青藏高原北缘P波波形线性度的动态跟踪及其变化的物理机制初探

利用数字化近震Ｐ波波形资料，追踪研究了青藏高原北缘１９９０年２月～１９９５年８月Ｐ波波形时间线性度的变化过程。发现该区较大地震发生前线性度有一定程度的下降现象。分析认为：大震前孕震区应力场的不均匀分布可使通过孕震区及其周缘的地震波产生频散，可能是较大地震前波形时间线性度下降的物理本质     

北京地区15000年以来环境变迁中灾害性气候突变事件的讨论

通过高分辨率孢粉分析及烧失量、炭屑实验结果的统计分析，结合１４Ｃ、古地磁等，对北京房山东甘池１５０００ａ以来植被变化和环境变迁进行了较为深入的研究，特别强调气候变化的灾害性突变事件。初步得知约在１４１００～１４０００ａＢ．Ｐ．前后曾出现与哥得堡反转相对应的事件，在１００００ａＢ．Ｐ．左右出现类似与新仙女木事件相对应的事件，在大约５７７０ａＢ．Ｐ．和４５６０ａＢ．Ｐ．左右及２８５０～２６５０ａＢ．Ｐ．出现了大暖期的突然降温事件。     

超高强度钻杆低温断裂性能及裂纹扩展特征研究

超高强度钻杆在冬季低温环境下容易发生脆性断裂事故,为了从断裂力学角度揭示其冷脆现象的本质,采用ZBC2302-D型示波冲击试验机,获得了不同温度下超高强度钢在冲击断裂过程中的力-位移曲线,并对比分析了冲击功、起裂功和裂纹扩展功之间的变化关系。采用国家标准GB 4161—2007中的计算公式,计算了冲击试样的裂纹扩展量Δa和阻抗应力强度因子K_R;同时,引入K_R阻力曲线,得到超高强度钻杆在不同温度下的剩余强度图。结果表明,当冲击试样开始出现裂纹时,随温度降低,钻杆的初始起裂应力有所增加,出现硬化现象。当钻杆出现一定长度的裂纹时,随温度降低,阻抗应力强度因子越来越小,而且降低速度越来越快,剩余强度也表现出相同的变化趋势。随温度降低,材料抵抗裂纹扩展的能力逐渐下降,表明钻杆在低温下更容易断裂。     

Estimating abundance without recaptures of marked pallid sturgeon in the Mississippi River

Abundance estimates are essential for assessing the viability of populations and the risks posed by alternative management actions. An effort to estimate abundance via a repeated mark‐recapture experiment may fail to recapture marked individuals. We devised a method for obtaining lower bounds on abundance in the absence of recaptures for both panmictic and spatially structured populations. The method assumes few enough recaptures were expected to be missed by random chance. The upper Bayesian credible limit on expected recaptures allows probabilistic statements about the minimum number of individuals present in the population. We applied this method to data from a 12‐year survey of pallid sturgeon (Scaphirhynchus albus) in the lower and middle Mississippi River (U.S.A.). None of the 241 individuals marked was recaptured in the survey. After accounting for survival and movement, our model‐averaged estimate of the total abundance of pallid sturgeon ≥3 years old in the study area had a 1%, 5%, or 25% chance of being <4,600, 7,000, or 15,000, respectively. When we assumed fish were distributed in proportion to survey catch per unit effort, the farthest downstream reach in the survey hosted at least 4.5–15 fish per river kilometer (rkm), whereas the remainder of the reaches in the lower and middle Mississippi River hosted at least 2.6–8.5 fish/rkm for all model variations examined. The lower Mississippi River had an average density of pallid sturgeon ≥3 years old of at least 3.0–9.8 fish/rkm. The choice of Bayesian prior was the largest source of uncertainty we considered but did not alter the order of magnitude of lower bounds. Nil‐recapture estimates of abundance are highly uncertain and require careful communication but can deliver insights from experiments that might otherwise be considered a failure.     

PLC控制系统在钢渣热焖工艺中的应用

利用PLC控制系统,实现在钢渣热焖工艺中的恒压供水和钢渣热焖定时定量喷水的自动控制要求,具有国际先进水平,取得了良好的经济效益、社会效益和环境效益.     

船用E500钢在海水中阴极极化氢脆敏感性研究

目的研究阴极保护电位对E500钢在海水中氢脆敏感性的影响。方法采用慢应变速率拉伸试验(SSRT),同时利用三电极体系进行不同电位极化,并结合扫描电镜进行试样断口观察。结果随着阴极保护电位负移,E500钢在海水中的氢脆敏感性增加,阴极保护电位为-0.95 V(vs.SCE)时,拉伸试样出现脆性解理断裂特征,电位为-1.00 V时,E500钢断口呈脆性断裂特征。结论根据氢脆系数拟合曲线得出,当氢脆系数达到25%时,E500钢最负阴极保护电位应为-0.913 V。     

热带海洋大气环境下X70管线钢的缝隙腐蚀行为研究

目的研究X70管线钢在热带海洋大气实海环境下的缝隙腐蚀行为。方法在距离湛江东海岛海岸50m和200 m处分别搭建楔型缝隙模型,安装大气环境Cl-收集装置和自动气象监测站。结果距离海岸越近,风速越大,大气中Cl-沉降速率也越大,X70管线钢缝隙腐蚀越严重。X70管线钢在距离海岸50 m处发生缝隙腐蚀的最大缝宽约为0.96 mm,200 m处最大缝宽约为3.75 mm,50 m处缝隙腐蚀更严重。结论缝隙腐蚀区域形成了氧浓差电池,同时随着缝隙液中Cl-向缝隙内迁移,发生闭塞区电池自催化过程,在二者共同作用下,缝隙腐蚀区域较非缝隙腐蚀区域腐蚀更严重。     

九龙江口滨海湿地生源要素空间分布特征

为了揭示亚热带典型滨海湿地生源要素的空间分布特征及影响因素,选取九龙江口滨海湿地为研究对象,于2009年夏采集表层沉积物及柱状样,利用元素分析仪和流动注射分析仪对主要生源要素碳、氮、磷、硫(C、N、P、S)进行分析.结果表明,九龙江口滨海湿地生源要素含量较高,总碳、总氮、总磷、总硫(TC、TN、TP、TS)的均值分别为(12.64±2.66)、(1.57±0.29)、(0.48±0.06)、(2.61±1.37)g·kg-1,空间分布差异性显著.红树林植被区表层沉积物的TC、TN、TP含量高于米草植被及光滩,高潮位TC、TN、TP含量>中潮位>低潮位,TS在米草植被及中潮位含量较高.柱状样的TC、TN具有相似的垂直变化趋势,均表现为由表层向下逐渐降低,且不同植被间的柱状样TC、TN含量在同一深度上都表现为:红树区>米草区>光滩区;柱状样TP平均值是光滩最低,TS平均值是光滩最高.冗余分析表明,植被类型、pH及潮位是影响表层沉积物生源要素(C、N、P、S)分布最显著的环境因子,解释量分别为24.0%、19.0%和11.6%.     

Speciation of organic phosphorus in a sediment profile of Lake Taihu II. Molecular species and their depth attenuation

The understanding of organic phosphorus(P) dynamics in sediments requires information on their species at the molecular level,but such information in sediment profiles is scarce.A sediment profile was selected from a large eutrophic lake,Lake Taihu(China),and organic P species in the sediments were detected using solution phosphorus-31 nuclear magnetic resonance spectroscopy(31 P NMR) following extraction of the sediments with a mixture of 0.25 mol/L NaOH and 50 mmol/L EDTA(NaOH-EDTA) solution.The results showed that P in the NaOH-EDTA extracts was mainly composed of orthophosphate,orthophosphate monoesters,phospholipids,DNA,and pyrophosphate.Concentrations of the major organic P compound groups and pyrophosphate showed a decreasing trend with the increase of depth.Their half-life times varied from 3 to 27 years,following the order of orthophosphate monoesters > phospholipids DNA > pyrophosphate.Principal component analysis revealed that the detected organic P species had binding phases similar to those of humic acid-associated organic P(NaOH-NRP HA),a labile organic P pool that tends to transform to recalcitrant organic P pools as the early diagenetic processes proceed.This demonstrated that the depth attenuation of the organic P species could be partly attributed to their increasing immobilization by the sediment solids,while their degradation rates should be significantly lower than what were suggested in previous studies.     

化学铁盐辅助除磷对生物除磷的影响研究

化学辅助除磷有助于污水厂实现磷达标,但其对生物系统存在潜在的影响。针对除磷药剂对生物除磷过程的影响展开研究,选用硫酸亚铁进行化学辅助除磷。药剂形成的化学污泥干扰生物除磷过程且成分复杂,故以磷酸铁、氢氧化铁模拟化学污泥,由钾离子、K/P摩尔比计算出同步除磷中的生物除磷,来探讨化学污泥对聚磷菌释磷/吸磷过程的影响。结果表明,连续投加硫酸亚铁使聚磷菌的释磷量、吸磷量降低;系统中磷酸铁含量0.075 mmol/L时聚磷菌的释磷和吸磷能力提高了约25%,磷酸铁含量0.15 mmol/L时对聚磷菌吸磷有抑制作用;氢氧化铁对聚磷菌释磷、好氧初期吸磷均有抑制作用。生物污泥与化学污泥存在交互作用。