The purpose of this research was to validate the Ionospheric Forecast Model (IFM) Version 3 to assess its suitability and usefulness as an operational tool. The Ionospheric forecast model is a first principles computer model designed to forecast the state of the global ionosphere to 24 hours. The scope was limited to a comparison of the F2 layer critical frequency (foF2) and peak electron density (hmF2) against observed ionosonde data. The model was run with global solar and geomagnetic indices and Information from Digitial Ionospheric Sounding System (DISS) observations as inputs. The DISS observations were input through the Parameterized Real-Time Ionospheric Specification Model (PRISM). The IFM was run for a total of 25 days. It was run twice for each 24- hour period: once by starting with only an initial specification of the ionosphere from an empirical model, and again, with an initial specification from the PRISM model with DISS data as an input.

The federal government supports infrastructure investment in a variety of ways. However, the most common means of providing a tax subsidy for infrastructure investment, by offering a tax exemption for interest on state and local bonds, is generally viewed to be an inefficient way to subsidise state and local borrowing, largely because the revenue cost to the federal government may exceed the interest-cost subsidy provided to state and local governments by a substantial amount. This book assesses the role of tax preferences in infrastructure investments in the United States and discusses the types of tax preferences for state and local bonds, and it also considers how the current system of tax preference might change as a result of greater use of tax-credit bonds.