东风7B机车柴油机机油稀释故障处理的探讨

介绍了机油稀释的危害,分析了机油稀释的原因有：喷油泵漏泄、喷油器漏泄、回油管路漏泄等,并制定了检修工艺,解决了机油稀释的故障.     

Critical Analysis of Computing Equations for Determination of BOD by Dilution Methods

The dilution method has been accepted widely as the standard procedure for determining biochemical oxygen demand (BOD). A mass-balance approach was used to analyze four equations for computing BOD: two involving external seed correction methods (Standard Methods) and two involving internal correction methods (Sawyer and McCarty in 1978 and Kline and Gibbs in 1979). Five testing conditions were identified as being pertinent to the underlying assumptions: seed addition method, uniform BOD bottle volume, uniform initial dissolved oxygen (DO), seed uptake linearity, and data handling method. The results of this study showed that internal methods may provide more reproducible results, primarily due to the inherent correction for dilution water demand and better data handling (regression) technique to cope with the variation in BOD bottle volume and initial DO. However, internal methods may violate the requirements imposed by Standard Methods for minimum final DO (1?mg/L) for the high spike runs and minimum 5?day DO depletion (2?mg/L) for the low spike runs. Recommendations are also made to improve the reliability of these methods.     

Numerical investigation on the effects of dike around liquid hydrogen source on vapor cloud dispersion

Safety is one of the most important concerns in handling liquid hydrogen. Mixture model and Realizable k-ε model are adopted to simulate the spills of liquid hydrogen in the present work. Effects of a dike around the liquid hydrogen source on vapor cloud dispersion are numerically investigated. The dike increases the hydrogen concentration near the source, and promotes the upward movement of flammable cloud thanks to the enhanced mixing with air, reducing the cloud detachment distance. The time needed for the hydrogen vapor cloud to be diluted out of hazards is largely influenced by dike size, and introducing the dike does not necessarily increase the overall hazard duration. Increasing the height to length ratio of the dike makes the near-source region exposed to high hydrogen concentration for longer hazard duration, while detachment distance reduces with the increment in dike height.     

Optimization of Processing Parameters During Laser Cladding of ZE41A-T5 Magnesium Alloy Castings Using Taguchi Method

A continuous wave 4 kW Nd:YAG laser welding system was employed to clad single beads on machined 6.2-mm thick ZE41A-T5 aerospace magnesium alloy sand castings using nominal 1.6-mm filler rods of the parent metal. Based on the quality criterion of minimum dilution ratio, the Taguchi experimental method was used to optimize different process parameters and to identify the dominating factors. It was found that, for the process window investigated in this work, the optimal levels were 5.0 m/min for wire feed rate, 2.25 kW for laser power, and 2.5 m/min for cladding speed, with a minimum dilution ratio of 0.155. With 95% confidence, the wire feed rate is the dominating factor with the most significant influence on the dilution ratio. The dilution ratio usually decreases with increased wire feed rate while it increases with increased laser power. By contrast, the cladding speed appears to have insignificant influence on the dilution ratio over the cladding speed range used in this study.     

Biological phenol removal using immobilized cells in a pulsed plate bioreactor: effect of dilution rate and influent phenol concentration

The continuous aerobic biodegradation of phenol in synthetic wastewater was carried out using Nocardia hydrocarbonoxydans immobilized over glass beads packed between the plates in a pulsed plate bioreactor at a frequency of pulsation of 0.5s(-1) and amplitude of 4.7 cm. The influence of dilution rate and influent phenol concentration on start up and steady state performance of the bioreactor was studied. The time taken to reach steady state has increased with increase in dilution rate and influent phenol concentration. It was found that, as the dilution rate is increased, the percentage degradation has decreased. Steady state percentage degradation was also reduced with increased influent phenol concentration. Almost 100% degradation of 300 and 500 ppm influent phenol could be achieved at a dilution rate of 0.4094 h(-1) and more than 99% degradation could be achieved with higher dilution rates. At a higher dilution rate of 1.0235 h(-1) and at concentrations of 800 and 900 ppm the percentage degradation has reduced to around 94% and 93%, respectively. The attached biomass dry weight, biofilm thickness and biofilm density at steady state were influenced by influent phenol concentration and dilution rate.     

无底柱分段崩落法出矿贫化程度与矿石回收关系的研究

本文在实验基础上分析了无底柱分段崩落法出矿贫化程度与矿石回收的关系，得出了放矿正常后，采用不同贫化程度出矿，分段矿石回收率趋于一致的结论。研究表明，造成无底柱分段崩落法来出矿石贫比大的根本原因在于采用了不合理的截止品位放矿方式，无贫化放矿是无底柱分段崩落法最为理想的放矿方式。     

Prevention of substrate and product inhibitions by using a dilution strategy during dark fermentative hydrogen production from molasses

Substrate and product inhibitions have a significant effect on dark fermentative hydrogen gas production. Particularly, rapid formation of volatile fatty acids leads to fast pH decreases shifting the metabolic pathway. Therefore, controlling volatile fatty acid accumulation has great importance in maintaining effective hydrogen production. In this context, a dilution strategy was applied to regulate volatile fatty acids levels within the desired concentration range. A three-factor Box-Behnken statistical experiment design was established to assess the effects of dilution time, dilution percentage and initial COD concentration on hydrogen formation yield and rate. Highest hydrogen yield (7.7 mL H₂/mL_reactor) and rate (21. 47 mL H₂/h or 9.38 mmol/L_reactor.h) were achieved when 85 gCOD/L containing fermentation media was diluted with a percentage of 130 of the initial working volume at the 3rd hour of the fermentation period. Moreover, this strategy enabled to start fermentation with 55 g glucose/L.     

Tensile Properties and Fusion Zone Hardening for GMAW and MIEA Welds of a 7075-T651 Aluminum Alloy

Tensile and hardness values for 7075-T651 aluminum alloy in the as welded and post weld heat treated conditions（solubilization and artificial aging-T6）,obtained using GMAW and modified indirect electric arc（MIEA）welding processes are presented.Results showed that the base material along rolling direction exhibited a tensile strength of around 600 MPa and elongation of 11%.For the as welded condition,tensile strength was 260 MPa and elongation percent of 3%.This behavior was attributed to brittleness induced by the microstructural characteristics of the welded alloys,as well as high porosity.Hardness profiles along the welds were obtained and different welded zones were identified.A soft zone（＊100 HV0.1） in the heat affected zone for GMAW and MIEA was observed,the minimum hardness corresponding to weld metal（＊85 and ＊96 HV0.1for GMAW and MIEA,respectively）.The high dilution between filler and base metal during welding in MIEA allows to the Zn and Cu to flow from the base metal into the weld metal,inducing hardening by solution and subsequent artificial aging.In this regard,the hardness of the weld metal for MIEA increases by 56%,while the tensile strength reaches a value close to 400 MPa.For GMAW,non-favorable hardening effect was observed for the weld metal after solution and artificial aging.     

无焰燃烧技术的研究现状

无焰燃烧技术有设备简单、温度均匀、燃烧稳定、效率高和排放低等特点,被称为21世纪最有发展前景的燃烧技术之一。本文结合多篇国内外研究文献,总结了他们各自无焰燃烧方式的特点及其判定方法。接着列举了几种实现无焰燃烧的技术手段,包括充入氮气、高速射流和特殊燃烧室结构等。最后分别对气体燃料和固体燃料的无焰燃烧机理进行分析,从基元反应的角度说明了无焰燃烧排放低的原因,并列举了无焰燃烧技术在工业中的应用实例。     

全流稀释定容采样系统流量测量精度分析

本文研究并设计了一款柴油机颗粒排放全流稀释定容采样系统,采用了临界文丘里管做为的恒流装置,首次采用变频控制的罗茨风机做为动力源,并首次采用脉宽控制方式控制进入风机的排气恒温,大大提高了控制精度。本文对全流定容采样系统进行了流量测量精度的分析,研究表明,采用临界文丘里管做为全流稀释定容采样系统的恒流装置,精度完全可以达到法规要求。