Search results for "CPM"
showing 5 items of 25 documents
Effect of Heating Time and Temperature on the Chemical Characteristics of Biochar from Poultry Manure
2014
Poultry manure (PM) chars were obtained at different temperatures and charring times. Chemical-physical characterization of the different PM chars was conducted by cross-polarization magic angle spinning (CPMAS) (13)C NMR spectroscopy and thermal analysis. CPMAS (13)C NMR spectra showed that the chemical composition of PM char is dependent on production temperature rather than on production duration. Aromatic and alkyl domains in the PM chars obtained at the lowest temperatures remained unchanged at all heating times applied for their production. The PM char obtained at the highest temperature consisted only of aromatic structures having chemical nature that also appeared invariant with hea…
Interactions between 2-Aminobenzothiazole and Natural Organic Matter as Evidenced by CPMAS Nitrogen-15 NMR Spectroscopy
2009
Cross-polarization magic angle spinning (CPMAS) 15N nuclear magnetic resonance (NMR) spectroscopy was used to study the interactions between 2-aminobenzothiazole (ABT) and natural organic matter in the presence of the natural enzyme laccase and synthetic air. Through the use of synthesized model compounds, we were able to confirm previous findings by CPMAS 13C NMR spectroscopy that showed the formation of covalent amide bonds. We also provide evidence of the presence of two additional H bonds between ABT and the natural organic matter. Both H bonds involved the amino and thiazole groups of ABT.
Effect of ramp size and sample spinning speed on CPMAS 13C NMR spectra of soil organic matter
2011
Abstract Cross polarization (CP) magic angle spinning (MAS) 13C NMR spectroscopy is a solid state NMR technique widely applied to study the chemical composition of natural organic matter. In high magnetic fields (>7 T), fast sample spinning is required in order to reduce the influence of spinning sidebands underlying other chemical shift regions. As the spinning speed increases, the Hartmann–Hahn matching profiles break down into a series of narrow matching bands. In order to account for this instability variable amplitude cross polarization techniques (e.g. VACP, ramp-CP) have been developed. In the present study, we experimentally verified the stability of the Hartmann–Hahn condition unde…
Critical Path Analysis with Imprecise Activities Times
2018
The aim of the paper is to present the conceptual framework related to critical path analysis with imprecise activity duration times. This article is motivated by the fact that most approaches to project planning are deterministic. In reality, the problem is accompanied by uncertainty and risk associated with dealing with imprecise data. Taking this uncertainty into account when performing analyses and calculations not only helps to better project planning, but also to expand the applicability of project scheduling methods under real-life or uncertain conditions. The major contribution of this paper is the development of a novel approach to critical path analysis in the presence of uncertai…
Szacowanie czasu realizacji projektu przy nieprecyzyjnych zmiennych
2017
The paper presents the essence and significance of the project time estimation under uncertainty and risk using ordered fuzzy numbers. The proposed approach is based on a fuzzy model of uncertainty using ordered fuzzy numbers as imprecise data – duration times. The presented extended critical path method is a new approach that has not been presented so far in the literature of the subject. The authors present the implementation of the approach on an example. The advantages of the proposed approach have been outlined in the paper. The proposed approach can find practical applications in decision-making problems under conditions of risk and uncertainty, supporting decision-makers in the plann…