Delta-shock for the nonhomogeneous pressureless Euler system

Shiwei Li,Jianli Zhao 대한수학회 2024 대한수학회보 Vol.61 No.3

We study the Riemann problem for the pressureless Euler system with the source term depending on the time. By means of the variable substitution, two kinds of Riemann solutions including delta-shock and vacuum are constructed. The generalized Rankine-Hugoniot relation and entropy condition of the delta-shock are clarified. Because of the source term, the Riemann solutions are non-self-similar. Moreover, we propose a time-dependent viscous system to show all of the existence, uniqueness and stability of solutions involving the delta-shock by the vanishing viscosity method.

Study on a New Fault Diagnosis Method Based on Combining Intelligent Technologies

Shiwei Li,Di Zhou 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.6

In allusion to more indeterminate information and higher speed request characteristic in fault diagnosis system, according to the intelligence complementary strategy, a new fault diagnosis(SWPSO-BPN) model based on combining improved particle swarm optimization (PSO) algorithm and Back-propagation(BP) neural network is proposed in this paper. In the SWPSO-BPN method, an improved PSO (SWPSO) algorithm is proposed to optimize the parameters of BP neural network in order to overcome the shortcomings of slow learning speed and being easy to fall into local minimum, and obtain the optimal values of parameter combination in the BP neural network(SWPSO-BPN) model. Then proposed SWPSO-BPN model is applied to diagnose the fault in order to obtain a new fault diagnosis (SWPSO-BPN-FD) method. Finally, the proposed SWPSO-BPN-FD method is used to test the data from bearing data center of CWRU. The experimental results show that the proposed SWPSO-BPN-FD method can accurately and effectively realize high precision fault diagnosis of rolling bearing. And this method takes on strong robustness and generalization ability.

An Improved Centroid Localization algorithm for WSN

Li ShiWei,Ding Mingli,Zhao YongPing 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.6

In wireless sensor networks (WSN) research area, node localization is one of the most important techniques. An improved Centroid localization algorithm is analyzed and an improved Centroid algorithm with selective anchor node localization algorithm (CSA) for WSN will proposed in this paper. The key point of the algorithm is the most discrepant estimation nodes are selected by the nearest reference anchor node around a distance unknown node. The triangle centroid and the polygon centroid are employed to calculate the coordinates of the estimation nodes to improve node locating precision. MATLAB simulation illustrate that the algorithm is valid and feasible.

Multi-time Scale Coordinated Optimization of New Energy High Permeability Power System Considering Flexibility Requirements

Su Shiwei,Tan Donghong,Li Xianghua,Li Xin,Chen Zitong,Lian Ruiqing,Lenz Soronga Blaise Kevine 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

The high proportion of grid-connected intermittent energy such as wind power and photovoltaic makes the demand for power system flexibility increase sharply. In order to improve the overall flexibility of new energy high permeability system and enhance the economy of power system, promote the new energy consumption of system. This paper presents a multi-time scale Coordinated optimization strategy for the new energy high permeability power system considering flexibility requirement (MTSCOSFR). This strategy makes full use of the adjustment ability of source-load-storage flexible resources and analyzes system flexibility requirements at different time scales, creates multi-time scale optimization scheduling models, including typical week operation simulation model, typical day operation simulation model, typical period operation simulation model. Puts the profit of carbon trading and the penalty cost of insufficient flexibility into the optimization goal. Adopts the idea of multi-time coordination and step-by-step optimization to solve the model. This paper sets two cases to discuss MTSCOSFR. The results show that the comprehensive cost of the typical weekly operation simulation is reduced to 2360 × 104$, the penalty cost of insufficient flexibility in the typical day operation simulation is reduced by 67%, the flexibility capacity increased by 500 MW, the regulation capacity increased by 300 MW, the ramp margin increased by 1500 MW/(5 min) −1. The proposed strategy can improve system flexibility and promote new energy consumption on the basis of ensuring system economy.

Effect of High Energy Shot Peening on the Microstructure and Mechanical Property of AZ31B Mg Alloy/HSLA350 Steel Lap Joints

Rui Li,Xinjian Yuan,Ting Li,Miao Hong,Shiwei Tao,Zhuo Chen,Ge Wang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.5

When using high energy shot peening (HESP) technology, the surface layer of the welded joints produced grain breakage and residual compressive stress. When the shot peening strength is the optimal parameter 0.10 MPa, the residual compressive stress reaches a maximum value of 74.02 MPa, dislocation density in welded joints increased significantly and the tensile shear strength of the joint was increased by 18.6% compared to the joint without HESP treatment (205 MPa), and the fracture position of the welded joint was located in the Al alloy base material, these were brought by fi ne grain strengthening and strain strengthening. When the shot peening strength was 0.05 MPa, the strength of the joint was also improved, but the fracture position of the joint was the same as that without HESP treatment, and they were all in the fusion zone. However, when the shot peening strength was further increased to 0.15 MPa, severe cracks appeared inside the joint, which deteriorates the strength of the Mg/steel joint.

Microstructure and Mechanical Characteristics of Dissimilar TIG Welded 9% Cr Heat-Resistant Steels Joints

Ting Li,Xinjian Yuan,Rui Li,Jiankun Xiong,Shiwei Tao,Kanglong Wu 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.6

Dissimilar 9% Cr heat-resistant steels (G115 and CB2) with good creep properties for ultra-supercritical steam turbines were butt-joined by tungsten inert gas welding. The microstructure of welded metal (WM) was quenched martensite without carbide precipitates and lath packets existed inside prior austenite grains (PAGs), which leaded to higher hardness of WM. Partially melted zone at G115 side was composed of untempered martensite within equiaxed PAGs. The lowest hardness occurred in both G115 and CB2 steels which was attributed to tempered martensite with many M 23 C 6 precipitates. The heat-affected zone consisted of three sub-grains and their microstructure was detailly analyzed in current work. As current increased from 130 to 150 A, both the tensile strength at room temperature and 650°C increased while strength had no obvious change with further increasing current. The values of 673 MPa and 309 MPa corresponded to the tensile stress with 150 A at room temperature and 650°C, respectively. The fracture mode of joints at room temperature was cleavage and ductile failure at 130 and 150 A, respectively. The high-temperature fracture surface at 150 A was composed of deep and fi ne dimples.

TCP-PPCC: Online-Learning Proximal Policy for Congestion Control

Shiwei Wang,Jing Li,Yuyao Guan,Pengpeng Ding 한국통신학회 2020 한국통신학회 APNOMS Vol.2020 No.09

Effective network congestion control strategies are the key to secure the normal operation of complex and changeable networks. The fundamental assumptions of many existing TCP congestion control variants dominated by hand-crafted heuristic algorithms are no longer valid. We propose an algorithm called TCP-Proximal Policy Congestion Control (TCP-PPCC), which is based on deep reinforcement learning algorithm Proximal Policy Optimization (PPO). TCP-PPCC updates the policy offline from the features of the preceding network state and feedback from the current network environment and adjusts the congestion window online with the updated policy. The senders with TCP-PPCC can learn about the changes in network bandwidth more accurately and adjust the congestion window in time. We demonstrate the performance of TCP-PPCC by comparing it with the traditional congestion control algorithm NewReno in four network scenarios with the ns-3 simulator. The results show that in scenario 2, TCPPPCC takes 58.75% improvement in average delay and 27.80% improvement in throughput compared with NewReno.

Fucosylated Chondroitin Sulfate From Sea Cucumber Improves Glucose Metabolism and Activates Insulin Signaling in the Liver of Insulin-Resistant Mice

Shiwei Hu,Ying-Ying Tian,Yao-Guang Chang,Zhao-Jie Li,Chang-Hu Xue,Yu-Ming Wang 한국식품영양과학회 2014 Journal of medicinal food Vol.17 No.7

This study investigated the effects of fucosylated chondroitin sulfate (CHS) isolated from sea cucumber on glucose metabolism and insulin signaling in the liver of insulin-resistant C57BL/6 mice fed a high-fat, high-sucrose diet (HFSD). Male C57BL/6J mice were randomly assigned into six groups: control; HFSD; 1mg RSG/kg$body weight (RSG); 80 mg CHS/kg$body weight (CHS); 20 mg CHS + 1mg RSG/kg$body weight (20 CHS + RSG); and 80 mg CHS + 1mg RSG/kg$body weight (80 CHS + RSG). Blood glucose, insulin parameters, glucose metabolism-related enzymes activities and insulin-signaling transducers in the liver were analyzed at 19 weeks. Results showed that CHS significantly decreased body weight gain, adipose tissue weight, and fasting blood glucose and serum insulin levels in insulin-resistant mice. Rosiglitazone (RSG) is an effective thiazolidinedione hypoglycemic agent, and CHS synergistically enhanced the effect of RSG. CHS feeding normalized the activities of hexokinase, pyruvate kinase, glycogen phosphorylase, glucose-6-phosphatase, and increased glycogen reserves in the liver. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that CHS promoted the mRNA expression of insulin receptors (IR), insulin receptor substrate 2 (IRS-2), phosphatidylinositol 3 kinase (PI3K), protein kinase B (PKB), and glycogen synthase (GS) in the liver of insulin resistant mice, and inhibited glycogen synthase kinase-3 (GSK-3b) mRNA expression. The results suggested that CHS treatment improved glucose metabolism by modulating metabolic enzymes and promoting the PI3K/PKB/GSK-3b signaling pathway mediated by insulin at the transcriptional level. These results provided strong justification for the development of CHS as a functional food.

Effect of supplemental blue light intensity on the growth and quality of Chinese kale

Yamin Li,Yinjian Zheng,Houcheng Liu,Yiting Zhang,Yanwei Hao,Shiwei Song,Bingfu Lei 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.1

The infl uence of blue light on the growth and quality of vegetables is controversial, since both positive and negative eff ectshave been observed on diff erent varieties of vegetables and most research has been conducted with a combination of lightspectrums. In this work, we investigated the eff ects of supplemental blue light intensity on growth, nutritional quality, andhealth-promoting compounds of Chinese kale ( Brassica alboglabra Bailey) using only blue (460 nm) light-emitting diodes10 days before harvest in a greenhouse under ambient light conditions. Four blue-light treatments were conducted (0, 50,100, and 150 μmol m −2 s −1 , named T0, T50, T100, and T150, respectively) with 12 h (6:00–18:00) of light treatment perday. The growth of Chinese kale plants was improved by supplemental blue light. The fresh and dry weights of Chinesekale plants were signifi cantly higher under T50 and T100 than those in the other treatments. The content of chlorophyll band total chlorophyll increased signifi cantly under T50, and the content of carotenoids increased signifi cantly under T150. The contents of soluble sugars and free amino acids were signifi cantly increased under the blue light treatments. The nitratecontent decreased with increasing blue light intensity, while the anthocyanin content increased. The contents of vitamin Cin T50 and total phenolic compounds in T150 were signifi cantly higher than in T0. The fl avonoid contents were signifi canthigher in T50 and T150, and signifi cantly lower in T100. Our results show that blue light can infl uence the growth and qualityof Chinese kale and 50 μmol m −2 s −1 of supplemental blue light might be the most feasible light intensity for Chinesekale production.

Responses of Low-Quality Soil Microbial Community Structure and Activities to Application of a Mixed Material of Humic Acid, Biochar, and Super Absorbent Polymer

Fangze Li,Shuhui Men,Shiwei Zhang,Juan Huang,Xuehua Puyang,Zhenqing Wu,Zhanbin Huang 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.9

Low-quality soil for land reuse is a crucial problem in vegetation quality and especially to waste disposal sites in mining areas. It is necessary to find suitable materials to improve the soil quality and especially to increase soil microbial diversity and activity. In this study, pot experiments were conducted to investigate the effect of a mixed material of humic acid, super absorbent polymer and biochar on low-quality soil indexes and the microbial community response. The indexes included soil physicochemical properties and the corresponding plant growth. The results showed that the mixed material could improve chemical properties and physical structure of soil by increasing the bulk density, porosity, macro aggregate, and promote the mineralization of nutrient elements in soil. The best performance was achieved by adding 3 g·kg-1 super absorbent polymer, 3 g·kg-1 humic acid, and 10 g·kg-1 biochar to soil with plant total nitrogen, dry weight and height increased by 85.18%, 266.41% and 74.06%, respectively. Physicochemical properties caused changes in soil microbial diversity. Acidobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Nitrospirae, Planctomycetes, and Proteobacteria were significantly positively correlated with most of the physical, chemical and plant indicators. Actinobacteria and Armatimonadetes were significantly negatively correlated with most measurement factors. Therefore, this study can contribute to improving the understanding of low-quality soil and how it affects soil microbial functions and sustainability.