Search Results (200)

The building sector significantly contributes to global energy consumption and carbon emissions, primarily due to the extensive use of carbon-intensive materials such as concrete and steel. Mass timber construction, particularly using cross-laminated timber (CLT), offers a promising low-carbon alternative. This study aims to calculate the embodied carbon emissions and biogenic carbon storage of a CLT-based affordable housing project, 340+ Dixwell in New Haven, Connecticut. This project was designed using a honeycomb structural system, where mass timber floors and roofs are supported by mass timber-bearing walls. The authors are not aware of a prior study that has evaluated the life cycle impacts of honeycomb mass timber construction while considering Timber Use Intensity (TUI). Unlike traditional post-and-beam systems, the honeycomb design uses nearly twice the amount of timber, resulting in higher carbon sequestration. This makes the study significant from a sustainability perspective. This study follows International Standard Organization (ISO) standards 14044, 21930, and 21931 and reports the results for both lifecycle stages A1–A3 and A1–A5. The analysis covers key building components, including the substructure, superstructure, and enclosure, with timber, concrete, metals, glass, and insulation as the materials assessed. Material quantities were extracted using Autodesk Revit^®, and the life cycle assessment (LCA) was evaluated using One Click LCA (2015)^®. The A1 to A3 stage results of this honeycomb building revealed that, compared to conventional mass timber housing structures such as Adohi Hall and Heartwood, it demonstrates the lowest embodiedf carbon emissions and the highest biogenic carbon storage per square foot. This outcome is largely influenced by its higher Timber Use Intensity (TUI). Similarly, the A1-A5 findings indicate that the embodied carbon emissions of this honeycomb construction are 40% lower than the median value for other multi-family residential buildings, as assessed using the Carbon Leadership Forum (CLF) Embodied Carbon Emissions Benchmark Study of various buildings. Moreover, the biogenic carbon storage per square foot of this building is 60% higher than the average biogenic carbon storage of reference mass timber construction types. Full article

This study explores the potential of using sustainable materials in brick manufacturing by designing a novel brick mix in the laboratory, incorporating sand, lime kiln dust (LKD) waste, tyre rubber, and ground granulated blast furnace slag (GGBFS) waste. These cementless bricks blended LKD–GGBFS wastes as the binder agent and fine crumb rubber from waste tyres as a partial replacement for sand in measured increments of 0%, 5%, and 10% by volume of sand. Ordinary Portland cement (OPC) and fired clay bricks were sourced from the industry, and their properties were compared to those of the laboratory bricks. Tests performed on the industry and laboratory bricks included compressive strength (CS), freeze-thaw (F-T), and water absorption (WA) tests for comparison purposes. Additionally, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed on the bricks to assess the morphological and mineralogical changes responsible for the observed strengths and durability. The CS and WA values of the engineered bricks were 12, 6, and 4 MPa, and 7, 12, and 15%, respectively, for 0, 5, and 10% crumb rubber replacements. The industry bricks’ average CS and WA values were 13 MPa and 8%, respectively. From the results obtained, the green laboratory bricks passed the minimum strength requirements for load-bearing and non-load-bearing bricks, which can be used to construct small houses. Lastly, the engineered bricks demonstrated strength and durability properties comparable to those of the industry-standard bricks, indicating their potential as a sustainable alternative to help divert waste from landfills, reduce the pressure on natural fine sand extraction, and support eco-conscious brick production for a sustainable environment. Full article

For complex mechanical transmission equipment, shaft bearings are usually enclosed together with the shaft in the internal space of the housing to maintain good sealing and reliability. However, it is difficult to monitor the status of the shaft bearing through external sensors on the housing, while internal sensors face challenges in energy supply and data transmission. Therefore, a piezoelectric transducer ring-based energy harvesting microelectromechanical system (PTR-EH-MEMS) is proposed for the condition monitoring of shaft bearings. Specifically, the piezoelectric transducer ring is designed to convert mechanical vibrations into electrical energy, which simultaneously acts as a self-powered monitoring sensor through energy harvesting. In addition, the MEMS is embedded for piezoelectric data processing and condition monitoring of the shaft bearings. To verify the proposed PTR-EH-MEMS, an experimental investigation is implemented under different conditions. The experimental results demonstrate that the system can achieve the maximum DC output of 0.8 V and the root mean square power of 43.979 μW within 128 s, which can effectively identify early-stage bearing faults frequency through a self-powered mode. By combining energy harvesting with condition monitoring capability, the PTR-EH-MEMS offers a compact and sustainable approach for predictive maintenance in rotating machinery, reducing the reliance on external power sources and enhancing the reliability of industrial systems. Full article

The architectural artefacts, materials, and techniques used for constructing shelters may share some common properties derived from the architectural culture that has evolved within the human species. This article examines the material features and settlement organisations employed in the nest-building activities of early human species and the shelter forms of indigenous peoples residing in sub-Saharan Africa. It questions whether early modern human notions of architectural heritage, which lack substantiation, might have influenced nest construction, typological differentiation, material utilisation, and the transmission of practices to subsequent generations and habitats. The focus is on home-based spatial organisation and the construction of structures. We recognise the need to clarify some fundamental misunderstandings regarding the nature of cultural and archaeological taxonomies, as well as the misuse of analogical reasoning when comparing contemporary hunter–gatherer populations with certain hominin groups. The paper aims to explore whether the early ‘Homo architecture’ in Africa bears any resemblance to that of modern Africans. The central inquiry of this study is whether indigenous architectural artefacts, materials, and techniques have been passed down throughout the evolution of architectural culture. The discussion suggests that the architectural products found in the settlement remains of early Homo species may exhibit characteristics similar to the huts of the indigenous people, who live as hunter–gatherers in sub-Saharan Africa. Discussing the architectural activities of different human species proves fruitful, as early architectural understanding and principles can be adapted to contemporary placemaking scenarios, urban design approaches, and housing models. We believe that, with further evidence, this foundational idea has the potential to be developed further. Full article

Early fault detection in rotating machinery is crucial for optimizing maintenance and minimizing downtime costs, especially in medium-to-large-scale industrial applications. This study presents a multibody model developed in the Simulink^® Simscape environment to simulate the dynamic behavior of medium-sized spherical bearings. The model includes descriptions of the six degrees of freedoms of each subcomponent, and was validated by comparison with experimental measurements acquired on a test rig capable of applying heavy radial loads. The results show a good fit between experimental and simulated signals in terms of identifying characteristic fault frequencies, which highlights the model’s ability to reproduce vibrations induced by localized defects on the inner and outer races. Amplitude differences can be attributed to simplifications such as neglected housing compliancies and lubrication effects, and do not alter the model’s effectiveness in detecting fault signatures. In conclusion, the developed model represents a promising tool for generating useful datasets for training diagnostic and prognostic algorithms, thereby contributing to the improvement of predictive maintenance strategies in industrial settings. Despite some amplitude discrepancies, the model proves useful for generating fault data and supporting condition monitoring strategies for industrial machinery. Full article

In developing countries with high seismic activity, a need exists to construct resilient infrastructure and reduce the housing deficit. Industrialized timber construction and the implementation of seismic isolation interfaces may represent a good alternative to respond to these demands. This paper studies the feasibility of constructing cross-laminated timber (CLT) buildings equipped with frictional pendulum bearings in Chile or similar highly seismic regions. The first part of this study shows a first-order approach for modeling the highly nonlinear behavior of CLT walls using a Smooth Hysteretic Model (SHM). An equivalent model of a base-isolated building was developed using the SHM as well as a physical model of the Friction Pendulum System in order to assess the seismic performance of CLT buildings with frictional isolators. The second part of this research presents and discusses the results of a broad parametric analysis concerning the seismic performance of base-isolated CLT buildings. The seismic assessment was carried out by deriving fragility curves and including the uncertainty linked to the seismic input and the friction coefficient of the isolation system. Constructing lateral resistant systems based on CLT walls presents a feasible alternative for buildings in high seismic hazard areas. Excellent seismic performance is achieved if the superstructure’s is designed with a reduction factor of 1, or if the superstructure’s fundamental period ranges from 0.6 to 0.9 s and is designed with a reduction factor of 2 and ductility capacity of 6 or more. An excellent seismic performance can be obtained for larger reduction factor values if the superstructure has middle to high maximum ductility capacity. Full article

The integration of 3D printing with smart infrastructure presents a transformative opportunity in urban planning, construction, and engineering, enhancing efficiency, flexibility, and sustainability. By leveraging additive manufacturing alongside digitalization, artificial intelligence (AI), and the Internet of Things (IoT), this technology enables the creation of customized, lightweight, and sensor-embedded structures. This work analyzes both the advantages and challenges of applying 3D printing in smart infrastructure, focusing on material optimization, rapid prototyping, and automated fabrication, which significantly reduce construction time, labor costs, and material waste. Applications such as 3D-printed bridges, modular housing, and IoT-integrated urban furniture exhibit its potential in contributing towards resilient and resource-efficient cities. However, despite these benefits, significant challenges hinder large-scale adoption. Issues of scalability, particularly in the fabrication of large and load-bearing structures, remain unresolved, requiring advancements in high-speed printing techniques, material reinforcement strategies, and hybrid construction methods. Furthermore, regulatory uncertainties and the absence of standardized guidelines create barriers to implementation. The lack of comprehensive building codes, certification protocols, and quality assurance measures for 3D-printed structures limits their widespread acceptance in mainstream construction. Overcoming these limitations necessitates research into AI-driven process optimization, multi-material printing, and international standardization efforts. By assisting towards overcoming these challenges, 3D printing has the potential to redefine urban development, making infrastructure more adaptive, cost-effective, and environmentally sustainable. This work provides a critical evaluation of the current capabilities and limitations of 3D printing in smart infrastructure towards achieving full-scale implementation and regulatory compliance. Full article

The assembly clearance between the bearing housing and rolling mill stand affects the roll change and rolling stability. In order to improve the accuracy and real-time measurement of the bearing housing clearance of the rolling mill, four kinds of measuring methods were designed, namely the laser ranging method, external force measuring method, internal force measuring method, and eddy current ranging method, and the characteristics of the four measuring methods were introduced, respectively. The real-time measuring experiment of bearing housing clearance was carried out in a 100 mm two-high mill in laboratory and a 1580 mm four-high hot tandem mill in the Qian’an Iron and Steel Company. The results show that clearance measurement technology is helpful to improve the accuracy of real-time measurements and can provide guidance for the clearance control work. Finally, based on the real-time measurement technology of bearing housing clearance, the control strategy of bearing housing clearance was developed. This technology is of great significance to realize the fine management of rolling mill clearance and to improve the intelligence level of rolling mill systems. Full article

Condition monitoring systems are widely used in gearboxes. Gears are one of the most crucial components for power transmission. Hence, the optimal sensor positions for condition monitoring of gears should be investigated to maximize reliability and to minimize costs. This work aims to analyze measured signals from rotating sensors at gears and compare them to signals from housing sensors to find the suitable positions for condition monitoring of the gears. Additionally, the rotational speed and external torque influences on the signal quality have been investigated. These are compared with a simulation model, which considers the vibration excitation from the gear mesh and bearings. The results show that the rotational speed affects the amplitude of the excitation. On this basis, we also investigate the amplitudes of the excitation frequencies of interest. The ratio of the amplitudes of these frequencies related to the mean values of the measurement signals is called the peak-to-mean ratio (PMR), and this PMR corresponds to the speed which is of interest for automatic fault detection in the gearboxes. Additionally, the simulation results show that the intensity of the vibration with the gear mesh frequency hardly reduces during transmission through the tapered roller bearings. Full article

Background: Transtibial prosthetic sockets are critical components in the complete assembly of a prosthetic, as they form the major load-bearing parts by housing the residual limb of a prosthesis user. Conventional procedures for manufacturing these sockets require repeated iterations and manual casting, baking, and drying, which often lead to longer processing and waiting times. Additive Manufacturing (AM) enables the creation of bespoke designs with meticulous control over the socket’s shape, thickness, and material composition. Method: To design and propose an optimal socket design to a lower-limb prosthetic user based on their preference of activity such as walking, running, and jumping, we investigated seven materials—Polypropylene (PP) standard material for conventional socket fabrication, Polylactic-acid-plus (PLA+), Polyamide (PA) Natural, Polyamide-6-Glass-Fiber (PA6-GF), Polyamide-copolymer (CoPA), Polyamide-6-Carbon-Fiber (PA6-CF), and Polyamide-12-Carbon-Fiber (PA12-CF)—that have AM compatibility by subjecting them to heavy external loading and evaluating their von Mises stress–strain behavior. Result: Using Finite Element Analysis (FEA), we evaluated a single-material design and a combination design with two materials—one major (low cost) and one minor (higher cost)—to optimize a composition that would bear heavy external loads without yielding. A maximum load-bearing capacity of 3650 N was achieved with the combination of PLA+ and 31.54 vol% PA6-CF (30.23 weight%, 99.13 g), costing about USD 14 for the total socket material. Similarly, a combination of PLA+ with 31.54 vol% PA6-GF (30.76 weight%, 101.67 g) exhibited a maximum load-bearing capacity of 2528.91 N. Conclusions: The presence of high-strength CF and GF in minor compositions and at critical locations within the transtibial socket are the suggested reasons for these enhanced load-bearing capacities, due to which these sockets could be used for undertaking a wider range of activities by the prosthesis users. Full article

The traditional Malay house is a significant component of the Malay cultural heritage and a key example of vernacular architecture. It is characterised by its outstanding design and the various styles across Malaysia. Traditional Malay houses experience deterioration and damage due to various threats, resulting in many houses being abandoned. A thorough structural evaluation is crucial for preserving the traditional Malay house. This research aimed to develop guidelines for the global structural evaluation of the Malay house. A case study approach was adopted in this research. Site visits, visual surveys, geometrical surveys, and dilapidation surveys were also employed. The research involved structural analysis using SAP2000. The results revealed the vulnerability of the houses to lateral forces, sliding, and differential settlement under scouring. The key structural members have adequate load-bearing capacity, which might be compromised under certain conditions, as in the case of deterioration. These results helped identify potential safety concerns and led to the development of guidelines for the global structural evaluation of Malay houses. The guidelines cover analysis inputs and modelling techniques in terms of material, geometry, joints, and foundations. They address load criteria and the impacts of flooding and scouring on the structural behaviour of the traditional Malay house. The guidelines, finally, recommend that structural checks be considered. This research contributes to traditional Malay house preservation by providing an evidence-based approach to designing preservation measures. Full article

There has been long-standing debate as to whether Kami Fumi-e (paper images to be trampled on) had actually been used in image trampling sessions as part of the 250-year persecution of Christianity enforced by the Tokugawa Shogunate. Sacred images of Christianity officially recorded to have been trampled on are housed in the permanent collection of the Tokyo National Museum and are almost uniquely made of metal alloy. The controversy regarding paper images, apart from the medium being considered unsuitable for such extreme use, was fueled by the appearance of a significant number of them in museum collections and institutions worldwide in the 20th century. Most of the prints bear dates from different eras of the Edo period, sometimes hundreds of years apart; therefore, long-standing arguments regarding their authenticity marked the last century. In order to distinguish later copies from potentially original pieces, if ever existed, XRF, Raman, and FTIR analytical techniques were used to study the materials characterizing them. In addition, detailed observation of the main visual features (overall design composition, inscriptions, paper support, etc.) was carried out to highlight potential discrepancies that could pair with scientific evidence and lead to a definitive conclusion. Full article

Maintenance strategies such as condition-based maintenance and predictive maintenance of machines have gained importance in industrial automation firms as key concepts in Industry 4.0. As a result, online condition monitoring of electromechanical systems has become a crucial task in many industrial applications. Motor current signature analysis (MCSA) is an interesting noninvasive alternative to vibration analysis for the condition monitoring and fault diagnosis of mechanical systems driven by electric motors. The MCSA approach is based on the premise that faults in the mechanical load driven by the motor manifest as changes in the motor’s current behavior. This paper presents a novel data-driven, MCSA-based CM approach that exploits autoregressive (AR) spectral estimation. A multiresolution analysis of the raw motor currents is first performed using the discrete wavelet transform with Daubechies filters, enabling the separation of noise, disturbances, and variable torque effects from the current signals. AR spectral estimation is then applied to selected wavelet details to extract relevant features for fault diagnosis. In particular, a reference AR power spectral density (PSD) is estimated using data collected under healthy conditions. The AR PSD is then continuously or periodically updated with new data frames and compared to the reference PSD through the Symmetric Itakura–Saito spectral distance (SISSD). The SISSD, which serves as the health indicator, has proven capable of detecting fault occurrences through changes in the AR spectrum. The proposed procedure is tested on real data from two different scenarios: (i) an experimental in-house setup where data are collected during the execution of electric cam motion tasks (imbalance faults are emulated); (ii) the Korea Advanced Institute of Science and Technology testbed, whose data set is publicly available (bearing faults are considered). The results demonstrate the effectiveness of the method in both fault detection and isolation. In particular, the proposed health indicator exhibits strong detection capabilities, as its values under fault conditions exceed those under healthy conditions by one order of magnitude. Full article

This paper presents an analysis of the dynamic characteristics observed and studied during the startup process of a gas foil radial bearing. It utilizes a comparison of both experimental data and three-dimensional fluid–solid interaction computational fluid dynamics simulations to investigate a gas foil bearing with three bump-type pads. The analytical model employs the fluid–structure interaction finite element method to examine the relationship between the components and the thin working fluid film within the bearing. This analysis was conducted under various operational conditions, including ambient pressure and temperature, shaft rotational speed, and the load applied to the shaft within the bearing. The foil structure of the bearing was modeled by representing the top and bump foils as a series of linear springs that are interconnected with the rigid housing. Meanwhile, the hydrodynamic pressure distribution acting on the top foil was modeled as a gas film operating under steady-state lubrication conditions. The comprehensive three-dimensional multi-physics model was developed using a commercial computer-aided engineering package, enabling independent finite element calculations for both fluid and solid domains. Following these calculations, the model exchanged analysis results across the interface between domains, allowing simulations to continue until the system achieved a quasi-steady state. An in-house experimental system was designed to evaluate the performance of the gas foil bearing under different working conditions, including the load applied to the shaft and the rotational speed. The experiment investigated the operational state of a gas foil radial bearing under ambient pressure (1 bar), ambient temperature (303 K), rotational speeds ranging from 1.5 to 9.5 krpm, and a load of 0.5602 kgw. Some operational conditions of the bearing were defined as boundary condition inputs for the simulation model. The model’s results, notably the predicted lift-off rotational speed of the bearing, show strong alignment with results from in-house experiments. Full article

Fecal glucocorticoid metabolites have been used to evaluate responses to stressors in captive adult polar (Ursus maritimus) and grizzly (Ursus arctos horribilis) bears. However, there is a lack of physiological information on juvenile bears in captivity that could help expand the current understanding of their development and welfare. To address these questions, we tracked fecal glucocorticoid metabolites (FGMs) and behavior for 15 months in two polar bear cubs born at the Detroit Zoo, one who was mother-reared (Astra) and one who was hand-reared (Laerke), and one rescued grizzly bear cub (Jeb) reared at the Zoo. To allow access to a social partner during key developmental stages, Laerke and Jeb were housed together for eight months. Daily opportunistic samples were analyzed for fecal cortisol metabolites using an enzyme immunoassay and compared against behavior, social proximity, and environmental data gathered from 15 min focal observations. Based on a combination of generalized linear mixed models and Wilcoxon and Kruskal–Wallis tests, we found no significant variation in mean FGMs between Astra and Laerke, but both had significantly different mean FGMs compared to Jeb. We found that Laerke had higher FGM concentrations when she spent more time engaged in all-occurrence social negative behaviors and lower FGMs when engaged in social positive behaviors. For Jeb, FGMs were lower when in social proximity and higher following separation from Laerke. These data provide novel insights into the physiological states of juvenile bears during key stages and contribute to the growing body of information on polar and grizzly bear development. Full article