Learning programs by learning from failures

Machine Learning - We describe an inductive logic programming (ILP) approach called learning from failures. In this approach, an ILP system (the learner) decomposes the learning problem into three...     

Variability in estimation of suprathreshold small color differences

Intraobserver and interobserver variability in perceptual small color difference evaluation are known but are rarely analyzed phenomena. They raise the question if humans are equipped to make reliable and uniform estimates of this kind. Data from two recent well‐controlled studies show that intraobserver and, particularly, interobserver variability are surprisingly large. The use of a gray reference scale in place of a single gray reference pair has a small normative effect on the estimate. A large interobserver variability in the estimated magnitude of chromatic differences compared with achromatic reference pairs remains, with an average ratio between largest and smallest estimate of over 3:1 and ratios for individual observers and sample pairs ranging up to 28:1. No correlation was found between the reliability of judgment and the judged magnitude of difference: highly reliable observer groups are not more consistent. Relative reliability of estimate was found inversely related to magnitude of perceived difference. Consequences of these results for the development of improved color difference formulas are discussed. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 367–374, 2009     

Effects of different Mg fertilizer sources on the magnesium availability in soils

Pot experiments with different soils were conducted to determine the effect of different Mg fertilizer sources on magnesium availability. The sources studied included Kieserite (MgSO₄ H₂O), a synthetic magnesium sulphate (SMS) with variable content of crystal water and a calcined magnesite (Mg-oxide). The three magnesium fertilizers vary greatly in their solubility in water, affecting the availability to plants once applied to the soil. Whereas Kieserite dissolved gradually and SMS immediately, Mg-oxide released only insignificant amounts of Mg in cool water (20 °C) after intensive stirring. Due to the fact that these dissolution properties may distinctly affect Mg availability in soils, Kieserite as a standard magnesium source was tested against a slow release Mg-oxide in the fine and the coarse form. Soil extraction of samples taken from 0–10 and 10–20 cm depths at 4, 8 and 12 weeks after applying the fertilizers to the soil surface revealed that the rate at which Mg appeared in the available pool (CaCl₂ extracts) varied significantly between Mg sources. Mg availability from Kieserite was much greater than from Mg-oxide. Nutrient availability from Mg-oxide depended on the fineness of the material, i.e. the coarser the less available. Maize grown as test plant in the pots revealed a 10.6% larger yield and 19.6% larger Mg uptake in Kieserite than in Mg-oxide treated pots. High solubility of a fertilizer under high rainfall conditions, however, may also affect the Mg availability through large losses occurring by Mg leaching. Therefore, in a second experiment, the behaviour of surface applied magnesium fertilizers, Kieserite versus a quickly dissolving synthetic magnesium sulphate (SMS) was studied, using an Ultisol (Serdang Series soil from Malaysia). A simulation of high rainfall by excessive irrigation of 20 mm per day over a period of 16 days to a water saturated soil revealed that the amount of Mg lost by leaching differed between the two Mg sources tested. The lowest amount with 8.7% of the applied Mg was lost in the Kieserite treatment at the low application rate and the highest with 22.3% in the SMS treatment at the high application rate. It is concluded that a gradual but strong release to match plants requirements is the most desired characteristic to maximize crop uptake and minimize losses.     

Travel Reports and Photography in Early Photographically Illustrated Books

Abstract

Abstract A previous article¹ dealt with some of the first books illustrated by tipped-in photographs, or else by early photomechanical procedures, with subject matter drawn from the fields of microscopy, medicine and astronomy. The present essay is concerned with technically similar publications, on topics of a more social nature.     

Restricted Least Squares Estimation of the Spectra and Concentration of Two Unknown Constituents Available in Mixtures

The problem considered is the identification of two unknown chemical compounds and the estimation of their proportions in a set of unknown mixtures of the two compounds, given data that are vectors of measurements on their mixtures. It is assumed that the expected value of a mixture vector is an unknown convex linear combination of two unknown component vectors and least squares estimation is used to obtain a set of possible solutions of the mixing proportions and the component vectors. Obtaining a unique solution requires additional constraints or information. The solution set is interpreted geometrically and examples involving amino acids and light absorbance data are given.     

Mechanically activated minerals as a sink for CO2

CO₂ removal from exhaust gasses from burning of fossil fuels is a political issue. If undertaken on a large scale, enormous amounts of carbon dioxide will have to be taken care of. This paper investigates how mechanical activation of olivine and other Ca or Mg containing silicates can increase the mineral’s reactivity. Tests by grinding in a planetary mill have been done to investigate the effects of mechanical activation and other surface changes. The reactivity towards HCl and CO₂ has been determined as a function of grinding variables. Prolonged dry milling of olivine resulted in highly aggregated products, which were more reactive with respect to dissolution in acid than their respective BET surface areas would suggest. The initial breaking of bonds appears to give more reactivity on an energy usage basis than longer time activation. Most mechanical activation testwork so far has been carried out in batch mode. The result is diminishing effect of activation with increased grinding time. Continuous grinding and simultaneous reaction with some sort of classification may offer a chance of removing reaction products as soon as they are formed, giving a more energy effective process.     

Morphology of the transparent IPN‐like system PE: (BMA‐co‐S)

In the study of interpenetrating polymer networks (IPN)‐like systems consisting of polyethylene (PE) and butyl methacrylate (BMA)–styrene (S) copolymer PE/(BMA‐co‐S), the effect of the crosslinker on the morphology of IPN by using electron microscopy and atomic force microscopy (AFM) was investigated. The IPN‐like system PE/(BMA‐co‐S) represents a two‐phase system with finely dispersed domains of crosslinked PE matrix. The interphase between dispersed domains and PE matrix is inhomogeneous and is considered the most interpenetrated part of this IPN‐like system. The size of the domains decreases with the content of crosslinker used. The AFM micrographs allowed the observation of PE lamellae with lengths of about 25 nm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2615–2620, 2001     

Neue Berechnungsformel für das IT von Walzprofilen und Berechnung der Schubspannungen

A new formula for the I_T of hot‐rolled I‐sections and the determination of the shear stresses. In this paper a new formula for hot‐rolled I‐sections and the determination of the torsional cross‐section property I_T is presented. The results of the new formula are more precise than the ones specified previously. In addition, a method to determine the maximum shear stresses in hot‐rolled profiles is presented.     

Instationäres 3D Thermo‐mechanisches Modell für Beton

Transient 3D thermo‐mechanical Model for Concrete In the present paper a transient three‐dimensional thermo‐mechanical model for concrete is presented. For a given boundary conditions, temperature distribution is calculated by employing a three‐dimensional transient thermal finite element analysis. The thermal properties of concrete are assumed to be constant and independent of the stress‐strain distribution. In the thermo‐mechanical model for concrete the total strain tensor is decomposed into pure mechanical strain, free thermal strain and load induced thermal strain. The mechanical strain is calculated by using temperature dependent microplane model for concrete [1]. The model is implemented into a three‐dimensional FE code. The performance of headed stud anchors exposed to fire was studied. For a given geometry of a concrete member and for a constant concrete properties a three‐dimensional transient thermal FE analysis was carried out for three embedment depths and for four thermal load histories. The analysis shows that the resistance of anchors can be significantly reduced if they are exposed to fire. The largest reduction of the load capacity was obtained for anchors with relatively small embedment depth. The numerical results agree well with the available experiments.