船用发动机有害排放气体的评价及处理研究--燃料性质和输出轴扭矩变化对发动机排放特性的影响

为了评价船用发动机有害气体的排放,本文从燃料的性质着手,较为详细地对不同性质的１３种燃 料进行了研究,并在一台中型四冲程船用柴油机上进行了试验,测定了各种有害排气的浓度、发动机的 性能和燃烧特性,对燃料的性质与排放之间的相关性进行了探讨。进一步调查研究了柴油机运转工况的 不同及输出轴扭矩的变化对ＮＯｘ排放的影响。由试验结果可知：对于周期性输出扭矩的变化,ＮＯｘ的排 放也发生周期性的变化。但是,柴油机在高输出区域运转时,随着扭矩增加所换算的ＮＯｘ浓度呈减小的 趋势;反之,在低输出区域运转时,呈增加的趋势;输出扭矩周期性变化时的ＮＯｘ。的浓度可以用与其相 对应的平均负荷状态的ＮＯｘ浓度处理。     

原子吸收光谱法一灯多用技术在分析测试中的实验研究

文中对用Zn空心阴极灯作光源测定Cu与Cu空心阴极灯测定Cu,用Cd空心阴极灯作光源测定Ag与Ag空心阴极灯测定Ag,用Ca空心阴极灯作光源测定Mg与Mg空心阴极灯测定Mg,进行了比较实验研究。通过实验发现,可以用Zn空心阴极灯代替Cu空心阴极灯测定Cu,用Cd空心阴极灯代替Ag空心阴极灯测定Ag,用Ca空心阴极灯代替Mg空心阴极灯测定Mg;其测定检出限相近、精密度高。用国家地球化学标准样品GBW0 7401(GSS-1)、GBW0 7311(GSD-11)进行验证,其准确度较好。     

胶东招平断裂带金矿成矿指示元素特征及找矿应用

对招平断裂带上的大尹格庄、夏甸、山后、大磨曲家等金矿进行了矿体原生晕测量,分析了Au、Ag、Cu、Pb、Zn、As、Sb、Bi、Mo、Hg 等10 种元素,统计了微量元素含量和相关系数。与金相关的元素中,As 在每个矿床均出现;Ag、Pb、Cu、Sb 在大部分矿床出现;Mo、Bi、Zn 只在个别矿床出现。前缘晕元素As是最好的成矿指示元素,可以用As 的含量结合其他元素异常开展地球化学深部预测。划分了As、Au 元素强弱异常标准,As 元素含量大于4×10-6 为强异常,1.5×10-6~4×10-6 为中等异常,小于1.5×10-6 为弱异常;金元素含量大于35×10-9 为强异常,10×10-9~35×10-9 为中等异常,小于10×10-9 为弱异常。总结了深部地球化学预测的3 种准则,经矿区实际验证预测效果较好。     

On listing,sampling, and counting the chordal graphs with edge constraints

We discuss the problems to list, sample, and count the chordal graphs with edge constraints. The objects we look at are chordal graphs sandwiched by a given pair of graphs where we assume that at least one of the input graphs is chordal. The setting is a natural generalization of chordal completions and deletions. For the listing problem, we give an efficient algorithm running in polynomial time per output with polynomial space. As for the sampling problem, we give two clues that indicate that a random sampling is not easy. The first clue is that we show #P-completeness results for counting problems. The second clue is that we give an instance for which a natural Markov chain suffers from an exponential mixing time. These results provide a unified viewpoint from algorithms’ theory to problems arising from various areas such as statistics, data mining, and numerical computation.     

Effects of ferric chloride on thermal degradation of γ‐oryzanol and oxidation of rice bran oil

The kinetics of γ‐oryzanol degradation in antioxidant‐stripped rice bran oil were investigated at 180°C for 50 h. Ferric chloride was added to the oil at different concentrations (0, 2.5, 5.0, and 7.5 mg/kg‐oil) to determine the degradation reaction rate of γ‐oryzanol and the extent of lipid oxidation (peroxide value and p‐anisidine value). It was found that the losses of γ‐oryzanol and its four components (cycloartenyl ferulate, 24‐methylene cycloartanyl ferulate, campesteryl ferulate, and β‐sitosteryl ferulate) could be described by a first‐order kinetics model. The degradation rate constant, k, linearly increased (p < 0.05) with the ferric chloride concentration, and increased about 1.5 times when 7.5 mg/kg‐oil ferric chloride was added. Ferric chloride addition also accelerated the lipid oxidation of rice bran oil significantly (p < 0.05). Practical applications: This paper describes the kinetic analysis of the degradation of γ‐oryzanol, a major phytochemical in rice bran oil, at its frying temperature. The results indicated that iron in the form of ferric chloride accelerated both the degradation of γ‐oryzanol and lipid oxidation.     

Morphology and Thermal Properties of Poly[bis(β-phenoxyethoxy)phosphazene]

The structure and thermal properties of poly[bis(-phenoxyethoxy)phosphazene)] (PBPEP) newly synthesized by us were investigated. The crystallization from the melt, the volumetric relaxation in the amorphous phase in the upper vicinity of the glass transition temperature (T _g) and the enthalpy of relaxation of the glass in the lower vicinity of the T _g were shown to be very slow. These slow rates may be related to the low chain mobility due to the bulky side chain. Two kinds of crystal forms, called and forms were found in the melt-crystallized sample. These forms were clearly seen as individual types of spherulites by optical microscopy. The melting temperature of these crystals were analyzed by the Hoffmann–Weeks plot. The so-called T(1) transition that had often been detected in many crystalline polyphosphazenes as the transition from the crystal phase to the mesophase was not observed by x-ray diffraction at elevated temperatures.     

Manufacturing Silicon Carbide Microrotors by Reactive Hot Isostatic Pressing within Micromachined Silicon Molds

A novel ceramic microfabrication process—based on the idea of silicon carbide (SiC) reaction sintering within a micromachined silicon mold—has been developed to produce a SiC microroter for miniaturized gas turbines. The new process involves the micromachining of silicon molds; filling the molds with powder mixtures of α-SiC, graphite, and phenol resin; bonding the molds with an adhesive; reaction sintering by hot isostatic pressing (HIP); and the releasing of a reaction-sintered workpiece from the mold by wet etching. Using this process, we have successfully fabricated SiC microrotors with a diameter of 5 mm, whose complicated geometry was well transferred from the negative shape of the micromachined silicon mold. The reaction-HIPed SiC ceramics within Si molds showed reasonably good mechanical properties, which are comparable to those of the commercialized reaction-sintered SiC ceramics.     

Prediction of particle charging in a dilute pneumatic conveying system

When particles are transported in pipelines, they acquire electrostatic charges as they come into contact with the pipe wall. Charged particles can cause problems such as particle agglomeration, blockage, and explosion. Understanding the particle charge can help to prevent these issues. This study investigates a technique for predicting the particle charge in a straight pipe of any given length, as well as the pipe length at which electrostatic equilibrium occurs, through experimentation in a short 1‐m pipe section. Experimentation with five different types of particles and four pipe wall materials at longer pipe lengths were used to validate the technique. This predictive technique is applicable to a range of particle shapes and sizes under the restriction that charge transfer is due to impact charging. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2308–2316, 2013