Application of the “Worst Case” Method to Estimate the Spectrum and Power Measurement Error Caused by ADC Imperfection

2021 ◽  
Author(s):  
Andrey N. Serov
Keyword(s):  
Measurement Error ◽  
Power Measurement ◽  
Case Method ◽  
Worst Case

Harmonic Impact on the Energy Meter

2013 ◽  
Vol 645 ◽  
pp. 263-266
Author(s):  
Bing Han ◽  
Hao Feng ◽  
Yuan Yuan Liu ◽  
Feng Han
Keyword(s):  
Measurement Error ◽  
Power System ◽  
Harmonic Generation ◽  
Power Measurement ◽  
Measuring Instrument ◽  
Nonlinear Loads ◽  
Energy Meter

A large number of harmonics generated by nonlinear loads injected into the grid will make the power system voltage and current waveforms produce a serious distortion, in turn impact on the measuring instrument. Harmonic generation because and it’s impact on induction watt-hour meter are introduced in this paper, the measurement error on the induction meter is analized, and methods and countermeasures to reduce the induction meter power measurement error are proposed.

Process Capability Based Tolerance Allocation in Pneumatic Percussive Riveting

2020 ◽  
Author(s):  
Hua Wang ◽  
Jialei Zhang ◽  
Junyang Yu
Keyword(s):  
High Efficiency ◽  
Load Transfer ◽  
Process Capability ◽  
Tolerance Analysis ◽  
Tolerance Allocation ◽  
Hole Drilling ◽  
Case Method ◽  
Pneumatic Hammer ◽  
Worst Case ◽  
Mating Conditions

Abstract Pneumatic percussive riveting is an important way to join the sheet metals. In order to ensure the load transfer and the fatigue performance of riveted joint, the interference of the rivet/hole is strictly specified. The interference of the rivet/hole is highly correlated with the process capability of the pneumatic hammer and the diameter of the pre-hole. It is a critical step to choose the appropriate pneumatic hammer to ensure the interference requirements. Energy per blow of the pneumatic hammer is a proclaimed parameter from the riveting hammer manufacturer. It is difficult for the designer to choose the riveting hammer in practical riveting scheme based on energy per blow. Tolerance analysis is an efficient way to model the manufacturing variation and implement process control. This paper presents the tolerance allocation of the pneumatic percussive riveting based on the process capability of the pneumatic hammer. In order to obtain the designed interferences of the rivet/hole, a tolerance chain is built with the process capability of the pneumatic hammer, the diameter of the pre-hole and the diameter of the rivet shank. The process capability of the pneumatic hammer is represented with the interferences of the rivet/hole after riveting. It is an intuitive parameter for the designer to choose the riveting hammer in practical riveting scheme. The process capability of the pneumatic hammer is obtained from the designed riveting experiments with the pneumatic percussive riveting platform. The diameter of the pre-hole affects the interference of the rivet/hole also. The tolerance for manual hole-drilling should be determined to assure the interference requirements and high drilling operation efficiency simultaneously. The variation of the pre-hole is obtained from the manual drilling experiments and diameter measurements. Different hole-drilling results in different mating conditions between the pre-hole and the rivet. The fit conditions of different pre-holes are modeled and the final interferences after riveting are analyzed. Worst case method and statistical analysis method are two common methods for tolerance analysis. For the manual hole-drilling and the pneumatic percussive riveting, worst case method is employed to analyze the constructed tolerance chain in order to accomplish the interferences of the rivet/hole. The different analyzed dimensions, rivet-hole clearances and pre-hole drilling variation, are investigated respectively. The reported work enhances the understanding of the tolerance allocation for the pneumatic percussive riveting. The interference based process capability of the pneumatic hammer provides good reference for pneumatic hammer choosing in riveting scheme. The reported tolerance chain of the interference could be used for the tolerance determination of manual hole-drilling with good quality and high efficiency.

scholarly journals Tolerance Analysis of Mechanical Parts

2020 ◽  
Vol 14 (3) ◽  
pp. 265-272
Author(s):  
Živko Kondić ◽  
Đuro Tunjić ◽  
Leon Maglić ◽  
Amalija Horvatić Novak
Keyword(s):  
Tolerance Analysis ◽  
Case Method ◽  
Worst Case ◽  
Mechanical Parts ◽  
Assembly Tolerance ◽  
Huge Impact ◽  
Quality Of Products ◽  
The One

The determination of tolerances has a huge impact on the price and quality of products. The objective of tolerance analysis is to provide the widest possible tolerance range of parts, without disturbing the functionality of the assembly. Tolerance analysis should be performed during the design process because then there is still the possibility for change. For the purpose of carrying out the analysis, three methods will be used: Worst Case method, Root Sum Square method and Monte Carlo Simulation. Methods are explained through simple examples and applied on the one-way clutch.

Uncertainty analysis by the "worst case" method

1984 ◽  
Vol 61 (9) ◽  
pp. 780 ◽  
Author(s):  
Roy Gordon ◽  
Miles Pickering ◽  
Denise Bisson
Keyword(s):  
Uncertainty Analysis ◽  
Case Method ◽  
Worst Case

scholarly journals Robustness assessment of a novel 4D optimization approach for lung cancer radiotherapy

2021 ◽  
Author(s):  
Shahad M. Al-Ward
Keyword(s):  
Lung Cancer ◽  
Image Data ◽  
Maximum Intensity ◽  
Planning Method ◽  
Case Method ◽  
Worst Case ◽  
Case Methods ◽  
Patient Motion ◽  
Wide Range ◽  
Case Planning

One of the main challenges to treatment of lung cancer with radiation therapy is the tumor motion due to respiration. Previously, a novel approach was developed to generate treatment plans which compensate for respiratory motion and its variations. The worst case method is based on combining two intensity maps from two 4D plans optimized on the two worst cases of motion variations. The worst case planning method was previously tested on simulated motion variations. The goal of this project was to further test the worst case approach on realistic patient motion variations and treatment planning data. Two approaches to combining worst case plans were investigated: the first method takes the average of the two intensity maps, and the second method takes the maximum intensity of the two intensity maps. The robustness of worst case plans was compared with ITV plans and nominal 4D plans on three different motion variation scenarios. Study 1 and 2 investigated the robustness of the worst case methods on amplitude variations and patient motion variations on simulated image data. Study 3 investigated the robustness of the worst case methods on patient motion variations using real patient image data. The average intensity worst case method was only robust to Study 3 motion variations. The maximum intensity worst case method, the margin based, and the nominal approaches were not robust to any of the motion variations. Further evaluation over a wide range of tumour sizes, motion amplitudes and variability is required to determine the clinical applicability of the worst case planning method.

scholarly journals Robustness assessment of a novel 4D optimization approach for lung cancer radiotherapy

2021 ◽  
Author(s):  
Shahad M. Al-Ward
Keyword(s):  
Lung Cancer ◽  
Image Data ◽  
Maximum Intensity ◽  
Planning Method ◽  
Case Method ◽  
Worst Case ◽  
Case Methods ◽  
Patient Motion ◽  
Wide Range ◽  
Case Planning

One of the main challenges to treatment of lung cancer with radiation therapy is the tumor motion due to respiration. Previously, a novel approach was developed to generate treatment plans which compensate for respiratory motion and its variations. The worst case method is based on combining two intensity maps from two 4D plans optimized on the two worst cases of motion variations. The worst case planning method was previously tested on simulated motion variations. The goal of this project was to further test the worst case approach on realistic patient motion variations and treatment planning data. Two approaches to combining worst case plans were investigated: the first method takes the average of the two intensity maps, and the second method takes the maximum intensity of the two intensity maps. The robustness of worst case plans was compared with ITV plans and nominal 4D plans on three different motion variation scenarios. Study 1 and 2 investigated the robustness of the worst case methods on amplitude variations and patient motion variations on simulated image data. Study 3 investigated the robustness of the worst case methods on patient motion variations using real patient image data. The average intensity worst case method was only robust to Study 3 motion variations. The maximum intensity worst case method, the margin based, and the nominal approaches were not robust to any of the motion variations. Further evaluation over a wide range of tumour sizes, motion amplitudes and variability is required to determine the clinical applicability of the worst case planning method.

scholarly journals Investigation of the fake reject cases with unqualified operational dimension based on the error compensation and tolerance compression

2021 ◽  
Author(s):  
Xiaosan Ma ◽  
Feng Jiao ◽  
Wenhui Feng ◽  
Wenbo Bie ◽  
Fan Chen
Keyword(s):  
Error Compensation ◽  
Case Method ◽  
Remedial Measures ◽  
Remedial Measure ◽  
Worst Case ◽  
Qualification Rate ◽  
Process Dimension ◽  
Operational Data ◽  
Compensation Relationship ◽  
Operational Dimension

A fake reject (FR) with unqualified operational dimension often occurs during part machining when the operational data do not coincide with the design ones. This may lead to unnecessary waste. A novel judgment and remedial measures for FR are investigated in this paper to enhance products' qualification rate. Firstly, the reasons for the FR occurrence are discussed based on the fact that the operational dimension tolerance calculated using the worst-case method of the process dimension chain calculation is too tight. Secondly, a novel judgment method of FR is proposed by calculating a new dimension chain. The operational dimension is treated as the concluding link. The actual deviations of the dimensions generated before the operational dimension generation are used to replace their upper and lower deviations. Finally, based on the error compensation relationship among the component links in the process dimension chain, a novel remedial measure of FR by compressing dimension tolerance in subsequent processing is proposed. The calculation flow of the dimension tolerance after tolerance compression is worked out. This study's results of this study are considered for instrumental in judging and processing FR in part machining.

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