宁夏及其邻区背景噪声能量来源方位及强度的季节性变化分析

由背景噪声互相关重建格林函数的技术已在地震学中得到了广泛应用,对背景噪声能量的空间分布、强度的季节变化的研究有利于认识噪声互相关函数对格林函数的收敛性.文中利用宁夏及其周边地区33个宽频带台站2008年1月至2012年11月垂直分量的连续记录,计算了两两台站间的互相关函数,并对该地区5～ 10s及10～20s的背景噪声能量的优势方位及强度随季节的变化进行了分析.结果表明,5～10s的能量主要来自于中国东部的海岸线,其强度具有明显的季节性变化；10～20s的噪声能量不仅强度具有季节性的变化,其优势方向也随季节具有明显变化,受到多个大洋的交替影响.研究表明,宁夏及其邻区的背景噪声场具有较为复杂的特征,在进行后续研究时要予以充分考虑.

Performance of Moroccan Wheat Cultivars under Tillage Systems and Water Regimes

The superiority of wheat grain yield under no-till has been reported by many authors, and others reported significant interaction between wheat cultivar and tillage system for grain yield and other related traits. Hence, new breeding initiatives are needed to introgress favorable traits into wheat and other crops in areas where no-tillage is being adopted. The identification of such traits is solely possible via the assessment ofgermplasm under no-tillage. Moreover, Moroccan wheat breeding programs are carried out solely under conventional tillage system whilst the conservation one is becoming widely adopted. So, the ultimate objective of this research is to find out if the used wheat commercial cultivars behave differentially under no tillage system and to propose the use of appropriate cultivars for the appropriate tillage system and to implement a breeding program specifically for no tillage system. The experiment has been carried out during 2006-2007 at Douyet （F6s）. Cultivars have been sown according to a strip-split plot design. At maturity, yield, yield components and related traits have been recorded. The results indicated that both water regime （WR） and variety （Vat） had a highly significant effect on all measured traits. In contrast, tillage system （TS） had similar effect on yield, grains m-2, biomass, and plant height, but had no effect on harvest index, 1000-kernel weight and heading date. The TSxVar interaction has been significant to highly so on all traits except on heading date. The magnitude of the interaction for grain yield was more important under irrigated treatment than under rainfed one. On the whole, No Tillage yielded more grains than conventional one. Moreover, Achtar and Areal （bread wheat cultivars） and Marjana and Marzak （durum wheat cultivars） yielded more under No-Till. The significant interaction between TS and Var paves the way for the implementation of a breeding program under no till system.

采动效应微震特征及其变化规律

依据采动应力是煤与瓦斯突出的外在动力,构建煤巷采动微震监测系统,分析煤壁崩落过程及其诱因,研究顶板、煤壁破裂微震动态响应特征,了解采动应力显现、调整变化规律。优选小波基函数,按照频率顺序将半小时内396次采动效应触发的微震事件进行小波包4层分解、重构;根据采动顺序和信号优势频带,将采动微震响应信号划分为爆破、煤壁崩落、顶板和煤壁破裂4类信号,采用归一化频带能量分析顶板、煤壁破裂事件的变化趋势。爆破冲击和顶板压力导致煤壁崩落,顶板压力还会导致煤壁破裂,顶板和煤壁破裂是煤巷采动应力的具体显现。顶板压力初期显现剧烈,爆破结束1.6 s内煤壁发生5次崩落,1.933 s时达到峰值、24.89 min趋于稳定;顶板破裂事件主要集中在初期2 min内,相应的事件率为76.2%。煤壁压力滞后顶板压力5.8 s后显现,3.71 min后达到峰值、29.217 min稳定;煤壁破裂事件主要集中在初期5 min内,相应的事件率为45.9%。顶板、煤壁破裂事件及其优势频带能量变化趋势揭示采动应力转移、调整过程,采动效应稳定与否可用于煤与瓦斯突出预警,并值得进一步深入研究。