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The R programming language that provides a variety of statistical calculation functions is considered to be one of the programming languages most suitable for artificial intelligence.The correctness of the language implementation is a prerequisite for the correctness of the programs developed with such a language.However,there are inevitably many defects in the R programming language.This paper conducts an empirical study on defects in the R programming language and its core packages.By analyzing 7020 issues,we find that:1) Among all the 35 versions involved in these defects,there are the most defects in R 3.1.2,R 3.0.2 and R 3.5.0,and these defects are primarily distributed in a few components such as Documentation,Graphics,Language.2) The components with higher overall defect priority include Startup,Installation and Analyses,and the components with higher overall defect severity include I/O,Installation and Accuracy.There is a significant intermediate correlation between the priority and severity of the defects.3) About 78% of defects could be repaired within one year.4) Semantic faults are the most frequent root cause of defects,in which the “missing feature” and “processing” are more than others.These findings reveal some laws of defects in the R programming language and its core packages.It can assist developers of the R programming language in improving their development quality,assist maintainers of the R programming language in detecting and repairing defects more effectively,and suggest users of the R programming language evade potential risks.

The destruction of silicone composites irradiated by accelerated electrons is investigated. Experimental results showed that, at irradiation doses of the order of 103 Gy, the mechanical strength of silicon—organic composites is significantly reduced, and doses of the order of 106–107 Gy, their total destruction occurs. This phenomenon was investigated theoretically using a mathematical model for calculating the mechanical characteristics of composites that is based on the idea that their destruction is caused by a gradual accumulation and merging of local defects into large clusters of critical sizes in the bulk of the material. The radiation defects formed by the flow of electrons were calculated by methods developed in the radiation physics of solids. From the concentration and distribution of the defects, the average mechanical characteristics of the composites were determined. [ABSTRACT FROM AUTHOR]

Abstract To gain higher efficiency than that of traditional lattice-matched solar cells, newly designed up-grown metamorphic (UMM) InGaP/InGaAs/Ge solar cells were grown on Ge substrates. The defects in UMM InGaP/InGaAs/Ge can be perfectly controlled, and thus the conversion efficiency exceeds 30%. Similarly, the radiation environment in space could also cause displacement damage in UMM solar cells, causing the degradation of electrical properties. Proton irradiation at 50 keV and 150 keV was tested on the UMM solar cells. Because the top InGaP layer is thick enough, the radiation defects are limited within the top subcell without affecting the underlying subcells. In this research, 50-keV protons cause more serious degradation of short-circuit current, whereas 150-keV protons cause more serious degradation of open-circuit voltage. The difference may be related to the distribution of defects, which is calculated by The Stopping and Range of Ions in Matter (SRIM). Defects in the junction region would cause the decrease in voltage, whereas defects in the surface region could cause degradation of current. As a comparison, lattice-matched GaInP/GaAs/Ge solar cells were also irradiated by low-energy protons. The degradation under 150-keV protons is more serious because the damage peak lies in the middle GaAs layer, which has poor radiation resistance. The degradation under 70-keV proton irradiation proves that a thinner GaInP layer improves the radiation resistance. It is notable that the degradation of short-circuit current and maximum power is influenced by the equivalent displacement damage dose (DDD), but this is not accurate for open-circuit voltage. The artifact signals at 700–750 nm after 50-keV proton irradiation indicate the decrease in shunt resistance of the InGaP subcell during proton irradiation. Highlights • The different degradation behaviors of new UMM InGaP/InGaAs/Ge cells under 50keV or 150keV proton irradiation are compared. • The different degradation behaviors of UMM and ULM InGaP/(In)GaAs/Ge cells under low energy proton irradiation are compared. • The availability of equivalent displacement damage dose method under low energy proton irradiation is discussed. • Artifacts appears at λ =700 nm in the EQE of InGaP after 50 keV proton irradiation. The origin of the artifacts is analyzed. [ABSTRACT FROM AUTHOR]

Cast aluminium alloys, and more widely cast materials, are frequently used in industry. The casting process allows for complex geometries of parts, but, on the downside, often causes materials voids. It is well known these material defects are harmful for material fatigue performances, but the nature of these defects, in a statistical manner, are more seldom studied. This paper aims at proposing a methodology for finding the underlying characteristics of the defect population (size and spatial distribution) and determine their implication on fatigue behaviour in the presence of stress/strain gradients (notched specimens). To do so, various statistical tools are brought from different fields, such as point processes, and applied to experimentally observed defect distributions (by μ CT tomography on virgin test specimens). The population of defects is clearly identified, and it is shown these defects are not randomly distributed, but rather in cluster. It is also shown there is no strong link between the defect size an it's location. Knowing the statistics of the defect population, it is then possible to confront the result of fatigue tests (and the observed initiating defects) with the simulated defect population: the fatigue crack initiation mechanisms, which favour (sub-) surface rather than core initiating defects, reduce the size of the active zone and therefore artificially shift the defect size distribution (by reducing their number). • Spatial distribution of defects by use of point process theory ascertains defects aggregation. • marked point processes, allow to understand the correlation between the location and the defect size. • Clustering slightly affect the critical defect distribution. • the size of clusters impact, the scatter in the number of defects per sample. • the characteristic length of the cluster point process is correlates the highly stressed volume. [ABSTRACT FROM AUTHOR]

lot of effort in the literature has been devoted to define and validate fault taxonomies and models related to different domains, e.g. Service-oriented and Web systems, and properties, e.g. software quality and security. Nevertheless, few attempts were carried out to understand the specific nature of Web bugs and their distribution among the layers of a typical application's architecture-presentation layer, business logic and data logic. In this paper, we present an experimental investigation aimed at studying the distribution of bugs among different layers of Web and Desktop applications. The experiment follows a well-defined procedure executed by six bachelor students. Overall, the analysis considers 1,472 bugs belonging to 20 different applications. The experimental study provides strong evidence that the presentation layer in Web applications is more defect-prone than the analogous layer in Desktop applications. An additional factor influencing the distribution of defects is represented by the application domain. [ABSTRACT FROM AUTHOR]

Electrical properties in the subthreshold region are studied in two types of field effect transistors: laser crystallized-polysilicon thin film transistors (LC-TFTs) and solid phase crystallized-polysilicon thin film transistors (SPC-TFTs). For LC-TFT the active layer is crystallized by using one shot of a very large area excimer laser with a fluence of 600 mJ/cm2, whereas the active layer for SPC-TFT is crystallized by a thermal annealing at 600 °C in vacuum. LC polysilicon layer exhibits a higher degree of crystallinity than the SPC one.Electrical measurements on the TFTs are performed from room temperature to 120 °C. The analysis of the transfer characteristics shows that the subthreshold current is thermally activated with a different gate voltage dependence for each type of TFTs. The electrical behavior in the subthreshold region is correlated with the quality of the polysilicon active layer. For LC-TFT, conduction is mainly due to thermal emission of carriers over intergranular barrier energy, and it is convenient with a discrete distribution of defects in the active layer, mainly located at the grain boundaries. On the other hand, for SPC-TFTs, a mechanism of multiple-trapping and/or generation/recombination process of carriers from defects, rather uniformly distributed in the active layer, predominates in the electrical conduction. [Copyright &y& Elsevier]