6,642 research outputs found
Native p-type transparent conductive CuI via intrinsic defects
No full textThe ability of CuI to be doped p-type via the introduction of native defects has been investigated using first-principles pseudopotential calculations based on density functional theory. The Cu vacancy has a lower formation energy than any of the other native defects, which include I vacancy (V(I)), Cu interstitial (Cu(i)), I interstitial (I(i)), Cu antisite (Cu(I)), and I antisite (I(Cu)). Combined with its shallow acceptor level, it offers sufficient hole concentrations in CuI. The natural band alignments as compared to zinc-blende ZnS, ZnSe, and ZnTe have also been calculated in order to further identify the p-type dopability of CuI. It is found that CuI has a relatively high valence band maximum and conduction band minimum, which also makes it easy to dope CuI p-type in terms of the doping limit rule. In addition, the small effective mass of the light hole-about 0.303m(0)-can provide high mobility and p-type conductivity in CuI. All of these results make CuI an ideal candidate for native p-type materials (C) 2011 American Institute of Physics. [doi:10.1063/1.3633220
Youthhood
No full textTESTING-GROUND issue 03, Youthhood, examines worlds through youthful eyes, makes evident young ambitions, and questions how we can better empower young people to design cities, landscapes, and a planet that works for them. The issue includes contributions from: Carmel Keren, Jude Daniel Smith, Claire Edwards, Kazeem Kuteyi, Emmanuel Adarkwah, Reza Nik, Dan Cui, Kristofer Cullum-Fernandez, Fida Sassi, Simeon Shtebunaev, Daze Aghaji, Averill Dimabuyu, Sarri Elfaitouri, Rebecca McDonald-Balfour, and Ed Wall.
Rebecca McDonald-Balfour (Author), Jude Daniel Smith (Author), Daze Aghaji (Author), Carmel Keran (Author), Alexis Liu (Author), Dan Cui (Author), Kristofer Cullum-Fernandez (Author), Fida Sassi (Author), Averill Dimabuyu (Author), Ed
Impact damage of composite laminates with high-speed waterjet
No full textRain erosion may cause substantial damage to aircrafts during supersonic flight. Such event is investigated here via high-speed waterjet impact on composite laminates. An experimental setup is developed to produce waterjets with the speed up to 700m/s and a finite element model of the waterjet-composite impact event is established. The consistency of experiment and simulation results validates the adopted numerical methods. The distribution of the water-hammer pressure is non-uniform and the maximum pressure occurs near the contact periphery when the water is about to eject laterally. After a high-speed (300∼560m/s) waterjet impacts a composite laminate, the impacted surface depression is observed, and the typical surface damage presents a central region with no visible surface damage surrounded by a faded “failure ring” with resin removal, matrix cracking and minor fiber fracture. Delamination occurs at the interfaces of adjacent layers with unequal dimensions and longitudinal matrix cracking appears on the back surface. Both the velocity and the diameter of waterjets are crucial factors on CFRP damage extents. Water-hammer pressure, the stagnation pressure and propagation of stress waves are failure mechanisms for most matrix damage in CFRP impacted by waterjets.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite
Sampling and Reconstruction of Signals on Product Graphs
No full textIn this paper, we consider the problem of subsampling and reconstruction of signals that reside on the vertices of a product graph, such as sensor network time series, genomic signals, or product ratings in a social network. Specifically, we leverage the product structure of the underlying domain and sample nodes from the graph factors. The proposed scheme is particularly useful for processing signals on large-scale product graphs. The sampling sets are designed using a low-complexity greedy algorithm and can be proven to be near-optimal. To illustrate the developed theory, numerical experiments based on real datasets are provided for sampling 3D dynamic point clouds and for active learning in recommender systems.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Signal Processing System
Ban dao ti yi zhi jie gou zai guang cui hua he guang dian cui hua zhong de yan jiu
No full textLi, Qian = 半導體异质结构在光催化和光電催化中的研究 / 李乾.Thesis Ph.D. Chinese University of Hong Kong 2015.Includes bibliographical references (leaves 145-162).Abstracts also in Chinese.Title from PDF title page (viewed on 30, December, 2016).Li, Qian = Ban dao ti yi zhi jie gou zai guang cui hua he guang dian cui hua zhong de yan jiu / Li Qian
A Conversational User Interface for Instructional Maintenance Reports
No full textMaintaining a complex system, such as a modern production line, is a knowledge-intensive task. Many firms use maintenance reports as a decision support tool. However, reports are often poor quality and tedious to compile. A Conversational User Interface (CUI) could streamline the reporting process by validating the user's input, eliciting more valuable information, and reducing the time needed. In this paper, we use a Technology Probe to explore the potential of a CUI to create instructional maintenance reports. We conducted a between-groups study (N = 24) in which participants had to replace the inner tube of a bicycle tire. One group documented the procedure using a CUI while replacing the inner tube, whereas the other group compiled a paper report afterward. The CUI was enacted by a researcher according to a set of rules. Our results indicate that using a CUI for maintenance reports saves a significant amount of time, is no more cognitively demanding than writing a report, and results in maintenance reports of higher quality. Internet of ThingsHuman-Centred Artificial Intelligenc
The Logic of Knowledge-Based Cooperation in the Social Dilemma
No full textComputer Science, Artificial IntelligenceComputer Science, Theory & MethodsCPCI-S(ISTP)
Natural CO2 leakage and responses of shallow aquifers in the southern Xining Basin
No full textObjective Geological storage of CO2 is an important technology for reducing CO2 emissions, and the assessment of CO2 leakage risk is the key to its implementation. Research on natural CO2 leakage is an important means to obtain key information for leakage assessment. Methods The source of CO2, the characteristics of CO2 leakage, and the relevant response of shallow aquifers to the CO2 leakage have been analysed through field investigations, on-site measurements, and sampling and testing of water, gas and rock. Results A number of natural CO2 leakages have been discovered in the southern Xining Basin, including CO2-rich springs, CO2-driven cold-water geysers from abandoned wells, and CO2 blowouts, as well as large-scale travertine associated with them. CO2 is the dominant component in the gas phase, and the abundance of carbon isotope of CO2 is between -2.5‰ and -0.4‰, indicating that the leaked CO2 comes from a deep inorganic origin, leaks into shallow confined aquifers through deep faults, and flows and discharges with the groundwater or accumulates secondarily in shallow formations. The concentration of soil 222Rn in areas of CO2 leakage is abnormal (over 9 000 Bq/m3), which can be used as an important method of identifying hidden leakage channels. The groundwater has a pronounced response to CO2 leakage, including a unique phenomenon of intermittent eruptions (eruption for 200 s and incubation for 130 s), changes in groundwater hydrochemical characteristics (e.g., a decrease in pH, an increase in conductance and HCO3- and Ca2+ concentrations, and a drift in oxygen isotopes), and travertine composed mainly of calcite with a bubble structure at the surface. The natural CO2 leakage characteristics at this site are highly similar to those in Utah, USA. Conclusion The results of this study not only provide knowledge of natural analogous for leakage risk assessment of CO2 geological storage, but also contribute to the understanding of geological activity in the deep earth
CUHK electronic theses & dissertations collection
No full textCui, Yan.Thesis Ph.D. Chinese University of Hong Kong 2015.Includes bibliographical references (leaves 236-251).Abstracts also in Chinese.Title from PDF title page (viewed on 15, September, 2016)
Spatiotemporal differentiation of the ecosystem service value and its coupling relationship with urbanization: A case study of the Lanzhou-Xining urban agglomeration
No full textUrbanization is a key factor that threatens the stability of ecosystem services (ESs), which are crucial for maintaining ecological security and enhancing human quality of life. Gaining insight into the spatiotemporal differentiation of the ecosystem service value (ESV) and its coupling relationship with urbanization is a key issue in promoting sustainable regional development. We employed various algorithms, including the improved equivalence factor method, random forest model, mixed geographically and temporally weighted regression model, and coupling coordination degree (CCD) model, to reveal the spatiotemporal evolution of the ESV and its driving mechanisms in the Lanzhou-Xining urban agglomeration (LXUA) from 1980 to 2020. In addition, we explored the coupling relationship between ESV and the combined urbanization index (CUI). The results showed the following: (1) From 1980 to 2020, the interannual variation in ESV first decreased and then increased, with an increase of 230 million yuan/annum in 2020 compared to that of 1980. Spatially, the ESV exhibits a distribution pattern of high in the south and low in the north, and high in the west and low in the east. (2) Land use intensity (LUI) and elevation contributed degree values exceeding 20% to the ESV and were the most important drivers of the ESV. (3) From 1980 to 2020, the average CCD values of the ESV and CUI transitioned from being severely unbalanced (0.19) to being slightly balanced (0.42). There was a negative spatial correlation between the ESV and CUI, with each cluster type was distributed discretely in space. Our study emphasizes that in areas characterized by robust ecosystem integrity and a high ESV, the increase in LUI was constitutes the main reason for the decline in the ESV. The findings of this study can provide a scientific basis for the coordinated development of ESVs and urbanization in the LXUA and other cities
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