Molecular dynamics study of primary radiation damage in TiVTa concentrated solid-solution alloy

The primary radiation damage in pure V and TiVTa concentrated solid-solution alloy(CSA)was studied using a molecular dynamics method.We have performed displacement cascade simulations to explore the generation and evolution behavior of irradiation defects.The results demonstrate that the defect accumulation and agglomeration in TiVTa CSA are significantly suppressed compared to pure V.The peak value of Frenkel pairs during cascade collisions in TiVTa CSA is much higher than that in pure V due to the lower formation energy of point defects.Meanwhile,the longer lifetime of the thermal spike relaxation and slow energy dissipation capability of TiVTa CSA can facilitate the recombination of point defects.The defect agglomeration rate in TiVTa CSA is much lower due to the lower binding energy of interstitial clusters and reduced interstitial diffusivity.Furthermore,the occurrence probability of dislocation loops in TiVTa CSA is lower than that in pure V.The reduction in primary radiation damage may enhance the radiation resistance of TiVTa CSA,and the improved radiation tolerance is primarily attributed to the relaxation stage and long-term defect evolution rather than the ballistic stage.These results can provide fundamental insights into irradiation-induced defects evolution in refractory CSAs.

DNA damage response-related immune activation signature predicts the response to immune checkpoint inhibitors: from gastrointestinal cancer analysis to pan-cancer validation

Objective: DNA damage response(DDR) deficiency has emerged as a prominent determinant of tumor immunogenicity. This study aimed to construct a DDR-related immune activation(DRIA) signature and evaluate the predictive accuracy of the DRIA signature for response to immune checkpoint inhibitor(ICI) therapy in gastrointestinal(GI) cancer.Methods: A DRIA signature was established based on two previously reported DNA damage immune response assays. Clinical and gene expression data from two published GI cancer cohorts were used to assess and validate the association between the DRIA score and response to ICI therapy. The predictive accuracy of the DRIA score was validated based on one ICI-treated melanoma and three pan-cancer published cohorts.Results: The DRIA signature includes three genes(CXCL10, IDO1, and IFI44L). In the discovery cancer cohort, DRIA-high patients with gastric cancer achieved a higher response rate to ICI therapy than DRIA-low patients(81.8% vs. 8.8%;P < 0.001), and the predictive accuracy of the DRIA score [area under the receiver operating characteristic curve(AUC) = 0.845] was superior to the predictive accuracy of PD-L1 expression, tumor mutational burden, microsatellite instability, and Epstein–Barr virus status. The validation cohort demonstrated that the DRIA score identified responders with microsatellite-stable colorectal and pancreatic adenocarcinoma who received dual PD-1 and CTLA-4 blockade with radiation therapy. Furthermore, the predictive performance of the DRIA score was shown to be robust through an extended validation in melanoma, urothelial cancer, and pan-cancer.Conclusions: The DRIA signature has superior and robust predictive accuracy for the efficacy of ICI therapy in GI cancer and pancancer, indicating that the DRIA signature may serve as a powerful biomarker for guiding ICI therapy decisions.

LID设施布局对城市径流与污染负荷影响评估

关于低影响开发(LID)空间布局对水量水质控制效果影响的研究较为缺乏。针对上述问题,以郑州市中原区为对象,基于SWMM模型原理构建布设LID设施的研究区城市水量水质模型。所提模型依据城市综合径流系数的经验值以及研究区实际情况,将中原区划分为城市建筑高、中、低密集区,并在研究区高、中、低密集子汇水区布设不同比例的LID设施(S1~S5),计算不同雨量级别下不同空间格局下的LID设施对水量水质的控制效果。结果表明:随着雨量级别的增大,LID方案的径流总量削减率、峰值流量削减率和TSS负荷削减率不断减小。在降雨级别为暴雨、大雨和中雨时,在高、中、低密集子汇水区布设占比分别为35%、35%和30%的LID方案(S5),其径流总量削减率超过80%,峰值流量削减率超过70%,且TSS负荷削减率超过50%。从各事件下水量与水质综合指标评估来看,该方案表现最佳。

基于遗传算法的LID设施优化布设

在系统化全域推进海绵城市建设的背景下,低影响开发设施布设对城市雨洪过程具有重要影响。以江苏省宜兴市区为研究对象基于暴雨洪水管理模型SWMM建立研究区雨洪模型,考虑以径流总量削减率、悬浮物负荷削减率、生命周期成本、低影响开发设施占地面积建立综合目标函数,通过权重调整目标参数的优先级,运用遗传算法求解得到不同情景下低影响开发设施的最佳布设方案。结果表明:①在同等权重条件下,生命周期成本对优化计算的影响远大于面积,径流总量削减率与悬浮物负荷削减率影响较小;②位于管道上游的小面积汇水区内低影响开发设施的优化布设易受降雨重现期影响。研究成果可为海绵城市建设中低影响开发设施的优化布设及城市内涝防治研究提供参考。

Mechanical properties and damage characteristics of solidified body-coal combination in continuous driving and gangue backfilling

Recovery of the coal buried under buildings,railways and water bodies and the residual coal in irregularly arranged fully mechanized mining faces is a common engineering problem facing underground coal mining.In this study,a mining technology of continuous driving and gangue backfilling(CDGB)was proposed.The technology,which can not only alleviate ground subsidence and gangue discharge,but also release the above-mentioned coals,contributes to green and efficient sustainable development of mining.The stability of the system of the solidified body-reserved coal pillar combination(S-C combination)is crucial to the CDGB technology.Therefore,it is of great significance to explore the mechanical and damage characteristics of S-C combination in the synergistic bearing process.First,four sets of differentshaped S-C combination specimens were fabricated and a S-C combination bearing structure in CDGB was constructed to explore the differences in mechanical characteristics and damage modes of different-shaped S-C combination specimens during CDGB.Subsequently,their surface strain field evolutions and acoustic emission(AE)response characteristics in the load-bearing process were obtained with the aid of the digital image correlation technique and the AE signal monitoring system.Furthermore,a damage evolution model based on AE parameters and mechanical parameters was established to clarify the damage evolution law.The following results were obtained:(1)The free area of S-C combination can serve as a quantitative index to evaluate the stability of the overburden control system;(2)The concept of critical value k of the free area was first proposed.When the free area exceeds the critical value k(free area ratio greater than 1.13),the deformation resistance and the free area changes becomes negatively correlated;(3)As the free area expands,the failure of the S-C combination specimen evolves from tensile failure to shear failure.The distribution characteristics of the axial strain field also verified such a change in the failure mode;(4)When the free area expands,the peak AE count gradually changes from“double peaks”to“a single peak”.In this process,the expansion of free area shortens the time for accumulating and releasing energy during loading.Micro cracks generated in the specimen change from a phased steep growth to a continuous increase,and the process in which micro cracks develop,converge,intersect and connect to form macro cracks accelerates.The damage evolution law concluded based on AE parameters and mechanical parameters can well characterize the damage evolution process of S-C combination,providing certain reference for the study on the synergistic bearing of S-C combination during CDGB.

基于多目标进化算法和SWMM的LID设施空间布局优化研究

针对传统算法无法满足低影响开发(LID)设施空间布局优化模型求解的性能要求的问题,以重庆秀山海绵城市建设区为研究区,基于MATLAB软件的platEMO4.0平台,对比分析了NSGA-Ⅱ、NSGA-Ⅲ、MOEAD、PICEA-g、MOEAPSL、CCMO与CAMOEA7种多目标进化算法对LID设施空间布局优化问题的求解结果与性能评价指标,并提出最佳方案。结果表明:新算法大部分性能指标优于传统算法,其中CCMO算法的多样性与收敛性最佳,而MOEAPSL算法的求解速度最快,搜索能力最强,且最优解数量最多;采用CCMO和MOEAPSL算法可获得研究区不同降雨重现期下的Pareto近似前沿,即LID设施空间布局的最优解集;以径流削减为控制目标的最佳方案在降雨重现期为5~100 a时径流总量控制率为67.23%~76.70%,洪峰流量削减率为66.42%~77.86%,LID单位面积建设成本为203.90~245.23元/m 2。

基于GWO-PSO算法的小尺度地区LID布设优化模型研究

【目的】海绵城市通过低影响开发(LID)雨水系统来降低降雨相关灾害的影响,合理的LID布设方案是开发效果的决定性因素。【方法】通过耦合暴雨洪水管理模型(SWMM)和灰狼粒子群算法(GWO-PSO),建立了小尺度地区LID优化布设模型。GWO-PSO算法中粒子进行了基于社会等级制度的位置策略调整,以此得到更好地寻优性能。模型依据排放口流量,完成参数自动率定,并以洪峰流量为目标,经济成本为约束,求解雨水花园、生物网格、绿色屋顶和透水铺装四种包含相互独立与制约关系的LID设施的优化布设方案。【结果】将该模型应用于某试点小区,在预算182万元的情况下,得到5 a、10 a、20 a和50 a重现期下的布设方案,洪峰削减率分别为61.5%、53.2%、42.4%和31.1%。【结论】结果表明:在小尺度地区进行LID建设时,需要考虑子汇水区面积的影响;对于道路汇水区,需要联系地理位置布设;在低重现期下,各LID设施调控效果均较好,而在高重现期下,绿色屋顶的承受能力最强,且需要更多预算进行削峰。

Energy‐based analysis of seismic damage mechanism of multi‐anchor piles in tunnel crossing landslide area

To study the damage mechanism of multi‐anchor piles in tunnel crossing landslide area under earthquake,the damping performance of multi‐anchor piles was discussed.The energy dissipation springs were used as the optimization device of the anchor head to carry out the shaking table comparison test on the reinforced slope.The Hilbert spectrum and Hilbert marginal spectrum were proposed to analyze the seismic damage mechanism of the multi‐anchor piles,and the peak Fourier spectrum amplitude(PFSA)was used to verify the effectiveness of the method.The results show that the seismic energy is concentrated in the high‐frequency component(30-40Hz)of the Hilbert spectrum and the low‐frequency component(12-30 Hz)of the marginal spectrum.This indicates that they can be combined with the distribution law of the PFSA to identify the overall and local dynamic responses of the multi‐anchored piles,respectively.The stretchable deformation of the energy‐dissipation springs improves the coordination of the multi‐anchor piles,resulting in better pile integrity.The damage mechanism of the multi‐anchor piles is elucidated based on the energy method:local damage at the top and middle areas of the multi‐anchor piles is mainly caused by the low‐frequency component(12-30 Hz)of the marginal spectrum under the action of 0.15g and 0.20g seismic intensities.As the seismic intensity increases to 0.30g,the dynamic response of the slope is further amplified by the high‐frequency component(30-40 Hz)of the Hilbert energy spectrum,which leads to the overall damage of the multi‐anchor piles.

基于SWMM模型与NSGA-Ⅱ多目标优化的LID布局研究

科学的海绵城市设计方案能够在一定程度上缓解由极端暴雨引发的城市内涝。以北京市海淀区老旧小区为研究对象,将雨洪管理模型(SWMM)与非支配排序遗传算法(NSGA-Ⅱ)相结合,以建设成本费用、总径流削减率以及节点超载时间为优化目标,以各项低影响开发措施(LID)按比例布置的最大面积为约束条件,迭代筛选出Pareto最优曲线,通过分析不同LID措施组合在老旧小区中的雨水排放效率,提出有效的规划建议。研究结果表明:对于单项LID的布置方案,同比例下透水铺装的径流控制效果优于绿色屋顶;LID组合的径流控制效果与建设成本呈正相关,但总径流削减率增长幅度有限,高成本的建设方案并不能达到更优的削减效果,节点超载时间不会持续下降;降雨重现期为10 a时(P=10),该小区LID布局最佳组合为37.12%绿色屋顶+17.7%下沉式绿地+7组雨水罐+9.47%透水铺装。在强降雨条件下耦合SWMM与NSGA-Ⅱ智能算法的多目标优化模型能够为类似社区LID布局设计提供参考。

基于ELID磨削技术的陶瓷材料精密磨削加工技术优化

为解决陶瓷材料的精密磨削加工容易产生裂纹、材料不耐高温的问题,提出基于ELID磨削技术的陶瓷材料精密磨削加工技术优化方法,基于强塑性变形受力的原理,通过公式计算优化陶瓷材料破坏性控制,通过改变磨削深度优化陶瓷材料破坏性控制。使用3种方法进行对比实验,结果表明基于ELID磨削技术样品的磨削表面粗糙度小于3.2 nm,属于加工痕迹不可见范围,优于传统的高速磨削和预应力磨削。

Modulation of p75 neurotrophin receptor mitigates brain damage following ischemic stroke in mice

Stroke is a significant leading cause of death and disability in the United States(Tsao et al.,2022).Approximately 87% of strokes fall into the ischemic category,mainly caused by arterial blockage(Jayaraj et al.,2019).Although the only FDA-approved effective medication is tissue plasminogen activator(tPA),it should be administrated within 4.5 hours of ischemic stroke.Furthermore,tPA has been an integral part of managing acute ischemic stro ke.

传统理水智慧对海绵城市建设的启示与运用--以朗清园居住区LID系统设计为例

对我国造园专著《园冶》中的理水手法进行研究,总结出“疏源之去由,察水之来历”的理水智慧,分析调查现实案例颐和园的水系统情况,论述这一理水智慧的有效性与指导意义。将其运用到新建居住区朗清园LID系统规划设计中,结合现代技术与经验,构建以传统理水手法为基础,科学完整的住区LID系统。

Enhanced structural damage behavior of liquid-filled tank by reactive material projectile impact

A series of ballistic experiments were performed to investigate the damage behavior of high velocity reactive material projectiles(RMPs) impacting liquid-filled tanks,and the corresponding hydrodynamic ram(HRAM) was studied in detail.PTFE/Al/W RMPs with steel-like and aluminum-like densities were prepared by a pressing/sintering process.The projectiles impacted a liquid-filled steel tank with front aluminum panel at approximately 1250 m/s.The corresponding cavity evolution characteristics and HRAM pressure were recorded by high-speed camera and pressure acquisition system,and further compared to those of steel and aluminum projectiles.Significantly different from the conical cavity formed by the inert metal projectile,the cavity formed by the RMP appeared as an ellipsoid with a conical front.The RMPs were demonstrated to enhance the radial growth velocity of cavity,the global HRAM pressure amplitude and the front panel damage,indicating the enhanced HRAM and structural damage behavior.Furthermore,combining the impact-induced fragmentation and deflagration characteristics,the cavity evolution of RMPs under the combined effect of kinetic energy impact and chemical energy release was analyzed.The mechanism of enhanced HRAM pressure induced by the RMPs was further revealed based on the theoretical model of the initial impact wave and the impulse analysis.Finally,the linear correlation between the deformation-thickness ratio and the non-dimensional impulse for the front panel was obtained and analyzed.It was determined that the enhanced near-field impulse induced by the RMPs was the dominant reason for the enhanced structural damage behavior.

A methodology for damage evaluation of underground tunnels subjected to static loading using numerical modeling

We have proposed a methodology to assess the robustness of underground tunnels against potential failure.This involves developing vulnerability functions for various qualities of rock mass and static loading intensities.To account for these variations,we utilized a Monte Carlo Simulation(MCS)technique coupled with the finite difference code FLAC^(3D),to conduct two thousand seven hundred numerical simulations of a horseshoe tunnel located within a rock mass with different geological strength index system(GSIs)and subjected to different states of static loading.To quantify the severity of damage within the rock mass,we selected one stress-based(brittle shear ratio(BSR))and one strain-based failure criterion(plastic damage index(PDI)).Based on these criteria,we then developed fragility curves.Additionally,we used mathematical approximation techniques to produce vulnerability functions that relate the probabilities of various damage states to loading intensities for different quality classes of blocky rock mass.The results indicated that the fragility curves we obtained could accurately depict the evolution of the inner and outer shell damage around the tunnel.Therefore,we have provided engineers with a tool that can predict levels of damages associated with different failure mechanisms based on variations in rock mass quality and in situ stress state.Our method is a numerically developed,multi-variate approach that can aid engineers in making informed decisions about the robustness of underground tunnels.

Damage evolution of rock-encased-backfill structure under stepwise cyclic triaxial loading

Rock-encased-backfill(RB)structures are common in underground mining,for example in the cut-andfill and stoping methods.To understand the effects of cyclic excavation and blasting activities on the damage of these RB structures,a series of triaxial stepwise-increasing-amplitude cyclic loading experiments was conducted with cylindrical RB specimens(rock on outside,backfill on inside)with different volume fractions of rock(VF=0.48,0.61,0.73,and 0.84),confining pressures(0,6,9,and 12 MPa),and cyclic loading rates(200,300,400,and 500 N/s).The damage evolution and meso-crack formation during the cyclic tests were analyzed with results from stress-strain hysteresis loops,acoustic emission events,and post-failure X-ray 3D fracture morphology.The results showed significant differences between cyclic and monotonic loadings of RB specimens,particularly with regard to the generation of shear microcracks,the development of stress memory and strain hardening,and the contact forces and associated friction that develops along the rock-backfill interface.One important finding is that as a function of the number of cycles,the elastic strain increases linearly and the dissipated energy increases exponentially.Also,compared with monotonic loading,the cyclic strain hardening characteristics are more sensitive to rising confining pressures during the initial compaction stage.Another finding is that compared with monotonic loading,more shear microcracks are generated during every reloading stage,but these microcracks tend to be dispersed and lessen the likelihood of large shear fracture formation.The transition from elastic to plastic behavior varies depending on the parameters of each test(confinement,volume fraction,and cyclic rate),and an interesting finding was that the transformation to plastic behavior is significantly lower under the conditions of 0.73 rock volume fraction,400 N/s cyclic loading rate,and 9 MPa confinement.All the findings have important practical implications on the ability of backfill to support underground excavations.

A review of reservoir damage during hydraulic fracturing of deep and ultra-deep reservoirs

Deep and ultra-deep reservoirs have gradually become the primary focus of hydrocarbon exploration as a result of a series of significant discoveries in deep hydrocarbon exploration worldwide.These reservoirs present unique challenges due to their deep burial depth(4500-8882 m),low matrix permeability,complex crustal stress conditions,high temperature and pressure(HTHP,150-200℃,105-155 MPa),coupled with high salinity of formation water.Consequently,the costs associated with their exploitation and development are exceptionally high.In deep and ultra-deep reservoirs,hydraulic fracturing is commonly used to achieve high and stable production.During hydraulic fracturing,a substantial volume of fluid is injected into the reservoir.However,statistical analysis reveals that the flowback rate is typically less than 30%,leaving the majority of the fluid trapped within the reservoir.Therefore,hydraulic fracturing in deep reservoirs not only enhances the reservoir permeability by creating artificial fractures but also damages reservoirs due to the fracturing fluids involved.The challenging“three-high”environment of a deep reservoir,characterized by high temperature,high pressure,and high salinity,exacerbates conventional forms of damage,including water sensitivity,retention of fracturing fluids,rock creep,and proppant breakage.In addition,specific damage mechanisms come into play,such as fracturing fluid decomposition at elevated temperatures and proppant diagenetic reactions at HTHP conditions.Presently,the foremost concern in deep oil and gas development lies in effectively assessing the damage inflicted on these reservoirs by hydraulic fracturing,comprehending the underlying mechanisms,and selecting appropriate solutions.It's noteworthy that the majority of existing studies on reservoir damage primarily focus on conventional reservoirs,with limited attention given to deep reservoirs and a lack of systematic summaries.In light of this,our approach entails initially summarizing the current knowledge pertaining to the types of fracturing fluids employed in deep and ultra-deep reservoirs.Subsequently,we delve into a systematic examination of the damage processes and mechanisms caused by fracturing fluids within the context of hydraulic fracturing in deep reservoirs,taking into account the unique reservoir characteristics of high temperature,high pressure,and high in-situ stress.In addition,we provide an overview of research progress related to high-temperature deep reservoir fracturing fluid and the damage of aqueous fracturing fluids to rock matrix,both artificial and natural fractures,and sand-packed fractures.We conclude by offering a summary of current research advancements and future directions,which hold significant potential for facilitating the efficient development of deep oil and gas reservoirs while effectively mitigating reservoir damage.

Intelligent Risk-Identification Algorithm with Vision and 3D LiDAR Patterns at Damaged Buildings

Existingfirefighting robots are focused on simple storage orfire sup-pression outside buildings rather than detection or recognition.Utilizing a large number of robots using expensive equipment is challenging.This study aims to increase the efficiency of search and rescue operations and the safety offirefigh-ters by detecting and identifying the disaster site by recognizing collapsed areas,obstacles,and rescuers on-site.A fusion algorithm combining a camera and three-dimension light detection and ranging(3D LiDAR)is proposed to detect and loca-lize the interiors of disaster sites.The algorithm detects obstacles by analyzingfloor segmentation and edge patterns using a mask regional convolutional neural network(mask R-CNN)features model based on the visual data collected from a parallelly connected camera and 3D LiDAR.People as objects are detected using you only look once version 4(YOLOv4)in the image data to localize persons requiring rescue.The point cloud data based on 3D LiDAR cluster the objects using the density-based spatial clustering of applications with noise(DBSCAN)clustering algorithm and estimate the distance to the actual object using the center point of the clustering result.The proposed artificial intelligence(AI)algorithm was verified based on individual sensors using a sensor-mounted robot in an actual building to detectfloor surfaces,atypical obstacles,and persons requiring rescue.Accordingly,the fused AI algorithm was comparatively verified.

基于InfoWorks ICM模型的城市小区LID组合方案成本效益研究

针对低影响开发(LID)雨水系统建设中存在成本与效益难以平衡的问题,选取甘肃省天水市某居住小区为研究对象,构建InfoWorks ICM一、二维耦合模型,以不同LID组合方案在不同降雨重现期下的径流总量控制率、径流峰值削减率、积水面积削减率、积水量削减率、固体悬浮物(SS)削减率、化学需氧量(COD)削减率为效益表征量,结合LID设施的生命周期成本定量分析成本效益。结果表明:包含绿色屋顶的LID组合方案成本效益偏低,但对于高重现期降雨具有较强的适应能力,更适用于暴雨频发地区;LID组合方案对于积水面积削减率与积水量削减率的成本效益较高,能有效缓解内涝积水,对于COD削减率的成本效益较低,需进一步优化;雨水桶+生物滞留设施+透水铺装作为总成本效益最高的方案,更适用于研究区域LID雨水系统的建设。研究成果对LID雨水系统的优化设计具有重要参考意义。

Stress-corrosion coupled damage localization induced by secondary phases in bio-degradable Mg alloys:phase-field modeling

In this study,a phase-field scheme that rigorously obeys conservation laws and irreversible thermodynamics is developed for modeling stress-corrosion coupled damage(SCCD).The coupling constitutive relationships of the deformation,phase-field damage,mass transfer,and electrostatic field are derived from the entropy inequality.The SCCD localization induced by secondary phases in Mg is numerically simulated using the implicit iterative algorithm of the self-defined finite elements.The quantitative evaluation of the SCCD of a C-ring is in good agreement with the experimental results.To capture the damage localization,a micro-galvanic corrosion domain is defined,and the buffering effect on charge migration is explored.Three cases are investigated to reveal the effect of localization on corrosion acceleration and provide guidance for the design for resistance to SCCD at the crystal scale.

YOLO-Based Damage Detection with StyleGAN3 Data Augmentation for Parcel Information-Recognition System

Damage to parcels reduces customer satisfactionwith delivery services and increases return-logistics costs.This can be prevented by detecting and addressing the damage before the parcels reach the customer.Consequently,various studies have been conducted on deep learning techniques related to the detection of parcel damage.This study proposes a deep learning-based damage detectionmethod for various types of parcels.Themethod is intended to be part of a parcel information-recognition systemthat identifies the volume and shipping information of parcels,and determines whether they are damaged;this method is intended for use in the actual parcel-transportation process.For this purpose,1)the study acquired image data in an environment simulating the actual parcel-transportation process,and 2)the training dataset was expanded based on StyleGAN3 with adaptive discriminator augmentation.Additionally,3)a preliminary distinction was made between the appearance of parcels and their damage status to enhance the performance of the parcel damage detection model and analyze the causes of parcel damage.Finally,using the dataset constructed based on the proposed method,a damage type detection model was trained,and its mean average precision was confirmed.This model can improve customer satisfaction and reduce return costs for parcel delivery companies.