Search Results (408)

In this paper, the uniqueness of steady Schwarzschild gradient Ricci solitons is studied. The role of the weight functions is analyzed. The generalized steady Schwarzschild gradient Ricci solitons are investigated; the implications of the rotational ansatz of Bryant are developed; and the new Generalized Schwarzschildsteady gradient solitons are defined. The aspects of the weight functions of the latter type of solitons are researched as well. The new most-accurate curvature bound of the steady Ricci gradient solitons is provided. The uniqueness of the Schwarzschild solitons is discussed. The Ricci flow is reconciled with the Einstein Field Equations such that the weight functions are utilized to spell out the determinant of the metric tensor, the procedure for which is commented on following the use of the appropriate geometrical objects. The mean curvature is discussed. The configurations of the observer are issued from the geodesics spheres of the solitonic structures. Full article

A new copper(II) complex was synthesized using chromone-2-carboxylic acid as the main ligand, and coordinated pyridine molecules. The complex was successfully crystallized and structurally characterized by single crystal X-ray diffraction. This revealed a mononuclear structure with a distorted square pyramidal geometry around the central Cu(II) ion. The coordination sphere comprises oxygen atoms from the chromone moiety and nitrogen atoms from pyridine, resulting in a five-coordinate complex. A comprehensive physicochemical characterization was performed using Fourier transform infrared spectroscopy (FT-IR), UV–Vis spectroscopy, elemental (C, H, N), electrochemical (CV) and thermal analysis (TGA/DSC) to confirm the coordination environment and thermal stability of the compound. The complex exhibits distinct spectroscopic features indicative of ligand–metal charge transfer and d–d transitions typical of Cu(II) species. In addition, the synthesized complex was subjected to antimicrobial screening against Gram-positive and Gram-negative bacteria. The compound showed promising antibacterial activity, particularly against Escherichia coli, indicating its potential as a bioactive coordination compound. These results contribute to the growing body of research on metal-based chromone derivatives and emphasize the importance of copper complexes for the development of new antibacterial agents with defined crystal structures. Full article

As digital technology continues to embed and influence everyday life, its social and environmental impacts need to be addressed seriously. This article introduces and clarifies the concept of Ecological Citizenship (EC), defining it as a form of citizenship that extends rights and duties beyond the human social sphere into ecological systems, requiring individuals, communities, and institutions to take responsibility for the environmental consequences of their digital practices. Unlike traditional forms of citizenship tied to legal or territorial boundaries, EC is grounded in shared ecological accountability and civic responsibility. We argue that EC offers a distinctive lens for shaping the evolution of a Sustainable Digital Society (SDS), where digital innovation and sustainability are co-aligned. Through theoretical analysis and case studies, this article examines how EC can support community-based, policy-led, and design-focused approaches towards digital sustainability. We look to highlight ways in which EC can be embedded in digital behaviour, infrastructure, and product design while acknowledging barriers such as the digital divide, unequal resource allocation, and adverse policy settings. This research aims to offer policymakers, technologists, and educators’ pragmatic advice for realising sustainable design, environmental literacy, and universal digital access. The study looks to argue for a more systemic reconsideration of digital development, a consideration which places environmental values at the forefront of technological progress, to ensure that digital transformation is both socially equitable and beneficial to planetary well-being. Full article

LED strips are increasingly used as lighting sources in public and private spaces. However, traditional photometric methods, such as integrating spheres, are unsuitable for measuring their light parameters, often resulting in significant errors and requiring expensive instrumentation or calibration. These errors are typically caused by non-uniform illumination of the internal surface or improper internal geometry, especially when measuring LED sources. This article presents the development of a low-cost integrating device specifically designed to measure LED strips’ light parameters. The device is a compact cube with a volume of less than 1.0 m³. It was tested against alternative methods using an integrating sphere and a goniophotometer in a professional photometric laboratory. The verification results confirmed its effectiveness. The device showed the maximum relative error of luminous flux measurement to be around 5% compared with the accurate, expensive goniophotometric method. For colorimetric measurements, the maximum Correlated Color Temperature (CCT) absolute error was about 35 K for an LED strip with a CCT of 4000 K, indicating a difference imperceptible to the human eye. These results demonstrate the device’s proper relevance in the research and development of LED strip-based lighting equipment to improve lighting equipment quality and control processes. The device is easy to replicate, significantly reducing production and transportation costs, making it an excellent solution for companies and research units seeking a cost-effective method for LED strip measurements. Additionally, the device can measure other light sources or luminaires with reasonably small sizes emitting light in only one hemisphere. The device is the basis of a patent application. Full article

Composite materials are widely used in various fields due to their superior properties. Given their complex internal structures, they are often modeled as homogeneous materials in engineering applications to simplify temperature distribution analysis. The key parameter in this approach is effective thermal conductivity (ETC). Conventional ETC models, based on Fourier’s law or the effective field approach, tend to underestimate temperatures when applied to composites containing internal heat sources, such as nuclear fuels. Preliminary studies have been conducted on ETC models for composite plates and particle-dispersed spheres with internal heat sources, using average temperature as the conserved quantity instead of the heat flux. This study focuses on dispersed disks containing internal heat sources. The finite element method is used to calculate its average-temperature-based ETC. The influence of filler size, filling fraction, and component thermal conductivities on the ETC is analyzed. Additionally, the impact of internal heat sources on ETC is discussed based on the theoretical model for the ETC of a one-dimensional composite plate. This research enhances understanding of ETC in composites with internal heat sources, reveals the connection between conventional and temperature-based ETC models, and provides insights for developing an ETC model for dispersed disks. Full article

The discrete element model of Mactra veneriformis currently employs an oversimplified multi-sphere approach using EDEM’s Hertz–Mindlin model, assuming uniform shell–flesh mechanical properties. This study developed an advanced dual-layer flexible bonding model through comprehensive biomechanical testing. Mechanical properties and shell morphology were experimentally characterized to inform model development. Parameter optimization combined free-fall experiments with Plackett–Burman screening, steepest ascent method, and Box–Behnken RSM, yielding optimal contact parameters: flesh–flesh stiffness (X₁) = 3.64 × 10¹¹ N/m³, shell–flesh interface (X₃) = 1.48×10¹³ N/m³, shell–shell tangential stiffness (X₆) = 3.23 × 10¹² N/m³, and normal strength (X₇) = 8.35 × 10⁶ Pa. Validation showed only 4.89% deviation between simulated and actual drop tests, with hydraulic impact tests confirming excellent model accuracy. The developed model accurately predicts mechanical behavior and shell fracture patterns during harvesting operations. This research provides a validated numerical tool for optimizing clam cultivation and harvesting equipment design, offering significant potential to reduce shell damage while improving harvesting efficiency in bivalve aquaculture systems. Full article

Environmental protection is one of the key challenges facing mankind today. Finding out what young people, referred to as Generation Z, think about this issue is extremely important, as they will be the first to experience the negative effects of environmental degradation. Research has shown that Generation Z has the greatest hope for solutions from the technological sphere. Thus, the economic and political spheres should support the development of technology in this area. The social sphere is rated lowest, which may reflect young people’s personal withdrawal and the delegation of responsibility for the environment’s future to engineers, entrepreneurs, and politicians. It is equally important to learn what constitutes an environmental imperative for Generation Z. It is based on new energy sources, energy producers, and the state’s pursuit of a policy of international cooperation in this area, supported by national legislative activity toward entrepreneurs and citizens. Research has demonstrated the need to raise awareness among young people, with a focus on individuals treated as subjects in their interaction with modern technology. Full article

This study conducts a numerical simulation of the working performance of a single horizontal shaft forced mixer using the Discrete Element Method (DEM). It systematically investigates the effects of blade installation angle, feeding method, mixing speed, and coarse aggregate particle size on the mixing uniformity. A 1:2 scale model was developed, incorporating Newton’s laws of motion and a soft-sphere contact model to simulate the particle trajectories and interactions during mixing. The results indicate that top–bottom feeding enhances mixing efficiency significantly by forming vertical convective circulation, achieving a mixing uniformity above 0.9. A moderate rotation speed of 30 rpm provides the best balance between energy consumption and mixing performance. As the coarse aggregate size increases (from 9 mm to 15 mm), the enhanced particle inertia leads to a decrease in mixing uniformity (from 0.9 to 0.6). Additionally, the discrepancy between simulation and experimental results is less than 0.1, validating the reliability of the model. This research offers theoretical guidance for the structural optimization and parameter selection of single-shaft mixers, contributing to improved mixing efficiency and concrete quality in engineering applications. Full article

The relationship between ecosystem services (ESs) and human well-being (HWB) is a central issue of sustainable development. However, current research often relies on qualitative frameworks or indicator-based assessments, limiting a comprehensive understanding of the relationship between natural environment and human acquisition, which still needs to be strengthened. As an element transferred in the natural–society coupling system, carbon can assist in characterizing the dynamic interactions within coupled human–natural systems. Carbon, as a fundamental element transferred across ecological and social spheres, offers a powerful lens to characterize these linkages. This study develops and applies a novel analytical framework that integrates carbon flow as a unifying metric to quantitatively assess the spatiotemporal dynamics of the land use and land cover change (LUCC)–ESs–HWB nexus in Guizhou Province, China, from 2000 to 2020. The results show that: (1) Ecosystem services in Guizhou showed distinct trends from 2000 to 2020: supporting and regulating services declined and then recovered, and provisioning services steadily increased, while cultural services remained stable but varied across cities. (2) Human well-being generally improved over time, with health remaining stable and the HSI rising across most cities, although security levels fluctuated and remained low in some areas. (3) The contribution of ecosystem services to human well-being peaked in 2010–2015, followed by declines in central and northern regions, while southern and western areas maintained or improved their levels. (4) Supporting and regulating services were positively correlated with HWB security, while cultural services showed mixed effects, with strong synergies between culture and health in cities like Liupanshui and Qiandongnan. Overall, this study quantified the coupled dynamics between ecosystem services and human well-being through a carbon flow framework, which not only offers a unified metric for cross-dimensional analysis but also reduces subjective bias in evaluation. This integrated approach provides critical insights for crafting spatially explicit land management policies in Guizhou and offers a replicable methodology for exploring sustainable development pathways in other ecologically fragile karst regions worldwide. Compared with conventional ecosystem service frameworks, the carbon flow approach provides a process-based, dynamic mediator that quantifies biogeochemical linkages in LUCC–ESs–HWB systems, which is particularly important in fragile karst regions. However, we acknowledge that further empirical comparison with traditional ESs metrics could strengthen the framework’s generalizability. Full article

This study presents the design and implementation of a novel, sensor-based falling-sphere viscometer specifically tailored for measuring the viscosity of engine oil. The equipment utilizes a metallic sphere and two strategically placed sensors to determine the travel time over a predetermined distance within an oil-filled tube. By applying fundamental principles of fluid dynamics, including Stokes’ law, the system accurately calculates the dynamic viscosity based on the sphere’s velocity and the oil’s density. Experimental validation at particular temperature demonstrates the device’s sensitivity and reliability, which are critical for assessing oil degradation and engine performance. The simplicity and low cost of the design make it an attractive alternative to conventional, more complex viscometers. Furthermore, the automated data acquisition system reduces human error and enhances reproducibility of results. Overall, the developed instrument shows great promise for both laboratory research and practical maintenance applications in the automotive industry. Full article

When a high-speed rotating projectile faces high impact loads, the sensitive parts of the control system can get damaged, resulting in operational failure. It is crucial to develop a unique buffer structure that offers impact resistance and has a small contact area. An annularly distributed multi-sphere point contact structure was designed and fabricated on a magnesium alloy substrate based on the Hertz contact theory. The accuracy of the finite element numerical model, constructed using Abaqus/Explicit, was verified through hydraulic impact tests. The impact mechanical properties of the structure were studied by analyzing the influence of the number, diameter, and cavity radius of hemispheres using an experimentally verified finite element model. The axial and radial deformations of the structure were compared and analyzed. The research findings indicate that the deformation and impact resistance of the structure can be greatly influenced by increasing the number of hemispheres, enlarging the hemisphere diameter, and incorporating internal cavities. Specifically, with 6 hemispheres, each with a diameter of Φ 6 mm and a cavity radius of R1.5 mm, the axial and radial deformations are only 1.03 mm and 3.02 mm, respectively. The contact area of a single hemisphere is 7.16 mm². The study offers new perspectives on choosing buffer structures in high-impact environments. Full article

Assessing a city’s level of smartness according to global indices is a relatively new area of investigation. It is useful in encouraging a rethinking of urban digital strategies, although the different approaches to global smart city rankings have been subject to criticism. This paper highlights the methodological features of constructing the Smart City Index (SCI) from the IMD (International Institute for Management Development) based on residents’ assessments, their satisfaction with electronic services, and their perception of the priority of urban infrastructure areas. The Central European cities of the Visegrad region (Prague/Czech Republic, Budapest/Hungary, Bratislava/Slovakia, Warsaw and Krakow/Poland) were chosen as the basis for an in-depth analysis. The architectonics, i.e., the internal system of constructing and calculating city rankings by SCI, is analyzed. A comparative analysis of the technology indicators (e-services) in five cities of the Visegrad region, presented in the SCI, showed the smart features of each city. The progressive and regressive trends in the dynamics of smartness in the cities in the Visegrad region were identified in five urban spheres indicated in the Index: Government, Activity, Health and Safety, Mobility, and Opportunities. This also made it possible to identify certain methodological gaps in the SCI in establishing interdependencies between the data on the residents’ perception of the priority of areas of life in a particular city and the residents’ level of satisfaction with electronic services. In particular, the structural indicators “Affordable housing” and “Green spaces” are not supported by e-services. This research aims to bridge this methodological gap by proposing a model for evaluating the e-service according to the degree of coverage of different spheres of life in the city. The application of the project, as well as cross-sectoral and systemic approaches, made it possible to develop basic models for assessing the value of e-services. These models can be implemented by municipalities to assess and monitor e-services, as well as to select IT projects and elaborate strategies for smart sustainable city development. Full article

Expatriates and missionaries in China played a significant role in the development and transformation of Chinese architecture in the Late Qing period. However, a systematic comparison of their discourses and proposals on Chinese architecture has been hindered by a lack of historical literature and the complexities of fragmented data and methodologies. This article examines and compares the two most influential non-native newspapers: The North-China Daily News in English, edited by expatriates, and The Review of the Times in Chinese, founded by missionaries. By analyzing these two groups’ discourses and narratives on Chinese architecture, the study explores their similarities and distinctions, revealing the characteristics, strategies, attitudes, interests, and opinions of expatriates, missionaries, and non-missionaries in China on the transmission and transformation of architecture knowledge. The research highlights differences in their preferences for specific text types, subjects, and themes on Chinese architecture, as well as their attitudes toward native and foreign architecture, professional education, and architecture regulations in individual and official spheres. Despite these differences, overlapping characteristics and proposals existed among the three groups. The study further investigates the underlying reasons and mechanisms for their similar or divergent mindsets and behavioral patterns, drawing on human responsive psychology rather than relying on postcolonial or cultural theories. Full article

The morphology of electrode materials plays a crucial role in determining the performance of lithium-ion batteries. Traditional computational models often simplify graphite flakes as uniformly sized spheres, which limits their predictive accuracy. In this study, we present a computational workflow that overcomes these limitations by incorporating a more realistic representation of graphite morphologies. This workflow is designed to be flexible and reproducible, enabling efficient evaluation of electrochemical performance across diverse material structures. By exploring different graphite morphologies, our approach accelerates the optimization of material preparation techniques and processing conditions. Our findings reveal that incorporating greater morphological complexity leads to significant deviations from classical model predictions. Instead, our refined model offers a more accurate representation of battery discharge behavior, closely aligning with experimental data. This improvement underscores the importance of detailed morphological descriptions in advancing battery design and performance assessments. To promote accessibility and reproducibility, we provide the developed code for seamless integration with the COMSOL API, allowing researchers to implement and adapt it easily. This computational framework serves as a valuable tool for investigating the impact of graphite morphology on battery performance, bridging the gap between theoretical modeling and experimental validation to enhance lithium-ion battery technology. Full article

In recent years, the concept of the commons has gained relevance across academic, legal and civic spheres as an alternative framework for managing shared resources. Rooted in Elinor Ostrom’s seminal work on collective governance, contemporary debates on the commons increasingly challenge the traditional binary of private versus public ownership by foregrounding the social function of these resources and the role of their communities in their administration. Urban commons, in particular, have emerged as dynamic spaces of experimentation, where local actors reclaim underutilised or abandoned assets and activate them through bottom-up processes of care, cultural production, and civic innovation. While international literature provides a robust conceptual foundation for understanding commoning practices, their practical implementation mostly depends on local specificities, such as legal and social contexts. Despite the important milestone of the Rodotà Commission’s proposal (2007) and Law 168/2017 on collective domains, the Italian regulatory framework remains highly fragmented, with regional and municipal regulations pioneering policies and practices frequently driven by community-led efforts to redefine the use and governance of public assets. This paper contributes to the growing debate on urban commons by investigating how, since 2011, experiences of collaborative care of the commons in Southern Italy have rekindled interest in the issue raised in 2007, highlighting a strong connection between the regulatory and social dimensions of these processes. The study develops a methodological framework—the COMmons Places ASSessment (COMPASS)—to evaluate the enabling conditions and governance dynamics of these processes. The research specifically focuses on five case studies in the Campania region, where diverse actors have mobilised to reclaim and transform public heritage through cultural, social, and creative activities. From the results, insights on collective management practices emerge potentials and criticalities of the analysed governance, as well as of the designed decision-making process and their effectiveness for the open, participatory, and sustainable management of urban commons. Full article