Mathematic model of the FX correlator of the Chinese VLBI network and its application

2001 ◽  
Author(s):  
Weimin Zheng ◽  
Xiuzhong Zhang ◽  
Fengchun Shu
Keyword(s):  
Mathematic Model ◽  
Chinese Vlbi Network

A Calculation real abundance of gaseous elements of the comet PanSTARRS C/2011 S4

2020 ◽  
Vol 18 (45) ◽  
pp. 21-31
Author(s):  
Salman Zaidan Khalaf ◽  
Khaleel Abrahim ◽  
Imad Kassar Akeab
Keyword(s):  
Solar Wind ◽  
Physical Properties ◽  
Atomic Number ◽  
Mathematic Model ◽  
Emission Energy ◽  
X Ray ◽  
The Real

    X-ray emission contains some of the gaseous properties is produced when the particles of the solar wind strike the atmosphere of comet ISON and PanSTARRS Comets. The data collected with NASA Chandra X-ray Observatory of the two comets, C/2012 S1 (also known as Comet ISON) and C/2011 S4 (Comet PanSTARRS) are used in this study.    The real abundance of the observed X-ray spectrum elements has been extracted by a new simple mathematic model. The study found some physical properties of these elements in the comet’s gas such as a relationship between the abundance with emitted energy. The elements that have emission energy (2500-6800) eV, have abundance (0.1-0.15) %, while the elements that have emission energy (850-2500) eV and (6800-9250) eV have abundance (0.2-0.3) %.    The relation between interacted energy and atomic number is form two sets.  The interacted energy of each element is increased as the atomic number increased. This case has been seen in both comets

A Novel Control Scheme for PWM Boost Converter based on Sliding Mode Control using Particle Swarm Optimization

2020 ◽  
Vol 14 ◽  
Author(s):  
Gang Liu ◽  
Dong Qiu ◽  
Xiuru Wang ◽  
Ke Zhang ◽  
Huafeng Huang ◽  
...  
Keyword(s):  
Particle Swarm Optimization ◽  
Steady State ◽  
Sliding Mode ◽  
Particle Swarm ◽  
Mathematic Model ◽  
Absolute Error ◽  
Boost Converter ◽  
Sliding Mode Controller ◽  
Swarm Optimization ◽  
Steady State Performance

Background: The PWM Boost converter is a strongly nonlinear discrete system, especially when the input voltage or load varies widely, therefore, tuning the control parameters of which is a challenge work. Objective: In order to overcome the issues, particle swarm optimization (PSO) is employed for tuning the parameters of a sliding mode controller of a boost converter. Methods: Based on the analysis of the Boost converter model and its non-linear characteristics, a mathematic model of a boost converter with a sliding mode controller is built firstly. Then, the parameters of the Boost controller are adjusted based on the integrated time and absolute error (ITAE), integral square error (ISE) and integrated absolute error (IAE) indexes by PSO. Results: Simulation verification was performed, and the results show that the controllers tuned by the three indexes all have excellent robust stability. Conclusion: The controllers tuned by ITAE and ISE indexes have excellent steady-state performance, but the overshoot is large during the startup. The controller tuned by IAE index has better startup performance and slightly worse steady-state performance.

scholarly journals Microstructure Dependence of Effective Thermal Conductivity of EB-PVD TBCs

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1838
Author(s):  
Shi-Yi Qiu ◽  
Chen-Wu Wu ◽  
Chen-Guang Huang ◽  
Yue Ma ◽  
Hong-Bo Guo
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Stress ◽  
Effective Thermal Conductivity ◽  
Thermal Insulation ◽  
Inclination Angle ◽  
Physical Vapor Deposition ◽  
Thermal Contact ◽  
Mathematic Model ◽  
Columnar Structure ◽  
Structural Parameter

Microstructure dependence of effective thermal conductivity of the coating was investigated to optimize the thermal insulation of columnar structure electron beam physical vapor deposition (EB-PVD coating), considering constraints by mechanical stress. First, a three-dimensional finite element model of multiple columnar structure was established to involve thermal contact resistance across the interfaces between the adjacent columnar structures. Then, the mathematical formula of each structural parameter was derived to demonstrate the numerical outcome and predict the effective thermal conductivity. After that, the heat conduction characteristics of the columnar structured coating was analyzed to reveal the dependence of the effective thermal conductivity of the thermal barrier coatings (TBCs) on its microstructure characteristics, including the column diameter, the thickness of coating, the ratio of the height of fine column to coarse column and the inclination angle of columns. Finally, the influence of each microstructural parameter on the mechanical stress of the TBCs was studied by a mathematic model, and the optimization of the inclination angle was proposed, considering the thermal insulation and mechanical stress of the coating.

A Mathematic Model Based on Unstructured Mesh for Simulating Ice Accretion on Aircraft

2019 ◽  
Author(s):  
Ningli Chen ◽  
Yaping Hu ◽  
Honghu Ji ◽  
Yongqing Yuan ◽  
Guangzhou Cao
Keyword(s):  
Unstructured Mesh ◽  
Mathematic Model ◽  
Ice Accretion ◽  
Model Based

The Microstructure and Formability Study on DP Steel of Lightweight Automobile

2011 ◽  
Vol 704-705 ◽  
pp. 1465-1472
Author(s):  
Jin Wu ◽  
Da Sen Bi ◽  
Liang Chu ◽  
Jian Zhang ◽  
Yun Tao Li
Keyword(s):  
Mechanical Property ◽  
Work Hardening ◽  
High Strength Steel ◽  
High Strength ◽  
Mathematic Model ◽  
Theoretical Research ◽  
Forming Limit ◽  
Strain Hardening Exponent ◽  
Dp Steel ◽  
Better Than

Dual phase (DP) steel is a high strength steel for auto-panel. In this paper, mechanical property, forming ability, baked-hardening and work hardening properties of high strength steel DP450 are studied by experiments, and compared with those of steel MS6000.And theoretical research on predicting the forming limit of steel DP450 by the NADDRG model. The established mathematic model for relativity is of practical usefulness. Experimental results reveal that the yield strength of steel DP450 is about 7.2% lower than the MS6000,and the break strength increases by 18.9%,while the elongation increases by 19%.The strain hardening exponent of steel DP450 are superior to those of MS6000.The results show that mechanical property of high strength steel DP450 is better than that of MS6000,while forming ability of DP450 is not lower than that of MS6000.And baked-hardening and work hardening properties of steel DP450 are better than those of MS6000.The steel sheet DP450 owned a good forming ability.

The Mathematical Model of Welding Process Comparative Study of Identification Method

2012 ◽  
Vol 472-475 ◽  
pp. 2241-2244 ◽  
Author(s):  
Jun Feng Wu ◽  
Jing Huang
Keyword(s):  
Weld Pool ◽  
Academic Research ◽  
Welding Process ◽  
Least Square Method ◽  
Mathematic Model ◽  
Least Square ◽  
Complex Object ◽  
Strong Nonlinearity ◽  
Area Method ◽  
Pulsed Gtaw

The dynamic process of the weld pool is a high complex object with strong nonlinearity, mult-variable coupling and a mount of stochastic and uncertain factors. It is very difficult to obtain an analysis mathematic model of weld pool dynamics. Pulsed Gas Tungsten Arc Welding (GTAW) is an important metal’s welding technology, which has been widely applied in the aerospace and manufacturing areas. Therefore, the dynamic characteristic of the welding process has always been hot and difficult in the field of academic research and engineering applications. In order to solve the difficulties of modeling and controlling of nonlinear system, this paper investigates the dynamic characters of the pulsed GTAW from the classic control systems. It obtains the SISO transfer function model by the area method and least square method. The results of simulation experiment show that the area method is better between the two methods.

Numerical Study on the Effect of Inner Tube Position on Heat Transfer Process in Self-Recuperative Radiant Tube

2011 ◽  
Vol 228-229 ◽  
pp. 676-680 ◽  
Author(s):  
Ye Tian ◽  
Xun Liang Liu ◽  
Zhi Wen
Keyword(s):  
Heat Transfer ◽  
Transfer Process ◽  
Numerical Study ◽  
Flame Temperature ◽  
Three Dimensional ◽  
Mathematic Model ◽  
Heat Transfer Process ◽  
Bulk Temperature ◽  
Radiant Tube ◽  
Peak Value

A three-dimensional mathematic model is developed for a 100kw single-end recuperative radiant tube and the simulation is performed with the CFD software FLUENT. Also it is used to investigate the effect of distance between combustion chamber exit and inner tube on heat transfer process. The results suggest that the peak value of combustion flame temperature drops along with the increasing of distance, which leads to low NOX discharging. Also radiant tube surface bulk temperature decreases, which causes radiant tube heating performance losses.

Compensation of the Nonlinear Effect on Anelectro Hydrostatic Cylinder Driver for the Transit and Rotating Motion Using Bilinear System

2014 ◽  
Vol 875-877 ◽  
pp. 2097-2106
Author(s):  
Rai Wung Park
Keyword(s):  
High Performance ◽  
Nonlinear Behavior ◽  
Bilinear System ◽  
Mathematic Model ◽  
Modeling And Control ◽  
Extended Application ◽  
Physical Information ◽  
Complete Form ◽  
And Control ◽  
Operating Points

The transit motion and the rotating motion have highly different effects in a technical systems and have almost nonlinear system behaviors. For the descriptions of their dynamical causes and effects on system, the physical information, which is concerned as a nonlinear mathematic model, has been used. But the corresponding equations are generally not easy to solve in complete form or their solutions are so complicated to see through the coherence. A common way to settle such a problem is to linearize system exactly in a state space or on a operating points with Taylor's series approximately. An advanced method to an approximation is a bilinear system that offers global separations principle. In this paper, an extended application of this theory is given in a modeling and control on the electro hydrostatic cylinder driver with both the transit and rotating motions for the keel system that mostly have not only advantage of high performance, small volume of building and weight but also high nonlinear behavior.

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