Clasts in the CM2 carbonaceous chondrite Lonewolf Nunataks 94101: evidence for aqueous alteration prior to complex mixing

Clasts in the CM2 carbonaceous chondrite Lonewolf Nunataks (LON) 94101 have been characterized using scanning and transmission electron microscopy and electron microprobe analysis to determine their degrees of aqueous alteration, and the timing of alteration relative to incorporation of clasts into the host. The provenance of the clasts, and the mechanism by which they were incorporated and mixed with their host material are also considered. Results show that at least five distinct types of clasts occur in LON 94101, of which four have been aqueously altered to various degrees and one is largely anhydrous. The fact that they have had different alteration histories implies that the main part of aqueous activity occurred prior to the mixing and assimilation of the clasts with their host. Further, the presence of such a variety of clasts suggests complex mixing in a dynamic environment involving material from various sources. Two of the clasts, one containing approximately 46 vol% carbonate and the other featuring crystals of pyrrhotite up to approximately 1 mm in size, are examples of unusual lithologies and indicate concentration of chemical elements in discrete areas of the parent body(ies), possibly by flow of aqueous solutions

Spatially Dependent Parameter Estimation and Nonlinear Data Assimilation by Autosynchronization of a System of Partial Differential Equations

Given multiple images that describe chaotic reaction-diffusion dynamics, parameters of a PDE model are estimated using autosynchronization, where parameters are controlled by synchronization of the model to the observed data. A two-component system of predator-prey reaction-diffusion PDEs is used with spatially dependent parameters to benchmark the methods described. Applications to modelling the ecological habitat of marine plankton blooms by nonlinear data assimilation through remote sensing is discussed

GPPL: A Small Block-Structured Imperative Programming Language Implemented Using Ox

GPPL is a small, block-structured, imperative programming language, for which a compiler, gc, has been built using the Yacc/Lex-based attribute-grammar compiler Ox (see TR#92-30). This paper describes GPPL and gc, and is directed mainly to those who would like to study and modify them. The implementation of GPPL may be considered as an example of the use of attribute grammars in general and as a nontrivial example application of Ox. The syntax of GPPL bears some resemblance to that of C but, being described in only about eighty grammar rules, lacks many C constructs. GPPL\u27s semantics are similar to those of Pascal, with block structure and relatively strict error checking. gc\u27s target language is a very small subset of C. The source code for gc occupies about seventy kilobytes and constitutes about a dozen files. This paper describes GPPL syntax and semantics, gives some example programs, and explains the implementation with reference to the source code, which is included

User Manual for Ox: An Attribute-Grammar Compiling System based on Yacc, Lex, and C

Ox generalizes the function of Yacc in the way that attribute grammars generalize context-free grammars. Ordinary Yacc and Lex specifications may be augmented with definitions of synthesized and inherited attributes written in C syntax. From these specifications, Ox generates a program that builds and decorates attributed parse trees. Ox accepts a most general class of attribute grammars. The user may specify postdecoration traversals for easy ordering of side effects such as code generation. Ox handles the tedious and error-prone details of writing code for parse-tree management, so its use eases problems of security and maintainability associated with that aspect of translator development. The translators generated by Ox use internal memory management that is often much faster than the common technique of calling malloc once for each parse-tree node. Ox is a Yacc/Lex/C preprocessor, and is designed to bring attribute grammars closer to the mainstream of Unix-based language development. Ox inherits all of the familiar syntax and semantics of Yacc, Lex, and C. It is relatively easy to convert programs between Ox code and pure Yacc/Lex/C code. Ox has been used to build a compiler for a small (eighty grammar rules) block-structured imperative programming language. This document is the main reference for using Ox

Design, Implementation, Use, and Evaluation of Ox: An Attribute- Grammar Compiling System based on Yacc, Lex, and C

Ox generalizes the function of Yacc in the way that attribute grammars generalize context-free grammars. Ordinary Yacc and Lex specifications may be augmented with definitions of synthesized and inherited attributes written in C syntax. From these specifications, Ox generates a program that builds and decorates attributed parse trees. Ox accepts a most general class of attribute grammars. The user may specify postdecoration traversals for easy ordering of side effects such as code generation. Ox handles the tedious and error-prone details of writing code for parse-tree management, so its use eases problems of security and maintainability associated with that aspect of translator development. The translators generated by Ox use internal memory management that is often much faster than the common technique of calling malloc once for each parse-tree node. Ox is a Yacc/Lex/C preprocessor, and is designed to bring attribute grammars closer to the mainstream of Unix-based language development. Ox inherits all of the familiar syntax and semantics of Yacc, Lex, and C. It is relatively easy to convert programs between Ox code and pure Yacc/Lex/C code. Ox has been used to build a compiler for a small (eighty grammar rules) block-structured imperative programming language. This paper considers Ox\u27s design, implementation, and use, evaluates the performance of Ox-generated evaluators, and makes recommendations for improvements in Ox