基于乘积ARIMA模型的中日航线CCFI趋势预测

构建乘积ARIMA模型对中日航线CCFI时间序列的波动规律和趋势进行了拟合及预测,并进一步预测了中日航线受季节性、周期性等波动影响的运价数据,并将CCFI实际观测值与乘积ARIMA模型预测值进行了对照,检验结果显示该模型能够较准确地拟合CCFI时间序列的波动规律和发展趋势。     

新型“王权”156号游艇

“王权”号是由香港游艇制造商与唐纳得塔基和天青海军设计师共同合作完成的一款新型游艇。这一155．8英尺的新型游艇设计吨位在500吨以内,便于在区域内的管理。     

筹建海事技术服务中心的构想

随着航海事业迅猛发展以及上海国际航运中心建设不断推进,海事业务与日俱增,海事司法评估、鉴定的作用日益凸现.航运界、政府职能部门和社会相关领域人士等对具有资质的社会第三方承担海事技术服务工作的呼声日渐高涨.此外,随着上海自由贸易试验区的落地,国家鼓励设立第三方检验鉴定机构,按照国际标准采信其检测结果.航运经济的发展催促了海事评估、咨询社会化力量的兴起,并为其提供了广阔的发展空间.     

世界上最大的风力发电厂投入运行

瑞典Vattenfall公司在英国东南海岸建造的萨尼特海上风力发电场投入运行,该发电场是世界上最大的海上风力发电厂。该风电场有100组发电涡轮机,能够产生英国20多万户家庭的年均消费总量。     

High Efficiency and Quality of Multi-Pass Tandem Gas Metal Arc Welding for Thick Al 5083 Alloy Plates

Multi-pass tandem gas metal arc welding(TGMAW) for Al 5083 alloy plates with 30 mm thickness is carried out to study its high efficiency and high quality. The welding process is evaluated by high-speed photographs and electrical signals. The deposition rate and welding time are calculated to characterize the welding efficiency. The bead formation, porosity, microstructure and mechanical properties are tested and analyzed. The results indicate that though arc deflection occurs due to the electromagnetic interference between two arcs during TGMAW process, it does not affect the welding process stability significantly. The deposition rate and welding time of TGMAW process are about 15 g/min larger and about 16.7% less than those of gas metal arc welding(GMAW)process respectively, accompanied by the reduction of heat input. The TGMAW welded joint has less porosity and more refined microstructure to contribute to the improvement of mechanical properties(micro-hardness, tensile strength and ductility). It can be concluded that TGMAW process yields excellent performance of welded joint with improved welding efficiency, which makes it extremely practical during welding of thick plates.