ARTIFICIAL INTELLIGENCE 251 Learning and Executing Generalized Robot Plans I Recommended by D. Michie

In this paper we describe some major new additions to the STRIPS robot problem-solving system. The first addition is a process for generalizing a plan produced by SFRIPS so that problem-specific constants appearing in the plan are replaced by problem-independent para. meters. The genera!ized plan, stored m a convenient format called a triangle table, has two important functions. The more obvious function is as a single macro action that can be used by STRIPS--either in whole or in pt "t--durino the solution of a subsequent problem. Perhaps less obviously, the generalized plan also plays a central part in the process that monitors the real-world execution of a plan, and allows the robot to react "intelligently " to unexpected consequences of actions. We conclude with a discussion of experiments with the system on several example problems. 1

Nano-structural analysis of water distribution in hydrated multi-component gels using thermal and NMR relaxometry

Highly complex, multicomponent gels and water-containing soft materials have varied applications in biomedical, pharmaceutical, and food sciences, but the characterization of these nanostructured materials is extremely challenging. The aim of this study was to use stearoyl macrogol-32 glycerides (Gelucire 50/13) gels containing seven different species of glycerides, PEG, and PEG-esters, as model, complex, multicomponent gels, to investigate the effect of water content on the micro- and nanoarchitecture of the gel interior. Thermal analysis and NMR relaxometry were used to probe the thermal and diffusional behavior of water molecules within the gel network. For the highly concentrated gels (low water content), the water activity was significantly lowered due to entrapment in the dense gel network. For the gels with intermediate water content, multiple populations of water molecules with different thermal responses and diffusion behavior were detected, indicating the presence of water in different microenvironments. This correlated with the network architecture of the freeze-dried gels observed using SEM. For the gels with high water content, increased quantities of water with similar diffusion characteristics as free water could be detected, indicating the presence of large water pockets in these gels. The results of this study provide new insights into structure of Gelucire gels, which have not been reported before because of the complexity of the material. They also demonstrate that the combination of thermal analysis and NMR relaxometry offers insights into the structure of soft materials not available by the use of each technique alone. However, we also note that in some instances the results of these measurements are overinterpreted and we suggest limitations of the methods that must be considered when using them