A real-time method is presented to adoptively estimate three-dimensional unmodeled external torques acting on a spacecraft. This is accomplished by forcing the tracking error dynamics to follow the Lyapunov function underlying the feedback control law. For the case where the external torque is...

The efficient characterization of nonlinear systems is an important goal of vibration and model testing. The authors build a nonlinear system model based on the acceleration time series response of a single input, multiple output system. A series of local linear models are used as a template to...

Cost or performance targets for new bit technologies can be established with the aid of a drilling cost model. In this paper the authors make simplifying assumptions in a detailed drilling cost model that reduce the comparison of two technologies to a linear function of relative cost and...

Structural dynamic testing is concerned with estimation of system properties, including frequency response functions and modal characteristics. These properties are derived from tests on the structure of interest, during which excitations and responses are measured and Fourier techniques are...

It is common practice in system analysis to develop mathematical models for system behavior. Frequently, the actual system being modeled is also available for testing and observation, and sometimes the test data are used to help identify the parameters of the mathematical model. However, no...

Many structural components designed to support static loads must also demonstrate the ability to withstand low probability events that can produce impact loading. For some constructs the structure is not only subjected to the initial impact, but is also subjected to rebound impacts as well. In...

Field balancing can achieve significant results when other problems are present in the frequency spectrum and multiple vibrations are evident in the waveform. Many references suggest eliminating other problems before attempting to balance. That`s great - if you can do it. There are valid reasons...

The purpose of the research described in this paper was to examine the effects of using longer and heavier tractor-trailer combinations from the standpoint of the individual firm or shipper rather than from the viewpoint of the motor carrier. The objective was to determine the effect of longer...

National Institute of Standards and Technology (NIST) traceable standard weights serve as the foundation of mass measurement control programs. These standards are normally recalibrated annually at a cost of approximately $100 per weight. The Savannah River Site (SRS) has more than 4,000 standard...

The authors present a result on the robust stabilization of a class of nonlinear systems exhibiting parametric uncertainty. They consider feedback linearizable nonlinear systems with a vector of unknown constant parameters perturbed about a known value. A Taylor series of the system about the...