The calculation of liquid-vapor phase equilibrium in H<Subscript>2</Subscript>O-H<Subscript>2</Subscript>O<Subscript>2</Subscript> two-component system

The dependences of total pressure and equilibrium composition of vapors on temperature and mole fraction of hydroperoxide in solution are calculated for a water-hydroperoxide two-component two-phase system. It is assumed that the relaxation to concentration equilibrium in gas at the surface of solution is attained quite rapidly compared to the half-life of hydroperoxide. Three independent approximate methods are used to calculate the total pressure. The ideal gas approximation for the gas phase is not used in two of these methods. Approximation formulas are suggested, which explicitly express the dependence of pressure and composition of gas on relative concentration of hydroperoxide in solution and on temperature. The accuracy of the methods and the range of their validity are discussed.     

Solution of generalized density evolution equation via a family of <Emphasis Type="Italic">δ</Emphasis> sequences

The traditional probability density evolution equations of stochastic systems are usually in high dimensions. It is very hard to obtain the solutions. Recently the development of a family of generalized density evolution equation (GDEE) provides a new possibility of tackling nonlinear stochastic systems. In the present paper, a numerical method different from the finite difference method is developed for the solution of the GDEE. In the proposed method, the formal solution is firstly obtained through the method of characteristics. Then the solution is approximated by introducing the asymptotic sequences of the Dirac δ function combined with the smart selection of representative point sets in the random parameters space. The implementation procedure of the proposed method is elaborated. Some details of the computation including the selection of the parameters are discussed. The rationality and effectiveness of the proposed method is verified by some examples. Some features of the numerical results are observed.     

Low-temperature liquid-phase epitaxy growth from Ga–As–Bi solution

Measurements of Ga–As–Bi liquidus composition at 600 °C for Ga–Bi–GaAs range are reported. High quality GaAs layers and Al_0.28Ga_0.72As/GaAs single quantum well (SQW) structures with different well thicknesses are grown from a mixed Ga + Bi solvent by low-temperature liquid-phase epitaxy method. They are characterized by the Hall effect and photoluminescence (PL) measurements. Significant changes in the layer electrical properties are observed with varying the Bi content in the solution. The layers grown from a mixed solution with 20–30% Bi content are n-type with carrier concentration of 10¹⁴ cm^− 3 and mobility of 40 000 cm²/Vs at 77 K, while p-type high resistivity layers are obtained from a solution with more than 70% Bi content. PL spectra of the SQW structures grown from Ga + 25% Bi solution at 2 K show that the roughness at the interface is less than two monolayers.     

Modal‐based goal‐oriented error assessment for timeline‐dependent quantities in transient dynamics

This article presents a new approach to assess the error in specific quantities of interest in the framework of linear elastodynamics. In particular, a new type of quantities of interest (referred as timeline‐dependent quantities) is proposed. These quantities are scalar time‐dependent outputs of the transient solution, which are better suited to time‐dependent problems than the standard scalar ones, frozen in time. The proposed methodology furnishes error estimates for both the standard scalar and the new timeline‐dependent quantities of interest. The key ingredient is the modal‐based approximation of the associated adjoint problems, which allows efficiently computing and storing the adjoint solution. The approximated adjoint solution is readily post‐processed to produce an enhanced solution, requiring only one spatial post‐process for each vibration mode and using the time‐harmonic hypothesis to recover the time dependence. Thus, the proposed goal‐oriented error estimate consists in injecting this enhanced adjoint solution into the residual of the direct problem. The resulting estimate is very well suited for transient dynamic simulations because the enhanced adjoint solution is computed before starting the forward time integration of the direct problem. Thus, the cost of the error estimate at each time step is very low. Copyright © 2013 John Wiley & Sons, Ltd.     

Semi‐analytic solution for multiple interacting three‐dimensional inhomogeneous inclusions of arbitrary shape in an infinite space

This paper develops a semi‐analytic solution for multiple arbitrarily shaped three‐dimensional inhomogeneous inclusions embedded in an infinite isotropic matrix under external load. All interactions between the inhomogeneous inclusions are taken into account in this solution. The inhomogeneous inclusions are discretized into small cuboidal elements, each of which is treated as a cuboidal inclusion with initial eigenstrain plus unknown equivalent eigenstrain according to the Equivalent Inclusion Method. All the unknown equivalent eigenstrains are determined by solving a set of simultaneous constitutive equations established for each equivalent cuboidal inclusion. The final solution is obtained by summing up the closed‐form solutions for each individual equivalent cuboidal inclusion in an infinite space. The solution evaluation is performed by application of the fast Fourier transform algorithm, which greatly increases the computational efficiency. Finally, the solution is validated by taking Eshelby's analytic solution of an ellipsoidal inhomogeneous inclusion as a benchmark and by the finite element analysis. A few sample results are also given to demonstrate the generality of the solution. The solution may have potentially significant applications in solving a wide range of inhomogeneity‐related problems. Copyright © 2011 John Wiley & Sons, Ltd.     

Unraveling the Solution‐State Supramolecular Structures of Donor–Acceptor Polymers and their Influence on Solid‐State Morphology and Charge‐Transport Properties

Polymer self‐assembly in solution prior to film fabrication makes solution‐state structures critical for their solid‐state packing and optoelectronic properties. However, unraveling the solution‐state supramolecular structures is challenging, not to mention establishing a clear relationship between the solution‐state structure and the charge‐transport properties in field‐effect transistors. Here, for the first time, it is revealed that the thin‐film morphology of a conjugated polymer inherits the features of its solution‐state supramolecular structures. A “solution‐state supramolecular structure control” strategy is proposed to increase the electron mobility of a benzodifurandione‐based oligo(p‐ phenylene vinylene) (BDOPV)‐based polymer. It is shown that the solution‐state structures of the BDOPV‐based conjugated polymer can be tuned such that it forms a 1D rod‐like structure in good solvent and a 2D lamellar structure in poor solvent. By tuning the solution‐state structure, films with high crystallinity and good interdomain connectivity are obtained. The electron mobility significantly increases from the original value of 1.8 to 3.2 cm² V^?1 s^?1. This work demonstrates that “solution‐state supramolecular structure” control is critical for understanding and optimization of the thin‐film morphology and charge‐transport properties of conjugated polymers.     

Solution‐Processing of High‐Purity Semiconducting Single‐Walled Carbon Nanotubes for Electronics Devices

High‐purity semiconducting single‐walled carbon nanotubes (s‐SWCNTs) are of paramount significance for the construction of next‐generation electronics. Until now, a number of elaborate sorting and purification techniques for s‐SWCNTs have been developed, among which solution‐based sorting methods show unique merits in the scale production, high purity, and large‐area film formation. Here, the recent progress in the solution processing of s‐SWCNTs and their application in electronic devices is systematically reviewed. First, the solution‐based sorting and purification of s‐SWCNTs are described, and particular attention is paid to the recent advance in the conjugated polymer‐based sorting strategy. Subsequently, the solution‐based deposition and morphology control of a s‐SWCNT thin film on a surface are introduced, which focus on the strategies for network formation and alignment of SWCNTs. Then, the recent advances in electronic devices based on s‐SWCNTs are reviewed with emphasis on nanoscale s‐SWCNTs' high‐performance integrated circuits and s‐SWCNT‐based thin‐film transistors (TFT) array and circuits. Lastly, the existing challenges and development trends for the s‐SWCNTs and electronic devices are briefly discussed. The aim is to provide some useful information and inspiration for the sorting and purification of s‐SWCNTs, as well as the construction of electronic devices with s‐SWCNTs.     

Insight into the flow‐condition‐based interpolation finite element approach: solution of steady‐state advection–diffusion problems

The flow‐condition‐based interpolation (FCBI) finite element approach is studied in the solution of advection–diffusion problems. Two FCBI procedures are developed and tested with the original FCBI method: in the first scheme, a general solution of the advection–diffusion equation is embedded into the interpolation, and in the second scheme, the link‐cutting bubbles approach is used in the interpolation. In both procedures, as in the original FCBI method, no artificial parameters are included to reach stability for high Péclet number flows. The procedures have been implemented for two‐dimensional analysis and the results of some test problems are presented. These results indicate good stability and accuracy characteristics and the potential of the FCBI solution approach. Copyright © 2005 John Wiley & Sons, Ltd.     

Time‐parallel implicit integrators for the near‐real‐time prediction of linear structural dynamic responses

The time‐parallel framework for constructing parallel implicit time‐integration algorithms (PITA) is revisited in the specific context of linear structural dynamics and near‐real‐time computing. The concepts of decomposing the time‐domain in time‐slices whose boundaries define a coarse time‐grid, generating iteratively seed values of the solution on this coarse time‐grid, and using them to time‐advance the solution in each time‐slice with embarrassingly parallel time‐integrations are maintained. However, the Newton‐based corrections of the seed values, which so far have been computed in PITA and related approaches on the coarse time‐grid, are eliminated to avoid artificial resonance and numerical instability. Instead, the jumps of the solution on the coarse time‐grid are addressed by a projector which makes their propagation on the fine time‐grid computationally feasible while avoiding artificial resonance and numerical instability. The new PITA framework is demonstrated for a complex structural dynamics problem from the aircraft industry. Its potential for near‐real‐time computing is also highlighted with the solution of a relatively small‐scale problem on a Linux cluster system. Copyright © 2006 John Wiley & Sons, Ltd.     

Crystal Growth and Structure of the Zn<Subscript>0.97</Subscript>Cd<Subscript>0.03</Subscript>As<Subscript>2</Subscript> Solid Solution

Single crystals of the Zn_0.97Cd_0.03As₂ solid solution are prepared, and their structure is determined by x-ray diffraction. The incorporation of Cd into ZnAs₂ has no effect on its lattice parameters (to within the error of determination). Cd is shown to occupy interstitial sites in the solid solution.     

A modified electrochemical procedure for isolating <Superscript>177</Superscript>Lu radionuclide

A cell for isolating ¹⁷⁷Lu from a neutron-irradiated ¹⁷⁶Yb target was developed. The procedure involves a combination of two processes: contact reduction of Yb from acetate–chloride solution on sodium amalgam, followed by electrolysis of the solution on a mercury cathode. The process conditions were chosen so that the adjustment of the working solution characteristics (composition, pH, etc.) in going from contact reduction to electrolysis was not required. Both processes are performed in one cell, which reduces the ¹⁷⁷Lu loss. On an installation consisting of two cells, the decontamination factor of the ¹⁷⁷Lu solution from Yb of up to 10⁶ was reached, which is necessary for obtaining a ¹⁷⁷Lu preparation of high specific activity.     

Bubble‐enhanced smoothed finite element formulation: a variational multi‐scale approach for volume‐constrained problems in two‐dimensional linear elasticity

This paper presents a bubble‐enhanced smoothed finite element formulation for the analysis of volume‐constrained problems in two‐dimensional linear elasticity. The new formulation is derived based on the variational multi‐scale approach in which unequal order displacement‐pressure pairs are used for the mixed finite element approximation and hierarchical bubble function is selected for the fine‐scale displacement approximation. An area‐weighted averaging scheme is employed for the two‐scale smoothed strain calculation under the framework of edge‐based smoothed FEM. The smoothed fine‐scale solution is shown to naturally contain the stress field jump of the smoothed coarse‐scale solution across the boundary of edge‐based smoothing domain and thus provides the possibility to stabilize the global solution for volume‐constrained problems. A global monolithic solution strategy is employed, and the fine‐scale solution is solved without the consideration of approximating the strong form of the fine‐scale equation. Several numerical examples are analyzed to demonstrate the accuracy of the present formulation. Copyright © 2014 John Wiley & Sons, Ltd.     

A <Emphasis Type="Italic">p-i-n</Emphasis> Model of CdTe/CdS Heterostructures

CdTe/CdS heterostructures are analyzed in terms of a p-i-n model in which the i layer consists of a CdTe_{1 − x} S_x solid solution resulting from Te and S diffusion into CdS and CdTe, respectively. The lattice parameters of the solid solution are determined. The i layer is shown to be too thick for tunneling.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 8, 2005, pp. 915–917.Original Russian Text Copyright © 2005 by Janabergenov, Mirsagatov, Karazhanov.     

Efficient Removal of Polyvalent Metal Impurities from KH<Subscript>2</Subscript>PO<Subscript>4</Subscript> by Crystallization

The separation factors of metal impurities for potassium dihydrogen phosphate crystallization from nonstoichiometric solutions have been experimentally determined. Based on the results obtained, a method has been proposed that makes it possible to obtain a material containing aluminum, iron, chromium, and titanium at a level of ~5 × 10^–2 ppm by weight from commercially available raw materials. In this method, a KH₂PO₄ solution is purified due to partial crystallization of the macrocomponent, so that the above impurities are concentrated in the solid phase. The purified solution is then boiled down with KOH additions.     

Zur exakten und näherungsweisen Berechnung unidirektionalverstärkter Kunststoffe

Exact and Approximate Calculations of UD-Layers It is shown that the quasi-elastic solution of layers nearly almost used in practical viscoelastic calculations is an excellent approach. The exact solution achieved with simple integral equations are compared with the quasi-elastic solution and the occuring deviations are described. The creep functions of layers are given the form of the uniaxial creep function of the isotropic viscoelastic material. This makes the creep behaviour of layers very clear and symplifies practical calculations. The given solutions are under no restriction with regard to the chosen form of the uni-axial creep function.     

Bifurcation analysis of nonlinear time‐periodic time‐delay systems via semidiscretization

Bifurcations of the periodic stationary solutions of nonlinear time‐periodic time‐delay dynamical systems are analyzed. The solution operator of the governing nonlinear delay‐differential equation is approximated by a sequence of nonlinear maps via semidiscretization. The subsequent nonlinear maps are combined to a single resultant nonlinear map that describes the evolution over the time period. Fold, flip, and Neimark‐Sacker bifurcations related to the fixed point of this map are analyzed via center manifold reduction and normal form theorems. The analysis unfolds the approximate stability properties and bifurcations of the stationary solution of the delay‐differential equation and, at the same time, allows the approximate computation of the arising period‐1, period‐2, and quasi‐periodic solution branches. The method is demonstrated for the delayed Mathieu‐Duffing equation, and the results are verified by numerical continuation.     

The ‘effective-stress-function’ algorithm for thermo-elasto-plasticity and creep

An algorithm for stable and accurate computations of stresses in finite element thermo-elastic-plastic and creep analysis of metals is presented. The effective-stress-function algorithm solves the governing equations of the inelastic constitutive behaviour by calculating the zero of the appropriate effective-stress-function: a functional relationship which involves as unknown only the effective stress. The derivation of the effective-stress-function for thermo-elasto-plasticity conditions, including creep, for 2-D and 3-D analysis is presented, and the algorithmic steps of the stress solution are discussed. For use in the stiffness matrix a tangent material stress–strain relationship is evaluated consistent with the effective-stress-function algorithm. The solution of some demonstrative problems shows the effectiveness of the solution procedure.     

Conductivity of the nanostructured ceramic material Zr<Subscript>0.88</Subscript>Sc<Subscript>0.1</Subscript>Ce<Subscript>0.01</Subscript>Y<Subscript>0.01</Subscript>O<Subscript>1.955</Subscript> prepared from mechanically activated powders

The structure of the Zr_0.88 Sc_0.1Ce_0.01Y_0.01O_1.955 solid solution, a candidate for the use as a solid electrolyte in fuel cells with a low temperature, has been investigated using x-ray powder diffraction and Raman spectroscopy. Single-phase ceramic materials have been produced from powders prepared by the mechanochemical synthesis from ZrO₂ nanoprecursors purified of the impurities introduced during grinding of commercial zirconia. The solid solution has a rhombohedral structure at room temperature owing to the partial ordering of oxygen vacancies. The electrical conductivity of the ceramic materials sintered at temperatures below 1570 K exhibits a hysteresis due to the delay of the martensitic transition from the cubic phase to the rhombohedral phase upon cooling of the sample. The nanostructured ceramic materials are characterized by a high mechanical strength and unusually close values of the activation energies for bulk and grain-boundary electrical conduction.     

Analysis of three‐dimensional fracture mechanics problems: A two‐scale approach using coarse‐generalized FEM meshes

This paper presents a generalized finite element method (GFEM) based on the solution of interdependent global (structural) and local (crack)‐scale problems. The local problems focus on the resolution of fine‐scale features of the solution in the vicinity of three‐dimensional cracks, while the global problem addresses the macro‐scale structural behavior. The local solutions are embedded into the solution space for the global problem using the partition of unity method. The local problems are accurately solved using an hp‐GFEM and thus the proposed method does not rely on analytical solutions. The proposed methodology enables accurate modeling of three‐dimensional cracks on meshes with elements that are orders of magnitude larger than the process zone along crack fronts. The boundary conditions for the local problems are provided by the coarse global mesh solution and can be of Dirichlet, Neumann or Cauchy type. The effect of the type of local boundary conditions on the performance of the proposed GFEM is analyzed. Several three‐dimensional fracture mechanics problems aimed at investigating the accuracy of the method and its computational performance, both in terms of problem size and CPU time, are presented. Copyright © 2009 John Wiley & Sons, Ltd.     

Study of poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide) microparticles based on supercritical CO<Subscript>2</Subscript>

Poly(l-lactide) (PLLA) microparticles were prepared in supercritical anti-solvent process. The effects of several key factors on surface morphology, and particle size and particle size distribution were investigated. These factors included initial drops size, saturation ratio of PLLA solution, pressure, temperature, concentration of the organic solution, the flow rate of the solution and molecular weight of PLLA. The results indicated that the saturation ratio of PLLA solution, concentration of the organic solution and flow rate of the solution played important roles on the properties of products. Various microparticles with the mean particle size ranging from 0.64 to 6.64 μm, could be prepared by adjusting the operational parameters. Fine microparticles were obtained in a process namely solution-enhanced dispersion by supercritical fluids (SEDS) process with dichloromethane/acetone mixture as solution.