Closed Form Solutions of the Two-Dimensional Turning Bands Equation

The turning bands method generates realizations of isotropic Gaussian random fields by means of appropriately summed line processes. For two-dimensional simulations the relation between the isotropic correlation function of the random field and the correlation function to be simulated along the lines is given by an integral equation of Abel type. We present closed form solutions of this integral equation for almost all two-dimensional correlation models encountered in practice and discuss their numerical implementation. As an additional benefit, our tables and illustrations serve as a concise guide to correlation models useful in geostatistics.     

钢、水泥需求“S”形规律的三个转变点剖析

本文剖析了人均钢、水泥消费“S”形轨迹的三个重要转变点, 论述了人均消费量和消费强度变化规律的影响因素和内在机制, 阐述了产业部门钢消费强度的倒“U”形轨迹, 在分析国内外经济结构演变趋势的基础上, 提出我国第二产业占GDP比例已经达到顶点, 指出钢、水泥消费强度顶点大小及到来的时间。     

Replacement of Dietary Fish Oil with Vegetable Oils Improves the Growth and Flesh Quality of Large Yellow Croaker （Larmichthys crocea）

We investigated the effect of the replacement of dietary fish oil with vegetable oils on the growth and flesh quality of large yellow croaker(Larmichthys crocea). The basal diet(FO) was formulated to contain 66.5% fish meal and 6.4% menhaden fish oil; whereas the other 3 experimental diets were formulated by replacing the fish oil with 50% soybean oil(SO50), 100% soybean oil(SO100) and 100% palm oil(PO100), respectively. The 4 diets were randomly assigned to 4 floating sea cages(3.0 m × 3.0 m × 3.0 m), and each was stocked with 250 fish individuals with an initial average weight of 245.29 g ± 7.45 g. The fish were fed to apparent satiation twice a day at 5:00 and 17:00, respectively, for 12 weeks. Experimental analysis showed that the specific growth rate of fish fed SO50 or PO100 were significantly higher than that of fish fed FO or SO100(P0.05), and crude lipid contents of ventral muscle and viscera were significantly lower in fish fed FO than in those fed the other 3 diets(P0.05). No significant differences in condition factor, viscerosomatic index, hepatosomatic index, gutted yield and colorimetric values of fish among the dietary treatments were observed(P0.05). Compared to FO diet, SO50, SO100 and PO100 diets led to substantial decreases in the liquid loss and water loss from fresh fillets(1 d, 4℃)(P0.05). Similarly, thiobarbituric acid reactive substance(TBARS) values of fillets under different storage conditions(1 d, 4℃; 7 d, 4℃; 4 weeks,-20℃; 8 weeks,-20℃) decreased significantly after partial or complete replacement of fish oil with vegetable oils. These findings indicated that the growth performance and selected flesh quality properties(liquid holding capacity and TBARS value) of large yellow croaker were substantially improved by replacing dietary fish oil with vegetable oils.     

2011年长江中下游旱涝急转及汛期暴雨的对流条件研究

利用ERA-Interim及雨量和土壤水分观测资料,对比诊断了2011年5—6月长江中下游梅汛前极旱期急转为梅汛期洪涝的极端天气事件的对流条件（水汽、不稳定、抬升作用）差异及特征,并研究条件性湿位涡垂直通量（CMF）指数与暴雨之间的定量关系。结果表明:在极旱期,干冷的东北气流控制,西太平洋副热带高压偏东,低层水汽通量弱且以偏北风输送为主,中低层为下沉气流,无低空急流,等θ_se线稀疏,边界层抬升机制缺乏,是干旱加剧的主要因子;在梅汛期,西南气流增强,西太平洋副热带高压西伸,低层气流在长江地区辐合,低层水汽通量增加且转为西南和东南风输送为主,伴随高低空急流耦合和深厚的上升运动,等θ_se线密集形成梅雨锋,增强不稳定暖湿空气强迫抬升和垂直输送,造成暴雨频发,引起区域性洪涝。暴雨中心600 hPa以下为负湿位涡的不稳定层,对流不稳定与条件性对称不稳定共同作用是强降水发生的不稳定机制。CMF指数与旱涝变化、暴雨过程演变非常一致,在极旱（梅汛）期,CMF指数低（高）,变化平缓（剧烈）,CMF指数在暴雨开始时逐步剧增,结束时迅速减小。      

基于人工降雨试验的淮北地区产流产沙差异性研究

针对淮北地区水土流失问题,利用野外人工模拟降雨试验,分析了不同雨强(40mm/h、60mm/h和80mm/h)和坡度(5°、10°和15°)条件下砂姜黑土和黄潮土产流产沙差异。结果表明:砂姜黑土初始产流时间长,产流总量小。坡面出现细沟时,砂姜黑土初始含沙量随时间变化有减小趋势,最终趋于稳定,而黄潮土含沙量呈波动变化;60mm/h、80mm/h雨强10°坡砂姜黑土产沙总量大于黄潮土,其他情况黄潮土产沙总量大于砂姜黑土,黄潮土土壤侵蚀严重。砂姜黑土表面细沟发育密度大,主要在坡面中下部,为相互连通的树枝状结构,而黄潮土表面细沟发育密度小,形成沟壑。两种土壤产流总量、产沙总量与坡度、雨强分别呈多元线性函数、多元幂函数关系,雨强对坡面产流产沙总量的影响大于坡度。     

黄河口减沙与流路稳定

黄河口的减沙与水资源利用是稳定黄河流路的重要措施。入海流路的选择是确保油田开发、港口建设和防灾的重要工作。加强河口港湾和河口治理工程的研究是解决黄河口治理的关键工程。     

The Correlation Bias for Two-Dimensional Simulations by Turning Bands

The turning bands method (TBM) generates realizations of isotropic Gaussian random fields by summing contributions from line processes. We consider two-dimensional simulations and study the correlation bias attributable to the use of only a finite number L of lines. Our analytical and numerical results confirm that the maximal bias is of order 1/L, and that L = 64 lines suffice for excellent covariance reproduction. The notorious banding observed in simulations with an insufficient number of lines is a related but different phenomenon and depends strongly on the choice of the line simulation technique. Clear-cut recommendations for the number of lines necessary to avoid the effect can only be based on practical experience with the specific code at hand.     

鄂尔多斯侏罗纪盆地形成演化和聚煤规律

鄂尔多斯盆地是在演太平洋构造域和特提斯构造域共同影响下形成的中生代大型内陆拗陷。其演化过程可分为早侏罗世-中侏罗世早期、中侏罗世、晚侏罗世和早白垩世4个阶段,旱侏罗世-中侏罗世早期为重要的聚煤期。聚煤区围绕盆地沉降中心呈环带状展布,煤层层数、厚度及横向变化规律在盆地不同部位表现出不同特点。构造转折期与有利于植物大量繁殖的古气候的有机匹配是控制煤层形成的主要因素。现今盆地范围是后期改造的结果。     

南黄海地震区的地震活动性研究

北纬３１°—３５°、东经１１９°—１２５°范围内的南黄海地震区,中强地震活动频繁,这主要是由一组北北东向和北西—北西西向共轭走滑活动断层及张性铲形活动断层引起的,该区内的中强震活动具有准周期性,震中呈东移趋势,区内地震在原地或同一构造部位重复发生的概率比较高,且空间分布是不均匀的,其中,海域地震强度明显高于陆域地震,在第Ⅲ、Ⅳ地震活跃期内,中强震主要发生在北纬３３°±１°、东经１２１°±１°所在的南黄海海域的南部盆地,本区第Ⅳ活跃期内中强地震的活动水平与近期内中小地震的活动水平相当,同时,海域地震还具有成丛性及５７ 年、６ 年的节律,地震震中具有南北迁移的特征     

蝉花菌质(Isaria cicadae)对大黄鱼(Larimichthys crocea)幼鱼生长、免疫和肠道菌群的影响

试验目的旨在研究蝉花菌质(Isaria cicadae)对大黄鱼(Larimichthys crocea)幼鱼生长性能、抗氧化和免疫、肠道组织形态以及肠道菌群等方面的影响,为大黄鱼绿色饲料添加剂的开发和利用提供参考。将初始体重为(16.50±1.10) g的大黄鱼幼鱼随机分成4组,对照组(IC0)不添加蝉花菌质,试验组分别添加1%(IC1)、3%(IC3)和5%(IC5)的蝉花菌质。试验结果表明:试验组的增重率(WGR)和特定生长率(SGR)显著高于对照组(P<0.05)。IC3与IC5组的肝体比(HSI)显著低于对照组(P<0.05),与IC1组差异不显著(P>0.05)。IC5组脏体比(VSI)显著低于对照组,但与其他试验组之间差异不显著(P<0.05)。肌肉和全鱼体成分各组之间差异不显著(P>0.05)。试验组肝脏过氧化氢酶(CAT)和血清溶菌酶(LZM)的活性显著高于对照组(P<0.05),各试验组间无显著性差异(P>0.05)。对照组单根绒毛杯状细胞数量显著少于各试验组(P<0.05),各试验组间无显著性差异(P>0.05...