生物质近红外光谱模型传递方法的研究

在建立近红外光谱预测模型时,由于受到环境、温度以及其他因素的影响,使得原模型无法预测新样本成分,造成模型预测精度的下降。文章探讨了基于近红外光谱技术的林木类生物质工业分析的预测模型在不同时间之间的转移方法,即采用斜率/截距校正和分段式直接校正两种方法进行研究。结果表明:采用斜率/截距方法后,对于工业分析,模型的RMSEP比转移前分别降低了0.91,0.78,1.23和1.03,R2分别上升了96.97%,37.99%,23.83%和23.51%;采用分段式直接校正方法后,模型的RMSEP比转移前分别降低了0.93,0.83,1.24和1.08,R2分别上升了102.22%,43.73%,26.92%和29.35%。经过模型转移方法处理后,预测结果的精度有较大程度的改善,尤其是采用分段式直接校正方法的效果更为明显。     

硅光电池的光谱响应测试技术

以精密单色仪、斩波器SR540、卤钨灯光源、样品室和自主研发的交流放大滤波电路等硬件搭建成一套光谱响应测试系统。该系统软件以VC++6.0为开发平台,主要实现了计算机对单色仪中的扫描仪参数设置以及波长连续扫描控制,精确测量波长400~1 100 nm的光谱响应值;利用光谱响应理论公式,采用最小二乘法可对单晶硅的性能参数(SP、LP和SN、LN)实现自动拟合。     

城市湖泊水体COD的近红外光谱法快速检测

将近红外光谱法与偏最小二乘法(PLS)相结合,快速检测了水体成分相对稳定的城市湖泊水体化学需氧量,通过主成分分析再结合欧氏空间距离聚类法筛选具有代表性的样本,并从系统独立变量数判断了主成分数,构建了数学校正模型,并对预测集样品含量进行预测.试验结果表明,该模型预测效果较好,为化学需氧量检测提供了一种软测量方法.     

基于最小二乘支持向量机的生物质热值预测

生物质的热值与其组成成分有关,基于此,应用最小二乘支持向量机方法建立了生物质热值预测的有效模型,并利用Biomass Feedstock Composition and Properties Database数据库提供的数据进行了测试。以该数据库的部分生物质的固定碳、挥发分和灰分含量作为输入,以相应的热值作为输出,训练最小二乘支持向量机。训练完成后,用剩余的生物质进行测试。测试结果表明,预测方法准确,速度较快。与神经网络方法相比,基于最小二乘支持向量机的生物质的热值预测方法更有效。     

生物质气化过程最小二乘支持向量机建模探讨

生物质气化过程的最终目标就是尽可能得到更多的高品质可燃气体,而目前的生物质气化过程还存在许多尚待解决的问题,例如气化温度、气化剂当量比、气化效率、燃气热值等参数优化问题.为此建立一种能适应生物质气化过程的模型,用于预测生物质气化气组分、热值、气化效率及碳转化率等指标,以及实现气化过程的参数优化都具有现实意义.本文在对生物质气化过程建模现状分析基础上,初步提出一种基于最小二乘支持向量机的气化过程建模方法,探讨了该方法用于生物质气化过程建模以及对气化过程主要参数进行优化的可行性.     

石油的近红外光谱（NIR）特征

石油是一种化学成分（性质）随它的天然生成、搬运和储集条件的不同而变化的产品。特别是在巴两，原油来源于许多以生产重质油为显著特征的不同油田。本文提供一种基于近红外光谱的原油模拟蒸发作用评价的一种方法论。     

改进的PLSR算法在大坝安全监控中的应用

针对自变量中含有过多与因变量无关的信息时应用偏最小二乘回归算法将出现偏差的问题,引入改进的偏最小二乘回归算法对坝体水平位移建立数学模型,并以安徽陈村混凝土拱坝为例进行分析.结果表明,改进的偏最小二乘回归算法通过正交投影变换解释矩阵能有效改善噪音的影响,建立的统计模型在保证解释能力的前提下其拟合效果和预测能力较偏最小二乘回归算法均有所提高.     

生物质液化技术面临的挑战与技术选择

生物质液化技术可将低品位的固体生物质完全转化成高品位的液体燃料或化学品,是生物质能高效利用的主要方式之一。按照机理,液化技术可以分为热化学法、生化法、酯化法和化学合成法(间接液化),热化学法液化又分为快速热解技术和高压液化(直接液化)技术。生物质热化学法液化已成为国内外生物质液化的研究开发重点和热点,快速热解液化技术和高压液化技术是最具产业化前景的生物质能技术,生化法液化技术也是生物质能的研究热点。化学合成法液化技术并不适用于生物质液化,而利用生物柴油进一步生产生物航空煤油是得不偿失的,不仅成本高、资源利用率低,而且全生命周期碳排放增加,还不符合未来生物航煤的发展趋势。生物质含水量的高低是影响生物质液化过程中能耗、效率、污染指数和经济性指标等的关键因素,应根据含水量合理选择生物质液化技术。快速热解液化技术适用于低含水农林废弃物,高压液化和生化法液化技术适用于高含水生物质,酯化法液化技术适用于不可食用油脂,而各种液化技术均不适用于城市生活垃圾的处理,建议将其用作燃气型气化原料。     

近红外光谱分析技术预测煤质挥发分含量模型的研究

应用近红外光谱方法进行煤质在线分析工作的研究,主要进行煤中挥发分的测定。在阅读了多个光谱图的基础上,采用多元回归方法对数据进行了分析和处理,建立了多元线性模型,该模型得出的煤中挥发分的预测值与人工化验标准值之间的相关系数为0．96,所建模型的定标标准差为1．41。     

入炉污泥含水率对污泥干化焚烧工艺影响研究

以上海某污水处理厂为例,通过理论计算和工程设计分析,研究了入炉污泥含水率(质量分数)对污泥干化焚烧工艺的影响.结果表明,随着干化程度的提高,对干燥机处理能力的要求提高,对干燥机型式的选择余地缩小,对焚烧炉、余热锅炉等设备的要求也将提高,对设备材质、系统安装、运行管理的要求也将相应提高.随着污泥干化程度的降低,进料量和烟气量增大,导致焚烧和烟气处理设备体积庞大.由于污泥泥质特性随时间变化大,在污泥热值整体偏低的地区,采用60%入炉污泥含水率存在一定的风险.污泥入炉含水率对污泥焚烧处理工程中的工艺选择及布置影响较大,工程设计中不应简单照搬国内外类似工程,而应根据当地污泥泥质特性、热值、辅助热源等实际情况,合理选择入炉污泥含水率.     

Influence of moisture content on measurement accuracy of porous media thermal conductivity

The thermal conductivity measurement accuracy of sand was experimentally studied with a hot disk thermal constant analyzer and water morphologies, distribution, and evolution at the pore scale were observed with a charge coupled device (CCD) combined with a microscope. It was found that thermal conductivities of samples with low moisture content (<25%) could not be accurately measured. For samples with low moisture content, the analysis showed that the water in the region adjacent to the analyzer sensor mainly existed as isolated liquid bridges between/among sand particles and would evaporate and diffuse to relatively far regions because of being heated by the sensor during measurement. Water evaporation and diffusion caused the sample constitution in the region adjacent to the sensor to vary throughout the whole measurement process, and accordingly induced low accuracy of the obtained thermal conductivities. Due to high water connectivity in pores, the rate of water evaporation and diffusion in porous media of high moisture content was relatively slow when compared with that of low moisture content. Meanwhile, water in the relatively far regions flowed back to the region adjacent to the sensor by capillary force. Therefore, samples consisting of the region adjacent to the sensor maintained the constant and thermal conductivities of porous media with relatively high moisture content and could be measured with high accuracy. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20272     

润滑油含水量在线监测研究

分析了燃气轮机、汽轮机润滑油(透平油)中水分产生的原因、形态以及对设备的危害,借助于先进的湿度传感器技术和在线监测方法,研制了一套润滑油中含水量在线监测系统,实现了润滑油中含水量的在线监测和数据存储管理,并对湿度传感器在润滑油环境中的特性进行了详细的实验研究。     

Initial moisture effects on herbal biomass torrefaction behavior: Gaseous products evolution and char structure analysis

Initial moisture effects on biomass torrefaction were investigated by thermogravimetric (TG) and Fourier transform infrared spectrometer (FTIR) methods. Mass degradation properties, gaseous products’ evolution characteristics, and biomass char chemical structural features were studied. Results show that during torrefaction process, the evaporation of water will create a porous structure inside the solid particles, hence extend the mass loss time intervals. Gaseous products’ evolutions were favored, while tar was reduced because of enhanced secondary decomposition. Char structure analysis suggested that –OH stretch was slightly strengthened through water molecule decomposition and other radical reactions, which would increase the reactivity of char gasification and combustion.     

Effect of hydrothermal dewatering on the moisture content of brown coal

Brown coal was dewatered under hydrothermal dewatering (HTD) conditions. The variation in moisture content and distribution of brown coal were studied. The results showed that equilibrium moisture content decreased from 28.2% to 9.6% after hydrothermally treated at 300 ºC. Three types of moisture existed in brown coal and its HTD products according to the coal-water binding energy (E_b): Surface adsorption water (E_b < 2000 kJ/kg), interparticle water (2000 < E_b < 9000 kJ/kg), and interior adsorption water (E_b > 9000 kJ/kg). Drying rates of these types of moisture? respectively followed logarithmic, linear, and indicial equations.     

Estimation of the effect of biomass moisture content on the direct combustion of sugarcane bagasse in boilers

Many of the large-scale biomass combustion systems for producing heat, hot water, or steam accept biomass fuels containing relatively large amounts of moisture. Dry biomass burns at higher temperatures and thermal efficiencies than wet biomass. Flame temperature is directly related to the amount of heat necessary to evaporate the moisture contained in the biomass, the lower the moisture content, the lower the amount of energy needed to remove the water and the higher the boiler efficiency. In this article, a simple predictive tool is developed to estimate boiler efficiency as a function of stack gas temperature and sugarcane bagasse moisture content. The method quantitatively illustrates the effect of moisture content on the performance of a thermochemical process, for the direct combustion of sugarcane bagasse in a conventional boiler. The results are found to be in excellent agreement with reported data in the literature with average absolute deviation being around 1%. The tool developed in this study can be of immense practical value for engineers to have a quick check on biomass moisture content on the boiler performance at various conditions without opting for any experimental trials. In particular, engineers would find the approach to be user-friendly with transparent calculations involving no complex expressions.     

基于改良BP神经网络的生物质锅炉飞灰含碳量预测模型研究

针对生物质锅炉飞灰含碳量较高的问题,文章提出了基于主成分分析法(PCA)或Garson算法与普通LM-BP神经网络相结合的两种生物质锅炉飞灰含碳量预测模型。这两种模型通过对负荷、燃烧室烟气温度、烟气含氧量等17个原始输入变量进行降维得到新输入变量,再进行训练建模,提高了模型精度。利用我国某生物质电厂飞灰含碳量的实测数据对模型进行检验,检验结果表明,LM-Garson-BP神经网络的MAPE为2.09%,MSE为0.11,MAE为0.25,泛化能力最强,稳定性最好。     

A New Capacitance Probe for Measuring the Local Moisture Content in Wet Porous Media

INTRODUCTIONInthestudyofheatandmasstransferprocessesinwetporousmedia,theaccurateandquickmeasure-melltofmoisturecontentdistributioninwetporousmediaiscriticaltounderstandingheatandmasstransportmechanismsintheprocesses.ButthelackofPracticalmeasurementmethodformeasuringthemoisturefieldhinderedthestudyanddevelopmentofthefulldamefitalsoftheheatandmasstransferinwetporousmediatosomeextent[1].Althoughmanymethodsfordeterminingmoisturecontelltinwetporousmediahavebeendeveloped[','ltsuchasthegravimetr…     

Exergy characteristics of woody biomass

The exergy characteristics of 60 woody biomass are investigated in this study. These include the moisture-related exergy, S-related exergy, ash-related exergy, and LHV (lower heating value)-related exergy. The results obtained from this study show that the moisture-related exergy, S-related exergy, ash-related exergy, and LHV-related exergy are in the ranges of 0–1,757.52, 0–30.28, 1.46–314.93, and 6,204.83–25,759.04 kJ/kg, respectively. The exergy values of woody biomass are in the range of 7,966.35–25,901.79 kJ/kg, and they are most contributed by LHV (77.89–99.97%), followed by moisture content (0–22.06%), ash content (0.01–1.94%), and S content (0–0.18%).     

木质生物质直接液化产物的红外光谱分析

用傅立叶变换红外光谱法对木质生物质在280—380℃水中的直接液化产物进行了研究。研究表明。木质生物质的液化可以分为2个阶段,即纤维素类和木质素类的液化;最终液化产物官能团受温度的影响不大;最终液化产物是复杂的混合物,含有烃、醛、酮、酚和酯等各类化合物。