摘要：
We propose a transfer-matrix theory to reveal the hidden structure in the multipartite nonlocality operators in one-dimensional (1D) quantum chains. The theory offers a unified description for the scaling behaviors of multipartite quantum nonlocality in general 1D quantum lattices. Furthermore, in order to figure out the hierarchy of multipartite nonlocality for infinite-size chains, powerful transfer-matrix-based algorithms are proposed. In quantum critical regions, the algorithms converge much faster than the traditional approach.
摘要：
Epitaxially orthorhombic DyMnO3 films were deposited on Nb:SrTiO3 (100) substrates by pulsed laser deposition. DyMnO3 film with weakly ferromagnetic at low temperatures, probably resulting from the strained Mn-spin configuration in the ab plane, is observed. The dielectric change under the magnetic field from 0 to 9 T at around 16 K indicates the magnet-dielectric effect, which should be related with Mn3+ spin reorientation and magneto-elastically inducing lattice modulation under DM (Dzyaloshinsky-Moriya) interaction in perovskite rare-earth manganites RMnO3.
摘要：
Urban sound event detection can automatically preload relevant information for a robot to ensure that it can be applied to various scene-activity tasks. To address the limitations of timbre similarity and scene recognition by audio collection devices, a fusion model based on the self-attention mechanism is proposed in this paper. The model consists of scattering transform and self-attention model. The scattering transform computes modulation spectrum coefficients of multiple orders through cascades of wavelet convolutions and modulus operators. It is learnable compared with Mel-scale Frequency Cepstral Coefficients (MFCC), and can be used to better restore the semantic features of some sound scenes with similar timbres. The transformer has an outstanding effect on Natural Language Processing (NLP) owing to its self-attention mechanism. In this paper, the self-attention mechanism in its encoder was used in the model, mainly to make the feature granularity consistent to refine the features. In addition, Focal Loss function was adopted in the model to curb the sample distribution imbalance. The Google Command and ESC-50 were used to supplement the scene categories of dataset UrbanSound8K. The model parameters of the learnable filters that performed well on the dataset UrbanSound8K were preserved to fine-tune the other two datasets with insufficient data volume and more target categories. The length of slice duration was further explored the in the model. The experimental results show that the model can achieve better performance in a large range of scene models.
摘要：
The operating temperature is numerically calculated and theoretically processed for the microbolometer thermal sensor array with pulse voltage bias. According to the physically thermal model and equation of heat balance for a microbolometer under a list of biasing voltage pulses, the operating temperature equation is theoretically derived for numerical calculations. Above these exact numerical calculations, the operating temperature expressed in theory is proposed for the thermal sensor in stable thermal cycles with pulse voltage bias. The theoretical expression is useful to predict the accurate infrared sensitivity of the microbolometric sensor in normal operating state, which has been proved to be exact and usable, and is feasible for being applied to the infrared sensing performance promotions of microbolometric array.
期刊：
JOURNAL OF PHYSICS-CONDENSED MATTER,2022年34(7):075801 ISSN：0953-8984
通讯作者：
Xia, ZC
作者机构：
[Xiao, Guiling] Wuhan Polytech Univ, Sch Elect & Elect Engn, Wuhan 430023, Peoples R China.;[Xia, Zhengcai; Song, Yujie] Huazhong Univ Sci & Technol, Wuhan Natl High Magnet Field Ctr, Wuhan 430074, Peoples R China.;[Xiao, Lixia] Wenhua Coll, Dept Phys Sci, Wuhan 430074, Peoples R China.
通讯机构：
[Xia, ZC ] H;Huazhong Univ Sci & Technol, Wuhan Natl High Magnet Field Ctr, Wuhan 430074, Peoples R China.
关键词：
Na2Co2TeO6;high magnetic field;spin reorientation;zigzag chain
摘要：
We investigated the magnetic characteristics of Na2Co2TeO6 at different temperatures and magnetic field. The experimental results indicated that the magnetic field can disturb the antiferromagnetic interaction and lead to the disorder. Magnetization curves measured with different angles theta (theta is between the magnetic field direction and c axis) express the magnetocrystalline anisotropy in this system. When the angle theta = 0 (magnetic field parallel to c axis), two continuous magnetic phase transitions at critical temperature T (N1) and T (N3) were observed. As theta changes, T (N1) is almost independent on theta, indicating the magnetic ordering at T (N1) was a spontaneous behavior with a robust AFM characteristic. On the other hand, as theta increases from 0 to 180, T (N3) presents extreme value at theta = 90 (magnetic field perpendicular to c axis). It indicates that T (N3) were sensitive to temperature and magnetic fields. At some angles closing to ab plane, an additional phase transition was observed at T (N2.) This phase transition at T (N2) may mainly result from the long range antiferromagnetic ordering within ab-plane. Furthermore, the magnetization measurement up to 50 T revealed the strong antiferromagnetic coupling in the system, and in which the magnetic coupling within the honeycomb layers is strong and the magnetic coupling interaction between honeycomb layers is weaker. Based on the experimental results, we have obtained the complete magnetic phase diagram.
通讯机构：
[Zhao-Yu Sun] S;School of Electrical and Electronic Engineering, Wuhan Polytechnic University, Wuhan 430023, China
摘要：
Multipartite nonlocality and Bell-type inequalities are used to characterize topological quantum phase transitions (QPTs) in a spinless fermion quantum wire, where both uniform potentials and incommensurate potentials are considered. First, the nonlocality measures show clear signals at the critical points in both the uniform model and the incommensurate model. It indicates that these QPTs are accompanied by dramatic changes of multipartite quantum correlations in the ground states. Second, finite-size scaling analysis is carried out. In particular, in the incommensurate model where translation invariance is broken, with some rescaling techniques, we successfully establish the scaling formula in the large-L limit. Finally, the full phase diagram of the model with mixed potentials is figured out. We find a region which is featured with strong randomness in the large-L limit. The structure of this region is revealed by analyzing the energy spectrum, and an efficient approach to characterize this region is proposed.
作者机构：
[Tang, Ju; Chen, Junyi; Wu, Peng; Li, Yi; Xiao, Song] School of Electrical Engineering and Automation, Wuhan University, Wuhan430072, China;[Chen, Dachang] School of electrical and electronic engineering, Wuhan Polytechnic University, Wuhan430023, China;[Zhang, Xiaoxing] Hubei Key Laboratory for High-efficiency Utilization of Solar Energy and Operation Control of Energy Storage System, Hubei University of Technology, Wuhan430068, China;[Zhang, Xiaoxing] State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing400044, China
摘要：
Ti(3)C(2)T(x) MXene is an emerging two-dimensional transition-metal carbide/nitride with excellent properties of large specific surface and high carrier mobility for room-temperature gas sensing. However, achieving high sensitivity and long-term stability of pristine Ti(3)C(2)T(x)-based gas sensors remains challenging. SnO(2) is a typical semiconductor metal oxide with high reaction activity and stable chemical properties ideal for a dopant that can comprehensively improve sensing performance. Ti(3)C(2)T(x) and SnO(2) are investigated for the first time in this study as functional materials for hybridization and room-temperature detection of the gas insulating medium fluorinated nitrile (C(4)F(7)N) with microtoxicity. A Ti(3)C(2)T(x)-SnO(2) nanocomposite sensor exhibits superior sensitivity, high selectivity, strong anti-interference ability, and excellent long-term stability. The enhanced sensing mechanism is ascribed to the synergistic effect between SnO(2) and Ti(3)C(2)T(x) and the strong adsorption ability of SnO(2) to C(4)F(7)N similar to bait for fish. We also established an actual leakage scene and demonstrated the feasibility of the Ti(3)C(2)T(x)-SnO(2) sensor to provide distribution rules with high sensing efficiency for actual engineering applications. The results of this work can expand the gas sensing application of Ti(3)C(2)T(x) MXene and provide a reference for maintaining C(4)F(7)N-based eco-friendly gas-insulated equipment.
作者机构：
[Zhang, Yunfan; Li, Hui] Wuhan Univ, Inst Technol Sci, Wuhan 430072, Peoples R China.;[Li, Hui; Wu, Kangkang; Shen, Shengnan; Han, Jinzhe] Wuhan Univ, Sch Power & Mech Engn, Wuhan 430072, Peoples R China.;[Cao, Wan] Wuhan FineMEMS Co Ltd, Wuhan 430075, Peoples R China.;[Li, Feng] Wuhan Polytech Univ, Sch Elect & Elect Engn, Wuhan 430023, Peoples R China.
通讯机构：
[Hui Li] T;The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China<&wdkj&>School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
摘要：
Thermal fatigue is one of the main causes of device failure in micro-electro-mechanical systems (MEMS). Gold wire bonding plays the role of electrical connection and signal transmission, which is the key structure of MEMS pressure sensor. In this paper, the fatigue failure of gold wire bonding solder joints caused by the thermal cycling test was studied. The thermal cycling test on MEMS pressure sensor was conducted using a temperature chamber with the cycling temperature range from -40 degrees C to 150 degrees C. After 1600 cycles, the solder joints were found with significant resistance increase to about 25 omega or even overrange value by electrical measurement. In addition, the computed tomography (CT) scanning results showed that the solder joints on the substrate underwent thermal fatigue failure and one joint was separated from the pad with a distance of 36 mu m, while the solder joints on the chip were still in good bonding conditions. The mechanism of thermal fatigue failure can be summarized as the thermal mismatch of solder joint materials, residual stress due to the bonding process, and stress concentration caused by the wedge area.
关键词：
B doping;First-principles study;Nitrogen reduction reaction (NRR);SbN monolayer;Transition-metal-free catalyst
摘要：
Electrochemical nitrogen reduction reaction (NRR) in ambient condition is an efficient and sustainable method to synthesize NH3. In this work, first-principles study was used to discuss the NRR process on B atom doped SbN monolayer. The adsorption of N-2 on B-Sb17N18 and B-S18N17 was calculated including the adsorption energy, adsorption distance, and the charge density difference (CDD). Five different reaction pathways of NRR were taken into consideration and the stability of B-SbN was investigated. The results show that, because the energy of unoccupied orbital in sp(3) hybridization of B atom is much lower than that in 2pz orbitals, the adsorption of N-2 on B-Sb18N17 shows much larger adsorption energy (-1.01 eV with end-on pattern) compared to that of the adsorption on B-Sb17N18. For five different pathways, the 1, 2, and 4 pathways have a smaller limiting potential of about 0.52 V and the limiting step is: *N-2 + H+ + e(-) -> *NNH. The 3 and 5 pathways have a larger limiting potential of 0.57 V with hydrogenation step: *NHNH2 + H+ + e(-) -> *NH2NH2. The B-Sb18N17 is structurally and thermally stable even at 500 K. Our theoretical prediction indicates that B atom substitutionally doped SbN monolayer can be a kind of high-performance metal-free NRR catalyst for NH3 synthetization, and the work provides attempts for designing and exploring 2D metal-free NRR catalysts. (C) 2021 Elsevier Inc. All rights reserved.
摘要：
MEMS capacitive accelerometer for the Internet of Things (IoT) applications is designed with open-loop structure rather than closed-loop structure to achieve low power consumption. In the open-loop structure, voltage control readout technique is preferred for low cost. However, the voltage control readout technique suffers from low dynamic range and low power efficiency (in terms of $\mathbf {FoM}$ ). In this paper, the voltage control ratiometric (VCR) readout technique is proposed to improve both dynamic range and power efficiency. The VCR readout technique is demonstrated in a readout circuit fabricated in a commercial 0.18 $\mu {\mathrm{ m}}$ 1.8V/5.0V CMOS process. Compared to the traditional voltage readout circuit fabricated with the same CMOS process and tested with the same sensing element, the VCR readout circuit improves full input signal range by $\mathbf {3.5dB}$ (from $\boldsymbol {\pm 8g}$ to $\boldsymbol {\pm 12g}$ ) and the noise floor by $\mathbf {9.5dB}$ (from $\mathrm {\mathbf {804~\mu g/}}\sqrt {\mathbf {Hz}} $ to $\mathbf {270~\mu g/}\sqrt {\mathbf {Hz}} $ ). As a result, the dynamic range is improved by $\mathbf {13.0dB}$ (from $\mathbf {44.0dB}$ to $\mathbf {57.0dB}$ ), the $\mathbf {Fo}\mathbf {M}_{\mathbf {1}}$ is improved from $\mathbf {310pJ}$ to $\mathrm {\mathbf {83pJ }}$ and the $\mathbf {Fo}\mathbf {M}_{\mathbf {2}}$ is improved from $\mathbf {1977~\mu W\cdot \mu g/Hz}$ to $\mathbf {796~\mu W\cdot \mu g/Hz}$ .
