Showing papers by "University of Houston published in 1980"
TL;DR: In this paper, the authors developed models for predicting flow pattern transitions during steady gas-liquid flow in vertical tubes based on physical mechanisms suggested for each transition, incorporating the effect of fluid properties and pipe size.
Abstract: Models for predicting flow pattern transitions during steady gas-liquid flow in vertical tubes are developed, based on physical mechanisms suggested for each transition. These models incorporate the effect of fluid properties and pipe size and thus are largely free of the limitations of empirically based transition maps or correlations.
1,277 citations
TL;DR: In this article, the conditions most favorable to vortex parting were determined as a function of the excitation Strouhal number, the Reynolds number, and the initial shear-layer state.
Abstract: Hot-wire and flow visualization studies were performed in three air jets subjected to pure-tone excitation The instability, vortex roll-up, and transition to the controlled excitation were investigated The conditions most favorable to vortex parting were determined as a function of the excitation Strouhal number, the Reynolds number, and the initial shear-layer state; it was shown that the rolled-up vortex rings undergo pairing under 'the shear layer mode', and the 'jet-column mode' when the Strouhal numbers based on the initial shear-layer momentum thickness are 0012 and 085, respectively Coherent ring-like vortical structures could be educed to the end of the potential core; however, the paired vortex becomes weaker with increasing downstream distances The transverse transport of 'u' momentum by the coherent structures was much larger during the pairing process than in regions where a single vortex is studied
469 citations
TL;DR: In this article, the current status of retrospection in psychological research is reviewed, and issues are considered for future research needed to identify the unique strengths and limitations of retrospective approaches, and the superiority of retrospective ratings over tradittonal self-report pretest ratings in providing a measure of change is reviewed.
Abstract: Evaluations of experimental interventions which employ self-report measures are subject to an instrumentation-related source of contamination known as response-shift bias. The difficulty arises when the experimental intervention changes the subject's evaluation standard with regard to the dimension measured with the self-report instrument. In such cases even the true experimental designs (Designs 4, 5, and 6; Campbell and Stanlev, 1963) can provide internally invalid results. Retrospective pretest ratings are recommended as one way in which response-shift bias might be attenuated. Research demonstrating re sponse-shift effects and the superiority of retrospective ratings over tradittonal self-report pretest ratings in providing a measure of change is reviewed. Finally, the current status of retrospection in psychological research is reviewed, and issues are considered for future research needed to identify the unique strengths and limitations of retrospective approaches.
434 citations
TL;DR: This article reviewed issues and questions concerning punishment, reviewed existing research to delimit variables that influence the effectiveness of punishment, and discussed research issues associated with the study of punishment in organizational contexts.
Abstract: The topic of punishment has received essentially no attention from organizational researchers. Our purpose in this paper is to review issues and questions concerning punishment, to review existing research to delimit variables that influence the effectiveness of punishment, and to discuss research issues associated with the study of punishment in organizational contexts.
259 citations
TL;DR: In this paper, experimental measurements of flow patterns for gas-liquid flow in inclined pipes are reported, and the results compare well with a recently published theory for the prediction of flow pattern in horizontal and inclined pipes.
220 citations
TL;DR: In this paper, the coherent structure dynamics in the near field of a circular jet has been experimentally explored by inducing stable vortex pairing through controlled excitation and applying phase-averaging techniques.
Abstract: The coherent structure dynamics in the near field of a circular jet has been experimentally explored by inducing ‘stable’ vortex pairing through controlled excitation (see Zaman & Hussain 1980) and applying phase-averaging techniques. Hot-wire measurements were made in a 7·62 cm air jet with laminar exit boundary layer at the Reynolds number ReD = 3·2 × 104, excited at the Strouhal number StD = 0·85. At a particular phase during the pairing process, spatial distributions of the phase-average longitudinal and lateral velocity perturbations (〈u)〉, 〈v〉), vorticity, streamlines, the coherent and background Reynolds stresses and turbulence intensities have been educed. These data have been obtained for four different locations occupied by the vortices at the same phase (preceding, during, and following the pairing event), in the region 0 < x/D < 5. Spatial distributions of these measures at four successive phases during the pairing process are also educed in an attempt to further understand the vortex-pairing dynamics. The flow physics is discussed on the basis of measurements over the physical extent of the vortical structures, phase-locked to specific phases of the pairing event and thus do not involve use of the Taylor hypothesis.The computed pseudostream functions at particular phases are compared with the corresponding streamlines drawn by the method of isoclines. Transition of the vortices is examined on the basis of vorticity diffusion, the superimposed random fluctuation field intensities and Reynolds stress and phase-locked circumferential correlation measurements. The peak vorticity drops rapidly owing to transition and interaction of the vortices during pairing but, farther downstream, the decay can be attributed to destruction of the coherent vorticity by the background turbulence Reynolds stress, especially at the locations of the latter's ‘saddle points’. Controlled excitation enhances the initial circumferential coherence of the vortical structures, but is ineffective in delaying turbulent breakdown near the end of the potential core; the breakdown appears to occur through evolution of the circumferential lobe structures. The coherent structure Reynolds stress is found to be much larger than the background turbulence Reynolds stress for 0 < x/D [lsim ] 3, but these two are comparable near the end of the jet potential core. The zone average of the coherent structure Reynolds stress over the cross-section of the merging vortex pair is much larger than that over a single vortical structure either before or after the completion of pairing. During the pairing process, such average correlations are found to be the largest at an early phase of the process while entrainment, turbulent breakdown as well as rapid diffusion of vorticity occur at a later phase. The regions of alternate positive and negative coherent Reynolds stresses associated with the structures and their interactions help explain ‘negative production’.
204 citations
TL;DR: An optimal procedure is developed by modeling the system as a constrained generalized network with fixed charge arcs and side constraints that yields optimal lot sizing decisions for all purchases as well as manufactured goods and components in all periods over a finite planning horizon.
Abstract: The wide spread use of advanced information systems such as Material Requirements Planning MRP has significantly altered the practice of dependent demand inventory management. Recent research has focused on development of multi-level lot sizing heuristics for such systems. In this paper, we develop an optimal procedure for the multi-period, multi-product, multi-level lot sizing problem by modeling the system as a constrained generalized network with fixed charge arcs and side constraints. The network permits us to relax some of the more restrictive assumptions of previous models such as those designed for product structures with single sources or successors.
The solution to the resulting minimum cost flow problem yields optimal lot sizing decisions for all purchases as well as manufactured goods and components in all periods over a finite planning horizon. A simple illustration, beginning with a master production schedule and bills of material, illustrates the suitablility of this approach for modeling complex requirements planning systems.
Optimal solutions obtained by this method may also be useful in comparing results obtained from future heuristic approaches which may be more computationally efficient.
139 citations
TL;DR: Results generally confirmed hypotheses made by the E that Autobiographical Recollections was the superior method for inducing and altering depression and anxiety in a population that included both sexes.
Abstract: Compared two primary induction methods that have cognitive bases, Autobiographical Recollections and Structural Set of Mood Statements, by assessing their effectiveness in inducing depression and elation moods, respectively. Eighty-three male and 123 female undergraduate college students were assigned randomly to 1 of 15 groups. Each person who participated in the experiment received a depression-related induction or a control followed by an elation-related induction or a control. The effects of each induction were measured by three independent variables: Two depression measured and one anxiety measure. Results generally confirmed hypotheses made by the E that Autobiographical Recollections was the superior method for inducing and altering depression and anxiety in a population that included both sexes.
133 citations
TL;DR: In this article, Histo-pathology of cones in a blue-blinded retina was compared with cytochemical labeling of short-wavelength cones, revealing that they follow a similar distribution: are sparse in the foveola.
130 citations
TL;DR: The present status of the knowledge of the importance of fluid mechanics in the initiation and progression of arterial lesions is summarized on the basis of the experimental data presented at the meeting.
Abstract: A specialists meeting on "The Role of Fluid Mechanics in Atherogenesis" was held August 24-25, 1978, at The Ohio State University This meeting was a followup to a similar meeting held in 1974 [1, 2] The present status of our knowledge of the importance of fluid mechanics in the initiation and progression of arterial lesions is summarized on the basis of the experimental data presented at the meeting; no attempt is made to provide a comprehensive review of the relevant literature Three basic aspects are addressed: firstly, the localization of arterial lesions; secondly, the local hemodynamics of arterial segments with a high predilection to the development of lesions; and thirdly, the interaction of hemodynamic factors with the arterial wall The many unresolved questions, apparently conflicting experimental data and areas in need of future research on the role of fluid mechanics in atherogenesis are identified specifically
TL;DR: d-AMPH appears to inhibit reversibly MAO type A in vivo, however, using the same ‘protection protocol’, d-AM PH failed to oppose phenelzine-induced lowering of striatal DOPAC, suggesting reversible, intraneuronal MAO inhibition by d- AMPH in vivo.
TL;DR: This work proposes a new technique capable of indexing all three types of change at both individual and group levels of analysis in self-report data.
Abstract: Three conceptually different types of change that can occur with self-report data were identified by Golembiewski, Billingsley, and Yeager [1976]. We review research on this topic and propose a new technique capable of indexing all three types of change at both individual and group levels of analysis.
TL;DR: This paper examined two aspects of congressional representation: the responsiveness of House candidates to constituency opinion and the effect of candidate positions on House election outcomes, finding that constituency liberalism is strongly related to the liberalism of incumbent candidates but less so to the liberal of challengers.
Abstract: This paper examines two aspects of congressional representation: the responsiveness of House candidates to constituency opinion and the effect of candidate positions on House election outcomes. For both Democratic- and Republican-held seats, constituency liberalism (as measured by the constituency's vote for McGovern in 1972) is strongly related to the liberalism of incumbent candidates but less so to the liberalism of challengers. House election outcomes are visibly influenced by the positions of incumbent candidates but not those of nonincumbent candidates. The paper argues that elections contribute significantly to achieving congressional representation. Candidate positions are measured from a 1974 CBS survey of all major House candidates.
TL;DR: It is proved that with the exception of C4, there are no graphs of diameter 2, of maximum degree d, and with d2 vertices.
Abstract: It is well known that there are at most four Moore graphs of diameter 2, i.e., graphs of diameter 2, maximum degree d, and d2 + 1 vertices. The purpose of this paper is to prove that with the exception of C4, there are no graphs of diameter 2, of maximum degree d, and with d2 vertices.
TL;DR: This paper presents a new application of ``dagger-sampling'', for calculating the system unavailability of a large complicated system represented by a coherent fault tree using the Monte Carlo estimator.
Abstract: Reliability problems usually result in rare-event simulations, and hence direct Monte Carlo methods are extremely wasteful of computer time. This paper presents a new application of ``dagger-sampling'', for calculating the system unavailability of a large complicated system represented by a coherent fault tree. Since a small number of uniform random numbers generate a number of trials, dagger-sampling appreciably reduces computation time, and hence a large number of trials become possible for the rare-event problems. Further, dagger-sampling decreases the variance of the Monte Carlo estimator because it generates negatively correlated samples.
TL;DR: Lipid profiles of tissues of Penaeus setiferus caught at sea have shown that cholesterol is the dominant sterol and polyunsaturated fatty acids known to be essential in man comprise a significant portion of the fatty acid fraction.
TL;DR: Evidence demonstrates the probable occurrence of amphiphilic molecules in the prebiotic environment, and their self-assembly into vesicles with bilayer membranes resembling those of contemporary cells, and how lipid membrane structures could contribute to the establishment of ionic gradients and the selective concentration of organic compounds.
Abstract: In this paper we briefly review recent work on the prebiotic formation of fatty acids, glycerol, glycerol phosphates, acylglycerols, phosphatidic acids and other lipids. This evidence demonstrates the probable occurrence of such amphiphilic molecules in the prebiotic environment, and their self-assembly into vesicles with bilayer membranes resembling those of contemporary cells. The membranes are stable, osmotically active and able to maintain concentration gradients of ions and non-polar molecules. We then consider the role that such vesicles could have played in prebiotic evolution, and show how lipid membrane structures could contribute to the establishment of ionic gradients, to the selective concentration of organic compounds such as purines, and eventually to the emergence of early self-replicating systems.
TL;DR: In this paper, a bogus pipeline technique was employed to separate the self and other-deceptive components in social desirability responding and need for social approval and found that self-and otherdeceptive component were independent of each other but positively and independently related to individual differences in need for approval score.
TL;DR: In this paper, life history data as discourse are examined, and recent perspectives from psychology, linguistics and anthropology are applied to the narrative, including the background knowledge necessary to understand it, and the narrator who produced it.
Abstract: Life history data as discourse are examined, and recent perspectives from psychology, linguistics and anthropology are applied to the narrative. Each perspective illuminates some portion of the text, including its overall structure, the background knowledge necessary to understand it, and the narrator who produced it. Attention to complex ethnographic data promises to facilitate the integration of theory. [cognitive anthropology, discourse, life history, methodology, urban America]
TL;DR: A survey of recent advances in these areas and salient features of some of the more prominent studies can be found in this paper, along with a summary of the most prominent studies and their salient features.
Abstract: Recent research into the behavior of expansive clays has led to rational procedures for quantifying swell and skrinkage and differential movements in expensive subgrades. These procedures, used in conjuntion with modern numerical techniques for analyzing the static interaction of foundations and soils, have permitted the development of rational foundation design procedures that can be employed in a design office. This paper surveys recent advances in these areas and summarizes the salient features of some of the more prominent studies.
TL;DR: Comparison of 16S ribosomal RNA catalogues for many of the Rhodospirillaceae investigated by Ambler et al. and comparative analysis of several unrelated macromolecules yields essentially the same phylogenetic tree is used to compare molecular phylogenies for these bacteria.
Abstract: It is generally thought that interspecific (lateral) transfer of genes is so extensive among bacteria that it is difficult, and perhaps impossible, to determine their phylogenetic relationships. Ambler and coworkers1 reflect this in their suggestion that the relationships seen among cytochrome c sequences of the Rhodospirillaceae are merely the result of a haphazard lateral transfer of the particular gene, and give no indication of the true bacterial phylogenies. However, if comparative analysis of several unrelated macromolecules yields essentially the same phylogenetic tree, then that pattern is extremely unlikely to reflect the lateral transfer of genes2. We have also determined 16S ribosomal RNA catalogues3 for many of the Rhodospirillaceae investigated by Ambler et al. and here we use these two sets of data to compare molecular phylogenies for these bacteria.
TL;DR: In this article, Contrastive Vignette Technique (CVT) is used to predict convergent and divergent response patterns based on group membership, comparison against concurrent direct measurement of the same conceptual content area, and comparison of response patterns across and within vignettes.
Abstract: The need for indirect assessment techniques for the measurement of social attitudes is discussed, and the disappointing results of many current methodologies reviewed. Contrastive Vignette Technique (CVT), an indirect-structured methodology designed to overcome many of the shortcomings inherent in Current techniques, is presented. Three construct validation procedures were carried out in attempting to provide evidence for the value of the CVT approach in the assessment of group attitudes: Prediction of convergent and divergent response patterns based on group membership, comparison against concurrent direct measurement of the same conceptual content area, and comparison of response patterns across and within vignettes. Overall results provided support for the validity of the present approach. Of 16 directional response-pattern predictions made in the first experiment, 15 were confirmed, and the remaining prediction was in the expected direction. In the second procedure, expectations of differential response patterns were more clearly observed in CVT performance than in responses on direct scales designed to address the same content. Results of the final experiment suggested that CVT performance was consistent and transsituational, but that the effect of the evaluative context was stronger than expected. Extension and application of CVT is discussed.
TL;DR: Although the role of clays in the origin of metabolic pathways has not been demonstrated, it is possible that clays may have played a cooperative role with catalytic peptides in an intermediate stage of prebiological chemistry preceding the emergence of life on this planet.
Abstract: The ways in which clays have been utilized in studies of prebiological chemistry are reviewed, and an assessment is given of the possible role of clays in prebiological systems. The adsorption of organic molecules on clays has been demonstrated, as has the synthesis of bioorganic monomers in the presence of clays. For instance, amino acids, purines and pyrimidines have been obtained from carbon monoxide and nitric acid in the presence of clays at relatively high temperatures (250-325 C). The oligomerization of biochemical monomers, mediated by clays, has also been shown to result in the formation of polymer molecules basic to life. Clays have also been found to affect the condensation of mononucleotides to oligonucleotides.
TL;DR: In this paper, a simplified model of a polypeptide chain is described, where each residue is represented by a single interaction center and the energy of the chain and the force acting on each residue are given as a function of the residue coordinates.
Abstract: A simplified model of a polypeptide chain is described. Each residue is represented by a single interaction center. The energy of the chain and the force acting on each residue are given as a function of the residue coordinates. Terms to approximate the effect of solvent and the stabilization energy of helix formation are included. The model is used to study equilibrium and dynamical aspects of the helix–coil transition. The equilibrium properties examined include helix–coil equilibrium constants and their dependence on chain position. Dynamical properties are examined by a stochastic simulation of the Brownian motion of the chain in its solvent surroundings. Correlations in the motions of the residues are found to have an important influence on the helix–coil transition rates.
TL;DR: The data from all 3 experiments were consistent with similar data reported for human subjects and, therefore, to the extent that human data reflect the existence of sustained and transient channels, so do the monkey data.
TL;DR: In this paper, the authors report the results of 16 market experiments designed to produce measures of the effects of nonresidential land uses on the prices of nearby dwellings, each experiment consists of a sample of home sales in a homogeneous neighborhood located near a single non-residential use, e.g., industry, commercial, high-density dwellings, and highways.
TL;DR: In this paper, a perturbation analysis of the deformation and orientation of drops in shear and extensional flow fields is presented, where a more general stress boundary condition is used at the drop interface.
TL;DR: The authors present an integrative model of the reward allocation process in organizations, review previous research within the framework of the model, and suggest areas for future research, and present an integrated model for reward allocation in organizations.
Abstract: An understanding of the variables that affect managerial reward allocation decisions is vital because of the effects of such rewards on employee behavior and organizational effectiveness. We present an integrative model of the reward allocation process in organizations, review previous research within the framework of the model, and suggest areas for future research.
TL;DR: In this paper, a model is formulated in order to study the transient behavior of oil ganglion populations during immiscible displacement in oil recovery processes, which is composed of three components: a suitable model for granular porous media; a stochastic simulation method capable of predicting the expected fate (mobilization, breakup, stranding) of solitary oil ganglia moving through granular porosity; and two coupled ganglions population balance equations, one applying to moving ganglia and the other to stranded ones.
Abstract: A model is formulated in order to study the transient behavior of oil ganglion populations during immiscible displacement in oil recovery processes. The model is composed of three components: a suitable model for granular porous media; a stochastic simulation method capable of predicting the expected fate (mobilization, breakup, stranding) of solitary oil ganglia moving through granular porous media; and two coupled ganglion population balance equations, one applying to moving ganglia and the other to stranded ones. The porous medium model consists of a regular network of randomly sized unit cells of the constricted tube type. Based on this model and a mobilization-breakup criterion, computer aided simulations provide probabilistic information concerning the fate of solitary oil ganglia. Such information is required in the ganglion population balance equations, the solution of which delineates the conditions under which oil bank formation suceeds or fails. Successful oil bank formation depends on the outcome of the competition between the process of oil ganglion deterioration through breakup and stranding on one hand and the process of oil ganglion collision and coalescence on the other. The parameters entering the system of population balances are initial ganglion number concentration, average ganglion velocity, ganglion dispersion coefficients, ganglion stranding coefficient, ganglion breakup coefficient and probability of coalescence given a collision. These parameters are, in turn, functions of the porous medium geometry, capillary number, ganglion size distribution, flood velocity, oil saturation and flood composition.