Using Sensitivity as a Method for Ranking the Test Cases Classified by Binary Decision Trees

Usually, data mining projects that are based on decision trees for classifying test cases will use the probabilities provided by these decision trees for ranking classified test cases. We have a need for a better method for ranking test cases that have already been classified by a binary decision tree because these probabilities are not always accurate and reliable enough. A reason for this is that the probability estimates computed by existing decision tree algorithms are always the same for all the different cases in a particular leaf of the decision tree. This is only one reason why the probability estimates given by decision tree algorithms can not be used as an accurate means of deciding if a test case has been correctly classified. Isabelle Alvarez has proposed a new method that could be used to rank the test cases that were classified by a binary decision tree [Alvarez, 2004]. In this paper we will give the results of a comparison of different ranking methods that are based on the probability estimate, the sensitivity of a particular case or both

Reduction of the value of information sharing as demand becomes strongly auto-correlated

Information sharing has been identified, in the academic literature, as one of the most important levers to mitigate the bullwhip effect in supply chains. A highly-cited article on the bullwhip effect has claimed that the percentage inventory reduction resulting from information sharing in a two level supply chain, when the downstream demand is autoregressive of order one, is an increasing function of the autoregressive parameter of the demand. In this paper we show that this is true only for a certain range of the autoregressive parameter and there is a maximum value beyond which the bullwhip ratio at the upstream stage is reduced and the percentage inventory reduction resulting from information sharing decreases towards zero. We also show that this maximum value of the autoregressive parameter can be as high as 0.7 which represents a common value that may be encountered in many practical contexts. This means that large benefits of information sharing cannot be assumed for those Stock Keeping Units (SKUs) with highly positively auto-correlated demand. Instead, equally careful analysis is needed for these items as for those SKUs with less strongly auto-correlated demand

Les commentaires bibliques de l’école rhénane au xvie siècle :sources, exégèse et herméneutique

Dans les années 1525-1545, dans l’aire rhénane, paraît une série de commentaires scripturaires dans lesquels, non seulement le texte massorétique, mais aussi les sources juives médiévales (Rashi, Abraham Ibn Ezra, David Qimhi, Nahmanide) sont utilisés pour établir, non seulement l’exégèse, mais aussi l’herméneutique chrétiennes du texte biblique. Dans les années 1970, Gerald Hobbs et Bernard Roussel ont mis en évidence la cohérence de ces commentaires au sein d’une « école rhénane d’exégèse » […]

The biology of the mosquitoes in Kansas and a key for their identification

Call number: LD2668 .T4 1937 D4

Sinkage, trim, drag of a common freely floating monohull ship

A practical method — well suited for early ship design and hull form optimization — for estimating the sinkage, the trim and the drag of a freely-floating common monohull ship at moderate Froude numbers F ≤ 0.45 is considered. The sinkage and the trim are realistically estimated via two alternative simple methods: an experimental approach based on an analysis of experimental measurements (involving no flow computations), and a numerical approach based on a practical linear potential-flow theory (the Neumann-Michell theory) that only requires simple flow computations for the hull surface ΣH of the ship at rest. The drag is also estimated in a simple way, based on the classical Froude decomposition into viscous and wave components: well-known semi empirical expressions for the friction drag, the viscous drag and the drag due to hull roughness are used, and the wave drag is evaluated via the Neumann-Michell theory. The drag is more sensitive to the hull position than the sinkage and the trim. Accordingly, it must be computed for a ‘dynamic’ ship hull surface ΣH that accounts for sinkage and trim effects, although the hull surface ΣH does not need to be very precise. In fact, the total drag computed for the hull surface ΣH chosen as the hull surface ΣH predicted by the numerical approach, or as st 1 the hull surface ΣH predicted by the even simpler experimental approach, are nearly identical. Moreover, the drag of the hull surface ΣH and the (nearly identical) drag of the hull surface ΣH 1 a are significantly higher, and also in much better agreement with experimental measurements, than the drag of the hull surface Σ

A global approximation to the green function for diffraction-radiation of regular water waves in deep water

The Green function of the theory of diffraction radiation of time-harmonic (regular) waves by an offshore structure, or a ship at low speed, in deep water is considered. The Green function G and its gradient ∇G are expressed in the usual manner as the sum of three com- ponents that correspond to the fundamental free-space singularity, a non-oscillatory local flow, and waves. Simple approximations that only involve elementary continuous functions (algebraic, exponential, logarithmic) of real arguments are given for the local flow components in G and G. These approximations are global approximations valid within the entire flow region, rather regions as can be found in the literature

Effects of Section Geometry on the Energy-saving Rate of PBCF and Model/full-scale Correlation - A CFD Study

The steady flows and hydrodynamic performances of a propeller without and with the Propeller Boss Cap Fins (PBCFs) are simulated by solving the Reynolds-averaged Navier-Stokes (RANS) equations using the software package STAR-CCM+. To determine a suitable grid setting, a grid convergence study is carried out first by changing the grid sizes separately in the sub-domains enclosing the propeller blades and the PBCFs. The CFD investigation into the energy-saving rate of the PBCFs with systematically varied section profiles at model-scale shows the PBCFs with modified ‘NACA M7’ section geometry performs better than the flat plate in energy-saving effect. Full-scale simulations are also carried out using typical PBCF geometries investigated at model scale, and the results are compared with model-scale ones to evaluate the Reynolds scale effects on the energy-saving rate. The hydrodynamic forces acting on the propeller blades, the PBCFs, and the boss cap are compared to explore the mechanism behind the scale effects on the PBCFs. The study indicates that the scale effect positively influences the energy-saving effect of all the PBCFs investigated, while the flat-plate PBCFs benefit more from the scale effect

Comparison of Classical And Weakly-singular Representations of Freesurface Potential Flows

Within the potential-flow framework, a flow in a domain is determined in terms of the flow at the boundary surface of the flow domain by means of a classical boundary-integral representation, which defines the flow potential фin terms of a Green function G and its gradient ▼G. An alternative flow representation is the weakly-singular representation (which defines фin terms of G and a vector Green function G associated to G via the relation ▼×G = ▼G) given by the authors for diffraction radiation by a ship advancing in regular waves. The alternative mathematical representations of far-field waves associated with the classical and weakly-singular potential representations are compared here in the special case of steady flows

Influence de la forme de la carène sur les caractéristiques de la vague d’étrave

On étudie par la méthode du bateau mince la forme de la vague d’étrave d’une famille de bateaux sans bulbe dépendant de 4 paramètres qui prennent en compte l’angle d’étrave et l’angle de tulipage. Les principales caractéristiques de la vague d’étrave, hauteur à l’étrave, hauteur et distance du maximum, passage à zéro sont présentés sous forme de courbes qui peuvent être directement exploités sans calcul au stade de l’avant-projet de navire