Dynamic analysis of flexible multi-body systems using mixed modal and tangent coordinates

This paper presents a mixed modal and tangent coordinate technique for computer aided analysis of flexible mechanical systems whose components undergo large translations and large rotations. In this model the configuration of a flexible component is identified by using two sets of generalized coordinates, namely rigid body and elastic coordinates. The rigid body coordinates define the location and orientation of a body axis, whereas the elastic coordinates define the displacement field of a component with respect to its body axis. The elastic coordinates are introduced by using finite element discretization to model flexible components with complex geometries. A modal analysis technique is used to identify the elastic mode shapes and to eliminate insignificant higher frequency modes. An orthonormalization of constraint Jacobian matrix associated with rigid body coordinates is used to identify the rigid body tangent coordinates. The resulting modal and tangent coordinates are used to develop an automated numerical integration scheme to solve the system differential and algebraic equations. Two numerical examples are considered to show the feasibility of dynamic analysis of flexible mechanical systems using this scheme.     

Microstructure and Wear Characteristics of Al-4.5Cu-5Pb Alloy

Al-4.5Cu-5Pb alloy was prepared by sand and chill casting. The same alloy was also spray deposited at a gas pressure of 1.6 MPa. The microstructural features exhibit a coarse to fine dendritic morphology for sand and chill cast alloys. Equiaxed grains were observed for spray fOrmed alloys. Wear testing employing a pin-on-disc type set-up, reveaIs considerably lower wear of spray deposited alloy compared to that of chill and sand cast alloys. The morphological features of wear track on specimen and debris indicated a mixed oxidative-cum-adhesive wear mechanisms for these alloys tested in the present investigation     

Rare earth cobaltite catalysts: Relation of activity to spin and valence states of cobalt

Catalytic activities of rare earth cobaltites and related compounds are shown to be related to the spin and valence states of cobalt.     

Integrated nonuniform thin-film bandpass filter

A set of performance characteristics for a two-port three-terminal bandpass filter configuration of the integrated thin-film exponential distributed-parameter R-C-KR microsystem is presented. The circuit is found to have frequency response which is almost independent of the load. The bandpass filter requirements are shown to be achieved by a suitable combination of the parameters of the micro-system structure.     

The effect of central metal atom on the electrical properties of phthalocyanine macromolecule

In order to investigate the effect of the central metal atom variation on the electrical properties of phthalocyanine macromolecule, iron, cobalt, nickel and copper as the di-valent metals were incorporated into the macrocycle. The electrical properties of these metallophthalocyanines were then studied to establish a structure-property relation-ship. The experimental data show that electrical parameters are greatly influenced by the choice of metal atom. It remains to be investigated whether results are dominantly interpretable in terms of the size of the metal, intermolecular π-electron delocalization of the macrocycle, or other molecular orbital property.     

Fluid catalytic cracking: Selectivity and product yield patterns

Fluid catalytic cracking, a common secondary process employed in the petroleum industry, is used to convert heavier feedstocks into products such as liquefied Petroleum Gas (LPG), motor gasoline, diesel etc. The present study focuses on developing a three lump fraction kinetic model to estimate the yield of C5 up to 370°C cut (motor gasoline and middle distillates). A Micro Activity Test (MAT) apparatus was used to estimate the parameters in the kinetic model. The study is useful in evolving a procedure to simulate plant performance using experimental data obtained in the MAT apparatus for a particular catalyst and feedstock in terms of the product yield pattern.