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159篇 您的检索式:作者名="Jianjun Feng"
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1Chinese deserts and sand fields in Last Glacial Maximum and Holocene Optimum显示文摘The Last Glacial Maximum (LGM, c. 26-16 ka) and the Holocene Optimum (HO, c. 9-5 ka) were characterized by cold-dry and warm-wet climates respectively in the recently geological Earth. How Chinese deserts and sand fields responded to these distinctive climatic changes is still not clear, however. To reconstruct environments of the deserts and sand fields during the LGM and HO is helpful to understand the forcing mechanisms of environment change in this arid region, and to test paleoclimatic modeling results. Through our long-term field and laboratory investigations, 400 optically stimulated luminescence (OSL) ages and more than 100 depositional records in the Chinese deserts and sand fields were obtained; on the basis of these data, we reconstruct spatial distributions of the deserts and sand fields during the LGM and HO. Our results show that the sand fields of Mu Us, Hunshandake, Horqin and Hulun Buir in northern and northeastern China had expanded 25%, 37%, 38% and 270%, respectively, during the LGM; the sand fields of Gonghe in the northeastern Qinghai-Tibetan Plateau had expanded 20%, and the deserts of Badain Jaran, Tengger in central northern China had expanded 39% and 29% separately during the LGM; the deserts of Taklimakan, Gurbantünggüt and Kumtag in northwestern China had expanded 10%-20% respectively, compared to their modern areas. On the other hand, all of the sand fields were nearly completely covered by vegetation during the HO; the deserts in northwestern and central northern China were reduced by around 5%-20% in area during this time. Lakes in this arid region were probably expanded during the HO but this conclusion needs more investigation. Compared with the geological distributions of deserts and sand fields, human activity has clearly changed (expanded) the area of active sand dunes at the present time. Our observations show that environmental conditions of Chinese deserts and sand fields are controlled by regional climate together with human activity.LU HuaYu YI ShuangWen XU ZhiWei ZHOU YaLi ZENG Lin ZHU FangYing FENG Han DONG LiNa ZHUO HaiXin YU KaiFeng MASON Joseph WANG XiaoYong CHEN YingYong LU Qi WU Bo DONG ZhiBao QU JianJun WANG XunMing GUO ZhengTang 2013Chinese Science Bulletin2013,58,23:40
2Short-chain fatty acids act as antiinflammatory mediators by regulating prostaglandin E_2 and cytokines显示文摘AIM:To investigate the effect of short-chain fatty ac-ids (SCFAs) on production of prostaglandin E2 (PGE2),cytokines and chemokines in human monocytes.METHODS:Human neutrophils and monocytes were isolated from human whole blood by using 1-Step Polymorph and RosetteSep Human Monocyte Enrich-ment Cocktail,respectively. Human GPR41 and GPR43 mRNA expression was examined by quantitative real-time polymerase chain reaction. The calcium flux assay was used to examine the biological activities of SCFAs in human neutrophils and monocytes. The effect ofSCFAs on human monocytes and peripheral blood mononuclear cells (PBMC) was studied by measuring PGE2,cytokines and chemokines in the supernatant. The effect of SCFAs in vivo was examined by intraplantar injection into rat paws.RESULTS:Human GPR43 is highly expressed in human neutrophils and monocytes. SCFAs induce robust calcium flux in human neutrophils,but not in human monocytes. In this study,we show that SCFAs can in-duce human monocyte release of PGE2 and that this effect can be enhanced in the presence of lipopolysac-charide (LPS). In addition,we demonstrate that PGE2 production induced by SCFA was inhibited by pertussis toxin,suggesting the involvement of a receptor-mediated mechanism. Furthermore,SCFAs can specifi cally inhibit constitutive monocyte chemotactic protein-1 (MCP-1) production and LPS-induced interleukin-10 (IL-10) production in human monocytes without affecting the secretion of other cytokines and chemokines examined. Similar activities were observed in human PBMC for the release of PGE2,MCP-1 and IL-10 after SCFA treatment. In addition,SCFAs inhibit LPS-induced production of tumor necrosis factor-α and interferon-γ in human PBMC. Finally,we show that SCFAs and LPS can induce PGE2 production in vivo by intraplantar injection into rat paws (P < 0.01). CONCLUSION:SCFAs can have distinct antiinflammatory activities due to their regulation of PGE2,cytokine and chemokine release from human immune cells.Mary Ann Cox James Jackson Michaela Stanton Alberto Rojas-Triana Loretta Bober Maureen Laverty Xiaoxin Yang Feng Zhu Jianjun Liu Suke Wang Frederick Monsma Galya Vassileva Maureen Maguire Eric Gustafson Marvin Bayne Chuan-Chu Chou Daniel Lundell Chung-Her Jenh 2009World Journal of Gastroenterology2009,15,44:30
3Changes in global potential vegetation distributions from 1911 to 2000 as simulated by the Comprehensive Sequential Classification System approach显示文摘Vegetation classification models play an important role in studying the response of the terrestrial ecosystem to global climate change. In this paper, we study changes in global Potential Natural Vegetation (PNV) distributions using the Comprehensive Sequential Classification System (CSCS) approach, a technique that combines geographic information systems. Results indicate that on a global scale there are good agreements among maps produced by the CSCS method and the globally well-accepted Holdridge Life Zone (HLZ) and BIOME4 PNV models. The potential vegetation simulated by the CSCS approach has 6 major latitudinal zones in the northern hemisphere and 2 in the southern hemisphere. In mountainous areas it has obvious altitudinal distribution characteristics due to topographic effects. The distribution extent for different PNV classes at various periods has different characteristics. It had a decreasing trend for the tundra and alpine steppe, desert, sub-tropical forest and tropical forest categories, and an increasing trend for the temperate forest and grassland vegetation categories. The simulation of global CSCS-based PNV classes helps to understand climate-vegetation relationships and reveals the dynamics of potential vegetation distributions induced by global changes. Compared with existing statistical and equilibrium models, the CSCS approach provides similar mapping results for global PNV and has the advantage of improved simulation of grassland classes.LIANG TianGang FENG QiSheng CAO JianJun XIE HongJie LIN HuiLong ZHAO Jun REN JiZhou 2012Chinese Science Bulletin2012,57,11:23
4Insult of gastroesophageal reflux on airway: clinical significance of pharyngeal nozzle显示文摘在到最糟的最高的注意在航线上吸烟以及薄雾侮辱的全球付钱的时间,所有人知道两个外长、显著。然而,包括许多医药人员,人们主要不知道 gastroesophageal 倒流(GER ) 怎么糟糕在我们的自己的航线上侮辱。GER 的症状通常被看作心痛和流回,它能主要被容忍。不管多么起来在它出现的地方,去的胃的内容相对地传递食管然后远侧的咽象苛评一样的鸟喙,用作一张嘴,以便生产众多微粒子并且到达oro鼻的洞并且另外引起的航线过敏鼻炎和气喘的攻击,甚至肺的实质损害。它将减少生活质量或甚至使受危险生活。内长的侮辱在呼吸系统出现,但是从消化的道发源的点不是众所周知的并且经常 undiagnosed 并且不正确地对待。导致的航线挑战是的 GER 一个可对待、预防的实体一旦诊断被做,好消除能通过 radiofrequency 或 fundoplication 借助于张开的贲门的生活方式调整,药,或固定被期望。作者王忠高博士承受了它为长并且症状在反倒流外科以后消失了 8 年。这是王忠高博士和他的队工作的一个演讲并且将引起注意到公众以便认出作为吸烟或薄雾从人的本身,然而并非从外面的环境发生的一个可对待的条件做的这个相对未知的实体。Zhonggao Wang Zhiwei Hu Jimin Wu Feng Ji Hongtao Wang Yungang Lai Xiang Gao Yachan Ning Chengchao Zhang Zhitong Li Weitao Liang Jianjun Liu 2015Frontiers of Medicine2015,9,1:21
5From concept to reality-A review to the primary test stand and its preliminary application in high energy density physics显示文摘Pulsed power technology,whereas the electrical energy stored in a relative long period is released in much shorter timescale,is an efficient method to create high energy density physics(HEDP)conditions in laboratory.Around the beginning of this century,China Academy of Engineering Physics(CAEP)began to build some experimental facilities for HEDP investigations,among which the Primary Test Stand(PTS),a multi-module pulsed power facility with a nominal current of 10 MA and a current rising time~90 ns,is an important achievement on the roadmap of the electro-magnetically driven inertial confinement fusion(ICF)researches.PTS is the first pulsed power facility beyond 10 TW in China.Therefore,all the technologies have to be demonstrated,and all the engineering issues have to be overcome.In this article,the research outline,key technologies and the preliminary HEDP experiments are reviewed.Prospects on HEDP research on PTS and pulsed power development for the next step are also discussed.Jianjun Deng Weiping Xie Shuping Feng Meng Wang Hongtao Li Shengyi Song Minghe Xia Ji Ce An He Qing Tian Yuanchao Gu Yongchao Guan Bin Wei Xianbin Huang Xiaodong Ren Jiakun Dan Jing Li Shaotong Zhou Hongchun Cai Siqun Zhang Kunlun Wang Qiang Xu Yujuan Wang Zhaohui Zhang Guilin Wang Shuai Guo Yi He Yiwei Zhou Zhanji Zhang Libing Yang Wenkang Zou 2016Matter and Radiation at Extremes2016,1,1:19
6Effect of dietary supplementation with protease on growth performance,nutrient digestibility, intestinal morphology, digestive enzymes and gene expression of weaned piglets显示文摘This study was conducted to investigate the effect of dietary protease supplementation on the growth performance, nutrient digestibility, intestinal morphology, digestive enzymes and gene expression in weaned piglets. A total of 300 weaned piglets(21 days of age Duroc x Large White x Landrace; initial BW = 6.27 ± 0.45 kg) were randomly divided into 5 groups. The 5 diets were: 1) positive control diet(PC), 2) negative control diet(NC), and 3) protease supplementations, which were 100, 200, and 300 mg per kg NC diet. Results indicated that final BW, ADG, ADFI, crude protein digestibility, enzyme activities of stomach pepsin, pancreatic amylase and trypsin, plasma total protein, and intestinal villus height were higher for the PC diet and the supplementations of 200 and 300 mg protease per kg NC diet than for the NC diet(P < 0.05). Supplementations of 200 and 300 mg protease per kg NC diet significantly increased the ratio of villus height to crypt depth(VH:CD) of duodenum, jejunum and ileum compared with NC diet(P < 0.05). Feed to gain ratio, diarrhea index, blood urea nitrogen, and diamine oxidase were lower for the PC diet and supplementations of 200 and 300 mg protease per kg NC diet than for the NC diet(P < 0.05). Piglets fed the PC diet had a higher peptide transporter 1(PepTl) mRNA abundance in duodenum than piglets fed the NC diet(P < 0.05), and supplementations of 100, 200 and 300 mg protease per kg NC diet increased the PepTl mRNA abundance in duodenum(P < 0.05) comparing with the NC diet. Piglets fed the PC diet had a higher b0,+AT mRNA abundance in jejunum than piglets fed the NC diet(P < 0.05), and supplementations of 200 and 300 mg protease per kg NC diet increased the b0,+AT mRNA abundance in jejunum and ileum comparing with the NC diet(P < 0.05). In summary, dietary protease supplementation increases growth performance in weaned piglets, which may contribute to the improvement of intestinal development, protein digestibility, nutrient transport efficiency, and health status of piglets when fed low digestible protein sources.Jianjun Zuo Baoming Ling Lina Long Tiejun Li Ludovic Lahaye Chengbo Yang Dingyuan Feng 2015Animal Nutrition2015,,4:18
7Leakage Prediction Method for Contacting Mechanical Seals with Parallel Faces显示文摘Since the beginning of the 20th century, many researches on the sealing characteristic of mechanical seals were carried out broadly and in depth by various methods and some leakage models were built. But due to the lack of the way to characterize the main factors of influence on the leakage, most of the early researches were based on the assumptions that the seal faces topography and the frictional conditions were invariant. In the early built models, the effect of the surface topography change of the seal face on the leakage rate was neglected. Based on the fractal theory, the contact of end faces of the rotary and stationary rings was simplified to be the contact of a rough surface and an ideal rigid smooth surface, and the contact interface’s cavity size-distribution function as well as the fractal characteristic of the cavity profile curve was discussed. By analyzing the influence of abrasion on the seal face topography and the leakage channel, the time-correlation leakage prediction model of mechanical seals based on the fractal theory was established and the method for predicting the leakage rate of mechanical seals with parallel plane was proposed. The values of the leakage rate predicted theoretically are similar to the measured values of the leakage rate in the model test and in situ test. The experimental results indicate that the leakage rate of mechanical seals is a transient value. The surface topography of the end faces of the seal rings and its change during the frictional wear of mechanical seals can be accurately characterized by the fractal parameters. Under the work conditions of changeless frictional mechanism, the fractal parameters measured or calculated based on the accelerated testing equation can be used to predict the leakage rate of mechanical seal in service. The proposed research provides the basis for determining the leakage state and predicting working life of mechanical seal.SUN Jianjun WEI Long FENG Xiu GU Boqin 2010Chinese Journal of Mechanical Engineering2010,23,1:16
8Integration of micro-supercapacitors with triboelectric nanogenerators for a flexible self-charging power unit显示文摘便携式、便携的电子设备的快速的发展为灵活、有效的精力收获和存储单位增加了需求。通常,这些作为分离部件独立被造并且使用。此处,我们建议雕刻的简单、划算的激光为制作一个灵活自我控告的 micro-supercapacitor 力量单位(SCMPU ) 的技术,由集成摩擦电, nanogenerator (TENG ) 和 micro-supercapacitor (MSC ) 穿进一台单个设备。SCMPU 能被周围的机械运动直接控告。我们表明 SCMPU 的能力连续地驱动轻射出的二极管和商业温湿计。这调查可以支持持续自我动力的系统的开发并且为 supercapacitors 提供一个有希望的新研究应用程序。Jianjun Luo Feng Ru Fan Tao Jiang Zhiwei Wang Wei Tang Cuiping Zhang Mengmeng Liu Guozhong Cao Zhong Lin Wang 2015Nano Research2015,8,12:14
9Formability of AA 2219-O sheet under quasi-static,electromagnetic dynamic,and mechanical dynamic tensile loadings显示文摘The mechanism by which electromagnetic forming(EMF)enhances the formability of metals is unclear owing to the coupling effect of multi-physics fields.In the present work,the associated formability improvement mechanisms were qualitatively categorized and illustrated.This was realized by comparing the formability of fully annealed 2219 aluminum alloy(AA 2219-O)sheet under quasi-static(QS),electromagnetic dynamic(EM),and mechanical dynamic(MD)tensile loadings.It was found that the forming limit of AA 2219-O sheet under EM tensile loading was significantly(45.4%)higher than that under QS tensile loading,and was marginally(3.7%–4.3%)higher than that under MD tensile loading.In addition,the forming limit of AA 2219-O sheet demonstrated a negative dependency on the strain rate within the range of the dynamic tensile tests conducted.The deformation conditions common to EM and MD tensile loadings were responsible for the significant formability improvement compared with QS tensile loading.In particular,the inertial effect was dominant.The different deformation conditions that distinguish EM tensile loading from MD tensile loading resulted in the marginal improvement in formability.This was caused by the absence of a sustaining contact force at the later deformation stage and the lower strain rate.The body force exerted little influence on the formability improvement,and the thermal effect under the two dynamic tensile loadings was negligible.Hongliang Su Liang Huang Jianjun Li Wang Xiao Hui Zhu Fei Feng Hongwei Li Siliang Yan 2021Journal of Materials Science & Technology2021,,11:13
10De novo mutation in ATP6V1B2 impairs lysosome acidification and causes dominant deafness-onychodystrophy syndrome显示文摘Yongyi Yuan Jianguo Zhang Qing Chang Jin Zeng Feng Xin Jianjun Wang Qingyan Zhu Jing Wu Jingqiao Lu Weiwei Guo Xukun Yan Hui Jiang Binfei Zhou Qi Li Xue Gao Huijun Yuan Shiming Yang Dongyi Han Zixu Mao Ping Chen Xi Lin Pu Dai 2014Cell Research2014,24,11:13
11Passive source range estimation with a single receiver in shallow water显示文摘An approach for long-range passive impulsive source ranging with a single receiver in shallow water is proposed,which utilizes the frequency spectrum of the warped signal autocorrelation function via warping transform.For an ideal waveguide,there are invariable frequency features both in the frequency spectrum of the warped signal corresponding to modal cut-off frequencies and the warped signal autocorrelation function due to modal interference.These intrinsic frequency features can be used to passive source ranging.So,the approximate relationship between the frequency of warped signal at an unknown source range and the intrinsic frequency extracted by the time warping transform is derived.These rules can be generalized to an actual shallow water waveguide.Employing an acoustic model to offer the invariable frequency spectrum features,the impulsive signal data collected by a single hydrophone in the North Yellow Sea in December 2011 are analyzed to verify the proposed source ranging approach.The estimated ranges are in good agreement with the ranges measured by GPS,and the mean relative error of range estimation is less than 10%.QI Yubo ZHOU Shihong REN Yun WANG Dejun LIU Jianjun FENG Xiqiang 2015Chinese Journal of Acoustics2015,34,1:13
12Double-directional control bolt support technology and engineering application at large span Y-type intersections in deep coal mines显示文摘Under deep and complex geological conditions,severe deformation occurs at intersection points of Y-type roadways with large cross sections during engineering projects in coal mines,especially at junction arches.Based on in-situ investigations and theoretical studies,we have summarized typical forms of destruction and identified high stress and unrestricted support at both sides of junction arch as its main causes.In this study,we also presented double-directional control bolt support technology for a large Y-type span intersection,applied to deep intersection engineering in the Jiahe Coal Mine,which has proved effective.GUO, Zhibiao SHI, Jianjun WANG, Jiong CAI, Feng WANG, Fuqiang 2010Mining Science and Technology2010,20,2:12
13Design of structured-light vision system for tomato harvesting robot显示文摘In order to improve the operating precision of the harvesting robot,a vision system for intelligently identifying and locating the mature tomato was designed.The active detection method based on structured-light stereo vision was expected to deal with the problem of variable illumination and target occlusion in the glasshouse.The maximum between-cluster variances of hue(H)and saturation(S)value were adopted as the threshold for color segmentation,which weakened the impact on the image caused by the light intensity variation.Through the limit on the pixel size and circularity of the candidate areas,the vision system recognized the fruit area and removed the noise areas.The fruit’s 3D position was computed on the basis of spatial relationship between the laser plane and the camera,when the linear laser was projected on the centre area of the mature fruit.The blue view-scanning laser stripe pixels on the mature fruit were extracted according to its Cb color characteristic.As the field test results show,the measurement error on the fruit radius is less than 5 mm,the centre distance error between the fruit and camera is less than 7 mm,and the single axis coordinate error is less than 5.6 mm.This structured-light vision system could effectively identify and locate mature fruit.Feng Qingchun Cheng Wei Zhou Jianjun Wang Xiu 2014International Journal of Agricultural and Biological Engineering2014,7,2:12
14The seismic CT method in measuring rock bodies显示文摘地震计算断层摄影术(CT ) 方法从节扫描首先在医药科学使用了的 X 光检查的基本原则被导出。方法在分开的地上凿穿记录在射击和接收装置之间的 P 波浪到达。用从 2D 的速度信息地震 P 波浪到达倒置,我们能在岩石和土壤身体中决定速度的分发。这篇论文介绍使用地震 CT 方法为隧道工程并且到检测岩石的结构的一个实际盒子为做第一到达时间反复的倒置利用 SIRT 算法。与另外的探索方法相比,它更有效、精确。Du Lizhi Zhang Xiaopei Niu Jianjun Wang Xuege Feng Guolei 2006Applied Geophysics2006,3,3:8
15Adsorption-energy-based activity descriptors for electrocatalysts in energy storage applications显示文摘Energy storage technologies, such as fuel cells, ammonia production and lithium–air batteries, are important strategies for addressing the global challenge of energy crisis and environmental pollution.Taking overpotential as a direct criterion, we illustrate in theory and experiment that the adsorption energies of charged species such as Li^++e^-and H^++e^-are a central parameter to describe catalytic activities related to electricity-in/electricity-out efficiencies. The essence of catalytic activity is revealed to relate with electronic coupling between catalysts and charged species. Based on adsorption energy, some activity descriptors such as d-band center, e_g-electron number and charge-transfer capacity are further defined by electronic properties of catalysts that directly affect interaction between catalysts and charged species. The present review is helpful for understanding the catalytic mechanisms of these electrocatalytic reactions and developing accurate catalytic descriptors, which can be employed to screen high-activity catalysts in future high-throughput calculations and experiments.Youwei Wang Wujie Qiu Erhong Song Feng Gu Zhihui Zheng Xiaolin Zhao Yingqin Zhao Jianjun Liu Wenqing Zhang 2018National Science Review2018,5,3:8
16Efficacy of platinum in advanced triple-negative breast cancer with germline BRCA mutation determined by next generation sequencing显示文摘Objective:To compare the efficacy of platinum-and non-platinum-based regimens as first-line treatment for advanced triple-negative breast cancer(TNBC)and analyze the relationship between their efficacy and BRCA gene status.Methods:Retrospectively analyze clinical data of 220 patients diagnosed pathologically with advanced TNBC and treated at the Department of Breast Oncology,Peking University Cancer Hospital from 2013 to 2018 and evaluate the efficacy of chemotherapy.A total of 114 patients had BRCA1/2 gene tested by next generation sequencing(NGS)using peripheral blood,and we analyzed the correlation between their efficacy and BRCA1/2 gene status.Results:Non-platinum-based chemotherapy(NPCT)was administered to 129 and platinum-based chemotherapy(PBCT)to 91 study patients.The clinical benefit rate(CBR)and median progression-free survival(PFS)were not statistically different between NPCT and PBCT groups.The median overall survival(OS)was 30.0 and 22.5 months for PBCT and NPCT group,respectively[P=0.090,hazard ratios(HR)=0.703].BRCA status was assessed in 114 patients,14 of whom had deleterious germline BRCA1/2(g BRCA)mutations(seven in each group).In PBCT group,the CBR was 85.7%and 35.1%for patients with and without deleterious g BRCA mutations,respectively(P=0.039).The median PFS were 14.9 and 5.3 months and median OS were 26.5 and 15.5 months for patients with and without deleterious g BRCA mutations,respectively(P=0.001,P=0.161,respectively).Patients in PBCT group had significantly greater rates of grade 3-4 anemia(5.5%vs.0%)and thrombocytopenia(8.8%vs.0%),whereas palmar-plantar erythrodysesthesia(12.4%vs.0%)and peripheral neuropathy(8.6%vs.1.1%)occurred more frequently in NPCT group.Conclusions:Platinum-based regimens are more effective in patients with deleterious g BRCA mutations,but no difference in patients without BRCA gene mutations,so non-platinum is an option in patients without BRCA gene mutations considering the toxicity and side effect.And we recommend that patients with advanced TNBC should have BRCA gene test.Nan Wang Kun Li Wenfa Huang Weiyao Kong Xiaoran Liu Weijie Shi Feng Xie Hanfang Jiang Guohong Song Lijun Di Quanren Wang Jianjun Yu Huiping Li 2020Chinese Journal of Cancer Research2020,32,2:7
17Co-seismic Faults and Geological Hazards and Incidence of Active Fault of Wenchuan Ms 8.0 Earthquake,Sichuan,China显示文摘There are two co-seismic faults which developed when the Wenchuan earthquake happened. One occurred along the active fault zone in the central Longmen Mts.and the other in the front of Longmen Mts.The length of which is more than 270 km and about 80 km respectively.The co-seismic fault shows a reverse flexure belt with strike of N45°-60°E in the ground,which caused uplift at its northwest side and subsidence at the southeast.The fault face dips to the northwest with a dip angle ranging from 50°to 60°.The vertical offset of the co-seismic fault ranges 2.5-3.0 m along the Yingxiu-Beichuan co-seismic fault,and 1.5-1.1 m along the Doujiangyan-Hanwang fault.Movement of the coseismic fault presents obvious segmented features along the active fault zone in central Longmen Mts. For instance,in the section from Yingxiu to Leigu town,thrust without evident slip occurred;while from Beichuan to Qingchuan,thrust and dextral strike-slip take place.Main movement along the front Longmen Mts.shows thrust without slip and segmented features.The area of earthquake intensity more thanⅨdegree and the distribution of secondary geological hazards occurred along the hanging wall of co-seismic faults,and were consistent with the area of aftershock,and its width is less than 40km from co-seismic faults in the hanging wall.The secondary geological hazards,collapses,landslides, debris flows et al.,concentrated in the hanging wall of co-seismic fault within 0-20 km from co-seismic fault.MA Yinsheng LONG Changxing TAN Chengxuan WANG Tao GONG Mingquan LIAO Chunting WU Manlu SHI Wei DU Jianjun PAN Feng 2009Acta Geologica Sinica(English Edition)2009,83,4:7
18Complete three-dimensional coseismic displacements due to the 2021 Maduo earthquake in Qinghai Province,China from Sentinel-1 and ALOS-2 SAR images显示文摘On 22 nd May 2021(local time),an earthquake of M_(s)7.4 struck Maduo county in Qinghai Province,China.This was the largest earthquake in China since the 2008 Wenchuan earthquake.In this study,ascending/descending Sentinel-1 and advanced land observation satellite-2(ALOS-2)synthetic aperture radar(SAR)images were used to derive the three-dimensional(3-D)coseismic displacements of this earthquake.We used the differential interferometric SAR(In SAR,DIn SAR),pixel offset-tracking(POT),multiple aperture In SAR(MAI),and burst overlap interferometry(BOI)methods to derive the displacement observations along the line-of-sight(LOS)and azimuth directions.To accurately mitigate the effect of ionospheric delay on the ALOS-2 DIn SAR observations,a polynomial fitting method was proposed to optimize range-spectrum-split-derived ionospheric phases.In addition,the 3-D displacement field was obtained by a strain model and variance component estimation(SM-VCE)method based on the high-quality SAR displacement observations.Results indicated that a left-lateral fault slip with the largest horizontal displacement of up to 2.4 m dominated this earthquake,and the small-magnitude vertical displacement with an alternating uplift/subsidence pattern along the fault trace was more concentrated in the near-fault regions.Comparison with the global navigation satellite system data indicated that the SM-VCE method can significantly improve the accuracy of the displacements compared to the classical weighted least squares method,and the incorporation of the BOI displacements can substantially benefit the accuracy of north-south displacement.In addition to the displacements,three coseismic strain invariants calculated based on the strain model parameters were also investigated.It was found that the eastern and western parts of the faults suffered more significant strains compared with the epicenter region.Jihong LIU Jun HU Zhiwei LI Zhangfeng MA Lixin WU Weiping JIANG Guangcai FENG Jianjun ZHU 2022Science China Earth Sciences2022,65,4:6
19Experimental demonstration of transverse mode instability enhancement by a counter-pumped scheme in a 2 kW all-fiberized laser显示文摘Transverse mode instability(TMI)has become the major limitation for power scaling of fiber lasers with nearly diffraction-limited beam quality.Compared with a co-pumped fiber laser,a counter-pumped fiber laser reveals TMI threshold enhancement through a semi-analytical model calculation.We demonstrated a 2 kW high-power counter-pumped all-fiberized laser without observation of TMI.Compared with the co-pumped scheme,the TMI threshold is enhanced at least 50%in counter-pumped scheme,moreover,stimulated Raman scattering and four-wave mixing are suppressed simultaneously.ZEBIAO LI ZHIHUA HUANG XIAOYU XIANG XIAOBAO LIANG HONGHUAN LIN SHANHUI XU ZHONGMIN YANG JIANJUN WANG FENG JING 2017Photonics Research2017,5,2:6
20Experimental study of mode distortion induced by stimulated Raman scattering in high-power fiber amplifiers显示文摘The experimental investigation of mode distortion induced by stimulated Raman scattering(SRS)in a high-power fiber amplifier,which includes the evolutions of optical spectra,spatial beam profiles,and time-frequency characteristics,has been carried out in detail.Temporal-frequency characteristics have been studied for the first time,to the best of our knowledge,by using a low-speed camera and high-speed photodiode traces,which revealed that temporal-frequency characteristics of SRS-induced mode distortion are different from traditional dynamic mode instability(MI).The experimental results show that the output beam profile remains stable before the mode distortion occurs and fluctuates obviously after the onset of SRS-induced MI but on a time scale of seconds,which is much lower than that of Yb-gain-induced MI featuring millisecond-level beam profile fluctuation.It also shows that the mode distortion became measurable in company with the onset of inter-mode four-wave mixing(IM-FWM)when the ratio of Raman light reaches 3%;further,the beam quality factor M2degrades gradually from 1.4 to 2.1 as the ratio of Raman light increases.The mode distortion is accompanied by an obvious temperature increase of the output passive fiber,which further confirms that the mode distortion originates from SRS.The cause of the mode distortion induced by SRS has been explained in the context of core-pumped SRS effect,and the investigation on the accompanying IM-FWM effect indicates that the main content of the SRSinduced high-order mode is the LP21 mode.QIUHUI CHU QIANG SHU ZENG CHEN FENGYUN LI DONGLIN YAN CHAO GUO HONGHUAN LIN JIANJUN WANG FENG JING CHUANXIANG TANG RUMAO TAO 2020Photonics Research2020,8,4:6
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