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  • 1995-1999  (3)
  • Chemical Engineering  (2)
  • 68M20  (1)
  • 68.55Jh
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Computing 57 (1996), S. 255-271 
    ISSN: 1436-5057
    Keywords: 90B35 ; 68M20 ; k-partitioning containing kernels ; NP-complete ; worst case analysis ; LPT-algorithm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Seik≥2 eine natürliche Zahl undG= $$\{ g_1 ,g_2 , \cdots ,g_m \} \cup \{ t_1 ,t_2 , \cdots ,t_n \} $$ eine Menge von höchstenskm nichtnegativen ganzen Zahlen. Gesucht ist eine Partition vonG= $$\{ g_1 ,g_2 , \cdots ,g_m \} \cup \{ t_1 ,t_2 , \cdots ,t_n \} $$ inm Teilmengen, die jeweils nicht mehr alsk Elemente enthalten, sodaß alleg i (Kerne genannt) unterschiedlichen Teilmengen zugeordnet werden und die maximale Summe von Zahlen in einer dieser Teilmengen möglichst klein wird. Wir zeigen zunächst, daß für jedesk≥3 dieses Problem NP-vollständig im starken Sinne ist. Als Heuristik für dieses Problem benutzen wir eine revidierte Version des bekannten LPT-Algorithmus für das Multiprozessorscheduling-Problem. Fürk=3 zeigen wir eine Worst-Case Schranke von 3/2–1/2m.
    Notes: Abstract LetG= $$\{ g_1 ,g_2 , \cdots ,g_m \} \cup \{ t_1 ,t_2 , \cdots ,t_n \} $$ be a list of items with nonnegative weights assigned andk≥2 be an integer. The objective is to find an assignment of the items to the bins such that allg i (called kernels) are assigned to different bins, such that no bin contains more thank items, and such that the maximum weight assigned to any bin becomes minimum. In this paper, we first prove that the problem is NP-complete in the strong sense for anyk≥3. As heuristic for this problem, we use a modified version of the famous LPT-algorithm for multiprocessor scheduling, and we show a worst case bound of 3/2–1/2m fork=3.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2661-2663 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1706-1714 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental studies of polymer melt flow in the filling and post-filling stages of the injection molding process were performed using the sequential injection of transparent and colored polystyrene resin. Effects of fountain flow in the filling stage, geometrical factors caused by edges and corners, as well as flow through contractions and expansions, were identified. Significant polymer melt flow which increases with increased packing pressure was observed in the post-filling process. The melt flow is more concentrated around the gate area than away from the gate. It was also found that the polymer melt flows across the gap center, resulting in partial annihilation of the weld line. Simulations based on the control-volume/finite-element method employed within each gapwise layer combined with the dual-filling-parameter technique were developed to trace the advancements in melt fronts for both skin and core materials. Numerical simulations show reasonable consistency with experimental results in both skin and core material distribution. If the edge effect is taken into account using a shape factor as a geometrical correction, the simulation accuracy is further improved.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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