Comparison of 13CO Line and Far-Infrared Continuum Emission as a Diagnostic of Dust and Molecular Gas Physical Conditions: I. Motivation and Modeling

Determining temperatures in molecular clouds from ratios of CO rotational lines or from ratios of continuum emission in different wavelength bands suffers from reduced temperature sensitivity in the high-temperature limit. In theory, the ratio of far-IR, submillimeter, or millimeter continuum to that of a 13CO (or C18O) rotational line can place reliable upper limits on the temperature of the dust and molecular gas. Consequently, far-infrared continuum data from the {\it COBE}/{\it DIRBE} instrument and Nagoya 4-m \cOone spectral line data were used to plot 240\um/13CO J=1-0 intensity ratios against 140\um/240\um dust color temperatures, allowing us to constrain the multiparsec-scale physical conditions in the Orion$$A and B molecular clouds. The best-fitting models to the Orion clouds consist of two components: a component near the surface of the clouds that is heated primarily by a very large-scale (i.e. $\sim 1$kpc) interstellar radiation field and a component deeper within the clouds. The former has a fixed temperature and the latter has a range of temperatures that varies from one sightline to another. The models require a dust-gas temperature difference of 0$\pm 2$K and suggest that 40-50% of the Orion clouds are in the form of dust and gas with temperatures between 3 and 10$$K. These results have a number implications that are discussed in detail in later papers. These include stronger dust-gas thermal coupling and higher Galactic-scale molecular gas temperatures than are usually accepted, an improved explanation for the N(H$_2$)/I(CO) conversion factor, and ruling out one dust grain alignment mechanism.Comment: The second version includes some discussion of why previous models of dust-gas thermal coupling were simplistic. Paper III in the series discusses this in more detail. Also, some minor errors were corrected. These errors in no way affect the final conclusion

Welding skate with computerized control Patent

Development of apparatus for automatically changing carriage speed of welding machine to obtain constant speed of torch along work surfac

Welding skate with computerized controls

New welding skate concept for automatic TIG welding of contoured or double-contoured parts combines lightweight welding apparatus with electrical circuitry which computes the desired torch angle and positions a torch and cold-wire guide angle manipulator

Computerized adaptive control weld skate with CCTV weld guidance project

This report summarizes progress of the automatic computerized weld skate development portion of the Computerized Weld Skate with Closed Circuit Television (CCTV) Arc Guidance Project. The main goal of the project is to develop an automatic welding skate demonstration model equipped with CCTV weld guidance. The three main goals of the overall project are to: (1) develop a demonstration model computerized weld skate system, (2) develop a demonstration model automatic CCTV guidance system, and (3) integrate the two systems into a demonstration model of computerized weld skate with CCTV weld guidance for welding contoured parts

Flare angles measured with ball gage

Precision tungsten carbide balls measure the internal angle of flared joints. Measurements from small and large balls in the flare throat to an external reference point are made. The difference in distances and diameters determine the average slope of the flare between the points of ball contact

Fannie Mae's and Freddie Mac's voluntary initiatives: Lessons from banking

The federal government has an interest in the financial stability of Fannie Mae and Freddie Mac because of their importance to financial markets and the government's implicit guarantee of their liabilities. ; In October 2000 these two housing government-sponsored enterprises (GSEs) announced six voluntary initiatives. One initiative would enhance market discipline by having the GSEs issue subordinated debt. A second would boost liquidity by having the GSEs maintain a liquid securities portfolio. The other four initiatives would increase transparency by having the GSEs disclose their credit and interest rate losses under certain scenarios, obtain a credit rating for the government's exposure to loss, and disclose whether the GSEs comply with certain capital adequacy standards. ; This article evaluates the initiatives from the perspective of current banking standards. The analysis suggests that the initiatives are beneficial but could be made more effective. The authors point out that the contribution of the subordinated debt initiative depends largely on whether investors believe the implicit guarantee extends to subordinated debtholders. The need for the liquidity initiative has not been established, the authors conclude, and can be criticized as allowing the GSEs to earn a credit spread. The most important of the disclosure initiatives, the one for interest rate risk, will provide some new information but could be more informative if it summarized a wider set of interest rate scenarios.Government-sponsored enterprises ; Federal Home Loan Mortgage Corporation ; Federal National Mortgage Association ; Federal home loan banks

Financing housing through government-sponsored enterprises

Three government-sponsored enterprises (GSEs)-Fannie Mae, Freddie Mac, and the Federal Home Loan Bank System-were created to improve the availability of home mortgage financing by supplementing local funding. But today's more evolved financial markets enable retail lenders to tap national markets. Thus, the main contribution of the three housing GSEs has become providing homebuyers an interest rate subsidy that is made possible by the GSEs' special relationship with the federal government. ; This article examines the economic issues arising from the provision of such subsidies via the housing GSEs. The authors first review the benefits and costs of subsidizing housing finance and then provide background information about the housing GSEs and their relationship to the federal government. The GSEs' importance to the financial markets, coupled with their special relationship with the government, raises concerns about the potential for moral hazard and the problems that would arise if a housing GSE became financially distressed or insolvent. ; The discussion then focuses on two public policy debates that have been sparked by this special relationship. The first is whether the housing GSEs are efficient mechanisms for subsidizing housing. The second relates to the housing GSEs' safety and soundness and questions whether implicit guarantees of their liabilities are the best way to subsidize them.Government-sponsored enterprises ; Federal Home Loan Mortgage Corporation ; Federal National Mortgage Association ; Federal home loan banks

Arc guidance development work for tack-welded joints

DOWNSTREAM HEAT TRANSFER OF UPSTREAM MASS INJECTION IN SUPERSONIC LAMINAR BOUNDARY LAYER FLO

Automatic closed circuit television arc guidance control Patent

Automatic closed circuit television arc guidance control for welding joint

Closed circuit TV system automatically guides welding arc

Closed circuit television /CCTV/ system automatically guides a welding torch to position the welding arc accurately along weld seams. Digital counting and logic techniques incorporated in the control circuitry, ensure performance reliability