太阳轨道运动的2400年周期与轨道周期

通过对行星会合指数运动学方程生成的数据进行傅里叶变换, 得到了从年、十年、 百年、千年、万年到十万年时间尺度的周期, 发现这些周期具有后者是前者10n 倍的特殊倍乘关系. 如果将通过傅里叶变换得到的年时间尺度最显 著的周期4.96488a设为单位时间步长代入行星会合指数方程, 则可得到稳定 的2400年周期. 在此基础上由2400年周期振幅的差异性又构成了更长时间尺度的 10万年和40～41万年太阳轨道运动特征周期. 这对于揭示太阳轨道运动与太 阳活动的关系, 以及探讨气候千年尺度和轨道周期变化规律的机制具有重要意义.      

A physics-based framework for online surface roughness assessment for high-pressure turbines

Surface roughness is a critical health parameter of a turbine blade due to its implications on blade surface heat transfer and structural integrity. This paper proposes a physics-based online framework for Gas Turbine Engines (GTE), in order to assess the blade surface roughness in a high-pressure turbine without engine shutdown. The framework consolidates Gas Path Analysis (GPA) based performance monitoring models and meanline turbomachinery analysis, using a novel GPA-meanline matching process. This extracts meaningful performance deviation trends from GPA, while addressing the uncertainties associated with the measurements and modelling. To relate efficiency loss to surface roughness severity, a meanline-based system-identification process has been developed to establish the meanline representation of the turbine stage, and to incorporate the empirical surface roughness loss correlations. The roughness loss correlations have been evaluated against recent transonic test data in the literature. A modification to the compressibility correction factor has been made according to the evaluation outcome, which improved loss predictions compared to the experimental measurements. The framework was tested on the three-year operational data of a cogeneration GTE, and the results verified the framework's potential for online surface roughness monitoring. The predicted surface roughness showed agreement in both trend and the magnitude-level with the measurements reported in the literature.     

导弹武器系统时间同步网的综合性能评估方法

针对导弹武器系统时间同步网（MWSTSN）现有评估方法不全面、不客观等问题,提出了一种基于权系数优化的导弹武器系统时间同步网的综合性能评估方法。首先,基于时间同步网的工作流程与系统结构,综合分析了影响系统性能的各项指标,建立了导弹武器系统时间同步网性能的评估体系与评估模型。通过构建主、客观指标权重的分配系数最优化模型,利用层次分析法和熵值法对上述指标进行组合赋权,获取具有主、客观特性的组合权重。最后,通过案例验证上述评估过程的有效性,结果表明：该评估体系能够有效反映导弹武器系统时间同步网中各分系统及设备的可用性,并具备可测性和可操作性。     

基于脉冲暂态混沌神经网络的可靠度分析方法

工程中计算结构可靠度系数β可以看做一个优化问题。考虑极限状态函数的非线性程度很高且存在非凸失效域时,传统的求解非线性优化方法,如序列二次规划（SQP）法、罚函数法和梯度投影法等都有其使用范围和局限性,无法解决局部极小解问题。如何避免局部极小解问题并且兼顾计算精度和效率目前仍很难处理。提出一种新的可靠度计算方法：将求解转化为带有约束条件的非线性规划问题,利用罚函数法转化成无约束条件的非线性规划问题,引入脉冲暂态混沌神经网络（PTCNN）模型快速有效地进行全局寻优,从而解决具有局部极小解的约束非线性规划问题。最后采用不同类型的非线性极限状态函数算例进行算法验证,验证该方法在处理高维、高非线性、不可微、非凸失效域问题时具有可行性、高效性。     

Response of photosynthetic systems to salinity stress in the desert cyanobacterium Scytonema javanicum

The present study investigated the physiological and biochemical characteristics of Scytonema javanicum, a pioneer species isolated from desert biological crusts, under salinity stress. Pigment analysis showed that salinity decreased chlorophyll a and phycocyanin content, while low salinity increased carotenoid concentration and high salinity decreased carotenoid concentration. Salinity also inhibited CO₂ assimilation rate and photosynthetic oxygen evolution in this cyanobacterium. Chlorophyll a fluorescence transient parameters (φPo, φEo, ψO, RC/ABS, RC/CS, PI_ABS, and PI_CS) were decreased under salt stress, while dVo/dto(Mo), Vj and φDo were increased. The decrease of ETRmax and Yield and the change of chlorophyll a fluorescence transients showed that salt stress had an important influence on photosynthesis. These results indicated that the effects of salinity stress on photosynthesis in S. javanicum may depend on the inhibition of electron transport and the inactivation of the reaction centers, but this inhibition may occur in the electron transport pathway at the PSII donor and acceptor sites.     

Quasi-biennial oscillation signals in outgoing long-wave radiation of the equator

In the present paper, the authors use wavelet transform technique to study time-series of outgoing long-wave radiation (OLR) anomaly at the equator during 1979–2005. The results show that quasi-biennial oscillation (QBO) signals exist in the OLR variation and the QBO cycle has remarkable temporal variability in its amplitude and phase. The periodic length of the QBO fluctuation is about 2.2-year before 1986. After that time, the length mainly changes from about 2.4- to 2.6-year. Analyzing the anomaly data set of 850 MB trade wind index (TWI) at west Pacific during this period, we have found that the obvious time-variations characteristics of the QBO cycle also exist in the TWI change at west Pacific and are in good consistence with that of the OLR change. The quasi-biennial fluctuation of the TWI change can explain that of the OLR change to a large extent.     

中国广州地区电离层闪烁观测结果的初步统计分析

利用在广州站(23o8' N, 113o17' E)建立的GPS电离层闪烁监测系统, 开展了对电离层闪烁的连续观测. 利用这些观测数据, 对广州地区2007年4月至9月及2008年1月至9月电离层闪烁变化特性进行了初步统计分析研究. 分析结果表明, 广州地区闪烁主要发生在太阳活动较低的磁静日期间. 季节变化表现为弱闪烁(0.2相似文献   

电离层暴时经验模型STORM在中国区域的适应性研究

利用中国区域内9个垂测站1976---1987年一个太阳活动周期的电离层暴时f0F2数据, 统计分析了电离层暴事件的等级, 以及不同等级的电离层暴随季节和地磁纬度的分布特征. 研究发现, 中小型电离层暴在春秋季发生的概率较大, 不同季节的发生次数与地磁纬度具有明显的关系. 利用STORM模型对电离层暴时f0F2和大型及特大型电离层暴时f0F2的预测值与月中值进行了比较. 结果表明, 除了冬季误差增大外, 发生电离层暴时STORM模型能够有效地改善月中值模型. 增加中国的暴时数据, 并提高对冬季的暴时参数f0F2的预测是改善STORM模型的重要因素. 建立合适的暴时指数来预测f0F2是未来研究的重点.      

缝合复合材料层合板面内拉伸强度的分析

提出了缝合复合材料层合板抗拉强度的微观分析方法,建立了针脚处纤维局部弯曲的几何模型。使用最大应力准则和强度破坏指标相结合的方法,根据主承力层的失效得到层合板的抗拉强度。计算结果表明,理论预测值与试验结果吻合良好,证实了该模型的正确性和可靠性。     

民机驾驶舱工效学综合评价方法研究及应用

飞机驾驶舱工效学综合评价是驾驶舱研制中一个极其重要的问题,以往在驾驶舱的研制过程中往往为其工程质量提出种种衡量标准而忽视工效学的综合评价,导致设计出的驾驶舱存在不少工效学方面的问题。为此,结合民机驾驶舱工效学的实际情况,本文提出一种将改进专家打分法、三标度层次分析法和模糊综合评判法集成的综合评价体系,给出了合适、可操作的评价指标和评价方法,能指导驾驶舱的工效学评价。该体系考虑了工效学评价的模糊性,实现了征求和提炼专家群体的意见,对飞机驾驶舱工效学进行了定量地综合评价,为比较相似设计方案的优劣提供了理论基础和方法。应用此方法,结合研究项目,对某民机驾驶舱尺寸设计的工效学进行了评价,证明了该方法的有效性。