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摩洛哥大西洋沿岸的波能评估 预览
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作者 Hafsa Bouhrim Abdellatif El Marjani 《船舶与海洋工程学报:英文版》 CSCD 2019年第2期142-152,共11页
The aim of the present work is to assess the offshore wave energy potential along the Atlantic coast of Morocco.Research works of this paper focus on the identification of the most energetic sites for wave energy conv... The aim of the present work is to assess the offshore wave energy potential along the Atlantic coast of Morocco.Research works of this paper focus on the identification of the most energetic sites for wave energy converters(WECs)deployment.For this purpose,11 sites have been explored;all of them are located at more than 40m depth on the Moroccan Atlantic coast.The wave power at each site is computed on the basis of wave data records in terms of significant wave height and energy period provided by theWaveWatch three(WW3)model.Results indicate that the coast sites located between latitudes 30°30′N and 33°N are the most energetic with an annual average wave power estimated at about 30 kW?m^-1,whereas,in the other sites,the wave power is significantly lower.Moreover,the study of the monthly and seasonal temporal variability is found to be uniform in the powerful sites with values four times greater in winter than in summer.The directional investigation on the significant wave height has shown that for almost all the powerful sites,the incoming waves have a dominant sector ranging between Northern(N)and Western-Northern-Western(WNW)directions. 展开更多
关键词 WAVE ENERGY MOROCCAN ATLANTIC coast WAVE ENERGY converter(WEC) WAVE Watch 3(WW3) Seasonal and temporal variability Directional WAVE height investigation Power ROSES Occurrence BIVARIATE distributions
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Wave prediction in a port using a fully nonlinear Boussinesq wave model 预览
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作者 Young-Kwang Choi Seung-Nam Seo +2 位作者 Jin-Yong Choi Fengyan Shi Kwang-Soon Park 《海洋学报:英文版》 SCIE CAS CSCD 2019年第7期36-47,共12页
A wave forecasting system using FUNWAVE-TVD which is based on the fully nonlinear Boussinesq equations by Chen(2006)was developed to provide an accurate wave prediction in the Port of Busan,South Korea.This system is ... A wave forecasting system using FUNWAVE-TVD which is based on the fully nonlinear Boussinesq equations by Chen(2006)was developed to provide an accurate wave prediction in the Port of Busan,South Korea.This system is linked to the Korea Operational Oceanographic System(KOOS)developed by Park et al.(2015).The computational domain covers a region of 9.6 km×7.0 km with a grid size of 2 m in both directions,which is sufficient to resolve short waves and dominant sea states.The total number of grid points exceeds 16 millions,making the model computational expensive.To provide real-time forecasting,an interpolation method,which is based on pre-calculated results of FUNWAVE-TVD and SWAN forecasting results at the FUNWAVE-TVD offshore boundary,was used.A total of 45 cases were pre-calculated,which took 71 days on 924 computational cores of a Linux cluster system.Wind wave generation and propagation from the deep water were computed using the SWAN in KOOS.SWAN results provided a boundary condition for the FUNWAVE-TVD forecasting system.To verify the model,wave observations were conducted at three locations inside the port in a time period of more than 7 months.A model/model comparison between FUNWAVE-TVD and SWAN was also carried out.It is found that,FUNWAVE-TVD improves the forecasting results significantly compared to SWAN which underestimates wave heights in sheltered areas due to incorrect physical mechanism of wave diffraction,as well as large wave heights caused by wave reflections inside the port. 展开更多
关键词 real-time WAVE forecasting FUNWAVE-TVD SWAN KOOS WAVE observations WAVE DIFFRACTION
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Wave packet solutions in a bounded equatorial ocean and its interannual and decadal variabilities 预览
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作者 Dongling Zhang Juan Zhu +1 位作者 Xu Lu Ming Zhang 《海洋学报:英文版》 SCIE CAS CSCD 2019年第3期45-59,共15页
Linearized shallow water perturbation equations with approximation in an equatorial β plane are used to obtain the analytical solution of wave packet anomalies in the upper bounded equatorial ocean. The main results ... Linearized shallow water perturbation equations with approximation in an equatorial β plane are used to obtain the analytical solution of wave packet anomalies in the upper bounded equatorial ocean. The main results are as follows. The wave packet is a superposition of eastward travelling Kelvin waves and westward travelling Rossby waves with the slowest speed, and satisfies the boundary conditions of eastern and western coasts, respectively.The decay coefficient of this solution to the north and south sides of the equator is inversely proportional only to the phase velocity of Kelvin waves in the upper water. The oscillation frequency of the wave packet, which is also the natural frequency of the ocean, is proportional to its mode number and the phase velocity of Kelvin waves and is inversely proportional to the length of the equatorial ocean in the east-west direction. The flow anomalies of the wave packet of Mode 1 most of the time appear as zonal flows with the same direction. They reach the maximum at the center of the equatorial ocean and decay rapidly away from the equator, manifested as equatorially trapped waves. The flow anomalies of the wave packet of Mode 2 appear as the zonal flows with the same direction most of the time in half of the ocean, and are always 0 at the center of the entire ocean which indicates stagnation, while decaying away from the equator with the same speed as that of Mode 1. The spatial structure and oscillation period of the wave packet solution of Mode 1 and Mode 2 are consistent with the changing periods of the surface spatial field and time coefficient of the first and second modes of complex empirical orthogonal function(EOF)analysis of flow anomalies in the actual equatorial ocean. This indicates that the solution does exist in the real ocean, and that El Ni?o-Southern Oscillation(ENSO) and Indian Ocean dipole(IOD) are both related to Mode 2.After considering the Indonesian throughflow, we can obtain the length of bounded equatorial ocean by taking the sum of that of the t 展开更多
关键词 BOUNDED EQUATORIAL OCEAN WAVE packet SOLUTIONS DECADAL variability Kelvin WAVE Rossby WAVE
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Influences of bubble size distribution on propagation of acoustic waves in dilute polydisperse bubbly liquids 预览
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作者 Yu-ning Zhang Zi-biao Jiang +4 位作者 Jin Yuan Ting Chen Yu-ning Zhang1 Ning-ning Tang Xiao-ze Du 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第1期50-57,共8页
The present paper studies the influences of the bubble size distribution on the propagation of acoustic waves in dilute polydisperse bubbly liquids theoretically.The proposed approach is validated by using available e... The present paper studies the influences of the bubble size distribution on the propagation of acoustic waves in dilute polydisperse bubbly liquids theoretically.The proposed approach is validated by using available experimental data in the literature.It is revealed that the bubble size distribution has impacts on both the wave speed and the wave attenuation.Specifically,the minimum wave speed together with the corresponding frequency could be both significantly affected by the bubble size distribution (e.g.,the standard deviation).Furthermore,the maximum wave attenuation in the frequency response curve is also sensitive to the variations of the bubble size distribution. 展开更多
关键词 Cavitation gas BUBBLES WAVE PROPAGATION WAVE speed WAVE attenuation
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Establishment of Numerical Wave Flume Based on the Second-Order Wave-Maker Theory 预览
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作者 ZHANG Hao-chen LIU Shu-xue +1 位作者 LI Jin-xuan WANG Lei 《中国海洋工程:英文版》 SCIE EI CSCD 2019年第2期160-171,共12页
With growing computational power, the first-order wave-maker theory has become well established and is widely used for numerical wave flumes. However, existing numerical models based on the first-order wave-maker theo... With growing computational power, the first-order wave-maker theory has become well established and is widely used for numerical wave flumes. However, existing numerical models based on the first-order wave-maker theory lose accuracy as nonlinear effects become prominent. Because spurious harmonic waves and primary waves have different propagation velocities, waves simulated by using the first-order wave-maker theory have an unstable wave profile. In this paper, a numerical wave flume with a piston-type wave-maker based on the second-order wave-maker theory has been established. Dynamic mesh technique was developed. The boundary treatment for irregular wave simulation was specially dealt with. Comparisons of the free-surface elevations using the first-order and second-order wave-maker theory prove that second-order wave-maker theory can generate stable wave profiles in both the spatial and time domains. Harmonic analysis and spectral analysis were used to prove the superiority of the second-order wave-maker theory from other two aspects. To simulate irregular waves, the numerical flume was improved to solve the problem of the water depth variation due to low-frequency motion of the wave board. In summary, the new numerical flume using the second-order wave-maker theory can guarantee the accuracy of waves by adding an extra motion of the wave board. The boundary treatment method can provide a reference for the improvement of nonlinear numerical flume. 展开更多
关键词 SECOND-ORDER WAVE generation nonlinear WAVE SPURIOUS HARMONIC WAVE numerical FLUME
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Magnetic Wave Transmission of Drug Effects about the Waves,Generated in the Measurement Set-Up and Used i.e.for Anticancer-Treatments 预览
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作者 Konstantin Meyl 《美中医学:英文版》 2019年第3期134-139,共6页
Longitudinal waves propagating in the direction of the magnetic field represents a special class according to the wave equation.They seem to be ubiquitous in nature,as can be shown by numerous natural phenomena.It is ... Longitudinal waves propagating in the direction of the magnetic field represents a special class according to the wave equation.They seem to be ubiquitous in nature,as can be shown by numerous natural phenomena.It is therefore possible that biological systems may use these waves as a medium or as a carrier wave for signal transfer.As longitudinal waves can also be generated technically,an experimental set up has been established in order to show that the wave is able to transfer biological signals effectively apart from any chemical contact.The schematic diagram of the transmitter is explained,the special properties of the magnetic wave,working at 6.78 MHz,as well as the biological antennas,acting as a receiver,are in the focus of the first part of the presentation.It will be referred,how a medical doctor in Spain is using the system for anticancer treatment i.e.,to encourage discussions on medical purposes. 展开更多
关键词 Biological signal transmission information transfer WAVE equation MAGNETIC WAVE carrier WAVE
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珠江口附近海域波浪场的数值计算与特征分析
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作者 邱文博 张永合 +1 位作者 胡轶群 李冠宇 《海洋湖沼通报》 CSCD 北大核心 2019年第4期14-21,共8页
本文以WRF模式输出结果作为风场驱动条件,采用SWAN和WAVEWATCHIII相嵌套的方法,对珠江口附近海域进行20年(1991-2010年)的波浪场数值计算。根据计算结果,分析了珠江口海域波高和周期的空间、时间变化特征。结果显示:珠江入海口及近岸Hs... 本文以WRF模式输出结果作为风场驱动条件,采用SWAN和WAVEWATCHIII相嵌套的方法,对珠江口附近海域进行20年(1991-2010年)的波浪场数值计算。根据计算结果,分析了珠江口海域波高和周期的空间、时间变化特征。结果显示:珠江入海口及近岸Hs较小,外海Hs较大,大部分海域年均Hs在0.4m以上;珠江口附近海域和近海地区年均Te偏小,在2s~3s之间,外海最大可达5s。珠江海域有效波高(Hs)的季节分布呈现出春夏季较小,秋冬季较大的特点。从概率学角度分别统计20年中前5%和10%的Hs及Te,可知:珠江口近海区域Hs,5%在1~2m,大万山群岛处可达Hs,5%2m;在珠江口附近Hs,10%为1.5m,万山海域Hs,10%在2.5m以上;计算海域Te,5%和Te,10%多在4s以上。 展开更多
关键词 珠江口海域 波浪 波周期 SWAN WAVEWATCHⅢ
Experimental investigation on the optical remote sensing images of internal solitary waves with a smooth surface 预览
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作者 Yuan Mei Jing Wang +2 位作者 Songsong Huang Haidi Mu Xu Chen 《海洋学报:英文版》 SCIE CAS CSCD 2019年第6期124-131,共8页
The parameter inversion of internal solitary waves (ISWs) based on optical remote sensing images is a key work. A new approach is proposed and demonstrated for simulating the optical remote sensing images of ISWs with... The parameter inversion of internal solitary waves (ISWs) based on optical remote sensing images is a key work. A new approach is proposed and demonstrated for simulating the optical remote sensing images of ISWs with a smooth surface in the laboratory. An optical remote sensing simulation system used to detect ISWs is constructed by a two-dimensional ISW flume, a LED (light emitting diode) light source and two CCD (charge coupled device) cameras. The optical remote sensing images of the horizontal surface and ISWs propagation images of a vertical side are detected simultaneously, which aims to explore the response of optical remote sensing corresponding to ISWs with the smooth surface. The results show that during the propagation of ISWs, dark pattern images are obtained by CCD 1 camera. The characteristics of the dark patterns vary along with the incident angle of the light source. The characteristic parameters of the optical remote sensing images correspond to the wave factors of vertical profiles. The experiment also shows a positive correlation between the dark pattern width and the half wave width under different amplitudes of ISWs. The system has the advantages of clear phenomenon and high repeatability, which provides the scientific basis for quantitative investigation on imaging mechanism of ISW by optical remote sensing. 展开更多
关键词 internal SOLITARY WAVE optical remote sensing image DARK pattern HALF WAVE WIDTH WAVE factors
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A 10-year wave energy resource assessment and trends of Indonesia based on satellite observations 预览
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作者 Amiruddin Agustinus Ribal +1 位作者 Khaeruddin Sri Astuti Thamrin 《海洋学报:英文版》 SCIE CAS CSCD 2019年第8期86-93,共8页
Wave energy resource assessment and trends around Indonesian’s ocean has been carried out by means of analyzing satellite observations. Wave energy flux or wave power can be approximated using parameterized sea state... Wave energy resource assessment and trends around Indonesian’s ocean has been carried out by means of analyzing satellite observations. Wave energy flux or wave power can be approximated using parameterized sea states derived from satellite data. Unfortunately, only some surface parameters can be measured from remote sensing satellites, for example for ocean surface waves: significant wave height. Others, like peak wave period and energy period are not available, but can instead be estimated using empirical models. The results have been assessed by meteorological season. The assessment shows clearly where and when the wave power resource is promising around Indonesian’s ocean. The most striking result was found from June to August, in which about 30–40 kW/m(the 90 th percentile: 40–60 kW/m, the 99th percentile: 50–70 kW/m) wave power energy on average has been found around south of the Java Island. The significant trends of wave energy at the 95% level have also been studied and it is found that the trends only occurred for the extreme cases, which is the 99th percentile(i.e.,highest 1%). Wave power energy could increase up to 150 W/m per year. The significant wave heights and wave power have been compared with the results obtained from global wave model hindcast carried out by wave model WAVEWATCH III. The comparisons indicated excellent agreements. 展开更多
关键词 WAVE power energy trends ENVISAT ALTIMETER SIGNIFICANT WAVE HEIGHT WAVE period
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Study on Energy Spectrum Instability in the Processes of Propagating and Breaking of Focusing Waves 预览
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作者 ZHANG Yi-hui LIANG Shu-xiu SUN Zhao-chen 《中国海洋工程:英文版》 SCIE EI CSCD 2019年第1期86-93,共8页
Based on phase focusing theory,focusing waves with different spectral types and breaking severities were generated in a wave flume.The time series of surface elevation fluctuation along the flume were obtained by util... Based on phase focusing theory,focusing waves with different spectral types and breaking severities were generated in a wave flume.The time series of surface elevation fluctuation along the flume were obtained by utilizing 22 wave probes mounted along the mid-stream of the flume.Based on the wave spectrum obtained using fast Fourier transform(FFT),the instability characteristics of the energy spectrum were reported in this paper.By analyzing the variation of total spectral energy,the total spectral energy after wave breaking was found to clearly decrease,and the loss value and ratio gradually increased and tended to stabilize with the enhancement of breaking severity for different spectral types.When wave breaking occurred,the energy loss was primarily in a high-frequency range of f/fp >1.0,and energy gain was primarily in a low-frequency range of f/fp<1.0.As the breaking severity increased,the energy gain-loss ratio decreased gradually,which demonstrates that the energy was mostly dissipated.For plunging waves,the energy gain-loss ratio reached 24%for the constant wave steepness(CWS)spectrum,and was slightly larger at approximately 30%for the constant wave amplitude(CWA)spectrum,and was the largest at approximately 42%for the Pierson-Moskowitz(PM)spectrum. 展开更多
关键词 phase FOCUSING WAVE BREAKING WAVE surface WAVE steepness
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Qualitative Description of Swashing Motion States on Mild Beach Slope 预览
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作者 YIN Jing ZOU Zhi-li +1 位作者 FANG Ke-zhao LIU Yan-li 《中国海洋工程:英文版》 SCIE EI CSCD 2019年第4期412-423,共12页
The swashing motion on mild beach slope is dominated by the motion of low frequency waves (LFWs). Companying such a motion, there are two types of swashing motion states, occurrence or no occurrence of LFW’s collisio... The swashing motion on mild beach slope is dominated by the motion of low frequency waves (LFWs). Companying such a motion, there are two types of swashing motion states, occurrence or no occurrence of LFW’s collision. The present study distinguishes the two states qualitatively by relating it to the number of generated LFWs for the case of two incident wave groups. A simplified swashing index is established theoretically for this purpose. A series of related experiments were performed to observe the generated out-going LFWs on different mild slope from 1:20 to 1:160 and to determine the critical value of the swashing index. Numerical simulations based on higher order Boussinesq equations are also performed to help the recognition of the LFWs generated in the experiment. 展开更多
关键词 swashing SURF BEAT BRAKING WAVE low frequency WAVE WAVE GROUPS
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基于Star-CCM+的摆式波浪能装置水动力性能研究 预览
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作者 元正 张亮 +2 位作者 周斌珍 金鹏 郑雄波 《船舶与海洋工程学报:英文版》 CSCD 2019年第2期153-159,共7页
A two-dimensional numerical Computational Fluid Dynamics(CFD)model is established on the basis of viscous CFD theory to investigate the motion response and power absorption performance of a bottom-hinged flap-type wav... A two-dimensional numerical Computational Fluid Dynamics(CFD)model is established on the basis of viscous CFD theory to investigate the motion response and power absorption performance of a bottom-hinged flap-type wave energy converter(WEC)under regular wave conditions.The convergence study of mesh size and time step is performed to ensure that wave height and motion response are sufficiently accurate.Wave height results reveal that the attenuation of wave height along the wave tank is less than 5%only if the suitable mesh size and time step are selected.The model proposed in this work is verified against published experimental and numerical models.The effects of mechanical damping,wave height,wave frequency,and water depth on the motion response,power generation,and energy conversion efficiency of the flap-type WEC are investigated.The selection of the appropriate mechanical damping of the WEC is crucial for the optimal extraction of wave power.The optimal mechanical damping can be readily predicted by using potential flow theory.It can then be verified by applying CFD numerical results.In addition,the motion response and the energy conversion efficiency of the WEC decrease as the incident wave height increases because the strengthened nonlinear effect of waves intensifies energy loss.Moreover,the energy conversion efficiency of theWEC decreases with increasing water depth and remains constant as the water depth reaches a critical value.Therefore,the selection of the optimal parameters during the design process is necessary to ensure that the WEC exhibits the maximum energy conversion efficiency. 展开更多
关键词 WAVE ENERGY CONVERTER Oyster.Energy conversion efficiency OptimumPTO DAMPING Nonlinear REGULAR WAVE
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大型水陆两栖飞机波浪水面着水分析方法 预览
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作者 孙丰 王明振 +1 位作者 褚林塘 张家旭 《航空计算技术》 2019年第4期35-38,共4页
水面环境对水陆两栖飞机着水载荷有重要影响,水面环境分为静水和波浪,采用数值仿真技术对静水面和波浪水面环境下的水陆两栖飞机着水载荷进行计算。利用单机身模型,通过与实验对比,验证仿真方法的有效性及精度;基于推板造波理论实现数... 水面环境对水陆两栖飞机着水载荷有重要影响,水面环境分为静水和波浪,采用数值仿真技术对静水面和波浪水面环境下的水陆两栖飞机着水载荷进行计算。利用单机身模型,通过与实验对比,验证仿真方法的有效性及精度;基于推板造波理论实现数值造波,结合静水面着水仿真技术实现波浪水面着水仿真。研究发现,静水面着水仿真精度较高,应用数值造波方法模拟的波浪品质可以满足工程应用。 展开更多
关键词 水陆两栖飞机 波浪 着水载荷 数值仿真 数值造波
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Pressure characteristics of landslide-generated impulse waves
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作者 TAN Jian-min HUANG Bo-lin ZHAO Yong-bo 《山地科学学报:英文版》 SCIE CSCD 2019年第8期1774-1787,共14页
The destructiveness of impulse waves generated by landslides(IWL) originates from the wave’s movement and load, wherein the impulse wave’s load is the major cause of sub-aerial building damage and casualties. In thi... The destructiveness of impulse waves generated by landslides(IWL) originates from the wave’s movement and load, wherein the impulse wave’s load is the major cause of sub-aerial building damage and casualties. In this study, an experiment involving 16 groups of physical tests for the wave pressure generated by a landslide was designed, consisting of 4 sets of IWL and 4 opposite bank slope angles. A high-frequency strain system was used to measure the total pressure of the impulse wave in a water tank. The tests showed that the dynamic pressure caused by the IWL can be divided into two types: impact pressure generated by the jetflow and the pulsating pressure caused by the wave. Under the same impulse wave conditions, the maximum run-up becomes smaller as the opposite bank’s slope angle increases, and the jetflow maximum impact pressure experienced by the opposite bank increases, while the maximum pulsating pressure caused by the impulse wave is slightly decreased. Different from previous studies, the spatial maximum pressure distributions of the wave generated by landslide were concluded that the position of the maximum pulsating pressure appears adjacent to the still water surface, and the overall spatial distribution pattern of maximum wave pressure is presented as an inclined 'M' shape.Meanwhile, this study is the first to quantitatively analyzed that impact pressure has a very short action time, is even 7 times of the pulse pressure value, and there is a simple mathematical linear relationship between the two. Currently, some wave-load formulas for wind waves and tides are not applicable to calculating the loads of IWL. Research on the load of IWL will explain the hazard of impulse wave very clearly, and will greatly contribute to hazard prevention, mitigation and risk assessment work associated with IWL. 展开更多
关键词 LANDSLIDE IMPULSE WAVE WAVE PRESSURE Impact PRESSURE Pulsating PRESSURE PRESSURE distribution
Development of an Omni-Directional Shear Horizontal Wave Transducer Based on a Radially Poled Piezoelec trie Ring
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作者 Qiang Huan Mingtong Chen +1 位作者 Ai-Kah Soh Faxin Li 《固体力学学报:英文版》 SCIE EI CSCD 2019年第1期29-39,共11页
For the inspection of large plate-like structures,the omni-directional guided wave transducer-based system has been regarded as an effective tool since only a few transducers are required to cover the entire inspectio... For the inspection of large plate-like structures,the omni-directional guided wave transducer-based system has been regarded as an effective tool since only a few transducers are required to cover the entire inspection area without blind zones.In comparison with Lamb waves,the shear horizontal(SH)wave is more promising because its fundamental mode is non-dispersive.In this work,we proposed an omni-directional SH wave piezoelec trie t ransducer(OSH-PT)based on a radially poled d24-mode PZT ring.Eoth the finite element simulations and experiments were carried out to demonstrate its performance in generating and receiving SH°wave.Results showed that the radially poled OSH-PT could generate single-mode SHo wave and receive SHo wave only over a wide frequency range from 70 to 200 kHz.The obtained signal-to-noise ratio can reach up to 26 dB in generation and 24 dB in reception.The omni-directivity of this OSH-PT is also very good with the deviation only about 6%in both generation and reception of SHo wave.Considering its easy fabrication,low cost and superior performances,this proposed OSH-PT may promote the applications of SHo wave-based inspection in structural health monitoring and nondestructive testing. 展开更多
关键词 OMNI-DIRECTIONAL Guided WAVE SHEAR HORIZONTAL WAVE Piezoelec TRIE t ransducer
基于Wave软件的某车型排气系统仿真分析 预览
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作者 王新国 袁建新 《景德镇学院学报》 2019年第3期34-37,共4页
讨论了使用Wave软件进行排气系统仿真分析的方法,简述了Wave软件功能及分析应用方向.以排气系统噪声分析及温度场分析为例,结合昌河汽车某车型排气系统开发,阐述了排气系统声学分析及温度场分析的方法.
关键词 排气系统 消声器 WAVE NVH
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The prospects of using gravitational waves for constraining the anisotropy of the Universe
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作者 赵志超 林海南 常哲 《中国物理C:英文版》 SCIE CAS CSCD 2019年第7期112-117,共6页
The observation of GW150914 gave a new independent measurement of the luminosity distance of a gravitational wave event. In this paper, we constrain the anisotropy of the Universe by using gravitational wave events.We... The observation of GW150914 gave a new independent measurement of the luminosity distance of a gravitational wave event. In this paper, we constrain the anisotropy of the Universe by using gravitational wave events.We simulate hundreds of events of binary neutron star merger that may be observed by the Einstein Telescope. Full simulation of the production process of gravitational wave data is employed. We find that 200 binary neutron star merging events with the redshift in (0,1) observed by the Einstein Telescope may constrain the anisotropy with an accuracy comparable to that from the Union2.1 supernovae. This result shows that gravitational waves can be a powerful tool for investigating cosmological anisotropy. 展开更多
关键词 GRAVITATIONAL WAVE ANISOTROPIC SPACE-TIME GRAVITATIONAL WAVE detector
Stress-dependent shear wave splitting and permeability in fractured porous rock 预览
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作者 Daisuke Katsuki Marte Gutierrez Abdulhadi Almrabat 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第1期1-11,共11页
It is well known that shear wave propagates slower across than parallel to a fracture,and as a result,a travelling shear wave splits into two directions when it encounters a fracture.Shear wave splitting and permeabil... It is well known that shear wave propagates slower across than parallel to a fracture,and as a result,a travelling shear wave splits into two directions when it encounters a fracture.Shear wave splitting and permeability of porous rock core samples having single fracture were experimentally investigated using a high-pressure triaxial cell,which can measure seismic shear wave velocities in two directions mutually perpendicular to the sample axis in addition to the longitudinal compressive wave velocity.A single fracture was created in the samples using a modified Brazilian split test device,where the cylindrical sample edges were loaded on two diametrically opposite lines by sharp guillotines along the sample length.Based on tilt tests and fracture surface profilometry,the method of artificially induced tensile fracture in the sample was found to create repeatable fracture surfaces and morphologies.Seismic velocities of the fractured samples were determined under different levels of stress confinement and fracture shear displacement or mismatch.The effective confining stress was varied from 0.5 MPa to 55 MPa,while the fractures were mismatched by 0 mm,0.45 mm and 1 mm.The degree of matching of the fracture surfaces in the core samples was evaluated using the joint matching coefficient(JMC).Shear wave splitting,as measured by the difference in the magnitudes of shear wave velocities parallel(VS1)and perpendicular(VS2)to the fracture,is found to be insensitive to the degree of mismatching of the fracture joint surfaces at 2 MPa,and decreased and approached zero as the effective stress was increased.Simple models for the stress-and JMC-dependent shear wave splitting and fractured rock permeability were developed based on the experimental observations.The effects of the joint wall compressive strength(JCS),JMC and stress on the stress dependency of joint aperture were discussed in terms of hydro-mechanical response.Finally,a useful relationship between fractured rock permeability and shear wave splitting was found aft 展开更多
关键词 Fractured rock SANDSTONE STRESS DEPENDENCY Shear WAVE SPLITTING WAVE velocity PERMEABILITY Fracture stiffness Elastic modulus
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Time-Domain Full Waveform Inversion Using the GradientPreconditioning Based on Transmitted Wave Energy 预览
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作者 SONG Peng TAN Jun +6 位作者 LIU Zhaolun ZHANG Xiaobo LIU Baohua YU Kaiben LI Jinshan XIA Dongming XIE Chuang 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第4期859-867,共9页
The gradient preconditioning approach based on seismic wave energy can effectively avoid the huge memory consumption of the gradient preconditioning algorithms based on the Hessian matrix. However, the accuracy of thi... The gradient preconditioning approach based on seismic wave energy can effectively avoid the huge memory consumption of the gradient preconditioning algorithms based on the Hessian matrix. However, the accuracy of this approach is prone to be influ- enced by the energy of reflected waves. To tackle this problem, the paper proposes a new gradient preconditioning method based on the energy of transmitted waves. The approach scales the gradient through a precondition factor, which is calculated by the ‘ap- proximate transmission wavefield’ simulation based on the nonreflecting acoustic wave equation. The method requires no computing nor storing of the Hessian matrix and its inverse matrix. Furthermore, the proposed method can effectively eliminate the effects of geometric spreading and disproportionality in the gradient illumination. The results of model experiments show that the time-domain full waveform inversion (FWI) using the gradient preconditioning based on transmitted wave energy can achieve higher inversion accuracy for deep high-velocity bodies and their underlying strata in comparison with the one using the gradient preconditioning based on seismic wave energy. The field marine seismic data test shows that our proposed method is also highly applicable to the FWI of field marine seismic data. 展开更多
关键词 full WAVEFORM INVERSION GRADIENT PRECONDITIONING transmitted WAVE nonreflecting acoustic WAVE equation
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Optimized Numerical Model Based Assessment of Wave Power Potential of Marmara Sea 预览
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作者 ABDOLLAHZADEHMORADI Yasin OZGER Mehmet ALTUNKAYNAK Abdüsselam 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第2期293-304,共12页
Marmara Sea, located between Black Sea and Aegean Sea, is an important sea for ocean engineering activities. In this study, wave power potential of Marmara Sea was investigated using the third generation spectral wind... Marmara Sea, located between Black Sea and Aegean Sea, is an important sea for ocean engineering activities. In this study, wave power potential of Marmara Sea was investigated using the third generation spectral wind-wave model MIKE 21 SW with unstructured mesh. Wind data was obtained from ECMWF ERA-Interim re-analyses wind dataset at 10 m with a spatial resolution of 0.1? for the period of 1994 to 2014. The numerical model was calibrated with measured wave data from a buoy station located in Marmara Sea. Mesh optimization was also performed to obtain the most suitable mesh structure for the study area. This study is the first that dealt with the determination of wave energy potential of Marmara Sea. The numerical model results are presented in terms of monthly, seasonal and annual average of wave power flux(k W m-1). The maximum wave power flux is 1.13 kW m-1 and occurs in November. The overall annual mean wave power flux during 1994–2014 is found to be 0.27 kW m-1 in the offshore regions. 展开更多
关键词 MARMARA Sea MIKE 21 SW WAVE power POTENTIAL ECMWF BUOY WAVE data
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