23:T4f6,

The influence of variations in solar activity on earth's surface temperature is a key question in climate-change attribution. On the basis of natural cyclic sea surface temperatures and the annual mean daily sunspot number as a proxy for variability in solar influence on the energy retained by the planet, a predictive equation derived from well-understood physical principles proves capable of reproducing observed anomalies in annual global mean surface temperature since before 1900 with 90% accuracy (R² = 0.9049). This accuracy results even where a zero-contribution from changes in greenhouse-gas concentrations is assumed. Here we show that the cumulative influence of the unusually elevated solar activity in the 64 years 1941–2005, as calculated using the time-integral of sunspot number anomalies (with a proxy factor) might have been a primary cause of the global warming observed through 2001. After 2001 the low solar activity is consistent with the observed flat average global temperature trend. The physically-based predictive equation, with the widely-projected decline in solar activity, moderated by the substantial effective thermal capacitance of the planet, especially the oceans, projects a downtrend steeper than 0.1K/decade.

24:T4aa,

A preliminary design tool was developed to optimize structures such as beams and plates, with optional cutouts, subject to multiple loadsets and any boundary conditions. SUNSPOT provides with simple, tapered and manufacturable layups.

Sublaminates, made of multiple plies at various orientations, combining one or more materials, are repeated or dropped in different zones of the structure, yielding the plydrops taper while ensuring physical continuity of the fibers in all composite layers.

The orientation and thickness of each ply group in this reference sublaminate as well as its number of repetitions in the zones across the structure, are optimized using the Nelder-Mead algorithm in conjunction with parametric SAMCEF Finite Element Analyses, all integrated within SUNSPOT.

The optimization objective is minimum weight for first ply failure strength. Maximum displacement constraints and economical manufacturing can be enforced additionally. Therefore, extended Tsai-Wu strength failure criteria were derived; new stiffness control criteria and a manufacturing complexity index were developed [1,2].

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Influence of Sunspots on Global Mean Surface Temperature

Design Optimization of Composite Plates: Part II—Structural Optimization by Plydrop Tapering