Color Doppler was used to examine the blood flow velocity wave forms of fetal middle cerebral artery (MCA) and umbilical artery (UA) in normal pregnancy (58 cases) pregnancy induced hypertension (PIH) with fetal growt...Color Doppler was used to examine the blood flow velocity wave forms of fetal middle cerebral artery (MCA) and umbilical artery (UA) in normal pregnancy (58 cases) pregnancy induced hypertension (PIH) with fetal growth retardation (IUGR) (54 cases) and without IUGR (34 cases). The peak-systolic / diastole ratio (S/D), pulse index (PI) and resistance index (RI) values of MCA and UA were calcu-展开更多
The lower frequency part of the theoretical wind wave spectrum proposed by the authors (Wen et al. , 1988a, b,c) has been improved and the form of spectrum is appreciably simplified. In addition to the field data coll...The lower frequency part of the theoretical wind wave spectrum proposed by the authors (Wen et al. , 1988a, b,c) has been improved and the form of spectrum is appreciably simplified. In addition to the field data collected in the Bohai Sea region and used in the previous papers, those obtained in the Huanghai Sea, the East China Sea and the South China Sea have been employed so that the improved spectra can be verified on a more extensive observational basis. Computed results agree with the observations well. Further comparisons have been made between the proposed spectra and the JONSWAP spectrum. Though the two types of spectrum are close to each other in form, the former shows, as a whole, better agreement with the observation than the latter. By introducing an improved relation between the peak-ness factor and significant wave steepness, the spectrum contains only significant wave height and period as parameters. For spectra given in this form, the computed peak frequencies coincide approximately with observed values and the computed peak magnitudes of spectra agree basically with observations, but, because of the statistic variability inherent in the measurements of significant wave heights and periods, there are certain discrepancies between computed and measured spectrum peak magnitudes.展开更多
Metal sheet plastic deformation or forming is gener at ed through a mechanical pressure or a thermal variation. These pressure variatio ns or thermal variations can be created by a variety of means such as press form ...Metal sheet plastic deformation or forming is gener at ed through a mechanical pressure or a thermal variation. These pressure variatio ns or thermal variations can be created by a variety of means such as press form ing, hydroforming, imploding detonation and so on. According to the magnitude of the strain rates all these forming methods can be divided into quasi-static fo rming and dynamical forming. Up to now there are no reports of forming methods w ith the strain rates above 10 5sec -1, even though the exploding forming. In this article, we work on a dynamic super-speed forming method driven by lase r shock waves and advanced a novel concept of laser shock forming. The initial o bservation of the laser shock forming is done through a bugle testing with speci mens of SUS430 sheet metal, using a neodymium-glass laser of pulse energy 10J～ 3 0J and duration of 20 ns (FWHM). The investigation revealed that the plastic de formation during the laser shock forming is characterized as ultrahigh strain ra te up to 10 7sec -1. We indicate that plastic deformation increases nonlin early when the energy density of the laser varies. By investigating the hardness and residual stress of the surfaces, we conclude that laser shock forming is a combination technique of laser shock strengthening and metal forming for introdu cing a strain harden and a compressive residual stress on the surface of the wor k-piece, and the treated surface by laser shock forming has good properties in fatigue and corrosion resistance. This technique can achieve forming wit h or without mould.展开更多
The spectral form of wind waves is investigated based on the ocean wave data observed at three nearshore stations of Taiwan. In this study, the generalized forms of Pierson-Moskowitz spectrum and JONSWAP spectrum are ...The spectral form of wind waves is investigated based on the ocean wave data observed at three nearshore stations of Taiwan. In this study, the generalized forms of Pierson-Moskowitz spectrum and JONSWAP spectrum are used to describe the local wave spectrum by selecting suitable spectral form parameters. It is shown that, at a specific site, the similarity of wave spectral form exists. Thus it is possible to use a representative spectral form for a given nearshore region to describe the wave spectrum at this nearshore. On the other hand, the effects of relative water depth on spectral form are examined. The feasibility of two spectral models in finite water depth is evaluated by using the same field wave data.展开更多
We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found ...We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.展开更多
Taking the (2+1)-dimensional Broer-Kaup-Kupershmidt system as a simple example, some families of rational form solitary wave solutions, triangular periodic wave solutions, and rational wave solutions are constructed b...Taking the (2+1)-dimensional Broer-Kaup-Kupershmidt system as a simple example, some families of rational form solitary wave solutions, triangular periodic wave solutions, and rational wave solutions are constructed by using the Riccati equation rational expansion method presented by us. The method can also be applied to solve more nonlinear partial differential equation or equations.展开更多
In this work we devise an algebraic method to uniformly construct rational form solitary wave solutions and Jacobi and Weierstrass doubly periodic wave solutions of physical interest for nonlinear evolution equations....In this work we devise an algebraic method to uniformly construct rational form solitary wave solutions and Jacobi and Weierstrass doubly periodic wave solutions of physical interest for nonlinear evolution equations. With the aid of symbolic computation, we apply the proposed method to solving the (1+1)-dimensional dispersive long wave equation and explicitly construct a series of exact solutions which include the rational form solitary wave solutions and elliptic doubly periodic wave solutions as special cases.展开更多
A closed-form analytic solution of two-dimensional scattering and diffraction of plane SH waves by a semi- cylindrical hill with a semi-cylindrical concentric tunnel inside an elastic half-space is presented using the...A closed-form analytic solution of two-dimensional scattering and diffraction of plane SH waves by a semi- cylindrical hill with a semi-cylindrical concentric tunnel inside an elastic half-space is presented using the cylindrical wave functions expansion method.The solution is reduced to solving a set of infinite linear algebraic equations.Fourier expansion theorem with the form of complex exponential function and cosine function is used.Numerical solutions are obtained by truncation of the infinite equations.The accuracy of the presented numerical results is carefully verified.展开更多
A new load surface based approach to the reliability analysis of caisson-type breakwater is proposed. Uncertainties of the horizontal and vertical wave loads acting on breakwater are considered by using the so-called ...A new load surface based approach to the reliability analysis of caisson-type breakwater is proposed. Uncertainties of the horizontal and vertical wave loads acting on breakwater are considered by using the so-called load surfaces, which can be estimated as functions of wave height, water level, and so on. Then, the first-order reliability method（FORM） can be applied to determine the probability of failure under the wave action. In this way, the reliability analysis of breakwaters with uncertainties both in wave height and in water level is possible. Moreover, the uncertainty in wave breaking can be taken into account by considering a random variable for wave height ratio which relates the significant wave height to the maximum wave height. The proposed approach is applied numerically to the reliability analysis of caisson breakwater under wave attack that may undergo partial or full wave breaking.展开更多
An analytical model for calculating the propagation time of shock wave in a wave shaper is presented in this study. The calculated results show that the contours of three typical detonation waves, such as conical deto...An analytical model for calculating the propagation time of shock wave in a wave shaper is presented in this study. The calculated results show that the contours of three typical detonation waves, such as conical detonation wave, spherical detonation wave, and planar detonation wave, can be formed in the main charge by changing the thickness of wave shaper.The results show that the planar detonation wave do better than the conical detonation and the spherical detonation wave in increasing the length–diameter ratio of explosively-formed projectiles(EFP) and keep the nose of EFP integrated. The detonation wave can increase the length–diameter ratio of EFP when the wave shaper has the suitable thickness.展开更多
This paper presents a closed-form solution for diffraction of plane SH waves by a semi-circular cavity in half-space by using wave function expansion method. Accuracy of the solution is checked by the displacement res...This paper presents a closed-form solution for diffraction of plane SH waves by a semi-circular cavity in half-space by using wave function expansion method. Accuracy of the solution is checked by the displacement residual and stress residual along the boundaries. Numerical results show that there are notable differences for response amplitudes between a semi-circular cavity and a whole-circular cavity in a half-space.展开更多
Considered under their standard form, the fifth-order KdV equations are a sort of reading table on which new prototypes of higher order solitary waves residing there, have been uncovered and revealed to broad daylight...Considered under their standard form, the fifth-order KdV equations are a sort of reading table on which new prototypes of higher order solitary waves residing there, have been uncovered and revealed to broad daylight. The mathematical tool that made it possible to explore and analyze this equation is the Bogning-Djeumen Tchaho-Kofané method extended to the new implicit Bogning' functions. The analytical form of the solutions chosen in this manuscript is particular in the sense that it contains within its bosom, a package of solitary waves made up of three solitons, especially, the bright type soliton, the hybrid soliton and the dark type soliton which we estimate capable in their interactions of generating new hybrid or multi-form solitons. Existence conditions of the obtained solitons have been determined. It emerges that, these existence conditions of the chosen ansatz could open the way to other new varieties of fifth-order KdV equations including to which it will be one of the solutions. Some of the obtained solitons are exact solutions. Intense numerical simulations highlighted numerical stability and confirmed the hybrid character of the obtained solutions. These results will help to model new nonlinear wave phenomena, in plasma media and in fluid dynamics, especially, on the shallow water surface.展开更多
Lightweight design is one of the development trends of the automobile industry. An effective way to achieve lightweight auto bodies is to use AHSS （advanced high strength steel ） for the safety components of automob...Lightweight design is one of the development trends of the automobile industry. An effective way to achieve lightweight auto bodies is to use AHSS （advanced high strength steel ） for the safety components of automobiles. This study has taken doorsill reinforcements made of martensite AHSS as the object ,and performed research on the AHSS roll forming technologies and prototype development of typical asymmetric open components. By means of finite element analysis （FEA） and simulation,studies have been carried out on the springback and edge wave defects during AHSS roll forming ,and an optimized process design has been achieved. The generation mechanisms of vertical bows ,horizontal cambers, twists,pre-punched hole distortion and cut end flare have been analyzed,and solutions to these defects have been given. In addition,tesing of the roll forming process for AHSS has been conducted and typical samples with required dimensional accuracy have been manufactured. This study has provided technical support for the large-scale application of AHSS.展开更多
In this paper, the characteristics of laboratory wind waves under various wind speeds and water depths are studied. It is found that either the real or the imaginary part of the bispectrum can be related to the asymme...In this paper, the characteristics of laboratory wind waves under various wind speeds and water depths are studied. It is found that either the real or the imaginary part of the bispectrum can be related to the asymmetry of the wave profile, and the bicoherence is related to the ratio of nonlinear to linear wave component. Occasionally, these two categories of nonlinear index lead to opposite inferences, because each of them has its own significance and functions. The applicability of linear wave spectral model in ocean waves becomes questionable only when strong nonlinearity is indicated by both of these two indexes, The linear spectral representation of wave fields does not necessarily become inadequate as water depth decreases, and its appropriateness can be examined through the characteristics of the bispectrum.展开更多
Performance of explosive energy is rated in a number of ways, obtained either from theoretical calculations or from experimental tests. However, it is difficult to determine the amount of the explosive energy transfer...Performance of explosive energy is rated in a number of ways, obtained either from theoretical calculations or from experimental tests. However, it is difficult to determine the amount of the explosive energy transferred to the rock and converted into efficient work in the application of rock blasting. Although measurement of some of the effects of explosive energy in rock mass is ground vibration, noise, etc., which are usually conducted for blast control/analysis purpose, the results are rarely used on energy content. Energy transferred to the rock in the form of seismic waves is called seismic energy. In conventional analysis of blast results, generally, the ground vibrations generated due to blasting operations are monitored at a known distance from blast site with a geophone/ground vibration monitor, in three mutually orthogonal directions. Using such wave forms, an energy component is estimated from all the wave forms in three directions, using a sophisticated signal processing software, which is termed as “wave energy”. The wave energy is compared with the estimated seismic energy. An investigating program was taken up involving 31 blasts conducted at a hard rock excavation site to assess the influence of depth of excavation and scaled distance on the seismic energy wasted in the form of ground vibrations.展开更多
Present paper researches the theoretical method for calculating the wave resistance of wave piercing catamarans.As an example the wave resistance of a wave piercing csatamaran is calculated.The comparison among the th...Present paper researches the theoretical method for calculating the wave resistance of wave piercing catamarans.As an example the wave resistance of a wave piercing csatamaran is calculated.The comparison among the theoretical calculation results,the model test results and the diagram evaluation results shows the efficiency of present theoretical method.At last the dependence wave resistance of wave piercing catamarans on some parameters is investigated based on the theoretical method.展开更多
A closed-form wave function analytic solution of two-dimensional scattering and diffraction of incident plane SH-waves by a fl exible wall on a rigid shallow circular foundation embedded in an elastic half-space is pr...A closed-form wave function analytic solution of two-dimensional scattering and diffraction of incident plane SH-waves by a fl exible wall on a rigid shallow circular foundation embedded in an elastic half-space is presented. This research generalizes the previous solution by Trifunac in 1972, which tackled only the semi-circular foundation, to arbitrary shallow circular-arc foundation cases, and is thus comparatively more realistic. Ground surface displacement spectra at higher frequencies are also obtained. As an analytical series solution, the accuracy and error analysis of the numerical results are also discussed. It was observed from the results that the rise-to-span ratio of the foundation profi le, frequency of incident waves, and mass ratios of different media(foundation-structure-soil) are the three primary factors that may affect the surface ground motion amplitudes near the structure.展开更多
When a 2-D progressive wave train normally or obliquely approaches a vertical wall and then is normally or obliquely reflected from it, the combination of the approaching and reflected waves may result in a standing w...When a 2-D progressive wave train normally or obliquely approaches a vertical wall and then is normally or obliquely reflected from it, the combination of the approaching and reflected waves may result in a standing wave or a short-crested wave in front of the wall. This paper presents the experimental observations of sand bed configurations under the action of these water waves in front of the wall. The geometry of sand ripples under these water waves in front of the vertical wall is presented as a function of flow parameters, such as the water particle semi-excursion and the mobility number.展开更多
文摘Color Doppler was used to examine the blood flow velocity wave forms of fetal middle cerebral artery (MCA) and umbilical artery (UA) in normal pregnancy (58 cases) pregnancy induced hypertension (PIH) with fetal growth retardation (IUGR) (54 cases) and without IUGR (34 cases). The peak-systolic / diastole ratio (S/D), pulse index (PI) and resistance index (RI) values of MCA and UA were calcu-
文摘The lower frequency part of the theoretical wind wave spectrum proposed by the authors (Wen et al. , 1988a, b,c) has been improved and the form of spectrum is appreciably simplified. In addition to the field data collected in the Bohai Sea region and used in the previous papers, those obtained in the Huanghai Sea, the East China Sea and the South China Sea have been employed so that the improved spectra can be verified on a more extensive observational basis. Computed results agree with the observations well. Further comparisons have been made between the proposed spectra and the JONSWAP spectrum. Though the two types of spectrum are close to each other in form, the former shows, as a whole, better agreement with the observation than the latter. By introducing an improved relation between the peak-ness factor and significant wave steepness, the spectrum contains only significant wave height and period as parameters. For spectra given in this form, the computed peak frequencies coincide approximately with observed values and the computed peak magnitudes of spectra agree basically with observations, but, because of the statistic variability inherent in the measurements of significant wave heights and periods, there are certain discrepancies between computed and measured spectrum peak magnitudes.
文摘Metal sheet plastic deformation or forming is gener at ed through a mechanical pressure or a thermal variation. These pressure variatio ns or thermal variations can be created by a variety of means such as press form ing, hydroforming, imploding detonation and so on. According to the magnitude of the strain rates all these forming methods can be divided into quasi-static fo rming and dynamical forming. Up to now there are no reports of forming methods w ith the strain rates above 10 5sec -1, even though the exploding forming. In this article, we work on a dynamic super-speed forming method driven by lase r shock waves and advanced a novel concept of laser shock forming. The initial o bservation of the laser shock forming is done through a bugle testing with speci mens of SUS430 sheet metal, using a neodymium-glass laser of pulse energy 10J～ 3 0J and duration of 20 ns (FWHM). The investigation revealed that the plastic de formation during the laser shock forming is characterized as ultrahigh strain ra te up to 10 7sec -1. We indicate that plastic deformation increases nonlin early when the energy density of the laser varies. By investigating the hardness and residual stress of the surfaces, we conclude that laser shock forming is a combination technique of laser shock strengthening and metal forming for introdu cing a strain harden and a compressive residual stress on the surface of the wor k-piece, and the treated surface by laser shock forming has good properties in fatigue and corrosion resistance. This technique can achieve forming wit h or without mould.
文摘The spectral form of wind waves is investigated based on the ocean wave data observed at three nearshore stations of Taiwan. In this study, the generalized forms of Pierson-Moskowitz spectrum and JONSWAP spectrum are used to describe the local wave spectrum by selecting suitable spectral form parameters. It is shown that, at a specific site, the similarity of wave spectral form exists. Thus it is possible to use a representative spectral form for a given nearshore region to describe the wave spectrum at this nearshore. On the other hand, the effects of relative water depth on spectral form are examined. The feasibility of two spectral models in finite water depth is evaluated by using the same field wave data.
基金Supported by the Ministry of Education and Science of Ukraine under Grant No 0117U002253
文摘We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.
文摘Taking the (2+1)-dimensional Broer-Kaup-Kupershmidt system as a simple example, some families of rational form solitary wave solutions, triangular periodic wave solutions, and rational wave solutions are constructed by using the Riccati equation rational expansion method presented by us. The method can also be applied to solve more nonlinear partial differential equation or equations.
文摘In this work we devise an algebraic method to uniformly construct rational form solitary wave solutions and Jacobi and Weierstrass doubly periodic wave solutions of physical interest for nonlinear evolution equations. With the aid of symbolic computation, we apply the proposed method to solving the (1+1)-dimensional dispersive long wave equation and explicitly construct a series of exact solutions which include the rational form solitary wave solutions and elliptic doubly periodic wave solutions as special cases.
文摘A closed-form analytic solution of two-dimensional scattering and diffraction of plane SH waves by a semi- cylindrical hill with a semi-cylindrical concentric tunnel inside an elastic half-space is presented using the cylindrical wave functions expansion method.The solution is reduced to solving a set of infinite linear algebraic equations.Fourier expansion theorem with the form of complex exponential function and cosine function is used.Numerical solutions are obtained by truncation of the infinite equations.The accuracy of the presented numerical results is carefully verified.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology(Grant No.NRF-2012R1A1A4A01010830)
文摘A new load surface based approach to the reliability analysis of caisson-type breakwater is proposed. Uncertainties of the horizontal and vertical wave loads acting on breakwater are considered by using the so-called load surfaces, which can be estimated as functions of wave height, water level, and so on. Then, the first-order reliability method（FORM） can be applied to determine the probability of failure under the wave action. In this way, the reliability analysis of breakwaters with uncertainties both in wave height and in water level is possible. Moreover, the uncertainty in wave breaking can be taken into account by considering a random variable for wave height ratio which relates the significant wave height to the maximum wave height. The proposed approach is applied numerically to the reliability analysis of caisson breakwater under wave attack that may undergo partial or full wave breaking.
文摘An analytical model for calculating the propagation time of shock wave in a wave shaper is presented in this study. The calculated results show that the contours of three typical detonation waves, such as conical detonation wave, spherical detonation wave, and planar detonation wave, can be formed in the main charge by changing the thickness of wave shaper.The results show that the planar detonation wave do better than the conical detonation and the spherical detonation wave in increasing the length–diameter ratio of explosively-formed projectiles(EFP) and keep the nose of EFP integrated. The detonation wave can increase the length–diameter ratio of EFP when the wave shaper has the suitable thickness.
基金supported by National Natural Science Foundation of China (No. 50978183)Tianjin Natural Science Foundation (No. 07JCZDJC10100)
文摘This paper presents a closed-form solution for diffraction of plane SH waves by a semi-circular cavity in half-space by using wave function expansion method. Accuracy of the solution is checked by the displacement residual and stress residual along the boundaries. Numerical results show that there are notable differences for response amplitudes between a semi-circular cavity and a whole-circular cavity in a half-space.
文摘Considered under their standard form, the fifth-order KdV equations are a sort of reading table on which new prototypes of higher order solitary waves residing there, have been uncovered and revealed to broad daylight. The mathematical tool that made it possible to explore and analyze this equation is the Bogning-Djeumen Tchaho-Kofané method extended to the new implicit Bogning' functions. The analytical form of the solutions chosen in this manuscript is particular in the sense that it contains within its bosom, a package of solitary waves made up of three solitons, especially, the bright type soliton, the hybrid soliton and the dark type soliton which we estimate capable in their interactions of generating new hybrid or multi-form solitons. Existence conditions of the obtained solitons have been determined. It emerges that, these existence conditions of the chosen ansatz could open the way to other new varieties of fifth-order KdV equations including to which it will be one of the solutions. Some of the obtained solitons are exact solutions. Intense numerical simulations highlighted numerical stability and confirmed the hybrid character of the obtained solutions. These results will help to model new nonlinear wave phenomena, in plasma media and in fluid dynamics, especially, on the shallow water surface.
文摘Lightweight design is one of the development trends of the automobile industry. An effective way to achieve lightweight auto bodies is to use AHSS （advanced high strength steel ） for the safety components of automobiles. This study has taken doorsill reinforcements made of martensite AHSS as the object ,and performed research on the AHSS roll forming technologies and prototype development of typical asymmetric open components. By means of finite element analysis （FEA） and simulation,studies have been carried out on the springback and edge wave defects during AHSS roll forming ,and an optimized process design has been achieved. The generation mechanisms of vertical bows ,horizontal cambers, twists,pre-punched hole distortion and cut end flare have been analyzed,and solutions to these defects have been given. In addition,tesing of the roll forming process for AHSS has been conducted and typical samples with required dimensional accuracy have been manufactured. This study has provided technical support for the large-scale application of AHSS.
文摘In this paper, the characteristics of laboratory wind waves under various wind speeds and water depths are studied. It is found that either the real or the imaginary part of the bispectrum can be related to the asymmetry of the wave profile, and the bicoherence is related to the ratio of nonlinear to linear wave component. Occasionally, these two categories of nonlinear index lead to opposite inferences, because each of them has its own significance and functions. The applicability of linear wave spectral model in ocean waves becomes questionable only when strong nonlinearity is indicated by both of these two indexes, The linear spectral representation of wave fields does not necessarily become inadequate as water depth decreases, and its appropriateness can be examined through the characteristics of the bispectrum.
文摘Performance of explosive energy is rated in a number of ways, obtained either from theoretical calculations or from experimental tests. However, it is difficult to determine the amount of the explosive energy transferred to the rock and converted into efficient work in the application of rock blasting. Although measurement of some of the effects of explosive energy in rock mass is ground vibration, noise, etc., which are usually conducted for blast control/analysis purpose, the results are rarely used on energy content. Energy transferred to the rock in the form of seismic waves is called seismic energy. In conventional analysis of blast results, generally, the ground vibrations generated due to blasting operations are monitored at a known distance from blast site with a geophone/ground vibration monitor, in three mutually orthogonal directions. Using such wave forms, an energy component is estimated from all the wave forms in three directions, using a sophisticated signal processing software, which is termed as “wave energy”. The wave energy is compared with the estimated seismic energy. An investigating program was taken up involving 31 blasts conducted at a hard rock excavation site to assess the influence of depth of excavation and scaled distance on the seismic energy wasted in the form of ground vibrations.
文摘Present paper researches the theoretical method for calculating the wave resistance of wave piercing catamarans.As an example the wave resistance of a wave piercing csatamaran is calculated.The comparison among the theoretical calculation results,the model test results and the diagram evaluation results shows the efficiency of present theoretical method.At last the dependence wave resistance of wave piercing catamarans on some parameters is investigated based on the theoretical method.
文摘A closed-form wave function analytic solution of two-dimensional scattering and diffraction of incident plane SH-waves by a fl exible wall on a rigid shallow circular foundation embedded in an elastic half-space is presented. This research generalizes the previous solution by Trifunac in 1972, which tackled only the semi-circular foundation, to arbitrary shallow circular-arc foundation cases, and is thus comparatively more realistic. Ground surface displacement spectra at higher frequencies are also obtained. As an analytical series solution, the accuracy and error analysis of the numerical results are also discussed. It was observed from the results that the rise-to-span ratio of the foundation profi le, frequency of incident waves, and mass ratios of different media(foundation-structure-soil) are the three primary factors that may affect the surface ground motion amplitudes near the structure.
文摘When a 2-D progressive wave train normally or obliquely approaches a vertical wall and then is normally or obliquely reflected from it, the combination of the approaching and reflected waves may result in a standing wave or a short-crested wave in front of the wall. This paper presents the experimental observations of sand bed configurations under the action of these water waves in front of the wall. The geometry of sand ripples under these water waves in front of the vertical wall is presented as a function of flow parameters, such as the water particle semi-excursion and the mobility number.
