Lateral earth pressure of granular backfills on retaining walls with expanded polystyrene geofoam inclusions under limited surcharge loading

Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills(henceforth referred to as EPS-wall),under limited surcharge loading are investigated through two-and three-dimensional model tests.The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading,only an approximately triangular backfill slides in the wall under limited surcharge loading.The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear,and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading.An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading,and its performance was fully validated by the three-dimensional model tests.

Key Factors to Consider When Introducing a New Vaccine in Low-Income Settings: Lessons from Malawi Expanded Program on Immunization

Introduction: As new vaccines become available, countries must assess the relevance to introduce them into their vaccination schedules. Malawi has recently introduced several new vaccines and plans to introduce more. This study was conducted to identify key factors that need to be considered when deciding to introduce a new vaccine and current challenges faced by low and middle income countries using Malawi as an example. Methodology: The study employed a desk review approach, examining published literature from various sources such as PubMed, Medline, and Google Scholar. Policy documents from organizations like the World Health Organization, GAVI the Alliance, and the Ministry of Health for Malawi were also included. A total of 99 articles and documents on new vaccine introduction, challenges of immunization, policy documents in immunization and health systems strengthening were included. The review focused on addressing five key areas critical to new vaccine introduction namely: the need for a vaccine, availability of the vaccine, safety and effectiveness of the vaccine, demand for the vaccine, and the prudent use of public or private funds. Results: Malawi considered the burden of cervical cancer and the significance of malaria in the country when introducing the HPV and malaria vaccines. The country opted for vaccines that can be handled by the cold chain capacity and available human resources. Despite that malaria vaccine and Typhoid Conjugate Vaccine trials were done in country, there are limited vaccine safety and efficacy trials conducted in Malawi, leading to a reliance on WHO-prequalified vaccines. Demand for newly introduced vaccines varied, with high demand for Oral Cholera Vaccine during a cholera outbreak, while demand for COVID-19 vaccines decreased over time. Although cost-effectiveness studies were limited in the country, 2 studies indicated that Typhoid Conjugate Vaccine and malaria vaccine would be cost effective. All these have been implemented despite having challenges like lack of accurate surveillance data, inadequate cold chain capacity, limited safety and efficacy vaccine clinical trials, political influence, and limited funding. Conclusion: Despite several challenges Malawi set a good example of the careful considerations required before introducing a new vaccine. The process involves data review, priority setting, precise planning, and consultation with stakeholders. Low-income countries should invest in vaccine safety, efficacy, and cost-effectiveness trials.

Compression properties of cost-efficient porous expanded clay reinforced AA7075 syntactic foams fabricated by industrial-oriented die casting technology

In today’s manufacturing industries,hard competition between rival firms makes it compulsory for researchers to design lighter and cheaper machine components due to the megatrends of cost-effectiveness and anti-pollution.At this point,aluminum syntactic foams(ASFs)are new-generation engineering composites and come into the upfront as a problem-solver.Owing to their features like low density,sufficient elongation,and perfect energy absorption ability,these advanced foams have been considerably seductive for many industrial sectors nowadays.In this study,an industrial-oriented automatic die casting technology was used for the first time to manufacture the combination of AA7075/porous expanded clay(PEC).Micro evaluations(optical and FESEM)reveal that there is a homogenous particle distribution in the foam samples,and inspections are compatible with the other ASF studies.Additionally,T6 aging heat treatment was operated on one half of the produced foams to explore the probable impact of aging on the compressive responses.Attained results show that PEC particles can be an alternative to expensive hollow spheres used in the previous works.Besides,a favorable relationship is ascertained between the aging treatment and mechanical properties such as compression strength and plateau strength.

Optimization of Channel Structure of Alkaline Water Electrolyzer by Using an Expanded Mesh as a Bipolar Plate

Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm,electrodes,bipolar plates and end plates,etc.The existing industrial bipolar plate channel is concave-convex structure,which is manufactured by complicated and high-cost mold punching.This structure still results in uneven electrolyte flow and low current density in the electrolytic cell,further increasing in energy consumption and cost of AWE.Thereby,in this article,the electrochemical and flow model is firstly constructed,based on the existing industrial concave and convex flow channel structure of bipolar plate,to study the current density,electrolyte flow and bubble distribution in the electrolysis cell.The reliability of the model was verified by comparison with experimental data in literature.Among which,the electrochemical current density affects the bubble yield,on the other hand,the generated bubbles cover the electrode surface,affecting the active specific surface area and ohmic resistance,which in turn affects the electrochemical reaction.The result indicates that the flow velocity near the bottom of the concave ball approaches zero,while the flow velocity on the convex ball surface is significantly higher.Additionally,vortices are observed within the flow channel structure,leading to an uneven distribution of electrolyte.Next,modelling is used to optimize the bipolar plate structure of AWE by simulating the electrochemistry and fluid flow performances of four kinds of structures,namely,concave and convex,rhombus,wedge and expanded mesh,in the bipolar plate of alkaline water electrolyzer.The results show that the expanded mesh channel structure has the largest current density of 3330 A/m^(2)and electrolyte flow velocity of 0.507 m/s in the electrolytic cell.Under the same current density,the electrolytic cell with the expanded mesh runner structure has the smallest potential and energy consumption.This work provides a useful guide for the comprehensive understanding and optimization of channel structures,and a theoretical basis for the design of large-scale electrolyzer.

基于多专家信息融合Fuzzy-EAHP的地面无人平台自主能力评估方法

针对地面无人平台自主能力评估结果受主观因素影响较大的问题,提出一种基于多专家信息融合的Fuzzy-EAHP方法用于地面无人平台自主能力评估。以地面无人平台的任务和使用环境为基础分析能力需求;从环境感知能力、越野机动能力、决策规划能力、通信交互能力、抗干扰容错能力5个方面,完成自主能力评估指标体系的构建;在计算指标权重时提出一种基于多专家信息融合的Fuzzy-EAHP方法,该方法通过融合专家的专业程度提高评估准确性,能够处理定性与定量指标共存的问题。实例分析结果表明,该方法能够为地面无人平台的自主能力提供科学、合理的评价。

Study of Rice Husks and Expanded Polystyrene Composites for Construction Applications

In the current context of environmental challenges, this study focuses on developing innovative and eco-friendly composites using rice husk and recycled expanded polystyrene. This dual-responsibility approach valorizes a by-product like rice husk, often considered waste, and reuses polystyrene, a plastic waste, thereby contributing to CO2 emission reduction and effective waste management. The manufacturing process involves dissolving recycled polystyrene into a solvent to create a binder, which is then mixed with rice husk and cold-compacted into composite materials. The study examines the impact of two particle sizes (fine and coarse) and different proportions of recycled polystyrene binder. The results show significant variations in the mechanical characteristics of the composites, with Modulus of Rupture (MOR) values varying from 2.41 to 3.47 MPa, Modulus of Elasticity (MOE) ranging from 223.41 to 1497.2 MPa, and Stiffness Coefficient (K) from 5.04 to 33.96 N/mm. These characteristics demonstrate that these composites are appropriate for various construction applications, including interior decoration, panel claddings, and potentially for furniture and door manufacturing when combined with appropriate coatings. This study not only highlights the recycling of agricultural and plastic waste but also provides a localized approach to addressing global climate change challenges through the adoption of sustainable building materials.

双腔圆形软组织扩张器在即刻乳房重建中的应用

目的:探讨双腔圆形软组织扩张器在即刻乳房重建中的应用价值。方法:选择2022年3月至2023年10月在北京大学第三医院行乳腺癌切除术后即刻埋置双腔圆形软组织扩张器的两期法假体乳房重建的连续16例患者的病例资料进行回顾分析,探讨双腔圆形扩张器的扩张理念、埋置方式、型号选择,总结扩张效果以及并发症发生率,Ⅱ期置换假体术后从乳房下皱襞位置、乳房突度、乳房容量三方面评价重建乳房的美学效果。结果:选用400 mL扩张器3例,600 mL扩张器13例。组织扩张中位周期为4.0(2.0,5.0)个月,平均注水扩张量(538.8±111.7)mL,上、下囊腔注水量比例平均为45.4%±8.4%。Ⅱ期假体置换过程中下皱襞位置均未再进行调整,置换假体的中位体积为395(345,410)mL。围术期1例患者扩张期间出现血清肿,局部抽吸后好转。Ⅱ期术后平均随访(9.0±3.6)个月,重建乳房美学评价为优者占81.3%(13/16),假体包膜挛缩分级为Ⅰ级和Ⅱ级者占75.0%(12/16)。结论:应用双腔圆形软组织扩张器可有效扩张乳房下极皮肤,个性化控制乳房上、下极扩张比例,有效避免扩张期间的扩张器上方移位,从而为Ⅱ期假体置换提供良好基础。

扩展量子阱中负离子的光剥离动力学

本研究运用经典闭合轨道理论(COT)深入探究了扩展量子阱中的氢负离子的光剥离动力学,并推导出了相应的光剥离截面(PCS)表达式.由于量子囚禁效应,剥离截面上出现一个与量子阱有关的振荡因子.结果显示光剥离截面的振荡因子对扩展量子阱的阱壁速率的依赖极为敏感:当量子阱处于静态时,光剥离截面呈现出规则的锯齿状结构.当阱壁开始移动后,这种规则的锯齿结构变得不规则.随着阱壁移动速率的增大,PCS中的振荡结构变化复杂.此外光剥离截面中的振荡还与氢负离子与两个运动阱壁之间的初始距离即阱宽紧密相关:阱宽越窄,电子被局域的空间越狭小,电子受到的量子约束越强,截面上的振荡振幅越大,当阱宽增大时,电子受到的量子约束效应就会减弱,当阱宽增大到一定程度时,量子阱不再体现出明显的量子约束效应,光剥离截面趋向光滑背景项.因此,通过调整量子阱的初始尺寸、量子阱的扩展速率可实现对扩展量子阱中氢负离子光剥离截面的精确调控.本研究所揭示的现象颇具趣味性,且所采用的方法具有普适性,可为未来针对更复杂动态量子阱中光剥离截面的研究提供指导.

温度对高聚物浆液在裂隙中扩散特性影响研究

具有自膨胀特性的高聚物注浆材料已广泛应用于岩体加固工程,但关于其注浆机理尚缺乏深入认识。近期试验研究表明,温度对自膨胀高聚物浆液的流动扩散过程具有显著影响,原因在于温度变化会改变高聚物浆液化学反应进程,进而影响其扩散行为。为深入揭示温度对高聚物浆液在裂隙中扩散行为的影响机制,以一种工程中应用的自膨胀聚氨酯高聚物浆液为对象,基于浆液聚合反应机理和计算流体动力学理论,用准三维有限体积法离散浆液流动控制方程,用三维有限体积法离散裂隙壁热传导方程,建立模拟分析高聚物浆液在裂隙中膨胀扩散过程的热-流耦合仿真模型,实现对浆液化学反应进程、流场和“浆液-裂隙”体系温度场的耦合求解。开展不同注浆量、预热温度条件下无水平板裂隙高聚物注浆模型试验,通过浆液扩散范围、密度、温度等实测数据与计算结果的对比,验证所建立数值模型的适用性。在此基础上,分析预热温度、环境温度对浆液在平板裂隙中扩散行为的影响,结果表明,相同环境温度条件下,随着浆液预热温度升高,浆液扩散速率及升温速度加快,峰值温度增大,达到峰值点时刻越早;相同预热温度条件下,环境温度越高,浆液扩散速率越快,扩散半径越大;当浆液预热温度或环境温度升高至一定值时,浆液最终扩散范围不再发生明显改变;随着环境温度降低,所需的浆液最低预热温度逐渐增大。该文工作对高聚物裂隙注浆浆液预热温度设定具有一定指导作用。

社区同群效应与居民网络消费扩容提质

在百年未有之大变局下,扩内需、促消费已成为推动经济高效循环、满足人民美好生活需要的关键途径。作为人际互动与社会关系构建的关键场所,社区居民所形成的关系网络,不仅能强化居民之间的相互依赖,也能使居民消费行为产生同群效应。社区同群效应的信息传递与知识溢出,在促进居民网络消费扩容提质的同时,可以通过增加网络消费信贷、提升消费等级和降低居民依赖心理,使得低于参考点的居民受到激励,实现网络消费的扩容提质,这一点在男性和银发群体以及处于中小城市和农村地区的居民中表现得更为明显。社区同群效应对居民网络消费所产生的这种积极作用,为建立社区交流机制、设计符合居民需求特点的网络消费信贷体系、树立理性消费观和构建能释放内需动力的消费机制提供了新的实证证据,也丰富了居民消费领域的研究。

胃癌患者一级亲属胃癌筛查干预的应用效果

目的分析基于拓展平行过程理论的胃癌筛查行为干预方案对胃癌患者一级亲属胃癌筛查行为的影响。方法选择2024年1—3月在四川省资阳市雁江区人民医院未完成胃癌筛查的胃癌患者一级亲属88人作为研究对象,随机分为实验组和对照组两组,每组各44人。对照组接受常规健康宣教;实验组接受拓展平行过程理论的胃癌筛查干预方案,在干预前后采用胃癌认知问卷、胃癌拓展平行过程问卷对两组人员进行测定,对比胃镜筛查率。结果干预后实验组的胃癌认知问卷、胃癌拓展平行过程问卷得分高于对照组,胃镜筛查率高于对照组,差异具有统计学意义(P<0.001)。结论运用基于拓展平行过程理论的胃癌筛查行为干预方案能有效提高胃癌患者一级亲属胃癌认知、胃癌风险和胃癌筛查感知,促进胃癌筛查实施,助力胃癌高风险人群健康管理。

论《广瘟疫论》透疫四法对吴又可透疫理念的继承与发挥

吴又可善用透法治疗疫病,对后世影响深远。清代名医戴天章在吴氏学说基础上撰成《广瘟疫论》,书中对通腑透邪、逐瘀泄热、开达膜原、滋养透邪透疫四法论述尤为深入,具有重要指导意义。本文深入剖析戴天章《广瘟疫论》透疫四法,主要包括开达膜原明辨表里,注重“孤邪”;通腑透邪力辟寒温,“三分”指征,细化治方;逐瘀泄热倡用“蓄血三焦辨证”;论广滋养透邪,增述“五变”,从中探寻其对吴又可透疫理念的继承与发挥,如疫邪在半表半里之时达原饮和柴胡剂之运用区分、开达膜原之“孤邪”加味法、通腑透邪六大用药手法、“厥阴蓄血”证治等,以期对现代临床提供助力。

一种基于磁集成的零输入电流纹波可扩展高增益DC-DC变换器

为减小传统DC-DC变换器中存在输入电流纹波大、开关管电压应力高和电压增益低等问题,提出一种基于磁集成的零输入电流纹波可扩展高增益DC-DC变换器。该变换器将磁集成技术与耦合电感纹波抑制技术结合,仅采用一个磁芯元件,既可消除输入电流纹波,又可获得高电压增益,并可形成一系列扩展单元,进一步提升电压增益,减小开关器件的电压应力。详细分析变换器的工作原理、稳态性能、增益扩展、磁集成原理和零输入电流纹波特性。为验证所提变换器相关理论的可行性,搭建一台140 W、24 V/400 V的实验样机,实验结果基本与理论分析一致。

石蜡基复合相变储能砂浆的制备及性能研究

以石蜡和膨胀石墨为原材料,通过熔融吸附法制备石蜡/膨胀石墨复合相变材料,将相变材料掺入水泥中制备了石蜡基复合相变储能砂浆。通过FT-IR、水化放热测试、SEM、力学和热性能分析,研究了试样的物相结构、微观形貌、力学性能和导热性能。结果表明,石蜡和膨胀石墨是通过物理作用形成了石蜡/膨胀石墨复合相变材料,复合相变材料添加到砂浆中会以颗粒状的形式分散在水泥浆体中,使砂浆表面变得粗糙。相变材料的添加降低了砂浆水化放热速率和水化累积放热量。相变储能砂浆的抗压强度随相变材料的添加不断降低,相变材料添加量20%的储能砂浆的抗压强度为最低值10.63 MPa,较纯砂浆降低了34.18%,密度和导热系数降低至最小值,分别为1730.2 kg/m^(3)和0.372 W/(m·K);蓄热系数和比热容达到最大值,分别为16.24 W/(m^(2)·K)和1.592 J/(kg·℃)。箱体模型动态热性能分析表明,相变材料添加后延缓了最高温度到来的时间,降低了箱体的最高温度,相变材料添加量20%的储能砂浆的最高温度为28.0℃,最高温度到来的时间为8385 s。

“大思政课”视域下大学生就业能力培养的困境与路径研究

“大思政课”视域下大学生就业能力培养的研究,是基于深化高等教育改革创新、提升高校人才培养实效的战略考量,是新时代中国特色社会主义教育强国建设的重要探索与实践。文章分析了“大思政课”视域下大学生就业能力培养的内涵,指出“大思政课”视域下大学生就业能力培养面临着与专业教育教学、校园文化、网络文化建设以及与社会实践有机结合不充分等困境。通过对困境的分析,文章提出提升大学生就业能力包括将大学生就业能力培养融入课程教育教学、融入校园文化、融入网络文化建设以及融入社会实践这样几条路径。

整体性治理视域下巩固拓展脱贫攻坚成果与乡村振兴有效衔接研究

2020年年底,我国全面打赢脱贫攻坚战后全面建成小康社会,巩固拓展脱贫攻坚成果与乡村振兴有效衔接成为目前重要且紧迫的工作任务。巩固拓展脱贫攻坚成果与乡村振兴衔接具有跨领域性和多元繁杂性,二者衔接存在政策衔接不畅、资源配置分散、行动实践缺乏双向协同、治理结构模糊等“碎片化”问题。破解二者衔接所凸显的“碎片化”现象亟须借助于以“承担公共责任,满足公众需求”为根本指向,以“协调、整合”为核心的整体性治理理论提供解决思路。因此,基于整体性治理视角提出解决二者衔接进程中“碎片化”问题的关键举措:整合政策冲突,做实政策衔接;加强资源整合,实现资源有效衔接;健全协同合作的工作机制,确保行动精确衔接;优化组织协同,构筑多元治理结构。为巩固拓展脱贫攻坚成果和乡村振兴的全面实施,加快农业农村现代化建设和实现全民共同富裕提供实践研究。

变“三重锈带”为“四新突破”东北“加力振兴论”探讨

在2020年出版的«中国东北转型通论»基础上,针对原提出的“三重锈带”,从理论和实践结合上对东北“加力振兴论”进行了新的探讨,提出变“三重锈带”为“四新突破”的主张.其要点主要包括四个方面:加力振兴首先往体制上“加”———切实推进东北体制的“基因再造”,真正构建起高水平社会主义市场经济体制;针对“结构锈带”,建议以“四拓”(即“拓需”“拓数”“拓区”“拓绿”)为基本思路,着力开拓创新四方面经济结构;加力振兴往开放上“加力”———以“向北开放”为契机,把东北打造成国家“对外开放的新前沿”;针对“文明方式锈带”,以培育新时代文明为战略取向,在东北切实促进中外文明包容与交融.

基于EAHP的尾矿库溃坝风险多级模糊综合评价研究

针对尾矿库溃坝风险评价中存在群决策的主观随意性和语言模糊不确定性等问题,建立了基于可拓层次分析法(Extension Analytic Hierarchy Process,EAHP)的尾矿库溃坝风险多级模糊综合评价模型。采用可拓区间判断矩阵全面客观地描述了各位专家对该尾矿库溃坝风险评价指标权重的模糊意见和偏好,利用各位专家与专家组意见的偏差比重确定各位专家的重要性系数,并引入一致性系数α和θ处理可拓综合区间判断矩阵R,进而确定指标权重系数ωj,凸显了各位专家在尾矿库溃坝风险群决策中的不同作用,简化了可拓区间判断矩阵一致性检验过程,提高了指标权重的准确性。将建立的尾矿库溃坝风险多级模糊综合评价模型应用于杨家湾尾矿库溃坝风险评价中。评价结果表明:该尾矿库的溃坝风险等级为安全,且坝体失稳和洪水漫顶对该尾矿库的安全影响较大,与杨家湾尾矿库日常管理的实际情况相符。该方法有效解决了尾矿库溃坝风险分析中的权重群决策问题,既避免了专家意见的遗失,又降低了专家主观判断的随意性对评价结果带来的不利影响,提高了尾矿库溃坝风险分析的有效性。

基于Fuzzy-EAHP的无人驾驶车辆智能行为评价

鉴于国内外智能车比赛采用的任务驱动的评价方法,导致参赛队伍为完成任务采取保守的方式,因而背离了技术发展的目的,提出了一种可拓层次分析法与模糊综合评价法相结合的无人驾驶车辆智能行为的模糊-可拓层次分析(Fussy-EAHP)评价法,克服了层次分析法在解决专家经验判断的模糊性问题和判断矩阵一致性方面的不足,有效避免了层次分析法中的大量试算工作,能合理地计算出无人驾驶车辆智能行为各个指标的权重。其量化结果能较好地反映实际情况,且可方便地转化成具体的得分数,便于结果的直观比较或排序。对FC 2011参赛车辆进行评价结果表明,该方法实用、可靠、方便、合理,不仅能对单个指标进行评价,还能对各级指标做出综合评价,并进一步找出无人驾驶车辆各项指标的不足,指明改进的方向。

基于Spearman-EAHP变权灰云聚类模型的尾矿库安全评价

针对尾矿库安全评价中存在"指标权重群决策意见不易统一"和"安全评价等级信息具有随机性和模糊性"等问题,提出了Spearman-EAHP的变权非对称灰云聚类模型。首先,引入Spearman系数对指标重要性排序进行预处理和一致性检验,考虑指标理想序和指标实测数据非线性变化的影响,建立了基于EAHP法的指标变权算法,全面反映了专家对指标排序主观意见的模糊性及差异和尾矿库安全状态差异对指标权重的影响,也客观衡量了专家在赋权中的不同作用。采用基于Spearman-EAHP法的变权非对称灰云聚类模型,对湖南省3座尾矿库的安全状态进行评价,根据尾矿库安全评价的数据特征,构建适中测度、上限测度和下限测度等正态灰云函数,并考虑指标权重影响,评价结果表明,3座尾矿库安全评价等级为Ⅲ级,与实际情况相符,验证了该模型方法的可行性和有效性。