Rensselaer Polytechnic Institute

About: Rensselaer Polytechnic Institute is a education organization based out in Troy, New York, United States. It is known for research contribution in the topics: Terahertz radiation & Population. The organization has 19024 authors who have published 39922 publications receiving 1414699 citations. The organization is also known as: RPI & Rensselaer Institute.

On transformation strains and uniform fields in multiphase elastic media

Abstract: The effect of local eigenstrain and eigenstress fields, or transformation fields, on the local strains and stresses is explored in multiphase elastic solids of arbitrary geometry and material symmetry. The residual local fields caused by such transformation fields are sought in terms of certain transformation influence functions and transformation concentration factor tensors. General properties of these functions and concentration factors, and their relation to the analogous mechanical influence functions and concentration factors, are established, in part, with the help of uniform strain fields in multiphase media. Specific estimates of the transformation concentration factor tensors are evaluated by the self-consistent and Mori-Tanaka methods. It is found here that although the two methods use different constraint tensors in solutions of the respective dilute problems, their estimates of the mechanical, thermal, and transformation concentration factor tensors, and of the overall stiffness of multiphase media have a similar structure. Proofs that guarantee that these methods comply with the general properties of the transformation influence functions, and provide diagonally symmetric estimates of the overall elastic stiffness, are given for two-phase and multiphase systems consisting of, or reinforced by, inclusions of similar shape and alignment. One of the possible applications of the results, in analysis of overall instantaneous properties and local fields in inelastic composite materials, is described in the following paper.

Multilevel interconnections for ULSI and GSI era

Abstract: A high performance interconnection network on a chip is essential to match the ever improving performance of the semiconductor devices they interconnect. This issue reviews the need, some fundamental background justifying the need, approaches one can take in trying to satisfy the need, and associated issues related to the concept of multilevel interconnection (MLI) technology for the ULSI/GSI era of the silicon integrated circuits, with emphasis on materials and the processes that will lead to an acceptable MLI scheme. Thus besides discussing the MLI concepts and implementation issues, properties of metals and their alloys (especially those of Cu and Al), diffusion barrier/adhesion promoter, interlayer dielectrics, deposition and etching of mateials, planarization issues, reliability issues, and new materials concepts are presented. Emphasis is obviously placed on the presently focused research on replacing aluminum with copper based interconnections. The author's viewpoint on gradual changes in replacing current materials with newer mateials as they become available is also presented. A synergism between the materials sets for on-chip and off-chip interconnections has been pointed out.

Assessing the Impact of Management Buyouts on Economic Efficiency: Plant-Level Evidence from the United Kingdom

Abstract: We assess the total factor productivity of 35,752 manufacturing establishments before and after management buyouts (MBOs). MBO plants are less productive than comparable plants before the transfer of ownership. They experience a substantial increase in productivity after a buyout, which appears to be due to measures undertaken by new owners to reduce the labor intensity of production, via outsourcing of intermediate goods and materials. These findings, which are pervasive across industries, imply that MBOs reduce agency costs and enhance economic efficiency. Our evidence is consistent with Jovanovic and Rousseau (2002), who suggest that ownership changes shift resources to more efficient uses and to better managers.

Dendritic growth-A test of theory

Abstract: Steady-state theories of dendritic solidification are reviewed, and three nonisothermal theories, expressed as simple power laws, are chosen for experimental verification. Specifically, the axial growth rate,V, of a freely growing dendrite can be expressed asV =βGΔθn, wheren andβ are the exponent and prefactor derived from each theory,G is a lumped material parameter, andΔθ is the supercooling. Succinonitrile, a low entropy-of-fusion plastic crystal, was prepared in several states of purity as the test system, and dendritic growth was studied both in the usual manner in long tubes, and in a novel apparatus in which the conditions for “free” dendritic growth were attained. Kinetic measurements show that only when “free” growth conditions obtain are the data reconcilable with current theory in the form discussed above. In particular, we show thatn = 2.6, in agreement with the theories of Nash and Glicksman and that of Trivedi; however, the prefactorsβ of those theories do not agree with the value determined for succinonitrile, which is the only substance for whichG is known accurately. Tip radius measurements, taken over a relatively narrow range of supercooling, when combined with the growth rate data prove that the Peclet number-supercooling relationship derived for each of the three nonisothermal steady-state theoriesall agree with experiment. This curious agreement, along with the inability to “decompose” the Peclet numbers into acceptable velocity-supercooling and tip radius-supercooling relationships is explained on the basis of the limitations imposed by the steady-state assumption itself. Directions for future theoretical and experimental investigation are discussed in the light of the findings presented.

Ethnography in Late Industrialism

Abstract: This essay situates contemporary ethnography within late industrialism, a historical period characterized by degraded infrastructure, exhausted paradigms, and the incessant chatter of new media. In the spirit of Writing Culture, it calls for ethnography attuned to its times. It also calls for ethnography that “loops,” using ethnographic techniques to discern the discursive risks and gaps of a particular problem domain so that further ethnographic engagement in that domain is responsive and creative, provoking new articulations, attending to emergent realities. Ethnographic findings are thus fed back into ethnographic engagement. This mode of ethnography stages collaboration with interlocutors to activate new idioms and ways of engaging the world. It is activist, in a manner open to futures that cannot yet be imagined.