bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of the Interactions Between Stream and Groundwater by Permafrost and Seasonal Frost in an Alpine Catchment, Northeastern Tibet Plateau, China
Authors: Ma Rui , Sun Ziyong , Chang Qixin , Ge Mengyan , Pan Zhao
Published: February 2021

While the individual effects of permafrost and seasonal frost on the interactions between groundwater and surface water have received much attention, few attempts have been made to investigate the effects of permafrost and seasonal frost together on groundwater flow and its interactions with surface water. In this study, hydraulic, chemical, and isotopic data as well as a Bayesian mixing model were employed to investigate the interactions between streams and groundwater, the contributions of groundwater to the mainstream, and their relationships to the distribution of permafrost and seasonal frost in a representative subcatchment in the headwater region of the Heihe River Basin on the northeastern Qinghai‐Tibet Plateau in China. Our results showed that due to the freezing and thawing of recharge water sources and soils, the groundwater flow and stream flux from the permafrost zone to the seasonal frost zone increased during the thawing period, with maximum values in thawed period, and decreased during the frozen period. These variations affected groundwater recharge in the seasonal frost zone, resulting in dynamic changes in the groundwater table and the hydraulic gradient between the recharge and discharge points in the seasonal frost zone during the different freeze‐thaw periods. Correspondingly, the contribution of groundwater to the mainstream discharge decreased from 95% during the frozen period to 80%–90% during the thawing period. It then decreased to ∼40%–60% of the mainstream discharge during the thawed period and increased to ∼70%–90% during the refreezing period. From the permafrost zone to the seasonal frost zone and the catchment outlet, the aquifers in the piedmont plain of the seasonal frost zone play an important role in maintaining streamflows by switching their hydrological functions, that is, slowly releasing groundwater to maintain the streamflow during the frozen period and rapidly transferring the groundwater to mainstream during the thawed period.
High‐Resolution Observations of Turbulence Distributions Across Tropopause Folds
Authors: Söder Jens , Zülicke Christoph , Gerding Michael , Lübken Franz‐Josef
Published: February 2021

In this study, we interpret two vertical turbulence measurements. We acquired these uninterrupted high‐resolution dissipation rate profiles with the balloon‐borne instrument LITOS (Leibniz Institute Turbulence Observations in the Stratosphere) from velocity measurements using a spectral technique. The meteorological situation is characterized using ECMWF’s integrated forecast system (IFS) as breaking Rossby waves showing significant tropospheric jets and a developed tropopause fold. In both cases, dissipation rates in the shear zone above the upper‐tropospheric jet are three orders of magnitude larger than below, reaching severe turbulence strengths (1,000 mW kg−1) in a deep tropopause fold and moderate turbulence strengths in a medium tropopause fold (10 mW kg−1). These turbulent spots are shown to create a tripole shaped pattern of PV modification across the tropopause. Furthermore, tracer‐tracer correlations exhibit mixing of tropospheric and stratospheric air masses in the medium‐fold case. While the strength of turbulence corresponds to the depth of the tropopause fold, its asymmetric vertical distribution is possibly related to the tropopause fold life cycle. The observed asymmetry in the vertical turbulence distribution is consistent across both tropopause folds and in overall agreement with measured Richardson numbers. In the medium‐fold case however, it is neither expected from conceptual models nor from Richardson numbers in the IFS. This calls for further field campaigns to investigate the role of turbulence and its implications for the meteorological understanding as well as for aviation safety.
Observational Validation of Parameterized Gravity Waves From Tropical Convection in the Whole Atmosphere Community Climate Model
Authors: Alexander M. J. , Liu C. C. , Bacmeister J. , Bramberger M. , Hertzog A. , Richter J. H.
Published: February 2021

Tropical gravity waves that are generated by convection are generally too small in scale and too high in frequency to be resolved in global climate models, yet their drag forces drive the important global‐scale quasi‐biennial oscillation (QBO) in the lower stratosphere, and models rely on parameterizations of gravity wave drag to simulate the QBO. We compare detailed properties of tropical parameterized gravity waves in the Whole Atmosphere Community Climate Model version 6 (WACCM6) with gravity waves observed by long‐duration superpressure balloons and also compare properties of parameterized convective latent heating with satellite data. Similarities and differences suggest that the WACCM6 parameterizations are excellent tools for representing tropical gravity waves, but the results also suggest detailed changes to the gravity wave parameterization tuning parameter assumptions that would bring the parameterized waves into much better agreement with observations. While WACCM6 currently includes only nonstationary gravity waves from convection, adding gravity waves generated by the steady component of the heating that are stationary relative to moving convective rain cells is likely to improve the simulation of the QBO in the model. The suggested changes have the potential to alleviate common biases in simulated QBO circulations in models.
Icefield Breezes: Mesoscale Diurnal Circulation in the Atmospheric Boundary Layer Over an Outlet of the Columbia Icefield, Canadian Rockies
Authors: Conway J. P. , Helgason W. D. , Pomeroy J. W. , Sicart J. E.
Published: February 2021

Atmospheric boundary layer (ABL) dynamics over glaciers mediate the response of glacier mass balance to large‐scale climate forcing. Despite this, very few ABL observations are available over mountain glaciers in complex terrain. An intensive field campaign was conducted in June 2015 at the Athabasca Glacier outlet of Columbia Icefield in the Canadian Rockies. Observations of wind and temperature profiles with novel kite and radio‐acoustic sounding systems showed a well‐defined mesoscale circulation developed between the glacier and snow‐free valley in fair weather. The typical vertical ABL structure above the glacier differed from that expected for “glacier winds”; strong daytime down‐glacier winds extended through the lowest 200 m with no up‐valley return flow aloft. This structure suggests external forcing at mesoscale scales or greater and is provisionally termed an “icefield breeze.” A wind speed maximum near the surface, characteristic of a “glacier wind,” was only observed during night‐time and one afternoon. Lapse rates of air temperature down the glacier centerline show the interaction of down‐glacier cooling driven by sensible heat loss into the ice, entrainment and periodic disruption and warming. Down‐glacier cooling was weaker in “icefield breeze” conditions, while in “glacier wind” conditions, stronger down‐glacier cooling enabled large increases in near‐surface temperature on the lower glacier during periods of surface boundary layer (SBL) disruption. These results raise several questions, including the impact of Columbia Icefield on the ABL and melt of Athabasca Glacier. Future work should use these observations as a testbed for modeling spatio‐temporal variations in the ABL and SBL within complex glaciated terrain.
Podcast: A Modern Way to Look for Aliens
Authors: Cartier Kimberly
Published: February 2021

The search for extraterrestrial intelligence is undergoing a 21st century transformation. The field is poised to lead the way as an example of interdisciplinary research and inclusive science.
Cyanation of glycine derivatives
Authors: Liang Jia , Fu Ying , Bao Xiazhen , Ou Lanlan , Sang Tongzhi , Yuan Yong , Huo Congde
Published: February 2021

We report a catalytic oxidative C–H cyanation of glycine derivatives using a simple copper(i) catalyst with NFSI as an oxidant via a radical process to furnish α-cyano glycine derivatives.
Valorisation of rejected unripe plantain fruits ofMusaAAB Simmonds: from nutritional characterisation to the conceptual process design for prebiotic production
Authors: Gómez James A. , Pino-Hernández Enrique , Abrunhosa Luís , Matallana Luis G. , Sánchez Óscar J. , Teixeira José A. , Nobre Clarisse
Published: February 2021

Analysis of the physicochemical composition and thermal properties of the flour derived from unripe Dominico-Hartón plantain pulp for design of a process for the production of IMO syrup.
Enantioseparation and determination of orphenadrine in rat plasma and its application to a stereoselective pharmacokinetic study
Authors: Liu Yanru , Ding Yushan , Song Yongbo , Guo Xingjie
Published: February 2021

Chiral separation and stereoselective pharmacokinetics study of orphenadrine enantiomers in rats by HPLC-MS/MS.
Metal alkoxide-derived Co@NC/NCNS as a highly efficient bifunctional oxygen electrocatalyst
Authors: Wang Ying , Yuan Hongjie , Liu Fan , Hu Tianjun
Published: February 2021

An efficient bifunctional electrocatalyst integrating Co@NC units and porous structure N-doped carbon nanosheets was synthesized by pyrolysis of Co-glycerates and a subsequent acid etching process. It exhibits remarkable ORR/OER performance.
A 2-pyridone modified zinc phthalocyanine with three-in-one multiple functions for photodynamic therapy
Authors: Li Yanqing , Wang Chongchong , Zhou Lin , Wei Shaohua
Published: February 2021

A 2-pyridone modified zinc phthalocyanine (denoted ZnPc-PYR) achieves a one stone for three birds outcome in the photodynamic therapy (PDT) treatment of cancer.
Achieving environment-friendly production of CsPbBr3 films for efficient solar cells via precursor engineering
Authors: Cao Xiaobing , Zhang Guoshuai , Jiang Long , Cai Yifan , Wang Yu , He Xin , Zeng Qingguang , Chen Jiangzhao , Jia Yi , Wei Jinquan
Published: February 2021

High quality CsPbBr3 films fabricated from water and IPA using perovskite precursor engineering.
Thermally induced and physically cross-linked hydrogel doped with graphene oxide for controlled release
Authors: Li Peihong , Dai Xueyan , Sui Yanlong , Li Rui , Zhang Chunling
Published: February 2021

Graphene oxide doped oligo(lysine)-modified F127 to prepare a series of FLGO hydrogels, which are thermally induced, mechanically enhanced and injectable, and have drug release properties that can be adjusted by pH.
Robust linear quadratic mean field social control: A direct approach
Authors: Xie Tinghan , Wang Bing-Chang , Huang Jianhui
Published: February 2021

This paper investigates a robust linear quadratic mean field team control problem. The model involves a global uncertainty drift which is common for a large number of weakly-coupled interactive agents. All agents treat the uncertainty as an adversarial agent to obtain a “worst case” disturbance. The direct approach is applied to solve the robust social control problem, where the state weight is allowed to be indefinite. Using variational analysis, we first obtain a set of forward-backward stochastic differential equations (FBSDEs) and the centralized controls which contain the population state average. Then the decentralized feedback-type controls are designed by mean field heuristics. Finally, the relevant asymptotically social optimality is further proved under proper conditions.
Main Group Supramolecular Chemistry Led to Surprising New Directions in the Self-Assembly of Organic Macrocycles, Cages, and Cyclophanes
Authors: Johnson Darren W. , Shear Trevor A.
Published: February 2021

Cyclophanes are an admirable class of macrocyclic and cage compounds that often display unusual properties due to their high strain and unusual conformations. However, the exploration of new, complex cyclophanes has been encumbered by syntheses that can be low yielding, require harsh reaction conditions, and arduous purification steps. Herein, we discuss our work using metalloid-directed self-assembly and dynamic covalent chemistry to form cryptands. These were then subjected to mild conditions to produce discrete disulfide, thioether and hydrocarbon macrocycles in high yields. ‘Design of Experiments’ was then used to selectively synthesize targeted macrocycles from complex mixtures.

1 Introduction

2 Cryptands to Cyclophanes

3 Functionalizable Macrocycles

4 ‘Design of Experiments’ Targeted Synthesis

5 Conclusions and Outlook
Transcriptome Profiling Reveals the Endogenous Sponging Role of LINC00659 and UST-AS1 in High-Altitude Induced Thrombosis
Authors: Jha Prabhash Kumar , Vijay Aatira , Prabhakar Amit , Chatterjee Tathagata , Nair Velu , Bajaj Nitin , Kumar Bhuvnesh , Sharma Manish , Ashraf Mohammad Zahid
Published: February 2021

Background The pathophysiology of deep vein thrombosis (DVT) is considered as multifactorial, where thrombus formation is an interplay of genetic and acquired risk factors. Little is known about the expression profile and roles of long noncoding RNAs (lncRNAs) in human subjects developing DVT at high altitude.

Methods Using RNAseQ, we compared peripheral blood mRNA and lncRNA expression profile in human high-altitude DVT (HA-DVT) patients with high-altitude control subjects. We used DESeq to identify differentially expressed (DE) genes. We annotated the lncRNAs using NONCODE 3.0 database. In silico putative lncRNA–miRNA association study unravels the endogenous miRNA sponge associated with our candidate lncRNAs. These findings were validated by small-interfering RNA (siRNA) knockdown assay of the candidate lncRNAs conducted in primary endothelial cells.

Results We identified 1,524 DE mRNAs and 973 DE lncRNAs. Co-expressed protein-coding gene analysis resulted in a list of 722 co-expressed protein-coding genes with a Pearson correlation coefficients >0.7. The functional annotation of co-expressed genes and putative proteins revealed their involvement in the hypoxia, immune response, and coagulation cascade. Through its miRNA response elements to compete for miR-143 and miR-15, lncRNA-LINC00659 and UXT-AS1 regulate the expression of prothrombotic genes. Furthermore, in vitro RNA interference (siRNA) simultaneously suppressed lncRNAs and target gene mRNA level.

Conclusion This transcriptome profile describes novel potential mechanisms of interaction between lncRNAs, the coding genes, miRNAs, and regulatory transcription factors that define the thrombotic signature and may be used in establishing lncRNAs as a biomarker in HA-DVT.
The influence of gas humidity on the discharge properties of a microwave atmospheric-pressure coaxial plasma jet
Authors: Yu Jie , Zhang Wencong , Wu Xiao , Wu Li , Tao Junwu , Huang Kama
Published: February 2021

This paper investigated the influence of gas humidity (1%, 3%, 8%, 10%, and 12%) on the characteristics of a microwave-induced atmospheric plasma jet. The plasma discharge was generated by a microwave solid-state source with a H2O–Ar mixture gas flow of 8.1 L/min. The variation in energy efficiency, O and OH concentrations, rotational temperature of heavy species, shapes of plasma plumes with different humidities, and microwave input powers were recorded and analyzed. The results showed that the concentrations of O and OH increase monotonously with gas humidity at higher input powers while they fluctuate with gas humidity at lower input powers. With an increase in the H2O/Ar ratio from 1% to 12%, the energy efficiency of the plasma generator decreases, and the plasma plumes become shorter and thinner. The rotational temperature of plasma at the nozzle also showed positive correlation with increasing humidity. Adding more input power would make all the values of these parameters increase. This paper is supposed to be helpful for the research of the interaction mechanism of mix gas plasma and microwave power and for improving the effect of plasma treating biomedical materials.
Bubble characteristics and turbulent dissipation rate in horizontal bubbly pipe flow
Authors: Zhao Weiyang , Wang Hang , Bai Ruidi , Wei Wangru , Wang Hongtao
Published: February 2021

The energy dissipation rate is a crucial parameter for system control and turbulence modeling but is difficult to quantify in gas–liquid two-phase flows. Little relevant information is available, especially in horizontal pipe flows. Based on the consideration that the bubble characteristics in a stable bubbly flow are a reflection of flow turbulence, the bubble shape and bubble size spectrum are investigated in a 10-m-long horizontal rectangular pipe by means of high-speed imaging and graphic processing techniques. The bubble size spectra indicate a critical length scale, deemed to be the Hinze scale, and the spectral shape is related to turbulent fragmentation and, thus, enables calculation of the turbulence dissipation rate. After careful validation of the approach for estimating the turbulence dissipation rate, an empirical prediction equation is proposed based on the present tested flow conditions, reflecting the effects of both the pipe flow velocity and the gas flow rate. Such information is useful for the modeling of turbulent two-phase flows.
Energy harvesting from flow-induced vibration of a low-mass square cylinder with different incidence angles
Authors: Han Peng , Huang Qiaogao , Pan Guang , Wang Wei , Zhang Tianqi , Qin Denghui
Published: February 2021

This numerical study investigates the flow-induced vibration responses and energy harvesting characteristics of a low-mass square oscillator. We first test three typical incidence angles of α = 0°, 22.5°, and 45° with reduced velocities Ur ranging from 3.8 to 26. The most interesting phenomenon is that large-amplitude vibrations can be generated at high reduced velocities, regardless of the angle α. We show that this is because of the following mechanisms: (i) For α = 0°, galloping occurs, resulting in high-amplitude and low-frequency vibrations; (ii) for α = 45°, the cylinder undergoes vortex-induced vibrations (VIVs) without the high-amplitude galloping instability. The unsteady vortex shedding effects are enhanced by a very low mass ratio, leading to “VIV forever” in the tested range of Ur with high-level amplitudes; and (iii) for α = 22.5°, the oscillations in the high-Ur range include both VIV and galloping components. Thus, the large amplitude is caused by the galloping instability and enhanced vortex-shedding effects. Due to the existence of large-amplitude vibrations, the low-mass square cylinder demonstrates the potential and necessary robustness for energy harvesting applications. Overall, α = 45° is the most suitable arrangement for the conversion of power. To further improve the efficiency, we test a 45° cylinder under damping ratios ζ ranging from 0.01 to 0.7. The results indicate that the energy harvesting characteristics are sensitive to the damping ratio when ζ < 0.3. Of all the tested cases, ζ = 0.7 provides the highest average efficiency.
Tungsten divertor plasma simulation with bundled charge state model by SOLPS-ITER on EAST
Authors: Gao Shanlu , Liu Xiaoju , Deng Guozhong , Ming Tingfeng , Li Guoqiang , Zhang Xuexi , Tao Yuqiang , Gao Xiang
Published: February 2021

Research was originally carried out to evaluate plasma performance with a tungsten (W) divertor on EAST using the bundled charge state model by the coupled multi-fluid plasma and kinetic neutral code SOLPS-ITER. This work focuses on the comparisons of several bundled charge state models of W and the all W ion model in low and high recycling divertor operational regimes. It is found that bundled charge state models have a pronounced effect on the reduction of computational time and computer memory and provide an improved marked code speed by a factor of more than five. In the low recycling regime, compared to the full W charge state model, the differences in the plasma parameters at both divertor targets are within 15% for different bundling schemes. In the high recycling regime, no significant difference between bundled charge state models and the all charge state model is observed due to the very low W concentration (∼10−6). It, therefore, indicates that bundled charge state models of W can describe divertor parameters well to a considerable degree. Besides, the errors of tungsten concentration (CW) and the effective ion charge number (Zeff) at the outer mid-plane for bundled models are within 40% inside the separatrix. At the same time, highly resolved bundled models with more than 20 W fluids can describe the radiation power loss consistently within 50% as compared with the all charge state model, while it varies greatly from one aggressively bundled model to the other, especially for core radiation, which is strongly related to the bundling schemes for relatively high charge states.
Breakthrough the communication bottleneck between sky and underwater
Authors: Long Jiawei , Xie Shimeng , Li En , Gao Chong , Gao Yong , Zhang Yunpeng , Zheng Hu , Guo Gaofeng , Huang Lin
Published: February 2021

We report on an experimental demonstration of two-way communication between sky and underwater for the first time. Signal transmission from sky to underwater is realized by the thermoacoustic effect (TE), while from underwater to sky, this is based on the microwave vibration measurement (MVM). With a homemade experimental setup, the two-way transmission of “UESTC” is realized. This study suggests that TE combined with MVM has the potential to be used for two-way wireless communication between sky and underwater.
Enhancement of magnetic coupling and magnetic anisotropy in MTJs with multiple CoFeB/MgO interfaces for high thermal stability
Authors: Nishioka K. , Honjo H. , Naganuma H. , Nguyen T. V. A. , Yasuhira M. , Ikeda S. , Endoh T.
Published: February 2021

Magnetic coupling between two CoFeB layers through the W insertion layer is important in the conventional double CoFeB/MgO interface, magnetic tunneling junctions (MTJs) (double-MTJs) with MgO/CoFeB/W/CoFeB/MgO free layer stack because it increases the effective magnetic volume of the free layer. The magnetic coupling energy constant per unit area, Jcpl, between two CoFeB layers through the W layer and the effective perpendicular magnetic anisotropy (PMA) energy constant per unit area, Kefft*, were investigated for conventional double-MTJs with various W insertion layer thicknesses. As the W layer thickness increased, Kefft* increased and Jcpl decreased. There exists a trade-off relationship between Jcpl and Kefft*. In conventional double-MTJs with a single W insertion layer, large values for Jcpl and Kefft* were difficult to obtain simultaneously. To improve this tradeoff, we employed a free layer stack with a thin ferromagnetic layer (ferromagnetic bridge layer: FBL) located in the W insertion layer. In the double-MTJs with FBL annealed at 400 °C, a large Jcpl value of 0.37 mJ/m2 was achieved while maintaining the maximum values of Kefft*. Accordingly, the MTJ with FBL provides an MTJ stack structure for obtaining high thermal stability.
Widespread polycistronic gene expression in green algae
Authors: Gallaher Sean D. , Craig Rory J. , Ganesan Iniyan , Purvine Samuel O. , McCorkle Sean R. , Grimwood Jane , Strenkert Daniela , Davidi Lital , Roth Melissa S. , Jeffers Tim L. , Lipton Mary S. , Niyogi Krishna K. , Schmutz Jeremy , Theg Steven M. , Blaby-Haas Crysten E. , Merchant Sabeeha S.
Published: February 2021

Significance

Historically, it has been understood that for gene expression in eukaryotes, each messenger RNA encodes a single protein. With the recent development of technologies to sequence full-length transcripts en masse, we have discovered hundreds of examples in two species of green algae where two, three, or more proteins are translated from a single transcript. These “polycistronic” transcripts are found in diverse species throughout the green algal lineage, which highlights their biological importance. We have leveraged these findings to coexpress pairs of genes on polycistronic transcripts in vitro, which should facilitate efforts to engineer algae for research and industrial applications.
Semi-infinite travelling waves arising in a general reaction–diffusion Stefan model
Authors: Fadai Nabil T
Published: February 2021

We examine travelling wave solutions of the reaction–diffusion equation,

∂

t

u
=
R

(

u

)

+

∂

x

D

(

u

)

∂

x

u

, with a Stefan-like condition at the edge of the moving front. With only a few assumptions on R(u) and D(u), a variety of new semi-infinite travelling waves arise in this reaction–diffusion Stefan model. While other reaction–diffusion models can admit semi-infinite travelling waves for a unique wavespeed, we show that semi-infinite travelling waves in the reaction–diffusion Stefan model exist over a range of wavespeeds. Furthermore, we determine the necessary conditions on R(u) and D(u) for which semi-infinite travelling waves exist for all wavespeeds. Using asymptotic analysis in various distinguished limits of the wavespeed, we obtain approximate solutions of these travelling waves, agreeing with numerical simulations with high accuracy.
Project ThaiPASS: international outreach blending astronomy and Python
Authors: Keegans James D , Stancliffe Richard J , Bilton Lawrence E , Cashmore Claire R , Gibson Brad K , Kristensen Mikkel Theiss , Lawson Thomas V , Pignatari Marco , Vaezzadeh Iraj , Côté Benoit , Chongchitnan Siri
Published: February 2021

We present our outreach program, the Thailand–UK Python+Astronomy Summer School (ThaiPASS), a collaborative project comprising UK and Thai institutions and assess its impact and possible application to schools in the United Kingdom. Since its inception in 2018, the annual ThaiPASS has trained around 60 Thai high-school students in basic data handling skills using Python in the context of various astronomy topics, using current research from the teaching team. Our impact assessment of the 5 day summer schools shows an overwhelmingly positive response from students in both years, with over 80% of students scoring the activities above average in all activities but one. We use this data to suggest possible future improvements. We also discuss how ThaiPASS may inspire further outreach and engagement activities within the UK and beyond.
Designing an argumentation-based educational digital game to teach the subject of force
Authors: Bağ Hasan , Çalık Muammer
Published: February 2021

The aim of this study is to design an argumentation-based educational digital game to teach the subject of force. Through a design-based research method, each game section includes the argumentation questions that foster students to think about the ‘force’ subject. We pilot studied the game with 12 grade 4 students in a state primary school. After successive three pilot studies, we revised and fixed technical and pedagogical problems. We believe that the argumentation-based digital game has the potential to improve grade 4 students’ argumentation qualities and stimulate their learning interest/motivations.
Bounds of the sum of edge lengths in linear arrangements of trees
Authors: Ferrer-i-Cancho Ramon , Gómez-Rodríguez Carlos , Luis Esteban Juan
Published: February 2021

A fundamental problem in network science is the normalization of the topological or physical distance between vertices, which requires understanding the range of variation of the unnormalized distances. Here we investigate the limits of the variation of the physical distance in linear arrangements of the vertices of trees. In particular, we investigate various problems of the sum of edge lengths in trees of a fixed size: the minimum and the maximum value of the sum for specific trees, the minimum and the maximum in classes of trees (bistar trees and caterpillar trees) and finally the minimum and the maximum for any tree. We establish some foundations for research on optimality scores for spatial networks in one dimension.
Virtual-Vector-Based FCS Model Predictive Current Control with Duty Cycle Optimization for Dual Three-Phase Motors
Authors: He Shuai , Li Yaoheng , Shuai Zhibin , Zhang Ying , Gai Jiangtao , Zhou Guangming
Published: February 2021

This paper presents an improved finite control set model predictive current control (FCS-MPCC) based on virtual vectors with duty cycle control for dual three-phase permanent magnet synchronous motor (DTP PMSM) drives. Virtual vectors synthesized by two basic voltage vectors of the inverter are introduced to suppress the harmonic current by the vector space decomposition (VSD) model. And the virtual vectors with the optimal duty cycle can be obtained by duty cycle control using zero vectors to generate a fixed switching frequency. Moreover, a simple scheme of centrosymmetric switching patterns is presented for the realtime implementation. In this way, the performance of current tracking is improved while the computational burden is reduced. Finally, results of simulation analysis and DSP test for the three different strategies are given to verify the validity of the proposed strategy.
A dynamic sliding mode control method for multi-agent formation
Authors: Liu Jinyu , Li Yonggang , Yang Zhaofeng
Published: February 2021

In this article, we study the formation control problem of multiple agents. In the past studies on sliding mode control, when the state trajectory reaches the sliding mode surface, it is difficult to strictly slide along the sliding mode surface to the equilibrium point, but it travels back and forth on both sides to approach the equilibrium point, resulting in chattering. This is also the main obstacle in the practical application of sliding mode control, and in actual scenarios, the agent has a limited communication distance and perception distance. In order to solve this problem, we propose a dynamic sliding mode control method. First, we establish an agent motion model to determine the leader and follower. The trajectory of the formation is deter-mined by the leader, and the follower agent maintains an ideal position in the leader coordinate system. Then, multiple agents conduct formation movement under the guidance of the leader. In this paper, two examples are used for simulation, and the simulation results show the effectiveness of the pro-posed formation control method.
Design of the extruder drive motor and its HNTSM speed control with disturbance observer
Authors: Zhang Jiacheng , Fan Yuanxun , Lu Pengcheng , Cao Dawei , Liu Zhikang
Published: February 2021

In order to meet the requirements of 25kW rated power and 1500r/min rated speed required by the extrusion process of polyester fiber composite materials, a PMSM suitable for this working condition was designed to complete the driving task of the extruder. The geometric model of the motor was established using RMxprt, and the load operation state of the motor was simulated by Maxwell. The motor speed was controlled by a HNTSM control scheme with a disturbance observer, and based on Twin builder and simulink coupled simulation. The simulation results show that the motor can reach the required rated power and rated speed. HNTSM control with disturbance observer is more robust than HNTSM and PID control, and can suppress the jitter caused by sliding mode control. However, compared with PID control, there is still some jitter.
Research on Fault Diagnosis of Steam Turbine Based on Bayesian Network
Authors: Zhang Dongliang , Wang Liufeng , Hong Qinqin , Zhang Kaiwen
Published: February 2021

In the fault diagnosis of steam turbine, multiple faults contain number of uncertainties due to the complexity of fault diagnosis knowledge and the strong correlation and coupling between different faults and massive prior knowledge is needed. In this paper, a fault diagnosis method of steam turbine based on Bayesian network is proposed. Various faults and symptoms are parameterized using Bayesian network nodes. Then rough set theory is used to simplify the complex causal relationship between faults and symptoms, and Noisy-Or model is used to simplify the conditional probability parameters. A diagnostic model of the steam turbine was developed using a simplified Bayesian network. The experiment results are shown to validate the practicality and effectiveness of the proposed designs.
Bearing roller smearing testing machine and its simulation analysis
Authors: Hu Junming , Wang Wen , Hao Xiaopeng
Published: February 2021

Rolling bearings are the most common rotating mechanical parts in actual work, with the rapid development of industrial technology, the performance requirements of rolling bearings in actual work are getting widely used, but under the actual working conditions, some large bearings with low speed and heavy load are easy to be smeared and lead to the extension of bearing life. In order to study the effect of early surface smearing on the fatigue life of rolling bearings, a self-designed bearing roller early smearing tester was designed, the test machine can simulate the movement process of roller in the bearing and make different degree of smearing on the surface of roller. According to the function, the smearing testing machine is divided into four parts: driving system, loading system, signal acquisition system and test system. The smearing testing machine can set the test conditions according to relevant theories to fabricate different degree of early smearing on the bearing roller surface, the transient dynamics simulation can simulate the smearing test of the testing machine, by comparing the results of the simulation analysis with the actual experimental circumstances, the stability and reliability of the testing machine can be proved, and it can also be testified that the test results of the testing machine are researchable.
Linear Superposition Compensation Strategy to Optimize Transient Response for Critical Conduction Mode Boost Converter
Authors: Lyu Dian , li Qidong , Zhang Desheng , Li Linkai , Min Run , Tong Qiaoling
Published: February 2021

For boost converter operating in the Critical Conduction Mode (CRM), linear compensation strategy is widely used to improve the control performance. However, conventional linear compensation is designed for limited input, since transfer functions for different input are often incompatible. In this paper, transient responses with respect to input/reference voltage and load variations are optimized simultaneously by a linear superposition compensation strategy. The objective closed-loop transfer functions for each kind of variations are investigated, which contribute to the overall compensation loop design. According to linear superposition principle, the compensation results are summed as reference current, based on which the switching on/off time is modulated. Although the summed results are convergence, separate compensation loop that includes integral terms can lead to divergence in calculation process. To eliminate the potential divergence, the overall compensation loop is re-designed so as to suit digital implementation. Experimental results show that the linear superposition compensation strategy achieves great transient performance to different kind of variations.
Development and application of substation intelligent inspection robot supporting deep learning accelerating
Authors: Su Lei , Yang Xingang , Cao Boyuan , Wang Yun , Li Xinjia , Lu Wenlian
Published: February 2021

Substation inspection robots usually have low computation capability to run deep learning models. In this paper, a substation intelligent inspection robot that can support real time deep learning models is developed. The Nvidia Jetson TX2 module is the accelerating hardware module of the robot, and TensorRT is the software framework for deep learning model inference accelerating. The robot can satisfy the computational requirement of deep learning based applications, and operate in very low energy consumption. Test results on a fault diagnostic task based on object detection and instance segmentation show that with deep learning accelerating, not only high detection accuracy is achieved, but also inference time is short enough for real time fault diagnostic application.
Low-error star pattern recognition based on point cloud matching algorithm*
Authors: Liang Luo Jing , Bo Yu Cheng , Min Luo
Published: February 2021

Aiming at the problem that the matching rate of traditional star map recognition methods is not high enough, this paper proposes a star map recognition method based on the ICP point cloud matching algorithm based on feature point extraction. Feature points are selected through the change of the local normal vector of the point cloud, and then used Common (ICP) algorithm to realize more accurate registration of point clouds. In order to further reduce the error rate of star map matching, an improved ICP algorithm based on feature points is used to accurately register the point cloud. Finally, the matching conditions of several star maps are obtained through MATLAB tool simulation and the matching rate error rate is calculated. Common ICP algorithm The minimum matching error of is 14.224, and the minimum matching error of the improved ICP algorithm based on feature points is 14.0715. Obviously, the star map matching error rate of the ICP algorithm based on feature points is lower, which also verifies the superiority of the improved ICP algorithm.
Research on the Deviation Analysis of Utilization Hours in Wind Power Plants Based on Regulatory Data Fusion and Feature Extraction & Processing Technologies
Authors: Xiao CHENG , Ping LI , Li-shi SUN , Bing WANG , Lin CONG , Yang YU
Published: February 2021

The continuous elevation of wind power consumption pressure has proposed higher requirements for the technical means, which comprehensively support the wind power consumption. The power generation level of a wind power plant is measured through the utilization hours at present, but the factors influencing the utilization hours are scarcely analyzed and quantified. In order to accurately figure out the reasons for the different utilization hours of wind power plants located in the same area, the total power prediction, power plant data, standalone data, resources, etc. were summarized, and the contribution degrees of five dimensions—resources, equipment availability, AGC command balance degree, AGC command following performance, and power generation capacity—to the utilization hours were analyzed and quantified through the data fusion and feature extraction, in an effort to find the main factors influencing the utilization hours in different power plants. The customized measures were proposed according to the conclusions in order to increase the utilization hours for the power plants. The derived computing method was applied to the wind power plant data acquired by a company in a province, followed by the difference analysis of the utilization hours. It was found that in Mulan sectional area, the reason for partially low utilization hours in Jifeng and Xunfeng Wind Power Plants was resource factor, that for Daheishan and Songshan Wind Power Plants lied in equipment availability, and that for Jufeng Wind Power Plant was possibly equipment following performance or equipment power generation capacity. In addition, the AGC command balance degrees in all target power plants were at low levels.
Optimal Number of Cluster Heads for Selection Cooperation in Clustering Wireless Sensor Networks
Authors: Li Min , Gu Huiping , Li Qing
Published: February 2021

In clustering wireless sensor networks, the number of cluster heads has great impact on energy consumption and transmission reliability of the system. With the increase of the number of transmission rounds, the area where the survival nodes are located gradually shrinks. In order to reduce the energy consumption of sensor nodes and improve the network lifetime, this paper proposes a dynamic cluster head (CH) number optimization scheme for selection cooperation. In order to reflect the area where the survival node is located, the network area as a variable is introduced into the energy consumption model. According to the behavioural characteristics of various nodes in the two-stage selection cooperation, the energy consumption model for each round is established. By solving the energy consumption model, the optimal number of cluster head in each round can be obtained. In this way, each round of transmission is carried out according to the minimum energy consumption. The simulation results show that the proposed scheme can reduce the energy consumption of the network, avoid energy waste caused by improper selection of cluster heads and extend the network lifetime.
Two approaches to car sequencing in the paint shop
Authors: Bysko Sara , Krystek Jolanta , Bysko Szymon
Published: February 2021

The problem of car sequencing has been considered in the literature many times, but very often with the assumption of many simplifications, which meant that the discussed issue was far from the problems occurring in reality. The article presents an attempt to capture the real problem of sequencing, in particular in paint shop, because from the point of view of economic indicators, painting process is today a complex, multistage, extremely energy consuming and cost intensive operation. The main goal is therefore to minimize the number of costly changeovers of painting guns, resulting from color changes and synchronize those with periodic cleanings, forced by technological requirements. For this purpose, a buffer located in the paint shop is applied. In the paper a game-theoretic framework is presented to analyze the considered problem. Two games: Buffer Slot Assignment Game and Buffer-OutShuttle are compared with algorithms based on priority rules. Based on the performed simulations the effectivity of presented algorithms is verified using several datasets.
Real-time motion detection in H.264 compressed domain for surveillance application
Authors: Kim Young Keun , Jeon Yeong Gyoo , Shin Seung Ho
Published: February 2021

Camera motion detection is a useful functionality in video surveillance and many other areas, but with its widespread application in many areas, the compaction power has increased and needs to be addressed how to reduce it. So far, there has been a lot of research on pixel domain, but it is hard to operate with real-time and consumes very much computing power. However, since the compressed domain of block-based codec contains useful information for video analysis, this allows accurate video analysis at a low cost. The proposed method shows how to perform a motion detection accurately while significantly reducing the amount of computation compared to the pixel domain by using the DCT coefficients, motion vectors and other features in the compressed domain of the H.264 video. The proposed algorithm is designed for motion detection in video surveillance servers in the form of a cloud. The results of the experiment were shown to support validity.
Divergent responses of permafrost peatlands to recent climate change
Authors: Sim Thomas G , Swindles Graeme T , Morris Paul J , Baird Andy J , Cooper Claire L , Gallego-Sala Angela V , Charman Dan J , Roland Thomas P , Borken Werner , Mullan Donal J , Aquino-López Marco A , Gałka Mariusz
Published: February 2021

Permafrost peatlands are found in high-latitude regions and store globally-important amounts of soil organic carbon. These regions are warming at over twice the global average rate, causing permafrost thaw, and exposing previously inert carbon to decomposition and emission to the atmosphere as greenhouse gases. However, it is unclear how peatland hydrological behaviour, vegetation structure and carbon balance, and the linkages between them, will respond to permafrost thaw in a warming climate. Here we show that permafrost peatlands follow divergent ecohydrological trajectories in response to recent climate change within the same rapidly warming region (northern Sweden). Whether a site becomes wetter or drier depends on local factors and the autogenic response of individual peatlands. We find that bryophyte-dominated vegetation demonstrates resistance, and in some cases resilience, to climatic and hydrological shifts. Drying at four sites is clearly associated with reduced carbon sequestration, while no clear relationship at wetting sites is observed. We highlight the complex dynamics of permafrost peatlands and warn against an overly-simple approach when considering their ecohydrological trajectories and role as C sinks under a warming climate.
Predicting readmission and death after hospital discharge: a comparison of conventional frailty measurement with an electronic health record-based score
Authors: Tew Yong Yong , Chan Juen Hao , Keeling Polly , Shenkin Susan D , MacLullich Alasdair , Mills Nicholas L , Denvir Martin A , Anand Atul
Published: February 2021

Background

frailty measurement may identify patients at risk of decline after hospital discharge, but many measures require specialist review and/or additional testing.

Objective

to compare validated frailty tools with routine electronic health record (EHR) data at hospital discharge, for associations with readmission or death.

Design

observational cohort study.

Setting

hospital ward.

Subjects

consented cardiology inpatients ≥70 years old within 24 hours of discharge.

Methods

patients underwent Fried, Short Physical Performance Battery (SPPB), PRISMA-7 and Clinical Frailty Scale (CFS) assessments. An EHR risk score was derived from the proportion of 31 possible frailty markers present. Electronic follow-up was completed for a primary outcome of 90-day readmission or death. Secondary outcomes were mortality and days alive at home (‘home time’) at 12 months.

Results

in total, 186 patients were included (79 ± 6 years old, 64% males). The primary outcome occurred in 55 (30%) patients. Fried (hazard ratio [HR] 1.47 per standard deviation [SD] increase, 95% confidence interval [CI] 1.18–1.81, P < 0.001), CFS (HR 1.24 per SD increase, 95% CI 1.01–1.51, P = 0.04) and EHR risk scores (HR 1.35 per SD increase, 95% CI 1.02–1.78, P = 0.04) were independently associated with the primary outcome after adjustment for age, sex and co-morbidity, but the SPPB and PRISMA-7 were not. The EHR risk score was independently associated with mortality and home time at 12 months.

Conclusions

frailty measurement at hospital discharge identifies patients at risk of poorer outcomes. An EHR-based risk score appeared equivalent to validated frailty tools and may be automated to screen patients at scale, but this requires further validation.