Experimental Analysis of Construction Time Space Effect for Large Span and Flat Multi Arch Tunnel

For the large span and flat, together with the interaction effect of construction and disturbance of surrounding rock, the mechanical of large span and flat multi arch tunnel is very complicated, and the time space effect is different from that of two lane multi arch tunnel or separated tunnel. Adopting the “CTSSSRH”, the 3 D dynamic process of the tunnel construction was simulated. Analyzing the rule of surrounding rock displacement and stress with excavation, the time space effect of large span and flat multi arch tunnel was proposed.     

Simplifying and validating the model of wet flue gas desulphurization spray tower for 660MW units

The wet limestone gypsum flue gas desulphurization system for 660 MW units of a thermal power plant is taken as the object, based on the study of the mass transfer between the gas phase and the liquid phase、chemical reaction mechanism in desulphurization tower and reasonable simplified hypothesis, the turbulent mathematical model of the spray type tower is developed by the methods of concentration of parameters and module modeling. The model is validated by the test of stable state and the turbulent experiments, which can be used as the basis for developing the real training simulation model of the desulphurization system.     

The Effect of Slabs on the Failure Mode of Reinforced Concrete Frame Structures

A majority of reinforced concrete frame structure failure patterns resulting from the May 12, 2008 earthquake in Wenchuan County, P. R. China were analyzed. It was found that the main failure mode of frame works was “strong beam, weak column”, which conflicts with the design criteria of “strong column, weak beam”. The cause of this failure pattern was analyzed. A new concept is put forward that should be considered in design work. The over strength caused by slabs connected monolithically to the beams is analyzed. The joint types, transverse beam stiffness and lateral drift influence the reinforcing effect of the sla, Moreover, a reinforced concrete frame model was simulated using the program ABAQUS. The slab reinforcement stress distributions at different lateral drifts were analyzed and the effective flange width value proposed.     

Maximum tree method based aspect mining method

By means of discovering crosscutting concerns from legacy systems, aspect mining intends to help migrate the systems to an aspect oriented design. An improved method based on maximum tree method for aspect mining is presented. The method uses aspect ideas to capture the runtime method call information by mining crosscutting concerns from dynamic behaviors, and then constructs a method call relationship data matrix. Based on fuzzy similarity relation theory, by introducing the similarity, an object similarity matrix is constructed, and the maximum tree method is used to identify the crosscutting concerns in the system. The method can provide a basis for system’s software reconstruction and reusability. An experiment is conducted to verify the validity of the method. Compared with the existing typical mining methods, the method shows the virtue of clear implementation and high efficiency.     

Dynamic analysis and optimization of gear trains in a megawatt level wind turbine

Through coupling vibration analysis of the transmission system of a 1.5 MW wind turbine gearbox, a torsional vibration model of a gear drive system in wind turbines is established. The fourth order Runge Kutta integration method is applied to calculate the dynamic response of a gear system caused by wind loads, time varying meshing stiffness, and system damping. The harmonic balance method is used to find the analytic solution. Based on the solution, a mathematical model for optimum gear system design is established. The model aims at minimizing the vibration acceleration of the planet gear and the total mass of the gear transmission system. The optimization toolbox in MATLAB program is adopted to obtain the optimal solution. A calculated example shows that the primary natural frequency of the gear system has been raised, the dynamic properties of the gear train have been improved remarkably, and the total mass of the gear train has been decreased.     

北京山区不同林分类型土壤肥力的研究

为探讨山地森林土壤酶活性与土壤理化性质的关系,对北京延庆山区6种植被类型下不同层次土壤的脲酶、蛋白酶、转化酶、过氧化氢酶、多酚氧化酶的活性及其与土壤理化性质之间的关系进行研究。结果表明:在各种林分类型之间所测土壤理化性质和土壤酶指标有显著性差异,并且随着土层的加深,均表现出不断减小的趋势。蔗糖酶、脲酶、蛋白酶、过氧化氢酶4种酶活性在不同林分类型中均表现出阔叶林优于针叶林,而多酚氧化酶活性却表现出相反的趋势。所测5种酶活性在6种林分类型A层表现出聚集分布,以脲酶最具代表性。相关分析表明:有机质、全氮、碱解氮、速效钾与所测5种酶活性呈现出不同程度的正显著相关,而有效磷与各种所测酶活性均呈负相关。运用主成分分析可知,土壤酶在第1、2主成分中比重较大,对外界环境变化比较敏感,结合相关分析认为,碱解氮与脲酶可以作为该地区土壤质量评价的首选指标。      

水分胁迫下增施氮、磷对刺槐无性系苗木光合特性的影响

通过对两个刺槐无性系苗木在光照培养箱内进行盆栽,采用正交试验设计的方法,研究不同水分胁迫水平下增施氮磷对两个刺槐无性系苗木光合特性的影响。对光合光响应曲线、最大净光合速率、光饱和点、光补偿点和叶绿素含量进行分析,结果表明:随干旱程度加深,干旱前期氮磷交互作用对刺槐叶片光饱和点和光补偿点影响显著,干旱后期差异不显著。比较两个刺槐无性系苗木的光合特性得出,L1（鲁刺一号）比W1（皖刺一号）更为耐旱。      

广西桉树林取代马尾松林对植物多样性的影响

对广西钦州市马尾松林和巨尾桉人工林的植物多样性开展研究,旨在阐明桉树林取代马尾松林对植物多样性和植物功能群的影响,促进对桉树人工林的科学认知。研究表明,采伐马尾松林种植桉树后10年,在1 800 m2样地内,桉树林的物种数为95～98种（木本植物50种,藤本17～19种,草本24～28种）,而马尾松林为63～88种（木本植物32～48种,藤本13～24种,草本16种）,两类林分的木本、藤本和总物种数差异不显著（P为0.237～0.937）,而草本植物差异显著（P=0.038）,表明桉树林取代马尾松林将显著增加草本植物的物种丰富度。桉树林取代马尾松林对铁芒萁有显著的负效应,重要值减少50%（P=0.077）,而对五节芒（P=0.057）和东方乌毛蕨（P=0.079）有显著的正效应,重要值提高0.85～3.76倍。桉树林和马尾松林木本植物的Shannon Wiener指数(H′)、Simpson指数(D)和均匀度指数(Jsw)差异不显著（P为0.299～0.957）,而草本植物的H′、D和Jsw差异极显著（P≤0.002）。桉树林取代马尾松林对群落的物种多样性和功能群具有显著的影响,然而,桉树人工林建立过程中采取的采伐、炼山、整地、施肥等措施是导致群落物种多样性和功能群变化的主要原因。      

福建省山地坡面风景游憩林单因素美景度评价研究

风景游憩林美景度评价结果可用于指导风景游憩林的构建,也可为建立风景游憩林美学特征和审美态度的心理物理模型积累基础研究数据。采用美景度评判法（scenic beauty estimation,SBE）对福建省山地坡面风景游憩林进行分析,结果表明:风景游憩林的质地、冠形的可辨度、统一度和对比度、斑块边界线、树种组成及年龄结构、群落垂直结构、混交方式等对森林风景的美景度均有一定影响。并根据评价结果提出福建省山地坡面风景游憩林的构建技术,包括斑块质地的构建、斑块边界线的构建、不同林分年龄风景游憩林管理、群落垂直结构管理、树种组成及配置等。      

A Highly Activated Mineral Admixture Slurry Consisting of a Wet discharged Fly ash and Carbide Lime Composite

To recycle wet discharged fly ash and carbide lime effectively, a highly activated mineral admixture slurry consisting of both these components was investigated. The preparation technology of mineral admixture slurry made from a composite of wet discharged fly ash and carbide lime and the strengths, hydration products change (XRD, SEM) of cement paste made by the slurry were studied. The results indicate that the optimal proportion between wet discharged fly ash and carbide lime (solid content) is 75:25 in the process of wet milling preparation. The alkaline environment provided by carbide lime with high Ca(OH)2content and cement hydration accelerated by modified agents can promote early activation of fly ash, and accelerate its secondary hydration reaction.