This paper presents a technique for content-based image retrieval (CBIR) by exploiting the advantage of low-complexity ordered-dither block truncation coding (ODBTC) for the generation of image ...content descriptor. In the encoding step, ODBTC compresses an image block into corresponding quantizers and bitmap image. Two image features are proposed to index an image, namely, color co-occurrence feature (CCF) and bit pattern features (BPF), which are generated directly from the ODBTC encoded data streams without performing the decoding process. The CCF and BPF of an image are simply derived from the two ODBTC quantizers and bitmap, respectively, by involving the visual codebook. Experimental results show that the proposed method is superior to the block truncation coding image retrieval systems and the other earlier methods, and thus prove that the ODBTC scheme is not only suited for image compression, because of its simplicity, but also offers a simple and effective descriptor to index images in CBIR system.
This paper presents an effective image retrieval method by combining high-level features from convolutional neural network (CNN) model and low-level features from dot-diffused block truncation coding ...(DDBTC). The low-level features, e.g., texture and color, are constructed by vector quantization -indexed histogram from DDBTC bitmap, maximum, and minimum quantizers. Conversely, high-level features from CNN can effectively capture human perception. With the fusion of the DDBTC and CNN features, the extended deep learning two-layer codebook features is generated using the proposed two-layer codebook, dimension reduction, and similarity reweighting to improve the overall retrieval rate. Two metrics, average precision rate and average recall rate (ARR), are employed to examine various data sets. As documented in the experimental results, the proposed schemes can achieve superior performance compared with the state-of-the-art methods with either low-or high-level features in terms of the retrieval rate. Thus, it can be a strong candidate for various image retrieval related applications.
The exploration of value‐added conversions of naturally abundant amino acids has received considerable attention from the synthetic community. Compared with the well‐established asymmetric ...decarboxylative transformation, the asymmetric deaminative transformation of amino acids still remains a formidable challenge, mainly due to the lack of effective strategies for the C−N bond activation and the potential incompatibility with chiral catalysts. Here, we disclose a photoinduced Cu‐catalyzed asymmetric deaminative coupling reaction of amino acids with arylboronic acids. This new protocol provides a series of significant chiral phenylacetamides in generally good yields and excellent stereoselectivity under mild and green conditions (42–85 % yields, up to 97 % ee). Experimental investigations and theoretical calculations were performed to reveal the crucial role of additional phenols in improving catalytic efficiency and enantiocontrol.
A visible light induced enantioselective deaminative arylation of amino acid derivatives by bifunctional copper catalysis is disclosed. A variety of α‐aryl‐N‐phenylamides are prepared with good efficiency and high enantioselectivity. A possible reaction mechanism and an asymmetric induction mode have been proposed based on experimental and computational evidence.
We propose an effective method to boost the accuracy of multi-person pose estimation in images. Initially, the three-layer fractal network was constructed to regress multi-person joints location ...heatmap that can help to enhance an image region with receptive field and capture more joints local-contextual feature information, thereby producing keypoints heatmap intermediate prediction to optimize human body joints regression results. Subsequently, the hierarchical bi-directional inference algorithm was proposed to calculate the degree of relatedness (call it Kinship) for adjacent joints, and it combines the Kinship between adjacent joints with the spatial constraints, which we refer to as joints kinship pattern matching mechanism, to determine the best matched joints pair. We iterate the above-mentioned joints matching process layer by layer until all joints are assigned to a corresponding individual. Comprehensive experiments demonstrate that the proposed approach outperforms the state-of-the-art schemes and achieves about 1% and 0.6% increase in mAP on MPII multi-person subset and MSCOCO 2016 keypoints challenge.
With the increasing global electromagnetic pollution, it is more and more important to develop lightweight, flexible, and high electromagnetic shielding materials. Two-dimensional (2D) transition ...metal material MXenes have good conductivity and excellent electromagnetic shielding performance. Herein, a facile and effective method is reported to synthesize lightweight and flexible MXene/CNF/silver (MCS) composite membranes with a brick-like structure and high-performance electromagnetic interference shielding. MCS composite membranes have an electromagnetic shielding performance of 50.7 dB due to MXene self-reduction of silver nanoparticles and the brick-like structure, compared with that of MXene/CNF (MC) membranes ( 14.98 dB). In addition, the MCS composite membranes exhibit super-thin thickness (46 μm) and good tensile strength (up to 32.1 MPa), and their good mechanical properties are attributed to the addition of CNFs. Moreover, the MCS composite membranes show good electrical conductivity (588.2 S m
−1
). Therefore, MCS composite membranes that are lightweight and flexible and have high electromagnetic shielding performance can replace other electromagnetic shielding materials and be used in aerospace, weapon equipment, and wearable smart materials.
Flexible and lightweight MXene/CNF/silver composite membranes are vacuum filtered to form a high electromagnetic shielding material with a brick-like structure. The membranes have an excellent electromagnetic shielding performance of 50.7 dB.
The ongoing outbreak of coronavirus disease 2019 (COVID-19) has spread rapidly on a global scale. Although it is clear that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted ...through human respiratory droplets and direct contact, the potential for aerosol transmission is poorly understood
. Here we investigated the aerodynamic nature of SARS-CoV-2 by measuring viral RNA in aerosols in different areas of two Wuhan hospitals during the outbreak of COVID-19 in February and March 2020. The concentration of SARS-CoV-2 RNA in aerosols that was detected in isolation wards and ventilated patient rooms was very low, but it was higher in the toilet areas used by the patients. Levels of airborne SARS-CoV-2 RNA in the most public areas was undetectable, except in two areas that were prone to crowding; this increase was possibly due to individuals infected with SARS-CoV-2 in the crowd. We found that some medical staff areas initially had high concentrations of viral RNA with aerosol size distributions that showed peaks in the submicrometre and/or supermicrometre regions; however, these levels were reduced to undetectable levels after implementation of rigorous sanitization procedures. Although we have not established the infectivity of the virus detected in these hospital areas, we propose that SARS-CoV-2 may have the potential to be transmitted through aerosols. Our results indicate that room ventilation, open space, sanitization of protective apparel, and proper use and disinfection of toilet areas can effectively limit the concentration of SARS-CoV-2 RNA in aerosols. Future work should explore the infectivity of aerosolized virus.
Drowsiness and fatigue of the drivers are amongst the significant causes of the car accidents. Every year the number of deaths and fatalities are tremendously increasing due to multifaceted issues ...and henceforth requires an intelligent processing system for accident avoidance. In relevant with this, an effective driver drowsiness detection system is proposed. The main challenges are robustness of the algorithm towards variation of the human face and real-time processing capability. The first challenge pertaining to the facial variation has been handled well using conventional image processing and hand-craft features of computer vision algorithms. Yet, variations such as facial expression, lighting condition, intra-class variation, and pose variation are additional issues that conventional method failed to address. Deep learning is an alternative solution which provides a better performance by learning features automatically. Thus, this paper proposed a new concept for handling the real-time driver drowsiness detection using the hybrid of convolutional neural network (CNN) and long short-term memory (LSTM). The performance of the system has been tested using the public drowsy driver dataset from ACCV 2016 competition. The results show that it can outperform the former schemes in the literature.
Small heat shock proteins (sHSPs) have been thought to function as chaperones, protecting their targets from denaturation and aggregation when organisms are subjected to various biotic and abiotic ...stresses. We previously reported an sHSP from Oryza sativa (OsHSP20) that homodimerizes and forms granules within the cytoplasm but its function was unclear. We now show that OsHSP20 transcripts were significantly up-regulated by heat shock and high salinity but not by drought. A recombinant protein was purified and shown to inhibit the thermal aggregation of the mitochondrial malate dehydrogenase (MDH) enzyme in vitro, and this molecular chaperone activity suggested that OsHSP20 might be involved in stress resistance. Heterologous expression of OsHSP20 in Escherichia coli or Pichia pastoris cells enhanced heat and salt stress tolerance when compared with the control cultures. Transgenic rice plants constitutively overexpressing OsHSP20 and exposed to heat and salt treatments had longer roots and higher germination rates than those of control plants. A series of assays using its truncated mutants showed that its N-terminal arm plus the ACD domain was crucial for its homodimerization, molecular chaperone activity in vitro, and stress tolerance in vivo. The results supported the viewpoint that OsHSP20 could confer heat and salt tolerance by its molecular chaperone activity in different organisms and also provided a more thorough characterization of HSP20-mediated stress tolerance in O. sativa.
High-performance conductive hydrogels are desired for the development of flexible wearable sensors. However, it remains a challenge to simultaneously realize high stretchable, freezing tolerance, and ...attractive conductivity through a simple approach. In this work, we present stretchable, water retention, anti-freezing, and conductive hemicellulose/polypyrrole (H/PPY) composite hydrogels for application in epidermal strain sensors via freezing-thawing method. The composite hydrogels were obtained using hemicellulose as a hydrophilic carrier and polypyrrole as a conductive matrix. The freezing and thawing temperatures of the hydrogels decreased and the conductivity increased benefiting from the introduction of glycerol and NaCl. The hydrogels had good mechanical properties, remodeling ability and water retention after storage for 7 days. In addition, the strain sensors assembled by hydrogels accurately monitored the signals of human motions with good strain sensing durability. It is expected that the as-prepared hydrogels have the potential to be applied in the fields of wearable devices.
An Efficient Fusion-Based Defogging Jing-Ming Guo; Jin-yu Syue; Radzicki, Vincent R. ...
IEEE transactions on image processing,
2017-Sept., 2017-Sep, 2017-9-00, 20170901, Letnik:
26, Številka:
9
Journal Article
Recenzirano
Degradation in visibility is often introduced to images captured in poor weather conditions, such as fog or haze. To overcome this problem, conventional approaches focus mainly on the enhancement of ...the overall image contrast. However, because of the unspecified light-source distribution or unsuitable mathematical constraints of the cost functions, it is often difficult to achieve quality results. In this paper, a fusion-based transmission estimation method is introduced to adaptively combine two different transmission models. Specifically, the new fusion weighting scheme and the atmospheric light computed from the Gaussian-based dark channel method improve the estimation of the locations of the light sources. To reduce the flickering effect introduced during the process of frame-based dehazing, a flicker-free module is formulated to alleviate the impacts. The systematic assessments show that this approach is capable of achieving superior defogging and dehazing performance, compared with superior defogging and dehazing performance, compared with the state-of-the-art methods, both quantitatively and qualitatively.
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