目的探讨第三脑室底造瘘(endoscopic third ventriculostomy,ETV)治疗非交通性脑积水失败的原因和防治方法。方法回顾性分析2例ETV术后造瘘口闭塞的非交通性脑积水病人的临床资料,结合文献复习分析ETV失败的原因,并提出相应的防治方法...目的探讨第三脑室底造瘘(endoscopic third ventriculostomy,ETV)治疗非交通性脑积水失败的原因和防治方法。方法回顾性分析2例ETV术后造瘘口闭塞的非交通性脑积水病人的临床资料,结合文献复习分析ETV失败的原因,并提出相应的防治方法。结果内镜直视下发现2种不同的瘘口闭塞模式,经2次造瘘和分流术治疗,病人临床症状均明显好转。结论造瘘口和远端脑池的梗阻可能是ETV治疗非交通性脑积水术后失败的重要原因,2次手术时应在内镜直视下探查造瘘口,而保持足够大的造瘘口并合理处理是预防瘘口闭塞的有效手段之一。展开更多
In dense wavelength division multiplexing(DWDM) optical transmission systems, cross phase modulation(XPM) due to Kerr effect causes phase shift and intensity modulation in each channel, which will lead the channel cap...In dense wavelength division multiplexing(DWDM) optical transmission systems, cross phase modulation(XPM) due to Kerr effect causes phase shift and intensity modulation in each channel, which will lead the channel capacity to be a random variable. An expression of the channel capacity dealing with XPM effect is presented, and the correctness and accuracy of this method are demonstrated by numerical simulation.展开更多
By handling the travel cost function artfully, the authors formulate the transportation mixed network design problem （MNDP） as a mixed-integer, nonlinear bilevel programming problem, in which the lower-level problem...By handling the travel cost function artfully, the authors formulate the transportation mixed network design problem （MNDP） as a mixed-integer, nonlinear bilevel programming problem, in which the lower-level problem, comparing with that of conventional bilevel DNDP models, is not a side constrained user equilibrium assignment problem, but a standard user equilibrium assignment problem. Then, the bilevel programming model for MNDP is reformulated as a continuous version of bilevel programming problem by the continuation method. By virtue of the optimal-value function, the lower-level assignment problem can be expressed as a nonlinear equality constraint. Therefore, the bilevel programming model for MNDP can be transformed into an equivalent single-level optimization problem. By exploring the inherent nature of the MNDP, the optimal-value function for the lower- level equilibrium assignment problem is proved to be continuously differentiable and its functional value and gradient can be obtained efficiently. Thus, a continuously differentiable but still nonconvex optimization formulation of the MNDP is created, and then a locally convergent algorithm is proposed by applying penalty function method. The inner loop of solving the subproblem is mainly to implement an Ml-or-nothing assignment. Finally, a small-scale transportation network and a large-scale network are presented to verify the proposed model and algorithm.展开更多
This paper presents a unified bination algorithms （such as FrankWolfe problems. Global convergence results are framework of the nonmonotone convex comAlgorithm） for solving the traffic assignment established under m...This paper presents a unified bination algorithms （such as FrankWolfe problems. Global convergence results are framework of the nonmonotone convex comAlgorithm） for solving the traffic assignment established under mild conditions. The line search procedure used in our algorithm includes the nonmonotone Armijo rule, the non- monotone Goldstein rule and the nonmonotone Wolfe rule as special cases. So, the new algorithm can be viewed as a generalization of the regular convex combination algorithm.展开更多
Improviag transportation system is essential for all people in each city since transport plays a very important role. Using mathematical programming approach transport problem is an effective way to improve transporta...Improviag transportation system is essential for all people in each city since transport plays a very important role. Using mathematical programming approach transport problem is an effective way to improve transportation system. In this paper, the traffic equilibrium problem （TEP） with a general nonadditive route cost function is studied. We formulate the route cost function for each route as a disutility function, which can evaluate route cost function flexibly and analyze the route toll conveniently. Furthermore, we present the TEP with a nonlinear complementary problem （NCP） formulation. The monotonicity and the existence with the NCP formulation are also given under relative assumptions.展开更多
文摘目的探讨第三脑室底造瘘(endoscopic third ventriculostomy,ETV)治疗非交通性脑积水失败的原因和防治方法。方法回顾性分析2例ETV术后造瘘口闭塞的非交通性脑积水病人的临床资料,结合文献复习分析ETV失败的原因,并提出相应的防治方法。结果内镜直视下发现2种不同的瘘口闭塞模式,经2次造瘘和分流术治疗,病人临床症状均明显好转。结论造瘘口和远端脑池的梗阻可能是ETV治疗非交通性脑积水术后失败的重要原因,2次手术时应在内镜直视下探查造瘘口,而保持足够大的造瘘口并合理处理是预防瘘口闭塞的有效手段之一。
文摘In dense wavelength division multiplexing(DWDM) optical transmission systems, cross phase modulation(XPM) due to Kerr effect causes phase shift and intensity modulation in each channel, which will lead the channel capacity to be a random variable. An expression of the channel capacity dealing with XPM effect is presented, and the correctness and accuracy of this method are demonstrated by numerical simulation.
基金supported by the National Basic Research Program of China under Grant No. 2006CB705500the National Natural Science Foundation of China under Grant No. 0631001+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University Volvo Research and Educational Foundations
文摘By handling the travel cost function artfully, the authors formulate the transportation mixed network design problem （MNDP） as a mixed-integer, nonlinear bilevel programming problem, in which the lower-level problem, comparing with that of conventional bilevel DNDP models, is not a side constrained user equilibrium assignment problem, but a standard user equilibrium assignment problem. Then, the bilevel programming model for MNDP is reformulated as a continuous version of bilevel programming problem by the continuation method. By virtue of the optimal-value function, the lower-level assignment problem can be expressed as a nonlinear equality constraint. Therefore, the bilevel programming model for MNDP can be transformed into an equivalent single-level optimization problem. By exploring the inherent nature of the MNDP, the optimal-value function for the lower- level equilibrium assignment problem is proved to be continuously differentiable and its functional value and gradient can be obtained efficiently. Thus, a continuously differentiable but still nonconvex optimization formulation of the MNDP is created, and then a locally convergent algorithm is proposed by applying penalty function method. The inner loop of solving the subproblem is mainly to implement an Ml-or-nothing assignment. Finally, a small-scale transportation network and a large-scale network are presented to verify the proposed model and algorithm.
基金This research is partly supported by National Outstanding Young Investigator Grant(70225005) of National Natural Science Foundation of China and the Project(70471088) of National Natural Science Foundation of China.
文摘This paper presents a unified bination algorithms （such as FrankWolfe problems. Global convergence results are framework of the nonmonotone convex comAlgorithm） for solving the traffic assignment established under mild conditions. The line search procedure used in our algorithm includes the nonmonotone Armijo rule, the non- monotone Goldstein rule and the nonmonotone Wolfe rule as special cases. So, the new algorithm can be viewed as a generalization of the regular convex combination algorithm.
基金supported by the National Natural Science Foundation of China(Grant Nos.71071014,70771005,70631001)the Fundamental Research Funds for Central Universities of China(Grant No. 2009JBM044)
文摘Improviag transportation system is essential for all people in each city since transport plays a very important role. Using mathematical programming approach transport problem is an effective way to improve transportation system. In this paper, the traffic equilibrium problem （TEP） with a general nonadditive route cost function is studied. We formulate the route cost function for each route as a disutility function, which can evaluate route cost function flexibly and analyze the route toll conveniently. Furthermore, we present the TEP with a nonlinear complementary problem （NCP） formulation. The monotonicity and the existence with the NCP formulation are also given under relative assumptions.
