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1基于撬棒并联动态电阻的自适应双馈风力发电机低电压穿越显示文摘当电网故障引起电压跌落时,为防止大装机容量风电场的风机脱网,双馈风力发电机(DFIG)多采用Crowbar电路来实现低电压穿越(LVRT)。传统Crowbar电路采用固定阻值的电阻,很难兼顾对转子电流和直流母线电压的抑制以及对Crowbar的投入工作时间的控制。针对传统Crowbar的不足提出了一种基于Crowbar并联动态电阻的双馈风力发电机低电压穿越方案,制定了该方案的自适应控制策略以及其阻值的整定方法。仿真分析不同跌落深度下所提方案的LVRT特性,并与改变IGBT的导通脉宽的变电阻Crowbar方案进行了比较,结果表明带并联动态电阻Crowbar方案的LVRT效果较好,不仅兼顾了对转子过电流和直流母线过电压的抑制,而且在电压深度跌落时可缩短Crowbar的投入时间,有利于系统电压的恢复。张曼 姜惠兰 2014电工技术学报2014,29,2:37
2Improving bubble-particle attachment during the flotation of low rank coal by surface modification显示文摘Based on the problems caused by many oxygen-containing functional groups and poor floatability on the surface of low rank coal,the characteristics of low rank coal were analyzed systematically by means of scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-Ray photoelectron spectroscopy(XPS)techniques.The bubble-particle induction time was used to determine the characterization of the bubble-particle attachment,and the bubble-particle attachment of low rank coal modified by soaking the coal samples in an acid or alkaline solution was analyzed.The floatability of the modified coal surface was verified by flotation tests.The results show that the particle size of 0.125–0.074 mm of the coal sample exhibited better bubble-particle attachment characteristics.The small bubble,the larger approach velocity of bubble and the larger bubble deformation were more helpful to enhance the bubbleparticle attachment.For an acid solution,the smaller the p H was and the longer the soaking time was,the better the floatability of the coal sample and the higher the combustible material recovery were.The combustible material recovery of low rank coal was increased to 78.79%by soaking the sample in an acid solution of pH=0 for 180 min.On the contrary there was a best concentration for the alkaline solution.Haishan Hu Ming Li Lulu Li Xiuxiang Tao 2020International Journal of Mining Science and Technology2020,30,2:27
3Neuronal autophagy aggravates microglial inflammatory injury by downregulating CX3CL1/fractalkine after ischemic stroke显示文摘Ischemic stroke often induces excessive neuronal autophagy, resulting in brain damage; meanwhile, inflammatory responses stimulated by ischemia exacerbate neural injury. However, interactions between neuronal autophagy and microglial inflammation following ischemic stroke are poorly understood. CX3CL1/fractalkine, a membrane-bound chemokine expressed on neurons, can suppress microglial inflammation by binding to its receptor CX3CR1 on microglia. In the present study, to investigate whether autophagy could alter CX3CL1 expression on neurons and consequently change microglial inflammatory activity, middle cerebral artery occlusion(MCAO) was established in Sprague-Dawley rats to model ischemic stroke, and tissues from the ischemic penumbra were obtained to evaluate autophagy level and microglial inflammatory activity. MCAO rats were administered 3-methyladenine(autophagy inhibitor) or Tat-Beclin 1(autophagy inducer). Western blot assays were conducted to quantify expression of Beclin-1, nuclear factor kappa Bp65(NF-κB), light chain 3B(LC3B), and CX3CL1 in ischemic penumbra. Moreover, immunofluorescence staining was performed to quantify numbers of LC3B-, CX3CL1-, and Iba-1-positive cells in ischemic penumbra. In addition, enzyme linked immunosorbent assays were utilized to analyze concentrations of tumor necrosis factor alpha(TNF-α), interleukin 6(IL-6), interleukin 1 beta(IL-1β), and prostaglandin E2(PGE2). A dry/wet weight method was used to detect brain water content, while 2,3,5,-triphenyltetrazolium chloride staining was utilized to measure infarct volume. The results demonstrated that autophagy signaling(Beclin-1 and LC3B expression) in penumbra was prominently activated by MCAO, while CX3CL1 expression on autophagic neurons was significantly reduced and microglial inflammation was markedly activated. However, after inhibition of autophagy signaling with 3-methyladenine, CX3CL1 expression on neurons was obviously increased, whereas Iba-1 and NF-κB expression was downregulated; TNF-α, IL-6, IL-1β, and PGE2 levels were decreased; and cerebral edema was obviously mitigated. In contrast, after treatment with the autophagy inducer Tat-Beclin 1, CX3CL1 expression on neurons was further reduced; Iba-1 and NF-κB expression was increased; TNF-α, IL-6, IL-1β, and PGE2 levels were enhanced; and cerebral edema was aggravated. Our study suggests that ischemia-induced neuronal autophagy facilitates microglial inflammatory injury after ischemic stroke, and the efficacy of this process may be associated with downregulated CX3CL1 expression on autophagic neurons.Hong-Yun He Lu Ren Tao Guo Yi-Hao Deng 2019Neural Regeneration Research2019,14,2:25
4Numerical analysis of application for induction caving roof显示文摘New method for handling roof of the base successive mining is proposed, which is induction caving in the roof. The key is that it is made certain to the station of the space-time in the induction caving roof, as the stress is released with the mining process. And applying the catastrophe theory, the influencing factors of induction caving roof are studied in the emptied areas, such as the mechanical property of the surrounding rock, the area of the gob,the scope and dimension of tensile stress. The results show that the key factor is the area of the gob to the method of the induction caving roof. Then according to the geology and the ore characteristic, the three dimension FEM mechanical model is built in Tongkeng Mine, the laws of the tensile stress are analyzed to the space and the time in the roof with the mining, then it is rational design to the mine step and time of the handing the roof.HU Jian-hua ZHOU Ke-ping LI Xi-bing YANG Nian-ge SU Jia-hong 2005Journal of Central South University of Technology2005,12,z1:22
5Combined chemo-radiotherapy in locally advanced nasopharyngeal carcinomas显示文摘AIM:To provide efficacy and safety data about the combined use of radiotherapy and chemo-radiotherapy in nasopharyngeal carcinoma(NPC).METHODS:We reviewed data of 40 patients with locally advanced NPC treated with induction chemotherapy followed by concomitant chemo-radiotherapy(CCRT)(22/40 patients)or CCRT alone(18/40)from March 2006 to March 2012.Patients underwent fiberoscopy with biopsy of the primitive tumor,and computed tomography scan of head,neck,chest and abdomen with and without contrast.Cisplatin was used both as induction and as concomitant chemotherapy,while 3D conformal radiation therapy was delivered to the nasopharynx and relevant anatomic regions(total dose,70 Gy).The treatment was performed using 6 MV photons of the linear accelerator administered in 2 Gy daily fraction for five days weekly.This retrospective analysis was approved by the review boards of the participating institutions.Patients gave their consent to treatment and to anonymous analysis of clinical data.RESULTS:Thirty-three patients were males and 7 were females.Median follow-up time was 58 mo(range,1-92 mo).In the sub-group of twenty patients with a follow-up time longer than 36 mo,the 3-year survival and disease free survival rates were 85%and 75%,respectively.Overall response rate both in patients treated with induction chemotherapy followed by CCRT and in those treated with CCRT alone was 100%.Grade 3 neutropenia was the most frequent acute side-effect and it occurred in 20 patients.Grade 2 mucositis was seen in 29 patients,while grade 2 xerostomia was seen in 30 patients.Overall toxicity was manageable and it did not cause any significant treatment delay.In the whole sample population,long term toxicity included grade 2 xerostomia in 22 patients,grade 1 dysgeusia in 17 patients and grade 1 subcutaneous fibrosis in 30 patients.CONCLUSION:Both CCRT and induction chemotherapy followed by CCRT showed excellent activity in locally advanced NPC.The role of adjuvant chemotherapy remains to be defined.Francesco Perri Giuseppina Della Vittoria Scarpati Carlo Buonerba Giuseppe Di Lorenzo Francesco Longo Paolo Muto Concetta Schiavone Fabio Sandomenico Francesco Caponigro 2013World Journal of Clinical Oncology2013,4,2:22
6Advances in nutritional therapy in inflammatory boweldiseases:Review显示文摘Inflammatory bowel diseases(IBD), including ulcerative colitis and Crohn's disease are chronic, life-long, and relapsing diseases of the gastrointestinal tract. Currently, there are no complete cure possibilities, but combined pharmacological and nutritional therapy may induce remission of the disease. Malnutrition and specific nutritional deficiencies are frequent among IBD patients, so the majority of them need nutritional treatment, which not only improves the state of nutrition of the patients but has strong anti-inflammatory activity as well. Moreover, some nutrients, from early stages of life are suspected as triggering factors in the etiopathogenesis of IBD. Both parenteral and enteral nutrition is used in IBD therapy, but their practical utility in different populations and in different countries is not clearly established, and there are sometimes conflicting theories concerning the role of nutrition in IBD. This review presents the actual data from research studies on the influence of nutrition on the etiopathogenesis of IBD and the latest findings regarding its mechanisms of action. The use of both parenteral and enteral nutrition as therapeutic methods in induction and maintenance therapy in IBD treatment is also extensively discussed. Comparison of the latest research data, scientific theories concerning the role of nutrition in IBD, and different opinions about them are also presented and discussed. Additionally, some potential future perspectives for nutritional therapy are highlighted.Andrzej Wędrychowicz Andrzej Zając Przemysław Tomasik 2016World Journal of Gastroenterology2016,22,3:21
7电网电压跌落下双馈风力发电机组暂态性能的比较分析显示文摘为了较全面地研究不同运行工况下并网双馈风力发电机组的暂态运行性能,该文基于双馈发电机电磁暂态模型,采用等效集中质量法,建立了考虑风力机和发电机之间传动轴扭转柔性的风力机两个质量块等效模型。在此基础上,基于定子电压定向的矢量控制策略,对风电机组在不同风力机输出转矩、不同电网电压跌落和不同故障持续时间下分别进行了暂态运行性能的仿真,并对风力机不同质量块等效模型的结果进行比较。结果表明,双馈风力发电机组暂态性能与风力机传动链柔性、电压跌落程度和故障持续时间等密切相关。李辉 叶仁杰 韩力 王荷生 Chen Z 2010太阳能学报2010,31,6:14
8Influences of different types of magnetic fields on HCFC-141b gas hydrate formation processes显示文摘In this study, visualizations and experiments are carried out on the influence of static and rotating magnetic fields on the characteristics of HCFC-141b gas hydrate formation, such as crystallization form, formation temperature and induction time. It has been found that a proper rotating magnetic field can considerably improve the low-pressure gas hydrate formation process, especially in increasing the formation temperature and shortening the induction time. The mor- phology of the gas hydrate formation appears rather complex and compact. However, a proper static magnetic field can make the gas hydrate crystal more organized, which will be benefit to heat transfer.SHU Bifen MA Xiaolin GUO Kaihua LI Jianhong 2004Science China Chemistry2004,47,5:14
9A transient energy function for power systems including the induction motor model显示文摘A construction method for power system transient energy function is studied in the paper, which is simple and universal, and can unify the forms of some current en- ergy functions. A transient energy function including the induction motor model is derived using the method. The unintegrable term is dealt with to get an approxi- mate energy function. Simulations in a 3-bus system and in the WSCC 4-generator system verify the validity of the proposed energy function. The function can be applied to direct transient stability analysis of multi-machine large power systems and provides a tool for analysis of the interaction between the generator angle stability and the load voltage stability.MIN Yong CHEN Lei 2007Science China(Technological Sciences)2007,50,5:12
10Fundamental mechanisms and phenomena of clathrate hydrate nucleation显示文摘Insights into the mechanism of hydrate nucleation are of great significance for the development of hydrate-based technologies,hydrate relevant flow assurance,and the exploration of in situ natural gas hydrates.Compared with the thermodynamics of hydrate formation,understanding the nucleation mechanism is challenging and has drawn substantial attention in recent decades.In this paper,we attempt to give a comprehensive review of the recent progress of studies of clathrate hydrate nucleation.First,the existing hypotheses on the hydrate nucleation mechanism are introduced and discussed.Then,we summarize recent experimental studies on induction time,a key parameter evaluating the velocity of the nucleation process.Subsequently,the memory effect is particularly discussed,followed by the suggestion of several promising research perspectives.Jinlong Cui Zhenfeng Sun Xiaohui Wang Bin Yu Shudong Leng Guangjin Chen Changyu Sun 2019Chinese Journal of Chemical Engineering2019,27,9:11
11Dynamic equivalent method of interconnected power systems with consideration of motor loads显示文摘The existing equivalent methods usually only deal with static load models and neglect the dynamic characteristics of loads such as induction motors.This paper presents a dynamic equivalent method which considers motor dynamics.At first,the clustering criterion of motor loads is given.The motors with similar dynamic characteristics are classified into one group.Then,reduction of motors in the same group is carried out.Finally,parameters of the equivalent motor are calculated and the equivalent system is thus obtained.This aggregation method is applied to the New England system of 39-buses and 10-generators.Simulation results show that the equivalent system retains the dynamic performance of the original system with good accuracy.Compared with the 1-motor equivalent scheme,the 2-motor equivalent scheme can improve equivalent precision effectively.ZHOU HaiQiang1,JU Ping1,YANG Hui1 & SUN Ran2 1 Electrical Engineering School,HoHai University,Nanjing 210098,China 2 Henan Power Dispatching & Communication Center,Zhengzhou 450052,China 2010Science China(Technological Sciences)2010,53,4:10
12Metabolomic Analysis of Serum Glycerophospholipid Levels in Eosinophilic and Neutrophilic Asthma显示文摘Objective To compare the serum glycerophospholipid levels in the inflammatory subtypes of asthma by using targeted metabolomic analysis. Methods Demographic and clinical data were collected from 51 patients with asthma between January 2015 and December 2015. Routine blood and sputum induction tests were performed. Eosinophilic asthma was defined as induced sputum containing ≥ 3% eosinophils, and neutrophilic asthma, as induced sputum containing ≥ 71% neutrophils. Serum metabolic glycerophospholipid profile was determined by liquid chromatography-mass spectrometry. Differences in glycerophospholipid levels between eosinophilic and non-eosinophilic asthma and between neutrophilic and non-neutrophilic asthma were analyzed using partial least squares discriminant analysis. Results The serum lysophosphatidylglycerol level was significantly higher in the group with ≥ 3% eosinophils in sputum than in the group with < 3% eosinophils in sputum. The area under the receiver-operating characteristic curve was ≥ 70%. There was no significant difference in the serum metabolic glycerophospholipid profile between the group with sputum neutrophils ≥ 71% and the group with sputum neutrophils < 71%. Conclusion Serum lysophosphatidylglycerol is produced abundantly in eosinophilic asthma and may be a biomarker of eosinophilic asthma. This information is helpful for identifying and tailoring treatment for the common asthma subtypes.GAI Xiao Yan ZHANG Li Jiao CHANG Chun GUO Cheng Lin ABULIKEMU Mairipaiti LI Wen Xiong WANG Juan YAO Wan Zhen ZHANG Xu 2019Biomedical and Environmental Sciences2019,32,2:8
13Induction of c-fos/c-myc expression by epidermal growth factor decreases with alteration of their gene binding proteins in senescent fibroblasts显示文摘Inductionofcfos/cmycexpresionbyepidermalgrowthfactordecreaseswithalterationoftheirgenebindingproteinsinsenescentfibroblasts...毛泽斌 张宗玉 童坦君 1997Chinese Medical Journal1997,,10:8
14Energy dependence on modes of electric activities of neuron driven by different external mixed signals under electromagnetic induction显示文摘Energy supply and release play an important role in individual neuron and neural network. In this paper, the electrical activities and Hamilton energy of neuron are investigated when external mixed signals(i.e., the periodic stimulus current and the periodic electromagnetic field) are imposed on the neuron under the electromagnetic induction. As a result, the Hamilton energy is much dependent on the mode transition, the multiple electric activity modes and the numerical analysis of Hamilton energy are more complicated under various parameters. When the periodic high-low frequency electromagnetic radiation is imposed in neuron, it is found that the electrical activities are more complex, and the changing of energy is obvious. In addition, the response of electrical activity and Hamilton energy is much dependent on the changing of amplitude A, B when the external high-low frequency signal is imposed on the neuron, meanwhile, the energy of bursting state is lower than the one of spiking state. It can be used for investigation about the energy coding in the neuron even the neuron networks.LU LuLu JIA Ya XU Ying GE MengYan YANG LiJian ZHAN Xuan 2019Science China(Technological Sciences)2019,62,3:8
15Effects of magnetic fields on HCFC-141b refrigerant gas hydrate formation显示文摘Low-pressure refrigerant gas hydrates have brilliant prospects as a cool storage me-dium for air-conditioning systems. Intensive effects of some specific magnetic fields on the forma-tion process of HCFC-141b refrigerant gas hydrate are depicted experimentally. Under influence of these specific magnetic fields, the orientation and growth region of gas hydrate are altered; induc-tion time of hydrate crystallization can be shortened extremely, and it can be shortened to 40 min from 9 h; hydrate formation mass can be enhanced considerably, and hydration rate can arrive at 100% in some instances. Meanwhile, the relations of induction time and hydration rate changed with magnetic field intensity are depicted, and some elementary regulations are found.刘勇 郭开华 梁德青 樊栓狮 2003Science China Chemistry2003,46,4:6
16基于滑模磁链观测器的感应电机模型预测控制显示文摘感应电机模型预测控制通过系统状态预测的方法,利用设计好的目标函数直接控制磁链和转矩。该方案易于实现多变量控制和处理非线性约束,但因为预测过程需要使用电机的真实磁链,所以对磁链观测的精度有很高的要求,以滑模磁链观测器替代传统的电流模型和电压模型磁链观测器可大大提高该方案的控制性能。常规的滑模磁链观测器依据电流观测误差设计滑模控制函数,在实现对转子电阻变化的高鲁棒性的同时也引入了定子电阻变化的影响。文章中提出一种基于磁链观测误差的滑模控制函数设计方法,对滑模观测器的性能进行改进。因为磁链的真实值无法直接获取,磁链误差值以近似计算的方式得到。通过仿真和物理实验验证了该方案对电机参数变化的高鲁棒性。孙佳将 卢勇辉 赵金 2019微电机2019,52,5:6
17华山松疱锈病的重寄生真菌(深绿木霉)中几丁质酶基因cDNA片段的克隆(英文)显示文摘[Objective] The aim of this study was to isolate chitinase gene from Trichoderma atroviride strain SS003. [Method] With the aeciospore wall of armandii pine blister rust as inducer, chitinase gene was induced to express in Trichoderma atroviride cells. The cDNA fragment of chitinase gene was cloned by RT-PCR approach. [Result] The activity of chitinase induced reached 40.17 μg/10 min; and the specific fragment amplified was 834 bp in length and proved to be the fragment of chitinase gene by sequencing and sequence analysis. [Conclusion] The result showed the feasibility of isolating the full length of chitinase gene and its transformation, and further producing chitinase.马长乐 李靖 陈玉惠 刘小烛 2008Agricultural Science & Technology2008,9,6:5
18The incidence of oxygen desaturation during rapid sequence induction and intubation显示文摘BACKGROUND: Rapid sequence induction and intubation(RSII) is an emergency airway management technique for patients with a risk of pulmonary aspiration. It involves preoxygenation, administration of predetermined doses of induction and paralytic drugs, avoidance of mask ventilation, and laryngoscopy followed by tracheal intubation and keeping cricoid pressure applied till endotracheal tube cuff be inflated. Oxygen desaturation has been seen during RSII. We assessed the incidence of oxygen desaturation during RSII.METHODS: An institution-based observational study was conducted from March 3 to May 4, 2014 in our hospital. All patients who were operated upon under general anesthesia with RSII during the study period were included. A checklist was prepared for data collection.RESULTS: A total of 153 patients were included in this study with a response rate of 91.6%. Appropriate drugs for RSII, equipments for RSII, equipments for diffi cult intubation, suction machine with a catheter, a monitor and an oxygen backup such as ambu bag were not prepared for 41(26.8%), 50(32.7%), 51(33.3%), 38(24.8%) and 25(16.3%) patients respectively. Cricoid pressure was not applied at all for 17(11.1%) patients and 53(34.6%) patients were ventilated after induction of anesthesia but before intubation and endotracheal cuff inflation. A total of 55(35.9%) patients desaturated during RSII(SPO2<95%). The minimum, maximum and mean oxygen desaturations were 26%, 94% and 70.9% respectively. The oxygen desaturation was in the range of <50%, 50%–64%, 65%–74%, 75%–84%, 85%–89 % and 90%–94% for 6(3.9%), 7(4.6%), 5(3.3%), 10(6.5%), 13(8.5%) and 14(9.2%) patients respectively.CONCLUSION: The incidence of oxygen desaturation during RSII was high in our hospital. Preoperative patient optimization and training about the techniques of RSII should be emphasized.Endale Gebreegziabher Gebremedhn Desta Mesele Derso Aemero Ehtemariam Alemu 2014World Journal of Emergency Medicine2014,5,4:5
19Fluid Flow and Heat Transfer in a Continuous Casting Tundish With the Channel Type Induction Heating显示文摘A coupled mathematical model was developed to describe the flow field,temperature distribution of molten steel in the tundish with the channel type induction heating.The molten steel motion was dominated under the combined effect of the thermal buoyancy and the electro-magnetic forces(EMFs)due to the channel type induction heating.The results indicate that the thermal loss of molten steel in the tundish can be compensated effectively by the channel type induction heating.In addition,the molten steel would flow upward under the thermal buoyancy which can reduce the erosion of refractory.Moreover,the upward flow would increase the residence time of the molten steel in the tundish which provide more opportunities for the inclusion to reach the top surface of the tundish.WANG Qiang WANG Fang WANG Bo LIU Zhong-qiu LI Bao-kuan 2012Journal of Iron and Steel Research(International)2012,19,S2:5
20INDUCTION PLASMA REACTIVE DEPOSITION OF TUNGSTEN CARBIDE FROM TUNGSTEN METAL POWDER显示文摘Experimental results are reported on the primary carburization reaction between the tungsten powder and methane in the induction plasma, and the secondary carburiza tion of the deposit on substrate at high temperature. Optical microscopy and scanning electron microscopy were used to examine the microstructures of starting tungsten powder, carburized powder, and deposit. X-ray diffraction analysis, thermal gravimet ric analysis and microhardness measurement were used to characterize the structures and properties of the powder and the deposit. It is found that the primary carbur ization reaction in the induction plasma starts from the surface of tungsten particles when the particles are melted. Tungsten particles are partially carburized inside the reactive plasma. Complete carburization is achieved through the secondary carburiza tion reaction of the deposit on substrate at high temperature.X.L. Jiang Institute of Surface and Coatings Technology, Central South University, Changsha 410083, China M.I. Boulos Department of Chemical Engineering, University of Sherbrooke, Sherbrooke, J1K 2R1, Canada 2001Acta Metallurgica Sinica(English Letters)2001,14,5:4
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