Prediction of Heat of Vapourization of Moisture from Cereal Grains - A Modelling Approach

ABSTRACT

The Henderson's EMC model in modified form was used to fit the EMC data given by Engels et al (1987) for brown, parboiled rice. The constants in the model were related to temperature. A method to find an expression for heat of vapourization of moisture from grain was developed and demonstrated using the EMC data of brown, parboiled rice. The heat of vapourization of moisture from rice was high at low moisture contents. For moisture contents above 25% (db), the moisture inside the grain behaved almost like free water.     

Heats and Entropies of Sorption of Cereal Grains : A Comparison Between Integral and Differential Quantities

Several thermodynamic properties for maize, rough rice and wheat has been calculated using desorption isotherms available in the literature. It was obtained an analytical expression to predict the differential heat (isosteric) as function of moisture content using a three parameters equilibrium model, based on enthalpy-entropy compensation effect, which takes into account the effet of temperature. Two integral heats of sorption were calculated, the first from the slopes of the iso-spreading pressure lines and the second from integration of the differential heat. This last one was used to estimate the energy requirement to remove water from initial moisture content to different final moisture levels, which is useful in drying area. Finally it was calculated the differential and integral entropies of sorption as function of moisture content.     

Characterization and Discrimination of Ancient Grains: A Metabolomics Approach

Hulled, or ancient, wheats were the earliest domesticated wheats by mankind and the ancestors of current wheats. Their cultivation drastically decreased during the 1960s; however, the increasing demand for a healthy and equilibrated diet led to rediscovering these grains. Our aim was to use a non-targeted metabolomic approach to discriminate and characterize similarities and differences between ancient Triticum varieties. For this purpose, 77 hulled wheat samples from three different varieties were collected: Garfagnana T. turgidum var. dicoccum L. (emmer), ID331 T. monococcum L. (einkorn) and Rouquin T. spelta L. (spelt). The ultra high performance liquid chromatography coupled to high resolution tandem mass spectrometry (UHPLC-QTOF) metabolomics approach highlighted a pronounced sample clustering according to the wheat variety, with an excellent predictability (Q²), for all the models built. Fifteen metabolites were tentatively identified based on accurate masses, isotopic pattern, and product ion spectra. Among these, alkylresorcinols (ARs) were found to be significantly higher in spelt and emmer, showing different homologue composition. Furthermore, phosphatidylcholines (PC) and lysophosphatidylcholines (lysoPC) levels were higher in einkorn variety. The results obtained in this study confirmed the importance of ARs as markers to distinguish between Triticum species and revealed their values as cultivar markers, being not affected by the environmental influences.     

A New Approach to Contact Drying Modelling

ABSTRACT

This paper deals with contact drying modelling. The more general models of granular material contact dryers are based on assumptions proposed by Schlunder and al. (1.21. In this paper, a sensitivity study of the models is presented in order to find and to explain the influence of the different arameters.

A new approach, based on the same Schlunder's assumptions, but with less restrictive hypothesis, which can be applied to drying in the presence of an inert gas as well as vacuum drying and which take into account phenomena which were ignored untill now such as the local grain dehydration kinetics or the vapour diffusion inside the bed has been developped.

This new model has been compared uith some experimental results found in the litterature. A good agreement between the calculated and the experimental results has been observed. Moreover, this model is able to justify some assumptions made by Schlunder, which have not been so untill now.     

A New Approach to Contact Drying Modelling

This paper deals with contact drying modelling. The more general models of granular material contact dryers are based on assumptions proposed by Schlunder and al. (1.21. In this paper, a sensitivity study of the models is presented in order to find and to explain the influence of the different arameters.

A new approach, based on the same Schlunder's assumptions, but with less restrictive hypothesis, which can be applied to drying in the presence of an inert gas as well as vacuum drying and which take into account phenomena which were ignored untill now such as the local grain dehydration kinetics or the vapour diffusion inside the bed has been developped.

This new model has been compared uith some experimental results found in the litterature. A good agreement between the calculated and the experimental results has been observed. Moreover, this model is able to justify some assumptions made by Schlunder, which have not been so untill now.     

A Bayesian Approach to Event Prediction

Abstract.  In a series of papers, Lindgren (1975a, 1985) and de Maré (1980) set the principles of optimal alarm systems and obtained the basic results. Application of these ideas to linear discrete time-series models was carried out by Svensson et al. (1996) . In this paper, we suggest a Bayesian predictive approach to event prediction and optimal alarm systems for discrete time series. There are two novelties in this approach: first, the variation in the model parameters is incorporated in the analysis; second, this method allows 'on-line prediction' in the sense that, as we observe the process, our posterior probabilities and predictions are updated at each time point.     

A Bayesian Approach to Modelling Graphical Vector Autoregressions

Abstract. We introduce a Bayesian approach to model assessment in the class of graphical vector autoregressive processes. As a result of the very large number of model structures that may be considered, simulation‐based inference, such as Markov chain Monte Carlo, is not feasible. Therefore, we derive an approximate joint posterior distribution of the number of lags in the autoregression and the causality structure represented by graphs using a fractional Bayes approach. Some properties of the approximation are derived and our approach is illustrated on a four‐dimensional macroeconomic system and five‐dimensional air pollution data.     

液相色谱-串联质谱法测定粮谷中敌百虫、辛硫磷残留量

建立了应用液相色谱-串联质谱法测定粮谷中敌百虫、辛硫磷残留量的检测方法.试样用环己烷-乙酸乙酯(体积比1:1)提取,经凝胶色谱净化,用甲醇-水(体积比1:1)定容,供液相色谱-质谱/质谱仪测定和确证,外标法定量;在辛硫磷的测定与确证过程中,应注意避光.液相流动相为甲醇-水.串联质谱仪采用电喷雾离子源,在添加了0.002～0.100 mg/kg的敌百虫、辛硫磷标准品时的回收率为78.4%～96.7%;相对标准偏差(RSD)在5.4%～12.0%之间;最低检出限为0.002 mg/kg.     

Prediction of Air Specific Heat Ratios at Elevated Pressures Using a Novel Modeling Approach

An accurate and efficient model based on least‐squares support vector machines (LSSVM) is developed for the determination of air specific heat ratios at elevated pressures. Additionally, the coupled simulated annealing optimization strategy is used to calculate the optimal values of the LSSVM parameters. A large dataset of air specific heat ratios as a function of temperature and pressure for about 170 samples is used to develop and validate the model. The leverage approach (Williams plot) is used to determine the applicability domain of the model and to detect probably erroneous data points. Comparison of the obtained results with a previously published correlation as well as an intelligent method demonstrates that the performance of the presented model is more satisfactory than that of other methods.     

A New Approach in the Kinetic Modelling of Three-Way Catalytic Reactions

Until now, the flexibility of a global kinetic approach in the modelling of three-way catalysis, for redox reactions, has met with little success. It is an approach, which is poorly adapted when considering all the physical and chemical phenomena involved in a catalytic cycle. To this end, the work presented herein describes a novel approach in the kinetic modelling which includes a comprehensive understanding of catalytic cycles. From this basis, we have established detailed reaction rate equations that successfully model three-way catalysts behaviour under different test reaction conditions.     

Drying Characteristics and Moisture Diffusivity of Distillers' Spent Grains Dried in Superheated Steam

Distillers' spent grain pellets were prepared from material with an initial moisture content of 25% (wb). These pellets were dried in pairs using superheated steam at 120°C in two orientations, horizontal and vertical. The drying characteristics, modeled by the Page equation, showed that there was a significant difference between orientations. The overall moisture diffusivity was calculated using a finite cylinder model based on Fick's law of diffusion accounting for a change in dimensions over the course of drying. The overall diffusivity values ranged from 4.08 × 10^?10 to 1.48 × 10^?8 m²/s.     

Stochastic Modelling of Grain Moisture Content.in Near-Ambient Drying

A stochastic analytical model was developed to describe the mass transfer in a thin layer of grain ventilated with unheated air. As an excitation to the drying system, a stochastic analytical model of variations in ambient air temperature and relative humidity during the drying period, based on a sine function. was used. Mean. carrelation function, variance and the standard deviation were determined for main moisture content treated as a random process. The stochastic models of variations in air temperature and relative humidity were fined to the observed historical data. The standard deviation and m ean of grain moisture content calculated from the developed analytical model were compared to changes in mean and the standard deviation obtained from the numerical deterministic model of mass transfer and hourly weather data from 17 year.     

Stochastic Modelling of Grain Moisture Content.in Near-Ambient Drying

ABSTRACT

A stochastic analytical model was developed to describe the mass transfer in a thin layer of grain ventilated with unheated air. As an excitation to the drying system, a stochastic analytical model of variations in ambient air temperature and relative humidity during the drying period, based on a sine function. was used. Mean. carrelation function, variance and the standard deviation were determined for main moisture content treated as a random process. The stochastic models of variations in air temperature and relative humidity were fined to the observed historical data. The standard deviation and m ean of grain moisture content calculated from the developed analytical model were compared to changes in mean and the standard deviation obtained from the numerical deterministic model of mass transfer and hourly weather data from 17 year.     

A Novel Approach for the Prediction of Hydrocarbon Thermal Cracking Product Yields from the Substitute Feedstock Composition

A method has been developed to estimate cracking yields for complex hydrocarbon mixtures based on introducing the concept of substitute mixtures of real components. A set of 20 substitute components has been selected according to the true boiling points and densities of atmospheric gas oil distillation cuts. An artificial neural network trained by the full‐scale experiments of naphthas cracking provides the prediction of the gas oil cracking yields. The disintegration of individual hydrocarbons into nine structural increments has been proposed for the uniform characterization of naphthas and substitute gas oil. Using the neural network, the yields of gas oil cracking in an industrial reactor can be predicted.     

有机化合物液体等压热容的推算

本文通过热力学推导和经验校正,提出了一个新的推算有机化合物液体等压热容的关联式.该方法适用于多种类别的化合物,包括强极性的和缔合性化合物.计算的温度范围可以从对比熔点到0.95的对比温度.用该方法计算了103个化合物的等压热容,计算结果与实验数据比较吻合,其精度优于已有的文献方法.