Active disturbance rejection based trajectory linearization control for hypersonic reentry vehicle with bounded uncertainties

This paper investigates a novel compound control scheme combined with the advantages of trajectory linearization control (TLC) and alternative active disturbance rejection control (ADRC) for hypersonic reentry vehicle (HRV) attitude tracking system with bounded uncertainties. Firstly, in order to overcome actuator saturation problem, nonlinear tracking differentiator (TD) is applied in the attitude loop to achieve fewer control consumption. Then, linear extended state observers (LESO) are constructed to estimate the uncertainties acting on the LTV system in the attitude and angular rate loop. In addition, feedback linearization (FL) based controllers are designed using estimates of uncertainties generated by LESO in each loop, which enable the tracking error for closed-loop system in the presence of large uncertainties to converge to the residual set of the origin asymptotically. Finally, the compound controllers are derived by integrating with the nominal controller for open-loop nonlinear system and FL based controller. Also, comparisons and simulation results are presented to illustrate the effectiveness of the control strategy.     

伺服系统位置反馈采集电路误差分析

针对伺服系统位置反馈采集电路硬件的筛选要求,确定采集电路对典型电压值的采集误差范围,在批量生产中尽早剔除有硬件缺陷的产品。位置反馈采集电路主要由运放跟随电路、模数转换电路、电压基准电路等模块组成。分别计算各个模块引入的最大采集理论误差,综合测试设备的测试误差得到系统对典型电压+2.5 V最大采集误差为25 LSB。最后,举例说明在电路板交付中,该筛选方法可以成功剔除硬件故障产品,测试误差范围有效,能有效地避免故障件流入后续装配工段。     

Multi-walled carbon nanotubes-based magnetic solid-phase extraction for the determination of zearalenone and its derivatives in maize by ultra-high performance liquid chromatography-tandem mass spectrometry

A simple and rapid magnetic solid-phase extraction (M-SPE) procedure using multi-walled carbon nanotube-magnetic nanoparticles (MWCNT-MNPs) as sorbents was established for purification of zearalenone (ZEA), α-zearalenol (α-ZOL), β-zearalenol (β-ZOL), zearalanone (ZAN), α-zearalanol (α-ZAL) and β-zearalanol (β-ZAL) in maize. The main parameters affecting the clean-up efficiency were thoroughly investigated, and high purification efficiencies for all analytes were obtained. The resulting MWCNT-MNP-ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was validated for maize samples. The matrix effects were greatly minimized using the M-SPE approach, with signal suppression/enhancement values decreased from 69.9–127.6% to 92.1–103.8%. Consequently, complex matrix-matched calibration curves were not necessary and the calibrations constructed in acetonitrile could be applied for accurate quantification of the targeted mycotoxins in real samples. The average recoveries ranged from 75.8 to 104.1% and the inter- and intra-day precision values expressed as RSDs, were all lower than 14%. Limits of detection and quantification were in the range of 0.03–0.04 and 0.07–0.10 μg/kg, respectively. The analytical performance of the developed method was also successfully evaluated with maize samples, and this method was proved to be a powerful tool for monitoring ZEA and its derivatives in maize.     

TLC/FID分析原油SARA组成方法研究

以渤海原油为研究对象,建立原油棒状薄层色谱／氢火焰离子化检测器（TLC／FID）族组分分析方法,对原油的四个族组分（饱和烃、芳烃、胶质、沥青,SARA）进行了分析。并对其影响因素展开次数、点样量、展开剂的干燥方式进行了优化,在优化所得条件下,方法的精密度RSD值为3．54％,方法重现性RSD值为3．23％。与文献报道方法相比,本文建立的方法,可将原油中的胶质和沥青两个组分分开,更能全面反应原油的族组成成分,具有分析速度快、有机溶剂用量少、操作简单等特点。最后将建立的方法应用到不同来源的原油中,结果令人满意。     

人参柔顺洗发水中人参皂苷的鉴别和含量测定

建立了人参柔顺洗发水中人参皂苷Rg1,Re和Rb1的鉴别和含量测定方法.采用薄层色谱(TLC)法,以氯仿-甲醇-水(体积比2∶1∶0.1)为展开溶剂,对人参皂苷进行鉴别;通过高效液相色谱(HPLC)法,以乙腈-水为流动相梯度洗脱,测定洗发水中人参皂苷的含量.结果显示TLC法能同时鉴别人参皂苷Rg1,Re和Rb1;HPLC法中人参皂苷Rg1,Re和Rb1的线性回归方程分别为Rg1∶y=246 683x -7 070.6,r=0.999 9;Re∶y=388 224x - 11 320,r=0.999 9;Rb1∶y=216 383x+3 644.9,r=0.999 9;平均回收率分别为99.69％,97.39％和98.05％,RSD值分别为1.62％,1.75％和0.68％.     

SELECTIVE OXIDATION OF ALCOHOLS BY REDOX MOLECULAR SIEVES

High-throughput synthesis and screening of libraries consisting of redox zeolites and molecular sieves have been developed for the selective oxidation of 2-butyl-5-hydroxymethyl-imidazole to the corresponding aldehyde in the liquid phase. Libraries consisting of 96 catalysts were prepared and screened for catalytic activity using high-throughput software, robotics, reactor, and screening technologies. The integrated synthesis and screening workflow allowed ～5000 samples to be screened in less than one month. Promising hits identified in the high-throughput primary screens were successfully scaled up and optimized in conventional laboratory test units. Best results have been obtained with doubly or triply doped mesoporous sieves containing both an impregnated and framework-substituted metal. PtBi-doped framework-substituted V-MCM-41 redox mesoporous sieves were found to be efficient catalysts for aerobic oxidation under relatively mild reaction conditions (100–150°C, 15–400 psi air, 4–10 h reaction time). MIBK/H₂O/t-BuOH mixtures were identified as efficient solvent systems for this reaction. Isolated yields confirm high selectivities of more than 90% with quantitative conversions. Spent catalysts were shown to be fully regenerable by high temperature calcination in air.     

关于TLC／FID法测定误差的探讨

ＴＬＣ／ＦＩＤ法分析重质油中的烃族组成，具有灵敏、快速、用样量少的优点；但过去一直存在着与经典柱色谱法所测数据可比性差的致命缺点。为此，从ＴＬＣ分离及ＦＩＤ检测的基本原理出发，寻找合适的操作条件，使两种方法具有良好的相关性，完成了ＴＬＣ／ＦＩＤ法由半定量向定量分析的转变。欲减少误差，提高准确度，关键是要做好以下几点：①严格控制点样量，以保证数据重复性；②选择适宜的ＴＬＣ展开条件，以保证被测定物质各     

Identification of phenolic compounds in edible aroids

The objective of these experiments was to study the phenolic compounds present in the cormels of the edible aroids, Colocasia spp and Xanthosoma spp. This investigation shows the existence of a range of phenolic compounds which includes gallic acid, chlorogenic acid, ( + )-catechin, ( ? )-epicatechin and ( ? )-epigallocatechin and the possible presence of proanthocyanidins and jlavonols. Aqueous acetone extracts were examined by thin layer chromatography and high performance liquid chromatography for their phenolic constituents.     

Identification of flavonol glycosides in American cranberry fruit

Two flavonol glycosides, quercetin galactoside and quercetin arabinoside, have been identified in American cranberry fruit, as a complementary investigation of our previous study. The analysis processes included separation, hydrolysis and structure elucidation of flavonol glycosides. The separation of flavonol glycosides was carried out by solvent extraction, thin-layer chromatography (TLC) and high performance liquid chromatography (HPLC). After hydrolysis of the obtained flavonol glycosides, flavonol aglycones and sugars were identified by HPLC and gas chromatography–mass spectrometry (GC–MS), respectively.