Monolithic Structures Research Articles

Assessment of quality indicators in construction

Introduction. Ensuring proper quality of construction is one of the pressing challenges of our time. Consumers expect cheap products from developers in the form of commercial or residential real estate that meet all the required quality indicators. Most accidents in monolithic construction occur due to non-compliance with technological procedures at low temperatures. The purpose of the study is to develop a framework for assessing the quality of concrete work at subzero temperatures (during winter work) based on the results of studies of technological parameters of winter concreting, their impact on the quality and safety of erected monolithic structures of industrial and civil buildings (structures).Materials and methods. The study used the method of approximating distributions of random variables, expert estimates, the theory of multiple principles, and mathematical statistics. The experiments were carried out in the laboratories of the Don State Technical University, as well as in the conditions of actual concrete work on a construction site in winter. The work uses a correlation-regression analysis of the dependence of the organizational and technological causes of inconsistencies (factors) and quality indicators of concrete work production. Statistical information on structural damage and collapse of buildings during their operation was processed. To make organizational and technological decisions to improve the quality of concrete work, it is proposed to take the influence of defects on the load-bearing capacity of buildings as an indicator of the quality level.Results. Using practical and expert methods, the most significant reasons (factors) for the occurrence of inconsistencies in the level of quality of concrete work production have been established. Factors have been identified that have the greatest influence on the change in the load-bearing capacity and reliability of buildings and structures being erected when performing the main types of construction and installation work. The nomenclature of technological quality indicators during winter production of concrete work, their influence on quality substantiated, and methods for assessing the quality of winter concreting technology are developed. Quantitative indicators of the quality of construction of monolithic reinforced concrete structures were obtained.Discussion and conclusions. The practical value of the work lies in the development of a methodological tool for creating a regulatory framework for operational construction control of the production of monolithic and prefabricated monolithic construction and installation works under conditions of exposure to low temperatures, as well as for acceptance control of compliance of completed construction projects with quality requirements. Proposals are given for establishing regulatory tolerances, ways to improve the manufacturability of the equipment used, a new method for designing winter concreting technology, and a quality control method focused on ensuring structural safety have been developed. By developing the research, it is further possible to develop methods for calculating technology parameters taking into account technological variability, as well as establish new indicators to regulate the required level of quality and safety of buildings being built.

Analysis of structures and movement parametres of self-climbing platforms and development prospects

Introduction. For high-rise building construction self-climbing platforms based on hydraulic drive are used, lifting the formwork for monolithic structures. These lifting mechanisms differ in structures, characteristics and parameters. There is a need to introduce high-tech equipment in the industry. To create self-climbing platforms for high-rise construction, it is necessary to conduct research in the field of operation of lifting vehicles.Materials and methods. Platforms based on climbing profile for the analysis were used. The design features of the specified type of platforms were considered. The main parameters were speed of lifting, maximum lifting height and load capacity.Results. Graphical data on the main structural elements and the lifting process were obtained the specified type of platforms. Graphical data on hydraulic system is provided and the mechanism of movement is considered in detail. The basic formulas for determining the platform lifting speed and maximum load capacity required for the choosing of specified lifting vehicles.Discussion and conclusion. Existence of factors affecting the lifting speed of platforms and their maximum load capacity provides grounds for the development of a method for calculating and designing the considered transport and technological equipment in Russian Federation. One of the ways to develop this lifting equipment is integration of accessory mechanisms into their structure for fulfilling additional works during the construction of high-rise buildings, in this way forming a single transport and technological complex.

Study and optimization of process parameters for deformation machining stretching mode

Monolithic thin-structure parts with intricate geometric designs are employed in a variety of aeronautical, medical, marine, and automotive applications, which include the moldlines of the fuselage, turbine blades, impellers, avionic shelves, irregular fins, prostheses, bone and joint support, and skull plates. The deformation machining process is the solution to this challenging and difficult-to-manufacture high-quality components with intricate narrow geometries at competitive prices. The aim of the present study is to assess the effect of process parameters of the deformation machining process wherein a thin, floor-like structure is created by milling and is then formed using a single-point incremental forming tool. Investigation involves the design and development of tooling required for the process followed by feasibility checking of the process. To examine the impact of different process parameters on the process response, the experiments were carried out using the design of experiments. The findings of this study indicate that different process parameters, including spindle speed, tool diameter, incremental step depth, and feed rate, have a substantial impact on the process response, like thickness, surface finish, and hardness. Uneven and non-uniform surface patterns during SEM indicate that it is needed to examine the impact of process parameters. This research involves the feasibility study of a new hybrid technique of deformation machining. Conventionally, a metallic structure is produced by joining various components through welding or by fastening. These methods require additional expenditure on equipment, storage, floor space, human resources, etc., with higher lead time. Joining increases weight and reduces fatigue strength. The creation of monolithic structures can eliminate all these disadvantages.

Coalescence of Porous Coordination Cages into Crystalline and Amorphous Bulk Solids.

Discrete porous coordination cages are attractive as a solution processable material whose porosity is not predicated on a network structure. Here, we leverage the peripheral functionalization of these cage structures to obtain 12 novel, solution processable, porous coordination cages that afford crystalline and amorphous single-phase millimeter-scale monolithic bulk structures (six of each) upon solidification. These structures are based upon prototypal metal-organic polyhedra [Cu24(5-x-isophthalate)24] (where x = NH2, OH), wherein meta-substitution of linker ligands with acyl chloride or isocyanate moieties afforded amide and urethane functional groups, respectively. These porous cage structures were obtainable via direct synthesis between a metal salt and a ligand as well as postsynthetic modification of the cage and formed monoliths following centrifugation and drying of the product. We rationalize their self-assembly as colloidal packing of nanoscale cuboctahedral cages through weak interactions between their hydrophobic alkyl/aromatic surfaces. In general, amorphous solids were obtained via rapid precipitation from the mother liquor upon methanol addition, while crystalline solids could be obtained only following further chloroform and pyridine additions. The structure of the materials is confirmed via gas sorption and spectroscopic methods, while powder X-ray diffraction and transmission electron microscopy are used to determine the nature of these bulk solids.

Деструктивные явления при некачественном прогреве монолитных железобетонных конструкций

The growth of the number of the building floors inevitably leads to an increase in the construction period and, consequently, to the need for monolithic reinforced concrete structures in winter. Electric heating by means of heating cables is the most widespread method of concrete curing in winter conditions in the Central region of Russia. The risk of defects in monolithic reinforced concrete structures increases under certain conditions. This risk is related to various types of technological process faults. The main types of monolithic structures defects have been repeatedly described. But there are practically no papers describing the types and causes of defects associated with failures during electric heating of concrete. The author has developed a block diagram of the main defects, and the main reasons for their occurrence have been identified. The paper summarizes the experience gained during two winter periods at the construction sites of Moscow city belonging to unique buildings and structures. Operational and quality inspection of the construction was performed. The author identified groups of defect causes: cable installation and installation errors; heating regime errors. The author identified specific types of defects for each group, and also gave recommendations on their avoidance in the future. The paper provides a ‘check list’ of parameters that must be checked during electric heating with heating cables. The checklist shows the control points that minimize the risk of defects.

3D macroporous MXene/sodium alginate aerogels with “brick-concrete” structures for highly efficient solar-driven water purification

Interfacial water evaporation, powered by solar energy, holds great promise to extract freshwater from seawater on a global scale. It has the potential to address the world's water scarcity challenges using renewable energy. While the ideal design of evaporator materials is critical to the interfacial vaporization desalination, tailoring the structures and compositions of solar evaporators and figuring out the structure/composition-performance relationship of evaporators remains unexplored. Herein, 3D macroporous “brick-concrete” MXene/sodium alginate aerogel (MSA) evaporators were designed and fabricated with constant MXene content and varying polymer loading. The as-made MSAs show sodium alginate-dependent evaporating performance with an optimum evaporation rate of 3.28 kg m−2 h−1 (1 sun). This exceptional rate is attributed to several factors, including enhanced light absorption, optimized pore sizes, reduced enthalpy of evaporation and improved water transport. The water molecule states and hydrogen bonding network in the aerogels can be tuned by their compositions, resulting in the reduced evaporation enthalpy, the monolithic structures with controlled thermal conductivity facilitate the exploitation of environmental energy, leading to the high evaporation rate. Our study not only establishes design principles for achieving superior evaporation performance, but also sheds light on the relationship between structures, compositions, and performance of solar evaporators.

Ballistic performance of flexible structures composed of UHMWPE fibers and airbag: Effects of the stacking order

A series of flexible structures incorporating an airbag and ultra-high molecular weight polyethylene (UHMWPE) fiber panels were designed as temporary architectures to offer both ballistic protective functions and lightweight constructions. Three primary structural configurations, monolithic structures (airbag or UHMWPE panel alone), bi-layer structures (airbag/ UHMWPE panel and UHMWPE panel/airbag), and sandwich structures (UHMWPE panel/airbag/ UHMWPE panel) were tested. A T12A carbon tool steel sphere with the diameter of 12.7 mm was utilized as the ballistic threat within an impact velocity range of 0–500 m/s. Investigations into the effect of stacking order on ballistic performance were carried out experimentally and numerically. The failure characteristics, ballistic limits, energy dissipations, impact processes and interaction effects of these structures are discussed. To facilitate the establishment of numerical models for impact analysis using ABAQUS, a material constitutive model of thermoplastic polyurethanes (TPU) including strain rate effect was developed. The numerical models of the monolithic single-sheet UHMWPE panel and airbag for impact analysis were subsequently verified by experiments in terms of impact processes and ballistic limits. The results reveal that arranging a few layers of UHMWPE panels in front of the airbag can improve the collapse ballistic limit while maintaining the failure ballistic limit. The inclusion of an airbag reduces the energy dissipation efficiency of composite structures. The potential to enhance ballistic protection through the combination of airbags and UHMWPE panels is highlighted. Stress dispersion and deformation restraint are identified as significant factors influencing the ballistic performance of the composite structures.

Application of Hierarchically Porous Chitosan Monolith for Enzyme Immobilization.

Enzyme immobilization is a crucial technique for improving the stability of enzymes. Compared with free enzymes, immobilized enzymes offer several advantages in industrial applications. Efficient enzyme immobilization requires a technique that integrates the advantages of physical absorption and covalent binding while addressing the limitations of conventional support materials. This study offers a practical approach for immobilizing α-amylase on a hierarchically porous chitosan (CS) monolith. An optimized CS monolith was fabricated using chemically modified chitin by thermally induced phase separation. By combining physical adsorption and covalent bonding, this technique leverages the amino and hydroxy groups present in CS to facilitate effective enzyme binding and stability. α-Amylase immobilized on the CS monolith demonstrated excellent stability, reusability, and increased activity compared to its soluble counterpart across various pH levels and temperatures. In addition, the CS monolith exhibited a significant potential to immobilize other enzymes, namely, lipase and catalase. Immobilized lipase and catalase exhibited higher loading capacities and enhanced activities than their soluble forms. This versatility highlights the broad applicability of CS monoliths as support materials for various enzymatic processes. This study provides guidelines for fabricating hierarchical porous monolith structures that can provide efficient enzyme utilization in flow systems and potentially enhance the cost-effectiveness of enzymes in industrial applications.

Parametric Analysis Of Wave-Induced Forces And Overtopping On Composite Vertical Breakwaters With Retreated Crown Wall

Composite vertical breakwaters are monolithic structures often used to protect port basins, especially in deep-water conditions. At present, the design of these structures is mainly based on Goda's formulae (Goda, 2010) or on the probabilistic design tools (PROVERBS) proposed by Oumeraci et al. (2001), while their hydraulic performance in terms of overtopping can be predicted by using the tools described in the EurOtop Manual (EurOtop Manual, 2018). Due to the size of these structures, the optimization and the improvement of the hydraulic performances (e.g. reduction of wave loads, wave overtopping, etc.) of these breakwaters can lead to significant economic saving. Typically, designers try to make small geometric changes without modifying the main geometrical dimensions of these structures. One of these technical solutions consists in placing the cast-in-situ concrete crown wall at a retreated position with respect to the front caisson face. It is assumed that the retreat of the crown wall, for geometric reasons, induces a time lag between the loads acting on the lower front external seawall face and on the crown wall of the caisson; furthermore, this could introduce a change in the pulsating nature of the loads, introducing also turbulent dissipations, consequently reducing the reflection coefficient and modifying the wave overtopping. To the best authors’ knowledge, in the literature there is a lack of guidelines to consider the effects of crown wall retreat in terms of wave actions and hydraulic performance of the structure. Recently, Romano & Bellotti (2023), based on physical model tests, provided a first experimental insight on the increase/reduction of the wave loads acting on deep water vertical breakwaters with retreated crown wall.

Control of Pore Sizes in Epoxy Monoliths and Applications as Sheet-Type Adhesives in Combination with Conventional Epoxy and Acrylic Adhesives.

Materials with monolithic structures, such as epoxy monoliths, are used for a variety of applications, such as for column fillers in gas chromatography and HPLC, for separators in lithium-ion batteries, and for precursor polymers for monolith adhesion. In this study, we investigated the fabrication of epoxy monoliths using 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (TETRAD-C) as the tetrafunctional epoxy and 4,4'-methylenebis(cyclohexylamine) (BACM) as the amine curing agent to control pore diameters using polyethylene glycols (PEGs) of differing molecular weights as the porogenic agents. We fabricated an epoxy monolith with micron-order pores and high strength levels, and which is suitable for the precursors of composite materials in cases where smaller PEGs are used. We discussed the effects of the porous structures of monoliths on their physical properties, such as tensile strength, elongation, elastic modulus, and glass transition temperatures. For example, epoxy monoliths prepared in the presence of PEGs exhibited an elastic modulus less than 1 GPa at room temperature and Tg values of 175-187 °C, while the epoxy bulk thermoset produced without any porogenic solvent showed a high elastic modulus as 1.8 GPa, which was maintained at high temperatures, and a high Tg of 223 °C. In addition, the unique adhesion characteristics of epoxy monolith sheets are revealed as a result of the combinations made with commercial epoxy and acrylic adhesives. Epoxy monoliths that are combined with conventional adhesives can function as sheet-type adhesives purposed with avoiding problems when only liquid-type adhesives are used.

Effective C4 Separation by Zeolite Metal-Organic Framework Composite Membranes.

Inorganic zeolites have excellent molecular sieving properties, but they are difficult to process into macroscopic structures. In this work, we use metal-organic framework (MOF) glass as substrates to engineer the interface with inorganic zeolites, and then assemble the discrete crystalline zeolite powders into monolithic structures. The zeolites are well dispersed and stabilized within the MOF glass matrix, and the monolith has satisfactory mechanical stabilities for membrane applications. We demonstrate the effective separation performance of the membrane for 1,3-butadiene (C4H6) from other C4 hydrocarbons, which is a crucial and challenging separation in the chemical industry. The membrane achieves a high permeance of C4H6 (693.00±21.83 GPU) and a high selectivity over n-butene, n-butane, isobutene, and isobutane (9.72, 9.94, 10.31, and 11.94, respectively). This strategy opens up new possibilities for developing advanced membrane materials for difficult hydrocarbon separations.

Effective C4 Separation by Zeolite Metal–Organic Framework Composite Membranes

AbstractInorganic zeolites have excellent molecular sieving properties, but they are difficult to process into macroscopic structures. In this work, we use metal–organic framework (MOF) glass as substrates to engineer the interface with inorganic zeolites, and then assemble the discrete crystalline zeolite powders into monolithic structures. The zeolites are well dispersed and stabilized within the MOF glass matrix, and the monolith has satisfactory mechanical stabilities for membrane applications. We demonstrate the effective separation performance of the membrane for 1,3‐butadiene (C4H6) from other C4 hydrocarbons, which is a crucial and challenging separation in the chemical industry. The membrane achieves a high permeance of C4H6 (693.00±21.83 GPU) and a high selectivity over n‐butene, n‐butane, isobutene, and isobutane (9.72, 9.94, 10.31, and 11.94, respectively). This strategy opens up new possibilities for developing advanced membrane materials for difficult hydrocarbon separations.

Microwave heterostructures in the form of submicron Y<sub>3</sub>Fe<sub>5</sub>O<sub>12</sub> films on non-oriented ferroelectric ceramic substrates: synthesis, properties, and prospects for applications

In the work monolithic structures of yttrium iron garnet (YIG, Y3Fe5O12) with a thickness of about 2 μm were obtained on ferroelectric ceramic substrates based on PbZr0.45Ti0.55O3 (PZT) and Ba0.4Sr0.6TiO3 (BST). The Y3Fe5O12 layer was deposited by ion beam sputtering deposition on substrates 400 μm thick by sputtering a polycrystalline Y3Fe5O12 target with with argon ions. The heterostructures were crystallized by annealing in air at a temperature of 820 °C for 5 min. The results of the characteristic X-ray radiation method showed that the elemental composition of the monolithic heterostructure corresponds to the specified one. During X-ray studies, it was found that the YIG crystallization process is completed and the resulting structure is single-phase. The results of magnetic and ferromagnetic resonance studies indicate the possibility of using the obtained heterostructures in logic circuits based on spin waves with low scattering, in memory elements, as well as in electrically controlled microwave devices.

A Contemporary Secure Microservices Discovery Architecture with Service Tags for Smart City Infrastructures

The re-conceptualization of fundamental elements from traditional monolithic structures to the Microservices framework has emerged as a vital vision for the future of IoT systems. This transformation is pivotal in addressing the present and future challenges faced by IoT systems and enhancing their overall operational qualities. The adoption of Microservices in IoT introduces an array of opportunities for innovative research, which collectively contribute to its feasibility and success. The transition from traditional systems to Microservices in IoT brings forth various complex challenges that need to be effectively addressed. Key challenges include ensuring seamless Microservice discovery, efficient API gateway management, scalable distribution services, reliable uniform service discovery, robust containerization, and stringent access control mechanisms. These challenges encompass both technical and security-related aspects, necessitating innovative solutions to overcome them. To overcome these challenges, our research proposes a secure service discovery architecture that integrates security measures at each stage of the discovery process. This methodology employs advanced encryption techniques, authentication protocols, and authorization mechanisms to safeguard Microservices in IoT. A mathematical framework is introduced to formalize and implement these security measures, ensuring a robust and reliable approach to Microservices adoption in the IoT ecosystem. In the experimental phase of our research, we aim to validate the proposed secure service discovery architecture through a series of rigorous tests and simulations. We will assess its performance, scalability, and security efficacy under various real-world scenarios and IoT use cases. Experimental results and performance metrics will be analyzed to provide empirical evidence of the viability and effectiveness of our proposed methodology in addressing Microservices-related challenges in IoT systems.

Thermochemical Oxygen Pumping with Perovskite Reticulated Porous Ceramics for Enhanced Reduction of Ceria in Thermochemical Fuel Production

AbstractWithin this work, reticulated monolithic foams and granules made from CaMnO3 − δ and strontium substituted variations are demonstrated to significantly improve the performance of a water splitting redox oxide when employed as a thermochemical oxygen pumping material. Two different process procedures are tested and foams made from Ca0.9Sr0.1MnO3 − δ with a strontium content of 10% outperform all other specimens in both process configurations. Additionally, the performance of Ca1 − xSrxMnO3 − δ with varying strontium content as a thermochemical oxygen pumping material is studied by means of a newly developed theoretical process model. While the model does not precisely predict the excellent experimental performance of strontium‐substitute compositions, it provides valuable insights into the impact of geometry and structure on the specimen's performance in thermochemical oxygen‐pumping processes. This work demonstrates the practical application of monolithic 3D structures made entirely from perovskite material in thermochemical oxygen pumping processes and provides a process model that can serve as basis for material screening and process optimization in future work.

Facile Synthesis of Poly(methyl methacrylate) Silica Nanocomposite Monolith by In Situ Free Radical Polymerization of Methyl Methacrylate in the Presence of Functionalized Silica Nanoparticles.

Novel porous poly(methyl methacrylate) (PMMA) silica nanocomposites have been produced by utilization of polymerization-induced phase separation in a simple one-pot approach. A facile free radical polymerization of MMA in the presence of surface methacrylate-functionalized silica nanoparticles was carried out in ethanol-based solvents, successfully producing novel, morphologically designable porous nanocomposite monoliths. Differing from standard free radical polymerization in solution, a mixture of good and poor solvents (ethanol/N,N-dimethylformamide ratio) for the resulting polymer was used to trigger spinodal phase separation. The influence of monomer concentration, as well as solvent composition, on the morphology of the resulting porous polymers has been investigated. Porous monolith structures composed of connected particles and co-continuous morphologies were observed under a scanning electron microscope depending on the polymerization conditions. The resulting polymers were insoluble and showed swelling characteristics in some organic solvents that are capable of dissolving regular PMMA, indicating covalent bonds between the functionalized silica nanoparticles and the polymer chains. The presence of silica particles in the final polymer was proven via an ATR-IR analysis. The glass transition temperature of the present PMMA-silica nanocomposite was higher than that of the conventional PMMA. The porous polymer immersed in a mixed organic solvent showed coloration induced by the Christiansen effect.

Carbon Inverse Opal Macroporous Monolithic Structures as Electrodes for Na-ion and K-ion Batteries

Highly ordered three-dimensionally structured carbon inverse opals (IOs) produced from sucrose are stable electrodes in sodium-ion and potassium-ion batteries. The walls of the ordered porous carbon structure contain short-range graphitic areas. The interconnected open-worked structure defines a conductive macroporous monolithic electrode that is easily wetted by electrolytes for Na-ion and K-ion systems. Electrochemical characterization in half-cells against Na metal electrodes reveals stable discharge capacities of 25 mAh g−1 at 35 mA g−1 and 40 mAh g−1 at 75 mA g−1 and 185 mA g−1. In K-ion half cells, the carbon IO delivers capacities of 32 mAh g−1 at 35 mA g−1 and ∼25 mAh g−1 at 75 mA g−1 and 185 mA g−1. The IOs demonstrate storage mechanisms involving both capacitive and diffusion-controlled processes. Comparison with non-templated carbon thin films highlights the superior capacity retention (72% for IO vs 58% for thin film) and cycling stability of the IO structure in Na-ion cells. Robust structural integrity against volume changes with larger ionic radius of potassium ions is maintained after 250 cycles in K-ion cells. The carbon IOs exhibit stable coulombic efficiency (>99%) in sodium-ion batteries and better coulombic efficiency during cycling compared to typical graphitic carbons.

Fast sintering of titania monoliths for photocatalytic degradation of organic micropollutants

Scalable solutions to efficiently remove organic micropollutants from water are urgently needed to address the significant adverse health effects their accumulation causes on the environment and in humans. Solutions based on slurries of titania (TiO2) nanoparticles, while effective in the lab, cannot be scaled up due to cost and environmental concerns. Conversely, titania monolithic structures are not photoactive as high sintering temperatures result in the predominance of the non-photoactive rutile phase. In this work the combination of 3D printing and fast sintering allowed, for the first time, to obtain titania monoliths which are mechanically stable and retain their photoactivity. The latter arises from the anatase-rich composition of the monoliths, a result not possible using convectional sintering methods. To demonstrate their photoactivity, the porous monoliths were used in a recirculating flow reactor to degrade primidone, a widely used drug and ubiquitous micropollutant. Results for the best performing monolith showed a quantum yield value of 1.1 × 10−5and an electrical energy per order value of 13 kWh m−3, both significantly outperforming literature data. These results show a clear route to scaling-up the fabrication of photocatalytically active titania monoliths capable of effectively degrading organic micropollutants in water, whose presence is a major health and environmental hazard.

Assessment of Organizational and Technological Reliability Monolithic Works

Every year in the construction process new technologies are introduced, the use of new building materials increases, a large number of contractors are involved, with a significant increase in the scale of construction and the need to ensure the reliability of construction. There arises a necessity to forecast and correct activities of construction organizations, to give adequate assessments of the adopted organizational and technological solutions (OTS), which, asa rule, leads to a decrease in the prescriptive term of construction. Monolithic structure construction process design is closely connected with the necessity of clear and correct choice of the necessary organizational-technological solutions. Depending on the made decisions it is possible to estimate the reliability of monolithic works. This in its turn gives the possibility to forecast the terms of production, the cost of monolithic works on the stage of design of dwelling buildings and industrial objects directly. The article offers a methodology for calculating the evaluation of organizational and technical reliability of the process of monolithic structures. For the successful performance of monolithic works it is necessary to ensure the reliable functioning of all participants of the process from designers to construction teams. The article presents the calculation of organizational and technological reliability index (OTR) of monolithic works. To calculate the index the author proposed a model and introduced the concept of reliability of the considered process of monolithic works as a probability of achieving the final goal. At the same time, the process of monolithic works performance both for residential and civil objects is taken as a complex stochastic system, which includes a set of co-dependent relations. The application of the assumed approach for the calculation of organizational and technological reliability of monolithic works with small changes, refinements can be applied to the calculation of other works in the construction of buildings and structures throughout the life cycle of construction. At the same time, this methodology makes it possible to obtain a numerical value of reliability assessment, which is very relevant when choosing organizational and technological solutions.

Thermal and hydraulic performance of Al alloy-based 3D printed triangular microchannel heatsink governed by rough walls with graphene and alumina nanofluids as working liquid

Microchannel heat sinks (MCHS) are known for providing enhanced cooling performance but their fabrication requires complex and multi-step processes. The recent development of additive manufacturing has enabled the fabrication of state-of-art monolithic structures that had been impossible to build using conventional methods. In this work, a monolithic cross-flow triangular cross-section MCHS was fabricated from aluminum alloy (AlSi10Mg) using the Direct Metal Laser Sintering (DMLS) process. The microchannel wall surface roughness was measured and the cross-section shrinkage of the microchannels was compared with the initial design hydraulic diameter of 500 µm–1000 µm. The MCHS with an initial design hydraulic diameter of 750 µm possessed a relative wall surface roughness, R a of 7.7%. The triangular cross-section hydraulic diameter underwent a shrinkage of 15.2% and 5.3% in terms of the reduction in angle between adjacent side alloys. Experiments were conducted for Reynolds numbers between 50 and 275 with nanofluids containing graphene and Al2O3 nanoparticles in water/water +10% ethylene glycol; these were compared with their respective base fluids. The Poiseuille number indicated that flow was laminar developed with base fluid and laminar developing with nanofluid as coolant. Despite providing the lowest thermal resistance, the graphene nanoparticles in water created the greatest pressure drop leading to a reduced performance coefficient. Al2O3 nanoparticles in water/water +10% ethylene glycol were found to have 7.7% and 20% better performance coefficients than their respective base fluids.