56016 research outputs found
Sort by
Strategy to coordinate actions through a plant parameter prediction model during startup operation of a nuclear power plant
No full textThe development of automation technology to reduce human error by minimizing human intervention is accelerating with artificial intelligence and big data processing technology, even in the nuclear field. Among nuclear power plant operation modes, the startup and shutdown operations are still performed manually and thus have the potential for human error. As part of the development of an autonomous operation system for startup operation, this paper proposes an action coordinating strategy to obtain the optimal actions. The lower level of the system consists of operating blocks that are created by analyzing the operation tasks to achieve local goals through soft actor-critic algorithms. However, when multiple agents try to perform conflicting actions, a method is needed to coordinate them, and for this, an action coordination strategy was developed in this work as the upper level of the system. Three quantification methods were compared and evaluated based on the future plant state predicted by plant parameter prediction models using long short-term memory networks. Results confirmed that the optimal action to satisfy the limiting conditions for operation can be selected by coordinating the action sets. It is expected that this methodology can be generalized through future research
Efficient and Moisture-Stable Inverted Perovskite Solar Cells via n-Type Small-Molecule-Assisted Surface Treatment
Get PDFDefect states at the surface and grain boundaries of perovskite films have been known to be major determinants impairing the optoelectrical properties of perovskite films and the stability of perovskite solar cells (PeSCs). Herein, an n-type conjugated small-molecule additive based on fused-unit dithienothiophen[3,2-b]-pyrrolobenzothiadiazole-core (JY16) is developed for efficient and stable PeSCs, where JY16 possesses the same backbone as the widely used Y6 but with long-linear n-hexadecyl side chains rather than branched side chains. Upon introducing JY16 into the perovskite films, the electron-donating functional groups of JY16 passivate defect states in perovskite films and increase the grain size of perovskite films through Lewis acid-base interactions. Compared to Y6, JY16 exhibits superior charge mobility owing to its molecular packing ability and prevents decomposition of perovskite films under moisture conditions owing to their hydrophobic characteristics, improving the charge extraction ability and moisture stability of PeSCs. Consequently, the PeSC with JY16 shows a high power conversion efficiency of 21.35%, which is higher than those of the PeSC with Y6 (20.12%) and without any additive (18.12%), and outstanding moisture stability under 25% relative humidity, without encapsulation. The proposed organic semiconducting additive will prove to be crucial for achieving highly efficient and moisture stable PeSCs
Optimal intensity measures for probabilistic seismic demand models of steel moment frames
No full textSelecting an optimal ground motion intensity measure (IM) is a vital step in the earthquake fragility analysis of building structures using probabilistic seismic demand models (PSDMs). This study proposes optimal IMs among 20 considered for seismic fragility analysis of structural steel moment frames in PSDMs. Five steel frames of different heights were selected to propose optimal IMs for steel frames between 2 and 20 stories. The IMs were evaluated using two engineering demand parameters (maximum interstory and roof drifts). Two characteristics of ground motions were investigated (pulse and non-pulse). The results revealed that velocity-related parameters (Housner intensity (HI) and peak ground velocity (PGV)) and spectral pseudo-acceleration at the first natural period () tend to be optimal IMs for steel moment frames. For maximum interstory drift, HI is suggested as the optimal IM for steel frames of 2???12 stories for both types of ground motions, while PGV is suggested for steel frames from 12 to 20 stories. Under maximum roof drift, is the optimal IM for steel frames of all investigated stories subjected to either ground motion type. Peak ground acceleration, which is widely used as a ground motion IM, was observed to be unsuitable for all steel moment frames investigated in this study
Development of angle-dependent linear source approximation for three-dimensional method of characteristics transport analysis method in STREAM
No full textThis paper features the development of angle-dependent linear source (ADLS) approximation for the 2D/3D Method of Characteristics (MOC)/Diamond Differencing (DD) method and its performance analysis simulation. The ADLS MOC/DD applies the linear source approximation to two different types of sources, the sum of fission and scattering source and the angle-wise surface source appearing in the MOC/DD equation. It is demonstrated memory usage and simulation time can be reduced by increasing the source approximation order from the zeroth to the first order
Group constants generation by Monte Carlo code MCS for LWR analysis
No full textThis paper presents the generation of few-group constants using the Monte Carlo (MC) code MCS for light-water reactor (LWR) analysis. The few-group constants are fed into the conventional diffusion nodal code to perform neutronic analysis. This study investigates three methods, B1, P1, and CASMO-4E (CM), to obtain the critical spectrum for correcting the cross-section for LWR analysis. The inflow transport correction based on the PN solution is integrated into the MCS in addition to the typical outflow transport correction in the MC codes. A numerical case study comparing the two-step code MCS/PARCS and MCS standalone results is required to determine the best combination in the transport/diffusion two-step to achieve a high-fidelity LWR analysis. Numerical tests with small and large LWR cores show that the CM method combined with inflow transport correction is the most accurate for two-step code MCS/diffusion in terms of the eigenvalues and power profiles
CF-3-Terminated Side Chain Enables Efficiencies Surpassing 18.2% and 16.1% in Small- and Large-Scale Manufacturing of Organic Solar Cells
No full textMany studies have proven the significant roles of side chains far beyond being the solubilizing groups as well as the interesting merits of fluorination on pi-backbones in the intrinsic properties and device performances of organic semiconductors. Considering the integration of the two features, we herein introduce a 4,4,4-trifluorobutyl (CF3- terminated) side chain into a 2H-1,2,3-benzotriazole-core-based acceptor-donor-acceptor-donor-acceptor-type non-fullerene acceptor (NFA) named YCF3 and demonstrate its effectiveness in optoelectronic, morphological, and photovoltaic properties. Comparative experimental and theoretical studies confirmed the unique features of YCF3 (e.g., red-shifted film absorption, better absorptivity, finely adjusted energies, and higher mobility) associated with its enhanced crystalline nature, compared with its analogous NFA with an n-butyl side chain named YCH3. The best power conversion efficiency (PCE) of 18.21% is achieved in a YCF3-based binary organic solar cell (OSC) together with good heat and light stability. Moreover, a YCF3-based OSC presents a remarkable PCE of 16.11% in an inverted-structure large-area device
The effects of bike-share users' socio-demographics and trip features on the bike-transit relationships
No full textUnderstanding how bike-share interacts with public transit is vital to determining the potential benefits of bike-share on the existing urban transportation system. This study examines the effects of bike-share users' socio-demographics and trip features on whether bike-share users integrate or substitute public transit by conducting a questionnaire survey of Seoul's bike-share users. The multinomial logistic model (MLM) was used for the statistical analysis. Our results showed that the bike-share's trip purpose and perceived utility are significantly associated with the modal integration and substitution between bike-share and public transit. In particular, bike-share users are more likely to integrate with public transit when they make utilitarian trips near public transit stations. Furthermore, those who substitute public transit intended to save travel costs and exercise. The study's findings can be utilized for establishing strategies to maximize the utility of bike-share in conjunction with the public transit system
Metal???Organic Framework-Supported Catalase Delivery for Enhanced Photodynamic Therapy via Hypoxia Mitigation
No full textTumor hypoxia poses a significant challenge in photodynamic therapy (PDT), which uses molecular oxygen to produce reactive oxygen species upon light excitation of a photosensitizer. For hypoxia mitigation, an enzyme catalase (CAT) can be beneficially used to convert intracellular hydrogen peroxide to molecular oxygen, but its utility is significantly limited due to the intrinsic membrane impermeability. Herein, we present direct integration of CAT into the outer surface of unmodified metal???organic framework (MOF) nanoparticles (NPs) via supramolecular interactions for effective cellular entry of CAT and consequent enhancement of PDT. The results demonstrated that CAT-loaded MOF NPs could successfully enter hypoxic cancer cells, after which the intracellularly delivered CAT molecules became dissociated from the MOF surface to efficiently initiate the oxygen generation and PDT process along with a co-delivered photosensitizer IR780. This achievement suggests that our protein???MOF integration strategy holds great potential in biomedical studies to overcome tumor hypoxia as well as to efficiently deliver biomolecular cargos
On-site formation of silver decorated carbon as an anodeless electrode for high-energy density all-solid-state batteries
No full textAll-solid-state batteries (ASSBs) are promising alternatives to lithium-ion batteries owing to their high energy density and safety. Recent studies on "anodeless" electrodes with Li-soluble metallic materials (e.g., silver nanoparticles) and carbon materials in ASSBs have shown improvements in the energy density of these cells. However, poor dispersion between metal nanoparticles and carbon materials in anodeless electrodes leads to disproportionate electrochemical phenomena. Moreover, the dendritic growth and uneven reactions caused by these imbalances impair the life cycle of ASSB cells. To address this issue, we introduce carbon-supported silver nanoparticle-based anodeless electrodes. Ag ion complexes were thermally reduced, and the reduced silver nanoparticles were well dispersed on the carbon surface. This electrode reduces overpotential during the lithiation process with less silver and provides high-rate performance. An ASSB cell using the anodeless electrode with carbon-supported silver nanoparticles exhibits 91% capacity retention after 500 cycles. Anodeless electrode composed of Ag ion complexes and carbon black was fabricated. All-solid-state batteries with anodeless electrodes exhibited improved cyclability, highlighting the usefulness of anodeless electrodes for this emerging technology
