An Aspect-Oriented Framework for Weaving Domain-Specific Concerns into Component-Based Systems

International audienceSoftware components are used in various application domains, and many component models and frameworks have been proposed to fulfill domain-specific requirements. The general trend followed by these approaches is to provide ad-hoc models and tools for capturing these requirements and for implementing their support within dedicated runtime platforms, limited to features of the targeted domain. The challenge is then to propose more flexible solutions, where components reuse is domain agnostic. In this article, we present a framework supporting compositional construction and development of applications that must meet various extra-functional/domain-specific requirements. The key points of our contribution are: i) We target development of component-oriented applications where extra-functional requirements are expressed as annotations on the units of composition in the application's architecture. ii) These annotations are implemented as open and extensible component-based containers, achieving full separation of functional and extra-functional concerns. iii) Finally, the full machinery is implemented using the Aspect-Oriented Programming paradigm. We validate our approach with two case studies: the first is related to real-time and embedded applications, while the second refers to the distributed context-aware middleware domain

A system approach to aircraft optimization

Mutual couplings among the mathematical models of physical phenomena and parts of a system such as an aircraft complicate the design process because each contemplated design change may have a far reaching consequence throughout the system. Techniques are outlined for computing these influences as system design derivatives useful for both judgemental and formal optimization purposes. The techniques facilitate decomposition of the design process into smaller, more manageable tasks and they form a methodology that can easily fit into existing engineering organizations and incorporate their design tools

EVALUATION OF INTERCEPTOR DESIGN TO REDUCE DRAG ON PLANING HULL

A planing hull is a high-speed craft with relatively complex hydrodynamic characteristics. An increase in speed can induce a significant change in trim angle with an increment in ship drag. One solution to reduce ship resistance is to use an interceptor. This research aimed to analyze the hydrodynamics of a planing hull vessel by applying an interceptor. The fundamental aspects reviewed included the analysis of drag, trim, heave, and lift force. The interceptor would be investigated on the basis of its integrated position at its height. This research also used the computational fluid dynamic (CFD) method in calm water conditions. All simulations were conducted with the same mesh structure, which allowed the performance evaluation of the interceptor in calculating turbulent air–water flow around the ship. Numerical calculations used the Reynolds-averaged Navier–Stokes (RANS) equation with the k–ε turbulence model to predict the turbulent flow. The vertical motion of the ship was modeled using dynamic fluid–body interaction (DFBI) in the fluid domain through an overset mesh technique. The numerical approach was compared with the experimental test results of Park et al. to ensure the accuracy of the test results. The interceptor was designed at the transition phase, which showed the highest trim angle followed by high drag. The interceptor would experience negative trim at high speeds; thus, it was not recommended. The research results indicated that the most effective use of the interceptor was at Froude number 0.87 close to the chine position with a height of 100%. This interceptor could reduce a maximum of 57% drag, 17% heave, 8.48% trim, and 0.12% lift force. The interceptor could increase excessive drag and trim at Froude numbers over 1.16. The interceptor proved to be remarkably useful in trim control and ship drag reduction, but selecting the wrong dimensions and positions of the interceptor could endanger the ship. This simulation was performed on Aragon-2; thus, the interceptor performance may possibly change if a different hull geometry is used

THE PEN, THE SHIELD, OR THE SWORD? HOW THE UNITED STATES WINS THE HYPERSONIC ARMS RACE

In the past few years, China and Russia have developed offensive hypersonic missile capabilities that the United States currently can neither match nor successfully defend against. Such weapons are nuclear capable, have an unpredictable flight path, and significantly reduce reaction times for decision makers. This thesis analyzes the impact hypersonic missiles have on strategy and military combat systems to determine how the United States can best respond to China and Russia acquiring hypersonic weapons. It explores three main options: arms control negotiations, advancing the U.S. missile defense system, or the United States acquiring its own hypersonic weapons. The pros and cons of each option are weighed to determine the quickest, most affordable, and most effective approach to the hypersonic arms race.This thesis concludes that the United States should control only what it is capable of controlling: practicing transparency and confidence-building measures to set the international standard for conduct with hypersonic weapons, continuing to develop its missile defense system to keep pace with emerging threats, and acquiring hypersonic missiles to allow it the ability to operate forward-deployed forces without impediment is the best response to China and Russia.Lieutenant, United States NavyApproved for public release. Distribution is unlimited