Showing papers by "University of Notre Dame published in 1997"
TL;DR: This article proposed a model based upon the subordinate's psychological attributes and the organization's situational characteristics to reconcile the differences between these assumptions by proposing a model that reconciles the differences among these assumptions.
Abstract: Recent thinking about top management has been influenced by alternative models of man.1 Economic approaches to governance such as agency theory tend to assume some form of homo-economicus, which depict subordinates as individualistic, opportunistic, and self-serving. Alternatively, sociological and psychological approaches to governance such as stewardship theory depict subordinates as collectivists, pro-organizational, and trustworthy. Through this research, we attempt to reconcile the differences between these assumptions by proposing a model based upon the subordinate's psychological attributes and the organization's situational characteristics.
4,288 citations
TL;DR: In this article, the authors present a compilation of trace element data from approximately sixty published works for NIST SRM 611 and NISTSRM 613 and provide useful new working values for these reference materials.
Abstract: Microanalytical trace element techniques (such as ion probe or laser ablation ICP-MS) are hampered by a lack of well characterized, homogeneous standards. Two silicate glass reference materials produced by National Institute of Standards and Technology (NIST), NIST SRM 610 and NIST SRM 612, have been shown to be homogeneous and are spiked with up to sixty one trace elements at nominal concentrations of 500 μg g-1 and 50 μg g-1 respectively. These samples (supplied as 3 mm wafers) are equivalent to NIST SRM 611 and NIST SRM 613 respectively (which are supplied as 1 mm wafers) and are becoming more widely used as potential microanalytical reference materials. NIST however, only certifies up to eight elements in these glasses. Here we have compiled concentration data from approximately sixty published works for both glasses, and have produced new analyses from our laboratories. Compilations are presented for the matrix composition of these glasses and for fifty eight trace elements. The trace element data includes all available new and published data, and summaries present the overall average and standard deviation, the range, median, geometric mean and a preferred average (which excludes all data outside ± one standard deviation of the overall average). For the elements which have been certified, there is a good agreement between the compiled averages and the NIST data. This compilation is designed to provide useful new working values for these reference materials.
2,487 citations
TL;DR: In this article, a model for controllable fluid dampers is proposed that can effectively portray the behavior of a typical magnetorheological (MR) damper and compared with experimental results for a prototype damper.
Abstract: Semiactive control devices have received significant attention in recent years because they offer the adaptability of active control devices without requiring the associated large power sources. Magnetorheological (MR) dampers are semiactive control devices that use MR fluids to produce controllable dampers. They potentially offer highly reliable operation and can be viewed as fail-safe in that they become passive dampers should the control hardware malfunction. To develop control algorithms that take full advantage of the unique features of the MR damper, models must be developed that can adequately characterize the damper's intrinsic nonlinear behavior. Following a review of several idealized mechanical models for controllable fluid dampers, a new model is proposed that can effectively portray the behavior of a typical MR damper. Comparison with experimental results for a prototype damper indicates that the model is accurate over a wide range of operating conditions and is adequate for control design an...
1,897 citations
TL;DR: In this paper, the authors provide a concise point of departure for researchers and practitioners alike wishing to assess the current state of the art in the control and monitoring of civil engineering structures, and provide a link between structural control and other fields of control theory.
Abstract: This tutorial/survey paper: (1) provides a concise point of departure for researchers and practitioners alike wishing to assess the current state of the art in the control and monitoring of civil engineering structures; and (2) provides a link between structural control and other fields of control theory, pointing out both differences and similarities, and points out where future research and application efforts are likely to prove fruitful. The paper consists of the following sections: section 1 is an introduction; section 2 deals with passive energy dissipation; section 3 deals with active control; section 4 deals with hybrid and semiactive control systems; section 5 discusses sensors for structural control; section 6 deals with smart material systems; section 7 deals with health monitoring and damage detection; and section 8 deals with research needs. An extensive list of references is provided in the references section.
1,883 citations
01 Apr 1997
TL;DR: A new adiabatic switching paradigm is developed which permits clocked control, eliminates metastability problems, and enables a pipelined architecture.
Abstract: We describe a paradigm for computing with interacting quantum dots, quantum-dot cellular automata (QCA). We show how arrays of quantum-dot cells could be used to perform useful computations. A new adiabatic switching paradigm is developed which permits clocked control, eliminates metastability problems, and enables a pipelined architecture.
1,127 citations
TL;DR: In this paper, the authors quantified metal adsorption onto cell wall surfaces of Bacillus subtilis by applying equilibrium thermodynamics to the specific chemical reactions that occur at the water-bacteria interface.
712 citations
TL;DR: In this article, the authors proposed a model to predict the performance of new ventures based on factors that can be observed at the time of start-up, such as education, gender, race, education, and race.
Abstract: This research seeks to predict the performance of new ventures based on factors that can be observed at the time of start-up. Indicators of initial human and financial capital are considered to determine how they bear upon the probability of three possible performance outcomes: (1) failure, (2) marginal survival, or (3) high growth. Four categories of initial human and financial capital are examined. General human capital, represented here by the entrepreneur's education, gender, and race, may reflect the extent to which the entrepreneur has had the opportunity to develop relevant skills and contacts. Management know-how, embodied in the entrepreneur or available through advisors or partners, reflects management-specific skills and knowledge, without regard to the kind of business. Industry-specific know-how reflects specific experience in similar businesses. Financial capital is one of the most visible resources; it can create a buffer against random shocks and allow the pursuit of more capital-intensive strategies, which are better protected from imitation. The study utilizes a longitudinal study of 1053 new ventures, representative of all industry sectors and geographical regions. The research departs from most previous studies in considering different measures of performance (marginal survival and growth) and in considering explicitly whether the factors contributing to marginal survival differ from those contributing to high growth. It was found that measures of general human capital influenced both survival and growth (except for gender, with women-owned ventures being less likely to grow, but just as likely to survive). Management know-how variables had more limited impact. Having parents who had owned a business contributed to marginal survival, but not to growth. Number of partners contributed to growth but not to survival. Management level, prior employment in non-profit organizations or not having been in the labor force, and the use of professional advisors did not have significant effects. Industry-specific know-how contributed to both survival and growth. Amount of initial financial capital also contributed to both. The usefulness of the model is enhanced by the fact that the resource variables considered are relatively easy to assess and all can be considered at the time of start-up. Although some of the human capital variables cannot easily be changed, the benefits or risks associated with each can be assessed. In some cases, potential problems can be identified so that plans can be modified to improve prospects. Overall it appears that, using a model based upon the initial human and financial capital of the venture, it is possible to predict the performance of new ventures with some degree of confidence.
609 citations
TL;DR: In this paper, a basic cell of the quantum-dot cellular automata, a transistorless approach to computation that addresses the issues of device density, interconnection, and power dissipation, is presented.
Abstract: This paper presents an experimental demonstration of a basic cell of the quantum-dot cellular automata, a transistorless approach to computation that addresses the issues of device density, interconnection, and power dissipation. The device under study was composed of four metal dots, connected with tunnel junctions and capacitors, and operated at <50 mK. Operation was evidenced by switching of a single electron between output dots controlled by a single electron switching in input dots, demonstrating a nonlinear, bistable response.
591 citations
TL;DR: In this paper, the authors review the rapid developments which have been occurring in the area of controlled civil structures, including full-scale implementations, actuator types and characteristics, and trends toward the incorporation of more modern algorithms and technologies.
Abstract: The protection of civil structures, including their material contents and human occupants, is without doubt a worldwide priority of the most serious importance. Such protection may range from reliable operation and comfort, on the one hand, to survivability on the other. Examples of such structures leap to one's mind, and include buildings, offshore rigs, towers, roads, bridges, and pipelines. In like manner, events that cause the need for such protective measures are earthquakes, winds, waves, traffic, lightning, and-today, regrettably-deliberate acts. Indications are that control methods will be able to make a genuine contribution to this problem area, which is of great economic and social importance. In this article, we review the rapid developments which have been occurring in the area of controlled civil structures, including full-scale implementations, actuator types and characteristics, and trends toward the incorporation of more modern algorithms and technologies.
420 citations
Posted Content•
TL;DR: In this article, the authors used 947 acquisitions during 1970-1989 to find a relationship between post-acquisition returns and the mode of acquisition and form of payment and found that firms that complete stock mergers on average earn negative excess returns of -25.0 percent whereas those that complete cash tender offers earn significantly positive excess return of 61.7 percent.
Abstract: Using 947 acquisitions during 1970-1989, this paper finds a relationship between the post-acquisition returns and the mode of acquisition and form of payment. During a five-year period following the acquisition, on average, firms that complete stock mergers earn significantly negative excess returns of -25.0 percent whereas firms that complete cash tender offers earn significantly positive excess returns of 61.7 percent. Over the combined pre- and post-acquisition period, target shareholders do not earn significantly positive excess returns in stock mergers. In the top quartile of target to acquirer size ratio, target shareholders earn negative excess returns in stock mergers.
376 citations
TL;DR: In this paper, the authors examined whether investments in advanced manufacturing technologies (AMTs) such as flexible manufacturing systems (FMS), computer aided design (CAD), computer-aided manufacturing (CAM), robotics, etc., are more likely to lead to improved performance if they are supported by improvements in the manufacturing infrastructure of the company.
TL;DR: This work has identified two components released by PC-3 cells, urokinase (uPA) and free sulfhydryl donors (FSDs) that are sufficient for angiostatin generation and defines a direct mechanism for cancer-cell-mediated angiosteroid generation and permits large-scale production of bioactive angiOSTatin for investigation and potential therapeutic application.
Abstract: Angiostatin, a potent naturally occurring inhibitor of angiogenesis and growth of tumor metastases, is generated by cancer-mediated proteolysis of plasminogen. Human prostate carcinoma cells (PC-3) release enzymatic activity that converts plasminogen to angiostatin. We have now identified two components released by PC-3 cells, urokinase (uPA) and free sulfhydryl donors (FSDs), that are sufficient for angiostatin generation. Furthermore, in a defined cell-free system, plasminogen activators [uPA, tissue-type plasminogen activator (tPA), or streptokinase], in combination with one of a series of FSDs (N-acetyl-l-cysteine, d-penicillamine, captopril, l-cysteine, or reduced glutathione] generate angiostatin from plasminogen. An essential role of plasmin catalytic activity for angiostatin generation was identified by using recombinant mutant plasminogens as substrates. The wild-type recombinant plasminogen was converted to angiostatin in the setting of uPA/FSD; however, a plasminogen activation site mutant and a catalytically inactive mutant failed to generate angiostatin. Cell-free derived angiostatin inhibited angiogenesis in vitro and in vivo and suppressed the growth of Lewis lung carcinoma metastases. These findings define a direct mechanism for cancer-cell-mediated angiostatin generation and permit large-scale production of bioactive angiostatin for investigation and potential therapeutic application.
TL;DR: In this article, a steady-state fluorescence and time-resolved flash photolytic investigation of a series of covalently linked fullerene/ferrocene based donor−bridge−acceptor dyads is reported as a function of the nature of the spacer between the donor site (ferrocenes) and acceptor site (fullerene) and the dielectric constant of the medium.
Abstract: A systematic steady-state fluorescence and time-resolved flash photolytic investigation of a series of covalently linked fullerene/ferrocene based donor−bridge−acceptor dyads is reported as a function of the nature of the spacer between the donor site (ferrocene) and acceptor site (fullerene) and the dielectric constant of the medium. The fluorescence of the investigated dyads 2 (Φrel = 0.17 × 10-4), 3 (Φrel = 0.78 × 10-4), 4 (Φrel = 1.5 × 10-4), 5 (Φrel = 0.7 × 10-4), and 6 (Φrel = 2.9 × 10-4) in methylcyclohexane at 77 K were substantially quenched, relative to N-methylfulleropyrrolidine 1 (Φrel = 6.0 × 10-4), indicating intramolecular quenching of the fullerene excited singlet state. Excitation of N-methylfulleropyrrolidine revealed the immediate formation of the excited singlet state, with λmax around 886 nm. A rapid intersystem crossing (τ1/2 = 1.2 ps) to the excited triplet state was observed with characteristic absorption around 705 nm. Picosecond resolved photolysis of dyads 2−6 in toluene showed ...
TL;DR: In this article, the authors investigate the equilibrium properties of strained heteroepitaxial systems, incorporating the formation and the growth of a wetting film, dislocation-free island formation, and ripening.
Abstract: We investigate the equilibrium properties of strained heteroepitaxial systems, incorporating the formation and the growth of a wetting film, dislocation-free island formation, and ripening. The derived phase diagram provides a detailed characterization of the possible growth modes in terms of the island density, equilibrium island size, and wetting layer thickness. Comparing our predictions with experimental results we discuss the growth conditions that can lead to stable islands as well as ripening.
TL;DR: It is demonstrated that a second IL‐1R‐related Drosophila protein, 18‐Wheeler (18W), is a critical component of the humoral immune response and expression is induced in response to infection.
Abstract: Mammals and insects employ similar Rel/NF-kappaB signaling cascades in their humoral immune responses. The mammalian interleukin-1 type I receptor (IL-1R) is one way of activating this cascade. The Drosophila Toll protein, whose cytoplasmic domain shows striking similarity to that of the IL-1R, acts in the humoral antimicrobial response. Here we demonstrate that a second IL-1R-related Drosophila protein, 18-Wheeler (18W), is a critical component of the humoral immune response. 18-wheeler is expressed in the larval fat body, the primary organ of antimicrobial peptide synthesis. In the absence of the 18W receptor, larvae are more susceptible to bacterial infection. Nuclear translocation of the Rel protein Dorsal-like immunity factor (Dif) is inhibited, though nuclear translocation of another Rel protein, Dorsal, is unaffected. Induction of several antibacterial genes is reduced following infection, relative to wild-type: attacin is reduced by 95%, cecropin by 65% and diptericin by 12%. Finally, 18-wheeler (18w) expression is induced in response to infection and, in addition to the receptor form, four immune-specific transcripts and proteins are produced.
TL;DR: This paper quantified the effect of adding small quantities of liquid to a granular medium and found that adding small amounts of liquid on millimetre-scale grains dramatically increase the repose angle (the steepest stable slope that the substance can form) and allow the development of long-range correlations, or clumps.
Abstract: Any child playing on the beach knows that the physical properties of wet and dry sand are very different. Wet sand can be used to build sharp-featured sandcastles that would be unstable in dry sand. We have now quantified the effect of adding small quantities of liquid to a granular medium. Nanometre-scale layers of liquid on millimetre-scale grains dramatically increase the repose angle (the steepest stable slope that the substance can form) and allow the development of long-range correlations, or clumps.
TL;DR: It is suggested that, by increasing breastfeeding, bedsharing might be protective against SIDS, at least in some contexts, and maternal reproductive physiology could be impacted because nursing frequency affects ovulation.
Abstract: Objective. Because breastfeeding is thought to be protective against sudden infant death syndrome (SIDS), environmental or child care factors that promote breastfeeding might reduce infant vulnerability to SIDS. The effect of mother-infant bedsharing on nocturnal breastfeeding behavior was studied in 20 routinely bedsharing and 15 routinely solitary sleeping Latino mother-infant pairs when the infants were 3 to 4 months old. Methodology. All pairs were healthy and exclusively breastfeeding at night. The videotape portion of all-night laboratory polysomnographic studies was used for the analyses. For each pair, an adaptation night was followed by one night each of bedsharing and solitary sleeping. Results. The most important finding is that when tested in their usual sleeping conditions, routinely bedsharing infants breastfed approximately three times longer during the night than infants who routinely slept separately: this reflected a two-fold increase in the number of breastfeeding episodes and 39% longer episodes. Breastfeeding was also facilitated on the bedsharing night relative to the solitary night within the routinely bedsharing group: the number and total duration of breastfeeding episodes were significantly larger on the bedsharing night. Conclusions. We suggest that, by increasing breastfeeding, bedsharing might be protective against SIDS, at least in some contexts. Furthermore, maternal reproductive physiology could be impacted because nursing frequency affects ovulation. This is the first study to directly measure nocturnal breastfeeding behavior in any cultural group.
TL;DR: In this article, the authors analyzed the monthly returns on equity and mortgage real estate investment trusts (REITs) over the period July 1976 to December 1992, and found that risk premiums on equity REITs are significantly related to risk premium on a market portfolio of stocks as well as to the returns on mimicking portfolios for size and book-to-market equity factors in common stock returns.
Abstract: The monthly returns on equity and mortgage real estate investment trusts (REITs) are analyzed over the period July 1976 to December 1992. The results indicate that risk premiums on equity REITs are significantly related to risk premiums on a market portfolio of stocks as well as to the returns on mimicking portfolios for size and book-to-market equity factors in common stock returns. Mortgage REIT risk premiums are significantly related to the three stock market factors and two bond market factors in returns. Also, mortgage REIT shares underperform by an average of 6.8% per year.
TL;DR: The TF+/− embryonic lethal and the FVII−/− survival-phenotypes suggest a role for TF during embryogenesis beyond fibrin formation, which is surprising because it was expected that FVII-deficient embryos would have a similar phenotype.
Abstract: Blood coagulation in vivo is initiated by factor VII (FVII) binding to its cellular receptor tissue factor (TF)(1-4). FVII is the only known ligand for TF, so it was expected that FVII-deficient embryos would have a similar phenotype to TF-deficient embryos, which have defective vitello-embryonic circulation and die around 9.5 days of gestation(5-8), Surprisingly, we find that FVII-deficient (FVII-/-) embryos developed normally, FVII-/- mice succumbed perinatally because of fatal haemorrhaging from normal blood vessels. At embryonic day 9.5, maternal-fetal transfer of FVII was undetectable and survival of embryos did not depend on TF-FVII-initiated fibrin formation. Thus, the TF-/- embryonic lethal and the FVII-/- survival-phenotypes suggest a role for TF during embryogenesis beyond fibrin formation.
TL;DR: It is shown, using [35S]DBT radiolabelling studies, that sulphur is released in the form of inorganic sulphite, consistent with the role of DszC as a mono-oxygenase, ofDszA as an apparently unique enzyme which catalyses the reductive hydroxylation of DBTO2 leading to cleavage of the thiophene ring, and of DSzB as an aromatic sulphinic acid hydrolase.
Abstract: Summary: Rhodococcus sp. strain IGTS8 (ATCC 53968) is able to utilize dibenzothiophene (DBT) as a sole source of sulphur. The carbon skeleton of DBT is not metabolized and is conserved as 2-hydroxybiphenyl (HBP), which accumulates in the medium. This phenotype is due to the expression of the plasmid-encoded DBT-desulphurization (dsz) operon, which encodes three proteins, DszA, B and C. In this paper it is shown, using [35S]DBT radiolabelling studies, that sulphur is released in the form of inorganic sulphite. The pathway of DBT desulphurization is described in detail. In summary, DszC catalyses the stepwise S-oxidation of DBT, first to dibenzothiophene 5-oxide (DBTO) and then to dibenzothiophene 5,5-dioxide (DBTO2); DszA catalyses the conversion of DBTO2 to 2-(2′-hydroxyphenyl)benzene sulphinate (HBPSi-) and DszB catalyses the desulphination of HBPSi- to give HBP and sulphite. Studies with cell-free extracts show that DszA and DszC, but not DszB, require NADH for activity. 18O2-labelling studies show that each incorporated oxygen atom is derived directly from molecular oxygen. These results are consistent with the role of DszC as a mono-oxygenase, of DszA as an apparently unique enzyme which catalyses the reductive hydroxylation of DBTO2 leading to cleavage of the thiophene ring, and of DszB as an aromatic sulphinic acid hydrolase.
TL;DR: In this article, a non-degeneracy theory for interior point interior-point problems is proposed. But the non-egeneracy problem is not considered in this paper, and the question of solvability of a linear system arising in the implementation of the primal-dual algorithm is analyzed.
TL;DR: In this article, a short-step path-following algorithm for the convex quadratic problem on the domain, obtained as the intersection of a symmetric cone with an affine subspace, is considered.
Abstract: We provide an introduction to the theory of interior-point algorithms of optimization based on the theory of Euclidean Jordan algebras. A short-step path-following algorithm for the convex quadratic problem on the domain, obtained as the intersection of a symmetric cone with an affine subspace, is considered. Connections with the Linear monotone complementarity problem are discussed. Complexity estimates in terms of the rank of the corresponding Jordan algebra are obtained. Necessary results from the theory of Euclidean Jordan algebras are presented.
TL;DR: The data support a unified construct model for younger children and are consistent with either a dual factor or a tripartite model of depression and anxiety in older children.
Abstract: Teacher, parent, peer, and self-ratings of depression and anxiety symptoms were obtained from 280 3rd-grade and 211 6th-grade children. Confirmatory factor analysis of these multitrait-multimethod data for 3rd graders revealed low but statistically significant levels of convergent validity, high levels of method variance, and an extremely high correlation between the depression and anxiety factors, even after controlling for shared method variance. Similar analyses of 6th graders revealed slightly higher levels of convergent validity and a somewhat smaller correlation between the depression and anxiety factors. The data support a unified construct model for younger children and are consistent with either a dual factor or a tripartite model of depression and anxiety in older children.
TL;DR: The protein Wunen has two properties that allow it to use repulsion to guide the germ cells, and is expressed in the gut in a pattern that guides germ cells towards the mesoderm.
Abstract: INDrosophila, germ cells migrate in embryonic development from the lumen of the developing gut towards the overlying mesoderm, where they enter the gonads1,2. The gene wunen is responsible for guiding the germ cells early in this process3. Here we report that the protein Wunen has two properties that allow it to use repulsion to guide the germ cells. Wunen can transform a permissive cellular environment into a repulsive one, and is expressed in the gut in a pattern that guides germ cells towards the mesoderm. Wunen shows strong similarity to the enzyme type 2 phosphatidic acid phophatase(PAP2)4, suggesting that it is involved in lipid metabolism.
TL;DR: It is shown that the numbers of cells expressing eotaxin mRNA are increased within the epithelial and subepithelial layers of the nasal mucosa in individuals with chronic sinusitis, suggesting a potential role for this chemokine in the pathogenesis of allergic and nonallergic eosinophilic inflammation characterizing chronic Sinusitis and allergic rhinitis.
Abstract: Eotaxin is an eosinophil-specific chemokine associated with the recruitment of eosinophils to the site of allergic inflammation. The aims of this study were to determine the expression of eotaxin in nasal biopsies from allergic and nonallergic individuals with chronic severe sinusitis, and to examine whether the expression of this chemokine is upregulated following allergen challenge in the nasal mucosa of patients with allergic rhinitis. We also undertook to phenotype of inflammatory cells within the submucosa expressing eotaxin mRNA. Nasal turbinate tissue from 16 individuals with allergic or nonallergic chronic sinusitis and 10 normal controls were examined for the presence of eotaxin mRNA and immunoreactivity by in situ hybridization and immunocytochemistry. The numbers of cells expressing eotaxin mRNA were also determined after either allergen or diluent challenge in atopic subjects with a history of allergic rhinitis. There was a constitutive expression of eotaxin-immunoreactivity and the presence of eotaxin mRNA-positive cells in nasal biopsies from normal individuals. Compared with normal controls, the numbers of cells expressing eotaxin mRNA and protein were significantly increased in both allergic and nonallergic sinusitis (P < 0.001). Eotaxin mRNA was expressed by nasal epithelial cells and primarily colocalized to CD68-positive macrophages within the subepithelium. In subjects with allergic rhinitis, allergen challenge markedly increased the numbers of cells expressing eotaxin mRNA and immunoreactivity in the epithelial and subepithelial cell layers (P < 0.05). This could be largely attributed to a local increase in eotaxin production within the nasal tissues. The results of this study demonstrate the constitutive expression of eotaxin and show that the numbers of cells expressing eotaxin mRNA are increased within the epithelial and subepithelial layers of the nasal mucosa in individuals with chronic sinusitis. Furthermore, allergen challenge of the nasal mucosa in atopic subjects results in a local upregulation of eotaxin expression. These data suggest a potential role for this chemokine in the pathogenesis of allergic and nonallergic eosinophilic inflammation characterizing chronic sinusitis and allergic rhinitis.
TL;DR: In this paper, preferential erosion during ion sputtering can lead to a physical phenomenon reminiscent of surface diffusion, what we call effective surface diffusion (ESD), that does not imply mass transport along the surface and is independent of the temperature.
Abstract: Ion bombardment is known to enhance surface diffusion and affect the surface morphology. Here we demonstrate that preferential erosion during ion sputtering can lead to a physical phenomenon reminiscent of surface diffusion, what we call effective surface diffusion (ESD), that does not imply mass transport along the surface and is independent of the temperature. We calculate the ion-induced ESD constant and its dependence on the ion energy, flux and angle of incidence, showing that sputtering can both enhance and suppress surface diffusion. The influence of ion-induced ESD on ripple formation and roughening of ion-sputtered surfaces is discussed and summarized in a morphological phase diagram.
Abstract: Results of flow visualization, hot wire, and base pressure measurements were conducted for an investigation of the near wake of a circular cylinder at subcritical Reynolds numbers between 2700 to 46000. A base mounted splitter plate allowed for the modification of the formation region characteristics without disrupting the normal Karman shedding. The results provide an explanation for the non-linearity in the relationship between shedding frequency and splitter plate length and extend the previous investigations of Roshko (1954), Gerrard (1966) and Apelt et al. (1973). In addition to the nominal 2-D configurations, a sinuous trailing edge splitter plate, cylinder taper, and shear flow were incorporated to study the effects of mild 3-dimensionality. A strong spanwise coherence was found to exist in the formation region. A superposition principle was discovered which showed that certain 3-D geometry and flow configurations could be combined to produce a nominal 2-D wake.
01 Sep 1997
TL;DR: Three MultiObjective Collaborative Optimization (MOCO) strategies are developed, reviewed and implemented in a comparative study to provide an in depth comparison of different MOCO strategies available to system designers.
Abstract: This investigation focuses on the development of modifications to the Collaborative Optimization (CO) approach to multidisciplinary systems design, that will provide solution capabilities for multiobjective problems. The primary goal of this paper is to provide a comprehensive overview and development of mathematically rigorous optimization strategies for Multiobjective Collaborative Optimization (MOCO). Collaborative Optimization strategies provide design optimization capabilities to discipline designers within a multidisciplinary design environment. To date these CO strategies have primarily been applied to system design problems which have a single objective function. Recent investigations involving multidisciplinary design simulators have reported success in applying CO to multiobjective system design problems. In this research three MultiObjective Collaborative Optimization (MOCO) strategies are developed, reviewed and implemented in a comparative study. The goal of this effort is to provide an in depth comparison of different MOCO strategies available to system designers. Each of the three strategies makes use of parameter sensitivities within multilevel solution strategies. In implementation studies, each of the three MOCO strategies is effective in solving a multiobjective multidisciplinary systems design problem. Results indicate that these MOCO strategies require an accurate estimation of parameter sensitivities for successful implementation. In each of the three MOCO strategies these parameter sensitivities are obtained using post-optimality analysis techniques.
TL;DR: In this paper, a review of recent achievements in heavy-quark theory is presented, focusing on those aspects that either did not attract enough attention or cause heated debates in the current literature.
Abstract: ▪ Abstract Recent achievements in heavy-quark theory are critically reviewed. The emphasis is put on those aspects that either did not attract enough attention or cause heated debates in the current literature. Among other topics we discuss (a) basic parameters of the heavy-quark theory; (b) a class of exact QCD inequalities; (c) new heavy quark sum rules; (d) the virial theorem; (e) applications (|Vcb| from the total semileptonic width and from the B → D* transition at zero recoil). In some instances new derivations of previously known results are given, or new aspects addressed. In particular, we dwell on the exact QCD inequalities. Furthermore, a toy model is considered that may shed light on the controversy regarding the value of the kinetic energy of heavy quarks obtained by different methods.
TL;DR: The authors addressed the myth that children will be able to comprehend a text simply because they can decode words in it and provided evidence to support the claim that developing readers benefit from decoding words in text.
Abstract: This article addresses the myth that children will be able to comprehend a text simply because they can decode words in it. Evidence is provided to support the claim that developing readers benefit...