bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical and optical modeling of gap-free III-nitride micro-LED arrays
Authors: Noor Elahi Asim M. , Xu Jian
Published: October 2020

Ion implantation-fabrication of gap-free III-nitride micro-light emitting diode (μLED) arrays has been analyzed along with its impacts on micro-LED electrical and optical characteristics. The implanted ions were designed to block the current between the adjacent pixels in the micro-LED array for gap-free isolation. Electrical simulation suggests that the crosstalk current among the pixels depends on three key parameters, i.e., ion energy, ion dose, and the width of the isolation barrier. The ion implantation parameters used in the simulation were chosen from previous published reports to provide some insights of the follow up experimental study of this work. The electrical crosstalk can be reduced by the increase in the impurity concentration in the isolation barriers, which introduces more deep level traps that impede the lateral current low between the pixels in the array. The optical simulation results show that the gap-free configuration of the pixelated micro-LEDs also suppresses the light crosstalk caused by the wave-guide effect substantially. Studying the electrical and optical crosstalk performance of gap-free micro-LED arrays could pave the way for developing LED-based microdisplay panels with ultra-small pitch dimensions and low crosstalk noises, both of which are essential for high display resolutions.
Caffeine modulates the dynamics of DODAB membranes: Role of the physical state of the bilayer
Authors: Sharma V. K. , Srinivasan H. , García Sakai V. , Mitra S.
Published: October 2020

Caffeine (1,3,7-trimethylxanthine), an ingredient of coffee, is used worldwide as a psychostimulant, antioxidant, and adjuvant analgesic. To gain insights into the action mechanism of caffeine, we report on its effects on the microscopic dynamics of a dioctadecyldimethylammonium bromide lipid membrane, as studied using quasielastic neutron scattering. Caffeine significantly modulates the microscopic dynamics of the lipids in the system, and the effects depend on the lipid phase. In the coagel phase, caffeine acts as a plasticizing agent, whereas in the fluid phase, it restricts the lateral and internal motions of the lipids. The present study illustrates how caffeine regulates the fluidity of the membrane by modulating the dynamics of constituent lipids depending on the physical state of the bilayer.
Experimental simulation of stratospheric ozone reactions with chloroalkane organic pollutants
Authors: Savilov Serguei V. , Strokova Natalia E. , Ivanov Anton S. , Morozov Igor I.
Published: October 2020

Environmental contextChlorinated organic atmospheric pollutants, which can be produced naturally or anthropogenically, are considered as a factor responsible for stratospheric ozone depletion. Based on experimental simulations and low temperature vibrational spectroscopy, this work reports a mechanism for the reaction of chloroalkanes with ozone. This reaction leads to the formation of the photochemically reactive chlorine oxide species. Kinetics and implications of the reactions are discussed.
AbstractThe present work deals with the important problem of stratospheric ozone depletion and an investigation of the atmospheric decay of organic pollutants. The products of the heterogeneous reactions of ozone with chloroethane and 1-chloropropane in a flow-through vacuum electric discharge unit under conditions similar those observed in the stratosphere are studied by low-temperature infrared (IR) absorption spectroscopy. Taking into account the literature data, a scheme for the interaction of ozone with halogen-substituted alkanes at low temperatures is proposed, which shows the formation of chlorine oxides that have high photochemical activity and can cause damage to the ozone layer even when present in small concentrations. The conversion of chloroalkanes over time demonstrates the first-order-decay behaviour of the investigated processes.
Vulnerability assessment of marine economic system based on comprehensive index and catastrophe progression model
Authors: Gao Sheng , Sun Huihui , Ma Miaosen , Lu Yanyan , Yao Yuan , Liu Wei
Published: October 2020

The sustainable development of the marine economic system to accurately grasp the dynamic evolution characteristics and main driving factors of the vulnerability of the marine economic system so as to effectively identify the problems in the operation of the marine economy is extremely important. Based on the establishment of a three-level assessment index system for the vulnerability of the marine economic system, the vulnerability of the marine economic system of Jiangsu Province in 2008–2016 was evaluated by using the comprehensive index model and the catastrophe progression model, and the results were compared based on the unified evaluation criteria. The main influencing factors were analyzed by principal component analysis and Pearson correlation analysis. It’s found that 2014, 2015, and 2012 are in a general state, 2009 and 2010 are in a poor state, and the vulnerability state from 2008 to 2011 is lower than that in 2012. The overall volatility is small indicating a stable system. Among them, the scale of marine industry and profit and loss of marine resources are the main components of marine economic system vulnerability having the highest correlation with the vulnerability of marine economic system. This study enriches the theoretical method and empirical research on the vulnerability of the marine economic system and has practical significance in allowing for timely targeted control measures to affect the vulnerability of the marine economic system.
Mechanisms and dynamics of the NH+
2 + H+ and NH+ + H+ + H fragmentation channels upon single-photon double ionization of NH3
Authors: Larsen Kirk A , Rescigno Thomas N , Streeter Zachary L , Iskandar Wael , Heck Saijoscha , Gatton Averell , Champenois Elio G , Severt Travis , Strom Richard , Jochim Bethany , Reedy Dylan , Call Demitri , Moshammer Robert , Dörner Reinhard , Landers Allen L , Williams Joshua B , McCurdy C William , Lucchese Robert R , Ben-Itzhak Itzik , Slaughter Daniel S , Weber Thorsten
Published: October 2020

We present state-selective measurements on the

N
H

2

+

+ H+ and NH+ + H+ + H dissociation channels following single-photon double ionization at 61.5 eV of neutral NH3, where the two photoelectrons and two cations are measured in coincidence using 3D momentum imaging. Three dication electronic states are identified to contribute to the

N
H

2

+

+ H+ dissociation channel, where the excitation in one of the three states undergoes intersystem crossing prior to dissociation, producing a cold

N
H

2

+

fragment. In contrast, the other two states directly dissociate, producing a ro-vibrationally excited

N
H

2

+

fragment with roughly 1 eV of internal energy. The NH+ + H+ + H channel is fed by direct dissociation from three intermediate dication states, one of which is shared with the

N
H

2

+

+ H+ channel. We find evidence of autoionization contributing to each of the double ionization channels. The distributions of the relative emission angle between the two photoelectrons, as well as the relative angle between the recoil axis of the molecular breakup and the polarization vector of the ionizing field, are also presented to provide insight on both the photoionization and photodissociation mechanisms for the different dication states.
Holes in Bayesian statistics
*
Authors: Gelman Andrew , Yao Yuling
Published: October 2020

Every philosophy has holes, and it is the responsibility of proponents of a philosophy to point out these problems. Here are a few holes in Bayesian data analysis: (1) the usual rules of conditional probability fail in the quantum realm, (2) flat or weak priors lead to terrible inferences about things we care about, (3) subjective priors are incoherent, (4) Bayesian decision picks the wrong model, (5) Bayes factors fail in the presence of flat or weak priors, (6) for Cantorian reasons we need to check our models, but this destroys the coherence of Bayesian inference. Some of the problems of Bayesian statistics arise from people trying to do things they should not be trying to do, but other holes are not so easily patched. In particular, it may be a good idea to avoid flat, weak, or conventional priors, but such advice, if followed, would go against the vast majority of Bayesian practice and requires us to confront the fundamental incoherence of Bayesian inference. This does not mean that we think Bayesian inference is a bad idea, but it does mean that there is a tension between Bayesian logic and Bayesian workflow which we believe can only be resolved by considering Bayesian logic as a tool, a way of revealing inevitable misfits and incoherences in our model assumptions, rather than as an end in itself.
DNA-inspired frequency reconfigurable origami antenna using segmented rotation technique
Authors: Shah Syed Imran Hussain , Lim Sungjoon
Published: October 2020

This article proposes a DNA inspired mechanically transformable frequency reconfigurable origami antenna. Further, the implementation of segmented rotation technology enables the folding-unfolding feature of the DNA inspired geometry. The tuning range of 145% with wide frequency sweep from 0.395 to 2.5 GHz is achieved for the proposed antenna. The proposed origami antenna was fabricated on a robust polyethylene terephthalate (PET) substrate, realizing the antenna conductive pattern using copper film. The reflection coefficients and radiation patterns of the fabricated antenna sample were measured for unfolded, partially folded, and completely folded states. The proposed origami antenna provides flexible design, efficient folding, compact packaging, and simple deployment.
Synchronously-pumped, all-solid-state, picosecond Raman laser at 1169 and 1222 nm on single and combined Raman modes in a Ca3(VO4)2 crystal with 30-times pulse shortening down to 1.2 ps
Authors: Frank M , Smetanin S N , Jelínek Jr M , Vyhlídal D , Ivleva L I , Dunaeva E E , Voronina I S , Shukshin V E , Zverev P G , Kubeček V
Published: October 2020

An all-solid-state extracavity synchronously pumped Ca3(VO4)2 Raman laser on broadened stretching (854 cm−1) and bending (354 cm−1) Raman modes with efficient stimulated Raman scattering (SRS) conversion at single frequency shift and the strongest 30-times pulse shortening down to 1.2 ps at combined frequency shift is demonstrated. The antireflection-coated, 78 mm long, a-cut Ca3(VO4)2 crystal was used as an active element under synchronous pumping by the 330 nJ, 1063 nm, 36 ps, 150 MHz mode-locked Nd:GdVO4 laser. SRS oscillation with slope efficiency of 34.2% and conversion of 18.5% at the wavelength of 1169 nm of the 854 cm−1-shifted first Stokes component with the pulse duration of 31 ps and output energy of up to 61 nJ in the external ring cavity with the output coupler reflectivity of 87% has been obtained. In the case of the second setup with high cavity Q-factor for the wavelength of 1169 nm, the additional cascade SRS component at 1222 nm with combined (854 cm−1 + 354 cm−1) frequency shift was observed. This component was generated with the slope efficiency of 8.1% and the output energy of 14.2 nJ with the output coupler reflectivity of 95%. Due to dynamics of SRS build-up in synchronously pumped extracavity Raman laser, the strongest pulse shortening at 1222 nm was achieved. The shortest pulse duration of 1.27 ps was measured at the cavity length detuning of +50 µm.
The role of divertor pumping in plasma detachment and particle exhaust in a closed divertor
Authors: Sang Chaofeng , Stangeby P.C. , Guo H.Y. , Wang Dezhen
Published: October 2020

The impact of pumping on divertor power dissipation and particle exhaust in a closed divertor with flat target configuration is examined using SOLPS modeling. A closed divertor can increase neutral pressure and enhance radiative dissipation; accordingly it has been proposed as a direction for the design of advanced divertors to achieve detachment at as low an upstream plasma density as possible. However, the necessity to pump the closed divertor results in a reduction of the high density and pressure of neutrals near the target. The quantitative effect of this reduction on the achievement of detachment is assessed here. By independently varying both the pumping speed S using different pump opening surface areas, together with the upstream plasma density at the outside midplane,

n

e
,
s
e
p

OMP

, it is established quantitatively how the pump exhaust rate, Q
exh (particles/s), depends on these two quantities. As expected, pumping increases the detachment onset density,

n

e
,
s
e
p

O
M
P
,
o
n
s
e
t

; however, for S = 40 m3 s−1, it is shown that Q
exh = 1 kA and detachment onset—as defined by a peak T
e at the outer target of ∼5 eV—can be obtained simultaneously, which is consistent with DIII-D requirements for particle and energy exhaust. By placing the pump surface at different distances from the target, it is established how the pump location affects Q
exh, which in turn affects the divertor plasma conditions, including achievement of detachment. High pumping speed reduces neutral density and radiated power, thus increasing T
e and the heat flux to the target. The essential difference between the various pump locations is the ratio of Q
exh to the total number of neutral deuterium particles plus carbon particles (atoms and ions) in the outer divertor, f
exh = Q
exh/N
tot-OD. It was found that the best pump location is near the target at the CFR (common flux region) side of the closed divertor slot. Pumping at the PFR (private flux region) side near the target gave similar results, indicating flexibility with regard to pump location in closed divertors with a flat target plate.
Overview on the Preparation and Heat Transfer Enhancement of Nanofluids
Authors: Ji Junyu , Lu Wei , Si Cong , Zhang Shufeng , Yao Xiangyang , Wang Weihua , Chu Delin
Published: October 2020

Due to the great advantages of high thermal conductivity and strong heat exchange capacity, nanofluids have attracted great intrest in many heat exchange fields, such as thermal power plant, solar energy, automobile cooling, nuclear power facilities and so on. In this paper, it reviews the research progress of nanofluids including preparation process, suspension stability, thermal conductivity, viscosity,and gives emphasis to analyse the influence factor of nanofluid convective heat transfer.
Study on the Influence of Polycarboxylate Superplasticizer Compound on the pump PHC
Authors: Fang Yunhui , Ke Yuliang , Zhang Xiaofang , Zhu Shaohong , Qiu Yuetao , Chen Xiaobin , Lin Tianxing , Guo Yuanqiang , Ma Xiuxing
Published: October 2020

This aricle disclosed the effects of polycarboxylate superplasticizer (PCE), air entraining agent, defoamer, accelerator on the properties of prestressed high-strength concrete (PHC). The introduction of DAC and AMPS into the molecular structure of PCE is helpful to improve compressive strength of PHC. The air entraining agent can be used to improve the PHC workability. The Defoamers and accelerators are beneficial for increasing PHC compressive strength. The admixture compounding technology by using PCEs, air entraining agents, defoamers and accelerators can help to get excellent properties of PHC.
Experimental Study on the Flexural Strength of Marble Industrial Powder Concrete
Authors: Li Guishan , Zhang Jintuan , Cai Desuo , Wang Tongkuai , Zhang Fan , Meng Donglin , Hu Qin , Zhang Huaiyang
Published: October 2020

The flexural strength and cube compressive strength of marble industrial powder concrete were studied by orthogonal test method. 25 orthogonal test groups and 1 contrast test group with the mineral admixture content 0% were designed to carry out the flexural and compressive tests. The strength of concrete with different substitution rate and fineness is obtained, and the mechanism of influence on each strength is analyzed. The experimental results show that the concrete flexural strength is reduced by the addition of marble powder, but it can meet the requirement of engineering application when the substitution rate is less than 10%. According to the orthogonal test, the main factor affecting the flexural strength of marble industrial powder concrete is the substitution rate of marble powder, and the secondary factor is the fineness of marble powder. The effect of marble powder on the flexural strength and compressive strength of concrete is basically the same. The ratio of flexural strength to cubic compressive strength of marble powder concrete with different substitution rate and fineness is 0.16.
Molecular Structure Influence of Polycarboxylate Superplasticizer on the pump PHC
Authors: Fang Yunhui , Zhang Xiaofang , Ke Yuliang , Lai Huazhen , Zhong Lina , Li Geli , Lin Yanmei , Lin Tianxing , Guo Yuanqiang , Ma Xiuxing
Published: October 2020

This article disclosed to design a series of polycarboxylate superplasiticizer (PHC) by free radical polymerization. The PEO grafting side chain desity and main chain compositon of PCE greatly influenced the concrete performance. The PEO long side chain of PCE can produces steric hindrance effect in concrete to provide the flowability. The functional monomer DAC and AMPS incorporated into the main chain can improve the compressive strength. The suitable water dosage in the PHC mix proportion is 145 kg/m3 and 150 kg/m3.
Multi-scale Modelling and Wind-induced Vibration Analysis of Transmission Tower Structure
Authors: He Huan , Li Zhengying , Zhang Ke
Published: October 2020

Based on the theory of node displacement compatibility, the multi-point constraint equations of beam-solid elements are derived. The beam element model and multi-scale model are established to analyze the wind-induced vibration response of the transmission tower. The analysis results demonstrate that the dynamic response of the two models is similar in the elastic stage, but the response of the multi-scale model is larger than that of the beam element model in the plastic stage. The main reason is that the multi-scale model can consider the stiffness degradation and cracking of the angle cleat, which will in turn influence the mechanical performance and failure mode of the structure.
Application and Progress of Microstructure and Mechanical properties Control Methods for Ultra-High Strength Steel in Rolling Process
Authors: Chen Yongli , Zhou Xuejiao , Li Yuhua
Published: October 2020

This paper introduces traditional ultra-high steels and the dilemma of its processing, the application of the rolling method in the production of ultra-high strength steel, Nano-fine grain preparation techniques for improvement of strength and toughness, Phase composition regulation to improve mechanical properties. Summed up microstructure and mechanical properties control methods for ultra-high strength steel in the rolling process, Using the methods innovatively solves the flexible rolling process produces 1600 MPa grade ultra-high strength and toughness nano-scale B/M complex phase under the existing equipment conditions of ordinary steel enterprises.
Preparation and Properties of High-Conductive Graphene Nanosheets Reinforced Epoxy Composites
Authors: Zhang Haiyun , Wang Danyong , Liu Juncong , Wei Huazhen , Zhang Jianqin , Liu Fangbiao , Xu Jingli , Liu Aiyun , Wang Ronghui , Jia Huamin , Guo Jianfen , Li Fuqiang , Li Shuhu , Qin Zhenming , Liu Yadong
Published: October 2020

Due to the growing needs of thermal management in modern electronics, epoxy-based composites are increasingly demanded in heat dissipating materials. A simple preparation of composites with high thermalconductivity was developed through the graphenenanosheetshomogeneously dispersed in theepoxy matrix. A high thermal conductivityof 0.4843W/mK ( increased by184% over that of pure epoxy) could be obtained for the compositeswith a filler content of 5wt.%. It was proved that high aspect ratio of GNPs are critical issues of theconstitution of a special interface region between the GNPs and epoxy matrix of the composites.The more than mere additive effect on the through-thickness thermal conductivity suggests synergistic physical interactions between graphenenano sheets leading to further enhancement in the through-thickness thermal conductivity. Thus, the graphene-reinforced composites are promising for usageas an efficient heat spreader for heat dissipation applications.
Performance Analysis of Polypropylene Filament Geotextile Heat-Resisting Asphalt Mixture
Authors: Liu Ying , Du Tianling , Chen Lei
Published: October 2020

To illustrate the damage effect of polypropylene filament geotextile against the thermal shock of hot asphalt mixture, the simulation analysis is carried out with ABAQUS finite element software, and the single filament structure of polypropylene filament geotextiles was observed by electron microscopy from the point of view of physical structure, a conclusion is drawn like this: Thermal shock of hot asphalt mixture higher than melting point of polypropylene filament geotextiles will not damage polypropylene filament geotextiles during paving process, its monofilament structure, with a smooth surface and a tight organization, is one of the reasons for resistance to the impact of hot asphalt mixture.
The Hybrids of Graphene with the Polymer of Porphyrin: Synthesis, Characterization and Their Nonlinear Optical Properties
Authors: Liang Chen , Duan Qian
Published: October 2020

A series of comb-shaped porphyrin polymers were synthesized by RAFT polymerization which modified the graphene via π-π bond to synthesize the polymer composite and made the graphene could better disperse in organic solvents. The reverse saturable absorption (RSA) of the hybrid materials were studied. The π-π bonding between poly-porphyrin (PPor) and graphene was confirmed by UV-Vis and fluorescence spectra. The strong fluorescence quenching in composites suggested the energy transfer between the PPor and graphene. The RSA properties were studied by open aperture Z-scan technique at 532 nm in nanosecond regime. At same transmission intensity, the hybrids showed a better NLO property which compared to the PPor and graphene.
Mechanical Property Evolution Model of Polyimide Film by Far Ultraviolet Irradiation
Authors: Shen Zicai , Xia Yan , Zhao Chunqing , Ding Yigang , Fan Peng , Li Jian
Published: October 2020

The deuterium lamp was used as simulation source to study the Mechanical property of polyimide film in space far ultraviolet environment, thermo gravimetric and XPS was used to analyze the evolution mechanism of polyimide film in different exposures. It was found that the mechanical properties such as tensile strength and rupture elongation of polyimide film decrease firstly and then exponent increase until to stable. From XPS analysis, it can be found that there were rupture and crosslink of chemical bond in polyimide film. In early stage of far ultraviolet radiation, the rupture of C-N, C=O, C-O, C-C bond is for the decrease of mechanical properties of polyimide film, and as the increase of far ultraviolet exposure, the release of N, and formation of C-N bond is for the increase of mechanical properties of polyimide film.
Preparation and Lithium Storage Properties of LiV3O8 as a Cathode Materials
Authors: Li Lin , Liu Qing , Cheng Jinsong , Zhao Rongfei
Published: October 2020

The LiV3O8 cathode materials was successfully synthesized by PEG-assisted freeze drying combination with calcination treatment process. The annealing temperature affected the electrochemical properties of the LiV3O8 cathode materials. The LiV3O8 cathode materials annealed at different temperatures were characterized by X-ray diffraction, Scanning electron microscopy, and Galvanization charge/discharge profile measurement. The results demonstrated that with the increase of sintering temperature, accompanied with the change of the morphology of the nanoparticles to nanorods. The LiV3O8 fabricated at 500 °C (LVO500) showed the high capacity and good rate capability (after 100th, a reversible discharge capacity up to 218 mAh g−1).
Effects of Geometric Parameters and Axial Tension on Vibration Characteristics
Authors: Wang Bohan , Cheng Li , Ding Junliang , Bao Xuechun , Wang Changkai , Li Dongchun
Published: October 2020

The vibration frequency of the aero-engine blade is affected by its own mass characteristics and steady-state centrifugal force, which can be used to adjust the blade resonance frequency to avoid the exciting source and prolong the fatigue life of the blade, and can also be used to approach the exciting source frequency and guide the design of ultrasonic fatigue specimens. Through the combination of mechanical analysis and finite element simulation, the influence mechanism of geometric parameters and axial tension on modal frequency is analyzed from the point of view of vibration and energy, the influence law is obtained, and the optimal design of two kinds of three-point bending specimens is completed. The resonant frequency error calculated by finite element method is controlled within ±5Hz, and the frequency is 20.03 kHz verified by ultrasonic fatigue test, which meets the accuracy requirements, which provides a reliable theoretical support for the design of simulated blade ultrasonic fatigue specimens.
Thermal Stability and Mechanical Property of Vinyl-Functionalized Polyborosiloxane and Silicone Rubber
Authors: Zhang Yulong , Zang Chongguang , Jiao Qingjie
Published: October 2020

In this study, under solvent-free condition, the vinyl-functionalized polyborosiloxane (BSiOVi) was synthesized by reacting triethoxyvinylsilane (VTEOS) and boric acid (BA) and the chemical structures were characterized by GPC and FT-IR. The results indicated that the BSiOVi containg Si-O-B bonds and vinyl groups was successfully synthesized. Moreover, the thermal stability and compressive strength after heat treatment were studied. TG-DTG result indicated that the BSiOVi with more Si-O-B high energy bonds possessed the better thermal stability than that of silicone rubber only possessing Si-O-Si bonds. The results of mechanical property of BSiOVi showed that the BSiOVi after heat treatment possessed the higher compressive strength than that of silicone rubber. This is because that the polymerization of Si-CH=CH2 groups could improve the crosslinking density, and the ceramic transformation of BSiOVi after heat treatment tend to the formation of dense SiBOC nanocomposites. We believed that the BSiOVi could be effectively served high temperature resistant matrix resin for ceramic matrix.
Research on Magnetism and Magnetization Intensity of Magnetic Fluid
Authors: Hao Ruican , Liu Huagang , Feng Zhixin
Published: October 2020

Magnetic fluid is a liquid magnetic material with high magnetization, fluidity and superparamagnetism. The composition and the performance of magnetic fluid in magnetic field were introduced. Magnetic model of magnetic fluid for application was established. Magnetic particles could be seen as magnetic needles with certain N-S directions whose direction could be controlled by external magnetic field. Magnetization mechanism of magnetic fluid was researched. Measurement principle of magnetization intensity was studied and the formulas were deduced. The working principle of vibrating sample magnetometer was introduced and the magnetization curve of magnetic fluid was measured and plotted. It was concluded that magnetic fluid has superparamagnetism which means that the remanence and coercivity of aggregation of magnetic fluid are both zero. Magnetism is an important characteristic of magnetic fluid for engineering applications that magnetic fluid with high magnetization intensity will be explored and researched.
Nitrogen-doped CuAlO2 Films Prepared by Chemical Solution Deposition
Authors: Liu Weiwei
Published: October 2020

N-doped CuAlO2 thin films were prepared by chemical solution deposition and annealed at different temperature in nitrogen ambience. Single phase N-doped CuAlO2 thin films can be obtained by annealing the films at 1000 °C. Crystallization quality of the film was improved by increasing annealing temperature. XPS measurements showed the N has successfully incorporated into the CuAlO2 thin films. Above results show that the chemical solution deposition was an effective way to prepare the N-doped CuAlO2 thin films which can be used in optoelectronic devices.
The Simulation of Resonant Mode and Effective Electromechanical Coupling Coefficient of Lithium Niobate Crystal with Different Orientations
Authors: Bai Xiaoyuan , Shuai Yao , Luo Wenbo , Wu Chuangui , Zhang Wanli
Published: October 2020

At present, the proportion and role of thin film bulk acoustic wave (FBAR) filters in mobile communication products are becoming more and more obvious due to its higher work frequency and smaller size. As a commonly used piezoelectric material, aluminum nitride (AlN) limits the bandwidth of the FBAR filter because of its small electromechanical coupling coefficient (kt
2) of ~6.5%. On contrast, lithium niobate (LiNbO3, LN) crystals with some certain specific orientations have much better acoustic properties, making this type of material the promising candidate for FBAR applications. In this work, the acoustic resonant mode in LN crystal is analyzed by FEM simulations. In order to obtain the optimal orientations with good longitudinal wave property, Euler angle (EA) method is used to simulate the resonant modes and calculate the corresponding kt
2 of different orientations. Besides, the correctness of EA method has been demonstrated in this work by comparing the displacement change under electrostatic field with the traditional matrix transformation operation depending on the piezoelectric effect. The simulations show that the 43°Y-cut LiNbO3 has a high kt
2 and a pure longitudinal wave vibration mode simultaneously, making this orientation the most proper candidate for FBAR filters application with large bandwidth.
Direct Lightning Flash Protection of Satellite Antenna
Authors: Feng Jun , Zhang Qian , Guo Yanshen , Wu Jianlong , Chen Meiyi
Published: October 2020

It will cause some problems like improper way of lightning protection and improper height of lightning rod in the design for direct lightning flash protection of satellite antenna, which may increase the probability of lightning strike, due to the lack of express provisions in relevant standards about satellite antenna lightning protection level and direct lightning flash protection ways. A way was presented for the determination of lightning protection level based on probability and risk assessment of lighting through a specific instance, by comparing the probability of lightning, costs and difficulties for construction between two different types of lightning protection ways under the same conditions for indirect lightning protection, an appropriate way was proposed for direct lightning flash protection by using lightning rod installed on the satellite antenna.
Application and Prospects of Prefabricated Buildings in Rural Areas of China
Authors: Ru Qiujin , Feng Jiandong , Lu Qin
Published: October 2020

This article analyzes the status and existing problems of rural housing in China. In order to promote the construction of new countryside and improve the quality of rural housing, prefabricated buildings should be preferentially adopted in rural areas. According to the application and promotion status of prefabricated buildings, compared with traditional buildings, the advantages of prefabricated buildings are obvious. However, there are many obstacles in the promotion of prefabricated buildings in rural areas. In order to change the appearance of buildings in rural areas, more policy support should be provided during the construction of new farmers, so that prefabricated buildings can be better promoted.
Fe3O4/Graphene Aerogel as High-Performance Flexible Anode for Sodium-Ion Battery
Authors: Wei Guangling , Zhou Jiahui , Xie Man
Published: October 2020

To overcome the volume expansion and poor electrical conductivity of metal oxides, graphene aerogel encapsulated Fe3O4 nanoparticles composite material was synthesized by hydrothermal self-assembled method. Fe3O4 was synthesized in situ during the self-assembled process, effectively relieving volume expansion and pulverization of metal oxides by the encapsulation of graphene aerogels (termed Fe3O4@rGA). Besides, the graphene aerogel enhances the conductivity of the composite material. The Fe3O4@rGA used as anode material for sodium ion batteries in this study displayed an excellent initial capacity of 220 mA h g−1 at 100 mA g−1, and even showed reversible capacity of 82 mA h g−1 at 10 A g−1.
Research on the Development Status, Strategic Choice and Business Model of China’s Charging Pile Industry
Authors: Tan Qingkun , Wu Peng , Wei Tang , Yu Zhang
Published: October 2020

The interaction between electric vehicles and power grids can achieve the functions of cutting peaks and valleys of load, participate in frequency modulation, and provide reserve service. It is of great significance for the safe and economic operation of power grids and the ability to improve the capacity of new energy power generation. However, due to the lag of the development of China’s charging pile industry, which constrained the development of electric vehicles. This paper analyzes the key issues of market mechanism and infrastructure of charging piles. First, this paper summarizes the development status of China’s charging pile and proposes the research route for the development of charging pile bottlenecks; secondly we analyze China’s policies on different stages and construct implementation path of charging pile. By comparing the basic indicators, related policies and related innovation activities of the charging pile for China, we conclude that the development of the national electric vehicle industry needs to be increased in terms of government policies, business model innovation and public awareness.
Research Progress of Soil and Water Conservation in Pisha Stone Area of Yellow River
Authors: Shen Zhenzhou , Yao Wenyi , Xiao Peiqing , Wu Yan , Song Jingru , Liu Jie , Liu Mingxin , Yang Jishan , Yang Haoyu , Duan Huiling , Li Li , Dong Feifei , Li Weiwei , Liu Cuixia , Bi Wenyan , Geng Xiaodong
Published: October 2020

Ecological degradation and serious soil erosion in the sandstone area of the Yellow River Basin have resulted in a large number of manpower and material resources during the decades-long governance process, and various governance measures have been developed. This article introduces the erosive sandstone area and the existing erosive sandstone erosion control technology, analyzes the methods, materials, and treatment effects of the slope top-slope surface-ditch, and then focuses on the ecology of the Ordos Plateau volcanic sandstone area undertaken by the Yellow River Hydraulic Research Institute. Comprehensively consider the governance technology project, and on the basis of this project, it is envisaged to introduce the concept of buffer zone, in order to provide more research ideas for sandstone governance.
Monthly Streamflow Prediction Based on Random Forest Algorithm and Phase Space Reconstruction Theory
Authors: Peng Feng , Wen Jie , Zhang Yao , Jin Junying
Published: October 2020

In order to find an effective time series forecasting method, a random forest prediction model based on phase space reconstruction theory is proposed in this paper. The Cao method and mutual information function method are used to reconstruct the phase space, and the parameters of the random forest (RF) model are discussed. The feasibility of the model is verified by analyzing the monthly runoff data of Pingshan hydrological station in Jinsha River Basin. Compared with BP neural network (BPnet) model and traditional support vector machine (SVM) model which optimizes parameters by grid algorithm, random forest model has higher prediction accuracy and less calculation in dealing with complex nonlinear hydrological time series as shown by the result.
Precipitation and Growth of Ni-Rich Substances in the Oxide Scale of Steel in Mixed C2h5oh-H2o Atmosphere
Authors: Zheng Chengming , Zhao Yan , Tian Qingchao
Published: October 2020

Nickel is an iconic alloying element in the piercing plug steel. In order to study the formation mechanism of Ni-rich substances in oxide scale of steel under mixed C2H5OH-H2O atmosphere, the high-temperature oxidation experiment was carried out by employing steels with varied Cr and Ni contents, and the oxidation characteristic was explored by using scanning electron spectroscope (SEM), energy dispersive X-ray spectroscopy (EDS), metallographic microscope (OM) and Image-Pro Plus. Under the experimental conditions, it is found that Ni promotes the formation of denser inner oxide scale while Cr inhibits inner oxidation effectively. Congregation of Ni-rich substances is a diffusion process strongly relying on the Ni content of the steel. The total Ni-rich substances dependence of Ni content follows the parabolic law. It is proposed that the Ni-rich substances precipitate once the oxidation of Fe or Cr atoms leaves vacancies for the nearby Ni atoms to fill in to form a substitute Ni-rich crystal structure, and then the Ni-rich substances congregate and grow up as oxidation proceeds. The results are meaningful for the reasonable design of piercing plug steel.
Present Situation and Key Technology Analysis of Bimetallic Composite Roll Preparation Method
Authors: Shi Xiaofang , Zhu Chunli , Zhu Zhenghai , Chang Lizhong
Published: October 2020

Bimetallic composite roll has a great influence on improving roll quality and reducing roll preparing cost. In this paper, the development status of bimetallic composite roll preparation technology is analysed, and the advantages and disadvantages of various manufacturing methods of composite roll are discussed. Based on the preparation process of bimetallic composite roll, the key technologies affecting the quality of composite roll are analyzed, and a new idea of preparing high-performance composite roll based on "width adjusting mold coupling multi-electrode rotating technology" is proposed.
Study on Austenite Grain Growth Behaviour of New Pipeline Steel for Deep Sea
Authors: Zhao Xin , Bai Hongyang
Published: October 2020

The austenite grain growth behaviour of new pipeline steel for deep sea was researched by using optical microscope. The results show that the microstructures are homogeneous and the grain size increases slowly while the soaking temperature increases from 1120°C to 1180°C. However, the abnormal growth phenomenon can be observed in the specimens reheated at 1210°C. The austenite grain growth behaviour can be described by following equations: lnD = 7.7738- 6242/T (1120°C< T< 1180°C) and lnD = 51.2948-69510/T (1180°C<T <1210°C).
Study on Pickering Emulsions Stabilized by Tea Polyphenols/Gelatin/Chitosan Nanoparticles
Authors: Wang Hui , Bai Yan , Shao Dongxu
Published: October 2020

The tea polyphenols/gelatin/chitosan (TGC) nanoparticle was prepared and applied to stabilize Pickering emulsions. The particle size of TGC nanoparticle was about 880 nm with the mass ratio of tea polyphenols to gelatin 1:2. The apparent viscosity of TGC nanoparticle showed typical non Newtonian pseudoplastic behavior, and increased with the increase of tea polyphenols content at the same shear rate. The size distribution of Pickering emulsions stabilized by TGC nanoparticles was highly uniform. The average droplet size of emulsions increased from 46 μm to 80 μm when the mass fraction of oil phase increased from 30% to 60%. The emulsified volume fraction increased with the increase of oil fraction. Nanoparticles provide a strong force on the oil-water interface and effectively inhibit the aggregation and coalescence of droplets. The Pickering emulsion exhibited good storage stability and good stability under high temperature heating.
Lumped RC Thermal Network Method Applied to Transient Temperature Calculation of High Voltage Bushing and Its Insulation Life Assessment
Authors: Zhang Shiling
Published: October 2020

To analyze how the internal transient temperature of the high voltage condenser bushing varies with its short-time current carrying capacity and long-aging properties, lumped RC thermal network model applicable to the structure of HV bushing is proposed. This model considers three heat transfer modes of the conduction, the convection and the radiation, and the changing relationship between material properties and temperature and the the thermal RC network topology is realized based on the MATLAB/SIMULINK. In the example of 550kV oil-SF6 bushing, the calculation results of transient temperature thermal network are in good agreement with the actual temperature rise test results which proves effectiveness and practicality of lumped RC thermal network. We used the thermal network to confirm the periodic transient variation at the hottest spot of HV bushing and analyze the shot-time current carrying capacity by step load curve fitting circadian cycle change load. Finite element method and thermal network method are used to get the electric and thermal stress respectively and HV bushing long-aging properties analysis was conducted based on classic ZHURKOV and CRINE electric and thermal combined aging model. This paper applies lumped RC thermal network method to transient temperature calculation and internal insulation life assessment of the HV bushing, reinforced classic bushing design method only considering rated steady-state operating conditions and has theoretical guidance on assessing short-time current-carrying capacity and long-aging properties in high voltage bushings.
Research of Installation Stress of EMU Aluminum Alloy Beam and its Connecting Structure
Authors: Fan Ruirui , Zou Hua , Sun Shouguang , Zhang Yonggui
Published: October 2020

Bolt hanging is one of the common ways of rail vehicle hanging equipment. In this paper, the assembly structure of a type of EMU and converter is taken as the research object, and the load values at the four suspension points are calculated by theoretical calculations. A simulation model of a single hanger is established, and the simulation is determined by reference to the theoretical calculation under working conditions, the stress distribution at the hanging points under different loads was studied. The results show that under different loading conditions, the stress distribution of beam is basically the same. The maximum stress of the beam occurs at the point where it contacts the bolt head. Compared with other regions, the stress at the corner of the T-slot of the beam is also larger.
Indoor Scene Semantic Segmentation Based on RGB-D Image and Convolution Neural Network
Authors: Wang Guitang , Wang Ziyu , Chen Yongbin , Wang Guozhen , Chen Jianqiang
Published: October 2020

In recent years, convolutional neural network has been widely used in image semantic segmentation and achieved great success. In this paper, a semantic segmentation network of indoor scene based on rgb-d image is proposed: SRNET (Strong supervision Residual Net). In this network model, the original data is processed by separate training and gradual fusion, and the mandatory supervision module is added in the decoding stage, which effectively improves the accuracy of semantic segmentation. At the same time, anti residual decoding method and jump structure are introduced to reduce information loss. Experimental results show that the segmentation accuracy of this model is better than most of the current segmentation algorithms.
Effect of Laser Shock Strengthening on Modal Frequency
Authors: Liu Jingyuan , Cheng Li , Li Dongchun , Wang Bohan , Ding Junliang , Zeng Lin
Published: October 2020

The phenomenon of laser shock strengthening (LSP) changing the resonance frequency of a structure can be used to adjust the frequency of aero-engine blades, and has a broad application prospect. In this paper, through the combination of mechanical analysis, numerical simulation and vibration test, the effect of LSP technology on structural vibration characteristics is studied. The influence mechanism of local stiffness changes on the modal frequency of the structure is analyzed from the perspective of vibration and energy. It is found that when the laser shock is strengthened in a region with large bending deformation, the greater the contribution to the overall modal stiffness and elastic potential energy, the greater the modal frequency. The impact is also greater. Established a mapping relationship among laser shock strengthening, local stiffness and modal frequency, and finally proved that LSP technology can significantly change the local elastic modulus of TC4 titanium alloy, which provides a reliable application of the technology in the production department Theoretical support.
Study of the k-ary GCD Algorithm
Authors: Amer Ismail F , Saad Muhammad
Published: October 2020

In our paper, we consider some approaches to accelerating the calculation of the Greatest Common Divisor (GCD) of natural numbers for given A and B based on the k-ary GCD algorithm. Such a task arises in the implementation of many mathematical and number-theoretic algorithms, for example, in cryptography and number theory (see [8]).
On the linear complexity of new generalized cyclotomic binary sequences of period p

n

q

m
Authors: Edemskiy V A , Garbar S V
Published: October 2020

Sequences with high linear complexity are of importance in different applications. These sequences can be derived from generalized cyclotomic classes. In this paper, we construct new families of binary sequences of period p

n

q

m
using new generalized cyclotomic classes, as well as study the linear complexity of these sequences. We obtain the estimate of the linear complexity of new sequences and show that they have high linear complexity for m + n > 2.
Comparative investigation of electrophysical characteristics of ceramic and single crystal LiNbO3
Authors: Efremov V V , Shcherbina O B , Palatnikov M N , Masloboeva S M
Published: October 2020

Electrophysical characteristics have been studied in ceramic and single crystal LiNbO3 of congruent and near-congruent composition. The comparative study has been carried out in a wide temperature range (290-800 K). Dispersion of the real part of the dielectric constant ε′ has been considered. Temperature dependences ε′(T) and σ(T) have been obtained and value of static conductivity has been determined in ceramic and single crystal LiNbO3 in the given temperature range. Temperature dependences of specific static conductivity σ

dc
have been obtained due to impedance spectroscopy data analysis. Ceramic LN conductivity has been shown to be much higher in the whole studied temperature range. Charge carriers activation enthalpy in high-temperature area (above 420 K) is H

a
= 0.88 eV for ceramic LN and H

a
= 1.24 eV for single crystal LN.
Analytical inversion of one-dimensional operators of diffraction of electromagnetic waves in Sobolev spaces
Authors: Eminov S I
Published: October 2020

The paper develops a method for analytical inversion in Sobolev spaces on a segment of one-dimensional integral diffraction operators that depend on a parameter. The method is based on positive definiteness of operators and the presence of an orthonormal basis. For a special case, the operator of diffraction of an H – polarized wave on a band or on the surface of a vibratory antenna, the inverse operator is explicitly constructed. It is possible to study the physical properties of surface currents using the inverse operator, as well as to construct an effective numerical method for solving integral diffraction equations.
On refractive index of optical radiation of polycrystalline silicon films
Authors: Gavrushko V V , Ionov A S , Lastkin V A , Telina I S
Published: October 2020

Transmission spectra of layers of polycrystalline silicon on sapphire with a thickness of 0.1 … 0.8 µm were investigated. The refractive indices were determined in the range of 0.5 … 2.7 μm. An increase in the refractive index with decreasing wavelength was established. An increase in the film thickness from 0.1 to 0.8 μm led to a decrease in the refractive index from 3.2 to 2.8 at λ = 1.5 μm. Compared to single crystals, the refractive indices of polycrystalline films were lower. The data obtained can be used to build models for calculating the optical characteristics of complex compositions.