多纤芯弹性光网络中虚拟网络映射模型及算法

为解决多纤芯弹性光网络虚拟化中的虚拟结点映射、链路映射和频谱分配问题,首先建立了一个以最小化占用的频谱数及最小化最大占用频隙号为目标的全局约束优化模型.其次,设计了具有高效的交叉、变异及不可行解可行化算子的全局优化遗传算法,以有效求解该模型得到最优的虚拟节点、链路映射方案.最后,为验证算法的有效性进行了不同的仿真实验.结果表明,所设计的算法能够有效地减小网络中占用的频谱数和最大占用频隙号.     

一个典型弹性梁方程涉及第一特征值的正解

运用锥理论和不动点指数方法,在与相应的线性算子第一特征值有关的条件下,获得了一个典型弹性梁方程正解的存在性,改进了相关文献的结论.     

2020年细胞力学热点回眸

 概述了2020年细胞力学研究的热点和进展，探讨了细胞膜表面张力、细胞粘附力、细胞弹性模量、细胞与纳米颗粒相对刚度等对细胞生物学行为的影响及其在疾病诊疗中的应用。     

Short‐term salmon price forecasting

This study establishes a benchmark for short‐term salmon price forecasting. The weekly spot price of Norwegian farmed Atlantic salmon is predicted 1–5 weeks ahead using data from 2007 to 2014. Sixteen alternative forecasting methods are considered, ranging from classical time series models to customized machine learning techniques to salmon futures prices. The best predictions are delivered by k‐nearest neighbors method for 1 week ahead; vector error correction model estimated using elastic net regularization for 2 and 3 weeks ahead; and futures prices for 4 and 5 weeks ahead. While the nominal gains in forecast accuracy over a naïve benchmark are small, the economic value of the forecasts is considerable. Using a simple trading strategy for timing the sales based on price forecasts could increase the net profit of a salmon farmer by around 7%.     

波动方程在半无穷柱体和外部区域上的空间爆破和衰减性

利用能量分析的方法, 首先考虑定义在三维半无穷柱体上的波动方程, 当空间变量趋于无穷时, 证明其解或者指数式增长或者指数式衰减; 其次, 考虑定义在球面外部区域上的波动方程, 证明其解随半径的二择一结果； 最后, 证明对于非线性弹性方程, 二择性定理仍有效.     

LDPC 码改进型LBP 译码算法研究

针对LDPC(Low Density Parity Check) 码分层( LBP: Layered Belief Propagation) 译码算法计算复杂度高、不易于硬件实现的问题, 提出一种改进算法。该算法首先引入函数f(x)使LBP译码算法的计算复杂度大大降低; 同时引入具体参数校正因子和偏移因子, 提升译码性能。仿真结果表明, 改进后的算法相比LBP 算法在计
算复杂度降低的同时, 也提升了译码性能, 从而达到了易于硬件实现的目的。     

非线性弹性杆波动方程的精确解

通过假设2个非线性弹性杆波动方程的行波解,得到其常微分方程,运用Exp函数法,并借助Mathematica软件,获得了这2个非线性弹性杆波动方程的精确解.     

半空间上水平层状场地自振频率计算方法比较

为避免结构物与场地地基的共振效应,基于传统波速法、一致质量矩阵剪切质点系法及剪切梁法的基本原理,分析和比较了各方法计算场地自振频率的计算精度和影响因素.结果表明:传统波速法不能反映土层剖面结构特征的影响,而且仅在土层剖面在深度方向较为对称的情况下才能获得工程可接受的精度;一致质量矩阵剪切质点系法则表现出计算稳定、精度高的特点,且作为一种离散方法,具有良好的计算适应性和灵活性.     

Janus few layered graphene with asymmetric wettability as anti-flooding cathode supports in proton exchange membrane fuel cells

Water balance in cathode catalyst layer (CCL) is crucial for proton exchange membrane fuel cells (PEMFCs). Herein, we report a novel strategy to develop a Janus few layered graphene particles (FLGP) with asymmetric wettability by varying the carbon precursors in the chemical vapor deposition (CVD) process. Using the Janus FLGP supported Pt with asymmetric wettability as the cathode of a PEMFC, a peak power density of 632 mW cm⁻² was achieved, which was about two-folds of the hydrophobic FLGP and three-folds of hydrophilic FLGP based cathode, respectively. The enhanced performance could be ascribed to the well-constructed three-phase boundary in an anti-flooding cathode, leading to enlarged electrochemical active surface area and facilitated mass transfer. This work may provide new clues for improving water management in PEMFCs.     

Propagation patterns of microseismic waves in rock strata during mining: an experimental study

Microseismic monitoring has been widely used in mines for monitoring and predicting dynamic disasters such as rockbursts and waterbursts. However, to develop high-precision microseismic monitoring systems, the propagation patterns of microseismic waves under complex geological conditions must be elucidated. To achieve this aim, a simulation model of a typical coalmine was designed using similar materials according to the similarity theory to simulate the mining process. Geophones were embedded into the model to detect the propagation of elastic waves from microseisms. The results show that in an unmined solid rock mass, the wave velocity in shallow rock strata is mainly affected by geologically weak planes, whereas in deep strata it is affected mainly by the density of the rock mass. During propagation, the amplitude first decreases and then increases rapidly with increasing propagation distance from the coal layer. After mining, our results indicate that the goaf causes significant attenuation of the wave velocity. After the goaf was backfilled, the velocity attenuation is reduced to some extent but not eliminated. The results of this study can be used as guidelines for designing and applying microseismic monitoring systems in mines.