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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Environmental science & technology 27 (1993), S. 2181-2189 
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 25 (1986), S. 179-180 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 3
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    Unknown
    Aberdeen, etc. : Periodicals Archive Online (PAO)
    Scottish historical review. 29 (1950) 70 
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Discrete event dynamic systems 2 (1993), S. 235-263 
    ISSN: 1573-7594
    Keywords: timed Petri net ; continuous PN ; asymptotic continuous PN ; asymptotic marking ; critical place
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A Petri net is basically a discrete model. However, continuous Petri nets, such that the markings are real numbers have been defined. Two continuous Petri net models involving time have been drawn up. They differ by the calculation of the instantaneous firing speeds of the transitions. Both can be used to approximate a timed Petri net. The former considers constant firing speeds (CCPN) and is very easy to simulate (few events have to be considered, even when it approximates a timed Petri net with many reachable markings). The latter considers firing speeds depending on the marking (VCPN). Although it provides a better approximation, its simulation is longer because the markings and speeds are given by differential equations. This paper introduces a third model (ACPN) which presents the advantages of the two preceding ones. In most cases, this model represents the asymptotic behavior of the VCPN. Then their precisions are similar. Since the firing speeds of the ACPN are constant, it is as easy to simulate as the CCPN.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International journal of flexible manufacturing systems 3 (1991), S. 275-307 
    ISSN: 1572-9370
    Keywords: Just In Time manufacturing ; Kanban system ; Petri net modeling ; performance evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The success of some Just In Time (JIT) systems has led to a growing interest in Kanban systems, which provide a way to implement a JIT control policy. Much work has recently been devoted to this problem, and especially many models have been developed to evaluate the performance of such systems. In this article, we focus our attention of these existing models. Each author uses his/her own representation, which is not formal in most cases, and so it is often difficult to understand the proposed model and to compare it with others. In this article, we show that Petri nets are well suited to provide a unified modeling of Kanban systems. We first propose a basic model, then show that most models encountered in the literature can easily be represented by a Petri net model. Once such a formal model is obtained, it can then be used to analyze the behavior of the system, both qualitatively and quantitatively. Some preliminary results pertaining to the quantitative analysis are presented at the end of the article.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 424-432 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mixing effects are evaluated for double jet semibatch and continuous stirred precipitators by a model which gives the variation of the primary nucleation flux from the mixing conditions. The predicted trends are compared with results of various authors, including those from a new study of calcium oxalate semibatch double-jet precipitation. Satisfactory qualitative agreement is found for the different chemical systems as a function of feed rate, stirring speed and feed locations for calcium oxalate precipitation. Two types of precipitation systems are demonstrated, depending on the ratio added/tank volume, the initial supersaturations and the intrinsic stiffness factor of a given precipitation. The difference between the two types depends on the increase or reduction of the primary nucleation flux by imperfect mixing with respect to the reference primary nucleation flux obtained with perfect mixing.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1698-1710 
    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 influence of micromixing on precipitation is predicted qualitatively for batch or semibatch precipitations by means of a simplified mixing model, which considers primary nucleation as the main process affected significantly by hydrodynamics. Unwanted micromixing effects are avoided to a maximum in a batch configuration designed to have a volume mixing ratio α close to unity. Using a semibatch precipitator or a batch with a high α value dramatically accentuates mixing interactions. For mixing, changing the feed point location is shown to have much stronger influence than changing the stirring speed and constitutes an efficient test of micromixing. Experimental evidences for these conclusions have been established for calcium oxalate monohydrate batch precipitation. In particular, the early seconds of the reaction (when mainly primary nucleation occurs) have been demonstrated as conditioning the subsequent behavior of the precipitation, even for induction times of a few minutes.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 18 (1995), S. 302-309 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A phenomenological approach to evaluating the agglomeration rate of growing crystals is presented. Crystals larger than the Kolmogoroff microscale collide because of the fluctuating velocity field. Bridges between the crystals form as a result of competition between crystalline growth and the turbulent velocity fluctuations on the opposite sides of the agglomerate.Crystals smaller than the Kolmogoroff microscale collide because of viscous laminar microshear stresses within the same turbulent eddy, are kept close together by Van der Waals forces and are joined together by crystalline bridges that grow between them. The strength of these bridges depends on the supersaturation level during the moments following the collision.These two sets of phenomena lead to two different preferential generation mechanisms for agglomerates. One example involving important agglomeration effects is developed for each case: the crystallization of adipic acid belongs to the first group (large crystals), whereas the precipitation of calcium oxalate monohydrate is typical of the second case (small crystals).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 15 (1992), S. 182-185 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel method for measuring local deviations from perfect mixing of two non-reative tracers is presented. It is based on the partially quenched fluorescence of one fluorescent tracer by a second tracer. When the concentration fluctuations are small, the deviation from the linear behaviour yields the cross-correlation of the fluctuating components of the concentrations of both traces from an - easy to record - average value of fluorescence intensity obtained in the focus of a laser beam. The method was proven to be suitable for measuring these quantities in a 1125 cm3 well-stirred tank as a function of location and stirring speed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 16 (1993), S. 234-237 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A comparison is made between two different methods using laser induced fluorescence spectroscopy for measuring local concentration fluctuations in the same stirred tank. The first method using a single inert fluorescent tracer yields a segregation index quite different from that determined by the second method, which requires two inert tracers, a fluorescent one and a fluorescence quencher. By recalling the theoretical background, it is demonstrated that the characteristic segregation indices should be equal for the experiments under consideration. According to the discussion, it is likely that the double tracer method gives more reliable results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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