Effect of Transport Coefficients on Excitation of Flare-induced Standing Slow-mode Waves in Coronal Loops

Wang, Tongjiang,Ofman, Leon,Sun, Xudong,Solanki, Sami K.,Davila, Joseph M. American Astronomical Society 2018 The Astrophysical journal Vol.860 No.2

<P>Standing slow-mode waves have been recently observed in flaring loops by the Atmospheric Imaging Assembly of the Solar Dynamics Observatory. By means of the coronal seismology technique, transport coefficients in hot (similar to 10 MK) plasma were determined by Wang et al., revealing that thermal conductivity is nearly suppressed and compressive viscosity is enhanced by more than an order of magnitude. In this study, we use 1D nonlinear MHD simulations to validate the predicted results from the linear theory and investigate the standing slow-mode wave excitation mechanism. We first explore the wave trigger based on the magnetic field extrapolation and flare emission features. Using a flow pulse driven at one footpoint, we simulate the wave excitation in two types of loop models: Model 1 with the classical transport coefficients and Model 2 with the seismology-determined transport coefficients. We find that Model 2 can form the standing wave pattern (within about one period) from initial propagating disturbances much faster than Model 1, in better agreement with the observations. Simulations of the harmonic waves and the Fourier decomposition analysis show that the scaling law between damping time (tau) and wave period (P) follows tau proportional to P-2 in Model 2, while tau proportional to P in Model 1. This indicates that the largely enhanced viscosity efficiently increases the dissipation of higher harmonic components, favoring the quick formation of the fundamental standing mode. Our study suggests that observational constraints on the transport coefficients are important in understanding both the wave excitation and damping mechanisms.</P>

Set-membership Estimation for Event-triggered 2-D Systems Based on Zonotopes

Xudong Wang,Guoqi Wang,Liu Yang,Jitao Li 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.3

This article discusses the interval estimation for 2-D systems in Roesser model with amplitude-boundedenvironmental disturbance and measurement noise. To save the limited capacity of communication network, anevent-triggered communication strategy is adopted to reduce the amount of packets transmitted through the network. Considering the amplitude-bounded uncertainties, an observer design criterion with peak-to-peak norm boundis deduced to suppress the influence of uncertainties on estimation error. A zonotope-based interval estimation approach is derived such that the actual state of 2-D Roesser system is enclosed within the estimated intervals on thebasis of the obtained observer. Finally, a numerical example is presented to verify the effectiveness of the proposedalgorithm

On the Capacity Gain from Full Duplex Communications in a Large Scale Wireless Network

Wang, Xudong,Huang, Huaiyu,Hwang, Taewon IEEE Computer Society 2016 IEEE TRANSACTIONS ON MOBILE COMPUTING Vol.15 No.9

<P>Compared to half duplex communications, full duplex communications can significantly improve link capacity. However, in a large scale wireless network such as a wireless mesh network, the capacity gain from full duplex communications has not been fully investigated. To this end, a metric of network capacity called transmission capacity is studied in this paper for a full duplex wireless network. It captures the maximum transmission throughput in a unit area, subject to a certain outage probability. The key challenge of deriving transmission capacity is to characterize the aggregate interference of the typical link in a full duplex wireless network, which is completely different from that in a half duplex wireless network. In this paper, stochastic geometry is employed to model the network topology as a Thomas cluster point process and then the aggregate interference is characterized as a shot-noise process. Based on these models, the transmission capacity is derived. Analytical results show that under the same network density the distribution of aggregate interference in a full duplex wireless network is more dispersed than that in a half duplex wireless network. Comparisons of transmission capacity between a full duplex network and a half duplex network reveal that the capacity gain from full duplex communications is limited due to severe aggregate interference. This result implies that self-interference cancellation alone cannot ensure scalable full duplex wireless networking.</P>

Wind turbine airfoils optimization design by generalized regression neural network under small sample

Xudong Wang,Hao Ju,Jiahong Lu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1

Neural network models can quickly and accurately predict the aerodynamic performance of wind turbine airfoils based on existing data, but the construction of a large number of learning samples requires a high upfront time cost. To address this problem, a generalized regression neural network (GRNN) model of wind turbine airfoils based on a small sample set is established, and an optimal design method for airfoil aerodynamic performance under multiple constraints is proposed. This method is used to improve the prediction accuracy of the model in the optimization process and to solve the problem of insufficient learning caused by poor training data. Based on the established optimal design model, we applied the particle swarm optimization (PSO) algorithm to complete the optimal design of NACA44XX series airfoils and obtained the optimized airfoils with maximum relative thicknesses of 15 %, 18 %, 21 %, and 24 %, respectively. The aerodynamic characteristics of the new airfoils were analyzed in comparison with the baseline airfoils. The results show that the aerodynamic properties of the new airfoils are significantly improved, with the maximum lift coefficient and maximum lift-to-drag ratio increasing by up to 16.93 % and 10.41 %. Moreover, the optimization efficiency of the method is much higher than that of the traditional one. Thus, it was verified that the method is feasible and effective.

In silico identification and computational characterization of endogenous small interfering RNAs from diverse grapevine tissues and stages

Xudong Zhu,Songtao Jiu,Xiaopeng Li,Kekun Zhang,Mengqi Wang,Chen Wang,Jinggui Fang 한국유전학회 2018 Genes & Genomics Vol.40 No.8

Small interfering RNAs (siRNAs) are effectors of regulatory pathways underlying plant development, metabolism, and stress- and nutrient-signaling regulatory networks. The endogenous siRNAs are generally not conserved between plants; consequently, it is necessary and important to identify and characterize siRNAs from various plants. To address the nature and functions of siRNAs, and understand the biological roles of the huge siRNA population in grapevine (Vitis vinifera L.). The high-throughput sequencing technology was used to identify a large set of putative endogenous siRNAs from six grapevine tissues/organs. Subsequently, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was performed to classify the target genes of siRNA. In total, 520,519 candidate siRNAs were identified and their expression profiles exhibited typical temporal characters during grapevine development. In addition, we identified two grapevine trans-acting siRNA (TAS) gene homologs (VvTAS3 and VvTAS4) and the derived trans-acting siRNAs (tasiRNAs) that could target grapevine auxin response factor (ARF) and myeloblastosis (MYB) genes. Furthermore, the GO and KEGG analysis of target genes showed that most of them covered a broad range of functional categories, especially involving in disease-resistance process. The large-scale and completely genome-wide level identification and characterization of grapevine endogenous siRNAs from the diverse tissues by high throughput technology revealed the nature and functions of siRNAs in grapevine.

Experimental Studies on Circular CFST Frames with ALC Walls under Cyclic Loadings

Bo Wang,Jingfeng Wang,Xudong Gong,Bingkang Liu 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.4

To investigate the interaction and failure mechanism between aerated lightweight concrete (ALC) walls and concrete-filledsteel tubular (CFST) frames under seismic action, one specimen of circular CFST frame and four specimens of circular CFSTframes with ALC walls under cyclic loading were carried out. The test parameters included the panel thickness, the wallconnector type and the panel type. Test process and failure modes of the typed structures were investigated in detail. Hystereticcurves, ductility and energy dissipation etc were also analyzed. The test result showed that using reasonable measurement ofU-typed connector, hooked bolt, rocking connector and angle steel, circular CFST frames and ALC walls under seismicloadings can be in cooperative work and have good seismic performance.

Proteasome subunit beta type 1 interacts directly with Rheb and regulates the cell cycle in Cashmere goat fetal fibroblasts

Yanfeng Wang,Xudong Guo,Zhigang Wang,Zhixin Guo,Mingtao Liu,Keyu Zhao,Xue Feng,Xu Zheng,Xiaojing Wang,Huifang Hao 한국통합생물학회 2017 Animal cells and systems Vol.21 No.5

PSMB1 (proteasome subunit beta type 1) is a core component of the 20S proteasome, and based on its structure, it might have a crucial function in the transcription of certain genes. Rheb (Ras homolog enriched in brain) is a Ras-like small GTPase that acts as an upstream positive regulator of the mechanistic target of rapamycin complex 1 (mTORC1) pathway. We cloned and characterized PSMB1 (KY310590.1) to determine its function in cell cycle progression and proliferation of goat fetal fibroblasts (GFbs). Further, by yeast two-hybrid screen and coimmunoprecipitation, we conformed that PSMB1 interacts directly with Rheb. An siRNA was designed and expressed targeting PSMB1 mRNA in GFbs and inducing cell cycle arrest. Rheb overexpression in GFbs significantly increased the number of S phase cells and growth efficiency compared with control cells. These data indicate that PSMB1 and Rheb have important functions in the cell cycle and proliferation of GFbs, indicating that their interaction governs many processes in GFbs.

Relationship among porcine lncRNA TCONS_00010987, miR-323, and leptin receptor based on dual luciferase reporter gene assays and expression patterns

Ding, Yueyun,Qian, Li,Wang, Li,Wu, Chaodong,Li, DengTao,Zhang, Xiaodong,Yin, Zongjun,Wang, Yuanlang,Zhang, Wei,Wu, Xudong,Ding, Jian,Yang, Min,Zhang, Liang,Shang, Jinnan,Wang, Chonglong,Gao, Yafei Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.2

Objective: Considering the physiological and clinical importance of leptin receptor (LEPR) in regulating obesity and the fact that porcine LEPR expression is not known to be controlled by lncRNAs and miRNAs, we aim to characterize this gene as a potential target of SSC-miR-323 and the lncRNA TCONS_00010987. Methods: Bioinformatics analyses revealed that lncRNA TCONS_00010987 and LEPR have SSC-miR-323-binding sites and that LEPR might be a target of lncRNA TCONS_00010987 based on cis prediction. Wild-type and mutant TCONS_00010987-target sequence fragments and wild-type and mutant LEPR 3'-UTR fragments were generated and cloned into pmiRRB-REPORT^TM-Control vectors to construct respective recombinant plasmids. HEK293T cells were co-transfected with the SSC-miR-323 mimics or a negative control with constructs harboring the corresponding binding sites and relative luciferase activities were determined. Tissue expression patterns of lncRNA TCONS_00010987, SSC-miR-323, and LEPR in Anqing six-end-white (AQ, the obese breed) and Large White (LW, the lean breed) pigs were detected by real-time quantitative polymerase chain reaction; backfat expression of LEPR protein was detected by western blotting. Results: Target gene fragments were successfully cloned, and the four recombinant vectors were constructed. Compared to the negative control, SSC-miR-323 mimics significantly inhibited luciferase activity from the wild-type TCONS_00010987-target sequence and wild-type LEPR-3'-UTR (p<0.01 for both) but not from the mutant TCONS_00010987-target sequence and mutant LEPR-3'-UTR (p>0.05 for both). Backfat expression levels of TCONS_00010987 and LEPR in AQ pigs were significantly higher than those in LW pigs (p<0.01), whereas levels of SSC-miR-323 in AQ pigs were significantly lower than those in LW pigs (p<0.05). LEPR protein levels in the backfat tissues of AQ pigs were markedly higher than those in LW pigs (p<0.01). Conclusion: LEPR is a potential target of SSC-miR-323, and TCONS_00010987 might act as a sponge for SSC-miR-323 to regulate LEPR expression.

A numerical and theoretical investigation on composite pipe-in-pipe structure under impact

Xudong Qian,Yu Wang,J.Y. Richard Liew,Min-Hong Zhang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.5

This paper investigates the transverse impact response for ultra lightweight cement composite (ULCC) filled pipe-in-pipe structures through a parametric study using both a validated finite element procedure and a validated theoretical model. The parametric study explores the effect of the impact loading conditions (including the impact velocity and the indenter shape), the geometric properties (including the pipe length and the dimensions of the three material layers) as well as the material properties (including the material properties of the steel pipes and the filler materials) on the impact response of the pipe-in-pipe composite structures. The global impact responses predicted by the FE procedure and by the theoretical model agree with each other closely. The parametric study using the theoretical approach indicates the close relationships among the global impact responses (including the maximum impact force and the maximum global displacement) in specimens with the equivalent thicknesses, proposed in the theoretical model, for the pipe-in-pipe composite structures. In the pipe-in-pipe composite structure, the inner steel pipe, together with the outer steel pipe, imposes a strong confinement on the infilled cement composite and enhances significantly the composite action, leading to improved impact resistance, small global and local deformations.

Percutaneous endoscopic gastrostomy

Xudong Liu,Zhengqiang Yang,Shun He,Guiqi Wang 소화기인터벤션의학회 2021 International journal of gastrointestinal interven Vol.10 No.2

Percutaneous endoscopic gastrostomy (PEG) is a feasible and safe technique for patients who need long-term feeding and cannot eat orally. With the increasing maturity of PEG technique, a large number of patients receive PEG tube placement every year in the world. However, PEG tube placement is not necessary in some patients, and some other patients are not evaluated strictly, leading to serious complications. In a broad sense, the mainly two indications for PEG include long-term enteral nutrition and gastric decompression. On the other hand, the main contraindications of PEG are distal intestinal obstruction, severe coagulation abnormalities, and severe infection at the PEG site. In the first section of this review, the indications and contraindications of PEG are introduced. Although PEG tube placement is a relatively safe technique, it can still cause a number of complications, including minor and major complications. Through standard management and treatment, the outcome of most patients is very good. In the second section of this review, we describe a variety of minor and major tube-related complications, and the treatment and prevention of these complications. In addition, the preparation and post-insertion care are also very important for PEG, which can reduce the incidence of complications. In the last section of this review, we describe related issues about the preparation and post-insertion care of PEG. In conclusion, PEG tube placement is a widely accepted technique that can bring benefits to the right patients.