Showing papers by "Rensselaer Polytechnic Institute published in 1985"
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TL;DR: In this paper, Johnson has added two new chapters on the Internet: one focusing on ethical behavior online, and the other addressing the social implications of the Internet, and they are presented in compelling and understandable language so that rigorous, in-depth analysis is accessible to students who may be novices in philosophy or technology studies.
Abstract: From the Publisher:
Author Deborah G. Johnson has updated material throughout this text. Two new chapters on the Internet have been added: one focuses on ethical behavior online, and the other addresses the social implications of the Internet.
Topics covered include:
What is computer ethics?
What are the philosophical foundations of computer ethics?
How does computer ethics relate to professional ethics?
Privacy.
Property rights.
Accountability.
All topics are presented in compelling and understandable language, so that rigorous, in-depth analysis is accessible to students who may be novices in philosophy or technology studies.
534 citations
25 Mar 1985
TL;DR: Two algorithms which use partial octree models to determine the "best" next view to take to obtain a complete model of a scene are described.
Abstract: There are situations in which one would like to know a good sequence of range-image views for obtaining a complete model of a scene. This paper describes two algorithms which use partial octree models to determine the "best" next view to take.
445 citations
TL;DR: In this paper, the authors combined the use of a linear (dc) power flow transmission model and a transportation model (also known as a trans-shipment model) for long range transmission planning, where new load growth, new generation sites and perhaps a new voltage level are to be considered.
Abstract: In long range transmission planning, where new load growth, new generation sites and perhaps a new voltage level are to be considered, a computer aided method of visualizing new circuits in a network context is needed. The new method presented meets this need by the combined use of a linear (dc) power flow transmission model and a transportation model (also known as a trans-shipment model). The dc transmission model is solved for the facilities network by obeying both of Kirchhoff's laws, flow conservation at each bus and voltage conservation around each loop. The transportation model is solved for the overloads by obeying only the bus flow conservation law while minimizing a cost objective function.
293 citations
TL;DR: In this article, the authors prove global stability for a simple adaptive algorithm that can use low-order model reference and controllers, since no observers or identifiers are used in the adaptation process.
Abstract: Most self-tuning and adaptive control algorithms usually use reference models, controllers, or identifiers of about the same order as the controlled plant. Since the dimension of the plants in the real world may be very large or unknown, implementation of adaptive control procedures may be difficult, or sometimes impossible. In this paper we prove global stability for a simple adaptive algorithm that can use low-order model reference and controllers, since no observers or identifiers are used in the adaptation process. The algorithm is basically fitted for systems that are denominated as ‘almost positive real’. It is shown that, at the price of bounded rather than vanishing output tracking errors, the simple algorithm can be applied in systems that can be stabilized via constant output feedback. These procedures are believed to reduce considerably the effort required for implementation of adaptive control in practical applications, especially in multivariable large-scale systems.
194 citations
TL;DR: In this paper, the authors evaluated stiffnesses and compliances, thermal expansion coefficients, and stress and strain averages for a fibrous composite lamina which contains a given density of open transverse cracks and is subjected to uniform mechanical loads and thermal changes.
Abstract: Overall stiffnesses and compliances, thermal expansion coefficients, and stress and strain averages are evaluated for a fibrous composite lamina which contains a given density of open transverse cracks and is subjected to uniform mechanical loads and thermal changes. The evaluation procedure is based on the self-consistent method and is similar, in principle, to that used in finding elastic constants of unidirectional com posites.
193 citations
TL;DR: In this paper, a control volume-based finite element method for solving the Navier-Stokes equations using equal-order velocity-pressure interpolation is presented, which calculates velocity and pressure at all the grid points in the domain.
Abstract: A control volume-based finite-element method for solving the Navier-Stokes equations using equal-order velocity-pressure interpolation is presented. Unlike the unequal-order-type methods that compute pressure at much fewer grid points than velocity, the proposed equal-order method calculates velocity and pressure at all the grid points in the domain. The validity of the method is established by applying it to solve some test problems
172 citations
TL;DR: In this article, the glass transition behavior of non-crystalline poly(oxymetheylene) poly(oxymethylene) is discussed and heat capacity data of semicrystalline samples are analyzed.
Abstract: Heat capacity data of semicrystalline poly(oxymethylene) samples. Delrin and Celcon, are analysed in order to discuss the glass transition behaviour of this polymer. There are two types of non-crystalline poly(oxymetheylene). the mobile and rigid amorphous parts. The glass transition of the former occurs in a rather wider range of temperature: it starts at 180 K and could end at 265 K. The latter, under restraint due to the crystallites, remains frozen up to the melting temperature.
167 citations
TL;DR: In this article, a series of experiments, four crystallization and four partial melting, were performed at 1000°C and 10 kilobars in the quartz-alkali feldspar-granitic melt system in order to determine the equilibrium melt distribution and textural adjustment processes.
161 citations
TL;DR: In this paper, the beam theory derived from variational principles is based on the sole kinematic assumption that each section is infinitely rigid in its own plane, but free to warp out of plane.
Abstract: Beam theory plays an important role in structural analysis. The basic assumption is that initially plane sections remain plane after deformation, neglecting out-of-plane warpings. Predictions based on these assumptions are accurate for slender, solid, cross-sectional beams made out of isotropic materials. The beam theory derived in this paper from variational principles is based on the sole kinematic assumption that each section is infinitely rigid in its own plane, but free to warp out of plane. After a short review of the Bernoulli and Saint-Venant approaches to beam theory, a set of orthonormal eigenwarpings is derived. Improved solutions can be obtained by expanding the axial displacements or axial stress distribution in series of eigenwarpings and using energy principles to derive the governing equations. The improved Saint-Venant approach leads to fast converging solutions and accurate results are obtained considering only a few eigenwarping terms.
156 citations
TL;DR: Evidence that cultivars of manioc (Manihot esculenta) have been selected for combinations of characters that allow them to be perceptually distinguished is presented and Anthropological evidence is presented to demonstrate that Aguaruna interact with the plants as predicted by the model.
Abstract: This paper presents evidence that cultivars of manioc (Manihot esculenta) have been selected for combinations of characters that allow them to be perceptually distinguished. This mode of selection is proposed to explain why cultivars are so variable in perceptually salient taxonomic characters unrelated to the use or survival of the plant. This paper reanalyzes published material on manioc and related species and presents new evidence from the inventory of manioc cultivars maintained by the Aguaruna Jivaro of northern Peru. Rogers and Fleming’s (1973) sample of manioc cultivars exhibits 3 characteristics implied by the model of selection for perceptual distinctiveness: high, continuous, and independent variation of nonadaptive taxonomic characters. The inventory of Aguaruna cultivars exhibits 2 additional characteristics predicted by the model: taxonomic characters of this local inventory vary as independently and nearly as greatly as those of the species as a whole. Anthropological evidence is presented to demonstrate that Aguaruna interact with the plants as predicted by the model: Aguaruna identify cultivars using many of the same characters as Rogers and Fleming and they confuse cultivars they regard as similar in stem color, petiole color, and leaf shape. The evidence suggests that procedures used by cultivators to identify cultivars leave their imprint on the plants; crops show the effect of the cultivator's eye as well as hand.
156 citations
TL;DR: The combination of programming the period of putative conditioning to be shortly after injections and using rats habituated to drinking ETOH allowed a conditioned place preference to emerge after only a few conditioning trials, which potentially reveals features of the way EOF achieves its reinforcing capability and sets the stage for understanding the mechanism of that reinforcement.
Abstract: Rats that had previously consumed a 6% ethanol (ETOH) solution daily for 26 days and rats without such a history served as subjects in a test for the ability of ETOH to establish a conditioned place preference. The time of putative conditioning was from 4 to 8 min after injections of ETOH, 1 g/kg. The combination of programming the period of putative conditioning to be shortly after injections and using rats habituated to drinking ETOH allowed a conditioned place preference to emerge after only a few conditioning trials. Such a result potentially reveals features of the way ETOH achieves its reinforcing capability and sets the stage for understanding the mechanism of that reinforcement.
TL;DR: In this article, the authors pointed out possible pitfalls and errors in the measurement of haze by ASTM Method D 1003 and discussed the advantages of obtaining both spectrophotometric and goniophotometric data for the characterization and interpretation of haze.
Abstract: Possible pitfalls and errors in the measurement of haze by ASTM Method D 1003 are pointed out and discussed. This property is an important measure of the optical clarity of plastic films and sheets. Although special hazemeters are usually used for the measurement, it is demonstrated that accurate haze measurements can be performed by using widely available integrating-sphere spectrophotometers. Additional advantages of obtaining both spectrophotometric and goniophotometric data for the characterization and interpretation of haze are pointed out.
TL;DR: In this article, the diffusion coefficients for Sm, Sr, and Pb in fluorapatite at 900°-1250°C were obtained by measuring experimentally-induced diffusional uptake profiles of these elements in the margins of gem-quality apatite crystals.
TL;DR: A simulation of the organic layer accreted onto interstellar dust particles was prepared by slow deposition of a CO:NH3:H2O gas mixture on an Al block at 10K, with concomitant irradiation with vacuum UV.
Abstract: The interstellar grains are currently considered to be the basic building blocks of comets and, possibly, meteorites. To test this theory, a simulation of the organic layer accreted onto interstellar dust particles was prepared by slow deposition of a CO:NH3:H2O gas mixture on an Al block at 10 K, with concomitant irradiation with vacuum UV. The results of the HPLC and IR analyses of the nonvolatile residue formed by photolysis at 10 K are compared with those observed at 77 K and 298 K. Some of the compounds that may be present on the surfaces of interstellar dust particles have been identified, and some specific predictions concerning the types of molecular species present in comets could be drawn. The results also suggest that photochemical reactions may have been important for the formation of meteorite components. The implication of the findings to the questions of the source of organic matter on earth and the origin of life are discussed.
TL;DR: In this paper, the authors considered irrotational transient free surface flow past a bump and showed that for Froude numbers sufficiently close to 1, the transient flow begins by satisfying the classical linear theory and grows with time to become nonlinear then satisfying the Korteweg-de Vries (KdV) equation with a forcing term.
TL;DR: In this article, the heat capacities of poly(oxymethylene) and poly(oxyethylene)-s were determined by differential scanning calorimetry from 205 K through the melting transition.
Abstract: The heat capacities of 38 semicrystalline poly(oxymethylene)s and poly(oxyethylene)s were determined by differential scanning calorimetry from 205 K through the melting transition. By comparison with the well known limiting heat capacities of the supercooled liquids and the crystals of the macromolecules it was found that there are negative and positive deviations from additivity of the heat capacities with crystallinity between the glass transition and the melting transition. The negative deviations are linked with “rigid amorphous” material, and the positive deviations were previously linked to defect formation or early melting. The rigid amorphous fraction in poly(oxymethylene) is constant up to the melting region, in contrast to polypropylene, where it is decreasing with temperature. The proposed mesophase transition in poly(oxymethylene) is shown to be a minor effect. The poly(oxyethylene) heat capacity is governed by positive heat capacity deviations within the rather short temperature range between glass transition and melting.
TL;DR: In this article, it was shown that the onset of turbulence is delayed from 2100 to about 4000 Reynolds number for flow in porous tubes with suction when compared to flow in non-porous tubes.
TL;DR: Simulations on real images show significant improvement over the conventional DPCM and tree codes using these new techniques, and the strong robustness property of these coding schemes is also experimentally demonstrated.
Abstract: The purpose of this paper is to present new image coding schemes based on a predictive vector quantization (PVQ) approach. The predictive part of the encoder is used to partially remove redundancy, and the VQ part further removes the residual redundancy and selects good quantization levels for the global waveform. Two implementations of this coding approach have been devised, namely, sliding block PVQ and block tree PVQ. Simulations on real images show significant improvement over the conventional DPCM and tree codes using these new techniques. The strong robustness property of these coding schemes is also experimentally demonstrated.
TL;DR: Coatings for high temperature applications as mentioned in this paper, Coatings for HV applications, Coatings in HV application, High Temperature Application, HV Application, High temperature applications.
Abstract: Coatings for high temperature applications , Coatings for high temperature applications , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
TL;DR: It is shown that when the utility function is linear or exponential (constant risk averseness), permanent preferences prevail and an efficient Dijkstra-type algorithm can be used.
Abstract: The classical shortest route problem in networks assumes deterministic link weights, and route evaluation by a utility (or cost) function that is linear over path weights. When the environment is stochastic and the “traveler’s” utility function for travel attributes is nonlinear, we define “optimal paths” that maximize the expected utility. In this setting, the concept of temporary and permanent preferences for route choices is introduced. It is shown that when the utility function is linear or exponential (constant risk averseness), permanent preferences prevail and an efficient Dijkstra-type algorithm can be used.
TL;DR: In this article, a unified approach based on the full solution to the so-called ordinary Langevin equation of motion is presented to study particle deposition on a single spherical collector, where the inertial, external, and particle-particle interaction forces are comparable to the diffusive, or Brownian, force.
TL;DR: In this article, an experimental study was conducted to verify the hypothesis that Ni3Al, which exhibits an L1(2) structure and remains ordered up to the melting point, would be severely embrittled by hydrogen and that this effect would be reversible.
TL;DR: Simple, but accurate, asymptotic approximations are derived for the deformation and stress fields in the tissue for slow and moderately fast rates of compression and lead to important insights into the role of the flow-dependent viscoelastic nature of articular cartilage and other hydrated biological tissues.
Abstract: The dominant mechanism giving rise to the viscoelastic response of articular cartilage during compression is the nonlinear diffusive interaction of the fluid and solid phases of the tissue as they flow relative to one another. The present study is concerned with the role of this interaction under uniaxial stress relaxation in compression. The model is a biphasic mixture of fluid and solid which incorporates the strain-dependent permeability found earlier from permeation experiments. When a ramp-displacement is imposed on the articular surface, simple, but accurate, asymptotic approximations are derived for the deformation and stress fields in the tissue for slow and moderately fast rates of compression. They are shown to agree very well with experiment and they provide a simple means for determining the material parameters. Moreover, they lead to important insights into the role of the flow-dependent viscoelastic nature of articular cartilage and other hydrated biological tissues.
TL;DR: A measure of diet is developed that is sensitive over the whole spectrum of primate feeding niches, and this measure is used to define the relationship between body size and diet for a sample of 72 primate species.
Abstract: The feeding niche and the body size of any species are fundamental parameters that constrain the evolution of many other phenotypic characters. Moreover, previous work has shown that body size and diet are correlated, as a consequence of the negative allometry of metabolic rate. Unfortunately, the precise form of the association between body size and diet has never been specified, principally because no suitable cross-species measure of diet has been advanced. Here we develop a measure of diet that is sensitive over the whole spectrum of primate feeding niches, and use this measure to define the relationship between body size and diet for a sample of 72 primate species. Subsequently, we present several examples of how behavioral and ecological hypotheses can be tested by examining the extent to which particular species deviate from the general diet-body size pattern.
TL;DR: In this paper, the authors calculated the contiguity of liquid phase sintered materials for various interfacial energies, grain size ratios, and volume fractions of solid phase, and correlated the results to prior observations on cemented carbides.
Abstract: Contiguity is a measure of the dispersed phase contact area in a composite microstructure and is particularly important to the properties of liquid phase sintered materials. For an assumed spherical geometry, the contiguity is calculated for various interfacial energies, grain size ratios, and volume fractions of solid phase. The volume fraction solid is linked to the dihedral angle to indicate conditions where grain shape accommodation is necessary. The effect of a distribution in solid phase grain sizes is to lower slightly the contiguity from the monosized grain value. Coalescence is linked to the occurrence of curved boundaries at intergrain contacts involving differing grain sizes. The results are correlated to prior observations on cemented carbides.
TL;DR: The quantitative morphometric method was sufficiently sensitive to demonstrate a dose-response effect of ethanol and aspirin and provides a sensitive method to quantitate either a few small, or numerous large, regularly or irregularly shaped hemorrhagic and nonhemorrhagic gastric mucosal lesions.
TL;DR: Subjects' judgments about the similarity of 20 stimulus jobs were analyzed with a metric multidimensional scaling algorithm (Common Space Analysis) in order to identify the dimensions along which the jobs can be compared.
Abstract: Subjects' judgments about the similarity of 20 stimulus jobs were analyzed with a metric multidimensional scaling algorithm (Common Space Analysis) in order to identify the dimensions along which i...
TL;DR: In this article, a quasilinear Hopf-bifurcation analysis of the marginal stability boundary of a uniformly heated boiling channel is presented. But the analysis is restricted to the case when the effects of gravity and friction are considered.
Abstract: Thermally induced flow instabilities in uniformly heated boiling channels have been studied analytically. The classical homogeneous equilibrium model was used. This distributed model was transformed into an integrodifferential equation for inlet velocity. A linear analysis showed interesting features (i.e. islands of instability) of the marginal stability boundary which appear when the effects of gravity and friction were systematically considered. A quasilinear Hopf-bifurcation analysis, valid near the marginal-stability boundaries, gives the amplitude and frequency of limit-cycle oscillations that can appear on the unstable side of the boundary. The analysis also shows cases where a finite-amplitude perturbation can cause a divergent instability on the stable side of the linear-stability boundary.
TL;DR: Petrological data from intercalated pelitic schists and greenstones are used to construct a pressure-temperature path followed by the Upper Schieferhulle (USH) series during progressive metamorphism and uplift in the south-west Tauern Window, Italy as mentioned in this paper.
Abstract: Petrological data from intercalated pelitic schists and greenstones are used to construct a pressure–temperature path followed by the Upper Schieferhulle (USH) series during progressive metamorphism and uplift in the south-west Tauern Window, Italy. Pseudomorphs of Al–epidote + Fe-epidote + albite + oligoclase + chlorite after lawsonite and data on amphibole crystal chemistry indicate early metamorphism in the lawsonite-albite-chlorite subfacies of the blueschist facies at P± 7–8 kbar. Geothermometry and geobarometry yield conditions of final equilibration of the matrix assemblage of 475±25°C, 5–6 kbar; calculations with plagioclase and phengite inclusions in garnet indicate early garnet growth at pressures of ∼ 7.5 kbar. Garnet zoning patterns are complex and reversals in zoning can be correlated between samples. Thermodynamic modelling of these zoning profiles implies garnet growth in response to four distinct phases of tectonic activity. Fluid inclusion data from coexisting immiscible H2O–CO2–NaCl fluids constrain the uplift path to have passed through temperatures of 380 + 30°C at 1.3 + 0.2 kbar.
There is no evidence for metamorphism of USH at pressures greater than ∼ 7.5 kbar in this area of the Tauern Window. This is in contrast to pressures of ± 10 kbar recorded in the Lower Schieferhulle only 2–3 km across strike. A history of differential uplift and thinning of the intervening section during metamorphism is necessary to reconcile the P–T data obtained from these adjacent tectonic units.
TL;DR: An exact procedure is developed for determining an optimal path when the utility function is quadratic—a case where permanent preferences do not always prevail and an efficient Dijkstra-type algorithm is available that determines the optimal path.