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Showing papers by "Rensselaer Polytechnic Institute published in 1991"


Journal ArticleDOI
TL;DR: In this article, a series of vapor-absent (i.e., Pfluid < Ptotal) melting experiments on four natural basaltic compositions were conducted at 8, 16, 22 and 32 kbar in order to assess the validity of models for the origin of Archean granitoids which assume a mafic crustal source.

1,142 citations


Journal ArticleDOI
TL;DR: Refinements in training procedures and in the distribution-based method used to translate mu rhythm amplitudes into cursor movements should further improve this 1-dimensional control.

1,115 citations


Journal ArticleDOI
TL;DR: In this article, a general framework for the analysis of the attitude tracking control problem for a rigid body is presented and a large family of globally stable control laws are obtained by using the globally nonsingular unit quaternion representation in a Lyapunov function candidate whose form is motivated by the consideration of the total energy of the rigid body.
Abstract: A general framework for the analysis of the attitude tracking control problem for a rigid body is presented. A large family of globally stable control laws is obtained by using the globally nonsingular unit quaternion representation in a Lyapunov function candidate whose form is motivated by the consideration of the total energy of the rigid body. The controllers share the common structure of a proportional-derivative feedback plus some feedforward which can be zero (the model-independent case), the Coriolis torque compensation, or an adaptive compensation. These controller structures are compared in terms of the requirement on the a priori model information, guaranteed transient performance, and robustness. The global stability of the Luh-Walker-Paul robot end-effector controller is also analyzed in this framework. >

1,000 citations



Journal ArticleDOI
TL;DR: This paper examines a powerful electrical technique by which cell motion is quantitatively measured at the nanometer level and it is clear that under these circumstances the average motions of the cell layer of 1 nm can be inferred from the measurements.
Abstract: Motility is a fundamental property of mammalian cells that normally is observed in tissue culture by time lapse microscopy where resolution is limited by the wavelength of light. This paper examines a powerful electrical technique by which cell motion is quantitatively measured at the nanometer level. In this method, the cells are cultured on small evaporated gold electrodes carrying weak ac currents. A large change in the measured electrical impedance of the electrodes is observed when cells attach and spread on these electrodes. When the impedance is tracked as a function of time, fluctuations are observed that are a direct measure of cell motion. Surprisingly, these fluctuations continue even when the cell layer becomes confluent. By comparing the measured impedance with a theoretical model, it is clear that under these circumstances the average motions of the cell layer of 1 nm can be inferred from the measurements. We refer to this aspect of cell motility as micromotion.

836 citations


Journal ArticleDOI
TL;DR: In this article, a two-fluid model of multidimensional laminar bubbly two-phase flow is developed and used to analyze vertical pipe flows and a Galerkin finite element method is utilized to perform the numerical evaluations.

729 citations


Proceedings ArticleDOI
03 Jun 1991
TL;DR: A critical study of laminar-turbulent transition phenomena and its role in aerodynamics and heat transfer in modern and future gas turbine engines is presented in this article, where a current look at transition phenomena from both a theoretical and experimental standpoint are provided and a comprehensive state-of-the-art account of transitional phenomena in the engine's throughflow components given.
Abstract: A critical study of laminar-turbulent transition phenomena and its role in aerodynamics and heat transfer in modern and future gas turbine engines is presented. In order to develop a coherent view of the subject, a current look at transition phenomena from both a theoretical and experimental standpoint are provided and a comprehensive state-of-the-art account of transitional phenomena in the engine’s throughflow components given. The impact of transitional flow on engine design is discussed and suggestions for future research and developmental work provided.Copyright © 1991 by ASME

467 citations


Journal ArticleDOI
TL;DR: The lack of a clear understanding of what constitutes organizational politics has been referred to as omnipresent as well as elusive as discussed by the authors, and this elusiveness arises because of the lack of an understanding of organizational politics.
Abstract: Organizational politics has been referred to as omnipresent as well as elusive. This elusiveness arises because of the lack of a clear understanding of what constitutes organizational politics. The...

457 citations


Journal ArticleDOI
TL;DR: This paper generalizes the well-known Sch6nhage-Strassen algorithm for multiplying large integers to an algorithm for dividing polynomials with coefficients from an arbitrary, not necessarily commutative, not always associative, algebra d, and obtains a method not requiring division that is valid for any algebra.
Abstract: In this paper we generalize the well-known Sch6nhage-Strassen algorithm for multiplying large integers to an algorithm for multiplying polynomials with coefficients from an arbitrary, not necessarily commutative, not necessarily associative, algebra d . Our main result is an algorithm to multiply polynomials of degree < n in O (n log n) algebra multiplications and O (n log n loglog n) algebra additions/subtractions (we count a subtraction as an addition). The constant implied by the \"0 \"does not depend upon the algebra ~4. The parallel complexity of our algorithm, i.e., the depth of the corresponding arithmetic circuit, is O (log n). When division by 2 is possible, then the Sch6nhage-Strassen [-13] integer multiplication algorithm can be easily reformulated as a polynomial multiplication procedure (c.f. [11]). Sch6nhage [12] investigated the polynomial multiplication problem for arbitrary fields of characteristic 2, in which the standard U-point Discrete Fast Fourier Transform algorithm (DFT) cannot be used because it requires division by 2. The fields over which the DFT is used do not necessarily contain the primitive roots of unity necessary for the computation of the Discrete Fast Fourier Transform and, to use it, such roots must be adjoined to the ground field. It is this which increases the complexity from O (n log n) to O(n log n loglog n). Sch6nhage's algorithm for fields of characteristic 2 uses a 3k-point Fourier transform. When division by 3 is possible, he obtains again an algorithm of complexity O(n log n loglog n). His approach does not appear to generalize to s k transforms, even when s = 5. Here, we exhibit an alternate method that works for order s k for any integer s > 2. By applying this method for two relatively prime values of s, we obtain a method not requiring division. As a result our method is valid for any algebra

419 citations


Journal ArticleDOI
TL;DR: The structural diversity and wide-ranging potencies of the analogs described herein provide the opportunity to develop a pharmacophore for the cannabinoids using molecular modeling techniques.
Abstract: Numerous cannabinoids have been synthesized that are extremely potent in all of the behavioral assays conducted in our laboratory. An important feature in increasing potency has been the substitution of a dimethylheptyl (DMH) side chain for the pentyl side chain. Our previous studies have shown that (−)-11-OH-Δ8-THC-dimethylheptyl was 80–1150 times more potent than Δ9-THC. Stereospecificity was demonstrated by its (+)- enantiomer which was more than 1400–7500 times less potent. A related series of DMH cannabinoid analogs has recently been synthesized and preliminary evaluations reported here. (−)-11-OH-Δ9-THC-DMH was found to be equipotent with (−)-11-OH-Δ8-THC-DMH. The aldehyde (−)-11-oxo-Δ9-THC-DMH was 15–50 times more potent than Δ9-THC. Surprisingly, (−)-11-carboxy-Δ9-THC-DMH was also active, being slightly more potent than Δ9-THC. In the bicyclic cannabinoid series, the length and bulk of the side chain were found to be equally important. Aminoalkylindoles, which are structurally dissimilar from classical cannabinoids, have been found to exhibit a pharmacological profile similar to Δ9-THC. Though not extremely potent in vivo, they appear to represent an entirely new approach to studying the actions of the cannabinoids. The structural diversity and wide-ranging potencies of the analogs described herein provide the opportunity to develop a pharmacophore for the cannabinoids using molecular modeling techniques.

416 citations


Journal ArticleDOI
TL;DR: In this article, a search for systematic relationships between spectral features and compositional variations and to assess the applicability of reflectance spectroscopy to pyroxene geothermometry was conducted.
Abstract: Pyroxene reflectance and transmittance spectra have been examined in a search for systematic relationships between spectral features and compositional variations and to assess the applicability of reflectance spectroscopy to pyroxene geothermometry. Orthopyroxenes containing up to about 11 percent Wollastonite show a positive correlation between Fe(2+) content and wavelength positions of the major absorption bands. Aluminum-rich orthopyroxenes display absorption bands at lower than expected wavelengths. Spectral-compositional relationships are more complex for clinopyroxenes, showing both positive and negative correlations between band positions and major cation abundances. These relationships are further complicated by the presence of significant amounts of other transition series elements such as Ti and Cr and by the presence of exsolved phases and compositional zonations. Contours of the wavelength positions of band minima projected onto the pyroxene tetralateral generally exhibit concave downward shapes. The orientations of the contours relative to pyroxene geotherms are such as to effectively preclude the use of spectroscopy to significantly constrain the temperatures of formation of pyroxenes.

Journal ArticleDOI
TL;DR: The silicon oxycarbide structure deduced from these results is a random network of silicon-oxygen tetrahedra, with some silicons bonded to one or two carbons substituted for oxygen as discussed by the authors.
Abstract: Silicon oxycarbide glass is formed by the pyrolysis of silicone resins and contains only silicon, oxygen, and carbon. The glass remains amorphous in x-ray diffraction to 1400 °C and shows no features in transmission electron micrographs (TEM) after heating to this temperature. After heating at higher temperature (1500–1650 °C) silicon carbide lines develop in x-ray diffraction, and fine crystalline regions of silicon carbide and graphite are found in TEM and electron diffraction. XPS shows that silicon-oxygen bonds in the glass are similar to those in amorphous and crystalline silicates; some silicons are bonded to both oxygen and carbon. Carbon is bonded to either silicon or carbon; there are no carbon-oxygen bonds in the glass. Infrared spectra are consistent with these conclusions and show silicon-oxygen and silicon-carbon vibrations, but none from carbon-oxygen bonds. 29Si-NMR shows evidence for four different bonding groups around silicon. The silicon oxycarbide structure deduced from these results is a random network of silicon-oxygen tetrahedra, with some silicons bonded to one or two carbons substituted for oxygen; these carbons are in turn tetrahedrally bonded to other silicon atoms. There are very small regions of carbon-carbon bonds only, which are not bonded in the network. This “free” carbon colors the glass black. When the glass is heated above 1400 °C this network composite rearranges in tiny regions to graphite and silicon carbide crystals. The density, coefficient of thermal expansion, hardness, elastic modulus, index of refraction, and viscosity of the silicon oxycarbide glasses are all somewhat higher than these properties in vitreous silica, probably because the silicon-carbide bonds in the network of the oxycarbide lead to a tighter, more closely packed structure. The oxycarbide glass is highly stable to temperatures up to 1600 °C and higher, because oxygen and water diffuse slowly in it.

Journal ArticleDOI
TL;DR: Responses of neonatal rat calvarial osteoblasts to a variety of orthopedic implant materials were examined in vitro and cell adhesion and growth were similar on nonapatitic materials.
Abstract: Responses of neonatal rat calvarial osteoblasts to a variety of orthopedic implant materials were examined in vitro. Attachment, proliferation, and collagen synthesis of a well-characterized line of osteoblasts with 316L stainless steel, Ti-6Al-4V, Co-Cr-Mo, PMMA, hydroxyapatite, borosilicate glass, and tissue culture polystyrene were studied. Cell adhesion and growth were similar on nonapatitic materials. In contrast, attachment and growth of osteoblasts were significantly lower and slower, respectively, on hydroxyapatite. Collagen synthesis per cell and relative collagen synthesis, however, were comparable on all the materials tested.

Journal ArticleDOI
01 Aug 1991
TL;DR: A theoretical basis for Petri net synthesis methods is provided that can be used to model systems with shared resources, and to make the resulting nets bounded, live, and reversible.
Abstract: A theoretical basis for Petri net synthesis methods is provided that can be used to model systems with shared resources, and to make the resulting nets bounded, live, and reversible. Two resource-sharing concepts, parallel mutual exclusion (PME) and sequential mutual exclusion (SME), are formulated in the context of the Petri net theory. A PME models a resource shared by distinct independent processes, and an SME is a sequential composition of PMEs, modeling a resource shared by sequentially related processes. The conditions under which a net containing such structures remains bounded, live, and reversible are derived. >

Proceedings ArticleDOI
08 Apr 1991
TL;DR: In this article, the authors describe an implementation of genetic search methods in multicriterion optimal designs of structural systems with a mix of continuous, integer and discrete design variables, and two distinct strategies to simultaneously generate a family of Pareto optimal designs are presented.
Abstract: The present paper describes an implementation of genetic search methods in multicriterion optimal designs of structural systems with a mix of continuous, integer and discrete design variables. Two distinct strategies to simultaneously generate a family of Pareto optimal designs are presented in the paper. These strategies stem from a consideration of the natural analogue, wherein distinct species of life forms share the available resources of an environment for sustenance. The efficacy of these solution strategies are examined in the context of representative structural optimization problems with multiple objective criteria and with varying dimensionality as determined by the number of design variables and constraints.

Proceedings ArticleDOI
01 Jul 1991
TL;DR: This work proposes a new approach to the problem of generating a simple topologically-closed geometric model from a point-sampled volume data set, called Geometrically Deformed Model or GDM, which is created by placing a 'seed' model in thevolume data set.
Abstract: We propose a new approach to the problem of generating a simple topologically-closed geometric model from a point-sampled volume data set. We call such a model a Geometrically Deformed Model or GDM. A GDM is created by placing a 'seed' model in the volume data set. The model is then deformed by a relaxation process that minimizes a set of constraints that provides a measure of how well the model fits the features in the data. Constraints are associated with each vertex in the model that control local deformation, interaction between the model and the data set, and the shape and topology of the model. Once generated, a GDM can be used for visualization, shape recognition, geometric measurements, or subjected to a series of geometric operations. This technique is of special importance because of the advent of nondestructive sensing equipment (CT, MRI) that generates point samples of true three-dimensional objects.

Journal ArticleDOI
TL;DR: In this paper, the authors used finite difference models of Fe-Mg diffusion in garnet undergoing cooling from metamorphic peak conditions to infer the significance of temperatures calculated using garnet-biotite Fe-mg exchange thermometry.
Abstract: Finite difference models of Fe-Mg diffusion in garnet undergoing cooling from metamorphic peak conditions are used to infer the significance of temperatures calculated using garnet-biotite Fe-Mg exchange thermometry. For rocks cooled from high grades where the garnet was initially homogeneous, the calculated temperature (Tcalc) using garnet core and matrix biotite depends on the size of the garnet, the ratio of garnet to biotite in the rock (Vgarnet/Vbiotite) and the cooling rate. For garnets with radii of 1 mm and Vgarnet/Vbiotite<1, Tcalc is 633, 700 and 777°C for cooling rates of 1, 10 and 100°C/Ma. For Vgarnet/Vbiotite= 1 and 4 and a cooling rate of 10° C/Ma, Tcalc is approximately 660 and 610° C, respectively. Smaller and larger garnets have lower and higher Tcalc, respectively. These results suggest that peak metamorphic temperatures may be reliably attained from rocks crystallized at conditions below Tcalc of the garnet core, provided that Vgarnet/Vbiotite is sufficiently small (<0.1) and that the composition of the biotite at the metamorphic peak has not been altered during cooling. Numerical experiments on amphibolite facies garnets with nominal peak temperatures of 550–600° C generate a ‘well’in Fe/(Fe + Mg) near the rim during cooling. Maximum calculated temperatures for the assemblage garnet + chlorite + biotite + muscovite + plagioclase + quartz using the Fe/(Fe + Mg) at the bottom of the ‘well’with matrix biotite range from 23–43° C to 5–12° C below the peak metamorphic temperature for cooling rates of 1 and 100° C/Ma, respectively. Maximum calculated temperatures for the assemblage garnet + staurolite + biotite + muscovite + plagioclase + quartz are approximately 70° C below the peak metamorphic temperature and are not strongly dependent on cooling rate. The results of this study indicate that it may be very difficult to calculate peak metamorphic temperatures using garnet-biotite Fe-Mg exchange thermometry on amphibolite facies rocks (Tmax > 550° C) because the rim composition of the garnet, which is required to calculate the peak temperature, is that most easily destroyed by diffusion.

Journal ArticleDOI
31 Oct 1991
TL;DR: Presents the design, implementation, and performance of Rensselaer's third-generation adaptive current tomograph, ACT3, a 32-electrode system that is capable of applying arbitrary spatial patterns of current.
Abstract: Presents the design, implementation, and performance of Rensselaer's third-generation adaptive current tomograph, ACT3. This system uses 32 current sources and 32 phase-sensitive voltmeters to make a 32-electrode system that is capable of applying arbitrary spatial patterns of current. The instrumentation provides 16 b precision on both the current values and the real and reactive voltage readings and can collect the data for a single image in 133 ms. Additionally, the instrument is able to automatically calibrate its voltmeters and current sources and adjust the current source output impedance under computer control. The major system components are discussed in detail and performance results are given. Images obtained using stationary agar targets and a moving pendulum in a phantom as well as in vivo resistivity profiles showing human respiration are shown. >

Journal ArticleDOI
01 Apr 1991
TL;DR: Five types of representations for assembly sequences are reviewed and the mappings of one representation into the others are established, and the correctness and completeness of these representations are established.
Abstract: Five types of representations for assembly sequences are reviewed: the directed graph of feasible assembly sequences; the AND/OR graph of feasible assembly sequences; the set of establishment conditions, and two types of precedence relationships namely those between the establishment of one connection between parts and the establishment of another connection, and those between the establishment of one connection and states of the assembly process. The mappings of one representation into the others are established. The correctness and completeness of these representations are established. The results presented are needed in the proof of correctness and completeness of algorithms for the generation of mechanical assembly sequences. >

Journal ArticleDOI
TL;DR: In this article, the effects of pH, X H 2 O (addition of CO 2 ), pressure (P = 1.0-3.0 GPa), temperature (T = 800-1200 °C), and dissolved silicate and NaCl concentration on the solubility of accessory minerals (apatite, monazite, zircon and rutile) in supercritical aqueous fluids have been measured.
Abstract: Solubilities of accessory minerals (apatite, monazite, zircon and rutile) in supercritical aqueous fluids have been measured to evaluate the role of these fluids in the mobilization of accessory mineral-hosted trace elements. We have characterized the effects on solubility of pH, X H 2 O (addition of CO 2 ), pressure ( P = 1.0-3.0 GPa), temperature ( T =800-1200 °C), and dissolved silicate and NaCl concentration. Fluorapatite solubility in pure H 2 O is low, not more than 0.4 wt% at all conditions studied, but increases strongly with decreasing pH. Changes in P, T, X H 2 O M NaCl (the molality of NaCl), and dissolved silicate concentration have comparatively little effect on apatite solubility. Monazite is even less soluble in H 2 O (not more than 0.2 wt% ). Limited data suggests that monazite solubility increases with increasing P and T and with decreasing pH, but is insensitive to M NaCl . Zircon reacts with H 2 O to form baddeleyite (ZrO 2 ) + silica-rich fluid. ZrO 2 solubility in H 2 O and 1 m HCl is less than 0.2 wt% . Zircon, and therefore ZrO 2 , solubility in quartz-saturated fluids± HCl ±NaCl and in H 2 O -CO 2 fluids is also very low. Rutile is more soluble than the other minerals examined, in the wt% range, and its solubility increases with increasing P and T . Results indicate that high P-T aqueous fluids can dissolve significant amounts of Ti but very little Zr, and little phosphate unless the fluids are acidic. In most cases, apatite, monazite and zircon will remain present during episodes of aqueous fluid metasomatism and therefore will exert control, as ‘residual phases’, over element distribution. The higher solubility of rutile relative to other accessory minerals at high pressure may result in the depletion of high field strength elements relative to large ion lithophile elements observed in subduction zone volcanics.

Journal ArticleDOI
TL;DR: The review traces the evolution of models from single-criterion optimizations to multiobjective analyses, and highlights the emerging direction of dealing explicitly with distributions of outcomes, rather than simply optimizing expected values.
Abstract: We survey research on hazardous materials transportation in the areas of risk analysis, routing/scheduling and facility location. Our focus is primarily on work done since 1980, and on research which is methodological rather than empirical. We also limit our focus to transport by land-based vehicles (truck and rail), excluding pipeline, air and maritime movements. The review traces the evolution of models from single-criterion optimizations to multiobjective analyses, and highlights the emerging direction of dealing explicitly with distributions of outcomes, rather than simply optimizing expected values. We also indicate examples of work which integrate risk analysis with routing, and routing with facility location. We conclude with a discussion of several aspects of hazardous materials transportation which offer important challenges for further research.

Journal ArticleDOI
TL;DR: The basis for a visual performance model is described and how it can be applied using a computer imaging device and how to compute visual performance for real tasks is described.
Abstract: Visual performance is defined in terms of the speed and accuracy of processing visual information. To evaluate illuminated tasks in terms of visual performance, it is necessary to have a valid computational model that relates measurable, salient aspects of the visual environment (e.g. target contrast) to measurable human responses (e.g. visual response time). A model of visual performance should be independent of the influence of non-visual factors as they influence speed and accuracy. It is also important to have practical application tools that can measure the salient aspects of the visual environment and compute (predict) visual performance for real tasks. This paper describes the basis for a visual performance model and how it can be applied using a computer imaging device.

Journal ArticleDOI
TL;DR: Silicon polymers were pyrolyzed to form silicon oxycarbides that contained only silicon, oxygen, and carbon, and NMR showed that the polymers had a silicon-oxygen backbone with branching and ring units as discussed by the authors.
Abstract: Silicone polymers were pyrolyzed to form silicon oxycarbides that contained only silicon, oxygen, and carbon. The starting polymers were mainly methyl trichlorosilane with a small amount of dimethyl dichlorosilane. NMR showed that the polymers had a silicon-oxygen backbone with branching and ring units. When the polymer was heated in hydrogen, toluene and isopropyl alcohol, used in production of the polymer, were given off in the temperature range 150 °C to 500 °C. Substantial decomposition of the polymer itself began only above about 700°by evolution of methane. The network of silicon-oxygen bonds and silicon-carbon bonds did not react and was preserved; the silicon-carbon bonds were linked into the silicon-oxygen network. The silicon oxycarbide was stable above 1000 °C, showing no dimensional changes above this temperature. The interior of the silicon oxycarbide was at very low effective oxygen pressure because oxygen diffused slowly in it. There was also a protective layer of silicon dioxide on the surface of the silicon oxycarbide.

Journal ArticleDOI
01 Sep 1991-Geology
TL;DR: In this paper, slip vectors from thrust earthquakes at the Java Trench southwest of Sumatra demonstrate that the Sumatran fore arc is not a single rigid plate that is translated to the northwest by oblique plate convergence, but instead they indicate arc-parallel stretching of the fore arc at a uniform strain rate of 3-4 x 10 -8 /yr.
Abstract: Slip vectors from thrust earthquakes at the Java Trench southwest of Sumatra demonstrate that the Sumatran fore arc is not a single rigid plate that is translated to the northwest by oblique plate convergence. Instead they indicate arc-parallel stretching of the fore arc at a uniform strain rate of 3-4 x 10 -8 /yr. The northwestward motion of the fore arc relative to the upper plate (Southeast Asia) increases from near zero at the Sunda Strait to 45-60 mm/yr in northwest Sumatra and should result in variable slip rates on the Sumatran fault.


Journal ArticleDOI
TL;DR: In this paper, a laboratory experiment was designed to test the influence of subordinate impression management on two aspects of the performance appraisal process: supervisor ratings of subordinate performance and supervisor verbal communication in a performance appraisal interview.

Journal ArticleDOI
01 Jan 1991-Virology
TL;DR: Four recombinant vaccinia viruses engineered for expression of different portions of the Japanese encephalitis virus (JEV) open reading frame provided protection against lethal challenge with JEV and were correlated with the production of high titers of neutralizing and hemagglutination-inhibiting antibodies.

Journal ArticleDOI
TL;DR: In this article, the authors consider the rescheduling of operations with release dates and multiple resources when disruptions prevent the use of a preplanned schedule, and the overall strategy is to follow the preschedule until a disruption occurs.
Abstract: This paper considers the rescheduling of operations with release dates and multiple resources when disruptions prevent the use of a preplanned schedule. The overall strategy is to follow the preschedule until a disruption occurs. After a disruption, part of the schedule is reconstructed to match up with the preschedule at some future time. Conditions are given for the optimality of this approach. A practical implementation is compared with the alternatives of preplanned static scheduling and myopic dynamic scheduling. A set of practical test problems demonstrates the advantages of the matchup approach. We also explore the solution of the matchup scheduling problem and show the advantages of an integer programming approach for allocating resources to jobs.

Journal ArticleDOI
TL;DR: The authors consider both the maximum a posteriori probability (MAP) estimate and the minimum mean-squared error (MMSE) estimate for image estimation and image restoration for images modeled as compound Gauss-Markov random fields.
Abstract: Algorithms for obtaining approximations to statistically optimal estimates for images modeled as compound Gauss-Markov random fields are discussed. The authors consider both the maximum a posteriori probability (MAP) estimate and the minimum mean-squared error (MMSE) estimate for image estimation and image restoration. Compound image models consist of several submodels having different characteristics along with an underlying structure model which govern transitions between these image submodels. Two different compound random field models are employed, the doubly stochastic Gaussian (DSG) random field and a compound Gauss-Markov (CGM) random field. The authors present MAP estimators for DSG and CGM random fields using simulated annealing. A fast-converging algorithm called deterministic relaxation, which, however, converges to only a locally optimal MAP estimate, is also presented as an alternative for reducing computational loading on sequential machines. For comparison purposes, the authors include results on the fixed-lag smoothing MMSE estimator for the DSG field and its suboptimal M-algorithm approximation. >

Journal ArticleDOI
TL;DR: In this article, a review of recent literature on human cognition identified several factors that may play a role in determining whether conflict yields predominantly positive or negative effects, such as the impact of strong negative emotions on cognition, stereotype-driven thinking, and attributional processes.
Abstract: Managers rated the extent to which conflict produces both positive and negative effects. Results indicated that they rated several negative effects significantly higher than any positive effects. However, virtually all managers reported personal experiences in which conflict yielded beneficial outcomes. These and other findings suggest that practicing managers perceive conflict as having the potential to yield positive as well as negative effects. A review of recent literature on human cognition identified several factors that may play a role in determining whether conflict yields predominantly positive or negative effects. These factors include the impact of strong negative emotions on cognition, stereotype-driven thinking, and attributional processes. Techniques for modifying conflict situations so that they are more likely to result in positive effects are suggested.