Introduction: The evaluation of academic stress in medical students and residents is a topic of significant interest, given the considerable challenges they face during their learning process with traditional teaching...Introduction: The evaluation of academic stress in medical students and residents is a topic of significant interest, given the considerable challenges they face during their learning process with traditional teaching methods. The use of technologies like virtual reality presents an opportunity to enhance their skills through simulations and training. The main objective of this study is to qualitatively assess the stress levels experienced by medical students and residents by integrating virtual reality into their current learning methods, aiming to improve their ability to manage stressors in their practice. Material and Methods: A questionnaire was conducted with 12 medical students and 12 Traumatology and orthopedics residents. The purpose of the questionnaire was to evaluate the levels of academic stress using the SISCO inventory. The stress levels were calculated by transforming average values into percentages, and the following criteria were assigned: 0 to 33% for Mild Stress, 34 to 66% for Moderate Stress, and 67 to 100% for Deep Stress. Then, a virtual reality class focused on spine surgery was provided. Both medical students and residents were trained using the Non Nocere SharpSurgeon software platform and Oculus Quest 2 virtual reality glasses. At the end of the session, a second questionnaire related to the practice with virtual reality was conducted with the same evaluation criteria and a comparative analysis was carried out. Results: 12 undergraduate students from Hospital Angeles Mexico, CDMX and 12 traumatology and orthopedics residents at Hospital Santa Fe, Bogota were evaluated. The students in CDMX reported an average qualitative stress of 28.50% during habitual practices, which decreased to an average of 14.67% after virtual reality practice. Residents in Bogotá experienced an average qualitative stress of 30.50% with their current learning methods but this reduced to an average of 13.92% after using virtual reality. These findings indicate that the use of virtual reality has a positive impact on reducing stress levels qualitatively. Conclusions: The use of virtual reality as a learning method for medical students and residents qualitatively improves stress levels. Further studies are required to define the potential uses of Virtual Reality to improve learning methods and emotional state in medical students and residents and for a quantitative assessment to validate the training as certified learning methods.展开更多
It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mo...It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results.展开更多
Cross-section deformation is one of important factors affecting the quality of tube formation, and the tube＇s capability of transporting liquid and gas will be reduced because of the cross-section ellipse deformation...Cross-section deformation is one of important factors affecting the quality of tube formation, and the tube＇s capability of transporting liquid and gas will be reduced because of the cross-section ellipse deformation due to the effect of shear load in plastic bending process. When the tube is bent, the extrados-wall bears the tension stress and the intrados-wall bears the compression stress, synchronously the cross-section is affected by the circumferential stress. According to the above, the distribution function and curve of tangential stress can be obtained according to force balance differential equations on circumferential direction and Trasca rule. Subsequently the real state and virtual state moment equations were established, a new method was presented adopting the virtual principle of deformation system to calculate the x-axis and y-axis displacement of arbitrary point on cross-section. So the major and minor axes of deformed cross-section can be calculated according to the displacements of each point, and the variety value of major and minor axes will be obtained further. Finally the theoretical calculating result is compared with NC tube rotary-bending experiment results to verify the rationality of theoretical analysis, and the cross-section deformation rule of thin-walled tube can be received.展开更多
针对双有源桥DC-DC(dual active bridge,DAB)变换器中存在较大的电流应力现象,提出一种基于功率补偿的电流应力改进控制方法。通过建立DAB的电流应力、传输功率与相移量之间的函数关系,利用拉格朗日乘数法建立电流应力的优化数学模型,...针对双有源桥DC-DC(dual active bridge,DAB)变换器中存在较大的电流应力现象,提出一种基于功率补偿的电流应力改进控制方法。通过建立DAB的电流应力、传输功率与相移量之间的函数关系,利用拉格朗日乘数法建立电流应力的优化数学模型,从而推导出最优占空比组合,降低电流应力至最小值。通过引入一个虚拟分量对传输功率进行实时补偿控制,以满足系统在输入、输出突变情况下的快速响应能力,提高DAB的动态特性。最后,通过搭建Matlab/Simulink仿真模型进行验证,通过仿真结果表明:基于功率补偿的电流应力优化控制方法的动态响应特性和ZVS特性明显优于传统控制方法,且在减小电流应力的同时也降低了回流功率,进一步验证了优化控制方法的正确性和优越性。展开更多
目的系统评价虚拟现实技术应用于心脏康复患者的效果。方法计算机检索Embase、Web of Science、PubMed、Cochrane Library、万方数据、中国知网数据库,搜集有关虚拟现实技术在心脏康复患者中应用的随机对照试验研究,检索时限均为建库至2...目的系统评价虚拟现实技术应用于心脏康复患者的效果。方法计算机检索Embase、Web of Science、PubMed、Cochrane Library、万方数据、中国知网数据库,搜集有关虚拟现实技术在心脏康复患者中应用的随机对照试验研究,检索时限均为建库至2021年11月19日。由2名研究者独立检索并筛选文献,进行文献质量评价后,采用RevMan5.4软件进行Meta分析。结果共纳入12篇文献,包括597例患者。Meta分析结果显示,虚拟现实技术降低患者抑郁[SMD=-0.57,95%CI(-0.88,-0.26),P<0.05]、焦虑[SMD=-0.38,95%CI(-0.69,-0.07),P<0.05]及压力[SMD=-0.76,95%CI(-1.08,-0.45),P<0.05],提高患者满意度[SMD=0.55,95%CI(0.24,0.86),P<0.05]的效果显著优于传统心脏康复干预;对患者依从性的改善差异无统计学意义[OR=0.86,95%CI(0.08,8.37),P=0.86]。结论虚拟现实技术应用于心脏康复能改善患者心理状态,提高患者满意度,但在改善患者心功能和依从性方面尚缺乏有力证据。受纳入研究数量和质量限制,上述结论尚待更多高质量研究予以验证。展开更多
文摘Introduction: The evaluation of academic stress in medical students and residents is a topic of significant interest, given the considerable challenges they face during their learning process with traditional teaching methods. The use of technologies like virtual reality presents an opportunity to enhance their skills through simulations and training. The main objective of this study is to qualitatively assess the stress levels experienced by medical students and residents by integrating virtual reality into their current learning methods, aiming to improve their ability to manage stressors in their practice. Material and Methods: A questionnaire was conducted with 12 medical students and 12 Traumatology and orthopedics residents. The purpose of the questionnaire was to evaluate the levels of academic stress using the SISCO inventory. The stress levels were calculated by transforming average values into percentages, and the following criteria were assigned: 0 to 33% for Mild Stress, 34 to 66% for Moderate Stress, and 67 to 100% for Deep Stress. Then, a virtual reality class focused on spine surgery was provided. Both medical students and residents were trained using the Non Nocere SharpSurgeon software platform and Oculus Quest 2 virtual reality glasses. At the end of the session, a second questionnaire related to the practice with virtual reality was conducted with the same evaluation criteria and a comparative analysis was carried out. Results: 12 undergraduate students from Hospital Angeles Mexico, CDMX and 12 traumatology and orthopedics residents at Hospital Santa Fe, Bogota were evaluated. The students in CDMX reported an average qualitative stress of 28.50% during habitual practices, which decreased to an average of 14.67% after virtual reality practice. Residents in Bogotá experienced an average qualitative stress of 30.50% with their current learning methods but this reduced to an average of 13.92% after using virtual reality. These findings indicate that the use of virtual reality has a positive impact on reducing stress levels qualitatively. Conclusions: The use of virtual reality as a learning method for medical students and residents qualitatively improves stress levels. Further studies are required to define the potential uses of Virtual Reality to improve learning methods and emotional state in medical students and residents and for a quantitative assessment to validate the training as certified learning methods.
文摘It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results.
基金supported by "Eleven Five Years Plan" Basic Research Item of National Defense of China (Grant No. B2220060048)
文摘Cross-section deformation is one of important factors affecting the quality of tube formation, and the tube＇s capability of transporting liquid and gas will be reduced because of the cross-section ellipse deformation due to the effect of shear load in plastic bending process. When the tube is bent, the extrados-wall bears the tension stress and the intrados-wall bears the compression stress, synchronously the cross-section is affected by the circumferential stress. According to the above, the distribution function and curve of tangential stress can be obtained according to force balance differential equations on circumferential direction and Trasca rule. Subsequently the real state and virtual state moment equations were established, a new method was presented adopting the virtual principle of deformation system to calculate the x-axis and y-axis displacement of arbitrary point on cross-section. So the major and minor axes of deformed cross-section can be calculated according to the displacements of each point, and the variety value of major and minor axes will be obtained further. Finally the theoretical calculating result is compared with NC tube rotary-bending experiment results to verify the rationality of theoretical analysis, and the cross-section deformation rule of thin-walled tube can be received.
文摘针对双有源桥DC-DC(dual active bridge,DAB)变换器中存在较大的电流应力现象,提出一种基于功率补偿的电流应力改进控制方法。通过建立DAB的电流应力、传输功率与相移量之间的函数关系,利用拉格朗日乘数法建立电流应力的优化数学模型,从而推导出最优占空比组合,降低电流应力至最小值。通过引入一个虚拟分量对传输功率进行实时补偿控制,以满足系统在输入、输出突变情况下的快速响应能力,提高DAB的动态特性。最后,通过搭建Matlab/Simulink仿真模型进行验证,通过仿真结果表明:基于功率补偿的电流应力优化控制方法的动态响应特性和ZVS特性明显优于传统控制方法,且在减小电流应力的同时也降低了回流功率,进一步验证了优化控制方法的正确性和优越性。
文摘目的系统评价虚拟现实技术应用于心脏康复患者的效果。方法计算机检索Embase、Web of Science、PubMed、Cochrane Library、万方数据、中国知网数据库,搜集有关虚拟现实技术在心脏康复患者中应用的随机对照试验研究,检索时限均为建库至2021年11月19日。由2名研究者独立检索并筛选文献,进行文献质量评价后,采用RevMan5.4软件进行Meta分析。结果共纳入12篇文献,包括597例患者。Meta分析结果显示,虚拟现实技术降低患者抑郁[SMD=-0.57,95%CI(-0.88,-0.26),P<0.05]、焦虑[SMD=-0.38,95%CI(-0.69,-0.07),P<0.05]及压力[SMD=-0.76,95%CI(-1.08,-0.45),P<0.05],提高患者满意度[SMD=0.55,95%CI(0.24,0.86),P<0.05]的效果显著优于传统心脏康复干预;对患者依从性的改善差异无统计学意义[OR=0.86,95%CI(0.08,8.37),P=0.86]。结论虚拟现实技术应用于心脏康复能改善患者心理状态,提高患者满意度,但在改善患者心功能和依从性方面尚缺乏有力证据。受纳入研究数量和质量限制,上述结论尚待更多高质量研究予以验证。
