Monolithic Convex Limiting for Legendre-Gauss-Lobatto Discontinuous Galerkin Spectral-Element Methods

We extend the monolithic convex limiting(MCL)methodology to nodal discontinuous Galerkin spectral-element methods(DGSEMS).The use of Legendre-Gauss-Lobatto(LGL)quadrature endows collocated DGSEM space discretizations of nonlinear hyperbolic problems with properties that greatly simplify the design of invariant domain-preserving high-resolution schemes.Compared to many other continuous and discontinuous Galerkin method variants,a particular advantage of the LGL spectral operator is the availability of a natural decomposition into a compatible subcellflux discretization.Representing a highorder spatial semi-discretization in terms of intermediate states,we performflux limiting in a manner that keeps these states and the results of Runge-Kutta stages in convex invariant domains.In addition,local bounds may be imposed on scalar quantities of interest.In contrast to limiting approaches based on predictor-corrector algorithms,our MCL procedure for LGL-DGSEM yields nonlinearflux approximations that are independent of the time-step size and can be further modified to enforce entropy stability.To demonstrate the robustness of MCL/DGSEM schemes for the compressible Euler equations,we run simulations for challenging setups featuring strong shocks,steep density gradients,and vortex dominatedflows.

High-Order DG Schemes with Subcell Limiting Strategies for Simulations of Shocks,Vortices and Sound Waves in Materials Science Problems

Shock waves,characterized by abrupt changes in pressure,temperature,and density,play a significant role in various materials science processes involving fluids.These high-energy phenomena are utilized across multiple fields and applications to achieve unique material properties and facilitate advanced manufacturing techniques.Accurate simulations of these phenomena require numerical schemes that can represent shock waves without spurious oscillations and simultaneously capture acoustic waves for a wide range of wavelength scales.This work suggests a high-order discontinuous Galerkin(DG)method with a finite volume(FV)subcell limiting strategies to achieve better subcell resolution and lower numerical diffusion properties.By switching to the FV discretization on an embedded sub-cell grid,the method displays advantages with respect to both DG accuracy and FV shock-capturing ability.The FV scheme utilizes a class of high-fidelity schemes that are built upon the boundary variation diminishing(BVD)reconstruction paradigm.The method is therefore able to resolve discontinuities and multi-scale structures on the subcell level,while preserving the favorable properties of the high-order DG scheme.We have tested the present DG method up to the 6th-order accuracy for both smooth and discontinuous noise problems.

Internal limiting membrane peeling combined with silicone oil or air tamponade for highly myopic foveoschisis

AIM:To compare the efficacy of pars plana vitrectomy(PPV)combined with internal limiting membrane(ILM)and silicone oil or sterile air tamponade for the treatment of myopic foveoschisis(MF)in highly myopic eyes.METHODS:This retrospective study included 48 myopic eyes of 40 patients with MF and axial lengths(ALs)ranging from 26-32 mm treated between January 2020 and January 2022.All patients were underwent PPV combined with ILM peeling followed by sterile air or silicone oil tamponade and followed up at least 12mo.Based on the features on spectral-domain optical coherence tomography(SD-OCT),the eyes were divided into the MF-only group(Group A,n=15 eyes),MF with central foveal detachment group(Group B,n=20 eyes),and MF with lamellar macular hole group(Group C,n=13 eyes).According to AL,eyes were further divided into three groups:Group D(26.01-28.00 mm,n=12 eyes),Group E(28.01-30.00 mm,n=26 eyes),and Group F(30.01-32.00 mm,n=10 eyes).The best-corrected visual acuity(BCVA),central foveal thickness(CFT),and complications were recorded.RESULTS:The patients included 16 males and 24 females with the mean age of 56±9.82y.The BCVA and CFT improved in all groups after surgery(P<0.01),while there was no significant difference of the CFT in Group A,B,and C postoperatively(P>0.05).The intergroup differences of BCVA and CFT postoperatively were statistically significant in Group D,E,and F.Twenty eyes were injected with sterile air,and 28 eyes were injected with silicone oil for tamponade based on the AL.However,there was no statistically significant difference among Groups D,E,and F in terms of the results of sterile air or silicone oil tamponade.The mean recovery time was 5.9mo for MF patients subjected to silicone oil tamponade and 7.7mo for patients subjected to sterile air tamponade,and the difference was not statistically significant.CONCLUSION:PPV and ILM peeling combined with silicone oil or sterile air tamponade can achieve good results for MF in highly myopic eyes with ALs≤32 mm.

Effects of vitrectomy combined with internal limiting membrane peeling in patients with diabetic macular edema

BACKGROUND Diabetic macular edema(DME),a chronic microvascular complication of diabetes,is a leading cause of visual impairment and blindness.Pars plana vitrectomy(PPV)can restore the normal macular structure and reduce macular edema,whereas internal limiting membrane(ILM)peeling is used to treat tractional macular diseases.Despite the advantages,there is limited research on the combined effects of PPV with ILM peeling.AIM To observe the effects of PPV combined with ILM peeling on postoperative central macular thickness(CMT),best-corrected visual acuity(BCVA),cystoid macular edema(CME)volume,and complications in patients with DME.METHODS Eighty-one patients(92 eyes)diagnosed with DME at the Beijing Shanqu Liangxiang Hospital between January and December 2022 were randomly divided to undergo PPV alone(control group:41 patients,47 eyes)or PPV+ILM peeling(stripping group:40 patients,45 eyes);a single surgeon performed all surgeries.The two groups were compared preoperatively and 1 and 3 months postoperatively.RESULTS Preoperatively,both groups had comparable values of CMT,BCVA,and CME volume(P>0.05).After surgery(both 1 and 3 months),both groups showed significant reductions in CMT,BCVA,and CME volume compared to preoperative levels,with the stripping group showing more significant reductions compared to the control group(P<0.05).Further repeated-measures ANOVA analysis for within-group differences revealed significant effects of group and time,and interaction effects for CMT,BCVA,and CME volume(P<0.05).There were no significant differences in the incidence of complications between the groups(retinal detachment:control=2,stripping=1;endophthalmitis:Control=4,stripping=1;no cases of secondary glaucoma or macular holes;χ^(2)=0.296,P=0.587).CONCLUSION PPV with ILM peeling can significantly improve the visual acuity of patients with DME,reduce CMT,and improve CME with fewer complications.

Travel-Limiting Disabilities in the United States: Why Accessibility Matters?

This study evaluates the distribution of travel-limiting disabilities across genders and geographic locations in the United States. This study aims to describe and compare the socioeconomic and demographic variables of the people with and without travel-limiting disabilities across geographic locations and gender. The study further evaluates the trip purpose and impact of Covid-19 fourth wave pandemic on the use of public transit and travel to physical workplace for the people with and without travel-limiting disabilities across gender and geographic locations. The study uses the 2022 weighted National Household Travel Survey dataset and employs descriptive statistics. Results reaffirm the findings from previous literature that there are more people with travel-limiting disabilities in urban areas and among women. Over 50 percent of people aged 65 and above have a form of travel-limiting disabilities. The most trip for people with travel-limiting disabilities is made for shopping and medical purposes. Across all categories, rural areas, urban areas, male and female for the people without travel-limiting disabilities, COVID-19 fourth wave did not change the pattern of trips made to physical workplace as pre-COVID-19 era. This pattern is also observable for the people with travel-limiting disabilities in rural and urban areas. Females with travel-limiting disabilities reported making less trips to physical workplaces while male reported doing the same as before COVID-19 era. The study concludes that the quantification of travel-limiting disabilities across geographic location and gender is vital in disability study and could drive policy implementation for improved accessibility for the vulnerable population.

Limiting Magnitudes of the Wide Field Survey Telescope(WFST)

Expected to be of the highest survey power telescope in the northern hemisphere,the Wide Field Survey Telescope(WFST)will begin its routine observations of the northern sky since 2023.WFST will produce a lot of scientific data to support the researches of time-domain astronomy,asteroids and the solar system,galaxy formation and cosmology and so on.We estimated that the 5σlimiting magnitudes of WFST with 30 s exposure are u=22.31mag,g=23.42 mag,r=22.95 mag,i=22.43 mag,z=21.50 mag,w=23.61 mag.The above values are calculated for the conditions of airmass=1.2,seeing=075,precipitable water vapor=2.5 mm and Moon-object separation=45°at the darkest New Moon night of the Lenghu site(V=22.30 mag,Moon phaseθ=0°).The limiting magnitudes in different Moon phase conditions are also calculated.The calculations are based on the empirical transmittance data of WFST optics,the vendor provided CCD quantum efficiency,the atmospherical model transmittance and spectrum of the site.In the absence of measurement data such as sky transmittance and spectrum,we use model data.

How internal limiting membrane peeling revolutionized macular surgery in the last three decades

INTRODUCTION The Italian anatomist Filippo Pacini discovered the internal limiting membrane(ILM) in 1844[1]. The ILM is the basement membrane of the retinal Müller cells representing the structural interface between the retina and the vitreous. The macular ILM is thickest, measuring 2.5 μm and progressively thins to 0.5 μm at the vitreous base[2].

Perspective: Limiting Antimicrobial Resistance with Artificial Intelligence/Machine Learning

The author traces his experience with the application of computers in clinical microbiology over the past 60 years,specifically in directing clinicians to treat bacterial infections diagnosed by the laboratory and the antibacterial agent(s)that could be used to treat those infections.Appropriate use of antibiotics will result in reduced antimicrobial resistance,which is increasing worldwide.An early form of AI,Mycin(1976),a system based on rules provided by experts designed to propose antibiotic regimens for central nervous system infections,was never applied due to the limitations in the number of rules that could be incorporated into the clinical workflow.Machine learning(ML)was developed to overcome the limitations of expert systems.Several variables that influence the outcome bacteria/drug interaction,such as the source of the infection,absence of antimicrobial resistance markers,patients’health profile,and the historical susceptibility within the hospital and the local area are incorporated in the proposed comprehensive AI/ML program.The role of AI in the discovery of new antimicrobial agents is also addressed.

Laser shaping and optical power limiting of pulsed Laguerre–Gaussian laser beams of high-order radial modes in fullerene C60

We study the strong nonlinear optical dynamics of nanosecond pulsed Laguerre–Gaussian laser beams of high-order radial modes with zero orbital angular momentum propagating in the fullerene C60molecular medium. It is found that the spatiotemporal profile of the incident pulsed Laguerre–Gaussian laser beam is strongly reshaped during its propagation in the C60molecular medium. The centrosymmetric temporal profile of the incident pulse gradually evolves into a noncentrosymmetric meniscus shape, and the on-axis pulse duration is clearly depressed. Furthermore, the field intensity is distinctly attenuated due to the field-intensity-dependent reverse saturable absorption, and clear optical power limiting behavior is observed for different orders of the input pulsed Laguerre–Gaussian laser beams before the takeover of the saturation effect;the lower the order of the Laguerre–Gaussian beam, the lower the energy transmittance.

Limiting Factors and Countermeasures for the Development of Biological Herbicides

This paper mainly analyzes the main limiting factors in the development of biological herbicides,such as narrow herbicidal spectrum,vulnerable to environmental impacts,difficulties in preparing dosage forms,difficult separation and low yield of active substances,biological safety,etc.Moreover,countermeasures and suggestions are put forward,including strengthening the study of biological screening of herbicidal activity,microbial metabolites and their use as lead compounds,dosage forms,fungi complex formulation,fungi and herbicide complex formulation,and fermentation technology.

Study on Hydrogen Storage Properties,Anti-Oxide Ability and Rate Limiting Step of ZrCr-Based Alloy after Introducing Cobalt as Additive

In this work,the microstructure,hydrogen storage properties,anti-oxide ability and rate limiting step of Zr(Cr_(1−x)Co_(x))_(2)(x=0,0.2,0.4 and 0.6)alloys have been investigated.After studying the crystal structure,we found that all alloy samples could show C14-type phase but the alloy sample x=0 could also show a small amount of Cr phase.Rietveld fitting showed that lattice parameter and unit cell volume of C14-type phase decreased with increasing x.After further research,it was clear that the first hydrogen absorption capacity decreased with increasing x.But introducing more Co content had a positive influence on the effective hydrogen storage capacity and cyclic hydrogen absorption and desorption properties of the alloy sample.We also found that adding Co to ZrCr_(2)alloy could improve its anti-oxide ability.In addition to this,the rate limiting step model was also studied.

文本分类算法及其应用场景研究综述

随着大数据时代的到来,互联网中的文本信息迎来了井喷式的增长.文本分类作为自然语言处理中最重要的技术之一,其广泛应用于多个领域,如情感分析、新闻分类、自然语言推理、主题标记、抽取式问答、虚假内容检测等.从传统机器学习分类方法理论的深入到深度学习分类方法探索的兴起,相关研究模型与思路也在不断演变,各类新的方法、数据集和评价指标层出不穷,丰富了文本分类领域的研究,取得了卓越的理论成就和应用效果.尽管如此,新技术不断发展和业务应用场景不断丰富,同时,也为文本分类研究带来了许多新的问题与挑战,如数据约束场景中不均衡数据的文本表征学习、小样本场景下的文本分类等.针对当前研究难题与挑战,本文对文本分类方法进行了系统性调研,并对当前方法在实际应用场景中面临的技术挑战和未来的研究方向进行了综合探讨.具体而言,本文主要综述了七部分内容,分别是:(1)对文本分类技术的相关基础知识进行了全面介绍,包括文本分类的常见符号定义、计算范式和文本预处理技术;(2)对基于传统机器学习的文本分类方法进行了详细总结;同时,为了方便读者针对不同的应用场景选择合适的分类模型,本文对不同分类器擅长处理的文本分类难题及方法优劣进行了总结;(3)对基于新兴深度学习的文本分类方法进行了周详梳理,根据领域内代表性技术的核心思想进行分类,在此基础上对不同类别下的主要方法进行描述,同时对其技术的优劣进行了总结;(4)为了方便读者对文本分类模型的有效性进行验证,针对文本分类技术应用最为广泛的七大场景,本文对相关数据集进行了系统性的总结;(5)本文对不同任务目标下的常用的模型评价方法进行详尽介绍,以便对模型性能进行合理的定量评估;(6)基于上述内容,本文对典型应用场景中不同种类文本分类算法进行了性能总结对比;(7)本文分别从数据约束与模型计算两个层面对当前文本分类技术所面临的挑战和未来的重要研究方向进行了总结.本文通过梳理文本分类研究发展脉络,对涉及的代表性技术进行了详细总结和对比分析,有效填补了文本分类领域前沿技术的应用综述空白.

基于极限平衡法的危岩倾覆稳定性三维计算方法

目前危岩防治工作中,危岩稳定性评价主要以简化后的二维剖面作为计算模型。由于自然界中的危岩形态极不规则,采用二维剖面计算模型并不能真实反映危岩受力情况。为了研究危岩稳定性三维计算方法,在前人研究基础上,基于极限平衡理论,提出了由后缘裂缝抗拉强度控制的危岩倾覆稳定性三维计算公式,采用数值积分和空间几何方法给出了在危岩单体三维模型基础上求解危岩后缘岩体抗拉力、水压力及其力矩计算公式和实现流程。以三峡库区瞿塘峡吊嘴危岩为实例开展了应用,并通过数值分析进行了验证。通过不同形态危岩的三维稳定性分析,讨论了三维与二维稳定性计算结果的关系,对比发现危岩形态对稳定性计算结果有明显影响,三维计算较二维计算更准确和实用。

植物生长调节剂在花生中的应用及安全性分析

为明确花生生产中植物生长调节剂的使用情况,通过查询中国农药信息网,统计汇总花生目前有效登记调节剂种类,并查询食品安全国家标准《食品中农药最大残留限量》(GB 2763—2021)中花生中调节剂的最大残留限量和检测方法,分析花生生产中主要使用的调节剂的毒性,为下一步相关标准的制定和修订提出意见和建议,同时也为花生产业的出口创汇及高质量发展提供参考,提升中国花生产业的国际竞争力,保障中国花生产业健康可持续发展。

平台经济领域强化反垄断的正当性与合理限度

近些年来,国内外在平台经济领域开展了声势浩大的反垄断行动,尤其是欧盟出台的《数字市场法》和我国强调“强化反垄断和防止资本无序扩张”备受关注。基于平台经济竞争的鲜明特点和数字平台对经济社会的巨大影响,强化平台经济领域的反垄断有其理论上的正当性和现实的必要性。与此同时,平台经济创新发展的内在要求又决定了在平台经济领域的反垄断有其合理的边界和必要的限度。美国和欧盟等在平台经济领域反垄断上的差异性反映了国际竞争的现实情况,我国需要从国家利益最大化角度出发对平台经济领域反垄断策略做出理性选择,以促进我国平台经济规范健康持续发展。

基于轻型自限制注意力的结构光相位及深度估计混合网络

相位提取与深度估计是结构光三维测量中的重点环节,目前传统方法在结构光相位提取与深度估计方面存在效率不高、结果不够鲁棒等问题。为了提高深度学习结构光的重建效果,本文提出了一种基于轻型自限制注意力(Light Self-Limited-Attention,LSLA)的结构光相位及深度估计混合网络,即构建一种CNN-Transformer的混合模块,并将构建的混合模块放入U型架构中,实现CNN与Transformer的优势互补。将所提出的网络在结构光相位估计和结构光深度估计两个任务上进行实验,并和其他网络进行对比。实验结果表明:相比其他网络,本文所提出的网络在相位估计和深度估计的细节处理上更加精细,在结构光相位估计实验中,精度最高提升31%;在结构光深度估计实验中,精度最高提升26%。该方法提高了深度神经网络在结构光相位估计及深度估计的准确性。

家蚕素斑品种菁松的茶斑限性定向转育

为在家蚕现行素斑品种菁松的幼虫发育早期进行雌雄性别鉴别,实现雌雄分养分缫差异化利用目的,用普斑限性品系云蚕7A的雌与茶斑品系Cb的雄杂交后,再分别与现行素斑品系菁松A、菁松B杂交,其后代连续数次回交素斑亲本后自交,结合分类选择进行个体和蛾区选择淘汰,将云蚕7A的普斑限性基因和Cb的茶斑基因转入现行素斑品种菁松中,定向转育得到菁A茶限和菁B茶限。结果表明:转育过程中,幼虫斑纹分化成颜色与形状易于分辨的茶斑与非茶斑2种类型,转育得到的菁A茶限和菁B茶限幼虫在3龄初期就会呈现茶斑颜色深浅明显不同的分化,能准确分辨雌雄,其虫蛹率分别为96.91%和96.40%,全茧量分别为1.62 g和1.56 g,茧层率分别为23.78%和23.26%,经济性状与其轮回亲本的差异较小,表现出健康好养、茧质优良等特性。研究结果可为创建特殊性状的育种材料、差异化利用雌雄蚕,以及降低雄蚕种繁育成本奠定基础。

石灰石露天矿高陡边坡稳定性计算分析

以西南某石灰石矿高陡边坡为研究对象,根据矿山边坡现状、边坡岩体结构和结构面发育特征因素对“现状边坡”和“终了边坡”进行地质分区,通过岩石室内物理力学试验获得坡体岩石物理力学参数,采用GSI法计算边坡岩体内摩擦角、粘聚力、变形模量和泊松比等参数,评估边坡地质强度特性,采用Morgenstern-Price极限平衡法分三种荷载工况分别计算“现状边坡”和“终了边坡”各分区稳定性系数。经分析,该石灰石矿各地质分区“现状边坡”和“终了边坡”稳定性好,采场边坡参数设计合理,可为矿山扩产安全设施设计和安全生产提供参考。

大学生就业能力培养中高校的“有限责任”

培养大学生就业能力是高等教育的本职所在、应有之义,是高校的主责主业之一,但就业能力培养参与主体多元、影响因素众多,不能任意放大单一主体的责任,亟须在高校、政府、雇主、学生个体等利益相关者之间建立明确的责任分担机制。高校在大学生就业能力培养方面客观存在权力有限性、能力有限性与资源有限性,应针对性进行责任的纵向和横向配置,建立基于时间和基于范畴的有限责任,明确大学生就业能力培养中高校的责任边界,有效区分高校在大学生就业能力培养内容产品提供方面的主导责任、个人与自我方面的引导责任以及服务与机会方面的支持责任。

ChatGPT视域下的知识限度与积极物化:从庄周出发的思考

ChatGPT可以被看成是一个“自本自根”的世界模型。在其内部的神经网络之中,似乎存在一个道家所强调的道。然而,从《庄子·知北游》中的两段经典对话中我们获得的新启示是,ChatGPT所表达的那些可言说的知识未必是真实可靠的知识。同时,使用者与ChatGPT的对话往往会演变为一方对另一方的臣服或对抗,而日常生活中的多人对话往往可以提供一种对结论的开放性。大模型的无限知识同样存在进一步的进化空间。与ChatGPT相比,GPT-4明显知道了自己知识的限度。目前的大模型框架更多是一种普遍性框架,其对问题的回答往往是通用性的解释,而进化的方向恰恰是要增加向量数据库。知识限度的意义就在于要回到多样性本身。人类对大模型的有待使用,最终会产生无待焦虑。换言之,当外在依赖变成内在依赖的时候,人们就会产生无待焦虑。这种无待焦虑最终会演化为后人类焦虑。破除这些焦虑的关键,同样需要在庄周思想中挖掘。这种积极物化的关键是,放低身段,将自己置于一个与物平等的角度,向物学习,格物致知,最终达到物我两忘的真人之境。从庄周丧我的角度可以更加接近物我两忘,其最终可能会帮助人类进入人机和谐相处的两行世界。