Effect of Intake Air Humidification and EGR on Combustion and Emission Characteristics of Marine Diesel Engine at Advanced Injection Timing

The trade-off between NO_x-soot and ISFC (Indicated Specific Fuel Consumption) brings new challenges for the development and application of innovative techniques that could reduce the NO_x-soot emissions of diesel engine simultaneously with the lowest possible fuel penalty.In this study,the two coupling measures,advanced SOI (start of injection) respectively coupled with intake air humidification (IAH) and EGR,were used to achieve lower NO_x-soot emissions than the original engine while minimizing the increase in ISFC.Numerical studies were conducted on a four-stroke supercharged intercooled marine diesel engine under 75%loads at 1350 r/min by using AVL Fire code.The advanced SOI varied from 14.5°CA BTDC to 20°CA BTDC;humidity ratio ranged from 0 to 100%in increments of 20%,and EGR rate ranged from 0 to 25%in increments of 5%.The technical route to achieve Tier III emission standards was also analyzed in this paper.The result indicates that lower in-cylinder pressure,temperature and NO_x emissions,higher ISFC and soot emissions are observed when only IAH or EGR technology is applied,while opposite trends are found when only using advanced SOI.The proper combination of different SOI respectively with humidity ratio and EGR rate can improve the trade-off relationship between NO_x and soot.Meanwhile,the increase in ISFC is improved by using advanced SOI under high EGR rate or humidity ratio.Compared with the advanced SOI coupled with EGR,advanced SOI coupled with IAH results in less loss of ISFC.Analysis results reveal that both above-mentioned coupling measures can achieve low NO_x-soot emissions while ensuring that ISFC does not increase.As expected,there are nine combinations of advanced SOI coupled EGR that can achieve NO emissions to meet the Tier III standard,while advanced SOI coupled IAH has only one combination to meet this regulation.     

T-NTRU物联网动态接入认证技术

物联网终端安全接入认证是保证电力物联网大规模建设的关键性技术.传统认证方案通常采用的椭圆曲线密码算法,计算量大,不能抵抗量子攻击.数论研究单元算法可以抵抗量子攻击,与椭圆曲线密码采用点乘算法相比,计算速度快.因此提出了一种时间变换数论研究单元算法物联网动态安全接入认证算法,使用动态变化时间序列通过哈希函数产生动态密钥,...     

BT36高温钛合金的成分特点及组织研究

采用金相观察和扫描能谱分析的方法,测定了BT36合金的α+β/β相转变温度和组织中不同区域的成分.结果表明:BT36合金的α+β/β相转变温度为980℃.其轧棒经过两相区热处理可获得等轴组织,同时存在片层状的β转变组织.经测定,与周围等轴基体相比,片层中Al含量偏低,而Mo、W含量偏高,这是由于合金在熔炼时合金元素没有得到充分地均匀化.     

滚筒采煤机固有频率的计算机仿真

滚筒采煤机的固有频率影响着振动形式和振动烈度,因此采用计算机仿真方法得到一般滚筒采煤机前几阶固有频率值,根据得到的结果给出改善其振动特性的建议,为后续进一步研究奠定基础。     

空气密度和湿度对雷电击距的影响

长距离高压输电线路贯穿不同海拔区域,而不同海拔区域的天气条件变化很大。采用电荷模拟方法对雷击水平导线进行建模,探讨了天气条件（空气密度和湿度）对雷电击距的影响,并导出了用于计算天气条件对接地水平导线击距影响的表达式。     

一个求解单调线性互补问题的不可行内点算法

基于核函数设计一个求解单调线性互补问题的不可行内点算法,在算法的每一步迭代中,只需要求解线性方程组得到新的搜索方向. 然后,按照一定的线性搜索规则,选择合适的步长得到新的迭代点.数值实验结果显示该算法是有效的.     

全棉紧密纱色织物的生产技术

介绍了紧密纱的特点和细特高密色织物的设计与开发过程,在此基础上对紧密纱色织物生产过程中各主要工序的工艺参数与技术措施作了详细阐述,其中重点探讨了紧密纱的上浆技术,认为应采取“小张力、低黏度、中压力、重浸透、低上浆、高回潮、少用PVA”的工艺原则。     

顾客满意度评价体系的建立及应用

介绍了顾客满意度评价体系的构建,该体系包括评价指标的构成、权重确定、顾客对评价指标态度的量化等,采用主观赋权等方法确定各评价指标的权重,将顾客对评价指标态度分为五个等级,并通过多层加权方法,给各等级相应赋值。通过对莱钢某产品顾客满意度定量测评,说明该评价体系对挖掘顾客价值取向、指导企业经营改进、开拓市场等方面的作用,并对该评价体系的运用作了进一步的探讨与思考。     

P91主蒸汽管道高硬度和低硬度焊缝性能研究

对P91钢的高硬度和低硬度焊缝的冲击功、硬度、断裂韧度和持久强度进行了试验研究,结果表明:硬度高、韧性低的R焊缝具有高的持久强度;硬度低、韧性高的D焊缝具有低的持久强度。材料持久强度的高低与部件的蠕变寿命密切相关。