啁啾脉冲放大系统中空间滤波器小孔尺寸的设计

为了获得啁啾脉冲放大系统(CPA)中空间滤波器的小孔尺寸,可以利用傅里叶光学的方法和激光模式理论,通过数学上的合理近似和对能量频谱函数的数值积分,计算激光束中基横模和主要低阶横模的径向空间频谱与空间截止频率,并讨论以基横模的空间截止频率作为空间滤波器的截止频率的可行性,从而确定小孔光阑孔径的大小并得出一个具有普遍意义的结论,即小孔直径约取6.93倍衍射极限长度时,空间滤波器能够较好地滤去TEM00模以外其他横模的大部分高频能量成分,从而提高光束质量,此结果在实验上得到很好的验证。此外,以M2因子为基础,可以得到一个用以辅助描述空间滤波器滤波性能的光束质量改善因子B。     

基于结构相似度的图像融合质量评价

在分析现有图像融合质量评价方法特点的基础上,提出了新型的、基于结构相似度的图像融合质量评价方法.针对不同情况,分别采用平均结构相似度、加权平均结构相似度、结构信息与交互信息量之乘积作为图像融合质量客观评价标准.该方法充分考虑了图像的结构信息和人类视觉系统的特性,可以为不同场合下选择不同的算法提供依据.对不同融合算法的质量评价结果表明,该方法是一种有效的图像融合质量评价方法.     

Fresh Basil Infusion: Effect of Sous-Vide Heat Treatment on Their Volatile Composition Profile,Sensory Profile,and Color

Herbs, including basil, are used to enhance the flavor of food products around the world. Its potential is influenced by the quality of fresh herbs and processing practices, wherein conditions of heat treatment play an important role. The aim of the research was to determine the effect of sous-vide heat treatment on the volatile compounds profile, sensory quality, and color of basil infusions. The material used for research was aqueous basil infusion prepared conventionally at 100 °C, and using the sous-vide method (65, 75, and 85 °C). The composition of volatile compounds was identified by GC/MS analysis, the sensory profile was assessed using a group of trained panelists, while the color was instrumentally assessed in the CIE Lab system. No significant differences were found in the intensity of the taste and aroma of basil infusions at different temperatures. Seventy headspace volatile compounds were identified in the analyzed samples, ten of which exceeded 2% of relative area percentage. The most abundant compounds were eucalyptol (27.1%), trans-ocimene (11.0%), β-linalool (9.2%), and β-myrcene (6.7%). Most of the identified compounds belonged to the terpenes and alcohols groups. Our findings show that the conventional herbal infusion was more like a sous-vide infusion prepared at the lowest temperature SV₆₅, while SV₇₅ and SV₈₅ were similar to each other but different from the conventional. However, a smaller number of volatile compounds in the samples heated at higher temperatures of sous-vide were identified. The sous-vide samples showed a higher content of alkanes. The sous-vide method (p ≤ 0.05) resulted in darker, less green, and less yellow basil leaves than fresh and traditionally steeped ones. Long heat treatment under vacuum at higher temperatures causes a pronounced change in the aroma composition.     

晶界结构及其对力学性质的影响(Ⅱ)

<正> 3 晶界结构对力学性质的影响 晶界是固体材料中的一种面缺陷.由于晶界和位错以及其他缺陷和杂质之间的相互作用      

杭州五大名泉的成因、水质及其利用和保护问题

对于杭州五大名泉虎跑泉、龙井泉、玉泉、郭婆井和吴山井,明、清两代地方志中曾相继记载,近期又有学者陆续对其进行研究.但始终未见有系统论述.今笔者根据多年积累的实地调查资料和实验室测试结果,对这五大名泉的缘起、成因、水化学特征进行全面认识,并对它们的水质作一综合评价.为适应当前杭州旅游事业的发展和城市环保工作的深入需要,笔者还对如何开采、利用和保护这些名泉提出了切实、可行的建议.     

影响乙二醇中紫外透过率组分的测定

作为聚酯原料的乙二醇有一特殊的紫外透过率指标,如其不合格将影响产品的色相和白度。本文采用ＧＣ／ＩＴＤ方法分别测定不同质量的乙二醇样品,并捡出不合格样品中含有吗啉乙醇和吗啉丙醇。该物质紫外吸收光谱与不合格乙二醇紫外吸收光谱相似。还了解到在乙二醇制造工艺中确实有添加吗啉以降低酸性的情况,在生产中停止添加后产品的紫外透过率立即合格,证实了鉴定的正确性。     

Field air analysis with SPME device

Solid-phase microextraction (SPME) devices were used for a wide scope of air-monitoring including field sampling and analysis of volatile organic compounds (VOCs), formaldehyde, and particulate matter (PM) in air. Grab (instantaneous) and time-weighted average (TWA) sampling were accomplished using exposed and retracted SPME fibers, respectively. Sampling time varied from 1 to 75 min, followed by analysis with a gas chromatograph (GC). A portable GC equipped with unique, in-series detectors: photoionization (PID), flame ionization (FID), and dry electrolytic conductivity (DELCD), provided almost real-time analysis and speciation for common VOCs during an indoor air quality surveys. Indoor air samples collected with SPME devices were compared with those collected using conventional National Institute for Occupational Safety and Health (NIOSH) methods. Air concentrations measured with the SPME device were as low as 700 parts-per-trillion (ppt) for semi-volatile organic compounds. SPME methodology proved to be more sensitive than conventional methods, and provided a simple approach for fast, cost-effective sampling and analysis of common VOCs in indoor air. SPME technology combined with fast portable GC reduced the sampling and analysis time to less than 15 min. The configuration offered the conveniences of immediate on-site monitoring and decision making, that are not possible with conventional methods. In addition, SPME fibers were applied to sampling of particulate matter in diesel engine exhaust. Linear uptake and particulate build-up on the fiber were observed. Preliminary research suggests that SPME fibers could also be applied to sampling of airborne particulate matter.     

晶界结构及其对力学性质的影响(Ⅰ)

许多实验结果表明晶界对多晶材料的力学性能产生很大影响.本文简要总结了研究晶界结构及其对多晶材料力学性能的影响方面的理论和实验工作.第一部分介绍了描述晶界结构的各种模型,包括小角晶界位错模型,大角晶界重合点阵模型、O点阵模型和位移移动重位点阵理论,还讨论了晶界原子和电子结构,以及晶界结合力和晶界能.第二部分总结了晶界结构对力学性能的影响,包括强度,断裂韧度,蠕变,疲劳,沿晶断裂(应力腐蚀开裂,氢脆,液态金属腐蚀等).文中还介绍了最近发展起来的利用控制晶界结构改进多晶材料力学性能方面的新成果,晶界设计和毫微晶材料.      

基于联系数的预评模型在高铁客运站服务质量评价中的应用

高铁客运站服务质量评价是挖掘铁路运输服务中的薄弱环节的重要手段之一.针对现有评价系统的不完备性,将基于联系数的预评模型应用于高铁客运站服务质量评价中.模型通过计算评价系统的联系数,进一步计算出评价特征值来对高铁客运站服务质量进行评价,并利用集对势对服务质量的发展趋势作定性预测.将此方法应用于广州铁路集团衡阳东高铁站中,结果表明,模型具有较好的可操作性与可靠性,并兼顾评价与预测的功能,为高铁客运站服务质量评价工作的开展提供了一种新的理论方法.     

Microphotometric Detection of Particles/Inhomogeneities in Flowing Polymer Melts

By application of different unique microphotometric sensors it is possible to detect and quantify disturbing particles (gels, unmolten resins, black spots, additive agglomerates, bubbles) within a flowing polymer melt in realtime during extrusion processing. These particles result in disadvantageous optical and mechanical properties of a final polymer product. Sensors can be adapted inline and online to different extruders at various positions. This seems to give technical and economic benefit to quality control and process optimisation in polymer processing.