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Feature models have become a de facto standard for representing variability in software product lines. UVL (Universal Variability Language) is a language which expresses the features, dependencies, and constraints between them. This language is written in plain text and follows a syntactic structure that needs to be processed by a parser. This parser is software with specific syntactic rules that the language must comply with to be processed correctly. Researchers have datasets with numerous feature models. The language description form of these feature models is tied to a version of the parser language. When the parser is updated to support new features or correct previous ones, these feature models are often no longer compatible, generating incompatibilities and inconsistency within the dataset. In this paper, we present UVL Sentinel. This tool analyzes a dataset of feature models in UVL format, generating error analysis reports, describing those errors and, eventually, a syntactic processing that applies the most common solutions. This tool can detect the incompatibilities of the feature models of a dataset when the parser is updated and tries to correct the most common syntactic errors, facilitating the management of the dataset and the adaptation of their models to the new version of the parser. Our tool was evaluated using a dataset of 1,479 UVL models from different sources and helped semi-automatically fix 185 warnings and syntax errors., Comment: Presented at 6th International Workshop on Languages for Modelling Variability (MODEVAR'24) (arXiv:cs/2402.15511)

Constraint-based applications attempt to identify a solution that meets all defined user requirements. If the requirements are inconsistent with the underlying constraint set, algorithms that compute diagnoses for inconsistent constraints should be implemented to help users resolve the "no solution could be found" dilemma. FastDiag is a typical direct diagnosis algorithm that supports diagnosis calculation without predetermining conflicts. However, this approach faces runtime performance issues, especially when analyzing complex and large-scale knowledge bases. In this paper, we propose a novel algorithm, so-called FastDiagP, which is based on the idea of speculative programming. This algorithm extends FastDiag by integrating a parallelization mechanism that anticipates and pre-calculates consistency checks requested by FastDiag. This mechanism helps to provide consistency checks with fast answers and boosts the algorithm's runtime performance. The performance improvements of our proposed algorithm have been shown through empirical results using the Linux-2.6.3.33 configuration knowledge base., Comment: presented at The 37th AAAI Conference on Artificial Intelligence, AAAI'23, Washington DC, USA

First principles calculations through density functional theory (DFT)+$U$ method were performed to assess the effect of Li interstitial doping on the optoelectronic properties of NiO and of cubic, hexagonal, and monoclinic WO$_3$. The implications on the structural and electronic properties and their relationship with the optical properties, such as dielectric response and absorption coefficient in the context of electrochromism, are discussed. Li interstitial doping (i.e., electron doping) turns these materials metallic-like even for low Li concentration ($x<0.083$). In metallic-like materials, optical properties are largely influenced by intraband transitions. Compared to NiO, Li-doped NiO shows larger absorption in the visible region while, with respect to WO$_3$, Li-doped WO$_3$ exhibits an increment in absorption in the whole spectrum, particularly, in the infrared region. These results help to understand the changes in optical properties observed in electrochromic devices based on these materials., Comment: 13 pages, 8 figures, research paper

Many domains require scalable algorithms that help to determine diagnoses efficiently and often within predefined time limits. Anytime diagnosis is able to determine solutions in such a way and thus is especially useful in real-time scenarios such as production scheduling, robot control, and communication networks management where diagnosis and corresponding reconfiguration capabilities play a major role. Anytime diagnosis in many cases comes along with a trade-off between diagnosis quality and the efficiency of diagnostic reasoning. In this paper we introduce and analyze FlexDiag which is an anytime direct diagnosis approach. We evaluate the algorithm with regard to performance and diagnosis quality using a configuration benchmark from the domain of feature models and an industrial configuration knowledge base from the automotive domain. Results show that FlexDiag helps to significantly increase the performance of direct diagnosis search with corresponding quality tradeoffs in terms of minimality and accuracy., Comment: Preprint, cite as: A. Felfernig. R. Walter, J. Galindo, D. Benavides, M. Atas, S. Polat-Erdeniz, and S. Reiterer. Anytime Diagnosis for Reconfiguration. Journal of Intelligent Information Systems, vol. 51, pp. 161-182, 2018

Variability models (e.g., feature models) are a common way for the representation of variabilities and commonalities of software artifacts. Such models can be translated to a logical representation and thus allow different operations for quality assurance and other types of model property analysis. Specifically, complex and often large-scale feature models can become faulty, i.e., do not represent the expected variability properties of the underlying software artifact. In this paper, we introduce DirectDebug which is a direct diagnosis approach to the automated testing and debugging of variability models. The algorithm helps software engineers by supporting an automated identification of faulty constraints responsible for an unintended behavior of a variability model. This approach can significantly decrease development and maintenance efforts for such models., Comment: to appear in the ICSE'21 Proceedings, 5 pages, 2 figures

We investigate the effect of post-deposition annealing (for temperatures from 848 K to 1273 K) on the chemical properties of crystalline Ta$_2$O$_5$ films grown on Si(100) substrates by radio frequency magnetron sputtering. The atomic arrangement, as determined by X-ray diffraction, is predominately hexagonal ($\delta$-Ta$_2$O$_5$) for the films exposed to heat treatments at 948 K and 1048 K; orthorhombic ($\beta$-Ta$_2$O$_5$) for samples annealed at 1148 K and 1273 K; and amorphous for samples annealed at temperatures below 948 K. X-ray photoelectron spectroscopy for Ta $4f$ and O $1s$ core-levels were performed to evaluate the chemical properties of all films as a function of annealing temperature. Upon analysis, it is observed the Ta $4f$ spectrum characteristic of Ta in Ta$^{5+}$ and the formation of Ta-oxide phases with oxidation states Ta$^{1+}$, Ta$^{2+}$, Ta$^{3+}$, and Ta$^{4+}$. The study reveals that the increase in annealing temperature increases the percentage of the state Ta$^{5+}$ and the reduction of the others indicating that higher temperatures are more desirable to produce Ta$_2$O$_5$, however, there seems to be an optimal annealing temperature that maximizes the O\% to Ta\% ratio. We found that at 1273 K the ratio slightly reduces suggesting oxygen depletion., Comment: 7 pages, 1 table, 6 figures. arXiv admin note: text overlap with arXiv:1804.02067, arXiv:1704.05514

We designed and developed a desktop ac susceptometer for the characterization of materials. The system consists of a lock-in amplifier, an ac function generator, a couple of coils, a sample holder, a computer system with a designed software in freeware C++ code, and an Arduino card coupled to a bluetooth module. The Arduino/bluetooth serial interface allows the user to have a connection to almost any computer and thus avoids the problem of connectivity between the computer and the peripherals such as the lock-in amplifier and the function generator. The bluetooth transmitter/receiver used is a commercial device which is robust and fast. These new features reduce the size and increment the versatility of the susceptometer for it can be used with a simple laptop. To test our instrument we performed measurements on magnetic materials and show that the system is reliable at both room temperature and cryogenic temperatures (77 K). The instrument is suitable for any physics or engineering laboratory either for research or academic purposes., Comment: 14 pages, 10 Figures

The effect of argon ion bombardment on the chemical properties of crystalline Ta$_2$O$_5$ films grown on Si(100) substrates by radio frequency magnetron sputtering was investigated by X-ray photoelectron spectroscopy. All samples were irradiated for several time intervals [(0.5, 3, 6, 9) min] and the Ta $4f$ and O $1s$ core levels were measured each time. Upon analysis at the surface of the films, we observe the Ta $4f$ spectrum characteristic of Ta$_2$O$_5$. Irradiated samples exhibit the formation of Ta suboxides with oxidation states Ta$^{1+}$, Ta$^{2+}$, Ta$^{3+}$, Ta$^{4+}$, and Ta$^{5+}$. Exposing the films, after ion bombardment, to ambient for some days stimulates the amorphous phase of Ta$_2$O$_5$ at the surface suggesting that the suboxides of Ta are unstable. Using a sputtering simulation we discuss that these suboxides are largely generated during ion bombardment that greatly reduces the oxygen to tantalum ratio as the irradiation time increases. The computer simulation indicates that this is due to the high sputtering yield of oxygen., Comment: 12 pages, 8 figures

We investigate the effect of annealing temperature on the crystalline structure and physical properties of tantalum-pentoxide films grown by radio frequency magnetron sputtering. For this purpose, several tantalum films were deposited and the Ta$_2$O$_5$ crystalline phase was induced by exposing the samples to heat treatments in air in the temperature range from (575 to 1000)$^\circ$C. Coating characterization was performed using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and UV-VIS spectroscopy. By X-ray diffraction analysis we found that a hexagonal Ta$_2$O$_5$ phase generates at temperatures above $675^\circ$C. As the annealing temperature raises, we observe peak sharpening and new peaks in the corresponding diffraction patterns indicating a possible structural transition from hexagonal to orthorhombic. The microstructure of the films starts with flake-like structures formed on the surface and evolves, as the temperature is further increased, to round grains. We found out that, according to the features exhibited in the corresponding spectra, Raman spectroscopy can be sensitive enough to discriminate between the orthorhombic and hexagonal phases of Ta$_2$O$_5$. Finally, as the films crystallize the magnitude of the optical band gap increases from 2.4 eV to the typical reported value of 3.8 eV., Comment: 9 pages, 8 Figures, 2 Tables

Many project-specific languages, including in particular filtering languages, are defined using non-formal specifications written in natural languages. This leads to ambiguities and errors in the specification of those languages. This paper reports on an industrial experiment on using a tool-supported language specification framework (K) for the formal specification of the syntax and semantics of a filtering language having a complexity similar to those of real-life projects. This experimentation aims at estimating, in a specific industrial setting, the difficulty and benefits of formally specifying a packet filtering language using a tool-supported formal approach., Comment: In Proceedings F-IDE 2016, arXiv:1701.07925