New doctoral dissertation

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New doctoral dissertation

May 14, 2026

黑料不打烊 Library invites you to follow the published new dissertations. The dissertation 鈥炩€� prepared at 黑料不打烊 by Juozas Mas臈nas. The dissertation was prepared in 2021鈥�2026. Scientific consultant 鈥� Prof. Dr Juozas Valivonis.

The dissertation was defended at the public meeting of the Dissertation Defence Council of Civil Engineering in the Aula Doctoralis Meeting Hall of 黑料不打烊_独家黑料_吃瓜网51爆料 at 10 a.m. on 14 May 2026.

Layered concrete structural elements consist of two or more concrete layers cast at different times and often with varying material properties. These elements can offer significant structural, architectural, and environmental advantages, provided that composite behaviour between the layers is maintained. The key factor governing this composite action is the performance of the interface between the concrete layers. In practice, the interface may exhibit reduced initial stiffness and will inevitably experience stiffness degradation as cracking develops. As the interface loses stiffness, the individual layers begin to perform more independently, leading to a reduction in the overall flexural stiffness of the layered element. Despite this, most current design codes lack an analytical approach for calculating deflections that account for interface partial shear connection, and such methods remain limited in scientific literature. In practice, standard reinforced concrete flexural analysis is typically suggested. This dissertation proposes an analytical approach to determine the flexural stiffness (deflection) of layered concrete elements, accounting for the varying interface stiffness as the element deforms. The approach begins with an interface behaviour model, which describes the relationship between interface shear stress and layer slip. This model is characterised by four distinct stages of interface behaviour, each governed by different shear mechanisms, interface material properties, and a differential shrinkage effect. It remains applicable from the onset of interface loading through to significant interface deformations. From the shear stress-slip relationship, the variable interface shear stiffness modulus is derived. This modulus is then used in the second stage of the analytical approach: the built-up layers deflection estimation model. This model allows for the calculation of deflection in layered elements while accounting for the stiffness of individual layers, the composite stiffness of the entire element, evolving geometries due to cracking, and the changing interface shear stiffness. Experimental and numerical analyses were conducted on concrete interfaces and layered concrete elements subjected to bending. The interface analysis provided insights into the effects of concrete strength, connector geometry and strength, differential shrinkage, interface roughness, and its overall geometry on interface strength, stiffness, and the intensity of different shear mechanisms. The analysis of layered beams and slabs clarified the cracking behaviour of individual concrete layers, the distribution of shear stress along the interface, the influence of connector inclination, and layer depth on flexural capacity and cracking patterns. Experimental results were used to validate the proposed analytical approach, showing strong agreement and confirming its effectiveness for analysing layered concrete elements.

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New doctoral dissertation

黑料不打烊 Library invites you to follow the published new dissertations. The dissertation 鈥濫conomic assessment of agricultural sector in the context of sustainability鈥� 聽prepared at 黑料不打烊 by Ahmad Bathaei. The dissertation was prepared in 2021鈥�2026. Scientific consultant 鈥� Prof. Dr Dalia 艩treimikien臈. The dissertation was defended at the public meeting of the Dissertation Defence Council of the Scientific Field of Economics in the Aula Doctoralis Meeting Hall of 黑料不打烊_独家黑料_吃瓜网51爆料 at 2 p.m. on 14 May 2026. This dissertation explores the economic assessment of the agricultural sector within the broader context of sustainability, with a particular focus on the Baltic States. As agriculture continues to play a central role in rural economies and food security, integrating sustainability principles into economic evaluation has become increasingly important. Despite numerous studies on sustainable agriculture, there remains a lack of comprehensive frameworks that combine multidimensional indicators with region-specific data and stakeholder input. This research develops an integrated methodology for gap-filling to identify, evaluate, and prioritise sustainability indicators, and to develop the indicators across the economic, environmental, and social domains. The work comprises four interconnected pieces of research. First, a systematic review of the literature conducted under the SALSA (Search, Appraisal, Synthesis, and Analysis) and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocols identified 101 indicators, which will serve as a basis for the subsequent analyses. Second, a focused review of the conjunction of renewable energy and agriculture identified 84 indicators and demonstrated the importance of energy efficiency and resource circularity for sustainable farming practices. Third, this research applied the TOPSIS (Technique for Order of Preference by Similarity to the Ideal Solution) method for the first time to rank sustainability indicators in the Baltic States, integrating expert opinions with Eurostat statistical data. The assessment examined the environmental priorities of soil health, water and fertiliser management, and the social and economic dimensions. Finally, eleven economic indicators identified through the Delphi and the Best鈥揥orst Method (BWM) were selected and ranked, and investment intensity, income diversification, labour productivity, and market access were found to be the most important economic indicators of agricultural sustainability. The studies allow for drawing up evidence-based policy formulation and strategic planning. The dissertation presents a new model for evaluating sustainable agriculture. It provides a practical, regionally specific, and empirically precise understanding of the sustainability problem. The framework helps policy makers, researchers, and practitioners, particularly in post-transition economies, identify areas that require intervention and investment, such as Lithuania, Latvia, and Estonia. The adaptability of this work to other parts of the world facing the same problem is a means of assisting countries in achieving sustainable agricultural development through economic evaluation. Doctoral dissertation readers can search via聽黑料不打烊 Virtual Library.

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