Design and Analysis of Remote Center of Compliance Structures

Remote center‐of‐compliance devices were developed to facilitate insertion for assembly operations. An analysis using screw theory yields a more accurate model to better characterize the interesting properties of remote compliance. For design purposes, the remote center location and stiffnesses are presented as nondimensional ratios that are only functions of geometrical properties and Poisson's ratio. Important design results are (i) the high sensitivity of the center location and (ii) the inverse relationship between linear and angular lateral stiffnesses. © 2003 Wiley Periodicals, Inc.     

A comparison of the dissolution of model compounds and the kerogen of Green River oil shale by oxidation with perchloric acid — A model for the kerogen of Green River oil shale

A stepwise degradation of a kerogen concentrate of Green River oil shale was effected by oxidation with perchloric acid of varying boiling point and concentration. Dissolution of the kerogen concentrate occurred between 160 and 170°C. Several model compounds were also oxidized with perchloric acid. The model compounds were polyethylene, graphite, nylon, and polyethylene oxide. The results indicated that the kerogen was similar to polyethylene oxide. The results of this study and previous work were used to present a model for the structure of the kerogen of Green River oil shale.     

Induced magnetic fields as evidence for subsurface oceans in Europa and Callisto

The Galileo spacecraft has been orbiting Jupiter since 7 December 1995, and encounters one of the four galilean satellites-Io, Europa, Ganymede and Callisto-on each orbit. Initial results from the spacecraft's magnetometer have indicated that neither Europa nor Callisto have an appreciable internal magnetic field, in contrast to Ganymede and possibly Io. Here we report perturbations of the external magnetic fields (associated with Jupiter's inner magnetosphere) in the vicinity of both Europa and Callisto. We interpret these perturbations as arising from induced magnetic fields, generated by the moons in response to the periodically varying plasma environment. Electromagnetic induction requires eddy currents to flow within the moons, and our calculations show that the most probable explanation is that there are layers of significant electrical conductivity just beneath the surfaces of both moons. We argue that these conducting layers may best be explained by the presence of salty liquid-water oceans, for which there is already indirect geological evidence in the case of Europa.     

Rule-based interpretation of aerial imagery

In this paper, we describe the organization of a rule-based system, SPAM, that uses map and domain-specific knowledge to interpret airport scenes. This research investigates the use of a rule-based system for the control of image processing and interpretation of results with respect to a world model, as well as the representation of the world model within an image/map database. We present results on the interpretation of a high-resolution airport scene wvhere the image segmentation has been performed by a human, and by a region-based image segmentation program. The results of the system's analysis is characterized by the labeling of individual regions in the image and the collection of these regions into consistent interpretations of the major components of an airport model. These interpretations are ranked on the basis of their overall spatial and structural consistency. Some evaluations based on the results from three evolutionary versions of SPAM are presented.     

A prological definition of HASL a purely functional language with unification based conditional binding expressions

We present a definition in Prolog of a new purely funtional (applicative) language HASL (HArvey’s StaticLanguage). HASL is a descendant of Turner’s SASL and differs from the latter in several significant points: it includes Abramson’s unification based conditional binding constructs; it restricts each clause in a definition of a HASL function to have the same arity, thereby complicating somewhat the compilation of clauses to combinators, but simplifying considerably the HASL reduction machine; and it includes the single element domain {fail} as a component of the domain of HASL data structures. It is intended to use HASL to express the functional dependencies in a translator writing system based on denotational semantics, and to study the feasibility of using HASL as a functional sublanguage of Prolog or some other logic programming language. Regarding this latter application we suggest that since a reduction mechanism exists for HASL, it may be easier to combine it with a logic programming language than it was for Robinson and Siebert to combine LISP and LOGIC into LOGLISP: in that case a fairly complex mechanism had to be invented to reduce uninterpreted LOGIC terms to LISP values. The definition is divided into four parts. The first part defines the lexical structure of the language by means of a simple Definite Clause Grammar which relates character strings to “token” strings. The second part defines the syntactic structure of the language by means of a more complex Definite Clause Grammar and relates token strings to a parse tree. The third part is semantic in nature and translates the parse tree definitions and expressions to a variable-free string of combinators and global names. The fourth part of the definition consists of a set of Prolog predicates which specifies how strings of combinators and global names are reduced to “values”, ie., integers, truth values, characters, lists, functions, fail, and has an operational flavour: one can think of this fourth part as the definition of a normal order reduction machine.     

Fungal products. Part XVII. Microbiological hydroxylation of gibberellin A9 and its methyl ester

Angiotensin II (A II) and analogues were tested for their ability to restore electrical and mechanical activity to cardiac muscle preparations in which the fast Na+ channels had been inactivated by partial depolarization (22-27 mM K+) or by tetrodotoxin (TTX). The partially depolarized or TTX-blocked preparations were chosen because under these conditions electrical and mechanical responses are primarily Ca2+ -dependent. In depolarized rabbit right atria, A II restored spontaneous mechanical and electrical activity (measured by both intracellular and extracellular recording techniques). The frequency of action potential discharge was concentration-dependent; the threshold concentration of A II was 10(-10) M, the ED50 was 8 X 10(-9) M, and the maximum effect was observed at 5 X 10(-8) M. In contrast, depolarized guinea pig atria were insensitive to A II, Sar1-angiotensin II, and des-Asp1-angiotensin II, even at concentrations as high as 10(-5) M. Rabbit papillary muscle (TTX-blocked), embryonic (18-day) chick heart (partially depolarized) and chick heart reaggregates (TTX-blocked) responded similarly to rabbit atria in that A II (9.6 X 10(-7) M) restored both electrical and mechanical activity. We found that in these preparations the action of A II was unaffected by propranolol (5.0 X 10(-6) M to 5.0 X 10(-5) M) but was blocked by Mn2+ (10(-3) M), D-600 (1 X 10(-7) g/ml) and the specific A II antagonists Sar1-Ala8-angiotensin II (P-113) (5.0 X 10(-5) M) and Sar1-Ile8-angiotensin II (5.28 X 10(-5) M). We conclude that the positive inotropic effect of A II on the myocardium is due to its ability to increase transmembrane ion movements in or through the cell membrane. The ability of Mn2+ and D-600 to block this effect suggests that this ion movement is via the so-called "slow channels."