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Reasonable design and effective detection of the random access preamble has become a challenging task due to the unique characteristics of mobile satellite communications. To tackle this challenge, we first design a universal long sequence structure by concatenating multiple short Zadoff–Chu sequences that are insensitive to carrier frequency offset (CFO), and then propose the new principles of parameter selection for short sequences to ensure the minimum utilization of root sequence and the independence of the cyclic shift offset on the beam radius. To further reduce the detection complexity and improve the multi-user access performance, a fast timing detection approach is also presented by leveraging the piecewise cumulative detection and the multi-peaks joint estimation to obtain an accurate timing advance for each access user. Simulation results and complexity analysis validate the effectiveness of the new preamble in a typical satellite communication environment, and reveal that the proposed timing detection can achieve the robustness to CFO and offer outstanding performance improvements especially in multi-user scenarios while having a notably reduced computational complexity. [ABSTRACT FROM PUBLISHER]

The activity and decay heat inventories were assessed for the HCPB DEMO blankets making use of a code system that enables performing 3D activation calculations by linking the Monte Carlo transport code MCNP and the fusion inventory code FISPACT through an appropriate interface. The dedicated full scale geometry MCNP model of a 10° HCPB DEMO torus was adapted to the requirements for the coupled 3D neutron transport and activation calculations. The sensitivity analyses were performed to assess the effect of the homogenized geometry cells to the final results. The importance of the use of the impurities in the material definitions was pointed out and accounted for in the simulations. The activity of the HCPB blanket modules is dominated by the tungsten protecting layer up to one month after shutdown. After that it’s dominated by the breeding zone mixture of Eurofer, breeder ceramic and beryllium pebbles with impurities. The decay heat generation in blankets is especially high in the casing that requires intensive cooling efforts for their treatment after the shutdown. The accumulation of the poisoning 239 Pu could make complicated the recycling of the beryllium pebbles extracted from the blankets. [ABSTRACT FROM AUTHOR]

In this paper, an accurate front-end CMOS interface circuit for sensing very small capacitance changes in capacitive sensors is presented. The proposed structure scales capacitance variation to the sensible impedance changing. The scaling factor of the circuit can be easily tuned by adjusting bias points of the transistors. In order to cancel or decrease the parasitic components, the RC feedback and input transistor cascading techniques are employed in the design. To simulate the circuit, HSPICE simulator is utilized to verify the validity of the theoretical formulations in 0.18 $$\upmu \hbox {m}$$ technology. According to schematic and post-layout simulation results, input impedance changes linearly versus capacitance variations up to 0.7 GHz, while the sensor capacitance changing is varied between 0 and 200 fF. According to the simulation results, total dc power consumption is obtained as low as 1 mW with 0.9 V power supply. [ABSTRACT FROM AUTHOR]

The stress and strain distribution around the reinforced particles in Al/TiC composites is investigated in this work. It is found that there is a region with higher strain in the matrix along the loading path under the tensile load, which can promote the formation of a void near the particles. And the location of the highest strain is not in but away from the interface in the models with the perfect interface. The distance of the location of the strain peak from the interface is relevant to the size of the particles and the ratio between the distance of the location of the strain peak from the interface and the radius of the particle is close to 0.3. The influence of volume fraction and load on distribution of strain and stress around the particles is diverse in different regions of the matrix. The average strain of the matrix region (Matrix A) which is under the particle mapping along the tensile direction tends to increase with the increasing of the volume fraction, so is the load. Besides that, the main strain bearing part in matrix is gradually transferred from Matrix A to the other region near the particles when the interface becomes weaker. And the location of strain peak along the loading path will be much closer to the interface with the decrease of the interface strength. [ABSTRACT FROM AUTHOR]

The active interface debonding detection for concrete-filled steel tubes (CFSTs) using Piezoelectric Lead Zirconate Titanate (PZT) patches has been proposed and experimentally studied in recent years. In order to further investigate the guided wave propagation and the response of embedded PZT sensor, transient dynamic analysis on multi-physical field coupling models composed of surface-mounted PZT actuator, embedded PZT sensor and a circular CFST specimen considering the coupling effect between the PZT patches and CFST member and the influence of interface debonding defects is carried out numerically. The guided wave propagation within the CFST-PZT coupling system without and with interfacial debonding defects under single period impulse signal is simulated and compared. The voltage response time history of the embedded PZT sensor in coupling models under both sinusoidal and sweep frequency sinusoidal excitations are simulated as an alternative solver. Numerical results demonstrate that interface debonding leads to changes in guided wave propagation path, traveling time and the PZT sensor response. The sensitivity of a quantitative evaluation index called as the normalized wavelet packet energy of the output voltage of embedded PZT sensor to the initiation of interface debonding defect and its length and depth is illustrated. [ABSTRACT FROM AUTHOR]

The austenite/martensite (fcc/bcc) interface is prevalent across many new classes of high-strength steels, and yet both its fundamental structure and its mechanism of motion remain uncertain in spite of decades of research. Here, atomistic simulations are used to create an fcc-bcc iron interface having a structure and motion that match the major experimental observations on dislocated lath martensite. The simulated interface reveals a defect structure and a mechanism of glissile and athermal propagation that differ in important respects from longstanding assumptions. The atomistically-observed interface defects provide a basis for a parameter-free predictive crystallographic double-shear theory of lath martensite. Predictions of the theory match simulations well and yield very good agreement with experiments on Fe-Ni-Mn and Fe-C. The theory shows that the fcc/bcc lattice parameter ratio is the dominant factor for controlling the “shape” deformation – the overall, in-situ strain associated with the martensitic transformation – which is related to macroscopic toughening, and quantitatively rationalizes many experimental observations. This new understanding about the nature of this special interface provides fundamental insights needed for guiding design of emerging high-strength steels. [ABSTRACT FROM AUTHOR]

In this paper, an indirect decoupling method is established to simulate the physical process of an electromagnetic launch considering electromagnetic force, thermo-softening of metallic material, and melting interface layer effects. The dynamic responses of cambered surface rail and armature under electromagnetic and thermal loads are analyzed and a simulation method is provided for the engineering applications of electromagnetic launch technology. [ABSTRACT FROM PUBLISHER]

The atomic scale interfacial microstructure evolution and heat dissipation process in nanoscale friction are investigated by 3D non-equilibrium molecular dynamics (MD) simulations. Two Ni blocks of different orientations are built to simulate the self-mate friction. The embedded atom (EAM) potentials are employed in these simulations. The microstructure evolution is observed. The temperature and velocity profiles along the height direction, which is perpendicular to the direction of motion, are calculated under sliding velocity. The heat dissipation process is studied. The effect of sliding velocity is also obtained. The results show that extensive plastic deformation and temperature rise occur in the interface. Atomic scale mechanical mixing and generation of mixing layer are observed in the regions near the contact interface. The sliding velocity has great impact on temperature rise. The study of the growth dynamics of mixing layer also sheds light on the formation process of mixing layer. [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]

Multi-material lightweight designs, e.g. the combination of aluminum with fiber-reinforced composites, are a key feature for the development of innovative and resource-efficient products. The connection properties of such bi-material interfaces are influenced by the geometric structure on different length scales. In this article a modeling strategy is presented to study the failure behavior of rough interfaces within a computational homogenization scheme. We study different local phenomena and their effects on the overall interface characteristics, e.g. the surface roughness and different local failure types as cohesive failure of the bulk material and adhesive failure of the local interface. Since there is a large separation in the length scales of the surface roughness, which is in the micrometer range, and conventional structural components, we employ a numerical homogenization approach to extract effective traction-separation laws to derive effective interface parameters. Adhesive interface failure is modeled by cohesive elements based on a traction-separation law and cohesive failure of the bulk material is described by an elastic-plastic model with progressive damage evolution. [ABSTRACT FROM AUTHOR]

This study characterizes the interfaces of Al-steel joints generated by resistance spot welding (RSW) processes. Two types of intermetallic compound (IMC) layers at the interface are characterized and discussed. The first type, located in central area of the interface, is composed of tongue-like Fe 2 Al 5 adjacent to the steel and serrated-like FeAl 3 adjacent to the Al; the second type, a mixture of FeAl 3 and Al, lies in the periphery of the joint interface. Formation mechanisms of the two types of IMC layer observed are proposed and discussed in the paper. The thickness distributions of the IMC layer generated by different welding parameters are predicted based on the dynamic interfacial temperature histories from Al-steel RSW process simulation. The predicted IMC thickness distributions are validated against physical measurements and show good agreement. A bimodal IMC thickness distribution is found when an adequately long welding time is applied. This is found to be related to lower interfacial temperature at the center of Al-steel interface than what in the surrounding area after about 200 ms of welding due to strong cooling effect by the electrode. [ABSTRACT FROM AUTHOR]

We review our simulation results on properties of supercooled confined water. We consider two situations: water confined in a hydrophilic pore that mimics an MCM-41 environment and water at interface with a protein. The behavior upon cooling of the a relaxation of water in both environments is well interpreted in terms of the Mode Coupling Theory of glassy dynamics. Moreover, we find a crossover from a fragile to a strong regime. We relate this crossover to the crossing of theWidom line emanating from the liquid-liquid critical point, and in confinement we connect this crossover also to a crossover of the two body excess entropy of water upon cooling. Hydration water exhibits a second, distinctly slower relaxation caused by its dynamical coupling with the protein. The crossover upon cooling of this long relaxation is related to the protein dynamics. [ABSTRACT FROM AUTHOR]

We investigate segregation behavior of additional elements M (=Ni, Co, Ta) at the C11 b /D8 m interface for MoSi 2 –Mo 5 Si 3 alloys, based on first-principles calculation. We first find energetically stable interface structure with interface energy of 0.08 eV/Å 2 (1.3 J/m 2 ). Based on the stable interface, segregation energy for additional elements is calculated for individual atomic layer, which is applied to Monte Carlo statistical simulation under grand-canonical ensemble to quantitatively predict interface segregation profile. We find that our simulation successfully captures the characteristics in measured segregation tendency of (i) similarity in strong segregation at interface both for Ni and Co compared with bulk composition while Ta does not exhibit interface segregation and (ii) stronger segregation for Ni than for Co. The present results indicate that measured segregated interface for MoSi 2 –Mo 5 Si 3 alloys can be thermodynamically stable. [ABSTRACT FROM AUTHOR]

Following our previous work on the application of the diffuse interface coupled lattice Boltzmann-level set (LB-LS) approach to benchmark computations for 2D rising bubble simulations, this paper investigates the performance of the coupled scheme in 3D two-phase flows. In particular, the use of different lattice stencils, e.g., D3Q15, D3Q19 and D3Q27 is studied and the results for 3D rising bubble simulations are compared with regard to isotropy and accuracy against those obtained by finite element and finite difference solutions of the Navier–Stokes equations. It is shown that the method can eventually recover the benchmark solutions, provided that the interface region is aptly refined by the underlying lattice. Following the benchmark simulations, the application of the method in solving other numerically subtle problems, e.g., binary droplet collision and droplet splashing on wet surface under high Re and We numbers is presented. Moreover, implementations on general purpose GPUs are pursued, where the computations are adaptively refined around the critical parts of the flow. [ABSTRACT FROM AUTHOR]

The reactive diffusion concept represents an approved handy tool for simulation of diffusive phase transformations in binary systems. The local value of the site fraction of a particular component, obtained by solution of diffusion equation, determines its affiliation to a phase or to an interface, to which the respective chemical potentials and kinetic coefficients, used in diffusion equation, can be assigned. The reactive diffusion concept is now generalized to account for intensity of non-ideal sources and sinks for vacancies, which allows the treatment of the Kirkendall effect and an according prediction of formation of pores. The new concept is demonstrated on an instructive example showing the kinetics of phase transformation, shift of the Kirkendall plane and evolution of site fraction profiles. Local supersaturation by vacancies indicates the possible formation of pores. [ABSTRACT FROM AUTHOR]

The continuous-feeding Czochralski method is an effective method to reduce the cost of single crystal silicon. By promoting the crystal growth rate, the cost can be reduced further. However, more latent heat will be released at the melt-crystal interface under a high crystal growth rate. In this study, a water-cooled jacket was applied to enhance the heat transfer at the melt-crystal interface. Quasi-steady-state numerical calculation was employed to investigate the impact of the water-cooled jacket on the heat transfer at the melt-crystal interface. Latent heat released during the crystal growth process at the melt-crystal interface and absorbed during feedstock melting at the feeding zone was modeled in the simulations. The results show that, by using the water-cooled jacket, heat transfer in the growing crystal is enhanced significantly. Melt-crystal interface deflection and thermal stress increase simultaneously due to the increase of radial temperature at the melt-crystal interface. With a modified heat shield design, heat transfer at the melt-crystal interface is well controlled. The crystal growth rate can be increased by 20%. [ABSTRACT FROM AUTHOR]

In the present study, a new method for simulation of the conjugate heat transfer conditions at the curved interface of two media with different thermal properties is proposed based on the ghost fluid lattice Boltzmann method (GF-LBM). The proposed method significantly benefits from the inherent feature of the GF-LBM in availability of the temperature gradient normal to the interface. To test the accuracy of the presented method, three different case studies are simulated. The results revealed the second-order accuracy of the proposed conjugate heat transfer formulation. Furthermore, when compared to the available analytical solutions, the results of this study showed better agreement compared to the results of the other available methods. [ABSTRACT FROM PUBLISHER]

Conventionally, the universality class of a discrete growth model is identified via the scaling of interface width. This method requires large-scale simulations to minimize finite-size effects on the results. The multiple hit noise reduction techniques ( m > 1 NRT) and the long surface diffusion length noise reduction techniques ( ℓ > 1 NRT) have been used to promote the asymptotic behaviors of the growth models. Lately, an alternative method involving comparison of roughness distribution in the steady state has been proposed. In this work, the roughness distribution of the (2 + 1)-dimensional Das Sarma–Tamborenea (DT), Wolf–Villain (WV), and Larger Curvature (LC) models, with and without NRTs, are calculated in order to investigate effects of the NRTs on the roughness distribution. Additionally, effective growth exponents of the noise reduced (2 + 1)-dimensional DT, WV and LC models are also calculated. Our results indicate that the NRTs affect the interface width both in the growth and the saturation regimes. In the steady state, the NRTs do not seem to have any impact on the roughness distribution of the DT model, but it significantly changes the roughness distribution of the WV and LC models to the normal distribution curves. [ABSTRACT FROM AUTHOR]

Commercial-scale extraction of methane gas from subsea methane hydrate is difficult. A major challenge is mud erosion at the interfaces of sand–mud alternate layers in the subsea strata. Without a clear understanding of the various parameters associated with mud erosion, there may be complications in developing methane hydrate deposits, such as reservoir clogging due to mud particles. This study aims to develop a numerical simulation method to predict mud erosion caused by water flow in pore-scale computational domain. Microscopic sand beds were generated numerically in the computational domain while the water flow through the pores of various-shaped sand grains was numerically simulated using the lattice Boltzmann method. Mud was treated as a continuum and eroded at its surface via the shear stress of water flow using the critical shear stress and erosion rate constant, which were estimated by fitting calculated erosion rates with those of a laboratory-scale experiment. Using this numerical model, simulations of long-term mud erosion were conducted. The simulation showed that when the average velocity of water in the pore space is larger than the critical value and smaller than ten times that value, the erosion rate is almost zero after about 10 days. [ABSTRACT FROM AUTHOR]

Material flow during welding is an important factor that affects the quality of friction stir welding (FSW) joints. In this study, a new welding tool/work piece contact model is proposed to simulate material flow near the FSW tool. The material around the tool flows under the driving force of friction non-uniformly distributed on the interface. Friction force is calculated based on modified Coulomb friction law in this model. Wormhole defects under various welding parameters are graphically predicted by the distribution of tracing particles added in numerical models. Five groups of FSW experiments were conducted to obtain temperature and joint morphology results. Simulation results, including temperature and wormhole defects prediction, corresponded with the experimental results. Further analyses imply that under the process parameters selected in this study, an area with very low friction force occurred behind the tool pin. When the material in front of the tool pin moved to this area from the retreating side, the material speed significantly decreased due to the insufficient driving force, and it became difficult for the material to move to the advancing side along the circular path. The study reveals that the non-uniform friction force model provides a potential tool for predicting FSW defects. [ABSTRACT FROM AUTHOR]

A VOF-based approach for the detailed computation of reactive mass transfer at rising gas bubbles is presented. Based on a local approximation of the transport equation at the fluid interface, a reactive subgrid-scale model for uncoupled reactions within the concentration boundary layer is derived. For this purpose, the convective term of the boundary layer description is modeled, reducing the governing nonlinear partial differential equation to a one-dimensional nonlinear differential equation. A numerical scheme is developed to solve the remaining differential equation and obtain the concentration gradient at the fluid interface. Mesh convergence for the resulting scheme is shown. The method is validated within the VOF code FS3D by comparing to local and integral Sherwood numbers, and Schmidt numbers up to 1000 for a 3D reactive Stokes flow regime around a rising spherical bubble (Hadamard–Rybczynski flow field). Local Sherwood numbers show significant reactive mass transfer into the liquid phase in the wake region of the rising bubble. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are used to study the structure of the vapor–liquid interface of three-dimensional fluids. Particles interact via a truncated Lennard-Jones pair potential in the absence of external fields. The effect of the surface area on the surface tension is investigated. It is found that the surface tension increases with the decrease of the surface area. However, this finite-size effect is pronounced only in small surface areas. In addition, our simulation results show that the finite-size correction of the surface tension is directly proportional to the reciprocal of the surface area, in accord with the prediction of the Gaussian model of capillary waves. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This study developed a fuzzy logic system for online variation detection by recognizing patterns in statistical process control (SPC) charts. The system enables quality engineers to take corrective actions for an out-of-control manufacturing process. The fuzzy logic SPC system has three subsystems and is able to detect most common four patterns. Data go through subsystems in the absence of detective patterns. Otherwise, data will be eliminated when a particular pattern is recognized on the SPC chart. The user-friendly output interface reduces human analysis errors. The performance of the developed fuzzy logic system is tested by a simulated process. [ABSTRACT FROM AUTHOR]

This paper introduces the concept of an advanced simulation-based design, “Feedback Loop Design”, and its realization method. The conventional simulation-based design was used for verification of the proposed design because the proposed design has a single process consisting of a design and the design verification. The feedback loop design involves a circular process consisting of the design, design verification, and design modification using an optimization design algorithm and multidisciplinary analysis tools. Optimized solutions can thereby be obtained through a circular design process. A software integration framework, which can combine various design algorithms and analysis tools as well as their interface methods is needed to realize the feedback loop design system. In this study, the software integration framework used is the Remote Component Environment (RCE) (DLR, Germany), and the analysis tool used is the commercial software, DAFUL & ANSYS, for verification of the developed concept. [ABSTRACT FROM AUTHOR]

Modern vehicles increasingly utilise a large display within the centre console, often with touchscreen capability, to enable access to a wide range of driving and non-driving-related functionality. The text provided on such displays can vary considerably in size, yet little is known about the effects of different text dimensions on how drivers visually sample the interface while driving and the potential implications for driving performance and user acceptance. A study is described in which sixteen people drove motorway routes in a medium-fidelity simulator and were asked to read text of varying sizes (9 mm, 8 mm, 6.5 mm, 5 mm, or 4 mm) from a central in-vehicle display. Pseudo-text was used as a stimulus to ensure that participants scanned the text in a consistent fashion that was unaffected by comprehension. There was no evidence of an effect of text size on the total time spent glancing at the display, but significant differences arose regarding how glances were distributed. Specifically, larger text sizes were associated with a high number of relatively short glances, whereas smaller text led to a smaller number of long glances. No differences were found in driving performance measures (speed, lateral lane position). Drivers overwhelmingly preferred the ‘compromise’ text sizes (6.5 mm and 8 mm). Results are discussed in relation to the development of large touchscreens within vehicles. [ABSTRACT FROM AUTHOR]

We report the simulation of current–voltage (I–V) and capacitance–voltage (C–V) characteristics of Au/n-InP Schottky contact in the temperature range of 200–400 K by steps of 20 K with and without interface states, traps and tunnelling current. The simulation was carried out using Atlas-Silvaco-Tcad device simulator. The simulation is performed using the appropriate physical models to explain the behaviour of the physical phenomena of the Schottky diode. The simulation results ofI–V–TandC–V–Twithout native oxide, tunnelling current and traps are far away from experimental data. Thus, native oxide, tunnelling current and traps should be considered. Our results strongly suggest that the spatial inhomogeneities at the MS interface did not affect theI–VandC–Vcharacteristics in the simulated temperature range. In addition, the extracted parameters, zero-bias barrier height, capacitance barrier heightand the ideality factorwere found to be strongly temperature-dependent due to the deviation of the transport mechanism from thermionic emission current. Moreover, the obtained results lead to a coherent explanation of the discrepancy betweenand. Good agreement of simulatedI–V–TandC–V–Tresults with existing experimental data are obtained by considering a thin native oxide layer at the interface, traps and tunnelling current. [ABSTRACT FROM PUBLISHER]

Ferroelectric switching in thin films is a local process strongly influenced by the presence and spatial distribution of defects such as dislocations, grain boundaries and preexisting domains. Preexisting ferroelastic domains have been shown to inhibit 180° switching in (001)-oriented epitaxial Pb(Zr 0.2 ,Ti 0.8 )O 3 (PZT) films, but ferroelectric switching pathways around these domains remain unclear. Here, phase field modeling with supporting high resolution transmission electron microscopy is used to investigate ferroelectric switching in PZT thin films around such a ferroelastic domain. We show 180° domain wall motion is arrested at moderate applied biases by the ferroelastic domain through formation of charged 90° domain walls during switching. This leads to an increased applied bias required for complete switching through the thin film. Charged 90° ferroelastic domain walls are found to be partially stabilized by local rotation of the polarization direction and significant broadening of the head-to-head wall to distribute the bound charge, leading to domain walls 5–6 nm in thickness compared to 0.5–2 nm for typical 90° domain walls. Ferroelectric switching continues only at higher applied electric fields. This study provides a more complete picture of the ferroelectric switching pathway around ferroelastic domains than has been previously available and may explain the experimentally observed lower stability of written domain structures around preexisting ferroelastic domain structures in epitaxial ferroelectric thin films. [ABSTRACT FROM AUTHOR]

Impurity atoms segregated in grain boundary (GB) regions can dramatically change the physical and chemical properties of the GBs. Such changes often appear to be attributed to the GB energy reduction and/or solute drag effect. Phase-field models have been utilized to clarify both the thermodynamic and kinetic effects of the GB segregation. In this study, we developed phase-field models for GB segregation that are diffuse interface versions of the classical two-phase model of GB segregation. The thermodynamic state at any point in the system is represented as a mixture of a GB phase and a matrix phase. There are two choices for the thermodynamic relation between the GB phase and the matrix phase that constitute the point: the equal composition condition in model I and the equal diffusion potential condition in model II. Most of the previous PFMs for GB segregation appear to be specific cases of model I. We examined the thermodynamic properties of models I and II, and compared them with each other and the classical two-phase model. Although all the models resulted in the same GB composition, the GB energy and its dependency on the composition at the equilibrium state are quite different from each other. In model I, there is a lower bound to the GB energy, which originates from the equal composition condition. The GB energy from model II shows no such lower bound, and it is represented as the vertical distance between the parallel tangent lines on the free energy diagram, as in the classical two-phase model. Nevertheless, the compositional dependence in the model II is quite different from that in the classical two-phase model. This originates from the different choices for the composition-independent parameter in the models: a constant gradient energy coefficient in model II and a constant GB width in the classical two-phase model. Model I is not suitable for simulations of alloys that show a reduction of the GB energy due to GB segregation below a certain limit (in dilute alloys, about half of the GB energy of pure solvents). Model II is a correct choice for such alloys. [ABSTRACT FROM AUTHOR]

Grain boundaries are the interfaces between differently oriented crystals of the same material. The underlying structures of grain boundary play a significant role in mechanical properties of polycrystalline materials. This influence becomes more significant when the grain size is reduced to ultrafine or nano size scale where the dislocation activities in the interior of grains lessen and mechanisms mediated by the grain boundary become dominant. This paper reviewed recent results in the atomistic simulation of the nanoscale behavior of grain boundary in face-centered cubic (fcc) metals. Three different simulation models were introduced to investigate the grain boundary behavior during plastic deformation, including three-dimensional (3D) nanocrystalline model, columnar nanocrystalline model and bicrystal model. The grain boundary was found to contribute to plastic deformation through the process of dislocation absorption, transmission or nucleation at boundary plane, as well as grain boundary accommodation mechanisms such as GB sliding and GB migration. These grain boundary mediated mechanisms were widely studied by the previous atomistic simulation works and were extensively reviewed here. Future challenges and directions in the computational study of grain boundary behaviors were also discussed. [ABSTRACT FROM AUTHOR]

Damage and failure process of the unidirectional fiber-reinforced ceramic matrix composites (FRCMCs) under tensile stress had been studied by many researchers in theoretical method. But because of some assumptions made in the theoretical model, it canot describe the performance of interface accurately. In this paper, evolving compliant interface (ECI) is employed to describe the properties of weak bonding interface. The ECI can respond the failure of debonding and sliding of interface efficiently. The whole damage evolution process of the material has been simulated by finite element method (FEM) and the stress-strain curve, the space of cracks at saturated state and the stress of components are discussed. The stress-strain curves of several ceramic composites were predicted by the model and compared with the experimental data. The results indicate that the tensile stress-strain curves agree well with the experimental data on consideration of Evolving compliant interfacial debonding model. [ABSTRACT FROM AUTHOR]

In this work, an example of practical implementation of the auxiliary sub-circuit (ASC) for modeling of the NBTI effects in DG FinFETs is described. A good agreement between the simulated and measured electrical characteristics of p-type DG FinFETs fabricated in SOI technology has been obtained using the industry-standard BSIM-CMG model with ASC. The oxide and interface trap densities are extracted in Spice simulations by tuning the ASC trapped charge parameters to fit the NBTI experimental data. The increase of oxide and interface trapped charge in p-type DG FinFET device is found to follow the logarithmic dependence with NBTI stress time. [ABSTRACT FROM AUTHOR]

A method is presented to quantify the radiated power from a high-density connector. This method is based on network parameters and the principle of conservation of power. Unlike previous work, which assumed only radiated losses were present, the proposed method is able to characterize the radiated power in environments that contain material losses and when there are multiple signals at the printed circuit board/connector interface. The power losses are quantified through the definition of power loss constant matrices that can be used to find the power losses for arbitrary input excitations when the matrices are entirely known. The power loss constant matrices can be calculated through multiple single-port and two-port excitations for an N-port connector. The formulation of these excitations is dictated by the nonlinear properties of the power loss calculation. Simulations and measurements are presented that validate the proposed power loss calculation methodology. [ABSTRACT FROM AUTHOR]

Atmospheric pressure interfaces were a fundamental structure for transferring air generated ions into the vacuum manifold of a mass spectrometer. This work is devoted to the characterization of ion transfer in metal capillaries through both experimental and simulated investigations. The impact of capillary configurations on ion transmission efficiency was evaluated using an electrospray mass spectrometer with various bent capillaries as the transfer devices. In addition, a numerical model has been set up by coupling the SIMION 8.0 and the computational flow dynamics for simulation study of ion migration in the complex atmospheric system. The transfer efficiency was found to be highly affected by the variation in electric field and the capillary geometry, revealing that the hydrodynamic and electric force were both dominant and interactional during the transmission process. The consistency of the results from the experimental analysis and simulation modeling proved the validity of the model, which was helpful for understanding ion activity in transfer capillaries. [ABSTRACT FROM AUTHOR]

This paper presents a numerical method to simulate the particle trajectory in the head–disk interface (HDI). The simulator solves the reduced Navier–Stokes equation with the second-slip boundary conditions to get the air velocity distribution, then solves the motion equations of particles and obtains the trajectories of the particles in the HDI using the binary Lagrange interpolation and the fourth-order Runge–Kutta method. The calculated trajectories of particles follow well with the air streamlines in the recessed regions. The particle density, diameter, and initial entering velocity have different effects on particle movement. Furthermore, particle velocity behaviors in the recessed regions are investigated for the first time. The particle is accelerated or decelerated by the action of the drag force and becomes close to the velocity of local air flow. Such effects are more obvious for small particles than large particles. The particle velocity becomes very small when it is close to the leading edge of the trailing pad. The numerical results also show that the particle goes up when it crosses the transition regions, and the particle moves upward more sharply with higher initial entrance height due to the larger vertical velocity of the local air flow. [ABSTRACT FROM AUTHOR]

In this paper, a doubly periodic interfacial cracking problem in a layered periodic composite is analyzed under antiplane shear loads. To further understand the interaction effect among the periodic interfacial cracks, four crack configurations are considered, namely a bilayered composite containing a single crack and a periodic array of collinear cracks, a layered periodic composite with a periodic array of parallel cracks and a doubly periodic rectangular array of cracks. In view of the periodic symmetry, the three periodic problems are transformed to a mixed boundary value problem for a single crack problem in an appropriate cell with the suitable periodic boundary conditions on its boundaries. The treatment skills for the periodic array of collinear cracks and the disposal techniques for the periodic array of parallel cracks are used together to solve the doubly periodic rectangular array of cracking problem. To demonstrate the computational accuracy of the present method, detailed comparative analyses are carried out. Numerical results are presented to show the interaction effect among the periodic interfacial cracks. For the doubly periodic rectangular array of cracking problem, parametric studies on the stress intensity factors leads out the following rule: the shielding effect of multiple parallel cracks and the amplifying effect of multiple collinear cracks exist simultaneously, and a coupled effect between geometrical and physical parameters on the interfacial fracture behavior exists clearly. [ABSTRACT FROM AUTHOR]

The ultra-high density of bimetal interfaces in nanolayered metal composites is responsible for exceptional five- to ten-fold increases in strength over that of the constituent phases. How interfaces cause such outstanding results is not fully understood. On the one hand, interfaces fundamentally alter the physical mechanisms responsible for plastic deformation—an important facet of the problem that has been intensely studied. On the other hand, plastic deformation also results in the creation of new interfaces. While this second facet holds equal importance, it has received comparatively less attention. Further, these two facets, coined interface-driven plasticity and plasticity-driven interfaces, are naturally coupled processes during deformation. The time and length scales characteristic of mesoscale characterization and simulation methods make them well suited for understanding their connection. Along these lines, here we focus on the use of mesoscale characterization and modeling to explore the role that bimetal interfaces play in their own self-development during severe plastic deformation. We demonstrate how mesoscale modeling can provide valuable insight into the design of materials processing techniques with stable interfaces in mind. [ABSTRACT FROM AUTHOR]

Introducing lattice mismatch-induced tensile strain at hetero-interfaces may be an efficient approach to enhance ionic conductivity at moderate temperatures. Extensive theoretical and experimental research has focused on strain- versus -ionic conductivity correlations. However, the correlation between strain and ionic conductivity still lacks a systematic and quantitative investigation. In this report, we derive an analytical expression to evaluate quantitatively the strain-induced enhancement in ionic conductivity. We demonstrate that simulation and experimental data in the literature, are well explained in the framework of our derived expressions. Our studies provide a powerful platform for quantitatively designing and engineering heterostructure interfaces for a number of applications, including fuel cells/batteries and optical/magnetic devices. [ABSTRACT FROM AUTHOR]

Power hardware-in-the-loop simulation (PHILS) has been introduced to its rapid prototyping and accurate testing under various load and interface conditions for power electronics applications. Real-time simulation with advancements in computing technologies can effectively support the PHILS to improve the computation speed of complex target systems converted to electrical and mathematical models. In this paper, advancements of optimized model constructions for a single crystalline photovoltaic (PV) panel are built up for the PHILS with a real-time simulator in the view points of improving dynamic model accuracy and boosting the computation speed. The dynamic model accuracy is one of significant performance factors of the PHILS which should show the dynamic performance of the simulation model during elaborate emulations of the power hardware. In addition, several considerations for the PHILS system such as system configuration and communication are provided to electrically emulate the PV panel with power hardware interfaces. The effectiveness of the proposed PHILS developed on Opal RT's RT-Lab real-time engineering simulator based on Matlab/Simulink is experimentally verified using a prototype PHILS system. [ABSTRACT FROM AUTHOR]

The focus of this work is to investigate spall fracture in polycrystalline materials under high-speed impact loading by using an atomistic-based interfacial zone model. We illustrate that for polycrystalline materials, increases in the potential energy ratio between grain boundaries and grains could cause a fracture transition from intergranular to transgranular mode. We also found out that the spall strength increases when there is a fracture transition from intergranular to transgranular. In addition, analysis of grain size, crystal lattice orientation and impact speed reveals that the spall strength increases as grain size or impact speed increases. [ABSTRACT FROM AUTHOR]

We report the first simulations of the Faraday instability using the full three-dimensional Navier-Stokes equations in domains much larger than the characteristic wavelength of the pattern. We use a massively parallel code based on a hybrid front-tracking/level-set algorithm for Lagrangian tracking of arbitrarily deformable phase interfaces. Simulations performed in square and cylindrical domains yield complex patterns. In particular, a superlattice-like pattern similar to those of Douady & Fauve (Europhys. Lett., vol. 6, 1988, pp. 221-226) and Douady (J. Fluid Mech. vol. 221, 1990, pp. 383-409) is observed. The pattern consists of the superposition of two square superlattices. We conjecture that such patterns are widespread if the square container is large compared with the critical wavelength. In the cylinder, pentagonal cells near the outer wall allow a square-wave pattern to be accommodated in the centre. [ABSTRACT FROM AUTHOR]

Results of a high resolution Detached Eddy Simulation (DES) are used to characterize the evolution of a shallow mixing layer developing between two parallel streams in a long open channel with a smooth flat bed and medium size dunes. The study discusses the vertical non-uniformity in the mixing layer structure and provides a quantitative characterization of the growth of the large-scale quasi two-dimensional (2D) coherent structures with the distance from the splitter plate. Results show that in streamwise sections situated between 75 D ( D is the channel depth) and 150 D from the splitter plate, the width of the mixing layer close to the free surface is 20–30% more than the width in the near-bed region. This is mostly because of the tilting of the mixing layer interface on the low-speed side toward the low speed stream as the free surface is approached. Power spectra of the horizontal velocity components near the free surface show the presence of a −3 subrange, corresponding to inverse energy cascade in two-dimensional turbulence, at streamwise locations situated more than 10 D from the splitter plate, consistent with the presence of large-scale quasi 2D horizontal eddies and the transfer of energy (inverse energy cascade) from the smaller scales toward these eddies. Consistent with visualizations of the mass transport of a passive scalar within the mixing layer, close to the free surface, the estimated streamwise length of the quasi 2D mixing layer eddies is about 2.5–3.0 times larger than the local width of the mixing layer. The presence of large-scale roughness elements in the form of an array of two-dimensional dunes with a maximum height of 0.25 D ( D is the channel depth) induces a much more rapid and larger shift of the centerline of the mixing layer due to the increased influence of the bottom roughness. [ABSTRACT FROM AUTHOR]

A finite element approach for calculating the energy release rate ( G ) and individual modes ( G I and G II ) when simulating crack growth through a two-dimensional composite material is presented. A new mesh-substitution scheme is used with basic fracture mechanics concepts to automatically calculate G , G I , and G II for potential growth along material interfaces and at different kink angles. The method is general and can be used when investigating interface cracks, substrate cracks (i.e., cracks contained in a material region), and substrate cracks with tips touching one or more interfaces. For bimaterial interface cracks, a coupled energy release rate ( G I–II ) is determined, and complex stress intensity factor components are calculated. A complete crack propagation framework, which includes the developed methods, is presented and then used to simulate crack growth through a composite material. [ABSTRACT FROM AUTHOR]

We performed phase-field simulations to analyse the interaction of a migrating grain boundary with an evolving second-phase particle. It is found that depending on the difference between the interfacial energies of the particle–matrix interface for the two grain orientations involved and the driving force for grain boundary movement, particles with a particle size well above the critical limit can dissolve due to passage of the boundary. [ABSTRACT FROM AUTHOR]

A Mesh Superposition Technique (MST) for the progressive transition between differently-discretized subdomains is proposed and implemented in an FE code. The interfaces between these subdomains are replaced by transition regions where the corresponding meshes are superposed. The MST is applied to the multiple length/time-scale analysis of a low-velocity impact of a projectile on a composite plate. Unlike using a sudden discretization-transition approach, the use of the MST eliminates the undesirable stress disturbances at the interface between differently-discretized subdomains and, as a result, it correctly captures the impact-induced damage pattern at a lower computational cost. Finally, the MST is coupled with an implicit/explicit co-simulation technique for a multiple time/length-scale analysis. The results indicate that, if the length-scale transition is performed using the proposed MST instead of a sudden discretization-transition, the CPU time can be nearly halved. [ABSTRACT FROM AUTHOR]

This paper focuses on the development of a 3D/1D patched transient heat transfer model (called 3D/1D patched model). It is proposed for getting accurate thermal boundary conditions in investment castings. In the 3D/1D model, heat transfer in the mould is assumed to take place only in a direction perpendicular to the mould, called 1D heat transfer and is computed via the FD solution of a 1D heat transfer equation. To reduce computational cost and simplify the mesh generation, the coordinates of cell centre and the temperature in the mould can be calculated by the model instead of meshing mould. When 1D patched model is integrated into the 3D CFD code PHYSICA, An area is present where 3D/1D model cannot cover, called ‘dead corner’. To overcome the effect of ‘dead corner’, a patch is introduced to put on it. The simulation results show that the 3D/1D patched model improves the accuracy when calculating the heat transfer through the mould–casting interface. However, it does not function well in 3D geometrical model. [ABSTRACT FROM AUTHOR]

Fingering instability triggered by injection of a less viscous fluid in a Hele-Shaw cell is numerically investigated. Simulations are based on a diffuse-interface method, and the formulation, capable of dealing with immiscible and miscible interfaces, is presented in details. Three miscibility conditions, including immiscible with surface tension, partially miscible with effective interfacial tension and fully miscible without interfacial stresses, are simulated to verify generality of an optimal linear injection scheme proposed by Dias et al. (Phys Rev Lett 109:144502, ) in the limit of infinite viscosity contrast. stabilizing effects of this linear injection scheme are universally confirmed for the interfaces with the presence of interfacial stresses, such as immiscible and partially miscible conditions. On the other hand, the linear injection scheme in a fully miscible interface leads to contradictory results. Even the fingering pattern appears qualitatively more stable without the secondary phenomenon of finger merging, relevant quantitative measurements, such as longer channeling zone and interfacial length, indicate enhancement of fingering prominence. The inconsistent behaviors suggest that the coupling effects with the interfacial stresses are crucial in the applications of the optimal linear injection scheme. [ABSTRACT FROM AUTHOR]

Thispaper presents a simulation study of vacuum membrane distillation(VMD) for desalination. A simulation model was built on the AspenPlus platform as a user defined unit operation for the VMD module.A simplified mathematical model was verified, and the analysis ofprocess performance based on simulation was also carried out. Temperatureand concentration polarization effects are significant in the conditionsof higher feed temperature and/or vacuum pressure. The sign of (PI,f– PI,p), difference of the vapor pressures between the membranes at theinterfaces, is an indicator of the vacuum pressure threshold. Increasingthe vacuum pressure at lower feed temperature is an effective wayto increase the permeate flux and reduce the energy consumption simultaneously. [ABSTRACT FROM AUTHOR]

Sea-salt aerosol global models are typically evaluated against concentration observations at coastal stations that are unaffected by local surf conditions and thus considered representative of open ocean conditions. Despite recent improvements in sea-salt source functions, studies still show significant model errors in specific regions. Using a multiscale model, we investigated the effect of high model resolution (0.1° × 0.1° vs. 1° × 1.4°) upon sea-salt patterns in four stations from the University of Miami Network: Baring Head, Chatam Island, and Invercargill in New Zealand, and Marion Island in the sub-antarctic Indian Ocean. Normalized biases improved from +63.7% to +3.3% and correlation increased from 0.52 to 0.84. The representation of sea/land interfaces, mesoscale circulations, and precipitation with the higher resolution model played a major role in the simulation of annual concentration trends. Our results recommend caution when comparing or constraining global models using surface concentration observations from coastal stations. [ABSTRACT FROM AUTHOR]