A study on the effect of building on the HF direction finding
The effect of new building on the high-frequency (HF) direction finding (DF) is analyzed. Commercially available software is used to get array manifold of the HF DF system taking the effect of the new building into account. The terrain, building and the array antenna system are modeled. The new building near the antenna system is also modeled to see whether it actually has an effect on the performance of the DF system. Interferometer DF algorithms has been employed.
The Effect of Ground Reflections and Scattering on an Interferometer Direction Finder
The azimuth and elevation angles of an airborne beacon transmitter can be determined using a direction finder comprised of two orthogonal interferometers located near the earth's surface. In this paper we consider the reflection of the incident electromagnetic field by the earth's surface and the resultant effect on the direction-finding system. The analysis yields an upper bound or limit to the interferometer phase error and the corresponding error in bearing angle that can result because of specular reflection and diffuse scattering.
Case study: performance effectiveness and cost-benefit analyses of open-graded friction course pavements in Tennessee
Abstract The effectiveness and cost-benefit of Open-Graded Friction Course (OGFC) pavements were analysed in this study by investigating the cost, field performance, short- and long-term effectiveness, and accident rate of OGFC projects in Tennessee. Paired sample t-tests were conducted to compare if there was significant difference between OGFC and non-OGFC sections. Investigation on the performance effectiveness showed that OGFC sections provided comparable performance level as traditional dense mix overlays and were effective in improving pavement performance and repairing deterioration except for rutting potential. However, no severe pavement deterioration was observed on the OGFC sections after more than four or five years of service, indicating sufficient durability of the OGFC used in Tennessee where mild freeze-thaw cycles are experienced annually. Although the unit cost ($/m3) of OGFC was about 42% higher than the cost of traditional dense mix overlays, it was observed that the accident rate was significantly reduced especially in rainy days after the OGFC treatment. The cost-benefit analyses based on the ratio of accident rate reduction over cost demonstrated that OGFC was significantly more cost-beneficial in improving driving safety and reducing accident rate in rainy days.