Multi-node Model Research Articles

Numerical simulation of fluid-structure interaction in the opening process of conical parachute

AbstractAccording to multi-node model, the dynamics equations of conical parachute system for simulating shape deformation process of the flexible canopy in the opening process were established. With the combination of dynamics equations code and computational fluid dynamics (CFD) software, the fluid-structure interaction investigation of the conical parachute was carried out. Also the change of parachute shape and flow field, inflation time, the rate of descent, the distance of descent, and other relevant data were achieved. This paper has focused on analysing vortex structure of the flow field in the opening process of conical parachute, and laid the foundation for studying mechanics mechanism of flow field variation of conical parachute in future.

Single-sector thermophysiological human simulator

Thermal sweating manikins are used to analyse the heat and mass transfer phenomena in the skin–clothing–environment system. However, the limiting factor of present thermal manikins is their inability to simulate adequately the human thermal behaviour, which has a significant effect on the clothing microenvironment. A mathematical model of the human physiology was, therefore, incorporated into the system control to simulate human thermoregulatory responses and the perception of thermal comfort over a wide range of environmental and personal conditions. Thereby, the computer model provides the physiological intelligence, while the hardware is used to measure the required calorimetric states relevant to the human heat exchange with the environment.This paper describes the development of a single-sector thermophysiological human simulator, which consists of a sweating heated cylinder ‘Torso’ coupled with the iesd-Fiala multi-node model of human physiology and thermal comfort. Validation tests conducted for steady-state and, to some extent, transient conditions ranging from cold to hot revealed good agreement with the corresponding experimental results obtained for semi-nude subjects. The new coupled system enables overall physiological and comfort responses, health risk and survival conditions to be predicted for adult humans for various scenarios.

An integrated model for simulating interactive thermal processes in human–clothing system

Stolwijk's multi-node model is modified by considering the sweat accumulation on the skin surface and is applied to simulate the human physiological regulatory response. This human model is interfaced with a coupled heat and moisture model of clothing materials that takes into consideration the adsorption of water vapor in the fibers. Furthermore, a multi-layer clothing system is developed and integrated with the human model. The result agrees well with the published experimental data.

Mathematical modeling of thermal physiological responses of clothed infants

The objective of this study is to develop a mathematical model for simulating the thermal physiological responses of clothed infants. By modifying and integrating Gagge's two-node model and Stolwijk's multi-node model, and coupled with the model of dynamic couple heat and moisture transfer in functional clothing, a new seven-node thermoregulation model for closed infants was developed. A series of preliminary numerical test were carried out for naked and clothed infant. The prediction of the new model was compared with the published data, the comparison results demonstrate that the model has good potential predictability.

The preparation and testing of spectrally selective paints on different substrates for solar absorbers

In this paper the preparation and testing of spectrally selective paint coatings for absorbers in flat-plate solar collectors are shown. This represents the most inexpensive way of preparing such an absorber. Basic properties of coatings prepared on aluminum, copper and stainless steel substrates are described together with the stability of the painted substrate. To calculate the performance of the solar collector with a painted absorber, a dynamic multi-node model was applied. It considers the main components and heat transfer fluxes of a flat-plate solar collector.

A Partitioning-Independent Paradigm for Nested Data Parallelism

A generalization of the data parallel model has been proposed by Blelloch which permits the nesting of data parallel operators to specify parallel computation across nested and irregular data structures. In this paper we consider the costs of supporting the general model of nested data parallelism, analyzing the requirements such a model places upon an underlying model of execution. We propose a new multi-node execution model which meets the needs of the paradigm and is additionally generic in the partitioning of data aggregates within the system. The basis for our execution model is an abstract machine based upon elementary notions of nodal multi-threading. We demonstrate the utility of our proposal by providing a full definition for a simple nestable one-dimensional data parallel operator. We discuss the applicability of our design to existing multi-processor machines, illustrating performance statistics gathered from a prototype system we have constructed on the Thinking Machines CM-5.

Dynamic solar collector performance testing

Abstract A dynamic solar collector model in conjunction with a dynamic parameter identification and performance prediction method is presented. It promises to make possible solar collector (loop) testing under instationary outdoor meteorological conditions, variable inlet temperature and variable volume flow rate. Measurements for three test sequences were made outdoors under instationary conditions on a 6 m2 flat plate collector array with double glazing. A multi-node model with three parameters (effective area, effective loss coefficient andthermal capacity) is used. Collector parameters are determined for one sequence and the collector performance is then predicted for the remaining two sequences using the same model with the already determined parameters. The error of predicting the temperature difference across the collector, averaged over a sequence, is found to lie at or below 0.2 K. A computer program package providing the parameter identification and performance prediction algorithms as well as the collector model is available.

Application of Noise Analysis Technique for Monitoring the Moderator Temperature Coefficient of Reactivity in Pressurized Water Reactors

A new technique, based on the noise analysis of neutron detector and core-exit coolant temperature signals, is developed for monitoring the moderator temperature coefficient of reactivity in pressurized water reactors (PWRs). A detailed multinodal model is developed and evaluated for the reactor core subsystem of the loss-of-fluid test (LOFT) reactor. This model is used to study the effect of changing the sign of the moderator temperature coefficient of reactivity on the low-frequency phase angle relationship between the neutron detector and the core-exit temperature noise signals. Results show that the phase angle near zero frequency approaches - 180 deg for negative coefficients and 0 deg for positive coefficients when the perturbation source for the noise signals is core coolant flow, inlet coolant temperature, or random heat transfer.

Importance of skin temperature in the regulation of sweating.

Human sweating regulation at rest, evaluating thermal inputs effects on thermoregulatory center and internal hypothalamic and skin temperatures