Journals Published by Vilnius Tech
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Equivalents of the Riemann hypothesis involving the Gram points
Get PDFThe Riemann hypothesis (RH) on zeros of the zeta-function , , states that all zeros of in the strip 0< \sigma < 1 lie on the line . Several equivalents of RH are known. In the paper, we obtain equivalents of RH in terms of self-approximation of by shifts , , where is the sequence of the Gram points
Comparative efficiency testing of a composite hydraulic cylinder
Get PDFThe paper points to the increasing use of composite materials in hydraulic components. This entails many benefits, such as weight reduction which is particularly important in aviation. However, new problems arise with the use of new materials. With regard to a hydraulic actuator whose cylinder is made of a composite material, one of the issues is ensuring adequate efficiency, comparable to that of a steel cylinder. The efficiency of a hydraulic actuator is related to friction processes in the structural nodes and to leaks in the cylinder. This paper presents the original results of volumetric, hydraulic-mechanical and total efficiency tests of three designs differing in the material used as a liner of a cylinder. The materials considered as liner were CFRP composite, polyurethane F180. In addition, a steel liner was considered as a reference. Variations in actuator efficiency depending on the liner used were indicated
Disadvantageous effects of vibrations on the micro-hydraulic relief valve: experimental approach
Get PDFThe paper discusses the negative impact of external mechanical vibrations, which lead to the malfunction of drive systems, particularly affecting hydrostatic drives. The hydraulic system components feature a spring-supported control element that vibrates due to external mechanical vibrations, leading to pressure pulsation. The resulting pressure pulsation causes many unfavorable characteristics of hydraulic system operation. The positive displacement pump is shown as the main source of pressure pulsation in a hydraulic system. For selected frequencies of external mechanical vibration close to the natural frequency of the valve control element, the resulting pressure pulsation far exceeds the pressure pulsation resulting from the displacement pump. This paper presents selected results showing pressure pulsations as a consequence of the displacement pump and external mechanical vibrations acting on the pressure-relief valve
Review of the design and condition monitoring of overhead power distribution conductors
Get PDFBushfires, also known as wildfires in some parts of the world, is a major hazard with significant risks to communities and the environment. Such fires can initiate from a number of sources including lightning. However, one of the possibilities for initiating bushfires is faults in the power system. Faults in conductors can happen overtime and monitoring is essential for effective maintenance and avoiding unnecessary power failures. Simultaneously, assessing conductor reliability is critical for powerline asset management. This paper comprehensively reviews conductor design and monitoring in the distribution network. Various conductor types and applications are described using population statistics from the Australian power distribution network. Furthermore, the design approach in the Australian Standard is briefly explained and further design methodologies are assessed, emphasizing the progress of innovative approaches. Additionally, potential conductor failure modes in Australia’s distribution network are identified. The paper also outlines different condition assessment methods and explores their advancement. Finally, possible models for evaluating conductor reliability are examined, underscoring their benefits in accounting for weather-induced impacts
Decision-making of corporate clients during strategic briefing process according to knowledge acquisition types
Get PDFOrganizational clients with limited experience in strategic briefing often face challenges in identifying building project outcomes for achieving a competitive edge in their business. Communication with practitioners during strategic briefing facilitates clients in acknowledging the importance of timely decision-making and being involved in a knowledge spiral to acquire the information. Knowledge-acquisition by clients can lead to behavioral changes, both within themselves and their organizations. This study classifies knowledge-acquisition types (KATs) and investigates the potential for rational decision-making in briefings. A framework, developed through a literature review and practical insights, is validated by introducing the Action Research approach with stakeholders across ten building projects in sectors: manufacturing, retail, and public enterprises. The framework, refined during interactions among researchers, clients and service providers, identifies KAT1 as the domain knowledge, KAT2 as the administrative knowledge, and KAT3 is the facility knowledge of clients. KAT4, the difference between groups with and without construction-project experiences, relates to the procedures for achieving strategic objectives. This involves understanding the project and organizational characteristics through knowledge accumulation and managing client interactions to ensure successful projects. The Action Research framework facilitates knowledge exchange among clients and practitioners, empowering corporate clients to effectively achieve strategic objectives through group decision-making
Sub-activity analysis by using wristband-type wearable health devices to measure construction workers’ physical demands
Get PDFUnderstanding and managing the physical demands of construction workers is critical to their safety, health, and productivity. Construction tasks, especially cyclic and non-cyclic activities are highly variable. Cyclic tasks involve repetitive actions, which if not well-distributed, can lead to cumulative fatigue and long-term health issues. Conversely, non-cyclic tasks are unpredictable and irregular, making it challenging to allocate workloads effectively. Despite these challenges, few studies have investigated continuous physical demands for both task types, particularly in dynamic, onsite construction environments. Filling this gap is essential for developing practical strategies to improve workload allocation, mitigate health risks, and optimize workforce management. This study addresses this critical gap by using lightweight wearable wristbands equipped with heart rate (HR) biosensors to monitor workers’ activities without disrupting their tasks. The percentage of heart rate reserve (%HRR) is calculated to quantify the continuous physical demands of 10 construction workers performing both cyclic and non-cyclic tasks across two construction sites over three weeks. Results revealed significant workload variations between task types and work patterns. For instance, stationary tasks (‘work without moving’) strongly influenced %HRR for rebar workers, while dynamic tasks (‘work with moving’) had a greater impact on form workers. Additionally, while some daily average %HRR values fell below the 33% threshold, extended high-intensity periods (exceeding 40% HRR for over 30 minutes) posed potential health and safety risks for construction workers. This research demonstrates the potential of long-term HR monitoring to address workload disparities, ensure balanced task allocation, and reduce health risks for construction workers
Multi-Criteria Decision Methods in the evaluation of social housing projects
Get PDFThe evaluation of social housing projects is a complex process that requires the consideration of multiple factors and dimensions to make informed decisions to address the emerging challenges of contemporary urbanization and achieve more resilient and sustainable communities. This study\u27s comprehensive review of the existing literature on the use of Multi-Criteria Decision Methods (MCDM) in evaluating social housing projects was undertaken. An exhaustive analysis of a bibliographic set of 93 articles published between 1994 and march 2025 was conducted. It was noted that the articles analyzed different phases of the construction process, from planning and design to implementation and maintenance. Significant trends in the use of MCDM were identified, highlighting the prevalence of crisp number-based approaches and the emergence of modern techniques such as fuzzy logic and neutrosophic logic. Among the most widely used methods were AHP and TOPSIS, both pioneering methods. In addition, there was an increasing focus on sustainability in project evaluation, encompassing environmental, social, economic, and technical aspects. Consequently, this literature review serves as a guide for incorporating multi-criteria evaluation strategies to improve constructability, especially in social housing projects, taking sustainability into consideration
Decoding the knowledge space of ‘Architectural and Urban Traditions’ utilising a metadata framework
Get PDFThis article explores the discourse on Architectural and Urban Traditions (AUT), examining its evolution expressions, and manifestations as a knowledge space. Utilising a Metadata Framework (MF) based on six lines of inquiry–scale, discipline, geographical diversity, typology, governance, and investigation methods–this research systematically examines the relationship between various research dimensions as perceived, researched, and interpreted by academics and scholars. It involves text mining and content analysis to enable deeper, data-driven exploration of evolving themes and patterns within the AUT knowledge space. The MF is implemented through the case of the International Association for the Study of Traditional Environments (IASTE), which is identified based on its focus and longstanding contribution to the discourse since the late 1980s. The study demonstrates how the two pillars of IASTE–Traditional Dwellings and Settlements Review (TDSR) and the biennale conferences (recently annual conferences) have shaped the discourse on traditional environments. It primarily contributes to the field by advancing the application of the Metadata Framework (MF) as a systematic tool for mapping the evolution of AUT discourse, providing valuable insights for future research. Key findings reveal a significant rise in technological integration and governance studies, sustained interest in studying intangible cultural heritage, and growth in linking this with advanced technologies. Conclusions are drawn to elucidate evolving, emerging, and declining themes and areas within the overall knowledge space of architectural and urban traditions
The art of architecture wayfinding: navigating by objects, boundaries, and time
Get PDFThe purpose of this paper is to explore various forms of wayfinding through spatial reading. In particular, this article emphasizes how hidden clues play an important role in human movement and the wayfinding process. The purpose of this paper is to highlight hidden clues that are crucial to understanding architectural spatiality as a process of wayfinding. A film that contains a wayfinding narrative will be dismantled in this paper to explore various the arts of wayfinding. The selection of the films was based on the possibility of spatial reading, especially those that reflect the story of human movement and the wayfinding process. The analysis is based on observations of the film, particularly how spatial settings are compiled and used to wayfinding clues as the observed data. The data was collected by observing the actors about their wayfinding strategies. Using catalogs and diagrams, the results of the data were analyzed to obtain a spatial picture of wayfindings. Three aspects of hidden clues determine a person‘s wayfinding, namely objects, boundaries, and time. In terms of wayfinding, these three aspects may be considered outside of the physical form of architectural space. The results of the study contribute to the development of an architectural wayfinding system based on spatial narratives
Determinants of the sustainability of capability-based culinary businesses: evidence from urban areas in Central Java Province
Get PDFPurpose – Amidst the increasing public awareness of the need for environmentally friendly products and social concerns, sustainability practices can be utilized as a source of competitive advantage for businesses in the culinary industry. The purpose of this study is to investigate the effects of entrepreneurial marketing, transformation capability, and financial capability on sustainability.
Research methodology – This study was based on field survey data involving 315 culinary business actors in the cities of Semarang, Salatiga, and Surakarta, Central Java Province. The data analysis used the Partial Least Squares Structural Equation Modeling (PLS-SEM) method.
Findings – The determinants of sustainability predicted through the formulation of nine hypotheses are mostly proven empirically. Entrepreneurial marketing, transformation capability, and financial capability are demonstrated to have a positive effect on all dimensions of sustainability including economic, environmental, and social performance.
Research limitations – The objects of this research were limited to culinary business actors in urban areas so that only limited generalizations could be made. Future studies can be directed to involve business actors in rural areas so that they can capture the dynamics of sustainability practices better.
Practical implications – A policy that can be proposed based on research findings to the government in order to improve sustainability practices is to improve the capabilities of culinary business actors through training and mentoring that emphasize the importance of creating customer value, renewing company operations, and having financial literacy.
Originality/Value – This study fills the research gap by introducing a capability-based sustainability determinant model