A blast furnace fault monitoring algorithm with low false alarm rate:Ensemble of greedy dynamic principal component analysis-Gaussian mixture model

The large blast furnace is essential equipment in the process of iron and steel manufacturing. Due to the complex operation process and frequent fluctuations of variables, conventional monitoring methods often bring false alarms. To address the above problem, an ensemble of greedy dynamic principal component analysis-Gaussian mixture model(EGDPCA-GMM) is proposed in this paper. First, PCA-GMM is introduced to deal with the collinearity and the non-Gaussian distribution of blast furnace data.Second, in order to explain the dynamics of data, the greedy algorithm is used to determine the extended variables and their corresponding time lags, so as to avoid introducing unnecessary noise. Then the bagging ensemble is adopted to cooperate with greedy extension to eliminate the randomness brought by the greedy algorithm and further reduce the false alarm rate(FAR) of monitoring results. Finally, the algorithm is applied to the blast furnace of a large iron and steel group in South China to verify performance.Compared with the basic algorithms, the proposed method achieves lowest FAR, while keeping missed alarm rate(MAR) remain stable.

Surface Analysis of Chemical Stripping Titanium Alloy Oxide Films

The chemical stripping method of titanium alloy oxide films was studied. An environment friendly solution hydrogen peroxide and sodium hydroxide without hydrofluoric acid or fluoride were used to strip the oxide films. The morphologies of the surface and cross-section of the oxide films before and after the films stripping were characterized by using scanning electron microscopy （SEM）. The microstructure and chemical compositions of the oxide films before and after the films stripping were investigated by using Raman spectroscopy （Raman） and X-ray photoelectron spectroscopy （XPS）. It was shown that the thickness of the oxide film was in the range of 5-6 μm. The oxide films were stripped for 2 to 8 min in the solution. Moreover, the effect of the stripping time on the efficiency of the film stripping was investigated, and the optimum stripping time was between 6-8 min. When the stripping solution completely dissolved the whole film, the α/β microstructure of the titanium alloy Ti-10V-2Fe-3Al was partly revealed. The stripping mechanism was discussed in terms of the dissolution of film delamination. The hydrogen peroxide had a significant effect on the dissolution of the titanium alloy anodic oxide film. The feasibility of the dissolution reaction also was evaluated.

Dimensionality Reduction with Input Training Neural Network and Its Application in Chemical Process Modelling

Many applications of principal component analysis (PCA) can be found in dimensionality reduction. But linear PCA method is not well suitable for nonlinear chemical processes. A new PCA method based on im-proved input training neural network (IT-NN) is proposed for the nonlinear system modelling in this paper. Mo-mentum factor and adaptive learning rate are introduced into learning algorithm to improve the training speed of IT-NN. Contrasting to the auto-associative neural network (ANN), IT-NN has less hidden layers and higher training speed. The effectiveness is illustrated through a comparison of IT-NN with linear PCA and ANN with experiments. Moreover, the IT-NN is combined with RBF neural network (RBF-NN) to model the yields of ethylene and propyl-ene in the naphtha pyrolysis system. From the illustrative example and practical application, IT-NN combined with RBF-NN is an effective method of nonlinear chemical process modelling.

Synthesis and Characterization of Pr(DPM)_3 Served as Precursor for MOCVD

Praseodymium β-diketone chelate, Pr （DPM）3 [ DPM = 2,2,6,6 -tetramethyl-3,5-heptanedionato ], was successfully synthesized from the inorganic salt praseodymium chloride and HDPM（2,2,6,6-tetramethyl-3,5-heptane-dione） in an ethanol/aqueous solution followed distillation at low pressure and recrystallization from toluene. The physical and thermal properties of the chelate, including volatility, stability, and thermal decomposition, were investigated by elemental analyses, 1^H NMR spectroscopy, XRD, TG/DTG/DTA analysis, infrared spectroscopy, and mass spectroscopy. The chelate with high purity prepared by the authors of this study also shows sufficient volatility and Stability in inert gases, which could be used as the precursor for metal-organic chemical vapor deposition（MOCVD）.

Probabilistic Approach to Risk Analysis of Chemical Spills at Sea

Risk analysis of chemical spills at sea and their consequences for sea environment are discussed. Mutual interactions between the process of the sea accident initiating events, the process of the sea environment threats, and the process of the sea environment degradation are investigated. To describe these three particular processes, the separate semi-Markov models are built. Furthermore, these models are jointed into one general model of these processes interactions. Moreover, some comments on the method for statistical identification of the considered models are proposed.

Synthesis, Crystal Structure and Characterization of a New Dihydrogenomonophosphate: (C₇H₉N₂O)H₂PO₄

Chemical preparation, X-ray single-crystal, thermal behavior, and IR spectroscopy investigations are given for a new organic cation dihydrogenomonophosphate (C7H9N2O)H2PO4 (denoted ABHP) in the solid state. This compound crystallizes in the monoclinic space group P21/n. The unit cell dimensions are: a = 11.011(5) &Aring, b = 5.861(1) &Aring, c = 15.944(4) &Aring and β = 100.81(5) with V = 1010.7(6) &Aring3 and Z = 4. The structure has been solved using direct method and refined to a reliability R factor of 0.048. The atomic arrangement can be described as inorganic clusters [H4P2O8]2- anions between which are located the organic dimmers (C14H18N4O2)2+ through multiple hydrogen bonds (Figure 1)

Facile Synthesis and Thermal Stability of Nanocrystalline Molybdenum Carbide

Nanocrystalline molybdenum carbide (Mo2C) was prepared via one simple route by the reaction of metallic magnesium powders with molybdenum trioxide and potassium acetate in an autoclave at the condition of 600℃ and 4 h. X-ray powder diffraction (XRD) pattern indicated that the product was hexagonal α-Mo2C, and the cell constant was a = 3.0091 ?, c = 4.7368 ?. Scanning electron microscopy (SEM) image showed that the sample consisted of particles with an average size of about 100 nm in diameter. The product was also studied by the thermogravimetric analysis (TGA). It had good thermal stability and oxidation resistance below 450℃ in air.

On the Regression-Tensor Analysis of the Hardening Process of Metal Coatings

This paper constructs and studies a nonlinear multivariate regression-tensor model for substantiation of necessary/sufficient conditions of optimization of technological calculation of multifactor physical and chemical process of hardening of complex composite media for metal coatings. An adaptive a posteriori procedure for parametric formation of the target quality functional of integrative physical and mechanical properties of the designed metal coating has been proposed. The results of the research may serve as elements of a mathematical language when creating automated design of precision nanotechnologies for surface hardening of complex composite metal coatings on the basis of complex tribological and anticorrosive tests.

Study on trifluoromethanesulfonic acid-promoted synthesis of daidzein: Process optimization and reaction mechanism

Daidzein has been widely used in pharmaceuticals,nutraceuticals,cosmetics,feed additives,etc.Its preparation process and related reaction mechanism need to be further investigated.A cost-effective process for synthesizing daidzein was developed in this work.In this article,a two-step synthesis of daidzein(Friedel–Crafts acylation and[5+1]cyclization)was developed via the employment of trifluoromethanesulfonic acid(TfOH)as an effective promoting reagent.The effect of reaction conditions such as solvent,the amount of TfOH,reaction temperature,and reactant ratio on the conversion rate and the yield of the reaction,respectively,was systematically investigated,and daidzein was obtained in 74.0%isolated yield under optimal conditions.Due to the facilitating effect of TfOH,the Friedel–Crafts acylation was completed within 10 min at 90℃ and the[5+1]cyclization was completed within 180 min at 25℃.In addition,a possible reaction mechanism for this process was proposed.The results of the study may provide useful guidance for industrial production of daidzein on a large scale.

Improved process monitoring using the CUSUM and EWMA-based multiscale PCA fault detection framework

Process monitoring techniques are of paramount importance in the chemical industry to improve both the product quality and plant safety.Small or incipient irregularities may lead to severe degradation in complex chemical processes,and the conventional process monitoring techniques cannot detect these irregularities.In this study to improve the performance of monitoring,an online multiscale fault detection approach is proposed by integrating multiscale principal component analysis(MSPCA) with cumulative sum(CUSUM) and exponentially weighted moving average(EWMA) control charts.The new Hotelling's T~2 and square prediction error(SPE) based fault detection indices are proposed to detect the incipient irregularities in the process data.The performance of the proposed fault detection methods was tested for simulated data obtained from the CSTR system and compared to that of conventional PCA and MSPCA based methods.The results demonstrate that the proposed EWMA based MSPCA fault detection method was successful in detecting the faults.Moreover,a comparative study shows that the SPEEWMA monitoring index exhibits a better performance with lower values of missed detections ranging from 0% to 0.80% and false alarms ranging from 0% to 21.20%.

肉桂多糖的提取纯化及体外抗氧化和降血糖活性分析

对肉桂多糖进行提取纯化,探究其理化性质及抗氧化和降血糖活性。采用水提醇沉法,通过响应面试验考察提取温度、时间、液料比对肉桂多糖得率的影响,利用高效液相色谱法、热重分析等方法探究肉桂多糖的理化性质,并通过体外实验测试其抗氧化及降血糖活性。结果显示,最佳提取条件为温度90℃、时间2.5 h、液料比20:1(mL/g)、提取2次,此条件下平均得率为3.22%。纯化出的多糖相对分子质量为1.95×106 Da,总糖含量90.11%±1.24%,230℃以内稳定。红外光谱图显示其具有多糖的特征吸收峰,核磁氢谱显示肉桂多糖具有α、β构型等结果与红外一致,刚果红染色分析其不具有三股螺旋结构。活性测试显示肉桂多糖具有良好的抗氧化能力,三种自由基DPPH·、ABTS^(+)·、·OH的IC_(50)值分别为0.191、2.835、3.221 mg/mL,多糖6 mg/mL的总还原力值为1.18。同时肉桂多糖还对α-淀粉酶、α-葡萄糖苷酶具有抑制效果,IC_(50)值分别为0.189、0.340 mg/mL。本研究提取纯化得到一种高分子量肉桂多糖,且具有良好的抗氧化、降血糖活性,可为肉桂的功能性开发利用提供依据。

基于DANP—模糊综合评价的危化品救援队伍应急能力评估

为量化评价我国危化品应急救援队伍能力,明确应急救援队伍建设中存在的不足,通过能力素质冰山模型研究影响因素,从应急准备、应急响应和总结评估3个方面建立评估指标体系,结合集成决策实验室分析法(DEMATEL)与网络层次分析法(ANP)确定指标权重,并和DEMATEL法的权重结果进行对比,运用模糊综合评价法建立全国危化品救援队伍应急能力评价模型。结果表明:应急准备能力评价为“较弱”,应急响应能力和总结评估能力评价为“一般”,队伍总体应急能力评价为“一般”,两种权重的评价结果一致。

氢氧化镁阻燃剂的制备工艺研究进展与发展趋势

介绍了氢氧化镁(MH)阻燃剂的应用特点和作用机理,综述了MH阻燃剂的制备方法,包括物理粉碎法和化学合成法(固相法、气相法、液相法),着重介绍了液相法中的直接沉淀法、溶剂热及水热法、沉淀-共沸蒸馏法、超声化学法和微波辅助法。结合MH阻燃剂的工业应用特点,从微细纳米化、表面改性、多种制备工艺融合化研究、复合协同化和固体废弃物制备MH等5个方面对MH阻燃剂的未来发展趋势进行了展望。

噻二唑衍生物的制备及性能评价

针对现有噻二唑衍生物制备工艺中废水化学需氧量(COD)极高的问题,探索以去离子水替代乙醇作为反应溶剂,并引入相转移催化剂促进固-液两相反应,开发了制备噻二唑衍生物的绿色环保新工艺;进而,采用红外光谱、液相色谱、质谱等手段对新工艺合成的产物进行了结构表征,采用铜片腐蚀试验和四球试验评价了合成产物的金属腐蚀抑制性能、极压性能和减摩性能。结果表明:采用新工艺合成产物过程中产生的废水COD为2000 mg/L,与传统工艺产生的废水COD(700000 mg/L)相比显著降低,说明新工艺符合绿色环保要求;采用传统工艺和新工艺分别合成了2,5-双(叔壬基二硫代)-1,3,4-噻二唑,其金属腐蚀抑制性能、极压性能、减摩性能相当,且优于市售噻二唑衍生物类金属减活剂T561。

基于慢特征分析与最小二乘支持向量回归集成的草酸钴合成过程粒度预报

草酸钴合成过程是钴湿法冶炼的关键单元操作,其粒度分布是重要的质量指标,然而难以在线实时测量。同时,草酸钴合成过程通常存在非线性、多约束和慢时变特征。因此,提出一种集成慢特征分析(slow feature analysis,SFA)与最小二乘支持向量回归(least square support vector regression,LSSVR)的草酸钴粒度预报模型对草酸钴合成过程质量指标实现在线测量。在该方法中,首先,SFA方法可以有效地捕获过程的慢特征向量,解决慢时变问题;然后,利用LSSVR方法建立慢特征与粒度之间的非线性关系模型,进而实现质量指标在线预报。最后,应用非线性的数值案例以及草酸钴合成过程数据,验证该方法的有效性。实验结果显示:相较于单一的径向基函数神经网络(radial basis function neural network,RBFNN)、LSSVR预测模型以及SFA与NN相结合的预报模型,所提方法在数值案例中的预测精度分别提升了13.31%、2.26%、1.72%;在草酸钴合成过程中的预测精度分别提升了13.27%、9.96%、8.92%。

专业认证背景下的“化工过程分析与合成”课程教学

“化工过程分析与合成”课程是化学工程与工艺专业学生的一门专业核心课程,然而目前存在“化工过程分析与合成”课程教学内容与化工人才培养目标脱节的问题,为此,本文提出将案例式教学融入化工过程分析与合成的教学内容中,通过对实际工程案例的提出、浓缩,并融合进入课堂教学,实现教学模式的创新,提升教学的深度和广度,培养学生解决复杂工程问题的能力。

铜-焦脱镁叶绿酸a甲酯的合成及抗肿瘤活性研究实验教学设计

本实验设计合成了铜-焦脱镁叶绿酸a甲酯(Cu-MPPa),用于活性氧(ROS)介导的癌症治疗和消耗谷胱甘肽,并通过类Fenton反应循环产氧维持细胞内高浓度氧。实验过程中考察了Cu-MPPa的活性氧产生能力、氧气产生能力和谷胱甘肽消耗能力等性能。所合成中间体的结构用质谱进行了表征。这个实验综合了有机化学合成、仪器分析化学和生物化学实验,要求由三名学生组成实验小组,大约需要24学时,旨在培养学生综合创新能力、解决复杂问题能力和培养团队合作精神。

炮制对加味拱辰浓缩丸化学成分的影响

目的 考察炮制对加味拱辰浓缩丸化学成分的影响。方法 采用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱(UHPLC-Q-Orbitrap HRMS)法对生品组(山萸肉+当归)、炮制品组(酒萸肉+酒当归)、酒当归组(酒当归+山萸肉)、酒萸肉组(酒萸肉+当归)样品进行定性鉴别,主成分分析、正交偏最小二乘判别分析筛选差异成分,HPLC法测定莫诺苷、马钱苷、山茱萸新苷、没食子酸、阿魏酸、马钱苷酸、绿原酸、藁本内酯、5-羟甲基糠醛的含量。结果 共鉴定出97种成分,包括有机酸、环烯醚萜、苯肽、皂苷、核苷、氨基酸,生品组、炮制品组、酒当归组、酒萸肉组中分别鉴定出90、88、89、86种成分。与生品组和酒当归组比较,酒萸肉组和炮制品组中有机酸总含量升高,环烯醚萜苷总含量接近;酒萸肉组中藁本内酯含量最高。结论 酒萸肉的加入可增加加味拱辰浓缩丸组方配伍合理性,酒当归的加入也具有一定协同增效作用。

化工工艺安全评价指标体系的灰色关联度分析模型优化

安全评价指标体系承载整个评价对象的安全状态,通过对关键风险因素进行识别,可提高企业的安全级别。化工工艺安全评价指标数据量大、数据维度高、数据稳定性强,存在相近评价指标分级区分不正确的问题,因此有必要提高其安全评价相似指标的系统分辨率。结合化工工艺安全评价指标体系,构建化工工艺安全评价指标体系灰色关联度分析模型,采用“两两对比、遍历求解”的策略对灰色关联度分析模型进行系统优化,提出自适应评价指标数据规模的调节系数ρ值的确定方法,并以水煤浆气化工艺为案例进行实例分析。结果表明:采用灰色关联度分析模型对化工工艺安全评价指标重要性进行分析时,相似评价指标间区分度更大;与原模型相比,优化后的灰色关联度分析模型使系统灰色关联度的分辨率提高了15%,增加了安全评价工作的正确率。该模型对具有相同数据特点的化工工艺安全评价指标体系的确定具有一定参考作用,为更有效地评估化工企业的安全状态提供了新途径。

芬顿-ABR厌氧-生物接触氧化法组合工艺处理化学合成制药废水的工程应用

化学合成制药废水具有有机物浓度高且成分复杂的特点,通过研究废水特征,探索一种高效稳定的处理工艺。以某工程为例,采用芬顿氧化-ABR厌氧-生物接触氧化法-混凝沉淀-活性炭过滤组合工艺,对工艺进行了详细介绍。化验结果显示,废水COD、BOD_(5)、SS、NH_(3)-N的质量浓度分别为5200~5400 mg·L^(-1)、1100~1250 mg·L^(-1)、180~200 mg·L^(-1)、50~60 mg·L^(-1)、色度为80~100度。经105 d系统调试,不断优化运行控制参数,出水COD、BOD_(5)、SS、NH_(3)-N的质量浓度分别达到180 mg·L^(-1)、30 mg·L^(-1)、10 mg·L^(-1)、20 mg·L^(-1)以下,色度达到10度以下,主要污染物指标可达到《化学合成类制药工业水污染物间接排放标准》(DB41/756—2012)中的B级标准。针对此类化学合成制药废水,采用芬顿-ABR厌氧-生物接触氧化法组合工艺,技术可行,具有良好的环境效益。