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Ice monitoring methods were applied for 110 kV and above transmission lines with tangent towers.However,the change in the vertical span is not considered,and a significant difference lies in the tower-conductor structure of 10 kV ...
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Ice monitoring methods were applied for 110 kV and above transmission lines with tangent towers.However,the change in the vertical span is not considered,and a significant difference lies in the tower-conductor structure of 10 kV transmission lines.For this reason,a proposal is made about the ice monitoring method for the 10 kV transmission line with tangent tower in alpine landform,which includes the ice monitoring system based on pressure measurement and corresponding equivalent ice thickness calculating methods.Different methods calculate the vertical span under different height difference coefficients.A finite element simulation model and a simulated ice load experiment system are established based on real conductors and insulators.Experiments and simulations under four simulated terrains are conducted within 2.5–20 mm ice thickness range.The comparison is made between this method and the method without considering the change in vertical span.The results show that the two methods are consistent and the relative errors are lower than�4%in simulation and�10%in experiment when the height difference coefficient is 0.When it is not 0,the relative errors of this method fall between t0.38%and t6.78%in simulation and−6.40%to t6.60%in experiment,while the relative errors of the method without considering the change in vertical span ranges between−11.13%and−20.23%in simulation and−11.65%to−23.20%in experiment.
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Diagnosis of fluids is extremely significant at high temperatures and high pressures.As an advanced imaging technique,high-energy proton radiography has great potential for application to the diagnosis of high-density fluids.In hi...
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Diagnosis of fluids is extremely significant at high temperatures and high pressures.As an advanced imaging technique,high-energy proton radiography has great potential for application to the diagnosis of high-density fluids.In high-energy proton radiography,an angular collimator can control the proton flux and thus enable material diagnosis and reconstruction of density.In this paper,we propose a multimaterial diagnostic method using angular collimators.The method is verified by reconstructing the density distribution from the proton flux obtained via theoretical calculations and numerical simulations.We simulate a 20 GeV proton imaging system using the Geant4 software toolkit and obtain the characteristic parameters of single-material objects.We design several concentric spherical objects to verify the method.We discuss its application to detonation tests.The results show that this method can determine the material and boundary information about each component of a multi-material object.Thus,it can be used to diagnose a mixed material and reconstruct densities in a detonation.
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The neutron-induced reaction data on unstable nuclei is an important basic data for nuclear science and engineering,and is one of the key data in nuclear astrophysics.The key point of the evaluated data obtained is the evaluated m...
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The neutron-induced reaction data on unstable nuclei is an important basic data for nuclear science and engineering,and is one of the key data in nuclear astrophysics.The key point of the evaluated data obtained is the evaluated method.Based on the research results of neutroninduced reaction data on stable nuclei and the evaluated method,the evaluated method of neutrorrinduced reaction data on unstable nuclei is given by use nuclear reaction theoretical models.
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Meshless or mesh-free (or shorten as MFree) methods have been proposed and achieved remarkable progress over the past few years. The idea of combining MFree methods with other existing numerical techniques such as the finite eleme...
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Meshless or mesh-free (or shorten as MFree) methods have been proposed and achieved remarkable progress over the past few years. The idea of combining MFree methods with other existing numerical techniques such as the finite element method (FEM) and the boundary element method (BEM), is naturally of great interest in many practical applications. However, the shape functions used in some MFree methods do not have the Kronecker delta function property. In order to satisfy the combined conditions of displacement compatibility, two numerical techniques, using the hybrid displacement shape function and the modified variational form, are developed and discussed in this paper. In the first technique, the original MFree shape functions are modified to the hybrid forms that possess the Kronecker delta function property. In the second technique, the displacement compatibility is satisfied via a modified variational form based on the Lagrange multiplier method. Formulations of several coupled methods are presented. Numerical examples are presented to demonstrate the effectiveness of the present coupling methods.
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This paper is concerned with the characteristics of a tracking differentiator(TD)in arranging transition process for the physical system.In order to overcome disadvantages of linear TD(LTD)in practice,a novel variable parameter li...
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This paper is concerned with the characteristics of a tracking differentiator(TD)in arranging transition process for the physical system.In order to overcome disadvantages of linear TD(LTD)in practice,a novel variable parameter linear tracking differentiator(VLTD)is proposed.By designing the speediness factor as a function of the tracking error,the VLTD can track a large range of set values with reasonable speed and acceleration.Analysis shows that VLTD can converge to its set value under certain conditions.Meanwhile,the speed and acceleration bounds are added to the VLTD,which guarantees that the proposed transition signal really plays a transitional role.The numerical simulation results emphasize necessity for adding speed and acceleration bounds to the VLTD.By comparing VLTD with the nonlinear TD(NLTD)in the simulations and experiments,VLTD can achieve almost the same performance as the NLTD while it is easier to be implemented.
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In this paper we consider the numerical method of characteristics for the numerical solution of initial value problems (IVPs) for quasilinear hyperbolic Partial Differential Equations, as well as the difference scheme Central Time...
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In this paper we consider the numerical method of characteristics for the numerical solution of initial value problems (IVPs) for quasilinear hyperbolic Partial Differential Equations, as well as the difference scheme Central Time Central Space (CTCS), Crank-Nicolson scheme, ω scheme and the method of characteristics for the numerical solution of initial and boundary value prob-lems for the one-dimension homogeneous wave equation. The initial deriva-tive condition is approximated by different second order difference quotients in order to examine which gives more accurate numerical results. The local truncation error, consistency and stability of the difference schemes CTCS, Crank-Nicolson and ω are also considered.
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鉴于火电机组直接空冷技术的广泛运用，针对托电三、四期直接空冷系统夏季出现的环境温度高、风向多变、热风回流等问题，对其产生原因、应对措施以及运行中调整方法进行了分析探讨。
Given the extensive use of the thermal power units direct ai...
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鉴于火电机组直接空冷技术的广泛运用，针对托电三、四期直接空冷系统夏季出现的环境温度高、风向多变、热风回流等问题，对其产生原因、应对措施以及运行中调整方法进行了分析探讨。
Given the extensive use of the thermal power units direct air-cooled technology for direct air cooling system of Tuoketuo power unit three and four in summer about ambie
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Solar forecasting is of great importance for ensuring safe and stable operations of the power system with increased solar power integration,thus numerous models have been presented and reviewed to predict solar irradiance and powe...
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Solar forecasting is of great importance for ensuring safe and stable operations of the power system with increased solar power integration,thus numerous models have been presented and reviewed to predict solar irradiance and power forecasting in the past decade.Nevertheless,few studies take into account the temporal and spatial resolutions along with specific characteristics of the models.Therefore,this paper aims to demonstrate a comprehensive and systematic review to further solve these problems.First,five classifications and seven pre-processing methods of solar forecasting data are systematically reviewed,which are significant in improving forecasting accuracy.Then,various methods utilized in solar irradiance and power forecasting are thoroughly summarized and discussed,in which 128 algorithms are elaborated in tables in the light of input variables,temporal resolution,spatial resolution,forecast variables,metrics,and characteristics for a more fair and comprehensive comparison.Moreover,they are categorized into four groups,namely,statistical,physical,hybrid,and others with relevant application conditions and features.Meanwhile,six categories,along with 30 evaluation criteria,are summarized to clarify the major purposes/applicability of the different methods.The prominent merit of this study is that a total of seven perspectives and trends for further research in solar forecasting are identified,which aim to help readers more effectively utilize these approaches for future in-depth research.
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