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.

Cancellation of diffuse jammer multipath by an airborne adaptive radar

Abstract: Airborne surveillance radars need to operate in an environment that can include the presence of ground clutter, standoff jammers, and diffuse jammer multipath. It is demonstrated here that a phased-array radar that employs adaptive spatial degrees of freedom, plus two different sets of adaptive temporal degrees of freedom can effectively cancel the aforementioned interference to an acceptable level. The two different sets of temporal taps required for each antenna element consist of one set spaced by the pulse repetition interval, so as to cancel ground clutter, and another spaced by about one-half of the reciprocal of the radar bandwidth, so as to cancel the diffuse jammer multipath which may enter through the main beam of the radar, as well as its sidelobes. Using the ideal covariance matrix, a simulation has been developed, and the necessary conditions for cancellation are analyzed and discussed. It is also shown that the cancellation can be performed either with the antenna elements or a set of beams, but that the beam space approach requires fewer space-time degrees of freedom for nearly the same level of cancellation as the element space approach. >

NeuroMorpho.Org implementation of digital neuroscience: dense coverage and integration with the NIF.

Abstract: Neuronal morphology affects network connectivity, plasticity, and information processing. Uncovering the design principles and functional consequences of dendritic and axonal shape necessitates quantitative analysis and computational modeling of detailed experimental data. Digital reconstructions provide the required neuromorphological descriptions in a parsimonious, comprehensive, and reliable numerical format. NeuroMorpho.Org is the largest web-accessible repository service for digitally reconstructed neurons and one of the integrated resources in the Neuroscience Information Framework (NIF). Here we describe the NeuroMorpho.Org approach as an exemplary experience in designing, creating, populating, and curating a neuroscience digital resource. The simple three-tier architecture of NeuroMorpho.Org (web client, web server, and relational database) encompasses all necessary elements to support a large-scale, integrate-able repository. The data content, while heterogeneous in scientific scope and experimental origin, is unified in format and presentation by an in house standardization protocol. The server application (MRALD) is secure, customizable, and developer-friendly. Centralized processing and expert annotation yields a comprehensive set of metadata that enriches and complements the raw data. The thoroughly tested interface design allows for optimal and effective data search and retrieval. Availability of data in both original and standardized formats ensures compatibility with existing resources and fosters further tool development. Other key functions enable extensive exploration and discovery, including 3D and interactive visualization of branching, frequently measured morphometrics, and reciprocal links to the original PubMed publications. The integration of NeuroMorpho.Org with version-1 of the NIF (NIFv1) provides the opportunity to access morphological data in the context of other relevant resources and diverse subdomains of neuroscience, opening exciting new possibilities in data mining and knowledge discovery. The outcome of such coordination is the rapid and powerful advancement of neuroscience research at both the conceptual and technological level.

Dual-band quadrifilar helix antenna

Abstract: Resonant quadrifilar helix antennas are widely used on hand-held receivers for GPS (Global Positioning System) and for some mobile communication systems. The paper investigates a quadrifilar helix antenna over a ground plane and with trap loading. A model of this antenna was built to operate at two frequency bands, 1227 MHz and 1575 MHz, with more than 2% bandwidth in each band. The four wires of the helix were created using narrow copper strips on a flexible mylar sheet that is then rolled into a cylinder to form the helix. The trap circuit is placed across the gap in each strip. To obtain anti-resonance at the higher frequency, the trap circuit values are 6.8 nH and 1.5 pF. The four arms of the helix are attached to a base plate whose diameter is chosen to reflect the energy from the helix while still maintaining coverage for angles just below the horizon, a cardioid pattern. Examples of the right-hand circular polarization elevation plane patterns measured at those two frequencies are shown. The input match for the antenna is illustrated by an overlay of the reflection coefficients at the input to each of the four arms of the helix.

Uncertainty reasoning for the world wide web: report on the URW3-XG incubator group

Abstract: The Uncertainty Reasoning for the World Wide Web Incubator Group (URW3-XG) was chartered as a means to explore and better define the challenges of reasoning with and representing uncertain information in the context of the World Wide Web. The objectives of the URW3-XG were: (1) To identify and describe situations on the scale of the World Wide Web for which uncertainty reasoning would significantly increase the potential for extracting useful information; and (2) To identify methodologies that can be applied to these situations and the fundamentals of a standardized representation that could serve as the basis for information exchange necessary for these methodologies to be effectively used. This paper describes the activities undertaken by the URW3-XG, the recommendations produced by the group, and next steps required to carry forward the work begun by the group.