This paper conducts comprehensive analysis about operational characteristics, market value, stakeholders, and operating modes of a megacity energy Internet. An innovating 'one platform, two centers, and multiple n...This paper conducts comprehensive analysis about operational characteristics, market value, stakeholders, and operating modes of a megacity energy Internet. An innovating 'one platform, two centers, and multiple nodes' operation management model is proposed. The study provides an in-depth explanation of the new operation and management model of the connotation and logical relationship. Building a comprehensive energy service platform, developing an integrated energy dispatch center, a market trading service center, communication, and other parts of the system needed to achieve benefits for all parties is including in the discussion. The proposed new model of operation and management has important guiding significance and reference for the development and construction of energy Internets in megacities.展开更多
If a failure in the components of a photovoltaic(PV)system,such as PV module,controller,inverter,load,cable,etc.goes undetected and uncorrected,it can seriously affect the efficiency,safety,and reliability of the enti...If a failure in the components of a photovoltaic(PV)system,such as PV module,controller,inverter,load,cable,etc.goes undetected and uncorrected,it can seriously affect the efficiency,safety,and reliability of the entire PV power plant.In addition,fires can occur if specific faults,such as arc,ground,and line-to-line faults remain unresolved.Therefore,PV system(PVS)fault diagnoses are crucial for PV power plant reliability,efficiency,and safety.Many fault diagnosis methods and techniques for PVS components have been developed.In addition,with the development of PV devices,more advanced and intelligent diagnostic technologies are continuously being researched and developed.However,a systematic and thorough analysis,summary,and conclusion are still urgently required.Thus,this paper introduces the types,causes,and impacts of PVS faults,and reviews and discusses the methods proposed in the literature for PVS fault diagnosis,and in particular,failures in PV arrays.Special attention is paid to the optimization direction of various fault diagnosis methods under different priorities,and their limitations,feasibility,complexity,and cost-effectiveness.Finally,challenges and suggestions are put forward for future research.展开更多
In this paper,a collaborative online algo-rithm is proposed to estimate the state of charge(SOC)and state of health(SOH)of leadcarbon batteries that participate in frequency regulation of a power system with a high pr...In this paper,a collaborative online algo-rithm is proposed to estimate the state of charge(SOC)and state of health(SOH)of leadcarbon batteries that participate in frequency regulation of a power system with a high proportion of renewable energy.The algo-rithm addresses the inaccurate estimation of energy storage battery states caused by continuous and alter-nating charging and discharging over a short period.Analysis of lead-carbon battery chemistry and materials reveals that the resistance of the diaphragm is the most influential factor in battery aging.In addition,the hyste-resis characteristics of an energy storage battery vary significantly between the charging and discharging stages.A second-order RC equivalent circuit model is proposed that considers the contact and diaphragm resistances,and hysteresis characteristics.Based on this,models for constant current charging interaction,constant voltage charging interaction,and dynamic discharging interaction are developed.The adaptive forgetting factor recursive least square(AFF-RLS)method is used to identify the parameters of the interactive models.Then an interactive multiple model with the embedded unscented Kalman filter(UKF)is used to estimate the SOC of the energy storage battery.The membrane and contact resistances identified by the interactive multi-model(IMM)are used to estimate the SOH,and online collaborative optimization of the SOC and SOH is achieved.The error of the proposed SOC estimation method is experimentally verified to be within 2%,which is less than 5%of the standard value,and the error of SOH estimation is within 0.5%,demonstrating the high accuracy of the proposed method.展开更多
Using an optical interferometric technique,the grease film distribution under a pure rolling reciprocating motion is observed on a ball‐disk test rig,to explore the transient response of grease,which is expected to f...Using an optical interferometric technique,the grease film distribution under a pure rolling reciprocating motion is observed on a ball‐disk test rig,to explore the transient response of grease,which is expected to fill the contact with thickener fiber and run for a long time under steady‐state conditions.It is found that the reciprocating motion reduces the accumulation of the thickener fiber gradually with time.The maximum film thickness forms around the stroke ends.After 1,000 working cycles,very severe starvation occurs so that either the central or minimum film thickness becomes nearly constant over one working period.Thus,the life of grease lubrication under a transient condition is far below that under steady‐state conditions.However,it is also found that by selecting a smaller stroke length,the thickener fiber spreads out in the contact instead of being removed from the contact at the 1,000th working period.When increasing the maximum entraining speed of the reciprocating motion to a certain value,during which the thickener fiber is not expected to accumulate under a steady‐state condition,severe starvation occurs very quickly,causing surface damage.展开更多
Hemostasis is a major challenge in surgical procedures and traumas. Conventional hemostatic methods have limited efficacy and may cause additional tissue damage. In this study, we designed a novel hemostatic agent bas...Hemostasis is a major challenge in surgical procedures and traumas. Conventional hemostatic methods have limited efficacy and may cause additional tissue damage. In this study, we designed a novel hemostatic agent based on the in situ gel formation of gelatin cross-linked by a novel microbial transglutaminase(mTGase), in which the amino acid sequences differed from commercial mTGases. The new hemostatic agent showed the same biochemical crosslinking chemistry as the final stages of the blood coagulation cascade while using gelatin as a "structural" protein(rather than fibrin) and a calcium-independent mTGase as the crosslinking catalyst(rather than factor XIIIa). In rat liver hemostasis models, the hemostatic agent not only showed a similar hemostatic effect as that of SURGIFLO~(positive control), but also stronger adhesion strength and elasticity than SURGIFLO~.Therefore, this biomimetic gelatin-mTGase mix hemostatic is a novel and effective surgical sealant.展开更多
基金supported by the National Key R&D Program of China(2016YFB09005002016YFB0900905)
文摘This paper conducts comprehensive analysis about operational characteristics, market value, stakeholders, and operating modes of a megacity energy Internet. An innovating 'one platform, two centers, and multiple nodes' operation management model is proposed. The study provides an in-depth explanation of the new operation and management model of the connotation and logical relationship. Building a comprehensive energy service platform, developing an integrated energy dispatch center, a market trading service center, communication, and other parts of the system needed to achieve benefits for all parties is including in the discussion. The proposed new model of operation and management has important guiding significance and reference for the development and construction of energy Internets in megacities.
基金supported by the National Natural Science Foundation of China(No.61963020 and No.62263014)Yunnan Provincial Basic Research Project(No.202401AT070344 and No.202301AT070443).
文摘If a failure in the components of a photovoltaic(PV)system,such as PV module,controller,inverter,load,cable,etc.goes undetected and uncorrected,it can seriously affect the efficiency,safety,and reliability of the entire PV power plant.In addition,fires can occur if specific faults,such as arc,ground,and line-to-line faults remain unresolved.Therefore,PV system(PVS)fault diagnoses are crucial for PV power plant reliability,efficiency,and safety.Many fault diagnosis methods and techniques for PVS components have been developed.In addition,with the development of PV devices,more advanced and intelligent diagnostic technologies are continuously being researched and developed.However,a systematic and thorough analysis,summary,and conclusion are still urgently required.Thus,this paper introduces the types,causes,and impacts of PVS faults,and reviews and discusses the methods proposed in the literature for PVS fault diagnosis,and in particular,failures in PV arrays.Special attention is paid to the optimization direction of various fault diagnosis methods under different priorities,and their limitations,feasibility,complexity,and cost-effectiveness.Finally,challenges and suggestions are put forward for future research.
基金supported by the National Natural Science Foundation of China(52037003)the Major Special and Technology Project of Yunnan Province(202002AF080001).
文摘In this paper,a collaborative online algo-rithm is proposed to estimate the state of charge(SOC)and state of health(SOH)of leadcarbon batteries that participate in frequency regulation of a power system with a high proportion of renewable energy.The algo-rithm addresses the inaccurate estimation of energy storage battery states caused by continuous and alter-nating charging and discharging over a short period.Analysis of lead-carbon battery chemistry and materials reveals that the resistance of the diaphragm is the most influential factor in battery aging.In addition,the hyste-resis characteristics of an energy storage battery vary significantly between the charging and discharging stages.A second-order RC equivalent circuit model is proposed that considers the contact and diaphragm resistances,and hysteresis characteristics.Based on this,models for constant current charging interaction,constant voltage charging interaction,and dynamic discharging interaction are developed.The adaptive forgetting factor recursive least square(AFF-RLS)method is used to identify the parameters of the interactive models.Then an interactive multiple model with the embedded unscented Kalman filter(UKF)is used to estimate the SOC of the energy storage battery.The membrane and contact resistances identified by the interactive multi-model(IMM)are used to estimate the SOH,and online collaborative optimization of the SOC and SOH is achieved.The error of the proposed SOC estimation method is experimentally verified to be within 2%,which is less than 5%of the standard value,and the error of SOH estimation is within 0.5%,demonstrating the high accuracy of the proposed method.
基金supported by the National Natural Science Foundation of China through grants No.51875298 and No.51275253
文摘Using an optical interferometric technique,the grease film distribution under a pure rolling reciprocating motion is observed on a ball‐disk test rig,to explore the transient response of grease,which is expected to fill the contact with thickener fiber and run for a long time under steady‐state conditions.It is found that the reciprocating motion reduces the accumulation of the thickener fiber gradually with time.The maximum film thickness forms around the stroke ends.After 1,000 working cycles,very severe starvation occurs so that either the central or minimum film thickness becomes nearly constant over one working period.Thus,the life of grease lubrication under a transient condition is far below that under steady‐state conditions.However,it is also found that by selecting a smaller stroke length,the thickener fiber spreads out in the contact instead of being removed from the contact at the 1,000th working period.When increasing the maximum entraining speed of the reciprocating motion to a certain value,during which the thickener fiber is not expected to accumulate under a steady‐state condition,severe starvation occurs very quickly,causing surface damage.
基金supported by the National Basic Research Program of China (2015CB910400, 2012CB910400)National Natural Science Foundation of China (81472788, 81272463, 81330049)
文摘Hemostasis is a major challenge in surgical procedures and traumas. Conventional hemostatic methods have limited efficacy and may cause additional tissue damage. In this study, we designed a novel hemostatic agent based on the in situ gel formation of gelatin cross-linked by a novel microbial transglutaminase(mTGase), in which the amino acid sequences differed from commercial mTGases. The new hemostatic agent showed the same biochemical crosslinking chemistry as the final stages of the blood coagulation cascade while using gelatin as a "structural" protein(rather than fibrin) and a calcium-independent mTGase as the crosslinking catalyst(rather than factor XIIIa). In rat liver hemostasis models, the hemostatic agent not only showed a similar hemostatic effect as that of SURGIFLO~(positive control), but also stronger adhesion strength and elasticity than SURGIFLO~.Therefore, this biomimetic gelatin-mTGase mix hemostatic is a novel and effective surgical sealant.
