bluuebunny/crossref_metadata_2025 huggingface dataset:
Saturation of electron emission with increasing ultrarelativistic intensity of the Gaussian laser pulse
Authors: Borovskiy A V , Galkin A L
Published: May 2021

Symmetric electron trajectories in the field of a Gaussian laser pulse are calculated as trajectories with compensation of the dynamic shock at the initial instant of motion. It is shown that the symmetric trajectories have an extremal property, namely, at a fixed peak intensity of the pulse, the time dependence of the electron emission intensity from a symmetric trajectory has the maximum width and amplitude compared to all other trajectories. Formation of paired peaks of electron emission intensity with changing laser pulse peak intensity is analyzed. It is found that the electron emission energy saturates with increasing peak intensity of the laser field in the ultrarelativistic region.
Input–output slope curve estimation in neural stimulation based on optimal sampling principles
*
Authors: Mohammad Mahdi Alavi Seyed , Goetz Stefan M , Saif Mehrdad
Published: May 2021

This paper discusses some of the practical limitations and issues, which exist for the input–output (IO) slope curve estimation (SCE) in neural, brain and spinal, stimulation techniques. The drawbacks of the SCE techniques by using existing uniform sampling and Fisher-information-based optimal IO curve estimation (FO-IOCE) methods are elaborated. A novel IO SCE technique is proposed with a modified sampling strategy and stopping rule which improve the SCE performance compared to these methods. The effectiveness of the proposed IO SCE is tested on 1000 simulation runs in transcranial magnetic stimulation (TMS), with a realistic model of motor evoked potentials. The results show that the proposed IO SCE method successfully satisfies the stopping rule, before reaching the maximum number of TMS pulses in 79.5% of runs, while the estimation based on the uniform sampling technique never converges and satisfies the stopping rule. At the time of successful termination, the proposed IO SCE method decreases the 95th percentile (mean value in the parentheses) of the absolute relative estimation errors (AREs) of the slope curve parameters up to 7.45% (2.2%), with only 18 additional pulses on average compared to that of the FO-IOCE technique. It also decreases the 95th percentile (mean value in the parentheses) of the AREs of the IO slope curve parameters up to 59.33% (16.71%), compared to that of the uniform sampling method. The proposed IO SCE also identifies the peak slope with higher accuracy, with the 95th percentile (mean value in the parentheses) of AREs reduced by up to 9.96% (2.01%) compared to that of the FO-IOCE method, and by up to 46.29% (13.13%) compared to that of the uniform sampling method.
Development and performance of high voltage electrodes for the LZ experiment
Authors: Stifter Kelly
Published: May 2021

LZ is a next-generation dark matter search experiment designed to significantly extend our sensitivity to WIMP dark matter candidates. At the core of the LZ detector is a dual-phase xenon time projection chamber (TPC) with a 7-ton active mass. To observe signals from low-energy nuclear recoils, including WIMP-xenon scatters, four custom-woven wire-mesh grids of 1.5m diameter establish strong electric fields in the TPC to drift ionization electrons across the volume and extract them from the liquid surface. As a result of the high electric fields, dielectric breakdown between high voltage surfaces and spurious electron emission from regions of high surface fields are major concerns. To mitigate these risks, an R&D program exploring design geometry in high field regions, cleanliness procedures, and surface treatments has been carried out using a comprehensive suite of three mid-scale dual- and single-phase xenon detectors. These proceedings will summarize the design and construction of the LZ grids, and several aspects of the high voltage performance seen in the testing program.
Dark Matter Searches with the COSINE-100 Experiment
Authors: Govinda Adhikari
Published: May 2021

COSINE-100 is a direct dark matter detection experiment that aims to test DAMA/LIBRA’s claim of dark matter discovery using 106 kg of low-background NaI(Tl) detectors submerged in a 2-tonne liquid scintillator veto. The physics run of the experiment began in September 2016, and a 3.5 count/kg/day/keV background level within the 2-6 keV region of interest has been achieved. Several physics analyses, including WIMP searches and an annual modulation search, have been performed using a 2 keV energy threshold. Recently, this threshold has been lowered to 1 keV. In this talk, we describe the method used to lower the threshold to 1 keV and recent results with this lowered threshold.
DARWIN: direct dark matter search with the ultimate detector
Authors: Macolino Carla
Published: May 2021

DARk matter WImp search with liquid xenoN (DARWIN) is a future experiment for the direct detection of dark matter based on a multi-ton liquid xenon time projection chamber. The main goal of DARWIN is to reach an unprecedented sensitivity to WIMP (Weakly Interacting Massive Particle)-nuclear recoil cross sections for a large WIMP mass range, down to the level where the irreducible background from neutrino interactions with the target is dominant. This ultra-low background experiment will also have competitive sensitivity to test other dark matter hypotheses such as dark photons and superWIMPs and to detect other rare events like solar neutrinos, neutrinoless double-beta decay of 136Xe, solar axions and neutrinos from galactic supernovae. In this paper we present the design of the DARWIN detector and the estimated WIMP sensitivity based on the expected backgrounds. Other rare event searches are also discussed.
The readout system based on the ultra-fast waveform sampler DRS4 for the Large-Sized Telescope of the Cherenkov Telescope Array
Authors: Nozaki S , Blanch O , Delgado C , Gliwny P , Hadasch D , Inome Y , Katagiri H , Kubo H , Kobayashi Y , Mazin D , Moralejo A , Nogami Y , Paoletti R , Saito T , Sakurai S , Sitarek J , Takahashi M , Teshima M , Yamamoto T
Published: May 2021

The Cherenkov Telescope Array (CTA) is the next-generation ground-based very-high-energy gamma-ray observatory. By using three types of telescopes CTA can cover a wide energy range (20 GeV–300 TeV) with an order of magnitude higher sensitivity than the current telescopes. The Large-Sized Telescope (LST) is designed to detect 20 GeV–1 TeV gamma rays thanks to the large light collection area, sensitive photosensors, a fast trigger system, and readout electronics. The camera readout system must have a high signal-to-noise ratio and a linear signal sampling with a large dynamic range in order to efficiently detect dim and low-energy atmospheric showers. To meet this requirement we use the Domino Ring Sampler version 4 (DRS4), which also enables ultra-fast sampling with low power consumption. Some of the intrinsic characteristics of DRS4 chips require software corrections. These procedures lower the effect of non-Gaussian noise contribution and improve the timing resolution of the system. In this contribution we discuss the calibration algorithms and the resulting performance.
Signal Readout Electronics for LEGEND-200
Authors: Willers Michael
Published: May 2021

LEGEND (Large Enriched Germanium Experiment for Neutrinoless Double-Beta Decay) is a ton-scale experimental program to search for neutrinoless double beta (0vββ) decay using high-purity germanium detectors enriched in the isotope 76Ge. An observation of 0vββ decay would unequivocally prove the existence of lepton number violation and provide insight into the nature of neutrino masses.

On-site construction for the first 200-kg phase (LEGEND-200) of the experiment will start at the Gran Sasso underground laboratory (Laboratory Nazionali del Gran Sasso, Italy) in mid-2020. In order to achieve a sensitivity of 1027 years on the 0vββ half-life, ultra-clean low-noise signal readout electronics are essential as they impact both the background budget of the experiment and the efficiency of background rejection. In this contribution, the current status of the signal readout electronics for LEGEND-200 is presented.
Performance of the low threshold Optimum Trigger on CUORE data
Authors: Branca Antonio
Published: May 2021

The Optimum Trigger (OT) is based on a threshold algorithm applied on waveforms filtered by exploiting the matched filter technique. The OT trigger thresholds improve by 60 – 90% with respect to the thresholds obtained with the standard trigger, ranging between ~ 20 and 100 keV. Low trigger thresholds open the way to Dark Matter searches and to improvements in the neutrinoless double beta decay analysis. Nevertheless, running the OT on CUORE data is demanding from the computational resources point of view. For this reason, the algorithm has been revised and adapted to cope with CUORE data. The work done to implement OT in CUORE and its performances will be discussed.
Simulation study of cosmic-ray muon backgrounds for KamLAND-Zen experiment
Authors: Ieki Sei
Published: May 2021

Neutrino is a major candidate of Majorana particle and the neutrinoless double beta (0v2β) decay is the key physics to prove it. In 2019, KamLAND-Zen experiment have started data taking to search for 0v2β decay with 745 kg of 136Xe as the source. The sensitivity is restricted by the statistics of backgrounds and the most critical ones are induced by spallation reactions of cosmic-ray muons. Physics process and statistics are studied with FLUKA which is widely used simulation tool. The most critical background is the decay of 10C, while FLUKA predicts that heavy isotopes such as 137Xe can be a potential background. We apply delayed coincidence method to quantify those backgrounds and also have been developing new tools focused on space and charge features, pulse shape discrimination and particle identification.
High-energy particle physics with IceCube
Authors: Yuan Tianlu
Published: May 2021

While the Standard Model has experienced great predictive success, the neutrino sector still holds opportunities for surprises. Numerous ongoing and planned experiments exist to probe neutrino properties at low energies. The IceCube Neutrino Observatory, comprised of over 5000 photomultiplier tubes (PMTs) situated in a cubic-kilometer of ice at the geographic South Pole, lies in a unique position to measure neutrinos at energies of a TeV and higher. In these proceedings, I discuss several exciting particle physics measurements using IceCube data and probes of physics beyond the Standard Model.
First results of KamLAND-Zen 800
Authors: Gando Yoshihito
Published: May 2021

KamLAND-Zen is a neutrinoless double beta decay (0vββ) search experiment using xenon 136 and ultra-low background environment of KamLAND (Kamioka Liquid scintillator Anti-Neutrino Detector). KamLAND-Zen collaboration has prepared the KamLAND-Zen 800 project with almost 750 kg of xenon and cleaner container for xenon loaded liquid scintillator. The container production was started in May 2017 and KamLAND-Zen 800 data acquisition was started in January 2019. In this paper, we will describe the KamLAND-Zen 800 project and report on the detector condition, data quality, the first analysis results, and the prospects.
Inner balloon production for KamLAND-Zen 800
Authors: Gando A , Gando Y , Hachiya T , Hayashida S , Hosokawa K , Ikeda H , Obara S , Ozaki H , Ueshima K , Watanabe H
Published: May 2021

KamLAND-Zen searches for neutrinoless double-beta decay with 136Xe loaded liquid scintillator (LS). The LS container, a 25-μm-thick clean nylon inner balloon is a key of the experiment since one of the main backgrounds in the ROI is 214Bi from the inner balloon. In KamLAND-Zen 400 (operated from 2011 to 2015), dust contamination of the inner balloon from the environment limited the sensitivity, although the inner balloon was fabricated at a class-1 super clean room. We improved the production method of the inner balloon for KamLAND-Zen 800 (started DAQ in January, 2019) and successfully reduced the 214Bi background level to one fifteenth as compared to the 2nd phase of KamLAND-Zen 400. The inner balloon film material and requirements, improved fabrication scheme, including establishment of clean environment and dust control, will be described.
Measurements of the reactor antineutrinos with the DANSS experiment
Authors: Alekseev Igor
Published: May 2021

The detector of the reactor antineutrino DANSS is placed on a movable platform below a 3.1 GW industrial reactor of Kalininskaya Nuclear Power Plant. The sensitive volume of the detector is a cubic meter of plastic scintillator assembled from 2500 strips with dual readout by Silicon Photo Multipliers (SiPM) and conventional PMTs (in groups of 50 strips). The detector position provides simultaneously a high neutrino flux and an overburden of about 50 m.w.e., resulting in a high counting rate of inverse beta-decay events and cosmic muons induced background as low as 1.9%. The distance between the reactor core and the detector is changed in a week cycle through three positions 10.7, 11.7 and 12.7 m. This allows systematic-free comparison of the antineutrino spectra measured at different distances by the same detector.

This article presents results of the 2.5 year of data collection with more than 2 million of neutrino events collected.
Basic studies of 3-inch PMT for multi-PMT development
Authors: Inomoto M. , Ishitsuka M. , Kuze M. , Nishimura Y. , Quilain B.
Published: May 2021

Hyper-Kamiokande is the next generation large-scale water Cherenkov detector. In Hyper-Kamiokade and Intermediate Water Cherenkov Detector for its long baseline project with J-PARC neutrino beam, use of multi-PMT, which is made by combination of 3-inch PMTs, is being considered. As part of multi-PMT development, we measured the characteristics of the 3-inch PMT including the temperature dependence of dark noise rate. The dark noise rate is important characteristic for detection of low energy events including neutron tagging. In addition, since PMT is generally susceptible to the magnetic field, we confirmed the photon detection efficiency in the condition where the magnetic field was applied.
First neutrino mass measurement with the KATRIN experiment
Authors: Schlüter Lisa , Lasserre Thierry
Published: May 2021

The KATRIN (Karlsruhe Tritium Neutrino) experiment is designed to determine the effective mass of the electron anti-neutrino with an unprecedented sensitivity of 0.2 eV/c2 (90% C.L.) in a direct and model-independent way. Tritium β-decay electrons, emitted in a high-luminosity molecular source, are analyzed with a MAC-E filter. The effective electron anti-neutrino mass squared is inferred from a fit to the integral spectrum in an energy window close the tritium endpoint. In this work, we report on the analysis of the first four-week science run of KATRIN in spring 2019. Considering statistical and systematic uncertainties, we find a central value of the effective electron anti-neutrino mass of

m
v
2

=
(
−

1.0

−
1.0

+
0.9

)

eV

2

. Following the method of Lokhov and Tkachov, we derive an upper limit of 1.1 eV at 90% C.L. on the absolute neutrino mass scale.
The study of solar neutrinos and of non-standard neutrino interactions with Borexino
Authors: Zavatarelli Sandra , Agostini M. , Altenmüller K. , Appel S. , Atroshchenko V. , Bagdasarian Z. , Basilico D. , Bellini G. , Benziger J. , Bick D. , Bonfini G. , Bravo D. , Caccianiga B. , Calaprice F. , Caminata A. , Cappelli L. , Cavalcante P. , Cavanna F. , Chepurnov A. , Choi K. , D’Angelo D. , Davini S. , Derbin A. , Di Giacinto A. , Di Marcello V. , Ding X.F. , Di Lüdovico A. , Di Noto L. , Drachnev I. , Formozov A. , Franco D. , Gabriele F. , Galbiati C. , Gschwender M. , Ghiano C. , Giammarchi M. , Goretti A. , Gromov M. , Güffanti D. , Hagner C. , Hungerford E. , Ianni Aldo , Ianni Andrea , Jany A. , Jeschke D. , Kumaran S. , Kobychev V. , Korga G. , Lachenmaier T. , Laubenstein M. , Litvinovich E. , Lombardi P. , Lomskaya I. , Ludhova L. , Lukyanchenko G. , Lukyanchenko L. , Machulin I. , Manuzio G. , Marcocci S. , Maricic J. , Martyn J. , Meroni E. , Meyer M. , Miramonti L. , Misiaszek M. , Muratova V. , Neumair B. , Nieslony M. , Oberauer L. , Orekhov V. , Ortica F. , Pallavicini M. , Papp L. , Penek O. , Pietrofaccia L. , Pilipenko N. , Pocar A. , Raikov G. , Ranalli M.T. , Ranucci G. , Razeto A. , Re A. , Redchuk M. , Romani A. , Rossi N. , Rottenanger S. , Schönert S. , Semenov D. , Skorokhvatov M. , Smirnov O. , Sotnikov A. , Suvorov Y. , Tartaglia R. , Testera G. , Thurn J. , Unzhakov E. , Vishneva A. , Vogelaar R.B. , von Feilitzsch F. , Wojcik M. , Wurm M. , Zaimidoroga O. , Zavatarelli S. , Zuber K. , Zuzel G.
Published: May 2021

The Borexino liquid scintillator neutrino observatory has a unique capability to perform high-precision solar neutrino observations thanks to its exceptional radiopurity and good energy resolution (5% at 1 MeV). A comprehensive study of the pp-chain neutrinos was presented that includes the direct measurements of 7Be, pp and pep neutrino fluxes with the highest precision ever achieved (down to 2.8% in the 7Be component), the 8B with the lowest energy threshold, the best limit on CNO neutrinos and the first Borexino limit on hep neutrinos. These results are important to validate the MSW-LMA oscillation paradigm across the full solar energy range and to exclude possible Non-Standard neutrino Interactions (NSIs). In particular the effects of neutrino-flavor-diagonal Neutral-Current (NC) interactions that modify the vee and vτe couplings while preserving their chiral and flavor structures, have been investigated. At detection, the shape of the electron-recoil spectrum is affected by changes in the vee and vτe couplings, quantified by the parameters

ε
e

L
/
R

and

ε
τ

L
/
R

. New bounds to all four parameters were obtained, quite stringent compared to the global ones. In particular, the best constraint to-date on

ε
e
L

was achieved. A comprehensive summary of all the recent results on solar neutrinos from Borexino is reported in the present paper.
KAGRA Cryogenic Suspension Control toward the Observation Run 3
Authors: Yamada Tomohiro
Published: May 2021

We have newly developed a vibration isolation system to reduce vibration via heat links, which would be one of the obstacles in the control of KAGRA gravitational wave detector. KAGRA adopts cryogenic mirrors for main optics to reduce thermal noise, which is a fundamental noise source in ground-based gravitational wave detectors in 100 Hz region, and achieves the best sensitivity in this frequency region in the world. The cryogenic mirror needs to be cooled down rapidly not to waste observation time and quietly not to disturb the mirror suspension system. For the former, radiative cooling works effectively with black coatings in high temperature region. Conductive cooling will strongly work with heat links in low temperature. However, according to our calculation, it was revealed that vibration via heat links impairs the detector sensitivity in several dozen Hz. The cryogenic suspension with heat links needs to be properly controlled up to almost same frequency region, thus, we have focused on reducing transmitting vibration with Heat Link Vibration Isolation System. In this paper, we will introduce the cryogenic suspension system, cooling system and Heat Link Vibration Isolation System in KAGRA.
Reduction of radioactive impurities from the liquid scintillator by using a Metal scavenger
Authors: Yuto KAMEI
Published: May 2021

The KamLAND2-Zen experiment is a future plan to perform the search for neutrinoless double-beta decay (0vββ) by using a large liquid-scintillator (LS) based detector, i.e., KamLAND2. The KamLAND detector will be upgraded by increasing the light yield of scintillation. One of the upgrade plans consists of using a new linear alkylbenzene (LAB) based LS. We have developed the LAB-LS radio-purification method by using a metal scavenger. The scavenging process resulted in a Pb-removal efficiency of 90.1±1.0% at most, and LS performance parametrics, such as light yield, light transparency, amount of radioactive impurities remaining, and the concentration of components were observed to be stable after scavenging. Therefore, it can be asserted that scavenging is a useful method for LS purification.
Improvement of Energy Estimator for KamLAND-Zen 800
Authors: Miyake Haruhiko
Published: May 2021

KamLAND-Zen 800 explores neutrinoless double beta decay(0vββ) of 136Xe. The experiment was started in January 2019 and data acquisition is going well. In the latest result of KamLAND-Zen 800 the most dominant background is 2vββ decay, which can be reduced by improvement of the detector energy resolution. In this study we aim to improve the energy resolution by optimizing the energy reconstruction method and reduce the 2vββ background by a factor of ~ 2/3.
Nanostructuring and intercrystalline adsorption of the workpiece surface during plastic deformation of metals
Authors: Petrov A P , Bespalov A V , Sokolov A V , Shlenskiy A G
Published: May 2021

In this paper it is shown that the combination of surface nanostructuring and subsequent plastic deformation can be a way to control the structure of the material and, accordingly, its mechanical properties by surface action.
The use of laser shock processing for extension of service life of critical units of aircraft engines after the foreign object damage
Authors: Sakhvadze G G , Pugachev M S , Sakhvadze Zh G
Published: May 2021

The authors study the change of the rate of growth of fatigue cracks that occur due to the damage of surface of an engine blade made of the alloy Ti-6Al-4V, previously processed by laser shockwaves, by foreign objects. The numerical study of the model of damaged laser-processed blade was performed by finite element method. The model developed took into consideration the residual stress fields that occurred due to the foreign object damage as well as the effect of the crack closure under compressive residual stresses. To cause the growth of fatigue cracks, the blade was stressed using real operation modes, including low-and high-cycle fatigue and the combination thereof. The residual stresses, previously inserted into laser shock processing blade surface, complicate the origin and growth of fatigue cracks after the foreign object damage, extending the service life of the blade and the entire engine.
Microstructure, fatigue strength and erosion resistance of MAX-phase embedded Ti-Si-B nanostructured coatings on Ti-6Al-4V
Authors: Teryaev D A , Shulov V A , Bytsenko O A , Lyakhovetskiy M A
Published: May 2021

Ti-Si-B nanostructured coatings were deposited on Ti-6Al-4V substrates by vacuum plasma processing with droplet separation. A composite Ti-Si-B cathode fabricated by self-propagating high temperature synthesis with subsequent hot pressing was used. The microstructure and mechanical properties of the obtained coatings were analysed by applying Auger-electron spectroscopy, X-ray diffraction and scanning electron microscopy methods accompanied by hardness measurements, fatigue strength and erosion resistance testing. It was established that Ti-Si-B nanostructured coating deposition leads to significant improvement of fatigue strength and erosion resistance of Ti-6Al-4V. A noticeable raise of the fatigue strength is attributed to presence of low dispersed Ti3SiB2 MAX-phase inclusions that suppress fatigue crack propagation.
Research Status and Development of Precision Analysis of CNC Machine Tools
Authors: Dou Yifan , Zhang Genbao , Ran Yan
Published: May 2021

Accuracy is a key quality characteristic of CNC machine tools, reflecting the pros and cons of machine tool performance. Accuracy is affected by performance failures of CNC machine tools, such as vibration, friction, and heat transfer. Therefore, it is difficult to accurately model and comprehensively analyse the accuracy of the machine tool by studying the influence of certain factors on the accuracy of the CNC machine tool in isolation, which makes it difficult to find out the problems in the design or manufacturing process. The article analyses the current status and research significance of domestic CNC machine tool accuracy, expounds the domestic and foreign research status of CNC machine tool accuracy modelling method and CNC machine tool accuracy comprehensive analysis, summarizes the existing problems and development trends of CNC machine tool accuracy research, and compares it based on the meta-action. The theoretical systematic modelling of the accuracy of CNC machine tools and the key issues of comprehensive evaluation of the accuracy of CNC machine tools combined with the meta-action chain provide insights and provide analytical methods for the design and manufacture of CNC machine tools.
Perovskite solar cell with improved performance passivated by all inorganic perovskite quantum dots
Authors: Cao Jia Xing , Shen Hui Feng , Cheng Lei , Zhao Wen Tao , Zhu Dong Huan , Sun Yan , Ni Bo
Published: May 2021

Improving the efficiency and stability of perovskite solar cells is the main direction of realizing their commercial application. Interface passivation is one of the most effective methods. Through interface passivation, on the one hand, the energy level of the device can be adjusted and the photoelectric conversion efficiency (PCE) of the device can be improved; on the other hand, materials that are not sensitive to the environment can be selected to improve the stability of the device. All inorganic perovskite quantum dots (QDs) have excellent environmental stability and are similar to the crystal structure of the absorbing layer of perovskite solar cells, so they have the potential for interface passivation. In this paper, two kinds of all inorganic perovskite QDs with different morphology, size and crystal structure were synthesized by hot injection method, which were used as the passivation layer of perovskite solar cells, and improved the device performance. The PCE of the device treated with CsPbBr3 QDs can reach as high as 20.45%, and has excellent environmental stability.
UAV 3D environment obstacle avoidance trajectory planning based on improved artificial potential field method
Authors: Yu Wenqiang , Lu Yonggeng
Published: May 2021

To address the inefficiency of the traditional artificial potential field method in complex environment for obstacle avoidance, the basic potential field function of the traditional artificial potential field method is improved, and the traditional spherical potential field is proposed to be improved to ellipsoidal potential field, and the improved algorithm is compared and simulated in MATLAB. The results show that the improved artificial potential field method satisfies the UAV to have high efficiency of safety and passability in obstacle avoidance trajectory planning in complex 3D environment.
The Effect on Carburizing Process on Microstructure and Properties of 20MnCr5 Gear Steel
Authors: Liang X. , Li X.J. , Lin X.Y. , Fan Z.Y. , Luo P. , Sun F.L. , Gao B.K. , Zhou T. , Du Q.N. , Xie H.S.
Published: May 2021

In this report, 20MnCr5 gear is characterized and analyzed under two carburizing heat treatment processes by optical microscope (OM) analysis, scanning electron microscope (SEM) analysis, X-ray diffraction (XRD) and Vickers hardness test. Results show that spherical and angular carbides can be obtained by a high concentration carburizing process for 20MnCr5 gear. Reheating and subsequent low-temperature tempering help refine the grains of the infiltration layer, reduce the residual austenite content in the permeable layer, and increase the thickness of the effective hardening layer.
Failure Analysis on Leakage and Perforation of Natural Gas Pipeline
Authors: Ju Jianbo , Du Liang , Meng Tao
Published: May 2021

CO2 corrosion is one of the most common corrosion forms in the process of oil and gas field development and oil and gas gathering and transportation. In the process of natural gas gathering and transportation, the problem of pipeline corrosion caused by CO2 is widespread, which often leads to serious local thinning, even perforation and fracture of the pipe body. Once it occurs, it will cause great economic losses and disastrous consequences to the actual production. Therefore, it is of great practical significance to study the mechanism of CO2 corrosion and analyze the influencing factors of CO2 corrosion in order to prevent the safety accidents and improve the efficiency of natural gas transportation. In this paper, a natural gas pipeline wall perforation failure analysis as an example, the sample from the natural gas pipeline corrosion product morphology and composition of micro analysis, and the CO2 corrosion mechanism, influencing factors and other aspects are described in detail.
Analysis of the Influence of Pit Unit Arrangement on the Drag Reduction Performance of Fish-scale Pits
Authors: Hou Jin-Ming , Shi Guang-Feng , Li Liang , Li hong-Da , Xia mingqiang
Published: May 2021

Apply Computational Fluid Dynamics (CFD) method to calculate the drag reduction effect of fish-scale pits with different arrangements under the same conditions. Through the analysis of wall shear stress, wall turbulence energy and axial velocity cloud diagram and velocity vector. It was found that the fish-scale pits can effectively reduce the shear stress and turbulent flow energy on the wall. At the same time, it was found that the bottom of the fish-scale pits formed tiny vortices flowing in the opposite direction. The “vortex cushion effect“ is combined with the “pushing effect“ caused by the friction generated by the bottom vortex, thereby reducing the friction. The research results show that the rhombus arrangement 2 can arrange a denser pit unit in the effective area to achieve a better drag reduction effect, and its drag reduction rate reaches 6.05%.
Experimental study of low-cycle fatigue of S30408 welded joints with strain strengthening
Authors: Si Jun , Ren Facai , Ren Bin
Published: May 2021

With the change of energy consumption structure, cryogenic liquids are increasingly widely used, such as liquefied natural gas (LNG), liquid hydrogen, liquid nitrogen, etc. Austenitic stainless steel is widely used in fabrication of cryogenic temperature pressure vessels as a kind of material with good lower temperature resistance. It is difficult to give full play to the high tensile strength and high plasticity reserve of austenitic stainless steel by using conventional design methods, which results in material waste and cost increase. The strain strengthening technology of austenitic stainless steel is the more effective method to realize the lightweight design and manufacture of cryogenic pressure vessel and reduce the cost. Fatigue damage is one of the typical failure modes of cryogenic pressure vessels. For the fatigue design of conventional pressure vessels, there are detailed standards, but there are few specific provisions for the fatigue design of strain strengthening pressure vessels. In this paper, experimental study on the low-cycle fatigue behavior of S30408 welded joints with 7% and 9% pre-tensile deformation were carried out.
Effect of process parameters on wall thinning of high strength 21-6-9 stainless steel tube in numerical control bending
Authors: Fang Jun , Ouyang Fang , Lu Shiqiang , Wang Kelu , Min Xuguang
Published: May 2021

Wall thinning, as one of the key defects determined directly the usability of the bent tube, should be strictly controlled. Elastic modulus changes with the plastic deformation and its influence the plastic forming quality of tube bending. To precisely predict the wall thinning of tube bending, a finite element (FE) model for numerical control (NC) bending of high strength 21-6-9 stainless steel tube (21-6-9-HS tube) was established considering the variation of elastic modulus. Using the model, the effects of process parameters on wall thinning of the 21-6-9-HS tube in NC bending were investigated. The results show that the variation of elastic modulus has no obvious effect on the change tendency of the wall thinning degree, but only increases the value of the wall thinning degree. The wall thinning degree enhances sharply at first, then occurs a platform deforming characteristics, and finally reduces abruptly from the bending section to the initial bending section, and it increases with the increase of the clearance of tube-bending die, the friction coefficient of tube-bending die and the friction coefficient of tube-wiper die or with the decrease of the clearance of tube-wiper die, but the increased degree is not significant in all conditions.
Influence of the North Branch of the Qingshuigou River on the Lower Reaches of Yellow River Based on Two-dimensional Numerical Model
Authors: Jiang Caodong , Ma Liangchao , Li Dongfeng , Zhang Hongwu , Li Zihao
Published: May 2021

The estuary regulation of the Yellow River is closely related to the regulation of the lower Yellow River. The flow and sediment entering the sea block the sediment entering the sea under the action of tidal rise and blocking sand, which has a significant impact on the flood control of the lower Yellow River. In the present study, there are many studies on the analysis of measured data and the empirical formula of inductive reasoning regression, and the use of two-dimensional mathematical model of water and sediment is still rare. In this study, based on the established mathematical model of marine water and sediment in the Yellow River estuary, the typical water and sediment conditions are selected to calculate the sediment movement and siltation erosion in the sea. The calculation results show that under the action of tide and blocking sand, the influence distance of the flow and sediment in the sea on the downstream river is about 90 km-110 km below the Luokou. The flow and sediment in the sea are mainly deposited in the range of 6-8 km along the direction of the flow in the sea near the entrance. The highest point of backwater is in the front of the blocking sand ridge. The backwater surface is relatively steep in the direction of the sea, and the backwater surface is relatively slow in the direction of the river.
Load balancing transmission technology of network communication based on phase spectrum compensation
Authors: Zhai Qian , Lu XingHua
Published: May 2021

In order to improve the load balance scheduling transmission ability of multi-frequency network communication in high-order nonlinear system, load balance design is needed. A load balance transmission method of multi-frequency network communication in high-order nonlinear system based on phase spectrum compensation is proposed. The time domain model of high-order nonlinear system multi-frequency network communication load is constructed by multi-frequency modulation phase spectrum compensation method. The feature detection of high-order nonlinear system multi-frequency network communication load is realized by high-order statistical feature connection identification and communication load balancing method. The autocorrelation constraint parameters of high-order nonlinear system multi-frequency network communication load are analyzed. The multi-dimensional array networking structure model of high-order nonlinear system multi-frequency network communication load is constructed by spatial spectral density analysis method. Combined with phase spectrum compensation and signal detection methods, the extracted high-order nonlinear system multi-frequency network communication load spectrum features are adaptively scheduled and filtered. In the wireless communication networking environment, load balance transmission of communication load in multi-frequency network of high-order nonlinear system is realized. The simulation results show that this method has better balance and lower error rate in multi-frequency network communication load balancing transmission, which improves the accuracy of multi-frequency network communication load balancing scheduling in high-order nonlinear systems.
Study on Properties of Flame-Retardant Plywood Made with Eucalyptus, Birch and Poplar Wood
Authors: Yin Chaolu , Zhang Xiang , Li Pingli , Fu Fuxin
Published: May 2021

In this work, the laboratory-made flame-retardant polyvinyl alcohol adhesive was used to prepare flame-retardant plywood made with eucalyptus, birch and poplar respectively, and the effect of tree species on the mechanical properties and flame-retardant properties of flame-retardant plywood was studied. The static bending strength data showed that the tree species had an obvious effect on the mechanical properties of the flame-retardant plywood, the flame-retardant plywood made with eucalyptus had the highest static bending strength, and the sample made with poplar had the lowest static bending strength. The results of the SBI test are consistent with the results of the LOI test, both indicated that the tree species had a significant effect on the flame-retardant properties of the flame-retardant plywood, the flame-retardant plywood made with poplar veneer has the highest LOI value, lowest FIGRA0.2MJ value and lowest THR
600s value.
Study on Performance of Cabin Air filters Under Different Work Conditions
Authors: Wei Shuhong , He Yongao , Yin Wei , Tian Cheng , Jiao Pengfei , Bian Jiachen
Published: May 2021

The in-vehicle air quality has increasingly attracted the attention of people. Hence, air filter performance under actual work conditions demonstrates remarkable significance. It is verified that the electrostatic adsorption can dramatically enhance the fractional efficiency of small-particle pollutants without increasing the pressure loss; as regard a lack of fractional efficiency test on the filter during the whole life cycle in current standards, the paper studied the tendency of filter’s fractional efficiency variation in the whole life cycle and discovered that fractional efficiency of small particles decreased first after increase due to the shielding of electrostatic charge; the tests on different air speed and area of filtered paper were carried out, showing that increasing the area of filtered paper can significantly lower the pressure loss and increase the filtration efficiency, which is of vital significance to provide the reference for further improving the performance of cabin air filter.
Study on Oxygen Reduction Method of Phosphorus-doped Hydrogenated Nano-silicon
Authors: Liu Danjuan , He Wei
Published: May 2021

In recent years, hydrogenated nano-silicon has attracted much attention due to its high specific energy density. However, the slow kinetic oxygen reduction reaction (ORR) and oxygen evolution reaction (ORE) reduce the efficiency of hydrogenation of nano-silicon and hinder its practical application. The development of non-precious catalysts with excellent performance and low price is of great significance to the development of hydrogenated nano-silicon. Among many hydrogenation nano-silicon catalysts, cobalt-based compounds have good ORR and ORE catalytic performance, and are rich in Co reserves and low in price. Especially doped compounds have excellent stability. In the thesis, three series of hydrogenated nano-silicon composite materials of Co-SrCO3/NC, Co-Nd/NC and Co-Ce/NC were successfully synthesized through heating reflow method and subsequent high-temperature calcination. XRD, Raman, XPS, TEM, nitrogen isothermal adsorption and desorption and other analytical methods were used to characterize the structure of the above composite materials. Through chemical tests, the composite materials were evaluated for the catalytic performance of ORR and ERR, and their structure-activity relationship was analyzed. The Co_SrC03/NC series composite materials were calcined at different temperatures. The results showed that the generated SrCO3 nanorods were embedded in the graphite shell and contacted with hydrogenated nano-silicon. In an oxygen-saturated 0.1MKOH solution, Co-SrCO3/NC series composites have excellent ORR/ORE catalytic activity, especially Co-SrCO3/NC-600 has more stable activity than precious metal catalysts of 20wt% Pt/C and Ir02. Sex. The air prepared with Co-SrCO3/NC-600 has better performance. During the in-depth study of 10mA_cnT2, Co-SrC03/NC-600 was used as the air to maintain a stable platform of 1.10V, and the platform of 20wt%Pt/C under the same conditions was 1.17V.
UWB localization algorithm based on BP neural network compensation extended Kalman filter
Authors: Kun Jin
Published: May 2021

When UWB technology is applied to indoor positioning, there will be a lot of noise interfering with its positioning accuracy. In order to improve the positioning accuracy, the improved extended incremental Kalman filtering algorithm and BP neural network algorithm are proposed to eliminate the positioning errors. In this paper, the extended incremental Kalman filter algorithm is first used to denoise the distance measured by UWB to reduce the errors caused by environment, equipment and other factors, then the classical Chan positioning algorithm is used to get the positioning results of tags, and finally the BP neural network algorithm is used to compensate the positioning results.
Failure Analysis of Stainless Steel EH Tubing Used in Power Plant
Authors: Yang Chao , Li Xiuneng , Wang Yunan , Hou Shuang , Sun Mingcheng
Published: May 2021

The EH fuel pipe of stainless steel used in a power plant was cracked. The crack and leakage of stainless steel fuel pipe were detected and analyzed by alloy composition analysis, EDS, microhardness and metallographic structure. Results show that the alloy components conform to the requirements of the standard stainless steel EH fuel pipe’s microstructure is normal, but EDS results show that Cl and S ions were detected in the crack aperture. The microhardness test found that the closer the hardness value is to the crack, the lower it is. Combined with the operating environment of EH tubing, the main reason for tubing cracking is that it absorbs moisture in the air and free Cl ions in a humid working environment, forming a corrosive medium. Under the action of working pressure and residual stress, stress corrosion cracking that expands from outside to inside occurs.
Prediction of the Number of Pure Electric Vehicles Based on the Extended GM(1,1) Model
Authors: Song Xuyang , Wang Yulu
Published: May 2021

The gray system theory is used to study the changes in the number of pure electric vehicles nationwide. According to the data on the number of pure electric vehicles in the country from 2016 to 2020, the original time series prediction model is established based on the GM(1,1) model. Using MATLAB to establish the original GM(1,1), new information GM(1,1) and metabolic GM(1,1), and compare them, and select the metabolic GM(1,1) with the smallest sum of squared errors for model performance Inspection and error analysis showed that the degree of fit was up to standard, and the predicted results were obtained. The prediction results show that the number of pure electric vehicles in my country will increase year by year from 2021 to 2023, and the number of pure electric vehicles in my country will exceed 10 million by the end of 2023.
Wheel Hub Automatic Production System Based on Industrial Robots
Authors: Zhang Bin , Lu Zongxue , Wang Qiang , Cui Shiyi , Jia Guangxin , Yang Jun
Published: May 2021

In this thesis, a control system for a wheel hub machining line based on a Fanuc robot, which includes adopting Siemens 300PLC as the main control unit, performing wheel circumferential positioning and center correction based on vision technology, and controlling the machine tool to perform real-time tool compensation based on the measured data, is researched and designed to achieve fully automatic unmanned wheel processing.
Sensitivity study of vibration responses on vehicle body to typical damages of ballastless track structures
Authors: Jiang Shaoxin , Zhang Kun
Published: May 2021

A method is proposed to investigate the sensitivity of the vibration responses on vehicle body to typical damages of ballastless track structures based on a coupled rigid vehicle body and flexible track model. Firstly, a coupled rigid vehicle body and flexible track model is established by combining SIMPACK and ANSYS software, and the reasonableness of the model is verified by coupling analysis. And then, the sensitivity of the vibration signals from different parts of the vehicle body to the typical damages of the ballastless track is investigated by simulating several typical damages on the flexible track model, and the feasibility of inversion of track damage based on the responses on vehicle body is investigated. The results show that a reasonable coupled vehicle-track model can be established by combining the finite element and multi-body dynamics method. The changes in the vibration responses of the vehicle body can reflect the typical track damages such as the loosening of rail fasteners, the debonding of CA mortar layer and cracks in track plate. The wheel-set axle box is the optimal location for installing vertical vibration sensors.
Discussion on intelligent monitoring technology of railway wagon
Authors: Ma Guiping , Deng Cheng-Yao , Li Dong
Published: May 2021

In the actual transportation process, a series of bad conditions could occur due to the unexpected opening of the door. This paper introduced the current situation of railway transportation process; analyzed the advantages and necessity of intelligent monitoring system; Then taking the boxcar as an example, the basic process of intelligent real-time detection is proposed; and the problems that may need to be considered in the actual implementation process are summarized.
Real-time high-precision location and mapping system based on NDT of the large scene
Authors: Liang Yu , Luo Jie , Liu Sijia , Luo Haoru
Published: May 2021

The traditional lidar registration algorithm has good stability and high precision when carrying out large-scale simultaneous localization and mapping. However, in complex and changeable environments such as outdoor, severe occlusion, or electronic interference, the signal is easily affected, and the positioning accuracy cannot be guaranteed. To solve the above problems, a high-precision localization method based on laser-point cloud NDT (Normal Distributions Transform) is proposed in this paper, which makes full use of the mean and variance characteristics of NDT registration of the midpoint cloud, and the proposed method is added into the complete framework of SLAM (Simultaneous Localization and Mapping). The algorithm proposed in this paper was verified on the “Wuling Electric Vehicle“ platform. The experimental results were showed that the proposed algorithm could effectively avoid the influence caused by signal weakening, which improved the positioning accuracy. It also had stronger robustness and better tracking performance.
Research on derivation of calculation formula and application scope of simplified formula about camber of gantry crane cantilever based on coordinate transformation
Authors: Kuang Xiangning , Hu Haoliang , Chen Feng , Ding Gaoyao , Zhang Zhijian , Yu Dongqiang , Qiu Faju , Hu Jinxiu
Published: May 2021

For the gantry crane with cantilever, its cantilever camber value has a great influence on the operation and stop reliability of the lifting trolley, which is an important performance index of the bearing structure of the equipment. When the height of the outriggers on both sides of the gantry crane is inconsistent, the vertical height difference measured at the cantilever end is not the actual upwarping of the equipment, and the numerical change caused by the height difference of the outriggers needs to be corrected. In this paper, the calculation formula of the upwarping degree based on the transformation of coordinate system is proposed, which can accurately express the upwarping degree of the cantilever. Based on this, the simplified formula is derived and the scope of application is limited, which is suitable for the inspection and calculation in engineering practice, and the error is within the allowable range.