准噶尔盆地乌夏地区稠油稠变阶段及其成藏特征分析

乌夏地区稠油分布于距油源玛湖凹陷远距离的断裂上盘中生界超覆尖灭带上,埋深浅,构造简单。表现出高密度、高粘度、高沥青质、高酸值、低蜡、较高凝固点的特征,体现了生物降解原油的基本特征。根据其饱和烃色质谱特征、生物标志化合物降解程度、三环萜烷和孕甾烷含量等将其降解稠变过程划分为4个阶段。长距离通过不整合面运移遭受水洗、生物降解是导致原油稠变的主要因素,其成藏主要与不整合和浅部正断层有关,在后期成藏中对油气有重要的封堵作用。     

视觉文档图像中反渗噪声的去除方法

提出根据直方图特征去除视觉文档图像反渗噪声的方法.对于灰度直方图呈双峰特性的噪声图像,选取适当区域分别进行增强或归一化处理以达到去除反渗噪声的目的;而对于直方图呈单峰特性的含反渗噪声图像,建立了一种基于背景分离的新算法.实验结果表明,该方法可以有效去除视觉文档图像中的反渗噪声.     

一种新的基于相位调制跟踪的电源并联控制方法

研究了抗干扰能力强、控制可靠性高的数字化并联控制技术，提出了一种数字均流控制方法一相位调制跟踪法。该方法将每个模块有功功率、无功功率和同步信号通过相位调制的方法变换为相位变化的周期脉冲信号，然后通过锁相同步的方法使所有并联逆变器模块都跟踪相位最超前，即输出功率最大模块的脉冲信号，从而实现功率均分。该方法具有控制信号分辨率高，抗干扰能力强以及稳定性好等优点，提高了系统均流控制精度；同时，自然实现了民主主从控制，具有好的控制冗余性。克服了线路阻抗变化对系统均流精度的影响。实验结果表明，该方法能较好地实现逆变模块的功率均分，模块间输出电流偏差小于1％。     

Comparison of left anterior oblique, anterior, and geometric mean methods in gastric emptying assessment of postpancreaticoduodenectomy patients

Although left anterior oblique (LAO) gastric emptying studies appear to be an adequate alternative to geometric mean (GM) measurements in patients with normal gastric anatomy, it is not clear whether they can be used after gastric or duodenal surgery. In this study, dual-phase gastric emptying studies with combined solid-liquid meal were performed in 54 patients who had undergone pancreaticoduodenectomy (Whipple procedure). Gastric emptying was studied with GM, LAO, and anterior (ANT) methods. T1/2 and percent gastric retention at 10, 30, 60, 90, and 120 minutes were calculated. Results from the three methods were compared using correlation analysis and the t test. The t test showed no significant difference in T1/2 and percent retention values between the GM and LAO or ANT views. The solid emptying T1/2 showed a better correlation between GM and LAO values (r = 0.824) than between GM and ANT (r = 0.589). For the liquid T1/2, the reverse was true. Correlation between GM and ANT (r = 0.939) was better than between GM and LAO (r = 0.839); however, both LAO and ANT views correlated well with GM liquid emptying. It is concluded that the LAO view can replace GM gastric emptying methods in postpancreaticoduodenectomy patients for evaluation of both solid and liquid emptying, although the ANT view appears completely adequate for the study of liquid emptying.     

Learning differential diagnosis of erythemato-squamous diseases using voting feature intervals

A new classification algorithm, called VFI5 (for Voting Feature Intervals), is developed and applied to problem of differential diagnosis of erythemato-squamous diseases. The domain contains records of patients with known diagnosis. Given a training set of such records, the VFI5 classifier learns how to differentiate a new case in the domain. VFI5 represents a concept in the form of feature intervals on each feature dimension separately. classification in the VFI5 algorithm is based on a real-valued voting. Each feature equally participates in the voting process and the class that receives the maximum amount of votes is declared to be the predicted class. The performance of the VFI5 classifier is evaluated empirically in terms of classification accuracy and running time.     

Small-dose hyperbaric versus plain bupivacaine during spinal anesthesia for cesarean section

In a double-blind, randomized trial, 98 parturients undergoing cesarean section received either hyperbaric or plain bupivacaine 6.6 mg combined with sufentanil 3.3 microg as part of a combined spinal-epidural procedure. To prevent hypotension, 1000 mL of lactated Ringer's solution, 500 mL of hydroxyethyl starch 6%, and ephedrine 5 mg were administered i.v. The height of the block was equal in both groups, but more patients in the plain group had blocks that were either too high or too low (P < 0.01). The number of patients requiring epidural supplementation was equal in both groups. Strict criteria were used to treat hypotension. The overall incidence of systolic blood pressure (<90 mm Hg) was 13%, whereas it was more pronounced in the plain group (21% vs 6% in the hyperbaric group, P < 0.05), which required more ephedrine (P < 0.05) and in which a greater incidence of nausea was noticed (P < 0.05). We conclude that the use of a small dose of intrathecal bupivacaine combined with sufentanil plus our described preloading regimen resulted in a lower incidence of hypotension. Further, we conclude that the use of hyperbaric bupivacaine in this manner provides a more reliable block and a lower incidence of hypotension than plain bupivacaine. Implications: A small dose of hyperbaric bupivacaine 0.5% combined with sufentanil used intrathecally during cesarean section offered a more reliable cephalad spread of the spinal block than the glucose-free combination, which was reflected in a lower incidence of hypotension and nausea.