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Objective Based on construction and verification of the lumbar finite element model, the simulation calculation and injury prediction on dynamic response of normal lumbar model and L5 unilateral and bilateral spondylolysis models of the pilot were carried out, so as to explore the influence of persistent flight overload on normal and spondylolysis lumbar vertebrae of the pilot. Methods The precise finite element model of lumbavertebrae was established using reverse engineering software and computer-aided engineering (CAE) technology based on CT images. The validity of the lumbar vertebrae model was verified by static and dynamic in vitro experiments. The biomechanical simulation analysis on normal and spondylolysis lumbar vertebrae of the pilotunder persistent overload was carried out, and the spinal injury was predicted and analyzed by dynamic response index (DRI) injury evaluation and prediction method. Results The maximum isthmus stress of L5 vertebra in unilateral and bilateral spondylolysis models were 105. 29 MPa and 126. 32 MPa, respectively, which were significantly higher than those in normal model. The L4-5 and L5-S1 intervertebral discs of the spondylolysis model were more prone to premature degenerative changes than those of normal model. Combined with DRI spinal injury prediction method, the probability of spinal injury in normal lumbar vertebrae, lumbar vertebrae with L5 unilateral and bilateral spondylolysis were 0. 001 4% , 2. 26% and 3. 21% , respectively, and the probability of spinal injury was significantly increased after the occurrence of spondylolysis. Conclusions The spondylolysis increases the load of lumbar isthmus under flight overload. The results provide more accurate data support for the formulation of training programs and the development of protective devices to ensure flight safety
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Objective To evaluate the effects of the project of ditching for drain on Oncomelania hupensis snail control and flood prevention security and explore the optimal engineering design plan in Dongting Lake region. Methods A retrospective study was performed on the previous studies about the project of ditching for drain. The reference values of project indices were determined. The outside levee of Nanhu New Distinct of Yueyang City in Dongting Lake region was selected as the study area , and the cross section of marshland perpendicular to the center line of the levee was extracted to research. According to the situa?tions of various water levels,a dynamic simulation was performed on the effect and security of the project of ditching for drain through the software FLAC3D. Results The retrospective study showed that the project would be effective when the relatively subsoil water level decreased by 0.35 m,and the soil water content decreased correspondingly. The dynamic simulation by FLAC3D showed that the minimum safe distances between transverse ditch 1,vertical ditch and levee toe should be 25 m and 13 m respectively. The digging depth of transverse ditch and vertical ditch should be 1.2 m and 1.0 m respectively. If the width of marshland in drought period was less than 500 m,one transverse ditch was efficient. Otherwise,more transverse ditches should be set with the intervals of 300 m. Conclusions The project of ditching for drain is an effective ecological snail elimination method. Optimizing the digging depth of ditches and distances between transverse ditches,vertical ditch and levee toe will en?sure the effects and security of the project.
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@#Objective To simulate and evaluate the upper and lower limbs posture on rehabilitation devices training with the Computer Aided Tri-Dimensional Interface Application (CATIA) man-machine analysis module. Methods The human body sizes were determined as the 95th percentile Chinese men. Based on the ergonomics analysis of CATIA, three-dimensional human body was constructed in the upper and lower limbs rehabilitation equipment. Virtual human relationship was established. The attitude of the upper and lower limbs in rehabilitation equipment was simulated and evaluated. Results The human limbs model moved in the normal range and the scores were more than 90 which meant comfortable. The forces of various parts of the body was under the stress limit, as well as the force moment. The arm tension was 3-5 points with the rapid upper limb assessment, which meant the rehabilitation equipment was acceptable. Conclusion Rehabilitation robot may be optimized through the model of the human upper extremity stretch domain analysis, body posture assessment, rapid upper limb assessment and biomechanical analysis under CATIA.
ABSTRACT
Objective To simulate and evaluate the upper and lower limbs posture on rehabilitation devices training with the Computer Aided Tri-Dimensional Interface Application (CATIA) man-machine analysis module. Methods The human body sizes were determined as the 95th percentile Chinese men. Based on the ergonomics analysis of CATIA, three-dimensional human body was constructed in the upper and lower limbs rehabilitation equipment. Virtual human relationship was established. The attitude of the upper and lower limbs in rehabilita-tion equipment was simulated and evaluated. Results The human limbs model moved in the normal range and the scores were more than 90 which meant comfortable. The forces of various parts of the body was under the stress limit, as well as the force moment. The arm tension was 3-5 points with the rapid upper limb assessment, which meant the rehabilitation equipment was acceptable. Conclusion Rehabilitation robot may be optimized through the model of the human upper extremity stretch domain analysis, body posture assessment, rapid upper limb assessment and biomechanical analysis under CATIA.
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Objective: By constructing the cash flow model, it proposed the premium adjustment mechanism of critical illness insurance(CII). Methods: Based on the practical data of critical illness insurance in China, it established some actuarial assumptions and cash flow model to simulate and analyze premium adjustment mechanism of CII. Results: ( 1) Because of the deterioration of critical illness incidence rate and the change of market interest rates , CII guaranteed premium usually resents pricing risk, which showed that the cash flow is negative, sometimes accumulated cash is negative; (2) based on the criteria of insurance cost adjustment, it is suggested that when the loss rate reached more than 70%, which could permit the insurance company adjust the premium, if the loss rate reached more than 80%, it needs to compulsory the insurance companies to adjust premium. Conclusion: The study proposes the mechanism of CII premium adjustment, provides guidance for practice.
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Objective Skin disease is multiple,common disease,and there are so many therapeutic methods.In recent years,physical non-invasive therapy of skin disease has developed rapidly.On the basis of Pennes equation,a series of simulation analysis was completed,and the results confirmed the feasibility and availability as well as the definite safety of curing skin diseases by direct heating.In order to achieve the maximum efficacy and the minimum side effects simultaneously and based on the previous research,exploratory simulation experiment of non-isothermal heating was carried out.Methods The skin temperature fields with non-isothermal heating were simulated by utilizing mathematical tools (Matlab).Results Compared to the previous isothermal heating,during the non-isothermal heating,the temperature of inner skin displayed the rising trend,while it displayed the declining trend during the isothermal heating.Conclusion As compared to isothermal heating,non-isothermal heating has better restraining effect for the bacterium within the inner skin,and less side-effect.
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To improve the braking safety of automobiles, the author studied the effect of differential brake on the stabilities. To analyze the mechanical characteristics of differential brake, automotive subsystem models were built by applying ADAMS/CAR, and automotive mechanics simulation model was built by setting the main subsystems such as body, engine and brake. The simulation model studied the distribution mode of three kinds of differential brake, and beeline braking stability and turning braking stability were simulated. It shows that differential brake can amend turning shortage of automobile brake and improve its braking stability, but the effect of automobile mass on its braking stability is great. So the distribution mode of braking force and the effect of mass change should be considered while differential brake is applied.
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Objective:To simulate the instantaneous distal moving trend of the maxillary first molar based on the three-dimensional finite element mode(l3-FEM)of Forsus distalizing the maxillary first molar with some visco-elastic-plastic characters and explore the favorable loading mode of molar distal movement in Forsus in order to provide biomechanical basis for clinical practice.Methods:A male patient with ClassⅡmalocclusion was selected.The 3-FEM of Forsus distalizing the maxillary first molar was built through spiral CT scanning,Mimics8.0,and Abaqus6.5 software.This study simulated instantaneous distal moving process of the maxillary first molar under three dif-ferent loading modes(loading force was 300 g,point of force was on the center of the crown's buccal surface,loading time was 1s),which included a distalizing force,a distalizing force+counterrotation moment,a distalizing force+countertipping moment+counterrotation moment.Results:When Forsus distalized the maxillary first molar,different loading modes lead to different PDL stress distributions.When the model was added by a distalizing force,the maxillary first molar would be relatively seriously inclined;when added by a distalizing force +counterrotation moment(Mt/F=9),the maxillary first molar would be relatively seriously rotated and when added by a distalizing force+ countertipping momen(tMt/F=9)+counterrotation momen(tMr/F=5),the distal surface of the PDL would bear the lightest stress,and the first molar would achieve approximate translation movement.Conclusion:When mandible is guided forward by Forsus,the maxillary first molar would achieve better molar translation effect if added certain countertipping and counterrotation moment