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Enhancing the performance of PbS colloidal quantum dot solar cell: A computational study on absorber crystallinity and interfacial defect engineering
Get PDFThis study utilizes the SCAPS-1D simulator to computationally investigate the effect of absorber layer crystallinity and interfacial properties on the performance of PbS colloidal quantum dot (CQD) solar cell. Crystallinity of the absorber layer is modeled by varying the defect density, while interfacial behavior is analyzed by altering the defect density at the interfaces between the electron transport layer (ETL)/PbS-TBAI, and PbS-TBAI/hole transport layer (HTL). To optimize the efficiency of the PbS-TBAI CQD solar cell, acceptor (NA) and donor doping (ND) densities were tailored in the HTL and ETL, respectively. The findings indicate that tuning these parameters is pivotal for enhancing the cell performance. Detailed analysis revealed that the cell performance is strongly influenced by the crystallinity of the PbS-TBAI absorber layer. Additionally, the results demonstrated that the ETL/PbS-TBAI interface plays a more significant role in determining cell efficiency than the PbS-TBAI/HTL interface. Moreover, optimizing the back contact metal is shown to aid in efficient hole transfer by minimizing energy losses, thereby improving overall performance. The optimized solar cell demonstrated an efficiency exceeding 19 %. These findings underscore the importance of fine-tuning key parameters to enhance the efficiency of PbS CQD solar cell.journal articl
Development of Single-frame Sprite Drawing Hardware Which Can Compose Background by High-level Synthesis
Get PDFWe are developing a hardware-oriented game library using high-level synthesis. A game screen is composed of overlapping layers of various elements. In this paper, we developed a drawing hardware that draws many sprites and composes a background layer within a single frame for a single sprite layer. Experiments were conducted on an actual machine to verify the performance and usefulness of the proposed hardware.conference pape
Incorporating Temporal Dynamics and Intricate Spatial-Temporal Dependencies for ActionFormer
Get PDFActionFormer is a Transformer architecture model to identify actions and locate their start and end times from video data. This paper optimize the ActionFormer for temporal sequential data, which incorporates our dedicated modules into Transformer-based architectures to improve its performance. Two modules, one for inertial data and another one for visual data, are developed to address the challenges of high temporal dynamics and intricate spatial-temporal dependencies in inertial and visual data, respectively. Experiments on the WEAR dataset show that our method achieves substantial improvement, with a 16.01% improvement in average mAP for inertial data and a 7.8% improvement for visual data compared to the baseline ActionFormer. Additional evaluations on benchmark datasets confirm the robustness and effectiveness of the proposed approach.conference pape
A Study on the Effectiveness of Glycerophosphocholine (α-GPC) as an e-Sports Supplement
Get PDFThis study examined the effects of oral intake of Glycerophosphocholine (α-GPC) on stress response and cognitive function in e-sports. α-GPC is a precursor of acetylcholine and is sometimes used to treat Alzheimer's disease and other dementias, but its potential effects in e-sports have not been investigated. In this study, 21 participants from university e-sports clubs and other groups were given α-GPC for 2 weeks. We measured their stress responses induced by e-sports and their performance in cognitive tasks. The results showed that the placebo increased the rate of increase in salivary amylase after e-sports, but α-GPC significantly decreased this increase. It also suppressed the increase in heart rate after e-sports. Furthermore, 1g of α-GPC significantly increased the rate of correct responses in a 3-back task, a cognitive task involving working memory, after ingestion. These results suggest that 2-week intake of α-GPC may enhance cognitive function and contribute to stress reduction and suppression of autonomic nervous system disturbances caused by e-sports. Further study is needed to determine the minimum effective intake period of the supplement.journal articl
Acquisition of Unlabeled Dataset for Human Activity Recognition
Get PDFIn the paper, we recorded the device’s IMU sensors in the setting of Human Activity Recognition task for the purpose of building the pretrained model by self-supervised learner. To use the data for self-supervised learning, we collected it without labels. Therefore, unlike typical human activity recognition datasets, no labels were assigned, and it is important to note this distinction. As a result, the cost of label collection was minimized, but the time required for data collection remained the same, even though the data was unlabeled. On the other hand, since the data was unlabeled, there was no need to go through the complex process of assigning labels or inputting labels through a smartphone, which meant that data collection could be carried out without any prior knowledge of human activity recognition. The dataset consists of data from three subjects, totaling 228 hours. We performed self-supervised learning on the model and evaluated its performance using other IMU datasets. While this data was originally collected for human activity recognition, we anticipate that the use of unlabeled data in self-supervised learning will become more common in the future. In such cases, this dataset should be suitable for tasks that use unlabeled IMU data.journal articl
Optimal solar radiation pressure-assisted transfers from halo orbits to celestial bodies using genetic algorithm
Get PDFThis study presents a solar sail trajectory design framework within the circular restricted three-body problem, focusing on transfers from halo and Lyapunov orbits around the sub-L1 region to close-proximity passes of celestial bodies, particularly the Martian atmosphere in the Sun-Mars system and the Moon in the Sun-Earth system. Using a fixed-attitude, ballistic-like transfer strategy optimized via a genetic algorithm, the study achieves close-passes while minimizing both time-of-flight and sail cone angle. Numerical simulations show that Martian atmospheric passes are achievable with minimal control effort, requiring less than 14° cone angle and under 230 days across the halo orbit family. For the Moon case, close-passes are achieved with cone angles under 10° and transfer durations around 120 days across varying initial lunar positions from the chosen halo orbit. Simulation results confirm the method’s robustness and consistency to changing initial conditions, with flexible tuning via optimization weights for the trade-off between flight time and cone angle.journal articl
A Condition-Monitoring Method of a DC-Link Capacitor in a V2X Bidirectional EV Charger
Get PDFThis letter presents a condition-monitoring method of a DC-link capacitor in a vehicle-to-everything (V2X) bidirectional electric vehicle (EV) charger. EVs have gained considerable attention because of portable energy sources, thereby resulting in the development of V2X bidirectional EV chargers. Surveys of reliability in power electronics indicare that 20-30% of converter failures are attributed to capacitors. The proposed method enables condition monitoring of DC-link capacitors for the charge or discharge output changes.journal articl
Improvement and application of variable-sensitivity force sensors using shape-memory polymer
Get PDFThis study presents a variable-sensitivity force sensor utilizing a shape-memory polymer (SMP) sheet embedded with an electric heating wire, whose stiffness fluctuates with temperature changes. Therefore, replacing the force sensor is also pointless, as both the measurement range and sensitivity can be adjusted according to the target of measurement. SMP is frequently characterized as a reversible biphasic structure including a low-temperature glassy" hard phase and a high-temperature "rubbery" soft phase. This work illustrates a sensor that measures applied force using a strain gauge affixed to a beam of SMP. Consequently, the sensitivity and measuring range of the force can be adjusted based on temperature. In our prior investigation, we assessed an arrangement where a beam is fixed at both ends. However, due to the discrepancy between the measured and predicted values, we have enhanced the design of the force sensor considered in this study to broaden its applicability. Furthermore, we have utilized this improved version to measure the compressive elastic modulus and grip force to assess its superiority. In addition, we compared the calculation method of force with or without the consideration of the viscoelasticity for the grip force measurement. The results validate that the improved sensor can also change the range of the measured force depending on the temperature. Moreover, the results confirm that the compressive elastic modulus and the grip force can be measured by the proposed sensor. The application of a transfer function model in conjunction with a viscoelastic model demonstrated that a more precise measurement of grip force could be achieved by accounting for the viscoelasticity of the SMP."journal articl
Heterogeneous amorphous structure and bioactivity in silver-doped bioactive glasses synthesized by spray drying methods
No full textIn this study, Ag-doped SiO2-CaO-P2O5 bioactive glasses (BGs) were synthesized by a spray drying method, and their atomistic structures were investigated by transmission electron microscopy, X-ray diffraction, and nuclear magnetic resonance. The constituent elements (Si, Ca, P, and O) were homogeneously distributed in the pure (non-doped) BG, but a small Ca- and P-rich layer was present on the surface. The segregation of Ca and P on the surface became more pronounced with increasing Ag concentration. The atomic pair-distribution functions extracted by nanobeam electron diffraction revealed that the Ag-doped BG particles had a heterogeneous amorphous structure: the interior and surface of the BG particles were similar to those of SiO2 and phosphate-based glasses, respectively. The addition of Ag resulted in less non-bridging oxygen, which may be due to the removal of the network modifier ion (Ca) from the SiO2 network. In vitro bioactive tests of the pure BG and Ag-doped BG particles revealed that the formation of hydroxyapatite was enhanced by Ag doping, although the amount of non-bridging oxygen decreased. This is attributed to the P- and Ca-rich surface layer, which triggers the nucleation and growth of hydroxyapatite.journal articl