新形势下铁路客运市场分析及发展策略

文章分析了我国旅客运输市场的需求及发展趋势，论述了经济发展和城市化进程对旅客运输需求总量及旅客运输市场的影响。通过对铁路客运市场现状及原因分析，提出了新形势下铁路客运的市场定位及铁路客运的发展策略。     

Target recognition based on modified combination rule

1 .INTRODUCTIONThe evidence theory also known as D-S theory isan approach handling of uncertainty .It was firstput forward by Dempster A.P.in 1968 and thenmodified by his student G. Shafer in 1971[1 ~2].This theoryis the extension of Bayesiantheory andfurthermore it can deal with uncertainty caused bythe inaccurate or unknown of knowledge . So ,ithas been extremely wide used in data fusion field.However ,everything has its own weakness .It isinvalid when dealing with highly conflict e…     

American continuous-installment options of barrier type

This paper analyzes and values an American barrier option with continuous payment plan written on a dividend paying asset under the classical Black-Scholes model.The integral representation of the initial premium along with the delta hedge parameter for an American continuous-installment down-and-out call option are obtained by using the decomposition technique.This offers a system of nonlinear integral equations for determining the optimal exercise and stopping boundaries,which can be utilized to approximate the option price and delta hedge parameter.The implementation is based on discretizing the quadrature formula in the system of equations and using the Newton-Raphson method to compute the two optimal boundaries at each time points.Numerical results are provided to illustrate the computational accuracy and the effects on the initial premium and optimal boundaries with respect to barrier.     

Extraction and separation of nickel and cobalt from saprolite laterite ore by microwave-assisted hydrothermal leaching and chemical deposition

Extraction and separation of nickel and cobalt from saprolite laterite ore were studied by using a method of microwave-assisted hydrothermal leaching and chemical deposition. The effects of leaching temperature and time on the extraction efficiencies of Ni2+ and Co2+ were investigated in detail under microwave conditions. It is shown that the extraction efficiencies of Ni2+ and Co2+ from the ore pre-roasted at 300℃ for 5 h were 89.19% and 61.89% when the leaching temperature and time were about 70℃ and 60 min, respectively. For the separation process of Ni and Co, the separation of main chemical components was performed by adjusting the pH values of sulfuric leaching solutions using a NaOH solution based on the different pH values of precipitation for metal hydroxides. The final separation efficiencies of Ni and Co were 77.29% and 65.87%, respectively. Furthermore, the separation efficiencies of Fe of 95.36% and Mg of 92.2% were also achieved at the same time.     

燃煤厂烟气脱硫废水处理新策略及其作用机制

为了探究颗粒污泥对燃煤厂烟气脱硫废水营养型污染物的去除及微生物种群结构的变化特征,建立序批式厌氧/好氧反应器,以预处理后的燃煤厂烟气脱硫废水为研究对象,分析了污泥颗粒化进程中污泥特征,营养型污染去除及微生物群落结构的演变规律。结果表明污泥颗粒化进程中污泥沉降指数（SVI）显著下降,污泥中生物量显著升高,在120 d时,SVI下降至62 mL/g,混合液总悬浮固体（MLTSS）升高至7.1 g/L。此外颗粒污泥胞外聚合物中蛋白质（PN）显著提高,PN/多糖（PS）升高至2.71-2.74。在稳定运行期,颗粒污泥对COD,NH4+-N及总磷(TP)去除效率分别高达89.25-89.56%,93.4%和73.2%。微生物群落结构演变揭示污泥颗粒化进程提高Comamonadaceae及Pseudomonadaceae的相对丰度,从而提高脱氮除磷效率。     

Influence of gangue existing states in iron ores on the formation and flow of liquid phase during sintering

Gangue existing states largely affect the high-temperature characteristics of iron ores. Using a micro-sintering method and scanning electron microscopy, the effects of gangue content, gangue type, and gangue size on the assimilation characteristics and fluidity of liquid phase of five different iron ores were analyzed in this study. Next, the mechanism based on the reaction between gangues and sintering materials was unraveled. The results show that, as the SiO₂ levels increase in the iron ores, the lowest assimilation temperature (LAT) decreases, whereas the index of fluidity of liquid phase (IFL) increases. Below 1.5wt%, Al₂O₃ benefits the assimilation reaction, but higher concentrations proved detrimental. Larger quartz particles increase the SiO₂ levels at the local reaction interface between the iron ore and CaO, thereby reducing the LAT. Quartz-gibbsite is more conductive to assimilation than kaolin. Quartz-gibbsite and kaolin gangues encourage the formation of liquid-phase low-Al₂O₃-SFCA with high IFL and high-Al₂O₃-SFCA with low IFL, respectively.     

Influencing factor of sinter body strength and its effects on iron ore sintering indexes

Sinter body strength, which reflects the strength of sinter, plays an important role in the improvement of sinter. In this study, the sinter body strengths of iron ores were measured using a microsintering method. The relationship between the chemical composition and sinter body strength was discussed. Moreover, sinter-pot tests were performed. The effects of sinter body strength on the sintering indexes were then elucidated, and the bottom limit of sinter body strength of blending ores was confirmed. In the results, the compressive strengths (CSs) of iron ores are observed to decrease with the increasing of the contents of loss on ignition (LOI), SiO₂, and Al₂O₃; however, LOI of less than 3wt% does not substantially influence the CSs of fine ores. In the case of similar mineral composition, the porosity, in particular, the ratio between the number of large pores and the total number of pores, strongly influences the sinter body strength. With an increase of the blending-ore CSs used in sinter-pot tests, the yield, productivity, and tumbler strength increase, and the solid fuel consumption decreases. The CSs of the blending ores only slightly affect the sintering time. The CS bottom limit of the blending ores is 310 N. When the CSs of the blending ores increase by 10%, the yield, productivity, and tumbler index increase by 1.9%, 2.8%, and 2.0%, respectively, and the solid fuel consumption decreases by 1.9%.     

毛细管节流制冷装置内藏式冷凝器动态特性研究

根据分布参数、参数间定量耦合及动态的观点,用微元法探讨了毛细管节流制冷装置中内藏式冷凝器的动态特性数学模型,并对该类冷凝器的静态特性与动态特性进行了初步分析,提出了该类冷凝器优化及强化设计的方向.     

间冷式冰箱箱体模型研究

间冷式电冰箱箱体结构中存在流动换热的结构，这一特点决定了该类电冰箱箱体模型的建立与求解有别于直冷式，通过结构分析，提出简化边界条件的处理方法，并采用ｚ传递系数求解空气循环冷却系统的动态换热。模型的计算结果与针对性的实验结果吻合较好，为间冷式电冰箱的系统动态仿真奠定了基础。