The increasing intelligence of power systems is transforming distribution networks into Cyber-Physical Distribution Systems(CPDS).While enabling advanced functionalities,the tight interdependence between cyber and phy...The increasing intelligence of power systems is transforming distribution networks into Cyber-Physical Distribution Systems(CPDS).While enabling advanced functionalities,the tight interdependence between cyber and physical layers introduces significant security challenges and amplifies operational risks.To address these critical issues,this paper proposes a comprehensive risk assessment framework that explicitly incorporates the physical dependence of information systems.A Bayesian attack graph is employed to quantitatively evaluate the likelihood of successful cyber attacks.By analyzing the critical scenario of fault current path misjudgment,we define novel system-level and node-level risk coupling indices to preciselymeasure the cascading impacts across cyber and physical domains.Furthermore,an attack-responsive power recovery optimization model is established,integrating DistFlowbased physical constraints and sophisticated modeling of information-dependent interference.To enhance resilience against varying attack scenarios,a defense resource allocation model is constructed,where the complex Mixed-Integer Nonlinear Programming(MINLP)problem is efficiently linearized into a Mixed-Integer Linear Programming(MILP)formulation.Finally,to mitigate the impact of targeted attacks,the optimal deployment of terminal defense resources is determined using a Stackelberg game-theoretic approach,aiming to minimize overall system risk.The robustness and effectiveness of the proposed integrated framework are rigorously validated through extensive simulations under diverse attack intensities and defense resource constraints.展开更多
Biochar has been widely recognized as a promising solid CO_(2)adsorbent with economic and ecological benefits.Industrial CO_(2)emissions originate from diverse sources,while the pore structure and chemical functional ...Biochar has been widely recognized as a promising solid CO_(2)adsorbent with economic and ecological benefits.Industrial CO_(2)emissions originate from diverse sources,while the pore structure and chemical functional groups of biochar exhibit varying degrees of influence on CO_(2)adsorption and separation performance under different adsorption conditions.Therefore,exploring the matching relationship between the physicochemical properties of biochar and its adsorption and separation performance at different adsorption conditions is essential for the development and optimization of carbon-based adsorbents.This study selected the high-performance extreme gradient boosting(XGB)algorithm from various algorithms and utilized it to develop CO_(2),N_(2),CH_(4)adsorption prediction models.Based on this,coupled prediction models were developed for CO_(2)/N_(2)and CO_(2)/CH_(4)adsorption selectivity.Furthermore,feature importance and partial dependence analysis were performed using SHAP values.The results indicate that during CO_(2)adsorption,the influence of the pore structure of biochar outweighs that of its chemical composition.Specifically,the pore structure of 0.4–0.6 nm is the most important property influencing CO_(2)adsorption at low and medium pressure(0–0.6 bar),and the pore structure of 0.6–0.8 nm,as well as the specific surface area contribute the most at high pressure(0.6–1 bar).During CO_(2)selective separation,the CO_(2)/N_(2)mixture is primarily separated through the selective adsorption of CO_(2)by nitrogen functional groups.In contrast,for CO_(2)/CH_(4)mixtures,pore structure<1 nm plays a more critical role in determining adsorption selectivity.In addition,molecular simulation studies further revealed the adsorption filling mechanisms of CO_(2)molecules within different pore sizes and functional groups.Finally,nitrogen-doped biochar was synthesized using de-alkalize lignin as the precursor,KOH as the activating agent,and urea as the nitrogen dopant.CO_(2),N_(2),and CH_(4)isothermal adsorption experiments were conducted,and the experimental results confirmed that the developed prediction models exhibit high accuracy(R^(2)>0.9).展开更多
On-site measurements of volatile organic compounds(VOCs)in different streams of flue gas were carried out on a real coal-fired power plant using sampling bags and SUMMA canisters to collect gas samples,filters to coll...On-site measurements of volatile organic compounds(VOCs)in different streams of flue gas were carried out on a real coal-fired power plant using sampling bags and SUMMA canisters to collect gas samples,filters to collect particle samples.Gas chromatography-flame ionization detector/mass spectrometry and gas chromatography-mass spectrometry was the offline analysis method.We found that the total mass concentration of the tested 102 VOC species at the outlet of wet flue gas desulfuration device was(13456±47)μg·m^(-3),which contained aliphatic hydrocarbons(57.9%),aromatic hydrocarbons(26.8%),halogen-containing species(14.5%),and a small amount of oxygen-containing and nitrogencontaining species.The most abundant species were 1-hexene,n-hexane and 2-methylpentane.The top ten species in terms of mass fraction(with a total mass fraction of 75.3%)were mainly hydrocarbons with a carbon number of 6 or higher and halogenated hydrocarbons with a lower carbon number.The mass concentration of VOC species in the particle phase was significantly lower than that in the gas phase.The change of VOC mass concentrations along the air pollution control devices indicates that conventional pollutant control equipment had a limited effect on VOC reduction.Ozone formation potential calculations showed that aromatic hydrocarbons contributed the highest ozone formation(46.4%)due to their relatively high mass concentrations and MIR(maximum increment reactivity)values.展开更多
A method of measuring the interactions in a multivariable control sys-tem(MVCS)in time domain is defined in this paper.An intelligent decoupling com-pensator is designed in terms of the concept of fuzzy control,so tha...A method of measuring the interactions in a multivariable control sys-tem(MVCS)in time domain is defined in this paper.An intelligent decoupling com-pensator is designed in terms of the concept of fuzzy control,so that the auto-tuningof controllers’ parameters in a 2×2 MVCS can be turned into that of two independentsingle-loop control systems(SLCS).The method presented in the paper has success-fully been used in a simulation experiment on the automatic tuning of a coordinatedcontrol system(CCS)in the drum-boiler turbogenerating unit(DBTU)and the simu-lation results axe satisfactory.展开更多
This work focuses on the best financial resources allocation to define a wind power plant portfolio, considering a set of feasible sites. To accomplish the problem formulation and solution, the first step was to estab...This work focuses on the best financial resources allocation to define a wind power plant portfolio, considering a set of feasible sites. To accomplish the problem formulation and solution, the first step was to establish a long-term wind series reconstruction methodology for generating scenarios of wind energy, applying it to study five different locations of the Brazilian territory. Secondly, a risk-averse stochastic optimization model was implemented and used to define the optimal wind power plant selection </span><span style="font-family:Verdana;">that</span><span style="font-family:Verdana;"> maximize</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> the portfolio financial results, considering an investment budget constraint. In a sequence, a case study was developed to illustrate a practical situation of applying the methodology to the portfolio selection problem, considering five wind power plant</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> options. </span><span style="font-family:Verdana;">The case</span><span style="font-family:Verdana;"> study was supported by the proposed optimization model, using the scenarios of generation created by the reconstruction methodology. The obtained results show the model performance in terms of defining the best financial resources allocation considering the effect of the complementarity between sites, making it feasible to select the optimal set of wind power plants, characterizing a wind plant optimal portfolio that takes into account the budget constraint. The adopted methodology makes it possible to realize that the diversification of the portfolio depends on the investor risk aversion. Although applied to the Brazilian case, this model can be customized to solve a similar problem worldwide.展开更多
Cellular mobile technology has witnessed tremendous growth in recent times.One of the challenges facing the operators to extend the coverage of the networks to meet the rising demand for cellular mobile services is th...Cellular mobile technology has witnessed tremendous growth in recent times.One of the challenges facing the operators to extend the coverage of the networks to meet the rising demand for cellular mobile services is the power sources used to supply cellular towers with energy,especially in remote.Thus,switch from the conventional sources of energy to a greener and sustainable power model became a target of the academic and industrial sectors in many fields;one of these important fields is the telecommunication sector.Accordingly,this study aims to find the optimum sizing and technoeconomic investigation of a solar photovoltaic scheme to deploy cellular mobile technology infrastructure cleanly and sustainably.The optimal solarpowered system is designed by employing the energy-balance procedures of the HOMER software tool.The problem objective is considered in terms of cost,but the energy system is constrained to meet the power demand reliably.Process simulations were performed to determine the optimum sizing,performance and monetary cost of the power system,using long-term meteorological datasets for a case study site with defined longitude(31◦25E)and latitude(30◦06N).From the observed results,the total net present cost(NPC)of the proposed system is$28,187.Indeed,these outcomes can provide profound economic,technical,and ecological benefits to cellular operators.It also ensures a sizeable reduction in greenhouse gas that supports sustainable green wireless network(WN)deployment in remote areas.展开更多
The development of the capabilities of computational tools has created up new possibilities for the effective use of a number of classical mathematical methods and algorithms for solving many important problems in the...The development of the capabilities of computational tools has created up new possibilities for the effective use of a number of classical mathematical methods and algorithms for solving many important problems in the power engineering. In particular, a set of algorithms are developed to optimize the modes of electric power systems based on genetic algorithms. At the same time, the issues of taking into account functional constraints in solving such problems by genetic algorithms need to be improved. In accordance with it in this article the problems of taking into account of different constraints in optimization of modes of power systems using genetic algorithms are considered. The algorithm of optimization by genetic algorithm taking into account of functional constraints in forms of equality and inequality by penalty functions is proposed. The results of research of proposed algorithm’s efficiency in example of optimization of mode of power system with 8 buses, 4 thermal power plants and 3 transmission lines with controlled power flow are presented.展开更多
In this paper a new market based analytical model is proposed for optimal placement of Wind Turbines (WTs) in power systems. In addition to wind turbines, thermal units (THUs) and Pumped Storage Hydro Power Plants (PS...In this paper a new market based analytical model is proposed for optimal placement of Wind Turbines (WTs) in power systems. In addition to wind turbines, thermal units (THUs) and Pumped Storage Hydro Power Plants (PSHPPs) owners participate in power market. Objective function is defined as participants’ social welfare achieved from power pool and ancillary markets in yearly horizon. Wind turbines have been modeled by probability-generation tree scenarios based on statistical information. We concentrate on investment profits of WTs numbers and its generation capacity beside to PSHPPs and THUs power plants in power systems due to increase in high flexible tools for Independent system operator into the planning and operation planning time interval. For effectiveness evaluation of proposed model, simulation studies are applied on 14-Bus IEEE test power system.展开更多
RES （renewable energy sources）, such as wind and photovoltaic power plants, suffer from their stochastic nature that is why their behavior on market is very delicate. In order to diversify risk, a concept of VPP （v...RES （renewable energy sources）, such as wind and photovoltaic power plants, suffer from their stochastic nature that is why their behavior on market is very delicate. In order to diversify risk, a concept of VPP （virtual power plant） has been developed. The VPP is composed of several RES, from which at least one of them is fully controllable. Because the production of noncontrollable RES can not be forecasted perfectly, therefore an optimal dispatch schedule within VPP is needed. To address this problem, an APSO （accelerated particle swarm optimization） is used to solve the constrained optimal dispatch problem within VPP. The experimental results show that the proposed optimization method provides high quality solutions while meeting constraints.展开更多
The paper presents results from a study of a series-connected single-phase APF （active power filter） with a control system based on hysteresis control, both with and without limitation of the maximum switching frequ...The paper presents results from a study of a series-connected single-phase APF （active power filter） with a control system based on hysteresis control, both with and without limitation of the maximum switching frequency. The general purpose of the series APF is to eliminate the low order harmonics of the source （grid） voltage. The filter operation at limited and unlimited maximum switching frequency is explained and it is described using building blocks and time diagrams illustrating the tracking down of the reference curve. Waveforms from the computer simulation and waveforms from the experimental tests of the filter are presented also for the two situations. Operations at limited and unlimited maximum switching frequency are compared regarding the quality of the voltage across the load, the complexity of the implementation of the control system, and the electromagnetic compatibility. The investigation proved capability of the series APF to achieve its general purpose using the hysteresis control methods studied （limited and unlimited switching frequency）.展开更多
This study explores the influence of rotor blade angle on stall inception in an axial fan by means of numerical simulations grounded in the Reynolds-Averaged Navier-Stokes(RANS)equations and the Realizable k-εturbule...This study explores the influence of rotor blade angle on stall inception in an axial fan by means of numerical simulations grounded in the Reynolds-Averaged Navier-Stokes(RANS)equations and the Realizable k-εturbulence model.By analyzing the temporal behavior of the outlet static pressure,along with the propagation velocity of stall inception,the research identifies distinct patterns in the development of stall.The results reveal that stall inception originates in the second rotor impeller.At a blade angle of 27°,the stall inception follows a modal wave pattern,while in all other cases,it assumes the form of spike-type stall.The flow field associated with spike stall inception demonstrates a relatively uniform gradient in the radial direction,whereas the modal wave stall case displays a distinctive“L”-shaped propagation feature.At blade angles of multiple stall inceptions are observed.-9°and-18°,These phenomena initiate at the blade’s leading edge,propagate along both axial and radial directions,and transition dynamically between single and multiple inception states.展开更多
Enhancing the fermentation efficiency of waste in waste warehouses is pivotal for accelerating the pyrolysis process and minimizing harmful gas emissions.This study proposes an integrated approach,combining hot air in...Enhancing the fermentation efficiency of waste in waste warehouses is pivotal for accelerating the pyrolysis process and minimizing harmful gas emissions.This study proposes an integrated approach,combining hot air injection with dual atomizing nozzles,for the thermal treatment of waste piles.Numerical simulations are employed to investigate the influence of various parameters,namely,nozzle height,nozzle tilt angle,inlet air velocity and air temperature,on the droplet diffusion process,spread area,droplet temperature,and droplet size distribution.The results show that reducing the nozzle height increases the temperature of droplets upon their deposition on the waste pile.Specifically,when the nozzle height is lowered to 1.5 m,the temperature of the droplets reaching the waste pile is 1℃higher than when the nozzle height is set at 2 m.Furthermore,an increase in the nozzle tilt angle expands the overlapping heating area.For instance,when the nozzle angle is increased from 15°to 30°,the overlapping spread area expands by 3.21 m2.Additionally,increasing the inlet air velocity enhances the droplet diffusion range.At an air velocity of 2 m/s,the droplet diffusion range grows to 14.4 m,representing a 6.7%increase compared to the nowind condition.While the average droplet diameter decreases to 1.53 mm,the droplet temperature decreases by 1℃.Moreover,the droplet temperature is found to become smaller as the ambient temperature inside the waste warehouse declines.Specifically,a 5℃reduction in the ambient temperature results in a 1℃decrease in the average temperature of the atomized droplets.The study concludes that a nozzle height of 1.5 m and a nozzle tilt angle of 30°effectively meet practical heating requirements.展开更多
Modern electric traction networks(ETN)are equipped with automated systems for commercial accounting of power consumption(ASCAPC),which allows solving properly the problems of enhancing the energy efficiency of transpo...Modern electric traction networks(ETN)are equipped with automated systems for commercial accounting of power consumption(ASCAPC),which allows solving properly the problems of enhancing the energy efficiency of transportation processes.Energy efficiency of ETNs is defined as the amount of power losses in ETN components:overhead catenary systems and traction transformers.Due to the instability of traction loads and changes in their location in space,the electric traction network is different from the general network.It is necessary to develop an approach for loss analysis in traction networks and in transformers of traction substations.To solve this prob-lem,a balance-based technique for power loss calculation in traction networks based on ASCAPC data is proposed.First,the balance-based technique presented here breaks down the power consumption of the train by source.Then,calculates technical power losses in 25 and 225 kV traction networks as well as in traction transformers.Last,the technique is implemented in the form of an algorithm tested on real-life data and it is ready for practical use.展开更多
One of the solutions to the global warming risk and other climate issues is to concentrate on research and development of utilizing biomass as a fossil fuel alternative.The current estimate of cotton residue waste in ...One of the solutions to the global warming risk and other climate issues is to concentrate on research and development of utilizing biomass as a fossil fuel alternative.The current estimate of cotton residue waste in the world is about 50 million tons.This massive volume of biomass waste should be turned into clean energy to avert burning the stalks in open fields after cotton harvesting.Therefore,harmful emissions such as CO_(2) will be reduced.This study aims to investigate the published literature to comprehend the bioenergy production from the thermal treatment of cotton stalks,including combustion,pyrolysis,carbonization,torrefaction,liquefaction,and gasification.Furthermore,the future outlook,utilization,and prospective challenges of agricultural biomass for biofuel production are discussed.According to the literature,biochar and bio-oil derived from cotton stalks have high heating values of about 27.5 and 37.2 MJ·kg~(–1),respectively.These values are double those of cotton stalk raw materials,which make it a good candidate for bioenergy production.This article offers valuable insight into cotton stalk utilization via thermochemical treatment and provides a solid reference for researchers,policymakers,and other stakeholders in this field.展开更多
The target of this paper is the performance-based diagnostics of a gas turbine for the automated early detection of components malfunctions. The paper proposes a new combination of multiple methodologies for the perfo...The target of this paper is the performance-based diagnostics of a gas turbine for the automated early detection of components malfunctions. The paper proposes a new combination of multiple methodologies for the performance-based diagnostics of single and multiple failures on a two-spool engine. The aim of this technique is to combine the strength of each methodology and provide a high success rate for single and multiple failures with the presence of measurement malfunctions. A combination of KF(Kalman Filter), ANN(Artificial Neural Network) and FL(Fuzzy Logic) is used in this research in order to improve the success rate, to increase the flexibility and the number of failures detected and to combine the strength of multiple methods to have a more robust solution. The Kalman filter has in his strength the measurement noise treatment, the artificial neural network the simulation and prediction of reference and deteriorated performance profile and the fuzzy logic the categorization flexibility, which is used to quantify and classify the failures. In the area of GT(Gas Turbine) diagnostics, the multiple failures in combination with measurement issues and the utilization of multiple methods for a 2-spool industrial gas turbine engine has not been investigated extensively.This paper reports the key contribution of each component of the methodology and brief the results in the quantification and classification success rate. The methodology is tested for constant deterioration and increasing noise and for random deterioration. For the random deterioration and nominal noise of 0.4%, in particular, the quantification success rate is above 92.0%, while the classification success rate is above 95.1%. Moreover, the speed of the data processing(1.7 s/sample)proves the suitability of this methodology for online diagnostics.展开更多
The aerodynamic design of a rigid-flexible coupling profile is the decisive factor for the flow-field quality of a supersonic free jet wind tunnel nozzle, and its mechanic dynamic features are the key for engineering ...The aerodynamic design of a rigid-flexible coupling profile is the decisive factor for the flow-field quality of a supersonic free jet wind tunnel nozzle, and its mechanic dynamic features are the key for engineering implementation of continuous Mach number regulations. To fulfill the requirements of a free jet inlet/engine compatibility test within a wide simulation envelop, both uniform flow-fields of continuous acceleration and deceleration are necessary. In this paper, the aerodynamic design methods of an expansion wall and machinery implementation plan for the halfflexible single jack nozzle were researched. The profile control in nozzle flexible plate design was studied with a rigid-flexible coupling method. Design and calculations were performed with the help of numerical simulation. The technique of axial free stretching of the flexible plate was used to improve the matching performance between the designed elasticity profile and the theoretical one, and the rigid-flexible coupling structure was calibrated by wind tunnel tests. Results indicate that the flexible plate aerodynamic design method used here is effective and feasible. Via rigidflexible coupling design, the flexible plate agrees with the rigid body very well, and continuous Mach number changes can be achieved during the tests. The nozzle’s exit flow-field uniformity meets the requirements of China Military Standard(GJB).展开更多
The heat transfer coefficient in a multidimensional heat conduction problem is obtained from the solution of the inverse heat conduction problem based on the thermographic temperature measurement. The modified one-dim...The heat transfer coefficient in a multidimensional heat conduction problem is obtained from the solution of the inverse heat conduction problem based on the thermographic temperature measurement. The modified one-dimensional correction method （MODCM）, along with the finite volume method, is employed for both two- and three-dimensional inverse problems. A series of numerical experiments are conducted in order to verify the effectiveness of the method. In addition, the effect of the temperature measurement error, the ending criterion of the iteration, etc. on the result of the inverse problem is investigated. It is proved that the method is a simple, stable and accurate one that can solve successfully the inverse heat conduction problem.展开更多
In order to investigate the feasibility of sequential removal NO and SO2 using non-thermal plasma and adsorbent simultaneously, the removal of NO and SO2 from dry gas stream （NO/SO2/N2/O2） with very little O2 using ...In order to investigate the feasibility of sequential removal NO and SO2 using non-thermal plasma and adsorbent simultaneously, the removal of NO and SO2 from dry gas stream （NO/SO2/N2/O2） with very little O2 using non-thermal plasma was investigated using a coaxial dielectric barrier discharge. Comparative experiments were carried out in the dry gas stream with and without Ar respectively at O2 concentration of 0.1%. The results showed that NO could be removed remarkably and it would be enhanced in the presence of Ar in the dry gas stream. It seems that SO2 could not be removed unless there is Ar in the dry gas stream. The mechanism of removal of NO and SO2 in the dry gas stream was discussed.展开更多
A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is ba...A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is based on the assumptions that the difference of temperature along the longitudinal axis of the boiler drum is negligible with changes only in the radial direction and the circumferential direction, and that the outer surface of drum is thermaUy insulated. Combining this model with the control-volume method provides temperatures at different points on a cross-section of the drum. With the temperature data, the stresses and the life expectancy of the boiler drum are derived according to the ASME code. Applying this method to the cold start-up process of a 300 MW boiler demonstrated the absence of errors caused by the boundary condition assumptions on the inner surface of the drum and testified that the method is an applicable technique for the online stress monitoring and fatigue life analysis of boiler drums.展开更多
基金supported by China Southern Power Grid Company Limited(066500KK52222006).
文摘The increasing intelligence of power systems is transforming distribution networks into Cyber-Physical Distribution Systems(CPDS).While enabling advanced functionalities,the tight interdependence between cyber and physical layers introduces significant security challenges and amplifies operational risks.To address these critical issues,this paper proposes a comprehensive risk assessment framework that explicitly incorporates the physical dependence of information systems.A Bayesian attack graph is employed to quantitatively evaluate the likelihood of successful cyber attacks.By analyzing the critical scenario of fault current path misjudgment,we define novel system-level and node-level risk coupling indices to preciselymeasure the cascading impacts across cyber and physical domains.Furthermore,an attack-responsive power recovery optimization model is established,integrating DistFlowbased physical constraints and sophisticated modeling of information-dependent interference.To enhance resilience against varying attack scenarios,a defense resource allocation model is constructed,where the complex Mixed-Integer Nonlinear Programming(MINLP)problem is efficiently linearized into a Mixed-Integer Linear Programming(MILP)formulation.Finally,to mitigate the impact of targeted attacks,the optimal deployment of terminal defense resources is determined using a Stackelberg game-theoretic approach,aiming to minimize overall system risk.The robustness and effectiveness of the proposed integrated framework are rigorously validated through extensive simulations under diverse attack intensities and defense resource constraints.
基金supported by the Fundamental Research Funds for the Central Universities(No.2025JC008)the National Natural Science Foundation of China(grant number 52176105)+2 种基金the Science and Technology Project of Hebei Education Department-China(BJK2022063)the Hebei Natural Science Foundation-China(grant number E2025502038)the Funding Program for Cultivating Innovative Abilities of Graduate Students in Hebei Province of China(CXZZBS2025184).
文摘Biochar has been widely recognized as a promising solid CO_(2)adsorbent with economic and ecological benefits.Industrial CO_(2)emissions originate from diverse sources,while the pore structure and chemical functional groups of biochar exhibit varying degrees of influence on CO_(2)adsorption and separation performance under different adsorption conditions.Therefore,exploring the matching relationship between the physicochemical properties of biochar and its adsorption and separation performance at different adsorption conditions is essential for the development and optimization of carbon-based adsorbents.This study selected the high-performance extreme gradient boosting(XGB)algorithm from various algorithms and utilized it to develop CO_(2),N_(2),CH_(4)adsorption prediction models.Based on this,coupled prediction models were developed for CO_(2)/N_(2)and CO_(2)/CH_(4)adsorption selectivity.Furthermore,feature importance and partial dependence analysis were performed using SHAP values.The results indicate that during CO_(2)adsorption,the influence of the pore structure of biochar outweighs that of its chemical composition.Specifically,the pore structure of 0.4–0.6 nm is the most important property influencing CO_(2)adsorption at low and medium pressure(0–0.6 bar),and the pore structure of 0.6–0.8 nm,as well as the specific surface area contribute the most at high pressure(0.6–1 bar).During CO_(2)selective separation,the CO_(2)/N_(2)mixture is primarily separated through the selective adsorption of CO_(2)by nitrogen functional groups.In contrast,for CO_(2)/CH_(4)mixtures,pore structure<1 nm plays a more critical role in determining adsorption selectivity.In addition,molecular simulation studies further revealed the adsorption filling mechanisms of CO_(2)molecules within different pore sizes and functional groups.Finally,nitrogen-doped biochar was synthesized using de-alkalize lignin as the precursor,KOH as the activating agent,and urea as the nitrogen dopant.CO_(2),N_(2),and CH_(4)isothermal adsorption experiments were conducted,and the experimental results confirmed that the developed prediction models exhibit high accuracy(R^(2)>0.9).
基金supported by the National Natural Science Foundation of China(61203129,61174038,61473151,51507080)the Fundamental Research Funds for the Central Universities(30915011104,30920130121010,30920140112005)
基金funded by the National Natural Science Foundation of China(52006079)the Natural Science Foundation of Hubei Province(2020CFB247)the National Key Research and Development Program of China(2018YFB0605201)。
文摘On-site measurements of volatile organic compounds(VOCs)in different streams of flue gas were carried out on a real coal-fired power plant using sampling bags and SUMMA canisters to collect gas samples,filters to collect particle samples.Gas chromatography-flame ionization detector/mass spectrometry and gas chromatography-mass spectrometry was the offline analysis method.We found that the total mass concentration of the tested 102 VOC species at the outlet of wet flue gas desulfuration device was(13456±47)μg·m^(-3),which contained aliphatic hydrocarbons(57.9%),aromatic hydrocarbons(26.8%),halogen-containing species(14.5%),and a small amount of oxygen-containing and nitrogencontaining species.The most abundant species were 1-hexene,n-hexane and 2-methylpentane.The top ten species in terms of mass fraction(with a total mass fraction of 75.3%)were mainly hydrocarbons with a carbon number of 6 or higher and halogenated hydrocarbons with a lower carbon number.The mass concentration of VOC species in the particle phase was significantly lower than that in the gas phase.The change of VOC mass concentrations along the air pollution control devices indicates that conventional pollutant control equipment had a limited effect on VOC reduction.Ozone formation potential calculations showed that aromatic hydrocarbons contributed the highest ozone formation(46.4%)due to their relatively high mass concentrations and MIR(maximum increment reactivity)values.
文摘A method of measuring the interactions in a multivariable control sys-tem(MVCS)in time domain is defined in this paper.An intelligent decoupling com-pensator is designed in terms of the concept of fuzzy control,so that the auto-tuningof controllers’ parameters in a 2×2 MVCS can be turned into that of two independentsingle-loop control systems(SLCS).The method presented in the paper has success-fully been used in a simulation experiment on the automatic tuning of a coordinatedcontrol system(CCS)in the drum-boiler turbogenerating unit(DBTU)and the simu-lation results axe satisfactory.
文摘This work focuses on the best financial resources allocation to define a wind power plant portfolio, considering a set of feasible sites. To accomplish the problem formulation and solution, the first step was to establish a long-term wind series reconstruction methodology for generating scenarios of wind energy, applying it to study five different locations of the Brazilian territory. Secondly, a risk-averse stochastic optimization model was implemented and used to define the optimal wind power plant selection </span><span style="font-family:Verdana;">that</span><span style="font-family:Verdana;"> maximize</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> the portfolio financial results, considering an investment budget constraint. In a sequence, a case study was developed to illustrate a practical situation of applying the methodology to the portfolio selection problem, considering five wind power plant</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> options. </span><span style="font-family:Verdana;">The case</span><span style="font-family:Verdana;"> study was supported by the proposed optimization model, using the scenarios of generation created by the reconstruction methodology. The obtained results show the model performance in terms of defining the best financial resources allocation considering the effect of the complementarity between sites, making it feasible to select the optimal set of wind power plants, characterizing a wind plant optimal portfolio that takes into account the budget constraint. The adopted methodology makes it possible to realize that the diversification of the portfolio depends on the investor risk aversion. Although applied to the Brazilian case, this model can be customized to solve a similar problem worldwide.
基金This research was supported by the Korea Electric Power Corporation(Grant number:R19XO01-37)This research was also supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(2020R1A2C1004743).
文摘Cellular mobile technology has witnessed tremendous growth in recent times.One of the challenges facing the operators to extend the coverage of the networks to meet the rising demand for cellular mobile services is the power sources used to supply cellular towers with energy,especially in remote.Thus,switch from the conventional sources of energy to a greener and sustainable power model became a target of the academic and industrial sectors in many fields;one of these important fields is the telecommunication sector.Accordingly,this study aims to find the optimum sizing and technoeconomic investigation of a solar photovoltaic scheme to deploy cellular mobile technology infrastructure cleanly and sustainably.The optimal solarpowered system is designed by employing the energy-balance procedures of the HOMER software tool.The problem objective is considered in terms of cost,but the energy system is constrained to meet the power demand reliably.Process simulations were performed to determine the optimum sizing,performance and monetary cost of the power system,using long-term meteorological datasets for a case study site with defined longitude(31◦25E)and latitude(30◦06N).From the observed results,the total net present cost(NPC)of the proposed system is$28,187.Indeed,these outcomes can provide profound economic,technical,and ecological benefits to cellular operators.It also ensures a sizeable reduction in greenhouse gas that supports sustainable green wireless network(WN)deployment in remote areas.
文摘The development of the capabilities of computational tools has created up new possibilities for the effective use of a number of classical mathematical methods and algorithms for solving many important problems in the power engineering. In particular, a set of algorithms are developed to optimize the modes of electric power systems based on genetic algorithms. At the same time, the issues of taking into account functional constraints in solving such problems by genetic algorithms need to be improved. In accordance with it in this article the problems of taking into account of different constraints in optimization of modes of power systems using genetic algorithms are considered. The algorithm of optimization by genetic algorithm taking into account of functional constraints in forms of equality and inequality by penalty functions is proposed. The results of research of proposed algorithm’s efficiency in example of optimization of mode of power system with 8 buses, 4 thermal power plants and 3 transmission lines with controlled power flow are presented.
文摘In this paper a new market based analytical model is proposed for optimal placement of Wind Turbines (WTs) in power systems. In addition to wind turbines, thermal units (THUs) and Pumped Storage Hydro Power Plants (PSHPPs) owners participate in power market. Objective function is defined as participants’ social welfare achieved from power pool and ancillary markets in yearly horizon. Wind turbines have been modeled by probability-generation tree scenarios based on statistical information. We concentrate on investment profits of WTs numbers and its generation capacity beside to PSHPPs and THUs power plants in power systems due to increase in high flexible tools for Independent system operator into the planning and operation planning time interval. For effectiveness evaluation of proposed model, simulation studies are applied on 14-Bus IEEE test power system.
文摘RES （renewable energy sources）, such as wind and photovoltaic power plants, suffer from their stochastic nature that is why their behavior on market is very delicate. In order to diversify risk, a concept of VPP （virtual power plant） has been developed. The VPP is composed of several RES, from which at least one of them is fully controllable. Because the production of noncontrollable RES can not be forecasted perfectly, therefore an optimal dispatch schedule within VPP is needed. To address this problem, an APSO （accelerated particle swarm optimization） is used to solve the constrained optimal dispatch problem within VPP. The experimental results show that the proposed optimization method provides high quality solutions while meeting constraints.
文摘The paper presents results from a study of a series-connected single-phase APF （active power filter） with a control system based on hysteresis control, both with and without limitation of the maximum switching frequency. The general purpose of the series APF is to eliminate the low order harmonics of the source （grid） voltage. The filter operation at limited and unlimited maximum switching frequency is explained and it is described using building blocks and time diagrams illustrating the tracking down of the reference curve. Waveforms from the computer simulation and waveforms from the experimental tests of the filter are presented also for the two situations. Operations at limited and unlimited maximum switching frequency are compared regarding the quality of the voltage across the load, the complexity of the implementation of the control system, and the electromagnetic compatibility. The investigation proved capability of the series APF to achieve its general purpose using the hysteresis control methods studied （limited and unlimited switching frequency）.
基金the Natural Science Foundation of Hebei Province,China(Grant No.E2022502052)Fundamental Research Funds for the Central Universities,China(Grant No.2022MS081)Fundamental Research Funds for the Central Universities,China(Grant No.2023MS121).
文摘This study explores the influence of rotor blade angle on stall inception in an axial fan by means of numerical simulations grounded in the Reynolds-Averaged Navier-Stokes(RANS)equations and the Realizable k-εturbulence model.By analyzing the temporal behavior of the outlet static pressure,along with the propagation velocity of stall inception,the research identifies distinct patterns in the development of stall.The results reveal that stall inception originates in the second rotor impeller.At a blade angle of 27°,the stall inception follows a modal wave pattern,while in all other cases,it assumes the form of spike-type stall.The flow field associated with spike stall inception demonstrates a relatively uniform gradient in the radial direction,whereas the modal wave stall case displays a distinctive“L”-shaped propagation feature.At blade angles of multiple stall inceptions are observed.-9°and-18°,These phenomena initiate at the blade’s leading edge,propagate along both axial and radial directions,and transition dynamically between single and multiple inception states.
文摘Enhancing the fermentation efficiency of waste in waste warehouses is pivotal for accelerating the pyrolysis process and minimizing harmful gas emissions.This study proposes an integrated approach,combining hot air injection with dual atomizing nozzles,for the thermal treatment of waste piles.Numerical simulations are employed to investigate the influence of various parameters,namely,nozzle height,nozzle tilt angle,inlet air velocity and air temperature,on the droplet diffusion process,spread area,droplet temperature,and droplet size distribution.The results show that reducing the nozzle height increases the temperature of droplets upon their deposition on the waste pile.Specifically,when the nozzle height is lowered to 1.5 m,the temperature of the droplets reaching the waste pile is 1℃higher than when the nozzle height is set at 2 m.Furthermore,an increase in the nozzle tilt angle expands the overlapping heating area.For instance,when the nozzle angle is increased from 15°to 30°,the overlapping spread area expands by 3.21 m2.Additionally,increasing the inlet air velocity enhances the droplet diffusion range.At an air velocity of 2 m/s,the droplet diffusion range grows to 14.4 m,representing a 6.7%increase compared to the nowind condition.While the average droplet diameter decreases to 1.53 mm,the droplet temperature decreases by 1℃.Moreover,the droplet temperature is found to become smaller as the ambient temperature inside the waste warehouse declines.Specifically,a 5℃reduction in the ambient temperature results in a 1℃decrease in the average temperature of the atomized droplets.The study concludes that a nozzle height of 1.5 m and a nozzle tilt angle of 30°effectively meet practical heating requirements.
基金the state assign-ment of Ministry of Science and Higher Education of the Russian Federation(theme No 123102000012-2“Compre-hensive study of aerodynamic characteristics of plasma systems of thermochemical fuel preparation”,agreement No 075-03-2023-028/1 of 05.10.2023).
文摘Modern electric traction networks(ETN)are equipped with automated systems for commercial accounting of power consumption(ASCAPC),which allows solving properly the problems of enhancing the energy efficiency of transportation processes.Energy efficiency of ETNs is defined as the amount of power losses in ETN components:overhead catenary systems and traction transformers.Due to the instability of traction loads and changes in their location in space,the electric traction network is different from the general network.It is necessary to develop an approach for loss analysis in traction networks and in transformers of traction substations.To solve this prob-lem,a balance-based technique for power loss calculation in traction networks based on ASCAPC data is proposed.First,the balance-based technique presented here breaks down the power consumption of the train by source.Then,calculates technical power losses in 25 and 225 kV traction networks as well as in traction transformers.Last,the technique is implemented in the form of an algorithm tested on real-life data and it is ready for practical use.
基金supported by the National Natural Science Foundation of China(Grants No.42177431 and No.U20A2086)the Beijing Natural Science Foundation(International Scientists Project,Grant No.IS24033)+3 种基金the joint research project between UniMAP and TIIAME NRU(Grant No.INTERES 9008-00064)the series training courses(Belt&Road Talent Exchange Program,Grant No.DL2021108001L)for academic writing guidance that conducted by Prof.Harold J.Annegarnthe support from China Scholarship CouncilTYSP program to the international students and scholars。
文摘One of the solutions to the global warming risk and other climate issues is to concentrate on research and development of utilizing biomass as a fossil fuel alternative.The current estimate of cotton residue waste in the world is about 50 million tons.This massive volume of biomass waste should be turned into clean energy to avert burning the stalks in open fields after cotton harvesting.Therefore,harmful emissions such as CO_(2) will be reduced.This study aims to investigate the published literature to comprehend the bioenergy production from the thermal treatment of cotton stalks,including combustion,pyrolysis,carbonization,torrefaction,liquefaction,and gasification.Furthermore,the future outlook,utilization,and prospective challenges of agricultural biomass for biofuel production are discussed.According to the literature,biochar and bio-oil derived from cotton stalks have high heating values of about 27.5 and 37.2 MJ·kg~(–1),respectively.These values are double those of cotton stalk raw materials,which make it a good candidate for bioenergy production.This article offers valuable insight into cotton stalk utilization via thermochemical treatment and provides a solid reference for researchers,policymakers,and other stakeholders in this field.
文摘The target of this paper is the performance-based diagnostics of a gas turbine for the automated early detection of components malfunctions. The paper proposes a new combination of multiple methodologies for the performance-based diagnostics of single and multiple failures on a two-spool engine. The aim of this technique is to combine the strength of each methodology and provide a high success rate for single and multiple failures with the presence of measurement malfunctions. A combination of KF(Kalman Filter), ANN(Artificial Neural Network) and FL(Fuzzy Logic) is used in this research in order to improve the success rate, to increase the flexibility and the number of failures detected and to combine the strength of multiple methods to have a more robust solution. The Kalman filter has in his strength the measurement noise treatment, the artificial neural network the simulation and prediction of reference and deteriorated performance profile and the fuzzy logic the categorization flexibility, which is used to quantify and classify the failures. In the area of GT(Gas Turbine) diagnostics, the multiple failures in combination with measurement issues and the utilization of multiple methods for a 2-spool industrial gas turbine engine has not been investigated extensively.This paper reports the key contribution of each component of the methodology and brief the results in the quantification and classification success rate. The methodology is tested for constant deterioration and increasing noise and for random deterioration. For the random deterioration and nominal noise of 0.4%, in particular, the quantification success rate is above 92.0%, while the classification success rate is above 95.1%. Moreover, the speed of the data processing(1.7 s/sample)proves the suitability of this methodology for online diagnostics.
基金supported by the National Natural Science Foundation of China (Nos. 90916023 and 51176075)
文摘The aerodynamic design of a rigid-flexible coupling profile is the decisive factor for the flow-field quality of a supersonic free jet wind tunnel nozzle, and its mechanic dynamic features are the key for engineering implementation of continuous Mach number regulations. To fulfill the requirements of a free jet inlet/engine compatibility test within a wide simulation envelop, both uniform flow-fields of continuous acceleration and deceleration are necessary. In this paper, the aerodynamic design methods of an expansion wall and machinery implementation plan for the halfflexible single jack nozzle were researched. The profile control in nozzle flexible plate design was studied with a rigid-flexible coupling method. Design and calculations were performed with the help of numerical simulation. The technique of axial free stretching of the flexible plate was used to improve the matching performance between the designed elasticity profile and the theoretical one, and the rigid-flexible coupling structure was calibrated by wind tunnel tests. Results indicate that the flexible plate aerodynamic design method used here is effective and feasible. Via rigidflexible coupling design, the flexible plate agrees with the rigid body very well, and continuous Mach number changes can be achieved during the tests. The nozzle’s exit flow-field uniformity meets the requirements of China Military Standard(GJB).
文摘The heat transfer coefficient in a multidimensional heat conduction problem is obtained from the solution of the inverse heat conduction problem based on the thermographic temperature measurement. The modified one-dimensional correction method （MODCM）, along with the finite volume method, is employed for both two- and three-dimensional inverse problems. A series of numerical experiments are conducted in order to verify the effectiveness of the method. In addition, the effect of the temperature measurement error, the ending criterion of the iteration, etc. on the result of the inverse problem is investigated. It is proved that the method is a simple, stable and accurate one that can solve successfully the inverse heat conduction problem.
基金Project supported by the National Natural Sciences Foundation of China(No.50576037)Natural Science Foundation of Jiangsu Province(No.BK2006198)
文摘In order to investigate the feasibility of sequential removal NO and SO2 using non-thermal plasma and adsorbent simultaneously, the removal of NO and SO2 from dry gas stream （NO/SO2/N2/O2） with very little O2 using non-thermal plasma was investigated using a coaxial dielectric barrier discharge. Comparative experiments were carried out in the dry gas stream with and without Ar respectively at O2 concentration of 0.1%. The results showed that NO could be removed remarkably and it would be enhanced in the presence of Ar in the dry gas stream. It seems that SO2 could not be removed unless there is Ar in the dry gas stream. The mechanism of removal of NO and SO2 in the dry gas stream was discussed.
基金Funded by the National Science and Technology Support Project of China (No. 2006BAA03B02-03)
文摘A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is based on the assumptions that the difference of temperature along the longitudinal axis of the boiler drum is negligible with changes only in the radial direction and the circumferential direction, and that the outer surface of drum is thermaUy insulated. Combining this model with the control-volume method provides temperatures at different points on a cross-section of the drum. With the temperature data, the stresses and the life expectancy of the boiler drum are derived according to the ASME code. Applying this method to the cold start-up process of a 300 MW boiler demonstrated the absence of errors caused by the boundary condition assumptions on the inner surface of the drum and testified that the method is an applicable technique for the online stress monitoring and fatigue life analysis of boiler drums.
