期刊文献+
共找到418篇文章
< 1 2 21 >
每页显示 20 50 100
Electroacupuncture with different waveforms for primary dysmenorrhea:A randomized controlled trial
1
作者 Xiaona Wu Jingxue Yuan +5 位作者 Jinxia Ni Xiuli Ma Ziniu Zhang Yini Hua Juwei Dong Bob Peng Wang 《Journal of Traditional Chinese Medical Sciences》 CAS 2024年第3期357-362,共6页
Objective:To observe and compare the clinical effects of different electroacupuncture waveforms on primary dysmenorrhea.Methods: This was a prospective,randomized,three-group,parallel-controlled trial.Participants wit... Objective:To observe and compare the clinical effects of different electroacupuncture waveforms on primary dysmenorrhea.Methods: This was a prospective,randomized,three-group,parallel-controlled trial.Participants with primary dysmenorrhea were randomly divided into dense-sparse wave,continuous wave,and discontinuous wave groups in a 1:1:1 ratio.Two lateral Ciliao(BL 32)points were used.All three groups started treatment 3–5 days before menstruation,once a day for six sessions per course of treatment,one course of treatment per menstrual cycle,and three menstrual cycles.The primary outcome measure was the proportion with an average visual analog scale(VAS)score reduction of≥50%from baseline for dysmenorrhea in the third menstrual cycle during treatment.The secondary outcome measures included changes in dysmenorrhea VAS scores,Cox Menstrual Symptom Scale scores and the proportion of patients taking analgesic drugs.Results: The proportion of cases where the average VAS score for dysmenorrhea decreased by≥50%from baseline in the third menstrual cycle was not statistically significant(P>.05).Precisely 30 min after acupuncture and regarding immediate analgesia on the most severe day of dysmenorrhea,there was a statistically significant difference in the dense-sparse wave group compared with the other two groups during the third menstrual cycle(P<.05).Additionally,there was a statistically significant difference between the dense-sparse wave and discontinuous wave groups 24 h after acupuncture(P<.05).Conclusions: Waveform electroacupuncture can alleviate primary dysmenorrhea and its related symptoms in patients.The three groups showed similar results in terms of short-and long-term analgesic efficacy and a reduction in the number of patients taking analgesic drugs.Regarding achieving immediate analgesia,the dense-sparse wave group was slightly better than the other two groups. 展开更多
关键词 waveforms Ciliao(BL 32) ELECTROACUPUNCTURE Primary dysmenorrhea Randomized controlled trial Dense-sparse waves Continuous waves Discontinuous waves
下载PDF
A Comprehensive Survey of Candidate Waveforms for 5G, beyond 5G and 6G Wireless Communication Systems
2
作者 Bakhit Amine Adoum Kalsouabe Zoukalne +3 位作者 Mahamat Saleh Idriss Ali Mahmoud Ali Amir Moungache Mahamoud Youssouf Khayal 《Open Journal of Applied Sciences》 CAS 2023年第1期136-161,共26页
The evolution of global mobile data over the past decades in broadcasting, Internet of Things (IoT), education, healthcare, commerce, and energy has put strong pressure on 3G/4G mobile networks to improve their servic... The evolution of global mobile data over the past decades in broadcasting, Internet of Things (IoT), education, healthcare, commerce, and energy has put strong pressure on 3G/4G mobile networks to improve their service offerings. These generations of mobile networks were initially invented to meet the requirements of the above-mentioned applications. However, as the requirements in these applications continue to increase, new mobile technologies such as 5G (fifth generation), 5G and beyond (B5G, beyond fifth generation), and 6G (sixth generation) are still progressing and being experimented. These networks are very heterogeneous generations of mobile networks that will have to offer very high throughput per user, good energy efficiency, better traffic capacity per area, improved spectral efficiency, very low latency, and high mobility. To meet these requirements, the radio interface of future mobile networks will have to be flexible and rationalized the available frequency resources. Therefore, new modulation methods, access techniques and waveforms capable of supporting these technological changes are proposed. This review presents brief descriptions of the types of 5G, B5G, and 6G waveforms. The 5G consists of OFDM including its transmission techniques: generalized frequency division multiplexing (GFDM), filter bank based multi-carrier (FBMC), universal filtered multi-carrier (UFMC), and index modulation (IM). Meanwhile, the 6G covers orthogonal time frequency space (OTFS), orthogonal chirp division multiplexing (OCDM) and orthogonal time sequence multiplexing (OTSM). The networks’ potentialities, advantages, disadvantages, and future directions are outlined. 展开更多
关键词 MODULATION 5G B5G 6G waveforms
下载PDF
AUTOFOCUSING OF SYNTHETIC HRR RADAR USING STEPPED FREQUENCY WAVEFORMS
3
作者 朱岱寅 朱兆达 戴明桢 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1999年第1期14-20,共7页
Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtai... Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtain the HRR profile of a target. For moving targets which are of great importance in practical radar usage, autofocusing,i.e. phase correction, is a necessary and critical step of the synthetic HRR processing. The purpose of autofocusing is to remove the radial motion effect of the target from radar echoes, and only reserve the stepped frequency effect which is the basis of synthetic HRR capability. We investigate two autofocusing approaches for synthetic HRR radars using stepped frequency waveform in this paper. The first is motion fitting method. This method depends on a certain parametric model, and is computationally expensive. Then we propose the iterative dominant scatterer method. It is robust, non parametric and simple in computation in comparison with the motion fitting method. Experimental results based on data acquired by using a metallised scale model B 52 in a microwave anechoic chamber reveal the validity and effectiveness of the method. 展开更多
关键词 radars high range resolution autofocusing approaches stepped frequency waveforms
下载PDF
A combined denoising method of empirical mode decomposition and singular spectrum analysis applied to Jason altimeter waveforms: A case of the Caspian Sea 被引量:1
4
作者 Wenguan Jiang Wei You 《Geodesy and Geodynamics》 CSCD 2022年第4期327-342,共16页
During the satellite pulse propagation and reception, the altimeter waveform is inevitably affected by noise. To reduce the noise level in Jason altimeter waveforms, we used singular spectrum analysis(SSA),empirical m... During the satellite pulse propagation and reception, the altimeter waveform is inevitably affected by noise. To reduce the noise level in Jason altimeter waveforms, we used singular spectrum analysis(SSA),empirical mode decomposition(EMD), and the combination of SSA and EMD to obtain the denoised waveforms. The advantages of the combined method were verified and the accuracy of the mean sea surface height(MSSH) model was improved. Comparing the denoising effect of the three methods, the results show that the signal-to-noise ratio(SNR), correlation coefficient and root-mean-square error are effectively improved by the combination of SSA and EMD. The sea surface heights(SSHs) were remeasured with a 50% threshold retracker of denoised waveforms, and the MSSH model of the Caspian Sea with a grid of 1’× 1’was established from the retracked SSHs of Jason-1/2/3. Taking the mean value of the four models as a control, it is found that the model calculated by the combined denoising method has the highest accuracy. This indicates that using the combined denoising method to reduce the noise level is beneficial to improve the accuracy of the MSSH model. 展开更多
关键词 Altimetry waveforms Jason-1/2/3 Combined method Waveform retracking Mean sea surface height
下载PDF
Construction of Zero Autocorrelation Stochastic Waveforms
5
作者 Somantika Datta 《Advances in Pure Mathematics》 2012年第6期428-440,共13页
Stochastic waveforms are constructed whose expected autocorrelation can be made arbitrarily small outside the origin. These waveforms are unimodular and complex-valued. Waveforms with such spike like autocorrelation a... Stochastic waveforms are constructed whose expected autocorrelation can be made arbitrarily small outside the origin. These waveforms are unimodular and complex-valued. Waveforms with such spike like autocorrelation are desirable in waveform design and are particularly useful in areas of radar and communications. Both discrete and continuous waveforms with low expected autocorrelation are constructed. Further, in the discrete case, frames for Cd are constructed from these waveforms and the frame properties of such frames are studied. 展开更多
关键词 AUTOCORRELATION FRAMES STOCHASTIC waveforms
下载PDF
Construction of Energy-Optimal Smooth Monophasic Defibrillation Pulse Waveforms Using Cardiomyocyte Membrane Model
6
作者 Vyacheslav A. Vostrikov Boris B. Gorbunov Sergey V. Selishchev 《Journal of Biomedical Science and Engineering》 2015年第9期625-631,共7页
The goal is to help create smooth energy-optimal monophasic pulse waveforms for defibrillation using the Luo-Rudy cardiomyocyte membrane computer model. The waveforms were described with the help of the piecewise line... The goal is to help create smooth energy-optimal monophasic pulse waveforms for defibrillation using the Luo-Rudy cardiomyocyte membrane computer model. The waveforms were described with the help of the piecewise linear function. Each line segment provides a transition from one present level of the transmembrane potential to the next with a minimal energy value. The duration of the last segment was defined as a minimum duration at which an action potential occurs. Monophasic waveforms of segments 3, 10 and 29 were built using different increments of the transmembrane potential. The pulse energy efficiency was evaluated according to their threshold energy ratios in mA2·ms/cm4. There was virtually no difference between the threshold energy ratios of the three waveforms constructed and those of the previously studied energy-optimal half- sine waveform: 241 - 242 and 243 mA2·ms/cm4. The pulse waveform constructed is characterized by a low rise and fall as the duration of the rise is ~1.5 times longer than that of the fall. Conclusion: Energy-optimal smooth monophasic pulse waveforms have the same threshold energy ratio as the optimal half-sine one which was studied before. The latter is equivalent to the first phase of biphasic quasisinusoidal Gurvich-Venin pulse which has been used in Russia since 1972. Thus, the use of the Luo-Rudy cardiomyocyte membrane model appears to offer no possibilities for a substantial increase in the energy efficiency (threshold energy ratio reduction) of the classical monophasic defibrillation pulse waveforms. 展开更多
关键词 Energy-Optimal DEFIBRILLATION PULSE Waveform MONOPHASIC DEFIBRILLATION PULSE waveforms Modeling Energy Ratio CARDIOMYOCYTE TRANSMEMBRANE POTENTIAL Action POTENTIAL
下载PDF
Performances of Micropower UWB Radar Using Orthogonal Waveforms
7
作者 Laila Sakkila Atika Rivenq +2 位作者 Charles Tatkeu Yassin Elhillali Jean-Pierre Ghys 《Wireless Engineering and Technology》 2014年第3期74-87,共14页
Radars and their applications were, for a long time, reserved to national defense, air security or weather service domains. For a few years, with the emergence of new technologies, radar applications have been develop... Radars and their applications were, for a long time, reserved to national defense, air security or weather service domains. For a few years, with the emergence of new technologies, radar applications have been developed and have become known in the civil domain. In particular, the arrival of UWB—Ultra-Wideband technology allows the design of compact and low-cost radars with multiple fields of application. In this paper, we focus on road applications, such as driving assistance with the objective of increasing safety and reducing accidents. In classical UWB radar systems, Gaussian and monocycle pulses are commonly used. In previous works, original waveforms based on orthogonal functions (Hermite and Gegenbauer) were proposed. These provide a good spatial resolution, suitable for radar detection. Another advantage of these waveforms is their multiple access capability, due to their orthogonality. The aim of the study presented in this article is to compare simulation and experimental results obtained, especially for short-range anticollision radar application, using these waveforms in one part and Gaussian and monocycle pulses in the other part. The originality of this paper relies on the new approach. Indeed, this comparison study using these waveforms has never been done before. Finally, some examples of real experiments in a real road environment with different waveforms are presented and analysed. 展开更多
关键词 UWB Technology ORTHOGONAL waveforms COMPARISON RADAR Applications
下载PDF
Upper-mantle velocity structures beneath the Tibetan Plateau and surrounding areas inferred from triplicated P waveforms 被引量:10
8
作者 RiSheng Chu LuPei Zhu ZhiFeng Ding 《Earth and Planetary Physics》 CSCD 2019年第5期444-458,共15页
P-wave waveforms in the distance range between 12°and 30°were analyzed to investigate upper-mantle P velocity structures beneath the Tibetan Plateau and surrounding areas.The waveform data from 504 earthquak... P-wave waveforms in the distance range between 12°and 30°were analyzed to investigate upper-mantle P velocity structures beneath the Tibetan Plateau and surrounding areas.The waveform data from 504 earthquakes with magnitudes larger than 5.0 between 1990 and 2005 that occurred within 30°from the center of the Plateau were modelled.We divided the study area into 6 regions and modeled upper-mantle-distance P waveforms with turning points beneath each region separately.The results show that the uppermantle P-wave velocity structures beneath India,the Himalayas,and the Lhasa Terrane are similar and contain a high-velocity lid about 250 km thick.The upper-mantle velocities down to 200 km beneath the Qiangtang Terrane,the Tarim Basin,and especially the Songpan-GarzêTerrane are lower than those in the south.The 410-km discontinuity beneath these two terranes is elevated by about 20 km.Highvelocity anomalies are found in the transition zone below 500 km under the Lhasa and Qiangtang Terranes.The results suggest that the Tibetan Plateau was generated by thrusting of the Indian mantle lithosphere under the southern part of Tibet.Portions of the thickened Eurasian mantle lithosphere were delaminated;they are now sitting in the transition zone beneath southern Tibet and atop of the 410-km discontinuity underneath northern Tibet. 展开更多
关键词 TIBETAN Plateau upper MANTLE structure triplication waveform modelling
下载PDF
Effects of loading waveforms on rock damage using particle simulation method 被引量:5
9
作者 XIA Ming GONG Feng-qiang 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第7期1755-1765,共11页
The particle simulation method is used to study the effects of loading waveforms (i.e. square, sinusoidal and triangle waveforms) on rock damage at mesoscopic scale. Then some influencing factors on rock damage at t... The particle simulation method is used to study the effects of loading waveforms (i.e. square, sinusoidal and triangle waveforms) on rock damage at mesoscopic scale. Then some influencing factors on rock damage at the mesoscopic scale, such as loading frequency, stress amplitude, mean stress, confining pressure and loading sequence, are also investigated with sinusoidal waveform in detail. The related numerical results have demonstrated that: 1) the loading waveform has a certain effect on rock failure processes. The square waveform has the most damage within these waveforms, while the triangle waveform has less damage than sinusoidal waveform. In each cycle, the number of microscopic cracks increases in the loading stage, while it keeps nearly constant in the unloading stage. 2) The loading frequency, stress amplitude, mean stress, confining pressure and loading sequence have considerable effects on rock damage subjected to cyclic loading. The higher the loading frequency, stress amplitude and mean stress, the greater the damage the rock accumulated; in contrast, the lower the confining pressure, the greater the damage the rock has accumulated. 3) There is a threshold value of mean stress and stress amplitude, below which no further damage accumulated after the first few cycle loadings. 4) The high-to-low loading sequence has more damage than the low-to-high loading sequence, suggesting that the rock damage is loading-path dependent. 展开更多
关键词 rock damage failure process crack initiation and propagation loading waveform cycle loading particle simulation method
下载PDF
Simutaneous radar imaging and velocity measuring with step frequency waveforms 被引量:4
10
作者 Yuan Haotian Wen Shuliang Cheng Zhen 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第4期741-747,共7页
The principle and method of both radar target imaging and velocity measurement simultaneously based on step frequency waveforms is presented. Velocity compensation is necessary in order to obtain the good High resolut... The principle and method of both radar target imaging and velocity measurement simultaneously based on step frequency waveforms is presented. Velocity compensation is necessary in order to obtain the good High resolution range profile since this waveform is greatly sensitive to the Doppler shift. The velocity measurement performance of the four styles is analyzed with two pulse trains consisted of positive and negative step frequency waveforms. The velocity of targets can be estimated first coarsely by using the pulse trains with positive-positive step frequency combination, and then fine by positive-negative combination. Simulation results indicate that the method can accomplish the accurate estimation of the velocity with efficient computation and good anti-noise performance and obtain the good HRRP simultaneously. 展开更多
关键词 high resolution radar step frequency waveform velocity measuring high resolution range profile.
下载PDF
Inversion of ocean-bottom seismometer(OBS) waveforms for oceanic crust structure: a synthetic study 被引量:2
11
作者 Xueyan Li Yanbin Wang Yongshun John Chen 《Earthquake Science》 CSCD 2016年第4期203-213,共11页
The waveform inversion method is applied-- using synthetic ocean-bottom seismometer (OBS) data--to study oceanic crust structure. A niching genetic algorithm (NGA) is used to implement the inversion for the thickn... The waveform inversion method is applied-- using synthetic ocean-bottom seismometer (OBS) data--to study oceanic crust structure. A niching genetic algorithm (NGA) is used to implement the inversion for the thickness and P-wave velocity of each layer, and to update the model by minimizing the objective function, which consists of the misfit and cross-correlation of observed and synthetic waveforms. The influence of specific NGA method parameters is discussed, and suitable values are presented. The NGA method works well for various observation systems, such as those with irregular and sparse distribu- tion of receivers as well as single receiver systems. A strategy is proposed to accelerate the convergence rate by a factor of five with no increase in computational complex- ity; this is achieved using a first inversion with several generations to impose a restriction on the preset range of each parameter and then conducting a second inversion with the new range. Despite the successes of this method, its usage is limited. A shallow water layer is not favored because the direct wave in water will suppress the useful reflection signals from the crust. A more precise calculation of the air-gun source signal should be considered in order to better simulate waveforms generated in realistic situa- tions; further studies are required to investigate this issue. 展开更多
关键词 Waveform inversion OBS Oceanic crustalstructure Niching genetic algorithm
下载PDF
Effects of output waveforms on penetration for Nd :YAG laser welding 被引量:1
12
作者 王家淳 沈剑韵 王希哲 《China Welding》 EI CAS 2000年第1期67-77,共11页
By using a Nd: YAG laser welding system devised for transmitting continuous, rectangular and pulsed waveforms, comprehensive and deep investigation is focused on the effects of several parameters of rectangular wavefo... By using a Nd: YAG laser welding system devised for transmitting continuous, rectangular and pulsed waveforms, comprehensive and deep investigation is focused on the effects of several parameters of rectangular waveform and pulsed output wave superimposed on a rectangular waveform on the penetration depth of weld. Research results indicate that the average power, duty cycle, frequency and peak power of rectangular wave affect the weld penetration depth to different extent. Results of experiments and analysis also indicate that the pulse delay time, pulse width and the power ratio of pulse to rectangular waveform seriously influence the penetration when the pulsed wave is superimposed on a rectangular waveform. 展开更多
关键词 Nd: YAG laser welding output waveform PENETRATION rectangular waveform pulsed wave
下载PDF
Arbitrary Waveforms Based on Front Panel of Agilent 33250A Function/Arbitrary Waveform Generator 被引量:1
13
作者 GAO Jian XIN Changfan ZHANG Shilong 《Semiconductor Photonics and Technology》 CAS 2010年第2期110-112,120,共4页
Agilent 33200A family of function/arbitrary waveform generators are widely used in labs for creating arbitrary waveforms.Flexible applications of function/arbitrary waveform generator 33250A which is made by Agilent c... Agilent 33200A family of function/arbitrary waveform generators are widely used in labs for creating arbitrary waveforms.Flexible applications of function/arbitrary waveform generator 33250A which is made by Agilent company are expatiated.There are three methods of transferring waveform data to arbitrary waveform generator 33250A,among which,the front panel method can produce a simple interface for arbitrary waveforms and is applicable to the composition of a small amount of linear waveform segment,and the progress of this method is explained in detail.This way is convenient and can be widely used,and it will offer some good guidance in library works. 展开更多
关键词 function/arbitrary waveform generator Agilent 33250A front panel
下载PDF
Study on atomic layer etching of Si in inductively coupled Ar/Cl_2 plasmas driven by tailored bias waveforms 被引量:1
14
作者 麻晓琴 张赛谦 +1 位作者 戴忠玲 王友年 《Plasma Science and Technology》 SCIE EI CAS CSCD 2017年第8期97-108,共12页
Plasma atomic layer etching is proposed to attain layer-by-layer etching, as it has atomic-scale resolution, and can etch monolayer materials. In the etching process, ion energy and angular distributions(IEADs) bomb... Plasma atomic layer etching is proposed to attain layer-by-layer etching, as it has atomic-scale resolution, and can etch monolayer materials. In the etching process, ion energy and angular distributions(IEADs) bombarding the wafer placed on the substrate play a critical role in trench profile evolution, thus importantly flexibly controlling IEADs in the process. Tailored bias voltage waveform is an advisable method to modulate the IEADs effectively, and then improve the trench profile. In this paper, a multi-scale model, coupling the reaction chamber model,sheath model, and trench model, is used to research the effects of bias waveforms on the atomic layer etching of Si in Ar/Cl2 inductively coupled plasmas. Results show that different discharge parameters, such as pressure and radio-frequency power influence the trench evolution progress with bias waveforms synergistically. Tailored bias waveforms can provide nearly monoenergetic ions, thereby obtaining more anisotropic trench profile.??? 展开更多
关键词 inductively etching sheath trench waveform chamber settled figure anisotropic angular
下载PDF
Photonic generation of arbitrary waveforms based on incoherent wavelength-to-time mapping
15
作者 董建绩 罗博文 +1 位作者 于源 张新亮 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第6期538-542,共5页
We demonstrate experimentally a radio frequency arbitrary waveform generator using the incoherent wavelength-to-time mapping technique. The system is implemented by amplitude modulation of a broadband optical resource... We demonstrate experimentally a radio frequency arbitrary waveform generator using the incoherent wavelength-to-time mapping technique. The system is implemented by amplitude modulation of a broadband optical resource whose spectrum is reshaped by a programmable optical pulse shaper and transmitted over a single mode fiber link. The shape of the generated waveform is controlled by the optical pulse shaper, and the fiber link introduces a certain group velocity delay to implement wavelength-to-time mapping. Assisted by the flexible optical pulse shaper, we obtain different shapes of optical waveforms, such as rectangle, triangle, and sawtooth waveforms. Furthermore, we also demonstrate ultra-wideband generation, such as Gaussian monocycle, doublet, and triplet waveforms, using the incoherent technique. 展开更多
关键词 arbitrary waveform generation ULTRA-WIDEBAND wavelength-to-time mapping incoherenttechnique arbitrary waveform generation ULTRA-WIDEBAND wavelength-to-time mapping incoherent technique
下载PDF
A CLASS OF BAND-LIMITED CHIP WAVEFORMS FOR DS-CDMA SYSTEMS
16
作者 Song Rongfang Bi Guangguo Xie Daxiong 《Journal of Electronics(China)》 2007年第1期10-15,共6页
In Direct Sequence Code Division Multiple Access (DS-CDMA) systems,the chip wave-form affects the implementation,system bandwidth,envelope uniformity,eye pattern and Multiple user Access Interference (MAI). In this pa... In Direct Sequence Code Division Multiple Access (DS-CDMA) systems,the chip wave-form affects the implementation,system bandwidth,envelope uniformity,eye pattern and Multiple user Access Interference (MAI). In this paper,based on an elementary density function of a second order polynomial,a class of second order continuity pulses is proposed. From this class of pulses,we can find some members having faster decaying rate,bigger eye opening,more uniform envelope and stronger anti-MAI capability than the Nyquist waveform. The normalized-bandwidth-pulse-shape-factor product,the decaying rate of the tail of the time waveform,the opening of the eye diagram,and the envelope uniformity of the second order continuity pulses are addressed in the paper that provide the basic information for the selection of the chip pulse for CDMA systems. 展开更多
关键词 Chip waveform Direct Sequence Code Division Multiple Access (DS-CDMA) Eye diagram Envelope uniformity
下载PDF
Fault Plane Identification Using Three Components Local Waveforms
17
作者 Bagus Jaya Santosa 《International Journal of Geosciences》 2013年第6期993-1001,共9页
A research has been conducted to estimate earthquake source parameters that occurred on June 3rd, 13th, 18th and 19th, 2008. The data used to determine the parameters of earthquakes source are three components local w... A research has been conducted to estimate earthquake source parameters that occurred on June 3rd, 13th, 18th and 19th, 2008. The data used to determine the parameters of earthquakes source are three components local waveform that are recorded by three MY broadband stations (IPM, KOM and KUM) and PSI, Poseidon. In this research, we report a focal mechanism of events using three components local waveform analysis. The seismogram data are inverted to achieve the earthquake source parameters. Source parameters of earthquakes extracted after the reduction variant of each event are over 56%. To identify the fault plane, the HC-plot method is used. 展开更多
关键词 3 Components LOCAL WAVEFORM EARTHQUAKE SOURCE PARAMETERS
下载PDF
RADAR HRR PROFILING FOR GROUND MOVING TARGET USING PHASE-CODED AND HOPPED-FREQUENCY WAVEFORMS
18
作者 Li Yan Wang Changming 《Journal of Electronics(China)》 2007年第2期187-190,共4页
To obtain the radar High Range Resolution (HRR) profile of the slowly moving ground target in strong clutter background, the Phase-Coded Hopped-Frequency (PCHF) waveform is proposed. By multiple-bursts coherent proces... To obtain the radar High Range Resolution (HRR) profile of the slowly moving ground target in strong clutter background, the Phase-Coded Hopped-Frequency (PCHF) waveform is proposed. By multiple-bursts coherent processing, the HRR profile synthesis, target velocity compensation and clutter compression can be accomplished simultaneously. The new waveform is shown to have good ability to suppress ground clutter and good Electronic Counter-CounterMeasures (ECCM) ability as well. The clutter compression performance of the proposed method is verified by the numerical results. 展开更多
关键词 Radar High Range Resolution (HRR) profile Phase-Coded Hopped-Frequency (PCHF) waveform Clutter compression Ground moving target detection
下载PDF
High Resolution MIMO-HFSWR Radar Using Sparse Frequency Waveforms
19
作者 Guohua WANG Yilong LU 《Wireless Sensor Network》 2009年第3期152-162,共11页
In high frequency surface wave radar (HFSWR) applications, range and azimuth resolutions are usually lim-ited by the bandwidth of waveforms and the physical dimension of the radar aperture, respectively. In this paper... In high frequency surface wave radar (HFSWR) applications, range and azimuth resolutions are usually lim-ited by the bandwidth of waveforms and the physical dimension of the radar aperture, respectively. In this paper, we propose a concept of multiple-input multiple-output (MIMO) HFSWR system with widely sepa-rated antennas transmitting and receiving sparse frequency waveforms. The proposed system can overcome the conventional limitation on resolutions and obtain high resolution capability through this new configura-tion. Ambiguity function (AF) is derived in detail to evaluate the basic resolution performance of this pro-posed system. The advantages of the system of fine resolution and low peak sidelobe level (PSL) are demon-strated by the AF analysis through numerical simulations. The impacts of Doppler effect and the geometry configuration are also studied. 展开更多
关键词 MIMO HFSWR RADAR SPARSE FREQUENCY WAVEFORM
下载PDF
UWB Communication System Based on Bipolar PPM with Orthogonal Waveforms
20
作者 Amel Elabed Fouzia Elbahhar +2 位作者 Yassin Elhillali Atika Rivenq Raja Elassali 《Wireless Engineering and Technology》 2012年第3期181-188,共8页
In many classic Ultra Wide Band communication systems, only Gaussian and monocycle pulses associate to PPM modulation are used. In this paper, an original communication system based on orthogonal functions and the Bip... In many classic Ultra Wide Band communication systems, only Gaussian and monocycle pulses associate to PPM modulation are used. In this paper, an original communication system based on orthogonal functions and the Bipolar PPM modulation is proposed. This system allows good performances in terms of Bit Error Rate (BER) and high data rate. This study concerns new applications, such as Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) communication systems or a wireless link between computers. These applications need high reliability to transmit security-related information and high data rate to exchange multimedia data. With the emergence of the orthogonal wave-forms, the performances of the UWB communication system will be more interesting in terms of BER and data rate. In this paper, two kinds of improvement are proposed. The first improvement permits us to decrease the Bit Error Rate using the original waveforms. The second allows improving the data rate via novel modulation method. The last parameter study, in this paper, concerns the problem of synchronization between the different users. We will study the performances of the proposed system in multiusers environment in synchronous and asynchronous cases. In the first stage, the theoretical and simulation results will be presented for the proposed system. The simulation results obtained by comparing the classic UWB system and the proposed system show that our solution gives good performances in terms of BER and data rate. The theoretical results of BER values will be given for our proposed solution. In the second stage, we will compute BER values for different jitter effects. Theses studies report theoretical and simulation performances evaluation in the case of two 展开更多
关键词 UWB Orthogonal WAVEFORM PPM Pulse Position MODULATION and Antipodal MODULATION JITTER MULTIUSER
下载PDF
上一页 1 2 21 下一页 到第
使用帮助 返回顶部