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41.
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Sirish L. Shah Bhavik R. Bakshi Jinfeng Liu Christos Georgakis Benoit Chachuat Richard D. Braatz Brent R. Young 《American Institute of Chemical Engineers》2021,67(2):e17113
This white paper is the result of discussions during the FIPSE-4 conference ( http://fi-in-pse.org ) in June 2018. It aims to highlight open problems and provide directions for future research in the area of water with emphasis on its agricultural usages. Some of the open problems discussed are: (a) the use of ecosystems as unit operations to understand their role in providing freshwater and in cleaning polluted water; (b) consideration of interactions and independencies between flows of water and other resources, such as food, energy, materials, ecosystem services, and environmental emissions; (c) challenges in modeling, sensing, and closed-loop control in precision irrigation. In particular, the development of agro-hydrological models that balance computing speed versus solution details and accuracy: (d) The use of state and parameter estimation approaches, through field measurements, to obtain soil moisture levels accurately; and (e) decision support systems to administer water and nutrient needs for optimum yields of agricultural products. 相似文献
43.
Rafael N. Almeida Alírio E. Rodrigues Rubem M. F. Vargas Eduardo Cassel 《American Institute of Chemical Engineers》2021,67(10):e17351
A predictive model based on Fick's second law for radial diffusion is proposed and validated for modeling the diffusion of fragrance materials. A pure component, two binary systems, and a ternary system were used for validation. The model combines the prediction model to represent the liquid phase nonidealities, using the UNIFAC group contribution method, with the Fickian radial diffusion approach. The experimental headspace concentrations were measured in a diffusion chamber using the solid-phase microextraction technique and quantified using gas chromatography with a flame ionization detector. The numerical solutions were obtained along with an analytical model considering constant surface concentration. The odor intensities of the studied systems were calculated using Stevens' power law and the strongest component model, respectively. The numerical simulation presented good adherence to the experimental gas concentration data. The proposed methodology is an efficient and validated tool to assess the radial diffusion of fragrance and volatile systems. 相似文献
44.
ZL50装载机的换档过程平稳性决定车辆使用寿命和舒适性,这一过程是由多参数变化决定的动态过程,数值模拟方法研究这一过程,对改善车辆参数和性能有很大帮助。利用多自由度变速箱的数码表示方法和拉格朗日能量方程,建立行星变速箱各种档位都适用的通用数学模型,用该模型计算不同档位的运动学和动力学问题,对换档过程进行了数值模拟,得到行星变速箱换档过程各部件的运动学和动力学参数。 相似文献
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对工程中求取可靠的插值节点提出一种基于数理统计的方法。对足够的稳态数据进行卡尔曼滤波处理,把经过滤波后的稳态数据进行概率分布分析后,通过拟合优度检验判定测量数据的分布类型并求出合理值(数学期望)作为插值节点。以此方法处理检测区间内的采样点,得出传感器特性曲线。对某种CO2数字传感器进行实验验证,通过与传统的求均值方法进行比较,结果表明:该方法能够更加精确地估计出真实值,比普通均值拟合精度提高13%。 相似文献
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Mathematical modeling of the partial hydrogenation of vegetable oil in a monolithic stirrer reactor 下载免费PDF全文
Diego E. Boldrini Daniel E. Damiani Gabriela M. Tonetto 《American Institute of Chemical Engineers》2014,60(10):3524-3533
Experimental and theoretical studies on the partial hydrogenation of vegetable oil in a monolithic stirrer reactor are reported. A complete mathematical model of the reactor was developed, including hydrogenation and isomerization kinetics, catalyst deactivation, external gas–liquid and liquid–solid as well as internal mass transfer. The experimental studies were carried out in a Pd/Al2O3/Al monolithic stirrer reactor, at a wide range of temperatures (353–373 K), pressures (414–552 kPa), and catalyst loadings (0.00084–0.00527 kgPd,exp m?3). Based on this model, simulated data can be used to evaluate the catalyst (Pd/Al2O3/Al) and the hydrogenation process in consecutive catalytic tests under different operating conditions. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3524–3533, 2014 相似文献
49.
Optimal maintenance scheduling of a gas engine power plant using generalized disjunctive programming 下载免费PDF全文
Pedro M. Castro Ignacio E. Grossmann Patrick Veldhuizen Douglas Esplin 《American Institute of Chemical Engineers》2014,60(6):2083-2097
A new continuous‐time model for long‐term scheduling of a gas engine power plant with parallel units is presented. Gas engines are shut down according to a regular maintenance plan that limits the number of hours spent online. To minimize salary expenditure with skilled labor, a single maintenance team is considered which is unavailable during certain periods of time. Other challenging constraints involve constant minimum and variable maximum power demands. The objective is to maximize the revenue from electricity sales assuming seasonal variations in electricity pricing by reducing idle times and shutdowns in high‐tariff periods. By first developing a generalized disjunctive programming model and then applying both big‐M and hull reformulation techniques, we reduce the burden of finding the appropriate set of mixed‐integer linear constraints. Through the solution of a real‐life problem, we show that the proposed formulations are very efficient computationally, while gaining valuable insights about the system. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2083–2097, 2014 相似文献
50.
Insights into the industrial growth of cyanobacteria from a model of the carbon‐concentrating mechanism 下载免费PDF全文
Ryan L. Clark Jeffrey C. Cameron Thatcher W. Root Brian F. Pfleger 《American Institute of Chemical Engineers》2014,60(4):1269-1277
With the advent of modern bioengineering tools, photosynthetic organisms are increasingly being engineered to produce chemicals from CO2 sources, thereby creating a potential route of sustainable chemical production. Cyanobacteria have evolved a carbon‐concentrating mechanism (CCM) that enables growth at low‐environmental carbon concentrations. However at high‐carbon concentrations these benefits may not outweigh synthesis costs. Here, mass transport and kinetic modeling analyses were performed on two species of cyanobacteria as well as a hypothetical no‐CCM mutant. Modeling results correlated with published experimental data. Three conclusions were drawn from the analysis. Carboxysome geometry was unimportant due to the fast relative rate of diffusion of carbon species. Interspecies variations were largely due to active transporters. The no‐carboxysome cell approaches the wild‐type at 10% CO2. Therefore, in high CO2 environments the carboxysome and active bicarbonate transporters provide no benefit and a metabolic advantage could be achieved by eliminating the energy‐intensive CCM proteins. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1269–1277, 2014 相似文献