The zinc (Zn) diffusion effects on metal–organic chemical vapor deposition grown flexible inverted metamorphic (IMM) GaInP/GaAs/InGaAs triple junction solar cell performance have been investigated. ...By studying electrical and spectral properties of solar cells with different configuration, it was found out that the Zn diffusion from GaAs middle cell AlGaAs:Zn back surface field (BSF) layer into AlGaAs/GaAs tunnel junction is the main reason for I–V curve inflection and low fill factor. Besides, the thermal annealing effects caused by the long epitaxial growth time also has significant effect on Zn diffusion and degrades the overall cell performance. These adverse effects caused by Zn diffusion was suppressed by replacing Zn with carbon as the p-type dopant source in BSF layer, and the thermal annealing effects was solved by fine tuning InGaAs bottom subcell base layer thickness. A large area, 4 × 2 cm2, flexible IMM GaInP/GaAs/InGaAs triple junction solar cell with 34.52% efficiency under AM 1.5D solar spectrum has been successfully fabricated.
•Zinc diffusion effects on GaInP/GaAs/InGaAs solar cell have been investigated.•Zn diffusion into tunnel junction is the reason for I–V curve inflection and low FF.•Prolonged epitaxial growth time enhances the Zn diffusion effect.•Zn diffusion effects was suppressed by using carbon as the p-type dopant source.•Cell efficiency increased by adjusting InGaAs bottom subcell base layer thickness.
Interactions between 3d transition-metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) and (5,5) carbon nanotube (CNT) with a vacancy defect are quantitatively characterized using first-principles ...calculations. The binding energies between CNT and transition metals are found to be significantly enhanced when vacancy defects are introduced into the CNT. For the defective CNTs doped with Sc, Cr and Zn atoms, the structures of defective CNTs are found to be intact. The doping of Ti, Mn, Cu, Fe, Ni and Co alternates the structures of defective CNTs. Among all 3d transition metals, only the ferromagnetic metal atoms Fe, Co and Ni form bonds with carbon atoms of CNT, suggesting the important role of magnetic exchange interaction in the p–d hybridisation between carbons and transition-metal atoms. The results also indicate that the 3d transition-metal atoms acting as substitutional defects can substantially modify the electronic structure of CNT. It is suggested that these stable CNT-metal systems could become promising engineering materials in many fields such as CNT devices for various spintronics applications and CNT metal–matrix composites.
The memory machine concept is recently extended to switched-flux (SF) machines, forming a series of SF hybrid magnet memory machines (SF-HMMMs). They exhibit the merits of good demagnetization ...withstand capability and effective flux adjustability. Nevertheless, the torque density is inevitably compromised due to the geometric conflict within the stationary part. Meanwhile, the inactivated dc coil, excluding online magnetization transients, results in system redundancy. Hence, in this paper, a new hybrid-excited (HE) concept is developed and implemented in a partitioned-stator SF-HPMM (PS-SF-HMMM). Thereby, the distinct synergies of a dual-magnet memory machine and an HE machine are achieved. With slight compensated field excitation, the torque can be improved at low-speed operation. Meanwhile, the high-speed constant-power region can be further extended without sacrificing high efficiency. The stator/rotor pole numbers are optimized first. The operating mechanism and optimal stepwise HE implementation over a whole operating envelop are then addressed. In addition, a comparison between PS-SF-HMMM with hybrid-excitation and its pure HE counterpart is established. Finally, both the finite-element simulation and experiments are carried out to verify the utility of the proposed HE concept.
In this paper, 1mm thick W-0.5wt%ZrC alloy plates were prepared by mechanical milling, hot pressing sintering and multistep hot and cold rolling. A newly developed testing technique based on the ...amplitude-dependent internal friction (ADIF) was used to determine the ductile-to-brittle transition temperature (DBTT) of this W-0.5wt%ZrC alloy. The DBTT obtained by ADIF technique is in the range of 50–80°C, which is in consistence with the tensile tests. Qualitative relationship between the critical strain amplitude in ADIF and the yield stress in tensile test was also found. The ADIF technique was confirmed to be an available method to determine the DBTT of the materials. Microstructure analysis indicated that the relative low DBTT and the high strength of the W-0.5wt%ZrC alloy plates were resulted from the multistep hot and cold rolling and nanoscale particle pinning effects.
Large-scale benchmark datasets are crucial in advancing research within the computer science communities. They enable the development of more sophisticated AI models and serve as "golden" benchmarks ...for evaluating their performance. Thus, ensuring the quality of these datasets is of utmost importance for academic research and the progress of AI systems. For the emerging vision-language tasks, some datasets have been created and frequently used, such as Flickr30k, COCO, and NoCaps, which typically contain a large number of images paired with their ground-truth textual descriptions. In this paper, an automatic method is proposed to assess the quality of large-scale benchmark datasets designed for vision-language tasks. In particular, a new cross-modal matching model is developed, which is capable of automatically scoring the textual descriptions of visual images. Subsequently, this model is employed to evaluate the quality of vision-language datasets by automatically assigning a score to each 'ground-truth' description for every image picture. With a good agreement between manual and automated scoring results on the datasets, our findings reveal significant disparities in the quality of the ground-truth descriptions included in the benchmark datasets. Even more surprising, it is evident that a small portion of the descriptions are unsuitable for serving as reliable ground-truth references. These discoveries emphasize the need for careful utilization of these publicly accessible benchmark databases.
Seasonal dormancy in deciduous fruit trees is a complex physiological state, which is regulated by many plant hormones and genes. Abscisic acid (ABA) and gibberellic acid (GA
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) are known to be ...particularly important in controlling dormancy. We measured the concentrations of these two hormones in flower buds (collected during para-, endo-, and eco-dormancy, and at the dormancy-release stage) and vegetative buds (collected monthly from 20 November 2012 to 20 February 2013) of two cultivars of Japanese apricot (Prunus mume Sieb. et Zucc), 'Bungo' and 'Taoxingmei', using liquid chromatography and tandem mass spectrometry (LC-MS/MS). Levels of expression of two zinc-finger family genes CCCH and C2H2 and the GA20ox (gibberellin 20 oxidase) gene (GenBank Accession No. Pm013607), as candidates for dormancy-controlling genes, were analysed at each sampling time using real-time RT-quantitative PCR (RT-qPCR). Expression analyses indicated that both zinc-finger family genes exhibited high transcript levels in flower buds of both cultivars during para-dormancy, concomitant with high ABA concentrations. The zinc-finger family genes were relatively highly expressed in vegetative buds of both cultivars on 20 November 2012 (autumn). In addition, high concentration of GA
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in flower buds at the dormancy-release stage suggested that GA
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plays an important role in controlling the release of bud dormancy. High levels of expression of the GA20ox gene during eco-dormancy and at the dormancy-release stage might have a prominent effect on dormancy-release by regulating gibberellin (GA) signalling in Japanese apricot. These results will contribute to increasing our understanding of ABA- and GA-mediated seasonal dormancy mechanisms in Japanese apricot.
The high-temperature stability and good mechanical strength of tungsten (W) alloys are highly desirable for a wide range of fusion applications, which can be achieved by dispersion strengthening. In ...this paper, TaC dispersion effects on the thermal stabilities, tensile properties and thermal shock resistances have been investigated. A hot-rolled W-1.0 wt% TaC plate has been fabricated which contains the high tensile strength and elongation. Nanosized particles in the W matrix improve the recrystallization temperature to about 1400 °C and the ultimate tensile strength to 571 MPa at 500 °C through hindering grain boundary migration, pinning dislocations and refining grains. The effects of edge-localized mode like transient heat events on the rolled and recrystallized W-1.0 wt% TaC alloys were investigated systematically. The cracking threshold (100 shots) at room temperature is in the range of 0.33–0.44 GW/m2 for the rolled W-1.0 wt% TaC. Recrystallization degrades mechanical strength and makes the material more prone to thermal shock damages. Coarse Ta2O5 and Ta-Cx-Oy particles are easy to fracture and introduce a preferential crack initiation in W matrix during cyclic heat loads.
Grading assignments is inherently subjective and time-consuming; automatic scoring tools can greatly reduce teacher workload and shorten the time needed for providing feedback to learners. The ...purpose of this paper is to propose a novel method for automatically scoring student responses to picture-cued writing tasks. As a popular paradigm for language instruction and assessment, a picture-cued writing task typically requires students to describe a picture or pictures. Correspondingly, the automatic scoring methods must measure the link(s) between visual pictures and their textual descriptions. For this purpose, we first designed a picture-cued writing test and collected nearly 4 k responses from 279 K12 students. Based on these responses, we then developed an AI scoring model by incorporating the emerging cross-modal matching technology and some NLP algorithms. The performance of the model was evaluated carefully with six popular measures and was found to demonstrate accurate scoring results with a small mean absolute error of 0.479 and a high adjacent-agreement rate of 90.64%. We believe this method could reduce the subjective elements inherent in human grading and save teachers’ time from the mundane task of grading to other valuable endeavors such as designing teaching plans based on AI-generated diagnosis of student progress.
Complete catalytic oxidation of toluene was investigated on Cu−Mn doped mesoporous and microporous catalysts, i.e., Cu−Mn/MCM-41, Cu−Mn/β-zeolite, Cu−Mn/ZSM-5 (where SiO2/Al2O3 is either 25 or 38), ...and Cu−Mn/porous silica, in the presence of excess oxygen. The result shows that mesoporous catalysts have exhibited the highest catalytic activity among these catalysts above. The less amount of coke formation due to the unique mesoporous structures could play a key role in the high activity on the mesoporous catalyst. In addition, the bimetallic Cu−Mn−MCM-41 supported catalyst shows higher oxidation activity than either single metal catalyst, i.e., Cu−MCM-41 and Mn−MCM-41. The highly dispersed Cu−Mn mixed oxides on mesoporous structures probably provide active sites for the complete oxidation of toluene on these mesoporous catalysts.
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