Software development

A revised open source usability defect classification taxonomy

Each is subjective based on the experience of those who created the taxonomies. If they are used in similar circumstances, an additional benefit to having a taxonomy is that later on, test cases can be built on them. Simply put, a tester with taxonomy at his disposal has higher chances of success.

definition of defect taxonomy

The crack in turn can result in material lift-up or breaking away of a significant piece of the blade. No application of blade defects is apparent in the literature. The literature review revealed that most studies present the defects in alphabetical order and do not provide a categorisation system. Moreover, they analyse engine blade failures after a particular event has occurred. There appears to be no existing work that systematically describes root-causes of blade defects and the interrelations.

Notably, the new Taxonomy removes fraud that the lender did not know or could not know about from Tier 1 and places it in Tier 4, thereby removing the requirement that the lender respond in the Loan Review System. HUD also substantially altered the definitions within each defect tier level. These new and revised definitions are broader in some cases, covering additional conduct. Similarly, the causes listed in each defect category have been substantially changed providing for additional and more specific findings in most defects. Hierarchical system of categories designed to assist in the classification of defects. They are hierarchical lists with root causes, failure signs, and other defect-related elements.

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Since usability is a key acceptance criterion of a software product, usability-related issues need to be reported. In this work, a usability issue is defined as any unintended behaviour by the product that is noticed by the user and has an effect on user experience. For example, consider a search job that uses a lot of computer resources.

  • The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.
  • In contrast, an MRO inspector needs more specific information about the defect to make a decision on the part condition, that is, whether a part is to be repaired or replaced with a new one.
  • The severity of a bug is often used as an indicator of how a bug negatively affects system functionality.
  • Considering this limitation, instead of looking at trigger attributes, we study the failure qualifier of the problem.
  • The defect definitions originate from different engine and maintenance manuals and aviation authority documents .

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Aspects that can be used in forming the taxonomy

We sincerely thank staff at the Christchurch Engine Centre for their support and providing insights into visual inspection and blade defects. In particular, we want to thank Tim Coslett, Marcus Wade, Jamie Murray, Matthew Austin, and Blair Robertson. The purpose of this research was to identify defects on aero engine blades, assign possible root-causes, show their inter-relationships, causal links and cascade effects and present it in a coherent manner. In summary, the classification systems for blade defects show a great deal of variability in the types of defect and their description. Experts disagree about whether or not the engine or certain parts shall be cleaned prior to visual inspection . One perspective is that indications of failure, such as cracks, may often be better detectable as they are intensified by the deposits on the part.

Other defects may be more apparent when the deposits are removed, e.g., surface damage. Further, the findings of the induction borescope inspection at the MRO shop determines whether or not to commit to a costly disassembly of the engine. The maintenance of aero engines is intricate and time-consuming and even one maintenance episode may be an appreciable proportion of the engine list price . Consequently, there is an ongoing need for more effective and efficient inspection processes.

Laguna-Camacho, J.R.; Villagran-Villegas, L.Y.; Martinez-Garcia, H.; Juarez-Morales, G.; Cruz-Orduna, M.I.; Vite-Torres, M.; Rios-Velasco, L.; Hernandez-Romero, I. A study of the wear damage on gas turbine blades. Hou, J.; Wicks, B.J.; Antoniou, R.A. An investigation of fatigue failures of turbine blades in a gas turbine engine by mechanical analysis. Next, we evaluated different classification systems and categorised the defects based on the type of damage.

Classification and prioritization of usability problems using an augmented classification scheme

In this study, we expand our previous work by exploring the effect of using categorical features, in addition to stack traces, to predict the severity of bugs. These categorical features include faulty product, faulty component, and operating system. We experimented with other features and observed that they do not improve the severity prediction accuracy.

What matters is that we are collecting, analyzing, and categorizing our past experience and feeding it forward to improve our ability to detect defects. Taxonomies are merely models and, as George Box, the famous statistician, reminds us, “All models are wrong; some models are useful.” Witek, L. Numerical stress and crack initiation analysis of the compressor blades after foreign object damage subjected to high-cycle fatigue. Vardar, N.; Ekerim, A. Failure analysis of gas turbine blades in a thermal power plant.

A total of 41 evaluators from 26 to 55 years of age participated in the evaluation of the OSUDC taxonomy. As shown in Table 5, most of the evaluators are computing students and academic researchers, accounting for 48.8% and 29.3%, respectively. Almost 80% of the evaluators had received training or certification related to usability evaluation/ HCI/ UX. However, as indicated in Table 6, the majority of evaluators had limited familiarity in handling usability defects. Even if formal usability evaluations were to be conducted, OSS projects would still lack an effective mechanism to conduct the evaluations, mainly for two reasons.

definition of defect taxonomy

The damage characteristics include microstructure changes of the part surface material or coating, surfaces debris, wear or material removal and reduced fatigue capability . The degree of abrasion varies from ‘light’ to ‘heavy’ depending upon the extent of reconditioning definition of defect taxonomy required to restore the worn surface. The abrasion effect is accelerated by the presence of foreign material in addition to the detached abrasion material. The defect definitions originate from different engine and maintenance manuals and aviation authority documents .

Automatic prediction of the severity of bugs using stack traces and categorical features

The resulting categorised defects are listed in Table 2. We informally validated this list by discussion with expert maintenance practitioners. This list is considered to be comprehensive for all engine blades, independent of the blade type, engine model and manufacturer. A detailed description of each defect is provided in Appendix Table A1. Then, we integrated our findings in an initial single comprehensive defect list. This list was further enhanced by our own insights gained from observation and personal communication with industry experts.

definition of defect taxonomy

One of the first defect taxonomies was defined by Boris Beizer in Software Testing Techniques. It defines a four-level classification of software defects. The general goal of a defect taxonomy is to reduce the number of product defects that reach customers. Although this goal could be accomplished by implementing excessively long beta and internal testing using certain sets of customers as “permanent” beta … Mishra, R.; Thomas, J.; Srinivasan, K.; Nandi, V.; Raghavendra Bhatt, R. Failure analysis of an un-cooled turbine blade in an aero gas turbine engine. Rao, N.; Kumar, N.; Prasad, B.; Madhulata, N.; Gurajarapu, N. Failure mechanisms in turbine blades of a gas turbine Engine—An overview.

Now, we like to think of defect-based testing as having radar for a certain kind of bug . Instead of using the standard requirements docs or the use cases, we use the defects to base test cases. Abrasion or galling describes a roughened area usually caused by severe chafing or fretting action resulting from slight relative movement of two surfaces under high contact pressure during engine operation.

ISO 9126 Quality Characteristics Taxonomy

This list summarises different terminologies for the same defect and provides a German translation. This may be helpful for the avoidance of confusion as many engine manufacturers and MRO service providers are based in Germany. Defects on engine blades were identified based on the existing literature and engine manuals. The initial result was an unstructured collection of defect terminologies with duplicated information, that is, different terms describing the same type of defect.

Reporting Usability Defects : limitations of Open Source Defect Repositories and Suggestions for Improvement

Each of them is valid and used for different purposes. For example, for investigators of an incident or accident, it is essential to know the root-cause and how such an event can be prevented in the future. In contrast, an MRO facility is interested in the location within the engine where the defect is most likely to occur, to identify parts needing to be replaced and therefore to be purchased.

To create your own taxonomy, first start with a list of key concepts. Make sure the items in your taxonomy are short, descriptive phrases. Keep your users (that’s you and other testers in your organization) in mind. Later, look for natural hierarchical relationships between items in the taxonomy.

The use of the taxonomy has been validated on five real cases of usability defects. However, evaluation results using the OSUDC were only moderately successful. The work provides a single comprehensive illustrated list of engine blade defects, and a standardised defect terminology, which currently does not exist in the industry. It proposes a taxonomy for both engine blade defects and root-causes, and shows that these may be related using an ontology. First, the depth of causation is limited to the second level as shown in Figure 3. This is also the reason why the links in the ontology between causes and defects were only displayed to the second level of causation .

It was interesting to apply the ontological approach to the problem of turbine blades. The ontology was successful in representing the convolution of the two categories, defect versus cause. This is a difficult situation to represent due to the many-to-many causalities, and the temporal and cascade effects. However, ultimately, we were dissatisfied with the ontology, because of the intrinsic limitations of the method, or perhaps of the software. The first is that the ontology cannot handle mathematic calculations or probability representation. This is because the OWL is based on first-order logic and does not have any inherent mechanisms for logic .