Combination Of Structural Parameters Research Articles

Synthesizing optimal design configurations for a brayton cycle power plant

This paper demonstrates the use of the simulated annealing method for the analysis of design configurations for a Brayton cycle power plant. This application centers around a sequential modular chemical process simulator, the Space Nuclear Auxiliary Power System (SNAPS), designed to simulate the operation of power plants with different energy conversion techniques, to find optimal characteristics constrained by feasibility limitations, and to design the plant for maximum flexibility and reliability. The modular nature of SNAPS allows for the analysis of numerous configurations of nuclear power plants. Since the solution space is characterized by a large number of design and structural parameter combinations, it demonstrates the successful applicability of simulated annealing as a synthesis tool for nuclear power plant design problems. Simulated annealing is found to perform very well in the face of a large number of discontinuities in the solution space.

Scheduling Trees in Parallel/Pipelined Processing Environments

Scheduling task trees to be executed in parallel and/or pipelined processing systems are examined under individual situations. Processor structural requirements at task nodes are also included in the model of consideration. While simple techniques can serve as heuristics, counterexamples are constructed in some crucial cases. Simple optimal algorithms are presented in two important cases: 1) unistructure, multipipe, uniform latency, and flush time; and 2) vector loops. Finally, the complexity of the remaining cases is scrutinized with different structural parameter combinations.

Bonded and nonbonded interactions in saturated alcohols, ethers, thiols, thioethers, and amines

The enthalpies of formation (ΔH°f) of alcohols, ethers, thiols, thioethers, and amines are expressed as linear combinations of structure parameters. The linear coefficients are determined from experimental ΔH°f using the least squares criterion. For these calculations eight structure parameters are used for thiols and thioethers, nine for amines, and ten for alcohols and ethers. The mean and root-mean-square deviations between calculated and experimental values are, respectively, ±0.17 and ±0.25 kcal mole−1 for 30 gaseous alcohols and ethers, ±0.17 and ±0.25 kcal mole−1 for 32 liquid and ±0.19 and ±0.27 kcal mole−1 for 31 gaseous thiols and thioethers, and ±0.12 and ±0.23 kcal mole−1 for 18 liquid amines. Liquid phase data of 28 alcohols and ethers and gas phase data of 13 amines are also treated with this model but the results are not satisfactory. The linear coefficients may be used for predicting unknown ΔH°f and for estimating enthalpy differences between certain conformers. Those corresponding to the various 1,4 nonbonded interactions indicate that the gauche CCCC, CCOC, CCNC, CCOH, and CCNH interactions are repulsive, but the gauche CCCO and CCCN, interactions are attractive. The only 1,5 interactions considered are the gauche–gauche prime CCOCC and CCSCC interactions and they are found highly repulsive. The relative stability of conformers predicted on the basis of these nonbonded interactions agrees quite well with results from experiments and molecular orbital calculations.

Influence of Line Motion on Waterhammer Pressures

The large pressure increases following rapid valve closures in liquid flow pipe systems produce large forces which must be resisted by the system structure. These forces invariably produce motion of the pipe line. The motion which is usually of small amplitude is generally ignored in waterhammer analysis. It is shown, however, that the motion may produce pressures that differ significantly from those predicted using rigidly supported pipelines. Initial pressure surges with magnitudes greater than 20% above the commonly used maximum for instantaneous valve closure may result under certain combinations of structural parameters and closing conditions and subsequent surges can be much greater than the initial surge. Under other conditions, it is shown that the pressure buildup is significantly retarded and the line motion can be utilized to control the waterhammer pressures. The line motion associated with the waterhammer surge can also produce characteristics such as pressure overshoot and jagged portions of the pressure trace which have often been observed experimentally.