Artigo Revisado por pares

Computer time and memory requirements for DP and DDDP in water resource systems analysis

1975; Wiley; Volume: 11; Issue: 5 Linguagem: Inglês

10.1029/wr011i005p00621

ISSN

1944-7973

Autores

Ven Te Chow, David R. Maidment, George W. Tauxe,

Tópico(s)

Advanced Optimization Algorithms Research

Resumo

The computer time required for a water resource optimization problem by dynamic programing (DP) or discrete differential dynamic programing (DDDP) may be considered as the sum of the compiling time for programing language translation, the initiating time for the program, and the execution time T E . The execution time is the dominant component of the total computer time and may be formulated as T E = T a MN П i=1 S Q i П j=1 D P j , in which T a is the time for one unit operation, M is the number of iterations involved in optimization, N is the number of stages, and Q i and P j are the number of feasible values that state variable i ( i = 1, 2, …, S) and decision variable j ( j = 1,2,…, D ), respectively, can take in each iteration or in the optimizational procedure. The value of T a depends on nature of problem, type of computer, method of coding, kind of compiler, and other factors. The computer memory required for this optimization problem may be considered as the sum of the machine memory which is relatively constant, the code memory which increases slowly with the problem size, and the data memory which increases rapidly with the problem size. The data memory consists of the basic data memory, the performance data memory P = 2 П i=1 s Q i , and the optimal decision data memory T = ND П i=1 s Q i . The cost trade offs involved in replacing core memory by slow‐speed memory (disks or tapes) are investigated. The computers used in the analysis include: IBM 360/50, IBM 360/75, IBM 360/91 and Burroughs B‐6700. The problems verifying the formulas include operations of single‐and multiple‐purpose reservoir networks and optimal design of storm sewer systems and aqueducts.

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