淀粉在木材胶粘剂中的应用

介绍了淀粉在木材胶粘剂中的应用,主要论述了淀粉作为改性剂可以有效地改善脲醛树脂胶的预压及胶合性能,可以加快聚醋酸乙烯酯的固化速度及提高耐水性。以淀粉为原料合成木材用胶粘剂主要通过加入异氰酸酯、三聚氰胺和苯酚衍生物改性或将淀粉氧化成双醛淀粉通过缩聚改性。     

木结构双自攻钉协同抗拔力试验研究

为了研究木结构中的自攻钉的抗拔性能,选用中国产普通圆钉、进口规格木材和普通木材,制作了6个木结构剪力墙中钉连接的试件,采用单调加载方式进行试验研究,结果表明普通圆钉连接强度主要取决于破坏模式;契入效应不足明显影响钉连接的强度;钉连接刚度离散性较大;故而通过进一步的试验研究,得出中国产自攻钉抗拔连接强度和刚度计算公式,将是十分必要的。     

落叶松锯材抗弯强度尺寸效应

以兴安落叶松锯材为研究对象,研究了不同目测等级下锯材尺寸与其抗弯强度之间的关系。试验选取1961根6.5、9.0和14.0cm 3种宽度尺寸的目测等级锯材,每个宽度尺寸分为高、低目测等级组,按照每组试件宽度18倍的测试跨度测试锯材的抗弯强度。利用斜率法和形状参数法确定高、低目测等级组抗弯强度5%分位值的长度与宽度的组合尺寸效应。研究结果表明,斜率法获得高、低目测等级组试件抗弯强度5%分位值的组合尺寸效应分别为0.19和0.23。     

真空高电压放电场木材干燥特性试验与研究

利用真空高电压放电场可节能、高效干燥木材,为研究不同高压脉冲形式下的干燥特性,分别对直流电压、交流电压、脉冲电压作用下的真空放电木材干燥及常规自然干燥和对流干燥进行比较试验。结果表明,通过调整电脉冲参数,使用真空放电法,能加速木材干燥过程。     

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.     

Nitration of Wood Cellulose in HNO_3/Organic Solvent Medium

Wood celluloseis a mainraw material for prepar-ing NC[1],there are different reactivities of the threehydroxyl groups in an anhydrogluose unit,in differ-ent positions along molecular chain and within differ-ent points of cellulose samples[2].Allowance shouldbe madefor the existenceincellulose of tworegions ofunequal accessibility to reactants.The“amorphous”regionis more or less freely accessible to all the con-stituents of the nitrating bath,and hydroxyl groupshere are esterified without any…     

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.