The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

This report provides the equation formulation for a large-eddy simulation (LES) approach and Smagorinsky subgrid-scale (SGS) model for incompressible flow using the finite element method (FEM). This report also outlines the model implementation in the computer code HYDRA and the results of a coding check. The check was accomplished by running simple two- and three-element problems for a specified velocity field. The values of the eddy viscosity (the coefficient of proportionality in the SGS eddy diffusion model), the SGS diffusion term, and overall diffusion term (molecular plus SGS plus balancing tensor diffusivity) were compared to known hand-calculated values. Coding checks are best done by comparing the code-calculated solution to known analytical solutions. However, with LES turbulence modeling, these analytical solutions do not exist. It is also impossible to determine that the eddy viscosity is free of coding errors when performing code validation by comparing the LES to direct numerical simulations (DNS) (i.e., fine discretization with no turbulence model) or experimental results. Therefore, the coding checks presented here for a specified velocity field are necessary.

Radioactive nuclear beams are rapidly coming to the fore as an important alternative to traditional measurements in nuclear astrophysics. Radioactive nuclei are scattered off the strong electromagnetic fields of a heavy ion, such as lead, providing an independent measurement of electromagnetic cross sections that are difficult to measure otherwise. In this paper, we examine the corrections to the semi-classical ``equivalent photon spectrum`` used to analyze these experiments, and derive an improved spectrum, valid in the long wavelength limit, that includes the effects of the size of the heavy ion, the non-zero longitudinal momentum transfer required by kinematics, and the response of the target nucleus to be off-shell photon.

In the analysis of turbulent flow, the evaluation of simulations is difficult because the results are three-dimensional and transient. We have found that analysis of the power spectra from the nodal time histories provides not only insight into the behavior of the flow, but it is a useful tool in determining the solution`s spatial (grid) and temporal (time step) convergence. We have developed a method and computer code for calculating the power spectrum for any set of equal-interval data. The code is called PWRSPEC. This report documents the method used to calculate the power spectrum, provides guidance on how to use the PWRSPEC code, and includes an example problem that was used for code validation.

In early 1991, the Security Council of the United Nations tasked the Director General of the International Atomic Energy Agency, with the assistance and cooperation of the United Nations Special Commission, to oversee the destruction, removal or rendering harmless of nuclear weapons material and capabilities in Iraq. The conduct of the nuclear inspections, and the subsequent activities (identification, destruction, removal rendering harmless), have provided a wealth of experience and insight into the inspection and monitoring process as well as into the political realities of such an operation. The early inspections were conducted in an atmosphere of discovery and inexperience on both the part of the Iraqis and the IAEA and UNSCOM. As time went on, the Iraqis became more adept at hiding and obscuring relevant documents and equipment, and the inspection teams became more knowledgeable about inspection and investigative techniques, and the pre-existing Iraqi programs. A continuous monitoring presence in Iraq has now been established and an import/export monitoring regime is being developed. While steps taken to date have proven effective in inhibiting resumption of nuclear weaponization activities, it remains to be seen how effective these measures will be in the future. The external and internal conditions which led the …

Terrain coverage problems are nearly as old as mankind: they were necessary early in our history for basic activities such as finding food and other necessities. As our societies and their associated machineries have grown more complex, we have not outgrown the need for this primitive skill. It is still used on a small scale for cleaning tasks and on a large scale for {open_quotes}search and report{close_quotes} missions of various kinds. The motivation for automating this process may not lie in the novelty of anything we might gain as an end product, but in freedom from something which we as humans find tedious, time-consuming and sometimes dangerous. Here we consider autonomous coverage of a terrain, typically indoor rooms, by a mobile robot that has no a priori model of the terrain. In evaluating its surroundings, the robot employs only inexpensive and commercially available ultrasonic and infrared sensors. The proposed solution is a basic step - a proof of principle - that can contribute to robots capable of autonomously performing tasks such as vacuum cleaning, mopping, radiation scanning, etc. The area of automatic terrain coverage and the closely related problem of terrain model acquisition have been studied both analytically and experimentally. …

This publication provides information and statistical data on a variety of crude oils and refined petroleum products. It presents statistics on crude oil costs and refined petroleum products sales for use by industry, government, private sector analysts, educational institutions, and consumers. Data on crude oil include domestic first purchase price, f.o.b. and landed cost of imported crude, and refiners` acquisition cost of crude. Refined petroleum product sales data include motor gasoline, distillates, residuals, aviation fuels, kerosene, and propane.