Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism ...Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism which is proportional to Planck’s constant. This may be the result of two massless bosons (hypergluons) coupled by a preon (prequark) exchange. It also gives a physical explanation to the origin of the Planck constant, and origin of spin.展开更多
Background: Birds produce alarm calls to convey information about threats. Some Passerine alarm calls consist of several note strings, but few studies have examined their function. Previous studies have shown that Jap...Background: Birds produce alarm calls to convey information about threats. Some Passerine alarm calls consist of several note strings, but few studies have examined their function. Previous studies have shown that Japanese Tits(Parus minor) can alter the calling rate and number and combination of notes in response to predators. We previously found the combinations of note types in Japanese Tit alarm calls to be significantly different in response to the Sparrowhawk(Accipiter nisus) and Common Cuckoo(Cuculus canorus).Methods: Through playback experiments, we tested whether the note strings in Japanese Tit alarm calls to the Common Cuckoo have different functions in conveying information. The note strings of selected alarm calls were divided into the categories of C and D, and different calls were then constructed separately based on the two note string categories. Original alarm calls(C–D), C calls and D calls were played back to male Japanese Tits during the incubation period.Results: Male Japanese Tits had a significantly stronger response to C calls than to C–D calls, and they showed a significantly stronger response to both C and C–D calls than to D calls, suggesting that Japanese Tits discriminated between the C and D calls.Conclusions: Our study demonstrated that the C-and D-category note strings of Japanese Tit alarm calls to the Common Cuckoo have different functions, which supports the previous finding that different note strings in an alarm call can provide different information to receivers. However, the exact meanings of these note strings are not yet known, and further investigation is therefore required.展开更多
The Hamiltonian dynamics is adopted to solve the eigenvalue problem for transverse vibrations of axially moving strings. With the explicit Hamiltonian function the canonical equation of the free vibration is derived. ...The Hamiltonian dynamics is adopted to solve the eigenvalue problem for transverse vibrations of axially moving strings. With the explicit Hamiltonian function the canonical equation of the free vibration is derived. Non-singular modal functions are obtained through a linear, symplectic eigenvalue analysis, and the symplectic-type orthogonality conditions of modes are derived. Stability of the transverse motion is examined by means of analyzing the eigenvalues and their bifurcation, especially for strings transporting with the critical speed. It is pointed out that the motion of the string does not possess divergence instability at the critical speed due to the weak interaction between eigenvalue pairs. The expansion theorem is applied with the non-singular modal functions to solve the displacement response to free and forced vibrations. It is demonstrated that the modal functions can be used as the base functions for solving linear and nonlinear vibration problems.展开更多
The flashover of insulator strings occurring at normal working voltages undercontaminated/polluted conditions, obviously deserves serious consideration. Though much researchhas been gone into pollution-induced flashov...The flashover of insulator strings occurring at normal working voltages undercontaminated/polluted conditions, obviously deserves serious consideration. Though much researchhas been gone into pollution-induced flashover phenomena but grey areas still exist in ourknowledge. In the present experimental study the breakdown (flashover) voltages across gaps oninsulator top surfaces and gaps between sheds (on the underside of an insulator), also the flashoverstudies on a single unit and a 3-unit insulator strings were carried out. An attempt has been madeto correlate the values obtained for all the cases. From the present investigation it was found thatresistance measurement of individual units of a polluted 3-unit string before and after flashoverindicates that strongly differing resistances could be the cause of flashover of ceramic discinsulator strings.展开更多
We find an azimuthal-angle dependent approximate wave like solution to second order on a warped five-dimensional manifold with a self-gravitating U(1) scalar gauge field (cosmic string) on the brane using the multiple...We find an azimuthal-angle dependent approximate wave like solution to second order on a warped five-dimensional manifold with a self-gravitating U(1) scalar gauge field (cosmic string) on the brane using the multiple-scale method. The spectrum of the several orders of approximation show maxima of the energy distribution dependent on the azimuthal-angle and the winding numbers n of the subsequent orders of scalar field. This breakup of the quantized flux quanta does not lead to instability of the asymptotic wavelike solution, due to the suppression of the n-dependency in the energy mo-mentum tensor components by the warp factor. This effect is triggered by the contribution of the five dimensional Weyl tensor on the brane. This con-tribution can be understood as dark energy and can trigger the self-acceleration of the universe without the need of a cosmological constant. There is a striking relation between the symmetry breaking of the Higgs field described by the winding number and the SO(2) breaking of the axially symmetric configuration into a discrete subgroup of rotations about 180°. The discrete sequence of non-axially symmetric deviations, cancelled by the emission of gravitational waves in order to restore the SO(2) symmetry, triggers the pressure Tzz for discrete values of the azimuthal-angle. There can be a possible relation between the recently discovered angle-preferences of polarization axes of quasars on large scales and our theoretical predicted angle-dependency and can be an evidence for the existence of cosmic strings. The discovery of the increase of polarization rate in smaller subgroups of the several large-quasar groups (LQGs), the red shift dependency and the relative orientation of the spin axes with respect to the major axes of their host LQGs, point at a fractional azimuthal structure, were also found in our cosmic string model. This peculiar discontinuous large scale structure, i.e., polarizations directions of multiples of, for example, π/2 orπ/4, can be explained by the spectrum of azimuthal-angle dependent wavelike modes without the need of conventional density perturbations in standard 4D cosmological models. Carefully com-parison of the spectrum of extremal values of the first and second order φ-dependency and the distribution of the alignment of the quasar polarizations is necessary. This can be accomplished when more observational data become available.展开更多
China‟s growing engagement in various sectors in South Asia poses challenges to India‟s regional dominant position.China has started billions of dollars investment for infrastructure development,especially in those st...China‟s growing engagement in various sectors in South Asia poses challenges to India‟s regional dominant position.China has started billions of dollars investment for infrastructure development,especially in those states who are part of its Belt and Road initiatives(BRI).Indian scholars consider Beijing‟s Indian Ocean centric investment including sea port expansion as a policy of controlling India by creating„string of pearls,‟those small countries as a vital„pearl‟in this„string‟.On the contrary,China claims that it is not anything concerning security in South Asia;rather,she looks for economic gain as well as a win-win situation for all.Except for India,all countries of this region have already welcomed their participation in the BRI.In order to illustrate the opposite perceptions of India and China,the paper aims to explore either China‟s investment in the South Asian region is for its strategic gain or more economic expansions.I argue that China‟s growing influence in South Asia should not be considered as a strategy of„encirclement‟against India.Nevertheless,the article concludes here if New Delhi and Beijing is looking forward to making a success of BRI,it certainly will bring crucial geopolitical and economic gain.展开更多
We present the model of an anisotropic universe with string fluid as the source of matter within the framework of the scalar-tensor theory of gravitation. An exact solution of field equations is obtained by applying B...We present the model of an anisotropic universe with string fluid as the source of matter within the framework of the scalar-tensor theory of gravitation. An exact solution of field equations is obtained by applying Berman's law of variation to Hubble's parameter which yields a constant value of the deceleration parameter. The nature of classical potential is examined for the model under consideration. It has also been found that the massive strings dominate in the early universe and finally disap-pear from the universe. This is in agreement with current astronomical observations. The physical and dynamical properties of the model are also discussed.展开更多
The existence of strings has not yet been proven, but if a fermion is considered as being made up of two coupled strings, then the coupling between these two strings creates tension in the strings, and this tension is...The existence of strings has not yet been proven, but if a fermion is considered as being made up of two coupled strings, then the coupling between these two strings creates tension in the strings, and this tension is proportional to the coupling force via the Planck constant. This provides an explanation for the origin of the Planck constant.展开更多
The recently discovered alignment of quasar polarizations on very large scales could possibly be explained by considering cosmic strings on a warped five dimensional spacetime. Compact objects, such as cosmic strings,...The recently discovered alignment of quasar polarizations on very large scales could possibly be explained by considering cosmic strings on a warped five dimensional spacetime. Compact objects, such as cosmic strings, could have tremendous mass in the bulk, while their warped manifestations in the brane can be consistent with general relativity in 4D. The self-gravitating cosmic string induces gravitational wavelike disturbances which could have effects felt on the brane, i.e., the massive effective 4D modes (Kaluza-Klein modes) of the perturbative 5D graviton. This effect is amplified by the time dependent part of the warp factor. Due to this warp factor, disturbances don’t fade away during the expansion of the universe. From a nonlinear perturbation analysis it is found that the effective Einstein 4D equations on an axially symmetric spacetime, contain a “back-reaction” term on the righthand side caused by the projected 5D Weyl tensor and can act as a dark energy term. The propagation equations to first order for the metric components and scalar-gauge fields contain -dependent terms, so the approximate wave solutions are no longer axially symmetric. The disturbances, amplified by the warp factor, can possess extremal values for fixed polar angles. This could explain the two preferred polarization vectors mod .展开更多
EVER since Yang Yue got married six years ago, she has kept her husband, Liang Xiaoming, on a short financial leash, giving him about 2,500 yuan ($393) a month for his own personal use.
An instrumental soloist from Hangzhou tugs at Morocco’s heartstrings with her Chinese pipa ConCert performer Yu Lingling likes to point out that her hometown,Hangzhou,East China’s Zhejiang Province,was the star ting...An instrumental soloist from Hangzhou tugs at Morocco’s heartstrings with her Chinese pipa ConCert performer Yu Lingling likes to point out that her hometown,Hangzhou,East China’s Zhejiang Province,was the star ting point of the ancient Silk Road,a corridor of intercivilizational exchange.As if predestined by the place of her bir th,the ar tist took the ar t of cultural展开更多
The Double Take column looks at a single topic from an African and Chinese perspective. This month we discuss whether husbands should surrender their salary within a family or not.
A numerical method is proposed to simulate the transverse vibrations of a viscoelastic moving string constituted by an integral law. In the numerical computation, the Galerkin method based on the Hermite functions is ...A numerical method is proposed to simulate the transverse vibrations of a viscoelastic moving string constituted by an integral law. In the numerical computation, the Galerkin method based on the Hermite functions is applied to discretize the state variables, and the Runge- Kutta method is applied to solve the resulting differential-integral equation system. A linear iterative process is designed to compute the integral terms at each time step, which makes the numerical method more efficient and accurate. As examples, nonlinear parametric vibrations of an axially moving viscoelastic string are analyzed.展开更多
A computational technique is proposed for the Galerkin discretization of axially moving strings with geometric nonlinearity. The Galerkin discretization is based on the eigenfunctions of stationary strings. The discre...A computational technique is proposed for the Galerkin discretization of axially moving strings with geometric nonlinearity. The Galerkin discretization is based on the eigenfunctions of stationary strings. The discretized equations are simplified by regrouping nonlinear terms to reduce the computation work. The scheme can be easily implemented in the practical programming. Numerical results show the effectiveness of the technique. The results also highlight the feature of Galerkin's discretization of gyroscopic continua that the term number in Galerkin's discretization should be even. The technique is generalized from elastic strings to viscoelastic strings.展开更多
Several aspects related with Lorentz force are discussed in the light of the presence of vibrating strings. Strings are considered as a compact,?tension and viscosity-free incompressible liquid. The motion of a charge...Several aspects related with Lorentz force are discussed in the light of the presence of vibrating strings. Strings are considered as a compact,?tension and viscosity-free incompressible liquid. The motion of a charge particle, obviously, represents the “line of vortex” in the medium of fluid. The term (VXB) turns out to be the natural consequence of Vortex dynamics. The present investigation also reveals the nature of the magnetic field and explains why and how this additional term takes part in Lorentz force.展开更多
Based on the actual measured well depth, azimuth and oblique angles, a novel interpolation method to obtain the well axis is developed. The initial stress of drill string at the reference state consistent with well ax...Based on the actual measured well depth, azimuth and oblique angles, a novel interpolation method to obtain the well axis is developed. The initial stress of drill string at the reference state consistent with well axis can be obtained from the curvature and the tortuosity of well axis. By using the principle of virtual work, the formula to compute the equivalent load vector of the initial stress was derived. In the derivation,the natural (curvilinear) coordinate system was adopted since both the curvature and the tortuosity were generally not zero. A set of displacement functions fully reflecting the rigid body modes was used. Some basic concepts in the finite element analysis of drill string were clarified. It is hoped that the proposed method would offer a theoretical basis for handling the geometric nonlinear problem of the drill string in a 3-D larg edisplacement wellbore.展开更多
It is a starting point in string theory to assume that elementary particles are in fact rotating strings, and the final goal of the theory is a complete description of fundamental physics, including general relativity...It is a starting point in string theory to assume that elementary particles are in fact rotating strings, and the final goal of the theory is a complete description of fundamental physics, including general relativity. This paper is instead concerned with the reversed question: starting from general relativity, is there a good way to motivate why rotating strings should be more natural models for elementary particles than, say, spherical particles or point-particles? Also, the purpose here is not to motivate full string theory. For example, no hidden dimensions come into play, only the four usual ones, and strings are defined in a very simple geometric way. Rather, the focus is on investigating an interesting mathematical property, which implies that strings may have special features with respect to rotation which spherically symmetric particles have not. In particular, it turns out that in a certain sense rotating strings are simpler than non-rotating ones. This is a consequence of the indefinite metric, and the main result states that the curvature of a non-rotating string, as measured by the square of the scalar curvature, may be reduced by letting it rotate in an appropriate way. The calculations underlying this theorem are heavy and have partly been car-ried out using Mathematica, although in principle the essential theorem may not require super-human labour.展开更多
The creative forces of affects are considered to be a mysterious power within our immanence. Although creators exist like lonely islands and may be more vulnerable to poor health, it is problematic to draw an inferenc...The creative forces of affects are considered to be a mysterious power within our immanence. Although creators exist like lonely islands and may be more vulnerable to poor health, it is problematic to draw an inference that mental illness nourishes creativity. Artists, philosophers, and scientists have to struggle with chaos to create a new vision into their works. This paper argues that first, the creativity of affects is a mysterious power of our immanence, not nourished by pathology;second, the surreal images of curved and juxtaposed spaces by the artists resonate with the scientific experiments conducted by string physicists who propose the existence of multiverse with the possibility of 11-dimensional spaces. Therefore, the creators have shared the equally-important status as the singular beings in their different modes of lives. Deleuze’s and Guattari’s creative concepts of philosophy help improve the better understanding of the mysterious power of oceanic affects within our immanence. Thus, the general opinion that creativity and mental illness are infamously connected should be entirely re-questioned and re-examined.展开更多
THE quote in the left is an extract taken from the Song of the Pipa,a classic poem written in the year 816 by the well-known Chinese poet Bai Juyi.One day when travelling down the Yangtze River on a boat,he suddenly h...THE quote in the left is an extract taken from the Song of the Pipa,a classic poem written in the year 816 by the well-known Chinese poet Bai Juyi.One day when travelling down the Yangtze River on a boat,he suddenly heard a captivating pipa melody wafting from afar.Greatly moved,Bai tried to trace the origin of the music and then found the pipa player,who had been a court pipa player when she was young.Putting on a soul-stirring pipa performance,the player seemingly intended to tell all of her joy in her prime and haplessness in the mid-life,which struck a chord with the poet who was then undergoing his own struggles.Greatly inspired,Bai penned the Song of the Pipa,which is now recognized as a masterpiece poem.The few lines from this poem provide an elaborate and vivid description of the abundant timbre of the pipa,a four-stringed Chinese musical instrument.展开更多
文摘Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism which is proportional to Planck’s constant. This may be the result of two massless bosons (hypergluons) coupled by a preon (prequark) exchange. It also gives a physical explanation to the origin of the Planck constant, and origin of spin.
基金supported by the National Natural Science Foundation of China(31272331 and 31470458 to HW,31472013 and 31772453 to WL)the Fundamental Research Funds for the Central Universities(2412016KJ043)the Open Project Program of Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization(130028685)
文摘Background: Birds produce alarm calls to convey information about threats. Some Passerine alarm calls consist of several note strings, but few studies have examined their function. Previous studies have shown that Japanese Tits(Parus minor) can alter the calling rate and number and combination of notes in response to predators. We previously found the combinations of note types in Japanese Tit alarm calls to be significantly different in response to the Sparrowhawk(Accipiter nisus) and Common Cuckoo(Cuculus canorus).Methods: Through playback experiments, we tested whether the note strings in Japanese Tit alarm calls to the Common Cuckoo have different functions in conveying information. The note strings of selected alarm calls were divided into the categories of C and D, and different calls were then constructed separately based on the two note string categories. Original alarm calls(C–D), C calls and D calls were played back to male Japanese Tits during the incubation period.Results: Male Japanese Tits had a significantly stronger response to C calls than to C–D calls, and they showed a significantly stronger response to both C and C–D calls than to D calls, suggesting that Japanese Tits discriminated between the C and D calls.Conclusions: Our study demonstrated that the C-and D-category note strings of Japanese Tit alarm calls to the Common Cuckoo have different functions, which supports the previous finding that different note strings in an alarm call can provide different information to receivers. However, the exact meanings of these note strings are not yet known, and further investigation is therefore required.
基金supported by the National Natural Science Foundation of China(10472021,10421002 and 10032030)the NSFC-RFBR Collaboration Project(1031120166/10411120494)the Scientific Research Foundation for the Retumed 0verseas Chinese Scholars,State Education Ministry.
文摘The Hamiltonian dynamics is adopted to solve the eigenvalue problem for transverse vibrations of axially moving strings. With the explicit Hamiltonian function the canonical equation of the free vibration is derived. Non-singular modal functions are obtained through a linear, symplectic eigenvalue analysis, and the symplectic-type orthogonality conditions of modes are derived. Stability of the transverse motion is examined by means of analyzing the eigenvalues and their bifurcation, especially for strings transporting with the critical speed. It is pointed out that the motion of the string does not possess divergence instability at the critical speed due to the weak interaction between eigenvalue pairs. The expansion theorem is applied with the non-singular modal functions to solve the displacement response to free and forced vibrations. It is demonstrated that the modal functions can be used as the base functions for solving linear and nonlinear vibration problems.
文摘The flashover of insulator strings occurring at normal working voltages undercontaminated/polluted conditions, obviously deserves serious consideration. Though much researchhas been gone into pollution-induced flashover phenomena but grey areas still exist in ourknowledge. In the present experimental study the breakdown (flashover) voltages across gaps oninsulator top surfaces and gaps between sheds (on the underside of an insulator), also the flashoverstudies on a single unit and a 3-unit insulator strings were carried out. An attempt has been madeto correlate the values obtained for all the cases. From the present investigation it was found thatresistance measurement of individual units of a polluted 3-unit string before and after flashoverindicates that strongly differing resistances could be the cause of flashover of ceramic discinsulator strings.
文摘We find an azimuthal-angle dependent approximate wave like solution to second order on a warped five-dimensional manifold with a self-gravitating U(1) scalar gauge field (cosmic string) on the brane using the multiple-scale method. The spectrum of the several orders of approximation show maxima of the energy distribution dependent on the azimuthal-angle and the winding numbers n of the subsequent orders of scalar field. This breakup of the quantized flux quanta does not lead to instability of the asymptotic wavelike solution, due to the suppression of the n-dependency in the energy mo-mentum tensor components by the warp factor. This effect is triggered by the contribution of the five dimensional Weyl tensor on the brane. This con-tribution can be understood as dark energy and can trigger the self-acceleration of the universe without the need of a cosmological constant. There is a striking relation between the symmetry breaking of the Higgs field described by the winding number and the SO(2) breaking of the axially symmetric configuration into a discrete subgroup of rotations about 180°. The discrete sequence of non-axially symmetric deviations, cancelled by the emission of gravitational waves in order to restore the SO(2) symmetry, triggers the pressure Tzz for discrete values of the azimuthal-angle. There can be a possible relation between the recently discovered angle-preferences of polarization axes of quasars on large scales and our theoretical predicted angle-dependency and can be an evidence for the existence of cosmic strings. The discovery of the increase of polarization rate in smaller subgroups of the several large-quasar groups (LQGs), the red shift dependency and the relative orientation of the spin axes with respect to the major axes of their host LQGs, point at a fractional azimuthal structure, were also found in our cosmic string model. This peculiar discontinuous large scale structure, i.e., polarizations directions of multiples of, for example, π/2 orπ/4, can be explained by the spectrum of azimuthal-angle dependent wavelike modes without the need of conventional density perturbations in standard 4D cosmological models. Carefully com-parison of the spectrum of extremal values of the first and second order φ-dependency and the distribution of the alignment of the quasar polarizations is necessary. This can be accomplished when more observational data become available.
文摘China‟s growing engagement in various sectors in South Asia poses challenges to India‟s regional dominant position.China has started billions of dollars investment for infrastructure development,especially in those states who are part of its Belt and Road initiatives(BRI).Indian scholars consider Beijing‟s Indian Ocean centric investment including sea port expansion as a policy of controlling India by creating„string of pearls,‟those small countries as a vital„pearl‟in this„string‟.On the contrary,China claims that it is not anything concerning security in South Asia;rather,she looks for economic gain as well as a win-win situation for all.Except for India,all countries of this region have already welcomed their participation in the BRI.In order to illustrate the opposite perceptions of India and China,the paper aims to explore either China‟s investment in the South Asian region is for its strategic gain or more economic expansions.I argue that China‟s growing influence in South Asia should not be considered as a strategy of„encirclement‟against India.Nevertheless,the article concludes here if New Delhi and Beijing is looking forward to making a success of BRI,it certainly will bring crucial geopolitical and economic gain.
文摘We present the model of an anisotropic universe with string fluid as the source of matter within the framework of the scalar-tensor theory of gravitation. An exact solution of field equations is obtained by applying Berman's law of variation to Hubble's parameter which yields a constant value of the deceleration parameter. The nature of classical potential is examined for the model under consideration. It has also been found that the massive strings dominate in the early universe and finally disap-pear from the universe. This is in agreement with current astronomical observations. The physical and dynamical properties of the model are also discussed.
文摘The existence of strings has not yet been proven, but if a fermion is considered as being made up of two coupled strings, then the coupling between these two strings creates tension in the strings, and this tension is proportional to the coupling force via the Planck constant. This provides an explanation for the origin of the Planck constant.
文摘The recently discovered alignment of quasar polarizations on very large scales could possibly be explained by considering cosmic strings on a warped five dimensional spacetime. Compact objects, such as cosmic strings, could have tremendous mass in the bulk, while their warped manifestations in the brane can be consistent with general relativity in 4D. The self-gravitating cosmic string induces gravitational wavelike disturbances which could have effects felt on the brane, i.e., the massive effective 4D modes (Kaluza-Klein modes) of the perturbative 5D graviton. This effect is amplified by the time dependent part of the warp factor. Due to this warp factor, disturbances don’t fade away during the expansion of the universe. From a nonlinear perturbation analysis it is found that the effective Einstein 4D equations on an axially symmetric spacetime, contain a “back-reaction” term on the righthand side caused by the projected 5D Weyl tensor and can act as a dark energy term. The propagation equations to first order for the metric components and scalar-gauge fields contain -dependent terms, so the approximate wave solutions are no longer axially symmetric. The disturbances, amplified by the warp factor, can possess extremal values for fixed polar angles. This could explain the two preferred polarization vectors mod .
文摘EVER since Yang Yue got married six years ago, she has kept her husband, Liang Xiaoming, on a short financial leash, giving him about 2,500 yuan ($393) a month for his own personal use.
文摘An instrumental soloist from Hangzhou tugs at Morocco’s heartstrings with her Chinese pipa ConCert performer Yu Lingling likes to point out that her hometown,Hangzhou,East China’s Zhejiang Province,was the star ting point of the ancient Silk Road,a corridor of intercivilizational exchange.As if predestined by the place of her bir th,the ar tist took the ar t of cultural
文摘The Double Take column looks at a single topic from an African and Chinese perspective. This month we discuss whether husbands should surrender their salary within a family or not.
基金supported by the National Outstanding Young Scientists Fund of China (No. 10725209)the National ScienceFoundation of China (No. 10672092)+1 种基金Shanghai Municipal Education Commission Scientific Research Project (No. 07ZZ07)Shanghai Leading Academic Discipline Project (No. Y0103).
文摘A numerical method is proposed to simulate the transverse vibrations of a viscoelastic moving string constituted by an integral law. In the numerical computation, the Galerkin method based on the Hermite functions is applied to discretize the state variables, and the Runge- Kutta method is applied to solve the resulting differential-integral equation system. A linear iterative process is designed to compute the integral terms at each time step, which makes the numerical method more efficient and accurate. As examples, nonlinear parametric vibrations of an axially moving viscoelastic string are analyzed.
基金supported by the National Outstanding Young Scientists Fund of China(No.10725209)the National Natural Science Foundation of China(No.10672092)+3 种基金Shanghai Subject Chief Scientist Project(No.09XD1401700)Shanghai Municipal Education Commission Scientific Research Project(No.07ZZ07)Shanghai Leading Academic Discipline Project (No.S30106)Changjiang Scholars and Innovative Research Team in University Program(No.IRT0844).
文摘A computational technique is proposed for the Galerkin discretization of axially moving strings with geometric nonlinearity. The Galerkin discretization is based on the eigenfunctions of stationary strings. The discretized equations are simplified by regrouping nonlinear terms to reduce the computation work. The scheme can be easily implemented in the practical programming. Numerical results show the effectiveness of the technique. The results also highlight the feature of Galerkin's discretization of gyroscopic continua that the term number in Galerkin's discretization should be even. The technique is generalized from elastic strings to viscoelastic strings.
文摘Several aspects related with Lorentz force are discussed in the light of the presence of vibrating strings. Strings are considered as a compact,?tension and viscosity-free incompressible liquid. The motion of a charge particle, obviously, represents the “line of vortex” in the medium of fluid. The term (VXB) turns out to be the natural consequence of Vortex dynamics. The present investigation also reveals the nature of the magnetic field and explains why and how this additional term takes part in Lorentz force.
文摘Based on the actual measured well depth, azimuth and oblique angles, a novel interpolation method to obtain the well axis is developed. The initial stress of drill string at the reference state consistent with well axis can be obtained from the curvature and the tortuosity of well axis. By using the principle of virtual work, the formula to compute the equivalent load vector of the initial stress was derived. In the derivation,the natural (curvilinear) coordinate system was adopted since both the curvature and the tortuosity were generally not zero. A set of displacement functions fully reflecting the rigid body modes was used. Some basic concepts in the finite element analysis of drill string were clarified. It is hoped that the proposed method would offer a theoretical basis for handling the geometric nonlinear problem of the drill string in a 3-D larg edisplacement wellbore.
文摘It is a starting point in string theory to assume that elementary particles are in fact rotating strings, and the final goal of the theory is a complete description of fundamental physics, including general relativity. This paper is instead concerned with the reversed question: starting from general relativity, is there a good way to motivate why rotating strings should be more natural models for elementary particles than, say, spherical particles or point-particles? Also, the purpose here is not to motivate full string theory. For example, no hidden dimensions come into play, only the four usual ones, and strings are defined in a very simple geometric way. Rather, the focus is on investigating an interesting mathematical property, which implies that strings may have special features with respect to rotation which spherically symmetric particles have not. In particular, it turns out that in a certain sense rotating strings are simpler than non-rotating ones. This is a consequence of the indefinite metric, and the main result states that the curvature of a non-rotating string, as measured by the square of the scalar curvature, may be reduced by letting it rotate in an appropriate way. The calculations underlying this theorem are heavy and have partly been car-ried out using Mathematica, although in principle the essential theorem may not require super-human labour.
文摘The creative forces of affects are considered to be a mysterious power within our immanence. Although creators exist like lonely islands and may be more vulnerable to poor health, it is problematic to draw an inference that mental illness nourishes creativity. Artists, philosophers, and scientists have to struggle with chaos to create a new vision into their works. This paper argues that first, the creativity of affects is a mysterious power of our immanence, not nourished by pathology;second, the surreal images of curved and juxtaposed spaces by the artists resonate with the scientific experiments conducted by string physicists who propose the existence of multiverse with the possibility of 11-dimensional spaces. Therefore, the creators have shared the equally-important status as the singular beings in their different modes of lives. Deleuze’s and Guattari’s creative concepts of philosophy help improve the better understanding of the mysterious power of oceanic affects within our immanence. Thus, the general opinion that creativity and mental illness are infamously connected should be entirely re-questioned and re-examined.
文摘THE quote in the left is an extract taken from the Song of the Pipa,a classic poem written in the year 816 by the well-known Chinese poet Bai Juyi.One day when travelling down the Yangtze River on a boat,he suddenly heard a captivating pipa melody wafting from afar.Greatly moved,Bai tried to trace the origin of the music and then found the pipa player,who had been a court pipa player when she was young.Putting on a soul-stirring pipa performance,the player seemingly intended to tell all of her joy in her prime and haplessness in the mid-life,which struck a chord with the poet who was then undergoing his own struggles.Greatly inspired,Bai penned the Song of the Pipa,which is now recognized as a masterpiece poem.The few lines from this poem provide an elaborate and vivid description of the abundant timbre of the pipa,a four-stringed Chinese musical instrument.