Performance Prediction Methodology Research Articles

PERFORMANCE PREDICTION OF PARALLEL SELF CONSISTENT FIELD COMPUTATION

This paper presents a methodology for performance prediction of parallel algorithms and illustrates its use on a large scale computational chemistry application. The performance prediction uses a component time characterization technique which splits up the sequential code into computational components and measures the time for each of them. The parallel algorithm is built from these components by adding communication routines. A “Processor Activity Graph” (PAG) providing a graphical representation of the parallel algorithm runtime behaviour is used for predicting the execution time. For a case study a Self Consistent Field (SCF) computation has been selected which forms the basis of many computational chemistry packages [4, 5]. The performance model of SCF computation has been built and the prediction have been compared with the results of measurements. The measurements have been provided on a mesh connected distributed memory parallel computer (128 T800 Parsytec SuperCluster). The prediction error is less than 10%. Performance optimisation of the application has been achieved by reducing the communication overhead and changing the data representation.

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Advanced ceramics and ceramic matrix composites are being considered for extended service in high temperature environments. Designers and users therefore need to be able to characterize accurately the creep performance of such materials under realistic, long‐term, multi‐axial tensile loading. However, direct measurement of the required long‐term properties is difficult, expensive and time consuming. ERA Technology therefore plans to launch a multi‐client research programme aimed at the development and validation of generic long‐term performance prediction methodologies.

Rapid methodology for design and performance prediction of integrated supersonic combustion ramjet engine

The design integration of a supersonic combustion ramjet engine (SCRAMJET) with an airframe dictates the mission success of transatmospheric or hypersonic cruise vehicles. Special interest must be given for the hypersonic atmospheric boost phase of the mission where most of the propulsive energy is expended. For this purpose, the operational efficiency is established by the effective specific impulse and the thrust to weight ratio of the accelerating vehicle. In order to analyze the foregoing problems, a methodology is developed, which permits a quick performance evaluation of an idealized, integrated SCRAMJET vehicle for preliminary design analysis. The capabilities of methodology are 1) designing an integrated vehicle consisting of the forebody inlet, supersonic flow combustor and afterbody expansion nozzle; 2) generating the design and off-design performance data; and 3) performing many design iterations for tradeoff studies. Samples of the design and off-design performance analysis of generic hypersonic vehicles are presented. The methodology is suitable to be programmed and executed on a personal computer.

Analytical study of swirler effects in annular propulsive nozzles

THIS paper presents an analytical performance prediction methodology for annular propulsive nozzles with swirl introduced ahead of the combustor that feeds the nozzle. The methodology is applied to investigate the effects of swirier design on nozzle performance. Four types of swirlers are investigated: free vortex, constant angle, forced vortex, and Rankine vortex swirlers. Discharge coefficients and specific impulses are presented. Contents

An analytical investigation of swirl in annular propulsive nozzles

An analytical performance prediction methodology for annular propulsive nozzles with swirl introduced in the combustor upstream of the nozzle is presented. The application of that methodology to a specific nozzle design for a free vortex swirl distribution is discussed. Discharge coefficients, specific impulses, and wall pressure distributions are presented. These numerical studies show that the discharge coefficient, thrust, and specific impulse decrease as the amount of swirl increases. This methodology will enable nozzle designers to account for the effects of swirl in nozzle design.

A Performance Prediction Methodology for Integral Collection-Storage Solar Domestic Hot Water Systems

A performance prediction methodology is developed which is applicable to most commercially available integral collection-storage passive solar domestic hot water systems. A computer model of a general ICS component was created to be compatible with the transient simulation program TRNSYS[3], and was used to develop and verify the simpler monthly performance prediction method. The method uses the system parameters from available test methods, monthly average climatic data, and load size to predict long term performance of ICS systems.

Empirical Television Sensor Performance Model

An empirical TV range performance prediction methodology is described that depends on only two TV camera merit functions. These merit functions are the MRS, or minimum resolvable signal, and Ir, the background reference current. Both can be measured. This methodology differs from other TV system performance models in that it does not require detailed knowledge of the camera design characteristics, nor does it require extensive measurement of merit functions. The described methodology removes the need to rely heavily on incomplete theoretical models and replaces them with a largely empirical method more likely to yield reliable results. The simplified approach allows many camera designs to be optimized for application requirements and evaluated without an extensive modeling effort.

An analytical and experimental investigation of annular propulsive nozzles

Abstract : The final report consists of AIAA papers. The report presents an analytical performance prediction methodology for annular propulsion nozzles with and without swirl introduced in the combustor upstream of the nozzle. Four types of swirlers were investigated: free vortex, constant angle, forced vortex and Rankine vortex swirlers. For the no-swirl case thrust efficiencies and static pressure profiles from cold flow testing of selected nozzles are summarized and compared to the predictions.... Ramjets, Supersonics.

Capture of mineral particles in a high gradient magnetic field

The particle capture characteristics of a high gradient magnetic separator (HGMS) operated with drainage have been investigated. The parameters tested are those introduced in the force balance model of capture. Also tested is matrix loading ( i.e. feed weight per unit of matrix weight). A wide range of conditions was employed, viz. magnetic susceptibility, 0.25 − 8.00 × 10 −4 emu/cm 3 Oe; particle size, 8 – 48 μm; field strength, 0 – 20 kG; flow velocity, 2 – 22 cm/sec; viscosity, 0.7 – 1.5 cP; and matrix loading, 0.17 – 2. All the parameters are shown to be important in particle capture except for viscosity, which plays a minor role. The relationship between capture and the force balance is revealed to be quite complex. A long-term objective is to develop a methodology of HGMS performance prediction for real systems. To this end an empirical model is constructed relating recovery to the tested parameters. Use of the model is illustrated by predicting separation of uni-sized synthetic hematite/silica mixtures and capture of a wide range of hematite particles.