Characterization and modeling of aperiodic pressure oscillations in combustion chambers

Classification of the long-term dynamical behavior of pressure oscillations in a laboratory combustion chamber has been performed using methods of modern dynamical systems theory. The method involves the construction of a phase-space representation from a single pressure record or time series using the time-delay embedding method. The pointwise correlation dimension of the resulting attractor in phase-space provides a lower bound on the number of modes that participate in the oscillations. The results show that the oscillations are quasiperiodic with a dimension near two over an order of magnitude of amplitudes. Quasiperiodicity is a result of the incommensurate frequencies of the system acoustic modes. A model for the dynamics is constructed by converting the governing equations to a kicked-oscillator model. When compared with the experimental data, the model results have similar pressure and velocity spectra and the attractor dimension verifies that quasiperiodic oscillations are present

A CLIPS prototype for autonomous power system control

The model of the system assumes a constant power source and loads (experiments) whose power demands exceed the supply. Experiments are described by their name, power consumption, time for a complete run, present status and the state of the load. The power consumption of each load is set at a constant level but can be dynamically modified by the operator. The status specifies if the experiment is running, paused, completed or failed. The state compensates for the lack of actual feedback sensor data, by signifying the stability of the load. Experiments are scheduled to keep as many running as possible with the current system limitations. A graphics oriented user interface is embedded into the rule-based system to enable an operator to easily experiment with the system

THE PETCHABUN PIEDMONT SURVEY: AN INITIAL INVESTIGATION OF THE PREHISTORY OF THE WESTERN BORDERS OF THE KHORAT PLATEAU, NORTHEAST THAILAND

Models of Southeast Asian prehistoric cultural development based on recent excavations in North and Northeast Thailand hypothesize that early village farming arose from the indigenous Hoabinhain occupation. The Petchabun Piedmont Survey was designed to test the particular idea expressed in those recent models that agriculture developed in a piedmont setting and in the form of a transition between mountain-oriented Hoabinhian hunting and gathering, and plains-oriented village farming. The survey covered eleven 10 x 10 km grid squares along the western piedmont borders of the Khorat Plateua, Northeast Thailand. Forty five sites were recorded and, subsequently, test excavations were conducted on three of these sites. The three excavated sites had similar ceramics and similar assemblages of other artifacts. Carbon-14 dates range in the first millenium B.C. Similarities between the excavated ceramics and surface ceramics from other sites demonstrate that most, and suggest that all, of the prehistoric open sites found in the survey pertain to the same cultural cluster. These were designated Phu Kradung ceramic sites. Four sites from an adjacent area surveyed by the Pa Mong project were also recognized as Phu Kradung ceramic sites. Neither the Petchabun Piedmont Survey nor the literature provide any evidence for Hoabinian, transitional, or early village farming occupation of this particular piedmont zone. Two major conclusions were drawn. First, extant models of Southeast Asian cultural development need to be reevaluated. Alternatives are discussed and another model is introduced in which agriculture arose from a shift in the subsistence base of hypothetical early plains occupants. Second, the survey results and current literature demonstrate that the Southeast Asian Iron Age witnessed settlement expansion and development of key elements of the enormously important wet rice agricultural complex. Data from the period are reviewed and some concluding suggestions are made as to their theoretical significance for studies of cultural development in Southeast Asia

Results of Significance Testing at 41DW269 Dewitt County, Texas

Site 41DW269 was tested by Texas Department of Transportation (TxDOT) archeologists in July of 1997. The investigations were conducted in the right-of-way of a proposed bridge replacement project on DeWitt County Road 122 at its crossing of Clear Creek. The investigations at Site 41DW269 consisted of mechanical trenching for archeological prospection and stratigraphic evaluation of the site, and the manual excavation of two 1 x 1 m test units and two shovel tests. Site 41DW269 is a multi-component terrace site with cultural deposits ranging in age from the Early Archaic through the Late Archaic. Two discrete alluvial fills, both containing cultural material, underlie the terrace. Unit 1 forms the core of the terrace and consists of a dark brown, sandy to silty loam to clay loam containing abundant secondary calcium carbonate. Unit 2 consists of a very dark grayish brown to black loam that represents a veneer of more recent overbank deposits that is approximately 1.0 to 1.2 m thick. In addition, two younger alluvial fills (Units 3 and 4) are present across the stream and at the base of the cutbank forming the northern site boundary. Testing of the site revealed two clearly distinct prehistoric cultural strata within deep alluvial deposits, and a single pit-like feature. The first cultural deposit is associated with Unit 1, and consists of a sparse assemblage of mineralized bone and lithic material extending from approximately 120-180 cm below the present ground surface. On the basis of a single radiocarbon age and a diagnostic Guadalupe tool, this component is believed to date to the Early Archaic. The second cultural deposit is associated with the upper veneer, and extends from approximately 10 cm to 110 cm below the surface. Although this deposit could not be subdivided based on the limited excavation data, it contains a cultural debris associated with Late Archaic and possibly Middle Archaic occupations Due to the deep and stratified nature of the deposits and the diversity of artifactual assemblages at the site, 41DW269 is considered eligible for inclusion in the National Register of Historic Places and for designation as a State Historic Landmark

Judging South Dakota Rangelands for Livestock and Wildlife Values

Judging South Dakota Rangelands for Livestock and Wildlife Values is a major advance in the approach to contest judging of South Dakota rangelands. For 25 years beginning in the mid-1970s, range judges identified plants and determined range site, range condition, and management practices for a given set of goals (Johnson et al., EC 731, 1979). In the mid-1990s, the need for a more contemporary judging contest was clear. Oklahoma led the way by changing the National Range Judging Contest in 1994. A year later, South Dakota followed. Several years of field tests and multiple revisions resulted in the current manual