Drilling load modeling and validation based on the filling rate of auger flute in planetary sampling

Some type of penetration into a subsurface is required in planetary sampling. Drilling and coring, due to its efficient penetrating and cuttings removal characteristics, has been widely applied in previous sampling missions. Given the complicated mechanical properties of a planetary regolith, suitable drilling parameters should be matched with different drilling formations properly. Otherwise, drilling faults caused by overloads could easily happen. Hence, it is necessary to estab-lish a drilling load model, which is able to reveal the relationships among drilling loads, an auger's structural parameters, soil's mechanical properties, and relevant drilling parameters. A concept for the filling rate of auger flute (FRAF) is proposed to describe drilling conditions. If the FRAF index under one group of drilling parameters is less than 1, this means that the auger flute currently removes cuttings smoothly. Otherwise, the auger will be choked with compressed cuttings. In dril-ling operations, the drilling loads on the auger mainly come from the conveyance action, while the drilling loads on the drill bit primarily come from the cutting action. Experiments in one typical lunar regolith simulant indicate that the estimated drilling loads based on the FRAF coincide with the test results quite well. Based on this drilling load model, drilling parameters have been opti-mized.     

Glacier mapping based on rough set theory in the Manas River watershed

Precise glacier information is important for assessing climate change in remote mountain areas. To obtain more accurate glacier mapping, rough set theory, which can deal with vague and uncertainty information, was introduced to obtain optimal knowledge rules for glacier mapping. Optical images, thermal infrared band data, texture information and morphometric parameters were combined to build a decision table used in our proposed rough set theory method. After discretizing the real value attributes, decision rules were calculated through the decision rule generation algorithm for glacier mapping. A decision classifier based on the generated rules classified the multispectral image into glacier and non-glacier areas. The result of maximum likelihood classification (MLC) was used to compare with the result of the classification based on the rough set theory. Confusion matrix and visual interpretation were used to evaluate the overall accuracy of the results of the two methods. The accuracies of the rough set method and maximum likelihood classification were compared, yielding overall accuracies of 94.15% and 93.88%, respectively. It showed the area difference based on rough set was smaller by comparing the glacier areas of the rough set method and MLC with visual interpreter, respectively. The high accuracy for glacier mapping and the small area difference for glacier based on rough set theory demonstrated that this method was effective and promising for glacier mapping.     

唐长红飞机设计专家

():您两次被任命为总设计师,是否感受到了压力?您是如何面对这些压力的?唐长红:当年接新"飞豹"的时候,有种"初生牛犊"的感觉,而且,当时做过"飞豹"飞机的老同志还有很大一批在岗,所以感觉能减轻一些压力;接国家重点项目的时候,我感觉压力很大.毕竟,这个项目台阶更高、国人寄托的期望更大,而且是亟需的装备.特别是我们的工业基础还有待提高,所以压力还是很大的.     

紧固件柔度系数研究

在飞行器结构中普遍采用紧固件进行结构连接,紧固件的柔度系数是分析紧固件连接细节部位疲劳强度的重要参数.通常,确定紧固件柔度系数的方法多基于试验,但是这需要做大量的试验,耗费巨大.因此希望通过理论方法对紧固件柔度系数进行研究,获得新的计算紧固件柔度系数的方法,以达到减少试验和节省时间的目的.运用材料力学和弹性理论知识,推...     

焊接方法对5A06铝合金厚板焊缝接头性能的影响

分别采用搅拌摩擦焊(FSW)和熔化极氩弧焊(MIG)对20mm厚的5A06铝合金进行了焊接试验,对两种焊接方式的焊缝接头进行了机械性能测试、显微组织的观察以及表面残余应力的检测。结果表明,搅拌摩擦焊缝接头的抗拉强度比熔化极氩弧焊缝接头的高,搅拌摩擦焊缝接头往往断裂于前进侧的熔合过渡区,熔化极氩弧焊缝接头断裂于热影响区;相比熔化极氩弧焊,搅拌摩擦焊接头晶粒明显细化,焊缝中Mg、Mn等合金元素烧损明显减少,焊缝表面的残余应力水平也较低。     

飞机翼面设计中的两个问题

本文针对某型无人机翼面、舵面设计，首先导出了一种确定后掠翼舵面展向缝隙尺寸的计算方法，使用该方法能够定量地计算舵面在极限偏转角下缝隙的尺寸，并指出决定舵面缝隙大小几个主要参数，为舵面缝隙设计提供了可靠依据。同时对翼面修型问题也进行了研究。包括：改变翼型的相对厚度，相对厚度沿展向变化和翼剖面后缘局部修型问题。导出的方法已用于某型无人机设计、制造中，通过缩比模型的风洞吹风试验和首批样机科研试飞验证，舵     

K418合金的组织对低周疲劳性能的影响

研究了Ｋ４１８合金不同宏观组织（晶粒度）对低周疲劳性能的影响，同时研究了不同热处理状态下合金组织中的γ’相及其对合金的低周疲劳性能的影响。     

高温超导滤波器国内外研究进展

近年来，国际上高温超导微波器件的应用取得了重大突破，国内的高温超导微波应用也取得了重要进展。文章介绍了高温超导滤波器的工作原理及其显著特点，回顾了国外高温超导滤波器的研究历史，详细叙述了国内近年在移动通信、卫星微波接收机和气象雷达三方面的应用情况。     

《数据结构》课程教学初探

文章在分析了数据结构教学中存在的问题后 ,按照数据结构课程的结构顺序 ,提出了教学中应注意的问题 ,其目的是使学生能够更好的掌握知识 ,提高分析问题及编程的能力。     

飞摄陌生故土

四川，我是再熟悉不过了，因为它是我的家乡，但当我们飞凌高空，它变得陌生了，不再是平时我的脚所熟悉的土地了。