Prediction of process forces and stability of end mills with complex geometries

In order to optimize the cutting performance of end mills, the geometry of such cutters is optimized by toolmakers constantly. As a result of geometric changes, process forces can be reduced, i.e. by serrated end mills. Tools with unequal helix angles can lead to an increase of process stability. In this paper, a method to calculate the process forces of end mills with complex geometries is presented. The method for calculating the process forces is designed for the application for stability analysis of end mill cutters with complex geometries. A basic introduction of the method for the stability prediction of such tools is given. Cutting forces of end mills are analyzed at incremental axial depth of cuts to show the influence of the tool geometry on the process forces. The comparison with experimental data verifies this method and shows the influence of further effects on the process forces. Furthermore, stability charts obtained with the Semi-Discretization Method are presented to show the potential of end mills with complex geometries regarding stability improvement.Ministry for Science and Culture of Lower Saxony (MWK

Towards the Usage of MBT at ETSI

In 2012 the Specialists Task Force (STF) 442 appointed by the European Telcommunication Standards Institute (ETSI) explored the possibilities of using Model Based Testing (MBT) for test development in standardization. STF 442 performed two case studies and developed an MBT-methodology for ETSI. The case studies were based on the ETSI-standards GeoNetworking protocol (ETSI TS 102 636) and the Diameter-based Rx protocol (ETSI TS 129 214). Models have been developed for parts of both standards and four different MBT-tools have been employed for generating test cases from the models. The case studies were successful in the sense that all the tools were able to produce the test suites having the same test adequacy as the corresponding manually developed conformance test suites. The MBT-methodology developed by STF 442 is based on the experiences with the case studies. It focusses on integrating MBT into the sophisticated standardization process at ETSI. This paper summarizes the results of the STF 442 work.Comment: In Proceedings MBT 2013, arXiv:1303.037

A new perspective on the competent programmer hypothesis through the reproduction of bugs with repeated mutations

The competent programmer hypothesis states that most programmers are competent enough to create correct or almost correct source code. Because this implies that bugs should usually manifest through small variations of the correct code, the competent programmer hypothesis is one of the fundamental assumptions of mutation testing. Unfortunately, it is still unclear if the competent programmer hypothesis holds and past research presents contradictory claims. Within this article, we provide a new perspective on the competent programmer hypothesis and its relation to mutation testing. We try to re-create real-world bugs through chains of mutations to understand if there is a direct link between mutation testing and bugs. The lengths of these paths help us to understand if the source code is really almost correct, or if large variations are required. Our results indicate that while the competent programmer hypothesis seems to be true, mutation testing is missing important operators to generate representative real-world bugs.Comment: Submitted and under revie

Model-Driven Configuration Management of Cloud Applications with OCCI

International audienceTo tackle the cloud-provider lock-in, the Open Grid Forum (OGF) is developing the Open Cloud Computing Interface (OCCI), a standardized interface for managing any kind of cloud resources. Besides the OCCI Core model, which defines the basic modeling elements for cloud resources, the OGF also defines extensions that reflect the requirements of different cloud service levels, such as IaaS and PaaS. However, so far the OCCI PaaS extension is very coarse grained and lacks of supporting use cases and implementations. Especially, it does not define how the components of the application itself can be managed. In this paper, we present a model-driven framework that extends the OCCI PaaS extension and is able to use different configuration management tools to manage the whole lifecycle of cloud applications. We demonstrate the feasibility of the approach by presenting four different use cases and prototypical implementations for three different configuration management tools

New symmetries of the chiral Potts model

In this paper a hithertho unknown symmetry of the three-state chiral Potts model is found consisting of two coupled Temperley-Lieb algebras. From these we can construct new superintegrable models. One realisation is in terms of a staggered isotropic XY spin chain. Further we investigate the importance of the algebra for the existence of mutually commuting charges. This leads us to a natural generalisation of the boost-operator, which generates the charges.Comment: 19 pages, improved notation, made the text easier to read, corrected some typo