Straight Walls Research Articles

Microanatomy sectioning and phytochemicals overview in selected Oleaceae species

This study provides in-depth observations into the microanatomical structure of leaves and stem of eight selected Oleaceae species revealing comprehensive tissue organization using microtome sectioning and peeling leaf epidermis techniques. The phytochemicals profile overview of selected olive species extracted from leaf and stem of Oleaceae species contributes to identifying bioactive compounds with potential therapeutic and medicinal applications. An overview of histochemistry of bioactive metabolites revealed in Oleacee species shows the presence of phenolic compounds (oleuropein and hydroxytyrosol), localized in the leaves and stems, contributing to their antioxidant properties. The present study represent foliar anatomical traits; epidermal cells (ECs) polygonal shape and straight anticlinal walls, paracytic stomata and simple unicellular trichomes. The maximum ECs length (30 μm) was noted in Olea europaea and minimum (20 μm) in Jasminum fluminense was measured. Oleaceae species microtome stem sectioning examined revealed cortex type (parenchyma and collenchyma), vascular bundles (VBs) arrangements (radial, scattered and bundled), xylem vessels (scalariform, annular, spiral and reticulate), phloem fiber arrangements (banded and scattered), and uniseriate, biseriat and multiseriate medullary rays. Stem transverse section with maximum length (1300 μm) was observed in Olea europaea and the lowest (1100 μm) in Jasminum grandiflorum L. subsp. floribundum. This taxonomic histological method links the relationship between anatomy and chemistry, lead to identification of bioactive chemical compounds diversity among Oleaceae species. This anatomical methods used to enhance and consider the plant micromorphological structure-function relationships adapted to diverse environmental conditions.

Model test study on the dynamic failure process of tunnel surrounding rocks in jointed rock mass under explosive load

The presence of joints can significantly reduce the integrity and stability of an engineering rock mass. Under dynamic loads, such as from blasting excavation, the key blocks divided by joints may be destabilized and prone to sliding, potentially leading to engineering geological disasters like rockbursts. To study the dynamic instability process, similar materials for the rock mass and joints were developed based on the similarity theory, and a tunnel model in the jointed rock mass was constructed. Subsequently, a detonating fuse was used to generate a dynamic load, and the dynamic instability process of the tunnel surrounding rock in the jointed rock mass under explosive load was studied using the geotechnical multifunctional testing device. The deformation characteristics and dynamic instability process of the tunnel surrounding rock were analyzed using acceleration sensors, resistance strain gages, linear variable displacement transducers and motion camera. The study shows that the acceleration at the tunnel vault is significantly greater than at the straight wall and floor under blast loads, with differences reaching an order of magnitude. Acceleration waveforms were classified into three categories based on peak characteristics, explained through the propagation of explosive stress waves. Additionally, strain and displacement at the tunnel arch were also significantly greater than in other areas, indicating more severe stress concentration and dynamic damage at the arch, necessitating reinforced support in tunnel excavation. The entire dynamic instability process of the tunnel surrounding rock was successfully recorded using a motion camera. The dynamic failure process was divided into several phases, the appearance of cracks on the joint surface, particle ejection accompanied by the dropping of jointed blocks, a significant drop of the jointed blocks, and return to calm. The dynamic failure modes include the dropping and rotation of jointed blocks, local particle ejection, and shear cracks on jointed block.

PID Controller with an Override Mode for a Wall-Following Robot with a Rotating Sensor Compartment

This paper presents the design of a wall-following robot (WFR) with a rotating sensor compartment to reduce the number of distance sensors used. Two infrared (IR) sensors were fitted in the compartment that rotates back and forth at 45°, producing four measurement values at each rotation cycle. The WFR was regulated using a novel control scheme of PID controller with an override mode. A discrete PID controller in position form was used to run the WFR to follow straight wall segments or walls turning left, while an override mode governed the WFR to follow walls turning right. The sampling time was set to 300 ms. The parameters of the PID controller were tuned using a trial-and-error method. The Mean Absolute Errors (MAE) was selected as the cost function. The WFR conducted twelve trial runs along a trial track with a length of 200 cm, consisting of one right turn and one left turn. The parameters that yielded the lowest MAE of 0.90 cm were used for further tests. Subsequently, a closed track for testing was constructed with a length of 845 cm, consisting of 7 right turns and 2 left turns. The WFR completed five test runs successfully, each elapsing the test track twice. The lowest MAE during the tests was 1.06 cm. The favorable performance of the proposed WFR strengthens future development efforts to equip the robot with more hardware to fulfill specific tasks and to put the completion time into optimization consideration.

Reliable comparison of multi-directional mechanical properties for biomimetic circle arc honeycombs

Abstract Compared to straight honeycombs, curved honeycombs derived from biomimetic strategies typically exhibit superior mechanical properties and a broader tunable range. Consequently, there has been a surge in research focusing on curved honeycombs. However, few studies have concurrently designed multiple honeycombs for reliable comparisons, and little attention has been given to isotropy. In this study, circle arc walls were introduced to replace the straight walls of five classical honeycombs, thereby creating representative curved honeycombs for analysis. The numerical modeling method in ANSYS software was validated by experimentally testing 3D printed specimens of circle arc honeycombs. At the same mass and under loading conditions in different directions, it was found that the Young's modulus, yield strength, Poisson's ratio, and energy absorption of circle arc hexagon (CAH), circle arc square (CAS), circle arc triangle (CAT), circle arc re-entrant (CAR), and circle arc double-V (CAD) were assessed. Both experimental and numerical results revealed that CAH demonstrates superior energy absorption while maintaining a high degree of isotropy, characterized by all isotropic factors below 0.1 in mechanical properties. Notably, CAD exhibits a Negative Poisson's ratio (NPR) effect across all loading directions. These results provide benchmarks for future studies on curved honeycombs and guide further research in this field.

Generation of nonlinear gravity waves based on the harmonic polynomial cell method incorporated with a mass source

A nonlinear numerical wave tank is established using the Harmonic Polynomial Cell (HPC) method, which is incorporated with a mass source. The numerical wave tank consists of the mass source wave generation region and the working region, with sponge layers at both ends for wave absorption. In the mass source region, a generalized HPC method is applied to solve the inhomogeneous elliptic boundary value problems. The Poisson equation's special solution is represented by a bi-quadratic function. In the remaining domains, the HPC method is employed with harmonic polynomials to solve the problems governed by the Laplace equation in each grid cell. The free surface is tackled by the immersed boundary method (IB-HPC), and the kinematic and dynamic conditions of the free surface are described using a semi-Lagrangian approach. A variety of waves propagation are simulated, including Second-order Stokes wave, fifth-order Stokes wave, solitary wave, fifth-order Fenton stream function wave, random wave and the interaction with a straight vertical wall. The numerical solutions are compared with theoretical solutions. The numerical simulation results demonstrate that the present method can generate arbitrary two-dimensional wave fields by specifying an appropriate source function. Additionally, the reflected waves can propagate through the wave generation region, ensuring that the process of wave generation is not affected by the reflections.

Investigation of the Traveling Performance of the Tracked Chassis of a Potato Combine Harvester in Hilly and Mountainous Areas

Aiming at the problems of poor passability of a tracked chassis due to small plots, complicated road conditions and steep slopes during mechanized potato harvesting in hilly and mountainous areas. To design a potato combine harvester and take the tracked chassis of the harvester as the research object to study its driving performance under typical road conditions in mountainous areas. Firstly, mechanical analysis and theoretical calculation are carried out on the tracked chassis to obtain the relevant parameters of key components, and secondly, its driving performance is analyzed to obtain the driving limit values of passing performance under different working conditions; RecurDyn software was used to establish the dynamics simulation and analysis model of the whole machine, and the driving limit values of the harvester were determined under five different road conditions through simulation. The results show the following: the driving limit gradient angle is 20° in cross-gradient conditions, 25° in longitudinal up-gradient conditions, 25° in longitudinal down-gradient conditions, the limiting height of the chassis that can be overpassed in obstacle-crossing conditions is 450 mm, and the limiting width of the chassis that can be spanned in trench-crossing conditions is 1200 mm. The simulation results were verified through field tests, and the results of the field tests showed that the harvester met the requirements of stable travelling on longitudinal slopes of 24°, climbed over a 450 mm straight wall and crossed over a 1200 mm trench, which were similar to the simulation results, indicating that the simulation results were accurate and feasible, and met the design requirements for the travelling passage of the crawler potato harvester. This study provides an in-depth understanding of the tracked chassis of the potato combine harvester in hilly mountainous areas, with a view to providing reference for the design of tracked harvesters for other crops in hilly mountainous areas.

A molecular ferroelectric thin film of imidazolium perchlorate on silicon

Molecular ferroelectrics have garnered significant attention due to their structural tunability, low synthesis temperature, and high flexibility. Herein, we successfully synthesized imidazole perchlorate (ImClO4) single crystals and high-quality, highly-oriented thin films on Si substrates. These films demonstrated a high inverse piezoelectric coefficient of 55.7 pm/V. Two types of domain bands were observed: type-I bands tilted ~60° relative to the horizontal axis, and type-II bands positioned perpendicular to the horizontal axis. Under a + 20 V bias, type-I bands showed a reduction and detachment of 180° domain walls to form a needle-like domain. It extended toward the band boundary after applying −20 V bias, which grew along the boundary upon contact. In contrast, type-II bands showed straight domain wall motion and displayed a higher piezoresponse than type-I bands. The growth of high quality molecular ferroelectric thin films on Si substrates paves the way for the development of on-chip devices.

A Electron micrograph of the leaf epidermal structure of legumes

Our goal was to find morphological features that can help us identify or describe the stomata ontogeny and epidermal structures. Our team got seeds of two types of leguminous plants—Arachis hypogaea L. groundnuts and Vigna subterranean L. bambaranuts—from the Kano State Agricultural and Rural Development Authority and the Yankaba market in Nassarawa, which is in Kano State. The study specifically evaluated the leaf epidermal studies, stomata development (ontogeny), types of stomata, stomata size, pore length, pore width, and stomata index in both the surfaces of the leaves. We conducted ontogenetic studies using safety razor blades on the epidermal layers. We determined the stomata index by studying the type of stomata, the number of stomata, and the number of epidermal cells. We subjected the obtained data to a one-way analysis of variance. All the studied varieties/species exhibited amphistomatic stomata on both surfaces, with a higher density on the lower surface. In SAMNUT 23, we found the paracytic type of stomata, which is perigynous and has an irregular anticlinal cell wall. In Dandakar, we found the tetracyclic type, which is mesogynous and has a pentagonal epidermal cell shape and a slightly straight anticlinal cell wall. Finally, in Bambara nuts, we found the endocytic type, which is polygonal with a curved anticlinal wall and a mesoperigynous ontogeny.

On determining residual stresses in a viscoelastic coating of arbitrary thickness formed during multilayer application on the inner surface of the straight pipe wall

Abstract The technological problem of forming a coating of arbitrary thickness on the inner surface of the wall of a straight pipe due to the multilayer application of a material having the property of viscoelasticity is considered. It is assumed that during the forming process, the coating experiences the action of inertia forces due to the relatively intense rotation of the coated wall. To determine the residual stresses in the resulting coating, a non-classical model of deformable solid mechanics, based on the concepts of growing continuum is used. With the help of the developed model, boundary value problems are formulated, the solutions of which make it possible to construct the desired residual stress distributions for arbitrary programs for changing the parameters of the implemented technological process.

Numerical experimental study on combined support of bolt-arch in circular roadway

The deep soft rock roadway is in high stress environment, and the surrounding rock is prone to large deformation. Appropriate roadway cross-section form and high-strength support are effective control methods for surrounding rock deformation. Circular roadway is widely used in mine engineering because of its uniform stress and deformation, which gives full play to the characteristics of rock compression and non-tension. With the advantages of high strength, high cost performance and stability, the application of arch frame in deep soft rock roadway is increasing day by day. Based on this, based on the engineering background of deep roadway in extremely soft rock in sea area, numerical experiments were carried out using the FLAC3D bolt-arch fine numerical simulation platform. The progressive failure characteristics of bolt-arch combined support in soft rock roadway are revealed. The influence law of roadway section form, geostress grade and lateral pressure coefficient on support effect is clarified. The results show that: (1) Under the condition of deep soft rock, the surrounding rock deformation of circular roadway is uniform. Compared with the straight wall semi-circular roadway, the deformation is reduced by about 86% at most. (2) The failure of arch frame in circular roadway has a significant influence on the final control effect of surrounding rock. When the ground stress exceeds 15 MPa, the loss of bearing capacity of arch frame is instantaneous, and the deformation of surrounding rock increases suddenly. (3) When the support of circular roadway in deep soft rock fails, the axial force of bolt is very small, and it basically does not play a supporting role. According to the research results, the support optimization design is carried out, and the field verification is obtained.

Morpho-anatomical studies of family lamiaceae species of district Lahore, Punjab: a revision to flora of Pakistan

BackgroundThis study was aimed to determine the taxonomic position and delimitation of fifteen Lamiaceae taxa using leaf epidermal morpho-anatomical features in Lahore. A main objective of the study was also the revision and upgradation of Lamiaceae taxa in the flora of Pakistan, as no details of studied species are found in the flora of Pakistan.MethodsThe examination of significant anatomical parameters, such as epidermal cell shape and size, stomatal types, guard and subsidiary cells shape and size, stomatal cavity size, trichome size and shape, oil droplets, crystals, and secretory cavity characteristics were studied using light microscopic (LM) and scanning electron microscopic (SEM) techniques. Among all the studied Lamiaceae species, these anatomical features varied significantly. Principal component analysis and correlation were done to distinguish the species’ similarities.ResultsMost species had pentagonal and hexagonal epidermal cells with straight anticlinal wall thickness. On the adaxial surface, paracytic stomata were found in Ocimum basilicum L. and Rosmarinus officinalis L. Diacytic stomata was observed in Ajuga reptans L. and anisocytic stomata in Galeopsis tetrahit L. In the abaxial surface, trichomes were present in five species, i.e., Mentha suaveolens Ehrh. A. reptans, Thymus vulgaris L., M. haplocalyx, and Salvia splendens Ewat. In S. splendens, peltate and glandular trichomes were seen whereas, in other species, trichomes were long, unbranched glandular and had tapering ends. In adaxial side trichomes were present only in M. suaveolens, A. reptans, S. bazyntina, O. basciculum, S. splendens, S. officinalis, S. rosemarinus. In other species, trichomes were absent on the adaxial surface. In abaxial view, M. suaveolens had the largest length of trichomes, and O. basciculum had the smallest. S. splendens L. had the largest trichome width, while T. vulgaris had the smallest.ConclusionHence, according to these findings, morpho-anatomical traits are useful for identifying Lamiaceae taxa. Also, there is a need of upgradation and addition of studied taxa in flora of Pakistan comprehensively.

Research on the Protection Scheme of a High-Speed Railway Crossing 1000 KV Ultra-High Voltage Transmission Line

The high-speed railway project and the ultra-high-voltage transmission project represent two crucial components of China’s “new infrastructure”. As the construction of these two projects progresses rapidly, it is inevitable that instances of intersections will occur. Extreme conditions may cause damage to ultra-high voltage transmission cables. When a high-speed train passes by an ultra-high voltage transmission line, it poses a serious safety hazard. To address this issue, engineering examples were utilized to examine the protection structure scheme, protection distance, protection load, and construction procedures when a high-speed railway intersects a 1000 KV ultra-high voltage transmission line. A shed structure form and construction method for the electric power protection were proposed to ensure the safe operation of the high-speed railway while also achieving the safe and rapid construction of the high-speed railway protection structure in the safety zone of the approaching 1000 kV ultra-high voltage transmission line. The results indicated that the protection of high-speed railway crossings and 1000 kV ultra-high voltage transmission lines primarily focuses on line-break protection. The concrete shed structure with a straight wall and a flat roof was designed to meet the requirements of high-speed railway crossings. The line-break protection method enables the construction of an automatic warning protection corridor and a complete movable trolley quickly and safely within the safety zone near the transmission line. The implementation effect is, therefore, positive. It can be used as a reference point for other projects of a similar nature.

Geometric factors affecting CO2 separation in a supersonic separator

The current work evaluates a potential carbon separation approach with swirl flows and spontaneous condensation. Euler-Euler model is established to depict the spontaneous condensation. By combining Euler-Lagrange model and Euler-Euler model, the droplet motion behavior is predicted, and the influence of separator structure including swirl generator and gap length on the separation efficiency of CO2 is quantified. The flue gas expands under pressure to create a non-equilibrium system, which leads to the emergence of CO2 condensation nuclei. On the surface of nuclei, metastable molecules aggregate and promote the growth of CO2 droplets. Based on the force on droplets, the droplet behavior can be separated into three categories: impacting the straight tube wall, entering the collector and entering the diffuser. When the angle of swirl generator and gap length rises by 315° and 3.75 mm respectively, the separation efficiency rises by 60.3 % and 48.6 %, respectively.

Study on the safe distance of spatial intersecting tunnel cavern under ground shock

The vertical distance of intersection area is an important factor dominating the service performance of spatial intersecting cavern. To obtain the influence of vertical distance on the dynamic response of orthogonal spatial intersecting caverns under ground shock, the plastic region and peak particle velocity (PPV) distribution are investigated by numerical simulation. A finite-dynamic model is established to simulate the mechanical response of the deeply bureid structure subjected to coupled static and dynamic load, with an artifical boundary condition setting method. The results indicate that as the vertical distance decreases, the plastic region in the intersection area gradually merges, while the bolt support at the lower cavern vault effectively suppresses the destruction of the intersection area. The free surface of the lower cavern vault weakens the bottom support conditions of the upper cavern floor structure, resulting in higher PPV when vertical distance is smaller. Conversely, as vertical distance increases, isolation effect of upper cavern on ground shock weakens, leading to an increase and followed by a decrease in PPV at the lower cavern vault and straight wall. Morever, when vertical distance exceeds than 3 times the cavern characteristic size, the lower cavern exhibits dynamic response characteristics of deeply buried single-cavern. when vertical distance within 3 times, there is significant interaction between caverns with inverse relationship between dynamic axial stress on bolts in intersection area and PPV at lower cavern vault. It is recommended to use comprehensive criteria involving PPV and plastic region distribution to evaluate safety performance for spatial intersecting cavern.

Water Dams: From Ancient to Present Times and into the Future

Since ancient times, dams have been built to store water, control rivers, and irrigate agricultural land to meet human needs. By the end of the 19th century, hydroelectric power stations arose and extended the purposes of dams. Today, dams can be seen as part of the renewable energy supply infrastructure. The word dam comes from French and is defined in dictionaries using words like strange, dike, and obstacle. In other words, a dam is a structure that stores water and directs it to the desired location, with a dam being built in front of river valleys. Dams built on rivers serve various purposes such as the supply of drinking water, agricultural irrigation, flood control, the supply of industrial water, power generation, recreation, the movement control of solids, and fisheries. Dams can also be built in a catchment area to capture and store the rainwater in arid and semi-arid areas. Dams can be built from concrete or natural materials such as earth and rock. There are various types of dams: embankment dams (earth-fill dams, rock-fill dams, and rock-fill dams with concrete faces) and rigid dams (gravity dams, rolled compacted concrete dams, arch dams, and buttress dams). A gravity dam is a straight wall of stone masonry or earthen material that can withstand the full force of the water pressure. In other words, the pressure of the water transfers the vertical compressive forces and horizontal shear forces to the foundations beneath the dam. The strength of a gravity dam ultimately depends on its weight and the strength of its foundations. Most dams built in ancient times were constructed as gravity dams. An arch dam, on the other hand, has a convex curved surface that faces the water. The forces generated by the water pressure are transferred to the sides of the structure by horizontal lines. The horizontal, normal, and shear forces resist the weight at the edges. When viewed in a horizontal section, an arch dam has a curved shape. This type of dam can also resist water pressure due to its particular shape that allows the transfer of the forces generated by the stored water to the rock foundations. This article takes a detailed look at hydraulic engineering in dams over the millennia. Lessons should be learned from the successful and unsuccessful applications and operations of dams. Water resource managers, policymakers, and stakeholders can use these lessons to achieve sustainable development goals in times of climate change and water crisis.

Evaluation of Home Product Quality Using the Importance-Performance Analysis Method at PT. Galaxy Alam Semesta

Government support for the property sector through incentive policies, such as the Ministry of Finance Regulation on Government-Borne Value Added Tax (VAT-GOV) on properties, was reintroduced in 2024 to boost economic growth, focusing on the delivery of new landed houses and new apartment units. In this context, property and real estate companies are required to maintain customer satisfaction, which is the key to the company's success. Customer satisfaction not only reflects product quality but also influences the company's brand image. To understand customer satisfaction with product quality, particularly landed houses, PT. Galaxy Alam Semesta conducts periodic surveys of its customers. However, survey results from the first semester of 2023 indicated that customer satisfaction with the quality of houses was still below the company's standards. Therefore, this research aims to evaluate the quality of PT. Galaxy Alam Semesta's houses using the Importance-Performance Analysis method. This research will identify attributes that need quality improvement priority, with the hope of enhancing customer satisfaction and the company's image, as well as utilizing the House of Quality to determine the priority of these improvement proposals. The analysis results indicate that the attributes requiring quality improvement priority are even and non-streaky paint, straight wall corners, even wall and ceiling surfaces, smoothly and easily operable doors and windows, neat and even paint and sealant, even tile installation, and precise and neat installation of door and window accessories. From the analysis of the proposed improvement, five main priorities were identified: increasing the frequency of supervision and inspection to ensure compliance with quality standards, setting limits on the number of units overseen by building supervisors, using higher quality paint, evaluating the quality of door accessories and tile materials, and conducting regular evaluations and selections of contractors.

Micromorphological study of some Salsola species (Amaranthaceae) in Iran and its systematic significance using scanning electron microscopy.

Using scanning electron microscopy (SEM), six Salsola species from Iran were examined for their epidermis, seed, and fruit micromorphology. Among them were S. brachiata from section Heterotricha, S dendroides, S. incanescens, and S. orientalis from section Caroxylon, S. kali from section Kali, and S. turcomanica from section Physurus. Epidermal cells are divided into three types. There were diamond, irregular, and polygonal cells, as well as straight and undulated walls. Studied species of Salsola have smooth or sculptured fruit surfaces, and there are three main types of fruit surface ornamentation. There is a significant difference between these species based on the type of hair and density of the fruit. Seed shape and color have little systematic significance. The seed epidermis is composed of polygonal, elongated polygonal, irregular, and diamond cells. Although polygonal and irregular testa cells are most common, their size and shape can provide additional information and useful diagnostic characteristics at both specific and infraspecific levels. For taxonomic separation, the current study provides novel insights at micromorphological levels. RESEARCH HIGHLIGHTS: This article reports halophyte are shown as models for adaptation to extreme habitats. These plants are placed among the ecological communities of xerophytes. Here, for the first time, the microstructural analysis of Salsola has been investigated. Additionally, it provides new insights into plant species' response to extreme conditions, as well as possible adaptation strategies at the micromorphological level.

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By using light microscopy (LM) and scanning electron microscopy (SEM), the pollen grains and foliar epidermal morphology of four species and two varieties of Egyptian Oxalis Linnaeus, 1753 belonging to three sections of the subgenus Oxalis Linnaeus, 1753 were studied. The objective was to determine the importance of pollen and foliar epidermal characters as taxonomic evidence. The current study revealed that the pollen grains of all taxa examined are monads, radially symmetric, isopolar, and of medium size; the shape varied from sub-spheroidal to subprolate. The pollen apertures were tricolpate with ornamented colpal membranes (rugulate, warty, congregated granules). Exine is semi-tectate, with micro-reticulate to reticulate ornamentation, perforate in O. debilis Kunth, 1822. The study also revealed the presence of four types of stomata: actinocytic, anisocytic, anomocytic, and an unusual 4-celled anisocytic. Both abaxial and adaxial epidermal cells were irregular or polygonal in shape, with undulate or straight anticlinal walls and semi-swollen to swollen periclinal walls with dispersed epicuticular wax. Two forms of non-glandular, unicellular trichomes were observed: short clavate and long with a tapering apex and papillate surface. The study further discussed numerical results based on combined morphological, palynological, and foliar epidermal characters. This study is the first report dealing with anatomical and palynological features of the genus Oxalis in Egypt.

Design and additive manufacturing of bionic hybrid structure inspired by cuttlebone to achieve superior mechanical properties and shape memory function

Lightweight porous materials with high load-bearing, damage tolerance and energy absorption (EA) as well as intelligence of shape recovery after material deformation are beneficial and critical for many applications, e.g. aerospace, automobiles, electronics, etc. Cuttlebone produced in the cuttlefish has evolved vertical walls with the optimal corrugation gradient, enabling stress homogenization, significant load bearing, and damage tolerance to protect the organism from high external pressures in the deep sea. This work illustrated that the complex hybrid wave shape in cuttlebone walls, becoming more tortuous from bottom to top, creates a lightweight, load-bearing structure with progressive failure. By mimicking the cuttlebone, a novel bionic hybrid structure (BHS) was proposed, and as a comparison, a regular corrugated structure and a straight wall structure were designed. Three types of designed structures have been successfully manufactured by laser powder bed fusion (LPBF) with NiTi powder. The LPBF-processed BHS exhibited a total porosity of 0.042% and a good dimensional accuracy with a peak deviation of 17.4 μm. Microstructural analysis indicated that the LPBF-processed BHS had a strong (001) crystallographic orientation and an average size of 9.85 μm. Mechanical analysis revealed the LPBF-processed BHS could withstand over 25 000 times its weight without significant deformation and had the highest specific EA value (5.32 J·g−1) due to the absence of stress concentration and progressive wall failure during compression. Cyclic compression testing showed that LPBF-processed BHS possessed superior viscoelastic and elasticity energy dissipation capacity. Importantly, the uniform reversible phase transition from martensite to austenite in the walls enables the structure to largely recover its pre-deformation shape when heated (over 99% recovery rate). These design strategies can serve as valuable references for the development of intelligent components that possess high mechanical efficiency and shape memory capabilities.

Using metal foam and nanoparticle additives with different fin shapes for PCM-based thermal storage in flat plate solar collectors

This research focuses on employing heat transfer enhancement techniques as well as nanoparticles, porous metal foams, and extended surfaces, for the PCM-based thermal energy storage system of a flat plate solar collector. Numerical investigations are carried out for different combinations of the aforementioned techniques, with I-, Y-, and T-shaped fins as the extended surface. The mathematical model is developed with porous media equations, where nanoparticles are embedded in the PCM under the assumption of an equivalent single-phase medium. Results suggest that employing these techniques one by one augments heat transfer performances in terms of reduced melting time. The addition of both metal foam and nanoparticles in the straight wall (case A) reduces melting time by 85.16% when compared to the pure-PCM case, while a 84.38% reduction is reached if only foams are employed. The I-shaped fins (case B) are shown to have an impact too; they provide a 37.07% melting time reduction with only PCM, reaching 89.68% and 86.19% with nanoparticles with foams, respectively. This means that metal foams have a primary role in reducing melting time, where nanoparticles and I-shaped fins become helpful too. Furthermore, by considering all techniques together, the heat storage rate increases by an order of magnitude.