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Zeng Xin Xin Mingdao 《保鲜与加工》1991,(6):8-14
An implicit enthalpy solution is developed for analysis of one-dimensional conduction controlled phase change problems. The solution is based on separating the sensible and latent heat terms in an enthalpy formulation. By making the assumption of equal volume node-jumping,a variable time together with a fixed space grid is used to ensure that the phase boundary is always on a node point,so that the nonlinearity associated with the latent heat can be effectively dealt with via the source term. A freezing problem around a pipe with analytical solution is applied to demonstrate the effect of the present method. 相似文献
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ObjectivesTo define electrocardiographic features of complete left bundle branch block (LBBB) and right bundle branch block (RBBB), and the use of R-peak time (RPT) to identify interventricular dyssynchrony in dogs with BBB.Animals, materials and methodsTwelve-lead ECG tracings of 20 dogs with RBBB, 20 with LBBB, and 60 healthy dogs were retrospectively analyzed and RPT was measured in precordial leads. Interventricular dyssynchrony index (IDI) was than calculated.ResultsIn RBBB, mean electrical axis (MEA) was −111° [−120/−100°], V1RPT was significantly longer (61 ms [55–72 ms]) than left precordial leads RPT (V2:25 ms [22–30 ms]; V3:25 ms [22–29 ms]; V4:24 ms [21–29 ms]; V5:25 ms [22–29 ms]; V6:25 ms [22–29 ms]) and when compared to normal dogs (P < 0.001). In LBBB, MEA was 76° [70/81°], RPT in left precordial leads was significantly longer (V2:49 ms [34–58 ms]; V3:49 ms [43–57 ms]; V4:52 ms [45–62 ms]; V5:53 ms [45–63 ms]; V6:55 ms [45–63 ms]) than V1RPT (17 ms [15–20 ms]) and when compared to normal dogs (P < 0.001). V1RPT > 28 ms and V5RPT > 36 ms were found to predict the presence of RBBB and LBBB with a sensitivity of 100% and 96.7%, and a specificity of 96.7% and 99.5%, respectively. The IDI was 23% [16–29%] in normal dogs and significantly greater in dogs with RBBB (33% [30–38%]; P < 0.001) and LBBB (32% [23–41%]; P = 0.006).ConclusionsThis study defines ECG features and RPT in dogs with BBB. Electrical interventricular dyssynchrony can be defined using IDI in dogs with BBB. 相似文献