scholarly journals Model Based Control of Moisture Sorption in a Historical Interior

10.14311/726 ◽  
2005 ◽  
Vol 45 (4) ◽  
Author(s):  
P. Zítek ◽  
T. Vyhlídal
Keyword(s):  
Moisture Content ◽  
Moisture Sorption ◽  
Point Of View ◽  
Historical Buildings ◽  
Air Humidity ◽  
Preventive Conservation ◽  
Model Based Control ◽  
Yearly Cycle ◽  
Model Based ◽  
The Impact

This paper deals with a novel scheme for microclimate control in historical exhibition rooms, inhibiting moisture sorption phenomena that are inadmissible from the preventive conservation point of view. The impact of air humidity is the most significant harmful exposure for a great deal of the cultural heritage deposited in remote historical buildings. Leaving the interior temperature to run almost its spontaneous yearly cycle, the proposed non-linear model-based control protects exhibits from harmful variations in moisture content by compensating the temperature drifts with an adequate adjustment of the air humidity. Already implemented in a medieval interior since 1999, the proposed microclimate control has proved capable of permanently maintaining constant a desirable moisture content in organic or porous materials in the interior of a building. 

scholarly journals Modelling the moisture sorption isotherms of Roselle (Hibiscus sabdariffa L.) in the temperature range of 5–35 °C

2013 ◽  
Vol 61 (6) ◽  
pp. 1769-1777 ◽  
Author(s):  
Jitka Langová ◽  
Donludee Jaisut ◽  
Ratiya Thuwapanichayanan ◽  
Charotorn Phowong ◽  
Jiří Štencl ◽  
...  
Keyword(s):  
Moisture Content ◽  
Water Sorption ◽  
Structural Changes ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Ambient Air ◽  
Point Of View ◽  
Hibiscus Sabdariffa ◽  
Adsorption And Desorption ◽  
Moisture Sorption Isotherms

Water sorption tests of Roselle (Hibiscus sabdariffa L.) carried out under laboratory conditions are presented together with mathematical analyses of the moisture sorption isotherms (MSI’s). Moisture equilibrium data for adsorption and desorption of water from Roselle powder were investigated at near ambient air temperatures in the range of 5 and 35 °C and water activity (Aw) ranging from 0.11 to 0.97. The manometric method has been used for water sorption tests. Models for MSI’s are exponential equations. Coefficients of determination are 0.998 and 0.996 (for adsorption and desorption at 5 °C, respectively), 0.998 and 0.999 (for adsorption and desorption at 20 °C, respectively), and 0.998 and 0.999 (for adsorption and desorption at 35 °C, respectively). The equilibrium moisture content (EMC) of Roselle samples increased with an increase of Aw at a constant temperature both for adsorption and desorption. Adsorption curve equates to desorption curve at higher temperatures of tests carried out. Critical values of EMC of samples tested corresponding to the Aw equal to 0.6 were between 13.401% moisture content wet basis (MC w.b.) and 15.934% MC (w.b.) for moisture adsorption and desorption, respectively. These values are useful for storing conditions optimisation from point of view microorganisms grow and structural changes analyses. Crystal structure changes were observed during adsorption and desorption in the microscope, too. It was found out glass transition in dependence on the water content of samples tested.

scholarly journals Cylinder-specific model-based control of combustion phasing for multiple-cylinder diesel engines operating with high dilution and boost levels

2018 ◽  
Vol 21 (7) ◽  
pp. 1231-1250
Author(s):  
Wenbo Sui ◽  
Carrie M Hall ◽  
Gina Kapadia
Keyword(s):  
Steady State ◽  
Diesel Engines ◽  
Specific Model ◽  
Integral Model ◽  
Loop Control ◽  
Model Based Control ◽  
Model Based ◽  
Crank Angle Degree ◽  
Crank Angle ◽  
The Impact

Accurate control of combustion phasing is indispensable for diesel engines due to the strong impact of combustion timing on efficiency. In this work, a non-linear combustion phasing model is developed and integrated with a cylinder-specific model of intake gas. The combustion phasing model uses a knock integral model, a burn duration model, and a Wiebe function to predict CA50 (the crank angle at which 50% of the mass of fuel has burned). Meanwhile, the intake gas property model predicts the exhaust gas recirculation fraction and the in-cylinder pressure and temperature at intake valve closing for different cylinders. As such, cylinder-to-cylinder variation of the pressure and temperature at intake valves closing is also considered in this model. This combined model is simplified for controller design and validated. Based on these models, two combustion phasing control strategies are explored. The first is an adaptive controller that is designed for closed-loop control and the second is a feedforward model–based control strategy for open-loop control. These two control approaches were tested in simulations for all six cylinders, and the results demonstrate that the CA50 can reach steady-state conditions within 10 cycles. In addition, the steady-state errors are less than ±0.1 crank angle degree with the adaptive control approach and less than ±1.3 crank angle degree with feedforward model–based control. The impact of errors on the control algorithms is also discussed in the article.

Effects of the Intake Air Humidity on the Gas Turbine Performance Monitoring

2015 ◽  
Author(s):  
Houman Hanachi ◽  
Jie Liu ◽  
Avisekh Banerjee ◽  
Ying Chen
Keyword(s):  
Moisture Content ◽  
Gas Turbine ◽  
Performance Monitoring ◽  
Performance Indicator ◽  
Performance Model ◽  
Offshore Platforms ◽  
Air Humidity ◽  
Humidity Effects ◽  
Model Based ◽  
Primary Model

Gas turbine engines (GTEs) are extensively used in locations with high humidity such as offshore platforms. However, in the dry regions, GTEs are often equipped with water spray inlet coolers for warm seasons. In both cases, the moisture affects the thermodynamic properties of the intake air and drifts the performance off the dry condition, especially during the warm days, when the moisture content of the air is high and the inlet air cooler is operational. In this paper, a detailed steady state model is proposed to simulate the GTE performance with the humid air, and it is linked with a thermodynamic model to quantify the total moisture content of the air after the cooler. The developed framework is used to analyze the operating data of a GTE during the three years of service. The results are then utilized for model-based performance monitoring of the GTE, using a recently introduced performance indicator. A comparative analysis is performed between the results received from the primary model overlooking the humidity effects, and the developed enhanced performance model with humidity effects. A better accuracy for the performance indicator was observed where the enhanced model is employed, suggesting the importance of considering the intake air humidity for model-based performance monitoring.

scholarly journals Experience of Implementing Moisture Sorption Control in Historical Archives

10.14311/884 ◽  
2006 ◽  
Vol 46 (5) ◽  
Author(s):  
P. Zítek ◽  
T. Vyhlídal ◽  
J. Chyský
Keyword(s):  
Moisture Content ◽  
Moisture Sorption ◽  
Main Concern ◽  
Air Humidity ◽  
Novel Approach ◽  
Historical Archives ◽  
Direct Measurements ◽  
Art Works ◽  
Constant Moisture Content

This paper deals with a novel approach to inhibiting the harmful impact of moisture sorption in old art works and historical exhibits preserved in remote historic buildings that are in use as depositories or exhibition rooms for cultural heritage collections. It is a sequel to the previous work presented in [2], where the principle of moisture sorption stabilization was explained. Sorption isotherm investigations and EMC control implementation in historical buildings not provided with heating are the main concern in this paper. The proposed microclimate adjustment consists in leaving the interior temperature to run almost its spontaneous yearly cycle, while the air humidity is maintained in a specific relationship to the current interior temperature. The interior air humidity is modestly adjusted to protect historical exhibits and art works from harmful variations in the content of absorbed moisture, which would otherwise arise owing to the interior temperature drifts. Since direct measurements of moisture content are not feasible, the air humidity is controlled via a model-based principle. Two long-term implementations of the proposed microclimate control have already proved that it can permanently maintain a constant moisture content in the preserved exhibits. 

Method for the determination of sorption isotherms of materials demonstrated through soil samples

2011 ◽  
Vol 2 (2) ◽  
pp. 117-121 ◽  
Author(s):  
Á. Lakatos
Keyword(s):  
Moisture Content ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Soil Samples ◽  
Point Of View ◽  
Hysteresis Phenomenon ◽  
Simple Method ◽  
Sorption Behaviour ◽  
Fundamental Research ◽  
Solid Bodies

Abstract Proper understanding of sorption behaviour of the materials is important from the point of view of fundamental research and technology as well for applied building technology. In this paper a simple method is presented for measuring water sorption capability of solid bodies. Moisture sorption and desorption measurements were carried out on soil samples by using climatic chamber. After drying the samples in a Venticell 111 type drying equipment they were treated with a Climacell 111 type climate chamber, where the relative humidity (RH) was varied from 40 to 83% at 22°C for different times (40, 80, 120 and 240 minutes). The samples reached the equilibrium moisture content after 120 minutes for sorption. The desorption isotherm measurements were carried out at 22°C for 80 minutes of exposure at constant RH. At this point hysteresis phenomenon was observed. Besides the moisture content figures the time evolution of the damping process is also presented in this paper.

Model-based moisture sorption stabilization in historical buildings

2009 ◽  
Vol 44 (6) ◽  
pp. 1181-1187 ◽  
Author(s):  
Pavel Zítek ◽  
Tomáš Vyhlídal
Keyword(s):  
Moisture Sorption ◽  
Historical Buildings ◽  
Model Based

scholarly journals Improving Estimation of Soil Moisture Content Using a Modified Soil Thermal Inertia Model

2020 ◽  
Vol 12 (11) ◽  
pp. 1719
Author(s):  
Zhenhua Liu ◽  
Li Zhao ◽  
Yiping Peng ◽  
Guangxing Wang ◽  
Yueming Hu
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Data Fusion ◽  
Spatial Resolution ◽  
Soil Moisture Content ◽  
Thermal Inertia ◽  
Original Model ◽  
Estimation Accuracy ◽  
Model Based ◽  
The Impact

There has been substantial research for estimating and mapping soil moisture content (SMC) of large areas using remotely sensed images by developing models of soil thermal inertia (STI). However, it is still a great challenge to accurately estimate SMC because of the impact of vegetation canopies and vegetation-induced shadows in mixed pixels on the estimates. In this study, a new method was developed to increase the estimation accuracy of SMC for an irrigated area located in YingKe of Heihe, China, using ASTER data. In the method, an original model of estimating bare STI was modified by decomposing a mixed pixel into three components, bare soil, vegetated soil, and shaded soil, as well as extracting their fractions using a spectral unmixing analysis and then deriving their fluxes. Moreover, the 90 m spatial resolution thermal images were scaled down to the 15 m spatial resolution by data fusion of a discrete wavelet transform (DWT) and re-sampling using the nearest neighbor method (NNM). The modified model was compared with the original model based on the mean absolute error (MAE) and relative root mean square error (RRMSE) between the SMC estimates and observations from 30 validation soil samples. The results indicated that compared to the original model based on the parallel dual layer, the modified STI model based on the serial dual layer statistically significantly decreased the MAE and RRMSE of the SMC estimates by 63.0–63.2% and 63.0–63.5%, respectively. The 15 m spatial resolution thermal bands obtained by the DWT data fusion provided more detailed information of SMC but did not significantly improve its estimation accuracy than the 15 m spatial resolution thermal bands by re-sampling using NNM. This implied that the novel method offered insights on how to increase the accuracy of retrieving SMC estimates in vegetated areas.

scholarly journals A model-based control law for vibration reduction of serial robots with flexible joints

2021 ◽  
Vol 22 ◽  
pp. 38
Author(s):  
Jacques Farah ◽  
Hélène Chanal ◽  
Nicolas Bouton ◽  
Vincent Gagnol
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Control Law ◽  
Flexible Joints ◽  
Dynamic Identification ◽  
Model Based Control ◽  
Model Based ◽  
Serial Robots ◽  
Pick And Place ◽  
The Impact

The presence of flexibilities in rotational joints can limit the kinematic performances of manipulators doing high speed tasks as Pick and Place. The problem addressed in this work concerns the vibration control of serial robots with flexible joints performing Pick and Place tasks in order to improve productivity. Based on a dynamic model of a robot with flexible joints, a model-based control law is proposed with its associated tuning methodology. The robot dynamic model is then the key point of our methodology. This dynamic model considers stiffness and damping of each flexible joint. To guarantee its accuracy, a geometrical and dynamic identification procedure is realized. The objective is to show the relevancy of the proposed approach which integrates joint flexibilities in the control law. Theoretical results based on a representative model are used to illustrate the benefit of this model-based control law compare to two other control strategies (Feedforward control and control dedicated to rigid structures). Finally, a sensitivity analysis of this control law is realized to quantify the impact of modelling error and conclude on the criticality of joint damping value on vibration decreasing.

scholarly journals Analytical, Experimental, and Numerical Investigation of Energy in Hydraulic Cylinder Dynamics of Agriculture Scale Excavators

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6210
Author(s):  
Ryo Arai ◽  
Satoru Sakai ◽  
Akihiro Tatsuoka ◽  
Qin Zhang
Keyword(s):  
Parameter Identification ◽  
Numerical Investigation ◽  
Physical Parameter ◽  
Hydraulic Cylinder ◽  
Point Of View ◽  
Laboratory Scale ◽  
Model Based Control ◽  
Model Based ◽  
Modeling Errors ◽  
Numerical Simulator

This paper discusses energy behaviors in hydraulic cylinder dynamics, which are important for model-based control of agriculture scale excavators. First, we review hydraulic cylinder dynamics and update our physical parameter identification method to agriculture scale experimental excavators in order to construct a nominal numerical simulator. Second, we analyze the energy behaviors from the port-Hamiltonian point of view which provides many links to model-based control at laboratory scale at least. At agriculture scale, even though the nominal numerical simulator is much simpler than an experimental excavator, the analytical, experimental, and numerical energy behaviors are very close to each other. This implies that the port-Hamiltonian point of view will be applicable in agriculture scale against modeling errors.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

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