scholarly journals Sample Entropy-Based Approach to Evaluate the Stability of Double-Wire Pulsed MIG Welding

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ping Yao ◽  
JiaXiang Xue ◽  
Kang Zhou ◽  
XiaoJun Wang
Keyword(s):  
Standard Deviation ◽  
Pulse Width ◽  
Quantitative Method ◽  
Orthogonal Experiment ◽  
Welding Current ◽  
Sample Entropy ◽  
Mig Welding ◽  
Base Current ◽  
The Stability ◽  
Three Factor

According to the sample entropy, this paper deals with a quantitative method to evaluate the current stability in double-wire pulsed MIG welding. Firstly, the sample entropy of current signals with different stability but the same parameters is calculated. The results show that the more stable the current, the smaller the value and the standard deviation of sample entropy. Secondly, four parameters, which are pulse width, peak current, base current, and frequency, are selected for four-level three-factor orthogonal experiment. The calculation and analysis of desired signals indicate that sample entropy values are affected by welding current parameters. Then, a quantitative method based on sample entropy is proposed. The experiment results show that the method can preferably quantify the welding current stability.

scholarly journals The Systematic Bias of Entropy Calculation in the Multi-Scale Entropy Algorithm

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 659
Author(s):  
Jue Lu ◽  
Ze Wang
Keyword(s):  
Time Series ◽  
Standard Deviation ◽  
Coarse Graining ◽  
Sample Entropy ◽  
Systematic Bias ◽  
Original Time Series ◽  
Multi Scale ◽  
Calculation Results ◽  
Surrogate Measure ◽  
Original Time

Entropy indicates irregularity or randomness of a dynamic system. Over the decades, entropy calculated at different scales of the system through subsampling or coarse graining has been used as a surrogate measure of system complexity. One popular multi-scale entropy analysis is the multi-scale sample entropy (MSE), which calculates entropy through the sample entropy (SampEn) formula at each time scale. SampEn is defined by the “logarithmic likelihood” that a small section (within a window of a length m) of the data “matches” with other sections will still “match” the others if the section window length increases by one. “Match” is defined by a threshold of r times standard deviation of the entire time series. A problem of current MSE algorithm is that SampEn calculations at different scales are based on the same matching threshold defined by the original time series but data standard deviation actually changes with the subsampling scales. Using a fixed threshold will automatically introduce systematic bias to the calculation results. The purpose of this paper is to mathematically present this systematic bias and to provide methods for correcting it. Our work will help the large MSE user community avoiding introducing the bias to their multi-scale SampEn calculation results.

Effect of Current Waveform on Metal Transfer in Controlled Short Circuiting Gas Metal Arc Welding

2013 ◽  
Vol 718-720 ◽  
pp. 202-208 ◽  
Author(s):  
Mao Ai Chen ◽  
Yuan Ning Jiang ◽  
Chuan Song Wu
Keyword(s):  
Transfer Process ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Current ◽  
Metal Transfer ◽  
Arc Voltage ◽  
Metal Arc Welding ◽  
Maximum Stability ◽  
The Stability ◽  
Welding Inverter

With high-speed welding inverter and precisely controlling the welding current with arc-bridge state, advanced pulse current waveforms can be produced to optimize the transfer characteristics of short circuiting transfer welding. In this paper, the images of droplet/wire, and the transient data of welding current and arc voltage were simultaneously recorded to study the influence of peak arcing current, background arcing current and tail-out time on the stability of short circuiting transfer process. It was found that maximum short circuiting transfer stability is reached under specific welding conditions. Any deviation from these conditions will cause abnormal rises in arc voltage indicating instantaneous arc extinguishing and greater spatter. Optimal welding conditions were obtained to achieve the maximum stability of short circuiting metal transfer process.

scholarly journals Study the Effect of Welding Heat Input on the Microstructure, Hardness, and Impact Toughness of AISI 1015 Steel

2018 ◽  
Vol 14 (1) ◽  
pp. 118-127 ◽  
Author(s):  
Emad Kh. Hamd ◽  
Abbas Sh. Alwan ◽  
Ihsan Khalaf Irthiea
Keyword(s):  
Corrosion Rate ◽  
Weld Joint ◽  
Heat Input ◽  
Plate Thickness ◽  
Welding Process ◽  
Welding Current ◽  
Low Carbon ◽  
Mig Welding ◽  
The Impact ◽  
Weld Heat

In the present study, MIG welding is carried out on low carbon steel type (AISI 1015) by using electrode ER308L of 1.5mm diameter with direct current straight polarity (DCSP). The joint geometry is of a single V-butt joint with one pass welding stroke for different plate thicknesses of 6, 8, and 10 mm. In welding experiments, AISI 1015 plates with dimensions of 200×100mm and edge angle of 60o from both sides are utilized. In this work, three main parameters related to MIG welding process are investigated, which are welding current, welding speed, heat input and plate thickness, and to achieve that three groups of plates are employed each one consists of three plates. The results indicate that increasing the weld heat input (through changing the current and voltage) leads to an increase in widmanstatten ferrite (WF), acicular ferrite (AF) and polygonal ferrite (PF) in FZ region, and a reduction in grain size. It is observed that the micro-hardness of welded AISI 1015 plate increases as the weld heat input decreases. As well as increasing the weld heat input results in an increase in the width of WM and HAZ and a reduction in the impact energy of the weld joint of AISI 1015 at WM region. Also, it is noted the corrosion rate of weld joint increases with increase of Icorr due to increasing in welding current (heat input), corrosion rate increased up to (0.126µm/yr.) with increasing of heat input up to (1.27 KJ/mm).  

Effect of test parameters on the stability of fabric shape retention indexes increase recovery testing

2021 ◽  
pp. 004051752110242
Author(s):  
Qianhui Tang ◽  
Lei Wang ◽  
Weidong Gao ◽  
Ruru Pan
Keyword(s):  
Standard Deviation ◽  
Sample Size ◽  
Orthogonal Test ◽  
Test Scheme ◽  
Optimal Test ◽  
Pressure Time ◽  
Test Parameters ◽  
Shape Retention ◽  
The Stability ◽  
Retention Indexes

Fabric shape retention is a crucial property that impacts the durability and usability of fabric and which needs a convenient and accurate evaluation method. In the previous research, the automated crease recovery testing method was used to obtain fabric crease recovery information and evaluate the property of shape retention. Based on the previous research, an orthogonal test method was adopted to investigate the effect of different test parameters on the stability of shape retention detection in this paper. First, three factors, that of sample size, pressure, and pressure time, and three different levels of each factor were determined by the L9(34) orthogonal test table. Next, the fabric shape retention indexes were detected by nine different test schemes, and the comprehensive score of shape retention index standard deviation was obtained as the evaluation criterion of the orthogonal test results. Finally, the optimal test scheme was determined by visual analysis and variance analysis. The results show that the sample size has a certain effect on the stability of shape retention indexes, while the pressure time and the pressure have no significant influence. The optimal test scheme is that the sample size is 30 cm × 30 cm, the pressure time is 60 s, and the pressure is 40 N. The test result measured by the optimal test parameters reveals excellent stability when the vertex angle standard deviation is 2.0°, the height standard deviation is 0.06 cm, and the shape retention area standard deviation is 0.16 cm2. This paper provides an experimental basis for improving the accuracy of fabric shape retention evaluation method.

Study of Dynamic Modes of Current Stabilization Systems of Powerful Electromagnets with Pulse-Width Modulation

2021 ◽  
Vol 22 (6) ◽  
pp. 313-320
Author(s):  
M. S. Lur’e ◽  
O. M. Lur’e ◽  
A. S. Frolov
Keyword(s):  
Pulse Width ◽  
Pulse Width Modulation ◽  
Functional Differential Equations ◽  
Original System ◽  
Nyquist Stability ◽  
Detailed Assessment ◽  
Functional Differential ◽  
The Stability ◽  
Automatic Systems ◽  
A Current

This study is devoted to the consideration of a method for assessing the stability of systems with pulse-width modulation, based on the linearization of its equivalent system with pulse-width modulation. An approximate study of the dynamic modes of operation of systems with pulse-width modulation, taking into account the stability for the system of automatic control of the supply current of electromagnets under the conditions of external and internal interference, is carried out. Variants of execution of schemes of pulse-width regulators for the power supply of an electromagnet based on a unipolar and bipolar element with pulse-width modulation are presented. The possibility of linearization of systems with pulse-width modulation for the subsequent detailed assessment of the stability of such systems is shown. The prospects of using functional differential equations for stability analysis of automatic systems with pulse-width modulation are shown. The frequency characteristics of an equivalent pulse system are analyzed using the example of a current stabilization system of high-power electromagnets with a pulse-width regulator, taking into account the replacement of the latitude modulation by the amplitude one. Based on the analysis of the resulting transfer function, which is a stable linearized equivalent open system, the ways of evaluating the stability of the original system with pulse-width modulation using the Nyquist stability criterion are proposed. The conclusion is made about the advantage of a system with PWM, in relation to a system with AIM, in terms of stability, and recommendations are given for the use of the obtained data in the analysis oftransients in such systems.

Automated Method for the Analysis of Riboflavin in Milk, with Application to Other Selected Foods

1974 ◽  
Vol 57 (5) ◽  
pp. 1085-1088
Author(s):  
James R Kirk
Keyword(s):  
Standard Deviation ◽  
Continuous Flow ◽  
Quantitative Method ◽  
Green Fluorescence ◽  
Internal Standards ◽  
Automated Method ◽  
Sodium Hydrosulfite ◽  
Automated Technique ◽  
Good Agreement

Abstract A continuous flow automated technique was developed for the determination of riboflavin in milk. The determination is based on the measurement of the natural yellow-green fluorescence of riboflavin at an excitation of 436 nm and emission of 510 nm. Blank values are determined for each sample after sodium hydrosulfite reduction of the riboflavin. Mean recovery and standard deviation for riboflavin in milk determined by the continuous flow procedure using internal standards were 9 7% and ± 2.42%, respectively. The recovery value was in good agreement with that determined using a manual procedure, while the standard deviation was 33% less than that found when using the manual procedure. The results from this study indicate that the continuous flow automated procedure for the determination of riboflavin in milk is a simple, quantitative method which eliminates many of the time-consuming analytical steps.

scholarly journals Influence of Current Feeding Position of Duplex Current Feeding MIG Welding on Droplet Heat Quantity

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3590
Author(s):  
Atsuhito Aoki ◽  
Shinichi Tashiro ◽  
Hideaki Kurokawa ◽  
Manabu Tanaka
Keyword(s):  
Welding Process ◽  
Welding Current ◽  
Mig Welding ◽  
Secondary Current ◽  
Pure Argon ◽  
Large Current ◽  
Heat Quantity ◽  
Feeding Speed ◽  
Wire Feeding ◽  
Simplified Calculation

Pure argon metal inert gas (MIG) welding is expected to offer the possibility to obtain high toughness weld joints. However, due to its arc instability and low wettability, it is difficult to apply pure argon MIG to a practical welding structure. In order to solve these problems, an improved MIG welding process with a duplex current feeding (DCF-MIG) mechanism was developed. In the DCF-MIG process, the welding current and the wire feeding speed are independently controlled by an additionally feeding secondary current from a secondary power source. Thereby, DCF-MIG can supply a large current compared to conventional MIG under the same deposition rate. In this study, to consider the influence of the secondary current feeding position of DCF-MIG on droplet heat quantity, droplet heat quantity was measured by calorimetry. As a result, the droplet heat quantity was found to be increased significantly with the increase of the distance between the primary current feeding point and secondary current feeding point. The increase of the droplet heat quantity in the DCF-MIG process had a strong effect on improving bead shape and penetration. The droplet heat quantity with the effective current value of DCF-MIG was derived from the simplified calculation and the results roughly agreed with the experimental data.

Acoustic Information Acquisition and Time Domain Analysis on Alternating Current Rail Flash Butt Welding

2012 ◽  
Vol 239-240 ◽  
pp. 16-20
Author(s):  
Qi Bing Lv ◽  
Ke Li Tan ◽  
Xi Zhang ◽  
Jian Chen ◽  
Guo Qing Liu
Keyword(s):  
Time Domain ◽  
Acoustic Signal ◽  
Information Acquisition ◽  
Welding Process ◽  
Welding Current ◽  
Time Domain Analysis ◽  
Mean Square ◽  
Butt Welding ◽  
The Mean ◽  
The Stability

Based on the mobile rail flash butt welding machine UN5-150ZB, the synchronous data acquisition hardware system was designed to collect welding current, welding voltage and flash acoustic signal in welding process, and the software platform with the functions of signal collecting, waveform display and data operation was developed by higher-level programming language LabVIEW. After the welding current, welding voltage and flash acoustic signal in welding process had been collected, the mean, variance and mean square value of flash acoustic signal in time-domain were analyzed. Through comparison, the relationship between these characteristics and the stability of flash was analyzed. The result shows that the changes of mean and variance of flash acoustic signal are not obvious, and do not correlate with stability of flash, but the mean square value in time domain is closely associated with the stability of flash, and the stability of flash can be indicated by the mean square value.

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