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| 1 | Reconstruction of precipitation variation from tree rings in recent 1000 years in Delingha, Qinghai显示文摘Using seven well-replicated Qilian juniper (Sabina przewalskii Kom.) ring-width chronologies developed at Zongwulong and Shalike Mts. in the northeastern part of the Qaidam Basin annual precipitation from previous July to current June in the recent 1000 years was re- constructed for Delingha. The reconstruction can capture 63.1% of precipitation variance and the equation was stable over time. For the reconstructed precipitation, wet periods occurred in AD1520—1633 and 1933—2001, whereas dry intervals in 1429—1519 and 1634—1741. In ad- dition, the magnitude in precipitation variation was lower before 1430 with about 15 mm, but it increased to 30 mm during the period of 1430 to 1850. After 1850, the precipitation variance de- creased again. In contrast to the increase in temperature, a decrease in annual precipitation was evident since the 1990s. The agreement in low-frequency variation between the reconstruction and the glacier accumulation and particulate content in Dunde ice cores during the recent several hundred years suggested that the precipitation reconstructed in this study was rather reliable, and represented a regional signal. This 1000-year reconstruction could benefit our understanding of climatic variation in decadal to century-scale in this region, and provide basic data to climate models and to prediction of future climate in the 21st century. | SHAO Xuemei1, HUANG Lei1, LIU Hongbin2, LIANG Eryuan1, FANG Xiuqi3 & WANG Lili1 1. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 2. National Climate Center, Beijing 100081, China 3. Beijing Normal University, Beijing 100875, China | 2005 | Science China Earth Sciences2005，48，7： | 113 |
| 2 | Temperature variations recovered from tree-rings in the middle Qilian Mountain over the last millennium显示文摘Based on the cross-dated tree-ring samples collected from the middle Qilian Moun- tain, a standard ring-width chronology had been developed, which covered the period AD 1000 to 2000. The correlations between the chronology and climatic records from the nearby meteorological stations indicated that temperature was the dominant climatic factor for tree growth at upper timberline, and the most important climatic factor for the tree growth in the area was the mean temperature from previous December to current April. The temperature variations recovered from the ring-width data showed a cold period during the “Little Ice Age” and the con- tinuous warming during the twentieth century. Comparison between the ring-width chronology and δ18O records from the Dunde ice core in the Qilian Mountain indicated that there was a con- sistent trend in both time series. A significant correlation existed between our ring-width chro- nology and the Northern Hemispheric temperature, suggesting that the climate changes in the Qilian Mountain were not only driven by regional factors, but also responsive to the global cli- mate. | LIU Xiaohong1,2, QIN Dahe1, SHAO Xuemei , CHEN Tuo1 & REN Jiawen12 1. Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 2. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China | 2005 | Science China Earth Sciences2005，48，4： | 66 |
| 3 | Prognostic value of red blood cell distribution width for severe acute pancreatitis显示文摘BACKGROUND Severe acute pancreatitis(SAP)is a common condition in the intensive care unit(ICU)and has a high mortality.Early evaluation of the severity and prognosis is very important for SAP therapy.Recently,red blood cell distribution(RDW)was associated with mortality of sepsis patients and could be used as a predictor of prognosis.Similarly,RDW may be associated with the prognosis of SAP patients and be used as a prognostic indicator for SAP patients.AIM To investigate the prognostic value of RDW for SAP patients.METHODS We retrospectively enrolled SAP patients admitted to the ICU of the First Affiliated Hospital of China Medical University from June 2015 to June 2017.According to the prognosis at 90 d,SAP patients were divided into a survival group and a non-survival group.RDW was extracted from a routine blood test.Demographic parameters and RDW were recorded and compared between the two groups.The receiver operator characteristic(ROC)curve was constructed and Cox regression analysis was performed to investigate the prognostic value of RDW for SAP patients.RESULTS In this retrospective cohort study,42 SAP patients were enrolled,of whom 22 survived(survival group)and 20 died(non-survival group).The baseline parameters were comparable between the two groups.The coefficient of variation of RDW(RDW-CV),standard deviation of RDW(RDW-SD),Acute Physiology and Chronic Health Evaluation II(APACHE II)score,and Sequential Organ Failure Assessment(SOFA)score were significantly higher in the non-survival group than in the survival group(P<0.05).The RDW-CV and RDW-SD were significantly correlated with the APACHE II score and SOFA score,respectively.The areas under the ROC curves(AUCs)of RDW-CV and RDW-SD were all greater than those of the APACHE II score and SOFA score,among which,the AUC of RDW-SD was the greatest.The results demonstrated that RDW had better prognostic value for predicting the mortality of SAP patients.When the RDW-SD was greater than 45.5,the sensitivity for predicting prognosis was 77.8%and the specificity was 70.8%.Both RDW-CV and RDW-SD could be used as independent risk factors to predict the mortality of SAP patients in multivariate logistic regression analysis and univariate Cox proportional hazards regression analysis,similar to the APACHE II and SOFA scores.CONCLUSION The RDW is greater in the non-surviving SAP patients than in the surviving patients.RDW is significantly correlated with the APACHE II and SOFA scores.RDW has better prognostic value for SAP patients than the APACHE II and SOFA scores and could easily be used by clinicians for the treatment of SAP patients. | Fang-Xiao Zhang Zhi-Liang Li Zhi-Dan Zhang Xiao-Chun Ma | 2019 | World Journal of Gastroenterology2019，25，32： | 50 |
| 4 | Red blood cell distribution width in heart failure: A narrative review显示文摘The red blood cell distribution width(RDW) is a simple, rapid, inexpensive and straightforward hematological parameter, reflecting the degree of anisocytosis in vivo. The currently available scientific evidence suggests that RDW assessment not only predicts the risk of adverse outcomes(cardiovascular and all-cause mortality, hospitalization for acute decompensation or worsened left ventricular function) in patients with acute and chronic heart failure(HF), but is also a significant and independent predictor of developing HF in patients free of this condition. Regarding the biological interplay between impaired hematopoiesis and cardiac dysfunction, many of the different conditions associated with increased heterogeneity of erythrocyte volume(i.e., ageing, inflammation, oxidative stress, nutritional deficiencies and impaired renal function), may be concomitantly present in patients with HF, whilst anisocytosis may also directly contribute to the development and worsening of HF. In conclusion, the longitudinal assessment of RDW changes over time may be considered an efficient measure to help predicting the risk of both development and progression of HF. | Giuseppe Lippi Gianni Turcato Gianfranco Cervellin Fabian Sanchis-Gomar | 2018 | World Journal of Cardiology2018，10，2： | 37 |
| 5 | Red cell distribution width to platelet ratio: New and promising prognostic marker in acute pancreatitis显示文摘AIM: To evaluate the accuracy of red cell distribution width(RDW) to platelet ratio(RPR) to predict in-hospital mortality in acute pancreatitis(AP).METHODS: Between January 2010 and June 2012, 102 patients with AP were recruited to the study. In this retrospective cohort study, for all subjects, demographic data on hospital admission, AP etiology, comorbid diseases, organ failure assessment, laboratory parameters and length of hospital stay were examined. Additionally, we used a non-invasive prediction method in addition to the RPR to evaluate the disease severity. Multivariate logistic regression analyses were used to evaluate the impact of RPR on hospital admission to predict mortality.RESULTS:The male-female ratio(59/43)was 1.37with a median age of 56.5 years(17-89 years).In both univariate and multivariate analyses,RDW and RPR were presented as independent and significant variables on admission to predict mortality.The RPR obtained on hospital admission was persistently higher amongnon-survivors than among survivors(P<0.0001).The median RPR was 0.000087 in the non-survivor group and 0.000058 in the survivor group.RPR with a cutoff value of 0.000067 presented an area under the curve of 0.783(95%CI:0.688-0.878)in receiver operating characteristic curves and could predict the mortality of approximately 80%of the patients. | Erdin etinkaya Kazim Senol Baris Saylam Mesut Tez | 2014 | World Journal of Gastroenterology2014，20，39： | 38 |
| 6 | Theoretical analysis and experimental investigation on flexural performance of steel reinforced ultrahigh toughness cementitious composite (RUHTCC) beams显示文摘UHTCC (ultrahigh toughness cementitious composite), which is a kind of ultrahigh toughness cemen- titious composites material, exhibits pseudo strain hardening feature when subjected to tension load, and has enormous ductility and prominent crack dispersal ability. Accordingly, UHTCC can improve mechanical behavior of ordinary concrete structure especially its durability, and has been regarded as historical breakthrough to traditional cementitious materials. In this paper, the study focuses on flexure behavior of steel reinforced beam made of UHTCC. Based on the plane section assumption, along with two equilibrium equations of force and moment, the formulae to calculate the flexural load capability for the reinforced ultrahigh toughness cementitious composite (RUHTCC) beam were developed under the assumption that the compression stress- strain relationship in the UHTCC material is a bilinear model. Following this, the simplified formulae were further evolved by effective rectangle stress distribution approach in order to facilitate design of practical engineering. Two effective parameters introduced in effective rectangle approach were determined. The mathematical expressions to evaluate limited rein- forcement ratio, flexural stiffness as well as ductility index were proposed, too. Last, two series of dif- ferent reinforcement ratios of the RUHTCC beams were tested in four-point flexure loading. For com- parison purposes, ordinary RC (reinforced concrete) beams also were prepared. Both moment curva- ture curves and load mid-span displacement curves were recorded and compared with the theoretical calculations. A good agreement between them was found, which validates the proposed theoretical formulae. For ductility index, a slightly big difference between the experimental values and the calcu- lated ones exists. The experimental results show that, compared to control RC beams, the RUHTCC beam can improve both flexural capacity and ductility index, and the degree of improvement will de- crease with the increase in the reinforcement ratio. Particularly, the results also reveal that lager crack width in control beams can be greatly reduced by formation of tightly-spaced fine cracks in UHTCC, which offers more durable structures. | XU ShiLang ZHANG XiuFang | 2009 | Science China(Technological Sciences)2009，52，4： | 18 |
| 7 | Investigation on the Oscillating Buoy Wave Power Device显示文摘An oscillating buoy wave power device (OD) is a device extracting wave power by an oscillating buoy. Being excitedby waves, the buoy heaves up and down to convert wave energy into electricity by means of a mechanical or hydraulic de-vice. Compared with an Oscillating Water Column (OWC) wave power device, the OD has the same capture width ratio as the OWC does, but much higher secondary conversion efficiency. Moreover, the chamber of the OWC, which is the mostexpensive and difficult part to be built, is not necessary for the OD, so it is easier to construct an OD. In this paper, a nu-merical calculation is conducted for an optimal design of the OD firstly, then a model of the device is built and, a model testis carded out in a wave tank. The results show that the total efficiency of the OD is much higher than that of the OWC andthat the OD is a promising wave power device. | 苏永玲 游亚戈 郑永红 | 2002 | China Ocean Engineering2002，17，1： | 11 |
| 8 | The relationship of blood cell-associated inflammatory indices and diabetic retinopathy: a Meta-analysis and systematic review显示文摘AIM: To explore the correlation between several blood cell-associated inflammatory indices including mean platelet volume(MPV), platelet distribution width(PDW), neutrophil to lymphocyte ratio(NLR) and platelet-lymphocyte ratio(PLR), and the presence and severity of diabetic retinopathy(DR). METHODS: We searched for eligible studies from PubMed, EMBASE, Web of Science and CNKI up to December 13, 2017. Standardized mean difference(SMD) calculated with confidence interval(CI) of 95% was used to estimate the values of those indices. RESULTS: A total of 31 studies were included in the present Meta-analysis. As compared with type 2 diabetes mellitus(T2 DM) patients without DR, the values of MPV, PDW, NLR, and PLR were higher in patients with DR(SMD=0.67; 95%CI: 0.36 to 0.98; SMD=0.51; 95%CI: 0.27 to 0.75; SMD=0.77; 95%CI: 0.49 to 1.05 and SMD=1.18; 95%CI: 0.07 to 2.28). Additionally, it was also observed that MPV was closely correlated with the severity of DR. CONCLUSION: MPV, PDW, NLR, and PLR could be recommended as diagnostic biomarkers for DR, and MPV could be applied to assess the severity of DR. | Wen-Juan Luo Wen-Fang Zhang | 2019 | International Journal of Ophthalmology(English edition)2019，12，2： | 10 |
| 9 | Tree-ring-based reconstruction of the April to September mean temperature since 1826 AD for north-central Shaanxi Province,China显示文摘Long-time series of high-resolution temperature record from Chinese Loess Plateau is rare. An April-September mean temperature reconstruction (1826-2004) has been developed for the north-central Shaanxi Province, China, based on tree-ring width analysis. The reconstruction captures 39.3% (p<0.001) of the variance in the instrumental data over the calibration period from 1951 to 2002. The reconstruction shows a high temperature period of 1928-1933, which coincides with the timing of the extreme drought event in 1920s in the entire northern China. The two low temperature periods in reconstruction are 1883-1888 and 1938-1942. With the global warming, the April-September mean temperature in study area has also increased since the 1970s, but has not exceeded the temperature in 1928-1933. Besides the statistical analysis, the reconstruction is also verified by the local dryness/wetness index and other dendroclimatological results. | CAI QiuFang LIU Yu SONG HuiMing SUN JunYan | 2008 | Science China Earth Sciences2008，51，8： | 10 |
| 10 | GW5-Like, a homolog of GW5, negatively regulates grain width, weight and salt resistance in rice显示文摘Grain size is an important determinant of yield potential in crops. We previously demonstrated that natural mutations in the regulatory sequences of qSW5/GW5 confer grain width diversity in rice. However, the biological function of a GW5 homolog, named GW5-Like(GW5 L), remains unknown. In this study, we report on GW5 L knockout mutants in Kitaake, a japonica cultivar(cv.)considered to have a weak gw5 variant allele that confers shorter and wider grains. GW5 L is evenly expressed in various tissues, and its protein product is localized to the plasma membrane. Biochemical assays verified that GW5 L functions in a similar fashion to GW5. It positively regulates brassinosteroid(BR) signaling through repression of the phosphorylation activity of GSK2. Genetic data show that GW5 L overexpression in either Kitaake or a GW5 knockout line, Kasaorf3(indica cv. Kasalath background), causes more slender, longer grains relative to the wild-type. We also show that GW5 L could confer salt stress resistance through an association with calmodulin protein OsCa M1-1. These findings identify GW5 L as a negative regulator of both grain size and salt stress tolerance, and provide a potential target for breeders to improve grain yield and salt stress resistance in rice. | Peng Tian Jiafan Liu Changling Mou Cuilan Shi Huan Zhang Zhichao Zhao Qibing Lin Jie Wang Jiulin Wang Xin Zhang Xiuping Guo Zhijun Cheng Shanshan Zhu Yulong Ren Cailin Lei Haiyang Wang Jianmin Wan | 2019 | Journal of Integrative Plant Biology2019，61，11： | 9 |
| 11 | Prognostic impact of the red cell distribution width in esophageal cancer patients: A systematic review and meta-analysis显示文摘AIM To clarify the previous discrepant conclusions, we performed a meta-analysis to evaluate the prognostic value of red cell distribution width(RDW) in esophageal cancer(EC). METHODS We searched the PubM ed, EMBASE, Web of Science and Cochrane Library databases to identify clinical studies, followed by using STATA version 12.0 for statistical analysis. Studies that met the following criteria were considered eligible:(1) Studies including EC patients who underwent radical esophagectomy;(2) studies including patients with localized disease without distant metastasis;(3) studies including patients without preoperative neoadjuvant therapy;(4) studies including patients without previous antiinflammatory therapies and with available preoperative laboratory outcomes;(5) studies reporting association between the preoperative RDW and overall survival(OS)/disease-free survival(DFS)/cancer-specific survival(CSS); and(6) studies published in English.RESULTS A total of six articles, published between 2015 and 2017, fulfilled the selection criteria in the end. Statistical analysis showed that RDW was not associated with the prognosis of EC patients, irrespective of OS/CSS [hazard ratio(HR) = 1.27, 95% confidence interval(CI): 0.97-1.57, P = 0.000] or DFS(HR = 1.42, 95%CI: 0.96-1.88, P = 0.000). Subgroup analysis indicated that elevated RDW was significantly associated with worse OS/CSS of EC patients when RDW > 13%(HR = 1.45, 95%CI: 1.13-1.76, P = 0.000), when the patient number ≤ 400(HR = 1.45, 95%CI: 1.13-1.76, P = 0.000) and when the study type was retrospective(HR = 1.42, 95%CI : 1.16-1.69, P = 0.000).CONCLUSION Contrary to our general understanding, this meta-analysis revealed that RDW cannot serve as an indicator of poor prognosis in patients with EC. However, it may still be a useful predictor of unfavorable prognosis using an appropriate cut-off value. | Wei-Yu Xu Xiao-Bo Yang Wen-Qin Wang Yi Bai Jun-Yu Long Jian-Zhen Lin Jian-Ping Xiong Yong-Chang Zheng Xiao-Dong He Hai-Tao Zhao Xin-Ting Sang | 2018 | World Journal of Gastroenterology2018，24，19： | 9 |
| 12 | 基于电流环复合控制的有源电力滤波器研究显示文摘为了有效降低非周期信号对三相三线APF控制性能的影响,提出了一种改进重复控制与传统PI控制相串联的双环控制方法。该方法加入了控制前馈和误差比例系数以提高系统对非周期信号的抗扰性能。结合APF在旋转d,q坐标系中的简化数学模型,建立了电压、电流解耦环节,对解耦后的d,q轴电流i d,i q分别进行控制,并采用SVPWM控制策略,以TM320F28335型DSP为处理器,在APF50A样机上进行了实验,实验结果表明了改进的控制算法具有很好的鲁棒性。 | 杨新华 谢斌 | 2014 | 电气传动2014，44，2： | 8 |
| 13 | Is increased red cell distribution width an indicating marker of nonalcoholic steatohepatitis and fibrotic stage?显示文摘AIM:To evaluate the red cell distribution width(RDW)as an indicator of the presence of non-alcoholic steatohepatitis(NASH)and its association with fibrotic scores.METHODS:A retrospective study was carried out that included sixty-two biopsy proven NASH,32 simple steatosis patients and 30 healthy controls.The correlation between the clinical and histopathological features of NASH patients and RDW values was evaluated.Liver fibrosis scores were measured using a 0 to 4 point scale and were divided in to two groups;fibrosis scores0-1 were termed mild and fibrosis scores 2-4 were termed advanced fibrosis.RDW values were compared between NASH,simple steatosis and healthy controls.Univariate and multivariate analyses were performed to evaluate the independent predicting factors for the presence of liver fibrosis caused by NASH.RESULTS:Patients with NASH had higher RDW values compared with simple steatosis and healthy control groups[14.28%±0.25%vs 13.37%±0.12%,12.96%±0.14%(P<0.01),respectively].Patients with advanced fibrosis had higher RDW values than the mild fibrosis group(15.86%±0.4%vs 13.63%±0.67%,P<0.01,respectively).RDW also correlated with fibrotic scores(r=0.579 andP<0.01).The variables that were significant in the univariate analysis were evaluated in multivariate logistic regression analysis,and RDW was an independent predicting factor of NASH(OR=1.75,95%CI:1.129-2.711,P<0.05).CONCLUSION:RDW a new non-invasive marker that can be used to demonstrate the presence of NASH and indicate advanced fibrotic scores. | Mustafa Cengiz Burcu Aslan Candir Güldal Yilmaz Gülen Akyol Seren Ozenirler | 2013 | World Journal of Gastroenterology2013，19，42： | 8 |
| 14 | The 600-mm precipitation isoline distinguishes tree-ring-width responses to climate in China显示文摘The numerous temperature and precipitation reconstructions in China based on tree-ring-width data have played significant roles in furthering the understanding of past climate changes. However, the geographical variability in the responses of trees to climate variations in China remains largely undetermined. Here, we describe an important spatial boundary in the response of trees to climate variations, namely the 600-mm annual precipitation isoline. We found that, to the north of this line, tree-ring widths are usually positively correlated with precipitation and negatively correlated with growing-season temperature. To the south of this line, the tree-ring widths respond positively to temperature, and winter half-year temperatures are the main reconstructed parameters, especially on the third topographical step of China. We also found that precipitation reconstructions based on tree-ring data and the Palmer Drought Severity Index almost exclusively fall in the region of the 200- to 600-mm annual precipitation isolines, not other regions. Our findings indicate that, when using multiple tree-ring-width chronologies for large-scale past climate reconstructions, the climatic signal of each tree-ring-width series should be carefully considered. | Yu Liu Huiming Song Changfeng Sun Yi Song Qiufang Cai Ruoshi Liu Ying Lei Qiang Li | 2019 | National Science Review2019，6，2： | 8 |
| 15 | Effect of Berm Width and Elevation on Irregular Wave Run-Up显示文摘This paper discusses the effect of berm width and elevation of composite slope on irregular wave run-up. Based on the data obtained from model tests, the formula and distribution of irregular wave run-up on composite slope are derived. The changing of wind speed, width and elevation of the berm are considered comprehensively. The wave run-up with various exceedance probability can be es-timated utilizing the distribution curves of irregular wave run-up. | Chen Guoping , Yu Kuang-ming and Zhang Jiachang Assistant Engineer, River and Harbour Department, Nanjing Hydraulic Research Institute, NanjingProf. and Senior Engineer, River and Harbour Department, Nanjing Hydraulic Research Institute, Nanjing Senior Engineer, River and Harbour Department, Nanjing Hydraulic Research Institute, Nanjing | 1991 | China Ocean Engineering1991，6，4： | 7 |
| 16 | Tunable Schottky barrier width and enormously enhanced photoresponsivity in Sb doped SnS2 monolayer显示文摘Doping, which is the intentional introducti on of impurities into a material, can improve the metal-semiconductor interface by reducing Schottky barrier width. Here, we prese nt high-quality two-dime nsional SnS2 nano sheets with well-controlled Sb dopi ng concen tration via direct vapor growth approach and following micromechanical cleavage process. X-ray photoelectro n spectroscopy (XPS) measureme nt dem on strates that Sb contents of the doped samples are approximately 0.22%, 0.34% and 1.21%, respectively, and doping in duces the upward shift of the Fermi level with respect to the pristi ne SnS2. Tran smissio n electro n microscopy (TEM) characterizatio n exhibits that Sb-doped SnS2 nano sheets have a high-quality hexagonal symmetry structure and Sb element is uniformly distributed in the nano sheets. The phototra nsistors based on the Sb-doped SnS2 mono layers show n-type behavior with high mobility which is one order of magn itude higher than that of pristi ne SnS2 phototra nsistors. The photorespo nsivity and exter nal quantum efficiency (EQE) of Sb-S nS2 mono layers phototra nsistors are approximately three orders of magnitude higher than that of pristine SnS2 phototransistor. The results suggest that the method of reducing Shottky barrier width to achieve high mobility and photoresp on sivity is effective, and Sb-doped SnS2 mono layer has significant potential in future nanoelectronic and optoelectronic applications. | Junchi Liu Xiao Liu Zhuojun Chen Lili Miao Xingqiang Liu Bo Li Liming Tang Keqiu Chen Yuan Liu Jingbo Li Zhongming Wei Xidong Duan | 2019 | Nano Research2019，12，2： | 7 |
| 17 | 单片机控制太阳能充电控制器显示文摘针对目前太阳能充电控制器对蓄电池的保护不够充分,蓄电池的寿命缩短这种情况,研究确定了一种基于单片机Atmega16的太阳能充电控制器的方案。本设计使用低功耗、高性能的Atmega16单片机作为核心器件对整个电路进行控制。系统硬件电路由太阳能电池充电电路、电压采集和显示电路、单片机控制电路和RS-485串口通信电路组成,主要实现对蓄电池电压的采集和显示。软件部分依据PWM(pulse width modulation)脉宽调制控制策略,编制程序使单片机输出PWM控制信号,控制信号将实现对功率开关器件MOS管开通与关断的控制,从而实现太阳能极板对蓄电池的充电控制[1]。根据控制器的要求,编制软件程序,软件实现蓄电池高效率充电,使蓄电池不过充、过放,保护蓄电池,延长蓄电池使用寿命。 | 李作文 于海月 | 2015 | 光电技术应用2015，30，3： | 7 |
| 18 | Carrier dynamic overlapping switching frequency optimal pulse width modulation method for modular multilevel converters显示文摘Modular multilevel converters(MMCs) operate in the low modulation index region in many applications.However, when utilized at the low modulation index region, large harmonics appear in the output voltage, which degrade the performance of the MMC. To improve the harmonic characteristic in the low modulation index, the carrier dynamic overlapping switching frequency optimal pulse width modulation(CDOSFOPWM) method is proposed for the MMC here. The whole modulation index region is divided into three regions: high modulation index region, middle modulation index region, and low modulation index region. The carrier amplitude, carrier overlap ratio, and frequency of triangular carriers are chosen dynamically according to the modulation index region of the modulation signals, to achieve the optimal harmonic characteristic in the whole modulation index region and maintain the switching loss. The number of on-state submodules(SMs) can be calculated by CDOSFOPWM, and the selection of SMs is performed by a reducing switching frequency voltage balancing algorithm. Finally, the proposed method is verified by simulation and experimental results. | Fayun ZHOU Qianming XU An LUO Zhixing HE Yan LI Ning XIE Yichao WANG | 2018 | Journal of Modern Power Systems and Clean Energy2018，6，6： | 5 |
| 19 | FPGA-based high resolution DPWM control circuit显示文摘Two improved structures of high resolution digital pulse width modulator(DPWM) control circuit are proposed. Embedded digital clock manager(DCM) blocks and digital programmable delay circuits are employed as the basic resources to construct the field-programmable gate array(FPGA)-based DPWM implementations. Detailed schemes are illustrated and the circuits have been successfully implemented on the Artix-7 FPGA device developed by Xilinx. Experimental results show that when the basic clock operates at the frequency of 200 MHz, the resolutions of the two approaches can reach 625 ps and 500 ps, respectively. Besides,the presented schemes possess other merits including flexible resolution, strong versatility and relatively good stability. | SONG Hu JIANG Naiti HU Shanshan LI Hongtao | 2018 | Journal of Systems Engineering and Electronics2018，29，6： | 5 |
| 20 | 基于PFGA的步进电机PWM发生器设计显示文摘分析并设计了一种脉冲宽度调制(PWM)占空比序列实现步进电机正弦波电流驱动的方法。根据PWM基本原理和步进电机正弦波细分驱动的模式,对PWM计算公式进行了推导,得到了两种不同的计算方法,并得出占空比数据,二进制整数化后得到适合于二进制数字系统的整数化占空比数据序列。同时在Matlab中对PWM驱动方式进行建模、仿真、分析,得到二进制整数化占空比数据序列。对计算、仿真两种结果进行了比较,一致性很好。同时在现场可编程门阵列(FPGA)中设计了占空比序列PWM发生器,利用直接数字频率合成(DDS)选择不同频率的方波,实现步进电机细分数量的任意可调。 | 姜圣广 张卫东 | 2014 | 电气传动2014，44，2： | 4 |
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