Rapid and high-capacity ultrasonic assisted adsorption of ternary toxic anionic dyes onto MOF-5-activated carbon: Artificial neural networks,partial least squares,desirability function and isotherm and kinetic study

The present paper focused on the ultrasonic assisted simultaneous removal of fast green (FG), eosin Y (EY) and quinine yellow (QY) from aqueous media following using MOF-5 as a metal organic framework and activated carbon hybrid (AC-MOF-5). The structure and morphology of AC-MOF-5 was identified by SEM, FTIR and XRD analysis. The interactive and main effects of variables such as pH, initial dyes concentration (mg L⁻¹), adsorbent dosage (mg) and sonication time (min) on removal percentage were studied by central composite design (CCD), subsequent desirability function (DF) permit to achieved real variable experimental condition. Optimized values were found 7.06, 5.68, 7.59 and 5.04 mg L⁻¹, 0.02 g and 2.55 min for pH, FG, EY and QY concentration, adsorbent dosage and sonication time, respectively. Under this conditions removal percentage were obtained 98.1%, 98.1% and 91.91% for FG, EY and QY, respectively. Two models, namely partial least squares (PLS) and multi-layer artificial neural network (ANN) model were used for building up to construct an empirical model to predict the dyes under study removal behavior. The obtained results show that ANN and PLS model is a powerful tool for prediction of under-study dyes adsorption by AC-MOF-5. The evaluation and estimation of equilibrium data from traditional isotherm models display that the Langmuir model indicated the best fit to the equilibrium data with maximum adsorption capacity of 21.230, 20.242 and 18.621 mg g⁻¹, for FG, EY and QY, respectively, while the adsorption rate efficiently follows the pseudo-second-order model.     

Rapid preparation of high electrochemical performance LiFePO4/C composite cathode material with an ultrasonic-intensified micro-impinging jetting reactor

A joint chemical reactor system referred to as an ultrasonic-intensified micro-impinging jetting reactor (UIJR), which possesses the feature of fast micro-mixing, was proposed and has been employed for rapid preparation of FePO₄ particles that are amalgamated by nanoscale primary crystals. As one of the important precursors for the fabrication of lithium iron phosphate cathode, the properties of FePO₄ nano particles significantly affect the performance of the lithium iron phosphate cathode. Thus, the effects of joint use of impinging stream and ultrasonic irradiation on the formation of mesoporous structure of FePO₄ nano precursor particles and the electrochemical properties of amalgamated LiFePO₄/C have been investigated. Additionally, the effects of the reactant concentration (C = 0.5, 1.0 and 1.5 mol L⁻¹), and volumetric flow rate (V = 17.15, 51.44, and 85.74 mL min⁻¹) on synthesis of FePO₄·2H₂O nucleus have been studied when the impinging jetting reactor (IJR) and UIJR are to operate in nonsubmerged mode. It was affirmed from the experiments that the FePO₄ nano precursor particles prepared using UIJR have well-formed mesoporous structures with the primary crystal size of 44.6 nm, an average pore size of 15.2 nm, and a specific surface area of 134.54 m² g⁻¹ when the reactant concentration and volumetric flow rate are 1.0 mol L⁻¹ and 85.74 mL min⁻¹ respectively. The amalgamated LiFePO₄/C composites can deliver good electrochemical performance with discharge capacities of 156.7 mA h g⁻¹ at 0.1 C, and exhibit 138.0 mA h g⁻¹ after 100 cycles at 0.5 C, which is 95.3% of the initial discharge capacity.     

液体薄层中的超声空化*

液体薄层中的超声空化,因其边界及所处空间的特殊性,而呈现出非常独特的空化结构和演化行为,在超声清洗、超声钎焊、表面处理、近场声悬浮、超声化学等领域都有所应用。该文梳理了近几年该课题组在液体薄层中的超声空化研究中的一些成果,力图揭示液体薄层内空泡、空化云、空化场的运动和分布规律,及其产生、发展和演化过程,以期对液体薄层中的超声空化行为有一个相对清晰和完整的认识。     

基于OPO脉冲激发的血糖光声检测影响因素研究

构建了一套基于侧向模式的光学参数振荡(optical parameter oscillator,OPO)脉冲激光激发-超声传感的血糖光声检测系统,并且将激发波长、激光能量、探测频率和温度等对血糖光声检测的影响,在系统结构上进行了有效融合。然后,以不同浓度的葡萄糖溶液作为测试样品,实验研究了几个因素(激发波长、激光能量、探测频率和温度等)对葡萄糖光声检测和浓度预测的影响。实验得到了不同浓度葡萄糖溶液在不同影响因素条件下的葡萄糖实时光声信号和光声峰峰值,同时,为了得到不同因素对葡萄糖光声值和浓度预测的影响规律,通过线性回归算法建立了葡萄糖光声峰峰值与各因素变化,以及不同因素下光声峰峰值与浓度梯度的映射关系模型。实验和模型预测结果表明：相比1 200和1 300 nm波长而言,1 064 nm波长下的葡萄糖光声峰峰值与浓度梯度模型预测效果最好,模型相关系数达到0.986;葡萄糖光声峰峰值随着脉冲激光输出能量的增大呈线性增大趋势,且葡萄糖浓度预测准确度随着激光输出能量增大有所提高;根据不同探测频率的超声探测器捕获的葡萄糖光声峰峰值与浓度梯度建模效果来看,响应频率为1 MHz的超声探测器相比2.5和10 MHz的超声探测器,在葡萄糖光声信号探测上具有更好的探测效果;最后,实验发现,葡萄糖光声峰峰值随着温度和浓度的增大均呈线性增大趋势,且浓度预测误差随着温度的升高逐渐增大。     

声源分布和超声频率对清洗声场均匀性的优化*

驻波和换能器指向性等影响声场均匀性,造成清洗死角,影响清洗效果。采用COMSOL仿真软件建立了单个换能器位于底部的三维模型,通过染色法实验结果验证模型的有效性。研究了换能器同时位于底部和侧面、多排换能器位于底部时的声场,用声压幅值相对标准差来量化均匀性,发现该两种换能器分布方式能够有效优化声场均匀性。通过调节频率研究频率对声场的影响,进一步优化声场均匀性。对声源分布的确定、频率的选择以满足声场均匀化需求有指导意义。     

基于视觉感知的光谱评估尺度

光谱颜色复现和色度精度是评价光谱重建算法准确的基础。简单而直观的评价指标对颜色复现控制是必不可少。该指标需要同时表征复现颜色的光谱差和色度差。在研究光谱匹配评估的方法基础上,提出基于颜色视觉感知的三种光谱评估指标,通过加权人眼视觉匹配函数,实现颜色光谱差与色度的评估。通过孟塞尔颜色系统的光谱数据,该论文分析与验证三种视觉加权的评估指标的有效性。通过孟塞尔颜色系统数据,这些指标在CIELab均匀色空间中分布均匀而稳定,从而证明加权算法的评估指标是既表征到颜色感知又反映出颜色的光谱相似度。实证结果表明,加权的指标可以实现同时表征实际人眼的颜色感知和颜色光谱差异。基于人眼视觉感知的评估指标解决了颜色的原始光谱和重建光谱的光谱匹配精度的定量评价问题。所提出评价指标通过一个简单而直观的数值实现对复现颜色光谱与色度评估。     

纵振驱动球面弯曲振动超声聚焦系统的聚焦特性*

为了将超声聚焦效应应用于工业加工中的冷却技术中,该文提出一种由夹心式换能器纵向振动驱动球面弯曲振动超声聚焦系统。基于基尔霍夫-亥姆霍兹声场理论分析了由换能器中心面纵向振动和球面弯曲振动组成的复合超声振动条件下的声场聚焦特性,并通过实验进行验证。研究结果表明,该聚焦系统具有显著的聚焦特性,球面弯曲振动将声能汇聚在声场焦区;当声场相位相同时,换能器中心面纵向振动和球面弯曲振动产生的声场在焦区发生叠加,可以进一步提高焦区声压;减小换能器中心面半径和球面曲率半径、增加球面开口半径可以增强复合超声振动的聚焦效果。     

变厚度多边形蜂窝结构的超声C扫描检测方法

为了解决变厚度多边形蜂窝结构超声波检测难和检测效率低的问题,采用了灵敏度补偿和多边形扫查路径规划相结合的超声C扫描方法进行检测。在扫查检测过程中,一是根据构件厚度变化进行灵敏度补偿,消除因厚度变化而引起的超声信号衰减对检测结果的影响;二是根据构件几何形状对此类构件进行多边形扫查路径规划,减少探头的空扫描范围,提高检测效率。试验结果表明:该检测方法能准确、高效地检出变厚度多边形蜂窝结构中的缺陷。     

ITER第一壁实验件的铍-铜连接界面分析

在ITER第一壁实验件的研究中,采用热等静压扩散连接技术对Be与CuCrZr合金进行连接实验,对完成扩散连接的部分连接件采用退火处理。对所有连接件进行超声波无损探伤后,检测到未退火的连接件Be/Cu连接界面存在缺陷。为分析扩散界面缺陷产生原因,从连接件的无缺陷区取样并进行界面微观分析。通过观察微观形貌和分析界面扩散层合金元素的变化,发现退火处理过的Be-Cu扩散界面的Cu-Ti扩散层和未扩散的Ti层厚度增加,中间层中Be与Cu元素形成脆性相的几率降低,整个扩散层厚度变大,扩散范围加大。实验表明退火工艺能改变Be/Cu热等静压扩散层连接结构组成,扩大扩散连接范围。     

Invariant submodels of the Westervelt model with dissipation

We study three-dimensional Westervelt model of nonlinear hydroacoustics with dissipation. We received all its invariant submodels. With the help of invariant solutions, we explored some wave processes, specifying their physical meaning. The boundary value problems describing these processes are reduced to the nonlinear integro-differential equations. We established the existence and uniqueness of the solutions of these boundary value problems under some additional conditions. Also we considered the invariant solutions of rank 2 and 3. Mechanical relevance of the obtained solutions is as follows: (1) these solutions describe nonlinear and diffraction effects in ultrasonic fields of a special kind, (2) these solutions can be used as a test solutions in the numerical calculations performed in studies of ultrasonic fields generated by powerful emitters.