Based on abnormalities in tear film structure and dynamics,dry eye syndrome is primarily classified into five types:aqueous-deficient,mucin-deficient,evaporative/lipid-deficient,tear dynamics disorder,and mixed type.T...Based on abnormalities in tear film structure and dynamics,dry eye syndrome is primarily classified into five types:aqueous-deficient,mucin-deficient,evaporative/lipid-deficient,tear dynamics disorder,and mixed type.The disease has diverse triggers,commonly including:lacrimal gland dysfunction;meibomian gland dysfunction accelerating tear evaporation;reduced blinking due to prolonged electronic device use;contact lens wear interfering with the tear film;medication side effects;environmental factors;hormonal fluctuations;certain ophthalmic surgeries,for example,LASIK.Treatment requires targeting specific pathogenic mechanisms,with the core focus on controlling inflammation,restoring tear film stability,and improving related gland function.展开更多
Based on the method of compound and additional conditions under the conditions of the equal temperature rise and the equal potential drop (P.D.) of resistance, the application of design software of dry-type air-core r...Based on the method of compound and additional conditions under the conditions of the equal temperature rise and the equal potential drop (P.D.) of resistance, the application of design software of dry-type air-core reactor is introduced in this thesis. The analytical methods of the inductance are also given. This approach is proved entirely feasible in theory through the simplification with Bartky transformation, and is able to quickly and accurately calculate reactor inductance. This paper presents the analytical methods of the loss of dry-type air-core reactor as well.展开更多
Compared with the traditional wet-type de-dusting technology ,the dry-type de-dusting technology is considered to be environmentally friendly and energy-saving. However, the pipes carrying the de-dusted blast fiLrnace...Compared with the traditional wet-type de-dusting technology ,the dry-type de-dusting technology is considered to be environmentally friendly and energy-saving. However, the pipes carrying the de-dusted blast fiLrnace gas （BFG） tends to be corrosive more quickly and seriously. In order to investigate the reasons for the quick corrosion, the gas pipes and auxiliary bellows installed in Baosteel＇ s newly built BFG dry-type de-dusting system are studied. The corrosive properties of the condensed water, such as the pH value, are measured and analyzed. Meanwhile, various factors that may influence the corrosion rate of the pipes are studied by experiment. On the basis of the investigation and research, the causes of corrosion and leakage on the pipes are discovered. It is the process of dry de-dusting that is responsible ,to a large extent, for the quick corrosion of the pipes. The equipment of spray tower is introduced and its effects are then discussed. This tower is designed to eliminate most of chloridion and neutralized the acid by spraying the alkaline water to the dedusted gas flow. The practical operation shows that the tower helps to lessen the corrosiveness of the dry de-dusted gas effectively. The last part of this study analyzes the possible impacts of the dry-type de-dusting process of the newly built blast furnace （BF） on the main BFG piping which has been in the state of being corroded for years by estimating its potential corrosion rate, and some suggestions on maintenance are given as well.展开更多
Environmental requirements world wide and in the P.R.of China in particular have increased and authorities are increasing the pressure on steelmakers to comply with always more stringent limits and standards. Modern c...Environmental requirements world wide and in the P.R.of China in particular have increased and authorities are increasing the pressure on steelmakers to comply with always more stringent limits and standards. Modern converter steel making goes along with the innovation and new developments not only for the primary converter process itself but even more for the dedusting technologies.This paper describes the benefits and latest development of advanced off gas cleaning and recovery systems based on dry type cleaning with electrostatic precipitation and wet type gas cleaning based on wet scrubbers.Modern converter dedusting is based on suppressed combustion systems in order to reduce off gas amounts and to be able to use the gas for gas recovery.The dry type primary off gas treatment system based on electrostatic precipitator technology is the most advanced environmental solution available for converter steel making.Dry dedusting has been introduced in China successfully with a significant contribution by Siemens VAI being the market leader for converter dry dedusting systems.Siemens VAI has introduced several design improvements over the last years such as CFD modeling of flow conditions in evaporation cooler,design of chains for dust conveyors,design of ESP inlet,design and thickness of discharge electrodes and operation in energy saving mode.Additionally the DDS process has been successfully implemented in China for the De-P process.The gas recovery system for DDS has been optimized over the years with high quality equipment and integrated automation and control systems.Wet type dedusting for converter gas is a well proven technology for many years and is still widely used due to the simplicity of the process and the lower investment costs.SVAI has continuously improved it's wet dedusting technologies to provide highly energy efficient systems which can achieve lowest levels of clean gas dust while still maintaining a moderate water and energy consumption with simplified process control and standardized process control packages.Main design and process improvements include expansion joints for connection of scrubber to cooling stack,new type of droplet separator,advanced hood pressure control package,ID fan washing system,ID fan speed control system etc.The focus for wet type gas recovery systems is still on maximum safety and reliability.SVAI has also successfully improved the technological packages for converter gas recovery for wet type dedusting systems.The comparison between the two system shows the advantages of dry dedusting mainly being the lowest clean gas dust content, lower operating costs,easier handling for recycling of residuals and no need for a water treatment plants.Wet type dedusting has it's main advantages in the simple process and operation of the system,the flexible layout solutions inside the steel shop as well as generally lower investment costs.An overview on the numerous reference installations for dry- and wet type dedusting systems in China as well as world wide is given.展开更多
免灌浆干式连接预应力混塔竖缝界面采用环氧树脂结构胶+弯螺栓施加预紧力共同抗剪,相比传统的灌浆湿连接+连接钢筋的形式,可以极大地提高现场安装效率。为此,针对干式连接竖缝界面的抗剪性能,以足尺试件为研究对象,开展1个直剪静力试验...免灌浆干式连接预应力混塔竖缝界面采用环氧树脂结构胶+弯螺栓施加预紧力共同抗剪,相比传统的灌浆湿连接+连接钢筋的形式,可以极大地提高现场安装效率。为此,针对干式连接竖缝界面的抗剪性能,以足尺试件为研究对象,开展1个直剪静力试验和两个直剪疲劳试验。研究竖缝界面在静力剪切荷载作用下的破坏模式、黏结滑移曲线及承载力计算,进一步重点分析竖缝界面的疲劳破坏模式、剪切刚度退化及疲劳寿命计算方法。试验研究和理论分析结果表明:干式连接竖缝的静力、疲劳试验均发生脆性破坏模式,界面可分为界面脱黏破坏和混凝土保护层剥离破坏两类区域,面积占比约各50%,弯螺栓施加预紧力可以有效提高结构胶界面的黏结抗剪能力;荷载上限是影响竖缝剪切疲劳性能的关键因素,且疲劳寿命与荷载上限呈负相关;竖缝界面的抗剪能力由混凝土直接抗剪和弯螺栓预紧力产生的摩擦力共同提供,根据叠加法推导的竖缝界面受剪承载力计算公式具有较高的精度;Fib Model Code规范公式可以对竖缝的剪切疲劳寿命进行预测,预测结果具有较高的准确性和一定的安全富余,具有良好的工程应用价值。展开更多
【目的】干式空心电抗器(dry-type air-core reactor,DAR)在运行中易发生匝间短路故障,该类故障具有隐蔽性强、难以实时察觉的特点,对电网的安全稳定运行构成严重威胁。工程中广泛采用的基于磁感应强度幅值的检测方法存在局限性,其对内...【目的】干式空心电抗器(dry-type air-core reactor,DAR)在运行中易发生匝间短路故障,该类故障具有隐蔽性强、难以实时察觉的特点,对电网的安全稳定运行构成严重威胁。工程中广泛采用的基于磁感应强度幅值的检测方法存在局限性,其对内层绕组匝间短路的响应不灵敏,且在多台DAR并列运行时,邻近设备产生的磁场干扰会显著影响检测准确性。为提升故障识别能力并实现早期预警,本文提出一种基于磁场方向角(magnetic field direction angle,MFDA)的DAR匝间短路检测方法。【方法】基于有限元仿真技术,模拟了单相DAR在正常运行及不同位置发生匝间短路时的周围磁场分布;通过在DAR周围设置多个监测点,采集磁感应强度数据,分析了故障发生前后磁感应强度的变化规律;依据磁场叠加原理,计算并分析了三相DAR中故障相附近各监测点MFDA的时序变化规律;对比单台与多台DAR并列运行的MFDA数据,量化评估了邻近正常运行DAR对故障检测的干扰程度,并优化了监测点的布局。【结果】仿真结果表明,单相DAR发生匝间短路后,其周围的磁感应强度幅值和方向均发生了显著变化;与基于幅值的检测方法相比,MFDA对匝间短路表现出更高的响应灵敏度,能够准确捕捉故障所引起的电磁特性变化;通过分析故障发生前后各监测点MFDA的时序变化并设定故障判定阈值,可实现单相DAR匝间短路的诊断;对于三相DAR并列运行场景,在故障相附近、正常相对称中垂线上设置监测点,可有效减少邻近DAR的磁场干扰,结合MFDA时序特征与故障判定阈值,仍能实现短路故障诊断。【结论】提出的基于MFDA的检测方法能够有效弥补磁感应强度幅值检测法在灵敏度和抗干扰能力方面的不足,为DAR运行状态的实时监测与故障预警提供了一种可靠的技术手段。该方法基于仿真研究,展现出良好的工程应用潜力,对提升电网设备运维水平、保障电力系统安全稳定运行具有实际应用价值。展开更多
文摘Based on abnormalities in tear film structure and dynamics,dry eye syndrome is primarily classified into five types:aqueous-deficient,mucin-deficient,evaporative/lipid-deficient,tear dynamics disorder,and mixed type.The disease has diverse triggers,commonly including:lacrimal gland dysfunction;meibomian gland dysfunction accelerating tear evaporation;reduced blinking due to prolonged electronic device use;contact lens wear interfering with the tear film;medication side effects;environmental factors;hormonal fluctuations;certain ophthalmic surgeries,for example,LASIK.Treatment requires targeting specific pathogenic mechanisms,with the core focus on controlling inflammation,restoring tear film stability,and improving related gland function.
文摘Based on the method of compound and additional conditions under the conditions of the equal temperature rise and the equal potential drop (P.D.) of resistance, the application of design software of dry-type air-core reactor is introduced in this thesis. The analytical methods of the inductance are also given. This approach is proved entirely feasible in theory through the simplification with Bartky transformation, and is able to quickly and accurately calculate reactor inductance. This paper presents the analytical methods of the loss of dry-type air-core reactor as well.
文摘Compared with the traditional wet-type de-dusting technology ,the dry-type de-dusting technology is considered to be environmentally friendly and energy-saving. However, the pipes carrying the de-dusted blast fiLrnace gas （BFG） tends to be corrosive more quickly and seriously. In order to investigate the reasons for the quick corrosion, the gas pipes and auxiliary bellows installed in Baosteel＇ s newly built BFG dry-type de-dusting system are studied. The corrosive properties of the condensed water, such as the pH value, are measured and analyzed. Meanwhile, various factors that may influence the corrosion rate of the pipes are studied by experiment. On the basis of the investigation and research, the causes of corrosion and leakage on the pipes are discovered. It is the process of dry de-dusting that is responsible ,to a large extent, for the quick corrosion of the pipes. The equipment of spray tower is introduced and its effects are then discussed. This tower is designed to eliminate most of chloridion and neutralized the acid by spraying the alkaline water to the dedusted gas flow. The practical operation shows that the tower helps to lessen the corrosiveness of the dry de-dusted gas effectively. The last part of this study analyzes the possible impacts of the dry-type de-dusting process of the newly built blast furnace （BF） on the main BFG piping which has been in the state of being corroded for years by estimating its potential corrosion rate, and some suggestions on maintenance are given as well.
文摘Environmental requirements world wide and in the P.R.of China in particular have increased and authorities are increasing the pressure on steelmakers to comply with always more stringent limits and standards. Modern converter steel making goes along with the innovation and new developments not only for the primary converter process itself but even more for the dedusting technologies.This paper describes the benefits and latest development of advanced off gas cleaning and recovery systems based on dry type cleaning with electrostatic precipitation and wet type gas cleaning based on wet scrubbers.Modern converter dedusting is based on suppressed combustion systems in order to reduce off gas amounts and to be able to use the gas for gas recovery.The dry type primary off gas treatment system based on electrostatic precipitator technology is the most advanced environmental solution available for converter steel making.Dry dedusting has been introduced in China successfully with a significant contribution by Siemens VAI being the market leader for converter dry dedusting systems.Siemens VAI has introduced several design improvements over the last years such as CFD modeling of flow conditions in evaporation cooler,design of chains for dust conveyors,design of ESP inlet,design and thickness of discharge electrodes and operation in energy saving mode.Additionally the DDS process has been successfully implemented in China for the De-P process.The gas recovery system for DDS has been optimized over the years with high quality equipment and integrated automation and control systems.Wet type dedusting for converter gas is a well proven technology for many years and is still widely used due to the simplicity of the process and the lower investment costs.SVAI has continuously improved it's wet dedusting technologies to provide highly energy efficient systems which can achieve lowest levels of clean gas dust while still maintaining a moderate water and energy consumption with simplified process control and standardized process control packages.Main design and process improvements include expansion joints for connection of scrubber to cooling stack,new type of droplet separator,advanced hood pressure control package,ID fan washing system,ID fan speed control system etc.The focus for wet type gas recovery systems is still on maximum safety and reliability.SVAI has also successfully improved the technological packages for converter gas recovery for wet type dedusting systems.The comparison between the two system shows the advantages of dry dedusting mainly being the lowest clean gas dust content, lower operating costs,easier handling for recycling of residuals and no need for a water treatment plants.Wet type dedusting has it's main advantages in the simple process and operation of the system,the flexible layout solutions inside the steel shop as well as generally lower investment costs.An overview on the numerous reference installations for dry- and wet type dedusting systems in China as well as world wide is given.
文摘免灌浆干式连接预应力混塔竖缝界面采用环氧树脂结构胶+弯螺栓施加预紧力共同抗剪,相比传统的灌浆湿连接+连接钢筋的形式,可以极大地提高现场安装效率。为此,针对干式连接竖缝界面的抗剪性能,以足尺试件为研究对象,开展1个直剪静力试验和两个直剪疲劳试验。研究竖缝界面在静力剪切荷载作用下的破坏模式、黏结滑移曲线及承载力计算,进一步重点分析竖缝界面的疲劳破坏模式、剪切刚度退化及疲劳寿命计算方法。试验研究和理论分析结果表明:干式连接竖缝的静力、疲劳试验均发生脆性破坏模式,界面可分为界面脱黏破坏和混凝土保护层剥离破坏两类区域,面积占比约各50%,弯螺栓施加预紧力可以有效提高结构胶界面的黏结抗剪能力;荷载上限是影响竖缝剪切疲劳性能的关键因素,且疲劳寿命与荷载上限呈负相关;竖缝界面的抗剪能力由混凝土直接抗剪和弯螺栓预紧力产生的摩擦力共同提供,根据叠加法推导的竖缝界面受剪承载力计算公式具有较高的精度;Fib Model Code规范公式可以对竖缝的剪切疲劳寿命进行预测,预测结果具有较高的准确性和一定的安全富余,具有良好的工程应用价值。
文摘【目的】干式空心电抗器(dry-type air-core reactor,DAR)在运行中易发生匝间短路故障,该类故障具有隐蔽性强、难以实时察觉的特点,对电网的安全稳定运行构成严重威胁。工程中广泛采用的基于磁感应强度幅值的检测方法存在局限性,其对内层绕组匝间短路的响应不灵敏,且在多台DAR并列运行时,邻近设备产生的磁场干扰会显著影响检测准确性。为提升故障识别能力并实现早期预警,本文提出一种基于磁场方向角(magnetic field direction angle,MFDA)的DAR匝间短路检测方法。【方法】基于有限元仿真技术,模拟了单相DAR在正常运行及不同位置发生匝间短路时的周围磁场分布;通过在DAR周围设置多个监测点,采集磁感应强度数据,分析了故障发生前后磁感应强度的变化规律;依据磁场叠加原理,计算并分析了三相DAR中故障相附近各监测点MFDA的时序变化规律;对比单台与多台DAR并列运行的MFDA数据,量化评估了邻近正常运行DAR对故障检测的干扰程度,并优化了监测点的布局。【结果】仿真结果表明,单相DAR发生匝间短路后,其周围的磁感应强度幅值和方向均发生了显著变化;与基于幅值的检测方法相比,MFDA对匝间短路表现出更高的响应灵敏度,能够准确捕捉故障所引起的电磁特性变化;通过分析故障发生前后各监测点MFDA的时序变化并设定故障判定阈值,可实现单相DAR匝间短路的诊断;对于三相DAR并列运行场景,在故障相附近、正常相对称中垂线上设置监测点,可有效减少邻近DAR的磁场干扰,结合MFDA时序特征与故障判定阈值,仍能实现短路故障诊断。【结论】提出的基于MFDA的检测方法能够有效弥补磁感应强度幅值检测法在灵敏度和抗干扰能力方面的不足,为DAR运行状态的实时监测与故障预警提供了一种可靠的技术手段。该方法基于仿真研究,展现出良好的工程应用潜力,对提升电网设备运维水平、保障电力系统安全稳定运行具有实际应用价值。
