Analysis of Traffic Flow Based on the Finite Element Method

Traffic flow analysis was considered as one of the main steps in transportation planning and engineering. Various methods have been developed for this purpose. Most of these methods are based on available equations in traffic engineering. Mathematical methods used for analyzing traffic flow has always been very complicated and resource consuming. In 1995, using finite elements method for analyzing traffic flow was first introduced and developed over the few years. Hence it is a new look at traffic flow analysis which still needs lots of complex equations to be solved. In 2007, for the first time, it was suggested to simulate traffic flow as a fluid; using finite elements equations in fluid mechanics (i.e. model the vehicles in the road as a fluid in a canal). Results were considerably matching the real world case studies data. In this paper which is a part of study on the finite elements methods in transportation modeling and planning, ten different routes (e.g. bridge, intersection, roundabout) in Shiraz city (one of large scale cities of Iran) have been modeled in one of fluid mechanics modeling platform. Outputs compared with real world data by some adjustment and calibration which have been made to make it possible to match data and calculate the errors. Results show acceptable errors regarding modeling traffic flow by fluid mechanics simulation platforms. Additionally, a sensitivity analysis has been performed for acquisition of each element’s role (e.g. number of lanes, maximum allowed speed and AADT) in model accuracy in Neural Network Algorithm platform.

Objective To explore the establishment of 3D thoracic model by finite element methods, and study the mechanical mechanism of minimally invasive surgery for correcting the chest wall deformity, and provide personalized surgery solution in the future. Methods According to admission and exclusion criteria, we selected 10 cases of pectus carinatum that received chest CT scan. The finite element model of pectus carinatum was established and analyzed by Mimics, ABAQUS, etc. The validity of finite element method for chest wall was verified by comparing the sternal displacement between the simulated values and actual values with the same force. Results The 3D finite element model of pectus carinatum was successfully established and analyzed. The stress distribution of the 10 cases in the posterior ribs was mainly in the 1-6 ribs on both sides, mostly concentrated in the 4th to 6th ribs, and the stress was symmetrical on both sides. Statistical analysis showed that the displacement value of the sternum was correlated, and the validity of the model was verified. Conclusion Mimics, ABAQUS and other finite element modeling and analysis software can effectively establish the thoracic 3D finite element model and mechanical analysis, which can help the further development of personalized minimally invasive surgery for correcting chest wall deformities. Key words: Pectus carinatum; Chest wall deformity; Finite element analysis

Sıcak işleme olarak bilinen ısı destekli işleme, kesilmesi zor metallerin ve alaşımların işlenebilirliğini artırmak için alternatif bir işleme yöntemidir. Bu çalışma, endüstride yaygın olarak kullanılan Ti–6Al–4V alaşımının sıcak işlenmesinde kesme kuvvetlerinin sonlu elemanlar yöntemi ile incelenmesini içermektedir. İşleme deneyleri sonlu elemanlar analiz yazılımı olan ThirdWave AdvantEdge programında yapılmıştır. Bu analizlerde sabit kesme derinliğinde, kesme hızı (V), ilerleme hızı (f), ve sıcaklık parametreleri üçer seviye olarak belirlenmiştir. Deney listesi Taguchi L9 ortagonal dizilim ile oluşturulmuştur. L9 deney tasarımına göre kesme kuvvetleri değerleri kaydedilmiştir. Nümerik analiz sonuçlarına göre oda sıcaklığı koşullarının sıcak işleme koşullarına göre karşılaştırıldığında kesme kuvvetlerinin azaldığı görülmüştür. En düşük kesme kuvveti değeri 600°C sıcak işleme şartlarında gerçekleştirilen sayısal analizlerde ölçülmüştür.

In the past three decades, with the fast development of China's economy, the business data of electric power industry also showed rapid growth and the data size is continual expanding. Thus, the management systems of electric enterprise groups encountered the performance bottlenecks of massive data processing. Hadoop is an open-source software framework developed for reliable, scalable, and efficient distributed computing and storage, and is widely used in massive data processing. Based on the study of the proposed massive business data processing of electric industry, this paper introduces a novel architecture, which is based on Hadoop ecosystem, for management systems of electric enterprise groups to crack the present performance bottlenecks. First, the business logic and processing produce of management system is analyzed. Then new architecture with Hadoop based distributed processing model is introduced in detailed. At last, experimental results with actual business scenarios and data prove the architecture can effectively resolve present performance bottlenecks of massive business data processing, and greatly improve the performance and efficiency of the management system of electric enterprise groups.

Affected by the train vibration load, the frequency characteristics of the subway tunnel frequency spectrum are unstable, resulting in a low accuracy of the analysis results of the subway vibration load response characteristics. Therefore, the analysis method of the subway vibration load response characteristics based on the finite element method is designed. The acceleration index is used to evaluate the impact of vibration on the environment. According to the evaluation results, the soil constitutive model is constructed, the basic characteristics of the dynamic stress-strain relationship of the soil are analyzed, and the influencing factors of the vibration load calculation are determined. The three-dimensional finite element model of subway tunnel is established by using the finite element analysis software, and the linear time history analysis of the model is carried out by using the direct integration method. The time step is obtained to ensure the accuracy of the calculation results, so as to realize the accurate analysis of the response characteristics of subway vibration load. The experimental results show that the accuracy of the design method is high, and the frequency spectrum obtained by the analysis is basically the same as the actual frequency spectrum, which shows that the method has practical application significance.

Finite element method (FEM) has been widely used in recent years to analyze fiber-reinforced polymer (FRP) beams such as wind turbine blades. Although it is generic and convenient, FEM does little to shed light on the mechanical behavior of structures. Moreover, it is inefficient in calculation. This study presents a combined analytical and finite element beam (CAFB) model with an inclination angle correction to solve the non-prismatic, blade-like FRP beam problem. It not only substantially reduces computational time, but also helps us comprehend the mechanical behavior. Also, the inclination angle correction is supposed to correct the overestimated axial stiffness due to the topology of beams. In the presented cases, the CAFB model can accurately analyze the FRP thin-walled beams with all results being certified by finite element analysis software, and the correction is especially effective in small fiber orientation angles.

The handling and control of towed cable and body systems onboard surface ships and submarines presents a significant technical challenge to design engineers in the defense and ocean industries. The current approaches rely heavily on the empirical methods and the time-consuming and costly prototype testing. Computer simulation provides a cost effective way to reduce the high risks associated with the towed cable/body system. However, the current dynamic analysis of towed cables is mostly done by the finite difference (FD) method in stead of the finite element (FE) method that is widely used in almost all engineering fields. This paper presents an alternative FE method to simulate the dynamics of towed cable and body system, in which the large rigid body motion is coupled with small elastic deformation. The newly derived FE method is formulated in terms of element nodal positions, which is different from the existing FE methods that use displacements. The alternative FE method solves for the cable position directly in order to eliminate accumulated numerical errors arising from existing FE methods that solve for displacements first in order to obtain the cable position over very long period of time. The alternative FE formulation is implemented and applied to real applications to demonstrate its robustness by comparing simulation results with the experimental and sea trial data.

The interaction between off-road tires and granular terrain has a great influence on the tractive performance of off-road vehicles. However, the finite element method or the discrete element method cannot effectively study the interaction between off-road tires and granular terrain. The three-dimensional combined finite element and discrete element method is applied to handle this problem. In this study, a calibrated finite element method–discrete element method model is established, in which the finite element model of off-road tire is validated by stiffness tests, while the discrete element model of gravel particles is validated by triaxial compression tests. The calibrated finite element method–discrete element method model can describe the structural mechanics of the off-road tire and the macroscopic mechanical properties of the gravel road. Tractive performance simulations of the off-road tire on gravel road under different slip conditions are performed with the commercial software LS-DYNA. The simulation results are basically corresponded with the soil-bin test results in terms of granular terrain deformation and tractive performance parameters versus the slip rates. Finally, the effects of tread pattern, wheel load, and tire inflation pressure on tractive performance of off-road tire on granular terrain are investigated. It indicates that the calibrated finite element method–discrete element method can be an effective tool for studying the tire–granular terrain interaction and predicting the tractive performance of off-road tire on granular terrain.

In order to analyze deformation and stress state of round link chain which it is generated by instant impact for sudden loading between the chains during the working condition, the method of symmetric penalty function was adopted to analyze contact between round link chains; and the finite element software ANSYS LS-DYNA was further used to carry on nonlinear contact analysis, the displacement curves , the stress and deformation with time were gained during the process of impact by simulating the process of the instant impact of chains. The results show that it is circular to the contact area of round link chains and it is the main reasons of damage that the greater stress and deformation of impact is caused when time lasts 0.05s through theoretical analysis and finite element analysis software. The theory equations of load conditions and the method of finite elements can provide a theoretical basis and simulation methods for analyzing the round link chain driving in a variety of different working conditions under the conditions of impact.

Today, the electricity industries are facing new challenges as the market is being liberalized and deregulated in many countries. Electricity storage is undoubtedly a disruptive technology that will play, in the near future, a major role in the fast developing distributed generations network. Indeed, electricity storage has many potential applications: management of the supply and demand of electricity, power quality, integration of renewable sources, improvement of the level of use of the transport and distribution network, etc. Over the years, many storage technologies have been investigated and developed, some have reached the demonstrator level and only a few have become commercially available. The pumped hydro facilities have been successfully storing electricity for more than a century; but today, appropriate locations are seldom found. Electrochemical storage is also an effective means to accumulate electrical energy; among the emerging technologies, the flow batteries are excellent candidates for large stationary storage applications where the vanadium redox flow battery (VRB) distinguishes itself thanks to its competitive cost and simplicity. In this ambitious work that encompasses the domains of electricity, electrochemistry and fluid mechanics, we have proposed a novel multiphysics model of the VRB. This model describes the principles and relations that govern the behaviour of the VRB under any set of operating conditions. Furthermore, this multiphysics model is a powerful means to identify and quantify the sources of losses within the VRB storage system; indeed, one of the purposes of this study is to propose strategies of control and operation for a greater effectiveness of the overall storage system. The electrochemical model is based on the electrochemical principles and the study of the VRB chemistry; this model determines the equilibrium voltage from the vanadium concentrations, and the associated activation, concentration, ohmic and ionic overpotentials. Furthermore, the vanadium concentrations within the tank and the stack are constantly determined as a function of the current and the electrolyte flowrate. A simplified model of the internal loss is also proposed. The electrochemical performance was then established through the simulation of a stand alone system composed of a solar source, a VRB and a load. The model determines the stack voltage, the power flows and the vanadium concentrations over a 24 h period. Furthermore, the model was successfully compared with experimental data through a series of charge and discharge cycles at constant currents. Thereafter, the properties of the electrolyte are briefly investigated: in particular their dependence upon the electrolyte composition. Indeed, the viscosity and the density are important parameters of the mechanical model. In order to analyse the battery performance, a mechanical model has been proposed to determine the mechanical power required to flow the electrolytes. This model based on fluid mechanics has an analytical part that predicts the pressure drop within the pipes and the tanks, and a numerical part. Indeed, the stack geometry is so complex that it can not be described analytically; therefore, a numerical model based on finite element method (FEM) is proposed. Hence, the mechanical power necessary to the battery operation is obtained at any operating conditions. The electrochemical and the mechanical models are finally assembled to form the original multiphysics model of the VRB. This model provides a good insight of the battery operation and offers a powerful means to enhance the battery performance. Indeed, there is at constant current an optimal flowrate that maximizes the efficiency. A second series of charge and discharge cycles has determined the efficiency of different control strategies. Finally, the battery operations at constant power were also discussed in details and an optimal operating point has been highlighted.

Design of patient specific basal dental implant using Finite Element method and Artificial Neural Network technique.

Real-world groundwater modeling deals with heterogeneous and anisotropic aquifer systems. Numerical models, particularly the finite difference and finite element methods, are extensively used for modeling such a complex aquifer system. The finite difference method is an age-old straightforward approach, whereas the finite element method is more idealistic, relatively new, and has emerged as a popular approach. The unique advantages with the finite element method are (i) an irregular-shaped domain can be discretized into elements with a matching boundary, (ii) a node can be connected with the neighboring nodes in any direction. Thus, the finite element analysis allows water/solute to flow more freely toward the surrounding nodes along nodal links. On the other hand, the mathematical formulation of the finite element technique follows a set of rules step by step. Conventionally, this idealistic approach uses shape functions and integration techniques to develop element matrices, which, in turn, are assembled to form the global matrix. This conventional global matrix was found to be inconsistent with the basic partial differential equation representing the mass balance in a nodal domain as a control volume. As a result, the matrix solution, particularly for nonlinear problems (e.g., vadose zone flow, density dependent flow, and so forth) becomes unstable and computationally burdensome. To overcome the limitations of the conventional finite element method for real-world groundwater modeling, a new approach, called the direct-formulation finite element (DFFE) method, has been developed. In this approach, a two-dimensional model domain is discretized into triangular elements. Element matrices are formed directly based on flow principles and material properties of elements without using shape functions and integration process. The DFFE method is robust. The global matrix is consistent, and the solution is stable and efficient. The results obtained from this approach were found in a good agreement with that obtained from analytical and other widely used models.

Few years ago, Lighthill and Whitham (1955) published a lengthy paper dealing with the theory of highway traffic flow .The basic idea in their approach to the problem is that the flow of traffic along a highway is analogous to the flow of a fluid in an open channel or pipe. This point of view replaces a long column of closely spaced discrete moving vehicles with an equivalent continuous moving stream of liquid (e.g. water) or gas (e.g. air). In other words, Lighthill and Whitham analyzed the phenomenon of traffic flow as though it were a problem in fluid mechanics. This approach allows some, though certainly not all, of the physical and mathematical relationships of hydrodynamics and aerodynamics to be utilized in the traffic flow problem. (Bank, p. 272) DOI: http://dx.doi.org/10.3126/jie.v9i1.10681Journal of the Institute of Engineering, Vol. 9, No. 1, pp. 175–181

One of the main concerns in using commercial software for finite element analyses of dam-foundation-reservoir systems is that the simplifying assumptions of the massless foundation are unreliable. In this study, an appropriate direct finite element method is introduced for simulating the mass, radiation damping and wave propagation effect in foundations of dam-foundation-reservoir systems using commercial software ABAQUS. The free-field boundary condition is used for modeling the semi-infinite foundation and radiation damping, which is not a built-in boundary condition in most of the available commercial software for finite element analysis of structures such as ANSYS or ABAQUS and thus needs to be implemented differently. The different mechanism for modeling of the foundation, earthquake input and far-field boundary condition is described. Implementation of the free-field boundary condition in finite element software is verified by comparing it with analytical results. To investigation the feasibility of the proposed method in dam-foundation-reservoir system analysis, a series of analyses is accomplished in a variety of cases and the obtained results are compared with the substructure method by using the EAGD-84 program. Finally, the massed and massless foundation results are compared and it is concluded that the massless foundation approach leads to the overestimation of the displacements and stresses within the dam body.

This paper is concerned with the exposition of finite element applications to combustion problems. The subject of computational fluid dynamics, including combustion calculations, has long been dominated by finite differences. Recently, however, the finite element method has emerged as a potential candidate for computational modelling in fluid mechanics. It is well known that reactive fluids with combustion present additional complications because of disparity in reaction rates commonly referred to as ‘stiff’. The present paper reviews basic questions arising from combustion problems in applications of finite element techniques to the solution of problems associated with chemical kinetics, diffusion, waves, convection, etc. Finally, an example of a hydrogen‐oxygen reaction is presented for practical applications. Extension to the finite element modelling of turbulence, sprays, boundary layers, shock waves, etc. in combustion must await significant developments of numerical strategies associated with a more complete understanding of physical phenomena and chemical kinetics.