New method of reliability analysis and calculation on grey maintainable system
A new model for reliability analysis and calculation of the grey maintainable system is put forward based on the grey theory to tackle the problem of lacking information for practical application. The feasibility of the proposed method is confirmed by a numerical example. The feature of this new method is that it can analyze system reliability dynamically and master its development law because it does not depend on the distribution parameters of system. Hence, it can be used to preview the reliability of system.
On air defense communications network connectivity
The authors address the issue of communication network survivability and provide a quantitative measure of the time-varying connectivity of space and ground multimedia networks operating in stressed environments. This measure allows comparison of very different network architectures in terms of connectivity. A generic SBR (Space-Based Radar) constellation was selected for study of the communications connectivity. The SBR, consisting of constellations of low Earth orbit satellites, will require dynamic, robust communication protocols and networks to support the various missions for the Air Force, Navy, and other military organizations. The authors present a methodology that can be used to define connectivity requirements once the threat and system parameters are better defined.<<ETX>>
Ocean thermal energy conversion: The promise of a clean future
Due to the world's heavy dependence on fossil fuels for electricity, pollution and global warming is on the rise. However, numerous countries are still relying on diesel generators as their main source of energy. There is a lack of practical alternative energy source that can meet the global energy demand without posing any threat to the natural environment. Ocean Thermal Energy Conversion (OTEC) is a concept that has the potential to address this growing issue. It is basically a mechanism that exploits the temperature difference between warm surface seawater and cold deep ocean water, to produce electricity. Although OTEC has a low energy density, the thermal energy in the ocean is vastly abundant. OTEC development has been dormant for a long time since it was first proposed in 1881. However, it has now regained recognition worldwide as a realistic solution to our world energy issue. Instead of having a great potential for power generation, it also carries the ability to produce high value products from the large volume of Deep Sea Water (DSW) that can be released as byproducts of OTEC plant operation. These products can hold a very profitable place in industries such as pharmaceutical, food, cosmetics and mineral water production. Further research on ocean current and DSW properties can someday lead to the commercial used of OTEC. This paper is a review of the basic concept, present status and future prospects of OTEC around the world.