Plastic upper bound theory reliability analysis of coal gangue hills

We established the plasticity limit analysis reliability limit state equation and the reliability calculating formula for gangue hills using the JC method. This work was based on the plasticity mechanics limit analysis upper bound theory and traditional slice methods. A reliability index of gangue hill stability was derived using this equation. It was found that the safety coefficient of gangue hills derived by the limit state equation risks failure if the variability of cohesion and internal friction angle are not considered. When the variability of the strength parameters rises, the reliability theory more consistently projects practicality than the limit state equation for gangue hill stability assessment.     

2003～2007年《管子学刊》载文及作者统计分析

运用文献计量学的方法,对《管子学刊》2003～2007年载文及作者情况进行了统计和分析。     

氧硫化碳熏蒸处理对苹果贮藏品质的影响

氧硫化碳作为一种新型环保的溴甲烷替代熏蒸剂,在水果检疫处理中可能有着广泛的应用前景.本文探讨了25℃条件下不同剂量氧硫化碳熏蒸处理对苹果主要贮藏品质指标的影响.结果表明,处理组苹果呼吸作用在熏蒸过程被显著增强,却在储藏期间被抑制;熏蒸处理对储藏期苹果的失重有显著的抑制作用;熏蒸处理对储藏期苹果的硬度、可溶性糖和总酸度均无明显影响;90 g/m3的氧硫化碳熏蒸4h,苹果表皮无药害.     

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.     

北疆沟灌大豆单产350 kg/667 m^2栽培技术

大豆富含蛋白质、脂肪和维生素等,其深加工产品已成为人们生活中重要的食品之一。本文从品种选择、播种、田间管理、收获等方面,介绍了新疆北疆春大豆的高产栽培技术。     

contact stress and steady thermal analysis of herringbone gears in a gas turbine

To obtain the distribution characteristic of contact stress and the bulk temperature on the surface of herringbone gears, parameter modeling of gears was carried out by parametric design language. A numerical simulation was given to calculate the contact stress field and the steady thermal field by combining heat transfer theory, tribology theory, and mesh theory. The distribution of contact stress, the bulk temperature and heat flux also were analyzed. The analysis results show that the distribution of the load along the contact line possesses regularity. The heat flux along the tooth depth direction decreases first and then increases. The effect of thermal conduction of the tooth is stronger than that of convective heat transfer. The conclusion indicates that the finite element emulation method can be used to estimate the transmission performance of herringbone gears.     

耕地土壤容重作用及其调控途径研究进展

近年来,由于农业机械化的不断发展、化肥施用量的增加以及不合理的耕作、灌溉措施,导致我国耕地土壤质量问题日益凸显,影响作物出苗、发育和产量。土壤容重是土壤主要结构特性之一,与土壤孔隙度、土壤通透性以及土壤蓄水保墒能力密切相关,对作物地上部和根系生长有重要作用。该研究结合近几年国内外研究进展,从耕地土壤容重对作物生长的作用机理、土壤容重的影响因素、土壤容重的调控途径等3个方面分析阐述了人工调控改良耕地质量的可行性,最后对改良土壤容重在作物生长发育过程中的应用做出展望,以期为耕地土壤容重调控途径的进一步研究提供参考依据。     

Agouti基因及其与动物毛色关系的研究进展

动物特别是毛皮动物,毛纤维颜色丰富多彩,其主要由遗传基因调控,在众多的调控基因中,Agouti基因是一个重要的功能基因。论文重点综述了Agouti基因结构及其在人、小鼠、家养普通动物和毛皮动物毛色方面的研究现状,旨在为动物毛色选育提供参考依据。     

温度对猪圆环病毒培养滴度的影响

为了猪圆环病毒生产批次间滴度的稳定性,提高病毒产量,本实验对猪圆环病毒的培养温度参数进行了研究.结果显示,病毒培养温度36℃时,收获毒液病毒滴度明显下降,培养温度为37℃和38℃时,病毒滴度基本持平,均能稳定在较高水平.