6,879 research outputs found
Replication Data for: Impacts of Rates of Change in Effective Stress and of Inertial Effects on Fault Slip Behavior: New Insights into Injection-induced Earthquakes
No full textReplication Data for: Impacts of Rates of Change in Effective Stress and of Inertial Effects on Fault Slip Behavior: New Insights into Injection-induced Earthquake
Pilot-scale treatment of pharmaceutical berberine wastewater by Fenton oxidation
No full textFenton oxidation was used to treat the berberine finished mother liquor wastewater in pilot scale. To evaluate berberine and COD removal efficiency, the main factors, including pH, H2O2 dosage, Fe2+/H2O2 mass ratio and the water flow (Q), were optimized using response surface methodology (RSM). The results showed that under the optimal conditions, pH 3, H2O2/COD molar ratio of 1.25, Fe2+/H2O2 molar ratio of 0.1, Q 100 L/h [with hydraulic retention time (HRT) of 2.5 h], the COD and berberine removal efficiencies were 35.6 and 91.4 % at initial COD concentration of 4061 mg/L and berberine concentration of 709 mg/L, respectively. The (BOD5)/(COD) ratio (B/C) of the wastewater increased from 0 to 0.3, indicating significantly improved biodegradability of wastewater
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
Exploring Advanced Polymeric Binders and Solid Electrolytes for Energy Storage Devices
No full textIntermittent electricity generation from renewable energy sources, such as wind energy, ocean energy, and solar energy, has significantly intensified the demand for high-energy-density, high-power, and low-cost energy storage devices. In this regard, tremendous efforts have been devoted to the development of electrode materials, electrolytes, and separators of energy-storage devices to address the fundamental needs of emerging technologies such as electric vehicles, artificial intelligence, and virtual reality. Polymer materials are ubiquitous in fabricating these energy storage devices and are widely used as binders, electrolytes, separators, and other components. However, binders, as an important component in energy-storage devices, are yet to receive sufficient attention. Polyvinylidene fluoride (PVDF) has been the dominant binder in the battery industry for decades despite several well-recognized drawbacks, i.e., limited binding strength due to the lack of chemical bonds with electroactive materials, insufficient mechanical properties, and low electronic and lithium-ion conductivities. The limited binding function cannot meet the inherent demands of emerging electrode materials with high capacities such as silicon anodes and sulfur cathodes. Polymers are also used as electrolyte matrices because they offer the advantages of low cost, lightweight, easy processability, excellent mechanical deformation, and better interfacial contact and compatibility with electrodes. However, the practical implementation of solid polymer electrolytes has been hindered by several challenging issues including low ionic conductivity, low ion transfer number, high-voltage instability, and lithium dendrite growth. Because of the increasingly growing demand for higher performance of energy storage devices, it is necessary to develop novel polymeric binders and solid electrolytes with advanced functionalities to help improve the operation of the currently existing energy storage systems.
In the first study, we synthesized a novel self-healing poly(ether-thioureas) (SHPET) polymer with balanced rigidity and softness for the silicon anode. The as-prepared silicon anode with the self-healing binder exhibits excellent structural stability and superior electrochemical performance, delivering a high discharge capacity of 3744 mAh g−1 at a current density of 420 mA g−1, and achieving a stable cycle life with a high capacity retention of 85.6% after 250 cycles at a high current rate of 4200 mA g−1. The success of this work suggests that the proposed SHPET binder facilitates fast self-healing, buffers the drastic volume changes and overcomes the mechanical strain in the course of the charge/discharge process, and could subsequently accelerate the commercialization of the silicon anode.
Binders could play crucial or even decisive roles in the fabrication of low-cost, stable, and high-capacity electrodes. This is especially the case for the silicon (Si) anodes and sulfur (S) cathodes that undergo large volume change and active material loss in lithium-ion batteries during prolonged cycles. In the second study, a hydrophilic polymer poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) was explored as a dual-functional aqueous binder for the preparation of high-performance silicon anodes and sulfur cathodes. Benefiting from the dual functions of PMVEMA, i.e., the excellent dispersion ability and strong binding forces, the as-prepared electrodes exhibit improved capacity, rate capability, and long-term cycling performance. In particular, the as-prepared Si electrode delivers a high initial discharge capacity of 1346.5 mAh g-1 at a high rate of 8.4 A g-1 and maintains 834.5 mAh g-1 after 300 cycles at 4.2 A g-1, while the as-prepared S cathode exhibits enhanced cycling performance with high remaining discharge capacities of 711.44 mAh g-1 after 60 cycles at 0.2 C and 487.07 mAh g-1 after 300 cycles at 1 C, respectively. These encouraging results suggest that PMVEMA could be a universal binder to facilitate the green manufacture of both anodes and cathodes for high-capacity energy storage systems.
Stable and seamless interfaces among solid components in all‐solid‐state batteries (ASSBs) are crucial for high ionic conductivity and high rate performance. This can be achieved by the combination of functional inorganic material and flexible polymer solid electrolytes. In the third study, a flexible all‐solid‐state composite electrolyte is synthesized based on oxygen‐vacancy‐rich Ca‐doped CeO2 (Ca-CeO2) nanotube, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and poly(ethylene oxide) (PEO), namely Ca-CeO2/LiTFSI/PEO. Ca-CeO2 nanotubes play a key role in enhancing ionic conductivity and mechanical strength while the PEO offers flexibility and assures the stable seamless contact between the solid electrolyte and the electrodes in ASSBs. The as‐prepared electrolyte exhibits high ionic conductivity of 1.3 × 10−4 S cm−1 at 60 °C, a high lithium ion transference number of 0.453, and high‐voltage stability. More importantly, various electrochemical characterizations and density functional theory (DFT) calculations reveal that Ca-CeO2 helps dissociate LiTFSI, produces free Li-ions, and therefore enhances ionic conductivity. The ASSBs based on the as‐prepared Ca-CeO2/LiTFSI/PEO composite electrolyte deliver high‐rate capability and high‐voltage stability.
Offering high energy density and high safety, all-solid-state lithium-sulfur batteries (ASSLSBs) have emerged as one of the most promising next-generation energy storage systems. However, there are a series of barriers to their practical applications, including insufficient sulfur utilization, low ionic conductivity and unstable interfaces. In the fourth study, we adopt acetamide to construct a deep eutectic system to suppress electrode passivation, and therefore address the issues of sulfur utilization, and improve the ionic conductivity of the solid polymer electrolytes. Furthermore, we establish a lithium bis(trifluoromethanesulfonyl)imide - lithium oxalyldifluoroborate (LiTFSI-LiDFOB) dual-salt system to facilitate the establishment of a stable and uniform passivation layer, a favorable interface on lithium anode, to prevent lithium dendrite formation and the polysulfide shuttling. Consequently, the as-prepared ASSLSBs deliver a high initial discharge specific capacity of 1012 mAh g-1 at 0.05 C and a stable capacity of 234.84 mAh g-1 after 1000 cycles at 0.1 C. This work suggests that the simultaneous adoption of the deep eutectic system and dual-salt electrolyte could accelerate the practical applications of ASSLSBs.
In summary, the high performance of the as-prepared silicon anodes demonstrates potential for addressing the challenges for next-generation anodes by designing self-healing polymers and aqueous hydrophilic polymers. Moreover, the success of the aqueous hydrophilic polymer in lithium-sulfur batteries suggests that such a binder system can be extended to other high-capacity energy storage materials that suffer from severe volume changes. As for the polymer electrolytes, the design of functional inorganic/polymeric composite electrolyte presents a promising strategy to resolve the stubborn barriers (i.e., insufficient contact at the interfaces and ionic conductivity) of ASSBs. Additionally, combining the merits of the deep eutectic system and the dual-salt system, long-term cycling stability and high capacity retention of ASSLSBs can be achieved. These polymeric binders and electrolytes can be further optimized to realize high performance for various energy storage systems.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Environment and ScScience, Environment, Engineering and TechnologyFull Tex
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)
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