bluuebunny/crossref_metadata_2025 huggingface dataset:
Photodissociation spectroscopy of stored CH+ ions: Detection, assignment, and close-coupled modeling of near-threshold Feshbach resonances
Authors: Hechtfischer Ulrich , Williams Carl J. , Lange Michael , Linkemann Joachim , Schwalm Dirk , Wester Roland , Wolf Andreas , Zajfman Daniel
Published: October 2002

We have measured and theoretically analyzed a photodissociation spectrum of the CH+ molecular ion in which most observed energy levels lie within the fine-structure splitting of the C+ fragment and predissociate, and where the observed irregular line shapes and dipole-forbidden transitions indicate that nonadiabatic interactions lead to multichannel dynamics. The molecules were prepared in low rotational levels J″=0–9 of the vibrational ground state X 1Σ+ (v″=0) by storing a CH+ beam at 7.1 MeV in the heavy-ion storage ring TSR for up to 30 s, which was sufficient for the ions to rovibrationally thermalize to room temperature by spontaneous infrared emission. The internally cold molecules were irradiated with a dye laser at photon energies between 31 600–33 400 cm−1, and the resulting C+ fragments were counted with a particle detector. The photodissociation cross section displays the numerous Feshbach resonances between the two C+ fine-structure states predicted by theory for low rotation. The data are analyzed in two steps. First, from the overall structure of the spectrum, by identifying branches, and by a Le Roy–Bernstein analysis of level spacings we determine the dissociation energy D0=(32 946.7±1.1) cm−1 (with respect to the lower fine-structure limit) and assign the strongest features to the vibrational levels v′=11–14 of the dipole-allowed A 1Π state. The majority of the 66 observed resonances cannot be assigned in this way. Therefore, in a second step, the complete spectrum is simulated with a close-coupling model, starting from recent ab initio Born–Oppenheimer potentials. For the long-range induction, dispersion and exchange energies, we propose an analytical expression and derive the C6 coefficients. After a systematic variation of just the vibrational defects of the four Born–Oppenheimer potentials involved, the close-coupling model yields a quantitative fit to the measured cross section in all detail, and is used to assign most of the remaining features to the dipole-forbidden a 3Π state (v′=17–20), and some to the weakly bound c 3Σ+ state (v′=0–2). The model potentials, which reproduce the spectrum and compactly represent the spectroscopic data, should help to predict more accurately C++H scattering in the interstellar medium.
Theoretical rate constants for the OH+CO→H+CO2 reaction using variational transition state theory on analytical potential energy surfaces
Authors: Valero Rosendo , Kroes Geert-Jan
Published: October 2002

Variational transition state theory, within the canonical unified statistical model including multidimensional tunneling corrections, has been applied to derive thermal rate constants in the temperature range 80–2800 K for the title reaction and its deuterated counterpart in the low- and high-pressure limits. The analytical potential energy surfaces of Bradley and Schatz (BS) and of Yu, Muckerman, and Sears have been employed. In the low-pressure limit, the results are comparable though slightly better for the BS potential surface at the lowest temperatures. In the high-pressure limit, the BS potential surface is notably closer to the experimental data, which are only available at temperatures close to and higher than 300 K. The kinetic isotope effect (KIE) at room temperature is better predicted by the BS surface, although both surfaces fail to reproduce the experimental dependence of the KIE on temperature.
Spectroscopy of the low-lying states of the group III–V diatomics, AlP, GaP, InP, and GaAs via anion photodetachment spectroscopy
Authors: Gómez Harry , Taylor Travis R. , Zhao Yuexing , Neumark Daniel M.
Published: October 2002

The low-lying electronic states of AlP, GaP, InP, and GaAs have been probed using anion photoelectron spectroscopy and zero electronic kinetic energy spectroscopy. We observe transitions from the anion Σ+2 and low-lying Π2 states to the triplet (3Σ− and Π3 states) and singlet (1Π, Σ+1, and Δ1 states) manifolds of the neutral species. The spectra of the triplet manifolds are particularly complex, with overlapping spin–orbit and vibrational progressions. Spin–orbit splittings, term energies, and vibrational frequencies are reported and compared to previous electronic structure calculations on the anions and neutrals, as well as to those parameters determined previously for the isovalent homonuclear diatomics Si2, Ge2, and Sn2.
Photodissociation and ab initio studies of Mg+(NH3)n, n=1–4: Electronic structure and photoinduced reaction
Authors: Yoshida Shinji , Daigoku Kota , Okai Nobuhiro , Takahata Akihiro , Sabu Akiyoshi , Hashimoto Kenro , Fuke Kiyokazu
Published: October 2002

Photodissociation spectra of Mg+(NH3)n (n=1–4) cluster ions are examined in the wavelength region of 240–1200 nm. From the comparison with the results of ab initio calculations for the structure and the excitation energies of these clusters, the observed absorption bands are assigned to the transitions derived from the P2–2S transition of Mg+ ion. The extensive redshift of the observed spectra is ascribed to the formation of a one-center ion-pair state. In the photolysis of Mg+NH3, NH3+ and Mg+NH2 ions are produced via photoinduced charge transfer and intracluster reaction processes, respectively, in addition to the Mg+ ion generated by the evaporation of ammonia molecules. For n=2, both the intracluster reaction and evaporation are dominant decay processes, while the evaporation is the sole photodissociation channel for larger clusters. The branching fractions of these processes are found to depend strongly on the solvation number n and also on the photolysis wavelength. The energetics and the dynamics of the dissociation processes are discussed in relation to the redox reaction of metal ions.
The role of sidechain packing and native contact interactions in folding: Discontinuous molecular dynamics folding simulations of an all-atom Gō model of fragment B of Staphylococcal protein A
Authors: Linhananta Apichart , Zhou Yaoqi
Published: October 2002

Protein topology, which refers to the arrangement of secondary structures of proteins, has been extensively investigated to examine its role in protein folding. However, recent studies show that topology alone cannot account for the variation of folding behaviors observed in some proteins of the same structural family. In a recent work, we showed that the native structure of the second β hairpin of protein G predicts a folding mechanism that is different from topology-based models. Here, we continue to examine how much one can learn about folding mechanism from native structure. This work focuses on fragment B of Staphylococcal protein A (BpA) – a three-helix (H1, H2, and H3) bundle protein. Using a recently developed all-atom (except nonpolar hydrogen) Gō model interacting with simple discontinuous potentials, the folding of the model BpA was observed in 112 out of 249 trajectories within 50 h of CPU times on a Pentium PC (1 GHz). The model successfully captured several specific properties of BpA that have been observed experimentally. These include the higher stability of H3 compared to H1 and H2, and the higher stability of the H2–H3 microdomain compared to the H1–H2 microdomain. These specific details were not produced by a topology-based square-well model of BpA. Thus, the result further supports the important role of sidechain packing in determining the specific pathway of protein folding. Additional 96 000 short simulations were performed to locate the transition states of the two folding pathways. The limitation of the Gō model and its possible improvement are also discussed.
Phase diagram of dilute polyelectrolytes: Collapse and redissolution by association of counterions and co-ions
Authors: Solis Francisco J.
Published: October 2002

Dilute solutions of strongly charged polymer electrolytes undergo, upon addition of multivaltent salt to the solutions, a phase transition from extended to collapsed or bundled conformations. Upon further addition of salt they experience a second transition, a redissolution back into extended conformations. This paper presents a theoretical study of the structure and properties of the phase diagram of these solutions. On the basis of phenomenological observations a schematic phase diagram is constructed that allows a simple and explicit determination of the direction of the tie lines within the coexistence region. The actual shape of the coexistence boundary is determined by means of a model mean free energy functional that explicitly includes the possibility of association of both counterions and co-ions to the electrolytes. It is found that it is possible to redissolve the electrolytes into conformations where the bare charge of the electrolytes is overcompensated by the counterions but, due to the associated co-ions, can have either sign of total effective charge. When co-ion association is possible, the redissolution approximately coincides with the reassociation of the co-ions and counterions in the bulk of the solution.
Diffusion-controlled reactions in an inhomogeneous medium: Intermediate and high concentration of reagents
Authors: Buján-Nuñez M. C. , López-Quintela M. A.
Published: October 2002

In computer simulations of reactions in a disordered no homogeneous medium consisting of a solvent containing randomly located stationary spherical obstacles, reagent first encounter rate ν depended on the volume fraction of reagents φ in accordance with the law ν=KφRβ, where the prefactor K and the scaling factor β both depend on both the volume fraction of obstacles, φ, and the size of the obstacles relative to the reagents. Below a critical obstacle concentration φc, both K and β increase with φ; above φc, both fall with increasing φ. The value of φc is roughly the value at which there is a 99% probability that clusters of closely spaced obstacles stretch from side to side of the simulation cell. The increase in K at lower obstacle concentrations, which is largely attributable to increasing effective reagent concentration, results in enhancement of the reagent first encounter rate at moderate to high bulk reagent concentrations (whereas at low reagent concentrations this effect is outweighed by the simultaneous increase in β). Enhancement is most marked for larger obstacles, which cause less compartmentalization of the medium for a given increase in effective reagent concentration.
Ground state splitting of vertically stacked indium arsenide self-assembled quantum dots
Authors: Li Shuwei , Koike Kazuto
Published: October 2002

An attractive feature of vertically stacked InAs/AlGaAs quantum dots (QDs), which were buried in AlGaAs high potential barrier and spacer epilayer and grown by molecular-beam epitaxy with size-controlled growth, exhibits an unknown macroscopic quantum phenomenon (i.e., phase-change splitting of the ground state). In the vertically aligned QDs, due to many-body effect and quantum-mechanical renormalization, the electron ground state splits into a series of peaks of which the intensity gradually, systematically decreases to redshift direction with a wavelength constant. By the way, energy levels of electrons and holes might really be “seen” by deep level transient spectroscopy to which the photoluminescence experiment is in an excellent agreement.
Deconvolving long-pulse electron-beam centroid data from resistive wall-current monitors
Authors: Carlsten Bruce E.
Published: October 2002

A technique is described to deconvolve long-pulse electron-beam centroid data from resistive wall-current monitors. These monitors are typically capable of accurately measuring total current for tens of microseconds, but, due to magnetic diffusion, tend to give direct centroid measurements only up to hundreds of nanoseconds. As a result, resistive wall-current monitors are usually not considered reliable for long-pulse operation. However, the voltage signals azimuthally around the monitor still contains that information, and the information can be easily deconvolved by differentiating the signals. In this article, the diffusive part of Maxwell's equations is used to find an expression for the time response of a resistive wall-current monitor for a beam of arbitrary current and centroid evolution. A simple way of inverting this response is shown to find the beam centroid as a function of time within the electron pulse.
The superconducting gap of in situ MgB2 thin films by microwave surface impedance measurements
Authors: Hakim N. , Kusko C. , Sridhar S. , Soukiassian A. , Zeng X. H. , Xi X. X.
Published: October 2002

Precision measurements of the microwave surface resistance Rs of in situ MgB2 films directly reveal an exponential behavior of Rs at low temperature indicating a fully-gapped order parameter. The entire temperature dependence of Rs is well described by a Mattis–Bardeen formalism, but with a small gap ratio of Δ(0)/kTc=0.72, corresponding to Δ(0)=1.9 meV.
Strong exciton–photon coupling in a low-Q all-metal mirror microcavity
Authors: Hobson P. A. , Barnes W. L. , Lidzey D. G. , Gehring G. A. , Whittaker D. M. , Skolnick M. S. , Walker S.
Published: October 2002

We report the experimental observation of strong exciton–photon coupling in a planar microcavity composed of an organic semiconductor positioned between two metallic (silver) mirrors. Via transmission and reflectivity measurements, we observe a very large, room temperature Rabi splitting in excess of 300 meV. We show that the Rabi-splitting is enhanced in all-metal microcavities by a factor of more than 2 compared to an organic film positioned between a silver mirror and a dielectric mirror. This enhancement results from the significantly larger optical fields that are confined within all-metal microcavities.
AlGaN single-quantum-well light-emitting diodes with emission at 285 nm
Authors: Adivarahan V. , Wu S. , Chitnis A. , Pachipulusu R. , Mandavilli V. , Shatalov M. , Zhang J. P. , Khan M. Asif , Tamulaitis G. , Sereika A , Yilmaz I. , Shur M. S. , Gaska R.
Published: October 2002

We report on AlGaN single-quantum-well light-emitting diodes (LEDs) on sapphire with peak emission at 285 nm. A study is presented to identify the key material parameters controlling the device quantum efficiency. At room temperature, for a 200 μm×200 μm square geometry mesa type device, we obtain a power as high as 0.25 mW for 650 mA pulsed pumping. The LEDs show significantly higher output powers at temperatures below 100 K.
Direct-UV-written buried channel waveguide lasers in direct-bonded intersubstrate ion-exchanged neodymium-doped germano-borosilicate glass
Authors: Gawith Corin B. E. , Fu Alexander , Bhutta Tajamal , Hua Ping , Shepherd David P. , Taylor Elizabeth R. , Smith Peter G. R. , Milanese Daniel , Ferraris Monica
Published: October 2002

We report a technique for producing single-mode buried channel waveguide lasers in neodymium-doped SiO2:GeO2:B2O3:Na2O (SGBN) glass. Direct bonding forms the basis of this process, providing a buried waveguide layer in the photosensitive SGBN material into which channel confinement can be directly written with a focused UV beam. Characterization of a 7.5-mm-long device was performed using a Ti:Sapphire laser operating at 808 nm and the resultant 1059 nm channel waveguide laser output exhibited single-mode operation, milliwatt-order lasing thresholds, and propagation losses of <0.3 dB cm−1.
Near-field two-photon nanolithography using an apertureless optical probe
Authors: Yin Xiaobo , Fang Nicholas , Zhang Xiang , Martini Ignacio B. , Schwartz Benjamin J.
Published: October 2002

Near-field two-photon optical lithography is demonstrated by using ∼120 fs laser pulses at 790 nm in an apertureless near-field optical microscope, which produces lithographic features with ∼70 nm resolution. The technique takes advantage of the field enhancement at the extremity of a metallic probe to induce nanoscale two-photon absorption and polymerization in a commercial photoresist, SU-8. Even without optimization of the resist or laser pulses, the spatial resolution of this technique is as high as λ/10, nearly a factor of 2 better than techniques based on far field two-photon lithography.
Electron transport through strongly coupled AlInP/GaInP superlattices
Authors: Martı́nez R. E. , Appelbaum I. , Reddy C. V. , Sheth R. , Russell K. J. , Narayanamurti V. , Ryou J.-H. , Chowdhury U. , Dupuis R. D.
Published: October 2002

Using ballistic-electron-emission spectroscopy, electron transport through the principal (Γc,Lc) miniband of an (Al0.5In0.5P)11/(Ga0.5In0.5P)10 superlattice in the strong-coupling regime has been observed. Second derivative spectra of experimental data and Monte Carlo simulations were in agreement.
All-optical excitation and detection of microelectrical-mechanical systems
Authors: Graebner J. E. , Pau S. , Gammel P. L.
Published: October 2002

The radiation pressure of a chopped, 3 mW optical beam is used to excite angular motion of a Microelectrical-mechanical-systems’ (MEMS) mirror at its resonant frequencies. The modes are identified with a scanning interferometer, providing an all-optical excitation/detection scheme. The resonant frequencies, mode distributions, spring constants, and coupling between adjacent MEMS devices can, therefore, be studied without the use of electrostatic or other types of actuation. Within the experimental error of ∼30%, the amplitude of angular oscillation is equal to the theoretical value expected for radiation pressure.
Observation of domain texture in poled Pb(Mg1/3Nb2/3)O3–PbTiO3 crystals
Authors: Li J. F. , Ruette B. , Viehland D.
Published: October 2002

Mapping of domain distributions under constant Bragg conditions has been performed on poled (0.7)Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 crystals. Studies were done on crystals of cubic geometry, where each cube face was oriented along a 〈001〉c. Multiple domains with monoclinic limiting symmetry (angle ∼173°–176°) were observed on all three (001)c faces. Perpendicular to the poling direction, domain modulations were observed by a splitting of each variant.
Size control and charge storage mechanism of germanium nanocrystals in a metal-insulator-semiconductor structure
Authors: Teo L. W. , Choi W. K. , Chim W. K. , Ho V. , Moey C. M. , Tay M. S. , Heng C. L. , Lei Y. , Antoniadis D. A. , Fitzgerald E. A.
Published: October 2002

The size of germanium (Ge) nanocrystals in a trilayer metal-insulator-semiconductor memory device was controlled by varying the thickness of the middle (co-sputtered Ge+SiO2) layer. From analyses using transmission electron microscopy and capacitance–voltage measurements, we deduced that both electrons and holes are most likely stored within the nanocrystals in the middle layer of the trilayer structure rather than at the interfaces of the nanocrystals with the oxide matrix.
Transient photoinduced diffractive solid immersion lens for infrared microscopy
Authors: Cohn K. , Simanovskii D. , Smith T. , Palanker D.
Published: October 2002

We present a scanning near-field infrared microscopy technique using transient solid immersion lenses as near-field probes. The transient SILs were formed by photoinducing a zone plate structure on the surfaces of semiconductor wafers with high indices of refraction. Lenses with different number of zones have been tested using gallium phosphide and silicon wafers and their focusing properties were determined. We demonstrate that transient SILs can have lifetimes longer than 50 ps and provide the same high numerical apertures as conventional SILs. The use of transient SILs eliminates the need for mechanical scanning of the lens or sample, thus providing much faster scanning and the possibility to work with soft and liquid objects.
Magnetothermopower and magnon-assisted transport in ferromagnetic tunnel junctions
Authors: McCann Edward , Fal’ko Vladimir I.
Published: October 2002

We present a model of the thermopower in a mesoscopic tunnel junction between two ferromagnetic metals based upon magnon-assisted tunneling processes. In our model, the thermopower is generated in the course of thermal equilibration between two baths of magnons, mediated by electrons. We predict a particularly large thermopower effect in the case of a junction between two half-metallic ferromagnets with antiparallel polarizations, SAP∼−(kB/e), in contrast to SP≈0 for a parallel configuration.
Surface reactivity of highly vibrationally excited molecules prepared by pulsed laser excitation: CH4 (2ν3) on Ni(100)
Authors: Schmid Mathieu P. , Maroni Plinio , Beck Rainer D. , Rizzo Thomas R.
Published: October 2002

We report state resolved sticking coefficients for highly vibrationally excited CH4 on Ni(100) at well-defined kinetic energies in the range of 12–72 kJ/mol. Incident methane molecules are prepared by pulsed laser radiation in single rovibrational levels of the first overtone of the antisymmetric stretch (2ν3) at 6004.69 cm−1 and collided at normal incidence with a clean Ni(100) single crystal. We find that the vibrational excitation enhances the reaction probability by a factor 100 at an incident translational energy of 72 kJ/mol, but this enhancement increases to more than 4 orders of magnitude at low kinetic energy. Despite this large increase in the sticking coefficient, vibrational energy in 2ν3 appears to be about 80% as effective as an equivalent amount of translational energy in promoting the chemisorption reaction.
Control of crystallographic tilt in GaN grown on Si (111) by cantilever epitaxy
Authors: Katona T. M. , Speck J. S. , DenBaars S. P.
Published: October 2002

We have eliminated the crystallographic tilt associated with lateral growth during cantilever epitaxy by adjusting the lateral to vertical growth rate during the initial stages of growth. Cantilever epitaxy is a single growth run technique utilizing periodic, parallel mesas formed by etching the substrate. We have studied the relationship between the geometry of the “wing” region, the GaN spanning the etched trench, and the magnitude of crystallographic wing tilt. Cross-sectional scanning electron microscopy was used to characterize the geometry of the wing region, and x-ray diffraction was used to measure the magnitude of crystallographic tilt. It was found that by starting the GaN overgrowth with a slow lateral growth rate, compared to the vertical growth rate, a low tilt (⩽0.2°) was established and stabilized. The lateral growth rate can be increased during later stages of growth to assist in fast coalescence of neighboring stripes without significantly affecting the magnitude of crystallographic tilt.
Preferential carbon etching by hydrogen inside hexagonal voids of 6H-SiC(0001)
Authors: Sander Dirk , Wulfhekel Wulf , Hanbücken Margrit , Nitsche Serge , Palmari Jean Pierre , Dulot Frédéric , Arnaud d’Avitaya François , Leycuras André
Published: October 2002

6H-SiC(0001) samples have been etched in a hot-wall chemical vapor deposition reactor at a hydrogen pressure of 13 mbar at 1800 °C. The surface morphology and elemental composition have been studied by scanning electron microscopy and micro-Auger analysis. Stoichiometric etching of SiC with equal atomic concentrations of Si and C is found on the flat sections of the surface, but in hexagonal voids of the SiC samples, a selective removal of C, leading to a pure Si surface at the bottom of the voids, is observed. Fast gas diffusion is the main transport mechanism for etching of the flat surface, while Knudsen diffusion becomes important inside the voids. It is proposed that the lower diffusion constant of reaction products containing Si compared to those containing C, leads to a preferential removal of C and a Si enrichment inside the voids.
Thermal stability of atomic-layer-deposited HfO2 thin films on the SiNx-passivated Si substrate
Authors: Cho Moonju , Park Jaehoo , Park Hong Bae , Hwang Cheol Seong , Jeong Jaehack , Hyun Kwang Soo , Kim Young-Wug , Oh Chang-Bong , Kang Hee-Sung
Published: October 2002

HfO 2 thin films were deposited on SiNx-passivated Si wafers at 300 and 400 °C using an atomic-layer-deposition technique. The SiNx films were deposited by another atomic-layer-deposition process at 595 °C. The SiNx films worked well as barriers to both Si and O diffusion, resulting in a small decrease in the capacitance density even after post-annealing at temperatures up to 1000 °C, compared either to the HfO2 film deposited directly on Si or an Al2O3-barrier-layer/Si substrate. The decrease in the capacitance density after post-annealing, although relatively small, was due to Hf and O diffusion into the interface layer. Interestingly, post-annealing under an atmosphere containing small amount of oxygen (∼1%) decreased the capacitance density to a smaller degree. However, the interface and bulk capturing of the carrier was serious, resulting in a rather large hysteresis (∼100 mV) voltage in the capacitance–voltage measurements even after post-annealing.
HfO
2
/
SiO
2
interface chemistry studied by synchrotron radiation x-ray photoelectron spectroscopy
Authors: Renault O. , Samour D. , Damlencourt J.-F. , Blin D. , Martin F. , Marthon S. , Barrett N. T. , Besson P.
Published: October 2002

X-ray photoelectron spectroscopy using synchrotron radiation has been used to investigate the HfO2/SiO2 interface chemistry of high-quality 0.6 and 2.5 nm HfO2/0.6 nm SiO2/Si structures. The high energy resolution (0.15 eV) along with the high brightness level allows us to separate, unambiguously, on both Hf 4f and Si 2p core-level spectra, interfacial Hf–silicate bonds from bulk HfO2 and SiO2 contributions, thus making possible subsequent quantitative treatments and modeling of the interfacial layer structure. Careful assessment of the energy shift of the interfacial components shows that Si-rich Hf silicates are present. The underlying assumption that initial-state contribution dominates the observed Si 2p shift is briefly discussed.
Marketing of agricultural products: case findings
Authors: Hingley Martin , Lindgreen Adam
Published: October 2002

This article focuses on the relationship marketing approach to marketing of agricultural products. The article provides specific insights into, and comparisons between, suppliers of two particular agricultural products sectors: in Britain, the fresh produce (fruits and vegetables) sector and, in New Zealand, the wine sector. The article examines the nature of marketing relationships from the perspective of the suppliers in these sectors and their relationships, networks, and interactions with importers and retail buyers in the food and beverage industry. The research methodology is qualitative and inductive in nature and utilises multiple cases. Interpretation is first through content analysis of each individual case in order to identify important themes, clusters, and patterns in the research data and secondly through across‐case analysis. Investigated marketing issues include the following: nature of relationship marketing, implementation of relationship marketing, and monitoring and measurement of relationship marketing.
Consumer value structures towards supermarket versus farm shop purchase of apples from integrated production in Belgium
Authors: Vannoppen Jan , Verbeke Wim , Van Huylenbroeck Guido
Published: October 2002

This paper compares consumer motivation for buying “Integrated production” certified and labelled apples through either farm shops or supermarkets. The research methodology builds on means‐end‐chain (MEC) theory, with data collected through personal laddering interviews in Belgium. Hierarchical value maps, which visualise motivational structures of supermarket and farm shop purchase of quality labelled apples, are presented. Apple buyers at both outlet types pursue similar values, with health being paramount, but realise those values through largely different MECs. The findings reveal interactions between market channel characteristics and product attributes. Also, the study shows how outlet choice influences the perception and the motivation structure of the respondents for fresh apples. From the findings, implications pertaining to advertising are set forth through the application of the “Means‐end conceptualisation of the components of advertising strategy” or MECCAS model.
Business negotiations in the context of strategic relationship development
Authors: Harwood Tracy
Published: October 2002

Despite a multitude of papers on selling and even negotiation, there has been very limited investigation of what leads to successful negotiation. This paper begins to tackle that shortfall and outlines the findings of exploratory research into negotiation styles of customer‐supplier dyads engaged in strategic relationship development. First, it reviews two distinct styles of negotiation approach: the competitive (adversarial or distributive) approach and the collaborative (problem‐solving or integrative) approach. Then it discusses the findings that support the argument that there are commonalities in the adoption of negotiating stances across industries and at different stages of relationship development. In conclusion the paper suggests that negotiation can be seen as a process of information exchange and highlights the practical implications of this research in terms of business development.
Competitive intelligence in UK firms: a typology
Authors: Wright Sheila , Pickton David W. , Callow Joanne
Published: October 2002

There is a danger of allowing competitive analysis to receive less than adequate attention in the marketing‐planning process as it is subordinated to a customer‐driven focus. Clearly important though customers are, they should not dominate marketing strategy and planning to the exclusion of other influential groups, one of these being competitors. With this in mind, a pilot research project was undertaken to gain a better understanding of how UK companies conduct competitive intelligence. From this pilot, a tentative typology of companies was developed to reflect four attributes of competitive intelligence activity: attitude, gathering, use, and location. Further research was subsequently undertaken to corroborate the findings of the pilot study, test the appropriateness of the typology and further develop the classification definitions. The research has resulted in a typology that illustrates a continuum of behaviour on the four strands of investigation. From this, an understanding of CI best practice can be deduced.
An integrated framework for recommendation systems in e‐commerce
Authors: Shih Timothy K. , Chiu Chuan‐Feng , Hsu Hui‐huang , Lin Fuhua
Published: October 2002

The Internet has become a popular medium for information exchange and knowledge delivery. Several traditional social activities have moved to the Internet, such as distance learning, tele‐medical system and. traditional buying and selling activities. Online merchants must know what users want, so providing recommendation services is an important strategy. Analyzes users’ on‐line behavior and interests, and recommends to them new or potential products. The analysis mechanism is based on the correlation among customers, product items, and product features. An algorithm is developed to classify users into groups and the recommendation is based on the classification. The system can help merchants to make suitable business decisions and provide personalized information to the customers. A generic mobile agent framework for e‐commerce applications is proposed. The aforementioned collaborative computing architecture for the recommendation system is based on the framework.
Analysis of axially polarized piezoelectric ceramic cylindrical shells of finite length with internal losses
Authors: Ebenezer D. D. , Abraham Pushpa
Published: October 2002

A thin shell analytical model of axially polarized piezoelectric ceramic cylinders with internal losses is presented. The Flugge assumptions for strain–displacement relations, Hamilton’s principle extended to piezoelectric shells, and the assumption that electric potential has a quadratic variation between the curved surfaces, are used to derive displacement–potential relations that are similar to equations of motion of elastic shells. A solution, with 12 coefficients, to these relations is then derived. The coefficients are complex when the shell has internal losses and are determined by using three mechanical and three electrical boundary conditions at each end—on the flat surfaces. Computed values of input electrical admittance are presented for shells with and without internal losses, and for thin shells as well as shells with wall thickness comparable to the length. They are also compared with results obtained using the finite element program—ATILA. It is shown that the analytical values of resonance frequencies, the maximum value of input electrical conductance, and the maximum and minimum values of input electrical susceptance of thin shells are in excellent agreement with finite element results. The dependence of the maxima and minima in the complex input electrical admittance on the dimensions of the shell is inferred from the numerical results.
On the existence of flexural edge waves on thin orthotropic plates
Authors: Thompson Ian , Abrahams I. David , Norris Andrew N.
Published: October 2002

This paper is concerned with an investigation into the existence of waves propagating along a free edge of an orthotropic plate, where the edge is inclined at arbitrary angle to a principal direction of the material. After deriving the governing equation and edge conditions, an edge wave ansatz is substituted into this system to reduce it to a set of algebraic equations for the edge wave wave number and wave vector. These are solved numerically for several typical composite materials although analytic expressions can be obtained in the case of special values of the material parameters and inclination angle. It is found that a unique edge wave solution, which generally exhibits oscillation as well as decay away from the free edge, exists in all cases, and its wave speed is independent of its direction of propagation along the plate.
Computational aeroacoustics of phonation, Part I: Computational methods and sound generation mechanisms
Authors: Zhao Wei , Zhang Cheng , Frankel Steven H. , Mongeau Luc
Published: October 2002

The aerodynamic generation of sound during phonation was studied using direct numerical simulations of the airflow and the sound field in a rigid pipe with a modulated orifice. Forced oscillations with an imposed wall motion were considered, neglecting fluid–structure interactions. The compressible, two-dimensional, axisymmetric form of the Navier–Stokes equations were numerically integrated using highly accurate finite difference methods. A moving grid was used to model the effects of the moving walls. The geometry and flow conditions were selected to approximate the flow within an idealized human glottis and vocal tract during phonation. Direct simulations of the flow and farfield sound were performed for several wall motion programs, and flow conditions. An acoustic analogy based on the Ffowcs Williams–Hawkings equation was then used to decompose the acoustic source into its monopole, dipole, and quadrupole contributions for analysis. The predictions of the farfield acoustic pressure using the acoustic analogy were in excellent agreement with results from the direct numerical simulations. It was found that the dominant sound production mechanism was a dipole induced by the net force exerted by the surfaces of the glottis walls on the fluid along the direction of sound wave propagation. A monopole mechanism, specifically sound from the volume of fluid displaced by the wall motion, was found to be comparatively weak at the frequency considered (125 Hz). The orifice geometry was found to have only a weak influence on the amplitude of the radiated sound.
Microphone array measurement system for analysis of directional and spatial variations of sound fields
Authors: Gover Bradford N. , Ryan James G. , Stinson Michael R.
Published: October 2002

A measurement system has been developed that is capable of analyzing the directional and spatial variations in a reverberant sound field. A spherical, 32-element array of microphones is used to generate a narrow beam that is steered in 60 directions. Using an omnidirectional loudspeaker as excitation, the sound pressure arriving from each steering direction is measured as a function of time, in the form of pressure impulse responses. By subsequent analysis of these responses, the variation of arriving energy with direction is studied. The directional diffusion and directivity index of the arriving sound can be computed, as can the energy decay rate in each direction. An analysis of the 32 microphone responses themselves allows computation of the point-to-point variation of reverberation time and of sound pressure level, as well as the spatial cross-correlation coefficient, over the extent of the array. The system has been validated in simple sound fields in an anechoic chamber and in a reverberation chamber. The system characterizes these sound fields as expected, both quantitatively from the measures and qualitatively from plots of the arriving energy versus direction. It is anticipated that the system will be of value in evaluating the directional distribution of arriving energy and the degree and diffuseness of sound fields in rooms.
Source localization in a time-varying ocean waveguide
Authors: Soares Cristiano , Siderius Martin , Jesus Sérgio M.
Published: October 2002

One of the most stringent impairments in matched-field processing is the impact of missing or erroneous environmental information on the final source location estimate. This problem is known in the literature as model mismatch and is strongly frequency dependent. Another unavoidable factor that contributes to model mismatch is the natural time and spatial variability of the ocean waveguide. As a consequence, most of the experimental results obtained to date focus on short source-receiver ranges (usually <5 km), stationary sources, reduced time windows and frequencies generally below 600 Hz. This paper shows that MFP source localization can be made robust to time–space environmental mismatch if the parameters responsible for the mismatch are clearly identified, properly modeled and (time-)adaptively estimated by a focalization procedure prior to MFP source localization. The data acquired during the ADVENT’99 sea trial at 2, 5, and 10 km source-receiver ranges and in two frequency bands, below and above 600 Hz, provided an excellent opportunity to test the proposed techniques. The results indicate that an adequate parametrization of the waveguide is effective up to 10 km range in both frequency bands achieving a precise localization during the whole recording of the 5 km track, and most of the 10 km track. It is shown that the increasing MFP dependence on erroneous environmental information in the higher frequency and at longer ranges can only be accounted for by including a time dependent modeling of the water column sound speed profile.
Orientation effects on linear time-reversing array retrofocusing in shallow water
Authors: Dungan Michael R. , Dowling David R.
Published: October 2002

A time-reversing array (TRA) can retrofocus acoustic energy, in both time and space, to the original sound-source location without any environmental information. This paper presents results from an analytical and computational investigation into the effects that array orientation has on linear TRA retrofocusing in shallow water environments. A linear TRA has three limiting orthogonal orientations with respect to a distant sound source in a shallow water waveguide: vertical, endfire, and broadside. Here, TRA retrofocus characteristics are predicted for monochromatic sound propagation in a Pekeris waveguide using a modal sum Green’s function and in a more realistic sound channel having vertical sound speed variation using a computed Green’s function. Both analytical and computational results are compared for the three orthogonal array orientations with vertical arrays performing best. Differences in TRA retrofocusing performance in the three orientations are primarily determined by geometrical considerations and the extra mode-shape weighting inherent in the back-propagated field of horizontal TRAs.
The photoacoustic effect generated by an incompressible sphere
Authors: Diebold Gerald J. , Beveridge Andrew C. , Hamilton Theron J.
Published: October 2002

An incompressible sphere with a vanishing thermal expansivity suspended in a fluid can generate a photoacoustic effect when the heat deposited in the sphere by a light beam diffuses into the surrounding liquid causing it to expand and launch a sound wave. The properties of the photoacoustic effect for the sphere are found using a Green’s function solution to the wave equation for pressure with Neumann boundary conditions. The results of the calculation show that the acoustic wave for fast heat liberation is an outgoing compressive pulse followed by a reflected pulse whose time profile is modified as a result of frequency dependent reflection from the sphere. For slow heat release by the sphere, the photoacoustic effect is shown to be proportional to the first time derivative of the heat flux at the particle-fluid interface.
Rectified heat transfer into translating and pulsating vapor bubbles
Authors: Hao Y. , Prosperetti A.
Published: October 2002

It is well known that, when a stationary vapor bubble is subject to a sufficiently intense acoustic field, it will grow by rectified heat transfer even in a subcooled liquid. The object of this paper is to study how translation, and the ensuing convective effects, influence this process. It is shown that, depending on the initial temperature distribution and other factors, convection can cause a destabilization of the bubble or its faster growth. Significant effects occur in parameter ranges readily encountered in practice. The phenomena described can therefore be exploited for bubble management, e.g., by increasing the condensation rate or promoting faster bubble growth and coalescence. In a saturated or a superheated liquid, heat rectification and convection reinforce each other and the bubble growth is accelerated by a translatory motion.
Elastic guided waves in a layered plate with rectangular cross section
Authors: Mukdadi O. M. , Desai Y. M. , Datta S. K. , Shah A. H. , Niklasson A. J.
Published: October 2002

Guided waves in a layered elastic plate of rectangular cross section (finite width and thickness) has been studied in this paper. A semianalytical finite element method in which the deformation of the cross section is modeled by two-dimensional finite elements and analytical representation of propagating waves along the length of the plate has been used. The method is applicable to arbitrary number of layers and general anisotropic material properties of each layer, and is similar to the stiffness method used earlier to study guided waves in a laminated composite plate of infinite width. Numerical results showing the effect of varying the width of the plate on the dispersion of guided waves are presented and are compared with those for an infinite plate. In addition, effect of thin anisotropic coating or interface layers on the guided waves is investigated.
Investigating alternative forms of clear speech: The effects of speaking rate and speaking mode on intelligibility
Authors: Krause Jean C. , Braida Louis D.
Published: October 2002

Sentences spoken “clearly” (and slowly) are significantly more intelligible than those spoken “conversationally” for hearing-impaired listeners in a variety of backgrounds [Picheny, Durlach, and Braida, J. Speech Hear. Res. 28, 96–103 (1985); Uchanski et al., J. Speech Hear. Res. 39, 494–509 (1996); Payton, Uchanski, and Braida, J. Acoust. Soc. Am. 95, 1581–1592 (1994)]. However, it is unknown whether slower speaking rates are necessary for highly intelligible speech or whether an alternative form of clear speech exists at faster (i.e., normal) rates. To investigate this question, talkers with significant public speaking experience were asked to produce clear and conversational speech at slow, normal, and quick rates. A method for eliciting clear speech was introduced that ensured the clearest possible speech was obtained at each of these speaking rates. To probe for other highly intelligible speaking modes, talkers also recorded sentences in two other speaking modes: soft and loud. Intelligibility tests indicated that clear speech was the only speaking mode that provided a consistent intelligibility advantage over conversational speech. Moreover, the advantage of clear speech was extended to faster speaking rates than previously reported. These results suggest that clear speech has some inherent acoustic properties that contribute to its high intelligibility without altering rate. Identifying these acoustic properties could lead to improved signal-processing schemes for hearing aids.
Fundamental frequency degeneracy of standing surface acoustic waves under metallic gratings on piezoelectric substrates
Authors: Darinskii A. N. , Biryukov S. V. , Weihnacht M.
Published: October 2002

The paper studies specific features of surface acoustic waves on piezoelectric substrates under infinite periodic grating arrays. The grating is made up of identical metallic electrodes of finite thickness and has one electrode per cell. It has been shown via the analysis of numerical algorithms and the coupling-of-modes equations that one of the fundamental frequencies of the standing wave under short-circuited grating necessarily coincides with one of the fundamental frequencies corresponding to the open-circuited grating if the substrate assumes particular orientations connected with its crystallographic symmetry. The existence of degeneracy does not depend on the material constants of the substrate and the electrode, the thickness of the electrode, and the specific electrode shape provided that the electrode is uniform along the wave normal and shaped symmetrically in the same direction. The proof applies both to ordinary and leaky surface waves.
A broadband tactile array on the fingertip
Authors: Summers Ian R. , Chanter Craig M.
Published: October 2002

A stimulator array is described which can deliver a wide range of displacement waveforms from each contactor, allowing vibratory stimuli to be targeted towards different populations of mechanoreceptors in the skin. The array has a working bandwidth of 20–400 Hz and 100 moving contactors covering an area of 1 cm2 on the fingertip. The array was validated with two experiments on the perception of moving vibratory targets within a uniform background vibration. In the first experiment, with target and background at the same frequency, equivalent discrimination of target movement was obtained at higher values of target/background amplitude ratio for 40-Hz stimuli than for 320-Hz stimuli. In the second experiment, discrimination of target movement within a different-frequency background (320-Hz target and 40-Hz background, or vice versa) was found to be much easier than within a same-frequency background. These results suggest that tactile spatial acuity is better at 320 Hz than 40 Hz and that it is possible to target different receptor populations in the skin by using these frequencies. However, there are problems with this interpretation: on the basis of characterization of touch receptors in previous studies, spatial acuity is expected to be worse at 320 Hz than at 40 Hz.