木素磺酸盐在固体颗粒表面的吸附性能

引　言木素磺酸盐是亚硫酸法生产纸浆或纤维浆的副产物 ,来源于可再生资源 ,具有吸附分散性、黏结性、流变性和胶体性质等表面物化特性 ,广泛应用在染料、涂料、石油工业和建筑业等领域 .木素磺酸盐是具有C3～C6 疏水骨架和以磺酸根为主的亲水性基团的阴离子表面活性剂 ,具有强     

Bilinear model predictive control of grade change operations in paper production plants

In this work the bilinear model predictive control method is applied to control the grade change operations in paper production plants. Because of the high nonlinearity of the grade change processes, control of the grade change operations has been performed manually by experienced engineers in the plants. In some cases the bilinear model can be very effective to represent nonlinear processes. In this study a bilinear model for paper plants is identified first. It is found that the bilinear model tracks the plant without significant discrepancy. Based on the multivariable bilinear plant model the optimal input variables are computed using the one-step ahead prediction method. Even for frequent changes in paper grades the bilinear model predictive control scheme exhibits good control performance.     

A study on the adaptive predictive control method for multivariable bilinear processes

A predictive control method for multivariable bilinear processes is derived based on ARMA model. To identify bilinear process models, we use simple equation error method extended to multivariable system. We can obtain the adaptive predictive controller for multivariable bilinear processes by incorporation of the identification algorithm. Offset compensator is provided to correct for the effects of unmeasured disturbances and model inaccuracies. A filter with a singled parameter is used to correct for the effects of an incorrect model. Results of simulation on multivariable bilinear processes show that the proposed control method has satisfactory performance.     

A Space-Time Bilinear Model and its Identification

In this paper we propose a class of space–time bilinear (STBL) models which can be used to model space–time series which exhibit bilinear behavior. The STBL model is shown to be an extension of a space–time autoregressive moving-average model and a special form of the multiple bilinear model. We focus on the identification procedure of the models. Some results about stationarity and the covariance structure of these models are also discussed. An identification procedure based on the squared observations is established for the simplest pure bilinear model and some illustrative examples are provided.     

Maximum likelihood estimation in space time bilinear models

The space time bilinear (STBL) model is a special form of a multiple bilinear time series that can be used to model time series which exhibit bilinear behaviour on a spatial neighbourhood structure. The STBL model and its identification have been proposed and discussed by Dai and Billard (1998 ). The present work considers the problem of parameter estimation for the STBL model. A conditional maximum likelihood estimation procedure is provided through the use of a Newton–Raphson numerical optimization algorithm. The gradient vector and Hessian matrix are derived together with recursive equations for computation implementation. The methodology is illustrated with two simulated data sets, and one real-life data set.     

木素磺酸钙的氧化改性研究

研究了木素磺酸钙 (简称木钙 )的氧化改性工艺 ,比较了几种氧化剂与木钙反应后性能的差异。结果表明 ,过氧化氢对木钙的聚合或降解作用均较弱 ,过硫酸铵在适宜的条件下可使木钙发生聚合反应 ,并显著改善木钙的表面物化性能。过硫酸铵氧化木钙时 ,适宜的氧化条件是过硫酸铵的用量为 4%～ 6 % ,反应温度为 80～ 90℃ ,pH =8～ 10。初步探讨了木钙的氧化聚合机理 ,过硫酸铵在碱性条件下使木钙酚型物发生离子化脱氢 ,产生了游离基 ,从而提高了木钙的反应活性 ,促进了木钙分子游离基之间的聚合反应。     

Extremes of bilinear time series models

The class of bilinear time series models is an obvious generalization of linear ARMA models and has found many applications in time series modeling. It is known that the sample paths of even the simplest bilinear process may have sudden bursts of large negative and positive values that vary in form and amplitude depending on the model parameters. Yet, little is known about the extremal properties of this class. In this paper, we look at the extremal properties of bilinear processes and explain how model parameters affect the extremal behavior.     

含碱改性高岭土裂化催化剂的表征和反应性能

利用N₂吸附法、IR酸性表征、XRD等手段研究了碱改性高岭土（CLS）的孔结构和酸性特征。从重油分子的裂化原理出发，设计了含有碱改性高岭土的新型重油裂化催化剂，并在固定流化床反应装置上进行了评价。结果表明，高岭土经过热和化学改性，形成了一定活性的中孔结构，所设计的新型重油催化剂具有很强的重质油转化能力和良好的裂化产物选择性。     

不同相对分子质量木质素磺酸钙在盾构砂浆中的应用

在对木质素磺酸钙进行超滤分级，并对其不同相对分子质量（M）的级分进行红外光谱表征的基础上，实验研究了不同M的级分对盾构砂浆工作性能的影响。结果表明，中高M级分对砂浆性能的影响最大，掺量为0.4%（质量分数）时，其减水率达9.4%，砂浆的流动度从193 mm提高至243 mm，3 h内砂浆的流动度损失率由71.6%降为43.0%，2 h内砂浆的泌水率由5.1%下降到1.0%。在实验的基础上，提出了可以通过适当增大M的方法提高木质素磺酸钙的应用性能。     

A Novel Data-Driven Bilinear Subspace Identification Approach

Subspace identification methods for bilinear systems perform computation with data matrix exploding. Huge computational burdens have been the biggest problem that prohibits real applications of bilinear subspace identification. In this paper, we propose a novel approach with the identification of bilinear predictor model from input-output data with enhanced computational efficiency. Based on the displacement structure theory, the QR factorization is replaced with a fast Cholesky factorization, which deals with the curse of huge dimensionality and therefore reduces the computation cost. These improvements make the bilinear subspace approach more computationally efficient with good prediction ability. Finally, the proposed control approach is illustrated with a simulation of the non-linear continuously stirred tank reactor (CSTR) system.     

Field-assisted sintering and phase transition of ZnS-CaLa2S4 composite ceramics

In the present study, zinc sulfide (ZnS) and calcium lanthanum sulfide (CaLa₂S₄, CLS) composite ceramics were consolidated via field-assisted sintering of 0.5ZnS-0.5CLS (volume ratio) composite powders at 800–1050 °C. Through sintering curve analyses and microstructural observations, it was determined that between 800 and 1000 °C, grain boundary diffusion was the main mechanism controlling grain growth for both the ZnS and CLS phases within the composite ceramics. The consolidated composite ceramics were determined to be composed of sphalerite ZnS, wurtzite ZnS and thorium phosphate CLS. The sphalerite-wurtzite phase transition of ZnS was further demonstrated to be accompanied by the formation of stacking faults and twins in the ceramics. It was also found that the addition of the CLS phase improved the indentation hardness of the ceramics relative to pure ZnS by homogeneous dispersion of ZnS and CLS small grains.     

木质素磺酸钙对硬化水泥抗压强度的影响

木质素磺酸盐(简称木盐)具有较强缓凝和引气作用,可提高混凝土工作性,但过量使用会导致混凝土抗压强度急剧下降。该文从掺量、相对分子质量、亲水基、金属阳离子和糖分5个方面研究了木质素磺酸钙(简称木钙)对硬化水泥抗压强度的影响规律。结果表明,随木钙掺量增加,硬化水泥的各龄期抗压强度均下降,掺量w(木钙)=0.5%时,硬化水泥的28 d抗压强度仅为空白浆体的63.6%。其中相对分子质量为1万~5万的木钙超滤级分对硬化水泥强度的降低作用较小。木钙中糖分质量分数由12.5%降至2.8%时,硬化水泥的7 d抗压强度比可提高16%。通过氧化将木钙分子中的羟基转化为羧基,硬化水泥的3、7、28 d抗压强度比分别提高22.1%、34.7%和13.0%;通过磺甲基化将木钙的磺化度由1.36 mmol/g提高到2.48 mmol/g,硬化水泥的3、7、28 d抗压强度比分别提高36.2%、41.2%和17.9%。     

INFERENCE FOR A SPECIAL BILINEAR TIME‐SERIES MODEL

It is well known that estimating bilinear models is quite challenging. Many different ideas have been proposed to solve this problem. However, there is not a simple way to do inference even for its simple cases. This article proposes a generalized autoregressive conditional heteroskedasticity‐type maximum likelihood estimator for estimating the unknown parameters for a special bilinear model. It is shown that the proposed estimator is consistent and asymptotically normal under only finite fourth moment of errors.     

ADAPTIVE MODEL PREDICTIVE CONTROL FOR SINGLE INPUT-SINGLE OUTPUT BILINEAR SYSTEMS WITH STABLE INVERSES

An adaptive control system for bilinear processes with stable inverses and without time delay is developed from a bilinear model predictive control algorithm and a projection identification algorithm. If the disturbance is bounded, the control error is bounded and the identification converges. If the disturbance is constant, the control error often converges to zero.     

Synthesis and photoluminescence properties of novel Ca2LaSbO6:Mn4+ double perovskite phosphor for plant growth LEDs

A novel Mn⁴⁺ activated Ca₂LaSbO₆ (CLS) far-red phosphor was synthesized by high temperature solid state reaction. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence spectra, ultraviolet-visible spectra, luminescence decay times, emission-temperature relationship and internal quantum efficiency (IQE). It is found that CLS:Mn⁴⁺ phosphor has a strong broad excitation band in the range of 200–550?nm. The samples can be excited by ultraviolet and blue light. There is a wide emission band centered at 685?nm between 600?nm and 760?nm. The optimum doping concentration of Mn⁴⁺ is approximately 0.5?mol%. In addition, all the CIE chromaticity coordinates of CLS:0.005Mn⁴⁺ located at far-red region. The concentration quenching mechanism is the dipole-dipole interaction of Mn⁴⁺ activator. Importantly, the CLS:0.005 Mn⁴⁺ sample has an IQE of up to 52.2%. Finally, a 365?nm ultraviolet light emitting diode (LED) chip combined with 0.5?mol% Mn⁴⁺ far-red phosphor was used to fabricate the LED device. All the results indicated that CLS:Mn⁴⁺ phosphors have potential applications in indoor plant cultivation.     

DIFFERENCE EQUATIONS FOR HIGHER-ORDER MOMENTS AND CUMULANTS FOR THE BILINEAR TIME SERIES MODEL BL(p, 0, p, 1)

Abstract. In this paper we obtain difference equations for higher-order moments and cumulants for the time series { X _t} satisfying the bilinear model BL( p , 0, p , 1). These equations are similar to the well-known Yule-Walker equations for the autoregressive moving-average model which are in terms of the second-order covariances. Thus they can be used for the tentative identification of bilinear models. Another application of these equations is in the computation of preliminary estimates of the parameters of the model. We shall illustrate this by means of simulations for two simple examples of bilinear models.     

Hypercrosslinked functionalized lignosulfonates prepared via Friedel–Crafts alkylation reaction for enhancing Pb(Ⅱ) removal from aqueous

ABSTRACT

Hypercrosslinked functionalized lignosulfonates (CLS) were prepared by Friedel–Crafts alkylation reaction. The structure of CLS without introducing any functional groups and the according adsorption behaviors of Pb(II) were characterized and studied, respectively. Due to increase of specific surface area and abundance exposure of binding sites, the maximum adsorption capacity of CLS was found to be as high as 74.45 mg/g, which was about seven times that of raw lignin. The results provide a new feasible synthesis method for preparing lignin-based materials with porous structures and promising application for the removal of heavy metal ions from wastewater.     

Source-based discrete and continuous-time formulations for the crude oil pooling problem

The optimization of crude oil operations in refineries is a challenging scheduling problem due to the need to model tanks of varying composition with nonconvex bilinear terms, and complicating logistic constraints. Following recent work for multiperiod pooling problems of refined petroleum products, a source-based mixed-integer nonlinear programming formulation is proposed for discrete and continuous representations of time. Logistic constraints are modeled through Generalized Disjunctive Programming while a specialized algorithm featuring relaxations from multiparametric disaggregation handles the bilinear terms. Results over a set of test problems from the literature show that the discrete-time approach finds better solutions when minimizing cost (avoids source of bilinear terms). In contrast, solution quality is slightly better for the continuous-time formulation when maximizing gross margin. The results also show that the specialized global optimization algorithm can lead to lower optimality gaps for fixed CPU, but overall, the performance of commercial solvers BARON and GloMIQO are better.     

Early hydration of C3A–gypsum pastes with Ca- and Na-lignosulfonate

The early age phase development during the hydration of C₃A–gypsum pastes with 1 and 4% Ca- or Na-lignosulfonate (CLS and NLS) was investigated using isothermal calorimetry, in-situ XRD, thermogravimetry, mass spectroscopy, and SEM analysis. With 1% CLS or NLS neither retardation of C₃A dissolution nor retardation of ettringite formation was observed. When LS was added in a concentration of 4%, C₃A and gypsum dissolution were slightly retarded. Gypsum depletion was delayed in all pastes containing CLS or NLS. 1% CLS or NLS increased the amount of AFm-phases formed within 24 h, while the amount of AFm was reduced with 4% CLS or NLS. The initial heat flow increased and the heat flow in the gypsum depletion peak was reduced with 1 and 4% CLS. With 4% NLS no initial heat flow was measured and the heat developed slowly within the first 15 min of hydration in the C₃A–gypsum paste.     

Formation of Calcium Lanthanum Sulfide by Carbonate Coprecipitation and CS2 Sulfurization

Pure calcium lanthanum sulfide (CLS) powders with various La/Ca ratios were prepared by a carbonate coprecipitation method and CS₂ sulfurization. Four coprecipitation processes were investigated by conventional titration, and a suitable means for coprecipitating CLS was found. By that process, a cation solution containing La³⁺ and Ca²⁺ ions was added to the precipitation medium (an anion solution of ammonium carbonate) with stirring. Precursors with various La/Ca ratios were synthesized and then sulfurized for 3 h using CS₂ as a sulfurizing agent. In the range of La/Ca ratios from 2 to 5, the intermediate phase of sulfide powder was LaS₂, and the CLS formation temperature could be increased by increasing the La/Ca ratio. For powder with high La/Ca ratios (La/Ca = 10, 15), and LaS₂intermediate phase formed at low temperature (700°C), a (β-La₂S₃ minor phase at 800°C, and a pure CLS phase after 950°C treatment. The resulting pure CLS powder was spherical, with slight necking in the submicrometer range.