Aircraft noise synthesis system

A second-generation Aircraft Noise Synthesis System has been developed to provide test stimuli for studies of community annoyance to aircraft flyover noise. The computer-based system generates realistic, time-varying, audio simulations of aircraft flyover noise at a specified observer location on the ground. The synthesis takes into account the time-varying aircraft position relative to the observer; specified reference spectra consisting of broadband, narrowband, and pure-tone components; directivity patterns; Doppler shift; atmospheric effects; and ground effects. These parameters can be specified and controlled in such a way as to generate stimuli in which certain noise characteristics, such as duration or tonal content, are independently varied, while the remaining characteristics, such as broadband content, are held constant. The system can also generate simulations of the predicted noise characteristics of future aircraft. A description of the synthesis system and a discussion of the algorithms and methods used to generate the simulations are provided. An appendix describing the input data and providing user instructions is also included

Effects of pit construction, crate design, and ventilation rate on the air velocities in a model swine farrowing house

This research was performed to evaluate the air flow characteristics of a model totally enclosed swine farrowing house with partially slotted floors. A 1/8 scale model was designed and constructed according to the principles of similitude, and a laboratory experiment was conducted. The effects of pit ventilation duct construction, farrowing crate design, and ventilation rate were studied. Two replications of the 13 treatments of the experiment were made. The two types of pit ventilation construction included a PVC pipe duct system and a center masonry duct system. Open and solid side farrowing crates were tested along with three rates of ventilation. Control treatments consisting of no pit ventilation, solid side crates, and medium ventilation rate were also tested. Air velocities were measured and recorded at 144 points within the model for each treatment. There was good agreement between the velocities of the two experiment replications. Although the coefficients of variation were similar to those reported from other studies, the velocities did not follow a pattern which could easily be mathematically predicted as a function of location within the model. Most of the conclusions reached in previous studies have been based on average air velocities. Since the average air velocities found in this study often did not correlate with the minimum air velocities, the concept of using minimum air velocity as a ventilation system evaluation criterion was investigated. The air velocities were not much different for the two types of pit ventilation ducts - either at the pig level or at the sow nose locations. Minimum air velocities were all lower when no pit ventilation was used. The minimum air velocities at both the pig and the sow levels were higher for the open side crate treatments than for the treatments using solid side crates. The air velocities resulting from the low ventilation rates were much less uniform than those produced by the high ventilation rates. The minimum air velocities at the pig level, the sow level, and the level near the ceiling increased as the ventilation rate increased

Aircraft noise synthesis system: Version 4 user instructions

A modified version of the Aircraft Noise Synthesis System with improved directivity and tonal content modeling has been developed. The synthesis system is used to provide test stimuli for studies of community annoyance to aircraft flyover noise. The computer-based system generates realistic, time-varying audio simulations of aircraft flyover noise at a specified observer location on the ground. The synthesis takes into account the time-varying aircraft position relative to the observer; specified reference spectra consisting of broadband, narrowband, and pure tone components; directivity patterns; Doppler shift; atmospheric effects; and ground effects. These parameters can be specified and controlled in such a way as to generate stimuli in which certain noise characteristics such as duration or tonal content are independently varied while the remaining characteristics such as broadband content are held constant. The modified version of the system provides improved modeling of noise directivity patterns and an increased number of pure tone components. User instructions for the modified version of the synthesis system are provided

Southwestern Pecan Orchard Soil Standards

The Rio Grande Basin in southern New Mexico and western Texas has become a large source of commercially produced pecans over the past few decades, yet agronomic research specific to soil management and fertilization in this area has not yet been fully developed. This project aims to review the currently published optimal soil analysis ranges as well as to identify significant relationships between soil characteristics and yield which merit further investigation. Over the 2012 growing period, 106 production blocks in Dona Ana County were observed. Soil analysis was conducted on each block prior to budbreak and after harvest to review soil changes over the full growth cycle; yield and tree counts were also collected. Due to alternate bearing in pecans, yield has been analyzed in four population groupings: “ON” blocks only, “OFF” blocks only, all blocks using a two year yield average, and all blocks using a dummy variable to isolate the alternate bearing yield differences. Mixed regression models were used to identify optimal levels and significant relationships within all four groupings. Of the production blocks observed, the soil analysis results fell within only 22% of the published optimal ranges, which are not crop specific. Boron, Bulk Density, Copper, Iron, Magnesium, Manganese, and Zinc were all identified as exhibiting significant, largely negative, relationships with yield, suggesting that these variables may be inhibiting production. The observed relationships merit further investigation and optimal soil analysis ranges must be developed in order to ensure correct interpretation of results and subsequent soil management practices