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排序方式: 共有699条查询结果,搜索用时 15 毫秒
1.
Norman Fenton Martin Neil William Marsh Peter Hearty Łukasz Radliński Paul Krause 《Empirical Software Engineering》2008,13(5):499-537
Standard practice in building models in software engineering normally involves three steps: collecting domain knowledge (previous
results, expert knowledge); building a skeleton of the model based on step 1 including as yet unknown parameters; estimating
the model parameters using historical data. Our experience shows that it is extremely difficult to obtain reliable data of
the required granularity, or of the required volume with which we could later generalize our conclusions. Therefore, in searching
for a method for building a model we cannot consider methods requiring large volumes of data. This paper discusses an experiment
to develop a causal model (Bayesian net) for predicting the number of residual defects that are likely to be found during
independent testing or operational usage. The approach supports (1) and (2), does not require (3), yet still makes accurate
defect predictions (an R
2 of 0.93 between predicted and actual defects). Since our method does not require detailed domain knowledge it can be applied
very early in the process life cycle. The model incorporates a set of quantitative and qualitative factors describing a project
and its development process, which are inputs to the model. The model variables, as well as the relationships between them,
were identified as part of a major collaborative project. A dataset, elicited from 31 completed software projects in the consumer
electronics industry, was gathered using a questionnaire distributed to managers of recent projects. We used this dataset
to validate the model by analyzing several popular evaluation measures (R
2, measures based on the relative error and Pred). The validation results also confirm the need for using the qualitative factors
in the model. The dataset may be of interest to other researchers evaluating models with similar aims. Based on some typical
scenarios we demonstrate how the model can be used for better decision support in operational environments. We also performed
sensitivity analysis in which we identified the most influential variables on the number of residual defects. This showed
that the project size, scale of distributed communication and the project complexity cause the most of variation in number
of defects in our model. We make both the dataset and causal model available for research use. 相似文献
2.
A hybrid ab initio path integral molecular dynamics/bosonic path integral Monte Carlo simulation method has been developed, implemented and tested, which allows for the reactive simulations of molecules, clusters or complexes solvated by superfluid 4He. The simulation takes into account “on-the-fly” the electronic structure and thus the chemical reactivity of the solutes, in conjunction with the Bose–Einstein statistics, and thus the superfluid character of this peculiar solvent. This enables investigations into cryochemical reactions taking place in helium nanodroplets, such as those used in helium nanodroplet isolation (HENDI) spectroscopy. 相似文献
3.
Applying the boundary element method to electrochemical calculations of primary current distribution
The computation of primary current distribution using the boundary element method has been analysed. A numerical example has been included. Values obtained numerically have been compared with those obtained experimentally. A fairly good accuracy has been observed. Some computational problems occurring when using the boundary element method for electrochemical problems have been discussed. 相似文献
4.
5.
6.
We investigate quantitative extensions of modal logic and the modal μ-calculus, and study the question whether the tight connection between logic and games can be lifted from the qualitative
logics to their quantitative counterparts. It turns out that, if the quantitative μ-calculus is defined in an appropriate way respecting the duality properties between the logical operators, then its model
checking problem can indeed be characterised by a quantitative variant of parity games. However, these quantitative games
have quite different properties than their classical counterparts, in particular they are, in general, not positionally determined.
The correspondence between the logic and the games goes both ways: the value of a formula on a quantitative transition system
coincides with the value of the associated quantitative game, and conversely, the values of quantitative parity games are
definable in the quantitative μ-calculus. 相似文献
7.
8.
Mateusz Schabikowski Magdalena Laskowska Pawe Kowalczyk Andrii Fedorchuk Emma Szri-Doroghzi Zoltn Nmeth Dominika Ku
ma Barbara Gawdzik Aleksandra Wypych Karol Kramkowski ukasz Laskowski 《International journal of molecular sciences》2022,23(15)
In this article, we describe the antimicrobial properties of a new composite based on anodic aluminium oxide (AAO) membranes containing propyl-copper-phosphonate units arranged at a predetermined density inside the AAO channels. The samples were prepared with four concentrations of copper ions and tested as antimicrobial drug on four different strains of Escherichia coli (K12, R2, R3 and R4). For comparison, the same strains were tested with three types of antibiotics using the minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests. Moreover, DNA was isolated from the analysed bacteria which was additionally digested with formamidopyrimidine-DNA glycosylase (Fpg) protein from the group of repair glycosases. These enzymes are markers of modified oxidised bases in nucleic acids produced during oxidative stress in cells. Preliminary cellular studies, MIC and MBC tests and digestion with Fpg protein after modification of bacterial DNA suggest that these compounds may have greater potential as antibacterial agents than antibiotics such as ciprofloxacin, bleomycin and cloxacillin. The described composites are highly specific for the analysed model Escherichia coli strains and may be used in the future as new substitutes for commonly used antibiotics in clinical and nosocomial infections in the progressing pandemic era. The results show much stronger antibacterial properties of the functionalised membranes on the action of bacterial membranes in comparison to the antibiotics in the Fpg digestion experiment. This is most likely due to the strong induction of oxidative stress in the cell through the breakdown of the analysed bacterial DNA. We have also observed that the intermolecular distances between the functional units play an important role for the antimicrobial properties of the used material. Hence, we utilised the idea of the 2D solvent to tailor them. 相似文献
9.
M. BUSŁOWICZ 《International journal of control》2013,86(6):1311-1321
The paper gives sufficient conditions for instability of linear systems of both the neutral and retarded types with commensurate and non-commensurate time delays. The conditions are given in terms of time delays and coefficients of the characteristic quasi-polynomials of these systems. Illustrative examples are presented. 相似文献
10.
STANISŁAW K. DUDA 《International journal of control》2013,86(5):1387-1399
This paper presents a new theory for determining dynamic output feedback of the least order for a linear, time-invariant, controllable and observable SIMO system, such that poles of the closed-loop system lie in a given region Γ in the complex plane. When some poles have prespecified stationary locations in the complex plane, dynamic output feedback is obtained in the sense that the remaining poles lie in Γ This theory applies to continuous-time as well as discrete-time systems. Here a design algorithm for complete system realization and an illustrative example are given. 相似文献