As commercial drone delivery becomes increasingly popular,the extension of the vehicle routing problem with drones(VRPD)is emerging as an optimization problem of inter-ests.This paper studies a variant of VRPD in mult...As commercial drone delivery becomes increasingly popular,the extension of the vehicle routing problem with drones(VRPD)is emerging as an optimization problem of inter-ests.This paper studies a variant of VRPD in multi-trip and multi-drop(VRP-mmD).The problem aims at making schedules for the trucks and drones such that the total travel time is minimized.This paper formulate the problem with a mixed integer program-ming model and propose a two-phase algorithm,i.e.,a parallel route construction heuristic(PRCH)for the first phase and an adaptive neighbor searching heuristic(ANSH)for the second phase.The PRCH generates an initial solution by con-currently assigning as many nodes as possible to the truck–drone pair to progressively reduce the waiting time at the rendezvous node in the first phase.Then the ANSH improves the initial solution by adaptively exploring the neighborhoods in the second phase.Numerical tests on some benchmark data are conducted to verify the performance of the algorithm.The results show that the proposed algorithm can found better solu-tions than some state-of-the-art methods for all instances.More-over,an extensive analysis highlights the stability of the pro-posed algorithm.展开更多
Objective To evaluate the effect of propofol,sevoflurane,and dexmedetomidine on respiratory complications inchildren undergoing fiberoptic bronchoscopy(FOB).Methods This double-blind randomized clinical trial was cond...Objective To evaluate the effect of propofol,sevoflurane,and dexmedetomidine on respiratory complications inchildren undergoing fiberoptic bronchoscopy(FOB).Methods This double-blind randomized clinical trial was conductedamong 120 children aged 1 month to 3 years undergoing FOB.The patients were randomized into 3 groups(n=40)foranesthesia induction with sevoflurane inhalation,1 mg/kg propofol,or 1μg/kg dexmedetomidine before bronchoscopy,andthe changes in hemodynamic parameters,sedation level,and respiratory complications during and after the procedure wereassessed.Results The patients'heart rate during bronchoscopy was significantly lower and the mean arterial blood pressuresignificantly higher in dexmedetomidine group than in sevoflurane and propofol groups(P<0.05).Cough duringbronchoscopy did not occur in any of the cases in propofol group,while the highest frequency of cough was recorded indexmedetomidine group.The incidence of laryngospasm in the propofol group(12.5%)was significantly lower than those insevoflurane and dexmedetomidine groups(30%and 32.5%,respectively)(P<0.05).Conclusion Sevoflurane and propofol aresafe and suitable for anesthesia induction in children below 3 years of age undergoing diagnostic FOB and can achieve bettersedative effect and lower the incidences of cough and respiratory complications as compared with dexmedetomidine.展开更多
Objective To observe the ultrasonic manifestations and age distribution of internal abdominal hernia in children.Methods Data of 53 children with internal abdominal hernia confirmed by operation were retrospectively a...Objective To observe the ultrasonic manifestations and age distribution of internal abdominal hernia in children.Methods Data of 53 children with internal abdominal hernia confirmed by operation were retrospectively analyzed.The ultrasonic findings were observed,and the age distribution of children was analyzed.Results Among 53 cases,"cross sign"was observed in 22 cases(22/53,41.51%),and"hernia ring beak sign"was detected in 26 cases(26/53,49.06%)by preoperative ultrasound,according to which 21 cases were diagnosed as internal abdominal hernia,with the accuracy of 39.62%(21/53).Meanwhile,manifestations of intestinal obstruction were noticed in 48 cases(48/53,90.57%),and intestinal necrosis was considered in 22 cases(22/53,41.51%).Four cases were misdiagnosed as intestinal perforation,appendicitis,intestinal atresia and volvulus,each in 1 case.The onset age of postoperative adhesive band internal hernia was larger than that of mesenteric hiatal hernia(P<0.05),while no significant difference of onset age was found among other types of internal abdominal hernias(all P>0.05).Intestinal ischemic necrosis was found in 25 cases,while the incidence of intestinal necrosis in children aged≤1 year,>1 and≤3 years,>3 and≤7 years and those>7 years was 66.67%(12/18),33.33%(4/12),36.36%(4/11)and 41.67%(5/12),respectively.Conclusion The characteristic ultrasonic findings of internal abdominal hernia in children included"cross sign"and"hernia ring beak sign".Internal abdominal hernia in children under 1 year had high risk of intestinal necrosis.展开更多
Large calculation error can be formed by directly employing the conventional Yee’s grid to curve surfaces.In order to alleviate such condition,unconditionally stable CrankNicolson Douglas-Gunn(CNDG)algorithm with is ...Large calculation error can be formed by directly employing the conventional Yee’s grid to curve surfaces.In order to alleviate such condition,unconditionally stable CrankNicolson Douglas-Gunn(CNDG)algorithm with is proposed for rotationally symmetric multi-scale problems in anisotropic magnetized plasma.Within the CNDG algorithm,an alternative scheme for the simulation of anisotropic plasma is proposed in body-of-revolution domains.Convolutional perfectly matched layer(CPML)formulation is proposed to efficiently solve the open region problems.Numerical example is carried out for the illustration of effectiveness including the efficiency,resources,and absorption.Through the results,it can be concluded that the proposed scheme shows considerable performance during the simulation.展开更多
文摘As commercial drone delivery becomes increasingly popular,the extension of the vehicle routing problem with drones(VRPD)is emerging as an optimization problem of inter-ests.This paper studies a variant of VRPD in multi-trip and multi-drop(VRP-mmD).The problem aims at making schedules for the trucks and drones such that the total travel time is minimized.This paper formulate the problem with a mixed integer program-ming model and propose a two-phase algorithm,i.e.,a parallel route construction heuristic(PRCH)for the first phase and an adaptive neighbor searching heuristic(ANSH)for the second phase.The PRCH generates an initial solution by con-currently assigning as many nodes as possible to the truck–drone pair to progressively reduce the waiting time at the rendezvous node in the first phase.Then the ANSH improves the initial solution by adaptively exploring the neighborhoods in the second phase.Numerical tests on some benchmark data are conducted to verify the performance of the algorithm.The results show that the proposed algorithm can found better solu-tions than some state-of-the-art methods for all instances.More-over,an extensive analysis highlights the stability of the pro-posed algorithm.
文摘Objective To evaluate the effect of propofol,sevoflurane,and dexmedetomidine on respiratory complications inchildren undergoing fiberoptic bronchoscopy(FOB).Methods This double-blind randomized clinical trial was conductedamong 120 children aged 1 month to 3 years undergoing FOB.The patients were randomized into 3 groups(n=40)foranesthesia induction with sevoflurane inhalation,1 mg/kg propofol,or 1μg/kg dexmedetomidine before bronchoscopy,andthe changes in hemodynamic parameters,sedation level,and respiratory complications during and after the procedure wereassessed.Results The patients'heart rate during bronchoscopy was significantly lower and the mean arterial blood pressuresignificantly higher in dexmedetomidine group than in sevoflurane and propofol groups(P<0.05).Cough duringbronchoscopy did not occur in any of the cases in propofol group,while the highest frequency of cough was recorded indexmedetomidine group.The incidence of laryngospasm in the propofol group(12.5%)was significantly lower than those insevoflurane and dexmedetomidine groups(30%and 32.5%,respectively)(P<0.05).Conclusion Sevoflurane and propofol aresafe and suitable for anesthesia induction in children below 3 years of age undergoing diagnostic FOB and can achieve bettersedative effect and lower the incidences of cough and respiratory complications as compared with dexmedetomidine.
文摘Objective To observe the ultrasonic manifestations and age distribution of internal abdominal hernia in children.Methods Data of 53 children with internal abdominal hernia confirmed by operation were retrospectively analyzed.The ultrasonic findings were observed,and the age distribution of children was analyzed.Results Among 53 cases,"cross sign"was observed in 22 cases(22/53,41.51%),and"hernia ring beak sign"was detected in 26 cases(26/53,49.06%)by preoperative ultrasound,according to which 21 cases were diagnosed as internal abdominal hernia,with the accuracy of 39.62%(21/53).Meanwhile,manifestations of intestinal obstruction were noticed in 48 cases(48/53,90.57%),and intestinal necrosis was considered in 22 cases(22/53,41.51%).Four cases were misdiagnosed as intestinal perforation,appendicitis,intestinal atresia and volvulus,each in 1 case.The onset age of postoperative adhesive band internal hernia was larger than that of mesenteric hiatal hernia(P<0.05),while no significant difference of onset age was found among other types of internal abdominal hernias(all P>0.05).Intestinal ischemic necrosis was found in 25 cases,while the incidence of intestinal necrosis in children aged≤1 year,>1 and≤3 years,>3 and≤7 years and those>7 years was 66.67%(12/18),33.33%(4/12),36.36%(4/11)and 41.67%(5/12),respectively.Conclusion The characteristic ultrasonic findings of internal abdominal hernia in children included"cross sign"and"hernia ring beak sign".Internal abdominal hernia in children under 1 year had high risk of intestinal necrosis.
文摘Large calculation error can be formed by directly employing the conventional Yee’s grid to curve surfaces.In order to alleviate such condition,unconditionally stable CrankNicolson Douglas-Gunn(CNDG)algorithm with is proposed for rotationally symmetric multi-scale problems in anisotropic magnetized plasma.Within the CNDG algorithm,an alternative scheme for the simulation of anisotropic plasma is proposed in body-of-revolution domains.Convolutional perfectly matched layer(CPML)formulation is proposed to efficiently solve the open region problems.Numerical example is carried out for the illustration of effectiveness including the efficiency,resources,and absorption.Through the results,it can be concluded that the proposed scheme shows considerable performance during the simulation.
