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232 results on '"Zeng, Zhixin"'

3. Privacy-Preserving Electricity Theft Detection based on Blockchain

Author

Zhao, Zhiqiang, Liu, Yining, Zeng, Zhixin, Chen, Zhixiong, and Zhou, Huiyu

Subjects
Computer Science - Cryptography and Security
Abstract

In most electricity theft detection schemes, consumers' power consumption data is directly input into the detection center. Although it is valid in detecting the theft of consumers, the privacy of all consumers is at risk unless the detection center is assumed to be trusted. In fact, it is impractical. Moreover, existing schemes may result in some security problems, such as the collusion attack due to the presence of a trusted third party, and malicious data tampering caused by the system operator (SO) being attacked. Aiming at the problems above, we propose a blockchain-based privacy-preserving electricity theft detection scheme without a third party. Specifically, the proposed scheme uses an improved functional encryption scheme to enable electricity theft detection and load monitoring while preserving consumers' privacy; distributed storage of consumers' data with blockchain to resolve security problems such as data tampering, etc. Meanwhile, we build a long short-term memory network (LSTM) model to perform higher accuracy for electricity theft detection. The proposed scheme is evaluated in a real environment, and the results show that it is more accurate in electricity theft detection within acceptable communication and computational overhead. Our system analysis demonstrates that the proposed scheme can resist various security attacks and preserve consumers' privacy., Comment: 13 pages

Published
2023
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4. Evaluating the Perceived Safety of Urban City via Maximum Entropy Deep Inverse Reinforcement Learning

Author

Wang, Yaxuan, Zeng, Zhixin, and Zhao, Qijun

Subjects
Computer Science - Machine Learning, Computer Science - Artificial Intelligence
Abstract

Inspired by expert evaluation policy for urban perception, we proposed a novel inverse reinforcement learning (IRL) based framework for predicting urban safety and recovering the corresponding reward function. We also presented a scalable state representation method to model the prediction problem as a Markov decision process (MDP) and use reinforcement learning (RL) to solve the problem. Additionally, we built a dataset called SmallCity based on the crowdsourcing method to conduct the research. As far as we know, this is the first time the IRL approach has been introduced to the urban safety perception and planning field to help experts quantitatively analyze perceptual features. Our results showed that IRL has promising prospects in this field. We will later open-source the crowdsourcing data collection site and the model proposed in this paper., Comment: ACML2022 Camera-ready Version

Published
2022

5. In situ micropillar compression of an anisotropic metal-organic framework single crystal

Author

Zeng, Zhixin, Xiao, Yuan, Wheeler, Jeffrey M., and Tan, Jin-Chong

Subjects
Condensed Matter - Materials Science, Condensed Matter - Soft Condensed Matter
Abstract

Understanding of the complex mechanical behavior of metal-organic frameworks (MOF) beyond their elastic limit will allow the design of real-world applications in chemical engineering, optoelectronics, energy conversion apparatus, and sensing devices. Through in situ compression of micropillars, the uniaxial stress-strain curves of a copper paddlewheel MOF (HKUST-1) were determined along two unique crystallographic directions, namely the (100) and (111) facets. We show strongly anisotropic elastic response where the ratio of the Young's moduli are E(111) ~ 3.6 x E(100), followed by extensive plastic flows. Likewise, the yield strengths are considerably different, in which Y(111) ~ 2 x Y(100) because of the underlying framework anisotropy. We measure the fracture toughness using micropillar splitting. While in situ tests revealed differential cracking behavior, the resultant toughness values of the two facets are comparable, yielding Kc ~ 0.5 MPa m^1/2. This work provides new insights of porous framework ductility at the micron scale and failure by bonds breakage., Comment: 20 pages, 4 figures, Supplementary Information

Published
2022

13. Impact of pressure and temperature on the broadband dielectric response of the HKUST-1 metal-organic framework

Author

Babal, Arun S., Donà, Lorenzo, Ryder, Matthew R., Titov, Kirill, Chaudhari, Abhijeet K., Zeng, Zhixin, Kelley, Chris S., Frogley, Mark D., Cinque, Gianfelice, Civalleri, Bartolomeo, and Tan, Jin-Chong

Subjects
Condensed Matter - Materials Science, Condensed Matter - Soft Condensed Matter
Abstract

Herein we employed high-resolution spectroscopic techniques in combination with periodic ab initio density functional theory (DFT) calculations to establish the different polarization processes for a porous copper-based MOF, termed HKUST-1. We used alternating current measurements to determine its dielectric response between 4 Hz and 1.5 MHz where orientational polarization is predominant, while synchrotron infrared (IR) reflectance was used to probe the far-IR, mid-IR, and near-IR dielectric response across the 1.2 THz to 150 THz range (ca. 40 - 5000 cm^-1) where vibrational and optical polarizations are principal contributors to its dielectric permittivity. We demonstrate the role of pressure on the evolution of broadband dielectric response, where THz vibrations reveal distinct blue and red shifts of phonon modes from structural deformation of the copper paddle-wheel and the organic linker, respectively. We also investigated the effect of temperature on dielectric constants in the MHz region pertinent to microelectronics, to study temperature-dependent dielectric losses via dissipation in an alternating electric field. The DFT calculations offer insights into the physical mechanisms responsible for dielectric transitions observed in the experiments and enable us to explain the frequency shifts phenomenon detected under pressure. Together, the experiments and theory have enabled us to glimpse into the complex dielectric response and mechanisms underpinning a prototypical MOF subject to pressure, temperature, and vast frequencies., Comment: 20 pages, 6 figures, plus Supporting Information

Published
2019

15. Effect of sintering temperatures on the magnetoelectric properties of Bi0.78La0.08Sm0.14Fe0.85Ti0.15O3 ceramics

Author

Ao Hong, Wu Heng, Li Wenchuan, Lan Mengshuang, Zeng Zhixin, Zhang Qin, Gao Rongli, Deng Xiaoling, Chen Gang, Fu Chunlin, Wang Zhenhua, Lei Xiang, and Cai Wei

Subjects
multiferroics, doped bifeo3, ferroelectric, magnetic and dielectric properties, Clay industries. Ceramics. Glass, TP785-869
Abstract

Multiferroic materials attracted much attention because of magnetoelectric (ME) coupling effect. Herein, a typical single-phase multiferroic BiFeO3 (BFO) was co-doped at A and B sites by solid-state method, and Bi0.78La0.08Sm0.14Fe0.85Ti0.15O3 (BLSFTO) ceramics were prepared at different sintering temperatures (940, 960, 980 and, 1000°C). The effects of sintering temperature on the microstructure, morphology, dielectric, ferroelectric and magnetic properties were systematically studied. The remanent polarization (Pr) and coercive field (Ec) of the BLSFTO ceramics show a non-linear change with sintering temperature. The remanent polarization reaches maximum (0.0560 μC/cm2) in the sample sintered at 1000°C, whereas the maximum Ec of 1.32 kV/cm was obtained in the specimen sintered at 940°C. The remanent magnetization (Mr) increases with the increase of sintering temperature, while change of the saturation magnetization with sintering temperature is negligible. When BLSFTO specimen is sintered at 1000°C, Mr reaches the maximal value of 0.1344 emu/g.

Published
2022
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16. Influence of calcination temperature on structure and multiferroic properties of barium ferrite ceramics

Author

Zeng Zhixin, Zhang Qin, Wu Heng, Lan Mengshuang, Ao Hong, Li Wenchuan, Zhou Chuang, He Jizhuang, Xing Shulin, Deng Xiaoling, and Gao Rongli

Subjects
barium ferrite, sol-gel method, calcination temperature, multiferroic properties, Clay industries. Ceramics. Glass, TP785-869
Abstract

In this paper, barium ferrite powders were synthesized by sol-gel method, calcined at different temperatures, and on this basis the corresponding ceramics were prepared. The effects of calcination temperature on the structure, magnetic, dielectric and multiferroic properties of BaFe12O19 ceramics were studied. XRD results confirmed similarity between powders and ceramics, where dominant phase is BaFe12O19 and a small amount of an apparent BaFe2O4 impurity phase was formed at lower calcination temperature. The impurity BaFe2O4 phase is the main reason for decreasing powder magnetization. The maximum dielectric constant of 100 (at 10 kHz) and maximum remanent polarization, remanent magnetization and saturation magnetization of 0.46 μC/cm2, 47.37 emu/g and 79.96 emu/g, respectively, were obtained in the barium ferrite ceramics prepared from the powder calcined at 1100°C. This research could be the basis for the study of single-phase multiferroic materials and the development of multi-order electronic devices.

Published
2022
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18. Dielectric Properties of Metal-Organic Frameworks Probed via Synchrotron Infrared Reflectivity

Author

Ryder, Matthew R., Zeng, Zhixin, Sun, Yueting, Flyagina, Irina, Titov, Kirill, Mahdi, E. M., Bennett, Thomas D., Civalleri, Bartolomeo, Kelley, Chris S., Frogley, Mark D., Cinque, Gianfelice, and Tan, Jin-Chong

Subjects
Condensed Matter - Materials Science
Abstract

We present the frequency-dependant (dynamic) dielectric response of a group of topical polycrystalline zeolitic imidazolate-based metal-organic framework (MOF) materials in the extended infrared spectral region. Using synchrotron-based FTIR spectroscopy in specular reflectance, in conjunction with density functional theory (DFT) calculations, we have revealed detailed structure-property trends linking the THz region dielectric response to framework porosity and structural density. The work demonstrates that MOFs are promising candidate materials not only for low-\k{appa} electronics applications but could also be pioneering for terahertz (THz) applications, such as next-generation broadband communications technologies., Comment: 6 pages, 5 figures

Published
2018

22. Blockchain-Based Decentralized Privacy-Preserving Data Aggregation (BDPDA) : Scheme for SmartGrid

Author

Fan, Hongbin, Liu, Yining, Zeng, Zhixin, Akan, Ozgur, Editorial Board Member, Bellavista, Paolo, Editorial Board Member, Cao, Jiannong, Editorial Board Member, Coulson, Geoffrey, Editorial Board Member, Dressler, Falko, Editorial Board Member, Ferrari, Domenico, Editorial Board Member, Gerla, Mario, Editorial Board Member, Kobayashi, Hisashi, Editorial Board Member, Palazzo, Sergio, Editorial Board Member, Sahni, Sartaj, Editorial Board Member, Shen, Xuemin (Sherman), Editorial Board Member, Stan, Mircea, Editorial Board Member, Jia, Xiaohua, Editorial Board Member, Zomaya, Albert Y., Editorial Board Member, Wang, Ding, editor, Meng, Weizhi, editor, and Han, Jinguang, editor

Published
2021
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23. Quantitative studies of the nanoscale mechanical properties of metal organic framework materials

Author

Zeng, Zhixin and Tan, Jin-Chong

Subjects
620.1, Quantitative Study, Engineering Science, Metal-Organic Framework (MOF), Mechanical Property Characterisation, Nanomaterial
Abstract

The nanoscale mechanical properties of metal-organic framework (MOF) materials including the elasticity (Young's modulus), plasticity (hardness, yield stress, ultimate strength, and work hardening coefficient), adhesion property (adhesive force and energy), and failure mechanisms (failure modes, corresponding threshold forces and failure strengths) have been studied in the range of sub-nm to ~100s nm in depth. MOF materials are a topical class of porous crystalline solids that are constructed from the self-assembly of metal clusters and organic linkers, to yield tuneable framework structures with a vast range of physical and chemical properties. Herein, three model MOF systems are of particular interest: the nanocrystals and micron-sized crystals of ZIF-8, two-dimensional nanosheets of CuBDC, and submillimetre-sized crystals of HKUST-1. The three MOF materials were prudently selected because they represent three distinctive structures in terms of the response to stress. In this work, depth-sensing nanoindentation techniques, particularly the 'conventional' instrumented indentation technique (force sensitivity ~ 50 nN) and the atomic force microscopy (AFM)-based nanoindentation (force sensitivity < 0.05 nN), have been intensively employed and adapted to enable the accurate characterisation of the fine-scale mechanical behaviour of MOF materials. By leveraging the force and displacement sensitivities of the AFM instrument, the AFM-based nanoindentation method has been rationally established and improved by extending its application to study MOF mechanics at the nanoscale. This is a challenging field that has not yet been rigorously addressed by means of detailed experiments. Amongst the depth-sensing techniques, the AFM-based nanoindentation measurements are usually criticised for their instability and low reproducibility. Herein, the major factors that could interfere with the measurement precision have been systematically investigated. The research has led to the development of comprehensive approaches for AFM instrumental controls to achieve reliable force-displacement data and improved contact models for nanoindentation data analysis. Quantification of the nanoscale mechanical properties sheds light on the complicated deformation behaviour of the porous MOF structures. AFM nanoindentation data obtained at the nanometre length scale reveal new structure-property information about the surface energy, incipient plasticity, and fracture mechanisms underpinning the inorganic-organic building blocks of MOF systems. Accurate materials data about mechanical performance and durability will be fundamental towards the development of functional devices and practical applications.

Published
2018

28. Performance Simulation Study of Vehicle Engine Cooling System

Author

Li, Xin, Zhu, Liang, Zhu, Yongcheng, Zeng, Zhixin, Liu, Jujiang, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Liang, Qilian, Series Editor, Martin, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zhang, Junjie James, Series Editor, and (China SAE), China Society of Automotive Engineers, editor

Published
2020
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40. An efficient solid shell material point method for large deformation of thin structures.

Author

Li, Jiasheng, Ni, Ruichen, Zeng, Zhixin, and Zhang, Xiong

Subjects
MATERIAL point method, FLUID-structure interaction, DEFORMATIONS (Mechanics), TIMOSHENKO beam theory
Abstract

The standard material point method (MPM) encounters severe numerical difficulties in simulating shell structures. In order to overcome the shortcomings of locking effects, the discretization size of background grid should be small enough, usually smaller than 1/5 of the shell thickness, which however will lead to prohibitive computational cost. A novel solid shell material point method (SSMPM) is proposed to efficiently model the large deformation of thin structures. The SSMPM describes the material domain of shell structures by shell particles with hexahedral particle domains. The locking treatments of solid shell element are then introduced in SSMPM, which results in the correction of strain field throughout the shell thickness. Namely, the assumed natural strain (ANS) method is adopted to eliminate the shear locking and trapezoidal locking, while the enhanced assumed strain (EAS) method is employed to eliminate the thickness locking. With the precise description of bending modes, a single layer of particles and a coarse background grid could be used in shell structure simulations with the SSMPM, which dramatically increases the computational efficiency. A local multi‐mesh contact method is presented to naturally couple SSMPM and MPM for the contact situations of shells with other objects. Several numerical examples, including beam vibration, pinched cylinder with free edges and full hemispherical shell, are performed to verify and validate the SSMPM, which shows that the SSMPM considerably outperforms the standard MPM in these situations. A fluid–structure interaction problem and the penetration of a thin plate are investigated based on the contact method and the results are in good agreement with those in the literature. [ABSTRACT FROM AUTHOR]

Published
2024
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41. Improved photomagnetoelectric properties of BiFeO3/CoFe2O4 films by using the size effect.

Author

Ding, Yiwen, Ren, KeJu, Zeng, Zhixin, Meng, Gang, Gao, Rongli, Deng, Xiaoling, Chen, Gang, Cai, Wei, Fu, Chunlin, Wang, Zhenhua, and Lei, Xiang

Subjects
PHOTOELECTRICITY, PHOTOVOLTAIC effect, ENERGY harvesting, REMANENCE, DIELECTRIC films, STRAY currents
Abstract

The potential applications of magnetoelectric composites in capacitors, sensors, memory electronic devices, and energy harvesting devices have aroused great interest due to their mutual coupling between ferroelectric and ferromagnetic phases. In this paper, BFO/CFO composite films were prepared by the sol–gel method, and the regulation of magneto-photoelectric and coupling properties of BFO/CFO films with different compositions was studied. The results show that with the increase of BFO composition, the interface between BFO layer and BFO layer also appears, the dielectric constant of the film decreases with increasing the content of BFO, and the photoelectric conversion efficiency of the film increases at first and then decreases with the increase of BFO content. When the composition is 4BFO/6CFO, the photoelectric conversion efficiency of the composite film is the highest, which is 2.02 × 10−3%. With the increase of CFO content, the remanent magnetization and saturation magnetization of the film increase gradually. However, when the compositions are 4BFO/6CFO and 3BFO/7CFO, their leakage current is high, resulting in the degradation of ferroelectric properties. The composition 5BFO/5CFO has the highest magnetodielectric and photo induced magnetodielectric response, the corresponding values are 2.21% and 3.88%, respectively. The magnetoelectric coupling coefficient of the film is greatly increased under the action of light, reaching 115%, which could plausibly relate to the photovoltaic effect and the photostriction effects of the film. These results may provide good guidance on designing new photoelectromagnetic detector. [ABSTRACT FROM AUTHOR]

Published
2024
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42. Quantum tunneling rotor as a sensitive atomistic probe of guests in a metal-organic framework

Author

Titov, Kirill, primary, Ryder, Matthew R., additional, Lamaire, Aran, additional, Zeng, Zhixin, additional, Chaudhari, Abhijeet K., additional, Taylor, James, additional, Mahdi, E. M., additional, Rogge, Sven M. J., additional, Mukhopadhyay, Sanghamitra, additional, Rudić, Svemir, additional, Van Speybroeck, Veronique, additional, Fernandez-Alonso, Felix, additional, and Tan, Jin-Chong, additional

Published
2023
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49. Effect of composition on magnetic and photoelectric properties of BiFeO3/CoFe2O4 thin films.

Author

Sun, Guiyun, Li, Huan, Zhong, Siqi, Chen, Chen, Ren, Keju, Zeng, Zhixin, Deng, Xiaoling, Gao, Rongli, Cai, Wei, Fu, Chunlin, Chen, Gang, Wang, Zhenhua, and Lei, Xiang

Abstract

Multiferroic materials have recently as a new useful material because they can exhibit a potent magnetoelectric interaction between the ferroelectric and ferromagnetic orders above ambient temperature. In this paper, BiFeO3/CoFe2O4(BFO/CFO) thin films were prepared by the spin-coating method, and the effects of composition on the crystal structure, surface morphology, electrical properties, magnetic properties, photovoltaic properties as well as magnetic and photoelectric coupling properties of the composite films were systematically investigated. The results show that the main crystal phases of the composite films are BFO and CFO, and there are no other heterozygous phases that can be observed. The AFM results show that the roughness of thin films ranges from 8 to 10 nm, and it increases with the increase of CFO composition on the whole. SEM results confirm that there is a clear interface between different phases of different constituent films, and no obvious diffusion phenomenon occurs. The saturation and residual magnetization values increase gradually with the increase of CFO content, and the magnetic properties are stronger. With the increase of BFO composition, the dielectric constant of the composite film gradually decreases. The photoelectric conversion efficiency of the composite film decreases with the increase of BFO content, and the maximum photoelectric conversion efficiency is 5.63 × 10−5% when the composition is 3BFO/7CFO. The maximum photomagnetic dielectric response is found when the composition of the film is 5BFO/5CFO. [ABSTRACT FROM AUTHOR]

Published
2023
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