Search

Under earthquake loads, reinforced concrete chimneys with openings are prone to stress concentration and damage around these openings, possibly leading to structural collapse. In this paper, the stress concentration factor was proposed to quantitatively analyse the range of stress concentrations around openings under various parameters and identify the most significant coefficients affecting the stress concentration range. 9 Groups of numerical analysis models for chimneys with different parameterized openings were established, and more than 200 pushover analyses were conducted. The effects of the chimney wall thickness, wall diameter, opening size, and spacing between openings on the stress around the openings were investigated. Recommendations for limiting opening sizes were given, and a method for designing reinforcement steel bars for strengthening was proposed. The numerical results indicated that the central angle of a single opening cross-section should be less than 70°, and the total central angle of multiple openings should be less than 140°; the spacing between openings should not be less than 0.5 times the width of the opening; the range of the steel reinforcement range should be 4.5 times the wall thickness for circular openings; and for rectangular openings, it should be 3.5 times the wall thickness. The added reinforcement steel should have a reinforcement ratio for strengthening of 1.3 times that of the original reinforcement ratio. Finally, through dynamic analysis, it was verified that the opening reinforcement design method proposed in this paper can effectively reduce the stress concentration around openings. [ABSTRACT FROM AUTHOR]

Traditional methods for measuring chemical exposure have challenges in terms of obtaining sufficient data; therefore, improved methods for better assessing occupational exposure are needed. One possible approach to mitigate these challenges is to use self-monitoring methods such as sensors, diaries, or biomarkers. In the present study, a self-monitored method for measuring soot exposure, which included real-time air monitoring, a work diary, and the collection of urine samples, was evaluated. To validate the method, exposure measurements during the workday and diary entries were compared with velocities calculated from GPS tracking and the expected polycyclic aromatic hydrocarbon (PAH) metabolite patterns in urine. The method was applied with chimney sweeps, an occupational group at a high risk of many severe health outcomes and for whom effective control measures for reducing exposure are needed. In the study, 20 chimney sweeps followed a self-monitoring protocol for 8 consecutive workdays. Personal exposure to soot was measured as black carbon (BC) using micro-aethalometers. A diary was used to record the work tasks performed, and urine samples were collected and analysed for PAH metabolites. From the expected 160 full day measurements, 146 (91%) BC measurements and 149 (93%) diaries were collected. From the expected 320 urine samples, 304 (95%) were collected. The tasks noted in the diaries overlapped with information obtained from the GPS tracking of the chimney sweeps, which covered 96% of the measurement time. The PAH metabolites in urine increased during the work week. Factors believed to have positively influenced the sample collection and task documentation were the highly motivated participants and the continuous presence of trained occupational hygiene professionals during the planning of the study and throughout the measurement stage, during which they were available to inform, instruct, and address questions. In conclusion, the self-monitored protocol used in this study with chimney sweeps is a valuable and valid method that can be used to collect larger numbers of samples. This is especially valuable for occupations in which the employees are working independently and the exposure is difficult to monitor with traditional occupational hygiene methods. [ABSTRACT FROM AUTHOR]

Submarine pockmarks are typical indicators of submarine gas escape activity. The deep strata of the Xisha Uplift are rich in biogenic and thermogenic gas, accompanied by strong bottom current activity. Investigating the effects of controlling submarine gas escape and bottom current activity on the formation and development of pockmarks in the Xisha Uplift is significant for understanding the evolution of submarine topography and geomorphology. This study utilized high-resolution multibeam data to identify 261 submarine pockmarks in the northwest of the Xisha Uplift. These pockmarks were categorized based on their morphology into circular, elliptical, elongated, crescent-shaped, and irregular types. The diameters of pockmarks in the study area range from 0.21 to 4.96 km, with maximum depths reaching 30.88 m. Using high-resolution multi-channel seismic data, we conducted a detailed analysis of the subsurface strata characteristics of the pockmarks, identifying chaotic weak reflections, bright spots, and high-angle reflectors. We believe that deep gas in the northwest of the Xisha Uplift escapes to the seafloor through migration pathways, such as faults, fractures, and gas chimneys, resulting in the formation of submarine pockmarks. Bottom current activity has a significant impact on already-formed pockmarks. Crescent-shaped and elongated pockmarks in the Xisha Uplift are largely the result of bottom current modifications of pre-existing pockmarks. [ABSTRACT FROM AUTHOR]

Polychlorinated Dibenzo-p-Dioxins/Furans (PCDDs/Fs) were investigated for their relocation properties and adverse effects for chimneys air-flue emissions of charcoal-grilled meat restaurants in Jordan. Restaurants were given the codes (S, Z, G, B, and J). Levels of PCDDs/Fs depend on the quantity of used charcoal, amount of grilled meat, and sampling season. The PCDD/Fs compounds were extracted from the filter using the QuEChERS and detected in extracts using GC/MS. The results showed that PCDD/Fs concentrations in international toxic equivalents (I-TEQs) in (ng I- TEQ/m3) were found in the following order: S restaurant (87.03) > B (7.24) > G (4.90) > J (3.36) > Z (0.54) where some samples contained 2, 3, 7, 8-TCDD in considerable amounts. The emitted concentrations of PCDD/Fs through chimneys were found to depend on many factors that were measured such as type and quantity of grilling fuels, amount quantities of grilled food after marinating and sampling season. This study is featured as the first of its kind in the Middle East and North Africa that reveals the dangers of using charcoal for grilling because it causes contamination of food and air. It also calls for advising people to minimise the consumption of grilled food since it will contain a portion of carcinogenic (group 1) 2,3,7,8-TCDD. Charcoal-grilled restaurants are worldwide and part of international cuisine. [ABSTRACT FROM AUTHOR]

We consider the standard first passage percolation model on Z d with a distribution G taking two values 0 < a < b . We study the maximal flow through the cylinder [ 0 , n ] d - 1 × [ 0 , h n ] between its top and bottom as well as its associated minimal surface(s). We prove that the variance of the maximal flow is superconcentrated, i.e. in O (n d - 1 log n) , for h ≥ h 0 (for a large enough constant h 0 = h 0 (a , b) ). Equivalently, we obtain that the ground state energy of a disordered Ising ferromagnet in a cylinder [ 0 , n ] d - 1 × [ 0 , h n ] is superconcentrated when opposite boundary conditions are applied at the top and bottom faces and for a large enough constant h ≥ h 0 (which depends on the law of the coupling constants). Our proof is inspired by the proof of Benjamini–Kalai–Schramm (Ann Probab 31:1970–1978, 2003). Yet, one major difficulty in this setting is to control the influence of the edges since the averaging trick used in Benjamini et al. (Ann Probab 31:1970–1978, 2003) fails for surfaces. Of independent interest, we prove that minimal surfaces (in the present discrete setting) cannot have long thin chimneys. [ABSTRACT FROM AUTHOR]

Hydrothermal vents host a diverse community of microorganisms that utilize chemical gradients from the venting fluid for their metabolisms. The venting fluid can solidify to form chimney structures that these microbes adhere to and colonize. These chimney structures are found throughout many different locations in the world's oceans. In this study, comparative metagenomic analyses of microbial communities on five chimney structures from around the Pacific Ocean were elucidated focusing on the core taxa and genes that are characteristic of each of these hydrothermal vent chimneys. The differences among the taxa and genes found at each chimney due to parameters such as physical characteristics, chemistry, and activity of the vents were highlighted. DNA from the chimneys was sequenced, assembled into contigs, and annotated for gene function. Genes used for carbon, oxygen, sulfur, nitrogen, iron, and arsenic metabolisms were found at varying abundances at each of the chimneys, largely from either Gammaproteobacteria or Campylobacteria. Many taxa shared an overlap of these functional metabolic genes, indicating that functional redundancy is critical for life at these hydrothermal vents. A high relative abundance of oxygen metabolism genes coupled with a low abundance of carbon fixation genes could be used as a unique identifier for inactive chimneys. Genes used for DNA repair, chemotaxis, and transposases were found at high abundances at each of these hydrothermal chimneys allowing for enhanced adaptations to the ever-changing chemical and physical conditions encountered. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the problem of source recovery in a dynamical system utilizing space-time samples. This is a specific issue within the broader field of dynamical sampling, which involves collecting samples from solutions to a differential equation across both space and time with the aim of recovering critical data, such as initial values, the sources, the driving operator, or other relevant details. Our focus in this study is the recovery of unknown, stationary sources across both space and time, leveraging space-time samples. This research may have significant applications; for instance, it could provide a model for strategically placing devices to measure the number of pollutants emanating from factory smokestacks and dispersing across a specific area. Space-time samples could be collected using measuring devices placed at various spatial locations and activated at different times. We present necessary and sufficient conditions for the positioning of these measuring devices to successfully resolve this dynamical sampling problem. This paper provides both a theoretical foundation for the recovery of sources in dynamical systems and potential practical applications. [ABSTRACT FROM AUTHOR]

Gas chimneys and gas clouds in the subsurface media are known as one of the indications of possible petroleum reservoirs. Investigations of their properties are mostly initiated by seismic attribute interpretation on reflection seismic data. However, due to the complexity of their behavior and their difficult interpretation of seismic attributes, state-of-the-art methods are mostly required to be applied on the seismic data to prevent any misinterpretation. This is mostly done through attribute integration and multi-attribute analysis. This research presents a study on seismic attributes and integration on several 2D seismic reflection lines from the Gorgan Plain. It is located in Northeast Iran, on the western border of the region's well-known Kopeh-Dagh fold and thrust belt, and southeastern border of the South Caspian Basin. Hydrocarbon systems of the Gorgan Plain are poorly known and have not been widely studied, but according to preliminary investigations, this region has the potential for hydrocarbon occurrences. The aim of this study is to investigate presence and then delaminate the affected area of possible gas chimneys that are related to possible hydrocarbon reservoirs. Gas chimneys are assumed to be created due to the routes, mostly made by faults, that provoke light hydrocarbons components to migrate toward the surface. Preliminary interpretations of seismic reflection data in this study revealed that at least two gas chimneys occurred within the Gorgan Plain. As it was mentioned, since they are mostly due to the faulting above the hydrocarbon reservoir, gas chimney and heavy faulting might exhibit the same effects on the seismic data and then on its attributes, which are amplitude reduction and high damping on energies, distortion of the waveshape and seismic velocity reduction. Thus, care should be taken in separation of these two different geologic phenomena on seismic attributes. This also was done in this study through utilized integration of the most relevant seismic attributes such as Instantaneous-phase, Chaos, Variance and Remove-bias attributes. Based on the result of interpretations and according to the evolution of the basin and its structural reconstruction on other studies, gas chimneys of the Gorgan Plain, are in relation to the operation of fault zones in Cenozoic erathem in the region. These fault zones which cut the entire Cenozoic erathem, create the pathway for vertical migration of hydrocarbons through Cheleken formation (reservoir rock) and its overburden sedimentary sequences. In other words, operation of fault zones within Cenozoic sedimentary sequence, is the main reason for gas seepage in the Gorgan Plain, which is also shown in seismic data. [ABSTRACT FROM AUTHOR]

This document discusses the importance of the thermal performance of building envelopes in achieving energy efficiency and indoor comfort. It highlights the need for a strategic selection of building materials based on their thermal properties and performance. The document presents various methods for assessing the thermal performance of building envelopes, including nondestructive techniques, experimental measurements, and numerical analyses. It also explores the integration of renewable energies into building envelopes and the optimization of energy in buildings. The document concludes by suggesting future research directions, such as the development of advanced materials and the use of digital twins and hybrid simulation models. The document includes contributions from scholars from various countries, promoting diverse perspectives on the topic. [Extracted from the article]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Methane is a potent greenhouse gas that enters the marine system in large quantities at seafloor methane seeps. At a newly discovered seep site off the coast of Point Dume, CA, ~ meter‐scale carbonate chimneys host microbial communities that exhibit the highest methane‐oxidizing potential recorded to date. Here, we provide a detailed assessment of chimney geobiology through correlative mineralogical, geochemical, and microbiological studies of seven chimney samples in order to clarify the longevity and heterogeneity of these highly productive systems. U‐Th dating indicated that a methane‐driven carbonate precipitating system at Point Dume has existed for ~20 Kyr, while millimeter‐scale variations in carbon and calcium isotopic values, elemental abundances, and carbonate polymorphs revealed changes in carbon source, precipitation rates, and diagenetic processes throughout the chimneys' lifespan. Microbial community analyses revealed diverse modern communities with prominent anaerobic methanotrophs, sulfate‐reducing bacteria, and Anaerolineaceae; communities were more similar within a given chimney wall transect than in similar horizons of distinct structures. The chimneys represent long‐lived repositories of methane‐oxidizing communities and provide a window into how carbon can be transformed, sequestered, and altered over millennia at the Point Dume methane seep. [ABSTRACT FROM AUTHOR]

Population growth, increase in energy demand, and environmental problems of fossil fuels have led to the use of renewable energies. One of the applications of solar energy is the solar chimney thermal power plant. Building a solar chimney is not cost-effective due to its low thermal efficiency, so studies have been conducted to increase its efficiency. Among the studies conducted, few have studied the influence of absorber geometry on system performance. In this research, the solar chimney was designed in small dimensions and effect of changing the geometry of the absorbent surface was investigated. The numerical model has been validated with experimental data of Manzanares pilot plant. The geometry was numerically simulated in Ansys Fluent software. Realizable k-ε model for turbulence and DO irradiation model for radiation has been used. The solar radiation 1000 W / m 2 is selected. The coupled arithmetic was used as the pressure–velocity coupling scheme. Besides, the discretization method for the pressure term was PRESTO! Algorithm while other terms were second-order. The criterion of convergence in solving all equations is 10 - 6 . The results showed that the maximum velocity for height 0.1 and 0.2 m has increased by 6.945% and 8.048%, respectively, compared to the smooth absorber surface. By increasing the height in the center of the solar chimney, the maximum power is obtained at a height of 0.2 m with a value of 2.338 w. Therefore, changing the geometry of the absorber affects the performance of the chimney and can strengthen it. [ABSTRACT FROM AUTHOR]

The conventional Mohr–Coulomb (M-C) failure criterion is commonly used in existing studies to determine the ultimate pullout capacity of plate anchors buried in cohesive-frictional soils. However, this criterion overestimates the tensile strength of these soils by assuming a linear failure envelope (in both compression and tensile regimes) within the normal-shear stress space. In this study, the ultimate pullout capacity of horizontally buried plate anchors in cohesive-frictional soils was determined, accounting for the effect of tensile strength cutoff. The study proposed a series of semianalytical solutions utilizing the kinematic horizontal slice approach and investigated the ultimate pullout capacity of four different anchor shapes, including circular, square, rectangular, and strip anchors. The impact of nonassociated flow rule on the results was also examined. It has been observed that the results obtained using the M-C failure criterion with a tension cutoff are significantly lower than those obtained using the conventional M-C failure criterion. The difference between both results increases as soil cohesive strength increases and anchor burial depth decreases. These findings clearly demonstrate that eliminating tensile strength from the strength envelope leads to a more conservative estimate of plate anchor pullout capacity. The study emphasizes changes in anchor failure surfaces for various parameter combinations and provides results that are consistent with specific solutions reported in the literature. Practical Applications: The study investigates using plate anchors to enhance the stability of both onshore and offshore structures, including transmission towers, guyed masts, chimneys, and mooring platforms. These structures often encounter significant vertical pullout forces. The research establishes a theoretical framework for calculating the ultimate vertical pullout capacity of plate anchors with various shapes (strip, rectangular, and circular) when buried in cohesive-frictional soils. A crucial aspect of this analysis involves incorporating the specified/limited value of tensile strength in cohesive-frictional soils when assessing the ultimate pullout capacity of plate anchors. This consideration is vital for ensuring a safe and conservative design, especially for structures subject to uplift forces. The findings provide valuable insights for engineers and practitioners, offering a reliable method to optimize the usage of plate anchors in the design of pullout-resistant structures. [ABSTRACT FROM AUTHOR]

The centralized smoke exhaust system of shield tunnel is an important determinant for tunnel fire safety, and the use of different design parameters of the tunnel smoke exhaust system will affect the smoke exhaust effect in the tunnel, and the influence of different design parameters on the smoke exhaust effect and temperature attenuation of the tunnel can help engineers in designing a more effective centralized smoke exhaust system for the tunnel. In this paper, the Fire Dynamic Simulator (FDS) is utilized to examine smoke exhaust vent settings for a centralized exhaust system in shield tunnel with both flat and sloped conditions, including slopes of +4.5% and −4.5%, under a 30 MW fire power with a 150 m/s smoke exhaust rate. The results suggest that maintaining a vent spacing of 60 m and a vent size of 4.0 m × 1.5 m is a reasonable configuration for centralized smoke exhaust systems in both flat and slope shield tunnels. This choice helps minimize construction costs and prevent excessive smoke accumulation. It also promotes favorable conditions for maintaining temperature distribution at 2-m height, visibility, smoke spread distance, and temperature below the ceiling, all below the threshold values, while ensuring high smoke extraction efficiency. However, in the slope section, the chimney effect can disrupt exhaust efficiency, visibility, ceiling temperature, and temperature distribution at a height of 2 m. Employing different opening methods, such as having 2 vents up and 4 vents down in a +4.5% slope and 4 vents up and 2 vents down in a −4.5% slope, can help mitigate these effects. Furthermore, the temperature decay formula for shield tunnels follows a bi-exponential decay pattern, and different design parameters of centralized smoke exhaust systems have minimal effects on temperature decay in shield tunnels. [ABSTRACT FROM AUTHOR]

This paper presents the results of the measurements of gamma radioactive isotopes in soot samples from 15 different chimneys of household furnaces fired with various types of solid fuel. Soot samples were collected by the chimney sweep during the mandatory periodic cleaning of the chimneys. The γ-spectrometry technique using the high-purity germanium (HPGe) detector was employed for radiometry of the above-mentioned soot. It was found that the determined activity of gamma isotopes in soot is at a level similar to that in fly ash from power plants around the world. Artificial 137Cs was detected only in the soot from the combustion of biofuel or mixed fuel. The results obtained were chemometrically analyzed to find the relationship between the fuel used and the gamma isotope content in the soot. The analysis of 137Cs, 40K, 228Th, and 226Ra is sufficient to differentiate between the soot obtained and tested, and it varied with the fuel type burned (fossil fuels/biofuels). [ABSTRACT FROM AUTHOR]

The research and management of Industry 4.0 increasingly relies on accurate real-time quality data to apply efficient algorithms for predictive maintenance. Currently, Low-Power Wide-Area Networks (LPWANs) offer potential advantages in monitoring tasks for predictive maintenance. However, their applicability requires improvements in aspects such as energy consumption, transmission range, data rate and constant quality of service. Commonly used battery-operated IIoT devices have several limitations in their adoption in large facilities or heat-intensive industries (iron and steel, cement, etc.). In these cases, the self-heating nodes together with the appropriate low-power processing platform and industrial sensors are aligned with the requirements and real-time criteria required for industrial monitoring. From an environmental point of view, the carbon footprint associated with human activity leads to a steady rise in global average temperature. Most of the gases emitted into the atmosphere are due to these heat-intensive industries. In fact, much of the energy consumed by industries is dissipated in the form of waste heat. With this scenario, it makes sense to build heat transformation collection systems as guarantors of battery-free self-powered IIoT devices. Thermal energy harvesters work on the physical basis of the Seebeck effect. In this way, this paper gathers the methodology that standardizes the modelling and simulation of waste heat recovery systems for IoT nodes, gathering energy from any hot surface, such as a pipe or chimney. The statistical analysis is carried out with the data obtained from two different IoT architectures showing a good correlation between model simulation and prototype behaviour. Additionally, the selected model will be coupled to a low-power processing platform with LoRaWAN connectivity to demonstrate its effectiveness and self-powering ability in a real industrial environment. [ABSTRACT FROM AUTHOR]

In this study, an experimental model of a photovoltaic (PV) solar chimney (SC) was built and study the extent to which the asphalt material, being a phase‐change material, affects its performance electrical and thermal. Results were taken for the two systems: The photovoltaic solar chimney which contains phase change material (SCPV‐PCM), and the photovoltaic solar chimney which does not contain phase change material (SCPV). The finding demonstrated that the PCM affects the SCPV electrical and thermal performance; the results were as follows: The electrical power for the SCPV‐PCM system increased during the day and its highest value at noon was 384.34 W, and then it began to decrease. The SCPV system had a higher power at the end of the test, 73.24 W, due to the lower temperature of the PV panel. The highest electrical efficiency was for the SCPV‐PCM system at the beginning of the test, reaching the highest value of 13.12%, then it decreased at the end of the test to be less than the SCPV system at 5:00 pm. The thermal efficiency of the SCPV‐PCM arrangement is lesser than the arrangement that does not contain PCM, reaching its highest value at noon, which was 57.1% for the SCPV system. The total efficiency of the SCPV‐PCM system is lesser than the SCPV system from the beginning of the test until 3:30 pm approximately, reaching its highest value of 68.05% at noon. [ABSTRACT FROM AUTHOR]

A big hurdle to using solar chimneys for power generation is their low overall efficiency, which is measured by how effectively energy is converted at different stages of the system. While a taller chimney might help, it is expensive and complex to implement. To address this issue, a new study explored the possibility of using a thermal absorbing assembly at the top of the chimney to increase its efficiency without increasing its height. The study presented both experimental and numerical data on this approach, looking at changes in temperature and heat gains as performance indicators. By adding this low-cost and simple fixture, the study found that the temperature before the chimney outlet increased, and the stack effect was strengthened. The rise of air temperature posed an increase of up to 83.1% by experimental assessment and an increase of 12.75% by numerical assessment with the added fixture of the heat trap. [ABSTRACT FROM AUTHOR]

Copyright of Materiały Budowlane is the property of Wydawnictwo SIGMA-NOT and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The chimney junction of solar chimney power plant was the main element coupled the solar collector to the chimney. It presents an important impact on the SCPP design, which is change the air-flow direction. The numerical code ANSYS Fluent was used in this study to investigate how the chimney Junction radius affected the local air-flow characteristics and the turbine site. Using test results from an experimental prototype constructed in Sfax, Tunisia, the numerical method was validated and verified. For four set-ups with various chimney connection radii, thermodynamic variables such as distributions of the total pressure, static temperature, static pressure, and magnitude velocity were examined. Also, the influence of these parameters on the air turbulence was analyzed through the transition zone. The results showed that the local air-flow characteristics and therefore, the SCPP efficiency were significantly impacted by changes in junction radius. Besides, the maximum velocity inside the chimney was varied and changes its location when the junction radius changed. These facts affect directly the overall turbine expenditure, which represented in terms of structure and power capacity. [ABSTRACT FROM AUTHOR]

In order to augment cooling performance of transformer panel-type radiators under natural-convection, the fluid-flow and heat transfer for a novel panel-type radiator and its surrounding air are numerically studied in this paper. The novel radiator is equipped with wind deflectors on both lateral sides and a chimney cap on the top. Then the effects of the height and channel number of the chimney cap on the cooling performance of the radiator are simulated. The results show that wind deflectors can form several enclosed air channels with radiator fins. The airflow can be accelerated under the chimney effect generated in these channels, and the cooling capacity of the radiator can be increased by 12.75%. The addition of a chimney cap can further extend the chimney channels and increase its cooling capacity by 15.74%. Furthermore, with the increase of the height and channel number, the total cooling capacity of the panel-type radiator increases first and then decreases. In this study, when the chimney cap has five channels and a height of 700 mm, the novel radiator can obtain the best cooling performance, where its cooling capacity and overall heat transfer coefficient can be increased by 26.54% and 28.21%, respectively, as compared with traditional panel-type radiators, and the temperature difference between the inlet and outlet insulating oil is 7.1 °C. [ABSTRACT FROM AUTHOR]

In glass industry, the evolved gases and fumes from burning the gas fuel absorbed in calcium hydroxide to minimize the pollution of environment. After a period of time, the calcium hydroxide fouled with sulphate and carbonate as action of the absorbed SO3 and CO2 gases. Based on our interest to treatment the solid waste materials, this study intended to convert the obtained waste of calcium hydroxide fouled with gases to valuable products. Firstly, this waste was treated with water, caustic soda and acids. The results confirmed the conversion of waste to pure calcium sulfate by treatment with 6 v/v% sulfuric acid. Secondly, the obtained calcium sulfate was reacted with ammonium dihydrogen phosphate solution for preparation of calcium hydroxyapatite (HAp) nanoparticles. The produced HAp sample was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and N2 adsorption measurements. The obtained findings confirmed that the HAp can be produced after calcination at 700 °C, nanorods-like of sizes ranged from 11 to 15 nm and with main surface functional groups of hydroxyapatite. TGA and DTA data indicated that HAp is thermally stable up to 700 °C. Also, the obtained HAp has Ca/P molar ratio of 1.60 and exhibited high total surface area of 146 m2/g with mesoporous structure which make this material can be used in medical and water purification applications. [ABSTRACT FROM AUTHOR]

A TLD is a passive damping device that works by dissipating energy through the sloshing of the liquid and the effect of wave breaking, thereby controlling the vibrations of the structure. One of the applications where TLDs are of great interest is in the case of industrial chimneys since these structures often have a very low natural frequency, which can be easily achieved in a control device of this type. The main objective of this study is to evaluate the behaviour of an annular TLD composed of multiple cells through laboratory tests and investigate if it is adequate to design it as an agglomeration of smaller rectangular TLDs. The influence of the amplitude of displacement on the behaviour of the annular TLD will also be analysed. The tests were performed on a shaking table and recurring with pendulums of the same length but of different masses. Three reservoirs were studied as TLDs: a rectangular one, a cell of an annular TLD and a quarter-ring of an annular TLD. This study concluded that the analytical methods developed in previous studies were, in general, adequate for the design of a rectangular TLD and that it was reasonable to design the annular TLD studied as a combination of rectangular ones, as its cells were a close match to a rectangle of similar dimensions. It was also concluded that a compartmentalised annular TLD is an adequate solution for the vibration control of structures with high displacements. [ABSTRACT FROM AUTHOR]

Submarine hydrothermal venting leads to the formation of black smoker chimneys with complex internal zoning. These emerge through mineral precipitation under changing fluid conditions caused by variable degrees of fluid-seawater mixing. This study explores the potential of selenium (Se) isotopes as a novel tool to understand the enrichment processes and identify the sources of chalcophile elements in seafloor hydrothermal systems. In-situ trace element analysis of hydrothermal sulfides combined with high-precision Se and S isotope analysis of micro-domains through the wall of black smoker chimneys from the Nifonea vent field (New Hebrides back-arc, SW Pacific) revealed variations in sulfide chemistry at small spatial resolution. The δ82/76Se values (deviation of 82Se/76Se relative to NIST SRM 3149) of the sulfide micro-domains range from +0.6 to −3.7 ‰ ± 0.2 ‰ (2 s.d.) with a general decrease from the inner chalcopyrite lining towards the outer chimney wall. The highest δ82/76Se values overlap with the mean value of fresh basaltic glass from Nifonea caldera (+0.6 ± 0.4 ‰, n = 4), indicating that Se is primarily leached from the surrounding back-arc basalts. The trace element contents of sulfides revealed systematic variations between vent sites, linked to differences in fluid vapor content induced by sub-seafloor boiling, which did not cause any Se isotope fractionation. Instead, decreasing Se/Tl ratios of pyrite together with decreasing δ82/76Se values of sulfide micro-domains and calculated δ34S H2S fluid values towards the outer chimney wall are indicative of temperature-dependent Se and S isotope fractionation at 370 to <200 °C during fluid-seawater mixing within the chimney wall. This study presents Se isotopes as a new robust instrument to unravel the sources of chalcophile elements and related fluid processes in seawater-diluted hydrothermal systems, enhancing our understanding of their geochemical complexities. [ABSTRACT FROM AUTHOR]

A stratigraphic complex composed of mass transport deposits (MTDs), where the gas occurrence allows for the formation of a gas chimney and pipe structure, is identified based on seismic interpretation in the QiongDongNan area of the northern South China Sea. During the Fifth Gas Hydrate Drilling Expedition of the Guangzhou Marine Geological Survey, this type of complex morphology that has close interaction with local gas hydrate (GH) distribution was eventually confirmed. A flow-reaction model is built to explore the spatial–temporal matching evolution process of massive GH reservoirs since 30 kyr before the present (BP). Five time snapshots, including 30, 20, 10, and 5 kyr BP, as well as the present, have been selected to exhibit key strata-evolving information. The results of in situ tensile estimation imply fracturing emergence occurs mostly at 5 kyr BP. Six other environmental scenarios and three cases of paleo-hydrate existence have been compared. The results almost coincide with field GH distribution below the bottom MTD from drilling reports, and state layer fracturing behaviors always feed and probably propagate in shallow sediments. It can be concluded that this complex system with 10% pre-existing hydrates results in the exact distribution and occurrence in local fine-grained silty clay layers adjacent to upper MTDs. [ABSTRACT FROM AUTHOR]

The operator of Chimney Rock Dam observed the emergence of increasing seepage at the toe of the dam when the water level in the reservoir exceeded a particular elevation. However, the source and the pathways of the seepage were not identified. To address this issue, integrated geophysical methods were employed to delineate the different units of the dam embankment and identify potential seepage zones and pathways. The methods utilized in this study included electrical resistivity tomography (ERT), self-potential (SP), and multichannel analysis of surface waves (MASW). The ERT profiles revealed variations in the dam's fill properties, including areas with anomalously low resistivity, interpreted as zones of relatively high moisture content. The two long SP profiles conducted along the dam embankment displayed similar spatial correlations with these low-resistivity zones, suggesting potential preferential seepage pathways. The SP map generated from a suite of parallel SP profiles conducted over the abutment depicts a pattern of positive background and negative potential anomalies, which may suggest fluid movement or seepage potential. The MASW profile along the top of the dam characterized an upper low shear-wave velocity layer corresponding to the top dry section of the embankment underlain by a higher shear-wave velocity layer, interpreted as saturated zone. The utilized geophysical methods successfully characterized the different materials of the embankment and identified zones of potential seepage. [ABSTRACT FROM AUTHOR]

This study goes on the enhancement of thermal performance of a chimney type electrically heated hot storage tanks (HST) in static mode. The different natural circulation areas (chimney areas) were used with different diameter of large (9.5 cm), medium (2.5 cm) and small (1.5 cm) to find the effect of natural circulation on HST performance. Being part of real system, the performance of chimney insulated and without chimney insulation was also studied. The experiments showed that the chimney significantly affects the thermal stratification within the tank. Different chimney contact diameters (9.5 cm, 2.5 cm and 1.5 cm) were tested giving varying degrees of thermal stratification. It was found that the smaller chimney contact diameters led to higher thermal stratification that gives a more rapid heating of the top layer temperatures. The impact of insulation on thermal performance was inconclusive as top layer temperatures of the tank were still rising, showing the need of a more effective insulation as well as further investigation into the dynamic mode of operation. It is also noted that the top outer layer had the higher rate of temperature rising to the larger diameter, giving the sign of the importance of the chimney type electrical heater in the hot storage tank. [ABSTRACT FROM AUTHOR]

The operation of fuel-burning heating equipment results in soot build-up in the flues. Its ignition poses a significant fire risk to the building, as the flue temperature can reach 1000°C. Wooden structural elements located near the chimney (ceilings and roof penetrations) are particularly vulnerable. To date, research has focused on the fire safety of wooden ceiling elements. This is where, due to heat radiation from the chimney, wooden elements significantly increase their temperature and become the location of fire initiation in the buildings. The task of chimney designers is to limit the temperatures of heated wooden building components near these structures. The present work analysed a ceramic and concrete chimney with air space with an innovative perlite concrete casing with a dual-function (load-bearing and thermal insulation). Computational Fluid Dynamics (CFD) analyses verified by a full-scale experiment were conducted to evaluate the fire safety of wooden building ceilings. The tests showed that a high level of safety characterised the chimney under study. The maximum temperature of the casing when testing the soot fire reached 38°C, and the wooden elements simulating the ceiling reached 28°C - this result is almost four times better than the chimney standard requirement. Furthermore, a developed CFD model exhibited high accuracy compared to the experimental results and can be used for designing this type of chimney and other research and expert work, such as that performed after fires in buildings originating from the chimney. Practical Application: The article describes CFD analyses and tests of an innovative chimney in a perlite-concrete casing. The described research showed the high safety of such a chimney during soot fires. The results obtained can be used to develop changes in standards to improve the safety of chimneys and design safer and more efficient ones. The author's chimney model and CFD analysis make it possible to determine the temperatures in the chimney during a soot fire. This CFD model allows you to assess the fire safety of the chimney and the building elements located in its vicinity. [ABSTRACT FROM AUTHOR]

Copyright of Revista del Museo de Antropología is the property of Museo de Antropologia - IDACOR and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Open in new tab Download slide OBJECTIVES After staged reconstruction for hypoplastic left heart syndrome, the neoaortic root tends to dilate, and the incidence of significant neoaortic valve insufficiency increases with time. This study aimed to evaluate the mid-term outcomes of the neoaortic root geometries and valve function after chimney reconstruction in the Norwood procedure. METHODS Between 2013 and 2021, 20 consecutive patients who underwent chimney reconstruction during the Norwood procedure for hypoplastic left heart syndrome and its variants in our institution were enrolled. The actual diameters of the following points were measured, and Z-scores were calculated based on the normal aortic root geometries using the long axis view of echocardiography at the pre-Norwood stage and the lateral view of angiography at pre-Glenn, pre-Fontan, post-Fontan and follow-up (age 5–6 years) stages: neoaortic valve annulus; sinus of Valsalva; sinotubular junction; and ascending aorta just proximal to the anastomosis to the aortic arch. The degree of neoaortic valve regurgitation was evaluated by echocardiography at each stage. RESULTS The median follow-up period was 3.9 years. Neoaortic roots after chimney reconstruction were spared from progressive dilation over time. With growth, the conical configuration of the neoaortic roots was preserved without geometrical distortion. The Z-scores of the annulus, sinus of Valsalva, sinotubular junction and ascending aorta ranged roughly from 4 to 6, 4 to 6, 2 to 4 and 0 to 2, respectively. All neoaortic valves at each stage had mild or no regurgitation. CONCLUSIONS Chimney reconstruction prevented neoaortic root dilation and avoided significant neoaortic valve regurgitation in the mid-term. These neoaortic dimensions with smooth flow profiles in the neoaorta after chimney reconstruction may have contributed to the current results. Further studies are needed to clarify the long-term outcomes. [ABSTRACT FROM AUTHOR]

Understanding the impact of anthropogenic threats, such as light pollution, on biodiversity is necessary to establish effective guidelines to protect diminishing wildlife. In this study, we examined the effect of artificial light at night (ALAN) on the roosting behaviour of Chimney Swifts Chaetura pelagica, a highly threatened migratory bird species that lives commensally with humans, where it often breeds and roosts in artificial structures such as chimneys. Although Chimney Swifts are known to use time of sunset in combination with temperature, wind and season to coordinate roost entry, we predicted that high ALAN exposure would override these natural cues and lead to a delayed entry compared with sites with less light pollution. To test this, we examined the effects of ALAN on the start and end times of entry to 21 roosting sites located along a light pollution gradient in New Jersey and the New York Metropolitan area. We found that ALAN was a significant predictor of roosting entry time, with birds entering later in sites with more light pollution. While Chimney Swifts initiated roosting earlier in the summer months compared with the autumn, this effect was absent in areas with high light pollution. These findings highlight the need to determine the causes and consequences of light pollution effects. [ABSTRACT FROM AUTHOR]

We examined the changes in the ocean’s upper layer structure involved in the formation of the subtropical mode water in the South Atlantic. Here we present the results from a survey done in the region of formation between 37°W and 32°W and 34°S and 37°S from July–October 2018, using high-resolution measurements obtained from an underwater glider. From its records, the mode water development was observed for the first time in the South Atlantic as localized chimney-like patterns in the temperature, salinity, and potential vorticity (PV) measurements with a horizontal scale of (7 ± 2) km, associated with wintertime oceanic convective processes. Over time, these submesoscale structures tend to expand and dominate the region as a large volume of mode water. These vertical structures present highly homogeneous temperature and salinity values. The observed PV was on the order of 5.0 × 10−11 m−1 s−1, which is one order of magnitude smaller than the pre-existent mode water at the lower layers; negative values were observed, indicating active convection. A 1-D vertical model was used to predict the depth of the mixed layer conditioned by the surface fluxes and triggered by its changes in winter to late spring. Comparisons of the sea surface temperature measured from satellite collocated with the glider’s measurements showed a very good agreement. From this analysis, we were able to establish the decorrelation scales that characterize mode water formation. Further inspection of the glider data yielded temporal decorrelation scales indicative of convection modified by planetary rotation. [ABSTRACT FROM AUTHOR]

Tropical cyclones (TCs) induce heat pump and cold suction in the upper ocean layer. However, limited research investigated whether this heat can be effectively transported into the deep ocean. The present study shows that seawater at Station S2 is anomalously warmer in the deep ocean layer than at S1 and S3 during Typhoon Kalmaegi (2014) in the South China Sea. The turbulence‐induced vertical heat flux is estimated based on fine‐scale mixing parameterization but it cannot explain the warming rate below the thermocline. Therefore, a new method is proposed to estimate the vertical velocity, allowing us to calculate the heat flux more accurately. To elucidate the underlying causes of the observed differences, we analyze horizontal velocity to examine the role of mesoscale eddies in modulating near‐inertial waves (NIWs)‐induced vertical heat flux. Station S1 is located inside a cyclonic eddy while S2 and S3 are within two distinct anticyclonic eddies. According to the “Chimney Effect” theory, cyclonic (anticyclonic) eddies tend to limit (enhance) the vertical propagation of the NIWs. While this theory explains the confined heat flux at S1, it fails to explain the differences observed at S2 and S3. Further examination of the vertical structures and intensities of the two anticyclonic eddies reveals that the eddy at S2 extends much deeper and is stronger than that at S3, allowing the NIWs to propagate and transport heat deeper at S2 than at S3. The study demonstrates the role of TC‐induced NIWs in deep ocean heat transport under the influence of mesoscale eddies. [ABSTRACT FROM AUTHOR]

Solar energy is one of the most feasible options to produce energy in countries where unexploited desert areas or solar radiation are abundant. An energy tower is an effective system for electrical power generation that can perform more efficiently along with solar radiation. As the primary aim of the present study, effects of different environmental parameters on total efficacy of energy tower were investigated. In this study, the efficiency of the energy tower system is investigated experimentally by an indoor fully adjustable apparatus. In this regard, a comprehensive set of influencing parameters like air velocity, humidity, and temperature and the effects of tower height on the performance of the energy tower are individually assessed. It is demonstrated that there is a direct relationship between an increase in humidity percentage of the surrounding and performance of energy tower, meaning that a 274% increase in humidification rate led to 43% elevation in airflow velocity. The kinetic energy increases in the direction of airflow from top to bottom, and as the height of the tower lengthens, the kinetic energy enhances and subsequently increases the overall efficiency of the tower. An elevation about 2.7% in airflow velocity was seen due to an increase from 180 to 250 cm in chimney height. Although the energy tower performs efficiently in the nighttime, airflow velocity increases averagely about 8% during the daytime and at the peak of the solar radiation, the airflow velocity enhances by 58% compared to nighttime. [ABSTRACT FROM AUTHOR]