Cost Rate Research Articles

Modeling Systems with Dependent Catastrophic and Degradation Failures Incorporating Uncertainty

This research examines the interval-valued availability and cost of a competing-risk system with dependent catastrophic and degradation failures incorporating uncertainty. Uncertainty indicates that the probability of the successful operation of the system is not precisely known. The considered system has three states: normal, degraded, and totally failed. While degradation failures lessen the system’s overall effectiveness and lead it to a degraded state, a catastrophic failure abruptly terminates the system’s operations and results in a totally failed state. The interrelationship between these two failures is illustrated by the fact that each degradation failure elevates the possibility of a catastrophic failure. To identify a failure, sequential inspections are performed on the system. If the system is found to be degraded, a minimal repair is executed. If a catastrophic failure is detected, a corrective repair is performed. By integrating the aforesaid points, a theorem describing the upper and lower limits of the model’s reliability is derived. Furthermore, some theorems defining the bounds of point availability, long-run availability, and the average long-run cost rate are established. A numerical example of an aluminum electrolytic capacitor is taken to demonstrate the results.

Multi-criteria study and machine learning optimization of a novel heat integration for combined electricity, heat, and hydrogen production: Application of biogas-fueled S-Graz plant and biogas steam reforming

The current research introduces an environmentally friendly heat design method by employing biogas fuel, aiming to yield electricity, hydrogen, and heating load simultaneously. The proposed arrangement consists of a biogas-powered S-Graz plant and a biogas steam reforming cycle. Although methane-fueled S-Graz plants for multigeneration purposes have been studied in previous studies, research on employing biogas fuel to launch a S-Graz plant and integrating a biogas steam reforming cycle with such a plant has yet to be examined. The model is simulated using the engineering equation solver software, and the study includes thermodynamic, exergoeconomic, and sustainability assessments to show the potential of the suggested configuration. By conducting a sensitivity study, a machine learning optimization method within MATLAB is implemented to exhibit the final optimal solution for the proposed arrangement. This optimization uses artificial neural networks and a non-dominated sorting genetic algorithm-II algorithm in a triple-objective framework based on energy efficiency, sustainability index, and products’ specific cost. The optimization demonstrates that the mentioned objectives reach optimal values of 58.26 %, 4.56, and 15.56 $/GJ, respectively. Also, the optimal net output power and hydrogen production rate equal 5746 kW and 1.45 m3/s, respectively. Besides, the process determines the optimal exergy efficiency, total net present value, and payback period as 52.70 %, 50.3 M$, and 8.96 years, respectively. The total investment cost rate for this system also is found to be 219.8 $/h.

Extractive Distillation of Isobutyl Alcohol and Isobutyl Acetate Using Dimethyl Sulfoxide: Process Design and Intensification

AbstractWe have designed a separation process of isobutyl alcohol (52.0 mol%) and isobutyl acetate (48.0 mol%) mixture using conventional extractive distillation (ED) and extractive dividing‐wall column (E‐DWC) with the solvent dimethyl sulfoxide (DMSO). The binary mixture exhibits a minimum boiling azeotrope that is sensitive to pressure. Thermodynamic analyses have shown that the vacuum pressures work better compared to the atmospheric pressure when DMSO is the solvent. Based on the separation with a purity of 99.9 mol%, the E‐DWC process has resulted in 9.6 % and 4.8 % reductions in the total annual cost and CO2 emission rates, respectively, in comparison to the conventional method. After further intensification using the heat pump technique, the E‐DWC process with the solvent DMSO has provided more than 40.0 % reduction in energy consumption compared to the ED systems studied in the literature using the solvents butyl propionate and dimethylformamide.

Mission reliability modeling based on extended RQR chain considering process scheme robustness for multistate manufacturing systems

Process scheme robustness is the core of the “Method” in 5M1E (Man, Machine, Material, Method, Measurement, and Environment), which is the foundation of manufacturing quality and reliability assurance. However, previous studies frequently overlooked the significant impact of the coupling between the process scheme and process parameter robustness on the formation and degradation of mission reliability. Therefore, a novel method for modeling mission reliability in a multistate manufacturing system is proposed. This method is based on an extended RQR chain (manufacturing system Reliability, operational process Quality, and the produced product Reliability) while considering process scheme robustness. First, the connotation of process scheme robustness and mission reliability in multistate manufacturing systems is described. Second, an extended RQR chain (ERQR chain) model is established, which considers the influence of process scheme robustness on the high-quality operation of the manufacturing system. Third, based on the established ERQR chain model, an integrated mission reliability model considering process scheme robustness for multistate manufacturing systems is established. Specifically, the process scheme robustness is evaluated from three perspectives: manufacturing cost, operation time, and product qualification rate. Finally, a hydraulic pump is used as an example to verify the effectiveness of the proposed approach.

Reservation and allocation model considering the user cost and the utilization of parking space

In order to alleviate the problem of imbalance between parking supply and demand by improving the utilization rate of parking resources, and considering the game relationship between user benefits and system benefits in parking allocation, the optimization objective function of maximum parking space utilization and minimum user cost in parking reservation mode is established from the two aspects which are system optimization and user optimization respectively. Then, the optimal allocation parking integer programming model (OPA) considering users' preferences is established. An Augmented Lagrangian-Alternating Direction Method of Multipliers Algorithm is designed to solve the optimal solution of the model. Finally, in order to test the validity of the model, the proposed model and the classical distribution model are compared and analyzed under different supply and demand conditions. The results show that the performance of the proposed model in three performance metrics which are parking utilization, average user cost and request acceptance rate is significantly better than that of the classical allocation model. The research results of this paper can provide theoretical reference for the management of parking reservation platform.

Innovative multi-generation system producing liquid hydrogen and oxygen: Thermo-economic analysis and optimization using machine learning optimization technique

This research investigates the multi-objective optimization of a geothermal-driven multi-generation system designed to produce liquid hydrogen and oxygen as its primary outputs. The system incorporates a Proton Exchange Membrane (PEM) Electrolyzer alongside a modified ejector-based Organic Rankine Cycle to generate the required Energy (heating bar, cooling bar, electricity and hydrogen). Case studies were conducted in three distinct locations: Zanjan in Iran, Aarhus in Denmark, and San Bernardino in the United States, utilizing actual geological and meteorological data for accuracy. Simulations were executed applied Engineering Equation Solver & optimization of the system was carried out to enhance performance by focusing on the objective functions of system exergy efficiency and cost reduction. This was accomplished by utilizing response surface methodology (RSM) along with Minitab software (MS).To optimize the system, six decision variables were identified as critical parameters influencing performance. The optimization results indicated that the system can achieve an exergy efficiency of 53.74 % while maintaining a cost rate of $31.56 per hour. The overall cost rate for the geothermal system was determined to be $54.50 per hour, with $10.10 per hour allocated to hydrogen production and $44.40 per hour to electricity generation. Site-specific analyses highlighted San Bernardino as the most favorable location for implementing this system, projecting an annual production of 90.8 tons of liquid hydrogen and 208.3 kg of oxygen. In August, the geothermal system in San Bernardino can produce up to 7691.6 kg/h of liquid hydrogen, while in December, production decreases to 7402.8 kg/h, marking the lowest output for the year. In contrast, Zanjan and Aarhus demonstrated lower production capacities, underscoring the system's feasibility as dependent on site-specific conditions.

Holistic opportunistic maintenance scheduling and routing for offshore wind farms

Despite the high growth of the offshore wind market, the economic benefits of wind energy sources are still being undermined by its high operation and maintenance expenses. On the one hand, high maintenance expenses are a direct result of offshore-specific challenges such as complex ocean meteorology, varying vessel accessibility, and shifting transportation requirements. Besides, component degradation and weather conditions largely limit the ability of turbine operators to estimate a workable maintenance time window. This study aims to develop a holistic opportunistic maintenance strategy to address the practical challenges of offshore wind farms. The proposed strategy starts by deriving the preventive maintenance interval of each turbine component based on its degradation trend and predictable cost rates. Then, each turbine is maintained in groups based on the maintenance opportunities arising from preventive maintenance, unexpected failures, and cable damage. Following that, given weather condition forecasts of key parameters (wind speed and wave height), the proposed strategy optimizes the daily allocations and vessel routes to maintain turbines in a timely and cost-effective manner. Finally, experimental results based on real-world data from an actual offshore wind farm demonstrate that the proposed strategy outperforms several universal maintenance strategies in key metrics. Compared to the simple, widely employed, and easy-to-implement strategies, it can help reduce the total cost by 85.9 %, 65.9 %, and 41.6 %, respectively. This work helps turbine operators implement comprehensive and cost-effective maintenance schemes, which can lead to tariff duction and wind farm promotion benefits in the long term.

Detection of genomic alterations in liquid biopsies from patients with non-small cell lung cancer using FoundationOne Liquid CDx: a cost-effectiveness analysis

Objective Liquid biopsy (LB) is a non-invasive technique to detect genetic alterations by next-generation sequencing (NGS) when tissue biopsy is not available. This study aims to estimate in the Spanish setting, the cost-effectiveness of using FoundationOne Liquid CDx (F1L CDx), a novel blood-derived LB test based on NGS, versus non-molecular diagnosis (non-mDx) in patients with advanced non-small cell lung cancer (NSCLC) in whom tissue sampling is not feasible. Methods A joint model was developed combining a decision-tree with partitioned survival models to calculate the costs and health outcomes over a lifetime horizon, comparing F1L CDx in LB versus non-mDx. Only direct costs (expressed in €of 2023) were included and a 3% discount rate for future costs and effects was considered. Health outcomes were expressed in Life Years (LYs) and Quality-Adjusted Life Years (QALYs). Utilities and treatment efficacy were obtained from the literature. An expert panel of 11 Spanish oncologists determined the treatment allocation and validated all model inputs and assumptions. Several sensitivity analyses were performed to assess the robustness of the results. Results In a hypothetical cohort of 1,000 patients, LB using F1L CDx would detect 386 alterations, so those patients could be treated with targeted therapies or enrolled in clinical trials. Cost-effectiveness results showed that F1L CDx provides greater effectiveness than non-mDx (+383.95 LYs and +305.94 QALYs), with an additional cost of €2,898,308. The incremental cost-utility ratio was €9,473/QALY gained. The probabilistic sensitivity analysis confirmed the robustness of the cost-effectiveness results. Limitations Various limitations inherent to cost-effectiveness analyses were described. Conclusion LB with F1L CDx test is a cost-effective strategy in Spain for patients with advanced NSCLC without tissue sample available for molecular diagnosis, improving the personalized treatment of these patients.

A geothermal-based freshwater/cooling system assisted by heat recovery sections: 3E analysis and techno-economic optimization using genetic algorithm

The proposed system uses a dual-loop organic Rankine cycle, a reverse osmosis desalination unit, an absorption cooling unit, and a thermoelectric generator to produce electricity and freshwater for urban areas. A thorough assessment of the system's thermodynamic and economic performance has been conducted, with a parameter-based investigation to assess the effect of key variables on the system performance. The parametric study indicates that rising the geothermal mass flow rate enhances the energy efficiency, but lowers the energy efficiency and affects the cooling requirements. Moreover, the optimum inlet temperature in turbine 1 increases the desalination efficiency up to 105.02 kg/s at 115 °C, and higher temperatures reduce the performance and system efficiency. Adjusting the temperature difference at the pinch point at Evaporator1 is crucial for system efficiency, with trade-offs between freshwater output, expenses, and exergy efficiency. The capability of the system to produce up to 6,048,000 L of potable water daily signifies a monumental leap towards meeting the water demands of nearly 42,000 individuals, based on European consumption standards. Lastly, the application of genetic algorithms in the optimization process results in an exergetic efficiency of 32.79 % and a cost rate of 58.05 $/h, demonstrating the system's enhanced operational effectiveness.

Opportunistic maintenance for a novel load-sharing system with dependent degradation rate and volatility

For traditional degrading load-sharing systems, a typical assumption lies in the only effect of unit load on its degradation rate. However, motivated by a laser system example with positive correlation between degradation rate and volatility, we present a novel load-sharing system with general degradation rate-volatility-load correlation. Furthermore, to take account for unit economic dependence caused by sharable maintenance set-up cost, and the window period generated by the maintenance on some unit, opportunistic maintenance (OM) strategy is introduced to offer the opportunity of simultaneously maintaining another working unit under control-limit criteria. Based on the semi-regenerative process, the long-run average cost rate is minimized to obtain the optimal inspection interval, preventive maintenance and OM thresholds. Compared to the traditional condition-based maintenance strategy separately for each unit, the effectiveness of OM strategy is validated through numerical examples and case studies, offering broad managerial insights for engineers to reduce maintenance expenses.

6909 Mortality and Readmission Rates for Inpatients with Diabetic Foot Ulcer in a Tertiary, Urban Medical Center: A Five-Year Retrospective Review

Abstract Disclosure: A. Herrera Chancay: None. R. Lopez Fanas: None. H. Tabassum: None. J. Daily: None. A. Myers: None. Background: Diabetic Foot Ulcer (DFU) is a severe complication of diabetes mellitus and is associated with high rates of morbidity and mortality. The incidence of DFUs and amputation disproportionately impact Black and Hispanic populations. DFU is also associated with a high rate of hospital readmissions and prolonged length of stay (LOS). The goal of this study was to examine 1-year mortality data, LOS and readmission rate. Methods: This study was a retrospective chart review of 1348 patients admitted to three hospitals in our system in the Bronx from 6/1/16 to 5/31/21. Data was extracted from the EPIC® electronic health records, based on the diagnoses ICD 10 codes, E10.621 and E11.622. Inclusion criteria was patients admitted with an active DFU regardless of other admission diagnosis, age 18 years or above. The index admission was defined as the first admission in our medical records within the date range. Patients were excluded if their index admission was not accessible through our EMR. Simple logistic regression and multiple logistic regression were used to analyze the association between variables of interest and mortality at index admission and at 1-year, LOS and re admissions. Results: Of the 650 eligible patients, the mean age was 59 + 13 years, 70% of patients were male, and majority were non-White (88%). Mortality was 1% during the index admission and the risk increased to 6% at 1 year after the index admission. Readmission with an active DFU from the index admission occurred in 15% of patients within 30-days, 32% of patients within 90 days, and 55% of patients within 1 year. The mean length of stay was 9 +7.5 days. Discussion: Our study in an urban region has identified high rates of mortality and costs associated with DFU, which has been reported in many settings. This patient population is high risk for poor outcomes and targeted programs are needed to reduce mortality and provide care to reduce readmissions. Future studies that explore the challenges of DFU health care and that test interventions are needed to improve DFU related health outcomes. Presentation: 6/2/2024

Development of a geothermal-driven multi-output scheme for electricity, cooling, and hydrogen production: Techno-economic assessment and genetic algorithm-based optimization

This study aims to develop an environmentally friendly multi-energy system for sustainable production of electricity, cooling and hydrogen. The study introduces a pioneering geothermal-based system, integrating an ejector refrigeration cycle, a dual-loop organic Rankine cycle, and a hydrogen production unit with proton exchange membrane electrolyzers. The study provides a thorough analysis of the system's energy and exergy performance, as well as its economic feasibility. Through sensitivity and parametric analyses, the research identifies key parameters that significantly influence system performance. The system's innovative design promises minimal environmental impact while delivering multifaceted performance: generating 1.38 MW of electricity, supplying 436 kW of cooling load, and producing 5.39 kg/h of hydrogen. In the exergy analysis, Evaporator1 is identified as the primary contributor to exergy loss, representing 34 % of the total exergy destruction. This is followed by the electrolysis unit, the condenser, and the ejector refrigeration cycle, which contribute 18 %, 14 %, and 12 %, respectively. The system achieves optimal efficiency at an organic Rankine cycle turbine1 inlet temperature of 387 K, yielding a power generation of 885.4 kW and an exergy efficiency of 26.7 %. Beyond this temperature, any further increase leads to a decline in power output due to operational disturbances. A multi-criteria optimization using genetic algorithm is applied, resulting in an optimized system with a cost rate of 18.13 $/h and an exergy efficiency of 38.96 %.

Use of benchmarking as a tool of lean production in the mechanism of cost management in an agricultural organization

The mechanism of cost management, reflecting the peculiarities of its organization at the microand macro-level, with the application of lean production principles (focus on creating value for the customer, continuous improvement, strategic orientation, loss reduction, visualization and transparency, etc.) is presented. Methodological approaches to cost rationing in the production of agricultural products, taking into account the conditions of its production (resource availability of organizations) and the level of efficiency of resource expenditure are substantiated. The novelty of the considered approach consists in the use of the tool of lean production – cost benchmarking. It allowed to calculate the reserves of growth of productive indicators of agricultural producers’ activity taking into account their provision with long-term and short-term assets, labor resources.

Thermo-economic investigation and comparative multi-objective optimization of dual-pressure evaporation ORC using binary zeotropic mixtures as working fluids for geothermal energy application

This contribution performs an energy, exergy, and exergoeconomic (3E) analysis of a dual-pressure evaporation organic Rankine cycle system employing twenty different binary zeotropic mixtures as working fluids for power production from a geothermal field. To this end, the designed system is modeled, invoking the mass and energy conservation laws and the exergy and cost balance analyses. Specific Exergy Costing (SPECO) procedure is utilized to provide practical insights into the exergoeconomic aspect of the system. Comparative optimization based on the multi-objective genetic algorithm is accomplished for each mixture in order to simultaneously maximize the exergy efficiency and minimize the total cost rate using the design variables of pressure factor in low-pressure and high-pressure stages, mixture fraction, pinch point temperature differences in low-pressure and high-pressure heat exchangers, and degree of superheat in the high-pressure heat exchanger. In this regard, the Pareto frontiers are drawn for the system with all twenty different binary zeotropic mixtures. The optimal point for each mixture is obtained via the decision-making technique of LINMAP. Subsequently, the LINMAP is re-utilized to find the preferred mixture. The optimization results suggest the R123/C2Butene (96.89/3.11) mixture for this system as the optimum working fluid, considering a trade-off between a low-cost rate of $88.0651 per hr and a high exergy efficiency of 64.07 %. Finally, the exergy flow diagram is plotted to provide the exergy flow rate and the amount of exergy destruction in each segment of the system considering the optimal working fluid. In the proposed system, exergy destruction chiefly occurs within the low-pressure preheater with a value of 1061 kW, followed by the low-pressure turbine and condenser with magnitudes of about 669 kW and 266 kW, respectively.

Economic and technical optimization of a tri-generation setup integrating a partial evaporation Rankine cycle with an ejector-based refrigeration system using different solar collectors

Three collector types, namely parabolic trough solar collector (PTSC), linear Fresnel collector (LFC), and dish collector, are employed to drive a tri-generation configuration composed of a partial evaporation Rankine cycle (PERC), a hot water production unit (HWPU), and a cascade ejector-based compression refrigeration system (ECRS) for electricity, cooling, and heating production. The ECRS is integrated with the topping PERC through an absorption refrigeration system (ARS). Moreover, the collector is indirectly connected to the system by a storage tank to increase the operating hours of the system. The performance of the system is evaluated by thermodynamic and economic analysis. The three-objective optimization result is a testament to the fact that utilizing PTSC brings about the best performance of the system. The system exergy efficiency (ηex) in the case of PTSC is 8.1 % and 24.9 % higher than in the case of LFC and dish collector, respectively. The economic performance of the system in the case of PTSC is superior to that of the dish collector. Furthermore, the PTSC case results in a relatively similar economic performance to the LFC case. The system produces power, cooling, and heating at rates of 200.8 kW, 564.9 kW, and 795.7 kW in the optimum case of utilizing PTSC, respectively. Moreover, ηex, total cost rate (C˙tot), and specific cost of tri-generation (ctri) are obtained as 11.48 %, 204.7 $h−1, and 44.91 $GJ−1, correspondingly. The results indicate that ηex of the proposed layout in the case of PTSC is superior to a comparable tri-generation configuration introduced in the field by 2.78 % points.

Outpatient Versus Inpatient Total Hip and Knee Arthroplasty in Morbidly Obese Patients

Morbidly obese patients undergoing total joint arthroplasty (TJA) face increased postoperative complications, yet studies assessing the safety of this surgery in the outpatient setting for this population are lacking. This study aimed to fill this gap by assessing the safety and benefits of outpatient TJA in morbidly obese patients. This study is a retrospective review of a commercial claims database. Based on the setting of the procedure, the patients were divided into four groups: inpatient-TKA (total knee arthroplasty), outpatient-TKA, inpatient-THA (total hip arthroplasty), and outpatient-THA. The two TKA groups were matched based on age, sex, and the Charlson comorbidity index (CCI). The THA groups were matched similarly. The 30- and 90-day medical and surgical complications were compared between these groups. There were 5,500 patients included in each of the outpatient and inpatient TKA groups, and 1,550 in each of the outpatient and inpatient THA groups RESULTS: Patients undergoing inpatient TKA had higher rates of pulmonary embolism, UTI (urinary tract infection), transfusions, ICU (intensive care unit) admissions, ED (emergency department) visits, readmissions at 30 days, surgical site infections, periprosthetic joint infection, prosthetic dislocations, and costs. As for the inpatient THA group, they had higher rates of pulmonary embolism, UTI, transfusions, ICU admissions, ED visits, and costs. It is well established that morbidly obese patients undergoing total joint arthroplasty have higher complication rates than normal-weight patients, and patients should be counseled before arthroplasty. This study highlights the safety and benefits of outpatient TJA in morbidly obese patients. However, one should note that this was done using an insurance database, in which results may differ if it was done in a public and lower socioeconomic setting. Therefore, future prospective studies are needed to confirm the findings before implementing outpatient TJA in morbidly obese patients.

Implementation strategy for launch and performance improvement of high throughput manufacturing inspection systems

Product technologies are changing rapidly in advanced automotive propulsion systems. These products are driving the need for new manufacturing processes and new inspection methods. To keep new propulsion systems affordable and ensure these new products are introduced with high quality, automotive manufacturers are seeking automated inspection solutions with low cost and near-zero error rates to inspect 100% of the items. In this paper, a progressive deployment strategy of a hybrid inspection system is presented and studied in the context of technology development and rapid deployment. It enabled us to begin with human inspection and gradually phase-in automated inspection technology, while almost never failing to identify a bad item. This strategy was applied successfully to inspect ultrasonic welds in lithium ion battery packs. At the time of this study, a 75% reduction in human inspection was achieved with prospects for further reduction. Actual results from the implementation of this strategy in production are presented. Recommendations are made regarding the most appropriate time to employ this strategy and how it could increase the use of advanced automated in-line inspection technologies.

A national cross-sectional survey on community spinal cord injury individuals profiles, health-related quality of life and support services in China: implications for healthcare and rehabilitation

BackgroundSpinal cord injury (SCI) results in severe, permanent functional changes and has become a global health priority due to its high incidence, cost, and disability rate. Current national epidemiological data on SCI in China are limited and outdated. This study aimed to provide a comprehensive, national cross-sectional investigation of SCI epidemiology in China.MethodsThis cross-sectional study included 3055 SCI participants aged 8 to 78 years, conducted from May to September 2023. Data collected encompassed demographic characteristics, employment status, etiology, years lived with disability (YLD), family structure, caregiving status, income, health insurance, paralysis type, and health-related quality of life (HRQoL). Descriptive statistics analyses were used to assess demographic and injury characteristics. Group differences were assessed using t-tests, one-way ANOVA and Chi-square tests. Significant factors were examined using multivariate regression analysis.ResultsThe majority (88.9%) of respondents were aged 15 to 59 years, with a male-to-female ratio of 2.36:1. Car accidents caused 45.4% of tetraplegia cases, falls caused 35.9% of paraplegia cases, and myelitis was the leading cause of non-traumatic SCI. Among paraplegia participants, 65.5% had complete SCI, while 53.1% of tetraplegia participants had incomplete SCI. Functional improvement was reported by 9.58% of participants. Half (50.3%) of the respondents were unemployed, and 75% had incomes below the national average. HRQoL was significantly lower in the SCI population compared to controls, mainly influenced by injury site, income, age and etiology (p < 0.05).ConclusionsSCI participants in China exhibit low HRQoL and reemployment rates. Accessible community and vocational rehabilitation programs, alongside robust public medical services, are essential for enhancing reemployment and HRQoL among SCI participants, reducing the overall disease burden.

A novel TD3 for solving multi-level imperfect maintenance optimization problem

Abstract As we all know, multi-level imperfect maintenance strategy is usually more effective than single-level maintenance strategy for the actual production machines. At the same time, in the previous multi-level maintenance strategies, the majority of maintenance models only consider the constant maintenance thresholds, while variable maintenance thresholds are usually ignored. Under these contexts, a novel multi-level imperfect maintenance model with variable preventive maintenance (PM) thresholds, variable overhaul maintenance (OM) thresholds and variable number of PMs in each OM cycle is established. In order to deal with the concerned problem, a novel twin delayed deep deterministic policy gradient (TD3) algorithm that is a kind of reinforcement learning is designed, renamed as NTD3. Finally, through numerical simulation, we can find that (1) the average improvements between the proposed maintenance strategy and other three traditional strategies in the average cost rate (ACR) are 11.50%, 595.91% and 5.16%, respectively; and (2) the average improvement between the proposed NTD3 and other random search method is 5.53%. Thus, the effectiveness of the proposed maintenance strategy and the superiority of proposed NTD3 are all demonstrated.

Multi-criteria optimization next to a comparative analysis of a polygeneration layout based on a double-stage gas turbine cycle fueled by biomass and hydrogen

The significance and advantages of utilizing renewable energy sources are widely recognized. Upon examining past studies, it was revealed that there has been a lack of research on harnessing the waste energy from double-stage gas turbines powered by biomass-hydrogen hybrid fuel for polygeneration applications. Thus, a new configuration is proposed in the study for the multi-production of electricity, cooling, heating, and potable water. In the current research, a high-pressure turbine is driven by a combustion chamber fed by a biomass gasifier. Meanwhile, a low-pressure turbine is driven by a post-combustion chamber fed by hydrogen as fuel. The heat loss of the topping gas turbine cycle is recuperated by a supercritical Brayton cycle (SBC), a steam Rankine cycle (SRC), and a water heater. The waste heat of the supercritical Brayton cycle and steam Rankine cycle is recovered through an absorption refrigeration cycle and a thermoelectric generator, respectively. Thus, the heat loss of the topping system is completely recovered. The net power output of the gas turbine cycle is considered the electricity production of the system while the output power of the SBC and SRC is utilized in a reverse osmosis desalination system to produce potable water. The investigations conducted on the system are thermodynamic and exergy-economic assessments and three-objective optimization utilizing 5 gases (i.e., CO2, CO, Nitrogen, Air, and Helium) in the SBC. The final results reveal the superiority of Helium as the supercritical gas, bringing about an exergy efficiency () of 32.11%, a total cost rate () of 103 , a payback period (PP) of 0.159 years, and a specific cost of polygeneration () of 22.03 for the system. Although the levelized cost of products of the configuration is high due to the freshwater production, of the proposed system is higher than the previous systems based on a double-stage gas turbine cycle driven by biomass and hydrogen.