All-optical clock recovery using a ridge width varied two-section partly gain-coupled DFB self-pulsation laser

A 1.55 μm InGaAsP-InP partly gain-coupled two-section DFB self-pulsation laser (SPL) with a varied ridge width has been fabricated. The laser produces self-pulsations with a frequency tuning range of more than 135 GHz. All-optical clock recovery from 40 Gb/s degraded data streams has been demonstrated. Successful lockings of the device at frequencies of 30 GHz, 40 GHz, 50 GHz, and 60 GHz to a 10 GHz sidemode injection are also conducted, which demonstrates the capability of the device for all-optical clock recovery at different frequencies. This flexibility of the device is highly desired for practical uses.     

双线性非协调有限元逼近的梯度恢复后验误差估计

给出了二阶椭圆方程的双线性非协调有限元逼近的梯度恢复后验误差估计.该误差估计是在Q_1非协调元上得到的,并给出了误差的上下界.进一步证明该误差估计在拟一致网格上是渐进精确地.证明依赖于clement插值和Helmholtz分解,数值结果验证了理论的正确性.     

Polynomial preserving recovery for meshes from Delaunay triangulation or with high aspect ratio

A newly developed polynomial preserving gradient recovery technique is further studied. The results are twofold. First, error bounds for the recovered gradient are established on the Delaunay type mesh when the major part of the triangulation is made of near parallelogram triangle pairs with ε‐perturbation. It is found that the recovered gradient improves the leading term of the error by a factor ε. Secondly, the analysis is performed for a highly anisotropic mesh where the aspect ratio of element sides is unbounded. When the mesh is adapted to the solution that has significant changes in one direction but very little, if any, in another direction, the recovered gradient can be superconvergent. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008     

On specific stability bounds for linear multiresolution schemes based on piecewise polynomial Lagrange interpolation

The Deslauriers-Dubuc symmetric interpolation process can be considered as an interpolatory prediction scheme within Harten's framework. In this paper we express the Deslauriers-Dubuc prediction operator as a combination of either second order or first order differences. Through a detailed analysis of certain contractivity properties, we arrive to specific l_∞-stability bounds for the multiresolution transform. A variety of tests indicate that these l_∞ bounds are closer to numerical estimates than those obtained with other approaches.     

一类具有逐段常变量神经网络系统概周期解存在性与指数稳定性

利用Halanay不等式,我们得到了一类具有逐段常变量神经网络系统解全局指数稳定的一个充分条件;此外,在同样条件下,通过不动点定理,证明了这类概周期系统概周期解的存在唯一性与模包含关系．     

Splitting as an approach to constructing local exact artificial boundary conditions

We employ the technique of splitting for constructing artificial boundary conditions (ABCs) for the linear advection–diffusion–reaction equation when the computational domain is an nD open set with a piecewise smooth artificial boundary. The splitting is performed both by the physical processes and by coordinates. The former permits to construct ABCs for each of the processes separately, which provides local exact boundary conditions; the latter leads to ABCs much less exigent to the shape of artificial boundary in comparison with many others. We also prove that the corresponding boundary value problems are well-posed, and present results of the numerical experiments that confirm the theoretical study.     

A simple elemental continuity based model application to study the anaerobic microbial activity for the treatment of dairy manure

A simple anaerobic digestion (AD) model was formulated with emphasis on understanding the microbial activity during AD. The model was formulated according to two main rules that regulate the microbial growth. The first rule was maintaining the elemental continuity of macronutrients C, H, N, O, P, and S. The second rule satisfied the thermodynamics of the main AD catabolic reactions: acidogenesis and both acetotrophic and hydrogenotrophic methanogenesis. Accordingly, the stoichiometric parameters were evaluated as functions of the bacterial yield. The model also considered the enzymatic hydrolysis of solid waste. For a known solid waste composition, experimental data was utilized to estimate microbial initial concentrations, yields and kinetics, i.e., to achieve better understanding of the main AD microbial activity. The model was applied to three sets of batch experiments focusing on anaerobic dairy manure degradation. The model predicted the degradation dynamics, estimated the bacterial concentration in different inoculums, and evaluated the effect of inoculum ratios in speeding up the degradation. Elemental continuity based formulation of the model evaluated additional components that are necessary for future studies of macronutrients recovery, limitation/toxic effects, and chemical equilibrium.     

基于时变耦合映像格子模型的信号初值估计

从耦合映像格子中,恢复系统初始条件是耦合系统求逆问题,也是信号处理研究中的一个关键性问题.本文在符号动力学方法的基础上,对映像系数进行修正,针对耦合单峰Logistic映射,提出一种基于时变映像系数恢复信号初值的新方法.在映像过程无噪或受到高斯白噪声污染时,本文方法都能够较好地恢复信号初值的统计特性,而且具有较小的偏差和均方误差,并与原信号之间具有较强的相关性,从而能够更好和更加合理地刻画实际信号的物理过程,对系统初值做出更优的估计. 关键词： 耦合映像格子 恢复初值的统计特性 时变映像系数     

Pseudo Almost Periodic Solutions of a Singularly Perturbed Differential Equation with Piecewise Constant Argument

Under suitable assumptions, the existence and the uniqueness of the pseudo-almost periodic solution for a singularly perturbed differential equation with piecewise constant argument are obtained. In addition, the stability properties of these solutions are characterized by the construction of manifolds of initial data.     

Applications of high energy ion beam techniques in environmental science: Investigation associated with glass and ceramic waste forms

High energy ion beam capabilities including Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) have been very effectively used in environmental science to investigate the ion-exchange mechanisms in glass waste forms and the effects of irradiation in glass and ceramic waste forms in the past. In this study, RBS and NRA along with SIMNRA simulations were used to monitor the Na depletion and D and ¹⁸O uptake in alumina silicate glasses, respectively, after the glass coupons were exposed to aqueous solution. These results show that the formation of a reaction layer and an establishment of a region where diffusion limited ion exchange occur in these glasses during exposure to silica-saturated solutions. Different regions including reaction and diffusion regions were identified on the basis of the depth distributions of these elements. In the case of ceramics, damage accumulation was studied as a function of ion dose at different irradiation temperatures. A sigmoidal dependence of relative disorder on the ion dose was observed. The defect-dechanneling factors were calculated for two irradiated regions in SrTiO₃ using the critical angles determined from the angular yield curves. The dependence of defect-dechanneling parameter on the incident energy was investigated and it was observed that the generated defects are mostly interstitial atoms and amorphous clusters. Thermal recovery experiments were performed to study the damage recovery processes up to a maximum temperature of 870 K.