The project shall contribute to the further development of a prototypical implementation for an assistance solution supporting measurement uncertainty analysis within the existing framework. The main tasks in this project will be:
Familiarisation with the topic of measurement uncertainty analysis and the handling of software GUM Workbench®, definition of an design outline for the user support during measurement uncertainty analysis, including an analysis of required supporting function and the subsequent definition of a possible system structure, selection of one aspect in the process and development of a draft for an adequate support solution, containing elements to enable partial automation or increase of efficiency for the process step as well as explanatory information for the users, prototypical implementation and testing of the defined elements within the outlined framework.
In the "Guide to the Expression of Uncertainty in Measurement" (GUM), jointly issued by ISO and BIPM, a standard procedure for the determination of measurement uncertainty is defined. Yet, although this document is supported by many international organisations and the consideration of measurement uncertainty is of high importance in many fields of application, ranging from industrial quality control to scientific research, still often the determination of measurement uncertainty is omitted.
This is mainly due to difficulties of the metrologists to apply the general rules of the GUM to the task at hand. To ease this task and support the determination of measurement uncertainty, the software GUM Workbench® performs all required mathematical evaluations based on a model of the measurement. Additionally, a concept for an assistance system as well as a graphic modelling editor has been developed to facilitate the definition of a suitable model.
But, the existing concepts are not yet fit for practical testing under industrial conditions.
Table of Contents
1. INTRODUCTION TO UNCERTAINTY MEASUREMENT
1.1 The Definition of Uncertainty Measurement
1.1.1 The Explanation of the Definition
1.1.2 Specification of Measurand
1.1.3 Error, Precision and Uncertainty
1.2 Sources of Uncertainty
1.3 Estimation of Uncertainties
1.3.1 Model the Process
1.3.2 ‘Type A’ Evaluation of Standard Uncertainty
1.3.3 ‘Type B’ Evaluation of Standard Uncertainty
2. GUM WORKBENCH®
2.1 The Software
2.2 Uncertainty Analysis Steps
3. EVALUATION OF THE UNCERTAINTY USING THE GUM WORKBENCH SOFTWARE
3.1 Project 1
Calibration and Measurement Uncertainty of a Power Sensor at a Frequency of 19 GHz Using the Gum Workbench Software
3.1.1 Introduction
3.1.2 The Model Equation and the Input Quantities
3.1.3 Results
3.1.4 Uncertainty budget (Kx)
3.1.5 Discussion
3.2 Project 2
Calibration And Measurement Uncertainty Of Radio Frequency Field Strength Meters Using Broad-Band E Or H-Field Sensor in the Frequency Range up to 18GHz
3.2.1 Introduction
3.2.2 The Evaluation of Uncertainty and Results using GUM
3.2.3 Discussion
4. DEVELOPMENT OF A SUPPORT USER GUIDE DESIGN FOR MEASUREMENT UNCERTAINTY ANALYSIS
4.1 Introduction
4.1.1 The Need of an Assistance System for the Evaluation of the Uncertainty
4.2 General User Guide Procedures
4.2.1 Understanding the Main Experiment
4.2.2 The Measurement Setup
4.2.3 Evaluation of the Uncertainty
4.2.4 Stating Results
4.3 Design Outline for the User Support
4.3.1 Design Outline for First Step
4.3.2 Design Outline for Second Step
4.3.3 Design Outline for Third Step
4.3.4 Design Outline for Fourth Step
4.4 Design Outline for Finding the Model Equation
5. IMPLEMENTATION OF THE USER GUIDE DESIGN AND OTHER SUGGESTED IDEAS
5.1 Introduction
5.1.1 Ways of Implementation and Suggested Ideas
5.2 User Guide Design
Objectives and Research Themes
This Master's thesis aims to support the determination of measurement uncertainty by developing a prototypical user guide and assistance system for the GUM Workbench® software, enabling less experienced users in industrial environments to perform accurate uncertainty analyses.
- Measurement uncertainty analysis according to GUM standards
- Prototypical development of a user-support assistance system
- Case studies: Calibration of Power Sensors and RF Field Strength Meters
- Process optimization and partial automation of uncertainty evaluation
- Integration of user-friendly interface designs into GUM Workbench®
Auszug aus dem Buch
1.2 Sources of Uncertainty
One of the most important parts of finding out the uncertainty is the full understanding of process of the measurement and all sources that lead to uncertainty. This may explain why the skilled engineer or the skilled operator of the measurement experiment is best suited to perform the evaluation procedure. The defining of uncertainty sources starts by testing and analyzing in detail the process of measurement, which mainly includes a complete study of the measurement procedure and the measurement system, using of different of means, including computer simulations and flow diagrams.
There are so many possible sources of uncertainty in testing may include:
- The definition or the understanding of the experiment is incomplete.
For example the requirements are not fully described or understood, as when the temperature is defined as “Room Temperature”.
- Incomplete fulfilment of the definition of the experiment procedure; also when the experiment conditions are clearly defined it may not be possible to produce the required conditions.
- Inappropriate knowledge of the effects of errors in the environmental conditions on the measurement procedure.
- Inadequate measurement of the environmental conditions.
- Sampling; the sample may not be actually representative.
- Parallax errors, personal bias in noticing the analogue measurement tools.
- The resolution of the measurement tool, or the discrimination threshold, or errors in the graduation of the scale.
- Some values referred to standards measurements (both reference and working) and reference materials.
- Modifications in the characteristics or performance of a measurement tool since its last calibration; incidence of drift.
- Some errors in constants values, corrections and other parameters used in data evaluation.
- Assumptions and approximations standardized in the measurement procedure and system.
- Diversities in repeated observations experimented under fairly identical conditions; such random effects may be caused, for example, by short alternations in surrounding environment, for example temperature, humidity and air pressure, or by variability in the performance of the tester.
Summary of Chapters
1. INTRODUCTION TO UNCERTAINTY MEASUREMENT: Defines the fundamental concepts of measurement uncertainty, distinguishes between error and uncertainty, and identifies common sources of uncertainty in experimental procedures.
2. GUM WORKBENCH®: Introduces the GUM Workbench® software as a tool for evaluating measurement uncertainty according to international standards and describes its general analysis workflow.
3. EVALUATION OF THE UNCERTAINTY USING THE GUM WORKBENCH SOFTWARE: Applies the software in two practical case studies: the calibration of a power sensor and the uncertainty analysis of radio frequency field strength meters.
4. DEVELOPMENT OF A SUPPORT USER GUIDE DESIGN FOR MEASUREMENT UNCERTAINTY ANALYSIS: Outlines a structured design for an assistance system aimed at guiding users through the necessary steps of an uncertainty evaluation.
5. IMPLEMENTATION OF THE USER GUIDE DESIGN AND OTHER SUGGESTED IDEAS: Proposes specific technical implementations for the assistance system, such as a tutorial/procedure bar and integrated constants lists, to enhance user efficiency.
Keywords
Measurement Uncertainty, GUM, GUM Workbench, Metrology, Calibration, Power Sensor, RF Field Strength, Assistance System, User Guide, Standard Uncertainty, Type A Evaluation, Type B Evaluation, Measurement Procedure, Industrial Quality Control, Sensitivity Coefficient
Frequently Asked Questions
What is the primary focus of this thesis?
The thesis focuses on facilitating the determination of measurement uncertainty by providing a supportive user guide design for the GUM Workbench® software, specifically for users with varying levels of mathematical and physical background.
What are the central themes discussed in the work?
Key themes include the theoretical definition of measurement uncertainty, the systematic evaluation of uncertainty sources, practical calibration processes, and the development of software-based assistance solutions.
What is the core objective of the proposed assistance system?
The goal is to simplify the complex task of evaluating measurement uncertainty by offering a clear, step-by-step workflow that guides users from the initial measurement task to final documentation and reporting.
Which scientific methods are utilized for the uncertainty evaluation?
The work utilizes standard GUM procedures, including Type A (statistical analysis of repeated observations) and Type B (scientific judgment based on calibration data, handbooks, and specifications) evaluations.
What topics are covered in the main body of the thesis?
The main body covers the fundamentals of uncertainty, the functionality of GUM Workbench®, specific case studies involving power sensors and field strength meters, and the detailed architectural design of the proposed user support system.
Which keywords best describe this research?
Essential keywords include Measurement Uncertainty, GUM, Calibration, RF Field Strength, Assistance System, and User Guide.
How is the calibration factor defined for the power sensor project?
The calibration factor is defined as the ratio of incident power at the reference frequency of 50 MHz to the incident power at the calibration frequency, ensuring both produce the same sensor response.
Why is the "Cause and Effect" diagram recommended in the thesis?
The diagram is recommended as a convenient method to list all potential uncertainty sources and visualize how they relate to one another, preventing the double-counting of influences.
How does the suggested alarm threshold setting improve safety?
By setting the alarm threshold lower than the limiting value by the amount of the expanded uncertainty (e.g., 35V/m instead of 45V/m), the technician ensures a safety probability of over 95% even under unfavorable conditions.
- Quote paper
- Motasem Kharisat (Author), 2015, Assistance for the determination of Measurement Uncertainty Analysis. Development of a prototypical implementation within the existing framework, Munich, GRIN Verlag, https://www.grin.com/document/972503
