The current research mainly focuses on the flow control for the two-stage proportional valve with hydraulic position feedback which is named as Valvistor valve.Essentially,the Valvistor valve is a proportional throttl...The current research mainly focuses on the flow control for the two-stage proportional valve with hydraulic position feedback which is named as Valvistor valve.Essentially,the Valvistor valve is a proportional throttle valve and the flow fluctuates with the change of load pressure.The flow fluctuation severely restricts the application of the Valvistor valve.In this paper,a novel flow control method the Valvistor valve is provided to suppress the flow fluctuation and develop a high performance proportional flow valve.The mathematical model of this valve is established and linearized.Fuzzy proportional-integral-derivative(PID)controller is adopted in the closed-loop flow control system.The feedback is obtained by the flow inference with back-propagation neural network(BPNN)based on the spool displacement in the pilot stage and the pressure differential across the main orifice.The results show that inference with BPNN can obtain the flow data fast and accurately.With the flow control method,the flow can keep at the set point when the pressure differential across the main orifice changes.The flow control method is effective and the Valvistor valve changes from proportional throttle valve to proportional flow valve.For the developed proportional flow valve,the settling time of the flow is very short when the load pressure changes abruptly.The performances of hysteresis,linearity and bandwidth are in a high range.The linear mathematical model can be verified and the assumptions in the system modeling is reasonable.展开更多
ZnO nanoparticles are widely used for the electron transport layers(ETLs)of quantum dots light emitting devices(QLEDs).In this work we show that incorporating fluorine(F)into the ZnO ETL results in significant enhance...ZnO nanoparticles are widely used for the electron transport layers(ETLs)of quantum dots light emitting devices(QLEDs).In this work we show that incorporating fluorine(F)into the ZnO ETL results in significant enhancement in device electroluminescence stability,leading to LT50 at 100 cd m^(−2) of 2,370,000 h in red QLED,47X longer than the control devices.X-ray photo-electron spectroscopy,time-of-flight secondary ion mass spectroscopy,photoluminescence and electrical measurements show that the F passivates oxygen vacancies and reduces electron traps in ZnO.Transient photoluminescence versus bias measurements and capacitance-voltage-luminance measurements reveal that the CF4 plasma-treated ETLs lead to increased electron concentration in the QD and the QD/hole transport layer interface,subsequently decreasing hole accumulation,and hence the higher stability.The findings provide new insights into the critical roles that optimizing charge distribution across the layers play in influencing stability and present a novel and simple approach for extending QLED lifetimes.展开更多
To solve the numerical divergence problem of the direct time domain Green function method for the motion simulation of floating bodies with large flare, a time domain hybrid Rankine-Green boundary element method is pr...To solve the numerical divergence problem of the direct time domain Green function method for the motion simulation of floating bodies with large flare, a time domain hybrid Rankine-Green boundary element method is proposed. In this numerical method, the fluid domain is decomposed by an imaginary control surface, at which the continuous condition should be satisfied. Then the Rankine Green function is adopted in the inner domain. The transient free surface Green function is applied in the outer domain, which is used to find the relationship between the velocity potential and its normal derivative for the inner domain. Besides, the velocity potential at the mean free surface between body surface and control surface is directly solved by the integration scheme. The wave exciting force is computed through the convolution integration with wave elevation, by introducing the impulse response function. Additionally, the nonlinear Froude-Krylov force and hydrostatic force, which is computed under the instantaneous incident wave free surface, are taken into account by the direct pressure integration scheme. The corresponding numerical computer code is developed and first used to compute the hydrodynamic coefficients of the hemisphere, as well as the time history of a ship with large flare; good agreement is obtained with the analytical solutions as well as the available numerical results. Then the hydrodynamic properties of a FPSO are studied. The hydrodynamic coefficients agree well with the results computed by the frequency method; the influence of the time interval and the truncated time is investigated in detail.展开更多
Beipanjiang Bridge is a long-span concrete arch bridges with stiffened skeleton(CABSS)in China.It has a fixed end arch with the span of 445 m and the rise of 100 m.To evaluate the rationality of the construction seque...Beipanjiang Bridge is a long-span concrete arch bridges with stiffened skeleton(CABSS)in China.It has a fixed end arch with the span of 445 m and the rise of 100 m.To evaluate the rationality of the construction sequence and the time-dependent behavior of CABSS,an experimental study of a model bridge was explored.But the measured displacement and stress ratios of arch rib between prototype and model bridge did not subject to linear similarity relation when the time-dependent behavior was considered.So,the three-dimensional finite element models were established,and verified by the measured data.Then,the displacements and stresses of the prototype and model were compared with each other,when the elastic analysis or coupling of temperature and shrinkage,creep effect was considered.Furthermore,a parametric study was studied.The results showed that when the temperature,shrinkage and creep effect of concrete are considered,the finite element analysis results of prototype and model agree well with the measured results.The displacement and stress ratios of prototype and model bridge in construction and bridge completed stage do not present the geometric similarity ratio 7.5 and 1.0,respectively.They are also much influenced by concrete predicting model and variation of temperature.展开更多
We presented a control strategy for tablet manufacturing processes based on continuous direct compression.The work was conducted by the experts of pharmaceutical companies,machine suppliers,academia,and regulatory aut...We presented a control strategy for tablet manufacturing processes based on continuous direct compression.The work was conducted by the experts of pharmaceutical companies,machine suppliers,academia,and regulatory authority in Japan.Among different items in the process,the component ratio and blended powder content were selected as the items requiring the control method specific to continuous manufacturing different from the conventional batch manufacturing.The control and management of the Loss in Weight(LIW)feeder were deemed the most important,and the Residence Time Distribution(RTD)model were regarded effective for setting the control range and for controlling of the LIW feeder.Based on these ideas,the concept of process control using RTD was summarized.展开更多
Herein,we report the fabrication of high-performance transparent quantum-dot light-emitting diodes(Tr-QLEDs)with ZnO/ZnMgO inorganic double electron-transport layers(ETLs).The ETLs effectively suppress the excess elec...Herein,we report the fabrication of high-performance transparent quantum-dot light-emitting diodes(Tr-QLEDs)with ZnO/ZnMgO inorganic double electron-transport layers(ETLs).The ETLs effectively suppress the excess electron injection and facilitate charge balance in the Tr-QLEDs.The thick ETLs as buffer layers can also withstand the plasma-induced damage during the indium tin oxide sputtering.These factors collectively contribute to the development of Tr-QLEDs with improved performance.As a result,our Tr-QLEDs with double ETLs exhibited a high transmittance of 82%at 550 nm and a record external quantum efficiency of 11.8%,which is 1.27 times higher than that of the devices with pure ZnO ETL.These results indicate that the developed ZnO/ZnMgO inorganic double ETLs could offer promising solutions for realizing high-efficiency Tr-QLEDs for next-generation display devices.展开更多
Restricted use of hazardous environmental chemicals is one important challenge that the semiconductor industry needs to face to improve its sustainability.Ovonic threshold switching(OTS)ternary compound materials used...Restricted use of hazardous environmental chemicals is one important challenge that the semiconductor industry needs to face to improve its sustainability.Ovonic threshold switching(OTS)ternary compound materials used in memory selector devices contain As and Se.Engineering these elements out of these materials requires significant research effort.To facilitate this process,we performed systematic material screening for As/Se-free ternary materials,based on ab-initio simulations.To limit the large amount of possible chemical compositions to fewer promising candidates,we used physics-based material parameter filters like material stability,electronic properties,or change in polarizability.The OTS gauge concept is introduced as a computed parameter to estimate the probability of a material to show an OTS behavior.As a result,we identified 35 As/Se-free ternary alloy compositions for stand-alone OTS memory applications,as well as 12 compositions for RRAM selector applications.This work aims seeding the development of As/Se-free OTS materials.展开更多
In this study,a jet cavitation device aimed at producing two-dimensional nanosheets was designed.The effects of cavitation generator type and jet pressure on the cavitation inception and intensity were examined by mon...In this study,a jet cavitation device aimed at producing two-dimensional nanosheets was designed.The effects of cavitation generator type and jet pressure on the cavitation inception and intensity were examined by monitoring the changes of sound pressure level(SPL).As such,the optimized cavitation generator with the best cavitation capability under the same ambient condition was determined.Further,BN and MoS 2,two kinds of layered materials,were exfoliated into individual flakes in aqueous solutions by this jet cavitation device.By investigating the morphology of these exfoliated flakes via scanning electron microscopy and transmission electron microscope,it was found that these pristine materials were mostly exfoliated into two-dimensional nanosheets,among which even monolayers were generally presented.This exfoliation process happened mainly due to the cavitation-induced intensive tensile stress acting on the layered materials.As graphene has been produced by this device successfully,it is anticipated that this jet cavitation device is suitable for producing other various two-dimensional nanosheets.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51805350)Key Technologies Research and Development Program of China(Grant No.2018YFB2001202)+1 种基金Natural Science Foundation of Shanxi Province of China(Grant No.201801D221226)Postdoctoral Science Foundation of China(Grant No.2019M651073).
文摘The current research mainly focuses on the flow control for the two-stage proportional valve with hydraulic position feedback which is named as Valvistor valve.Essentially,the Valvistor valve is a proportional throttle valve and the flow fluctuates with the change of load pressure.The flow fluctuation severely restricts the application of the Valvistor valve.In this paper,a novel flow control method the Valvistor valve is provided to suppress the flow fluctuation and develop a high performance proportional flow valve.The mathematical model of this valve is established and linearized.Fuzzy proportional-integral-derivative(PID)controller is adopted in the closed-loop flow control system.The feedback is obtained by the flow inference with back-propagation neural network(BPNN)based on the spool displacement in the pilot stage and the pressure differential across the main orifice.The results show that inference with BPNN can obtain the flow data fast and accurately.With the flow control method,the flow can keep at the set point when the pressure differential across the main orifice changes.The flow control method is effective and the Valvistor valve changes from proportional throttle valve to proportional flow valve.For the developed proportional flow valve,the settling time of the flow is very short when the load pressure changes abruptly.The performances of hysteresis,linearity and bandwidth are in a high range.The linear mathematical model can be verified and the assumptions in the system modeling is reasonable.
基金Partial support to this work by the Natural Sciences & Engineering Research Council of Canada (NSERC) is gratefully acknowledged
文摘ZnO nanoparticles are widely used for the electron transport layers(ETLs)of quantum dots light emitting devices(QLEDs).In this work we show that incorporating fluorine(F)into the ZnO ETL results in significant enhancement in device electroluminescence stability,leading to LT50 at 100 cd m^(−2) of 2,370,000 h in red QLED,47X longer than the control devices.X-ray photo-electron spectroscopy,time-of-flight secondary ion mass spectroscopy,photoluminescence and electrical measurements show that the F passivates oxygen vacancies and reduces electron traps in ZnO.Transient photoluminescence versus bias measurements and capacitance-voltage-luminance measurements reveal that the CF4 plasma-treated ETLs lead to increased electron concentration in the QD and the QD/hole transport layer interface,subsequently decreasing hole accumulation,and hence the higher stability.The findings provide new insights into the critical roles that optimizing charge distribution across the layers play in influencing stability and present a novel and simple approach for extending QLED lifetimes.
基金the financial support provided by the National Basic Research Program of China(No.2011CB3703)the National Natural Science Foundation of China(No.51079034)
文摘To solve the numerical divergence problem of the direct time domain Green function method for the motion simulation of floating bodies with large flare, a time domain hybrid Rankine-Green boundary element method is proposed. In this numerical method, the fluid domain is decomposed by an imaginary control surface, at which the continuous condition should be satisfied. Then the Rankine Green function is adopted in the inner domain. The transient free surface Green function is applied in the outer domain, which is used to find the relationship between the velocity potential and its normal derivative for the inner domain. Besides, the velocity potential at the mean free surface between body surface and control surface is directly solved by the integration scheme. The wave exciting force is computed through the convolution integration with wave elevation, by introducing the impulse response function. Additionally, the nonlinear Froude-Krylov force and hydrostatic force, which is computed under the instantaneous incident wave free surface, are taken into account by the direct pressure integration scheme. The corresponding numerical computer code is developed and first used to compute the hydrodynamic coefficients of the hemisphere, as well as the time history of a ship with large flare; good agreement is obtained with the analytical solutions as well as the available numerical results. Then the hydrodynamic properties of a FPSO are studied. The hydrodynamic coefficients agree well with the results computed by the frequency method; the influence of the time interval and the truncated time is investigated in detail.
基金Projects(20-JKKJ-17,18-JKKJ-05)supported by the Shanxi Communications Holding Group Co.,Ltd.,ChinaProject(41907239)supported by the National Natural Science Foundation of China+1 种基金Project(2020M670698)supported by the China Postdoctoral Science FoundationProject(2019L0295)supported by the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi,China。
文摘Beipanjiang Bridge is a long-span concrete arch bridges with stiffened skeleton(CABSS)in China.It has a fixed end arch with the span of 445 m and the rise of 100 m.To evaluate the rationality of the construction sequence and the time-dependent behavior of CABSS,an experimental study of a model bridge was explored.But the measured displacement and stress ratios of arch rib between prototype and model bridge did not subject to linear similarity relation when the time-dependent behavior was considered.So,the three-dimensional finite element models were established,and verified by the measured data.Then,the displacements and stresses of the prototype and model were compared with each other,when the elastic analysis or coupling of temperature and shrinkage,creep effect was considered.Furthermore,a parametric study was studied.The results showed that when the temperature,shrinkage and creep effect of concrete are considered,the finite element analysis results of prototype and model agree well with the measured results.The displacement and stress ratios of prototype and model bridge in construction and bridge completed stage do not present the geometric similarity ratio 7.5 and 1.0,respectively.They are also much influenced by concrete predicting model and variation of temperature.
文摘We presented a control strategy for tablet manufacturing processes based on continuous direct compression.The work was conducted by the experts of pharmaceutical companies,machine suppliers,academia,and regulatory authority in Japan.Among different items in the process,the component ratio and blended powder content were selected as the items requiring the control method specific to continuous manufacturing different from the conventional batch manufacturing.The control and management of the Loss in Weight(LIW)feeder were deemed the most important,and the Residence Time Distribution(RTD)model were regarded effective for setting the control range and for controlling of the LIW feeder.Based on these ideas,the concept of process control using RTD was summarized.
基金National Key Research and Development Program of China(2016YFB0401702,2017YFE0120400)National Natural Science Foundation of China(61674074,61704170,61875082)+3 种基金Natural Science Foundation of Guangdong Province(2017B030306010)Guangdong University Key Laboratory for Advanced Quantum Dot Displays and Lighting(2017KSYS007)Shenzhen Peacock Team Project(KQTD2016030111203005)Development and Reform Commission of Shenzhen Project([2017]1395).
文摘Herein,we report the fabrication of high-performance transparent quantum-dot light-emitting diodes(Tr-QLEDs)with ZnO/ZnMgO inorganic double electron-transport layers(ETLs).The ETLs effectively suppress the excess electron injection and facilitate charge balance in the Tr-QLEDs.The thick ETLs as buffer layers can also withstand the plasma-induced damage during the indium tin oxide sputtering.These factors collectively contribute to the development of Tr-QLEDs with improved performance.As a result,our Tr-QLEDs with double ETLs exhibited a high transmittance of 82%at 550 nm and a record external quantum efficiency of 11.8%,which is 1.27 times higher than that of the devices with pure ZnO ETL.These results indicate that the developed ZnO/ZnMgO inorganic double ETLs could offer promising solutions for realizing high-efficiency Tr-QLEDs for next-generation display devices.
基金This work was carried out in the framework of the imec Core CMOS-Active Memory Program.T.R.acknowledges the support by Research Foundation-Flanders(FWO)for providing the funding via strategic basic research PhD fellowship(grant no.1SD4721).
文摘Restricted use of hazardous environmental chemicals is one important challenge that the semiconductor industry needs to face to improve its sustainability.Ovonic threshold switching(OTS)ternary compound materials used in memory selector devices contain As and Se.Engineering these elements out of these materials requires significant research effort.To facilitate this process,we performed systematic material screening for As/Se-free ternary materials,based on ab-initio simulations.To limit the large amount of possible chemical compositions to fewer promising candidates,we used physics-based material parameter filters like material stability,electronic properties,or change in polarizability.The OTS gauge concept is introduced as a computed parameter to estimate the probability of a material to show an OTS behavior.As a result,we identified 35 As/Se-free ternary alloy compositions for stand-alone OTS memory applications,as well as 12 compositions for RRAM selector applications.This work aims seeding the development of As/Se-free OTS materials.
基金supported by the Special Financial Support of Joint Building Project of the Beijing Education Committee
文摘In this study,a jet cavitation device aimed at producing two-dimensional nanosheets was designed.The effects of cavitation generator type and jet pressure on the cavitation inception and intensity were examined by monitoring the changes of sound pressure level(SPL).As such,the optimized cavitation generator with the best cavitation capability under the same ambient condition was determined.Further,BN and MoS 2,two kinds of layered materials,were exfoliated into individual flakes in aqueous solutions by this jet cavitation device.By investigating the morphology of these exfoliated flakes via scanning electron microscopy and transmission electron microscope,it was found that these pristine materials were mostly exfoliated into two-dimensional nanosheets,among which even monolayers were generally presented.This exfoliation process happened mainly due to the cavitation-induced intensive tensile stress acting on the layered materials.As graphene has been produced by this device successfully,it is anticipated that this jet cavitation device is suitable for producing other various two-dimensional nanosheets.
