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Effects of carrier structure parameters on diesel particulate filter capture performance based on grey relational analysis

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PARTICULATE SCIENCE AND TECHNOLOGY 2025年第1期43卷 104-119页

作者： Bao, Guangyuan He, Chao Wang, Dongge Wei, Yunsong Li, Xin Southwest Forestry Univ Key Lab Motor Vehicle Environm Protect & Safety Pl Kunming Peoples R China Tsinghua Univ Sch Vehicle & Mobil Natl Key Lab Intelligent Green Vehicles & Transpor Beijing Peoples R China

To reduce the pressure drop of diesel particulate filter (DPF) as well as improve its collection efficiency. A mathematical model of DPF pressure drop and capture efficiency was established. This research systematically investigates the effects of channels per square inch (CPSI), wall thickness, and carrier ratio on DPF performance through grey relational analysis (GRA) and polynomial approximation algorithm (PAA). The findings reveal that DPF exhibits lower pressure drop and higher collection efficiency in the case where the carrier ratio, wall thickness, and CPSI are within the ranges of 1.40 to 1.53, 9.8 to 10.5 mil, and 200 to 300, respectively. Particularly, at a carrier ratio of 1.52 and a wall thickness of 10.38 mil, the pressure drop reaches a minimum value of 4.23 kPa, with a collection efficiency of 90.28%. Meanwhile, at a carrier ratio of 1.52 and a CPSI of 200, the pressure drop reaches a minimum value of 4.17 kPa, with a collection efficiency of 90.21%. The model expressions for pressure drop and collection efficiency derived from the PAA are: y(1) = 51.19 + 3.815x(1) - 8.726x(2) + 3.794x(1)(2) - 1.735x(1)x(2) + 0.524x(2)(2), and y(2) = 0.383 + 0.105x(1) + 0.085x(2) + 0.032x(1)(2) - 0.016x(1)x(2) - 0.0032x(2)(2). The foregoing models exhibit excellent predictive accuracy and goodness of fit for the DPF performance. Under the interactive influence of carrier ratio and wall thickness, the root mean square errors (RMSE) for pressure drop and collection efficiency are 0.0110 and 0.0002, respectively, with corresponding goodness of fit values of 0.9996 and 0.9985. As revealed by the GRA results, wall thickness exerts the most significant impact on DPF performance, presenting a GRG of 0.84 for filtration efficiency and 0.79 for pressure drop. The overall influence on both collection efficiency and pressure drop follows the descending order: wall thickness > carrier ratio > CPSI. This work has important engineering significance for optimizing the DPF capture p

关键词： Diesel particulate filter grey relational analysis polynomial approximation algorithm pressure drop collection efficiency

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approximation of dense-n/2-subgraph and the complement of min-bisection

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JOURNAL OF GLOBAL OPTIMIZATION 2003年第1期25卷 55-73页

作者： Ye, YY Zhang, JW Univ Iowa Henry B Tippie Coll Business Dept Management Sci Iowa City IA 52242 USA

We consider the DENSE- n/2-SUBGRAPH problem, i.e., determine a block of half number nodes from a weighted graph such that the sum of the edge weights, within the subgraph induced by the block, is maximized. We prove that a strengthened semidefinite relaxation with a mixed rounding technique yields a 0.586 approximations of the problem. The previous best-known results for approximating this problem are 0.25 using a simple coin-toss randomization, 0.48 using a semidefinite relaxation, 0.5 using a linear programming relaxation or another semidefinite relaxation. In fact, an un-strengthened SDP relaxation provably yields no more than 0.5 approximation. We also consider the complement of the graph MIN-BISECTION problem, i.e., partitioning the nodes into two blocks of equal cardinality so as to maximize the weights of non-crossing edges. We present a 0.602 approximation of the complement of MIN-BISECTION.

关键词： min-bisection dense-k-subgraph polynomial approximation algorithm semidefinite programming

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On approximation of max-vertex-cover

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EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2002年第2期143卷 342-355页

作者： Han, QM Ye, YY Zhang, HT Zhang, JW Nanjing Normal Univ Grad Sch Management Sci & Engn Nanjing 210093 Peoples R China Univ Iowa Henry B Tippie Coll Business Dept Management Sci Iowa City IA 52242 USA Univ Iowa Dept Comp Sci Iowa City IA 52242 USA Univ Iowa Dept Management Sci Computat Optimizat Lab Iowa City IA 52242 USA

We consider the max-vertex-cover (MVC) problem. i.e., find k vertices from an undirected and edge-weighted graph G = (V, E), where \V\ = n greater than or equal to k, such that the total edge weight covered by the k vertices is maximized. There is a 3/4-approximation algorithm for MVC, based on a linear programming relaxation, We show that the guaranteed ratio can be improved by a simple greedy algorithm for k > (3/4)n, and a simple randomized algorithm for k > (1/2)n. Furthermore, we study a semidefinite programming (SDP) relaxation based approximation algorithms for MVC. We show that, for a range of k, our SDP-based algorithm achieves the best performance guarantee among the four types of algorithms mentioned in this paper. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： max-vertex-cover polynomial approximation algorithm linear programming semidefinite programming

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An improved rounding method and semidefinite programming relaxation for graph partition

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MATHEMATICAL PROGRAMMING 2002年第3期92卷 509-535页

作者： Han, QM Ye, YY Zhang, JW Nanjing Normal Univ Sch Math & Comp Sci Nanjing 210097 Peoples R China Univ Iowa Henry B Tippie Coll Business Dept Management Sci Iowa City IA 52242 USA

Given an undirected graph G = (V, E) with \V\ = n and an integer k between 0 and n, the maximization graph partition (MAX-GP) problem is to determine a subset S C V of k nodes such that an objective function w(S) is maximized. The MAX-GP problem can be formulated as a binary quadratic program and it is NP-hard. Semidefinite programming (SDP) relaxations Of Such quadratic programs have been used to design approximation algorithms with guaranteed performance ratios for various MAX-GP problems. Based on several earlier results, we present an improved rounding method using an SDP relaxation, and establish improved approximation ratios for several MAX-GP problems, including Dense-Subgraph, Max-Cut, Max-Not-Cut, and Max-Vertex-Cover.

关键词： dense-k-subgraph Max-Cut Max-Not-Cut Max-Vertex-Cover polynomial approximation algorithm performance ratio semidefinite programming

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