脱碳闪蒸气回收方案比较

对碳酸丙烯酯脱碳闪蒸气的３种回收方案进行了比较。通过计算分析,尽管闪蒸气先脱碳再压缩的投资费用较大,但操作费用低,是理想的脱碳闪蒸气回收方案。     

DCS通信故障探析与对策

对姨江石化总厂化肥厂合成氨装置和尿素装置ＤＣＳ系统３闪通信故障进行说明和分析,并提出了系统发生改造方案。     

双斜楔成形模设计

着重论述了异型钢管端头成形方案的分析和对比 ,阐述了双斜楔夹紧机构的设计及双斜楔成形模的设计依据、要点     

美国无损检测学会的雇主认证程序和中心认证程序

介绍美国无损检测学会制订的几种主要的无损检测人员资格鉴定和认证程序,着重分析雇主认证体系和中心认证体系的特点。     

委内瑞拉原油加工方案探讨

由于常规石油资源的可利用量日益减少,在全世界资源中数量相当可观的重质原油将成为21世纪的重要能源。委内瑞拉重质原油由于其粘度大,胶质、沥青质含量高,重金属含量高,使其在输送及加工过程中都存在着与常规原油不同的技术问题。本文介绍了委内瑞拉原油的性质以及加工方案的探讨。     

抛物型方程的一个六阶精度的差分格式及格式稳定性的—种新的证明方法

用待定系数法构违了六阶差分格式,比已有文献的四阶差分格式提高了精度。格式稳定性的证明方法也是新的。     

尿素合成塔换衬技术方案探讨

通过对尿素合成塔换衬中的简体切割位置、新衬里筒节设置、碳钢简体蚀坑修理、筒节焊接、热处理及检验等相关技术方案进行对比分析、评定,选择出了最佳施工方案,在尿素合成塔整体换衬施工中获得成功。     

Comparison of Two-Level Preconditioners Derived from Deflation,Domain Decomposition and Multigrid Methods

For various applications, it is well-known that a multi-level, in particular two-level, preconditioned CG (PCG) method is an efficient method for solving large and sparse linear systems with a coefficient matrix that is symmetric positive definite. The corresponding two-level preconditioner combines traditional and projection-type preconditioners to get rid of the effect of both small and large eigenvalues of the coefficient matrix. In the literature, various two-level PCG methods are known, coming from the fields of deflation, domain decomposition and multigrid. Even though these two-level methods differ a lot in their specific components, it can be shown that from an abstract point of view they are closely related to each other. We investigate their equivalences, robustness, spectral and convergence properties, by accounting for their implementation, the effect of roundoff errors and their sensitivity to inexact coarse solves, severe termination criteria and perturbed starting vectors.     

船舶余热动力回收系统的优化及热线图的比较

本文建立了船舶余热动力回收系统热力学参数优化的计算模型,讨论了系统热线图的评价指标.通过对一实际船舶余热动力回收系统的检验计算,证明了该优化计算模型的正确性.在此基础上,从系统的经济学和热力学两方面出发,对常用几种典型的余热动力回收系统热线图进行了研究,指出了各自的应用范围和优缺点.     

Non-Linear Filtering and Limiting in High Order Methods for Ideal and Non-Ideal MHD

The adaptive nonlinear filtering and limiting in spatially high order schemes (Yee et al. J. Comput. Phys. 150, 199–238, (1999), Sjögreen and Yee, J. Scient. Comput. 20, 211–255, (2004)) for the compressible Euler and Navier–Stokes equations have been recently extended to the ideal and non-ideal magnetohydrodynamics (MHD) equations, (Sjögreen and Yee, (2003), Proceedings of the 16th AIAA/CFD conference, June 23–26, Orlando F1; Yee and Sjögreen (2003), Proceedings of the International Conference on High Performance Scientific Computing, March, 10–14, Honai, Vietnam; Yee and Sjögreen (2003), RIACS Technical Report TR03. 10, July, NASA Ames Research Center; Yee and Sjögreen (2004), Proceedings of the ICCF03, July 12–16, Toronto, Canada). The numerical dissipation control in these adaptive filter schemes consists of automatic detection of different flow features as distinct sensors to signal the appropriate type and amount of numerical dissipation/filter where needed and leave the rest of the region free from numerical dissipation contamination. The numerical dissipation considered consists of high order linear dissipation for the suppression of high frequency oscillation and the nonlinear dissipative portion of high-resolution shock-capturing methods for discontinuity capturing. The applicable nonlinear dissipative portion of high-resolution shock-capturing methods is very general. The objective of this paper is to investigate the performance of three commonly used types of discontinuity capturing nonlinear numerical dissipation for both the ideal and non-ideal MHD.