This research explores masonry structural diagnostics and compares the effectiveness of conventional and innovative strengthening methods for masonry walls, arches, vaults, and columns. Applying machine learning and deep learning strategies, this paper presents a review of research results in automatic surface crack detection for unreinforced masonry (URM) walls. The principles of kinematic and static Limit Analysis, under a rigid no-tension model framework, are described. Employing a practical methodology, the manuscript presents a thorough list of papers detailing current research within this field; thus, this paper is beneficial for researchers and practitioners working with masonry structures.
Engineering acoustics often observes vibrations and structure-borne noises transmitted via the propagation of elastic flexural waves within plate and shell structures. Phononic metamaterials, containing a frequency band gap, effectively block elastic waves within particular frequency bands, yet their design is frequently characterized by an iterative trial-and-error process that demands considerable time. Deep neural networks (DNNs) have exhibited proficiency in tackling various inverse problems in recent years. A deep learning-driven workflow for phononic plate metamaterial design is the focus of this study. In order to accelerate forward calculations, the Mindlin plate formulation was used; subsequent to this, the neural network was trained in inverse design. Through the meticulous analysis of only 360 data sets for training and validation, the neural network exhibited a 2% error rate in achieving the desired band gap, achieved by optimizing five design parameters. A designed metamaterial plate exhibited omnidirectional flexural wave attenuation of -1 dB/mm at approximately 3 kHz.
A novel, non-invasive sensor, constructed from a hybrid montmorillonite (MMT)/reduced graphene oxide (rGO) film, was implemented to monitor water absorption and desorption processes in both unaltered and consolidated tuff stones. The film was fashioned from a water-based dispersion that included graphene oxide (GO), montmorillonite, and ascorbic acid, using a casting process. Following this, the GO was subjected to thermo-chemical reduction, and the ascorbic acid was removed by a washing procedure. The hybrid film's electrical surface conductivity, exhibiting a linear dependency on relative humidity, spanned a range from 23 x 10⁻³ Siemens in dry circumstances to 50 x 10⁻³ Siemens under conditions of 100% relative humidity. A high amorphous polyvinyl alcohol (HAVOH) adhesive was utilized to apply the sensor onto tuff stone samples, facilitating good water diffusion from the stone to the film, a process validated by water capillary absorption and drying tests. The sensor's capacity to observe shifts in stone water content is revealed, holding the potential to assess the water absorption and desorption behavior of porous specimens in both laboratory and on-site testing situations.
The paper analyzes studies on the use of polyhedral oligomeric silsesquioxanes (POSS) in various structural forms for polyolefin synthesis and subsequent property modification, specifically (1) their employment in organometallic catalytic systems for olefin polymerization, (2) their role as comonomers in ethylene copolymerization, and (3) their application as reinforcing fillers in polyolefin composites. Subsequently, research on the use of novel silicon compounds, including siloxane-silsesquioxane resins, as fillers for composites derived from polyolefins is presented in the following sections. This paper is presented to Professor Bogdan Marciniec in recognition of his jubilee.
A continuous elevation in the availability of materials dedicated to additive manufacturing (AM) markedly improves the range of their utilizations across multiple industries. 20MnCr5 steel, often employed in traditional manufacturing, displays substantial processability advantages in additive manufacturing applications. This investigation incorporates the selection of process parameters and the analysis of torsional strength within AM cellular structures. NHWD-870 datasheet Analysis of the research demonstrated a substantial inclination towards cracking between layers, a characteristic directly tied to the material's layered architecture. NHWD-870 datasheet In addition, the specimens featuring a honeycomb design achieved the highest torsional strength. The introduction of a torque-to-mass coefficient was necessary to determine the finest characteristics achievable from samples showcasing cellular structures. The honeycomb structure's characteristics were indicative of superior performance, with a 10% lower torque-to-mass coefficient compared to solid structures (PM samples).
As an alternative to standard asphalt mixtures, dry-processed rubberized asphalt mixtures have garnered considerable attention in recent times. Compared to conventional asphalt roadways, dry-processed rubberized asphalt demonstrates improved performance characteristics across the board. Demonstrating the reconstruction of rubberized asphalt pavement and evaluating the pavement performance of dry-processed rubberized asphalt mixtures form the core objectives of this study, supported by both laboratory and field testing. The noise-dampening attributes of dry-processed rubberized asphalt pavement were studied at the sites where the pavement was being built. A prediction of pavement distresses and long-term performance was additionally carried out through the application of mechanistic-empirical pavement design. The experimental determination of the dynamic modulus utilized materials testing system (MTS) equipment. The indirect tensile strength (IDT) test was employed to quantify the fracture energy, thereby assessing the low-temperature crack resistance. The evaluation of asphalt aging involved the rolling thin-film oven (RTFO) and pressure aging vessel (PAV) tests. Asphalt's rheological properties were determined using a dynamic shear rheometer (DSR). The dry-processed rubberized asphalt mixture, according to test results, showcased superior resistance to cracking, with a 29-50% improvement in fracture energy compared to conventional hot mix asphalt (HMA). Concurrently, the rubberized pavement exhibited enhanced high-temperature anti-rutting characteristics. The dynamic modulus demonstrated a remarkable growth, reaching 19% higher. At various vehicle speeds, the noise test established that the rubberized asphalt pavement significantly attenuated noise levels by 2-3 decibels. The rubberized asphalt pavement's performance, as predicted using the mechanistic-empirical (M-E) design approach, showed a decrease in IRI, rutting, and bottom-up fatigue cracking, according to the comparison of the prediction results. Considering all aspects, the dry-processed rubber-modified asphalt pavement demonstrates enhanced pavement performance relative to the conventional asphalt pavement.
A hybrid structure integrating lattice-reinforced thin-walled tubes, featuring varying cross-sectional cell counts and density gradients, was developed to leverage the advantages of thin-walled tubes and lattice structures for enhanced energy absorption and crashworthiness, leading to a proposed crashworthiness absorber with adjustable energy absorption capabilities. Finite element analysis and experimentation were employed to determine the impact resistance of hybrid tubes, featuring uniform and gradient density lattices with different configurations. The study focused on the interplay between lattice packing and the metal enclosure under axial compression, resulting in a 4340% enhancement in energy absorption compared to the sum of the individual tube components. A research study explored the impact of transverse cell density patterns and gradient configurations on the impact-resistant properties of a hybrid structural design. The findings demonstrated that the hybrid structure absorbed more energy compared to a plain tube, showcasing an 8302% increase in its optimal specific energy absorption. Further investigation revealed that the configuration of transverse cells played a crucial role in the specific energy absorption of the uniformly dense hybrid structure, with the maximum observed enhancement reaching 4821% across the diverse configurations. Peak crushing force within the gradient structure was notably impacted by the arrangement of gradient density. NHWD-870 datasheet Quantitative analysis was applied to study how wall thickness, density, and gradient configuration influence energy absorption. This study, using a combined experimental and numerical simulation methodology, presents a unique idea for enhancing the impact resistance of lattice-structure-filled thin-walled square tube hybrid structures under compressive stresses.
Through the digital light processing (DLP) technique, this study showcases the successful 3D printing of dental resin-based composites (DRCs) containing ceramic particles. The printed composites' ability to resist oral rinsing and their mechanical properties were investigated. The clinical efficacy and aesthetic attributes of DRCs have driven extensive study within the field of restorative and prosthetic dentistry. These items, vulnerable to recurring environmental stress, are often prone to experiencing undesirable premature failure. The study investigated how two high-strength, biocompatible ceramic additives, carbon nanotubes (CNTs) and yttria-stabilized zirconia (YSZ), affected the mechanical properties and oral rinsing stability of DRCs. To print dental resin matrices incorporating varying weights of carbon nanotubes (CNT) or yttria-stabilized zirconia (YSZ), the rheological behavior of the slurries was first assessed and then the DLP technique was applied. Through a systematic approach, the mechanical characteristics, including Rockwell hardness and flexural strength, as well as the oral rinsing stability, of the 3D-printed composites, were investigated. The hardness of a DRC with 0.5 wt.% YSZ reached a peak of 198.06 HRB, and its flexural strength was 506.6 MPa, contributing to good oral rinsing stability. This investigation offers a fundamental insight into crafting sophisticated dental materials that feature biocompatible ceramic particles.