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Impact of Large-scale Wind Power Integration on the UFLS Scheme
Xue, Feng,Li, Yue,Song, Xiao-Fang,Mo, Ruan-Qing The Korean Institute of Electrical Engineers 2014 The Journal of International Council on Electrical Vol.4 No.3
This paper analyzes some major factors for the impact of wind power integration on power system dynamic frequency characteristics in theory. Combining with an actual grid, test scenarios with various scales of doubly fed induction generator (DFIG)-based wind power integration are formulated. Through simulation in the scenarios with FASTEST software, the impacts on the action of under frequency load shedding (UFLS) scheme are displayed in two aspects, the rate of change of frequency (ROCOF) and wind turbine generator own protection. Simulation result shows that the ROCOF will not affect the lock action of UFLS devices in the test system of this paper. Wind turbine generator protection may worsen frequency responses, so it is proposed to be in harmony with the design of UFLS scheme.
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Conditional Replication of a Recombinant Adenovirus Studied Using Neomycin as a Selective Marker
Xue, Feng,Qi, Yi-Peng,Joshua, Mallam Nock,Lan, Ping,Dong, Chang-Yuan Korean Society for Biochemistry and Molecular Biol 2003 Journal of biochemistry and molecular biology Vol.36 No.3
An E1B-defective adenovirus, named r2/Ad carrying the neo expression cassette, was constructed by homologous recombination. The construction, selection (using neomycin as a selective marker), and propagation of the recombinant virus was performed in human embryonic kidney 293 cells (HEK 293). An in vitro study demonstrated that this recombinant virus has the ability to replicate in and lyse some p53-deficient human tumor cells such as human glioma tumor cells (U251) and human bladder cells (EJ), but not in some cells with functional p53, such as human adenocarcinoma cells (A549) and human fibroblast cells (MRC-5). Also, based on the cytopathic effect (CPE), it was demonstrated, under identical conditions, that the U251 cells were more sensitive to r2/Ad replication than the EJ cells. In this paper, we report that r2/Ad could be very useful in studying the in vitro selective replication of E1B-defective adenovirus and has great potential in cancer gene therapy.
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Working Conditions on the Afterglow Characteristics of Rare-earth Luminous Fibers
Xuefeng Guo,Keqin Zhang,Hongwei Zhang,Mingqiao Ge 한국섬유공학회 2018 Fibers and polymers Vol.19 No.3
To test and clarify the stability of afterglow performance of luminescent fibers can accelerate the step of the commercialized application on luminescent textiles. This work investigated the possible effects of a number of working conditions on the afterglow characteristics of luminous fibers. The fibers in our studies did not show any significant change in their afterglow brightness and duration after storage for 12 months under conditions of constant temperature and humidity, after 5 hours of light exposure, or soaking in water for 4 hours. The insignificant decay appears to follow the same mechanism. Thermal perturbation seemed to cause some changes to the initial brightness and decay time with the best performance being observed at about 80 oC. Moreover, contact with acid or base for 5 minutes only resulted in slight reduction of the afterglow brightness. Our studies thus indicate a high degree of stability of the afterglow performance of the luminous fibers used.
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Xuefeng Zhu,Jian-Hui Wang 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.3
In this paper, the problem of non parametric uncertainty in the active training stage of stroke patients is discussed. On the basis of the nonlinear iterative learning theory, a double iterative compensation learning control is proposed. This method adopts the strategy of double loop iteration which can adjust controller parameters in real time to satisfy the patients’ condition. First, a class of saturated nonlinear functions is introduced to satisfy the requirement of position constraints. Then, reference trajectory self-modified strategy is designed for the initial positioning error. Meanwhile, the iterative compensation controller is designed according to the active torque of the patient, which can provide appropriate power compensation to the affected limb and update the parameters of the iterative learning controller continuously. At last, the convergence condition and its proof are given. The simulation results show the effectiveness and practicability of the proposed double iterative compensation optimal control strategy.
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Xuefeng Bai,Xuemei Zhao,신홍범 J-INSTITUTE 2020 International Journal of Crisis & Safety Vol.5 No.2
Purpose: The outbreak of public health crisis of COVID-19 has caused the Chinese sports industry to suffer a "cold winter" and turned into stagnation from rapid development. Although China's sports industry has been gradually restored under the leadership of the government after the epidemic has been effectively controlled, the internal problems exposed by COVID-19 are still worth pondering. These problems will not only impede the further development of China's sports industry, but also make it difficult to cope with other public health emergency crisis. Method: This study researched the impacts of COVID-19 on Chinese sports industry through literature review and data collation, so as to reflect the existing problems in Chinese sports industry and put forward correspond-ing suggestions. Results: Through summarizing the current situation of impacts, it found COVID- 19 had negative impact on sports competition performance, sports fitness and leisure activities, sports tourism services and education and training industry of sports industry. It caused huge economic losses, even hinders the continue development of these industries. Through the specific analysis of the current situation, this paper believed that the huge losses on small and medium-sized sports enterprises was the reason caused such serious consequences. The reasons are as follows: (1)small and medium-sized sports enterprises lacked plans and capabilities to deal with public health emergency crisis due to their small sale and weak assets; (2)In order to control the spread of COVID-19, Chinese people have adopted a semi-closed life. The loss of physical consumers has a fatal shock to small and medium-sized sports enterprises with a single business model; (3)Small and medium-sized sports enterprises are unable to quickly and effectively resume normal operation after the epidemic situation is under control due to their insuffi-cient recovery capacity. Conclusion: In order to solve the existing problems, the development suggestions about government domi-nantion, enterprises assist for small and medium-sized sports companies are proposed. The suggestions are as follows. (1)public health emergency crisis plan for small and medium-sized sports enterprises is established in Chi-na to ensure that small and medium-sized sports enterprises can make timely and effective response when public health emergency crisis happens. (2)diversified online business is conducted based on big data and the Internet by small and medium-sized sports enterprises under the premise of effective supervision, so as to solve the prob-lem of single operation mode and poor pressure-resistant ability of small and medium-sized sports enterprises. (3)epidemic sports industry insurance is carried out to create GDP and enhance the ability of small and medium-sized sports enterprises to resume normal operation.
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Xuefeng Hu,Meng Zhang,Yongchao Li,Linpeng Li,Guiyang Wu 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3
This paper presents a ripple-free input current modified interleaved boost converter for high step-up applications. By integrating dual coupled inductors and voltage multiplier techniques, the proposed converter can reach a high step-up gain without an extremely high turn-ON period. In addition, a very small auxiliary inductor employed in series to the input dc source makes the input current ripple theoretically decreased to zero, which simplifies the design of the electromagnetic interference (EMI) filter. In addition, the voltage stresses on the semiconductor devices of the proposed converter are efficiently reduced, which makes high performance MOSFETs with low voltage rated and low resistance rDS(ON) available to reduce the cost and conduction loss. The operating principles and steady-state analyses of the proposed converter are introduced in detail. Finally, a prototype circuit rated at 400W with a 42-50V input voltage and a 400V output voltage is built and tested to verify the effectiveness of theoretical analysis. Experimental results show that an efficiency of 95.3% can be achieved.
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Parallel Shunt for the Treatment of Transjugular Intrahepatic Portosystemic Shunt Dysfunction
Xuefeng Luo,Ling Nie,Jiaywei Tsauo,Zhu Wang,Chengwei Tang,Xiao Li 대한영상의학회 2013 Korean Journal of Radiology Vol.14 No.3
Objective: To investigate the safety, efficacy and long-term patency of parallel shunts (PS) in the management of the transjugular intrahepatic portosystemic shunt (TIPS) dysfunction. Materials and Methods: Between March 2007 and October 2010, 18 patients (13 men and 5 women) who underwent TIPS revision with the creation of PS were evaluated retrospectively. In the first 10 patients, a 10-mm-diameter Wallgraft endoprosthesis was deployed; in the latter 8 patients, an 8-mm-diameter Fluency endoprosthesis was deployed. Results: The creation of PS was technically successful in all patients. The mean ± standard deviation portosystemic pressure gradient before and after the procedure was 25.5 ± 7.3 mm Hg (range, 16-37 mm Hg) and 10.9 ± 2.3 mm Hg (range, 7-16 mm Hg), respectively. The duration of follow-up was 16.7 ± 10.8 months (range, 6-42 months). The primary shunt patency rates at 12 months after the creation of PS was 70% with Wallgraft endoprostheses and 87.5% with Fluency endoprostheses. Conclusion: TIPS revision with the creation of PS is a safe, effective and durable method for treating shunt dysfunction.
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