Objective:Interpersonal brain synchronization(IBS)has emerged as a significant concept in understanding collaborative team dynamics,with functional near-infrared spectroscopy(fNIRS)proving to be a vital tool in its as...Objective:Interpersonal brain synchronization(IBS)has emerged as a significant concept in understanding collaborative team dynamics,with functional near-infrared spectroscopy(fNIRS)proving to be a vital tool in its assessment.This review aims to collate and analyze the literature on the application of fNIRS in various team settings,emphasizing its potential utility in surgical environments.Methods:A thorough search and screening process across multiple databases resulted in 17 studies being reviewed,with a focus on the utilization of fNIRS to measure IBS in different collaborative tasks.This review examined the tasks employed,participant demographics,organizational structures of teams,methodologies for IBS measurement,and correlations between brain synchronization and behavioral measurements.Results:fNIRS emerged as a non-invasive,cost-effective,and portable tool,predominantly used to assess IBS in pair-based tasks with a variety of participant demographics.Wavelet transform coherence was the primary method used for measuring synchronization,particularly in the prefrontal brain region.A consistent correlation was found between increased brain synchronization and enhanced team performance,underscoring the potential of fNIRS in understanding and optimizing team dynamics.Conclusion:This review establishes fNIRS as a promising tool for investigating the neural mechanisms underlying team cooperation,providing invaluable insights for potential applications in surgical settings.While acknowledging the limitations in the current literature,the review highlights the need for further research with larger sample sizes and varied task complexities to solidify the understanding of IBS and its impact on team performance.The ultimate goal is to leverage fNIRS in assessing and improving surgical team dynamics,contributing to improved patient outcomes and safety.展开更多
In this work, three-dimensional molecular dynamics simulation is carried out to elucidate the nanoindentation behaviour of single crystal Ni. The substrate indenter system is modelled using hybrid interatomic potentia...In this work, three-dimensional molecular dynamics simulation is carried out to elucidate the nanoindentation behaviour of single crystal Ni. The substrate indenter system is modelled using hybrid interatomic potentials including the manybody potential （embedded atom method） and two-body Morse potential. The spherical indenter is chosen, and the simulation is performed for different loading rates from 10 m/s to 200 m/s. Results show that the maximum indentation load and hardness of the system increase with the increase of velocity. The effect of indenter size on the nanoindentation response is also analysed. It is found that the maximum indentation load is higher for the large indenter whereas the hardness is higher for the smaller indenter. Dynamic nanoindentation is carried out to investigate the behaviour of Ni substrate to multiple loading-unloading cycles. It is observed from the results that the increase in the number of loading unloading cycles reduces the maximum load and hardness of the Ni substrate. This is attributed to the decrease in recovery force due to defects and dislocations produced after each indentation cycle.展开更多
Aiming at the missile avoidance problem of the unmanned aerial vehicle(UAV)in complex obstacle environments,this work proposes a collision-avoidance method based on receding horizon optimization.The proposed method ge...Aiming at the missile avoidance problem of the unmanned aerial vehicle(UAV)in complex obstacle environments,this work proposes a collision-avoidance method based on receding horizon optimization.The proposed method generated a specific trajectory for the UAV to effectively induce the proportional navigation missile to successfully intercept the obstacle,thereby accomplishing the evasive maneuver.The evasive maneuver was divided into two distinct stages,namely the collision-inducing phase and the fast departure phase.The obstacle potential field-based target selection algorithm was employed to identify the most appropriate target obstacle,while the induced trajectory was determined through a combination of receding horizon optimization and the hp-adaptive pseudo-spectral method.Simulation experiments were carried out under three different types of obstacle environments and one multiobstacle environment,and the simulation results show that the method proposed in this paper greatly improves the success rate of UAV evasive maneuvers,proving the effectiveness of this method.展开更多
Objective While there is consensus regarding a positive effect of video gaming on dexterity,little is known regarding how much traditional laparoscopic practice can or should be substituted with video gaming.This stud...Objective While there is consensus regarding a positive effect of video gaming on dexterity,little is known regarding how much traditional laparoscopic practice can or should be substituted with video gaming.This study was designed to assess the effects of varying the amount of traditional practice in a lap box trainer and video gaming on performance in two fundamentals of laparoscopic surgery core tasks.Methods Undergraduate and medical students were recruited and randomized into one of four groups:a control group,a lap box group,a video game group,and a combined group with 50%of the time allocated to each modality.Performance in the peg transfer and precision cutting tasks was assessed both prior to and following the 6 training sessions.Results Peg transfer performance significantly improved in the lap box group(168.4±70.6 s vs.332.9±178.2 s,p<0.001),video game group(176.7±53.3 s vs.300.0±101.2 s,p<0.001)and combined group(214.2±86.9 s vs.406.8±239.5 s,p=0.002)after training.Similar improvements were also observed in precision cutting performance in the lap box group(413.1±138.4 s vs.614.3±211.4 s,p=0.002),video game group(434.1±150.8 s vs.609.2±233.2 s,p=0.007)and combined group(469.2±185.3 s vs.663.8±296.3 s,p=0.020).When analyzing improvements in performance across three different training groups compared with the control group,we found that both the lap box group(p<0.001)and the combined group(p<0.001)showed better improvement in both tasks,and the video game group had significantly better outcomes in the precision cutting task(p=0.003).Conclusion Traditional lap box training remains the most effective method for improving the performance of simulated laparoscopic surgery.Video games can be encouraged to enhance skills retention and supplement simulated practice outside of a formal training curriculum.展开更多
A Mg-Gd-Y-Zn-Zr magnesium alloy with different initial states was extruded under different extrusion parameters.The effect of solution treatment and extrusion parameters on the microstructure,texture and mechanical pr...A Mg-Gd-Y-Zn-Zr magnesium alloy with different initial states was extruded under different extrusion parameters.The effect of solution treatment and extrusion parameters on the microstructure,texture and mechanical properties were analyzed in detail,and the abnormal texture formation and strengthening mechanism was revealed.When extruded at low temperature and small extrusion ratio,the bimodal microstructure consisting of fine dynamically recrystallized grains and coarse deformed grains occurred both in the as-cast alloy and solution-treated alloy.When the extrusion temperature and extrusion ratio were increased,the amount and size of dynamically recrystallized grains increased and the grain size of the solution-treated alloy showed higher growth rate.Furthermore,an abnormal texture with<0001>parallel with extrusion direction developed due to the occurrence of non-basal slip and continuous dynamic recrystallization.This could be enhanced by solution treatment,high temperature,and large extrusion ratio.Both the as-cast alloy and solution-treated alloy exhibited the highest tensile strength after extrusion at 300℃with an extrusion ratio of 9.Grain refinement was the main strengthening mechanism utilized in both the as-cast alloy and the solution-treated alloy.Work hardening played an important role in the sample extruded at low temperature and small extrusion ratio,with the highest contribution of about 33 MPa after extrusion at 300℃with an extrusion ratio of 9.Texture strengthening contributed more in the sample extruded at high temperature and large extrusion ratio,but no more than 24.1 MPa.Solution strengthening was another strengthening mechanism in the extruded as-cast alloy,especially at high temperature and large extrusion ratio(no more than 9 MPa).展开更多
In the current study, streak camera was used to find concentricity of the assembly during detonation,investigate and compare shock front within the high explosive and behavior of the shock front on the surface of the ...In the current study, streak camera was used to find concentricity of the assembly during detonation,investigate and compare shock front within the high explosive and behavior of the shock front on the surface of the liner, one containing wave shaper and the other without wave shaper. Streaks revealed that the whole assembly was concentric till the formation of the jet. Observed streaks vindicate the uniform propagation of shock front in both the cases. Results obtained for shock front velocities are in agreement with those obtained from simulations. In the presence of wave shaper higher shock front velocity was observed both in simulation and experiment. Simulation without wave-shaper showed that shock front struck the copper cone at grazing angle while in the presence of wave-shaper it struck at an angle of 125.展开更多
Syndrome differentiation is the core diagnosis method of Traditional Chinese Medicine(TCM).We propose a method that simulates syndrome differentiation through deductive reasoning on a knowledge graph to achieve automa...Syndrome differentiation is the core diagnosis method of Traditional Chinese Medicine(TCM).We propose a method that simulates syndrome differentiation through deductive reasoning on a knowledge graph to achieve automated diagnosis in TCM.We analyze the reasoning path patterns from symptom to syndromes on the knowledge graph.There are two kinds of path patterns in the knowledge graph:one-hop and two-hop.The one-hop path pattern maps the symptom to syndromes immediately.The two-hop path pattern maps the symptom to syndromes through the nature of disease,etiology,and pathomechanism to support the diagnostic reasoning.Considering the different support strengths for the knowledge paths in reasoning,we design a dynamic weight mechanism.We utilize Naïve Bayes and TF-IDF to implement the reasoning method and the weighted score calculation.The proposed method reasons the syndrome results by calculating the possibility according to the weighted score of the path in the knowledge graph based on the reasoning path patterns.We evaluate the method with clinical records and clinical practice in hospitals.The preliminary results suggest that the method achieves high performance and can help TCM doctors make better diagnosis decisions in practice.Meanwhile,the method is robust and explainable under the guide of the knowledge graph.It could help TCM physicians,especially primary physicians in rural areas,and provide clinical decision support in clinical practice.展开更多
In this paper,the node based smoothed-strain Abaqus user element(UEL)in the framework of finite element method is introduced.The basic idea behind of the node based smoothed finite element(NSFEM)is that finite element...In this paper,the node based smoothed-strain Abaqus user element(UEL)in the framework of finite element method is introduced.The basic idea behind of the node based smoothed finite element(NSFEM)is that finite element cells are divided into subcells and subcells construct the smoothing domain associated with each node of a finite element cell[Liu,Dai and Nguyen-Thoi(2007)].Therefore,the numerical integration is globally performed over smoothing domains.It is demonstrated that the proposed UEL retains all the advantages of the NSFEM,i.e.,upper bound solution,overly soft stiffness and free from locking in compressible and nearly-incompressible media.In this work,the constant strain triangular(CST)elements are used to construct node based smoothing domains,since any complex two dimensional domains can be discretized using CST elements.This additional challenge is successfully addressed in this paper.The efficacy and robustness of the proposed work is obtained by several benchmark problems in both linear and nonlinear elasticity.The developed UEL and the associated files can be downloaded from https://github.com/nsundar/NSFEM.展开更多
This work aims to understand the inefficiency of nanoprecipitates to strengthen a weakly textured,polycrystalline Mg-Gd-Y-Zr alloy.An experimental micromechanical approach consisting on micropillar compression combine...This work aims to understand the inefficiency of nanoprecipitates to strengthen a weakly textured,polycrystalline Mg-Gd-Y-Zr alloy.An experimental micromechanical approach consisting on micropillar compression combined with analytical electron microscopy is put in place to analyze the effect of nanoprecipitation on soft and hard basal slip and twinning in individual grains with different orientations.This study shows that,in grains that are favorably oriented for basal slip(“soft”basal slip),aging leads to extreme localization due to the ability of basal dislocations to shear the nanoparticles,resulting overall in the softening of basal systems.Additionally,in grains in which the c-axis is almost perpendicular to the compression axis,prismatic slip dominates deformation in the solid solution state and nanoprecipitation favors twinning due to the concomitant lattice solute depletion.Finally,in grains oriented with their c-axis making an angle of about 5-7°with respect to the compression axis,which deform mainly by“hard”basal slip,precipitation leads to the strengthening of basal systems in the absence of obvious localization.This work reveals that the poor hardening response of the polycrystalline alloy is related to the capability of basal dislocations to shear the nanoparticles,in the absence of Orowan looping events,and to the associated basal slip localization.展开更多
In light of the problem of radiolysis of the solvent system in PUREX(plutonium uranium recovery by extraction) process, γ and α irradiation stabilities of tributylphosphate(TBP)/n-dodecane/nitric acid system were st...In light of the problem of radiolysis of the solvent system in PUREX(plutonium uranium recovery by extraction) process, γ and α irradiation stabilities of tributylphosphate(TBP)/n-dodecane/nitric acid system were studied using60 Co γ-rays and α particles from238 Pu. The main degradation products, dibutyl phosphate(HDBP)and monobutyl phosphate(H2MBP) were detected by the gas chromatography-mass spectrometry(GC-MS),and the degradation products that could not be easily removed by the washing procedure were measured by the Pu retention. Effects of the absorbed dose, the HNO3 concentration, and the cumulative dose on the irradiation stability of the systems were investigated. The yields of HDBP, H2 MBP and the Pu retention increased with the absorbed dose. The HNO3 concentration affected significantly on the yield of HDBP, but had little impact on the output of H2 MBP and Pu retention. For a similar absorbed dose, the Pu retention of the solvent by alpha irradiation is larger than that by gamma irradiation.展开更多
In the present work, three-dimensional molecular dynamics simulation is carried out to elucidate the nanoinden- tation behaviors of CuZr Bulk metallic glasses （BMGs）. The substrate indenter system is modeled using h...In the present work, three-dimensional molecular dynamics simulation is carried out to elucidate the nanoinden- tation behaviors of CuZr Bulk metallic glasses （BMGs）. The substrate indenter system is modeled using hybrid interatomic potentials including both many-body Finnis Sinclair （FS） and two-body Morse potentials. A spherical rigid indenter （diameter= 60 A（1 A = 10 ^-10 m）） is employed to simulate the indentation process. Three samples of BMGs including Cu25Zr75, CusoZr50, and Cu75Zr25 are designed and the metallic glasses are formed by rapid cooling from the melt state at about 2000 K. The radial distribution functions are analyzed to reveal the dynamical evolution of the structure of the atoms with different compositions and different cooling rates. The mechanical behavior can be well understood in terms of load-depth curves and Hardness-depth curves during the nanoindentation process. Our results indicate a positive linear relationship between the hardness and the Cu concentration of the BMG sample. To reveal the importance of cooling rate provided during the processing of BMGs, we investigate the indentation behaviors of CusoZr50 at three different quenching rates. Nanoindentation results and radial distribution function （RDF） curves at room temperature indicate that a sample can be made harder and more stable by slowing down the quenching rate.展开更多
Objective:Surgeons are required to wear heavy personal protective equipment while delivering care to patients during the COVID-19 pandemic.We examined the impact of wearing double gloves on surgeons’performance in la...Objective:Surgeons are required to wear heavy personal protective equipment while delivering care to patients during the COVID-19 pandemic.We examined the impact of wearing double gloves on surgeons’performance in laparoscopic surgery.Methods:Eleven surgeons-in-training at the Surgical Simulation Research Lab of the University of Alberta were recruited to perform laparoscopic cutting tasks in simulation while wearing none,one pair,and two pairs of surgical gloves.Forces applied to laparoscopic instruments were measured.Results:Wearing gloves prolonged task times(one pair of gloves:301.6±61.7 s;two pairs of gloves:295.8±65.3 s)compared with no gloves(241.7±46.9 s;p=0.043).Wearing double gloves increased cutting errors(20.4±5.1 mm^(2))compared with wearing one pair of gloves(16.9±5.5 mm^(2))and no gloves(14.4±4.6 mm^(2);p=0.030).Wearing gloves reduced the peak force(one pair of gloves:2.4±0.7 N;two pairs of gloves:2.7±0.6 N;no gloves:3.4±1.4 N;p=0.049),and the total force(one pair of gloves:10.1±2.8 N;two pairs of gloves:10.3±2.6 N;no glove:12.6±1.9 N;p=0.048)delivered onto lapa-roscopic scissors compared with wearing no glove.Conclusion:The combined effects of wearing heavy gloves and using tools reduced the touching sensation,which limited the surgeons’confidence in performing surgical tasks.Increasing practice in simulation is suggested to allow surgeons to overcome difficulties brought by personal protective equipment.展开更多
We employ ab-initio calculations to analyze the mechanical, electronic, optical and also thermoelectric properties associated with AGeO3（A = Ca, Sr） compounds. The full-potential linearized augmented plane wave（FP-...We employ ab-initio calculations to analyze the mechanical, electronic, optical and also thermoelectric properties associated with AGeO3（A = Ca, Sr） compounds. The full-potential linearized augmented plane wave（FP-LAPW） technique in the generalized gradient approximation（GGA-PBEsol） and the lately designed Tran-Blaha-modified Becke-Johnson exchange potential are utilized to examine the mechanical and optoelectronic properties respectively. To explore the thermoelectric quality, we use the semi-classical Boltzmann transport theory. The particular structural stabilities regarding AGeO3（A = Ca, Sr） materials are validated simply by computations from the elastic constants. The energy band structural framework and the density of states are displayed to indicate indirect bandgap under ambient conditions. The particular computed optical attributes that reveal prospective optoelectronic applications are usually elucidated simply by studying ε1（0） and also Eg, which can be connected by means of Penn＇s design. The optical details uncover the actual suitability to power ranging products. Finally, the Boltz Tra P code is executed to analyze the actual thermoelectric properties, which usually presents that the increase of internal temperatures can enhance the electric conductivity, thermal conductivity and also the power factor, whilst Seebeck coefficient decreases. Therefore, the studied materials will also be ideal for thermoelectric products to understand helpful option for alternative energy resources.展开更多
Aim:To examine the significance of team collaboration in the context of complex laparoscopic surgery,laparoscopic tasks performed by single operators are compared against that of dyad teams.Methods:The laparoscopic ta...Aim:To examine the significance of team collaboration in the context of complex laparoscopic surgery,laparoscopic tasks performed by single operators are compared against that of dyad teams.Methods:The laparoscopic tasks require subjects to reach,grasp and transport a ring through a rollercoaster obstacle using a pair of laparoscopic graspers.The task was performed either bimanually(using both hands)or unimanually(using their preferred hands)in a dyad team.Results:Twelve participants completed all the tasks.The dyad teams recorded significantly greater number of anticipatory movements than individuals who performed the task bimanually(p<0.05).However,there is no significant difference in the task completion time(p=0.701)and the number of errors(p=0.860)recorded between the dyad and the bimanual group.Conclusion:Compared to a single operator,dyad operators performed the task with greater number of anticipatory movements.The increased movement synchronization can help benefit surgical education and team training.展开更多
The versatile,and tunable surface chemistry of two-dimensional(2D)MXenes coupled with their distinct properties including hydrophilic nature,favorable ion transport and metallic conductivity make them an ideal candida...The versatile,and tunable surface chemistry of two-dimensional(2D)MXenes coupled with their distinct properties including hydrophilic nature,favorable ion transport and metallic conductivity make them an ideal candidate for energy storage devices.Modifying surface terminations by doping heteroatom is an efficient approach to improve layer spacing and electrochemical active sites of the MXenes.However,nitrogen doping in 2D materials has been an effective way to enhance their electrochemical characteristics.In this study,N-Nb2CTx MXene was synthesized by utilizing the hydrothermal method in which nitrogen doping in MXene was confirmed through several characterization techniques.Tuning of MXene surface by a cost-effective strategy has shown improved performance for energy storage.After doping nitrogen in Nb2CTx MXene,it has shown enhanced pseudocapacitance performance in 1 M potassium hydroxide(KOH),elevating the electrochemical properties.N-Nb2CTx MXene has displayed a better specific capacitance of up to 640 F·g-1 while pristine Nb2CTx MXene has shown 276 F·g-1 from the cyclic voltammogram(CV)at a scan rate of 5 mV·s-1.In addition,an asymmetric device of activated carbon/N-Nb2CTx was assembled for real-world applications,it has exhibited refined results.The asymmetric device has shown remarkable cyclic stability of 90%capacity retention at a current density of 5 A·g-1 for 5000 cycles.Additionally,the detailed density functional theory(DFT)calculations support the stability of nitrogen replacing the fluorine functional group,complementing the experiment.展开更多
In the recent years, the phase field method for simulating fracture problems has received considerable attention. This is due to the salient features of the method: 1) it can be incorporated into any conventional fini...In the recent years, the phase field method for simulating fracture problems has received considerable attention. This is due to the salient features of the method: 1) it can be incorporated into any conventional finite element software;2) has a scalar damage variable is used to represent the discontinuous surface implicitly and 3) the crack initiation and subsequent propagation and branching are treated with less complexity. Within this framework, the linear momentum equations are coupled with the diffusion type equation, which describes the evolution of the damage variable. The coupled nonlinear system of partial differential equations are solved in a 'staggered? approach. The present work discusses the implementation of the phase field method for brittle fracture within the open-source finite element software, FEniCS. The FEniCS provides a framework for the automated solutions of the partial differential equations. The details of the implementation which forms the core of the analysis are presented. The implementation is validated by solving a few benchmark problems and comparing the results with the open literature.展开更多
文摘Objective:Interpersonal brain synchronization(IBS)has emerged as a significant concept in understanding collaborative team dynamics,with functional near-infrared spectroscopy(fNIRS)proving to be a vital tool in its assessment.This review aims to collate and analyze the literature on the application of fNIRS in various team settings,emphasizing its potential utility in surgical environments.Methods:A thorough search and screening process across multiple databases resulted in 17 studies being reviewed,with a focus on the utilization of fNIRS to measure IBS in different collaborative tasks.This review examined the tasks employed,participant demographics,organizational structures of teams,methodologies for IBS measurement,and correlations between brain synchronization and behavioral measurements.Results:fNIRS emerged as a non-invasive,cost-effective,and portable tool,predominantly used to assess IBS in pair-based tasks with a variety of participant demographics.Wavelet transform coherence was the primary method used for measuring synchronization,particularly in the prefrontal brain region.A consistent correlation was found between increased brain synchronization and enhanced team performance,underscoring the potential of fNIRS in understanding and optimizing team dynamics.Conclusion:This review establishes fNIRS as a promising tool for investigating the neural mechanisms underlying team cooperation,providing invaluable insights for potential applications in surgical settings.While acknowledging the limitations in the current literature,the review highlights the need for further research with larger sample sizes and varied task complexities to solidify the understanding of IBS and its impact on team performance.The ultimate goal is to leverage fNIRS in assessing and improving surgical team dynamics,contributing to improved patient outcomes and safety.
文摘In this work, three-dimensional molecular dynamics simulation is carried out to elucidate the nanoindentation behaviour of single crystal Ni. The substrate indenter system is modelled using hybrid interatomic potentials including the manybody potential （embedded atom method） and two-body Morse potential. The spherical indenter is chosen, and the simulation is performed for different loading rates from 10 m/s to 200 m/s. Results show that the maximum indentation load and hardness of the system increase with the increase of velocity. The effect of indenter size on the nanoindentation response is also analysed. It is found that the maximum indentation load is higher for the large indenter whereas the hardness is higher for the smaller indenter. Dynamic nanoindentation is carried out to investigate the behaviour of Ni substrate to multiple loading-unloading cycles. It is observed from the results that the increase in the number of loading unloading cycles reduces the maximum load and hardness of the Ni substrate. This is attributed to the decrease in recovery force due to defects and dislocations produced after each indentation cycle.
基金Natural Science Foundation of Heilongjiang Province of China(Grant No.YQ2022F012)the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2023010)to provide fund for conducting experiments.
文摘Aiming at the missile avoidance problem of the unmanned aerial vehicle(UAV)in complex obstacle environments,this work proposes a collision-avoidance method based on receding horizon optimization.The proposed method generated a specific trajectory for the UAV to effectively induce the proportional navigation missile to successfully intercept the obstacle,thereby accomplishing the evasive maneuver.The evasive maneuver was divided into two distinct stages,namely the collision-inducing phase and the fast departure phase.The obstacle potential field-based target selection algorithm was employed to identify the most appropriate target obstacle,while the induced trajectory was determined through a combination of receding horizon optimization and the hp-adaptive pseudo-spectral method.Simulation experiments were carried out under three different types of obstacle environments and one multiobstacle environment,and the simulation results show that the method proposed in this paper greatly improves the success rate of UAV evasive maneuvers,proving the effectiveness of this method.
基金the financial support from the China Scholarship Council(Grant No.202106370009)and Alberta Innovate Graduate Student Scholarship.
文摘Objective While there is consensus regarding a positive effect of video gaming on dexterity,little is known regarding how much traditional laparoscopic practice can or should be substituted with video gaming.This study was designed to assess the effects of varying the amount of traditional practice in a lap box trainer and video gaming on performance in two fundamentals of laparoscopic surgery core tasks.Methods Undergraduate and medical students were recruited and randomized into one of four groups:a control group,a lap box group,a video game group,and a combined group with 50%of the time allocated to each modality.Performance in the peg transfer and precision cutting tasks was assessed both prior to and following the 6 training sessions.Results Peg transfer performance significantly improved in the lap box group(168.4±70.6 s vs.332.9±178.2 s,p<0.001),video game group(176.7±53.3 s vs.300.0±101.2 s,p<0.001)and combined group(214.2±86.9 s vs.406.8±239.5 s,p=0.002)after training.Similar improvements were also observed in precision cutting performance in the lap box group(413.1±138.4 s vs.614.3±211.4 s,p=0.002),video game group(434.1±150.8 s vs.609.2±233.2 s,p=0.007)and combined group(469.2±185.3 s vs.663.8±296.3 s,p=0.020).When analyzing improvements in performance across three different training groups compared with the control group,we found that both the lap box group(p<0.001)and the combined group(p<0.001)showed better improvement in both tasks,and the video game group had significantly better outcomes in the precision cutting task(p=0.003).Conclusion Traditional lap box training remains the most effective method for improving the performance of simulated laparoscopic surgery.Video games can be encouraged to enhance skills retention and supplement simulated practice outside of a formal training curriculum.
基金the National Natural Science Foundation of China(Nos.51775137 and 51875127)。
文摘A Mg-Gd-Y-Zn-Zr magnesium alloy with different initial states was extruded under different extrusion parameters.The effect of solution treatment and extrusion parameters on the microstructure,texture and mechanical properties were analyzed in detail,and the abnormal texture formation and strengthening mechanism was revealed.When extruded at low temperature and small extrusion ratio,the bimodal microstructure consisting of fine dynamically recrystallized grains and coarse deformed grains occurred both in the as-cast alloy and solution-treated alloy.When the extrusion temperature and extrusion ratio were increased,the amount and size of dynamically recrystallized grains increased and the grain size of the solution-treated alloy showed higher growth rate.Furthermore,an abnormal texture with<0001>parallel with extrusion direction developed due to the occurrence of non-basal slip and continuous dynamic recrystallization.This could be enhanced by solution treatment,high temperature,and large extrusion ratio.Both the as-cast alloy and solution-treated alloy exhibited the highest tensile strength after extrusion at 300℃with an extrusion ratio of 9.Grain refinement was the main strengthening mechanism utilized in both the as-cast alloy and the solution-treated alloy.Work hardening played an important role in the sample extruded at low temperature and small extrusion ratio,with the highest contribution of about 33 MPa after extrusion at 300℃with an extrusion ratio of 9.Texture strengthening contributed more in the sample extruded at high temperature and large extrusion ratio,but no more than 24.1 MPa.Solution strengthening was another strengthening mechanism in the extruded as-cast alloy,especially at high temperature and large extrusion ratio(no more than 9 MPa).
文摘In the current study, streak camera was used to find concentricity of the assembly during detonation,investigate and compare shock front within the high explosive and behavior of the shock front on the surface of the liner, one containing wave shaper and the other without wave shaper. Streaks revealed that the whole assembly was concentric till the formation of the jet. Observed streaks vindicate the uniform propagation of shock front in both the cases. Results obtained for shock front velocities are in agreement with those obtained from simulations. In the presence of wave shaper higher shock front velocity was observed both in simulation and experiment. Simulation without wave-shaper showed that shock front struck the copper cone at grazing angle while in the presence of wave-shaper it struck at an angle of 125.
基金This work is supported by the National Key Research and Development Program of China under Grant 2017YFB1002304the China Scholarship Council under Grant 201906465021.
文摘Syndrome differentiation is the core diagnosis method of Traditional Chinese Medicine(TCM).We propose a method that simulates syndrome differentiation through deductive reasoning on a knowledge graph to achieve automated diagnosis in TCM.We analyze the reasoning path patterns from symptom to syndromes on the knowledge graph.There are two kinds of path patterns in the knowledge graph:one-hop and two-hop.The one-hop path pattern maps the symptom to syndromes immediately.The two-hop path pattern maps the symptom to syndromes through the nature of disease,etiology,and pathomechanism to support the diagnostic reasoning.Considering the different support strengths for the knowledge paths in reasoning,we design a dynamic weight mechanism.We utilize Naïve Bayes and TF-IDF to implement the reasoning method and the weighted score calculation.The proposed method reasons the syndrome results by calculating the possibility according to the weighted score of the path in the knowledge graph based on the reasoning path patterns.We evaluate the method with clinical records and clinical practice in hospitals.The preliminary results suggest that the method achieves high performance and can help TCM doctors make better diagnosis decisions in practice.Meanwhile,the method is robust and explainable under the guide of the knowledge graph.It could help TCM physicians,especially primary physicians in rural areas,and provide clinical decision support in clinical practice.
文摘In this paper,the node based smoothed-strain Abaqus user element(UEL)in the framework of finite element method is introduced.The basic idea behind of the node based smoothed finite element(NSFEM)is that finite element cells are divided into subcells and subcells construct the smoothing domain associated with each node of a finite element cell[Liu,Dai and Nguyen-Thoi(2007)].Therefore,the numerical integration is globally performed over smoothing domains.It is demonstrated that the proposed UEL retains all the advantages of the NSFEM,i.e.,upper bound solution,overly soft stiffness and free from locking in compressible and nearly-incompressible media.In this work,the constant strain triangular(CST)elements are used to construct node based smoothing domains,since any complex two dimensional domains can be discretized using CST elements.This additional challenge is successfully addressed in this paper.The efficacy and robustness of the proposed work is obtained by several benchmark problems in both linear and nonlinear elasticity.The developed UEL and the associated files can be downloaded from https://github.com/nsundar/NSFEM.
基金Funding from project PID2019-111285RB-I00awarded by the Spanish Ministry of Science,Innovation and Universities,is acknowledged+1 种基金W.C.Xu gratefully acknowledges the financial support from the National Natural Science Foundation of China under Grant No.51775137X.Z.Jin acknowledges the financial support from the China Scholarship Council.
文摘This work aims to understand the inefficiency of nanoprecipitates to strengthen a weakly textured,polycrystalline Mg-Gd-Y-Zr alloy.An experimental micromechanical approach consisting on micropillar compression combined with analytical electron microscopy is put in place to analyze the effect of nanoprecipitation on soft and hard basal slip and twinning in individual grains with different orientations.This study shows that,in grains that are favorably oriented for basal slip(“soft”basal slip),aging leads to extreme localization due to the ability of basal dislocations to shear the nanoparticles,resulting overall in the softening of basal systems.Additionally,in grains in which the c-axis is almost perpendicular to the compression axis,prismatic slip dominates deformation in the solid solution state and nanoprecipitation favors twinning due to the concomitant lattice solute depletion.Finally,in grains oriented with their c-axis making an angle of about 5-7°with respect to the compression axis,which deform mainly by“hard”basal slip,precipitation leads to the strengthening of basal systems in the absence of obvious localization.This work reveals that the poor hardening response of the polycrystalline alloy is related to the capability of basal dislocations to shear the nanoparticles,in the absence of Orowan looping events,and to the associated basal slip localization.
基金Supported by the Special Fund of Central University Basic Scientific Research Fee(No.HEUCFD1415)
文摘In light of the problem of radiolysis of the solvent system in PUREX(plutonium uranium recovery by extraction) process, γ and α irradiation stabilities of tributylphosphate(TBP)/n-dodecane/nitric acid system were studied using60 Co γ-rays and α particles from238 Pu. The main degradation products, dibutyl phosphate(HDBP)and monobutyl phosphate(H2MBP) were detected by the gas chromatography-mass spectrometry(GC-MS),and the degradation products that could not be easily removed by the washing procedure were measured by the Pu retention. Effects of the absorbed dose, the HNO3 concentration, and the cumulative dose on the irradiation stability of the systems were investigated. The yields of HDBP, H2 MBP and the Pu retention increased with the absorbed dose. The HNO3 concentration affected significantly on the yield of HDBP, but had little impact on the output of H2 MBP and Pu retention. For a similar absorbed dose, the Pu retention of the solvent by alpha irradiation is larger than that by gamma irradiation.
基金supported by the Higher Education Commission (HEC) of Pakistan (Grant No. +923445490402)
文摘In the present work, three-dimensional molecular dynamics simulation is carried out to elucidate the nanoinden- tation behaviors of CuZr Bulk metallic glasses （BMGs）. The substrate indenter system is modeled using hybrid interatomic potentials including both many-body Finnis Sinclair （FS） and two-body Morse potentials. A spherical rigid indenter （diameter= 60 A（1 A = 10 ^-10 m）） is employed to simulate the indentation process. Three samples of BMGs including Cu25Zr75, CusoZr50, and Cu75Zr25 are designed and the metallic glasses are formed by rapid cooling from the melt state at about 2000 K. The radial distribution functions are analyzed to reveal the dynamical evolution of the structure of the atoms with different compositions and different cooling rates. The mechanical behavior can be well understood in terms of load-depth curves and Hardness-depth curves during the nanoindentation process. Our results indicate a positive linear relationship between the hardness and the Cu concentration of the BMG sample. To reveal the importance of cooling rate provided during the processing of BMGs, we investigate the indentation behaviors of CusoZr50 at three different quenching rates. Nanoindentation results and radial distribution function （RDF） curves at room temperature indicate that a sample can be made harder and more stable by slowing down the quenching rate.
基金funded by the Alberta Jobs,Economy and Innovation Ministry's Major Initiatives Fund to Dr.Zheng(MIF01 T4 P1 Zheng)the Royal College of Physicians and Surgeons of Canada Medical Education Research Award to Dr.Zheng(RCPSC 16/MERC-09).
文摘Objective:Surgeons are required to wear heavy personal protective equipment while delivering care to patients during the COVID-19 pandemic.We examined the impact of wearing double gloves on surgeons’performance in laparoscopic surgery.Methods:Eleven surgeons-in-training at the Surgical Simulation Research Lab of the University of Alberta were recruited to perform laparoscopic cutting tasks in simulation while wearing none,one pair,and two pairs of surgical gloves.Forces applied to laparoscopic instruments were measured.Results:Wearing gloves prolonged task times(one pair of gloves:301.6±61.7 s;two pairs of gloves:295.8±65.3 s)compared with no gloves(241.7±46.9 s;p=0.043).Wearing double gloves increased cutting errors(20.4±5.1 mm^(2))compared with wearing one pair of gloves(16.9±5.5 mm^(2))and no gloves(14.4±4.6 mm^(2);p=0.030).Wearing gloves reduced the peak force(one pair of gloves:2.4±0.7 N;two pairs of gloves:2.7±0.6 N;no gloves:3.4±1.4 N;p=0.049),and the total force(one pair of gloves:10.1±2.8 N;two pairs of gloves:10.3±2.6 N;no glove:12.6±1.9 N;p=0.048)delivered onto lapa-roscopic scissors compared with wearing no glove.Conclusion:The combined effects of wearing heavy gloves and using tools reduced the touching sensation,which limited the surgeons’confidence in performing surgical tasks.Increasing practice in simulation is suggested to allow surgeons to overcome difficulties brought by personal protective equipment.
基金Project supported by the Deanship of Scientific Research at King Saud University,Saudi Arabia(Grant No.RGP-VPP-311)
文摘We employ ab-initio calculations to analyze the mechanical, electronic, optical and also thermoelectric properties associated with AGeO3（A = Ca, Sr） compounds. The full-potential linearized augmented plane wave（FP-LAPW） technique in the generalized gradient approximation（GGA-PBEsol） and the lately designed Tran-Blaha-modified Becke-Johnson exchange potential are utilized to examine the mechanical and optoelectronic properties respectively. To explore the thermoelectric quality, we use the semi-classical Boltzmann transport theory. The particular structural stabilities regarding AGeO3（A = Ca, Sr） materials are validated simply by computations from the elastic constants. The energy band structural framework and the density of states are displayed to indicate indirect bandgap under ambient conditions. The particular computed optical attributes that reveal prospective optoelectronic applications are usually elucidated simply by studying ε1（0） and also Eg, which can be connected by means of Penn＇s design. The optical details uncover the actual suitability to power ranging products. Finally, the Boltz Tra P code is executed to analyze the actual thermoelectric properties, which usually presents that the increase of internal temperatures can enhance the electric conductivity, thermal conductivity and also the power factor, whilst Seebeck coefficient decreases. Therefore, the studied materials will also be ideal for thermoelectric products to understand helpful option for alternative energy resources.
基金The author appreciates the support from Francesca Seal for assisting with data collection and David Pinzon for technical assistance throughout the project.This work was funded by the Wynne Rigal Summer Research Award to Bo Bao,Faculty of Medicine and Dentistry,University of Alberta and the Royal Alexandra Hospital Foundation(Grant no.Res00066823)MIS Research Funds to Dr.Bin Zheng.
文摘Aim:To examine the significance of team collaboration in the context of complex laparoscopic surgery,laparoscopic tasks performed by single operators are compared against that of dyad teams.Methods:The laparoscopic tasks require subjects to reach,grasp and transport a ring through a rollercoaster obstacle using a pair of laparoscopic graspers.The task was performed either bimanually(using both hands)or unimanually(using their preferred hands)in a dyad team.Results:Twelve participants completed all the tasks.The dyad teams recorded significantly greater number of anticipatory movements than individuals who performed the task bimanually(p<0.05).However,there is no significant difference in the task completion time(p=0.701)and the number of errors(p=0.860)recorded between the dyad and the bimanual group.Conclusion:Compared to a single operator,dyad operators performed the task with greater number of anticipatory movements.The increased movement synchronization can help benefit surgical education and team training.
基金the Higher Education Commission(HEC)of Pakistan for providing research funding under Project No.:20-14784/NRPU/R&D/HEC/2021.S.A.K.acknowledge the QM4ST project financed by the Ministry of Education of the Czech Republic grant no.CZ.02.01.01/00/22_008/0004572,co-funded by the European Regional Development Fund.
文摘The versatile,and tunable surface chemistry of two-dimensional(2D)MXenes coupled with their distinct properties including hydrophilic nature,favorable ion transport and metallic conductivity make them an ideal candidate for energy storage devices.Modifying surface terminations by doping heteroatom is an efficient approach to improve layer spacing and electrochemical active sites of the MXenes.However,nitrogen doping in 2D materials has been an effective way to enhance their electrochemical characteristics.In this study,N-Nb2CTx MXene was synthesized by utilizing the hydrothermal method in which nitrogen doping in MXene was confirmed through several characterization techniques.Tuning of MXene surface by a cost-effective strategy has shown improved performance for energy storage.After doping nitrogen in Nb2CTx MXene,it has shown enhanced pseudocapacitance performance in 1 M potassium hydroxide(KOH),elevating the electrochemical properties.N-Nb2CTx MXene has displayed a better specific capacitance of up to 640 F·g-1 while pristine Nb2CTx MXene has shown 276 F·g-1 from the cyclic voltammogram(CV)at a scan rate of 5 mV·s-1.In addition,an asymmetric device of activated carbon/N-Nb2CTx was assembled for real-world applications,it has exhibited refined results.The asymmetric device has shown remarkable cyclic stability of 90%capacity retention at a current density of 5 A·g-1 for 5000 cycles.Additionally,the detailed density functional theory(DFT)calculations support the stability of nitrogen replacing the fluorine functional group,complementing the experiment.
文摘In the recent years, the phase field method for simulating fracture problems has received considerable attention. This is due to the salient features of the method: 1) it can be incorporated into any conventional finite element software;2) has a scalar damage variable is used to represent the discontinuous surface implicitly and 3) the crack initiation and subsequent propagation and branching are treated with less complexity. Within this framework, the linear momentum equations are coupled with the diffusion type equation, which describes the evolution of the damage variable. The coupled nonlinear system of partial differential equations are solved in a 'staggered? approach. The present work discusses the implementation of the phase field method for brittle fracture within the open-source finite element software, FEniCS. The FEniCS provides a framework for the automated solutions of the partial differential equations. The details of the implementation which forms the core of the analysis are presented. The implementation is validated by solving a few benchmark problems and comparing the results with the open literature.
