冲击响应谱时域合成算法研究

为利用电动振动台进行模拟冲击环境试验给出了一种时域冲击波形合成方法.依据冲击响应谱时域合成的一般原则,选择合成小波中的正弦窗波作为基本波形,给出了确定各基本波形的波形参数的方法.计算结果表明本文所提算法是有效的,所合成的时域冲击波形能够满足参考冲击响应谱的精度要求,为开发冲击谱试验的控制软件研究者提供了一种思路.     

Mount St. Helens: A case study of managing for change in wildland recreation

Mount St. Helens provides an interesting case study of a forest and wildland area that has been radically altered in recent history. As a result of volcanic activity, the recreation environment has changed with respect to the setting, climbing opportunities, and motivations for mountaineering. An evaluation process using both qualitative and quantitative methods was developed to determine what the motivations, demographic characteristics, and preferred management techniques were for the posteruption Mount St. Helens mountain-climbing visitor. Results suggest that changes have occurred in the “new” or posteruption climbing visitor. These changes have not all been congruent with those anticipated by management. For example, the climbing visitor is now less interested in climbing opportunities and more concerned with seeing the crater and other volcanic-related features. This article discusses the findings of this research in light of how resource managers might consider the issue of visitor changes in both demands and types of uses. For example, determining quota numbers based on sociological determinants (e.g., desire for solitude) need to be firmly grounded in who the visitors actually are rather than who they were. Consequently, management tools such as the Recreational Opportunity Spectrum (ROS) and Limits of Acceptable Change (LAC) may need to be altered to accommodate a changing resource or visitor base. These and other findings have implications for the future management practices of the Mount St. Helens area and other environments where the recreation resources have undergone rapid and profound change.     

环空带压气井保护液液位测试方法研究

为了有效检测环空保护液位,评估气井环空带压情况,在传统回声法检测的基础上,提出了基于频谱分析及自相关分析的2种液位检测方法;搭建了液位检测试验系统,开展了不同环空压力下的液位检测试验,计算了不同压力下的环空声速;设计了FIR低通滤波器对液面回波信号进行滤波处理,同时利用了上述2种方法计算液位值并与实际值及传统液位计算方法对比,得出了声衰减系数并评判了衰减过程对液面回波信号频谱分析的影响程度。研究结果表明:设计的FIR低通滤波器适用于所建液位检测试验的滤波处理过程;频谱分析及自相关分析都能够有效检测液位高度,最大误差分别为1.65%和0.61%,自相关分析方法具有更高的精确度;声衰减系数整体较小,对液面回波信号频谱分析结果影响较小。     

The influence of confounding factors on the relationship between muscle contraction level and MF and MPF values of EMG signal: a review

The purpose of this article is to gather results of studies on the relationship between median frequency (MF) and mean power frequency (MPF) and the level of muscle contraction, and to use those results to discuss the differences in the trends according to factors related to measurement technique and subject. Twenty-one studies with 63 cases for upper limb muscles and nine studies with 31 cases for lower limb muscles were analysed. Most results showed an increase in parameters with an increased level of muscle contraction, only some studies showed a decrease. The influence on parameters of the level of muscle contraction and factors such as subjects, type of contraction, muscle length and electrodes was analysed for each muscle. It was concluded that when analysing the influence of different factors on MF and MPF, because those factors interact they should be considered together, not separately.     

珊溪水库库区及入库支流水体紫外光谱特征分析研究

珊溪水库是温州地区的重要饮用水源地之一。在“五水共治”时代背景下,“保供水”特别是确保我市饮用水源安全是“五水共治”的组成部分之一。本文采用紫外光谱特征分析法评估珊溪水库主库区及主要入库支流考核断面水环境质量状况。分析结果表明：从黄坦坑、李井坑等监测站位的紫外特征吸收峰SUVA254分析二者污染较重,有机质芳化度、分子量和腐殖化水平相对较大。库区胡敏酸含量比富里酸含量大,支流天然水溶解性有机质( DOM)有机物分子缩合度高,腐殖化程度从支流到水库逐渐增大。     

弱粘煤低温氧化活性基团与热效应的研究*

为研究煤氧化过程中活性基团的演变规律及热效应的变化特征,利用原位红外实验装置,实时测量煤升温过程中官能团的动态变化,数据处理得到弱粘煤红外波谱图,利用差减法对特征温度点下的红外光谱图进行处理,得到煤样的差示光谱,计算特征温度点下的红外结构参数;采用差示扫描量热仪,测量煤氧化过程中热流的变化,得到弱粘煤的热流曲线图,并对热流曲线进行阶段划分和氧化动力学计算。结果表明:弱粘煤中芳环数量比较少,环周围侧链较长,内部结构疏松,内部毛细管比较发达,内表面积较大,更容易发生自燃;整个氧化过程中羟基最为活跃,含氧官能团次之,其次是脂肪烃;红外参数计算结果HAL,I2整体呈减小趋势,I1,I3整体呈增大趋势;弱粘煤放热阶段的活化能值为25.12～61.26 kJ/mol,并随着升温速率的增大而减小,与此阶段放热量随升温速率的增大而增大相对应。     

火山玻璃的拉曼光谱研究

本文分析了浙、闽、赣地区产于玄武岩、安山岩、流纹岩、黑曜岩及珍珠岩中玻璃相的拉曼光谱特征,认为酸性火山岩中的玻璃相分子团结构基本上由类似于结晶学上的、但在三维方向完全无序的链状、层状、架状及纯架状网络体组成,而中基性火山岩中的玻璃相结构仅由前三者组成。玻璃相分子团结构与其断健程度(DBB)间受一维延长的链状网络体(Ch)的含量正向控制及三维扩展的纯架状网络体(Ne~*)的含量负向控制,一元回归线性方程、相关系数R、拟合度F,分别是: 经研究,其中的黑曜岩可能是岩浆喷发间歇后的另一次爆溢产物。     

萃取火焰原子吸收法同时测定土壤及蔬菜中铅镉的条件

用TOA-IBK系统革取,火焰原子吸收光谱法在同一条件下测定土壤、蔬菜中的铅镉.考察了TOA、KI、盐酸、抗坏血酸用量、革取时间、放置时间及在同等实验条件下钙、镁、铁等金属离子和酸的用量的干扰影响情况.     

装备关重件腐蚀-疲劳环境/载荷试验谱编制方法研究

目的 研究装备关重件大气腐蚀-动态疲劳协同加载的环境/载荷试验谱编制方法。方法 依据装备构件服役寿命-环境剖面,分析腐蚀环境与疲劳应力协同作用的特点,归纳出腐蚀-疲劳环境/载荷谱的设计原则和编制方法。结果 利用环境/载荷谱编制方法制定了某装备结构件腐蚀环境与疲劳载荷协同作用的加速试验谱。结论 建立的腐蚀-疲劳协同作用的环境/载荷谱编制方法及当量加速试验谱,可用于研究装备关重件的腐蚀-疲劳协同环境效应及加速试验评价方法等工作。     

基于UV-vis和EEMs解析白洋淀冬季冰封期间隙水DOM的光谱特征及来源

基于三维荧光光谱（EEMs）技术结合平行因子分析法（PARAFAC）以及紫外-可见光谱技术（UV-vis）,对雄安新区-白洋淀冬季冰封期不同特征区域间隙水溶解性有机物（DOM）的光谱特征以及来源进行解析.结果表明：冬季冰封期白洋淀不同特征淀区间隙水DOM的相对浓度差异显著,养殖区的最高、旅游区的最低;冰封期白洋淀大部分区域间隙水DOM的E₃/E₄均大于3.5,说明DOM以低腐殖质成分为主;三维荧光通过PARAFAC解析出3种组分,分别为类酪氨酸（C1）、类色氨酸（C2）和陆源腐殖质（C3）;对3个组分进行相关性分析,结果显示C1与C2之间的相关系数达到0.99（p<0.001）;白洋淀各个特征区域间的DOM总荧光强度和各荧光组分相对丰度呈现显著的差异（p<0.05）;DOM的总荧光强度以及各组分的荧光强度均呈现出唐河入淀口高的特征,C1+C2是DOM的主要成分呈现养殖区多、自然区少的特点,养殖区达到79.30%~92.04%,自然区达到26.60%~38.55%;冰封期白洋淀间隙水水体的DOM荧光指数FI为（2.58±0.23）>1.8,生物源指数（BIX）为1.20±0.25,表明白洋淀DOM来源于生物活动并且以自生源为主,与腐殖程度指标（HIX）的结果相吻合;a₂₅₄与硝氮、溶解性总磷和A₂₅₄/A₂₀₄,a₃₅₅与S_350~400;a₄₄₀与S_275~295、S_350~400、E₂/E₄、E₂/E₆和E₄/E₆,C1以及C2与Fn₂₈₀,C3与硝氮和Fn₃₅₅相关性很好（p<0.05）.综上,通过对冬季冰封期白洋淀各个典型淀区间隙水水体DOM光谱特征进行研究,可以为分析白洋淀水体有机物污染特征和白洋淀的水质管理提供技术支持.