Low Liquid Research Articles

A Stacking Ensemble Learning Algorithm for Anomaly Early Detection of Liquid Levels in High-Pressure Heaters of Turbine Reheat Systems

In the steam turbine reheating system, maintaining the high-pressure heater liquid level is crucial to prevent equipment damage and safety accidents. High liquid levels may cause steam to enter the feed system, while low liquid levels may lead to overheating and damage to the heater tube bundle. In this study, the stacking ensemble learning model for combined data decomposition is proposed for high-precision liquid level prediction and early warning. Initially, outliers in the high-pressure heater liquid level data from the DSC system are processed. The Adaptive Local Iterative Filtering (ALIF) algorithm is used for the first data decomposition, followed by Empirical Mode Decomposition (EMD) for a second decomposition. Time-domain features such as summation, maximum value, skewness, and peak value are extracted to construct reconstructed data. Random Forest (RF) reduces the dimensionality of the reconstructed data. The prediction model combines Deep Belief Network (DBN), Deep Neural Networks (DNN), Light Gradient Boosting Machine (LGBM), and eXtreme Gradient Boosting (xGBoost) as base models, with Echo State Network (ESN) as the meta-learner. Finally, based on historical data, warning level values are set, and the system outputs warnings when the actual liquid level significantly deviates from the predicted value.

Characteristics of tritium, stable isotopes and chemical components in monthly precipitation at Hiroshima, Japan.

This article mainly discusses tritium concentrations in monthly precipitation at Hiroshima City during 2021. The tritium concentrations, which were measured with a low background liquid scintillation counter, fluctuated from 0.16 to 0.78BqL-1. Additionally, hydrogen and oxygen stable isotopes and ionic species were measured in order to characterize precipitation, and their trends including tritium concentrations were compared with data collected in other regions of Japan in previous studies. Although the results showed the characteristics of precipitation were similar to those observed in the other regions, the tritium concentrations were found to be contrary to behavior expected from the latitude effect and some of the observed ionic components were suggested to be continental in origin. Since these results are not common at other sites in Japan, the tritium concentration in the westernmost region of Honshu, including Hiroshima City, may be influenced by Asian continental influences.

Abstract A014: A methylation state specific targeted background depletion technique for enrichment of ctDNA fraction

Abstract Liquid biopsy continues to be a focus of the cancer diagnostics industry, primarily due to the non-invasive nature of sample collection, however the low levels of circulating tumor DNA (ctDNA) remain a challenge. Methylation has emerged as a promising biomarker for detecting ctDNA, yet detecting the cancerous signal in an excess of non-cancerous, unmethylated cfDNA in the background has been proven difficult. Harbinger Health has developed a novel method that depletes unmethylated background at the CpG-level from specific genomic regions of interest, resulting in an enrichment of the ctDNA fraction. We developed a background cfDNA depletion method that utilizes the endonuclease activity and the specificity of CRISPR/Cas12a to remove unmethylated DNA fragments at ctDNA methylation biomarker sites. First, we identified cancer-informative regions that showed consistent contiguous elevated methylation states in cancer compared to normal samples. We then designed guide RNAs that specifically bind and cut unmethylated CpG sites within the target regions. Cas depletion of bisulfite-converted DNA enriches cancer informative signal for bioanalysis. To test validity of our Cas complex designs, we created model samples that mimic fully unmethylated and fully methylated species. We spiked these cfDNA models into a background of genomic DNA from 5% to 0.01%. In triplicate, we examined cutting efficiency, multiplexing and specificity of Cas to unmethylated species of model DNA. Results were assessed using qPCR by comparing differences in Ct with and without Cas treatment. Additionally, we applied this depletion step during our library preparation process to show utility in methylation analysis of low tumor content liquid biopsy samples. Using both the model sample dilution series and bisulfite converted cfDNA samples, which represent a range of cancerous and background methylation signal, we deplete unmethylated targets using Cas prior to indexing PCR. This rendered unmethylated targets non-amplifiable, removing them from analysis. Results were assessed using both qPCR and sequencing data, such as methylated read counts over the target region. We demonstrated our analytical approach efficiently depletes non-cancer cfDNA by on average 9-fold, which increases the fraction of ctDNA signal and can be multiplexed. This background signal depletion driven by CRISPR is sensitive and specific, maintaining methylated DNA signal detection down to 0.01% at inputs of 10ng DNA. Our Cas-mediated depletion of background signal method has proven useful for enriching rare methylated fragments over background by improving the signal to noise ratio. This technique is novel by harnessing the specificity of CRISPR to target DNA in both a sequence and methylation state specific manner. The depletion of precise methylation states at the CpG-level make it suitable for use in multiple bioassays. Citation Format: Caitlin Gilley, Miguel Williams, Emily Neaga, Sarah Falotico, Kade Pettie, Anthony Shuber. A methylation state specific targeted background depletion technique for enrichment of ctDNA fraction [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A014.

Three-phase CFD-DEM study on the hydrodynamics of a riser system with liquid injection

Riser reactors are frequently applied in the process industry for highly important catalytic processes. In this work, a computational fluid dynamics- discrete element method (CFD-DEM) for a riser with liquid injection was developed. This model treats the gas as a continuous phase whereas the liquid droplets and catalyst particles are treated as discrete elements. The presence of droplets causes particles to be wet, which is taken into account via coverage models of the particles. In addition, the liquid on the particles will change the collision behavior, which is included using an energy balance approach. This CFD-DEM study is conducted simulating a lab-scale pseudo-2D riser. Based on the comparison, the assumption of fully covered particles results in a significant increase in the solids holdup and clustering behavior of the riser which, especially at the low liquid flow rate, results in an over-prediction. The partial coverage simulations show that only half of the particles are covered, which has a major effect on the collisions.

Comparative Metabolomics to Unravel the Biochemical Mechanism Associated with Rancidity in Pearl Millet (Pennisetum glaucum L.).

Despite being a highly nutritious and resilient cereal, pearl millet is not popular among consumers and food industries due to the short shelf-life of flour attributed to rapid rancidity development. The biochemical mechanism underlying rancidity, a complex and quantitative trait, needs to be better understood. The present study aims to elucidate the differential accumulation of metabolites in pearl millet that impact the rancidity process. Metabolite profiling was conducted on ten pearl millet genotypes with varying levels of rancidity-comprising high, low, and medium rancid genotypes-utilizing liquid chromatography and high-resolution mass spectrometry (LC-HRMS) at different accelerated ageing conditions. Through non-targeted metabolomic analysis, crucial metabolites associated with rancidity were identified across various biochemical pathways, including fatty acids, glycerophospholipids, sphingolipids, glycerol lipids, flavonoids, alkaloids, and terpenoids. Notably, metabolites such as fatty aldehydes, fatty alcohols, fatty esters, fatty acyls, fatty esters, and fatty amides were significantly elevated in high rancid genotypes, indicating their involvement in the rancidity process. These fatty acids-related metabolites further break down into saturated and unsaturated fatty acids. Four key fatty acids-stearic, palmitic, linoleic and linolenic acid-were quantified in the ten pearl millet genotypes, confirming their role in rancidity development. This investigation promises novel insights into utilizing metabolomics to understand the biochemical processes and facilitate precision breeding for developing low-rancidity pearl millet lines.

Dynamic Response and Damage Analysis of a Large Steel Tank Impacted by an Explosive Fragment

Abstract The fragments generated by explosions of storage tanks in chemical industrial parks may cause perforations or dents in adjacent tanks and trigger a domino effect. This paper determined reasonable fragment parameters based on the statistical laws of accidents and empirical formulas. The dynamic response process of large steel tanks impacted by fragments was simulated with ls-dyna. The typical impact process and results were analyzed in detail, and the damage laws of the tanks were discussed under various filling coefficients, volumes, fragment velocities, and impact angles. The results indicate that the inertial resistance of the inner liquid shortens the impact duration. Multiple collisions occur between the fragment and tank during impact, and the impact process involves three stages: initial collision, crushing and collision, and separation flight. The impact center displacement shows a fast and then slow reduction trend as the liquid level height increases, and the damage to the tank is negatively correlated with the liquid level height. The damage is lower when the tank volume is larger in an empty tank or at a high liquid level, while the damage instead increases when the volume exceeds 5000 m3 at a low liquid level. The peak impact force of the end-cap fragment is greatest when frontal impact occurs. Fragment flipping and curling occur at 45 deg and 90 deg impact, respectively. As the vertical impact angle increases from 0 deg to 90 deg, the fragment impact mode changes from initial frontal impact to flip detachment and finally to curling deformation.

EFFECT OF FUNDING STRUCTURE AND LIQUIDITY ON THE FINANCIAL PERFORMANCE OF THE SUGAR INDUSTRY IN KENYA

<p>The main objective of this study was to establish the effect of liquidity on the financial performance of the sugar industry in Kenya. The correlation between financial performance and liquidity in the Kenyan sugar industry is significant, ensuring the sector can meet immediate obligations and maintain smooth operations. Low liquidity can disrupt profitability and long-term stability, while high liquidity improves operational efficiency. Applying Stockholder and Liquidity Preference Theories to guide the study while employing correlational research design on a target population of 16 sugar companies operational in Kenya, sampled for 9 sugar companies, a total of 324 secondary data points from 2014 to 2022 were collected. Data was collected on the cost of the current ratio, acid test ratio, and economic value added, all derived from financial statements and cash flows. The results revealed a significant and positive relationship between liquidity and Economic value added (coefficient 0.939539, p=0.000<0.05); implying that liquidity has a significant relationship with economic value added. The findings are relevant for investors, policymakers, and factory managers. The study recommends that factory managers and policymakers ensure healthy liquidity within the sugar industries.</p><p> </p><p><strong>JEL: </strong>M41, G30, G32</p><p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/soc/0735/a.php" alt="Hit counter" /></p>

A microwave permittivity sensor on a Mach–Zehnder Interferometer of: Spoof surface plasmon polariton waveguides

A microwave Mach–Zehnder Interferometer (MZI) sensor for the permittivity characterization of liquids is presented in this paper. Two spoof surface plasmon polariton (SSPP) waveguide transmission lines (TLs) composed of compact spiral units is utilized in a differential architecture. Loading a dielectric material on the sensing arm induces a phase difference between the two arms, leading to periodic interference dips on the transmission curve. The spectral positions and magnitudes of these dips change with different dielectric materials. Due to the nonlinear dispersion characteristics of the SSPP TL, the proposed SSPP-based MZI sensor achieves improved sensitivity compared with microstrip-based MZI sensor. To validate the sensor’s performance, six different oil samples and a set of adulterated oils were measured, incorporating a polydimethylsiloxane (PDMS) channel on the sensing arm. The variations in the spectral position and magnitude of the interference dip centered at 3.2 GHz are employed to determine the dielectric constants and loss tangents of the tested oils. The sensitivity in measuring the dielectric constant is 3.61 %. The maximum errors for measuring the dielectric constant and the loss tangent are 4.3 % and 6.7 %, respectively. Compared to other sensors for liquid oil detection, the proposed sensor provides a relatively high sensitivity while maintaining a low liquid volume, making it a promising candidate for permittivity measurements of liquid analytes and solid materials with similar dielectric constants.

Cyclic flow cut-off characteristics of gas-liquid two-phase flow in pipeline-riser system and prediction of its occurring condition

In offshore oil and gas fields, the prediction of gas-liquid two-phase flow pattern is of great importance for the design and operation of pipeline-riser systems. However, no special attention was put on the mechanism of periodic flow cut-off at the riser outlet, which is an inherent characteristic of certain flow patterns directly related to operation safety, in the study of flow pattern transition. In this study, differential pressure signals are used to explore the internal correlation between the flow cut-off of gas and/or liquid phase at the riser bottom and the riser outlet. The flow patterns are classified based on continuous flow or flow cut-off at the riser outlet. Then, the flow pattern transition mechanisms are studied from the view of the condition under which flow cut-off will appear. At high gas and low liquid velocities, the mechanism can be explained by a conventional theory; while at high gas and high liquid velocities, dissipation of hydrodynamic slugs becomes the major reason for flow pattern transition; and a unified model is introduced to predict the dissipation. At low gas and high liquid velocities, the condition for gas-liquid eruption can still describe the flow pattern transition, but it is modified by the slug dissipation model. At higher pressure, the lasting time of gas cut-off at the riser elbow becomes shorter, and a threshold can be set to decide whether it can be ignored. The predicted results are in good agreement with the flow pattern maps under different pipeline structures and fluid properties, and the reason why flow cut-off disappears in the experimental loop at high pressure of 10 MPa is successfully explained.

Cu–Cu joint with great strength using In/Sn–58Bi hybrid soldering at low temperature (90 °C)

This study investigates Cu single-sided solder joints using hybrid soldering (In + Sn58Bi) at reflow temperatures ranging from 80 to 130 °C. The wetting angles of 27° at 90 °C and 22° at 130 °C demonstrated good wettability. The hybrid solders were composed of γ-In(Sn, Bi) and Bi(In, Sn)2 phases, forming Cu6(In, Sn)5 interfacial intermetallic compounds (IMCs). Thermodynamic calculations proved that the hybrid soldering possessed a low liquid temperature of 86.8 ° C, making it suitable for low-temperature applications. The hybrid solders demonstrated notable mechanical performance, with microhardness values exceeding 10 HV—higher than Sn–52In solder (6 HV). Sandwich hybrid-solder joints, reflowed at 90 and 130 ° C, outperformed Sn–52In soldering strength (30.1 and 35.5 MPa) by over 135% and 175%. Additionally, the hybrid solder contains only 41.9 wt% In, lower than Sn–52In, reducing material costs. This study reveals the hybrid solder system offers a promising low-cost and good-strength solution for low-temperature soldering applications.

Optical anisotropy and surface phases of cholesterol derivative monolayer at air–water interface

Cholesterol and its derivatives play crucial roles in regulating processes of biological membranes. Langmuir monolayer can mimic a bio-membrane which can be used to investigate the molecular interaction governing the important physical phenomena. The cholesterol derivative exhibiting mesophases (CHLC molecules) was synthesized and spread at the air–water (A/W) interface to investigate the surface behavior. The monolayer exhibited a variety of surface phases such as gas, liquid expanded (LE), low density liquid like (L1) and liquid condensed (L2) phases. Treating the CHLC molecules to be rod-like, the average tilt of the molecules with respect to the surface normal in these phases are found to be different. The tilt angle decreases systematically from LE to L2 phase. The optical anisotropy of the ultrathin Langmuir-Blodgett (LB) films of CHLC molecules in these phases was measured using the surface plasmon resonance (SPR) spectroscopy. The high tilted molecules in the ultrathin LB film displayed a high value of optical anisotropy. The ultrathin film of CHLC molecules at different interfaces was investigated using Brewster angle microscopy, X-ray reflectivity (XRR), SPR spectroscopy and atomic force microscopy. This study is useful for the systems where the physical phenomena are governed by tilt of the molecules.

Forecasting ETF Performance: A Comparative Study of Deep Learning Models and the Fama-French Three-Factor Model

The global financial landscape has witnessed a significant shift towards Exchange-Traded Funds (ETFs), with their market capitalization surpassing USD 10 trillion in 2023, due to advantages such as low management fees, high liquidity, and broad market exposure. As ETFs become increasingly central to investment strategies, accurately forecasting their performance has become crucial. This study addresses this need by comparing the efficacy of deep learning models against the traditional Fama-French three-factor model in predicting daily ETF returns. The methodology employs eight artificial neural network architectures, including ANN, LSTM, GRU, CNN, and their variants, implemented in Python and applied to data ranging from 2010 to 2020, while also exploring the impact of additional factors on forecast accuracy. Empirical results reveal that LSTM and the Fama-French three-factor model exhibit a superior performance in ETF return prediction. This study contributes to the literature on financial forecasting and offers practical insights into investment decision making. By leveraging advanced artificial intelligence techniques, this study aims to enhance the toolkit available for ETF performance analysis, potentially improving investment strategies in this dynamic market segment.

Thermodynamics, phase diagram, structure and anomalies of supercooled aqueous solutions of trehalose: A molecular dynamics study

We perform molecular dynamics simulations of supercooled solutions of trehalose in TIP4P/2005 water, with concentrations of 20 and 40 wt% (weight percentage) in trehalose, a disaccharide often used in cryopreserving solutions. We analyze the thermodynamics and the structure of these solutions. From the isochores we find that in the 20 wt% solution the temperature of maximum density (TMD) line is still present and it is shifted to lower temperatures with respect to that of pure water. We also find that the Widom line and the liquid-liquid critical point (LLCP) are still present for this concentration and we estimate the position of the LLCP to be shifted at lower temperatures and slightly lower pressures with respect to that of pure water. In the 40 wt% solution we find that the TMD line still persists, but the region of density anomaly shrinks. No LLCP is observed down to the lowest temperature investigated, and maxima of the isothermal compressibility, used as proxy for the Widom line, become weaker. The water oxygen - water oxygen radial distribution functions keep on showing the typical distinction between high density and low density liquid found in pure water, but at low temperatures the presence of trehalose appears to favor the high density phase of water more than in pure water. The number of water molecules of the solvation shell confirms this picture.

Technology and Research on Improving Oil Recovery by Volume Fracturing with Phase Change Permeability in Ultra-low Permeability Reservoirs

Abstract The conventional water injection development production wells in ultra-low permeability reservoirs have low efficiency, low production and low liquid content, and poor economic benefits. Traditional water drive development techniques are difficult to adapt to the requirements of economically effective development in ultra-low permeability reservoirs. Therefore, it is urgent to adjust development ideas and transform water injection development methods. A major development experiment was carried out in the Y284 area of Huaqing Oilfield to transform the water injection development method. Based on the mechanism of reverse osmosis flooding in oil recovery wells, this article uses dynamic monitoring technologies such as downhole microseismic to achieve three-dimensional reservoir transformation, and establishes a large-scale fracturing technology of “collaborative permeability flooding, volume fracturing, and multi-stage temporary plugging” for reverse osmosis wells in ultra-low permeability reservoirs. Research has shown that large-scale fracturing technology for water injection wells can improve single well oil recovery speed by increasing the complexity of fracture networks. The important factors affecting the effectiveness of water injection wells include reservoir properties, fracturing transformation scale, cumulative water injection volume, remaining oil distribution, and heterogeneity of aquifers. At the same time, the construction parameters of large-scale volume fracturing for water injection wells, namely 140-170m, are quantitatively determined based on the actual situation of the mining field ³ The amount of sand added, a sand ratio of 17-22%, and a large displacement of 8-10m3/min, 1400-2000m ³ The amount of liquid entering the ground can most effectively achieve the conditions for reservoir transformation. The conclusion is that large-scale fracturing technology for conversion wells provides technical support for volume fracturing and optimization design of fracturing parameters for low production wells in ultra-low permeability reservoirs, and can provide guidance and reference for the efficient development of other similar ultra-low permeability reservoirs.

Development of the market of digital financial assets in the context of ensuring financial sovereignty of Russia

Currently, in the context of limited external funding, the issues of forming the financial sovereignty of the country are becoming the subject of scientific discourse among Russian economists. The introduction of digital financial assets (DFA) into business practice and their legislative recognition largely ensures the expansion of investment opportunities for economic entities, which will contribute to the end of the stagnant macroeconomic shock of the period of 2021–2024. The work covers solving such scientific problems as clarifying the essential nature of DFA and developing their classification; assessing the process of functioning of the investment market based on the use of digital financial instruments; identifying key limitations in the functioning of the basic institutions regulating the DFA circulation. The authors proposed a clarified formulation of the economic category of digital financial assets, taking into account the peculiarities of its essential nature. An analysis of the functioning of the domestic DFA market is carried out. Among the factors hindering the development of the DFA market, its fragmentation, low liquidity, and weak institutional regulation of the issue and circulation of DFA are highlighted. The authors emphasize the positive effect of the development of the digital infrastructure of the market, in particular, the increase in the number of investment platforms licensed by the Bank of Russia, the reduction of costs of access to them, the development of a market-making system in the secondary market of digital financial assets. The authors believe that the leveling of the contradictions of the investment market should occur due to the improvement of the institutional environment in the field of strengthening control over transactions with digital financial assets, as well as ensuring their mandatory registration, which is absent at the present stage. The development of the domestic market of digital financial assets has significant potential due to, firstly, the desire of economic entities to replace traditional financial instruments with digital ones, which allow reducing significantly transaction and transformation costs; secondly, the expansion of investment opportunities for economic actors through the use of digital platforms and other elements of the digital ecosystem for the purpose of business development; thirdly, the transformation of the traditional business model, which provides for the transition from vertical interaction of entities to a network form of coordination of economic agents using decentralized financial instruments in their activities.

Site selection for Proposed Construction Using the Electrical Resistivity Method and Some Geotechnical Tests of Soil At Al-Nahrawan Area, Baghdad, Iraq

The study site represents an investigation of a proposed construction site in Baghdad City, in the Al-Nahrawan area, using 2D electrical resistivity and some geotechnical tests for soil samples. A Wenner-Schlumberger configuration was used for 4 parallel lines, each line 120 m long, with 1m spacing between electrodes. Interpretation is made by RES2DINV software. The results showed areas with relatively high resistivity caused by mud cracks and low- resistivity caused by water content (wet soil). The groundwater depth ranges from 5.5 to 5.7 m; these values were matched by comparing with nearby wells using a sounder device. Soil samples from different depths ranging from 0.5 to 4 m were analysed, and the samples consisted mainly of clay > 88% with low liquid and plastic limits >50 (USCS). It is classified as CL, which means Low plasticity. The electric method and laboratory tests were effective in identifying the subsurface image.

The current state of industrial fishing in the Central Federal District of Russia and prospects for its development

The article considers a brief history of fishing and its current state in the reservoirs of the Central Federal District. For reservoirs and lakes of the Upper Volga and Oka basins, the dynamics of fish catch on average over the decades from the 60s of the twentieth century to 2023 are presented, and the dynamics of the species composition of industrial catches in these reservoirs is analyzed. The reasons that led to a decrease in the intensity of fishing or its closure in modern market conditions are considered. The description of the features of industrial fishing is presented by groups of reservoirs, depending on the area and volume of fish caught. The first group includes the large Upper Volga reservoirs (Rybinsk, Gorkovskoye), the average annual total catch in each of which exceeds 500 tons. The second group considers the reservoirs of the Upper Volga basin, in which 200–500 tons per year were caught during the Soviet period, and currently the volume of catch has decreased by an order of magnitude or fishing has stopped altogether. The third group of reservoirs includes small reservoirs of the Vazuz hydrotechnical system and cooling reservoirs of energy facilities, in which the volume of catch is currently less than 20 tons, but during their fishery development in the 70–80-ies of the twentieth century in the mode of «pasture fish farming» annual catches reached 100 tons. It has been established that the volume of industrial catch in most of the water bodies of the region has decreased over the two decades of the 21st century. The decline of industrial fishing in the Central Federal District is explained by a complex of socio-economic factors, the main of which is its unprofitability in market conditions, due to the low liquidity of most fishing facilities that form the basis of catch, the lack of the necessary number of catch processing enterprises and the cessation of subsidizing fish harvesters. The forecast of the further state of industrial fishing in the reservoirs of Central Russia is given.

Two state model for the ML-BOP potential

The coarse-grained machine-learning derived ML-BOP model [Chan et al., Nature Commun. 10, 379 (2019)] provides a monoatomic representation of the water-water interaction potential in which orientational interactions are included as three-body contributions. Despite its simplicity, the model reproduces the phase diagram of water and its anomalies. Here, we show that a two-state Gibbs free energy expression – fitted simultaneously on the temperature and pressure dependence of the density and internal energy – predicts the existence of a liquid–liquid critical point, with critical parameters consistent with previous estimates. We also show that in this model: (i) while the low density liquid is pre-empted by crystal nucleation, the high-density liquid and its spinodal are accessible in numerical studies down to 100 K; (ii) crystallisation requires the presence of a local low density region. Thus, for densities larger than the critical density, spinodal decomposition (or nucleation of the low-density liquid) is a pre-requisite for ice nucleation.

Surfactant-mediated enhancement of liquid permeability in scots pine wood

Scots pine (Pinus sylvestris L.) is a widely-used wood species in construction and exterior applications. However, inherently low liquid permeability of wood presents substantial challenges to processing efficiency. In order to improve the liquid permeability in Scots pine, the effect of two different surfactants including dodecyl dimethyl ammonium chloride (DDAC) and primary alcobol ethoxylate (JFC-U) were investigated in this study. The mechanism was unveiled by microscopic observation, chemical analysis of extractive composition, and molecular dynamics (MD) simulations. The results demonstrated that both surfactants increased the liquid absorption in Scots pine by 14.7–46.3 % within 0.5 h. This effect was mainly attributed to the surfactants' capability to enhance surface wetting and dissolve extractives deposited on pit membrane in Scots pine wood. DDAC outperformed JFC-U in dissolving extractives. The MD simulations between DDAC and stearic acid (a representative extractive) illustrated that DDAC could envelope stearic acid molecules and form micellar structures through the strong intermolecular forces between them. These findings provide valuable insights into the effect and mechanisms by which surfactants enhance liquid permeability in extractive-rich wood, therefore, to support the development of efficient wood treatment technologies.

Modeling of high-pressure transient gas-liquid flow in M-shaped jumpers of subsea gas production systems

Two-phase flow with low liquid loads is common in high-pressure natural gas offshore gathering and transmission pipelines. During gas production slowdowns or shutdowns, an accumulation of liquid in the lower sections of subsea pipelines may occur. This phenomenon is observed in jumpers that connect different units in deep-water subsea gas production facilities. The displacement of the accumulated liquid during production ramp-up induces temporal variations in pressure drop across the jumper and forces on its elbows, resulting in flow-induced vibrations (FIV) that pose potential risks to the structural integrity of the jumper. To bridge the gap between laboratory experiments and field conditions, transient 3D numerical simulations were conducted using the OpenFOAM software. These simulations facilitated the development of a mechanistic model to elucidate the factors contributing to increased pressure and forces during the liquid purging process. The study examined the influence of gas pressure level, pipe diameter, initially accumulated liquid amount, liquid properties, and gas mass flow rate on the transient pressure drop and the forces acting on the jumper's elbows. The critical gas production rate required for complete liquid removal of the accumulated liquid was determined, and scaling rules were proposed to predict the effects of gas pressure and pipe diameter on this critical value. The dominant frequencies of pressure and force fluctuations were identified, with low-pressure systems exhibiting frequencies associated with two-phase flow phenomena and high-pressure systems showing frequencies attributed to acoustic waves.