In one step inverse finite element approach, an initial blank shape is normally predicted from the final deformed shape. The final deformed shape needs to be trimmed into a final part after stamping, the trimmed area,...In one step inverse finite element approach, an initial blank shape is normally predicted from the final deformed shape. The final deformed shape needs to be trimmed into a final part after stamping, the trimmed area, therefore, needs to be compensated manually before using one step inverse approach, which causes low efficiency and in consistency with the real situation. To solve this problem, one step positive approach is proposed to simulate the sheet metal stamping process. Firstly the spatial initial solution of one step positive method is preliminarily obtained by using the mapping relationship and area coordinates, then based on the deformation theory the iterative solving is carried out in three-dimensional coordinate system by using quasi-conjugate-gradient method. During iterative process the contact judgment method is introduced to ensure that the nodes on the spatial initial solution are not separated from die surface. The predicted results of sheet metal forming process that include the shape and thickness of the stamped part can be obtained after the iterative solving process. The validity of the proposed approach is verified by comparing the predicted results obtained through the proposed approach with those obtained through the module of one step inverse approach in Autoform and the real stamped part. In one step positive method, the stamped shape of regular sheet can be calculated fast and effectively. During the iterative solution, the quasi-conjugate-gradient method is proposed to take the place of solving system of equations, and it can improve the stability and precision of the algorithm.展开更多
BACKGROUND Total cervical artificial disc replacement(TDR)has been considered a safe and effective alternative surgical treatment for cervical spondylosis and degenerative disc disease that have failed to improve with...BACKGROUND Total cervical artificial disc replacement(TDR)has been considered a safe and effective alternative surgical treatment for cervical spondylosis and degenerative disc disease that have failed to improve with conservative methods.Positioning the surgical patient is a critical part of the procedure.Appropriate patient positioning is crucial not only for the safety of the patient but also for optimizing surgical exposure,ensuring adequate and safe anesthesia,and allowing the surgeon to operate comfortably during lengthy procedures.The surgical posture is the traditional position used in anterior cervical approach;in general,patients are in a supine position with a pad under their shoulders and a ring-shaped pillow under their head.AIM To investigate the clinical outcomes of the use of a modified surgical position versus the traditional surgical position in anterior approach for TDR.METHODS In the modified position group,the patients had a soft pillow under their neck,and their jaw and both shoulders were fixed with wide tape.The analyzed data included intraoperative blood loss,position setting time,total operation time,and perioperative blood pressure and heart rate.RESULTS Blood pressure and heart rate were not significantly different before and after body positioning in both groups(P>0.05).Compared with the traditional position group,the modified position group showed a statistically significantly longer position setting time(P<0.05).However,the total operation time and intraoperative blood loss were significantly reduced in the modified position group compared with the traditional position group(P<0.05).CONCLUSION The clinical outcomes indicated that total operation time and intraoperative blood loss were relatively lower in the modified position group than in the traditional position group,thus reducing the risks of surgery while increasing the position setting time.The modified surgical position is a safe and effective method to be used in anterior approach for TDR surgery.展开更多
The purpose of this paper is to combine the estimation of output price risk and positive mathematical programming (PMP). It reconciles the risk programming presented by Freund with a consistent estimate of the constan...The purpose of this paper is to combine the estimation of output price risk and positive mathematical programming (PMP). It reconciles the risk programming presented by Freund with a consistent estimate of the constant absolute risk aversion (CARA) coefficient. It extends the PMP approach to calibration of realized production outputs and observed input prices. The results of this specification include 1) uniqueness of the calibrating solution, 2) elimination of the tautological calibration constraints typical of the original PMP procedure, 3) equivalence between a phase I calibrating solution and a solution obtained by combining phase I and phase II of the traditional PMP procedure. In this extended PMP framework, the cost function specification involves output quantities and input prices—contrary to the myopic cost function of the traditional PMP approach. This extension allows for a phase III calibrating model that replaces the usual linear technology with relations corresponding to Shephard lemma (in the primal constraints) and the marginal cost function (in the dual constraints). An empirical example with a sample of farms producing four crops illustrates the novel procedure.展开更多
In this paper, we investigate the solvability of a class of semilinear elliptic equations which are perturbation of the problems involving critical Hardy-Sobolev exponent and Hardy singular terms. The existence of at ...In this paper, we investigate the solvability of a class of semilinear elliptic equations which are perturbation of the problems involving critical Hardy-Sobolev exponent and Hardy singular terms. The existence of at least a positive radial solution is established for a class of semilinear elliptic problems involving critical Hardy-Sobolev exponent and Hardy terms. The main tools are variational method, critical point theory and some analysis techniques.展开更多
AIM:To study our novel caudal approach laparoscopic posterior-sectionectomy with parenchymal transection prior to mobilization under laparoscopy-specific view.METHODS:Points of the procedure are:(1) Patients are put i...AIM:To study our novel caudal approach laparoscopic posterior-sectionectomy with parenchymal transection prior to mobilization under laparoscopy-specific view.METHODS:Points of the procedure are:(1) Patients are put in left lateral position and posterior sector is not mobilized;(2) Glissonian pedicle of the sector is encircled and clamped extra-hepatically and divided afterward during the transection;(3) Dissection of inferior vena cava(IVC) anterior wall behind the liver is started from caudal.Simultaneously,liver transection is performed to search right hepatic vein(RHV) from caudal;(4) Liver transection proceeds to the bifurcation of the vessels from caudal to cranial,exposing the surfaces of IVC and RHV.Since the remnant liver sinks down,the cutting surface is well-opend;and(5) After the completion of transection,dissection of the resected liver from retroperitoneum is easily performed using the gravity.This approach was performed for a 63 years old woman with liver metastasis close to RHV.RESULTS:RHV exposure is required for R0 resection of the lesion.Although the cutting plane is horizontal in supine position and the gravity obstructs the exposure in the small subphrenic space,the use of specific characteristics of laparoscopic hepatectomy,such as the good vision for the dorsal part of the liver and IVC and facilitated dissection using the gravity with the patient positioning,made the complete RHV exposure during the liver transection easy to perform.The operation time was 341 min and operative blood loss was 1356 mL.Her postoperative hospital stay was uneventfull and she is well without any signs of recurrences 14 mo after surgery.CONCLUSION:The new procedure is feasible and useful for the patients with tumors close to RHV and the need of the exposure of RHV.展开更多
In this paper,an efficient multi-step scheme is presented based on reproducing kernel Hilbert space(RKHS)theory for solving ordinary stiff differential systems.The solution methodology depends on reproducing kernel fu...In this paper,an efficient multi-step scheme is presented based on reproducing kernel Hilbert space(RKHS)theory for solving ordinary stiff differential systems.The solution methodology depends on reproducing kernel functions to obtain analytic solutions in a uniform formfor a rapidly convergent series in the posed Sobolev space.Using the Gram-Schmidt orthogonality process,complete orthogonal essential functions are obtained in a compact field to encompass Fourier series expansion with the help of kernel properties reproduction.Consequently,by applying the standard RKHS method to each subinterval,approximate solutions that converge uniformly to the exact solutions are obtained.For this purpose,several numerical examples are tested to show proposed algorithm’s superiority,simplicity,and efficiency.The gained results indicate that themulti-step RKHSmethod is suitable for solving linear and nonlinear stiffness systems over an extensive duration and giving highly accurate outcomes.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 51075187)
文摘In one step inverse finite element approach, an initial blank shape is normally predicted from the final deformed shape. The final deformed shape needs to be trimmed into a final part after stamping, the trimmed area, therefore, needs to be compensated manually before using one step inverse approach, which causes low efficiency and in consistency with the real situation. To solve this problem, one step positive approach is proposed to simulate the sheet metal stamping process. Firstly the spatial initial solution of one step positive method is preliminarily obtained by using the mapping relationship and area coordinates, then based on the deformation theory the iterative solving is carried out in three-dimensional coordinate system by using quasi-conjugate-gradient method. During iterative process the contact judgment method is introduced to ensure that the nodes on the spatial initial solution are not separated from die surface. The predicted results of sheet metal forming process that include the shape and thickness of the stamped part can be obtained after the iterative solving process. The validity of the proposed approach is verified by comparing the predicted results obtained through the proposed approach with those obtained through the module of one step inverse approach in Autoform and the real stamped part. In one step positive method, the stamped shape of regular sheet can be calculated fast and effectively. During the iterative solution, the quasi-conjugate-gradient method is proposed to take the place of solving system of equations, and it can improve the stability and precision of the algorithm.
文摘BACKGROUND Total cervical artificial disc replacement(TDR)has been considered a safe and effective alternative surgical treatment for cervical spondylosis and degenerative disc disease that have failed to improve with conservative methods.Positioning the surgical patient is a critical part of the procedure.Appropriate patient positioning is crucial not only for the safety of the patient but also for optimizing surgical exposure,ensuring adequate and safe anesthesia,and allowing the surgeon to operate comfortably during lengthy procedures.The surgical posture is the traditional position used in anterior cervical approach;in general,patients are in a supine position with a pad under their shoulders and a ring-shaped pillow under their head.AIM To investigate the clinical outcomes of the use of a modified surgical position versus the traditional surgical position in anterior approach for TDR.METHODS In the modified position group,the patients had a soft pillow under their neck,and their jaw and both shoulders were fixed with wide tape.The analyzed data included intraoperative blood loss,position setting time,total operation time,and perioperative blood pressure and heart rate.RESULTS Blood pressure and heart rate were not significantly different before and after body positioning in both groups(P>0.05).Compared with the traditional position group,the modified position group showed a statistically significantly longer position setting time(P<0.05).However,the total operation time and intraoperative blood loss were significantly reduced in the modified position group compared with the traditional position group(P<0.05).CONCLUSION The clinical outcomes indicated that total operation time and intraoperative blood loss were relatively lower in the modified position group than in the traditional position group,thus reducing the risks of surgery while increasing the position setting time.The modified surgical position is a safe and effective method to be used in anterior approach for TDR surgery.
文摘The purpose of this paper is to combine the estimation of output price risk and positive mathematical programming (PMP). It reconciles the risk programming presented by Freund with a consistent estimate of the constant absolute risk aversion (CARA) coefficient. It extends the PMP approach to calibration of realized production outputs and observed input prices. The results of this specification include 1) uniqueness of the calibrating solution, 2) elimination of the tautological calibration constraints typical of the original PMP procedure, 3) equivalence between a phase I calibrating solution and a solution obtained by combining phase I and phase II of the traditional PMP procedure. In this extended PMP framework, the cost function specification involves output quantities and input prices—contrary to the myopic cost function of the traditional PMP approach. This extension allows for a phase III calibrating model that replaces the usual linear technology with relations corresponding to Shephard lemma (in the primal constraints) and the marginal cost function (in the dual constraints). An empirical example with a sample of farms producing four crops illustrates the novel procedure.
文摘In this paper, we investigate the solvability of a class of semilinear elliptic equations which are perturbation of the problems involving critical Hardy-Sobolev exponent and Hardy singular terms. The existence of at least a positive radial solution is established for a class of semilinear elliptic problems involving critical Hardy-Sobolev exponent and Hardy terms. The main tools are variational method, critical point theory and some analysis techniques.
文摘AIM:To study our novel caudal approach laparoscopic posterior-sectionectomy with parenchymal transection prior to mobilization under laparoscopy-specific view.METHODS:Points of the procedure are:(1) Patients are put in left lateral position and posterior sector is not mobilized;(2) Glissonian pedicle of the sector is encircled and clamped extra-hepatically and divided afterward during the transection;(3) Dissection of inferior vena cava(IVC) anterior wall behind the liver is started from caudal.Simultaneously,liver transection is performed to search right hepatic vein(RHV) from caudal;(4) Liver transection proceeds to the bifurcation of the vessels from caudal to cranial,exposing the surfaces of IVC and RHV.Since the remnant liver sinks down,the cutting surface is well-opend;and(5) After the completion of transection,dissection of the resected liver from retroperitoneum is easily performed using the gravity.This approach was performed for a 63 years old woman with liver metastasis close to RHV.RESULTS:RHV exposure is required for R0 resection of the lesion.Although the cutting plane is horizontal in supine position and the gravity obstructs the exposure in the small subphrenic space,the use of specific characteristics of laparoscopic hepatectomy,such as the good vision for the dorsal part of the liver and IVC and facilitated dissection using the gravity with the patient positioning,made the complete RHV exposure during the liver transection easy to perform.The operation time was 341 min and operative blood loss was 1356 mL.Her postoperative hospital stay was uneventfull and she is well without any signs of recurrences 14 mo after surgery.CONCLUSION:The new procedure is feasible and useful for the patients with tumors close to RHV and the need of the exposure of RHV.
文摘In this paper,an efficient multi-step scheme is presented based on reproducing kernel Hilbert space(RKHS)theory for solving ordinary stiff differential systems.The solution methodology depends on reproducing kernel functions to obtain analytic solutions in a uniform formfor a rapidly convergent series in the posed Sobolev space.Using the Gram-Schmidt orthogonality process,complete orthogonal essential functions are obtained in a compact field to encompass Fourier series expansion with the help of kernel properties reproduction.Consequently,by applying the standard RKHS method to each subinterval,approximate solutions that converge uniformly to the exact solutions are obtained.For this purpose,several numerical examples are tested to show proposed algorithm’s superiority,simplicity,and efficiency.The gained results indicate that themulti-step RKHSmethod is suitable for solving linear and nonlinear stiffness systems over an extensive duration and giving highly accurate outcomes.
