Investigation of Flight Test Methods for measuring the performance of general aviation aircraft

A theoretical and experimental investigation of methods for measuring the performance of general aviation airplanes was conducted using relatively simple instrumentation currently available and data extraction techniques established from efforts in other disciplines. The possibilities of improving flight test data by use of improved modern instrumentation and digital data recording and data analysis were considered

A sophisticated, multi-channel data acquisition and processing system for high frequency noise research

A sophisticated, multi-channel computerized data acquisition and processing system was developed at the NASA LeRC for use in noise experiments. This technology, which is available for transfer to industry, provides a convenient, cost-effective alternative to analog tape recording for high frequency acoustic measurements. This system provides 32-channel acquisition of microphone signals with an analysis bandwidth up to 100 kHz per channel. Cost was minimized through the use of off-the-shelf components. Requirements to allow for future expansion were met by choosing equipment which adheres to established industry standards for hardware and software. Data processing capabilities include narrow band and 1/3 octave spectral analysis, compensation for microphone frequency response/directivity, and correction of acoustic data to standard day conditions. The system was used successfully in a major wind tunnel test program at NASA LeRC to acquire and analyze jet noise data in support of the High Speed Civil Transport (HSCT) program

THE SPECTROSCOPY OF CRYSTAL DEFECTS - A COMPENDIUM OF DEFECT NOMENCLATURE

The authors bring together tables of current defect nomenclature and a summary of the rules actually practised (rather than idealised schemes) in choosing such labels for signals obtained with a range of spectroscopies. As well as providing a source of reference for the user lost in a maze of labels, the compilation also indicates parallels between similar defect species in very different systems (e.g. ice and quartz), even though the relationships may be far from obvious from the labels. The systems considered are all non-metals, namely ionic crystals (including oxides), silica, semiconductors (e.g. III-V and tetrahedrally coordinated II-VI), valence crystals (e.g. diamond, c-Si, a-Si) and other special hosts like ice and conducting polymers

Transverse instability and its long-term development for solitary waves of the (2+1)-Boussinesq equation

The stability properties of line solitary wave solutions of the (2+1)-dimensional Boussinesq equation with respect to transverse perturbations and their consequences are considered. A geometric condition arising from a multi-symplectic formulation of this equation gives an explicit relation between the parameters for transverse instability when the transverse wavenumber is small. The Evans function is then computed explicitly, giving the eigenvalues for transverse instability for all transverse wavenumbers. To determine the nonlinear and long time implications of transverse instability, numerical simulations are performed using pseudospectral discretization. The numerics confirm the analytic results, and in all cases studied, transverse instability leads to collapse.Comment: 16 pages, 8 figures; submitted to Phys. Rev.

Replacement Female Strategies

Most beef operations are reliant on the generation of replacement heifers. Replacement heifers are intended to replace old or non-productive cows, incorporate new and hopefully improved genetics into the herd, and be productive females as young cows and then subsequently deliver several more generations of calves. Thus, there are both short-term and long-term objectives when selecting and developing replacement beef heifers. As such, implementing proper selection criteria, growth and developmental strategies, health and nutritional management, and breeding programs for replacement beef heifers are essential to meet both short-term and long-term objectives of the operation. From a short-term standpoint, retaining and developing a replacement heifer represents a considerable investment. Failing to properly develop a young female may limit her ability to reach puberty, conceive, and calf. In addition, improper development can impede her ability to stay in the herd for more than a few years and impact her progenies performance. From a long-term perspective, the future genetic make-up of the cowherd is contingent on the decisions made when selecting and developing the replacement heifers. Thus, the genetic composition and production traits of the beef herd for the next seven to ten years is derived from heifer selection done today. This article focuses on targeted breeding systems to yield potential replacements, selection of replacements, and management practices and nutritional delivery for developing replacement beef heifers