Scientific Review Engineering and Environmental Sciences (SREES)

Life cycle cost analysis in investment projects – examination of case studies and risk mitigation with Monte Carlo simulation

Stefan Wieke — 2024-10-23

This work focuses on life cycle cost (LCC) analysis in the German natural gas infrastructure and recommends strategies to mitigate the uncertainties and risks involved using Monte Carlo simulation (MCS). It deals with the impact of input data and predicting the future development of input data on the results of the LCC analysis and discusses MCS for risk mitigation. Seven case studies for investments in Germany’s natural gas infrastructure are analyzed. In addition to the executed case studies, a case study from a scientific journal is included. The case studies were conducted between 2005 and 2015. Evaluation with real historical input data shows that the results of an LCC analysis depend on the reliability of input data and predictions on their development. The retrospective view shows that the best options are not always identified. Therefore, the results need to be validated using risk-mitigation methods, such as MCS. The executed case studies reflect the opinions of experts. This work shows how risk is mitigated through MCS while focusing on LCC analysis in the German natural gas infrastructure; however, the proposed risk mitigation with MCS can be adopted for other investment projects comprising capital expenditure (CAPEX) and operational expenditure (OPEX), for example, in construction, machines and other fields.

Evaluation of numerical modeling for the seismic response of an arch dam: the case of the Tichy-Haf Dam

El Houcine Ziadi — 2025-03-31

The seismic stability of concrete arch dams has always been a key parameter in seismic safety evaluation. For this purpose, this paper presents a numerical analysis of the seismic response of an arch of the Tichy-Haf Dam using the Midas GTS NX software. The study employs the finite element method and a nonlinear time history analysis to evaluate the stability of the structure. Several reference nodes on the dam body were selected to assess displacement, velocity, and acceleration during seismic events. To determine the values of these parameters, nonlinear time-history analyses were conducted using four accelerograms with amplitudes of 0.25 g, 0.32 g, 0.36 g, and 0.44 g, respectively. The dynamic numerical analysis revealed that the dam performed well during the seismic events, maintaining its structural integrity. The numerical model was validated by comparing the results from the static analysis with the actual monitoring data from the dam. This comparison demonstrated the effectiveness of the numerical simulation method in analyzing the stability of the arch dam.

Planning of green roofs for the best thermotechnical effect

Tetiana Tkachenko — 2025-03-31

The energy-efficient provision of indoor comfort for buildings is one of the most important requirements for modern construction. The greening of buildings is a natural measure to achieve this, for which the most limiting factor is the lack of systematic research on its positive effects. At the Kyiv National University of Construction and Architecture, a series of research on thermotechnical benefits and gas exchange in plant layers has been performed. The cooling effect of plants is up to 4 K. Semi-intensive green roofs on rooms have paths, which absorb solar radiation and load the air-conditioning systems. The proposed solution is to build the paths on the auxiliary premises with low microclimate requirements. The work aims to estimate the heat distribution in green roofs with paths to test the recommendation. Simulation using the Fourier–Kirchhoff equation shows that the path has a trace of higher heat transfer on the ceiling up to an additional 1.8‒2.0 W·m⁻². Thus, aligning the paths above the auxiliary premises is recommended, if possible. A better solution is to allow planting of the paths. Using plant-permit pavements and barefoot-in-dew systems such as ZinCo Soft Landscape are examples of such solutions. It is necessary to use grass that can be walked on.

Solidification/stabilization of fly ash contaminated with radiocesium into geopolymers

Šimon Rezbárik — 2025-03-31

The main goal of this work was to evaluate the possibilities of solidifying fly ashes contaminated with ¹³⁷Cs into geopolymer waste forms. In the first step, physico-chemical characterization of fly ash originating from the thermal power plant in Vojany (Slovak Republic) was carried out. Before the preparation of the geopolymer waste forms (ternary mixture Geocem, GEOFIX, s.r.o., Slovak Republic) containing fly ash at percentage weight proportions of 5%, 10%, 20%, and 40%, the fly ash was artificially contaminated with a ¹³⁷CsCl solution. The ¹³⁷Cs activity was measured by scintillation gamma-spectrometry. The leachability test conducted according to the American National Standard ANSI/ANS-16.1-1986 over five days showed that the geopolymer waste forms with fly ash contents of 5%, 10% and 20% met the required leachability index limits with values more than 6. The compressive strength test also confirmed that the samples with 40% ash content did not meet the required 5 MPa limit for their disposal as a radioactive waste.

Effect of soil nutrients on the stability of superabsorbent polymers as a tool for climate change mitigation

Lenka Vavrincová — 2025-03-31

The aim of this study was to assess the effect of soil nutrients on the stability of superabsorbent polymers (SAPs). In agriculture, SAPs are known to increase productivity in arid regions by improving plant water availability, optimizing root nutrient uptake, and increasing plant drought tolerance. In this study, we tested SAPs derived from starch and mixtures of acrylic acid and acrylamide. First, a physicochemical characterization of the SAPs was performed, which included optimizing the water absorption volume, determining the maximum absorption capacity, and analyzing the water binding kinetics. We then also investigated the effects of elements, such as Na, K, Zn and Cu, on the stability of SAPs. The results showed that the SAPs exhibited a high-water absorption capacity. However, reduced swelling capacity was observed in the presence of Hoagland’s medium and solutions of metal ions (Na, K, Zn, Cu) with equimolar concentrations to potassium in the SAP.

Enhancing urban water utilities: a case study of the Utility of the Future framework implementation in Indonesia

Yureana Wijayanti — 2025-03-31

Utility companies worldwide face unique challenges in innovation, inclusivity, market focus, and resilience. A uniform approach to action plans is impractical. The Utility of the Future (UoF) framework aims to guide companies in developing tailored action plans that reflect their specific areas of focus and long-term objectives. Therefore, the objective of this paper is to elaborate on the implementation of the UoF approach in reviewing the utility’s performance and in developing the 100-day action plans. The case study is a local government-owned enterprise of the water utility, Perumda Tirta Musi, in Palembang City, South Sumatra, Indonesia. The outcome is a 100-day action plan with short-term steps and a five-year plan with long-term actions. It shows that the UoF methodology can help water utilities understand their current condition and gaps from the current benchmark to their future goals, enabling inclusive action plans for world-class water utilities. Future studies will explore further UoF implementations in Indonesia to provide insights into sustainable performance improvement strategies.