[Objectives]To study the microscopic characteristics and routine detection of Hedyotis hedyotidea(DC.)Merr.[Methods]The microscopic characteristics of the root,stem cross section and the whole plant powder of H.hedyot...[Objectives]To study the microscopic characteristics and routine detection of Hedyotis hedyotidea(DC.)Merr.[Methods]The microscopic characteristics of the root,stem cross section and the whole plant powder of H.hedyotidea were studied by the methods of slide-shaft section,biological staining and microscopic imaging;the routine detection items such as moisture,ash,acid-insoluble ash and extract were detected and analyzed in accordance with the requirements of Chinese Pharmacopoeia.[Results]The microscopic characteristics of the root,the stem and the whole plant powder of H.hedyotidea were obtained.The moisture content of 10 batches of H.hedyotidea samples was in the range of 4.25%-7.90%,the water-soluble extract is in the range of 15.08%-22.52%,the total ash was in the scope of 8.27%-10.45%,and the acid-insoluble ash was in 0.13%-0.95%.The proposed water content of H.hedyotidea should not exceed 10.00%,the water-soluble extract should not be less than 12.00%,the total ash content should not exceed 13.00%,and the acid-insoluble ash content should not exceed 1.20%.[Conclusions]The results of this experiment can provide a reference for the quality control and quality standard of H.hedyotidea.展开更多
Single zinc oxide nanowires(ZnO NWs)are promising for nanogenerators because of their excellent semiconducting and piezoelectric properties,but characterizing the latter efficiently is challenging.As reported here,an ...Single zinc oxide nanowires(ZnO NWs)are promising for nanogenerators because of their excellent semiconducting and piezoelectric properties,but characterizing the latter efficiently is challenging.As reported here,an electrical breakdown strategy was used to construct single ZnO NWs with a specific length.With the high operability of a nanomanipulator in a scanning electron microscope,ZnO-NW-based twoprobe and three-probe structures were constructed for fabricating AC/DC nanogenerators,respectively.For a ZnO NW,an AC output of between−15.31 mV and 5.82 mV was achieved,while for a DC nanogenerator,an output of24.3 mV was realized.Also,the three-probe structure’s output method was changed to verify the distribution of piezoelectric charges when a single ZnO NW is bent by a probe,and DC outputs of different amplitudes were achieved.This study provides a low-cost,highly convenient,and operational method for studying the AC/DC output characteristics of single NWs,which is beneficial for the further development of nanogenerators.展开更多
This article presents an ongoing study of the design of a DC-AC inverter using a single renewable energy source. The proposed approach makes it possible to produce an output with an H-bridge or full bridge and a singl...This article presents an ongoing study of the design of a DC-AC inverter using a single renewable energy source. The proposed approach makes it possible to produce an output with an H-bridge or full bridge and a single energy source. To this end, the performance of the inverter was studied first by means of a simulation and then with the implementation of an experimental device.展开更多
ADC distribution network is an effective solution for increasing renewable energy utilization with distinct benefits,such as high efficiency and easy control.However,a sudden increase in the current after the occurren...ADC distribution network is an effective solution for increasing renewable energy utilization with distinct benefits,such as high efficiency and easy control.However,a sudden increase in the current after the occurrence of faults in the network may adversely affect network stability.This study proposes an artificial neural network(ANN)-based fault detection and protection method for DC distribution networks.The ANN is applied to a classifier for different faults ontheDC line.The backpropagationneuralnetwork is used to predict the line current,and the fault detection threshold is obtained on the basis of the difference between the predicted current and the actual current.The proposed method only uses local signals,with no requirement of a strict communication link.Simulation experiments are conducted for the proposed algorithm on a two-terminal DC distribution network modeled in the PSCAD/EMTDC and developed on the MATLAB platform.The results confirm that the proposed method can accurately detect and classify line faults within a few milliseconds and is not affected by fault locations,fault resistance,noise,and communication delay.展开更多
Within the roadway advanced detection methods, DC resistivity method has an extensive application because of its simple principle and operation. Numerical simulation of the effect of focusing current on advanced detec...Within the roadway advanced detection methods, DC resistivity method has an extensive application because of its simple principle and operation. Numerical simulation of the effect of focusing current on advanced detection was carried out using a three-dimensional finite element method （FEM）, meanwhile the electric-field distribution of the point source and nine-point power source were calculated and analyzed with the same electric charges. The results show that the nine-point power source array has a very good ability to focus, and the DC focus method can be used to predict the aquifer abnormality body precisely. By comparing the FEM modelling results with physical simulation results from soil sink, it is shown that the accuracy of forward simulation meets the requirement and the artificial disturbance from roadway has no impact on the DC focus method.展开更多
针对电动汽车充电电源额外热量产生影响电池使用寿命的问题,提出一种无电解电容隔离式单级双向AC/DC变换器。该变换器能有效阻止低频功率纹波注入电池单元,减少了额外热量的产生;同时电解电容的消除也大大提高了系统的可靠性。控制策略...针对电动汽车充电电源额外热量产生影响电池使用寿命的问题,提出一种无电解电容隔离式单级双向AC/DC变换器。该变换器能有效阻止低频功率纹波注入电池单元,减少了额外热量的产生;同时电解电容的消除也大大提高了系统的可靠性。控制策略方面,提出的一种四相控制器,不仅能使所有开关管实现零电压开关(Zero Voltage Switch,ZVS),并在导通损耗进行了性能优化。最后,通过PSIM仿真软件和实验样机,验证了理论分析的正确性和可行性。展开更多
基金Supported by 2019-2021 Guangxi First-class Discipline Construction Open Project of Guangxi University of Chinese Medicine(2019XK096).
文摘[Objectives]To study the microscopic characteristics and routine detection of Hedyotis hedyotidea(DC.)Merr.[Methods]The microscopic characteristics of the root,stem cross section and the whole plant powder of H.hedyotidea were studied by the methods of slide-shaft section,biological staining and microscopic imaging;the routine detection items such as moisture,ash,acid-insoluble ash and extract were detected and analyzed in accordance with the requirements of Chinese Pharmacopoeia.[Results]The microscopic characteristics of the root,the stem and the whole plant powder of H.hedyotidea were obtained.The moisture content of 10 batches of H.hedyotidea samples was in the range of 4.25%-7.90%,the water-soluble extract is in the range of 15.08%-22.52%,the total ash was in the scope of 8.27%-10.45%,and the acid-insoluble ash was in 0.13%-0.95%.The proposed water content of H.hedyotidea should not exceed 10.00%,the water-soluble extract should not be less than 12.00%,the total ash content should not exceed 13.00%,and the acid-insoluble ash content should not exceed 1.20%.[Conclusions]The results of this experiment can provide a reference for the quality control and quality standard of H.hedyotidea.
基金supported by the Research Fund Program of the Guangdong Provincial Key Laboratory of Fuel Cell Technology (Grant No.FC202204).
文摘Single zinc oxide nanowires(ZnO NWs)are promising for nanogenerators because of their excellent semiconducting and piezoelectric properties,but characterizing the latter efficiently is challenging.As reported here,an electrical breakdown strategy was used to construct single ZnO NWs with a specific length.With the high operability of a nanomanipulator in a scanning electron microscope,ZnO-NW-based twoprobe and three-probe structures were constructed for fabricating AC/DC nanogenerators,respectively.For a ZnO NW,an AC output of between−15.31 mV and 5.82 mV was achieved,while for a DC nanogenerator,an output of24.3 mV was realized.Also,the three-probe structure’s output method was changed to verify the distribution of piezoelectric charges when a single ZnO NW is bent by a probe,and DC outputs of different amplitudes were achieved.This study provides a low-cost,highly convenient,and operational method for studying the AC/DC output characteristics of single NWs,which is beneficial for the further development of nanogenerators.
文摘This article presents an ongoing study of the design of a DC-AC inverter using a single renewable energy source. The proposed approach makes it possible to produce an output with an H-bridge or full bridge and a single energy source. To this end, the performance of the inverter was studied first by means of a simulation and then with the implementation of an experimental device.
基金supported by Key Natural Science Research Projects of Colleges and Universities in Anhui Province(No.2022AH051831).
文摘ADC distribution network is an effective solution for increasing renewable energy utilization with distinct benefits,such as high efficiency and easy control.However,a sudden increase in the current after the occurrence of faults in the network may adversely affect network stability.This study proposes an artificial neural network(ANN)-based fault detection and protection method for DC distribution networks.The ANN is applied to a classifier for different faults ontheDC line.The backpropagationneuralnetwork is used to predict the line current,and the fault detection threshold is obtained on the basis of the difference between the predicted current and the actual current.The proposed method only uses local signals,with no requirement of a strict communication link.Simulation experiments are conducted for the proposed algorithm on a two-terminal DC distribution network modeled in the PSCAD/EMTDC and developed on the MATLAB platform.The results confirm that the proposed method can accurately detect and classify line faults within a few milliseconds and is not affected by fault locations,fault resistance,noise,and communication delay.
基金Project(41174103)supported by the National Natural Science Foundation of ChinaProject(20110162130008)supported by the PhD Program Foundation of Ministry of Education of ChinaProject(2011BAB04B08)supported by the National Key Technology R&D Program during the 12th Five-Year Plan of China
文摘Within the roadway advanced detection methods, DC resistivity method has an extensive application because of its simple principle and operation. Numerical simulation of the effect of focusing current on advanced detection was carried out using a three-dimensional finite element method （FEM）, meanwhile the electric-field distribution of the point source and nine-point power source were calculated and analyzed with the same electric charges. The results show that the nine-point power source array has a very good ability to focus, and the DC focus method can be used to predict the aquifer abnormality body precisely. By comparing the FEM modelling results with physical simulation results from soil sink, it is shown that the accuracy of forward simulation meets the requirement and the artificial disturbance from roadway has no impact on the DC focus method.
文摘针对电动汽车充电电源额外热量产生影响电池使用寿命的问题,提出一种无电解电容隔离式单级双向AC/DC变换器。该变换器能有效阻止低频功率纹波注入电池单元,减少了额外热量的产生;同时电解电容的消除也大大提高了系统的可靠性。控制策略方面,提出的一种四相控制器,不仅能使所有开关管实现零电压开关(Zero Voltage Switch,ZVS),并在导通损耗进行了性能优化。最后,通过PSIM仿真软件和实验样机,验证了理论分析的正确性和可行性。
