To explore the effect of removing different impurities to hydrogen networks, an MINLP model is proposed with all matching possibilities and the trade-off between operation cost and capital cost is considered. Furtherm...To explore the effect of removing different impurities to hydrogen networks, an MINLP model is proposed with all matching possibilities and the trade-off between operation cost and capital cost is considered. Furthermore,the impurity remover, hydrogen distribution, compressor and pipe setting are included in the model. Based on this model, the impurity and source(s) that are in higher priority for impurity removal, the optimal targeted concentration, and the hydrogen network with the minimum annual cost can be identified. The efficiency of the proposed model is verified by a case study.展开更多
Multiplicative noise removal problems have attracted much attention in recent years.Unlike additive noise,multiplicative noise destroys almost all information of the original image,especially for texture images.Motiva...Multiplicative noise removal problems have attracted much attention in recent years.Unlike additive noise,multiplicative noise destroys almost all information of the original image,especially for texture images.Motivated by the TV-Stokes model,we propose a new two-step variational model to denoise the texture images corrupted by multiplicative noise with a good geometry explanation in this paper.In the first step,we convert the multiplicative denoising problem into an additive one by the logarithm transform and propagate the isophote directions in the tangential field smoothing.Once the isophote directions are constructed,an image is restored to fit the constructed directions in the second step.The existence and uniqueness of the solution to the variational problems are proved.In these two steps,we use the gradient descent method and construct finite difference schemes to solve the problems.Especially,the augmented Lagrangian method and the fast Fourier transform are adopted to accelerate the calculation.Experimental results show that the proposed model can remove the multiplicative noise efficiently and protect the texture well.展开更多
Mercury emission has become a great environmental concern because of its high toxicity,bioaccumulation,and persistence.Adsorption is an effective method to remove Hg^(0)from coal-fired flue gas,with adsorbents playing...Mercury emission has become a great environmental concern because of its high toxicity,bioaccumulation,and persistence.Adsorption is an effective method to remove Hg^(0)from coal-fired flue gas,with adsorbents playing a dominant role.Extensive investigations have been conducted on the use of CuO-based materials for Hg^(0)removal,and some fruitful results have been obtained.In this review,we summarize advances in the application of CuO-based materials for Hg^(0)capture.Firstly,the fundamentals of CuO,including its crystal information and synthesis methods,are introduced.Then,the Hg^(0)removal capability of some typical CuO-based adsorbents is discussed.Considering that coal-fired flue gas also contains a certain amount of NO,SO_(2),H_(2)O,NH_(3),and HCl,the impacts of these species on adsorbent Hg^(0)removal efficiency are summarized next.By generalizing the mechanisms dominating the Hg^(0)removal process,the rate-determining step and the key intermediates can be discovered.Apart from Hg^(0),some other air pollutants,such as CO,NOx,and volatile organic compounds(VOCs),account for a certain portion of flue gas.In view of their similar abatement mechanisms,simultaneous removal of Hg^(0)and other air pollutants has become a hot topic in the environmental field.Considering the Hg^(0)re-emission phenomena in wet flue gas desulfurization(WFGD),mercury capture performance under different conditions in this device is discussed.Finally,we conclude that new adsorbents suitable for long-term operation in coal-fired flue gas should be developed to realize the effective reduction of mercury emissions.展开更多
Nitrous oxide（N_2O） is a potent greenhouse gas that can be emitted during biological nitrogen removal. N_2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600 m L/min sequenc...Nitrous oxide（N_2O） is a potent greenhouse gas that can be emitted during biological nitrogen removal. N_2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600 m L/min sequencing batch reactor（SBRL） and 1200 m L/min（SBRH）.The nitrogen removal percentage was 89% in SBRLand 71% in SBRH, respectively. N_2O emission mainly occurred during the aerobic phase, and the N_2O emission factor was 10.1%in SBRLand 2.3% in SBRH, respectively. In all batch experiments, the N_2O emission potential was high in SBRLcompared with SBRH. In SBRL, with increasing aeration rates, the N_2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification（SND）. By contrast, in SBRHthe N_2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N_2O emission during biological nitrogen removal.展开更多
With the increase of space debris,space debris removal has gradually become a major issue to address by worldwide space agencies.Multiple debris removal missions,in which multiple debris objects are removed in a singl...With the increase of space debris,space debris removal has gradually become a major issue to address by worldwide space agencies.Multiple debris removal missions,in which multiple debris objects are removed in a single mission,are an economical approach to purify the space environment.Such missions can be considered typical time-dependent traveling salesman problems(TDTSPs).In this study,an intelligent global optimization algorithm called Timeline Club Optimization(TCO)is proposed to solve multiple debris removal missions of the TDTSP model.TCO adopts the traditional ant colony optimization(ACO)framework and replaces the pheromone matrix of the ACO with a new structure called the Timeline Club.The Timeline Club records which debris object to be removed next at a certain moment from elitist solutions and decides the probability criterion to generate debris sequences in new solutions.Two hypothetical scenarios,the Iridium-33 mission and the GTOC9 mission,are considered in this study.Simulation results show that TCO offers better performance than those of beam search,ant colony optimization,and the genetic algorithm in multiple debris removal missions of the TDTSP model.展开更多
Recently,attenuation of surface-related multiples is implemented by a large-scale sparsity-promoting inversion where the primaries are iteratively estimated without a subtraction process,which is called estimation of ...Recently,attenuation of surface-related multiples is implemented by a large-scale sparsity-promoting inversion where the primaries are iteratively estimated without a subtraction process,which is called estimation of primaries by sparse inversion(EPSI).By inverting for surface-free impulse responses,EPSI simultaneously updates the primaries and multiples,both of which contribute to explaining the input data,and therefore promote the global convergence gradually.However,one of the major concerns of EPSI may lie in its high computational cost.In this paper,based on the same gradient-descent framework with EPSI,we develop a computationally cost-effective primary estimation approach in which a newly defined parameterization of primary-multiple model is adopted and an efficiently defined analytical step-length is developed.The developed approach can yield a better primary estimation at less computational cost as compared to EPSI,which is verified by two synthetic datasets in numerical examples.Moreover,we apply this approach to a shallow-water field dataset and achieve a desirable performance.展开更多
基金Supported by the National Natural Science Foundation of China(21276205)
文摘To explore the effect of removing different impurities to hydrogen networks, an MINLP model is proposed with all matching possibilities and the trade-off between operation cost and capital cost is considered. Furthermore,the impurity remover, hydrogen distribution, compressor and pipe setting are included in the model. Based on this model, the impurity and source(s) that are in higher priority for impurity removal, the optimal targeted concentration, and the hydrogen network with the minimum annual cost can be identified. The efficiency of the proposed model is verified by a case study.
文摘Multiplicative noise removal problems have attracted much attention in recent years.Unlike additive noise,multiplicative noise destroys almost all information of the original image,especially for texture images.Motivated by the TV-Stokes model,we propose a new two-step variational model to denoise the texture images corrupted by multiplicative noise with a good geometry explanation in this paper.In the first step,we convert the multiplicative denoising problem into an additive one by the logarithm transform and propagate the isophote directions in the tangential field smoothing.Once the isophote directions are constructed,an image is restored to fit the constructed directions in the second step.The existence and uniqueness of the solution to the variational problems are proved.In these two steps,we use the gradient descent method and construct finite difference schemes to solve the problems.Especially,the augmented Lagrangian method and the fast Fourier transform are adopted to accelerate the calculation.Experimental results show that the proposed model can remove the multiplicative noise efficiently and protect the texture well.
基金This work is supported by the Scientific Research Foundation of China Jiliang Universitythe Zhejiang Provincial Natural Science Foundation of China(Nos.LQ22E060003 and LY22E040001).
文摘Mercury emission has become a great environmental concern because of its high toxicity,bioaccumulation,and persistence.Adsorption is an effective method to remove Hg^(0)from coal-fired flue gas,with adsorbents playing a dominant role.Extensive investigations have been conducted on the use of CuO-based materials for Hg^(0)removal,and some fruitful results have been obtained.In this review,we summarize advances in the application of CuO-based materials for Hg^(0)capture.Firstly,the fundamentals of CuO,including its crystal information and synthesis methods,are introduced.Then,the Hg^(0)removal capability of some typical CuO-based adsorbents is discussed.Considering that coal-fired flue gas also contains a certain amount of NO,SO_(2),H_(2)O,NH_(3),and HCl,the impacts of these species on adsorbent Hg^(0)removal efficiency are summarized next.By generalizing the mechanisms dominating the Hg^(0)removal process,the rate-determining step and the key intermediates can be discovered.Apart from Hg^(0),some other air pollutants,such as CO,NOx,and volatile organic compounds(VOCs),account for a certain portion of flue gas.In view of their similar abatement mechanisms,simultaneous removal of Hg^(0)and other air pollutants has become a hot topic in the environmental field.Considering the Hg^(0)re-emission phenomena in wet flue gas desulfurization(WFGD),mercury capture performance under different conditions in this device is discussed.Finally,we conclude that new adsorbents suitable for long-term operation in coal-fired flue gas should be developed to realize the effective reduction of mercury emissions.
基金supported by the Shenzhen Overseas High-Level Talents Innovation Funds Peacock Plan Project (No. KQCX20120814155347053)the National Natural Science Foundation of China (No. 51108242)
文摘Nitrous oxide（N_2O） is a potent greenhouse gas that can be emitted during biological nitrogen removal. N_2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600 m L/min sequencing batch reactor（SBRL） and 1200 m L/min（SBRH）.The nitrogen removal percentage was 89% in SBRLand 71% in SBRH, respectively. N_2O emission mainly occurred during the aerobic phase, and the N_2O emission factor was 10.1%in SBRLand 2.3% in SBRH, respectively. In all batch experiments, the N_2O emission potential was high in SBRLcompared with SBRH. In SBRL, with increasing aeration rates, the N_2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification（SND）. By contrast, in SBRHthe N_2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N_2O emission during biological nitrogen removal.
基金This research was supported by the National Key R&D Program of China(No.2019YFA0706500).
文摘With the increase of space debris,space debris removal has gradually become a major issue to address by worldwide space agencies.Multiple debris removal missions,in which multiple debris objects are removed in a single mission,are an economical approach to purify the space environment.Such missions can be considered typical time-dependent traveling salesman problems(TDTSPs).In this study,an intelligent global optimization algorithm called Timeline Club Optimization(TCO)is proposed to solve multiple debris removal missions of the TDTSP model.TCO adopts the traditional ant colony optimization(ACO)framework and replaces the pheromone matrix of the ACO with a new structure called the Timeline Club.The Timeline Club records which debris object to be removed next at a certain moment from elitist solutions and decides the probability criterion to generate debris sequences in new solutions.Two hypothetical scenarios,the Iridium-33 mission and the GTOC9 mission,are considered in this study.Simulation results show that TCO offers better performance than those of beam search,ant colony optimization,and the genetic algorithm in multiple debris removal missions of the TDTSP model.
基金support to our research group.The research is supported by National Natural Science Foundation of China(Grants 41730425,41430321)National Oil and Gas Major Project of China(Grant 2017ZX05008-007).
文摘Recently,attenuation of surface-related multiples is implemented by a large-scale sparsity-promoting inversion where the primaries are iteratively estimated without a subtraction process,which is called estimation of primaries by sparse inversion(EPSI).By inverting for surface-free impulse responses,EPSI simultaneously updates the primaries and multiples,both of which contribute to explaining the input data,and therefore promote the global convergence gradually.However,one of the major concerns of EPSI may lie in its high computational cost.In this paper,based on the same gradient-descent framework with EPSI,we develop a computationally cost-effective primary estimation approach in which a newly defined parameterization of primary-multiple model is adopted and an efficiently defined analytical step-length is developed.The developed approach can yield a better primary estimation at less computational cost as compared to EPSI,which is verified by two synthetic datasets in numerical examples.Moreover,we apply this approach to a shallow-water field dataset and achieve a desirable performance.
