Moisture Range Research Articles

Assessment and application of an alternative formula to describe the hydraulic conductivity over the full moisture range

AbstractMotivated by a versatile three‐parameter water retention curve (WRC) formula of Fredlund and Xing, we proposed an alternative expression to describe the relative hydraulic conductivity (RHC) for soils that can capture oven‐dry to water‐saturated conditions (full moisture range) with a single, closed‐form equation (without having to explicitly partitioning the capillary and film flow components). This RHC expression was tested using an existing data set that includes a wide range of soil textures, and shown to be more accurate than the other two RHC expressions. Subsequently, the new RHC expression was combined with the WRC formula of Fredlund and Xing, generating an alternative model (hereafter called the FL model) applicable to describe soil hydraulic properties over the full moisture range. The FL model requires both the known WRC and RHC data since three additional fitting parameters are involved in the present RHC expression. Furthermore, the FL model was employed in a HYDRUS‐1D numerical model for simulating the soil moisture redistribution within a lysimeter. The numerical simulation with using the FL model can accurately predict the moisture redistribution, in turn confirming the validity of the FL model despite without partitioning the capillary and film flow components.

The Climatic Role of Interactive Leaf Phenology in the Vegetation- Atmosphere System of Radiative-Convective Equilibrium Storm-Resolving Simulations

Storm-resolving simulations where deep convection can be explicitly resolved are performed in the idealized radiative-convective equilibrium framework to explore the climatic role of interactive leaf phenology. By initializing the system with different initial soil moisture and leaf area index (LAI) conditions, we find three categories of potential equilibrium climatic and vegetation states: a hot desert planet without vegetation, an intermediate sparsely vegetated planet, and a wet fully vegetated planet. The wet fully vegetated equilibrium category occurs over the widest range of initial soil moisture as it occurs as soon as soil saturation is 19% higher than the permanent wilting point (35%). This indicates that a quite harsh environment is needed in our modeling system to force leaves to be shed. The attained equilibrium states are only dependent upon the initial soil moisture, not the initial LAI. However, interactive leaves do allow an earlier transition from the intermediate to the wet vegetated equilibrium category. Hence, interactive leaves make the vegetation-atmosphere system more stable and more resilient to drying. This effect could be well approximated by just prescribing the LAI to its maximum value. Finally, our sensitivity experiments reveal that leaves influence the climate equally through their controls on canopy conductance and vegetation cover, whereas albedo changes play a negligible role.

Grinding characteristics and energy consumption in cryogenic and ambient grinding of ajwain seeds at varied moisture contents

The study on cryogenic and ambient grinding of ajwain seeds was envisaged to understand the energy consumption pattern during different grinding processes as a function of moisture content 8, 12, 16 and 20% (db) for AA-1, AA-2 and AA-93 varieties of ajwain seeds. The grinding time was found to increase from 57.6 ± 0.01 to 180 ± 0.08 s, whereas feed rate was found to decrease from 6.25 ± 0.07 to 2.00 ± 0.12 kg h−1 with the increasing moisture content. This resulted in more power consumption ranging from 0.012 ± 0.08 to 0.037 ± 0.007 kW h−1 in all the ajwain varieties for the selected moisture range under cryogenic and ambient grinding conditions. But the specific energy consumption was found to be higher in case of ambient grinding conditions. Also, the various energy models such as Kick's, Rittinger's and Bond's work index were found to increase significantly (p < 0.05) with increasing moisture content ranging from 1.02 to 13.22 kJ kg−1, 0.55 to 21.92 kJ kg−1 and 15.31 to 195.31 kJ kg−1, respectively. The cryogenic grinding was found to be more energy efficient than ambient grinding. Moreover, cryogenic grinding results in more yield and good quality product with uniform particle size distribution and lower powder density. This study will help the food processing industries while grinding spices and for designing of appropriate grinder specifically for grinding ajwain seeds.

Investigation of the influence of moisture during coal self-heating

During coal self-heating, the dehydration process and oxygen consumption by coal with different moisture content were analyzed. The oxidation process of aliphatic hydrocarbons, peroxyl radical, and nitrogen-, and sulfur-containing structures with/without water were evaluated by quantum chemical calculations. Our results indicate that the dehydration order of chemically adsorbed water is Ar-C(CH3)2OO·, C7H8S, C6H6S, C4H5N, Ar-CHO, Ar-CH2-OH, Ar-COOH, Ar-CH2OO·, and Ar-CH(CH3)OO·; the bituminous coal has a critical moisture range of 9.4–10.3% to maintain the balance with intrinsic reactivity. Below the critical moisture content, as moisture content decreases, the self-heating rate is the faster and the oxygen consumption rate is the greater; within 70 °C, without/with adsorbed water, the chemical adsorption of oxygen is respectively through sulfur- and oxygen-containing functional groups, and through C6H6S, C7H8S, Ar-CH2OH and Ar-CHO; at the temperature range of 70–110 °C, the oxidation of aliphatic hydrocarbons is the main reason for the oxygen consumption. Without adsorbed water, oxygen directly extracts H from the functional group to form ·OOH; peroxyl radical directly abstracts H from a nearby aliphatic structure. During the process, water acts as an H-transfer mediator. Adsorbed water promotes H abstraction by peroxyl radical from Ar-CH2OO· and Ar-CH(CH3)OO·, suppresses H abstraction by peroxyl radical from Ar-C(CH3)2OO·, promotes H abstraction by O2 from C4H5N and C7H8S, and suppresses H abstraction by O2 from thiophenol. The exothermic reactions mainly include the abstraction of H from C7H8S with adsorbed H2O by O2, and bond breakage in peroxyl radicals with/without adsorbed water, except Ar-CH(CH3)OO·.

Sewage Sludge and Municipal Solid Garbage Composting

Abstract: Co-compost could be gained by a mix of municipal solid garbage and sludge, that has been utilized in the agrarian grounds and solving municipal garbage and wastewater treatment plant issues. This investigation wants to present a method to set optimal situations like aeration speed, temperature, moisture range, C/N proportion, and particle size in composting procedure. Two pilots have been presented and in each pilot, various mixtures of municipal garbage, sludge, and wood pulp have been utilized. The size of the particle in mix and aeration speed were the distinctions between the 2 pilots. The outcomes demonstrated that the compost pile's pH has been almost ten in the start of the procedure and reduced to 7.25 slowly after seven days. The proper particle size has been 10 to 40 mm. The appropriate C/N proportion has been in the range of 25 and 35. It has been almost 33 in this experimentation. High temperatures lead to improving microbial movement in the start of the procedure. For homogenizing the temperature, it is essential for making an irritation of the compost pile each 4-6 days. An increase in co-compost temperature occurred while the moisture range has been from 50 to 60 percent. Aeration by 3 times of needed air has provided the best outcome. Ultimately, we have discovered that the moisture rate has more impact on microbial movement in comparison with the temperature. These outcomes support the utilization of the co-composting procedure by making up the size of particle and moisture abilities in preference to forced aeration-enclosed reactors.

Determination of Levels of Essential and Non-essential Metals and Nutritional Value in Mung Bean Seed (Vigna radiate L.) Cultivated in Wolaita Zone, Southern Ethiopia

Background: Mung bean (Vigna radiate L.) is an important legume crop grown worldwide from tropical to sub-tropical areas. The experiments were conducted on the mung bean to determine the level of essential and non-essential metals and proximate composition. Methods: In this study, the levels of selected essential metals and non-essential metal were determined from mung bean (Vigna radiate L.) in Kindo Koysha District, Wolaita Zone, Ethiopia. Wet digestion method with a mixture of 6 ml of concentrated HNO3:HClO4 (5:1 v/v) was used for digestion of the mung bean samples and a concentrated reagent mixture of 6 mL aqua-regia (3:1 ratio of HCl to HNO3) and 1.5 mL H2O2 was used for digestion of the soil samples. Result: The results obtained revealed that the concentrations of metals in the mung bean samples in mg/kg dry weight were in the range of Ca (1418.02-1698), Mg (2422-2492.4), Na (88.9-106.7), K (3670-3716.8), Fe (196.2-235.5), Zn (72-103), Mn (51-97.6), Cu (7.8-27.4). The non-essential metal Cr was not detected in mung beans. The proximate composition of mung bean in the range of crude protein (17.86-28.29%), crude fat (1.05-1.49%), ash content (2.9-3.35%) and moisture (5.76-7.57%). Mung bean was found to be an excellent source of essential minerals and protein content and low in fat content.

Responses of soil moisture at different slope positions to rainfall in dry-hot valley

The study of short-term dynamics of soil moisture in the dry-hot valley area during rainfall process will help identify soil hydrological function. In this study, we analyzed the short-term responses of soil moisture to rainfall in Huajiang dry-hot valley of Guizhou, using in-situ monitoring method to yield high-frequency soil moisture monitoring data of different slope positions. The results showed that, during the whole monitoring period, soil moisture at each layer was at a moderate variation level (15.2%≤coefficient of variation CV≤29.7%), for both upper slope and middle slope. The fluctuation range of soil moisture of the upper slope (CV=21.1%) was greater than that of the middle slope (CV=19.1%), and that of the 0-5 cm soil layer (CV=26.2%) was greater than 20-40 cm layer (CV=16.5%). Compared with the middle slope, soil moisture of the upper slope had a faster response to rainfall. The supplement amount of rainfall was bigger and the supplement speed of rainfall was faster at the upper slope than that at the middle slope. The difference between the supplement speed and the depletion speed of soil moisture of the upper slope (2.3%·h-1) was greater than that of the middle slope (1.8%·h-1). With the increase of soil depth, the responses of soil moisture to rainfall in subsoil layer was earlier or synchronous with that in topsoil layer. When the supplement amount of soil moisture decreased and the supplement speed slowed down, the depletion speed slowed down. Compared with the middle slope, soil at the upper slope had greater water infiltration capacity and better water retention capacity. The responses of soil moisture to rainfall in dry-hot valley were influenced by micro-environment and microclimate, and the rapid recharge of dominant flow at rock-soil interface accelerated the response speed of subsoil moisture to rainfall, which made the slopes in this area easier to form mixed runoff generation mechanism.

Effects of meteorological variables and substrate moisture on evapotranspiration and thermal performance of a green roof in a subtropical climate

This study analyzed the correlations between the meteorological/substrate-moisture variables and the evapotranspiration (ET) to improve the understanding of the factors influencing the thermal performance of green roofs, including cooling the surface and interior temperature of the building, in a subtropical climate. Daily ET of the green roof had been estimated using the FAO Penman-Monteith method to increase the number of ET data and the Nash-Sutcliffe coefficient is 0.51–0.62 compared to the observed daily ET from data of green roof experiments in Taipei during December 2012 and September 2013. Based on correlation analysis, this study then suggests that ET may have a higher influence on Tdiff, i.e. the difference in surface temperatures of green and original roofs, than the meteorological variables or substrate water content (SWC), although the radiative heating is sometimes more influential to Tdiff than the cooling caused by ET of the green roof in thin substrate condition. This study also found that under wet and dry substrates, daily ET is highly correlated with weather-related variables and with SWC, respectively. Furthermore, because of the low insulation of wet substrate, more downward fluxes are sometimes found under high than low SWC conditions. On the contrary, under the dry substrate, increasing SWC helps reduce the downward fluxes. This study, therefore, indicates that an optimal range of substrate moisture appears to maximize the function of a green roof in reducing the surface temperature and the downward substrate-bottom flux. Considering that a counterbalance exists between SWC and ET as well as irrigation can be applied to control SWC, future studies could be aimed at the optimal range of SWC to execute informed irrigation concerning the thermal performance, water-saving irrigation, and storm-water-retention function of the green roofs either in dry period or before storm events.

INFLUENCE OF KEY FACTORS AND SOIL PROCESSES ON BARLEY PRODUCTIVITY IN CROP ROTATIONS ON BLACK SOILS OF THE CIS-URAL REGION

The article shows the results of studying the influence of soil moisture, cellulose-decomposing activity of microorganisms and the amount of nutrients on barley productivity in crop rotations and monocrops in the central zone of Orenburg region. The purpose of the experiment is to identify the effect of moisture, soil cellulolytic activity and macronutrients (nitrates, phosphorus, potassium) on barley productivity increase in crop rotations and in monocrop cultivation. The following research methods were used: field, thermostatic-weight, application-weight, ionometric and Machigin methods. There was a yield increase of barley feed and energy units up to 2.10, 1.63 and 1.24, 0.96 t/ha in the second and fourth variants of the experiment on a fertilized background on average for 2002-2020. The increase of feed unit yield occurs due to productive moisture utilization by the plant during the growing season of 32.3, 32.2 mm, nitrates - 4.20, 1.91 mg, phosphorus - 1.76, 0.50 and potassium - 2.47, 1.01 mg/100 g of soil in case of cellulose- decomposing activity of microorganisms - 7.93 and 10.37%. As far as other variants of the experiment is concerned, the range of soil moisture on nutritional background is from 17.4 to 41.7 mm during sowing and 3.5-10.5 mm during harvesting; the degree of linen decomposition - 4.05-9.37%, the content of digestible nitrates - 0.05-1.11 mg, mobile phosphorus - 0.04-0.29 mg, exchangeable potassium - 0.05-0.95 mg /100 g, feed units - 1.16-1.44 t, energy units - 0.68-0.85 t per 1 ha. As a result of the study, the influence of moisture, activity of microorganisms, nutrients on barley productivity growth was determined as a result of the aftereffects of millet and peas in crop rotations after application of mineral fertilizers at a dose of 40: 80: 40 kg (N: P: K) of the active substance per 1 ha. The yield dependence of barley energy feed units in a crop rotation with millet on the content of used nitrates in the arable soil layer was found.

Microbes, memory and moisture: Predicting microbial moisture responses and their impact on carbon cycling

Abstract Soil moisture is a major driver of microbial activity and thus, of the release of carbon (C) into the Earth's atmosphere. Yet, there is no consensus on the relationship between soil moisture and microbial respiration, and as a result, moisture response functions are a poorly constrained aspect of C models. In addition, models assume that the response of microbial respiration to moisture is the same for all ecosystems, regardless of climate history, an assumption that many empirical studies have challenged. These gaps in understanding of the microbial respiration response to moisture contribute to uncertainty in model predictions. We review our understanding of what drives microbial moisture response, highlighting evidence that historical precipitation can influence both responses to moisture and sensitivity to drought. We present two hypotheses, the ‘climate history hypothesis’, where we predict that baseline moisture response functions change as a function of precipitation history, and the ‘drought legacy hypothesis’, in which we suggest that the intensity and frequency of historical drought have shaped microbial communities in ways that will control moisture responses to contemporary drought. Underlying mechanisms include biological selection and filtering of the microbial community by rainfall regimes, which result in microbial traits and trade‐offs that shape function. We present an integrated modelling and empirical approach for understanding microbial moisture responses and improving models. Standardized measures of moisture response (respiration rate across a range of moistures) and accompanying microbial properties are needed across sites. These data can be incorporated into trait‐based models to produce generalized moisture response functions, which can then be validated and incorporated into conventional and microbially explicit ecosystem models of soil C cycling. Future studies should strive to analyse realistic moisture conditions and consider the role of environmental factors and soil structure in microbial response. Microbes are the engines that drive C storage and are sensitive to changes in rainfall. A greater understanding of the factors that govern this sensitivity could be a key part of improving predictions of soil C dynamics, climate change and C‐climate feedbacks. Read the free Plain Language Summary for this article on the Journal blog.

Thermoresponsive Polymers for Water Treatment and Collection

To overcome the current scarcity of fresh water sustainably, new technologies will be required that produce potable water from a range of sources, including seawater and moisture from the atmosphere. Moreover, we must recover and reuse water from wastewater streams to reduce our global water footprint. To date, there remain significant concerns about the environmental/ecological impact, high energy consumption, and extensive maintenance costs of current technologies that might prevent their transition to more sustainable routes of potable water generation. One class of material that can enable low-energy water production is thermoresponsive polymers. Due to their unique phase behavior, production flexibility, and biocompatibility, these materials may allow for sustainable routes to fresh water in current and new technologies. In this Perspective, we specifically summarize the design and application of poly(N-isopropylacrylamide)- (PNIPAm-) based thermoresponsive microgels and hydrogels. In particular, we show how these materials have been used for water purification, including wastewater treatment, seawater desalination, and moisture harvesting from the atmosphere. Finally, we discuss the opportunities and challenges of transforming current thermoresponsive materials into practical water-related technologies.

Evaluating isotherms and isosteric heat utilization during sorption characteristics of feed barley

A well-formulated sorption model defines the grain moisture and also the energy expenses associated with drying and/or rehydration. Though literature contains adsorption and desorption models that are used to identify the hysteresis, they are not efficient to implement in sensors simultaneously when monitoring stored grain transient conditions. This study modifies the existing sorption model to fit transient monitoring criteria based on harvest moisture conditions between 11.3 and 85.9% RH at three temperatures (15, 25 and 35 °C). Feed barley was taken for the sorption study and fitted with equilibrium moisture content (EMC) and equilibrium relative humidity (ERH) equations of five widely used isotherm models, respectively. Model was fitted with EMC's attained at individual temperatures and the transfer phases between them.Sorption isotherms showed a non-smooth Type II sigmoidal trend with positive correlation between RH and EMC. The time taken to reach EMC irrespective of RH was inversely proportional to the temperature difference noted from the transfer phase. The Modified-Oswin equation (EMC) was found to be appropriate to represent the sorption isotherm of feed barley. For the transfer phases, EMC at higher temperature showed negligible difference with initial EMC phase except at 15 °C with higher RH (adsorption). Heat of sorption showed a decreasing trend with moisture and was 27% (average) higher than the latent heat of vaporization. Sorption heats for transfer phases were higher than initial EMC phases but not significantly different. Energy difference went up to 250 kJ kg−1 between 9 and 14% db moisture showing a normal distribution below and above the moisture range, respectively. Thus, future storage models should consider sorption heats for proper estimation of energy expenses during drying and rehydration.

A dielectric model of thawed and frozen Arctic organic soils at 435 MHz

ABSTRACT A refractive-mixing dielectric model for frozen and thawed organic-rich soils at a frequency of 435 MHz was developed in this letter. The model was developed based on the dielectric measurements of five soil samples in which organic matter content was variated from 35% to 80% (by weight). Dielectric measurements were conducted in the range of volumetric soil moisture from ~2% to 60%, and the range of temperature from −30°C to 25°C. Coefficient of determination (R2) and root mean square error (RMSE) between predicted by the model and measured values for real () and imaginary () part of complex relative permittivity are = 0.989 (=0.602) and = 0.906 (=0.404), respectively. The developed dielectric model can be used for creating remote sensing algorithms (soil moisture retrieval in the root zone, active layer thickness and ice content measuring in permafrost area, etc.) in P-band.

Intensify staple fibre drying by optimizing air distribution in multistage convective dryer using CFD

A non-uniform air distribution in the conveyor dryer contributes towards an uneven drying of material. In case of cellulosic fibre drying, portion of fibre bed, which is exposed to high air flow rate, dries faster compared to portion receiving lower air flow at the same temperature. Therefore, non-uniform moisture distribution is observed across the fibre bed. Along with on-field measurement, 3D Computational Fluid Dynamics (CFD) modeling was carried out to study air profile inside the convective dryer (capacity ∼x223C20 TPD). Validated model was used to design an optimum air distribution sieve to enhance the air uniformity which leads to uniform moisture across the dryer width. Five different air distribution sieves (Design – 1–5) were designed, and air velocity distribution were compared. Air distribution sieve with overall 17% opening (Design-4) shows 64% higher air uniformity from the base case which enhances production of premium grade (moisture range: 10.5–11.5%) fibres by 5% at the commercial scale. The robustness of the adopted design also shows its scalability from small (∼x223C20 TPD) to large scale dryer (capacity >100 TPD).

Moisture Sorption Behaviour of Concrete Mixtures Containing Chlorides and the Resulting Electrolytic Resistivity in Relation to the Estimated Corrosion Risk

When using corrosion monitoring on reinforced concrete structures exposed to chloride, self-corrosion can play a decisive role in the interpretation and evaluation of the results. Only a part of the corrosion current can be measured electrochemically as element current. A significant proportion of the cathode process takes place on the measuring anode electrode itself. With decreasing water content of the concrete, the ratio of self-corrosion current to measurable element current increases. Corrosion tests on this topic are currently being carried out at the Munich University of Applied Sciences in cooperation with the Technical University of Munich. The moisture sorption isotherms determined at the beginning of the corrosion tests for the concrete mixtures investigated are presented here. Additionally, the electrolytic resistivities of the concrete mixtures in dependence on their water and chloride contents have been evaluated. In consideration of literature results, a moisture range can be evaluated that is associated with harmless corrosion processes.

Modelling hydraulic conductivity for porous building materials based on a prediction of capillary conductivity at capillary saturation

Liquid moisture transport plays a key role in performance of many building assemblies. For hygrothermal simulation models, used to assess such assemblies, it is important to include realistic liquid transport properties for the specific porous building materials involved. Unfortunately, comprehensive experimental and modeling methods associated with determining the hydraulic conductivity limit widespread application of material-specific determination. To ease applicability, this paper investigates how to simplify conductivity prediction and modeling by building on a bundle of tubes approach. Incorporating a new expression variant for the capillary absorption coefficient (Aw), a novel prediction expression for the conductivity at capillary saturation (Kc,cap) is derived. modeling of unsaturated capillary conductivity (Kc) can thus be scaled to Kc,cap instead of the traditional approach of scaling to conductivity at over-capillary saturation (Ksat), avoiding some complexity and concerns one traditionally has faced. Hence, in contrast to most models for Kc, which apply Ksat, this paper applies Kc,cap as reference to scale the conductivity at unsaturated conditions. To model the hydraulic conductivity (K) for the full moisture range, Kc is coupled with a thin film model (Kfilm) and a hygroscopic correction model (Khyg). The prediction model is evaluated against a wide range of porous building material datasets found in literature as well as compared to a common alternative approach, with reasonable results. The findings of this study can help for better understanding of challenges in analytical calculation of Aw and of why bundle of tube models have accuracy issues in predicting Kc, with the study suggesting remedies for some of these issues.

Mercury intrusion porosimetry and centrifuge methods for extended‐range retention curves of soil and porous rock samples

AbstractThe water retention function is essential for modeling flow and transport in porous media. Its experimental determination is still challenging because each of the standard methods is limited to partial moisture ranges. The pore‐size distribution (PSD) obtained by the mercury intrusion porosimetry (MIP) may be used as a unifying property that spans across the individual ranges of retention properties obtained with standard methods. This study compares the MIP and quasi‐steady centrifuge (QSC) methods with standard ones (suction table, evaporation, and dewpoint potentiameter) to determine the retention curves of subsoil clods and calcareous rocks over most of the moisture range. The selected soils, having a relatively rigid structure compared with other soils, are more similar to the rocks even if there is a non‐negligible difference in terms of mechanical strength. The QSC, developed for rock samples, was tested for soil to see if the method is also applicable for mechanically less stable media. The porosity characteristics of soil and rock samples showed bi‐ and trimodal PSDs. The single MIP test allowed describing the mercury retention curve (MRC) for most of the volumetric mercury content range. The MRCs could be used to fill the gaps in the retention curves that occur with the standard retention procedure when switching from one measurement range to the other. The MIP and QSC methods proved to be relatively fast and reliable for measuring a wider range of the retention curve. However, the application of QSC method to soil samples is limited by effects of compaction due to centrifugal force.

Comparative analysis of the profile variability of black soil water-physical properties when long-term applying plowing and no-till technologies use (the case of Panfily Research Station)

The results of actual research on profile variability of soil water-physical properties of undisturbed structure at the plots, where traditional plowing and no-till technology have been applied for 11 years, are given. The comparative research was conducted based on a stationary field experiment, which is carried out at Panfily Research Station of the National Scientific Center "Institute of Agriculture NAAS" when applying a system of laboratory diagnostics of water-physical properties created in the Institute of Water Problems and Land Reclamation of NAAS based on hydrophysical methods. The characteristics of main hydrophysical functions, namely moisture conductivity and water holding capacity, as well as hydrological constants - maximum hygroscopic moisture, withering point, minimal water holding capacity, maximum water holding capacity, specific surface area and active moisture range were obtained for three different depths. &#x0D; Based on the results of comparison, it was found that mesoporosity was more developed in the soil on the plots under plowing, while macroporosity was more developed on the no-till plots. The fundamental result is determining the inversion type of profile distribution of moisture conductivity in unsaturated soil. Thus, under on the no-till plots the highest values of moisture conductivity were observed in the deepest soil layer (0,70-0,85 m), decreasing to the soil surface, while on the plots under plowing the highest values of moisture conductivity were observed in cultivated soil layer (0,00-0,15 m), which naturally decreased in depth. The profile distribution of moisture conductivity on the no-till plots contributed to the infiltration supply of groundwater and capillary feeding of soil root layers from the deeper ones.

Spectral analysis of H2O near 7180 cm–1 to accurately measure trace moisture in N2 gas: evaluation of line shape profiles using Akaike Information Criterion

The absorption spectra of H2O in N2 gas were measured at atmospheric pressure and room temperature near 7180 cm–1 in the moisture range of 9.7–148.7 nmol mol−1 in mole fraction using cavity ring-down spectroscopy. The line shape profiles used for the spectral analysis for the trace moisture measurement were evaluated based on the Akaike Information Criterion as well as the fitting residuals. The optimal line shape profile in this study was the speed-dependent asymmetric Voigt profile (SDAVP). From the comparison of the fitting results calculated using the Lorentzian profile (LP) with those calculated using the SDAVP, the relative difference in the integrated line area between the two line shape profiles was found to be systematic and constant. The measurement error due to the use of the LP could be corrected using a correction factor of 1.00479 ± 0.00077.

Wood moisture monitoring and classification in kiln‐dried timber

Different mass timber structures require a specific range of wood moisture. Thus, moisture monitoring is a crucial quality control task during timber drying that impacts the properties and quality of the subsequent timber structures. Variations in the average and distribution of the final moisture can result in significant variations in the timber properties and thus negatively affect performance in service. This necessitates rigorous moisture monitoring and timber grading during and after kiln drying. This study aims to estimate the kiln-dried population final moisture distribution based on green timber characteristics and machine learning. This will facilitate the timber grading process by reducing the variation in the mechanical properties of the kiln-dried timber, as timbers with a higher chance of moisture variation will be identified before the drying process. Timber initial moisture, initial weight, basic density, and target moisture were used to train machine learning models. Linear discriminant analysis and decision tree were used for moisture classification. Principal component and variable clustering analysis were performed to study the critical parameters affecting the timber overdrying and underdrying. The results indicated that initial moisture level and weight are the essential variables, while density had the least significant effect on the performance of classification models. The decision tree approach exhibited better performance than discriminant analysis with ~91% classification accuracy proving the effectiveness of using initial timber properties for quality control and grading of kiln-dried timber.