Constellation Multi-Objective Optimization Design Based on QoS and Network Stability in LEO Satellite Broadband Networks

( Dawei Yan ),( Peng You ),( Cong Liu ),( Shaowei Yong ),( Dongfang Guan ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.3

Low earth orbit (LEO) satellite broadband network is a crucial part of the space information network. LEO satellite constellation design is a top-level design, which plays a decisive role in the overall performance of the LEO satellite network. However, the existing works on constellation design mainly focus on the coverage criterion and rarely take network performance into the design process. In this article, we develop a unified framework for constellation optimization design in LEO satellite broadband networks. Several design criteria including network performance and coverage capability are combined into the design process. Firstly, the quality of service (QoS) metrics is presented to evaluate the performance of the LEO satellite broadband network. Also, we propose a network stability model for the rapid change of the satellite network topology. Besides, a mathematical model of constellation optimization design is formulated by considering the network cost-efficiency and stability. Then, an optimization algorithm based on non-dominated sorting genetic algorithm-Ⅱ (NSGA-Ⅱ) is provided for the problem of constellation design. Finally, the proposed method is further evaluated through numerical simulations. Simulation results validate the proposed method and show that it is an efficient and effective approach for solving the problem of constellation design in LEO satellite broadband networks.

Construction of E-Commerce Entrepreneurship Curriculum System for College Students: An Information Entrepreneurship Perspective

Yan Hou,Dawei Liu,Shuling Yang 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.11

With the rapid development of Electronic Commerce, the demand for the quantity and professional knowledge of the professional talents in electronic commerce is continuously improving. The development of network market provides an opportunity for college students to start their own business, and the ultimate goal of e-commerce business entrepreneurship is to cultivate students' ability to use e-commerce to start a business. In this paper, the authors analyze the construction of e-commerce entrepreneurship curriculum system for college students based on information technology perspective. In the curriculum system construction, the course is divided into three levels; the first level is mainly about the basic knowledge of e-business, second level is mainly about business development course, and the third levels of curriculum mainly about laws and regulations. Establish and perfect the innovation and entrepreneurship curriculum system, and cultivate the students' awareness of online entrepreneurship is a development trend in the future.

Antioxidant capacity, flavor and physicochemical properties of FH06 functional beverage fermented by lactic acid bacteria: a promising method to improve antioxidant activity and flavor of plant functional beverage

Yan Xian-Tao,Zhang Ziqi,Wang Yubao,Zhang Wenmiao,Zhang Longfei,Liu Yang,Chen Dawei,Wang Wenqiong,Ma Wenlong,Qian Jian-Ya,Gu Ruixia 한국응용생명화학회 2023 Applied Biological Chemistry (Appl Biol Chem) Vol.66 No.-

The ability of natural plants to treat chronic diseases is closely related to their antioxidant function. Lactic acid bacteria (LAB) fermentation is an effective way to improve the nutritional value, biological activity and flavor of food. This study investigated the pH, titratable acidity, total polysaccharide, total flavone, total saponin, total polyphenol, and antioxidant activity of the FH06 beverage before and after probiotic fermentation. Results: After fermentation, FH06 had lower contents of total polysaccharides, total flavonoids, total saponins and total polyphenols but higher titratable acidity. The antioxidant activity was tested by total antioxidant capacity (FRAP method) and DPPH· scavenging ability. The FRAP value significantly increased after fermentation (P < 0.05), and the maximum increase was observed for Lactobacillus fermentum grx08 at 25.87%. For DPPH· scavenging ability, the value of all fermentations decreased, and L. fermentum grx08 had the smallest reduction at 2.21% (P < 0.05). The results of GC–MS and sensory analysis showed that fermentation eliminated bad flavors, such as grass, cassia and bitterness, and highlighted the fruit aroma and soft sour taste. Conclusion: The FRAP value and sensory flavor of FH06 fermentation by L. fermentum grx08 were significantly improved, indicating its great potential as a functional food with both strong antioxidant activity and good flavor.

Performance Evaluation and Analysis of Multiple Scenarios of Big Data Stream Computing on Storm Platform

( Dawei Sun ),( Hongbin Yan ),( Shang Gao ),( Zhangbing Zhou ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.7

In big data era, fresh data grows rapidly every day. More than 30,000 gigabytes of data are created every second and the rate is accelerating. Many organizations rely heavily on real time streaming, while big data stream computing helps them spot opportunities and risks from real time big data. Storm, one of the most common online stream computing platforms, has been used for big data stream computing, with response time ranging from milliseconds to sub-seconds. The performance of Storm plays a crucial role in different application scenarios, however, few studies were conducted to evaluate the performance of Storm. In this paper, we investigate the performance of Storm under different application scenarios. Our experimental results show that throughput and latency of Storm are greatly affected by the number of instances of each vertex in task topology, and the number of available resources in data center. The fault-tolerant mechanism of Storm works well in most big data stream computing environments. As a result, it is suggested that a dynamic topology, an elastic scheduling framework, and a memory based fault-tolerant mechanism are necessary for providing high throughput and low latency services on Storm platform.

A Continuous Regional Current-Voltage Model for Short-channel Double-gate MOSFETs

Zhu Zhaomin,Yan Dawei,Xu Guoqing,Peng Yong,Gu Xiaofeng 대한전자공학회 2013 Journal of semiconductor technology and science Vol.13 No.3

A continuous, explicit drain-current equation for short-channel double-gate (DG) MOSFETs has been derived based on the explicit surface potential equation. The model is physically derived from Poisson’s equation in each region of operation and adopted in the unified regional approach. The proposed model has been verified with numerical solutions, physically scalable with channel length and gate/oxide materials as well as oxide/channel thicknesses.

Excessive copper in feed not merely undermines animal health but affects food safety

Zicheng Ma,Yan Li,Zifeng Han,Zhaohu Liu,Hongyu Wang,Fanliang Meng,Sidang Liu,Dawei Chen,Mengda Liu 대한수의학회 2021 Journal of Veterinary Science Vol.22 No.3

Background: Blackened intestines in slaughtered pigs have been commonly observed in China in recent years. However, no cause has been reported. Objectives: We attempted to determine whether the blackening of the pig intestine was related to an excess of copper (Cu) in their feed. Methods: In this study, we observed and collected porcine intestines in small- and large-scale pig slaughterhouses in Shandong province from May to October 2018. Twelve types of metal ions were detected in the black intestinal samples. Results: The Cu level in the intestine samples was mostly higher than the Chinese national limit for food. Further study showed that Cu supplementation in most commercial porcine feed also exceeded the national standard. An animal model (mouse) that could mimic the intestinal blackening in pigs was established. Compared to control mice, Cu accumulated in the liver and intestines of mice fed an excessive Cu level, confirming the excessive Cu in the feed may be considered the major cause of blackened porcine intestines. Microscopic examination revealed that black intestines had many particles containing Cu in the lamina propria of the intestinal mucosa, and the intestinal mucosal epithelial cells showed degeneration and necrosis. Conclusions: In conclusion, overuse of Cu in animal feed can lead to animal poisoning and Cu accumulation in animal products. Such overuse not only harms the health of livestock but can also affect public health.

Optimization Research of Effective Stimulation for Carbonate Reservoir and its Application

Anle He,Dawei Zhu,Chong Liang,Hewen Zhang,Jun Yan,Jianjun Xu 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.3

Based on the characteristics of carbonate reservoirs, staged-fracturing technology for horizontal wells was adopted to effectively drain the reservior. Fracture parameters including orientation, number, length, fracture conductivity and distribution were optimized, and accordingly a hydraulic fracturing design was developed. Applied in oilfield, this method was proved to be effective in oil production. Therefore, it can provide theoretical guidance for the design of the stage-fractured horizontal wells.

Matrix Channel Width Evolution of Single Crystal Superalloy Under Creep and Thermal Mechanical Fatigue: Experimental and Modeling Investigations

Zixu Guo,Ziyuan Song,Dawei Huang,Xiaojun Yan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

In this study, in the respect of rafting behavior of Ni-based single crystal (SC) superalloy under creep and thermal mechanicalfatigue (TMF), an image processing program is developed to investigate the probability characteristic of γ channel width, anda channel width evolution model considering non-quasi-static modification is proposed. Firstly, the fractured and interruptedtests are conducted on SC superalloy. The channel width evolution behavior under different load conditions is observed viascanning electron microscope. Then, an image processing program based on image binarization is developed to conductstatistics on channel width. The statistical results show that the stress and temperature have significant effects on raftingrate, while the phase difference has a small effect. Meanwhile, the channel width obeys lognormal distribution, and the meanvalues follow linear relationship with standard deviations. In the modeling part, a static model is established to predict themean value evolution of channel width under creep condition. To be generalized to TMF condition, the model is modifiedby considering the non-quasi-static effect. After that, the channel width evolution model is further derived to describe theprobability density distribution of channel width. The predicted channel width evolutions are in good agreement with theexperimental results. The statistical results and models can provide the basis for multiscale modeling of SC superalloy.

Facile Self-Assembly of Fe3O4 Nanoparticles@WS2 Nanosheets: A Promising Candidate for Supercapacitor Electrode

Yu Dai,Xiao Wu,Dawei Sha,Ming Chen,Han Zou,Jie Ren,Jingjing Wang,Xuehua Yan 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.6

Graphene-like dichalcogenides with huge surface area and nanostructuredtransition metal oxides with extraordinarily high theoretical capacities could becomposited as promising electrode candidates for supercapacitors. In this work,monolayer and few-layers WS2 nanosheets were exfoliated by combination ofball-milling and sonication. A facile strategy for the hierarchical self-assembly ofFe3O4 nanoparticles (Fe3O4NPs) on WS2 nanosheets was developed to synthesizeFe3O4NPs@WS2 nanocomposites via hydrothermal method. Fe3O4NPs areuniformly dispersed on the WS2 nanosheets without aggregation. The particlesize of Fe3O4NPs is about 3 nm. The nanocomposite shows strong enhancementsof electrochemical behaviors. This self-assembly synthesis strategy may havegreat prospects for other 0D/2D nanocomposites in supercapacitors and otherenergy devices.

Evolution Behavior of M23C6 Carbides Under Different Hot Deformation Conditions in Alloy 602 CA

Xiaoyu Qin,Xiaojun Yan,Dawei Huang,Xiaoyong Zhang,Mingjing Qi,Stephen Yue 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.6

Alloy 602 CA is a M23C6carbides strengthened Nickel-based superalloy. In this alloy, M23C6is different from that found inother superalloys because of its high volume fraction, wide size distribution and distinct precipitation locations. To investigateM23C6evolution behaviors during hot deformation in Alloy 602 CA, a series of tests are carried out in this study. Thetest temperature ranges from 900 to 1100 °C and strain rate ranges from 0.001 to 0.1 s−1, with a true strain of 0.7. It is foundthat hot deformation of the material decreases the distance between carbides which leads merging happening to changethe morphology of primary M23C6. Secondary carbides mainly come from the dissolution of large primary carbides andprecipitate along grain boundaries and twin boundaries which impede dynamic recrystallization (DRX) from happening. Volume fractions of M23C6decrease from 900 to 1100 °C. At 900 °C and 1100 °C, the precipitation equilibrium is reachedin the preheating period before hot deformation and deformation only change the size distribution of carbides. 1000 °C isa transition temperature where the volume fraction decreases as strain rate increases. The temperature rise initiated by adiabaticheating has a great influence on this precipitation behavior.