Characterization of Particulate Matter from Direct Injected Gasoline Engines

The reactivity and reaction kinetics of particulate matter (PM) from direct injected gasoline (GDI) engines has been studied by O₂ and NO₂ based temperature programmed and isothermal step-response experiments, and the PM nano-structure has been characterized using HRTEM. The reactivity of the PM samples collected in filters during on-road driving was found to increase in the following order: Printex U < diesel < gasoline PI ≈ gasoline DI < ethanol for O₂ based combustion. The activation energies for O₂ and NO₂ based oxidation of PM collected from a GDI engine in an engine bench set-up was estimated to 146 and 71 kJ/mol respectively, which is comparable to corresponding values reported for diesel and model soot. Similar nano-structure features (crystallites plane dimensions, curvature and relative orientation) as observed for diesel soot were observed for gasoline PM.     

生物柴油掺烧甲醇对柴油机污染物影响研究

在186FA柴油机上,进行了燃用生物柴油和甲醇/生物柴油混合燃料的排放试验。研究结果表明,与燃用生物柴油相比,BM15在Pe=1.57 kW时CO升高279.1%,HC排放升高96.3%;随着混合燃料中甲醇浓度增加,NOx排放减少,标定转速满负荷BM15的NOx排放降低42.7%;低负荷时排气烟度相差不大,均不超过0.1 BSU,高负荷时BM15排气烟度降低51.2%。     

Comparison of Strategies for the Measurement of Mass Emissions from Diesel Engines Emitting Ultra-Low Levels of Particulate Matter

Regulatory methods for the measurement of particulate matter (PM) mass emissions have traditionally been gravimetric. Modern diesel engines equipped with aftertreatment systems, especially Diesel Particulate Filters (DPFs), however, emit much smaller amounts of particulate matter as compared to traditional diesel engines and emit particulate matter with variable compositions. These changes have led to difficulties in measuring PM emissions rates from modern diesel engines using gravimetric methods. Issues associated with diesel PM mass measurement, such as the semi-volatile nature of PM, the interactions with components in the dilution air such as water and ammonia, and the possibility of sampling artifacts, have counteracted a singular focus on mass measurements. These inherent problems may warrant some alternative approaches to characterizing emissions, using methods related to mass and impacts of emissions that can be more accurately defined. The present study provides a comparison and relative precision of several alternative mass measurement methods employed to measure the mass emissions of particulate matter from diesel engines with low and ultra-low levels of emissions. The methods of measurement reviewed in this study include two gravimetrically based methods, a chemically reconstructed mass method, and an integrated particle size distribution (IPSD) method. The mass measurements were consistent at low emission levels but the chemical speciation and IPSD methods achieved closer agreement and were more precise at ultra-low emission levels. Although mass measurement is a NIST-traceable quantity, alternative methods may present a new paradigm that better characterizes engine emissions in an atmospherically relevant manner.     

汽车尾气净化催化剂的研究

为了迎接越来越严格的汽车尾气排放标准的挑战，催化剂科研工作者必须与产业界合作，着重解决该领域扣关键技术，开发新型汽车尾气净沦稀土催化剂，以取代贵金属催化剂，并提高催化剂使用性能。     

Experimental Study on Particulate Emissions of a Methanol Fumigated Diesel Engine Equipped with Diesel Oxidation Catalyst

In this article, the effects of fumigation methanol, diesel oxidation catalyst, and engine operation parameters (engine load and engine speed) on diesel smoke opacity, particulate mass concentration, particulate number concentration and the soluble organic fraction (SOF) in the particulate were investigated at certain selected operation conditions. Experiments were performed on a 4-cylinder direct injection diesel engine operating at three engine speeds and three loads for each engine speed. For each engine speed, there was a decrease of smoke opacity with increase in the level of fumigation methanol. The reduction was particularly obvious at the high engine load but was not significant at the low and medium engine loads. For all test conditions, fumigation methanol could effectively reduce the particulate mass and number concentrations. However, fumigation methanol increased the fraction of SOF in the particles. The DOC could further reduce the particulate mass and number concentrations as well as the fraction of SOF in the particles when the exhaust gas temperature was sufficiently high.     

Advances in the Development of Filterless Soot Deposition Systems for the Continuous Removal of Diesel Particulate Matter

A model catalytic converter system has been developed to investigate and characterize novel catalyst structures for filterless diesel particulate matter deposition and oxidation in modern heavy duty vehicle diesel engine exhaust systems. The particulate traps are designed for low exhaust gas back pressures and to avoid the clogging effects observed in ceramic filters. In experiments under realistic flow conditions deposition efficiencies of up to 70% have been achieved for submicrometer particles in stacks of corrugated stainless steel foil with microsphere surface coating. The model catalytic converter system is also used to study the reaction kinetics of soot oxidation and volatilization by oxygen and nitrogen oxides under a wide range of reaction conditions, for real diesel engine soot, different model soot substances, and different types of converter surfaces.     

Modeling of Creep Behavior of Particulate Composites with Focus on Interfacial Adhesion Effect

Evaluation of creep compliance of particulate composites using empirical models always provides parameters depending on initial stress and material composition. The effort spent to connect model parameters with physical properties has not resulted in success yet. Further, during the creep, delamination between matrix and filler may occur depending on time and initial stress, reducing an interface adhesion and load transfer to filler particles. In this paper, the creep compliance curves of glass beads reinforced poly(butylene terephthalate) composites were fitted with Burgers and Findley models providing different sets of time-dependent model parameters for each initial stress. Despite the finding that the Findley model performs well in a primary creep, the Burgers model is more suitable if secondary creep comes into play; they allow only for a qualitative prediction of creep behavior because the interface adhesion and its time dependency is an implicit, hidden parameter. As Young’s modulus is a parameter of these models (and the majority of other creep models), it was selected to be introduced as a filler content-dependent parameter with the help of the cube in cube elementary volume approach of Paul. The analysis led to the time-dependent creep compliance that depends only on the time-dependent creep of the matrix and the normalized particle distance (or the filler volume content), and it allowed accounting for the adhesion effect. Comparison with the experimental data confirmed that the elementary volume-based creep compliance function can be used to predict the realistic creep behavior of particulate composites.     

Effective Density and Volatility of Particles Emitted from Gasoline Direct Injection Vehicles and Implications for Particle Mass Measurement

The effective density and volatility of particulate emissions from five gasoline direct injection (GDI) passenger vehicles were measured using a tandem differential mobility analyzer (DMA) and centrifugal particle mass analyzer (CPMA) system. The measurements were conducted on a chassis dynamometer at three steady-state operating conditions. A thermodenuder was employed to find the volatility and mixing state of the particles as well as the effective density of nascent and non-volatile particles (defined as particle phase remaining after denuding at 200°C). The mass–mobility exponent ranged between 2.4 and 2.7 for nascent (or undenuded) particles and between 2.5 and 2.7 for non-volatile particles; higher than typical diesel soot. The effective density function was 4278d_m^?0.438 ± 76.3 kg/m³ (for mobility diameter, d_m, in nm) for nascent particles and 3215d_m^?0.395 ± 37.9 kg/m³ for non-volatile particles. The effective density functions of the non-volatile particles were fairly similar for the conditions studied. The uncertainty in using the effective density and mixing state data to determine the mass concentration of the aerosol by integrating mobility size distributions was examined. The uncertainty in mass concentration is minimized when only the non-volatile component is measured. However, the uncertainty in the mass concentration increases substantially if nascent particles are measured due to uncertainties in the particle mixing state and their associated effective densities. Furthermore, transient vehicle operation (cold-starts, accelerations, and decelerations) would likely change the mixing state of the exhaust particles suggesting it is difficult to accurately measure the mass concentration of undenuded GDI exhaust particulate using integrated size distribution methods.

Copyright 2015 American Association for Aerosol Research     

注塑机驱动系统模糊协调控制研究

提出了一种基于泵自吸能力下降拐点的模糊协调控制方法,根据变量液压泵的最低转速设计了切换器。依据实际系统的特点,选用正态函数变换得到S型函数,采用误差论域点离散的方法来处理所选择的隶属函数,确定不同误差域控制器的作用强度。由于系统自身的参数和负载参数的不确定性,采用模糊控制的方法,解决模型不好建立的问题,取得了良好的动态特性。仿真和实验表明,此方法能够解决注塑机驱动系统出现的低速特性差的问题。     

Synthesis and Pharmacological In Vitro Investigations of Novel Shikonin Derivatives with a Special Focus on Cyclopropane Bearing Derivatives

Melanoma is the deadliest form of skin cancer and accounts for about three quarters of all skin cancer deaths. Especially at an advanced stage, its treatment is challenging, and survival rates are very low. In previous studies, we showed that the constituents of the roots of Onosma paniculata as well as a synthetic derivative of the most active constituent showed promising results in metastatic melanoma cell lines. In the current study, we address the question whether we can generate further derivatives with optimized activity by synthesis. Therefore, we prepared 31, mainly novel shikonin derivatives and screened them in different melanoma cell lines (WM9, WM164, and MUG-Mel2 cells) using the XTT viability assay. We identified (R)-1-(1,4-dihydro-5,8-dihydroxy-1,4-dioxonaphthalen-2-yl)-4-methylpent-3-enyl 2-cyclopropyl-2-oxoacetate as a novel derivative with even higher activity. Furthermore, pharmacological investigations including the ApoToxGlo^TM Triplex assay, LDH assay, and cell cycle measurements revealed that this compound induced apoptosis and reduced cells in the G1 phase accompanied by an increase of cells in the G2/M phase. Moreover, it showed hardly any effects on the cell membrane integrity. However, it also exhibited cytotoxicity against non-tumorigenic cells. Nevertheless, in summary, we could show that shikonin derivatives might be promising drug leads in the treatment of melanoma.     

重视碳一化学开发丙烯及汽柴油合成技术

论述了天然气和煤炭在替代石油资源中作为碳一化学重要原料的意义，分别介绍了已工业化的和正在开发的各项碳一化学工程化技术，并强调应重点开发合成丙烯和汽柴油的几项技术。     

连接管自动脱螺纹注塑模具设计

根据连接管的结构特点,采用“斜导柱+滑块+定位滚珠”的侧向抽芯机构和“马达+链条+链轮”的自动脱螺纹机构设计了一副注塑模具。重点分析和研究了模具的浇注系统、成型零件、脱模系统和自动脱螺纹机构、侧向抽芯机构、温度控制系统,并对自动脱螺纹机构设计要点进行了总结。经生产证明,成型塑件完全符合设计要求。     

煤焦直接还原法脱除NO_x几种因素对脱除率的影响

在实验室模拟工业烟气组成将烟气通入固定床反应器与改性煤焦反应,用烟气分析仪测量NOx的含量来对比脱硝效率。实验表明:反应的最佳温度范围是450～550℃;改性煤焦的粒径在1～3 mm较为适宜;SO2、H2O的存在对反应有一定的影响;随着气速的增大,NO脱除率也随之降低,但是趋势不是很明显。实验初步认为煤焦直接还原法脱硝具有较高的脱硝效率,是一种新颖的技术思路。     

基于低温等离子体协同催化脱除氮氧化物和碳烟颗粒的研究

文章介绍了等离子体净化柴油机尾气技术的机理和研究状况。研究表明电晕放电和介质阻挡放电等离子体净化柴油机尾气有着能耗过高的缺陷,在应用中不得不结合催化剂同时使用。由于等离子体放电能够产生大量的自由基,能够使柴油机颗粒物PM在较低的排气温度下得到氧化燃烧。同时等离子体常与选择性催化还原技术相结合,作为辅助手段以提升系统去除NOX的效率和提高其选择性[1]。研究发现等离子体协同催化脱除氮氧化物和PM技术对解决柴油车尾气污染问题有着重要的意义。     

New Design of a Ceramic Filter for Diesel Emission Control Applications

Diesel particulate filters (DPF) made from an advanced ceramic material (ACM) based on mullite have demonstrated high filtration efficiency, low-pressure drop, high-temperature handling capability, and excellent mechanical integrity at a porosity of 60% or higher. Due to the ability to control microstructure, total porosity, and particle size distribution, Dow's acicular mullite can be tailored to meet requirements for deep bed filtration and fine particles emission control. In addition, the ACM DPF is suitable for catalyzed applications and it can retain its performance with a broad range of catalysts and over a wide range of catalyst loadings. This study describes a material selected for a DPF design that meets current diesel particulate emission control requirements as well as a four-way NO _x control system.     

一类不确定多时滞系统的鲁棒容错控制研究

讨论一类线性不确定多时滞系统的鲁棒容错控制问题.基于Lyapunov稳定性理论和线性矩阵不等式方法（LMI）,针对一类参数有界不确定多时滞系统,给出了状态反馈鲁棒容错控制器设计方法,并且利用该方法得到的闭环控制系统,不仅在执行器失效情况下具有渐进稳定性,对参数不确定也具有良好的鲁棒性.最后,应用设计实例及仿真结果验证该设计方法的可靠性和有效性.     

基于调度与控制协同设计的网络控制系统研究

分析网络控制系统中调度与控制的关系,对调度与控制协同设计的研究现状做了综述,从动态调度和静态调度角度总结了目前这一领域的研究进展,并提出了考虑调度与控制协同设计的反馈控制调度基本结构.     

茶饮杯螺旋底盖侧抽芯热流道注塑模设计

基于茶饮分离杯螺旋底盖的结构及工艺要求,设计了外侧抽芯热流道注塑模。根据该模具的设计过程,侧重对模具的工作原理、成型零件、热流道浇注系统、外侧抽芯机构、顶出机构及冷却系统进行设计计算。 实际生产表明,该模具结构合理、生产效率高、产品质量优。     

Preparation of a New Adsorbent Based on Wood Pulp for the Removal of Direct Blue 2 from Aqueous Solutions

Wood pulp was used as starting material for preparation of a new adsorbent for removal of Direct Blue (DB 2) from aqueous solutions. The adsorbent material was prepared by the reaction of wood pulp (WP) with epichlorohydrin and dimethylamine in the presence of pyridine and N,N-dimethylformamide (DMF). The so obtained adsorbent was called with wood pulp adsorbent (WPA). The adsorption of DB 2 onto WPA was investigated. The adsorption data show that the maximum adsorption capacity, Q_max, of DB 2 onto WPA is 102.04 mg/g. The adsorption data also show that the adsorption of DB 2 onto WPA obeys Langmuir and Freundlich isotherms.     

Removal of Residual Dissolved Ozone with Manganese Dioxide for Process Control with UV254

Ozonation is one of the most promising options to remove organic micropollutants (OMP) from wastewater treatment plant effluents. For an economic operation and in order to avoid formation of bromate, the ozone dose has to be adjusted in real-time due to the strongly varying effluent quality. The reduction of UV absorption at 254 nm (?UV₂₅₄) is a useful surrogate parameter for OMP removals. Unfortunately dissolved ozone also absorbs UV at 254 nm and therefore might disturb a ?UV₂₅₄-based process control. A fixed bed of manganese dioxide granules was found to efficiently remove residual ozone.