scholarly journals Measurement of reflection coefficient for a double-layered scaled model using the inverse filter

2021 ◽  
Vol 336 ◽  
pp. 01018
Author(s):  
Hao Song ◽  
Xiaowei Yan ◽  
Xiaochen Ma ◽  
Zixian Cui ◽  
Qi Li
Keyword(s):  
Reflection Coefficient ◽  
Pulse Signal ◽  
Least Square Method ◽  
Least Square ◽  
Experimental Results ◽  
Inverse Filtering ◽  
Inverse Filter ◽  
Scaled Model ◽  
Low Frequencies ◽  
The Cost

A method of measuring the reflection coefficient for a double-layered scaled model using the inverse filter is presented. First, the response of the circuit and underwater acoustical channel is measured, and the retransmitted inverse signal isestimated with the least square method for solving the cost function, which is constructed by the inverse filtering theory. Then, by retransmitting the inverse signal, the incident signal at the position of the double-layered scaled model is focused with high-main-lobe resolution, low side-lobelevel and a narrow pulse signal in temporal domain. The focus improves the measurement accuracy of the reflection coefficient for the double-layered scaled model in low frequencies. The feasibility of replacing the whole cylindrical with the double-layered scaled model is verified by simulation. The validity of the proposed method is verified by experiments carried out in a cylindrical tank for a double-layered scaled model at the frequency 0.5 kHz~10 kHz. The experimental results show that the proposed method is effective to the measurement of the reflection coefficient for the double-layered scaled model.The experimental results for the double-layered scaled model with acoustical coating on different shells have strongly directive significance for the process design and improvement of the acoustical coating.

Determination of Johnson Cook Material Model Constants and Their Influence on Machining Simulations of Tungsten Heavy Alloy

2018 ◽  
Author(s):  
Chithajalu Kiran Sagar ◽  
Amrita Priyadarshini ◽  
Amit Kumar Gupta ◽  
Sidharth Kumar Shukla
Keyword(s):  
Least Square Method ◽  
Material Model ◽  
Least Square ◽  
Experimental Results ◽  
Tungsten Heavy Alloy ◽  
Fe Model ◽  
Abc Algorithm ◽  
Bee Colony ◽  
Aircraft Manufacturing ◽  
Heavy Alloys

Tungsten Heavy Alloys (WHA) are used in counterbalance and ballast weights for aerodynamic balancing in fixed and rotary wing aircraft. Manufacturing these components for closer tolerances using machining is a challenging task. The present work aims to develop a 2D Finite Element (FE) model to simulate the chip formation process during machining of WHA using Johnson Cook Material Model (JCMM). The model constants for 95%WHA are determined based on the high strain rate test data using least square method. The calculated values are further optimized using Genetic Algorithm (GA) and Artificial Bee Colony (ABC) algorithm, which are then used as material inputs for FE simulation of machining WHA. The predicted results such as cutting force, chip geometry, shear stress, shear angle are presented and compared with the experimental results under similar cutting conditions. It has been observed that the constants obtained from ABC algorithm show minimum error in the cutting performance measures for all the experimental results.

Localization of Mobile Robot Based on Least Square Method

2013 ◽  
Vol 347-350 ◽  
pp. 808-811
Author(s):  
Jia Lu Li ◽  
Lin Bing Long ◽  
Bao Feng Zhang
Keyword(s):  
Motion Estimation ◽  
Mobile Robot ◽  
Mobile Robots ◽  
Least Squares ◽  
Least Square Method ◽  
Least Square ◽  
Experimental Results ◽  
Sift Algorithm ◽  
Key Techniques ◽  
Point Detection

Localization is the basis for navigation of mobile robots. This paper focuses on key techniques of localization for mobile robots based on vision. Firstly, the specific measures and steps of the algorithm are analyzed and researched in depth. In the study, SIFT algorithm combined with epipolar geometry constraint is used on the environment feature point detection, matching and tracking. And the method of RANSAC combined with the least squares is used to obtain accurate results of the motion estimation. Then the necessary experiments are carried out to verify the correctness and effectiveness of algorithms. The experimental results verified the accuracy of the improved algorithm.

Comparing of Coordinate Transformation Based on Total Least Squares and Least Squares

2014 ◽  
Vol 522-524 ◽  
pp. 1211-1214
Author(s):  
Qing Wu Meng ◽  
Lu Meng
Keyword(s):  
Least Squares ◽  
Coordinate Transformation ◽  
Least Square Method ◽  
Coefficient Matrix ◽  
Total Least Squares ◽  
Least Square ◽  
Experimental Results ◽  
Transformation Models ◽  
Total Least Square

The coordinate transformation models based on least square method and total least square are built and discussed. The least square model only includes the errors of observation vectors, the total least square model simultaneously takes into consideration to the errors of observation vectors and the errors of coefficient matrix. The both models are verified and compared in experiment. The experimental results showed that the model of total least square is more in line with actual, and more reasonable than by least square theoretically, and the coordinate transformation solution result of total least square with least square is more near.

Signal Conditioning of Low-Cost Gyroscope Using Kalman Filter and Nonlinear Least Square Method

2012 ◽  
Vol 622-623 ◽  
pp. 1519-1523
Author(s):  
C. Saraporn ◽  
T. Dolwichai ◽  
J. Srisertpol ◽  
K. Teeka
Keyword(s):  
Kalman Filter ◽  
Motion Control ◽  
Low Cost ◽  
Least Square Method ◽  
Scaling Factor ◽  
Least Square ◽  
Experimental Results ◽  
Signal Conditioning

Gyroscopes are important sensors in motion control in equipment such as airplanes, missiles and Segway. Low-cost gyroscopes have problems in signals such as bias, noise and scaling factor that decrease the efficiency of motion control. Therefore this paper is to present signal conditioning of low-cost gyroscopes using a Kalman filter to remove unwanted noise and nonlinear least square method to estimate parameters for compensation errors to the model by comparison with the encoder. The experimental results is shown that Kalman filter and nonlinear least square method can be used in signal conditioning of low-cost gyroscope for a more accurate signal.

An Algorithm and Design for RFID Velocity Measurement Based on Least Square Method

2011 ◽  
Vol 317-319 ◽  
pp. 1573-1576
Author(s):  
Lin Ying Jiang ◽  
Heng Zhang ◽  
Han Qing Tan
Keyword(s):  
Great Degree ◽  
Velocity Measurement ◽  
Least Square Method ◽  
Least Square ◽  
Measuring System ◽  
Rfid Technology ◽  
Velocity Measuring ◽  
The Cost

This paper comes up with an algorithm and application for velocity measurement based on RFID technology. This measurement can reduce the cost of velocity-measuring system to a great degree, and improve the accuracy of velocity measurement on the basis of the algorithm.

Combined Phase Unwrapping Method Using 2D Image Information in PMP 3D Measurement

2013 ◽  
Vol 765-767 ◽  
pp. 2148-2152 ◽  
Author(s):  
Yue Hua Gao ◽  
Bing Luo ◽  
Zhong Yu Sun ◽  
Su Fang Zhao
Keyword(s):  
Basic Principle ◽  
Least Square Method ◽  
Phase Unwrapping ◽  
Least Square ◽  
Experimental Results ◽  
Solder Paste ◽  
3D Measurement ◽  
Image Information ◽  
Practical Engineering ◽  
Break Area

In SMT solder paste deposit 3D measurement based on PMP, conventional phase unwrapping method suffered from shadow, noise and holes. Considering practical engineering condition, phase unwrapping method can be improved using 2D image information: basic principle method was applied to smooth area, quality-guided unwrapping and least-square method were taken in shadow or break area for phase unwrapping respectively. Experimental results show that desired phases can be correctly and quickly unwrapped in proposed method.

Calculating the Overcut in Electro-Discharge Machining

2005 ◽  
Vol 291-292 ◽  
pp. 561-566
Author(s):  
Fu Ling Zhao ◽  
H. Wang ◽  
Z.Z. Lu
Keyword(s):  
Empirical Formula ◽  
Reasonable Agreement ◽  
Dimensional Accuracy ◽  
Least Square Method ◽  
Least Square ◽  
Experimental Results ◽  
Electrode Wear ◽  
Current Pulse Duration ◽  
Electro Discharge Machining ◽  
Discharge Gap

The dimensional accuracy of electro-discharge machining (EDM) is greatly influenced by the overcut resulting from discharge gap and electrode wear. In order to achieve fine accuracy, it is necessary to estimate the overcut according to an empirical formula. In this paper, experiments in electro-discharge machining were carried out. The effects of parameters on the overcut, such as peak current, pulse duration, were analyzed. Then an empirical formula for the overcut in EDM was established based on the experimental results using the least square method. Finally, reasonable agreement between calculated results and the further experimental results was obtained.

A Study on Velocity Decay of φ6mm Tungsten Ball Fragment

2014 ◽  
Vol 1042 ◽  
pp. 154-158
Author(s):  
Chun Lin Yi ◽  
De Ren Kong ◽  
Yi Zhao Li ◽  
Li Ping Li ◽  
Jin Qiu Zhang ◽  
...  
Keyword(s):  
High Speed ◽  
Least Square Method ◽  
Least Square ◽  
Experimental Results ◽  
Measuring System ◽  
Low Speed ◽  
Velocity Decay ◽  
Velocity Attenuation ◽  
Attenuation Models ◽  
Velocity Measuring

In order to explore the velocity attenuation law and model of φ6mm tungsten ball fragment, theory analysis combined with tests is employed to study its velocity experimental results. First of all, a fragment velocity measuring system including 12 groups of cutting device is established. Then the attenuation experiments of φ6mm tungsten ball fragment in high speed and low speed velocity are performed by the measuring system. Based on the least-square method, MATLAB software is adopted to analysis the experimental data and obtained the high speed and low speed velocity attenuation models. The results show that φ6mm tungsten ball fragment speed attenuation coefficient is consistent in high speed and low. Thus, the analysis on velocity experimental results verifies that the established model is reasonable.

Malaria and Pneumonia Effects on Rice, Vanilla Production and Rural Household Income In Madagascar: A Quantitative Study

2021 ◽  
Author(s):  
Marilys Victoire Razakamanana ◽  
Martine Audibert ◽  
Voahirana Tantely Andrianatoandro
Keyword(s):  
Least Squares ◽  
Quantitative Study ◽  
Household Income ◽  
Least Square Method ◽  
Rural Household ◽  
Least Square ◽  
Two Stage ◽  
Ordinary Least Square ◽  
Under Five ◽  
The Cost

Abstract Background: In Madagascar, malaria remains the leading cause of consultation and deaths at hospital at all ages and pneumonia is one of the main causes of the under-five mortality and account for 45% of children hospitalizations. The number of cases and deaths has not decreased during the last ten years. This paper aims to determine the effects of malaria and pneumonia on rice and vanilla production and income.Methods: We use data from survey lead by the authors on 975 households and 3,586 individuals of the SAVA region in the northeast of Madagascar. After checking the presence of endogeneity, ordinary least-square method was used instead of two-stage least squares.Results: Our results showed that malaria has no effect on production, and therefore does not affect income. Pneumonia has an effect on production of rice and vanilla. Moreover, the cost of malaria and pneumonia healthcare burdened by households affect their consumption. Conclusions: Therefore, pneumonia should be considered in the same way as malaria due to its effects on production and investment to fight against these two diseases must be strengthened in order to decrease the costs for the households.

Study on AC Artificially Pollution Flashover Performance of Long Porcelain Insulator String

2015 ◽  
Vol 713-715 ◽  
pp. 975-978 ◽  
Author(s):  
Yan Shi ◽  
Gang Hu ◽  
Yong Chen
Keyword(s):  
Power Function ◽  
Least Square Method ◽  
Least Square ◽  
Experimental Results ◽  
Porcelain Insulator ◽  
Pollution Flashover ◽  
Flashover Voltage ◽  
The One ◽  
The Relationship ◽  
Mutually Independent

In this paper,the relationship between 50% ac flashover voltage (U50) of long porcelain insulator string and ρESDD and ρNSDD was analyzed based on experimental results. It was shown that the relationship between U50 and ρESDD is the same as the one between U50 and ρNSDD, in which the U50 reduces with the increase of ρESDD by a power function, and the influences of ρESDD and ρNSDD on U50 are mutually independent. By using the least square method, the value of exponent of a and b were determined.

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