Chlorophyll adsorption on acid-activated clay

An acid-activated clay (Çanakkale montmorillonite from Turkey) was used to adsorb chlorophyll from hexane solutions. The phenomenon seems to be mainly driven by the interaction of chlorophyll with acid sites. The adsorption of chlorophyll on Brönsted acid sites was indicated by a characteristic infrared band for the -OH group at 3671 cm^?1. The variations in the structure of clay mineral and chlorophyll during adsorption have been examined by differential thermal analysis, thermogravimetry and infrared spectroscopy of the activated clay before and after adsorption of chlorophyll. Oxidation of adsorbed chlorophyll was completed at quite a high temperature.     

Synthesis and dielectric properties of polystyrene‐clay nanocomposite materials

Polystyrene‐clay nanocomposite (PsCN) materials were synthesized and their properties of crystallinity, thermal behavior, and dielectric characteristics were investigated. A polymerizable cationic surfactant, [2‐(dimethylamino)ethyl]triphenylphonium bromide, was used for the intercalation of montmorillonite (MMT). The organophilic MMT was prepared by Na⁺‐exchanged MMT and ammonium cations of a cationic surfactant in an aqueous medium. Organophilic styrene monomers were intercalated into the interlayer regions of organophilic clay hosts followed by a free‐radical polymerization. Exfoliation to 2 wt % MMT in the polystyrene (PS) matrix was achieved as revealed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal properties by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were also studied. The dielectric properties of PsCNs in the form of film with clay loading from 1.0 to 5.0 wt % were measured under frequencies of 100 Hz–1 MHz at 25–70°C. A decreased dielectric constant and low dielectric loss were observed for PsCN materials. The dielectric response at low frequency that originated from dipole orientation was suppressed due to the intercalation of clay materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1368–1373, 2004     

深厚覆盖层上高心墙坝地震惯性力动态分布系数研究

对于强震区坐落在深厚覆盖层(深度超过50 m)上的高土石坝,通过拟静力稳定分析结果初步判定其抗震稳定性是抗震设计的主要内容,其中水平向地震惯性力沿坝基覆盖层至坝顶的动态分布系数是关键。然而,现行《水工建筑物抗震设计标准》(GB 51247—2018)中地震惯性力动态分布系数多基于坐落在基岩上的高土石坝的动力响应规律确定,现有动态分布系数忽略了深厚覆盖层和地震动强度对地震动传播规律的影响。因此,以坐落在深厚砂砾石覆盖层上150 m级高黏土心墙堆石坝为研究对象,结合现行土石坝设计规范和国内已建高土石坝实例,基于统计平均的方法确定了坝顶宽度、坝料分区、坝坡坡比、覆盖层材料的静、动力特性等关键参数,深入探讨了150 m级高黏土心墙堆石坝在小震(0.1 g)、中震(0.2 g)和大震(0.4 g)规范谱地震动作用下不同深度砂砾石料覆盖层的动力响应分布规律,进而总结归纳出不同深度覆盖层下150 m级高黏土心墙堆石坝的水平向地震惯性力的动态分布系数,将其引入到拟静力法稳定分析中,最后基于最危险滑动面和最小安全系数与现行规范所得结果进行对比分析。研究结果表明,小震(0.1 g)和中震(0.2 g)下采用文中推荐的考虑深厚覆盖层和地震动输入强度影响的水平向地震惯性力动态分布系数时将得到更符合工程实际的评价结果。研究成果可为深厚覆盖层上的高土石坝抗震设计提供参考依据。     

考虑恶劣天气的班轮多阶段重调度方法

受恶劣天气影响的船舶调度是一个非常复杂的优化问题,也是班轮公司重点关注的问题之一。为此,针对某航运网络上的一家班轮公司的所有营运船舶,以获知设计的多阶段重调度机制时段内最新预报的天气信息和这些船舶的实时位置为前提,重点考虑班轮船期表的限制并兼顾港口间航速变化和船舶容量等现实约束,构建了以固定计划期内所有船舶的航运总成本最小为优化目标的非线性数学模型,并设计了嵌入基因修复算子的改进遗传算法用于求解该模型。由此,可以给出集成租船直运、跨航线调船、反挂和货物中转等解决策略的最佳多阶段重调度方案。通过对大、中、小规模的算例进行实验,实验结果表明,可知与传统等待办法相比,多阶段重调度节约了总航运成本的15%以上,验证了所提模型和方案的有效性;与Cplex相比,改进遗传算法的运算效率大大提高,且偏差值均在5%以内,而与蚁群优化（ACO）算法、禁忌搜索（TS）算法、量子差分进化（QDE）算法相比,改进遗传算法能在有效时间内降低10%左右的成本,验证了算法的科学性。所提方法可为班轮公司的实际船舶调度提供参考。     

细菌对红黏土抗剪强度的影响

为了探究土壤原生细菌对红黏土强度的影响,通过对红黏土中天然赋存的原生细菌进行富集培养,并在红黏土重塑试样中添加培养后的细菌菌液,通过土工试验和电镜试验分析红黏土物理力学性质和微观结构的变化。结果表明:随着细菌的掺入,三轴试样的破坏峰值和压缩模量都有所提高,并且随时间的增长,呈现先增大后减小的趋势;同时从电镜图像上来看,细菌的掺入使得红黏土中粉粒含量有所增加,相应的黏粒含量下降。研究结果可为进一步研究单一的细菌种类对红黏土物理力学性质和微观结构的影响提供参考。     

NH3·H2O对桂林地区红黏土工程特性的影响试验研究

为研究氮肥污染对桂林红黏土物理力学性质的影响,使用氨水(NH₃·H₂O)溶液对具有代表性的桂林雁山红黏土进行浸泡,考虑氨水质量分数(0,4.5%,9.0%,13.5%,18.0%)和养护时间(1,7,14 d)双因子因素,通过室内试验,分析氨水污染对桂林雁山红黏土物理力学性质的影响规律。试验结果表明:随着氨水质量分数及养护时间的增加,桂林雁山红黏土的质量、含水率、相对密度和液塑限均增大,压缩模量减小,土体压缩性增强;碱-土作用是引起红黏土物理力学性质发生变化的主要原因,其相互作用导致红黏土颗粒间的胶结物被溶解后又重新生成絮状物,使其原本稳定的结构状态发生改变。     

脱湿过程中红黏土热导率的变化试验研究

自然状态下岩土体中的三相组成处于动态变化之中,对土体热传导性能的准确测试造成困难,通过热导率脱湿曲线(TCDC)可间接获取土体的传热性能。为此,以桂林红黏土为研究对象,采用压力板仪和KD2 Pro土壤热特性分析仪,研究了红黏土在脱湿过程中热导率的变化规律。试验结果表明:在进气值之前,土体饱和度不变,3种干密度的土体热导率都有小幅度增加,此阶段主要与吸力变化引起的土体密实度变化有关;当吸力超过进气值后,热导率随饱和度减小逐渐减小,此阶段含水率为影响热导率的主要因素。基于热导率试验结果,采用Lu模型和William模型对红黏土脱湿过程中热导率变化曲线进行拟合,整体上2模型对试验结果拟合较好,可以用于红黏土脱湿过程中热导率变化的模拟。     

利用废旧胶粉改善红黏土工程性质试验研究

随着废旧轮胎的日益剧增,回收利用率较低带来了严重的环保问题。利用废旧轮胎胶粉对红黏土进行改良,形成混合土。通过标准轻型击实试验、等效击实试验、直剪试验以及渗透试验,研究了不同胶粉掺量(0%,3%,8%,15%,25%)和不同含水量对混合土的击实特性、抗剪强度特性以及渗透性的影响。研究结果表明:①混合土的最大干密度比原状红黏土低,且胶粉的掺量越大,最大干密度越小;②胶粉掺量增大,标准击实试验的最优含水率增大,等效击实试验的最优含水率有减小趋势;③胶粉掺量不超过15%时,随着胶粉掺量增大,混合土的抗剪强度增大,内摩擦角增大,且出现应变硬化现象:④标准击实下,胶粉掺量为8%时,混合土的渗透速率变化不明显;但胶粉掺量增加到15%时,混合土的渗透速率显著提高,提升幅度达到97.3%。研究成果可为贵州地区今后废旧胶粉的循环利用和胶粉改良红黏土的工程运用提供参考。     

TRD工法水泥土墙现场取芯的三轴渗透试验

为提高TRD工法在国内的应用水平,通过对天津市某基坑项目TRD水泥土墙进行现场取芯,在实验室内进行三轴渗透试验,得出水泥土墙在不同水泥掺入比条件下的芯样渗透系数曲线、不同养护龄期条件下芯样的渗透特性关系和不同土层条件下的芯样渗透系数对比,并分析产生上述曲线关系的原因,得出满足基坑止水要求的水泥经济掺入比和合理的养护龄期,给出了不同龄期下TRD水泥土墙渗透系数与水泥掺入比的经验公式.结果表明,TRD工法优于传统的SM W工法.     

Optimized design of biconical liner by orthogonal method

A biconical liner was optimized to improve its penetration ability. Its formation and penetration mechanism was studied through numerical simulation and experiments. And the influence of different liner geometry sizes on the jet performance was analyzed using the orthogonal method. The liner formed the high-speed jet with an explosively formed projectile. The small angle 2α remarkably influenced the jet speed which was inversely proportional to 2α. And the liner thickness t' and large angle 2β had highly significant effect on the projectile speed. The liner was optimized at t' = 0. 14 cm,2α = 50°,2β = 135°,N = 0. 4 or 0. 5,when its jet speed respectively is at 6 613 m /s and 6 839 m /s and projectile speed is at 2 247 m /s and 2 095 m /s,steel target penetration is at 8. 24 cm and 8. 31 cm,and aperture is in 2. 12 cm and 2. 08 cm. The results show that target is penetrated by the high-speed jet and high-speed projectile resulting into double damages. The penetration ability is improved greatly.