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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 207-215 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An on-line estimation technique for multiple specific growth rates is proposed. Time-varying tuning parameters are used to obtain constant estimation error dynamics in spite of strongly varying process dynamics commonly encountered in bioprocesses. This approach simplifies the tuning of the algorithm to a pole placement procedure. Application of the method is illustrated through the study of the baker's yeast fedbatch process. Guidelines for selection of measured state variables are given in relation to the performance of the estimation method.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1751-1760 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The experimental validation of on-line estimation of multiple specific growth rates for the bakers' yeast fed-batch process is presented. Pole placement based parameter estimation combined with an asymptotic biomass observer constitute the basic algorithm. The full process model being ill-conditioned for estimation using the available measured state variables, the use of two partial models related to two different states of the process is suggested. An alternating procedure between two sets of estimation algorithms designed from the partial models is proposed. The performance of the alternating procedure is validated both with simulated and experimental data. The accuracy of the estimates of the three specific growth rates involved in this process is verified according to two criteria based on the respiratory quotient and on the evaluation of the ethanol production/consumption rate.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The transesterification reaction catalyzed by dibutyltin oxide has been used to crosslink miscible blends (at about 200°C) of ethylene vinyl acetate (EVA) and ethylene methyl acrylate (EMA) copolymers. Then, microwave heating at 2.45 GHz with the fundamental TE01 mode was used for activation of this crosslinking reaction. The microwave treatment was carried out in a continuous process through a resonant cavity on line with a twin screw extruder equipped with a strip die or a circular die, which imposed the shape of the samples in the waveguide. Therefore, a shape factor due to the geometry of the samples and their orientation with respect to the electromagnetic field was defined. Last, this technique was applied to the microwave crosslinking of an EVA/EMA blend dispersed in a polypropylene matrix and consequently offers a new route to control the morphology of the polymer blends.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 193-201 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A generalized linear dynamic model or singular model, for which the standard state space representation and the Kalman filtering cannot be applied, is used to develop a new algorithm to solve the linear dynamic material balance problem. This algorithm is based on the method developed in the steady-state case and leads to a recursive scheme, which is very useful in real-time processing. It reduces the computational problem such as singularities and round-off errors that may occur in complex systems. Convergence conditions are given and verified for the dynamic material balance case.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1449-1460 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Many industrially significant microbial products are produced during secondary metabolism by fungal pellets. Most models of mycelial pellet growth, however, consider only the primary growth phase. During secondary metabolism, the whiterot fungus Phanerochaete chrysosporium produces extra-cellular lignin peroxidases and manganese-dependent peroxidases which have been implicated in the degradation of lignin and various xenobiotics. This unstructured kinetic model for mycelial pellet cultures of P. chrysosporium describes the culture dry weight, respiration, glucose consumption, nutrient nitrogen uptake, pellet size and oxygen effectiveness factor during the lag, primary growth, secondary metabolic, and death phases. During secondary metabolism, the intraparticle diffusion of oxygen limits metabolism. Parameters for respiration during secondary metabolism are validated using three separate measurements: 1. by measuring oxygen concentration profiles in mycelial pellets using oxygen microelectrodes; 2. by measuring the depletion of oxygen from the culture fluid using a respirometer; and 3. by measuring the daily evolution of carbon dioxide. The physiological state of the mycelial pellets is predicted for various culture conditions and is related to the production of LIP and MNP during secondary metabolism.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1544-1550 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Plastic profile die design is a complex task because of cross section area and shape changes occurring after die exit. Dimensions of the profile are increased by the extrudate swell phenomenon and decreased by drawdown and shrinkage. An experimental study on the effect of processing conditions on extrudate swell and on the shape of a rectangular profile was done for rigid poly(vinyl chloride), PVC, and high density polyethylene, HDPE, resins. Extrudate swell was found to be a strong decreasing function of residence time in the die and also, for short dies, of entrance geometry. For PVC, equilibrium swell increased with melt temperature. The differences in swelling for the two polymers are explained with the help of creep/recovery data obtained on a stress rheometer. Drawdown, die land length, and melt temperature were shown to have an important effect on the shape of a rectangular profile. Decreasing the die land and increasing the melt temperature had the effect of increasing preferably the thickness while drawdown, by inhibiting the swelling, decreased the thickness.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The stereoselective substitution of chlorine atoms was used to graft anthracene and phenyl groups onto the poly(vinyl chloride) (PVC) backbone as ultraviolet (UV) tracers for the assessment of the residence time distribution (R.T.D) of PVC chains during the extrusion of rigid and plasticized PVC. The residence time distribution obtained using these-grafted tracers was compared with that obtained using a free UV tracer (anthracene). The polymeric tracer had a narrower R.T.D and a shorter mean residence time. This difference of behavior between a free and grafted tracers was attributed to the compatibility of these tracers with the PVC.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Transesterification may be used to crosslink a copolymer such as ethylene vinyl acetate with poly(ethylene acrylate-co-propylene) in the presence of dibutyltin oxide as a catalyst. A rheological study of the mechanism of this exchange reaction has been made: The kinetics of the crosslinking reaction was determined by studying the time and temperature dependence of the dynamic storage modulus G′(t, T)ω. Kinetic curves obtained for different reactive blends (EVA, PP/EVA, and PPf/EVA) allowed for the evaluation of the activation energy of the reaction and, thus, specified the appropriate parameters (temperature and time) for carrying out this reaction in a molten state.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Conducting polyaniline is found to be suitable for several lithographic applications. With the use of onium salts, polyaniline is made radiation sensitive and shown to be a high resolution conducting photo and electron-beam resist. Conducting lines of 0.25 μm have been patterned with e-beam irradiation. Thin films of conducting polyaniline are found to be effective discharge layers for e-beam lithography. Insulating resist systems charge during e-beam exposure, which results in pattern displacements. When polyaniline is used as a conducting layer below the imaging resist, no pattern displacements are observed. Polyaniline is also shown to eliminate charging during the high resolution inspection and dimensional measurements of X-ray and optical masks by scanning electron microscopy (SEM) when used as a coating on top of the mask. In addition, polyaniline can be used for electrolytic and electroless type metallization processes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    ISSN: 0193-7197
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Substitution reactions are an appropriate way to attach chemical functions to polymer chains for improving properties and to diversify the application of polymer materials. The stereoselective substitution of chlorine atoms affords a useful way to plasticize polyvinychloride (PVC) by attaching appropriate plasticizing functions (ester group) such as isooctylthiosalicylate. Thus, the substitution of chlorine atoms of PVC by reactant bearing plasticizing groups was carried out in a continuous mixing apparatus such as a twin screw extruder. This continuous chemical engineering process taking place in the extruder is studied as the function of the residence time distribution (RTD) measured by a UV method. This function combined with the kinetics of the chemical reaction allows to define a new function G as the distribution of the extent of conversion by analogy with the RTD function.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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