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Mechanical property of artificial methane hydrate under triaxial compression

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Journal of Natural Gas Chemistry 2010年第3期19卷 246-250页

作者： Yongchen Song Feng Yu yanghui Li Weiguo liu Jiafei Zhao Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian 116024 Liaoning China

Methane production from hydrate reservoir may induce seabed slide and deformation of the hydrate-bearing *** research on mechanical properties of methane hydrate is considered to be important for developing an efficient methane exploitation *** this paper,a triaxial test system containing a pressure crystal device was developed with the conditions to stabilize the hydrate.A series of triaxial shear tests were carried out on artificial methane hydrate *** addition,mechanical characteristics of methane hydrate were studied with the strain rates of 0.1 and 1.0 mm/min,respectively,under the conditions of different temperatures（T =-5,-10,and-20 ℃） and confining pressures（P = 0,5,10,15,and 20 MPa）.The preliminary results show that when the confining pressure was less than 10 MPa,the increase of confining pressure leaded to the enhancement of shear ***,the decreasing temperature and the increasing strain rate both caused the increase in shear strength.

关键词： triaxial mechanical properties confining pressure temperature strain rate

Surface Passivation Performance of Atomic-Layer-Deposited Al_2O_3 on p-type Silicon Substrates

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Journal of Materials Science & Technology 2014年第8期30卷 835-838页

作者： yanghui liu Liqiang Zhu Liqiang Guo Hongliang Zhang Hui Xiao Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences

Surface passivation performances of Al2O3 layers deposited on p-type Czochralski Si wafers by atomic layer deposition（ALD） were investigated as a function of post-deposition annealing *** maximal minority carrier lifetime of 4.7 ms was obtained for AI2O3 passivated p-type *** passivation mechanisms of Al2O3 layers were investigated in terms of interfacial state density（Dit） and negative fixed charge densities（Qfix） through capacitance—voltage（C— V） *** density of Qfix and low density of Dit were needed for high passivation performances,while high density of Dit and low density of Qfixdegraded the passivation performances.A low Dit was a prerequisite to benefit from the strong field effect passivation induced by high density of negative fixed charges in the Al2O3 layer.

关键词： Atomic layer deposition Al2O3 Passivation Films

n-type Polycrystalhne Si Thick Films Deposited on SiN_x-coated Metallurgical Grade Si Substrates

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Journal of Materials Science & Technology 2015年第1期31卷 65-69页

作者： Hongliang Zhang Liqiang Zhu Liqiang Guo yanghui liu Qing Wan Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences

For photovoltaic applications,low-cost SiNx-coated metallurgical grade silicon（MG-Si） wafers were used as substrates for polycrystalline silicon（poly-Si） thick films deposition at temperatures ranging from 640 to880 ℃ by thermal chemical vapor deposition.X-ray diffraction and Raman results indicated that high-quality poly-Si thick films were deposited at 880 ℃.To obtain n-type poly-Si,the as-deposited poly-Si films were annealed at 880 ℃ capped with a phosphosilicate *** properties of the n-type poly-Si thick films were investigated by four-probe and Hall *** carrier concentration and electron mobility of the n-type poly-Si film was estimated to be 1.7 x 1019cm-3and 68.1 cm2V-1s-1,*** poly-Si thick films deposited on MG-Si wafers are very promising for photovoltaic applications.

关键词： Thermal chemical vapor deposition Metallurgical gr

Flexible Oxide-Based Thin-Film Transistors on Plastic Substrates for Logic Applications

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Journal of Materials Science & Technology 2015年第2期31卷 171-174页

作者： Jin Zhang yanghui liu Liqiang Guo Ning liu Hui Xiao Changqing Chen Guodong Wu Wuhan National Laboratory for Optoelectronics College of Optoelectronic Science and EngineeringHuazhong University of Science and Technology Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences

Phosphorus doped（P-doped） nanogranular SiO2 films have been deposited by plasma-enhanced chemical vapor deposition. A high proton conductivity of;.2x10-4S/cm and a large electric double layer（EDL） capacitance of;.2μF/cm2 have been obtained. Flexible coplanar-gate EDL thin film transistors（TFTs） gated by P-doped nanogranular SiO2 films are self-assembled on plastic substrates at room temperature. Due to the big EDL capacitance,such TFTs show ultra-low voltage operation of 1 V,a large field-effect mobility of 18.9 cm2/Vs,a small subthreshold swing of 85 m V/decade and a high current on/off ratio of 107. Furthermore,the EDL TFT could work in dual coplanar gate mode. AND logic operation is realized. Our results demonstrate that such TFTs gated by P-doped nanogranular SiO2 films have potential applications in low-power flexible electronics.

关键词： Flexible devices P-doped nanogranular SiO2 Electri

A multi-terminal ion-controlled transistor with multifunctionality and wide temporal dynamics for reservoir computing

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Nano Research 2024年第5期17卷 4444-4453页

作者： Kekang liu Jie Li Fangzhou Li Yiyuan Lin Hongrui liu Linzi Liang Zhiyuan Luo Wei liu Mengye Wang Feichi Zhou yanghui liu School of Materials Sun Yat-Sen UniversityShenzhen 518107China School of Microelectronics Southern University of Science and TechnologyShenzhen 518055China School of Software East China Jiaotong UniversityNanchang 330013China

Reservoir computing(RC)is an energy-efficient computational framework with low training cost and high efficiency in processing spatiotemporal *** state-of-the-art fully memristor-based hardware RC system suffers from bottlenecks in the computation efficiencies and accuracy due to the limited temporal tunability in the volatile memristor for the reservoir layer and the nonlinearity in the nonvolatile memristor for the readout ***,integrating different types of memristors brings fabrication and integration *** overcome the challenges,a multifunctional multi-terminal electrolyte-gated transistor(MTEGT)that combines both electrostatic and electrochemical doping mechanisms is proposed in this work,integrating both widely tunable volatile dynamics with high temporal tunable range of 10^(2) and nonvolatile memory properties with high long-term potentiation/long-term depression(LTP/LTD)linearity into a single *** ion-controlled physical RC system fully implemented with only one type of MTEGT is constructed for image recognition using the volatile dynamics for the reservoir and nonvolatility for the readout ***,an ultralow normalized mean square error of 0.002 is achieved in a time series prediction *** is believed that the MTEGT would underlie next-generation neuromorphic computing systems with low hardware costs and high computational performance.

关键词： reservoir computing multi-terminal electrolyte-gated transistor ionic controlling rich dynamics nonlinear dynamical prediction

Record-Breaking Frequency of 44 GHz Based on the Higher Order Mode of Surface Acoustic Waves with LiNbO_(3)/SiO_(2)/SiC Heterostructures

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Engineering 2023年第1期20卷 112-119页

作者： Jian Zhou Dinghong Zhang yanghui liu Fengling Zhuo Lirong Qian Honglang Li Yong-Qing Fu Huigao Duan College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China Tianjin Key Laboratory of Film Electronic and Communication Devices School of Integrated Circuit Science and EngineeringTianjin University of TechnologyTianjin 30084China CAS Center for Excellence in Nanoscience National Center for Nanoscience and TechnologyBeijing 100190China Faculty of Engineering and Environment Northumbria UniversityNewcastle upon Tyne NE18STUK

Surface acoustic wave (SAW) technology has been extensively explored for wireless communication, sensors, microfluidics, photonics, and quantum information processing. However, due to fabrication issues, the frequencies of SAW devices are typically limited to within a few gigahertz, which severely restricts their applications in 5G communication, precision sensing, photonics, and quantum control. To solve this critical problem, we propose a hybrid strategy that integrates a nanomanufacturing process (i.e., nanolithography) with a LiNbO_(3)/SiO_(2)/SiC heterostructure and successfully achieve a record-breaking frequency of about 44 GHz for SAW devices, in addition to large electromechanical coupling coefficients of up to 15.7%. We perform a theoretical analysis and identify the guided higher order wave modes generated on these slow-on-fast SAW platforms. To demonstrate the superior sensing performance of the proposed ultra-high-frequency SAW platforms, we perform micro-mass sensing and obtain an extremely high sensitivity of approximately 33151.9 MHz·mm2·μg−1, which is about 1011 times higher than that of a conventional quartz crystal microbalance (QCM) and about 4000 times higher than that of a conventional SAW device with a frequency of 978 MHz.

关键词： Ultra-high frequency SAW Higher order mode Hyper sensitive detection

Personalized treatment selection via the covariate-specific treatment effect curve for longitudinal data

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Statistical Theory and Related Fields 2021年第3期5卷 253-264页

作者： yanghui liu Riquan Zhang Shujie Ma Xiuzhen Zhang School of Statistics East China Normal UniversityShanghaiPeople’s Republic of China Department of Statistics University of CaliforniaRiversideCAUSA

Treatment selection based on patient characteristics has been widely recognised in modern *** this paper,we propose a generalised partially linear single-index mixed-effects modelling strategy for treatment selection and heterogeneous treatment effect estimation in longitudinal clinical and observational *** model the treatment effect as an unknown functional curve of a weighted linear combination of time-dependent *** method enables us to investigate covariate-specific treatment effects and make personalised treatment selection in a flexible *** develop a method that combines local linear regression and penalised quasi-likelihood to estimate the weight for each covariate,the unknown treatment effect curve and the parameters for *** on pointwise confidence intervals for the treatment effect curve,we can make individualised treatment decisions from the information of patient characteristics.A simulation study is conducted to evaluate finite sample performance of the proposed *** also illustrate the method via analysis of a real data example.

关键词： personalized medicine treatment selection semiparametric model longitudinal data

A new strategy to minimize humidity influences on acoustic wave ultraviolet sensors using ZnO nanowires wrapped with hydrophobic silica nanoparticles

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Microsystems & Nanoengineering 2022年第6期8卷 73-83页

作者： Yihao Guo Jian Zhou Zhangbin Ji yanghui liu Rongtao Cao Fengling Zhuo Kaitao Tan Huigao Duan Yongqing Fu College of Mechanical and Vehicle Engineering Hunan UniversityChangshaChina Faculty of Engineering and Environment Northumbria UniversityNewcastle upon TyneUK

Surface acoustic wave(SAW)technology has been widely developed for ultraviolet(UV)detection due to its advantages of miniaturization,portability,potential to be integrated with microelectronics,and passive/wireless *** enhance UV sensitivity,nanowires(NWs),such as ZnO,are often applied to enhance SAW-based UV detection due to their highly porous and interconnected 3D network structures and good UV ***,ZnO NWs are normally hydrophilic,and thus,changes in environmental parameters such as humidity will significantly influence the detection precision and sensitivity of SAW-based UV *** solve this issue,in this work,we proposed a new strategy using ZnO NWs wrapped with hydrophobic silica nanoparticles as the effective sensing *** of the distribution and chemical bonds of these hydrophobic silica nanoparticles showed that numerous C-F bonds(which are hydrophobic)were found on the surface of the sensitive layer,which effectively blocked the adsorption of water molecules onto the ZnO *** new sensing layer design minimizes the influence of humidity on the ZnO NW-based UV sensor within the relative humidity range of 10–70%.The sensor showed a UV sensitivity of 9.53 ppm(mW/cm^(2))^(−1),with high linearity(R^(2) value of 0.99904),small hysteresis(<1.65%)and good *** work solves the long-term dilemma of ZnO NW-based sensors,which are often sensitive to humidity changes.

关键词： nanowires nanoparticles ultraviolet

Strategy to minimize bending strain interference for flexible acoustic wave sensing platform

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npj Flexible Electronics 2022年第1期6卷 820-828页

作者： Jian Zhou Zhangbin Ji Yihao Guo yanghui liu Fengling Zhuo Yuanjin Zheng Yuandong(Alex)Gu YongQing Fu Huigao Duan College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China School of Electrical and Electronical Engineering Nanyang Technological UniversitySingapore 639798Singapore Shanghai IndustrialμTechnology Research Institute(SITRI) 235 Chengbei RdShanghai 201800China Faculty of Engineering and Environment Northumbria UniversityNewcastle upon Tyne NE18STUnited Kingdom Greater Bay Area Institute for Innovation Hunan UniversityGuangzhou 511300China

There are great concerns for sensing using flexible acoustic wave sensors and lab-on-a-chip,as mechanical strains will dramatically change the sensing signals(e.g.,frequency)when they are bent during *** strain-induced signal changes cannot be easily separated from those of real sensing signals(e.g.,humidity,ultraviolet,or gas/biological molecules).Herein,we proposed a new strategy to minimize/eliminate the effects of mechanical bending strains by optimizing off-axis angles between the direction of bending deformation and propagation of acoustic waves on curved surfaces of layered piezoelectric film/flexible glass *** strategy has theoretically been proved by optimization of bending designs of off-axis angles and acoustically elastic ***-of-concept for humidity and ultraviolet-light sensing using flexible SAW devices with negligible interferences are achieved within a wide range of bending *** work provides the best solution for achieving high-performance flexible acoustic wave sensors under deformed/bending conditions.

关键词： bending wave humidity