213 research outputs found
Quantum Dots and Andreev Reflections in Graphene
No full textGraphene is an exceptionally thin semiconductor that consists of only one atomic layer of carbon atoms. The electrons in graphene live in a strictly two-dimensional (2D) world. In addition to this remarkable 2Dness, it is also peculiar that the behavior of the electrons in graphene is governed by the Dirac equation rather than the well known Schrödinger’s equation, leading to the discovery of several new physics phenomena. Such unusual properties of graphene have stirred up great excitements since it was first isolated in the lab about five years ago. In this thesis, we investigate the low temperature transport properties of the electrons and holes in several graphene based nano-devices. Overall, two topics are explored in this thesis. First we engineer an energy gap in graphene, which is naturally a zero-gap semiconductor, and further form quantum dot devices on the gapped graphene. The low temperature electronic transport properties of the confined electrons are then studied experimentally in such graphene dots. In a second project,we fabricated Josephson junction devices on graphene using a high critical field superconductor as leads. Here the goal is to research on the interactions between the electrons from graphene and the Cooper pairs from the superconductor in the quantum Hall regime.Kavli Institute of Nanoscience DelftApplied Science
Corrigendum to “Structural and optical characterization of high-quality ZnO thin films deposited by reactive RF magnetron sputtering” [Mater. Res. Bull. 48 (2013) 1093–1098]
No full textThe authors regret that in the above-mentioned paper, the author list "X.L. Zhanga, K.N. Huia,*, K.S. Huib,**, Jai Singha" is incorrect. This author list should read as follows: "Jai Singha, X.L. Zhanga, K.S. Huib,*, K.N. Huia,**". The authors regret that in the above-mentioned paper, the Acknowledgement "This work is supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology 2010-0023418). This project is also funded by the I2RF of City University of Hong Kong (project no. of 9666010)" is incorrect. This Acknowledgement should read as follows: "This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology 2010-0023418), the 2012 Post-Doc. Development Program of Pusan National University, and the I2RF of City University of Hong Kong (project no. of 9666010)." The authors would like to apologise for any inconvenience caused
Carbon nanotubes as a 1D template for the synthesis of air sensitive materials: about the confinement effect
No full textCobalt ferrite and cobalt iron nanowires with an average diameter of 50 nm and lengths up to several micrometers were synthesized inside multi-walled carbon nanotubes (MWNTs) under mild reaction conditions, i.e. 100 °C and atmospheric pressure, using an aqueous nitrate precursor salt filling the tubes. The concept of a confinement effect inside carbon nanotubes has been advanced to explain the formation of CoFe2O4 under such mild reaction conditions. The formation of caps near the tube tips at the beginning of the nitrate decomposition meant that each nanotube was considered as a closed nanoreactor, in which the reaction conditions could be very different to the macroscopic conditions outside the tube. The subsequent reduction of the CoFe2O4 allowed to obtain CoFe nanowires cast in the carbon nanotubes. These nanowires exhibit a high resistance towards oxidation, whereas bulk CoFe is known to undergo oxidation at room temperature and atmospheric pressure. This phenomenon was attributed to oxygen diffusion problems due to the confinement effect of the carbon nanotubes
Gravity field modeling on the basis of GRACE range-rate combinations: Current results and challenge
No full textGeoscience and Remote SensingCivil Engineering and Geoscience
Deformation behaviors at various temperatures and corresponding microscturcures of TiNiHf alloy
No full textThe deformation behaviors at various temperatures and corresponding microstructures of TiNiHf high temperature shape memory alloy had been studied. The tensile behavior of the TiNiHf alloy is characterized by continuous yielding and high work hardening in the temperature range from 293 K to 673 K. The critical stress for martensite variant reorientation is relatively high and a maximum elongation of about 30% is observed at about 510 K. No superelasticity is observed. The substructure of SIM and deformed SIM in the present alloy is (001) compound twin. Martensite variants are (011) type I twin related. Further increasing the déformation temperature and strain, the preferential oriented SIM gradually develop to martensite variants with variant-crack/variant-intersect morphologies
Modified hairpin lambda/2 resonator for high T-c SQUID
No full textIn order to understand the nature of the hairpin resonator suggested by Zhang et.al. [IEEE Trans. Appl. Supercond. (1996)], we have investigated a circuit with the similar structure. It is found that the tank circuits manifested the behaviour of lambda/2 resonator, instead of an LC one. The resonant frequency agrees with the prediction of theory for transmission line. We have found the data reported by Zhang et.al. are also consistent with the relation. This understanding enables us to design a lambda/2 resonator of the transmission line with a desired resonant frequency and a proper impedance to match the readout electronics easily.Physics, AppliedSCI(E)EI
A Maluku Sea intermediate western boundary current connecting Pacific Ocean circulation to the Indonesian Throughflow
No full text© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Yuan, D., Yin, X., Li, X., Corvianawatie, C., Wang, Z., Li, Y., Yang, Y., Hu, X., Wang, J., Tan, S., Surinati, D., Purwandana, A., Wardana, A., Ismail, M., Budiman, A., Bayhaqi, A., Avianto, P., Santoso, P., Kusmanto, E., Dirhamsyah, Arifin, Z., & Pratt, L. A Maluku Sea intermediate western boundary current connecting Pacific Ocean circulation to the Indonesian Throughflow. Nature Communications, 13(1), (2022): 2093, https://doi.org/10.1038/s41467-022-29617-6.The Indonesian Throughflow plays an important role in the global ocean circulation and climate. Existing studies of the Indonesian Throughflow have focused on the Makassar Strait and the exit straits, where the upper thermocline currents carry North Pacific waters to the Indian Ocean. Here we show, using mooring observations, that a previous unknown intermediate western boundary current (with the core at ~1000 m depth) exists in the Maluku Sea, which transports intermediate waters (primarily the Antarctic Intermediate Water) from the Pacific into the Seram-Banda Seas through the Lifamatola Passage above the bottom overflow. Our results suggest the importance of the western boundary current in global ocean intermediate circulation and overturn. We anticipate that our study is the beginning of more extensive investigations of the intermediate circulation of the Indo-Pacific ocean in global overturn, which shall improve our understanding of ocean heat and CO2 storages significantly.This study is supported by NSFC (D.Y., Z.W., Y.L., Y.Y., S.T., J.W., and X.L.: 41720104008; D.Y., J.W., Y.L., X.L., Y.Y., S.T., X.H., and X.Y.: 91858204), the National Key Research and Development Program of China (D.Y. and X.L.: 2020YFA0608800), CAS (D.Y., Z.W., J.W., and Y.L.: XDB42000000), projects. Affiliations 1 and 2 share the first position. D.Y. is supported by QMSNL (2018SDKJ0104-02), and Shandong Provincial (U1606402) and the “Kunpeng Outstanding Scholar Program” of the FIO/NMR of China, J.W. supported by NSFC (41776011), Z.W. by NSFC (41876025)
Founder's Day, circa 1980
No full textWritten on verso: (L-R) Dr. Louis Sullivan, Dr. X.L. Neal, Dr. Gloster Founder's Day Banquet - 1980.The Atlanta University Center Robert W. Woodruff Library acknowledges the generous support of the Council on Library and Information Resources (CLIR) in supporting the processing and digitization of a number of historic collections as part of the project: Our Story: Digitizing Publications and Photographs of the Historically Black Atlanta University Center Institutions.</em
Enhancing the internet of things with knowledge-driven software-defined networking technology : Future perspectives
No full textThe Internet of Things (IoT) connects smart devices to enable various intelligent services. The deployment of IoT encounters several challenges, such as difficulties in controlling and managing IoT applications and networks, problems in programming existing IoT devices, long service provisioning time, underused resources, as well as complexity, isolation and scalability, among others. One fundamental concern is that current IoT networks lack flexibility and intelligence. A network-wide flexible control and management are missing in IoT networks. In addition, huge numbers of devices and large amounts of data are involved in IoT, but none of them have been tuned for supporting network management and control. In this paper, we argue that Software-defined Networking (SDN) together with the data generated by IoT applications can enhance the control and management of IoT in terms of flexibility and intelligence. We present a review for the evolution of SDN and IoT and analyze the benefits and challenges brought by the integration of SDN and IoT with the help of IoT data. We discuss the perspectives of knowledge-driven SDN for IoT through a new IoT architecture and illustrate how to realize Industry IoT by using the architecture. We also highlight the challenges and future research works toward realizing IoT with the knowledge-driven SDN.Funding details: Academy of Finland, 318927, 326305, 325570, 3196669, 324576, 325774, 319670; Funding text 1: The research of Y.L. was partly done during her visit in Stockholm University. The research of X.S., P.H., X.L., S.T. and J.R. was partially funded by Academy of Finland, grant number 3196669, 319670, 324576, 325570, 326305, 318927 and 325774. The work of A.Y.D. was partially supported by the Do IoT Fieldlab and iSafe Project with funding from TU Delft Safety & Security Institute.</p
DEOS mass transport model (DMT-1) based on GRACE satellite data: Methodology and validation
No full textDEOSAerospace Engineerin
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