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  • Flexible manufacturing systems  (3)
  • precursor chemistry  (3)
  • Genetic maps  (2)
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  • 1
    Digitale Medien
    Digitale Medien
    Determination of Particle Size and Shape during the Hydrolysis of Pb(Zr0.3Ti0.7)O3 Precursor Solutions (1998)
    Springer
    Journal of sol gel science and technology 11 (1998), S. 141-152 
    Details
    ISSN: 1573-4846
    Schlagwort(e): precursor chemistry ; lead zirconate titanate ; hydrolysis ; PCS ; SAXS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The formation and growth of polymeric particles during the hydrolysis and condensation of PbZr0.3Ti0.7 O3 (PZT 30/70) sol-gel precursor solutions have been investigated by using photon correlation spectroscopy (PCS), small angle X-ray scattering (SAXS) and by measuring their rheological properties. The measurements showed that the growth of the particles in the transition of PZT sol to gel followed a simple polymerisation process. Solution A (containing ‘by-products’) and Solution B (‘by-products’ removed) displayed a similar plot of logarithmic viscosity against logarithmic time, indicating that the particles in both solutions have similar structures after hydrolysis. The changes in viscosity and particle size with time were described by single logarithmic growth models. However, the increasing rate of logarithmic particle size in Solution B is higher than that in Solution A. A model for the form of the aggregates is discussed which is applicable to PZT organometal-particle aggregation process in systems with acetic acid as a modifier.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008641429895
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  • 2
    Digitale Medien
    Digitale Medien
    A Comparison of the Nanostructure of Lead Zirconate, Lead Titanate and Lead Zirconate Titanate Sols (1999)
    Springer
    Journal of sol gel science and technology 15 (1999), S. 13-22 
    Details
    ISSN: 1573-4846
    Schlagwort(e): precursor chemistry ; lead zirconate titanate ; hydrolysis ; PCS ; SAXS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Sol-gel processing has been widely used for the fabrication of lead zirconate titanate (PZT) thin films. To successfully and consistently make high quality thin films for different applications, we must develop a fundamental understanding of the structures of the sols. In this study, the characters of lead titanate (PT) and lead zirconate (PZ)sols were studied by measuring the rheological properties and particle sizes in them and comparing their behaviours. The average particle sizes in unhydrolysed PT, PZ and PZT sols are 11.5, 1.0, and 6.0 nm, respectively. PT sol has the highest rate of hydrolysis. It gels at about 24 h after hydrolysis. PZ and PZT sols have a quite similar feature in hydrolysis. The reasons for the differences in the hydrolysis behaviour of the different types of sol are discussed in terms of a model which indicates that the inhomogeneous sols consist of 5 to 6 nm PT particles surrounded by much smaller PZ particles, which tend to dominate the sol behaviour.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008759520087
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  • 3
    Digitale Medien
    Digitale Medien
    Heterometallic lead-titanium oxyalkoxide precursors to lead titanate thin films (1994)
    Springer
    Journal of sol gel science and technology 2 (1994), S. 29-34 
    Details
    ISSN: 1573-4846
    Schlagwort(e): precursor chemistry ; lead titanate ; thin films ; hydrolysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Two lead titanium oxyalkoxides with composition Pb2Ti4O2(O2CCH3)2(OC2H5)14 and Pb2Ti2O2(O2CCH3)2(OCH(CH3)2)8 have been isolated and characterised by elemental analysis, IR, 207Pb NMR and molecular weight measurements. X-ray structural analysis of the 1:2 complex confirmed the presence of two Pb2Ti2O units which are linked by a common Pb···Pb edge and are held together by alkoxide and acetate bridges. The acetate groups have migrated from the Pb to the Ti centres during the reaction. Hydrolysis of the 1:1 Pb/Ti complex produced clear gels providing the H2O/complex ratio was less than 4. Heat treatment of the gel results in loss of residual organics below 400°C. The XRD pattern indicates the presence of the pyrochlore and perovskite phases after heating at 500°C but the sample is poorly crystalline. Complete conversion to the perovskite phase of lead titanate occurs on heating to 600°C for 1 hour. Thin films of lead titanate were deposited by dip-coating a solution of this complex in isopropanol. Analyses of the films, carried out using electron microprobe, Scanning Auger Spectroscopy and Rutherford Backscattering, indicated that they were of excellent quality, crystalline after heating at 600°C and with relatively sharp substrate-coating interface.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00486209
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  • 4
    Digitale Medien
    Digitale Medien
    Analysis of the barley and rice genomes by comparative RFLP linkage mapping (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 541-551 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words  Synteny ; Orthologous evolution ; Genetic maps ; Triticeae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract   Comparative genetic mapping of rice and barley, both major crop species with extensive genetic resources, offers the possibility of uniting two well-established and characterized genetic systems. In the present study, we screened 229 molecular markers and utilized 110 polymorphic orthologous loci to construct comparative maps of the rice and barley genomes. While extensive chromosomal rearrangements, including inversions and intrachromosomal translocations, differentiate the rice and barley genomes, several syntenous chromosomes are evident. Indeed, several chromosomes and chromosome arms appear to share nearly identical gene content and gene order. Seventeen regions of conserved organization were detected, spanning 287 cM (24%) and 321 cM (31%) of the rice and barley genomes, respectively. The results also indicate that most (72%) of the single-copy sequences in barley are also single copy in rice, suggesting that the large barley genome arose by unequal crossing over and amplification of repetitive DNA sequences and not by the duplication of single-copy sequences. Combining these results with those previously reported for comparative analyses of rice and wheat identified nine putatively syntenous chromosomes among barley, wheat and rice. The high degree of gene-order conservation as detected by comparative mapping has astonishing implications for interpreting genetic information among species and for elucidating chromosome evolution and speciation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050161
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  • 5
    Digitale Medien
    Digitale Medien
    Analysis of the barley and rice genomes by comparative RFLP linkage mapping (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 541-551 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Synteny ; Orthologous evolution ; Genetic maps ; Triticeae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Comparative genetic mapping of rice and barley, both major crop species with extensive genetic resources, offers the possibility of uniting two well-established and characterized genetic systems. In the present study, we screened 229 molecular markers and utilized 110 polymorphic orthologous loci to construct comparative maps of the rice and barley genomes. While extensive chromosomal rearrangements, including inversions and intrachromosomal translocations, differentiate the rice and barley genomes, several syntenous chromosomes are evident. Indeed, several chromosomes and chromosome arms appear to share nearly identical gene content and gene order. Seventeen regions of conserved organization were detected, spanning 287 cM (24%) and 321 cM (31%) of the rice and barley genomes, respectively. The results also indicate that most (72%) of the single-copy sequences in barley are also single copy in rice, suggesting that the large barley genome arose by unequal crossing over and amplification of repetitive DNA sequences and not by the duplication of single-copy sequences. Combining these results with those previously reported for comparative analyses of rice and wheat identified nine putatively syntenous chromosomes among barley, wheat and rice. The high degree of gene-order conservation as detected by comparative mapping has astonishing implications for interpreting genetic information among species and for elucidating chromosome evolution and speciation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00224556
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  • 6
    Digitale Medien
    Digitale Medien
    Piecewise deterministic Markov process model for flexible manufacturing systems with preventive maintenance (1994)
    Springer
    Journal of optimization theory and applications 81 (1994), S. 259-275 
    Details
    ISSN: 1573-2878
    Schlagwort(e): Flexible manufacturing systems ; controlled piecewise deterministic Markov process ; maintenance and production planning
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract In this paper, we consider a maintenance and production model of a flexible manufacturing system. The maintenance activity involves lubrication, routine adjustments, etc., which reduce the machine failure rates and therefore reduce the aging of the machines. The objective of the problem is to choose the rate of maintenance and the rate of production that minimize the overall costs of inventory/shortage, production, and maintenance. It is shown that the value function is locally Lipschitz. Then, the existence of the optimal control policy is shown, and necessary and sufficient conditions for optimality are obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02191664
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  • 7
    Digitale Medien
    Digitale Medien
    Periodic maintenance and repair rate control in stochastic manufacturing systems (1996)
    Springer
    Journal of optimization theory and applications 91 (1996), S. 347-361 
    Details
    ISSN: 1573-2878
    Schlagwort(e): Flexible manufacturing systems ; controlled Markov processes ; production planning ; repair rate control ; maintenance scheduling ; Hamilton-Jacobi-Bellman equation ; viscosity solution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract In this paper, we consider a periodic preventive maintenance, repair, and production model of a flexible manufacturing system with failure-prone machines, where the control variables are the repair rate and production rate. We use periodic preventive maintenance to reduce the machine failure rates and improve the productivity of the system. One of the distinct features of the model is that the repair rate is adjustable. Our objective is to choose a control process that minimizes the total cost of inventory/shortage, production, repair, and maintenance. Under suitable conditions, we show that the value function is locally Lipschitz and satisfies an Hamilton-Jacobi-Bellman equation. A sufficient condition for optimal control is obtained. Since analytic solutions are rarely available, we design an algorithm to approximate the optimal control problem. To demonstrate the performance of the numerical method, an example is presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02190100
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  • 8
    Digitale Medien
    Digitale Medien
    Minimax production planning in failure-prone manufacturing systems (1995)
    Springer
    Journal of optimization theory and applications 87 (1995), S. 269-286 
    Details
    ISSN: 1573-2878
    Schlagwort(e): Flexible manufacturing systems ; minimax production planning ; Hamilton-Jacobi-Isaacs equation ; viscosity solutions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract In this paper, we consider a minimax production planning model of a flexible manufacturing system with machines that are subject to random breakdown and repair. The objective is to choose the rate of production that minimizes the related minimax cost of production and inventory/shortage. The value function is shown to be the unique viscosity solution to the associated Hamilton-Jacobi-Isaacs equation. Under certain conditions, it is shown that the value function is continuously differentiable. A verification theorem is given to provide a sufficient condition for optimal control. Finally, two examples are solved explicitly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02192564
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