Transportvorgänge in Festbetten Geschichte,Stand und Perspektiven der Forschung

Transport phenomena in packed beds: History, state of the art, and research outlook. This review tries to give an impression about the history, the state of the art, and the research outlook for heat, mass, and momentum transfer in packed beds. The methodology of model development and experimental analysis is thoroughly discussed on the basis of examples; several postulates are introduced for its codification. This methodology is not restricted to packed beds but can also be applied to other disperse systems with or without chemical reaction. Formulas and guidelines for calculations are not given; handbooks and other related papers are quoted for this purpose.     

A note on weighted distributed match-making

In many distributed computing environments, processes are concurrently executed by nodes in a store-and-forward network. Distributed control issues as diverse as name-server, mutual exclusion, and replicated data management, involve making matches between processes. The generic paradigm is a formal problem called “distributed match-making.” We define multidimensional and weighted versions, and the relations between the two, and develop a very general method to prove lower bounds on the complexity as a tradeoff between number of messages and “distributedness.” The resulting lower bounds are tight in all cases we have examined. We present a success-stop version of distributed match-making that is analysed in terms of a weight distribution that in all cases results in approximately halving the (expected) number of messages required in the corresponding strategy that does not use these weights. The second author did part of this work at the Laboratory for Computer Science, M.I.T., Cambridge, MA. He was supported in part by the Office of Naval Research under Contract N00014-85-K-0168, by the Office of Army Research under Contract DAAG29-84-K-0058, by the National Science Foundation under Grant DCR-83-02391, and by the Defence Advanced Research Projects Agency (DARPA) under Contract N00014-83-K-0125. A preliminary version of this paper appeared inProc. VLSI Algorithms and Architectures, 3rd Aegean Workshop on Computing (AWOC 88), Lecture Notes in Computer Science, vol. 319, Springer-Verlag, Berlin, 1988, pp. 361–368.     

Hydrological balance and application of the MedWater Model on Naxos Island

The MedWater model was used to determine both the present and future water balances of the largest water basin on Naxos Island, Greece, comparing water resource availability with water demand while also testing assumptions related to the regional hydrological context and different future scenarios. The model indicated that: the required quantities of water for both irrigation and drinking needs reach their annual maximum values during the summer season; the annual water balance shows a general surplus, but not on a monthly basis; the available quantities of water are not enough to cover irrigation demands during the annual dry period; available water resources maximize in March and are generally under-exploited; and the required volumes of water for both irrigation and direct human consumption will increase in the future.     

Design study of printer nozzle spray dryer by computational fluid dynamics modeling

Abstract

Milk powder production is one of the most energy-consuming processes in the dairy industry. To reduce production costs and increase spray dryer efficiency, the EU sponsored an international project named ENTHALPY. One of the results of the project was the development of mathematical models and computational fluid dynamics simulation methodology for the milk spray-drying process. This article introduces the methodology of CFD model development and presents simulation results as the basis for further drying tower design optimization. The CFD simulations were performed for a new design of monodisperse multistream atomizer. As a result of the CFD simulation, sets of parameters such as drying efficiency, protein thermal degradation, collision frequency, and wall deposition were obtained.     

Location-Oblivious Distributed Unit Disk Graph Coloring

We present the first location-oblivious distributed unit disk graph coloring algorithm having a provable performance ratio of three (i.e. the number of colors used by the algorithm is at most three times the chromatic number of the graph). This is an improvement over the standard sequential coloring algorithm that has a worst case lower bound on its performance ratio of 4−3/k (for any k>2, where k is the chromatic number of the unit disk graph achieving the lower bound) (Tsai et al., in Inf. Process. Lett. 84(4):195–199, 2002). We present a slightly better worst case lower bound on the performance ratio of the sequential coloring algorithm for unit disk graphs with chromatic number 4. Using simulation, we compare our algorithm with other existing unit disk graph coloring algorithms.     

Piso sto Chorio … I Apantisi stin Krisi einai i Agrotiki Paragogi[Back to the Village … The Answer to the Crisis is Agricultural Production]

In this study, groups of batch experiments were designed to identify the characteristics of alum sludge for arsenic (As) adsorption. Air-dried alum sludge (moisture content 13.9%) collected from a water treatment works in Xi’an, China, was subjected to artificial As-rich wastewater adsorption tests using As₂O₃ as a model As source. Adsorption behaviours were investigated and the results have shown that the Langmuir adsorption isotherm well fits the experimental data (R² = 0.94957–0.99365). The maximum adsorption capacities range from 0.61 to 0.96 mg-As/g when the pH of the As solution was varied from 9.0 to 4.0. The prospects in China for the outcome of this study are discussed. This promising low-cost technique can eradicate As contamination in China.