This study explored the feasibility of employing computer-aided design(CAD)and 3 dimensional(3D)-printed personalized guide plate for the mini-invasive percutaneous internal screw fixation of fractured scaphoid.The st...This study explored the feasibility of employing computer-aided design(CAD)and 3 dimensional(3D)-printed personalized guide plate for the mini-invasive percutaneous internal screw fixation of fractured scaphoid.The study consisted of two parts:(1)experimentation on upper limbs from corpses and(2)preliminary clinical application.Corpse experiments involved upper limbs of 6 adult corpses.The specimens of upper limbs were subjected to plain CT scan.Then the CT data were input into computer to conduct 3D reconstruction of wrist region.The direction and depth of the guide wire and screw were designed on the basis of the principle that screw should lie at the center of scaphoid and the long axis of the screw should be aligned with that of the scaphoid.The carpal bone model and the guide plate were designed and 3D-printed.By using the guide plates,the guide wire was placed and the cannulated compression screw was inserted.The wrist region was examined by X-ray and CT to observe the location of the screw in the scaphoid.The scaphoid was longitudinally excised to grossly observe the location and evaluate the result of screw insertion.For clinical application,the guide plate was employed in 4 patients with fresh scaphoid fracture using the aforementioned operative technique.Our results showed that,in the 6 corpse limbs,the guide plate well fitted the skin surface and the guide wire and screw were accurately put in place in one session.X-ray examination and gross observation confirmed that the screw was satisfactorily positioned and the result met the requirements of the preoperative design.For 4 patients,the guide wire and screw were all precisely inserted into place in one session.The operation time and X-ray exposure times were apparently reduced.The imaging examination exhibited satisfactory results and the hand functioned well.It was concluded that the operative guide plate used for the miniinvasive percutaneous internal screw fixation of fractured scaphoid not only can assist in accurate placement of screw but also 展开更多
Due to the pressure gain combustion characteristics,the rotating detonation combustor(RDC)can enhance thermodynamic cycle efficiency.Therefore,the performance of gas-turbine engine can be further improved with this co...Due to the pressure gain combustion characteristics,the rotating detonation combustor(RDC)can enhance thermodynamic cycle efficiency.Therefore,the performance of gas-turbine engine can be further improved with this combustion technology.In the present study,the RDC operation performance with a turbine guide vane(TGV)is experimentally investigated.Hydrogen and air are used as propellants while hydrogen and air mass flow rate are about 16.1 g/s and 500 g/s and the equivalence ratio is about 1.0.A pre-detonator is used to ignite the mixture.High-frequency dynamic pressure transducers and silicon pressure sensors are employed to measure pressure oscillations and static pressure in the combustion chamber.The experimental results show that the steady propagation of rotating detonation wave(RDW)is observed in the combustion chamber and the mean propagation velocity is above 1650 m/s,reaching over 84%of theoretical Chapman-Jouguet detonation velocity.Clockwise and counterclockwise propagation directions of RDW are obtained.For clockwise propagation direction,the static pressure is about 15%higher in the combustor compared with counterclockwise propagation direction,but the RDW dominant frequency is lower.When the oblique shock wave propagates across the TGV,the pressure oscillations reduces significantly.In addition,as the detonation products flow through the TGV,the static pressure drops up to 32%and 43%for clockwise and counterclockwise propagation process respectively.展开更多
A new instrument for checking the quality of elevator guide rails is introduced.With this instrument,the general geometric errors such as straightness,flatness,squareness,twist,thickness and height can be measured aut...A new instrument for checking the quality of elevator guide rails is introduced.With this instrument,the general geometric errors such as straightness,flatness,squareness,twist,thickness and height can be measured automatically,simultaneously in a short time with high accuracy.It is very useful for elevator guide rail factories to improve their work efficiency and the quality of their products.展开更多
文摘This study explored the feasibility of employing computer-aided design(CAD)and 3 dimensional(3D)-printed personalized guide plate for the mini-invasive percutaneous internal screw fixation of fractured scaphoid.The study consisted of two parts:(1)experimentation on upper limbs from corpses and(2)preliminary clinical application.Corpse experiments involved upper limbs of 6 adult corpses.The specimens of upper limbs were subjected to plain CT scan.Then the CT data were input into computer to conduct 3D reconstruction of wrist region.The direction and depth of the guide wire and screw were designed on the basis of the principle that screw should lie at the center of scaphoid and the long axis of the screw should be aligned with that of the scaphoid.The carpal bone model and the guide plate were designed and 3D-printed.By using the guide plates,the guide wire was placed and the cannulated compression screw was inserted.The wrist region was examined by X-ray and CT to observe the location of the screw in the scaphoid.The scaphoid was longitudinally excised to grossly observe the location and evaluate the result of screw insertion.For clinical application,the guide plate was employed in 4 patients with fresh scaphoid fracture using the aforementioned operative technique.Our results showed that,in the 6 corpse limbs,the guide plate well fitted the skin surface and the guide wire and screw were accurately put in place in one session.X-ray examination and gross observation confirmed that the screw was satisfactorily positioned and the result met the requirements of the preoperative design.For 4 patients,the guide wire and screw were all precisely inserted into place in one session.The operation time and X-ray exposure times were apparently reduced.The imaging examination exhibited satisfactory results and the hand functioned well.It was concluded that the operative guide plate used for the miniinvasive percutaneous internal screw fixation of fractured scaphoid not only can assist in accurate placement of screw but also
基金the National Natural Science Foundation of China(No.11702143 and 11802137)the Fundamental Research Funds for the Central Universities(No.30918011343 and 30919011259).
文摘Due to the pressure gain combustion characteristics,the rotating detonation combustor(RDC)can enhance thermodynamic cycle efficiency.Therefore,the performance of gas-turbine engine can be further improved with this combustion technology.In the present study,the RDC operation performance with a turbine guide vane(TGV)is experimentally investigated.Hydrogen and air are used as propellants while hydrogen and air mass flow rate are about 16.1 g/s and 500 g/s and the equivalence ratio is about 1.0.A pre-detonator is used to ignite the mixture.High-frequency dynamic pressure transducers and silicon pressure sensors are employed to measure pressure oscillations and static pressure in the combustion chamber.The experimental results show that the steady propagation of rotating detonation wave(RDW)is observed in the combustion chamber and the mean propagation velocity is above 1650 m/s,reaching over 84%of theoretical Chapman-Jouguet detonation velocity.Clockwise and counterclockwise propagation directions of RDW are obtained.For clockwise propagation direction,the static pressure is about 15%higher in the combustor compared with counterclockwise propagation direction,but the RDW dominant frequency is lower.When the oblique shock wave propagates across the TGV,the pressure oscillations reduces significantly.In addition,as the detonation products flow through the TGV,the static pressure drops up to 32%and 43%for clockwise and counterclockwise propagation process respectively.
文摘A new instrument for checking the quality of elevator guide rails is introduced.With this instrument,the general geometric errors such as straightness,flatness,squareness,twist,thickness and height can be measured automatically,simultaneously in a short time with high accuracy.It is very useful for elevator guide rail factories to improve their work efficiency and the quality of their products.
