Analysis of Yield Spreads on Commercial Mortgage-Backed Securities

Yield spreads on commercial mortgage-backed securities (CMBS) are defined as the difference between the yield on CMBS and the yield on comparable-maturity Treasuries. CMBS yield spreads declined dramatically from 1992 until 1997, then increased in 1998 and 1999. The relationship between CMBS yield spreads and other variables is estimated in an effort to explain recent trends. Results identify several variables that are related to yield spreads on both fixed-rate and variable-rate CMBS. However, even after controlling for other observable factors, the yield spread on CMBS still declined from 1992 until 1997, then increased each of the next two years. Possible explanations for this phenomenon are explored.

CMBS Mortgage Pool Diversification and Yields: An Empirical Note: Working Paper Series--05-12

In the early years of the Commercial Mortgage-Backed Securities market, nearly all issues were backed by mortgages on a single property type. Beginning in the early 1990's, the composition of CMBS mortgage pools changed, and most mortgages on a variety of property types. This study examines the relationship between the diversification of the CMBS mortgage pool and yields on CMBS supported by the pool. Results indicate that yield spreads on AAA-rated CMBS backed by diversified pools are slightly lower than yield spreads on CMBS backed by undiversified pools. There is no evidence that yields on lower-rated CMBS are affected by pool diversification

Some Conceptual and Scaling Evaluations of Snowmelt Events Forced by Warm Soil

Snowfall occasionally occurs over bare soil with high thermal storage in its upper layer. Quantification and generalization of the potential impact of the thermal storage on episodic snowmelt is evaluated using a scaling approach and assuming negligible net thermal flux at the snow cover top. Soil thermal flux contribution to snowmelt is found to be affected significantly by the level of soil wetness. It is shown that, for a soil temperature of 10°C prior to the snowfall, the contribution of wet soil thermal flux is significant within the first 12 h when compared with intense surface moist enthalpy flux or solar radiation. Implications of these results to modeling of snowmelt using coupled soil–atmosphere models are elaborated

Development of Composite Sandwich Bonded Longitudinal Joints for Space Launch Vehicle Structures

The NASA Composite Technology for Exploration (CTE) Project is developing and demonstrating critical composite technologies with a focus on composite bonded joints; incorporating materials, design/analysis, manufacturing, and tests that utilize NASAs expertise and capabilities. The project has goals of advancing composite technologies and providing lightweight structures to support future NASA exploration missions. In particular, the CTE project will demonstrate weight-saving, performance-enhancing composite bonded joint technology for Space Launch System (SLS)-scale composite hardware. Advancements from the CTE project may be incorporated as future block upgrades for SLS structural components. This paper discusses the details of the development of a composite sandwich bonded longitudinal joint for a generic space launch vehicle structure called the CTE Point Design. The paper includes details of the design, analysis, materials, manufacturing, and testing of sub-element joint test articles to test the capability of the joint design. The test results show that the composite longitudinal bonded joint design significantly exceeds the design loads with a 2.0 factor of safety. Analysis pre-test failure predictions for all sub-element bonded joint test coupons were all within 10% of the average test coupon failure load. This testing and analysis provides confidence in the potential use of composite bonded joints for future launch vehicle structures