Carrier Operations Research Articles

Optimal operation of multi-energy carriers considering energy hubs in unbalanced distribution networks under uncertainty

This article presents a two-stage stochastic programming model to address the dispatching scheduling problem in an energy hub, considering an unbalanced active low-voltage (LV) network. A three-phase version of the second-order cone relaxation of DistFlow AC optimal power flow (AC-OPF) is employed to incorporate unbalanced network constraints, while the objective minimizes the Local Energy Community (LEC) operational cost. The model results have been validated using OpenDSS, encompassing energy losses, voltage levels, and active/reactive power. Likewise, a comparative analysis between the three-phase model and the traditional single-phase model, using a modified version of the IEEE European LV Test Feeder as a case study, reveals interesting differences, such that the single-phase model underestimates voltage limits during photovoltaic (PV) system operation and overestimates energy purchased from the main grid, compared with the three-phase model. Similarly, the comparison results reveal that discrepancies between the single and three-phase models intensify as the power injected from PV systems rises. This notably impacts the total energy purchased from the grid, battery operation, and the satisfaction of thermal consumption through electricity. Finally, while the three-phase model offers valuable insights into security levels for voltage and grid energy purchase, its longer computational time makes it more suitable for strategic use rather than daily operational frameworks.

The changes in the approach to the realization of "Green Deal" goals of Polish large and medium-sized road carriers as a result of the COVID-19 pandemic

The purpose of the article is to show changes in the operation of Polish large and medium-sized road carriers in the context of the EU's pro-environmental requirements contained in the Green Deal in the post-pandemic period. The decline in the number of transport orders resulting from the general slowdown in the economy during the COVID-19 pandemic undoubtedly had an impact on the turnover of road carriers and, consequently, on funding for investment projects, including environmentally friendly investments. Verifying the magnitude and direction of such changes seems a much-needed aspect of the research in the context of the Green Deal's unchanging high demands. The research that was conducted shows the impact of the pandemic on the investment decisions and activities of transport companies and the reality of post-pandemic transport. The practical application of the research results is very useful, primarily as guidance for road carriers in the context of Green Deal.

Evaluating the Impact of Airport Design and Operations on the Efficiency of Part 139 Certificated Airports in the South and Southeast United States

Several studies in the past have explored the relationship between various airport related variables and operations (Javanmard et al., 2024; Khireldin & Law, Li & Trani, 2017; Mott et al., 2016). This study delves into the impacts of airport design, runway characteristics, services, classifications, and comprehensive data sets on the operational volume of Part 139 certificated airports in the United States. Employing a hierarchical multivariate regression model, the research addresses the influence of various airport-related factors on operational volumes. Initial findings indicated significant associations between several key variables such as and operational volume, with runway length and the scale of air carrier and general aviation operations being particularly influential. The research also critically evaluated and refined the selection of variables based on statistical significance and multicollinearity, leading to a focused analysis on the most impactful factors. Despite initial assumptions that all proposed variables would be significant, the study refined these inputs to better align with observed data, enhancing the model's predictive accuracy and reliability. This paper provides valuable insights into airport operational dynamics, supporting future policy decisions and strategic planning in airport management.

EN Methods for managing the energy efficiency of a reliquefaction plant operating on the reverse brighton cycle of a LNG tanker

LNG is transported over long sea and ocean distances only by tankers, called LNG carriers, in large on-board tanks at a temperature of -163ºC. Although these tanks are well insulated, some of the LNG evaporates under the external factors influence, and boil-off-gas gas (BOG) is formed. The main method of dealing with BOG is the reliquefaction of LNG. Many LNG carriers use technology based on the reverse Brighton cycle (RBC) for reliquefaction. The study has been carried out by thermodynamic analysis methods of the actual parameters and characteristics of the BOG reliquefaction plant based on the data obtained during the operation of the LNG carrier “UMM AL AMAD”. Energy and entropy-statistical methods of thermodynamic analysis have been used in the research. The reliquefaction plant operation has been evaluated based on the specific compression work consumption and the value of the effectiveness of a thermodynamic cycle. The analysis of the results showed that the investigated system operating according to the Brighton cycle has low energy efficiency values. The most energy-intensive loop is the nitrogen loop. It accounts for over 90% of the work overspending in the reliquefaction plant. The expander work partially compensates for the overexpenditure of compressor work. Irreversibility in the expander is 7.7%, and the N2 compressor is approximately 48.7% of the total irreversibility of the liquefaction process. In the BOG/LNG loop, the main contribution to the processes’ irreversibility is made by the BOG compressor (~3.7%) and the precooler (~1.55%) of the total irreversibility of the liquefaction process. The cryogenic heat exchanger is a component of both loops and its negative impact is estimated at 36.4% of the total irreversibility of the liquefaction process. The application of reliquefaction plants operating on the Brighton cycle is currently inefficient due to low energy efficiency and huge losses in the nitrogen loop, which does not meet IMO requirements for gas carriers

Optimal resource allocation and operation for smart energy hubs considering hydrogen storage systems and electric vehicles

Energy hubs (EHs) have substantially paved the way for the coordinated operation of various energy carriers, converters, and storage. However, the establishment of optimal planning and operation of the EH include several challenges, e.g., the stochastic nature of non-dispatchable generation assets, obtaining a satisfactory performance from the storage assets with reasonable energy and power density costs, and long-term load growth. Accordingly, this paper proposes a two-stage stochastic optimal resource allocation and operation approach for multiple smart energy hubs-based microgrids. The first stage optimizes the location of each EH and different assets' capacities. On the other hand, the second stage optimizes the charging/discharging rates of each asset and parking lot power. These microgrids combine renewable energy sources. Moreover, for research gap and unlike existing research, the cooperative operation of hybrid storage systems (i.e., solar-powered compressed air energy storage, hydrogen storage systems, battery energy storage systems, thermal energy storage systems) along with plug-in electric vehicles (PEV) has been investigated. Furthermore, annual load growth and price-based demand response (PBDR) are employed in this study. The simulation results demonstrate that the controlled charging/discharging of the PEVs reduces the total annualized cost by 5.49%, while the operation and emission costs are reduced by 21.3% and 19.86%, respectively. Furthermore, employing PBDR has led to a reduction of 10.1% in capital and operational costs.

Culture and human factors in aviation security

Culture and human factors in aviation environment are not new concepts. They have been primary components of the aviation safety system and have become fundamental to the operations of air carriers. Their significance in ensuring safe aviation practices is widely recognised and accepted today. These concepts have been seamlessly integrated into the organisational DNA of aviation safety, shaping core principles and practices. In contrast, aviation security has historically lagged behind, often seen merely as a component of the broader safety framework. Over the years, safety and security have evolved separately, reflecting their distinct natures. While aviation safety has reached a high level of maturity, aviation security is now in a position where it must catch up. Current aviation security staff recruitment and retention challenges need to be addressed by creating better strategy for future recruitment, professionalisation of security workforce and improved airport environment. Embedding strong and effective security culture, consideration of human factors and their impact on staff performance and development of mission valence can positively affect airport working environment, leading to better staff retention and positive perception of aviation security roles.

Construction of flight planning and loading courses under the new generation transportation system

Facing the development of the new generation of air transportation, the Civil Aviation Administration of China has successively promulgated the CCAR-121-R5-R7 version of the "Certification Rules for the Operation of Large Aircraft Public Air Transport Carriers". With the introduction of the latest national regulations, existing teaching materials and teaching content are no longer suitable for student training needs. Through the construction of industry-university collaborative education projects, analyze the connotation and extension of flight planning and loading courses, compile new teaching materials for flight planning and loading courses, establish a good teaching team for flight planning and loading courses, and form flight planning and loading courses. The course's on-campus teachers and industry experts have jointly created an online and offline teaching model, and established an assessment system that combines standard answer exams and non-standard answer exams for flight planning and loading.

Design Improvement Using Topology Optimization for the Structural Frame Design of a 40 Ft LNG ISO Container Tank

LNG ISO tank containers are a solution for bulk liquefied natural gas (LNG) delivery to the outer islands of Indonesia that are not connected to the gas pipeline network. The design of an ISO tank frame must consider two critical parameters, strength/rigidity and weight saving, which affect the operational performance of the distribution process. The current investigation aims to numerically optimize the design of the structural frame of a 40 ft LNG ISO tank for a mini LNG carrier operation using a topology optimization framework. Two design solutions are used in the topology optimization framework: reducing the strain energy and mass retained. Mass retained was selected as the objective function to be minimized, which was assumed to be 60–80%. The proposed frame design is tested using three operational loading scenarios, including racking, lifting, and stacking tests based on the ISO 1496 standard. The convergence mesh tests were initially evaluated to obtain the appropriate mesh density in the finite element analysis (FEA). The simulation findings show that the topology optimization method of the frame design resulted in an improved design, with an increase in the strength-to-weight saving ratio. A promising result from the optimization scenario demonstrates weight savings of about 18.4–37.3%, with experienced stress below the limit criteria. It is found that decreasing mass retained causes a significant stress increase in the structural frame and ISO corner castings, especially in the stacking load. The critical recommendation in the frame design of the LNG ISO tank can be improved by eliminating the saddle support and bottom frame and increasing the thickness of the vertical frame.

Design Considerations in Electric Multi-Tool Carrier for Protected Cultivation

The design considerations of a prototype electric multi-tool carrier rely heavily on the selection of a prime mover, where the Brushless DC (BLDC) motor emerges as the optimal choice. The BLDC motor's compact size, reduced weight, and high torque output make it well-suited for the intended agricultural operations. The transition from the prime mover to the power transmission system involves determining the ground wheel diameter and achieving a target speed of 10 km/h. The calculated speed ratio of the BLDC prime mover to the power transmission system (25:1) ensures efficient and synchronized multi-tool carrier operation. During testing, the BLDC prime mover exceeded expectations, producing a torque of 90.24 Nm, surpassing the specified requirement of 67.53 Nm. This robust performance highlights the prime mover capability to meet and exceed operational demands across varying speeds. The meticulous consideration of torque requirements in the design phase validates the BLDC motor's efficiency for the proposed electric multi-tool carrier, emphasizing its suitability for the envisioned application.

Structural assessment of 40 ft mini LNG ISO tank: Effect of structural frame design on the strength performance

Abstract Due to the escalating demand for liquefied natural gas (LNG) as a low-emission and environmentally friendly energy source, ISO tank containers have emerged as an innovative solution to facilitate efficient and cost-effective mass transportation. The 40 ft ISO tank container, which encompasses a pressure vessel structure, is a versatile intermodal unit that seamlessly integrates into sea and land transportation networks. The main objective of this study is to present a comprehensive analysis for assessing the various frame design scenarios of the 40 ft ISO tank container for mini LNG carrier operation. The assessment is conducted under the provisions outlined in ASME Section VIII Division I code, which governs the design standards for boilers and pressure vessels. The finite-element analysis (FEA) scrutinizes three different structural design alternatives: frame thickness, the addition of support plates, and the addition of saddle supports, which are subjected to various loading conditions: stacking, lifting, and racking load tests. The analysis offers a comparative assessment of the safety level provided by the ASME design guidance in contrast to the FEA judgments based on ISO standards. It can be found that stacking and longitudinal load tests are more critical operational load scenarios. Increasing the frame thickness of the LNG ISO tank is more practical in increasing structural weight savings than adding more saddle supports and support plates.

Analysis of the front carrier stability considering real-time offset of the spreader

Frontal carrier is often used to stack and transfer containers at freight terminals or inland transfer stations, and the requirement of its security is increasing. Since the lifting point is located in front of the vehicle body, it is also necessary to move the spreader left or right in real time to adjust the position of the lifting point during the lifting process. While the boom extends forward and the lifting load is large, the front carrier will be in a state of unbalanced stress, which increases the hidden danger of the front carrier overturning forward. This paper analyzes the influence of spreader offset on the change of overturning line of the frontal carrier while the frontal carrier is lifting a large load, establishes the coefficient to measure the anti-overturning stability of the frontal carrier, calculates the real-time lifting point position of the frontal carrier, and analyzes the spatial force system of the frontal carrier. By comparing the influence of spreader offset on the anti-overturning stability coefficient of the frontal carrier under different typical lifting conditions, this paper analyzes the change of anti-overturning stability coefficient, and gives the stability area diagram under given load, which provides a certain judgment basis for the safe operation of the frontal carrier.

Learnings from the simulation of use cases in city logistics in the HARMONY project

City logistics simulation can help to provide empirical proof of potential benefits of new solutions in city logistics but decision support tools for such analyses are scarce because of a lack of empirical data and resources. The Tactical Freight Simulator (TFS) is a multi-agent simulator that represents the decision-making of freight agents and individual freight shipments. In this study it is applied to four distinct use cases in city logistics: micro hubs, introduction of zero-emission zones, crowd-shipping and the land use planning of logistic facilities.The simulations show impacts of each development and provide learnings: the type of open or single carrier operation of micro hubs have big local impacts. The impact of freight traffic avoiding zero emission zones can have substantial local impacts. Depending on the configuration of the service, crowd-shipping can lead to more vehicle kilometres. A common finding is the impact of the chosen scenario parameters on the outputs: regulation is important to shape city logistics operations. This also illustrates that, although the technology seems to be ready for innovative solutions, the logistical organisation or business models and policies are not yet well developed.

Full-Service Carrier (FSC) vs Low-Cost Carrier (LCC): Purchasing Decision-Making Process of Passengers

The demand for the aviation industry has grown as a result of the shift in people's travel preferences brought on by rising wealth and expanding trade in the world and in our nation. Air travel is now preferred due to state assistance, new airports, superior aircraft, and the relative drop in expenses. This study's main focus is on the consumer purchase patterns of two airline companies that operate in the very competitive aviation sector. Depending on whether the airline is a full-service carrier or a low-cost carrier, these variables change. The "Factors Affecting Airline Preferences Scale" was created and distributed to passengers of two airline organizations at Istanbul Sabiha Gökçen Airport (a full-service carrier (FSC) and a low-cost carrier (LCC) operating in Turkey) to assess the extent to which variables like airline reputation, advertising, frequent flyer programs, price, service quality, and digital marketing tools like websites, e-mails, Facebook, Twitter, Instagram, YouTube, and mobile applications have an impact on the process of ticket purchasing decision of passengers. It was shown that the passengers' purchasing decisions were influenced by reputation, service quality, frequent flyer programs, price, digital marketing initiatives, and advertisement. It was shown that depending on whether the airline is a full-service carrier or a low-cost carrier, the impact of these elements differs.

A Modified Weighted Connectivity Ratio for Measuring a Low-cost Carrier's Connectivity at its Major Airports

This study aims to analyze how good and efficient the low-cost carriers' connectivity is at their major airports by studying one of the largest low-cost carriers in the world, AirAsia Group. Weighted Connectivity Ratio is used in the calculation, applied with slight modifications to suit the operations of low-cost carriers at their airports. The results reveal that some airlines have very good connectivity, even when it is compared to the connectivity of several big full-service carriers in Europe. This research brings a novelty in the form of an analysis of connectivity of low-cost carriers, considering that most of the previous research only focused on the connectivity of full-service carriers that implement a hub-and-spoke strategy. This is important because low-cost carriers are currently present with a very rapid growth as an alternative flight option that is more affordable for passengers in addition to full-service carriers that have previously dominated the aviation market.

Investigating the Operation of an LNG Carrier as a Floating Power Generating Plant (FPGP)

The paper provides a novel alternative solution for the old generation turbine LNG carriers (LNG/Cs) in order to extend their life cycle, thus avoiding their demolition. Nowadays, the use of liquefied natural gas (LNG) as fuel for the production of electricity is predominant against other fossil fuels. LNG has been widely recognized as the most promising alternative fuel, combining both high efficiency and environmental friendliness. The old generation of steam turbine LNG/Cs with the distinct disadvantage of a low thermal efficiency ratio, leading to higher fuel costs, are coming to a crossroad, which is either to keep the vessel on duty until the end of their life cycle, earning low fares as those are not preferred from the charterers, or to change the use of the vessel, converting them either to a FSRU (floating storage regasification unit) or to a FPGP (floating power generating plant). In this paper, the last alternative is proposed via a holistic examination of the techno-economical (the CBA performed calculates all related metrics) but also in terms of the electric energy market by utilizing power purchase agreements (PPAs) and the contracts for difference (CfDs). This conversion into an FPGO is a novel approach providing a ‘win–win’ solution scheme, on the one hand, to areas with the non-economical bunkering chain of LNG along with non-expensive electricity production, while on the other hand, it provides an extension of the profitable life cycle of the LNG/Cs under study, which would otherwise have been considered of obsolete technology. The proposition is supported by figurative numerical case studies that help extract tangible conclusions regarding the degree of the investment viability.

Solar-driven biomass steam gasification by new concept of solar particles heat carrier with CPFD simulation

Solar-driven biomass gasification is a promising solar thermochemical technology to produce green H2-enriched syngas, and contribute to solar energy upgrade and efficient conversion. Whereas, the continuous and stable operation of solar-driven biomass gasification is challenging due to the non-uniform concentration of solar flux and its fluctuating nature. In this regard, a novel concept of solar-driven gasification is proposed, using solar-heated particles as the heat carrier, and biomass steam gasification in a fluidized bed reactor is numerically investigated based on the computational particle fluid dynamics (CPFD) model. The complex distributions of gas and particle phases, as well as the effects of operation parameters on syngas species are comprehensively analyzed. Results indicate that the biomass material and solar-heated particles can be well-mixed through continuous feeding, and the internal heat transfer and gasification kinetics are enhanced. The mole fraction of H2 and CO in the produced syngas reach to 50.86% and 18.97% under the benchmark operating condition. By using the high-temperature quartz sand as the solar particles heat carrier, the long-term and continuous operation of the endothermic gasification process can be achieved. The newly developed solar-driven biomass gasification method provides a promising approach to mitigate the impact of the fluctuating solar irradiation and enhance the operational flexibility of gasification process.

On urban co-modality: Non-cooperative and cooperative games among freight forwarder, carrier and transit operator

This paper models a public transit system that can serve both passengers and urban freight, i.e., urban co-modality, and investigates the system-wide impacts of co-modality on existing urban freight forwarding service, freight carrier and urban transit services. In the co-modal system, we model one transit operator that serves passengers and provides co-modal services, one freight forwarder (an intermediary) that serves freight customers and uses freight transportation services provided by a freight carrier or the transit operator, and one freight carrier that provides services to the freight forwarder. We derive the analytical conditions under which co-modal operations can improve the profits of the freight forwarder, carrier and transit operator, and the consumer surpluses of freight customers and passengers compared with the status quo without co-modality. We also analytically and numerically compare the optimal operation decisions, the three operators’ profits, and the users’ welfare under different games among the operators (non-cooperative and cooperative games). Our results show that when the three operators are in a non-cooperative relationship, the freight carrier might have a profit loss due to the decreased freight units allocated to the direct road channel; whereas, both the freight forwarder and the transit operator would have profit gains from the co-modality. The numerical studies further reveal that to ensure a Pareto-improving co-modal system, the operators have to reduce the freight/transit service fare and co-modal transportation price.

A Power Quality Assessment of Electric Submersible Pumps Fed by Variable Frequency Drives under Normal and Failure Modes

This paper proposed a simplified modeling approach for a power quality (PQ) assessment of Electric Submersible Pumps (ESP) systems supplied by the two-level, the neutral-point-clamped three-level, and the cascaded H-bridge (CHB) multilevel inverter VFD topologies. The VFD switching function models and their analytical expressions are proposed to understand how they can create high-frequency components that might excite the resonance mode in a transmission cable or a rotating shaft system. Voltage, current, and motor airgap torque harmonics induced by each VFD topology in a balanced operation mode are derived and correlated to the PWM carrier and motor operating frequencies. The motor airgap harmonics are calculated based on Concordia’s transformation of voltages and currents in αβ-plan. These harmonic components are represented in the form of Campbell diagrams. An analysis of harmonics under unbalanced conditions was also conducted in a CHB VFD topology-powered ESP system with failed and bypassed cells. The investigated modulation technique is a neutral-shift PWM method that enables the system to operate balanced line-line voltages even if the line-neutral voltages are unbalanced. The effects of modifying the electrical spectrum using the neutral-shift PWM method on electrical and mechanical spectra are analyzed. The results of the Matlab/Simulink-based simulation show that the proposed full ESP system model is highly accurate in both normal and failure modes. The results are consistent with theoretical predictions and are graphically shown in the time and frequency domains for easy analysis. Hybrid experimental–numerical results on a reduced-scale laboratory setup are also discussed to confirm the correctness of the suggested developments.

Assessment of key risk factors in the cold chain logistics operations of container carriers using best worst method

Given that reefer containers are highly dependent on their temperature control function, container carriers must pay particular attention to the risks occurring during cold chain logistics. Assessment of cold chain safety risks can therefore reduce chance of accidents and concern for product damage. The goal of this study was to use the best worst method (BWM) to assess key risk factors in container carriers' cold chain logistics operations. After gathering relevant information from the literature and conducting expert interviews, this study preliminarily determined risk factors affecting container carriers' cold chain logistics operations, and obtained 15 risk factors in 3 risk assessment aspects. A BWM model was then developed and tested using empirical data from a questionnaire survey of experts. The results indicated that (1) the “shipper risk” aspect is the most important risk link for container carriers' cold chain logistics; (2) the 6 key risk factors with the greatest effect on container carriers' cold chain logistics are “excessively long container loading time,” “insufficient pre-cooling of goods,” “poor or improper product packaging,” “dockside or shipboard power supply system malfunction,” “improper cargo stacking,” and “human error affecting temperature settings.” As a reference for container carriers engaging in cold chain logistics, this study also suggests risk management strategies intended to enhance cold chain safety and performance.

Перспективы транспортировки грузов в границах стран пространства 1520

Purpose: To assess the importance of multimodal cargo transportation for the economy of 1520 area countries. This study confirms the need to expand the capabilities of railway infrastructure despite the consequences of sanctions restrictions, international political situation uncertainty and trans-Eurasian container transportation imbalance with the purpose to achieve economic growth of the national economies of 1520 area countries. Methods: There were used analytics and diagnostics methods for the data (observation, analysis, synthesis) of regulatory and legal provisions governing relations within the framework of freight transportation by railway network as well as reports of leading railway companies of 1520 area countries - JSC "Russian Railways", JSC "NC "Kazakhstan Temir Zholy", Belarussian Railways and others, Russian and foreign forwarding companies, carrier operators, data from Russian Federation Federal Customs Service and foreign customs authorities, statistical and analytical informational databases. Results: The characteristics for main railway systems of 1520 area leading countries are given with specification of the number of international and domestic container and container-piggyback routes. The factors influencing the development of freight transportations on Russia territory along 1520 track have been identified, the prospects for cargo transportation have been assessed in view of Russia transport and logistics market current state. Practical significance: The obtained results have applied character since they offer and justify measure series to ensure effective development of multimodal transportations given existing infrastructure limitations.