Wahyudin Syam - Wasy Research (Page 2)

Mathematical geometrical fitting: Initial solution problems

Any iterative optimisation algorithms, used to optimise non-linear and multi-modal objective functions, always require an initial solution estimation.

Metrology

Mathematical geometrical fitting: Non-linear geometry least-squared fitting (with tutorial)

The fitting process for non-linear geometry is more complex than that for the linear geometry fitting. Non-linear geometry includes circle (2D and 3D), sphere, cylinder, cone and torus as well as more complex geometries such as free-form surfaces.

Metrology

Mathematical geometrical fitting: Linear geometry least-squared fitting (with tutorial)

The least-squared fitting of linear geometry is solved by transforming a non-linear objective function of residuals into a linear objective function of the residuals.

Metrology

Mathematical geometrical fitting: Concept and fitting methods

One of instrumental aspects in dimensional, geometrical and surface texture measurements is an algorithm to mathematically fit a geometry to spatial points. These spatial points are captured and digitised by a measuring instrument.

Metrology

Optical measuring instrument: Focus variation microscopy (FVM) for coordinate and surface texture measurements

Focus variation microscopy (FVM) is an optical coordinate measuring machine (CMM) that is able to measure both micro-scale part geometry and areal surface texture. An FVM machine can have an up to 5-axis motion system.

Research

Research: Lessons learnt from “Hands of Time: A Watchmaker's History of Time”

Time is the only thing that all humans have equally. Whether they come from a royal family or from an ordinary family, they all have the same 24 hours per day!

GNSS

Post-correlation Carrier to Noise Density (C/N0) calculation in GNSS signal processing

Carrier to Noise Density (C/N0) is one of instrumental metrics for GNSS receiver and signal processing. In this post, C/N0 is calculated at the post-correlation stage (signal tracking) in the GNSS signal processing stage [1].

Research

Research as value and economy creation activities

In this post, we will discuss how to estimate the value (in cash) that can be generated from a research activity. In finance, cash is king!

Applied programming

The problem of writing high-digit numbers into a file and its solution

In this post, the problem of writing a real number with high digit to a file in scientific and numerical computing is presented and discussed.

Tolerancing

Geometric dimensioning and tolerancing (GD&T) and assembly of additive manufacturing parts

In this post, the challenge of applying geometrical dimensioning and tolerancing (GD&T) on additive manufactured (AM) or 3D printed parts will be discussed.

Tolerancing

Geometric dimensioning and tolerancing (GD&T) and assembly of aerospace parts

The assembly feature design and tolerance stack-up analysis of aerospace parts are very important for the analysis of assembly variations or deviations.

Metrology

Uncertainty estimation of laser interferometry measurements

Length or distance measurement with a laser interferometer has an important application in various engineering and scientific fields.

Metrology

Optical measuring instrument: Point auto-focus (PAI) for coordinate and surface texture measurements

Point auto-focus (PAI) optical measuring instrument works based on the principle of following the focus position of a microscope objective lens. This auto-focus mechanism follows the height of the surface of a measured object.

Academic writing

Writing is about “forcing” your idea into others

Writing paper is not about marketing your idea or about conveying your idea to other people. Writing paper is more than that, it is a way to “force” your idea into people so that they use or implement your idea.

Research

Research is a broad ecosystem: All results are important!

Research is a complex ecosystem where all activities and results (in all fields) will be somehow connected, either directly or indirectly, to each other.

GNSS

Evil waveform (EWF) in global navigation satellite system (GNSS) signal

In this post, we will discuss one of GNSS threats, that is evil waveform. Unlike jamming and spoofing, evil waveform is not a type of signal interference in GNSS signals. Instead, evil waveform is a faulty signal transmitted by a real GNSS satellite.

GNSS

The difference between C/N0 and SNR in GNSS signal processing

In signal processing, especially in global navigation satellite system (GNSS), the term signal-to-noise ratio (SNR) and carrier-to-noise density (C/N0) are very fundamental in every analysis aspect.

Tolerancing

Geometric dimensioning and tolerancing (GD&T) and assembly of non-rigid parts

For non-rigid part assembly, the fixturing force will be relevant and needs to be considered carefully in their assembly design.

Metrology

Optical coordinate measuring machine (Optical-CMM): Performance verification and measurement uncertainty estimation

Performance verification and measurement uncertainty estimation of an optical coordinate measuring machine (optical-CMM) are very important aspects assuring that the optical-CMM works within its specification and its measurement results are traceable to the definition of metre.

Metrology

Optical coordinate measuring machine (Optical-CMM): Two fundamental limitations

Optical coordinate measuring machines (Optical-CMM) have advantages over tactile (contact) CMMs, such as more part-feature accessibility, no surface damaging-risk and large surface points capture in relatively a short period of time (compared to tactile CMMs).

Metrology

Digital transformation of dimensional and geometrical measurements

Today era is the time for thorough digitalisation, from product design, process design to data analysis and executive summary making.

Research

Calculus and linear algebra as tools for statistics

Very often, statistics is overlooked by engineers and the importance of statistics is put behind calculus and (linear) algebra.

Applied programming

Prioritising to use built-in functions in interpreted languages

We need to avoid as mush as possible the use of for loop in our algorithm by implementing vectorisation method and using built-in functions as much as possible.

Applied programming

Vectorising linear sequence search in MATLAB programming

To significantly speed up the computation speed in MATLAB, the reduction of for loop should be minimised.

Metrology

CMM measurement uncertainty estimation: ISO 15530-4

The mathematical model of CMM measurements is very complex to reconstruct. ISO 15530-4 presents a method to estimate CMM measurement uncertainty without the need of the mathematical model of CMM measurements.