- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2019
- 2018
- 2015
- low-temperature electronics
- junction field-effect transistors
- Bessel Function
- Coupling Coefficient
- Fusion temperature and Elongation speed
- Infrared Thermography
- Statistical Analysis
- Mean Temperature Difference
- Surface temperature distribution
- Diabetic Foot Complications
- Optoelectronic Information Science and Engineering
- Electronic Science and Technology
- Physics
- Don State Technical University
- China Jiliang University
- UIN Suska Riau
- BMS College of Engineering
- Dalhousie University
- Majmaah University
- Soochow University
- University of Riau
- Karnataka Institute of Endocrinology and Research (KIER)
- Southern Federal University
-
Molecular dynamics simulation study on the structure and properties of polyimide/silica hybrid materials
摘要： A type of polyimide/silica (PI/SiO2) copolymer model was established through the dehydration of tetraethyl orthosilicate molecules (TEOS) and bonding to a silane coupling agent. The content of SiO2 was controlled by adjusting the number of molecules which bound to the TEOS. Finally, the silica was formed into a hybrid model (hybrid PI/SiO2) with a small molecule embedded in the PI. The model was optimized by geometric and molecular dynamics and the changes in the model structure, Young’s modulus, shear modulus, and glass-transition temperature (Tg) were analyzed. The results showed that the density and cohesive energy density of the composites could be improved by doping SiO2 in PI. Young’s modulus and shear modulus of PI/SiO2 hybrid materials were higher than undoped PI. The tensile strength reached 568.15 MPa when the doping content was 9%. Therefore, the structure design and content control of SiO2 was an effective way to improve the performance of a PI/SiO2 composite. The variation of Tg and tensile strength of PI/SiO2 hybrid composites is consistent with that of PI/SiO2 composite synthesized in real experiment, which will be a convenient method for new material design and performance prediction. ? 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 136, 47335.
关键词： molecular dynamics,shear modulus,Young’s modulus,polyimide/silica,glass-transition temperature
更新于2025-09-23 15:23:52
-
Extrinsic heavy metal atom effect on the solid state room temperature phosphorescence of cyclic triimidazole
摘要： Four coordination compounds [Zn3(CH3COO)6(H2O)2](TT)2, [Cd(H2O)6](ClO4)2(TT)2, [Cd(H2O)6](BF4)2(TT)2, [Zn(H2O)6](BF4)2(TT)2 (1-4) accommodating triimidazo[1,2-a:1',2'-c:1'',2''-e][1,3,5]triazine (TT) as a guest in their crystal lattice are isolated and fully photophysically and structurally characterized. Their emission properties are compared with those of afterglow TT and interpreted taking into account the heavy atom effect and crystal packing similarities and differences. In the case of 1, due to the closeness of the TT H-aggregates arrangement with that of the phosphor's pure phase, the observed intensification of the phosphorescent emission at the expense of the prompt one is attributed to the extrinsic heavy atom effect of Zn. In 2 and 3, the heavier Cd atom is responsible for a decrease in the lifetimes of the afterglow emission, despite the presence of tightly overlapped H-dimers in the crystal structure. Finally for 4, isostructural with 3, the Zn atom reveals in RTUP lifetime comparable with that of 1.
关键词： extrinsic heavy atom effect,H aggregates,time resolved photoluminescence,room temperature ultralong phosphorescence,single crystal XRD
更新于2025-09-23 15:23:52
-
Polymorphic Pure Organic Luminogens with Through Space Conjugation and Persistent Room Temperature Phosphorescence
摘要： Pure organic luminogens with persistent room temperature phosphorescence (p-RTP) have attracted increasing attention owing to their fundamental significance and potential applications in security inks, bioimaging, and photodynamic therapy. Previous p-RTP luminogens are normally with through bond conjugation. In this work, we report a pure organic luminogen, AN-MA, the Diels-Alder cycloaddition adduct of anthracene (AN) and maleic anhydride (MA), which possesses isolated phenyls and anhydride moiety. AN-MA exhibits aggregation-enhanced emission (AEE) characteristics, with efficiency of ~2% and up to 8.5% in solution and crystals, respectively. Two polymorphs of AN-MA are readily obtained, which can generate UV emission from individual phenyl rings together with bright blue emission owing to the effective through space conjugation. Moreover, p-RTP with lifetime of up to ~1.6 s is obtained in crystals. These results not only disclose a new system with both fluorescence and RTP dual emission, but also suggest an alternative through space conjugation strategy towards pure organic p-RTP luminogens with tunable emissions.
关键词： anticounterfeiting,pure organic luminogens,persistent room temperature phosphorescence,through space conjugation,polymorphism
更新于2025-09-23 15:23:52
-
Normally-off AlGaN/GaN Heterojunction Metal-Insulator-Semiconductor Field-Effect Transistors with Gate-First Process
摘要： In this study, AlGaN/GaN heterojunction metal-insulator-semiconductor field-effect transistors with gate-first process were developed for normally-off operation with p-GaN cap layers and SiNx dielectrics. To avoid the effect of the annealing process on the gate, a low-temperature ohmic contact technique was developed at an annealing temperature of about 500 oC for 20 min in N2 ambient. With the assistance of inductively coupled plasma dry etching, a contact resistance of 1.45 Ω·mm and sheet resistance of 1080.1 Ω/□ were obtained in the recessed region. Owing to the inset of the SiNx layer, the threshold voltage of fabricated device was enhanced to approximately 2 V, and good pinch-off was observed with the gate voltage up to 16 V. Compared with the conventional high-temperature ohmic annealing process, the gate leakage current was suppressed significantly in both reverse and forward directions. Good device performance was confirmed with a maximum channel electron field-effect mobility of 1500 cm2V-1s-1.
关键词： low-temperature ohmic contact,normally-off,gate-first,metal-insulator-semiconductor,AlGaN/GaN HFET
更新于2025-09-23 15:23:52
-
[ACM Press the 3rd International Conference - Tetouan, Morocco (2018.10.10-2018.10.11)] Proceedings of the 3rd International Conference on Smart City Applications - SCA '18 - Empirical models for estimating the global solar radiation based on air temperature and sunshine duration
摘要： This work aims to develop and validate empirical models for estimating global solar radiation at site of Alhoceima based on the meteorological data measured during the period 2010-2017. The empirical models studied in this paper are broken down into two categories: the first category consist of linear and nonlinear regression which relates the monthly average daily global solar radiation to the sunshine duration, such as: the model of Angstr?m-Prescott, the cubic, quadratic model (Ogleman et al.), exponential (Almorox), logarithmic and power model. The second category consists of mathematical models calculating the monthly average daily global solar radiation based on the air temperature. And finally this study proposed model wish is based on sunshine duration and gives the best results for the city of Alhoceima. Statistical evaluation of the performance and accuracy of the models on the basis of The Root Mean Square Error (RMSE), Mean Bias Error MBE and R2 coefficient of determination, showed that all calibrated models estimates very well the monthly average daily global radiation. However the proposed model is more accurate with smaller errors and the best coefficient of determination.
关键词： air temperature,empirical model,sunshine duration,Daily global solar radiation,estimating global solar radiation
更新于2025-09-23 15:23:52
-
Temperature-Dependent Electrical Characteristics of β-Ga <sub/>2</sub> O <sub/>3</sub> Diodes with W Schottky Contacts up to 500°C
摘要： The development of thermally stable contacts capable of high temperature operation are necessary for Ga2O3 high power rectifiers. We have measured the electrical characteristics of sputter-deposited W Schottky contacts with Au overlayers for reducing sheet resistance on n-type Ga2O3 before and after device operation up to 500°C. Assuming thermionic emission is dominant, the extracted barrier height decreases with measurement temperature from 0.97 eV (25°C) to 0.39 eV (500°C) while showing little change from its initial value of 0.97 eV after cooling down from each respective operation temperature. The room temperature value is comparable to that obtained by determining the energy difference between binding energy of the Ga 3d core level and the valence band of the Ga2O3 when W is present, 0.80 ± 0.2 eV in this case. The Richardson constant was 54.05 A.cm?2.K?2 for W and the effective Schottky barrier height at zero bias (eφb0) was 0.92 eV from temperature-dependent current-voltage characteristics. The temperature coefficient for reverse breakdown voltage was 0.16 V/K for W/Au and 0.12 V/K for Ni/Au. The W-based contacts are more thermally stable than conventional Ni-based Schottkies on Ga2O3 but do show evidence of Ga migration through the contact after 500°C device operation.
关键词： electrical characteristics,thermal stability,high temperature operation,Ga2O3,Schottky contacts
更新于2025-09-23 15:23:52
-
[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - The Effect of Trunks on Directional Brightness Temperatures of a Leafless Forest Using a Geometrical Optical Model
摘要： In the paper, a geometric optical model is proposed for a vegetation-trunk-soil scene. The effect of tree trunks was analyzed by comparing directional brightness temperatures (BTs) between vegetation-soil and vegetation-trunk-soil scenes. The comparison result reveals the tree trunk can cause directional BTs as a whole lower because of its shadow and shaded area. Therefore, the tree trunk should be considered when retrieving temperatures from thermal infrared observations over a leafless forest. Efforts using measured TIR data requires to be done in the future.
关键词： vegetation-trunk-soil canopy,directional anisotropy,brightness temperature
更新于2025-09-23 15:23:52
-
[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Imaging Spectrometry and Fluorometry in Support of Flex: What Can We Learn from Multi-Scale Experiments?
摘要： In advance of the FLEX mission, experimental studies are needed to better understand the factors driving Solar-Induced Fluorescence (SIF) emission from vegetation across different temporal and spatial scales. Here, we present findings from boreal (evergreen and deciduous) forest trees and Midwestern (annual) crops, illustrating effects of seasonal downregulation and drought on the fluorescence signals. Further work is needed to develop defensible, quantitative fluorescence measurements, and to partition the drivers of the fluorescence signals into effects of structure and physiology.
关键词： chlorophyll fluorescence (SIF, Fs),stress,photosynthesis,drought,temperature,chlorophyll/carotenoid pigments
更新于2025-09-23 15:23:52
-
Scattering Effect Contributions to the Directional Canopy Emissivity and Brightness Temperature Based on CE-P and CBT-P Models
摘要： The directional anisotropy of canopy emissivity and brightness temperature in the thermal infrared band has widely been studied. However, the contribution of different scattering orders has been an open scientific question for many years. The recently proposed CE-P model enables us to analytically evaluate the different scattering orders. Herein, we derive expressions for the first double collisions (DCE12) and first triple collisions (DCE123). Our result shows that DCE123 can simulate the observed emissivity with an error less than 0.001 and that DCE12 is reasonably accurate when leaf emissivity is greater than 0.96. Numerical analysis shows that the contribution of quadruple or greater collisions can be ignored when the leaf (soil) emissivity is no less than 0.90. Furthermore, we develop the CBT-P model to simulate the directional brightness temperature (DBT) based on the new optimized CE-P model (DCE123) and validate it by 4SAIL (4-Stream Radiative Transfer Theory of Scattering by Arbitrary Inclined Leaves) and DART (Discrete Anisotropic Radiative Transfer) models. Both of isothermal (soil temperature is equal to leaf temperature) and nonisothermal (soil temperature is higher than leaf temperature) cases are considered. The maximum differences between the CBT-P model and 4SAIL (DART) are less than 0.35 K (0.42 K), the average differences between CBT-P and 4SAIL (DART) are less than 0.10 K (0.13 K), and the R2 is over 0.99 (0.95) with component emissivities larger than 0.90 and the difference between soil and leaf temperatures less than 20 K. The directional anisotropy of DBT is dominated by the zero-scattering and the single scattering terms according to the new developed CBT-P model.
关键词： directional canopy emissivity (DCE),CBT-P,Discrete Anisotropic Radiative Transfer (DART),4-Stream Radiative Transfer Theory of Scattering by Arbitrary Inclined Leaves (4SAIL),CE-P,directional brightness temperature (DBT)
更新于2025-09-23 15:23:52
-
Design of High Temperature Superconducting Dual-Band Filter with Multiple Transmission Zeros
摘要： A multi-order dual-band high temperature superconducting (HTS) bandpass filter (BPF) with multiple transmission zeros (TZs) is designed in this paper. The theoretical characteristics of the introduction of TZs by the electric and magnetic mixed coupling, and the cascade quadruplet (CQ) cross-coupling structures are analyzed, respectively. These two methods can be applied to the design of the multi-mode compact dual-band HTS BPF with controllable central frequency, bandwidth and TZs. For demonstration, a Y-shape tunable resonator structure which can simultaneously implement the internal electric and magnetic mixed coupling, and the external cross coupling is constructed to achieve the proposed dual-band BPF. The external quality factors required by the two passbands and the feasibility of independently adjusting the coupling strength between adjacent resonators are analyzed. Finally, a 6-order dual-band HTS BPF with the center frequencies of 1490MHz (bandwidth of 40 MHz) and 2340MHz (bandwidth of 80 MHz) is designed and fabricated on the double-sided YBCO/MgO/YBCO HTS thin films with the size of 17.2mm×14.7mm (0.20λg × 0.17λg), and there are multiple of TZs located outside the two passbands, respectively. The out-of-band rejections are greatly improved to 70dB and 80dB due to these TZs, which fully exhibits the advantages of the proposed dual-band BPF. The measured results are in good agreement with the simulated ones.
关键词： high temperature superconducting (HTS),Dual-band,passband filter,transmission zero (TZ),cascade quadruplet (CQ)
更新于2025-09-23 15:23:52