We present a 1 × 4 Y-branch digital optical switch in which S-bend variable optical attenuators are integrated. The S-bend waveguides, which are always introduced to connect the switch and the standard fiber arra...We present a 1 × 4 Y-branch digital optical switch in which S-bend variable optical attenuators are integrated. The S-bend waveguides, which are always introduced to connect the switch and the standard fiber array, are made use of and designed as variable optical attenuators. A compact device with low crosstalk and larger branching-angle is obtained. The device is fabricated on the thermo-optic polymer materials,and the performance of the device is measured. With an applied driving power of less than 200mW, the device has a low crosstalk of less than - 35dB at a wavelength of 1.55 μm.展开更多
Rough set theory is a new mathematical tool to deal with vagneness and uncertainty. But original rough sets theory only generates deterministic rules and deals with data sets in which there is no noise. The variable p...Rough set theory is a new mathematical tool to deal with vagneness and uncertainty. But original rough sets theory only generates deterministic rules and deals with data sets in which there is no noise. The variable precision rough set model （VPRSM） is presented to handle uncertain and noisy information. A method based on VPRSM is proposed to apply to fault diagnosis feature extraction and rules acquisition for industrial applications. An example for fault diagnosis of rotary machinery is given to show that the method is very effective.展开更多
In this paper, the linear ordinary differential equations with variable coefficients are obtained from thecontrolling equations satisfied by wavelet transform or atmospheric internal gravity waves, and these linear eq...In this paper, the linear ordinary differential equations with variable coefficients are obtained from thecontrolling equations satisfied by wavelet transform or atmospheric internal gravity waves, and these linear equationscan be further transformed into Weber equations. From Weber equations, the homoclinic orbit solutions can be derived,so the solitary wave solutions to linear equations with variable coefficients are obtained.展开更多
A complete hydatidiform mole coexisting with a fetus following in vitro fertilization and embryo transfer (IVF-ET) is a rare event. The diagnosis is often not easy because of the morphological similarity to a partial ...A complete hydatidiform mole coexisting with a fetus following in vitro fertilization and embryo transfer (IVF-ET) is a rare event. The diagnosis is often not easy because of the morphological similarity to a partial mole, but important to the treatment. We present a recent case in which STR polymorphism analysis clearly revealed a different genetic origin for the fetal and molar parts. STR polymorphisms on 15 variable number tandem repeat loci and a gender-determination locus, which were detected by polymerase chain reaction, indicating that the cord/placenta and molar tissue were parental and androgenous, respectively. During follow-up, the patient developed persistent gestational trophoblastic tumor (GTT) which was successfully treated with chemotherapy. In this case, STR polymorphism analysis exactly diagnosed a twin pregnancy consisting of a complete hydatidiform mole and a fetus.展开更多
One of the advantages of the variational iteration method is the free choice of initial guess. In this paper we use the basic idea of the Jacobian-function method to construct a generalized trial function with some un...One of the advantages of the variational iteration method is the free choice of initial guess. In this paper we use the basic idea of the Jacobian-function method to construct a generalized trial function with some unknown parameters. The Jaulent-Miodek equations are used to illustrate effectiveness and convenience of this method, some new explicit exact travelling wave solutions have been obtained, which include bell-type soliton solution, kink-type soliton solutions, solitary wave solutions, and doubly periodic wave solutions.展开更多
By using the compatibility method, many explicit solutions of the (1+1)-dimensional variable-coefficientBroer-Kaup system are constructed, which include new solutions expressed by error function, Bessel function, expo...By using the compatibility method, many explicit solutions of the (1+1)-dimensional variable-coefficientBroer-Kaup system are constructed, which include new solutions expressed by error function, Bessel function, exponentialfunction, and Airy function.Some figures of the solutions are given by the symbolic computation system Maple.展开更多
This paper is to investigate a variable-coefficient modified Kortweg-de Vries （vc-mKdV） model, which describes some situations from fluid mechanics, ocean dynamics, and plasma mechanics. By the AblowRz-Kaup-NewellSe...This paper is to investigate a variable-coefficient modified Kortweg-de Vries （vc-mKdV） model, which describes some situations from fluid mechanics, ocean dynamics, and plasma mechanics. By the AblowRz-Kaup-NewellSegur procedure and symbolic computation, the Lax pair of the vc-MKdV model is derived. Then, based on the aforementioned Lax pair, the Darboux transformation is constructed and a new one-soliton-like solution is obtained as weft Features of the one-soliton-like solution are analyzed and graphically discussed to illustrate the influence of the variable coefficients in the solitonlike propagation.展开更多
A new method for calculating the failure probabilityof structures with random parameters is proposed based onmultivariate power polynomial expansion, in which te uncertain quantities include material properties, struc...A new method for calculating the failure probabilityof structures with random parameters is proposed based onmultivariate power polynomial expansion, in which te uncertain quantities include material properties, structuralgeometric characteristics and static loads. The structuralresponse is first expressed as a multivariable power polynomialexpansion, of which the coefficients ae then determined by utilizing the higher-order perturbation technique and Galerkinprojection scheme. Then, the final performance function ofthe structure is determined. Due to the explicitness of theperformance function, a multifold integral of the structuralfailure probability can be calculated directly by the Monte Carlo simulation, which only requires a smal amount ofcomputation time. Two numerical examples ae presented toillustate te accuracy ad efficiency of te proposed metiod. It is shown that compaed with the widely used first-orderreliability method （ FORM） and second-order reliabilitymethod （ SORM）, te results of the proposed method are closer to that of the direct Monte Carlo metiod,and it requires much less computational time.展开更多
Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum ...Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power.The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most.We presented a novel maximum power point tracking(MPPT)control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid.The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve,which had excellent dynamic and static performances and robustness.Simulation and experimental results testify the accuracy and validity of the control strategy.展开更多
The initial shear stress and plastic cohesion ( η ) are the most important parameters reflecting the rheological properties of the paste slurry. The rheological parameters as well as the quantitative relationship amo...The initial shear stress and plastic cohesion ( η ) are the most important parameters reflecting the rheological properties of the paste slurry. The rheological parameters as well as the quantitative relationship among the consumption of different fill materials were obtained through the experiment and research on these parameters. They can be used to predict the scope of the values of τ and η in production for a given ratio, which can reduce the conveying resistance of fill slurry along the pipelines and avoid the blockage of the pipelines. It is found that the rheological model of the total tailing slurry belongs to the Bingham type, which has a feature of strong internal structure and large initial shear stress. The calculation formula for the resistance loss of pipelines conforms nicely to the field test and the actual production in Jinchuan Nickel Mine.展开更多
Using every realization of the Virasoro-type symmetry algebra , we can obtain various high-dimensional integrable models under the meaning that they possess infinitely many symmetries. By means of a concrete realizati...Using every realization of the Virasoro-type symmetry algebra , we can obtain various high-dimensional integrable models under the meaning that they possess infinitely many symmetries. By means of a concrete realization, many -dimensional equations which possess Kac–Moody–Virasoro-type infinite dimensional symmetry algebras are obtained.展开更多
The present paper emphasizes the peristaltic mechanism of Rabinowitsch liquid in a complaint porous channel under the influence of variable liquid properties and convective heat transfer.The effect of inclination on t...The present paper emphasizes the peristaltic mechanism of Rabinowitsch liquid in a complaint porous channel under the influence of variable liquid properties and convective heat transfer.The effect of inclination on the complaint channel walls has been taken into account.The viscosity of the liquid varies across the thickness of the complaint channel,whereas,thermal conductivity varies concerning temperature.The nonlinear governing equations are solved by using perturbation technique under the long wavelength and small Reynold’s number approximations.The expressions for axial velocity,temperature,the coefficient of heat transfer and streamlines are obtained and analyzed graphically.The above said physiological phenomena are investigated for a specific set of relevant parameters on dilatant,Newtonian and pseudoplastic fluid models.The results presented here shows that the presence of variable viscosity,porous parameter and slip parameter significantly affects the flow quantities of dilatant,Newtonian and pseudoplastic fluid models.The investigation further reveals that an increase in the value of variable viscosity and porous parameters enhances the occurrence of trapping phenomenon.Moreover,the size of trapped bolus can be eliminated with suitably adjusting the angle of inclination parameter.展开更多
The new soliton solutions for the variable-coefficient Boussinesq system, whose applications are seen influid dynamics, are studied in this paper with symbolic computation. First, the Painleve analysis is used to inve...The new soliton solutions for the variable-coefficient Boussinesq system, whose applications are seen influid dynamics, are studied in this paper with symbolic computation. First, the Painleve analysis is used to investigateits integrability properties. For the identified case we give, the Lax pair of the system is found, and then the Darbouxtransformation is constructed. At last, some new soliton solutions are presented via the Darboux method. Those solutionsmight be of some value in fluid dynamics.展开更多
In this paper, hydrodynamic analysis of vertical axis tidal turbine （both fixed pitch ＆ variable pitch） is numerically analyzed. Two-dimensional numerical modeling ＆ simulation of the unsteady flow through the bla...In this paper, hydrodynamic analysis of vertical axis tidal turbine （both fixed pitch ＆ variable pitch） is numerically analyzed. Two-dimensional numerical modeling ＆ simulation of the unsteady flow through the blades of the turbine is performed using ANSYS CFX, hereafter CFX, which is based on a Reynolds-Averaged Navier-Stokes （RANS） model. A transient simulation is done for fixed pitch and variable pitch vertical axis tidal turbine using a Shear Stress Transport turbulence （SST） scheme. Main hydrodynamic parameters like torque T, combined moment CM, coefficients of performance Cp and coefficient of torque Cr, etc. are investigated. The modeling and meshing of turbine rotor is performed in ICEM-CFD. Moreover, the difference in meshing schemes between fixed pitch and variable pitch is also mentioned. Mesh motion option is employed for variable pitch turbine. This article is one part of the ongoing research on tm＇bine design and developments. The numerical simulation results are validated with well reputed analytical results performed by Edinburgh Design Ltd. The article concludes with a parametric study of turbine performance, comparison between fixed and variable pitch operation for a four-bladed turbine. It is found that for variable pitch we get maximum Ce and peak power at smaller revolution per minute N and tip sped ratio 2.展开更多
This study on the temporal and spatial variability of the viscosity and some chemical parameters in the sea surface microlayer (SML), the relationship between the viscosity and chemical parameters, and the influence o...This study on the temporal and spatial variability of the viscosity and some chemical parameters in the sea surface microlayer (SML), the relationship between the viscosity and chemical parameters, and the influence of the viscosity on the mass transfer coefficient ( K ) in the flux of materials through the air sea interface revealed that: The values of viscosity and some chemical parameters in the SML are higher than those in the sub surface layer (SSL), and at daytime are higher than those at night. The viscosity has positive corelation with chemical oxygen demand (COD), dissolved organic carbon (DOC) and salinity. The "SML effect" on K need not be considered because the SML effect on materials concentration is so small.展开更多
Lie symmetry reduction of some truly ＂variable coefficient＂ wave equations which are singled out from a class of （1 ＋ 1）-dimensional variable coefficient nonlinear wave equations with respect to one and two-dimen...Lie symmetry reduction of some truly ＂variable coefficient＂ wave equations which are singled out from a class of （1 ＋ 1）-dimensional variable coefficient nonlinear wave equations with respect to one and two-dimensional algebras is carried out. Some classes of exact solutions of the investigated equations are found by means of both the reductions and some modern techniques such as additional equivalent transformations and hidden symmetries and so on. Conditional symmetries are also discussed.展开更多
By use of a direct method, we discuss symmetries and reductions of the two-dimensional Burgers equation with variable coefficient (VCBurgers). Five types of symmetry-reducing VCBurgers to (1+1)-dimensional partial dif...By use of a direct method, we discuss symmetries and reductions of the two-dimensional Burgers equation with variable coefficient (VCBurgers). Five types of symmetry-reducing VCBurgers to (1+1)-dimensional partial differential equation and three types of symmetry reducing VCBurgers to ordinary differential equation are obtained.展开更多
文摘We present a 1 × 4 Y-branch digital optical switch in which S-bend variable optical attenuators are integrated. The S-bend waveguides, which are always introduced to connect the switch and the standard fiber array, are made use of and designed as variable optical attenuators. A compact device with low crosstalk and larger branching-angle is obtained. The device is fabricated on the thermo-optic polymer materials,and the performance of the device is measured. With an applied driving power of less than 200mW, the device has a low crosstalk of less than - 35dB at a wavelength of 1.55 μm.
基金Natural Scientific Research Project of the Education Department of Jiangsu Province in China(No.05KJB520048)
文摘Rough set theory is a new mathematical tool to deal with vagneness and uncertainty. But original rough sets theory only generates deterministic rules and deals with data sets in which there is no noise. The variable precision rough set model （VPRSM） is presented to handle uncertain and noisy information. A method based on VPRSM is proposed to apply to fault diagnosis feature extraction and rules acquisition for industrial applications. An example for fault diagnosis of rotary machinery is given to show that the method is very effective.
文摘In this paper, the linear ordinary differential equations with variable coefficients are obtained from thecontrolling equations satisfied by wavelet transform or atmospheric internal gravity waves, and these linear equationscan be further transformed into Weber equations. From Weber equations, the homoclinic orbit solutions can be derived,so the solitary wave solutions to linear equations with variable coefficients are obtained.
基金Supported by Production and Rresearch Projects of Guangdong Province (2007B090400140)
文摘A complete hydatidiform mole coexisting with a fetus following in vitro fertilization and embryo transfer (IVF-ET) is a rare event. The diagnosis is often not easy because of the morphological similarity to a partial mole, but important to the treatment. We present a recent case in which STR polymorphism analysis clearly revealed a different genetic origin for the fetal and molar parts. STR polymorphisms on 15 variable number tandem repeat loci and a gender-determination locus, which were detected by polymerase chain reaction, indicating that the cord/placenta and molar tissue were parental and androgenous, respectively. During follow-up, the patient developed persistent gestational trophoblastic tumor (GTT) which was successfully treated with chemotherapy. In this case, STR polymorphism analysis exactly diagnosed a twin pregnancy consisting of a complete hydatidiform mole and a fetus.
基金National Natural Science Foundation of China under Grant No.10172056
文摘One of the advantages of the variational iteration method is the free choice of initial guess. In this paper we use the basic idea of the Jacobian-function method to construct a generalized trial function with some unknown parameters. The Jaulent-Miodek equations are used to illustrate effectiveness and convenience of this method, some new explicit exact travelling wave solutions have been obtained, which include bell-type soliton solution, kink-type soliton solutions, solitary wave solutions, and doubly periodic wave solutions.
基金Supported by the Youth Nature Science Foundation of Anhui University of Technology in China under Grant No.QZ200823the Natural Science Foundation of the Anhui Higher Education Institutions of China under Grant No.KJ2010A043
文摘By using the compatibility method, many explicit solutions of the (1+1)-dimensional variable-coefficientBroer-Kaup system are constructed, which include new solutions expressed by error function, Bessel function, exponentialfunction, and Airy function.Some figures of the solutions are given by the symbolic computation system Maple.
基金Supported by the National Natural Science Foundation of China under Grant No. 60772023by the Open Fund of the State Key Laboratory of Software Development Environment under Grant No. BUAA-SKLSDE-09KF-04+1 种基金Beijing University of Aeronautics and Astronautics, by the National Basic Research Program of China (973 Program) under Grant No. 2005CB321901by the Specialized Research Fund for the Doctoral Program of Higher Education under Grant Nos. 20060006024 and 200800130006, Chinese Ministry of Education
文摘This paper is to investigate a variable-coefficient modified Kortweg-de Vries （vc-mKdV） model, which describes some situations from fluid mechanics, ocean dynamics, and plasma mechanics. By the AblowRz-Kaup-NewellSegur procedure and symbolic computation, the Lax pair of the vc-MKdV model is derived. Then, based on the aforementioned Lax pair, the Darboux transformation is constructed and a new one-soliton-like solution is obtained as weft Features of the one-soliton-like solution are analyzed and graphically discussed to illustrate the influence of the variable coefficients in the solitonlike propagation.
基金The National Natural Science Foundation of China(No.51378407,51578431)
文摘A new method for calculating the failure probabilityof structures with random parameters is proposed based onmultivariate power polynomial expansion, in which te uncertain quantities include material properties, structuralgeometric characteristics and static loads. The structuralresponse is first expressed as a multivariable power polynomialexpansion, of which the coefficients ae then determined by utilizing the higher-order perturbation technique and Galerkinprojection scheme. Then, the final performance function ofthe structure is determined. Due to the explicitness of theperformance function, a multifold integral of the structuralfailure probability can be calculated directly by the Monte Carlo simulation, which only requires a smal amount ofcomputation time. Two numerical examples ae presented toillustate te accuracy ad efficiency of te proposed metiod. It is shown that compaed with the widely used first-orderreliability method （ FORM） and second-order reliabilitymethod （ SORM）, te results of the proposed method are closer to that of the direct Monte Carlo metiod,and it requires much less computational time.
基金Funded by the National Natural Science Foundation of China(No.60974049)the Science and Technology Support Industrial Project of Jiangsu Province(No.BZ2008031,No.BE2008074,and No.BE2009090)+1 种基金the Nantong International Cooperative Project(No.W2009003)the Natural Science Foundation of Nantong University(No.08Z022 and No.08Z025).
文摘Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power.The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most.We presented a novel maximum power point tracking(MPPT)control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid.The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve,which had excellent dynamic and static performances and robustness.Simulation and experimental results testify the accuracy and validity of the control strategy.
文摘The initial shear stress and plastic cohesion ( η ) are the most important parameters reflecting the rheological properties of the paste slurry. The rheological parameters as well as the quantitative relationship among the consumption of different fill materials were obtained through the experiment and research on these parameters. They can be used to predict the scope of the values of τ and η in production for a given ratio, which can reduce the conveying resistance of fill slurry along the pipelines and avoid the blockage of the pipelines. It is found that the rheological model of the total tailing slurry belongs to the Bingham type, which has a feature of strong internal structure and large initial shear stress. The calculation formula for the resistance loss of pipelines conforms nicely to the field test and the actual production in Jinchuan Nickel Mine.
文摘Using every realization of the Virasoro-type symmetry algebra , we can obtain various high-dimensional integrable models under the meaning that they possess infinitely many symmetries. By means of a concrete realization, many -dimensional equations which possess Kac–Moody–Virasoro-type infinite dimensional symmetry algebras are obtained.
文摘The present paper emphasizes the peristaltic mechanism of Rabinowitsch liquid in a complaint porous channel under the influence of variable liquid properties and convective heat transfer.The effect of inclination on the complaint channel walls has been taken into account.The viscosity of the liquid varies across the thickness of the complaint channel,whereas,thermal conductivity varies concerning temperature.The nonlinear governing equations are solved by using perturbation technique under the long wavelength and small Reynold’s number approximations.The expressions for axial velocity,temperature,the coefficient of heat transfer and streamlines are obtained and analyzed graphically.The above said physiological phenomena are investigated for a specific set of relevant parameters on dilatant,Newtonian and pseudoplastic fluid models.The results presented here shows that the presence of variable viscosity,porous parameter and slip parameter significantly affects the flow quantities of dilatant,Newtonian and pseudoplastic fluid models.The investigation further reveals that an increase in the value of variable viscosity and porous parameters enhances the occurrence of trapping phenomenon.Moreover,the size of trapped bolus can be eliminated with suitably adjusting the angle of inclination parameter.
基金Supported by the National Natural Science Foundation of China under Grant No. 60772023the Open Fund of the State Key Laboratory of Software Development Environment under Grant No. BUAA-SKLSDE-09KF-04+1 种基金Beijing University of Aeronautics and Astronautics, by the National Basic Research Program of China (973 Program) under Grant No. 2005CB321901the Specialized Research Fund for the Doctoral Program of Higher Education under Grant Nos. 20060006024 and 200800130006, Chinese Ministry of Education
文摘The new soliton solutions for the variable-coefficient Boussinesq system, whose applications are seen influid dynamics, are studied in this paper with symbolic computation. First, the Painleve analysis is used to investigateits integrability properties. For the identified case we give, the Lax pair of the system is found, and then the Darbouxtransformation is constructed. At last, some new soliton solutions are presented via the Darboux method. Those solutionsmight be of some value in fluid dynamics.
基金financially supported by National "863" Program (Grant No.2007AA05Z450, No. 200805040)National S&T Program (No.2008BAA15B04)+2 种基金2010 National Ocean Special Funds(No.ZJME2010GC01, No. ZJME2010CY01, No.GHME2010GC02)supported by the Fundamental Research Funds of the Universities(No.HEUCF130105)supported by "111 project" foundation(No. B07019) from State Administration of Foreign Experts Affairs of China and Ministry of Education of China
文摘In this paper, hydrodynamic analysis of vertical axis tidal turbine （both fixed pitch ＆ variable pitch） is numerically analyzed. Two-dimensional numerical modeling ＆ simulation of the unsteady flow through the blades of the turbine is performed using ANSYS CFX, hereafter CFX, which is based on a Reynolds-Averaged Navier-Stokes （RANS） model. A transient simulation is done for fixed pitch and variable pitch vertical axis tidal turbine using a Shear Stress Transport turbulence （SST） scheme. Main hydrodynamic parameters like torque T, combined moment CM, coefficients of performance Cp and coefficient of torque Cr, etc. are investigated. The modeling and meshing of turbine rotor is performed in ICEM-CFD. Moreover, the difference in meshing schemes between fixed pitch and variable pitch is also mentioned. Mesh motion option is employed for variable pitch turbine. This article is one part of the ongoing research on tm＇bine design and developments. The numerical simulation results are validated with well reputed analytical results performed by Edinburgh Design Ltd. The article concludes with a parametric study of turbine performance, comparison between fixed and variable pitch operation for a four-bladed turbine. It is found that for variable pitch we get maximum Ce and peak power at smaller revolution per minute N and tip sped ratio 2.
文摘This study on the temporal and spatial variability of the viscosity and some chemical parameters in the sea surface microlayer (SML), the relationship between the viscosity and chemical parameters, and the influence of the viscosity on the mass transfer coefficient ( K ) in the flux of materials through the air sea interface revealed that: The values of viscosity and some chemical parameters in the SML are higher than those in the sub surface layer (SSL), and at daytime are higher than those at night. The viscosity has positive corelation with chemical oxygen demand (COD), dissolved organic carbon (DOC) and salinity. The "SML effect" on K need not be considered because the SML effect on materials concentration is so small.
基金Supported by the National Key Basic Research Project of China under Grant No.2010CB126600the National Natural Science Foundation of China under Grant No.60873070+2 种基金Shanghai Leading Academic Discipline Project No.B114the Postdoctoral Science Foundation of China under Grant No.20090450067Shanghai Postdoctoral Science Foundation under Grant No.09R21410600
文摘Lie symmetry reduction of some truly ＂variable coefficient＂ wave equations which are singled out from a class of （1 ＋ 1）-dimensional variable coefficient nonlinear wave equations with respect to one and two-dimensional algebras is carried out. Some classes of exact solutions of the investigated equations are found by means of both the reductions and some modern techniques such as additional equivalent transformations and hidden symmetries and so on. Conditional symmetries are also discussed.
文摘By use of a direct method, we discuss symmetries and reductions of the two-dimensional Burgers equation with variable coefficient (VCBurgers). Five types of symmetry-reducing VCBurgers to (1+1)-dimensional partial differential equation and three types of symmetry reducing VCBurgers to ordinary differential equation are obtained.
