High-frequency nonlinear vibrational control

This paper discusses the feasibility of high-frequency nonlinear vibrational control. Such control has the advantage that it does not require state measurement and processing capabilities that are required in conventional feedback control. Bellman et al. (1986) investigated nonlinear systems controlled by linear vibrational controllers and proved that vibrational control is not feasible if the Jacobian matrix has a positive trace. This paper extends previous work to include nonlinear vibrational controllers. A stability criteria is derived for nonlinear systems with nonlinear controllers, and it is shown that a nonlinear vibrational controller can stabilize a system even if the Jacobian matrix has a positive trace     

A parallel implementation of Flat Concurrent Prolog

Flat Concurrent Prolog is a simple, practical, concurrent programming language which has an efficient uniprocessor implementation. This paper describes an initial parallel implementation of the language; it consists of an interpreter implemented on an Intel iPSC Hypercube. The parallel execution of concurrent logic programming languages involves many nontrivial implementation problems. Some of these problems are well known and have been treated extensively in the literature. The most difficult task is to integrate problem solutions in a coherent and efficient manner. The algorithm presented has been useful in providing insights into the major problems and includes a number of novel ideas to simplify implementation. It does not attempt to solve all the problems involved but rather provides a workable basis for current and future research. The algorithm is under ongoing refinement, simplification and improvement.     

The prediction of the wild-type telomerase RNA pseudoknot structure and the pivotal role of the bulge in its formation

In this study, the three-dimensional structure of the wild-type human telomerase RNA pseudoknot was predicted via molecular modeling. The wild-type pseudoknot structure is then compared to the recent NMR solution structure of the telomerase pseudoknot, which does not contain the U177 bulge. The removal of the bulge from the pseudoknot structure results in higher stability and significant reduction of activity of telomerase. We show that the effect of the bulge on the structure results in a significant transformation of the pseudoknot junction region where the starting base pairs are disrupted and unique triple base pairs are formed. We found that the formation of the junction region is greatly influenced by interactions of the U177 bulge with loop residues and rotation of residue A174. Moreover, this is the first study to our knowledge where a structure as complex as the pseudoknot has been solved by purely theoretical methods.     

Query optimization for nontraditional database applications

Database query languages and their use for programming nontraditional applications, such as engineering and artificial intelligence applications, are discussed. In such environments, database programs are used to code applications that work over large data sets residing in databases. Optimizing such programs then becomes a necessity. An examination is made of various optimization techniques, and transformations are suggested for improving the performance of database programs. These transformations result in new equivalent database programs with better space and time performance. Several of these techniques apply to classical query languages, although extended query languages which include an iteration operator are specifically discussed     

Heuristics for rapidly four-coloring large planar graphs

We present several algorithms for rapidly four-coloring large planar graphs and discuss the results of extensive experimentation with over 140 graphs from two distinct classes of randomly generated instances having up to 128,000 vertices. Although the algorithms can potentially require exponential time, the observed running times of our more sophisticated algorithms are linear in the number of vertices over the range of sizes tested. The use of Kempe chaining and backtracking together with a fast heuristic which usually, but not always, resolves impasses gives us hybrid algorithms that: (1) successfully four-color all our test graphs, and (2) in practice run, on average, only twice as slow as the well-known, nonexact, simple to code, Θ(n) saturation algorithm of Brélaz.     

Computationalism

Computationalism, the notion that cognition is computation, is a working hypothesis of many AI researchers and Cognitive Scientists. Although it has not been proved, neither has it been disproved. In this paper, I give some refutations to some well-known alleged refutations of computationalism. My arguments have two themes: people are more limited than is often recognized in these debates; computer systems are more complicated than is often recognized in these debates. To underline the latter point, I sketch the design and abilities of a possible embodied computer system.     

Obtaining a high-density clinker based on natural dolomite and magnesite

Conclusions The main parameters for the production from natural dolomite and magnesite of high-density synthetic periclase-lime clinker containing 20% CaO have been determined under laboratory conditions.It is shown that this clinker may be obtained by firing at relatively low temperatures ( 1500°C) briquettes based on a hydrated mixture of previously decarbonated and milled dolomite and magnesite. This technology should make it possible to produce a material with a uniform distribution of components and an apparent density of 3.3 g/cm³.Translated from Ogneupory, No. 4, pp. 52–56, April, 1979.