The aim of the research is to identify and quantify the direct economic effects resulting from the improved seaport nautical access and capacity expansion. This case study considers a regional port located in the Baltic sea and relates to port users, i.e., shipping operators and shippers. The effects were identified for maritime transport by comparing transport performance in two scenarios: with-the-investment and without-the-investment. Incremental calculus addresses freights (containers, dry bulk, and cereals) traded to and from the given port, changes in size of vessels, and the shipping route alternatives vis-a-vis adjacent ports in the range. Sustainable impact concerns generalized maritime transport cost, i.e., shipping operating costs and port-to-port transit time, as well as energy consumption and external costs of maritime shipping. To capture effects, daily and unit dry bulk, as well as container shipping cost, values of time, and marginal external costs were revealed in frei... [more]

The maximum entropy bootstrap for time series is applied in this study to investigate the nexus between carbon emissions from electricity generation and the gross domestic product, using a bivariate framework for eight Middle Eastern countries between 1995 and 2017. The sample under study includes oil-producing countries such as Bahrain, Iran, Iraq, Kuwait, Oman, Qatar, Saudi Arabia, and United Arab Emirates. As the electricity generation in these economies relies mainly on oil and gas, finding out the existence and direction of the relationship between the two considered variables has remarkable implications for policymakers and governments in these countries to achieve both higher economic growth and environmental protection. As expected, this nexus is validated for all countries in the sample but not in all models, time periods, and lags. Therefore, policymakers can set appropriate electricity conservation policies based on these varied empirical findings to boost economic growth wi... [more]

In recent years, the use of electric Autonomous Wheeled Mobile Robots (AWMRs) has dramatically increased in transport of the production chain. Generally, AWMRs must operate for several hours on a single battery charge. Since the energy density of the battery is limited, energy efficiency becomes a key element in improving material transportation performance during the manufacturing process. However, energy consumption is influenced by the navigation stages, because the type of motion necessary for the AWMR to perform during a mission is totally defined by these stages. Therefore, this paper analyzes methods of energy efficiency that have been studied recently for AWMR navigation stages. The selected publications are classified into planning and motion control categories in order to identify research gaps. Unlike other similar studies, this work focuses on these methods with respect to their implications for the energy consumption of AWMRs. In addition, by using an industrial Self-Guide... [more]

As an excellent heat spreader candidate, graphene attracts considerable interest concerning its application in concentrated photovoltaic (CPV) systems. The consequences of employing a graphene-coated neutral density (GCND) filter to mitigate concentrated light impact adequately. Hence, the temperature for a concentrated photovoltaic system is reported in this work. A systematic thermal characterisation study was carried out using three different thickness-based GCND filters. Interestingly, using the GCND filter, the focal spot temperature remained considerably lower than that of the incident temperature for a more extended period. The graphene coating orientation further influenced the temperature gradient behaviour of the focal spot and incident temperature. The thermal and electrical results depended on the GC samples’ thickness and emplacement, leading to dramatic differences in their respective photovoltaic performance. As a base substrate of the GCND filter, the low-iron glass suf... [more]

The adoption of electric buses in public transport requires careful planning for the bus fleet and charging infrastructure. A mathematical model of an urban bus service was developed to support the deployment of charging infrastructure. The novelty of the model is that it incorporates infrastructure elements for both static and dynamic charging technologies at the same time. The model supports the electrification of the bus lines without route and schedule adjustments. The volume of charged energy at charging units is considered as a variable in the objective function to determine the location of charging units at minimum cost. The model was verified by a case study based on actual bus service data. It was found that the use of static chargers is more favorable if the cost of a static charging unit is less than the cost of a dynamic charger with a length of 1600 m and the charging power of static chargers is three times greater than the charging power of dynamic chargers. The relations... [more]

The paper proposes a new technology for fluid production intensification, in particular hydrocarbons, which is implemented via significant increasing of the local wellbore diameter in the interval, where the productive stratum is present. The proposed technology improves the well productivity by increasing the filtration surface area and opening new channels for filtering fluids into the well. The innovative, technical idea is to drill large diameter circular recesses in planes perpendicular to the well axis. After that, the rock mass located between the circular recesses are destroyed by applying static or dynamic axial loads. The required value of the axial force is provided by the weight of the standard drilling tool. As a result of the study, the analytical relations to specify the admissible radius of circular recesses and admissible thickness of rock mass between two adjacent circular recesses from the condition of safe operation are obtained. The numerical analysis carried out f... [more]

Occupant behavior can significantly influence the operation and performance of buildings. Many occupant-centric key performance indicators (KPIs) rely on having accurate counts of the number of occupants in a building, which is very different to how occupancy information is currently collected in the majority of buildings today. To address this gap, the authors develop a standardized methodology for the calculation of percent space utilization for buildings, which is formulated with respect to two prevalent operational data schemas: the Brick Schema and Project Haystack. The methodology is scalable across different levels of spatial granularity and irrespective of sensor placement. Moreover, the methods are intended to make use of typical occupancy sensors that capture presence level occupancy and not counts of people. Since occupant-hours is a preferable metric to use in KPI calculations, a method to convert between percent space utilization and occupant-hours using the design occupan... [more]

This work focused on a compound PV/T waste heat driven ejector-heat pump system for simultaneous data centre cooling and waste heat recovery for district heating. The system uses PV/T waste heat as the generator’s heat source, acting with the vapour generated in an evaporative condenser as the ejector drive force. Conventional and advanced exergy and advanced exergoeconomic analyses are used to determine the cause and avoidable degree of the components’ exergy destruction rate and cost rates. Regarding the conventional exergy analysis for the whole system, the compressor represents the largest exergy destruction source of 26%. On the other hand, the generator shows the lowest sources (2%). The advanced exergy analysis indicates that 59.4% of the whole system thermodynamical inefficiencies can be avoided by further design optimisation. The compressor has the highest contribution to the destruction in the avoidable exergy destruction rate (21%), followed by the ejector (18%) and condense... [more]

In the last several years, the coordination control of hybrid AC/DC microgrids (HMGs) has been gaining increasingly more attention. However, most of these discussions are focused on single-bus HMGs whose AC or DC bus is not sectionalized by AC or DC breakers. Compared with these single-bus HMGs, the bus-sectionalized HMG has more flexible topologies, more diverse operation modes, and consequently higher service reliability. However, meanwhile, these benefits also bring challenges to the stable operation of bus-sectionalized HMGs, particularly for mode switching. Relying on the national HMG demonstrative project in Shaoxing, China, this paper makes efforts to present the hierarchical control paradigm of a typical bus-sectionalized HMG toward standardization. The test results demonstrate that the proposed system provides seamless switching and uninterrupted power supply without controller reconfiguration among different operation modes. The operational data are also brought forth and ana... [more]

A diamond’s color grading is a dominant property that determines its market value. Its color quality is dependent on the light transmittance through the diamond and is largely influenced by nitrogen contamination, which induces a yellow/brown tint within the diamond, as well as by structural defects in the crystal (in rare cases boron contamination results in a blue tint). Generally, spectroscopic instrumentation (in the infrared or UV−visible spectral range) is used in industry to measure polished and rough diamonds, but the results are not accurate enough for precise determination of color grade. Thus, new methods should be developed to determine the color grade of diamonds at longer wavelengths, such as microwave (MV). No difference exists between rough and polished diamonds regarding stray light when the MW frequency is used. Thus, several waveguides that cover a frequency range of 3.95−26.5 GHz, as well as suitable resonator mirrors, have been developed using transmission/reflecti... [more]

In view of potential uses in short-term thermochemical heat storage by sorption of water vapor, the capacity to release a sufficient heat amount at the appropriate rate of a Prussian blue analogue (PBA) containing hexacyanocobaltate vacancies has been compared with those of 13X type zeolites possessing Na+, Ce3+, Ce4+, or Tb3+ extra-framework compensating cations. The extended structural and surface characterization demonstrated good reproducibility of the preparation procedures performed on a 10-g scale. The adsorbents were tested under dynamic conditions of gas flow with the aid of either a gas flow calorimeter (120 mL h−1 helium flow) to measure the amount and rate of the integral heat release or a laboratory-scale test rig (15,000 to 22,800 mL h−1 nitrogen flow) to monitor the outlet temperature of nitrogen heated by adsorption. For a regeneration temperature of 353 K and a partial H2O pressure of 2.8 kPa in helium, the PBA sample yielded an integral heat ranging between 900 and 10... [more]

Small possible hydrocarbon gas reservoirs were analysed in the Bjelovar Subdepression in Northern Croatia. This area includes the Neogene−Quaternary, mostly clastics, sequences, reaching 3000+ metres in the deepest part. The shallow south-eastern part of the Drava Depression contains a subdepression characterised with several, mostly small, discovered hydrocarbon fields, where the majority are located on the northern subdepression margin. The reason is the large distance from the main depressional migration pathways and main, deep, mature source rock depocenters. However, two promising unconventional targets were discovered inside the subdepression and both were proven by drilling. The first are source rocks of Badenian, of kerogen type III in early catagenesis, where partially inefficient expulsion probably kept significant gas volumes trapped in the source rock during primary migration. Such structures are the Western Bjelovar (or Rovišće) and the Eastern Bjelovar (or Velika Ciglena)... [more]

Charging of electric vehicles (EVs) on a large scale can cause problems for the grid. Utilizing local flexibility resources, such as smart charging, stationary battery, vehicle-to-grid applications, and local generation can be an efficient way to contain the grid challenges and mitigate the need for grid reinforcement. Focusing on the INSPIRIA charging station located in Norway, this paper investigates the possibility of coping with imminent grid challenges by means of local flexibility. First, the potential grid challenges are estimated with the help of Monte Carlo simulations. Second, cost and performance for the various local flexibility sources are presented. Third, an analysis of the choice of battery, charging process, and battery economy are provided. Finally, the paper discusses the optimal mix of flexibility resources to efficiently mitigate grid challenges at the INSPIRIA charging station.

The increase in global air temperature is well documented, as during the last several years each decade has been consecutively warmer than the preceding. As climatic conditions affect the energy performance of buildings, the changes in outdoor air temperature and humidity will inevitably lead to significant alterations in energy consumption and costs for the heating, ventilating and air conditioning (HVAC) of buildings. The availability and quality of climatic data play an important role in the accuracy of energy analysis results. In this study, the hourly temperature and relative humidity of outdoor air measurements, for a period of three decades (1983−2012), recorded at the climatic station of the National Observatory of Athens were processed, and an up-to-date set of specific data for the application of bin methods was produced and presented. The data were then used to calculate changes in the energy demands in a typical office building throughout the specified period. Results showe... [more]

Fuel consumption and emissions in parallel hybrid electric vehicles (HEVs) are directly linked to the way the load request to the wheels is managed between the internal combustion engine and the electric motor powered by the battery. A significant reduction in both consumption and emissions can be achieved by optimally controlling the power split on an entire driving mission (full horizon—FH). However, the entire driving path is often not predictable in real applications, hindering the fulfillment of the advantages gained through such an approach. An improvement can be achieved by exploiting more information available onboard, such as those derived from Advanced Driver Assistance Systems (ADAS) and vehicle connectivity (V2X). With this aim, the present work presents the design and verification, in a simulated environment, of an optimized controller for HEVs energy management, based on dynamic programming (DP) and receding horizon (RH) approaches. The control algorithm entails the parti... [more]

Oscillating water column (OWC) systems are water power generation plants that transform wave kinetic energy into electrical energy by a surrounded air column in a chamber that changes its pressure through the waves motion. The chamber pressure output spins a Wells turbine that is linked to a doubly fed induction generator (DFIG), flexible devices that adjust the turbine speed to increase the efficiency. However, there are different nonlinearities associated with these systems such as weather conditions, uncertainties, and turbine stalling phenomenon. In this research, a fuzzy logic controller (FLC) combined with an airflow reference generator (ARG) was designed and validated in a simulation environment to display the efficiency enhancement of an OWC system by the regulation of the turbine speed. Results show that the proposed framework not only increased the system output power, but the stalling is also avoided under different pressure profiles.

The aim of the study was to analyze emissions in the supply chain and to identify, based on a literature analysis, which supply chain strategies could contribute to reducing these emissions. A broad spectrum of new supply chain strategy solutions was identified and, based on simulations of selected products, conclusions were drawn and the advantages and disadvantages of theoretical solutions were presented for individual cases. A critical analysis of the literature and simulation methods were used to illustrate the problem presented in this paper, to identify the factors causing greenhouse gas emissions and to draw conclusions in the form of proposals to redesign existing strategies, considering the factors determining the increase in pollution caused by the performed logistics processes. The results of the simulations and the literature analysis indicate that solutions related to the redesign of strategies must consider the specificity of the product and the nature of the chain. Not a... [more]

Decades of wind turbine research, development and installation have demonstrated reductions in levelized cost of energy (LCOE) resulting from turbines with larger rotor diameters and increased hub heights. Further reductions in LCOE by up-scaling turbine size can be challenged by practical limitations such as the square-cube law: where the power scales with the square of the blade length and the added mass scales with the volume (the cube). Active blade load control can disrupt this trend, allowing longer blades with less mass. This paper presents the details of the development of a robust load control system to reduce blade fatigue loads. The control system, which we coined sectional lift control or SLC, uses a lift actuator model to emulate an active flow control device. The main contributions of this paper are: (1) Methodology for SLC design to reduce dynamic blade root moments in a neighborhood of the rotor angular frequency (1P). (2) Analysis and numerical evidence supporting the... [more]

Large scale offshore wind farms are relatively new infrastructures and are being deployed in regions prone to earthquakes. Offshore wind farms comprise of both offshore wind turbines (OWTs) and balance of plants (BOP) facilities, such as inter-array and export cables, grid connection etc. An OWT structure can be either grounded systems (rigidly anchored to the seabed) or floating systems (with tension legs or catenary cables). OWTs are dynamically-sensitive structures made of a long slender tower with a top-heavy mass, known as Nacelle, to which a heavy rotating mass (hub and blades) is attached. These structures, apart from the variable environmental wind and wave loads, may also be subjected to earthquake related hazards in seismic zones. The earthquake hazards that can affect offshore wind farm are fault displacement, seismic shaking, subsurface liquefaction, submarine landslides, tsunami effects and a combination thereof. Procedures for seismic designing OWTs are not explicitly men... [more]

China’s Belt and Road Initiative (BRI) will inevitably affect global energy cooperation. Along the Belt and Road, there are many developing countries. To understand the energy cooperation and development of these countries comprehensively is of great significance to guide their development and evaluate the impact of the BRI on the world energy and economic pattern. However, there is insufficient attention on those countries. Based on embodied energy analysis, a method which can track direct and indirect energy consumption in the economic system, effectively linking energy with the economy and environment, this paper proposes an evolution model of the embodied energy flow of the countries. Then, it simulates the evolution of the embodied energy flow under different cooperation strategies. The results show that if cooperation between countries positively affects their cooperation with other countries, adopting a mixed strategy is an advisable choice. On the contrary, cooperation with “po... [more]

A comprehensive assessment of smart grids is critical for their development. Existing scientific research testifies to the urgency and complexity of the problem of implementing smart grids effectively, both in terms of a single project performance and from the standpoint of creating a local, and later global, energy system. The multidimensionality of smart grids makes it challenging to assess the effectiveness of their implementation. Difficulties in evaluation arise because it is challenging to consider technical, technological, economic, and other relevant aspects of smart grids’ development within a single evaluation system. There are currently a significant number of smart grid assessment systems. However, it remains debatable how systematically and comprehensively they measure the efficiency of a smart grid. This, in turn, raises the question of whether there is a universal evaluation system that integrally considers all the crucial components of smart grids and is suitable for ev... [more]

The concept of hybrid wind power plants (HWPPs) that consist of wind, solar and batteries has received a lot of attention, since HWPPs provide a number of advantages thanks to the complementary nature of wind and solar energy and the flexibility of batteries. Nevertheless, converter-based technologies, as interfaces of HWPPs to the utility grid, contribute to the reduction of total system inertia, making the system more volatile and creating additional threats to frequency stability. To address these operational challenges, the capability of supercapacitors (SCs) to provide fast frequency reserve (FFR) is explored in this paper to enhance the frequency response of the HWPP. Two topologies for integrating SCs into the HWPP are proposed: (1) connecting SC to the DC link of wind turbine (WT) via a DC-DC converter interface, (2) directly connecting SC to the DC link of WT without converter interface. Frequency controllers at the asset level are proposed for these two topologies accordingly... [more]

Electricity Distributions Networks (DNs) are changing from a once passive to an active electric power system element. This change, driven by several European Commission Directives and Regulations in the energy sector prompts the proliferated integration of new network elements, which can actively participate in network operations if adequately utilized. This paper addresses the possibility of using these active DN elements for optimization of a time-discrete network operation in terms of minimization of power losses while ensuring other operational constraints (i.e., voltage profiles and line currents). The active elements considered within the proposed optimization procedure are distributed generation units, capable of reactive power provision; remotely controlled switches for changing the network configuration; and an on-load tap changer-equipped substation, supplying the network. The proposed procedure was tested on a model of an actual medium voltage DN. The results showed that sim... [more]

Designed to store and discharge electrical energy, rechargeable batteries consist of elementary storage cell assemblies. Aging is affected by various aggravating factors, mainly temperature. There are many electric or electrochemical models which describe their operation. Most standard models do not consider the aging phenomena of batteries and their consequences, while batteries deteriorate when used or stored. Precisely, most battery models do not simulate the influence of cell aging on other cells. The model presented in this paper incorporates aging and the effects of mutual interactions between cells. The model can be established based on four measurement points on the cell characteristic curve and allows the simulation of a single cell’s or multiple coupled cells’ behavior. The model can then be easily implemented in simulation software like Matlab.

This paper addresses the implementation and optimization of an Extended Kalman Filter (EKF) for the Permanent Magnet Synchronous Motor (PMSM) sensorless control using an ARM Cortex-M3 microcontroller. A various optimization levels based on arithmetic calculation reduction was implemented in ARM Cortex-M3 microcontroller. The execution time of EKF estimator was reduced from 260.4 μs to 37.7 μs without loss of accuracy. To further reduce EKF execution time, the separation of a Kalman gain and covariance matrices calculation from prediction and measurement state update, a novel method was proposed, and the performance of it an EKF estimator with separation of a Kalman gain and covariance matrices calculation from prediction and measurement state update was analyzed. Simulation and experiments results validate that the proposed technique could provide the same accuracy with less computation time. A tendency of minimum Kalman gain and covariance matrices calculation frequency from rotor ele... [more]