大型结构物自动称重过程的计算机控制技术

大型结构物的称重通过多个千斤顶同步顶升实现。大型结构物往往存在柔度大、重量分布不均、支点跨距大的特点。在称重过程中需要进行计算机同步控制,实现结构物的平稳顶升和下降。大型结构物自动称重以工控机为核心,基于现场总线技术,对压力传感器、位移传感器、状态设置开关、油泵换向阀和油管超高压电磁阀等设备进行网络监控,对多个支点同步协调控制和结构物的精确称重,该系统已在多个油气田工程的建造中得到实际应用。     

A randomized controlled trial of a new fetal acoustic stimulation test for fetal well-being

OBJECTIVES: Our purpose was to determine (1) whether a fetal acoustic stimulation test results in more palpable fetal movement compared with a mock test (control) and (2) whether palpated fetal movements after a fetal acoustic stimulation test are accompanied by a reactive nonstress test. STUDY DESIGN: In a randomized controlled trial we studied women seen in the labor and delivery suite for various indications. Women were excluded for multiple gestation, < 31 weeks' gestational age, treatment with magnesium sulfate or narcotics, or ruptured membranes. Informed consent was obtained from eligible women, who were then randomized to a test or control group. We placed an acoustic stimulator on the abdomen of each woman, but only the test group was stimulated. We assessed fetal movement by a grading system: 0 = no fetal movement felt by patient or tester, 1 = fetal movement felt by patient only, 2 = fetal movement felt by tester, 3 = visual movement seen by tester. A positive fetal acoustic stimulation test result was defined as one with any fetal movement felt or seen by the tester (grades 2 or 3). We then performed a nonstress test. We compared rates of a positive fetal acoustic stimulation test in the test and control groups with the chi 2 test. A p value < 0.05 was considered significant. RESULTS: We randomized 297 women to the test group and 280 women to the control (mock test) group. Of women tested with the fetal acoustic stimulation test. 81% had fetal movement by palpation or visualization (grades 2 or 3) compared with 19% of the control group (p < 0.0001, odds ratio 19.29, 95% confidence interval 12.42 to 30.07). Of the test group, 283 (95%) had a reactive nonstress test and 14 (5%) had nonreactive tests; the control group had 267 (95%) reactive and 13 (5%) nonreactive nonstress tests. Of 242 patients in the test group with a positive fetal acoustic stimulation test, 236 (98%) had a reactive nonstress test. Of those in the test group with fewer than three contractions per 10 minutes. 164 (89%) had a positive fetal acoustic stimulation test. Of these, 162 (99%) had a reactive nonstress test. CONCLUSION: The fetal acoustic stimulation test evokes significantly more palpated or visualized fetal movement than in controls. Palpated or visualized fetal movement after acoustic stimulation was almost always accompanied by a reactive nonstress test.     

微光CCD摄像器件综合特性的分析与比较

ＣＣＤ的优良特性使其在微光电视技术领域得到了广泛运用。本文对各种微光ＣＣＤ摄像器件的综合特性例如信噪比、探测率、动态范围与计数模式等进行了详细的研究与对比，并得出基本结论。     

聚丙烯共混表面改性剂的研究

由不同链长的甲基丙烯酸长链醇酯。少量改性剂与聚丙烯共混，能大幅增加聚丙烯表面润湿性与粘接性，而拉伸强度与熔点却变化不大。通过ＥＳＣＡ与接触角分析，发现极性基团大表面富集，添加不同改性剂使材料表面富集的极性基浓度与粘接强度产生差异。     

Cigarette smoking and submaximal exercise test duration in a biracial population of young adults: the CARDIA study

Symptom-limited, graded exercise treadmill testing was performed by 4,968 white and black adults, ages 18-30 yr, during the baseline examination for the Coronary Artery Risk Development in Young Adults (CARDIA) study. Compared with nonsmokers, the mean exercise test duration of smokers was 29-64 s shorter depending on race/gender group (all P < 0.001), but mean duration to heart rate 130 (beats.min-1) ranged from 20-50 s longer (P < 0.05). In each race/gender group, test duration to heart rates up to 150 was 15-35 s longer (P < 0.05) in smokers than in nonsmokers after adjustment for age, sum of skinfolds, hemoglobin, and physical activity score. The mean maximum heart rate was lower in smokers than in nonsmokers (difference ranging from 6.7 beats.min-1 in white men to 11.2 beats.min-1 lower in black women, P < 0.001), although maximum rating of perceived exertion was nearly identical in smokers and nonsmokers. Chronic smoking appears to blunt the heart rate response to exercise, so that exercise duration to submaximal heart rates is increased even though maximal performance is impaired. This may result from downloading of beta-receptors caused by smoking. Smoking status should be considered in the evaluation of physical fitness data utilizing submaximal test protocols, or else the fitness of smokers relative to nonsmokers is likely to be overestimated.     

Chimpanzee (Pan troglodytes) pointing: hand shapes, accuracy, and the role of eye gaze

We have validated a new semiautomated method for quantification of volumetric flow applied to multiplane transesophageal color Doppler mapping. This Doppler technique assumes only the incompressibility of the fluid and includes variations of flow area. By computing velocity vectors across a surface normal to the point of scanning, volumetric flow can be measured independently of the angle of incidence between the ultrasonic beam and the direction of blood flow. Mitral valvular flow rate was measured during surgery by transesophageal color Doppler echocardiography in 27 patients undergoing coronary artery bypass grafting at 45 sets of observations. The results were compared with those obtained by the thermodilution technique. The mean of the differences between the thermodilution technique and color Doppler echocardiography was 0.06 +/- 0.866 L/min for the mitral valvular flows (mean of differences [thermodilution-color Doppler] &/- 2 SDs of differences). Thus mitral valvular volumetric flow measured by this color Doppler method showed a close agreement to the thermodilution technique during surgery.     

液态烃球罐安全应用探讨

液态烃常温球罐储存技术相当成熟,但在实际应用方面仍然存在许多问题,影响安全储存。针对使用过程中所了解的一些具体做法进行了分析和探讨,对球罐的改造和设计提供了必要的参考。