PCVSAT单收站的维护及故障处理

PCVSAT单收站是地县气象台站新一代气象信息网络平台,其肩负着下行资料的收集及接收多媒体广播信息的重任。PCVSAT小站的运行状态,将直接影响到气象资料的收集及其它服务,因此PCVSAT的稳定运行和日常维护就显得相当重要,本文就日常维护和故障处理谈一些经验,以达到更好地保证业务工作顺利运行的目的。     

FY-3B/VIRR海表温度算法改进及精度评估

该文介绍了卫星观测海表温度 (SST) 算法的发展历程,给出了所用SST算法的回归模型,并在FY-3B/VIRR业务SST算法的基础上进行了改进。基于NOAA-19/AVHRR匹配数据集,进行多算法建模分析及精度评估,白天最优算法为非线性SST (NL) 算法,夜间最优算法为三通道SST (TC) 算法,最优算法的确定与NESDIS/STAR一致。建立2012年8月—2013年3月FY-3B/VIRR匹配数据集,并在此基础上进行多算法回归建模及精度评估,白天和夜间的最优均为NL算法,分析发现夜间TC算法采用匹配数据集版本2(MDB_V2) 时,3.7 μm通道存在类似百叶窗的条带现象。以2012年10—12月FY-3B/VIRR匹配数据集计算回归系数,以2013年1—3月独立样本进行精度评估,与浮标SST相比,NL算法白天和夜间的均方根误差分别为0.41℃和0.43℃。与日平均最优插值海温 (OISST) 相比,NL算法白天和夜间的均方根误差分别为1.45℃和1.5℃; 选择与OISST偏差在2℃以内的样本,NL算法白天和夜间均方根误差分别为0.82℃和0.84℃。     

Vaisala AviMet系统中跑道视程RVR计算因子分析

对跑道视程RVR(Runway Visual Range)算法及其计算因子照度阈值(E)和灯光光强(I)的估值方式进行了归纳,对Vaisala AviMet系统在RVR数值计算中E和I的估值方式是否符合国际民用航空组织ICAO(International Civil Aviation Organization)公约《国际航空气象服务》进行了研究,通过对3个机场Vaisala AviMet系统的RVR历史数据进行演算、反推、比对等方法,最终推断出Vaisala AviMet系统中跑道视程RVR计算因子E和I的实际估值方式,并得出以下结论:Vaisala AviMet系统在进行RVR计算时,照度阈值E的估值并没有依据ICAO Doc 9328的推荐公式;无论塔台输出的灯光光强等级实际为多少,Vaisala AviMet都采用灯光光强等级为10%,对应I值为1000cd的固定值进行RVR计算。     

长江中下游地区1988—2010年遥感土壤湿度的时空变化

利用农业气象站观测资料对长江中下游地区1988-2010年遥感土壤湿度进行了验证,并与NCEP和ERA-Interim土壤湿度做了对比分析。研究表明,ECV遥感土壤湿度冬季平均土壤湿度最高,春季和秋季次之,夏季平均土壤湿度最低;这种季节性干湿变化与农业气象站观测资料一致。但是,NCEP和ERA-Interim土壤湿度再分析资料,则夏季平均土壤湿度高,春季和秋季次之,而冬季平均土壤湿度最低;这种季节性变化与ECV遥感土壤湿度和农业气象站观测资料呈反位相。就年际变化而言,ECV遥感土壤湿度与农业气象站观测资料和两套再分析资料均有较高的一致性,并在春季和秋季最高,尤其是在长江以北地区和长江以南洞庭湖、鄱阳湖两大湖区,相关系数达到0.7~0.9;而夏季一致性最低,相关系数仅为0.4左右。在研究时段,ECV土壤湿度在冬季明显增加,在夏季则有明显下降趋势。     

基于双折减系数法的土坡稳定性分析

基于强度折减原理的土坡稳定性分析中,对土体的抗剪强度指标c、φ采用不同的折减系数进行强度折减,较传统的强度折减法更符合土坡的失稳破坏机制。为了进一步探讨双折减系数法在土坡稳定性分析中的具体应用,编制了基于FLAC-3D和双折减系数法的土坡稳定性分析程序,该程序可求解出能使土坡折减至极限平衡状态时的不同折减系数组合。利用该程序对2个典型土坡进行稳定性分析,并将土坡安全系数的计算结果与传统的强度折减法和简化Bishop法进行对比分析。算例分析表明:双折减系数折减法能体现出不同土体的抗剪强度衰减特性的差异;双折减系数法中SRFmin(c、φ折减系数平均值的最小值)与另外两种方法求解的土坡安全系数很接近,建议采用SRFmin作为土坡的安全系数。     

Torsion design implications from shake‐table responses of an RC low‐rise building model having irregularities at the ground story

A 1:5 scale five‐story RC building model having the irregularities of a soft/weak story and torsion at the ground story was subjected to a series of earthquake simulation tests. The test results reveal the following: The eccentricity varied from zero to infinity with the values of base shear and torque bounded by some limits. As the intensity of table excitations increased, representing earthquakes with return periods from 50 to 2500 years in Korea, the range of eccentricities at the peak values in the time histories of drift and base shear decreased from approximately ±30% to within ±10% of the transverse dimension of the model. The inertial torque was resisted by both longitudinal and transverse frames, in proportion to their instantaneous rigidity. Yielding of the longitudinal frames under severe table excitations caused a substantial loss in their instantaneous torsional resistance and thereby transferred most of the large torque to the transverse frames, resulting in a significantly degraded torsional stiffness with an enlarged torsional deformation despite almost zero eccentricity. From these observations, it is clear that the eccentricity in itself cannot represent the critical torsional behaviors. To overcome this problem, the demand in torque shall be determined in a direct relationship with the base or story shear, given as an ellipse constructed with the maximum points in its principal axes located by the two adjacent torsion‐dominant modal spectral values. This approach provides a simple but transparent design tool by enabling comparison between demand and supply in shear force–torque diagrams. Copyright © 2014 John Wiley & Sons, Ltd.     

历史地震资料在核动力工程地震安全性评价中的应用

以三个核工程安全性评价为例,论述了运用历史地震及其资料对在核工程厂址近区域发生地震的确认及其对厂址的影响;区域范围内大震震中区的确认;对ＳＬ－２估计以及历史地震在ＳＬ－２确定的原则,历史地震资料在ＳＬ－２确定的不确定性中的应用。     

新疆吐克吐克铜矿黄铜矿Re-Os定年及成矿意义

吐克吐克铜矿为笔者新发现,产于新疆西准噶尔构造带南部,成矿时代尚缺乏精确的同位素年代学制约。该矿床硫化物组合单一,主要为黄铜矿。本文选择了8件黄铜矿样品,进行Re-Os法定年。结果得到了较好的效果,所有样品的Re含量为39.7×10~(-12)~2440.6×10~(-12),~(187)Os含量为1.2×10~(-12)~9.0×10~(-12),给出的等时线年龄为288.3±8.8Ma。这表明该区Cu的成矿作用与晚石炭世—早二叠世区域峰期岩浆活动一致,证实该区仍存在较大找矿空间。     

陕南特长公路隧道水压致裂法地应力测量结果及工程地质意义分析

中国西部地区地势复杂,区域构造应力场各向异性显著,了解地区地壳应力状态是判断隧道设计阶段线路布设合理性的基础,也是预测隧道施工过程可能出现岩爆、断层滑动等其他工程灾害的重要参数。为了研究陕南特长高速公路隧道现今地应力状态,基于古仙洞隧道钻孔(ZK10钻孔)与化龙山隧道钻孔(ZK11钻孔)水压致裂地应力测量,获得了两隧道现今地应力分布特征。古仙洞和化龙山特长深埋隧道最大埋深处SH值分别为13 MPa和22 MPa;古仙洞与化龙山隧道的应力关系分别为SH>Sh>Sv和SH>Sv>Sh,水平主应力起主导作用;SH方向为近北西—北西西向,与区域现今构造活动背景基本一致,主要受秦岭造山带活动断裂影响。基于地应力测量结果、相关理论及判断依据认为：最大水平主应力方向与洞轴线夹角,有利于隧道围岩稳定,研究区内古仙洞与化龙山隧道的总体布置是合理的;采用岩石强度应力比法、陶振宇判据、Russenes判据和岩石应力强度比法综合判定研究区内两隧道不具备发生中等强度以上等级岩爆的可能;利用莫尔-库伦准则及拜尔定律,摩擦系数μ取0.6~1.0,对研究区内两隧道的现今地应力状态分析后发现,两隧道附近断裂带的地应力大小未达到地壳浅部断层产生滑动失稳的临界条件,处于较稳定的应力状态。     

Sex Offender Residential Movement Patterns: A Markov Chain Analysis

This article introduces a new approach to the analysis of changes in sex offender residences over time. Using a Markov chain framework, we analyze residential movement patterns of registered sex offenders in Hamilton County, Ohio, over a three-year period (2005–2007). Results indicate a 46 percent reduction in offenders violating spatial restriction zone policy as compared to a counterfactual case where offenders move as a function of housing distributions. Strong legacy effects are also found as offenders previously in violation of restriction policies move into other restricted zones at a higher rate than offenders who were previously in compliance with the policy. Parcels that previously were home to registered offenders also continue to attract offenders in future periods. Although we find differences in the probabilities of attracting offenders for parcels outside and inside restricted zones that are consistent with offender restrictive policies, these differences are actually significantly smaller than what holds under the counterfactual. Parcels in restricted zones continue to attract offenders at a higher rate than expected, despite the policy restrictions.