虚拟仿真实验在医学遗传学实验教学中的探索与实践

医学遗传学是一门实践性很强的课程,理论教学和实验教学必须相辅相成、相互成就。然而,受实验场地、医学伦理、实验内容抽象、生物安全等现实条件的限制,实验教学难以顺利开展,无法满足新医科背景下医学生综合能力的培养要求。西安交通大学医学遗传学实验教学采用“线上与线下相结合,虚拟与实操相结合”的方式,以理论教学指导虚拟仿真实验的操作,再以虚拟仿真实验的经验及教训指导线下实体动物实验的操作,以此帮助学生获得临床沉浸式体验,使学生在实体动物实验过程中提高动手能力和分析解决实际问题的能力。

基于VR技术的PBL混合教学模式在法医物证学教学中的探索

PBL教学法作为当代教学中一种新型教学方式,不仅能够培养学生创新思维及创新能力,也可提高学生解决实际问题的能力,对法医物证学教学的改革与发展具有重要意义和实用价值。在教育信息化的不断推进下,虚拟现实技术(virtual reality,VR)作为高科技手段之一,因其具有沉浸性、交互性、想象性和多感知性等特点,也逐渐渗透到传统教育改革领域当中。该研究探讨了VR技术结合PBL教学法应用于法医物证学教学改革的可行性,为VR技术在法医物证学教学中的应用提供理论依据和实践参考。

基于BWOA-SVM的尾矿库风险评价

为及时掌握尾矿库风险状态,降低尾矿库溃坝造成的人员伤亡、财产损失和环境污染,建立尾矿库风险评价模型具有十分重要的现实意义。首先,构建尾矿库风险等级评价指标体系,确定指标分级标准;其次,利用博弈论将层次分析法和熵值法结合起来确定指标组合权重;再次,利用rand()函数生成伪随机数作为模型训练数据库,将权重与训练数据对应组合,建立物元可拓模型计算尾矿库所属风险等级;最后构建BWOA-SVM(改进鲸鱼算法(BWOA)优化的支持向量机(SVM)模型)模型对风险等级预测,对该模型进行训练,得到模型预测准确率为98%,与传统SVM相比提升了44.9%。采用山西东沟尾矿库数据验证模型的可行性,将尾矿库数据输入训练好的模型中得到该尾矿库等级为Ⅱ级,与实际情况相同,验证了所提方法的可行性,通过该方法可以确定尾矿库的风险等级,从而为尾矿库风险分级管理提供依据。

Evaluation of roof cutting by directionally single cracking technique in automatic roadway formation for thick coal seam mining

Automatic roadway formation by roof cutting is a sustainable nonpillar mining method that has the potential to increase coal recovery,reduce roadway excavation and improve mining safety.In this method,roof cutting is the key process for stress relief,which significantly affects the stability of the formed roadway.This paper presents a directionally single cracking(DSC)technique for roof cutting with considerations of rock properties.The mechanism of the DSC technique was investi-gated by explicit finite element analyses.The DSC technique and roof cutting parameters were evaluated by discrete element simulation and field experiment.On this basis,the optimized DSC technique was tested in the field.The results indicate that the DSC technique could effectively control the blast-induced stress distribution and crack propagation in the roof rock,thus,achieve directionally single cracking on the roadway roof.The DsC technique for roof cutting with optimized parameters could effectively reduce the deformation and improve the stability of the formed roadway.Field engineering application verified the feasibility and effectiveness of the evaluated DSC technique for roof cutting.

Interaction between in situ stress states and tectonic faults:A comment

Understanding the in situ stress state is crucial in many engineering problems and earth science research.The present article presents new insights into the interaction mechanism between the stress state and faults.In situ stresses can be influenced by various factors,one of the most important being the existence of faults.A fault could significantly affect the value and direction of the stress components.Reorientation and magnitude changes in stresses exist adjacent to faults and stress jumps/discontinuities across the fault.By contrast,the change in the stress state may lead to the transformation of faulting type and potential fault reactivation.Qualitative fault reactivation assessment using characteristic parameters under the current stress environment provides a method to assess the slip tendency of faults.The correlation between in situ stresses and fault properties enhances the ability to predict the fault slip tendency via stress measurements,which can be used to further refine the assessment of the fault reactivation risk.In the future,stress measurements at greater depths and long-term continuous real-time stress monitoring near/on key parts of faults will be essential.In addition,much attention needs to be paid to distinguishing the genetic mechanisms of abnormal stress states and the type and scale of stress variations and exploring the mechanisms of pre-faulting anomaly and fault reactivation.

Sulfate diffusion in coal pillar:experimental data and prediction model

The stability of coal pillar dams is crucial for the long-term service of underground reservoirs storing water or heat.Chemi-cal damage of coal dams induced by ions-atttacking in coal is one of the main reasons for the premature failure of coal dams.However,the diffusion process of harmful ions in coal is far from clear,limiting the reliability and durability of coal dam designs.This paper investigates sulfate diffusion in coal pillar through experimental and analytical methods.Coal specimens are prepared and exposed to sulfate solutions with different concentrations.The sulfate concentrations at different locations and time are measured.Based on experimental data and Fick's law,the time-dependent surface concentration of sulfate and diffusion coefficient are determined and formulated.Further,an analytical model for predicting sulfate diffusion in coal pillar is developed by considering dual time-dependent characteristics and Laplace transformations.Through comparisons with experimental data,the accuracy of the analytical model for predicting sulfate diffusion is verified.Further,sulfate diffusions in coal dams for different concentrations of sulfate in mine water are investigated.It has been found that the sulfate concen-tration of exposure surface and diffusion coefficient in coal are both time-dependent and increase with time.Conventional Fick's law is not able to predict the sulfate diffusion in coal pillar due to the dual time-dependent characteristics.The sulfate attacking makes the coal dam a typical heterogeneous gradient structure.For sulfate concentrations 0.01-0.20 mol/L in mine water,it takes almost 1.5 and 4 years for sulfate ions to diffuse 9.46 and 18.92 m,respectively.The experimental data and developed model provide a practical method for predicting sulfate diffusion in coal pillar,which helps the service life design of coal dams.

Technology strategies to achieve carbon peak and carbon neutrality for China's metal mines

Greenhouse gas(GHG)emissions related to human activities have significantly caused climate change since the Industrial Revolution.China aims to achieve its carbon emission peak before 2030 and carbon neutrality before 2060.Accordingly,this paper reviews and discusses technical strategies to achieve the“dual carbon”targets in China’s metal mines.First,global carbon emissions and emission intensities from metal mining industries are analyzed.The metal mining status and carbon emissions in China are then examined.Furthermore,advanced technologies for carbon mitigation and carbon sequestration in metal mines are reviewed.Finally,a technical roadmap for achieving carbon neutrality in China’s metal mines is proposed.Findings show that some international mining giants have already achieved their carbon reduction targets and planned to achieve carbon neutrality by 2050.Moreover,improving mining efficiency by developing advanced technologies and replacing fossil fuel with renewable energy are two key approaches in reducing GHG emissions.Green mines can significantly benefit from the carbon neutrality process for metal mines through the carbon absorption of reclamation vegetations.Geothermal energy extraction from operating and abandoned metal mines is a promising technology for providing clean energy and contributing to the carbon neutrality target of China’s metal mines.Carbon sequestration in mine backfills and tailings through mineral carbonation has the potential to permanently and safely store carbon dioxide,which can eventually make the metal mining industry carbon neutral or even carbon negative.

Roughness characterization and shearing dislocation failure for rock-backfill interface

Shearing dislocation is a common failure type for rock–backfill interfaces because of backfill sedimentation and rock strata movement in backfill mining goaf.This paper designed a test method for rock–backfill shearing dislocation.Using digital image techno-logy and three-dimensional(3D)laser morphology scanning techniques,a set of 3D models with rough joint surfaces was established.Further,the mechanical behavior of rock–backfill shearing dislocation was investigated using a direct shear test.The effects of interface roughness on the shear–displacement curve and failure characteristics of rock–backfill specimens were considered.The 3D fractal dimen-sion,profile line joint roughness coefficient(JRC),profile line two-dimensional fractal dimension,and the surface curvature of the frac-tures were obtained.The correlation characterization of surface roughness was then analyzed,and the shear strength could be measured and calculated using JRC.The results showed the following:there were three failure threshold value points in rock–backfill shearing dis-location:30%–50%displacement before the peak,70%–90%displacement before the peak,and 100%displacement before the peak to post-peak,which could be a sign for rock–backfill shearing dislocation failure.The surface JRC could be used to judge the rock–backfill shearing dislocation failure,including post-peak sliding,uniform variations,and gradient change,corresponding to rock–backfill disloca-tion failure on the field site.The research reveals the damage mechanism for rock–backfill complexes based on the free joint surface,fills the gap of existing shearing theoretical systems for isomerism complexes,and provides a theoretical basis for the prevention and control of possible disasters in backfill mining.