Bottom Section Research Articles

Effect Of Young Coconut Water Concentration On Bud Chip Germination Phase On Several Parts Of SugarCane (Saccharum Officinarum L.) Stems

The germination phase of sugarcane is a pivotal stage crucial for successful cultivation. Seeds derived from six to eight-month-old gardens, obtained from protrusions of sugarcane stems, are employed. These seeds exhibit characteristics of dormant buds, contributing to their suitability for germination. A single sugarcane stem typically harbors a minimum of 13 buds, and the selection of seeds with 2-8 eyes per spike is customary among farmers. However, excessive bud usage may lead to abnormal seed growth, underscoring the importance of careful selection. The study employs the rase cage test system, dividing the sugarcane stem into upper, middle, and bottom sections to determine the optimal bud quantity in each treatment. The research investigates the response of different parts of sugarcane bud chip stems to varying concentrations of coconut water growth regulator during germination. Utilizing a factorial randomized block design, the study comprises two factors: Bud chip (BA: Upper Stem, BT: Middle Stem, BB: Bottom Stem) and coconut water growth regulator concentration (Z1: 25%, Z2: 50%, Z3: 75%, Z4: 100%). Positive control involves Agrogibb at a concentration of 120 ppm, with all treatments soaked for six hours. Conducted at the Indonesian Sugar Plantation Research Center on January 10, 2023, the study reveals that the BBZ1 treatment significantly affects the observed parameter of shoot emergence, with an average of 8.1 days. Conversely, the BAZ1 treatment exhibits the fastest and most efficient shoot emergence, with an average of 5.1 days, outperforming other treatments. These findings underscore the importance of careful selection and treatment in the germination phase for optimal sugarcane productivity.

Characterization of the properties of Buluh Madu (Gigantochloa albociliata)

Thirteen bamboo species are reported to be in commercial use in Malaysia. However, Buluh madu (Gigantochloa albociliata) did not make to the list. As a species, G. albociliata is cultivated for its delicious bamboo shoot and is demonstrated to possess great potential to produce commercialised products such as laminated bamboo panel. Unlike common bamboo, which has hollow cylindrical culms, G. albociliata has thick culms at the base, with smaller hollow cavities at the top portion. Therefore, it can be easily converted into high-thickness strips, thus improving the processing efficiency of laminated bamboo. To validate this theory, the anatomical, chemical, physical, and mechanical properties of G. albociliata were evaluated. The round bamboo and strips from the top and bottom sections of the bamboo stem were tested. It was found that G. albociliata has a vascular bundle type similar to that of the Gigantochloa genus bamboo. The fibre in G. albociliata is long and strong. The top section of bamboo has longer fibres, a higher density, and a higher specific gravity than the bottom section. As a result, bamboo from the top section has greater bending strength than bamboo from the bottom section. The G. albociliata species was discovered to have high mechanical strength, dimensional stability, and good wettability, making it an ideal material for laminated products.

The Tissue Browning and Concomitant Toughening of Yellow Flammulina filiformis Stipes Is Caused by Oxidative Damage-Mediated Metabolic Disorder and Cell Wall Glycan Remodeling.

The browning and associated toughening of fruiting body stipes are the main causes of declines in the commercial production of yellow Flammulina filiformis. The dynamic metabolic changes from the top to bottom stipe sections of yellow F. filiformis fruiting bodies were investigated by integrating physiological, transcriptomic, and metabolomic analyses. The results indicated that oxidative stress levels gradually increased accompanying the degree of tissue browning and toughening from the top to bottom sections of F. filiformis stipes. In-depth analysis showed that there were remarkable changes in the expression of genes, and the content of metabolites correlated with the primary and secondary metabolism of F. filiformis stipes. Interestingly, the expression levels of genes participating in chitosan biosynthesis and the degree of deacetylation of chitosan increased from top to bottom in F. filiformis stipes, implying that cell wall glycan remodeling may contribute to concomitant toughening of the browning of F. filiformis stipes.

Micro-flow structure at regime transition from bubbling to turbulent fluidization in a fluidized bed

Gas-solid fluidized beds have found extensive utilization in frontline manufacturing, in particular as low-velocity beds. The fluidization status, the bubbling or turbulent flow regime and the transition in between, determine the system performance in practical applications. Though the convoluted hydrodynamics are quantitively evaluated through numerous data-processing methodologies, none of them alone can reflect all the critical information to identify the transition from the bubbling to the turbulent regime. Accordingly, this study was to exploit a coupling data processing methodology, in the combination of standard deviation, power spectrum density, probability density function, wavelet transform, and wavelet multiresolution method, to jointly explain the micro-flow structure at the regime transition from bubbling to turbulent fluidization. The transient differential pressure fluctuation was measured for the evaluation in a fluidized bed (0.267 m i.d. × 2.5 m height) with FCC catalysts (d¯p=65μm, ρp=1780kg/m3) at different superficial gas velocities (0.02–1.4 m/s). The results show that the onset of turbulent fluidization starts earlier in the top section of the bed than in the bottom section. The wavelet decomposition displays that the fluctuation of differential pressure mainly concentrates on the sub-signals with an intermediate frequency band. These sub-signals could be synthesized into three types of scales (micro-scale, meso-scale, and macro-scale), representing the multi-scale hydrodynamics in the fluidized bed. The micro-scale signal has the characteristic information of bubbling fluidization, and the characteristic information of turbulent fluidization is mainly represented by the meso-scale signal. This work provides a systematic comprehension of fluidization status assessment and serves as an impetus for more coupling analysis in this sector.

Numerical study of aeration flow angle on powder flow and thermal behaviors in fluidized bed particle solar receivers

The particle flow and thermal characteristics in fluidized bed particle solar receivers with different aeration flow angles were numerically investigated by employing the Eulerian-Eulerian two-fluid model. The filtered drag correlation was utilized to characterize the interaction between SiC particles of Geldart-A classification and gas. The model underwent validation using experimental data from the literature, confirming that the simulated solid holdup and local heat transfer rate agreed well with the experimental measurements. Simulation results show that the particle volume fraction was higher along the walls in the bottom section. In both +45° and + 60°, the particles returned to the aeration flow region. The aeration had a relatively small impact on the particle distribution at the center, whereas the other two regions (x / D = 0.5 and 0.95) exhibited a significant decrease in particle volume fraction at the height of aeration injection. For different aeration injection structures, the equilibrium temperature rise reached approximately 51% of the difference between the wall and inlet temperatures. The temperature rise of particles in FBPSR was attributed to the direct heat transfer from the heating wall to particles and he return of hot particles.

A parametric study and experimental investigations of microstructure and mechanical properties of multi-layered structure of metal core wire using wire arc additive manufacturing

In the present study, the Gas metal arc welding (GMAW) based Wire-arc additive manufacturing (WAAM) process was preferred for the fabrication of multi-layered structures and their investigations of mechanical properties on metal core wire. Based on literature work, preliminary trials, machine limits, travel speed (TS), voltage (V), and gas mixture ratio (GMR) were identified as machining parameters along with output factors of bead width (BW), bead height (BH), and depth-of-penetration (DOP). Experiments were conducted by following the Box-Behnken design. The feasibility of the generated non-linear regression models has been validated through the statistical analysis of variance and residual plots. The multi-layered structure has been successfully fabricated at the optimized parametric settings of TS at 24 mm/s; the voltage at 24 V, and GMR at 1 which was obtained through the heat transfer search (HTS) algorithm. The fabricated structure was observed to be uniform. The structure exhibited uniform bead-on-bead deposition for the deposited layers. The fabricated multi-layered structure underwent a detailed microstructural and mechanical examinations. Microstructural examination revealed dense needles at the bottom section of the structure as compared to the top section, as the bottom section undergoes multiple heating and cooling cycles. When comparing the multilayer structure to the metal core wire, all the properties exhibited favorable tensile characteristics. The obtained strength from the impact test results highlights the impressive ductility of the multi-layer deposition. Fractography of tensile and impact test specimens has shown the occurrences of larger dimples and suggested a ductile fracture. Lastly, the hardness value in all the sections of the built structure was observed to be uniform, suggesting uniform deposition across the built multi-layer structure. The authors consider the current work will be highly beneficial for users in fabricating multi-layer structures at optimized parametric settings and their investigations for mechanical properties for metal core wire.

Experimental Study on Dynamic Barite Sag and Effects of Inclination and Pipe Rotation

Summary Barite sag causes pressure fluctuations in the wellbore, which is undesirable. These problems usually occur with oil-based muds (OBMs; invert emulsion muds) and are associated with fluid properties and operation parameters. Drilling issues related to this undesirable phenomenon include wellbore instability, lost circulation, and stuck pipes. As barite sagging is a complex phenomenon, the mechanisms that cause and aggravate it still need to be fully understood to mitigate these problems. This study examines barite sagging in the wellbore with inner pipe rotation to understand the process and develop prevention strategies. Thus, a flow loop study with OBM is conducted in a concentric annular test section with varying inner pipe rotation and inclination angles. The tests were performed at an elevated temperature (49°C) to simulate borehole conditions. By measuring the pressure profile in a mud sample trapped in the test section, barite sagging was evaluated. Using the data, we calculated the density difference between the top and bottom sections of the column. The novelty of the work lies in continuous monitoring of the density profile of the mud column, which is sheared between two coaxial cylinders to simulate drillstring rotation in the wellbore, and utilizing the data for evaluating barite sag. The results show the evolution of the pressure profile with time, indicating the sagging of barite particles at the bottom of the test section. Due to barite sagging, the density of the top portion of the mud column decreased over time, while the density of the bottom part increased. The lateral sedimentation of barite particles toward the annulus outer wall enhances barite sag in inclined configurations. The sedimentation creates two suspension layers with different densities, leading to secondary flow, which enhances sagging. Hence, the primary factor driving barite sagging is inclination. An increase in inclination angle from 0° to 50° resulted in a significant (more than twofold) increase in mud density difference. Also, the rotation of the pipe delayed sagging during the early phases of the testing process (less than 20 minutes). However, it did not have much effect as the sagging progressed, resulting in approximately the same density difference in both cases (i.e., with and without rotation).

The gradient high entropy alloy coating prepared in-situ by bidirectional diffusion of Mo/Nb and FeCoCrNi

Based on the influence of Mo and Nb content on the eutectic degree of FeCoCrNi high-entropy alloy (HEA), this study prepared in-situ HEA composite coatings with a gradient eutectic degree using the principle of element diffusion in the molten pool under a laser beam, namely Mo-CC and Nb-CC. Both of the two coatings were composed of the face-centered cubic (FCC) phase and Laves phase. Within the coating, there was a gradual decrease in the Laves phase and an increase in the FCC phase from top to bottom. The Laves phase in Mo-CC was rich in Mo (21.36 at.%) element and exhibited an orientation relationship with the FCC phase of [01¯1]Laves//[01¯1]FCC. The phase interface was a non-coherent crystal plane. The Laves phase in Nb-CC is enriched with Nb (36.15 at.%) element and demonstrated an orientation relationship with the FCC phase of [1¯2¯1]Laves//[001]FCC. The phase interface was a semi-coherent crystal plane. Furthermore, the process and mechanism of FCC phase transformation into FCC + Laves phase were elucidated by examining the mixing enthalpy, lattice distortion, and atomic radius difference. In terms of properties, the hardness of Mo-CC and Nb-CC from the top to the bottom section gradually decreased from the outer to inner section. Nb-CC possessed a higher surface average hardness (773.66 HV0.3) and superior tribological properties compared to Mo-CC. The gradient control method for HEA and the phase structure formation mechanism presented in this study provided valuable insights for the research and development of new HEA coatings.

Statement of Removal

ABSTRACTStrengthening the thermal response of Phase-Change Materials (PCMs) is an essential and active field of research with promising potential for advanced applications such as solar energy storage, building energy conservation, and thermal management in electronic devices. This article evaluates the efficacy of a new arc-shaped fin array in shell-and-tube heat storage systems to enhance the PCM response during the discharge mode. Different fin geometric parameters including the fin curvature angle, the fin spacing, and the nonuniform angle between fins in the top and bottom sections of the PCM domain were considered to identify the best-performing layout. The analysis shows that increasing the curvature of arc-shaped fins between 60° and 180° and increasing the fin spacing between 5 and 15 mm can significantly reduce solidifying time and improve heat recovery rates. Moreover, the arc-shaped fins are more efficient than conventional longitudinal (+-shaped) fins, which are commonly employed in thermal energy storage applications. Arc-shaped fins can also save discharge time by more than half and improve the rate of heat recovery by almost four times than that of + -shaped fins. The present findings suggest that arc-shaped fins represent a promising design for enhancing the heat-recovery aspects in PCM-based energy storage systems.

Vertical distributions of organic matter components in sea ice near Cambridge Bay, Dease Strait, Canadian Archipelago

Ice algae thriving within sea ice play a crucial role in transferring energy to higher trophic levels and influencing biogeochemical processes in polar oceans; however, the distribution of organic matter within the ice interior is not well understood. This study aimed to investigate the vertical distribution of organic matter, including chlorophyll a (Chl-a), particulate organic carbon and nitrogen (POC and PON), carbohydrates (CHO), proteins (PRT), lipids (LIP), and food material (FM), within the sea ice. Samples were collected from the bottom, middle, and top sections of the sea ice column near Cambridge Bay during the spring of 2018. Based on the δ13C signature, biochemical composition, and POC contribution of biopolymeric carbon (BPC), the organic substances within the sea ice were predominantly attributed to marine autotrophs. While the highest concentrations of each parameter were observed at the sea ice bottom, notable concentrations were also found in the upper sections. The average sea ice column-integrated Chl-a concentration was 5.05 ± 2.26 mg m−2, with the bottom ice section contributing 59% (S.D. = ± 10%) to the total integration. The column-integrated concentrations of FM, BPC, POC, and PON were 2.05 ± 0.39, 1.10 ± 0.20, 1.47 ± 0.25, and 0.09 ± 0.03 g m−2, respectively. Contributions of the bottom ice section to these column-integrated concentrations varied for each parameter, with values of 20 ± 6, 21 ± 7, 19 ± 5, and 28 ± 7%, respectively. While the bottom ice section exhibited a substantial Chl-a contribution in line with previous studies, significantly higher contributions of the other parameters were observed in the upper sea ice sections. This suggests that the particulate matter within the interior of the sea ice could potentially serve as an additional food source for higher trophic grazers or act as a seeding material for a phytoplankton bloom during the ice melting season. Our findings highlight the importance of comprehensive field measurements encompassing the entire sea ice section to better understand the distribution of organic carbon pools within the sea ice in the Arctic Ocean.

Effect of softening duration on physical, mechanical and microstructural properties of flattened densified Bambusa bambos

The half-split Bambusa bambos culms were flattened after subjecting them to different steaming durations in the range of 20–40 min. The flattened bamboos from bottom, middle and top sections were further subjected to the densification process using a hot press. Various physical and mechanical properties of the flattened and densified bamboo (FDB) were evaluated and compared with control. Analytical techniques such as scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were applied to study the microstructure and chemical changes due to flattening and densification. The results showed that softening duration had significant effect on all the properties of the FDB. The flattened sheets prepared from the bottom, middle and top portions of bamboo showed different properties. The density of the FDB was observed to increase significantly compared to untreated bamboo. The significant density improvements lead to relatively uniform distribution of the vascular bundles through the radial direction of the culm wall. Although the water absorption of the FDB boards was significantly reduced compared to control, no improvement was observed in the dimensional stability after water submersion for 24 h. With the increase in softening duration, various mechanical properties such as flexural strength, flexural stiffness and tensile strength parallel to fibre direction of FDB were improved significantly. The SEM observations showed that the microstructure of parenchyma and vessel elements changed significantly while fibre microstructure was undisturbed. FTIR analysis showed that hemicellulose content was slightly reduced while other chemical constituents of bamboo were not much affected. The crystallinity of the bamboo was found to be increased after flattening and densification leading to improvement in strength properties. These findings may be of practical importance for efficient utilization of bamboo in production of value-added FDB composites.

Experimental and numerical investigation of the mechanical behavior of a cable-stayed bridge with shell-shaped pylons

A novel cable-stayed bridge (CSB) with shell-shaped pylons was first proposed, of which the shell-shaped pylons were uniquely composed of five concrete-filled steel tube (CFST) pylon arches (PAs) and curved circular hollow steel transverse braces. To investigate the force transmission mechanism of this new type of CSB, a static loading test of a 1:25 scale model of the whole bridge and finite element analysis (FEA) of the prototype bridge were performed. The results showed that under the action of vehicular load the shell-shaped pylon and main girder jointly shared the load effect in a distribution ratio of 1:9, and the stress levels of the pylon arch in the middle (PAm) and the pylon arch immediately next to it (PAn) were much greater than the outermost pylon arch (PAo), and the maximum stress occurred at the bottom section of PAs. However, the location where the maximum stress occurred under permanent load would shift to the junction section of the curve and the straight segment of the PAs. Meanwhile, the stress levels of PAm, PAn, and PAo were almost equal under the temperature load, and the maximum stress occurred at the apex of the arch. Furthermore, the refined FEA results of the steel–concrete composite pylon pedestal showed that there were obvious stress concentrations at the steel tubular intersecting joints of the PAm and PAn and the connection area between the connecting steel plate and the steel tube in the pylon pedestal. Nevertheless, the pylon pedestal still behaved elastically under the ultimate limit state.

Railway Bridge Geometry Assessment Supported by Cutting-Edge Reality Capture Technologies and 3D As-Designed Models

Documentation of structural visual inspections is necessary for its monitoring, maintenance, and decision about its rehabilitation, and structural strengthening. In recent times, close-range photogrammetry (CRP) based on unmanned aerial vehicles (UAVs) and terrestrial laser scanners (TLS) have greatly improved the survey phase. These technologies can be used independently or in combination to provide a 3D as-is image-based model of the railway bridge. In this study, TLS captured the side and bottom sections of the deck, while the CRP-based UAV captured the side and top sections of the deck, and the track. The combination of post-processing techniques enabled the merging of TLS and CRP models, resulting in the creation of an accurate 3D representation of the complete railway bridge deck. Additionally, a 3D as-designed model was developed based on the design plans of the bridge. The as-designed model is compared to the as-is model through a 3D digital registration. The comparison allows the detection of dimensional deviation and surface alignments. The results reveal slight deviations in the structural dimension with a global average value of 9 mm.

Experimental study of precast concrete walls with replaceable corner components

AbstractTo improve the seismic resiliency of precast concrete (PC) wall, a type of emulative PC wall with replaceable corner components (RCCs) was developed in this study. The damage of the PC wall was deliberately concentrated in the RCCs, which can be replaced after an earthquake. Four large‐aspect‐ratio specimens (including three PC walls with different tensile strength RCCs, and one monolithic cast‐in‐place reinforced concrete (RC) wall) were tested to investigate the seismic behavior of the PC wall, the replaceability of the RCCs, and comparability of the PC wall with the RC wall. Although flexural failure occurred for the three PC walls, the locations of damage were different. For PC walls with low and moderate tensile strength RCCs, the damage was successfully concentrated in RCCs, while for PC wall with high tensile strength RCCs, the damage was expanded from RCCs to the non‐replaced part of the PC wall. When RCCs had approximately identical tensile strength to the boundary element of RC wall, the performance of the PC wall emulated that of the RC wall. The ultimate drift ratio of the PC walls ranged from 1.7% to 2.2% which is lower than that of 2.7% for the RC wall. The PC wall, before and after replacing RCCs, exhibited approximately identical lateral load, while slight lower initial stiffness. The vertical displacement profiles of wall bottom section were almost linear, and the yielding and peak strength of the PC walls could be reasonably estimated by assuming the wall bottom section remain plane after deformation.

Analysis of mechanical and anatomical properties of two bamboo species – Thyrostachys siamensis Gamble and Dendrocalamus strictus (Roxb.) Nees (Poaceae)

Bamboos are treated to boost their shelf life from the degrading activity of fungal microbes and other insects and to increase their longevity in use and durability by using various chemicals. The present study is vis-a-vis the standardization of two bamboo species Dendrocalamus strictus and Thyrostachys siamensis for a comparative analysis of the mechanical and anatomical properties of samples treated with CCB (Copper Chrome Boron), and BBA (Borax Boric Acid) as well as untreated samples.Samples were tested for both bending and compression; and the parameters such as MOE (Modulus of Elasticity), MOI (Moment of Inertia), Maximum compressive strength, and ultimate strength were analyzed. The anatomical variations arising in the top and bottom sections were also investigated and it has found that the mechanical properties of the species treated with CCB solutions yield a better result in maximum compressive strength and high value of MOI as compared to BBA whereas the samples treated with BBA provides superior performance with respect to MOE. Anatomical examination revealed that the cellular structure and arrangement of vascular bundles are responsible for the increase in time taken for the rate of penetration of chemicals in D.strictus i.e one-half hour as compared to T.siamensis which got treated in 20 minutes. In D.strictus the density of vascular bundles is high so it takes time to get it treated completely as compared to T. siamensis.

Novel Bottom-Side Polished PCF-Based Plasmonic Biosensor for Early Detection of Hazardous Cancerous Cells.

This work presents a single-core bowl-shaped bottom-side polished (BSP) photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) concept for the early detection of hazardous cancer cells in human blood, skin, cervical, breast, and adrenal glands. We have studied liquid samples of cancer-affected and healthy samples with their concentrations/refractive indices in the sensing medium. To induce a plasmonic effect in the PCF sensor, the bottom flat section of a silica PCF fiber is coated with a 40nm plasmonic material, such as gold. To strengthen this effect, a thin TiO2 layer of 5 nm is sandwiched between fiber and gold as it strongly holds gold nanoparticles with smooth fiber surface. When the cancer-affected sample is introduced to the sensor's sensing medium, it produces a different absorption peak in the form of a resonance wavelength than the healthy sample. This reallocation of the absorption peak is used to determine sensitivity. Hence, the obtained sensitivities for blood cancer, cervical cancer, adrenal gland cancer, skin cancer, and breast cancer (type-1and type-2) cells are 22,857nm/RIU, 20000nm/RIU, 20714nm/RIU, 20000nm/RIU, 21428nm/RIU, and 25000nm/RIU, respectively, with highest detection limit 0.024. These strong findings indicate that our proposed cancer sensor PCF is a viable choice for early cancer cell detection.

A Wideband Rotary-Joint-Free H-Plane Horn Antenna With 360° Steerable Radiation Pattern Using Gap Waveguide Technology

Considering the limitations of electronically steerable antennas such as limited steering span, gain degradation for large steering angles, complexity, and cost, this paper is focused on the design of a simple mechanically steerable H-plane horn antenna. It is shown that since there is no need for an electrical connection between the top and bottom sections of a gap waveguide, if a sectoral horn is properly designed and realized using this technology, the pattern of the antenna can be easily steered without a rotary joint. To demonstrate this concept, a rotary-joint-free H-plane horn antenna is designed, and its performance is predicted using EM simulations. The antenna offers a wide operating band covering almost the entire Ku band and provides a full 360-degree continuous steering span. Additionally, the proposed antenna benefits from a constant gain over the full range of steering angles. This is in contrast to phased array antennas whose gain degrades when the main beam is steered away from the broadside. The proposed concept and computed characteristics are verified by good agreement between the simulated and measured characteristics of the fabricated prototype.

Longitudinal and Radial Variability of Anatomical Properties, Fiber Morphology, and Mechanical Properties of Fibrovascular Bundle from Indonesian Arenga Longipes Mogea. Sp. Nov Frond

ABSTRACT This study aimed to characterize the physical, anatomical, fiber morphology, as well as mechanical properties of fibrovascular bundle (FVB) from Arenga longipes fronds, based on radial and longitudinal direction. In this research, the fronds were divided into three parts in longitudinal direction (bottom, middle, and upper) sections, three parts in radial direction (outer-convex and concave, as well as middle and inner) zones. The FVB’s anatomical and fiber morphology were observed by light microscope, as well as mechanical properties were tested using the universal testing machine (UTM). The results showed that the longitudinal direction variability had different properties physically particularly in relation to the FVB diameter and density, anatomically in terms of the ratio of vascular tissue area (VTA) to total transverse area (TTA), as well as in the fiber morphology and mechanical properties. Radially, the outer position had a higher value variability of diameter, density, and mechanical properties, compared to the middle and inner zones, respectively. Furthermore, there were relationships between the density and mechanical properties as well as the ratio of VTA to TTA and mechanical properties. Based on the results, the FVB of A. longipes fronds was concluded to possess properties variability in the radial and longitudinal direction.

Study on the Performance of Polyurea Anti-Seepage Spray Coating for Hydraulic Structures

The surfaces of hydraulic structures are vulnerable to damage and cracking, which can result in high-pressure reservoir water entering cracks and endangering the safety of the structures. Therefore, it is necessary to strengthen the anti-seepage treatment and protection on the surfaces of the structures. In this paper, we explore the tensile and high-water-pressure breakdown resistance properties of polyurea coating material. To do so, we independently designed and manufactured a high-water-pressure breakdown test device for coating. Our experimental results indicated that the thickness of the polyurea coating decreased with an increase in elongation. Furthermore, we found that the breakdown resistance of the polyurea coating was related to the coating thickness and the bottom free section width. We then fitted the stress–strain curve obtained from the experimental test using the Ogden constitutive model. Based on this, we numerically simulated the high-water-pressure breakdown performance of the polyurea coating using the finite element software ABAQUS 2022. We obtained the relationships among maximum displacement, free section width, and coating thickness under high water pressure. Our numerical findings indicated that the vertical displacement of the midpoint increased linearly with width in the case of the same coating thickness under water pressure load. Conversely, for the same free section width, the vertical displacement decreased with increasing coating thickness.

The Influence of Storage Tank Volume on the Nighttime Heat Dissipation and Freezing Process of All-Glass Vacuum Tube Solar Water Heaters

The issue of freezing often occurs when using all-glass vacuum tube solar water heaters during cold winter seasons, leading to problems such as pipe ruptures and tank leakage. In order to further study the nocturnal heat dissipation and freezing characteristics of these heaters, a three-dimensional transient numerical model of their nocturnal heat dissipation was established. The model simulated the nocturnal heat dissipation process, and experimental validations were conducted through nocturnal temperature drops of the collector and temperature drops of individual tubes without a storage tank. Experimental and simulation results revealed that in clear weather conditions during cold winters in Luoyang, the all-glass vacuum tube solar water heaters experienced freezing issues during the night, with freezing predominantly starting from the bottom surface of the vacuum tubes. The frozen length along the tube wall and the thickness of ice at the bottom section reached up to 1180 mm and 5 mm, respectively. In the absence of a storage tank, the freezing situation was severe, with approximately 4/5 of the individual tubes completely frozen. Under specified operating conditions, different storage tank volumes exhibited varying degrees of freezing in the all-glass vacuum tube solar water heaters. When the volume was increased to 15 L, the temperature drop in the storage tank and the vacuum tubes decreased by 12.1% and 7.6%, respectively. Larger storage tank volumes resulted in reduced freezing risks in all-glass vacuum tube solar collectors. This study provides valuable guidance for the design and application of solar collectors and serves as a reference for the development and application of solar energy utilization technologies.