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1Indo-Western Pacific Ocean Capacitor and Coherent Climate Anomalies in Post-ENSO Summer: A Review显示文摘ENSO induces coherent climate anomalies over the Indo-western Pacific, but these anomalies outlast SST anomalies of the equatorial Pacific by a season, with major effects on the Asian summer monsoon. This review provides historical accounts of major milestones and synthesizes recent advances in the endeavor to understand summer variability over the Indo-Northwest Pacific region. Specifically, a large-scale anomalous anticyclone(AAC) is a recurrent pattern in post-El Ni ?no summers, spanning the tropical Northwest Pacific and North Indian oceans. Regarding the ocean memory that anchors the summer AAC, competing hypotheses emphasize either SST cooling in the easterly trade wind regime of the Northwest Pacific or SST warming in the westerly monsoon regime of the North Indian Ocean. Our synthesis reveals a coupled ocean–atmosphere mode that builds on both mechanisms in a two-stage evolution. In spring, when the northeast trades prevail, the AAC and Northwest Pacific cooling are coupled via wind–evaporation–SST feedback. The Northwest Pacific cooling persists to trigger a summer feedback that arises from the interaction of the AAC and North Indian Ocean warming, enabled by the westerly monsoon wind regime. This Indo-western Pacific ocean capacitor(IPOC) effect explains why El Ni ?no stages its last act over the monsoonal Indo-Northwest Pacific and casts the Indian Ocean warming and AAC in leading roles. The IPOC displays interdecadal modulations by the ENSO variance cycle, significantly correlated with ENSO at the turn of the 20 th century and after the 1970 s, but not in between. Outstanding issues, including future climate projections, are also discussed.Shang-Ping XIE Yu KOSAKA Yan DU Kaiming HU Jasti S.CHOWDARY Gang HUANG 2016Advances in Atmospheric Sciences2016,33,4:75
2Recent glacial retreat and its effect on water resources in eastern Xinjiang显示文摘The eastern Xinjiang Basin is desperately short of water. Most rivers in the basin originate in the high eastern Tianshan, which has abundant precipitation and numerous alpine glaciers. Fieldwork conducted on three reference glaciers around Mt. Bogda in 1981 and 2009 suggests that they all strongly melt in summer, a process that has tended to accelerate in recent decades. Based on topographic maps from 1962 and 1972 and 2005/2006 satellite imagery, we investigated 203 glaciers near Mt. Bogda and 75 glaciers near Mt. Harlik. The results show that the surface area of the Mt. Bogda glaciers decreased by 21.6% (0.49% a?1) from 1962 to 2006. This was accompanied by a 181 m decrease in length and a 28% drop in ice volume. In the Mt. Harlik region, areal extent was reduced by 10.5% (0.32% a?1), length by 166 m, and volume by 14% between 1972 and 2005. South-facing glaciers lost more of their area than those that are north facing, yielding an areal loss of 25.3% and 16.9% for southern and northern slopes of Mt. Bogda, respectively, and 12.3% and 6.6% for the comparable slopes of Mt. Harlik. Glaciers smaller than 0.5 km2 in area experienced the strongest retreat, whereas glaciers larger than 2 km2 in area experienced gentle recession but may be the main contributors in the future to river runoff. Glacial ablation in eastern Xinjiang tends to be strong, and the water resources in this region are deteriorating. Also, a heavy reduction in the capacity of the local karez system, as well as a significant change in river runoff, can be related to glacial retreat. Combined, this will adversely affect the downstream city of Urumqi and the Turfan Basin.LI KaiMing LI ZhongQin GAO WenYu WANG Lin 2011Chinese Science Bulletin2011,56,33:23
3A novel cognitive ISAR imaging method with random stepped frequency chirp signal显示文摘The random stepped frequency chirp signal(RSFCS)has better performance in anti-jamming than that of conventional stepped frequency chirp signal(SFCS).In combination with the theory of compressing sensing(CS),a novel ISAR imaging method is proposed based on RSFCS,in which the high resolution range profile(HRRP)is reconstructed by using the conventional OMP algorithm,whereas the cognitive approach is introduced to further reduce the number of sub-pulse in RSFCS.In the proposed method,via cognizing the characteristics of moving targets,the number of sub-pulse in each burst can be adjusted adaptively.Finally,in the cross-range direction,the accurate reconstruction of ISAR image by using CS theory is implemented,which can effectively accomplish unwrapping.With the proposed method,high quality HRRP and ISAR image can be achieved with fewer sub-pulses of RSFCS and lower burst repetition frequency(BRF).Some simulation results are given to validate the effectiveness and robustness of the proposed algorithm.ZHU Feng ZHANG Qun LUO Ying LI KaiMing GU FuFei 2012Science China(Information Sciences)2012,55,8:13
4Short Texts Classification Through Reference Document Expansion显示文摘With the rapid development of information technology, short texts arising from socialized human interaction are gradually predominant in network information streams. Accelerating demands are requiring the industry to provide more effective classification of the brief texts.However, faced with short text documents, each of which contains only a few words, traditional document classification models run into difficulty. Aggressive documents expansion works remarkably well for many cases but suffers from the assumption of independent, identically distributed observations. We formalize a view of classification using Bayesian decision theory, treat each short text as observations from a probabilistic model, called a statistical language model, and encode classification preferences with a loss function defined by the language models and the external reference document. According to Vapnik's methods of Structural risk minimization(SRM), the optimal classification action is the one that minimizes the structural risk, which provides a result that allows one to trade off errors on the training sample against improved generalization performance. We conduct experiments by using several corpora of microblog-like data, and analyze the experimental results. With respect to established baselines,results of these experiments show that applying our proposed document expansion method produces better chance to achieve the improved classification performance.YANG Zhen FAN Kefeng LAI Yingxu GAO Kaiming WANG Yong 2014Chinese Journal of Electronics2014,23,2:11
5Rapid repair techniques for severely earthquake-damaged circular bridge piers with flexural failure mode显示文摘In this study, three rapid repair techniques are proposed to retrofit circular bridge piers that are severely damaged by the flexural failure mode in major earthquakes. The quasi-static tests on three 1:2.5 scaled circular pier specimens are conducted to evaluate the efficiency of the proposed repair techniques. For the purpose of rapid repair, the repair procedure for all the specimens is conducted within four days, and the behavior of the repaired specimens is evaluated and compared with the original ones. A finite element model is developed to predict the cyclic behavior of the repaired specimens and the numerical results are compared with the test data. It is found that all the repaired specimens exhibit similar or larger lateral strength and deformation capacity than the original ones. The initial lateral stiffness of all the repaired specimens is lower than that of the original ones, while they show a higher lateral stiffness at the later stage of the test. No noticeable difference is observed for the energy dissipation capacity between the original and repaired pier specimens. It is suggested that the repair technique using the early-strength concrete jacket confined by carbon fiber reinforced polymer(CFRP) sheets can be an optimal method for the rapid repair of severely earthquake-damaged circular bridge piers with flexural failure mode.Sun Zhiguo Li Hongnan Bi Kaiming Si Bingjun Wang Dongsheng 2017Earthquake Engineering and Engineering Vibration2017,16,2:8
6Significantly improved corrosion resistance of Mg-15Gd-2Zn-0.39Zr alloys: Effect of heat-treatment显示文摘The effects of heat-treatment on corrosion behavior of Mg-15Gd-2Zn-0.39Zr alloys were investigated through microstructure characterization, corrosion tests, and scanning Kelvin probe force microscope(SKPFM) analysis. In long-term corrosion experiments, the corrosion rates of Mg-Gd-Zn-Zr alloys were mainly determined by the effects of micro-galvanic corrosion. During heat-treatment, the β-(Mg,Zn)3Gd eutectic phase in as-cast alloys transformed into a long-period stacking ordered(LPSO) phase, coupled with the precipitation of small precipitates. As heat-treatment proceeded, the local potential and the volume fraction of the LPSO phases reduced gradually compared with the eutectic phase, which resulted in a remarkable decrease of the micro-galvanic effect between the second phase and Mg matrix. As a result, the corrosion resistance of heat-treated alloys improved significantly.Jing Liu Lixin Yang Chunyan Zhang Bo Zhang Tao Zhang Yang Li Kaiming Wu Fuhui Wang 2019Journal of Materials Science & Technology2019,35,8:8
7Diurnal variations of the planetary boundary layer height estimated from intensive radiosonde observations over Yichang, China显示文摘By using the eight-times-daily sampling data from an intensive radiosonde observation campaign at Yichang(111°18′E,30°42′N),China in August 2006 and January 2007,the diurnal variation of the planetary boundary layer height determined by using a bulk Richardson(Ri)number approach,was studied in this paper.It was found that the boundary layer heights in both summer and winter months showed diurnal changes and the daily cycle was deeper in summer,which agreed well with the previous studies;the monthly averaged height was 103–1112 m and 89–450 m in summer and winter,respectively;the morning rise began at 0700 LT/1000 LT in summer/winter and the evening transition occurred at 1900 LT in both seasons;the maximum height occurred in the afternoon for most cases,except some peaks found in the winter night;the surface temperature and relative humidity dominated the variations of summer height,while the diurnal variation shown in January 2007 might have some connections with the dynamical processes in the lower troposphere,besides the surface effects.ZHANG YeHui ZHANG ShaoDong HUANG ChunMing HUANG KaiMing GONG Yun GAN Quan 2014Science China(Technological Sciences)2014,57,11:7
8Variations in the equilibrium line altitude of Urumqi Glacier No.1,Tianshan Mountains,over the past 50 years显示文摘The glacier ELA is one of the important parameters reflecting climate change.Based on observations of the equilibrium line altitude(ELA) of Urumqi Glacier No.1 in the Tianshan Mountains,we established a statistical model between ELA and its major influencing factors,warm season air temperature(air temperature averages for May,June,July and August) and annual precipitation.Result showed that,warm season air temperature was the leading climatic factor influencing ELA variations.The glacier ELA ascends(descends) 61.7 m when warm season air temperature increases(decreases) by 1°C,and ascends(descends) 13.1 m when cold season precipitation decreases(increases) by 10%.In the period 1959-2008,the glacier ELA showed a general increasing trend,ascending108 m and reaching its highest altitude in 2008 at 4168 m a.s.l.,close to the glacier summit.If future climate is similar to that in the past 50 years,the ELA of Urumqi Glacier No.1 will still ascend with a speed of 2.16 m/a.However,If future climate is similar to that in the period 2000-2008,the ELA will still ascend with a speed of 6.5 m/a before it is stable.As a result of ELA variation,the accumulation area ratio(AAR) of the glacier showed a decreasing trend during the past 50 years.DONG ZhiWen QIN DaHe REN JiaWen LI KaiMing LI ZhongQin 2012Chinese Science Bulletin2012,57,36:7
9Simulation of multi-support depth-varying earthquake ground motions within heterogeneous onshore and offshore sites显示文摘This paper presents a novel approach to model and simulate the multi-support depth-varying seismic motions(MDSMs) within heterogeneous offshore and onshore sites.Based on 1 D wave propagation theory,the three-dimensional ground motion transfer functions on the surface or within an offshore or onshore site are derived by considering the effects of seawater and porous soils on the propagation of seismic P waves.Moreover,the depth-varying and spatial variation properties of seismic ground motions are considered in the ground motion simulation.Using the obtained transfer functions at any locations within a site,the offshore or onshore depth-varying seismic motions are stochastically simulated based on the spectral representation method(SRM).The traditional approaches for simulating spatially varying ground motions are improved and extended to generate MDSMs within multiple offshore and onshore sites.The simulation results show that the PSD functions and coherency losses of the generated MDSMs are compatible with respective target values,which fully validates the effectiveness of the proposed simulation method.The synthesized MDSMs can provide strong support for the precise seismic response prediction and performance-based design of both offshore and onshore large-span engineering structures.Li Chao Li Hongnan Hao Hong Bi Kaiming Tian Li 2018Earthquake Engineering and Engineering Vibration2018,17,3:6
10Rapamycin promotes Schwann cell migration and nerve growth factor secretion显示文摘Rapamycin, similar to FK506, can promote neural regeneration in vitro. We assumed that the mechanisms of action of rapamycin and FK506 in promoting peripheral nerve regeneration were similar. This study compared the effects of different concentrations of rapamycin and FK506 on Sc hwann cells and investigated effects and mechanisms of rapamycin on improving peripheral nerve regeneration. Results demonstrated that the lowest rapamycin concentration(1.53 nmol/L) more significantly promoted Schwann cell migration than the highest FK506 concentration(100 μmol/L). Rapamycin promoted the secretion of nerve growth factors and upregulated growth-associated protein 43 expression in Schwann cells, but did not significantly affect Schwann cell proliferation. Therefore, rapamycin has potential application in peripheral nerve regeneration therapy.Fang Liu Haiwei Zhang Kaiming Zhang Xinyu Wang Shipu Li Yixia Yin 2014Neural Regeneration Research2014,9,6:6
11Deep Model Compression for Mobile Platforms:A Survey显示文摘Despite the rapid development of mobile and embedded hardware, directly executing computationexpensive and storage-intensive deep learning algorithms on these devices’ local side remains constrained for sensory data analysis. In this paper, we first summarize the layer compression techniques for the state-of-theart deep learning model from three categories: weight factorization and pruning, convolution decomposition, and special layer architecture designing. For each category of layer compression techniques, we quantify their storage and computation tunable by layer compression techniques and discuss their practical challenges and possible improvements. Then, we implement Android projects using TensorFlow Mobile to test these 10 compression methods and compare their practical performances in terms of accuracy, parameter size, intermediate feature size,computation, processing latency, and energy consumption. To further discuss their advantages and bottlenecks,we test their performance over four standard recognition tasks on six resource-constrained Android smartphones.Finally, we survey two types of run-time Neural Network(NN) compression techniques which are orthogonal with the layer compression techniques, run-time resource management and cost optimization with special NN architecture,which are orthogonal with the layer compression techniques.Kaiming Nan Sicong Liu Junzhao Du Hui Liu 2019Tsinghua Science and Technology2019,24,6:6
12Simulation of the equatorial quasi-biennial oscillation based on the parameterization of continuously spectral gravity waves显示文摘On the basis of previous parameterization schemes, considering both the wave breaking and absorbed at critical level, a parameterization with a continuous spectrum of gravity waves is realized by introducing a momentum flux density function for the wave spectrum, and then the parameterization scheme of the gravity waves is improved. Choosing parameter values of the background atmosphere and waves based on the observations, a more realistic equatorial quasi-biennial oscillation (QBO) driven by the incorporated drag from the planetary and gravity waves can be simulated. The numerical results indicate that the forcing magnitude of the planetary and gravity waves varies with the wind field, and in some phases of the QBO, the contribution of the gravity waves is comparable with that of the planetary waves. After the QBO is steadily formed, its amplitude and period and wind configuration are relevant to the effect of vertical diffusion and the momentum flux distribution with spectrum, however, independent of the initial background wind field. Moreover, for any given nonzero initial background wind, a steady QBO can be finally generated due to the incorporated drag from the planetary and gravity waves.HUANG KaiMing ZHANG ShaoDong ,YI Fan CHEN ZeYu 2009Chinese Science Bulletin2009,54,2:6
13Direct growth of ordered N-doped carbon nanotube arrays on carbon fiber cloth as a free-standing and binder-free air electrode for flexible quasi-solid-state rechargeable Zn-Air batteries显示文摘The development of an air electrode that is flexible in physical property and highly active and durable at different geometric status for both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is of crucial importance for the rational design of flexible rechargeable Zn-air batteries(ZABs).Considering their good elasticity,high conductivity,and superior thermal and chemical stability,carbon nanotubes have been widely used as a catalyst support in various electrocatalysts,while oxide or metal nanoparticles have been frequently deposited on the carbon nanotube substrate to perform as the active materials.Considering the poor contact between active materials and carbon nanotubes may introduce a challenge for long-term operating stability,in particular in flexible devices,pure carbon electrocatalyst is highly appreciated.Herein,a free-standing air electrode with cobalt nanoparticles encapsulated N-codoped carbon nanotube arrays uniformly grown on the surface of carbon fiber cloth is developed by a two-step in situ growth method.Such a carbon-based electrode shows outstanding activity for both ORR and OER.The flexible ZAB with such air electrode shows superior flexibility and stability working under extreme bending conditions.Moreover,the polarization and round-trip efficiency for the flexible battery is 0.67 V and 64.4%at 2 mA/cm2,respectively,even after being operated for 30 hours.This study provides a feasible way to design all carbon-based free-standing and flexible electrode and enlightens the electrode design for flexible energy conversion/storage devices.Qian Lu Xiaohong Zou Kaiming Liao Ran Ran Wei Zhou Meng Ni Zongping Shao 2020Carbon Energy2020,2,3:6
14Climatology of global gravity wave activity and dissipation revealed by SABER/TIMED temperature observations显示文摘Gravity wave activity and dissipation in the height range from the low stratosphere to the low thermosphere(25–115 km)covering latitudes between 50°S and 50°N are statistically studied by using 9-year(January 22,2002–December 31,2010)SABER/TIMED temperature data.We propose a method to extract realistic gravity wave fluctuations from the temperature profiles and treat square temperature fluctuations as GW activity.Overall,the gravity wave activity generally increases with height.Near the equator(0°–10°),the gravity wave activity shows a quasi-biennial variation in the stratosphere(below 40 km)while from 20°to 30°,it exhibits an annual variation below 40 km;in low latitudes(0°–30°)between the upper stratosphere and the low thermosphere(40–115 km),the gravity wave activity shows a semi-annual variation.In middle latitudes(40°–50°),the gravity wave activity has a clear annual variation below 85 km.In addition,we observe a four-monthly variation with peaks occurring usually in April,August,December in the northern hemisphere and in February,June,October in the southern hemisphere,respectively,above 85 km in middle latitudes,which has been seldom reported in gravity wave activity.In order to study the dissipation of gravity wave propagation,we calculate the gravity wave dissipation ratio,which is defined as the ratio of the gravity wave growth scale height to the atmosphere density scale height.The height variation of the dissipation ratio indicates that strong gravity wave dissipation mainly concentrates in the three height regions:the stratosphere(30–60 km),the mesopause(around 85 km)and the low thermosphere(above 100 km).Besides,gravity wave energy enhancement can be also observed in the background atmosphere.SHUAI Jing ZHANG ShaoDong HUANG ChunMing YI Fan HUANG KaiMing GAN Quan GONG Yun 2014Science China(Technological Sciences)2014,57,5:5
15An Introduction to the Integrated Climate Model of the Center for Monsoon System Research and Its Simulated Influence of El Ni?no on East Asian–Western North Pacific Climate显示文摘This study introduces a new global climate model—the Integrated Climate Model(ICM)—developed for the seasonal prediction of East Asian–western North Pacific(EA–WNP) climate by the Center for Monsoon System Research at the Institute of Atmospheric Physics(CMSR, IAP), Chinese Academy of Sciences. ICM integrates ECHAM5 and NEMO2.3 as its atmospheric and oceanic components, respectively, using OASIS3 as the coupler. The simulation skill of ICM is evaluated here, including the simulated climatology, interannual variation, and the influence of El Nińo as one of the most important factors on EA–WNP climate. ICM successfully reproduces the distribution of sea surface temperature(SST) and precipitation without climate shift, the seasonal cycle of equatorial Pacific SST, and the precipitation and circulation of East Asian summer monsoon. The most prominent biases of ICM are the excessive cold tongue and unrealistic westward phase propagation of equatorial Pacific SST. The main interannual variation of the tropical Pacific SST and EA–WNP climate—El Nińo and the East Asia–Pacific Pattern—are also well simulated in ICM, with realistic spatial pattern and period. The simulated El Nińo has significant impact on EA–WNP climate, as in other models. The assessment shows ICM should be a reliable model for the seasonal prediction of EA–WNP climate.HUANG Ping WANG Pengfei HU Kaiming HUANG Gang ZHANG Zhihua LIU Yong YAN Bangliang 2014Advances in Atmospheric Sciences2014,31,5:5
16Hydrophilic/underwater superoleophobic graphene oxide membrane intercalated by TiO2 nanotubes for oil/water separation显示文摘Zhichao Wu Chang Zhang Kaiming Peng Qiaoying Wang Zhiwei Wang 2018Frontiers of Environmental Science & Engineering2018,12,3:5
17A fiber optoacoustic guide with augmented reality for precision breastconserving surgery显示文摘Lumpectomy,also called breast-conserving surgery,has become the standard surgical treatment for early-stage breast cancer.However,accurately locating the tumor during a lumpectomy,especially when the lesion is small and nonpalpable,is a challenge.Such difficulty can lead to either incomplete tumor removal or prolonged surgical time,which result in high re-operation rates(~25%)and increased surgical costs.Here,we report a fiber optoacoustic guide(FOG)with augmented reality(AR)for sub-millimeter tumor localization and intuitive surgical guidance with minimal interference.The FOG is preoperatively implanted in the tumor.Under external pulsed light excitation,the FOG omnidirectionally broadcasts acoustic waves through the optoacoustic effect by a specially designed nano-composite layer at its tip.By capturing the acoustic wave,three ultrasound sensors on the breast skin triangulate the FOG tip’s position with 0.25-mm accuracy.An AR system with a tablet measures the coordinates of the ultrasound sensors and transforms the FOG tip’s position into visual feedback with<1-mm accuracy,thus aiding surgeons in directly visualizing the tumor location and performing fast and accurate tumor removal.We further show the use of a head-mounted display to visualize the same information in the surgeons’first-person view and achieve hands-free guidance.Towards clinical application,a surgeon successfully deployed the FOG to excise a“pseudo tumor”in a female human cadaver.With the high-accuracy tumor localization by FOG and the intuitive surgical guidance by AR,the surgeon performed accurate and fast tumor removal,which will significantly reduce re-operation rates and shorten the surgery time.Lu Lan Yan Xia Rui Li Kaiming Liu Jieying Mai Jennifer Anne Medley Samilia Obeng-Gyasi Linda K.Han Pu Wang Ji-Xin Cheng 2018Light(Science & Applications)2018,7,1:4
18Effects of Continuous Cropping of Panax notoginseng on the Properties of Rhizosphere Soil显示文摘[Objective] This experiment aimed to investigate the effects of continuous cropping of Panax notoginseng on the properties of rhizosphere soil. [Method] A total of 12 rhizospheres oil samples were collected in the fields continuously cropped with P. notoginseng for different years and the soil properties including pH value, contents of available N, available K, available P,total N, total K, total P and organic matter were determined. [Result] With the increase in the number of years of continuous cropping, seven soli indices: soil pH value, organic matter content, total N, total P, total K, available P and available K gradually increased, while available N showed a gradual downward trend. The contents of organic matter content, total N, total P, total K,available P, available K and available N after three years of continuous cropping were increased by 74.93%, 65.85%, 123.82%,18.78%, 341.67%, 120.16% and-32.16%, respectively, indicating that continuous cropping of P. notoginseng resulted in nutrient enrichment in rhizosphere soils. The pH value and available N in IBC(soil inside the border check) and UBC(soil under the border check) were higher than that in BBC(soil beside the border check), suggesting that the soil was gradually alkalized due to the continuous cropping of P. notoginseng. [Conclusion] These results suggest that pH change and nutrient imbalance may be the obstacles to the continuous cropping of P. notoginseng.Kaiming LI Meixiang LIU Qianhui SUN Zilong ZHANG 2017Agricultural Science & Technology2017,18,4:4
19Application of waste frying oils in the biosynthesis of biodemulsifier by a demulsifying strain Alcaligenes sp.S-XJ-1显示文摘Exploration of biodemulsifiers has become a new research aspect.Using waste frying oils(WFOs) as carbon source to synthesize biodemulsifiers has a potential prospect to decrease production cost and to improve the application of biodemulsifiers in the oilfield.In this study,a demulsifying strain,Alcaligenes sp.S-XJ-1,was investigated to synthesize a biodemulsifier using waste frying oils as carbon source.It was found that the increase of initial pH of culture medium could increase the biodemulsifier yield but decrease the demulsification ratio compared to that using paraffin as carbon source.In addition,a biodemulsifier produced by waste frying oils and paraffin as mixed carbon source had a lower demulsification capability compared with that produced by paraffin or waste frying oil as sole carbon source.Fed-batch fermentation of biodemulsifier using waste frying oils as supplementary carbon source was found to be a suitable method.Mechanism of waste frying oils utilization was studied by using tripalmitin,olein and tristearin as sole carbon sources to synthesize biodemulsifier.The results showed saturated long-chain fatty acid was diffcult for S-XJ-1 to utilize but could effectively enhance the demulsification ability of the produced biodemulsifier.Moreover,FT-IR result showed that the demulsification capability of biodemulsifiers was associated with the content of C=O group and nitrogen element.Jia Liu Kaiming Peng Xiangfeng Huang Lijun Lu Hang Cheng Dianhai Yang Qi Zhou Huiping Deng 2011Journal of Environmental Sciences2011,23,6:4
20Novel PAPR Reduction Scheme Based on Continuous Nonlinear Piecewise Companding Transform for OFDM Systems显示文摘In this paper,a novel efficient continuous piecewise nonlinear companding scheme is proposed for reducing the peak-to-average power ratio(PAPR)of orthogonal frequency division multiplexing(OFDM)systems.In the proposed companding transform,signal samples with large amplitudes is clipped for peak power reduction,and the signal samples with medium amplitudes is nonlinear transformed with power compensation.While the signal samples with small amplitudes remain unchanged.The whole companding function is continuous and smooth in the range of positive numbers,which is beneficial for guaranteeing the bit error rate(BER)and power spectral density(PSD)performance.This scheme can achieve a significant reduction in PAPR.And at the same time,it cause little increment in BER and PSD performance.Simulation results indicate the superiority of the proposed scheme over existing companding schemes.Zhitong Xing Kaiming Liu Kaiyuan Huang Bihua Tang Yuanan Liu 2020China Communications2020,17,9:4
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