Rapid Calculation Method Research Articles

Magnetic Circuit Modeling and Analysis of Unilateral Axle-Counting Sensor

The unilateral axle-counting sensor, as a new type of axle-counting device, is gradually substituting other axle counters owing to its simple structure and great performance, which lead to an excellent application prospect. In this paper, we analyze the working principle of this sensor and establish an equivalent magnetic circuit model based on the sensor structure characteristics and its spatial relation with the track and wheel. In addition, we propose a rapid calculation method for magnetic circuits based on the division of the magnetic flux area according to the magnetic flux distribution characteristics of the sensor and provide the calculation expressions of reluctance for each area; furthermore, we calculate the induction electromotive force generated in the induction coils. Using 3-D finite-element method and the actual measurement of the induction electromotive force, the correctness and rapidity of the magnetic circuit model and the method of calculating the induction electromotive force are proved.

Rapid calculation method for estimating static and dynamic performances of closed hydrostatic guideways

PurposeThe purpose of this paper is to establish a simplified model of the closed hydrostatic guideway for the rapid analysis of static and dynamic characteristics. Further, the influence of compressibility and dynamic frequency are taken into consideration in the new dynamic model.Design/methodology/approachThe new model is based on the second kind of Lagrange equation. In this model, the closed hydrostatic guideway is supported by 12 pads, and each oil pad is equivalent to a nonlinear spring-damper system. The equivalent spring coefficient and damper coefficient of the oil pad are extracted by the three different equivalent methods. Finally, the validation experiments of step load response and dynamic stiffness are conducted on a hydrostatic guideway.FindingsFor solving the step response, the linear spring-damper model and the nonlinear spring-damper Model 1 are better than the nonlinear spring-damper Model 2. The accuracy of the three methods are very high for static stiffness calculation. For the calculation of dynamic stiffness, the nonlinear spring-damper Model 2 is better than the nonlinear spring-damper Model 1. The linear spring-damper model has low precision for dynamic stiffness calculation, especially at high frequency. The accuracy of the new model is validated by experiments.Originality/valueThe equivalent method of nonlinear spring-damper system has higher accuracy. Different equivalent methods should be adopted for different load types. The computational speeds of the new dynamic model with the three methods are much better than finite element method (about ten times).

Multi-objective optimization of the aerodynamic shape of a long-range guided rocket

The parameter values associated with the optimal aerodynamic shape of a long-range guided rocket (LGR) are different from those of an unguided rocket because the shapes and design objectives are different. Here we establish a multi-objective optimization model of the aerodynamic shape of an LGR for the purpose. Moreover, a rapid aerodynamic calculation method is used, which is much more efficient than wind-tunnel tests or computational fluid dynamics (CFD). Previously, the aerodynamic shape of an unguided rocket would be optimized by identifying one parameter as a single objective and regarding the others as constraints. Here, we use version II of the non-dominated sorting genetic algorithm (NSGA-II) and the real-coding genetic algorithm (RGA) to solve this multi-objective optimization problem (MOP). The results obtained by the two algorithms show an improved lift/drag ratio of the LGR with optimal aerodynamic shape, better maneuverability, and acceptable stability. Furthermore, the optimum and original schemes are calculated using CFD, and the pressure contours show that the results are qualitatively correct. This method can be used to design the optimal aerodynamic shape of this type of rocket.

Notch stress intensity factors under mixed mode loadings: an overview of recent advanced methods for rapid calculation

Recently some methods for the rapid calculation of notch stress intensity factors (NSIFs) have been developed and three of them are compared in this work. First, the criteria proposed by Lazzarin et al. and Treifi et al. have been reviewed. The former is based on the calculation of the mean value of SED on two different control volume (characterized by two different radius values) centred at the stress singularity point, whereas the latter takes advantage of the strain energy density averaged within two control volumes (semi-circular sector) centred at the notch tip. Then, a new method based on the evaluation of the total and deviatoric SED averaged in a single control volume has been proposed. Finally, plate specimens weakened by different notch geometries have been subjected to the application of the above mentioned methods and the obtained values of the NSIFs have been compared with those derived according to Gross and Mendelson.

Rapid Calculation Method Study and Realization for Wind Load of Ship-Borne Satellite Antenna

For antennas working in exposed environment, wind load is one of the main loads that must be taken into consideration. Wind load can not only directly impact on the structural strength of antenna, but also make actuating shaft of servo system bear wind torque disturbance which may indirectly affect the tracking accuracy of antenna servo system. This paper completed numerical computation on the wind loads of antenna at different wind speeds, angles of wind approach and angles of pitch based on method of computational fluid mechanics, hence the velocity fluid fields, pressure distribution on reflecting surface and moments of antenna under various posture situations were obtained and a sample database has been formed. According to the weather and ship navigation situation, rapid calculation of the wind load and moment born by antenna realized through ternary three-order curvilinear interpolation algorithm can effectively solve the problem of rapidly calculating the wind load of ship-borne satellite antenna. Moreover, with the sample database formed according to the images and moment data obtained from computation, the wind loads and moment parameters of antenna under all working conditions were obtained through ternary three-order interpolation algorithm, so as to realize the rapid calculation method for the wind loads of antenna under all working conditions.

Extensive Accuracy Test of the Force-Field-Based Quasichemical Method PAC–MAC

We present a comprehensive evaluation of the recently developed pair configuration to molecular activity coefficient (PAC–MAC) method. PAC–MAC is a force-field-based quasichemical method for rapid calculation of binary phase diagrams. The accuracy of the method is tested by comparing the calculated excess mixing free energy with experimental data for 1092 binary mixtures. The root mean squared error (RMSE) is shown to be 0.15 kBT. Furthermore, a comparison with UNIFAC and molecular simulations is performed. UNIFAC shows a significantly higher accuracy (RMSE: 0.07 kBT), whereas molecular simulations lead to comparable results. The accuracy of both molecular simulations as well as PAC–MAC depends highly on the used force field. The binary parameters of UNIFAC are optimized using experimental miscibility data, whereas the force field parameters are not. Therefore, a better performance of UNIFAC is expected. A concise data set shows the capacity of PAC–MAC in predicting results obtained using Monte Carlo simu...

A hypersonic aeroheating calculation method based on inviscid outer edge of boundary layer parameters

This article presents a rapid and accurate aeroheating calculation method for hypersonic vehicles. The main innovation is combining accurate of numerical method with efficient of engineering method, which makes aeroheating simulation more precise and faster. Based on the Prandtl boundary layer theory, the entire flow field is divided into inviscid and viscid flow at the outer edge of the boundary layer. The parameters at the outer edge of the boundary layer are numerically calculated from assuming inviscid flow. The thermodynamic parameters of constant-volume specific heat, constant-pressure specific heat and the specific heat ratio are calculated, the streamlines on the vehicle surface are derived and the heat flux is then obtained. The results of the double cone show that at the 0° and 10° angle of attack, the method of aeroheating calculation based on inviscid outer edge of boundary layer parameters reproduces the experimental data better than the engineering method. Also the proposed simulation results of the flight vehicle reproduce the viscid numerical results well. Hence, this method provides a promising way to overcome the high cost of numerical calculation and improves the precision.

A Rapid Online Calculation Method of Three-dimensional Plastic Deformation in Strip Rolling

Three-dimensional strip plastic deformation model is a key part of shape setup model in hot rolling. The numerical efficiency, accuracy and stability of the method are the main factors that may restrict its online application. Considering the theoretical limitations of existing models, basic equations include equilibrium equations with the effect of shear stress, constitutive equations based on incremental theory, and lubricated friction with the respective coefficients of friction at longitudinal and transverse direction. After normalization of parameters and the asymptotic analysis, the strip plastic deformation model is established, and solved by finite volume method and BICGSTAB algorithm to get the transverse distribution of rolling force of each stand. Compared to the finite element model established by ANSYS software, the new model has reliable results and a short computation time of 31 milliseconds, which show its feasibility of online application.

General Equivalent Magnetic Circuit Calculation Software Based on the Quasi-Newton Algorithm

Equivalent magnetic circuit method is a rapid calculation method used in magnetic circuit simulation. But for a long time this method can’t be used widely because the algorithm is not general and there is no commercial software developed for this method. In this paper, general software for magnetic circuit calculation was developed using LabVIEW language. Quasi-Newton algorithm was used in solving nonlinear Kirchhoff equation of magnetic circuit in this software. The project file in this software can be shared freely in different calculations. This software is expected to save the time-cost in the design of new product.

A rapid and accurate method for calculation of capillary pressure from centrifuge data

Abstract Centrifugation technique is among various methods for rock capillary pressure measurement. In this method, capillary pressure data is not directly measured and it should be calculated from production data. Calculation of capillary pressure data needs conversion of the measured fluid productions to the local saturation values. Considering frequent use of the conventional centrifuge method in the industry, an accurate and rapid technique is highly demanded. Several interpretation techniques have been reported in the literature. Simple methods can be found with less accuracy, while accurate methods usually require time consuming analysis. In this paper, a simple method is proposed based on a semi-analytical solution for calculation of local saturation from experimental data. In this method fundamental centrifuge equation, which is a Voltera equation, is converted by Laplace transformation. Inverse Laplace transformation is performed assuming a sub-polynomial equation for each segment of average saturation ( S ¯ ). The performance of the proposed method is evaluated using two theoretical functions for capillary pressure. The results obtained by new method are compared with the results from the available methods in the literature.

Research of an improved interruption model coupling air blast for the low voltage circuit breaker

Aimed to provide a more close-to-reality and rapid calculation method for optimization design of low voltage circuit breaker with complex mechanism, an interruption model is constructed, which can describe the coupling of air blast process with arc model, complex mechanical movement, magnetic field, and electric circuit. The model is based on the non-stationary gas conservation equations, and considers the influence of the chamber structure on the gas dynamics. To realize the interaction between the arc movement and the gas flow simply, on the one hand, the moving electric arc is deemed an energy input source of the chamber gas. On the other hand, the movement equation of the arc considering action of the gas flow is built. With this model, the general principle of the chamber gas flow, arc voltage and current during the interruption process of an actual breaker are calculated and compared with the experiment results. As an application, the influence of the chamber vent size on the arc movement is studied with the model as well.

A Local-to-Global Dimensional Error Calculation Framework for the Riveted Assembly Using Finite-Element Analysis

Abstract Mechanical structures of large-scale antennas are sheet metals connected by thousands of rivets. The antenna dimensional error after riveting often violates the limit allowed. The prediction of the global dimensional error induced by many rivet connections requires a rapid and accurate assembly deformation calculation method. Main process parameters of these local rivet connections are the local connection dimension, material property, local clamp position, rivet upsetting direction, and the hammer time-to-displacement impact, except for the riveting sequence. We neglect the process parameter uncertainties and consider that the main riveting parameters equate to a dynamic finite-element (FE) model of single rivet connection. The dynamic FE analysis result yields an inherent strain database for the riveted local parts. Then, we propose an iterative loop of static FE analyses for the global structure taking the inherent strain database and possible former static FE analysis result as the boundary conditions. The loop forms a local-to-global framework. Two examples are involved through the framework representation and realistic application. Framework advantages include: (1) a good balance between the cost and precision of dimensional error calculation; (2) the sequence simulation of all the riveting operations; and (3) supporting the further assembly process optimization to reduce the global dimensional error of the assembly with thousands of rivets.

The Rapid Engineering Aero-Heating Calculation Method for Hypersonic Vehicles

The rapid engineering aero-heating calculation method for hypersonic vehicles is established for the question of computational efficiency during conceptual design stage. First the pressure distribution along vehicle’s surface is calculated by modified Newtonian theory. Secondly, the streamline along the surface is calculated with Newtonian steepest decent concept. Then by using reference enthalpy method, the heat flux on the surface is given. Finally, the heat flux on the surfaces of blunted cone, lifting body and wave-rider vehicle is calculated The analysis result shows the method used in this paper is fit for hypersonic vehicles, and can satisfies the aero-heating calculation during conceptual design stage in both efficiency and accuracy.

CO<sub>2</sub> 배출량 평가를 위한 BIM 모델 구축 최적화 방안

The World Meteorological Organization and United Nations Environment Programme (UNEP) have officially declared that carbon dioxide is the main cause in global warming. Architectural structures are primarily responsible for emissions, and in order to reduce their emissions, it is essential to introduce rapid and accurate calculation methods during the design phase of construction. The emissions of building components can be calculated by applying the correction factors derived in the design phase directly to standardized data based on building information modeling (BIM). With the objective to support energy-efficient building design, this study had the goal of investigating the accuracy of BIM-based quantity calculation, thereby focusing on a BIM library and modeling, and presenting the results as user guidelines to allow BIM data to be used for the rapid and objective analysis and verification of emissions. To this end, we studied the applicability of BIM-based quantity calculation on the basis of the information for major materials presented in previous studies related to emission evaluation. Additionally, an optimal BIM modeling method is presented based on the results of an analytical comparison of the calculated quantities after applying the BIM data generation methods for different combinations of architectural components to a multi-family residence. The results of this study are expected to be of great help in designing low-carbon buildings by predicting the emissions of building components in a BIM-based design phase.

Risk calculation method for complex engineering system

This paper presents a rapid and simple risk calculation method for large and complex engineering systems, the simulated maximum entropy method (SMEM), which is based on integration of the advantages of the Monte Carlo and maximum entropy methods, thus avoiding the shortcoming of the slow convergence rate of the Monte Carlo method in risk calculation. Application of SMEM in the calculation of reservoir flood discharge risk shows that this method can make full use of the known information under the same conditions and obtain the corresponding probability distribution and the risk value. It not only greatly improves the speed, compared with the Monte Carlo method, but also provides a new approach for the risk calculation in large and complex engineering systems.

Cross-circularly polarized two-exciton states in one to three dimensions.

Biexciton and two-exciton dissociated states of Frenkel-type excitons are studied theoretically using an exciton tight-binding (TB) model including a polarization degree of freedom. Because the biexciton consists of two cross-circularly polarized excitons, an on-site interaction (V) between the two excitons should be considered in addition to a nearest-neighbor two-exciton attractive interaction (δ). Although there are an infinitely large number of combinations of V and δ providing the observed binding energy of a biexciton, the wave function of the biexciton and two-exciton dissociated states is nearly independent of these parameter sets. This means that all the two-exciton states are uniquely determined from the exciton TB model. There are a spatially symmetric and an antisymmetric biexciton state for a one-dimensional (1D) lattice and two symmetric and one antisymmetric biexciton states at most for two- (2D) and three-dimensional (3D) lattices. In contrast, when the polarization degree of freedom is ignored, there is one biexciton state for 1D, 2D, and 3D lattices. For this study, a rapid and memory-saving calculation method for two-exciton states is extended to include the polarization degree of freedom.

Distribution assessment and quantification of counterfeit melamine in powdered milk by NIR imaging methods

This paper presents a rapid calculation method for the imaging process in the identification and quantification of prohibited additives in milk. Data abstraction methods such as principal component analysis (PCA), classical least squares regression (CLS), and alternative least squares regression (ALS) were used. Different multivariate calculations provided possibilities of quantifying near-infrared (NIR) spectral data cube obtained from the surface of the complex mixture. The results of principal component decomposition confirmed that sample mixture identification is feasible using the PCA–CCI methods. Subsequently, CLSI was used for the direct quantitative analysis of the specific component. Behaving more conveniently than PLS without modeling, CLSI can obtain quantitative information as that melamine generally distribute at the low concentration range of 0–0.5w/w. Moreover, ALSI can quantify the target component with higher accuracy than CLSI. Standard error of residue to predicted value is 0.0838. Lack of fit is 0.0841. Explanation of variables in the mixture is 99.30%, illustrating that the selective lack of rank is insignificant. Obviously, the most intuitive distribution images are constructed by ALSI among four imaging methods.

Rapid interpolation calculation method based on physical rules with MCNP simulation results

Rapid interpolation calculation method based on physical rules with MCNP simulation results

Electromechanical Battery EMB Mass Minimization taking into Account its Electrical Machines Rotor Energy

Abstract In this paper the electromechanical battery (EMB) with synchronous machine is described. Theoretically, if electrical machines rotor stored energy is known, it is possible to reduce the flywheel mass of electromechanical battery. For example, the efficiency of energy recovery (kilowatt-hours out versus kilowatthours in) in nowadays appliances exceeds 95 % which is considerably better than of any electrochemical battery, such as lead-acid battery. For the rotor stored energy amount calculation, it is necessary to find all geometrical dimensions of the electrical machine. To achieve this goal the iterative calculation method was used. Electromechanical battery mass was analyzed as a discharge process rotation speed function. Taking into account the rotor stored energy, we can increase the minimum rotation speed thus reducing the electrical machine mass and increasing the flywheel mass, which provides EMB cost reduction. Additionally, the possibilities of using numerical approximation calculations of magnetization curves are discussed. Each iteration of numerical application necessary for the method for rapid calculation is essential when calculating the field problems. Nowadays there are a lot of computer added design programs for electromagnetic field calculation in different types of applications, electrical machines and apparatus. For the electromagnetic field calculation process some more commonly used magnetization curve approximation methods are described, and the machine calculation time is tested for different numbers of calculations.

A closed form solution method for rapid calculation of guided wave dispersion curves for pipes

Guided wave inspection is a fast growing technology for screening pipelines for corrosion. The technique is capable of inspecting tens of metres from a single test location and examining otherwise inaccessible regions of pipeline such as cased road crossings. However, enhancements to the technique are needed if inspections are to be transformed from a screening procedure to a more quantitative assessment of the condition of the pipeline. A rapid calculation procedure to determine the dispersion curves for guided wave modes is important if enhancements are to be automatically incorporated into the technique. Commercial code for dispersion curve calculation is available but it is proprietary and typically uses an iterative procedure to calculate curves which can be unreliable and slow. Other methods for calculating dispersion curves have been published including semi-analytical finite element solutions but these require extensive programming. In this paper, a closed form solution based on known trigonometric behaviour in the circumferential and axial directions and a standard polynomial solution through the thickness is presented. The method allows rapid computation of dispersion curves for typical guided wave inspection scenarios with minimal programming required. In addition, a tracing algorithm is also presented which allows the computed points to be joined to form curves and therefore fully identify the dispersive behaviour of each wave mode. The new method has been successfully verified against the well-established software, Disperse®, for a range of pipe sizes, materials and frequencies typical to guided wave inspection.