Peter T. Davis

Learn More
At periods greater than 1000 seconds, Earth's seismic free oscillations have anomalously large amplitude when referenced to the Harvard Centroid Moment Tensor fault mechanism, which is estimated from 300- to 500-second surface waves. By using more realistic rupture models on a steeper fault derived from seismic body and surface waves, we approximated free(More)
In this paper, we describe an interactive system, built within the context of CLiMB project, which permits a user to locate the occurrences of named entities within a given text. The named entity tool was developed to identify references to a single art object (e.g. a particular building) with high precision in text related to images of that object in a(More)
Metadata descriptions of database contents are required to build and use systems that access and deliver data in response to user requests. When numerous heterogeneous databases are brought together in a single system, their various metadata formalizations must be homogenized and integrated in order to support the access planning and delivery system. This(More)
An obstacle to understanding results across heterogeneous databases is the ability to determine conceptual connections between differing terminologies. In this paper, we present the two step approach which we have used to build a terminological database in order to address this issue. First we automatically built a heterogeneous collection of terms and(More)
Onset of chaotic mode transitions can be used in a simple and robust mechanism for adaptation in multimode systems. We present an idealized model of adaptive mode selection using on-oo switching of chaotic basin transition a multistable system. A stochastic description obtained in the limit of l switching intervals gives search times in terms of projections(More)
The Digital Government Research Center (DGRC) has completed phase one of the Energy Data Collection (EDC) project. In this paper, we present the results of building and evaluating system components, along with plans for phase two of the project. Phase one focused on data about petroleum products' prices and volumes, provided by the Energy Information(More)
BACKGROUND Due to the lower health risks associated with the use of certain categories of smokeless tobacco products (STPs) such as Swedish snus, there is interest in the comparative levels of toxic chemical constituents in different types of STPs. A method has been developed and validated for the analysis of hydrazine in STPs. Seventy four commercial STPs(More)
—We experimentally investigate the synchronous response of a semiconductor laser to the injection of a periodic or chaotic oscillating optical signal that is generated by a similar semiconductor laser with optical feedback. We show that there are two different types of synchronous response, appearing in separate regimes of laser frequency detuning and(More)
  • 1