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  • 1
    Digitale Medien
    Digitale Medien
    Information theory of chromatography and titration
    Amsterdam : Elsevier
    Analytica Chimica Acta 277 (1993), S. 325-331 
    Details
    ISSN: 0003-2670
    Schlagwort(e): FUMI ; Information theory ; Liquid chromatography ; Mutual information function ; Titrimetry
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://linkinghub.elsevier.com/retrieve/pii/0003-2670(93)80445-Q
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  • 2
    Digitale Medien
    Digitale Medien
    Theoretical analysis on the limitations of the open-circuit voltage of a hydrogenated amorphous silicon p-i-n solar cell (1986)
    Springer
    Applied physics 39 (1986), S. 277-286 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 86.30 ; 72.40
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We have made theoretical studies on the limitation of the open-circuit voltageV oc of a hydrogenated amorphous silicon (a-Si:H) p-i-n type solar cell. The effects of the tail states in the a-Si:H i layer and of the interface recombination are discussed in detail. The opencircuit voltage increases when the distribution of the tail states is sharp and/or the capture cross sections of these states are small. This is because the recombination rate of photogenerated carriers and/or the density of space charge due to trapped carriers in these states become low in these conditions. These effects of the tail states on the value ofV oc become pronounced when the built-in potential of the p-i-n junction is high. The decrease in the effective recombination velocity of carriers at the p/i and n/i interfaces results in an increase ofV oc. This increase becomes remarkable when the effects of the tail states on the value ofV oc are small. Both the sharp distribution of tail states and the small value of the interface recombination velocity are necessary to increase considerably the value ofV oc. We show the conditions of the material parameters necessary to obtain an open-circuit voltage of 1.0 V.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00617273
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  • 3
    Digitale Medien
    Digitale Medien
    Theoretical analysis of trapping and recombination of photogenerated carriers in amorphous silicon solar cells (1985)
    Springer
    Applied physics 37 (1985), S. 153-164 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 86.30 ; 72.40 ; 73.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We have made theoretical studies on the trapping and recombination of photogenerated carriers in hydrogenated amorphous silicon (a-Si∶H) p-i-n solar cells. We discuss in detail the following points: 1) The limitations of the assumptions in the previous analysis. It has been clarified that the single-level Shockley-Read-Hall model for carrier recombination and the treatment of trap occupation in terms of quasi-Fermi levels are inadequate for exact analysis. 2) The superlinear dependence of carrier recombination rate on the free-carrier density which can explain the enhancement of photo-induced changes ina-Si∶H under high intensity light. 3) The estimation of capture cross section of the tail states ina-Si∶H. We show that the charged and neutral tail states have rather small capture cross sections of less than 10−16 cm2 and of less than 10−19 cm2, respectively. 4) The effect of the recombination of photogenerated (PG) carriers at the p/i and the n/i interfaces. We estimate the recombination velocityS of PG carriers at these interfaces to be about 103 cm/s. It has been also clarified that the decrease inS is effective to improve the cell performance, especially the open circuit voltage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00617500
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  • 4
    Digitale Medien
    Digitale Medien
    Validity of quasi-static capacitance-voltage measurements applied to hydrogenated amorphous silicon diodes (1986)
    Springer
    Applied physics 40 (1986), S. 171-176 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 73.60 ; 71.20 ; 86.30
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We have reexamined the validity of quasi-static capacitance-voltage (C-V) measurements when applied to hydrogenated amorphous silicon (a-Si: H) diodes. Displacement currents with the application of a linear ramp voltage to an a-Si:H Schottky diode exhibit a slow response with time constants ranging 0.1–1 s which cannot be measured completely by the conventional measurements. The measured capacitance and the effective density of gap states obtained from the measurement depend on the timing of current observation even when the small value of the order of 0.01 V/s is chosen for the ramp rate. We propose a possible means to realize the true quasi-staticC-V measurement of a-Si:H diodes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00617400
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  • 5
    Digitale Medien
    Digitale Medien
    An information theory-based evaluation of stationary phases developed for optical resolution of amino acids (1993)
    Springer
    Chromatographia 37 (1993), S. 156-158 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Chromatography, general ; Information theory ; Stationary phases ; Optical resolution of amino acids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Naphthylethylurea multiple-bonded chiral stationary phases prepared for the optimal resolution of p-bromophenylcarbamyl derivatives of enantiomeric amino acids are examined from the viewpoint of information theory. The criterion used is the function of mutual information (FUMI) which describes the precision of analysis as a function of peak shape (area and width), overlap and noise level. The length of the polyethyleneamine spacer in the chiral stationary phases is evaluated by the precision (FUMI) calculated from the peak shape and overlap. The best column is defined as the one which gives the highest precision. The temperature effect on the precision is also examined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02275853
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  • 6
    Digitale Medien
    Digitale Medien
    Total chromatographic optimization (TOCO) I. Simultaneous optimization of many variables in liquid chromatography (1990)
    Springer
    Chromatographia 30 (1990), S. 85-90 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Optimization of variables ; Information theory ; Kalman filter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The following chromatographic variables are totally optimized based on the recently developed information theory of optimization: mobile phase composition, column length, flow rate, wavelength, and the amount of internal standard. The optimal internal standard is selected from among six candidates. Two types of optimal conditions (Φ- and ϑ-optimals) are proposed: the Φ-optimal is defined as the most precise analysis (the maximal Φ) while the ϑ-optimal is the most efficient (rapid) analysis (the maximal ϑ). The observation times for the determination of an antipyretics mixture (three components) in liquid chromatography are ca. 50 s for the ϑ-optimal and ca. 8 min for the Φ-optimal. The reliability of the Φ- and ϑ-optimals is verified by experiments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02270454
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  • 7
    Digitale Medien
    Digitale Medien
    Feasible solutions for optimization problems involving unresolved peaks using retention prediction and information theory (1991)
    Springer
    Chromatographia 31 (1991), S. 554-560 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Chromatography, general ; Optimization ; Information theory ; Kalman filter ; Retention prediction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary This paper treats optimization problems involving unresolved component peaks with the information measure FUMI (Function ofMutualInformation) as a criterion. The LC analysis of 20 PTH-amino acids is taken as an example of the optimization of mobile phase composition, column length and temperature. The quantitative structure-retention relationship is adopted for the simulation and for the establishment of feasible solutions of the problems. The applicability of the FUMI theory is further extended by solving the above optimization problems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02279475
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  • 8
    Digitale Medien
    Digitale Medien
    Mathematical structure of chromatographic optimization based on information theory: II. Analytical role of chromatographic variables (1991)
    Springer
    Chromatographia 31 (1991), S. 374-380 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Chromatography, general ; Optimization ; Information theory ; Kalman filter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The influence of variables Z (mobile phase composition X, column length L, etc.) on chromatographic analysis is studied in terms of the two separate stages of the whole optimization process. In the first stage, peak separation is the central concern and the resolution Rs can be related to Shannon information φj of peak $$j:\frac{{\partial \phi _j }}{{\partial Z}} = C\frac{{\partial R_s }}{{\partial Z}}$$ where C is a coefficient (〉0). In the second stage, only chromatograms with no peak overlap are considered and Rs is not connected with φj. The analytical role of Z is evaluated by comparing the signs and magnitudes of the derivatives of the information, φj, and its transmission rate, ϑj, with respect to Z in both stages.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262195
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  • 9
    Digitale Medien
    Digitale Medien
    Mathematical structure of chromatographic optimization based on information theory: I. Effect of mobile phase composition on precision (1991)
    Springer
    Chromatographia 31 (1991), S. 367-373 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Chromatography, general ; Optimization ; Information theory ; Kalman filter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The influence of mobile phase composition X on the precision of liquid-chromatographic analysis is interpreted in terms of the derivate of the mutual information φ for peak j with respect to X, dφj/dX. The sign and magnitude of dφj/dX depend on the operational conditions of X or on the details of chromatograms (e.g., resolutions Rs), but dφj/dX always indicates the direction of X toward more information φj. The sensitivity function sj(=1/(kj+1)) is examined on the basis of information theory. Optimization is formulated as a nonlinear programming problem.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262194
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  • 10
    Digitale Medien
    Digitale Medien
    A simple optimization strategy based on Rs-minimum and information theory of chromatography (1990)
    Springer
    Chromatographia 30 (1990), S. 367-370 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Optimization of variables ; Information theory ; Kalman filter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A simple optimization method based on the well-known Rs-minimum method and on the information theory of FUMI Φ is proposed. Resolution (Rs), peak area and height (or width) are the only parameters necessary for the calculation of the information Φ and information flow ϑ. The most precise analysis can be selected as the chromatogram having maximal ϑ. Mobile phase composition, column length, flow rate, detection wavelength, amount of internal standard, etc. can be optimized by this method.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02328499
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