A numerical model for bilayer organic light-emitting diodes (OLEDs) is developed under the basis of trapped charge limited conduction.The dependences of the current density on the layer thickness,trap properties and c...A numerical model for bilayer organic light-emitting diodes (OLEDs) is developed under the basis of trapped charge limited conduction.The dependences of the current density on the layer thickness,trap properties and carrier mobility of the hole transport layer (HTL) and emission layer (EML) in bilayer OLEDs of the structure anode/HTL/EML/cathode are numerically investigated.It is found that,for given values of the total thickness of organic layers,reduced depth of trap,total density of trap,and carrier mobility of HTL as well as EML,there exists an optimal thickness ratio of HTL to EML,by which a maximal quantum efficiency can be achieved.Through optimization of the thickness ratio,an enhancement of current density and quantum efficiency of as much as two orders of magnitude can be obtained.The dependences of the optimal thickness ratio to the characteristic trap energy,total density of trap and carrier mobility are numerically analyzed.展开更多
A compact drain current including the variation of barrier heights and carrier quantization in ultrathin-body and double-gate Schottky barrier MOSFETs （UTBDG SBFETs） is developed. In this model, Schrodinger＇s equat...A compact drain current including the variation of barrier heights and carrier quantization in ultrathin-body and double-gate Schottky barrier MOSFETs （UTBDG SBFETs） is developed. In this model, Schrodinger＇s equation is solved using the triangular potential well approximation. The carrier density thus obtained is included in the space charge density to obtain quantum carrier confinement effects in the modeling of thin-body devices. Due to the quantum effects, the first subband is higher than the conduction band edge, which is equivalent to the band gap widening. Thus, the barrier heights at the source and drain increase and the carrier concentration decreases as the drain current decreases. The drawback of the existing models,which cannot present an accurate prediction of the drain current because they mainly consider the effects of Schottky barrier lowering （SBL） due to image forces,is eliminated. Our research results suggest that for small nonnegative Schottky barrier （SB） heights,even for zero barrier height, the tunneling current also plays a role in the total on-state currents. Verification of the present model was carried out by the device numerical simulator-Silvaco and showed good agreement.展开更多
Based on the properties of ordered weighted averaging (OWA) operator and regular increasing monotone (RIM) quantifier, three methods for generating monotonic OWA operator weights are proposed. They are geometric OWA o...Based on the properties of ordered weighted averaging (OWA) operator and regular increasing monotone (RIM) quantifier, three methods for generating monotonic OWA operator weights are proposed. They are geometric OWA operator weights, equidifferent OWA operator weights and the modified RIM quantifier OWA weights. Compared with most of the common OWA methods for generating weights, the methods proposed in this paper are more intuitive and efficient in computation. And as there are more than one solution in most cases, the decision maker can set some initial condition and chooses the appropriate solution in the real decision process, which increases the flexibility of decision making to some extent. All these three OWA methods for generating weights are illustrated by numerical examples.展开更多
The intake swirl in the cylinder was induced by a swirler which was fixed in one of two intake ports. In order to understand the characteristics of the intake swirl, a transparent water analog was designed which simul...The intake swirl in the cylinder was induced by a swirler which was fixed in one of two intake ports. In order to understand the characteristics of the intake swirl, a transparent water analog was designed which simulated 150 type single cylinder engine. At the same time, the particle image velocimetry was used to measure the flow fields induced by various swirlers in the analog. After measurement, a new method was presented to evaluate the intensity of the intake swirl. Then, when the measured sections, the lifts of valve and the swirlers were different, the calculated results of the flow field were compared.展开更多
The growth characteristics during metalorganic chemical vapor deposition and optical properties of ZnO films on sapphire （Al2O3） （0001） and （1120） substrates are studied. For the former,the effects of two import...The growth characteristics during metalorganic chemical vapor deposition and optical properties of ZnO films on sapphire （Al2O3） （0001） and （1120） substrates are studied. For the former,the effects of two important growth parameters,i, e. temperature and pressure, are investigated in detail. Due to the large lattice mismatch between the film and the substrate, ZnO nanocrystals are usually obtained. The growth behavior at the film-substrate interface is found to be strongly dependent on the growth temperature,while the growth pressure determines the shape of the nanostructures as they grow. It is difficult to obtain ZnO films that have good quality and a smooth surface simultaneously. Due to the smaller lattice mismatch,the critical thickness of ZnO on the Al2O3 （1120） surface is found to be much larger than that on the Al2O3 （0001） surface. ZnO/MgZnO quantum wells with graded well thicknesses are grown on the Al2O3 （1120） surfaces,and their optical properties are studied. The built-in electric field in the well layer, generated by the piezoelectric effect, is estimated to be 3 × 10^5 V/cm. It is found that growth at low temperatures and low pressures may facilitate the incorporation of acceptor impurities in ZnO.展开更多
The aim of the study is to investigate the contents of trace element Se, Cd, Pb in three plants including burdock, ginkgol and garlic via graphite furnace atomic absorption and standard addition method. The results sh...The aim of the study is to investigate the contents of trace element Se, Cd, Pb in three plants including burdock, ginkgol and garlic via graphite furnace atomic absorption and standard addition method. The results show that Se in burdock stem, skin and leaf are 32.40, 48.63, 38.10 μg/g, respectively; Cd in burdock stem, skin and leaf are 0. 160 0, 0. 300 0, 0. 140 0 μg/g, respectively; Cd in burdock stem, skin and leaf are 2. 020, 3. 960, 2. 410 μg/g, respectively. In the ginkgo and ginko leaf, Se contents are 17.63 and 16.91 μg/g, respectively ; for Cd are 0. 181 0 and 0.2020μg/g, respectively ; for Pb are 3. 572 and 4. 021 μg/g, respectively. In garlic, Se, Cd and Pb are 73. 900 0, 6. 900 0 and 0. 390 0, respectively. All the standard deviations of measured results are below 2.3%, recovery rate are from 99% to 101%.展开更多
文摘A numerical model for bilayer organic light-emitting diodes (OLEDs) is developed under the basis of trapped charge limited conduction.The dependences of the current density on the layer thickness,trap properties and carrier mobility of the hole transport layer (HTL) and emission layer (EML) in bilayer OLEDs of the structure anode/HTL/EML/cathode are numerically investigated.It is found that,for given values of the total thickness of organic layers,reduced depth of trap,total density of trap,and carrier mobility of HTL as well as EML,there exists an optimal thickness ratio of HTL to EML,by which a maximal quantum efficiency can be achieved.Through optimization of the thickness ratio,an enhancement of current density and quantum efficiency of as much as two orders of magnitude can be obtained.The dependences of the optimal thickness ratio to the characteristic trap energy,total density of trap and carrier mobility are numerically analyzed.
文摘A compact drain current including the variation of barrier heights and carrier quantization in ultrathin-body and double-gate Schottky barrier MOSFETs （UTBDG SBFETs） is developed. In this model, Schrodinger＇s equation is solved using the triangular potential well approximation. The carrier density thus obtained is included in the space charge density to obtain quantum carrier confinement effects in the modeling of thin-body devices. Due to the quantum effects, the first subband is higher than the conduction band edge, which is equivalent to the band gap widening. Thus, the barrier heights at the source and drain increase and the carrier concentration decreases as the drain current decreases. The drawback of the existing models,which cannot present an accurate prediction of the drain current because they mainly consider the effects of Schottky barrier lowering （SBL） due to image forces,is eliminated. Our research results suggest that for small nonnegative Schottky barrier （SB） heights,even for zero barrier height, the tunneling current also plays a role in the total on-state currents. Verification of the present model was carried out by the device numerical simulator-Silvaco and showed good agreement.
文摘Based on the properties of ordered weighted averaging (OWA) operator and regular increasing monotone (RIM) quantifier, three methods for generating monotonic OWA operator weights are proposed. They are geometric OWA operator weights, equidifferent OWA operator weights and the modified RIM quantifier OWA weights. Compared with most of the common OWA methods for generating weights, the methods proposed in this paper are more intuitive and efficient in computation. And as there are more than one solution in most cases, the decision maker can set some initial condition and chooses the appropriate solution in the real decision process, which increases the flexibility of decision making to some extent. All these three OWA methods for generating weights are illustrated by numerical examples.
文摘The intake swirl in the cylinder was induced by a swirler which was fixed in one of two intake ports. In order to understand the characteristics of the intake swirl, a transparent water analog was designed which simulated 150 type single cylinder engine. At the same time, the particle image velocimetry was used to measure the flow fields induced by various swirlers in the analog. After measurement, a new method was presented to evaluate the intensity of the intake swirl. Then, when the measured sections, the lifts of valve and the swirlers were different, the calculated results of the flow field were compared.
文摘The growth characteristics during metalorganic chemical vapor deposition and optical properties of ZnO films on sapphire （Al2O3） （0001） and （1120） substrates are studied. For the former,the effects of two important growth parameters,i, e. temperature and pressure, are investigated in detail. Due to the large lattice mismatch between the film and the substrate, ZnO nanocrystals are usually obtained. The growth behavior at the film-substrate interface is found to be strongly dependent on the growth temperature,while the growth pressure determines the shape of the nanostructures as they grow. It is difficult to obtain ZnO films that have good quality and a smooth surface simultaneously. Due to the smaller lattice mismatch,the critical thickness of ZnO on the Al2O3 （1120） surface is found to be much larger than that on the Al2O3 （0001） surface. ZnO/MgZnO quantum wells with graded well thicknesses are grown on the Al2O3 （1120） surfaces,and their optical properties are studied. The built-in electric field in the well layer, generated by the piezoelectric effect, is estimated to be 3 × 10^5 V/cm. It is found that growth at low temperatures and low pressures may facilitate the incorporation of acceptor impurities in ZnO.
基金School Fund of Xuzhou Institute of Technology (XKY200614)~~
文摘The aim of the study is to investigate the contents of trace element Se, Cd, Pb in three plants including burdock, ginkgol and garlic via graphite furnace atomic absorption and standard addition method. The results show that Se in burdock stem, skin and leaf are 32.40, 48.63, 38.10 μg/g, respectively; Cd in burdock stem, skin and leaf are 0. 160 0, 0. 300 0, 0. 140 0 μg/g, respectively; Cd in burdock stem, skin and leaf are 2. 020, 3. 960, 2. 410 μg/g, respectively. In the ginkgo and ginko leaf, Se contents are 17.63 and 16.91 μg/g, respectively ; for Cd are 0. 181 0 and 0.2020μg/g, respectively ; for Pb are 3. 572 and 4. 021 μg/g, respectively. In garlic, Se, Cd and Pb are 73. 900 0, 6. 900 0 and 0. 390 0, respectively. All the standard deviations of measured results are below 2.3%, recovery rate are from 99% to 101%.
