开江—梁平海槽东侧长兴组台缘生物礁发育特征及油气地质勘探意义

四川盆地开江—梁平海槽东侧已发现普光、黄龙场等大气田,是礁滩重要的勘探领域。为了进一步明确海槽东侧长兴组台缘生物礁发育特征,利用钻井、地震资料,以台缘生物礁外部轮廓、内部形态、平面展布为基础,开展海槽东侧台缘带、台缘生物礁发育特征研究。研究结果表明,开江—梁平海槽东侧台缘依据坡角差异性可划分为陡坡型和缓坡型,平面上具有分段特征,且发育缓坡退积型和陡坡叠加型两种模式,以缓坡退积型为主;台缘生物礁发育主要受海平面变化、同沉积多级断裂及区域拉张共同作用;缓坡台缘生物礁发育经历微古地貌形成期(吴家坪晚期)、缓坡滩发育期(长一期)、弱镶边台缘礁滩发育期(长二早期)、镶边台缘多排礁滩发育期(长二中期—长三期)4个演化阶段。开江—梁平海槽东侧长兴组缓坡多排礁分布面积广,油气成藏条件优越,是天然气勘探值得关注的重要领域。     

Biased motion-adaptive temporal filtering for speckle reduction in echocardiography

Describes a new fully motion-adaptive spatio-temporal filtering technique to reduce the speckle in ultrasound images. The advantages of this approach are demonstrated in echocardiographic boundary detection and in comparison with other techniques. The first stage of many automated echocardiographic image interpretation schemes is filtering to reduce the amount of speckle noise. The authors show how the two-dimensional least mean squares (TDLMS) filter can be configured as a motion-compensated filter for a time sequence of ultrasound images that eliminates the blurring associated with direct averaging. For an image corrupted by multiplicative speckle noise, the mode of the intensity distribution approximates the maximum likelihood estimator. In consequence, the temporal filter's output is biased towards the mode from the mean, using information contained within the speckle itself. A new adaptive algorithm for controlling the filter's convergence is also included. To evaluate performance, application to simulated, phantom, and an in vivo test sequence of the carotid artery are considered in comparison with other techniques. The effect of filtering on edges is of great importance, as these are used by subsequent image interpretation schemes. Quantitative measurements demonstrate the effectiveness of the Biased TDLMS filter, for both noise reduction and edge preservation. Echocardiographic images have a high noise content and suffer from poor contrast. Despite this challenging environment, the Biased TDLMS filter is shown to produce images that are better inputs for subsequent feature extraction. The benefits for echocardiographic images are highlighted by considering the problems of mitral valve analysis and extraction of the left atrium boundary.     

巧用PowerBuilder编程整理表结构文档

使用PowerBuilder开发应用程序的人可能都有这样的体会:当一个项目开发完成之后,文档的整理是项工作量很大的任务。其中,表结构的整理就颇为费事。当初设计的表结构很可能在项目进展过程中有所修改或补充,由于开发人员的、有时甚至还有用户的各种各样的原因,经常造成程序和文档不能同步修改,产     

对TLS1B高频距离保护的阻抗元件的动作特性分析

通过对ＴＬＳ１Ｂ高频距离保护的各阻抗元件的动作方程的推导,分析了它们的暂,稳态动作特性,及极化电压对特性的影响,并阐明了各阻抗元件的具体试验方法和公式。     

小波理论用于交流伺服进给系统的观测控制

讨论了小波理论应用于控制领域的可能性,通过对交流同步电机驱动的半闭环伺服系统进行的仿真研究证明,交流同步电机电磁转矩的二阶或三阶小滤变换对末端速度的变化比电磁转矩本身更为敏感,根据电磁转矩的二阶或三阶小波变换极大模值的幅度稠度,可以识别出速度变化的起始时间、终止时间和变化幅度。     

用排序网实现ATM信元淘汰

本文探讨了修改排序网实现信元淘汰的方法（简称Ｂ网）。比较了Ｂ网和［１］中淘汰网（简称Ｋ网）的复杂性和时延。给出了集线比λ＝Ｌ／Ｎ的临界值λ０（Ｎ），并证明当λ＞λ０（Ｎ）时Ｂ网有较小复杂性和较小时延。     

Limitations of the lead oxide vidicon for dual-energy digital subtraction angiography

Dual-energy digital subtraction angiography (DSA) can be performed, with some modifications, using existing systems designed for conventional DSA work. However, the video camera generally found in such installations, the lead oxide vidicon, places significant limitations on the image quality of dual-energy DSA. If the video camera is operated in a 60 Hz, 266 line progressive scanning mode to maintain a nominal 30 subtraction images/s frame rate, the maximum available X-ray pulse width is limited to 5 ms. The resulting required increase in low-energy kVp reduces the dual-energy signal-to-noise ratio by approximately 40% for cardiac dual-energy DSA imaging. In addition, the performance of the video camera with respect to read-out lag is much more important for dual-energy DSA than conventional single-energy imaging. Measurements show that lag reduces the iodine contrast in dual-energy DSA by up to 20% when a 30 Hz vertical scan mode is used, and by up to 27% when a 60 Hz vertical scan mode is employed. Replacement of the lead oxide vidicon with a CCD camera removes these limitations.     

基于多井模型的压裂参数-开发井距系统优化

以变缝宽导流裂缝为基本流动单元,建立考虑井间干扰和缝间干扰的多水平井渗流数学模型,采用半解析方法求解模型,模拟多井开发平台全生命周期生产动态,分析裂缝长度、裂缝导流能力、井距、缝距等因素对生产效果的影响。在此基础上提出了以压裂规模为内部约束条件,以经济效益为外部约束条件的"嵌套式"全局优化方法来优化水平井-裂缝等钻完井参数。研究表明,不考虑约束条件时,增加裂缝与地层接触面积、降低缝/井间干扰强度、平衡裂缝与地层流入流出关系均能有效提高平台开发效果,但不存在最优钻完井参数。仅考虑内部约束条件时,存在最优裂缝导流能力和长度,但不存在最优井距、缝距。同时考虑内外部约束条件时,裂缝导流能力、裂缝长度、井距、缝距等因素间产生关联,出现参数优化空间,在压裂规模较小时宜采用小井距、宽缝距、短裂缝的水平井部署模式;在压裂规模较大时则宜采用大井距、窄缝距、长裂缝的部署模式。图14参28     

多尺度体积压裂支撑剂导流能力实验研究及应用

裂缝有效导流能力是评价压裂施工效果的主要参数,也是影响压裂增产效果的最重要因素之一。设计了多尺度裂缝导流能力实验方法,采用单一粒径和组合粒径的铺置方式,研究了闭合压力、粒径组合方式、铺砂浓度及应力循化加载条等因素对多尺度主裂缝及分支缝内支撑剂的导流能力变化的影响。实验研究结果表明:随着闭合压力增加,大粒径支撑剂与小粒径支撑剂的导流能力差距逐渐变小,主裂缝及分支缝内支撑剂导流能力逐渐降低,而且这种降低趋势存在明显的转折点。组合粒径铺置条件下,主裂缝及分支缝内支撑剂组合均存在最优的组合方式。主裂缝及分支缝内支撑剂铺置砂浓度越高,导流能力也越高;随着闭合压力增大,高浓度铺砂与低浓度铺砂条件下的导流能力差距逐渐变小。应力加载破坏对支撑剂导流能力的影响是不可逆的。现场应用表明,在满足压裂工艺要求前提下,通过支撑剂组合方式及加砂方式的合理优化,可有效提高裂缝导流能力及压后产量。研究结果为体积压裂方案优化及现场施工提供基础数据依据。