2195 aluminum-lithium alloy was widely applied in the aviation and aerospace industry, but it is highly susceptible to pitting and intergranular corrosion undergoing sever corrosive circumstance and moisture atmospher...2195 aluminum-lithium alloy was widely applied in the aviation and aerospace industry, but it is highly susceptible to pitting and intergranular corrosion undergoing sever corrosive circumstance and moisture atmosphere. To solve this problem and consequently to prolong its service life, a multi-step-heating-rate(MSRC) process was carried out. Investigations were carried out to find the effect of the MSRC process on the alloys corrosion resistance. It is found that the MSRC process is more favorable for the uniform phase precipitation by comparing the corrosion resistance of samples treated by traditional heat treatments. The potential difference between phases can be reduced and intergranular corrosion is able to be prohibited efficiently. Besides, the rare earth infiltration is beneficial to improving the corrosion resistance. As heating time increases, the corrosion resistance declines gradually, samples treated by artificial aging and solid solution also exhibit a better corrosion resistance.展开更多
An analytical queuing model is proposed for the classified services of WiMAX network. Simulation model is also developed that corresponds to the Markovian analytical model using Java modeling tool （JMT）. This is a n...An analytical queuing model is proposed for the classified services of WiMAX network. Simulation model is also developed that corresponds to the Markovian analytical model using Java modeling tool （JMT）. This is a new and efficient discrete event tool for queuing network modeling and workload analysis. QoS metrics have been evaluated for the multi-rate traffic in multiple scenari- os. Results obtained from simulation are compared for validation and analysis. Outcomes show that the proposed model is more efficient than the conventional method by improving residence time, re- sponse time, increasing system throughput and efficiency at queuing level with a slight degradation in call acceptance factor.展开更多
随着全球制造业竞争的日益激烈,我国提出了“中国制造2025”制造强国战略,其重点发展的十大领域中,与焊接技术密切相关的就高达八个,不仅极大地推动了焊接技术的革新发展,而且对焊接效率和质量均提出了更高的要求。由于熔化极气体保护焊...随着全球制造业竞争的日益激烈,我国提出了“中国制造2025”制造强国战略,其重点发展的十大领域中,与焊接技术密切相关的就高达八个,不仅极大地推动了焊接技术的革新发展,而且对焊接效率和质量均提出了更高的要求。由于熔化极气体保护焊(Gas metal arc welding,GMAW)易于实现自动化焊接,具有生产效率高、焊接质量好及位置适应性好等优点,所以广泛应用于机械制造业中。实现高效GMAW的主要途径有提高焊接速度以及焊接熔敷率。针对以上两种途径,国内外焊接工作者在双丝GMAW的基础上,引入了第三根甚至多根焊丝,研发了各种多丝GMAW工艺。本文针对国内外研发的各类多丝GMAW工艺进行了分析,重点介绍了多丝GMAW工艺的焊接原理、工艺特点及其应用,通过上述分析对各类多丝GMAW工艺进行归纳总结,并进一步展望了多丝焊接的发展方向,即多丝GMAW工艺亟需在电弧物理理论、设备开发和新焊材研发等方面展开深入的研究工作。展开更多
传统的偏最小二乘方法(partial least squares,PLS)因未对建模数据求取均值轨迹,以及没有考虑多单元生产对浸出率的综合作用,导致无法准确建立过程信息与质量变量之间的回归关系。根据高铜矿氰化浸出过程的多单元和耗时长的特点,提出一...传统的偏最小二乘方法(partial least squares,PLS)因未对建模数据求取均值轨迹,以及没有考虑多单元生产对浸出率的综合作用,导致无法准确建立过程信息与质量变量之间的回归关系。根据高铜矿氰化浸出过程的多单元和耗时长的特点,提出一种针对连续过程的基于多单元均值轨迹的浸出率预测方法。获取建模数据的均值轨迹矩阵,在此基础上分别建立每个单元与实测浸出率的回归模型。定义输入向量与每个单元建模数据的相似度以及预测模型的权重,将各单元预测结果加权综合作为最终预测值。将该方法应用于氰化浸出过程浸出率预测,仿真结果表明,该方法体现了生产过程实际物理特性,提高了模型的解释能力,增强了预测模型的泛化性能。展开更多
基金Project(51471050105HK0101) supported by the National Key Laboratory of Precision Thermal Treatment, Harbin Institute of Technology,China
文摘2195 aluminum-lithium alloy was widely applied in the aviation and aerospace industry, but it is highly susceptible to pitting and intergranular corrosion undergoing sever corrosive circumstance and moisture atmosphere. To solve this problem and consequently to prolong its service life, a multi-step-heating-rate(MSRC) process was carried out. Investigations were carried out to find the effect of the MSRC process on the alloys corrosion resistance. It is found that the MSRC process is more favorable for the uniform phase precipitation by comparing the corrosion resistance of samples treated by traditional heat treatments. The potential difference between phases can be reduced and intergranular corrosion is able to be prohibited efficiently. Besides, the rare earth infiltration is beneficial to improving the corrosion resistance. As heating time increases, the corrosion resistance declines gradually, samples treated by artificial aging and solid solution also exhibit a better corrosion resistance.
基金Supported by the National Natural Science Foundation of China(60772066)
文摘An analytical queuing model is proposed for the classified services of WiMAX network. Simulation model is also developed that corresponds to the Markovian analytical model using Java modeling tool （JMT）. This is a new and efficient discrete event tool for queuing network modeling and workload analysis. QoS metrics have been evaluated for the multi-rate traffic in multiple scenari- os. Results obtained from simulation are compared for validation and analysis. Outcomes show that the proposed model is more efficient than the conventional method by improving residence time, re- sponse time, increasing system throughput and efficiency at queuing level with a slight degradation in call acceptance factor.
文摘随着全球制造业竞争的日益激烈,我国提出了“中国制造2025”制造强国战略,其重点发展的十大领域中,与焊接技术密切相关的就高达八个,不仅极大地推动了焊接技术的革新发展,而且对焊接效率和质量均提出了更高的要求。由于熔化极气体保护焊(Gas metal arc welding,GMAW)易于实现自动化焊接,具有生产效率高、焊接质量好及位置适应性好等优点,所以广泛应用于机械制造业中。实现高效GMAW的主要途径有提高焊接速度以及焊接熔敷率。针对以上两种途径,国内外焊接工作者在双丝GMAW的基础上,引入了第三根甚至多根焊丝,研发了各种多丝GMAW工艺。本文针对国内外研发的各类多丝GMAW工艺进行了分析,重点介绍了多丝GMAW工艺的焊接原理、工艺特点及其应用,通过上述分析对各类多丝GMAW工艺进行归纳总结,并进一步展望了多丝焊接的发展方向,即多丝GMAW工艺亟需在电弧物理理论、设备开发和新焊材研发等方面展开深入的研究工作。
文摘传统的偏最小二乘方法(partial least squares,PLS)因未对建模数据求取均值轨迹,以及没有考虑多单元生产对浸出率的综合作用,导致无法准确建立过程信息与质量变量之间的回归关系。根据高铜矿氰化浸出过程的多单元和耗时长的特点,提出一种针对连续过程的基于多单元均值轨迹的浸出率预测方法。获取建模数据的均值轨迹矩阵,在此基础上分别建立每个单元与实测浸出率的回归模型。定义输入向量与每个单元建模数据的相似度以及预测模型的权重,将各单元预测结果加权综合作为最终预测值。将该方法应用于氰化浸出过程浸出率预测,仿真结果表明,该方法体现了生产过程实际物理特性,提高了模型的解释能力,增强了预测模型的泛化性能。
