Due to low cost,high capacity,and high energy density,lithium–sulfur(Li–S)batteries have attracted much attention;however,their cycling performance was largely limited by the poor redox kinetics and low sulfur utili...Due to low cost,high capacity,and high energy density,lithium–sulfur(Li–S)batteries have attracted much attention;however,their cycling performance was largely limited by the poor redox kinetics and low sulfur utilization.Herein,predicted by density functional theory calculations,single‐atomic Co‐B2N2 site‐imbedded boron and nitrogen co‐doped carbon nanotubes(SA‐Co/BNC)were designed to accomplish high sulfur loading,fast kinetic,and long service period Li–S batteries.Experiments proved that Co‐B2N2 atomic sites can effectively catalyze lithium polysulfide conversion.Therefore,the electrodes delivered a specific capacity of 1106 mAh g−1 at 0.2 C after 100 cycles and exhibited an outstanding cycle performance over 1000 cycles at 1 C with a decay rate of 0.032%per cycle.Our study offers a new strategy to couple the combined effect of nanocarriers and single‐atomic catalysts in novel coordination environments for high‐performance Li–S batteries.展开更多
As a knowledge-intensive and promising strategic emerging industry, the biomedical industry has high entry thresholds, large R&D investment, long cycle, high risk and high return. In all technical fields, the biom...As a knowledge-intensive and promising strategic emerging industry, the biomedical industry has high entry thresholds, large R&D investment, long cycle, high risk and high return. In all technical fields, the biomedical industry has the highest dependence on intellectual property rights, and the protection of pharmaceutical intellectual property rights by domestic and foreign biomedical enterprises also runs through the whole process of drug research and development. Extending the patent protection period of drugs as well as forming and strengthening patent fortresses requires a patent network that surrounds drugs to maximize the value of intellectual property protection, which is also the focus of every pharmaceutical company with patent rights. By analyzing the patent portfolio of Clovis Oncology Company in the United States on Rucaparib and the patent portfolio of other companies or applicants on Rucaparib, we can have a clearer understanding of the strategy of extending the patent protection period of a new drug product.展开更多
A 40 Gb/s high speed optical transmission system is designed, and the different dispersion compensation schemes are adopted to realize the transmission of the optical duo-binary (ODB) signals over 120 km optical fiber...A 40 Gb/s high speed optical transmission system is designed, and the different dispersion compensation schemes are adopted to realize the transmission of the optical duo-binary (ODB) signals over 120 km optical fiber. Optical duo-binary signals are generated by using a precoder, two low- pass filters (LPF) and one mach-zehnder modulator (MZM). Through combination of dispersion compensation fiber (DCF) and single mode fiber (SMF) in the transmission link, four different dispersion compensation schemes (pre-compensation, post-compensation and hybrid compensation (pre+ post) and hybrid compensation (post+ pre)) were compared. Analyzing Q factor, BER, eye diagrams and receiver sensitivity in several dispersion compensation schemes, the simulation results are: the cut-off frequency of LPF affects the transmission performance, and the hybrid compensation (post+ pre) scheme is the optimal dispersion compensation method.展开更多
In this article, the peak to average power ratio (PAPR) performance of 8 quadrature amplitude modulation-orthogonal frequency division multiplexing (8QAM-OFDM) optical signals has been researched in broadband optical ...In this article, the peak to average power ratio (PAPR) performance of 8 quadrature amplitude modulation-orthogonal frequency division multiplexing (8QAM-OFDM) optical signals has been researched in broadband optical access system. The complementary cumulative distribution functions (CCDFs) are analyzed of two different 8QAM-OFDMsignals with 16, 32, 64, 128, 256, 512 sub- carriers by simulation. The simulation results show that, with the increase of the number of subcarrier, the PAPR value becomes higher. When the numbers of subcarrier are16 and 512, the PAPR of 8QAM-OFDM optical signals are smaller than 5.2 dB and 5.3 dB respectively. Hence, the number of sub-carriers should be chosen according to practical application.展开更多
Free Space Optical (FSO) communication is one of the most promising access methods. But, the different weather conditions will affect the transceiver performance. In this paper, we build a FSO communication system wit...Free Space Optical (FSO) communication is one of the most promising access methods. But, the different weather conditions will affect the transceiver performance. In this paper, we build a FSO communication system with 16-ary phase shift key-orthogonal frequency division multiplexing (16PSK-OFDM) downstream signals. We analyze the transmission performance of 16PSK-OFDM optical signals under five different weather conditions (sunny, light rain, moderate rain, snow, and fog). The optical spectral diagrams, constellation diagrams, and bit error rate (BER) of the received signals are simulation measured and analyzed. The results show that the constellation diagram under sunny condition is clear, and the value of BER is about 10?4.2 after 16PSK-OFDM optical signals pass through 500 m FSO link. Note that, the constellation points are dispersed under the other weather conditions.展开更多
In this paper, the downstream transmission performance of two types of 8QAM-OFDM optical signals in broadband optical access system has been analyzed. After modulation and coding, two types of 10 Gbit/s 8QAM-OFDM opti...In this paper, the downstream transmission performance of two types of 8QAM-OFDM optical signals in broadband optical access system has been analyzed. After modulation and coding, two types of 10 Gbit/s 8QAM-OFDM optical access signals are downstream transmitted over 1 km, 10 km, 20 km and 40 km single mode fibers (SMFs) and received successfully. Different transmission distances impact on the bit error rate (BER) of the received signal is analyzed by simulation, while the signal to noise ratio (SNR) is 20 dB. The results show that, while the transmission distance is shorter than 10 km, the BER values of two types of 8QAM-OFDM optical signals are smaller than 10?10. As the above optical access signals are transmitted over 40 km SMF, the BER value of the first type of 8QAM-OFDM signals is bigger than 10?6, and the BER of the other type of 8QAM-OFDM signals is smaller than 10?6.展开更多
In this paper, the transceiver performance of optical 64QAM-OFDM signals with different sub-car- riers is studied. Firstly, we build a 40Gbit/s optical coherent 64QAM-OFDM transmission system. 64QAM-OFDM optical signa...In this paper, the transceiver performance of optical 64QAM-OFDM signals with different sub-car- riers is studied. Firstly, we build a 40Gbit/s optical coherent 64QAM-OFDM transmission system. 64QAM-OFDM optical signals with 16, 32, 64, 64, 128, 256 and 512 sub-carriers are transmitted over 100 km single mode fiber (SMF). Then, the optical spectrum diagrams before and after transmission, the bit error rate (BER) and constellation diagrams of received signals were compared. The simulation results show that, with the number of sub-carriers increasing, the value of PAPR will gradually increase and the quality of the received optical signals will deteriorate. Moreover, with the number of sub-carriers increasing, the computational complexity will increase when digital signal processing (DSP) is used. Therefore, we should choose the optimal number of sub-carriers, and the PAPR influence and BER are also considered for achieving effective transmission.展开更多
Coordinated signal processing can obtain a huge transmission gain for Fog Radio Access Networks(F-RANs).However,integrating into large scale,it will lead to high computation complexity in channel estimation and spectr...Coordinated signal processing can obtain a huge transmission gain for Fog Radio Access Networks(F-RANs).However,integrating into large scale,it will lead to high computation complexity in channel estimation and spectral efficiency loss in transmission performance.Thus,a joint cluster formation and channel estimation scheme is proposed in this paper.Considering research remote radio heads(RRHs)centred serving scheme,a coalition game is formulated in order to maximize the spectral efficiency of cooperative RRHs under the conditions of balancing the data rate and the cost of channel estimation.As the cost influences to the necessary consumption of training length and estimation error.Particularly,an iterative semi-blind channel estimation and symbol detection approach is designed by expectation maximization algorithm,where the channel estimation process is initialized by subspace method with lower pilot length.Finally,the simulation results show that a stable cluster formation is established by our proposed coalition game method and it outperforms compared with full coordinated schemes.展开更多
A novel method was reported to measure the remnant magnetic field in Lorentz mode in a FEI Tecnai F20 transmission electron microscope equipped with a Lorentz lens. The movement of the circle Bloch line of the cross-t...A novel method was reported to measure the remnant magnetic field in Lorentz mode in a FEI Tecnai F20 transmission electron microscope equipped with a Lorentz lens. The movement of the circle Bloch line of the cross-tie wall in Permalloy is used to measure the remnant magnetic field by tilting the specimen and adjusting the objective lens current. The remnant magnetic field is estimated to be about 17 Oe, in a direction opposite to that of the objective lens magnetic field. The remnant magnetic field can be compensated by adjusting the value of the objective lens current.展开更多
Speech resampling is a typical tempering behavior,which is often integrated into various speech forgeries,such as splicing,electronic disguising,quality faking and so on.By analyzing the principle of resampling,we fou...Speech resampling is a typical tempering behavior,which is often integrated into various speech forgeries,such as splicing,electronic disguising,quality faking and so on.By analyzing the principle of resampling,we found that,compared with natural speech,the inconsistency between the bandwidth of the resampled speech and its sampling ratio will be caused because the interpolation process in resampling is imperfect.Based on our observation,a new resampling detection algorithm based on the inconsistency of band energy is proposed.First,according to the sampling ratio of the suspected speech,a band-pass Butterworth filter is designed to filter out the residual signal.Then,the logarithmic ratio of band energy is calculated by the suspected speech and the filtered speech.Finally,with the logarithmic ratio,the resampled and original speech can be discriminated.The experimental results show that the proposed algorithm can effectively detect the resampling behavior under various conditions and is robust to MP3 compression.展开更多
Primary and secondary growth of the tree stem are responsible for corresponding increases in trunk height and diameter.However,our molecular understanding of the biological processes that underlie these two types of g...Primary and secondary growth of the tree stem are responsible for corresponding increases in trunk height and diameter.However,our molecular understanding of the biological processes that underlie these two types of growth is incomplete.In this study,we used single-cell RNA sequencing and spatial transcriptome sequencing to reveal the transcriptional landscapes of primary and secondary growth tissues in the Populus stem.Comparison between the cell atlas and differentiation trajectory of primary and secondary growth revealed different regulatory networks involved in cell differentiation from cambium to xylem precursors and phloem precursors.These regulatory networks may be controlled by auxin accumulation and distribution.Analysis of cell differentiation trajectories suggested that vessel and fiber development followed a sequential pattern of progressive transcriptional regulation.This research provides new insights into the processes of cell identity and differentiation that occur throughout primary and secondary growth of tree stems,increasing our understanding of the cellular differentiation dynamics that occur during stemgrowth in trees.展开更多
In conventional photovoltaic(PV) systems, a large portion of solar energy is dissipated as waste heat since the generating efficiency is usually less than 30%. As the dissipated heat can be recovered for various appli...In conventional photovoltaic(PV) systems, a large portion of solar energy is dissipated as waste heat since the generating efficiency is usually less than 30%. As the dissipated heat can be recovered for various applications, the wasted heat recovery concentrator PV/thermal(WHR CPVT) hybrid systems have been developed. They can provide both electricity and usable heat by combining thermal systems with concentrator PV(CPV) module, which dramatically improves the overall conversion efficiency of solar energy.This paper systematically and comprehensively reviews the research and development of WHR CPVT systems. WHR CPVT systems with innovative design configurations, different theoretical evaluation models and experimental test processes for several implementations are presented in an integrated manner. We aim to provide a global point of view on the research trends, market potential, technical obstacles, and the future work which is required in the development of WHR CPVT technology. Possibly, it will offer a generic guide to the investigators who are interested in the study of WHR CPVT systems.展开更多
This paper presents an experimental evaluation of a specially designed falling particle receiver. A quartz tube was used in the design, with which the particles would not be blown away by wind. Concentrated solar radi...This paper presents an experimental evaluation of a specially designed falling particle receiver. A quartz tube was used in the design, with which the particles would not be blown away by wind. Concentrated solar radiation was absorbed and converted into thermal energy by the solid particles flowed inside the quartz tube. Several experiments were conducted to test the dynamic thermal performance of the receiver on solar furnace system. During the experiments, the maximum particle temperature rise is 212~C, with an efficiency of 61.2%, which shows a good thermal performance with a falling distance of 0.2 m in a small scale particle receiver. The average outlet particle temperature is affected by direct normal irradiance (DNI) and other factors such as wind speed. The solid particles obtain a larger viscosity with a higher temperature while smaller solid particles are easier to get stuck in the helix quartz tube. The heat capacity of the silicon carbide gets larger with the rise of particle temperature, because as the temperature of solid particles increases, the temperature rise of the silicon carbide decreases.展开更多
The aim of the study is to investigate the influence of geometry on the thermal capacity and stratifications of a water pit heat storage for solar district heating.A TRNSYS component model for a truncated cone water p...The aim of the study is to investigate the influence of geometry on the thermal capacity and stratifications of a water pit heat storage for solar district heating.A TRNSYS component model for a truncated cone water pit was developed based on the coordinate transformation method and validated by experimental results from the water pit heat storage in Huangdicheng in 2018.The thermal performance of 26 water pits with different heights and side wall slopes was calculated for 10 consecutive years.It takes four to six years for the water pit to reach steady-state operation.The operation data from the tenth year was selected to evaluate the thermal performance of each configuration.The results show that because of the thermal insulation on top of the water pit,the height to diameter ratio of a water pit with minimum annual heat loss was always smaller than 1.0.The annual storage efficiency of a water pit increases with side wall slope due to the reduced side wall area.There is an almost linear increase in the thermal stratification number of a water pit with height.With an increase in the height,thermal stratification in water pits with a steeper slope increased more gradually than water pits with a lower slope.The findings in this paper are relevant for the design optimization of water pits as seasonal thermal energy storages.展开更多
Since December 2019,an increasing number of cases of pneumonia with unknown etiology(PUE)—later named as coronavirus disease 2019(COVID-19)by the World Health Organization(WHO)—was identified in Wuhan(1–3),a large ...Since December 2019,an increasing number of cases of pneumonia with unknown etiology(PUE)—later named as coronavirus disease 2019(COVID-19)by the World Health Organization(WHO)—was identified in Wuhan(1–3),a large city of 11 million people in central China,and the basic reproductive number(R0)was estimated to be 2.2(95%CI:1.4 to 3.9)(4).On March 11,2020,the WHO formally announced COVID-19 a worldwide pandemic based on the alarming levels of spread and severity and by the alarming levels of inaction(5).Although there is neither a vaccine nor specific medication available,the pandemic was well contained in China by the strict introduction of nonpharmacological interventions(NPIs)(6).展开更多
基金Yunnan Expert Workstation,Grant/Award Number:202005AF150028Program for the Outstanding Young Talents of Hebei Province,China,Grant/Award Number:YGZ+6 种基金Guangdong Innovative and Entrepreneurial Team Program,Grant/Award Number:2016ZT06C517Guangdong Science and Technology Department,Grant/Award Number:2020B0909030004National Natural Science Foundation of China,Grant/Award Numbers:21601136,22075211,52071125Outstanding Youth Project of Guangdong Natural Science Foundation,Grant/Award Number:2021B1515020051Natural Science Foundation of Hebei Province,China,Grant/Award Numbers:B2020202052,B2021202028,E2020202071Chunhui Project of Ministry of Education of the People's Republic of China,Grant/Award Number:Z2017010Science and Technology Program of Guangzhou,Grant/Award Number:2019050001。
文摘Due to low cost,high capacity,and high energy density,lithium–sulfur(Li–S)batteries have attracted much attention;however,their cycling performance was largely limited by the poor redox kinetics and low sulfur utilization.Herein,predicted by density functional theory calculations,single‐atomic Co‐B2N2 site‐imbedded boron and nitrogen co‐doped carbon nanotubes(SA‐Co/BNC)were designed to accomplish high sulfur loading,fast kinetic,and long service period Li–S batteries.Experiments proved that Co‐B2N2 atomic sites can effectively catalyze lithium polysulfide conversion.Therefore,the electrodes delivered a specific capacity of 1106 mAh g−1 at 0.2 C after 100 cycles and exhibited an outstanding cycle performance over 1000 cycles at 1 C with a decay rate of 0.032%per cycle.Our study offers a new strategy to couple the combined effect of nanocarriers and single‐atomic catalysts in novel coordination environments for high‐performance Li–S batteries.
文摘As a knowledge-intensive and promising strategic emerging industry, the biomedical industry has high entry thresholds, large R&D investment, long cycle, high risk and high return. In all technical fields, the biomedical industry has the highest dependence on intellectual property rights, and the protection of pharmaceutical intellectual property rights by domestic and foreign biomedical enterprises also runs through the whole process of drug research and development. Extending the patent protection period of drugs as well as forming and strengthening patent fortresses requires a patent network that surrounds drugs to maximize the value of intellectual property protection, which is also the focus of every pharmaceutical company with patent rights. By analyzing the patent portfolio of Clovis Oncology Company in the United States on Rucaparib and the patent portfolio of other companies or applicants on Rucaparib, we can have a clearer understanding of the strategy of extending the patent protection period of a new drug product.
文摘A 40 Gb/s high speed optical transmission system is designed, and the different dispersion compensation schemes are adopted to realize the transmission of the optical duo-binary (ODB) signals over 120 km optical fiber. Optical duo-binary signals are generated by using a precoder, two low- pass filters (LPF) and one mach-zehnder modulator (MZM). Through combination of dispersion compensation fiber (DCF) and single mode fiber (SMF) in the transmission link, four different dispersion compensation schemes (pre-compensation, post-compensation and hybrid compensation (pre+ post) and hybrid compensation (post+ pre)) were compared. Analyzing Q factor, BER, eye diagrams and receiver sensitivity in several dispersion compensation schemes, the simulation results are: the cut-off frequency of LPF affects the transmission performance, and the hybrid compensation (post+ pre) scheme is the optimal dispersion compensation method.
文摘In this article, the peak to average power ratio (PAPR) performance of 8 quadrature amplitude modulation-orthogonal frequency division multiplexing (8QAM-OFDM) optical signals has been researched in broadband optical access system. The complementary cumulative distribution functions (CCDFs) are analyzed of two different 8QAM-OFDMsignals with 16, 32, 64, 128, 256, 512 sub- carriers by simulation. The simulation results show that, with the increase of the number of subcarrier, the PAPR value becomes higher. When the numbers of subcarrier are16 and 512, the PAPR of 8QAM-OFDM optical signals are smaller than 5.2 dB and 5.3 dB respectively. Hence, the number of sub-carriers should be chosen according to practical application.
文摘Free Space Optical (FSO) communication is one of the most promising access methods. But, the different weather conditions will affect the transceiver performance. In this paper, we build a FSO communication system with 16-ary phase shift key-orthogonal frequency division multiplexing (16PSK-OFDM) downstream signals. We analyze the transmission performance of 16PSK-OFDM optical signals under five different weather conditions (sunny, light rain, moderate rain, snow, and fog). The optical spectral diagrams, constellation diagrams, and bit error rate (BER) of the received signals are simulation measured and analyzed. The results show that the constellation diagram under sunny condition is clear, and the value of BER is about 10?4.2 after 16PSK-OFDM optical signals pass through 500 m FSO link. Note that, the constellation points are dispersed under the other weather conditions.
文摘In this paper, the downstream transmission performance of two types of 8QAM-OFDM optical signals in broadband optical access system has been analyzed. After modulation and coding, two types of 10 Gbit/s 8QAM-OFDM optical access signals are downstream transmitted over 1 km, 10 km, 20 km and 40 km single mode fibers (SMFs) and received successfully. Different transmission distances impact on the bit error rate (BER) of the received signal is analyzed by simulation, while the signal to noise ratio (SNR) is 20 dB. The results show that, while the transmission distance is shorter than 10 km, the BER values of two types of 8QAM-OFDM optical signals are smaller than 10?10. As the above optical access signals are transmitted over 40 km SMF, the BER value of the first type of 8QAM-OFDM signals is bigger than 10?6, and the BER of the other type of 8QAM-OFDM signals is smaller than 10?6.
文摘In this paper, the transceiver performance of optical 64QAM-OFDM signals with different sub-car- riers is studied. Firstly, we build a 40Gbit/s optical coherent 64QAM-OFDM transmission system. 64QAM-OFDM optical signals with 16, 32, 64, 64, 128, 256 and 512 sub-carriers are transmitted over 100 km single mode fiber (SMF). Then, the optical spectrum diagrams before and after transmission, the bit error rate (BER) and constellation diagrams of received signals were compared. The simulation results show that, with the number of sub-carriers increasing, the value of PAPR will gradually increase and the quality of the received optical signals will deteriorate. Moreover, with the number of sub-carriers increasing, the computational complexity will increase when digital signal processing (DSP) is used. Therefore, we should choose the optimal number of sub-carriers, and the PAPR influence and BER are also considered for achieving effective transmission.
基金supported in part by the State Major Science and Technology Special Project(Grant No.2018ZX03001025)the National Natural Science Foundation of China(No.61831002 and No.61671074)the Fundamental Research Funds for the Central Universities under Grant No.2018XKJC01
文摘Coordinated signal processing can obtain a huge transmission gain for Fog Radio Access Networks(F-RANs).However,integrating into large scale,it will lead to high computation complexity in channel estimation and spectral efficiency loss in transmission performance.Thus,a joint cluster formation and channel estimation scheme is proposed in this paper.Considering research remote radio heads(RRHs)centred serving scheme,a coalition game is formulated in order to maximize the spectral efficiency of cooperative RRHs under the conditions of balancing the data rate and the cost of channel estimation.As the cost influences to the necessary consumption of training length and estimation error.Particularly,an iterative semi-blind channel estimation and symbol detection approach is designed by expectation maximization algorithm,where the channel estimation process is initialized by subspace method with lower pilot length.Finally,the simulation results show that a stable cluster formation is established by our proposed coalition game method and it outperforms compared with full coordinated schemes.
基金supported by National Natural Science Foundation of China(No.10776037)
文摘A novel method was reported to measure the remnant magnetic field in Lorentz mode in a FEI Tecnai F20 transmission electron microscope equipped with a Lorentz lens. The movement of the circle Bloch line of the cross-tie wall in Permalloy is used to measure the remnant magnetic field by tilting the specimen and adjusting the objective lens current. The remnant magnetic field is estimated to be about 17 Oe, in a direction opposite to that of the objective lens magnetic field. The remnant magnetic field can be compensated by adjusting the value of the objective lens current.
基金This work was supported by the National Natural Science Foundation of China(Grant No.61300055,U1736215,61672302)Zhejiang Natural Science Foundation(Grant No.LY17F020010,LZ15F020002)+1 种基金Ningbo Natural Science Foundation(Grant No.2017A610123)Ningbo University Fund(Grant No.XKXL1509,XKXL1503)and K.C.Wong Magna Fund in Ningbo University.
文摘Speech resampling is a typical tempering behavior,which is often integrated into various speech forgeries,such as splicing,electronic disguising,quality faking and so on.By analyzing the principle of resampling,we found that,compared with natural speech,the inconsistency between the bandwidth of the resampled speech and its sampling ratio will be caused because the interpolation process in resampling is imperfect.Based on our observation,a new resampling detection algorithm based on the inconsistency of band energy is proposed.First,according to the sampling ratio of the suspected speech,a band-pass Butterworth filter is designed to filter out the residual signal.Then,the logarithmic ratio of band energy is calculated by the suspected speech and the filtered speech.Finally,with the logarithmic ratio,the resampled and original speech can be discriminated.The experimental results show that the proposed algorithm can effectively detect the resampling behavior under various conditions and is robust to MP3 compression.
基金supported by the National Natural Science Foundation of China(32130072)the Chinese Academy of Sciences’Strategic Priority Research Program(XDB27020104)the National Key Research and Development Program(2021YFD2200204).
文摘Primary and secondary growth of the tree stem are responsible for corresponding increases in trunk height and diameter.However,our molecular understanding of the biological processes that underlie these two types of growth is incomplete.In this study,we used single-cell RNA sequencing and spatial transcriptome sequencing to reveal the transcriptional landscapes of primary and secondary growth tissues in the Populus stem.Comparison between the cell atlas and differentiation trajectory of primary and secondary growth revealed different regulatory networks involved in cell differentiation from cambium to xylem precursors and phloem precursors.These regulatory networks may be controlled by auxin accumulation and distribution.Analysis of cell differentiation trajectories suggested that vessel and fiber development followed a sequential pattern of progressive transcriptional regulation.This research provides new insights into the processes of cell identity and differentiation that occur throughout primary and secondary growth of tree stems,increasing our understanding of the cellular differentiation dynamics that occur during stemgrowth in trees.
基金supported by the National Natural Science Foundation of China (51406051 and 51522602)the Beijing Municipal Science and Technology Project (Z161100002616039)the Fundamental Research Funds for the Central Universities (2016MS20)
文摘In conventional photovoltaic(PV) systems, a large portion of solar energy is dissipated as waste heat since the generating efficiency is usually less than 30%. As the dissipated heat can be recovered for various applications, the wasted heat recovery concentrator PV/thermal(WHR CPVT) hybrid systems have been developed. They can provide both electricity and usable heat by combining thermal systems with concentrator PV(CPV) module, which dramatically improves the overall conversion efficiency of solar energy.This paper systematically and comprehensively reviews the research and development of WHR CPVT systems. WHR CPVT systems with innovative design configurations, different theoretical evaluation models and experimental test processes for several implementations are presented in an integrated manner. We aim to provide a global point of view on the research trends, market potential, technical obstacles, and the future work which is required in the development of WHR CPVT technology. Possibly, it will offer a generic guide to the investigators who are interested in the study of WHR CPVT systems.
文摘This paper presents an experimental evaluation of a specially designed falling particle receiver. A quartz tube was used in the design, with which the particles would not be blown away by wind. Concentrated solar radiation was absorbed and converted into thermal energy by the solid particles flowed inside the quartz tube. Several experiments were conducted to test the dynamic thermal performance of the receiver on solar furnace system. During the experiments, the maximum particle temperature rise is 212~C, with an efficiency of 61.2%, which shows a good thermal performance with a falling distance of 0.2 m in a small scale particle receiver. The average outlet particle temperature is affected by direct normal irradiance (DNI) and other factors such as wind speed. The solid particles obtain a larger viscosity with a higher temperature while smaller solid particles are easier to get stuck in the helix quartz tube. The heat capacity of the silicon carbide gets larger with the rise of particle temperature, because as the temperature of solid particles increases, the temperature rise of the silicon carbide decreases.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA21050200)the Guangdong Innovative and Entrepreneurial Research Team Program(No.2013N070)the State Grid Corporation Science and Technology Project“Research on Comprehensive Development and Utilization Technology of Renewable Energy in Multi-format Ecological Development Zone”for funding this project.
文摘The aim of the study is to investigate the influence of geometry on the thermal capacity and stratifications of a water pit heat storage for solar district heating.A TRNSYS component model for a truncated cone water pit was developed based on the coordinate transformation method and validated by experimental results from the water pit heat storage in Huangdicheng in 2018.The thermal performance of 26 water pits with different heights and side wall slopes was calculated for 10 consecutive years.It takes four to six years for the water pit to reach steady-state operation.The operation data from the tenth year was selected to evaluate the thermal performance of each configuration.The results show that because of the thermal insulation on top of the water pit,the height to diameter ratio of a water pit with minimum annual heat loss was always smaller than 1.0.The annual storage efficiency of a water pit increases with side wall slope due to the reduced side wall area.There is an almost linear increase in the thermal stratification number of a water pit with height.With an increase in the height,thermal stratification in water pits with a steeper slope increased more gradually than water pits with a lower slope.The findings in this paper are relevant for the design optimization of water pits as seasonal thermal energy storages.
文摘Since December 2019,an increasing number of cases of pneumonia with unknown etiology(PUE)—later named as coronavirus disease 2019(COVID-19)by the World Health Organization(WHO)—was identified in Wuhan(1–3),a large city of 11 million people in central China,and the basic reproductive number(R0)was estimated to be 2.2(95%CI:1.4 to 3.9)(4).On March 11,2020,the WHO formally announced COVID-19 a worldwide pandemic based on the alarming levels of spread and severity and by the alarming levels of inaction(5).Although there is neither a vaccine nor specific medication available,the pandemic was well contained in China by the strict introduction of nonpharmacological interventions(NPIs)(6).