AIM： TO re-evaluate the recent clinicopathological fea- tures of remnant gastric cancer （RGC） and to develop desirable surveillance programs.METHODS： Between 1997 and 2008, 1149 patients underwent gastrectomy for ...AIM： TO re-evaluate the recent clinicopathological fea- tures of remnant gastric cancer （RGC） and to develop desirable surveillance programs.METHODS： Between 1997 and 2008, 1149 patients underwent gastrectomy for gastric cancer at the Department of Digestive Surgery, Kyoto Prefectural Uni- versity of Medicine, Japan. Of these, 33 patients un- derwent gastrectomy with lymphadenectomy for RGC. Regarding the initial gastric disease, there were 19 patients with benign disease and 14 patients with gas- tric cancer. The hospital records of these patients were reviewed retrospectively. RESULTS： Concerning the initial gastric disease, the RGC group following gastric cancer had a shorter in- terval [P 〈 0.05; gastric cancer vs benign disease： 12 （2-22） vs 30 （4-51） years] and were more frequently reconstructed by Billroth- I procedure than those fol- lowing benign lesions （P 〈 0.001）. Regarding recon- struction, RGC following Billroth-]_l reconstruction showed a longer interval between surgical procedures [P 〈 0.001; Billroth-11 vs Billroth- I ： 32 （5-51） vs 12 （2-36） years] and tumors were more frequently associated with benign disease （P 〈 0.001） than those following Billroth- I reconstruction. In tumor location of RGC, after Billroth- I reconstruction, RGC occurred more fre- quently near the suture line and remnant gastric wall. After Billroth- 1I reconstruction, RGC occurred more fre- quently at the anastomotic site. The duration of follow- up was significantly associated with the stage of RGC （P 〈 0.05）. Patients diagnosed with early stage RGC such as stage Ⅰ-Ⅱ tended to have been followed up almost every second year. CONCLUSION： Meticulous follow-up examination and early detection of RGC might lead to a better prognosis. Based on the initial gastric disease and the procedure of reconstruction, an appropriate follow-up interval and programs might enable early detection of RGC.展开更多
A wideband dipole signal is required for dipole dispersion correction and nearborehole imaging. To obtain the broadband flexural wave dispersion, we use a nonlinear frequency modulation （NLFM） signal and propose a s...A wideband dipole signal is required for dipole dispersion correction and nearborehole imaging. To obtain the broadband flexural wave dispersion, we use a nonlinear frequency modulation （NLFM） signal and propose a segment linear frequency modulation （SLFM） signal as the dipole excitation signal to compensate for the excitation intensity. The signal-to-noise ratio （SNR） of the signal over the entire frequency band is increased. The finite-difference method is used to simulate the responses from a Ricker wavelet, a linear frequency modulation （LFM） signal, an NLFM signal, and an SLFM signal in two borehole models of a homogeneously hard formation and a radially stratified formation. The dispersion and radial tomography results at low SNR of the sound source signals are compared. Numerical modeling suggests that the energy of the flexural waves excited by the Ricker wavelet source is concentrated near the Airy phase. In this case, the dispersion is incomplete and information regarding the formation near or far from the borehole cannot be obtained. The LFM signal yields dispersion information near the Airy phase and the high-frequency range but not in the low-frequency range. Moreover, the information regarding the formation far from the borehole is not accurate. The NLFM signal extends the frequency range of the flexural waves by compensating for the excitation intensity and yields information regarding the formation information, but it is not easy to obtain. The SLFM signal yields the same results as the NLFM signal and is easier to implement. Consequently, the dipole detection range expands and the S-wave velocity calculation accuracy improves.展开更多
In order to decrease relative settlement, foundation treatment plays an extremely important role in bridgehead transition section, especially, the situation of building the bridge piles firstly, and then processing pi...In order to decrease relative settlement, foundation treatment plays an extremely important role in bridgehead transition section, especially, the situation of building the bridge piles firstly, and then processing piles. On the basis of engineering practice, the authors analyzed the influence of foundation treatment on bridge piles in bridgehead transition section by finite-element method (FEM). This research has positive significance in predicting displacement of bridge pile, directing construction of foundation treatment, and improving quality of engineering and so forth.展开更多
A comparative study of two pre-stressed girder bridges, one with AASHTO （American Association of State Highway and Transportation Officials） Type III girders and the other with new FIB （Florida l-beam） girders, is...A comparative study of two pre-stressed girder bridges, one with AASHTO （American Association of State Highway and Transportation Officials） Type III girders and the other with new FIB （Florida l-beam） girders, is presented. FIB girders are expected to provide increased lateral stiffness, higher load carrying capacity, cost-efficiency and better reliability. In this paper, the first bridge that is analyzed is a 3-span bridge designed with six AASHTO Type III girders, and the second bridge has four FIB girders with the same span length, width and girder depth. The bridges are analyzed for Florida state legal loads SU4 and C5. Both bridges are analyzed using a sophisticated finite element method. The deflections, moment envelopes, section capacity and live load rating of the two bridges are obtained and compared. FIB girders have higher vertical stiffness, higher section capacity providing higher load rating than the AASHTO girders.展开更多
We consider mixed finite elements for the plane elasticity system and the Stokes equation. For the unmodified Hellinger-Reissner formulation of elasticity in which the stress and displacement fields are the primary un...We consider mixed finite elements for the plane elasticity system and the Stokes equation. For the unmodified Hellinger-Reissner formulation of elasticity in which the stress and displacement fields are the primary unknowns, we derive two new nonconforming mixed finite elements of triangle type. Both elements use piecewise rigid motions to approximate the displacement and piecewise polynomial functions to approximate the stress, where no vertex degrees of freedom are involved. The two stress finite element spaces consist respectively of piecewise quadratic polynomials and piecewise cubic polynomials such that the divergence of each space restricted to a single simplex is contained in the corresponding displacement approximation space. We derive stability and optimal order approximation for the elements. We also give some numerical results to verify the theoretical results. For the Stokes equation, introducing the symmetric part of the gradient tensor of the velocity as a stress variable, we present a stress-velocity-pressure field Stokes system. We use some plane elasticity mixed finite elements, including the two elements we proposed, to approximate the stress and velocity fields, and use continuous piecewise polynomial functions to approximate the pressure with the gradient of the pressure approximation being in the corresponding velocity finite element spaces. We derive stability and convergence for these methods.展开更多
This paper proposes a weak Galerkin finite element method to solve incompressible quasi-Newtonian Stokes equations. We use piecewise polynomials of degrees k + 1(k 0) and k for the velocity and pressure in the interio...This paper proposes a weak Galerkin finite element method to solve incompressible quasi-Newtonian Stokes equations. We use piecewise polynomials of degrees k + 1(k 0) and k for the velocity and pressure in the interior of elements, respectively, and piecewise polynomials of degrees k and k + 1 for the boundary parts of the velocity and pressure, respectively. Wellposedness of the discrete scheme is established. The method yields a globally divergence-free velocity approximation. Optimal priori error estimates are derived for the velocity gradient and pressure approximations. Numerical results are provided to confirm the theoretical results.展开更多
The triangular linear finite elements on piecewise uniform grid for an elliptic problem in convex polygonal domain are discussed. Global superconvergence in discrete Hi-norm and global extrapolation in discrete L2-nor...The triangular linear finite elements on piecewise uniform grid for an elliptic problem in convex polygonal domain are discussed. Global superconvergence in discrete Hi-norm and global extrapolation in discrete L2-norm are proved. Based on these global estimates the conjugate gradient method （CG） is effective, which is applied to extrapolation cascadic multigrid method （EXCMG）. The numerical experiments show that EXCMG is of the global higher accuracy for both function and gradient.展开更多
In this paper,we investigate the superconvergence property of the numerical solution to a quadratic elliptic control problem by using mixed finite element methods.The state and co-state are approximated by the order k...In this paper,we investigate the superconvergence property of the numerical solution to a quadratic elliptic control problem by using mixed finite element methods.The state and co-state are approximated by the order k=1 Raviart-Thomas mixed finite element spaces and the control variable is approximated by piecewise constant functions.We prove the superconvergence error estimate of h3/2 in L2-norm between the approximated solution and the average L2 projection of the control.Moreover,by the postprocessing technique,a quadratic superconvergence result of the control is derived.展开更多
文摘AIM： TO re-evaluate the recent clinicopathological fea- tures of remnant gastric cancer （RGC） and to develop desirable surveillance programs.METHODS： Between 1997 and 2008, 1149 patients underwent gastrectomy for gastric cancer at the Department of Digestive Surgery, Kyoto Prefectural Uni- versity of Medicine, Japan. Of these, 33 patients un- derwent gastrectomy with lymphadenectomy for RGC. Regarding the initial gastric disease, there were 19 patients with benign disease and 14 patients with gas- tric cancer. The hospital records of these patients were reviewed retrospectively. RESULTS： Concerning the initial gastric disease, the RGC group following gastric cancer had a shorter in- terval [P 〈 0.05; gastric cancer vs benign disease： 12 （2-22） vs 30 （4-51） years] and were more frequently reconstructed by Billroth- I procedure than those fol- lowing benign lesions （P 〈 0.001）. Regarding recon- struction, RGC following Billroth-]_l reconstruction showed a longer interval between surgical procedures [P 〈 0.001; Billroth-11 vs Billroth- I ： 32 （5-51） vs 12 （2-36） years] and tumors were more frequently associated with benign disease （P 〈 0.001） than those following Billroth- I reconstruction. In tumor location of RGC, after Billroth- I reconstruction, RGC occurred more fre- quently near the suture line and remnant gastric wall. After Billroth- 1I reconstruction, RGC occurred more fre- quently at the anastomotic site. The duration of follow- up was significantly associated with the stage of RGC （P 〈 0.05）. Patients diagnosed with early stage RGC such as stage Ⅰ-Ⅱ tended to have been followed up almost every second year. CONCLUSION： Meticulous follow-up examination and early detection of RGC might lead to a better prognosis. Based on the initial gastric disease and the procedure of reconstruction, an appropriate follow-up interval and programs might enable early detection of RGC.
基金This work was supported by the National Natural Science Foundation of China （Nos. 11574347, 11734017, 91630308, and 11374322）, the Youth Talent Project of the Institute of Acoustics of Chinese Academy of Sciences （No. QNYC201619）, and the PetroChina Innovation Foundation （No. 2016D-5007-0304）.
文摘A wideband dipole signal is required for dipole dispersion correction and nearborehole imaging. To obtain the broadband flexural wave dispersion, we use a nonlinear frequency modulation （NLFM） signal and propose a segment linear frequency modulation （SLFM） signal as the dipole excitation signal to compensate for the excitation intensity. The signal-to-noise ratio （SNR） of the signal over the entire frequency band is increased. The finite-difference method is used to simulate the responses from a Ricker wavelet, a linear frequency modulation （LFM） signal, an NLFM signal, and an SLFM signal in two borehole models of a homogeneously hard formation and a radially stratified formation. The dispersion and radial tomography results at low SNR of the sound source signals are compared. Numerical modeling suggests that the energy of the flexural waves excited by the Ricker wavelet source is concentrated near the Airy phase. In this case, the dispersion is incomplete and information regarding the formation near or far from the borehole cannot be obtained. The LFM signal yields dispersion information near the Airy phase and the high-frequency range but not in the low-frequency range. Moreover, the information regarding the formation far from the borehole is not accurate. The NLFM signal extends the frequency range of the flexural waves by compensating for the excitation intensity and yields information regarding the formation information, but it is not easy to obtain. The SLFM signal yields the same results as the NLFM signal and is easier to implement. Consequently, the dipole detection range expands and the S-wave velocity calculation accuracy improves.
文摘In order to decrease relative settlement, foundation treatment plays an extremely important role in bridgehead transition section, especially, the situation of building the bridge piles firstly, and then processing piles. On the basis of engineering practice, the authors analyzed the influence of foundation treatment on bridge piles in bridgehead transition section by finite-element method (FEM). This research has positive significance in predicting displacement of bridge pile, directing construction of foundation treatment, and improving quality of engineering and so forth.
文摘A comparative study of two pre-stressed girder bridges, one with AASHTO （American Association of State Highway and Transportation Officials） Type III girders and the other with new FIB （Florida l-beam） girders, is presented. FIB girders are expected to provide increased lateral stiffness, higher load carrying capacity, cost-efficiency and better reliability. In this paper, the first bridge that is analyzed is a 3-span bridge designed with six AASHTO Type III girders, and the second bridge has four FIB girders with the same span length, width and girder depth. The bridges are analyzed for Florida state legal loads SU4 and C5. Both bridges are analyzed using a sophisticated finite element method. The deflections, moment envelopes, section capacity and live load rating of the two bridges are obtained and compared. FIB girders have higher vertical stiffness, higher section capacity providing higher load rating than the AASHTO girders.
基金supported in part by National Natural Science Foundation of China (GrantNo. 10771150)the National Basic Research Program of China (Grant No. 2005CB321701)the program for New Century Excellent Talents in Universities (Grant No. NCET-07-0584)
文摘We consider mixed finite elements for the plane elasticity system and the Stokes equation. For the unmodified Hellinger-Reissner formulation of elasticity in which the stress and displacement fields are the primary unknowns, we derive two new nonconforming mixed finite elements of triangle type. Both elements use piecewise rigid motions to approximate the displacement and piecewise polynomial functions to approximate the stress, where no vertex degrees of freedom are involved. The two stress finite element spaces consist respectively of piecewise quadratic polynomials and piecewise cubic polynomials such that the divergence of each space restricted to a single simplex is contained in the corresponding displacement approximation space. We derive stability and optimal order approximation for the elements. We also give some numerical results to verify the theoretical results. For the Stokes equation, introducing the symmetric part of the gradient tensor of the velocity as a stress variable, we present a stress-velocity-pressure field Stokes system. We use some plane elasticity mixed finite elements, including the two elements we proposed, to approximate the stress and velocity fields, and use continuous piecewise polynomial functions to approximate the pressure with the gradient of the pressure approximation being in the corresponding velocity finite element spaces. We derive stability and convergence for these methods.
基金supported by Major Research Plan of National Natural Science Foundation of China (Grant No. 91430105)
文摘This paper proposes a weak Galerkin finite element method to solve incompressible quasi-Newtonian Stokes equations. We use piecewise polynomials of degrees k + 1(k 0) and k for the velocity and pressure in the interior of elements, respectively, and piecewise polynomials of degrees k and k + 1 for the boundary parts of the velocity and pressure, respectively. Wellposedness of the discrete scheme is established. The method yields a globally divergence-free velocity approximation. Optimal priori error estimates are derived for the velocity gradient and pressure approximations. Numerical results are provided to confirm the theoretical results.
基金supported by National Natural Science Foundation of China(Grant Nos.1130117611071067 and 11226332)+1 种基金the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120162120036)the Construct Program of the Key Discipline in Hunan Province
文摘The triangular linear finite elements on piecewise uniform grid for an elliptic problem in convex polygonal domain are discussed. Global superconvergence in discrete Hi-norm and global extrapolation in discrete L2-norm are proved. Based on these global estimates the conjugate gradient method （CG） is effective, which is applied to extrapolation cascadic multigrid method （EXCMG）. The numerical experiments show that EXCMG is of the global higher accuracy for both function and gradient.
基金supported by National Natural Science Foundation of China(Grant No.10971074)Foundation for Talent Introduction of Guangdong Provincial University,Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2008)Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20114407110009)
文摘In this paper,we investigate the superconvergence property of the numerical solution to a quadratic elliptic control problem by using mixed finite element methods.The state and co-state are approximated by the order k=1 Raviart-Thomas mixed finite element spaces and the control variable is approximated by piecewise constant functions.We prove the superconvergence error estimate of h3/2 in L2-norm between the approximated solution and the average L2 projection of the control.Moreover,by the postprocessing technique,a quadratic superconvergence result of the control is derived.
