Robert B. Webster

Theoretical and experimental studies of CO2 laser evaporation of clouds

A study of the effects of laser radiation on cloud drops and of the possibility of producing a clear optical channel in a cloud is presented. In order to produce a model that is appropriate to a realistic cloud with a distribution of drop sizes it is first necessary to study what happens to a single water drop subjected to laser radiation of different intensities. Various heating regimes are mapped out as a function of laser flux and fluence at the 10.6 μm wavelength. It is found that typical cloud drops can superheat until they become unstable and explode from the center. For a long laser pulse the boundary for this to occur is found to be 50(5/r)2 kW/cm2, where r is the drop radius in microns. Using these results a model that is spatially one‐dimensional through the cloud is constructed for a distribution of drop sizes. Laser beam intensity as the light penetrates a cloud is calculated from Mie scattering and absorption cross sections for a beam diameter that is small in the sense that light scattered o...

Automated parametric execution and documentation for large-scale simulations

A language has been created to facilitate the automatic execution of simulations for purposes of enabling parametric study and test and evaluation. Its function is similar in nature to a job-control language, but more capability is provided in that the language extends the notion of literate programming to job control. Interwoven markup tags self document and define the job control process. The language works in tandem with another language used to describe physical systems. Both languages are implemented in the Extensible Markup Language (XML). A user describes a physical system for simulation and then creates a set of instructions for automatic execution of the simulation. Support routines merge the instructions with the physical-system description, execute the simulation the specified number of times, gather the output data, and document the process and output for the user. The language enables the guided exploration of a parameter space and can be used for simulations that must determine optimal solutions to particular problems. It is generalized enough that it can be used with any simulation input files that are described using XML. XML is shown to be useful as a description language, an interchange language, and a self-documented language.

Analyzing use cases for knowledge acquisition

The analysis of use cases describing construction of simulation configuration files in a data/information management system can lead to the acquisition of new information and knowledge. In this application, a user creates a use case with an eXtensible Markup Language (XML) description representing a configuration file for simulation of a physical system. INtelligent agents analyze separate versions of the XML descriptions of a user and additionally, make comparisons of the descriptions with examples form a library of use cases. The agents can then make recommendations to a user on how to proceed or if tutoring is necessary. In a proof-of-concept test, new information is acquired and a user learns from the agent-facilitated tutoring.

An object-based methodology for knowledge representation in SGML

An object-based methodology for knowledge representation and its Standard Generalized Markup Language (SGML) implementation is presented. The methodology includes class, perspective, domain and event constructs for representing knowledge within an object paradigm. The perspective construct allows for the representation of knowledge from multiple and varying viewpoints. The event construct allows actual use of knowledge to be represented. The SGML implementation of the methodology facilitates usability, structured, yet flexible knowledge design, and sharing and re-use of knowledge class libraries.

Advanced Reservoir Management For Independent Oil And Gas Producers

There are more than fifty-two hundred oil and gas producers operating in the United States today. Many of these companies have instituted improved oil recovery programs in some form, but very few have had access to state-of-the-art modeling technologies routinely used by major producers to manage these projects. Since independent operators are playing an increasingly important role in the production of hydrocarbons in the United States, it is important to promote state-of-the-art management practices, including the planning and monitoring of improved oil recovery projects, within this community. This is one of the goals of the Strategic Technologies Council, a special interest group of independent oil and gas producers. Reservoir management technologies have the potential to increase oil recovery while simultaneously reducing production costs. These technologies were pioneered by major producers and are routinely used by them. Independent producers confront two problems adopting this approach: the high cost of acquiring these technologies and the high cost of using them even if they were available. Effective use of reservoir management tools requires, in general, the services of a professional (geoscientist or engineer) who is already familiar with the details of setting up, running, and interpreting computer models.

Cloud hole boring with long pulse CO 2 lasers: theory and experiment

Chemically generated CO(2) laser pulses at 10.6 microm have been used to clear a 5-cm diameter hole through a stratus-like cloud in a laboratory cloud chamber. The results show that 100% clearing can be achieved. The mechanism is shown to be droplet shattering followed by evaporation. In the experimental conditions, the channel closure is effected by turbulent mixing and droplet recondensation.

Using multiple perspectives to suppress information and complexity

Dissemination of battlespace information involves getting information to particular warfighters that is both useful and in a form that facilitates the tasks of those particular warfighters. There are two issues which motivate this problem of dissemination. The first issue deals with disseminating pertinent information to a particular warfighter. This can be thought of as information suppression. The second issue deals with facilitating the use of the information by tailoring the computer interface to the specific tasks of an individual warfighter. This can be thought of as interface complexity suppression. This paper presents a framework for suppressing information using an object-based knowledge representation methodology. This methodology has the ability to represent knowledge and information in multiple perspectives. Information can be suppressed by creating a perspective specific to an individual warfighter. In this way, only the information pertinent and useful to a warfighter is made available to that warfighter. Information is not removed, lost, or changed, but spread among multiple perspectives. Interface complexity is managed in a similar manner. Rather than have one generalized computer interface to access all information, the computer interface can be divided into interface elements. Interface elements can then be selected and arranged into a perspective-specific interface. This is done in a manner to facilitate completion of tasks contained in that perspective. A basic battlespace domain containing ground and air elements and associated warfighters is used to exercise the methodology.

Improved Oil Recovery for Independent Oil & Gas Producers

There are more than fifty-two hundred independent oil and gas producers operating in the US today (based on current IPAA membership figures). Many of these companies have instituted improved oil recovery programs in some form, but very few have had access to the state-of-the-art modeling technology routinely used by major producers to manage these projects. Since independent operators are playing an increasingly important role in production of hydrocarbons in the US, it is important to promote state-of-the-art management practices, including the planning and monitoring of improved oil recovery projects, within this community. This is one of the goals of the Strategic Technologies Council, a special interest group of Independent Oil and Gas producers. This paper describes a project which focuses on the distribution of advanced reservoir management technologies (geological, petrophysical, and engineering) to independent producers. The evolving information highway serves as the distribution medium, specifically the World Wide Web (W3). The procedure for launching petrotechnical applications and retrieving results over the W3 will be presented. A paradigm for the interaction between the independents, the petroleum service sector, and government will also be presented. Of principal concern is the cost of making high-tech modeling applications accessible to independent operators.

Fuzzy attributes for knowledge representation and acquisition

Repertory grids and other matrix-like structures can be used to represent knowledge and elicit knowledge from experts. A grid or matrix is a representation of a knowledge domain where the elements in the domain appear along the horizontal axis and constructs or attributes of the elements appear along the vertical axis. Each construct is rated for its presence in a given element or how much a construct applies to an element. Analysis of these ratings can determine similarities and differences between the elements. Traditionally, constructs are bipolar entities where a rating falls on a range from one pole to the other. For example, temperature may be represented by the bipolar construct hot-cold and a range of 1 to 5 in which 1 represents hot and 5 represents cold. Ratings of 2, 3, and 4 lie in-between hot and cold. Additionally, all constructs in a grid have the same range of values and the range is arbitrarily chosen. This paper presents a method for translating grid ratings into fuzzy membership values. The fuzzy membership values become the values for describing and analyzing the associations between elements. Thus, constructs no longer need to use the same scaling range and no longer need to be bipolar. A construct of an element now becomes a true attribute of an element. An attribute can be rated in its own range and with its own unit of measurement. In the previous example, the bipolar construct hot-cold becomes simply, temperature measured in degrees. Experts or users need no longer translate to an artificial rating range.

Cloud hole-boring with long pulse CO2 lasers

Chemically generated CO laser pulses at 10.6 im have been used to clear a 5cm diameter hole through a stratus-like cloud in a laboratory cloud chamber. The results show that 100% clearing can be achieved. The mechanism is shown to be droplet shattering followed by evaporation. Under the conditions of the experiment, the channel closure is dominated by turbulent mixing and not droplet recondensation.