CO2激光用于船体型线放样切割的研究及应用

用激光打标和激光切割方法,实现对船舶建造中船体型线样板箱制作材料的划线与下料的工艺步骤.介绍了由激光器、数控系统、机床构架和冷水机组、除尘与空气压缩机组等辅助设备组成的龙门式三维激光加工联合机床的设计配置与工作原理,并通过对机床的操作试验,选定对木制材料加工的主要工艺参数,并对影响加工质量的现象进行了分析.     

六种木材的微波处理实验研究*

微波处理可以破坏木材的微观结构,有效提高木材的流体渗透性。为探究微波处理木材流体渗透性改善机理,同时为人工林木材的功能化改性研究提供理论依据,文章对杉木、落叶松、樟子松、毛白杨、泡桐及尾巨桉六种木材进行微波处理实验。从扫描电镜图片中可以看出,微波处理后,微波处理材会产生射线薄壁细胞之间或与轴向组织的胞间层处产生破坏、闭塞纹孔的打开、纹孔膜破坏、细胞壁破坏及内含物重新分布等变化。微观结构的破坏导致处理材力学性能下降。其中,微波处理后樟子松、杉木、落叶松、尾巨桉、毛白杨及泡桐的抗弯弹性模量(MOE)较处理前分别下降了31.1%、35.4%、45.6%、5.5%、24.4%和23.2%;抗弯强度(MOR)分别下降了38.4%、29.4%、67.2%、9.1%、34.0%和29.1%。同时,不同树种木材中不同的微观结构破坏形式造成处理材不同的吸水性测试结果。而根据微波处理材的吸水性及力学性能测试结果,可以选择适合用于微波处理后进行功能化改性处理的树种。     

Effects of increased wood energy consumption on global warming potential,primary energy demand and particulate matter emissions on regional level based on the case study area Bavaria (Southeast Germany)

Wood energy use has strongly increased in Europe in the last decade entailing enhanced resource competition between the wood energy sector and the material-based wood sector. We applied the basket of benefit method for the forestry and wood cluster of the study area Bavaria to evaluate the impact of increased wood energy use and decreased material-based wood use on global warming potential, primary energy demand and particulate matter emissions. A baseline and a wood energy scenario were developed until 2035 and wood utilization in both scenarios was assessed via a Life Cycle Assessment of prevalent wood products, imported timber and conventional alternatives of use. The study reveals that, according to the modelled scenarios and the average substitution factors used, a demand shift towards more wood energy leads to a minor increase in global warming potential and to a reduction in primary energy demand. Increase in particulate matter emissions from wood energy use is strong, but definite conclusions cannot be drawn due to lack in data for material-based wood use. Moreover, the study results vary strongly depending on the products used for the comparative analysis. Through our approach, the ecological impact of increased wood energy use becomes visible for a whole region, taking into account the effect of a demand shift and of interdependent substitution effects.     

大功率白光LED封装技术对器件寿命的影响

通过功率LED器件封装工艺技术的改进来降低芯片结温,从而减缓器件光衰速率,延长其预期的工作寿命时间。对用于封装的关键原材料的选取进行了对比实验,指出了采用纳米级材料改进导热可降低热阻,论述了正确选用混胶材料和工艺,可以减缓器件光衰速率,达到在较高的环境温度条件下,器件使用寿命大于50 000 h。论述了器件芯片的结温对光、电、色性能的影响和不同结温其预期工作寿命时间也不同的关联性。     

网格环境下信任机制的研究

本文介绍了网格环境下信任机制的重要性,给出了信任的定义、特性和分类,并重点描述了行为信任机制的研究方法。文章最后给出了行为信任机制在网格环境下的典型应用场景。     

碲镉汞薄膜少子寿命测试研究

碲镉汞(HgCdTe)材料的少子寿命是影响碲镉汞红外探测器性能的重要参数.分别采用微波光电导衰减(Microwave Photoconductivity Decay,μ-PCD)法和微波探测光电导(Microwave Detected Photoconductivity,MDP)法对 HgCdTe 薄膜的少子寿命进行了...     

高精度光波导损耗测试系统的设计与实现

以波导耦合理论为依据,采用棱镜耦合法设计了集光电为一体的高精度波导损耗测量系统。测量以激光为光源,采用双光路法,消除了通用检测仪由于光源光强不稳定产生的误差,使得测量结果只与光强的相对变化量有关;光波出入波导均采用棱镜耦合,减少了普通测试方法因样品质量及面形误差和端面洁净情况不同或输出透镜不能很好汇聚光波而产生的误差;利用常规仪器设备实现了数字化检测显示,避免了人为主观读数产生的误差; 利用AD538实时模拟计算芯片,提高了计算精度和运算速度。     

矿用输送带与木材燃烧性能的对比实验研究

利用锥形量热计对氯丁胶（CR）、聚氯乙烯塑料（PVC）输送带与木材的点燃性能、热释放性能、烟气毒性和烟气的减光性等进行了对比实验研究。结果表明,木材与CR,PVC输送带相比点燃时间较长,热释放速率介于两之间,CO生成率和比消光面积较小;CR输送带的火灾危险性远大于PVC输送带和木材,但PVC输送带的CO生成率较高,对比实验为矿井火灾火源特性数学模型的建立以及矿用阻燃输送带的开发提供了基础参数。     

Estimation of bitumen emulsion dispersion using a light scattering method

Petroleum bitumen in the emulsified state is widely used as a binder in road and civil construction. Along with traditional quality parameters of bitumen emulsions the particle size is considered to be very important characteristic. The particle size of the dispersed phase affects the setting rate and viscosity of bitumen emulsions. The complete data on the particles size distribution can be obtained using such technical methods as light scattering and microscopy. In the study bitumen emulsions with three types of surfactants (cationic, nonionic, zwitterionic) have been prepared and their viscosity and decay index have been determined. The emulsions also have been studied with a microscope, as well as by the method of dynamic light scattering. The dynamics of particle size changes of the bitumen emulsions has been compared with the dynamics of the change in the basic parameters of the emulsions, such as viscosity and decay index, and the correlation between them has been found. Thus, using a modern laser and optical equipment, it is possible to estimate the quality of emulsions and, if necessary, to correct their composition.     

粉末冶金无镍奥氏体不锈钢的渗氮研究

在粉末冶金无镍奥氏体不锈钢的烧结冷却过程中,以气体渗氮方式对其进行渗氮处理.通过对其渗氮层金相组织的观察及力学性能和耐腐蚀性能的测试,结果表明,随着渗氮温度的升高,奥氏体不锈钢随炉冷却时析出物增多,其表层氮含量和表面硬度先增加后趋于平缓,抗弯强度先增加后下降并趋于稳定,而耐腐蚀性降低.