哲学思想在数学发现中的指导作用

数学的发展与哲学是密不可分的 ,早期的几位哲学与数学家将哲学思想溶于数学研究之中 ,导致数学的发现 ,从而推动了数学的发展。本文论述了哲学思想在数学发现中的重要作用     

Flockr展馆

SO–IL是一个概念设计工作室。工作室的业务遍及全球,拥有建筑界、学术界和艺术领域的丰富设计经验。Florian Idenburg和Jing Liu于2007年在布鲁克林成立了工作室,并将它设想为能涵盖不同规模的建筑和不同的建设阶段,成为一个具有创造性的触媒。     

Effects of pigmentation on siloxane–polyurethane coatings and their performance as fouling-release marine coatings

Siloxane–polyurethane paints were formulated and characterized for coating properties and performance as fouling-release (FR) marine coatings. Paints were formulated at 20 and 30 pigment volume concentrations with titanium dioxide, and aminopropyl-terminated poly(dimethylsiloxane) (APT-PDMS) loadings were varied from 0 to 30% based on binder mass. The coatings were characterized for water contact angle, surface energy (SE), gloss, and pseudobarnacle (PB) adhesion. The assessment of the FR performance compared with polyurethane (PU) and silicone standards through the use of laboratory biological assays was also performed. Biofilm retention and adhesion were conducted with the marine bacterium Cellulophaga lytica, and the microalgae diatom Navicula incerta. Live adult barnacle reattachment using Amphibalanus amphitrite was also performed. The pigmented coatings were found to have properties and FR performance similar to those prepared without pigment. However, a higher loading of PDMS was required, in some cases, to obtain the same properties as coatings prepared without pigment. These coatings rely on a self-stratification mechanism to bring the PDMS to the coating surface. The slight reduction in water contact angle (WCA) and increase in pseudobarnacle release force with pigmentation suggests that pigmentation slowed or interfered with the self-stratification mechanism. However, increasing the PDMS loading is an apparent method for overcoming this issue, allowing for coatings having similar properties as those of clear coatings and FR performance similar to those of silicone standard coatings.     

Drought contingency planning

Simulation gaming has the potential to enhance the effectiveness of drought management planning. The Indianapolis water supply system is used to illustrate how. First, the probability of experiencing a severe drought in Indianapolis is examined using historical streamflow data. The effects of such a drought on the municipal water supply system are then analysed using a recently developed simulation model of the Indianapolis water system. Consideration is given to the water resource decision-making problems that might arise under drought conditions, along with a discussion of the benefits of employing simulation gaming in the analysis of these problems. A basic outline for the design of a drought management simulation exercise is presented.     

A Stochastic Kinematic Model of Class Averaging in Single-Particle Electron Microscopy

Single-particle electron microscopy is an experimental technique that is used to determine the 3D structure of biological macromolecules and the complexes that they form. In general, image processing techniques and reconstruction algorithms are applied to micrographs, which are two-dimensional (2D) images taken by electron microscopes. Each of these planar images can be thought of as a projection of the macromolecular structure of interest from an a priori unknown direction. A class is defined as a collection of projection images with a high degree of similarity, presumably resulting from taking projections along similar directions. In practice, micrographs are very noisy and those in each class are aligned and averaged in order to reduce the background noise. Errors in the alignment process are inevitable due to noise in the electron micrographs. This error results in blurry averaged images. In this paper, we investigate how blurring parameters are related to the properties of the background noise in the case when the alignment is achieved by matching the mass centers and the principal axes of the experimental images. We observe that the background noise in micrographs can be treated as Gaussian. Using the mean and variance of the background Gaussian noise, we derive equations for the mean and variance of translational and rotational misalignments in the class averaging process. This defines a Gaussian probability density on the Euclidean motion group of the plane. Our formulation is validated by convolving the derived blurring function representing the stochasticity of the image alignments with the underlying noiseless projection and comparing with the original blurry image.     

Thermal behaviour of poly(lactic acid) in contact with compressed carbon dioxide

BACKGROUND: The thermal behaviour of poly(lactic acid) (PLA) in contact with compressed CO₂ was studied using high‐pressure differential scanning calorimetry. In particular, the effect of annealing below and above the glass transition temperature (T_g) on the glass transition, cold crystallization and melting temperatures was studied systematically as a function of annealing time and pressure. RESULTS: The effect of compressed CO₂ on the thermal properties of PLA is time dependent. Annealing below T_g decreases the temperature and enthalpy of cold crystallization. Similar, but more evident, behaviours are observed when annealing above T_g. Crystallization temperature and enthalpy during cooling decrease with increasing pressure, and the peak is narrower. CONCLUSION: Annealing PLA in the presence of compressed CO₂ accelerates cold crystallization, but retards crystallization during cooling. Copyright © 2009 Society of Chemical Industry     

Metamer density estimated color correction

Color correction is the transformation of response values of scanners or digital cameras into a device- independent color space. In general, the transformation is not unique due to different acquisition and viewing illuminants and non-satisfaction of the Luther–Ives condition by a majority of devices. In this paper we propose a method that approximates the optimal color correction in the sense of a minimal mean error. The method is based on a representative set of reflectance spectra that is used to calculate a special basic collection of device metameric blacks and an appropriate fundamental metamer for each sensor response. Combining the fundamental metamer and the basic collection results in a set of reflectances that follows the density distribution of metameric reflectances if calculated by Bayesian inference. Transforming only positive and bounded spectra of the set into an observer’s perceptually uniform color space results in a point cloud that follows the density distribution of device metamers within the metamer mismatch space of acqcuisition system and human observer. The mean value of this set is selected for color correction, since this is the point with a minimal mean color distance to all other points in the cloud. We present the results of various simulation experiments considering different acquisition and viewing illuminants, sensor types, noise levels, and existing methods for comparison.