A continual model of soil organic matter transformations for predicting soil forming dynamics inside higher plant CELSS

A continual model of humification and mineralization of soil organic matter (SOM) formed under the conditions of a Lunar base from biological waste materials is proposed. The model parameters corresponding to the conditions of several Earths climatic regions are estimated. The time necessary for the formation of organic matter in the soil based on regolith and higher plant residues has been evaluated. Soil formation under tropical conditions are shown to be the most appropriate for Lunar base CELSS due to high matter turnover rate, relatively short formation time, minimum deposited mass, and satisfactory predictability of expected soil parameters.     

飞机环控涡轮冷却器轴承壳体制造工艺研究与应用

通过分析轴承壳体的功能和作用,对轴承壳体的结构设计提出了改进方法,并从工艺上实现了轴承壳体的一体化加工。     

卫星承力筒复合材料结构的优化设计

应用JIFEX软件对大型通信卫星主承力结构－－中心承力筒的复合材料结构进行优化设计。在优化设计中考虑了固有频率和屈曲稳定性的约束条件，使用了多种类型的设计变量，对蜂窝夹芯材料采用了一种离散材料变量连续化处理方法。进行了多种方案的优化设计和比较，为承力筒结构研制设计提出了指导性结论。     

Forest biomass monitoring with GNSS-R: Theoretical simulations

GNSS-Reflectometry (GNSS-R) is a remote sensing technique which performs bistatic measurements of the earth surface scattering. This paper presents some theoretical simulations of the specular scattering coefficient of a forested area, with the aim of demonstrating the potentiality of GNSS-R in monitoring forest biomass. The study is performed by means of an electromagnetic model developed in the past years and tested over several vegetation covered sites in its active and passive version. Here, after showing a comparison between model results and measurements over a forest site in the monostatic configuration, and after summarizing other previous validations, the extension to the specular configuration, typical of GNSS-R systems, will be presented. Namely, simulations are carried out at circular polarization and a sensitivity analysis of the received power in the specular configuration to some soil and forest parameters is shown.     

沉管灌注夯扩桩技术及其应用

通过分析沉管灌注夯扩桩技术的工作特点及在实际工程中应用情况，阐述该技术的优越性和最合适使用条件。     

消旋天线机构轴承摩擦力矩研究

叙述了在大气条件下,不同轴向载荷,转速,滚珠数和润滑剂对C7046112轴承摩擦力矩的影响。试验结果表明:轴承轴向载荷与摩擦力矩关系并非单调上升函数,而是一个具有极大值与极小值的周期函数,并对试验结果进行了讨论。文内对进行试验的DZS-1气浮加载轴承动态特性试验设备也进行了介绍。     

Novel design and simulation of curved blade oil scoop with high oil capture efficiency

As the load and working environment temperature increasing, high efficiency oil lubrication was urgently needed for the main bearing of aeroengine. However, the low oil capture efficiency of radial oil scoop affects the application of under-race lubrication structure with radial oil collection. In this work, a novel design of curved blade oil scoop for under-race lubrication is proposed to improve the oil capture efficiency. First of all, the principle of relative velocity optimization is proposed by analyzing the collision process between blade and oil jet for theoretical research. Then, the theoretical curve equations of blade inlet under three different oil jet incidence conditions are solved. After that, the monotonicity of the theoretical curves is analyzed. The effects of rotation speed, oil jet velocity, eccentric distance of oil jet, and include angle of curve are analyzed. The location of the collision points of proposed theoretical curves are also been optimized. Finally, a transient Computational Fluid Dynamics (CFD) simulation of the novel oil scoop design was carried out. The simulation results show that the capture efficiency of curved blade oil scoop can be improved by 30% comparing to the traditional design.     

Retrieval of crop variables with field-based X-band microwave remote sensing of ladyfinger

Modeling in agriculture has been widely used to retrieve and monitor various soil and crop growth variables. Remote sensing, especially radar sensors can be useful for temporal and spatial monitoring of the soil and plant variables. Therefore, in this paper field measurements of crop ladyfinger were carried out to examine the dependency of radar backscatter on crop–soil variables and to develop a method for monitoring and retrieving crop variables for ladyfinger. A crop-bed was prepared to observe scatterometer response in the angular range of incidence angle 20–70° at 9.89 GHz in the X-band for VV- and HH-polarization. At the same time, soil moisture, plant height, leaf area index and aboveground biomass were measured at various growth stages of crop ladyfinger. The angular variation of scattering coefficient decreases with the age of crop ladyfinger shows the dominance of crop effect on soil moisture effect at the older age. Thus, angular trends are more flat as the plant grows since the effects of soil is masked by developing vegetation. Scattering coefficient increases with the increase of leaf area index for both polarizations (i.e. VV- and HH-). It was found that leaf area index and aboveground biomass of crop ladyfinger are highly correlated with microwave frequency more than with plant height and soil moisture. Leaf area index and biomass of ladyfinger crop were retrieved by polarization based model and non-linear least square optimization model. These two models gave very good results for the retrieval of leaf area index and aboveground biomass.     

Cage slip characteristics of a cylindrical roller bearing with a trilobe-raceway

Based on dynamic analysis of rolling bearings, the nonlinear dynamic differential equations of a cylindrical roller bearing with a trilobe-raceway were established and solved by the GSTIFF (gear stiff) integer algorithm with a variable step. The influences of structural parameters and the tolerance of the trilobe-raceway, working conditions of the bearing, and the outer ring installation method on cage slip characteristics were investigated. The results show that: (i) The cage slip ratio and bearing rating life of a cylindrical roller bearing with a trilobe-raceway would reduce when the low-radius (radius of the outer raceway contour at the lowest point) and D-value (difference value between the high and low points of the outer raceway contour) decrease, and the former (low-radius) contributes more significantly. (ii) The cage slip ratio of a cylindrical roller bearing with a trilobe-raceway rises with the increase of the bearing speed, and decreases with the increase of the radial force; the variation range increases with the increase of the low-radius. (iii) When the installation angle of the outer ring increases in a period, the cage slip ratio remains unchanged while the bearing rating life rises up a little. Therefore, when installing a cylindrical roller bearing with a trilobe-raceway, the location of the maximum radius shall be under that of the radial force to improve the bearing rating life. (iv) With the increase of the roundness of the base circle where the radius of the lowest points of the trilobe-raceway contour locates, the cage slip ratio rises gradually and the bearing rating life decreases.     

气体静压止推轴承静动态性能及振动抑制

为探讨抑制气体轴承自激振动的新手段,研究了圆盘形单个小孔节流的气体静压止推轴承振动问题。通过两平行圆盘间的气体流动方程,推导建立了气体轴承静动态特性分析模型。通过数值分析的方法,研究并总结了供气压力和气膜厚度对气体轴承静态承载力、静态气体质量流量、静动态刚度以及动态阻尼的影响,计算得到了一系列气体轴承静动态特性变化曲线。然后针对系统出现负阻尼情况,通过引入非线性能量阱(NES)来抑制自激振动的问题。研究结果表明,提高供气压力可以有效地提高气体轴承的静态性能;气体轴承的自激振动主要源于气膜挤压的负阻尼特性;同时,当NES的阻尼超过临界阻尼时,可以使系统的振动得到有效的抑制。