Insights into discrepancy in power generation among glucose and malate grown Rubrivivax benzoatilyticus JA2 microbial fuel cells

In this study, Rubrivivax benzoatilyticus JA2^T (=ATCC BAA-35^T = JCM 13220^T = MTCC 7087^T), an anoxygenic photosynthetic bacterium, was subjected to altered conditions and observed for changes in power outcome in the two chambered microbial fuel cells (MFCs), the basis of which was established using metabolomic studies. This is an extension to our previous studies, which showed that, under photo heterotrophic conditions, glucose in the form of a solitary carbon resource in minimal media, caused the strain JA2 to exhibit altered growth rates, progressive loss of pigmentation and reduced cell size (3–4 μm), compared to malate grown cells (6–7 μm). When R. benzoatilyticus JA2 cells were grown in malate bio-anodes, they presented higher potentials (289.22 ± 4.6 mV or 436.22 OCV per mg dry weight) compared to glucose bioanodes (163 ± 5.5 mv or 188.98 OCV per mg dry weight). Insights from the metabolomic footprints and fingerprints have revealed differential regulation of key components in the central metabolic pathway such as fumarate, citrate and succinate, which are significantly increased in malate grown bio anodes. Strain JA2 cells when grown with malate as substrate are densely grown on the electrodes and exhibited reduced size, when observed under SEM, which contrasts with control cells grown on malate broth. The artificial selection pressure of the MFC and the different metabolic pathways followed by these bacteria are the reasons for such discrepancy in the power production by the strain JA2. These adaptations may indicate survival advantage during the electron transfer and growth in bio anodes. The study throws light on what types of effluents would be more suitable as substrates for R. benzoatilyticus JA2 microbial fuel cells.     

Adsorption and inhibition behavior of a novel Schiff base on carbon steel corrosion in acid media

In this study, the inhibition effect of 2,2′-(heptane-1,7-diylbis(azanylylidene)bis-(methanylylidene))diphenol (HAMD) on carbon steel corrosion in 0.5 mol L⁻¹ H₂SO₄ solution was studied. Weight loss and electrochemical techniques such as open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to inspect the efficiency of HAMD as corrosion inhibitor. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDAX) were used to characterize the steel surface. Polarization measurements indicated that, the studied inhibitor acts as mixed-type inhibitor. The adsorption of HAMD molecules on the carbon steel surface obeys Langmuir adsorption isotherm.     

采用ER阻尼器作斜拉索半主动振动控制的试验研究

提出了基于ER/MR阻尼器的半主动控制算法对斜拉索进行振动控制,并进行了振动控制试验。该算法建立在离散时间系统的基础上,并考虑了EP/MR阻尼器的力学特性而发展起来的,因此具有很大的应用价值。首先通过模态降阶的理论,减少了系统的自由度数目,使系统更易于控制。在阻尼器采用Bingham模型的半主动控制策略的基础上,应用更符合阻尼器实际力学特性的双粘性模型,提出了相应的改进办法。然后在试验室建立了缩尺比为1∶12的一根12m长的斜拉索试验模型,考虑到ER阻尼器与MR阻尼器具有相似的力学特性,选用ER阻尼器作为作动器,完成了斜拉索半主动振动控制的试验研究,并与理论结果进行了比较,两者吻合良好。     

大功率机电静压伺服机构动态特性研究

针对大功率机电静压伺服机构在摇摆未来火箭发动机中的潜在应用,研究了其高动态实现的技术途径。结果表明,相对于大惯量摇摆发动机自身偏低的结构固有频率,泵控液压作动器可以有足够高的液压固有频率。采用结构一体化的伺服电机泵和伺服机构本体设计,可以消除传统连接导管等对液压固有频率的负面影响,结合成熟的伺服电机驱动控制技术,可以实现满意的频宽。通过进行理论仿真分析、样机设计制造和试验研究,在1000 kg·m2大惯量模拟负载条件下,输入5%满幅值指令时,10 kW级别样机的-3 dB幅频带宽达71.2 rad/s,-45°相频带宽达18.5 rad/s,且负载谐振抑制性能良好。由此可见,机电静压伺服机构具备应用于火箭摇摆发动机之类的大功率场合的高动态能力。     

机电液系统转速波动分量Vold-Kalman时变滤波提取方法

机电液系统的转速波动信号蕴含着丰富的系统运行状态信息,从该转速波动信号中通常可以观测到多个波动源的耦合现象。针对磁电式转速传感器输出的方波信号中转速波动分量的特征提取问题,提出了基于Vold-Kalman时变滤波的转速波动分量提取方法。首先利用采样点计数测速算法获得变转速泵控液压马达系统的瞬时转速信号;其次,结合短时傅立叶变换和二值细化处理得到的瞬时频率估计曲线作为中心频率,构造了基于转速波动信号特征模型的结构方程和数据方程;最后通过最小二乘滤波和PCG法求解,实现了转速波动分量时域波形的提取。实验结果表明:该方法能有效地提取变转速泵控马达系统中由柱塞马达输出轴转频及减速箱输出轴转频引起的转速波动,为机电液系统的状态监测和运行可靠性分析提供了新方法。     

双履带机器人电液行走控制系统建模与仿真

根据光伏板清扫机器人作业工况特点,提出了一种全液压履带式双阀控双马达驱动系统方案。为满足机器人直线行驶需求,提出双通道等同式交叉耦合同步控制策略,并建立阀控双马达同步控制系统数学模型。利用仿真工具Simulink对原设计系统模型和PID矫正后系统的动态特性性能进行仿真分析。仿真结果表明:校正后系统响应速度和稳定精度得到改善,经校正后,该系统能较好地满足清扫机器人工况要求。     

A universal method to fabricate Cu films with superhydrophobic and anti-corrosion properties

Multi-functional Cu films were fabricated by an improved electric brush-plating technique and subsequent immersion treatment in ethanol solution of stearic acid. The brush-plated Cu film exhibited unique lotus-like surface architectures, which endowed it with highly hydrophobicity, instead of metallic intrinsic hydrophilicity. After solution-immersion for certain time, the Cu films were gradually covered by a continuous net-like layer of copper stearate nano-sheets with low surface energy, which finally rendered them stable superhydrophobic and even self-cleaning. Electrochemical measurement revealed that anti-corrosion property of Cu is intimately linked with its surface wettability, and the superhydrophobicity indeed provides high corrosion resistance for Cu substrate in corrosion environment. This strategy can extend generally to other relevant metals.     

摊铺机行走监控系统研制

为提高路面摊铺平整度、初始密实度,研制了一种基于CAN总线的摊铺机行走监控系统.该系统以C8051F040芯片为主控制器,采用模糊PID控制策略和CAN总线通讯技术,实现了摊铺机的实时监控和恒速控制.系统硬件和软件分别采用电磁兼容保护和抗干扰措施,通过了严酷的工业环境级别的电快速脉冲群试验.现场应用表明,该行走监控系统操作简单,具有智能化和可靠性等优点.     

Gas sensing of colloidal polyaniline in a chemoresistor consisting of nanometer electrodes

The high conductivity of colloid-conducting polymers is explained by the networking structures and the hopping mechanisms of the metallic particles [1], [2] and [4]. To observe how the metallic region and the networking structures differ in sensing NH₃ gas, E-beam lithography and electromigration were used to make chemoresistors with nanometer-gap electrodes. Colloid Pani was coated on a nanometer gap as a reaction matrix for the gas. The I-V curves were measured in a vacuum and the NH₃ gas was nonlinear. In sensors with a gap of less than 10 nm, there was a two- or threefold increase in the conductivity, and the work function decreased from 600 meV in a vacuum to 250 meV in NH₃ gas. In contrast, the conductivity of sensors with gaps of 200 and 500 nm decreased to 1/1000 in the NH₃ gas environment. The decrease of the conductivity can be explained by electron-hole annihilation, which appears to occur on the surface of the secondary particles. With comb-type electrodes, the operating voltage can be decreased by three orders of magnitude. In electrodes with 200 and 500 nm gaps, the I-V has a step-type response to NH₃ gas.