Search Results (28,191)

A thick-lens, structured-light measurement model is introduced to overcome the oversights in traditional models, which often disregard the impact of lens thickness. This oversight can lead to inaccuracies in Scheimpflug camera calculations, causing systematic errors and diminished measurement precision. By geometrical optics, the model treats the camera as a thick lens, factoring in the locations of its principal points and the spatial shifts due to image plane tilting. The model deduces the positional relationship of the thick lens with a tilted optical axis and establishes a linear-structured-light measurement model. Simulations confirm that the model can precisely calculate the 3D coordinates of subjects from image light strip data, markedly reducing systematic errors across the measurement spectrum. Moreover, experimental results suggest that the refined sensor model offers enhanced accuracy and lower standard deviation. Full article

An intelligent optimization technique has been presented to enhance the multiple structural performance of PA6-20CF carbon fiber-reinforced polymer (CFRP) plastic injection molding (PIM) products. This approach integrates a deep neural network (DNN), Non-dominated Sorting Genetic Algorithm II (NSGA-II), and Monte Carlo simulation (MCS), collectively referred to as the DNN-GA-MCS strategy. The main objective is to ascertain complex process parameters while elucidating the intrinsic relationships between processing methods and material properties. To realize this, a numerical study on the PIM structural performance of an automotive front engine hood panel was conducted, considering fiber orientation tensor (FOT), warpage, and equivalent plastic strain (PEEQ). The mold temperature, melt temperature, packing pressure, packing time, injection time, cooling temperature, and cooling time were employed as design variables. Subsequently, multiple objective optimizations of the molding process parameters were employed by GA. The utilization of Z-score normalization metrics provided a robust framework for evaluating the comprehensive objective function. The numerical target response in PIM is extremely intricate, but the stability offered by the DNN-GA-MCS strategy ensures precision for accurate results. The enhancement effect of global and local multi-objectives on the molded polymer–metal hybrid (PMH) front hood panel was verified, and the numerical results showed that this strategy can quickly and accurately select the optimal process parameter settings. Compared with the training set mean value, the objectives were increased by 8.63%, 6.61%, and 9.75%, respectively. Compared to the full AA 5083 hood panel scenario, our design reduces weight by 16.67%, and achievements of 92.54%, 93.75%, and 106.85% were obtained in lateral, longitudinal, and torsional strain energy, respectively. In summary, our proposed methodology demonstrates considerable potential in improving the, highlighting its significant impact on the optimization of structural performance. Full article

The advent of new digital technologies has catalyzed a disruptive technological revolution, fostering significant industrial changes and advancing the green transformation of the economy and society. This paper investigates the influence of digitization on the green transformation of agribusiness firms, focusing on agriculture-related companies listed on the Shanghai and Shenzhen A-share markets from 2013 to 2021. Employing fixed-effect and mediated-effect models, the study examines the mechanisms through which digitization impacts these enterprises. The findings indicate that the relationship between digitization and green transformation in agribusiness is non-linear; a certain threshold of digitization must be achieved before it positively affects green transformation. The effect of digitization on green transformation varies according to the nature of business ownership, company size, supply chain flexibility, and regional environmental regulations. The study reveals that digitization influences green transformation through several mechanisms that promote economies of scale, technological innovation, and structural adjustments. While economies of scale derived from digitization do not directly support green transformation, they facilitate technological innovation and structural adjustments that enhance green initiatives in agribusiness. Full article

Food insecurity remains a pressing issue globally, exacerbated in regions like sub-Saharan Africa, where rural communities face significant challenges in accessing nutritious food. The Eastern Cape Province of South Africa is particularly vulnerable, with high levels of poverty and limited infrastructure contributing to food insecurity among its rural households. In response to these challenges, family food gardens have emerged as a promising strategy to enhance local food production, improve dietary diversity, and foster economic resilience within these communities. Despite the potential benefits of family food gardens, empirical evidence of their effectiveness in mitigating food insecurity at the household level in the Eastern Cape Province is scarce and remains limited. Understanding the factors that influence the success of these gardens, including socio-economic, environmental, and institutional determinants, is crucial for optimizing their impact and scalability. Hence, this study sought to comprehensively explore and investigate the role of family food gardens in improving food security within rural households in the Eastern Cape Province. It seeks to identify the determinants that contribute to the success of these gardens and their potential to alleviate food insecurity. The study made use of a descriptive research design, and the study utilized purposive sampling to gather data from 130 rural households via structured questionnaires. Data analyses incorporated in the study included the Household Dietary Diversity Score and logit regression model to explore the impacts and determinants of family food gardens on food security. The study findings underscore the significant positive contributions of family food gardens to rural communities. They serve as vital sources of fresh crops and vegetables, supplementing household nutrition and providing temporary employment. Constraints identified in the study include financial limitations, theft, water scarcity, inadequate fencing, and limited market access. The study insights highlight the fact that socio-economic and institutional factors such as age, gender, household income, and access to credit are critical influencers of family food garden success. These empirical results offer practical implications for policymakers, governmental agencies, and local communities seeking to promote sustainable agricultural practices and alleviate food insecurity. The research highlights how essential family food gardens are for improving food security among rural families in the Eastern Cape Province. The findings suggest that a joint effort is needed from the government, policymakers, NGOs, and local communities to overcome challenges and make the most of social and economic resources. By working together, these groups can enhance the role of family food gardens, making them a more effective solution for local food production and a stronger defence against food insecurity in the region. Full article

Silicon carbide fiber-reinforced silicon carbide matrix ceramic composites (SiC_f/SiC) are extensively utilized in high-temperature resistant materials in the aerospace industry. This study investigated the influence of stacking structure on the performance of SiC_f/SiC laminated composite plates with film cooling. Initially, the thermal conductivity of cross-piled SiC_f/SiC composites was determined using the laser flash analysis (LFA) method and differential scanning calorimetry (DSC) method. Subsequently, a representative volume element (RVE) model that reflected the stacking structure was established. The anisotropic thermal conductivity of the unidirectional SiC_f/SiC layer was calculated using numerical methods and experimental results. Finally, numerical simulations were carried out to assess the film cooling effectiveness of various stacking sequences and layers. The results showed that the thermal conductivity values predicted by the RVE model for the laminated composite aligned well with the experimental results, and the unidirectional SiC_f/SiC composite thermal conductivities at different temperatures were obtained. The stacking sequence impacted the temperature distribution near the film hole, with the [0-90-0] structure exhibiting a more pronounced effect on film cooling performance compared with the [0-90] and [0-90-90-0] structures. The performance of the film cooling in the laminated SiC_f/SiC composites was consistent across all stacking layers [0-90]₁, [0-90]₂, and [0-90]₃. The maximum difference in overall cooling efficiency was 1.7% between [0-90-0]₁ and [0-90]₁ and [0-90-90-0]₁ Full article

The thrust reverser system stands as the critical component in contemporary large civil aviation, significantly impacting operational efficiency. Owing to their significant weight-reduction benefits, composite materials have emerged as a prominent trend in structural design in recent years. The aim of this research is to optimize the design of the thrust reverser cascade by replacing metal materials with composite materials and to propose a method for conducting mechanical tests on the cascade without a wind tunnel using a new loading scheme and a device that is simpler, more convenient, and less expensive. Focusing on a composite thrust reverser cascade with an inclined blade and beam, the structural and operational load characteristics of the cascade were analyzed and a finite element model incorporating progressive damage analysis was established. The progressive damage analyses of both the global and sub-model elucidated that initial structural degradation manifests near the mounting holes, with the matrix compression failure mode. In addition, a static test method was devised employing levers and hooks. Comparative analyses between test and numerical results demonstrate congruence. The research in this paper provides guidance for the design and testing of the composite thrust reverser cascade. Full article

This article discusses the design of reinforced concrete structures taking into account non-uniform soil conditions, as well as aspects of sustainable engineering. To achieve this, the soil-structure interaction was explicitly introduced into the numerical model of the investigated structure which meets serviceability and the ultimate limit state conditions defined in the relevant Eurocode standards. In the numerical experiment, non-uniform soil conditions, type of foundation (isolated footing, foundation plate), material parameters and size of the cross section of the elements (columns and beams) were analysed. The introduced heterogeneous soil profiles, determined by defining a parametrised, in terms of mechanical properties, spatial model of the layered soil, resulted in nonuniform settlement of the investigated structure. A global analysis of the three-dimensional reinforced concrete structure was carried out taking into account geometric nonlinearity with imperfections and material nonlinearity with creep. The displacement maps of the structure and the risk of collapse due to nonuniform settlement were established. Furthermore, an environmental so called life cycle assessment was performed for each variant analysed of the investigated structure. The innovative nature of the research is based on a joint approach to the problem of soil-structure interaction and the assessment of the carbon footprint of reinforced concrete buildings. This made it possible to determine how the varying soil conditions and different types of foundation affect the amount of material consumed and the carbon footprint associated with the production of reinforced concrete structures. Full article

Traffic problems in China’s river–valley-type cities are prominent. In order to solve these traffic problems, this paper presents four aspects of motorists’ terrain spatial perception according to the characteristics of river–valley-type cities. Based on the structural equation model (SEM), four-dimensional terrain spatial perception is reduced by second-order confirmatory factor analysis. The SEM–Logit model was constructed to analyze the influences of individual socioeconomic attributes, objective built-environment attributes, travel characteristics, and terrain spatial perception on Park and Ride (P&R) use behavior, as well as the moderating effects of terrain spatial perception. The results show that the four latent variables can explain the terrain spatial perception of motorists in river–valley-type cities well. Objective built environments and motorists’ subjective terrain spatial perception have significant impacts on the use of P&R facilities in river–valley-type cities. The terrain spatial perception of motorists in a river–valley-type city moderates the impact of work–residence distance, road slope, river crossing demand, group travel, departure time, and the time saved on P&R use behavior. The research results can provide some reference for solving traffic problems in river–valley-type cities. Full article

Heart failure with preserved ejection fraction (HFpEF) represents a complex clinical syndrome, often very difficult to diagnose using the available tools. As the global burden of this disease is constantly growing, surpassing the prevalence of heart failure with reduced ejection fraction, during the last few years, efforts have focused on optimizing the diagnostic and prognostic pathways using an immense panel of circulating biomarkers. After the paradigm of HFpEF development emerged more than 10 years ago, suggesting the impact of multiple comorbidities on myocardial structure and function, several phenotypes of HFpEF have been characterized, with an attempt to find an ideal biomarker for each distinct pathophysiological pathway. Acknowledging the limitations of natriuretic peptides, hundreds of potential biomarkers have been evaluated, some of them demonstrating encouraging results. Among these, soluble suppression of tumorigenesis-2 reflecting myocardial remodeling, growth differentiation factor 15 as a marker of inflammation and albuminuria as a result of kidney dysfunction or, more recently, several circulating microRNAs have proved their incremental value. As the number of emerging biomarkers in HFpEF is rapidly expanding, in this review, we aim to explore the most promising available biomarkers linked to key pathophysiological mechanisms in HFpEF, outlining their utility for diagnosis, risk stratification and population screening, as well as their limitations. Full article

Impact-oscillatory loading of variable intensity was applied to the VT23M high-strength sheet two-phase titanium alloy in liquid nitrogen. This was carried out to investigate the effect of this loading type on changes in the mechanical properties and structural condition of the alloy upon subsequent static tensioning at normal temperature. Dynamic non-equilibrium process (DNP) realized at a temperature of liquid nitrogen proved to be unable to impair the strength properties of the VT23M titanium alloy compared to room temperature; however, they caused a significant decrease in ductility (down to 16%). The impaired plastic properties of the alloy were shown to entail additional defects in the structural components of the alloy. The authors have found patterns of damage accumulation in the structural components of the alloy depending on the DNP parameters. They are in good agreement with the findings of the fractographic research. Full article

Drawing on Martin’s Multilevel Framework for Analyzing Mathematics Socialization and Identity Among African Americans this study explores the mechanisms that influence Black students’ decision-making processes related to math course taking in high school. Three years of student transcript data for 1561 Black seniors in a Southern California school district were analyzed using descriptive statistics and logistic regression analyses in STATA. The findings reveal factors that impact students’ ability and desire to complete a fourth year of math in high school, interconnected with institutional, structural, identity, and parental factors. One such finding is that accelerated 8th-grade math placement significantly increases the likelihood that a student would enroll in upper-level math coursework, such as “Beyond IM3” courses in high school. The researcher also investigated the influence of the concentration of Black math teachers in a school on the likelihood of a Black student enrolling in a Beyond IM3 math course. The results of this study contribute to an understanding of the limited racial diversity in STEM fields, highlighting the role of math as a major deterrent for Black students’ interest and persistence in STEM. The findings suggest the need for policy and curriculum changes to promote equitable access to advanced math coursework for Black students, especially in the 8th grade. This study also emphasizes the need to address the structural and institutional factors that influence Black students’ decision-making processes related to math course taking in high school. Full article

Urbanization has led to a significant increase in the construction of tall buildings in Canada. The design of tall buildings must ensure structural integrity in withstanding lateral loads, such as wind and earthquakes. The tendency for a specific lateral load to govern building design varies based on the building characteristics, building height, and location of the building. There is a need to identify the governing lateral load (i.e., wind or earthquake) for use in the preliminary design and city-scale assessment. This study examines the governing lateral loads for tall buildings across different Canadian regions through a parametric analysis of a typical high-rise building based on the Commonwealth Advisory Aeronautical Council (CAARC) building. This research evaluates varying building heights, structural systems, and geographic locations under the guidelines of the National Building Code of Canada (NBCC). The analysis identifies the dominant lateral load, providing insights into assessing the existing infrastructure and optimal design strategies for enhancing building sustainability and resilience. Our findings highlight the critical role of geographic location in determining lateral load impacts and the necessity of context-specific design to promote long-term structural performance and environmental sustainability. Full article

The adherence of pathogenic microorganisms to surfaces and their association to form antibiotic-resistant biofilms threatens public health and affects several industrial sectors with significant economic losses. For this reason, the medical, pharmaceutical and materials science communities are exploring more effective anti-fouling approaches. This review focuses on the anti-fouling properties, structure–activity relationships and environmental toxicity of quaternary ammonium salts (QAS) and, as a subclass, ionic liquid compounds. Greener alternatives such as QAS-based antimicrobial polymers with biocide release, non-fouling (i.e., PEG, zwitterions), fouling release (i.e., poly(dimethylsiloxanes), fluorocarbon) and contact killing properties are highlighted. We also report on dual-functional polymers and stimuli-responsive materials. Given the economic and environmental impacts of biofilms in submerged surfaces, we emphasize the importance of less explored QAS-based anti-fouling approaches in the marine industry and in developing efficient membranes for water treatment systems. Full article

Graphene platelets (GPLs) are gaining popularity across various sectors for enhancing the strength and reducing the weight of structures, thanks to their outstanding mechanical characteristics and low manufacturing cost. Among many engineering structures, wind turbine blades are a prime candidate for the integration of such advanced nanofillers, offering potential improvements in the efficiency of energy generation and reductions in the construction costs of support structures. This study aims to explore the potential of GPLs for use in wind turbine blades by evaluating their impact on material costs as well as mechanical performance. A series of finite element analyses (FEAs) were conducted to examine the variations of mechanical performances—specifically, free vibration, bending, torsional deformation, and weight reductions relative to conventional fiberglass-based blades. Details of computational modeling techniques are presented in this paper. Based on the outcomes of these analyses, the mechanical performances of GPL-reinforced wind turbine blades are reviewed along with a cost–benefit analysis, exemplified through a 5MW-class wind turbine blade. The findings affirm the practicality and benefits of employing GPLs in the design and fabrication of wind turbine blades. Full article

The use of additive manufacturing to rapidly test and evaluate solutions to engineering problems has been demonstrated. Selective laser sintering (SLS) is a subset of additive manufacturing that is particularly well suited to producing structural thin wall models and end use parts which can improve the ability to prototype and manufacture certain designs at a substantially lower cost and time compared to current methods. However, a more comprehensive understanding of the material properties of these parts is warranted. The presented research investigates the influence of print orientation and sample thickness on the material properties of printed SLS parts. This novel work involves holding a hatch pattern constant across SLS prints using polyamide 12 material to isolate the anisotropic effects of orientation and thickness. An evaluation of ultimate tensile strength, modulus of elasticity, strain at failure, yield strength, and Poisson’s ratio, and scanning electron microscope fractography are conducted. Transverse strain and Poisson’s ratio are a key aspect that provide insight into the feasibility of building numerical orthotropic models. These data are used to calculate the degree of anisotropy due to both thickness and orientation. The results support the future use of SLS printing and modeling of thin-walled structures, such as scaled structural ship modeling. The presented data provide guidance on the impact of print orientation and thickness that will aid in manufacturing structural parts with intentionally tuned material properties. Full article