Thick Lines Research Articles

Detection method of icing thickness of overhead transmission lines based on canny algorithm

Detection method of icing thickness of overhead transmission lines based on canny algorithm

Influence on energy demand of thickness, thermal conductivity, and volumetric heat capacity of ladle working lining in secondary steel-making process

The secondary steel-making process involves several steps during which steel is kept in a ladle, that is, a vessel made of an outer steel layer (carpentry), an intermediate refractory layer, and an internal refractory layer. Unlike the intermediate layer, the internal layer undergoes a progressive reduction in thickness and a periodic restoration. Traditionally, it is made of alumina or magnesite. During the process, the ladle undergoes unsteady heating and cooling; therefore, heat transfer depends on thermal conductivity and heat capacity. This study aims to identify the ladle internal layer characteristics that affect the energy demand. This analysis investigates the effect of the internal layer thickness S, volumetric heat capacity C, and thermal conductivity λ. Through the Design Of the Experiments (DOE), different scenarios have been selected and analyzed by means of numerical simulations performed on a numerical model defined in COMSOL Multiphysics. The energy demand as a function of the internal layer properties has been estimated, and it has emerged that low thermal conductivity and heat capacity values require a lower amount of energy.

Towards an active semi-anechoic room: simulations and first measurements

Semi-anechoic rooms are used for the acoustic characterisation of noise sources. They involve heavy infrastructures and thick absorbent lining. The aim of this work is to demonstrate a less expensive alternative by complementing a thin passive coating with an active technology. Previous work has achieved the active reduction of the pressure scattered by the reflective wall of a semi-anechoic room, in the 80–200 Hz frequency band. This work validated an innovative approach allowing to control the scattered pressure throughout the measurement volume, using a setup located over its periphery. This paper extends a previous presentation at Forum Acusticum dealing with the active control of the low-frequency reflections on the walls and ceiling of a semi-anechoic room [Pinhède et al., Forum Acusticum 2023, Torino, Italy, 11–15 September, 2023, https://doi.org/10.61782/fa.2023.0399]. We describe the design principles and the 2D semi-analytical and 3D finite element simulations of the control system that help optimise parameters such as the transducers number and locations. A full-scale demonstrator has been built to validate the control strategy. Acoustics measurements, which have been used to characterise the room acoustics and to update the simulation parameters are also presented and compared to an updated numerical model.

Analyzing the early impact dynamics of single droplets impacting onto wetted surfaces

Single droplet impacts onto thin wall-films are a common phenomenon in many applications. For sufficiently high impact velocities, the droplet impact process consists of three phases, i.e., initial contact stage, droplet deformation with radial momentum transfer inducing an upward rising lamella, and crown propagation. Here, we present the results of a combined numerical and experimental study focusing on the early dynamics of the impact process. Specifically, the effects of the initial droplet shape, wall-film thickness, and contact line motion are analyzed. Prior to impact, an oblate spheroidal droplet shape was observed. Using direct numerical simulation, we show that the droplet shape affects the impact dynamics only during the first two phases, as it is one of the key parameter influencing the correct prediction of the impact zone. The contact line propagation is described by a square-root-time dependence R¯CL=ατ for both, dry and wetted surfaces. On dry surfaces, the advancement of the contact line is determined by the rolling motion of the truncated droplet. On wetted surfaces, the value of the α-parameter is controlled by two concurrent effects, namely, rolling motion and wall-film inertia. For impact onto thin films, the rolling motion prevails. With increasing wall-film height, the droplet penetrates into the soft substrates and wall-film inertia becomes the controlling factor. These insights into the early impact dynamics on wetted surface are important for the formulation of a unified modeling approach.

Problem rozliczenia z komunistyczną przeszłością u progu zmiany systemowej w Polsce

The process of settling accounts with the communist past is an answer to the question for countries that are leaving communism through peaceful negotiations with the authorities. In the case of the Polish control system, the first non-communist introduction by Tadeusz Mazowiecki, which is used as the socalled ‘thick line’, it leaked that the problem of lustration and decommunization had been postponed. In the subsequent years of the 1990s, verification tests among people performing the most important functions ended in failure. The most serious consequences occurred in the attempt to implement the lustration resolution by the Sejm in May 1992, which resulted from the failure of Jan Olszewski’s actions. The first lustration act was issued in Poland only in 1997.

<i>Telipogon pillaropatatensis</i> (Oncidiinae): a new species from the East-Central Andes of Ecuador

A new species, Telipogon pillaropatatensis, is described from the highlands of east-central Ecuador. It is morphologically similar to T. octavioi but differs by having a corolla with longitudinal thick vein lines without reticulations and a column with three dense bundles of equally sized setae. Also, our phylogenetic analyses suggest that they are not closely related. Interestingly, among the analyzed taxa, T. pillaropatatensis appears to have a closer phylogenetic relationship with the highly distinct T. pulcher and T. hausmannianus than with the morphologically similar T. octavioi. The new species has been found in a relatively small area, covering just a few square kilometers in east-central Ecuador. Additionally, we documented remarkable variation in the coloration and size of the corolla. Information regarding the species' habitat, ecology, phylogenetic relationships, and conservation status is also provided.

The investigation of printing parameters effect on tensile characteristics for triply periodic minimal surface designs by Taguchi

AbstractThe advent of additive manufacturing also referred to as 3D printing, has brought about substantial changes in the industrial domain, as it possesses the capability to fabricate intricate items with enhanced cost‐efficiency and productivity. Fused Filament Fabrication (FFF) is a 3D printing process that has gained significant popularity due to its versatile capabilities and cost‐effectiveness. This paper investigates the impact of the printing parameters on the tensile characteristics of Triply Periodic Minimal Surface (TPMS) manufactured using FFF 3D printing. TPMS patterns have unique geometric properties and potential applications, making them an intriguing subject of study. The behavior of three different TPMS lattices with three printing parameters is investigated. Finding the best testing settings is done with the Taguchi method, and the data is analyzed with the Analysis of Variance (ANOVA) test. TPMS pattern was found to be the most effective parameter with 83.78%. While the highest strength was obtained in Schwarz diamond, the highest energy absorption was observed in the Gyroid structure. The contributions of printing parameters to tensile strength are line thickness, printing speed, and layer height, respectively. As line width and printing speed increase, both energy absorption and strength increase. Therefore, 0.40 mm line width and 60 mm/s printing speed give optimum values. When considered for energy absorption, the optimum value is 0.20 mm layer height, while when considered for strength, 0.10 mm layer height is the optimum value. The findings emphasize the importance of optimizing printing parameters for desired mechanical characteristics in 3D printed components and highlight the potential of TPMS structures in various applications. This research contributes to the growing knowledge in additive manufacturing and provides insights into optimizing FFF 3D printing for improved mechanical performance.

Beam displacement tolerances on a segmented mirror for higher-order Hermite–Gauss modes

Odd-indexed higher-order Hermite–Gauss (HG) modes are compatible with four-quadrant segmented mirrors due to their intensity nulls along the principal axes, which guarantees minimum beam intensity illuminating the bond lines between the segments thus leading to low power loss. However, a misplaced HG beam can cause extra power loss due to the bright intensity spots probing the bond lines. This paper analytically and numerically studies the beam displacement tolerances on a segmented mirror for the mode. We conclude that for ‘effective’ bond lines with 6 µm width, and the beam size chosen to guarantee 1 ppm clipping loss when centered, the beam can be rotated by roughly 1∘ or laterally displaced by 4% of its beam size while keeping the total power on the bond lines under 1 ppm. We also demonstrate that the constrained beam displacement parameter region that guarantees a given power loss limit, or the beam displacement tolerance, is inversely proportional to the bond line thickness.

Performance of Single-Layer Lining Using Shotcrete and Reinforcement Ribs Employed for Supporting Large-Span Tunnel.

Single-layer tunnel lining using shotcrete has the significant advantages of reducing the tunnel excavation volume and saving construction materials, which has been gradually applied in tunnel construction. The high-performance concretes are generally adopted in single-layer tunnel lining for enhancing the bearing capacity of the tunnel lining, whereas the single-layer tunnel lining may still induce damages due to the adverse conditions such as shallow buried depth of the tunnel, and further study related to its application condition is thus required. This paper presents a study of the single-layer tunnel lining with shotcrete employed for supporting the large-span tunnel, in which the reinforcement ribs are also adopted in the single-layer lining for improving the lining stiffness and strength. The study is implemented using numerical simulation, focusing on the safety and performance variation of the single-layer tunnel lining influenced from the varied lining thicknesses and shallow buried depths of the tunnel. The results shows that the single-layer tunnel lining has the obvious advantage of toughness in significantly absorbing large deformation of surrounding rocks and improving the ability to resist lining cracking. The results also demonstrate that the single-layer tunnel lining with shotcrete and reinforcement ribs can safely support the large-span tunnel, in which the stability and safety of the large-span tunnel are confirmed from both the tunnel deformation and lining stresses. Moreover, the factors related to both the lining thickness and shallow buried depth of the tunnel have great influence on the single-layer tunnel lining with shotcrete and reinforcement ribs, in which the insufficient lining thickness and excessive shallow buried depth of the tunnel can induce the damages of the single-layer tunnel lining due to shotcrete stresses exceeding its strength. This study provides some references of employing the single-layer tunnel lining with shotcrete and reinforcement ribs for supporting large-span tunnel.

Feasibility of Bonding High-Moisture-Content Wood Using Nothofagus chilean Species

Appraising and protecting forests requires a management plan and the creation of innovative products for the market. The development of the green gluing technique could add value to native timber. However, there is a lack of knowledge concerning the response and the productive process of Nothofagus species using this technique. This work investigated the viability of implementing the green gluing method using three types of Nothofagus. Wood pieces were made using a one-component polyurethane adhesive. Delamination, shear tests, morphological characterization, and bond line thickness analysis tested their capacity. The results showed a variable response depending on the Nothofagus type, where the surface treatment could improve the green gluing performance. The findings highlight the relevance of increasing knowledge about the essayed species and their preparation to maintain their natural moisture condition.

Identification of Qualitative and Quantitative Characteristics of Male Bali Cattle in Dompu District

Livestock identification is a form of recording that must be done to provide information about individual livestock. This study aimed to identify the qualitative and quantitative characteristics of male bali cattle in Dompu Regency. Data analysis was carried out using statistics descriptive, using the average, standard deviation, and coefficient of variation. One hundred twenty male bali cattle aged 1-36 months were used as samples. The results showed the frequency of each feature was 47.5% light brown fur color, 32.5% dark brown, and 20% black. The eel line was 40% thick line, 15% medium line, 25% thin line, and 20% did not have eel line. The metatarsal color was 87.5% white with a firm border and 12.5% white with an indistinct border. The rump color was 82.5% white with a firm boundary and 17.5% white with an indistinct boundary. The tail feather color was 37.5% black-brown, 32.5% brown, and 30% black. Furthermore, the measurement results obtained for quantitative properties were 113.8 ± 10.0 for body length, with a 8.8% coefficient of variation. Chest circumference were 147.2 ± 11.8, with a 8.0% coefficient of variation. Back height were 112.0 ± 7.9, with a 7.1% coefficient of variation. Hip height were 115.8 ± 8.4, with a 7.2% coefficient of variation. Body weight were 287.6 ± 40.1, with a 14.0% coefficient of variation. The study results show that the male bali cattle characteristics at Dompu Regency are relatively heterogenous, both qualitatively and quantitatively.

Modeling of Stainless Steel Bending Force on CNC Press Brake

Bending processing is one of the most common plastic deformation processing procedures. It is widely represented in the metal processing industry. In this paper, sheet metal bending on a CNC press with a tool that has two basic parts is analysed: the lower-die and the upper-punch. The sheet metal material is stainless steel, which is one of the most commonly used materials. During the bending process on presses, one of the main challenges is the experimental determination of the bending force. The methodology used in this work is based on the experimental stochastic method, that is, design of experiment. A rotatable plan for three input parameters: material thickness, bending angle and bending line length, are varied at five levels. The output parameter is precisely the bending force. No special devices are needed to measure the bending force as an output parameter, because the bending force is measured and registered on the CNC press via the control panel. After the experiment, using the experimental design matrix, the coefficients of an adequate nonlinear mathematical model were determined. Such a mathematical model is suitable for analysis and optimization of the bending force.

Application of Ground Penetrating Radar and High Density Seismic Mapping Method in Tunnel Concrete Lining Detection

If there are quality defects such as voids, non-compactness, insufficient lining thickness, and water-filled voids in the concrete structure, the bearing capacity and durability of the tunnel concrete lining structure will inevitably be affected. The non-destructive testing of tunnel concrete is a problem that the engineering community generally pays attention to, and it is the key to ensure the safe operation of tunnel concrete structures. Combined with engineering examples, the principle and method of using ground penetrating radar method and high-density seismic imaging method to detect internal defects of concrete are expounded, and the process of data processing is briefly introduced. The results are consistent, indicating the accuracy and feasibility of the ground penetrating radar method combined with the high-density seismic imaging method to detect the internal defects of tunnel concrete.

New Resonance Scattering Model in AtomDB: Application to Line Suppression in Galaxy Clusters and Elliptical Galaxies

In this paper, we present the simple, one-step, self-consistent, and fast resonance scattering model rsapec based on the AtomDB database. This model can be used as an alternative to the commonly used APEC model for fitting X-ray spectra with optically thick lines. The current model is intended, in general, for verifying the presence of the effect and for spectral modeling of galaxy clusters and elliptical galaxies under applicable assumptions. We test rsapec to derive the line suppression in the elliptical galaxy NGC 4636 and the Perseus cluster of galaxies and obtain resonance suppressions of ∼1.24 and ∼1.30, respectively.

Dry-Contact Thermal Interface Material with the Desired Bond Line Thickness and Ultralow Applied Thermal Resistance.

Efforts to directly utilize thixotropic polymer composites for out-of-plane thermal transport applications, known as thermal interface materials (TIMs), have been impeded by their mediocre applied thermal resistance (Reff) in a sandwiched structure. Different from traditional attempts at enhancing thermal conductivity, this study proposes a low-bond line thickness (BLT) path for mitigating the sandwiched thermal impedance. Taking the most common TIM, polydimethylsiloxane/aluminum oxide/zinc oxide (PDMS/Al2O3/ZnO), as an example, liquid metal is designed to on-demand localize at the Al2O3-polymer and Al2O3-filler interface regions, breaking rheological challenges for lowering the BLT. Specifically, during the sandwiched compression process, interfacial LM is just like the lubricant, dexterously promoting the relaxation of immobilized PDMS chains and helping fillers to flow through mitigating the internal friction between Al2O3 and adjacent filler. As a result, this TIM first time exhibits a boundary BLT (4.28 μm) that almost approaches the diameter of the maximum filler and performs an ultralow dry-contact Reff of 4.05 mm2 K/W at 40 psi, outperforming most reported and commercial dry-contact TIMs. This study of the low-BLT direction is believed to point to a new path for future research on high-performance TIMs.

Flexible and elastic thermal regulator for multimode intelligent temperature control

AbstractAs nonlinear thermal devices, thermal regulators can intelligently respond to temperature and control heat flow through changes in heat transfer capacities, which allows them to reduce energy consumption without external intervention. However, current thermal regulators generally based on high‐quality crystalline‐structure transitions are intrinsically rigid, which may cause structural damage and functional failure under mechanical strain; moreover, they are difficult to integrate into emerging soft electronic platforms. In this study, we develop a flexible, elastic thermal regulator based on the reversible thermally induced deformation of a liquid crystal elastomer/liquid metal (LCE/LM) composite foam. By adjusting the crosslinking densities, the LCE foam exhibits a high actuation strain of 121% with flexibility below the nematic–isotropic phase transition temperature (TNI) and hyperelasticity above TNI. The incorporation of LM results in a high thermal resistance switching ratio of 3.8 over a wide working temperature window of 60°C with good cycling stability. This feature originates from the synergistic effect of fragmentation and recombination of the internal LM network and lengthening and shortening of the bond line thickness. Furthermore, we fabricate a “grid window” utilizing photic‐thermal integrated thermal control, achieving a superior heat supply of 13.7°C at a light intensity of 180 mW/cm2 and a thermal protection of 43.4°C at 1200 mW/cm2. The proposed method meets the mechanical softness requirements of thermal regulator materials with multimode intelligent temperature control.

Automatic recognition of defects behind railway tunnel linings in GPR images using transfer learning

Ground-penetrating radar (GPR) is widely used for non-destructive detection of hidden defects behind railway tunnel linings, including non-compactness, air- and water-filled voids, fractures, and insufficient lining thickness. However, manual interpreting a substantial volume of GPR B-scan images is time-consuming, and the results heavily depend on the professional knowledge of the practitioner and the available prior information. This paper presents an automatic recognition algorithm for detecting hidden defects, as well as estimating lining thickness in GPR B-scan images of railway tunnels using a You Only Look Once for Panoptic driving perception network (YOLOP) model. The process mainly contains three steps. Firstly, a real GPR dataset of underground objects is employed for transfer learning to enhance the robustness of the prediction model. Secondly, a dataset containing 2,245 real GPR B-scan images of railway tunnel linings is created. Thirdly, the established dataset is used to retrain the YOLOP model and assess the prediction accuracy for identifying hidden defects and lining thickness in GPR images. Field experiment results demonstrate that the trained hidden defects recognition algorithm achieves an average accuracy of 80.6%, with a detection time of only 0.02 s for a GPR image sizing of 1024 × 512. Therefore, it is concluded that the proposed algorithm is efficient and reliable for automatic recognition of hidden defects behind railway tunnel linings.

Influence of the margin design on the fracture resistance of implant supported monolithic zirconia crowns: An “In Vitro” Study

Introduction: The purpose of this in vitro study was to test the influence of the margin design of implant supported monolithic zirconia crowns and test if monolithic zirconia crowns with extra fine finish line thickness cemented on zirconia implant abutments can bare the maximum masticatory forces on molars and hence be used in the posterior region. Methods: Fourteen identical monolithic zirconia crowns cemented on zirconia implant abutments mounted on titanium bases and fixed on implant replicas embedded in PMMA resin were divided into two groups: group I designed with a 0.5 mm CFL (CFL) and group II with a feather-edge finish line (FEFL) of 0.3 mm. All specimens underwent static load until fracture in order to determine the break force. Break forces in N were recorded for each group. Results: The CFL group exhibited slightly higher fracture resistance (1879.14 ± 322.28 N) compared to the feather-edge finish line group (1685.00 ± 362.18 N). However, statistical analysis revealed that the observed difference between the two groups (194.14 ± 183.24; p = 0.310) was not significant. Conclusions: Within the limitations of this study, both monolithic zirconia crowns with 0.5 mm chamfer and 0.3 mm feather edge margins cemented on zirconia implant abutments can be used in the posterior region as their resistance to fracture is similar and surpasses the maximum masticatory force applied on molars.

A Theoretical Study on the Spatiotemporal Variation in the Temperature Field in Linings of High-Water-Temperature Tunnels.

On the basis of the theory of unsteady heat conduction, discrete equations for the unsteady temperature field in the secondary linings of high-water-temperature tunnels when considering the hydration heat of lining concrete were derived and established. Spatiotemporal variation in the temperature field of tunnel linings was revealed through the analysis of numerical examples. Research demonstrates that the temperature of the secondary lining within a thickness range of approximately 15 cm near the tunnel clearance decreases sharply under the condition that the lining thickness is 35 cm. The higher the temperature on the lining's outer surface, the more drastically the lining temperature decreases. When considering the hydration heat of lining concrete, the lining temperature increases to a certain extent after a sudden drop, reaching stability after approximately 20 h, and the lining temperature is approximately 1-2 °C higher than that without taking concrete hydration heat into account. The temperature difference between the tunnel lining's core and its inner and outer surfaces is positively and negatively correlated with the temperature of the secondary lining's outer surface, respectively. When the temperature of the secondary lining's outer surface is not higher than 65 °C, the temperature difference between the tunnel lining's core and its inner and outer surfaces is less than 20 °C. Conversely, it partially or completely exceeds 20 °C, in which case an insulation method is recommended to utilize to prevent thermal cracks in secondary linings triggered via a high temperature difference.

Prediction of bearing capacity of cracked asymmetrical double-arch tunnels using the artificial neural networks

Cracking in lining structures has the potential to seriously weaken the lining's carrying capacity. In this paper, the failure performance of cracked lining was firstly obtained by model tests and numerical simulations. An artificial neural network model was subsequently developed using extensive simulation data derived from the verified numerical model, to forecast the capacity loss in cracked double-arch tunnels. The results showed that: (1) The cracks caused the linings to undergo localized crushing failure, which greatly reduced the double-arch tunnels' load-bearing capacity. The cracked linings entered a stable working stage with cracks initially and then progressed directly to the destabilization stage, displaying hidden and sudden characteristics; (2) The neural network model, developed using a large number of numerical simulations, demonstrated outstanding predictive performance and accurately forecasted the load-bearing capacity of double-arch tunnels; (3) The depth of the cracks was the principal factor influencing the load carrying capacity decrease in double-arch tunnels, particularly in the vicinity of the void; (4) The structural capacity diminished swiftly when crack depth surpasses 30% of the lining's thickness, and larger voids and cracks closer to the voids amplified the lining-bearing capacity loss for equivalent crack depths.