Instantaneous Invariants in Three-Dimensional Kinematics

1978 ◽  
Vol 45 (2) ◽  
pp. 409-414 ◽  
Author(s):  
Y. Kirson ◽  
A. T. Yang
Keyword(s):  
Rigid Body ◽  
Rational Design ◽  
Three Dimensional ◽  
Higher Order ◽  
Surface Generation ◽  
Intrinsic Properties ◽  
Canonical Systems ◽  
Spatial Mechanisms ◽  
Arbitrary Line

The paper generalizes the concepts of canonical systems and instantaneous invariants from planar to three-dimensional kinematics. It presents a systematic procedure to determine the instantaneous invariants. An example is included for illustration. The instantaneous invariants are derived on the basis of line coordinates, therefore they are useful for the characterization of higher-order intrinsic properties of a ruled surface—the path trajectory of an arbitrary line embedded in a rigid body in three-dimensional motion. It is hoped that this study may be useful for the rational design of spatial mechanisms for surface generation.

On the Intrinsic Properties of Point Trajectories in Three-Dimensional Kinematics

1985 ◽  
Vol 107 (3) ◽  
pp. 401-405 ◽  
Author(s):  
L. M. Hsia ◽  
A. T. Yang
Keyword(s):  
Control Systems ◽  
Rational Design ◽  
Robot Manipulators ◽  
Three Dimensional ◽  
Intrinsic Properties ◽  
Spatial Mechanisms ◽  
Point Trajectories ◽  
Straight Lines ◽  
And Control ◽  
Analytical Expressions

In this paper we derive analytical expressions for curvature, torsion, and radius of osculating sphere of the point trajectory in three-dimensional kinematics. Corresponding to a design position we obtain equations of loci of points tracing straight lines, helical curves, and spherical curves. It is hoped that the result of this study will provide another step toward rational design of spatial mechanisms and control systems for robot manipulators.

The characterization of monadic logic

1973 ◽  
Vol 38 (3) ◽  
pp. 481-488 ◽  
Author(s):  
Leslie H. Tharp
Keyword(s):  
Finite Sequence ◽  
Higher Order ◽  
Predicate Calculus ◽  
Intrinsic Properties ◽  
Monadic Logic

The first section of this paper is concerned with the intrinsic properties of elementary monadic logic (EM), and characterizations in the spirit of Lindström [2] are given. His proofs do not apply to monadic logic since relations are used, and intrinsic properties of EM turn out to differ in certain ways from those of the elementary logic of relations (i.e., the predicate calculus), which we shall call EL. In the second section we investigate connections between higher-order monadic and polyadic logics.EM is the subsystem of EL which results by the restriction to one-place predicate letters. We omit constants (for simplicity) but take EM to contain identity. Let a type be any finite sequence (possibly empty) of one-place predicate letters. A model M of type has a nonempty universe ∣M∣ and assigns to each predicate letter P of a subset PM of ∣M∣.Let us take a monadic logic L to be any collection of classes of models, called L-classes, satisfying the following:1. All models in a given L-class are of the same type (called the type of the class).2. Isomorphic models lie in the same L-classes.3. If and are L-classes of the same type, then and are L-classes.

scholarly journals Nonlinear interactions in deformable container cranes

2015 ◽  
Vol 230 (1) ◽  
pp. 5-20 ◽  
Author(s):  
Andrea Arena ◽  
Walter Lacarbonara ◽  
Matthew P Cartmell
Keyword(s):  
Rigid Body ◽  
Internal Resonance ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Higher Order ◽  
Mode Shapes ◽  
Lagrange Equations ◽  
Internal Resonances ◽  
Container Cranes ◽  
Bending Mode

Nonlinear dynamic interactions in harbour quayside cranes due to a two-to-one internal resonance between the lowest bending mode of the deformable boom and the in-plane pendular mode of the container are investigated. To this end, a three-dimensional model of container cranes accounting for the elastic interaction between the crane boom and the container dynamics is proposed. The container is modelled as a three-dimensional rigid body elastically suspended through hoisting cables from the trolley moving along the crane boom modelled as an Euler-Bernoulli beam. The reduced governing equations of motion are obtained through the Euler-Lagrange equations employing the boom kinetic and stored energies, derived via a Galerkin discretisation based on the mode shapes of the two-span crane boom used as trial functions, and the kinetic and stored energies of the rigid body container and the elastic hoisting cables. First, conditions for the onset of internal resonances between the boom and the container are found. A higher order perturbation treatment of the Taylor expanded equations of motion in the neighbourhood of a two-to-one internal resonance between the lowest boom bending mode and the lowest pendular mode of the container is carried out. Continuation of the fixed points of the modulation equations together with stability analysis yields a rich bifurcation behaviour, which features Hopf bifurcations. It is shown that consideration of higher order terms (cubic nonlinearities) beyond the quadratic geometric and inertia nonlinearities breaks the symmetry of the bifurcation equations, shifts the bifurcation points and the stability ranges, and leads to bifurcations not predicted by the low order analysis.

scholarly journals Molecular details of sugar biosynthesis in mycobacteria

2014 ◽  
Vol 70 (a1) ◽  
pp. C1659-C1659
Author(s):  
Joana Fraga ◽  
Alexandra Silva ◽  
Ana Maranha ◽  
Vitor Mendes ◽  
Susana Alarico ◽  
...  
Keyword(s):  
Cell Wall ◽  
Structural Characterization ◽  
Rational Design ◽  
Three Dimensional ◽  
Molecular Targets ◽  
Molecular Models ◽  
Multiple Drugs ◽  
Drug Leads ◽  
Wall Components

Despite the research efforts of decades, Mycobacterium tuberculosis is still in the origin of 1.3 million deaths annually (WHO, Tuberculosis, 2013) and is estimated to infect 2 billion people worldwide. The currently available antimicrobial therapies are aimed at only a few molecular targets and the growing number of strains resistant to multiple drugs drives an urgent need for the identification of novel pathways and new points for therapeutic intervention. Although the sequence of the M. tuberculosis genome has been known for more than a decade, there is still no function assigned to many of its genes. Among M. tuberculosis ORFs with known function, more than 1% encode enzymes involved in glycosidic bond synthesis. Since the increased resilience of M. tuberculosis is, to a great extent, due to its complex, polysaccharide/lipid-rich and thus unusually impermeable cell wall, we became interested on the functional and structural characterization of mycobacterial enzymes involved in biosynthetic pathways for cell wall components. Over the last few years, we have carried out the functional and structural characterization of novel enzymes in the sugar biosynthesis metabolic routes from thermostable and mesostable mycobacteria [1-3]. Recently, we characterized functionally two enzymes from M. vanbalenii and M. hassiacum whose orthologs in M. tuberculosis are essential for growth, and determined their three-dimensional structures to high resolution (1.2-1.5 Å), allowing the thorough elucidation of their intricate nucleotide and sugar specificities. These experimental molecular models will be presented as examples of frameworks for the rational design of novel anti-mycobacterial drug leads. (Funded by national funds through FCT and by EU-FEDER funding through COMPETE (grants FCOMP-01-0124-FEDER-014321, FCOMP-01-0124-FEDER-014187, FCOMP-01-0124-FEDER-028359) and through ON.2-O Novo Norte, under QREN (grant NORTE-07-0124-000002 - Host-Pathogen Interactions).

On the Principle of Transference In Three-Dimensional Kinematics

1981 ◽  
Vol 103 (3) ◽  
pp. 652-656 ◽  
Author(s):  
L. M. Hsia ◽  
A. T. Yang
Keyword(s):  
Rigid Body ◽  
Three Dimensional ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Intrinsic Properties ◽  
Numerical Examples ◽  
Systematic Procedure ◽  
Point Trajectories

In this paper, the principle of transference is developed and applied to the establishment of a systematic procedure for the determination, via screw calculus, of a prescribed rigid body motion. This is an essential first step toward the study of the intrinsic properties of point trajectories in three-dimensional kinematics. Two numerical examples are presented for illustrative purposes.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

Characterization of a monolayer graphitic structure

1994 ◽  
Vol 52 ◽  
pp. 760-761
Author(s):  
X. Lin ◽  
X. K. Wang ◽  
V. P. Dravid ◽  
J. B. Ketterson ◽  
R. P. H. Chang
Keyword(s):  
Three Dimensional ◽  
Single Layer ◽  
Synthesis Process ◽  
Graphitic Structure ◽  
Positive Gaussian Curvature ◽  
Graphitic Sheet ◽  
Structural And Electronic Properties ◽  
New Material ◽  
Hexagonal Network

For small curvatures of a graphitic sheet, carbon atoms can maintain their preferred sp2 bonding while allowing the sheet to have various three-dimensional geometries, which may have exotic structural and electronic properties. In addition the fivefold rings will lead to a positive Gaussian curvature in the hexagonal network, and the sevenfold rings cause a negative one. By combining these sevenfold and fivefold rings with sixfold rings, it is possible to construct complicated carbon sp2 networks. Because it is much easier to introduce pentagons and heptagons into the single-layer hexagonal network than into the multilayer network, the complicated morphologies would be more common in the single-layer graphite structures. In this contribution, we report the observation and characterization of a new material of monolayer graphitic structure by electron diffraction, HREM, EELS.The synthesis process used in this study is reported early. We utilized a composite anode of graphite and copper for arc evaporation in helium.

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