An Energy Based Numerical Approach to Phase Change Problems
DEFF Research Database (Denmark)
Hauggaard-Nielsen, Anders Boe; Damkilde, Lars; Krenk, Steen
1996-01-01
Phase change problems, occurring e.g. in melting, casting and freezing processes, are often characterized by a very narrow transition zone with very lareg changes in heat capacity and conductivity. This leads to problems in numerical procedures, where the transition zone propagates through a mesh...... in the mid-point of the current time step and full energy balance is restored in each iteration by adjusting the local temperature. Examples demonstrate improved accuracy, a reduction of the numerical disturbances introduced by the passage of the transition zone and a smaller number of timesteps needed...
Energy-based numerical models for assessment of soil liquefaction
Directory of Open Access Journals (Sweden)
Amir Hossein Alavi
2012-07-01
Full Text Available This study presents promising variants of genetic programming (GP, namely linear genetic programming (LGP and multi expression programming (MEP to evaluate the liquefaction resistance of sandy soils. Generalized LGP and MEP-based relationships were developed between the strain energy density required to trigger liquefaction (capacity energy and the factors affecting the liquefaction characteristics of sands. The correlations were established based on well established and widely dispersed experimental results obtained from the literature. To verify the applicability of the derived models, they were employed to estimate the capacity energy values of parts of the test results that were not included in the analysis. The external validation of the models was verified using statistical criteria recommended by researchers. Sensitivity and parametric analyses were performed for further verification of the correlations. The results indicate that the proposed correlations are effectively capable of capturing the liquefaction resistance of a number of sandy soils. The developed correlations provide a significantly better prediction performance than the models found in the literature. Furthermore, the best LGP and MEP models perform superior than the optimal traditional GP model. The verification phases confirm the efficiency of the derived correlations for their general application to the assessment of the strain energy at the onset of liquefaction.
Numerical Study on Stability of Rock Slope Based on Energy Method
Gao, Wei; Wang, Xu; Dai, Shuang; Chen, Dongliang
2016-01-01
To solve the main shortcoming of numerical method for analysis of the stability of rock slope, such as the selection the convergence condition for the strength reduction method, one method based on the minimum energy dissipation rate is proposed. In the new method, the basic principle of fractured rock slope failure, that is, the process of the propagation and coalescence for cracks in rock slope, is considered. Through analysis of one mining rock slope in western China, this new method is ve...
Energy Technology Data Exchange (ETDEWEB)
Rabern, D.A.
1991-12-31
Three-dimensional numerical simulations were performed to determine the effect of an asymmetric base pressure on kinetic energy projectiles during launch. A matrix of simulations was performed in two separate launch environments. One launch environment represented a severe lateral load environment, while the other represented a nonsevere lateral load environment based on the gun tube straightness. The orientation of the asymmetric pressure field, its duration, the projectile`s initial position, and the tube straightness were altered to determine the effects of each parameter. The pressure asymmetry translates down the launch tube to exit parameters and is washed out by tube profile. Results from the matrix of simulations are presented.
Energy Technology Data Exchange (ETDEWEB)
Rabern, D.A.
1991-01-01
Three-dimensional numerical simulations were performed to determine the effect of an asymmetric base pressure on kinetic energy projectiles during launch. A matrix of simulations was performed in two separate launch environments. One launch environment represented a severe lateral load environment, while the other represented a nonsevere lateral load environment based on the gun tube straightness. The orientation of the asymmetric pressure field, its duration, the projectile's initial position, and the tube straightness were altered to determine the effects of each parameter. The pressure asymmetry translates down the launch tube to exit parameters and is washed out by tube profile. Results from the matrix of simulations are presented.
Directory of Open Access Journals (Sweden)
Deepa Devasenapathy
2015-01-01
Full Text Available The traffic in the road network is progressively increasing at a greater extent. Good knowledge of network traffic can minimize congestions using information pertaining to road network obtained with the aid of communal callers, pavement detectors, and so on. Using these methods, low featured information is generated with respect to the user in the road network. Although the existing schemes obtain urban traffic information, they fail to calculate the energy drain rate of nodes and to locate equilibrium between the overhead and quality of the routing protocol that renders a great challenge. Thus, an energy-efficient cluster-based vehicle detection in road network using the intention numeration method (CVDRN-IN is developed. Initially, sensor nodes that detect a vehicle are grouped into separate clusters. Further, we approximate the strength of the node drain rate for a cluster using polynomial regression function. In addition, the total node energy is estimated by taking the integral over the area. Finally, enhanced data aggregation is performed to reduce the amount of data transmission using digital signature tree. The experimental performance is evaluated with Dodgers loop sensor data set from UCI repository and the performance evaluation outperforms existing work on energy consumption, clustering efficiency, and node drain rate.
Toivanen, Elias A; Losilla, Sergio A; Sundholm, Dage
2015-12-21
Algorithms and working expressions for a grid-based fast multipole method (GB-FMM) have been developed and implemented. The computational domain is divided into cubic subdomains, organized in a hierarchical tree. The contribution to the electrostatic interaction energies from pairs of neighboring subdomains is computed using numerical integration, whereas the contributions from further apart subdomains are obtained using multipole expansions. The multipole moments of the subdomains are obtained by numerical integration. Linear scaling is achieved by translating and summing the multipoles according to the tree structure, such that each subdomain interacts with a number of subdomains that are almost independent of the size of the system. To compute electrostatic interaction energies of neighboring subdomains, we employ an algorithm which performs efficiently on general purpose graphics processing units (GPGPU). Calculations using one CPU for the FMM part and 20 GPGPUs consisting of tens of thousands of execution threads for the numerical integration algorithm show the scalability and parallel performance of the scheme. For calculations on systems consisting of Gaussian functions (α = 1) distributed as fullerenes from C20 to C720, the total computation time and relative accuracy (ppb) are independent of the system size.
Kabuth, Alina; Dahmke, Andreas; Hagrey, Said Attia al; Berta, Márton; Dörr, Cordula; Koproch, Nicolas; Köber, Ralf; Köhn, Daniel; Nolde, Michael; Tilmann Pfeiffer, Wolf; Popp, Steffi; Schwanebeck, Malte; Bauer, Sebastian
2016-04-01
Within the framework of the transition to renewable energy sources ("Energiewende"), the German government defined the target of producing 60 % of the final energy consumption from renewable energy sources by the year 2050. However, renewable energies are subject to natural fluctuations. Energy storage can help to buffer the resulting time shifts between production and demand. Subsurface geological structures provide large potential capacities for energy stored in the form of heat or gas on daily to seasonal time scales. In order to explore this potential sustainably, the possible induced effects of energy storage operations have to be quantified for both specified normal operation and events of failure. The ANGUS+ project therefore integrates experimental laboratory studies with numerical approaches to assess subsurface energy storage scenarios and monitoring methods. Subsurface storage options for gas, i.e. hydrogen, synthetic methane and compressed air in salt caverns or porous structures, as well as subsurface heat storage are investigated with respect to site prerequisites, storage dimensions, induced effects, monitoring methods and integration into spatial planning schemes. The conceptual interdisciplinary approach of the ANGUS+ project towards the integration of subsurface energy storage into a sustainable subsurface planning scheme is presented here, and this approach is then demonstrated using the examples of two selected energy storage options: Firstly, the option of seasonal heat storage in a shallow aquifer is presented. Coupled thermal and hydraulic processes induced by periodic heat injection and extraction were simulated in the open-source numerical modelling package OpenGeoSys. Situations of specified normal operation as well as cases of failure in operational storage with leaking heat transfer fluid are considered. Bench-scale experiments provided parameterisations of temperature dependent changes in shallow groundwater hydrogeochemistry. As a
Directory of Open Access Journals (Sweden)
Zahid Suleman
2011-07-01
Full Text Available This research paper describes design and analysis of power extracting unit of an onshore OWC (Oscillating Water Column based wave energy power plant of capacity about 100 kilowatts. The OWC is modeled as solid piston of a reciprocating pump. The power extracting unit is designed analytically by using the theory of reciprocating pumps and principles of fluid mechanics. Pro-E and ANSYS workbench softwares are used to verify the analytical design. The analytical results of the flow velocity in the turbine duct are compared with the simulation results. The results are found to be in good agreement with each other. The results achieved by this research would finally assist in the overall design of the power plant which is the ultimate goal of this research work.
Concrete thermal energy storage for steam generation: A numerical investigation
DEFF Research Database (Denmark)
Singh, Shobhana; Sørensen, Kim
2017-01-01
Establishing enhancement methods to develop cost-effective thermal energy storage technology requires a detailed analysis. In this paper, a numerical investigation of the concrete based thermal energy storage system is carried out. The storage system consists of a heat transfer fluid flowing insi...
High energy gravitational scattering: a numerical study
Marchesini, Giuseppe
2008-01-01
The S-matrix in gravitational high energy scattering is computed from the region of large impact parameters b down to the regime where classical gravitational collapse is expected to occur. By solving the equation of an effective action introduced by Amati, Ciafaloni and Veneziano we find that the perturbative expansion around the leading eikonal result diverges at a critical value signalling the onset of a new regime. We then discuss the main features of our explicitly unitary S-matrix down to the Schwarzschild's radius R=2G s^(1/2), where it diverges at a critical value b ~ 2.22 R of the impact parameter. The nature of the singularity is studied with particular attention to the scaling behaviour of various observables at the transition. The numerical approach is validated by reproducing the known exact solution in the axially symmetric case to high accuracy.
Numerical and experimental design of coaxial shallow geothermal energy systems
Raghavan, Niranjan
Geothermal Energy has emerged as one of the front runners in the energy race because of its performance efficiency, abundance and production competitiveness. Today, geothermal energy is used in many regions of the world as a sustainable solution for decreasing dependence on fossil fuels and reducing health hazards. However, projects related to geothermal energy have not received their deserved recognition due to lack of computational tools associated with them and economic misconceptions related to their installation and functioning. This research focuses on numerical and experimental system design analysis of vertical shallow geothermal energy systems. The driving force is the temperature difference between a finite depth beneath the earth and its surface stimulates continuous exchange of thermal energy from sub-surface to the surface (a geothermal gradient is set up). This heat gradient is captured by the circulating refrigerant and thus, tapping the geothermal energy from shallow depths. Traditionally, U-bend systems, which consist of two one-inch pipes with a U-bend connector at the bottom, have been widely used in geothermal applications. Alternative systems include coaxial pipes (pipe-in-pipe) that are the main focus of this research. It has been studied that coaxial pipes have significantly higher thermal performance characteristics than U-bend pipes, with comparative production and installation costs. This makes them a viable design upgrade to the traditional piping systems. Analytical and numerical heat transfer analysis of the coaxial system is carried out with the help of ABAQUS software. It is tested by varying independent parameters such as materials, soil conditions and effect of thermal contact conductance on heat transfer characteristics. With the above information, this research aims at formulating a preliminary theoretical design setup for an experimental study to quantify and compare the heat transfer characteristics of U-bend and coaxial
Frenod, Emmanuel
2013-01-01
In this note, a classification of Homogenization-Based Numerical Methods and (in particular) of Numerical Methods that are based on the Two-Scale Convergence is done. In this classification stand: Direct Homogenization-Based Numerical Methods; H-Measure-Based Numerical Methods; Two-Scale Numerical Methods and TSAPS: Two-Scale Asymptotic Preserving Schemes.
Numerical Modeling of a Wave Energy Point Absorber
DEFF Research Database (Denmark)
Hernandez, Lorenzo Banos; Frigaard, Peter; Kirkegaard, Poul Henning
2009-01-01
The present study deals with numerical modelling of the Wave Star Energy WSE device. Hereby, linear potential theory is applied via a BEM code on the wave hydrodynamics exciting the floaters. Time and frequency domain solutions of the floater response are determined for regular and irregular seas....... Furthermore, these results are used to estimate the power and the energy absorbed by a single oscillating floater. Finally, a latching control strategy is analysed in open-loop configuration for energy maximization....
Finite Element Based Viscous Numerical Wave Flume
Directory of Open Access Journals (Sweden)
Jianmin Qin
2013-01-01
Full Text Available A two-dimensional numerical wave flume (NWF for viscous fluid flows with free surface is developed in this work. It is based on the upwind finite element solutions of Navier-Stokes equations, CLEAR-volume of fluid method for free surface capture, internal wave maker for wave generation, and sponge layer for wave absorbing. The wave generation and absorption by prescribing velocity boundary conditions along inlet and radiation boundary condition along outlet are also incorporated. The numerical model is validated against several benchmarks, including dam-breaking flow, liquid sloshing in baffled tank, linear water wave propagation and reflection from vertical wall, nonlinear solitary wave fission over sharp step, and wave-induced fluid resonance in narrow gap confined by floating structures. The comparisons with available experimental data, numerical results, and theoretical solutions confirm that the present numerical wave flume has good performance in dealing with complex interface flows and water wave interaction with structures.
Numerical modelling of the HAB Energy Buoy: Stage 1
DEFF Research Database (Denmark)
Kurniawan, Adi
2017-01-01
. The model is further able to give an estimate of the power production of the device in a given wave climate as well as other statistical estimates of the device motions and loads. The performance of different device shapes and dimensions has been evaluated, where displacement limits appropriate for each......This report presents the results of the first stage of the project "Numerical modelling of the HAB Energy Buoy". The objectives of this stage are to develop a numerical model of the HAB Energy Buoy, a self-reacting wave energy device consisting of two heaving bodies, and to investigate a number...... of variations of the device geometry in order to arrive at a design optimized for the target deployment site. The findings will be used as a basis to inform planned small-scale wave tank tests. A review of literature on self-reacting wave energy devices consisting of two heaving bodies has been conducted...
Energy Technology Data Exchange (ETDEWEB)
Maglevanny, I.I., E-mail: sianko@list.ru [Volgograd State Social Pedagogical University, 27 Lenin Avenue, Volgograd 400131 (Russian Federation); Smolar, V.A. [Volgograd State Technical University, 28 Lenin Avenue, Volgograd 400131 (Russian Federation)
2016-01-15
We introduce a new technique of interpolation of the energy-loss function (ELF) in solids sampled by empirical optical spectra. Finding appropriate interpolation methods for ELFs poses several challenges. The sampled ELFs are usually very heterogeneous, can originate from various sources thus so called “data gaps” can appear, and significant discontinuities and multiple high outliers can be present. As a result an interpolation based on those data may not perform well at predicting reasonable physical results. Reliable interpolation tools, suitable for ELF applications, should therefore satisfy several important demands: accuracy and predictive power, robustness and computational efficiency, and ease of use. We examined the effect on the fitting quality due to different interpolation schemes with emphasis on ELF mesh optimization procedures and we argue that the optimal fitting should be based on preliminary log–log scaling data transforms by which the non-uniformity of sampled data distribution may be considerably reduced. The transformed data are then interpolated by local monotonicity preserving Steffen spline. The result is a piece-wise smooth fitting curve with continuous first-order derivatives that passes through all data points without spurious oscillations. Local extrema can occur only at grid points where they are given by the data, but not in between two adjacent grid points. It is found that proposed technique gives the most accurate results and also that its computational time is short. Thus, it is feasible using this simple method to address practical problems associated with interaction between a bulk material and a moving electron. A compact C++ implementation of our algorithm is also presented.
Numerical analysis of the Black Sea energy budget in 2011
Demyshev, S. G.; Dymova, O. A.
2017-09-01
The paper analyzes the results of the annual-averaged and seasonal-averaged variability of the Black Sea energetics in 2011. Energetic features were computed by equations describing the change rate of the kinetic and potential energy. They corresponded precisely to the finite-difference equations of the ocean model developed in the Marine Hydrophysical Institute of the Russian Academy of Sciences. A numerical experiment was run with a horizontal resolution of 1.6 km and took into account the real atmospheric forcing SKIRON for 2011. It was discovered that on average over the year the most significant components of the integral energy budget were the wind work, the dissipation due to friction, and the change of potential energy due to vertical diffusion. Seasonal variability of energy fluxes was determined by the contribution from wind and dissipation due to friction in the autumn-winter period. As a result, the vertical mixing processes enhanced and the RIM Current got stronger. In the spring and summer seasons the main energy processes were the buoyancy work and vertical turbulent diffusion due to increase in the vertical density gradient.
Supporting Current Energy Conversion Projects through Numerical Modeling
James, S. C.; Roberts, J.
2016-02-01
The primary goals of current energy conversion (CEC) technology being developed today are to optimize energy output and minimize environmental impact. CEC turbines generate energy from tidal and current systems and create wakes that interact with turbines located downstream of a device. The placement of devices can greatly influence power generation and structural reliability. CECs can also alter the environment surrounding the turbines, such as flow regimes, sediment dynamics, and water quality. These alterations pose potential stressors to numerous environmental receptors. Software is needed to investigate specific CEC sites to simulate power generation and hydrodynamic responses of a flow through a CEC turbine array so that these potential impacts can be evaluated. Moreover, this software can be used to optimize array layouts that yield the least changes to the environmental (i.e., hydrodynamics, sediment dynamics, and water quality). Through model calibration exercises, simulated wake profiles and turbulence intensities compare favorably to the experimental data and demonstrate the utility and accuracy of a fast-running tool for future siting and analysis of CEC arrays in complex domains. The Delft3D modeling tool facilitates siting of CEC projects through optimization of array layouts and evaluation of potential environmental effect all while provide a common "language" for academics, industry, and regulators to be able to discuss the implications of marine renewable energy projects. Given the enormity of any full-scale marine renewable energy project, it necessarily falls to modeling to evaluate how array operations must be addressed in an environmental impact statement in a way that engenders confidence in the assessment of the CEC array to minimize environmental effects.
Directory of Open Access Journals (Sweden)
M. Boumaza
2015-07-01
Full Text Available Transient convection heat transfer is of fundamental interest in many industrial and environmental situations, as well as in electronic devices and security of energy systems. Transient fluid flow problems are among the more difficult to analyze and yet are very often encountered in modern day technology. The main objective of this research project is to carry out a theoretical and numerical analysis of transient convective heat transfer in vertical flows, when the thermal field is due to different kinds of variation, in time and space of some boundary conditions, such as wall temperature or wall heat flux. This is achieved by the development of a mathematical model and its resolution by suitable numerical methods, as well as performing various sensitivity analyses. These objectives are achieved through a theoretical investigation of the effects of wall and fluid axial conduction, physical properties and heat capacity of the pipe wall on the transient downward mixed convection in a circular duct experiencing a sudden change in the applied heat flux on the outside surface of a central zone.
Energy-conserving semi-discretizations and spurious numerical reflections
J.E. Frank (Jason); S. Reich
2006-01-01
textabstractWe consider energy-conserving semi-discretizations of linear wave equations on nonuniform grids. Specifically we study explicit and implicit skew-adjoint finite difference methods, based on the assumption of an underlying smooth mapping from a uniform grid, applied to the first and
Navas-Montilla, A.; Murillo, J.
2017-07-01
When designing a numerical scheme for the resolution of conservation laws, the selection of a particular source term discretization (STD) may seem irrelevant whenever it ensures convergence with mesh refinement, but it has a decisive impact on the solution. In the framework of the Shallow Water Equations (SWE), well-balanced STD based on quiescent equilibrium are unable to converge to physically based solutions, which can be constructed considering energy arguments. Energy based discretizations can be designed assuming dissipation or conservation, but in any case, the STD procedure required should not be merely based on ad hoc approximations. The STD proposed in this work is derived from the Generalized Hugoniot Locus obtained from the Generalized Rankine Hugoniot conditions and the Integral Curve across the contact wave associated to the bed step. In any case, the STD must allow energy-dissipative solutions: steady and unsteady hydraulic jumps, for which some numerical anomalies have been documented in the literature. These anomalies are the incorrect positioning of steady jumps and the presence of a spurious spike of discharge inside the cell containing the jump. The former issue can be addressed by proposing a modification of the energy-conservative STD that ensures a correct dissipation rate across the hydraulic jump, whereas the latter is of greater complexity and cannot be fixed by simply choosing a suitable STD, as there are more variables involved. The problem concerning the spike of discharge is a well-known problem in the scientific community, also known as slowly-moving shock anomaly, it is produced by a nonlinearity of the Hugoniot locus connecting the states at both sides of the jump. However, it seems that this issue is more a feature than a problem when considering steady solutions of the SWE containing hydraulic jumps. The presence of the spurious spike in the discharge has been taken for granted and has become a feature of the solution. Even though
Linearly decoupled energy-stable numerical methods for multi-component two-phase compressible flow
Kou, Jisheng
2017-12-06
In this paper, for the first time we propose two linear, decoupled, energy-stable numerical schemes for multi-component two-phase compressible flow with a realistic equation of state (e.g. Peng-Robinson equation of state). The methods are constructed based on the scalar auxiliary variable (SAV) approaches for Helmholtz free energy and the intermediate velocities that are designed to decouple the tight relationship between velocity and molar densities. The intermediate velocities are also involved in the discrete momentum equation to ensure a consistency relationship with the mass balance equations. Moreover, we propose a component-wise SAV approach for a multi-component fluid, which requires solving a sequence of linear, separate mass balance equations. We prove that the methods have the unconditional energy-dissipation feature. Numerical results are presented to verify the effectiveness of the proposed methods.
Numerical optimization of Wells turbine for wave energy extraction
Directory of Open Access Journals (Sweden)
Paresh Halder
2017-01-01
Full Text Available The present work focuses multi-objective optimization of blade sweep for a Wells turbine. The blade-sweep parameters at the mid and the tip sections are selected as design variables. The peak-torque coefficient and the corresponding efficiency are the objective functions, which are maximized. The numerical analysis has been carried out by solving 3D RANS equations based on k-w SST turbulence model. Nine design points are selected within a design space and the simulations are run. Based on the computational results, surrogate-based weighted average models are constructed and the population based multi-objective evolutionary algorithm gave Pareto optimal solutions. The peak-torque coefficient and the corresponding efficiency are enhanced, and the results are analysed using CFD simulations. Two extreme designs in the Pareto solutions show that the peak-torque-coefficient is increased by 28.28% and the corresponding efficiency is decreased by 13.5%. A detailed flow analysis shows the separation phenomena change the turbine performance.
Correlations of seismic motions and energy distributions: numerical results
Carbajal-Romero, Manuel; Pineda-León, Ernesto; Ávila-Carrera, Rafael; Efraín Rodríguez-Sánchez, José; Rodríguez-Castellanos, Alejandro; José Sánchez-Sesma, Francisco
2017-12-01
It is well known that the response of a medium at a specified load is given by the Green’s function, which can be seen as an intrinsic property of the medium. However, in many situations, the Green’s function is not available. In seismology, the Green’s function is the fundamental characteristic of the medium where seismic waves propagate and this function can be recovered experimentally by correlations of seismic movements. Furthermore, in a two-dimensional infinite medium, waves (P- and SV-waves) propagate with fixed amounts of energy. These amounts of energy, associated with the P- and SV-waves, vary with the type of medium, which is characterized by the Poisson’s ratio. Additionally, the theoretical energy distribution has been reported in the literature as a function of the elastic properties of the medium, specifically its Poisson’s ratio. In this paper, an approach to calculate the energy distributions associated with P- and SV-waves is provided. This approach is based on the interpretation of theoretical seismograms and recovered seismograms by means of correlations. This approach has important implications because by the results obtained it is possible to validate if a correlation of seismic movements is close to fully validated theoretical values. This article shows some examples and cases varying types of materials, characterized by its Poisson’s ratio.
Numerical Analysis of a Large Floating Wave Energy Converter with Adjustable Structural Geometry
DEFF Research Database (Denmark)
Ferri, Francesco; Pecher, Arthur Francois Serge; Kofoed, Jens Peter
2015-01-01
The current cost of energy (CoE) from wave energy converters (WECs) is still significantly higher than other renewable energy resources, thus the sector has not yet reached a competitive level. WECs have a relative small turnover compared to the high capital cost, which to a large extent is driven...... by the structural loads in extreme conditions. TheWeptos is a large floating WEC, with multiple absorbers, which has proven to be a serious candidate for the renewable energy market, due to both relevant power performance and reduced cost if compared with other WECs. The scope of this article is to compare two...... different configurations of the Weptos machine, using the cost of energy (CoE) as a base of comparison. The numerical results are obtained via a multi-body analysis carried out in frequency domain....
Comparative numerical and experimental study of two combined wind and wave energy concepts
Directory of Open Access Journals (Sweden)
Zhen Gao
2016-01-01
Full Text Available With a successful and rapid development of offshore wind industry and increased research activities on wave energy conversion in recent years, there is an interest in investigating the technological and economic feasibility of combining offshore wind turbines (WTs with wave energy converters (WECs. In the EU FP7 MARINA Platform project, three floating combined concepts, namely the spar torus combination (STC, the semi-submersible flap combination (SFC and the oscillating water column (OWC array with a wind turbine, were selected and studied in detail by numerical and experimental methods. This paper summarizes the numerical modeling and analysis of the two concepts: STC and SFC, the model tests at a 1:50 scale under simultaneous wave and wind excitation, as well as the comparison between the numerical and experimental results. Both operational and survival wind and wave conditions were considered. The numerical analysis was based on a time-domain global model using potential flow theory for hydrodynamics and blade element momentum theory (for SFC or simplified thrust force model (for STC for aerodynamics. Different techniques for model testing of combined wind and wave concepts were discussed with focus on modeling of wind turbines by disk or redesigned small-scale rotor and modeling of power take-off (PTO system for wave energy conversion by pneumatic damper or hydraulic rotary damper. In order to reduce the uncertainty due to scaling, the numerical analysis was performed at model scale and both the numerical and experimental results were then up-scaled to full scale for comparison. The comparison shows that the current numerical model can well predict the responses (motions, PTO forces, power production of the combined concepts for most of the cases. However, the linear hydrodynamic model is not adequate for the STC concept in extreme wave conditions with the torus fixed to the spar at the mean water level for which the wave slamming on the
Experimental and numerical investigation of a packed-bed thermal energy storage device
Yang, Bei; Wang, Yan; Bai, Fengwu; Wang, Zhifeng
2017-06-01
This paper presents a pilot-scale setup built to study a packed bed thermal energy storage device based on ceramic balls randomly poured into a cylindrical tank while using air as heat transfer fluid. Temperature distribution of ceramic balls throughout the packed bed is investigated both experimentally and numerically. Method of characteristic is adopted to improve the numerical computing efficiency, and mesh independence is verified to guarantee the accuracy of numerical solutions and the economy of computing time cost at the same time. Temperature in tests is as high as over 600 °C, and modeling prediction shows good agreements with experimental results under various testing conditions when heat loss is included and thermal properties of air are considered as temperature dependent.
Henle, James M.
This pamphlet consists of 17 brief chapters, each containing a discussion of a numeration system and a set of problems on the use of that system. The numeration systems used include Egyptian fractions, ordinary continued fractions and variants of that method, and systems using positive and negative bases. The book is informal and addressed to…
SMD-based numerical stochastic perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Dalla Brida, Mattia [Universita di Milano-Bicocca, Dipartimento di Fisica, Milan (Italy); INFN, Sezione di Milano-Bicocca (Italy); Luescher, Martin [CERN, Theoretical Physics Department, Geneva (Switzerland); AEC, Institute for Theoretical Physics, University of Bern (Switzerland)
2017-05-15
The viability of a variant of numerical stochastic perturbation theory, where the Langevin equation is replaced by the SMD algorithm, is examined. In particular, the convergence of the process to a unique stationary state is rigorously established and the use of higher-order symplectic integration schemes is shown to be highly profitable in this context. For illustration, the gradient-flow coupling in finite volume with Schroedinger functional boundary conditions is computed to two-loop (i.e. NNL) order in the SU(3) gauge theory. The scaling behaviour of the algorithm turns out to be rather favourable in this case, which allows the computations to be driven close to the continuum limit. (orig.)
Numerical Modeling and Experimental Testing of a Wave Energy Converter
DEFF Research Database (Denmark)
Zurkinden, Andrew Stephen; Kramer, Morten; Ferri, Francesco
numerical values for comparison with the experimental test results which were carried out in the same time. It is for this reason why Chapter 4 does consist exclusively of numerical values. Experimental values and measured time series of wave elevations have been used throughout the report in order to a...
Performance of Numerical Boundary Condition based on Active Wave Absorption
DEFF Research Database (Denmark)
Troch, Peter; De Rouck, Julien; Frigaard, Peter
2001-01-01
The performance of a new active wave generating-absorbing boundary condition for a numerical model based on the Volume Of Fluid (VOF) method for tracking free surfaces is presented.......The performance of a new active wave generating-absorbing boundary condition for a numerical model based on the Volume Of Fluid (VOF) method for tracking free surfaces is presented....
Tensor numerical methods in quantum chemistry: from Hartree-Fock to excitation energies.
Khoromskaia, Venera; Khoromskij, Boris N
2015-12-21
We resume the recent successes of the grid-based tensor numerical methods and discuss their prospects in real-space electronic structure calculations. These methods, based on the low-rank representation of the multidimensional functions and integral operators, first appeared as an accurate tensor calculus for the 3D Hartree potential using 1D complexity operations, and have evolved to entirely grid-based tensor-structured 3D Hartree-Fock eigenvalue solver. It benefits from tensor calculation of the core Hamiltonian and two-electron integrals (TEI) in O(n log n) complexity using the rank-structured approximation of basis functions, electron densities and convolution integral operators all represented on 3D n × n × n Cartesian grids. The algorithm for calculating TEI tensor in a form of the Cholesky decomposition is based on multiple factorizations using algebraic 1D "density fitting" scheme, which yield an almost irreducible number of product basis functions involved in the 3D convolution integrals, depending on a threshold ε > 0. The basis functions are not restricted to separable Gaussians, since the analytical integration is substituted by high-precision tensor-structured numerical quadratures. The tensor approaches to post-Hartree-Fock calculations for the MP2 energy correction and for the Bethe-Salpeter excitation energies, based on using low-rank factorizations and the reduced basis method, were recently introduced. Another direction is towards the tensor-based Hartree-Fock numerical scheme for finite lattices, where one of the numerical challenges is the summation of electrostatic potentials of a large number of nuclei. The 3D grid-based tensor method for calculation of a potential sum on a L × L × L lattice manifests the linear in L computational work, O(L), instead of the usual O(L(3) log L) scaling by the Ewald-type approaches.
High Performance Numerical Computing for High Energy Physics: A New Challenge for Big Data Science
Directory of Open Access Journals (Sweden)
Florin Pop
2014-01-01
Full Text Available Modern physics is based on both theoretical analysis and experimental validation. Complex scenarios like subatomic dimensions, high energy, and lower absolute temperature are frontiers for many theoretical models. Simulation with stable numerical methods represents an excellent instrument for high accuracy analysis, experimental validation, and visualization. High performance computing support offers possibility to make simulations at large scale, in parallel, but the volume of data generated by these experiments creates a new challenge for Big Data Science. This paper presents existing computational methods for high energy physics (HEP analyzed from two perspectives: numerical methods and high performance computing. The computational methods presented are Monte Carlo methods and simulations of HEP processes, Markovian Monte Carlo, unfolding methods in particle physics, kernel estimation in HEP, and Random Matrix Theory used in analysis of particles spectrum. All of these methods produce data-intensive applications, which introduce new challenges and requirements for ICT systems architecture, programming paradigms, and storage capabilities.
Directory of Open Access Journals (Sweden)
A. YAZID MALIKI
2017-05-01
Full Text Available OBREC is the latest innovation of overtopping wave energy converter (WEC which is coalesced with the rubble mound breakwaters. The acquisition of wave overtopping in a front reservoir and consequently releasing process through turbine is the concept of energy production in OBREC. The physical scale model studies of overtopping discharge of the OBREC have recently been done by previous researcher in wave flume at Aalborg University. This paper demonstrates the overtopping behavior of OBREC device using a VOF method with capabilities to solve RANS equation in the numerical suite Flow3D. The purpose of this research is to validate the overtopping discharge performance of the numerical model against the experiments of the OBREC. Based on the observation, the results have shown a good agreement between the validation and physical experiment.
Energy Technology Data Exchange (ETDEWEB)
Azadeh, A.; Amalnick, M.S.; Ghaderi, S.F.; Asadzadeh, S.M. [Department of Industrial Engineering, Faculty of Engineering, Center of Excellence for Intelligent Experimental Mechanics, Research Institute of Energy Management and Planning, P.O. Box 14178-43111, University of Tehran (Iran); Department of Engineering Optimization Research, Faculty of Engineering, Center of Excellence for Intelligent Experimental Mechanics, Research Institute of Energy Management and Planning, P.O. Box 14178-43111, University of Tehran (Iran)
2007-07-15
This paper introduces an integrated approach based on data envelopment analysis (DEA), principal component analysis (PCA) and numerical taxonomy (NT) for total energy efficiency assessment and optimization in energy intensive manufacturing sectors. Total energy efficiency assessment and optimization of the proposed approach considers structural indicators in addition conventional consumption and manufacturing sector output indicators. The validity of the DEA model is verified and validated by PCA and NT through Spearman correlation experiment. Moreover, the proposed approach uses the measure-specific super-efficiency DEA model for sensitivity analysis to determine the critical energy carriers. Four energy intensive manufacturing sectors are discussed in this paper: iron and steel, pulp and paper, petroleum refining and cement manufacturing sectors. To show superiority and applicability, the proposed approach has been applied to refinery sub-sectors of some OECD (Organization for Economic Cooperation and Development) countries. This study has several unique features which are: (1) a total approach which considers structural indicators in addition to conventional energy efficiency indicators; (2) a verification and validation mechanism for DEA by PCA and NT and (3) utilization of DEA for total energy efficiency assessment and consumption optimization of energy intensive manufacturing sectors. (author)
Numerical modeling of Thermal Response Tests in Energy Piles
Franco, A.; Toledo, M.; Moffat, R.; Herrera, P. A.
2013-05-01
conductivity of the soil is the most determinant parameter that affects the estimated thermal conductivity. For example, we observed differences of up to 50% from the expected value at the end of 100 hours of simulation for values of thermal conductivity of the soil in the range of 1 to 6 W/mK. Additionally, we observed that the results of the synthetic TRT depend upon several other parameters such as the boundary conditions used to model the interaction of the top face of the pile with the surrounding media. For example, Simulations with a constant temperature boundary condition tended to overestimate the total thermal conductivity of the whole system. This analysis demonstrates that numerical modeling is a useful tool to model energy pile systems and to interpret and design tests to evaluate their performance. Furthermore, it also reveals that the results of thermal response tests interpreted with analytical models must be evaluated with care for the assessment of the potential of low enthalpy systems, because their results depend upon a variety of factors which are neglected in the analytical models.
Acoustic energy harvesting based on multilateral metasurfaces
Qi, Shuibao; Assouar, Badreddine
2017-12-01
We theoretically and numerically report on an innovative acoustic energy harvester based on acoustic multilateral metasurfaces and a piezoelectric bimorph. The coiling-up-space concept realized by labyrinthine units is applied to achieve the desired phase profiles for the acoustic focusing and energy confinement. The acoustic energy confined by the metasurfaces from a point source is converted into electrical energy by a structured piezoelectric bimorph. Numerical simulations and theoretical analysis evidenced that the output voltage and power drastically increase with the sides of the multilateral metasurface energy harvesting system. Maximum output voltage and power 52 and 407 times higher than those under the case without metasurfaces are achieved with enclosed multilateral metasurface design.
A Numerical and Graphical Review of Energy Storage Technologies
Directory of Open Access Journals (Sweden)
Siraj Sabihuddin
2014-12-01
Full Text Available More effective energy production requires a greater penetration of storage technologies. This paper takes a looks at and compares the landscape of energy storage devices. Solutions across four categories of storage, namely: mechanical, chemical, electromagnetic and thermal storage are compared on the basis of energy/power density, specific energy/power, efficiency, lifespan, cycle life, self-discharge rates, capital energy/power costs, scale, application, technical maturity as well as environmental impact. It’s noted that virtually every storage technology is seeing improvements. This paper provides an overview of some of the problems with existing storage systems and identifies some key technologies that hold promise.
Theoretical and numerical study of hydraulic characteristics of orifice energy dissipator
Directory of Open Access Journals (Sweden)
NingHE
2010-06-01
Full Text Available Different factors affecting the efficiency of the orifice energy dissipator were investigated based on a series of theoretical analyses and numerical simulations. The main factors investigated by dimension analysis were identified, including the Reynolds number (Re, the ratio of the orifice diameter to the inner diameter of the pipe ( , and the ratio of distances between orifices to the inner diameter of the pipe ( . Then, numerical simulations were conducted with a two-equation turbulence model. The calculation results show the following: Hydraulic characteristics change dramatically as flow passes through the orifice, with abruptly increasing velocity and turbulent energy, and decreasing pressure. The turbulent energy appears to be low in the middle and high near the pipe wall. For the energy dissipation setup with only one orifice, when Re is smaller than 105, the orifice energy dissipation coefficient K increases rapidly with the increase of Re. When Re is larger than 105, K gradually stabilizes. As increases, K and the length of the recirculation region L1 show similar variation patterns, which inversely vary with . The function curves can be approximated as straight lines. For the energy dissipation model with two orifices, because of different incoming flows at different orifices, the energy dissipation coefficient of the second orifice (K2 is smaller than that of the first. If is less than 5, the K value of the model, depending on the variation of K2, increases with the spacing between two orifices L , and an orifice cannot fulfill its energy dissipation function. If is greater than 5, K2 tends to be steady; thus, the K value of the model gradually stabilizes. Then, the flow fully develops, and L has almost no impact on the value of K.
Directory of Open Access Journals (Sweden)
R. Sorgente
2011-08-01
Full Text Available The spatial and temporal variability of eddy and mean kinetic energy of the Central Mediterranean region has been investigated, from January 2008 to December 2010, by mean of a numerical simulation mainly to quantify the mesoscale dynamics and their relationships with physical forcing. In order to understand the energy redistribution processes, the baroclinic energy conversion has been analysed, suggesting hypotheses about the drivers of the mesoscale activity in this area. The ocean model used is based on the Princeton Ocean Model implemented at 1/32° horizontal resolution. Surface momentum and buoyancy fluxes are interactively computed by mean of standard bulk formulae using predicted model Sea Surface Temperature and atmospheric variables provided by the European Centre for Medium Range Weather Forecast operational analyses. At its lateral boundaries the model is one-way nested within the Mediterranean Forecasting System operational products.
The model domain has been subdivided in four sub-regions: Sardinia channel and southern Tyrrhenian Sea, Sicily channel, eastern Tunisian shelf and Libyan Sea. Temporal evolution of eddy and mean kinetic energy has been analysed, on each of the four sub-regions, showing different behaviours. On annual scales and within the first 5 m depth, the eddy kinetic energy represents approximately the 60 % of the total kinetic energy over the whole domain, confirming the strong mesoscale nature of the surface current flows in this area. The analyses show that the model well reproduces the path and the temporal behaviour of the main known sub-basin circulation features. New mesoscale structures have been also identified, from numerical results and direct observations, for the first time as the Pantelleria Vortex and the Medina Gyre.
The classical kinetic energy decomposition (eddy and mean allowed to depict and to quantify the permanent and fluctuating parts of the circulation in the region, and
Numerical algorithm based on fast convolution for fractional calculus
Directory of Open Access Journals (Sweden)
Chen An
2012-01-01
Full Text Available In this paper, numerical algorithms based on fast convolution for the fractional integral and fractional derivative are proposed. Two examples are also included which show the efficiency of the derived method.
Hydrogen based energy storage for solar energy systems
Energy Technology Data Exchange (ETDEWEB)
Vanhanen, J.P.; Hagstroem, M.T.; Lund, P.H. [Helsinki Univ. of Technology, Otaniemi (Finland). Dept. of Engineering Physics and Mathematics; Leppaenen, J.R.; Nieminen, J.P. [Neste Oy (Finland)
1998-12-31
Hydrogen based energy storage options for solar energy systems was studied in order to improve their overall performance. A 1 kW photovoltaic hydrogen (PV-H2) pilot-plant and commercial prototype were constructed and a numerical simulation program H2PHOTO for system design and optimisation was developed. Furthermore, a comprehensive understanding of conversion (electrolysers and fuel cells) and storage (metal hydrides) technologies was acquired by the project partners. The PV-H{sub 2} power system provides a self-sufficient solution for applications in remote locations far from electric grids and maintenance services. (orig.)
Parametric pendulum based wave energy converter
Yurchenko, Daniil; Alevras, Panagiotis
2018-01-01
The paper investigates the dynamics of a novel wave energy converter based on the parametrically excited pendulum. The herein developed concept of the parametric pendulum allows reducing the influence of the gravity force thereby significantly improving the device performance at a regular sea state, which could not be achieved in the earlier proposed original point-absorber design. The suggested design of a wave energy converter achieves a dominant rotational motion without any additional mechanisms, like a gearbox, or any active control involvement. Presented numerical results of deterministic and stochastic modeling clearly reflect the advantage of the proposed design. A set of experimental results confirms the numerical findings and validates the new design of a parametric pendulum based wave energy converter. Power harvesting potential of the novel device is also presented.
Numerical simulations of energy transfer in two collisionless interpenetrating plasmas
Directory of Open Access Journals (Sweden)
Davis S.
2013-11-01
Full Text Available Ion stream instabilities are essential for collisionless shock formation as seen in astrophysics. Weakly relativistic shocks are considered as candidates for sources of high energy cosmic rays. Laboratory experiments may provide a better understanding of this phenomenon. High intensity short pulse laser systems are opening possibilities for efficient ion acceleration to high energies. Their collision with a secondary target could be used for collisionless shock formation. In this paper, using particle-in-cell simulations we are studying interaction of a sub-relativistic, laser created proton beam with a secondary gas target. We show that the ion bunch initiates strong electron heating accompanied by the Weibel-like filamentation and ion energy losses. The energy repartition between ions, electrons and magnetic fields are investigated. This yields insight on the processes occurring in the interstellar medium (ISM and gamma-ray burst afterglows.
Numerical simulation and analysis of energy loss in a nanosecond spark gap switch
Lavrinovich, I. V.; Oreshkin, V. I.
2014-11-01
A system of differential equations for the RLC circuit of a capacitor-switch assembly was derived being supplemented with an equation for the spark resistance of the switch in accordance with the Braginsky model. The parameters that affect the solutions of equations for the circuit with parallel or series connection of several capacitor-switch assemblies to a common inductive load were determined. Based on numerical solution of the system of equations, a dependence of the energy ES released in the spark within the first halfperiod on the discharge circuit and switch parameters was found.
Numerical model for two-dimensional hydrodynamics and energy transport. [VECTRA code
Energy Technology Data Exchange (ETDEWEB)
Trent, D.S.
1973-06-01
The theoretical basis and computational procedure of the VECTRA computer program are presented. VECTRA (Vorticity-Energy Code for TRansport Analysis) is designed for applying numerical simulation to a broad range of intake/discharge flows in conjunction with power plant hydrological evaluation. The code computational procedure is based on finite-difference approximation of the vorticity-stream function partial differential equations which govern steady flow momentum transport of two-dimensional, incompressible, viscous fluids in conjunction with the transport of heat and other constituents.
A Numerical Study of Quantization-Based Integrators
Directory of Open Access Journals (Sweden)
Barros Fernando
2014-01-01
Full Text Available Adaptive step size solvers are nowadays considered fundamental to achieve efficient ODE integration. While, traditionally, ODE solvers have been designed based on discrete time machines, new approaches based on discrete event systems have been proposed. Quantization provides an efficient integration technique based on signal threshold crossing, leading to independent and modular solvers communicating through discrete events. These solvers can benefit from the large body of knowledge on discrete event simulation techniques, like parallelization, to obtain efficient numerical integration. In this paper we introduce new solvers based on quantization and adaptive sampling techniques. Preliminary numerical results comparing these solvers are presented.
Development of numerical modelling of analysis program for energy ...
Indian Academy of Sciences (India)
Taiwan. 2Department of Landscape Architecture, National Chin-Yi University of. Technology .... a design tool by engineers for the structural design of buildings, bridges, factories, industrial and public works, and .... cal analysis tool, the dynamic analysis program needs to be developed for energy design in accordance with ...
Numerical study on air turbines with enhanced techniques for OWC wave energy conversion
Cui, Ying; Hyun, Beom-Soo; Kim, Kilwon
2017-10-01
In recent years, the oscillating water column (OWC) wave energy converter, which can capture wave energy from the ocean, has been widely applied all over the world. As the essential part of the OWC system, the impulse and Wells turbines are capable of converting the low pressure pneumatic energy into the mechanical shaft power. As an enhanced technique, the design of endplate or ring attached to the blade tip is investigated numerically in this paper. 3D numerical models based on a CFD-software FLUENT 12.0 are established and validated by the corresponding experimental results from the reports of Setoguchi et al. (2004) and Takao et al. (2001). Then the flow fields and non-dimensional evaluating coefficients are calculated and analyzed under steady conditions. Results show that the efficiency of impulse turbine with ring can reach up to 0.49 when ϕ=1, which is 4% higher than that in the cases for the endplate-type and the original one. And the ring-type Wells turbine with fixed guide vanes shows the best performance with the maximal efficiency of 0.55, which is 22% higher than that of the original one. In addition, the quasi-steady analysis is used to calculate the mean efficiency and output-work of a wave cycle under sinusoidal flow condition. Taking all together, this study provides support for structural optimization of impulse turbine and Wells turbine in the future.
An Energy Preserving Monolithic Eulerian Fluid-Structure Numerical Scheme *
Pironneau, Olivier
2016-01-01
The conservation laws of continuum mechanic written in an Eulerian frame make no difference between fluids and solids except in the expression of the stress tensors, usually with Newton's hypothesis for the fluids and Helmholtz potentials of energy for hyperelastic solids. By taking the velocities as unknown , monolithic methods for fluid structure interactions (FSI) are built. In this article such a formulation is analyzed when the fluid is compressible and the fluid is incompressible. The i...
An Energy stable Monolithic Eulerian Fluid-Structure Numerical Scheme *
Pironneau, Olivier
2017-01-01
The conservation laws of continuum mechanic written in an Eulerian frame make no difference between fluids and solids except in the expression of the stress tensors, usually with Newton's hypothesis for the fluids and Helmholtz potentials of energy for hyperelastic solids. By taking the velocities as unknown , monolithic methods for fluid structure interactions (FSI) are built. In this article such a formulation is analyzed when the fluid is compressible and the fluid is incompressible. The i...
Mutual capture of dipolar molecules at low and very low energies. II. Numerical study.
Auzinsh, M; Dashevskaya, E I; Litvin, I; Nikitin, E E; Troe, J
2011-05-26
The low-energy rate coefficients of capture of two identical dipolar polarizable rigid rotors in their lowest nonresonant (j(1) = 0 and j(2) = 0) and resonant (j(1) = 0, 1 and j(2) = 1, 0) states are calculated accurately within the close-coupling (CC) approach. The convergence of the quantum rate coefficients to their quantum-classical counterparts is studied. A comparison of the present accurate numerical with approximate analytical results (Nikitin, E. E.; Troe, J. J. Phys. Chem. A 2010, 114, 9762) indicates a good performance of the previous approach which was based on the interpolation between s-wave fly wheel quantal and all-wave classical adiabatic channel limits. The results obtained apply as well to the formation of transient molecular species in the encounter of two atoms at very low collision energy interacting via resonance dipole-dipole interaction.
Numerical Modeling of a Shallow Borehole Thermal Energy Storage System
Catolico, N.; Ge, S.; Lu, N.; McCartney, J. S.
2014-12-01
Borehole thermal energy storage (BTES) combined with solar thermal energy harvesting is an economic technological system to garner and store energy as well as an environmentally-sustainable alternative for the heating of buildings. The first community-scale BTES system in North America was installed in 2007 in the Drake Landing Solar Community (DLSC), about 35 miles south of Calgary, Canada. The BTES system involves direct circulation of water heated from solar thermal panels in the summer into a storage tank, after which it is circulate within an array of 144 closed-loop geothermal heat exchangers having a depth of 35 m and a spacing of 2.5 m. In the winter the circulation direction is reversed to supply heat to houses. Data collection over a six year period indicates that this system can supply more than 90% of the winter heating energy needs for 52 houses in the community. One major challenge facing the BTES system technology is the relatively low annual efficiency, i.e., the ratio of energy input and output is in the range of 15% to 40% for the system in Drake Landing. To better understand the working principles of BTES and to improve BTES performance for future applications at larger scales, a three-dimensional transient coupled fluid and heat transfer model is established using TOUGH2. The time-dependent injection temperatures and circulation rate measured over the six years of monitoring are used as model input. The simulations are calibrated using soil temperature data measured at different locations over time. The time-dependent temperature distributions within the borehole region agree well with the measured temperatures for soil with an intrinsic permeability of 10e-19 m2, an apparent thermal conductivity of 2.03 W/m°C, and a volumetric heat capacity of 2.31 MJ/m-3°C. The calibrated model serves as the basis for a sensitivity analysis of soil and operational parameters on BTES system efficiency preformed with TOUGH2. Preliminary results suggest 1) BTES
Zheng, Na; Xu, Hai-Bo
2015-10-01
An empirical numerical model that includes nuclear absorption, multiple Coulomb scattering and energy loss is presented for the calculation of transmission through thick objects in high energy proton radiography. In this numerical model the angular distributions are treated as Gaussians in the laboratory frame. A Monte Carlo program based on the Geant4 toolkit was developed and used for high energy proton radiography experiment simulations and verification of the empirical numerical model. The two models are used to calculate the transmission fraction of carbon and lead step-wedges in proton radiography at 24 GeV/c, and to calculate radial transmission of the French Test Object in proton radiography at 24 GeV/c with different angular cuts. It is shown that the results of the two models agree with each other, and an analysis of the slight differences is given. Supported by NSAF (11176001) and Science and Technology Developing Foundation of China Academy of Engineering Physics (2012A0202006)
Validation of Hydrodynamic Numerical Model of a Pitching Wave Energy Converter
DEFF Research Database (Denmark)
López, Maria del Pilar Heras; Thomas, Sarah; Kramer, Morten Mejlhede
2017-01-01
Validation of numerical model is essential in the development of new technologies. Commercial software and codes available simulating wave energy converters (WECs) have not been proved to work for all the available and upcoming technologies yet. The present paper presents the first stages...... of the validation process of a hydrodynamic numerical model for a pitching wave energy converter. The development of dry tests, wave flume and wave basin experiments are going to be explained, lessons learned shared and results presented....
Janaki R. R. Alavalapati; Pankaj Lal; Andres Susaeta; Robert C. Abt; David N. Wear
2013-01-01
Key FindingsHarvesting woody biomass for use as bioenergy is projected to range from 170 million to 336 million green tons by 2050, an increase of 54 to 113 percent over current levels.Consumption projections for forest biomass-based energy, which are based on Energy Information Administration projections, have a high level of...
Energy Technology Data Exchange (ETDEWEB)
Butt, Zubair; Ahmad, Nasir [Dept. of Mechanical, Mechatronics and Manufacturing Engineering, UET Lahore, Faisalabad Campus, Lahore (Pakistan); Pasha, Riffat Asim; Qayyum, Faisal; Anjum, Zeeshan [Dept. of Mechanical Engineering, University of Engineering and Technology, Taxila (Pakistan); Elahi, Hassan [Northwestern Polytechnical University, Xian (China)
2016-08-15
Energy harvesting is the process of attaining energy from the external sources and transforming it into usable electrical energy. An analytical model of piezoelectric energy harvester has been developed to determine the output voltage across an electrical circuit when it is forced to undergo a base excitation. This model gives an easy approach to design and investigate the behavior of piezoelectric material. Numerical simulations have been carried out to determine the effect of frequency and loading on a Lead zirconate titanate (PZT-5A) piezoelectric material. It has been observed that the output voltage from the harvester increases when loading increases whereas its resonance frequency decreases. The analytical results were found to be in good agreement with the experimental and numerical simulation results.
Numerical study of a water distillation system using solar energy
Energy Technology Data Exchange (ETDEWEB)
Zarzoum, K.; Zhani, K. [Sfax University, (Turkey); Bacha, H. Ben [Prince Sattam Bin Abdulaziz University, Alkharj (Saudi Arabia)
2016-02-15
This paper tackles an optimization approach in order to boost the fresh water production of a new design of a solar still which is located at Sfax engineering national school in Tunisia. This optimization approach is based upon the above mentioned design's improvement by coupling the conventional solar still into at a condenser, solar air and water collector and humidifier. This new concept of a distiller solar still using humidification- dehumidification processes (HD) is exploited for the desalination purpose. As a result of this work, the humidification- dehumidification processes have an essential effect in improving the solar still performance. Performance has been predicted theoretically in terms of water and inner glass cover temperatures, the inlet temperature of air and water of the new concept of distiller on water condensation rate and fresh water production. A general model based on heat and mass transfers in each component of the unit has been developed in steady dynamic regime. The developed model is used, simulating the HD system, to investigate the influence of the meteorological and operating parameters on the system productivity. The obtained set of ordinary differential equations has been converted to a set of algebraic system of equations by the functional approximation method of orthogonal collocation. The developed model is used to simulate the HD system in order to investigate the steady state behavior of each component of the unit and the entire system exposed to a variation of the entrance parameters and meteorological conditions. The obtained results were compared with those of other studies and the comparison gives a good validity of the present results.
Energy Technology Data Exchange (ETDEWEB)
Sunaga, Y. [Central Research Institute of Electric Power Industry, Tokyo (Japan)
1996-08-01
As a part of investigation of transportation planning method for saving energy, a numerical model of commuting traffic flow has been developed using population of cities and geographical data. This is a model of traffic flow based on the analogy between population and quantity of electricity. The working field of electric force is formed around a charge. When the population of cities is replaced by the quantity of charge and the direction of electric force is traced, adequate traffic routes connecting cities with large populations can be obtained. In addition, traffic flow distribution of individual commuting methods was calculated. It was assumed that the traffic flow is decided by attraction force dependent on daytime population of the central city and by influence proportional to the population of cities or towns along the traffic route. Shears of traffics were determined using multiple regression formula based on the traffic service factors in nine urban areas in Japan. The present method was applied to the Tokyo urban area and local core cities, which were compared with the actual number of commuting persons. The both were in good agreement each other. When an urban area is formed around a megalopolis, this model is applicable. 9 refs., 23 figs., 1 tab.
Categorization of Musical Instrument Sounds Based on Numerical Parameters
Lewis, Rory A.; Wieczorkowska, Alicja
In this paper we present methodology of categorization of musical instruments sounds, aiming at the continuing goal of codifying the classiffication of these sounds for automating indexing and retrieval purposes. The proposed categorization is based on numerical parameters. The motivation for this paper is based upon the fallibility of Hornbostel and Sachs generic classiffication scheme, most commonly used for categorization of musical instruments. In eliminating the discrepancies of Hornbostel and Sachs' classiffication of musical sounds we present a procedure that draws categorization from numerical attributes, describing both time domain and spectrum of sound, rather than using classiffication based directly on Hornbostel and Sachs scheme. As a result we propose a categorization system based upon the empirical musical parameters and then incorporating the resultant structure for classiffication rules.
Jacquemot, S.
2017-10-01
This paper provides an overview of the results presented at the 26th IAEA Fusion Energy Conference in the field of inertial confinement fusion for energy, covering its various experimental, numerical/theoretical and technological facets, as well as the different paths towards ignition that are currently followed worldwide.
Unconditionally energy stable numerical schemes for phase-field vesicle membrane model
Guillén-González, F.; Tierra, G.
2018-02-01
Numerical schemes to simulate the deformation of vesicles membranes via minimizing the bending energy have been widely studied in recent times due to its connection with many biological motivated problems. In this work we propose a new unconditionally energy stable numerical scheme for a vesicle membrane model that satisfies exactly the conservation of volume constraint and penalizes the surface area constraint. Moreover, we extend these ideas to present an unconditionally energy stable splitting scheme decoupling the interaction of the vesicle with a surrounding fluid. Finally, the well behavior of the proposed schemes are illustrated through several computational experiments.
Numerical simulation for different densities multi-phase fluids with an energy law preserving method
Li, L.; Jiang, Y. Y.
2017-10-01
In this paper, we present a numerical investigation for simulating fluid-fluid interface of isothermal multi-phase fluids with a phase field model. Unlike the previous work, we use continuous finite element method to compute the governing equations and get a discrete energy law equation with a special designed scheme which is almost the same as the continuous energy law. We deal with the stability in pressure by using a penalty formulation to rewrite the continuity condition. The accuracy of calculation is examined by numerical simulation of coalescence of two kissing bubbles. And the accuracy of the discrete energy law is validated as the error in the energy law of numerical examples falls below discrete level is preserved at each time step.
Numerical Modeling of Fluid Structure Interactions of a Floating Wave Energy Extraction Device
Lee, J.; Kang, S.
2014-12-01
In recent years there has been increased attention towards developing the strategies for harnessing hydrokinetic and wave energy from the ocean. There exists several hydrokinetic energy devices designed to extract energy from the ocean current but few wave energy devices are available. The moored floating cylinder-like structure that has been recently developed in South Korea is one of such devices. We carry out numerical simulation of the three-dimensional interactions of a floating cylinder and incoming waves using the level-set curvilinear immersed boundary method of Kang and Sotiropoulos (2012) to improve the understanding the wave energy extraction mechanisms of that device. The results demonstrate the potential of our numerical model as a powerful engineering tool for predicting complex wave-structure interaction phenomena associated with energy extraction devices.
Idealized numerical modeling of polar mesocyclones dynamics diagnosed by energy budget
Sergeev, Dennis; Stepanenko, Victor
2014-05-01
can be interpreted as the growth rate of the vortex) and energy conversion in the diagnostic equations for kinetic and available potential energy (APE). The energy budget equations are implemented in two forms. The first approach follows the scheme developed by Lorenz (1955) in which KE and APE are broken into a mean component and an eddy component forming a well-known energy cycle. The second method is based on the energy equations that are strictly derived from the governing equations of the numerical mesoscale model used. The latter approach, hence, takes into account all the approximations and numerical features used in the model. Some conclusions based on the comparison of the described methods are presented in the study. A series of high-resolution experiments is carried out using three-dimensional non-hydrostatic limited-area sigma-coordinate numerical model ReMeDy (Research Mesoscale Dynamics), being developed at Lomonosov Moscow State University [3]. An idealized basic state condition is used for all simulations. It is composed of the zonally oriented baroclinic zone over the sea surface partly covered with ice. To realize a baroclinic channel environment zero-gradient boundary conditions at the meridional lateral oundaries are imposed, while the zonal boundary conditions are periodic. The initialization of the mesocyclone is achieved by creating a small axis-symmetric vortex in the center of the model domain. The baroclinicity and stratification of the basic state, as well as the surface parameters, are varied in the typically observed range. References 1. Heinemann G, Øyvind S. 2013. Workshop On Polar Lows. Bull. Amer. Meteor. Soc. 94: ES123-ES126. 2. Yanase W, Niino H. 2006. Dependence of Polar Low Development on Baroclinicity and Physical Processes: An Idealized High-Resolution Experiment, J. Atmos. Sci. 64: 3044-3067. 3. Chechin DG et al. 2013. Idealized dry quasi 2-D mesoscale simulations of cold-air outbreaks over the marginal sea ice zone with fine
Yang, Jing; Zhang, Da-hai; Chen, Ying; Liang, Hui; Tan, Ming; Li, Wei; Ma, Xian-dong
2017-10-01
A novel floating pendulum wave energy converter (WEC) with the ability of tide adaptation is designed and presented in this paper. Aiming to a high efficiency, the buoy's hydrodynamic shape is optimized by enumeration and comparison. Furthermore, in order to keep the buoy's well-designed leading edge always facing the incoming wave straightly, a novel transmission mechanism is then adopted, which is called the tidal adaptation mechanism in this paper. Time domain numerical models of a floating pendulum WEC with or without tide adaptation mechanism are built to compare their performance on various water levels. When comparing these two WECs in terms of their average output based on the linear passive control strategy, the output power of WEC with the tide adaptation mechanism is much steadier with the change of the water level and always larger than that without the tide adaptation mechanism.
Array Optimization for Tidal Energy Extraction in a Tidal Channel – A Numerical Modeling Analysis
Yang, Zhaoqing; Wang, Taiping; Copping, Andrea
2014-01-01
This paper presents an application of a hydrodynamic model to simulate tidal energy extraction in a tidal dominated estuary in the Pacific Northwest coast. A series of numerical experiments were carried out to simulate tidal energy extraction with different turbine array configurations, including location, spacing and array size. Preliminary model results suggest that array optimization for tidal energy extraction in a real-world site is a very complex process that requires consideration of m...
DEFF Research Database (Denmark)
Kepler, Jørgen Asbøl; Hansen, Michael Rygaard
2007-01-01
thickness but significantly smaller than panel length dimensions. Experimental data for the total loss in impactor kinetic energy and momentum and estimated damage energy are described. For a selection of impactor tip shapes, the numerical model is used to evaluate different simplified force histories...... between the impactor and the panel during penetration. The force histories are selected from a primary criterion of conservation of linear momentum in the impactor-panel system, and evaluated according to agreement with the total measured energy balance....
Energy Technology Data Exchange (ETDEWEB)
Kane, L S; Cutler, D E [eds.
1990-09-01
To aid in the processing of bibliographic citations (including cataloging information, subject content indicators and abstracts), data are encoded in a format specific to OSTI. This format allows for computer storage, manipulation, and retrieval using both online and offline systems. Expansion of OSTI's data files to include nonnuclear information is relatively recent, beginning in 1974. OSTI's selection and announcement of technical information now represents a broad spectrum of energy-related fields following current research and development interest in both the domestic and the international arenas. To make the database as comprehensive as possible, current as well as background information is included. As part of its responsibility to build and maintain this database, OSTI accepts data on magnetic tape and floppy diskettes; OSTI's responsibility also includes dissemination of this technical information on magnetic tape as well. Each outgoing tape represents a two-week period of input to the database and may vary from 5000 to 14,000 records per tape. These tapes or diskettes, their format, and data content are described in this document.
Numerical Simulation of Energy Balance in Argon-Helium Mixed Gas Tungsten Arc
Tashiro, Shinichi; Tanaka, Manabu; Nakata, Kazuhiro; Koshiishi, Fusaki; Suzuki, Keiichi; Yamazaki, Kei
High temperature arc plasma produced by employing Gas Tungsten Arc (GTA) is highly controllable, since it is stabilized with a shielding gas. Additionally, GTA requires low cost for equipment investment. Therefore, it is widely utilized as a heat source for material processing such as melting, cutting and welding, or decomposition and detoxification of toxic waste. Energy source properties of GTA strongly depend on the physical properties of the shielding gas. For instance, helium (He) gas or admixture of He gas with argon gas is employed as the shielding gas for conditions requiring high productivity in GTA welding process. Since He has low electrical conductivity especially in low temperature range due to high ionization potential, the current channel in He arc plasma is constricted near the arc axis. Consequently, the enhanced heat input intensity into a base material by the constriction increases weld depth and, thus, leads to the high productivity. However, the effect of the admixture on the heat input characteristics to the base metal is still not clear. In this paper, energy source properties of Ar-He GTA are predicted. The properties of arc plasma and the heat input intensity into a water-cooled copper anode are numerically analyzed.
Wen Wan Xin
2002-01-01
The energy resolution and time resolution of two phi 75 x 100 BGO detectors for high energy gamma ray newly made were measured with sup 1 sup 3 sup 7 Cs and sup 6 sup 0 Co resources. The two characteristic gamma rays of high energy emitted from the thermal neutron capture of germanium in BGO crystal were used for the energy calibration of gamma spectra. The intrinsic photopeak efficiency, single escape probability and double escape probabilities of BGO detectors in photon energy range of 4-30 MeV are numerically calculated with GEANT code. The real count response and count ratio of the uniformly distributed incident photons in energy range of 0-30 MeV are also calculated. The distortion of gamma spectra caused by the photon energy loss extension to lower energy in detection medium is discussed
Energy Data Base: Subject Thesaurus
Energy Technology Data Exchange (ETDEWEB)
Raridon, M.H. (ed.)
1987-09-01
This seventh edition of the subject thesaurus contains the standard vocabulary of indexing terms (descriptors) developed and structured by the technical staff of the Office of Scientific and Technical Information as part of its subject indexing activities for building and maintaining the Energy Data Base (EDB) and other energy information data bases for the Department of Energy (DOE). The purpose of this thesaurus is to enhance the efficiency of information retrieval from these data bases. This structured vocabulary reflects the scope of DOE's research, development, and technological programs and encompasses terminology derived not only from the basic sciences for also from areas of energy resources, conservation, safety, environmental impact, and regulation. There are 21,080 valid descriptors and 5683 forbidden terms in this edition of the Thesaurus. These descriptors are listed alphabetically.
Numerical Forecasting Experiment of the Wave Energy Resource in the China Sea
Directory of Open Access Journals (Sweden)
Chong Wei Zheng
2016-01-01
Full Text Available The short-term forecasting of wave energy is important to provide guidance for the electric power operation and power transmission system and to enhance the efficiency of energy capture and conversion. This study produced a numerical forecasting experiment of the China Sea wave energy using WAVEWATCH-III (WW3, the latest version 4.18 wave model driven by T213 (WW3-T213 and T639 (WW3-T639 wind data separately. Then the WW3-T213 and WW3-T639 were verified and compared to build a short-term wave energy forecasting structure suited for the China Sea. Considering the value of wave power density (WPD, “wave energy rose,” daily and weekly total storage and effective storage of wave energy, this study also designed a series of short-term wave energy forecasting productions. Results show that both the WW3-T213 and WW3-T639 exhibit a good skill on the numerical forecasting of the China Sea WPD, while the result of WW3-T639 is much better. Judging from WPD and daily and weekly total storage and effective storage of wave energy, great wave energy caused by cold airs was found. As there are relatively frequent cold airs in winter, early spring, and later autumn in the China Sea and the surrounding waters, abundant wave energy ensues.
Numerical Model based Reliability Estimation of Selective Laser Melting Process
DEFF Research Database (Denmark)
Mohanty, Sankhya; Hattel, Jesper Henri
2014-01-01
parameters such as laser power, speed, beam profile, etc. Subsequently, uncertainties in the processing parameters are utilized to predict a range for the various outputs, using a Monte Carlo method based uncertainty analysis methodology, and the reliability of the process is established....... various numerical modelling and experimental studies are being carried out to better understand and control the process, there is still a lack of research into establishing the reliability of the process.In this paper, a combined modelling-experimental approach is introduced to establish the reliability...... of the selective laser melting process. A validated 3D finite-volume alternating-direction-implicit numerical technique is used to model the selective laser melting process, and is calibrated against results from single track formation experiments. Correlation coefficients are determined for process input...
Numerical Modelling and Statistical Analysis of Ocean Wave Energy Converters and Wave Climates
Li, Wei
2016-01-01
Ocean wave energy is considered to be one of the important potential renewable energy resources for sustainable development. Various wave energy converter technologies have been proposed to harvest the energy from ocean waves. This thesis is based on the linear generator wave energy converter developed at Uppsala University. The research in this thesis focuses on the foundation optimization and the power absorption optimization of the wave energy converters and on the wave climate modelling a...
Energy-conserving numerical simulations of electron holes in two-species plasmas
Cheng, Yingda; Christlieb, Andrew J.; Zhong, Xinghui
2015-03-01
In this paper, we apply our recently developed energy-conserving discontinuous Galerkin (DG) methods for the two-species Vlasov-Ampère system to simulate the evolution of electron holes (EHs). The EH is an important Bernstein-Greene-Kurskal (BGK) state and is constructed based on the Schamel distribution in our simulation.Even though the knowledge of steady state EHs has advanced significantly, little is known about the full dynamics of EHs that nonlinearly interact with ions in plasmas. In this paper, we simulate the full dynamics of EHs with DG finite element methods, coupled with explicit and implicit time integrators. Our methods are demonstrated to be conservative in the total energy and particle numbers for both species. By varying the mass and temperature ratios, we observe the stationary and moving EHs, as well as the break up of EHs at later times upon initial perturbation of the electron distribution. In addition, we perform a detailed numerical study for the BGK states for the nonlinear evolutions of EH simulations. Our simulation results should help to understand the dynamics of large amplitude EHs that nonlinearly interact with ions in space and laboratory plasmas.
Numerical analysis of energy piles under different boundary conditions and thermal loading cycles
Directory of Open Access Journals (Sweden)
Khosravi Ali
2016-01-01
Full Text Available The thermo- mechanical behavior of energy piles has been studied extensively in recent years. In the present study, a numerical model was adapted to study the effect of various parameters (e.g. heating/cooling temperature, head loading condition and soil stiffness on the thermo-mechanical behavior of an energy pile installed in unsaturated sandstone. The results from the simulations were compared with measurements from a thermal response test on a prototype energy pile installed beneath a 1-story building at the US Air Force Academy (USAFA in Colorado Springs, CO. A good agreement was achieved between the results obtained from the prototype and the numerical models. A parametric evaluation were also carried out which indicated the significance of the stiffness of the unsaturated sandstone and pile’s head loading condition on stress-strain response of the energy pile during heating/cooling cycles.
2D numerical analysis of energy harvesting in oscillating heat pipe using piezoelectric transducers
Vaidya, Sajiree; Myers, Oliver; Thompson, Scott; Shamsaei, Nima; Monroe, John G.
2017-04-01
Energy Harvesting is a powerful process that deals with exploring different possible ways of converting energy dispersed in the environment into more useful form of energy, essentially electrical energy. Piezoelectric materials are known for their ability of transferring mechanical energy into electrical energy or vice versa. Our work takes advantage of piezoelectric material's properties to covert thermal energy into electrical energy in an oscillating heat pipe. Specific interest in an oscillating heat pipe has relevance to energy harvesting for low power generation suitable for remote electronics operation as well as low-power heat reclamation for electronic packaging. The aim of this paper is develop a 2D multi-physics design analysis model that aids in predicting electrical power generation inherent to an oscillating heat pipe. The experimental design shows a piezoelectric patch with fixed configuration, attached inside an oscillating heat pipe and its behavior when subjected to the oscillating fluid pressure was observed. Numerical analysis of the model depicting the similar behavior was done using a multiphysics FEA software. The numerical model consists of a threeway physics interaction that takes into account fluid flow, solid mechanics, and electrical response of the harvester circuit.
Yusoff, A Rashid bin Mohd
2015-01-01
This first book dedicated to the topic provides an up-to-date account of the many opportunities graphene offers for robust, workable energy generation and storage devices. Following a brief overview of the fundamentals of graphene, including the main synthesis techniques, characterization methods and properties, the first part goes on to deal with graphene for energy storage applications, such as lithium-ion batteries, supercapacitors and hydrogen storage. The second part is concerned with graphene-based energy-generation devices, in particular conventional as well as microbial and enzymatic f
The numerical simulation based on CFD of hydraulic turbine pump
Duan, X. H.; Kong, F. Y.; Liu, Y. Y.; Zhao, R. J.; Hu, Q. L.
2016-05-01
As the functions of hydraulic turbine pump including self-adjusting and compensation with each other, it is far-reaching to analyze its internal flow by the numerical simulation based on CFD, mainly including the pressure field and the velocity field in hydraulic turbine and pump.The three-dimensional models of hydraulic turbine pump are made by Pro/Engineer software;the internal flow fields in hydraulic turbine and pump are simulated numerically by CFX ANSYS software. According to the results of the numerical simulation in design condition, the pressure field and the velocity field in hydraulic turbine and pump are analyzed respectively .The findings show that the static pressure decreases systematically and the pressure gradient is obvious in flow area of hydraulic turbine; the static pressure increases gradually in pump. The flow trace is regular in suction chamber and flume without spiral trace. However, there are irregular traces in the turbine runner channels which contrary to that in flow area of impeller. Most of traces in the flow area of draft tube are spiral.
Validation of Hydrodynamic Numerical Model of a Pitching Wave Energy Converter
DEFF Research Database (Denmark)
López, Maria del Pilar Heras; Thomas, Sarah; Kramer, Morten Mejlhede
2017-01-01
Validation of numerical model is essential in the development of new technologies. Commercial software and codes available simulating wave energy converters (WECs) have not been proved to work for all the available and upcoming technologies yet. The present paper presents the first stages of the ...
Numerical modeling of energy-separation in cascaded Leontiev tubes with a central body
Directory of Open Access Journals (Sweden)
Makarov Maksim
2017-01-01
Full Text Available Designs of two- and three-cascaded Leontiev tubes are proposed in the paper. The results of numerical simulation of the energy separation in such tubes are presented. The efficiency parameters are determined in direct flows of helium-xenon coolant with low Prandtl number.
Ganguly, S.; Mohan Kumar, M.S.; Date, Abhijit; Akbarzadeh, Aliakbar
2017-01-01
A three-dimensional (3D) coupled thermo-hydrogeological numerical model for a confined aquifer thermal energy storage (ATES) system underlain and overlain by rock media has been presented in this paper. The ATES system operates in cyclic mode. The model takes into account heat transport processes of
Bio-based lubricants for numerical solution of elastohydrodynamic lubrication
Cupu, Dedi Rosa Putra; Sheriff, Jamaluddin Md; Osman, Kahar
2012-06-01
This paper presents a programming code to provide numerical solution of elastohydrodynamic lubrication problem in line contacts which is modeled through an infinite cylinder on a plane to represent the application of roller bearing. In this simulation, vegetable oils will be used as bio-based lubricants. Temperature is assumed to be constant at 40°C. The results show that the EHL pressure for all vegetable oils was increasing from inlet flow until the center, then decrease a bit and rise to the peak pressure. The shapes of EHL film thickness for all tested vegetable oils are almost flat at contact region.
Numerical simulation of fast photo detectors based on microchannel plates
Ivanov, V.; Barnyakov, A.; Barnyakov, M.; Bobrovnikov, V.; Ovtin, I.
2017-09-01
Description of mathematical models for fast photo detectors based on microchannel plates (MCP) in three-dimensional formulation is given. The models include calculations of photoelectron collection efficiency in the gap photo cathode—MCP, gain factor of secondary electron cascades in the channels, the particle scattering in the gaps between the plates, taking into account the fringe fields and strong external magnetic fields. Comparisons of numerical and experimental data are given. The dependencies of major device parameters vs. of applied voltage, pore size, and magnetic field magnitude have been studied.
Assessment of Soil Liquefaction Potential Based on Numerical Method
DEFF Research Database (Denmark)
Choobasti, A. Janalizadeh; Vahdatirad, Mohammad Javad; Torabi, M.
2012-01-01
, a zone of the corridor of Tabriz urban railway line 2 susceptible to liquefaction was recognized. Then, using numerical analysis and cyclic stress method using QUAKE/W finite element code, soil liquefaction potential in susceptible zone was evaluated based on design earthquake....... simplified method have been developed over the years. Although simplified methods are available in calculating the liquefaction potential of a soil deposit and shear stresses induced at any point in the ground due to earthquake loading, these methods cannot be applied to all earthquakes with the same...
Directory of Open Access Journals (Sweden)
Ahmed Elhanafi
2017-01-01
Full Text Available Offshore oscillating water columns (OWC represent one of the most promising forms of wave energy converters. The hydrodynamic performance of such converters heavily depends on their interactions with ocean waves; therefore, understanding these interactions is essential. In this paper, a fully nonlinear 2D computational fluid dynamics (CFD model based on RANS equations and VOF surface capturing scheme is implemented to carry out wave energy balance analyses for an offshore OWC. The numerical model is well validated against published physical measurements including; chamber differential air pressure, chamber water level oscillation and vertical velocity, overall wave energy extraction efficiency, reflected and transmitted waves, velocity and vorticity fields (PIV measurements. Following the successful validation work, an extensive campaign of numerical tests is performed to quantify the relevance of three design parameters, namely incoming wavelength, wave height and turbine damping to the device hydrodynamic performance and wave energy conversion process. All of the three investigated parameters show important effects on the wave–pneumatic energy conversion chain. In addition, the flow field around the chamber's front wall indicates areas of energy losses by stronger vortices generation than the rear wall.
GPU based numerical simulation of core shooting process
Directory of Open Access Journals (Sweden)
Yi-zhong Zhang
2017-11-01
Full Text Available Core shooting process is the most widely used technique to make sand cores and it plays an important role in the quality of sand cores. Although numerical simulation can hopefully optimize the core shooting process, research on numerical simulation of the core shooting process is very limited. Based on a two-fluid model (TFM and a kinetic-friction constitutive correlation, a program for 3D numerical simulation of the core shooting process has been developed and achieved good agreements with in-situ experiments. To match the needs of engineering applications, a graphics processing unit (GPU has also been used to improve the calculation efficiency. The parallel algorithm based on the Compute Unified Device Architecture (CUDA platform can significantly decrease computing time by multi-threaded GPU. In this work, the program accelerated by CUDA parallelization method was developed and the accuracy of the calculations was ensured by comparing with in-situ experimental results photographed by a high-speed camera. The design and optimization of the parallel algorithm were discussed. The simulation result of a sand core test-piece indicated the improvement of the calculation efficiency by GPU. The developed program has also been validated by in-situ experiments with a transparent core-box, a high-speed camera, and a pressure measuring system. The computing time of the parallel program was reduced by nearly 95% while the simulation result was still quite consistent with experimental data. The GPU parallelization method can successfully solve the problem of low computational efficiency of the 3D sand shooting simulation program, and thus the developed GPU program is appropriate for engineering applications.
Numerical Simulation of Monitoring Corrosion in Reinforced Concrete Based on Ultrasonic Guided Waves
Zheng, Zhupeng; Lei, Ying; Xue, Xin
2014-01-01
Numerical simulation based on finite element method is conducted to predict the location of pitting corrosion in reinforced concrete. Simulation results show that it is feasible to predict corrosion monitoring based on ultrasonic guided wave in reinforced concrete, and wavelet analysis can be used for the extremely weak signal of guided waves due to energy leaking into concrete. The characteristic of time-frequency localization of wavelet transform is adopted in the corrosion monitoring of reinforced concrete. Guided waves can be successfully used to identify corrosion defects in reinforced concrete with the analysis of suitable wavelet-based function and its scale. PMID:25013865
Microscopically Based Nuclear Energy Functionals
Bogner, S. K.
2009-05-01
A major goal of the SciDAC project "Building a Universal Nuclear Energy Density Functional" is to develop next-generation nuclear energy density functionals that give controlled extrapolations away from stability with improved performance across the mass table. One strategy is to identify missing physics in phenomenological Skyrme functionals based on our understanding of the underlying internucleon interactions and microscopic many-body theory. In this contribution, I describe ongoing efforts to use the density matrix expansion of Negele and Vautherin to incorporate missing finite-range effects from the underlying two- and three-nucleon interactions into phenomenological Skyrme functionals.
Numerical Simulation of a Dual-Chamber Oscillating Water Column Wave Energy Converter
Directory of Open Access Journals (Sweden)
Dezhi Ning
2017-09-01
Full Text Available The performance of a dual-chamber Oscillating Water Column (OWC Wave Energy Converter (WEC is considered in the present study. The device has two sub-chambers with a shared orifice. A two-dimensional (2D fully nonlinear numerical wave flume based on the potential-flow theory and the time-domain higher-order boundary element method (HOBEM is applied for the simulation. The incident waves are generated by using the immerged sources and the air-fluid coupling influence is considered with a simplified pneumatic model. In the present study, the variation of the surface elevation and the water column volume in the two sub-chambers are investigated. The effects of the chamber geometry (i.e., the draft and breadth of two chambers on the surface elevation and the air pressure in the chamber are investigated, respectively. It is demonstrated that the surface elevations in the two sub-chambers are strongly dependent on the wave conditions. The larger the wavelength, the more synchronous motion of the two water columns in the two sub-chambers, thus, the lager the variation of the water column volume.
Energy data base: subject thesaurus
Energy Technology Data Exchange (ETDEWEB)
Redford, J.S. (ed.)
1981-10-01
The technical staff of the DOE Technical Information Center, during its subject indexing activities, develops and structures a vocabulary that allows consistent machine storage and retrieval of information necessary to the accomplishment of the DOE mission. This thesaurus incorporates that structured vocabulary. The terminology of this thesaurus is used for the subject control of information announced in DOE Energy Research Abstracts, Energy Abstracts for Policy Analysis, and various update journals and bulletins in specialized areas. This terminology also facilitates subject searching of the DOE Energy Data Base on the DOE/RECON on-line retrieval system and on other commercial retrieval systems. The rapid expansion of the DOE's activities will result in a commitant thesaurus expansion as information relating to new activities is indexed. Only the terms used in the indexing of documents at the Technical Information Center to date are included. (JSR)
Numerical analysis of sliding bearing dynamic characteristics based on CFD
Wang, Kun; Wu, Jinwu; Zhao, Guoyang
2017-10-01
According to the characteristics of the flow field of the sliding bearing, the CFD numerical calculation model of the sliding bearing was established. The CFD method was used to simulate the flow field of the sliding bearing, and the pressure distribution of the sliding bearing flow field was obtained. Based on this, the stiffness and the damping coefficient of the dynamic characteristics were obtained by the dynamic grid technique. The influence of the rotational speed on the dynamic characteristic coefficient was further studied. The results show that the difference between the stiffness coefficient and the damping coefficient is less than 5%, and the accuracy of the model is verified. The absolute value of the oil film stiffness increases non-linearly with the increase of the rotational speed, and the influence of the rotational speed on the damping coefficient is small.
Potential energy curves for diatomic molecules calculated with numerical basis functions
Rantala, Tapio T.; Wästberg, Bo; Rosén, Arne
1986-11-01
A computational scheme for molecules is presented for the evaluation of total enregy properties such as potential energy curves and vibrational frequencies. The calculations are performed within the local density approximation utilizing the LCAO MO scheme with numerical basis functions, and multipole expansion of the molecular charge density is used to obtain the molecular potential. The total energy expression is written in terms of matrix elements already used for solving one-electron equations, and hence any evaluation of explicit integrals over charge density is avoided. The accuracy of the method and the effect of basis set incompleteness are studied for the CO and N 2 molecules and compared with fully numerical (basis-free) results.
Non-Linear Numerical Modeling and Experimental Testing of a Point Absorber Wave Energy Converter
DEFF Research Database (Denmark)
Zurkinden, Andrew Stephen; Ferri, Francesco; Beatty, S.
2014-01-01
A time domain model is applied to a three-dimensional point absorber wave energy converter. The dynamical properties of a semi-submerged hemisphere oscillating around a pivot point where the vertical height of this point is above the mean water level are investigated. The numerical model includes.......e. H/λ≤0.02. For steep waves, H/λ≥0.04 however, the relative velocities between the body and the waves increase thus requiring inclusion of the non-linear hydrostatic restoring moment to effectively predict the dynamics of the wave energy converter. For operation of the device with a passively damping......-linear effect is investigated by a simplified formulation proportional to the quadratic velocity. Results from experiments are shown in order to validate the numerical calculations. All the experimental results are in good agreement with the linear potential theory as long as the waves are sufficiently mild i...
DEFF Research Database (Denmark)
Wang, Weizhi; Wu, Minghao; Palm, Johannes
2018-01-01
The wave loads and the resulting motions of floating wave energy converters are traditionally computed using linear radiation–diffraction methods. Yet for certain cases such as survival conditions, phase control and wave energy converters operating in the resonance region, more complete...... mathematical models such as computational fluid dynamics are preferred and over the last 5 years, computational fluid dynamics has become more frequently used in the wave energy field. However, rigorous estimation of numerical errors, convergence rates and uncertainties associated with computational fluid...... dynamics simulations have largely been overlooked in the wave energy sector. In this article, we apply formal verification and validation techniques to computational fluid dynamics simulations of a passively controlled point absorber. The phase control causes the motion response to be highly nonlinear even...
Directory of Open Access Journals (Sweden)
John V. Ringwood
2013-08-01
Full Text Available Combining offshore wind and wave energy converting apparatuses presents a number of potentially advantageous synergies. To facilitate the development of a proposed floating platform combining these two technologies, proof of concept scale model testing on the wave energy converting component of this platform has been conducted. The wave energy component is based on the well-established concept of the oscillating water column. A numerical model of this component has been developed in the frequency domain, and the work presented here concerns the results of this modelling and testing. The results of both are compared to assess the validity and usefulness of the numerical model.
Energy Technology Data Exchange (ETDEWEB)
Kibar, Ali, E-mail: alikibar@kocaeli.edu.tr [Department of Mechanical and Material Technologies, Kocaeli University, 41285, Arslanbey Campus, Kocaeli (Turkey)
2016-02-15
This study presents the theory of impinging an oblique liquid jet onto a vertical superhydrophobic surface based on both experimental and numerical results. A Brassica oleracea leaf with a 160° apparent contact angle was used for the superhydrophobic surface. Distilled water was sent onto the vertical superhydrophobic surface in the range of 1750–3050 Reynolds number, with an inclination angle of 20°−40°, using a circular glass tube with a 1.75 mm inner diameter. The impinging liquid jet spread onto the surface governed by the inertia of the liquid and then reflected off the superhydrophobic surface due to the surface energy of the spreading liquid. Two different energy approaches, which have time-scale and per-unit length, were performed to determine transformation of the energy. The kinetic energy of the impinging liquid jet was transformed into the surface energy with an increasing interfacial surface area between the liquid and air during spreading. Afterwards, this surface energy of the spreading liquid was transformed into the reflection kinetic energy. (paper)
Energy Technology Data Exchange (ETDEWEB)
Kong, Qiaoling; Ma, Jie; Xia, Dongying [State Key Laboratory of Ocean Engineering, Shanghai Jiaotong University, Shanghai 200030 (China)
2010-04-15
Ocean thermal energy is a type of renewable energy. The phase change process of the thermal glider propelled by ocean thermal energy was numerically and experimentally investigated in this paper. The gliding process was analyzed and optimized while the glider was operating in the ocean thermocline near the equator. The results showed that the time of a cycle decreases by 30% and the gliding depth decreases by 40% after optimization. The gliding process was also analyzed when the PCMs were partly melted with the volumetric expansion rate at 50%, 60%, 70%, 80% and 90% of the total value. With the decreasing of the volumetric expansion rate, the depth and the duration of a cycle decrease significantly, but the output work does not decrease obviously. It is helpful to reduce the manufacturing cost and prolong the duration of the glider. In addition, it can improve the energy harvest efficiency from the ocean thermocline. The vehicle's gliding process can be further investigated in different ocean thermoclines based on the numerical model presented in this paper, which can provide helpful information for optimal design of the thermal glider. (author)
A Floating Ocean Energy Conversion Device and Numerical Study on Buoy Shape and Performance
Directory of Open Access Journals (Sweden)
Ruiyin Song
2016-05-01
Full Text Available Wave and current energy can be harnessed in the East China Sea and South China Sea; however, both areas are subject to high frequencies of typhoon events. To improve the safety of the ocean energy conversion device, a Floating Ocean Energy Conversion Device (FOECD with a single mooring system is proposed, which can be towed to avoid severe ocean conditions or for regular maintenance. In this paper, the structure of the FOECD is introduced, and it includes a catamaran platform, an oscillating buoy part, a current turbine blade, hydraulic energy storage and an electrical generation part. The numerical study models the large catamaran platform as a single, large buoy, while the four floating buoys were modeled simply as small buoys. Theoretical models on wave energy power capture and efficiency were established. To improve the suitability of the buoy for use in the FOECD and its power harvesting capability, a numerical simulation of the four buoy geometries was undertaken. The shape profiles examined in this paper are cylindrical, turbinate (V-shaped and U-shaped cone with cylinder, and combined cylinder-hemisphere buoys. Simulation results reveal that the suitability of a turbinate buoy is the best of the four types. Further simulation models were carried out by adjusting the tip radius of the turbinate buoy. Three performance criteria including suitability, power harvesting capability and energy capture efficiency were analyzed. It reveals that the turbinate buoy has almost the same power harvesting capabilities and energy capture efficiency, while its suitability is far better than that of a cylindrical buoy.
Numerical study on the perception-based network formation model
Jo, Hang-Hyun
2015-01-01
In order to understand the evolution of social networks in terms of perception-based strategic link formation, we numerically study a perception-based network formation model. Here each individual is assumed to have his/her own perception of the actual network, and use it to decide whether to create a link to other individual. An individual with the least perception accuracy can benefit from updating his/her perception using that of the most accurate individual via a new link. This benefit is compared to the cost of linking in decision making. Once a new link is created, it affects the accuracies of other individuals' perceptions, leading to a further evolution of the actual network. The initial actual network and initial perceptions are modeled by Erd\\H{o}s-R\\'enyi random networks but with different linking probabilities. Then the stable link density of the actual network is found to show discontinuous transitions or jumps according to the cost of linking. The effect of initial conditions on the complexity o...
Surface plasmon resonance sensor based on spectral interferometry: numerical analysis.
Zhang, Yunfang; Li, Hui; Duan, Jingyuan; Shi, Ancun; Liu, Yuliang
2013-05-10
In this paper, we introduce a numerical simulation of a phase detecting surface plasmon resonance (SPR) scheme based on spectral interference. Based on the simulation, we propose a method to optimize various aspects of SPR sensors, which enables better performance in both measurement range (MR) and sensitivity. In the simulation, four parameters including the spectrum of the broadband light source, incident angle, Au film thickness, and refractive index of the prism coupler are analyzed. The results show that it is a good solution for better performance to use a warm white broadband (625-800 nm) light source, a divergence angle of the collimated incident light less than 0.02°, and an optimized 48 nm thick Au film when a visible broadband light source is used. If a near-IR light source is used, however, the Au film thickness should be somewhat thinner according the specific spectrum. In addition, a wider MR could be obtained if a prism coupler with higher refractive index is used. With all the parameters appropriately set, the SPR MR could be extended to 0.55 refractive index units while keeping the sensitivity at a level of 10(-8).
Directory of Open Access Journals (Sweden)
Kun Liu
2016-01-01
Full Text Available A novel tuned heave plate energy-harvesting system (THPEH is presented for the motion suppressing and energy harvesting of a semi-submersible platform. This THPEH system is designed based on the principle of a tuned mass damper (TMD and is composed of spring supports, a power take-off system (PTO and four movable heave plates. The permanent magnet linear generators (PMLG are used as the PTO system in this design. A semi-submersible platform operating in the South China Sea is selected as the research subject for investigating the effects of the THPEH system on motion reduction and harvesting energy through numerical simulations. The numerical model of the platform and the THPEH system, which was established based on hydrodynamic analysis, is modified and validated by the results of the flume test of a 1:70 scale model. The effects of the parameters, including the size, the frequency ratio and the damping ratio of the THPEH system, are systematically investigated. The results show that this THPEH system, with proper parameters, could significantly reduce the motions of the semi-submersible platform and generate considerable power under different wave conditions.
Model Reduction Based on a Numerical Length Scale Analysis
Winkler, Niklas; Fuchs, Laszlo
For the time being, the required computational cost to solve the 3D time dependent flow prevents the use of such methods for internal flows at high Reynolds number in complex geometries. In this work we present a method based on a numerical length scale analysis to get a rational reduction of the full 3D governing equations for turbulent pipe flows. The length scale analysis quantifies the terms of the governing equations after changing the coordinate system into a curvilinear coordinate system with one coordinate aligned with the flow path. By retaining the most important terms or neglecting the (significantly) smallest terms, different reductions may be attained. The results for a double bent pipe, used to illustrate the approach, show that the most significant component of the viscous terms is the normal component. The convective terms are all important. The normal component is significant in the bends of the pipe due to centrifugal forces, while the spanwise component is most significant after the second bend due to a swirling motion.
Bertarelli, A; Carra, F; Cerutti, F; Dallocchio, A; Mariani, N; Timmins, M; Peroni, L; Scapin, M
2011-01-01
Beam Intercepting Devices are potentially exposed to severe accidental events triggered by direct impacts of energetic particle beams. State-of-the-art numerical methods are required to simulate the behaviour of affected components. A review of the different dynamic response regimes is presented, along with an indication of the most suited tools to treat each of them. The consequences on LHC tungsten collimators of a number of beam abort scenarios were extensively studied, resorting to a novel category of numerical explicit methods, named Hydrocodes. Full shower simulations were performed providing the energy deposition distribution. Structural dynamics and shock wave propagation analyses were carried out with varying beam parameters, identifying important thresholds for collimator operation, ranging from the onset of permanent damage up to catastrophic failure. Since the main limitation of these tools lies in the limited information available on constitutive material models under extreme conditions, a dedica...
Bertarelli, A; Carra, F; Cerutti, F; Dallocchio, A; Mariani, N; Timmins, M; Peroni, L; Scapin, M
2011-01-01
Beam Intercepting Devices are potentially exposed to severe accidental events triggered by direct impacts of energetic particle beams. State-of-the-art numerical methods are required to simulate the behaviour of affected components. A review of the different dynamic response regimes is presented, along with an indication of the most suited tools to treat each of them. The consequences on LHC tungsten collimators of a number of beam abort scenarios were extensively studied, resorting to a novel category of numerical explicit methods, named Hydrocodes. Full shower simulations were performed providing the energy deposition distribution. Structural dynamics and shock wave propagation analyses were carried out with varying beam parameters, identifying important thresholds for collimator operation, ranging from the onset of permanent damage up to catastrophic failure. Since the main limitation of these tools lies in the limited information available on constitutive material models under extreme conditions, a dedica...
An analytically based numerical method for computing view factors in real urban environments
Lee, Doo-Il; Woo, Ju-Wan; Lee, Sang-Hyun
2018-01-01
A view factor is an important morphological parameter used in parameterizing in-canyon radiative energy exchange process as well as in characterizing local climate over urban environments. For realistic representation of the in-canyon radiative processes, a complete set of view factors at the horizontal and vertical surfaces of urban facets is required. Various analytical and numerical methods have been suggested to determine the view factors for urban environments, but most of the methods provide only sky-view factor at the ground level of a specific location or assume simplified morphology of complex urban environments. In this study, a numerical method that can determine the sky-view factors ( ψ ga and ψ wa ) and wall-view factors ( ψ gw and ψ ww ) at the horizontal and vertical surfaces is presented for application to real urban morphology, which are derived from an analytical formulation of the view factor between two blackbody surfaces of arbitrary geometry. The established numerical method is validated against the analytical sky-view factor estimation for ideal street canyon geometries, showing a consolidate confidence in accuracy with errors of less than 0.2 %. Using a three-dimensional building database, the numerical method is also demonstrated to be applicable in determining the sky-view factors at the horizontal (roofs and roads) and vertical (walls) surfaces in real urban environments. The results suggest that the analytically based numerical method can be used for the radiative process parameterization of urban numerical models as well as for the characterization of local urban climate.
Directory of Open Access Journals (Sweden)
Hadert Nicole
2016-09-01
Full Text Available Metallic implants in magnetic resonance imaging (MRI are a potential safety risk since the energy absorption may increase temperature of the surrounding tissue. The temperature rise is highly dependent on implant size. Numerical examinations can be used to calculate the energy absorption in terms of the specific absorption rate (SAR induced by MRI on orthopaedic implants. This research presents the impact of titanium osteosynthesis spine implants, called spondylodesis, deduced by numerical examinations of energy absorption in simplified spondylodesis models placed in 1.5 T and 3.0 T MRI body coils. The implants are modelled along with a spine model consisting of vertebrae and disci intervertebrales thus extending previous investigations [1], [2]. Increased SAR values are observed at the ends of long implants, while at the center SAR is significantly lower. Sufficiently short implants show increased SAR along the complete length of the implant. A careful data analysis reveals that the particular anatomy, i.e. vertebrae and disci intervertebrales, has a significant effect on SAR. On top of SAR profile due to the implant length, considerable SAR variations at small scale are observed, e.g. SAR values at vertebra are higher than at disc positions.
Verification of Numerical Weather Prediction Model Results for Energy Applications in Latvia
Sīle, Tija; Cepite-Frisfelde, Daiga; Sennikovs, Juris; Bethers, Uldis
2014-05-01
A resolution to increase the production and consumption of renewable energy has been made by EU governments. Most of the renewable energy in Latvia is produced by Hydroelectric Power Plants (HPP), followed by bio-gas, wind power and bio-mass energy production. Wind and HPP power production is sensitive to meteorological conditions. Currently the basis of weather forecasting is Numerical Weather Prediction (NWP) models. There are numerous methodologies concerning the evaluation of quality of NWP results (Wilks 2011) and their application can be conditional on the forecast end user. The goal of this study is to evaluate the performance of Weather Research and Forecast model (Skamarock 2008) implementation over the territory of Latvia, focusing on forecasting of wind speed and quantitative precipitation forecasts. The target spatial resolution is 3 km. Observational data from Latvian Environment, Geology and Meteorology Centre are used. A number of standard verification metrics are calculated. The sensitivity to the model output interpretation (output spatial interpolation versus nearest gridpoint) is investigated. For the precipitation verification the dichotomous verification metrics are used. Sensitivity to different precipitation accumulation intervals is examined. Skamarock, William C. and Klemp, Joseph B. A time-split nonhydrostatic atmospheric model for weather research and forecasting applications. Journal of Computational Physics. 227, 2008, pp. 3465-3485. Wilks, Daniel S. Statistical Methods in the Atmospheric Sciences. Third Edition. Academic Press, 2011.
Note on numerical study of the beam energy spread in NDCX-I
Energy Technology Data Exchange (ETDEWEB)
Vay, J.-L.; Seidl, P.A.; Friedman, A.
2011-01-19
The kinetic energy spread (defined here as the standard deviation of the beam particle energies) sets the ultimate theoretical limit on the longitudinal compression that can be attained on NDCX-I and NDCX-II. Experimental measurements will inevitably include the real influences on the longitudinal phase space of the beam due to injector and accelerator field imperfections1. These induced energy variations may be the real limit to the longitudinal compression in an accelerator. We report on a numerical investigation of the energy spread evolution in NDCX-I; these studies do not include all the real imperfections, but rather are intended to confirm that there are no other intrinsic mechanisms (translaminar effects, transverse-longitudinal anisotropy instability, etc.) for significant broadening of the energy distribution. We have performed Warp simulations that use a realistic Marx voltage waveform which was derived from experimental measurements (averaged over several shots), a fully-featured model of the accelerating and focusing lattice, and new diagnostics for computing the local energy spread (and temperature) that properly account for linear correlations that arise from the discrete binning along each physical dimension (these capabilities reproduce and extend those of the earlier HIF code BPIC). The new diagnostics allow for the calculation of multi-dimensional maps of energy spread and temperature in 2-D axisymmetric or 3-D Cartesian space at selected times. The simulated beam-line was terminated at z = 3 m by a conducting plate, so as to approximately reproduce the experimental conditions at the entrance of the spectrometer that was used for mapping the longitudinal phase space. Snapshots of the beam projection and current, as well as the Marx waveform and history of beam kinetic energy collected at the end plate, are shown in Fig. 1. A two-dimensional axisymmetric map of energy spread from simulations of a typical NDCX-I configuration is shown in Fig. 2 (a
Energy performance of windows based on the net energy gain
DEFF Research Database (Denmark)
Svendsen, Svend; Kragh, Jesper; Laustsen, Jacob Birck
2005-01-01
The paper presents a new method to set up energy performance requirements and energy classes for windows of all dimensions and configurations. The net energy gain of windows is the solar gain minus the heat loss integrated over the heating season. The net energy gain can be calculated for one...... orientation or averaged over different orientations. The averaged value may be used for energy labeling of windows of standard size. Requirements in building codes may also be based on the net energy gain instead of the thermal transmittance of the window. The size and the configuration of the window, i.......e. number of glazing units, have a very large effect on the net energy gain. Therefore the energy labeling or the requirements based on the standard size may not give valid information on the energy performance of windows of non-standard size. The paper presents a method to set up requirements and classes...
Directory of Open Access Journals (Sweden)
Kashani Sina
2014-01-01
Full Text Available The heat transfer enhancement in the latent heat thermal energy storage system through dispersion of nanoparticle is reported. The resulting nanoparticle-enhanced phase change materials exhibit enhanced thermal conductivity in comparison to the base material. Calculation is performed for nanoparticle volume fraction from 0 to 0.08. In this study rectangular and cylindrical containers are modeled numerically and the effect of containers dimensions and nano particle volume fraction are studied. It has been found that the rectangular container requires half of the melting time as for the cylindrical container of the same volume and the same heat transfer area and also, higher nano particle volume fraction result in a larger solid fraction. The increase of the heat release rate of the nanoparticle-enhanced phase change materials shows its great potential for diverse thermal energy storage application.
Numerical investigation on flow behavior and energy separation in a micro-scale vortex tube
Directory of Open Access Journals (Sweden)
Rahbar Nader
2015-01-01
Full Text Available There are a few experimental and numerical studies on the behaviour of micro-scale vortex tubes. The intention of this work is to investigate the energy separation phenomenon in a micro-scale vortex tube by using the computational fluid dynamic. The flow is assumed as steady, turbulent, compressible ideal gas, and the shear-stress transport sst k-w is used for modeling of turbulence phenomenon. The results show that 3-D CFD simulation is more accurate than 2-D axisymmetric one. Moreover, optimum cold-mass ratios to maximize the refrigeration-power and isentropicefficiency are evaluated. The results of static temperature, velocity magnitude and pressure distributions show that the temperature-separation in the micro-scale vortex tube is a function of kinetic-energy variation and air-expansion in the radial direction.
Startsev, Edward; Lee, Wei-li
2005-01-01
In intense charged particle beams with large energy anisotropy, free energy is available to drive transverse electromagnetic Weibel-type instabilities. Such slow-wave transverse electromagnetic instabilities can be described by the so-called Darwin model, which neglects the fast-wave portion of the displacement current. The Weibel instability may also lead to an increase in the longitudinal velocity spread, which would make the focusing of the beam difficult and impose a limit on the minimum spot size achievable in heavy ion fusion experiments. This paper reports the results of recent numerical studies of the Weibel instability using the Beam Eigenmode And Spectra (bEASt) code for space-charge-dominated, low-emittance beams with large tune depression. To study the nonlinear stage of the instability, the Darwin model is being developed and incorporated into the Beam Equilibrium Stability and Transport(BEST) code.
Experimental and Numerical Studies of Solar Chimney for Ventilation in Low Energy Buildings
DEFF Research Database (Denmark)
Zha, Xinyu; Zhang, Jun; Qin, Menghao
2017-01-01
As an effective way to protect environment and save energy in buildings, passive ventilation method has generated intense interest for improving indoor thermal environment in recent years. Among these passive ventilation solutions, design of solar chimney in buildings is a promising approach...... the performance of a full-scale solar chimney in a real building in East-ern China. The measured performance is compared with theoretical calculation and numerical simulation. In a solar chimney of 6.2m length, 2.8m width and 0.35m air gap, the experimental results show that air flow rate of 70.6 m3/h~1887.6 m3/h...... can be achieved during the daytime in the testing day. Comparing measured value with theoretical value, the flow rate is generally lower than the theoretical value. By data analysis, the suggested discharge coefficient Cd of solar energy in real engineering project is 0.51. With the use...
Energy based hybrid turbulence modeling
Haering, Sigfried; Moser, Robert
2015-11-01
Traditional hybrid approaches exhibit deficiencies when used for fluctuating smooth-wall separation and reattachment necessitating ad-hoc delaying functions and model tuning making them no longer useful as a predictive tool. Additionally, complex geometries and flows often require high cell aspect-ratios and large grid gradients as a compromise between resolution and cost. Such transitions and inconsistencies in resolution detrimentally effect the fidelity of the simulation. We present the continued development of a new hybrid RANS/LES modeling approach specifically developed to address these challenges. In general, modeled turbulence is returned to resolved scales by reduced or negative model viscosity until a balance between theoretical and actual modeled turbulent kinetic energy is attained provided the available resolution. Anisotropy in the grid and resolved field are directly integrated into this balance. A viscosity-based correction is proposed to account for resolution inhomogeneities. Both the hybrid framework and resolution gradient corrections are energy conserving through an exchange of resolved and modeled turbulence.
Energy-Based Acoustic Source Localization Methods: A Survey
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Wei Meng
2017-02-01
Full Text Available Energy-based source localization is an important problem in wireless sensor networks (WSNs, which has been studied actively in the literature. Numerous localization algorithms, e.g., maximum likelihood estimation (MLE and nonlinear-least-squares (NLS methods, have been reported. In the literature, there are relevant review papers for localization in WSNs, e.g., for distance-based localization. However, not much work related to energy-based source localization is covered in the existing review papers. Energy-based methods are proposed and specially designed for a WSN due to its limited sensor capabilities. This paper aims to give a comprehensive review of these different algorithms for energy-based single and multiple source localization problems, their merits and demerits and to point out possible future research directions.
Energy-Based Acoustic Source Localization Methods: A Survey.
Meng, Wei; Xiao, Wendong
2017-02-15
Energy-based source localization is an important problem in wireless sensor networks (WSNs), which has been studied actively in the literature. Numerous localization algorithms, e.g., maximum likelihood estimation (MLE) and nonlinear-least-squares (NLS) methods, have been reported. In the literature, there are relevant review papers for localization in WSNs, e.g., for distance-based localization. However, not much work related to energy-based source localization is covered in the existing review papers. Energy-based methods are proposed and specially designed for a WSN due to its limited sensor capabilities. This paper aims to give a comprehensive review of these different algorithms for energy-based single and multiple source localization problems, their merits and demerits and to point out possible future research directions.
Magneto-acoustic wave energy from numerical simulations of an observed sunspot umbra
Felipe, T.; Khomenko, E.; Collados, M.
2011-01-01
We aim at reproducing the height dependence of sunspot wave signatures obtained from spectropolarimetric observations through 3D MHD numerical simulations. A magneto-static sunspot model based on the properties of the observed sunspot is constructed and perturbed at the photosphere introducing the fluctuations measured with the \\SiI\\ $\\lambda$ 10827 \\AA\\ line. The results of the simulations are compared with the oscillations observed simultaneously at different heights from the \\HeI\\ $\\lambda...
Milani, Massimo; Montorsi, Luca; Stefani, Matteo; Saponelli, Roberto; Lizzano, Maurizio
2017-12-01
The paper focuses on the analysis of an industrial ceramic kiln in order to improve the energy efficiency and thus the fuel consumption and the corresponding carbon dioxide emissions. A lumped and distributed parameter model of the entire system is constructed to simulate the performance of the kiln under actual operating conditions. The model is able to predict accurately the temperature distribution along the different modules of the kiln and the operation of the many natural gas burners employed to provide the required thermal power. Furthermore, the temperature of the tiles is also simulated so that the quality of the final product can be addressed by the modelling. Numerical results are validated against experimental measurements carried out on a real ceramic kiln during regular production operations. The developed numerical model demonstrates to be an efficient tool for the investigation of different design solutions for the kiln's components. In addition, a number of control strategies for the system working conditions can be simulated and compared in order to define the best trade off in terms of fuel consumption and product quality. In particular, the paper analyzes the effect of a new burner type characterized by internal heat recovery capability aimed at improving the energy efficiency of the ceramic kiln. The fuel saving and the relating reduction of carbon dioxide emissions resulted in the order of 10% when compared to the standard burner. Copyright © 2017 Elsevier Ltd. All rights reserved.
Numerical and experimental investigation on novel systems for harvesting tidal current energy
Energy Technology Data Exchange (ETDEWEB)
Coiro, D.P. [Naples Univ., Naples (Italy). Dept. of Aerospace Engineering
2008-07-01
Theoretical and experimental tidal current energy investigations currently being conducted at an aerospace engineering department in Italy were presented. The department has set up a test site to harness marine and river current energy in the Messina Strait. A vertical axis hydro turbine developed by the department has been installed at the site. This presentation provided details of unsteady viscous numerical studies conducted to examine flow curvature effects on the turbine's airfoils and rotor design. Numerical studies were also conducted to develop a new generator and optimize the hydrodynamic efficiency of the turbine's rotor. The use of flow increasers to double output power was also examined. The aim of the study was to prove that the vertical axis turbine is capable of reaching the same efficiency levels as horizontal axis turbines. The department is also designing a 300 kW horizontal axis turbine that operates as an underwater ocean kite anchored at the bottom with a winched chain. Details of studies conducted to measure rotational speed, rotor torque, and thrust were presented, as well as details of tests performed at various depths and velocities in order to obtain cavitation numbers for the full-scale turbine. Details of computational fluid dynamics (CFD) studies of the turbine modelled as an actuator disk were also included. tabs., figs.
Franco, Alejandro A; Bessler, Wolfgang G
2015-01-01
This book reviews the use of innovative physical multiscale modeling methods to deeply understand the electrochemical mechanisms and numerically simulate the structure and properties of electrochemical devices for energy storage and conversion.
Operational Energy Base Camp Studies
2011-08-01
criteria for expeditionary military equipment sets. Following the criteria, the paper examines solar panels, wind turbines , and rechargeable batteries...Applications: Solar, Wind, Biomass, Geothermal, Hydrokinetic Energy, Biofuels and Synfuels, Fuel Cells, Microgrids, Smart Meters, and Energy Efficiency
A numerical technique to simulate display pixels based on electrowetting
Roghair, I.; Musterd, M.; van den Ende, Henricus T.M.; Kleijn, C.; Kleijn, C.; Kreutzer, M.T.; Mugele, Friedrich Gunther
2015-01-01
We present a numerical simulation technique to calculate the deformation of interfaces between a conductive and non-conductive fluid as well as the motion of liquid–liquid–solid three-phase contact lines under the influence of externally applied electric fields in electrowetting configuration. The
Numerical Simulation of Solidification Microstructure based on Adaptive Octree Grids
Directory of Open Access Journals (Sweden)
Yin Y.
2016-06-01
Full Text Available The main work of this paper focuses on the simulation of binary alloy solidification using the phase field model and adaptive octree grids. Ni-Cu binary alloy is used as an example in this paper to do research on the numerical simulation of isothermal solidification of binary alloy. Firstly, the WBM model, numerical issues and adaptive octree grids have been explained. Secondary, the numerical simulation results of three dimensional morphology of the equiaxed grain and concentration variations are given, taking the efficiency advantage of the adaptive octree grids. The microsegregation of binary alloy has been analysed emphatically. Then, numerical simulation results of the influence of thermophysical parameters on the growth of the equiaxed grain are also given. At last, a simulation experiment of large scale and long-time has been carried out. It is found that increases of initial temperature and initial concentration will make grain grow along certain directions and adaptive octree grids can effectively be used in simulations of microstructure.
DEFF Research Database (Denmark)
Victor, L.; Troch, P.; Kofoed, Jens Peter
2009-01-01
For overtopping wave energy converters (WECs) a more efficient energy conversion can be achieved when the volumes of water, wave by wave, that enter their reservoir are known and can be predicted. A numerical tool is being developed using a commercial CFD-solver to study and optimize...... nearshore 2Dstructure. First numerical model results are given for a specific test with regular waves, and are compared with the corresponding experimental results in this paper....
Directory of Open Access Journals (Sweden)
Pedro Beirão
2015-09-01
Full Text Available The energy that can be captured from the sea waves and converted into electricity should be seen as a contribution to decrease the excessive dependency and growing demand of fossil fuels. Devices suitable to harness this kind of renewable energy source and convert it into electricity—wave energy converters (WECs—are not yet commercially competitive. There are several types of WECs, with different designs and working principles. One possible classification is their distance to the shoreline and thus their depth. Near-shore devices are one of them since they are typically deployed at intermediate water depth (IWD. The selection of the WEC deployment site should be a balance between several parameters; water depth is one of them. Another way of classifying WECs is grouping them by their geometry, size and orientation. Considering a near-shore WEC belonging to the floating point category, this paper is focused on the numerical study about the differences arising in the power captured from the sea waves when the typical deep water (DW assumption is compared with the more realistic IWD consideration. Actually, the production of electricity will depend, among other issues, on the depth of the deployment site. The development of a dynamic model including specific equations for the usual DW assumption as well as for IWD is also described. Derived equations were used to build a time domain simulator (TDS. Numerical results were obtained by means of simulations performed using the TDS. The objective is to simulate the dynamic behavior of the WEC due to the action of sea waves and to characterize the wave power variations according with the depth of the deployment site.
A numerical model for charge transport and energy conversion of perovskite solar cells.
Zhou, Yecheng; Gray-Weale, Angus
2016-02-14
Based on the continuity equations and Poisson's equation, we developed a numerical model for perovskite solar cells. Due to different working mechanisms, the model for perovskite solar cells differs from that of silicon solar cells and Dye Sensitized Solar Cells. The output voltage and current are calculated differently, and in a manner suited in particular to perovskite organohalides. We report a test of our equations against experiment with good agreement. Using this numerical model, it was found that performances of solar cells increase with charge carrier's lifetimes, mobilities and diffusion lengths. The open circuit voltage (Voc) of a solar cell is dependent on light intensities, and charge carrier lifetimes. Diffusion length and light intensity determine the saturated current (Jsc). Additionally, three possible guidelines for the design and fabrication of perovskite solar cells are suggested by our calculations. Lastly, we argue that concentrator perovskite solar cells are promising.
Energy Technology Data Exchange (ETDEWEB)
Greulich, Johannes, E-mail: johannes.greulich@ise.fraunhofer.de; Höffler, Hannes; Würfel, Uli; Rein, Stefan [Fraunhofer Institute for Solar Energy Systems, Heidenhofstr. 2, D-79110 Freiburg (Germany)
2013-11-28
A method for analyzing the power losses of solar cells is presented, supplying a complete balance of the incident power, the optical, thermodynamic, and electrical power losses and the electrical output power. The involved quantities have the dimension of a power density (units: W/m{sup 2}), which permits their direct comparison. In order to avoid the over-representation of losses arising from the ultraviolet part of the solar spectrum, a method for the analysis of the electrical free energy losses is extended to include optical losses. This extended analysis does not focus on the incident solar power of, e.g., 1000 W/m{sup 2} and does not explicitly include the thermalization losses and losses due to the generation of entropy. Instead, the usable power, i.e., the free energy or electro-chemical potential of the electron-hole pairs is set as reference value, thereby, overcoming the ambiguities of the power balance. Both methods, the power balance and the free energy loss analysis, are carried out exemplarily for a monocrystalline p-type silicon metal wrap through solar cell with passivated emitter and rear (MWT-PERC) based on optical and electrical measurements and numerical modeling. The methods give interesting insights in photovoltaic (PV) energy conversion, provide quantitative analyses of all loss mechanisms, and supply the basis for the systematic technological improvement of the device.
Elkhoury, J. E.; Detwiler, R. L.; Serajian, V.; Bruno, M. S.
2012-12-01
Geothermal energy resources are more widespread than previously thought and have the potential for providing a significant amount of sustainable clean energy worldwide. In particular, hot permeable sedimentary formations provide many advantages over traditional geothermal recovery and enhanced geothermal systems in low permeability crystalline formations. These include: (1) eliminating the need for hydraulic fracturing, (2) significant reduction in risk for induced seismicity, (3) reducing the need for surface wastewater disposal, (4) contributing to decreases in greenhouse gases, and (5) potential use for CO2 sequestration. Advances in horizontal drilling, completion, and production technology from the oil and gas industry can now be applied to unlock these geothermal resources. Here, we present experimental results from a laboratory scale circulation system and numerical simulations aimed at quantifying the heat transfer capacity of sedimentary rocks. Our experiments consist of fluid flow through a saturated and pressurized sedimentary disc of 23-cm diameter and 3.8-cm thickness heated along its circumference at a constant temperature. Injection and production ports are 7.6-cm apart in the center of the disc. We used DI de-aired water and mineral oil as working fluids and explored temperatures from 20 to 150 oC and flow rates from 2 to 30 ml/min. We performed experiments on sandstone samples (Castlegate and Kirby) with different porosity, permeability and thermal conductivity to evaluate the effect of hydraulic and thermal properties on the heat transfer capacity of sediments. The producing fluid temperature followed an exponential form with time scale transients between 15 and 45 min. Steady state outflow temperatures varied between 60% and 95% of the set boundary temperature, higher percentages were observed for lower temperatures and flow rates. We used the flow and heat transport simulator TOUGH2 to develop a numerical model of our laboratory setting. Given
Numerical search of discontinuities in self-consistent potential energy surfaces
Dubray, N.; Regnier, D.
2012-10-01
Potential energy surfaces calculated with self-consistent mean-field methods are a very powerful tool, since their solutions are, in theory, global minima of the non-constrained subspace. However, this minimization leads to an incertitude concerning the saddle points, that can sometimes be no longer saddle points in larger constrained subspaces (fake saddle points), or can be missing on a trajectory (missing saddle points). These phenomena are the consequences of discontinuities of the self-consistent potential energy surfaces (SPESs). These discontinuities may have important consequences, since they can, for example, hide the real height of an energy barrier, and avoid any use of an SPES for further dynamical calculations, barrier penetrability estimations, or trajectory predictions. Discontinuities are not related to the quality of the production of an SPES, since even a perfectly converged SPES with an ideally fine mesh can be discontinuous. In this paper we explain what the discontinuities are, their consequences, and their origins. We then propose a numerical method to detect and identify discontinuities on a given SPES, and finally we discuss what the best ways are to transform a discontinuous SPES into a continuous one.
Numerical Relativity for Space-Based Gravitational Wave Astronomy
Baker, John G.
2011-01-01
In the next decade, gravitational wave instruments in space may provide high-precision measurements of gravitational-wave signals from strong sources, such as black holes. Currently variations on the original Laser Interferometer Space Antenna mission concepts are under study in the hope of reducing costs. Even the observations of a reduced instrument may place strong demands on numerical relativity capabilities. Possible advances in the coming years may fuel a new generation of codes ready to confront these challenges.
Numerical MRI-based breast model for microwave imaging
Rubino, Roselena
2012-01-01
English: Nowadays, the most popular technique for breast cancer detection is the mammography. Due to its drawbacks, other alternative/complementary methods are being researched. In this master thesis, the feasibility of the UWB Magnitude-Combined (MC-UWB) tomographic algorithm is assessed for the breast cancer detection application. This process is done by creating a numerical breast model, calculating its direct problem, applying the algorithm to solve the inverse problem to finally present ...
Energy-efficiency based classification of the manufacturing workstation
Frumuşanu, G.; Afteni, C.; Badea, N.; Epureanu, A.
2017-08-01
EU Directive 92/75/EC established for the first time an energy consumption labelling scheme, further implemented by several other directives. As consequence, nowadays many products (e.g. home appliances, tyres, light bulbs, houses) have an EU Energy Label when offered for sale or rent. Several energy consumption models of manufacturing equipments have been also developed. This paper proposes an energy efficiency - based classification of the manufacturing workstation, aiming to characterize its energetic behaviour. The concept of energy efficiency of the manufacturing workstation is defined. On this base, a classification methodology has been developed. It refers to specific criteria and their evaluation modalities, together to the definition & delimitation of energy efficiency classes. The energy class position is defined after the amount of energy needed by the workstation in the middle point of its operating domain, while its extension is determined by the value of the first coefficient from the Taylor series that approximates the dependence between the energy consume and the chosen parameter of the working regime. The main domain of interest for this classification looks to be the optimization of the manufacturing activities planning and programming. A case-study regarding an actual lathe classification from energy efficiency point of view, based on two different approaches (analytical and numerical) is also included.
Giovannelli, Edoardo; Cioni, Matteo; Procacci, Piero; Cardini, Gianni; Pagliai, Marco; Volkov, Victor; Chelli, Riccardo
2017-12-12
In the companion article (Giovannelli et al., 10.1021/acs.jctc.7b00594), we presented an alchemical approach, based on nonequilibrium molecular dynamics simulations, to compute absolute binding free energies of a generic host-guest system. Two alternative computational routes, called binded-domain and single-point alchemical-path schemes, have been proposed. This study is addressed to furnish numerical validation and illustrative examples of the above-mentioned alchemical schemes. Validation is provided by comparing binding free-energy data relative to two poses of a Zn(II)·anion complex with those recovered from an alternative approach, based on steered molecular dynamics simulations. We illustrate important technical and theoretical aspects for a good practice in applying both alchemical schemes, not only through the calculations on the Zn(II)·anion complex, but also estimating absolute binding free energies of 1:1 complexes of β-cyclodextrin with aromatic compounds (benzene and naphthalene). Comparison with experimental data and previous molecular dynamics simulation studies further confirms the validity of the present nonequilibrium-alchemical methodology.
Directory of Open Access Journals (Sweden)
Yelei Xie
2015-03-01
Full Text Available Dissipative particle dynamics is a particle-based mesoscopic simulation method. Classic dissipative particle dynamics cannot be used to simulate heat transfer in fluids since the total energy of the system is not conserved. In this article, two-dimensional unsteady heat conduction is first investigated using dissipative particle dynamics with energy conservation. The energy conservative dissipative particle dynamics results are compared with the FLUENT simulation data, and it demonstrates that they are in good agreement with each other. Then, forced convection heat transfers in microchannel of the same wall temperature and different wall temperatures are simulated, respectively, by using periodic boundary condition of dimensionless temperature. The results show that the velocity, temperature, and dimensionless temperature distributions are consistent with theoretical results. Finally, we give a qualitative analysis about the applicability of the energy conservative dissipative particle dynamics approach in simulating flow and heat transfer in rough microchannel.
Karami-Lakeh, Hossein; Hosseini-Abardeh, Reza; Kaatuzian, Hassan
2017-05-01
One major problem of solar cells is the decrease in efficiency due to an increase in temperature when operating under constant irradiation of solar energy. The combination of solar cell and a thermoelectric generator is one of the methods proposed to solve this problem. In this paper, the performance of thermo-photovoltaic system is studied experimentally as well as through numerical simulation. In the experimental part, design, manufacture and test of a novel thermo-photovoltaic system assembly are presented. Results of the assembled system showed that with reduction of one degree (Centigrade) in the temperature of solar cell under investigation, and about 0.2 % increase in the efficiency will be obtained in comparison with given efficiency at that specified temperature. The solar cell in a hybrid-assembled system under two cooling conditions (air cooling and water cooling) obtained an efficiency of 8 % and 9.5 %, respectively, while the efficiency of a single cell under the same radiation condition was 6 %. In numerical simulation part, photo-thermoelectric performance of system was analyzed. Two methods for evaluation of thermoelectric performance were used: average properties and finite element method. Results of simulation also demonstrate an increase in solar cell efficiency in the combined system in comparison with that of the single cell configuration.
Springer, H. Keo
2017-06-01
Advanced manufacturing techniques offer control of explosive mesostructures necessary to tailor its shock sensitivity. However, structure-property relationships are not well established for explosives so there is little material design guidance for these techniques. The objective of this numerical study is to demonstrate how TATB-based explosives can be sensitized to shocks using mesostructural features. For this study, we use LX-17 (92.5%wt TATB, 7.5%wt Kel-F 800) as the prototypical TATB-based explosive. We employ features with different geometries and materials. HMX-based explosive features, high shock impedance features, and pores are used to sensitive the LX-17. Simulations are performed in the multi-physics hydrocode, ALE3D. A reactive flow model is used to simulate the shock initiation response of the explosives. Our metric for shock sensitivity in this study is run distance to detonation as a function of applied pressure. These numerical studies are important because they guide the design of novel energetic materials. This work was performed under the auspices of the United States Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-724986.
Fu, S.
2015-12-01
There are many energetic electrons in the radiation belt of Earth. When the geomagnetic activity becomes stronger, the energy flux of energetic electrons will increase to more than ten times in the outer radiation belt, therefore it is very important to study how the energetic electrons generate and the lifetime of energetic electrons for space weather research. The acceleration of electrons in radiation belt is mainly depending on wave-particle interaction: the whistler mode chorus is the main driver for local acceleration mechanism, which could accelerate and loss energetic electrons; the geomagnetic pulsation ULF wave will cause energetic electron inward radial diffusion which will charge the electrons; recently observation results show us that the fast magnetosonic waves may also accelerate energetic electrons. For the reason that we try to study the wave-particle interaction between fast Magnetosonic and energetic electrons based on numerical simulation, in which the most important past is at the storm time the combination of highly warped Earth magnetic field and fast magnetosonic wave field will be applied for the electromagnetic environment of moving test particles. The energy, pitch angle and cross diffusion coefficients will be calculated respectively in this simulation to study how the electrons receive energy from fast magnetosonic wave. The diffusion coefficients within different dipole Earth magnetic field and non-dipole storm magnetic field are compared, while dynamics of electrons at selected initial energys are shown in our study.
Computer-based numerical simulations of adsorption in nanostructures
Khashimova, Diana
2014-08-01
Zeolites are crystalline oxides with uniform, molecular-pore diameters of 3-14Å. Significant developments since 1950 made production of synthetic zeolites with high purity and controlled chemical composition possible. In powder-form, zeolites are major role-players in high-tech, industrial catalysis, adsorption, and ion exchange applications. Understanding properties of thin-film zeolites has been a focus of recent research. The ability to fine-tune desired macroscopic properties by controlled alteration at the molecular level is paramount. The relationships between macroscopic and molecular-level properties are established by experimental research. Because generating macroscopic, experimental data in a controlled laboratory can be prohibitively costly and time-consuming, reliable numerical simulations, which remove such difficulties, are an attractive alternative. Using a Configurational Biased Monte Carlo (CBMC) approach in grand canonical ensemble, numerical models for pure component and multicomponent adsorption processes were developed. Theoretical models such as ideal (IAST) and real adsorbed solution theory (RAST) to predict mixture adsorption in nanopores were used for comparison. Activity coefficients used in RAST calculations were determined from the Wilson, spreading pressure and COSMO-RS models. Investigative testing of the method on known materials, represented by all-silica zeolites such as MFI (channel type) and DDR (cage type), proved successful in replicating experimental data on adsorption of light hydrocarbons - alkanes, such as methane, ethane, propane and butane. Additionally, adsorption of binary and ternary mixtures was simulated. The given numerical approach developed can be a powerful, cost and time saving tool to predict process characteristics for different molecular-structure configurations. The approach used here for simulating adsorption properties of nanopore materials including process characteristics, may have great potential for
Three dimensional numerical prediction of icing related power and energy losses on a wind turbine
Sagol, Ece
Regions of Canada experience harsh winter conditions that may persist for several months. Consequently, wind turbines located in these regions are exposed to ice accretion and its adverse effects, from loss of power to ceasing to function altogether. Since the weather-related annual energy production loss of a turbine may be as high as 16% of the nominal production for Canada, estimating these losses before the construction of a wind farm is essential for investors. A literature survey shows that most icing prediction methods and codes are developed for aircraft, and, as this information is mostly considered corporate intellectual property, it is not accessible to researchers in other domains. Moreover, aircraft icing is quite different from wind turbine icing. Wind turbines are exposed to icing conditions for much longer periods than aircraft, perhaps for several days in a harsh climate, whereas the maximum length of exposure of an aircraft is about 3-4 hours. In addition, wind turbine blades operate at subsonic speeds, at lower Reynolds numbers than aircraft, and their physical characteristics are different. A few icing codes have been developed for wind turbine icing nevertheless. However, they are either in 2D, which does not consider the 3D characteristics of the flow field, or they focus on simulating each rotation in a time-dependent manner, which is not practical for computing long hours of ice accretion. Our objective in this thesis is to develop a 3D numerical methodology to predict rime ice shape and the power loss of a wind turbine as a function of wind farm icing conditions. In addition, we compute the Annual Energy Production of a sample turbine under both clean and icing conditions. The sample turbine we have selected is the NREL Phase VI experimental wind turbine installed on a wind farm in Sweden, the icing events at which have been recorded and published. The proposed method is based on computing and validating the clean performance of the turbine
Suman, Shwetabh; Shah, Haard; Susarla, Vaibhav; Ravi, K.
2017-11-01
According to the statistics it has been seen that everyday nearly 400 people are killed due to road accidents. Due to this it has become an important concern to concentrate on the safety of the passengers which can be done by improving the crashworthiness of the vehicle. During the impact, a large amount of energy is released which if not absorbed, will be transmitted to the passenger compartment. For the safety of the passenger this energy has to be absorbed. Front rail is one of the main energy absorbing components in the vehicle front structure. When it comes to the structure and material of the part or component of the vehicle that is to be designed for crash, it is done based on three parameters: Specific Energy of Absorption, Mass of the front rail and maximum crush force. In this work, we are considering different internal geometries with different materials to increase the energy absorbing capacity of the front rail. Based on the extensive analysis carried aluminium seizes to be the opt material for frontal crash.
Energy based prediction models for building acoustics
DEFF Research Database (Denmark)
Brunskog, Jonas
2012-01-01
In order to reach robust and simplified yet accurate prediction models, energy based principle are commonly used in many fields of acoustics, especially in building acoustics. This includes simple energy flow models, the framework of statistical energy analysis (SEA) as well as more elaborated...... principles as, e.g., wave intensity analysis (WIA). The European standards for building acoustic predictions, the EN 12354 series, are based on energy flow and SEA principles. In the present paper, different energy based prediction models are discussed and critically reviewed. Special attention is placed...
Numerical analysis on RSOD-based phase modulation in OCT
Wang, Ling; Ding, Zhihua; Wang, Kai
2007-05-01
Optical coherence tomography (OCT) is an emerging technology for high-resolution bio-medical imaging. The rapid scanning optical delay line (RSOD) has developed basically for depth scanning and dispersion compensation. If the pivot center of the galvamirror in RSOD is offset, phase modulation can be realized, providing a high carrier frequency required for heterodyne detection. However, the size of galvamirror should be increased, leading to lower response for its oscillation and hence a low scanning rate. In this paper we propose to apply a sinusoidal waveform (resonant scan) instead of a triangle waveform (linear scan) to the galvamirror. Numerical analysis on phase modulation by RSOD and successive envelop demodulation under different driving waveform is conducted. We demonstrate that it is possible to improve OCT frame rate by resonant scan without compromising the signal-to-noise performance if complete and accurate envelope demodulation and appropriate signal processing are adopted.
LED-based Photometric Stereo: Modeling, Calibration and Numerical Solutions
DEFF Research Database (Denmark)
Quéau, Yvain; Durix, Bastien; Wu, Tao
2018-01-01
We conduct a thorough study of photometric stereo under nearby point light source illumination, from modeling to numerical solution, through calibration. In the classical formulation of photometric stereo, the luminous fluxes are assumed to be directional, which is very difficult to achieve...... in practice. Rather, we use light-emitting diodes to illuminate the scene to be reconstructed. Such point light sources are very convenient to use, yet they yield a more complex photometric stereo model which is arduous to solve. We first derive in a physically sound manner this model, and show how...... approach is not established. The second one directly recovers the depth, by formulating photometric stereo as a system of nonlinear partial differential equations (PDEs), which are linearized using image ratios. Although the sequential approach is avoided, initialization matters a lot and convergence...
Energy Technology Data Exchange (ETDEWEB)
Song Junling [College of Postgraduate, the Academy of Equipment Command and Technology, Post Box 3380-86, Huairou Dis. Beijing, 101416 (China); Hong Yanji; Wen Ming, E-mail: songjl@mail.ustc.edu.cn, E-mail: hongyanji@vip.sina.com, E-mail: wujiewm@hotmail.com [Department of Basic theories, the Academy of Equipment Command and Technology, Post Box 3380-86, Huairou Dis. Beijing, 101416 (China)
2011-02-01
A detailed parametric study on the air-breathing laser propulsive performance is carried out for multi-pulses. Based on the finite volume scheme, the detailed evolving process of the inner and outer flow fluids is simulated. The numerical models with different focal positions and laser energies are employed to analyze the parameters effect on the multi-pulses impulse coupling coefficient C{sub m}. Moreover, the laser frequency is discussed and compared with those calculations. The simulation results indicate that the focal position is one of the main factors to influence the multi-pulses C{sub m} at low frequency. For high frequency, it is beneficial to replenish the air in the nozzle when the focal position locates near the nozzle exit. The influence of the laser energy is similar to the single pulse at low frequency, but at high frequency, the partial filling air in the nozzle causes low C{sub m} by high laser energy. The multi-pulses C{sub m} is lower than that of a single pulse. In the same calculative time, the higher the laser frequency, the higher the impulse value, but the lower the C{sub m}.
Starchenko, S. V.
2017-11-01
A hydromagnetic dynamo is only possible at a sufficiently powerful convection. In the Earth's core, it is probably the nonthermal convection very much in excess of its critical level with the molecular transporr coefficients. However, in the case of medium- or large-scale fields, the critical energy level caused by the turbulent tranport coefficients is likely to be slightly below the actual level. This probably explains both the 22-year success of this type of simplified geodynamo models and the energy scaling laws for hydromagnetic fields, which generalize these models. Also the review of energy-dependent analytical and observational estimates of vortex fields, hydromagnetic scale sizes, and velocities in the core is presented. These typical parameters are partly in a new way linked to the observed and more ancient magnetic variations. New, albeit, simplified and self-evident, substantiation is given to the paleomagnetic hypothesis about the predominance of the axial dipole under a certain time averaging. In (Pozzo et al., 2012) and more recent works, it is shown that the adiabatic heat flow and electrical conductivity in the Earth's core are severalfold higher than the generally accepted estimates. Here, the dynamo supporting Braginsky's convection (Braginsky, 1963) (under the crystallization of the heavy fraction of a liquid onto the solid core) started less than 1 Ga ago, whereas the more ancient geodynamo was supported by the compositional convection of another type. The known mechanisms implementing this convection, which differ by the scenarios of magnetic evolution, are reviewed. This may help identify the sought mechanism through the most ancient paleomagnetic estimates of the field's intensity and through the numerical models. The probable mechanisms of generation and their absence for the primordial and recent magnetic field of the studied terrestrial planets are discussed.
Numerical estimation of deformation energy of selected bulk oilseeds in compression loading
Demirel, C.; Kabutey, A.; Herak, D.; Gurdil, G. A. K.
2017-09-01
This paper aimed at the determination of the deformation energy of some bulk oilseeds or kernels namely oil palm, sunflower, rape and flax in linear pressing applying the trapezoidal rule which is characterized by the area under the force and deformation curve.The bulk samples were measured at the initial pressing height of 60 mm with the vessel diameter of 60 mm where they were compressed under the universal compression machine at a maximum force of 200 kN and speed of 5 mm/min.Based on the compression test, the optimal deformation energy for recovering the oil was observed at a force of 163 kN where there was no seed/kernel cake ejection in comparison to the initial maximum force used particularly for rape and flax bulk oilseeds.This information is needed for analyzing the energy efficiency of the non-linear compression process involving a mechanical screw press or expeller.
A numerical study of latent thermal energy storage in a phase change material/carbon panel
Energy Technology Data Exchange (ETDEWEB)
Mekaddem, Najoua, E-mail: mekaddem.najoua@gmail.com; Ali, Samia Ben, E-mail: samia.benali@enig.rnu.tn; Hannachi, Ahmed, E-mail: ahmed.hannachi@enig.rnu.tn [Research Laboratory of Process Engineering and Industrial Systems, National Engineering School of Gabes (Tunisia); Mazioud, Atef, E-mail: mazioud@u-pec.fr [IUT Senart, Department of Industrial Engineering and Maintenance, University Paris-Est (France)
2016-07-25
To reduce the energetic dependence of building, it has become necessary to explore and develop new materials promoting energy conservation. Because of their high storage capacity, phase change materials (PCMs) are efficient to store thermal energy. In this paper, a 3D model was studied for simulation of energy storing cycles to predict the performances of PCM loaded panels. Carbon was used as supporting material for the PCM. The simulation was based on the enthalpy method using Ansys Fluent software. The panel was exposed to a daily heat flow including the effects of convection and radiation. The results show that the temperature decreased of approximately 2.5°C with a time shift about 2 hours. The steady state was reached after four cycles. Thus, after four cycles the PCM showed its effects on the temperature conditioning.
DEFF Research Database (Denmark)
Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen
2011-01-01
introduced in this paper is much easier to use and is computational faster. This method is derived based on the “apparent energy.” Calculation of the nonlinear flux linkage from this energy avoids numerical differentiation, which is sensitive to numerical errors but is required in the traditional energy...
Ullah, Asmat; Chen, Wen; Khan, Mushtaq Ahmad
2017-07-01
This paper introduces a fractional order total variation (FOTV) based model with three different weights in the fractional order derivative definition for multiplicative noise removal purpose. The fractional-order Euler Lagrange equation which is a highly non-linear partial differential equation (PDE) is obtained by the minimization of the energy functional for image restoration. Two numerical schemes namely an iterative scheme based on the dual theory and majorization- minimization algorithm (MMA) are used. To improve the restoration results, we opt for an adaptive parameter selection procedure for the proposed model by applying the trial and error method. We report numerical simulations which show the validity and state of the art performance of the fractional-order model in visual improvement as well as an increase in the peak signal to noise ratio comparing to corresponding methods. Numerical experiments also demonstrate that MMAbased methodology is slightly better than that of an iterative scheme.
Energy conserving numerical methods for the computation of complex vortical flows
Allaneau, Yves
One of the original goals of this thesis was to develop numerical tools to help with the design of micro air vehicles. Micro Air Vehicles (MAVs) are small flying devices of only a few inches in wing span. Some people consider that as their size becomes smaller and smaller, it would be increasingly more difficult to keep all the classical control surfaces such as the rudders, the ailerons and the usual propellers. Over the years, scientists took inspiration from nature. Birds, by flapping and deforming their wings, are capable of accurate attitude control and are able to generate propulsion. However, the biomimicry design has its own limitations and it is difficult to place a hummingbird in a wind tunnel to study precisely the motion of its wings. Our approach was to use numerical methods to tackle this challenging problem. In order to precisely evaluate the lift and drag generated by the wings, one needs to be able to capture with high fidelity the extremely complex vortical flow produced in the wake. This requires a numerical method that is stable yet not too dissipative, so that the vortices do not get diffused in an unphysical way. We solved this problem by developing a new Discontinuous Galerkin scheme that, in addition to conserving mass, momentum and total energy locally, also preserves kinetic energy globally. This property greatly improves the stability of the simulations, especially in the special case p=0 when the approximation polynomials are taken to be piecewise constant (we recover a finite volume scheme). In addition to needing an adequate numerical scheme, a high fidelity solution requires many degrees of freedom in the computations to represent the flow field. The size of the smallest eddies in the flow is given by the Kolmogoroff scale. Capturing these eddies requires a mesh counting in the order of Re³ cells, where Re is the Reynolds number of the flow. We show that under-resolving the system, to a certain extent, is acceptable. However our
Models and numerical methods for time- and energy-dependent particle transport
Energy Technology Data Exchange (ETDEWEB)
Olbrant, Edgar
2012-04-13
Particles passing through a medium can be described by the Boltzmann transport equation. Therein, all physical interactions of particles with matter are given by cross sections. We compare different analytical models of cross sections for photons, electrons and protons to state-of-the-art databases. The large dimensionality of the transport equation and its integro-differential form make it analytically difficult and computationally costly to solve. In this work, we focus on the following approximative models to the linear Boltzmann equation: (i) the time-dependent simplified P{sub N} (SP{sub N}) equations, (ii) the M{sub 1} model derived from entropy-based closures and (iii) a new perturbed M{sub 1} model derived from a perturbative entropy closure. In particular, an asymptotic analysis for SP{sub N} equations is presented and confirmed by numerical computations in 2D. Moreover, we design an explicit Runge-Kutta discontinuous Galerkin (RKDG) method to the M{sub 1} model of radiative transfer in slab geometry and construct a scheme ensuring the realizability of the moment variables. Among other things, M{sub 1} numerical results are compared with an analytical solution in a Riemann problem and the Marshak wave problem is considered. Additionally, we rigorously derive a new hierarchy of kinetic moment models in the context of grey photon transport in one spatial dimension. For the perturbed M{sub 1} model, we present numerical results known as the two beam instability or the analytical benchmark due to Su and Olson and compare them to the standard M{sub 1} as well as transport solutions.
Energy Technology Data Exchange (ETDEWEB)
Pelanti, Marica, E-mail: marica.pelanti@ensta-paristech.fr [Department of Mechanical Engineering, École Nationale Supérieure de Techniques Avancées – ENSTA ParisTech, 828, Boulevard des Maréchaux, 91762 Palaiseau Cedex (France); Shyue, Keh-Ming, E-mail: shyue@ntu.edu.tw [Department of Mathematics, National Taiwan University, Taipei 106, Taiwan (China)
2014-02-15
We model liquid–gas flows with cavitation by a variant of the six-equation single-velocity two-phase model with stiff mechanical relaxation of Saurel–Petitpas–Berry (Saurel et al., 2009) [9]. In our approach we employ phasic total energy equations instead of the phasic internal energy equations of the classical six-equation system. This alternative formulation allows us to easily design a simple numerical method that ensures consistency with mixture total energy conservation at the discrete level and agreement of the relaxed pressure at equilibrium with the correct mixture equation of state. Temperature and Gibbs free energy exchange terms are included in the equations as relaxation terms to model heat and mass transfer and hence liquid–vapor transition. The algorithm uses a high-resolution wave propagation method for the numerical approximation of the homogeneous hyperbolic portion of the model. In two dimensions a fully-discretized scheme based on a hybrid HLLC/Roe Riemann solver is employed. Thermo-chemical terms are handled numerically via a stiff relaxation solver that forces thermodynamic equilibrium at liquid–vapor interfaces under metastable conditions. We present numerical results of sample tests in one and two space dimensions that show the ability of the proposed model to describe cavitation mechanisms and evaporation wave dynamics.
Energy information data base: subject thesaurus
Energy Technology Data Exchange (ETDEWEB)
1979-10-01
The technical staff of the DOE Technical Information Center, during its subject indexing activities, develops and structures a vocabulary that allows consistent machine storage and retrieval of information necessary to the accomplishment of the DOE mission. This thesaurus incorporates that structured vocabulary. The terminology of this thesaurus is used for the subject control of information announced in DOE Energy Research Abstracts, Energy Abstracts for Policy Analysis, Solar Energy Update, Geothermal Energy Update, Fossil Energy Update, Fusion Energy Update, and Energy Conservation Update. This terminology also facilitates subject searching of the DOE energy information data base, a research in progress data base, a general and practical energy information data base, power reactor docket information data base, nuclear science abstracts data base, and the federal energy information data base on the DOE on-line retrieval system, RECON. The rapid expansion of the DOE's activities will result in a concomitant thesaurus expansion as information relating to new activities is indexed. Only the terms used in the indexing of documents at the Technical Information Center to date are included. (RWR)
LCA of biomass-based energy systems
DEFF Research Database (Denmark)
Tonini, Davide; Astrup, Thomas Fruergaard
2012-01-01
Decrease of fossil fuel consumption in the energy sector is an important step towards more sustainable energy production. Environmental impacts related to potential future energy systems in Denmark with high shares of wind and biomass energy were evaluated using life-cycle assessment (LCA). Based...... on the reference year 2008, energy scenarios for 2030 and 2050 were assessed. For 2050 three alternatives for supply of transport fuels were considered: (1) fossil fuels, (2) rapeseed based biodiesel, and (3) Fischer–Tropsch based biodiesel. Overall, the results showed that greenhouse gas emissions per PJ energy...... on the amounts and types of energy crops introduced. Use of fossil diesel in the transport sector appeared to be environmentally preferable over biodiesel for acidification, aquatic eutrophication and land occupation. For global warming, biodiesel production via Fischer–Tropsch was comparable with fossil diesel....
Directory of Open Access Journals (Sweden)
Kasni Sumeru
2013-07-01
Full Text Available The present study describes a numerical approach for determining both the motive nozzle and constant-area diameters of an ejector as an expansion device, based on the cooling capacity of a split-type air-conditioner using R290 as refrigerant. Previous studies have shown that replacement of HCFC R22 with HC290 (propane in the air conditioner can improve the coefficient of performance (COP. The purpose of replacing the capillary tube with an ejector as an expansion device in a split-type air conditioner using HC290 is to further improve the COP. In developing the model, conservation laws of mass, momentum and energy equations were applied to each part of the ejector. The numerical results show that the motive nozzle diameter remains constant (1.03 mm under varying condenser temperatures, whereas the diameter of the constant-area decreases as the condenser temperature increases. It was also found that improvement of the COP can reach 32.90% at a condenser temperature of 55 °C. From the results mentioned above, it can be concluded that the use of an ejector can further improve the COP of a split-type air conditioner using HC290 as working fluid.
Numerical Investigation of Tunable Plasmonic Tweezers based on Graphene Stripes.
Samadi, Mohsen; Darbari, Sara; Moravvej-Farshi, Mohammad Kazem
2017-11-06
We are proposing tunable plasmonic tweezers, consisting two parallel graphene stripes, which can be utilized to effectively trap and sort nanoparticles. We show that by electrostatically tuning the chemical potential of a graphene stripe by about 100 meV (equivalent to ΔV G ≈ 4.4 V), the plasmonic force can be switched efficiently, without a need to switch the laser intensity. This enables high speed and low power switching with a large number of switching cycles. By applying two independent and appropriate gate bias voltages to the stripes, the direction of the plasmonic force can be reversed, which leads to separation of nanoparticles that satisfy the trapping conditions. Numerical simulations show that the potential depths obtained for polystyrene nanoparticles of refractive index n = 1.5717 and radii r ≥ 50 nm is deeper than -10 k B T , confirming the ability of the proposed system to effectively separate such nanoparticles. This capability holds for smaller nanoparticles with larger refractive indices. Finally, performing thermal simulations, we have demonstrated that the heat induced by the illumination increases the fluid temperature by at most 9 °C, having negligible effect on the trapping mechanism. The proposed system opens up new possibilities in developing tunable on-chip manipulation devices, suitable for biological applications.
Numerical investigation of smart base isolation system employing MR elastomer
Energy Technology Data Exchange (ETDEWEB)
Usman, M; Sung, S H; Jang, D D; Jung, H J [Department of Civil and Environmental Engineering, KAIST, 305-701, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Koo, J H [Department of Mechanical and Manufacturing Engineering, Miami University, Oxford, Ohio 45056 (United States)], E-mail: hjung@kaist.ac.kr
2009-02-01
This paper evaluates the dynamic performance of a newly proposed smart base isolation system employing Magneto-Rheological Elastomers (MREs). MREs belong to a class of smart materials whose elastic modulus or stiffness can be adjusted by varying the magnitude of the magnetic field. The base isolation systems are considered as one of the most effective devices for vibration reduction of civil engineering structures in the event of earthquakes. The proposed base isolation system strives to enhance the performance of the conventional base-isolation system by using controllable MREs. To validate the effectiveness of the MRE-based isolation system, an extensive simulation study has been performed using a five degree-of-freedom structure under several historical earthquake excitations. The results show that the proposed system outperformed the conventional system in reducing the responses of the structure in all the seismic excitations considered in the study.
Shefer, O. V.; Shefer, V. A.; Sinyukova, E. A.
2014-12-01
Studies of the role of atmospheric formations and cosmic dust clouds in the transmission of radiation is one of the most uncertain and difficult problems in astrophysics and climatology. One of the main tasks of practical astrophysics is the interpretation of the results of observations of space objects. There is a necessity of describing the propagation of electromagnetic waves in the environment. In this paper, applying the numerical methods, we study the optical characteristics of polydisperse media consisting of randomly oriented and preferentially oriented crystals, taking into account the distribution function of particle sizes. Particles of spherical shape and ensembles preferentially oriented plate crystals are considered as models. Mie theory and method of physical optics are used to calculate the scattering characteristics. Numerical study of the effects of extinction, scattering and absorption on the single scattering albedo of radiation allowed us to establish the basic patterns of the passage of radiant energy through a translucent medium. At the visible range of wavelengths, both for small and large particles, the single scattering albedo is almost equal to 1. The spectral course of this optical performance is mainly determined by the refractive index of the particles. Features of wave dependence of single scattering albedo are associated with microphysical parameters of the environment, which are more pronounced when the attenuation of the radiation is determined mainly by the scattering. Higher values of the absorption index and optical thickness of the crystal reduce the value of the single scattering albedo, smoothing the features of its spectral course. Values of the absorption index of substance, as value of the order of 0.1, do not lead to a decrease of the single scattering albedo as it is less than 0.5. This allows us to conclude that we should not neglect the microphysical characteristics of the crystals even by strong absorption of radiant
Numerical study on Wells turbine with penetrating blade tip treatments for wave energy conversion
Directory of Open Access Journals (Sweden)
Ying Cui
2016-09-01
Full Text Available In order to optimize the performance of a Wells turbine with fixed guide vanes, the designs of an end plate and a ring on the tip of the turbine rotor are proposed as penetrating blade tip treatments. In this study, numerical investigations are made using computational fluid dynamics (CFD-based ANSYS Fluent software, and validated by corresponding experimental data. The flow fields are analyzed and non-dimensional coefficients CA, CT and η are calculated under steady-state conditions. Numerical results show that the stalling phenomenon on a ring-type Wells turbine occurs at a flow coefficient of ϕ = 0.36, and its peak efficiency can reach 0.54, which is 16% higher than that of an unmodified turbine and 9% higher than in the case of an endplate-type turbine. In addition, quasi-steady analysis is used to calculate the mean efficiency and output work of a wave cycle under sinusoidal flow conditions. As a result, it has been found that the ring-type turbine is superior to other types of Wells turbines.
Teaching numerical methods with IPython notebooks and inquiry-based learning
Ketcheson, David I.
2014-01-01
A course in numerical methods should teach both the mathematical theory of numerical analysis and the craft of implementing numerical algorithms. The IPython notebook provides a single medium in which mathematics, explanations, executable code, and visualizations can be combined, and with which the student can interact in order to learn both the theory and the craft of numerical methods. The use of notebooks also lends itself naturally to inquiry-based learning methods. I discuss the motivation and practice of teaching a course based on the use of IPython notebooks and inquiry-based learning, including some specific practical aspects. The discussion is based on my experience teaching a Masters-level course in numerical analysis at King Abdullah University of Science and Technology (KAUST), but is intended to be useful for those who teach at other levels or in industry.
Numerical Simulation of Recycled Concrete Using Convex Aggregate Model and Base Force Element Method
Directory of Open Access Journals (Sweden)
Yijiang Peng
2016-01-01
Full Text Available By using the Base Force Element Method (BFEM on potential energy principle, a new numerical concrete model, random convex aggregate model, is presented in this paper to simulate the experiment under uniaxial compression for recycled aggregate concrete (RAC which can also be referred to as recycled concrete. This model is considered as a heterogeneous composite which is composed of five mediums, including natural coarse aggregate, old mortar, new mortar, new interfacial transition zone (ITZ, and old ITZ. In order to simulate the damage processes of RAC, a curve damage model was adopted as the damage constitutive model and the strength theory of maximum tensile strain was used as the failure criterion in the BFEM on mesomechanics. The numerical results obtained in this paper which contained the uniaxial compressive strengths, size effects on strength, and damage processes of RAC are in agreement with experimental observations. The research works show that the random convex aggregate model and the BFEM with the curve damage model can be used for simulating the relationship between microstructure and mechanical properties of RAC.
Bedarev, I. A.; Vankova, O. S.; Goldfeld, M. A.; Temerbekov, V. M.; Fedorova, N. N.; Fedorov, A. V.
2017-10-01
The results of numerical studies of the interaction of a detonation wave and an electron beam with supersonic reacting flows in channel of various configurations like channel with backward-facing step, symmetrical channel with abrupt expansion and channel with a cavity are presented. A mathematical technology has been created to implement such interaction based on the ANSYS Fluent software. The flow parameters at the outlet of the channel are compared for different channel configurations and ignition initiation ways. The possibility is shown to intensify the ignition in a supersonic flow by electron beams and pulsating detonation. The possibility is identified to use a cavity for stabilizing the combustion in a supersonic combustion chamber when exposed to a detonation wave.
Numerical study of the air-flow in an oscillating water column wave energy converter
Energy Technology Data Exchange (ETDEWEB)
Paixao Conde, J.M. [Department of Mechanical and Industrial Engineering, Faculty of Sciences and Technology, New University of Lisbon, Monte de Caparica, 2829-516 Caparica (Portugal); IDMEC, Instituto Superior Tecnico, Technical University of Lisbon, 1049-001 Lisboa (Portugal); Gato, L.M.C. [IDMEC, Instituto Superior Tecnico, Technical University of Lisbon, 1049-001 Lisboa (Portugal)
2008-12-15
The paper presents a numerical study of the air-flow in a typical pneumatic chamber geometry of an oscillating water column (OWC)-type wave energy converter (WEC), equipped with two vertical-axis air turbines, asymmetrically placed on the top of the chamber. Outwards and inwards, steady and periodic, air-flow calculations were performed to investigate the flow distribution at the turbines' inlet sections, as well as the properties of the air-jet impinging on the water free-surface. The original design of the OWC chamber is likely to be harmful for the operation of the turbines due to the possible air-jet-produced water-spray at the water free-surface subsequently ingested by the turbine. A geometry modification of the air chamber, using a horizontal baffle-plate to deflect the air from the turbines, is proposed and proved to be very effective in reducing the risk of water-spray production from the inwards flow. The flow distribution at the turbines' inlet sections for the outwards flow was found to be fairly uniform for the geometries considered, providing good inlet flow conditions for the turbines. Steady flow was found to be an acceptable model to study the air-flow inside the pneumatic chamber of an OWC-WEC. (author)
Human motion energy harvesting: numerical analysis of electromagnetic swing-excited structures
Ylli, K.; Hoffmann, D.; Willmann, A.; Folkmer, B.; Manoli, Y.
2016-09-01
Energy harvesting from human motion has constantly attracted scientific interest over recent years. A location where a harvesting device can easily and unobtrusively be integrated is the shoe sole, which also protects the device from exterior influences. In this work a numerical system model is developed, which can be used to simulate different inductive harvester geometries and predict their power output. Real world acceleration data is used as a model input. The model is implemented in Matlab/Simulink and subdivided into a mechanical and an electromagnetic model. The key features including the motion model and the calculation of the electromagnetic coupling coefficient are explained in detail and the model is briefly evaluated experimentally. A total of six inductive architectures, i.e. different cylindrical and rectangular magnet-coil arrangements, are then investigated in detail. The geometrical parameters are optimized for each architecture to find the best geometry within the size of 71 mm × 37.5 mm × 12.5 mm, which can be integrated into the sole. With the best overall design an average power output of 42.7 mW is simulated across an ohmic load of 41 Ohms. In addition to the respective best designs, the (dis-)advantages of each architecture are explained.
Cellulose-Based Nanomaterials for Energy Applications.
Wang, Xudong; Yao, Chunhua; Wang, Fei; Li, Zhaodong
2017-11-01
Cellulose is the most abundant natural polymer on earth, providing a sustainable green resource that is renewable, degradable, biocompatible, and cost effective. Recently, nanocellulose-based mesoporous structures, flexible thin films, fibers, and networks are increasingly developed and used in photovoltaic devices, energy storage systems, mechanical energy harvesters, and catalysts components, showing tremendous materials science value and application potential in many energy-related fields. In this Review, the most recent advancements of processing, integration, and application of cellulose nanomaterials in the areas of solar energy harvesting, energy storage, and mechanical energy harvesting are reviewed. For solar energy harvesting, promising applications of cellulose-based nanostructures for both solar cells and photoelectrochemical electrodes development are reviewed, and their morphology-related merits are discussed. For energy storage, the discussion is primarily focused on the applications of cellulose-based nanomaterials in lithium-ion batteries, including electrodes (e.g., active materials, binders, and structural support), electrolytes, and separators. Applications of cellulose nanomaterials in supercapacitors are also reviewed briefly. For mechanical energy harvesting, the most recent technology evolution in cellulose-based triboelectric nanogenerators is reviewed, from fundamental property tuning to practical implementations. At last, the future research potential and opportunities of cellulose nanomaterials as a new energy material are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Directory of Open Access Journals (Sweden)
Ikuo Yamamoto
2017-10-01
Full Text Available The generation of clean renewable energy is becoming increasingly critical, as pollution and global warming threaten the environment in which we live. While there are many different kinds of natural energy that can be harnessed, marine tidal energy offers reliability and predictability. However, harnessing energy from tidal flows is inherently difficult, due to the harsh environment. Current mechanisms used to harness tidal flows center around propeller-based solutions but are particularly prone to failure due to marine fouling from such as encrustations and seaweed entanglement and the corrosion that naturally occurs in sea water. In order to efficiently harness tidal flow energy in a cost-efficient manner, development of a mechanism that is inherently resistant to these harsh conditions is required. One such mechanism is a simple oscillatory-type mechanism based on robotic fish tail fin technology. This uses the physical phenomenon of vortex-induced oscillation, in which water currents flowing around an object induce transverse motion. We consider two specific types of oscillators, firstly a wing-type oscillator, in which the optimal elastic modulus is being sort. Secondly, the optimal selection of shape from 6 basic shapes for a reciprocating oscillating head-type oscillator. A numerical analysis tool for fluid structure-coupled problems—ANSYS—was used to select the optimum softness of material for the first type of oscillator and the best shape for the second type of oscillator, based on the exhibition of high lift coefficients. For a wing-type oscillator, an optimum elastic modulus for an air-foil was found. For a self-induced vibration-type mechanism, based on analysis of vorticity and velocity distribution, a square-shaped head exhibited a lift coefficient of more than two times that of a cylindrically shaped head. Analysis of the flow field clearly showed that the discontinuous flow caused by a square-headed oscillator results in
Dubus, G.; Lamberts, A.; Fromang, S.
2015-09-01
Context. Detailed modelling of the high-energy emission from gamma-ray binaries has been propounded as a path to pulsar wind physics. Aims: Fulfilling this ambition requires a coherent model of the flow and its emission in the region where the pulsar wind interacts with the stellar wind of its companion. Methods: We have developed a code that follows the evolution and emission of electrons in the shocked pulsar wind based on inputs from a relativistic hydrodynamical simulation. The code is used to model the well-documented spectral energy distribution and orbital modulations from LS 5039. Results: The pulsar wind is fully confined by a bow shock and a back shock. The particles are distributed into a narrow Maxwellian, emitting mostly GeV photons, and a power law radiating very efficiently over a broad energy range from X-rays to TeV gamma rays. Most of the emission arises from the apex of the bow shock. Doppler boosting shapes the X-ray and very high energy (VHE) lightcurves, constraining the system inclination to i ≈ 35°. There is tension between the hard VHE spectrum and the level of X-ray to MeV emission, which requires differing magnetic field intensities that are hard to achieve with constant magnetisation σ and Lorentz factor Γp of the pulsar wind. Our best compromise implies σ ≈ 1 and Γp ≈ 5 × 103, so respectively higher and lower than the typical values in pulsar wind nebulae. Conclusions: The high value of σ derived here, where the wind is confined close to the pulsar, supports the classical picture that has pulsar winds highly magnetised at launch. However, such magnetisations will require that further investigations are based on relativistic MHD simulations. Movies associated to Figs. A.1-A.4 are available in electronic form at http://www.aanda.org
Numerical analysis of radial inward flow turbine for CO2 based closed loop Brayton cycle
Kisan, Jadhav Amit; Govardhan, M.
2017-06-01
Last few decades have witnessed a phenomenal growth in the demand for power, which has driven the suppliers to find new sources of energy and increase the efficiency of power generation process. Power generation cycles are either steam based Rankine cycle or closed loop Brayton cycles providing an efficiency of 30 to 40%. An upcoming technology in this regard is the CO2 based Brayton cycle operating near the critical region which has applications in vast areas. Power generation of CO2 based Brayton cycle can vary from few kilowatts for waste heat recovery to hundreds of megawatts in sodium cooled fast reactors. A CO2 based Brayton cycle is being studied for power generation especially in mid-sized concentrated solar power plants by numerous research groups around the world. One of the main components of such a setting is its turbine. Simulating the flow conditions inside the turbine becomes very crucial in order to accurately predict the performance of the system. The flow inside radial inflow turbine is studied at various inlet temperatures and mass flow rates in order to predict the behavior of the turbine under various boundary conditions. The performance investigation of the turbine system is done on the basis of parameters such as total efficiency, pressure ratio, and power coefficient. Effect of different inlet stagnation temperature and exit mass flow rates on these parameters is also studied. Results obtained are encouraging for the use of CO2 as working fluid in Brayton cycle.
Hybrid Biogeography Based Optimization for Constrained Numerical and Engineering Optimization
Directory of Open Access Journals (Sweden)
Zengqiang Mi
2015-01-01
Full Text Available Biogeography based optimization (BBO is a new competitive population-based algorithm inspired by biogeography. It simulates the migration of species in nature to share information. A new hybrid BBO (HBBO is presented in the paper for constrained optimization. By combining differential evolution (DE mutation operator with simulated binary crosser (SBX of genetic algorithms (GAs reasonably, a new mutation operator is proposed to generate promising solution instead of the random mutation in basic BBO. In addition, DE mutation is still integrated to update one half of population to further lead the evolution towards the global optimum and the chaotic search is introduced to improve the diversity of population. HBBO is tested on twelve benchmark functions and four engineering optimization problems. Experimental results demonstrate that HBBO is effective and efficient for constrained optimization and in contrast with other state-of-the-art evolutionary algorithms (EAs, the performance of HBBO is better, or at least comparable in terms of the quality of the final solutions and computational cost. Furthermore, the influence of the maximum mutation rate is also investigated.
Dongarra, Jack
2012-11-01
We propose to study the impact on the energy footprint of two advanced algorithmic strategies in the context of high performance dense linear algebra libraries: (1) mixed precision algorithms with iterative refinement allow to run at the peak performance of single precision floating-point arithmetic while achieving double precision accuracy and (2) tree reduction technique exposes more parallelism when factorizing tall and skinny matrices for solving over determined systems of linear equations or calculating the singular value decomposition. Integrated within the PLASMA library using tile algorithms, which will eventually supersede the block algorithms from LAPACK, both strategies further excel in performance in the presence of a dynamic task scheduler while targeting multicore architecture. Energy consumption measurements are reported along with parallel performance numbers on a dual-socket quad-core Intel Xeon as well as a quad-socket quad-core Intel Sandy Bridge chip, both providing component-based energy monitoring at all levels of the system, through the Power Pack framework and the Running Average Power Limit model, respectively. © 2012 IEEE.
Deng, Yongfeng; Jiang, Jian; Han, Xianwei; Tan, Chang; Wei, Jianguo
2017-04-01
The problem of flow active control by low temperature plasma is considered to be one of the most flourishing fields of aerodynamics due to its practical advantages. Compared with other means, the electron beam plasma is a potential flow control method for large scale flow. In this paper, a computational fluid dynamics model coupled with a multi-fluid plasma model is established to investigate the aerodynamic characteristics induced by electron beam plasma. The results demonstrate that the electron beam strongly influences the flow properties, not only in the boundary layers, but also in the main flow. A weak shockwave is induced at the electron beam injection position and develops to the other side of the wind tunnel behind the beam. It brings additional energy into air, and the inducing characteristics are closely related to the beam power and increase nonlinearly with it. The injection angles also influence the flow properties to some extent. Based on this research, we demonstrate that the high energy electron beam air plasma has three attractive advantages in aerodynamic applications, i.e. the high energy density, wide action range and excellent action effect. Due to the rapid development of near space hypersonic vehicles and atmospheric fighters, by optimizing the parameters, the electron beam can be used as an alternative means in aerodynamic steering in these applications.
Numerical analysis of modeling based on improved Elman neural network.
Jie, Shao; Li, Wang; WeiSong, Zhao; YaQin, Zhong; Malekian, Reza
2014-01-01
A modeling based on the improved Elman neural network (IENN) is proposed to analyze the nonlinear circuits with the memory effect. The hidden layer neurons are activated by a group of Chebyshev orthogonal basis functions instead of sigmoid functions in this model. The error curves of the sum of squared error (SSE) varying with the number of hidden neurons and the iteration step are studied to determine the number of the hidden layer neurons. Simulation results of the half-bridge class-D power amplifier (CDPA) with two-tone signal and broadband signals as input have shown that the proposed behavioral modeling can reconstruct the system of CDPAs accurately and depict the memory effect of CDPAs well. Compared with Volterra-Laguerre (VL) model, Chebyshev neural network (CNN) model, and basic Elman neural network (BENN) model, the proposed model has better performance.
Lifecycle-Based Swarm Optimization Method for Numerical Optimization
Directory of Open Access Journals (Sweden)
Hai Shen
2014-01-01
Full Text Available Bioinspired optimization algorithms have been widely used to solve various scientific and engineering problems. Inspired by biological lifecycle, this paper presents a novel optimization algorithm called lifecycle-based swarm optimization (LSO. Biological lifecycle includes four stages: birth, growth, reproduction, and death. With this process, even though individual organism died, the species will not perish. Furthermore, species will have stronger ability of adaptation to the environment and achieve perfect evolution. LSO simulates Biological lifecycle process through six optimization operators: chemotactic, assimilation, transposition, crossover, selection, and mutation. In addition, the spatial distribution of initialization population meets clumped distribution. Experiments were conducted on unconstrained benchmark optimization problems and mechanical design optimization problems. Unconstrained benchmark problems include both unimodal and multimodal cases the demonstration of the optimal performance and stability, and the mechanical design problem was tested for algorithm practicability. The results demonstrate remarkable performance of the LSO algorithm on all chosen benchmark functions when compared to several successful optimization techniques.
Numerical Analysis of Modeling Based on Improved Elman Neural Network
Directory of Open Access Journals (Sweden)
Shao Jie
2014-01-01
Full Text Available A modeling based on the improved Elman neural network (IENN is proposed to analyze the nonlinear circuits with the memory effect. The hidden layer neurons are activated by a group of Chebyshev orthogonal basis functions instead of sigmoid functions in this model. The error curves of the sum of squared error (SSE varying with the number of hidden neurons and the iteration step are studied to determine the number of the hidden layer neurons. Simulation results of the half-bridge class-D power amplifier (CDPA with two-tone signal and broadband signals as input have shown that the proposed behavioral modeling can reconstruct the system of CDPAs accurately and depict the memory effect of CDPAs well. Compared with Volterra-Laguerre (VL model, Chebyshev neural network (CNN model, and basic Elman neural network (BENN model, the proposed model has better performance.
Energy-based analysis of biomolecular pathways.
Gawthrop, Peter J; Crampin, Edmund J
2017-06-01
Decomposition of biomolecular reaction networks into pathways is a powerful approach to the analysis of metabolic and signalling networks. Current approaches based on analysis of the stoichiometric matrix reveal information about steady-state mass flows (reaction rates) through the network. In this work, we show how pathway analysis of biomolecular networks can be extended using an energy-based approach to provide information about energy flows through the network. This energy-based approach is developed using the engineering-inspired bond graph methodology to represent biomolecular reaction networks. The approach is introduced using glycolysis as an exemplar; and is then applied to analyse the efficiency of free energy transduction in a biomolecular cycle model of a transporter protein [sodium-glucose transport protein 1 (SGLT1)]. The overall aim of our work is to present a framework for modelling and analysis of biomolecular reactions and processes which considers energy flows and losses as well as mass transport.
Energy information data base. Subject thesaurus
Energy Technology Data Exchange (ETDEWEB)
1978-06-01
The technical staff of the DOE Technical Information Center, during its subject indexing activities, develops and structures a vocabulary that allows consistent machine storage and retrieval of information necessary to the accomplishment of the DOE mission. This thesaurus incorporates that structured vocabulary. The terminology of this thesaurus is used for the subject control of information announced in DOE Energy Research Abstracts, Energy Abstracts for Policy Analysis, Solar Energy Update, Geothermal Energy Update, Fossil Energy Update, Fusion Energy Update, Energy Conservation Update, and Power Reactor Docket Information (published for the Nuclear Regulatory Commission). This terminology also facilitates subject searching of the DOE technical information data base, a research in progress data base describing energy-related research, and a general and practical energy information data base on the DOE on-line retrieval system, RECON. The rapid expansion of DOE's activities will result in a concomitant thesaurus expansion as information relating to new activities is indexed. Only the terms used in indexing documents at the Technical Information Center to date are included. (RWR)
Base Program on Energy Related Research
Energy Technology Data Exchange (ETDEWEB)
Western Research Institute
2008-06-30
The main objective of the Base Research Program was to conduct both fundamental and applied research that will assist industry in developing, deploying, and commercializing efficient, nonpolluting fossil energy technologies that can compete effectively in meeting the energy requirements of the Nation. In that regard, tasks proposed under the WRI research areas were aligned with DOE objectives of secure and reliable energy; clean power generation; development of hydrogen resources; energy efficiency and development of innovative fuels from low and no-cost sources. The goal of the Base Research Program was to develop innovative technology solutions that will: (1) Increase the production of United States energy resources--coal, natural gas, oil, and renewable energy resources; (2) Enhance the competitiveness of United States energy technologies in international markets and assist in technology transfer; (3) Reduce the nation's dependence on foreign energy supplies and strengthen both the United States and regional economies; and (4) Minimize environmental impacts of energy production and utilization. This report summarizes the accomplishments of the overall Base Program. This document represents a stand-alone Final Report for the entire Program. It should be noted that an interim report describing the Program achievements was prepared in 2003 covering the progress made under various tasks completed during the first five years of this Program.
Skiba, Yuri N.; Filatov, Denis M.
2017-12-01
A detailed analysis of a new method for numerical simulation of nonlinear diffusion phenomena is carried out. The method is based on operator splitting performed in time and space, and yields highly accurate solutions in complex 2D and 3D computational domains. After providing a circumstantial mathematical description of the developed method, we test it in several numerical experiments aimed, firstly, to model energy transfer at diverse modes of evolution of the dynamical system, and, secondly, to simulate self-organisation processes typical for real-world applications. A discussion of the outcomes of the numerical experiments is given. This is a follow-up paper of our recent original results presented at the 19th European conference on mathematics for industry.
National Research Council Canada - National Science Library
Jiwei Song; Ye Yuan; Sui Gu; Xianyu Yang; Ye Yue; Jihua Cai; Guosheng Jiang
2017-01-01
...) on Atoka shale samples, this paper reports the numerical simulation findings of wellbore stability in the presence of NP based drilling fluid, using the 2D fluid-solid coupling model in FLAC3D™ software...
Acoustic Focusing and Energy Confinement Based on Multilateral Metasurfaces
Qi, Shuibao; Li, Yong; Assouar, Badreddine
2017-05-01
Metamaterial-based acoustic wave manipulation shows great potential in effective acoustic energy confinement and low-frequency acoustic isolation. We numerically and theoretically propose here a concept based on multilateral metasurfaces for reflected acoustic focusing and energy confinement. The theoretical phase-shift profile required for reflected wave focusing and governed by the generalized Snell's law can be discretely realized by appropriately arraying the labyrinthine units in the right sequences. Based on this design, multilateral metasurfaces for acoustic wave focusing and energy confinement under point-source incidence are considered and sufficiently investigated. The coupling effects and multiple reflections between or among metasurfaces, which play a significant role in the energy confinement, are initially analyzed and discussed. We show that the acoustic focusing and confinement increase with the sides of the multilateral metasurfaces as anticipated. In addition to the contribution of the first reflection, multiple reflections also contribute to the acoustic focusing and energy confinement, especially when the metasurfaces are configured in parallel. The proposed multilateral metasurfaces should have excellent performance in acoustic energy confinement in various situations due to the variable designs and strong acoustic focusing capabilities.
Directory of Open Access Journals (Sweden)
Xia Xiaozhou
2013-01-01
Full Text Available In the frame of the extended finite element method, the exponent disconnected function is introduced to reflect the discontinuous characteristic of crack and the crack tip enrichment function which is made of triangular basis function, and the linear polar radius function is adopted to describe the displacement field distribution of elastoplastic crack tip. Where, the linear polar radius function form is chosen to decrease the singularity characteristic induced by the plastic yield zone of crack tip, and the triangle basis function form is adopted to describe the displacement distribution character with the polar angle of crack tip. Based on the displacement model containing the above enrichment displacement function, the increment iterative form of elastoplastic extended finite element method is deduced by virtual work principle. For nonuniform hardening material such as concrete, in order to avoid the nonsymmetry characteristic of stiffness matrix induced by the non-associate flowing of plastic strain, the plastic flowing rule containing cross item based on the least energy dissipation principle is adopted. Finally, some numerical examples show that the elastoplastic X-FEM constructed in this paper is of validity.
Energy conservation and high-frequency damping in numerical time integration
DEFF Research Database (Denmark)
Krenk, Steen
2008-01-01
additional variables to represent damping. In the present paper it is demonstrated, how damping equivalent to the α-damping of the Newmark algorithm can be introduced directly via displacement and velocity dependent terms. It is furthermore shown, how this damping can be improved by introduction of a new set...... this often leads to a fairly large number of high-frequency modes, that are not represented well – and occasionally directly erroneously – by the model. It is desirable to cure this problem by devising algorithms that include the possibility of introducing algorithmic energy dissipation of the high......-frequency modes. The problem is well known from classic collocation based algorithms – notably various forms of the Newmark algorithm – where the equation of motion is supplemented by approximate relations between displacement, velocity and acceleration. Here adjustment of the algorithmic parameters can be used...
Energy conservation and high-frequency damping in numerical time-integration
DEFF Research Database (Denmark)
Krenk, Steen
2007-01-01
by introduction of a new set of variables related to the displacement and velocity vectors by a suitable first order filter with scalar coefficients. By this device an algorithmic damping can be obtained that is of third order in the low-frequency regime. It is an important feature of both algorithms...... this often leads to a fairly large number of high-frequency modes, that are not represented well - and occasionally directly erroneously - by the model. It is desirable to cure this problem by devising algorithms that include the possibility of introducing algorithmic energy dissipation of the high......-frequency modes. The problem is well known from classic collocation based algorithms - notably various forms of the Newmark algorithm where the equation of motion is supplemented by approximate relations between displacement, velocity and acceleration. Here adjustment of the algorithmic parameters can be used...
Numerical methods in finance and economics a MATLAB-based introduction
Brandimarte, Paolo
2006-01-01
A state-of-the-art introduction to the powerful mathematical and statistical tools used in the field of financeThe use of mathematical models and numerical techniques is a practice employed by a growing number of applied mathematicians working on applications in finance. Reflecting this development, Numerical Methods in Finance and Economics: A MATLAB?-Based Introduction, Second Edition bridges the gap between financial theory and computational practice while showing readers how to utilize MATLAB?--the powerful numerical computing environment--for financial applications.The author provides an essential foundation in finance and numerical analysis in addition to background material for students from both engineering and economics perspectives. A wide range of topics is covered, including standard numerical analysis methods, Monte Carlo methods to simulate systems affected by significant uncertainty, and optimization methods to find an optimal set of decisions.Among this book''s most outstanding features is the...
A Numerical Matrix-Based method in Harmonic Studies in Wind Power Plants
DEFF Research Database (Denmark)
Dowlatabadi, Mohammadkazem Bakhshizadeh; Hjerrild, Jesper; Kocewiak, Łukasz Hubert
2016-01-01
In the low frequency range, there are some couplings between the positive- and negative-sequence small-signal impedances of the power converter due to the nonlinear and low bandwidth control loops such as the synchronization loop. In this paper, a new numerical method which also considers...... these couplings will be presented. The numerical data are advantageous to the parametric differential equations, because analysing the high order and complex transfer functions is very difficult, and finally one uses the numerical evaluation methods. This paper proposes a numerical matrix-based method, which...... is not only able to deal with those mentioned numerical data, but also it is able to consider all couplings between the positive and negative sequences....
Numerical thermal back-calculation of the Kerava Solar Village underground thermal energy storage
Oosterbaan, Harm; Janiszewski, Mateusz; Uotinen, Lauri; Siren, Topias; Rinne, Mikael
2017-01-01
With increasing pressure to reduce the fraction of energy coming from fossil fuels, there is an increased need for research into feasible, and sustainable energy sources, such as solar energy. The problem with solar energy is the mismatch between supply and demand, and so the energy needs to be stored. This research paper is a part of the project titled “Tackling the Challenges of a Solar-Community Concept in High Latitudes”, and aims in helping to design a thermal energy storage system for s...
Galgani, Luigi; Giorgilli, Antonio; Martinoli, Andrea; Vanzini, Stefano
1992-11-01
We report on some analytical and numerical results on the exchanges of energy in systems of the Fermi-Pasta-Ulam type, in the light of Nekhoroshev's theorem, with particular attention to the dependence of the estimates on the number n of degrees of freedom. For the ordinary FPU problem we look for a control of the single normal mode energies, and we find both the analytical and numerical estimates to agree in predicting that the energy exchanges of the single modes cannot be controlled in the thermodynamic limit. We consider then a modified FPU model, with alternating light and heavy particles, which appears as composed of two subsystems, of low (acoustic) frequency and of high (optical) frequency respectively. We try to control the exchange of the total energy of the high frequency modes up to times increasing exponentially with the frequency. In this case the numerical estimates are stronger than the available analytical ones, and give indications for nonequipartition with constants essentially independent of the number n of degrees of freedom.
Directory of Open Access Journals (Sweden)
Dede Tarwidi
2016-11-01
Full Text Available In this paper, thermal performance of various phase change materials (PCMs used as thermal energy storage in a solar cooker has been investigated numerically. Heat conduction equations in cylindrical domain are used to model heat transfer of the PCMs. Mathematical model of phase change problem in the PCM storage encompasses heat conduction equations in solid and liquid region separated by moving solid-liquid interface. The phase change problem is solved by reformulating heat conduction equations with emergence of moving boundary into an enthalpy equation. Numerical solution of the enthalpy equation is obtained by implementing Godunov method and verified by analytical solution of one-dimensional case. Stability condition of the numerical scheme is also discussed. Thermal performance of various PCMs is evaluated via the stored energy and temperature history. The simulation results show that phase change material with the best thermal performance during the first 2.5 hours of energy extraction is shown by erythritol. Moreover, magnesium chloride hexahydrate can maintain temperature of the PCM storage in the range of 110-116.7°C for more than 4 hours while magnesium nitrate hexahydrate is effective only for one hour with the PCM storage temperature around 121-128°C. Among the PCMs that have been tested, it is only erythritol that can cook 10 kg of the loaded water until it reaches 100°C for about 3.5 hours. Article History: Received June 22nd 2016; Received in revised form August 26th 2016; Accepted Sept 1st 2016; Available online How to Cite This Article: Tarwidi, D., Murdiansyah, D.T, Ginanja, N. (2016 Performance Evaluation of Various Phase Change Materials for Thermal Energy Storage of A Solar Cooker via Numerical Simulation. Int. Journal of Renewable Energy Development, 5(3, 199-210. http://dx.doi.org/10.14710/ijred.5.3.199-210
Ignat'ev, Yu G
2016-01-01
In this paper we investigate the asymptotic behavior of the cosmological model based on phantom scalar field on the ground of qualitative analysis of the system of the cosmological model's differential equations and show that as opposed to models with classical scalar field, such models have stable asymptotic solutions with constant value of the potential both in infinite past and infinite future. We also develop numerical models of the cosmological evolution models with phantom scalar field in this paper. {\\bf keywords}: cosmological model, phantom scalar field, quality analysis, asymptotic behavior, numerical simulation, numerical gravitation.\\\\ {\\bf PACS}: 04.20.Cv, 98.80.Cq, 96.50.S 52.27.Ny
Directory of Open Access Journals (Sweden)
M. V. A. Lima
Full Text Available This work presents a model to predict the flexural behavior of reinforced concrete slabs, combining the Mazars damage model for simulation of the loss of stiffness of the concrete during the cracking process and the Classical Theory of Laminates, to govern the bending of the structural element. A variational formulation based on the principle of virtual work was developed for the model, and then treated numerically according to the Finite Difference Energy Method, with the end result a program developed in Fortran. To validate the model thus proposed have been simulated with the program, some cases of slabs in flexure in the literature. The evaluation of the results obtained in this study demonstrated the capability of the model, in view of the good predictability of the behavior of slabs in flexure, sweeping the path of equilibrium to the rupture of the structural element. Besides the satisfactory prediction of the behavior observed as positive aspects of the model to its relative simplicity and reduced number of experimental parameters necessary for modeling.
Energy-Based Metrics for Arthroscopic Skills Assessment.
Poursartip, Behnaz; LeBel, Marie-Eve; McCracken, Laura C; Escoto, Abelardo; Patel, Rajni V; Naish, Michael D; Trejos, Ana Luisa
2017-08-05
Minimally invasive skills assessment methods are essential in developing efficient surgical simulators and implementing consistent skills evaluation. Although numerous methods have been investigated in the literature, there is still a need to further improve the accuracy of surgical skills assessment. Energy expenditure can be an indication of motor skills proficiency. The goals of this study are to develop objective metrics based on energy expenditure, normalize these metrics, and investigate classifying trainees using these metrics. To this end, different forms of energy consisting of mechanical energy and work were considered and their values were divided by the related value of an ideal performance to develop normalized metrics. These metrics were used as inputs for various machine learning algorithms including support vector machines (SVM) and neural networks (NNs) for classification. The accuracy of the combination of the normalized energy-based metrics with these classifiers was evaluated through a leave-one-subject-out cross-validation. The proposed method was validated using 26 subjects at two experience levels (novices and experts) in three arthroscopic tasks. The results showed that there are statistically significant differences between novices and experts for almost all of the normalized energy-based metrics. The accuracy of classification using SVM and NN methods was between 70% and 95% for the various tasks. The results show that the normalized energy-based metrics and their combination with SVM and NN classifiers are capable of providing accurate classification of trainees. The assessment method proposed in this study can enhance surgical training by providing appropriate feedback to trainees about their level of expertise and can be used in the evaluation of proficiency.
Tariff based value of wind energy
Energy Technology Data Exchange (ETDEWEB)
Raekkoelaeinen, J.; Vilkko, M.; Antila, H.; Lautala, P. [Tampere Univ. of Technology (Finland)
1995-12-31
In this article an approach for determining a value of wind energy is presented. Calculation is based on wholesale tariffs, i.e. the value of wind energy is defined in comparison with other purchase. This approach can be utilised as an aid in the investment planning in defining the benefits of new wind generation capacity. Linear programming optimization method is used. A case study is presented for different wind scenarios. The value of wind energy can vary remarkably depending on timing of power output. (author)
Mathematical and numerical modeling of the AquaBuOY wave energy converter
Energy Technology Data Exchange (ETDEWEB)
Wacher, A.; Nielsen, K.
2008-12-15
We have introduced a mathematical model of the vertical dynamics of the AquaBuOY's IPS buoy and hose-pump power take off system. The numerical results obtained proved to be very accurate as compared to real life data of Finavera's fiftieth and tenth scales of the AquaBuOY. The numerical implementation of the model is extremely fast for the regular wave regime and nearly real time for the irregular wave regime, however the results in the irregular wave regime are far more accurate than for regular waves. The model and method have proved to be robust, efficient and accurate however future work is recommended in the time integration scheme used to solve the ordinary differential equations in the irregular wave regime as it would be useful for optimization over many variables to make the numerical integration faster. (Author)
Directory of Open Access Journals (Sweden)
Yi Li
2017-01-01
Full Text Available With the blossoming of intermittent energy, compressed air energy storage (CAES has attracted much attention as a potential large-scale energy storage technology. Compared with caverns as storage vessels, compressed air energy storage in aquifers (CAESA has the advantages of wide availability and lower costs. The wellbore can play an important role as the energy transfer mechanism between the surroundings and the air in CAESA system. In this paper, we investigated the influences of the well screen length on CAESA system performance using an integrated wellbore-reservoir simulator (T2WELL/EOS3. The results showed that the well screen length can affect the distribution of the initial gas bubble and that a system with a fully penetrating wellbore can obtain acceptably stable pressurized air and better energy efficiencies. Subsequently, we investigated the impact of the energy storage scale and the target aquifer depth on the performance of a CAESA system using a fully penetrating wellbore. The simulation results demonstrated that larger energy storage scales exhibit better performances of CAESA systems. In addition, deeper target aquifer systems, which could decrease the energy loss by larger storage density and higher temperature in surrounding formation, can obtain better energy efficiencies.
Jin, Y.; Kuznetsov, A. V.
2017-04-01
Various models are available for simulating turbulent flows in porous media. Models based on the eddy viscosity assumption are often adopted to close the Reynolds stress term. In order to validate the assumptions behind such turbulence models, we studied the dynamics of macroscopic momentum and turbulence kinetic energy in porous media flows by utilizing Direct Numerical Simulation (DNS). The generic porous matrix is composed of regularly arranged spheres. The resulting periodic porous medium is bounded by two walls. The DNS analyses with a Lattice Boltzmann method were performed for various values of the applied pressure gradient, pore size to channel width ratio, and porosity. The DNS results were averaged over time and volume to obtain macroscopic results. The results show that the macroscopic shear Reynolds stress in all Representative Elementary Volumes (REVs), independent of their location, is negligibly small, although the mean velocity gradient takes nonzero values near the wall. The turbulence kinetic energy production rate is generally balanced by the dissipation rate in each REV. The DNS results support a zero-equation turbulence model that accounts for the fact that turbulent structures are restricted in size by the pore scale. The DNS results also suggest that the Brinkman term, which expresses the diffusion of momentum, has an important effect near the wall where the gradient of the shear stress is large. Therefore, the Brinkman term should be taken into account in the macroscopic momentum equation as a component of the total drag. A preliminary macroscopic model for calculating turbulent porous media flows has been proposed and compared with our DNS results.
Energy Technology Data Exchange (ETDEWEB)
Nussbaumer, T.; Oser, M.
2004-07-01
This final report prepared for the International Energy Agency (IEA) Bioenergy Task 32 presents a method for a comparison of different energy systems with respect to the overall energy yield during their life cycles. For this purpose, the Cumulative Energy Demand (CED) based on primary energy and the Energy Yield Factor (EYC) are introduced and determined for the following scenarios: Log wood, wood chips, and wood pellets for residential heating and - except for log wood - also for district heating. As an alternative to heat production, power production via combustion and use of the electricity for decentralised heat pumps is also looked at. The evaluation and comparison of both the EYC for all fuels and the EYC{sub N}R for the non-renewable part enables a ranking of energy systems without a subjective weighing of non-renewable and renewable fuels to be made. For a sustainable energy supply, it is proposed to implement renewable energy systems in future which achieve an energy yield EYC{sub N}R of at least greater than 2 but favourably greater than 5. The evaluation of the different scenarios presented is proposed as the future basis for the choice of the most efficient energy systems based on biomass combustion.
Graphene-Based Systems for Energy Storage
Calle, Carlos I.; Mackey, Paul J.; Johansen, Michael R.; Phillips, James, III; Hogue, Michael; Kaner, Richard B.; El-Kady, Maher
2016-01-01
Development of graphene-based energy storage devices based on the Laser Scribe system developed by the University of California Los Angeles. These devices These graphene-based devices store charge on graphene sheets and take advantage of the large accessible surface area of graphene (2,600 m2g) to increase the electrical energy that can be stored. The proposed devices should have the electrical storage capacity of thin-film-ion batteries but with much shorter charge discharge cycle times as well as longer lives The proposed devices will be carbon-based and so will not have the same issues with flammability or toxicity as the standard lithium-based storage cells.
Directory of Open Access Journals (Sweden)
M Virk
2016-08-01
Full Text Available Atmospheric icing on wind turbines have been recognized as a hindrance to the development of the wind power in cold regions, where uncertainty surrounding the effects of icing on energy production may prevent otherwise good wind resources from being utilized. This research paper is focused on to numerically simulate the rate and shape of atmospheric ice accretion on a full-scale horizontal axis wind turbine blade. Computational fluid dynamics based multiphase numerical analyses have been carried out where results showed a decrease in atmospheric ice growth rate along leading edge with the increase of blade profile size, both in terms of local ice mass and thickness. Streamlined ice shapes were observed near the blade root section, as compared to the blade tip section.
A GIS-based numerical simulation of the March 2014 Oso landslide fluidized motion
Fukuoka, H.; Ogbonnaya, I.; Wang, C.
2014-12-01
Sliding and flowing are the major movement type after slope failures. Landslides occur when slope-froming material moves downhill after failing along a sliding surface. Most debris flows originally occur in the form of rainfall-induced landslides before they move into valley channel. Landslides that mobilize into debris flows usually are characterized by high-speed movement and long run-out distance and may present the greatest risk to human life. The 22 March 2014 Oso landslide is a typical case of landside transformint to debris flow. The landslide was triggered on the edge of a plateau about 200 m high composed of glacial sediments after excessive prolonged rainfall of 348 in March 2014. After its initiation, portions of the landslide materials transitioned into a rapidly moving debris flow which traveled long distances across the downslope floodplain. U.S. Geological Survey estimated the volume of the slide to be about 7 million m3, and it traveled about 1 km from the toe of the slope. The apparent friction angle measured by the energy line drawn from the crown of the head scarp to the toe of the deposits which reached largest distance, was only 5~6 degrees. we performed two numerical modeling to predicting the runout distance and to get insight into the behaviour of the landslide movement. One is GIS-based revised Hovland's 3D limit equilibrium model which is used to simulate the movement and stoppage of a landslide. In this research, sliding is defined by a slip surface which cuts through the slope, causing the mass of earth to move above it. The factor of safety will be calculated step by step during the sliding process simulation. Stoppage is defined by the factor of safety much greater than one and the velocity equal zero. The other is GIS-based depth-averaged 2D numerical model using a coupled viscous and Coulomb type law to simulate a debris flow from initiation to deposition. We compared our simulaiton results with the results of preliminary computer
The effect of numerical techniques on differential equation based chaotic generators
Zidan, Mohammed A.
2012-07-29
In this paper, we study the effect of the numerical solution accuracy on the digital implementation of differential chaos generators. Four systems are built on a Xilinx Virtex 4 FPGA using Euler, mid-point, and Runge-Kutta fourth order techniques. The twelve implementations are compared based on the FPGA used area, maximum throughput, maximum Lyapunov exponent, and autocorrelation confidence region. Based on circuit performance and the chaotic response of the different implementations, it was found that less complicated numerical solution has better chaotic response and higher throughput.
Electromagnetic ferrofluid-based energy harvester
Energy Technology Data Exchange (ETDEWEB)
Bibo, A.; Masana, R.; King, A.; Li, G. [Nonlinear Vibrations and Energy Harvesting Laboratory (NOVEHL), Department of Mechanical Engineering, Clemson University, Clemson, SC 29634 (United States); Daqaq, M.F., E-mail: mdaqaq@clemson.edu [Nonlinear Vibrations and Energy Harvesting Laboratory (NOVEHL), Department of Mechanical Engineering, Clemson University, Clemson, SC 29634 (United States)
2012-06-25
This Letter investigates the use of ferrofluids for vibratory energy harvesting. In particular, an electromagnetic micro-power generator which utilizes the sloshing of a ferrofluid column in a seismically-excited tank is proposed to transform mechanical motions directly into electricity. Unlike traditional electromagnetic generators that implement a solid magnet, ferrofluids can easily conform to different shapes and respond to very small acceleration levels offering an untapped opportunity to design scalable energy harvesters. The feasibility of the proposed concept is demonstrated and its efficacy is discussed through several experimental studies. -- Highlights: ► A ferrofluid-based electromagnetic energy harvester is proposed and tested. Conformability of fluids offers unique capabilities to design scalable harvesters. ► Power is sensitive to changes in the fluid surface area and external magnetization. ► Device generates 1 microwatt of output power at a base acceleration of 3 m/s{sup 2}.
Tall Tower Wind Energy Monitoring and Numerical Model Validation in Northern Nevada
Energy Technology Data Exchange (ETDEWEB)
Koracin, D. [Desert Research Inst. (DRI), Las Vegas, NV (United States); Kaplan, M. [Desert Research Inst. (DRI), Las Vegas, NV (United States); Smith, C. [Desert Research Inst. (DRI), Las Vegas, NV (United States); McCurdy, G. [Desert Research Inst. (DRI), Las Vegas, NV (United States); Wolf, A. [Desert Research Inst. (DRI), Las Vegas, NV (United States); McCord, T. [Desert Research Inst. (DRI), Las Vegas, NV (United States); King, K. [Desert Research Inst. (DRI), Las Vegas, NV (United States); Belu, R. [Drexel Univ., Philadelphia, PA (United States); Horvath, K. [Croatian Meteorological and Hydrological Service, Zagreb (Croatia)
2015-10-01
The main objectives of this project were to conduct a tall-tower and sodar field campaign in complex terrain, investigate wind properties relevant to wind energy assessment, and evaluate high-resolution models with fixed and adaptive grid structures. Two 60-m towers at Virginia Peak ridges near Washoe Valley, Nevada, were instrumented with cup and vane anemometers as well as sonic anemometers, and an acoustic sounder (hereafter sodar) was installed near one of the towers. The towers were located 2,700 m apart with a vertical distance of 140 m elevation between their bases. Each tower had a downhill exposure of rolling complex terrain, with the nearby valley floor 3,200 m to the west and 800 m below the summit. Cup anemometers were installed at both towers at 20, 40, and 60 m, wind vanes at 20 and 60 m, and sonic anemometers at 20 and 60 m. The sodar measurements were nominally provided every 10 m in vertical distance from 40 to 200 m with the quality of the data generally decreasing with height. Surface air temperature, atmospheric pressure, and radiation measurements were conducted at 1.5 m AGL at both of the towers. Although the plan was to conduct a 1-year period of data collection, we extended the period (October 5, 2012 through February 24, 2014) to cover for possible data loss from instrument or communication problems. We also present a preliminary analysis of the towers and sodar data, including a detailed inventory of available and missing data as well as outliers. The analysis additionally includes calculation of the Weibull parameters, turbulence intensity, and initial computation of wind power density at various heights.
Numerical Simulations of the Kinetic Energy Transfer in the Bath of a BOF Converter
Zhou, Xiaobin; Ersson, Mikael; Zhong, Liangcai; Jönsson, Pär
2016-02-01
The paper focuses on the fundamental aspects of the kinetic energy transfer from a top and bottom gas injection to the bath of the basic oxygen furnace (BOF) by applying a mathematical model. The analyses revealed that the energy transfer is less efficient when top lance height is lowered or the flowrate is increased in the top blowing operations. However, an inverse trend was found that the kinetic energy transfer is increased when the bottom flowrate is increased for the current bottom blowing operation conditions. The kinetic energy transfer index results indicated that the energy transfer for the bottom blowing is much more efficient than that of the top blowing operations. To understand the effects of the upper buoyant phase on the energy dissipation of the bulk liquid in the bath, different mass and physical properties of slag and foam were considered in the bottom blowing simulations. The slag on top of the bath is found to dissipate by 6.6, 9.4, and 11.2 pct for slag mass values of 5, 9, and 15 t compared to the case without slag atop the surface of the bath, respectively. The results showed that the kinetic energy transfer is not largely influenced by the viscosity of the upper slag or the foaming phases.
Chidananda, H.; Reddy, T. Hanumantha
2017-06-01
This paper presents a natural representation of numerical digit(s) using hand activity analysis based on number of fingers out stretched for each numerical digit in sequence extracted from a video. The analysis is based on determining a set of six features from a hand image. The most important features used from each frame in a video are the first fingertip from top, palm-line, palm-center, valley points between the fingers exists above the palm-line. Using this work user can convey any number of numerical digits using right or left or both the hands naturally in a video. Each numerical digit ranges from 0 to9. Hands (right/left/both) used to convey digits can be recognized accurately using the valley points and with this recognition whether the user is a right / left handed person in practice can be analyzed. In this work, first the hand(s) and face parts are detected by using YCbCr color space and face part is removed by using ellipse based method. Then, the hand(s) are analyzed to recognize the activity that represents a series of numerical digits in a video. This work uses pixel continuity algorithm using 2D coordinate geometry system and does not use regular use of calculus, contours, convex hull and datasets.
Le Touz, Nicolas; Dumoulin, Jean
2015-04-01
Facing the heavy organisational, financial and environmental constraints imposed by usual winter maintenance salting operations, pavement engineers have been led to look for alternative solutions to avoid ice or snow deposit at pavements surface. Among the solutions, one is self-de-icing heating pavements, for which two technologies have been developed so far: one is based on embedded coils circulating a heated calorific fluid under the pavement surface; the other one relies on the use of embedded resistant electric wires. The use and operation of such systems in the world is still limited and was only confined to small road stretches or specific applications, such as bridges which are particularly sensitive to frost. One of the most significant "coil technology" example in Europe is the SERSO-System (Solar Energy recovery from road surfaces) built in 1994, on a Switzerland bridge. Many of these experiences are referenced in the technical literature, which provides state-of-the art papers (see for instance Eugster) and useful detailed information dealing with the construction and operational management of such installation. The present study is taking part of the Forever Open Road Concept addressed by the R5G: 5th Generation Road [1], one of the major project supported by IFSTTAR. It considers a different design of self-de-icing road that simplify its mode of construction and maintenance, compared to the two technologies mentioned above. It should also be noted that similar to pavements instrumented with coils, such structure could be used in the reversible way to capture the solar energy at the pavement surface during sunny days and store it, to either warm the pavement at a later stage or for exogenous needs (e.g. contribution to domestic hot water). To complete our study we also considered the use of semi-transparent pavement course wearing in place of the traditional opaque one. In the present study, a 2D model was developed using FEM approach. It combines 2
Energy Budget of Forming Clumps In Numerical Simulations of Collapsing Clouds
Camacho, Vianey; Vasquez-Semadeni, E.; Ballesteros-Paredes, J.; Gomez, G.
2017-06-01
We analyze the energy balance of clumps and cores in two SPH simulations of collapsing clouds. We find that: (i) the set of clumps with low column-density shows a large scatter around equipartition which, in more than half of the cases, is dominated by external turbulent compressions that assemble them, (ii) clumps lying in filaments tend to appear sub-virial, (iii) high-density cores that exhibit moderate kinetic energy excesses often contain stellar particles, and (iv) cores with kinetic energy excess but no stellar particles are in a state of dispersal.
Sustainable Urban Regeneration Based on Energy Balance
Directory of Open Access Journals (Sweden)
Sacha Silvester
2012-07-01
Full Text Available In this paper, results are reported of a technology assessment of the use and integration of decentralized energy systems and storage devices in an urban renewal area. First the general context of a different approach based on 'rethinking' and the incorporation of ongoing integration of coming economical and environmental interests on infrastructure, in relation to the sustainable urban development and regeneration from the perspective of the tripod people, technology and design is elaborated. However, this is at different scales, starting mainly from the perspective of the urban dynamics. This approach includes a renewed look at the ‘urban metabolism’ and the role of environmental technology, urban ecology and environment behavior focus. Second, the potential benefits of strategic and balanced introduction and use of decentralized devices and electric vehicles (EVs, and attached generation based on renewables are investigated in more detail in the case study of the ‘Merwe-Vierhaven’ area (MW4 in the Rotterdam city port in the Netherlands. In order to optimize the energy balance of this urban renewal area, it is found to be impossible to do this by tuning the energy consumption. It is more effective to change the energy mix and related infrastructures. However, the problem in existing urban areas is that often these areas are restricted to a few energy sources due to lack of available space for integration. Besides this, energy consumption in most cases is relatively concentrated in (existing urban areas. This limits the potential of sustainable urban regeneration based on decentralized systems, because there is no balanced choice regarding the energy mix based on renewables and system optimization. Possible solutions to obtain a balanced energy profile can come from either the choice to not provide all energy locally, or by adding different types of storage devices to the systems. The use of energy balance based on renewables as a
Sustainable urban regeneration based on energy balance
Van Timmeren, A.; Zwetsloot, J.; Brezet, H.; Silvester, S.
2012-01-01
In this paper, results are reported of a technology assessment of the use and integration of decentralized energy systems and storage devices in an urban renewal area. First the general context of a different approach based on 'rethinking' and the incorporation of ongoing integration of coming
Graphene based materials: Enhancing solar energy harvesting
Energy Technology Data Exchange (ETDEWEB)
Gua, Chun Xian; Guai, Guan Hong; Li, Chang Ming [Nanyang Tecnological Univ., Singapore (Singapore). Center for Advanded Bioanaosystems
2011-05-15
Due to their excellent electronic and physiochemical properties, graphene based materials have been extensively explored for solar energy harvesting as either electron and hole transport materials, buffer layers, or window and counter electrodes. This research news surveys very recent advances in this emerging field with emphasis on fundamental understanding of their enhancement mechanism, while discussing future challenges.
Synthesis of Numerical Methods for Modeling Wave Energy Converter-Point Absorbers: Preprint
Energy Technology Data Exchange (ETDEWEB)
Li, Y.; Yu, Y. H.
2012-05-01
During the past few decades, wave energy has received significant attention among all ocean energy formats. Industry has proposed hundreds of prototypes such as an oscillating water column, a point absorber, an overtopping system, and a bottom-hinged system. In particular, many researchers have focused on modeling the floating-point absorber as the technology to extract wave energy. Several modeling methods have been used such as the analytical method, the boundary-integral equation method, the Navier-Stokes equations method, and the empirical method. However, no standardized method has been decided. To assist the development of wave energy conversion technologies, this report reviews the methods for modeling the floating-point absorber.
Comparative numerical and experimental study of two combined wind and wave energy concepts
Gao, Zhen; Moan, Torgeir; Wan, Ling; Michailides, Constantine
2016-01-01
With a successful and rapid development of offshore wind industry and increased research activities on wave energy conversion in recent years, there is an interest in investigating the technological and economic feasibility of combining offshore wind turbines (WTs) with wave energy converters (WECs). In the EU FP7 MARINA Platform project, three floating combined concepts, namely the spar torus combination (STC), the semi-submersible flap combination (SFC) and the oscillating water column (OWC...
Performance of Numerical Boundary Condition based on Active Wave Absorption System
DEFF Research Database (Denmark)
Trouch, P.; Rouck, J. de; Frigaard, Peter
2001-01-01
The implementation and performance of a new active wave generating‐absorbing boundary condition for a numerical model based on the Volume Of Fluid (VOF) method for tracking free surfaces is presented. This numerical boundary condition AWAVOF is based on an active wave absorption system...... that was first developed in the context of physical wave flume experiments, using a wave paddle. The method applies to regular and irregular waves. Velocities are measured at one location inside the computational domain. The reflected wave train is separated from the incident wave field in front of a structure...... by means of digital filtering and subsequent superposition of the measured velocity signals. The incident wave signal is corrected, so that the reflected wave is effectively absorbed at the boundary. The effectiveness of the active wave generating‐absorbing boundary condition is proved using numerical...
Andriamananjara, K.; Chevalier, L.; Moulin, N.; Bruchon, J.; Liotier, P.-J.; Drapier, S.
2017-10-01
This study aims to establish a numerical strategy allowing to take into account the capillary and wetting issues, considered on the macroscopic scale as a discontinuity of pressure at the fluid-gas interface, and surface tension force balance at the local scale. This modelling is based on the Brinkman/Darcy and Stokes equations solved by a finite element stabilized method. Specific numerical methods are implemented to deal with the discontinuity of pressure field across the flow front. One of the challenges lies in modelling across scales capillary force effects in infusion-based processes to scale-up rules for flows at the process scale, because the computation cost of numerical simulations at local scales is too not tractable industrially.
A Numerical Methods Course Based on B-Learning: Integrated Learning Design and Follow Up
Cepeda, Francisco Javier Delgado
2013-01-01
Information and communication technologies advance continuously, providing a real support for learning processes. Learning technologies address areas which previously have corresponded to face-to-face learning, while mobile resources are having a growing impact on education. Numerical Methods is a discipline and profession based on technology. In…
Numerical Problems and Agent-Based Models for a Mass Transfer Course
Murthi, Manohar; Shea, Lonnie D.; Snurr, Randall Q.
2009-01-01
Problems requiring numerical solutions of differential equations or the use of agent-based modeling are presented for use in a course on mass transfer. These problems were solved using the popular technical computing language MATLABTM. Students were introduced to MATLAB via a problem with an analytical solution. A more complex problem to which no…
A multiscale numerical study into the cascade of kinetic energy leading to severe local storms
Paine, D. A.; Kaplan, M. L.
1977-01-01
The cascade of kinetic energy from macro- through mesoscales is studied on the basis of a nested grid system used to solve a set of nonlinear differential equations. The kinetic energy cascade and the concentration of vorticity through the hydrodynamic spectrum provide a means for predicting the location and intensity of severe weather from large-scale data sets. A mechanism described by the surface pressure tendency equation proves to be important in explaining how initial middle-tropospheric mass-momentum imbalances alter the low-level pressure field.
Numerical Time Integration Methods for a Point Absorber Wave Energy Converter
DEFF Research Database (Denmark)
Zurkinden, Andrew Stephen; Kramer, Morten
2012-01-01
The objective of this abstract is to provide a review of models for motion simulation of marine structures with a special emphasis on wave energy converters. The time-domain model is applied to a point absorber system working in pitch mode only. The device is similar to the well-known Wavestar...
Virus-based piezoelectric energy generation
Lee, Byung Yang; Zhang, Jinxing; Zueger, Chris; Chung, Woo-Jae; Yoo, So Young; Wang, Eddie; Meyer, Joel; Ramesh, Ramamoorthy; Lee, Seung-Wuk
2012-06-01
Piezoelectric materials can convert mechanical energy into electrical energy, and piezoelectric devices made of a variety of inorganic materials and organic polymers have been demonstrated. However, synthesizing such materials often requires toxic starting compounds, harsh conditions and/or complex procedures. Previously, it was shown that hierarchically organized natural materials such as bones, collagen fibrils and peptide nanotubes can display piezoelectric properties. Here, we demonstrate that the piezoelectric and liquid-crystalline properties of M13 bacteriophage (phage) can be used to generate electrical energy. Using piezoresponse force microscopy, we characterize the structure-dependent piezoelectric properties of the phage at the molecular level. We then show that self-assembled thin films of phage can exhibit piezoelectric strengths of up to 7.8 pm V-1. We also demonstrate that it is possible to modulate the dipole strength of the phage, hence tuning the piezoelectric response, by genetically engineering the major coat proteins of the phage. Finally, we develop a phage-based piezoelectric generator that produces up to 6 nA of current and 400 mV of potential and use it to operate a liquid-crystal display. Because biotechnology techniques enable large-scale production of genetically modified phages, phage-based piezoelectric materials potentially offer a simple and environmentally friendly approach to piezoelectric energy generation.
Virus-based piezoelectric energy generation.
Lee, Byung Yang; Zhang, Jinxing; Zueger, Chris; Chung, Woo-Jae; Yoo, So Young; Wang, Eddie; Meyer, Joel; Ramesh, Ramamoorthy; Lee, Seung-Wuk
2012-05-13
Piezoelectric materials can convert mechanical energy into electrical energy, and piezoelectric devices made of a variety of inorganic materials and organic polymers have been demonstrated. However, synthesizing such materials often requires toxic starting compounds, harsh conditions and/or complex procedures. Previously, it was shown that hierarchically organized natural materials such as bones, collagen fibrils and peptide nanotubes can display piezoelectric properties. Here, we demonstrate that the piezoelectric and liquid-crystalline properties of M13 bacteriophage (phage) can be used to generate electrical energy. Using piezoresponse force microscopy, we characterize the structure-dependent piezoelectric properties of the phage at the molecular level. We then show that self-assembled thin films of phage can exhibit piezoelectric strengths of up to 7.8 pm V(-1). We also demonstrate that it is possible to modulate the dipole strength of the phage, hence tuning the piezoelectric response, by genetically engineering the major coat proteins of the phage. Finally, we develop a phage-based piezoelectric generator that produces up to 6 nA of current and 400 mV of potential and use it to operate a liquid-crystal display. Because biotechnology techniques enable large-scale production of genetically modified phages, phage-based piezoelectric materials potentially offer a simple and environmentally friendly approach to piezoelectric energy generation.
Solution of AntiSeepage for Mengxi River Based on Numerical Simulation of Unsaturated Seepage
Directory of Open Access Journals (Sweden)
Youjun Ji
2014-01-01
Full Text Available Lessening the leakage of surface water can reduce the waste of water resources and ground water pollution. To solve the problem that Mengxi River could not store water enduringly, geology investigation, theoretical analysis, experiment research, and numerical simulation analysis were carried out. Firstly, the seepage mathematical model was established based on unsaturated seepage theory; secondly, the experimental equipment for testing hydraulic conductivity of unsaturated soil was developed to obtain the curve of two-phase flow. The numerical simulation of leakage in natural conditions proves the previous inference and leakage mechanism of river. At last, the seepage control capacities of different impervious materials were compared by numerical simulations. According to the engineering actuality, the impervious material was selected. The impervious measure in this paper has been proved to be effectible by hydrogeological research today.
Dose calculation using a numerical method based on Haar wavelets integration
Energy Technology Data Exchange (ETDEWEB)
Belkadhi, K., E-mail: khaled.belkadhi@ult-tunisie.com [Unité de Recherche de Physique Nucléaire et des Hautes Énergies, Faculté des Sciences de Tunis, Université Tunis El-Manar (Tunisia); Manai, K. [Unité de Recherche de Physique Nucléaire et des Hautes Énergies, Faculté des Sciences de Tunis, Université Tunis El-Manar (Tunisia); College of Science and Arts, University of Bisha, Bisha (Saudi Arabia)
2016-03-11
This paper deals with the calculation of the absorbed dose in an irradiation cell of gamma rays. Direct measurement and simulation have shown that they are expensive and time consuming. An alternative to these two operations is numerical methods, a quick and efficient way can furnish an estimation of the absorbed dose by giving an approximation of the photon flux at a specific point of space. To validate the numerical integration method based on the Haar wavelet for absorbed dose estimation, a study with many configurations was performed. The obtained results with the Haar wavelet method showed a very good agreement with the simulation highlighting good efficacy and acceptable accuracy. - Highlights: • A numerical integration method using Haar wavelets is detailed. • Absorbed dose is estimated with Haar wavelets method. • Calculated absorbed dose using Haar wavelets and Monte Carlo simulation using Geant4 are compared.
Energy Technology Data Exchange (ETDEWEB)
Mehrling, T.J., E-mail: timon.mehrling@desy.de [Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg (Germany); Robson, R.E. [Centre for Quantum Dynamics, School of Natural Sciences, Griffith University, Brisbane (Australia); Erbe, J-H.; Osterhoff, J. [Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg (Germany)
2016-09-01
This paper introduces a semi-analytic numerical approach (SANA) for the rapid computation of the transverse emittance of beams with finite energy spread in plasma wakefield accelerators in the blowout regime. The SANA method is used to model the beam emittance evolution when injected into and extracted from realistic plasma profiles. Results are compared to particle-in-cell simulations, establishing the accuracy and efficiency of the procedure. In addition, it is demonstrated that the tapering of vacuum-to-plasma and plasma-to-vacuum transitions is a viable method for the mitigation of emittance growth of beams during their injection and extraction from and into plasma cells.
Numerical simulations of high-energy flows in accreting magnetic white dwarfs
Van Box Som, Lucile; Falize, É.; Bonnet-Bidaud, J.-M.; Mouchet, M.; Busschaert, C.; Ciardi, A.
2018-01-01
Some polars show quasi-periodic oscillations (QPOs) in their optical light curves that have been interpreted as the result of shock oscillations driven by the cooling instability. Although numerical simulations can recover this physics, they wrongly predict QPOs in the X-ray luminosity and have also failed to reproduce the observed frequencies, at least for the limited range of parameters explored so far. Given the uncertainties on the observed polar parameters, it is still unclear whether simulations can reproduce the observations. The aim of this work is to study QPOs covering all relevant polars showing QPOs. We perform numerical simulations including gravity, cyclotron and bremsstrahlung radiative losses, for a wide range of polar parameters, and compare our results with the astronomical data using synthetic X-ray and optical luminosities. We show that shock oscillations are the result of complex shock dynamics triggered by the interplay of two radiative instabilities. The secondary shock forms at the acoustic horizon in the post-shock region in agreement with our estimates from steady-state solutions. We also demonstrate that the secondary shock is essential to sustain the accretion shock oscillations at the average height predicted by our steady-state accretion model. Finally, in spite of the large explored parameter space, matching the observed QPO parameters requires a combination of parameters inconsistent with the observed ones. This difficulty highlights the limits of one-dimensional simulations, suggesting that multi-dimensional effects are needed to understand the non-linear dynamics of accretion columns in polars and the origins of QPOs.
MEMS-Based Waste Vibrational Energy Harvesters
2013-06-01
low spring constant objective to be achieved. A piezoelectric cantilever beam that is very long and very thin would produce the maximum voltage...California, Berkeley, 2002. [11] A. Kasyap, “Development of MEMS-based piezoelectric cantilever arrays for vibrational energy harvesting,” Gainesville, FL...maximum 200 words) The piezoelectric effect is a phenomenon where strain on a piezoelectric crystal structure causes potential difference at its
Energy Technology Data Exchange (ETDEWEB)
Xie, Yu; Sengupta, Manajit; Deline, Chris
2017-06-27
This paper briefly reviews the National Renewable Energy Laboratory's recent efforts on developing all-sky solar irradiance models for solar energy applications. The Fast All-sky Radiation Model for Solar applications (FARMS) utilizes the simulation of clear-sky transmittance and reflectance and a parameterization of cloud transmittance and reflectance to rapidly compute broadband irradiances on horizontal surfaces. FARMS delivers accuracy that is comparable to the two-stream approximation, but it is approximately 1,000 times faster. A FARMS-Narrowband Irradiance over Tilted surfaces (FARMS-NIT) has been developed to compute spectral irradiances on photovoltaic (PV) panels in 2002 wavelength bands. Further, FARMS-NIT has been extended for bifacial PV panels.
A Lyapunov based approach to energy maximization in renewable energy technologies
Iyasere, Erhun
This dissertation describes the design and implementation of Lyapunov-based control strategies for the maximization of the power captured by renewable energy harnessing technologies such as (i) a variable speed, variable pitch wind turbine, (ii) a variable speed wind turbine coupled to a doubly fed induction generator, and (iii) a solar power generating system charging a constant voltage battery. First, a torque control strategy is presented to maximize wind energy captured in variable speed, variable pitch wind turbines at low to medium wind speeds. The proposed strategy applies control torque to the wind turbine pitch and rotor subsystems to simultaneously control the blade pitch and tip speed ratio, via the rotor angular speed, to an optimum point at which the capture efficiency is maximum. The control method allows for aerodynamic rotor power maximization without exact knowledge of the wind turbine model. A series of numerical results show that the wind turbine can be controlled to achieve maximum energy capture. Next, a control strategy is proposed to maximize the wind energy captured in a variable speed wind turbine, with an internal induction generator, at low to medium wind speeds. The proposed strategy controls the tip speed ratio, via the rotor angular speed, to an optimum point at which the efficiency constant (or power coefficient) is maximal for a particular blade pitch angle and wind speed by using the generator rotor voltage as a control input. This control method allows for aerodynamic rotor power maximization without exact wind turbine model knowledge. Representative numerical results demonstrate that the wind turbine can be controlled to achieve near maximum energy capture. Finally, a power system consisting of a photovoltaic (PV) array panel, dc-to-dc switching converter, charging a battery is considered wherein the environmental conditions are time-varying. A backstepping PWM controller is developed to maximize the power of the solar generating
Chen, Huangxin
2017-09-01
In this paper we consider the energy stability estimates for some fully discrete schemes which both consider time and spatial discretizations for the incompressible Navier–Stokes equations. We focus on three kinds of fully discrete schemes, i.e., the linear implicit scheme for time discretization with the finite difference method (FDM) on staggered grids for spatial discretization, pressure-correction schemes for time discretization with the FDM on staggered grids for the solutions of the decoupled velocity and pressure equations, and pressure-stabilization schemes for time discretization with the FDM on staggered grids for the solutions of the decoupled velocity and pressure equations. The energy stability estimates are obtained for the above each fully discrete scheme. The upwind scheme is used in the discretization of the convection term which plays an important role in the design of unconditionally stable discrete schemes. Numerical results are given to verify the theoretical analysis.
Development of Vibration-Based Piezoelectric Raindrop Energy Harvesting System
Wong, Chin Hong; Dahari, Zuraini
2017-03-01
The trend of finding new means to harvest energy has triggered numerous researches to explore the potential of raindrop energy harvesting. This paper presents an investigation on raindrop energy harvesting which compares the performance of polyvinylidene fluoride (PVDF) cantilever and bridge structure transducers and the development of a raindrop energy harvesting system. The parameters which contribute to the output voltage such as droplet size, droplets released at specific heights and dimensions of PVDF transducers are analyzed. Based on the experimental results, the outcomes have shown that the bridge structure transducer generated a higher voltage than the cantilever. Several dimensions have been tested and it was found that the 30 mm × 4 mm × 25 μm bridge structure transducer generated a relatively high AC open-circuit voltage, which is 4.22 V. The power generated by the bridge transducer is 18 μW across a load of 330 kΩ. The transducer is able to drive up a standard alternative current (AC) to direct current (DC) converter (full-wave bridge rectifier). It generated a DC voltage, V DC of 8.7 mV and 229 pW across a 330 kΩ resistor per drop. It is also capable to generate 9.3 nJ in 20 s from an actual rain event.
Simulation of Piezoelectric Energy Harvester Based on the Vortex Flow
Li, Meng; Wang, Haifeng; Cui, Yiliang; Sun, Kaili
2017-10-01
In this article, numerical research on the fluid-structure interaction between the flexible piezoelectric energy harvester (FPEH) and the Von Karman vortex street forming behind a bluff body is carried out to optimize the oscillation of FPEH to obtain more electrical energy. Using ANSYS Workbench platform, the simulation is performed. The numerical results show that the maximal deformation of the PEH is 1.7428 mm, meanwhile the maximal voltage is 4.6144 V. Besides, these numerical results generated by the ANSYS simulation are in good agreement with the experimental results.
Specific Energy Consumption Prediction Method Based on Machine Tool Power Measurement
Directory of Open Access Journals (Sweden)
Guoyong Zhao
2014-07-01
Full Text Available Accurate prediction on energy consumption in machining is helpful to evaluate process energy characteristics and choose process methods for energy saving. Specific energy consumption expresses the required energy consumption when cutting unit volume material. The Back Propagation (BP neural network prediction method for specific energy consumption in machining is set up in the paper. The prediction method bases on machine tool power signal measurement by power analyzer and shunt sensors. In the developed BP neural network, the input layer neurons include spindle speed, feed rate, depth of cut and material removal rate; and the output layer neurons includes specific energy consumption in machining. The power signal measurement system is built up in the computer numerical control (CNC milling machine tool, and the prediction method for specific energy consumption is tested with cutting data. The prediction results show that the introduced method is effective to predict specific energy consumption in machining.
Building Damage Assessment Using Scenario Based Tsunami Numerical Analysis and Fragility Curves
Directory of Open Access Journals (Sweden)
Khawar Rehman
2016-03-01
Full Text Available A combination of a deterministic approach and fragility analysis is applied to assess tsunami damage caused to buildings. The area selected to validate the model is Imwon Port in Korea. The deterministic approach includes numerical modeling of tsunami propagation in the East Sea following an earthquake on the western coast of Japan. The model is based on the linear shallow-water equations (LSWE augmented with Boussinesq approximation to account for dispersion effects in wave propagation, and coastal wave run-up is modeled by non-linear shallow-water equations (NLSWE. The output from the deterministic model comprises inundation depth. The numerical output is used to perform fragility analysis for buildings vulnerable to flooding by tsunamis in the port area. Recently developed fragility curves—based on the ordinal regression method—are used for damage probability estimates. The extent of structural damage in the areas under a tsunami hazard is identified by the numerical modeling of tsunami features. Our numerical model offers high bathymetric resolution, which enables us to capture flow features at the individual structure level and results in improved estimation of damage probability. This approach can serve as a measure of assessing structure vulnerability for areas with little or no records of tsunami damage and provide planners with a better understanding of structure behavior when a tsunami strikes.
Directory of Open Access Journals (Sweden)
Handlovičová Angela
2016-01-01
Full Text Available In this paper, the numerical solution to the Helmholtz equation with impedance boundary condition, based on the Finite volume method, is discussed. We used the Robin boundary condition using exterior points. Properties of the weak solution to the Helmholtz equation and numerical solution are presented. Further the numerical experiments, comparing the numerical solution with the exact one, and the computation of the experimental order of convergence are presented.
Kadantsev, Evgeny; Fortelius, Carl; Druzhinin, Oleg; Mortikov, Evgeny; Glazunov, Andrey; Zilitinkevich, Sergej
2016-04-01
We examine and validate the EFB turbulence closure model (Zilitinkevich et al., 2013), which is based on the budget equations for basic second moments, namely, two energies: turbulent kinetic energy EK and turbulent potential energy EP, and vertical turbulent fluxes of momentum and potential temperature, τi (i = 1, 2) and Fz. Instead of traditional postulation of down-gradient turbulent transport, the EFB closure determines the eddy viscosity and eddy conductivity from the steady-state version of the budget equations for τi and Fz. Furthermore, the EFB closure involves new prognostic equation for turbulent dissipation time scale tT, and extends the theory to non-steady turbulence regimes accounting for non-gradient and non-local turbulent transports (when the traditional concepts of eddy viscosity and eddy conductivity become generally inconsistent). Our special interest is in asymptotic behavior of the EFB closure in strongly stable stratification. For this purpose, we consider plane Couette flow, namely, the flow between two infinite parallel plates, one of which is moving relative to another. We use a set of Direct Numerical Simulation (DNS) experiments at the highest possible Reynolds numbers for different bulk Richardson numbers (Druzhinin et al., 2015). To demonstrate potential improvements in Numerical Weather Prediction models, we test the new closure model in various idealized cases, varying stratification from the neutral and conventionally neutral to stable (GABLS1) running a test RANS model and HARMONIE/AROME model in single-column mode. Results are compared with DNS and LES (Large Eddy Simulation) runs and different numerical weather prediction models.
A Net Energy-based Analysis for a Climate-constrained Sustainable Energy Transition
Sgouridis, Sgouris; Bardi, Ugo; Csala, Denes
2015-01-01
The transition from a fossil-based energy economy to one based on renewable energy is driven by the double challenge of climate change and resource depletion. Building a renewable energy infrastructure requires an upfront energy investment that subtracts from the net energy available to society. This investment is determined by the need to transition to renewable energy fast enough to stave off the worst consequences of climate change and, at the same time, maintain a sufficient net energy fl...
Cantilever-based electret energy harvesters
Boisseau, S; Ricart, T; Defay, E; Sylvestre, A; 10.1088/0964-1726/20/10/105013
2011-01-01
Integration of structures and functions allowed reducing electric consumptions of sensors, actuators and electronic devices. Therefore, it is now possible to imagine low-consumption devices able to harvest their energy in their surrounding environment. One way to proceed is to develop converters able to turn mechanical energy, such as vibrations, into electricity: this paper focuses on electrostatic converters using electrets. We develop an accurate analytical model of a simple but efficient cantilever-based electret energy harvester. Therefore, we prove that with vibrations of 0.1g (~1m/s^{2}), it is theoretically possible to harvest up to 30\\muW per gram of mobile mass. This power corresponds to the maximum output power of a resonant energy harvester according to the model of William and Yates. Simulations results are validated by experimental measurements but the issues of parasitic capacitances get a large impact. Therefore, we 'only' managed to harvest 10\\muW per gram of mobile mass, but according to our...
Li, Wenqi; Yu, Lianghong; Peng, Chun; Liang, Xiaoyan
2017-11-01
We proposed a theoretical description and numerical model of signal-spectrum shaping based on conformal profile theory and the three-dimensional coupling wave equations for improving the performance of optical parametric chirped pulse amplification (OPCPA). Using our model, we executed quantitative simulations of signal-spectrum shaping and compared the differences of spatiotemporal amplification characteristics between a shaped signal-spectrum and Gaussian signal-spectrum of an OPCPA based on LiB3O5 near 800 nm. By comparison, we found that the conversion efficiency from pump to signal can be dramatically boosted via signal-spectrum shaping. Meanwhile the amplified-spectrum profile, as well as the Fourier-limited pulse, can be improved significantly. We also found that the spatial spot profiles, for injecting a shaped signal or a Gaussian signal in OPCPA, are nearly the same before the saturation regime and at the maximum conversion efficiency or output energy.
Saturation of THz detection in InGaAs-based HEMTs: a numerical analysis
Energy Technology Data Exchange (ETDEWEB)
Mahi, A. [Centre Universitaire Nour Bachir, B.P. 900, 32000 El Bayadh (Algeria); Palermo, C., E-mail: christophe.palermo@umontpellier.fr [University of Montpellier, IES, UMR 5214, 34000 Montpellier (France); CNRS, IES, UMR 5214, 34000 Montpellier (France); Marinchio, H. [University of Montpellier, IES, UMR 5214, 34000 Montpellier (France); CNRS, IES, UMR 5214, 34000 Montpellier (France); Belgachi, A. [University of Bechar, Bechar 08000 (Algeria); Varani, L. [University of Montpellier, IES, UMR 5214, 34000 Montpellier (France); CNRS, IES, UMR 5214, 34000 Montpellier (France)
2016-11-01
By numerical simulations, we investigate the large-signal photoresponse of InGaAs high electron mobility transistors submitted to THz radiations. The used pseudo-2D hydrodynamic model considers electron density and velocity conservations equations. A third equation is solved, in order to describe average energy conservation or to maintain it constantly equal to its thermal equilibrium value. In both cases, the calculated photoresponse increases with the incoming power density for its smallest values. For the higher values, a saturation of the photoresponse is observed, in agreement with experimental results, only when the energy conservation is accounted for. This allows to relate the limitation of the transistor detection features to electron heating phenomenon.
Directory of Open Access Journals (Sweden)
Emmanuel Quansah
2017-01-01
Full Text Available To understand surface energy exchange processes over the semiarid regions in West Africa, numerical simulations of surface energy and water balances were carried out using a one-dimensional multilayer atmosphere-SOil-VEGetation (SOLVEG model for selected days of the dry and rainy seasons over a savanna grassland ecosystem in Sumbrungu in the Upper East region of Ghana. The measured Bowen ratio was used to partition the residual energy into the observed sensible heat flux (H and latent heat flux (LE in order to investigate the impact of the surface energy closure on model performance. The results showed that the model overall reproduced the diurnal changes in the observed energy fluxes, especially the net radiation (Rn, compared to half-hourly eddy covariance flux measurements, for the study periods. The performance measure in terms of the correlation coefficient (R, centred root mean square error (RMSE, and normalized standard deviation (σ between the simulated H and LE and their corresponding uncorrected observed values ranged between R = 0.63–0.99 and 0.83–0.94, RMSE = 0.88–1.25 and 0.88–1.92, and σ = 0.95–2.23 and 0.13–2.82 for the dry and rainy periods respectively, indicating a moderate to good model performance. The partitioning of H and LE by SOLVEG was generally in agreement with the observations during the dry period but showed clear discrepancies during the rainy period, particularly after rainfall events. Further sensitivity tests over longer simulation periods (e.g., 1 year are required to improve model performance and to investigate seasonal exchanges of surface energy fluxes over the West African Savanna ecosystems in more details.
A frequency-based numerical approach for unsteady radiative transfer in participating media
Energy Technology Data Exchange (ETDEWEB)
Rousse, Daniel R. [Department of Applied Sciences, Universite du Quebec a Chicoutimi, Chicoutimi (Canada)
2008-11-15
The one-dimensional transient radiative transfer problem in the Cartesian coordinate system - an absorbing and scattering medium illuminated by a short laser pulse - is solved by the use of a discrete ordinates-finite volume method. Previous works have shown that the original numerical approach, based in the space-time domain, induces transmitted flux emerging earlier than the minimal time required by the radiation to leave the medium. Therefore, a frequency-based numerical method is formulated, implemented, and validated in this paper. Results for transmittances are accurate, without physically unrealistic behaviors at early time periods. However, the frequency-dependent approach is computationally expensive; it requires approximately five times more computational time than its temporal counterpart. Ongoing research is devoted to the optimization of these CPU requirements. (author)
The Assessment of Oil Pollution in Seribu Islands Based on Remote Sensing and Numerical Models
Putri, Mutiara Rachmat; Setiawan, Agus; Pohlmann, Thomas; Mayer, Bernhard; Gade, Martin
2016-08-01
To improve the information on the state of the Indonesian marine environment that is gained from satellite data, the joint German-Indonesian Pilot Study IndoNACE (Indonesian seas Numerical Assessment of the Coastal Environment) aims at producing oil pollution density maps in Indonesian waters.One of the case study areas is Seribu Islands, located in the northern part of Jakarta Bay in the western Java Sea. Seribu Islands is part of several Marine Protected Areas (MPAs) that are vulnerable to oil pollution, since close to those MPAs a number of offshore oil platforms are located. Based on these conditions, and in order to trace both potential oil pollution sources and potential impacts on the environment, the assessment will be based on in-situ measurements and numerical models. This region is strongly influenced by the monsoon, with ocean currents generally flowing from north towards east during the west (winter) monsoon, and flowing westward during the east (summer) monsoon.
Energy based correlation criteria in the mid-frequency range
Biedermann, J.; Winter, R.; Wandel, M.; Böswald, M.
2017-07-01
Aircraft structures are characterized by their lightweight design. As such, they are prone to vibrations. Numerical models based on the Finite Element Method often show significant deviations when the mid-frequency range is considered, where strong interaction between vibrations and acoustics is present. Model validation based on experimental modal data is often not possible due to the high modal density that aircraft fuselage structures exhibit in this frequency range. Classical correlation criteria like the Modal Assurance Criterion require mode shapes and can therefore not be applied. Other correlation criteria using frequency response data, such as the Frequency Domain Assurance Criterion, are highly sensitive to even small structural modifications and fail to indicated the correlation between test and analysis data in the mid-frequency range. Nevertheless, validated numerical models for the mid- to high-frequency ranges are a prerequisite for acoustic comfort predictions of aircraft cabin. This paper presents a new method for the correlation of response data from test and analysis in the mid-frequency range to support model validation in the mid-frequency range and to enable the usage of finite element models in this frequency range. The method is validated on a stiffened cylindrical shell structure, which represents a scale-model of an aircraft fuselage. The correlation criterion presented here is inspired by Statistical Energy Analysis and is based on kinetic energies integrated over frequency bands and spatially integrated over surface areas of the structure. The objective is to indicate frequency bands where the finite element model needs to be adjusted to better match with experimental observations and to locate the areas where these adjustments should be applied.
Optimization of a Short Faraday Cup for Low-Energy Ions using Numerical Simulations
Bravin, E; Garcia Sosa, A; Welsch, CP
2014-01-01
ISOLDE, the heavy-ion facility at CERN is undergoing a major upgrade with the installation of a superconducting LINAC that will allow post-acceleration of ion beams up to 10 MeV/u. In this framework, customized beam diagnostics are being developed in order to fulfill the design requirements as well as to fit in the compact diagnostic boxes foreseen. The main detector of this system is a compact Faraday cup that will measure beam intensities in the range of 1 pA to 1 nA. In this contribution, simulation results of electrostatic fields and particle tracking are detailed for different Faraday cup prototypes taking into account the energy spectrum and angle of emission of the ion-induced secondary electrons.
Shefer, Olga
2017-11-01
The calculated results of the transmission of visible and infrared radiation by an atmosphere layer involving ensembles of large preferentially oriented crystals and spherical particles are presented. To calculate extinction characteristics, the physical optics method and the Mie theory are applied. Among all atmospheric particles, both the small particles that are commensurable with the wavelength of the incident radiation and the large plates and the columns are distinguished by the most pronounced dependence of the transmission on spectra of radiant energy. The work illustrates features of influence of parameters of the particle size distribution, particle aspect ratios, orientation and particle refractive index, also polarization state of the incident radiation on the transmission. The predominant effect of the plates on the wavelength dependence of the transmission is shown. A separated and cooperative contributes of the large plates and the small volume shape particles to the common transmission by medium are considered.
The Deep Ritz method: A deep learning-based numerical algorithm for solving variational problems
E, Weinan; Yu, Bing
2017-01-01
We propose a deep learning based method, the Deep Ritz Method, for numerically solving variational problems, particularly the ones that arise from partial differential equations. The Deep Ritz method is naturally nonlinear, naturally adaptive and has the potential to work in rather high dimensions. The framework is quite simple and fits well with the stochastic gradient descent method used in deep learning. We illustrate the method on several problems including some eigenvalue problems.
Dadashzadeh, N.; Duzgun, H. S. B.; Yesiloglu-Gultekin, N.
2017-08-01
While advanced numerical techniques in slope stability analysis are successfully used in deterministic studies, they have so far found limited use in probabilistic analyses due to their high computation cost. The first-order reliability method (FORM) is one of the most efficient probabilistic techniques to perform probabilistic stability analysis by considering the associated uncertainties in the analysis parameters. However, it is not possible to directly use FORM in numerical slope stability evaluations as it requires definition of a limit state performance function. In this study, an integrated methodology for probabilistic numerical modeling of rock slope stability is proposed. The methodology is based on response surface method, where FORM is used to develop an explicit performance function from the results of numerical simulations. The implementation of the proposed methodology is performed by considering a large potential rock wedge in Sumela Monastery, Turkey. The accuracy of the developed performance function to truly represent the limit state surface is evaluated by monitoring the slope behavior. The calculated probability of failure is compared with Monte Carlo simulation (MCS) method. The proposed methodology is found to be 72% more efficient than MCS, while the accuracy is decreased with an error of 24%.
Directory of Open Access Journals (Sweden)
Hongru Zhao
2016-11-01
Full Text Available The vertical migration and accumulation of Microcystis is an important process in water blooms, and colony migration is influenced by colony size and wind-wave disturbance. The vertical migration of Microcystis colonies in turbulence can be simulated in a numerical model. In this study, we model such migration by coupling the colony size and hydrodynamics, including the gravity, colony buoyancy, and the viscous drag force of turbulence. The turbulence intensity was represented by the turbulent kinetic energy (KZ; the larger the KZ, the stronger the wind-wave disturbance. The simulated vertical distribution of Microcystis well agreed with the measured values in a laboratory experiment indicating that our model can simulate the vertical distribution of Microcystis under different hydrodynamic conditions. We also found a size-dependent critical turbulent kinetic energy (TKZ, such that if the turbulent kinetic energy of water exceeds the critical value (i.e., KZ > TKZ, the colonies sink under the drag forces of turbulence; conversely, if KZ < TKZ, the colonies can overcome the turbulent mixing and float. The TKZ of each colony was linearly related to colony diameter. The model is crucial for prediction and prevention of water blooms. The simulated threshold turbulent kinetic energy, at which water blooms disappear in Lake Taihu (a large freshwater lake in the Yangtze Delta, Jiangsu Province, China, was 55.5 cm2 s−2.
Everett, R.
1980-07-01
The numerical aspects of the design of low energy consumption houses using passive solar energy collection and high levels of insulation are described. Two housing energy conservation projects were begun, one involving the construction of 177 low energy houses on a cost-effective basis, and the other involving the detailed monitoring of eight highly insulated passive solar houses. Both experimental data and theoretical analysis are presented, and the relative effectiveness of the various design alternatives are discussed.
Subject thesaurus permuted listing: Energy Data Base
Energy Technology Data Exchange (ETDEWEB)
Raridon, M.H. (ed.)
1987-09-01
This permuted listing, an appendix to the Energy Data Base: Subject Thesaurus (DOE/TIC-7000-R6), has been prepared to alleviate the problems of entry to a large multidisciplinary thesaurus containing both single and multi-word descriptors. It is designed to be used in conjunction with the Subject Thesaurus and is not to be used alone. Each descriptor, whether a single word or multi-word entry, has been permuted and alphabetized by each significant word. The complete descriptor is given at each point.
Hydrogen based energy storage for solar energy systems
Energy Technology Data Exchange (ETDEWEB)
Vanhanen, J.; Hagstroem, M.; Lund, P. [Helsinki Univ. of Technology, Otaniemi (Finland). Advanced Energy Systems
1998-10-01
The main technical constraint in solar energy systems which operate around the year is the lack of suitable long-term energy storage. Conventional solutions to overcome the problem of seasonal storage in PV power systems are to use oversized batteries as a seasonal energy storage, or to use a diesel back-up generator. However, affordable lead-acid batteries are not very suitable for seasonal energy storage because of a high self-discharge rate and enhanced deterioration and divergence of the single cells during prolonged periods of low state of charge in times of low irradiation. These disadvantages can be avoided by a back-up system, e.g. a diesel generator, which car supply energy to the loads and charge the battery to the full state of charge to avoid the above mentioned disadvantages. Unfortunately, diesel generators have several disadvantages, e.g. poor starting reliability, frequent need for maintenance and noise
Energy Technology Data Exchange (ETDEWEB)
Yoon, Sang Won [Hanyang University, Seoul (Korea, Republic of)
2017-05-15
This study presents a new design of an electromagnetic energy harvester integrated with a soft magnetic material. The harvester design optimizes the magnetic material characteristics and the size of a rectangular permanent magnet. The design employs a complete magnetic circuit made of (1) a thin-film soft magnetic material that facilitates a flexible but highly (magnetically) permeable beam and (2) an optimally-sized magnet that maximizes the harvester performance. The design is demonstrated to reduce magnetic flux leakage, and thus considerably enhances both magnetic flux density (B) and its change by time (dB/dt), which both influence harvester performance. The improvement in harvester performances strongly depends on critical design parameters, especially, the magnet size and characteristics of magnetic materials, including permeability, stiffness, and thickness. The analyses conclude that recently-introduced nanomaterials (having ultrahigh magnetic permeability) can potentially innovate harvester performances. However, the performance may be degraded without design optimization. Once optimized, the integrated nanomaterials facilitate a significant improvement compared with a conventional design without integrated magnetic materials.
"Physically-based" numerical experiment to determine the dominant hillslope processes during floods?
Gaume, Eric; Esclaffer, Thomas; Dangla, Patrick; Payrastre, Olivier
2016-04-01
To study the dynamics of hillslope responses during flood event, a fully coupled "physically-based" model for the combined numerical simulation of surface runoff and underground flows has been developed. A particular attention has been given to the selection of appropriate numerical schemes for the modelling of both processes and of their coupling. Surprisingly, the most difficult question to solve, from a numerical point of view, was not related to the coupling of two processes with contrasted kinetics such as surface and underground flows, but to the high gradient infiltration fronts appearing in soils, source of numerical diffusion, instabilities and sometimes divergence. The model being elaborated, it has been successfully tested against results of high quality experiments conducted on a laboratory sandy slope in the early eighties, which is still considered as a reference hillslope experimental setting (Abdul & Guilham). The model appeared able to accurately simulate the pore pressure distributions observed in this 1.5 meter deep and wide laboratory hillslope, as well as its outflow hydrograph shapes and the measured respective contributions of direct runoff and groundwater to these outflow hydrographs. Based on this great success, the same model has been used to simulate the response of a theoretical 100-meter wide and 10% sloped hillslope, with a 2 meter deep pervious soil and impervious bedrock. Three rain events have been tested: a 100 millimeter rainfall event over 10 days, over 1 day or over one hour. The simulated responses are hydrologically not realistic and especially the fast component of the response, that is generally observed in the real-world and explains flood events, is almost absent of the simulated response. Thinking a little about the whole problem, the simulation results appears totally logical according to the proposed model. The simulated response, in fact a recession hydrograph, corresponds to a piston flow of a relatively uniformly
Elfwing, Stefan; Uchibe, Eiji; Doya, Kenji
2016-12-01
Free-energy based reinforcement learning (FERL) was proposed for learning in high-dimensional state and action spaces. However, the FERL method does only really work well with binary, or close to binary, state input, where the number of active states is fewer than the number of non-active states. In the FERL method, the value function is approximated by the negative free energy of a restricted Boltzmann machine (RBM). In our earlier study, we demonstrated that the performance and the robustness of the FERL method can be improved by scaling the free energy by a constant that is related to the size of network. In this study, we propose that RBM function approximation can be further improved by approximating the value function by the negative expected energy (EERL), instead of the negative free energy, as well as being able to handle continuous state input. We validate our proposed method by demonstrating that EERL: (1) outperforms FERL, as well as standard neural network and linear function approximation, for three versions of a gridworld task with high-dimensional image state input; (2) achieves new state-of-the-art results in stochastic SZ-Tetris in both model-free and model-based learning settings; and (3) significantly outperforms FERL and standard neural network function approximation for a robot navigation task with raw and noisy RGB images as state input and a large number of actions. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.
Directory of Open Access Journals (Sweden)
Yu.L. Sayenko
2016-05-01
Full Text Available Purpose. Perform numerical analysis of the distribution of the factual contributions of line sources of distortion in the voltage distortion at the point of common coupling, based on the principles of superposition and exclusions. Methodology. Numerical analysis was performed on the results of the simulation steady state operation of power supply system of seven electricity consumers. Results. Mathematical model for determining the factual contribution of line sources of distortion in the voltage distortion at the point of common coupling, based on the principles of superposition and exclusions, are equivalent. To assess the degree of participation of each source of distortion in the voltage distortion at the point of common coupling and distribution of financial compensation to the injured party by all sources of distortion developed a one-dimensional criteria based on the scalar product of vectors. Not accounting group sources of distortion, which belong to the subject of the energy market, to determine their total factual contribution as the residual of the factual contribution between all sources of distortion. Originality. Simulation mode power supply system was carried out in the phase components space, taking into account the distributed characteristics of distortion sources. Practical value. The results of research can be used to develop methods and tools for distributed measurement and analytical systems assessment of the power quality.
Energy Technology Data Exchange (ETDEWEB)
King, D.W.; Griffiths, J.M.; Roderer, N.K.; Wiederkehr, R.R.V.
1982-03-31
An assessment was made of the Energy Data Base (EDB) of the Department of Energy's Technical Information Center (TIC). As the major resource containing access information to the world's energy literature, EDB products and services are used extensively by energy researchers to identify journal articles, technical reports and other items of potential utility in their work. The approach taken to assessing value begins with the measurement of extent of use of the EDB. Apparent value is measured in terms of willingness to pay. Consequential value is measured in terms of effect - for searching, the cost of reading which results; and for reading, the savings which result from the application of the information obtained in reading. Resulting estimates of value reflect value to the searchers, the reader, and the reader's organization or funding source. A survey of the 60,000 scientists and eingineers funded by the DOE shows that annually they read about 7.1 million journal articles and 6.6 million technical reports. A wide range of savings values were reported for one-fourth of all article readings and three-fourths of all report readings. There was an average savings of $590 per reading of all articles; there was an average savings of $1280 for technical reports. The total annual savings attributable to reading by DOE-funded scientists and engineers is estimated to be about $13 billion. An investment of $5.3 billion in the generation of information and about $500 million in processing and using information yields a partial return of about $13 billion. Overall, this partial return on investment is about 2.2 to 1. In determining the value of EDB only those searches and readings directly attributable to it are included in the analysis. The values are $20 million to the searchers, $117 million to the readers and $3.6 billion to DOE.
Kim, Keonwook
2013-01-01
The generic properties of an acoustic signal provide numerous benefits for localization by applying energy-based methods over a deployed wireless sensor network (WSN). However, the signal generated by a stationary target utilizes a significant amount of bandwidth and power in the system without providing further position information. For vehicle localization, this paper proposes a novel proximity velocity vector estimator (PVVE) node architecture in order to capture the energy from a moving v...
Żymełka, Piotr; Nabagło, Daniel; Janda, Tomasz; Madejski, Paweł
2017-12-01
Balanced distribution of air in coal-fired boiler is one of the most important factors in the combustion process and is strongly connected to the overall system efficiency. Reliable and continuous information about combustion airflow and fuel rate is essential for achieving optimal stoichiometric ratio as well as efficient and safe operation of a boiler. Imbalances in air distribution result in reduced boiler efficiency, increased gas pollutant emission and operating problems, such as corrosion, slagging or fouling. Monitoring of air flow trends in boiler is an effective method for further analysis and can help to appoint important dependences and start optimization actions. Accurate real-time monitoring of the air distribution in boiler can bring economical, environmental and operational benefits. The paper presents a novel concept for online monitoring system of air distribution in coal-fired boiler based on real-time numerical calculations. The proposed mathematical model allows for identification of mass flow rates of secondary air to individual burners and to overfire air (OFA) nozzles. Numerical models of air and flue gas system were developed using software for power plant simulation. The correctness of the developed model was verified and validated with the reference measurement values. The presented numerical model for real-time monitoring of air distribution is capable of giving continuous determination of the complete air flows based on available digital communication system (DCS) data.
Herbin, H.; Pujol, O.; Hubert, P.; Petitprez, D.
2017-10-01
The knowledge of aerosol complex refractive indices on wide spectral range with high spectral resolution is important for many research fields and applications. Various combinations of experimental/theoretical/numerical approaches have been employed to determine the optical indices of aerosol particles. However, each approach has its own advantages and limitations that restrict its generalization. This article is first part of a work aimed at proposing a new technique for determining the optical constants of aerosols. Experimentally, the method is based on recording transmittance spectra of an aerosol flow from thermal infrared to UV-visible combined with the size distribution measurements. Herein, we present the theoretical and numerical bases of the algorithm developed to retrieve the imaginary and real parts of refractive indices. This model associates the Mie theory, the single subtractive Kramers-Kronig relations, and the optimal estimation method with an iterative process. In order to quantify the capabilities of the algorithm to retrieve complex refractive indices, inverse calculations are performed from simulated extinction spectra of Quartz particles whose some of optical properties are available in the literature. We have detailed each step of the procedure and performed some comparisons with the most currently employed methods. The impact of experimental accuracy and numerical simulation are investigated in terms of errors, and uncertainties on the retrieved real and imaginary parts of the complex optical index.
Quantity estimation based on numerical cues in the mealworm beetle (Tenebrio molitor
Directory of Open Access Journals (Sweden)
Pau eCarazo
2012-11-01
Full Text Available In this study, we used a biologically relevant experimental procedure to ask whether mealworm beetles (Tenebrio molitor are spontaneously capable of assessing quantities based on numerical cues. Like other insect species, mealworm beetles adjust their reproductive behaviour (i.e. investment in mate guarding according to the perceived risk of sperm competition (i.e. probability that a female will mate with another male. To test whether males have the ability to estimate numerosity based on numerical cues, we staged matings between virgin females and virgin males in which we varied the number of rival males the experimental male had access to immediately preceding mating as a cue to sperm competition risk (from 1 to 4. Rival males were presented sequentially, and we controlled for continuous cues by ensuring that males in all treatments were exposed to the same amount of male-male contact. Males exhibited a marked increase in the time they devoted to mate guarding in response to an increase in the number of different rival males they were exposed to. Since males could not rely on continuous cues we conclude that they kept a running tally of the number of individuals they encountered serially, which meets the requirements of the basic ordinality and cardinality principles of proto-counting. Our results thus offer good evidence of ‘true’ numerosity estimation or quantity estimation and, along with recent studies in honey-bees, suggest that vertebrates and invertebrates share similar core systems of non-verbal numerical representation.
A numerical model for blast injury of human thorax based on digitized visible human.
Li, Xiao-Fang; Kuang, Jiang-Ming; Nie, Si-Bing; Xu, Jing; Zhu, Jin; Liu, Yi-He
2017-12-04
Knowledge of the pressure distribution around human thorax in blast help to understand the injury mechanisms and their assessment. To investigate the transmission mechanism of the pressure on human thorax in blast, a three dimension surface model of human thorax was constructed in this work. To increase the precious of this model, tetrahedron element division method was applied to transfer the rough 3D surface model to hexahedral elements model. Using this model, the high pressure duration was computationally solved using numerical simulation of the hexahedral elements. Simulation results showed that the apex of lungs was subjected to the largest stress in a blast. In order to verify this result, an animal experiment was performed on a dog. The animal experimental results was shown to have a same variation tendency with the calculation results based on our numerical model of human thorax, which made this model reliable for the blast injury research.
Directory of Open Access Journals (Sweden)
Jiangqi Long
2015-01-01
Full Text Available The total weight of Extended-Range Electric Vehicle (E-REV is too heavy, which affects rear-end collision safety. Using numerical simulation, a lightweight method is designed to reduce E-REV body and key parts weight based on rear-end collision failure analysis. To calculate and optimize the performance of vehicle safety, the simulation model of E-REV rear-end collision safety is built by using finite element analysis. Drive battery pack lightweight design method is analyzed and the bending mode and torsional mode of E-REV before and after lightweight are compared to evaluate E-REV rear-end collision safety performance. The simulation results of optimized E-REV safety structure are verified by both numerical simulation and experimental investigation of the entire vehicle crash test.
Applications of Kalman filters based on non-linear functions to numerical weather predictions
Directory of Open Access Journals (Sweden)
G. Galanis
2006-10-01
Full Text Available This paper investigates the use of non-linear functions in classical Kalman filter algorithms on the improvement of regional weather forecasts. The main aim is the implementation of non linear polynomial mappings in a usual linear Kalman filter in order to simulate better non linear problems in numerical weather prediction. In addition, the optimal order of the polynomials applied for such a filter is identified. This work is based on observations and corresponding numerical weather predictions of two meteorological parameters characterized by essential differences in their evolution in time, namely, air temperature and wind speed. It is shown that in both cases, a polynomial of low order is adequate for eliminating any systematic error, while higher order functions lead to instabilities in the filtered results having, at the same time, trivial contribution to the sensitivity of the filter. It is further demonstrated that the filter is independent of the time period and the geographic location of application.
Directory of Open Access Journals (Sweden)
Dina V. Lazareva
2015-06-01
Full Text Available A new mathematical model of asymmetric support structure frame type is built on the basis of numerical-analytical boundary elements method (BEM. To describe the design scheme used is the graph theory. Building the model taken into account is the effect of frame members restrained torsion, which presence is due to the fact that these elements are thin-walled. The built model represents a real object as a two-axle semi-trailer platform. To implement the BEM algorithm obtained are analytical expressions of the fundamental functions and vector load components. The effected calculations are based on the semi-trailer two different models, using finite elements and boundary elements methods. The analysis showed that the error between the results obtained on the basis of two numerical methods and experimental data is about 4%, that indicates the adequacy of the proposed mathematical model.
Numerical Simulation of Sloshing in 2D Rectangular Tanks Based on the Prediction of Free Surface
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Haitao Zhang
2014-01-01
Full Text Available A finite difference method for analyzing 2D nonlinear sloshing waves in a tank has been developed based on the potential flow theory. After σ-transformation, the free surface is predicted by the kinematic condition, and nonlinear terms are approximated; the governing equation and boundary conditions are discretized to linear equations in the iterative process of time. Simulations of standing waves and sloshing in horizontally excited tanks are presented. The results are compared with analytical and numerical solutions in other literatures, which demonstrate the effectiveness and accuracy of this numerical method. The beating phenomenon of sloshing in the tank with different aspect ratios is studied. The relationship between sloshing force and aspect ratio under the same external excitation is also discussed.
Amadei, A; Apol, MEF; DiNola, A; Berendsen, HJC
1996-01-01
A new theory is presented for calculating the Helmholtz free energy based on the potential energy distribution function. The usual expressions of free energy, internal energy and entropy involving the partition function are rephrased in terms of the potential energy distribution function, which must
The Three-Dimensional Parallel Numerical Code on the Base of Mixed Lagrange-Eulerian Approach
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Shushkеvich Tatyana Sеrgееvna
2015-10-01
Full Text Available In this paper the parallel numerical code developed for integration of gas-dynamics equations in the three-dimensional case on the base of mixed Lagrange-Eulerian approach was described. The method of paralleling, allowing effective use of computation properties of computer cluster with multiprocessor nodes, was shown. The results of performance testing, which shown significant growth of computations comparing to serial version of the software was shown. For parallelization of numerical code, combination of OpenMP and MPI technologies was used: on each node of computer cluster runs multithread calculation process. Methodology of data parallelism was implemented (in other words, single instruction—multiple data. For dividing data between calculation processes, partitioning of computational domain along one axis was used. OpenMP technology leads to acceleration of calculations relative to number of processor cores with coefficient 0.93. MPI technology leads to acceleration of calculations relative to number of computation cluster nodes with coefficient 0.9. Combination of OpenMP+MPI leads to acceleration of calculations with coefficient 0.98. Testing of computational performance was made on computer cluster with these characteristics: Intel(R Core(TM 2 CPU E 8400, 2 Gb RAM, communication media—Gigabit Ethernet 1000Base-T. The results have shown that the numerical code was effectivly parallelized: with using combination MPI+OpenMP on two-node cluster computational performance growth to approximately in 1.96 times (computational grid size depended; on four nodes—approximately in 3.87 times; on eight nodes—approximately in 7.86 times. Total computational performance has grown on the average by 10–15% instead of results obtained by using only MPI. The developed computer program can be used for numerical solving of the three-dimensional gas-dynamics equations with detailed grids with computational clusters of multiprocessor nodes.
Energy Technology Data Exchange (ETDEWEB)
Xu, W.; Dycus, J.H.; Sang, X.; LeBeau, J.M., E-mail: jmlebeau@ncsu.edu
2016-05-15
Here we report a numerical approach to model a four quadrant energy dispersive X-ray spectrometer in the transmission electron microscope. The model includes detector geometries, specimen position and absorption, shadowing by the holder, and filtering by the Be carrier. We show that this comprehensive model accurately predicts absolute counts and intensity ratios as a function of specimen tilt and position. We directly compare the model to experimental results acquired with a FEI Super-X EDS four quadrant detector. The contribution from each detector to the sum is investigated. The program and source code can be downloaded from (https://github.com/subangstrom/superAngle). - Highlights: • A novel numeric model is developed to predict the effective detector collection angle for multi-detector EDS in the transmission electron microscope. • The precise geometry of specimen holder is incorporated to determine the influence of holder shadowing • The role of X-ray filtering by the Be specimen carrier is investigated. • Predicted counts and intensity ratios are directly compared to experiment as a function of tilt and are shown to be in excellent agreement • The detector intensity sum effectively reduces errors compared to the individual detector signals.
Energy harvesting from a DE-based dynamic vibro-impact system
Yurchenko, D.; Val, D. V.; Lai, Z. H.; Gu, G.; Thomson, G.
2017-10-01
Dielectric elastomer (DE) generators may be used in harvesting energy from ambient vibrations. Based on existing research on the mechanical properties of a circular DE membrane, a DE-based dynamic vibro-impact system is proposed in this paper to convert vibrational energy into electrical one. The dimensional, electrical and dynamic parameters of the DE membrane are analysed and then used to numerically estimate the output voltage of the proposed system. The system output performances under harmonic excitation are further discussed. At last, the comparison study has been conducted with an electromagnetic energy harvesting system, served as a ‘shaking’ flashlight.
Lin, Chao; Shen, Xueju; Wang, Zhisong; Zhao, Cheng
2014-06-20
We demonstrate a novel optical asymmetric cryptosystem based on the principle of elliptical polarized light linear truncation and a numerical reconstruction technique. The device of an array of linear polarizers is introduced to achieve linear truncation on the spatially resolved elliptical polarization distribution during image encryption. This encoding process can be characterized as confusion-based optical cryptography that involves no Fourier lens and diffusion operation. Based on the Jones matrix formalism, the intensity transmittance for this truncation is deduced to perform elliptical polarized light reconstruction based on two intensity measurements. Use of a quick response code makes the proposed cryptosystem practical, with versatile key sensitivity and fault tolerance. Both simulation and preliminary experimental results that support theoretical analysis are presented. An analysis of the resistance of the proposed method on a known public key attack is also provided.
Extremum-Seeking Control and Applications A Numerical Optimization-Based Approach
Zhang, Chunlei
2012-01-01
Extremum seeking control tracks a varying maximum or minimum in a performance function such as a cost. It attempts to determine the optimal performance of a control system as it operates, thereby reducing downtime and the need for system analysis. Extremum Seeking Control and Applications is divided into two parts. In the first, the authors review existing analog optimization based extremum seeking control including gradient, perturbation and sliding mode based control designs. They then propose a novel numerical optimization based extremum seeking control based on optimization algorithms and state regulation. This control design is developed for simple linear time-invariant systems and then extended for a class of feedback linearizable nonlinear systems. The two main optimization algorithms – line search and trust region methods – are analyzed for robustness. Finite-time and asymptotic state regulators are put forward for linear and nonlinear systems respectively. Further design flexibility is achieved u...
Wang, Ying; Krafczyk, Manfred; Geier, Martin; Schönherr, Martin
2014-05-01
The quantification of soil evaporation and of soil water content dynamics near the soil surface are critical in the physics of land-surface processes on many scales and are dominated by multi-component and multi-phase mass and energy fluxes between the ground and the atmosphere. Although it is widely recognized that both liquid and gaseous water movement are fundamental factors in the quantification of soil heat flux and surface evaporation, their computation has only started to be taken into account using simplified macroscopic models. As the flow field over the soil can be safely considered as turbulent, it would be natural to study the detailed transient flow dynamics by means of Large Eddy Simulation (LES [1]) where the three-dimensional flow field is resolved down to the laminar sub-layer. Yet this requires very fine resolved meshes allowing a grid resolution of at least one order of magnitude below the typical grain diameter of the soil under consideration. In order to gain reliable turbulence statistics, up to several hundred eddy turnover times have to be simulated which adds up to several seconds of real time. Yet, the time scale of the receding saturated water front dynamics in the soil is on the order of hours. Thus we are faced with the task of solving a transient turbulent flow problem including the advection-diffusion of water vapour over the soil-atmospheric interface represented by a realistic tomographic reconstruction of a real porous medium taken from laboratory probes. Our flow solver is based on the Lattice Boltzmann method (LBM) [2] which has been extended by a Cumulant approach similar to the one described in [3,4] to minimize the spurious coupling between the degrees of freedom in previous LBM approaches and can be used as an implicit LES turbulence model due to its low numerical dissipation and increased stability at high Reynolds numbers. The kernel has been integrated into the research code Virtualfluids [5] and delivers up to 30% of the
2012-12-25
Phytoplankton Blooms on Ocean-Atmosphere Thermal Energy Exchange: Evidence from a Two-Way Coupled Numerical Modeling System 5a. CONTRACT NUMBER... phytoplankton stocks in a coastal embayment may impact thermal energy exchange processes. Monterey Bay simulations parameterizing solar shortwave transparency...in the surface ocean as an invariant oligotrophic oceanic water type estimate consistently colder sea surface temperature (SST) than simulations
Numerical design of FSHL-based approximate cloaks with arbitrary shapes
Wang, Qi; Hou, Yanren; Li, Jingzhi
2017-03-01
This paper considers numerical design of finite sound-hard lining (FSHL)-based approximate cloaks with arbitrary shapes. Regarding the complexity of the shape, two new approaches are proposed to design the transformation map from the virtual space to the physical space via transformation optics. For star-shaped geometry, we propose an explicit global transformation map which can be easily differentiated and inverted. For more general shapes, an Initialize-Untangle-Extend (IUE) approach is initiated to build locally piecewise differentiable deformations, which can be locally inverted with the help of an approximate triangulation. With the locally piecewise-constructed transformation, the parameters of acoustic scattering models in physical space can be determined in both approaches based on the transformation invariance of the Helmholtz system. Then the cloaking effects for an arbitrary shape FSHL-based cloak can be realized following Li et al. (2012) [5]. Extensive numerical experiments are presented to illustrate both the effectiveness of cloak design and the efficiency of the proposed FSHL-based cloaks with arbitrary shapes.
Directory of Open Access Journals (Sweden)
Haixiong Yu
2014-01-01
Full Text Available We apply a lumped mass finite element to approximate Dirichlet problems for nonsmooth elliptic equations. It is proved that the lumped mass FEM approximation error in energy norm is the same as that of standard piecewise linear finite element approximation. Under the quasi-uniform mesh condition and the maximum angle condition, we show that the operator in the finite element problem is diagonally isotone and off-diagonally antitone. Therefore, some monotone convergent algorithms can be used. As an example, we prove that the nonsmooth Newton-like algorithm is convergent monotonically if Gauss-Seidel iteration is used to solve the Newton's equations iteratively. Some numerical experiments are presented.
Gao, Kai
2015-06-05
The development of reliable methods for upscaling fine-scale models of elastic media has long been an important topic for rock physics and applied seismology. Several effective medium theories have been developed to provide elastic parameters for materials such as finely layered media or randomly oriented or aligned fractures. In such cases, the analytic solutions for upscaled properties can be used for accurate prediction of wave propagation. However, such theories cannot be applied directly to homogenize elastic media with more complex, arbitrary spatial heterogeneity. Therefore, we have proposed a numerical homogenization algorithm based on multiscale finite-element methods for simulating elastic wave propagation in heterogeneous, anisotropic elastic media. Specifically, our method used multiscale basis functions obtained from a local linear elasticity problem with appropriately defined boundary conditions. Homogenized, effective medium parameters were then computed using these basis functions, and the approach applied a numerical discretization that was similar to the rotated staggered-grid finite-difference scheme. Comparisons of the results from our method and from conventional, analytical approaches for finely layered media showed that the homogenization reliably estimated elastic parameters for this simple geometry. Additional tests examined anisotropic models with arbitrary spatial heterogeneity in which the average size of the heterogeneities ranged from several centimeters to several meters, and the ratio between the dominant wavelength and the average size of the arbitrary heterogeneities ranged from 10 to 100. Comparisons to finite-difference simulations proved that the numerical homogenization was equally accurate for these complex cases.
Li, Xun; Hu, Sanqing; Li, Lihua; Zhu, Shanan
2013-01-01
Magnetoacoustic tomography with magnetic induction (MAT-MI) is a noninvasive imaging modality for generating electrical conductivity images of biological tissues with high spatial resolution. In this paper, we create a numerical model, including a permanent magnet, a coil, and a two-layer coaxial cylinder with anisotropic electrical conductivities, for the MAT-MI forward problem. We analyze the MAT-MI sources in two cases, on a thin conductive boundary layer and in a homogeneous medium, and then develop a feasible numerical approach to solve the MAT-MI sound source densities in the anisotropic conductive model based on finite element analysis of electromagnetic field. Using the numerical finite element method, we then investigate the magnetoacoustic effect of anisotropic conductivity under the inhomogeneous static magnetic field and inhomogeneous magnetic field, quantitatively compute the boundary source densities in the conductive model, and calculate the sound pressure. The anisotropic conductivity contributes to the distribution of the eddy current density, Lorentz force density, and acoustic signal. The proposed models and approaches provide a more realistic simulation environment for MAT-MI.
Algal-Based Renewable Energy for Nevada
Energy Technology Data Exchange (ETDEWEB)
Fritsen, Christian [Desert Research Institute, Las Vegas, NV (United States)
2017-03-31
To help in the overall evaluation of the potential for growing algal biomass in high productivity systems, we conducted a study that evaluated water from geothermal sources and cultivated mixed consortia from hot springs in Nevada, we evaluated their growth at moderately high varying temperatures and then evaluated potential manipulations that could possibly increase their biomass and oleaginous production. Studies were conducted at scales ranging from the laboratory benchtop to raceways in field settings. Mixed consortia were readily grown at all scales and growth could be maintained in Nevada year round. Moderate productivities were attained even during the shoulder seasons- where temperature control was maintained by hot water and seasonally cold temperatures when there was still plentiful solar radiation. The results enhance the prospects for economic feasibility of developing algal based industries in areas with geothermal energy or even other large alternative sources of heat that are not being used for other purposes. The public may benefit from such development as a means for economic development as well as development of industries for alternative energy and products that do not rely on fossil fuels.
Dielectric Sensors Based on Electromagnetic Energy Tunneling
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Omar Siddiqui
2015-03-01
Full Text Available We show that metallic wires embedded in narrow waveguide bends and channels demonstrate resonance behavior at specific frequencies. The electromagnetic energy at these resonances tunnels through the narrow waveguide channels with almost no propagation losses. Under the tunneling behavior, high-intensity electromagnetic fields are produced in the vicinity of the metallic wires. These intense field resonances can be exploited to build highly sensitive dielectric sensors. The sensor operation is explained with the help of full-wave simulations. A practical setup consisting of a 3D waveguide bend is presented to experimentally observe the tunneling phenomenon. The tunneling frequency is predicted by determining the input impedance minima through a variational formula based on the Green function of a probe-excited parallel plate waveguide.
3D Printed Graphene Based Energy Storage Devices
Foster, Christopher W.; Down, Michael P.; Zhang, Yan; Ji, Xiaobo; Rowley-Neale, Samuel J.; Smith, Graham C.; Kelly, Peter J.; Banks, Craig E.
2017-03-01
3D printing technology provides a unique platform for rapid prototyping of numerous applications due to its ability to produce low cost 3D printed platforms. Herein, a graphene-based polylactic acid filament (graphene/PLA) has been 3D printed to fabricate a range of 3D disc electrode (3DE) configurations using a conventional RepRap fused deposition moulding (FDM) 3D printer, which requires no further modification/ex-situ curing step. To provide proof-of-concept, these 3D printed electrode architectures are characterised both electrochemically and physicochemically and are advantageously applied as freestanding anodes within Li-ion batteries and as solid-state supercapacitors. These freestanding anodes neglect the requirement for a current collector, thus offering a simplistic and cheaper alternative to traditional Li-ion based setups. Additionally, the ability of these devices’ to electrochemically produce hydrogen via the hydrogen evolution reaction (HER) as an alternative to currently utilised platinum based electrodes (with in electrolysers) is also performed. The 3DE demonstrates an unexpectedly high catalytic activity towards the HER (-0.46 V vs. SCE) upon the 1000th cycle, such potential is the closest observed to the desired value of platinum at (-0.25 V vs. SCE). We subsequently suggest that 3D printing of graphene-based conductive filaments allows for the simple fabrication of energy storage devices with bespoke and conceptual designs to be realised.
Randolph, J. B.; Saar, M. O.
2009-12-01
Carbon dioxide (CO2) sequestration in deep saline aquifers and exhausted oil fields has been widely considered as a means for reducing CO2 emissions to the atmosphere as a counter-measure to global warming. However, rather than treating CO2 as a waste fluid in need of permanent disposal, it could additionally be used as a working fluid in geothermal energy capture as its thermodynamic properties suggest it transfers heat more efficiently than water. Therefore, utilizing CO2 may permit more widespread implementation of geothermal power systems. Here, we present numerical modeling results of coupled CO2 injection into a brine and heat transfer in geothermal reservoirs under conditions relevant for both CO2 sequestration and geothermal electricity generation. In particular, we examine subsurface flow and heating of the sequestered CO2, cooling of the geothermal reservoir, and changes in pore-fluid pressures under a variety of generalized CO2 injection and production scenarios and reservoir characteristics. While additional research is required, modeling results at present suggest that geologic reservoirs with CO2 as the heat mining fluid would be viable geothermal energy sources for electric power production for decades, potentially even in regions with relatively low geothermal temperatures and heat flow rates.
Galatà, A.; Mascali, D.; Neri, L.; Torrisi, G.; Celona, L.
2016-02-01
A Charge Breeder (CB) is a crucial device of an ISOL facility, allowing post-acceleration of radioactive ions: it accepts an incoming 1+ beam, then multiplying its charge with a highly charged q+ beam as an output. The overall performances of the facility (intensity and attainable final energy) critically depend on the charge breeder optimization. Experimental results collected along the years confirm that the breeding process is still not fully understood and room for improvements still exists: a new numerical approach has been therefore developed and applied to the description of a 85Rb1+ beam capture by the plasma of the 14.5 GHz PHOENIX ECR-based CB, installed at the Laboratoire de Physique Subatomique et de Cosmologie (LPSC), and adopted for the Selective Production of Exotic Species project under construction at Laboratori Nazionali di Legnaro. The results of the numerical simulations, obtained implementing a plasma-target model of increasing accuracy and different values for the plasma potential, will be described along the paper: results very well agree with the theoretical predictions and with the experimental results obtained on the LPSC test bench.
Energy Technology Data Exchange (ETDEWEB)
Galatà, A., E-mail: alessio.galata@lnl.infn.it [INFN–Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); Mascali, D.; Neri, L.; Torrisi, G.; Celona, L. [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy)
2016-02-15
A Charge Breeder (CB) is a crucial device of an ISOL facility, allowing post-acceleration of radioactive ions: it accepts an incoming 1+ beam, then multiplying its charge with a highly charged q+ beam as an output. The overall performances of the facility (intensity and attainable final energy) critically depend on the charge breeder optimization. Experimental results collected along the years confirm that the breeding process is still not fully understood and room for improvements still exists: a new numerical approach has been therefore developed and applied to the description of a {sup 85}Rb{sup 1+} beam capture by the plasma of the 14.5 GHz PHOENIX ECR-based CB, installed at the Laboratoire de Physique Subatomique et de Cosmologie (LPSC), and adopted for the Selective Production of Exotic Species project under construction at Laboratori Nazionali di Legnaro. The results of the numerical simulations, obtained implementing a plasma-target model of increasing accuracy and different values for the plasma potential, will be described along the paper: results very well agree with the theoretical predictions and with the experimental results obtained on the LPSC test bench.
Numerical methods and inversion algorithms in reservoir simulation based on front tracking
Energy Technology Data Exchange (ETDEWEB)
Haugse, Vidar
1999-04-01
This thesis uses front tracking to analyse laboratory experiments on multiphase flow in porous media. New methods for parameter estimation for two- and three-phase relative permeability experiments have been developed. Up scaling of heterogeneous and stochastic porous media is analysed. Numerical methods based on front tracking is developed and analysed. Such methods are efficient for problems involving steep changes in the physical quantities. Multi-dimensional problems are solved by combining front tracking with dimensional splitting. A method for adaptive grid refinement is developed.
Numerical focusing methods for full field OCT: a comparison based on a common signal model.
Kumar, Abhishek; Drexler, Wolfgang; Leitgeb, Rainer A
2014-06-30
In this paper a theoretical model of the full field swept source (FF SS) OCT signal is presented based on the angular spectrum wave propagation approach which accounts for the defocus error with imaging depth. It is shown that using the same theoretical model of the signal, numerical defocus correction methods based on a simple forward model (FM) and inverse scattering (IS), the latter being similar to interferometric synthetic aperture microscopy (ISAM), can be derived. Both FM and IS are compared quantitatively with sub-aperture based digital adaptive optics (DAO). FM has the least numerical complexity, and is the fastest in terms of computational speed among the three. SNR improvement of more than 10 dB is shown for all the three methods over a sample depth of 1.5 mm. For a sample with non-uniform refractive index with depth, FM and IS both improved the depth of focus (DOF) by a factor of 7x for an imaging NA of 0.1. DAO performs the best in case of non-uniform refractive index with respect to DOF improvement by 11x.
Directory of Open Access Journals (Sweden)
Rašković Predrag O.
2008-01-01
Full Text Available This paper presents an on-going research project that aims to identify possibilities for wider use of evaporative cooling in process industry, especially the use of evaporative fluid cooler units. Experimental study is performed on small scale evaporative fluid cooler, while the correlation based model has been carried out to explore the detailed heat and mass transfer processes inside this unit. Numerical integration of mathematical model is executed by new approach, based on differential, collocation Simpson method. Proposed models have been verified by comparing the computed results with those obtained by the experimental measurements. The results of research will enable the creation of more comprehensive simulation software, with wider range of operating and construction parameters.
A Novel FEM-Based Numerical Solver for Interactive Catheter Simulation in Virtual Catheterization
Directory of Open Access Journals (Sweden)
Shun Li
2011-01-01
Full Text Available Virtual reality-based simulators are very helpful for trainees to acquire the skills of manipulating catheters and guidewires during the vascular interventional surgeries. In the development of such a simulator, however, it is a great challenge to realistically model and simulate deformable catheters and guidewires in an interactive manner. We propose a novel method to simulate the motion of catheters or guidewires and their interactions with patients' vascular system. Our method is based on the principle of minimal total potential energy. We formulate the total potential energy in the vascular interventional circumstance by summing up the elastic energy deriving from the bending of the catheters or guidewires, the potential energy due to the deformation of vessel walls, and the work by the external forces. We propose a novel FEM-based approach to simulate the deformation of catheters and guidewires. The motion of catheters or the guidewires and their responses to every input from the interventionalist can be calculated globally. Experiments have been conducted to validate the feasibility of the proposed method, and the results demonstrate that our method can realistically simulate the complex behaviors of catheters and guidewires in an interactive manner.
Directory of Open Access Journals (Sweden)
Jiwei Song
2017-05-01
Full Text Available The past decade has seen increased focus on nanoparticle (NP based drilling fluid to promote wellbore stability in shales. With the plugging of NP into shale pores, the fluid pressure transmission can be retarded and wellbore stability can be improved. For better understanding of the interaction between shale and NP based drilling fluid based on previous pressure transmission tests (PTTs on Atoka shale samples, this paper reports the numerical simulation findings of wellbore stability in the presence of NP based drilling fluid, using the 2D fluid-solid coupling model in FLAC3D™ software. The results of previous PTT are discussed first, where the steps of numerical simulation, the simulation on pore fluid pressure transmission, the distribution of stress and the deformation of surrounding rock are presented. The mechanisms of NP in reducing permeability and stabilizing shale are also discussed. Results showed that fluid filtrate from water-based drilling fluid had a strong tendency to invade the shale matrix and increase the likelihood of wellbore instability in shales. However, the pore fluid pressure near wellbore areas could be minimized by plugging silica NP into the nanoscale pores of shales, which is consistent with previous PTT. Pore pressure transmission boundaries could also be restricted with silica NP. Furthermore, the stress differential and shear stress of surrounding rock near the wellbore was reduced in the presence of NP. The plastic yield zone was minimized to improve wellbore stability. The plugging mechanism of NP may be attributed to the electrostatic and electrodynamic interactions between NP and shale surfaces that are governed by Derjaguin-Landau-Verwey-Overbeek (DLVO forces, which allowed NP to approach shale surfaces and adhere to them. We also found that discretization of the simulation model was beneficial in distinguishing the yield zone distribution of the surrounding rock in shales. The combination of PTT and the 2
Energy-based and biomimetic robotics
Folkertsma, Gerrit Adriaan
2017-01-01
All physical systems interact by exchanging power, or energy. This energy can be explicitly taken into account when designing robotic systems, in dynamic models of systems and controllers, leading to more insight in energy-related effects. In this thesis, a biomimetic cheetah robot is developed, by
Tomography based numerical simulation of the demagnetizing field in soft magnetic composites
Arzbacher, S.; Amann, P.; Weidenfeller, B.; Loerting, T.; Ostermann, A.; Petrasch, J.
2015-04-01
The magneto-static behaviour of soft magnetic composites (SMCs) is investigated using tomography based direct numerical simulation. The microgeometry crucially affects the magnetic properties of the composite since a geometry dependent demagnetizing field is established inside the composite, which lowers the magnetic permeability. We determine the magnetic field information inside the SMC using direct numerical simulation of the magnetic field based on high resolution micro-computed tomography data of the SMC's microstructure as well as artificially generated data made of statistically homogeneous systems of identical fully penetrable spheres and prolate spheroids. Quasi-static electromagnetic behaviour and linear material response are assumed. The 3D magnetostatic Maxwell equations are solved using Whitney finite elements. Simulations show that clustering and percolation behaviour determine the demagnetizing factor of SMCs rather than the particle shape. The demagnetizing factor correlates with the slope of a 2-point probability function at its origin, which is related to the specific surface area of the SMC. Comparison with experimental results indicates that the relatively low permeability of SMCs cannot be explained by demagnetizing effects alone and suggests that the permeability of SMC particles has to be orders of magnitude smaller than the bulk permeability of the particle material.
Tomography based numerical simulation of the demagnetizing field in soft magnetic composites
Energy Technology Data Exchange (ETDEWEB)
Arzbacher, S.; Petrasch, J., E-mail: joerg.petrasch@fhv.at [illwerke vkw Professorship for Energy Efficiency, Vorarlberg University of Applied Sciences, Hochschulstraße 1, 6850 Dornbirn (Austria); Amann, P. [Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm (Sweden); Weidenfeller, B. [Institute of Electrochemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 6, 38678 Clausthal-Zellerfeld (Germany); Loerting, T. [Institute of Physical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck (Austria); Ostermann, A. [Department of Mathematics, University of Innsbruck, Technikerstraße 13, 6020 Innsbruck (Austria)
2015-04-28
The magneto-static behaviour of soft magnetic composites (SMCs) is investigated using tomography based direct numerical simulation. The microgeometry crucially affects the magnetic properties of the composite since a geometry dependent demagnetizing field is established inside the composite, which lowers the magnetic permeability. We determine the magnetic field information inside the SMC using direct numerical simulation of the magnetic field based on high resolution micro-computed tomography data of the SMC's microstructure as well as artificially generated data made of statistically homogeneous systems of identical fully penetrable spheres and prolate spheroids. Quasi-static electromagnetic behaviour and linear material response are assumed. The 3D magnetostatic Maxwell equations are solved using Whitney finite elements. Simulations show that clustering and percolation behaviour determine the demagnetizing factor of SMCs rather than the particle shape. The demagnetizing factor correlates with the slope of a 2-point probability function at its origin, which is related to the specific surface area of the SMC. Comparison with experimental results indicates that the relatively low permeability of SMCs cannot be explained by demagnetizing effects alone and suggests that the permeability of SMC particles has to be orders of magnitude smaller than the bulk permeability of the particle material.
A Numerical Study of Aerodynamic Performance and Noise of a Bionic Airfoil Based on Owl Wing
Directory of Open Access Journals (Sweden)
Xiaomin Liu
2014-08-01
Full Text Available Noise reduction and efficiency enhancement are the two important directions in the development of the multiblade centrifugal fan. In this study, we attempt to develop a bionic airfoil based on the owl wing and investigate its aerodynamic performance and noise-reduction mechanism at the relatively low Reynolds number. Firstly, according to the geometric characteristics of the owl wing, a bionic airfoil is constructed as the object of study at Reynolds number of 12,300. Secondly, the large eddy simulation (LES with the Smagorinsky model is adopted to numerically simulate the unsteady flow fields around the bionic airfoil and the standard NACA0006 airfoil. And then, the acoustic sources are extracted from the unsteady flow field data, and the Ffowcs Williams-Hawkings (FW-H equation based on Lighthill's acoustic theory is solved to predict the propagation of these acoustic sources. The numerical results show that the lift-to-drag ratio of bionic airfoil is higher than that of the traditional NACA 0006 airfoil because of its deeply concave lower surface geometry. Finally, the sound field of the bionic airfoil is analyzed in detail. The distribution of the A-weighted sound pressure levels, the scaled directivity of the sound, and the distribution of dP/dt on the airfoil surface are provided so that the characteristics of the acoustic sources could be revealed.
Numerical Analysis of Flattened Brazilian Disc Test Based on the Cusp Catastrophe Theory
Directory of Open Access Journals (Sweden)
Min Wang
2016-01-01
Full Text Available The Brazilian disc test is a simple and useful technique to determine the tensile strength of rock materials. By using FLAC3D, 63 numerical simulations in total were performed when flattened Brazilian disc coefficient and Poisson’s ratio were different. Based on Griffith theory, the corresponding FISH language was compiled to record the Griffith equivalent stress. Through analysis of numerical simulation results, it is indicated that fracture plane was not the plane going through center of the Brazilian disc, which was in good agreement with the references. In addition, the flattened Brazilian disc coefficients had greater influence on tensile strength than Poisson’s ratio. Based on cusp catastrophe theory, the flattened Brazilian disc coefficient should not exceed 0.035 for the flattened Brazilian disc tests. Consequently, a tensile strength empirical formula considering flattened Brazilian disc coefficient by utilizing the flattened Brazilian disc test was established, which was σt=0.9993 exp (-11.65ε2p/πDt, ε≤0.035.
Directory of Open Access Journals (Sweden)
Popov V.V
2016-01-01
Full Text Available In this paper, a numerical study of the formation of nitrogen oxides in the combustion chamber based on the model created by Mitchellom and Terbellom. The distribution of furnace temperature and the concentration of nitrogen oxides, as well as a comparison of numerical results with the data of field experiment.
Triangular Energy-Saving Cache-Based Routing Protocol by Energy Sieving
Chiu-Ching Tuan; Yi-Chao Wu
2012-01-01
In wireless ad hoc networks, designing an energy-efficient routing protocol is a major issue since nodes are energy limited. To address energy issue, we proposed a triangular energy-saving cached-based routing protocol by energy sieving (TESCES). TESCES offered a grid leader election by energy sieving (GLEES), a cache-based grid leader maintenance (CGLM), and a triangular energy-saving routing discovery (TESRD). In GLEES, only few nodes join in grid leader election to be elected as a grid lea...
Direct numerical simulation of a fluid flow in core samples based on quasi-hydrodynamic equations
Balashov, V. A.; Savenkov, E. B.; Kuleshov, A. A.
2016-12-01
Direct numerical modeling techniques for the evaluation of a macroscopic permeability coefficient of samples of naturally occurring geological media using their micro-computer tomography (micro-CT) images is considered. The basic mathematical model of a flow is based on quasi-hydrodynamic (QHD) equations for viscous heat-conducting compressible gas flows. The evaluation of a permeability coefficient of artificial and real porous media is discussed. Free available micro-CT images are used. Results of computations for artificial porous media are compared with the analytic ones, for real porous media — with the results obtained by the Lattice Boltzmann method and results obtained by other researchers. It is shown that the approach based on QHD equations is highly competitive with other approaches.
Energy Technology Data Exchange (ETDEWEB)
Fansi, Joseph, E-mail: jfansi@doct.ulg.ac.be [University of Liège, Departement ArGEnCo, Division MS2F, Chemin des Chevreuils 1, Liège 4000 (Belgium); Arts et Métiers ParisTech, LEM3, UMR CNRS 7239, 4 rue A. Fresnel, 57078 Metz cedex 03 (France); ArcelorMittal R and D Global Maizières S.A., voie Romaine, Maizières-Lès-Metz 57238 (France); Balan, Tudor [Arts et Métiers ParisTech, LEM3, UMR CNRS 7239, 4 rue A. Fresnel, 57078 Metz cedex 03 (France); Lemoine, Xavier [Arts et Métiers ParisTech, LEM3, UMR CNRS 7239, 4 rue A. Fresnel, 57078 Metz cedex 03 (France); ArcelorMittal R and D Global Maizières S.A., voie Romaine, Maizières-Lès-Metz 57238 (France); Maire, Eric; Landron, Caroline [INSA de Lyon, MATEIS CNRS UMR5510, 7 Avenue Jean Capelle, Villeurbanne 69621 (France); Bouaziz, Olivier [ArcelorMittal R and D Global Maizières S.A., voie Romaine, Maizières-Lès-Metz 57238 (France); Ecole des Mines de Paris, Centre des Matériaux, CNRS UMR 7633, BP 87, Evry Cedex 91003 (France); Ben Bettaieb, Mohamed [Ensicaen, 6 Boulevard du Maréchal Juin, 14050 CAEN Cedex 4 (France); Marie Habraken, Anne [University of Liège, Departement ArGEnCo, Division MS2F, Chemin des Chevreuils 1, Liège 4000 (Belgium)
2013-05-01
This numerical investigation of an advanced Gurson–Tvergaard–Needleman (GTN) model is an extension of the original work of Ben Bettaiebet al. (2011 [18]). The model has been implemented as a user-defined material model subroutine (VUMAT) in the Abaqus/explicit FE code. The current damage model extends the previous version by integrating the three damage mechanisms: nucleation, growth and coalescence of voids. Physically based void nucleation and growth laws are considered, including an effect of the kinematic hardening. These new contributions are based and validated on experimental results provided by high-resolution X-ray absorption tomography measurements. The current damage model is applied to predict the damage evolution and the stress state in a tensile notched specimen experiment.
Directory of Open Access Journals (Sweden)
Zhen Liu
2016-09-01
Full Text Available Self-starting performance is a key factor in the evaluation of a Darrieus straight-bladed vertical axis turbine. Most traditional studies have analyzed the turbine’s self-starting capability using the experimental and numerical data of the forced rotation. A 2D numerical model based on the computational fluid dynamics (CFD software ANSYS-Fluent was developed to simulate the self-starting process of the rotor at constant incident water-flow velocities. The vertical-axis turbine (VAT rotor is driven directly by the resultant torque generated by the water flow and system loads, including the friction and reverse loads of the generator. It is found that the incident flow velocity and the moment of inertia of the rotor have little effect on the averaged values of tip-speed ratios in the equilibrium stage under no-load conditions. In the system load calculations, four modes of the self-starting were found: stable equilibrium mode, unstable equilibrium mode, switch mode and halt mode. The dimensionless power coefficient in the simulations of passive rotation conditions is found to be, on average, 38% higher than those achieved in the simulations of forced rotation conditions.
Energy Technology Data Exchange (ETDEWEB)
Pouliot, D. [OZZ Energy Solutions, Concord, ON (Canada)
2006-07-01
Energy management is a continuum of directing and controlling energy use at an optimum level. A well-informed manager must know how much energy is used, what the costs are, what the loads are, and when the energy is used. Energy profiling uses remote site surveillance to enable the collection and precise measurement of actual consumption data for utilities. Energy profiling provides analysis, interpretation and reporting of the acquired energy information, which is displayed using graphics via the internet. Energy profiling can include various classes of information on energy use; building characteristics; weather data; energy prices; and energy demand-response event information. This presentation provided details of energy management and advanced metering infrastructure (AMI) tools developed by OZZ Corporation, a Canadian-owned energy services company based in the Greater Toronto Area (GTA). The company's AMI metering services include multi-vendor support, advanced meter reading, meter data management and bill processing, and web-based energy profiling and information services. The company's Energy Trakker software provides benchmarking, auditing and validation processes, as well as ongoing monitoring and verification. Case studies of 2 large residential rental complexes using energy management tools developed by the company were provided. It was concluded that effective energy management tools help to reduce operating costs, enhance tenant satisfaction and raise property values. Investment in energy data profiling will allow utilities to identify and act on savings opportunities. refs., tabs., figs.
Friction compensation in energy-based bilateral telemanipulation
Franken, M.C.J.; Misra, Sarthak; Stramigioli, Stefano
2010-01-01
In bilateral telemanipulation algorithms based on time-domain passivity, internal friction in the devices poses an additional energy drain. Based on a model of the friction, the dissipated energy can be estimated and reclaimed inside the energy balance of the control algorithm. As long as the
Friction Compensation in Energy-Based Bilateral Telemanipulation
Franken, M.C.J.; Misra, Sarthak; Stramigioli, Stefano
2010-01-01
In bilateral telemanipulation algorithms based on time-domain passivity, internal friction in the devices poses an additional energy drain. Based on a model of the friction, the dissipated energy can be estimated and reclaimed inside the energy balance of the control algorithm. As long as the
Holländer, Hartmut; Montasir Islam, Md.; Šimunek, Jirka
2017-04-01
Frozen soil has a major effect in many hydrologic processes, and its effects are difficult to predict. A prime example is flood forecasting during spring snowmelt within the Canadian Prairies. One key driver for the extent of flooding is the antecedent soil moisture and the possibility for water to infiltrate into frozen soils. Therefore, these situations are crucial for accurate flood prediction during every spring. The main objective of this study was to evaluate the water flow and heat transport within HYDRUS-1D version 4.16 and with Hansson's model, which is a detailed freezing/thawing module (Hansson et al., 2004), to predict the impact of frozen and partly frozen soil on infiltration. We developed a standardized data set of water flow and heat transport into (partial) frozen soil by laboratory experiments using fine sand. Temperature, soil moisture, and percolated water were observed at different freezing conditions as well as at thawing conditions. Significant variation in soil moisture was found between the top and the bottom of the soil column at the starting of the thawing period. However, with increasing temperature, the lower depth of the soil column showed higher moisture as the soil became enriched with moisture due to the release of heat by soil particles during the thawing cycle. We applied vadose zone modeling using the results from the laboratory experiments. The simulated water content by HYDRUS-1D 4.16 showed large errors compared to the observed data showing by negative Nash-Sutcliffe Efficiency. Hansson's model was not able to predict soil water fluxes due to its unstable behavior (Šimunek et al., 2016). The soil temperature profile simulated using HYDRUS-1D 4.16 was not able to predict the release of latent heat during the phase change of water that was visible in Hansson's model. Hansson's model includes the energy gain/loss due to the phase change in the amount of latent energy stored in the modified heat transport equation. However, in
Xu, Bin; Chen, Hongbing; Xia, Song
2017-03-01
In recent years, Piezoelectric Lead Zirconate Titanate (PZT) based active interfacial debonding defect detection approach for concrete-filled steel tubular (CFST) columns has been proposed and validated experimentally. In order to investigate the mechanism of the PZT based interfacial debonding detection approach, a multi-physics coupling finite element model (FEM) composed of surface-mounted PZT actuator, embedded PZT sensor and a rectangular CFST column is constructed to numerically simulate the stress wave propagation induced by the surface-mounted PZT actuator under different excitation signals with different frequency and amplitude. The measurements of the embedded PZT sensor in concrete core of the CFST columns with different interfacial debonding defect lengths and depths are determined numerically with transient dynamic analysis. The linearity between the PZT response and the input amplitude, the effect of different frequency and measurement distance are discussed and the stress wave fields of CFST members without and with interface debonding defects are compared. Then, the response of the embedded PZT in concrete core is analyzed with wavelet packet analysis. The root mean square deviation (RMSD) of wavelet packet energy spectrum of the PZT measurement is employed as an evaluation index for the interfacial debonding detection. The results showed that the defined index under continuous sinusoidal and sweep frequency signals changes with the interfacial defects length and depth and is capable of effectively identifying the interfacial debonding defect between the concrete core and the steel tubular. Moreover, the index under sweep frequency signal is more sensitive to the interfacial debonding. The simulation results indicate that the interfacial debonding defect leads to the changes in the propagation path, travel time and the magnitude of stress waves. The simulation results meet the findings from the previous experimental study by the authors and help
Numerical Estimation of Spectral Properties of Laser Based on Rate Equations
Directory of Open Access Journals (Sweden)
Jan Litvik
2016-01-01
Full Text Available Laser spectral properties are essential to evaluate the performance of optical communication systems. In general, the power spectral density of the phase noise has a crucial impact on spectral properties of the unmodulated laser signal. Here the white Gaussian noise and 1/f-noise are taken into the consideration. By utilizing the time-dependent realizations of the instantaneous optical power and the phase simultaneously, it is possible to estimate the power spectral density or alternatively the power spectrum of an unmodulated laser signal shifted to the baseband and thus estimate the laser linewidth. In this work, we report on the theoretical approach to analyse unmodulated real-valued high-frequency stationary random passband signal of laser, followed by presenting the numerical model of the distributed feedback laser to emulate the time-dependent optical power and the instantaneous phase, as two important time domain laser attributes. The laser model is based on numerical solving the rate equations using fourth-order Runge-Kutta method. This way, we show the direct estimation of the power spectral density and the laser linewidth, when time-dependent laser characteristics are known.
Energy Technology Data Exchange (ETDEWEB)
Chen, Xueli, E-mail: xlchen@xidian.edu.cn, E-mail: jimleung@mail.xidian.edu.cn; Yang, Defu; Zhang, Qitan; Liang, Jimin, E-mail: xlchen@xidian.edu.cn, E-mail: jimleung@mail.xidian.edu.cn [School of Life Science and Technology, Xidian University, Xi' an 710071 (China); Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education (China)
2014-05-14
Even though bioluminescence tomography (BLT) exhibits significant potential and wide applications in macroscopic imaging of small animals in vivo, the inverse reconstruction is still a tough problem that has plagued researchers in a related area. The ill-posedness of inverse reconstruction arises from insufficient measurements and modeling errors, so that the inverse reconstruction cannot be solved directly. In this study, an l{sub 1/2} regularization based numerical method was developed for effective reconstruction of BLT. In the method, the inverse reconstruction of BLT was constrained into an l{sub 1/2} regularization problem, and then the weighted interior-point algorithm (WIPA) was applied to solve the problem through transforming it into obtaining the solution of a series of l{sub 1} regularizers. The feasibility and effectiveness of the proposed method were demonstrated with numerical simulations on a digital mouse. Stability verification experiments further illustrated the robustness of the proposed method for different levels of Gaussian noise.
A microkernel design for component-based parallel numerical software systems.
Energy Technology Data Exchange (ETDEWEB)
Balay, S.
1999-01-13
What is the minimal software infrastructure and what type of conventions are needed to simplify development of sophisticated parallel numerical application codes using a variety of software components that are not necessarily available as source code? We propose an opaque object-based model where the objects are dynamically loadable from the file system or network. The microkernel required to manage such a system needs to include, at most: (1) a few basic services, namely--a mechanism for loading objects at run time via dynamic link libraries, and consistent schemes for error handling and memory management; and (2) selected methods that all objects share, to deal with object life (destruction, reference counting, relationships), and object observation (viewing, profiling, tracing). We are experimenting with these ideas in the context of extensible numerical software within the ALICE (Advanced Large-scale Integrated Computational Environment) project, where we are building the microkernel to manage the interoperability among various tools for large-scale scientific simulations. This paper presents some preliminary observations and conclusions from our work with microkernel design.
Numerical Study on Biaxial Seismic Performance of Reinforced Concrete Box Piers Based on OpenSees
Liu, Chuncheng; Lv, Chunlei; Wang, Chongyang; Yang, Geng; Huang, Dapeng; Zhang, Yiling
2017-12-01
In order to study the seismic performance of reinforced concrete box piers under biaxial loading, the hysteretic model of reinforced concrete box piers was established by selecting appropriate material model, constitutive relation, structural element type, and the corresponding boundary conditions and loading method based on OpenSees. The numerical simulation of the ductility of reinforced concrete box piers with different axial compression ratio, stirrup ratio and slenderness ratio under biaxial horizontal loading was conducted. The results of biaxial quasi-static tests and that of numerical simulation were compared. The analysis showed that the hysteretic behaviour of reinforced concrete box piers under biaxial loading could be well simulated and the degradation of strength and stiffness of box piers in the process of bidirectional cyclic loading could be reflected by OpenSees on the basis of the appropriate material constitutive model and structural element type. Furthermore, the influence of reinforcement ratio and concrete strength on the ductility of reinforced concrete box pier was studied by OpenSees.
A Confidence Index Approach Based on ERA-40 Data for Numerical Short Range Forecasts
Directory of Open Access Journals (Sweden)
Thomas Prenosil
2014-09-01
Full Text Available Critical weather related missions increasingly rely on highly automated numerical products, even if only limited computer capacities are available to generate them. This holds true especially for military tactical decision aids but also for civil requirements from firebrigades, the Red Cross or technical relief organizations. With respect to inherent atmospheric indeterminateness, a systematic quality control of numerical input turns out to become more and more essential for the users. As an economical alternative to the complex and expensive ensemble prediction method, the German Bundeswehr Geoinformation Centre has decided in favour of an analogue approach called similar synoptic situations (3s, which is based on ECMWF's ERA-40 re-analysis archive. Similarity is defined by a special distance measure for synoptic fields. The typical range of interest is 2500km×2500km$2500\\,\\text{km}\\times2500\\,\\text{km}$ in space with approximately one degree of horizontal resolution and up to 36 hours of forecast time. Historical 12, 24 and 36 hours ERA-40 forecast qualities are merged by 3s into a confidence index, indicating current anomalies of numerical quality versus monthly means in special areas of interest. As the results from the ERA-40 archive are used without any statistical adaption, this assessment is exclusively valid for trouble-free synoptic model runs in the short range. For a better understanding of the estimated anomalies in numerical forecast quality, the involved synoptic conditions are classified by a well established weather type classification. The overall method has been verified from 45 years of ERA-40 data and 10 years of GME forecasts from the Deutscher Wetterdienst. The 3s technique is highly flexible all over the globe with the exception of the tropics, because the present version includes the geostrophic approximation. At present, 3s runs operationally within four geographic areas: (1 Central Europe, (2 Kosovo with
Zhou, Shu-Wei; Xia, Cai-Chu; Zhao, Hai-Bin; Mei, Song-Hua; Zhou, Yu
2017-12-01
Compressed air energy storage (CAES) is a technology that uses compressed air to store surplus electricity generated from low power consumption time for use at peak times. This paper presents a thermo-mechanical modeling for the thermodynamic and mechanical responses of a lined rock cavern used for CAES. The simulation was accomplished in COMSOL Multiphysics and comparisons of the numerical simulation and some analytical solutions validated the thermo-mechanical modeling. Air pressure and temperatures in the sealing layer and concrete lining exhibited a similar trend of ‘up–down–down–up’ in one cycle. Significant temperature fluctuation occurred only in the concrete lining and sealing layer, and no strong fluctuation was observed in the host rock. In the case of steel sealing, principal stresses in the sealing layer were larger than those in the concrete and host rock. The maximum compressive stresses of the three layers and the displacement on the cavern surface increased with the increase of cycle number. However, the maximum tensile stresses exhibited the opposite trend. Polymer sealing achieved a relatively larger air temperature and pressure compared with steel and air-tight concrete sealing. For concrete layer thicknesses of 0 and 0.1 m and an initial air pressure of 4.5 MPa, the maximum rock temperature could reach 135 °C and 123 °C respectively in a 30 day simulation.
Handy, Timothy; Drake, R Paul; Zhiglo, Andrey
2013-01-01
We investigate the possibility of generating and studying turbulence in plasma by means of high-energy density laser-driven experiments. Our focus is to create supersonic, self-magnetized turbulence with characteristics that resemble those found in the interstellar medium (ISM). We consider a target made of a spherical core surrounded by a shell made of denser material. The shell is irradiated by a sequence of laser pulses sending inward-propagating shocks that convert the inner core into plasma and create turbulence. In the context of the evolution of the ISM, the shocks play the role of supernova remnant shocks and the core represents the ionized interstellar medium. We consider the effects of both pre-existing and self-generating magnetic fields and study the evolution of the system by means of two-dimensional numerical simulations. We find that the evolution of the turbulent core is generally, subsonic with rms-Mach number $M_t\\approx 0.2$. We observe an isotropic, turbulent velocity field with an inertia...
Analyzing asteroid reflectance spectra with numerical tools based on scattering simulations
Penttilä, Antti; Väisänen, Timo; Markkanen, Johannes; Martikainen, Julia; Gritsevich, Maria; Muinonen, Karri
2017-04-01
We are developing a set of numerical tools that can be used in analyzing the reflectance spectra of granular materials such as the regolith surface of atmosphereless Solar system objects. Our goal is to be able to explain, with realistic numerical scattering models, the spectral features arising when materials are intimately mixed together. We include the space-weathering -type effects in our simulations, i.e., mixing host mineral locally with small inclusions of another material in small proportions. Our motivation for this study comes from the present lack of such tools. The current common practice is to apply a semi-physical approximate model such as some variation of Hapke models [e.g., 1] or the Shkuratov model [2]. These models are expressed in a closed form so that they are relatively fast to apply. They are based on simplifications on the radiative transfer theory. The problem is that the validity of the model is not always guaranteed, and the derived physical properties related to particle scattering properties can be unrealistic [3]. We base our numerical tool into a chain of scattering simulations. Scattering properties of small inclusions inside an absorbing host matrix can be derived using exact methods solving the Maxwell equations of the system. The next step, scattering by a single regolith grain, is solved using a geometrical optics method accounting for surface reflections, internal absorption, and possibly the internal diffuse scattering. The third step involves the radiative transfer simulations of these regolith grains in a macroscopic planar element. The chain can be continued next with shadowing simulation over the target surface elements, and finally by integrating the bidirectional reflectance distribution function over the object's shape. Most of the tools in the proposed chain already exist, and one practical task for us is to tie these together into an easy-to-use toolchain that can be publicly distributed. We plan to open the
Demonstrating sustainable energy: A review-based model of sustainable energy demonstration projects
Bossink, Bart
2017-01-01
This article develops a model of sustainable energy demonstration projects, based on a review of 229 scientific publications on demonstrations in renewable and sustainable energy. The model addresses the basic organizational characteristics (aim, cooperative form, and physical location) and learning
A Web Based Puzzle for Energy Sources
Directory of Open Access Journals (Sweden)
Nilgun SECKEN
2006-07-01
Full Text Available At present many countries in the world consume too much fossil fuels such as petroleum, natural gas and coal to meet their energy needs. These fossil fuels are not renewable; their sources are limited and reducing gradually. More importantly they have been becoming more expensive day by day and their damage to the environment has been increasing. In spite of it, renewable energy sources are renewed and never run out. In addition there are many benefits of renewable energy. In this study a puzzle is prepared for primary-school students aiming at teaching of energy sources as a supplementary source. In the mean time, the puzzle we prepared reveals the advantages and disadvantages of renewable and fossil energy sources. Here, the student’s aim is to complete the puzzle by answering the questions respectively. .
Huang, Chao; Schoonover, Robert W; Wang, Lihong V; Anastasio, Mark A
2015-01-01
Photoacoustic computed tomography (PACT) is a rapidly emerging bioimaging modality that seeks to reconstruct an estimate of the absorbed optical energy density within an object. Conventional PACT image reconstruction methods assume a constant speed-of-sound (SOS), which can result in image artifacts when acoustic aberrations are significant. It has been demonstrated that incorporating knowledge of an object's SOS distribution into a PACT image reconstruction method can improve image quality. However, in many cases, the SOS distribution cannot be accurately and/or conveniently estimated prior to the PACT experiment. Because variations in the SOS distribution induce aberrations in the measured photoacoustic wavefields, certain information regarding an object's SOS distribution is encoded in the PACT measurement data. Based on this observation, a joint reconstruction (JR) problem has been proposed in which the SOS distribution is concurrently estimated along with the sought-after absorbed optical energy density ...
Numerical analysis of a two-pion correlation function based on a hydrodynamical model
Morita, K; Nakamura, H; Nonaka, C; Morita, Kenji; Muroya, Shin; Nakamura, Hiroki; Nonaka, Chiho
2000-01-01
We will numerically investgate two-particle correlation function of CERN--SPS 158 A GeV Pb+Pb central collisions in detail based on a (3+1)-dimensional relativistic hydrodynamical model with first order phase transition. We use the Yano-Koonin-Podgoretski\\u{\\i} parametrization as well as the usual Cartesian parametrization and analyze the pair momentum dependence of HBT radii extracted from the parametrizations. We find that the interpretation of the temporal radius parameters as the time duration in YKP parametrization is not available for the hydrodynamical model where the source became opaque naturally because of expansion and surface dominant freeze-out. Finally, effect of the phase transition on the source opacity is also discussed.
Numerical Simulation of Airliner Cabin Environment based on Various Inlet Angles
Directory of Open Access Journals (Sweden)
Zhuo Huan Hu
2014-07-01
Full Text Available The study of airflow transport in airliner cabins is extremely important in creating a comfortable environment. The air temperature field and velocity field in the airliner cabin have significant influence on the health of pilots and passengers. In this study, heat transfer based on numerical study was carried out to investigate the effects of natural convection and air distribution with different angles. The average Reynolds equation and low Reynolds number turbulence model were used to simulate the airflow in the cabin. The convective term of convection diffusion equation was implemented with higher-order accurate schemes. Mathematical statistics was adopted to process the final data. Results showed that the effect of the natural convection could be negligible. Additional studies presented that air temperature field and flow field were largely affected by various inlet angles. A set of optimum matching inlet vane angles that could create a comfortable environment was determined.
Numerical simulation of induction hardening of a cylindrical part based on multi-physics coupling
Tong, Daming; Gu, Jianfeng; Totten, George Edward
2017-04-01
An induction hardening process was simulated based on an electromagnetic-thermal-transformation coupled numerical model. Calculation of the microstructure fraction was introduced using a coupled electromagnetic-thermal field during heating and the temperature field of the subsequent cooling process. The isoconversional method was used to formulate the austenitization process during heating, model parameters were determined by continuous heating dilatometric curves, and JMAK and K-M equations were adopted to calculate the fraction of new phases formed during cooling. The temperature and microstructure evolution in a cylindrical part of JIS-SCM440 steel were simulated during the induction hardening process and the simulated temperature and final microstructure distribution fit well with experimental data. Simulation results also showed that the free cooling prior to spray quenching could be optimized to decrease the temperature gradient in the surface layer to avoid decomposition of austenite into non-martensite microstructure.
Directory of Open Access Journals (Sweden)
Bartlewska-Urban Monika
2016-03-01
Full Text Available The following study presents numerical calculations for establishing the impact of temperature changes on the process of distortion of bi-phase medium represented using Biot consolidation equations with Kelvin–Voigt rheological skeleton presented, on the example of thermo-consolidation of a pavement of expressway S17. We analyzed the behavior of the expressway under the action of its own weight, dynamic load caused by traffic and temperature gradient. This paper presents the application of the Biot consolidation model with the Kelvin–Voigt skeleton rheological characteristics and the influence of temperature on the deformation process is taken into account. A three-dimensional model of the medium was created describing the thermal consolidation of a porous medium. The 3D geometrical model of the area under investigation was based on data obtained from the land surveying and soil investigation of a 200 m long section of the expressway and its shoulders.
On the Nonlinear Behavior of the Piezoelectric Coupling on Vibration-Based Energy Harvesters
Directory of Open Access Journals (Sweden)
Luciana L. Silva
2015-01-01
Full Text Available Vibration-based energy harvesting with piezoelectric elements has an increasing importance nowadays being related to numerous potential applications. A wide range of nonlinear effects is observed in energy harvesting devices and the analysis of the power generated suggests that they have considerable influence on the results. Linear constitutive models for piezoelectric materials can provide inconsistencies on the prediction of the power output of the energy harvester, mainly close to resonant conditions. This paper investigates the effect of the nonlinear behavior of the piezoelectric coupling. A one-degree of freedom mechanical system is coupled to an electrical circuit by a piezoelectric element and different coupling models are investigated. Experimental tests available in the literature are employed as a reference establishing the best matches of the models. Subsequently, numerical simulations are carried out showing different responses of the system indicating that nonlinear piezoelectric couplings can strongly modify the system dynamics.
Flow based vs. demand based energy-water modelling
Rozos, Evangelos; Nikolopoulos, Dionysis; Efstratiadis, Andreas; Koukouvinos, Antonios; Makropoulos, Christos
2015-04-01
The water flow in hydro-power generation systems is often used downstream to cover other type of demands like irrigation and water supply. However, the typical case is that the energy demand (operation of hydro-power plant) and the water demand do not coincide. Furthermore, the water inflow into a reservoir is a stochastic process. Things become more complicated if renewable resources (wind-turbines or photovoltaic panels) are included into the system. For this reason, the assessment and optimization of the operation of hydro-power systems are challenging tasks that require computer modelling. This modelling should not only simulate the water budget of the reservoirs and the energy production/consumption (pumped-storage), but should also take into account the constraints imposed by the natural or artificial water network using a flow routing algorithm. HYDRONOMEAS, for example, uses an elegant mathematical approach (digraph) to calculate the flow in a water network based on: the demands (input timeseries), the water availability (simulated) and the capacity of the transmission components (properties of channels, rivers, pipes, etc.). The input timeseries of demand should be estimated by another model and linked to the corresponding network nodes. A model that could be used to estimate these timeseries is UWOT. UWOT is a bottom up urban water cycle model that simulates the generation, aggregation and routing of water demand signals. In this study, we explore the potentials of UWOT in simulating the operation of complex hydrosystems that include energy generation. The evident advantage of this approach is the use of a single model instead of one for estimation of demands and another for the system simulation. An application of UWOT in a large scale system is attempted in mainland Greece in an area extending over 130×170 km². The challenges, the peculiarities and the advantages of this approach are examined and critically discussed.
Díaz, J I; Hidalgo, A; Tello, L
2014-10-08
We study a climatologically important interaction of two of the main components of the geophysical system by adding an energy balance model for the averaged atmospheric temperature as dynamic boundary condition to a diagnostic ocean model having an additional spatial dimension. In this work, we give deeper insight than previous papers in the literature, mainly with respect to the 1990 pioneering model by Watts and Morantine. We are taking into consideration the latent heat for the two phase ocean as well as a possible delayed term. Non-uniqueness for the initial boundary value problem, uniqueness under a non-degeneracy condition and the existence of multiple stationary solutions are proved here. These multiplicity results suggest that an S-shaped bifurcation diagram should be expected to occur in this class of models generalizing previous energy balance models. The numerical method applied to the model is based on a finite volume scheme with nonlinear weighted essentially non-oscillatory reconstruction and Runge-Kutta total variation diminishing for time integration.
Díaz, J. I.; Hidalgo, A.; Tello, L.
2014-01-01
We study a climatologically important interaction of two of the main components of the geophysical system by adding an energy balance model for the averaged atmospheric temperature as dynamic boundary condition to a diagnostic ocean model having an additional spatial dimension. In this work, we give deeper insight than previous papers in the literature, mainly with respect to the 1990 pioneering model by Watts and Morantine. We are taking into consideration the latent heat for the two phase ocean as well as a possible delayed term. Non-uniqueness for the initial boundary value problem, uniqueness under a non-degeneracy condition and the existence of multiple stationary solutions are proved here. These multiplicity results suggest that an S-shaped bifurcation diagram should be expected to occur in this class of models generalizing previous energy balance models. The numerical method applied to the model is based on a finite volume scheme with nonlinear weighted essentially non-oscillatory reconstruction and Runge–Kutta total variation diminishing for time integration. PMID:25294969
Algorithms, data structures, and numerics for likelihood-based phylogenetic inference of huge trees
Directory of Open Access Journals (Sweden)
Izquierdo-Carrasco Fernando
2011-12-01
Full Text Available Abstract Background The rapid accumulation of molecular sequence data, driven by novel wet-lab sequencing technologies, poses new challenges for large-scale maximum likelihood-based phylogenetic analyses on trees with more than 30,000 taxa and several genes. The three main computational challenges are: numerical stability, the scalability of search algorithms, and the high memory requirements for computing the likelihood. Results We introduce methods for solving these three key problems and provide respective proof-of-concept implementations in RAxML. The mechanisms presented here are not RAxML-specific and can thus be applied to any likelihood-based (Bayesian or maximum likelihood tree inference program. We develop a new search strategy that can reduce the time required for tree inferences by more than 50% while yielding equally good trees (in the statistical sense for well-chosen starting trees. We present an adaptation of the Subtree Equality Vector technique for phylogenomic datasets with missing data (already available in RAxML v728 that can reduce execution times and memory requirements by up to 50%. Finally, we discuss issues pertaining to the numerical stability of the Γ model of rate heterogeneity on very large trees and argue in favor of rate heterogeneity models that use a single rate or rate category for each site to resolve these problems. Conclusions We address three major issues pertaining to large scale tree reconstruction under maximum likelihood and propose respective solutions. Respective proof-of-concept/production-level implementations of our ideas are made available as open-source code.
Numerical simulation and comparison of nonlinear self-focusing based on iteration and ray tracing
Li, Xiaotong; Chen, Hao; Wang, Weiwei; Ruan, Wangchao; Zhang, Luwei; Cen, Zhaofeng
2017-05-01
Self-focusing is observed in nonlinear materials owing to the interaction between laser and matter when laser beam propagates. Some of numerical simulation strategies such as the beam propagation method (BPM) based on nonlinear Schrödinger equation and ray tracing method based on Fermat's principle have applied to simulate the self-focusing process. In this paper we present an iteration nonlinear ray tracing method in that the nonlinear material is also cut into massive slices just like the existing approaches, but instead of paraxial approximation and split-step Fourier transform, a large quantity of sampled real rays are traced step by step through the system with changing refractive index and laser intensity by iteration. In this process a smooth treatment is employed to generate a laser density distribution at each slice to decrease the error caused by the under-sampling. The characteristics of this method is that the nonlinear refractive indices of the points on current slice are calculated by iteration so as to solve the problem of unknown parameters in the material caused by the causal relationship between laser intensity and nonlinear refractive index. Compared with the beam propagation method, this algorithm is more suitable for engineering application with lower time complexity, and has the calculation capacity for numerical simulation of self-focusing process in the systems including both of linear and nonlinear optical media. If the sampled rays are traced with their complex amplitudes and light paths or phases, it will be possible to simulate the superposition effects of different beam. At the end of the paper, the advantages and disadvantages of this algorithm are discussed.
A Cell-Based Framework for Numerical Modeling of Electrical Conduction in Cardiac Tissue
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Aslak Tveito
2017-10-01
Full Text Available In this paper, we study a mathematical model of cardiac tissue based on explicit representation of individual cells. In this EMI model, the extracellular (E space, the cell membrane (M, and the intracellular (I space are represented as separate geometrical domains. This representation introduces modeling flexibility needed for detailed representation of the properties of cardiac cells including their membrane. In particular, we will show that the model allows ion channels to be non-uniformly distributed along the membrane of the cell. Such features are difficult to include in classical homogenized models like the monodomain and bidomain models frequently used in computational analyses of cardiac electrophysiology. The EMI model is solved using a finite difference method (FDM and two variants of the finite element method (FEM. We compare the three schemes numerically, reporting on CPU-efforts and convergence rates. Finally, we illustrate the distinctive capabilities of the EMI model compared to classical models by simulating monolayers of cardiac cells with heterogeneous distributions of ionic channels along the cell membrane. Because of the detailed representation of every cell, the computational problems that result from using the EMI model are much larger than for the classical homogenized models, and thus represent a computational challenge. However, our numerical simulations indicate that the FDM scheme is optimal in the sense that the computational complexity increases proportionally to the number of cardiac cells in the model. Moreover, we present simulations, based on systems of equations involving ~117 million unknowns, representing up to ~16,000 cells. We conclude that collections of cardiac cells can be simulated using the EMI model, and that the EMI model enable greater modeling flexibility than the classical monodomain and bidomain models.
Hydrodynamics of Lock-exchange Turbidity Currents down a Slope Based on Direct Numerical Simulation
Zhao, Liang; Lin, Ying-Tien; Hu, Peng; Liang, Xiaolong; He, Zhiguo
2016-01-01
Turbidity currents play a vital role in various geophysical environments. However, until now, few studies have taken into the effects of both suspended particle and slope on its evolution, which requires a precise information of the spatio-temporal flow field. Hence, this study presents high-resolution and two-dimensional direct numerical simulations (DNS) of lock-exchange turbidity currents down a slope. By analyzing front velocity, water entrainment, and energy budget, the factors that affect the driving force, thus the development of the turbidity current, are detailedly investigated. The front velocity history exhibits three distinct stages over time, i.e., a short acceleration stage, a quasi-constant stage, and a deceleration stage. The calculation of the entrainment ratio shows that the mixing due to the collapse of the dense fluid is much stronger than that due to the Kelvin-Helmholtz instabilities and turbulent billows. For a turbidity current down a slope, the entrainment volume of ambient water decr...
A Web Based Puzzle for Energy Sources
Secken, Nilgun
2006-01-01
At present many countries in the world consume too much fossil fuels such as petroleum, natural gas and coal to meet their energy needs. These fossil fuels are not renewable; their sources are limited and reducing gradually. More importantly they have been becoming more expensive day by day and their damage to the environment has been increasing. In spite of it, renewable energy sources are renewed and never run out. In addition there are many benefits of renewable energy. In this study a puz...
UAV based hydromorphological mapping of a river reach to improve hydrodynamic numerical models
Lükő, Gabriella; Baranya, Sándor; Rüther, Nils
2017-04-01
Unmanned Aerial Vehicles (UAVs) are increasingly used in the field of engineering surveys. In river engineering, or in general, water resources engineering, UAV based measurements have a huge potential. For instance, indirect measurements of the flow discharge using e.g. large-scale particle image velocimetry (LSPIV), particle tracking velocimetry (PTV), space-time image velocimetry (STIV) or radars became a real alternative for direct flow measurements. Besides flow detection, topographic surveys are also essential for river flow studies as the channel and floodplain geometry is the primary steering feature of the flow. UAVs can play an important role in this field, too. The widely used laser based topographic survey method (LIDAR) can be deployed on UAVs, moreover, the application of the Structure from Motion (SfM) method, which is based on images taken by UAVs, might be an even more cost-efficient alternative to reveal the geometry of distinct objects in the river or on the floodplain. The goal of this study is to demonstrate the utilization of photogrammetry and videogrammetry from airborne footage to provide geometry and flow data for a hydrodynamic numerical simulation of a 2 km long river reach in Albania. First, the geometry of the river is revealed from photogrammetry using the SfM method. Second, a more detailed view of the channel bed at low water level is taken. Using the fine resolution images, a Matlab based code, BASEGrain, developed by the ETH in Zürich, will be applied to determine the grain size characteristics of the river bed. This information will be essential to define the hydraulic roughness in the numerical model. Third, flow mapping is performed using UAV measurements and LSPIV method to quantitatively asses the flow field at the free surface and to estimate the discharge in the river. All data collection and analysis will be carried out using a simple, low-cost UAV, moreover, for all the data processing, open source, freely available
Directory of Open Access Journals (Sweden)
A. Balaguer-Beser
2017-08-01
Full Text Available In this paper, a comparison between the results obtained in laboratory experiments and those calculated by a numerical simulation of shallow water equations in an open channel is performed, considering the energy losses that occur as it passes through a local narrowing of the cross section. The mathematical model that simulates this physical phenomenon is governed by a partial differential equations system whose solution provides the water depth and the flow rate per unit of width, which is related to the velocity of the water. Such movement is controlled primarily by the force of gravity, being fundamental the relationship between it and the inertial forces. In the present study we have also taken into account energy losses caused by friction of the water with the contours and local losses caused by obstacles or changes in the width of the channel. A numerical scheme based on a high-order finite volume method has been used for obtaining the solutions of such model. Two type of laboratory tests have been simulated. The first type represents a slow transition regime, upstream and downstream of a narrowing in the channel. The second type represents a subcritical flow upstream, a narrowing that works as a control (regime change and a downstream supercritical flow. Numerical-experimental comparison demonstrates the importance of adequately modeling of the different physical phenomena involved in the process, and the proper imposition of the boundary conditions of the problem.
Energy Based Acoustic Measurement Senors Project
National Aeronautics and Space Administration — This research focuses on fully developing energy density sensors that will yield a significant benefit both for measurements of interest to NASA, as well as for...
Hydrogen based global renewable energy network
Energy Technology Data Exchange (ETDEWEB)
Akai, Makoto [Mechanical Engineering Laboratory, AIST, MITI, Namiki, Tsukuba (Japan)
1993-12-31
In the last quarter of this century, global environmental problem has emerged as a major scientific, political and social issue. Specific Problems include: depletion of ozone layer by chlorofluorocarbons (CFCs), acid rain, destruction of tropical forests and desertification, pollution of the sea and global wanning due to the greenhouse effect by carbon dioxide and others. Among these problems, particular attention of the world has been focused on the global warming because it has direct linkage to energy consumption which our economic development depends on so far. On the other hand, the future program of The Sunshine Project for alternative energy technology R&D, The Moonlight Project for energy conservation technology R&D, and The Global Environmental Technology Program for environmental problem mitigating technology R&D which are Japan`s national projects being promoted by their Agency of Industrial Science and Technology (AIST) in the Ministry of International Trade and Industry have been reexamined in view of recent changes in the situations surrounding new energy technology. In this regard, The New Sunshine Program will be established by integrating these three activities to accelerate R&D in the field of energy and environmental technologies. In the reexamination, additional stress has been laid on the contribution to solving global environmental problem through development of clean renewable energies which constitute a major part of the {open_quotes}New Earth 21{close_quotes}, a comprehensive, long-term and international cooperative program proposed by MITI. The present paper discusses the results of feasibility study on hydrogen energy system leading to the concept of WE-NET following a brief summary on R&D status on solar and wind energy in Japan.
Smart Home Energy Management Based on Zigbee
E.Mallikarjuna
2015-01-01
Today organizations use IEEE 802.15&Zigbee to effectively deliver solutions for a variety of areas including consumer electronic device control, energy management and efficiency home and commercial building automation as well as industrial plant management. The smart home energy network has gained widespread attentions due to its flexible integrati- ion into everyday life. This next generation green home system transparently unifies various home appliances smart sensors &wireless communicati...
Numerical Research of Aerodynamic Characteristic Effects of Base Jet on Supersonic Rocket
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Juanmian Lei
2013-01-01
Full Text Available Based on finite volume method, the interaction between base jet and supersonic flow around the rocket is simulated by Navier-Stokes equations with SST k-ω turbulence model and implicit algorithm. The pressure contours, the streamline patterns, and the variation of the aerodynamic characteristics of the rocket with the flying altitude, Mach number, and the angle of attack are shown and analyzed. Numerical results demonstrate that in supersonic flow, the base jet has a noticeable effect on the surface pressure of the body and the tails, leading to the decreases of the coefficients of the normal force, the pitching moment, and the pressure center. Furthermore, the higher the flying altitude, the more grave decreases of the coefficients of the normal force, the pitching moment and the pressure center. However, with the increase of Mach number, the more grave the decreases of the normal force coefficient and the pitch moment coefficient are found, while the less grave decrease is found with the pressure center coefficient. With the increase of the angle of attack, the more grave decreases are found with the coefficients of the normal force and the pitching moment, while the decrease of the pressure center coefficient remains almost the same.
Directory of Open Access Journals (Sweden)
Jiang Lei
2015-01-01
Full Text Available Direct numerical simulation (DNS of a round jet in crossflow based on lattice Boltzmann method (LBM is carried out on multi-GPU cluster. Data parallel SIMT (single instruction multiple thread characteristic of GPU matches the parallelism of LBM well, which leads to the high efficiency of GPU on the LBM solver. With present GPU settings (6 Nvidia Tesla K20M, the present DNS simulation can be completed in several hours. A grid system of 1.5 × 108 is adopted and largest jet Reynolds number reaches 3000. The jet-to-free-stream velocity ratio is set as 3.3. The jet is orthogonal to the mainstream flow direction. The validated code shows good agreement with experiments. Vortical structures of CRVP, shear-layer vortices and horseshoe vortices, are presented and analyzed based on velocity fields and vorticity distributions. Turbulent statistical quantities of Reynolds stress are also displayed. Coherent structures are revealed in a very fine resolution based on the second invariant of the velocity gradients.
Energy Sharing Framework for Microgrid-Powered Cellular Base Stations
Farooq, Muhammad Junaid
2017-02-07
Cellular base stations (BSs) are increasingly becoming equipped with renewable energy generators to reduce operational expenditures and carbon footprint of wireless communications. Moreover, advancements in the traditional electricity grid allow two-way power flow and metering that enable the integration of distributed renewable energy generators at BS sites into a microgrid. In this paper, we develop an optimized energy management framework for microgrid-connected cellular BSs that are equipped with renewable energy generators and finite battery storage to minimize energy cost. The BSs share excess renewable energy with others to reduce the dependency on the conventional electricity grid. Three cases are investigated where the renewable energy generation is unknown, perfectly known, and partially known ahead of time. For the partially known case where only the statistics of renewable energy generation are available, stochastic programming is used to achieve a conservative solution. Results show the time varying energy management behaviour of the BSs and the effect of energy sharing between them.
Dyachenko, N. N.; Dyachenko, L. I.
2014-08-01
The results of numerical investigation of a multiphase flow considering coagulation, crushing and crystallization of the particles of polydispersed condensate in the nozzles of solid-propellant rocket engine are presented. The influence of particles crystallization on the energy characteristics of the engine is shown.
Numerical simulation based on core analysis of a single fracture in an Enhanced Geothermal System
Jarrahi, Miad; Holländer, Hartmut
2017-04-01
The permeability of reservoirs is widely affected by the presence of fractures dispersed within them, as they form superior paths for fluid flow. Core analysis studies the fractures characteristics and explains the fluid-rock interactions to provide the information of permeability and saturation of a hydraulic fracturing reservoir or an enhanced geothermal system (EGS). This study conducted numerical simulations of a single fracture in a Granite core obtained from a depth of 1890 m in borehole EPS1 from Soultz-sous-Forêts, France. Blaisonneau et al. (2016) designed the apparatus to investigate the complex physical phenomena on this cylindrical sample. The method of the tests was to percolate a fluid through a natural fracture contained in a rock sample, under controlled thermo-hydro-mechanical conditions. A divergent radial flow within the fracture occurred due to the injection of fluid into the center of the fracture. The tests were performed within a containment cell with a normal stress of 2.6, 4.9, 7.2 and 9.4 MPa loading on the sample perpendicular to the fracture plane. This experiment was numerically performed to provide an efficient numerical method by modeling single phase flow in between the fracture walls. Detailed morphological features of the fracture such as tortuosity and roughness, were obtained by image processing. The results included injection pressure plots with respect to injection flow rate. Consequently, by utilizing Hagen-Poiseuille's cubic law, the equivalent hydraulic aperture size, of the fracture was derived. Then, as the sample is cylindrical, to modify the Hagen-Poiseuille's cubic law for circular parallel plates, the geometric relation was applied to obtain modified hydraulic aperture size. Finally, intrinsic permeability of the fracture under each mechanical normal stress was evaluated based on modified hydraulic aperture size. The results were presented in two different scenarios, before and after reactive percolation test, to
DEFF Research Database (Denmark)
Dowlatabadi, Mohammadkazem Bakhshizadeh; Blaabjerg, Frede; Hjerrild, Jesper
2017-01-01
Some couplings exist between the positive- and negative-sequence impedances of a voltage sourced power converter especially in the low frequency range due to the nonlinearities and low bandwidth control loops like the PLL. In this paper, a new numerical method based on the Harmonic Transfer...... these couplings a matrix based method should be used. No information about the structure of the converter is needed and elements are modelled as black boxes with known terminal characteristics. The proposed method is applicable for both power quality (harmonic and inter-harmonic emissions) and stability studies...... Function for analysis of the Linear Time Periodic systems is presented, which is able to handle these couplings. In a balanced three-phase system, there is only one coupling term, but in an unbalanced (asymmetrical) system, there are more couplings, and therefore, in order to study the interactions between...
Numerical simulation of microwave ablation incorporating tissue contraction based on thermal dose
Liu, Dong; Brace, Christopher L.
2017-03-01
Tissue contraction plays an important role during high temperature tumor ablation, particularly during device characterization, treatment planning and imaging follow up. We measured such contraction in 18 ex vivo bovine liver samples during microwave ablation by tracking fiducial motion on CT imaging. Contraction was then described using a thermal dose dependent model and a negative thermal expansion coefficient based on the empirical data. FEM simulations with integrated electromagnetic wave propagation, heat transfer, and structural mechanics were evaluated using temperature-dependent dielectric properties and the negative thermal expansion models. Simulated temperature and displacement curves were then compared with the ex vivo experimental results on different continuous output powers. The optimized thermal dose model indicated over 50% volumetric contraction occurred at the temperature over 102.1 °C. The numerical simulation results on temperature and contraction-induced displacement showed a good agreement with experimental results. At microwave powers of 55 W, the mean errors on temperature between simulation and experimental results were 8.25%, 2.19% and 5.67% at 5 mm, 10 mm and 20 mm radially from the antenna, respectively. The simulated displacements had mean errors of 16.60%, 14.08% and 23.45% at the same radial locations. Compared to the experimental results, the simulations at the other microwave powers had larger errors with 10-40% mean errors at 40 W, and 10-30% mean errors at 25 W. The proposed model is able to predict temperature elevation and simulate tissue deformation during microwave ablation, and therefore may be incorporated into treatment planning and clinical translation from numerical simulations.
Numerical modeling of NO{sub x} reduction using pyrolysis products from biomass-based materials
Energy Technology Data Exchange (ETDEWEB)
Pisupati, Sarma V.; Bhalla, Sumeet [Department of Energy and Mineral Engineering, The Pennsylvania State University, 110 Hosler Building, University Park, PA 16802 (United States)
2008-02-15
Pyrolysis products of biomass (bio-oils) have been shown to cause a reduction in NO{sub x} emissions when used as reburn fuel in combustion systems. When these bio-oils are processed with lime, calcium is ion-exchanged and the product is called BioLime trademark. BioLime trademark, when introduced into a combustion chamber, causes oils to pyrolyze and reduce NO{sub x} emissions through reburn mechanisms while simultaneously causing Ca to react with SO{sub 2}. Thus NO{sub x} and SO{sub 2} emissions are reduced at the same time. The devolatilization rates of two biomass-based materials were studied using TGA and were related to the yield of pyrolysis gases and char during flash pyrolysis. Numerical simulations using CHEMKIN to model NO reduction through homogeneous gas phase reactions were reported. The numerical predictions were then compared to NO{sub x} emission levels from experiments in a down-fired combustor (DFC) to validate the model. A difference in NO reduction was observed by use of different bio-oils under similar operating conditions. This is believed to be due to the difference in yield of flash pyrolysis products of bio-oils. Also, different pyrolysis gases have different NO{sub x} reduction potentials. Knowledge of the relative contribution of pyrolysis gases in NO reduction will help choose a feedstock of biomass that will aid in increasing the yield of the desired species. A parametric analysis was done using the model to study the effect of varying concentrations of hydrocarbons, CO{sub 2}, CO, and H{sub 2}, and the results were then verified using a flow reactor. The analysis showed that hydrocarbons were mainly responsible for causing reduction in emissions of NO, whereas CO{sub 2}, CO, and H{sub 2} have very little effect on NO reduction. (author)
Enhanced Physics-Based Numerical Schemes for Two Classes of Turbulence Models
Directory of Open Access Journals (Sweden)
Leo G. Rebholz
2009-01-01
Full Text Available We present enhanced physics-based finite element schemes for two families of turbulence models, the NS- models and the Stolz-Adams approximate deconvolution models. These schemes are delicate extensions of a method created for the Navier-Stokes equations in Rebholz (2007, that achieve high physical fidelity by admitting balances of both energy and helicity that match the true physics. The schemes' development requires carefully chosen discrete curl, discrete Laplacian, and discrete filtering operators, in order to permit the necessary differential operator commutations.
Wideband energy harvesting based on mixed connection of piezoelectric oscillators
Wu, P. H.; Chen, Y. J.; Li, B. Y.; Shu, Y. C.
2017-09-01
An approach for wideband energy harvesting together with power enhancement is proposed by integrating multiple piezoelectric oscillators with mixed parallel-series connection. This gives rise to the feasibility of shifting the operation frequency band to the dominant frequency domain of ambient excitations. There are two types of connection patterns discussed here: the p-type (s-type) is the parallel (series) connection of all sets of oscillators where some of them may be connected in series (parallel). In addition, the standard interface circuit used for electric rectification is adopted here. The analytic estimates of output power are derived and explicitly expressed in terms of different matrix formulations for these two connection patterns. They are subsequently validated and are found in good agreement with numerical simulations and experimental observations. Finally, the experimental results from the mixed connection of 4 piezoelectric oscillators show that the peak power of each array is about 3.4 times higher than that generated by a single piezoelectric oscillator. In addition, the bandwidth of the array capable of switching connection patterns is around 2.8 times wider than that based on a single array configuration. Hence, the effective bandwidth is enlarged without the loss of peak power.
Critical experiments analyses by using 70 energy group library based on ENDF/B-VI
Energy Technology Data Exchange (ETDEWEB)
Tahara, Yoshihisa; Matsumoto, Hideki [Mitsubishi Heavy Industries Ltd., Yokohama (Japan). Nuclear Energy Systems Engineering Center; Huria, H.C.; Ouisloumen, M.
1998-03-01
The newly developed 70-group library has been validated by comparing kinf from a continuous energy Monte-Carlo code MCNP and two dimensional spectrum calculation code PHOENIX-CP. The code employs Discrete Angular Flux Method based on Collision Probability. The library has been also validated against a large number of critical experiments and numerical benchmarks for assemblies with MOX and Gd fuels. (author)
Numerical study of shear thickening fluid with discrete particles embedded in a base fluid
Directory of Open Access Journals (Sweden)
W Zhu
2016-09-01
Full Text Available The Shear Thickening Fluid (STF is a dilatant material, which displays non-Newtonian characteristics in its unique ability to transit from a low viscosity fluid to a high viscosity fluid. The research performed investigates the STF behavior by modeling and simulation of the interaction between the base flow and embedded rigid particles when subjected to shear stress. The model considered the Lagrangian description of the rigid particles and the Eulerian description of fluid flow. The numerical analysis investigated key parameters such as applied flow acceleration, particle distribution and arrangement, volume concentration of particles, particle size, shape and their behavior in a Newtonian and non-Newtonian fluid base. The fluid-particle interaction model showed that the arrangement, size, shape and volume concentration of the particles had a significant effect on the behavior of the STF. Although non-conclusive, the addition of particles in non-Newtonian fluids showed a promising trend of improved shear thickening effects at high shear strain rates.
New insights in quantum chemical topology studies using numerical grid-based analyses.
Kozlowski, David; Pilmé, Julien
2011-11-30
New insights in Quantum Chemical Topology of one-electron density functions have been proposed here by using a recent grid-based algorithm (Tang et al., J Phys Condens Matter 2009, 21, 084204), initially designed for the decomposition of the electron density. Beyond the charge analysis, we show that this algorithm is suitable for different scalar functions showing a more complex topology, that is, the Laplacian of the electron density, the electron localization function (ELF), and the molecular electrostatic potential (MEP). This algorithm makes use of a robust methodology enabling to numerically assign the data points of three-dimensional grids to basin volumes, and it has the advantage of requiring only the values of the scalar function without details on the wave function used to build the grid. Our implementation is briefly outlined (program named TopChem), its capabilities are examined, and technical aspects in terms of CPU requirement and accuracy of the results are discussed. Illustrative examples for individual molecules and crystalline solids obtained with gaussian and plane-wave-based density functional theory calculations are presented. Special attention was given to the MEP because its topological analysis is complex and scarce. Copyright © 2011 Wiley Periodicals, Inc.
Numerical Analysis of Hydrodynamics for Bionic Oscillating Hydrofoil Based on Panel Method
Directory of Open Access Journals (Sweden)
Gang Xue
2016-01-01
Full Text Available The kinematics model based on the Slender-Body theory is proposed from the bionic movement of real fish. The Panel method is applied to the hydrodynamic performance analysis innovatively, with the Gauss-Seidel method to solve the Navier-Stokes equations additionally, to evaluate the flexible deformation of fish in swimming accurately when satisfying the boundary conditions. A physical prototype to mimic the shape of tuna is developed with the revolutionized technology of rapid prototyping manufacturing. The hydrodynamic performance for rigid oscillating hydrofoil is analyzed with the proposed method, and it shows good coherence with the cases analyzed by the commercial software Fluent and the experimental data from robofish. Furthermore, the hydrodynamic performance of coupled hydrofoil, which consisted of flexible fish body and rigid caudal fin, is analyzed with the proposed method. It shows that the caudal fin has great influence on trailing vortex shedding and the phase angle is the key factor on hydrodynamic performance. It is verified that the shape of trailing vortex is similar to the image of the motion curve at the trailing edge as the assumption of linear vortex plane under the condition of small downwash velocity. The numerical analysis of hydrodynamics for bionic movement based on the Panel method has certain value to reveal the fish swimming mechanism.
Saleh, Mohamed Nasr
2016-01-08
Damage initiation and evolution of three-dimensional (3D) orthogonal woven carbon fibre composite (3DOWC) is investigated experimentally and numerically. Meso-scale homogenisation of the representative volume element (RVE) is utilised to predict the elastic properties, simulate damage initiation and evolution when loaded in tension. The effect of intra-yarns transverse cracking and shear diffused damage on the in-plane transverse modulus and shear modulus is investigated while one failure criterion is introduced to simulate the matrix damage. The proposed model is based on two major assumptions. First, the effect of the binder yarns, on the in-plane properties, is neglected, so the 3DOWC unit cell can be approximated as a (0o/90o) cross-ply laminate. Second, a micro-mechanics based damage approach is used at the meso-scale, so damage indicators can be correlated, explicitly, to the density of cracks within the material. Results from the simulated RVE are validated against experimental results along the warp (0o direction) and weft (90o direction). This approach paves the road for more predictive models as damage evolution laws are obtained from micro mechanical considerations and rely on few well-defined material parameters. This largely differs from classical damage mechanics approaches in which the evolution law is obtained by retrofitting experimental observations.
Directory of Open Access Journals (Sweden)
Yaqing Liu
2016-06-01
Full Text Available Automatically extracting quantities and generating final answers for numerical attributes is very useful in many occasions, including question answering, image processing, human-computer interaction, etc. A common approach is to learn linguistics templates or wrappers and employ some algorithm or model to generate a final answer. However, building linguistics templates or wrappers is a tough task for builders. In addition, linguistics templates or wrappers are domain-dependent. To make the builder escape from building linguistics templates or wrappers, we propose a new approach to final answer generation based on Predicates-Units Table (PUT, a mini domain-independent knowledge base. It is deserved to point out that, in the following cases, quantities are not represented well. Quantities are absent of units. Quantities are perhaps wrong for a given question. Even if all of them are represented well, their units are perhaps inconsistent. These cases have a strong impact on final answer solving. One thousand nine hundred twenty-six real queries are employed to test the proposed method, and the experimental results show that the average correctness ratio of our approach is 87.1%.
Directory of Open Access Journals (Sweden)
Eleonora Bilotta
2014-01-01
Full Text Available Chaotic dynamics of numerous memristor-based circuits is widely reported in literature. Recently, some works have appeared which study the problem of synchronization control of these systems in a master-slave configuration. In the present paper, the spontaneous dynamic behavior of two chaotic memristor-based Chua’s circuits, mutually interacting through a coupling resistance, was studied via computer simulations in order to study possible self-organized synchronization phenomena. The used memristor is a flux controlled memristor with a cubic nonlinearity, and it can be regarded as a time-varying memductance. The memristor, in effect, retains memory of its past dynamic and any difference in the initial conditions of the two circuits results in different values of the corresponding memductances. In this sense, due to the memory effect of the memristor, even if coupled circuits have the same parameters they do not constitute two completely identical chaotic oscillators. As is known, for nonidentical chaotic systems, in addition to complete synchronizations (CS other weaker forms of synchronization which provide correlations between the signals of the two systems can also occur. Depending on initial conditions and coupling strength, both chaotic and nonchaotic synchronization are observed for the system considered in this work.
Directory of Open Access Journals (Sweden)
Jingjing He
2016-08-01
Full Text Available Structural health monitoring has been studied by a number of researchers as well as various industries to keep up with the increasing demand for preventive maintenance routines. This work presents a novel method for reconstruct prompt, informed strain/stress responses at the hot spots of the structures based on strain measurements at remote locations. The structural responses measured from usage monitoring system at available locations are decomposed into modal responses using empirical mode decomposition. Transformation equations based on finite element modeling are derived to extrapolate the modal responses from the measured locations to critical locations where direct sensor measurements are not available. Then, two numerical examples (a two-span beam and a 19956-degree of freedom simplified airfoil are used to demonstrate the overall reconstruction method. Finally, the present work investigates the effectiveness and accuracy of the method through a set of experiments conducted on an aluminium alloy cantilever beam commonly used in air vehicle and spacecraft. The experiments collect the vibration strain signals of the beam via optical fiber sensors. Reconstruction results are compared with theoretical solutions and a detailed error analysis is also provided.
Mishra, A. K.; Catalan, Jorge; Camacho, Diana; Martinez, Miguel; Hodges, D.
2017-08-01
Solution processed organic-inorganic metal halide perovskite based solar cells are emerging as a new cost effective photovoltaic technology. In the context of increasing the power conversion efficiency (PCE) and sustainability of perovskite solar cells (PSC) devices, we comprehensively analyzed a physics-based numerical modelling for doped and un-doped PSC devices. Our analytics emphasized the role of different charge carrier layers from the view point of interfacial adhesion and its influence on charge extraction rate and charge recombination mechanism. Morphological and charge transport properties of perovskite thin film as a function of device architecture are also considered to investigate the photovoltaic properties of PSC. We observed that photocurrent is dominantly influenced by interfacial recombination process and photovoltage has functional relationship with defect density of perovskite absorption layer. A novel contour mapping method to understand the characteristics of current density-voltage (J-V) curves for each device as a function of perovskite layer thickness provide an important insight about the distribution spectrum of photovoltaic properties. Functional relationship of device efficiency and fill factor with absorption layer thickness are also discussed.
Kerboua, Kaouther; Hamdaoui, Oualid
2018-01-01
Based on two different assumptions regarding the equation describing the state of the gases within an acoustic cavitation bubble, this paper studies the sonochemical production of hydrogen, through two numerical models treating the evolution of a chemical mechanism within a single bubble saturated with oxygen during an oscillation cycle in water. The first approach is built on an ideal gas model, while the second one is founded on Van der Waals equation, and the main objective was to analyze the effect of the considered state equation on the ultrasonic hydrogen production retrieved by simulation under various operating conditions. The obtained results show that even when the second approach gives higher values of temperature, pressure and total free radicals production, yield of hydrogen does not follow the same trend. When comparing the results released by both models regarding hydrogen production, it was noticed that the ratio of the molar amount of hydrogen is frequency and acoustic amplitude dependent. The use of Van der Waals equation leads to higher quantities of hydrogen under low acoustic amplitude and high frequencies, while employing ideal gas law based model gains the upper hand regarding hydrogen production at low frequencies and high acoustic amplitudes. Copyright © 2017 Elsevier B.V. All rights reserved.
Chen, Xiaoyue; Lan, Lei; Lu, Hailiang; Wang, Yu; Wen, Xishan; Du, Xinyu; He, Wangling
2017-10-01
A numerical simulation method of negative direct current (DC) corona discharge based on a plasma chemical model is presented, and a coaxial cylindrical gap is adopted. There were 15 particle species and 61 kinds of collision reactions electrons involved, and 22 kinds of reactions between ions are considered in plasma chemical reactions. Based on this method, continuous Trichel pulses are calculated on about a 100 us timescale, and microcosmic physicochemical process of negative DC corona discharge in three different periods is discussed. The obtained results show that the amplitude of Trichel pulses is between 1-2 mA, and that pulse interval is in the order of 10-5 s. The positive ions produced by avalanche ionization enhanced the electric field near the cathode at the beginning of the pulse, then disappeared from the surface of cathode. The electric field decreases and the pulse ceases to develop. The negative ions produced by attachment slowly move away from the cathode, and the electric field increases gradually until the next pulse begins to develop. The positive and negative ions with the highest density during the corona discharge process are O4+ and O3- , respectively.
A Net Energy-based Analysis for a Climate-constrained Sustainable Energy Transition
Sgouridis, Sgouris; Csala, Denes
2015-01-01
The transition from a fossil-based energy economy to one based on renewable energy is driven by the double challenge of climate change and resource depletion. Building a renewable energy infrastructure requires an upfront energy investment that subtracts from the net energy available to society. This investment is determined by the need to transition to renewable energy fast enough to stave off the worst consequences of climate change and, at the same time, maintain a sufficient net energy flow to sustain the world's economy and population. We show that a feasible transition pathway requires that the rate of investment in renewable energy should accelerate approximately by an order of magnitude if we are to stay within the range of IPCC recommendations.
Zhang, X.; Anagnostou, E. N.; Nikolopoulos, E. I.; Bartsotas, N. S.
2015-12-01
Floods constitute one of the most significant and frequent natural hazard in mountainous regions. Satellite-based precipitation products offer in many cases the only available source of QPE. However, satellite-based QPE over complex terrain suffer from significant bias that limits their applicability for hydrologic modeling. In this work we investigate the potential of a new correction procedure, which involves the use of high-resolution numerical weather prediction (NWP) model simulations to adjust satellite QPE. Adjustment is based on the pdf matching of satellite and NWP (used as reference) precipitation distribution. The impact of correction procedure on simulating the hydrologic response is examined for 15 storm events that generated floods over the mountainous Upper Adige region of Northern Italy. Atmospheric simulations were performed at 1-km resolution from a state-of-the-art atmospheric model (RAMS/ICLAMS). The proposed error correction procedure was then applied on the widely used TRMM 3B42 satellite precipitation product and the evaluation of the correction was based on independent in situ precipitation measurements from a dense rain gauge network (1 gauge / 70 km2) available in the study area. Satellite QPE, before and after correction, are used to simulate flood response using ARFFS (Adige River Flood Forecasting System), a semi-distributed hydrologic model, which is used for operational flood forecasting in the region. Results showed that bias in satellite QPE before correction was significant and had a tremendous impact on the simulation of flood peak, however the correction procedure was able to reduce bias in QPE and therefore improve considerably the simulated flood hydrograph.
Directory of Open Access Journals (Sweden)
Basuki Widodo
2012-02-01
Full Text Available Corrosion process is a natural case that happened at the various metals, where the corrosion process in electrochemical can be explained by using galvanic cell. The iron corrosion process is based on the acidity degree (pH of a condensation, iron concentration and condensation temperature of electrolyte. Those are applied at electrochemistry cell. The iron corrosion process at this electrochemical cell also able to generate electrical potential and electric current during the process takes place. This paper considers how to build a mathematical model of iron corrosion, electrical potential and electric current. The mathematical model further is solved using the finite element method. This iron corrosion model is built based on the iron concentration, condensation temperature, and iteration time applied. In the electric current density model, the current based on electric current that is happened at cathode and anode pole and the iteration time applied. Whereas on the potential electric model, it is based on the beginning of electric potential and the iteration time applied. The numerical results show that the part of iron metal, that is gristle caused by corrosion, is the part of metal that has function as anode and it has some influences, such as time depth difference, iron concentration and condensation temperature on the iron corrosion process and the sum of reduced mass during corrosion process. Moreover, difference influence of time and beginning electric potential has an effect on the electric potential, which emerges during corrosion process at the electrochemical cell. Whereas, at the electrical current is also influenced by difference of depth time and condensation temperature applied.Keywords: Iron Corrosion, Concentration of iron, Electrochemical Cell and Finite Element Method
Research the key techniques based on the energy internet system
Wang, Xinlu
2017-08-01
In recent years, global climate change problem are increasingly deepen. The limited proved reserves of fossil fuels like oil is on the decrease each year, but the price is raised each year. Energy industry will have enormous changes. The people was inspired by the internet has achieved a great success, Energy Internet System (EIS) was proposed. EIS is considered to be a platform of the based on energy. This paper introduces energy router which is the core of Energy Internet System, and expound some function concepts. The core of the energy router is Solid State Transformer (SST), this paper sets out the core principles and some material questions like SiC semiconductor.
Energy monitoring system based on human activity in the workplace
Mustafa, Nur Hanim; Husain, Mohd Nor; Aziz, Mohamad Zoinol Abidin Abdul; Othman, Mohd Azlishah; Malek, Fareq
2015-05-01
Human behaviors always related to day routine activities in a smart house directly give the significant factor to manage energy usage in human life. An Addition that, the factor will contribute to the best efficiency of the system. This paper will focus on the monitoring efficiency based on duration time in office hours around 8am until 5pm which depend on human behavior at working place. Besides that, the correlation coefficient method is used to show the relation between energy consumption and energy saving based on the total hours of time energy spent. In future, the percentages of energy monitoring system usage will be increase to manage energy saving based on human behaviors. This scenario will help to see the human activity in the workplace in order to get the energy saving and support world green environment.
Fumin Ma; Gregory M. P. O’Hare; Tengfei Zhang; Michael J. O’Grady
2015-01-01
Conventional historical data based material and energy balance analyses are static and isolated computations. Such methods cannot embody the cross-coupling effect of energy flow, material flow and information flow in the process industry; furthermore, they cannot easily realize the effective evaluation and comparison of different energy transfer processes by alternating the model module. In this paper, a novel method for material balance and energy conservation analysis of process industry en...
A Web Based Puzzle for Energy Sources
Secken, Nilgun
2006-01-01
At present many countries in the world consume too much fossil fuels such as petroleum, natural gas and coal to meet their energy needs. These fossil fuels are not renewable; their sources are limited and reducing gradually. More importantly they have been becoming more expensive day by day and their damage to the environment has been increasing.…
Energy Technology Data Exchange (ETDEWEB)
Madrid, Rafael de la, E-mail: rafael.delamadrid@lamar.edu
2017-06-15
We express the resonant energies of the delta-shell potential in terms of the Lambert W function, and we calculate their decay widths and decay constants. The ensuing numerical results strengthen the interpretation of such decay widths and constants as a way to quantify the coupling between a resonance and the continuum. We calculate explicitly the decay energy spectrum of the resonances of the delta-shell potential, and we show numerically that the lineshape of such spectrum is not the same as, and can be very different from, the Breit–Wigner (Lorentzian) distribution. We argue that the standard Golden Rule cannot describe the interference of two resonances, and we show how to describe such interference by way of the decay energy spectrum of two resonant states.
de la Madrid, Rafael
2017-06-01
We express the resonant energies of the delta-shell potential in terms of the Lambert W function, and we calculate their decay widths and decay constants. The ensuing numerical results strengthen the interpretation of such decay widths and constants as a way to quantify the coupling between a resonance and the continuum. We calculate explicitly the decay energy spectrum of the resonances of the delta-shell potential, and we show numerically that the lineshape of such spectrum is not the same as, and can be very different from, the Breit-Wigner (Lorentzian) distribution. We argue that the standard Golden Rule cannot describe the interference of two resonances, and we show how to describe such interference by way of the decay energy spectrum of two resonant states.
Sliseris, J.; Yan, L.; Kasal, B.
2017-09-01
Numerical methods for simulating hollow and foam-filled flax-fabric-reinforced epoxy tubular energy absorbers subjected to lateral crashing are presented. The crashing characteristics, such as the progressive failure, load-displacement response, absorbed energy, peak load, and failure modes, of the tubes were simulated and calculated numerically. A 3D nonlinear finite-element model that allows for the plasticity of materials using an isotropic hardening model with strain rate dependence and failure is proposed. An explicit finite-element solver is used to address the lateral crashing of the tubes considering large displacements and strains, plasticity, and damage. The experimental nonlinear crashing load vs. displacement data are successfully described by using the finite-element model proposed. The simulated peak loads and absorbed energy of the tubes are also in good agreement with experimental results.
Directory of Open Access Journals (Sweden)
L Khadir
2016-10-01
Full Text Available The use of several developmental approaches is the researchers’ major preoccupation with the DARRIEUS wind turbine. This paper presents the first approach and results of a wide computational investigation on the aerodynamics of a vertical axis DARRIEUS wind turbine based on the MAGNUS effect. Consequently, wind tunnel tests were carried out to ascertain overall performance of the turbine and two-dimensional unsteady computational fluid dynamics (CFD models were generated to help understand the aerodynamics of this new performance. Accordingly, a moving mesh technique was used where the geometry of the turbine blade was cylinders. The turbine model was created in Gambit modeling software and then read into fluent software for fluid flow analysis. Flow field characteristics are investigated for several values of tip speed ratio (TSR, in this case we generated a new rotational speed ratio between the turbine and cylinder (δ = ωC/ωT. This new concept based on the MAGNUS approach provides the best configuration for better power coefficient values. The positive results of Cp obtained in this study are used to generate energy; on the other hand, the negative values of Cp could be used in order to supply the engines with energy.
Promoting Behavior-Based Energy Efficiency in Military Housing
Energy Technology Data Exchange (ETDEWEB)
AH McMakin; EL Malone; RE Lundgren
1999-09-07
The U.S. Department of Energy's Federal Energy Management Program (FEMP) helps agencies reduce the cost of doing business through energy efficiency, water conservation, and the use of solar and other renewable energy. As a large energy user, the U.S. military has been one of the government sectors of focus. Several military installations have shown substantial energy savings in past years. Most of these efficiency projects, however, have focused primarily on physical upgrades, technologies, and purchasing habits. Furthermost projects have focused on administrative and operational areas of energy use. Military residential housing, in particular, has received little formal attention for energy efficiency involving behaviors of the residents themselves. Behavior-based change is a challenging, but potentially fruitful area for energy conservation programs. However, behavioral change involves links with values, social networks and organizations, and new ways of thinking about living patterns. This handbook attempts to fill a gap by offering guidance for promoting such efforts.
Hu, R.; Liu, Q.
2016-12-01
For civil engineering projects, especially in the subsurface with groundwater, the artificial ground freezing (AGF) method has been widely used. Commonly, a refrigerant is circulated through a pre-buried pipe network to form a freezing wall to support the construction. In many cases, the temperature change is merely considered as a result of simple heat conduction. However, the influence of the water-ice phase change on the flow properties should not be neglected, if large amount of groundwater with high flow velocities is present. In this work, we perform a 2D modelling (software: Comsol Multiphysics) of an AFG project of a metro tunnel in Southern China, taking groundwater flow into account. The model is validated based on in-situ measurement of groundwater flow and temperature. We choose a cross section of this horizontal AGF project and set up a model with horizontal groundwater flow normal to the axial of the tunnel. The Darcy velocity is a coupling variable and related to the temperature field. During the phase change of the pore water and the decrement of permeability in freezing zone, we introduce a variable of effective hydraulic conductivity which is described by a function of temperature change. The energy conservation problem is solved by apparent heat capacity method and the related parameter change is described by a step function (McKenzie, et. al. 2007). The results of temperature contour maps combined with groundwater flow velocity at different times indicate that the freezing wall appears in an asymmetrical shape along the groundwater flow direction. It forms slowly and on the upstream side the thickness of the freezing wall is thinner than that on the downstream side. The closure time of the freezing wall increases at the middle of the both up and downstream sides. The average thickness of the freezing wall on the upstream side is mostly affected by the groundwater flow velocity. With the successful validation of this model, this numerical
Orbit determination based on meteor observations using numerical integration of equations of motion
Dmitriev, Vasily; Lupovka, Valery; Gritsevich, Maria
2015-11-01
Recently, there has been a worldwide proliferation of instruments and networks dedicated to observing meteors, including airborne and future space-based monitoring systems . There has been a corresponding rapid rise in high quality data accumulating annually. In this paper, we present a method embodied in the open-source software program "Meteor Toolkit", which can effectively and accurately process these data in an automated mode and discover the pre-impact orbit and possibly the origin or parent body of a meteoroid or asteroid. The required input parameters are the topocentric pre-atmospheric velocity vector and the coordinates of the atmospheric entry point of the meteoroid, i.e. the beginning point of visual path of a meteor, in an Earth centered-Earth fixed coordinate system, the International Terrestrial Reference Frame (ITRF). Our method is based on strict coordinate transformation from the ITRF to an inertial reference frame and on numerical integration of the equations of motion for a perturbed two-body problem. Basic accelerations perturbing a meteoroid's orbit and their influence on the orbital elements are also studied and demonstrated. Our method is then compared with several published studies that utilized variations of a traditional analytical technique, the zenith attraction method, which corrects for the direction of the meteor's trajectory and its apparent velocity due to Earth's gravity. We then demonstrate the proposed technique on new observational data obtained from the Finnish Fireball Network (FFN) as well as on simulated data. In addition, we propose a method of analysis of error propagation, based on general rule of covariance transformation.
Directory of Open Access Journals (Sweden)
Sebastian Kuboth
2017-02-01
Full Text Available Latent thermal energy storage (LTS systems are versatile due to their high-energy storage density within a small temperature range. In shell-and-tube type storage systems fins can be used in order to achieve enhanced charging and discharging power. Typically, circular fins are evenly distributed over the length of the heat exchanger pipe. However, it is yet to be proven that this allocation is the most suitable for every kind of system and application. Consequently, within this paper, a simulation model was developed in order to examine the effect of different fin distributions on the performance of shell-and-tube type latent thermal storage units at discharge. The model was set up in MATLAB Simulink R2015b (The MathWorks, Inc., Natick, MA, USA based on the enthalpy method and validated by a reference model designed in ANSYS Fluent 15.0 (ANSYS, Inc., Canonsburg, PA, USA. The fin density of the heat exchanger pipe was increased towards the pipe outlet. This concentration of fins was implemented linearly, exponentially or suddenly with the total number of fins remaining constant during the variation of fin allocations. Results show that there is an influence of fin allocation on storage performance. However, the average storage performance at total discharge only increased by three percent with the best allocation compared to an equidistant arrangement.
Smart and Green Energy (SAGE) for Base Camps Final Report
Energy Technology Data Exchange (ETDEWEB)
Engels, Matthias; Boyd, Paul A.; Koehler, Theresa M.; Goel, Supriya; Sisk, Daniel R.; Hatley, Darrel D.; Mendon, Vrushali V.; Hail, John C.
2014-02-11
The U.S. Army Logistics Innovation Agency’s (LIA’s) Smart and Green Energy (SAGE) for Base Camps project was to investigate how base camps’ fuel consumption can be reduced by 30% to 60% using commercial off-the-shelf (COTS) technologies for power generation, renewables, and energy efficient building systems. Field tests and calibrated energy models successfully demonstrated that the fuel reductions are achievable.
Energy Constraint Node Cache Based Routing Protocol For Adhoc Network
Dhiraj Nitnaware; Ajay Verma
2010-01-01
Mobile Adhoc Networks (MANETs) is a wireless infrastructureless network, where nodes are free to move independently in any direction. The nodes have limited battery power; hence we require energy efficient routing protocols to optimize network performance. This paper aims to develop a new routing algorithm based on the energy status of the node cache. We have named this algorithm as ECNC_AODV (Energy Constraint Node Cache) based routing protocol which is derived from the AODV protocol. The al...
Net Balanced Floorplanning Based on Elastic Energy Model
DEFF Research Database (Denmark)
Liu, Wei; Nannarelli, Alberto
2008-01-01
with balanced net delays to increase the safety margins of the design. In this paper, we investigate the properties of floorplanning based on the elastic energy model. The B*-tree, which is based on an ordered binary tree, is used for circuit representation and the elastic energy is used as the cost function...
Demand Side Management Using the Internet of Energy Based on LoRaWAN Technology
DEFF Research Database (Denmark)
Shahryari, Kolsoom; Anvari-Moghaddam, Amjad; Shahryari, Shadi
2017-01-01
The smart grid, as a communication network, allows numerous connected devices such as sensors, relays and actuators to interact and cooperate with each other. An Internet-based solution for electricity that provides bidirectional flow of information and power is internet of energy (IoE) which...... for scheduling devices/appliances by creating a priority queue which can perform demand side management dynamically. The queue is affected by not only the consumer importance but also the consumer policies and the status of energy resources....
DEFF Research Database (Denmark)
Parmeggiani, Stefano; Muliawan, Made Jaya; Gao, Zhen
2012-01-01
The Wave Dragon Wave Energy Converter is ready to be up-scaled to commercial size. The design and feasibility analysis of a 1.5 MW pre-commercial unit to be deployed at the DanWEC test center in Hanstholm, Denmark, is currently ongoing. With regard to the mooring system, the design has...... to be carried out numerically, through coupled analyses of alternative solutions. The present study deals with the preliminary hydrodynamic characterization of Wave Dragon needed in order to calibrate the numerical model to be used for the mooring design. A hydrodynamic analysis of the small scale model...
Kornet, Kacper
2014-01-01
We put forward a new type of spectral method for the direct numerical simulation of flows where anisotropy or very fine boundary layers are present. The mean idea is to take advantage of the fact that such structures are dissipative and that their presence should reduce the number of degrees of freedom of the flow, when paradoxically, their fine resolution incurs extra computational cost in most current methods. The principle of this method is to use a functional basis with elements that already include these fine structure so as to avoid these extra costs. This leads us to develop an algorithm to implement a spectral method for arbitrary functional bases, and in particular, non-orthogonal ones. We construct a basic implementation of this algorithm to simulate Magnetohydrodynamic (MHD) channel flows with an externally imposed, transverse magnetic field, where very thin boundary layers are known to develop along the channel walls. In this case, the sought functional basis can be built out of the eigenfunctions...
Cell light scattering characteristic numerical simulation research based on FDTD algorithm
Lin, Xiaogang; Wan, Nan; Zhu, Hao; Weng, Lingdong
2017-01-01
In this study, finite-difference time-domain (FDTD) algorithm has been used to work out the cell light scattering problem. Before beginning to do the simulation contrast, finding out the changes or the differences between normal cells and abnormal cells which may be cancerous or maldevelopment is necessary. The preparation of simulation are building up the simple cell model of cell which consists of organelles, nucleus and cytoplasm and setting up the suitable precision of mesh. Meanwhile, setting up the total field scattering field source as the excitation source and far field projection analysis group is also important. Every step need to be explained by the principles of mathematic such as the numerical dispersion, perfect matched layer boundary condition and near-far field extrapolation. The consequences of simulation indicated that the position of nucleus changed will increase the back scattering intensity and the significant difference on the peak value of scattering intensity may result from the changes of the size of cytoplasm. The study may help us find out the regulations based on the simulation consequences and the regulations can be meaningful for early diagnosis of cancers.
Energy Technology Data Exchange (ETDEWEB)
Mao, Jinlong; Zuo, Zhengxing; Li, Wen; Feng, Huihua [School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081 (China)
2011-04-15
A free-piston linear alternator (FPLA) is being developed by the Beijing Institute of Technology to improve the thermal efficiency relative to conventional crank-driven engines. A two-stroke scavenging process recharges the engine and is crucial to realizing the continuous operation of a free-piston engine. In order to study the FPLA scavenging process, the scavenging system was configured using computational fluid dynamics. As the piston dynamics of the FPLA are different to conventional crank-driven two-stroke engines, a time-based numerical simulation program was built using Matlab to define the piston's motion profiles. A wide range of design and operating options were investigated including effective stroke length, valve overlapping distance, operating frequency and charging pressure to find out their effects on the scavenging performance. The results indicate that a combination of high effective stroke length to bore ratio and long valve overlapping distance with a low supercharging pressure has the potential to achieve high scavenging and trapping efficiencies with low short-circuiting losses. (author)
Numerical flow models and their calibration using tracer based ages: Chapter 10
Sanford, W.
2013-01-01
Any estimate of ‘age’ of a groundwater sample based on environmental tracers requires some form of geochemical model to interpret the tracer chemistry (chapter 3) and is, therefore, referred to in this chapter as a tracer model age. the tracer model age of a groundwater sample can be useful for obtaining information on the residence time and replenishment rate of an aquifer system, but that type of data is most useful when it can be incorporated with all other information that is known about the groundwater system under study. groundwater fl ow models are constructed of aquifer systems because they are usually the best way of incorporating all of the known information about the system in the context of a mathematical framework that constrains the model to follow the known laws of physics and chemistry as they apply to groundwater flow and transport. It is important that the purpose or objective of the study be identified first before choosing the type and complexity of the model to be constructed, and to make sure such a model is necessary. The purpose of a modelling study is most often to characterize the system within a numerical framework, such that the hydrological responses of the system can be tested under potential stresses that might be imposed given future development scenarios. As this manual discusses dating as it applies to old groundwater, most readers are likely to be interested in studying regional groundwater flow systems and their water resource potential.
The human otitis media with effusion: a numerical-based study.
Areias, B; Parente, M P L; Santos, C; Gentil, F; Natal Jorge, R M
2017-07-01
Otitis media is a group of inflammatory diseases of the middle ear. Acute otitis media and otitis media with effusion (OME) are its two main types of manifestation. Otitis media is common in children and can result in structural alterations in the middle ear which will lead to hearing losses. This work studies the effects of an OME on the sound transmission from the external auditory meatus to the inner ear. The finite element method was applied on the present biomechanical study. The numerical model used in this work was built based on the geometrical information obtained from The visible ear project. The present work explains the mechanisms by which the presence of fluid in the middle ear affects hearing by calculating the magnitude, phase and reduction of the normalized umbo velocity and also the magnitude and phase of the normalized stapes velocity. A sound pressure level of 90 dB SPL was applied at the tympanic membrane. The harmonic analysis was performed with the auditory frequency varying from 100 Hz to 10 kHz. A decrease in the response of the normalized umbo and stapes velocity as the tympanic cavity was filled with fluid was obtained. The decrease was more accentuated at the umbo.
Seo, B. C.; Bradley, A.; Krajewski, W. F.
2015-12-01
The recent upgrade of dual-polarization with NEXRAD radars has assisted in improving the characterization of microphysical processes in precipitation and thus has enabled precipitation estimation based on the identified precipitation types. While this polarimetric capability promises the potential for the enhanced accuracy in quantitative precipitation estimation (QPE), recent studies show that the polarimetric estimates are still affected by uncertainties arising from the radar beam geometry/sampling space associated with the vertical variability of precipitation. The authors, first of all, focus on evaluating the NEXRAD hydrometeor classification product using ground reference data (e.g., ASOS) that provide simple categories of the observed precipitation types (e.g., rain, snow, and freezing rain). They also investigate classification uncertainty features caused by the variability of precipitation between the ground and the altitudes where radar samples. Since this variability is closely related to the atmospheric conditions (e.g., temperature) at near surface, useful information (e.g., critical thickness and temperature profile) that is not available in radar observations is retrieved from the numerical weather prediction (NWP) model data such as Rapid Refresh (RAP)/High Resolution Rapid Refresh (HRRR). The NWP retrieved information and polarimetric radar data are used together to improve the accuracy of precipitation type identification at near surface. The authors highlight major improvements and discuss limitations in the real-time application.
High Numerical Aperture Hexagonal Stacked Ring-Based Bidirectional Flexible Polymer Microlens Array.
Ahmed, Rajib; Yetisen, Ali K; Butt, Haider
2017-03-28
Flexible imprinted photonic nanostructures that are able to diffract/focus narrow-band light have potential applications in optical lenses, filters, tunable lasers, displays, and biosensing. Nanophotonic structures through holography and roll-to-roll printing may reduce fabrication complexities and expenses and enable mass production. Here, 3D photonic nanostructures of a stacked ring array were imprinted on acrylate polymer (AP) over poly(ethylene terephthalate) (PET) substrate through holography and lift-off processes to create a microlens array (MLA). The surface structure of the array consisted of circular nonostepped pyramids, and repeated patterns were in hexagonal arrangements. Stacked-ring-based MLA (SMLA) on a flexible AP-PET substrate showed efficient bidirectional light focusing and maximum numerical aperture (NA = 0.60) with a reasonable filling factor. The nanostructures produced a well-ordered hexagonally focused diffraction pattern in the far field, and power intensities were measured through angle-resolved experiments. The variation of nanostep dimensions (width and height) and the number of steps resulted in different photonic bandgaps, and the arrays produced distance-dependent narrow-band light focusing. The validation of the SMLA was demonstrated through the text, image, and hologram projection experiments. It is anticipated that imprinted bidirectional SMLA over flexible substrates may find applications in optical systems, displays, and portable sensors.
Generating Irregular Models for 3D Spherical-Particle-Based Numerical Methods
Directory of Open Access Journals (Sweden)
Gang-Hai Huang
2013-01-01
Full Text Available The realistic representation of an irregular geological body is essential to the construction of a particle simulation model. A three-dimensional (3D sphere generator for an irregular model (SGIM, which is based on the platform of Microsoft Foundation Classes (MFC in VC++, is developed to accurately simulate the inherent discontinuities in geological bodies. OpenGL is employed to visualize the modeling in the SGIM. Three key functions, namely, the basic-model-setup function, the excavating function, and the cutting function, are implemented. An open-pit slope is simulated using the proposed model. The results demonstrate that an extremely irregular 3D model of a geological body can be generated using the SGIM and that various types of discontinuities can be inserted to cut the model. The data structure of the model that is generated by the SGIM is versatile and can be easily modified to match various numerical calculation tools. This can be helpful in the application of particle simulation methods to large-scale geoengineering projects.
Directory of Open Access Journals (Sweden)
Fumin Ma
2015-10-01
Full Text Available Conventional historical data based material and energy balance analyses are static and isolated computations. Such methods cannot embody the cross-coupling effect of energy flow, material flow and information flow in the process industry; furthermore, they cannot easily realize the effective evaluation and comparison of different energy transfer processes by alternating the model module. In this paper, a novel method for material balance and energy conservation analysis of process industry energy transfer system is developed based on model property. Firstly, a reconfigurable energy transfer process model, which is independent of energy types and energy-consuming equipment, is presented from the viewpoint of the cross-coupling effect of energy flow, material flow and information flow. Thereafter the material balance determination is proposed based on both a dynamic incidence matrix and dynamic balance quantity. Moreover, the model-weighted conservation determination theorem is proved, and the energy efficiency analysis method is also discussed. Results confirmed the efficacy of the proposed methods, confirming its potential for use by process industry in energy efficiency analyses.
Numerical analysis of thermo-hydro-mechanical (THM) processes in the clay based material
Energy Technology Data Exchange (ETDEWEB)
Wang, Xuerui
2016-10-06
Clay formations are investigated worldwide as potential host rock for the deep geological disposal of high-level radioactive waste (HLW). Usually bentonite is preferred as the buffer and backfill material in the disposal system. In the disposal of HLW, heat emission is one of the most important issues as it can generate a series of complex thermo-hydro-mechanical (THM) processes in the surrounding materials and thus change the material properties. In the context of safety assessment, it is important to understand the thermally induced THM interactions and the associated change in material properties. In this work, the thermally induced coupled THM behaviours in the clay host rock and in the bentonite buffer as well as the corresponding coupling effects among the relevant material properties are numerically analysed. A coupled non-isothermal Richards flow mechanical model and a non-isothermal multiphase flow model were developed based on the scientific computer codes OpenGeoSys (OGS). Heat transfer in the porous media is governed by thermal conduction and advective flow of the pore fluids. Within the hydraulic processes, evaporation, vapour diffusion, and the unsaturated flow field are considered. Darcy's law is used to describe the advective flux of gas and liquid phases. The relative permeability of each phase is considered. The elastic deformation process is modelled by the generalized Hooke's law complemented with additional strain caused by swelling/shrinkage behaviour and by temperature change. In this study, special attention has been paid to the analysis of the thermally induced changes in material properties. The strong mechanical and hydraulic anisotropic properties of clay rock are described by a transversely isotropic mechanical model and by a transversely isotropic permeability tensor, respectively. The thermal anisotropy is described by adoption of the bedding-orientation-dependent thermal conductivity. The dependency of the thermal
Sea wave energy based in nanotechnology
Energy Technology Data Exchange (ETDEWEB)
Duque, Carlos
2010-09-15
Application on which it turns east document is the recovery of the energy of the sea waves turning it into electricity by means of the combination of nano-piezoelectric and condensing, the system would be seen like a compound floating fabric of million piezoelectric crystals that turn the oscillating movement of the sea into micro-electrical signals that they are added and they left by means cables to the surface where electronics devices classified to the load of condensers, from the electricity is confined and later is invested and synchronize itself with the great national mains.
Energy-based control for a biologically inspired hexapod robot with rolling locomotion
Directory of Open Access Journals (Sweden)
Takuma Nemoto
2015-04-01
Full Text Available This paper presents an approach to control rolling locomotion on the level ground with a biologically inspired hexapod robot. For controlling rolling locomotion, a controller which can compensate energy loss with rolling locomotion of the hexapod robot is designed based on its dynamic model. The dynamic model describes the rolling locomotion which is limited to planar one by an assumption that the hexapod robot does not fall down while rolling and influences due to collision and contact with the ground, and it is applied for computing the mechanical energy of the hexapod robot and a plant for a numerical simulation. The numerical simulation of the rolling locomotion on the level ground verifies the effectiveness of the proposed controller. The simulation results show that the hexapod robot can perform the rolling locomotion with the proposed controller. In conclusion, it is shown that the proposed control approach is effective in achieving the rolling locomotion on the level ground.
AN EOS-BASED NUMERICAL SIMULATION OF THERMAL RECOVERY PROCESS USING UNSTRUCTURED MESHES
Directory of Open Access Journals (Sweden)
F. Marcondes
2015-03-01
Full Text Available Abstract In the past thirty years, the development of compositional reservoir simulators using an equation of state (EOS has been addressed in the literature. However, the development of compositional thermal simulators in conjunction with the EOS formulation, in particular, has not been addressed extensively. In this work, a fully implicit, thermal, compositional EOS-based simulator in conjunction with unstructured meshes has been developed. In this model, an equation of state is used for equilibrium calculations among phases. Also, the physical properties are calculated based on an EOS, hence obviating the need for using steam tables for calculation of water/steam properties. The governing equations for the model comprise fugacity equations, material balance, pore volume constraint and energy equation. The governing partial differential equations are solved using the EbFVM (Element based Finite Volume Method. Results for several case studies consisting of 2D and 3D reservoirs are presented in order to demonstrate the applicability of the method.
Net-Zero Energy Buildings: A Classification System Based on Renewable Energy Supply Options
Energy Technology Data Exchange (ETDEWEB)
Pless, S.; Torcellini, P.
2010-06-01
A net-zero energy building (NZEB) is a residential or commercial building with greatly reduced energy needs. In such a building, efficiency gains have been made such that the balance of energy needs can be supplied with renewable energy technologies. Past work has developed a common NZEB definition system, consisting of four well-documented definitions, to improve the understanding of what net-zero energy means. For this paper, we created a classification system for NZEBs based on the renewable sources a building uses.
Song, Youn Kyung; Figlus, Jens; Chardón-Maldonado, Patricia; Puleo, Jack A.
2017-04-01
The inner surf/swash zone of a coastal beach is characterized as an intermittently wet and dry zone in the nearshore that often develops a variety of morphological features including intertidal bars and ridge-runnel (RR) systems. The cross-shore morphodynamic numerical model CSHORE is used to simulate the beach recovery observed during a field experiment carried out at South Bethany Beach, Delaware, a nourished, high-gradient meso-tidal sandy beach along the U. S. Coast. The field campaign was conducted from February 12 to February 25, 2014 to measure bed profile morphology change and sediment characteristics along with detailed hydrodynamic forcing parameters at six cross-shore stations, closely spaced over approximately 50 m in the inner surf and swash zone. On February 13, 2014 a Nor'easter eroded significant portions of the beach leading to formation of a pronounced RR system on the beach face that subsequently accreted in the recovery process after the storm. Bed profile changes, surf and swash velocity profiles, water free surface elevation and suspended sediment concentrations recorded during the recovery at the cross-shore measuring locations on the seaward face of the accreting ridge are compared with CSHORE simulation results. During post-storm recovery, CSHORE demonstrates shoreward migration of the ridge and slight accretion on the beach face by the end of the simulation period on February 25, 2014. This trend was also observed in the field, where accretion at the ridge crest was up to 1.0 m with respect to the post-storm profile. The CSHORE parameters critical to improving model performance in reproducing measured morphodynamics and hydrodynamics during the ridge accretion process are examined and calibrated. Initial results show promise in using this type of efficient, process-based model to reproduce morphological evolution and depth-averaged hydrodynamics as a result of the complex surf and swash zone dynamics associated with beach accretion and RR
Recent Progress on PZT Based Piezoelectric Energy Harvesting Technologies
Directory of Open Access Journals (Sweden)
Min-Gyu Kang
2016-02-01
Full Text Available Energy harvesting is the most effective way to respond to the energy shortage and to produce sustainable power sources from the surrounding environment. The energy harvesting technology enables scavenging electrical energy from wasted energy sources, which always exist everywhere, such as in heat, fluids, vibrations, etc. In particular, piezoelectric energy harvesting, which uses a direct energy conversion from vibrations and mechanical deformation to the electrical energy, is a promising technique to supply power sources in unattended electronic devices, wireless sensor nodes, micro-electronic devices, etc., since it has higher energy conversion efficiency and a simple structure. Up to now, various technologies, such as advanced materials, micro- and macro-mechanics, and electric circuit design, have been investigated and emerged to improve performance and conversion efficiency of the piezoelectric energy harvesters. In this paper, we focus on recent progress of piezoelectric energy harvesting technologies based on PbZrxTi1-xO3 (PZT materials, which have the most outstanding piezoelectric properties. The advanced piezoelectric energy harvesting technologies included materials, fabrications, unique designs, and properties are introduced to understand current technical levels and suggest the future directions of piezoelectric energy harvesting.
Management of a power system based on renewable energy
Directory of Open Access Journals (Sweden)
Ronay Karoly
2012-06-01
Full Text Available This article main purpose is to highlight the main advantage of the hardware and software implementation for an energy management system based on renewable energy sources. By using implemented and dedicated hardware and software the evolution of energy production and consumption can be monitored. The advantages of such system are highlighted by the results obtained from experimental simulations. An experimental model for the power system based on renewable energy sources was implemented, where the actual status of the system in different situations when the equipments change their own statuses can be shown.
Numerical model of frequency converter based on four-wave mixing in semiconductor amplifiers
DEFF Research Database (Denmark)
Cassioli, D.; Scotti, S.; Mecozzi, A.
1999-01-01
We describe a numerical model of the dynamics of a semiconductor optical amplifier that includes the description of the nonlinear optical processes within the waveguide and the longitudinal inhomogeneity caused by the saturating field.......We describe a numerical model of the dynamics of a semiconductor optical amplifier that includes the description of the nonlinear optical processes within the waveguide and the longitudinal inhomogeneity caused by the saturating field....
An Adjoint-based Numerical Method for a class of nonlinear Fokker-Planck Equations
Festa, Adriano
2017-03-22
Here, we introduce a numerical approach for a class of Fokker-Planck (FP) equations. These equations are the adjoint of the linearization of Hamilton-Jacobi (HJ) equations. Using this structure, we show how to transfer the properties of schemes for HJ equations to the FP equations. Hence, we get numerical schemes with desirable features such as positivity and mass-preservation. We illustrate this approach in examples that include mean-field games and a crowd motion model.
Baseline of numerical simulations for ZnTe based thin-film solar cells.
Ullah, Hanif; Ullah, Shafi; Marí, B.
2016-01-01
Abstract Numerical modelling of photovoltaic solar cells is an important strategy to test the viability of proposed physical structures and their performance. This article introduces the concept of numerical simulation and explain the relevant physical models for the inside physical phenomenon like generation, recombination and transport of charge carriers (holes and electrons) in photovoltaic materials. This will made with essential input parameters, to have consistent and acceptable res...
Timonin, A. M.
2016-09-01
Based on the finite-layer method, a method for evaluating the stress-strain state and energy release rate for specimens with delaminations in double-cantilever beam and end-notched flexure tests is proposed. Exact numerical solutions of boundary-value problems for the "stiff" systems of differential equations describing deformations of test specimens are obtained. The distributions of forces, moments, displacements, and rotations in the specimens and the distributions of normal and tangential stresses on their midline are presented. New closed-form expressions for these functions and for compliance of the specimens are developed. Calculation results for the energy release rate obtained by a numerical differentiation and from analytical relations are presented. Two new techniques for estimating the energy release rate are proposed: (1) using the calculated values of peak stress and jumps of displacements at the tip of delamination; (2) by evaluation of indeterminacy at the tip of delamination with the use of stresses and derivatives of stresses and displacements. The effect of the transverse shear and Poisson ratio on the results is estimated. A comparison of the numerical and analytical solutions obtained with known results and the ASTM standard is presented.
MEMS based pyroelectric thermal energy harvester
Hunter, Scott R; Datskos, Panagiotis G
2013-08-27
A pyroelectric thermal energy harvesting apparatus for generating an electric current includes a cantilevered layered pyroelectric capacitor extending between a first surface and a second surface, where the first surface includes a temperature difference from the second surface. The layered pyroelectric capacitor includes a conductive, bimetal top electrode layer, an intermediate pyroelectric dielectric layer and a conductive bottom electrode layer. In addition, a pair of proof masses is affixed at a distal end of the layered pyroelectric capacitor to face the first surface and the second surface, wherein the proof masses oscillate between the first surface and the second surface such that a pyroelectric current is generated in the pyroelectric capacitor due to temperature cycling when the proof masses alternately contact the first surface and the second surface.
The spatiotempora variations rules of Songzao coal mining subsidence based on numerical simulation
Lu, J.; Li, Y.; Cheng, H.; Tang, Z.
2015-11-01
With the increasing demand of coal, coal mining at Songzao makes the area of land subsidence growing larger. Land subsidence in coal mining area not only made large subsided farmland out of production and caused the enormous loss to local agricultural production, but also brought a number of serious problems to the local social economy and ecology Environment. To use Probability-integral Method based on numerical simulation of Songzao Mine, its subsidence simulation data from 1999 to 2009 was obtained. Hence, overlay analysis between Goaf data and the simulation data in 2009, and between field investigation and the simulation data in 2009 were carried out. After the coal mining underground was identified as the crucial cause of surface subsidence. Therefore, the accuracy and feasibility of the simulation data had been verified, and the spatial pattern and spatiotemporal variations conforming to the actual values have been obtained. The results show five main findings. The first indicated that the surface subsidence is mostly located at the top of the Goaf, where the overlap areas between Goaf data and subsidence simulation data have accounted for 93.05 % of Goaf and 65.19 % of subsidence simulation data respectively. The second finding indicated that by end of 2009, the mining subsidence extent had reached about 5087.50 hm2. This area accounts for about 40 % of total of the mining area. The third finding indicated that within 10 years from 1999 to 2009, the influence range of subsidence has expanded about 2340.54 hm2, and the coal mining subsidence rate in Songzao Mine has increased gradually with time. Moreover, average increasing speed of the extent area in the second five years was larger than the first five years (about 75.08 hm2 yr-1 more). The fourth finding indicated that maximum subsidence has increased from 2.0 m in 1999 to 2.5 m in 2004, and then 3.0m in 2009 with subsidence rate of about 0.1 m yr-1. At the same time, the area affected by the subsidence 2
The spatiotempora variations rules of Songzao coal mining subsidence based on numerical simulation
Directory of Open Access Journals (Sweden)
J. Lu
2015-11-01
Full Text Available With the increasing demand of coal, coal mining at Songzao makes the area of land subsidence growing larger. Land subsidence in coal mining area not only made large subsided farmland out of production and caused the enormous loss to local agricultural production, but also brought a number of serious problems to the local social economy and ecology Environment. To use Probability-integral Method based on numerical simulation of Songzao Mine, its subsidence simulation data from 1999 to 2009 was obtained. Hence, overlay analysis between Goaf data and the simulation data in 2009, and between field investigation and the simulation data in 2009 were carried out. After the coal mining underground was identified as the crucial cause of surface subsidence. Therefore, the accuracy and feasibility of the simulation data had been verified, and the spatial pattern and spatiotemporal variations conforming to the actual values have been obtained. The results show five main findings. The first indicated that the surface subsidence is mostly located at the top of the Goaf, where the overlap areas between Goaf data and subsidence simulation data have accounted for 93.05 % of Goaf and 65.19 % of subsidence simulation data respectively. The second finding indicated that by end of 2009, the mining subsidence extent had reached about 5087.50 hm2. This area accounts for about 40 % of total of the mining area. The third finding indicated that within 10 years from 1999 to 2009, the influence range of subsidence has expanded about 2340.54 hm2, and the coal mining subsidence rate in Songzao Mine has increased gradually with time. Moreover, average increasing speed of the extent area in the second five years was larger than the first five years (about 75.08 hm2 yr−1 more. The fourth finding indicated that maximum subsidence has increased from 2.0 m in 1999 to 2.5 m in 2004, and then 3.0m in 2009 with subsidence rate of about 0.1 m yr−1. At the same time, the area
Building a Pre-Competitive Knowledge Base to Support Australia's Wave Energy Industry
Hoeke, R. K.; Hemer, M. A.; Symonds, G.; Rosebrock, U.; Kenyon, R.; Zieger, S.; Durrant, T.; Contardo, S.; O'Grady, J.; Mcinnes, K. L.
2016-02-01
A pre-competitive, query-able and openly available spatio-temporal atlas of Australia's wind-wave energy resource and marine management uses is being delivered. To provide the best representation of wave energy resource information, accounting for both spatial and temporal characteristics of the resource, a 34+yr numerical hindcast of wave conditions in the Australian region has been developed. Considerable in situ and remotely sensed data have been collected to support calibration and validation of the hindcast, resulting in a high-quality characterisation of the available wave resource in the Australian domain. Planning for wave energy projects is also subject to other spatial constraints. Spatial information on alternative uses of the marine domain including, for example, fisheries and aquaculture, oil and gas, shipping, navigation and ports, marine parks and reserves, sub-sea cables and infrastructure, shipwrecks and sites of cultural significance, have been compiled to complement the spatial characterisation of resource and support spatial planning of future wave energy projects. Both resource and spatial constraint information are being disseminated via a state-of-the-art portal, designed to meet the needs of all industry stakeholders. Another aspect currently impeding the industry in Australia is the limited evidence-base of impacts of wave energy extraction on adjacent marine and coastal environments. To build this evidence base, a network of in situ wave measurement devices have been deployed surrounding the 3 wave energy converters of Carnegie Wave Energy Limited's Perth Wave Energy Project. This data is being used to calibrate and validate numerical simulations of the project site. Early stage results will be presented.
Fleming, K K; Longmire, E K; Hubel, A
2007-10-01
Cells are routinely cryopreserved in dimethyl sulfoxide (DMSO), a cryoprotective agent, for medical applications. Infusion of a DMSO-laden cell suspension results in adverse patient reactions, but current DMSO extraction processes result in significant cell losses. A diffusion-based numerical model was employed to characterize DMSO extraction in fully developed channel flow containing a wash stream flowing parallel to a DMSO-laden cell suspension. DMSO was allowed to diffuse across cell membranes as well as across the channel depth. A variety of cases were considered with the ultimate goal of characterizing the optimal geometry and flow conditions to process clinical volumes of cell suspension in a reasonable time (2-3 ml/min). The results were dependent on four dimensionless parameters: depth fraction of the DMSO-laden stream, Peclet number, cell volume fraction in the DMSO-laden stream, and cell membrane permeability parameter. Smaller depth fractions led to faster DMSO extraction but channel widths that were not practical. Higher Peclet numbers led to longer channels but smaller widths. For the Peclet values and channel depths considered (>or=500 microm) and appropriate permeability values, diffusion across cell membranes was significantly faster than diffusion across the channel depth. Cell volume fraction influenced the cross-stream diffusion of DMSO by limiting the fluid volume fraction available in the contaminant stream but did not play a significant role in channel geometry or operating requirements. The model was validated against preliminary experiments in which DMSO was extracted from suspensions of B-lymphoblast cells. The model results suggest that a channel device with practical dimensions can remove a sufficient level of contaminant within a mesoscale volume of cells in the required time.
Assesment of SIRGAS Ionospheric Maps errors based on a numerical simulation
Brunini, Claudio; Emilio, Camilion; Francisco, Azpilicueta
2010-05-01
SIRGAS (Sistema de Referencia Geocéntrico para las Américas) is responsible of the International Terrestrial Reference Frame densification in Latin America and the Caribbean, which is realized and maintained by means of a continuously operational GNSS network with more than 200 receivers. Besides, SIRGAS uses this network for computing regional maps of the vertical Total Electron Content (TEC), which are released to the community through the SIRGAS web page (www.sirgas.org). As other similar products (e.g.: Global Ionospheric Maps (GIM) computed by the International GNSS Service), SIRGAS Ionospheric Maps (SIM) are based on a thin layer ionospheric model, in which the whole ionosphere is represented by one spherical layer of infinitesimal thickness and equivalent vertical TEC, located at a fixed height above the Earth's surface (tipycally between 350 and 450 km). This contribution aims to characterize the errors introduced in the thin layer ionospheric model by the use of a fixed and, sometimes, inappropiated ionospheric layer height. Particular attention is payed to the propagation of these errors to the estimation of the vertical TEC and to the estimation of the GNSS satellites and receivers Inter-Frequency Biases (IFB). The work relies upon a numerical simulation performed with an empirical model of the Earth's ionosphere, which allows creating a realistic but controlled ionospheric scenario, and then evaluates the errors that are produced when the thin layer model is used to reproduce those ionospheric scenarios. The error assessment is performed for the Central and the northern part of the South American continents, where largest errors are expected because the combined actions of the Appleton Anomaly of the ionosphere and the South-Atlantic anomaly of the geomagnetic field.
Numerical simulation on ferrofluid flow in fractured porous media based on discrete-fracture model
Huang, Tao; Yao, Jun; Huang, Zhaoqin; Yin, Xiaolong; Xie, Haojun; Zhang, Jianguang
2017-06-01
Water flooding is an efficient approach to maintain reservoir pressure and has been widely used to enhance oil recovery. However, preferential water pathways such as fractures can significantly decrease the sweep efficiency. Therefore, the utilization ratio of injected water is seriously affected. How to develop new flooding technology to further improve the oil recovery in this situation is a pressing problem. For the past few years, controllable ferrofluid has caused the extensive concern in oil industry as a new functional material. In the presence of a gradient in the magnetic field strength, a magnetic body force is produced on the ferrofluid so that the attractive magnetic forces allow the ferrofluid to be manipulated to flow in any desired direction through the control of the external magnetic field. In view of these properties, the potential application of using the ferrofluid as a new kind of displacing fluid for flooding in fractured porous media is been studied in this paper for the first time. Considering the physical process of the mobilization of ferrofluid through porous media by arrangement of strong external magnetic fields, the magnetic body force was introduced into the Darcy equation and deals with fractures based on the discrete-fracture model. The fully implicit finite volume method is used to solve mathematical model and the validity and accuracy of numerical simulation, which is demonstrated through an experiment with ferrofluid flowing in a single fractured oil-saturated sand in a 2-D horizontal cell. At last, the water flooding and ferrofluid flooding in a complex fractured porous media have been studied. The results showed that the ferrofluid can be manipulated to flow in desired direction through control of the external magnetic field, so that using ferrofluid for flooding can raise the scope of the whole displacement. As a consequence, the oil recovery has been greatly improved in comparison to water flooding. Thus, the ferrofluid
Numerical study of ball behavior in side-foot soccer kick based on impact dynamic theory.
Ishii, Hideyuki; Yanagiya, Toshio; Naito, Hisashi; Katamoto, Shizuo; Maruyama, Takeo
2009-12-11
This study examined the factors affecting the ball velocity and rotation for side-foot soccer kick using a numerical investigation. Five experienced male university soccer players performed side-foot kicks with various attack angles and impact points using a one-step approach. The kicking motions were captured three-dimensionally by two high-speed cameras at 2500 fps. The theoretical equations of the ball velocity and rotation were derived based on impact dynamic theory. Using the theoretical equations, the relationships of the ball velocity and rotation to the attack angle and impact point were obtained. The validity of the theoretical equations was verified by comparing the theoretical relationships with measurement values. Furthermore, simulations of the ball velocity and rotation were conducted using the theoretical equations. The theoretical relationships were in good agreement with the measurement values. The theoretical results confirmed the previously reported experimental results, and indicated that the impact point is more influential on the ball velocity than the attack angle and the attack angle is more influential on the ball rotation than the impact point. The simulation results indicated the following. The ball velocity produced by impact for all impact patterns is largely affected by the foot velocity immediately before impact but barely affected by the degree of slip between the foot and the ball. The ball rotation produced by an impact with a large attack angle is affected by the foot velocity immediately before impact and the degree of slip between the foot and the ball; however, these factors affect the ball rotation less than the attack angle.
A numerical study of multi filament formation in metal-ion based CBRAM
Directory of Open Access Journals (Sweden)
Dan Berco
2016-02-01
Full Text Available This study investigates the underlying mechanisms of multiple conductive filaments (CF creation in metal-ion based conductive bridge RRAM (CBRAM by using the Metropolis Monte Carlo algorithm and suggests a possible explanation for this phenomenon. The simulation method is demonstrated over a Cu/HfO2 structure, starting from a random initial distribution of oxygen vacancies (OV defects in the resistive switching layer, to a formed CF and ending in a ruptured state. the results indicate that “Hot Spots” (HS, where agglomeration of OV trap like states for electron hopping based conduction induce local heating, create favorable energy conditions to attract diffused metal species originating from the top electrode. While HS may be created and annihilated by random OV generation and recombination processes, the precipitated metal forms a stem out of which a CF could evolve. The CF stem’s final growth stage is mainly driven by drift and diffusion. This process may lead to the formation of one or more CFs as a function of the forming bias voltage. This bias dependence is demonstrated over a large range, where the creation of a single, double and multiple CFs are shown. In addition, the reset process of the multi CF device is presented, and the experimentally observed, step like, gradual CBRAM reset is verified. The simulated results are in good agreement with experimental data and promote the idea that OV defect engineering may be used to improve CBRAM performance.
Balu, Prabu
cracking issue, and 3) the effect of composition and composition gradient of Ni and WC on the slurry erosion resistance over a wide range of erosion conditions. This thesis presents a set of numerical and experimental methods in order to address the challenges mentioned above. A three-dimensional (3-D) computational fluid dynamics (CFD) based powder flow model and three vision based techniques were developed in order to visualize the process of feeding the Ni-WC powder in the LBPD process. The results provide the guidelines for efficiently feeding the Ni-WC composite powder into the laser-formed molten pool. The finite element (FE) based experimentally verified 3-D thermal and thermo-mechanical models are developed in order to understand the thermal and stress evolutions in Ni-WC composite material during the LBPD process. The models address the effect of the process variables, preheating temperature, and different mass fractions of WC in Ni on thermal cycles and stress distributions within the deposited material. The slurry erosion behavior of the single and multilayered deposits of Ni-WC composite material produced by the LBPD process is investigated using an accelerated slurry erosion testing machine and a 3-D FE dynamic model. The verified model is used to identify the appropriate composition and composition gradient of Ni-WC composite material required to achieve erosion resistance over a wide range of erosion conditions.
Dedinec, Aleksandar; Gajduk, Andrej; Markovska, Natasa; Kocarev, Ljupco
2016-01-01
We consider an integration of renewable energy into transport and electricity sectors through vehicle to grid (V2G) technologies for an energy system that is predominantly based on lignite. The national energy system of Macedonia is modeled using EnergyPLAN which integrates energy for electricity, transport and heat, and includes hourly fluctuations in human needs and the environment. We show that electric-vehicles can provide the necessary storage enabling a fully renewable energy profile for Macedonia that can match the country's growing demand for energy. Furthermore, a large penetration of electric vehicles leads to a dramatic reduction of 47% of small particles and other air pollutants generated by car traffic in 2050.
Dedinec, A.; Jovanovski, B.; Gajduk, A.; Markovska, N.; Kocarev, L.
2016-05-01
We consider an integration of renewable energy into transport and electricity sectors through vehicle to grid (V2G) technologies for an energy system that is predominantly based on lignite. The national energy system of Macedonia is modeled using EnergyPLAN which integrates energy for electricity, transport and heat, and includes hourly fluctuations in human needs and the environment. We show that electric-vehicles can provide the necessary storage enabling a fully renewable energy profile for Macedonia that can match the country's growing demand for energy. Furthermore, a large penetration of electric vehicles leads to a dramatic reduction of 47% of small particles and other air pollutants generated by car traffic in 2050.
Design and optimization of zero-energy-consumption based solar energy residential building systems
Zheng, D. L.; Yu, L. J.; Tan, H. W.
2017-11-01
Energy consumption of residential buildings has grown fast in recent years, thus raising a challenge on zero energy residential building (ZERB) systems, which aim at substantially reducing energy consumption of residential buildings. Thus, how to facilitate ZERB has become a hot but difficult topic. In the paper, we put forward the overall design principle of ZERB based on analysis of the systems’ energy demand. In particular, the architecture for both schematic design and passive technology is optimized and both energy simulation analysis and energy balancing analysis are implemented, followed by committing the selection of high-efficiency appliance and renewable energy sources for ZERB residential building. In addition, Chinese classical residential building has been investigated in the proposed case, in which several critical aspects such as building optimization, passive design, PV panel and HVAC system integrated with solar water heater, Phase change materials, natural ventilation, etc., have been taken into consideration.
Jang, In Gwun; Kim, Il Yong; Kwak, Byung Ban
2009-01-01
In bone-remodeling studies, it is believed that the morphology of bone is affected by its internal mechanical loads. From the 1970s, high computing power enabled quantitative studies in the simulation of bone remodeling or bone adaptation. Among them, Huiskes et al. (1987, "Adaptive Bone Remodeling Theory Applied to Prosthetic Design Analysis," J. Biomech. Eng., 20, pp. 1135-1150) proposed a strain energy density based approach to bone remodeling and used the apparent density for the characterization of internal bone morphology. The fundamental idea was that bone density would increase when strain (or strain energy density) is higher than a certain value and bone resorption would occur when the strain (or strain energy density) quantities are lower than the threshold. Several advanced algorithms were developed based on these studies in an attempt to more accurately simulate physiological bone-remodeling processes. As another approach, topology optimization originally devised in structural optimization has been also used in the computational simulation of the bone-remodeling process. The topology optimization method systematically and iteratively distributes material in a design domain, determining an optimal structure that minimizes an objective function. In this paper, we compared two seemingly different approaches in different fields-the strain energy density based bone-remodeling algorithm (biomechanical approach) and the compliance based structural topology optimization method (mechanical approach)-in terms of mathematical formulations, numerical difficulties, and behavior of their numerical solutions. Two numerical case studies were conducted to demonstrate their similarity and difference, and then the solution convergences were discussed quantitatively.
Directory of Open Access Journals (Sweden)
Nee A. E.
2015-01-01
Full Text Available Plane problem of thermogravitational convection in a closed rectangular cavity is numerically solved in conditions of radiant energy supply to the one of the boundaries. Differential heat transfer parameters (fields of temperatures and stream functions for the conjugate (only vertical walls, only horizontal, vertical and horizontal walls and the nonconjugate formulation are obtained. Temperature distributions in the Y direction in the cross section along the axis of symmetry showed that the presence of heat-conducting finite thickness walls leads to a redistribution of the energy which is accumulated by gas and enclosure structures.
Ionic liquid-based green processes for energy production.
Zhang, Suojiang; Sun, Jian; Zhang, Xiaochun; Xin, Jiayu; Miao, Qingqing; Wang, Jianji
2014-11-21
To mitigate the growing pressure on resource depletion and environment degradation, the development of green processes for the production of renewable energy is highly required. As a class of novel and promising media, ionic liquids (ILs) have shown infusive potential applications in energy production. Aiming to offer a critical overview regarding the new challenges and opportunities of ILs for developing green processes of renewable energy, this article emphasises the role of ILs as catalysts, solvents, or electrolytes in three broadly interesting energy production processes from renewable resources, such as CO2 conversion to fuels and fuel additives, biomass pretreatment and conversion to biofuels, as well as solar energy and energy storage. It is expected that this article will stimulate a generation of new ideas and new technologies in IL-based renewable energy production.
Paper‐Based Electrodes for Flexible Energy Storage Devices
Yao, Bin; Zhang, Jing; Kou, Tianyi; Song, Yu; Liu, Tianyu
2017-01-01
Paper‐based materials are emerging as a new category of advanced electrodes for flexible energy storage devices, including supercapacitors, Li‐ion batteries, Li‐S batteries, Li‐oxygen batteries. This review summarizes recent advances in the synthesis of paper‐based electrodes, including paper‐supported electrodes and paper‐like electrodes. Their structural features, electrochemical performances and implementation as electrodes for flexible energy storage devices including supercapacitors and batteries are highlighted and compared. Finally, we also discuss the challenges and opportunity of paper‐based electrodes and energy storage devices. PMID:28725532
An Automated Energy Detection Algorithm Based on Consecutive Mean Excision
2018-01-01
ARL-TR-8268 ● JAN 2018 US Army Research Laboratory An Automated Energy Detection Algorithm Based on Consecutive Mean Excision...not return it to the originator. ARL-TR-8268 ● JAN 2018 US Army Research Laboratory An Automated Energy Detection Algorithm...2018 2. REPORT TYPE Technical Report 3. DATES COVERED (From - To) 1 October 2016–30 September 2017 4. TITLE AND SUBTITLE An Automated Energy
Scenario simulation based assessment of subsurface energy storage
Beyer, C.; Bauer, S.; Dahmke, A.
2014-12-01
Energy production from renewable sources such as solar or wind power is characterized by temporally varying power supply. The politically intended transition towards renewable energies in Germany („Energiewende") hence requires the installation of energy storage technologies to compensate for the fluctuating production. In this context, subsurface energy storage represents a viable option due to large potential storage capacities and the wide prevalence of suited geological formations. Technologies for subsurface energy storage comprise cavern or deep porous media storage of synthetic hydrogen or methane from electrolysis and methanization, or compressed air, as well as heat storage in shallow or moderately deep porous formations. Pressure build-up, fluid displacement or temperature changes induced by such operations may affect local and regional groundwater flow, geomechanical behavior, groundwater geochemistry and microbiology. Moreover, subsurface energy storage may interact and possibly be in conflict with other "uses" like drinking water abstraction or ecological goods and functions. An utilization of the subsurface for energy storage therefore requires an adequate system and process understanding for the evaluation and assessment of possible impacts of specific storage operations on other types of subsurface use, the affected environment and protected entities. This contribution presents the framework of the ANGUS+ project, in which tools and methods are developed for these types of assessments. Synthetic but still realistic scenarios of geological energy storage are derived and parameterized for representative North German storage sites by data acquisition and evaluation, and experimental work. Coupled numerical hydraulic, thermal, mechanical and reactive transport (THMC) simulation tools are developed and applied to simulate the energy storage and subsurface usage scenarios, which are analyzed for an assessment and generalization of the imposed THMC
Westphalen, H.; Spjeldvik, W. N.
1982-01-01
A theoretical method by which the energy dependence of the radial diffusion coefficient may be deduced from spectral observations of the particle population at the inner edge of the earth's radiation belts is presented. This region has previously been analyzed with numerical techniques; in this report an analytical treatment that illustrates characteristic limiting cases in the L shell range where the time scale of Coulomb losses is substantially shorter than that of radial diffusion (L approximately 1-2) is given. It is demonstrated both analytically and numerically that the particle spectra there are shaped by the energy dependence of the radial diffusion coefficient regardless of the spectral shapes of the particle populations diffusing inward from the outer radiation zone, so that from observed spectra the energy dependence of the diffusion coefficient can be determined. To insure realistic simulations, inner zone data obtained from experiments on the DIAL, AZUR, and ESRO 2 spacecraft have been used as boundary conditions. Excellent agreement between analytic and numerical results is reported.
Hydrogen-based electrochemical energy storage
Simpson, Lin Jay
2013-08-06
An energy storage device (100) providing high storage densities via hydrogen storage. The device (100) includes a counter electrode (110), a storage electrode (130), and an ion conducting membrane (120) positioned between the counter electrode (110) and the storage electrode (130). The counter electrode (110) is formed of one or more materials with an affinity for hydrogen and includes an exchange matrix for elements/materials selected from the non-noble materials that have an affinity for hydrogen. The storage electrode (130) is loaded with hydrogen such as atomic or mono-hydrogen that is adsorbed by a hydrogen storage material such that the hydrogen (132, 134) may be stored with low chemical bonding. The hydrogen storage material is typically formed of a lightweight material such as carbon or boron with a network of passage-ways or intercalants for storing and conducting mono-hydrogen, protons, or the like. The hydrogen storage material may store at least ten percent by weight hydrogen (132, 134) at ambient temperature and pressure.
Zhou, Wenhe; He, Xuan; Wu, Jianyun; Wang, Liangbi; Wang, Liangcheng
2017-07-01
The parallel plate capacitive humidity sensor based on the grid upper electrode is considered to be a promising one in some fields which require a humidity sensor with better dynamic characteristics. To strengthen the structure and balance the electric charge of the grid upper electrode, a strip is needed. However, it is the strip that keeps the dynamic characteristics of the sensor from being further improved. The numerical method is time- and cost-saving, but the numerical study on the response time of the sensor is just of bits and pieces. The numerical models presented by these studies did not consider the porosity effect of the polymer film on the dynamic characteristics. To overcome the defect of the grid upper electrode, a new structure of the upper electrode is provided by this paper first, and then a model considering the porosity effects of the polymer film on the dynamic characteristics is presented and validated. Finally, with the help of software FLUENT, parameter effects on the response time of the humidity sensor based on the microhole upper electrode are studied by the numerical method. The numerical results show that the response time of the microhole upper electrode sensor is 86% better than that of the grid upper electrode sensor, the response time of humidity sensor can be improved by reducing the hole spacing, increasing the aperture, reducing film thickness, and reasonably enlarging the porosity of the film.
Schroeder, Matthias; Jankowski, Cedric; Hammitzsch, Martin; Wächter, Joachim
2014-05-01
Thousands of numerical tsunami simulations allow the computation of inundation and run-up along the coast for vulnerable areas over the time. A so-called Matching Scenario Database (MSDB) [1] contains this large number of simulations in text file format. In order to visualize these wave propagations the scenarios have to be reprocessed automatically. In the TRIDEC project funded by the seventh Framework Programme of the European Union a Virtual Scenario Database (VSDB) and a Matching Scenario Database (MSDB) were established amongst others by the working group of the University of Bologna (UniBo) [1]. One part of TRIDEC was the developing of a new generation of a Decision Support System (DSS) for tsunami Early Warning Systems (TEWS) [2]. A working group of the GFZ German Research Centre for Geosciences was responsible for developing the Command and Control User Interface (CCUI) as central software application which support operator activities, incident management and message disseminations. For the integration and visualization in the CCUI, the numerical tsunami simulations from MSDB must be converted into the shapefiles format. The usage of shapefiles enables a much easier integration into standard Geographic Information Systems (GIS). Since also the CCUI is based on two widely used open source products (GeoTools library and uDig), whereby the integration of shapefiles is provided by these libraries a priori. In this case, for an example area around the Western Iberian margin several thousand tsunami variations were processed. Due to the mass of data only a program-controlled process was conceivable. In order to optimize the computing efforts and operating time the use of an existing GFZ High Performance Computing Cluster (HPC) had been chosen. Thus, a geospatial software was sought after that is capable for parallel processing. The FOSS tool Geospatial Data Abstraction Library (GDAL/OGR) was used to match the coordinates with the wave heights and generates the
Modeling of a piezoelectric/piezomagnetic nano energy harvester based on two dimensional theory
Yan, Zhi
2018-01-01
This work presents a two dimensional theory for a piezoelectric/piezomagnetic bilayer nanoplate in coupled extensional and flexural vibrations with both flexoelectric and surface effects. The magneto-electro-elastic (MEE) coupling equations are derived from three-dimensional equations and Kirchhoff plate theory. Based on the developed theory, a piezoelectric/piezomagnetic nano energy harvester is proposed, which can generate electricity under time-harmonic applied magnetic field. The approximate solutions for the mechanical responses and voltage of the energy harvester are obtained using the weighted residual method. Results show that the properties of the proposed energy harvester are size-dependent due to the flexoelectric and surface effects, and such effects are more pronounced when the bilayer thickness is reduced to dozens of nanometers. It is also found that the magnetoelectric coupling coefficient and power density of the energy harvester are sensitive to the load resistance, the thickness fraction of the piezoelectric or the piezomagnetic layer and damping ratios. Moreover, results indicate that the flexoelectric effect could be made use to build a dielectric/piezomagnetic nano energy harvester. This work provides modeling techniques and numerical methods for investigating the size-dependent properties of MEE nanoplate-based energy harvester and could be helpful for designing nano energy harvesters using the principle of flexoelectricity.
Energy transfer in erbium doped optical waveguides based on silicon
Kik, Pieter Geert
2000-01-01
Energy transfer in erbium doped optical waveguides based on silicon This thesis describes the energy transfer processes occurring in materials that can be used for the fabrication of silicon compatible optical integrated circuits, operating at 1.54 mm.The thesis consists of three parts: Part I
Comparison of gas dehydration methods based on energy ...
African Journals Online (AJOL)
Comparison of gas dehydration methods based on energy consumption. ... This study compares three conventional methods of natural gas (Associated Natural Gas) dehydration to carry out the dehydration process and suitability of use on the basis of energy requirement. These methods are Triethylene Glycol (TEG) ...
Energy enhancer for mask based laser materials processing
DEFF Research Database (Denmark)
Bastue, Jens; Olsen, Flemmming Ove
1996-01-01
A device capable of drastically improving the energy efficiency of present mask based laser materials processing systems is presented. Good accordance between experiments and simulations for a TEA-CO2 laser system designed for laser marking has been demonstrated. The energy efficiency may...
Energy Conservation in the Home. Performance Based Lesson Plans.
Alabama State Dept. of Education, Montgomery. Home Economics Service.
These ten performance-based lesson plans concentrate on tasks related to energy conservation in the home. They are (1) caulk cracks, holes, and joints; (2) apply weatherstripping to doors and windows; (3) add plastic/solar screen window covering; (4) arrange furniture for saving energy; (5) set heating/cooling thermostat; (6) replace faucet…
He, Shaobo; Sun, Kehui; Mei, Xiaoyong; Yan, Bo; Xu, Siwei
2017-01-01
In this paper, the numerical solutions of conformable fractional-order linear and nonlinear equations are obtained by employing the constructed conformable Adomian decomposition method (CADM). We found that CADM is an effective method for numerical solution of conformable fractional-order differential equations. Taking the conformable fractional-order simplified Lorenz system as an example, the numerical solution and chaotic behaviors of the conformable fractional-order simplified Lorenz system are investigated. It is found that rich dynamics exist in the conformable fractional-order simplified Lorenz system, and the minimum order for chaos is even less than 2. The results are validated by means of bifurcation diagram, Lyapunov characteristic exponents and phase portraits.
Cepeda, Francisco Javier Delgado
2017-01-01
This work presents a proposed model in blended learning for a numerical methods course evolved from traditional teaching into a research lab in scientific visualization. The blended learning approach sets a differentiated and flexible scheme based on a mobile setup and face to face sessions centered on a net of research challenges. Model is…
Maher, G.D.; Hulshoff, S.J.
2014-01-01
The Variational Germano Identity [1, 2] is used to optimize the coefficients of residual-based subgrid-scale models that arise from the application of a Variational Multiscale Method [3, 4]. It is demonstrated that numerical iterative methods can be used to solve the Germano relations to obtain
Energy Optimal Control Strategy of PHEV Based on PMP Algorithm
Directory of Open Access Journals (Sweden)
Tiezhou Wu
2017-01-01
Full Text Available Under the global voice of “energy saving” and the current boom in the development of energy storage technology at home and abroad, energy optimal control of the whole hybrid electric vehicle power system, as one of the core technologies of electric vehicles, is bound to become a hot target of “clean energy” vehicle development and research. This paper considers the constraints to the performance of energy storage system in Parallel Hybrid Electric Vehicle (PHEV, from which lithium-ion battery frequently charges/discharges, PHEV largely consumes energy of fuel, and their are difficulty in energy recovery and other issues in a single cycle; the research uses lithium-ion battery combined with super-capacitor (SC, which is hybrid energy storage system (Li-SC HESS, working together with internal combustion engine (ICE to drive PHEV. Combined with PSO-PI controller and Li-SC HESS internal power limited management approach, the research proposes the PHEV energy optimal control strategy. It is based on revised Pontryagin’s minimum principle (PMP algorithm, which establishes the PHEV vehicle simulation model through ADVISOR software and verifies the effectiveness and feasibility. Finally, the results show that the energy optimization control strategy can improve the instantaneity of tracking PHEV minimum fuel consumption track, implement energy saving, and prolong the life of lithium-ion batteries and thereby can improve hybrid energy storage system performance.
ENERGY OPTIMIZATION IN CLUSTER BASED WIRELESS SENSOR NETWORKS
Directory of Open Access Journals (Sweden)
T. SHANKAR
2014-04-01
Full Text Available Wireless sensor networks (WSN are made up of sensor nodes which are usually battery-operated devices, and hence energy saving of sensor nodes is a major design issue. To prolong the networks lifetime, minimization of energy consumption should be implemented at all layers of the network protocol stack starting from the physical to the application layer including cross-layer optimization. Optimizing energy consumption is the main concern for designing and planning the operation of the WSN. Clustering technique is one of the methods utilized to extend lifetime of the network by applying data aggregation and balancing energy consumption among sensor nodes of the network. This paper proposed new version of Low Energy Adaptive Clustering Hierarchy (LEACH, protocols called Advanced Optimized Low Energy Adaptive Clustering Hierarchy (AOLEACH, Optimal Deterministic Low Energy Adaptive Clustering Hierarchy (ODLEACH, and Varying Probability Distance Low Energy Adaptive Clustering Hierarchy (VPDL combination with Shuffled Frog Leap Algorithm (SFLA that enables selecting best optimal adaptive cluster heads using improved threshold energy distribution compared to LEACH protocol and rotating cluster head position for uniform energy dissipation based on energy levels. The proposed algorithm optimizing the life time of the network by increasing the first node death (FND time and number of alive nodes, thereby increasing the life time of the network.
Yan, Zhen-Gang; Sun, Weiping; Ren, Meng; Lv, Hongpeng; Li, Jie; Xue, Liang; Yan, Keding; Wang, Shouyu
2018-01-01
In order to quantitatively analyze scattering from two dimensional randomly rough Gaussian surfaces, Kirchhoff approximation method is adopted in numerical calculation for analyzing full angular Stokes vectors of light scattering. With studying both the p- and s-polarized scattering fields from various materials such as metals and dielectrics, it is found that V components of scattering light from metals and dielectrics are different. Via analytical calculation according to slope probability density, the V component difference is attributed to refractive index of materials. Both numerical and analytical calculations prove the V component difference in light scattering can act as a criterion for metal and dielectric identification.
Numerical Study of Wind Turbine Wake Modeling Based on a Actuator Surface Model
DEFF Research Database (Denmark)
Zhou, Huai-yang; Xu, Chang; Han, Xing Xing
2017-01-01
In the Actuator Surface Model (ALM), the turbine blades are represented by porous surfaces of velocity and pressure discontinuities to model the action of lifting surfaces on the flow. The numerical simulation is implemented on FLUENT platform combined with N-S equations. This model is improved...... and far wake of a Nibe A wind turbine, which combines wake velocity, turbulent intensity and vortex structure. Results show that ASM has better prediction accuracy and verify it's feasibility on numerical simulation of wind turbine wake....
2017-01-01
Although Arabic numerals (like ‘2016’ and ‘3.14’) are ubiquitous, we show that in interactive computer applications they are often misleading and surprisingly unreliable. We introduce interactive numerals as a new concept and show, like Roman numerals and Arabic numerals, interactive numerals introduce another way of using and thinking about numbers. Properly understanding interactive numerals is essential for all computer applications that involve numerical data entered by users, including finance, medicine, aviation and science. PMID:28484609
Probabilistic regional wind power forecasts based on calibrated Numerical Weather Forecast ensembles
Späth, Stephan; von Bremen, Lueder; Junk, Constantin; Heinemann, Detlev
2014-05-01
With increasing shares of installed wind power in Germany, accurate forecasts of wind speed and power get increasingly important for the grid integration of Renewable Energies. Applications like grid management and trading also benefit from uncertainty information. This uncertainty information can be provided by ensemble forecasts. These forecasts often exhibit systematic errors such as biases and spread deficiencies. The errors can be reduced by statistical post-processing. We use forecast data from the regional Numerical Weather Prediction model COSMO-DE EPS as input to regional wind power forecasts. In order to enhance the power forecast, we first calibrate the wind speed forecasts against the model analysis, so some of the model's systematic errors can be removed. Wind measurements at every grid point are usually not available and as we want to conduct grid zone forecasts, the model analysis is the best target for calibration. We use forecasts from the COSMO-DE EPS, a high-resolution ensemble prediction system with 20 forecast members. The model covers the region of Germany and surroundings with a vertical resolution of 50 model levels and a horizontal resolution of 0.025 degrees (approximately 2.8 km). The forecast range is 21 hours with model output available on an hourly basis. Thus, we use it for shortest-term wind power forecasts. The COSMO-DE EPS was originally designed with a focus on forecasts of convective precipitation. The COSMO-DE EPS wind speed forecasts at hub height were post-processed by nonhomogenous Gaussian regression (NGR; Thorarinsdottir and Gneiting, 2010), a calibration method that fits a truncated normal distribution to the ensemble wind speed forecasts. As calibration target, the model analysis was used. The calibration is able to remove some deficits of the COSMO-DE EPS. In contrast to the raw ensemble members, the calibrated ensemble members do not show anymore the strong correlations with each other and the spread-skill relationship
Energy-Based Devices in Treatment of Acne Vulgaris.
Handler, Marc Z; Bloom, Bradley S; Goldberg, David J
2016-05-01
Acne vulgaris is a chronic dermatologic complaint with a multifactorial cause. Traditionally, antibiotics and retinoids have been used to manage the condition; patient compliance has been an ongoing issue. A variety of energy-based devices have been reported to be effective in the treatment of acne vulgaris. To review and summarize the current literature specific to treatment of acne vulgaris with energy-based devices. A review of the current literature of energy-based devices used for the treatment of acne vulgaris. Although limited randomized controlled trials for the treatment of acne have been performed, significant clinical improvement of acne vulgaris, especially of inflammatory lesions, has been demonstrated with a variety of energy-based devices. Newer approaches may lead to even better results.
Derevtsov, E. Yu; Louis, A. K.; Maltseva, S. V.; Polyakova, A. P.; Svetov, I. E.
2017-12-01
A problem of reconstruction of 2D vector or symmetric 2-tensor fields by their known ray transforms is considered. Two numerical approaches based on the method of approximate inverse are suggested for solving the problem. The first method allows to recover components of a vector or tensor field, and the second reconstructs its potentials in the sense of feature reconstruction, where the observation operator assigns to a field its potential. Numerical simulations show good results of reconstruction of the sought-for fields or their solenoidal or potential parts from its ray transforms.
Numerical simulations based on probe measurements in EUV-induced hydrogen plasma
Abrikosov, Alex; Reshetnyak, Viktor; Astakhov, Dmitry; Dolgov, Alexandr; Yakushev, Oleg; Lopaev, Dmitry; Krivtsun, Vladimir
2017-04-01
We use the two-dimensional particle-in-cell model with Monte Carlo collisions to study the plasma induced in hydrogen by short pulses of extreme ultraviolet (EUV) radiation at wavelengths in the range 10-20 nm with a pulse duration of about 40 ns (FWHM). This plasma is formed via both photoionization by the high-energy EUV photons and by the secondary photoelectrons emitted from the hydrogen molecules and the irradiated surface. The latter process can be enhanced by the external electric field that accelerates the electrons. In order to establish a base for our model so as to obtain accurate results, we record a temporally-resolved series of current-voltage characteristics for a small probing electrode inserted into EUV-induced hydrogen plasma. We then resort to simulating this plasma in the same geometry with the probe in our model which we validate by matching its results to the experimentally measured dynamics of the probe current-voltage curves. Having validated the model this way, we use this model as an independent instrument capable of obtaining the spatiotemporal picture of EUV-induced plasma evolution. We use this instrument to study the plasma formation during the EUV pulse and point out the processes that take part in forming this plasma, such as impact ionization and direct ionization by EUV photons.
Assessment of Energy Efficient and Model Based Control
2017-06-15
US Army Research Laboratory Autonomous Systems Division Vehicle Technology Directorate (ATTN: RDRL-VTA) Aberdeen Proving Ground , MD 21005-5069...ARL-TR-8042 ● JUNE 2017 US Army Research Laboratory Assessment of Energy-Efficient and Model- Based Control by Craig Lennon...originator. ARL-TR-8042 ● JUNE 2017 US Army Research Laboratory Assessment of Energy-Efficient and Model- Based Control by Craig
Cloud-Based Numerical Weather Prediction for Near Real-Time Forecasting and Disaster Response
Molthan, Andrew; Case, Jonathan; Venners, Jason; Schroeder, Richard; Checchi, Milton; Zavodsky, Bradley; Limaye, Ashutosh; O'Brien, Raymond
2015-01-01
The use of cloud computing resources continues to grow within the public and private sector components of the weather enterprise as users become more familiar with cloud-computing concepts, and competition among service providers continues to reduce costs and other barriers to entry. Cloud resources can also provide capabilities similar to high-performance computing environments, supporting multi-node systems required for near real-time, regional weather predictions. Referred to as "Infrastructure as a Service", or IaaS, the use of cloud-based computing hardware in an on-demand payment system allows for rapid deployment of a modeling system in environments lacking access to a large, supercomputing infrastructure. Use of IaaS capabilities to support regional weather prediction may be of particular interest to developing countries that have not yet established large supercomputing resources, but would otherwise benefit from a regional weather forecasting capability. Recently, collaborators from NASA Marshall Space Flight Center and Ames Research Center have developed a scripted, on-demand capability for launching the NOAA/NWS Science and Training Resource Center (STRC) Environmental Modeling System (EMS), which includes pre-compiled binaries of the latest version of the Weather Research and Forecasting (WRF) model. The WRF-EMS provides scripting for downloading appropriate initial and boundary conditions from global models, along with higher-resolution vegetation, land surface, and sea surface temperature data sets provided by the NASA Short-term Prediction Research and Transition (SPoRT) Center. This presentation will provide an overview of the modeling system capabilities and benchmarks performed on the Amazon Elastic Compute Cloud (EC2) environment. In addition, the presentation will discuss future opportunities to deploy the system in support of weather prediction in developing countries supported by NASA's SERVIR Project, which provides capacity building
Directory of Open Access Journals (Sweden)
Daungruthai Jarukanont
Full Text Available Chromaffin cells release catecholamines by exocytosis, a process that includes vesicle docking, priming and fusion. Although all these steps have been intensively studied, some aspects of their mechanisms, particularly those regarding vesicle transport to the active sites situated at the membrane, are still unclear. In this work, we show that it is possible to extract information on vesicle motion in Chromaffin cells from the combination of Langevin simulations and amperometric measurements. We developed a numerical model based on Langevin simulations of vesicle motion towards the cell membrane and on the statistical analysis of vesicle arrival times. We also performed amperometric experiments in bovine-adrenal Chromaffin cells under Ba2+ stimulation to capture neurotransmitter releases during sustained exocytosis. In the sustained phase, each amperometric peak can be related to a single release from a new vesicle arriving at the active site. The amperometric signal can then be mapped into a spike-series of release events. We normalized the spike-series resulting from the current peaks using a time-rescaling transformation, thus making signals coming from different cells comparable. We discuss why the obtained spike-series may contain information about the motion of all vesicles leading to release of catecholamines. We show that the release statistics in our experiments considerably deviate from Poisson processes. Moreover, the interspike-time probability is reasonably well described by two-parameter gamma distributions. In order to interpret this result we computed the vesicles' arrival statistics from our Langevin simulations. As expected, assuming purely diffusive vesicle motion we obtain Poisson statistics. However, if we assume that all vesicles are guided toward the membrane by an attractive harmonic potential, simulations also lead to gamma distributions of the interspike-time probability, in remarkably good agreement with experiment. We
Energy conservation technologies based on thermodynamic principles
Energy Technology Data Exchange (ETDEWEB)
Hirata, Masaru [Shibaura Institute of Technology of Technology, Tokyo (Japan)
1996-12-31
In order to reduce CO{sub 2} emission to prevent global warming, the most promising way for electric generation in the Northeast Asia is to introduce cogeneration and {open_quotes}repowering{close_quotes} technologies based on high temperature gas turbines fueled by natural gas. Especially the old type coal burning boiler-steam turbine plants should be retrofit by introducing gas turbines to become highly efficient combined cycle. Same technologies should be applied to the old garbage incineration plants and/or even to the nuclear power plants. The exhaust heat or steam should become much increased and it should be utilized as the process heat for industries or heat supply as the distinct heating or cooling for residential area. This paper introduces a brief survey of these new technologies.
Verstappen, R.
1991-01-01
This paper deals with an efficient numerical method for the fully lubricated line contact between a rotating, deformable cylinder and a rigid surface. By exploiting the dynamic variation structure of this non-linear problem the deformation of and the pressure at the free, contact boundary are
Numerical model of a non-steady atmospheric planetary boundary layer, based on similarity theory
DEFF Research Database (Denmark)
Zilitinkevich, S.S.; Fedorovich, E.E.; Shabalova, M.V.
1992-01-01
A numerical model of a non-stationary atmospheric planetary boundary layer (PBL) over a horizontally homogeneous flat surface is derived on the basis of similarity theory. The two most typical turbulence regimes are reproduced: one corresponding to a convectively growing PBL and another correspon...
A 4-Mid-Node Plane Model of Base Force Element Method on Complementary Energy Principle
Directory of Open Access Journals (Sweden)
Yinghua Liu
2013-01-01
Full Text Available Using the base forces as fundamental variables to describe the stress state and the displacement gradients that are the conjugate variables of the base forces to describe the deformation state for the two-dimensional elasticity problems, a 4-mid-node plane model of base force element method (BFEM based on complementary energy principle is proposed. In this paper, the complementary energy of an element of the BFEM is constructed by using the base forces. The equilibrium conditions are released by the Lagrange multiplier method, and a modified complementary energy principle described by the base forces is obtained. The formulation of the 4-mid-node plane element of the BFEM is derived by assuming that the stress is uniformly distributed on each edge of the plane elements. A procedure of the BFEM on complementary energy principle is developed using MATLAB language. The numerical results of examples show that this model of the BFEM has high precision and is free from mesh sensitivity. This model shows good performances.
The Energy Disclosure Among Energy Intensive Companies in Malaysia: A Resource Based Approach
Directory of Open Access Journals (Sweden)
Elyana Tasrip Nabila
2017-01-01
Full Text Available This study examines the extent of, and factors influencing, energy disclosure in Malaysia. We content analysed the annual reports of top 100 energy intensive companies for the year 2014. Using resource-based theory, we analysed if companies’ tangible and intangible resources as well as human capabilities determine the extent of energy disclosure. Overall, the disclosure is low with an average ‘occurrence’ of energy-related information of 3.53. We also find that the ‘Top Brand Value’ companies and companies with a larger number of directors serving on the board tend to provide greater energy disclosures. However, other variables - in particular tangible resources - have no significant influence. The findings provide tentative evidence to support the arguments of resource-based theory.
An Energy Efficiency Evaluation Method Based on Energy Baseline for Chemical Industry
Directory of Open Access Journals (Sweden)
Dong-mei Yao
2016-01-01
Full Text Available According to the requirements and structure of ISO 50001 energy management system, this study proposes an energy efficiency evaluation method based on energy baseline for chemical industry. Using this method, the energy plan implementation effect in the processes of chemical production can be evaluated quantitatively, and evidences for system fault diagnosis can be provided. This method establishes the energy baseline models which can meet the demand of the different kinds of production processes and gives the general solving method of each kind of model according to the production data. Then the energy plan implementation effect can be evaluated and also whether the system is running normally can be determined through the baseline model. Finally, this method is used on cracked gas compressor unit of ethylene plant in some petrochemical enterprise; it can be proven that this method is correct and practical.
Energy Storage System Based on Cascaded Multilevel Inverter with Decoupled Energy Balancing Control
Directory of Open Access Journals (Sweden)
Cao Yuanzhi
2015-01-01
Full Text Available This paper presents a three phase cascaded multilevel inverter based supercapacitor (SC energy storage system with novel structure and control strategy to maintain the energy balance of between phases. Every two phases are coupled with a series LC filter. With the filter, SC cells in different phases could exchange energy with an auxiliary power flow at high frequency. The auxiliary power flow is orthogonal to the primary power flow. The phase difference between high frequency voltage and current components of each phase determines whether the energy is absorbed into or released from its SC cells. Unlike traditional energy balancing strategies, the proposed method is independent to the fundamental real power drawn by the energy storage system. Simulation results confirmed the effects of proposed theories.
Blumenröther, E; Wollweber, M; Roth, B
2016-01-01
In this article we characterize optoacoustic signals generated from layered tissue phantoms via short laser pulses by experimental and numerical means. In particular, we consider the case where scattering is effectively negligible and the absorbed energy density follows Beer-Lambert's law, i.e. is characterized by an exponential decay within the layers and discontinuities at interfaces. We complement experiments on samples with multiple layers, where the material properties are known a priori, with numerical calculations for a pointlike detector, tailored to suit our experimental setup. Experimentally, we characterize the acoustic signal observed by a piezoelectric detector in the acoustic far-field in backward mode and we discuss the implication of acoustic diffraction on our measurements. We further attempt an inversion of an OA signal in the far-field approximation.
Monitoring and optimization of energy consumption of base transceiver stations
Spagnuolo, Antonio; Vetromile, Carmela; Formosi, Roberto; Lubritto, Carmine
2015-01-01
The growth and development of the mobile phone network has led to an increased demand for energy by the telecommunications sector, with a noticeable impact on the environment. Monitoring of energy consumption is a great tool for understanding how to better manage this consumption and find the best strategy to adopt in order to maximize reduction of unnecessary usage of electricity. This paper reports on a monitoring campaign performed on six Base Transceiver Stations (BSs) located central Italy, with different technology, typology and technical characteristics. The study focuses on monitoring energy consumption and environmental parameters (temperature, noise, and global radiation), linking energy consumption with the load of telephone traffic and with the air conditioning functions used to cool the transmission equipment. Moreover, using experimental data collected, it is shown, with a Monte Carlo simulation based on power saving features, how the BS monitored could save energy.
Material identification based upon energy-dependent attenuation of neutrons
Marleau, Peter
2015-10-06
Various technologies pertaining to identifying a material in a sample and imaging the sample are described herein. The material is identified by computing energy-dependent attenuation of neutrons that is caused by presence of the sample in travel paths of the neutrons. A mono-energetic neutron generator emits the neutron, which is downscattered in energy by a first detector unit. The neutron exits the first detector unit and is detected by a second detector unit subsequent to passing through the sample. Energy-dependent attenuation of neutrons passing through the sample is computed based upon a computed energy of the neutron, wherein such energy can be computed based upon 1) known positions of the neutron generator, the first detector unit, and the second detector unit; or 2) computed time of flight of neutrons between the first detector unit and the second detector unit.
Rolling Locomotion Control of a Biologically Inspired Quadruped Robot Based on Energy Compensation
Directory of Open Access Journals (Sweden)
Takuma Nemoto
2015-01-01
Full Text Available We have developed a biologically inspired reconfigurable quadruped robot which can perform walking and rolling locomotion and transform between walking and rolling by reconfiguring its legs. This paper presents an approach to control rolling locomotion with the biologically inspired quadruped robot. For controlling rolling locomotion, a controller which can compensate robot’s energy loss during rolling locomotion is designed based on a dynamic model of the quadruped robot. The dynamic model describes planar rolling locomotion based on an assumption that the quadruped robot does not fall down while rolling and the influences of collision and contact with the ground, and it is applied for computing the mechanical energy and a plant in a numerical simulation. The numerical simulation of rolling locomotion on the flat ground verifies the effectiveness of the proposed controller. The simulation results show that the quadruped robot can perform periodic rolling locomotion with the proposed energy-based controller. In conclusion, it is shown that the proposed control approach is effective in achieving the periodic rolling locomotion on the flat ground.
Numerical Simulation of Wake Effects in the Lee of a Farm of Wave Dragon Wave Energy Converters
DEFF Research Database (Denmark)
Beels, C.; Troch, P.; De Visch, K.
2009-01-01
The contribution of wave energy to the renewable energy supply is rising. To extract a considerable amount of wave power,Wave Energy Converters (WECs) are arranged in several rows or in a ‘farm'. The wake behind each individual WEC in the farm affects the power absorption of its neighbouring WECs....... In this paper wake effects in the lee of a single Wave Dragon WEC and multiple Wave Dragon WECs are studied in a time-dependent mild-slope equation model. The Wave Dragon WEC is a floating offshore converter of the overtopping type. The water volume of overtopped waves is first captured in a basin above mean...
Energy Harvesting Based Body Area Networks for Smart Health.
Hao, Yixue; Peng, Limei; Lu, Huimin; Hassan, Mohammad Mehedi; Alamri, Atif
2017-07-10
Body area networks (BANs) are configured with a great number of ultra-low power consumption wearable devices, which constantly monitor physiological signals of the human body and thus realize intelligent monitoring. However, the collection and transfer of human body signals consume energy, and considering the comfort demand of wearable devices, both the size and the capacity of a wearable device's battery are limited. Thus, minimizing the energy consumption of wearable devices and optimizing the BAN energy efficiency is still a challenging problem. Therefore, in this paper, we propose an energy harvesting-based BAN for smart health and discuss an optimal resource allocation scheme to improve BAN energy efficiency. Specifically, firstly, considering energy harvesting in a BAN and the time limits of human body signal transfer, we formulate the energy efficiency optimization problem of time division for wireless energy transfer and wireless information transfer. Secondly, we convert the optimization problem into a convex optimization problem under a linear constraint and propose a closed-form solution to the problem. Finally, simulation results proved that when the size of data acquired by the wearable devices is small, the proportion of energy consumed by the circuit and signal acquisition of the wearable devices is big, and when the size of data acquired by the wearable devices is big, the energy consumed by the signal transfer of the wearable device is decisive.
Energy Harvesting Based Body Area Networks for Smart Health
Directory of Open Access Journals (Sweden)
Yixue Hao
2017-07-01
Full Text Available Body area networks (BANs are configured with a great number of ultra-low power consumption wearable devices, which constantly monitor physiological signals of the human body and thus realize intelligent monitoring. However, the collection and transfer of human body signals consume energy, and considering the comfort demand of wearable devices, both the size and the capacity of a wearable device’s battery are limited. Thus, minimizing the energy consumption of wearable devices and optimizing the BAN energy efficiency is still a challenging problem. Therefore, in this paper, we propose an energy harvesting-based BAN for smart health and discuss an optimal resource allocation scheme to improve BAN energy efficiency. Specifically, firstly, considering energy harvesting in a BAN and the time limits of human body signal transfer, we formulate the energy efficiency optimization problem of time division for wireless energy transfer and wireless information transfer. Secondly, we convert the optimization problem into a convex optimization problem under a linear constraint and propose a closed-form solution to the problem. Finally, simulation results proved that when the size of data acquired by the wearable devices is small, the proportion of energy consumed by the circuit and signal acquisition of the wearable devices is big, and when the size of data acquired by the wearable devices is big, the energy consumed by the signal transfer of the wearable device is decisive.
Toward flexible polymer and paper-based energy storage devices.
Nyholm, Leif; Nyström, Gustav; Mihranyan, Albert; Strømme, Maria
2011-09-01
All-polymer and paper-based energy storage devices have significant inherent advantages in comparison with many currently employed batteries and supercapacitors regarding environmental friendliness, flexibility, cost and versatility. The research within this field is currently undergoing an exciting development as new polymers, composites and paper-based devices are being developed. In this report, we review recent progress concerning the development of flexible energy storage devices based on electronically conducting polymers and cellulose containing composites with particular emphasis on paper-based batteries and supercapacitors. We discuss recent progress in the development of the most commonly used electronically conducting polymers used in flexible device prototypes, the advantages and disadvantages of this type of energy storage devices, as well as the two main approaches used in the manufacturing of paper-based charge storage devices. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
A modified airfoil-based piezoaeroelastic energy harvester with double plunge degrees of freedom
Directory of Open Access Journals (Sweden)
Yining Wu
2016-09-01
Full Text Available In this letter, a piezoaeroelastic energy harvester based on an airfoil with double plunge degrees of freedom is proposed to additionally take advantage of the vibrational energy of the airfoil pitch motion. An analytical model of the proposed energy harvesting system is built and compared with an equivalent model using the well-explored pitch-plunge configuration. The dynamic response and average power output of the harvester are numerically studied as the flow velocity exceeds the cut-in speed (flutter speed. It is found that the harvester with double-plunge configuration generates 4%–10% more power with varying flow velocities while reducing 6% of the cut-in speed than its counterpart.
Adaptive double threshold energy detection based on Markov model for cognitive radio.
Directory of Open Access Journals (Sweden)
Yulei Liu
Full Text Available The rapid development in the area of cognitive radio technology leads the society to higher standards of spectrum sensing performance, particularly in low signal-to-noise ratio (SNR environment. This article proposes an adaptive double-threshold energy sensing method based on Markov model (ADEMM. When using the double-threshold energy sensing method, the modified Markov model that accounts for the time varying characteristic of the channel occupancy was presented to resolve the 'confused' channel state. Furthermore, in order to overcome the effect of noise uncertainty, the findings of this article introduce an adaptive double-threshold spectrum sensing method that adjusts its thresholds according to the achievable maximal detection probability. Numerical simulations show that the proposed ADEMM achieves better detection performance than the conventional double-threshold energy sensing schemes, especially in very low SNR region.
Adaptive double threshold energy detection based on Markov model for cognitive radio.
Liu, Yulei; Liang, Jun; Xiao, Nan; Yuan, Xiaogang; Zhang, Zhenhao; Hu, Meng; Hu, Yulong
2017-01-01
The rapid development in the area of cognitive radio technology leads the society to higher standards of spectrum sensing performance, particularly in low signal-to-noise ratio (SNR) environment. This article proposes an adaptive double-threshold energy sensing method based on Markov model (ADEMM). When using the double-threshold energy sensing method, the modified Markov model that accounts for the time varying characteristic of the channel occupancy was presented to resolve the 'confused' channel state. Furthermore, in order to overcome the effect of noise uncertainty, the findings of this article introduce an adaptive double-threshold spectrum sensing method that adjusts its thresholds according to the achievable maximal detection probability. Numerical simulations show that the proposed ADEMM achieves better detection performance than the conventional double-threshold energy sensing schemes, especially in very low SNR region.
Adaptive double threshold energy detection based on Markov model for cognitive radio
Xiao, Nan; Yuan, Xiaogang; Zhang, Zhenhao; Hu, Meng; Hu, Yulong
2017-01-01
The rapid development in the area of cognitive radio technology leads the society to higher standards of spectrum sensing performance, particularly in low signal-to-noise ratio (SNR) environment. This article proposes an adaptive double-threshold energy sensing method based on Markov model (ADEMM). When using the double-threshold energy sensing method, the modified Markov model that accounts for the time varying characteristic of the channel occupancy was presented to resolve the ‘confused’ channel state. Furthermore, in order to overcome the effect of noise uncertainty, the findings of this article introduce an adaptive double-threshold spectrum sensing method that adjusts its thresholds according to the achievable maximal detection probability. Numerical simulations show that the proposed ADEMM achieves better detection performance than the conventional double-threshold energy sensing schemes, especially in very low SNR region. PMID:28520782
Directory of Open Access Journals (Sweden)
Chinmaya Mahapatra
2017-12-01
Full Text Available Around the globe, innovation with integrating information and communication technologies (ICT with physical infrastructure is a top priority for governments in pursuing smart, green living to improve energy efficiency, protect the environment, improve the quality of life, and bolster economy competitiveness. Cities today faces multifarious challenges, among which energy efficiency of homes and residential dwellings is a key requirement. Achieving it successfully with the help of intelligent sensors and contextual systems would help build smart cities of the future. In a Smart home environment Home Energy Management plays a critical role in finding a suitable and reliable solution to curtail the peak demand and achieve energy conservation. In this paper, a new method named as Home Energy Management as a Service (HEMaaS is proposed which is based on neural network based Q-learning algorithm. Although several attempts have been made in the past to address similar problems, the models developed do not cater to maximize the user convenience and robustness of the system. In this paper, authors have proposed an advanced Neural Fitted Q-learning method which is self-learning and adaptive. The proposed method provides an agile, flexible and energy efficient decision making system for home energy management. A typical Canadian residential dwelling model has been used in this paper to test the proposed method. Based on analysis, it was found that the proposed method offers a fast and viable solution to reduce the demand and conserve energy during peak period. It also helps reducing the carbon footprint of residential dwellings. Once adopted, city blocks with significant residential dwellings can significantly reduce the total energy consumption by reducing or shifting their energy demand during peak period. This would definitely help local power distribution companies to optimize their resources and keep the tariff low due to curtailment of peak demand.
Mahapatra, Chinmaya; Moharana, Akshaya Kumar; Leung, Victor C M
2017-12-05
Around the globe, innovation with integrating information and communication technologies (ICT) with physical infrastructure is a top priority for governments in pursuing smart, green living to improve energy efficiency, protect the environment, improve the quality of life, and bolster economy competitiveness. Cities today faces multifarious challenges, among which energy efficiency of homes and residential dwellings is a key requirement. Achieving it successfully with the help of intelligent sensors and contextual systems would help build smart cities of the future. In a Smart home environment Home Energy Management plays a critical role in finding a suitable and reliable solution to curtail the peak demand and achieve energy conservation. In this paper, a new method named as Home Energy Management as a Service (HEMaaS) is proposed which is based on neural network based Q -learning algorithm. Although several attempts have been made in the past to address similar problems, the models developed do not cater to maximize the user convenience and robustness of the system. In this paper, authors have proposed an advanced Neural Fitted Q -learning method which is self-learning and adaptive. The proposed method provides an agile, flexible and energy efficient decision making system for home energy management. A typical Canadian residential dwelling model has been used in this paper to test the proposed method. Based on analysis, it was found that the proposed method offers a fast and viable solution to reduce the demand and conserve energy during peak period. It also helps reducing the carbon footprint of residential dwellings. Once adopted, city blocks with significant residential dwellings can significantly reduce the total energy consumption by reducing or shifting their energy demand during peak period. This would definitely help local power distribution companies to optimize their resources and keep the tariff low due to curtailment of peak demand.
Hintermüller, Michael; Rautenberg, Carlos N.; Hahn, Jooyoung
2014-05-01
Variable splitting schemes for the function space version of the image reconstruction problem with total variation regularization (TV-problem) in its primal and pre-dual formulations are considered. For the primal splitting formulation, while existence of a solution cannot be guaranteed, it is shown that quasi-minimizers of the penalized problem are asymptotically related to the solution of the original TV-problem. On the other hand, for the pre-dual formulation, a family of parametrized problems is introduced and a parameter dependent contraction of an associated fixed point iteration is established. Moreover, the theory is validated by numerical tests. Additionally, the augmented Lagrangian approach is studied, details on an implementation on a staggered grid are provided and numerical tests are shown.
Energy Technology Data Exchange (ETDEWEB)
Han, Bing; Jing, Hongyuan; Liu, Jianping; Wu, Zhangzhong [PetroChina Pipeline RandD Center, Langfang, Hebei (China); Hao, Jianbin [School of Petroleum Engineering, Southwest Petroleum University, Chengdu, Sichuan (China)
2010-07-01
Landslides have a serious impact on the integrity of oil and gas pipelines in the tough terrain of Western China. This paper introduces a solving method of axial stress, which uses numerical simulation and regression analysis for the pipelines subjected to landslides. Numerical simulation is performed to analyze the change regularity of pipe stresses for the five vulnerability assessment indexes, which are: the distance between pipeline and landslide tail; the thickness of landslide; the inclination angle of landslide; the pipeline length passing through landslide; and the buried depth of pipeline. A pipeline passing through a certain landslide in southwest China was selected as an example to verify the feasibility and effectiveness of this method. This method has practical applicability, but it would need large numbers of examples to better verify its reliability and should be modified accordingly. Also, it only considers the case where the direction of the pipeline is perpendicular to the primary slip direction of the landslide.
Numerical Simulation and Experimental Study of Deep Bed Corn Drying Based on Water Potential
Directory of Open Access Journals (Sweden)
Zhe Liu
2015-01-01
Full Text Available The concept and the model of water potential, which were widely used in agricultural field, have been proved to be beneficial in the application of vacuum drying model and have provided a new way to explore the grain drying model since being introduced to grain drying and storage fields. Aiming to overcome the shortcomings of traditional deep bed drying model, for instance, the application range of this method is narrow and such method does not apply to systems of which pressure would be an influential factor such as vacuum drying system in a way combining with water potential drying model. This study established a numerical simulation system of deep bed corn drying process which has been proved to be effective according to the results of numerical simulation and corresponding experimental investigation and has revealed that desorption and adsorption coexist in deep bed drying.
Directory of Open Access Journals (Sweden)
Mingshun Hu
2017-12-01
Full Text Available Ultrasonic wave testing is a classic Non-destructive testing (NDT method to detect, locate and monitor the crack/fracture in construction materials. However, it is still hard to examine those small abnormal bodies since effective reflected signal from abnormity is usually rather weak. In this paper, a new ultrasound imaging technique, equivalent offset migration (EOM, is studied to demonstrate the feasibility and applicability for detecting concrete cracks. Thus, a complex numerical model along with six small scale flaws was built, and then the ultrasonic wave propagation in concrete was modeled by high order finite difference approximation method. Numerical simulation indicates that 1 there exists a strong scattering phenomenon while ultrasound propagates in concrete with multiple small scatter flaws, and 2 EOM is capable of imaging small flaws in concrete with high resolution and accuracy.
A Novel Machine Learning Strategy Based on Two-Dimensional Numerical Models in Financial Engineering
Directory of Open Access Journals (Sweden)
Qingzhen Xu
2013-01-01
Full Text Available Machine learning is the most commonly used technique to address larger and more complex tasks by analyzing the most relevant information already present in databases. In order to better predict the future trend of the index, this paper proposes a two-dimensional numerical model for machine learning to simulate major U.S. stock market index and uses a nonlinear implicit finite-difference method to find numerical solutions of the two-dimensional simulation model. The proposed machine learning method uses partial differential equations to predict the stock market and can be extensively used to accelerate large-scale data processing on the history database. The experimental results show that the proposed algorithm reduces the prediction error and improves forecasting precision.
Preliminary study on mechanics-based rainfall kinetic energy
Directory of Open Access Journals (Sweden)
Yuan Jiuqin Ms.
2014-09-01
Full Text Available A raindrop impact power observation system was employed to observe the real-time raindrop impact power during a rainfall event and to analyze the corresponding rainfall characteristics. The experiments were conducted at different simulated rainfall intensities. As rainfall intensity increased, the observed impact power increased linearly indicating the power observation system would be satisfactory for characterizing rainfall erosivity. Momentum is the product of mass and velocity (Momentum=MV, which is related to the observed impact power value. Since there is no significant difference between momentum and impact power, observed impact power can represent momentum for different rainfall intensities. The relationship between momentum and the observed impact power provides a convenient way to calculate rainfall kinetic energy. The value of rainfall kinetic energy based on the observed impact power was higher than the classic rainfall kinetic energy. The rainfall impact power based kinetic energy and the classic rainfall kinetic energy showed linear correlation, which indicates that the raindrop impact power observation system can characterize rainfall kinetic energy. The article establishes a preliminary way to calculate rainfall kinetic energy by using the real-time observed momentum, providing a foundation for replacing the traditional methods for estimating kinetic energy of rainstorms.
Prediction Based Energy Balancing Forwarding in Cellular Networks
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Yang Jian-Jun
2017-01-01
Full Text Available In the recent cellular network technologies, relay stations extend cell coverage and enhance signal strength for mobile users. However, busy traffic makes the relay stations in hot area run out of energy quickly. Energy is a very important factor in the forwarding of cellular network since mobile users(cell phones in hot cells often suffer from low throughput due to energy lack problems. In many situations, the energy lack problems take place because the energy loading is not balanced. In this paper, we present a prediction based forwarding algorithm to let a mobile node dynamically select the next relay station with highest potential energy capacity to resume communication. Key to this strategy is that a relay station only maintains three past status, and then it is able to predict the potential energy capacity. Then, the node selects the next hop with potential maximal energy. Moreover, a location based algorithm is developed to let the mobile node figure out the target region in order to avoid flooding. Simulations demonstrate that our approach significantly increase the aggregate throughput and decrease the delay in cellular network environment.
A Review of Element-Based Galerkin Methods for Numerical Weather Prediction
2015-04-01
Holton, J.: An introduction to Dynamic Meteorology, 4th edn. Elsevier Academic Press: Inter- nation Geophysics Series: Vol. 88 (2004) 139. Houze , R.A...231(7), 2741 – 2763 (2012) 189. Kwizak, M., Robert , A.: A semi-implicit scheme for grid point atmospheric models of the prim- itive equations. Mon...for nonlinear conservation laws. SIAM J. Numer. Anal. 26, 30–44 (1989) 291. Tanguay, M., Robert , A., Laprise, R.: A semi-implicit semi-Lagrangian
Numerical modelling of softwood time-dependent behaviour based on microstructure
DEFF Research Database (Denmark)
Engelund, Emil Tang
2010-01-01
by the basic physical mechanism behind the time-dependent behaviour. The mechanism causing time-dependency is thought to be sliding of the microfibrils past each other as a result breaking and re-bonding of hydrogen bonds. This can be incorporated in a numerical model by only allowing time-dependency in shear...... be predicted with the described method of modelling. This is seen by simulating experimental results for both single fibres and tissues in creep and relaxation experiments....
First numerical experiences with overlap fermions based on the Brillouin kernel
Durr, Stephan
2016-01-01
Numerical experiences are reported with overlap fermions which employ the Brillouin action as a kernel. After discussing the dispersion relations of both the kernel and the resulting chiral action, some of the physics features are addressed on quenched backgrounds. We find that the overlap with Brillouin kernel is much better localized than the overlap with Wilson kernel. Also a preliminary account is given of the cost of the formulation, in terms of CPU time and memory.
Corrugated Textile based Triboelectric Generator for Wearable Energy Harvesting
Choi, A. Young; Lee, Chang Jun; Park, Jiwon; Kim, Dogyun; Kim, Youn Tae
2017-03-01
Triboelectric energy harvesting has been applied to various fields, from large-scale power generation to small electronics. Triboelectric energy is generated when certain materials come into frictional contact, e.g., static electricity from rubbing a shoe on a carpet. In particular, textile-based triboelectric energy-harvesting technologies are one of the most promising approaches because they are not only flexible, light, and comfortable but also wearable. Most previous textile-based triboelectric generators (TEGs) generate energy by vertically pressing and rubbing something. However, we propose a corrugated textile-based triboelectric generator (CT-TEG) that can generate energy by stretching. Moreover, the CT-TEG is sewn into a corrugated structure that contains an effective air gap without additional spacers. The resulting CT-TEG can generate considerable energy from various deformations, not only by pressing and rubbing but also by stretching. The maximum output performances of the CT-TEG can reach up to 28.13 V and 2.71 μA with stretching and releasing motions. Additionally, we demonstrate the generation of sufficient energy from various activities of a human body to power about 54 LEDs. These results demonstrate the potential application of CT-TEGs for self-powered systems.
Cohesive Zone Model Based Numerical Analysis of Steel-Concrete Composite Structure Push-Out Tests
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J. P. Lin
2014-01-01
Full Text Available Push-out tests were widely used to determine the shear bearing capacity and shear stiffness of shear connectors in steel-concrete composite structures. The finite element method was one efficient alternative to push-out testing. This paper focused on a simulation analysis of the interface between concrete slabs and steel girder flanges as well as the interface of the shear connectors and the surrounding concrete. A cohesive zone model was used to simulate the tangential sliding and normal separation of the interfaces. Then, a zero-thickness cohesive element was implemented via the user-defined element subroutine UEL in the software ABAQUS, and a multiple broken line mode was used to define the constitutive relations of the cohesive zone. A three-dimensional numerical analysis model was established for push-out testing to analyze the load-displacement curves of the push-out test process, interface relative displacement, and interface stress distribution. This method was found to accurately calculate the shear capacity and shear stiffness of shear connectors. The numerical results showed that the multiple broken lines mode cohesive zone model could describe the nonlinear mechanical behavior of the interface between steel and concrete and that a discontinuous deformation numerical simulation could be implemented.
Wicht, J.; Holme, R. T.; Gastine, T.; Duarte, L.
2016-12-01
We use numerical simulations to model Jupiter's internal dynamo and to predict the information Juno's magnetometer may reveal about the internal magnetic field and dynamics. The simulations were performed with the MHD code MagIC, cover 99% of Jupiter's radius below the one bar level, and use an electrical conductivity profile that includes the metallic inner as well as the molecular outer hydrogen layer. Surface magnetic fields closely resemble known magnetic field models. The flow is dominated by a realistic prograde equatorial jet but lacks multiple mid to high latitude jets which, according to our simulations, seem incompatible with a Jupiter like magnetic field. Using the Juno mission trajectory and assuming an isotropic measurement error of 100 nT we could recover the numerical model field to spheric harmonic degree 18, and secular variation (SV) perhaps to degree 5. The field shows characteristic bands where the equatorial jet reaches down to higher conductivities and promotes a secondary local dynamo effect. The presence of these bands as well as the SV caused by zonal flow advection may offer important clues on the depth of the zonal jets. The form of the spectrum can provide additional information on the general depth of the dynamo region: The numerical simulations suggest that dynamo action starts at the radius where the magnetic Reynolds number, the ratio of Ohmic dissipation time to convective turnover time, exceeds about 50. This roughly agrees with the depth where the magnetic power spectrum is white for spherical harmonics degrees beyond four.
Numerical simulation of failure behavior of granular debris flows based on flume model tests.
Zhou, Jian; Li, Ye-xun; Jia, Min-cai; Li, Cui-na
2013-01-01
In this study, the failure behaviors of debris flows were studied by flume model tests with artificial rainfall and numerical simulations (PFC(3D)). Model tests revealed that grain sizes distribution had profound effects on failure mode, and the failure in slope of medium sand started with cracks at crest and took the form of retrogressive toe sliding failure. With the increase of fine particles in soil, the failure mode of the slopes changed to fluidized flow. The discrete element method PFC(3D) can overcome the hypothesis of the traditional continuous medium mechanic and consider the simple characteristics of particle. Thus, a numerical simulations model considering liquid-solid coupled method has been developed to simulate the debris flow. Comparing the experimental results, the numerical simulation result indicated that the failure mode of the failure of medium sand slope was retrogressive toe sliding, and the failure of fine sand slope was fluidized sliding. The simulation result is consistent with the model test and theoretical analysis, and grain sizes distribution caused different failure behavior of granular debris flows. This research should be a guide to explore the theory of debris flow and to improve the prevention and reduction of debris flow.
A Cell-Based Finite Difference Method for the Numerical Solution of PDEs
Salih, A.; Barron, R. M.; Friedl, J.
2011-11-01
The governing partial differential equations of fluid motion are usually numerically approximated using one of three methods: Finite Difference (FD), Finite Volume (FV) or Finite Element (FE). Finding practical solutions to the governing equations of fluid mechanics is one of the most challenging problems in engineering because these equations, in most cases, form a set of coupled non-linear partial differential equations. In this research, a new cell-centred Finite Difference (CCFD) formulation is developed that is applied in each individual cell of an arbitrary mesh discretizing the solution domain. This feature allows the application of the proposed FD numerical formulation on arbitrary mesh topologies, i.e., structured, unstructured or hybrid meshes. Initially, a simple test case is investigated to illustrate this method. The numerical results are compared with the analytical solution and/or a traditional FD solution. Lastly, two additional test cases are conducted to illustrate the ability of the CCFD method to handle mixed boundary types and its extendibility to other types of elliptic boundary value problems.
Unger, André J. A.
2010-02-01
This work is the first installment in a two-part series, and focuses on the development of a numerical PDE approach to price components of a Bermudan-style callable catastrophe (CAT) bond. The bond is based on two underlying stochastic variables; the PCS index which posts quarterly estimates of industry-wide hurricane losses as well as a single-factor CIR interest rate model for the three-month LIBOR. The aggregate PCS index is analogous to losses claimed under traditional reinsurance in that it is used to specify a reinsurance layer. The proposed CAT bond model contains a Bermudan-style call feature designed to allow the reinsurer to minimize their interest rate risk exposure on making substantial fixed coupon payments using capital from the reinsurance premium. Numerical PDE methods are the fundamental strategy for pricing early-exercise constraints, such as the Bermudan-style call feature, into contingent claim models. Therefore, the objective and unique contribution of this first installment in the two-part series is to develop a formulation and discretization strategy for the proposed CAT bond model utilizing a numerical PDE approach. Object-oriented code design is fundamental to the numerical methods used to aggregate the PCS index, and implement the call feature. Therefore, object-oriented design issues that relate specifically to the development of a numerical PDE approach for the component of the proposed CAT bond model that depends on the PCS index and LIBOR are described here. Formulation, numerical methods and code design issues that relate to aggregating the PCS index and introducing the call option are the subject of the companion paper.
Perspective texture synthesis based on improved energy optimization.
Directory of Open Access Journals (Sweden)
Syed Muhammad Arsalan Bashir
Full Text Available Perspective texture synthesis has great significance in many fields like video editing, scene capturing etc., due to its ability to read and control global feature information. In this paper, we present a novel example-based, specifically energy optimization-based algorithm, to synthesize perspective textures. Energy optimization technique is a pixel-based approach, so it's time-consuming. We improve it from two aspects with the purpose of achieving faster synthesis and high quality. Firstly, we change this pixel-based technique by replacing the pixel computation with a little patch. Secondly, we present a novel technique to accelerate searching nearest neighborhoods in energy optimization. Using k- means clustering technique to build a search tree to accelerate the search. Hence, we make use of principal component analysis (PCA technique to reduce dimensions of input vectors. The high quality results prove that our approach is feasible. Besides, our proposed algorithm needs shorter time relative to other similar methods.
Ahmed, Md. Tusher; Hossain, Md. Tanver; Rahman, Md. Ashiqur
2017-06-01
Energy harvesting technology has the ability to create self-powered electronic systems that do not rely on battery power for their operation. Wind energy can be converted into electricity via a piezoelectric transducer during the air flow over a cylinder. The vortex-induced vibration over the cylinder causes the piezoelectric beam to vibrate. Thus useful electric energy at the range 0.2-0.3V is found which can be useful for self-powering small electronic devices. In the present study, prototypes of micro-energy harvester with a shape of 65 mm × 37 mm × 0.4 mm are developed and tested for airflow over D-shaped bluff body for diameters of 15, 20 and 28mm in an experimental setup consisting of a long wind tunnel of 57cm × 57cm with variable speeds of the motor for different flow velocities and the experimental setup is connected at the downstream where flow velocity is the maximum. Experimental results show that the velocity and induced voltage follows a regular linear pattern. A maximum electrical potential of 140 mV for velocity of 1.1 ms-1 at a bluff body diameter of 15 mm is observed in the energy harvester that can be applied in many practical cases for self-powering electronic devices. The simulation of this energy harvesting phenomena is then simulated using COMSOLE multi-physics. Diameter of the bluff bodies as well as flow velocity and size of cantilever beam are varied and the experimental findings are found to be in good agreement with the simulated ones. The simulations along with the experimental data show the possibility of generating electricity from vortex induced vibration and can be applied in many practical cases for self-powering electronic devices.
A New Hybrid Bathroom System Based on Energy Saving Concept
Directory of Open Access Journals (Sweden)
Cui Bo-wen
2016-01-01
Full Text Available Based on the characteristics of hot water supply in bathroom, this article proposes a new hybrid energy hot water supply system. The programmable logic controller(PLC as the master controller was adopted in this system, which could automatically detect and storage main thermal physical of the system, such as temperature, water level, solar radiation intensity, power consumption and so on. The active thermal utilization technology of solar energy, air-source heat pump technology, solar energy intensive natural ventilation technology and low temperature hot water floor radiant heating technology were organically integrated in this system, which has the advantages of energy conservation and environment protection, high automation, safe and reliable operation, etc. At the same time, it can make good use of electric power cost between on-peak and off-peak, and promote the optimal allocation of power resources and reduce the cost, which can achieve the goal of intelligent control and energy saving.
Market Mechanism Design for Renewable Energy based on Risk Theory
Yang, Wu; Bo, Wang; Jichun, Liu; Wenjiao, Zai; Pingliang, Zeng; Haobo, Shi
2018-02-01
Generation trading between renewable energy and thermal power is an efficient market means for transforming supply structure of electric power into sustainable development pattern. But the trading is hampered by the output fluctuations of renewable energy and the cost differences between renewable energy and thermal power at present. In this paper, the external environmental cost (EEC) is defined and the EEC is introduced into the generation cost. At same time, the incentive functions of renewable energy and low-emission thermal power are designed, which are decreasing functions of EEC. On these bases, for the market risks caused by the random variability of EEC, the decision-making model of generation trading between renewable energy and thermal power is constructed according to the risk theory. The feasibility and effectiveness of the proposed model are verified by simulation results.
Performance of the Dutch Energy Sector based on energy, exergy and Extended Exergy Accounting
Energy Technology Data Exchange (ETDEWEB)
Ptasinski, K.J. [Eindhoven University of Technology (Netherlands). Department of Chemical Engineering; Koymans, M.N. [Statistics Netherlands, Voorburg (Netherlands); Verspagen, H.H.G. [Eindhoven University of Technology (Netherlands). Department of Technology Management
2006-12-15
The performance of the Dutch Energy Sector is analyzed using the Standard Exergy Analysis as well as Extended Exergy Accounting (EEA) method. Performance indicators based on energy, exergy and cumulative exergy consumption (CExC) are evaluated for three subsectors: exploitation, transformation, and distribution of energy. It is shown that performance indicators based on CExC are much lower than those based on energy and exergy concepts. The EEA method is applied for analysis of four branches: cokeries and refineries, refineries, central electricity production, and distribution and decentral electricity production. The EEA method originally proposed by Sciubba is modified by evaluating the cost-to-exergy conversion factor from the monetary value and CExC of the feedstock. It was found that the monetary equivalent of extended exergy is higher than the respective product sales. Finally, it is shown that performance indicators of selected energy branches based on extended exergy are much lower than those based on the CExC. (author)
2-μm numerical analysis of linear-cavity FP structures based on fiber Bragg gratings
Bai, Zhuoya; Yan, Fengping; Zhang, Luna; Bai, Yan; Liu, Shuo; Zhou, Hong; Hou, Yafei; Zhang, Ning
2017-05-01
The linewidth performance of all-fiber, linear-cavity Fabry-Perot structures based on fiber Bragg gratings operating at 2-μm band has been investigated numerically. The output linewidth performance of two symmetrical and asymmetrical cavities has been theoretically studied and comprehensively compared. The numerical analysis is based on the transmission matrix method with the simplified parameters. The simulation results show that cavity lengths, cavity lengths ratio, grating lengths, grating lengths ratio, as well as index modulation depths, affect the output linewidth performance. The tolerance ability of the asymmetrical structure is first proposed and investigated under 1 mm accuracy, and single-frequency output can be realized by properly adjusting the properties of the proposed composite linear cavity structure.
Study on energy saving of subway station based on orthogonal experimental method
Guo, Lei
2017-05-01
With the characteristics of quick, efficient and large amount transport, the subway has become an important way to solve urban traffic congestion. As the subway environment will follow the change of external environment factors such as temperature and load of personnel changes, three-dimensional numerical simulations study is conducted by using CFD software for air distribution of subway platform. The influence of different loads (the supply air temperature and velocity of air condition, personnel load, heat flux of the wall) on the subway platform flow field are also analysed. The orthogonal experiment method is applied to the numerical simulation analysis for human comfort under different parameters. Based on those results, the functional relationship between human comfort and the boundary conditions of the platform is produced by multiple linear regression fitting method, the order of major boundary conditions which affect human comfort is obtained. The above study provides a theoretical basis for the final energy-saving strategies.
Energy-Based Controller Design of Stochastic Magnetic Levitation System
Sun, Weiwei; Wang, Kaili; Nie, Congcong; Xie, Xuejun
2017-01-01
This paper investigates the control problem of magnetic levitation system, in which velocity feedback signal is influenced by stochastic disturbance. Firstly, single-degree-freedom magnetic levitation is regarded as an energy-transform action device. From the view of energy-balance relation, the magnetic levitation system is transformed into port-controlled Hamiltonian system model. Next, based on the Hamiltonian structure, the control law of magnetic levitation system is designed by applying...
Biomass based energy system for a south Indian village
Energy Technology Data Exchange (ETDEWEB)
Ravindranath, N.H.; Chanakya, H.N.
1986-01-01
The biomass resources, existing utilization levels and the efficiency of its use have been analyzed for a South Indian village. A biomass based energy efficient strategy has been devised to meet all the energy needs of the village, including substitution of fuels such as electricity and kerosene used in specific activities. Results indicate that the potential as well as the technologies exist for such substitutions. The proposed strategy will lead to an increase in the efficiency of energy use, reduce human drudgery and make villages more self reliant. 19 references.
Microinstallations Based on Renewable Energy Sources in the Construction Sector
Kurzak, Lucjan
2017-10-01
The focus of this paper is on the status and prognoses of the use of microinstallations based on renewable energy sources to supply heat and power. The technologies that have been important in Europe and Poland for microgeneration of electricity include photovoltaic systems, micro wind turbines and co-generation systems. Solar collectors, heat pumps and biomass have also been used to generate heat. Microinstallations for renewable energy sources represent the initial point and the foundation for the development of micro networks, intelligent networks and the whole prosumer energy sector.
A tandem-based compact dual-energy gamma generator.
Persaud, A; Kwan, J W; Leitner, M; Leung, K-N; Ludewigt, B; Tanaka, N; Waldron, W; Wilde, S; Antolak, A J; Morse, D H; Raber, T
2010-02-01
A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in a compact source design. Preliminary results of monoenergetic gamma production are shown.
Directory of Open Access Journals (Sweden)
Murat Osmanoglu
2013-01-01
Full Text Available We have considered linear partial differential algebraic equations (LPDAEs of the form , which has at least one singular matrix of . We have first introduced a uniform differential time index and a differential space index. The initial conditions and boundary conditions of the given system cannot be prescribed for all components of the solution vector here. To overcome this, we introduced these indexes. Furthermore, differential transform method has been given to solve LPDAEs. We have applied this method to a test problem, and numerical solution of the problem has been compared with analytical solution.
Numerical modeling of photon migration in human neck based on the radiative transport equation
Fujii, Hiroyuki; Nadamoto, Ken; Okada, Eiji; Yamada, Yukio; Hoshi, Yoko; Watanabe, Masao
2016-01-01
Biomedical optical imaging has a possibility of a comprehensive diagnosis of thyroid cancer in conjunction with ultrasound imaging. For improvement of the optical imaging, this study develops a higher order scheme for solving the time-dependent radiative transport equation (RTE) by use of the finite-difference and discrete-ordinate methods. The accuracy and efficiency of the developed scheme are examined by comparison with the analytical solutions of the RTE in homogeneous media. Then, the developed scheme is applied to describing photon migration in the human neck model. The numerical simulations show complex behaviors of photon migration in the human neck model due to multiple diffusive reflection near the trachea.
Directory of Open Access Journals (Sweden)
Orlova K.Y.
2017-01-01
Full Text Available The goal of the presented research is to perform numerical modelling of fuel low-temperature vortex combustion in once-through industrial steam boiler. Full size and scaled-down furnace model created with FIRE 3D software and was used for the research. All geometrical features were observed. The baseline information for the low-temperature vortex furnace process are velocity and temperature of low, upper and burner blast, air-fuel ratio, fuel consumption, coal dust size range. The obtained results are: temperature and velocity three dimensional fields, furnace gases and solid fuel ash particles concentration.
A numerical model for the thermal history of rocks based on confined horizontal fission tracks
DEFF Research Database (Denmark)
Jensen, Peter Klint; Hansen, Kirsten; Kunzendorf, Helmar
1992-01-01
A numerical model for determination of the thermal history of rocks is presented. It is shown that the thermal history may be uniquely determined as a piece-by-piece linear function on the basis of etched confined, horizontal fission track length distributions, their surface densities...... measured in transmitted light are biased favouring short tracks compared with measurements in reflected light. Testing of the model is performed on apatites from a tuffaceous sandstone from Bornholm (Denmark) yielding an estimate of the thermal history for the period of about 280 Ma back in time....
Numerical validation framework for micromechanical simulations based on synchrotron 3D imaging
Buljac, Ante; Shakoor, Modesar; Neggers, Jan; Bernacki, Marc; Bouchard, Pierre-Olivier; Helfen, Lukas; Morgeneyer, Thilo F.; Hild, François
2017-03-01
A combined computational-experimental framework is introduced herein to validate numerical simulations at the microscopic scale. It is exemplified for a flat specimen with central hole made of cast iron and imaged via in-situ synchrotron laminography at micrometer resolution during a tensile test. The region of interest in the reconstructed volume, which is close to the central hole, is analyzed by digital volume correlation (DVC) to measure kinematic fields. Finite element (FE) simulations, which account for the studied material microstructure, are driven by Dirichlet boundary conditions extracted from DVC measurements. Gray level residuals for DVC measurements and FE simulations are assessed for validation purposes.
Lu Liu; Feng Pan; Dingyu Xue
2015-01-01
Fractional-order time-delay system is thought to be a kind of oscillatory complex system which could not be controlled efficaciously so far because it does not have an analytical solution when using inverse Laplace transform. In this paper, a type of fractional-order controller based on numerical inverse Laplace transform algorithm INVLAP was proposed for the mentioned systems by searching for the optimal controller parameters with the objective function of ITAE index due to the verified natu...
Measuring information-based energy and temperature of literary texts
Chang, Mei-Chu; Yang, Albert C.-C.; Eugene Stanley, H.; Peng, C.-K.
2017-02-01
We apply a statistical method, information-based energy, to quantify informative symbolic sequences. To apply this method to literary texts, it is assumed that different words with different occurrence frequencies are at different energy levels, and that the energy-occurrence frequency distribution obeys a Boltzmann distribution. The temperature within the Boltzmann distribution can be an indicator for the author's writing capacity as the repertory of thoughts. The relative temperature of a text is obtained by comparing the energy-occurrence frequency distributions of words collected from one text versus from all texts of the same author. Combining the relative temperature with the Shannon entropy as the text complexity, the information-based energy of the text is defined and can be viewed as a quantitative evaluation of an author's writing performance. We demonstrate the method by analyzing two authors, Shakespeare in English and Jin Yong in Chinese, and find that their well-known works are associated with higher information-based energies. This method can be used to measure the creativity level of a writer's work in linguistics, and can also quantify symbolic sequences in different systems.
Writable electrochemical energy source based on graphene oxide
Wei, Di
2015-10-01
Graphene oxide (GO) was mainly used as raw material for various types of reduced graphene oxide (rGO) as a cost effective method to make graphene like materials. However, applications of its own unique properties such as extraordinary proton conductivity and super-permeability to water were overlooked. Here GO based battery-like planar energy source was demonstrated on arbitrary insulating substrate (e.g. polymer sheet/paper) by coating PEDOT, GO ink and rGO on Ag charge collectors. Energy from such GO battery depends on its length and one unit cell with length of 0.5 cm can generate energy capacity of 30 Ah/L with voltage up to 0.7 V when room temperature ionic liquid (RTIL) is added. With power density up to 0.4 W/cm3 and energy density of 4 Wh/L, GO battery was demonstrated to drive an electrochromic device. This work is the first attempt to generate decent energy using the fast transported water molecules inside GO. It provides very safe energy source that enables new applications otherwise traditional battery technology can not make including building a foldable energy source on paper and platform for futuristic wearable electronics. A disposable energy source made of GO was also written on a plastic glove to demonstrate wearability.
Agent-based modelling of consumer energy choices
Rai, Varun; Henry, Adam Douglas
2016-06-01
Strategies to mitigate global climate change should be grounded in a rigorous understanding of energy systems, particularly the factors that drive energy demand. Agent-based modelling (ABM) is a powerful tool for representing the complexities of energy demand, such as social interactions and spatial constraints. Unlike other approaches for modelling energy demand, ABM is not limited to studying perfectly rational agents or to abstracting micro details into system-level equations. Instead, ABM provides the ability to represent behaviours of energy consumers -- such as individual households -- using a range of theories, and to examine how the interaction of heterogeneous agents at the micro-level produces macro outcomes of importance to the global climate, such as the adoption of low-carbon behaviours and technologies over space and time. We provide an overview of ABM work in the area of consumer energy choices, with a focus on identifying specific ways in which ABM can improve understanding of both fundamental scientific and applied aspects of the demand side of energy to aid the design of better policies and programmes. Future research needs for improving the practice of ABM to better understand energy demand are also discussed.
Pine, G. D.; Christian, J. E.; Mixon, W. R.; Jackson, W. L.
1980-07-01
The procedures and data sources used to develop an energy consumption and system cost data base for use in predicting the market penetration of phosphoric acid fuel cell total energy systems in the nonindustrial building market are described. A computer program was used to simulate the hourly energy requirements of six types of buildings; office buildings; retail stores; hotels and motels; schools; hospitals; and multifamily residences. The simulations were done by using hourly weather tapes for one city in each of the ten Department of Energy administrative regions. Two types of building construction were considered, one for existing buildings and one for new buildings. A fuel cell system combined with electrically driven heat pumps and one combined with a gas boiler and an electrically driven chiller were compared with similar conventional systems. The methods of system simulation, component sizing, and system cost estimation are described for each system.
Numerical modeling of electrical upsetting manufacturing processes based on Forge® environment
Alves, J.; Acevedo, S.; Marie, S.; Adams, B.; Mocellin, K.; Bay, F.
2017-10-01
The present work reviews the latest developments done within Forge®, finite element numerical simulation software for all bulk metal forming processes, to deal with electric processing of materials. We present a complete parallel finite-element coupled Electrical-Thermal-Mechanical model for two-dimensional and three-dimensional electro forming applications. The electro-thermal modeling is considered by sequential-coupling in which the Joule heating term computed from the electric resolution is used as a source term for the thermal problem. For the experimental comparison we use an electric upsetting forming case developed at the Osnabrück University of Applied Sciences. The forming process consists in a closed die hot forging case in which an electric current is passed through the billet to heat it up. At the same time, it is deformed by an applied pressure on the billets end surface. We compare the experimental set-up with 2D and 3D numerical simulations.
Relationship between parallel faults and stress field in rock mass based on numerical simulation
Imai, Y.; Mikada, H.; Goto, T.; Takekawa, J.
2012-12-01
Parallel cracks and faults, caused by earthquakes and crustal deformations, are often observed in various scales from regional to laboratory scales. However, the mechanism of formation of these parallel faults has not been quantitatively clarified, yet. Since the stress field plays a key role to the nucleation of parallel faults, it is fundamentally to investigate the failure and the extension of cracks in a large-scale rock mass (not with a laboratory-scale specimen) due to mechanically loaded stress field. In this study, we developed a numerical simulations code for rock mass failures under different loading conditions, and conducted rock failure experiments using this code. We assumed a numerical rock mass consisting of basalt with a rectangular shape for the model. We also assumed the failure of rock mass in accordance with the Mohr-Coulomb criterion, and the distribution of the initial tensile and compressive strength of rock elements to be the Weibull model. In this study, we use the Hamiltonian Particle Method (HPM), one of the particle methods, to represent large deformation and the destruction of materials. Out simulation results suggest that the confining pressure would have dominant influence for the initiation of parallel faults and their conjugates in compressive conditions. We conclude that the shearing force would provoke the propagation of parallel fractures along the shearing direction, but prevent that of fractures to the conjugate direction.
Directory of Open Access Journals (Sweden)
Dwornik Maciej
2016-01-01
Full Text Available The numerical modelling of coupled mechanical, thermal and hydrogeological processes for a soil levee is presented in the paper. The modelling was performed for a real levee that was built in Poland as a part of the ISMOP project. Only four parameters were changed to build different flood waves: the water level, period of water increase, period of water decrease, and period of low water level after the experiment. Results of numerical modelling shows that it is possible and advisable to calculate simultaneously changes of thermal and hydro-mechanical fields. The presented results show that it is also possible to use thermal sensors in place of more expensive pore pressure sensors, with some limitations. The results of stability analysis show that the levee is less stable when the water level decreases, after which factor of safety decreases significantly. For all flooding wave parameters described in the paper, the levee is very stable and factor of safety variations for any particular stage were not very large.
Nanostructured Mo-based electrode materials for electrochemical energy storage.
Hu, Xianluo; Zhang, Wei; Liu, Xiaoxiao; Mei, Yueni; Huang, Yunhui
2015-04-21
The development of advanced energy storage devices is at the forefront of research geared towards a sustainable future. Nanostructured materials are advantageous in offering huge surface to volume ratios, favorable transport features, and attractive physicochemical properties. They have been extensively explored in various fields of energy storage and conversion. This review is focused largely on the recent progress in nanostructured Mo-based electrode materials including molybdenum oxides (MoO(x), 2 ≤ x ≤ 3), dichalconides (MoX2, X = S, Se), and oxysalts for rechargeable lithium/sodium-ion batteries, Mg batteries, and supercapacitors. Mo-based compounds including MoO2, MoO3, MoO(3-y) (0 energy storage systems because of their unique physicochemical properties, such as conductivity, mechanical and thermal stability, and cyclability. In this review, we aim to provide a systematic summary of the synthesis, modification, and electrochemical performance of nanostructured Mo-based compounds, as well as their energy storage applications in lithium/sodium-ion batteries, Mg batteries, and pseudocapacitors. The relationship between nanoarchitectures and electrochemical performances as well as the related charge-storage mechanism is discussed. Moreover, remarks on the challenges and perspectives of Mo-containing compounds for further development in electrochemical energy storage applications are proposed. This review sheds light on the sustainable development of advanced rechargeable batteries and supercapacitors with nanostructured Mo-based electrode materials.