Orlando, Cape Canaveral and Cocoa Beach. Others include Clearwater’s Sensidyne Inc., which makes toxic and combustible gas detection systems, among other products; Litton Laser Systems Inc. of Apopka, which makes search and navigation equipment; and Schwartz Electro Optics Inc., an Orlando company making laser-based sensors.
Show more

40 Read more

Modeling and Simulation of Robot Fish

Modeling and Simulation of Robot Fish

Fish are the best swimmers of the sea. The use of flexible tail movements is for good swimmers, for fast swimming and sudden swapping movements. This resulted in fish inspirations in the design of underwater vehicles.In this study, it is aimed to imitate four degrees of freedom (DOF) of the structure of the carangiform fish that is based on the results of previous studies. The equations of the motion of the carangiform type carp fish robot are obtained to simulate angle values required for the robot fish swimming using Matlab/Simulink/SimMechanics software. While determining the backbone structure of the robot fish, four joints are designed considering the dimensions of real carp fish and, also the joints are placed in positions where the robot fish can best mimic the movement of the tail. Moreover three actuators are located to body for advancement, rotation and sinking movements. Modeling and simulations results of the proposed research are given in figures and important findings are realized for future control studies in terms of the modeling approaches.
Show more

9 Read more

SLS Vehicle Modeling and Simulation

SLS Vehicle Modeling and Simulation

 Using discrete event simulation to model the operations process, assembly, test, etc. To optimize the flow, understand the long poles in the tent, and understand how long each operation will take.  Modeling of solid rocket booster options using stick traces and

35 Read more

BUSINESS PROCESS MODELING AND SIMULATION

BUSINESS PROCESS MODELING AND SIMULATION

Considering the BP modeling problem in terms of the queueing theory we can say that a queueing system fulfils the incoming orders of the BP instances execution. Since a serving system is a basic element of a queuing system, then the problem turns out to be the task of modeling a serving system. The latter accomplishes such activities as queuing, seizing a server, service processing, and releasing a server. Each of these activities has its mapping into the appropriate GPSS statement. A typical segment of the BP GPSS program shown below.

118 Read more

The Big Bock of Simulation Modeling

The Big Bock of Simulation Modeling

Example 11.8: Creating agent populations parameterized from a database ... 16 The Big Book of Simulation Modeling · Multimethod Modeling with AnyLogic 6[r]

12 Read more

Study on appropriate and modified conditions for flash sintering process by simulation modeling

Study on appropriate and modified conditions for flash sintering process by simulation modeling

Flash sintering is one of the newest techniques for sintering ceramics to near full density. It occurs in an appropriate combination of temperature and electric field. Temperature measurement is one of the most serious challenges in this process. In the present study, we tried to model a flash sintering process of 8YSZ and 3YSZ with finite element method to make an assessment for temperature distribution and also to estimate the critical values of temperature and electric field intensity. Results indicated the correlation between furnace temperature and electric field intensity and also uniformity of current passage through the sample can be observed by simulation modeling. Keywords:
Show more

5 Read more

Study on Modeling and Simulation of Leg Hydraulic System of Trailer Concrete Pump

Study on Modeling and Simulation of Leg Hydraulic System of Trailer Concrete Pump

According to the working principle of leg hydraulic system of a trailer concrete pump, the simulation model of leg hydraulic system is established based on AMESim, and the dynamic characteristics of leg hydraulic system is analyzed. The research result indicates that with the gravity center moves to a leg, the pressure in the corresponding cylinder will increase, and the velocity of the rod will decrease. The greater the gravity center offsets, the greater the influence of the dynamic characteristics. In order to reduce the damage to the leg cylinder, the gravity center and the geometry center should be coincident as much as possible when using a trailer concrete pump.
Show more

5 Read more

Show all 10000 documents...