Reproducibility and replicability of software defect prediction studies

© 2018 Elsevier B.V. Context: Replications are an important part of scientific disciplines. Replications test the credibility of original studies and can separate true results from those that are unreliable.Objective: In this paper we investigate the replication of defect prediction studies and identify the characteristics of replicated studies. We further assess how defect prediction replications are performed and the consistency of replication findings.Method: Our analysis is based on tracking the replication of 208 defect prediction studies identified by a highly cited Systematic Literature Review (SLR) [1]. We identify how often each of these 208 studies has been replicated and determine the type of replication carried out. We identify quality, citation counts, publication venue, impact factor, and data availability from all 208 SLR defect prediction papers to see if any of these factors are associated with the frequency with which they are replicated.Results: Only 13 (6%) of the 208 studies are replicated. Replication seems related to original papers appearing in the Transactions of Software Engineering (TSE) journal. The number of citations an original paper had was also an indicator of replications. In addition, studies conducted using closed source data seems to have more replications than those based on open source data. Where a paper has been replicated, 11 (38%) out of 29 studies revealed different results to the original study.Conclusion: Very few defect prediction studies are replicated. The lack of replication means that it remains unclear how reliable defect prediction is. We provide practical steps for improving the state of replication

Analysis of stress-strain state of bucket wheel excavator revolving platform structure: Fundament of efficient reconstruction

Rotorni bageri čine okosnicu sistema mehanizacije površinskih kopova Njihova eksploatacija u ekstremno teškim uslovima prouzrokuje otkaze delova noseće konstrukcije (plastične deformacije, prsline, pukotine, lomovi). Kao konkretni primeri, u radu su najpre prikazani izgledi tipičnih oštećenja konstrukcija obrtnih platformi bagera TAKRAF SRs 1200×24/4 (400 kW) + VR. Potom su izloženi postupci proračuna njihove konstrukcije čiju osnovu čine dve etape: formiranje konačno elementnih mreža i analiza opterećenja. Sprovođenjem izložene procedure proračuna, oblikovano je konstrukciono rešenje primenjeno prilikom rekonstrukcije obrtnih platformi dva bagera pomenutog tipa tokom 2005. godine. O valjanosti pristupa problemu i uspešnosti rešenja rekonstrukcije uverljivo govori podatak da su, nakon sanacije i rekonstrukcije, bageri otkopali više od 5 000 000 m3 otkrivke, a da pri tome, u zonama rekonstrukcije, nisu konstatovani bilo kakvi defekti konstrukcija obrtnih platformi.Bucket wheel excavators (BWE) are a part and parcel of the mechanization system in open pits. Their exploitation in heavy duty conditions causes failures of supporting structural parts (plastic deformations, cracks fractures, break-ages). As a real example, the paper first presents appearance of typical damages of revolving platform structures for BWE TAKRAF SRs 1200×24/4 (400 kW) + VR. Subsequently, techniques for calculating their structure are presented, whose basis is made in two stages: set up of finite element mesh and analysis of loads. The structural solution is developed by conducting the presented calculation procedure, and is applied during reconstruction of revolving platforms (2005) on two BWEs mentioned before. Validity of problem approach and efficiency of reconstruction solution is found in the fact that after reconstruction and repair BWE have excavated more than 5 000 000 m3 of barren soil, while at reconstruction zones no defects of revolving platform structures have been detected

Analysis of stress-strain state of bucket wheel excavator revolving platform structure: Fundament of efficient reconstruction

Rotorni bageri čine okosnicu sistema mehanizacije površinskih kopova Njihova eksploatacija u ekstremno teškim uslovima prouzrokuje otkaze delova noseće konstrukcije (plastične deformacije, prsline, pukotine, lomovi). Kao konkretni primeri, u radu su najpre prikazani izgledi tipičnih oštećenja konstrukcija obrtnih platformi bagera TAKRAF SRs 1200×24/4 (400 kW) + VR. Potom su izloženi postupci proračuna njihove konstrukcije čiju osnovu čine dve etape: formiranje konačno elementnih mreža i analiza opterećenja. Sprovođenjem izložene procedure proračuna, oblikovano je konstrukciono rešenje primenjeno prilikom rekonstrukcije obrtnih platformi dva bagera pomenutog tipa tokom 2005. godine. O valjanosti pristupa problemu i uspešnosti rešenja rekonstrukcije uverljivo govori podatak da su, nakon sanacije i rekonstrukcije, bageri otkopali više od 5 000 000 m3 otkrivke, a da pri tome, u zonama rekonstrukcije, nisu konstatovani bilo kakvi defekti konstrukcija obrtnih platformi.Bucket wheel excavators (BWE) are a part and parcel of the mechanization system in open pits. Their exploitation in heavy duty conditions causes failures of supporting structural parts (plastic deformations, cracks fractures, break-ages). As a real example, the paper first presents appearance of typical damages of revolving platform structures for BWE TAKRAF SRs 1200×24/4 (400 kW) + VR. Subsequently, techniques for calculating their structure are presented, whose basis is made in two stages: set up of finite element mesh and analysis of loads. The structural solution is developed by conducting the presented calculation procedure, and is applied during reconstruction of revolving platforms (2005) on two BWEs mentioned before. Validity of problem approach and efficiency of reconstruction solution is found in the fact that after reconstruction and repair BWE have excavated more than 5 000 000 m3 of barren soil, while at reconstruction zones no defects of revolving platform structures have been detected

Urban Growth and Urbanization of Sofiа, Belgrade and Rome: the Interaction between Urban Planning and the Market

The paper explores the problems of sustainable and resilient development of the cities in Eastern and South-east Europe on the examples of Sofia, Belgrade and Rome and their urban regions. The research draws comparisons to the forms, patterns and mechanisms of their development.Editors: Atanas Kovachev, Aleksandar D Slaev, Diliana Daskalov