Experimental Study on Improved Engineered Cementitious Composite Using Local Material

Engineered Cementitious Composite (ECC) is a cement based material with ultra-high ductility and strength in tension. This material is a kind of highperformance fiber-reinforced cementitious composite materials (HPFRCCs) reinforced with short fibers and characterized by tight multiple cracking. These characteristics of ECC make it applicable to increase the capacity and the ductility of structural elements so that structural design is economic and sustainable. This paper presents an extended evaluation of Improved Engineered Cementitious Composites (IECC) for the use in the strengthening of masonry in filled reinforced concrete frames. IECC is a mixture of cement, fly ash, water, sand, quartz powder and poly-vinyl alcohol fibers with a better quality of tensile strain rather than common ECC. Two types of fine sand and quartz powder used in this study as filler to improve ECC behavior. Also, to show the effect of fly ash on IECC properties, five different mixtures were considered with various fly ash ratios. Different mixtures of IECC using fine aggregates produced in Iran were selected to find out how the aggregates and fly ash would affect IECC performance. The results show that the optimized mixture has the best characteristics including tensile strength and strain. Also, three-dimensional diagrams were used to compare the properties of different mixtures of IECC more effectively and to represent the influence of the range of fly ash ratios so that it can be opted based on design objectives such as ECC properties, costs and structural parameters and demands. These diagrams show the behavior of IECC which its fly ash content ratio in the binder is 50% to 67%.

Recent progress in Ni-rich layered oxides and related cathode materials for Li-ion cells

Undoubtedly,the enormous progress observed in recent years in the Ni-rich layered cathode materials has been crucial in terms of pushing boundaries of the Li-ion battery(LIB)technology.The achieved improvements in the energy density,cyclability,charging speed,reduced costs,as well as safety and stability,already contribute to the wider adoption of LIBs,which extends nowadays beyond mobile electronics,power tools,and electric vehicles,to the new range of applications,including grid storage solutions.With numerous published papers and broad reviews already available on the subject of Ni-rich oxides,this review focuses more on the most recent progress and new ideas presented in the literature references.The covered topics include doping and composition optimization,advanced coating,concentration gradient and single crystal materials,as well as innovations concerning new electrolytes and their modification,with the application of Ni-rich cathodes in solid-state batteries also discussed.Related cathode materials are briefly mentioned,with the high-entropy approach and zero-strain concept presented as well.A critical overview of the still unresolved issues is given,with perspectives on the further directions of studies and the expected gains provided.

Dynamic Characteristics of Functionally Graded Timoshenko Beams by Improved Differential Quadrature Method

This study proposes an effective method to enhance the accuracy of the Differential Quadrature Method(DQM)for calculating the dynamic characteristics of functionally graded beams by improving the form of discrete node distribution.Firstly,based on the first-order shear deformation theory,the governing equation of free vibration of a functionally graded beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam axial displacement,transverse displacement,and cross-sectional rotation angle by considering the effects of shear deformation and rotational inertia of the beam cross-section.Then,ignoring the shear deformation of the beam section and only considering the effect of the rotational inertia of the section,the governing equation of the beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam transverse displacement.Based on the differential quadrature method theory,the eigenvalue problem of ordinary differential equations is transformed into the eigenvalue problem of standard generalized algebraic equations.Finally,the first several natural frequencies of the beam can be calculated.The feasibility and accuracy of the improved DQM are verified using the finite element method(FEM)and combined with the results of relevant literature.

Advanced preparation and application of bimetallic materials in lithium-sulfur batteries:A review

Lithium-sulfur(Li-S)batteries are considered highly promising as next-generation energy storage systems due to high theoretical capacity(2600 Wh kg^(-1))and energy density(1675 mA h g^(-1))as well as the abundant natural reserves,low cost of elemental sulfur,and environmentally friendly properties.However,several challenges impede its commercialization including low conductivity of sulfur itself,the severe“shuttle effect”caused by lithium polysulfides(LiPSs)during charge–discharge processes,volume expansion effects and sluggish reaction kinetics.As a solution,polar metal particles and their compounds have been introduced as the main hosts for sulfur cathode due to their robust catalytic activity and adsorption capability,effectively suppressing the“shuttle effect”of Li PSs.Bimetallic alloys and their compounds with multi-functional properties exhibit remarkable electrochemical performance more readily when compared to single-metal materials.Well-designed bimetallic materials demonstrate larger specific surface areas and richer active sites,enabling simultaneous high adsorption capability and strong catalytic properties.The synergistic effect of the“adsorption-catalysis”sites accelerates the adsorptiondiffusion-conversion process of Li PSs,ultimately achieving a long-lasting Li-S battery.Herein,the latest progress and performance of bimetallic materials in cathodes,separators,and interlayers of Li-S batteries are systematically reviewed.Firstly,the principles and challenges of Li-S batteries are briefly analyzed.Then,various mechanisms for suppressing“shuttle effects”of Li PSs are emphasized at the microscale.Subsequently,the performance parameters of various bimetallic materials are comprehensively summarized,and some improvement strategies are proposed based on these findings.Finally,the future prospects of bimetallic materials are discussed,with the hope of providing profound insights for the rational design and manufacturing of high-performance bimetallic materials for LSBs.

Quality Improvement of Granular Wastes-The Effective Way to Recycle Secondary Raw Building Materials

Granular wastes have negative effects on the environment due to contamination. On the other hand, stony components in granular wastes have a potential good perspectives for utilization in civil engineering works as secondary raw building materials. To reuse such materials without environmental risks, all contaminants must be removed or reduced to an acceptable level. Therefore liberation of materials is an important step in waste treatment. For this purpose, separation and cleansing techniques are suitable. Based on the analysis of contaminants in wastes, it is discussed how to select suitable techniques. The rules for technique selection and processes for quality improvement are set up. To evaluate the environmental quality and technical quality of output products, it is necessary to check leaching behaviours and physical properties.

Effective Utilization of Concrete Sludge as Soil Improvement Materials

The amount of muddy soil generated from various kinds of construction sites is always problematic. It is very difficult to treat muddy soil because of its low strength and high water content. But, the reuse of muddy soil is necessary to reduce the total amount of industrial wastes. Surplus concrete is also in a similar situation. Coarse and fine aggregates are removed from surplus concrete as an intermediate treatment, however, concrete sludge still remains. The authors propose a reuse method that involves the muddy soil being mixed with concrete sludge as an improvement material. The possibility of the utilization of concrete sludge was investigated through laboratory experiments. As a result, it was found that the unconfined compressive strength of the improved soil mixed with concrete sludge increased as the curing proceeded.

Advances in Mn‑Based Electrode Materials for Aqueous Sodium‑Ion Batteries

Aqueous sodium-ion batteries have attracted extensive attention for large-scale energy storage applications,due to abundant sodium resources,low cost,intrinsic safety of aqueous electrolytes and eco-friendliness.The electrochemical performance of aqueous sodium-ion batteries is affected by the properties of electrode materials and electrolytes.Among various electrode materials,Mn-based electrode materials have attracted tremendous attention because of the abundance of Mn,low cost,nontoxicity,eco-friendliness and interesting electrochemical performance.Aqueous electrolytes having narrow electrochemical window also affect the electrochemical performance of Mn-based electrode materials.In this review,we introduce systematically Mn-based electrode materials for aqueous sodium-ion batteries from cathode and anode materials and offer a comprehensive overview about their recent development.These Mn-based materials include oxides,Prussian blue analogues and polyanion compounds.We summarize and discuss the composition,crystal structure,morphology and electrochemical properties of Mn-based electrode materials.The improvement methods based on electrolyte optimization,element doping or substitution,optimization of morphology and carbon modification are highlighted.The perspectives of Mn-based electrode materials for future studies are also provided.We believe this review is important and helpful to explore and apply Mn-based electrode materials in aqueous sodium-ion batteries.

Designing high-efficiency light-to-thermal conversion materials for solar desalination and photothermal catalysis

Light-to-thermal conversion materials(LTCMs)have been of great interest to researchers due to their impressive energy conversion capacity and wide range of applications in biomedical,desalination,and synergistic catalysis.Given the limited advances in existing materials(metals,semiconductors,π-conjugates),researchers generally adopt the method of constructing complex systems and hybrid structures to optimize performance and achieve multifunctional integration.However,the development of LTCMs is still in its infancy as the physical mechanism of light-to-thermal conversion is unclear.In this review,we proposed design strategies for efficient LTCMs by analyzing the physical process of light-tothermal conversion.First,we analyze the nature of light absorption and heat generation to reveal the physical processes of light-to-thermal conversion.Then,we explain the light-to-thermal conversion mechanisms of metallic,semiconducting andπ-conjugated LCTMs,and propose new material design strategies and performance improvement methods.Finally,we summarize the challenges and prospects of LTCMs in emerging applications such as solar water evaporation and photothermal catalysis.

New Adhesive Material for Construction Joint of Tunnel Lining

The new adhesive material for the construction joints of tunnel lining(named as SZC) was studied based on the structural characteristics of interfaces and the characteristic of bonding construction, and the performance indexes were verified by tests. The experimental results show that the adhesive capability of interface is improved effectively by using SZC material, the properties, such as anti-freezing, erosion-resistance and anti-shrinkage are improved greatly as well as durability.

Improved anti-Stokes energy transfer between rare earth ions in Er(0.5)Yb(9.5):FOV oxyfluoride vitroceramics explains the strong color reversal

The widely used energy transfer theory is a foundation of luminescence, in which the rates of Stokes and anti-Stokes processes have the same calculation formula. An improvement on the anti-Stokes energy transfer to explain the fluorescence intensity reversal between the red and green fluorescence of Er（0.5）Yb（9.5）：FOV is reported in the present article. The range of the intensity reversal Z was measured to be 877. Dynamic processes for 16 levels were simulated. A coefficient, the improvement factor of the intensity ratio of Stokes to anti-Stokes processes in quantum Raman theory compared to classical Raman theory, is introduced to successfully describe the anti-Stokes energy transfer. A new method to calculate the distance between the rare earth ions, which is critical for the energy transfer calculation, is proposed. The validity of these important improvements is also proved by experiment.

Preparation of ZnO/GO composite material with highly photocatalytic performance via an improved two-step method

ZnO/graphene oxide（ZnO/GO） composite material,in which ZnO nanoparticles were densely coated on the GO nanosheets,was successfully prepared by an improved two-step method and characterized by IR, XRD,TEM,and UV-vis techniques.The improved photocatalytic property of the ZnO/GO composite material,evaluated by the photocatalytic degradation of methyl orange（MO） under UV irradiation,is ascribed to the intimate contact between ZnO and GO,the enhanced adsorption of MO,the quick electron transfer from excited ZnO particles to GO sheets and the activation of MO molecules viaπ-πinteraction between MO and GO.

Magnetic force improvement and parameter optimization for magnetic abrasive polishing of AZ31 magnesium alloy

The magnetic force acting on workpiece to be machined plays a significantly important role in magnetic abrasive polishing process.But in a case of polishing nonferrous materials,the strength of magnetic force is very low and it leads lower polishing efficiency.The magnesium alloy that has superior mechanical properties for industrial application such as a lightweight and high specific strength is one of the most famous nonferrous materials.An improving strategy of the magnetic force for the AZ31 magnesium alloy installed with a permanent magnet was proposed and experimental verification was carried out.For the proposed strategy,the effect of process parameters on the surface roughness of the AZ31 magnesium alloy was evaluated by a design of experimental method.

广西大新红黏土工程地质特性及路基处治措施

研究目的:红黏土因其特殊的工程性质,容易引起边坡出现裂隙、垮塌、不均匀沉降等病害,对工程质量、安全、造价造成极大影响。本文对红黏土进行详细室内土工试验,分析研究红黏土的物理力学性特征,从而为红黏土边坡防护及填料利用提供相应的处治措施建议,以指导工程实践。研究结论:(1)该地区红黏土显示出高含水率、高饱和度、高孔隙比、高液限、高塑性、压缩性较小、黏聚力高、弱~中膨胀性的特征;(2)随深度增加,含水率、液限、孔隙比、液性指数、压缩系数逐渐增大,而黏聚力、压缩模量逐步降低,形成上硬下软的特征;(3)对红黏土路堑,提出采用“缓边坡、宽平台、固坡脚”的设计原则;(4)针对红黏土填料,提出根据击实后50 kPa下膨胀总率判定填料膨胀性,采取包边、加筋、设置垫层、无机结合料改良处治后用于路基填料;(5)本研究成果对广西红黏土地区勘察设计具有一定的参考价值。

藏东南冰碛体剪切特性受冻融循环的影响及改良

藏东南地区广泛分布着冰碛体堆积体,此土体严重影响工程安全。为了研究冰碛体的剪切性能并对其进行改良,运用相似原理配制出级配良好的冰碛体相似材料,分别在不同冻融循环次数和不同含水率的条件下,对冰碛体相似材料开展了直剪试验,同时掺入机油和粉煤灰外加剂进行三轴试验,研究其对冰碛体相似材料抗剪强度参数的影响。结果表明:(1)直剪试验过程中,随着垂直压力的增大,冰碛体的位移-剪应力曲线由弱应变软化型转变为弱应变硬化型。(2)含水率变化对冰碛体抗剪强度的升降受到冻融循环次数的影响。(3)冻融循环为5次是冰碛体材料抗剪强度的分界线。(4)机油和粉煤灰对冰碛体抗剪强度指标(咬合力和内摩擦角)的影响相反。

由石蜡基相变材料和煤渣改良的粉砂土的冻融性能

【目的】针对季节冻土区渠道的衬砌结构因冻融作用而受损的现状,同时为了解决石蜡基相变材料(phase change materials, PCM)的泄露,并满足煤渣的再利用需求,研究石蜡基PCM和煤渣对土体冻融性能的影响。【方法】以粉砂土为研究对象,选取石蜡基PCM和煤渣作为改良剂,制备石蜡基PCM改良土和石蜡基PCM-煤渣改良土;通过冻融循环作用下的体积变化率试验、无侧限抗压强度试验,微观结构及潜热研究土体的体积和无侧限抗压强度的变化。【结果】石蜡基PCM能抑制粉砂土的冻融变形,质量分数为8%时2种改良土的体积变化率最小;随着冻融循环次数的增加,土体的无侧限抗压强度均降低,降低速率先大后小;循环次数相同时,加入煤渣的改良土的无侧限抗压强度均大于未加入煤渣的;冻融循环9次后,石蜡基PCM质量分数为10%的石蜡基PCM改良土的无侧限抗压强度最低;2种改良土的结构比粉砂土更密实、稳定;潜热的吸收或释放延缓了土体冻融过程。【结论】将石蜡基PCM和煤渣共同掺入粉砂土,能控制土体的冻融变形且效果稳定,改善土体的冻融性能,减轻季节冻土区输水渠道衬砌结构的冻害,提高煤渣的利用率。

不确定情景下考虑灾民感知的应急物资调度研究

为解决大规模突发灾害给人民带来的生理与心理痛楚问题,考虑模糊需求情景下灾区道路受损、物资相对短缺、灾区需求紧迫度差异等因素,同时考虑灾民有限理性下物资竞争心理,运用前景理论刻画灾民对物资分配、运抵时间的综合感知,以灾区运输时间感知满意度最大、物资分配感知损失最小、运输成本最小为目标构建应急物资调度多目标优化模型,设计改进灰狼优化算法(Grey Wolf Optimizer,GWO)求解,引入混沌反向学习、差分进化、非线性收敛等策略实现对GWO算法的改进,并以2008年四川地震案例数据展开分析验证,依据模糊逻辑加权法选择合适的应急调度方案。研究表明,该模型可合理衡量有限理性下灾民综合感知,改进算法能够得出更加公平高效的调度方案,有效解决了灾后模糊需求情景下应急物资调度问题。

翅片增强空气式相变储能装置蓄热性能模拟研究

目的为解决空气式相变储能装置中存在的蓄热时间过长等问题,探究该装置蓄热性能的优化措施。方法利用FLUENT仿真软件对添加不同体积分数、厚度和高度翅片空气式相变储能装置的温度场进行数值模拟,并对模拟结果进行比较分析。结果翅片体积分数为15%,厚度为8 mm,高度为14 mm时,空气式相变储能装置蓄热时间缩短最显著,可缩短46.97%。结论翅片的添加对相变储能单元的熔化具有促进作用,通过优化翅片体积分数、厚度和高度参数,可以提高空气式相变储能装置的蓄热性能。

基于改进明瑟工资方程的河南省农业全要素生产率测算

【目的】探究河南省农业人力资本存量和物质资本存量的变化趋势,并以此为基础测算农业全要素生产率,分析促进河南省农业经济增长的主要因素。【方法】考虑到年龄对人力资本的影响,把年龄因素纳入到明瑟工资方程中,提出并利用改进明瑟工资方程估算了农业人力资本存量,结合永续盘存法估算了农业物质资本存量。在此基础上采用C-D生产函数模型测算出河南省农业全要素生产率。【结果】由于每年农业固定投资总额增幅较大,物质资本存量也在逐年增加。而由于农业从业人员转出较快,农业人力资本存量逐渐降低。在弹性系数作用下,物质资本存量与人力资本存量的乘积虽然在增长,但其增速低于农业产值的增速,进而农业全要素生产率呈现出上升趋势。【结论】继续强化农业物质资本的投入,提升农业从业人员的素质,以人力资本与物质资本组合的优化促进农业全要素生产率的提升,进而加快河南省农业强省战略的推进。

盐碱地改造用高效阻盐材料的制备及其性能研究

为改良盐碱土壤,制备了一种隔水阻盐性能优异的超疏水颗粒材料,构建隔水阻盐材料与蓄水模式结合的盐碱地改造体系。以大漠砂为芯材,通过表面覆膜进行疏水改性,探究树脂和微纳米辅材掺量对材料疏水性、抗渗性和透气性的影响规律。利用微型土柱模拟地下水盐迁移过程,探究材料的隔水性能和阻盐性能。结果表明,在树脂、疏水碳酸钙和纳米二氧化硅掺量分别为1.0%、0.8%和0.2%时,材料接触角达到153.6°,耐静水高度达230 mm,并维持良好的透气性能。在微型土柱模拟试验中,隔水阻盐材料对水分蒸发和盐分上移的抑制作用明显,蒸发抑制率为50%~70%,盐分抑制率大于99%且在20次阻盐循环后维持97.5%以上。

考虑三级调度网络的应急物资多资源动态调度问题研究

为解决重大公共卫生事件发生后的物资调度问题,运用SEIR模型预测需求点的各类受灾人群,构建需求预测模型;以综合物资分配满意度最大、综合运输时间满意度最大和综合救援成本最小为目标,采用多供应点、多配送中心、多需求点的三级调度网络,实现多周期、多资源的动态调度;引入混沌反向学习、非线性收敛因子、随机差分变异和贪婪选择策略改进灰狼优化算法,并对模型进行求解。结果表明,该模型可有效平衡物资调度的满意度与经济性,改进灰狼优化算法可得到更优越的调度方案,解决灾后多周期应急物资调度问题。