Unit Power Research Articles

Feasibility assessment of a novel compressed carbon dioxide energy storage system based on 13X zeolite temperature swing adsorption: Thermodynamic and economic analysis

This paper proposes a novel compressed CO2 energy storage system based on 13X zeolite temperature swing adsorption (TSA). Based on 13X zeolite adsorption gas storage and exothermic and desorption heat storage characteristics, the system could accomplish high-density storage of low-pressure CO2 and efficient heat circulation. Evaluate the system investment by economic analysis model, and apply the law of thermodynamics to perform energy and exergy analysis. Under the design conditions, the round-trip efficiency, the efficiency of the system, the energy storage density, and the investment cost per unit power were 88.88%, 69.30%, 6.23 kWh/m3, and 1.22 k$/kW, respectively, which demonstrates that the system is strongly feasible and has broad engineering application prospects. Sensitivity analysis results suggest that adsorption temperature and desorption temperature positively and negatively affect system performance. The storage pressure and temperature have a trade-off relationship and almost opposite effect on the system. The lower pinch point temperature difference assists in improving the thermodynamic performance of the system but leads to added cost. System thermal and economic performance have a gamble relationship in the equipment efficiency dimension.

Electromagnetic pump with rotating permanent magnets operation at low inlet pressures

This study aimed to investigate the performance of an electromagnetic induction pump with rotating permanent magnets under different inlet pressure conditions. The tested cylindrical-type pump was placed in the test loop to test its parameters while pumping liquid sodium. The measurements of the pump characteristics were carried out at the different inlet pressure values. The inlet pressure was varied, changing initial overpressure in the loop's expansion tank from 0,1 to 1,75 bars. Inlet pressure influenced the cavitation occurrence in the pump channel, and thus, the maximal flow rate varied from 15,2 to 73 l/s. In addition to the pressure-flow rate characteristics, various data were collected during the experiments, such as drive unit power, vibration data, and acoustic signals. Analysis of these parameters showed a clear correlation between the inlet pressure and the apparent cavitation process in the pump channel. This study aimed to establish the operational limits for the electromagnetic induction pump with rotating permanent magnets. The results indicate that the pump can safely operate within the range of inlet pressure values of 0,6 bar and cavitation number values of 3,2.

End-to-end differentiability and tensor processing unit computing to accelerate materials’ inverse design

Numerical simulations have revolutionized material design. However, although simulations excel at mapping an input material to its output property, their direct application to inverse design has traditionally been limited by their high computing cost and lack of differentiability. Here, taking the example of the inverse design of a porous matrix featuring targeted sorption isotherm, we introduce a computational inverse design framework that addresses these challenges, by programming differentiable simulation on TensorFlow platform that leverages automated end-to-end differentiation. Thanks to its differentiability, the simulation is used to directly train a deep generative model, which outputs an optimal porous matrix based on an arbitrary input sorption isotherm curve. Importantly, this inverse design pipeline leverages the power of tensor processing units (TPU)—an emerging family of dedicated chips, which, although they are specialized in deep learning, are flexible enough for intensive scientific simulations. This approach holds promise to accelerate inverse materials design.

Parametric Analysis of the Solar-assisted Intercooled Gas Turbine and Organic Rankine Cycle for Waste Heat Recovery and Power Production

The energy consumption has gradually increased in the current context. Fossil fuels are the primary source of energy for the world’s population. Furthermore, energy derived from fossil fuels has significant disadvantages, including increased pollution and global warming. Solar energy is the fastest-growing alternative to fossil fuels among the various energy options. As a result, the focus of the present work is on the thermo-economic analysis of a hybrid solar-assisted intercooled gas turbine (GT) and organic Rankine cycle (ORC) for waste heat recovery and power production at near-zero-emissions. The work outcome and maximum efficiency of the hybrid arrangement are 1342.12 kW and 71.12% respectively at the cycle pressure ratio of 8, and 443 K entry point turbine temperature. The economic model of the integrated system depicts that the unit power production cost for the combined system has been evaluated as 1932 e per kW.

Get 28-2022 National Primary Standard for the Unit Of Average Laser Power

Get 28-2022 National Primary Standard for the Unit Of Average Laser Power

Evaluation of an association between maternal prenatal psychological stress and insulin resistance during pregnancy and postpartum

Objectives: Various physiological mechanisms counteract insulin resistance (IR) during normal pregnancy. Psychological stress is a known, independent risk factor for developing IR. Pregnancy-specific psychological stress may cause IR and increase the risk of overt diabetes. Hence, the study aims to evaluate maternal psychological stress using multiple stress markers and their association with changes in IR during pregnancy and postpartum. Materials and Methods: Anthropometric measurements such as height, weight and skinfold thickness were measured using standard techniques. The stress markers were assessed using perceived stress scales (K10 questionnaire), a physiological marker of stress (Heart rate variability [HRV] measures) and biochemical stress markers (Saliva, hair cortisol levels). IR was estimated using homeostasis model assessment-estimated IR (HOMA-IR). The association of stress markers with IR was studied among fifty healthy pregnant women during pregnancy and postpartum. Results: The psychological stress scores and saliva cortisol were significantly higher during pregnancy than postpartum (P = 0.000). A comparison of cardiac autonomic function as assessed by HRV measures shows that high frequency in normalised units (HFnu) was significantly higher during the postnatal period than in the prenatal period (P = 0.000). High frequency (HF) spectral power in absolute units was also significantly higher (P = 0.002) in the postpartum period (2612.30 ± 432.24) when compared with the prenatal period (1446.10 ± 299.15). Low frequency in normalised units (LFnu), low frequency (LF)/HF ratio was significantly higher during the prenatal period than in the postnatal period (P = 0.000). As assessed by HOMA-IR values, IR was significantly higher during the prenatal period than postpartum (P = 0.04). There was a significant positive correlation between prenatal psychological stress scores, HRV parameters (LFnu, LF/HF) and postnatal IR. Conclusion: Pregnancy is associated with higher psychological stress levels and IR than postpartum. Furthermore, the maternal cardiac autonomic marker could predict postnatal IR among healthy pregnant women.

4E analysis and tri-objective optimization of a landfill plant integrated with power-to-gas and leachate treatment

Management of waste is essential since waste production has increased drastically. Landfilling is prevalent in controlling and managing wastes, particularly municipal solid wastes. Tackling the environmental problems of landfill is the goal of this work. The outputs of the landfill are biogas and leachate, which are hazardous to the environment. This problem can be solved by using the power-to-gas system and leachate treatment plant. The leachate has the potential to produce biogas, and the CO2 in biogas can be converted to methane in the methanation unit of power to gas. For this, power-to-gas needs the electricity in the electrolyzer, which can be provided from the surplus electricity of available renewables (here solar photovoltaics and wind turbine). Energy, exergy, economic and environmental analyses are applied to the system, and tri-objective optimization by the genetic algorithm is performed to gain optimum results. The obtained exergy efficiency from the given data is 19.03%. Also, the energy efficiency, net electricity generation, methane production rate, total annual cost, and CO2 conversion are 19.51%, 4.24 MW, 176.63 kg/h, €1.8 million, and 82.42%, respectively. In the ideal point of tri-objective optimization, the exergy efficiency, total annual cost, and CO2 conversion become 26.16%, €1.31 million, and 96.57%, respectively.

Unit Transformation Graphs: Modeling Students’ Mathematics in Meeting the Cognitive Demands of Fractions Multiplication Tasks

This article introduces unit transformation graphs (UTGs) as a tool for diagramming the ways students use sequences of mental actions to solve mathematical tasks. We report findings from a study in which we identified patterns in the ways preservice elementary school teachers relied on working memory to coordinate mental actions when operating in fraction multiplication settings. UTGs account for the constraint of working memory in sequencing mental actions to solve mathematical tasks. They also explain the power of units coordinating structures in offloading demands on working memory. At the end of the article, we consider some of the research implications for these findings—specifically, ways that UTGs can lend explanatory and illustrative power to analyses of students’ mathematics.

Round Robin Tests for WWER Heat Exchange Tubes

One of the most affected components from the point of view of long-time operation of WWER reactors are heat exchanging tubes of steam generators. With the nominal tube wall thickness of 1,4 mm (WWER440) or 1,5 mm (WWER1000) only and significant consequences of many factors, such as; increasing units power output, the long-time operation, secondary water chemistry and, in some cases, mechanical impact due to dissimilar welds (DN1100) repair, steam generator tubing represents one of the most critical component significantly limiting overall lifetime of many units. New forms of degradations came into being in many of WWER unites, many of them specific for some units only. Therefore, there is a wide accepted need for applying new inspection techniques. As such, these techniques are now on the market, being partially used in some units. Pulled-out tubes from Jaslovske Bohunice units 1 and 2, with real defects, well documented from the point of view of historical eddy current results and results from last inspection, carefully stored and treated, provide the great opportunity for experimental verification of these new, state-of-the art inspection ET techniques (e.g., MRPC, X-Probe, High-speed MRPC etc.).

Load frequency control in three-area single unit power system considering non-linearities effect

Load frequency control is always a crucial aspect in delivering quality power in integrated power system. This paper proposes an optimally tuned Proportional-Integral-Derivative (PID) controller to remove frequency errors caused by unexpected load fluctuations while ensuring tie-line power exchange. Moreover, the threearea power system with non-linearities such as Generation Rate Constraint and Governor Dead Band has been investigated. For tuning the parameters of PID controller Improved Grey Wolf Optimization (IGWO) has been used. The dynamic response of optimized PID controller have been compared with the result obtained from Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Sine Cosine Algorithm (SCA).

Recent Development of Anion Exchange Membrane Fuel Cells and Performance Optimization Strategies: A Review.

Anion exchange membrane fuel cells (AEMFCs) are the most promising low-temperature fuel cells and have received extensive attention. Compared to PEMFCs, the cost per unit of power can be significantly reduced for AEMFCs because, in theory, they allow the usage of non-precious metal catalysts and low-cost cell components. Owing to the development of advanced materials and performance improvement strategies, AEMFCs have achieved new records in both initial performance and durability. However, the high performance currently achieved is contingent on certain conditions, e. g., high Pt loading, large gas flowrates, and operation in pure O2 , which are far from practical applications. Therefore, the transition to commercially relevant performance and durability is the next goal of AEMFCs. This paper reviews the performance data of H2 -fueled AEMFCs since 2010 and summarizes possible performance optimization schemes, which can provide useful insights for developing next-generation AEMFCs.

Experimental Study of the Heat Flow and Energy Consumption during Liquid Cooling Due to Radiative Heat Transfer in Winter

Radiation cooling is a passive energy saving cooling technology. The process of cooling heat transfer liquid due to the combined effect of night radiative cooling and convection of air at negative temperatures (in winter) is studied. The radiator used for cooling was built into the roof of the building. Its radiating plate was made of a steel sheet coated with zinc oxide. In it, heat dissipation was carried out both from the upper and lower sides of the radiating plate. The experimental values of the heat flux ranged from 20 to 80 W·m−2 at a temperature difference between heat transfer liquid and air from 5 to 15 °C and ambient air temperature from −17 to +5 °C. The correctness of the model for calculating the heat flux in winter conditions was confirmed. A theoretical calculation showed that, in winter, the heat flux removed by the radiator will be 15% less than the heat flux in summer. The amount of heat transferred per watt of electrical power of the refrigeration unit reached 8 W·W−1. To keep the refrigeration unit with radiative heat transfer more efficient than in a conventional vapor compression chiller, the heat transfer liquid temperature should be 6 °C above the atmospheric temperature air. The results of the study show that radiative cooling can be used in winter and may be useful for the development of energy-efficient cooling systems for various purposes (air conditioning, industrial cooling systems and fruit storage chambers).

Heart rate variability and haemodynamic function in individuals with hypertrophic cardiomyopathy.

Heart rate variability (HRV) is a measure of cardiac autonomic function. This study: (1) evaluated the differences in HRV and haemodynamic function between individuals with hypertrophic cardiomyopathy (HCM) and healthy controls, and (2) determined the relationship between HRV and haemodynamic variables in individuals with HCM. Twenty-eight individuals with HCM (n=7, females; age 54±15 years; body mass index: 29±5 kg/m2 ) and 28 matched healthy individuals (n=7 females; age 54±16 years; body mass index: 29±5 kg/m2 ) completed 5-minute HRV and haemodynamic measurements under resting (supine) conditions using bioimpedance technology. Frequency domain HRV measures (absolute and normalised low frequency power (LF), high frequency power (HF) and LF/HF ratio) and RR interval were recorded. Individuals with HCM demonstrated higher vagal activity (i.e., absolute unit of HF power (7.40±2.50 vs. 6.03±1.35 ms2 , p=0.01) but lower RR interval (914±178 vs. 1014±168 ms, p=0.03) compared to controls. Stroke volume (SV) index and cardiac index were lower in HCM compared to healthy individuals (SV, 33±9 vs. 43±7 ml‎/beat‎/m², p<0.01; cardiac index,2.33±0.42 vs. 3.57±0.82 L/min/m2 , p<0.01), but total peripheral resistance (TPR) was higher in HCM (3468±1027 vs. 2953±1050 dyn·s·m2 cm-5 , p=0.03). HF power was significantly related to SV (r=-0.46, p<0.01) and TPR (r=0.28, p<0.05) in HCM. Short-term frequency domain indices of HRV provide a feasible approach to assess autonomic function in individuals with HCM. Vagal activity, represented by HF power, is increased, and associated with peripheral resistance in individuals with HCM. This article is protected by copyright. All rights reserved.

Progress in Bioinspired Photodetectors Design for Visual Information Processing

AbstractRapid development of modern science and technology has prompted explosive growth of data volumes, especially the visual information, which brings heavy pressure on information processing and computation. The classic technical route to improve the computation power of image processing units by reducing the critical dimension of the transistors according to Moore's law gradually fails due to the physical limit of transistors’ footprint and the separated architectures. Inspired by human vision systems, retina‐like photodetectors that mimic their spatial and temporal properties have attracted widespread attention. These developed architectures enable the early data processing in‐ or near‐sensor, significantly reducing the computing power required in the back end. Herein, a comprehensive review on bioinspired photodetectors that possess the spatial and temporal properties of biological vision is provided. The properties of retina are summarized and presented first. Basic structure design and operation mechanism of those photodetectors with spatial properties of retina (including the distribution of receptive fields and the shape of the hemisphere) and temporal properties of retina (including the memory properties enabled learning and the light intensity adaptation) are reviewed thoroughly. Eventually, challenges and future perspectives are commented and provided to facilitate the rapid development of in‐ or near‐sensor computing photodetectors.

Off-design characteristics of a novel integrated system of coal-fired cogeneration unit and compressed air energy storage

The regulation range of heat-power ratio in conventional coal-fired cogeneration unit of heat and power (CHP) is limited, which makes the previous determination of electricity by heat can't meet both the heat and power load, and results in relatively low efficiency. In this paper, a new integrated system of coal-fired CHP unit with compressed air energy storage (CAES) system is studied, which can greatly adjust the heat-power ratio. During heat enhanced period (increasing heat-power ratio), CAES stores electric energy and makes the compression heat supply to the users. During power enhanced (reducing heat-power ratio), CAES discharges energy and absorbs CHP extraction heat to use in CAES expander. As the regulation of heat-power ratio is a process of variable working conditions, a detailed off-design model of the integrated system is established. The influence of the key parameters on the system off-design characteristics is revealed. The research shows that the CAES air flow rate has a great impact on the integrated system's efficiency and heat-power ratio, while the CAES chamber pressure has the least impact on the integrated system's efficiency. Under different CAES air flow rates and air chamber pressures, the fuel ratio corresponding to the highest exergy efficiency in the two periods is the same, which is about 0.92. Finally, a case study is made on the data of an industry park, which shows that the integrated system can well follow the heat and power demand with relatively high efficiency.

Design and construction of solar-powered smart garbage disposal unit

Cities with developing economies experience exhausted waste collection services, and inadequately managed and uncontrolled dumpsites; which is an ongoing challenge and many struggles due to weak institutions and rapid urbanization. The purpose of the research is to design and construct a smart garbage disposal system using a two-way power supply unit (that is, the electrical power supply unit and solar power supply unit) based on Arduino Nano that utilizes ATMEGA 328p microcontroller. Two pairs of ultrasonic sensors, the pair that faced upward detects the presence of garbage disposal agent at a close distance of (5 - 50) cm and then opens the lid while the other pair faced the inside of the container senses when the container is filled up and then closes the container until it is emptied are used.

An Advanced Switched-Capacitor Multilevel Inverter Topology With a Robust PWM Controlling Technique and Voltage Boosting Property for the Grid-Connected Renewable Energy Applications

This paper proposes an improved switched-capacitor Multilevel Inverter that utilizes fewer components. The switched capacitors are employed with the DC sources in the proposed configuration to minimize the number of DC-Links in the structure, which keeps the structure compact and combinable. Those capacitors enjoy a self-charging susceptibility with the ability to balance naturally. The suggested structure supports the expansion process to catch up with satisfactory output power levels based on a slight increase in the components count. The targeted application for this inverter involves a renewable energy system (RES) to exploit the extracted electrical power and inject it into the grid. The paper suggests a developed PWM controller to control the system’s operation. The controlling scheme has the ability to adjust the balance in the DC-Links voltages to keep generating a regular output voltage. Furthermore, it helps in extracting the maximum available power from renewable resources. Meanwhile, the controller injects the real power component into the grid, which guarantees the unit power factor operation and enhances the grid’s performance. The simulation results for both sides of RES are carried out in MATLAB/Simulink, and these results are verified experimentally through the dSPACE-1103 hardware.

Multi-objective optimization for an autonomous unmoored offshore wind energy system substructure

Autonomous unmoored floating offshore wind energy systems are an unconventional but promising technological solution to access the greatest wind resource in deep waters far offshore. This study proposes a trimaran substructure for such an autonomous unmoored system producing green hydrogen, named the Wind Trawler, which serves as both a power generation system and an energy transport vessel. Using a multi-objective optimization approach founded on the non-dominated sorting genetic algorithm (NSGA-II), the principal geometric parameters of the trimaran substructure hulls (primary hull and two symmetrically-spaced equivalent outriggers) are optimized with respect to minimization of system steel mass and minimization of the average unit power consumption per unit generation. Three discrete cases of maximum allowable overturning angle in heel (5°, 10°, and 15°) are considered. The results show that outriggers provide the majority of stability while the primary hull is most significant in influencing power performance and steel mass. Constraints of system stability and minimum outrigger draught induce a tradeoff between the outrigger waterplane area and the outrigger spacing from the primary hull. Steel mass minimization correlates with small hull spacing, shallow hull draughts, and greater outrigger proportion of the total mass. Large hull spacing, deep hull draughts, and reduced outrigger size maximizes the proportion of total mass in the streamlined primary hull, and therefore minimizes power consumption relative to generation. The effect of increasing maximum allowable overturning angle is that outrigger draught is much deeper at equal spacing from the primary hull. This induces a much greater outrigger mass and less efficient system overall, which drives up power consumption relative to generation. Ultimately, the optimum Wind Trawler substructures yield steel mass results that promise to compete with that of conventional systems, especially considering the elimination of mooring and electrical transmission subsystems. Metrics of power consumption relative to generation are unique to this type of unmoored system and thus need to be translated to conventional units of net energy production. This can be performed by considering the varying expected duration and trajectories of each operational mode.

Power Compensation Strategy and Experiment of Large Seedling Tree Planter Based on Energy Storage Flywheel

The intermittent hole-digging tree-planting machine shows a periodic short-time peak load law in planting operation, and the operation process is “idling” for small loads most of the time, leading to large torque fluctuations in the transmission system, unscientific power matching, and high energy consumption. To solve the above problems, this article proposes to use a series of energy-saving flywheels in the transmission system of the tree planting machine. On the premise of obtaining holes that meet the target young tree planting requirements, the optimal power compensation strategy for the flywheel system of the tree planting machine is studied to reduce torque fluctuations in the power transmission system, use smaller power drive units, and save energy. Firstly, the nonlinear multi-body dynamics simulation model of soil cutting by the hole-digging component is established. The boundary and contact conditions are set to simulate the power consumption of the hole-digging component at three rotating speeds. Based on the simulation results, the flywheel power compensation strategy is discussed, and the torque fluctuation of the flywheel balance system is analyzed. The results showed that the higher the speed, the greater the power consumption. The power value suddenly increased from 17.82 kW (1.28 s) to 27.93 kW (1.43 s) when the speed was 220 r/min. Then, the power value rapidly decreased, and the power consumption presented a short-term peak feature. The transmission system’s maximum input power is determined as 17.82 kW according to the various simulated power consumption characteristics. The part exceeding the power consumption is compensated by the energy storage flywheel. The total compensation energy was 2382.5 J. After the flywheel system was involved, the maximum output power of the tractor power output shaft decreased by 36.2%, and the peak torque decreased from 445.7 N·m to 285.1 N·m. The power consumption obtained from the field test and simulation was similar, but the energy required to overcome peak load was jointly provided by the flywheel and the engine. The actual input power of the power output shaft during the energy release period of the flywheel system was 18.51 kW when the rotating speed of the hole-digging component was 220 r/min, and the relative error with the simulation value was 2.43%. The measured actual speed reduction of the flywheel system was 8.9%. After installing an energy storage flywheel in the transmission system of the tree planting machine, the output power of the power unit can be stabilized. Tree planting machines can be equipped with smaller power units, which can reduce energy consumption and exhaust emissions.

Methodological approach to conducting a comparative analysis of economic systems at various stages of historical development

Comparative studies of economic systems have been gaining popularity in recent years. The existing methodology for comparing quantitative indicators of the functioning of the economies of different countries has a number of limitations. The presented article discusses methods for comparing the purchasing power of monetary units of the economies of different countries, and also analyzes the possibility of using them to carry out a comparative analysis of economic indicators and indicators of the development of industries in the USSR and modern Russia in order to develop proposals for improving the state economic and industrial policy. The analysis of methods of comparing the purchasing power of monetary units made it possible to substantiate the choice of approaches for comparing production, technological and financial and economic indicators of the development of industries in the USSR and the Russian Federation. Based on the selected approaches of comparing monetary units, the conversion coefficients for various historical periods were calculated: the USSR (from 1940 to 1990) and the Russian Federation (from 2000 to 2020).