等离子体微表处理胶粉改性沥青工艺条件优化分析

为提高橡胶回收再利用效率,进一步改善胶粉改性沥青路用性能,采用等离子微表处理方法对胶粉进行活化处理。处理工艺条件（包括功率和时间）对胶粉改性沥青的性能影响较为关键,利用不同处理功率和处理时间分别制备了9组等离子微表处理胶粉的改性沥青,通过比较其针入度、软化点以及动态剪切试验结果,探究不同条件对胶粉改性沥青性能影响的规律,进而结合灰关联模糊评价模型确定等离子体微表处理方法的最佳工艺条件。研究结果表明：采用40目胶粉且其质量掺量为15%时,处理功率和处理时间与关联度值存在线性增长关系,且随着处理功率或时间的增加,均有胶粉改性沥青的针入度降低,软化点升高的趋势;在70℃温度下,等离子体活化胶粉的改性沥青车辙因子G^*/sin（δ）值呈现增大趋势,表明等离子微表处理技术可有效改善胶粉改性沥青的高温稳定性,且性能受到功率和时间显著影响。灰色关联模糊评价方法分析结果显示：排序关联度值最大为0.920 8,可以确定等离子体处理方法最佳处理功率和处理时间分别为250 W和8 min。结合处理工艺条件与关联度值拟合结果可知,功率拟合线斜率比时间拟合斜率更大,与处理时间相比,处理功率对于胶粉改性沥青高温性能影响更大。     

激光点火在天然气发动机中的应用

介绍了天然气发动机激光点火的基本工作原理、基本过程、不同的引燃点火方式以及影响激光点火的3个特性参数(气体不均一指数、水的吸光度、火焰发射);对激光点火系统与传统的火花塞点火系统在天然气发动机燃烧和排放性能方面进行了燃烧持续期、失火极限、敲缸极限、NOx排放等参数的比较;总结了激光点火的优缺点及其在天然气发动机中的应用前景。     

等离子体焊接枪的数值模拟

以等离子体钨极氩弧焊接枪为研究对象,通过求等离子体弧柱区域的能量方程、动量守恒、质量守恒及电流连续性方程,得到温度、速度、电流密度分布。数值模拟200A自由氩弧所得电弧等离子体温度分布与实验数据相当吻合。在此基础上研究了带有喷嘴的弧柱部分的数值模拟,以及温度、速度和电流密度的分布、电弧弧长和最高温度的关系。     

Ablation of Barrett's esophagus using the second-generation argon plasma coagulation

Objective To investigate the efficacy and safety of the second-generation argon plasma coagulation (VIO APC) in ablation of Barrett's esophagus. Methods Eighteen patients with Barrett's esophagus (12 males, median age of 55 years, median length of 2.1 cm,1 low-grade dysplasia, 13 cases of short segment Barrett's esophagus) received VIO APC, which was performed at a power setting of 40W and argon gas flow at 1. 5-2. 0 L/min, "forced" mode, in 1-3 sessions (mean 1.3). All the patients received treatment with high-dose proton pump inhibitors. The main complaints before ablation were upper abdominal pain in 12 patients (66%), sour regurgitation in 14 patients (77%), and dysphagia or odynophagia in 7 patients (38%). Two patients (11%) had esophageal hiatal hernia. Results The percentage of patients in whom ablation was endoscopically achieved proximal to the gastroesophageal junction was 77. 8%(14/18), and histologically achieved in 66. 7% (12/18). Berried glands were observed in 2 patients who had achieved endoscopic ablation, the areas of Barrett's mucosa were reduced by more than 60% in the other 4 patients. After treatment, 4 patients had transient retrosternal pain and 3 patients had mild epigastric discomfort. One patient had small amounts of hemorrhage during the process, and it ceased after norepinephrine and thrombosin were administered through endoscope biopsy channel. No esophageal stricture or other severe adverse events was observed. During 11.8 (4-15) months' follow-up, the patients who had achieved the complete ablation had no evidence of relapse of Barrett's esophagus. Conclusion VIO APC with a relatively low power setting can effectively ablate the Barrett's mucosa with special intestinal metaplasia when standard APC has been done. No severe adverse events were observed. Long-term follow-up is needed to assess cancer prevention and the durability of the neo-squamous epithelium.     

不同柔性纤维砂浆在凝固过程中裂缝开展性能比较

混凝土早期开裂是工程中普遍存在的现象,裂缝严重影响了混凝土的耐久性,是混凝土研究中的一个热门话题。通过对几种柔性纤维砂浆试件在凝固过程中裂缝开展性能比较试验,研究不同柔性纤维在相同掺量工况下对砂浆试件的阻裂效果,为桥梁的设计、施工和加固提供了一定的参考。     

气门锥面等离子喷焊钴基合金层的高温磨损特性研究

为适应高温、腐蚀、冲击载荷等恶劣的工作条件,采用等离子喷焊方法在气门锥面制备了钴基合金涂层。在气门模拟磨损试验机上进行了磨损试验,用扫描电镜观察了焊层磨损面的组织形貌,用能谱仪分析了焊层磨损面的成分,测试了焊层磨损后的硬度变化。结果表明,该喷焊层具有良好的耐高温磨损性能。     

船用排气净化低温等离子体反应器设计研究

根据对现有的尾气处理技术的分析,介绍一种尾气处理的新技术:介质阻挡放电低温等离子体技术。对低温等离子体技术的原理和基本结构进行探讨,并分别就低温等离子体技术与催化净化技术结合进行具体研究。研究表明,低温等离子体净化技术与催化净化技术结合,可以克服现有催化净化技术的不足,有效提高发动机尾气颗粒物、碳氢化合物和氮氧化物的净化效率,且具有广泛的应用前景。     

特低频对潜通信系统研究

特低频通信的工作频率在0．001Hz到5Hz之间，其信号可以穿透250米深的海水而保证能量没有明显的衰减。这种对海水极强的穿透能力和遍及全球的传播范围，使特低频通信成为丫实现陆地与潜艇之间通信的有效手段。按照特低频频谱特性，特低频信号产生、传播、接收过程的顺序介绍特低频对潜通信系统的研究与应用。     

快速原型制造技术探讨和应用

综合运用计算机辅助设计和制造技术、激光技术和材料学技术,在没有传统模具和夹具的情况下,快速制造出任意复杂形状而又具有一定功能的三维实体模型或零件。     

FLICKER INDEX METHOD FOR EVALUATING FLICKER IN COLOR PDPs

Motionartifacts ,thenumberofvisiblegraylevelsandlargeareaflickerarethemainissuesaf fectingimagequalityincolorPDPs[1] .Thehighlyflickeringimagescausemoreseverefatigueofbrainthanofeyes[2 ] .Inordertoreduceflickereffectively ,theframerateand/orhorizontalfrequencyaredoubledtopreventlargeareaflickerinsuchCRTtelevisionsets.However ,itisundesirabletoadoptframerateconversiontechnologyincolorPDPswhenaddressdisplayseparated (ADS)drivingmethodisused[1] .Athigherframerate ,lesstimeisavailableperframe…