The violation of monotonicity on reliability measures(RMs)usually makes the mathematical programming algorithms less efficient in solving the reliability-based user equilibrium(RUE)problem.The swapping algorithms prov...The violation of monotonicity on reliability measures(RMs)usually makes the mathematical programming algorithms less efficient in solving the reliability-based user equilibrium(RUE)problem.The swapping algorithms provide a simple and convenient alternative to search traffic equilibrium since they are derivative-free and require weaker monotonicity.However,the existing swapping algorithms are usually based on linear swapping processes which cannot naturally avoid overswapping,and the step-size parameter update methods do not take the swapping feature into account.In this paper,we suggest a self-regulating pairwise swapping algorithm(SRPSA)to search RUE.SRPSA comprises an RM-based pairwise swapping process(RMPSP),a parameter self-diminishing operator and a termination criterion.SRPSA does not need to check the feasibility of either solutions or step-size parameter.It is suggested from the numerical analyses that SRPSA is effective and can swap to the quasi-RUE very fast.Therefore,SRPSA offers a good approach to generate initial points for those superior local search algorithms.展开更多
Rapid development of portable or wearable devices, which is inspired by requirements of instant messaging,health monitoring and handling official business, urgently demands more tiny, flexible and light power sources....Rapid development of portable or wearable devices, which is inspired by requirements of instant messaging,health monitoring and handling official business, urgently demands more tiny, flexible and light power sources. Fibershaped batteries explored in recent years become a prospective candidate to satisfy these demands. With 1D architecture,the fiber-shaped batteries could be adapted to various deformations and integrated into soft textile and other devices.Numerous researches have been reported and achieved huge promotion. To give an overview of fiber-shaped batteries,we summarized the development of fiber-shaped batteries in this review, and discussed the structure and materials in fiber-shaped batteries. The flexibility of batteries with the potential application of the batteries was also exhibited and showed the future perspective. Finally, challenges in this field were discussed, hoping to reveal research direction towards further development of fiber-shaped batteries.展开更多
CO_(2),as a greenhouse gas,has excessive emissions that lead to many environmental problems and is a rich and cheap C1 resource.Effective utilization and transformation of CO_(2)has become an important means of achiev...CO_(2),as a greenhouse gas,has excessive emissions that lead to many environmental problems and is a rich and cheap C1 resource.Effective utilization and transformation of CO_(2)has become an important means of achieving carbon neutrality.Oxazolidinones are important intermediates in pharmaceutical chemistry that can be synthesized by carboxylation cyclization of CO_(2)with propargyl amines or cycloaddition of CO_(2)with aziridines.Owing to CO_(2)’s high stability,these reactions typically require harsh conditions,such as high temperatures or pressures.It is desirable,but challenging,to find a catalyst that can catalyze these two types of reactions under relatively mild conditions.Metal-organic frameworks(MOFs)are an emerging class of heterogeneous catalysts that with great potential in the catalytic conversion of CO_(2)to value-added products because of their attractive features,such as abundant metal active sites,inherent porosity,and easy functionalities.Herein,a unique three-dimensional(3D)MOF,{(CH_(3)NH_(2)CH_(3))_(2)[Co_(3)(BCP)_(2)]·6H_(2)O·4DMF}n(1)(H_(4)BCP:5‐(2,6‐bis(4‐carboxyphenyl)pyridin‐4‐yl)isophthalic acid;DMF:N,N'‐dimethylformamide),was synthesized using carboxylic acid ligands and cobalt salts via a solvothermal method.According to structural analysis,[Co_(3)]clusters as secondary building units(SBU)are bridged by BCP4−ligands,forming an anion framework with flu topology,and dimethylamine cations act as counter ions in the pores.The framework has rectangular channels of approximately 0.4 nm×0.9 nm along the a-axis direction,exhibiting its porous property.Infrared spectroscopy(IR)and X-ray photoelectron spectroscopy(XPS)characterizations proved the coordination interaction between the carboxyl groups in the ligands and the metal ions.The powder X-Ray diffraction(PXRD)test further confirmed the phase purity of the synthesized samples.PXRD and thermogravimetry(TG)analyses indicated that 1 possessed good solvent and thermal stabilities.The catalytic experiments revealed that 1 could effectively catalyze CO_(2)with aziridines or propargyl amines to prepare oxazolidinones.In the cycloaddition of CO_(2)with aziridines,1 can facilitate the reaction under relatively mild conditions compared to other reported MOF-based catalysts.It shows excellent universality for substrates with various substitutions on the N atom or benzene ring.Investigation of the mechanism indicated that the coordination interaction of cobalt metal sites with the nitrogen atoms of aziridines can activate the substrates.For the carboxylative cyclization of CO_(2)with propargylic amines,this catalyst also has a broad substrate scope.Control experiments and nuclear magnetic resonance(NMR)tests suggest that Lewis acid metal sites are responsible for the high catalytic efficiency achieved by activating the alkyne groups.Moreover,1 showed good reusability in both reactions.Compound 1 represents a new catalyst that enables“two birds with one stone”in the catalytic synthesis of oxazolidinones using CO_(2).展开更多
The influence of crystallographic orientation on the void growth in FCC crystals was numerically simulated with 3D crystal plasticity finite element by using a 3D unit cell including a spherical void, and the rate-dep...The influence of crystallographic orientation on the void growth in FCC crystals was numerically simulated with 3D crystal plasticity finite element by using a 3D unit cell including a spherical void, and the rate-dependent crystal plasticity theory was implemented as a user material subroutine. The results of the simulations show that crystallographic orientation has significant influence on the growth behavior of the void. Different active slip systems of the regions around the void cause the discontinuity in lattice rotation around the void, and the corner-like region is formed. In the case of the void located at grain boundary, large heterogeneous deformation occurs between the two grains, and the equivalent plastic deformation along grain boundary near the void in the case of θ=45^o （θ is the angle between grain boundary direction and X-axis） is larger than the others. Large difference of orientation factor of the two grains leads to large equivalent plastic deformation along grain boundary, and the unit cell is more likely to fail by intergranular fracture.展开更多
Because the signals of global positioning system （GPS） satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. I...Because the signals of global positioning system （GPS） satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. In this case, the receiver autonomous integrity monitoring （RAIM） method earmot exclude faulty satellite. In order to improve the performance of RAIM method and obtain the reliable positioning results with five satellites, the series of receiver clock bias （RCB） is regarded as one useful satellite and used to aid RAIM method. From the point of nonlinear series, a grey-Markov model for predicting the RCB series based on grey theory and Markov chain is presented. And then the model is used for aiding RAIM method in order to exclude faulty satellite. Experimental results demonstrate that the prediction model is fit for predicting the RCB series, and with the clock-based RAIM method the faulty satellite can be correctly excluded and the positioning precision of GPS receiver can be improved for the case where there are only five useful satellites.展开更多
Advanced traveler information systems （ATIS） can not only improve drivers＇ accessibility to the more accurate route travel time information, but also can improve drivers＇ adaptability to the stochastic network cap...Advanced traveler information systems （ATIS） can not only improve drivers＇ accessibility to the more accurate route travel time information, but also can improve drivers＇ adaptability to the stochastic network capacity degradations. In this paper, a mixed stochastic user equilibrium model was proposed to describe the interactive route choice behaviors between ATIS equipped and unequipped drivers on a degradable transport network. In the proposed model the information accessibility of equipped drivers was reflected by lower degree of uncertainty in their stochastic equilibrium flow distributions, and their behavioral adaptability was captured by multiple equilibrium behaviors over the stochastic network state set. The mixed equilibrium model was formulated as a fixed point problem defined in the mixed route flows, and its solution was achieved by executing an iterative algorithm. Numerical experiments were provided to verify the properties of the mixed network equilibrium model and the efficiency of the iterative algorithm.展开更多
Due to the influence of joint fissure, mining intensity, designed slope angle, underground water and rainfall, the failure process of mine slope project is extremely complicated. The current safety factor calculation ...Due to the influence of joint fissure, mining intensity, designed slope angle, underground water and rainfall, the failure process of mine slope project is extremely complicated. The current safety factor calculation method has certain limitations, and it would be difficult to obtain the reliability index when the performance function of reliability analysis is implicit or has high order terms. Therefore, with the help of the logistic equation of chaos theory, a new algorithm of mine slope reliability based on limiting state hyper-plane is proposed. It is shown that by using this new reliability algorithm the calculation of partial derivative of performance function is avoided, and it has the advantages of being simple and easy to program. The new algorithm is suitable for calculating the reliability index of complex performance function containing high order terms. Furthermore, the limiting state hyper-plane models of both simplified Bishop's and Janbu's method adaptive to slope project are obtained, and have achieved satisfactory effect in the study of mine slope stability in Dexing copper open pit.展开更多
Chloride-induced corrosion of the reinforcement is considered as one of the major mechanisms resulting in the reduction of structural resistance of reinforced concrete structural elements located in marine and other a...Chloride-induced corrosion of the reinforcement is considered as one of the major mechanisms resulting in the reduction of structural resistance of reinforced concrete structural elements located in marine and other aggressive environments. A study of reinforced concrete structures located at the Fangcheng dock in the Beibu Gulf port, China, was present. The result from field survey indicates that the concrete cover depth and chloride diffusion coefficient fit best normal distribution and lognormal distribution, respectively. The service life of structure is about 55 a, while initiation time is 45 a. Sensitivity analysis indicates that the most influential factor of the structure service life prediction is concrete cover, followed by diffusion coefficient, diffusion decay index, critical chloride concentration, surface chloride concentration, current density and localized pitting corrosion. Finally, the effects of diffusion decay index and critical chloride concentration on structure service life prediction are discussed.展开更多
To improve the energy utilization efficiency of internal combustion （IC） engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exer...To improve the energy utilization efficiency of internal combustion （IC） engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exergy balance model was built. The working processes of gasoline engine were simulated by using the GT-power. In this way, the required parameters were calculated and then gasoline engine exergy balance was obtained by programming on computer. On this basis, the influences of various parameters on exergy balance were analyzed. Results show that, the proportions of various forms of exergy in gasoline engine from high to low are irreversible loss, effective work, exhaust gas exergy and heat transfer exergy. Effective exergy proportion fluctuates with cylinder volumetric efficiency at full load, while it always increases with break mean effective pressure （BMEP） at part load. Exhaust gas exergy proportion is more sensitive to speed, and it increases with speed increasing except at the highest speed. The lower proportion of heat transfer exergy appears at high speed and high load. Irreversible loss is mainly influenced by load. At part load, higher BMEP results in lower proportion of irreversible loss; at full load, the proportion of irreversible loss changes little except at the highest speed.展开更多
In order to apply overbooking idea in Chinese railway freight industry to improve revenue, a Markov decision process(dynamic programming) model for railway freight reservation was formulated and the overbooking limit ...In order to apply overbooking idea in Chinese railway freight industry to improve revenue, a Markov decision process(dynamic programming) model for railway freight reservation was formulated and the overbooking limit level was proposed as a control policy. However, computing the dynamic programming treatment needs six nested loops and this will be burdensome for real-world problems. To break through the calculation limit, the properties of value function were analyzed and the overbooking protection level was proposed to reduce the calculating quantity. The simulation experiments show that the overbooking protection level for the lower-fare class is higher than that for the higher-fare class, so the overbooking strategy is nested by fare class. Besides, by analyzing the influence on the overbooking strategy of freight arrival probability and cancellation probability, the proposed approach is efficient and also has a good application prospect in reality. Also, compared with the existing reservation(FCFS), the overbooking strategy performs better in the fields of vacancy reduction and revenue improvement.展开更多
To address the issue of resource scarcity in wireless communication, a novel dynamic call admission control scheme for wireless mobile network was proposed. The scheme established a reward computing model of call admi...To address the issue of resource scarcity in wireless communication, a novel dynamic call admission control scheme for wireless mobile network was proposed. The scheme established a reward computing model of call admission of wireless cell based on Markov decision process, dynamically optimized call admission process according to the principle of maximizing the average system rewards. Extensive simulations were conducted to examine the performance of the model by comparing with other policies in terms of new call blocking probability, handoff call dropping probability and resource utilization rate. Experimental results show that the proposed scheme can achieve better adaptability to changes in traffic conditions than existing protocols. Under high call traffic load, handoff call dropping probability and new call blocking probability can be reduced by about 8%, and resource utilization rate can be improved by 2%-6%. The proposed scheme can achieve high source utilization rate of about 85%.展开更多
Objective:This study aimed to evaluate the cost–effectiveness of durvalumab combined with tremelimumab versus sorafenib as the first-line treatment for advanced unresectable hepatocellular carcinoma(uHCC)from the per...Objective:This study aimed to evaluate the cost–effectiveness of durvalumab combined with tremelimumab versus sorafenib as the first-line treatment for advanced unresectable hepatocellular carcinoma(uHCC)from the perspective of China’s healthcare system.Methods:Utilizing data from the HIMALAYA clinical trial,a partitioned survival model was developed to simulate clinical pathways,costs,and outcomes.Incremental cost‒effectiveness ratios(ICERs)were calculated through cost‒utility analysis,with robustness assessed via one-way and probabilistic sensitivity analyses.Results:Total costs for the durvalumab‒tremelimumab regimen reached 152,729.04 USD(1.96 quality-adjusted life years,QALYs),whereas they reached 147,406.75 USD(1.48 QALYs)for sorafenib.The ICER of 11,027.79 USD per QALY remained substantially below China’s willingness-to-pay(WTP)threshold of 36,622.13 USD per QALY.Sensitivity analyses confirmed tremelimumab pricing and discount rates as primary determinants of cost‒effectiveness.Conclusion:Within China’s healthcare framework,durvalumab‒tremelimumab is cost effective as a first-line therapy for uHCC,contingent on formulary inclusion and price adjustments.展开更多
The conversion of biomass into carbonrich materials,biochar and hydrochar,has emerged as a promising strategy to solve pressing environmental challenges while supporting sustainable industrial development.A comprehens...The conversion of biomass into carbonrich materials,biochar and hydrochar,has emerged as a promising strategy to solve pressing environmental challenges while supporting sustainable industrial development.A comprehensive analysis of recent advances in the characterization and application of these materials,is provided,emphasizing their distinct production methods,physicochemical properties,and functional versatility.Biochar,typically obtained by pyrolysis at high temperatures,has a high porosity,aromaticity,and thermal stability,making it wellsuited for applications such as CO_(2)capture,electro-chemical energy storage,catalysis,and soil improvement.In contrast,hydrochar,produced by hydro-thermal carbonization in aqueous media at moderate temperatures,retains a higher number of surface functional groups and heteroatoms,offering advant-ages in aqueous-phase catalysis,pollutant adsorption,and bioremediation.The critical role of physicochemical characterization in optimizing material perform-ance is outlined,and analytical techniques including liquid nitrogen adsorption,scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectroscopy,infrared spectroscopy,Boehm titration,and thermogravimetric analysis are discussed.These show how physical-chemical characteristics such as surface area,functional group chemistry,and degree of graphitization,govern the materials’suitability for specific applications.Emerging uses in waste water treatment,biofuel production,animal feed,and advanced oxidation processes are examined,alongside their relevance to multiple UN Sustainable Development Goals,particularly in climate action,clean energy,and responsible production.The materials are versatile and can be produced on a large scale.Their performance can be fine-tuned using different production and post-treatment pro-cesses,making them key enablers in the transition to a circular,carbon-conscious economy.展开更多
基金Projects(71601015,71501013,71471014)supported by the National Natural Science Foundation of ChinaProject(2015JBM060)supported by the Fundamental Research Funds for the Central Universities,China
文摘The violation of monotonicity on reliability measures(RMs)usually makes the mathematical programming algorithms less efficient in solving the reliability-based user equilibrium(RUE)problem.The swapping algorithms provide a simple and convenient alternative to search traffic equilibrium since they are derivative-free and require weaker monotonicity.However,the existing swapping algorithms are usually based on linear swapping processes which cannot naturally avoid overswapping,and the step-size parameter update methods do not take the swapping feature into account.In this paper,we suggest a self-regulating pairwise swapping algorithm(SRPSA)to search RUE.SRPSA comprises an RM-based pairwise swapping process(RMPSP),a parameter self-diminishing operator and a termination criterion.SRPSA does not need to check the feasibility of either solutions or step-size parameter.It is suggested from the numerical analyses that SRPSA is effective and can swap to the quasi-RUE very fast.Therefore,SRPSA offers a good approach to generate initial points for those superior local search algorithms.
基金Project(2016YFB0901503) supported by National Key Research and Development Program of ChinaProjects(22075320,21875284) supported by the National Natureal Science Foundation of China。
文摘Rapid development of portable or wearable devices, which is inspired by requirements of instant messaging,health monitoring and handling official business, urgently demands more tiny, flexible and light power sources. Fibershaped batteries explored in recent years become a prospective candidate to satisfy these demands. With 1D architecture,the fiber-shaped batteries could be adapted to various deformations and integrated into soft textile and other devices.Numerous researches have been reported and achieved huge promotion. To give an overview of fiber-shaped batteries,we summarized the development of fiber-shaped batteries in this review, and discussed the structure and materials in fiber-shaped batteries. The flexibility of batteries with the potential application of the batteries was also exhibited and showed the future perspective. Finally, challenges in this field were discussed, hoping to reveal research direction towards further development of fiber-shaped batteries.
文摘CO_(2),as a greenhouse gas,has excessive emissions that lead to many environmental problems and is a rich and cheap C1 resource.Effective utilization and transformation of CO_(2)has become an important means of achieving carbon neutrality.Oxazolidinones are important intermediates in pharmaceutical chemistry that can be synthesized by carboxylation cyclization of CO_(2)with propargyl amines or cycloaddition of CO_(2)with aziridines.Owing to CO_(2)’s high stability,these reactions typically require harsh conditions,such as high temperatures or pressures.It is desirable,but challenging,to find a catalyst that can catalyze these two types of reactions under relatively mild conditions.Metal-organic frameworks(MOFs)are an emerging class of heterogeneous catalysts that with great potential in the catalytic conversion of CO_(2)to value-added products because of their attractive features,such as abundant metal active sites,inherent porosity,and easy functionalities.Herein,a unique three-dimensional(3D)MOF,{(CH_(3)NH_(2)CH_(3))_(2)[Co_(3)(BCP)_(2)]·6H_(2)O·4DMF}n(1)(H_(4)BCP:5‐(2,6‐bis(4‐carboxyphenyl)pyridin‐4‐yl)isophthalic acid;DMF:N,N'‐dimethylformamide),was synthesized using carboxylic acid ligands and cobalt salts via a solvothermal method.According to structural analysis,[Co_(3)]clusters as secondary building units(SBU)are bridged by BCP4−ligands,forming an anion framework with flu topology,and dimethylamine cations act as counter ions in the pores.The framework has rectangular channels of approximately 0.4 nm×0.9 nm along the a-axis direction,exhibiting its porous property.Infrared spectroscopy(IR)and X-ray photoelectron spectroscopy(XPS)characterizations proved the coordination interaction between the carboxyl groups in the ligands and the metal ions.The powder X-Ray diffraction(PXRD)test further confirmed the phase purity of the synthesized samples.PXRD and thermogravimetry(TG)analyses indicated that 1 possessed good solvent and thermal stabilities.The catalytic experiments revealed that 1 could effectively catalyze CO_(2)with aziridines or propargyl amines to prepare oxazolidinones.In the cycloaddition of CO_(2)with aziridines,1 can facilitate the reaction under relatively mild conditions compared to other reported MOF-based catalysts.It shows excellent universality for substrates with various substitutions on the N atom or benzene ring.Investigation of the mechanism indicated that the coordination interaction of cobalt metal sites with the nitrogen atoms of aziridines can activate the substrates.For the carboxylative cyclization of CO_(2)with propargylic amines,this catalyst also has a broad substrate scope.Control experiments and nuclear magnetic resonance(NMR)tests suggest that Lewis acid metal sites are responsible for the high catalytic efficiency achieved by activating the alkyne groups.Moreover,1 showed good reusability in both reactions.Compound 1 represents a new catalyst that enables“two birds with one stone”in the catalytic synthesis of oxazolidinones using CO_(2).
基金Project(2005CB623706) supported by the Major State Basic Research Development Program of China
文摘The influence of crystallographic orientation on the void growth in FCC crystals was numerically simulated with 3D crystal plasticity finite element by using a 3D unit cell including a spherical void, and the rate-dependent crystal plasticity theory was implemented as a user material subroutine. The results of the simulations show that crystallographic orientation has significant influence on the growth behavior of the void. Different active slip systems of the regions around the void cause the discontinuity in lattice rotation around the void, and the corner-like region is formed. In the case of the void located at grain boundary, large heterogeneous deformation occurs between the two grains, and the equivalent plastic deformation along grain boundary near the void in the case of θ=45^o （θ is the angle between grain boundary direction and X-axis） is larger than the others. Large difference of orientation factor of the two grains leads to large equivalent plastic deformation along grain boundary, and the unit cell is more likely to fail by intergranular fracture.
基金Project(20090580013) supported by the Aeronautic Science Foundation of ChinaProject(ZYGX2010J119) supported by the Fundamental Research Funds for the Central Universities,China
文摘Because the signals of global positioning system （GPS） satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. In this case, the receiver autonomous integrity monitoring （RAIM） method earmot exclude faulty satellite. In order to improve the performance of RAIM method and obtain the reliable positioning results with five satellites, the series of receiver clock bias （RCB） is regarded as one useful satellite and used to aid RAIM method. From the point of nonlinear series, a grey-Markov model for predicting the RCB series based on grey theory and Markov chain is presented. And then the model is used for aiding RAIM method in order to exclude faulty satellite. Experimental results demonstrate that the prediction model is fit for predicting the RCB series, and with the clock-based RAIM method the faulty satellite can be correctly excluded and the positioning precision of GPS receiver can be improved for the case where there are only five useful satellites.
基金Projects(51378119,51578150)supported by the National Natural Science Foundation of China
文摘Advanced traveler information systems （ATIS） can not only improve drivers＇ accessibility to the more accurate route travel time information, but also can improve drivers＇ adaptability to the stochastic network capacity degradations. In this paper, a mixed stochastic user equilibrium model was proposed to describe the interactive route choice behaviors between ATIS equipped and unequipped drivers on a degradable transport network. In the proposed model the information accessibility of equipped drivers was reflected by lower degree of uncertainty in their stochastic equilibrium flow distributions, and their behavioral adaptability was captured by multiple equilibrium behaviors over the stochastic network state set. The mixed equilibrium model was formulated as a fixed point problem defined in the mixed route flows, and its solution was achieved by executing an iterative algorithm. Numerical experiments were provided to verify the properties of the mixed network equilibrium model and the efficiency of the iterative algorithm.
基金Project(2013BAB02B05)supported by National Science and Technology Support Program of ChinaProject(2013JSJJ029)supported by the Teacher Fund of Central South University,ChinaProjects(51074177,41372278)supported by the National Natural Science Foundation of China
文摘Due to the influence of joint fissure, mining intensity, designed slope angle, underground water and rainfall, the failure process of mine slope project is extremely complicated. The current safety factor calculation method has certain limitations, and it would be difficult to obtain the reliability index when the performance function of reliability analysis is implicit or has high order terms. Therefore, with the help of the logistic equation of chaos theory, a new algorithm of mine slope reliability based on limiting state hyper-plane is proposed. It is shown that by using this new reliability algorithm the calculation of partial derivative of performance function is avoided, and it has the advantages of being simple and easy to program. The new algorithm is suitable for calculating the reliability index of complex performance function containing high order terms. Furthermore, the limiting state hyper-plane models of both simplified Bishop's and Janbu's method adaptive to slope project are obtained, and have achieved satisfactory effect in the study of mine slope stability in Dexing copper open pit.
基金Project(41274012) supported by the National Natural Science Foundation of China
文摘Chloride-induced corrosion of the reinforcement is considered as one of the major mechanisms resulting in the reduction of structural resistance of reinforced concrete structural elements located in marine and other aggressive environments. A study of reinforced concrete structures located at the Fangcheng dock in the Beibu Gulf port, China, was present. The result from field survey indicates that the concrete cover depth and chloride diffusion coefficient fit best normal distribution and lognormal distribution, respectively. The service life of structure is about 55 a, while initiation time is 45 a. Sensitivity analysis indicates that the most influential factor of the structure service life prediction is concrete cover, followed by diffusion coefficient, diffusion decay index, critical chloride concentration, surface chloride concentration, current density and localized pitting corrosion. Finally, the effects of diffusion decay index and critical chloride concentration on structure service life prediction are discussed.
基金Foundation item： Project（2011CB707201） supported by the National Basic Research Program of China Project（10JJ5058） supported by the Natural Science Foundation of Hunan Province, China
文摘To improve the energy utilization efficiency of internal combustion （IC） engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exergy balance model was built. The working processes of gasoline engine were simulated by using the GT-power. In this way, the required parameters were calculated and then gasoline engine exergy balance was obtained by programming on computer. On this basis, the influences of various parameters on exergy balance were analyzed. Results show that, the proportions of various forms of exergy in gasoline engine from high to low are irreversible loss, effective work, exhaust gas exergy and heat transfer exergy. Effective exergy proportion fluctuates with cylinder volumetric efficiency at full load, while it always increases with break mean effective pressure （BMEP） at part load. Exhaust gas exergy proportion is more sensitive to speed, and it increases with speed increasing except at the highest speed. The lower proportion of heat transfer exergy appears at high speed and high load. Irreversible loss is mainly influenced by load. At part load, higher BMEP results in lower proportion of irreversible loss; at full load, the proportion of irreversible loss changes little except at the highest speed.
基金Project(2010QZZD021)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2015F024)supported by China Railway Science and Technology Research Development Program
文摘In order to apply overbooking idea in Chinese railway freight industry to improve revenue, a Markov decision process(dynamic programming) model for railway freight reservation was formulated and the overbooking limit level was proposed as a control policy. However, computing the dynamic programming treatment needs six nested loops and this will be burdensome for real-world problems. To break through the calculation limit, the properties of value function were analyzed and the overbooking protection level was proposed to reduce the calculating quantity. The simulation experiments show that the overbooking protection level for the lower-fare class is higher than that for the higher-fare class, so the overbooking strategy is nested by fare class. Besides, by analyzing the influence on the overbooking strategy of freight arrival probability and cancellation probability, the proposed approach is efficient and also has a good application prospect in reality. Also, compared with the existing reservation(FCFS), the overbooking strategy performs better in the fields of vacancy reduction and revenue improvement.
基金Project(60873082) supported by the National Natural Science Foundation of ChinaProject(09C794) supported by the Natural Science Foundation of Education Department of Hunan Province, China+1 种基金Project (S2008FJ3078) supported by the Science and Technology Program Foundation of Hunan Province, ChinaProject(07JJ6109) supported by the Natural Science Foundation of Hunan Province, China
文摘To address the issue of resource scarcity in wireless communication, a novel dynamic call admission control scheme for wireless mobile network was proposed. The scheme established a reward computing model of call admission of wireless cell based on Markov decision process, dynamically optimized call admission process according to the principle of maximizing the average system rewards. Extensive simulations were conducted to examine the performance of the model by comparing with other policies in terms of new call blocking probability, handoff call dropping probability and resource utilization rate. Experimental results show that the proposed scheme can achieve better adaptability to changes in traffic conditions than existing protocols. Under high call traffic load, handoff call dropping probability and new call blocking probability can be reduced by about 8%, and resource utilization rate can be improved by 2%-6%. The proposed scheme can achieve high source utilization rate of about 85%.
基金supported by the National Natural Science Foundation of China(12231017,72171216,12171449)the National Key R&D Program of China(2022YFA1003803)+1 种基金the Fundamental Research Funds for the Central Universities(WK3470000027)the Innovative Development Funds of Anhui Province Federation of Social Sciences(2022CX081).
文摘Objective:This study aimed to evaluate the cost–effectiveness of durvalumab combined with tremelimumab versus sorafenib as the first-line treatment for advanced unresectable hepatocellular carcinoma(uHCC)from the perspective of China’s healthcare system.Methods:Utilizing data from the HIMALAYA clinical trial,a partitioned survival model was developed to simulate clinical pathways,costs,and outcomes.Incremental cost‒effectiveness ratios(ICERs)were calculated through cost‒utility analysis,with robustness assessed via one-way and probabilistic sensitivity analyses.Results:Total costs for the durvalumab‒tremelimumab regimen reached 152,729.04 USD(1.96 quality-adjusted life years,QALYs),whereas they reached 147,406.75 USD(1.48 QALYs)for sorafenib.The ICER of 11,027.79 USD per QALY remained substantially below China’s willingness-to-pay(WTP)threshold of 36,622.13 USD per QALY.Sensitivity analyses confirmed tremelimumab pricing and discount rates as primary determinants of cost‒effectiveness.Conclusion:Within China’s healthcare framework,durvalumab‒tremelimumab is cost effective as a first-line therapy for uHCC,contingent on formulary inclusion and price adjustments.
基金the support of the CERENA(FCT-UIDB/04028/2025 and FCTUIDP/04028/2025)VALORIZA–Research Centre for Endogenous Resource Valorization(FCT-UID/05064/2025)。
文摘The conversion of biomass into carbonrich materials,biochar and hydrochar,has emerged as a promising strategy to solve pressing environmental challenges while supporting sustainable industrial development.A comprehensive analysis of recent advances in the characterization and application of these materials,is provided,emphasizing their distinct production methods,physicochemical properties,and functional versatility.Biochar,typically obtained by pyrolysis at high temperatures,has a high porosity,aromaticity,and thermal stability,making it wellsuited for applications such as CO_(2)capture,electro-chemical energy storage,catalysis,and soil improvement.In contrast,hydrochar,produced by hydro-thermal carbonization in aqueous media at moderate temperatures,retains a higher number of surface functional groups and heteroatoms,offering advant-ages in aqueous-phase catalysis,pollutant adsorption,and bioremediation.The critical role of physicochemical characterization in optimizing material perform-ance is outlined,and analytical techniques including liquid nitrogen adsorption,scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectroscopy,infrared spectroscopy,Boehm titration,and thermogravimetric analysis are discussed.These show how physical-chemical characteristics such as surface area,functional group chemistry,and degree of graphitization,govern the materials’suitability for specific applications.Emerging uses in waste water treatment,biofuel production,animal feed,and advanced oxidation processes are examined,alongside their relevance to multiple UN Sustainable Development Goals,particularly in climate action,clean energy,and responsible production.The materials are versatile and can be produced on a large scale.Their performance can be fine-tuned using different production and post-treatment pro-cesses,making them key enablers in the transition to a circular,carbon-conscious economy.
