611 research outputs found

    Managing the effects of the business cycle in the chemical industry

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    Companies inmany segments of the chemical industry – particularly in themore commoditized segments – are highly exposed to the business cycle. In otherwords, their businesses tend to be quite profitable at the peak butmargins are lowor even negative in downturns of the business cycle. Throughout the article, this phenomenon will be referred to as cyclicality

    Classification of chemicals in the commercial area

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    In the commercial area, classification of chemicals is not as straightforward as in the scientific area. Depending on the perspective taken, different levels can be utilized - moving from segments consisting of individual chemical compounds to the other extreme of segments only defined by the end use of chemicals. In between, there are several other levels in which both perspectives are mixed to a certain degree. The different levels are discussed along with the issues arising from their often simultaneous use. In addition, guidelines are given on the suitability of different levels for specific areas of the chemical industry

    Portfolio Optimization Using SPEA2 with Resampling

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    Proceeding of: Intelligent Data Engineering and Automated Learning – IDEAL 2011: 12th International Conference, Norwich, UK, September 7-9, 2011The subject of financial portfolio optimization under real-world constraints is a difficult problem that can be tackled using multiobjective evolutionary algorithms. One of the most problematic issues is the dependence of the results on the estimates for a set of parameters, that is, the robustness of solutions. These estimates are often inaccurate and this may result on solutions that, in theory, offered an appropriate risk/return balance and, in practice, resulted being very poor. In this paper we suggest that using a resampling mechanism may filter out the most unstable. We test this idea on real data using SPEA2 as optimization algorithm and the results show that the use of resampling increases significantly the reliability of the resulting portfolios.The authors acknowledge financial support granted by the Spanish Ministry of Science under contract TIN2008-06491-C04-03 (MSTAR) and Comunidad de Madrid (CCG10- UC3M/TIC-5029).Publicad

    CVaR minimization by the SRA algorithm

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    Using the risk measure CV aR in �nancial analysis has become more and more popular recently. In this paper we apply CV aR for portfolio optimization. The problem is formulated as a two-stage stochastic programming model, and the SRA algorithm, a recently developed heuristic algorithm, is applied for minimizing CV aR

    Bergman kernel and complex singularity exponent

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    We give a precise estimate of the Bergman kernel for the model domain defined by ΩF={(z,w)Cn+1:ImwF(z)2>0},\Omega_F=\{(z,w)\in \mathbb{C}^{n+1}:{\rm Im}w-|F(z)|^2>0\}, where F=(f1,...,fm)F=(f_1,...,f_m) is a holomorphic map from Cn\mathbb{C}^n to Cm\mathbb{C}^m, in terms of the complex singularity exponent of FF.Comment: to appear in Science in China, a special issue dedicated to Professor Zhong Tongde's 80th birthda

    Evolutionary multi-stage financial scenario tree generation

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    Multi-stage financial decision optimization under uncertainty depends on a careful numerical approximation of the underlying stochastic process, which describes the future returns of the selected assets or asset categories. Various approaches towards an optimal generation of discrete-time, discrete-state approximations (represented as scenario trees) have been suggested in the literature. In this paper, a new evolutionary algorithm to create scenario trees for multi-stage financial optimization models will be presented. Numerical results and implementation details conclude the paper

    Technical note: Introduction of a superconducting gravimeter as novel hydrological sensor for the Alpine research catchment Zugspitze

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    GFZ (German Research Centre for Geosciences) set up the Zugspitze Geodynamic Observatory Germany with a worldwide unique installation of a superconducting gravimeter at the summit of Mount Zugspitze on top of the Partnach spring catchment. This high alpine catchment is well instrumented, acts as natural lysimeter and has significant importance for water supply to its forelands, with a large mean annual precipitation of 2080ĝ€¯mm and a long seasonal snow cover period of 9 months, while showing a high sensitivity to climate change. However, regarding the majority of alpine regions worldwide, there is only limited knowledge on temporal water storage variations due to sparsely distributed hydrological and meteorological sensors and the large variability and complexity of signals in alpine terrain. This underlines the importance of well-equipped areas such as Mount Zugspitze serving as natural test laboratories for improved monitoring, understanding and prediction of alpine hydrological processes. The observatory superconducting gravimeter, OSG 052, supplements the existing sensor network as a novel hydrological sensor system for the direct observation of the integral gravity effect of total water storage variations in the alpine research catchment at Zugspitze. Besides the experimental set-up and the available data sets, the gravimetric methods and gravity residuals are presented based on the first 27 months of observations from 29 December 2018 to 31 March 2021. The snowpack is identified as being a primary contributor to seasonal water storage variations and, thus, to the gravity residuals with a signal range of up to 750ĝ€¯nms-2 corresponding to 1957ĝ€¯mm snow water equivalent measured with a snow scale at an altitude of 2420ĝ€¯m at the end of May 2019. Hydro-gravimetric sensitivity analysis reveal a snow-gravimetric footprint of up to 4ĝ€¯km distance around the gravimeter, with a dominant gravity contribution from the snowpack in the Partnach spring catchment. This shows that the hydro-gravimetric approach delivers representative integral insights into the water balance of this high alpine site. © Copyright

    Copernicus Cal/Val Solution - D2.4 - Systematic Ground-Based Measurements

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    This document aims to map different existing ground-based and air-borne instrumented Cal/Val sites and networks acquiring measurements in a systematic manner, in Europe and worldwide. It does not include all available Cal/Val networks but only those that we interviewed or had enough information available online to include in this report. To meet the needs of satellite Cal/Val, measurements one must adhere to the definition for a Fiducial Reference Measurement (FRM)(Giuseppe Zibordi et al. 2014) and to the principles of the Quality Assurance framework for Earth Observation (QA4EO 2010). The scope of this document is not to evaluate the quality or maturity of the networks/sites that were being interviewed. It only maps the current situation and serves as an input for a later stage of the project. The completed questionnaires that we used to collect the data assembled in this report are not added directly to the document but will be available for project partners for next stage analyses
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