Mitre Corporation

About: Mitre Corporation is a company organization based out in Bedford, Massachusetts, United States. It is known for research contribution in the topics: Air traffic control & National Airspace System. The organization has 4884 authors who have published 6053 publications receiving 124808 citations. The organization is also known as: Mitre & MITRE.

Spatial null steering microstrip antenna array

Abstract: A spatial null steering microstrip antenna array comprising two concentric microstrip patch antenna elements An inner circular antenna is used as an auxiliary element in nulling interference received by an outer annular ring antenna disposed around the inner antenna The outer annular antenna is resonant in a higher order mode but forced to generate a right hand circularly polarized lower order (TMll) far field radiation pattern, thereby allowing co-modal phase tracking between the two antenna elements for adaptive cancellation Each antenna element is appropriately excited by symmetrically spaced probes Other applications of the antenna array include GPS multipath suppression, simultaneous satellite and terrestrial communications, and co-site interference suppression Dual frequency band applications are achieved by stacked array configurations

Encouraging Student Reflection and Articulation using a Learning Companion

Abstract: Intelligent tutoring systems (ITS) provide students with individualized instruction and coached practice in an interactive environment that fosters active learning A different paradigm, also having the potential to significantly improve learning, is collaborative learning Classroom learning improves significantly when students participate in structured learning activities in small groups of peers The educational value of student collaboration has led to the development of computer-supported collaborative learning (CSCL) tools These tools provide an exceptional learning environment but require at least two participants and do not offer students the type of individualized assistance and guidance available in an ITS A simulated learning companion, acting as a peer in an intelligent tutoring environment ensures the availability of a collaborator and encourages the student to learn collaboratively, while drawing upon the instructional advantages that ITSs provide The learning companion we designed encourages the student to reflect on and articulate his past actions, and to discuss his future intentions and their consequences This paper describes the issues raised in designing a learning companion for an existing ITS, and the benefits gained from this union

Reducing air traffic delay in a space-time network

Abstract: The author describes a formulation of National Airspace System (NAS) traffic management problem as a multicommodity minimum cost flow problem over a network in space-time. It is a formulation of the multidestination delay minimization problem of managing traffic in the NAS. The model's potential for improving over present practice is described in terms of six assumptions of present practice. The space-time network model can address uncertainty in capacity values, restrictive airways capacities, and hubbing. The minimum cost flow formulation further assumes that attempted entries into the system are deterministic, not Poisson, and that actual entries are controllable. The formulation specifically allows dynamic capacities and possesses good potential for short execution time. >

Rigorous automated network security management

Abstract: Achieving a security goal in a networked system requires the cooperation of a variety of devices, each device potentially requiring a different configuration Many information security problems may be solved with appropriate models of these devices and their interactions, giving a systematic way to handle the complexity of real situations We present an approach, rigorous automated network security management, that front-loads formal modeling and analysis before problem solving, thereby providing easy-to-run tools with rigorously justified results With this approach, we model the network and a class of practically important security goals The models derived suggest algorithms that, given system configuration information, determine the security goals satisfied by the system The modeling provides rigorous justification for the algorithms, which may then be implemented as ordinary computer programs requiring no formal methods training to operate We have applied this approach to several problems In this paper we describe two: distributed packet filtering and the use of IP security (IPsec) gateways We also describe how to piece together the two separate solutions to these problems, jointly enforcing packet filtering as well as IPsec authentication and confidentiality on a single network

The performance properties of electrically small resonant multiple-arm folded wire antennas

Abstract: In this tutorial article, the resonant radiation properties of electrically small, multiple-arm, folded wire antennas are considered and compared as a function of the antenna's height, the cylindrical diameter occupied, the geometry, and the number of folded arms within the antenna structure. The radiation properties considered include resonant resistance, efficiency, radiation patterns, and the operating bandwidth, which is characterized using the antenna's quality factor (Q). It is shown that electrically small, multiple-arm, folded wire antenna designs offer significant performance improvements relative to simple open-ended wire antennas, in terms of increased resonant resistance, bandwidth, and efficiency. However, when multiple-arm, folded wire antennas of the same height and cylindrical diameter, but having significantly different geometries, are made to be self-resonant at the same frequency, they exhibit similar resonant performance properties. This illustrates that the resonant performance properties of these antennas are primarily established by their height and the physical volume occupied relative to the resonant wavelength. Various design parameters are considered and described for achieving self-resonance and a reasonable impedance match with an electrically small, multiple-arm folded wire antenna. Finally, the performance properties of the multiple-arm folded wire configurations are compared with those of an impedance-matched, non-folded, open-ended wire configuration. It is shown that the multiple-arm folded wire configurations exhibit a lower Q than the impedance-matched, non-folded wire configuration.