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关键词： 无损检测   阻抗   交变电场   频率曲线  

摘要： 在相同条件下,通过不同大小、不同成熟度果实的阻抗不同的特点,设计出一种更加直观方便快捷地判断果实成熟度并实现果实分级的方法及仪器。无损检测是一种非破坏性的检测方法,它利用物理学方法(如力学、光学、声学等)对样品内部进行品质评估,而不需要破坏样品。这种方法主要通过适当频率的交变电场来检测果实的阻抗特性参数,这些参数会随着频率的变化而按一定的规律变化。如果果实成熟度不同,那么果实的阻抗频率曲线也会不同。通过观察这些曲线,可以了解到果实的阻抗频率特性。

关键词： 地下连续墙   水平位移   密集分布式感测   数值模拟   临界厚度比  

摘要： 地下连续墙是一种常见的深基坑支护方式,具有刚度大、防渗性能好、适应范围广等优点,但其受力变形规律较为复杂。基于超弱光纤光栅感测技术,对某地铁车站基坑地下连续墙水平位移进行实时监测。将监测数据与数值模拟结果进行对比,验证了数值分析模型选取的合理性,并基于该数值分析模型研究了不同厚度软土层中,地下连续墙水平位移的变化规律,通过墙体位移梯度(D_(w))和软土位移梯度(D_(r))进行临界厚度比计算。研究结果显示:水平位移随软土厚度的变化呈“凸肚”状,沿深度方向划分为相对稳定区、线性增长区、最大变形区和线性下降区。利用D_(w)和D_(r)标定出临界厚度比为0.24;土压力变化在基坑前四步开挖过程中较为稳定,而在第五步开挖与施工后40 d变化显著。上述研究结果为类似工程的设计、施工和监测方案的制定提供了重要参考。

关键词： 大电流测量   塑壳断路器   光纤电流传感器   现场校准  

摘要： 针对塑壳断路器可靠性试验电流的大幅值、短时、交直流混合等特点以及现场复杂工况对大电流标准传感器的严苛要求,提出了基于光纤电流传感技术的塑壳断路器可靠性试验电源现场校准方法。根据光纤电流传感器的闭环检测原理建立了系统的动态模型,分析了阶跃响应和频率响应特性,仿真结果表明:通过调节系统的前向增益及滑动滤波器阶数,传感器的上升时间优于9.09μs,-3 dB带宽可达39.91 kHz,证明了光纤电流传感器对塑壳断路器可靠性试验电流的跟踪响应能力。基于等安匝法对光纤电流传感器进行校准,评定了校准结果的不确定度,结果表明:在2.5~60 kA范围内,传感器的直流、工频电流测量准确度优于0.2%。对塑壳断路器可靠性试验电流进行了现场测试,为塑壳断路器可靠性试验电源的现场校准提供了一条技术途径。

关键词： 熔融度   熔锥型光纤耦合器   特性影响   光纤通信  

摘要： 熔锥型光纤耦合器是一种重要的光无源器件,在光纤通信、光学传感等领域有着广泛应用。通过实验的方法,深入研究熔融度对光纤耦合器耦合效率、光学性能和机械稳定性的影响。通过调整加热温度和熔融时间等参数,控制光纤材料的熔融程度。在光纤熔融拉锥过程中,采用不同的加热方式和熔融工艺,以获得不同熔融度的光纤耦合器,发现熔融度对耦合效率、光学性能和机械稳定性有重要影响。研究结果为进一步优化熔锥型光纤耦合器的设计和性能提供了重要指导,对促进光纤通信和光学传感技术的发展具有重要意义。

关键词： 微电子机械系统   风速风向传感器   热式   倾斜效应  

摘要： 主要针对智能电网、海上浮标等容易发生倾斜状态的应用场景,研究了微电子机械系统(MEMS)热式风速风向传感器的输出性能,并对带有空气动力学壳罩的传感器进行了有限元仿真和风场测试。测试结果表明,风向测量误差和仿真误差均较小,但风速测量误差却远大于仿真误差。进一步分析可知,其原因是传感器在封装时其外壳容易产生倾斜。为了解决这一问题,采用3D打印技术实现一体化的封装外壳。测试结果表明,在±20°以内的倾斜状态下,优化后传感器的风速、风向测量误差分别满足±(0.3+5%v)m/s、±3°的指标要求。

关键词： 副溶血弧菌   即时检测   环介导等温扩增   电化学检测   便携设备  

摘要： 为满足现场检测海产品中的副溶血弧菌(Vibrio parahaemolyticus)的需求,本文建立了一种基于电化学检测和环介导等温扩增方法的副溶血弧菌现场检测系统,设备核心电路的尺寸仅为7 cm×4 cm,质量为30 g,易于携带,可以在30 min内出检测结果,且可以对样本中的副溶血弧菌进行定量分析,检测限可达103 CFU/mL。同时,利用该系统对加标虾样品中副溶血弧菌进行检测,检测限低至3.6×103 CFU/g。随着核酸扩增反应的进行,核酸扩增体系的pH降低,本文制备的pH敏感电极可以实时监测核酸扩增体系的pH微量变化,精度为0.016个pH单位,本系统的检测限与荧光检测的检测限一致。本系统具有便携、快速、特异性好、灵敏度高、成本低、可现场检测等优点,本研究有利于食品安全中分子诊断技术的基层下沉,满足公共卫生安全的战略需求。

关键词： 桥梁与隧道工程   钢桥面板   贯穿型裂纹   穿透法   超声波检测  

摘要： 目的 提出一种基于超声波透射信号的钢桥面板贯穿型裂纹检测方法,提高在役钢桥隐蔽裂纹检测精度和效率。方法 采用数值分析方法研究了超声波在含裂纹面板中的传播机制,分析了不同裂纹参数与接收信号强度的变化规律,并通过顶板贯穿裂纹检测试验,进一步验证该检测方法的可行性。结果 裂纹检测参数建议激励晶片边长为4 mm、激励频率为5 MHz、K值为0.8;裂纹宽度小于0.1 mm时可忽略裂纹宽度对检出信号的影响,裂纹宽度大于0.1 mm时可将尖端反射信号作为判断依据;透射信号与裂纹深度呈负相关,恢复至最大值时的入射坐标与裂纹深度呈线性关系,作为裂纹深度的计算依据,检测误差在1 mm以内。结论 基于穿透信号的超声波检测方法,以恢复至最大值时的入射坐标为主要指标,可以实现钢桥顶板贯穿裂纹的有效检测。

关键词： Electro-Fenton   Photo electro-Fenton   Imidacloprid   Degradation   RSM-CCD   Wastewater treatment   PHOTOELECTRO-FENTON   ANODIC-OXIDATION   ELECTROCHEMICAL DEGRADATION   AQUEOUS-SOLUTIONS   TOXICITY   MINERALIZATION   PESTICIDES   GENERATION   PARAMETERS   SULFATE  

摘要： This study aims to investigate the removal efficiency of insecticide imidacloprid (IMD) from its commercial formulation using electro-Fenton (EF) and photo electro-Fenton (PEF) processes in an open undivided electrolytic cell (BDD/Carbon felt). Ferrous (Fe2+) was used as catalyst in sulfate medium (Na2SO4) for both processes and a UV-C lamp (7 W) was used in PEF as source of UV irradiation. The effect of various operating conditions on IMD and COD removal was studied based on the response surface methodology (RSM-CCD). Optimal conditions for achieving maximum removal of IMD and COD by EF have been determined as follows: 17.15 mA cm- 2 of current density, 0.255 mM of [Fe2+], and an electrolysis time of 80 min and 120 min for IMD and COD removals, respectively. The PEF process has been identified as a more efficient process compared to EF. It achieved 98 % of IMD removal after 75 min and 97 % of COD removal after 4 h of electrolysis time, with a Mineralization Current Efficiency (MCE%) value of 28.87 % and an Energy Consumption (EC) value of 7.9 kWh kg- 1 COD removed in 3 h. Furthermore, quenching experiments using methanol, 2-propanol, and tert-butanol as scavengers indicated that the primary oxidizing agent responsible for IMD degradation is center dot OH/BDD(center dot OH).

关键词： Water purification   Adsorption   GO-Ag   RSM-CCD   Chloride ion   LAYERED DOUBLE HYDROXIDES   ADSORPTION   NANOFLUID   EFFICIENT   ISOTHERM  

摘要： Chloride (Cl-) is one of the pollutants that can cause significant health risks when its concentration is high in drinking water. Utilizing adsorption has a superiority in removing pollutants from water due to their large active surface area, small volume, and high adsorption capacity. Herin, graphene oxide (GO) modified with AgNO3 was used for Cl- removal. FESEM, EDAX, FTIR, zeta potential (zeta), and XRD analysis were employed for the char-acterization of synthesized adsorbent. The maximum Cl- removal (99.24 %) was achieved under optimized conditions by RSM based on CCD method (adsorbent dosage: 2 g/L, Cl- concentration: 30 mg/L, and reaction time: 17 min). The models of Langmuir and Freundlich isotherms were employed to determine the adsorption process. It was found that the Langmuir isotherm model with an R2 value of 0.9987 described the Cl-removal process appropriately. Finally, a comparison between the adsorbent's performance before and after modification with AgNO3 was made, demonstrating that the modified absorbent provided 87 % better efficiency than the unmodified adsorbent in the case of Cl-removal.

关键词： Response surface methodology   Gum Arabic   Polysulfone   Zinc oxide nanoparticles   Biosynthesis   ULTRAFILTRATION MEMBRANE   PHASE INVERSION   OPTIMIZATION   REMOVAL   PURIFICATION   FABRICATION   POLYMER   DESIGN   DYE  

摘要： Response surface methodology (RSM) was used to find the best ratio in preparing the polysulfone (PSf) ultrafiltration (UF) membranes via phase inversion. The central composite design was used to make predictive regression models and study the effects of different parameters, such as the concentration of PSf polymer, the concentration of gum Arabic (GA), and the content of biosynthesized zinc oxide nanoparticles, on water flux, rejection, and porosity. Twenty tests were done to build a quadratic model, and the membranes were evaluated with scanning electron microscopy (SEM), atomic force microscopy (AFM), and water contact angle measurements. Using a Lab-scale cross-flow filtering device, performance testing was undertaken. The variance analysis showed that all three independent parameters were statistically important, and the model made from them was pretty good. To explain the regression equations, response surfaces, and outlines were plotted. The best experimental conditions were evaluated for water permeation flux, rejection, and porosity. The best parameters led to a maximum permeation flow of 381.5 L m-2 h-1, a rejection of 54%, and a porosity of 85.1%. With R2 values of more than 90%, the correlation between the measured and predicted values of pure water flux, rejection, and porosity values of the membranes validates the model's correctness.