cssi/SciSciGPT-SciSciNet huggingface dataset:
Information spillovers around seasoned equity offerings

Abstract We examine information spillovers in the context of seasoned equity offerings (SEOs). Rival firms react significantly positively (0.26%) to primary SEO announcements, indicative of a competitive effect, but negatively (− 0.35%) to secondary share announcements, which is evidence of a contagion effect. Consistent with the view that primary equity offerings signal favorable industry prospects because firms presumably issue new shares to invest in profitable projects, we find that the rival response is positively related to analysts' EPS growth forecasts. However, when insiders are selling their shares through a secondary offer, this may suggest overvaluation and thus negatively impacts rival firms. Consistent with this view, we find when VCs sell through a secondary offerings, rivals experience a more significant negative reaction. We find rival firms are more likely to follow their peers and conduct a primary SEO if the market reacts favorably to their peer's SEO announcement. Finally, rival firms outperform secondary share issuers of equity, but not primary share issuers. Collectively, the findings support the view that insiders take advantage of windows of opportunity when they sell their own shares, but not when they raise capital for investing purposes.
Transformations for write-all-with-collision model

Dependable properties such as self-stabilization are crucial requirements in sensor networks. One way to achieve these properties is to utilize the vast literature on distributed systems where such self-stabilizing algorithms have been designed. Since these existing algorithms are designed in read/write model (or variations thereof), they cannot be directly applied in sensor networks. For this reason, we consider a new atomicity model, write all with collision (WAC), that captures the computations of sensor networks and focus on transformations from read/write model to WAC model and vice versa. We show that the transformation from WAC model to read/write model is stabilization preserving, and the transformation from read/write model to WAC model is stabilization preserving for timed systems. In the transformation from read/write model to WAC model, if the system is untimed (asynchronous) and processes are deterministic then under reasonable assumptions, we show that (1) the resulting program in WAC model can allow at most one process to execute, and (2) the resulting program in WAC model cannot be stabilizing.
Rhodium(I)-catalyzed N-CN bond cleavage: intramolecular β-cyanation of styrenes.

We report herein the first example of intramolecular cyanation of a styrene by a rhodium(I)-catalyzed N–CN cleavage reaction. Substituents on the arenes or the styrene alpha-position are tolerated. Our results demonstrate that alkene cyanation can indeed be atom economical.
The generic isometry and measure preserving homeomorphism are conjugate to their powers

It is known that there is a comeagre set of mutually conjugate measure preserving homeomorphisms of Cantor space equipped with the coinflipping probability measure, i.e., Haar measure. We show that the generic measure preserving homeomorphism is moreover conjugate to all of its powers. It follows that the generic measure preserving homeomorphism extends to an action of (Q, +) by measure preserving homeomorphisms, and, in fact, to an action of the locally compact ring A of finite adeles. Similarly, S. Solecki has proved that there is a comeagre set of mutually conjugate isometries of the rational Urysohn metric space. We prove that these are all conjugate with their powers and therefore also embed into Q-actions. In fact, we extend these actions to actions of A as in the case of measure preserving homeomorphisms. We also consider a notion of topological similarity in Polish groups and use this to give simplified proofs of the meagreness of conjugacy classes in the automorphism group of the standard probability space and in the isometry group of the Urysohn metric space.
Catalytic asymmetric synthesis of highly substituted pyrrolizidines

A catalytic asymmetric double (1,3)-dipolar cycloaddition reaction has been developed. Using a chiral silver catalyst, enantioenriched pyrrolizidines can be prepared in one flask from inexpensive, commercially available starting materials. The pyrrolizidine products contain a variety of substitution patterns and as many as six stereogenic centers.
Sixty Billion Gallons by 2030: Economic and Agricultural Impacts of Ethanol and Biodiesel Expansion

Agriculture is well positioned as a feedstock source because the fuels can be utilized with current engine technologies and are compatible with the current distribution infrastructure. Commercialization of cellulosic to ethanol technology will enable fuels to be derived from a diverse portfolio of feedstocks from numerous regions of the country. The levels of ethanol production analyzed are 10, 30, and 60 billion gallons of ethanol annually by 2010, 2020 and 2030, respectively. Impacts of producing 1 billion gallons of biodiesel production by 2012 and 1.6 billion gallons by 2030 are also projected. Overall, for the period 2007 to 2030, the estimated accumulated gains in net farm income are over $210 billion; and the accumulated potential savings in government payments are estimated to be $150 billion. Due to the geographic decentralization of the production of feedstock, economic gains are projected to accrue to the majority of regions of the country. Significant expansion beyond 60 billion gallons per year would likely require expansion of the region suitable for the production of bioenergy crops, ability to convert other pastureland (beyond cropland in pasture) into energy crops; allowing CRP acreage to be used in feedstock production, increasing short-rotation wood crops in the Northeast and Northwest regions, increased yields above those assumed in the analysis, and/or increasing the efficiency of cellulosic conversion. Further research should examine the agricultural, environmental, and economic impacts of one or more these factors changing.(This abstract was borrowed from another version of this item.)
Enantioselective synthesis of the 6,8-dioxabicyclo-[3.2.1]octane skeleton by asymmetric dihydroxylation

Abstract Sharpless asymmetric dihydroxylation (AD) of 6-hepten-2-one with AD-mix-α® followed by acidification gives (1S,SR)-5-methyl- 6,8-dioxabicyclo[3.2.1]octane in moderate ee. This methodology defines a two-pot enantioselective construction of the (−)- frontalin and brevicomin skeleton from the corresponding 2-alkyl-1,3-dithiane and 5-bromo-1-hexene derivatives.
Multivariate Negative Binomial Models for Insurance Claim Counts

Abstract It is no longer uncommon these days to find the need in actuarial practice to model claim counts from multiple types of coverage, such as the ratemaking process for bundled insurance contracts. Since different types of claims are conceivably correlated with each other, the multivariate count regression models that emphasize the dependency among claim types are more helpful for inference and prediction purposes. Motivated by the characteristics of an insurance dataset, we investigate alternative approaches to constructing multivariate count models based on the negative binomial distribution. A classical approach to induce correlation is to employ common shock variables. However, this formulation relies on the NB-I distribution which is restrictive for dispersion modeling. To address these issues, we consider two different methods of modeling multivariate claim counts using copulas. The first one works with the discrete count data directly using a mixture of max-id copulas that allows for flexible pair-wise association as well as tail and global dependence. The second one employs elliptical copulas to join continuitized data while preserving the dependence structure of the original counts. The empirical analysis examines a portfolio of auto insurance policies from a Singapore insurer where claim frequency of three types of claims (third party property damage, own damage, and third party bodily injury) are considered. The results demonstrate the superiority of the copula-based approaches over the common shock model. Finally, we implemented the various models in loss predictive applications.
Manufacturing strategy implementation and cost management systems effectiveness

The fit between manufacturing strategy and the use of cost management systems that could effectively support a firm's information needs in strategic and operational decision-making is prerequisite for a firm's ability to attain desired objectives in its value chain. The primary purpose of this study is to examine the relationship between the use of just-in-time and electronic data interchange systems, as an important dimension of a firm's manufacturing strategy, and the perceptions of top financial officers about the effectiveness of cost management systems in supporting strategic and operational decision needs. The results for the research hypothesis, which was examined using a sample of 604 manufacturing organizations in the USA, provided some support for the argument that perceptions of effectiveness of a firm's CMS can be a valid indicator of how well is the CMS designed to support strategic and operational decision needs that are necessary for the implementation of a firm's manufacturing strategy.
An affinity for affine quantum gravity

The main principle of affine quantum gravity is the strict positivity of the matrix $$\{ \hat g_{ab} (x)\} $$ composed of the spatial components of the local metric operator. Canonical commutation relations are incompatible with this principle, and they can be replaced by noncanonical, affine commutation relations. Due to the partial second-class nature of the quantum gravitational constraints, it is advantageous to use the projection operator method, which treats all quantum constraints on an equal footing. Using this method, enforcement of regularized versions of the gravitational constraint operators is formulated quite naturally as a novel and relatively well-defined functional integral involving only the same set of variables that appears in the usual classical formulation. Although perturbatively nonrenormalizable, gravity may possibly be understood nonperturbatively from a hard-core perspective that has proved valuable for specialized models.
On the abundance of non-cometary HCN on Jupiter

Using one-dimensional thermochemical/photochemical kinetics and transport models, we examine the chemistry of nitrogen-bearing species in the Jovian troposphere in an attempt to explain the low observational upper limit for HCN. We track the dominant mechanisms for interconversion of N2–NH3 and HCN–NH3 in the deep, high-temperature troposphere and predict the rate-limiting step for the quenching of HCN at cooler tropospheric altitudes. Consistent with some other investigations that were based solely on time-scale arguments, our models suggest that transport-induced quenching of thermochemically derived HCN leads to very small predicted mole fractions of hydrogen cyanide in Jupiter's upper troposphere. By the same token, photochemical production of HCN is ineffective in Jupiter's troposphere: CH4–NH3 coupling is inhibited by the physical separation of the CH4 photolysis region in the upper stratosphere from the NH3 photolysis and condensation region in the troposphere, and C2H2–NH3 coupling is inhibited by the low tropospheric abundance of C2H2. The upper limits from infrared and submillimetre observations can be used to place constraints on the production of HCN and other species from lightning and thundershock sources.
An enantioselective total synthesis of (+)- and (-)-saudin. Determination of the absolute configuration.

A short efficient enantioselective synthesis of both (+)- and (−)-saudin, a naturally occurring hypoglycemic diterpene, is described. This synthesis establishes the absolute configuration of natural (−)-saudin for the first time. The key steps include the enantioselective construction of a dimethyl Hagemann's ester by an asymmetric Michael reaction and establishment of the key 1,3 disposed quaternary centers by means of a novel Ti(IV) promoted Claisen rearrangement. The assembly of the polycyclic ketal skeleton was likely under kinetic control proceeding via formation of the C1oxygen−C7 bond through an oxonium ion intermediate in the final stage.
The higher connectivity of intersections of real quadrics

Abstract A linear system of real quadratic forms defines a real projective variety. The real non-singular locus of this variety (more precisely of the underlying scheme) has a highly connected double cover as long as each non-zero form in the system has sufficiently high Witt index.
MAGNETIC PROPERTIES OF YOUNG STARS IN THE TW HYDRAE ASSOCIATION

We present an analysis of infrared echelle spectra of five stars in the TW Hydrae Association (TWA). We model the Zeeman broadening in four magnetic-sensitive Ti I lines near 2.2 μm and measure the value of the photospheric magnetic field averaged over the surface of each star. To ensure that other broadening mechanisms are properly taken into account, we also inspect several magnetically insensitive CO lines near 2.3 μm and find no excess broadening above that produced by stellar rotation and instrumental broadening, providing confidence in the magnetic interpretation of the width of the Ti I lines. We then utilize our results to test the relationship between stellar magnetic flux and X-ray properties and compare the measured fields with equipartition field values. Finally, we use our results and recent results on a large sample of stars in Taurus to discuss the potential evolution of magnetic field properties between the age of Taurus (~2 Myr) and the age of TWA (~10 Myr). We find that the average stellar field strength increases with age; however, the total unsigned magnetic flux decreases as the stars contract onto the main sequence.
Electromagnetically induced transparency with Laguerre–Gaussian modes in ultracold rubidium

Abstract We demonstrate electromagnetically induced transparency with the control laser in a Laguerre–Gaussian mode. The transmission spectrum is studied in an ultracold gas for the D2 line in both 85Rb and 87Rb, where the decoherence due to diffusion of the atomic medium is negligible. We compare these results to a similar configuration, but with the control laser in the fundamental laser mode. We model the transmission of a probe laser under both configurations, and we find good agreement with the experiment. We conclude that the use of Laguerre–Gaussian modes in electromagnetically induced transparency results in narrower resonance linewidths as compared to uniform control laser intensity. The narrowing of the linewidth is caused by the spatial distribution of the Laguerre–Gaussian intensity profile.
Cimetidine inhibits catechol estrogen metabolism in women.

Chronic cimetidine use in men is associated with hyperestrogenic side effects such as gynecomastia, which may be linked to inhibition of estradiol 2-hydroxylation. As this property of the drug might be helpful in hypoestrogenic states such as osteoporosis, we investigated the effect of cimetidine on estradiol metabolism in premenopausal and postmenopausal women. Using an in vivo radiometric assay, we found that the extent of estradiol 2-hydroxylation in premenopausal women (n = 9) was decreased by a 1-month course of cimetidine, 800 mg twice daily (44.0% +/- 3.5% v 31.2% +/- 4.1%, P less than .001). Among premenopausal smokers (n = 3), the response to cimetidine was approximately the same as nonsmokers. Serum estradiol levels (follicular phase) in these women were unaltered by cimetidine after 1 month, while concentrations of sex hormone-binding globulin (SHBG) were decreased by 30% (P = .018). Postmenopausal women (n = 5) initially received a lower dose of cimetidine (600 mg twice daily) for 2 weeks, followed by a higher dose (1200 mg twice daily) for another 2 weeks. The extent of estradiol 2-hydroxylation was significantly reduced by the low dose (44.4% +/- 4.5% v 24.3% +/- 3.0%, P less than .005), with minimal further reduction after the high dose (21.7% +/- 1.6%). After 4 weeks of cimetidine treatment, serum estradiol levels increased significantly from 30.0 +/- 6.4 to 59.8 +/- 13.1 pg/mL (P = .033), while SHBG was unaffected. Cimetidine was found to have little effect on selected biochemical indices of bone and calcium metabolism in both groups of women.(ABSTRACT TRUNCATED AT 250 WORDS)
Piggy Bank: Experience the Semantic Web inside your web browser

The Semantic Web Initiative envisions a Web wherein information is offered free of presentation, allowing more effective exchange and mixing across web sites and across web pages. But without substantial Semantic Web content, few tools will be written to consume it; without many such tools, there is little appeal to publish Semantic Web content. To break this chicken-and-egg problem, thus enabling more flexible information access, we have created a web browser extension called Piggy Bank that lets users make use of Semantic Web content within Web content as users browse the Web. Wherever Semantic Web content is not available, Piggy Bank can invoke screenscrapers to re-structure information within web pages into Semantic Web format. Through the use of Semantic Web technologies, Piggy Bank provides direct, immediate benefits to users in their use of the existing Web. Thus, the existence of even just a few Semantic Web-enabled sites or a few scrapers already benefits users. Piggy Bank thereby offers an easy, incremental upgrade path to users without requiring a wholesale adoption of the Semantic Web's vision. To further improve this Semantic Web experience, we have created Semantic Bank, a web server application that lets Piggy Bank users share the Semantic Web information they have collected, enabling collaborative efforts to build sophisticated Semantic Web information repositories through simple, everyday's use of Piggy Bank.
ABS control using optimum search via sliding modes

The paper presents the control design for antilock braking systems via the sliding mode approach. In this study the authors formulate the problem as that of extremum searching in a highly uncertain situation. The authors consider the friction force as an output of the dynamic system which includes mechanical motion equations and the hydraulic circuit equations. This setting is complicated by the optimized function being a priori unknown, and the input (slip) not being measurable. >
Raman enhancement methods for molecular structure characterization of optical thin films

Abstract Raman scattering from thin dielectric films and multilayers carries information about the chemical and physical state of the film and its interfaces. Because of the low Raman scattering probability and the short optical paths in films and interfaces, several techniques to enhance Raman signals have been developed. Among these are interference enhancement in multilayer structures, path length extension by waveguide methods, coherent non-linear Raman spectroscopies and resonant Raman enhancement by the use of short wavelength excitation. We shall discuss here the advantages and limitations of interference and resonance enhancement methods. A common theme of both methods is the measurement of a Raman excitation profile spectrum by tuning the probe laser wavelength across an optical interference passband or across the electronic band gap of the film material. While interference is an optical effect which enhances the Raman spectrum uniformly, under resonance Raman conditions selective enhancement is observed for vibrational modes which are strongly coupled to the allowed electronic transitions in the dielectric material. The principal limitation of resonance Raman probes of solid films is the optical damage threshold which is easily exceeded by typical UV pulsed probe power levels near the electronic band edge. Examples and techniques to achieve resonance Raman excitation profiles in dielectric films will be discussed.
Relationship between vertical shear rate and kinetic energy dissipation rate in stably stratified flows

[1] High resolution direct numerical simulations of strongly stratified turbulence are analyzed in order to investigate the relationship between vertical shearing of horizontal motions and the dissipation rate of kinetic energy. The relative magnitude of each component of the dissipation rate is examined as a function of the Reynolds number and of the buoyancy Reynolds number. From the simulation results, in conjunction with published laboratory results, it is concluded that (1) the simulation results are consistent with the laboratory data but span a much larger range of buoyancy Reynolds number, (2) the ratio of the square of the vertical shear rate to the dissipation rate is a strong function of buoyancy Reynolds number, and (3) the approximation that vertical shear rate is the dominant cause of energy dissipation rate is only good when the buoyancy Reynolds number is less than order one.
Composing letters with a simulated listening typewriter

With a listening typewriter, what an author says would be automatically recognized and displayed in front of him or her. However, speech recognition is not yet advanced enough to provide people with a reliable listening typewriter. An aim of our experiments was to determine if an imperfect listening typewriter would be useful for composing letters. Participants dictated letters, either in isolated words or in consecutive word speech. They did this with simulations of listening typewriters that recognized either a limited vocabulary (1000 or 5000 words)or an unlimited vocabulary. Results suggest that some versions, even upon first using them, could be at least as good as traditional methods of handwriting and dictating. Isolated word speech with large vocabularies may provide the basis for a useful listening typewriter.
Nonequilibrium regime of airflows in contoured nozzles - Theory and experiments.

Experimental data are compared with theory for the expansion of high-temperat ure air through a 9.492-in. exit diameter, contoured nozzle. An exact numerical calculation of a one-dimensional equilibrium and nonequilibrium expansion based on the measured potential nozzle flow is included. Thermodynamic calculations are based on rotational, vibrational, and electronic partition functions with associated corrections for anharmonicity, rotational-vibrational coupling, and rotational stretching. Flow properties are calculated for an air model containing N£, C>2, NO, N, O, and argon. An experimental program utilizing a 3-Mw, d.c. arc heater provided design reservoir conditions of 114.7 atm and 4120°K to produce a Mach number 10.23 "near-equilibrium" flow. Fully instrumented nozzle exit surveys of mass flux, impact pressure, and steady-state calorimetry along with nozzle wall pressures were utilized to derive freestream velocity, density, and total enthalpy. A second case with reservoir conditions of 132.7 atm and 5725°K was found to be in good agreement with the nonequilibrium expansion process. A third case, reservoir conditions of 35.4 atm and 5361 °K, yielded a nonequilibrium , parallel flow resembling a gas nearly "frozen" directly after the nozzle throat.
Mass generation from tachyon condensation for vector fields on D-branes

The level truncation approach to string field theory is used to study the zero-momentum action for vector excitations on a bosonic D-brane which has been annihilated by tachyon condensation. It is shown that in the true vacuum the translation zero modes associated with transverse scalars on the D-brane are lifted by spontaneous generation of mass terms. Similarly, the U(1) gauge field on the brane develops a non-zero mass term.
Modeling blood-brain barrier partitioning using the electrotopological state.

The challenging problem of modeling blood-brain barrier partitioning is approached through topological representation of molecular structure. A QSAR model is developed for in vivo blood-brain partitioning data treated as the logarithm of the blood-brain concentration ratio. The model consists of three structure descriptors: the hydrogen E-State index for hydrogen bond donors, HST(HBd); the hydrogen E-State index for aromatic CHs, HST(arom); and the second order difference valence molecular connectivity index, d2χv (q2 = 0.62.) The model for the set of 106 compounds is validated through use of an external validation test set (20 compounds of the 106, MAE = 0.33, rms = 0.38), 5-fold cross-validation (MAE = 0.38, rms = 0.47), prediction of +/− values for an external test set (27/28 correct), and estimation of logBB values for a large data set of 20 039 drugs and drug-like compounds. Because no 3D structure information is used, computation of logBB by the model is very fast. The quality of the validation sta...
Forensic analysis of database tampering

Regulations and societal expectations have recently expressed the need to mediate access to valuable databases, even by insiders. One approach is tamper detection via cryptographic hashing. This article shows how to determine when the tampering occurred, what data was tampered with, and perhaps, ultimately, who did the tampering, via forensic analysis. We present four successively more sophisticated forensic analysis algorithms: the Monochromatic, RGBY, Tiled Bitmap, and a3D algorithms, and characterize their “forensic cost” under worst-case, best-case, and average-case assumptions on the distribution of corruption sites. A lower bound on forensic cost is derived, with RGBY and a3D being shown optimal for a large number of corruptions. We also provide validated cost formulae for these algorithms and recommendations for the circumstances in which each algorithm is indicated.
Orientation Waves in a Director Field with Rotational Inertia

We study a variational system of nonlinear hyperbolic partial differential equations that describes the propagation of orientation waves in a director field with rotational inertia and potential energy given by the Oseen-Frank energy from the continuum theory of nematic liquid crystals. There are two types of waves, which we call splay and twist waves, respectively. Weakly nonlinear splay waves are described by the quadratically nonlinear Hunter-Saxton equation. In this paper, we derive a new cubically nonlinear asymptotic equation that describes weakly nonlinear twist waves. This equation provides a surprising representation of the Hunter-Saxton equation, and like the Hunter-Saxton equation it is completely integrable. There are analogous cubically nonlinear representations of the Camassa-Holm and Degasperis-Procesi equations. Moreover, two different, but compatible, variational principles for the Hunter-Saxton equation arise from a single variational principle for the primitive director field equations in the two different limits for splay and twist waves. We also use the asymptotic equation to analyze a one-dimensional initial value problem for the director-field equations with twist-wave initial data.
Active suppression of aeroelastic instabilities on a forward-swept wing

Etude des possibilites d'utilisation de systemes de controle retroactif pour la prevention des instabilites aeroelastiques multiples apparaissant simultanement a proximite d'une aile fleche
Social Movements and Ecological Modernization: The Transformation of Pulp and Paper Manufacturing

Ecological modernization theory posits that social movements play a central role in the environmental transformation of contemporary society. How they do so has received limited scholarly attention. This article seeks to reduce this thesis to a number of propositions which are then examined in light of the experience of the pulp and paper industry in the 1980s and 1990s. Drawing on field research and interviews in Southeast Asia, Australia and the United States, as well as available data, the study finds that social movements were instrumental in the environmental transformation of the pulp industry, with important differences between North and South. It concludes with a call for more nuanced studies of the influence of social movements on different sectors and countries, especially in newly industrializing countries where more tenuous and dependent forms of ecological modernization may be emerging.
The management of partnering development in I/S outsourcing

The I/S literature reflects an increased interest in outsourcing and partnerships with vendor firms. This paper selects a model of partnership development from the management literature and applies it to I/S partnering. The emphasis is on the manageable aspects of partnership development and the actions that I/S managers can take to speed partnership development and deepen relationships with vendors. Two case studies of I/S partnership development are used to test and illustrate the concepts developed from the model of partnering behaviour.
A critical-exponent Balian–Low theorem

Using a variant of the Sobolev Embedding Theorem, we prove an uncertainty principle related to Gabor systems that generalizes the Balian--Low Theorem. Namely, if $f\in H^{p/2}(\R)$ and $\hat f\in H^{p'/2}(\R)$ with $1<p< \infty$, $\frac{1}{p}+\frac{1}{p'}=1$, then the Gabor system $\mathcal G(f,1,1)$ is not a frame for $L^2(\R)$. In the $p=1$ case, we obtain a generalization of the result in \cite{bcps}.
Smart computational fracture of materials and structures

Abstract The use of the finite element method for complex engineering problems is now common. To ease the burden on the engineer the development of smart or adaptive computational methods is now required to model complex problems. In this paper we investigate the development of an adaptive finite element method for fracture-related problems. The adaptive method involves various stages which include the finite element analysis, error estimation/indication, mesh refinement and fracture/failure analysis in a loop. Some simple error estimators, based on stress projection, are used to investigate the adaptive finite element process. Element refinement is based on three schemes; the first and second are a simple and hierarchical refinement scheme with transitioning which avoids the need for constraint equations between element boundaries. Another scheme based on constraint equations between elements is also examined. The energy norm is used to estimate the element error. The software has the ability to introduce a discrete fracture in the structure according to standard fracture analysis practice. Crack tip parameters are calculated using a least-squares fit of the displacements into the asymptotic crack tip displacement field. Some simple examples are used to investigate the adaptive process, its behavior and some of the practical problems encountered. The convergence and equilibrium of the adaptive process, in terms of global error in the energy norm, are investigated. In the example the same problem is analyzed using both a fine computational grid and a coarse one. The coarse mesh is then adapted using the three different procedures available. The estimated error in the solution and the stress intensity are shown against the number of elements and number of iterations. Some further areas of research in adaptive finite element analysis are discussed.
Full-Scale Turbofan-Engine Turbine-Transfer Function Determination Using Three Internal Sensors

Existing NASA/Honeywell EVNERT full-scale static engine test data is analyzed by using source-separation techniques in order to determine the turbine transfer of the currently sub-dominant combustor noise. The results are used to assess the combustor-noise prediction capability of the Aircraft Noise Prediction Program (ANOPP). Time-series data from three sensors internal to the Honeywell TECH977 research engine is used in the analysis. The true combustor-noise turbine-transfer function is educed by utilizing a new three-signal approach. The resulting narrowband gain factors are compared with the corresponding constant values obtained from two empirical acoustic-turbine-loss formulas. It is found that a simplified Pratt & Whitney formula agrees better with the experimental results for frequencies of practical importance. The 130 deg downstream-direction far-field 1/3-octave sound-pressure levels (SPL) results of Hultgren & Miles are reexamined using a post-correction of their ANOPP predictions for both the total noise signature and the combustion-noise component. It is found that replacing the standard ANOPP turbine-attenuation function for combustion noise with the simplified Pratt & Whitney formula clearly improves the predictions. It is recommended that the GECOR combustion-noise module in ANOPP be updated to allow for a user-selectable switch between the current transmission-loss model and the simplified Pratt & Whitney formula. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The Subsonic Fixed Wing Project's Reduce-Perceived-Noise Technical Challenge aims to develop concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. The reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic.
Positive semigroups and abstract Lyapunov equations

We consider abstract equations of the form $$\mathcal {A}x=-z$$ on a locally convex space, where $$\mathcal {A}$$ generates a positive semigroup and $$z$$ is a positive element. This is an abstract version of the operator Lyapunov equation $$A^*P+PA=-Q$$ from control theory. It is proved that under suitable assumptions existence of a positive solution implies that $$-\mathcal {A}$$ has a positive inverse, and the generated semigroup is asymptotically stable. We do not require that $$z$$ is an order unit, or that the space contains any order units. As an application, we generalize Wonham’s theorem on the operator Lyapunov equations with detectable right hand sides to reflexive Banach spaces.
The Role of Palliative Care in Medical Education

Palliative care has a limited presence in medical education. This commentary discusses palliative care and argues that it teaches good medical practice and the art of medicine and should be an esse...
The Scope and Generality of Bell's Theorem

I present what might seem to be a local, deterministic model of the EPR-Bohm experiment, inspired by recent work by Joy Christian, that appears at first blush to be in tension with Bell-type theorems. I argue that the model ultimately fails to do what a hidden variable theory needs to do, but that it is interesting nonetheless because the way it fails helps clarify the scope and generality of Bell-type theorems. I formulate and prove a minor proposition that makes explicit how Bell-type theorems rule out models of the sort I describe here.
Overview of the military computer family architecture selection

This paper presents an overview of the selection process employed to choose a single Computer Family Architecture (CFA) to be used in a new Military Computer Family (MCF) intended for use in Army and Navy Systems. A joint Army/Navy Selection Committee studied the suitability of a number of architectures, and intensively evaluated three "final candidate" architectures, before selecting one, the PDP-11, for use with the MCF.
A path integral approach to noncommutative superspace

A path integral formula for the associative star-product of two superfields is proposed. It is a generalization of the Kontsevich-Cattaneo-Felder's formula for the star-product of functions of bosonic coordinates. The associativity of the star-product imposes certain conditions on the background of our sigma model. For generic background the action is not supersymmetric. The supersymmetry invariance of the action constrains the background and leads to a simple formula for the star-product.
On the cohomology of central Frattini extensions

Abstract In this paper we provide calculations for the mod p cohomology of certain p-groups, using topological methods. More precisely, we look at p-groups G defined as central extensions 1→V→G→W→1 of elementary abelian groups such that G/[G,G]⊗ F p =W and the defining k-invariants span the entire image of the Bockstein. We show that if p>dim V−dim W+1 , then the mod p cohomology of G can be explicitly computed as an algebra of the form P ⊗A where P is a polynomial ring on two-dimensional generators and A is the cohomology of a compact manifold which in turn can be computed as the homology of a Koszul complex. As an application we provide a complete determination of the mod p cohomology of the universal central extension 1→H 2 (W, F p )→U→W→1 provided p>( n 2 )+1 , where n=dim W .
Dynamic learning of pairwise and three-way entanglement

In previous work, we have developed a dynamic learning paradigm for “programming” a general quantum computer. A learning algorithm is used to find a set of parameters for a coupled qubit system such that the system at an initial time evolves at the final time to a state in which a given measurement results in the desired calculation value. This can be thought of as a quantum neural network (QNN). Here, we apply our method to a system of three qubits, and demonstrate training the quantum computer to estimate both pairwise and three-way entanglement of the initial state.
A Pulsed Power Supply for Injection Bump Magnets

A controlled resonant circuit charges an energy-storage capacitor bank with a precision of ±0.1 percent from an unregulated ± 2-percent dc source. The capacitor bank energizes an efficient thyristor-controlled pulse-forming discharge circuit. These circuits, which generate magnet pulses of 300 J at a rate of 30/s, are analyzed in this paper.
The reinforcing effects of ethanol within the nucleus accumbens shell involve activation of local GABA and serotonin receptors

Ethanol is reinforcing within the nucleus accumbens shell (NACsh), but the underlying mechanisms remain unclear. Ethanol can potentiate the function of the GABAA, GABAB, and serotonin-3 (5-HT3) receptors. Therefore, the current study tested the hypothesis that activation of these receptors would be involved in the reinforcing effects of ethanol in the NACsh. An intracranial self-administration (ICSA) procedure was used to assess the reinforcing effects of ethanol in the NACsh of alcohol preferring (P) rats. The ICSA consisted of seven sessions: four sessions to establish 150 mg% ethanol self-infusion into the NACsh; sessions 5 and 6 with co-infusion of ethanol plus one concentration of the GABAA antagonist bicuculline (10 or 100 µM), the GABAB antagonist SCH 50911 (50, 75 or 100 µM), or the 5-HT3 receptor antagonist zacopride (10 or 100 µM); and session 7 with 150 mg% ethanol alone. All groups self-infused ethanol into the NACsh and readily discriminated the active from inactive lever during the acquisiti...
Volumetric T-spline construction using Boolean operations

In this paper, we present a novel algorithm for constructing a volumetric T-spline from B-reps inspired by constructive solid geometry Boolean operations. By solving a harmonic field with proper boundary conditions, the input surface is automatically decomposed into regions that are classified into two groups represented, topologically, by either a cube or a torus. We perform two Boolean operations (union and difference) with the primitives and convert them into polycubes through parametric mapping. With these polycubes, octree subdivision is carried out to obtain a volumetric T-mesh, and sharp features detected from the input model are also preserved. An optimization is then performed to improve the quality of the volumetric T-spline. The obtained T-spline surface is C 2 everywhere except the local region surrounding irregular nodes, where the surface continuity is elevated from C 0 to G 1. Finally, we extract trivariate Bezier elements from the volumetric T-spline and use them directly in isogeometric analysis.
Dirhodium(II)-catalyzed carbonyl ylide generation. Stereoelectronic control in dioxolane formation

The combination of ethyl diazoacetate with aryl aldehydes in the presence of copper(I) or rhodium(II) catalysts results in the formation of 1,3-dioxolane products in moderate to good yields. These reactions occur through a pathway that involves ylide intermediates. Catalyst-dependent diastereocontrol is observed and suggests that metal-associated ylides are involved in the product-determining step. The influence of aryl aldehyde substituents has been determined.
Non-lte spectra of accretion disks around intermediate-mass black holes

We have calculated the structures and the emergent spectra of stationary, geometrically thin accretion disks around 100 and 1000 M☉ black holes in both the Schwarzschild and extreme Kerr metrics. Equations of radiative transfer, hydrostatic equilibrium, energy balance, ionization equilibrium, and statistical equilibrium are solved simultaneously and consistently. The six most astrophysically abundant elements (H, He, C, N, O, and Fe) are included, as well as energy transfer by Comptonization. The observed spectrum as a function of viewing angle is computed, incorporating all general relativistic effects. We find that, in contrast with the predictions of the commonly used multicolor disk (MCD) model, opacity associated with photoionization of heavy elements can significantly alter the spectrum near its peak. These ionization edges can create spectral breaks visible in the spectra of slowly spinning black holes viewed from almost all angles and in the spectra of rapidly spinning black holes seen approximately pole-on. For fixed mass and accretion rate relative to Eddington, both the black hole spin and the viewing angle can significantly shift the observed peak energy of the spectrum, particularly for rapid spin viewed obliquely or edge-on. We present a detailed test of the approximations made in various forms of the MCD model. Linear limb-darkening is confirmed to be a reasonable approximation for the integrated flux but not for many specific frequencies of interest.
Proportionate progress: A notion of fairness in resource allocation

Given a set ofn tasks andm resources, where each taskx has a rational weightx.w=x.e/x.p,0<x.w<1, aperiodic schedule is one that allocates a resource to a taskx for exactlyx.e time units in each interval [x.p·k, x.p·(k+1)) for allk∈N. We define a notion of proportionate progress, called P-fairness, and use it to design an efficient algorithm which solves the periodic scheduling problem.
Neighboring gray level dependence matrix for texture classification

Abstract A new approach, neighboring gray level dependence matrix (NGLDM), for texture classification is presented. The major properties of this approach are as follows: (a) texture features can be easily computed; (b) they are essentially invariant under spatial rotation; (c) they are invariant under linear gray level transformation and can be made insensitive to monotonic gray level transformation. These properties have enhanced the practical applications of the texture features. The accuracies of the classification are comparable with those found in the literature.
Experimental Study of the Flow Field Inside a Whirling Annular Seal

The flow field inside a whirling annular seal has been measured using a 3-D Laser Doppler Anemometer (LDA) system. The seal investigated has a clearance of 1.27 mm, a length of 37.3 mm and is mounted on a drive shaft with a 50 percent eccentricity ratio. This results in the rotor whirling at the same speed as the shaft rotation (whirl ratio = 1.0). The seal is operated at a Reynolds number of 12000 and a Taylor number of 6300 (3600 rpm). The 3-D LDA system is equipped with a rotary encoding system which is used to produce phase averaged measurements of the entire mean velocity vector field and Reynolds stress tensor field from 0.13 mm upstream to 0.13 mm downstream of the seal. The mean velocity field reveals a highly three-dimensional flow field with large radial velocities near the inlet of the seal as well as a recirculation zone on the rotor surface. The location of maximum mean axial velocity migrates from the pressure side of the rotor at the inlet to the suction side at the exit. Turbulence production is a maximum near the seal inlet as indicated by the rapid increase of the turbulence kinetic energy (kappa). However, turbulence production and dissipation attain equilibrium fairly quickly with kappa remaining relatively constant over the last half of the seal.
Discussion of “The Internet downturn: Finding valuation factors in Spring 2000”

This article reviews ‘The Internet downturn: Finding valuation factors in Spring 2000’ by Keating, Lys, and Magee (KLM). Their paper contributes to a growing literature on the valuation of Internet firms, finding strong relations among market prices, accounting variables, and assorted ‘neweconomy’ measures of performance. I argue that their results tell us more about investors’ (mis-)perceptions in Spring 2000 than about the underlying economics of Internet firms. Moreover, the valuations seem unlikely to repeat. KLM’s findings may not generalize to other firms or time periods. r 2002 Elsevier Science B.V. All rights reserved.
Convenient Access to Bicyclic and Tricyclic Diazenes

Heating the tosylhydrazone of an omega-alkenyl ketone or aldehyde to reflux in toluene in the presence of K(2)CO(3) delivered the bicyclic diazene. Irradiation of the diazene converted it to the cyclopropane. This appears to be a generally useful method for the construction of substituted cyclopentanes and cyclohexanes.
Spinel ferrite/MnO core/shell nanoparticles : Chemical synthesis of all-oxide exchange biased architectures

In this communication, we report the synthesis and characterization of organic-capped core/shell CoFe2O4/MnO nanoparticles. Magnetic properties of the core/shell nanoparticles were compared to those of individual CoFe2O4 and MnO nanoparticles prepared with similar methods. Magnetic measurements revealed that the core/shell nanoparticles displayed a shift in the hysteresis loops corresponding to exchange biasing exchange fields of about 0.6 kOe, due to the ferrimagnetic/antiferromagnetic interface.
Isothermal Fatigue Behavior and Damage Modeling of a High Temperature Woven PMC

This study focuses on the fully reversed fatigue behavior exhibited by a carbon fiber/polyimide resin woven laminate at room and elevated temperatures. Nondestructive video edge view microscopy and destructive sectioning techniques were used to study the microscopic damage mechanisms that evolved. The elastic stiffness was monitored and recorded throughout the fatigue life of the coupon. In addition, residual compressive strength tests were conducted on fatigue coupons with various degrees of damage as quantified by stiffness reduction. Experimental results indicated that the monotonic tensile properties were only minimally influenced by temperature, while the monotonic compressive and fully reversed fatigue properties displayed greater reductions due to the elevated temperature. The stiffness degradation as a function of cycles, consisted of three stages; a short-lived high degradation period, a constant degradation rate segment covering the majority of the life, and a final stage demonstrating an increasing rate of degradation up to failure. Concerning the residual compressive strength tests at room and elevated temperatures, the elevated temperature coupons appeared much more sensitive to damage. At elevated temperatures, coupons experienced a much larger loss in compressive strength when compared to room temperature coupons with equivalent damage. The fatigue damage accumulation law proposed for the model incorporatesmore » a scalar representation for damage, but admits a multiaxial, anisotropic evolutionary law. The model predicts the current damage (as quantified by residual stiffness) and remnant life of a composite that has undergone a known load at temperature. The damage/life model is dependent on the applied multiaxial stress state as well as temperature. Comparisons between the model and data showed good predictive capabilities concerning stiffness degradation and cycles to failure.« less