Stand-alone Configuration Research Articles

Sacropelvic Fixation with Porous Fusion/Fixation Screws: A Technical Note and Retrospective Review

ObjectiveThe goal of this study was to analyze our initial experience using a novel porous fusion/fixation screw (PFFS) for pelvic fixation, and to determine our rate of screw malposition requiring intraoperative repositioning. MethodsWe reviewed 83 consecutive patients who underwent sacropelvic fixation with PFFS at our institution from 6/1/2022-6/30/2023 using intraoperative CT-based computer-assisted navigation (CAN) via an open posterior approach. Following PFFS insertion, intraoperative CT scans were obtained to assess screw positioning. Demographic data was collected, and operative reports and patient images were reviewed to determine what implants were used and if any PFFS required repositioning. Results74 patients (26M:48F) were included, and 57 (77.0%) had a prior sacroiliac joint or lumbar spine surgery. A stacked screw configuration was used in 62/74 cases (83.8%). A total of 235 PFFS were used and six (2.6%) were malpositioned. Of 88 cephalic screws placed in stacked configuration, 4 were malpositioned (4.5%); and 1/123 caudal screws were malpositioned (0.8%). One of 24 SAI screws placed in a stand-alone configuration was malpositioned (4.2%). Malpositions included four medial, one lateral, and one inferior; and all were revised intraoperatively without major sequela. ConclusionsAlthough PFFS are larger than traditional sacropelvic fixation screws, stacked SAI instrumentation can be done safely with CAN. We found a low malposition rate in our initial series of patients, the majority being the cephalad screw in a stacked configuration. This isn’t surprising, as these are placed after the caudal screws which reduces the available corridor size and increases the placement difficulty.

Nacelle modeling considerations for wind turbines using large-eddy simulations

Two setups are used to investigate differences between modeling a wind turbine nacelle by means of an actuator-line model (ALM) and a wall-model (WM) using large-eddy simulations. One advantage of the ALM is that it requires a lower mesh refinement, making it less computationally costly. In the first setup, the nacelle is in standalone configuration and the ALM results show a much lower turbulence intensity and a significantly slower wake recovery when compared to the WM cases. In the second setup, the nacelle is in a rotor-nacelle assembly configuration and many variations of the ALM are tested in order to match the results from the experiment addressed in the OC6 task phase III. Contrary to previous findings that the nacelle might affect the turbine loads, this study shows that the improved match with the experiment stems from the increased mesh refinement in the nacelle region rather than the actual presence of the nacelle. Nevertheless, the wake profiles in the near-wake show a very good agreement between the ALM and WM, regardless of the refinement in the nacelle region. These cases also show a higher wake deficit than not using any nacelle at all.

Technical and financial feasibility of a chemicals recovery and energy and water production from a dairy wastewater treatment plant

Due to the high volume of wastewater produced from dairy factories, it is necessary to integrate a water recovery process with the treatment plant. Today, bipolar membrane electrodialysis units (BMEUs) are increasingly developed for wastewater treatment and reutilizing. This article aims to develop and evaluate (technical and cost analyses) a combined BMEU/batch reverse osmosis unit (BROU) process for the recovery of chemicals and water from the dairy wastewater plant. The combined BROU/BMEU process is able to simultaneously produce water and strong base-acid, and reduce power consumption due to the injection of concentrated feed flow into the BMEU. A comprehensive comparative analysis on the performances of two combined and stand-alone BMEU configurations are developed. The proposed combined technology for dairy factory wastewater treatment is designed on a new structure and configuration that can address superior cost analysis compared to similar technologies. Further, the optimal values of permeate flux and current density as two vital and influencing parameters on the performance of the studied dairy wastewater treatment process were calculated and discussed. From the outcomes, the total cost of production in the combined configuration has been reduced by approximately 26% compared to the stand-alone configuration. Increasing the feed concentration rate using the batch reverse osmosis process for the dairy wastewater treatment process can be an ideal solution from an economic point of view. Moreover, point (current density, feed concentration rate, total unit cost) = 328.9,7,14.37\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left(328.9, 7, 14.37\\right)$$\\end{document} can be considered as an optimal point for the economic performance of the studied wastewater treatment process.

A multi-objective two-stage stochastic unit commitment model for wind and battery-integrated power systems

This paper presents a mathematical programming framework for modeling the operations of power systems with high wind power penetration and BESS, accounting for wind and power demand uncertainties. For this, we introduce a multi-objective two-stage stochastic unit commitment model aimed at constructing on/off schedules that balance operating costs and CO2 emissions. Under the realistic limitations imposed by BESS high variable operating cost, we focus on assessing and analyzing the operational impact of BESS for two different integration schemes: wind farm-coupled and stand-alone. The proposed method of solution consists in an augmented ϵ-constrained algorithm with an integrated normalized euclidean distance-based bisection routine to produce more equispaced Pareto optimal solutions. We applied the proposed framework to a modified version of the New England IEEE-39 bus test system for three disjoint cases of analysis: without BESS integration, with BESS integrated into a wind farm, and with a stand-alone BESS integrated into the grid. The results demonstrate the efficacy of the proposed framework and show substantial benefits in terms of CO2 emissions reductions, particularly in the stand-alone configuration, which, although limited in extent of use, promotes the direct injection of wind power into the grid, the decommitment of polluting thermal units, enhance the use of free or low emissions technologies, and contributes as a provider of spinning reserves.

Numerical investigations on the hydrodynamic performances of an isolated OWC and its integration with a semi-circular breakwater

The exploration of multifunctional systems to harvest wave energy has become increasingly prominent in recent research. This paper presents a comprehensive investigation into the effectiveness of utilizing a wave energy converter (WEC) not only for energy generation but also as a coastal protection measure. Among the various types of WECs, the Oscillating Water Column (OWC) stands out as particularly promising due to its inherent advantages and notable efficiency. The versatility of the OWC allows for standalone installation or integration into hybrid systems, such as combining it with breakwaters. While numerous studies have examined the integration of OWCs with Caisson-type breakwaters, research on their integration with Semi-circular breakwaters (SCBW) is scarce. This study fills this gap by utilizing the open-source computational fluid dynamics (CFD) tool, OpenFOAM, to analyze the hydrodynamic performance of an OWC embedded within an SCBW. The numerical findings are validated against existing experimental data, enabling a thorough comparative analysis between the performance of an isolated OWC and a hybrid OWC integrated with SCBW. The investigation delves into various parameters, including wave amplification factor, chamber air and water pressure, external water pressure, energy transfer efficiency from chamber water to air, and wave run-up over the SCBW face. The results conclusively demonstrate that an OWC integrated with SCBW exhibits superior hydrodynamic performance compared to standalone configurations.

High-nitrogen azotetrazole based pyrogen gas generating propellants: Aspects on synthesis, characterization, combustion characteristics and kinetics

Propellant formulations containing a novel high nitrogen azotetrazole salt viz., diammonium 5,5′-azotetrazolate (DAAzT) along with two different binders viz., hydroxyl terminated polybutadiene (HTPB) and glycidyl azide polymer (GAP) were realized as potential pyrogen-based gas generators for use in inflatable structures. The DAAzT-GAP and DAAzT-HTPB propellant systems were investigated for their gas generating capabilities and it was found that the GAP based system offers enhanced gas yield of ∼430 mL/g against ∼320 mL/g for the HTPB based propellant at standard operating pressure of 1 bar and temperature of 298 K. Combustion product analyses of the propellant were undertaken by pyro GC–MS and it was found that the combustion products are benign and constitutes 62% and 53% N2 (mass fraction) as major combustion products from GAP and HTPB propellant respectively. A detailed thermal analysis of DAAzT by isoconversional method of Vzayovkin was undertaken and the dependence of activation energy with conversion was evaluated. The activation energy was also determined using a classical Kissinger method. The impact and friction sensitivity of the promising GAP-DAAzT propellant was found to be 3 Nm and 360 N respectively and the auto ignition temperature is 177.0 °C. Functional evaluation and gas generating capability of DAAzT-GAP propellant were successfully demonstrated in a sub-scale inflation test in a stand-alone configuration.

Optimal design and techno-economic analysis of hybrid renewable energy systems: A case study of Thala city, Tunisia

ABSTRACT This study explores the techno-economic feasibility of, both off-grid and on-grid, hybrid renewable energy systems for remote rural electrification in Thala City, located in the highest region of Tunisia, using wind and biomass resources. Employing Hybrid Optimization of Multiple Energy Resources based on different scenarios includes grid-connected and stand-alone configurations with pumped storage hydropower and lead acid battery storage while minimizing the levelized cost of energy, the net present cost, and greenhouse gas emissions. The optimal configuration wind/biomass/pumped-hydro storage/Converter grid-connected, minimizes the levelized cost of energy (LCOE) and net present cost (NPC), resulting in a cost of 501,540 US$ and LCOE of 0.042 US$/kWh. Notably, 7% of electricity is generated from olive mill waste, 69% from wind turbines, and 24% is purchased from the grid. This hybrid system emits 342 tons/year of CO2, 76% less than a grid-alone system, contributing to an annual CO2 reduction of 1000 tons.

A new exploration on passive control of transonic flow over a backward-facing step

PurposeThis paper aims to study passive control techniques for transonic flow over a backward-facing step (BFS) using square-lobed trailing edges. The study investigates the efficacy of upward and downward lobe patterns, different lobe widths and deflection angles on flow separation, aiming for a deeper understanding of the flow physics behind the passive flow control system.Design/methodology/approachLarge Eddy Simulation and Reynolds-averaged Navier–Stokes were used to evaluate the results of the study. The research explores the impact of upward and downward patterns of lobes on flow separation through the effects of different lobe widths and deflection angles. Numerical methods are used to analyse the behaviour of transonic flow over BFS and compared it to existing experimental results.FindingsThe square-lobed trailing edges significantly enhance the reduction of mean reattachment length by up to 80%. At Ma = 0.8, the up-downward configuration demonstrates increased effectiveness in reducing the root mean square of pressure fluctuations at a proximity of 5-step height in the wake region, with a reduction of 50%, while the flat-downward configuration proves to be more efficient in reducing the root mean square of pressure fluctuations at a proximity of 1-step height in the near wake region, achieving a reduction of 71%. Furthermore, the study shows that the up-downward configuration triggers early spanwise velocity fluctuations, whereas the standalone flat-downward configuration displays less intense crosswise velocity fluctuations within the wake region.Practical implicationsThe findings demonstrate the effectiveness of square-lobed trailing edges as passive control techniques, showing significant implications for improving efficiency, performance and safety of the design in aerospace and industrial systems.Originality/valueThis paper demonstrates that the square-lobed trailing edges are effective in reducing the mean reattachment length and pressure fluctuations in transonic conditions. The study evaluates the efficacy of different configurations, deflection angles and lobe widths on flow and provides insights into the flow physics of passive flow control systems.

Model-based fault detection in photovoltaic systems: A comprehensive review and avenues for enhancement

Solar photovoltaic (PV) systems have become a vital renewable energy source, witnessing rapid global demand. Nevertheless, these systems are susceptible to faults and anomalies that can deteriorate performance and yield significant consequences. Hence, this paper is dedicated to reviewing recent advancements in monitoring, modeling, and fault detection methods for PV systems. It encompasses diverse PV system types, including grid-connected, stand-alone, and hybrid configurations, and delves into the latest data acquisition and monitoring techniques. The review also discusses various performance modeling approaches, including empirical, analytical, and numerical models, highlighting the significance of model validation and calibration. Furthermore, it provides a comprehensive analysis of model-based fault detection techniques. Overall, this paper underscores the pivotal role of fault detection in PV systems and offers a thorough comprehension of available techniques vital for enhancing system management and maintenance.

Control and simulation of a stand-alone wind-hydrogen generation system

The potential to produce hydrogen from renewable resources is of considerable interest due to fears over man-made climate change and resource depletion. Hydrogen produced from renewable resources can be used to generate electricity through a fuel cell, or for other uses in a hydrogen economy. There are a number of potential system configurations for hydrogen production from electrolysis including grid connected and stand alone. In remote locations, stand-alone configurations are of interest, and may prove more economically viable than grid connected systems. In this paper a standalone wind - hydrogen generation system is designed and proposed to take advantage of an electrolyser capable of operating at very low power levels. A dynamic model of the system is presented, along with a maximum power point (MPPT) control algorithm of the system. The potential yield of such a wind-hydrogen stand-alone system located at the University of Glamorgan’s Hydrogen Centre is investigated using wind speed data collected at the site and the performance of the system under variable wind conditions determined.

CFD modeling of Wind-Driven Rain (WDR) on a mid-rise building in an urban area

Wind-Driven Rain (WDR) loading on building facades is a crucial factor for designing sustainable and climate-resilient buildings and preserving historical buildings. WDR loading on buildings has been studied previously but results for such a multi-parameter problem are not generally conclusive. Thus, the relevant provisions of ISO semi-empirical model cannot be applied with confidence for complex building configurations, such as those in urban areas given that the estimated WDR can be more than twice of the field measurements. This paper aims to evaluate the effectiveness of two WDR techniques, namely Lagrangian Particle Tracking (LPT) and Eulerian Multiphase (EM), combined with the steady-state standard k-ω RANS turbulence model (referred to as RANS-LPT and RANS-EM). The results obtained from the RANS-EM approach are compared with the RANS-LPT results reported in the literature for a six-story mid-rise residential building located in Vancouver, Canada. The study considers 13 distinct rainfall events, including stand-alone and urban area configurations with and without overhangs. The RANS-EM and RANS-LPT approaches are evaluated by comparing modeled wind and WDR against wind-tunnel and on-site WDR measurements, respectively. The study found that the RANS-EM requires less computational time and provides more accurate results for the test building situated in an urban area compared to the RANS-LPT.

Assessment of wind-driven rain (WDR) on buildings in an urban area: comparison of different CFD frameworks

The study of Wind-Driven Rain (WDR) loading on building facades is essential to design more sustainable and climate-resilient buildings, as well as to prevent further damage to old and historical buildings. Both WDR loading on buildings and façade responses to impinging raindrops have been studied previously but results for such a multi-parameter problem are not generally conclusive. Thus, the relevant provisions of ISO semi-empirical model cannot be applied with confidence for complex building configurations, such as those in urban areas since the WDR prediction can be more than twice that of the experimental data. In this paper, the Eulerian Multiphase (ME) technique is coupled with the RANS model to simulate the WDR loading on a six-story building under steady rainfall event conditions. Wind and WDR results are compared with the available wind-tunnel and on-site field measurement results, respectively. The field measurements were carried out on a six-story mid-rise residential building, located in Vancouver, Canada. The results show that the Euler-Euler framework (RANS-EM) predicts wind and WDR in such an urban area configuration more rapidly and accurately compared to the more traditional Euler-Lagrange framework (RANS-LPT) for both stand-alone and urban area configurations.

An Optimal Stand-Alone Power Microgrid Configuration for Rural Electrification in Mexico

In this paper, a hybrid wind-solar microgrid with battery storage aimed to bolstering remote and rural economies in Mexico (Alamos, Sonora and Petatlan, Guerrero) is presented. A load demand profile based on local economic activities is proposed and the optimal system sizing is obtained using a genetic algorithm (GA) and particle swarm optimization (PSO), both programmed in MATLAB, minimizing the global cost, and analyzing the cost of energy. The results are compared with a grid extension showing that schemes are feasible, since they present good stability and a lower cost than the extension of distributed networks.

Maximizing Returns and Minimizing Risks in Hybrid Renewable Energy Systems: A Stochastic Discounted Cash Flow Analysis of Wind and Photovoltaic Systems in Brazil

The use of renewable energy sources has become strategic in the production of electricity worldwide due to global efforts to increase energy efficiency and achieve a net zero carbon footprint. Hybrid systems can maximize stability and reduce costs by combining multiple energy sources. A conventional metric, such as the levelized cost of energy (LCOE), that is appropriate for assessing the cost-effectiveness of an option may not be appropriate when evaluating the economic feasibility of hybrid systems. This study proposes a stochastic discounted cash flow model (DCF) to assess the economic viability of a hybrid renewable energy system (HRES) in Brazil. The objective is to determine the combinations that will provide the highest 50th percentile internal rate of return (IRR) and the lowest coefficient of variation (CV). Model variables include capital expenditures (CAPEX), operation and maintenance (O&M) costs, sectoral charges, taxes, and long-term energy production metrics. The results demonstrate that the synergies modeled contributed to the higher economic outcomes for the HRES obtained by combining both energy sources rather than opting for a stand-alone configuration. A wind-dominant combination of 60% wind was able to increase the 50th percentile of the IRR, while a solar-dominant combination of 65% solar minimized the CV.

Efficiency assessments of a compound cooling system for low-humidity applications

Present work introduces the utilization of a concentric vertical pipe heat exchanger for indirect evaporative cooling. The device is coupled to a heat pump cooler, i.e., vapour compression cycle, as a pre-cooler and pre-dehumidifier of outdoor fresh air, to reduce the cooling load exerted on the evaporator. The proposed configuration borrows concepts from cooling tower operation, which enables the recirculation of room exhaust air, stabilizing its temperature before purging, also reducing the thermal load exerted over the condenser. An experimental analysis of the setup was performed, obtaining an average temperature drop, between intake and exhaust, of ∼ 10 °C. Against standalone configuration, this resulted in a 19%, and 29%, decrease of the cooling load, and required electrical input, respectively. Moreover, the inclusion of the indirect evaporative cooling setup reduced operation time by ∼ 40%; from 36 to ∼ 18 min per hour, resulting in long-term economic savings between 41 and 44% against stock energy consumption. Based on the surplus of energy achieved, this paper conducts a redesign and optimization of the heat exchangers. Through an inverse heat transfer approach, the device footprint can be reduced between 35.8 and 38.9% in terms of its weight, and 45.5 to 44.4% in terms of its surface area; features particularly useful when it comes to limitations in structural load capacity and/or space availability. The conducted redimensioning analysis revealed initial investment savings, between 36.2 and 39.7% of total cost, which albeit lower than operational-related savings, are still comparable when it comes to the design and operation of an air handling unit. Based on obtained results, the integration of the proposed setup does enhance the performance of the stock heat pump cooler, without increasing overall energy expenditure costs, thus is presented as an affordable, retrofittable, option for air conditioning systems operating in arid and semi-arid climates.

Deep-Learning-Assisted IoT-Based RIS for Cooperative Communications

Reconfigurable intelligent surfaces (RISs) are software-controlled passive devices that can be used as relay (R) systems to reflect incoming signals from a source (S) to a destination (D) in a cooperative manner with optimum signal strength to improve the performance of wireless communication networks. The configurability and flexibility of an RIS deployed in an Internet-of-Things (IoT)-based network can enable network designers to devise stand-alone or cooperative configurations that have considerable advantages over conventional networks. In this paper, two new deep neural network (DNN)-assisted cooperative RIS models, namely, DNNR-CRIS and DNNR,D-CRIS, are proposed for cooperative communications. In DNNR-CRIS model, the potential of RIS deployment as an IoT-based relay element in a next-generation cooperative network is investigated using deep learning (DL) techniques for RIS phase optimization. In addition, to reduce the maximum likelihood (ML) complexity at D, a new DNN-based symbol detection method is presented with the DNNR,D-CRIS model combined with DNN-assisted phase optimization. For a different number of relays and receiver configurations, the bit error rate (BER) performance results of the proposed DNNR-CRIS and DNNR,D-CRIS models and traditional cooperative RIS (CRIS) scheme (without a DNN) are presented for a multi-relay cooperative communication scenario with path loss effects. It is revealed that the proposed DNN-based models show promising results in terms of BER, even in high-noise environments with low system complexity.

English

Communal solar-powered irrigation systems (SPIS) have the potential for sharing the upfront costs hence encouraging farmers to adopt irrigation. Conventional methods of sizing photovoltaic water pumping (PVWP) system for irrigation consider the hydraulic energy requirement by the pump and PV generator capacity separately from the available water source capacity. As a result, the potential of the technology is not optimized, leading to over or under-sizing of the system. Consequently, there is a negative impact on acquisition cost and system performance. The study aimed to determine the optimal PVWP system configuration for communal irrigation. A comparative techno-economic and environmental performance assessment was conducted on different pumping system configurations and a multi-criteria decision analysis approach was used to select the optimal configuration. The findings show a PVWP system with storage tank as the optimal configuration for the communal irrigation. Although the initial capital cost for standalone PVWP system configurations is almost two times that of the conventional diesel pumping systems (CPS), its operation and maintenance (O&M) and lifecycle cost are respectively three times and about four times lower than the CPS cost. Furthermore, the PVWP system for communal irrigation is feasible for irrigation projects that exceed 3 years due to their high acquisition costs. Therefore, promotion of solar-powered irrigation should also focus on the communal approach as a way of improving technology adoption and upscaling. Key words: Communal irrigation system, photovoltaic water pumping system, solar powered irrigation system, design optimization.

Life cycle assessment of a novel strategy based on hydrothermal carbonization for nutrient and energy recovery from food waste

In this work, a novel strategy for food waste valorization was evaluated from an environmental life-cycle perspective. A system based on acid-assisted hydrothermal carbonization of food waste combined with the exploitation of hydrochar by combustion and process water through nutrient recovery stage and subsequent anaerobic digestion, was assessed and compared with stand-alone anaerobic digestion as the reference system. This combination of processes aims to recover both nutrients in a stage of struvite precipitation from process water and energy through hydrochar and biogas combustion. Both systems were modeled in Aspen Plus® to identify and quantify their most relevant input and output flows and subsequently evaluate their environmental performance through the life cycle assessment methodology. The novel combined system was found to generally involve a more favorable environmental performance than the reference stand-alone configuration, which would be closely linked to the substitution of hydrochar for fossil fuels. In addition, the impacts associated with soil application of the struvite produced in the integrated process would also be reduced compared to the use of the digestate generated in the stand-alone anaerobic digestion process. Following these results and the evolving regulatory framework for biomass waste management, mainly in the field of nutrient recovery, combined process based on acid-assisted hydrothermal treatment plus nutrient recovery stage and anaerobic digestion is concluded to be a promising circular economy concept for food waste valorization.

Halide Composition Engineered a Non-Toxic Perovskite–Silicon Tandem Solar Cell with 30.7% Conversion Efficiency

Since the conversion efficiency of silicon (Si)-based solar cells stagnates at 26.7% in the literature, extensive research and development activities are carried out on perovskite silicon-based tandem solar cells. However, the presence of lead (Pb) and the instability of perovskite prevent their large-scale implementation in the photovoltaic industry. Therefore, it is important to replace the hazardous material (Pb) in perovskite top cells to design non-toxic perovskite–silicon tandem solar cells. The current work yields much-needed studies to develop a non-toxic perovskite–silicon-based tandem solar cell. For the first time, methylammonium tin mixed halide (MASnI3–xBrx)-based materials are comprehensively investigated and optimized with respect to different halide compositions, absorber layer thickness, and bulk defect density in standalone configurations, followed by the development of a lead-free MASnI2Br1–Si-based tandem solar cell. The transfer matrix method and current matching techniques are used to design the two-terminal monolithic tandem cell, which showed a maximum conversion efficiency of 30.7% with an open circuit voltage (VOC) of 2.14 V. The results outlined in this manuscript will pave the way for the progress of highly efficient, non-toxic perovskite–silicon tandem solar cells.

Evaluation of a hybrid solar power system as a potential replacement for urban residential and medical economic activity areas in southern Nigeria

<abstract> <p>A hybrid solar power system (HSPS) is an alternate method of supplying electricity that can reduce fuel usage while maintaining power supply security. In this study, the efficiency of HSPS, which consists of Grid Supply (GS), Diesel Power Generation (DPG), Solar-Photovoltaic (SPV), and Battery Storage (BS) systems, was evaluated in two economic activity areas (EAAs) in Southern Nigeria. The cross-sectional research design was used, and the research was based on Behera's energy-led growth theory. Urban-residential and Health were the EAAs considered and chosen using a stratified random sample technique. Southern Nigerian states of Oyo and Lagos provided the samples, which were combined and used for the study. Electricity consumption was calculated using electricity load demand for the two EAAs from 2008 to 2017. For each EAA, an Integrated Renewable Energy Mini/Microgrid Model (IREMMM) based on power load demand and solar irradiation was constructed. Levelized Cost of Electricity (LCOE) (/kWh), and Net Present Cost (NPC) (M) were calculated for one hybrid configuration, SPV-DPG-BS-GS, and two standalone configurations, DPG and SPV-BS. Configurations with SPV integrated had lower LCOEs than DPGs in both EAAs. In Southern Nigeria, solar PV combinations with battery storage provided the highest performance for a hybrid power system. In the medical contexts, a hybrid power system achieves higher overall performance.</p> </abstract>