Until now, it has been difficult to obtain on-line three-dimensional (3-D) temperature distribution information which can reflect the overall combustion condition in the furnace of a coal-fired power plant boiler. A c...Until now, it has been difficult to obtain on-line three-dimensional (3-D) temperature distribution information which can reflect the overall combustion condition in the furnace of a coal-fired power plant boiler. A combustion monitoring system is introduced which can solve the problem efficiently. Through this system, the 3-D temperature distribution in a coal-fired boiler furnace can be obtained using a novel flame image processing technique. Briefly, we first outline the visualization principle. Then, the hardware and software design of the system in a 300 MW twin-furnace coal-fired boiler are introduced in detail. The visualization of the 3-D temperature distribution in the twin-furnace boiler is realized with an industrial computer and the Distributed Control System (DCS) of the boiler. The practical operation of the system shows that it can provide valuable combustion information of a furnace and is useful for the combustion diagnosis and adjustment in coal-fired power plants.展开更多
Microstructure of reaction sintering of ZnAl2O4 at 1500℃ by hot-pressing(HP) and pulse electric current was investigated. The results indicated that the existed cracks in sintered body were caused by structure mismat...Microstructure of reaction sintering of ZnAl2O4 at 1500℃ by hot-pressing(HP) and pulse electric current was investigated. The results indicated that the existed cracks in sintered body were caused by structure mismatch. It is the evidence that periodical temperature field existed during pulse electric current sintering of nonconductive materials. The distance between high temperature areas was related to die diameter.展开更多
In this paper, the radial temperature distributions of the blown CO2 arcs in a model gas circuit breaker were investigated by optical emission spectroscopy methods. The CO2 flows with different flow rates(50, 100 and ...In this paper, the radial temperature distributions of the blown CO2 arcs in a model gas circuit breaker were investigated by optical emission spectroscopy methods. The CO2 flows with different flow rates(50, 100 and 150 1 min^-1) were created to axially blow the arcs burning in a polymethyl methacrylate(PMMA) nozzle. Discharges with different arc currents(200 and 400A) were conducted in the experiment. The absolute intensity method was applied for a carbon ionic line of 657.8 nm to obtain the radial temperature profiles of the arc columns at a cross-section 1 mm above the nozzle. The calibration for the intensity of the CⅡ 657.8 nm line was achieved by the Fowler–Milne method with the help of an oxygen atomic line of 777.2 nm.The highest temperature obtained in the arc center was up to 19 900 K when the arc current was 400 A and the CO2 flow rate was 50 1 min^-1, while the lowest temperature in the arc center was about 15 900 K when the arc current was 200 A and the CO2 flow rate was 150 1min^-1. The results indicate that as the arc current increases, the temperature in the arc center would also increase apparently, and a larger gas flow rate would lead to a lower central temperature in general. It can also be found that the influence of the CO2 flow rate on the arc temperature was much less than that of the arc current under the present experimental conditions. In addition,higher temperature in the arc center would cause a sharper temperature decrease from the central region towards the edge.展开更多
It is known from the New Energy and Industry Technology Development Organization (NEDO) roam map Japan, 2017 that the polymer electrolyte fuel cell (PEFC) power generation system is required to operate at 100°C f...It is known from the New Energy and Industry Technology Development Organization (NEDO) roam map Japan, 2017 that the polymer electrolyte fuel cell (PEFC) power generation system is required to operate at 100°C for application of mobility usage from 2020 to 2025. This study aims to clarify the effect of separator thickness on the distribution of the temperature of reaction surface (T<sub>react</sub>) at the initial temperature of cell (T<sub>ini</sub>) with flow rate, relative humidity (RH) of supply gases as well as RH of air surrounding cell of PEFC. The distribution of T<sub>react</sub> is estimated by means of the heat transfer model considering the H<sub>2</sub>O vapor transfer proposed by the authors. The relationship between the standard deviation of T<sub>react</sub>-T<sub>ini</sub> and total voltage obtained in the experiment is also investigated. We can know the effect of the flow rate of supply gas as well as RH of air surrounding cell of PEFC on the distribution of T<sub>react</sub>-T<sub>ini</sub> is not significant. It is observed the wider distribution of T<sub>react</sub>-T<sub>ini</sub> provides the reduction in power generation performance irrespective of separator thickness. In the case of separator thickness of 1.0 mm, the standard deviation of T<sub>react</sub>-T<sub>ini</sub> has smaller distribution range and the total voltage shows a larger variation compared to the other cases.展开更多
This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and position...This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and positions,while the followers can measure the relative bearings or(angular and linear)velocities in their unknown local coordinate frames.For the orientation estimation,the local relative bearings are used to obtain the relative orientations among the agents,based on which a distributed orientation estimation algorithm is proposed for each follower to estimate its orientation.For the position estimation,the local relative bearings are used to obtain the position constraints among the agents,and a distributed position estimation algorithm is proposed for each follower to estimate its position by solving its position constraints.Both the orientation and position estimation errors converge to zero asymptotically.A simulation example is given to verify the theoretical results.展开更多
A physics-based analytical expression that predicts the charge,electrical field and potential distributions along the gated region of the GaN HEMT channel has been developed.Unlike the gradual channel approximation(GC...A physics-based analytical expression that predicts the charge,electrical field and potential distributions along the gated region of the GaN HEMT channel has been developed.Unlike the gradual channel approximation(GCA),the proposed model considers the non-uniform variation of the concentration under the gated region as a function of terminal applied volt-ages.In addition,the model can capture the influence of mobility and channel temperature on the charge distribution trend.The comparison with the hydrodynamic(HD)numerical simulation showed a high agreement of the proposed model with numerical data for different bias conditions considering the self-heating and quantization of the electron concentration.The ana-lytical nature of the model allows us to reduce the computational and time cost of the simulation.Also,it can be used as a core expression to develop a complete physics-based transistorⅣmodel without GCA limitation.展开更多
In order to research the distribution of thermal field of low temperature discharge from LNG in the ocean, further to formulate reasonable wastewater marine disposal scheme and provide scientific support to the protec...In order to research the distribution of thermal field of low temperature discharge from LNG in the ocean, further to formulate reasonable wastewater marine disposal scheme and provide scientific support to the protection of ocean environment, a two-dimensional hydrodynamic model was used to simulate the tide current field in the radial sand ridge group of shallow sea area of Jiangsu maritime space. This model was based on the tide current characteristics near the LNG project and the seasonal design of the typical hydrological conditions in different seasons. This model was used as the hydrodynamic condition that simulated the transport and diffusion for the heat quantity in the change of time and spatial distribution. Considering the comprehensive heat radiation coefficient of water surface, the 2-D water temperature model was established to predict the spatial distribution and temporal variation of the temperature field in the receiving waters. Finally, results showed that the low temperature drainage less affected in the ocean water environment.展开更多
In this study, the solar thermochemical reactor performance for CO_2 utilization into synthesis gas(H_2+ CO) based on CH_4 reforming process was investigated in the context of carbon capture and utilization(CCU) techn...In this study, the solar thermochemical reactor performance for CO_2 utilization into synthesis gas(H_2+ CO) based on CH_4 reforming process was investigated in the context of carbon capture and utilization(CCU) technologies. The P1 radiation heat transfer model is adopted to establish the heat and mass transfer model coupled with thermochemical reaction kinetics. The reactor thermal behavior with direct heat transfer between gaseous reactant and products evolution and the effects of different structural parameters were evaluated. It was found that the reactor has the potential to utilize by ～60% of CO_2 captured with 40% of CH_4 co-fed into syngas(72.9% of H_2 and 27.1% of CO) at 741.31 k W/mof incident radiation heat flux. However, the solar irradiance heat flux and temperature distribution were found to significantly affect the reactant species conversion efficiency and syngas production. The chemical reaction is mainly driven by the thermal energy and higher species conversion into syngas was observed when the temperature distribution at the inner cavity of the reactor was more uniform. Designed a solar thermochemical reactor able to volumetric store concentrated irradiance could highly improve CCU technologies for producing energy-rich chemicals. Besides, the mixture gas inlet velocity, operating pressure and CO_2/CH_4 feeding ratio were crucial to determining the efficiency of CO_2 utilization to solar fuels. Catalytic CO_2-reforming of CH_4 to chemical energy is a promising strategy for an efficient utilization of CO_2 as a renewable carbon source.展开更多
基金Project 50636010 supported by the National Natural Science Foundation of China
文摘Until now, it has been difficult to obtain on-line three-dimensional (3-D) temperature distribution information which can reflect the overall combustion condition in the furnace of a coal-fired power plant boiler. A combustion monitoring system is introduced which can solve the problem efficiently. Through this system, the 3-D temperature distribution in a coal-fired boiler furnace can be obtained using a novel flame image processing technique. Briefly, we first outline the visualization principle. Then, the hardware and software design of the system in a 300 MW twin-furnace coal-fired boiler are introduced in detail. The visualization of the 3-D temperature distribution in the twin-furnace boiler is realized with an industrial computer and the Distributed Control System (DCS) of the boiler. The practical operation of the system shows that it can provide valuable combustion information of a furnace and is useful for the combustion diagnosis and adjustment in coal-fired power plants.
基金This work was supported by the National Natural Science Foundation of China under grant No.50232020 and 50220160657.
文摘Microstructure of reaction sintering of ZnAl2O4 at 1500℃ by hot-pressing(HP) and pulse electric current was investigated. The results indicated that the existed cracks in sintered body were caused by structure mismatch. It is the evidence that periodical temperature field existed during pulse electric current sintering of nonconductive materials. The distance between high temperature areas was related to die diameter.
基金supported by National Natural Science Foundation of China (Nos. 51577145, 51707144 and 51877165)the Key Research and Development Program of Shaanxi Province (No. 2018ZDXM-GY-112)the State Key Laboratory of Electrical Insulation and Power Equipment (No. EIPE19302)
文摘In this paper, the radial temperature distributions of the blown CO2 arcs in a model gas circuit breaker were investigated by optical emission spectroscopy methods. The CO2 flows with different flow rates(50, 100 and 150 1 min^-1) were created to axially blow the arcs burning in a polymethyl methacrylate(PMMA) nozzle. Discharges with different arc currents(200 and 400A) were conducted in the experiment. The absolute intensity method was applied for a carbon ionic line of 657.8 nm to obtain the radial temperature profiles of the arc columns at a cross-section 1 mm above the nozzle. The calibration for the intensity of the CⅡ 657.8 nm line was achieved by the Fowler–Milne method with the help of an oxygen atomic line of 777.2 nm.The highest temperature obtained in the arc center was up to 19 900 K when the arc current was 400 A and the CO2 flow rate was 50 1 min^-1, while the lowest temperature in the arc center was about 15 900 K when the arc current was 200 A and the CO2 flow rate was 150 1min^-1. The results indicate that as the arc current increases, the temperature in the arc center would also increase apparently, and a larger gas flow rate would lead to a lower central temperature in general. It can also be found that the influence of the CO2 flow rate on the arc temperature was much less than that of the arc current under the present experimental conditions. In addition,higher temperature in the arc center would cause a sharper temperature decrease from the central region towards the edge.
文摘It is known from the New Energy and Industry Technology Development Organization (NEDO) roam map Japan, 2017 that the polymer electrolyte fuel cell (PEFC) power generation system is required to operate at 100°C for application of mobility usage from 2020 to 2025. This study aims to clarify the effect of separator thickness on the distribution of the temperature of reaction surface (T<sub>react</sub>) at the initial temperature of cell (T<sub>ini</sub>) with flow rate, relative humidity (RH) of supply gases as well as RH of air surrounding cell of PEFC. The distribution of T<sub>react</sub> is estimated by means of the heat transfer model considering the H<sub>2</sub>O vapor transfer proposed by the authors. The relationship between the standard deviation of T<sub>react</sub>-T<sub>ini</sub> and total voltage obtained in the experiment is also investigated. We can know the effect of the flow rate of supply gas as well as RH of air surrounding cell of PEFC on the distribution of T<sub>react</sub>-T<sub>ini</sub> is not significant. It is observed the wider distribution of T<sub>react</sub>-T<sub>ini</sub> provides the reduction in power generation performance irrespective of separator thickness. In the case of separator thickness of 1.0 mm, the standard deviation of T<sub>react</sub>-T<sub>ini</sub> has smaller distribution range and the total voltage shows a larger variation compared to the other cases.
基金supported by Nanyang Technological University,Singapore under the Wallenberg-NTU Presidential Postdoctoral Fellowship and the Natural Science Foundation in Heilongjiang Province,China(YQ2022F003).
文摘This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and positions,while the followers can measure the relative bearings or(angular and linear)velocities in their unknown local coordinate frames.For the orientation estimation,the local relative bearings are used to obtain the relative orientations among the agents,based on which a distributed orientation estimation algorithm is proposed for each follower to estimate its orientation.For the position estimation,the local relative bearings are used to obtain the position constraints among the agents,and a distributed position estimation algorithm is proposed for each follower to estimate its position by solving its position constraints.Both the orientation and position estimation errors converge to zero asymptotically.A simulation example is given to verify the theoretical results.
基金This work was supported by the National Natural Science Foundation of China(NSFC)under Grant 61774141.
文摘A physics-based analytical expression that predicts the charge,electrical field and potential distributions along the gated region of the GaN HEMT channel has been developed.Unlike the gradual channel approximation(GCA),the proposed model considers the non-uniform variation of the concentration under the gated region as a function of terminal applied volt-ages.In addition,the model can capture the influence of mobility and channel temperature on the charge distribution trend.The comparison with the hydrodynamic(HD)numerical simulation showed a high agreement of the proposed model with numerical data for different bias conditions considering the self-heating and quantization of the electron concentration.The ana-lytical nature of the model allows us to reduce the computational and time cost of the simulation.Also,it can be used as a core expression to develop a complete physics-based transistorⅣmodel without GCA limitation.
文摘In order to research the distribution of thermal field of low temperature discharge from LNG in the ocean, further to formulate reasonable wastewater marine disposal scheme and provide scientific support to the protection of ocean environment, a two-dimensional hydrodynamic model was used to simulate the tide current field in the radial sand ridge group of shallow sea area of Jiangsu maritime space. This model was based on the tide current characteristics near the LNG project and the seasonal design of the typical hydrological conditions in different seasons. This model was used as the hydrodynamic condition that simulated the transport and diffusion for the heat quantity in the change of time and spatial distribution. Considering the comprehensive heat radiation coefficient of water surface, the 2-D water temperature model was established to predict the spatial distribution and temporal variation of the temperature field in the receiving waters. Finally, results showed that the low temperature drainage less affected in the ocean water environment.
基金supported by the National Natural Science Foundation of China (No. 51522601)Chang Jiang Young Scholars Program of China (Q2016186)the Fok Ying Tong Education Foundation of China (No. 141055)
文摘In this study, the solar thermochemical reactor performance for CO_2 utilization into synthesis gas(H_2+ CO) based on CH_4 reforming process was investigated in the context of carbon capture and utilization(CCU) technologies. The P1 radiation heat transfer model is adopted to establish the heat and mass transfer model coupled with thermochemical reaction kinetics. The reactor thermal behavior with direct heat transfer between gaseous reactant and products evolution and the effects of different structural parameters were evaluated. It was found that the reactor has the potential to utilize by ～60% of CO_2 captured with 40% of CH_4 co-fed into syngas(72.9% of H_2 and 27.1% of CO) at 741.31 k W/mof incident radiation heat flux. However, the solar irradiance heat flux and temperature distribution were found to significantly affect the reactant species conversion efficiency and syngas production. The chemical reaction is mainly driven by the thermal energy and higher species conversion into syngas was observed when the temperature distribution at the inner cavity of the reactor was more uniform. Designed a solar thermochemical reactor able to volumetric store concentrated irradiance could highly improve CCU technologies for producing energy-rich chemicals. Besides, the mixture gas inlet velocity, operating pressure and CO_2/CH_4 feeding ratio were crucial to determining the efficiency of CO_2 utilization to solar fuels. Catalytic CO_2-reforming of CH_4 to chemical energy is a promising strategy for an efficient utilization of CO_2 as a renewable carbon source.
