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Breakdown (BD) voltage is significant in high-voltage power electric machines. Currently, BD voltages are mainly predicted by the semi-empirical formula in strongly inhomogeneous electric fields. However, the equation could not be applied for electrodes with weakly inhomogeneous electric fields. In this paper, positive lightning impulse BD voltages are predicted in various sphere-to-plane air gaps using forms of machine learning such as support vector regression (SVR), Bayesian regression (BR) and multilayer perceptron (MLP). Unlike previous studies, a method is also proposed by introducing streamer propagation characteristics as new features and by removing electric field gradients as unnecessary features to find out how to reduce the feature dimension. The streamer propagation characteristics are suggested to reflect the possibility of a discharge process between electrodes. Predicted voltages from machine learning algorithms are compared with the experimental results and calculated voltages from the semi-empirical formula. Firstly, the predictions from each model agreed well with the datasets. New features were observed to be applied for machine learning algorithms and to be as important as known electrostatic features before discharge. Secondly, predicted BD voltages were more accurate than calculated voltages from the semi-empirical equation in strongly inhomogeneous electric fields. Predictions from each model also agreed well with the experimental results in weakly inhomogeneous electric fields. The prediction accuracy of SVR was better than those of BR and MLP. Machine learning algorithms were also shown to be applied for electrodes with a wide range of inhomogeneities, unlike a semi-empirical method. We expect that the suggested features and machine learning algorithms can be used for accurately calculating BD voltages. [ABSTRACT FROM AUTHOR]

The field of quantum resource theory (QRT) has emerged as an invaluable framework for the examination of small and strongly correlated quantum systems, surpassing the boundaries imposed by traditional statistical treatments. The fundamental objective of general QRTs is to characterize these systems by precisely quantifying the level of control attainable to an experimenter. In this review article, we refrain from providing an exhaustive summary of the extensive literature on QRT. Rather, our focus centers on a specific subliterature founded upon the theory of majorization. The primary aim is to augment our comprehension of genuine quantum phenomena manifested across diverse technological applications and incite investigations into novel resource theories encompassing multiple types of resources. Consequently, we emphasize the underlying similarities shared by various resources, including bipartite quantum entanglement, quantum coherence, and superposition, alongside informational, thermal, and generalized nonequilibrium resources. [ABSTRACT FROM AUTHOR]

In the work using the finite element method, a three-dimensional computer model of the processes of electrothermal treatment of an aluminium core of a power cable in an electric furnace and a thermostat was developed, and the patterns of changes in the temperature field in such a core were determined under different modes of implementation of the so-called "annealing" processes, that is, the restoration of the necessary electrical properties in it , in particular, an increase in specific electrical conductivity and plasticity. Calculations based on the developed mathematical model and the obtained regularities are consistent with the results of practical measurements of electrical conductivity and plasticity of experimental samples of aluminium cores of cables manufactured by YUZHCABLE WORKS, PJSC, Kharkiv. However, the analysis of the patterns of changes in the temperature field in the volume of aluminium cores of cables during their continuous electric heating to the required temperatures of both the outer and inner layers of the core wound on a spool showed that the difference in their temperatures can exceed 50 0С. Such nonuniformity of the temperature field of the core and long-term overheating of its outer layers leads to unacceptable losses of electricity and reduces the positive result of the processes of such heat treatment of the core, in particular, regarding the increase of its electrical conductivity. It is substantiated that in order to reduce the loss of electricity and the nonuniformity of the temperature field in the aluminium core, it is necessary to reduce the duration of electric heating of the aluminium core to the temperature of its upper layers, necessary for annealing, and then move the drum with such a core to a thermostat without electronic heating elements. In such a thermostat, the temperature of the outer layers will decrease, and the temperature of the inner layers will continue to increase. The work shows that after some time (≈ 60 min), the temperature distribution in the core will become almost uniform, and the total losses of electricity and the nonuniformity of the temperature field in the volume of the core will become smaller. Based on the results of the calculations, recommendations were developed for the selection of appropriate modes of heat treatment of aluminium cores wound on a spool, with acceptable energy consumption and overheating of the upper layers of the core.

HPR1000 NPP is designed with Passive Containment Heat Removal System (PCS) following the technical route called active and passive combined concept. The installed PCS system will have effect on the thermal hydraulic (T-H) behavior in the containment, and the complex T-H environment will influence the heat removal and operating character of PCS system backwards. The main goal of this work is to evaluate the effectiveness of the PCS system of HPR1000 and analyse the complex T-H environment of HPR1000 when the PCS system is operating. The HPR1000 containment is modelled by the containment T-H code and the PCS system is modelled based on experiment results. Then, the severe accident sequence initiated by large break LOCA is calculated by an integrated computer code, which outputs mass and energy release sources from reactor coolant primary system as boundaries for the containment T-H code. The results show that HPR1000 PCS system has enough heat removal capability under selected severe accident, which could ensure the containment meet the design requirement. Also, the nonuniformity of temperature and gases in the containment will disappear when the mass and energy releases turn stable, and the operating of PCS system does not cause a huge effect on containment inhomogeneity.

The nonuniformity of stress and strain analysis is an important consideration that describes the bond behavior between concrete and externally bonded fiber reinforced polymer (FRP) laminates. The interfacial stress transfer between FRP and concrete generates a longitudinal strain gradient in the longitudinal (or FRP fiber) direction. Most of the available studies in this area have focused on nonuniformity in the longitudinal direction. In this paper, the nonuniformity in the FRP width direction is investigated by studying the strain distribution using digital image correlation (DIC) full-field optical techniques. In the direction along the FRP width, there is an area in the middle that has consistent strain and stress, while the edge regions have strain and stress gradients. During the complete debonding process, the width of the central area is found to be insignificantly affected by the concrete strength but significantly affected by the FRP stiffness. The fracture characteristics below the central region are purely Mode II fracture. However, the complex curved cracks and high in-plane shear strains at the interface near the FRP edge regions show a mixed mode with Modes II and III. This boundary effect results in a significant difference in the bond–slip characteristics of FRP along the width direction. The maximum bond stress of the central region is higher than that of the edge region. However, for FRP with higher stiffness, the inhomogeneity of the stress distribution is weakened. Moreover, it is reasonable to find that calculating the sum of the bearing capacity of the single FRP strips along the width direction is close to the experimental bond strength. Based on the research findings in this study, it is qualitatively recommended that the width factor model in calculating FRP-concrete bond strength should include the significant effect of FRP stiffness. • The stress and deformation nonuniformities in the FRP width direction are initially investigated. • The width of the central stable portion increases with increasing FRP stiffness but is insensitive to the concrete strength. • By dividing the FRP into multiple strips with different bond–slip curves, the sum load matches well with the experimental peak load. • A new rational and accurate width factor model considering the FRP stiffness effect is necessary to be developed. [ABSTRACT FROM AUTHOR]

Photo response nonuniformity (PRNU) is a crucial parameter in evaluating and choosing CMOS image sensors. The current methods and standards use the integrating sphere to illuminate the sensor and assume a known uniform illumination. And PRNU is calculated based on the spatial variance of images. In practice, the uniformity of illuminance can be hardly guaranteed. A slight nonuniformity will cause a significant increase in spatial variance and bring unacceptable evaluation errors. In this article, we present a novel method to estimate PRNU of linear CMOS image sensors. The method allows nonuniform illumination and does not require specific settings for the light source and sensors. First, an observation model is established for the data of nonuniformly exposed images. The model is composed of an irradiance model and a noise model. The irradiance model describes the original output, and the noise model depicts the noise variance as a function of local illuminance. PRNU is a parameter in the noise model to be estimated. Then, the model parameters including PRNU are estimated by a two-stage method based on maximum likelihood estimation. We also use simulations to validate the developed methods and demonstrate the robustness of the model under sensor misalignment. Finally, the proposed method is illustrated by a measurement experiment. [ABSTRACT FROM AUTHOR]

Featured Application: The work uses a patch-based inpainting method that is capable of filling the missing areas or removing unwanted objects in a digital image. Patch-based image inpainting methods iteratively fill the missing region via searching the best sample patch from the source region. However, most of the existing approaches basically use the fixed size of patch regardless of content features nearby, which may lead to inpainting defects. Also, global match is needed for searching the best sample patch, but only to fill one target patch in each iteration, resulting in low efficiency. To handle the issues above, we first evaluate the nonuniformity in an image, by which the patch size is adaptively determined. Moreover, we divide the source region into multiple non-overlapping subregions with different nonuniformity levels, and the patch match proceeds in every subregion, respectively. This strategy not only saves the match time for single target patch, but also reduces the mismatch, and enables the simultaneous filling of multiple target patches in a single iteration. Experimental results show that in comparison to previous patch-based works, our method has achieved further improvement both in quality and efficiency. We believe our method could provide a new way for patch match with better accuracy and efficiency in image inpainting tasks. [ABSTRACT FROM AUTHOR]

The results of kinematic analysis of the ASz-62IR radial engine crankshaft was presented. In addition, the one-dimensional model of the working cycle of the engine was created in AVL BOOST system. Differences in the waveforms for each pistons causes the differences in the filling process what reflects in the mass of the load supplied to cylinders. Additionally, due to one dimensional model computation. The results show differences in the value of maximum pressure. This causes differences in mean effective pressure of up to 4% and which also affects the vibrations of the whole engine.

Device dimension scaling and process complexity have revealed new phenomena such as post-breakdown (BD) and variability issues in advanced technology nodes. Coupling of the first BD phenomena and their methodologies discussed in part I with the development of post-BD methodologies allows engineers to use device stress-data to accurately predict the product failure lifetime. The statistical modeling and new advances in understanding the root cause of variability issues have mitigated these seemingly uncontrollable “catastrophes” so that the scaling of the advanced technology process can continue its successful path forward. These two important aspects of dielectric BD will be reviewed in part II. [ABSTRACT FROM AUTHOR]

For most large-area applications, spatial nonuniformity of transistor characteristics makes it difficult if not impossible, to achieve adequate performance. Nonuniform parameters may lead to variations in color or gray level, which is commercially not viable. A variation in threshold voltage, mobility or ${I}-{V}$ characteristics of an organic thin-film transistor (OTFT) in a pixel circuit can result in unacceptable variation in the current driving the organic light-emitting diode (OLED) which accounts for large nonuniformities in the pixel brightness. Given its importance, a fast and straightforward method for characterization of device variations would be of great help in the process development and optimization. In the present work, a simple, easy to fabricate two-terminal asymmetric metal–insulator–semiconductor (AMIS) capacitive test structure is proposed for quick and accurate characterization of the process-induced nonuniformities in mobility, threshold voltage, and drain current. The capacitance–voltage (${C}-{V}$) characteristic of the proposed AMIS structure is derived mostly from the channel, and its contribution to the total capacitance at any given frequency depends on channel properties including mobility and threshold voltage. At low frequencies, the ${C}-{V}$ characteristics become independent of the series resistances, and hence, complex techniques can be sidestepped for accurate estimation of channel properties. The simulation results are presented to demonstrate the concept using a single AMIS test structure. The experimental results obtained with top contact pentacene based on AMIS arrays are presented to show the concept and advantages of the proposed structure. [ABSTRACT FROM AUTHOR]

Evaluating the joint significance of covariates is of fundamental importance in a wide range of applications. To this end, p-values are frequently employed and produced by algorithms that are powered by classical large-sample asymptotic theory. It is well known that the conventional p-values in Gaussian linear model are valid even when the dimensionality is a non-vanishing fraction of the sample size, but can break down when the design matrix becomes singular in higher dimensions or when the error distribution deviates from Gaussianity. A natural question is when the conventional p-values in generalized linear models become invalid in diverging dimensions. We establish that such a breakdown can occur early in nonlinear models. Our theoretical characterizations are confirmed by simulation studies. [ABSTRACT FROM AUTHOR]

Patch-based image inpainting methods iteratively fill the missing region via searching the best sample patch from the source region. However, most of the existing approaches basically use the fixed size of patch regardless of content features nearby, which may lead to inpainting defects. Also, global match is needed for searching the best sample patch, but only to fill one target patch in each iteration, resulting in low efficiency. To handle the issues above, we first evaluate the nonuniformity in an image, by which the patch size is adaptively determined. Moreover, we divide the source region into multiple non-overlapping subregions with different nonuniformity levels, and the patch match proceeds in every subregion, respectively. This strategy not only saves the match time for single target patch, but also reduces the mismatch, and enables the simultaneous filling of multiple target patches in a single iteration. Experimental results show that in comparison to previous patch-based works, our method has achieved further improvement both in quality and efficiency. We believe our method could provide a new way for patch match with better accuracy and efficiency in image inpainting tasks.

Contact problem for a system of rigid rough punches and layered foundation with nonuniform upper layer is considered.Mathematical model of the problem is compiled. It's effective solution is constructed by using Manzhirov projection method. Qualitative conclusions are presented. [ABSTRACT FROM AUTHOR]

Mild steel was successfully joined by linear friction welding. Grain size at peripheral region was coarser than that at the other zones of the weld interface, which had no significant effect on microhardness. The local tensile properties were considerably decreased when oxides or lack of bonding appeared at the interface. Ductile fracture dominated the fracture mode for all joints. Variation in local tensile properties could be relieved under a medium friction pressure, a relatively high amplitude with a sufficient friction time. It was attributed to the facts that plastic metal layer of joint became uniform to some extent and interfacial defects were eliminated. The standard deviation of plastic metal layer thickness (χp) could be used to describe the combined effects of welding parameters on joint integral performance. It was found that the standard deviation of plastic metal layer thickness showed a strong inverse correlation with the joint integral performance. Well-formed and defect-free joints exhibiting 90% of the base metal tensile strength could be produced when processing at a frequency of 20 Hz with a friction pressure of 103 MPa or 155 MPa, an amplitude of 2.5 mm and a friction time of at least 4 s. [ABSTRACT FROM AUTHOR]

Ligaments serve as compliant connectors between hard tissues. In that role, they function under various load regimes and directions. The 3D structure of ligaments is considered to form as a uniform entity that changes due to function. The periodontal ligament (PDL) connects the tooth to the bone and sustains different types of loads in various directions. Using the PDL as a model, employing a fabricated motorized setup in a microCT, we demonstrate that the fibrous network structure within the PDL is not uniform, even before the tooth becomes functional. Utilizing morphological automated segmentation methods, directionality analysis, as well as second harmonic generation imaging, we find high correlation between blood vessel distribution and fiber density. We also show a structural feature in a form of a dense collar around the neck of the tooth as well as a preferred direction of the fibrous network. Finally, we show that the PDL develops as a nonuniform structure, with an architecture designed to sustain specific types of load in designated areas. Based on these findings, we propose that ligaments in general should be regarded as nonuniform entities, structured already at developmental stages for optimal functioning under variable load regimes. [ABSTRACT FROM AUTHOR]

A method of smoothing uneven dosing of microcomponents in continuous flows of granular materials by the action of a cascade of counter pulses on a segregated flow of the components is described. Mathematical modeling is used to analyze the physical mechanism of smoothing fluctuations of microcomponent dosage portions in a continuous granular materials mixer having a rotating drum. The influence of design and operating parameters of the apparatus on the magnitude of fluctuation of concentration of batch-dosed components in the mixture is studied using an experimental relationship that determines the intensity of formation of a segregated flow in a drum apparatus for a mixture of model granular materials. [ABSTRACT FROM AUTHOR]

As a critical parameter of the steady uniform friction model, the roughness coefficient changes with flow unsteadiness in flood events; i.e., the flow conditions of the stream segment significantly affect the flow resistance. In this study, a modified formula was established to improve the unsteady friction simulation; ten terms relating to the first- and second-order time and space partial derivatives of hydraulic parameters were selected as additional terms. The results of a hydraulic experiment show that the hysteresis between flow depth and mean cross-sectional velocity cannot be neglected in unsteady flows that disturb the performance of a steady uniform friction model. Six terms have a strong correlation with objective friction. Further, three of them have a small variance in correlation coefficient. Then, the composition of the proposed formula was determined. The results show that adding too many additional terms provides better performance in the calibration phase, yet reduces the accuracy of the validation phase because of an overfitting phenomenon. The optimal number of additional terms is three, and the established formula can improve the unsteady friction simulation. [ABSTRACT FROM AUTHOR]

As one of the important sources of low-frequency noise, random telegraph noise (RTN) in tunnel FET (TFET) has attracted growing attention recently. However, there is still lack of explanation for the high-amplitude RTN, which may cause serious variability and reliability problems to TFET-based ultralow-power circuits. In this paper, we experimentally investigate the RTN amplitude characteristics in TFETs, revealing the mechanism of high-amplitude RTN. It is found that the nonuniform distribution of band-to-band tunneling (BTBT) generation rate along device width direction is responsible for the high-amplitude RTN. Locations with relatively higher BTBT generation rate may act as critical paths dominating the device current. “Lucky” trap located at a critical path can induce the high-amplitude RTN. With device width shrinking, the number of critical paths may be reduced, resulting in much higher maximum RTN amplitude. In addition, the impacts of process parameters on RTN amplitude are discussed. Both higher source doping concentration ( \textN\text {S}) and higher thermal budget can effectively mitigate the nonuniformity of BTBT generation rate along device width direction, causing suppressed RTN amplitudes. Considering that the higher thermal budget may lead to degraded device performance, the annealing process should compromisingly be designed in terms of both variation and device performance. [ABSTRACT FROM PUBLISHER]

The brain is an organ that functions as a network of many elements connected in a nonuniform manner. In the brain, the neocortex is evolutionarily newest and is thought to be primarily responsible for the high intelligence of mammals. In the mature mammalian brain, all cortical regions are expected to have some degree of homology, but have some variations of local circuits to achieve specific functions performed by individual regions. However, few cellular-level studies have examined how the networks within different cortical regions differ. This study aimed to find rules for systematic changes of connectivity (microconnectomes) across 16 different cortical region groups. We also observed unknown trends in basic parameters in vitro such as firing rate and layer thickness across brain regions. Results revealed that the frontal group shows unique characteristics such as dense active neurons, thick cortex, and strong connections with deeper layers. This suggests the frontal side of the cortex is inherently capable of driving, even in isolation and that frontal nodes provide the driving force generating a global pattern of spontaneous synchronous activity, such as the default mode network. This finding provides a new hypothesis explaining why disruption in the frontal region causes a large impact on mental health., Competing Interests: The authors declare no competing financial interests., (Copyright © 2023 Matsuda et al.)

In our previous paper (Kanagawa et al., J. Fluid Sci. Tech., 5, 2010), we have proposed a systematic method for derivation of various types of nonlinear wave equations for plane waves in bubbly liquids. The method makes use of an asymptotic expansion with multiple scales in terms of a small wave amplitude as an expansion parameter and a set of scaling relations of physical parameters, based on basic equations of two-fluid model of bubbly flows. In this paper, we extend the method so as to handle a weakly diffracted ultrasound beam in a quiescent liquid containing a number of spherical gas bubbles distributed with a weak nonuniformity. Because of the high expandability of the original method, the extension can be accomplished by adding a scaling relation of the diameter of the beam to the original set of scaling relations. As a result, we derive a generalized Khokhlov—Zabolotskaya—Kuznetsov (KZK) equation [or a generalized Kadomtsev—Petviashvili (KP) equation] for a long wave and low frequency case.

Tube bundle heat exchangers have been recognized as the most efficient means of thermal exchange. The staggered row method can enhance the performance of a heat exchanger. However, it results in a large pressure drop loss. As working media with high thermal conductivities, liquid metals can potentially replace conventional working media. In this study, for working fluids with low Prandtl number cross flowing through a staggered tube bundle, the turbulent Prandtl number model of cross flow was verified. The unsteady characteristics of the two working fluids traversing through the tube bundle were analyzed. The effects of molecular thermal diffusion on the total heat transfer capacity of the two working fluids during heat transfer were compared, along with the changes in the circumferential heat transfer characteristics of the tube bundles under different Reynolds numbers. The ζ factor was then proposed to analyze the non-uniformity in the heat transfer characteristics of a single tube. An empirical correlation describing the heat transfer non-uniformity at the fully developed region and inlet region and involving parameters such as working properties and flow state was proposed based on computational fluid dynamics data. Finally, the performance evaluation criteria(PEC) factor was used to analyze the comprehensive performance of the two heat transfer fluids. The results revealed that the comprehensive heat transfer performance of mercury was 60–70 times that of conventional working fluids. [ABSTRACT FROM AUTHOR]

Relationship between exponential dichotomies and admissibility of function classes is a significant problem for hyperbolic dynamical systems. It was proved that a nonuniform exponential dichotomy implies several admissible pairs of function classes and conversely some admissible pairs were found to imply a nonuniform exponential dichotomy. In this paper we find an appropriate admissible pair of classes of Lyapunov bounded functions which is equivalent to the existence of nonuniform exponential dichotomy on half-lines R ± separately, on both half-lines R ± simultaneously, and on the whole line R . Additionally, the maximal admissibility is proved in the case on both half-lines R ± simultaneously. [ABSTRACT FROM AUTHOR]

Applicability problems of the widely-used aggregation-based representation of DFIG wind farms focus on the modelling “error and impact” in transient stability computation. In order to identify crucial LVRT behaviors of DFIGs, specifically in system-level analysis, control strategies including vector-orientation, closed-loop rotor-current regulation, and Crowbar protection are given a full consideration. It is proved that, the DFIG works with its electrical and mechanical dynamics decoupled, and the result is that the DFIG behaves as an ideal controlled-power source. The DFIG's power-modulation functions defined by the grid code distinguish it from the conventional synchronous generator, which also conveniently offers dominant dynamics for studying errors of aggregation. Next, errors caused by the coupling between distribution factors and LVRT behaviors of wind farms (but ignored in aggregation) are discussed. With some existing grid codes, these factors not only generate a distributive profile of residual voltages along the feeders, but more importantly nonuniform power responses among individual wind turbines. Impacts of aggregation's errors on transient stability of power systems are analyzed. The trend in the error and impact of aggregation is analytically surveyed in a rudimentary system, and further numerically verified in a multi-machine system. [ABSTRACT FROM PUBLISHER]

An electrostatic nonuniformity in the cantilever vertical tunneling FETs intrinsically exists in the InAs/GaSb junction to InAs cantilever transition region. The effects of the coupling ratio (CR) nonuniformity are investigated in this paper. The results show that the switching characteristics are degraded by the CR nonuniformity, especially in the case of large InAs/GaSb band offset. This paper also reveals that the nonuniformity in InAs/GaSb vertical tunneling FETs can be mitigated with the optimized band offset of heterojunction, scaling of oxide thickness, and acute angle etching profile. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new scene-based nonuniformity correction technique for infrared focal plane arrays. Our work is based on the use of two well-known scene-based methods, namely, adaptive and interframe registration-based exploiting pure translation motion model between frames. The two approaches have their benefits and drawbacks, which make them extremely effective in certain conditions and not adapted for others. Following on that, we developed a method robust to various conditions, which may slow or affect the correction process by elaborating a decision criterion that adapts the process to the most effective technique to ensure fast and reliable correction. In addition to that, problems such as bad pixels and ghosting artifacts are also dealt with to enhance the overall quality of the correction. The performance of the proposed technique is investigated and compared to the two state-of-the-art techniques cited above. [ABSTRACT FROM AUTHOR]

The tube-type transparent conducting oxide target is preferred to the planar type owing to a prolonged life. The uniaxial pressing of 2 wt% Al–ZnO powder into a tube shape and subsequent sintering resulted in a tapered product owing to the nonuniform green density. To suppress the taper, an initial heat treatment (IHT) under an external pressure was applied prior to the main final sintering. The degree of the taper was estimated from the difference in the percentage between the longer and shorter diameters of the tube. The application of pressure (1 MPa) during the IHT at 800 °C decreased the taper from 4.3% to 0.9% after pressureless final sintering at 1250 °C. The application of pressure during the IHT activated shrinkage at the bottom part of the tube and consequently reduced the tapering. With the IHT under pressure, micron-sized voids fragmented into the submicron pores, and the sintering potential was improved. [ABSTRACT FROM AUTHOR]

Natural soils in site are mainly unsaturated under evaporation or infiltration effects, which cause nonuniformity along depth or present nonlinearity in strength properties even for uniform soil strata. Conventional upper-bound analysis is unable to handle the above issues, requiring alternative approach such as the discretization-based kinematic analysis to be adopted. Nonlinear matric suction profile along depth is theoretically formulated under one-dimensional steady flow. Within the context of extended Mohr Coulomb (MC) failure criterion, total cohesion is explicitly expressed for unsaturated soils. Meanwhile, an extended Power-law failure criterion is proposed to consider nonlinear characteristics of uniform soils in unsaturated zones. Based on these two failure criteria, upper-bound analyses of unsaturated clay slopes' stability are evaluated by slope safety factor (FoS). Optimal upper-bound FoS solutions are sought by a strength reduction technique and iterative algorithm. Effects of clayey soils' non-uniformity, nonlinearity and some other influential factors on unsaturated slope stability are investigated, which is of engineering significance for sound design and reliable assessment of unsaturated slopes. One of key findings is that stability of unsaturated soil slopes enhanced by their unsaturated soil strength is substantial and should be utilized to derive a more economical design or construction of temporary slopes in practice. [ABSTRACT FROM AUTHOR]

The abrasive effect of particles is one of the basic mechanical actions in chemical mechanical polishing (CMP). In this paper, numerical simulations of particle sliding trajectories are performed to examine the influence of the kinematic parameters on the polishing uniformity of typical rotary-type CMP equipment. The trajectory simulations are carried out based on the kinematic analysis. The results reveal that the speed ratio \alpha and the period ratio kT0, which represent the coupling relationships among the three basic motions of CMP, are the two major factors affecting the trajectory distribution. Further, a trajectory density parameter is proposed to quantitatively evaluate the global uniformity of the trajectory distributions and to optimize the kinematic parameters for better uniformity. The statistical results of the trajectory density analysis reveal that the trajectory of the wafer edge is denser than that of the wafer central area. To obtain better trajectory uniformity, some particular values of \alpha and kT0, that is, \alpha=1 and kT0=1, which imply that the basic motions have a special coupling relationship, should be excluded; the preferred kinematic parameter values for CMP are \alpha=0.91\--0.93 and kT0=5\--7. This paper provides a basic guide to the kinematic parameter settings of CMP. [ABSTRACT FROM AUTHOR]

Consider a circle with perimeter N > 1 on which k < N segments of length 1 are sampled in an independent and identically distributed manner. In this paper we study the probability π(k, N) that these k segments do not overlap; the density φ(⋅) of the position of the disks on the circle is arbitrary (that is, it is not necessarily assumed uniform). Two scaling regimes are considered. In the first we set k ≡ α √N, and it turns out that the probability of interest converges (N → ∞) to an explicitly given positive constant that reflects the impact of the density φ(⋅). In the other regime k scales as αN, and the nonoverlap probability decays essentially exponentially; we give the associated decay rate as the solution to a variational problem. Several additional ramifications are presented. [ABSTRACT FROM AUTHOR]

In this paper, the kinematic analysis and numerical calculation are used to discuss the effect of the kinematic parameters on the final polishing result of typical rotary chemical-mechanical polishing (CMP) equipment. The relative velocity distribution and the sliding distance distribution are calculated based on the kinematic analysis. Especially, the coupling relationships between the kinematic parameters are investigated and discussed. And two parameters of the sliding distance nonuniformity (SDNU) and the sliding distance nonuniformity within concentric circles (SDNU\-cc) are proposed and calculated to evaluate the global uniformity of the sliding distance and to reveal the coupling relationships between the kinematic parameters. The results suggest that the relative velocity distribution and the sliding distance distribution are significantly affected by the coupling effects of the basic motions of CMP system; the SDNU is mainly affected by parameter \alpha, which represents the coupling relationship between the rotary motions of the wafer carrier and the polishing platen; the SDNU\-cc is mainly affected by parameter kT{0}^{\prime}(\alpha kT0), which represents the coupling relationship between the reciprocating motion and the rotary motion of the wafer carrier; \alpha\approx 1 and \alpha kT0>2 are proper for better polishing uniformity in real CMP process. [ABSTRACT FROM PUBLISHER]

Abstract: A three-dimensional and two-phase flow model to predict the dynamic behavior of a fluid catalytic cracking (FCC) industrial reactor was developed in this work. The study took into account heat transfer and chemical reactions. A four-lump model was proposed to represent the catalytic cracking reactions in which the heavy oil (gas oil) is converted into gasoline and light hydrocarbon gases. Gas acceleration inside the reactor due to molar expansion and a model to describe undesirable catalyst deactivation by coke deposition on its surface were also considered. An Eulerian description of the phases was used to represent the two-phase flow. A commercial CFD code (Ansys CFX version 11.0) was used to obtain the numerical data. Appropriate functions were implemented inside the CFX code to model the heterogeneous kinetics and catalyst deactivation. Results show nonuniform tendencies inside the reactor, emphasizing the importance of using three-dimensional models in FCC process predictions. [Copyright &y& Elsevier]

Mechanical stresses of magnetically induced origins are becoming more serious with the trend of high-temperature superconductor (HTS) heavy-current transformer (HCT) applications. Mechanical forces in HTS HCTs that act on the transformer windings are generated by the interaction between the current density and the leakage flux density. This paper presents the calculation of leakage flux and mechanical force distribution in high-current HTS transformer windings. This requires the need for advanced numerical techniques for simulation studies using finite-element method by adapting two auxiliary windings for the leakage flux mitigation and, thereby, mechanical forces within the main windings. A model is developed for the calculation of mechanical force considering nonuniformity of both field and current distributions in the windings, which is the main motivation for initiating this paper. [ABSTRACT FROM AUTHOR]

The simulation of remote-sensing images is a useful tool for a variety of tasks, such as the definition of future Earth Observation systems, the optimization of instrument specifications, and the development and validation of data processing algorithms. A scene simulator for optical hyperspectral and multispectrai data has been implemented in the frame of the Environmental Mapping and Analysis Program (EnMAP) mission. EnMAP is German-built hyperspectral space sensor scheduled for launch 2012. EnMAP will measure in the 420-2450-nm spectral range at a varying spectral sampling of 6.5-10 nm. Images will cover 30 x 30 km areas at an approximate ground sampling distance of 30 m. The EnMAP scene simulator presented in this paper able to generate realistic EnMAP-like data in an automatic way under a set of user-driven instrumental and scene parameters. Radiance and digital numbers data are generated by five sequential processing modules which are able to produce data over a range of natural environments, acquisition and illumination geometries, cloud covers, and instrument configurations. The latter include the simulation of data nonuniformity in the spatial and spectral domains, spatially coherent and noncoherent instrumental noise, and instrument's modulation transfer function. Realistic surface patterns for the simulated data are provided by existing remote-sensing data in different environments, from dry geological sites to green vegetation areas. A flexible radiative transfer simulation scheme enables the generation of different illumination, observation, and atmospheric conditions. The methodology applied to the complete scene simulation and some sample results are presented and analyzed in this paper. [ABSTRACT FROM AUTHOR]

To establish a 2D axisymmetric quasi–static finite element model during the chemical mechanical polishing process, revolutions of the wafer and the pad were assumed to be the same, the axisymmetric uniformly distributed pressure form was given, and both the wafer–pad interface and wafer–film interface were considered as contact boundaries. Next, the height of the contact interface between the carrier and the film near the zone of nonuniform von Mises stress distribution of the wafer surface was changed to the form of a Fourier sine series. Finally, a quadratic programming method was utilized to solve the coefficients of the Fourier sine series and then an optimal morphology in terms of Fourier sine series under the condition of minimum nonuniformity of the wafer surface was achieved. The result found that the nonuniformity was reduced remarkably and its improved rate reaches 88.45% under the optimal surface of the carrier. [ABSTRACT FROM AUTHOR]

In this study, a three-dimensional finite element model was established to perform modal analysis of the chemical mechanical polishing process. The contact boundary conditions were considered in the wafer and pad, and the influence of the static load exerted on the carrier was considered in order to investigate dynamic behaviour of the wafer. The analysis was in two steps. Firstly, a given pressure was exerted on the carrier and the geometric nonlinear effect and large deformation theory were used to carry out static analysis. Secondly, the results of the analysis were used to perform modal analysis of the wafer. The results gave way to four conclusions. (1) Due to the offset configuration of the wafer and pad, the von Mises stress distribution was asymmetric. Therefore, the stress on the wafer appeared to be almost uniform near its centre, goes through a maximum near the edge, and decreased as the edge is approached. This tendency is similar to that of the removal rate profile experiment, which proved that the proposed finite element model for CMP is acceptable. (2) Due to the extremely thin thickness of the film, wafer and pad, most mode shapes are predominant in out-plane deformation. Furthermore, since the y-axis is symmetric in the three-dimensional model, there were double roots in some modes. (3) When the load was larger, the tangent stiffness and the natural frequency would also be reduced. The pressure changes did not have much affect on mode shape. (4) Since the soft materials of the pad and film have significantly different Young’s modulus’ than hard materials, the natural frequencies of harder materials for the pad and film increase. [ABSTRACT FROM AUTHOR]

Abstract: The transient temperature response of a crossflow heat exchanger is carried out using finite difference method accounting for the effect of temperature and flow nonuniformity at different input conditions. Beta flow maldistribution model has been introduced for the flow nonuniformity. The responses are found dependent on the relative position of the individual temperature streams and the position of the fluid moving device for the temperature and flow nonuniformity, respectively. Combined effect of temperature and flow nonuniformity has also been analysed and compared with the other cases. [Copyright &y& Elsevier]

In this paper, we analyze the nonuniformity of sliding distance on both the wafer and polishing pad from a kinematic point of view. Using the Fourier series expansion, it can be shown that in steady state the nonuniformity caused by contact relative velocity is determined by rotational speed ratio between platen and wafer carrier (m) and the ratio of wafer radius to the distance between the platen center and wafer center (Rc/d). In general, the nonuniformity of wafer increases with ml and (Rc/d). An important observation for the polishing pad is that in two particular ranges of the ratio m, larger (Rc/d) on the contrary yields smaller nonuniformity. Then, a ring-type polishing pad is proposed for the purpose of improving the nonuniformity of both wafer and pad. However, it turns out the result for the pad of large size is worse than the traditional shape, unless the rotational speed of the pad is much slower than that of the wafer. [ABSTRACT FROM AUTHOR]

During the chemical mechanical polishing process (i.e., CMP for short), it is expected to attain the requirement of global planarization. However, the stress concentration, which occurred when approaching the wafer edge, has resulted in over-grinding. The increasing material removal rate has also contributed to the wafer’s nonuniformity. In this paper, a retaining ring surrounding the wafer carrier was added to the conventional CMP mechanism in order to improve the over-grinding phenomenon and avoid the wafer sliding from the carrier as much as possible. The revolutions of the wafer and the pad were assumed to be the same, and the force forms of the carrier and the retaining ring were axisymmetric uniformly-distributed. In addition, when the principle of minimum potential energy was applied, a two-dimensional axisymmetric quasi-static finite element model for CMP including the carrier, the retaining ring, the film, the wafer and the pad could be established. Following this model, the von Mises stress distribution of the wafer surface without a retaining ring was analyzed to verify the model. The effects of the gap between the ring and the pad and the ratio of the ring load and the carrier load on the stress and the wafer’s nonuniformity were investigated. The results indicated that the von Mises stress distribution of the wafer surface was almost uniform near the wafer center, and the maximum value appeared near the edge. The value decreased as the edge was approached, but it rose again very close to the edge. Besides, the wafer’s nonuniformity would be prohibited while the gap and the load were designed within the certain range to supply the retaining ring. [ABSTRACT FROM AUTHOR]

The energy absorption capability is a key parameter for ZnO varistors. This paper discusses the nonuniformity of energy absorption capabilities of ZnO varistors. With experiment results, we show that energy absorption capabilities of ZnO varistors can be highly scattered, for different commercial varistors, and for the same varistors under diverse current waves. We explain this nonuniformity phenomenon through numerical simulations, based on the microscopic circuit and heat transfer models of ZnO varistors. How the applied current, the nonuniformity of microstructure, and the nonuniformity of microstructural electrical and thermophysical characteristics influence the energy absorption capabilities of ZnO varistors is also analyzed. [ABSTRACT FROM AUTHOR]

A nonclassical model of shells that accounts for transverse shears and reduction is used to develop a method for solving the contact problem for inhomogeneous anisotropic shells of revolution subject to a field of mechanical and thermal loads. The prestresses are described by parametric terms in the linearized geometrically nonlinear equations of the second-order theory of flexible shells. The influence of the prestressed state of shells interacting with a flat surface on the contact area and the distribution of contact pressure is analyzed. Some computational features of the technique are discussed [ABSTRACT FROM AUTHOR]

In order to investigate AC current distributions in high Tc superconducting (HTS) coils, we have developed a measurement method to evaluate the current distributions in a HTS solenoidal coil. In this method, the current distributions are indirectly found from the results of the field distributions measured by pickup coils located around the sample coil surface. To confirm the accuracy and sensitivity of this method, current distributions in a test coil made of insulated copper wires are measured. Numerical and measured field distributions are compared, and it is found that our method is accurate enough to measure the current distributions for the HTS coils. Using this method, we measured the current distributions in a Bi-2223 solenoidal coil at room temperature and 77 K. The comparison between the experimental and numerical results shows that the current distributions in the HTS coil are not uniform. On the basis of the obtained results, the characteristics of the AC current distributions in the HTS coils are discussed. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, modeling of a two-dimensional axisymmetric quasic-static finite element model in conjunction with an abductive network for chemical–mechanical polishing process (CMP) was established. Three prediction models can be achieved, i.e., model for von Mises stress at wafer center, model for maximum von Mises stress and model for nonuniformity on wafer surface under various combinations of process parameters. The data of von Mises stress and nonuniformity on wafer surface can be first achieved under different conditions of the carrier load, pad''s elastic modulus and thickness by using the developed finite element model for CMP. Next, an abductive network was applied to synthesize the data sets from the FE simulation. It is a self-organizing adaptive modeling tool that establishes the mathematical relationship between input and output variables based on abductive modeling technique and it can automatically synthesize the optimal network structure, including the optimal network structure, the number of layers and the form of functional nodes. Finally, the results from the three developed abductive networks with test data are compared with those from FE simulation to confirm the feasibility of this approach. The findings verified that the results confirm the feasibility and the proposed prediction models for CMP are acceptable. [Copyright &y& Elsevier]

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The nonuniformity of electrical characteristics of grain boundaries in ZnO varistors was systematically analyzed. The high nonuniformity exists in barrier voltages and nonlinearity coefficients in different grain boundaries. The barrier voltages have normal distributions, only a few grain boundaries were electrically active, and the grain boundaries can be simply classified into good, bad, and ohmic ones according to the electrical characteristics of grain boundaries. The average barrier voltage is equal to 3.3 V by the direct method, but it is only 2.3 V by the indirect method. There is a high difference between the barrier voltages by direct and indirect measurement methods. These few good grain boundaries are responsible for the good varistor effect, and control the leakage current of ZnO varistor at low values of applied voltage. The Al[SUB2]O[SUB3] dopants affect the electrical characteristics of grain boundaries by changing the electron status in grain boundary and intragrain. [ABSTRACT FROM AUTHOR]

In this paper, a two-dimensional axisymmetric quasic-static model for the chemical-mechanical polishing process (CMP) was established. Based on the principle of minimum total potential energy, a finite element model for CMP was thus established. In this model, the four-layer structures including the wafer carrier, the carrier film, the wafer and the pad are involved. The von Mises stress distributions on the wafer surface were analysed, and the effects of characteristics of the pad and the carrier film and the load of the carrier on the von Mises stress and nonuniformity on the wafer surface were investigated. The findings indicate that the profile of the von Mises stress distributions correlates with the removal rate profile. The elastic modulus and thickness of pad and carrier load would significantly affect the von Mises stress and nonuniformity, but those of the film did not affect very much. [ABSTRACT FROM AUTHOR]