State and Prospects of Diesel Engine Fault Diagnosis Technique

As a kind of complex power machinery, diesel engine is being paid more and more attention to its condition monitoring and fault diagnosis technology. In the fault diagnosis field of diesel engine, the technique of signal process, character abstraction and identification method have formed a system, but there is a certain distance away from practical. This paper analyzes the common faults and influencing factor of diesel engine. The principle, characteristic and disadvantage of modern fault diagnosis technology, such as various time-frequency methods based on vibration signal, speed fluctuation method, iron content and spectrometry, grey system theoretical diagnosis method, artificial neural network and expert system fault diagnosis method, were reviewed. The difficulties and the development direction of diesel engine fault diagnosis were put forward in the end.     

基于台架试验的渔船柴油机履行新排放标准探讨

环保部2016年发布了GB 15097—2016《船舶发动机排气污染物排放限值及测量方法（中国第一、二阶段）》,该标准相较于《渔业船舶法定检验技术规则（船长大于或等于12 m国内海洋渔业船舶2017）》的要求增加了一氧化碳、碳氢化合物、颗粒物3个控制项目,氮氧化物的排放限值也明显提高。为获知当前中国主流渔船柴油机排放的技术现状、了解履行新标准的差距,对2种典型的渔船柴油机进行了排放污染物测试试验和劣化试验验证。试验结果显示：典型渔船柴油机可满足新标准一阶段的要求,但距离二阶段要求有较大差距。其中颗粒物的排放超出二阶段限值25%~53%。通过两型柴油机试验数据的对比分析发现,燃油喷射方式是改善颗粒物排放和有效降低柴油机劣化程度的关键因素。针对渔船柴油机如何更好的履行二阶段排放要求给出建议：推迟新标准二阶段生效;鼓励研发新产品,促进先进技术引进;控制实船使用燃油质量,提高渔民的环保意识;加强实船监管力度。     

A New Method of Diesel Engine Fuel System Fault Diagnosis

A method of diesel engine fuel system fault diagnosis based on wavelet transform and fuzzy C-means clustering is presented. Five characteristic parameters of reflecting fault state are distilled with wavelet transform of pressure wave of high-pressure oil pipe of diesel. The theory and generic approach of fuzzy C-means clustering algorithm (FCM) is given, and the validity of evaluating fuzzy clustering making use of partition coefficient, partition entropy and parting coefficient is pointed out. Identification of fault mode can be completed utilizing standard fault character modes established by FCM algorithm, and calculating and comparing the similarity degree between this standard mode and sample. The arithmetic is applied to all kinds of typical faults diagnose in the diesel engine fuel system. Measuring results indicate that the precision of fault diagnosis is increased with the analysis of wavelet and FCM.     

PAHs formation mechanism during Combustion Process of Diesel Engines

Based on the diesel surrogate fuel (n-heptane and toluene), we develop a new kinetic mechanism of diesel surrogate fuel included polycyclic aromatic hydrocarbon (PAHs) formation and growth of up to five aromatic rings. The new mechanism included 153 species and 697 reactions. We compare it with various experimental data available in the literature including shock tube, n-heptane premixed flames and homogeneous charge compression ignition(HCCI) engine, and the results show the good performance for HCCI combustion prediction by this new mechanism. The presented mechanism can be used as the basis for further reductions and applied the combustion and emission simulation by coupling chemical reaction kinetics model with computational fluid dynamics model in internal combustion engines.     

Carbonyl Emission Influenced by Combustion Process of Diesel Engine

The bench test of diesel engine is conducted fueled with biodiesel, diesel and blending fuel, the changes of cylinder pressure with crank angle is also measured, combined with the measurement results of carbonyl emissions, the theoretical relationship between combustion process and carbonyl formation is analyzed. The results show that, combustion intermediates such as C7, C5, CO and C2H2 are produced in the fuel oxidation process during the premixed combustion phase. The diffusion combustion period extend with the increase of load, and it is the main stage of re-oxidation and decomposition for the intermediate products, the cylinder temperature and pressure increase with the increase of load, while the ignition delay period is shortened, the probability of oxidation and conversion for carbonyl pollutants improve because of the extended residence time in the high-temperature and high pressure region, the high exhaust temperature in high load is conducive to the re-oxidation of carbonyl emissions.     

分光光度法测定水中柴油的研究

为了探索一种检测水中柴油的简单、可靠而适用的测定方法,笔者通过向去离子水中添加柴油的回收率试验,研究利用紫外分光光度法测定水中柴油。本研究考查了柴油的最佳紫外吸收光谱条件、不同溶剂的提取效率、不同震荡时间的提取效果以及最佳的溶剂提取量等关键参数,结果表明：在最佳实验条件下,测定水溶液中的柴油回收率在90%~120%之间,平行间变异系数小于10%,回收率试验效果较好。     

A high pressure fuel injection system of a 4JB1 diesel engine

A fuel system evaluation method was introduced to select the proper high pressure injection system for diesel engines. Using this method, the second generation common rail system of BOSCH Company was selected for use in the 4JB1 diesel engine. Based on this common rail system, a fuel supplying model was built using AMESim. The model included a high pressure pump sub module, a pressure control valve sub module, an injectors sub module, and a connecting pipes sub module. Through model simulation, the influences of parameters (e.g., rail volume, high pressure pipe length and diameter) on pressure fluctuations and pressure building were studied. Rail pipe system parameters were selected based on simulation results. Experimental results show the rail pipe parameters could satisfy the needs of rapid pressure response and low pressure fluctuations for common rail diesel engines.     

EXPERMNTALRES6ACNONTACTICS OF INTEMGENTOPTIMIZATION FOR DIAGNOSIS TECHNOLOGYTODIESELENGINE

The breakdown model of diesel engine is conlnded and classified.The intelligentoptimization on tacties and mothed of diagnsis lechnology to diesel engine is discussed. The paper a-summes basic structure of expert system,analies relationship and property of each parameter to dieselengine,puts forward and discusses typical context tree,certainty factor, regulation and deloyment.The paper adopts a great deal of typieal parameter and breakdown.     

Research of the Ignition Timing System for Compressed Natural Gas Vehicle

Compared to bi-fuel engine,it uses completely CNG(Compressed nature gas) to replace diesel which can save more oil fuel than bi-fuel engine that reffited diesel engine into CNG engine. A 4102 diesel engine is refitted into CNG engine and a mechanical ignition timing system is designed by the method of gear and belt. The principles and the construction of the system is introduced and the characteristics of the design is analyzed. The system performed well and had good liability when run in a platform. Compared with the previous one, it kept higher dynamic character and emitted lower. It is a cheap one and can be use to reform the diesel engines.     

Artificial neural network approach for prediction of ammonia emission from field-applied manure and relative significance assessment of ammonia emission factors

This article presents a systematic method for enhancing the estimation accuracy of ammonia emission from field-applied manure and for assessing the relative significance of ammonia emission factors, using the feedforward-backpropagation artificial neural network (ANN) approach.

The multivariate linear regression (MLR) method well describes the ammonia emission tendency with the emission factor variation. However, ammonia emission from manure slurry is too complex to be captured in a linear regression model. This necessitates a model which can describe complex nonlinear effects between the ammonia emission variables such as soil and manure states, climate and agronomic factors. In the present study, a principle component analysis (PCA) based preprocessing and weight partitioning method (WPM) based postprocessing ANN approach (called the PWA approach) is proposed to account for the complex nonlinear effects.

The ammonia emission is predicted with precision by the 11 emission factors, using the nonlinear ANN approach. The relative importance among the 11 emission factors is identified using the elasticity analysis in the MLR method and using the WPM in the ANN approach. The relative significance obtained quantitatively by the PWA approach in the present study gives an excellent explanation of the most important processes controlling NH₃ emission.     

Kinetic characteristics of ignition process of diesel surrogate fuel

The purpose of this paper is to identify the effects of toluene and the toluene content which is at different initial temperatures on the ignition delay time of diesel surrogate fuel under homogeneous charge compression ignition (HCCI) engine condition. The CHEMKIN4.1 module (closed homogeneous batch reactor) is used with the constructed diesel surrogate fuel chemical kinetics model to simulate the constant volume. The results show that the ignition property is mainly characterized by n-heptane. The presence of the slowly oxidizing toluene in the surrogate fuel does not affect the auto-ignition time considerably. In addition,the influence of toluene content on the ignition delay time is significant only at low initial temperature. More ignition delayed combustion processes have been found when toluene content is increasing.     

利用大豆油制备生物柴油的技术研究

研究了大豆油在碱催化剂(KOH)的作用下与甲醇发生转脂化反应,制备生物柴油的工艺条件,并采用气相色谱法,测定了生物柴油中脂肪酸甲酯的成分及含量。探讨了醇油摩尔比、催化剂用量、反应温度和反应时间等工艺条件对生物柴油得率的影响。正交实验结果表明,最佳反应条件为:反应温度50℃,醇油摩尔比为6∶1,催化剂添加量为1.3%,反应时间为40min,在此反应条件下,生物柴油得率高达92%。     

亚麻木酚素对组织氧化损伤影响研究

研究了亚麻木酚素对红细胞自氧化溶血和肝匀浆脂质过氧化的抑制作用。结果表明,亚麻木酚素对红细胞氧化溶血、脂质过氧化具有明显的抑制作用。     

CVT刚性联接发动机曲轴轴系结构的扭振分析

因非道路车辆的特殊结构和成本限制，提出四缸柴油发动机中采用CVT刚性联接曲轴轴系结构。阐述了该新型结构的特征和工作原理，建立了四缸柴油发动机离合式曲轴计算模型和CVT刚性联接曲轴计算模型。通过曲轴前端实验，证明了所建模型和模型参数确定方法的正确性。求解所有计算模型，并对结果进行对比分析。结果表明，CVT刚性联接使曲轴轴系振动波动加大，减振器耗散能增加，各阶共振峰值对应转速低减。对曲轴各拐剪切应力幅度的影响不大，但有高转速工况降低而中低转速剪切应力幅值增加的普遍趋势，CVT端的扭振振幅和剪切应力较大些。综合研究得出结论：非道路车辆低速四缸柴油发动机可以采纳CVT刚性联接曲轴轴系结构。     

脂肪氧化产物丙二醛对牛肉色泽稳定性的影响

以脂肪氧化的标志性产物丙二醛(MDA)为对象,推理脂肪氧化对肉色稳定性影响的关系。结果表明,向肌红蛋白溶液添加MDA,对肌红蛋白的氧化无显著性影响(p>0.05);向牛肉糜中直接添加MDA,不会对线粒体活性、高铁肌红蛋白还原酶活力(MRA)以及牛肉糜红度a*值造成影响。脂肪氧化的产物MDA并不是造成肉色劣变的原因。脂肪氧化的产物促进肉色褐变方面的机理,还有待研究。     

欠发达地区农地利用碳排放时序特征及影响因素研究

农地碳排放研究对于区域农业可持续发展具有重要意义。笔者利用1996—2013年贵州省化肥、农药、农膜、农用柴油、翻耕、灌溉六大类碳源的相关数据,对贵州省18年间农地利用碳排放进行测算,并采用kaya恒等式对农地利用碳排放的影响因素进行分析。研究表明:(1)贵州省农地利用碳排放总量和碳排放强度均呈现持续上升的态势;(2)贵州省农地利用碳排放增速呈现波动的状态,且波动幅度较大;(3)化肥是最主要的碳排放源,其次为农膜和农用柴油;(4)生产效率因素、产业结构因素对贵州省农地利用碳排放具有抑制作用,经济水平、劳动力规模对农地利用碳排放具有促进作用。最后,本文对贵州省农地利用碳排放提出对策建议。     

MgO的添加量对CaO催化酯交换反应制备生物柴油的影响

采用浸渍法制备CaO/MgO固体碱催化剂,并应用于菜籽油与甲醇的酯交换反应制备生物柴油。考察了镁钙比对CaO/MgO催化活性的影响。试验表明,用质量分数22.6%的乙酸钙浸渍MgO,镁钙摩尔比为3～4时最接近等体积浸渍,镁钙摩尔比为1~2时为过量浸渍。镁钙摩尔比越低,催化剂活性越高,但镁钙摩尔比低于3时,催化剂活性组分分布不均匀,且活性增加不明显。所以最佳镁钙摩尔比为3～4。     

Study of Direct Methanol Fuel Cell for Portable Application

A technique of fabrication of air electrode for direct methanol fuel cells (DMFC) is proposed. The investigated air electrode is free of Teflon- containing and with ultra- thin catalyst layer. Catalysts PtRu/C for methanol electroxidation is electrochemically deposited on a Nafion- bonded carbon electrode. A concept, that is, methanol is oxidized at a relatively high potential, is proposed. Such a fabricated DMFC is characterized with a high utilization of noble metals and basically eliminating CO poisoning in operation.     

THE PROGRESS OF SPECTROELLTPSOMETRIC INVESTIGATION FOR ANALYZING ELECTROCHEMICAL REACTIONS

This paper describes the initial idea of building up a new approach of spectroscopic ellipsometry for studying electrochemieal reaction from some of the author's experimental results on ellipsometry. The results which have proved the possibility of this idea is also presented. The study on an odic oxidation of iron and the oxidation and reduction processes of polyaililine film by ellipsometry with different wavelength show that the ellipsometric spectroscopy might be a new method for analyzing electrochemical reactions.     

Research and Experiment on Mixed Liquor of Orbal Oxidation Ditch

This experiment is one of the improved types of Orbal oxidation ditch technologies belonging to the sewage treatment engineering project to be carried out at the small town in western China supported by the Holland Grant Project.The survey for similar Orbal oxidation ditch was performed on-the-spot for safety of engineering design.The experiment individually focused on the velocity distribution of concentration ellipse shape represented in oxidation ditches existed in sewage treatment plants,and confirmed the rationality of aeration and the submersed flow driver power designed.The result shows: Firstly,for such oxidation ditch,it is easy to cause sediment resulted from complex waterpower of crook,and affect blend condition.Secondly,the sediment is prevalent,especially in some places.Finally,the design power of aeration and submersed flow driver are insufficient.