Periodica Polytechnica (Budapest University of Technology and Economics)
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Statistical Optimization of Biodiesel Production from Non-edible Pongamia Pinnata Oil
Get PDFBiodiesel production has received considerable attention in the recent past as a renewable fuel to mitigate climate change and for achieving the UN Sustainable Development Goals (SDGs) clean affordable energy and climate action. This research study was based on optimization of the conversion of pongame oil into biodiesel fuel through lab scale batch reactor by acid esterification and alkali transesterification. using Statistical simulation analysis was conducted by Taguchi Orthogonal Array Design, with input factor variables were volume of methanol (20, 25, 30, 40 mL), quantity of catalyst used (0.8, 1.0, 1.8, 2.0 g), volume of acid used (0.2, 0.3, 0.4 0.5 mL), reaction time (55, 60, 90, 120 min) and reaction temperature levels (55, 60, 65, 70 °C). The highest pongamia biodiesel yield was obtained 78.25% experimentally as compared to simulation yield of 84.02% by weight with an error of 5.44%. The highest biodiesel yield was achieved with transesterification carried out for 100 mL pongamia oil under optimized reaction parameters such as methanol amount of 20 mL, KOH amount of 0.8 g, acid amount of 0.2 mL, reaction time 60 min reaction temperature of 55 °C at stirring rate of 700 rpm. The results showed that the properties of the pongamia biodiesel were in compliance with ASTM D 6751 and can be used as blended fuel with petro-diesel in transportation sector, thus reducing environmental pollution causing climate change and global warming
A Review of Microplastic Identification and Characterization Methods in Aquatic Environments
Get PDFPlastic waste has become a major global issue, with over 390.7 million tons of plastic produced in 2021. Because of its durability, low recycling rates, poor waste management, and maritime use, a considerable portion of plastic waste ends up in aquatic environments. Photo-oxidation and other mechanisms degrade plastics into microplastics (MPs), which are particles smaller than 5 mm. MPs can spread through the aerial, terrestrial, and aquatic areas, and running waterways serve as conduits for MP transport across various ecosystems. MPs have been found at various levels of the food web, and animals can ingest, inhale, or absorb them through their skin. MPs pose a significant health risk to flora and fauna, including marine creatures and humans, due to their small size, diverse colors, high abundance, and ability to adsorb antibiotic-resistant pathogens, causing cytotoxicity, acute reactions, undesirable immunological responses, neurotoxicity, and DNA alteration. MPs have a negative economic impact on industries such as agriculture, fishing, tourism, etc. Detecting and quantifying the presence of MPs is therefore critical. The purpose of this paper is to provide an overview of the various techniques and equipment used to detect and characterize MPs in aqueous environments. Identifying and educating the public about the primary sources of plastic pollution can help reduce the number of MPs in the environment
Study on Coordinated Deformation Failure Mechanism and Strength Prediction Model of Rock-lining Concrete
Get PDFShotcrete has been widely used in the excavation of caverns and tunnels as a key load-bearing element in the support system. However, the interfacial stresses and bond strengths within the composite structures formed by the interaction of geologic bodies and tectonic formations are not well understood, which can lead to safety accidents and excessive wastage of support materials in engineering. To address this gap, rock-concrete composite specimens were created using six distinct types of surrounding rocks. The strength law of composite specimens was analyzed, and the uniaxial compressive strength prediction model of composite specimens was derived based on Mohr−Coulomb strength yield criterion. The results show that the uniaxial compressive strength of the composite specimen changes with the change of rock type, which is between the strength of rock and concrete. The uniaxial peak strength and elastic modulus of composite specimens are linearly positively correlated with the ratio (Y) of concrete-rock elastic modulus, which is easily affected by concrete properties. However, the peak strain is linearly and negatively correlated with Y, which is greatly influenced by rock. The rock-concrete interface of the composite specimen plays an important role in the failure of the specimen, which changes the stress transfer state of the composite specimen, produces uncoordinated deformation, and finally causes the failure of the specimen. The theoretical and test value error of the derived composite specimen uniaxial compressive strength prediction model are –1.19%~12.20%, and the theoretical calculation model can be used to predict the uniaxial compressive strength of rock-concrete composite specimens
Investigation on NSM-CFRP Ropes Shear Strengthened RC Beams with an Inclusion of Steel-reinforced Geopolymer in the Compressive Zone
Get PDFThe field of structural engineering was focused on the growth of the latest technologies, materials, and techniques that promoted sustainability, and the use of Carbon Fiber Reinforced Polymer (CFRP) as well as geopolymer was a prime example of this effort. Several investigations and developments in composite materials have generated a wide range of materials that could be used to enhance the strength and durability of structures. This study introduces a novel approach to shear strengthening of reinforced concrete (RC) beams by utilizing Near Surface Mounted (NSM) CFRP ropes in combination with steel-reinforced geopolymer in the compressive zone. The investigation aims to assess the effectiveness of these advanced composite materials in enhancing the structural performance of RC beams, as opposed to conventional steel rebar. Three specimens were subjected to three-point bending tests, demonstrating that the NSM-CFRP ropes, paired with steel-reinforced geopolymer, significantly increased load-carrying capacity. Additionally, the results indicated substantial improvements in ductility and energy absorption. This research contributes to the field by providing a sustainable and efficient alternative to traditional strengthening techniques, supported by a comprehensive assessment of both experimental and numerical findings
Influence of Elevated Temperatures on the Compressive Strength of Concrete Made with Different Types of Aggregate
Get PDFConcrete, the backbone of modern infrastructure, exhibits varying mechanical behaviour that depends on its components, with aggregates playing a crucial role in its strength and durability. This study aimed to investigate the influence of elevated temperatures on the compressive strength of concrete made with different types of aggregate. A comprehensive evaluation of concrete mixes was conducted using quartz, crushed clay bricks, crushed andesite, expanded clay and expanded glass coarse aggregates. For each coarse aggregate type, concrete mixtures were made with the same amount of Portland cement, water-cement ratio, natural sand, and superplasticizer. The effective water-cement ratio and cement content were kept constant in each concrete mixture. The grading and maximum particle size were the same in all concrete mixtures. The results revealed that the type of aggregate has a significant impact on the compressive strength and thermal resistance of concrete, with andesite-containing concrete exhibiting the highest residual strength after heating up to 800 °C and clay brick-concrete displaying the highest strength under elevated temperatures up to 1000 °C. The study also found that the age of concrete affects its strength at elevated temperatures, as concrete in the early stages of hydration is more susceptible to thermal cracking than concrete that has had more time to cure. Generally, the compressive strength of normal-weight aggregates depends on the strength of the parent rock. But in the case of fire (elevated temperature), the cement paste matrix loses its strength, and the aggregates effects become more significant
Estimation of Bond Strength based on Corroded Hinge Beam Specimens: Assessment of Design Guidelines and Analytical Models
Get PDFThe bond between steel and concrete enhances the structural integrity of the building and ensures a cohesive force-resistant system, facilitating composite action between the rebars and concrete. This composite action, in turn, ensures the longevity of the reinforced concrete (RC) structure. The current study focuses on evaluating the performance and comparing design guidelines and analytical models pertaining to hinge beams and pull-out test specimens. The bond strength between concrete and steel was determined by validating 124 experimental datasets collected from the literature. These datasets were based on hinge and pocket beam specimens with varying degrees of corrosion. To facilitate comparison, the international design guidelines and analytical models were designated as G-1 and G-2, respectively. The results indicate that Model M-6 from G-1 and Model M-10 from G-2 outperformed all other models within their respective groups. Upon comparing these two models, M-6 appears to be superior based on selected performance indices. Model M-6 demonstrated an R-value of 0.3275, MAE of 2.29 MPa, RMSE of 2.76 MPa, and MAPE of 39.12% sequentially. Additionally, sensitivity analysis based on the collected dataset was conducted to assess the impact of each parameter.This study offers a comprehensive analysis of bond strength between steel and concrete in RC structures, focusing on hinge beams and pull-out test specimens with varying degrees of corrosion. It introduces superior models for performance evaluation and comparative analysis, highlighting Model M-6 as a novel and robust approach with significant potential for enhancing structural design guidelines
Failure Mechanism of the Toppling Rock Slope with Different Numbers of Free Faces Caused by Excavation: a Case Study in Jiacha Hydropower Station (China)
Get PDFToppling failure is a widespread failure mode in natural and excavated rock slopes and threatens the construction and operation of important infrastructure, such as hydropower and transportation corridors in southwest China. Therefore, comprehending the mechanisms underlying toppling is essential for predicting and preventing relevant landslides. In this study, external deformation monitoring equipment, multipoint deep displacement meter and data acquisition equipment were conducted on the study area to explore the failure model and deformation characteristic of the toppling rock slope with different numbers of free faces. The field monitoring results suggested that the groundwater and unloading effect caused by excavation initiated this slope with one free face, which subsequently deformed gradually at a constant velocity. Thereafter, the displacement vectors progressed toward the free face, and the rock layers gradually slanted downslope. After the slope failed, it was separated into two sections with double and three free faces, respectively. The failure models of these two sections were analyzed numerically, and the results show that the deformation of the double free faces rock slope is primarily caused by wedge sliding along the intersection line of two discontinuities; the three free faces rock mass slope may bend first and then slide along a discontinuity. The study deepens the understanding of toppling rock slopes and provides a theoretical framework for anticipating and avoiding the deformation trends of such slopes
Determining the Criteria Related to the Preference of Contemporary Mosques by the Analytic Hierarchy Process (AHP) Method within the Context of User-centered Design
Get PDFThe concept of user-centered design has recently been accepted in contemporary design teachings and has created new perspectives in the design field. This article aims to evaluate the contemporary mosques built in Türkiye from a user-centered perspective. In this context, first of all, the concept of user-centered design was included and the necessity of a pluralistic environment in decision-making processes was emphasized in order to create an ideal publicity phenomenon. In the context of the conceptual framework created, contemporary mosque examples built in the 21st century were selected and presented to the preference of architect and non-architect participant groups. Decision criteria that are thought to affect the choice of participants are aesthetic value, material and workmanship, dimensions of the building, religious symbols in the building, and the brand value of the building. These factors, which may be effective in the choice of contemporary mosques, were evaluated with the Analytic Hierarchy Process method. Accordingly, it was observed that the main criteria constituting the contemporary mosque preferences of the architect group were aesthetics, the brand value of the building, material, and workmanship criteria. On the other hand, the main criterion constituting the contemporary mosque preferences of the non-architect group was the presence of religious symbols. Accordingly, it was observed that architectural profession ideologies affected and differentiated the reasons for preference. As a result, it was concluded that the ideology of the architectural profession is effective in the construction process of the contemporary built environment
Bibliometric Analysis of Key Issues and Objectives in Environmental, Economic, and Social Sustainable Project Management
Get PDFThe environmental, economic, and social sustainability of construction project management was researched through a literature review in this study. This paper aimed to analyze the trends in studies about issues in sustainable project management and to research the importance and components of environmental, economic, and social sustainability and their interrelationships. In the scope of the bibliometric analysis, the articles were analyzed by their publication years, authors, authors' countries, authors' organizations, and keyword occurrences. Then, the problems in ensuring the sustainability of construction project management and suggestions for overcoming these problems were reviewed. In previous studies, high energy and raw material consumption and waste became the main factors that prevented environmental sustainability. A strong relationship was found between economic sustainability and life cycle cost assessment, and effective stakeholder engagement is considered the major contributor to the social sustainability of construction management. Sustainability regulations and policies, managerial capabilities, and organizational learning also have critical significance for achieving sustainable construction. The dimensions of sustainability in construction management are closely related to one another, and each one is crucial to achieving the other aspects of sustainability in construction projects. Therefore, a comprehensive strategy that takes into account social, economic, and environmental sustainability criteria should be adopted in construction project management
The Urban Morphology of Edirne
Get PDFServing as a cultural center and a border and a university town, Edirne is an important city of Turkey. Edirne also has historical significance as one of the three historical capitals of the Ottoman Empire (the other two are Bursa and Istanbul, respectively). The history of Edirne dates back to the 35th century BCE. This historically prosperous city hosts many monuments from the Ottoman period; however, there are only a few urban and architectural remains from other periods.The creation of the form of the city of Edirne is an example of synoecism, by which a group of small elements in an open pattern of organization, i.e., not subject to a rigid preconceived order, coalesce over time to form a larger entity.The form of Edirne is the result of three distinct types of urban development that are characteristic of three eras in the city's history: Roman/Byzantine, Ottoman, and Modern. The Roman/Byzantine form was incorporated into the Ottoman city that, in turn, was converted into a more homogeneous form in the modern era. Both the Roman/Byzantine and Ottoman patterns persist in the modern city. In this article, the city of Edirne is considered as a whole and the morphology of Edirne is shown to be an organic urban development model