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Found 6327 publications
Sustainability Aspects of Drone-Assisted Last-Mile Delivery Systems—A Discrete Event Simulation Approach
Publication Name: Energies
Publication Date: 2023-06-01
Volume: 16
Issue: 12
Page Range: Unknown
Description:
The goal of this article is to examine the advantages and disadvantages of the application of drones in last-mile delivery systems from a sustainability point of view regarding CO2 emissions and energy consumption. As commercial drones are developing rapidly, the application of such tools in the field of last-mile delivery and transportation can offer many opportunities to increase service flexibility, reduce delivery time and decrease CO2 emissions and energy consumption. In this article, a discrete event simulation is applied to examine how the assistance of drones in parcel delivery services can influence the sustainability aspects of such services regarding CO2 emissions and energy consumption in an urban environment. Based on factory parameters, a vehicle-based delivery scenario is compared to a drone-assisted scenario under ideal conditions. According to the results, within the simulation parameters with the assistance of drones, a decrease in CO2 emissions and energy consumption is possible in last-mile delivery services, but more environmental, technological and financial limitations should also be addressed and incorporated to determine whether such a development is worthwhile from a last-mile delivery company’s point of view.
Open Access: Yes
DOI: 10.3390/en16124656
The reaction of the metal and gold resource planning in the post-COVID-19 era and Russia-Ukrainian conflict: Role of fossil fuel markets for portfolio hedging strategies
Publication Name: Resources Policy
Publication Date: 2023-06-01
Volume: 83
Issue: Unknown
Page Range: Unknown
Description:
The prime objective of this article is to examine the policy-making role of metal markets, gold resources, and clean energy markets in the post-COVID-19 era and the Russia-Ukrainian military conflict. In doing so, we analyze the role of fossil fuels, clean energy, and metals markets, considering the military conflict in Ukraine in 2022. The study employs event study methodology (ESM), Total connectedness index (TCI), and network analyses. The results indicate that natural gas and clean energy prices are less affected by conflict in the aftermath of an invasion than traditional energy and metals markets. In addition, we observe an increase in the TCI in the energy markets during announcement days. The TCI of the metals market is greater than that of the energy market. According to network connectivity, the key asset class transmitters of the shock in Europe are the Geopolitical index (GPR), gold, and the clean energy stock index (ERIX). The U.S. markets are less affected by the situation in Ukraine. The average hedge suggests that the optimal hedge differs from one market to the next, with fossil fuels and renewable energy, respectively, being more hedge effective and reducing risk by an average of around 0.80 and 0.59, given their ability to function as a hedging instrument.
Open Access: Yes
Kriging-Assisted Multi-Objective Optimization Framework for Electric Motors Using Predetermined Driving Strategy
Publication Name: Energies
Publication Date: 2023-06-01
Volume: 16
Issue: 12
Page Range: Unknown
Description:
In this paper, a multi-objective optimization framework for electric motors and its validation is presented. This framework is suitable for the optimization of design variables of electric motors based on a predetermined driving strategy using MATLAB R2019b and Ansys Maxwell 2019 R3 software. The framework is capable of managing a wide range of objective functions due to its modular structure. The optimization can also be easily parallelized and enhanced with surrogate models to reduce the runtime. The framework is validated by manufacturing and measuring the optimized electric motor. The method’s applicability for solving electric motor design problems is demonstrated via the validation process. A test application is also presented, in which the operating points of a predetermined driving strategy provide the input for the optimization. The kriging surrogate model is used in the framework to reduce the runtime. The results of the optimization and the framework’s benefits and drawbacks are discussed through the provided examples, in addition to displaying the properly applicable design processes. The optimization framework provides a ready-to-use tool for optimizing electric motors based on the driving strategy for single- or multi-objective purposes. The applicability of the framework is demonstrated by optimizing the electric motor of a world recorder energy-efficient race vehicle. In this application, the optimization framework achieved a 2% improvement in energy consumption and a 9% increase in speed at a rated DC voltage, allowing the motor to operate at desired working points even with low battery voltage.
Open Access: Yes
DOI: 10.3390/en16124713
Seismic Vulnerability Assessment of an Unanchored Circular Storage Tank Against Elephant’s Foot Buckling
Publication Name: Journal of Vibration Engineering and Technologies
Publication Date: 2023-06-01
Volume: 11
Issue: 4
Page Range: 1661-1678
Description:
Purpose: Seismic vulnerability assessment of liquid containing storage tanks is the most vital relevance for industrial plants and society safety to endure damage during impending earthquakes. Because such systems also play an essential role in the public lifeline and also ensure continued use in emergencies. Furthermore, considering that the material contained in individual plants could be hazardous, requisite precautions have paramount importance against undesired leakage. The high internal pressure and axial forces exerted by the liquid in the steel tanks near the tank wall bottom produce elastic–plastic buckling, also known as Elephant’s Foot Buckling (EFB). As far as the authors are aware, no study has been carried out that involves a critical assessment and comparison of IDA and truncated IDA-based EFB failure criterion. This study provides insight into incremental dynamic analysis (IDA) and truncated IDA-based seismic evaluation of cylindrical unanchored steel storage tanks by employing a developed pressure-based surrogate modeling approach. For this purpose, probability-based seismic assessment of a representative sample is considered based on IDA and truncated IDA approaches to identify the potential of the EFB failure and to explore potential enhancements in the sophisticated structural analysis model to prevent the hazardous effects of impending earthquakes. Methods: Due to the significance of industrial plants for public safety and benefit, the structural response evaluation methods for different types of storage tanks have been widely reported. In the literature, the most comprehensive analytical assessment methodology is the IDA approach, in which nonlinear time-history analyses are considered in the finite element analysis model to assess the structural model’s seismic performance. Results: To generate fragility curves, both IDA approaches are employed, taking into consideration and ignoring uncertainty of material properties. The values of the two methods-based fragility curves approach each other as the magnitude of dispersion increases. Conclusion: The two fragility curves give the probability of failures close to each other as the dispersion amount increases while considering the uncertainty of the material properties. In addition, fragility curves generated based on the truncated IDA have been found to give a higher probability of failure, up to 32.5 percent. When compared to the IDA-based fragility curves, the truncated IDA-based fragility curves were found to be on the conservative side.
Open Access: Yes
The Dynamic Properties of Sand under Torsion: A Literature Review
Publication Name: Geotechnics
Publication Date: 2023-06-01
Volume: 3
Issue: 2
Page Range: 480-514
Description:
Resonant column (RC) and the torsional simple shear (TOSS) tests have shown proven competency in acquiring precise and repeatable measurements regarding the shear modulus and damping ratio of soil. For most dynamic geotechnical problems, the shear modulus represents the stiffness of the soil, while the damping ratio describes energy dissipation. Many studies in the last few decades focused on developing the relevant equipment and investigating the effect of different soil properties on the dynamic behavior of soil. Researchers have introduced correlations to approximate this behavior without conducting dynamic torsional testing. Soil models (e.g., Ramberg-Osgood and Hardin-Drnevich) can simulate shear stress-strain curves after finding the curve-fitting parameters. Due to the complexity of dynamic behavior and its dependency on various factors in soils, the RO and HD equations help model the behavior more simply. This paper presents a literature review and evaluation of the studies, correlations, soil models, and parameters affecting the dynamic behavior of dry sand under torsion.
Open Access: Yes
Skid Resistance of Asphalt Pavements
Publication Name: Eng
Publication Date: 2023-06-01
Volume: 4
Issue: 2
Page Range: 1597-1615
Description:
Skid resistance of a road pavement surface is the force developed when a tyre is prevented from rotating and slides along the pavement surface. This property comes from the combination of the macro- and micro-texture of pavement. The skid resistance of an asphalt pavement is an important parameter influencing driving safety on a road since there is a proven relationship between skid resistance and accident parameters. This paper deals with the measurement principle of pavement skid resistance (surface friction) including longitudinal and transverse friction. A high number of measuring devices of skid resistance are also introduced, highlighting their advantages and limitations. Moreover, the measurement policies in the European Union and in Hungary are outlined. Pavement surface texture is investigated, dealing with the levels of surface texture, the most common measuring techniques, the macro-texture features of asphalt types, as well as the Hungarian regulation in the field. As a related topic, the aggregate properties and their implication in the relevant Hungarian specification are introduced briefly as well. Some outcomes of the EU’s COST Action 354 on the development of unified European macro-roughness and skid resistance performance indicators and indices are also presented.
Open Access: Yes
DOI: 10.3390/eng4020091
Perceived university support and environment as a factor of entrepreneurial intention: Evidence from Western Transdanubia Region
Publication Name: Plos One
Publication Date: 2023-06-01
Volume: 18
Issue: 6 June
Page Range: Unknown
Description:
The exploration of entrepreneurship has become a priority for scientific research in recent years. Understanding this phenomenon is particularly important for the transformation of entrepreneurship into action, which is a key factor in early-stage entrepreneurial activity. This gains particular relevance in the university environment, where, in addition to the conventional teaching and research functions, the entrepreneurial university operation based on open innovation, as well as the enhancement of entrepreneurial attitudes of researchers and students, are receiving increased attention. This study is based on a survey conducted among students attending a Hungarian university of applied science in Western Transdanubia Region who have demonstrated their existing entrepreneurial commitment by joining a national startup training and incubation programme. The main research question of the study is to what extent student entrepreneurship intention is influenced by the environment of the entrepreneurial university ecosystem and the support services available at the university. A further question is whether these factors are able to mitigate the negative effects of internal cognitive and external barriers by enhancing entrepreneurial attitudes and perceived behavioural control. The relatively large number of students involved in the programme allows the data to be analysed using SEM modelling. The results indicate a strong covariance between the perceived university support and environment among students. Another observation is the distinct effect of these institutional factors on perceived behavioural control of students.
Open Access: Yes
Entrepreneurial ecosystem and urban innovation: Contextual findings in the lens of sustainable development from China
Publication Name: Technological Forecasting and Social Change
Publication Date: 2023-06-01
Volume: 191
Issue: Unknown
Page Range: Unknown
Description:
Entrepreneurial activities constitute a critical antecedent to urban innovation (UI), which reflects the levels of innovation and creation activities in cities and is strongly related to their economic development. Existing research on UI focuses on the net effects of individual explanatories in isolation while leaving the synergistic effects between these factors under-examined. Drawing from the entrepreneurial ecosystem (EE) theory, we constructed an entrepreneurial ecosystem composed of market, finance, human capital, internet access, transportation, and government, adopting the fuzzy set qualitative comparative analysis (fsQCA) of 34 representative cities in China to analyze the combined effects of multiple elements underpinned UI. Consequently, the following findings were observed. First, no single entrepreneurial ecosystem element constitutes a necessary condition for a high UI level. Second, large markets and well-designed government services correspond well to high UI levels. Third, the lack of mature transportation and a large market lead to a non-high level. This study advances antecedent research on UI by addressing the complex mechanism of multi-factor linkages.
Open Access: Yes
Effect of Path QoS on Throughput Aggregation Capability of the MPT Network Layer Multipath Communication Library
Publication Name: Infocommunications Journal
Publication Date: 2023-06-01
Volume: 15
Issue: 2
Page Range: 14-20
Description:
An increase in the use of smart and portable devices like smartphones, laptops, and tablets has led to a rise in the number of network interfaces and thus the number of possible channels for communication. However, the current approach over the Internet only employs a single path for a communication session. As an innovative and promising method for real-time transmission based on GRE-in-UDP encapsulation, which provides an IPv4 or IPv6 tunneling mechanism, this paper presents multipath throughput testing for the MPT network layer multipath communication library. We investigated the effectiveness of MPT's channel capacity aggregation while dealing with wired channels and examined scenarios in symmetric and asymmetric paths. Our network throughput measurements showed that MPT can efficiently aggregate the capacities of both symmetric and asymmetric paths. In this paper, we established a network topology that included a server, which we used for generating various quality of service (QoS) metrics. We measured how latency, transmission speed, packet loss rate, jitter, and the setting of the path weights influence throughput aggregation capability of the MPT communication library.
Open Access: Yes
