Showing papers by "Lehigh University published in 1992"
TL;DR: Some initial production priming explorations are reported that support the hypothesis that lemmas are buffered in longer utterances before they are phonologically specified, and a reconciliation of modular and interactive accounts of these stages is suggested.
616 citations
TL;DR: In this paper, search heuristics are developed for generic sequencing problems with emphasis on job shop scheduling, and two methods are proposed, both of which are based on novel definitions of solution spaces and of neighborhoods in these spaces.
Abstract: In this paper search heuristics are developed for generic sequencing problems with emphasis on job shop scheduling. The proposed methods integrate problem specific heuristics common to Operations Research and local search approaches from Artificial Intelligence in order to obtain desirable properties from both. The applicability of local search to a wide range of problems, and the incorporation of problem-specific information are both properties of the proposed algorithms. Two methods are proposed, both of which are based on novel definitions of solution spaces and of neighborhoods in these spaces. Applications of the proposed methodology are developed for job shop scheduling problems, and can be easily applied with any scheduling objective. To demonstrate effectiveness, the method is tested on the job shop scheduling problem with the minimum makespan objective. Encouraging results are obtained.
520 citations
TL;DR: In this article, a review of hydrogen interactions with imperfections in crystalline metals and semiconductors is presented, focusing on mechanistic experiments and theoretical advances contributing to predictive understanding.
Abstract: Hydrogen interactions with imperfections in crystalline metals and semiconductors are reviewed. Emphasis is given to mechanistic experiments and theoretical advances contributing to predictive understanding. Important directions for future research are discussed.
427 citations
Book•
01 Jan 1992TL;DR: The standard geometric codes are presented, followed by a list of recommended designs and some examples of how these designs might be implemented in the real world.
Abstract: Algebraic coding theory has in recent years been increasingly applied to the study of combinatorial designs. This book gives an account of many of those applications together with a thorough general introduction to both design theory and coding theory - developing the relationship between the two areas. The first half of the book contains background material in design theory, including symmetric designs and designs from affine and projective geometry, and in coding theory, coverage of most of the important classes of linear codes. In particular, the authors provide a new treatment of the Reed-Muller and generalized Reed-Muller codes. The last three chapters treat the applications of coding theory to some important classes of designs, namely finite planes, Hadamard designs and Steiner systems, in particular the Witt systems. The book is aimed at mathematicians working in either coding theory or combinatorics - or related areas of algebra. The book is, however, designed to be used by non-specialists and can be used by those graduate students or computer scientists who may be working in these areas.
374 citations
TL;DR: In this paper, the authors applied pyridine as a method for studying the acidic properties of niobium pentoxide supported on silica, magnesia, alumina, titania, and zirconia.
331 citations
TL;DR: The motivation for ApEn development is provided, and the superiority of ApEn to the K-S entropy for statistical application, and for discrimination of both correlated stochastic and noisy deterministic processes is indicated.
Abstract: ApEn, approximate entropy, is a recently developed family of parameters and statistics quantifying regularity (complexity) in data, providing an information-theoretic quantity for continuous-state processes. We provide the motivation for ApEn development, and indicate the superiority of ApEn to the K-S entropy for statistical application, and for discrimination of both correlated stochastic and noisy deterministic processes. We study the variation of ApEn with input parameter choices, reemphasizing that ApEn is a relative measure of regularity. We study the bias in the ApEn statistic, and present evidence for asymptotic normality in the ApEn distributions, assuming weak dependence. We provide a new test for the hypothesis that an underlying time-series is generated by i.i.d. variables, which does not require distribution specification. We introduce randomized ApEn, which derives an empirical significance probability that two processes differ, based on one data set from each process.
238 citations
TL;DR: The results of the laboratory study presented in this article indicate that electrokinetic enhancement of contaminant transport in soils is a viable technology; development of this technology for wide range of applications hinges upon better understanding of the transient chemical and physical processes during application of current through soil/contaminant systems.
Abstract: The electrokinetic process is an emerging technology for in situ soil decontamination, in which chemical species, both ionic and nonionic are transported to an electrode site in soil. These products are subsequently removed from the ground via collection systems engineered for each specific application. Electrokinetics refer to movement of water, ions and charged particles relative to one another under the action of an applied direct current electric field. In a porous compact matrix of surface charged particles such as soil, the ion containing pore fluid may be made to flow to collection sites under the applied field.
The work presented here describes part of the effort undertaken to investigate electrokinetically enhanced transport of soil contaminants in synthetic systems. The results of the laboratory study presented here indicate that electrokinetic enhancement of contaminant transport in soils is a viable technology; development of this technology for wide range of applications hinges upon better understanding of the transient chemical and physical processes during application of current through soil/contaminant systems.
237 citations
TL;DR: This paper summarizes the developments in the applications of aqueous two-phase systems to biotechnology by reviewing the phase diagram and its characteristics, fundamentals of biomolecule partition, large-scale and multi-stage aqueously two- phase biomolecules purification, and extractive bioconversions.
Abstract: Over the past-thirty years, aqueous polymer two-phase technology has evolved, both experimentally and theoretically, into a separation science with many useful applications in biomolecule purification and bioconversion. This paper summarizes the developments in the applications of aqueous two-phase systems to biotechnology. The main topics to be considered are the phase diagram and its characteristics, fundamentals of biomolecule partition, large-scale and multi-stage aqueous two-phase biomolecule purification, and extractive bioconversions. The first topic involves a discussion of the thermodynamics of aqueous polymer two-phase formation and how it is influenced by such factors as polymer molecular weight and concentration, temperature, and salt type and concentration. Next, the theoretical and experimental aspects of biomolecule partition in aqueous two-phase systems will be discussed in light of the factors which influence biomolecule partition: polymer concentration and molecular weight; temperature; salt type and concentration; the addition of charged, hydrophobic and affinity derivatives. Having reviewed the fundamentals of phase diagram formation and biomolecule partition, the next two topics are applications of aqueous two-phase technology. The first set of applications involve the large-scale extraction of proteins using one to three equilibrium stages and multi-stage purifications using countercurrent distribution, liquid-liquid partition chromatography and continuous countercurrent chromatography. The second application, and very promising area for future aqueous two-phase technology, is the extractive bioconversion which permits the simultaneous production and purification of a biomolecule.
183 citations
TL;DR: In this paper, the authors present an approach to designing multiphase microstructures and laminar composites with enhanced structural reliability based on current work on various alumina-based ceramics as well as zirconia-, silicon nitride-, and silicon carbide-containing materials.
Abstract: Duplex (two-phase) microstructures and laminar composites offer some unique opportunities for improving the room-temperature mechanical reliability (e.g., flaw tolerance) and the high-temperature microstructural stability (e.g., resistance to grain growth and creep damage) of structural ceramic materials. Examples illustrating the approach to designing novel multiphase microstructures and laminar composites with enhanced structural reliability are given. These are based on current work on various alumina-based ceramics as well as zirconia-, silicon nitride-, and silicon carbide-containing ceramics. Critical issues and areas for future work are discussed.
182 citations
TL;DR: In this article, Baier called for a "marriage" of the old male and newly articulated female moral wisdom to produce a new 'cooperative' moral theory that harmonize justice and care.
Abstract: In her provocative discussion of the challenge posed to the traditional impartialist, justice-focused conception of morality by the new-wave care perspective in ethics, Annette Baier calls for 'a "marriage" of the old male and newly articulated female moral wisdom/ to produce a new 'cooperative' moral theory that 'harmonize[s] justice and care'2 1 want in this paper to play matchmaker, proposing one possible conjugal bonding: a union of two apparently dissimilar modes of what Nel
TL;DR: This article conducted four experiments testing whether function is the primary determinat of membership in artifact categories and found that some objects that do not possess the function associated with a category are excluded from category membership, and some objects are still considered to belong to the category.
TL;DR: In this article, the optimum conditions for achieving dense and uniform microstructures by conventional ceramic processing are given in detail, and the SiC particles were found to strongly inhibit grain growth of the Al 2 O 3 matrix.
Abstract: Composites consisting of Al 2 O 3 + 5 vol.% 0·15 μm SiC particles were prepared by pressureless sintering. The optimum conditions for achieving dense and uniform microstructures by conventional ceramic processing are given in detail. The SiC particles were found to strongly inhibit grain growth of the Al 2 O 3 matrix. Densification was also significantly retarded by these ultra-fine particles, and possible explanations for this behavior are discussed.
TL;DR: In this paper, a method for interpreting the Raman spectra of bismuth oxides is presented, which relies on empirical relations between the bond lengths, bond strength, and Raman stretching frequencies.
TL;DR: Rosetans had a lower mortality rate from myocardial infarction over the course of the first 30 years, but it rose to the level of Bangor's following a period of erosion of traditionally cohesive family and community relationships.
Abstract: OBJECTIVES. Earlier studies found striking differences in mortality from myocardial infarction between Roseto, a homogeneous Italian-American community in Pennsylvania, and other nearby towns between 1955 and 1965. These differences disappeared as Roseto became more "Americanized" in the 1960s. The present study extended the comparison over a longer period of time to test the hypothesis that the findings from this period were not due to random fluctuations in small communities. METHODS. We examined death certificates for Roseto and Bangor from 1935 to 1985. Age-standardized death rates and mortality ratios were computed for each decade. RESULTS. Rosetans had a lower mortality rate from myocardial infarction over the course of the first 30 years, but it rose to the level of Bangor's following a period of erosion of traditionally cohesive family and community relationships. This mortality-rate increase involved mainly younger Rosetan men and elderly women. CONCLUSIONS. The data confirmed the existence of co...
TL;DR: In this paper, the same surface vanadium oxide species is present on all the titania supports irrespective of the crystal structure of the bulk titania phase, and the structure-reactivity studies of the different vanadia-titania catalysts suggest that the specific vanadium phase is not a critical parameter in determining the physical or chemical nature of the surface vanadia phase.
Abstract: Different phases of titania were prepared and used to support ca. 1 wt.-% V 2 O 5 . The different titania phases prepared were: anatase (A22), rutile (R28), brookite (BT110) and B-phase (B18). Physical characterization of the various vanadia-titania catalysts was performed using X-ray photoelectron spectroscopy (XPS), in situ Raman and 51 V solid state nuclear magnetic resonance (NMR) spectroscopy. The XPS results reveal that the all the catalysts contain various levels of impurities. In situ dehydration Raman shows, for all the samples, the stretching vibration of the terminal VzO bond at ca. 1030 cm −1 . Solid state 51 V NMR spectra of all the samples in the dehydrated state show basically the same powder pattern with a peak maximum around −660 to −670 ppm. The combined Raman and NMR results indicate that the same surface vanadium oxide species is present on all the titania supports irrespective of the crystal structure of the bulk titania phase. Partial oxidation of methanol show similar activity and selectivity for the various vanadia-titania catalysts. The reaction selectivity was primarily to formaldehyde and methyl formate (92–96%). The turnover number for methanol oxidation was essentially the same for all the vanadia-titania catalysts and ranged from 1.4 to 2.8 s −1 . These results indicate that the type of titania phase used as the support is not critical for partial oxidation over vanadia-titania catalysts as long as other parameters (e.g. surface impurities ) are similar. Thus, the structure-reactivity studies of the different vanadia-titania catalysts suggest that the specific titania phase is not a critical parameter in determining the physical or chemical nature of the surface vanadia phase.
TL;DR: Particle nucleation in styrene microemulsions was found to take place throughout the polymerization as indicated by measurements of the particle number as a function of conversion as mentioned in this paper, which was used to explain the experimental findings although homogeneous nucleation and coagulation during polymerization were not completely ruled out.
Abstract: Particle nucleation in the polymerization of styrene microemulsions was found to take place throughout the polymerization as indicated by measurements of the particle number as a function of conversion. A mechanism based on the nucleation in the microemulsion droplets was proposed to explain the experimental findings although homogeneous nucleation and coagulation during polymerization were not completely ruled out. A thermodynamic model was developed to simulate the partitioning of monomer in the different phases during polymerization. The model predicts that the oil cores of the microemulsion droplets were depleted early in the polymerization (4% conversion). Due to the high monomer/polymer swelling ratio of the polymer particles, most of the monomer resides in the polymer particles during polymerization. The termination of chain growth inside the polymer particles was attributed to the chain transfer reaction to monomer. The low n (less than 0.5) of the microemulsion system was attributed to the fast exit of monomeric radicals.
TL;DR: The Raman spectroscopic studies reveal that the surface molybdenum oxide species under ambient conditions, wet and calcined, are hydrated and essentially in an aqueous medium as mentioned in this paper.
TL;DR: In this paper, the pore diameters of these porous polymer particles were on the order of 1000 A with pore volumes up to 0.9 mL/g and specific surface areas up to 200 m2/g.
Abstract: Monodisperse porous polymer particles in the size range of 10 μm in diameter were prepared via seeded emulsion polymerization. Linear polymer (polystyrene seed) or a mixture of linear polymer and solvent or nonsolvent were used as inert diluents. The pore diameters of these porous polymer particles were on the order of 1000 A with pore volumes up to 0.9 mL/g and specific surface areas up to 200 m2/g. The physical features of the porous polymer particles depended on the diluent type and the crosslinker content, as well as the molecular weight of polymer seed particles. By varying the molecular weight of the linear polymer, monodisperse porous polymer particles with different pore size distribution could be synthesized. Polymer seed with a low degree of crosslinking instead of linear polymer could also be used to prepare monodisperse porous polymer particles with smaller pore volume and pore size.
TL;DR: In this paper, the effect of ligand concentration on both equilibrium and fixed-bed adsorption has been studied for three model proteins on dye-ligand adsorbents, and it was found that binding capacity was approximately proportional to immobilized dye concentration.
TL;DR: In this paper, the authors have encountered a low-frequency increase in the charge recombined per cycle, which they attribute to the charging and discharging of traps located within a tunneling distance of the Si-SiO/sub 2/ interface.
Abstract: In studies of MOS devices with the charge pumping technique, the authors have encountered a low-frequency increase in the charge recombined per cycle, which they attribute to the charging and discharging of traps located within a tunneling distance of the Si-SiO/sub 2/ interface, ie, near-interface oxide traps MOS devices subjected to ionizing radiation as well as ultrathin tunnel oxide polysilicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile memory devices possess a high density of near-interface oxide traps When the charge recombined per cycle is examined as a function of frequency, a breakpoint is observed at a particular frequency with an inverse equivalent to a trap-to-trap tunneling time constant >
TL;DR: In this paper, the authors used alumina + 20 vol% aluminum titanate (AAT20) for both the surface layer and the bulk material for a laminated composite construction of a high-toughness body.
Abstract: Adding aluminum titanate to alumina can result in dramatic improvements in toughness and R-curve properties. However, the improved toughness is offset by a significant reduction in strength at small flaw sizes. This problem can be overcome through the use of a laminated composite construction. By placing a thin layer of high-strength material on the surface of a high-toughness body, the toughness and flaw tolerance of the body material can be maintained without sacrificing small flaw strength. In this study, alumina + 20 vol% aluminum titanate (AAT20) was used for both the surface layer and the bulk material. The surface material was a homogeneous, fine-grained mixture of the two phases, while the bulk was an inhomogeneous mixture having a bimodal grain structure. In monolithic form, the homogeneous AAT20 displays a nearly P−1/3 indentation strength response, and the inhomogeneous material displays a flat strength response, indicative of R-curve behavior. The trilayer material shows a composite indentation strength response, with high strength throughout the entire range of starting flaw sizes. A method for predetermining the optimum surface layer thickness is presented. The processing and mechanical properties of these materials will be discussed.
TL;DR: In this paper, the structure of Re2O7/Al2O3, ReO4 ion in aqueous solution, independent of coverage or support type was determined by TPR as a function of coverage and support type.
TL;DR: In this article, the authors introduce four types of constraints on what can be constructed: what the constructed systems are about, the representational relationship itself, the nature of the systems being constructed, and the process of construction itself.
TL;DR: Methods for the estimation of the intraparticle diffusivity in polymer gels have been developed and were applied to the diffusion of seven model proteins in agarose particles, resulting in a correlation based on the restricted diffusion model of Ogston et al. (1973) and Cukier (1984).
Abstract: The diffusion of proteins in polymer matrices is an important step in the adsorptive and chromatographic processes used for protein purification, as it is often rate-limiting. Methods for the estimation of the intraparticle diffusivity in polymer gels have been developed and were applied to the diffusion of seven model proteins in agarose particles. The intraparticle diffusivity was not affected by particle diameter. A correlation based on the restricted diffusion model of Ogston et al. (1973) and Cukier (1984) has been proposed. This correlation allows the estimation of protein diffusivity in these matrices based on the molecular weight of the protein and the polymer concentration.
TL;DR: In this article, the kinetics of the emulsifier-free emulsion copolymerization of styrene and sodium styrene sulfonate have been examined over a range of comonomer compositions.
Abstract: The kinetics of the emulsifier-free emulsion copolymerization of styrene and sodium styrene sulfonate have been examined over a range of comonomer compositions. The rate of polymerization was found to increase dramatically in the presence of small amounts of sodium styrene sulfonate. This increase is attributed to the increased number of particles formed when sodium styrene sulfonate was present and to a gel effect enhanced by ion association. At low concentrations of functional comonomer, where a monodisperse product was obtained, a homogeneous nucleation mechanism of particle generation is proposed. At higher concentrations, broader and then bimodal size distributions were obtained, and this is ascribed to significant aqueous phase polymerization of sodium styrene sulfonate. The water-soluble homopolymer is supposed to act as a locus of polymerization. The occurrence of this aqueous phase side reaction and the generation of secondary particles makes impossible the preparation of highly sulfonated polystyrene latexes by batch or seeded batch emulsion copolymerization.
TL;DR: This article used voting data to shed light on the extent to which referenda constrain spending and found that large school districts behave more like "budget maximizers" than do small districts, where proposals appear more in line with median voter demands.
TL;DR: In this paper, the molecular structure of the two-dimensional chromium oxide overlayer on the silica support at different chromium oxides contents has been investigated by in situ Raman spectroscopy.
TL;DR: In this article, the authors describe the mechanism of formation of porous polymer particles during the copolymerization and solvent extraction stages, in which porosity was a consequence of phase separation in the presence of diluents.
Abstract: Monodisperse porous styrene-divinylbenzene copolymer particles were prepared via seeded emulsion polymerization using a mixture of linear polymer (polystyrene seed) and non-solvent as inert diluent. Experimental evidence was presented to describe the mechanism of formation of porous polymer particles during the copolymerization and solvent extraction stages, in which porosity was a consequence of phase separation in the presence of diluents. Pore structure formation was investigated by changes in copolymerization kinetics, gel content, crosslinking density, particle morphology, surface area, pore volume, and pore size distribution. The process of copolymerization was presented, based on the concepts of production, agglomeration, and fixation of the interior gel microspheres of polymer particles. A portion of linear polymer used as diluent was found to participate in the network structure while the porous matrix was built-up. The influence of the removal of the linear polymer from the matrix pores during the solvent extraction process on the porous structure was also discussed.
TL;DR: In conclusion, implants of T or TP were effective in restoring ultrasonic mating vocalization when placed into the MPO and MPO implants ofT and TP were also effective in stimulating urine marking, although VMH and AHA implants also showed some effectiveness.