Stress-testing of the throat of a rocket's nozzle

Test motor in which high initial pressure can be reduced suddenly provides a method of testing stress effects in the throat of a rockets nozzle. Motors operating pressure is increased to aggravate tensile stresses in a submerged throat. Opposing compression stresses are limited by control of the operating pressure

Optimizing Control of a Batch Reaction Process

The batch chemical reaction is chosen as the process model to be optimized and the rate constants are functions of pressure only, as the reactions are assumed to occur isothermally. The time optimal control problem considered here means to determine the minimum time path from the given initial compositions to desired final compositions by manipulating the process pressure. A gradient method or a steepest-ascent method is applied to determine the control variable program by using the high speed digital computer. Numerical solutions are presented for the following three cases: (1) no constraint on the operating pressure ...... open and matched terminal constraint. (2) constraint on the operating pressure ...... open terminal constraint. (3) constant operating pressure ...... open terminal constraint

Stainless steel 301 and Inconel 718 hydrogen embrittlement

Conditions and results of tensile tests of 26 Inconel 718 and four cryoformed stainless steel specimens are presented. Conclusions determine maximum safe hydrogen operating pressure for cryogenic pressure vessels and provide definitive information concerning flaw growth characteristics under the most severe temperature and pressure condition

Parametric numerical analysis of fire-induced pressure variations in a well-confined and mechanically ventilated compartment

The investigation of a fire in a well-confined and mechanically ventilated compartment is of primary importance for the nuclear industry. In normal operating conditions, a ventilation network system is set-up to ensure confinement via an appropriate pressure cascade. In the event of a fire, the subsequent pressure build-up alters the confinement level significantly and therefore changes the level of safety of the installation. The fire-induced pressure variations depend mainly on the: (1) HRR (Heat Release Rate) history of the fire, (2) heat losses to the walls, (3) leakage area, and (4) operating conditions of the fans. A numerical parametric analysis on the latter three parameters, using the Fire Dynamics Simulator (FDS 5.5.3), have shown that a change in the initial ventilation parameters (i.e. operating conditions of the fans and/or leaks), which can be sometimes difficult to determine, may lead to substantial changes in the pressure profiles. However, only a change in the thermal boundary conditions (i.e. presence or no of insulation) produces significant changes in the gas temperature

Control system for an artificial heart

Inexpensive industrial pneumatic components are combined to produce control system to drive sac-type heart-assistance blood pump with controlled pulsatile pressure that makes pump rate of flow sensitive to venous /atrial/ pressure, while stroke is centered about set operating point and pump is synchronized with natural heart

High- and low-pressure pneumotachometers measure respiration rates accurately in adverse environments

Respiration-rate transducers in the form of pneumotachometers measure respiration rates of pilots operating high performance research aircraft. In each low pressure or high pressure oxygen system a sensor is placed in series with the pilots oxygen supply line to detect gas flow accompanying respiration

Neural regulation of cardiovascular response to exercise: role of central command and peripheral afferents

During dynamic exercise, mechanisms controlling the cardiovascular apparatus operate to provide adequate oxygen to fulfill metabolic demand of exercising muscles and to guarantee metabolic end-products washout. Moreover, arterial blood pressure is regulated to maintain adequate perfusion of the vital organs without excessive pressure variations. The autonomic nervous system adjustments are characterized by a parasympathetic withdrawal and a sympathetic activation. In this review, we briefly summarize neural reflexes operating during dynamic exercise. The main focus of the present review will be on the central command, the arterial baroreflex and chemoreflex, and the exercise pressure reflex. The regulation and integration of these reflexes operating during dynamic exercise and their possible role in the pathophysiology of some cardiovascular diseases are also discusse

A physically based fluorescent lamp model for a SPICE or a simulink environment

This paper describes a method of modeling fluorescent lamps. The lamp model can be implemented in all major circuit simulation software packages, an example has been given for SPICE and Simulink. The model is based upon a simplified set of physical equations that gives the model validity over a wider range of operating conditions than current fluorescent lamp SPICE models allow for. The model can be used to model any low-pressure mercury-buffer gas fluorescent lamps by entering key lamp parameters, length, radius, cold-spot temperature, and buffer gas fill pressure. If fill pressure is not known, a default value dependent on lamp radius is used. The model shows good agreement over a wide range of operating frequencies and lamp powers