To improve the inconsistency in the analytic hierarchy process(AHP), a new method based on marginal optimization theory is proposed. During the improving process, this paper regards the reduction of consistency ratio(...To improve the inconsistency in the analytic hierarchy process(AHP), a new method based on marginal optimization theory is proposed. During the improving process, this paper regards the reduction of consistency ratio(CR) as benefit, and the maximum modification compared to the original pairwise comparison matrix(PCM) as cost, then the improvement of consistency is transformed to a benefit/cost analysis problem. According to the maximal marginal effect principle, the elements of PCM are modified by a fixed increment(or decrement) step by step till the consistency ratio becomes acceptable, which can ensure minimum adjustment to the original PCM so that the decision makers’ judgment is preserved as much as possible. The correctness of the proposed method is proved mathematically by theorem. Firstly, the marginal benefit/cost ratio is calculated for each single element of the PCM when it has been modified by a fixed increment(or decrement).Then, modification to the element with the maximum marginal benefit/cost ratio is accepted. Next, the marginal benefit/cost ratio is calculated again upon the revised matrix, and followed by choosing the modification to the element with the maximum marginal benefit/cost ratio. The process of calculating marginal effect and choosing the best modified element is repeated for each revised matrix till acceptable consistency is reached, i.e., CR<0.1. Finally,illustrative examples show the proposed method is more effective and better in preserving the original comparison information than existing methods.展开更多
he Al_2O_3 particle reinforced aluminum matrix composite was prepared by using a new pressureless infiltration process. The microstructure of (Al_2O_3)p/Al was analyzed. The tension and the thermal conductivity of the...he Al_2O_3 particle reinforced aluminum matrix composite was prepared by using a new pressureless infiltration process. The microstructure of (Al_2O_3)p/Al was analyzed. The tension and the thermal conductivity of the composite were studied as well.展开更多
The hot deformation characteristics of TiC particles reinforced titanium matrix composite were studied in the temperature range from 900 ℃ to 1 150 ℃ and in the strain rate range of 10-3-10 s-1 by compression tests ...The hot deformation characteristics of TiC particles reinforced titanium matrix composite were studied in the temperature range from 900 ℃ to 1 150 ℃ and in the strain rate range of 10-3-10 s-1 by compression tests with Gleeble1500 simulator system. The flow behavior was described by the hyperbolic sine constitutive equation,and an average activation energy of 436.72 kJ/mol was calculated. The processing maps were calculated and analyzed according to the dynamic materials model. The maps show domains in some combinations of temperatures and strain rates and these domains are correlated with specific microstructural processes occurring during hot deformation by metallographic investigations and kinetic analysis. At the low strain rate domain occurs in the temperature range of 900-960 ℃ and strain rate range of 0.001-0.03 s-1 superplasticity and dynamic recrystallization were observed. At a high strain rate domain occurs in the temperature range of 980-1 120 ℃ and strain rate range of 0.1-10 s-1 the β phase undergoes dynamic recrystallization. Also,at a strain rate range of 0.1-10 s-1 and the temperature range of 900-930 ℃,the material exhibits flow localization.展开更多
A quenching and partitioning(Q&P) process was applied to vanadium carbide particle(VCp)-reinforced Fe-matrix composites(VC-Fe-MCs) to obtain a multiphase microstructure comprising VC, V8 C7, M3 C, α-Fe, and γ-Fe...A quenching and partitioning(Q&P) process was applied to vanadium carbide particle(VCp)-reinforced Fe-matrix composites(VC-Fe-MCs) to obtain a multiphase microstructure comprising VC, V8 C7, M3 C, α-Fe, and γ-Fe. The effects of the austenitizing temperature and the quenching temperature on the microstructure, mechanical properties, and wear resistance of the VC-Fe-MCs were studied. The results show that the size of the carbide became coarse and that the shape of some particles began to transform from diffused graininess into a chrysanthemum-shaped structure with increasing austenitizing temperature. The microhardness decreased with increasing austenitizing temperature but substantially increased after wear testing compared with the microhardness before wear testing; the microhardness values improved by 20.0% ± 2.5%. Retained austenite enhanced the impact toughness and promoted the transformation-induced plasticity(TRIP) effect to improve wear resistance under certain load conditions.展开更多
In this paper the Expendable Pattern Casting with dry sand Vacuum(EPC-V) process is used to manufacture iron matrix composites with tungsten carbide particle.Microstructures of the composites layers were analyzed.The ...In this paper the Expendable Pattern Casting with dry sand Vacuum(EPC-V) process is used to manufacture iron matrix composites with tungsten carbide particle.Microstructures of the composites layers were analyzed.The abrasive wear resistance of the composites layers were tested and compared with that of high chromium cast iron.The results show that the iron matrix composites with tungsten carbide particle have high hardness.The abrasive wear resistance of composites with tungsten carbide particle is higher than that of high chromium cast iron.The properties of the matrix materials have been improved remarkably.展开更多
基金supported by the National Natural Science Foundation of China(6160150161502521)
文摘To improve the inconsistency in the analytic hierarchy process(AHP), a new method based on marginal optimization theory is proposed. During the improving process, this paper regards the reduction of consistency ratio(CR) as benefit, and the maximum modification compared to the original pairwise comparison matrix(PCM) as cost, then the improvement of consistency is transformed to a benefit/cost analysis problem. According to the maximal marginal effect principle, the elements of PCM are modified by a fixed increment(or decrement) step by step till the consistency ratio becomes acceptable, which can ensure minimum adjustment to the original PCM so that the decision makers’ judgment is preserved as much as possible. The correctness of the proposed method is proved mathematically by theorem. Firstly, the marginal benefit/cost ratio is calculated for each single element of the PCM when it has been modified by a fixed increment(or decrement).Then, modification to the element with the maximum marginal benefit/cost ratio is accepted. Next, the marginal benefit/cost ratio is calculated again upon the revised matrix, and followed by choosing the modification to the element with the maximum marginal benefit/cost ratio. The process of calculating marginal effect and choosing the best modified element is repeated for each revised matrix till acceptable consistency is reached, i.e., CR<0.1. Finally,illustrative examples show the proposed method is more effective and better in preserving the original comparison information than existing methods.
文摘he Al_2O_3 particle reinforced aluminum matrix composite was prepared by using a new pressureless infiltration process. The microstructure of (Al_2O_3)p/Al was analyzed. The tension and the thermal conductivity of the composite were studied as well.
基金Projects(50434030) supported by the National Natural Science Foundation of China
文摘The hot deformation characteristics of TiC particles reinforced titanium matrix composite were studied in the temperature range from 900 ℃ to 1 150 ℃ and in the strain rate range of 10-3-10 s-1 by compression tests with Gleeble1500 simulator system. The flow behavior was described by the hyperbolic sine constitutive equation,and an average activation energy of 436.72 kJ/mol was calculated. The processing maps were calculated and analyzed according to the dynamic materials model. The maps show domains in some combinations of temperatures and strain rates and these domains are correlated with specific microstructural processes occurring during hot deformation by metallographic investigations and kinetic analysis. At the low strain rate domain occurs in the temperature range of 900-960 ℃ and strain rate range of 0.001-0.03 s-1 superplasticity and dynamic recrystallization were observed. At a high strain rate domain occurs in the temperature range of 980-1 120 ℃ and strain rate range of 0.1-10 s-1 the β phase undergoes dynamic recrystallization. Also,at a strain rate range of 0.1-10 s-1 and the temperature range of 900-930 ℃,the material exhibits flow localization.
基金financially supported by the National Natural Science Foundation of China(Nos.51475480 and U1637601)the Research Funding from the State Key Laboratory of High-Performance Complex Manufacturing(No.ZZYJKT2017-01)+1 种基金Innovation Platform and Talent Plan of Hunan Province(No.2016RS2015)the Project of Innovation Driven Plan in Central South University(No.2015CX002)
文摘A quenching and partitioning(Q&P) process was applied to vanadium carbide particle(VCp)-reinforced Fe-matrix composites(VC-Fe-MCs) to obtain a multiphase microstructure comprising VC, V8 C7, M3 C, α-Fe, and γ-Fe. The effects of the austenitizing temperature and the quenching temperature on the microstructure, mechanical properties, and wear resistance of the VC-Fe-MCs were studied. The results show that the size of the carbide became coarse and that the shape of some particles began to transform from diffused graininess into a chrysanthemum-shaped structure with increasing austenitizing temperature. The microhardness decreased with increasing austenitizing temperature but substantially increased after wear testing compared with the microhardness before wear testing; the microhardness values improved by 20.0% ± 2.5%. Retained austenite enhanced the impact toughness and promoted the transformation-induced plasticity(TRIP) effect to improve wear resistance under certain load conditions.
文摘In this paper the Expendable Pattern Casting with dry sand Vacuum(EPC-V) process is used to manufacture iron matrix composites with tungsten carbide particle.Microstructures of the composites layers were analyzed.The abrasive wear resistance of the composites layers were tested and compared with that of high chromium cast iron.The results show that the iron matrix composites with tungsten carbide particle have high hardness.The abrasive wear resistance of composites with tungsten carbide particle is higher than that of high chromium cast iron.The properties of the matrix materials have been improved remarkably.
