When does Subagging Work?

We study the effectiveness of subagging, or subsample aggregating, on regression trees, a popular non-parametric method in machine learning. First, we give sufficient conditions for pointwise consistency of trees. We formalize that (i) the bias depends on the diameter of cells, hence trees with few splits tend to be biased, and (ii) the variance depends on the number of observations in cells, hence trees with many splits tend to have large variance. While these statements for bias and variance are known to hold globally in the covariate space, we show that, under some constraints, they are also true locally. Second, we compare the performance of subagging to that of trees across different numbers of splits. We find that (1) for any given number of splits, subagging improves upon a single tree, and (2) this improvement is larger for many splits than it is for few splits. However, (3) a single tree grown at optimal size can outperform subagging if the size of its individual trees is not optimally chosen. This last result goes against common practice of growing large randomized trees to eliminate bias and then averaging to reduce variance

Inclusion of rapeseed and pumpkin seed cakes in diets for Murciano-Granadina goats alters the fatty acid profile of milk

The objective of this research was to assess the effects of including oil-rich feedstuffs in diets for lactating goats on the fatty acid (FA) profile of their milk. Thirty-six Murciano-Granadina goats were randomly assigned to three treatment groups, namely a control diet (CTRL), a diet based on whole rapeseed (RS), and a diet based on pumpkin seed cake (PSC). The diets were composed of 1 kg hay (70 % Italian ryegrass, 30% alfalfa) and 1.24 kg concentrate, and were formulated to be isoenergetic and isonitrogenous. Milk yield and its contents of protein, fat and lactose did not differ significantly among the groups. However, including oil-rich feeds in the diet altered the fatty acid profile of the milk significantly, decreasing its saturated fatty acid (SFA) content and increasing its content of unsaturated fatty acids (UFAs). Effects on polyunsaturated fatty acids (PUFAs), conjugated linoleic acid (CLA), and the n-6 to n-3 ratio depended on the source of dietary lipids. The PSC augmented diet increased the relative amount of PUFAs and fatty acid methyl esters (FAME) in milk (+25 %) significantly In comparison with CTRL, whereas the RS diet produced a limited and statistically insignificant increase (+7.5%). The concentration of CLA was higher in milk from does fed the PSC diet, whereas the n-6 to n-3 ratio was lower in milk from does fed RS. These preliminary results form the basis for developing premium dairy products that are enriched in fatty acids that are more favourable for human health

MAGNUS--An Ultra-High Specific Torque PM Axial Flux Type Motor with Flux Focusing and Modulation

Axial flux permanent magnet (AFPM) synchronous motors are attractive for low speed direct drive systems because of their high specific torque. The present paper proposes a novel axial flux machine topology, called MAGNUS, obtained by combining a yokeless central stator type NS arrangement with two external high polarity spoke-rotors, resulting in very high flux concentration. The stator, which includes main and auxiliary teeth for air-gap profiling has a small number of concentrated coils. Two stator configurations are discussed, the first, a yokeless construction with coils wound around the teeth, and the second with coils placed around the stator core in a Gramme ring arrangement. Feasible slot pole combinations are identified. High torque densities are achievable owing to torque magnification achieved by air-gap profiling as well as flux concentration. Initial analysis indicates that this machine presents higher torque than a YASA machine, which currently holds a record for torque density

Axial-Flux PM Synchronous Machines with Air-Gap Profiling and Very High Ratio of Spoke Rotor Poles to Stator Concentrated Coils

Permanent magnet machines including a magnetic gearing effect are attractive for low-speed high-torque applications. This paper proposes a dual-stator axial-flux machine topology with a high ratio for the number of rotor poles to concentrated stator coils. The stator consists of a relatively small number of teeth, with each tooth including multiple smaller/auxiliary teeth. The rotor employs spoke-type permanent magnets, which result in high flux concentration, thereby further improving the torque density. The paper discusses the principle of operation of the proposed machine topology. Finite element results on example designs with 6 stator teeth, each having 2 and 3 auxiliary teeth, and with 20, 32, and 34 rotor poles are presented, respectively. Other feasible slot-pole combinations are also identified

Ensemble machine learning model for automated asteroid detection

The potential threat of Near Earth Objects (NEO) requires a constant survey of the night sky to discover potentially dangerous objects and assess their future impact odds. Several ongoing surveys relying on human operators or automated techniques exist. One such example is the EURONEAR blink mini-survey project which over time developed from a pure manual approach to detecting asteroids to semi-automatic methods (NEARBY) using image processing and service-oriented approaches. In this paper, we propose an extension of NEARBY based on an ensemble model comprising three state-of-art machine learning models, some used in similar approaches. The proposed model is designed for a binary classification problem where candidate images may contain an asteroid in their center. Validation on a real-life dataset comprising 11,000 images shows that our ensemble model is capable of recovering about 55% of the asteroids missed by the previous NEARBY automated process while at the same time having a 0.88 recall on the asteroids already detected by NEARBY. Used together with NEARBY our model increased the detection rate from 89% to 95%

Projects as Knowledge Swirls in the Technological Innovation: Romania's Situation

The present paper uses as research basis a new way of thinking regarding the relation between innovation and knowledge - the Knowledge Flow Percolation Model (KFPM). In this model’s center, human beings are seen as thinking electrons, both consuming and generating knowledge flows. Through the interdependent actions of individuals, knowledge circulates inside organizations, allowing them to innovate in order to obtain competitive advantages. But there is a wide range of barriers which impede the creation and movement of flows in the model grid and consequently, hinder their change into innovation. The solution proposed by this paper as one of the most adequate instruments to make KFPM more spreadable is the project. On this basis, in an empirical study, we try to demonstrate the hypothesis of the positive influence of projects, as knowledge swirls, on the development of innovative skills which will help solving problems in the organization, creating and widening of knowledge and reducing the barriers in knowledge transfer.This work was supported by the project “Post-Doctoral Studies in Economics: training program for elite researchers – SPODE” co-funded from the European Social Fund through the Development of Human Resources Operational Programme 2007-2013, contract no. POSDRU/89/1.5/S/61755

A new measurement of J/psi suppression in Pb-Pb collisions at 158 GeV per nucleon

We present a new measurement of J/psi production in Pb-Pb collisions at 158 GeV/nucleon, from the data sample collected in year 2000 by the NA50 Collaboration, under improved experimental conditions with respect to previous years. With the target system placed in vacuum, the setup was better adapted to study, in particular, the most peripheral nuclear collisions with unprecedented accuracy. The analysis of this data sample shows that the (J/psi)/Drell-Yan cross-sections ratio measured in the most peripheral Pb-Pb interactions is in good agreement with the nuclear absorption pattern extrapolated from the studies of proton-nucleus collisions. Furthermore, this new measurement confirms our previous observation that the (J/psi)/Drell-Yan cross-sections ratio departs from the normal nuclear absorption pattern for semi-central Pb-Pb collisions and that this ratio persistently decreases up to the most central collisions.Comment: 19 pages, 10 figures. Submitted to Eur. Phys. J.

J/psi azimuthal anisotropy relative to the reaction plane in Pb-Pb collisions at 158 GeV per nucleon

The J/$\psi$ azimuthal distribution relative to the reaction plane has been measured by the NA50 experiment in Pb-Pb collisions at 158 GeV/nucleon. Various physical mechanisms related to charmonium dissociation in the medium created in the heavy ion collision are expected to introduce an anisotropy in the azimuthal distribution of the observed J/$\psi$ mesons at SPS energies. Hence, the measurement of J/$\psi$ elliptic anisotropy, quantified by the Fourier coefficient v$_2$ of the J/$\psi$ azimuthal distribution relative to the reaction plane, is an important tool to constrain theoretical models aimed at explaining the anomalous J/$\psi$ suppression observed in Pb-Pb collisions. We present the measured J/$\psi$ yields in different bins of azimuthal angle relative to the reaction plane, as well as the resulting values of the Fourier coefficient v$_{2}$ as a function of the collision centrality and of the J/$\psi$ transverse momentum. The reaction plane has been estimated from the azimuthal distribution of the neutral transverse energy detected in an electromagnetic calorimeter. The analysis has been performed on a data sample of about 100 000 events, distributed in five centrality or p$_{\rm T}$ sub-samples. The extracted v$_{2}$ values are significantly larger than zero for non-central collisions and are seen to increase with p$_{\rm T}$.Comment: proceedings of HP08 conference corrected a typo in one equatio