A Note on First-Fit Coloring of Interval Graphs

We apply the Column Construction Method (Varadarajan et al., Proceedings of the Fifteenth Annual ACM-SIAM Symposium On Discrete Algorithms, pp. 562–571, 2004) to a minimal clique cover of an interval graph to obtain a new proof that First-Fit is 8-competitive for online coloring interval graphs. This proof also yields a new discovery that in each minimal clique cover of an interval graph G, there is a clique of size .     

On an online random k‐SAT model

Given n Boolean variables x₁,…,x_n, a k‐clause is a disjunction of k literals, where a literal is a variable or its negation. Suppose random k‐clauses are generated one at a time and an online algorithm accepts or rejects each clause as it is generated. Our goal is to accept as many randomly generated k‐clauses as possible with the condition that it must be possible to satisfy every clause that is accepted. When cn random k‐clauses on n variables are given, a natural online algorithm known as Online‐Lazy accepts an expected (1 ? )cn + a_kn clauses for some constant a_k. If these clauses are given offline, it is possible to do much better, (1 ? )cn + Ω( )n can be accepted whp . The question of closing the gap between a_k and Ω( ) for the online version remained open. This article shows that for any k ≥ 1, any online algorithm will accept less than (1 ? )cn + (ln 2)n k‐clauses whp , closing the gap between the constant and Ω( ). Furthermore we show that this bound is asymptotically tight as k → ∞. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008     

Online UV–visible spectroscopy and multivariate curve resolution as powerful tool for model-free investigation of laccase-catalysed oxidation

The laccase-catalysed transformation of indigo carmine (IC) with and without a redox active mediator was studied using online UV–visible spectroscopy. Deconvolution of the mixture spectra obtained during the reaction was performed on a model-free basis using multivariate curve resolution (MCR). Thereby, the time courses of educts, products, and reaction intermediates involved in the transformation were reconstructed without prior mechanistic assumptions. Furthermore, the spectral signature of a reactive intermediate which could not have been detected by a classical hard-modelling approach was extracted from the chemometric analysis. The findings suggest that the combined use of UV–visible spectroscopy and MCR may lead to unexpectedly deep mechanistic evidence otherwise buried in the experimental data. Thus, although rather an unspecific method, UV–visible spectroscopy can prove useful in the monitoring of chemical reactions when combined with MCR. This offers a wide range of chemists a cheap and readily available, highly sensitive tool for chemical reaction online monitoring.     

专家控制技术在船舶机舱监测报警系统中的应用研究

为提高船舶自动化程度,实现无人机舱,将专家控制技术应用到机舱监测报警系统中;详细阐述了专家控制系统的结构、原理,从受控对象、专家控制器、规则库、推理机四方面介绍了建模过程;并结合结构功能、知识表示、传感数据预处理完成了智能机舱监测报警系统的建立;最后通过大连海事大学开发的DMS-2015轮机模拟器对专家控制型机舱监测报警系统进行了验证,结果表明,该系统的应用,使机舱故障报警更加精确,故障排除更加方便,大大降低了轮机员工作值班的疲劳强度,而且为船舶机舱监测报警提供了一个新思路。     

双余度发动机状态监测技术的研究与应用

在飞机、舰艇、装甲、汽车电子控制系统中采用双余度发动机状态监测技术,能够有效提高飞机、舰艇、装甲、汽车运行的安全性和可靠性,以某型涡轴发动机为研究对象,对双余度发动机状态监测技术进行了深入研究,研制了双余度发动机状态监测系统,介绍了系统的总体设计、软硬件设计、余度设计,虚拟仪表设计,并在双余度发动机状态监测系统的设计中引入了嵌入式PC/104模块;为了使状态监测系统具有更好的扩展性和适应性,将系统设计成可以在两种方式下工作:机载运行方式和地面试车方式,通过这两种方式对发动机状态进行自动监测,为发动机的状态趋势分析、故障诊断和视情维修提供科学的依据;采用双余度发动机状态监测技术研制的某型涡轴发动机状态实时监测系统经过了大量的地面试验和某型直升机上试飞试验,功能、性能满足要求,目前该系统已在某型直升机上得到应用。     

Triple‐pulse Method for Monitoring Formate in CO2 Conversion Process

In CO₂‐to‐formic‐acid process, real‐time monitoring of formate is pivotal for the efficient control of the process. A stable sensing method that is suitable for measuring the high concentrations of formate produced during this process is required. Here, we developed a triple‐potential‐step method to monitor the formate in the range of 0.1 to 2.0 M and showed that a long‐term, continuous monitoring is possible. Among the Pd‐, Pt‐, and Au‐electrode materials tested, Au was the best option due to its low sensitivity and its stability in formate oxidation.     

Separation and determination of diversiform phytosterols in food materials using supercritical carbon dioxide extraction and ultraperformance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry

This paper presents at first time that the ultra-performance™ liquid chromatographic atmospheric pressure chemical ionization mass spectrometer (UPLC-APCI-MS) was used as an efficient method for the identification and quantification of diversiform phytosterols in food materials. The sample preparation consisted of extraction by supercritical carbon dioxide fluid extraction (SCE) and saponification by refluxing with ethanolic KOH, and then the non-saponificable fraction was extracted with petroleum ether. This fraction was subjected to solid phase extraction (SPE) on silica gel cartridge and then the sterols were eluted with hexane-ethyl acetate. Sterols were separated on an Acquity UPLC™ BEH C18 column (100 mm × 1.0 mm, 1.7 μm particle size) with a gradient of methanol/water (1% acetonitrile) at a flow of 0.1 mL min⁻¹. The determination was performed in selective ion monitoring mode. The quality parameter of the developed method was established using 6-ketocholestanol as internal standard. Limits of quantification (LOQ) were 0.1754, 0.0341, 0.0500, 0.0205, 0.0225, 0.3674, 0.0241, 0.0272, 0.0076 μg L⁻¹ and 0.1525 μg mL⁻¹ for 6-ketocholestanol, desmosterol, ergosterol, cholesterol, lanosterol, cholestanol, campesterol, stigmasterol, β-sitosterol, and stigmastanol, respectively. The intra- and inter-day determination precision for the 10 phytosterols were less than 5 and 6% in relative standard deviations, and their recoveries were located in the range of 94-107%. The developed approach has been applied successfully for efficient determination of diversiform phytosterols in food materials, including corn, sesame, oat and peanut.     

线上教学的难题与解决方法*——大学化学慕课建设中的思考

利用中国大学 MOOC平台进行“大学化学”慕课的第二次录制。在本次课程的建设中,总结第一次录制时遇到的线上教学难题,提出“私人定制,以学为本,冲击高阶,求实创新”的新目标,开展分层递进等教学模式。实践表明,该模式可以满足不同基础学生的需求,大幅提高学习效率,克服线上教学学生基础差距大、教学效果反馈不及时等难题;同时兼具科普和思政教育效果。     

Molecular imprinted membrane biosensor for pesticide detection: Perspectives and challenges

Polymers are crucial component for modern sensor devices. However, comprehensive research on polymer sensor technology is still going strong. Molecular imprinted membrane (MIM) is a great design that demonstrates acceptable recognition ability when integrated with a sensing transducer. Generally, the detection technique that has been widely and sparingly used for pesticide is mass spectrometry merged with gas and/or liquid chromatography. Nevertheless, this review focuses not on these common methods but on the specific methodology of MIM biosensor for the analysis of pesticides. Finally, the transduction schemes of the MIM sensor are reviewed. The interest of this article is sketched to the trends and challenges present in this field of study.