Plasma spraying is an important enabling technology i n near-net-shaped process as well as many high-performance coating applicatio ns. Recently, it is being applied to rapid mould manufacturing to reduce develop ment...Plasma spraying is an important enabling technology i n near-net-shaped process as well as many high-performance coating applicatio ns. Recently, it is being applied to rapid mould manufacturing to reduce develop ment time and manufacturing cost. In this process, inputted powders are heated a nd accelerated by plasma jet, and impinge on master pattern or prototype to form ing a thick coating. Mould will be fabricated after backed-up with consolidated material and other post-treatments. Amongst numerous factors that affect the l ife and properties of mould made by this novel method, quality of coating is the most important one. However, the complex nature of the spray process results in a large number of processing parameters that must be controlled in order to obt ain optimum coatings. Traditional "trial and error" method is too time and cost consuming for the optimal processing parameters. Maybe modeling and diagnostics of process is the best way to ravel out the problems. It has been proved that pl asma-gas flowrate, power level and spray distance are the most critical variabl es. So flow visualization and diagnostics for plasma jet quality has become an i mportant task to obtain a repeatable and reliable plasma processing technology. Using enthalpy probe diagnostics, spectrometry and optical measurement, we can o btain the distribution of temperature field of plasma jet. These results can hel p us to design gun configuration and optimize processing parameters for high dep osition efficiency and good qualities of rapid mould manufacturing. Nevertheless , it is still very difficult to realize real-time diagnoses because of restrict of diagnosis condition and drawback of measurement approach. In our researches, a real-time data collection and image processing system for plasma jet with high temperature, velocity and compressed energy has been realiz ed by CCD sensor. In this paper, we firstly focus our attention on collection pr inciple and methods, and an effective method for collecting data in high tempera ture area is presented. Then a system of real-time data collection by CCD camer a is developed. Finally, fake color image processing is given to analyze the law of temperature field distribution under different conditions. The results are i mportant to realize the visualization of plasma spraying, and especially to furt her study on closed-loop feedback control of forming quality for plasma rapid m anufacturing process.展开更多
基于涉及街道景观要素与街道可步行性关系的研究还存在一定缺失,以广州市天河区代表性综合街区华师-体育中心片区为对象,对城市街区的可步行性进行研究。综合马斯洛需求层次理论和“步行需求层次”模型,选取安全性、舒适性、社交性、美...基于涉及街道景观要素与街道可步行性关系的研究还存在一定缺失,以广州市天河区代表性综合街区华师-体育中心片区为对象,对城市街区的可步行性进行研究。综合马斯洛需求层次理论和“步行需求层次”模型,选取安全性、舒适性、社交性、美观性为指标建立街景特征评价指标体系。通过Insta360 ONE X2全景相机采集、图像语义切割、人机对抗模型评分、SPSS分析(Pearson相关性分析、多元线性回归分析)等多种方法,研究街景特征与可步行性关系。结果表明,4类街景特征与可步行性均具有一定相关性,其中,舒适性方面的绿视率对街道可步行性的影响最为显著。基于分析结果,街道空间可以从安全性、舒适性、社交性和美观性的街景特征层面进行步行性优化提升,如在安全性方面,建议增设护栏或绿化带,增设、整合标识牌等。展开更多
The Old Man and the Seais the representative work of the famous American writer Hemingway.It tells the adventure experience of an old Cuban fisherman fishing and fighting with nature.It has created a unique image of S...The Old Man and the Seais the representative work of the famous American writer Hemingway.It tells the adventure experience of an old Cuban fisherman fishing and fighting with nature.It has created a unique image of San Diego,contains profound philosophical thoughts and humanistic spirit,and is an important content of literary research.This article analyzes the characters in The Old Man and the Sea,hoping to deepen the understanding of this work.展开更多
文摘Plasma spraying is an important enabling technology i n near-net-shaped process as well as many high-performance coating applicatio ns. Recently, it is being applied to rapid mould manufacturing to reduce develop ment time and manufacturing cost. In this process, inputted powders are heated a nd accelerated by plasma jet, and impinge on master pattern or prototype to form ing a thick coating. Mould will be fabricated after backed-up with consolidated material and other post-treatments. Amongst numerous factors that affect the l ife and properties of mould made by this novel method, quality of coating is the most important one. However, the complex nature of the spray process results in a large number of processing parameters that must be controlled in order to obt ain optimum coatings. Traditional "trial and error" method is too time and cost consuming for the optimal processing parameters. Maybe modeling and diagnostics of process is the best way to ravel out the problems. It has been proved that pl asma-gas flowrate, power level and spray distance are the most critical variabl es. So flow visualization and diagnostics for plasma jet quality has become an i mportant task to obtain a repeatable and reliable plasma processing technology. Using enthalpy probe diagnostics, spectrometry and optical measurement, we can o btain the distribution of temperature field of plasma jet. These results can hel p us to design gun configuration and optimize processing parameters for high dep osition efficiency and good qualities of rapid mould manufacturing. Nevertheless , it is still very difficult to realize real-time diagnoses because of restrict of diagnosis condition and drawback of measurement approach. In our researches, a real-time data collection and image processing system for plasma jet with high temperature, velocity and compressed energy has been realiz ed by CCD sensor. In this paper, we firstly focus our attention on collection pr inciple and methods, and an effective method for collecting data in high tempera ture area is presented. Then a system of real-time data collection by CCD camer a is developed. Finally, fake color image processing is given to analyze the law of temperature field distribution under different conditions. The results are i mportant to realize the visualization of plasma spraying, and especially to furt her study on closed-loop feedback control of forming quality for plasma rapid m anufacturing process.
文摘基于涉及街道景观要素与街道可步行性关系的研究还存在一定缺失,以广州市天河区代表性综合街区华师-体育中心片区为对象,对城市街区的可步行性进行研究。综合马斯洛需求层次理论和“步行需求层次”模型,选取安全性、舒适性、社交性、美观性为指标建立街景特征评价指标体系。通过Insta360 ONE X2全景相机采集、图像语义切割、人机对抗模型评分、SPSS分析(Pearson相关性分析、多元线性回归分析)等多种方法,研究街景特征与可步行性关系。结果表明,4类街景特征与可步行性均具有一定相关性,其中,舒适性方面的绿视率对街道可步行性的影响最为显著。基于分析结果,街道空间可以从安全性、舒适性、社交性和美观性的街景特征层面进行步行性优化提升,如在安全性方面,建议增设护栏或绿化带,增设、整合标识牌等。
文摘The Old Man and the Seais the representative work of the famous American writer Hemingway.It tells the adventure experience of an old Cuban fisherman fishing and fighting with nature.It has created a unique image of San Diego,contains profound philosophical thoughts and humanistic spirit,and is an important content of literary research.This article analyzes the characters in The Old Man and the Sea,hoping to deepen the understanding of this work.
