Direct Operating Costs Research Articles

Multidisciplinary optimization methodology for truss-braced wing aircraft using high-fidelity structure sizing

In this research, a method is developed to optimize the truss-braced wing aircraft configuration in a multidisciplinary design framework. Physics-based high-fidelity methods, that can capture the nature of the configuration changes, are employed for the disciplines where the existing classical methods are not reliable. High-fidelity geometry modeling, structure loading, structure optimization, and aeroelastic sizing methods are integrated into the aircraft multidisciplinary design and optimization. The developed algorithm is applied for the multi-objective optimization of a regional jet aircraft to minimize the cost and weight. The results demonstrate that the cost-optimum solution converges to a higher aspect ratio wing equipped with a higher bypass ratio engine, and a 7.94% reduction in the direct operating cost can be achieved. On the other hand, the weight-optimum wing planform tends to a slightly lower aspect ratio wing with a lower bypass ratio engine, while a 6.18% reduction in take-off weight is achieved. In addition to that, the findings of this study highlight the considerable effect that the engine technology has on the optimum layout, which suggests that the engine technology and its performance should also be a part of the design optimization process. The developed modular framework offers further optimization potential for the truss-braced wing aircraft, as more detailed models can be integrated.

Hospital charges for laparoscopic sleeve gastrectomy compared to robotic sleeve gastrectomy: a multicenter study.

Sleeve gastrectomy has become a gold standard in addressing medically refractory obesity. Robotic platforms are becoming more utilized, however, data on its cost-effectiveness compared to laparoscopy remain controversial (1-3). At NYU Langone Health, many of the bariatric surgeons adopted robotic surgery as part of their practices starting in 2021. We present a retrospective cost analysis of laparoscopic sleeve gastrectomy (LSG) vs. robotic sleeve gastrectomy (RSG) at New York University (NYU) Langone Health campuses. All adult patients ages 18-65 who underwent LSG or RSG from 202 to 2023 at NYU Langone Health campuses (Manhattan, Long Island, and Brooklyn) were evaluated via electronic medical records and MBSAQIP 30-day follow-up data. Patients with prior bariatric surgery were excluded. Complication-related ICD-10/CPT codes are collected and readmission costs will be estimated from ICD codes using the lower limit of CMS transparent NYU standard charges (3). Direct charge data for surgery and length of stay cost data were also obtained. Statistical T-test and chi-squared analysis were used to compare groups. Direct operating cost data at NYU Health Campuses demonstrated RSG was associated with 4% higher total charges, due to higher OR charges, robotic-specific supplies, and more post-op ED visits. RSG was associated with higher overall hospital charges compared to LSG, though there are multiple contributing factors. More research is needed to identify cost saving measures. This study is retrospective in nature, and does not include indirect costs nor reimbursement. Direct operating costs, per contractual agreement with suppliers, are only given as percentages. Data are limited to 30-day follow-up.

Investigation of Hybrid Laminar Flow Control Capabilities from the Flight Envelope Perspective

The present work conducts a multifidelity aerodynamic design of a medium-range commercial aircraft wing featuring hybrid laminar flow control (HLFC) technology. The design was performed to investigate the capabilities of the HLFC, considering the entire design flight envelope, low-speed performance requirements, and various potential mission scenarios. A combination of medium-fidelity aerodynamic design tools for laminar flow control using MSES-COCO-LILO, CFD RANS for high-lift cases, the quasi-three-dimensional for database generations, and SUAVE for mission analysis were used to design and assess aircraft’s performance with the HLFC wing. Studies of the design objective demonstrated a conflict between friction and compressibility drag that strongly affects the design objective function and the wing performance at various off-design conditions. A strong dependence of HLFC on flight conditions was observed to indicate technology performance limitations and a tradeoff between airplane emissions, range, and costs. Finally, a comparison of medium- and low-fidelity performance results showed deviations in the design fuel burn of 4%, a minimum possible harmonic range difference of 3%, and direct operating costs of 2%. The outcome suggests the need for better compressibility and parasite drag models for early design stages to accurately model the HLFC technology without introducing complicated methods at the first sizing steps.

Modelling the impact of introducing first-generation narrowbody hydrogen aircraft on the passenger air transportation network in Europe

The global aviation industry faces a pronounced challenge to mitigate its contribution to anthropogenic climate change, which is caused by burning fossil fuels. One potential pathway is the transition towards using green hydrogen as zero-carbon fuel. Next to technological, infrastructural, and economical challenges, this would introduce a wide range of operational and infrastructural changes to a system centred around safety and reliability. This study employs a holistic approach and examines these changes from a flight network perspective, focusing on passenger transport in Europe. It utilizes network modelling and linear optimization techniques to determine network changes imposed by the introduction of first-generation narrowbody hydrogen aircraft. The findings are threefold: First, the study shows that the air transportation network can be adequately re-created using demand and direct operating cost optimization only, without considering revenue and airline-specific factors. Second, the introduction of hydrogen aircraft will have substantial impact on network structure, incl. flight frequency, capacity, and stopover routes, depending on seat capacity and range of the hydrogen aircraft design. Lastly, it also shows that airports that have a favourable green hydrogen supply will benefit from the introduction of hydrogen aviation.

Efficient recycling of sewage water in a polyester integrated industry: A case study

The water reuse system in a petrochemical and polyester integrated industry in Zhejiang, designed to handle industrial circular sewage, had a capacity of 1600 m3/h. The system employed a process comprising a high-efficiency sedimentation tank, V-shaped filter, aerated biological filter, ultrafiltration, and reverse osmosis. The high-efficiency sedimentation tank's mud water drainage, along with pretreatment through the biological aerated filter (BAF), V-shaped filter, and ultrafiltration system, resulted in an overall system recovery rate of 70 %. Actual operational results indicated removal rates exceeding 70 % for chemical oxygen demand (COD) and 94 % for chloride ions. The effluent water had a COD of ≤ 20 mg/L, chloride ion concentration of ≤ 50 mg/L, and conductivity of ≤ 20 μS/cm. Given the high recovery rate and the use of domestically produced ultrafiltration membranes, the direct operational cost of the system amounted to a mere 6.28 yuan/m3. This led to a reduction of approximately 9.67 million tons of wastewater discharged annually, fulfilling the objective of recycling industrial sewage for reuse.

Integrated Hybrid Engine Cycle Design and Power Management Optimization

Abstract A novel integrated gas turbine cycle design and power management optimization methodology for parallel hybrid electric propulsion architectures is presented in this paper. The gas turbine multipoint cycle design method is extended to turboprop and turbofan architectures, and several trade studies are performed initially at the cycle level. It is shown that the maximum degree of electrification is limited by the surge margin levels of the booster in the turbofan configuration. An aircraft mission-level assessment is then performed using the integrated optimization method initially for an A320 Neo style aircraft case. The results indicate that the optimal cycle redesigned hybrid electric propulsion system (HEPS) favors takeoff and climb power on-takes while optimal retrofit HEPS favor cruise power on-takes. It is shown that for current battery energy density (250 Wh/Kg), there is no fuel burn benefit. Furthermore, even for optimistic energy density values (750 Wh/kg) the maximum fuel burn benefit for a 500 nm mission is 5.5% and 4% for redesigned and retrofit HEPS, respectively. The power management strategies for HEPS configurations also differ based on gas turbine technology with improvement in gas turbine technology showing greater scope for electrification. The method is then extended to ATR 72 style aircraft case, showing greater fuel burn benefits across the flight mission envelope. The power management strategies also change depending on the objective function, and optimum strategies are reported for direct operating cost or fuel burn. The retrofit case studies show a benefit in direct operating cost compared to redesigned case studies for ATR 72. Finally, a novel multimission approach is shown to highlight the overall fuel burn and direct operating cost benefit across the aircraft mission cluster.

The pathway to net-zero emission in aviation – How much can we rely on sustainable aviation fuel?

The aviation industry is under constant pressure to reduce its environmental footprint and eventually achieve net-zero carbon emissions by 2050. In order to accomplish this ambitious but necessary goal, a variety of measures have been employed over the last two decades, among which the application of sustainable aviation fuels (SAFs) plays a prominent role. Policymakers aim at substituting 80-90% of aviation fuel by SAF in 2050, thus reducing global aviation CO2 emissions by 62%. In theory, these fuels can already be integrated in up to 50% of the fuel capacity of current aircraft as “drop-in” fuels. However, due to numerous operational and regulatory barriers surrounding the exploitation of SAF, it is still not clear how, in combination with traditional jet fuel, it will affect the cost aspect of airline operations. Considering the traffic projection provided by EUROCONTROL according to which the traffic will undoubtedly increase in the next decade, the aim of the paper is to provide a preliminary assessment of the financial impact of SAF on an airline's total fuel cost. For this purpose, the analysis is based on a single carrier that follows a hybrid business model and mainly focuses its operation on intra-European routes. Creating different scenarios for SAF's future costs as well as the share of SAF in total fuel required, this paper provides some realistic results that may serve as a solid foundation for the airline to better understand the implications of SAF on its financial aspects, keeping in mind that fuel costs still constitute a large portion in an airline's direct operating costs. The proposed methodology may be applied to any carrier with an interest in SAF.

ВПЛИВ СПОСОБІВ СІВБИ НА ЕФЕКТИВНІСТЬ ВИРОЩУВАННЯ СОНЯШНИКА В УМОВАХ ЗАХОДУ УКРАЇНИ

The purpose of research: to determine the influence of different methods of sowing on the formation of seed yield and the efficiency of sunflower cultivation in the soil and climatic conditions of Western Ukraine. Methods. Field research was conducted in the soil and climatic conditions of Western Ukraine. The experimental field was characterized by sod deep clayey sandy soils. Two methods of sunflower sowing were studied: traditional with a row spacing of 70 cm using a «Gaspardo Renata R MTR 8» precision seeding vacuum planter and narrow-row sowing with a row spacing of 12.5 cm – the «Gaspardo Corona 600» seeding complex. During the research, the structural elements of sunflower seed productivity and the efficiency of two methods of sowing were estimated. Results: According to the research results it was established that in the variant with traditional sowing the average number of seeds in the basket was greater. The same trend was also observed concerning basket size, seed weight, and productivity of one plant, which made it possible to form a sunflower seed yield of 1.67 t/ha, which is 0.14 t/ha (by 9.1%) more than in the plot with narrow-row sowing. Direct operational use of technical means for performing technological operations of soil preparation, fertilizer application, and seed sowing in traditional sowing amounts to UAH 2,541/ha and is higher by UAH 667/ha compared to costs in the narrow-row variant. However, due to the higher yield in the version of traditional sowing, a higher income from the sale of seed was obtained by 1890 hryvnias/ha. Therefore, the effectiveness of the applied technical and technological solutions on the plot with traditional sowing amounted to 1223 hryvnias/ha. Conclusions. The «Gaspardo Corona 600» sowing complex can perform narrow-row sowing of sunflower seeds with the specified sowing rate in the conditions of Western Ukraine. Although a slightly lower yield was obtained in the variant with narrow-row sowing, direct operating costs for pre-sowing soil cultivation and sowing are lower than for technical and technological solutions for implementing traditional wide-row sowing. The results of using the «Gaspardo Corona 600» sowing complex for sunflower sowing can be useful for farmers when deciding to buy a row drill and save the financial resources of farms. Keywords: sunflower, methods of sowing seeds, row seeder, sowing complex, productivity, efficiency.

ЗАСТОСУВАННЯ ОПЕРАТИВНОГО МЕТОДУ ВИЗНАЧЕННЯ ТИПАЖУ ТА КІЛЬКІСНОГО СКЛАДУ МАШИН ДЛЯ ЗАГОТІВЛІ ДЕРЕВИНИ В УМОВАХ ДП «ЛІСИ УКРАЇНИ»

The purpose of research: to determine the influence of different methods of sowing on the formation of seed yield and the efficiency of sunflower cultivation in the soil and climatic conditions of Western Ukraine. Methods. Field research was conducted in the soil and climatic conditions of Western Ukraine. The experimental field was characterized by sod deep clayey sandy soils. Two methods of sunflower sowing were studied: traditional with a row spacing of 70 cm using a «Gaspardo Renata R MTR 8» precision seeding vacuum planter and narrow-row sowing with a row spacing of 12.5 cm – the «Gaspardo Corona 600» seeding complex. During the research, the structural elements of sunflower seed productivity and the efficiency of two methods of sowing were estimated. Results: According to the research results it was established that in the variant with traditional sowing the average number of seeds in the basket was greater. The same trend was also observed concerning basket size, seed weight, and productivity of one plant, which made it possible to form a sunflower seed yield of 1.67 t/ha, which is 0.14 t/ha (by 9.1%) more than in the plot with narrow-row sowing. Direct operational use of technical means for performing technological operations of soil preparation, fertilizer application, and seed sowing in traditional sowing amounts to UAH 2,541/ha and is higher by UAH 667/ha compared to costs in the narrow-row variant. However, due to the higher yield in the version of traditional sowing, a higher income from the sale of seed was obtained by 1890 hryvnias/ha. Therefore, the effectiveness of the applied technical and technological solutions on the plot with traditional sowing amounted to 1223 hryvnias/ha. Conclusions. The «Gaspardo Corona 600» sowing complex can perform narrow-row sowing of sunflower seeds with the specified sowing rate in the conditions of Western Ukraine. Although a slightly lower yield was obtained in the variant with narrow-row sowing, direct operating costs for pre-sowing soil cultivation and sowing are lower than for technical and technological solutions for implementing traditional wide-row sowing. The results of using the «Gaspardo Corona 600» sowing complex for sunflower sowing can be useful for farmers when deciding to buy a row drill and save the financial resources of farms. Keywords: sunflower, methods of sowing seeds, row seeder, sowing complex, productivity, efficiency.

Fan Stage Design and Performance Optimization for Low Specific Thrust Turbofans

In modern turbofan engines, the bypass section of the fan stage alone provides the majority of the total thrust required in cruise, and the size of the fan has a considerable effect on the overall engine weight and nacelle drag. Thrust requirements in different parts of the flight envelope must also be satisfied together with sufficient margins towards stalling. An accurate description of the interdependencies between the relevant performance and design attributes of the fan stage alone—such as efficiency, surge margin, fan-face Mach number, stage loading, flow coefficient, and aspect ratio—are therefore necessary to estimate system-level objectives such as mission fuel burn and the direct operating cost with enough confidence during the conceptual design phase. The contribution of this study is to apply a parametric optimization approach to the conceptual design of fan stages for low specific thrust turbofans based on the streamline curvature method. Trade-offs between fan stage attributes for Pareto-optimal solutions are modeled by training Kriging surrogate models on the results from the parametric optimization. A case study is provided in the end to demonstrate the potential implications of including a higher level of fan-stage parameter interdependency in an engine systems model. Results implied that being able to predict the rotor solidity required to maintain a given average blade loading—in addition to stage efficiency—is of significant importance when it comes to evaluating the trade-off between engine weight and thrust-specific fuel consumption.

Multi-control commercial aircraft trajectory optimization in a vertical plane with state-inequality constraints via singular control theory

We present a computational framework based on singular control theory to optimize commercial aircraft flights in a vertical plane. The optimization problem involves the lift coefficient (a regular control), and throttle setting (a singular control). However, given a small aerodynamic path angle typically associated with commercial aircraft flights and the significant time-scale separation in flight dynamics, it is customary to treat the aerodynamic path angle as a singular control and replace the lift coefficient as a function of states. This results in a model that is singular on both controls. This research sheds light on several key challenges that have either been unexplored, such as the possibility of switches in both controls even during a specified flight phase, or underexplored, such as state-inequality constraints and wind shear, in relation to the pure singular model. Adhering to the Pontryagin’s maximum principle, we develop a switching-point algorithm to solve the pure singular model for the direct operative cost. Extensive analysis is conducted to understand the impact of various relaxed parameters. The simulation results obtained from the pure singular model are validated through first and second order optimality conditions. Finally, we compare the solutions obtained from the pure singular model with those of the original model, ultimately concluding that the pure singular model yields exceptionally accurate results. In conclusion, the paper highlights the computational time and accuracy advantages of the proposed optimization framework. Furthermore, it underscores the noteworthy observation that the sensitivity of the associated Hamiltonian system with respect to aircraft mass is marginal.

A Study on Quantities Driving Maintenance, Repair, and Overhaul for Hybrid-Electric Aeroengines

Abstract Hybrid-electric propulsion for commercial aircraft is currently a key industry interest. Consequently, publications on its design and performance estimation are manifold. However, models addressing characteristics of maintenance, repair, and overhaul (MRO) are virtually unavailable—even though direct maintenance costs (DMC) represent a significant part of direct operating costs (DOC) in commercial aviation. Detailed analysis of hybrid-electric aircraft propulsion degradation and maintenance scenarios must integrate both methods of sizing and design as well as operational factors for conventional and electric subsystems, as operator-specific utilization strongly influences MRO. Accordingly, a holistic engine analysis model is currently being developed using the example of an Airbus A320 aircraft, taking into account flight mission, engine performance, degradation, and MRO. This paper presents an implementation of hybridization into the gas turbine thermodynamic cycle calculation for parallel hybrid-electric (PHE) engine architectures with 2 and 5 MW electric motors, and the approach necessary for resizing hybridized gas turbine components. Turbomachinery loading throughout representative short-haul missions is analyzed for conventional and hybrid-electric configurations based on the V2500 high-bypass turbofan engine, whereby unknown or uncertain boundary conditions are considered in a probabilistic sensitivity study. As a result, MRO-driving quantities such as engine performance parameters, atmospheric conditions, and ingested aerosols can be compared. The findings suggest that DMC related to the gas turbine may be considerably lowered through hybridization, as it allows for reduced peak temperatures and more uniform gas turbine operation. However, these gains are at least partially offset by additional components' DMC. For electrical machines, bearings and the stator winding insulation are life-limiting, where the latter becomes increasingly dominant for higher power densities associated with high current densities and copper losses. Thermo-mechanical stresses are considered as driving mechanisms in power electronic systems degradation. Consequently, powerful lightweight machines must be balanced against tolerable thermal and electrical loads to achieve suitable service life.

Generation of Parametric Climb Trajectories considering Operational Inputs for Aircraft Engine Thrust Extraction

For aircraft engines costs related to maintenance, repair \& overhaul make up a great proportion of the overall direct operating costs. As the aviation sector is about to face substantial technological shifts towards hybrid-electric and all-electric propulsion, tools are required to model engine operating costs and their strong interdependence to operational factors. This study presents a method for adapting the parametric climb trajectory generation of the aircraft performance model OpenAP for considering operational inputs of flight distance and ambient conditions. Flight data of Airbus A320 operated in North America are analysed for the characteristic climb parameters. The data is used to train a XGBoost machine learning model in order to link the operational inputs to the trajectory parameters. The results show, that the model is able to represent global trends in the data while staying within the limits of the original model. However, the model shows some singularities, which could be addressed by parameter tuning and expanding the data base. Eventually, the generated trajectories differ from the default trajectory of the original model, such that the average thrust per segment varies in the range of ±20% to ±10%.

Timing is everything; operational changes at a pumping station with a gravity sluice to provide safe downstream passage for silver European eels and deliver considerable financial savings

Catadromous European eel (Anguilla anguilla) are a critically endangered fish species due in part to in-river anthropogenic barriers (e.g., pumping stations, weirs, hydropower facilities). European legislation stipulates that safe downstream passage must be provided at hazardous intakes. Where present, gravity sluices have the potential to act as safe and low-cost downstream passage for seaward migrating silver eels at pumping station, but operational changes are required. This study used catchment-wide and fine-scale acoustic telemetry to investigate if operational changes (OC) at a pumping station (PS) with a co-located gravity sluice (GS) facilitated safe downstream passage for silver European eels. Specifically, night-time pump operations were ceased, river levels prior to sluicing were elevated and the GS was opened during key eel migration windows, i.e., at night during the new moon phase in autumn. No tagged eels passed through any pumps and the majority (2018 = 87.5%, 2020 = 88.9%) that approached the PS during OC passed downstream through the GS. Most eels approached during the first period of night sluicing after release (2018 = 73.9% and 2020 = 76.5%) and passed downstream during the first sluice event they experienced at the PS (2018 = 66.7% and 2020 = 75.0%). During the final approach prior to passage, very few retreats back upstream occurred at a median (IQR) distance of 34 (7.25) m from the GS and were predominantly a short distance (1–8 m). Overall, OC at a PS with a GS are considered a win-win-win, despite opening the sluice for <3% of the study period, given safe downstream passage was maximised, the financial benefits of sluicing water (∼£14,670 in direct operational costs over two years) and the relative ease of implementation.

Adaptive reinforcement learning for task scheduling in aircraft maintenance

This paper proposes using reinforcement learning (RL) to schedule maintenance tasks, which can significantly reduce direct operating costs for airlines. The approach consists of a static algorithm for long-term scheduling and an adaptive algorithm for rescheduling based on new maintenance information. To assess the performance of both approaches, three key performance indicators (KPIs) are defined: Ground Time, representing the hours an aircraft spends on the ground; Time Slack, measuring the proximity of tasks to their due dates; and Change Score, quantifying the similarity level between initial and adapted maintenance plans when new information surfaces. The results demonstrate the efficacy of RL in producing efficient maintenance plans, with the algorithms complementing each other to form a solid foundation for routine tasks and real-time responsiveness to new information. While the static algorithm performs slightly better in terms of Ground Time and Time Slack, the adaptive algorithm excels overwhelmingly in terms of Change Score, offering greater flexibility in handling new maintenance information. The proposed RL-based approach can improve the efficiency of aircraft maintenance and has the potential for further research in this area.

Introducing the Box-Wing Airframe for Hybrid-Electric Regional Aircraft: A Preliminary Impact Assessment

The combination of new airframes with electric and hybrid-electric propulsion is a potential solution to decarbonize aviation. In this context, recent studies have proven that the box-wing airframe, if integrated on a hybrid-electric aircraft belonging to the regional category, can provide significant reductions in fuel consumption. In light of these promising results, this paper aims to present a broader comparison between the box-wing aircraft and the conventional tube-and-wing aircraft, in the context of regional hybrid-electric air transport. An economic analysis is assessed, and the effects deriving from the box-wing introduction, in terms of direct operating costs, are quantitatively evaluated by applying cost models that consider the integration of hybrid-electric propulsion. In parallel, a comparative analysis of greenhouse emissions is proposed, considering both flight- and production-related emissions. The environmental, economic, and operating improvements that the introduction of the box-wing configuration may provide in the context of future regional hybrid-electric aviation are critically detailed. In this regard, the proposed results show that a box-wing hybrid-electric aircraft can reduce cost and emission without affecting compliance with current airport aprons. Finally, a general summary is presented, providing a solution that represents a practical, incremental, and technological step in the path of commercial aviation decarbonization.

Cost of treating sick young infants (0-59 days) with Possible Serious Bacterial Infection in resource-constrained outpatient primary care facilities: An insight from implementation research in two districts of Haryana and Uttar Pradesh (India).

Information on the average and incremental costs of implementing alternative strategies for treating young infants 0-59 days old in primary health facilities with signs of possible serious bacterial infection (PSBI) when a referral is not feasible is limited but valuable for policymakers. Direct activity costs were calculated for outpatient treatment of PSBI and pneumonia in two districts of India: Palwal, Haryana and Lucknow, Uttar Pradesh. These included costs of staff time and consumables for initial assessment, classification, and referrals; recommended treatment of fast breathing (oral amoxicillin for seven days) and PSBI (injection gentamicin and oral amoxicillin for seven days); and daily assessments. Indirect operational costs included staff training; staff time cost for general management, supervision, and coordination; referral transport; and communication. The average cost per young infant treated for recommended and acceptable treatment for PSBI was 16 US dollars (US$) (95% CI = US$15.4-16.3) in 2018-19 and US$18.5 in 2022 (adjusted for inflation) when all direct and indirect operational costs were considered. The average cost of recommended treatment for pneumonia was US$10.1 (95% CI = US$9.7-10.6) or US$11.7 in 2022, per treated young infant. The incremental cost 2018-2019 for supplies, medicines, and operations (excluding staff time costs) per infant treated for PSBI was US$6.1 and US$4.3 and for pneumonia was US$3.5 and US$2.2 in Palwal and Lucknow, respectively. Operation and administrative costs were 25% in Palwal and 12% in Lucknow of the total PSBI treatment costs. The average cost per live birth for treating PSBI in each population was US$5 in Palwal and US$3 in Lucknow. Higher operation costs for social mobilisation activities in Palwal led to the empowerment of families and timely care-seeking. Costs of treatment of PSBI with the recommended regimen in an outpatient setting, when a referral is not feasible, are under US$20 per treated child and must be budgeted to reduce deaths from neonatal sepsis. The investment must be made in activities that lead to successful identification, prompt care seeking, timely initiation of treatment and follow-up.

Comparative Analysis of Direct Operating Costs: Conventional vs. Hydrogen Fuel Cell 19-Seat Aircraft

In this paper, a comparative analysis of direct operating costs between a 19-seat conventional and hydrogen-powered fuel cell aircraft is performed by developing a model to estimate direct operating costs and considering the evolution of costs over time from 2030 to 2050. However, due to the technology being in its early stages of development and implementation, there are still considerable uncertainties surrounding the direct operating costs of hydrogen aircraft. To address this, the study considers high and low kerosene growth rates and optimistic and pessimistic development scenarios for hydrogen fuel cell aircraft, while also considering the evolution of costs over time. The comparative analysis uses real flight and aircraft data for the airliner Trade Air. The results show that the use of 19-seat hydrogen fuel cell aircraft for air transportation is a viable option when compared to conventional aircraft. Additionally, the study suggests potential policies and other measures that could accelerate the adoption of hydrogen fuel cell technology by considering their direct operating costs.

Design Investigation of Potential Long-Range Hydrogen Combustion Blended Wing Body Aircraft with Future Technologies

Present work investigates the potential of a long-range commercial blended wing body configuration powered by hydrogen combustion engines with future airframe and propulsion technologies. Future technologies include advanced materials, load alleviation techniques, boundary layer ingestion, and ultra-high bypass ratio engines. The hydrogen combustion configuration was compared to the configuration powered by kerosene with respect to geometric properties, performance characteristics, energy demand, equivalent CO2 emissions, and Direct Operating Costs. In addition, technology sensitivity studies were performed to assess the potential influence of each technology on the configuration. A multi-fidelity sizing methodology using low- and mid-fidelity methods for rapid configuration sizing was created to assess the configuration and perform robust analyses and multi-disciplinary optimizations. To assess potential uncertainties of the fidelity of aerodynamic analysis tools, high-fidelity aerodynamic analysis and optimization framework MACH-Aero was used for additional verification. Comparison of hydrogen and kerosene blended wing body aircraft showed a potential reduction of equivalent CO2 emission by 15% and 81% for blue and green hydrogen compared to the kerosene blended wing body and by 44% and 88% with respect to a conventional B777-300ER aircraft. Advancements in future technologies also significantly affect the geometric layout of aircraft. Boundary layer ingestion and ultra-high bypass ratio engines demonstrated the highest potential for fuel reduction, although both technologies conflict with each other. However, operating costs of hydrogen aircraft could establish a significant problem if pessimistic and base hydrogen price scenarios are achieved for blue and green hydrogen respectively. Finally, configurational problems featured by classical blended wing body aircraft are magnified for the hydrogen case due to the significant volume requirements to store hydrogen fuel.

Pengaruh Biaya Operasional Terhadap Produktivitas Kerja di PD. Baratala Tuntung Pandang Tahun 2020-2021

This study aims to determine the effect of operational costs on work productivity at PD. Baratala Tuntung Pandang in 2020-2021. The research method used is a quantitative research method with secondary data obtained from the company's quarterly profit and loss reports for 2020-2021. This research was conducted at the Baratala Tuntung Pandang Regional Company, one of the regional companies in Tanah Laut Regency. Data analysis techniques used quantitative data analysis through simple linear regression analysis, correlation coefficient analysis, and coefficient of determination analysis. The results of the correlation hypothesis test show that there is a very strong correlation between direct operational costs and work productivity with a correlation coefficient of 0.909 while the results of the indirect operational costs hypothesis test have no correlation with work productivity with a correlation coefficient of -696. Based on the results of the t test, it can be concluded that H0 is rejected and H1 is accepted, which means that operational costs directly affect work productivity in PD. Baratala Tuntung Pandang. This can be seen from the calculation of the t test where the t-count value is greater than the t-table value (5.340 2.571). In addition, direct operational costs also have a direct relationship with work productivity, so that if the value of operational costs increases, the value of work productivity will also increase.