Shielded Metal Arc Welding (SMAW) is the most widely used welding technique in engineering industries. Compared to other arc welding techniques like TIG, SMAW is less heat-concentrating. However, welding thick jobs using SMAW can result in serious issues such as structural distortion due to non-uniform input heat distribution. High thermal stresses and distortions can degrade mechanical properties, similar to high input heat. Fast heat removal may prevent such defects, and different quenching media like sand, water, and oil were used to investigate variations in mechanical properties. High-strength low-alloy steel was selected due to its good weldability and easy availability, which makes it suitable for many industrial applications, such as in the space and defense industries. The tensile testing results showed that oil quenching was superior to other quenching techniques because oil-cooled joints had the highest tensile strength and ductility. However, water-cooled joints showed the highest yield strength, but oil-quenched joints had the highest welding efficiency. The hardness of water-cooled joints in the heat-affected zone and weld zone was greater due to rapid cooling in water. The impact energy of oil-cooled joints in the heat-affected zone was superior to that of other joints. Overall, the mechanical properties of oil-cooled joints were superior and showed better geometric configuration, such as minimal distortions.
Vitória Bomfim, Sergio Nunes, Gilberto Santos Júnior
et al.
Bamboo’s renewability may justify bamboo-reinforced concrete (BRC) structures. For practical applications, the accurate description of BRC flexural behaviour is paramount. Lumped damage mechanics is an interesting alternative among some possibilities on nonlinear models since it is based on key concepts of classic fracture and damage mechanics. Therefore, this paper presents a novel lumped damage model for BRC beams. The model’s accuracy is tested with experiments found in the technical literature. Regarding the analysed experiments, the proposed model presents well-fitted results. Finally, the proposed model is feasible for practical applications, even considering structural reliability analysis like Monte Carlo, since it is easy to implement and presents low computational effort.
Mechanical engineering and machinery, Structural engineering (General)
Anna Gościniak, Everaldo Attard, Ida Judyta Malesza
et al.
Honey is a multifunctional therapeutic agent in wound management with antimicrobial, anti-inflammatory, antioxidant and tissue-regenerative properties. Direct application is limited by high viscosity, variability in composition and instability of bioactive compounds. Advances in biomaterials engineering have enabled the development of honey-based delivery platforms such as nanoparticles, electrospun nanofibers and hydrogels, which improve stability, retention at the wound site and provide controlled release. The review offers a comprehensive overview of honey’s wound-healing mechanisms, evaluates diverse delivery strategies and compares their structural and functional characteristics. Nanoparticles enable targeted delivery and synergistic antimicrobial effects, electrospun mats mimic the extracellular matrix with tunable porosity and hydrogels maintain a moist healing environment with high adaptability. Key challenges include achieving standardization, enhancing mechanical properties and optimizing sterilization methods. Future perspectives emphasize integrating honey-based systems with smart sensors, advanced bioprinting and multifunctional composites to achieve personalized and responsive wound care.
Ahmed Mahmoud, Haitham Mostafa, Tarek Mostafa
et al.
The literature review showed insufficient relevant research on the application of Glass-Fiber-Reinforced-Polymers (GFRP) gratings in the structural elements, while GFRP bars, laminate, sheets, and strips, have been extensively explored. This research aims to present a proposal for a new reinforcing system using GFRP gratings to improve the punching shear resistance of RC flat slabs. Results of seven specimens tested experimentally under vertical static loading are displayed, taking into account the influence of the gratings variables. Test results revealed an improvement in the ultimate load ranging between 9.03% and 27.67% for the specimens strengthened by the proposed GFRP grating system. A Nonlinear Finite Element Analysis (NLFEA) was carried out using the ANSYS program with correlational evaluation using load-deflection response and cracking pattern, which resulted in a good convergence of numerical simulations and experimental performance results ranging from 1.0% to 8.0%. Key parameters, namely the concrete compressive strength, steel reinforcement yield strength, main steel reinforcement ratio, secondary steel reinforcement ratio, column dimensions, slab thickness, concrete cover, and GFRP gratings characteristics, were investigated through a parametric study adopting NLFEA by the ANSYS program, where the output results were compared to the recent code provisions.
Mechanical engineering and machinery, Structural engineering (General)
Linyue Zhang, Edward King, William B. Black
et al.
Noncanonical redox cofactors are attractive low-cost alternatives to nicotinamide adenine dinucleotide (phosphate) (NAD(P)+) in biotransformation. However, engineering enzymes to utilize them is challenging. Here, we present a high-throughput directed evolution platform which couples cell growth to the in vivo cycling of a noncanonical cofactor, nicotinamide mononucleotide (NMN+). We achieve this by engineering the life-essential glutathione reductase in Escherichia coli to exclusively rely on the reduced NMN+ (NMNH). Using this system, we develop a phosphite dehydrogenase (PTDH) to cycle NMN+ with ~147-fold improved catalytic efficiency, which translates to an industrially viable total turnover number of ~45,000 in cell-free biotransformation without requiring high cofactor concentrations. Moreover, the PTDH variants also exhibit improved activity with another structurally deviant noncanonical cofactor, 1-benzylnicotinamide (BNA+), showcasing their broad applications. Structural modeling prediction reveals a general design principle where the mutations and the smaller, noncanonical cofactors together mimic the steric interactions of the larger, natural cofactors NAD(P)+. Engineering enzymes to utilize the noncanonical redox cofactors such as nicotinamide mononucleotide (NMN + ) is challenging. Here, the authors report a growth-based selection platform for NMN + -reducing enzyme engineering and show its application in developing a phosphite dehydrogenase with improved catalytic efficiency.
David M. Ruggiero, Evan C. Bentz, Gian Michele Calvi
et al.
AbstractA growing body of research has shown that reversed cyclic shear loading of reinforced concrete (RC) causes effects that are not accounted for in monotonic behavioral models. Notable among these effects are a reduction in shear strength and significant plastic offsets. This paper presents the General Crack Component Model, a rational, mechanics‐based model that explicitly considers the constitutive behavior of cracks in RC. Cracked RC is treated as a series–parallel system of bonded and unbonded regions, where the crack interfaces have both crack closing hysteresis and a kinematic contact constraint. Validation was performed using data from monotonic and reversed cyclic experiments on panel elements, and has shown that this analytical model is able to accurately capture the salient features of reversed cyclic shear behavior.
Today, the service of Voice over Internet Protocol or (VoIP) is one of the most used service around the globe in many fields, especially with video conferencing applications. Different applications and also many communications companies around the world use the VoIP service. Communication stakeholders aim to keep old customers happy and attract new customers. There was a need for some kind of service quality measures. Metrics are used to quantify the quality of transmission link are known Quality of Service (QoS). Whereas, user satisfaction level is identified by using Quality of Experience (QoE). This paper conducted a simulation model for VoIP service over heterogeneous, using OPNET modeler. This work aims to compare the user satisfaction level of the VoIP service by using different coding schemes in the application level of the User Equipment (UE). The measured QoS parameters over the heterogeneous transmission link were IP packet delay, IP Packet jitter, IP packet loss, MAC layer delay, PHY layer throughput in the network. Additionally, in this simulation model the use of E-Model to assess QoE level using Mean Opinion Score (MOS) metric in predicting the VoIP call quality. The results using the vocoder G.729A during the (30) sec of the voice call simulation time were as follows: Delay 0.57 mSec, Throughput of 290 Kbits/sec, Jitter of 0.02 uSec, MOS value of 3.76. The results using the vocoder G.711 during the same aforementioned time were as follows: Delay 0.25 mSec, Throughput of 70 Kbits/sec, Jitter of 0 Sec), MOS value of 3.08.
Christopher Fapohunda, O. E. Osanyinlokun, A. O. Abioye
The field of structural engineering has in recent times begun to widen its scope from the traditional analysis and design, into the development of new structural materials. This is because the use of non-renewable materials in forming and framing structural projects are raising serious environmental concerns bothering on sustainability of materials, especially cement, to produce structural concrete. Cement has been found to be a major contributor to greenhouse gases which affect the environment negatively. Waste from both the industrial and agricultural industries are gradually becoming sources of material to partly replace cement in concrete because of their pozzolanic properties. The agro-based pozzolanic materials include Rice husk Ash (RHA), Saw dust ash (SDA), Palm oil fuel ash (POFA) amongst others. To further widen the scope and resource base of pozzolanic materials for concreting, ternary blends consisting of agro-based pozzolans are being researched into. These research efforts however appear to be uncoordinated, and thus there is a need to juxtapose these efforts together to see the extent of work done on such ternary blends and present their relevant structural properties. This is with a view to helping identify gaps in such research as a means of preventing wastage of research energies. This paper presents a review of structural properties of some agro-based ternary blends used in structural concrete. It is concluded that more research effort is needed, especially in the development of practical and acceptable guidelines that will aid their application in concrete, for sustainable production of structural concrete.
Architectural engineering. Structural engineering of buildings, Structural engineering (General)
Ioannis Karampinis, Kosmas E. Bantilas, Ioannis E. Kavvadias
et al.
A variety of structural members and non-structural components, including bridge piers, museum artifacts, furniture, or electrical and mechanical equipment, can uplift and rock under ground motion excitations. Given the inherently non-linear nature of rocking behavior, employing machine learning algorithms to predict rocking response presents a notable challenge. In the present study, the performance of supervised ML algorithms in predicting the maximum seismic response of free-standing rigid blocks subjected to ground motion excitations is evaluated. As such, both regression and classification algorithms were developed and tested, aiming to model the finite rocking response and rocking overturn. From this point of view, it is essential to estimate the maximum rocking rotation and to efficiently classify its magnitude by successfully assigning respective labels. To this end, a dataset containing the response data of 1100 rigid blocks subjected to 15,000 ground motion excitations, was employed. The results showed high accuracy in both the classification (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>95</mn><mo>%</mo></mrow></semantics></math></inline-formula> accuracy) and regression (coefficient of determination <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.89</mn></mrow></semantics></math></inline-formula>) tasks.
The work examines the control systems of bridge structures, which are used to assess the condition, forecast repair works, and optimize costs. Bridge management is a key element of infrastructure systems in many countries, as it ensures safety, efficiency, and economic development. Examples of such systems as Pontis, Bridgit, Danbro, etc., are presented, which are used in different countries to assess the condition of bridges and plan repair works. The importance of safety and optimal operation of bridge structures is highlighted. It is highlighted that bridge management systems are necessary tools for countries with different operation and maintenance strategies. The importance of rational management of bridges to ensure safety and sustainable development of transport networks is brought to the fore.
A restoring-force model is a versatile mathematical model that can describe the relationship between the restoring force and the deformation obtained from a large number of experiments. Over the past few decades, a large body of work on the development of restoring-force models has been reported in the literature. Under high intensity cyclic loadings or seismic excitations, reinforced concrete (RC) structures undergo a wide range of hysteretic deteriorations such as strength, stiffness and pinching degradations. These characteristic behaviors can be described by the multi-parameter Bouc-Wen-Baber-Noori (BWBN) model, which offers a wide range of applicability. This model has been applied for the response prediction and modeling restoring-force behavior in structural and mechanical engineering systems, by adjusting the distribution range of this model’s parameters. However, a major difficulty in utilizing the multi-parameter BWBN model is the parameters’ identification. In this paper, a deep neural network model is used to estimate the hysteresis parameters of the BWBN model. This model is one of the most versatile and widely used general hysteresis models that can describe the hysteretic behavior of RC columns. The experimental data of the RC columns used in this paper are collected from the database of the Pacific Earthquake Engineering Research Center (PEER). Firstly, the hysteretic loop obtained from a physical experiment is described by the BWBN model, and the parameters of the BWBN model are identified via a genetic optimization algorithm. Then a neural network is established by a backpropagation (BP) algorithm for associating the identified BWBN model parameters with physical parameters of the RC column. Finally, the regression analysis of the identified parameters is carried out to obtain the regression characteristics of the RC columns. The trained neural network model can directly identify the parameters of BWBN model based on the physical parameters of RC columns, and is effective and computationally efficient for multi-parameter BWBN model identification. The proposed approach overcomes the difficult problem of identifying the parameters of BWBN model and provides a promising approach for a wider application of this multi-parameter hysteresis model.
Abstract CO2 capture and conversion has been prospected as an auspicious technology to simultaneously tackle the rise in global CO2 emission and produce value‐added fuels with the goal of accomplishing carbon neutrality. A sustainable route to achieve this is via the utilization of solar energy, thereby harnessing the abundant and nonexhaustive resource to shift our reliance away from rapidly depleting fossil fuels. Graphitic carbon nitride (g‐C3N4) and its allotrope have earned its rank as a fascinating metal‐free photocatalyst due to its superior stability, high surface‐area‐to‐volume ratio, and tunable surface engineering. By leveraging these properties, robust carbon nitride‐based nanostructures are engineered for photocatalytic CO2 conversion to energy‐rich C1C2 product, which is indispensable in the chemical industry. Thus, this review presents the latest panorama of experimental and computational research on tuning the local electronic, surface chemical coordination environment, charge dynamics and optical properties of low‐dimensional carbon nitride and its allotropes toward highly selective and efficient CO2 photoconversion. To name a few, structural engineering, point‐defect engineering, heterojunction construction, and cocatalyst loading. To advance this frontier, critical insights are elucidated to establish the structure‐performance relationship and unravel primary factors dictating the selectivity of C1C2 molecules from CO2 reduction. External‐field assisted photocatalysis such as with electric (photoelectro‐) and heat (photothermal) is discussed to uncover the synergistic contributions that drive the development in photochemistry. Last, future challenges and prospects are outlined for the potential application of solar‐driven CO2 conversion, along with the scale‐up strategy from the economic viewpoint toward the rational development of high‐efficiency carbon nitride catalysts.
Materials of engineering and construction. Mechanics of materials, Information technology
Several possible definiions of strains in a general shell theory of I.N. Vekua – A.A. Amosov type are considered. The higher-order shell model is definedon a two-dimensional manifold within a set of fieldvariables of the firstkind determined by the expansion factors of the spatial vector fieldof the translation. Two base vector systems are introduced, the firs one so-called concomitant corresponds to the cotangent fibrtion of the modelling surface while the other is defind on a surface equidistant to the modelling one. The distortion appears as a two-point tensor referred to both base systems after covariant differentiationof the translation vector feld. Thus, two main definition of the strain tensor become possible, the firstone referred to the main basis whereas the second to the concomitant one. Some possible simplificationsof these tensors are considered, and the interrelation between the general theory of A.A. Amosov type and the classical ones is shown.
Alkali-activated concrete (AAC) has attracted considerable attention since its first use as an alternative material to the well-known traditional Portland cement concrete (PCC) due to their superior properties and environmental impact. In this paper, a comprehensive review on the present knowledge about the AAC in terms of historical background, environmental impact, constituent materials and characteristics of alkali-activated slag concrete (AASC) is presented. The following topics are reviewed in details for AASC: historical background, environmental impact, constituent materials, reactions mechanism, hydration products, compressive strength, stress–strain behavior, elasticity modulus, Poisson’s ratio, tensile strength, bond characteristics with reinforcing steel bars and behavior under elevated temperature. Most studies have demonstrated the superior mechanical properties of AASC and their applicability in the construction engineering field. Moreover, AASC exhibits bond performance and elevated temperature resistance better than PCC. However, the review reveals that more studies and investigations related to mix design including mix proportions, mixing procedures and curing regime, with which the AASC could demonstrate the best engineering properties, are required.
Olga V. Inozemtseva, Vyacheslav K. Inozemtsev, Gulsem R. Murtazina
Roll-over stability of tall buildings under wind loads is considered. The nonlinear nature of the problem is taken into account, including geometric, physical, and structural non-linearity. The problem is solved on the base of a system of linearized incremental equations of structural mechanics that describes the behavior of a system tall building - foundation soil. Several methods are examined for solving nonlinear problems of roll-over stability, specifically: 1) deformation method of systems equilibrium states tracing; 2) method of linearization of nonlinear equations and systems equilibrium states tracing; 3) method of linearization of nonlinear physical relations of a systems with constructive, static, geometric nonlinearity; 4) method of linearization of nonlinear physical relations of a system with constructive nonlinearity based on nonlinear incremental structural mechanics; 5) method of the deformation process tracing for a physically nonlinear soil base, given the increase of discharge zones and constructive nonlinearity. Each of these methods is used to solve a model task. These tasks take into account roll-over stability of high structures under action of wind loads. In general, the problem of roll-over stability of a high object can be represented as repeatedly nonlinear one with various types of non-linearity. In this regard, in the practice of high-rise buildings designing, it is necessary to develop scientifically and methodically substantiated methods of assessing roll-over stability, considering non-linear factors. Taking these factors into account will make it possible to assess the roll-over stability of a high-rise object more accurate.
Architectural engineering. Structural engineering of buildings
Josh Javor, Jourdan K. Ewoldt, Paige E. Cloonan
et al.
Abstract The structural and functional maturation of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is essential for pharmaceutical testing, disease modeling, and ultimately therapeutic use. Multicellular 3D-tissue platforms have improved the functional maturation of hiPSC-CMs, but probing cardiac contractile properties in a 3D environment remains challenging, especially at depth and in live tissues. Using small-angle X-ray scattering (SAXS) imaging, we show that hiPSC-CMs matured and examined in a 3D environment exhibit a periodic spatial arrangement of the myofilament lattice, which has not been previously detected in hiPSC-CMs. The contractile force is found to correlate with both the scattering intensity (R 2 = 0.44) and lattice spacing (R 2 = 0.46). The scattering intensity also correlates with lattice spacing (R 2 = 0.81), suggestive of lower noise in our structural measurement than in the functional measurement. Notably, we observed decreased myofilament ordering in tissues with a myofilament mutation known to lead to hypertrophic cardiomyopathy (HCM). Our results highlight the progress of human cardiac tissue engineering and enable unprecedented study of structural maturation in hiPSC-CMs.