基于结构诱导人工表面等离激元的宽带低耦合电路北大核心CSCD

实现超宽带传输和超高集成度设计是微波和太赫兹电路发展的终极目标。针对以上目标,本文提出了结构诱导人工表面等离激元的概念。基于此设计并验证了具有超高局附性和超小传输常数的结构诱导人工表面等离激元电路结构,打破了传统人工表面等离激元电路对传输常数和衰减常数的限制。理论分析和数值验证表明,相较于经典人工表面等离激元,具备优异的场局附性和传输特性的结构诱导人工表面等离激元具有明显的弱色散和低耦合特性,在电路设计中可以有效减少宽带信号传输的色散失真,同时提高布线密度。     

Commentary on Krishnaswamy et al. - Quantifying and mapping biodiversity and ecosystem services: Utility of a multi-season NDVI based Mahalanobis distance surrogate

Remote sensing is a powerful tool for characterizing, estimating or modelling species diversity. Differences in environmental properties of different habitats should lead to differences of spectral responses, which can be detected by satellite imagery. Hence, spectral distance may be related to species diversity. Based on previous studies, Krishnaswamy et al. [Krishnaswamy, J., Bawa, K. S., Ganeshaiah, K. N., & Kiran, M. C. (2009). Quantifying and mapping biodiversity and ecosystem services: Utility of a multi-season NDVI based Mahalanobis distance surrogate. Remote Sensing of Environment.] used spectral distance to estimate species diversity. Since a noisy scatterplot of species versus spectral diversity is expected, the commonly used Ordinary Least Square regression may fail to detect trends which occur across other quantiles than the mean.Krishnaswamy et al. [Krishnaswamy, J., Bawa, K. S., Ganeshaiah, K. N., & Kiran, M. C. (2009). Quantifying and mapping biodiversity and ecosystem services: Utility of a multi-season NDVI based Mahalanobis distance surrogate. Remote Sensing of Environment.] proposed a quantile-quantile plot method as an alternative to conventional regression based approaches which are inappropriate for dependent pair-wise dissimilarity or similarity data. By this commentary I demonstrate the utility of a quantile regression technique to complement the Krishnaswamy et al. [Krishnaswamy, J., Bawa, K. S., Ganeshaiah, K. N., & Kiran, M. C. (2009). Quantifying and mapping biodiversity and ecosystem services: Utility of a multi-season NDVI based Mahalanobis distance surrogate. Remote Sensing of Environment.] graphical approach in terms of a predictive model.     

高速公路不同养护策略的对比分析

以某高速公路长期养护为例,从结合预防性养护规划和单纯矫正性养护规划两个方面出发,建立两种长期的养护计划方案,得到两种养护方案下各路面性能指数的变化趋势.最后在高速公路的使用寿命、经济效益和路用性能三个方面,说明预防性养护在高速公路养护中的优越性,并倡导在高速公路养护中积极运用预防性养护.     

The retention of skills acquired through simulator-based training

This study examined the loss of skills across a nine month retention period following a simulator-based training programme developed to enhance the watchstanding skills of merchant marine cadets. The mitigation of decay as a function of a retraining experience was also evaluated. Two groups of merchant marine cadets were tested immediately preceding and following the programme and again nine months later. One group was given a refresher experience and tested six months into the retention interval. The evaluations were unobtrusive ratings of six watchstanding skill areas based upon performance during a 30-min simulated watchkeeping scenario. Generally, the results indicated that: (1) watchstanding skills improved following training; (2) skills declined over the nine month retention interval; and (3) refresher training was effective in terms of skill loss mitigation for some skill areas.     

徽州古民居无损检测技术与方法研究

无损检测技术是对徽州古民居结构构件检测的一种方便有效的方法.本文通过采用超声波技术对某栋徽州古民居的主要构件检测其存在的缺陷,并对无损检测方法和检测内容进行了归纳总结.通过检测得到数据,并对数据进行统计分析与归纳,提出了对徽州古民居检测的一些有益建议,为今后徽州古民居的检测、鉴定、修复提供技术参考.     

A novel approach to update summarization using evolutionary manifold-ranking and spectral clustering

Update summarization is a new challenge in automatic text summarization. Different from the traditional static summarization, it deals with the dynamically evolving document collections of a single topic changing over time, which aims to incrementally deliver salient and novel information to a user who has already read the previous documents. How to have a content selection and linguistic quality control in a temporal context are the two new challenges brought by update summarization. In this paper, we address a novel content selection framework based on evolutionary manifold-ranking and normalized spectral clustering. The proposed evolutionary manifold-ranking aims to capture the temporal characteristics and relay propagation of information in dynamic data stream and user need. This approach tries to keep the summary content to be important, novel and relevant to the topic. Incorporation with normalized spectral clustering is to make summary content have a high coverage for each sub-topic. Ordering sub-topics and selecting sentences are dependent on the rank score from evolutionary manifold-ranking and the proposed redundancy removal strategy with exponent decay. The evaluation results on the update summarization task of Text Analysis Conference (TAC) 2008 demonstrate that our proposed approach is competitive. In the 71 run systems, we receive three top 1 under PYRAMID metrics, ranking 13th in ROUGE-2, 15th in ROUGE-SU4 and 21st in BE.     

一类椭圆-抛物耦合方程组弱解的衰减估计

该文研究在热效应影响下半导体模型,它归结为一个非线性椭圆-抛物耦合方程组初边值问题.考虑此半导体方程瞬态解和稳态解之间的关系,通过对解的一系列估计,给出了在一定条件下瞬态解与稳态解的一个衰减估计.     

一类非线性抛物方程解的大时间性态

讨论N（N≥3）维全空间上一类非线性抛物方程解的大时间性态，利用经典的Fourier分解方法，证明了其解在L^2范数下的衰减速率为（1＋t）^-N/4，达到了和线性热传导方程解衰减率的一致性，因此在此意义下本文的结果是最优的。     

微生物对冰箱冷藏食品的影响研究

本文研究了微生物对冰箱冷藏食品的影响,研究表明,适冷菌在冰箱冷藏条件下可以生长繁殖,并引起食品腐败。在4℃冷藏条件下,新鲜生菜在冰箱冷藏室存放10天,在杀菌冰箱中生菜上的细菌总数由2.3×106cfu/g下降为4.6×104cfu/g,而在普通冰箱中,细菌总数由2.3×106cfu/g上升为为2.9×108cfu/g,普通冰箱食品上的细菌是杀菌冰箱食品上细菌的6304倍。研究表明,需要对冰箱冷藏食品进行微生物处理。     

TC2模型下中性top-pion衰变过程研究

在顶色辅助的人工色（TC2）理论模型中，研究了树图下中性top—pion（πt^0）的衰变过程πt^0→bb^-，tt^-，tc^-和圈图下中性top—pion（πt^0）的衰变过程πt^0→gg，γγ，γz，通过对这些衰变过程的衰变分支比的计算，可以得到πt^0在树图下的主要衰变过程为πt^0→tt^-，tc^-，在圈图下的主要衰变过程为πt^0→gg.对于小质量的中性top-pion（πt^0），可以用πt^0→tc^-来探测；对于大质量的中性top—pion（πt^0），可以用πt^0→tt^-来探测．中性top—pion（πt^0）是TC2模型中的特征粒子，通过对这些过程的研究可为在将来的直线对撞机上探测top—pion（πt^0）的存在提供理论依据。以此来检验TC2理论的正确性．