Moisture Intrusion Research Articles

Asymmetric phthalocyanine-based hole-transporting materials: evaluating the role of heterocyclic units and PMMA additive.

Two novel asymmetric phthalocyanine derivatives, ZnPc-1 and ZnPc-2, are synthesized to enhance charge transfer properties and mitigate deep-level traps on the perovskite surface using electron-rich nitrogen atoms. PSCs with ZnPc-1 and ZnPc-2 as hole-transporting materials (HTMs) achieved power conversion efficiencies (PCEs) of 12.11% and 8.98%, respectively. Incorporating a small amount of PMMA into the HTM solution significantly improved performance, resulting in PCEs of 16.2% and 12.5% for ZnPc-1 and ZnPc-2, respectively. The addition of PMMA enhances conductivity and prevents moisture intrusion, boosting both the efficiency and stability of PSCs.

The impact of coupling a dynamic ocean in the Hurricane Analysis and Forecast System

Coupling a three-dimensional ocean circulation model to an atmospheric model can significantly improve forecasting of tropical cyclones (TCs). This is particularly true of forecasts for TC intensity (maximum sustained surface wind and minimum central pressure), but also for structure (e.g., surface wind-field sizes). This study seeks to explore the physical mechanisms by which a dynamic ocean influences TC evolution, using an operational TC model. The authors evaluated impacts of ocean-coupling on TC intensity and structure forecasts from NOAA’s Hurricane Analysis and Forecast System v1.0 B (HFSB), which became operational at the NOAA National Weather Service in 2023. The study compared existing HFSB coupled simulations with simulations using an identical model configuration in which the dynamic ocean coupling was replaced by a simple diurnally varying sea surface temperature model. The authors analyzed TCs of interest from the 2020–2022 Atlantic hurricane seasons, selecting forecast cycles with small coupled track-forecast errors for detailed analysis. The results show the link between the dynamic, coupled ocean response to TCs and coincident TC structural changes directly related to changing intensity and surface wind-field size. These results show the importance of coupling in forecasting slower-moving TCs and those with larger surface wind fields. However, there are unexpected instances where coupling impacts the near-TC atmospheric environment (e.g., mid-level moisture intrusion), ultimately affecting intensity forecasts. These results suggest that, even for more rapidly moving and smaller TCs, the influence of the ocean response to the wind field in the near-TC atmospheric environment is important for TC forecasting. The authors also examined cases where coupling degrades forecast performance. Statistical comparisons of coupled versus uncoupled HFSB further show an interesting tendency: high biases in peak surface winds for the uncoupled forecasts contrast with corresponding low biases, contrary to expectations, in coupled forecasts; the coupled forecasts also show a significant negative bias in the radii of 34 kt winds relative to National Hurricane Center best track estimates. By contrast, coupled forecasts show very small bias in minimum central pressure compared with a strong negative bias in uncoupled. Possible explanations for these discrepancies are discussed. The ultimate goal of this work will be to enable better evaluation and forecast improvement of TC models in future work.

F for Fantastic: Fostering Stability and Efficiency in Perovskite Solar Cells via Comb-Like Perfluoroalkyl-g-Polyethylenimine Additive.

Additive engineering has emerged as a promising strategy to address the inherent instability challenges of perovskite solar cells (PSCs) in the pursuit of commercial viability. However, achieving multifunctionality using a singular additive remains a considerable challenge. In this study, a novel comb-like multifunctional perfluoroalkyl-g-polyethylenimmonium iodide (FPEI·HI) as additives to the PbI2 precursor solution to facilitate the formation of high-quality and water-resistant perovskite films is presented. FPEI·HI establishes robust interactions with both formamidinium iodide (FAI) and PbI2, mediated by hydrogen bonding and Lewis acid-base interactions. These interactions play a pivotal role in simultaneously passivating negative and positive charged defects within the perovskite structure. Furthermore, the inclusion of perfluoroalkyl chains serves as resilience against moisture intrusion. As a consequence of these effects, a notably high device efficiency of 24.29% is achieved, demonstrating comprehensive improvement in various photovoltaic parameters compared to the control device (22.51%). Notably, unencapsulated devices exhibit remarkable stability in high-humidity environments, retaining 90% of their initial efficiency even after 2500h of storage. This work underscores the efficacy of FPEI·HI as a critical enabler for enhancing the stability and efficiency of perovskite solar cells, marking a significant stride toward their commercialization.

The Application of Infrared Thermography for Enhancing Maintenance in Public University

A university’s main function is to produce quality graduates, and in doing so, university buildings do play significant roles and are vital assets and resources. Hence, to prolong a university building lifecycle to ensure all university activities to continue performing at an optimum level, building maintenance management is central. Eventhough previous studies have been conducted in this area, university buildings maintenance is still viewed as insignificant. The research about utilization of infrared thermography in term of maintenance in public universities is still lacking. The objective of this research was to provide recommendations for areas within the public universities that can benefit from the application of infrared thermography to enhance maintenance. The research method used in this research was a qualitative method. Three public universities that were established for more than 50 years were chosen as case studies. The data was collected through narrative review and then analyzed. The findings highlighted the benefits of implementing infrared thermography in older building maintenance within public universities, particularly in improving energy efficiency and identifying hidden issues such as moisture intrusion and structural defects. The study emphasized the importance of timely maintenance actions based on infrared thermography assessments to reduce energy consumption and apply predictive maintenance strategies. By conducting in-depth analyses at three established public universities in Malaysia, the researchers demonstrate the effectiveness of infrared thermography in enhancing maintenance practices and prolonging the lifecycle of university buildings.

Establishing the Taxonomy of Building Defects Triggered by Moisture Intrusion and Dampness

Establishing the Taxonomy of Building Defects Triggered by Moisture Intrusion and Dampness

Hygrothermal aging mechanism of epoxy composites used for medium-frequency transformers

The integration of medium-frequency transformer design and the harsh service environment raise higher demands for the medium-frequency insulation performance of epoxy composites. As epoxy composite's frequency response characteristics and sensitivity to moisture intrusion are still unknown, its application as the insulation materials of medium-frequency transformers under hygrothermal conditions is limited. This paper investigates the mechanism of moisture intrusion damage to the molecular structure of the epoxy resin matrix and its cross-linking points with the curing agent. The regularity of medium-frequency insulation performance degradation of epoxy composites after hygrothermal aging is studied. Results indicate that after 40 days of hygrothermal aging, moisture together with high temperature damaged the main chain of the epoxy resin and its cross-linking points with the curing agent, resulting in a 23 °C decrease in the glass transition temperature and an 82 % decrease in cross-linking density of the epoxy composite. Moisture ionization and the increase of carriers due to epoxy resin hydrolysis lead to an increase in the amount of space charge. The temperature rise caused by dipole steering polarization facilitates the formation of internal conductive pathways in the epoxy composite, resulting in a 73 % decrease in the medium-frequency breakdown strength and a four-order magnitude decrease in the medium-frequency volume resistivity of the epoxy composite. This study can guide the insulation design of high-reliability medium-frequency transformers.

Study on the fracture behavior in clayey geomaterials under moisture diffusion by phase field modeling

Clayey geomaterials are prone to cracking under changing moisture conditions, which substantially compromises their engineering properties. When moisture intrusion and boundary constraints act in tandem on geomaterials, the relevance of multi-physics field processes to complex cracking phenomena remains underexplored. To provide deeper insight into the effect of moisture transport on the cracking behavior of clayey geomaterials, a theoretical model for moisture-induced fracture is proposed. The model combines moisture diffusion, volume deformation dependent on moisture conditions, and phase field fracture, and is solved using the finite element method with a user-defined element subroutine. The developed subroutine is applied to simulate soil desiccation experiments and mudstone water absorption tests. The results reveal that moisture gradients induce non-uniform expansion or shrinkage within the clayey geomaterials. The neighboring geomaterial particles mutually constrain these deformations, resulting in an internal stress field that serves as the primary cause of cracking. Stability and sensitivity analyses validate the reliability of the numerical framework. The proposed model can effectively simulate crack initiation, extension, and convergence during humidification or desiccation processes in both two and three dimensions. This study charts a feasible path for numerical simulation and mechanical mechanism exploration of cracking behaviors in clayey geomaterials during water migration.

Synoptic Moisture Intrusion Provided Heavy Isotope Precipitations in Inland Antarctica During the Last Glacial Maximum

AbstractStable water isotopes in inland Antarctic ice cores are powerful paleoclimate proxies; however, their relationship with dynamical atmospheric circulations remains controversial. Using a water isotope climate model (MIROC5‐iso), we assessed the influence of the Last Glacial Maximum (LGM; ∼21,000 years ago) sea surface temperatures (SST) and sea ice (SIC) on Antarctic precipitation isotopes (δ18Op) through atmospheric circulation. The results revealed that the synoptic circulation mostly maintained southward moisture transport, reaching inland Antarctica. The steepened meridional SST gradient in the mid‐latitudes increased δ18Op in inland Antarctica with the enhanced baroclinic instability and synoptic moisture transport. In contrast, expanded SIC distribution decreased δ18Op over Antarctica by enhanced preferential removal of heavy isotopes during vapor transport due to the increased transport distance and enhanced surface cooling. These findings propose to use Antarctic ice cores to describe the southern hemisphere atmospheric circulation, represented by the westerly jets, during the LGM and other past climates.

Multifunctional Interface Modification Enables Efficient and Stable HTL-Free Carbon-Electroded CsPbI2Br Perovskite Solar Cells.

In recent years, hole transport layer-free all-inorganic CsPbI2Br carbon-electroded perovskite solar cells (C-PSCs) have garnered significant attention due to a trade-off between stability and photovoltaic performance. However, there are inevitably many defects generated at the surfaces or grain boundaries of CsPbI2Br perovskite films, which will serve as carrier non-radiative recombination centers, and CsPbI2Br perovskite films are sensitive to water molecules to degrade, together with energy level mismatch between CsPbI2Br perovskite and carbon electrodes. Herein, 1-benzyl-3-methylimidazolium hexafluorophosphate (1-B-3-MIMPF6), an imidazolium-based ionic liquid simultaneously containing benzene ring and fluorine atoms, was introduced for the modification of the perovskite/carbon interface. The results showed that it could effectively reduce defects, enhance carrier transfer, mitigate carrier non-radiative recombination, facilitate energy alignment, and block moisture intrusion. Therefore, the photovoltaic performance of the modified PSCs with ITO/SnO2/CsPbI2Br/1-B-3-MIMPF6/carbon architecture has been boosted with a champion power conversion efficiency (PCE) of 13.47 %, open circuit voltage of 1.20 V, short circuit current density of 14.69 mA/cm2, and fill factor of 76 %. Moreover, the unencapsulated modified devices exhibited an improved stability and the PCE maintained 78 % of their initial PCE after 24 h storage at room temperature in a 30 %-35 % humidity environment, whereas that of the pristine devices dropped to almost zero.

Challenges in Simulating Prevailing Fog Types Over Urban Region of Delhi

AbstractAccurately predicting fog is challenging due to interplay of myriad processes in its formation and high spatiotemporal variability. This study compares the performance of the Weather Research and Forecasting model with control (CNTL‐WRF) and assimilated fine‐grid (HRLDAS‐WRF) soil fields in the Ingo‐Gangetic Plain (IGP) over a 2‐years winter period (2019–2020 and 2020–2021). Results show HRLDAS‐WRF enhances accuracy in representing surface fog's heterogeneity and lifecycle across the IGP, demonstrating a spatial skill improvement of approximately 18% with a Fraction Skill Score of 0.44, compared to CNTL‐WRF's (0.36). Employing fog classification algorithm identifies 25 dense fog episodes (Vis < 500 m) over Delhi's urban boundary layer, including 14 radiation (RAD), 5 cloud‐base lowering (CBL), 3 advection + radiation (ADV + RAD), and 3 evaporation (EVA) episodes. CNTL‐WRF predicts 20 episodes but misses five due to a dry bias in the initial moisture conditions. However, HRLDAS‐WRF demonstrates limited vertical fog growth in various occurrences, highlighting the crucial role of fine‐gridded soil states for enhanced land‐surface feedback. Detailed analysis shows a 40% reduction in mean onset error for RAD fog occurrences in HRLDAS‐WRF when compared to CNTL‐WRF. In CBL fog episodes, both models exhibit significant radiative cooling and inversion before fog onset, leading to inaccurate predictions as RAD fog. Similarly, forecasting the abrupt development of ADV + RAD fog episodes is challenging as models struggle to replicate moisture intrusion over radiatively cooled surfaces in windy conditions. Predicting EVA fog, forms within an hour after sunrise, remains difficult due to the current model parameterization that rapidly dissipates fog soon after sunrise.

Extreme events of snow grain size increase in East Antarctica and their relationship with meteorological conditions

Abstract. This study explores the seasonal variations in snow grain size on the East Antarctic Plateau, where dry metamorphism occurs, by using microwave radiometer observations from 2000 to 2022. Local meteorological conditions and large-scale atmospheric phenomena have been considered in order to explain some peculiar changes in the snow grains. We find that the highest ice divide is the region with the largest grain size in the summer, mainly because the wind speed is low. Moreover, some extreme grain size values with respect to the average (over +3σ) were identified. In these cases, the ERA5 reanalysis revealed a high-pressure blocking close to the onsets of the summer increase in the grain size. It channels moisture intrusions from the mid-latitudes, through atmospheric rivers that cause major snowfall events over the plateau. If conditions of weak wind and low temperature occur during the following weeks, dry snow metamorphism is facilitated, leading to grain growth. This determines anomalous high maximums of the snow grain size at the end of summer. These phenomena confirm the importance of moisture intrusion events in East Antarctica and their impact on the physical properties of the ice sheet surface, with a co-occurrence of atmospheric rivers and seasonal changes in the grain size with a significance of over 95 %.

A comprehensive evaluation method for moisture and aging state of oil-immersed paper bushings based on dielectric modulus and K-nearest neighbor algorithm

The insulation performance of oil-immersed paper bushings is prone to deteriorate, primarily due to moisture intrusion and thermal aging. The frequency domain spectroscopy (FDS) method is commonly employed to assess the insulation condition of the bushing. However, identifying and extracting relaxation polarization information from the low-frequency region of the FDS curve can be challenging, and there is little research about the condition evaluation under the combined effects of aging states and moisture content. To address this issue, this article uses the Taylor formula mathematical model to extract characteristic parameters from the dielectric modulus curve of OIP bushings and uses the KNN algorithm to achieve the evaluation of aging and moisture status. Then, the effectiveness and accuracy of the proposed method are validated on three field OIP bushings. The results demonstrate that the evaluation accuracy of the proposed method exceeds 83%, which has significant advantages compared to other classification algorithms. The innovation of this article lies in extracting new feature parameters and combining them with intelligent classification algorithms to evaluate the moisture and aging state of the bushing.

Numerical simulation of flow and heat transfer characteristics of small compact heat pipe heat exchangers for communication cabinets

In response to the current high demand for communication, additional communication base stations are being constructed, leading to more stringent heat dissipation requirements. In the past, the use of air conditioning or direct ventilation using fans to solve the heat dissipation was very effective. However, the former incurred higher input and operating costs. The latter was cost-effective but posed risks such as moisture and dust intrusion, short circuits, and thermal control issues inside the cabinet. This paper presents a scheme of small compact heat pipe heat exchanger (SCHPHE) for cabinet heat dissipation. The heat transfer and flow characteristics of annular fin and plate fin SCHPHEs under the same conditions are numerically simulated. The numerical simulation results are summarized and analyzed after making modifications to the design parameters. The advantages and disadvantages of the SCHPHE with annular fin and the SCHPHE with plate fin are analyzed under various parameters (fin height, fin thickness, and fin spacing) changes. Furthermore, the paper provides a prediction equation for the heat transfer capacity of the SCHPHE with variations in its specifications.

Estimating Time of Mold Growth in an Indoor Environment

Mold growth (not spores) on surfaces indicates the presence of moisture in an indoor environment at some point in time. Mold proliferation is merely the direct consequence of moisture intrusion. Direct microscopical examination is the primary method to determine if mold or other fungi have grown on a particular surface. This analysis, while generally straightforward, provides the important answer to the question of whether mold growth is present. The growth can be described as the presence of vegetative structures (hyphae or mycelium) with or without associated spores or sporulating structures.

Degradation of SMA-13 low-temperature performance under coupled dry and wet-salt corrosion

To investigate the low-temperature performance of polyester fiber-modified asphalt mixtures under the influence of dry-wet-salt corrosion coupling, six different polyester fiber content levels (0%, 0.3%, 0.35%, 0.4%, 0.45%, and 0.5% by weight of the mixture) were chosen for preparing SMA-13 asphalt mixture specimens. The Ultrasonic non-destructive testing, semi-circular bending tests, and scanning electron microscopy (SEM) were employed to evaluate the low-temperature performance of these mixtures under dry-wet-salt corrosion conditions with varying cycle numbers (0, 2, 4, 6, 8 cycles). The results of ultrasonic non-destructive testing showed that the wave velocity exhibited a trend of initial increase followed by a subsequent decrease with the increase in polyester fiber content. It reached a maximum value of 4.06 cm/us at a fiber content of 0.4%. The semi-circular bending tests (SCB) revealed that the fracture toughness of the polyester fiber asphalt mixture decreased as the number of dry-wet cycles increased. The impact of salt-dry-wet coupling > water-dry-wet coupling. Notably, after undergoing 4 cycles of water-dry-wet exposure, the overall fluctuation in specimen fracture toughness was minimal, indicating that results after four cycles could be suitable for evaluating the long-term degradation performance of asphalt mixtures under extended water-dry-wet cycling. SEM test results demonstrated that a polyester fiber content of 0.4% led to the formation of a strong fibrous network structure within the asphalt mixture. This significantly reduced moisture and salt intrusion during the dry-wet cycling process, enhancing the low-temperature crack resistance of the specimens.

Imaging of vertical surface-breaking cracks in concrete members using ultrasonic shear wave tomography

Surface-breaking cracks in concrete pose a significant threat to the durability of built structures. They create pathways for an accelerated moisture intrusion, and the transport of environmental and chemical agents such as chloride ions, which in turn, exacerbate reinforced concrete deterioration. Estimating the extent of crack propagation beneath the surface helps in determining the safety, durability and reliability of a structure. This information can be used to devise appropriate repair methodologies. Developments in Dry Point Contact (DPC)-based ultrasonic arrays have enabled the detection and localization of defects in concrete through high-resolution imaging. This work proposes the use of Half-Skip travel modes in the time-domain pulse-echo data to be deployed for imaging vertical cracks in concrete. In contrast to the standard Synthetic Aperture Focusing Technique (SAFT), which is widely used for ultrasonic imaging of concrete, the Half-Skip Total Focusing Method (HSTFM) configuration uses the target-scattered signals after a reflection from the back wall. The technique has been evaluated on both simulated and experimentally measured ultrasonic data on specimens fabricated with notches and cracks of different depths. Crack sizes were estimated by measuring the length of thresholded reflection signatures obtained in the images. The presented solution using half-skip modes serves as a supplementary technique to standard SAFT, in order to estimate the depth of surface-breaking cracks in concrete.

Study on the damage mechanism of moisture intrusion to the FRP/RPUF interface of composite cross-arms when considering the influence of temperature

Moisture is more likely to infiltrate the FRP/RPUF interface with relatively weak internal insulation of composite insulated cross-arms in humid and hot working environments, leading to interface degradation. However, the damage mechanism after water infiltration into the FRP/RPUF interface under temperature conditions remains unclear. This study conducted moisture infiltration experiments and explored the damage mechanism after moisture infiltration into the FRP/RPUF interface under the influence of temperature using molecular dynamics simulations. The moisture absorption process at the FRP/RPUF interface is divided into two stages: Fick or Langmuir moisture absorption and physical moisture absorption. During the Fick or Langmuir moisture absorption stages, increased temperature enhanced the diffusion coefficient of water molecules and accelerated the moisture absorption rate of the material. Simultaneously, the proportion of bound water to free water in the system decreased, increasing the free volume fraction within the material. As the equilibrium between bound and free water was reached, the system could accommodate more moisture, thereby increasing the saturation moisture absorption capacity of the interface material. During the physical moisture absorption stage, increased temperature accelerated the decomposition rate of the material, intensifying the degree of interface bonding failure. Simultaneously, the thermal motion of the water molecules became more vigorous, increasing the influx of moisture into the sample through interface cracks. Consequently, the moisture absorption capacity and rate of the sample increased.

A Self-Assembled 3D/0D Quasi-Core-Shell Structure as Internal Encapsulation Layer for Stable and Efficient FAPbI3 Perovskite Solar Cells and Modules.

FAPbI3 perovskites have garnered considerable interest owing to their outstanding thermal stability, along with near-theoretical bandgap and efficiency. However, their inherent phase instability presents a substantial challenge to the long-term stability of devices. Herein, this issue through a dual-strategy of self-assembly 3D/0D quasi-core-shell structure is tackled as an internal encapsulation layer, and in situ introduction of excess PbI2 for surface and grain boundary defects passivating, therefore preventing moisture intrusion into FAPbI3 perovskite films. By utilizing this method alone, not only enhances the stability of the FAPbI3 film but also effectively passivates defects and minimizes non-radiative recombination, ultimately yielding a champion device efficiency of 23.23%. Furthermore, the devices own better moisture resistance, exhibiting a T80 lifetime exceeding 3500h at 40% relative humidity (RH). Meanwhile, a 19.51% PCE of mini-module (5×5cm2) is demonstrated. This research offers valuable insights and directions for the advancement of stable and highly efficient FAPbI3 perovskite solar cells.

Innovations in Building Diagnostics and Condition Monitoring: A Comprehensive Review of Infrared Thermography Applications

Infrared thermography is a non-destructive technique that uses infrared radiation to visualize surface temperature variations. It is a versatile tool that can be used to detect a variety of problems in buildings, including insulation deficiencies, moisture intrusion, structural compromise, and electrical faults. The review paper discusses the fundamental principles of infrared thermography, the different types of infrared approaches, and the condition monitoring of buildings using infrared imaging techniques. It also discusses research showing how infrared thermography has been applied to recognize and solve different building-related problems. The article highlights the potential for infrared thermography to advance while also acknowledging its current limits. Infrared thermography is predicted to become an even more effective technique for building diagnostics with the development of more sensitive cameras and the incorporation of artificial intelligence.

Mechanical, physical and compositional effects of Meruliporia incrassata on Southern Yellow Pine

Abstract With the growing risk of fungal degradation in timber-framed structures from significant moisture intrusion events due to climate change, it is increasingly critical to develop mechanistic relationships between fungal degradation mechanisms and the strength of untreated wood components. While extensive work has been performed characterizing wood decay, no study has yet addressed the effects of Meruliporia incrassata on untreated Southern Yellow Pine. This seeks to address this knowledge gap by evaluating the effects of the common brown rot fungus on an ubiquitous building material in the southeast United States – Southern Yellow Pine. Properties of Southern Yellow Pine were evaluated at seven decay stages over the course of 12 weeks of exposure to M. incrassata. Changes in physical properties – mass, density, and moisture content – were measured at each stage. Changes in stiffness were characterized via ultrasonic pulse velocity testing, and thermogravimetric analysis was utilized to assess compositional changes. The study found rapid and significant losses in stiffness at decay stages as early as four-weeks. Hemicellulose and cellulose degradation occurred steadily throughout the decay period. These results can be utilized to develop a stronger understanding of the mechanical behavior of timber-framed structures in the United States degraded by brown rot.