Characteristic Diameter Research Articles

Influence of Environment Conditions on Ultrasonic and Electrostatic Precipitation of Aerosols of Wood Flour

The risk of human exposure to finely-dispersed aerosol particles being airborne indoors is determined by the size and the number concentration of particles, the intensity of an aerosol emission source, the air filtration and ventilation efficiency, etc. The emphasis in this article is on behaviour patterns of aerosol particles when exposed to ultrasonic and electrostatic fields in different conditions of air temperature and relative humidity. Wood flour having sizes of interest (characteristic particle diameter about 10 μm) is chosen as a model aerosol. The article considers a physical and mathematical model presenting the evolution of aerosol particles in external fields, taking into account the moisture content and the temperature of a dispersive medium. The efficiency of ultrasonic and electrostatic precipitation in different relative humidity and temperature conditions in an enclosed space was studied using optical measurement methods of particle size and concentration.

Morphology and biochemistry of achacha (Garcinia humilis (Clusiaceae) (Vahl) C.D. Adam) fruits harvested at three consumption ripeness stages

Objective: To identify the morphological and biochemical variations of achacha (Garcinia humilis (Clusiaceae) (Vahl) C.D. Adam) in three ripeness stages of consumption. Design/Methodology/Approach: The morphological and biochemical variables of fruits in three ripeness stages were evaluated to identify the preferred stage for consumption. We collected 15 fruits from 10 productive-stage trees (n=150) for each ripeness stage for their subsequent evaluation in the laboratory. The morphological and biochemical variables were evaluated in each one. Each fruit was considered an experimental unit. The morphological and biochemical variables were evaluated for each unit. Results: Delaying the harvest for a few days increases the weight, length, diameter, and pulp:seed ratio of the fruits and decreases the firmness of the epicarp and the acidity. The °Brix increases and the fruits lose a considerable weight during storage. The pulp of the ripest fruits had light and unsaturated colors. Study Limitations/Implications: Changes in the conditions of the production systems and the variation in the availability of rainwater throughout the year and from one year to another can cause variation in fruit quality. Findings/Conclusions: The ripest fruits had outstanding biochemical parameters for its consumption and better morphological characteristics (length, total weight, diameter, and pulp:seed ratio). With adequate training, the results enable the color of the epicarp and the pulp variables to be used as a harvest index.

Pore structure characteristics and permeability analysis of natural anhydrite with various water /anhydrite ratios based on mercury intrusion porosimetry

The characteristics of the gypsum pore structure are closely related to its macroscopic mechanical properties and permeability. Recent research on anhydrite-based cementitious materials is mainly focused on modification and enhancement and their effect on pore structure characteristics, while the relationship between pore structure and permeability remains unclear. Here, we characterized the pore structure and permeability of natural anhydrite-based cementitious material under various water-anhydrite (W/A) ratios based on the mercury intrusion porosimetry, intending to investigate the relationship between these two parameters. This paper investigated the effect of the W/A ratio on the characteristic pore diameter of natural anhydrite-based cementitious materials. The hydration products optimize the pore structure through the filling effect to form a dense spatial structure, thereby improving the mechanical properties and permeability of the hardened body, where porosity is the main factor affecting the mechanical properties. The multifractal characteristics of natural anhydrite-based cementitious materials and the pore size dependence of permeability were clarified, and the thermal fractal dimension of its small pore range (4–1 600 nm) satisfied the k = aDb relationship with the permeability coefficient based on the Katz-Thompson model, providing a novel thought for the calculation and research of the permeability of anhydrite-based cementitious materials.

Influence of the assisted kerf depth on cracks pattern and cutting performance of TBM cutter

Kerfing on the working face of tunnel boring machine (TBM) can reduce the integrity of intact rock mass, it's one of feasible methods to improve the TBM performance. When the TBM cutter cut along the midline of two kerfs, the chipping mechanism changed to the interaction between the cutter and adjacent kerfs, the lateral cracks generated from the cutter tip could propagate to the bottom of adjacent kerfs. To study the effects of kerf depth on the cracks pattern and the cutting performance of the TBM cutter, a series of full-scale linear rock cutting tests were conducted. In addition, conventional cutting tests without kerfs were also performed to make a comparison. The cutter force and rock muck were collected, and the rock samples were sectioned after the tests. The cracks patterns beneath the cutter tip were observed by fluorescent dye. The results show that the dip angle of the lateral cracks increase with the increasing kerf depth, the vertical cracks become shorter and less. Besides, the area of the crushed zone decreases. The required normal force and rolling force are much reduced even for the large cutter penetration compared with the conventional cutting. The cutter forces decrease, while the characteristic grain diameter and coarseness index of the rock muck increase with the increasing kerf depth. The specific energy of kerf-assisted cutting is lower than that of the conventional cutting, and it declines as the kerf depth increases. A critical kerf spacing to depth ratio is found to efficiently reduce the specific energy. The results are useful for the rational parameter design of the kerfing system installed on the new generation TBM. The kerf spacing could be enlarged to save energy if the kerfs are deeper than 12 mm. However, it's still a challenging task to create deep kerfs on site.

The Effect of Environmental Disasters on Endocrine Status, Hematology Parameters, Body Composition, and Physical Performance in Young Soccer Players: A Case Study of the Aral Sea Region.

The Aral Sea region (Uzbekistan) is infamous because of the ecological disaster characterized by the disappearance of the Aral Sea due to excessive uncontrolled water intake for agriculture needs. A new desert occurrence, soil and climate aridization led to pesticide and toxic metals environment pollution. The impact of environmental conditions in some areas of Uzbekistan on the health of soccer players is not as noticeable as, for example, the effectiveness of training, so it is not widely discussed in scientific papers. The aim of the present study was to study the features of endocrine status, hematology parameters (e.g., red blood cells (RBC) and hemoglobin (Hb)), and their influence on body composition and physical fitness performance in local young soccer players of the Aral Sea region as the territory of ecological disaster. The study involved 60 male soccer players aged from 18 to 22 years. Participants were divided into two groups: the experimental group (EG), which consisted of 30 soccer players living on the territory of the Aral ecological disaster region, and the control group (CG), which included 30 soccer players, natives of the ecologically favorable region of Uzbekistan. All volunteers had anthropometric measurements, concentrations of insulin-like growth factor-1 (IGF-1), total testosterone (TT), estradiol (E2), cortisol (C), RBC, and Hb count. Moreover, Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1) and professional skills tests such as dribbling shuttle test (DSt) and goal accuracy test (GAt) were assessed. When comparing the CG group to the EG group, it was observed that the EG group exhibited statistically significantly reduced levels of TT and E2 (p < 0.05). No significant statistical difference was observed between the two groups in terms of IGF-1 and C (p > 0.05). Regarding hematological parameters, Hb, Ht, and mean corpuscular volume (MCV) were found to be significantly lower in the EG compared with the CG (p < 0.05). Moreover, the distance covered in the YYIR1 test was found to be significantly lower in soccer players within the EG compared with the CG (p < 0.05). Additionally, it was determined that there was no significant difference between the groups in terms of DSt and GAt values (p > 0.05). Lastly, significant differences were observed between the EG and CG in terms of anthropometric characteristics (diameters, skinfold, and somatotype profile) (p < 0.05). The present study showed that the changes in evaluated characteristics might result from the complex influence of endocrine-disrupting chemicals, the content of which is high in the environment of the Aral Sea region. The results obtained may help monitor the health of athletes living in an environmentally unfriendly environment.

Hydrosedimentological characterization of a reach in the Forqueta River catchment, south Brazil

We conducted an analysis on the hydrosedimentological characteristics of a section of the Forqueta River, located in southern Brazil. This river is part of a catchment area with steep slopes and fast-flowing water, and it is characterized by a gravel bed. A total of twenty-five sections were surveyed, representing three distinct morphologies (cascade, pool, and plane-bed). We estimated hydraulic variables and determined the characteristic diameters of sediments. The channel morphology in each section was observed throughout the course of a year, capturing seasonal variations. The findings of this study indicated that the cascade areas exhibited the highest values of sediment grain size, while the pool regions displayed greater variability in terms of channel morphology. We observed that higher values of channel slope had a significant influence on relative submergence, Darcy-Weisbach friction factor, and Manning's roughness coefficient. The pool morphology demonstrated higher granulometry values and a wider range of diameter values compared to the cascade morphology. No significant difference in the seasonality of the measurements was observed among the three different channel morphologies.

Assessment of the Significance of Identified Attributes Affecting the Rebar-Fixing Productivity Using Multiple Regression

Reinforced concrete structures are an inherent part of the construction sector. Every in situ reinforced concrete structure cardinally involves rebar-fixing works, which entails activities like transporting, marking, laying, and tying the rebar for the components under construction. Rebar-fixing absorbs a significant number of man-hours during the operation. Therefore, productivity of rebar fixers is a critical concern in construction. Several attributes influence rebar-fixing productivity. Former studies have investigated the impact of the attributes separately and predominantly using qualitative data. A few studies have assessed rebar productivity quantitatively but ignored the effects of some crucial parameters, such as congestion, crew composition, and construction delays. Moreover, studies are limited to account for all time proportions like productive, semiproductive, and nonproductive while assessing rebar productivity. Therefore, this study addresses the aforementioned research gaps by assessing the impact of diverse attributes using direct measures of rebar-fixing productivity and its attributes. Initially, hypotheses were developed to determine the influence of eight attributes identified in this study on rebar-fixing productivity. Next, the data were recorded from one large construction project in Gujarat, India. The work sampling approach was adopted for the productivity assessment of rebar fixers at the project site to evaluate each time proportion. Furthermore, the stepwise regression analysis was performed on the data set to examine the hypotheses. Results indicate that attributes such as quantity of reinforcement, characteristic rebar diameter, and congestion have a significant positive impact on rebar-fixing productivity, whereas work duration has a significant negative impact on it. The outcomes of this research can aid the site management, structural engineers, and construction planners in decision-making to enhance the productivity of rebar fixers, thereby adhering to the budget and schedule constraints of the project.

Liquid‐Liquid Emulsion Produced by 3D‐Printed Vortex‐Based Hydrodynamic Cavitation Device

Abstract3D‐printed vortex‐based devices have shown excellent performance in realizing hydrodynamic cavitation (HC) and have opened up new ways of effectively producing oil‐in‐water emulsions via cavitation. In this work, the performance of machined and 3D‐printed vortex‐based HC devices for producing liquid‐liquid emulsions was compared in terms of droplet breakage efficiency and energy consumption per kilogram of emulsion. The Euler numbers of 3D‐printed and VMC‐machined HC devices were 42 and 48, respectively. The differences in droplet size distribution and other characteristic diameters were insignificant after 50 passes. The present work confirms the potential of harnessing 3D printing technology for fabricating HC devices and can facilitate development of new device designs to improve overall emulsification performance.

A light scatter based model relating erythrocyte vesiculation to lifetime in circulation.

Methods for measuring erythrocyte age distribution are not available as a simple analytical tool. Most of them utilize the fluorescence or radioactive isotopes labeling to construct the age distribution and support physicians with aging indices of donor's erythrocytes. The age distribution of erythrocyte may be a useful snapshot of patient state over 120-days period of life. Previously, we introduced the enhanced assay of erythrocytes with measurement of 48 indices in four categories: concentration/content, morphology, aging and function (10.1002/cyto.a.24554). The aging category was formed by the indices based on the evaluation of the derived age of individual cells. The derived age does not exactly mean the real age of erythrocytes and its evaluation utilizes changes of cellular morphology during a lifespan. In this study, we are introducing the improved methodological approach that allows us to retrieve the derived age of individual erythrocytes, to construct the aging distribution, and to reform the aging category consisting of eight indices. The approach is based on the analysis of the erythrocyte vesiculation. The erythrocyte morphology is analyzed by scanning flow cytometry that measures the primary characteristics (diameter, thickness, and waist) of individual cells. The surface area (S) and sphericity index (SI) are calculated from the primary characteristics and the scattering diagram SI versus S is used in the evaluation of the derived age of each erythrocyte in a sample. We developed the algorithm to evaluate the derived age that provides eight indices in the aging category based on a model using light scatter features. The novel erythrocyte indices were measured for simulated cells and blood samples of 50 donors. We determined the first-ever reference intervals for these indices.

A Controlled-Release Nanofertilizer Improves Tomato Growth and Minimizes Nitrogen Consumption.

Minimizing the consumption of agrochemicals, particularly nitrogen, is the ultimate goal for achieving sustainable agricultural production with low cost and high economic and environmental returns. The use of biopolymers instead of petroleum-based synthetic polymers for CRFs can significantly improve the sustainability of crop production since biopolymers are biodegradable and not harmful to soil quality. Lignin is one of the most abundant biopolymers that naturally exist.In this study, controlled-release fertilizers were developed using a biobased nanocomposite of lignin and bentonite clay mineral as a coating material for urea to increase nitrogen use efficiency. Five types of controlled-release urea (CRU) were prepared using two ratios of modified bentonite as well as techniques. The efficiency of the five controlled-release nano-urea (CRU) fertilizers in improving the growth of tomato plants was studied under field conditions. The CRU was applied to the tomato plants at three N levels representing 100, 50, and 25% of the recommended dose of conventional urea. The results showed that all CRU treatments at the three N levels significantly enhanced plant growth parameters, including plant height, number of leaves, fresh weight, and dry weight, compared to the control. Additionally, most CRU fertilizers increased total yield and fruit characteristics (weight, length, and diameter) compared to the control. Additionally, marketable yield was improved by CRU fertilizers. Fruit firmness and acidity of CRU treatments at 25 and 50% N levels were much higher than both the 100% CRU treatment and the control. The vitamin C values of all CRU treatments were lower than the control. Nitrogen uptake efficiencies (NUpE) of CRU treatments were 47-88%, which is significantly higher than that of the control (33%). In conclusion, all CRU treatments at an N level of 25% of the recommended dose showed better plant growth, yield, and fruit quality of tomatoes than the conventional fertilizer.

Demonstrating an altered metal oxidation reaction mechanism correlated with variations in surface energy

Thermal processing of powder media such as annealing and quenching alters particle surface properties and can influence the powder's reactivity. In this study, thermogravimetric analysis (TGA) was performed with micro-sized (4 µm characteristic particle diameter) aluminum (Al) powder. Two powders were examined, namely, untreated Al (UN Al), i.e., procured from the manufacturer, compared with thermally processed Al by annealing and quenching (i.e., called super-quenched aluminum, SQ Al). TGA experiments were designed to compare the rate of oxidation of both materials. A new data processing technique was introduced that allows for a direct demonstration of altered reactivity by comparing the sample behavior during heating and cooling. The approach analyzes a normalized derivate drop of mass gain data throughout a programmed heating and cooling cycle depending on particle exposure time to oxygen at select temperatures. Results clearly confirm a difference between SQ Al and UN Al at temperatures around 600 °C, i.e., just below the Al melting temperature. The powders were also characterized using inverse gas chromatography (iGC) that showed a substantially higher surface energy of UN Al. Based on the experimental results, there is a correlation between Al reactivity and particle surface energy that substantiates recent observations of two different modes of Al particle combustion. Particle surface energy can be controlled to affect the mechanism for metal oxidation thereby affecting the rate of metal combustion.

Evaluation of Genetic Parameters of Growth Characteristics and Basic Density of Eucalyptus pellita Clones Planted at Two Different Sites in East Kalimantan, Indonesia

Eucalyptus pellita is one of the fast-growing tree species and has become predominant in Indonesian forest plantations. Meanwhile, tree breeding programs with clone development are the best way to provide greater genetic advantages. A better understanding of genetic control on growth and basic density in E. pellita is important for increasing wood productivity and quality. In this study, growth characteristics (tree height, diameter, and volume), basic density and its genetic parameters (heritability, genetic gain and genetic correlation) were determined. The number of clones tested in both trials was 50, divided into 5 blocks, and 5 trees/plot. The results showed that there were significant differences in growth and basic density among clones. There was an interaction between genetics and the environment further indicating the existence of unstable clones. The high heritability was found in tree height (0.82–0.86), diameter (0.82–0.90), and basic density (0.91–0.93). This implies that E. pellita has good opportunities for genetic improvement to increase wood productivity and quality. In addition, the results of genetic correlations among growth characteristics (height, diameter, and volume) and basic density showed positive moderate to highly significant value. It is suggested that these characters may be used to the advantage of the breeder for bringing improvement in these traits simultaneously. Therefore, this study provides important information of the genetic improvement of wood quality in E. pellita in Indonesia.

Development of Comprehensive Rating for the Evaluation of Sewer Pipelines

The Pipeline Assessment and Certification Program (PACP) was developed by the National Association of Sewer Service Companies, the industry-accepted protocol for condition rating sewer pipes in the US. The PACP method relies exclusively on visual inspections performed using closed-circuit television (CCTV), where certified operators observe existing structural and operation and maintenance (O&M) defects limitation of the PACP method is that it does not use pipe characteristics, depth, soil type, surface conditions, pipe criticality, and capacity, nor the distribution of structural defects or history of preventative maintenance to determine the condition rating of the sewer pipe segment. Therefore, this research addresses the limitations of the PACP with the development of a new wastewater pipe rating system known as the comprehensive rating (CR) system. The CR evaluation system is based on a commonly used decision-making approach known as the analytical hierarchy process (AHP) to analyze problems and issues. The new CR model incorporates pipe characteristics (age, corrosion, diameter, and shape), external characteristics (depth, soil type, traffic loading, waste type, seismic zone), and hydraulic characteristics (structural score, O&M score, and repair history). The results showed a below-average validity percentage because linear regression assumes a linear relationship between the input and output variables but the relationship between the response and the predictor is not linear.The CR methodology can be improved by increasing the number and variability of experts who evaluate the condition of existing sewer pipes, enhancing geospatial data for locational accuracy, and establishing evaluation standards for inspectors to minimize human error. More research is needed to determine a suitable nonlinear relation that can be used to model data from this new comprehensive rating system.

In-situ characterization of the size distribution of lubricant droplets in rotary compressor

Rotary compressors are widely used in split air conditioning units and have a significant global market share. However, the atomization of lubricant in the rotary compressor during discharge from the cylinder can cause negative effects on both heat transfer performance and reliability. Therefore, it is crucial to deepen the understanding of the behavior of atomized oil in the form of small droplets in order to improve the system’s performance. In this study, lubricant droplets were analyzed at different locations, operating frequencies, and pressures using shadowgraph imaging. The droplets were extracted using the Canny operator and corrected using a Convolutional Neural Network, and their sizes were analyzed statistically. The results reveal that the droplet characteristic mean diameters increase with frequency and pressure, with larger sizes observed in the outer region above the rotor/stator and constant sizes in the radial direction at the discharge tube level. Additionally, the droplet’s volume fraction increases with frequency, with higher values observed in the outer region above the rotor/stator and above the rotor/stator clearance at the discharge tube level. These findings provide valuable experimental data for setting up the boundary conditions used in computational fluid dynamics (CFD) simulations.

Long-term Evaluation of Proximal Aortic Neck Dilatation After Endovascular Abdominal Aortic Aneurysm Repair With a Variety of Contemporary Endografts

To measure the long-term proximal aortic neck dilatation (AND) after elective endovascular aortic aneurysm repair (EVAR) with a variety of contemporary, third-generation, endograft devices. This is a noninterventional prospective cohort study of 157 patients that underwent standard EVAR with self-expanding abdominal endografts. Patients' recruitment lasted from 2013 to 2017, and postoperative follow-up was up to 5 years. A computed tomography angiography (CTA) was performed at the first month and then at 1, 2, and 5 years. Proximal aortic neck's (PAN) basic morphological characteristics (diameter, length, angulation) were measured based on the analysis of CTA in a standardized fashion. Neck-related adverse events, such as migration, endoleak or rupture, and reinterventions were recorded. Significant straightening of the PAN was evident even in the first-month CTA with concurrent neck shortening that became significant at 5 years. Both the suprarenal aorta and the PAN significantly dilated overtime, with PAN dilating more progressively. Mean neck dilatation at the juxtarenal level was 0.8±0.4 mm at 1 year, 1.8±0.8 mm at 2 years, and 3.9±1.7 mm at 5 years, with a mean neck dilatation rate of 0.07 mm/month overall. The incidence of AND ≥2.5 mm was 37.2% at 2 years and 58.1% at 5 years after EVAR and was considered important (≥5 mm) in 11.5% of patients at 2 years and 30.6% of patients at 5 years. A multivariate analysis performed showed that the endograft oversizing, the preoperative neck diameter, and the preoperative abdominal aortic aneurysm sac diameter served as independent predictors of AND at 5 years. At the 5-year follow-up, 8 late type Ia endoleaks (6.5%) and 7 caudal migrations (5.6%) were identified, while no late ruptures were reported. In total, 11 late endovascular reinterventions (8.9%) were performed. Overall, proximal neck-related adverse outcomes (5/7 migrations and 5/8 endoleaks) and reinterventions (7/11) were significantly associated with the presence of important late AND. Proximal AND after EVAR is common. It can influence the long-term durability of proximal endograft fixation and is significantly associated with adverse outcomes, often leading to reinterventions. A systemic and extended surveillance protocol is needed for maintenance of good long-term results. This is a thorough and systematic analysis of the long-term geometric remodeling of the proximal aortic neck after EVAR, that highlights the importance of a strict, and extended surveillance protocol for maintenance of good long-term results of EVAR.

Bioluminescent eddies of the World Ocean.

Mesoscale eddies of the ocean (with a characteristic diameter of about one hundred km and a life time span of about several weeks) are habitats of plankton organisms, many of which are bioluminescent. The spatial heterogeneity of bioluminescence of the upper mixed layer associated with the impact of mesoscale eddies is poorly studied. The 45-year historical data set was retrieved, in order to select the bathy-photometric surveys carried out in the form of station grids and transects across eddies. Data from 71 expeditions deployed in 1966-2022 to the Atlantic Ocean, Indian Ocean and Mediterranean Sea basin were analyzed, in order for the spatial heterogeneity of bioluminescent fields to be elucidated across eddy fields. The stimulated bioluminescence intensity was characterized by the bioluminescent potential, which represented the maximal amount of radiant energy emitted in a given volume of water by bioluminescent organisms. The normalized bioluminescent potential over oceanographic station grids exhibited correlation with the eddy kinetic energy and zooplankton biomass (r =0.8, at p=0.001 and r =0.7, at p=0.05, respectively), in a broad range of energy and bioluminescence units (0.02-0.2 m2 s-2 ; 0.4-92.0*10-8 W cm-2 L-1 , respectively). Overall, estimates of bioluminescent potential variability on the mesoscale contribute to the assessment of the multiple-scale variation of the bioluminescent field of the World Ocean.

The effect of stevia powder on the quality of gluten-free cookies

The paper presents the results of studies of the effect of stevia powder on the quality of gluten-free cookies with a complete replacement of sugar in the recipe. The cookies were made from a mixture of rice and corn flour (40/60). Margarine or vegetable oil were used as fat components. Stevia powder was used in different amounts: 1.0; 2.0; 3.0%. Cookies quality were assessed by organoleptic indicators, physical characteristics (diameter, thickness), moisture, swelling, strength on the structure analyzer "Structurometer ST-2". When completely replacing sugar with stevia powder in various amounts, margarine cookies were comparable in size to sugar cookies, while increasing moisture, but reducing swelling and strength values. Replacing the fat component with vegetable oil resulted in the formation of a flatter, more brittle cookie, with pronounced brittleness, which was reflected in its strength, both in cookies with sugar and with stevia. The use of guar or xanthan gum in the formulation of gluten-free cookies with stevia and vegetable oil made it possible to obtain softer cookies, increased their thickness, as well as moisture and swelling, stabilized the strength, which became comparable before the addition of stevia powder. An increase in the amount of gum over 1% led to large changes in cookie quality indicators, and depended on the type of gum, which was more pronounced when using xanthan gum. The main criterion for the quality of gluten-free cookies with stevia powder in the amount of 1.0% was the minimum specific sweetness

Drop Size Measurement Techniques for Agricultural Sprays:A State-of-The-Art Review

Plant protection control based on the spray application of plant protection products is a very complex task depending on a series of factors, among which droplet size is the most influential for deposition and pesticide effectiveness. In fact, the adoption of the correct droplet size can ensure that the required dose reaches the target area and is not wasted, minimizes the off-target losses due to evaporation, drift and run-off and, at the same time, enhances the operator’s safety in terms of inhalation, ingestion and dermal exposure. In this paper, after defining some mean characteristic diameters helpful for a description of a drop population and focusing on the main drop size distribution functions for the statistical characterization of sprays, a critical analysis of known methods, both intrusive and non-intrusive, for drop size measurement is carried out by reviewing the literature. Among intrusive methods, the liquid immersion method and the use of water-sensitive papers are discussed, whereas, among non-intrusive methods, laser-based systems (laser diffraction, phase Doppler particle analysis) and high-speed imaging (shadowgrapy) are presented. Both types of method, intrusive and non-intrusive, can be used in machine-learning-based approaches exploiting regression techniques and neural network analysis.

Urban heat dome flow deflected by the Coriolis force

An urban heat dome forms over urban areas when synoptic winds are weak, which is widely seen during heatwaves and expected to become the ‘norm’ in the future due to climate change. The spatial and aerodynamic characteristics of the urban heat dome have a direct impact on city-scale heat distribution and associated building cooling energy demand and many human-environment interaction processes. As the hydraulic diameter of a city goes beyond 20 km, the Coriolis force that can deflect the flow of the heat dome comes into play. Our large-eddy simulations of a 400 km2 idealized square city show that the flow of the heat dome is markedly deflected by the Coriolis force. In the Northern hemisphere, the near ground convergence inflow is found to be drastically deflected counter-clockwise. At higher levels above ground, deflected airflow leaving the city center emerges gradually, and an anticyclone is eventually seen. The findings imply that, when urban characteristic diameter reaches beyond 10 km, the deflection of the urban heat dome in high-latitude regions has to be considered in order to understand city-scale heat transport at high-spatial resolution and to underpin the development of fine-tuned measures for local urban heat mitigation.

Linear frequency modulation infrared thermal imaging detection technology for GFRP/PMI foam sandwich structure defects

As one of the important structures of composite materials, polymethacrylimide (PMI) foam sandwich structure is prone to debonding and delamination defects during manufacturing and service, which seriously affects the mechanical properties of materials. Therefore, it is necessary to detect the defects of foam sandwich structure. A linear frequency modulation infrared thermal wave nondestructive testing system was built to study the correlation between the geometric characteristics (diameter and depth) of the defect and the surface temperature signal and its influence on the detection effect. The image sequence is processed by principal component analysis, discrete Fourier transform, thermal wave signal reconstruction, and other algorithms. Studies have shown that the larger the defect diameter, the shallower the depth, easy to detect defects, detection effect is good. The detection system can effectively detect and identify debonding and de-lamination defects. The thermal wave signal reconstruction method is superior to the principal component analysis method and the discrete Fourier transform method in the signal-to-noise ratio index, which improves the quality of the image and is conducive to the effective identification of the image surface defect information.