Simulation of dilatancy-controlled gas migration processes in saturated bentonite using a coupled multiphase flow and elastoplastic H2 M model

Dilatancy-controlled gas flow in preferential pathways plays a key role in the safety analysis of radioactive waste repositories.This is particularly the case for bentonite,an often-preferred barrier material.Gas flow in preferential pathways is characterized by localization and spontaneous behavior,which is challenging to simulate in numerical models due to strong hydro-mechanical coupling.To analyze a laboratory experiment in the framework of the DECOVALEX-2023 project,this study introduced a new approach of combining continuous modelling methods with spatial material properties derived from material heterogeneities and experimental observations.The proposed model utilized hydro-mechanical spatial distributions,namely Young’s modulus and gas entry pressure,and elastoplasticity combined with a linear swelling model.A conceptual strain-dependent permeability approach simulated dilatancycontrolled gas flow based on hydro-mechanical coupling.To test the effectiveness of the presented approach,a gas injection test in a compacted,saturated bentonite sample was simulated using the opensource code OpenGeoSys 5.8 and compared with experimental observations.The presented methodology is capable of simulating localized gas flow in preferential pathways.The spatial distributions of Young’s modulus and gas entry pressure affect the swelling pressure,relative permeability and,in combination with the strain-dependent permeability model,also the intrinsic permeability.

基于多源资料的积层混合云降水微物理特征

基于地基云雷达、微雨雷达和天气雷达等遥测设备观测资料,结合挂载KPR云雷达和DMT粒子测量系统的飞机平台,详细分析了山东积层混合云降水过程的云降水微物理结构特征。结果表明,积层混合云降水过程呈现层状云和对流云降水特征。零度层以上,5~6 km高度层内,对流云降水多普勒速度和谱宽均大于层状云,说明对流云降水环境垂直气流、粒子尺度等均大于层状云。对流云降水,云雷达和微雨雷达时空剖面上出现由衰减造成的“V”字形缺口,云雷达衰减程度大于微雨雷达,且随高度增加,衰减越大。层状云降水,零度层亮带附近,雷达反射率因子跃增高度比多普勒速度高80 m,多普勒速度跃增高度又比谱宽高20 m。降水云系零度层附近降水机制复杂,粒子形态有辐枝冰晶聚合物、针状冰晶聚合物和云滴;0°C层以上,5~6 km处,对流云降水的多普勒速度和谱宽均大于层状云降水,即对流云降水环境垂直气流、粒子尺度范围等均大于层状云降水。

Detrital-zircon geochronology of the Jurassic coal-bearing strata in the western Ordos Basin, North China: Evidences for multi-cycle sedimentation

The western Ordos Basin(WOB), situated in a tectonic transition zone in the North China Craton, acts as an excellent example for studying the Mesozoic intraplate sedimentation and deformation in Asia. In this study, U-Pb ages for 1203 detrital zircons of 14 sandstone samples collected from 11 sections are presented to unravel the sediment source locations and paleogeographic environments of the Early-Middle Jurassic coal-bearing Yan'an Formation in the WOB. Data show that there are five prominent age groups in the detrital zircons of the Yan'an Formation, peaking at ca. 282 Ma, 426 Ma, 924 Ma, 1847 Ma, and2468 Ma. Samples from the northern, middle, and southern parts of the WOB contain these five age categories in various proportions. In the northern region, the Yan'an Formation exclusively contains Early Permian detrital zircons with a single age group peaking at 282 Ma, matching well with the crystallizing ages of the widespread Early Permian granites in the Yinshan Belt to the north and the Alxa Block to the northwest. While in the southern region, the Yan'an Formation mainly contains three groups of detrital zircons, with age peaks at 213 Ma, 426 Ma, and 924 Ma. These zircon ages resemble those of the igneous rocks in the Qilian-Qinling Orogenic Belt to the south-southwest. Samples in the middle region, characterized by a mixture age spectrum with peaks at 282 Ma, 426 Ma, 924 Ma, 1847 Ma and 2468 Ma, are previously thought to have mixed derivations from surrounding ranges. However, by referring to the detrital-zircon age compositions of the pre-Jurassic sedimentary successions and combining with paleontological and petrographic analysis, we firstly propose that the sediments of the Yan'an Formation in the middle region were partly recycled from the Triassic and Paleozoic sedimentary strata in the WOB.The occurrence of recycled sedimentation suggests that the Late Triassic-Early Jurassic intraplate compressional deformation was very intense in the WOB, especially for regions in front of the Qilian Orogenic Belt.

Constraint-induced movement therapy promotes brain functional reorganization in stroke patients with hemiplegia

Stroke patients with hemiplegia exhibit flexor spasms in the upper limb and extensor spasms in the lower limb, and their movement patterns vary greatly. Constraint-induced movement therapy is an upper limb rehabilitation technique used in stroke patients with hemiplegia; however, studies of lower extremity rehabilitation are scarce. In this study, stroke patients with lower limb hemiplegia underwent conventional Bobath therapy for 4 weeks as baseline treatment, followed by constraint-induced movement therapy for an additional 4 weeks. The 10-m maximum walking speed and Berg balance scale scores significantly improved following treatment, and lower extremity motor function also improved. The results of functional MRI showed that constraint-induced movement therapy alleviates the reduction in cerebral functional activation in patients, which indicates activation of functional brain regions and a significant increase in cerebral blood perfusJon. These results demonstrate that constraint-induced movement therapy promotes brain functional reorganization in stroke patients with lower limb hemiplegia.

Rainfall Microphysical Properties of Landfalling Typhoon Yagi(201814)Based on the Observations of Micro Rain Radar and Cloud Radar in Shandong,China

The development and evolution of precipitation microphysical parameters and the vertical structure characteristics associated with Typhoon Yagi(201814)are analyzed in the city of Jinan,Shandong Province based primarily on the observations of a micro rain radar(MRR),a cloud radar,and a disdrometer.The precipitation process is further subdivided into four types:convective,stratiform,mixed,and light precipitation according to the ground disdrometer data,which is in agreement with the vertical profile of the radar reflectivity detected by the MRR.Vertical winds may be the main source of MRR retrieval error during convective precipitation.Convective precipitation has the shortest duration but makes the largest contribution to the cumulative precipitation.Collision-coalescence is the main microphysical process of stratiform precipitation and light precipitation below the bright band observed by the MRR.It is worth noting that as Typhoon Yagi(201814)transformed into an extratropical cyclone,its raindrop size distributions no longer had the characteristics of maritime precipitation,but become more typical of the characteristic of continental precipitation,which represents a very different raindrop size distribution from that which is normally observed in a landfalling typhoon.

Radiotherapy combined with nimotuzumab for elderly esophageal cancer patients:A phaseⅡclinical trial

Objective:To investigate the safety and efficacy of nimotuzumab combined with radiotherapy for elderly patients with non-resectable esophageal carcinoma(EC).Methods:Eligible patients were aged 70 years or older and had treatment-naive,histologically proven inoperable locally advanced EC.Enrolled patients received radiotherapy with a total dose of 50-60 Gy in 25-30 fractions,concurrent with weekly infusion of nimotuzumab.The primary end point was the rate of more than grade 3 toxicities.Results:From June 2011 to July 2016,46 patients with stageⅡ-IV EC with a median age of 76.5 years were enrolled.There were 10,28 and 8 patients with stageⅡ,III and IV disease,respectively.The common acute toxicities included esophagitis(grade 1-2,75.4%;grade 3,8.7%),pneumonitis(grade 1,4.3%;grade 2,6.5%;grade3,2.2%),leukopenia(grade 1-2,60.9%;grade 3-4,4.4%),gastrointestinal reaction(grade 1-2,17.3%;grade 3,2.2%),thrombocytopenia(grade 1-2,21.7%;grade 3,2.2%),and radiothermitis(grade 1-2,39.2%).The incidence of grade 3-4 adverse effects was 17.4%.No grade 5 toxicities were observed.Clinical complete response,partial response,stable disease,and progressive disease were observed in 1(2.2%),31(67.4%),12(26.1%),and 2(4.3%)patients,respectively.The median overall survival(OS)and progression-free survival(PFS)were 17 and 10 months,respectively.The 2-,3-,and 5-year OS and PFS rates were 30.4%,21.7%,19.6%,and 26.1%,19.6%,19.6%,respectively.Conclusions:Nimotuzumab combined with radiotherapy is a safe and effective therapy for elderly patients who are not surgical candidates.Further studies are warranted to confirm its therapeutic effects in elderly EC patients.

Regional cerebral blood flow imaging assessment of brain function reconstruction in elderly hemiplegia patients by body weight support treadmill training

The mechanism underlying body weight support treadmill training in elderly hemiplegic stroke patients is largely unknown. This study aimed to elucidate the changes of cortical blood flow in seven elderly patients with post-stroke hemiplegia before and after body weight support treadmill training by semi-quantitative analysis of regional cerebral blood flow assessed by single photon emission computed tomography. Body weight support treadmill training for 6 months was effective in improving cerebral blood flow and promoting the walking speed and balance recovery in elderly patients with post-stroke hemiplegia.

Study on preparation of fast curing novolaks for the shell process

To save energy and raise molding and coremaking productivity, the synthetic procedure of novolaks for the shell process was investigated. The study indicated that it was difficult to obtain fast curing novolaks under strongly acidic conditions alone. A novel synthetic procedure was proposed for preparing novolaks in a two-step manner, a divalent metal salt catalyzed novolak preparation followed by a strong acid catalyzed novolak preparation. The optimum conditions for the two-step procedure were determined by orthogonal experiment design. The results showed that it was easy to prepare fast curing novolaks with cure time in the range of 20 s to 30 s and softening point in the range of 80℃ to 90℃ under complex catalysis conditions.

THE EXISTENCE AND NON-EXISTENCE OF SIGN-CHANGING SOLUTIONS TO BI-HARMONIC EQUATIONS WITH A p-LAPLACIAN

We investigate the bi-harmonic problem{Δ^(2)u-α▽·(f(▽u))-βΔ_(p)u=g(x,u) in Ω,δu/δn=0,δ(Δu)/δn=0 on δΩ,where Δ^(2)u=Δ(Δu),Δ_(p)u=div(|▽u|^(p-2)▽u)with p>2.Ω is a bounded smooth domain in R^(N),N≥1.By using a special function space with the constraint ∫_(Ω)udx=0,under suitable assumptions on f and g(x,u),we show the existence and multiplicity of sign-changing solutions to the above problem via the Mountain pass theorem and the Fountain theorem.Recent results from the literature are extended.

Hydro-mechanical fault reactivation modeling based on elasto-plasticity with embedded weakness planes

In this paper,an elasto-plastic constitutive model is employed to capture the shear failure that may occur in a rock mass presenting mechanical discontinuities,such as faults,fractures,bedding planes or other planar weak structures.The failure may occur in two modes:a sliding failure on the weak plane or an intrinsic failure of the rock mass.The rock matrix is expected to behave elastically or fail in a brittle manner,being represented by a non-associated Mohr-Coulomb behavior,while the sliding failure is represented by the evaluation of the Coulomb criterion on an explicitly defined plane.Failure may furthermore affect the hydraulic properties of the rock mass:the shearing of the weakness plane may create a transmissive fluid pathway.Verification of the mechanical submodel is conducted by comparison with an analytical solution,while the coupled hydro-mechanical behavior is validated with field data and will be applied within a model and code validation initiative.The work presented here aims at documenting the progress in code development,while accurate match of the field data with the numerical results is current work in progress.

Controllable assembling of highly-doped linked carbon bubbles on graphene microfolds

Carbon-based microassemblies(CMs) have attracted significant attention in numerous applications due to their unique hierarchical structures and delicate building blocks,especially when hollow carbon spheres(HCSs) are reasonably introduced into the construction.Herein,a new design for novel HCSscombined CMs is proposed.Remarkably,the HCSs are linear carbon bubbles linked one-by-one, arranging into necklaces decorating on the graphene microfolds.Detailed thermal analysis confirm that high temperatures straighten the linked carbon bubbles into bamboo-like carbon nanofibers,evidently due to the attenuation of doping degree.Benefiting from the abundant active sites of carbon bubbles,the obtained CMs exhibit satisfactory electrocatalytic activity for oxygen reduction reactions.This work establishes a bridge to precisely control the synthesis of carbon-based hierarchical architectures.

Analysis and Application of Hydropower Real-time Performance Calculation

The hydropower running and performance can be displayed and analyzed by the real-time remote system. Real-time performance data of the hydraulic turbine unit can be obtained through the analysis of real-time operating data of the hydraulic turbine unit. It can not only guide significance for long-term operation of hydraulic turbine unit, but also provide a reference for improving the Hydropower hydro efficiency, economic dispatch of hydraulic turbine unit and performance comparison before and after the overhaul.

Cover Figure

Body weight support treadmill training for 6 months was effective in improving cerebral blood flow and promoting the walking speed and balance recovery in elderly patients with post-stroke hemiplegia.

Numerical analysis of thermal impact on hydro-mechanical properties of clay

As is known, high-level radioactive waste （HLW） is commonly heat-emitting. Heat output from HLWwilldissipate through the surrounding rocks and induce complex thermo-hydro-mechanical-chemical（THMC） processes. In highly consolidated clayey rocks, thermal effects are particularly significantbecause of their very low permeability and water-saturated state. Thermal impact on the integrity of thegeological barriers is of most importance with regard to the long-term safety of repositories. This studyfocuses on numerical analysis of thermal effects on hydro-mechanical properties of clayey rock using acoupled thermo-mechanical multiphase flow （TH2M） model which is implemented in the finite elementprogramme OpenGeoSys （OGS）. The material properties of the numerical model are characterised by atransversal isotropic elastic model based on Hooke＇s law, a non-isothermal multiphase flow model basedon van Genuchten function and Darcy＇s law, and a transversal isotropic heat transport model based onFourier＇s law. In the numerical approaches, special attention has been paid to the thermal expansion ofthree different phases： gas, fluid and solid, which could induce changes in pore pressure and porosity.Furthermore, the strong swelling and shrinkage behaviours of clayey material are also considered in thepresent model. The model has been applied to simulate a laboratory heating experiment on claystone.The numerical model gives a satisfactory representation of the observed material behaviour in thelaboratory experiment. The comparison of the calculated results with the laboratory findings verifies thatthe simulation with the present numerical model could provide a deeper understanding of the observedeffects. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.

Accuracy controlling and mechanical behaviors of precursor-derived ceramic SiOC microlattices by projection micro stereolithography(PμSL)3D printing

Precursor-derived ceramic SiOC(PDC-SiOC)microlattices exhibit excellent oxidation resistance,high-temperature stability,and superior mechanical properties.However,the printing accuracy of the PDC-SiOC microlattices by 3D printing is still limited,and mechanical properties of the PDC-SiOC microlattices have not been studied systematically.Here,PDC-SiOC octet microlattices were fabricated by projection micro stereolithography(PμSL)3D printing,and photoabsorber(Sudan III)’s effect on the accuracy was systematically analyzed.The results showed that the addition of Sudan III improved the printing accuracy significantly.Then,the ceramization process of the green body was analyzed in detail.The order of the green body decreased,and most of their chemical bonds were broken during pyrolysis.After that,the PDC-SiOC microlattices with different truss diameters in the range of 52–220μm were fabricated,and their mechanical properties were investigated.The PDC-SiOC microlattices with a truss diameter of 52μm exhibited higher compression strength(31 MPa)than those with bigger truss diameters.The size effect among the PDC-SiOC microlattices was analyzed.Our work provides a deeper insight into the manufacturing of PDC-SiOC micro-scaled architectures by 3D printing and paves a path to the research of the size effect in ceramic structures.

大数据技术对税收风险管理的影响与国际借鉴

随着现代信息技术在税收领域的广泛应用,以及我国税收征管改革的不断深入,大数据技术已经渗透到了税收管理的方方面面。本文针对税收风险管理中存在的数据分析质量欠佳、分析精准度欠缺、管理人员知识老化等问题,在充分借鉴世界各国先进经验的基础上,探索加强税收风险管理,并提出相关的对策与建议。

“一带一路”沿线国家税收制度改革对我国的启示——以印度尼西亚、印度、俄罗斯为例

随着"一带一路"倡议的不断深入,中国"走出去"企业在沿线国家的投资与发展增长迅速,同时也面临着与投资国之间税收制度差异及衔接不畅的问题。从沿线国家及企业经济利益自我保护的角度考虑,被投资国的税收制度特别是企业所得税对中国企业的投资回报产生了一定的影响,进而成为跨境企业税收争议的重要原因。因此,通过跨境税收协定及双边磋商,解决国内企业税收损失和避免双重征税的问题非常关键。

出口骗税屡查不止的深层原因及对策研究

出口货物以不含税价格进入国际市场,公平参与贸易竞争是国际通行的做法。出口退税制度自1985年实行以来,对促进外贸经济发展,推动"一带一路"、供给侧改革、财税体制改革及营改增顺利实施发挥了积极作用。然而,受金钱的驱使与引诱,部分国内外不法分子将出口退税作为谋取非法利益的工具,在当前全国重拳打击出口骗税的形势下,涉税案件仍然频发不断、屡查不止。对此,本文通过对出口退税政策制度、职能管理、部门协作、风险防控等方面的研究,分析和挖掘出口骗税的深层原因,按照国家税务总局"体制打骗、机制打骗、方法打骗"的指示精神,提出相应的对策建议。

共享经济下税收管理相关对策建议

近年来,随着移动互联、移动支付等新技术的出现,共享经济发展迅速,人们的出行、餐饮、知识、技能、物流等共享成分包罗万象,各种新经济形态下的互通方式不断涌现。而税收管理中仅靠获取局部数据寻求彼此的因果关系,已经无法适应和满足当前共享经济发展的需要。本文从分析税收管理存在的问题入手,借鉴国际经验,提出共享经济模式下加强税收管理以及风险防控的对策及建议。

加强与周边发展中国家税务合作的思考——基于“亲诚惠容”理念与“一带一路”倡议

在习近平总书记提出的"亲诚惠容"周边外交理念与"一带一路"倡议指引下,中国与周边发展中国家的经济合作成果丰硕,国际税收合作日益加深。为了进一步帮助周边发展中国家提高税收征管能力,建议大力支持具备地缘优势的沿边省份在发展边境贸易合作基础上,搭建国际经贸合作区纳税服务综合平台,提升税收征管能力和税收情报交换能力,探索建立"四个体系",扎实开展与周边发展中国家的税务合作。