bluuebunny/crossref_metadata_2025 huggingface dataset:
Incorporation of GTR (generation–transport–recombination) in semiconductor simulations
Authors: Muneer Sadid , Bakan Gokhan , Gokirmak Ali , Silva Helena
Published: February 2021

With the emergence of phase change memory, where the devices experience extreme thermal gradients (∼100 K/nm) during transitions between low and high resistive states, the study of thermoelectric effects at small scales becomes particularly relevant. We had earlier observed asymmetric melting of self-heated nano-crystalline silicon micro-wires, where current densities of ∼107 A/cm2 were forced through the wires by 1 μs, ∼30 V pulses. The extreme asymmetry can be explained by the generation of considerable amount of minority carriers, transport under the electric field, and recombination downstream, a heat transfer process we termed as generation–transport–recombination, which is in opposite direction of the electronic-convective heat carried by the majority carriers. Here, we present a full semiconductor physics treatment of this carrier-lattice heat transport mechanism and the contribution of the minority carriers on the evolution of the melt–solid interface, which can be applied to various high-temperature electronic devices.
Vibration wave propagation analysis of a liquid-filled pipe–plate coupled system with multiple supports
Authors: Wu Jiang-hai , Zhu Hong-zhen , Yin Zhi-yong , Sun Yu-dong
Published: February 2021

This paper analyzes the influence of an elastic plate on the vibration wave propagation of a pipe system. An impedance synthesis method is applied to establish the governing equation of the pipe–plate coupled system by using the force and boundary continuum. The natural frequency and dynamic response are determined by this method. The validity of the theoretical derivation is verified through comparisons with finite element model results. A periodically supported pipe–plate model is set up to analyze the effect of the elastic plate on the vibration bandgap. Finally, through the analysis of the vibration power flow of the coupled system, the vibration propagation characteristics of the pipe–plate configuration are analyzed from the perspective of energy flow. The results presented in this paper provide valuable suggestions for vibration control in pipe systems.
Influence of size and shape on key performance metrics in spin-torque oscillators
Authors: Zink Brandon R. , Lv Yang , Wang Jian-Ping
Published: February 2021

Spin Torque Oscillators (STOs) are promising solutions in a wide variety of next generation technologies from read-head sensors in high-density magnetic recording technology to neural oscillator units for neuromorphic computing. There are several metrics that can be used to quantify the performance of an STO such as power, quality factor, frequency tunability, etc., most of which are dependent on the design of the STO device itself. Furthermore, determining the most important metric will be contingent on its desired application, meaning that it is crucial to understand how the STOs design parameters influence all aspects of its performance so that its design can be optimized to perform the desired function. In this work, we analyzed spin torque oscillations generated from 20 magnetic tunnel junctions with in-plane anisotropy and patterned into elliptical nano-pillars with a wide range of sizes and aspect ratios. For each device, we acquired 20 to 50 data sets at various bias fields and currents and used power spectral density plots to measure output power, frequency, linewidth, quality factor, and power-to-linewidth ratio for each set. We also analyzed each STOs performance in terms of the bias fields and bias currents required to maximize output power and signal quality as well as the frequency tunability with both field and current. By comparing all of these performance metrics between the 20 STOs tested, we studied the influence of device size and shape on all aspects of STO performance and used correlation coefficients to quantify relative magnitude of these effects.
Reconsidering the Ostrogradsky theorem: higher-derivatives Lagrangians, ghosts and degeneracy
Authors: Ganz Alexander , Noui Karim
Published: February 2021

We review the fate of the Ostrogradsky ghost in higher-order theories. We start by recalling the original Ostrogradsky theorem and illustrate, in the context of classical mechanics, how higher-derivatives Lagrangians lead to unbounded Hamiltonians and then lead to (classical and quantum) instabilities. Then, we extend the Ostrogradsky theorem to higher-derivatives theories of several dynamical variables and show the possibility to evade the Ostrogradsky instability when the Lagrangian is ‘degenerate’, still in the context of classical mechanics. In particular, we explain why higher-derivatives Lagrangians and/or higher-derivatives Euler–Lagrange equations do not necessarily lead to the propagation of an Ostrogradsky ghost. We also study some quantum aspects and illustrate how the Ostrogradsky instability shows up at the quantum level. Finally, we generalize our analysis to the case of higher order covariant theories where, as the Hamiltonian is vanishing and thus bounded, the question of Ostrogradsky instabilities is subtler.
Ghost scalar field dark energy models from an extended Kaluza–Klein perspective
Authors: Korunur Murat
Published: February 2021

Reconstruction process of scalar field models (quintessence, tachyon, dilaton and K-essence), which can be performed by making use of some dark energy density definitions such as holographic, Ricci, new agegraphic and ghost types proposals, has been an interesting and very attractive area to many physicists in literature. In this work, in a five-dimensional framework, we establish a correspondence between the quintessence, tachyon and the dilaton type scalar field definitions and the generalized ghost dark energy model by considering the extended form of the Kaluza–Klein (EKK) gravity. Accordingly, we numerically study the associated equation of state parameters, as well as their kinetic energy and scalar potential terms.
Simulating quantum interference effects in the fluorescence of a V-system with perpendicular dipole moments
Authors: Crispin H B
Published: February 2021

We present a scheme that enables the observation of interference effects in the resonance fluorescence of a V-type atom with orthogonal dipole moments. Specifically, we consider the atomic configuration of a J
g = 0 to J
e = 1 transition driven by a single laser field. By employing polarization-sensitive detection in such a way that the light emitted on the two transitions become indistinguishable, we show that one can simulate the effect of vacuum-induced coherence on the resonance fluorescence of this system. In addition, we demonstrate the possibility of realizing atomic transitions with both parallel and antiparallel dipole moments and their effects on the fluorescence spectrum. The interference induced leads to interesting features in the fluorescence spectrum such as asymmetric spectral peaks, enhancement and suppression of the sidebands, and disappearance of fluorescence in the particular direction of detection. The numerical results are understood in the context of the dressed states of the combined atom–field system.
Deposition of oxygenated hydrocarbons in a packed-bed plasma reactor during the oxidation of toluene: influence of applied voltage
Authors: Mujahid Zakaulislam , Oteef Mohammed D Y , Tu Xin , Schulze Julian
Published: February 2021

Packed-bed plasma reactors (PBPRs) have been investigated extensively to study the abatement of volatile organic compounds such as toluene. Previous studies have reported that the applied voltage (or power) is a critical parameter that affects the performance of PBPRs. However, the origin of this change in performance is not well understood. A conventional PBPR contains irregularly filled dielectric pellets that generate several micro- and mesoscopic voids in between the pellets and between pellets and dielectric walls where filamentary discharges are generated. These voids are optically inaccessible and the reaction products are often generated in gaseous form; therefore, the location of the chemical reactions within these voids could not be studied. In this work, we have qualitatively investigated the influence of the applied voltage on the locations of chemical reactions in the void using toluene oxidation as an example. Using a single layer of regularly arranged hemispherical pellets and a transparent electrode in a PBPR, the plasma generation within these voids became optically accessible. The operating conditions were tailored to enhance the deposition of solid or liquid products on the glass beads to understand the locations of chemical reactions. The intensified charged coupled device camera images of the discharge through the transparent electrode show that the distribution of plasma emission changes with the applied voltage amplitude. The distribution of the deposited/condensed solid/liquid intermediates and reaction products was found to match the plasma emission. The analysis of the reaction products and deposition/condensation locations indicates that short-living species such as energetic electrons, OH and O radicals might play an essential role in the formation of deposited chemicals on the glass beads.
Investigation of mode couplings between core and cladding of terahertz anti-resonant fibres
Authors: Sun Shuai , Shi Wei , Sheng Quan , Zhang Yao , Yan Zhongbao , Zhang Junxiang , Shi Chaodu , Zhang Guizhong , Yao Jianquan
Published: February 2021

In this study, we numerically investigated mode couplings in terahertz (THz) anti-resonant fibres (ARFs) and found that the mode couplings were determined by the diameter ratio of the core and cladding tubes. Moreover, the optimal diameter ratio was affected by the change in the number of cladding tubes, bent radii and the refractive index of the gas filled in fibre. Mode couplings provide novel theories for fundamental mode suppression and higher-order mode suppression. In THz ARFs, taking the semielliptical tubes as anti-resonant elements can significantly improve the suppression ability of mode couplings.
Improving the phase stability of CsPbI3 nanocrystalline films via polyvinylpyrrolidone additive engineering for photodetector application
Authors: Yang Peixin , Ullah Saad , Wang Jiaming , Liu Linlin , Yang Shi-E , Xia Tianyu , Guo Haizhong , Chen Yongsheng
Published: February 2021

CsPbI3 perovskite materials have triggered enormous research attention as promising light-harvesting or fluorescent materials, owing to their high photoluminescence quantum yields, narrow photoluminescence (PL) emission spectra and excellent photophysical properties based on the quantum confinement effect. However, the formation of desirable black-phase CsPbI3 requires complex processing at higher annealing temperatures and upon formation it suffers from instability issues at room temperature, hindering its potential for optoelectronic application. In this work, using polyvinylpyrrolidone (PVP) as an additive, highly stable CsPbI3 nanocrystalline films are prepared at a low annealing temperature of 180 °C via a one-step spin-coating method. It is found that the PVP additive not only improves the stability by inhibiting the transition of CsPbI3 from α- to δ-phase at room temperature but also influences the crystallization dynamics. In addition, the PL intensity is substantially enhanced due to the suppression of non-recombination sites with PVP. With a PVP concentration of 12 wt%, a charge carrier lifetime of 43.99 ns is obtained and a palpable orange-yellow color is formed irradiated in plane by a green laser. Finally, a simple photodetector is fabricated with a structure of FTO/PVP-CsPbI3/Ag, exhibiting excellent photodetecting response with increased PVP concentration in the film. These results suggest that PVP-CsPbI3 has strong research and application potential in the future in optoelectronic devices.
Fabrication and investigation of quaternary Ag–In–Zn–S quantum dots-based memristors with ultralow power and multiple resistive switching behaviors
Authors: He Nan , Tao Langyi , Zhang Qiangqiang , Liu Xiaoyan , Lian Xiaojuan , Hu Er-Tao , Sheng Yang , Xu Feng , Tong Yi
Published: February 2021

Quaternary Ag–In–Zn–S (AIZS) quantum dots (QDs) play critical roles in various applications since they have advantages of combining superior optical and electrical features, such as tunable fluorescence emission and high carrier mobilities. However, the application of semiconductor AIZS QDs in brain-inspired devices (e.g. memristor) has been rarely reported. In this work, the tunable volatile threshold switching (TS) and non-volatile memory switching (MS) behaviors have been obtained in a memristor composed of AIZS QDs by regulating the magnitude of compliance current. Additionally, the innovative Ag/AIZS structure devices without traditional oxide layer exhibit low operation voltage (∼0.25 V) and programming current (100 nA) under the TS mode. Moreover, the devices achieve reproducible bipolar resistive switching (RS) behaviors with large ON/OFF ratio of ∼105, ultralow power consumption of ∼10–10 W, and good device-to-device uniformity under the MS mode. Furthermore, the charge transport mechanisms of the high- and low-resistance states under the positive and negative bias have been analyzed with space-charge-limited-current and filament conduction models, respectively. This work not only validates the potential of AIZS QDs acting as dielectric layer in RS devices but also provides a new guideline for designing ultralow power and multiple RS characteristics devices.
A systematic evaluation of learning rate policies in training CNNs for brain tumor segmentation
Authors: Bukhari Syed Talha , Mohy-ud-Din Hassan
Published: February 2021

Convolutional neural networks (CNNs) have recently emerged as a powerful approach for automatic segmentation of brain tumor subregions on 3D multi-parametric MRI scans. Learning rate is a crucial hyperparameter in the training of CNNs, impacting the performance of the learned model. Different learning rate policies trace unique trajectories in the optimization landscape that converge to local minima with varying generalization properties. In this work, we empirically evaluated nine learning rate policy-optimizer pairs with two state-of-the-art architectures, namely 2D slice-based U-Net and 3D DeepMedicRes, on an augmented brain tumor dataset of 534 subjects. Segmentation performance was quantified in terms of Dice similarity coefficient and Hausdorff distance metrics. The policies were ranked based on the final ranking score (FRS) employed by the BraTS challenge, with the statistical significance of the rankings evaluated by random permutation test. For 2D slice-based U-Net architecture, an overall ranking of learning rate policies showed that the polynomial decay policy with Adam optimizer significantly outperformed other policies for the task of individual and hierarchical segmentation of tumor subregions (p < 10−4). For 3D segment-based DeepMedicRes architecture, polynomial decay policy with Adam optimizer performed significantly better than all other policies, with the exception of polynomial decay with SGD optimizer for the same task (p < 10−4). Based on the FRS, polynomial decay policy with Adam and SGD optimizer occupied the top two positions respectively, but the difference was not statistically significant (p > 0.3). These findings were also validated on the BraTS 2019 Validation dataset which comprised of an additional 125 subjects.
Rhombohedral symmetry in GaAs1−

x
N
x
nanostructures
Authors: Zelaya-Angel O , Jiménez-Sandoval S , Alvarez-Fregoso O , Mendoza-Alvarez J G , Gómez-Herrera M L , Cardona-Bedoya J , Huerta-Ruelas J
Published: February 2021

Nanocrystalline structures of GaAs1−x
N
x
thin films were prepared on 7059 Corning glass substrates by means of an RF magnetron sputtering system using a GaAs target and N2 as ambient-gas, at several values of substrate temperature (T
s). The range of T
s was chosen from room temperature to 400 °C. The nitrogen concentration into the GaAsN layers is (1.0% ± 0.2%). The average energy band gap of the GaAsN nanostructures, calculated from their optical absorption spectra, is 2.9 ± 0.2 eV. The Raman scattering spectra exhibit vibrational modes associated to the rhombohedral phase due to the crystalline structural transformation from the zincblende (ZB)-GaAs caused by the introduction of N into the lattice. From x-ray diffraction (XRD) patterns the ZB structure was identified with two additional pairs of peaks which were associated to two types of cubic to rhombohedral crystalline phase changes of the material. One type has a low deformation to a moderately elongated unit cell, and the second type has a higher deformation to a more elongated unit cell. The rhombohedral symmetry of the crystalline lattice in the GaAsN nanostructures has been calculated from XRD data to confirm experimental evidences. The total average grain size was determined from the Scherrer formula: 3.3 ± 1.2 nm. The photoluminescence spectra are characterized by a very broad emission band which encompasses photon energies from near infrared to UV (775–310 nm, i.e. 1.6–4.0 eV).
Semi-active vibration control based on switchable transfer of bending moments: study and experimental validation of control performance
Authors: Mikułowski Grzegorz , Popławski Błażej , Jankowski Łukasz
Published: February 2021

This paper presents an experimental approach to assessment of semi-active vibration control systems based on the Prestress–Accumulation Release concept. The objectives are threefold: (1) to introduce an experimental validation method for control algorithms based on switchable transfer of moments, (2) to propose a method to assess experimentally the control effects on structural dynamic response under several types of excitation, and (3) to propose an approach for adequate sensor placement. A laboratory frame demonstrator equipped with dedicated semi-active nodes is used. The proposed approach is based on spectral responses and modal analysis. According to the presented findings, the investigated control is effective in reducing the vibration level while keeping the structural dynamic stiffness at a proper level. The investigation is conducted in the case of free response, as well as responses to impact loading and random excitation. The results confirm the accuracy of the adopted algorithm parameters and reveal the sensor locations that provide the best control effectiveness.
Frequency dependent wave routing based on dual-band valley-Hall topological photonic crystal
Authors: Wei Guo-Chao , Liu Zhen-Zhen , Zhang Da-Sen , Xiao Jun-Jun
Published: February 2021

Previous studies on the propagation direction of valley topological edge states mainly focus on the matching between orbital angular momentum of the excitation source and specific pseudo-spin state of valley edge mode at certain frequency that falls in the bandgap of the topologically distinct bulk components. In this work, we propose topological photonic crystals (PCs) hosting two topological protected bandgaps. It is shown that by constructing the interface between different PC structures with distinct topological phase, edge states can be engineered inside these two bandgaps, which provides a convenient way to achieve flexible wave routing. Particularly, we study three types of meta-structures consisting of these PCs in which the valley edge states routing path highly depends on the operating frequency and inputting port of the excitation source. Our study provides an alternative way in designing topological devices such as wave splitters and frequency division devices.
Probing band-center anomaly with the Kernel polynomial method
Authors: Khan N A , Amin Syed Tahir
Published: February 2021

We investigate the anomalous behavior of localization length of a non-interacting one-dimensional Anderson model at zero temperature. We report numerical calculations of the Thouless expression of localization length, based on the Kernel polynomial method (KPM), which has an


(
N
)

computational complexity, where N is the system size. The KPM results show excellent agreement with perturbative results in a large system size limit, confirming the validity of the Thouless formula. In the perturbative regime, we show that the KPM approximation of the Thouless expression produces the correct localization length at the band center in the thermodynamic limit. The Thouless expression relates localization length in terms of density of states in a one-dimensional disordered system. By calculating the KPM estimates of the density of states, we find a cusp-like behavior around the band center in the perturbative regime. This cusp-like singularity can not be obtained by approximate analytical calculations within the second-order approximations, reflects the band-center anomaly.
Impact of magnetic dipole on ferromagnetic hybrid nanofluid flow over a stretching cylinder
Authors: Kumar R Naveen , Gowda R J Punith , Abusorrah Abdullah M , Mahrous Y M , Abu-Hamdeh Nidal H , Issakhov Alibek , Rahimi-Gorji Mohammad , Prasannakumara B C
Published: February 2021

Nanofluids manage heat in the internal combustion of the engines or machines by avoiding corrosion in the cooling system as well as assist in eradicating the engine’s waste heat. Hence, they are used as coolants in many automotive industries. Inspired by these applications, the thermal and mass transfer in hybrid nanoliquid flow over a stretching cylinder on taking account of magnetic dipole is studied in this investigation. Here, we have done a comparative study on flow of two diverse combinations of hybrid nanofluids, namely

MnZnFe

2

O

4

−

NiZnFe

2

O

4

−

C

10

H

22

and

Cu
−

Al

2

O

3

−

C

10

H

22

.

The modelled equation for the assumed flow is converted to ODEs by opting appropriate similarity variables. These ODEs are solved by utilizing the Runge–Kutta Fehlberg fourth-fifth order (RKF-45) method by adopting shooting technique. Physical clarification of relevant parameters for non-dimensional discrete flow fields are discussed briefly by using graphs. Also, skin friction, Sherwood and Nusselt numbers are deliberated with the assistance of graphs. Results reveal that, the upsurge in ferromagnetic interaction parameter declines the velocity in both fluids but converse trend is detected in temperature and concentration of the liquids. The heightening of ferromagnetic interaction parameter declines the rate of heat and mass transfer.
The electromagnetic waves propagating parallel to the magnetic field in a uniform magnetized plasma with a transverse electric field
Authors: Zhou Deng , Ming Yue , Wang Jinfang , Gan Chenxiao
Published: February 2021

In natural and laboratory magnetized plasmas, an equilibrium electric field may exist perpendicular to the background magnetic field. In such a situation all the plasma species experience a common drift and the equilibrium distribution functions have a common shift in velocity space. The susceptibility tensor is derived for such a situation using the characteristics and then the Lorentz transformation method is adopted to verify the results. As an application we give an analysis of the waves propagating parallel to the background magnetic field for a simple electron plus single charged ion plasma. It is predicted that the presence of a transverse equilibrium electric field can drastically change the wave propagation only if the wave frequency is close to the plasma Langmuir frequency.
A super-junction SOI-LDMOS with low resistance electron channel
Authors: Chen Wei-Zhong , Huang Yuan-Xi , Huang Yao , Huang Yi , Han Zheng-Sheng
Published: February 2021

A novel super-junction LDMOS with low resistance channel (LRC), named LRC-LDMOS based on the silicon-on-insulator (SOI) technology is proposed. The LRC is highly doped on the surface of the drift region, which can significantly reduce the specific on resistance (R
on,sp) in forward conduction. The charge compensation between the LRC, N-pillar, and P-pillar of the super-junction are adjusted to satisfy the charge balance, which can completely deplete the whole drift, thus the breakdown voltage (BV) is enhanced in reverse blocking. The three-dimensional (3D) simulation results show that the BV and R
on,sp of the device can reach 253 V and 15.5 mΩ ⋅ cm2, respectively, and the Baliga’s figure of merit (FOM = BV
2/R
on,sp) of 4.1 MW/cm2 is achieved, breaking through the silicon limit.
Research on the ions’ axial temperature of a sympathetically-cooled 113Cd+ ion crystal*
Authors: Xin Nong-Chao , Miao Sheng-Nan , Qin Hao-Ran , Guo Li-Ming , Han Ji-Ze , Hu Hua-Xing , Shi Wen-Xin , Zhang Jian-Wei , Wang Li-Jun
Published: February 2021

Molecular dynamics simulation of a sympathetically-cooled 113Cd+ ion crystal system is achieved. Moreover, the relationship between ions’ axial temperature and different electric parameters, including radio frequency voltage and end-cap voltage is depicted. Under stable trapping condition, optimum radio frequency voltage, corresponding to minimum temperature and the highest cooling efficiency, is obtained. The temperature is positively correlated with end-cap voltage. The relationship is also confirmed by a sympathetically-cooled 113Cd+ microwave clock. The pseudo-potential model is used to illustrate the relationship and influence mechanism. A reasonable index, indicating ions’ temperature, is proposed to quickly estimate the relative ions’ temperature. The investigation is helpful for ion crystal investigation, such as spatial configuration manipulation, sympathetic cooling efficiency enhancement, and temporal evolution.
Temporal and spatial chaos in the Kerr-AdS black hole in an extended phase space *
Authors: Tang Bing
Published: February 2021

Based on the Melnikov method, we investigate chaotic behaviors in the extended thermodynamic phase space for a slowly rotating Kerr-AdS black hole under temporal and spatial perturbations. Our results show that the temporal perturbation coming from a thermal quench of the spinodal region in the phase diagram may cause temporal chaos only when the perturbation amplitude is above a critical value, which involves the angular momentum J. Under the spatial perturbation, however, it is found that spatial chaos always occurs, independent of the perturbation amplitude.
Improving the performance of multisubject motor imagery-based BCIs using twin cascaded softmax CNNs
Authors: Luo Jing , Shi Weiwei , Lu Na , Wang Jie , Chen Hao , Wang Yaojie , Lu Xiaofeng , Wang Xiaofan , Hei Xinhong
Published: February 2021

Objective. Motor imagery (MI) EEG signals vary greatly among subjects, so scholarly research on motor imagery-based brain–computer interfaces (BCIs) has mainly focused on single-subject systems or subject-dependent systems. However, the single-subject model is applicable only to the target subject, and the small sample number greatly limits the performance of the model. This paper aims to study a convolutional neural network to achieve an adaptable MI-BCI that is applicable to multiple subjects. Approach. In this paper, a twin cascaded softmax convolutional neural network (TCSCNN) is proposed for multisubject MI-BCIs. The proposed TCSCNN is independent and can be applied to any single-subject MI classification convolutional neural network (CNN) model. First, to reduce the influence of individual differences, subject recognition and MI recognition are accomplished simultaneously. A cascaded softmax structure consisting of two softmax layers, related to subject recognition and MI recognition, is subsequently applied. Second, to improve the MI classification precision, a twin network structure is proposed on the basis of ensemble learning. TCSCNN is built by combining a cascaded softmax structure and twin network structure. Main results. Experiments were conducted on three popular CNN models (EEGNet and Shallow ConvNet and Deep ConvNet from EEGDecoding) and three public datasets (BCI Competition IV datasets 2a and 2b and the high-gamma dataset) to verify the performance of the proposed TCSCNN. The results show that compared with the state-of-the-art CNN model, the proposed TCSCNN obviously improves the precision and convergence of multisubject MI recognition. Significance. This study provides a promising scheme for multisubject MI-BCI, reflecting the progress made in the development and application of MI-BCIs.
Resource allocation method based on mobile edge computing in smart grid
Authors: Qin Ningli , Li Bo , Li Da , Jing Xiaosong , Du Changyu , Wan Chunyi
Published: February 2021

Mobile edge computing(MEC) refers to offloading the collected data to the mobile edge server, which can calculate data efficiently, further improve the operating efficiency of the smart grid and reduce energy consumption. In the face of increasing data, the spectrum overhead and energy consumption of the network are becoming increasingly severe. Based on this, this paper proposes to use massive multiple input multiple output (MIMO) technology to improve the spectrum and energy efficiency of the system, and proposes a massive MIMO-MEC smart grid system framework. In addition, considering that it is easy to be eavesdropped in the process of offloading data, we propose to use physical layer security technology to ensure user information security. In order to minimize the energy consumption of applications such as smart meters, this paper proposes a sequential iterative optimization algorithm to jointly optimize the offloading rate and transmission power. The simulation results prove that as the number of antennas increases, the transmission rate of the system increases, which reduces the total energy consumption of the system.
Numerical simulation of scale deposition in boiler water wall with different structures
Authors: xing Wu , yangyan Zheng , yining Wang , chuanyang Xie
Published: February 2021

The scale produced by the boiler water wall will affect the heat exchange and shorten its service life. In this paper, based on the Euler-Lagrangian method, the numerical simulation of the accretion rate of the water wall under different dip angles and different flow conditions is carried out. In this paper, the accretion rate is almost power-distributed with the dip angles. From 0° to 60°, accretion rate from 6.55×10”2kg/m2.-s increases to 0.38kg/m2.-s As the Re number increases from about 6×104 to 7×104, the accretion rate declines rapidly and then flattens out. Compared with dip Angle, the influence of velocity on accretion rate is less.
Eigensensitivitity analysis of large-scale structures by substructuring method
Authors: Song Xiaodong , Weng Shun , Yang Guojing , Yan Yongyi , Li Jiajing
Published: February 2021

In sensitivity-based model updating, the eigensolutions and the associated derivatives of the analytical model need to be calculated iteratively to achieve an optimal solution, which is very time-consuming for a large-scale structure. To overcome this shortcoming, this paper proposes a new method to calculate the eigensensitivity via substructuring approach. When the design parameters in one particular substructure need to update, the sensitivity matrices to the updating parameters at this substructure are calculated while they are zeros at other substructures. The eigensensitivity at the global level is assembled by performing some constraints on the sensitivity matrices at the substructure level. The proposed method is applied in a frame and a practical bridge structure. Numerical results show that the present substructuring approach is more efficient than the traditional global method, at the satisfactory precision.
Experiment study of vibration isolation by multi-rows of piles
Authors: Wang Zhiying , Gui Zunyao , Meng Qingjuan
Published: February 2021

Pile barriers have been broadly used to decrease the effect of ground vibration generated by machines or traffic. However, so far, the research about the model test of vibration isolation of pile barriers is very few. In the present paper, the basic properties of the soil in the concrete model box are determined by the basic properties test of the soil firstly. Secondly, through the model tests with two types of piles under different vibration frequencies, the influences of different factors on the vibration isolation effect of pile barriers are studied. The results show that the multi-row pile barriers can effectively isolate the vibration. The main factors influencing the isolation effect are the pile diameter, the number of rows of piles and the vibration wave frequency.
Vibration characteristics and vibration isolation design of oil-immersed power transformer
Authors: Qian Zhijie , Cao Meigen , Ying Jianlie , Zhuang Weide , Zhang Hong , Shi Jin , Zhou Dongcheng
Published: February 2021

Transformer vibration and noise has become a prominent problem in power grid construction and operation. Firstly, on the basis of expounding the vibration mechanism of iron core and winding, the transmission path of vibration and noise of transformer is analyzed. Secondly, it is pointed out that it is not cost-effective to control transformer vibration and noise only from the selection of core and winding materials, manufacturing process and structural optimization. It is necessary to start from the transmission path of transformer sound and vibration, and adopt auxiliary vibration reduction and noise reduction measures such as vibration isolation of the body to reduce the transmission of vibration of the body to the oil tank wall, foundation and adjacent structures. Then, the design method of oil immersed power transformer body vibration isolation is discussed, and the relevant parameters such as frequency ratio, damping ratio and the arrangement of vibration isolation support are proposed. The reasonable vibration isolation design of transformer body can achieve remarkable vibration isolation effect and the vibration isolation efficiency can reach more than 96%. Finally, the vertical design stiffness of 81 kinds of oil immersed power transformer vibration isolation layers with 4 voltage levels of 10 kV, 35 kV, 110 kV and 220 kV are calculated. Taking a typical 110 kV transformer as an example, the corresponding vibration isolation design scheme is proposed. The research provides a good reference for the vibration isolation design of transformer body in the future.
HMM speech recognition study of an Improved Particle Swarm Optimization Based on Self-Adaptive Escape (AEPSO)
Authors: Liangpan Ye , Tao He
Published: February 2021

Aiming at the single evaluation content of the current train simulation training system, the process of voice interaction in the daily work of train conductors cannot be effectively and comprehensively reflected, and the coordination between dispatching terminology and train running equipment are not considered. In order to realize the objective evaluation of whether the terms are clear and the semantics accurate and the consistency check of “schedule terms-equipment operation”, the HMM speech recognition subsystem of an Improved Particle Swarm Optimization Based on Self-Adaptive Escape (AEPSO) for railway dispatching was constructed. Compared with the traditional Baum-Welch algorithm, the experiment result shows that AEPSO-BW algorithm has certain advantages in speech recognition compared with traditional Baum-Welch algorithm. It provides a more comprehensive evaluation index for the training and assessment of vehicle service personnel.
BIM-based ventilation shaft construction schedule simulation and plan optimization
Authors: Shen Jiao , Wu Qing , Peng Chen , Zhao Suya
Published: February 2021

In order to solve the problems of multiple construction links, mutual influence and restriction, and tight construction period of the ventilation shaft under complex geological conditions, the BIM technology is used to realize the three-dimensional parametric modeling of the Nanhu ventilation shaft project from geology, main structure and main construction equipment, etc. Simulating the construction schedule, formulating a reasonable schedule and optimizing the construction plan are of great significance for accelerating the construction schedule, controlling construction risks, and striving to make the Nanhu air shaft project put into use as soon as possible.
Dynamic Analysis of Seventh-Class ColumnFrame with Cushion
Authors: Yang Songye , Wang Jianliang , Wang Yifan , Li Tieying
Published: February 2021

In accordance with the relevant regulations of Building Method, this paper uses the finite element model to establish a two-column seven-grade dovetail column frame model. 4 kinds of thin cushions are designed with different elasticity and shear modulus at the bottom of the column. The elastic modulus of the cushion is 1/5, 1/10, 1/15, 1/30 of the column frame modulus. A simple harmonic wave with an amplitude of 50 gal and a frequency of 1Hz-2.5Hz was applied to the wooden frame model with cushion and without cushion. There are a total of 20 models and their natural vibration period is obtained and the relative displacement time history curve of the top of the column was extracted to obtain the displacement angle between each model. The results show that: the natural vibration period of the wooden frame with cushion is greater than that without cushion, and the period increases with the decrease of the elastic modulus of the cushion. As the harmonic frequency increases, the layer displacement angle of each wood frame model decreases, and as the cushion modulus decreases, the decreasing amplitude becomes more gentle, indicating that the cushioned wood structure has better resistance to deformation.
Effect of Alternating Electromagnetic Activated Water on Properties of Cement Mortar
Authors: Zhang Zhifeng , Li Borong , Song Nan , Zhao Lei
Published: February 2021

For cement mixture, water is indispensable and directly affects the performance of cement mixture of raw materials. Based on the research conclusion of alternating electromagnetic field, square wave excitation signal and 50-turn excitation coil were used to activate water through alternating electromagnetic field with different magnetic induction intensity (52.6mT, 97.8mT, 151.2mT, 193.6mT) at different flow rates (0.69m/s, 0.85m/s, 1.05m/s) to explore the effect of activated water on the performance of cement mortar. Through tests, the workability and compressive strength of cement mortar are improved, the water retention is better, and the apparent density is increased. The maximum increase of consistency is 34%, the layering degree is within 20mm, and the compressive strength of 7th day, 14th day and 28th day can be increased by 27.5%, 23.8% and 20.3%.
Health For You
Authors: Surapur Pooja , Reddy Vishnu Preetham , Hussain Munavar , Satya Kumar C
Published: February 2021

Health for you is an application which acts like interface between patients and doctors. All the patients can fill the application regarding the disease they had been suffering with. Any doctor who is interested in serving people for free can register using their license during the sign up process and give solution to the patient’s disease. The doctor can examine the patient’s details, write the prescription or second opinion and mail it to the patient. The problem was to create an application which efficiently does one of the most strenuous and huge tasks like connecting poor people with well experienced doctors at free of cost and gain very valuable suggestions. Finally, the app should act like a natural hospital where the treatment is available free of cost from your living room. To avoid certain doubts to our doctors we have made a bunch of clarifications to our patients and users that we validate for a unique like license of doctor and make a search in our national database we register him as a doctor after having some typical steps of registration.
High and Low Temperature Resistance of Phenyl silicone rubber
Authors: Huang Yanhua , Mu Qiuhong , Su Zhengtao
Published: February 2021

Methyl Phenyl and diphenyl silicone rubbers were synthesized from octamethyl cyclotetrasiloxane (D4), methylphenyl cyclosiloxane, octaphenyl cyclotetrasiloxane, etc. Compared with the commercial methylvinyl silicone rubber, the high and low temperature resistances of methyl vinyl silicone rubber were studied in this paper. The results showed that the introduction of phenyl groups can improve the thermal properties of silicone rubber, and the thermal stability of diphenyl silicone rubber is better than that of methyl phenyl silicone rubber. But there is little difference of mechanical properties in high temperature environment for three silicone rubber. DMTA analysis showed that there were still a small amount of crystals in diphenyl silicone rubber, while methylphenyl silicone rubber was amorphous rubber. The mechanical properties at low temperature indicated that the tensile strength of diphenyl silicone rubber was 4.1Mpa higher than that of methylphenyl silicone rubber at -70 °C due to the existence of low-temperature crystallization.
Preparation and characterization of magnetic α-Fe2O3/Fe3O4 heteroplasmon nanorods via the ethanol solution combustion process of ferric nitrate
Authors: Yang Xigang , Jin Baosheng , Yu Lulu , Zhu Fahua , Xu Yueyang , Liu Ruijiang
Published: February 2021

An ethanol solution combustion process of ferric nitrate for preparing magnetic α-Fe2O3/Fe3O4 heteroplasmon nanorods was introduced. The influencing factors, including the solvent type and the calcination conditions, were discussed. Anhydrous ethanol was considered to be the most suitable solvent for the preparation of α-Fe2O3/Fe3O4 heteroplasmon nanorods, and the optimal calcination time was determined to be 2 h. By changing the calcination temperature, α-Fe2O3/Fe3O4 heteroplasmon nanorods with different phase compositions could be obtained, and the mechanism was explained in detail. The results indicated that the rapid combustion method could achieve the controlled preparation of α-Fe2O3/Fe3O4 heteroplasmon nanorods, which provided a general preparation approach for α-Fe2O3/Fe3O4 heteroplasmon nanomaterials.
Synthesizing CT images from MR images with deep learning: model generalization for different datasets through transfer learning
Authors: Li Wen , Kazemifar Samaneh , Bai Ti , Nguyen Dan , Weng Yaochung , Li Yafen , Xia Jun , Xiong Jing , Xie Yaoqin , Owrangi Amir , Jiang Steve
Published: February 2021

Background and purpose. Replacing CT imaging with MR imaging for MR-only radiotherapy has sparked the interest of many scientists and is being increasingly adopted in radiation oncology. Although many studies have focused on generating CT images from MR images, only models on data with the same dataset were tested. Therefore, how well the trained model will work for data from different hospitals and MR protocols is still unknown. In this study, we addressed the model generalization problem for the MR-to-CT conversion task. Materials and methods. Brain T2 MR and corresponding CT images were collected from SZSPH (source domain dataset), brain T1-FLAIR, T1-POST MR, and corresponding CT images were collected from The University of Texas Southwestern (UTSW) (target domain dataset). To investigate the model’s generalizability ability, four potential solutions were proposed: source model, target model, combined model, and adapted model. All models were trained using the CycleGAN network. The source model was trained with a source domain dataset from scratch and tested with a target domain dataset. The target model was trained with a target domain dataset and tested with a target domain dataset. The combined model was trained with both source domain and target domain datasets, and tested with the target domain dataset. The adapted model used a transfer learning strategy to train a CycleGAN model with a source domain dataset and retrain the pre-trained model with a target domain dataset. MAE, RMSE, PSNR, and SSIM were used to quantitatively evaluate model performance on a target domain dataset. Results. The adapted model achieved best quantitative results of 74.56 ± 8.61, 193.18 ± 17.98, 28.30 ± 0.83, and 0.84 ± 0.01 for MAE, RMSE, PSNR, and SSIM using the T1-FLAIR dataset and 74.89 ± 15.64, 195.73 ± 31.29, 27.72 ± 1.43, and 0.83 ± 0.04 for MAE, RMSE, PSNR, and SSIM using the T1-POST dataset. The source model had the poorest performance. Conclusions. This work indicates high generalization ability to generate synthetic CT images from small training datasets of MR images using pre-trained CycleGAN. The quantitative results of the test data, including different scanning protocols and different acquisition centers, indicated the proof of this concept.
Review on Ruddlesden–Popper perovskites as cathode for solid oxide fuel cells
Authors: Ding Peipei , Li Wenlu , Zhao Hanwen , Wu Congcong , Zhao Li , Dong Binghai , Wang Shimin
Published: February 2021

Solid oxide fuel cells (SOFC) are highly efficient energy conversion device, but its high operating temperature (800∼1000 °C) restricts industrial commercialization. Reducing the operating temperature to <800 °C could broaden the selection of materials, improve the reliability of the system, and lower the operating cost. However, traditional perovskite cathode could not both attain the high catalytic activity towards the oxygen reduction reaction and good durability at medium and low temperature range. In contrast to the conventional perovskites, Ruddlesden–Popper perovskites exhibit fast oxygen surface exchange kinetic and excellent stability at medium and low temperatures, and excel both in oxide-conducting fuel cells (O-SOFC) and proton-conducting fuel cells (H-SOFC). In this paper, we try to relate its prominent performance with the crystal structure, main physical properties, and transport mechanism of oxygen ions and protons. We also summarize the current strategy in improving its application in O-SOFC and H-SOFC. Finally, we discuss the challenges and outlook for the future development of RP perovskites in SOFC.
Photonic pattern reconstruction enabled by on-chip online learning and inference
Authors: Marquez Bicky A , Guo Zhimu , Morison Hugh , Shekhar Sudip , Chrostowski Lukas , Prucnal Paul , Shastri Bhavin J
Published: February 2021

Recent investigations in neuromorphic photonics exploit optical device physics for neuron models, and optical interconnects for distributed, parallel, and analog processing. Integrated solutions enabled by silicon photonics enable high-bandwidth, low-latency and low switching energy, making it a promising candidate for special-purpose artificial intelligence hardware accelerators. Here, we experimentally demonstrate a silicon photonic chip that can perform training and testing of a Hopfield network, i.e. recurrent neural network, via vector dot products. We demonstrate that after online training, our trained Hopfield network can successfully reconstruct corrupted input patterns.
Thick Fibrous Septa on Liver Biopsy Specimens Predict the Development of Decompensation in Patients With Compensated Cirrhosis
Authors: Jain Dhanpat , Sreenivasan Prithvi , Inayat Irteza , Deng Yanhong , Ciarleglio Maria M , Garcia-Tsao Guadalupe
Published: February 2021

Objectives

In compensated cirrhosis, thick fibrous septa and small nodules on liver biopsy specimens correlate with the presence of clinically significant portal hypertension (CSPH). In turn, CSPH is the strongest predictor of cirrhosis decompensation. The aim of the study was to correlate liver biopsy specimen characteristics with the development of decompensation in patients with compensated cirrhosis.

Methods

Patients with compensated cirrhosis and a concurrent liver biopsy specimen were reviewed. Semiquantitative grading of septal thickness and nodule size was performed. Primary end point was development of clinical decompensation. In total, 168 patients (median age, 49 years; 76% men) were included in the study; the most common etiology was viral.

Results

In a median follow-up of 50 months, 43 (26%) patients developed clinical decompensation (60% ascites, 16% encephalopathy, 12% variceal hemorrhage, 7% jaundice, and 5% mixed). On univariate analysis, septal width was significantly associated with decompensation, but nodule size was not. On multivariate analysis including model for end-stage liver disease score, serum albumin, and septal width, albumin and septal width were independent predictors of decompensation.

Conclusions

Histologic cirrhosis in compensated patients can be subclassified by severity based on septal thickness, with thick septa denoting worse prognosis.