VGTU Journals (Vilnius Gediminas Technical University - Vilnius Tech)
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A study on house price index performance: Mix adjustment and hierarchical linear growth repeat-sales models
No full textIn this study, we examined the differences between three house price indexes constructed using hedonic price, mix adjustment, and hierarchical linear growth repeat-sales modeling. The data consisted of housing sales across 13 administrative districts in Kaohsiung City from the third quarter of 2013 to 2022. The predictions were compared using the mean standard error, mean absolute percentage error, mean absolute error, and root-mean-square error. The results revealed that the hedonic price index performed the best; its prediction scores, as reflected by the four aforementioned metrics were 0.072, 1.176, 0.181, and 0.181, respectively. The index with the second best performance was the mix adjustment model, with scores of 0.154, 1.905, 0.293, and 0.293. The worst-performing index was the repeat-sales model, with scores of 0.309, 2.804, 0.439, and 0.439. After comparing the annual prediction errors of the three models, it became apparent that the hedonic price index had the best performance, followed by the mix adjustment index, and then the hierarchical linear growth repeat-sales index
Evaluation of the effect of fineness of fly ash in type I and type II Portland cement blended mortars
No full textThis study evaluates the effects of fineness-modified Class F fly ash (FA) on the performance of Type I and Type II Ordinary Portland Cement (OPC) mortars. FA was mechanically ground to achieve 90% (GFA1) and 98% (GFA2) passing through a 45-µm sieve, replacing OPC at 10%, 30%, and 50% by weight. Comprehensive testing included compressive strength, water demand, setting time, heat of hydration, acid resistance, and microstructural analysis. Results demonstrated that increasing FA fineness reduced water demand by up to 6.3% (Type I) and 5.9% (Type II) at 30% replacement, while enhancing long-term strength. Mortars with 10% GFA2 achieved 58.6 MPa at 56 days. Type II OPC blends exhibited superior acid resistance, with mass loss reductions of 43% (50% GFA2) compared to Type I, attributed to lower C₃A content and denser microstructures. Hydration heat decreased by 10.9% in Type II OPC, further reduced by 40% with 50% FA replacement. The microstructural analysis confirmed reduced ettringite formation and enhanced compactness in FA-modified mortars, correlating with improved durability. These findings highlight the viability of finely ground FA as a sustainable supplementary material, enabling highvolume FA utilization (up to 50%). The study provides critical insights for optimizing greener cement formulations, particularly in regions prioritizing Type II OPC for sulfate resistance and moderate heat applications, advancing Malaysia’s net-zero carbon goals through reduced clinker reliance
Multi-Criteria Decision Methods in the evaluation of social housing projects
No full textThe 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
Evaluating the integration of apartment building heating systems with low-temperature district heating networks
No full textAny renovation of apartment buildings by replacing or keeping their heating devices usually means that high temperatures of the heat carrier are maintained, which restricts boosting the efficiency of a central heating supply system. This also limits the scope for a switch to more efficient systems such as low-temperature district heating systems. To assess the impact of reducing the heat carrier temperature on indoor heating with a constant radiator area, the article investigates several alternatives alongside a base case scenario. In one scenario, the modernization of a building is examined, either by retaining the current heating devices or by substituting them with devices of equal size. Another scenario explores the modernization of a building by exchanging the heating devices and adjusting the building’s heating system to accommodate ultra-low temperatures. The possibility to reduce the temperature of the heat carrier in the heating system without any renovation of the building has been addressed as well. This led to seven alternatives. The analysis of the hourly data of the heating system model for two typical months in a heating season has revealed that when the building retains its existing area of heating devices post-renovation, the temperature can be brought down to 60/40/20 °C. It was also discovered that lowering the heat transfer temperature to ultra-low parameters (45/25/20 °C) cannot be achieved by refurbishing the buildings without increasing the number of radiators, as the heating devices will fail to deliver adequate heat for space heating.
Article in English.
Daugiabučių namų šildymo sistemų integravimo į žemos temperatūros centralizuoto šilumos tiekimo tinklus vertinimas
Santrauka
Daugiabučių namų renovacija, keičiant ar paliekant jų šildymo prietaisus, paprastai reiškia, kad reikia išlaikyti aukštą šilumnešio temperatūrą, o tai riboja centralizuoto šilumos tiekimo (CŠT) sistemos efektyvumo didinimą. Be to, tai apriboja galimybę pereiti prie efektyvesnių sistemų, pavyzdžiui, žematemperatūrių CŠT sistemų. Siekiant įvertinti sumažintos šilumnešio temperatūros poveikį patalpoms šildyti, kai radiatorių plotas išlieka pastovus, straipsnyje išnagrinėtos kelios alternatyvos ir bazinis scenarijus. Pagal vieną scenarijų nagrinėjamas pastato modernizavimas, paliekant esamus šildymo prietaisus arba pakeičiant juos tokio pat dydžio prietaisais. Pagal kitą scenarijų nagrinėjamas pastato modernizavimas pakeičiant šildymo prietaisus ir pritaikant pastato šildymo sistemą itin žemai temperatūrai. Taip pat nagrinėta galimybė sumažinti šilumnešio temperatūrą šildymo sistemoje neatnaujinant pastato. Tai leido parengti septynias alternatyvas. Išanalizavus šildymo sistemos modelio valandinius dviejų tipinių šildymo sezono mėnesių duomenis paaiškėjo, kad, po renovacijos pastate išlaikant esamą šildymo prietaisų plotą, temperatūrą galima sumažinti iki 60/40/20 °C. Taip pat nustatyta, kad renovuojant pastatus neįmanoma sumažinti šilumos perdavimo temperatūros iki itin žemų parametrų (45/25/20 °C) nekeičiant esamo radiatorių skaičiaus, nes šildymo prietaisai nesugebės tiekti pakankamai šilumos patalpoms šildyti.
Reikšminiai žodžiai: centralizuotas šilumos tiekimas (CŠT), pastatų modernizavimas, šildymo sistema, žema temperatūra
Overcoming barriers: the struggle for recognition of female successors in Indonesian family business
No full textFamily businesses are vital to Indonesia’s economy, making succession a critical process. However, female successors often face a “glass ceiling,” due to ingrained gender biases and traditional family roles, limiting their advancement into leadership roles within their family business. Recognising their unique identities can function as an alternative pathway to leadership, ensuring business continuity by challenging gender bias. This study aims to explore how recognition empowers female successors in Indonesia family business to overcome gender bias and pursue leaderships roles. Employing Interpretative Phenomenological Analysis (IPA), this study explored the lived experiences of nine female successors based on specific criteria. Data was gathered through semi-structured interviews. This research reveals that female successors face gender bias and credibility gap. To gain recognition, female successors actively imitate their fathers’ behaviour and building trust by fostering acceptance through dialogue. Drawing on Honneth’s recognition theory, female successors’ leadership transition is aided by verbal affirmation, paternal mentorship, legal adherence, and role appreciation. Future research should examine a larger sample and more diverse sample of female successors, tracking their experiences over a longer period, to provide a more comprehensive understanding of the challenges and opportunities they encounter within the unique context understand their evolving experiences in family business
Reverse logistics as a means of reducing the ecological footprint
No full textRapid technological development and related global challenges encourage the industrial sector to seek innovative solutions that would allow it to adapt to increasingly stringent environmental requirements and, at the same time, ensure the sustainability of its operations. Research shows that the industrial sector is experiencing the most significant impact due to growing requirements to reduce negative environmental impacts; therefore, the need to implement environmentally friendly processes is increasing. One of the most promising directions in this area is the integration of reverse logistics into the supply chains of industrial enterprises. Reverse logistics creates the prerequisites for reducing the ecological footprint, rational use of natural esources, reducing waste disposed of in landfills, and optimising energy costs. This article aims to analyse the possibilities of applying reverse logistics and its contribution to reducing the ecological footprint of different industrial sectors. The study is based on a systematic analysis of scientific literature and secondary data. The results of the study can be significant in shaping sustainable industrial policies and helping companies make strategic decisions related to the use of secondary raw materials, waste reduction and management of return product flows. The results of a Life Cycle Assessment (LCA) analysis comparing forward and reverse logistics processes showed that the application of reverse logistics has the potential to improve environmental performance. By modeling different situations, it was determined that reverse logistics is more efficient from an environmental point of view than traditional direct logistics.
Article in English.
Reversinė logistika kaip ekologinio pėdsako mažinimo priemonė
Santrauka
Sparti technologinė plėtra ir su ja susiję pasauliniai iššūkiai skatina pramonės sektorių ieškoti novatoriškų sprendimų, kurie padėtų prisitaikyti prie aukštų aplinkosaugos standartų ir užtikrinti veiklos tvarumą. Tyrimai rodo, kad aplinkosauginiai reikalavimai verčia pramonės sektorių pereiti prie tvaresnių procesų diegimo. Viena perspektyviausių krypčių šioje srityje yra reversinės logistikos integravimas į pramonės įmonių tiekimo grandines. Reversinė logistika sudaro prielaidas mažinti ekologinį pėdsaką, racionaliau naudoti gamtos išteklius, mažinti į sąvartynus patenkančių atliekų kiekį ir optimizuoti energijos sąnaudas. Šio tyrimo tikslas – išanalizuoti reversinės logistikos taikymo galimybes ir jos indėlį mažinant įvairių pramonės sektorių ekologinį pėdsaką. Tyrimas grindžiamas sistemine mokslinės literatūros ir antrinių duomenų analize. Gauti rezultatai gali būti reikšmingi formuojant tvarią pramonės politiką ir padedant įmonėms priimti strateginius sprendimus, susijusius su antrinių žaliavų naudojimu, atliekų mažinimu ir grįžtamųjų produktų srautų valdymu. Gyvavimo ciklo vertinimo (LCA) analizė, kurioje lyginami tiesioginės ir reversinės logistikos procesai, atskleidė, kad reversinės logistikos taikymas gali pagerinti aplinkosauginius rodiklius. Modeliuojant įvairius scenarijus nustatyta, kad reversinė logistika aplinkosauginiu požiūriu yra efektyvesnė nei tradicinė tiesioginė logistika.
Reikšminiai žodžiai: atvirkštinė logistika, ekologinis pėdsakas, situacijų modeliavimas, pramonė, gyvavimo ciklo analizė
Evaluation of strategic alternatives for corporate-group international expansion
No full textIn the mobility services sector, where economic, regulatory, technological, competitive and demand factors drive outcomes, rapid change creates a need for a clear, rational decision methodology. To ensure consistent international expansion, this study integrates strategic management and internationalization theory to design a criteria set for corporate-group market evaluation. The set is empirically validated in one mobility-services group using a panel of five senior managers who assessed three Central European markets—Poland, Czechia and Hungary. Criterion weights were obtained with AHP (pairwise comparisons on the Saaty 1–9 scale; consistency ratio CR ≤ 0.10) and alternatives were ranked using TOPSIS. Robustness was tested via sensitivity analysis by systematically varying weights ±10–20% and applying an equal-weights scenario; the ranking did not change. Based on the closeness coefficient, the results rank Czechia first (Ci = 0.626), Poland second (Ci = 0.595) and Hungary third (Ci = 0.306). The conclusions discuss portfolio implications for entry sequencing between short-term rental and long-term leasing models. The study contributes a sector-calibrated, literature-grounded and empirically validated criteria set, an AHP–TOPSIS application with real executive judgments and robustness checks, and a portfolio perspective that enables decisions for the whole corporate group rather than a single brand.
Article in Lithuanian.
Įmonių grupės tarptautinės plėtros strateginių alternatyvų vertinimas
Santrauka
Mobilumo paslaugų sektoriuje, kuriame sprendimus lemia ekonominiai, reguliaciniai, technologiniai, konkurenciniai ir paklausos / vartotojų elgsenos veiksniai, spartūs pokyčiai didina poreikį turėti aiškią metodiką sprendimams priimti. Dėl išorinių veiksnių spaudimo tampa būtina vadovautis racionaliu sprendimų priėmimu, kad tarptautinės plėtros sprendimai būtų pagrįsti ir nuoseklūs. Remiantis strateginio valdymo ir internacionalizacijos pagrindinėmis teorijomis, suformuojamas kriterijų rinkinys, skirtas priimti strateginiams įmonių grupės internacionalizacijos sprendimams, susijusiems su rinkų alternatyvų vertinimu. Rinkinys empiriškai patikrintas vienos mobilumo paslaugų įmonių grupės atveju, įtraukiant penkis ekspertus – atskirų toje grupėje veikiančių įmonių vadovus, kurie įvertino tris Centrinės Europos rinkas: Lenkiją, Čekiją ir Vengriją. Kriterijų svoriai nustatomi taikant AHP (poriniai palyginimai pagal Saaty 1–9; suderinamumo patikra, CR ≤ 0,10), o alternatyvių rinkų reitingas sudaromas TOPSIS metodu. Sprendimo stabilumui įvertinti atlikta jautrumo analizė – svoriai sistemiškai varijuoti ±10–20 % ir pritaikytas lygiaverčių svorių scenarijus; reitingo eiliškumas nepasikeitė. Rezultatai parodė, kad pagal artumo koeficientą pirmauja Čekija (Ci = 0,626), po jos – Lenkija (Ci = 0,595), trečia – Vengrija (Ci = 0,306). Išvadose aptariamos portfelio (trumpalaikės / ilgalaikės nuomos) implikacijos įėjimo sekai. Straipsnio indėlis pasireiškia sektoriui pritaikytu ir įmonių grupės (portfelio) specifiką atliepiančiu, literatūra grįstu, empiriškai validuotu kriterijų rinkiniu, AHP–TOPSIS taikymu su realių ekspertų vertinimais ir rezultatų tvirtumo patikra bei portfelio perspektyva, leidžiančia sprendimus priimti visai įmonių grupei, o ne tik atskiram prekės ženklui.
Reikšminiai žodžiai: strateginis valdymas, internacionalizacija, rinkos žinios, AHP, TOPSIS, mobilumo paslaugos, Centrinė Europa, portfelio perspektyva, įmonių grupė
Periodic travelling waves of a forced Cahn-Hilliard equation
No full textWe prove analytically the existence of a uniparametric family of periodic travelling waves for a Cahn-Hilliard equation with an external forcing term modelling the phase separation of a binary mixture of fluids with thermal diffusion. Some quantitative estimates on the solutions are derived
Dynamical analysis and adaptive synchronization of a new 6D hyperchaotic system with the cosine function
No full textThis paper presents a novel 6D dynamic system derived from modified second-type 3D Lorenz equations using state feed- back control. While these original 3D equations are structurally simpler than the classical Lorenz equations, they generate more topologically complex attractors with a distinctive two-winged butterfly structure. The proposed system is the most compact of its kind in the literature, containing only 11 terms: two cross-product nonlinearities, two piecewise linear functions, one cosine function, five linear terms, and one constant. The newly developed 6D hyper- chaotic system exhibits rich dynamic properties, including hidden attractors and dissipative behavior. A detailed dynamic analysis has identified two unstable hyperbolic equilibrium points, indicating the potential for self-exciting attractors. Additionally, bifurcation diagrams were constructed, Lyapunov exponents were computed, and the maximum Kaplan-Yorke dimension DKY = 3.23 was obtained at parameter value a = 0.5, revealing the high complexity of the hyperchaotic dynamics. Furthermore, multistability and offset boosting control were examined to gain deeper insights into the system’s behavior. Finally, synchronization between two identical 6D hyperchaotic systems was successfully achieved using an adaptive control method
Modelling solutions for cost optimization in multimodal transports considering the operational risk variables
No full textThe general risk assessment usually has the potential of setting a viable ground for pursuing a complex mathematical model based on an objective function, defined by several variables and constraints, which can be further applied for the specific analysis of multimodal transport. In order to assess the operational risks in multimodal transports, the authors have formulated an objective function with the aim of minimizes the sum of total cost of transportation on route components depending on the risk variables, respectively for road, maritime and railway subsystems of multimodal transport, in different combinatorial perspectives. The main objective of this study is to provide a method to value the overall risk assessment based on the defined objective function, considering both the variables that may influence the cost effectiveness and the relevant probabilities for each route component of multimodal transport. In this perspective, the authors have sought to provide practical solutions for decision-making process in multimodal routing, to optimize the costs on different routes and to contribute for decision-making process in routing and transports mode selection. The main contribution is residing from the novelty of decision-making process approach, considering the risk variables in different combination, facile to be applied professional in multimodal transportation in routing process, when risks are to be considered as significant for process reliability.
First published online 19 January 2026