多层石墨烯在飞秒激光作用下的损伤

使用飞秒激光对化学气相沉积(CVD)法制备的多层石墨烯进行辐照,得到了多层石墨烯的单脉冲破坏阈值为0.22mW;利用光学显微镜、原子力显微镜(AFM)和拉曼光谱对加工前、后的试样进行表征,阐述了飞秒激光对多层石墨烯的烧蚀损伤效应,发现飞秒激光在石墨烯微图案化加工方面具有潜在的优势,能够达到亚微米级的加工精度;同时在烧蚀边缘区域,多层石墨烯出现减薄现象。     

吡嗪分子多维振动动力学中Non-Condon效应

采用优化控制理论和多组态含时Hartree结合的方法,研究了吡嗪分子在3个电子能级之间振动耦合模型中Non-Condon效应的影响;在非绝热近似下给出了跃迁偶极函数的具体形式,成功实现了Non-Condon效应下对吡嗪分子的飞秒激光控制;给出了不同初始能量下飞秒激光的优化图形,得到了整个电子态的布居和相应的优化激光脉冲形状。同Condon近似下的结果进行比较发现:跃迁偶极矩的不同方向对电子波函数的影响较大,相应的优化激光场的振荡周期也发生了改变。     

那素达滴眼液治疗飞秒激光制瓣术后眼部刺激征的临床疗效研究

目的:探讨那素达滴眼液治疗飞秒激光制瓣后眼部刺激征的临床疗效。方法:采用随机双盲方法进行自身对照研究,选取60例(120眼)接受飞秒激光手术的近视患者,双眼经飞秒激光制瓣后,一眼立即滴用那素达滴眼液为观察组,另眼不滴用那素达滴眼液为对照组。在等待气泡吸收的10分钟内,观察双眼的眼部刺激症状以及术中的配合程度。结果:观察组12眼(20%)出现眼部刺激征,对照组38眼(63.3%)出现眼部刺激征,两组间差异有统计学意义(χ2=25.503,P<0.05)。观察组在术中的配合度优于对照组(χ2=24.014,P<0.05)。结论:那素达滴眼液能有效缓解飞秒激光制瓣后的眼部刺激征,提高配合度。     

受不同加载偏转角影响的含裂纹砂岩劈裂声发射试验研究

目前,岩石声发射方向性存在与否尚无定论,岩石中裂纹的存在对岩石声发射方向性是否存在影响也无深入的研究。针对完整的和含有一条预制裂纹的砂岩圆盘试件,分别偏转5°,10°,15°,35°,60°角进行岩石声发射方向性验证劈裂试验,对比分析了不同加载偏转角度下完整砂岩和含预制裂纹砂岩的声发射特征。研究表明:(1)偏转角度的不同对砂岩声发射Kaiser效应确有影响,随着偏转角度的增大,砂岩声发射Kaiser效应逐渐模糊直至消失,证明在此试验条件下砂岩的声发射Kaiser效应方向性随着偏转角度的增大而愈加明显。(2)含裂纹砂岩的Kaiser效应方向性比完整砂岩的Kaiser效应方向性更明显,具体表现为含裂纹砂岩的声发射Kaiser效应比完整砂岩在偏转过程中消失得更快。研究成果可为利用Kaiser效应测量地应力的可行性和准确性提供试验论证。     

桥梁拉索损伤声发射监测及其临界损伤判断

通过拉伸试验,得到了钢绞线整个损伤过程的声发射特征参数,测试结果表明：采用计数、能量、持续时间、幅值和时间的相关点图来综合表征损伤,不但可以跟踪全过程损伤,而且还可以准确判断出断丝信号和非断丝信号以及断丝位置,并发现钢绞线在屈服变形之前,声发射特征参数并不明显,屈服阶段之后,声发射的特征参数逐渐增大,在临近断裂时,声发射特征参数迅速增大。最后采用声发射特征参数时间序列分形理论研究了钢绞线的损伤演化规律,在加载初中期,分形维数变化不大,当钢绞线裂纹进入快速扩展阶段,分形维数出现“最大-最小”变化模式,运用此模式可为钢绞线临界损伤破坏提供一个新的判据。     

飞秒激光和角膜刀制瓣LASIK矫正屈光不正的临床疗效及术后视觉质量比较

目的:探讨飞秒激光和角膜刀制瓣LASIK矫正屈光不正的临床疗效及术后视觉质量。方法:选取本院2015年4月-2016年4月收治的68例屈光不正患者为研究对象,按照前瞻性随机临床对照方法,将患者分为对照组和观察组,各34例。对照组接受角膜刀(SBK刀)制瓣LASIK治疗,观察组接受飞秒激光制瓣LASIK治疗。观察两组患者的治疗效果,同时,记录两组患者术前、术后屈光变化、总高阶像差并进行比较。结果:两组患者术后裸眼视力比较,差异均无统计学意义(P>0.05)。两组患者术后屈光变化、总高阶像差均较术前有显著改善,且观察组术后均显著优于对照组,差异均有统计学意义(P<0.05)。观察组患者制瓣厚度、制瓣成功率、剩余角膜厚度均显著优于对照组,差异均有统计学意义(P<0.05)。结论:飞秒激光和角膜刀(SBK刀)制瓣LASIK矫正屈光不正均有显著的效果,但飞秒激光LASIK术后高阶像差较低,安全性和稳定性较高,有利于提高患者视觉治疗,值得推广。     

岩石声发射的Kaiser效应研究进展

简要介绍了声发射技术的原理、发展史,从Kaiser效应应用方面,还介绍了声发射技术的研究成果.还介绍了岩石的Kaiser效应及声发射技术在岩土工程中的应用.最后讨论了声发射技术未来的研究方向.     

激光经纬仪在高层建筑施工测量中的使用

激光经纬仪是利用激光的光亮度和单色性方向性的特点引用到测量中的。目前,国内生产的激光经纬仪是在J_2级光学经纬仪的望远镜筒上,装置具He—Ne(氦氖)气体激光器,通过一组导光系统把经纬仪望远镜的光学系统联系起来,组成激光发射的光学系统,再配上激光电源,便构成了激光经纬仪。当激光经纬仪配有90°读数管目镜,即可应用到高层建筑工程测量中。 激光经纬仪广泛应用于水利、桥梁、船舶制     

砂岩在循环荷载作用下的Felicity效应研究

通过不同循环载荷水平作用下对砂岩变形特征的试验研究,探讨了砂岩在循环载荷作用下的状态参数、物性参数和声发射信息规律。试验结果表明:(1)砂岩在不同加、卸载阶段所产生的应变变化量不断增加,即随着加载水平的提高塑形变形加大;(2)砂岩在闭合阶段同样产生明显的声发射效应,而在卸载阶段未发现声发射现象;(3)砂岩在反复加、卸载过程中产生明显的Felicity效应;在每个应力水平下Felicity比不一样,应力水平越低,Felicity效应越明显,随着应力水平的增加,砂岩的各个物性和状态参数的Felicity效应有不断增大的趋势。     

激光加工技术在工程机械制造中的应用探讨

介绍激光加工技术,分别阐述激光切割、激光打标和激光焊接相对于传统制造技术所具有的优势,重点探讨推土机主机架激光填丝焊、变速器齿轮激光焊,以及利用激光焊接技术实现工程机械驾驶室的流线型设计的可行性.阐述激光加工技术在未来制造业发展中的重要性.     

浅析高速公路工程招投标中的最低评标价法

结合目前高速公路施工项目招投标活动的实际情况,阐述了最低评标价法的概念,归纳了其优点及存在问题,对完善最低评标价法提出几点策略,以期促进招标投标市场更加规范有序。     

Place-Making in Megaprojects in Melbourne

This article analyses state-led place-making practices in Melbourne. The two levels of government that influence planning in Melbourne make much of the city as ‘culturally vibrant’ and ‘creative’, and have incorporated creative city-inspired place-making principles into many layers of the planning system. An examination of the development of two mixed-use megaprojects in central Melbourne reveals however that ideals of culturally engaging public places, and indeed of creative landscapes for middle-class consumption, wither in the face of more basic imperatives for economic development. In these case studies the ‘creative city’, no matter how the idea is interpreted, has little traction either as a set of inclusive place-making principles or as a gentrification strategy. The article concludes that the creative city-inspired place-making objectives in the planning system at both state and local levels are ambiguous in their overall intents and completely unsupported by statutory controls. Such place-making objectives as are realised are the compromised results of the interplay of uncoordinated decisions, delivered at the pleasure of the developer.     

Pathogens in septage in Vietnam

Septage is widely acknowledged as a major source of infectious pathogens while disposal of septage, and the operation and maintenance of septic tanks, is not regulated in many developing countries. Twenty untreated septage and septage sludge samples were taken from Can Tho City, Vietnam to examine their pathogen content, and indicator micro-organisms. Escherichia coli and Enterococcus spp. were detected in all samples, regardless of sludge storage time. Phages were detected in 80% of samples. Salmonella spp. were detected in 70% of the untreated septage and 60% of septage sludge samples. Concentrations of phages and bacteria tested in septage sludge after many years of tank storage were much higher than the expected levels. Helminth ova were present in 95% of untreated septage samples with an average of 450 ova l^− 1, and were detected in all septage sludge samples with an average of 16,000 ova l^− 1. Twelve varieties of helminth ova were identified. More helminth ova varieties in higher concentrations were found in septage than those reported from stool samples. The varieties' frequency ranged from 10% to 50% and Ascaris lumbricoides predominated. Results show that pathogens and indicator micro-organisms, especially helminth ova, accumulate in sludge. Thus helminth ova should be considered when septage sludge is treated and used for agriculture. Proper health protection measures must be applied for people handling septage.     

在市场中实践在实践中学习在学习中进步--工程公司市场化进程的回顾与展望

近两年来，工程公司在提高市场竞争意识、推动市场化进程中做了大量工作，其中坚持走出去的方针是我们自我加压、推行加快市场化步伐的一个重要战略步骤。     

新时期广东城市化的新特点

新时期广东城市化出现以下特点:知识源导向、城市由单体向群体化发展、产业集群推动、政府主导自上而下的集约化发展、城镇化向城市化转变、由重“数量”发展向重“质量”发展的转变。     

新形势下高校强化基建财务管理的探讨

在市场条件下高校基建财务人员在加强日常财务管理的同时,必须树立起高度的工作责任心,抓好事前监督、事中监督、事后监督三个环节,全面理解、贯彻执行《高等学校财务制度》,管好用好各项基本建设资金,提高基建财务管理水平,更好地完成高校各项基建任务,以有限的投资,最快的建设速度,获得最大的投资效益。     

2005年北京办公物业市场七大趋势

趋势一:CBD区域写字楼集中放量从各区域规划方案上看,CBD区域多数项目在03～04年处于项目的报批手续及拆阶段,预计2005年正式推向市场,因此2005年CBD区域将成为北京市场供应集中的域,区域即将供应的项目有北京财富中心(二期)、金地国际花园、万达广场、SOHO尚都、万通中心、世纪财富中心、怡禾国际中心、光华国际等。除去未知项目,2005CBD写字楼办公面积的供应量为60万平方米左右。中关村区域经过一段时间的集中供后开始逐步放缓,2005年供应的体量相对较大的项目有中关村金融中心、新中关。金街区域可能开盘的项目只有2个:英蓝国际中…     

浅谈我国工程项目建设成本控制存在的问题

结合目前我国施工企业工程项目成本管理现状,对工程项目成本管理过程中存在的问题进行了较详细的分析,并提出了一些解决问题的办法,以做好项目成本控制工作,进而增强企业经济实力。     

Variation in property taxation in Tulsa

Conclusions It may be reasonably concluded from this study that the range of variation in these ratios of assessed to actual value are of a reasonable size for the great majority of cases. The frequency distribution of these sample ratios was not normal, however, as was assumed a process of this type would produce. On the other hand, the failure of the regression analysis to identify any significant variables which would explain these variations would tend to re-enforce the assumption that the fluctuations were indeed of a random nature.To sum it up in one paragraph, aside from a few extreme cases, the assessing process appears to give estimates which are more consistent than would be expected under the assumption that any errors would be of a random nature, but the regression analysis was unable to isolate any particular socioeconomic characteristics which would explain the variation which was present.Financial support for this research project was furnished by the University of Tulsa.