scholarly journals Research on the Calculation Method of Harmonic Contribution in the Case of Dominant System-side Harmonics

2021 ◽  
Vol 2095 (1) ◽  
pp. 012006
Author(s):  
Zhaoguang Yang ◽  
Xu Liu ◽  
Jingyu Yang ◽  
Haiping Zhang
Keyword(s):  
Simple Calculation ◽  
Calculation Model ◽  
Measured Data ◽  
Impedance Model ◽  
Practical Engineering ◽  
Regression Error ◽  
Harmonic Voltage ◽  
Engineering Significance ◽  
Partial Linear ◽  
Constant Impedance

Abstract Existing methods for quantifying the responsibility of harmonic sources assume a dominant user side and use a harmonic source equivalence circuit to calculate the equivalent system impedance and background harmonic voltage, which in turn assesses the harmonic contribution of that source to the bus of concern. For users who actively participate in harmonic governance, it is very important to evaluate the responsibility of injecting harmonics into users. This paper assumes system-side is dominant, constructs a partial linear regression model and a constant impedance model, and tracks the regression error. The equivalent fundamental impedance is doubly screened to calculate the harmonic impedance for the corresponding number of times, which in turn quantifies the harmonic voltage duty. The results of simulation and the analysis of measured data show that this method has simple calculation model, small regression error (0.0037), high accuracy and practical engineering significance.

The Research on Unloading Time of Stack Preloading Based on the Measured Data

2013 ◽  
Vol 361-363 ◽  
pp. 1659-1663
Author(s):  
Ji Xin Yang ◽  
Qian Rui Liu ◽  
Zhao Da Zeng
Keyword(s):  
Measured Data ◽  
Class Level ◽  
Practical Engineering ◽  
Unloading Time ◽  
Hyperbolic Method ◽  
Subsidence Curve

Combined with practical engineering, the second-class level measured data is got via stack preloading experiment on the soft and weak railway subgrade. By using the hyperbolic method and three points method to fit subsidence curve, the post-construction settlement S (t =∞) and the settlement at any time S(t) is evaluated, then a reasonable unloading time is inferred by the comparison between S (t =∞) and S(t=180). Studies have shown that hyperbolic method and three points method can predict the post-construction settlement accurately, the time unloading six months after the stack is completed is quite reasonable.

A Fault-Tolerant Offset Algorithm for Measured Data with Defects

2014 ◽  
Vol 902 ◽  
pp. 344-350
Author(s):  
Xiang Jia Li ◽  
Ning Dai ◽  
Wen He Liao ◽  
Yu Chun Sun ◽  
Yong Bo Wang
Keyword(s):  
High Efficiency ◽  
Fault Tolerant ◽  
Engineering Application ◽  
Measured Data ◽  
Sphere Model ◽  
High Quality ◽  
Fitting Method ◽  
Enveloping Surface ◽  
Practical Engineering ◽  
Offset Surface

Offsetting of measured data, as a basic geometric operation, has already been widely used in many areas, like reverse engineering, rapid prototyping and NC machining. However, measured data always carry typical defects like caves and singular points. A fault-tolerant offset method is proposed to create the high quality offset surface of measured data with such defects. Firstly, we generated an expansion sphere model of measured data with the radius equivalent to the offset length. Secondly, using the computational geometry application of convex hull, we acquire the data of outermost enveloping surface of this expansion sphere model. Finally, we use local MLS projection fitting method to wipe out existing defects, and generate the high-quality triangular mesh surface of the offset model. The offset surface generated by this method is suitable for practical engineering application due to its high efficiency and accuracy.

scholarly journals A Harmonic Impedance Identification Method of Traction Network Based on Data Evolution Mechanism

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1904 ◽  
Author(s):  
Ruixuan Yang ◽  
Fulin Zhou ◽  
Kai Zhong
Keyword(s):  
High Reliability ◽  
Measured Data ◽  
Coefficient Of Determination ◽  
Least Squares Regression ◽  
Evolution Mechanism ◽  
Impedance Model ◽  
Identification Method ◽  
Traction Network ◽  
Traction Power Supply ◽  
Data Evolution

In railway electrification systems, the harmonic impedance of the traction network is of great value for avoiding harmonic resonance and electrical matching of impedance parameters between trains and traction networks. Therefore, harmonic impedance identification is beneficial to suppress harmonics and improve the power quality of the traction network. As a result of the coupling characteristics of the traction power supply system, the identification results of harmonic impedance may be inaccurate and controversial. In this context, an identification method based on a data evolution mechanism is proposed. At first, a harmonic impedance model is established and the equivalent circuit of the traction network is established. According to the harmonic impedance model, the proposed method eliminates the outliers of the measured data from trains by the Grubbs criterion and calculates the harmonic impedance by partial least squares regression. Then, the data evolution mechanism based on the sample coefficient of determination is introduced to estimate the reliability of the identification results and to divide results into several reliability levels. Furthermore, in the data evolution mechanism through adding new harmonic data, the low-reliability results can be replaced by the new results with high reliability and, finally, the high-reliability results can cover all frequencies. Moreover, the identification results based on the simulation data show the higher reliability results are more accurate than the lower reliability results. The measured data verify that the the data evolution mechanism can improve accuracy and reliability, and their results prove the feasibility and validation of the proposed method.

Study on Effect of Excavation Depth on Internal Force of Retaining Structure of Arc Row Piles with Arc Ring Beam on the Pile Top

2014 ◽  
Vol 919-921 ◽  
pp. 762-768
Author(s):  
Zhi Wei Zhang ◽  
Rong Gui Deng ◽  
Ze Shuo Chen
Keyword(s):  
Internal Force ◽  
Calculation Model ◽  
Structure Calculation ◽  
Foundation Pit ◽  
Engineering Research ◽  
Retaining Structure ◽  
Body Distribution ◽  
Practical Engineering ◽  
Set Up ◽  
Deformation Compatibility

In order to control deformation of foundation pit effectively and guarantee safety of building around, utilizing the stress characteristics of arch, use the new spatial retaining structure of arc row piles with arc ring beam on the pile top. The arc ring beam can provide constraint to pile top, so internal force of pile body distribution is uniform, and improve the integrity stability of piles. The ring beam with compression mainly can give use of high compression capability of concrete. According to the high order statically indeterminate characteristics of the retaining structure, calculation model of ring beam and pile respectively is established by the redundant forces between beam and pile top. By using deformation compatibility to set up flexibility equation of the retaining structure, and solve the redundant forces, then calculate the internal force and displacement of ring beam and piles. Through calculating the practical engineering, research the effect of excavation depth on internal force and displacement of piles and the arc ring beam on the pile top.

scholarly journals Sensitivity analysis of fire resistance of a composite floor slab

2018 ◽  
Vol 174 ◽  
pp. 01019
Author(s):  
Joanna Kaliszuk ◽  
Elżbieta Grochowska
Keyword(s):  
Sensitivity Analysis ◽  
Fire Resistance ◽  
Simple Calculation ◽  
Calculation Model ◽  
Time Curve ◽  
Composite Slab ◽  
Standard Temperature ◽  
Supporting Structure ◽  
Bending Resistance ◽  
Temperature Time

The paper presents a sensitivity analysis of design bending resistance of a composite slab rib in a fire situation to a change of the value of basic variables. The analysis was carried out for a composite slab being an element of a supporting structure of a reinforced floor referred to in [1, 2]. The calculations were made for a simple calculation model and the standard temperature-time curve according to [6, 7]. The set of basic variables was limited to X1 = {(y, z), h1, fy,a, fy,s, fc}.

Lattice Light Steel Frame System and Application

2011 ◽  
Vol 105-107 ◽  
pp. 1110-1113
Author(s):  
Bo Ding ◽  
Huan Qing Jiang ◽  
Hong Xia Wan ◽  
Feng Zhang
Keyword(s):  
High Speed ◽  
Design Method ◽  
Calculation Model ◽  
Steel Frame ◽  
Calculation Results ◽  
Frame System ◽  
Practical Engineering ◽  
Steel Consumption ◽  
New Type ◽  
New System

Lattice light steel frame is a new type of structural system, combining general steel framework which is composed of lattice column and lattice beam with lattice light steel keel of the partitions and floors, the system takes full advantages of both structural systems, with high speed construction, less steel consumption, good earthquake-resistance etc., and possesses good prospects. The paper describes the system construction approach and the characteristics of lattice light steel frame system, and provides a project example of a villa. The design method and calculation model of the project are presented. Calculation results meet the specifications’ requirements, proving the new system can be applied to practical engineering. The paper gives guidance for application and research of this new system.

MDO of the Transmission System Based Collaborative Optimization

2011 ◽  
Vol 84-85 ◽  
pp. 19-23
Author(s):  
Yun Liu
Keyword(s):  
Fuel Economy ◽  
Optimization Model ◽  
Vehicle Dynamics ◽  
Optimization Methods ◽  
Transmission System ◽  
Collaborative Optimization ◽  
Traditional Design ◽  
Practical Engineering ◽  
Engineering Significance ◽  
Better Than

Collaborative Optimization has been studied a lot in recent years as an algorithm. The Collaborative Optimization is a strategy of a secondary optimization based on the consistency constrained optimization methods. Take ADT’s transmission system as research object, establish collaborative optimization model of the 45 tons ADT transmission system. Set vehicle dynamics and fuel economy as the ultimate optimization goal and then do collaborative optimization. It shows that the results of collaborative optimization methods is better than traditional design. The result is applied to the design of 45 tons ADT transmission system, it has a practical engineering significance.

Application of Ground Penetrating Radar in Tunnel Concrete Lining Quality Detection

2014 ◽  
Vol 1065-1069 ◽  
pp. 358-363
Author(s):  
Meng Meng Zhang ◽  
Xie Dong Zhang
Keyword(s):  
Ground Penetrating Radar ◽  
Concrete Lining ◽  
Construction Process ◽  
Visual Measurement ◽  
Quality Detection ◽  
Media Distribution ◽  
Practical Engineering ◽  
Engineering Significance ◽  
Ground Penetrating ◽  
Frequency Impulse

Ground Penetrating Radar is a method using high frequency impulse electromagnetic wave to detect underground media distribution. It has been gradually widely used as it has the advantage of high accuracy, fast and nondestructive respecting to the conventional method such as visual measurement and confirmation with drilling hole. In the tunnel construction process, it is easy occurred that the quality problem of insufficient lining thickness, the distance of steel arch centering too large and the concrete disengaging. The work achieved in this paper based on the project of LongSheng tunnel and its conclusion and suggestion has important practical engineering significance.

Study on the Aerodynamics Mechanism of Passenger Car under Unsteady Crosswind

2013 ◽  
Vol 631-632 ◽  
pp. 809-816
Author(s):  
Chen Shen ◽  
Hui Zhu ◽  
Zhi Gang Yang
Keyword(s):  
Empirical Formula ◽  
Potential Flow ◽  
Aerodynamic Force ◽  
Vortex Motion ◽  
Flow Theory ◽  
Potential Flow Theory ◽  
Practical Engineering ◽  
Precise Prediction ◽  
Engineering Significance ◽  
Semi Empirical

Regular formulae for lateral aerodynamic force cannot give precise prediction under unsteady crosswind. By generalizing potential flow theory and taking the aerodynamic derivative into consideration, the semi-empirical expression for lateral aerodynamic force is derived. In order to determine the coefficients in the semi-empirical formula, the model of a typical double-deck coach is investigated in a sequence of numerical simulations under pure crosswind condition (i.e. linear crosswind, pseudo-step crosswind, sinusoidal crosswind). Moreover, advantages of the semi-empirical formula over the regular one are revealed. Further inspections into the flow field derived from the theory of vortex motion indicate that the deviation between the prediction given by semi-empirical formulae and that by numerical simulation is caused by the non-viscous assumption in potential flow theory. The lateral aerodynamic force depends linearly on the crosswind aerodynamic derivative. Situations in which the coach is moving in the direction perpendicular to the wind velocity are also studied to find the cause of the error in semi-empirical formula. Furthermore, the semi-empirical formula is revised by introducing the “damping model method”. A relatively complete system of prediction for lateral aerodynamic force on a coach, which is of practical engineering significance, has been constructed.

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