bluuebunny/crossref_metadata_2025 huggingface dataset:
A quasi-one-dimensional study on global characteristics of tube train flows
Authors: Hou Zihao , Zhu Yujian , Bo Jinglong , Yang Jiming
Published: February 2022

The global characteristics of tube train flows under wide ranges of blockage ratios and train speeds are comprehensively investigated by quasi-one-dimensional numerical simulation and theoretical analysis. The established quasi-one-dimensional model for the tube train flow and the numerical method are both proven to be reliable and efficient. Investigation reveals the typical patterns of both inviscid and viscous flows. The transition limits for these flow patterns are determined. The flows tend to be unstarted when the train moves at a high subsonic speed or a low supersonic speed and tend to be started otherwise. The transition limits between started and unstarted modes do not vary much between inviscid and viscous flows, which allows the use of analytical inviscid criteria in approximate estimation of the start/unstart state of the viscous flow. Between the supersonic isentropic limit and the Kantrowitz limit lies a dual-solution area. Which solution the flow follows depends on how the attempted cruise speed of the train is reached; a large acceleration tends to induce a started flow. The unstarted inviscid tube train flow appears to be self-similar as the train suddenly moves at a constant speed. This flow involves a precursor shock wave in front of the train and a secondary shock wave on or behind the train at the same time. By contrast, the unstarted viscous flow eventually remains a steady laminar structure that moves with the train after a sufficiently long process of development. In the stabilized flow, the precursor shock wave only occurs in the supersonic case, and the secondary shock wave only occurs in the subsonic case. For both inviscid and viscous flows, the unstarted flow can be divided into two submodes according to whether the secondary shock wave detaches from the train. Aerodynamic drag on the train is strongly correlated with the flow modes. The drag in unstarted flow increases with train speed, while the drag coefficient peaks at the secondary shock attach–detach limit. The wall transport effects cause larger drag but do not change its overall features.
Evolution of jets during drop impact on a deep liquid pool
Authors: Das Santanu Kumar , Dalal Amaresh , Breuer Michael , Biswas Gautam
Published: February 2022

The impact of a liquid drop on a liquid pool has been widely investigated. The transition regimes between coalescence and splashing of drops include jet formation with single or multiple secondary drops. One of the main features in this regime is the formation of a central liquid jet followed by breakup of the jet in the form of drops. Earlier studies have shown that the diameter of the secondary drop lies between 0.58 and 0.94 times the diameter of the impacting drop. We perform investigations based on a coupled level-set and volume-of-fluid method to elucidate the earlier observations. The investigations reveal the creation of a variety of secondary drops depending on the impact conditions. The present study also reveals that secondary drops larger than the initial drop can be obtained at higher impact velocities. We identify the importance of cavity shapes on the formation of jets and the pertaining parameters that are responsible for drop ejection.
High-resolution vibronic spectroscopy of a single molecule embedded in a crystal
Authors: Zirkelbach Johannes , Mirzaei Masoud , Deperasińska Irena , Kozankiewicz Boleslaw , Gurlek Burak , Shkarin Alexey , Utikal Tobias , Götzinger Stephan , Sandoghdar Vahid
Published: February 2022

Vibrational levels of the electronic ground states in dye molecules have not been previously explored at a high resolution in solid matrices. We present new spectroscopic measurements on single polycyclic aromatic molecules of dibenzoterrylene embedded in an organic crystal made of para-dichlorobenzene. To do this, we use narrow-band continuous-wave lasers and combine spectroscopy methods based on fluorescence excitation and stimulated emission depletion to assess individual vibrational linewidths in the electronic ground state at a resolution of ∼30 MHz dictated by the linewidth of the electronic excited state. In this fashion, we identify several exceptionally narrow vibronic levels with linewidths down to values around 2 GHz. Additionally, we sample the distribution of vibronic wavenumbers, relaxation rates, and Franck–Condon factors, in both the electronic ground and excited states for a handful of individual molecules. We discuss various noteworthy experimental findings and compare them with the outcome of density functional theory calculations. The highly detailed vibronic spectra obtained in our work pave the way for studying the nanoscopic local environment of single molecules. The approach also provides an improved understanding of the vibrational relaxation mechanisms in the electronic ground state, which may help create long-lived vibrational states for applications in quantum technology.
Analysis of motion characteristics and synchronous error based on vacuum switch module with integrated operation of double-break
Authors: Guo Xingyu , Huang Zhihui , Liang Deshi , Zou Jiyan
Published: February 2022

Multi-break vacuum circuit breakers (VCBs) is an important research direction for scaling VCBs up to a higher voltage level. A VCB module with an integrated operation of double-break is designed to increase synchronization of multi-break VCBs, and the synchronization error beyond the mechanical structure is eliminated. First, the mathematical model and motion model of the transmission system were established. Then the motion characteristics and the double-break synchronization error of the module were analyzed. Finally, the prototype was designed and manufactured for parameter testing and trajectory verification. The analysis shows that the displacement transmission ratio increases with the increase in the transmission pull rod length and the initial closing angle. The length of the transmission pull rod has little effect on the displacement transmission ratio, while the initial closing angle has a major effect on it. The simulation results show that the transmission system can realize maximum control of the double-break mechanical error to within 0.59 mm with the IT12 level and the mechanical error obtained by the root sum squared method can be within 0.3 mm. The maximum mechanical error can be controlled to within 0.06 mm by improving the tolerance and fit of moving pairs to the IT6 level. The experimental results reveal that the maximum mechanical error of double-break’s clearance between open contacts is 0.49 mm and the synchronization error is not greater than ±0.1 ms. It is proved that the module can realize high precision synchronous operation. This study provides a practical design idea and processing requirements for the control of synchronous errors of multi-break VCBs.
Genetic analysis of cancer drivers reveals cohesin and CTCF as suppressors of PD-L1
Authors: Oreskovic Ena , Wheeler Emily C. , Mengwasser Kristen E. , Fujimura Eric , Martin Timothy D. , Tothova Zuzana , Elledge Stephen J.
Published: February 2022

Significance

The PD-1/PD-L1 immunoinhibitory axis plays a key role in immune evasion of cancer cells, and therapies targeting PD-1/PD-L1 show high efficacy in certain cancer types. Understanding how cancer drivers regulate immune surveillance will enable development of novel therapeutic strategies targeting cancer-mediated immune evasion, and identification of new biomarkers of response. Here, we utilized genetic screening with a curated library of 500 tumor suppressor genes to identify cohesin subunits and CTCF among the most significant suppressors of PD-L1. We report upregulation of additional key immune-regulatory molecules PD-L2 and MHC-I, and describe transcriptional consequences of loss of the STAG2 cohesin subunit, including an induction of IFN and NF-κB responses, which have implications for biology and treatment of cohesin-deficient tumors.
Ti6Al4V matrix composites fabricated by laser powder bed fusion in dilute nitrogen
Authors: Zhu Lei , Zhang Kaiwang , Fan Shuqian , Wei Wenhou
Published: February 2022

In situ synthesised TiN reinforced Ti6Al4V matrix composites were fabricated via laser powder bed fusion (L-PBF) in an atmosphere of 10vol.-% N2 and 90vol.-% Ar based on novel gas–liquid reaction between N2 and Ti6Al4V melt pool. With lower laser energy density (LED), the microstructures of the composites mainly consisted of acicular α′ martensites, while the martensites were shortened and coarsened with increasing LED. The X-ray diffraction analysis demonstrated that the interstitial solid solution of N was formed in the Ti lattice. High-resolution transmission electron microscopy analysis confirmed the generation of TiN. The microhardness, yield strength, ultimate strength and plasticity of the composites initially increased and then decreased with increasing LED. The strengthening mechanisms of the composites were elucidated.
Tricellulin secures the epithelial barrier at tricellular junctions by interacting with actomyosin
Authors: Cho Yuma , Haraguchi Daichi , Shigetomi Kenta , Matsuzawa Kenji , Uchida Seiichi , Ikenouchi Junichi
Published: February 2022

The epithelial cell sheet functions as a barrier to prevent invasion of pathogens. It is necessary to eliminate intercellular gaps not only at bicellular junctions, but also at tricellular contacts, where three cells meet, to maintain epithelial barrier function. To that end, tight junctions between adjacent cells must associate as closely as possible, particularly at tricellular contacts. Tricellulin is an integral component of tricellular tight junctions (tTJs), but the molecular mechanism of its contribution to the epithelial barrier function remains unclear. In this study, we revealed that tricellulin contributes to barrier formation by regulating actomyosin organization at tricellular junctions. Furthermore, we identified α-catenin, which is thought to function only at adherens junctions, as a novel binding partner of tricellulin. α-catenin bridges tricellulin attachment to the bicellular actin cables that are anchored end-on at tricellular junctions. Thus, tricellulin mobilizes actomyosin contractility to close the lateral gap between the TJ strands of the three proximate cells that converge on tricellular junctions.
Low energy inelastic electron scattering from carbon monoxide: II. Excitation of the b3Σ+, j3Σ+, B1Σ+, C1Σ+ and E1Π Rydberg electronic states
Authors: Zawadzki Mateusz , Khakoo Murtadha A , Sakaamini Ahmad , Voorneman Logan , Ratkovich Luka , Mašín Zdeněk , Dora Amar , Laher Russ , Tennyson Jonathan
Published: February 2022

In this second part of a two part paper (first part: Zawadzki et al (2020 J. Phys. B: At. Mol. Opt. Phys.
53 165201)) we present differential scattering cross sections for excitation of several Rydberg electronic states of carbon monoxide by electron impact. The first part concerned the low-lying valence states of CO. In the present study cross sections are obtained experimentally using low-energy electron energy-loss spectroscopy and theoretically using the R-matrix method. Incident electron energies range from near-threshold of 12.5 eV to 20 eV while the scattering angles range from 20° to 120°. The R-matrix calculations use three distinct close-coupling models and their results are compared to available experimental and theoretical cross sections. The overall comparison leads to significantly improved description of the excitation cross sections for this target.
Energetic Au ion beam implantation of ZnO nanopillars for optical response modulation
Authors: Macková Anna , Malinský Petr , Jagerová Adéla , Mikšová Romana , Lalik Ondrej , Nekvindová Pavla , Mistrík Jan , Marvan Petr , Sofer Zdenek , Holý Václav , Schutter Jan David , Kentsch Ulrich , Azarov Alexander , Galeckas Augustinas
Published: February 2022

Nanopillars of ZnO were implanted with Au-400 keV ions at various ion fluences from 1 × 1015 cm−2 to 1 × 1016 cm−2 and subsequently annealed at 750 °C for 15 min in order to reduce the implantation damage and to support Au nanoparticle (NP) aggregation. It was found that implantation-induced effects and thermal effects influence the Au NP coalescence as well as the quality of the ZnO nanopillars. Rutherford Back-Scattering spectrometry (RBS) showed the broader Au-depth profiles than it was theoretically predicted, but the Au-concentration maximum agrees well with prediction taking into account the effective ZnO layer density. The implantation at the higher fluences induced the morphology modification of the nanopillar layer evidenced by RBS and scanning electron microscopy (SEM). An indirect evidence of this effect was given by optical ellipsometry due to gradual refractive index changes in the ZnO nanopillars with the increased Au-ion fluence. Optical characterization of the Au-implanted and annealed nanopillars performed by means of photoluminescence (PL) and diffuse-reflectance spectroscopy (DRS) evidenced the surface plasmon resonance (SPR) activity of the embedded Au NPs. The SPR-enhanced scattering and PL emission observed in the spectral range 500–650 nm are ascribed to Au NPs or more complex Au-clusters. In addition, the ellipsometry measurements of extinction coefficient are found to corroborate well results from DRS, both indicating increase of SPR effect with the increase of Au-ion fluence and after the post-annealing.
A novel INS/ADS integrated navigation method based on INS error model-aided unbiased converted measurement
Authors: Li Zhenwei , Cheng Yongmei , Zhang Xiaodong , Zhang Yachong , Yang Shaohua
Published: February 2022

In the inertial navigation system (INS)/ air data system (ADS) integrated navigation system, the measurements of INS and ADS need to be converted to a unified coordinate for fusion. However, the sensor noises cause serious conversion bias in the direct measurement conversion method. In this paper, a novel INS/ADS integrated navigation method based on INS error model-aided unbiased converted measurement (IEM-UCM) is proposed. First, the IEM-UCM model of ADS data from spherical frame to navigation frame is developed, which exploits the INS error model to calculate the compensation factors. Subsequently, the noise covariance of the converted measurement is derived. Finally, a standard Kalman filter (KF) is implemented for INS/ADS integrated navigation. The simulation results validate the effectiveness of the proposed method in terms of the unbiasedness and consistency of the converted measurement. The root mean square error values indicate that the proposed method outperforms the existing methods in navigation accuracy.
A review on III–V compound semiconductor short wave infrared avalanche photodiodes
Authors: Liang Yan , Perumal Veeramalai Chandrasekar , Lin Guochen , Su Xiangbin , Zhang Xiaoming , Feng Shuai , Xu Yingqiang , Li Chuanbo
Published: February 2022

The on-chip avalanche photodiodes (APDs) are crucial component of a fully integrated photonics system. Specifically, III–V compound APD has become one of the main applications of optical fiber communication reception due to adaptable bandgap and low noise characteristics. The advancement of structural design and material choice has emerged as a means to improve the performance of APDs. Therefore, it is inevitable to review the evolution and recent developments on III–V compound APDs to understand the current progress in this field. To begin with, the basic working principle of APDs are presented. Next, the structure development of APDs is briefly reviewed, and the subsequent progression of III–V compound APDs (InGaAs APDs, Al
x
In1−x
As
y
Sb1−y
APDs) is introduced. Finally, we also discuss the key issues and prospects of Al
x
In1−x
As
y
Sb1−y
digital alloy avalanche APDs that need to be addressed for the future development of ≥2 μm optical communication field.
Size dependent effects of two phase viscoelastic medium on damping vibrations of smart nanobeams: an efficient implementation of GDQM
Authors: Naderi Ali , Behdad Shahin , Fakher Mahmood
Published: February 2022

This paper studies the dynamics of nonlocal piezo-magnetic nanobeams (PMNBs) embedded in the local/nonlocal viscoelastic medium through the consistent and paradox-free model of the nonlocal theory. Besides, to perform the dynamic analysis, an exact solution and an efficient approach of generalized differential quadrature method (GDQM) are introduced. Since the size-dependency of the uniform loads is wrongly neglected by the nonlocal elasticity in differential form, the size-dependency of piezo-magnetic load is applied through the two-phase theory. Also, size dependency of the viscoelastic medium is accurately applied and examined through the solutions presented employing the differential two-phase theory and satisfying the constitutive boundary conditions. In this regard, the two-phase resultant equations of motions together with boundary conditions including the constitutive ones related to two-phase PMNB and the two-phase medium are attained. To confirm the credibility and efficiency of the extracted equations as well as presented solution procedures, several analogical studies are accomplished, and it is shown that the results obtained from the differential relations are reliable and consistence with those extracted from the integral nonlocal relations. It is shown that the present approach of the GDQM simplifies the solution procedures of the nonlocal problems and improves the precisions in the cases close to the pure nonlocal state. The presented results emphasize that the size-dependency of viscoelastic medium, external electric, and magnetic loads play significant roles on the vibration characteristics, and therefore it must be considered based on two-phase theory. The available results can be helpful to achieve an excellent design of smart nanobeams embedded in viscoelastic medium.
Phase diagram of quantum generalized Potts-Hopfield neural networks
Authors: Fiorelli Eliana , Lesanovsky Igor , Müller Markus
Published: February 2022

We introduce and analyze an open quantum generalization of the q-state Potts-Hopfield neural network (NN), which is an associative memory model based on multi-level classical spins. The dynamics of this many-body system is formulated in terms of a Markovian master equation of Lindblad type, which allows to incorporate both probabilistic classical and coherent quantum processes on an equal footing. By employing a mean field description we investigate how classical fluctuations due to temperature and quantum fluctuations effectuated by coherent spin rotations affect the ability of the network to retrieve stored memory patterns. We construct the corresponding phase diagram, which in the low temperature regime displays pattern retrieval in analogy to the classical Potts-Hopfield NN. When increasing quantum fluctuations, however, a limit cycle phase emerges, which has no classical counterpart. This shows that quantum effects can qualitatively alter the structure of the stationary state manifold with respect to the classical model, and potentially allow one to encode and retrieve novel types of patterns.
Physical aspects of cnoidal waves in non-thermal electron-beam plasma systems
Authors: Mehdipoor Mostafa , Asri Mehdi
Published: February 2022

The effects of electron beam and non-thermal electrons on ion-acoustic cnoidal waves (IACWs) structure in a two-fluid plasma system are investigated. A Kappa-Cairns type distribution is assumed for the background electrons. The Korteweg–de Vries (K-dV) equation is obtained by employing reductive perturbation technique and the analytical solution of K-dV equation is derived by employing the Sagdeev pseudo-potential approach. It is seen that in the presence of the electron beam, four modes can exist in this plasma model. In this study, it is observed that only two modes are real in all cases. Furthermore, it is found that the characteristics of the ion-acoustic cnoidal wave depend strongly on the electron beam parameters (via

ν

and

U

0

) as well as the non-thermal indexes for the plasma electrons (via

κ

and

α

).
Traceable spectral interferometry for length measurement
Authors: Lancaster A J , O’Connor D
Published: February 2022

Spectral interferometry is becoming a popular method of performing dimensional measurements, e.g. of surfaces, but such devices require pre-calibration of their spectrometers to achieve traceability. The use of a spectral lamp and imaging spectrometer to perform inherently traceable distance measurements using spectral interferometry, without the need for external calibration, is proposed and its experimental feasibility demonstrated. Initial experiments show measurements over a working range of 200 µm. The estimated standard uncertainty of the distance measurements is 0.6 nm, corresponding to an expanded uncertainty of 1.2 nm at k = 2.
Removal of movement-induced EEG artifacts: current state of the art and guidelines
Authors: Gorjan Dasa , Gramann Klaus , De Pauw Kevin , Marusic Uros
Published: February 2022

Abstract

Objective: Electroencephalography (EEG) is a non-invasive technique used to record cortical neurons’ electrical activity using electrodes placed on the scalp. It has become a promising avenue for research beyond state-of-the-art EEG research that is conducted under static conditions. EEG signals are always contaminated by artifacts and other physiological signals. Artifact contamination increases with the intensity of movement. Approach: In the last decade (since 2010), researchers have started to implement EEG measurements in dynamic setups to increase the overall ecological validity of the studies. Many different methods are used to remove non-brain activity from the EEG signal, and there are no clear guidelines on which method should be used in dynamic setups and for specific movement intensities. Main results: Currently, the most common methods for removing artifacts in movement studies are methods based on independent component analysis. However, the choice of method for artifact removal depends on the type and intensity of movement, which affects the characteristics of the artifacts and the EEG parameters of interest. When dealing with EEG under non-static conditions, special care must be taken already in the designing period of an experiment. Software and hardware solutions must be combined to achieve sufficient removal of unwanted signals from EEG measurements. Significance: We have provided recommendations for the use of each method depending on the intensity of the movement and highlighted the advantages and disadvantages of the methods. However, due to the current gap in the literature, further development and evaluation of methods for artifact removal in EEG data during locomotion is needed.
Exploring dynamic functional connectivity alterations in the preclinical stage of Alzheimer’s disease: an exploratory study from SILCODE
Authors: Yang Fan , Jiang Xueyan , Yue Feng , Wang Luyao , Boecker Henning , Han Ying , Jiang Jiehui
Published: February 2022

Objective. Exploring functional connectivity (FC) alterations is important for the understanding of underlying neuronal network alterations in subjective cognitive decline (SCD). The objective of this study was to prove that dynamic FC can better reflect the changes of brain function in individuals with SCD compared to static FC, and further to explore the association between FC alterations and amyloid pathology in the preclinical stage of Alzheimer’s disease. Approach. A total of 101 normal control (NC) subjects, 97 SCDs, and 55 cognitive impairment (CI) subjects constituted the whole-cohort. Of these, 29 NCs and 52 SCDs with amyloid images were selected as the sub-cohort. First, independent components (ICs) were identified by IC analysis and static and dynamic FC were calculated by pairwise correlation coefficient between ICs. Second, FC alterations were identified through group comparison, and seed-based dynamic FC analysis was done. Analysis of variance was used to compare the seed-based dynamic FC maps and measure the group or amyloid effects. Finally, correlation analysis was conducted between the altered dynamic FC and amyloid burden. Main results. The results showed that 42 ICs were revealed. Significantly altered dynamic FC included those between the salience/ventral attention network, the default mode network, and the visual network. Specifically, the thalamus/caudate (IC 25) drove the hub role in the group differences. In the seed-based dynamic FC analysis, the dynamic FC between the thalamus/caudate and the middle temporal/frontal gyrus was observed to be higher in the SCD and CI groups. Moreover, a higher dynamic FC between the thalamus/caudate and visual cortex was observed in the amyloid positive group. Finally, the altered dynamic FC was associated with the amyloid global standardized uptake value ratio (SUVr). Significance. Our findings suggest SCD-related alterations could be more reflected by dynamic FC than static FC, and the alterations are associated with global SUVr.
SQNN: a spike-wave index quantification neural network with a pre-labeling algorithm for epileptiform activity identification and quantification in children
Authors: Yu Yifei , Chen Yehong , Li Yuanxiang , Gao Zaifen , Gai Zhongtao , Zhou Yunqing
Published: February 2022

Objective. Electrical status epilepticus during slow sleep (ESES) is a phenomenon identified by strong activation of epileptiform activity in the electroencephalogram (EEG) during sleep. For children disturbed by ESES, spike-wave index (SWI) is defined to quantify the epileptiform activity in the EEG during sleep. Accurate SWI quantification is important for clinical diagnosis and prognosis. To quantify SWI automatically, a deep learning method is proposed in this paper. Approach. Firstly, a pre-labeling algorithm (PreLA) composed of the adaptive wavelet enhanced decomposition and a slow-wave discrimination rule is designed to efficiently label the EEG signal. It enables the collection of large-scale EEG dataset with fine-grained labels. Then, an SWI quantification neural network (SQNN) is constructed to accurately classify each sample point as normal or abnormal and to identify the abnormal events. SWI can be calculated automatically based on the total duration of abnormalities and the length of the signal. Main results. Experiments on two datasets demonstrate that the PreLA is effective and robust for labeling the EEG data and the SQNN accurately and reliably quantifies SWI without using any thresholds. The average estimation error of SWI is 3.12%, indicating that our method is more accurate and robust than experts and previous related works. The processing speed of SQNN is 100 times faster than that of experts. Significance. Deep learning provides a novel approach to automatic SWI quantification and PreLA provides an easy way to label the EEG data with ESES syndromes. The results of the experiments indicate that the proposed method has a high potential for clinical diagnosis and prognosis of epilepsy in children.
NSTX-U theory, modeling and analysis results
Authors: Guttenfelder W. , Battaglia D.J. , Belova E. , Bertelli N. , Boyer M.D. , Chang C.S. , Diallo A. , Duarte V.N. , Ebrahimi F. , Emdee E.D. , Ferraro N. , Fredrickson E. , Gorelenkov N.N. , Heidbrink W. , Ilhan Z. , Kaye S.M. , Kim E.-H. , Kleiner A. , Laggner F. , Lampert M. , Lestz J.B. , Liu C. , Liu D. , Looby T. , Mandell N. , Maingi R. , Myra J.R. , Munaretto S. , Podestà M. , Rafiq T. , Raman R. , Reinke M. , Ren Y. , Ruiz J. Ruiz , Scotti F. , Shiraiwa S. , Soukhanovskii V. , Vail P. , Wang Z.R. , Wehner W. , White A.E. , White R.B. , Woods B.J.Q. , Yang J. , Zweben S.J. , Banerjee S. , Barchfeld R. , Bell R.E. , Berkery J.W. , Bhattacharjee A. , Bierwage A. , Canal G.P. , Chen X. , Clauser C. , Crocker N. , Domier C. , Evans T. , Francisquez M. , Gan K. , Gerhardt S. , Goldston R.J. , Gray T. , Hakim A. , Hammett G. , Jardin S. , Kaita R. , Koel B. , Kolemen E. , Ku S.-H. , Kubota S. , LeBlanc B.P. , Levinton F. , Lore J.D. , Luhmann N. , Lunsford R. , Maqueda R. , Menard J.E. , Nichols J.H. , Ono M. , Park J.-K. , Poli F. , Rhodes T. , Riquezes J. , Russell D. , Sabbagh S.A. , Schuster E. , Smith D.R. , Stotler D. , Stratton B. , Tritz K. , Wang W. , Wirth B.
Published: February 2022

The mission of the low aspect ratio spherical tokamak NSTX-U is to advance the physics basis and technical solutions required for optimizing the configuration of next-step steady-state tokamak fusion devices. NSTX-U will ultimately operate at up to 2 MA of plasma current and 1 T toroidal field on axis for 5 s, and has available up to 15 MW of neutral beam injection power at different tangency radii and 6 MW of high harmonic fast wave heating. With these capabilities NSTX-U will develop the physics understanding and control tools to ramp-up and sustain high performance fully non-inductive plasmas with large bootstrap fraction and enhanced confinement enabled via the low aspect ratio, high beta configuration. With its unique capabilities, NSTX-U research also supports ITER and other critical fusion development needs. Super-Alfvénic ions in beam-heated NSTX-U plasmas access energetic particle (EP) parameter space that is relevant for both α-heated conventional and low aspect ratio burning plasmas. NSTX-U can also generate very large target heat fluxes to test conventional and innovative plasma exhaust and plasma facing component solutions. This paper summarizes recent analysis, theory and modelling progress to advance the tokamak physics basis in the areas of macrostability and 3D fields, EP stability and fast ion transport, thermal transport and pedestal structure, boundary and plasma material interaction, RF heating, scenario optimization and real-time control.
Full conversion from ohmic to runaway electron driven current via massive gas injection in the TCV tokamak
Authors: Decker J. , Papp G. , Coda S. , Duval B.P. , Sheikh U. , Blanchard P. , Choi D. , Galperti C. , Calacci L. , Carnevale D. , Ficker O. , Gobbin M. , Labit B. , Macusova E. , Mlynar J. , Plyusnin V. , Sauter O. , the TCV Team  , the EUROfusion MST1 Team
Published: February 2022

Full conversion from ohmic to runaway electron (RE) driven current was observed in the tokamak à configuration variable (TCV) following massive injection of neon through a disruption mitigation valve into a low-density limited circular plasma. Following a partial disruption, a stable 200 kA RE beam is maintained for more than 1 s. Controlled ramp-down of the RE beam with adjustable decay rate was demonstrated. Control of the beam vertical position was achieved down to a RE current of 20 kA. RE beam formation is observed in elongated plasma configurations up to κ = 1.5. A reproducible scenario for RE beam generation without loss of circulating current is of particular interest for disruption modelling applications.
Production and transport modelling of Po-210 in DEMO reactor
Authors: Chiovaro P. , Quartararo A. , Basile S. , Ciattaglia S. , Di Maio P.A. , Moro F. , Moscato I. , Spagnuolo G.A.
Published: February 2022

One of the generic designs of the nuclear fusion DEMO reactor proposed by the EUROfusion consortium foresees the development of a tritium breeding blanket (BB) relying on the use of the liquid-metal PbLi eutectic alloy as both neutron multiplier and tritium breeder, namely the water-cooled lithium lead (WCLL) BB, whose strengths and weaknesses are well known. This paper focuses the attention on one of the possible disadvantages of such a technology: the production of the highly radiotoxic radionuclide 210Po, which could become a safety issue to be accounted for. The 210Po concentration within the PbLi circuit has been assessed by solving a modified version of Bateman’s equations to consider the alloy circulation, so a one-dimensional convective fluid-dynamic model has been set up. Nuclear quantities have been evaluated by Monte Carlo neutron transport analyses using MCNP code and adopting a fully heterogeneous model of DEMO equipped with the WCLL BB. Moreover, rough sensitivity analyses have been performed to assess the influence on the results of the uncertainties related to the 209Bi radiative-capture cross section and the initial concentration of this nuclide which is present in the PbLi as an impurity. Results obtained have been critically discussed and some safety issues have been addressed to evaluate the possible hazard in case of a leak of PbLi accident.
Two price regimes in limit order books: liquidity cushion and fragmented distant field
Authors: Krause Sebastian M , Jungblut Edgar , Guhr Thomas
Published: February 2022

The distribution of liquidity within the limit order book is essential for the impact of market orders on the stock price and the emergence of price shocks. Limit orders are characterized by stylized facts: the number of inserted limit orders declines with the price distance from the quotes following a power law and limit order lifetimes and volumes are power law distributed. Strong dependencies among these quantities add to the complexity of limit order books. Here, we analyze the limit order book in the dimensions of price, time, limit order lifetime and volume altogether. This allows us to identify regularities that are not visible in marginal distributions. Particularly, we find that the limit order book is divided into two regimes. Around the quotes, we find a densely filled regime with mostly short living limit orders closely adapting to the price. Far away from the quotes, we find a sparse filling with long living limit orders, mostly inserted at particular times of the day being prone to flash crashes. We determine the characteristics of those two regimes and point out the main differences. Based on our research, we propose a model for simulating the regime around the quotes.
Ising spin ladder with trimer rungs and next-nearest-neighbor coupling: frustration in physics and agent models
Authors: Sznajd Jozef
Published: February 2022

The extended model of two-leg Ising spin ladder with trimer rungs and next nearest neighbor interaction (NNN) in an external magnetic field is studied using the transfer matrix and linear renormalization group methods. In the standard version (with the same only nearest-neighbor interactions in both legs), such a ladder exhibits very interesting behavior—a frustration driven extremely sharp phase crossover at finite temperature that resembles a phase transition, impossible in one dimension. It is shown that in all considered cases with different interactions in each leg (asymmetric ladder), with NNN interactions and in the presence of small external field, such a crossover takes place when the point at which the effective interleg coupling vanishes coincides with the point at which the interleg correlation function exhibits an inflection point accompanied by the specific heat maximum. A hypothesis is formulated to describe an abrupt change in political view of the people where it is not necessary to resort to a concept of a phase transition, controversial for social systems. In some cases, this phenomenon can be understood as a phase crossover triggered by the level of frustration. The source of this frustration is proposed as an internal conflict between two areas of attitudes of the society members, personal and economic, which are shaped by personality traits possibly modified by life experience.
Scaling of population resilience with dispersal length and habitat size
Authors: Crespo-Miguel Rodrigo , Jarillo Javier , J Cao-García Francisco
Published: February 2022

Environmental fluctuations can create population-depleted areas and even extinct areas for the population. This effect is more severe in the presence of the Allee effect (decreasing growth rate at low population densities). Dispersal inside the habitat provides a rescue effect on population-depleted areas, enhancing the population resilience to environmental fluctuations. Habitat reduction decreases the effectiveness of the dispersal rescue mechanism. We report here how the population resilience to environmental fluctuations decreases when the dispersal length or the habitat size are reduced. The resilience reduction is characterized by a decrease of the extinction threshold for environmental fluctuations. The extinction threshold is shown to scale with the ratio between the dispersal length and the scale of environmental synchrony, i.e. it is the dispersal connection between non-environmentally-correlated regions that provides resilience to environmental fluctuations. Habitat reduction also decreases the resilience to environmental fluctuations, when the habitat size is similar to or smaller than the characteristic dispersal distances. The power laws of these scaling behaviors are characterized here. Alternative scaling functions with spatial scales of population synchrony are found to fit the simulations worse. These results support the dispersal length as the critical scale for extinction induced by habitat reduction.
Critical points in the CP

N−1 model
Authors: Diouane Youness , Lamsen Noel , Delfino Gesualdo
Published: February 2022

We use scale invariant scattering theory to obtain the exact equations determining the renormalization group fixed points of the two-dimensional CP

N−1 model, for N real. Also due to special degeneracies at N = 2 and 3, the space of solutions for N ⩾ 2 reduces to that of the O(N
2 − 1) model, and accounts for a zero temperature critical point. For N < 2 the space of solutions becomes larger than that of the O(N
2 − 1) model, with the appearance of new branches of fixed points relevant for criticality in gases of intersecting loops.
Optimal Operation Of Distribution Network With Photovoltaic
Authors: Sun Xiaoxin , Ye Hailong , Li Yan , Huangfu Fenyu , Zhao Chenxu
Published: February 2022

As a clean, renewable and abundant new energy, photovoltaic power generation has gradually gained people’s favor after wind power. Affected by weather, light intensity and temperature, the output of photovoltaic power generation has obvious fluctuation and uncertainty, which seriously threatens the safe and stable operation of power system. Therefore, it is of great practical significance to study the optimal operation of distribution network containing photovoltaic. In this paper, the short-term output characteristics of photovoltaic power generation are studied, and the short-term output model of photovoltaic power generation is established by using the probability distribution of “clear sky index”. On this basis, based on the power flow calculation principle of DistFlow, the operation optimization model of distribution network with photovoltaic power plants is established, and the stochastic characteristics of photovoltaic power generation are flexibly handled by the opportunity constraint method. Using this model, the influence of the stochastic characteristics of photovoltaic power generation on the day-ahead dispatching and reserve capacity of distribution network is calculated and analyzed.
Traveling Wave Fault Location Technology in Distribution Network Based on Non-Contact Sensor
Authors: Ye Yong , Zeng Xiangjun , Yu Kun , Liu Feng , Bi Lanxi
Published: February 2022

In view of the fact that traditional traveling wave sensors need to be directly connected with primary high-voltage equipment, the layout is not flexible, construction is inconvenient, and the traditional ferromagnetic coil traveling wave sensors have problems such as low sensitivity and magnetic saturation. The use of magnetoresistance chip to design non-contact traveling wave sensor is proposed. Theoretical analysis of the magnetoresistance chip is carried out, and the tunnel magnetoresistance chip is selected as the non-contact sensor magnetic sensitive element; the non-contact sensor hardware circuit is designed, the sample is trial-produced, and the experimental test is carried out. The experiment shows that the non-contact sensor can detect a traveling wave signal with a bandwidth of 100kHz∼5MHz, which meets the requirements of traveling wave detection for common fault types in the distribution network. A demonstration project has been built, and operation shows that the non-contact sensor can successfully detect single-phase grounding, interphase short circuit, lightning strikes and other fault types traveling wave signal, sensitivity is higher than traditional traveling wave sensor, positioning error is less than 150m.
Rolling Wheel Abrasion Condition Monitoring of Control Rod Drive Mechanism in Nuclear Reactor
Authors: Zhang Liming , Li Qiao , Luo Jingdong , Li Lin , Wang Yiming
Published: February 2022

During the operation of in nuclear reactor, the reliability is largely influenced by the changes of working states of control rod drive mechanism. The abrasion of rolling wheel is one of the most serve faults leading to the control failure. To monitor the rolling wheel in the control rod drive mechanism in nuclear reactor, a new recognition method based on complexity of the singular spectrum entropy has been introduced. In this method, the singular spectrum entropy of vibration signal of the system is firstly calculated. Then an index of brain wave information complexity is used to define the singular spectrum entropy complexity. The complexity index is more sensitive to the uncertainty of the signal and it can effectively reflect the intensity of the random shock signal by abrasion which makes it possible to assess the abrasion condition. Through the control rod drive mechanism of whole life test, it is proved that this method can be used in nuclear reactor control rod drive mechanism rolling wheel abrasion condition monitoring with proper accuracy.
Selection of Electrochemical Energy Storage Types Based on Renewable Energy Storage Technology
Authors: Jiang Minglei
Published: February 2022

With the strong support of the national new energy policy, higher requirements are put forward for the flexible regulation ability base on the power system. It is the key factor of the flexible regulation ability of the system. How to achieve better new energy consumption through reasonable selection of energy storage types has become an urgent problem to be solved. In view of this, this paper establishes an energy storage type selection model and analyzes a numerical example. The conclusion is that lead-carbon battery and lithium-ion battery have different advantages: lead battery is more suitable for small-scale new energy consumption. Although lithium-ion battery is superior to lead-carbon battery in construction, operation and maintenance, it has more cycles, avoids frequent replacement, and has high battery conversion efficiency. With the further decline of battery manufacturing cost, the benefit of investing in energy storage system will be further improved. The conclusion can provide a basis for formulating relevant policies
Research on Energy Harvesting of Piezoelectric Vibration Using 2D ABH Structure
Authors: Chen Bing , Ren Jiang , Ma Kaixuan
Published: February 2022

The acoustic black hole (ABH) effect can achieve energy concentration by changing the structural characteristics and reducing the propagation velocity of curved waves. This way of energy gathering provides a new idea for the harvesting of vibration energy. In this study, an energy collection structure with 2D ABH characteristics is proposed and studied, which can effectively provide energy harvesting efficiency. According to the theory of geometric acoustics, the size of the piezoelectric patch is designed to be smaller than the half wavelength of the bending wave at the centre of ABH, so as to avoid the situation of positive and negative charge cancellation caused by multiple bending waves on a single piezoelectric patch, and improve the energy utilization rate. The electromechanical coupling model of 2D ABH structure and piezoelectric energy collection circuit was established to study the energy harvesting performance of the plate with 2D ABH structure under transient and steady state conditions. The results show that the 2D ABH structure can effectively increase the frequency width range of vibration energy harvesting and improve energy harvesting efficiency
Hysis Simulation Optimization of Distillation Desulfurization for Mixed Light Hydrocarbons in Tahe Oil Field
Authors: He Yuantai , Zhao Deyin
Published: February 2022

In order to improve the performance of distillation desulfurization unit for mixed light hydrocarbons in Tahe Oil Field, HYSIS simulation investigation was performed. The influences of feed temperature, operation pressure, reboiler temperature and plate number on sulfur content of bottom product, flow rate of product, energy consumption and saturated vapor pressure of light hydrocarbons were carefully discussed. It is indicated that the total energy consumption can be reduced by 45.78% if the unit is operated at the optimized conditions. Meanwhile, the sulfur content of the bottom product will be less than 0.05% and the flow rate of bottom product can be increased by 2.04 t/d while the flow rate of top gas product can be decreased up to 754.11 Nm3/d. In addition, the saturated vapor pressure of light hydrocarbons is lower than the operation pressure.
Research on Full Flow Passage Characteristics of Double Screw Pump Based on Immersion Entity Method
Authors: Qiu Rangjia , Zhang Weibin , Jiang Qifeng , Shen Kun , Gread Bois , Yuan Shuai
Published: February 2022

In order to obtain the full flow passage characteristics of the suction chamber and the internal rotor of the double rectangular screw pump, based on the immersed solid method, using the CFD simulation platform, the transient numerical simulation of the typical design conditions of the screw pump with given basic parameters is carried out by using the N-S equation and SST Turbulence Model, and the flow characteristics of the suction chamber of the rectangular screw pump and the flow characteristics of the rotor during operation are obtained. The numerical simulation shows that the pressure fluctuation in the suction chamber is mainly caused by the periodic opening and closing of the closed domain of the volume formed by the double screw rotation, which is mainly the frequency-doubling pulse. The pressure field and the vorticity field analysis show that the uneven of pressure and velocity distribution of internal flow are also mainly caused by the periodic opening and closing of the closed volume formed when the twins-crew is rotated, and the negative pressure and the vortex are mainly generated from the enclosed volume area and spread in the axial direction to the suction inlet and in the radial direction.
Application and Analysis of Air-Source Heat Pump Heat Supply System in Cold Areas
Authors: Ji Shuo , Liu Yang , Xu Huixuan , Yang Yiwei , Chen Jing , Xue Keli , Sun Yong
Published: February 2022

With the establishment of 3060 double carbon target, higher requirements are put forward for clean energy heating of new buildings in China. Among them, air source heat pump has entered the public’s field of vision with its characteristics of cleanness, environmental protection and high operating efficiency. With the development of heat pump technology, air-source heat pump can run stably at -25°C, and Zhangjiakou, which is located in a cold area, can also use air-source heat pump as the heat source of office buildings. At the same time, the economic analysis shows that the building heating cost of air source heat pump heating system is more economical and energy-saving than that of new central heating system.
Research on Power System Material Management Digitalization Technology Based on Process Reengineering
Authors: Yang Ruosong , Wang Jing , Zhang Xiaoyue , Fu Junxiong , Jia Xinyi
Published: February 2022

This paper analyzes the problems existing in the material management system of electric power system, probes into the digital technology of material management business of electric power system, and puts forward the application of business process reengineering concept in material management of electric power system. Study the digital method of material management business, use the business process reengineering technology to study the hidden data advantage of the material management business of the city power grid, realize the data flow to the right person automatically and transmit the right data at the right time, solve the contradiction between global demand and scattered supply of data and information.