Maintenance decision problems generally involve multiple criteria which apparently are best addressed using Multi-Criteria Decision Making (MCDM) tools. This paper describes the use of a hybrid MCDM technique in prior...Maintenance decision problems generally involve multiple criteria which apparently are best addressed using Multi-Criteria Decision Making (MCDM) tools. This paper describes the use of a hybrid MCDM technique in prioritizing maintenance strategy for ship systems. The Hybrid MCDM technique combines Delphi method, AHP and TOPSIS methods. While the Delphi method and AHP are applied in screening of decision criteria and decision criteria weights determination respectively, the TOPSIS method is used in the ranking of alternative maintenance strategies. Five alternative maintenance strategies which include corrected maintenance, scheduled overhaul, scheduled replacement, continuous on-condition task and scheduled on-condition task are considered and the optimum maintenance strategy is selected based on twelve critical maintenance decision criteria. To demonstrate the suitability of the approach a case study of sea water pump of the central cooling system of a marine diesel engine is used.展开更多
In the context of food security,drying is a crucial postharvest process for paddy grain because it significantly impacts the quality of both paddy and rice.To conserve energy during the drying process,deep bed dryers ...In the context of food security,drying is a crucial postharvest process for paddy grain because it significantly impacts the quality of both paddy and rice.To conserve energy during the drying process,deep bed dryers are used as convective dryers that use a combination of ambient airflow and heating,thus relying on airflow,temperature,and relative humidity(RH)as the primary drying parameters.Consequently,an aeration system is necessary so that the drying air can penetrate the thick pile of paddy grain and distribute evenly throughout the drying chamber.This analysis aimed to determine the most optimal aeration system by using computational fluid dynamics(CFD)and the AHP-TOPSIS method.The quantitative and visual analysis of the airflow velocity,pressure,temperature,and RH was conducted using CFD on four different dryer aeration systems models,which were then ranked by preference value using the AHP-TOPSIS method.Model 4,with a sloping floor and circular pipe formation,was found to have the most optimal aeration system(preference value of 0.788)for a paddy grain deep bed dryer prototype.展开更多
为科学评估水电站与抽水蓄能联合运行的综合性能,提出一种基于层次分析法(analytic hierarchy process,AHP)与逼近理想解排序法(technique for order preference by similarity to an ideal solution,TOPSIS)相结合的多指标综合评价模...为科学评估水电站与抽水蓄能联合运行的综合性能,提出一种基于层次分析法(analytic hierarchy process,AHP)与逼近理想解排序法(technique for order preference by similarity to an ideal solution,TOPSIS)相结合的多指标综合评价模型。首先,从经济性、技术性、环境效益、水情及政策5个维度出发,构建包含发电效率、调峰能力、碳排放强度、来水量变化等11项指标的综合评价体系。其次,采用AHP确定各指标权重以体现不同维度的差异性影响,并通过TOPSIS计算各运行方案与理想解的贴近度,实现联合运行模式的优劣排序。最后,以某区域水电站与抽水蓄能联合工程为实例进行验证分析。结果表明:相较于传统单一评价方法,AHP-TOPSIS模型能够有效兼顾主客观因素,量化评价结果,其中调峰能力与动态投资回收期对综合性能影响显著;同时,联合运行方案中储能容量配置与调度策略的协同优化可提升系统综合效益15%以上。研究结果为多能互补系统中水电-抽蓄联合运行的方案优选与决策制定提供了理论依据,对推动清洁能源高效利用具有实际意义。展开更多
This study systematically conducted preparation optimization and performance investigations on Co-modified Ce/TiO_(2) catalysts,with a focus on examining how preparation methods and Co loading regulate the catalyst’s...This study systematically conducted preparation optimization and performance investigations on Co-modified Ce/TiO_(2) catalysts,with a focus on examining how preparation methods and Co loading regulate the catalyst’s low-temperature denitrification activity.After identifying optimal preparation parameters via condition screening,multiple characterization techniques-including BET,XRD,XPS,H_(2)-TPR and in situ DRIFTS-were employed to deeply analyze the catalyst’s physicochemical properties and reaction mechanism.Results demonstrated that compared to the impregnation and co-precipitation methods,the Ce-Co_(0.025)/TiO_(2)-SG catalyst(prepared by the sol-gel method with a Co/Ti mass ratio of 0.025)exhibited significantly superior denitrification activity:NO conversion remained stably above 95%in the 225−350℃ temperature range,and it displayed high N_(2) selectivity.Characterization analysis revealed that abundant surface oxygen vacancies,a high proportion of Ce^(3+) species,and prominent acidic sites collectively contributed to enhancing its low-temperature denitrification performance.This work provides reference value for the development of highly efficient low-temperature denitrification catalysts.展开更多
In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
文摘Maintenance decision problems generally involve multiple criteria which apparently are best addressed using Multi-Criteria Decision Making (MCDM) tools. This paper describes the use of a hybrid MCDM technique in prioritizing maintenance strategy for ship systems. The Hybrid MCDM technique combines Delphi method, AHP and TOPSIS methods. While the Delphi method and AHP are applied in screening of decision criteria and decision criteria weights determination respectively, the TOPSIS method is used in the ranking of alternative maintenance strategies. Five alternative maintenance strategies which include corrected maintenance, scheduled overhaul, scheduled replacement, continuous on-condition task and scheduled on-condition task are considered and the optimum maintenance strategy is selected based on twelve critical maintenance decision criteria. To demonstrate the suitability of the approach a case study of sea water pump of the central cooling system of a marine diesel engine is used.
基金funded by Balai Pembiayaan Pendidikan Tinggi,Kemendikbudristek,and Lembaga Pengelola Dana Pendidikan(LPDP)through the Indonesian Education Scholarship(1083/J5.2.3/BPI.06/10/2021)supported by Prof.Samsul Rizal of the Department of Mechanical and Industrial Engineering of Universitas Syiah Kuala in the application of Ansys software,which was funded by the LPDP and managed by Indonesian Science Fund(RISPRO/KI/B1/TKL/5/15448/2020)。
文摘In the context of food security,drying is a crucial postharvest process for paddy grain because it significantly impacts the quality of both paddy and rice.To conserve energy during the drying process,deep bed dryers are used as convective dryers that use a combination of ambient airflow and heating,thus relying on airflow,temperature,and relative humidity(RH)as the primary drying parameters.Consequently,an aeration system is necessary so that the drying air can penetrate the thick pile of paddy grain and distribute evenly throughout the drying chamber.This analysis aimed to determine the most optimal aeration system by using computational fluid dynamics(CFD)and the AHP-TOPSIS method.The quantitative and visual analysis of the airflow velocity,pressure,temperature,and RH was conducted using CFD on four different dryer aeration systems models,which were then ranked by preference value using the AHP-TOPSIS method.Model 4,with a sloping floor and circular pipe formation,was found to have the most optimal aeration system(preference value of 0.788)for a paddy grain deep bed dryer prototype.
文摘为科学评估水电站与抽水蓄能联合运行的综合性能,提出一种基于层次分析法(analytic hierarchy process,AHP)与逼近理想解排序法(technique for order preference by similarity to an ideal solution,TOPSIS)相结合的多指标综合评价模型。首先,从经济性、技术性、环境效益、水情及政策5个维度出发,构建包含发电效率、调峰能力、碳排放强度、来水量变化等11项指标的综合评价体系。其次,采用AHP确定各指标权重以体现不同维度的差异性影响,并通过TOPSIS计算各运行方案与理想解的贴近度,实现联合运行模式的优劣排序。最后,以某区域水电站与抽水蓄能联合工程为实例进行验证分析。结果表明:相较于传统单一评价方法,AHP-TOPSIS模型能够有效兼顾主客观因素,量化评价结果,其中调峰能力与动态投资回收期对综合性能影响显著;同时,联合运行方案中储能容量配置与调度策略的协同优化可提升系统综合效益15%以上。研究结果为多能互补系统中水电-抽蓄联合运行的方案优选与决策制定提供了理论依据,对推动清洁能源高效利用具有实际意义。
基金Supported by the National Key Research and Development Program of China (2023YFB4102903)。
文摘This study systematically conducted preparation optimization and performance investigations on Co-modified Ce/TiO_(2) catalysts,with a focus on examining how preparation methods and Co loading regulate the catalyst’s low-temperature denitrification activity.After identifying optimal preparation parameters via condition screening,multiple characterization techniques-including BET,XRD,XPS,H_(2)-TPR and in situ DRIFTS-were employed to deeply analyze the catalyst’s physicochemical properties and reaction mechanism.Results demonstrated that compared to the impregnation and co-precipitation methods,the Ce-Co_(0.025)/TiO_(2)-SG catalyst(prepared by the sol-gel method with a Co/Ti mass ratio of 0.025)exhibited significantly superior denitrification activity:NO conversion remained stably above 95%in the 225−350℃ temperature range,and it displayed high N_(2) selectivity.Characterization analysis revealed that abundant surface oxygen vacancies,a high proportion of Ce^(3+) species,and prominent acidic sites collectively contributed to enhancing its low-temperature denitrification performance.This work provides reference value for the development of highly efficient low-temperature denitrification catalysts.
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
