Total solar irradiance measurements from the 1984‐1993 Earth Radiation Budget Satellite (ERBS) active cavity radiometer and 1978‐1993 Nimbus 7 transfer cavity radiometer spacecraft experiments are analyzed to detect the presences of 11‐, 22‐, and 80‐year irradiance variability components. The analyses confirmed the existence of a significant 11‐year irradiance variability component, associated with solar magnetic activity and the sunspot cycle. The analyses also suggest the presence of a 22‐ or 80‐year variability component. The earlier Nimbus 7 and Solar Maximum Mission (SMM) spacecraft irradiance measurements decreased approximately 1.2 and 1.3 Wm−2, respectively, between 1980 and 1986. The Nimbus 7 values increased 1.2 Wm−2 between 1986 and 1989. The ERBS irradiance measurements increased 1.3 Wm−2 during 1986‐1989, and then decreased 0.4 Wm−2 (at an annual rate of 0.14 Wm−2yr−1) during 1990‐1993. Considering the correlations between ERBS, Nimbus 7, and SMM irradiance trends and solar magnetic activity, the total solar irradiance should decrease to minimum levels by 1997 as solar activity decreases to minimum levels, and then increase to maximum levels by the year 2000 as solar activity rises. The ERBS measurements yielded 1365.4 ± 0.7 Wm−2 as the mean irradiance value with measurement accuracies and precisions of 0.2% and 0.02%, respectively. The ERBS mean irradiance value is within 0.2% of the 1367.4, 1365.9, and 1366.9 Wm−2 mean values for the SMM, Upper Atmosphere Research Satellite (UARS), and Space Shuttle Atmospheric Laboratory for Applications and Science (ATLAS 1) Solar Constant (SOLCON) active cavity radiometer spacecraft experiments, respectively. The Nimbus 7 measurements yielded 1372.1 Wm−2 as the mean value with a measurement accuracy of 0.5%. Empirical irradiance model fits, based upon 10.7‐cm solar radio flux (F10) and photometric sunspot index (PSI), were used to assess the quality of the ERBS, Nimbus 7, SMM, and the UARS irradiance data sets and to identify irradiance variability trends which may be caused by drifts or shifts in the spacecraft sensor responses. Comparisons among the fits and measured irradiances indicate that the Nimbus 7 radiometer response shifted by a total of 0.8 Wm−2 between September 1989 and April 1990 and that the ERBS and UARS radiometers each drifted approximately 0.5 Wm−2 during the first 5 months in orbit.

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a b s t r a c tGrain boundary embrittlement occurs when a solute enriches at a grain boundary and lowers its cohesive energy. While grain boundary enrichment is often attributed to equilibrium segregation effects, most models of embrittlement consider either the energetics of decohesion or the equilibrium adsorption at the boundary, but not both phenomena together. We develop a model for the change in cohesive energy of a grain boundary of a pure metal upon introduction of solute under conditions of equilibrium segregation prior to fracture. A heuristic grain boundary cohesion map is presented to delineate whether a given solute-solvent pair will exhibit weakening or strengthening of grain boundaries. The analysis helps to clarify that grain boundary embrittlement requires a solute that will both lower the cohesive energy of the boundary and segregate in the first place. The map reasonably captures known metal-metal embrittling pairs.

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Silicon based quadrupole mass spectrometry using microelectromechanical systemsReal-time feedback control of semiconductor processes based on in situ sensors can complement present statistical process control techniques. In this article, we explore the potential of quadrupole mass spectrometry as an in situ sensing technique. We show that it is possible to sense the fluxes of important species in a plasma process and use these measurements to implement a multivariable control scheme. As an example, the control of hydrogen, unreacted ammonia, and direct current bias in a plasma enhanced chemical vapor deposition silicon nitride process is demonstrated.