56016 research outputs found
Sort by
Microwell device for isolation of single polyaneuploid cancer cells (PACCs) and originated EV profiling
No full textHuman Perception on Social Robot???s Face and Color Expression Using Computational Emotion Model
No full text
Shear strength determining mechanism of a +/???45 laminate under tensile loading
No full textThe shear strength of a composite material is determined as a result of a complex damage and failure process, but the detailed progression has not been clearly elucidated. Here, the mechanism of determining the strength of a ??45 laminate under tensile loading is revealed from exquisitely designed experiments in conjunction with high- fidelity numerical simulation. Synchrotron radiation computed tomography is employed for extremely high- resolution images of damage status inside the composite just before its catastrophic failure. The ex situ observations discover the unique and consistent failure progression; one major matrix crack is initiated either in the +45 or 45 layer and delamination follows after the initial crack completely grows along both the fiber and transverse directions. After the delamination failure is triggered, remaining intact layers start to fail with multiple transverse matrix cracks. The failure of the intact layers is represented as a load drop in the global stress???strain curve. This sequential and interactive failure progression determines the shear strength of the ??45 laminate. The numerical analysis finds that the location of the initial matrix crack is dependent on the microstructure. Once the matrix crack is initiated, the numerical simulation exactly reproduces the experimentally observed failure process
Exploring stimuli-responsive elastin-like polypeptide for biomedicine and beyond: potential application as programmable soft actuators
No full textWith the emergence of soft robotics, there is a growing need to develop actuator systems that are lightweight, mechanically compliant, stimuli-responsive, and readily programmable for precise and intelligent operation. Therefore, ???smart??? polymeric materials that can precisely change their physicomechanical properties in response to various external stimuli (e.g., pH, temperature, electromagnetic force) are increasingly investigated. Many different types of polymers demonstrating stimuli-responsiveness and shape memory effect have been developed over the years, but their focus has been mostly placed on controlling their mechanical properties. In order to impart complexity in actuation systems, there is a concerted effort to implement additional desired functionalities. For this purpose, elastin-like polypeptide (ELP), a class of genetically-engineered thermoresponsive polypeptides that have been mostly utilized for biomedical applications, is being increasingly investigated for stimuli-responsive actuation. Herein, unique characteristics and biomedical applications of ELP, and recent progress on utilizing ELP for programmable actuation are introduced
Improving Hand Gesture Recognition via Infrared Tomography of the Wrist over Multiple Wearing Sessions
No full textSmartwatches now enable a wide range of end user applications. However, despite their increasingly sophisticated capabilities, the bandwidth of the user input that they support remains strongly limited by the small size of their touch screens. Numerous techniques have been proposed to improve this situation by integrating novel sensing systems and input modalities. A prominent approach here has been to detect gestures made by the hand wearing the watch with sensors capable of imaging either the associated distortions to the surface of the wrist, or changes to the wrist???s internal structures. While performance of such systems is promising (e.g., gesture accuracy of up to 93.3%), most studies currently examine performance during single studies and sessions. As such they fail to take account of the variability in measurement of wrist shapes and/or structures that might result from minor changes in sensor placement each time a device is donned. To explore the impact of this type of natural variability, we conducted a study using a watch strap prototype implementing infrared tomography to image the surface of the wrist during hand gesture production. While recognition performance during a single session of wearing this device was high (92.1%), it dropped substantially when the device was removed and re-worn between training and testing (to 22.9%). To alleviate this problem, we explore whether calibration processes that seek to maximize the consistency of sensor placements can yield improved performance. A study studies achieves this via IMU-based measurement of sensor placement similarity between sessions and shows greatly improved inter-session performance (up to 86.7%). Based on this result, we suggest that IMU based calibration of sensor placement can improve the real-world performance of gesture input systems based on wrist imaging techniques. ?? 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG
Intention-Conditioned Long-Term Human Egocentric Action Anticipation
No full textTo anticipate how a person would act in the future, it is essential to understand the human intention since it guides the subject towards a certain action. In this paper, we propose a hierarchical architecture which assumes a sequence of human action (low-level) can be driven from the human intention (high-level). Based on this, we deal with long-term action anticipation task in egocentric videos. Our framework first extracts this low- and high-level human information over the observed human actions in a video through a Hierarchical Multi-task Multi-Layer Perceptrons Mixer (H3M). Then, we constrain the uncertainty of the future through an Intention-Conditioned Variational Auto-Encoder (I-CVAE) that generates multiple stable predictions of the next actions that the observed human might perform. By leveraging human intention as high-level information, we claim that our model is able to anticipate more time-consistent actions in the long-term, thus improving the results over the baseline in Ego4D dataset. This work results in the state-of-the-art for Long-Term Anticipation (LTA) task in Ego4D by providing more plausible anticipated sequences, improving the anticipation scores of nouns and actions. Our work ranked first in both CVPR@2022 and ECCV@2022 Ego4D LTA Challenge
First-time comparison between NO2 vertical columns from Geostationary Environmental Monitoring Spectrometer (GEMS) and Pandora measurements
No full textThe Geostationary Environmental Monitoring Spectrometer (GEMS) is a UV-visible (UV-Vis) spectrometer on board the GEO-KOMPSAT-2B (Geostationary Korea Multi-Purpose Satellite 2B) satellite launched into a geostationary orbit in February 2020. To evaluate the GEMS NO2 total column data, a comparison was carried out using the NO2 vertical column density (VCD) that measured direct sunlight using the Pandora spectrometer system at four sites in Seosan, South Korea, from November 2020 to January 2021. Correlation coefficients between GEMS and Pandora NO2 data at four sites ranged from 0.35 to 0.48, with root mean square errors (RMSEs) from 4 :7 x 10(15) to 5 :5 x 10(15) molec. cm(-2) for a cloud fraction (CF) < 0 :7. Higher correlation coefficients of 0.62-0.78 with lower RMSEs from 3 :3 x 10(15) to 5 :0 x 10(15) molec. cm(-2) were found with CF < 0 :3, indicating the higher sensitivity of GEMS to atmospheric NO2 in less cloudy conditions. Overall, the GEMS NO2 total column data tended to be lower than the Pandora data, owing to differences in the representative spatial coverage, with a large negative bias under high CF conditions. With a correction for horizontal representativeness in the Pandora measurement coverage, correlation coefficients ranging from 0.69 to 0.81, with RMSEs from 3 :2 x 10(15) to 4 :9 x 10(15) molec. cm(-2), were achieved for CF < 0 :3, showing a better correlation with the correction than without the correction
Quantum dots for photonic quantum information technology
No full textThe generation, manipulation, storage, and detection of single photons play a central role in emerging photonic quantum information technology. Individual photons serve as flying qubits and transmit the relevant quantum information at high speed and with low losses, for example between individual nodes of quantum networks. Due to the laws of quantum mechanics, the associated quantum communication is fundamentally tap-proof, which explains the enormous interest in this modern information technology. On the other hand, stationary qubits or photonic states in quantum computers can potentially lead to enormous increases in performance through parallel data processing, to outperform classical computers in specific tasks when quantum advantage is achieved. In this review, we discuss in depth the great potential of semiconductor quantum dots in photonic quantum information technology. In this context, quantum dots form a key resource for the implementation of quantum communication networks and photonic quantum computers, because they can generate single photons on demand. Moreover, these solid-state quantum emitters are compatible with the mature semiconductor technology, so that they can be integrated comparatively easily into nanophotonic structures such as resonators and waveguide systems, which form the basis for quantum light sources and integrated photonic quantum circuits. After a thematic introduction, we present modern numerical methods and theoretical approaches to device design and the physical description of quantum dot devices. We then introduce modern methods and technical solutions for the epitaxial growth and for the deterministic nanoprocessing of quantum devices based on semiconductor quantum dots. Furthermore, we highlight the most promising device concepts for quantum light sources and photonic quantum circuits that include single quantum dots as active elements and discuss applications of these novel devices in photonic quantum information technology. We close with an overview of open issues and an outlook on future developments
Anaerobic digestion of spent coffee grounds : A study on long-term stable operation and improved methanation
No full textDepartment of Urban and Environmental Engineering (Environmental Science and Engineering)With the increase in world coffee consumption, the global spent coffee grounds (SCG) produced worldwide is estimated at 18 million wet tons in 2021. The annual production of SCG in the Republic of Korea also increased approximately 1.6-fold from 93,397 tons in 2012 to 149,038 tons in 2019. Although SCG has high potential to be utilized as compost, construction material, and biofuel feedstock, most of which is disposed by incineration or landfill, potentially leading to serious environmental pollution. For a sustainable management of SCG, methanation through anaerobic digestion (AD) has been considered an attractive option to treat organic-rich SCG due to its ability to convert organic waste into biogas, a carbon-neutral energy source.
However, previous studies have concluded that the stable long-term mono-digestion of SCG as a sole substrate cannot be achieved and the reasons for the failure were not suggested. Several experimental attempts have been made in recent studies to overcome the limitation of AD fed with SCG. Pretreatment of lignocellulosic biomass has been widely used to enhance its degradability by increasing its accessibility to hydrolytic bacteria. Previous studies have reported the batch test results of pretreated SCG, which showed improved methane production compared with non-pretreated SCG. However, long-term continuous methanation of pretreated SCG has not been reported yet. Anaerobic co-digestion studies have been conducted using various co-substrates including waste activated sludge, food waste (FW), and Ulva biomass. Although co-digestion studies have reported continuous operation with SCG co-feeding, stable and robust methanation of SCG has not been achieved. Therefore, the AD of SCG was investigated to achieve long-term stable operation and improved methanation.
In Study I, the pretreatment method was applied to increase the hydrolysis efficiency of SCG, under the assumption that the lignocellulosic characteristic of SCG is the barrier to SCG mono-digestion. Thermo-alkaline pretreatment was chosen to minimize the chemical cost. A response surface analysis was performed using solubilization and batch test data within given range (0???0.2 M NaOH and 60???90 ???) to determine the optimum condition for the biomethanation of pretreated SCG. The batch test results showed that increasing NaOH concentrations and temperatures had positive effects on SCG solubilization and that methane production increased only when the NaOH concentration increased up to a certain level due to sodium inhibition. In addition, continuous test with the optimum pretreatment condition obtained in the batch test revealed serious deterioration after 3 volume turnovers, showing decreased methane production simultaneously with the accumulation of volatile fatty acids (VFAs). The nutrient deficiency might be the reason for the deterioration in pretreated SCG digestion.
In Study II, FW and SCG (FW:SCG = 10:1, based on volatile solids (VS)) were co-digested to supplement the nutrient and dilute potential inhibitory compounds in SCG. Severe system failure with a drastic decrease in methane production and accumulation of VFAs was observed in duplicate reactors after co-feeding SCG into the existing anaerobic FW digesters, while stable operation was achieved with mono-digestion of FW. Neither the nitrogen source nor the alkalinity was the reason for the deterioration. The substrate feeding to both reactors was stopped for performance stabilization (i.e., restoration in batch mode), but different stabilization strategies were adopted for each digester. Nutrient-rich Ulva biomass (FW:SCG:Ulva = 10:1:0.5, based on VS) was co-fed to help restore stable performance, but its effects were significantly different between the digesters, presumably because of the different stabilization strategies used. Therefore, the addition of 10% SCG to the anaerobic FW digesters revealed that stable biomethanation is difficult to achieve without nutrient addition.
In Study III, a very small amount of SCG was added into the anaerobic FW digesters to investigate how much SCG can be added into FW-treating digesters without compromising the process performance and stability. The anaerobic FW digesters with trace elements (Fe, Co, and Ni) were co-fed with 1%, 2%, 4%, and 10% of SCG and showed a significant increase in methane yield when 1???4% SCG was added. With the trace element supplement, co-feeding with 10% SCG demonstrated a stable operation without compromising the process performance and achieved methane yield similar to that with 4% SCG co-feeding and a slightly reduced organic removal efficiency. The improved methane yield appeared to be due to the increased protein removal efficiency as the amount of SCG increased. The results of the microbial community and functional potential analyses suggested that proteolytic bacteria possibly contributed to the enhancement of protein removal efficiency with the addition of SCG, which consequently led to the improved methane yield.
In conclusion, this Ph.D. dissertation examined the long-term stability of SCG AD and proposes an optimal dose of SCG for the treatment of anaerobic FW digesters. The annual SCG production in the Republic of Korea is approximately 2.9% of FW production. Even if FW production in the country is usually managed by other methods (i.e., composting and animal feed making), the annual SCG production is still only approximately 10.5% of the annual FW handled by biogasfication facilities. Therefore, if the concentrations of trace elements in the digester can be sufficiently maintained, managing SCG using an existing anaerobic FW digester is reasonable. However, it is recommended that co-digest up to 4% of SCG in anaerobic FW digesters to maintain process stability and methane yield increases.clos