Bayesian Inference for ARFIMA Models

This article develops practical methods for Bayesian inference in the autoregressive fractionally integrated moving average (ARFIMA) model using the exact likelihood function, any proper prior distribution, and time series that may have thousands of observations. These methods utilize sequentially adaptive Bayesian learning, a sequential Monte Carlo algorithm that can exploit massively parallel desktop computing with graphics processing units (GPUs). The article identifies and solves several problems in the computation of the likelihood function that apparently have not been addressed in the literature. Four applications illustrate the utility of the approach. The most ambitious is an ARFIMA(2,d,2) model for the Campito tree ring time series (length 5405), for which the methods developed in the article provide an essentially uncorrelated sample of size 16,384 from the exact posterior distribution in under four hours. Less ambitious applications take as little as 4 minutes without exploiting GPUs.     

改性片麻岩为催化剂合成有机羧酸酯的研究

以改性片麻岩为催化剂合成了醋酸乙酯、醋酸丁酯、醋酸戊酯、醋酸庚酯、醋酸苄醇酯、己酸乙酯、氯乙酸异丙酯和丙烯酸 2 乙基 己醇酯 ,其收率都在 90 %以上。合成醋酸丁酯 ,催化剂重复使用 9次 ,其收率仍达 92 %～ 99% ;催化剂的寿命达 489h ,醋酸丁酯收率仍不低于 92 %。     

Microstructural Analysis and Transport Properties of Thermally Sprayed Multiple-Layer Ceramic Coatings

Multilayer, graded ceramic/metal coatings were prepared by an air plasma spray method on Ti-6Al-4V, 4140 steel and graphite substrates. The coatings were designed to provide thermal barriers for diesel engine pistons to operate at higher temperatures with improved thermal efficiency and cleaner emissions. A systematic, progressive variation in the mixture of yttria-stabilized zirconia and bondcoat alloys (NiCoCrAlYHfSi) was designed to provide better thermal expansion match with the substrate and to improve thermal shock resistance and cycle life. Heat transfer through the layers was evaluated by a flash diffusivity technique based on a model of one-dimensional heat flow. The aging effect of the as-sprayed coatings was captured during diffusivity measurements, which included one heating and cooling cycle. The hysteresis of thermal diffusivity due to aging was not observed after 100-h annealing at 800 °C. The measurements of coatings on substrate and freestanding coatings allowed the influence of interface resistance to be evaluated. The microstructure of the multilayer coating was examined using scanning electron microscope and electron probe microanalysis.     

Modelling methods for co-fired pulverised fuel furnaces

Co-firing of biomass and coal can be beneficial in reducing the carbon footprint of energy production. Accurate modelling of co-fired furnaces is essential to discover potential problems that may occur during biomass firing and to mitigate potential negative effects of biomass fuels, including lower efficiency due to lower burnout and NOx formation issues. Existing coal combustion models should be modified to increase reliability of predictions for biomass, including factors such as increased drag due to non-spherical particle sizes and accounting for organic compounds and the effects they have on NOx emission. Detailed biomass co-firing models have been developed and tested for a range of biomass fuels and show promising results.     

铁矿石粉煤基直接还原的热重分析

对大同烟煤-铁矿石粉的混合物进行了非等温热重-红外联用实验与分析,确定了铁矿石粉发生还原反应的温度区间范围,并结合还原产物的XRD图谱以及热重的定量计算结果,揭示了每个还原阶段完成后产物的物相及相应的还原分数。为了比较,进一步用热重分析仪对大同烟煤、神木褐煤以及阳泉无烟煤与铁矿石粉的混合物进行了非等温失重特性的对比实验研究。结果表明,低温阶段(800～950℃)大同烟煤对铁矿石粉的还原性最好,而高温阶段(1000～1100℃)神木褐煤也表现出良好的还原性。     

叠层结构抗震橡胶

该专利介绍的叠层结构抗震橡胶,由金属板等硬质板材和橡胶层交替叠层在一起形成的叠层体构造。其中,橡胶层具有一定的硬度,可以改善弹性特性对温度的敏感性,具有较高的衰减特性。橡胶层采用以天然橡胶以及二烯类合成橡胶为主体成分的橡胶材料制成,在100份橡胶材料中,配合了60～120份氮吸附比表面积为100～230m2/g的炭黑,10～60份经过酚醛树脂改性的双环戊二烯,该酚醛树脂中含有碳原子数为12的烷基苯酚。最后,将胶料压入金属板材之间硫化成型。     

ICP-AES测定银内胆水杯中有害元素迁移量

建立了一种基于电感耦合等离子体原子发射光谱法(ICP-AES)测定银内胆水杯中6种有害元素(砷、镉、铬、镍、铅和锑)迁移量的方法。结果表明,待测元素在标准曲线浓度范围内均呈良好线性关系,加标回收率86.1%～103.3%,相对标准偏差(RSD)均小于5%。在酸性迁移条件下,部分样品可检出一定量的锑元素迁移量,锑迁移量为0.00868～0.0304 mg/dm2。可为银餐具安全评价提供技术支持。     

离子液体[BPy]BF_4双水相萃取芦丁的研究

建立了由亲水性离子液体四氟硼酸N-丁基吡啶[BPy]BF4和(NH4)2SO4形成的双水相体系萃取分离芦丁的新方法。研究了(NH4)2SO4浓度、芦丁溶液浓度、离子液体用量和溶液酸度对双水相形成和萃取率的影响。结果表明,当双水相体系组成为:(NH4)2SO41.5 g,2.0 mL离子液体,1.0~1.2 mL芦丁溶液,溶液酸度在pH4~6范围内,该离子液体双水相体系对芦丁有较高的萃取率(E%>90)。     

Thermophysical Properties of ZrB2 and ZrB2–SiC Ceramics

Thermophysical properties were investigated for zirconium diboride (ZrB₂) and ZrB₂–30 vol% silicon carbide (SiC) ceramics. Thermal conductivities were calculated from measured thermal diffusivities, heat capacities, and densities. The thermal conductivity of ZrB₂ increased from 56 W (m K)⁻¹ at room temperature to 67 W (m K)⁻¹ at 1675 K, whereas the thermal conductivity of ZrB₂–SiC decreased from 62 to 56 W (m K)⁻¹ over the same temperature range. Electron and phonon contributions to thermal conductivity were determined using electrical resistivity measurements and were used, along with grain size models, to explain the observed trends. The results are compared with previously reported thermal conductivities for ZrB₂ and ZrB₂–SiC.     

高衰减橡胶支承体及其胶料

高衰减叠层橡胶具有衰减性大,剪切弹性模量低,在长期反复经受剪切变形的条件下剪切弹性模量提高不多及长期稳定性好等特征。这种高衰减支承体用胶料是在100份二烯类橡胶中配合50-90份炭黑,5-45份石油树脂。炭黑的氮吸附比表面积（N2SA）为150-300 m2/g,DBP吸油值在115cm3/100g以下,氮吸附比表面积（N2SA）和溴代十六烷基三甲胺吸附比表面积（CTAB）之差为5-34m2/g。高衰减支承体由高衰减胶料和硬质板材交替叠层经模压而成。