Differences in microstructure of Pd77.5Au6Si16.5 alloy solidified under microgravity and gravity conditions

The microstructure of Pd_77.5Au₆Si_16.5alloy solidified both on board a Chinese Retrievable Satellite and on the earth is studied. Postmortem analyses of microstructure presented that the same types of phases, primary phase (Pd₃Si) and eutectics (Pd₃Si + Pd solid solution) were formed in both cases. But the phase morphologies were quite different. It was dendritic for the primary phase and lamellar for the eutectics under normal gravity condition. However, under microgravity condition the primary phase was granular and the eutectic was peculiar network. Detailed analysis showed that the differences in morphologies of the microstructure were due to the existence of gravity-induced buoyancy convection on the earth which increased the mass transport abilities and decreased the thickness of the solute boundary in front of the solid-liquid interface during solidification under normal gravity condition.     

Structure and crystallization of bulk amorphous Pd41Ni10Cu28P21 alloy

Bulk amorphous Pd41Ni10Cu28P21 alloy has been prepared by water quenching method. The system shows excellent glass forming ability (GFA) with a high value of reduced glass transition temperature Trg, 0.714. Structural analyses indicate that the Pd41Ni10Cu28P21 alloy has a dense packing structure closer to "frozen liquid" than that of amorphous Pd40Ni40P20 alloy. Experiments on crystallization reveal that several crystalline phases simultaneously precipitate in the early part of crystallization. Below 710 K, a metastable phase forms, and subsequently disappears at elevated temperatures. In addition, the influence of partial substitute of Cu for Ni on GFA has been discussed with regard to thermodynamics and kinetics.     

Liquid structure of undercooled Cu70Ni30 alloy

Experiments of X-ray diffraction for liquid Cu70Ni30 alloy above and below its liquidus (1 230℃) have been carried out. By the analysis of experimental results, it is discovered that difference between structures of liquid and undercooled Cu70Ni30 alloy is their cluster sizes. The correlation radius of cluster is 1.125 nm and the atom number of cluster is 403 at 1 250_1 400℃, and they are 1.3 nm and 704 respectively at the undercooled liquid state (1 200℃). The structure of liquid Cu70Ni30 alloy is fcc short order and its solid structure, fcc, is kept from liquid fcc short order.     

Structure condition under initial enlargement of filtration

We address the question of how the structure condition is affected when one possesses some additional information at the very beginning of the investment period.The structure condition represents essentially an alternative to non-arbitrage conditions for the Markowitz’s portfolio optimization framework,and is crucial for the existence of the optimal portfolio in quadratic utility settings.Herein,we provide practical assumption on the initial market model and the additional information to preserve the structure condition.The stochastic tools that drive this result are a generalization of the Lazaro-Yor representation by Lazaro and Yor(1978)and optional stochastic integral.     

Directional differentiability of optimal solutions under Slater's condition

For convex parametric optimization problems it is shown that the optimal solution is directionally differentiable provided that a strong second-order sufficient optimality condition and Slater's condition are satisfied for the unperturbed problem. This directional derivative is equal to the optimal solution of a certain quadratic programming problem. For the construction of this quadratic problem, a preliminary choice of a suitable KKT-multiplier is necessary, which under additional assumptions may be taken as a vertex of the set of KKT-multipliers of the unperturbed problem. In the last part of this paper, the contingent derivative of the optimal solution is investigated.     

Lp solutions of reflected BSDEs under monotonicity condition

We prove existence and uniqueness of ${\mathbb{L}}^p$ solutions, $p\in [1,2]$, of reflected backward stochastic differential equations with $p$-integrable data and generators satisfying the monotonicity condition. We also show that the solution may be approximated by the penalization method. Our results are new even in the classical case $p=2$.     

Convergence of iterations of Euler family under weak condition

The iteration maps of Euler family for finding zeros of an operatorf in Banach spaces is defined as the partial sum of Taylor expansion of the local inversef _z ^-1 off atz. The unified convergence theorem is established for the iterations of Euler family under the assumption that , while the strong condition thatf is analytic in Smale’s criterion α is replaced by the weak condition thatf is of finite order derivative.     

独立约束条件下线性模型的参数估计

对线性回归的未知参数估计问题,在某些种假设的条件下已有结论,对有约束条件的情况下,线性回归模型中参数估计如何,本文给出了带有独立的约束条件下线性回归模型中参数β的最小二乘估计。     

Approximation of fourier integral by Bochner-Riesz means under one-side condition

In this paper we study the approximation of Fourier integral by Bochner-Riesz means under one-side condition and improve the results in[1].     

Local convergence of Newton’s method under majorant condition

A local convergence analysis of Newton’s method for solving nonlinear equations, under a majorant condition, is presented in this paper. Without assuming convexity of the derivative of the majorant function, which relaxes the Lipschitz condition on the operator under consideration, convergence, the biggest range for uniqueness of the solution, the optimal convergence radius and results on the convergence rate are established. Besides, two special cases of the general theory are presented as applications.     

Convergence behaviour of inexact Newton methods under weak Lipschitz condition

Under weak Lipschitz condition, local convergence properties of inexact Newton methods and Newton-like methods for systems of nonlinear equations are established in an arbitrary vector norm. Processes with modified relative residual control are considered; the results easily provide an estimate of convergence ball for inexact methods. For a special case, the results are affine invariant. Some applications are given.     

Analytic solutions of an iterative differential equation under Brjuno condition

In this paper, the differential equation involving iterates of the unknown function,
x＇（z）=[a^2-x^2（z）]x^[m]（z）
with a complex parameter a, is investigated in the complex field C for the existence of analytic solutions. First of all, we discuss the existence and the continuous dependence on the parameter a of analytic solution for the above equation, by making use of Banach fixed point theorem. Then, as well as in many previous works, we reduce the equation with the SchrSder transformation x（z） = y（αy^-1（z）） to the following another functional differential equation without iteration of the unknown function
αy＇（αz）=[a^2-y^2（αz）]y＇（z）y（α^mz）,
which is called an auxiliary equation. By constructing local invertible analytic solutions of the auxiliary equation, analytic solutions of the form y（αy^-1 （z）） for the original iterative differential equation are obtained. We discuss not only these α given in SchrSder transformation in the hyperbolic case 0 〈 ｜α｜ 〈 1 and resonance, i.e., at a root of the unity, but also those α near resonance （i.e., near a root of the unity） under Brjuno condition. Finally, we introduce explicit analytic solutions for the original iterative differential equation by means of a recurrent formula, and give some particular solutions in the form of power functions when a = 0.     

Local convergence analysis of inexact Newton-like methods under majorant condition

We present a local convergence analysis of inexact Newton-like methods for solving nonlinear equations under majorant conditions. This analysis provides an estimate of the convergence radius and a clear relationship between the majorant function, which relaxes the Lipschitz continuity of the derivative, and the nonlinear operator under consideration. It also allow us to obtain some important special cases.     

Persistence of lower-dimensional tori under the first Melnikov's non-resonance condition

In this paper we prove the persistence of lower-dimensional invariant tori of integrable equations after Hamiltonian perturbations under the first Melnikov's non-resonance condition. The proof is based on an improved KAM machinery which works for the angle variable dependent normal form. By an example, we also show the necessity of the Melnikov's first non-resonance condition for the persistence of lower dimensional tori.