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 The Dominion of Design

Archive for February, 2013

Using Simulation to Optimize Safety, Performance, and Cost Savings When Integrating an Antenna Onto a Platform

Thursday, February 7th, 2013

Article source: Remcom

Successful integration of an antenna onto a vehicle platform poses many challenges.  Vehicle features impact antenna performance by blocking, reflecting or reradiating energy, and co-site interference can impair the effectiveness of multi-antenna configurations.  Platform motion and environmental factors such as terrain and buildings may reduce system effectiveness in actual op
erational conditions.  Furthermore, radiation hazards may pose risks to nearby personnel.  Modeling and simulation provides a powerful tool to aid in understanding these issues and developing solutions.  This article provides a variety of examples of simulation-based assessments used to analyze antenna performance, identify problems, and evaluate potential solutions.

The key benefit of simulation-based assessment is that it is relatively fast and cost-effective compared to physical system modification and measurement.  The lead times and costs associated with scheduling measurements in an anechoic chamber or at an outdoor test facility sometimes strain schedules and budgets.  Modeling and simulation can assess options and tradeoffs in order to select a small number of planned approaches well before any physical testing occurs; as a result, experimental design focuses on verifying planned approaches and fine-tuning alternatives demonstrated to be effective in simulations.  This approach reduces the risk of encountering problems that require retesting, costly redesign or introduce dangerous in-theater behavior.

In addition, a number of challenges arise when attempting to perform exhaustive laboratory or field testing on an integrated system.  Some potential issues include:

  • Available measurement facilities may not be able to accommodate larger platforms
  • Facilities may not be able to handle the full range of frequencies for the system(s) under test
  • Comprehensive in situ measurements may be difficult or impractical for operational conditions (e.g., aircraft in flight or a HMMWV in an urban environment)
  • In-theater modifications could require additional testing

A comprehensive modeling and simulation toolset allows an organization to overcome these challenges by being able to simulate any number of conditions, identify and resolve key issues, and reserve the use of physical measurements to confirm successful pre-test, simulation-based assessments.  The remainder of this article provides several examples demonstrating typical simulation-based assessments to identify and resolve issues related to antenna performance and integration onto vehicles.


MIT researchers improve quantum-dot performance

Monday, February 4th, 2013

Written by: David L. Chandler, MIT News Office

New production method could enable everything from more efficient computer displays to enhanced biomedical testing.

CAMBRIDGE, Mass. — Quantum dots — tiny particles that emit light in a dazzling array of glowing colors — have the potential for many applications, but have faced a series of hurdles to improved performance. But an MIT team says that it has succeeded in overcoming all these obstacles at once, while earlier efforts have only been able to tackle them one or a few at a time.

Moungi G. Bawendi

Quantum dots — in this case, a specific type called colloidal quantum dots — are tiny particles of semiconductor material that are so small that their properties differ from those of the bulk material: They are governed in part by the laws of quantum mechanics that describe how atoms and subatomic particles behave. When illuminated with ultraviolet light, the dots fluoresce brightly in a range of colors, determined by the sizes of the particles.

First discovered in the 1980s, these materials have been the focus of intense research because of their potential to provide significant advantages in a wide variety of optical applications, but their actual usage has been limited by several factors. Now, research published this week in the journal Nature Materials by MIT chemistry postdoc Ou Chen, Moungi Bawendi, the Lester Wolfe Professor of Chemistry, and several others raises the prospect that these limiting factors can all be overcome.

The new process developed by the MIT team produces quantum dots with four important qualities: uniform sizes and shapes; bright emissions, producing close to 100 percent emission efficiency; a very narrow peak of emissions, meaning that the colors emitted by the particles can be precisely controlled; and an elimination of a tendency to blink on and off, which limited the usefulness of earlier quantum-dot applications.


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