Layering Research Articles

Early frost detection in wheat using machine learning from vertical temperature distributions

Frost damage significantly reduces global wheat production. Temperature development in wheat crops is a complex and dynamic process. During frost events, a vertical temperature gradient develops from soil to canopy due to the heat loss from the soil and canopy boundary. Understanding these temperature gradients is essential for improving frost management strategies in wheat crops. We hypothesise that the relationship between the temperatures of the canopy, plant and ground can be an early indicator of frost. We collected infrared thermal (IRT) images from field-grown wheat crops and extracted the temperatures from the canopy, plant and ground layers. We analysed these temperatures and applied four machine learning (ML) models to detect coldness scales leading to frost nights with different degrees of severity. We implemented a gated recurrent unit, convolutional neural network, random forest and support vector machines to evaluate the classification. Our study shows that in these three layers, temperatures have a relationship that can be used to determine frost early. The patterns of these three temperatures on a frost night differ from a cold no-frost winter night. On a no-frost night we observed that the canopy is the coldest, plant is warm, and the soil is warmest, and these three temperatures did not converge. On the other hand, on a frost night, before the frost event, the canopy and plant temperatures converged as the cold air penetrated through the canopy. These patterns in temperature distribution were translated into an ML problem to detect frost early. We classified coldness scales based on the temperatures conducive to frost formation of a certain severity degree. Our results show that the ML models can determine the coldness scales automatically with 93%–98% accuracy across the four models. The study presents a strong foundation for the development of early frost detection systems.

Drag reduction performance of discrete superhydrophobic surfaces in von Kármán swirling flow

Enhancing the energy efficiency and mitigating environmental pollution in maritime transportation relies significantly on minimizing frictional drag of ships. In this study, we employ wettability dividing lines and convex stripes to discretize the continuous air layer on superhydrophobic surfaces, offering a mechanism to enhance their drag reduction efficacy. Initially, we theoretically analyze the stabilization of the air layer on superhydrophobic surfaces through wettability dividing lines and convex stripes. Subsequently, torque measurements are conducted to characterize drag reduction performance in von–Kármán swirling flow. The drag reduction parameters that performed optimally were determined experimentally by parametric analysis, with a 20–mm spacing identified for the hydrophilic ring on the wettability difference surface, and a 20–mm spacing with a 2–mm height for the convex stripe on the superhydrophobic surface. Under these specified parameter values, the maximum Reynolds number for effective drag reduction (Rec) increases from 1.62 × 105 to 3.24 × 105, and the drag reduction rate at Rec = 3.24 × 105 reaches 32.29% and 26.61%, respectively. Moreover, coupling wettability dividing lines with superhydrophobic convex stripes further enhances Rec to 4.05 × 105, and the drag reduction rate stabilizes at around 30% within the maximum Reynolds number.

Air mass transport to the tropical western Pacific troposphere inferred from ozone and relative humidity balloon observations above Palau

Abstract. The transport history of tropospheric air masses above the tropical western Pacific (TWP) is reflected by the local ozone and relative humidity (RH) characteristics. In boreal winter, the TWP is the main global entry point for air masses into the stratosphere and therefore a key region of atmospheric chemistry and dynamics. Our study aims to identify air masses with different pathways to the TWP using ozone and radio soundings from Palau from 2016–2019. Supported by backward trajectory calculations, we found five different types of air masses. We further defined locally controlled ozone and RH background profiles based on monthly statistics and analyzed corresponding anomalies in the 5–10 km altitude range. Our results show a bimodality in RH anomalies. Humid and ozone-poor background air masses are of local or Pacific convective origin and occur year-round, but they dominate from August until October. Anomalously dry and ozone-rich air masses indicate a non-local origin in tropical Asia and are transported to the TWP via an anticyclonic route, mostly from February to April. The geographic location of origin suggests anthropogenic pollution or biomass burning as a cause for ozone production. We propose large-scale descent within the tropical troposphere and radiative cooling in connection with the Hadley circulation as being responsible for the dehydration during transport. The trajectory analysis revealed no indication of a stratospheric influence. Our study thus presents a valuable contribution to the discussion about anomalous layers of dry ozone-rich air observed in ozone-poor background profiles in the TWP.

A computational model of an air-layer radiant cooling panel for optimizing and design

Radiant cooling systems have become a research hotspot in recent years. The air-layer radiant cooling panel always had good performance, but there is relatively little research on it. This paper aims to optimize an air-layer radiant cooling panel by establishing a computational model and analyzing its accuracy through experiments. Through the computational model, the effects of surface emissivity, the thickness of the air layer and high thermal resistance material, pipe spacing on the heat transfer performance of the air-layer radiating cooling panel, and the corresponding optimizations have been studied in this paper. Based on the results, it is recommended that a pipe spacing of between 0.1 m and 0.25 m can achieve higher cooling capacity and lower initial costs. The thinner the thickness of the air layer and decorative layer, the better the heat transfer performance. High emissivity materials need to be used on the surface of the air-layer radiant cooling panel to enhance radiant heat transfer. In the process of analyzing the spacing between pipes, a method for calculating the large temperature difference of the fluid has been added, which can help us estimate the cooling capacity in practical engineering, balance initial costs and cooling capacity, and better meet cooling needs.

Experimental and numerical investigations of multi-layered ship engine room bulkhead insulation thermal performance under fire conditions

Abstract The thermal insulation layer of the ship’s engine room bulkhead is typically constructed from multiple layers of mineral wool. This layer is designed to keep the temperature on the surface of the bulkhead below 140°C in case of a fire. However, measuring the inner and external temperatures of each wall panel bulkhead type during a fire can be difficult. To address this issue, this study was conducted to evaluate the multilayer heat transfer capability of the bulkhead insulation in the event of an engine room fire. The study used heat transfer theory, experimental models, and numerical analysis to assess nine bulkhead insulation specimens. These specimens were fabricated from three original specimens and included a 10–30 mm air layer (W-75, W-50, and W-25). The results showed that all improved specimens had better thermal insulation than the originals. Among them, the improved specimens derived from the W-25 specimen exhibited the most significant temperature reduction compared to those derived from the W-75 and W-50 specimens. The results demonstrated a slight difference between the three methodologies, indicating a high level of reliability in the research findings.

Investigation of Displacements in Tunnel-Constructed Liquefiable Soils with Numerical Analysis

The rise in industrialization and population has led to an increase in the economic significance of existing urban areas, and thus the utilization of underground space has become quite remarkable It is an undeniable fact that in seismically active regions, the underground areas are also exposed to the risk of earthquakes. The devastating 1995 Kobe-Japan, 1999 Chi-Chi-Taiwan and 1999 Kocaeli-Turkey earthquakes are known to have caused major damage to existing underground structures. In this study, numerical models based on finite differences in FLAC 2D were established to evaluate the displacements of the ground around the tunnels located in liquefiable soils. In order to represent the liquefaction condition in the models, soils in the Adapazarı region, which have alluvial characteristics, were used. Soil deformations were examined in models with varying tunnel depths and diameters, for both liquefiable and non-liquefiable soils within the same layers. As a result of this study, it is stated that more stability losses are observed in analyzes where liquefaction can be defined - that is, changes in pore water pressures can be modeled - compared to analyzes without liquefaction. The layout of the ground layers is important for the positioning of the tunnel. The placement of the tunnel towards the solid layers caused the deformations to decrease.

Improving the Quality of Laser Drilling by Assisted Process Methods of Static Solution and Mist Blowing.

The use of static solution-assisted laser drilling can effectively improve hole roundness, decrease taper angle, and reduce recast layer thickness and hole wall slag adhesion. However, the enormous energy of the laser will evaporate the solution to form a suspension droplet and reduce the quality and efficiency of laser drilling. To deal with this defect, the mist-blowing method was used to reduce the influence of droplets on the taper angle and recast layer. In this work, the effect of wind speed on drilling quality was examined, and laser drilling in air, water, and NaCl solution was carried out to analyse the effect of solution composition on hole wall morphology. The results showed that a speed fan with a proper wind speed that disperses the droplets formed in the processing area can significantly reduce the refraction and scattering of the laser, and the taper angle and roundness of the drilling hole were also reduced by 15.6% and improved by 2.4%, respectively, under the wind speed of 2 m/s. The hole wall morphology showed a thicker recast layer and cracking in air, while it was thinner in water and there was little or no layer in the NaCl solution in the same current. When drilling in NaCl, the taper angle and roundness of the drilling hole were reduced by 4.13% and improved by 2.11%, respectively, compared to water. Due to the mechanical effect of the laser in the NaCl solution, the impact force on the material was much greater than that in water. The solution cavitation effect, generated by the absorption of laser energy, caused an explosive impact on the molten material adhered to the surface of the hole wall. Above all, drilling in the NaCl solution with a current of 200 A and a wind speed of 2 m/s was the optimal condition for obtaining the best processing quality.

Design of Microstrip Antenna Arrays with Rotated Elements Using Wilkinson Power Dividers for 5 G Customer Premise Equipment Applications

Microstrip antenna arrays are proposed in this paper for the customer premise equipment (CPE) applications in the frequency range 1 (FR1) of the 5th generation (5 G) mobile networks. The proposed antenna arrays consist of three FR4 substrates. Antenna elements and feeding networks are optimized separately through parameter studies and then combined to form the proposed antenna arrays. Bandwidth-enhancing parasitic elements on the top substrate are broadside coupled to the microstrip antennas in the middle substrate, which are probe-fed by the microstrip feeding network using Wilkinson power dividers realized in the bottom substrate through the ground plane and the stud supporting air layer between the lower two substrates. Two antenna arrays, with four and eight antenna elements, are proposed for different gain specifications, 10 dBi and 12 dBi, respectively. Bandwidths of 10-dB return loss for both arrays fully covered the 5 G n78 frequency band (3.3–3.8 GHz). 20 dB isolation between antenna elements can also be achieved using the proposed layouts with rotated elements. The dimensions, radiation gain, and efficiency of the proposed antenna units, four-element array, and eight-element array are 65 × 65 × 11.4, 115 × 115 × 11.4, and 115 × 215 × 11.4 mm3, 6.2, 10.5, and 13 dBi, 74%, 56%, and 50%, respectively. The proposed antenna arrays exhibit the advantages of simple, low-cost, low-profile, and high-gain characteristics, which is potentially applicable to 5 G CPE outdoor unit (ODU)-related devices.

Optimizing SOI-MESFET transistor performance at high frequencies by air-oxide layers in the channel and a nickel layer in the box

In this paper, we introduce a new transistor structure that has improved alternating current and direct current parameters compared to the basic structure. The cutoff frequency of the proposed structure is 33 GHz, while the cutoff frequency of the basic structure is 25.5 GHz. One important improvement is that the gate-drain parasitic capacitors in the channel area are nearly zero, thanks to the presence of an air layer between the gate and source electrodes and a nickle layer in the burried oxide. In addition to the alternating current parameters, the direct current parameters have also been strengthened. The maximum output power density for the new structure is 1.08 W/mm, compared to 0.455 W/mm for the normal structure. Furthermore, the breakdown voltage in the new structure has increased to 30 V, while the basic structure has a breakdown voltage of 16 V. These improvements are attributed to the transfer of the gate to the source and the increased distance from the drain region, as well as the presence of two layers of oxide and air on both sides of the gate. Consequently, the new structure can effectively operate at high voltages and powers.

A Stretchable Thermoelectric Device based on Direct Ink Writing of Liquid Metal and Multi‐Layer Lamination

AbstractWearable thermoelectric devices are widely used due to their ability to generate heat and cool rapidly without the need for bulky external equipment. Researchers have explored methods to enhance flexibility and stretchability by incorporating liquid metal as an electrode. However, the challenge lies in the low thermal conductivity of the polymer, which hampers heating and cooling performance. Traditional methods, like molding and spraying, increase the thickness of both liquid metal and polymer channels, but this added thickness does not significantly improve the device's stretchability.[1, 2] To overcome these issues, this paper proposes a stretchable thermoelectric device (STED), which offers improved heating and cooling capabilities, as well as enhanced stretchability. To enhance the thermal conductivity of the polymer, Ag powder with varying particle sizes is mixed with the material. Additionally, the liquid metal is deposited using the direct ink writing (DIW) method, reducing the whole thickness of STED. The air layer is created by printing molten isomalt, which is subsequently removed using water. The proposed STED exhibits high stretchability, reaching up to 150 %, enabling flexible twisting in various directions. The double‐layer structure resulted in a maximum temperature decrease of 14 °C at room temperature.

ВЛИЯНИЕ ОТКАЗА РАБОТЫ ОБЛИЦОВОЧНЫХ ПАНЕЛЕЙ НА ТЕПЛОТЕХНИЧЕСКИЕ СВОЙСТВА НАВЕСНЫХ ВЕНТИЛИРУЕМЫХ ФАСАДНЫХ КОНСТРУКЦИЙ

Abstract. One of the most common solutions for external enclosing wall structures are hinged ventilated façade structures, which, thanks to the use of air layers, provide increased energy efficiency. However, such systems have a number of drawbacks, including the formation of cold bridges in the places of attachment of facade panels, which can lead to significant problems in the operation of the system. In addition, it is known that individual facade panels can fall and refuse to work, which leads to a violation of the closure of the air layer and negatively affects the thermal properties of the structure. Therefore, it is necessary to take into account both the shortcomings of the facade structure itself and the problems associated with its operation in order to correctly assess the impact of the failure of the facade panels on the thermal properties of the structure as a whole. This problem is one of the most important for systems of hinged ventilated facades, as it can lead to a complete loss of thermal engineering properties of the structure. This study considers a theoretical solution to the problem of calculating the heat transfer resistance of air layers in hinged ventilated facade structures and organizing this solution into a consistent design methodology for further investigation of the effect of the fall of facing panels on thermal engineering properties of hinged ventilated facades. The main question of the study, consisting in assessing the impact of the failure of the cladding panels on the thermal properties of hinged ventilated facade structures, is considered in accordance with the provisions of the developed methodology and its subsequent mathematical analysis. The need for such a study is justified by the need to determinethe most effective ways to eliminate the shortcomings of hinged ventilated facade structures and increase their thermal properties.
 Materials and methods: analysis of scientific and technical literature, mathematical analysis of the dependence of the resistance to heat transfer of air layers on the geometric parameters of the structure.
 Subject of research: air layers in hinged ventilated façade structures.
 Results: mathematical dependences are obtained that allow us to estimate the change in the moisture content of the thermal insulation material of hinged facade systems, the air velocity in the air layer and the air temperature in the air layer because of facing panel’s failure. 
 Conclusions: failure of facing panels of hinged facade systems leads to a change in the humidity of the thermal insulation and the parameters of the air layer, which can lead to exceeding regulatory requirements.

Plasmonic wave assessment via optomechatronics system for biosensor application

Transduction biosensor (mass-based, optical and electrochemical) involves analysis, recognition and amplification in the acquired sample. In this work, the plasmonic-based biosensor was employed without using tags. It is crucial to determine angles of Brewster (Ɵb) and critical (Ɵc) for generating plasmonic resonance (Ɵr). The objective is to verify a cost-effective plasmonic biosensor through Fresnel simulation and experimentation of a developed optomechatronics system. The borosilicate glass, Au and Air layers were simulated with the Winspall 3.02 simulator. The optomechatronics system consists of: 1-optics (650 nm laser, slit, polarizer, photodiode), 2-mechanical (bipolar stepper motors, gears, stages) and 3-electronics (PIC18F4550, liquid crystal display (LCD) and drivers). Later, the software performs angular interrogation by reading the reflected beam from a rotating prism at 0.1125. Experimentation to simulation accuracy indicates that percentage differences for Ɵr and Ɵc are 1% and 0.2%, respectively. In conclusion, excellence verification was successfully achieved between experimentation and simulation. It proved that the low-cost optomechatronics system is capable and reliable to be deployed for the biosensor application.

Bounce and contact mode regimes for drop impact on smooth surfaces: The influence of gas kinetics and electrostatics

When liquid drops impact on solid surfaces, an air layer forms in between the drop and the surface, acting as a cushion to mitigate the impact. In this work, we focus on delineating the bounce and contact mode regimes of impacting drops on smooth surfaces, specifically discerning whether drops rebound from the air layer or make contact with the solid surfaces, and pinpointing the precise contact modes between the drop and solid surfaces by resolving the gas film evolution and rupture. Our simulation model incorporates gas kinetics and electrostatics effects, both of which have been validated by experiments documented in the literature or theoretical models regarding thin film instabilities. We undertake a comprehensive review and categorization of the contact modes and elucidate how they change under different conditions of impact velocities, ambient pressures, and electric field intensities. We also provide some perspectives on the regime map for the lubricated surfaces, which contains an unresolved issue that the critical Weber number for bouncing-wetting transition is significantly reduced compared to the solid smooth surfaces like mica. These insights have noteworthy practical implications offering guidance for a wide range of scenarios, from normal-pressure environments to low-pressure conditions at high altitudes, encompassing high electric field conditions such as nanogenerators as well as low electric field conditions resembling glass surfaces with static electricity.

Bayesian estimation of dissipation and sound speed in tube measurements using a transfer-function model.

This study discusses acoustic dissipation, which contributes to inaccuracies in impedance tube measurements. To improve the accuracy of these measurements, this paper introduces a transfer function model that integrates diverse dissipation prediction models. Bayesian inference is used to estimate the important parameters included in these models, describing dissipation originating from various mechanisms, sound speed, and microphone positions. By using experimental measurements and considering a hypothetical air layer in front of a rigid termination as the material under test, Bayesian parameter estimation allows a substantial enhancement in characterization accuracy by incorporating the dissipation and sound speed estimates. This approach effectively minimizes residual absorption coefficients attributed to both boundary-layer effects and air medium relaxation. The incorporation of dissipation models leads to a substantial reduction (to 1%) in residual absorption coefficients. Moreover, the use of accurately estimated parameters further enhances the accuracy of actual tube measurements of materials using the two-microphone transfer function method.

Dynamical study of three African Easterly Waves in September 2021

AbstractThree convectively active African easterly waves (AEWs) that propagated south of the African easterly jet were observed over the northeast Atlantic Ocean in September 2021. Their evolution is studied using a suite of theoretical frameworks, as well as the European Centre for Medium‐range Weather Forecast reanalyses and satellite‐derived brightness temperature observations. The environment of these AEWs was sampled during the Cloud–Atmospheric Dynamics–Dust Interactions in West Africa campaign near Cape Verde with the goal to assess their potential for developing into tropical cyclones. We highlight the processes that inhibited the development of the first AEW (which evolved into tropical disturbance Pierre‐Henri) and that played a role in the development of the later two into tropical storms Rose and Peter on September 19, 2021. The three AEWs developed a so‐called “marsupial protective” pouch. For Peter and Rose, the pouch was associated with a vertically aligned vortex at low levels and efficiently protected the convective systems inside from dry and dusty air intrusion. The development of this low‐level vortex is associated with an interaction with the monsoon trough for Rose and with a vorticity center associated with a wave propagating north of the African easterly jet (AEJ) in the case of Peter. The presence of a dust flux toward the convective core near the surface is highlighted for Rose and Peter in spite of the presence of the protective marsupial pouch. On the other hand, Pierre‐Henri interacted positively with both the monsoon trough and an AEW north of the AEJ but failed to develop into a tropical cyclone. The wave north of the AEJ brought Saharan air layer air masses inside the pouch that led to a drying of the circulation that may explain the decrease in convective activity.

Identification Of Dry Eye Syndrome Risk Factors In Workers Who Use Visual Display Terminals (VDT)

Dry eye syndrome is a multifactorial disease of the eye air and eye surface which causes symptoms of discomfort, visual disturbances, and instability of the eye air layer which has the potential to damage the eye surface. This condition has an impact on productivity, activities in the work environment, apart from that it also has an impact on lower employment opportunities, decreased working hours and increases a person's inability to work. Using visual display terminals for 5-7 hours/day can significantly increase the incidence of dry eye syndrome. Therefore, paying attention to the risk factors of visual display terminal workers is very important in preventing the occurrence of dry eye syndrome. The research method uses literature studies from several national and international journals obtained from 18 reference sources through searches on PubMed and Google Scholar published in the last 5 years. There were 18 articles with full text that met the inclusion criteria and contained several risk factors associated with the incidence of dry eye syndrome. Risk factors for dry eye syndrome in workers who use visual display terminals include age, gender, screen exposure time, psychological stress, work environment, use of contact lenses, use of drugs and history of surgery, refractive disorders, and length of work. Identification of risk factors for dry eye syndrome in workers who use visual display terminals can reduce the incidence and morbidity associated with this disease. So it can improve the quality of life of workers

Filtenna Designed with Defected Ground Structure (DGS) for Ultra-wideband Applications

In microwave imaging applications, filter and antenna are the key components as front-end devices and function independently. Antenna radiates and receives signals to or from nearby scattered objects while filter is used to suppress unwanted signals noise before and after the required bandwidth. Current antennas suffer from high loss, bandwidth limitation and impedance mismatch and deteriorate their performance near the band-edges if connected as a stand-alone device. Due to the current trend towards simplicity and size reduction, researchers are focusing on integrating the filter and antenna into a single module called integrated filter-antenna (IFA) or filtering antenna (filtenna). These would improve the noise performance of the system and pre-filtering requirements such as complexity algorithm in inverse scattering techniques This paper introduces a novel contribution in the field of UWB antenna design by incorporating Defected Ground Structure (DGS) on both the antenna and filter. Thus, the main aim of this research is to conduct detail parametric studies of the proposed integrated filter-antenna with defected ground structure (DGS) to enhance the performance of imaging system. The proposed IFA will be analysed on Rogers RO4003C dielectric substrate by using EM tool, Computer Simulation Technology (CST) and measured using R&S Vector Network Analyzer (VNA). A compact ultra-wideband (UWB) filter and UWB elliptical antenna are designed and examined in detail before combining the devices. Different types of DGS are designed and act as the ground layer of the proposed filtering antenna. The bandwidth of each design is then compared with and without the existence of DGS. The results show that the proposed IFA with DGS implementation achieve the targeted objective, with compact size, enhanced bandwidth and better performance compared to the conventional design of filter and antenna. By integrating filter and antenna into one subsystem, it can help to reduce the loss and enhancing the bandwidth of the system thus letting the antenna to operate at more different frequencies that fall within the range. Both simulated and measured results prove that by integrating filter and antenna into one module, a low loss and larger bandwidth can be accomplished. High performance compact IFA can act as microwave transceiver to improve the overall performance of the microwave imaging system, MIS.

Air entrainment by a hydrofoil in a high-speed water flow for design of bubbly drag reduction ships

We have investigated the flow behavior around a hydrofoil bubble generator in a high-speed channel flow up to 10 m/s for the first time to understand the air entrainment characteristics of this hydrofoil device caused purely by the inertia effect of water flow. This study is motivated by our previous success in achieving ship drag reduction for full-scale vessels (Kumagai et al., 2015). Depending on the water flow velocity U and the angle of attack of the hydrofoil α, three different major patterns were identified: continuous generation of dispersed bubbles, intermittent formation of an air cavity, and steady formation of a super air cavity that stretched behind the hydrofoil. The transition from the dispersed bubble state to the air cavity formation regime is explained theoretically using the equation of bubble motion coupled with a potential flow analysis. The air volume flow rate increased linearly with U, and its slope was steeper in the dispersed bubble state than in the air cavity formation regime. The highest air flow rate was realized at U = 9 m/s, which corresponds to the nominal air layer thickness at ta = 4.1 mm, and reaches the feasible range for realization of bubbly drag reduction for a long ship hull.

Compact and high gain cup-shaped 4-Port MIMO antenna using low profile material for the sub-6 GHz, IoT and military applications

The article introduces a novel design of a miniaturised and high-gain 4-Port MIMO antenna ingeniously crafted as a cup. The evolution of the radiating structure, achieved through meticulous iterations involving alterations to the patch element’s shape and feedline modifications, underscores the commitment to optimal performance. Leveraging parametric analysis, which includes strategic adjustments to the ground layer’s length, incorporation of vertical and horizontal slots, and the addition of a parasitic patch in the top layer, our proposed framework spans the spectrum from 1 GHz to 14 GHz. The antenna exhibits a tripartite frequency response at 4.6 GHz, 8.7 GHz, and 13 GHz, showcasing a peak bandwidth of 5.5 GHz and a minimum return loss of −24.22 dB. Remarkably, the design achieves a peak gain of 8.32 dB, coupled with stellar performance in diverse parameters such as ECC, MEG, TARC, CCL, and DG. Constructed with low-profile FR4 material, the antenna thoroughly compares simulated and measured results, affirming its robust performance. This innovative architecture, poised for Sub6GHz, IoT, and military applications, not only pushes the boundaries of antenna design but also stands out as a significant advancement in the field.

Fracture toughness of aged oil paints

The fracture toughness in opening mode GIc for selected oil paints from Mecklenburg's Paint Reference Collection after approximately 30 years of natural ageing was determined using the procedure adopted from the ASTM D5528–13 standard in which double cantilever beam specimens are split in tensile tests. The careful reglueing procedure allowed multiple fracturing tests to be carried out that not only improved statistics of the measurements but also provided insight into the variation of the fracture toughness across the paint film observed for some paints. The latter was due to pigment sedimentation or chemical change of the oil binder as a result of the easier access of oxygen from the side open to the air. For the lead white paint, used over centuries both in paint films and oil grounds, the GIc values more than doubled from 18 to 39 J/m2 for three consecutive cracks formed at an increasing distance from one side of the paint film. The study demonstrated that fracture toughness corresponding to the first crack formation in aged oil paints ranged between 10 and 40 J/m2, relatively low values compared to the animal glue-based ground in paintings. In consequence, oil paints are more vulnerable to crack initiation and growth induced by tensile stress than the ground layer. The measurements filled the gap in the knowledge required for the analysis of fracturing or delamination processes in paintings.