AIM:To study the therapeutic efficacy of a new transnasal ileus tube advanced endoscopically for adhesive small bowel obstruction.METHODS:A total of 186 patients with adhesive small bowel obstruction treated from Sept...AIM:To study the therapeutic efficacy of a new transnasal ileus tube advanced endoscopically for adhesive small bowel obstruction.METHODS:A total of 186 patients with adhesive small bowel obstruction treated from September 2007 to February 2011 were enrolled into this prospective randomized controlled study.The endoscopically advanced new ileus tube was used for gastrointestinal decompression in 96 patients and ordinary nasogastric tube(NGT) was used in 90 patients.The therapeutic efficacy was compared between the two groups.RESULTS:Compared with the NGT group,the ileus tube group experienced significantly shorter time for relief of clinical symptoms and improvement in the findings of abdominal radiograph(4.1 ± 2.3 d vs 8.5 ± 5.0 d) and laboratory tests(P < 0.01).The overall effectiveness rate was up to 89.6% in the ileus tube group and 46.7% in the NGT group(P < 0.01).And 10.4% of the patients in the ileus tube group and 53.3% of the NGT group underwent surgery.For recurrent adhesive bowel obstruction,ileus tube was also significantly more effective than NGT(95.8% vs 31.6%).In the ileus tube group,the drainage output on the first day and the length of hospital stay were significantly different depending on the treatment success or failure(P < 0.05).The abdominal radiographic improvement was correlated with whether or not the patient underwent surgery.CONCLUSION:Ileus tube can be used for adhesive small bowel obstruction.Endoscopic placement of the ileus tube is convenient and worthy to be promoted despite the potential risks.展开更多
In three and six-axis free-bending equipment,the deformation zone length(A)is a fixed mechanical structure parameter modified when the relevant structure is redesigned and manufactured.In this study,a six degree of fr...In three and six-axis free-bending equipment,the deformation zone length(A)is a fixed mechanical structure parameter modified when the relevant structure is redesigned and manufactured.In this study,a six degree of freedom(6-DOF)parallel mechanism was used as the control mechanism of the bending die,and a new method of changing the deformation zone length(A)was proposed.Firstly,an idealized geometric model of free bending-based active motion was established.Then,the influence of the deformation zone length(A)on the bending moment and the bending radius of the tube was analyzed.In addition,the finite element simulation and a kinematic model of free bending-based active motion controlled by the 6-DOF parallel mechanism were established,and bending processes of the SS304 tube with different deformation zone lengths were investigated.Afterwards,the impact of the deformation zone length(A)on the bending radius,bending moment,wall thickness,and motion of the parallel mechanism were analyzed.Finally,experiments were carried out on the free-bending equipment based on the 6-DOF parallel mechanism.Experiments verified the rules in the theoretical analysis,finite element simulation,and kinematic simulation.展开更多
The air precooler of SABRE engine(Synergetic Air-Breathing Rocket Engine)is a tube bundle type of heat exchanger consisting of thousands of small tubes.The cold helium gas flows in the small tube bundle,and the high-s...The air precooler of SABRE engine(Synergetic Air-Breathing Rocket Engine)is a tube bundle type of heat exchanger consisting of thousands of small tubes.The cold helium gas flows in the small tube bundle,and the high-speed hot air circulates outside the tubes and exchanges heat with the helium in the tubes.In this study,the cross-arrangement tube bundle consisting of small tubes with outer diameter of 1mm was taken as the research object.The system simulation calculation and data sorting were carried out.It is found that the empirical correlation of the conventional tube bundle is no longer applicable to the small tube and the reasons for inapplicability are explained by analysis of flow field.In addition,the results show that the average heat transfer coefficient of cross small/micro tube bundle isn’t affected by heat flux,but increases with the increase of Reynolds number,increases with the increase of transverse spacing,and decreases with the increase of longitudinal spacing.The flow resistance coefficient isn’t affected by heat flux and longitudinal spacing,but decreases with the increase of Reynolds number,and decreases with the increase of transverse spacing.展开更多
文摘AIM:To study the therapeutic efficacy of a new transnasal ileus tube advanced endoscopically for adhesive small bowel obstruction.METHODS:A total of 186 patients with adhesive small bowel obstruction treated from September 2007 to February 2011 were enrolled into this prospective randomized controlled study.The endoscopically advanced new ileus tube was used for gastrointestinal decompression in 96 patients and ordinary nasogastric tube(NGT) was used in 90 patients.The therapeutic efficacy was compared between the two groups.RESULTS:Compared with the NGT group,the ileus tube group experienced significantly shorter time for relief of clinical symptoms and improvement in the findings of abdominal radiograph(4.1 ± 2.3 d vs 8.5 ± 5.0 d) and laboratory tests(P < 0.01).The overall effectiveness rate was up to 89.6% in the ileus tube group and 46.7% in the NGT group(P < 0.01).And 10.4% of the patients in the ileus tube group and 53.3% of the NGT group underwent surgery.For recurrent adhesive bowel obstruction,ileus tube was also significantly more effective than NGT(95.8% vs 31.6%).In the ileus tube group,the drainage output on the first day and the length of hospital stay were significantly different depending on the treatment success or failure(P < 0.05).The abdominal radiographic improvement was correlated with whether or not the patient underwent surgery.CONCLUSION:Ileus tube can be used for adhesive small bowel obstruction.Endoscopic placement of the ileus tube is convenient and worthy to be promoted despite the potential risks.
基金supported by the National Natural Science Foundation of China(Nos:U1937206,52175328,52105360)the Opening Project of State Key Lab of Digital Manufacturing Equipment&Technology(No.DMETKF2021004)+3 种基金Jiangsu Province Key Research and Development Project(No.BE2019007-2)Fundamental Research Funds for the Central Universities(No.NS2021046)Ningbo"science and technology innovation 2025"major special project(No.2020Z078)Natural Science Foundation of Jiangsu Province(No.BK20200453).
文摘In three and six-axis free-bending equipment,the deformation zone length(A)is a fixed mechanical structure parameter modified when the relevant structure is redesigned and manufactured.In this study,a six degree of freedom(6-DOF)parallel mechanism was used as the control mechanism of the bending die,and a new method of changing the deformation zone length(A)was proposed.Firstly,an idealized geometric model of free bending-based active motion was established.Then,the influence of the deformation zone length(A)on the bending moment and the bending radius of the tube was analyzed.In addition,the finite element simulation and a kinematic model of free bending-based active motion controlled by the 6-DOF parallel mechanism were established,and bending processes of the SS304 tube with different deformation zone lengths were investigated.Afterwards,the impact of the deformation zone length(A)on the bending radius,bending moment,wall thickness,and motion of the parallel mechanism were analyzed.Finally,experiments were carried out on the free-bending equipment based on the 6-DOF parallel mechanism.Experiments verified the rules in the theoretical analysis,finite element simulation,and kinematic simulation.
基金This work was supported by the National Key Research and Development Program of China(No.2018YFC0310400).
文摘The air precooler of SABRE engine(Synergetic Air-Breathing Rocket Engine)is a tube bundle type of heat exchanger consisting of thousands of small tubes.The cold helium gas flows in the small tube bundle,and the high-speed hot air circulates outside the tubes and exchanges heat with the helium in the tubes.In this study,the cross-arrangement tube bundle consisting of small tubes with outer diameter of 1mm was taken as the research object.The system simulation calculation and data sorting were carried out.It is found that the empirical correlation of the conventional tube bundle is no longer applicable to the small tube and the reasons for inapplicability are explained by analysis of flow field.In addition,the results show that the average heat transfer coefficient of cross small/micro tube bundle isn’t affected by heat flux,but increases with the increase of Reynolds number,increases with the increase of transverse spacing,and decreases with the increase of longitudinal spacing.The flow resistance coefficient isn’t affected by heat flux and longitudinal spacing,but decreases with the increase of Reynolds number,and decreases with the increase of transverse spacing.
