Analysis of driving efficiency for LRV wheels using forced-slip method

To investigate and improve the mobility of the Lunar Roving Vehicle (LRV), it is necessary to consider the mechanical properties of the interaction between the wheels and the ground. In this paper, a new solution method, the forced-slip solution method, which uses a semi-empirical approach, was presented. That is, given the wheel’s vertical load and drawbar pull or driving torque as known input values, the unknown slip ratio can be resolved. The alternative method involves predicting the mechanics for a given slip ratio. The proposed method correlates better with actual wheel movements, and by studying a single wheel, this solution method can also be used to resolve the mechanical properties of the front and rear wheels in a four-wheel-drive (4WD) LRV configuration. It can also be used to consider the multi-pass effect of the rear wheels on lunar soil. The calculation results show that the 4WD LRV driving efficiency varies with the position of the center of mass. Thus, the LRV driving efficiency can be optimized by adjusting the position of its center of mass.     

Experimental study on effect of inclination angles to ammonia pulsating heat pipe

In this paper, a novel study on performance of closed loop pulsating heat pipe（CLPHP）using ammonia as working fluid is experimented. The tested CLPHP, consisting of six turns, is fully made of quartz glass tubes with 6 mm outer diameter and 2 mm inner diameter. The filling ratio is50%. The visualization investigation is conducted to observe the oscillation and circulation flow in the CLPHP. In order to investigate the effects of inclination angles to thermal performance in the ammonia CLPHP, four case tests are studied. The trends of temperature fluctuation and thermal resistance as the input power increases at different inclination angles are highlighted. The results show that it is very easy to start up and circulate for the ammonia CLPHP at an inclining angle.The thermal resistance is low to 0.02 K/W, presenting that heat fluxes can be transferred from heating section to cooling section very quickly. It is found that the thermal resistance decreases as the inclination angle increases. At the horizontal operation, the ammonia CLPHP can be easy to start up at low input power, but hard to circulate. In this case, once the input power is high,the capillary tube in heating section will be burnt out, leading to worse thermal performance with high thermal resistance.     

FeS/S/FeS(2) redox system and its oxidoreductase-like chemistry in the iron-sulfur world

The iron-sulfur world (ISW) theory is an intriguing prediction regarding the origin of life on early Earth. It hypothesizes that life arose as a geochemical process from inorganic starting materials on the surface of sulfide minerals in the vicinity of deep-sea hot springs. During the last two decades, many experimental studies have been carried out on this topic, and some interesting results have been achieved. Among them, however, the processes of carbon/nitrogen fixation and biomolecular assembly on the mineral surface have received an inordinate amount of attention. To the present, an abiotic model for the oxidation-reduction of intermediates participating in metabolic pathways has been ignored. We examined the oxidation-reduction effect of a prebiotic FeS/S/FeS(2) redox system on the interconversion between several pairs of α-hydroxy acids and α-keto acids (i.e., lactate/pyruvate, malate/oxaloacetate, and glycolate/glyoxylate). We found that, in the absence of FeS, elemental sulfur (S) oxidized α-hydroxy acids to form corresponding keto acids only at a temperature higher than its melting point (113°C); in the presence of FeS, such reactions occurred more efficiently through a coupled reaction mechanism, even at a temperature below the phase transition point of S. On the other hand, FeS was shown to have the capacity to reversibly reduce the keto acids. Such an oxidoreductase-like chemistry of the FeS/S/FeS(2) redox system suggests that it can determine the redox homeostasis of metabolic intermediates in the early evolutionary phase of life. The results provide a possible pathway for the development of primordial redox biochemistry in the iron-sulfur world. Key Words: Iron-sulfur world-FeS/S/FeS(2) redox system-Oxidoreductase-like chemistry. Astrobiology 11, 471-476.     

Interplanetary Lyman α Observations: Intensities from Voyagers and Line Profiles from HST/STIS

We present an analysis of Voyager UVS data obtained between 1993 and mid-2007. These data are used to study the interplanetary background and the hydrogen number density in the outer heliosphere. Two types of observations are studied, first the heliospheric scans performed until 2003 and then the fixed line of sight observations, close to the upwind direction, which are still performed at the end of 2007. We make comparisons with models including multiple scattering and hydrogen distributions derived from self-consistent modeling of the interface region. It is found that there is a remaining discrepancy between models and data. The origin of this difference is unknown but it may be linked to a possible tilting of the heliospheric interface due to the presence of an interstellar magnetic field. We should also estimate alternate sources of emission which are not backscattering of solar photons like collisional excitation of hydrogen in the heliosheath and emission after charge transfer or recombination of proton and electron in HII regions. Line profiles from HST/STIS are also presented.     

变幅单频交流信号幅度的同步采集方法

叙述和介绍了采集交流信号的常用方法，指出了常用方法在采集幅度快速变化的交流小信号时存在的缺陷。在此基础上提出了一种新的交流信号同步采集方法，适合于对采样率和采集精度要求较高的场合。     

驾驶员建模精度分析方法的改进及应用

研究了驾驶员建模精度分析方法和提高建模精度的途径。基于驾驶员在环实时仿真结果,识别驾驶员描述函数,按加权最小二乘准则采用复形调优算法识别模型参数。结合两步识别过程,针对现有模型精度公式在最终模型检验上的缺陷,进一步完善了精度评价公式。根据公式提出了基于灵敏度分析的驾驶员模型参数调整方法。应用结果表明：所建立的公式和方法对提高驾驶员模型建模精度效果明显。     

The hemispheric asynchrony of polar faculae during solar cycles 19–22

We investigate the north–south (N–S) asynchrony of the polar faculae and compare it with the hemispheric asynchrony of solar activity at low latitudes. We find that, (1) both the solar activity at high and low latitudes do not synchronously occur in the northern and southern hemispheres, there is phase shifts between the two hemispheres; (2) the N–S asynchrony of the polar faculae is a function of latitudes, implying that the asynchrony of the polar faculae between the two hemispheres is related to the hemispheric asymmetry and latitudinal distribution of the polar faculae.     

基于FCA具有认知诊断功能CAT的设计与实现

认知诊断（Cognitive diagnosis,CD）是智能教学系统的重要组成部分,但其研究存在一些问题：且对具有认知诊断功能的计算机化自适应测验（Computerized adaptive testing,CAT）的报导很少。CAT因人施测,公平高效,适合大规模测验。在规则空间模型与属性层次法的理论基础上,提出新的属性层次结构的类型,将形式概念分析（Formal concept analysis,FCA）应用于CD-CAT,以概念格为其理论模型,采用合适的题库建设技术、CD-CAT的选题策略和估计方法,建立概念格与CD-CAT的联系,据此开发出CD-CAT以实现对被试的实时诊断并讨论认知诊断的算法。采用Monte Carlo模拟进行实验,实验结果表明被试的知识状态较好地被诊断,能力估计精度在89%以上。     

水平轴风车叶轮侧偏或上仰时的气动力计算与分析

本文将动量-叶素理论推广应用于计算水平轴风车叶轮有侧偏角或上仰角时的气动力。计算结果与实验数据比较表明:这种计算方法简单快速,并有一定的准确度。所得结果对合理设计小型水平轴风车侧偏式或上仰式限速机构很有用。     

高超声速化学平衡流辐射流场数值解

本文用数值方法研究了高超声速大钝头体绕流辐射流场。采用粘性激波层控制方程和平衡化学反应气体模型。辐射部份包括连续辐射和线辐射。采用切平板辐射输运模型解决了空间推进的问题，计算结果表明：辐射传热与飞行器再入飞行速度，高度及头部半径密切相关，在计算的条件下，当再入速度小于７．６公里／秒时，辐射传热的影响可以忽略，当再入速度为１１公里／秒左右时，辐射传热可以与对流传热相比拟。当再入速度更大时，辐射传热远