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115 results on '"Chen, Xumin"'

2. A Tabu-Based Multi-objective Particle Swarm Optimization for Irregular Flight Recovery Problem

Author

Zhou, Tianwei, Lai, Yichen, Huang, Xiaojie, Chen, Xumin, Zhong, Huifen, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Xu, Yuan, editor, Yan, Hongyang, editor, Teng, Huang, editor, Cai, Jun, editor, and Li, Jin, editor

Published
2023
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3. Comparative Analysis of Disney+ and Netflix in Post-covid19 Era

Author

Chen, Xumin, Liu, Xinxiang, Wang, Xuanji, Striełkowski, Wadim, Editor-in-Chief, Black, Jessica M., Series Editor, Butterfield, Stephen A., Series Editor, Chang, Chi-Cheng, Series Editor, Cheng, Jiuqing, Series Editor, Dumanig, Francisco Perlas, Series Editor, Al-Mabuk, Radhi, Series Editor, Scheper-Hughes, Nancy, Series Editor, Urban, Mathias, Series Editor, Webb, Stephen, Series Editor, Zhan, Zehui, editor, Chew, Fong Peng, editor, and Anthony, Marcus T., editor

Published
2023
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7. Target Control of Directed Networks based on Network Flow Problems

Author

Li, Guoqi, Chen, Xumin, Tang, Pei, Xiao, Gaoxi, Wen, Changyun, and Shi, Luping

Subjects
Computer Science - Systems and Control
Abstract

Target control of directed networks, which aims to control only a target subset instead of the entire set of nodes in large natural and technological networks, is an outstanding challenge faced in various real world applications. We address one fundamental issue regarding this challenge, i.e., for a given target subset, how to allocate a minimum number of control sources which provide input signals to the network nodes. This issue remains open in general networks with loops. We show that the issue is essentially a path cover problem and can be further converted into a maximum network flow problem. A method termed `Maximum Flow based Target Path-cover' (MFTP) with complexity $O(|V|^{1/2}|E|)$ in which $|V|$ and $|E|$ denote the number of network nodes and edges is proposed. It is also rigorously proven to provide the minimum number of control sources on arbitrary directed networks, whether loops exist or not. We anticipate that this work would serve wide applications in target control of real-life networks, as well as counter control of various complex systems which may contribute to enhancing system robustness and resilience.

Published
2018

16. Ultrathin BaTiO3 templates for multiferroic nanostructures

Author

Chen, Xumin, Yang, Seolun, Kim, Ji-Hyun, Kim, Hyung-Do, Kim, Jae-Sung, Rojas, Geoffrey, Skomski, Ralph, Lu, Haidong, Bhattacharya, Anand, Santos, Tiffany, Guisinger, Nathan, Bode, Matthias, Gruverman, Alexei, and Enders, Axel

Subjects
Condensed Matter - Materials Science
Abstract

Structural, electronic and dielectric properties of high-quality ultrathin BaTiO3 films are investigated. The films, which are grown by ozone-assisted molecular beam epitaxy on Nb-doped SrTiO3 (001) substrates and having thicknesses as thin 8 unit cells (3.2 nm), are unreconstructed and atomically smooth with large crystalline terraces. A strain-driven transition to 3D island formation is observed for films of of 13 unit cells thickness (5.2 nm). The high structural quality of the surfaces, together with the dielectric properties similar to bulk BaTiO3 and dominantly TiO2 surface termination, make these films suitable templates for the synthesis of high-quality metal-oxide multiferroic heterostructures for the fundamental study and exploitation of magneto-electric effects, such as a recently proposed interface effect in Fe/BaTiO3 heterostructures based on Fe-Ti interface bonds.

Published
2011
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17. Surface state engineering of molecule-molecule interactions

Author

Rojas, Geoffrey, Chen, Xumin, Kunkel, Donna, Nitz, Justin, Xiao, Jie, Dowben, Peter A., Simpson, Scott, Zurek, Eva, and Enders, Axel

Subjects
Condensed Matter - Materials Science
Abstract

Engineering the electronic structure of organics through interface manipulation, particularly the interface dipole and the barriers to charge carrier injection, is of essential importance to improved organic devices. This requires the meticulous fabrication of desired organic structures by precisely controlling the interactions between molecules. The well-known principles of organic coordination chemistry cannot be applied without proper consideration of extra molecular hybridization, charge transer and dipole formation at the interfaces. Here we identify the interplay between energy level alignment, charge transfer, surface dipole and charge pillow effect and show how these effects collectively determine the net force between adsorbed porphyrin 2H-TPP on Cu(111). We show that the forces between supported porphyrins can be altered by controlling the amount of charge transferred across the interface accurately through the relative alignment of molecular electronic levels with respect to the Shockley surface state of the metal substrate, and hence govern the self-assembly of the molecules.

Published
2011
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18. A Flexible Electret Membrane with Persistent Electrostatic Effect and Resistance to Harsh Environment for Energy Harvesting

Author

Xiao Huiming, Chen Gangjin, Chen Xumin, and Chen Zhi

Subjects
Medicine, Science
Abstract

Abstract A novel flexible electret membrane, exhibiting persistent electrostatic effect, distinctive temperature stability and outstanding capability of resistance to harsh environment and fatigue, is demonstrated by experiment. Its excellent electret performance is correlated to the synergy of three factors, which are space charge injection, dipole orientation and interfacial polarization according to the analysis of charge storage mechanism. This electret membrane is provided with sandwich configuration PTFE/THV/PTFE, prepared by hot pressing method and thermal charging technology. After wiped its surface with alcohol, its surface potential declines to zero from −550 V, then recovers rapidly to −310 V and finally maintains constant for 800 hours, which shows that its electret performance distinctly precedes traditional electret material such as single PTFE, FEP electret membrane. The measurement of thermal stimulating potentials displays that its surface potential reaches maximum about 5 times initial value at 125 °C. A micro-vibration energy harvester is assembled with this membrane. Its maximum output power reaches 4.66 μW at tapping frequency 5 Hz and keeps stable during over 2000 tapping tests within 100 days, which indicates the long-life service and resistance to harsh environment and fatigue of this electret membrane.

Published
2017
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23. Effect of sex on the association between arterial partial pressure of oxygen and in-hospital mortality in ICU patients with cardiogenic shock: a retrospective cohort study

Author

Zhao, Ning, primary, Pan, Zelin, additional, Yang, Qilin, additional, Chen, Juanmei, additional, Ruan, Dongxue, additional, Huang, Meiqi, additional, Lu, Peilin, additional, Chen, Xumin, additional, Huang, Xinqiao, additional, Lin, Xiaozhen, additional, and Mo, Pei, additional

Published
2022
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25. Group-based social diffusion in recommendation

Author

Chen, Xumin, primary, Xie, Ruobing, additional, Qiu, Zhijie, additional, Cui, Peng, additional, Zhang, Ziwei, additional, Liu, Shukai, additional, Yang, Shiqiang, additional, Zhang, Bo, additional, and Lin, Leyu, additional

Published
2022
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35. A Laser Decontamination Technology for Radioactive Contaminated Metals

Author

Cao Junjie, Chen Xumin, Wang Shuai, Zhang Yongling, and Zhao Wan

Subjects
Laser ablation, Materials science, Waste management, law, Human decontamination, Contamination, Laser, law.invention
Abstract

A large number of radioactive contaminated metals will be produced during the operation and decommissioning of nuclear facilities. Laser ablation is a clean and efficient surface decontamination method for radioactive metals. This study presents experiments to select laser decontamination parameters including laser power, laser pulse width, laser scanning speed and laser focal shift, as well as the construction of a laser decontamination prototype based on a fiber laser system of high power density, which can automatically ablate the radioactive deposit layer, oxide layer and shallow surface layer of metals to get an excellent decontamination result. Depending on this equipment, some engineering application tests were conducted in a nuclear power factory to verify the technology research result and equipment. Decontamination results which evaluate by decontamination factor show that the laser decontamination technology has a good result on the decontamination of radioactive surface contaminated metals.

Published
2020

38. A Flexible Electret Membrane with Persistent Electrostatic Effect and Resistance to Harsh Environment for Energy Harvesting

Author

Chen Zhi, Chen Gangjin, Xiao Huiming, and Chen Xumin

Subjects
Multidisciplinary, Materials science, Science, Interfacial polarization, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Hot pressing, 01 natural sciences, Space charge, Article, 0104 chemical sciences, Dipole, Membrane, Thermal, Medicine, Electret, Composite material, 0210 nano-technology, Energy harvesting
Abstract

A novel flexible electret membrane, exhibiting persistent electrostatic effect, distinctive temperature stability and outstanding capability of resistance to harsh environment and fatigue, is demonstrated by experiment. Its excellent electret performance is correlated to the synergy of three factors, which are space charge injection, dipole orientation and interfacial polarization according to the analysis of charge storage mechanism. This electret membrane is provided with sandwich configuration PTFE/THV/PTFE, prepared by hot pressing method and thermal charging technology. After wiped its surface with alcohol, its surface potential declines to zero from −550 V, then recovers rapidly to −310 V and finally maintains constant for 800 hours, which shows that its electret performance distinctly precedes traditional electret material such as single PTFE, FEP electret membrane. The measurement of thermal stimulating potentials displays that its surface potential reaches maximum about 5 times initial value at 125 °C. A micro-vibration energy harvester is assembled with this membrane. Its maximum output power reaches 4.66 μW at tapping frequency 5 Hz and keeps stable during over 2000 tapping tests within 100 days, which indicates the long-life service and resistance to harsh environment and fatigue of this electret membrane.

Published
2017

39. Author Correction: A Flexible Electret Membrane with Persistent Electrostatic Effect and Resistance to Harsh Environment for Energy Harvesting

Author

Chen Gangjin, Chen Zhi, Chen Xumin, and Xiao Huiming

Subjects
Multidisciplinary, Materials science, lcsh:R, lcsh:Medicine, Nanotechnology, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Membrane, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, lcsh:Q, Electret, lcsh:Science, Author Correction, 0210 nano-technology, Energy harvesting
Abstract

A novel flexible electret membrane, exhibiting persistent electrostatic effect, distinctive temperature stability and outstanding capability of resistance to harsh environment and fatigue, is demonstrated by experiment. Its excellent electret performance is correlated to the synergy of three factors, which are space charge injection, dipole orientation and interfacial polarization according to the analysis of charge storage mechanism. This electret membrane is provided with sandwich configuration PTFE/THV/PTFE, prepared by hot pressing method and thermal charging technology. After wiped its surface with alcohol, its surface potential declines to zero from -550 V, then recovers rapidly to -310 V and finally maintains constant for 800 hours, which shows that its electret performance distinctly precedes traditional electret material such as single PTFE, FEP electret membrane. The measurement of thermal stimulating potentials displays that its surface potential reaches maximum about 5 times initial value at 125 °C. A micro-vibration energy harvester is assembled with this membrane. Its maximum output power reaches 4.66 μW at tapping frequency 5 Hz and keeps stable during over 2000 tapping tests within 100 days, which indicates the long-life service and resistance to harsh environment and fatigue of this electret membrane.

Published
2018

44. Reduction of Intrinsic Electron Emittance from Photocathodes Using Ordered Crystalline Surfaces

Author

Department of Energy (US), National Science Foundation (US), Ministerio de Economía y Competitividad (España), Karkare, Siddharth, Feng, Jun, Chen, Xumin, Wan, Weishi, Palomares, F. Javier, Chiang, T. C., Padmore, Howard A., Department of Energy (US), National Science Foundation (US), Ministerio de Economía y Competitividad (España), Karkare, Siddharth, Feng, Jun, Chen, Xumin, Wan, Weishi, Palomares, F. Javier, Chiang, T. C., and Padmore, Howard A.

Abstract

The generation of intense electron beams with low emittance is key to both the production of coherent x rays from free electron lasers, and electron pulses with large transverse coherence length used in ultrafast electron diffraction. These beams are generated today by photoemission from disordered polycrystalline surfaces. We show that the use of single crystal surfaces with appropriate electronic structures allows us to effectively utilize the physics of photoemission to generate highly directed electron emission, thus reducing the emittance of the electron beam being generated.

Published
2017

47. Spin polarization asymmetry at the surface of chromia

Author

Cao, Shi, primary, Zhang, Xin, additional, Wu, Ning, additional, N’Diaye, A T, additional, Chen, G, additional, Schmid, A K, additional, Chen, Xumin, additional, Echtenkamp, W, additional, Enders, A, additional, Binek, Ch, additional, and Dowben, P A, additional

Published
2014
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48. Ultrathin oxide films as templates for magnetic nanostructures

Author

Chen, Xumin and Chen, Xumin

Abstract

The study of ultrathin oxide film as templates for magnetic nanostructures is presented. The ultrathin oxide thin films are investigated for the surface morphology, electronic properties, surface terminations, and ferroelectric properties by the combination of various local and non-local surface science techniques. Ultrathin oxide films, only a few unit cells in thickness, have significant advantages over bulk oxides, such as atomically defined, unreconstructed and stoichiometric surfaces. The high structural quality makes them suitable templates for the fabrication of metal-oxide heterostructures with unprecedented interface quality. This is expected to enable the studies of fundamental interactions between the oxide and metallic adsorbates, such as the theoretically predicted magnetoelectric coupling based on interfacial Fe-Ti bonds. Two kinds of oxide films, BaTiO3 and Cr2O3, are discussed. Scanning tunneling microscopy is utilized to investigate their structure and electronic properties. Firstly, studies of magnetism of Fe nanoclusters deposited on BaTiO3 by X-ray absorption and photoelectron spectroscopy demonstrate that the oxidization of Fe is largely suppressed by the molecular beam epitaxy growth at low temperature so that even isolated Fe atoms on the BaTiO 3 have significant magnetic moments. As a second example, the growth and characterization of ultrathin chromia film are discussed. The thin chromia films exhibit highly ordered and atomically smooth surfaces. The electronic structure is locally explored with scanning tunneling spectroscopy, to resolve surface termination and polarization. The presented studies on the ultrathin oxide films are expected to advance the fundamental understanding of interface effects in multiferroics and may help improving magneto-electric effects. In a third example, the formation of magnetic Co nanoclusters on boron nitride nanotemplates is analyzed. The analytic models and Monte-Carlo simulations for the analysis of the c

Published
2013

49. Magnetic phases of cobalt atomic clusters on tungsten

Author

Lukashev, Pavel V., Kim, Ji-Hyun, Yang, Seolum, Kim, Jae-Sung, Chen, Xumin, Rojas, Geoffrey, Honolka, Jan, Skomski, Ralph, Enders, Axel, Sabirianov, Renat F., Lukashev, Pavel V., Kim, Ji-Hyun, Yang, Seolum, Kim, Jae-Sung, Chen, Xumin, Rojas, Geoffrey, Honolka, Jan, Skomski, Ralph, Enders, Axel, and Sabirianov, Renat F.

Abstract

First-principle calculations are employed to show that the magnetic structure of small atomic clusters of Co, formed on a crystalline W(110) surface and containing 3–12 atoms, strongly deviates from the usual stable ferromagnetism of Co in other systems. The clusters are ferri-, ferro- or non-magnetic, depending on cluster size and geometry. We determine the atomic Co moments and their relative alignment, and show that antiferromagnetic spin alignment in the Co clusters is caused by hybridization with the tungsten substrate and band filling. This is in contrast with the typical strong ferromagnetism of bulk Co alloys, and ferromagnetic coupling in Fe/W(110) clusters.

Published
2013

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