VGTU Journals (Vilnius Gediminas Technical University - Vilnius Tech)
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Discrete Gronwall’s inequality for Ulam stability of delay fractional difference equations
No full textThis paper investigates Ulam stability of delay fractional difference equations. First, a useful equality of double fractional sums is employed and discrete Gronwall’s inequality of delay type is provided. A delay discrete-time Mittag-Leffler function is used and its non-negativity condition is given. With the solutions’ existences, Ulam stability condition is presented to discuss the error estimation of exact and approximate solutions
Discrete universality theorem for Matsumoto zeta-functions and nontrivial zeros of the Riemann zeta-function
No full textIn 2017, Garunkštis, Laurinčikas and Macaitienė proved the discrete universality theorem for the Riemann zeta-function shifted by imaginary parts of nontrivial zeros of the Riemann zeta-function. This discrete universality has been extended to various zeta-functions and L-functions. In this paper, we generalize this discrete universality for Matsumoto zeta-functions
A priori estimate and existence of solutions with symmetric derivatives for a third-order two-point boundary value problem
No full textWe study a priori estimate, existence, and uniqueness of solutions with symmetric derivatives for a third-order boundary value problem. The main tool in the proof of our existence result is Leray-Schauder continuation principle. Two examples are included to illustrate the applicability of the results
Some properties of solutions of α-conformable differential equations with piecewise constant arguments: existence and uniqueness, asymptotic stability, oscillation and periodicity
No full textConformable differential equations, based on the recently introduced conformable derivative, represent a novel and increasingly popular class of differential equations. This framework offers significant advantages over traditional models, particularly due to its simplicity and enhanced flexibility in modeling diverse phenomena. In this paper, we examine conformable differential equations with piecewise constant arguments. We establish the existence and uniqueness of solutions for these equations and derive conditions for oscillatory behavior, convergence, and periodicity. Additionally, we provide numerical examples to support and illustrate the theoretical results
Analyzing Helmholtz phenomena for mixed boundary values via graphically controlled contractions
No full textHelmholtz’s problem helps us to completely understand how sound behaves in a cylinder that is closed from one of its ends and opened at another. This paper aims to employ some novel convergence results to the Helmholtz problem with mixed boundary conditions and demonstrate the existence and uniqueness of the solution by applying graph-controlled contractions. For this purpose, we enunciate graphically Reich type and graphically Ćirić type contractions in the realm of graphical-controlled metric type spaces. In our study, we showcase the existence and uniqueness of fixed point results by employing these graphical contractions. This is demonstrated through extensive examples that a graphicalcontrolled metric-type space is distinct from traditional controlled metric-type spaces. We also exhibit an example of a graphically Reich contraction that is not a classical Reich contraction. Similarly, a decent example of graphical Ćirić contraction is presented, which is distinct from the classical Ćirić contraction. Concrete illustrative examples solidify our theoretical framework
Data-based flight optimization model for scheduling: noise management approach
No full textCivil aviation noise remains a key challenge that limits the industry’s growth. With the rise in global air traffic, aviation noise pollution is becoming an increasingly pressing concern. This research develops a data-driven flight optimization model to mitigate noise levels at Vilnius Airport. The research is conducted in three stages: first, existing noise reduction strategies and the potential of scheduling optimization tools are reviewed. Next, EUROCONTROL’s integrated aircraft noise and emissions modelling platform is used to assess noise levels for each flight operation under relevant atmospheric conditions. Finally, a flight schedule optimization model is developed by considering key variables, constraints, and assumptions affecting airport noise, followed by an evaluation of its performance and efficiency. The findings suggest that effective noise management requires a comprehensive approach, integrating operational adjustments with a detailed understanding of industry factors
Above-building parking area and urban plan arrangement proposal for civil aircraft: the case of Türkiye
No full textThis study examines the feasibility of integrating vertical take-off and landing (VTOL) civil aircraft into urban environments in Türkiye, with a focus on adapting existing building structures and urban planning regulations. The research investigates the structural, legislative, and urban design modifications needed to support the safe operation of personal and family-use VTOL vehicles. Case studies from Istanbul, Ankara, Izmir, Diyarbakır, and Samsun highlight the challenges and opportunities posed by both old, unplanned urban areas and newer, systematically developed regions. The findings reveal the need for significant legal reforms, including updates to civil aviation regulations, and structural adjustments such as rooftop reinforcements to support VTOL operations. The study emphasizes that incorporating aircraft-friendly infrastructure in new urban developments is more cost-effective than retrofitting existing buildings. It also highlights the importance of creating dedicated take-off, landing, and parking areas within urban spaces to accommodate the growing demand for urban air mobility. The research concludes that proactive urban planning, legislative changes, and technological innovation are critical for fostering sustainable urban air mobility, enhancing transportation efficiency, and ensuring safety in Türkiye’s evolving urban landscapes
How does FinTech development drive corporate innovation? Fresh evidence from the perspective of financial supply
No full textBy constructing a city-level financial-technology (FinTech) development dataset, this study examines the impact of FinTech on corporate-innovation behavior from a financial-supply perspective. The results reveal that FinTech promotes corporate innovation by reducing corporate-financing constraints and financing costs, alleviating information asymmetry, and expanding financing channels. This promotion effect is more pronounced for private, small, and young firms, firms with fewer fixed assets, and those located in low-regulation intensity areas. Moreover, credit-based FinTech companies have a greater impact on business innovation. In addition, bank deregulation and increased bank competition crowd out the financial supply of FinTech for innovation financing. Knowledge of these impacts can help corporate managers, governments, and financial regulators to formulate more effective development strategies to promote corporate innovation.
First published online 15 November 202
Market time-series reversal: evidence from China’s market
No full textUpon high-frequency data of China Securities Index 300 (CSI 300) exchange-traded fund and index future contracts, we demonstrate a time-series reversal pattern between the last three-hour returns on current day and those on previous day. Further this reversal is also found in China index future market. This predictability has been illustrated to be both statistically and economically significant, and the significance is stronger on more volatile/higher volume days and non-bearish market state. Extensive regression analysis suggests that the time-series reversal is mainly induced by irrational investor overreaction, not by the lack of liquidity provision. Moreover, the economic value of the reversal pattern is evaluated to yield an outstanding trading performance by executing a market timing strategy.
First published online 02 April 202
Will the use of cashless subsidy potentially reduce illegal underground economy activity? A case study in Indonesia
No full textPurpose – This study was conducted to understand the potential of cashless subsidy to reduce illegal underground economy activity in Indonesia.
Research methodology – The research was done through a qualitative approach then analyzed based on the content analysis and sentiment analysis using Digital Public Services Index frim Digital Economy and Society Index (DESI) research methodology as base. The data used on this study are Indonesia e-news on kompas.com, detik.com, and tempo.co from March 2021- 2022 using two keywords “subsidi” (subsidy), “non-tunai” (cashless) and “nirsentuh” (contactless).
Findings – The result of this study shows illegal underground economy activity can be reduced by implementing cashless subsidy policy.
Research limitations – The data used on the research were big data obtained from e-news be- cause the lack primary reliable respondent. We could not estimate the cashless subsidy after COVID-19 was ended in Indonesia because the declaration of the end of COVID-19 pandemic in Indonesia was on 29 June 2023.
Practical implications – This study also provides two recommendations for those problems: (a) increase digital financial literacy awareness; (b) improve the formal economy activity.
Originality/Value – There still no specific research of cashless subsidy and their practice in shad- ow economy perspective, especially in developing countries such as Indonesia.