Valve, normally closed, titanium Pyronetics model 1426

Performance tests of the explosive actuated, normally closed titanium valve 1426, are outlined. The valves are used to control hydrazine flow in a monopropellant thruster. Data cover pressure tests, internal and external leakage tests, flow control tests, and actuator tests. No failures were noted in any of the tests

Exponential decay properties of a mathematical model for a certain fluid-structure interaction

In this work, we derive a result of exponential stability for a coupled system of partial differential equations (PDEs) which governs a certain fluid-structure interaction. In particular, a three-dimensional Stokes flow interacts across a boundary interface with a two-dimensional mechanical plate equation. In the case that the PDE plate component is rotational inertia-free, one will have that solutions of this fluid-structure PDE system exhibit an exponential rate of decay. By way of proving this decay, an estimate is obtained for the resolvent of the associated semigroup generator, an estimate which is uniform for frequency domain values along the imaginary axis. Subsequently, we proceed to discuss relevant point control and boundary control scenarios for this fluid-structure PDE model, with an ultimate view to optimal control studies on both finite and infinite horizon. (Because of said exponential stability result, optimal control of the PDE on time interval $(0,\infty)$ becomes a reasonable problem for contemplation.)Comment: 15 pages, 1 figure; submitte

Commercially-and-socially-oriented postal services

The main goal of this paper is show how postal communication service, which has been strengthened with the technology development in the last century, is nowadays commercially-and-socially-oriented very important for human life. Furthermore, I will prove how postal service becomes overwhelming for some not communicated, far and isolated geographic areas in developing countries, to get in touch with people and businesses from around the world. Over one hundred of Postal Operators were interviewed in Peru between 2004 and 2006, around 25% of total, which said that distance and security are not longer considered as a challenge for postal services thanks to new Information and Communication Technologies (ICT) and Internet; which in turn has facilitated (i) social communication, (ii) financial services, (iii) e-commerce and (iv) international business, bolstered by postal services. This last issue can be proved with high correlation statistics between the international postal (and courier) shipments and the exportation of non traditional goods, as well as importation of goods in Peru; moreover, some international remittances from around the world are making through the postal transferences. Consequently, Peruvian authorities, especially from the Ministry of Transport and Communications, must consider the importance of postal and/or courier services in the elaboration of public policies to pursuit the socioeconomic development.Postal services; financial postal; international business; communication; e-commerce;