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Data Acquisition and Analysis. HU164_Lecture 5. RESEARCH METHODS:. Experimental research Descriptive Relational Difference. All Require Data. Distance Measuring Methods/devices. Pacing Odometer Chaining Stadia Electronic Distance Measuring (EDM) Global Positioning System (GPS).
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Data Acquisition and Analysis HU164_Lecture 5
RESEARCH METHODS: • Experimental research • Descriptive • Relational • Difference All Require Data HU164_Lec4_Data Acquistion
Distance Measuring Methods/devices • Pacing • Odometer • Chaining • Stadia • Electronic Distance Measuring (EDM) • Global Positioning System (GPS) HU164_Lec4_Data Acquistion
The “Best” Method The best distance measuring method/device to use is influenced by many factors. • Environment • Use of the data • Equipment available • Expertise of individuals • Personal preference • Topography • Client specifications • Regulations • Standard practice The most important factor is the intended use of the data. HU164_Lec4_Data Acquistion
Output, Vo (V) Force, F Slope = 5 V/kN Output, Vo Load Cell Input, Fi (kN) Block Diagram: Input, F (kN) Output, Vo (V) K Sensitivity, K = 5 V/kN HU164_Lec4_Data Acquistion
Resolution This is defined as the smallest input increment change that gives some small but definite numerical change in the output. HU164_Lec4_Data Acquistion
Data Acquisition System • A data acquisition system consists of many components that are integrated to: • Sensephysical variables (use of transducers) • Condition the electrical signal to make it readable by an A/D board Analogue-to-Digital converter HU164_Lec4_Data Acquistion
DAS Functions • Convert the signal into a digital format acceptable by a computer • Process, • Analyze, • Store, and • Display the acquired data with the help of software HU164_Lec4_Data Acquistion
Typical Block Diagram for DAS HU164_Lec4_Data Acquistion
Examples Temperature Pressure Light Force Displacement Level Electric signals Transducers Sense physical phenomena and translate it into electric signals. HU164_Lec4_Data Acquistion
Signal Conditioning Electrical signals are conditioned so they can be used by an analog input board. The following features may be available: • Amplification - Isolation • Filtering - Linearization HU164_Lec4_Data Acquistion
4 Samples/cycle 16 Samples/cycle Analog Input 8 Samples/cycle Analog to Digital (A/D) Converter • Input signal • Sampling rate HU164_Lec4_Data Acquistion
A/D Converter: Resolution HU164_Lec4_Data Acquistion
Data Acquisition Software • It can be the most critical factor in obtaining reliable, high performance operation. • Transforms the PC and DAQ hardware into a complete DAQ, analysis, and display system. • Different alternatives: • Programmable software. • Data acquisition software packages. HU164_Lec4_Data Acquistion
Designing a DAS: Factors to Consider • Fixed or a mobile application • Type of input/output signal: digital or analog • Frequency of input signal • Resolution, range, and gain • Continuous operation • Compatibility between hardware and software. Are the drivers available • Overall price. HU164_Lec4_Data Acquistion
References • Measurement and Data Analysis for Engineering and Science (2nd Edition) by Patrick F. Dunn, CRC Press, 2010 • A Practical Guide to Scientific Data Analysis, David J. Livingstone, Wiley, 2009 HU164_Lec4_Data Acquistion
All analysis involves theory • Because your prior ideas guides your eyes • Because “pure observations”, neutral and objective, not guided by your “prejustice”, is unlikely HU164_Lec4_Data Acquistion
Quantitative inquiry • Theory guides the development of instruments • If not: theory is still embedded in the instrument • An analysis of the instruments might reveal the underlying theory • Knowledge of the instrument’s theory-base is necessary to interpret findings in adequate terms HU164_Lec4_Data Acquistion
Data Analysis HU164_Lec4_Data Acquistion
Qualitative inquiry • Theory guides • the foci for the study • the research questions • the collection of data • the analysis of data HU164_Lec4_Data Acquistion
Quiz 1 12/11/2012 Answer one question only • State three steps to critically evaluate information and discuss one of them. • Differentiate between hypothesis, assumption and theory, providing example for each. HU164_Lec4_Data Acquistion