TY - JOUR AU - Betz, Stefan ID - 2604 JF - Der Betriebswirt TI - Standortwahl als Entscheidungsproblem des Logistikcontrollings VL - 50 ER - TY - JOUR AB - In this paper, we consider a model for precipitation experiments based on the population balance equation. The study revealed a high sensitivity of the system with respect to the modeling of intrinsic parameters, motivating a comprehensive validation of the estimates. In the forward simulation the impact of the influencing parameters including surface energy, nucleus size and distribution is investigated. Subsequently we construct a simplified model of the precipitation process in such a way that it is orbitally flat in terms of control theory, which enables the inverse calculation of the parameters. The numerical results of the inverse simulation for the interfacial energy have been compared to a physical model. The possibility of solving the inverse problem provides a promising way of estimating hardly measurable quantities for more complex molecules. AU - Vassilev, Vassil AU - Gröschel, Michael AU - Schmid, Hans-Joachim AU - Peukert, Wolfgang AU - Leugering, Günter ID - 26137 IS - 6 JF - Chemical Engineering Science SN - 0009-2509 TI - Interfacial energy estimation in a precipitation reaction using the flatness based control of the moment trajectories VL - 65 ER - TY - JOUR AB - In this work, a new model for the simulation of nanostructured aggregates by simultaneous coagulation, sintering and surface growth is presented. Coagulation is treated as cluster–cluster agglomeration along the line connecting the center of mass of both agglomerates and is implemented using a Monte Carlo algorithm. Sintering is modeled as successive overlapping of spheres which cause reduction in the surface area based on a rate law for surface reduction. Surface growth is modeled as an increase in primary particle diameter, e.g. as a result of surface reactions. The evolved aggregates are analyzed by calculating their fractal dimension, radius of gyration, mobility diameter and mobility shape factor. It is found that the aggregates structure tends to be more compact when introducing the surface growth in shorter time comparing to the coagulation-sintering step only. Fractal dimension and the mobility shape factor of the resulting aggregates are correlated to an effective dimensionless time that combines the characteristic times of these three fundamental mechanisms. It is shown that the mobility diameter in the free molecular regime is not proportional to the radius of gyration. A power law relation that correlates the aggregates projected area and the equivalent number of primary particles is found to be in a very good agreement with estimates published in literature. AU - Al Zaitone, Belal AU - Schmid, Hans-Joachim AU - Peukert, Wolfgang ID - 26138 IS - 11 JF - Journal of Aerosol Science SN - 0021-8502 TI - Simulation of structure and mobility of aggregates formed by simultaneous coagulation, sintering and surface growth VL - 40 ER - TY - JOUR AB - The study presents first experimental results of the transfer of magnetite nanoparticles from an aqueous to a second non-miscible non-aqueous liquid phase. The transfer is based on the adsorption of macromolecular surfactants onto the particle surface at the liquid–liquid interface. For a successful direct phase transfer, it is essential to have cations, like ammonium ions, present in the aqueous phase as well as a threshold concentration of surfactant in the organic liquid phase. While penetrating the liquid–liquid interface, the particles are covered with the surfactant and therefore a partial de-agglomeration is initiated. Based on literature and experimental data a mechanism of surfactant adsorption is proposed. The competing adsorption of the surfactant molecules at the liquid–liquid interface leads to the formation of emulsions and therefore to a hindrance for particles passing the interface. Nevertheless a high efficiency of 100% yield can be reached using optimized process parameters for the phase transfer process. AU - Machunsky, Stefanie AU - Grimm, Philipp AU - Schmid, Hans-Joachim AU - Peuker, Urs A. ID - 26139 IS - 1-3 JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects SN - 0927-7757 TI - Liquid–liquid phase transfer of magnetite nanoparticles VL - 348 ER - TY - JOUR AB - The viscous-flow sintering of different agglomerate particle morphologies is studied by three-dimensional computer simulations based on the concept of fractional volume of fluid. For a fundamental understanding of particle sintering characteristics, the neck growth kinetics in agglomerate chains and in doublets consisting of differently sized primary particles is investigated. Results show that different sintering contacts in agglomerates even during the first stages are not completely independent from each other, even though differences are small. The neck growth kinetics of differently sized primary particles is determined by the smaller one up to a size difference by a factor of approximately 2, whereas for larger size differences, the kinetics becomes faster. In particular, the agglomerate sintering kinetics is investigated for particle chains of different lengths and for different particle morphologies each having ten primary particles and nine initial sintering contacts. For agglomerate chains, the kinetics approximately can be normalized by using the radius of the fully coalesced sphere. In general, different agglomerate morphologies show equal kinetics during the first sintering stages, whereas during advanced stages, compact morphologies show significantly faster sintering progress than more open morphologies. Hence, the overall kinetics cannot be described by simply using constant morphology correction factors such as fractal dimension or mean coordination number which are used in common sintering models. However, for the first stages of viscous-flow agglomerate sintering, which are the most important for many particle processes, a sintering equation is presented. Although we use agglomerates consisting of spherical primary particles, our methodology can be applied to other aggregate geometries as well. AU - Kirchhof, M. J. AU - Schmid, Hans-Joachim AU - Peukert, W. ID - 26140 IS - 2 JF - Physical Review E SN - 1539-3755 TI - Three-dimensional simulation of viscous-flow agglomerate sintering VL - 80 ER - TY - THES AU - Huber, Daniel ID - 26183 TI - Geregelte Vereinfachung hierarchischer Partitionen von Modellen in der Materialflusssimulation VL - 277 ER - TY - JOUR AU - Sperling, Jan AU - Vogel, W. ID - 26360 JF - Physical Review A SN - 1050-2947 TI - Verifying continuous-variable entanglement in finite spaces ER - TY - JOUR AU - Sperling, Jan AU - Vogel, W. ID - 26361 JF - Physical Review A SN - 1050-2947 TI - Representation of entanglement by negative quasiprobabilities ER - TY - JOUR AU - Sperling, Jan AU - Vogel, W. ID - 26362 JF - Physical Review A SN - 1050-2947 TI - Necessary and sufficient conditions for bipartite entanglement ER - TY - JOUR AU - Dzienziol, J. AU - Kundisch, Dennis ID - 2649 IS - 4 JF - Kredit und Kapital TI - Optimale Darlehensbündel in der privaten Immobilienfinanzierung VL - 42 ER -