Desired Power Research Articles

Revisiting ether electrolytes for high-voltage sodium-ion batteries

While ether electrolytes show great potential for anode materials of sodium-ion batteries (SIBs), they are perceived to be intolerant to high voltage (4.0 V and above) and are rarely employed in cathode materials. Herein, four typical ether electrolytes are examined and the oxidative stability is demonstrated to be closely related to their solvation structures. The anion-involved solvation structure lowers the tolerance of weakly solvated electrolyte to high voltage, and the resulting inorganics-rich cathode electrolyte interphase is equipped with high resistance and friability, leading to undesired rate and cycle performance. In contras, strongly solvated electrolytes can cycle stably at a high voltage of 4.3 V with high rate performance. As a proof-of-concept, the Graphite//Na3(VOPO4)2F full cell based on G2 electrolyte (1 M NaPF6 in glyme) can deliver a high energy density of 126.3 Wh kg−1 at 61.2 W kg−1 and a desirable power density of 5424.3 W kg−1 at 65.1 Wh kg−1, providing a demonstration for the potential application of ether electrolytes in high-voltage SIBs.

Investigating the influence of the Ag and Al co-doping in ZnO electron transport layer on the performance of organic-inorganic perovskite solar cells using experimentation and SCAPS-1D simulation

The sufficient material selection of electron transport layer (ETL) enormously promises exceptional conversion efficiency from perovskite (PVT) solar cells (PSCs), which in turn give rise to their rapid establishment in world-wide photovoltaic (PV) market. Among the tactics exerted on ETLs, and thus, intensifies the adequacy of associated PSCs, the methodology of doping stands productive. Therefore, this research validates the implementation of such effectual ETLs on widely approved methyl ammonium lead triiodide (MAPbI3)–based PSCs. The work brings together two versions of zinc oxide (ZnO) ETLs: one in its pristine form, and the other is aluminum (Al) co-doped with silver (Ag) represented as Ag-AZO. The investigation launches the PV capabilities of Ag-AZO ETL against its undoped correspondent. Accordingly, the earlier part of the investigation centers on the experimental assessment of ZnO and Ag-AZO nanoparticles (NPs) affirming their material and morphological aspects. Later, the research deals with the involvement of both NPs as ETLs signifying the PV potential of MAPbI3–based PSCs through comprehensive numerical analysis. The judgements of investigation declare that MAPbI3–based PSC with Ag-AZO ETL yields a desirable power conversion efficiency (PCE) of 27.26% against 25.98% from control cell. The investigation will definitely enlighten the development of forthcoming efficient PSCs incorporated with appropriate multiple metals co-doped ETLs.

Intercalated Architecture of the Ca2A2Z5 Monolayer with High Electron Mobilities and High Power Conversion Efficiencies.

The exploration of novel two-dimensional (2D) materials with a direct band gap and high mobility has attracted huge attention due to their potential application in electronic and optoelectronic devices. Here, we propose a feasible way to construct multiatomic monolayer Ca2A2Z5 (A = Al and Ga and Z = S, Se, and Te) by first-principles calculations. Our results indicated that the energies of α1-phase Ca2A2Z5 are slightly lower than those of experimentally synthesized α3-phase-like Ca2A2Z5 monolayers with excellent structural stability. Moreover, the α1- and α3-phase Ca2A2Z5 monolayers possess not only direct band gaps but also high electron mobilities (up to ∼103 cm2 V-1 s-1), demonstrating an intriguing range of visible light absorption. Importantly, α1- and α3-phase Ca2Ga2Se5 monolayers are good donor materials, and the corresponding Ca2Ga2Se5/ZrSe2 type-II heterostructures exhibit desirable power conversion efficiencies of 22.4% and 22.9%, respectively. Our findings provide a feasible way to explore new 2D materials and offer several Ca2A2Z5 candidate monolayers for the application of high-performance solar cells.

Impact of Multidisciplinary Prehabilitation Interventions on Postoperative Hospital Length of Stay and Functional Capacity in Patients Undergoing Resection of Colorectal Cancer: A Systematic Review and Meta-analysis.

Although surgery is commonly regarded as the primary curative treatment for colorectal cancer, it could potentially be associated with postoperative morbidity and mortality. To determine the pooled effect of exercise and multidisciplinary prehabilitation interventions on postoperative hospital length of stay and functional capacity in patients undergoing resection of colorectal cancer. A systematic search was conducted in MEDLINE (via PubMed) and Web of Science databases from inception to November 2022. The original systematic search retrieved 2005 studies. After the removal of duplicates and screening by title and abstract, 77 eligible full-text documents were evaluated for final inclusion in the meta-analysis. A total of 12 randomized controlled trials, 5 nonrandomized controlled trials, and 3 uncontrolled before-and-after studies were selected. Postoperative hospital length of stay (in days) and functional capacity (assessed with the peak of oxygen consumption [VO2 peak] and 6-minute walking test) were the outcome measures. The meta-analysis was conducted on 20 studies (3805 participants). Randomized controlled trials and nonrandomized controlled trials showed significant reductions in postoperative hospital length of stay (d = -0.10, nearly 2 days) and significant incremental improvements in VO2 peak (d = 0.27) and 6-minute walking test (d = 0.31). Regarding the before-and-after studies, the pooled effect of multidisciplinary prehabilitation interventions was positively significant for VO2 peak (d = 0.29) and 6-minute walking test (d = 0.29). There was no risk of publication bias (Egger test: p > 0.05), with a score of 0.71 (0-1) on average. There was a high between-studies heterogeneity, and several outcomes did not have the required number of studies for a desirable statistical power. These findings suggest that multidisciplinary prehabilitation interventions might be effective at decreasing postoperative hospital length of stay (nearly 2 days) and improving functional capacity. PROSPERO registration number CRD42022373982.

Adaptive sequential design for phase II single-arm oncology trials: an expansion of Simon’s design

ABSTRACT Single-arm phase II trials are very common in oncology. A fixed sample trial may lack sufficient power if the true efficacy is less than the assumed one. Adaptive designs have been proposed in the literature. We propose a Simon’s design based, adaptive sequential design. Simon’s design is the most used fixed sample design for single-arm phase II oncology trials. A prominent feature of Simon’s design is that it minimizes the sample size when there is no clinically meaningful efficacy. We identify Simon’s trial as a special group sequential design. Established methods for sample size re-estimation (SSR) can be readily applied to Simon’s design. Simulations show that simply adding SSR to Simon’s design may still not provide desirable power. We propose some expansions to Simon’s design. The expanded design with SSR can provide even more power.

Fe2NiO4/FeNiS2 heterostructure-assembled hollow microtubes with numerous intimate interfaces as advanced catalyst for Zn–Air battery

An efficient electrocatalyst based on hollow-structured microtubes assembled by Fe2NiO4/FeNiS2 hetero-structured nanosheets is developed for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as two-half electrochemical reactions at air cathode of the zinc–air battery. The Fe2NiO4/FeNiS2 nanosheets with strong interaction between Fe2NiO4 and FeNiS2 at the heterointerface can tailor the electronic structure towards boosting the catalytic activity. In addition, the hollow structure effectively reduces the charge/mass transfer resistance, while providing a large surface area. Therefore, the bifunctional activity of the proposed catalyst for both the ORR and OER approaches that of the Pt/C and surpasses that of the RuO2. The zinc–air battery with our material as air–cathodic material possesses a desirable power density of 144.22 mW cm−2 and superior cycling performance of over 1,500 cycles (40 min per cycle) at high current density of 2.0 mA cm−2, outperforming almost the latest reports in the literature.

Deep reinforcement learning based dynamic pricing for demand response considering market and supply constraints

This paper presents a Reinforcement Learning (RL) approach to a price-based Demand Response (DR) program. The proposed framework manages a dynamic pricing scheme considering constraints from the supply and market side. Under these constraints, a DR Aggregator (DRA) is designed that takes advantage of a price generator function to establish a desirable power capacity through a coordination loop. Subsequently, a multi-agent system is suggested to exploit the flexibility potential of the residential sector to modify consumption patterns utilizing the relevant price policy. Specifically, electrical space heaters as flexible loads are employed to cope with the created policy by reducing energy costs while maintaining customers' comfort preferences. In addition, the developed mechanism is capable of dealing with deviations from the optimal consumption plan determined by residential agents at the beginning of the day. The DRA applies an RL method to handle such occurrences while maximizing its profits by adjusting the parameters of the price generator function at each iteration. A comparative study is also carried out for the proposed price-based DR and the RL-based DRA. The results demonstrate the efficiency of the suggested DR program to offer a power capacity that can maximize the profit of the aggregator and meet the needs of residential agents while preserving the constraints of the system.

Carbon-coated Fe3O4@cotton fiber biomass carbon for the oxygen reduction reaction in air cathode microbial fuel cells

Iron-based oxide catalysts on biomass carbon fibers can jointly use their respective advantages of chemical composition and structure to develop catalysts for the oxygen reduction reaction (ORR). In this study, carbon-coated Fe3O4@cotton fiber biomass carbon (C@Fe3O4@CFBC) was prepared as an ORR catalyst through hydrothermal growth and calcination treatment for air cathode microbial fuel cells (MFCs). The carbon coating layer enhanced the O2 adsorption energy, decreased the overpotential, and promoted surface activation of the Fe3O4 catalyst. The carbon coating layer can modulate the surface electronic structure of the Fe3O4 catalyst with C–O–Fe bonding and improve the electrical conductivity to accumulate electrons on the Fe3O4 surface to enhance the ORR performance. The CFBC supported Fe3O4 nanoparticles to prevent severe aggregation and expose more effective surface-active sites. The C@Fe3O4@CFBC catalyst achieved a high positive half-wave potential (0.801 V) and low Tafel slope (73.7 mV·dec−1) compared with the Pt/C catalyst (0.877 V and 94.3 mV·dec−1). The assembled air cathode MFCs achieved a desirable maximum power density (1059 ± 16 mW·m−2) based on 1266 ± 94 mW·m−2 of Pt/C MFC devices. This work provides a strategy for designing highly active non-precious metal catalysts for air cathode MFCs.

A Control Architecture for Regulating Voltage and Power Flows in a Networked Microgrid System

This paper presents a unique control system to regulate power exchanges and load bus voltage in a networked microgrid (NMG) system comprising AC and DC microgrids. During the islanding of a microgrid in this NMG system, load voltage and power balance can get disturbed. A control system and associated converter and inverter control methods are presented to rectify these issues. An efficient model predictive control (MPC) method, which gives a tracking error of 50% lower than a conventional proportional-integral (PI) controller, is used to control multiple inverters in the NMG system. Simulation studies are conducted to test the NMG in islanding and load change scenarios. With the help of these studies, it is verified that the MPC-controlled inverters can provide better tracking accuracy in achieving desired power flows in the NMG system.

Optimized designed [formula omitted]-shape impedance in voltage type [formula omitted]-Source inverter based on average modeling

The Z-source inverter is a desirable power converter topology for voltage source and current source converter applications, which is an exciting alternative for replacing the popular conventional type.This paper presents a novel method for designing voltage-type Z-Source inverters that are innovated based on good voltage source and DC-Link prerequisites such as its current and voltage value. This method is caused to reduce the size of the capacitor and inductor as well as the total cost of the converter, which is applicable in hybrid electric vehicle development. Z-Source inverter‘s output based on its input variables and effects has been investigated to propose to optimize the design/control method. State space equations are obtained, and its model is analyzed to illustrate how the undesired effects of these changes can be omitted or compensated. It has been used to optimize the designed parameters. A prototype experimental Z-Source inverter with a rated power of 500W and switching frequency of 20kHz is developed to demonstrate the validity of the design process. The Simulation and experimental results verify that the proposed method successfully optimizes the x-shape Impedance design.

A randomized controlled phase III study comparing surgery alone versus adjuvant nivolumab versus adjuvant S-1 for locally advanced esophageal cancer with no pathological complete response: JCOG2206 (SUNRISE Trial).

TPS417 Background: On the basis of JCOG1109, neoadjuvant chemotherapy (NAC) with Docetaxel, Cisplatin, and 5-FU (DCF) has become one of the standard treatments for locally advanced esophageal squamous cell carcinoma (LAESCC). Although the efficacy of adjuvant therapy with nivolumab after preoperative chemoradiotherapy for LAESCC has been proven by CheckMate 577, the survival benefits of adjuvant therapy after NAC remain controversial. Additionally, a single-arm phase II trial of adjuvant S-1 for LAESCC who received NAC demonstrated favorable survival outcomes and safety. Methods: Eligibility criteria include the followings: thoracic esophageal squamous cell carcinoma, adenosquamous carcinoma, or basaloid squamous cell carcinoma, reception of NAC (at most three courses of DCF or two courses of Cisplatin plus 5-FU) and a diagnosis of clinical stage I (except for T1N0), II, III, IVA (except for T4), or IVB (only supraclavicular lymph node metastasis except for T4), right thoracoabdominal esophagectomy with D2 or higher lymph node dissection, R0 resection was performed, residual pathological disease in the resected specimens [ypStage T0-4aN1-3M0, T1-4aN0M0, T0-4aNanyM1 (only supraclavicular lymph node metastasis)], aged 18-80 years, ECOG performance status 0 or 1, and adequate organ function. The primary endpoint is relapse-free survival (RFS), and the secondary endpoints are disease-free survival, overall survival, adverse events, and incremental cost-effectiveness ratio. After the confirmation of patient eligibility including pathological diagnosis, patients will be randomized (1:1:1) to either the observation alone arm, adjuvant nivolumab arm (240 mg/body every two weeks or 480 mg/bodies every four weeks for one year), or adjuvant S-1 arm (four courses of twice-daily oral S-1 for four weeks followed by two weeks of rest for 6 month, three dose levels of S-1 are set according to the patient’s body surface area (BSA), as follows: BSA < 1.25 m2, 40 mg; BSA 1.25–1.50 m2, 50 mg; BSA > 1.50 m2, 60 mg, twice a day). We assumed a three-year RFS of 60% in the observation alone arm and expected an 11% increase for the nivolumab arm and the S-1 arm (HR = 0.67). The total required sample size was calculated as 435 (145 per arm) to achieve the desired power of 70% for each pair comparison (observation alone arm vs. the nivolumab arm and observation alone arm vs. S-1 arm) with an overall one-sided alpha of 5%, an accrual period of 5.5 years, and a follow-up period of three years. The planned sample size was set at 450 patients (150 patients per arm). This trial has been registered in the Japan Registry of Clinical Trials as jRCTs031230219. This trial was initiated in July 2023, and the first patient was enrolled in September 2023. Clinical trial information: jRCTs031230219 .

Investigation of Artificial Intelligence Algorithms for MPPT of Solar Photovoltaic System

Solar energy has gained prominence as a primary renewable energy source for the generation of electricity in recent years. The maximization of power extraction from photovoltaic (PV) systems is a topic of significant interest due to the relatively low conversion efficiency of these systems. Therefore, a maximum power point tracking (MPPT) controller is essential in a PV system to achieve the desired output power. This paper implements three different MPPT controllers: sliding mode control (SMC), fuzzy logic controller (FLC), and artificial neural networks (ANNs). The performance of these controllers is evaluated on a PV system under varying irradiation and temperature conditions to analyze their ability to track the maximum power point (MPP). The results demonstrate that the SMC outperforms the FLC and ANN in terms of best performance with minimum oscillation under different operating conditions.

Bayesian sequential designs in studies with multilevel data.

In many studies in the social and behavioral sciences, the data have a multilevel structure, with subjects nested within clusters. In the design phase of such a study, the number of clusters to achieve a desired power level has to be calculated. This requires a priori estimates of the effect size and intraclass correlation coefficient. If these estimates are incorrect, the study may be under- or overpowered. This may be overcome by using a group-sequential design, where interim tests are done at various points in time of the study. Based on interim test results, a decision is made to either include additional clusters or to reject the null hypothesis and conclude the study. This contribution introduces Bayesian sequential designs as an alternative to group-sequential designs. This approach compares various hypotheses based on the support in the data for each of them. If neither hypothesis receives a sufficient degree of support, additional clusters are included in the study and the Bayes factor is recalculated. This procedure continues until one of the hypotheses receives sufficient support. This paper explains how the Bayes factor is used as a measure of support for a hypothesis and how a Bayesian sequential design is conducted. A simulation study in the setting of a two-group comparison was conducted to study the effects of the minimum and maximum number of clusters per group and the desired degree of support. It is concluded that Bayesian sequential designs are a flexible alternative to the group sequential design.

Review of: "The main advantage of two-dimensional ballistic bipolar transistor devices is their very small and desirable power- delay processing"

Review of: "The main advantage of two-dimensional ballistic bipolar transistor devices is their very small and desirable power- delay processing"

Interactions between Catalyst Layer Degradation and Liquid Water Distribution in Polymer Electrolyte Fuel Cells

Managing liquid water distribution in PEFCs is critical to desirable high power density operation and cell durability [1–3]. Degradation modes such as carbon corrosion in the cathode catalyst layer (CCL) are believed to depend on local humidification [2,4], while the distribution of liquid water may also be influenced by performance drop associated with such degradation [3]. Although some studies have shown the influence of carbon corrosion on liquid water distribution [2,3], the possible reverse effect of liquid water distribution on the CCL degradation requires further investigation.The objective of the present work is to establish a deeper understanding of the cause-and-effect interactions between CCL degradation and liquid water distribution. This is achieved experimentally by carrying out voltage-cycling accelerated stress tests (ASTs) on fuel cells which differ only in the constituent gas diffusion layers (GDLs); namely, SGL 22 BB and a proprietary Avcarb. Three-dimensional X-ray microscopy is used to observe both degradation effects and liquid water distribution at different stages of the ASTs. A relatively rapid operando two-dimensional visualization technique [5] was also used to investigate the differences in liquid water distribution between the two GDLs. The fuel cells imaged are analyzed and exhibit different liquid water distributions, whereby the Avcarb exhibits a higher liquid water condensation close to the CCL, compared to the SGL. Supported by model results, this difference in liquid water distribution is shown to be attributable to the different transport properties of the GDLs. The degradation results, such as the CCL thickness (Fig. 1) show that the Avcarb cell experiences a faster CCL degradation than the SGL cell. Furthermore, the Avcarb liquid water distribution is seen to change with increasing AST cycles in a manner indicating higher vapour phase removal. These results provide insights for GDL design consideration, showing that GDL transport properties may influence liquid water distribution at the electrode with important implications for CCL durability. Acknowledgement Funding for this research was provided by the Natural Sciences and Engineering Research Council of Canada,Ballard Power Systems, Canada Foundation for Innovation, British Columbia Knowledge Development Fund,and Canada Research Chairs.

Enhancing power control in doubly fed induction generator based wind turbines: a performance comparison of fuzzy logic and sliding mode control methods

Abstract Effective power regulation is critical for ensuring the stability and performance of Doubly Fed Induction Generator (DFIG)-based wind turbines. This study conducts a comparative study between two control methodologies: fuzzy logic control (FLC) and sliding mode control (SMC), to regulate power in DFIG-based wind turbines. The paper emphasizes the importance of power regulation in wind turbines and its impact on grid stability, presents mathematical equations governing DFIG-based wind turbine systems, encompassing machine equations, power equations, and control objectives related to power regulation. A comprehensive model of the DFIG-based wind turbine system is developed, accounting for dynamic machine behavior and grid interface considerations. The modeli ng process integrates relevant electrical and mechanical components, along with power regulation control strategies. Subsequently, FLC and SMC control methodologies are developed and implemented to regulate desired power. Detailed discussions on controller design and tuning are provided, aligning with specific power control requirements. The results highlight SMC’s effectiveness in achieving precise power regulation within DFIG-based wind turbines, showcasing its superior response characteristics. The study offers valuable insights into the advantages and trade-offs associated with each control approach, aiding researchers and practitioners in selecting the most suitable control methodology for their operational needs. In summary, this paper contributes to the field of wind turbine control systems through a comparative study of FLC and SMC controllers, focusing on regulating power in DFIG-based wind turbines. The findings demonstrate SMC’s superior performance in response, enhancing our understanding of control methodologies for optimizing wind turbine performance and grid integration in sustainable energy systems.

Design and Implementation of A LED Driver Circuit with Dimming Function without Burst Mode at Constant Switching Frequency

This paper presents a dimmable LED driver with a topology of combination of series and parallel resonant converter. In dimming operation, a variable resonant inductor controlled by a PWM signal at a low frequency, while proving DC output current approaches, switching frequency variation or conventional PWM technique is not used. The proposed technique is performed on a load that consists of 40 one-watt power LEDs connected in series. Switching frequency of circuit is kept constant at 60 kHz. According to experiments results, LEDs can be dimmed to a desired power level linearly within the range of nominal power to very low power without being in burst mode unlike of the conventional PWM technique.

Sample size planning for complex study designs: A tutorial for the mlpwr package.

A common challenge in designing empirical studies is determining an appropriate sample size. When more complex models are used, estimates of power can only be obtained using Monte Carlo simulations. In this tutorial, we introduce the R package mlpwr to perform simulation-based power analysis based on surrogate modeling. Surrogate modeling is a powerful tool in guiding the search for study design parameters that imply a desired power or meet a cost threshold (e.g., in terms of monetary cost). mlpwr can be used to search for the optimal allocation when there are multiple design parameters, e.g., when balancing the number of participants and the number of groups in multilevel modeling. At the same time, the approach can take into account the cost of each design parameter, and aims to find a cost-efficient design. We introduce the basic functionality of the package, which can be applied to a wide range of statistical models and study designs. Additionally, we provide two examples based on empirical studies for illustration: one for sample size planning when using an item response theory model, and one for assigning the number of participants and the number of countries for a study using multilevel modeling.

High-Performance Paper-Based Thermoelectric Generator from Cu2SnS3 Nanocubes and Bulk-Traced Bismuth.

Flexible paper-based thermoelectric generators (PTEGs) have drawn significant interest in recent years due to their various advantages such as flexibility, adaptability, environment friendliness, low cost, and easy fabrication process. However, the reported PTEG's output performance still lags behind the performance of other flexible devices as it is not so easy to obtain a compact film on a paper-based substrate with desirable power output with the standard thermoelectric (TE) materials that have been previously utilized. In this direction, Cu2SnS3 (CTS), an earth-abundant, ternary sulfide, can be a good choice p-type semiconductor, when paired with a suitable n-type TE material. In this article, CTS nanocubes are synthesized via a simple hot injection method and a thick film device on emery paper was prepared and optimized. Furthermore, a flexible, 20-pair PTEG is fabricated with p-type CTS legs and traced and pressed n-type bismuth legs assembled using Kapton tape that produced a significantly high output power of 2.18 μW (output power density ∼0.85 nW cm-2 K-1) for a temperature gradient of ΔT = 80 K. The TE properties are also supported by finite element simulation. The bending test conducted for the PTEG suggests device stability for up to 800 cycles with <0.05% change in the internal resistance. A proof-of-concept field-based demonstration for energy harvesting from waste heat of a motorbike exhaust is shown recovering an output power of ∼42 nW for ΔT = 20 K, corroborating the experimental and theoretical results.

High power and energy density of a wavy PCM unit embedded in a solar air heater utilizing fractional porous media

This experimental and numerical investigation presents the optimization of a wavy PCM unit to obtain high power and energy density with and without porous media for solar air heater applications at low ambient temperature (12oC≤Ta≤24oC). Hence, paraffin wax as a thermal energy storage material and wire mesh as a porous media are selected in this investigation. The effect of the fractional porous region (25%≤ψ≤100%) and porosity (94%≤ϕ≤100%) of the PCM unit is investigated to obtain desired power and energy density. The obtained numerical results revealed that the porous fraction region (ψ) of 50% and porosity (ϕ) of 96% are the optimum value in wavy PCM unit to obtain high power and energy density. As an extension of this work, the optimized thermal energy storage unit is further utilized in an impinging jet solar air heater design to obtain instant and long thermal backups and, consequently, outlet air at high temperature. The wavy PCM unit embedded impinging jet solar air heater is experimentally investigated under outdoor conditions for two cases; viz, to obtain instant and long thermal backups. To obtain instant and long thermal backups, a full day and alternative operations are conducted. Whereas, in case of alternative operation, charging of the PCM unit is only done up to the maximum sunshine hour of the day and solar air heater is operated during the night to utilize stored thermal energy at high power and energy density to deliver outlet air at high temperature for the long duration. Moreover, the experimental results revealed a maximum outlet air temperature of 59°C at 0.01 kg/s and a significant thermal energy backup up to 5 h at an outlet air temperature gain of ≥ 5°C. The economic analysis is also conducted for the solar air heater design and the operating cost is obtained as 0.02 INR/kWh at the optimum condition.