Help Of Invariants Research Articles

Classification of passive location invariants and their use

In the context of all kinds of passive location systems, we consider different types of invariants taking into account the temporal, spatial, and spatiotemporal symmetries, which can be used to solve specific problems of target tracking. We classify these invariants, give ways of their finding based on models of the motion of observed targets, and describe the structures and geometries of the given passive location system. We consider important applied problems that can be solved with the help of invariants.

Defining business process flexibility with the help of invariants

AbstractEnterprise survival is about maintaining an identity that is separate from other enterprises. We define flexibility as the ability to change without losing identity. The identity of an enterprise can be analyzed as a set of norms and beliefs about these norms held by its stakeholders, such as customers, employees, suppliers, and investors. Business processes and their support systems maintain invariants that are the result of compromises between the often conflicting norms and beliefs of these stakeholders. We formalize these invariants as values in a state space. Identifying a minimum set of invariants provides a basis for defining flexible processes and support systems. We illustrate the use of this framework with production business process support (BPS) systems. Copyright © 2006 John Wiley & Sons, Ltd.

Mathematical models of high temperature flow in gas ducts of rocket engines

Results are given on certain dynamic properties of a high temperature and pressure gas flow. The investigation concerns the effect of sonic processes on the transfer of external signals by the flow and of the gas nonidealities on the properties of a linear and a nonlinear mathematical model of the jet nozzle. The investigation was conducted by the method of small parameters for differential equations of the dynamics of the gas flow, with the help of invariants of these equations, and estimates of solutions with arbitrary signals of a specific class. The results lead to estimates of errors due to usual simplifications of gas flow models such as linearization of jet nozzle equations and neglect of sonic processes. The errors of the latter kind are shown to depend on the Mach number and smoothness of signals. Accurate and approximate models of nozzle flow are obtained useful for controllability analysis of rocket engines. Some computation examples are given.