A generalized gamma distribution with application to drought data

Gamma distributions are some of the most popular models for hydrological processes. In this paper, a very flexible family which contains the gamma distribution as a particular case is introduced. Evidence of flexibility is shown by examining the shape of its probability density function (pdf). A treatment of the mathematical properties is provided by deriving expressions for the n th moment. Estimation and simulation issues are also considered. Finally, a detailed application to drought data from the State of Nebraska is illustrated.     

矿用圆环链弯曲点的角度分布

矿用圆环链弯曲点是应力集中点 ,肩部断裂发生于该点附近 .以 2 6× 92矿用圆环链为研究对象 ,应用方向数据统计导出该点的角度分布 ,并给出了批量检验矿用圆环链尺寸匹配状况的一种方法     

大庆油田杏1-3区三次加密试验区剩余油分布研究

通过对试验区近年完钻的检查井各单砂层水淹状况及其影响因素的分析。利用神经网络模式识别方法建立起单层剩余油识别模型，在此基础上对三次加密试验区各小层剩余油分布进行研究，总结出各类油层剩余油分布特征及成因类型，并分析了试验区剩余油潜力分布，从而为三次加密布井及射孔方案编制提供了可靠的依据。     

有扰对称信道平均信息量的计算

照相手机让诺基亚抢了风头，这真是亚洲人的失策。在日本和韩国，内置摄像头的手机早就不是什么值得炫耀的东西了。不过日本人的动作还是很快的，GD88和N8一副后来居上的架势，让人不敢小瞧。     

明渠湍流床面附近跃移层面颗粒浓度垂线分布

本文以动理学理论的Boltzmann方程为基础，考虑明渠湍流床面附近猝发喷射和清扫运动对跃移层内运动颗粒的不同作用，分析了明渠中泥沙颗粒浓度垂线分布问题，得到了适用于包括跃移层、悬移层在内的统一浓度垂线分布公式。文中着重研究了跃移层内运动颗粒的浓度垂线分布，并将本文结果与实测跃移层内浓度垂线分布及实测跃移层顶部浓度进行了对比，结果表明理论与实验两者符合较好。     

Recent developments of high-performance NEOMAX magnets

For further improvement in achieving extremely high magnetic properties of Nd- Fe- B sintered magnets, extensive investigation has been done to densify the magnet up to the theoretical value, to increase the volume fraction of the Nd ₂Fe₁₄B matrix phase, and to achieve a high degree of alignment. By controlling chemical composition and the amount of constituent phases,improving particle size distribution, and adopting the isostatic pressing method to get better alignment of fine particles, we have succeeded in obtaining a high-performance magnet having residual flux density (B_r) of 1.495 T (14.95 kG), maximum energy product [(BH)_max] of 431 kj/m³ (54.2 MGOe), and intrinsic coercivity (iH_c) of 845 kA/m (10.62 kOe).     

Differentiation between epigeic and hypogeic fauna in gravel streams

The ‘hyporheic zone’ is described. According to the classical definition, water below the sediment surface is groundwater and the hyporheic interstitial zone is part of the phreatic system. This ignores the vertical distribution of the epigeic benthic fauna. The uppermost layer of the sediment (bed sediments) of the hyporheic zone is dominated by epigeic faunal elements and is therefore part of the surface system. In contrast to hypogeic species, the depth penetration of epigeic species is limited. Possible explanations are discussed.     

Influence of heat transfer on anodic oxidation of aluminium

The influence of convective heat transfer on constant current density anodizing of aluminium in sulfuric acid has been examined in a wall-jet electrode reactor. The uniformity of the anodic film thickness is related to the local electrode temperature distribution, which is dependent on the convection. The higher the local temperature, the greater the local oxide thickness. An increased local temperature enhances local field assisted oxide dissolution at the pore bases, and consequently acts to increase the local current density. At relatively high current densities, local features develop on the electrode surface, accompanied by high initial, local temperature rises. The relevance of such local features, limiting useful oxide growth, is considered further.     

太阳能热风发电技术研究进展

介绍了太阳能热风发电的产生背景、技术原理和特点。太阳能热风发电能够实现由太阳能到空气动能,最终到电能的转变,具有环保无污染、运行维护简单、缓解常规能源消耗等特点。简要介绍世界上第1座试验性质的太阳能热风发电站。对太阳能热风发电技术相关研究历程从试验研究和理论研究2个方面做了综述,重点介绍了澳大利亚电站的建设进展及最新相关学术研究进展,包括过渡段理论及试验研究、系统数值模拟和太阳能热风发电技术在高山地区的应用等。介绍我国太阳能资源情况,指出我国太阳能资源丰富,适合建造大型太阳能热风发电站。