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We propose a modified polymer reference interaction site model (PRISM) to describe the interfacial density profiles of polymers in contact with planar and curved solid surfaces. In the theoretical approach, a bridge function derived from density functional method is included. In description of hard-sphere polymer at planar and curved surfaces with an arbitrary external field, the effect of modification has been validated by the available simulation data, except for low density system. When extended to confined real systems, the modified theoretical model also shows an encouraging prospect in description of the interfacial structure and properties. [ABSTRACT FROM AUTHOR]

Electric field produced inside a solute by a uniformly polarized liquid is strongly affected by dipolar polarization of the liquid at the interface. We show, by numerical simulations, that the electric 'cavity' field inside a hydrated non-polar solute does not follow the predictions of standard Maxwell's electrostatics of dielectrics. Instead, the field inside the solute tends, with increasing solute size, to the limit predicted by the Lorentz virtual cavity. The standard paradigm fails because of its reliance on the surface charge density at the dielectric interface determined by the boundary conditions of the Maxwell dielectric. The interface of a polar liquid instead carries a preferential in-plane orientation of the surface dipoles thus producing virtually no surface charge. The resulting boundary conditions for electrostatic problems differ from the traditional recipes, affecting the microscopic and macroscopic fields based on them. We show that relatively small differences in cavity fields propagate into significant differences in the dielectric constant of an ideal mixture. The slope of the dielectric increment of the mixture versus the solute concentration depends strongly on which polarization scenario at the interface is realized. A much steeper slope found in the case of Lorentz interfacial polarization also implies a higher free energy penalty for polarizing such mixtures. [ABSTRACT FROM AUTHOR]

This article presents a simulation model that can be used to generate a two-dimensional surface profile which is statistically similar to the actual measured profile in both directions of asperities, amplitudes, and mean line of the profile. The model uses the Ra, AMS, and RMSS values to regenerate the actual surface profile. The generated segments represent samples from the population of profiles which could have been produced under the same machining conditions of the specimen. So, the study of the relation between profiles of surfaces in contact can be made simpler and the variability of results can be evaluated by considering several samples of simulated profiles. Qualitative and quantitative comparison of the parameters and characteristics of simulation with experimental profiles did not detect any significant difference. [ABSTRACT FROM AUTHOR]

The new modified pouring method (copper disc mold simulator, CDMS) to investigate the interfacial thermal resistance and crystallinity for the mold fluxes was introduced. To make sure the formation of the air gap, the surface waviness was measured with the crystallinity. The interfacial thermal resistance increased with higher average waviness, which means the average height of air gap. However, the average waviness did not increase with the higher crystallinity. This result came from the different crystallization mechanisms and the contraction of the flux during the solidification and crystallization was varied based on the crystallization mechanism. Therefore, it is important to apply the mold flux which has optimum crystallization behavior because applying the strong crystallized mold flux to increase the interfacial thermal resistance does not always bring the high interfacial thermal resistance. [ABSTRACT FROM AUTHOR]

On the basis of transformation optics, we propose an approach to couple surface plasmon waves across gaps in a dielectric/metal interface. The coupler employs a slab of complementary medium with negative refraction index to virtually bridge the gap by optically compensating the rest air region in the gap. Several design examples through transformation optics have been demonstrated which could enable plasmonic waves to propagate through two-dimensional gaps in metal surfaces with transversal offset, vertical offset or tilt geometry. The functionality of the proposed couplers has been validated through finite-element method-based full-wave simulations. [ABSTRACT FROM AUTHOR]

Abstract: We extend the computational method presented in for tracking an interface immersed in a given velocity field to three spatial dimensions. The proposed method is particularly relevant to the simulation of unsteady free surface problems using the arbitrary Lagrangian–Eulerian framework, and has been constructed with two goals in mind: (i) to be able to accurately follow the interface; and (ii) to automatically maintain a good distribution of the grid points along the interface. The method combines information from a pure Lagrangian approach with information from an ALE approach. The new method offers flexibility in terms of how an “optimal” point distribution should be defined, and relies on the solution of two-dimensional surface convection problems. We verify the new method by solving model problems both in the single and multiple spectral element case, and we compare this method with other traditional alternatives. We have been able to verify first, second, and third order temporal accuracy for the new method by solving these three-dimensional model problems. [Copyright &y& Elsevier]

Abstract: A three-dimensional (3-D) multiphase-field model has been developed in order to study the formation of a micropore constrained to grow in a solid network (i.e. pinching effect). The model accounts for the pressure difference due to capillarity between liquid and gas, the equilibrium condition at triple (solid–liquid–pore) lines, and the partitioning and diffusion of dissolved gases such as hydrogen. From the predicted 3-D morphology of the pore, entities such as the interfacial shape distribution are plotted and analyzed. It is shown that the mean curvature of the pore–liquid surface, and thus also the pressure inside the pore, is uniform. The results are then compared with analytical pinching models. While predicting a similar trend, analytical models tend to underestimate the pore curvature at high solid fractions. Despite the complex morphology of pores reconstructed using high-resolution X-ray tomography, the present phase-field results suggest that a simple pinching model based on a spherical tip growing in between remaining liquid channels is a fairly good approximation. [Copyright &y& Elsevier]

The structure of block copolymers results from the interplay between weak intermolecular forces, typically in the order of kBT per molecule. This is particularly true for block copolymer thin films in the presence of chemically patterned surfaces, where the different contributions to the total free energy, the interfacial and bulklike terms, have comparable magnitudes. Here, we report on the structures formed by block copolymers films equilibrated between two chemically patterned surfaces with orthogonal stripes. Our experiments and simulations reveal that the domains are continuous through the film and the interface between domains resembles the Scherk's first minimal surface. The impact of chemical patterns on block copolymer morphologies and the underlying physics gives insight into the nanofabrication of complex nanostructures with directed self-assembly using two engineered boundary conditions, as opposed to only one. [ABSTRACT FROM AUTHOR]

Abstract: Using the detailed numerical simulation data of primary atomization, the liquid surface instability development that leads to atomization is characterized. The numerical results are compared with a theoretical analysis of liquid–gas layer for a parameter range close to high-speed Diesel jet fuel injection. For intermittent and short-duration Diesel injection, the aerodynamic surface interaction and transient head formation play an important role. The present numerical setting excludes nozzle disturbances to primarily investigate this interfacial instability mechanism and the role of jet head. The first disturbed area is the jet head region, and the generated disturbances are fed into the upstream region through the gas phase. This leads to the viscous boundary layer instability development on the liquid jet core. By temporal tracking of surface pattern development including the phase velocity and stability regime and by the visualization of vortex structures near the boundary layer region, it is suggested that the instability mode is the Tollmien–Schlichting (TS) mode similar to the turbulent transition of solid-wall boundary layer. It is also demonstrated that the jet head and the liquid core play an interacting role, thus the jet head cannot be neglected in Diesel injection. In this study, this type of boundary layer instability has been demonstrated as a possible mechanism of primary atomization, especially for high-speed straight liquid jets. The effect of nozzle turbulence is a challenging but important issue, and it should be examined in the future. [Copyright &y& Elsevier]

Based on a detailed analysis of DEM simulation data,this paper provides new insights into the effects of boundary surface topography on the mobilized stress ratio and stress-displacement behavior in the interface shear test and the direct shear test. The soil mechanics observed in the two types of tests are unified under a novel perspective of boundary-induced soil behavior. It is shown that the principal direction of the contact force anisotropy developed at the soil-surface boundary has an exclusive control over the peak stress ratio measured both at the boundary and inside the sampling window. However, a subtle change in the roles of the principal direction and the magnitude of contact force anisotropy is found as the contact force chains extend from the surface into the interphase soil. [ABSTRACT FROM AUTHOR]

It is shown that the resonance features analogous to the well known optic Wood-type anomalies can be observed in the THz region for diffraction at periodically profiled semiconductor surfaces. The analytical theory of such resonance processes caused by excitation of surface plasmon polaritons (SPPs) is developed. It is shown that strong resonance effects such as total suppression of the specular reflection (TSSR) can be achieved for rather small inclinations of harmonic gratings. The analytical theory predictions are confirmed by strict numerical simulations. The analytical approach presented allows one to find parameters of the gratings so that the resonance diffraction results in specific redistributions of the reflected energy between different diffraction channels. As an example we demonstrate parameters of the InSb biharmonic grating responsible for the TSSR accompanied by 50% reflection in the minus first diffraction order when the SPP is excited in the plus first diffraction order. [ABSTRACT FROM AUTHOR]

Abstract: The numerical modeling of interaction between oxygen high-pressure jets and a liquid–metal surface in a steel-making converter, where, under the force action of the jets, a cavern with a hydrodynamically unstable surface forms in the metal bulk, is studied. A simplified scheme of chemical reactions and mechanisms of metal-drop dispersing from the interface between the phases is proposed. This scheme permits an adequate description of the hydrodynamic flow pattern in the cavern. The modeling of a two-phase turbulent flow in the cavern is considered within the framework of the continuum model based on the averaged Navier–Stokes equations. To close the equations, a modified k–ε turbulence model is used, which takes into account the presence of the second phase. The flow structure in the cavern is studied. Practical recommendations for increasing the efficiency of the carbon-monoxide afterburning process in the cavern are given. [Copyright &y& Elsevier]

Hysteresis of wetting, like the Coulombic friction at solid/solid interface, impedes the motion of a liquid drop on a surface when subjected to an external field. Here, we present a counterintuitive example, where some amount of hysteresis enables a drop to move on a surface when it is subjected to a periodic but asymmetric vibration. Experiments show that a surface either with a negligible or high hysteresis is not conducive to any drop motion. Some finite hysteresis of contact angle is needed to break the periodic symmetry of the forcing function for the drift to occur. These experimental results are consistent with simulations, in which a drop is approximated as a linear harmonic oscillator. The experiment also sheds light on the effect of the drop size on flow reversal, where drops of different sizes move in opposite directions due to the difference in the phase of the oscillation of their center of mass. [ABSTRACT FROM AUTHOR]

Abstract: We investigated structures derived from and ZSM-5-crystallites in different orientations and combinations. Gaps are introduced into the configurations in order to produce surfaces. However, interfaces can be formed by coalescence of surfaces. The structural and thermal properties of the thus generated interfaces and of the remaining surfaces are qualitatively discussed. Applying different sizes of the gaps between the structures allowed the monitoring of structural changes, partial pair-correlation functions and bond-angle distributions. Furthermore, we discuss the influence of the thermal or temperature distribution in the thus constructed materials. We report about the qualitative differences using both constant temperatures and temperature gradients. [Copyright &y& Elsevier]

Abstract: Classical molecular dynamics simulations have been carried out to investigate the development of surface topographies following irradiation by swift heavy ions. Two models were used: a thermal spike model in which atoms within a cylinder surrounding the path of the ion are given kinetic energy due to the electronic energy loss of the particle; and an electron stripping with recombination model. Both models give qualitatively similar results and show the formation of hillocks on the surface above the ion track and a less dense track core near to the surface. [Copyright &y& Elsevier]

We investigate the nonlinear wave signature of a translating and oscillating disturbance under the influence of ambient waves in a two-layer fluid. The main interests are the generation and features of the far-field waves due to nonlinear wave resonances. We show, using perturbation theory, that free waves on the surface and/or interface can be produced by triad-resonant interactions, a mechanism not obtained in a homogeneous fluid. These occur among the radiated waves due to the disturbance motion (disturbance waves); and between the disturbance waves and free ocean waves (ambient waves). Such resonance-generated waves can appear upstream or downstream, and may propagate away from or towards the disturbance. In realistic situations where ambient waves and disturbance oscillations contain multiple frequencies, numerous resonant and near-resonant interactions at second and higher orders may occur, making the theoretical analysis of the problem intractable. For this purpose, we develop a direct simulation capability using a high-order spectral method, which provides independent validation of the theoretical predictions. Our investigations show that, under specific but realistic conditions, resonance interactions may lead to significant far-field short waves that are more amenable to remote sensing. If the characteristics of the disturbance are known, we illustrate how nonlinear wave resonances provide a mechanism for more precise estimation of ocean stratification properties using surface wave measurements. Finally we show that when a moving disturbance oscillates at multiple frequencies, ensuing multiple resonances may lead to energy spreading across a broader spectrum, resulting in the loss of information about the body motion. [ABSTRACT FROM PUBLISHER]

Abstract: Surface nucleation of poly(l/d-lactide) at the interface with aluminum was studied by performing isothermal DSC analysis of amorphous samples of varying thickness between 100 °C and 130 °C. To ensure complete wetting of the aluminum surface, a hot melt laminating process was used to prepare the samples. Theoretical aspects of surface crystallization kinetics were explored and the resulting model was compared with the results of Monte-Carlo simulations. Three stages of surface crystallization were identified depending on the growth geometry: (1) impingement-free growth, (2) increasingly laterally-constrained transverse growth, and (3) interstitial growth. By fitting the Monte-Carlo simulation to the experimental half-times of crystallization the surface nucleation concentration and the bulk nucleation rate was estimated at 4 different temperatures. It was found that both surface nucleation concentration and the bulk nucleation concentration decrease with increasing crystallization temperature. [Copyright &y& Elsevier]

Abstract: The objective of this work is to investigate the coupling of fluid dynamics, heat transfer and mass transfer during the impact and evaporation of droplets on a heated solid substrate. A laser-based thermoreflectance method is used to measure the temperature at the solid–liquid interface, with a time and space resolution of 100μs and 20μm, respectively. Isopropanol droplets with micro- and nanoliter volumes are considered. A finite-element model is used to simulate the transient fluid dynamics and heat transfer during the droplet deposition process, considering the dynamics of wetting as well as Laplace and Marangoni stresses on the liquid–gas boundary. For cases involving evaporation, the diffusion of vapor in the atmosphere is solved numerically, providing an exact boundary condition for the evaporative flux at the droplet–air interface. High-speed visualizations are performed to provide matching parameters for the wetting model used in the simulations. Numerical and experimental results are compared for the transient heat transfer and the fluid dynamics involved during the droplet deposition. Our results describe and explain temperature oscillations at the drop–substrate interface during the early stages of impact. For the first time, a full simulation of the impact and subsequent evaporation of a drop on a heated surface is performed, and excellent agreement is found with the experimental results. Our results also shed light on the influence of wetting on the heat transfer during evaporation. [Copyright &y& Elsevier]

Abstract: We introduce experimental results that reveal a small static and a slowly varying-dynamic magnetic field B induces a magneto-modulation of the gate leakage current of a 65nm nMOSFET. For the case of a 100mT (mili-Tesla) static B field a variation of the 6% (1.5nA/27nA) of the gate current is observed. For a 5Hz slowly varying (±100mT) square pulsed magnetic field, the gate current dynamic variation raises up to 18% (4.8nA/27nA). These experimental observations are explained in terms of space and time modulation of the two-dimensional surface inversion layer charge. The static B field dependent model is validated through Minimos-NT numerical simulations, while the dynamic B field experimental observations are reproduced with a SPICE macro-model, which uses the static device model as initial condition for the dynamic model. With this model we are able to predict the impact of small static and dynamic B fields on the gate leakage current and channel current interference of low-dimensional MOS transistors. We also propose this electro-magnetic experimental technique as an alternative for detailed exploration of the Si–SiO2 interface properties for 2nm or thinner gate oxides, as well as for low-dimensional semiconductor devices. [Copyright &y& Elsevier]

Abstract: Geometrical and surface effects can significantly alter conduction through metal/semiconductor nanowire (NW) contacts. In this study, we use three dimensional device simulations to examine these effects in detail. Based on the results of these simulations, a methodology is proposed for the extraction of Schottky barrier heights of contacts to semiconductor nanowires. The Schottky barrier height extracted from the current–voltage (I–V) characteristics can differ from the true barrier height due to tunneling contributions localized at the metal/nanowire interface along the nanowire periphery. The outlined method is used to analyze experimental I–V characteristics of a surround-gate axially-aligned nanowire Schottky barrier contact. [Copyright &y& Elsevier]

Abstract: Molecular dynamics computer simulation of the surface of water–methanol mixtures containing only traces (i.e., 3%, 5% and 10%) of water are performed on the canonical (N,V,T) ensemble at 298K. The properties of the surface are analyzed in terms of the novel ITIM method. The obtained results show that the vicinity of the vapor phase only affects the properties of the first molecular layer, and vanishes beyond this layer. No region of water adsorption/methanol depletion is observed. The methanol molecules are found to be in an excess number at the surface (relative to the bulk liquid phase), and are found to stay considerably longer at the surface layer than the water molecules. In their preferred alignment surface methanols are found to stay perpendicular to the macroscopic plane of the surface, sticking their CH3 group straight to the vapor phase. [Copyright &y& Elsevier]

Abstract: The influence of interfacial structure on interfacial properties between activated carbon filler and surrounding organic matrix of composites has been studied by infrared and NMR spectroscopy. Urea, semicarbazide and ethylurethane, component parts of polyurethane, have been used as organic model compounds in order to predict the interactions between the activated carbon surface and polar groups of real polyurethane molecule. It was shown that organic matrix/activated carbon interphase presented a region where the filler and matrix phases were chemically and/or physically combined. The spectra of the organic matrix undergo significant changes with increase of carbon content. Due to the surface reactive functionalities the activated carbon is considered not only as filler, influenced on the sorption properties of the composition, but also as a physicochemical modifier of the polyurethane matrix. [Copyright &y& Elsevier]

Abstract: In this paper, we present a hybrid volume-of-fluid-based algorithm for the simulation of free-surface-flow problems. For the solution of the flow field, the lattice Boltzmann method is used. The additional advection equation for the volume-of-fluid (VOF) fill level is discretized with a classical finite volume method. For the interface reconstruction, a piecewise linear interface reconstruction in 3D has been implemented. The free-surface-tracking algorithm is embedded into the 3D, non-uniform, lattice-Boltzmann-based solver VirtualFluids; Freudiger et al. (2009) , Freudiger (2009) . The advection algorithm is verified and validated with well-known advection test cases. For the validation of the free-surface algorithm, we present simulations of a breaking-dam benchmark. [Copyright &y& Elsevier]

Experimental evidence suggests dissolution along the polar caxis of αresorcinol in water preferentially occurs at the {011} surface. In an attempt to understand the mechanism by which solvent influences this process, dissolution at the resorcinol {0$ \bar 1 $$ \bar 1 $} and {0$ \bar 1 $$ \bar 1 $} surfaces has been studied using Molecular Dynamics simulations. Our computations indicate dissolution at the two faces is dependent upon solvent behaviour at the crystal surface, where strong watercrystal interactions serve to stabilise the crystal surface and retard dissolution. © 2010 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim [ABSTRACT FROM AUTHOR]

Abstract: As the fine particles expose to the rarefied regimes, the solid-surface effects become prominent and change the interfacial interactions between the gas and particle. The particle drag force, which is mainly concerned in aerosol researches, is affected through the changes observed in the way that fluid entities reflect from the particle surface. A 3D simulation study for an incompressible rarefied slip flow past a spherical aerosol particle was performed. The full Navier–Stokes equations were solved and the velocity jump at the gas–particle interface was treated numerically by imposition of the slip boundary condition. Analytical solution to the Stokesian slip flow past a spherical particle was used as a benchmark for code verification, and reasonable agreement was achieved. The simulation results showed that in addition to the Knudsen number, the Reynolds number affects the slip correction factor. Thus, the Cunningham-based slip corrections must be augmented by the inclusion of the effect of Reynolds number for application to Lagrangian tracking of fine particles. A novel expression for the surface-slip correction factor as a function of both Knudsen number (0.01< Kn <0.1) and Reynolds number (0< Re <1) was developed. [Copyright &y& Elsevier]

Abstract: We present a new method for tracking an interface immersed in a given velocity field which is particularly relevant to the simulation of unsteady free surface problems using the arbitrary Lagrangian–Eulerian (ALE) framework. The new method has been constructed with two goals in mind: (i) to be able to accurately follow the interface; and (ii) to automatically achieve a good distribution of the grid points along the interface. In order to achieve these goals, information from a pure Lagrangian approach is combined with information from an ALE approach. Our implementation relies on the solution of several pure convection problems along the interface in order to obtain the relevant information. The new method offers flexibility in terms of how an “optimal” point distribution should be defined. We have proposed several model problems, each with a prescribed time-dependent velocity field and starting with a prescribed interface; these problems should be useful in order to validate the accuracy of interface-tracking algorithms, e.g., as part of an ALE solver for free surface flows. We have been able to verify first, second, and third order temporal accuracy for the new method by solving these two-dimensional model problems. [Copyright &y& Elsevier]

Abstract: Robust and accurate schemes are designed to simulate the coupling between subsurface and overland flows. The coupling conditions at the interface enforce the continuity of both the normal flux and the pressure. Richards’ equation governing the subsurface flow is discretized using a backward differentiation formula and a symmetric interior penalty discontinuous Galerkin method. The kinematic wave equation governing the overland flow is discretized using a Godunov scheme. Both schemes individually are mass conservative and can be used within single-step or multi-step coupling algorithms that ensure overall mass conservation owing to a specific design of the interface fluxes in the multi-step case. Numerical results are presented to illustrate the performances of the proposed algorithms. [Copyright &y& Elsevier]

Abstract: The characterization of frictional phenomena at the tool–chip–workpiece interface remains an issue. This paper aims to identify a friction model able to describe the friction coefficient at this interface during the dry cutting of a AISI4142 treated steel with TiN coated carbide tools. A new tribometer has been designed in order to reach relevant values of pressures, temperatures and sliding velocities. This set-up is based on a modified pin-on-ring system. Additionally a numerical model simulating the frictional test has been associated in order to identify local phenomena around the spherical pin, from the standard macroscopic data provided by the experimental system. A range of cutting speeds and pressures has been investigated. It has been shown that the friction coefficient is mainly dependant on the sliding velocity, whereas the pressure has a secondary importance. Moreover a new key parameter has been revealed, i.e. the average local sliding velocity at the contact. Finally a new friction model has been identified based on this local sliding velocity. [Copyright &y& Elsevier]

Molecular modeling simulations reveal the role of stereogenic centers in the formation of enantiomorphoussurface-confined supramolecular rosette-like assemblies in monolayers of oligophenylene vinylene oligomers adsorbed at the graphite/solvent interface. [ABSTRACT FROM AUTHOR]

Control of friction is one of the most practical problems in our daily life, which covers almost all the areas from basic science such as physics, chemistry and biology, to industrial technology such as mechanical and material engineering and energy problems. Recently, attempts have been made to use carbon materials as electronic, optical and mechanical devices. In this paper, we briefly explain the basic concept of atomic-scale friction and discuss our recent experimental and simulation studies on nanotribology at carbonic interfaces formed by graphene and fullerene. [Copyright &y& Elsevier]

1D and 2D PIC simulations of light ion acceleration by irradiation of structured thin foils by short pulse, high intensity lasers have been performed. When the back coating material is thicker than the typical scale length for TNSA fields the ion energy spectra contain peaks. These peaks are found to be due to the acceleration of ions by an electric field which builds up at internal interfaces between materials with different electron number densities. The electric field is generated by incomplete neutralization of the charge built up at the head of the hot electron beam as it crosses the interface between the two materials. In these simulations the back material layer is sufficiently thick that the sheath field drops to zero before reaching the vacuum boundary. The acceleration responsible for the peaks is therefore from within the material and is superimposed on the normal TNSA acceleration from the back material-vacuum surface, i.e. there are two distinct sites of particle acceleration. It is possible that this mechanism may explain features previously observed in simulations. A comparison is also made with experiments with thick rear coatings. [ABSTRACT FROM AUTHOR]

By using a semi-empirical Lennard-Jones embedded-atom-method potential, we study the influence of many-body forces and atomic size mismatch on the wetting behavior of nano droplets on a solid surface. With molecular dynamics simulations, we find that the contact angle decreases with increasing many-body forces. The increase of atomic size mismatch between solid and liquid results in the decrease of contact angles. Our calculation also shows that the interface structure is strongly affected by the interaction between liquid and solid as well as the atomic size mismatch. For weak solid-liquid interaction, the interface layer of the droplet nearest to the solid exhibits a typical simple liquid structure regardless of the size mismatch. For strong solid-liquid interaction, evident ordering in the interface layer is observed for well matched cases. [ABSTRACT FROM AUTHOR]

A computational simulation is conducted to investigate the influence of Rayleigh-Taylor instability on liquid propellant reorientation flow dynamics for the tank of CZ-3A launch vehicle series fuel tanks in a low-gravity environment. The volume-of-fluid (VOF) method is used to simulate the free surface flow of gas-liquid. The process of the liquid propellant reorientation started from initially flat and curved interfaces are numerically studied. These two different initial conditions of the gas-liquid interface result in two modes of liquid flow. It is found that the Rayleigh-Taylor instability can be reduced evidently at the initial gas-liquid interface with a high curve during the process of liquid reorientation in a low-gravity environment. [ABSTRACT FROM AUTHOR]